Question:
You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
pulmonary sequestration ( ps ) is a rare developmental disorder characterized by the presence of a nonfunctioning lung parenchyma that lacks normal tracheobronchial tree connection and is supplied by a systemic artery.1
  congenital diaphragmatic hernia ( cdh ) is a malformation characterized by a diaphragmatic defect through which the abdominal viscera migrate into the chest during fetal life.2
  the association between ps and cdh has been previously described.1
 2
 3
 4
 5
 6
 7 we report the case of a neonate affected by prenatally diagnosed cdh treated by thoracoscopy . during the procedure
, we detected an associated extralobar ps , which was preoperatively undiagnosed , and removed it .
a female infant was delivered by elective cesarean section at 35 weeks of gestation and was referred to our department for prenatal diagnosis of left diaphragmatic hernia detected at 32 weeks of gestation by ultrasounds and characterized by a lung - to - head ratio ( lhr ) of 1.6 .
weight at birth was 3,400  g , and apgar index was 9 at 1 minute and 10 at 5 minutes , respectively . at birth , the newborn underwent nasotracheal intubation and high - frequency oscillatory ventilation , positioning of a nasogastric tube , and chest x - ray that confirmed prenatal diagnosis . during the first day of life ,
the patient maintained clinical stability , so we decided for surgical correction through thoracoscopic approach on the second day of life .
a 5-mm trocar was positioned in the fifth intercostal space over the middle axillary line , and two further operative trocars ( 3 mm , reusable ) were placed in the sixth intercostal space over the anterior and posterior axillary line , respectively .
capnothorax was created with a 6mmhg pressure and 0.5l / min flow , and maintained with intermittent insufflation to reduce side effects of co2 absorption .
once entered in the pleural cavity , we noted a diaphragmatic hernia with a sac .
a basal extralobar sequestration was also detected and removed after ligation of the feeding artery with two endoloops ( fig .
the diaphragmatic defect was repaired with an interrupted 3/0 braided polyester suture ( ethibond ) ( figs . 2 and 3 ) .
the patient underwent first follow - up chest x - ray after 2 months , and she is currently asymptomatic without radiologic signs of recurrence ( 6-month follow - up ) .

ps includes two forms : intralobar ps ( within the normal parenchyma ) , which is the most common form , and extralobar pulmonary sequestration ( eps).1 eps has its own pleural covering and can be located inside or outside the thorax .
the associations are more common in the extralobar type and include congenital pulmonary airway malformation , configuring a lesion termed as  hybrid lesion ,  congenital heart disease , and cdh in up to 15 to 40% of cases.7
 8
 9
 10
a possible explanation is the interference related to the presence of a sequestered lung mass with the fusion of diaphragmatic components ( mechanical obstacle).7
 11
  in recent years , there has been speculation on the prognosis associated with the two simultaneous defects ( cdh and ps).7 ps can be associated with pulmonary hypoplasia , and being a space - occupying lesion , it could constitute a further obstacle to lung development.3
 8
  indeed , the prognosis of ps combined with cdh remains unclear , and although there is not sufficient evidence regarding the influence of ps on cdh prognosis , some authors hypothesized that ps acts as a protective factor during pregnancy and probably improves the prognosis of patients with cdh.7 two possible explanations for this improved outcome may be given : ( 1 ) ps acts as an anatomical barrier to the rise of the abdominal viscera ; ( 2 ) ps causes a mediastinal shift leading to an underestimation of lhr , thus distorting the prognosis that seems poorer.7
  prenatal identification of both cdh and ps is possible , and frequently occurs.7 in our case , prenatal diagnosis of concurrent cdh and ps was not possible probably because herniated organs obscured the presence of a sequestered lung mass .
the treatment of choice of a symptomatic eps in addition to a cdh is surgical excision.1
 2 however , some authors recommend observation of asymptomatic eps , as these lesions rarely produce complications.12 we believe that resection should be the treatment of choice in all cases since there are hybrid lesions misdiagnosed as pure sequestrations and one can never be sure that the lesion will remain asymptomatic.4 the most frequent argumentation for removal is the prevention of recurrent infections and malignancy .
malignancy has been reported to be associated to cystic lesions , in particular to type i congenital cystic adenomatoid malformation in 1% of cases.12 although the risk is quite low , in case of recurrent infections or neoplastic evolution , the previous  wait and see  approach would be difficult to justify . regarding the surgical approach , minimally invasive alternatives to the traditional surgical technique have been recently proposed , although the best approach to cdh is controversial.2 recently , hypercapnia and acidosis during thoracoscopy in newborns have been reported.13
 14 in our case , we used co2 insufflation at the beginning of the procedure to facilitate reduction of herniated organs only for brief periods to improve visibility .
the distinction between a diaphragmatic hernia with sac and a congenital localized eventration may be difficult .
sac removal seems to be associated with a lower recurrence rate,15 but during thoracoscopy the presence of a sac can facilitate reduction , can lessen visceral trauma , and keeps the two cavities separate.2 according to a recent survey among the international pediatric endosurgery group members,16 22% of surgeons declared to leave the sac in place during the thoracoscopic repair of cdh , so this approach is quite accepted even if in a minority of cases .
accurate closure of this vessel is mandatory to avoid postoperative bleeding , which can be life - threatening.17 in case of eps , vessel sealing can be achieved with different devices such as ligasure , clips , and ligation . in this case , since the eps was of limited size , we closed the feeding artery with two endoloops and cut the vessel with cold scissors to avoid thermic damage of the ligatures
. we would probably have missed the ps using a different surgical approach ( classical laparotomy ) , as during the laparotomic approach the posterior position of the diaphragmatic defect makes it hard to inspect the entire hypoplastic lung that is atelectatic and displaced in the upper part of the chest .
the thoracoscopic approach for cdh offers the advantage to easily diagnose and treat associated lung lesions .
the case report describes the usefulness of thoracoscopy as diagnostic and therapeutic tool in case of diaphragmatic hernia associated with undiagnosed lung malformation .
thoracoscopy allows to explore thoracic cavity looking for lung lesions that are associated to diaphragmatic hernia in 1540% of cases and to remove them .

Answer:
we report the case of a neonate affected by prenatally diagnosed congenital diaphragmatic hernia ( cdh ) , treated by thoracoscopy . during the procedure , we detected an associated extralobar pulmonary sequestration ( eps ) , which was preoperatively undiagnosed , and we removed it .
 eps has been shown to be associated with cdh in up to 15 to 40% of cases .
 a possible explanation hypothesized is that pulmonary sequestration , which develops at 4 to 5 weeks of gestation , can disturb the fusion of the diaphragm and closure of the pleuroperitoneal canal .
 the thoracoscopic approach permitted us to identify the thoracic eps that probably would have been otherwise missed .


Question:
You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:

 musculoskeletal disorders are one of the most common causes of occupational injuries and disability in industrialized nations and developing countries ( 1 - 3 ) . a variety of risk factors are involved in the occurrence of the damage that can be divided by physical factors such as poor posture , ergonomics , lifting , and carrying heavy loads and working with repetitive movements ( 4 ) , psychological , organizational , and individual factors ( 5 )
. these disorders mainly occur in the upper extremities such as hands , wrists , arms , shoulders , neck , and waist ( 6 ) .
these disorders occur due to repetitive movements that led to the injury of nerves , tendons , joints , cartilage or disks between the vertebrae ( 7 ) .
factors that cause these disorders are awkward posture , repetitive movements , and excessive force .
the signs of musculoskeletal symptoms are muscle pain , discomfort , numbness down , burning , tenderness , swelling , limited range of motion , and loss of power . a long repetitive movement of the body ( 8) causes these pains .
according to the previous studies , there is a significant relationship between musculoskeletal disorders and repetitive motion .
several professionals such as surgeons and personnel of the operating rooms are at risk of these symptoms .
the surgeons perform the surgery in a standing position , and the hands are generally in motion in surgery .
sometimes a fixed posture continues for hours and the pressure exerted by the musculoskeletal organs is too high ( 11 ) . over time , the continuous exposure to biomechanical and psychosocial stressors may intensify the musculoskeletal injuries in the workplace . because surgery is often subtle , sensitive , and time - consuming ,
ergonomics aims at helping the surgeons to work without feeling any pain , or stress , and with less error ( 12 ) .
nowadays , various surgical procedures are done such as open surgery , laparoscopy , and microsurgery ( 13 ) .
the body posture of the surgeons during open surgeries is described as a head - bent and back - bent posture .
surgeons maintain this posture for long periods ; and as a result , they experience physical discomfort during and after the surgery ( 13 ) . during laparoscopic procedures , the body movement of the surgeon is very limited , resulting in a more static upright body posture compared to open surgery ( 13 ) . due to the position and depth of the incision during open surgery , surgeons have a fixed work posture , tending to work with arms abducted and unsupported ( 14 ) .
for instance , repetitive motion of the wrist in laparoscopic surgery , and neck static posture in microsurgery could cause musculoskeletal disorders ( 14,15 ) .
in addition to improper posture due to ergonomics , repetitive movements of the hands and wrists , neck and shoulders , and excessive force can ultimately cause or exacerbate these effects ( 16 ) .
according to healthcare professionals , multiple ergonomic risk factors in the operating rooms can lead to or aggravate musculoskeletal symptoms .
moreover , no comprehensive study has been conducted to evaluate and compare the ergonomic risk factors in these 3 types of surgeries .
this study aimed at evaluating the role of various ergonomic risk factors in the frequency or resonance frequency of musculoskeletal symptoms in surgeons who perform surgery ( open surgery , laparoscopy , and microsurgery ) in a hospital of iran university of medical sciences .

eighty - one male surgeons who consistently worked at milad hospital in tehran participated in this study .
each of these surgeons exclusively conducted one of the 3 types of open surgery , laparoscopy , and microsurgery . after interviewing the surgery team , to determine the prevalence of musculoskeletal symptoms , the nordic questionnaire ( a questionnaire made by kurinka et al . at the institute of occupational health in 1987 ) was used ( 17 ) . in this study
demographic information such as age , height , weight , work experience , and number of hours per day were added to the questionnaire .
to estimate and evaluate the ergonomic risk factors in each of these three types of surgery wera method was used .
the wera covers an extensive range of physical risk factors including posture , repetition , forceful , vibration , contact stress , and task duration , and it assesses the five main body regions ( shoulder , wrists , back , neck and legs ) ( 18 ) .
eighty - one surgeons who performed the 3 following types of surgeries participated in this study : open surgery ( n=26 ) , laparoscopy ( n=28 ) , and microsurgery ( n=27 ) .
each of the surgery types was observed using the wera tool . during the surgery ,
observation of the workplace was carried out by recording the surgeries using a video camera .
the three types of surgery were observed and videotaped to collect data for the wera assessment .
the angle of the body segments relative to the vertical position was estimated ( shoulders , wrists , back , neck and legs ) using the video tapes ( 18 ) .
the participants were middle aged and experienced ( 5.4 years of work experience ) .

table 2 demonstrates the prevalence of musculoskeletal disorders that the surgeons experienced during the past 12 months .
the prevalence of symptoms in the neck , back , shoulder , and arm was high ; and a high percentage of the participants involved in all the 3 types of surgeries ( open surgery , laparoscopy , and microsurgery ) .
no significant difference was found in the prevalence of musculoskeletal symptoms in the body of the surgeons performing these 3 types of surgeries .
  *
friedman two - way analysis of the variance test
 table 3 displays the evaluations of the wera scores .
the average of wera final score is 40.11 , representing an upward risk for musculoskeletal disorder in 3 types of surgeries . in this study ,
the wera score of laparoscopic surgery had a significant relationship with back problems ( r=0.61 , p=0.02 ) , wrist ( r=0.53 , p=0.03 ) , and neck ( r=0.49 , p=0.02 ) .
musculoskeletal disorder had a significant relationship with the wera score ( r=0.48 , p=0.02 ) in open surgery , and ( r=0.46 , p=0.04 ) microsurgery .

 the aim of this study was to evaluate the relation of musculoskeletal disorders and ergonomic risk factors based on wera method in 3 types of surgery among the surgeons who were working in tehran 's hospitals .

 in this study , it was found that specified ergonomic risk factors , based on evaluating by wera , has a high impact on the prevalence of musculoskeletal symptoms . on the other hand ,
the type of surgery was the main cause of musculoskeletal disorders among surgeons who participated in this study . in a study on the prevalence of musculoskeletal symptoms in surgeons
, it was found that the highest prevalence was in the lower back , neck , and hands due to poor postures of the surgeons during surgery ( 19 ) . in another study ,
the most important cause of arthritis pain and disability was found to be long - term operating mode or standing back for long hours ( 11 ) .
therefore , the results of this study are consistent with those of the previous studies on the prevalence of musculoskeletal symptoms in surgeons .
musculoskeletal disorder is more common in laparoscopic surgery and open surgery due to incorrect posture , such as the need to bend neck and back ( 20 ) . on the other hand
, the prevalence of musculoskeletal symptoms in wrist of the surgeons had a direct relationship with instruments in this study , which is consistent with the results of previous studies ( 21 ) .
improper use of hand tools in the surgery caused musculoskeletal symptoms and back pain , especially in awkward postures ( 22 ) . in a study conducted on surgeons , the most complaints of the surgeons were related to limbs shoulder , wrist , and waist ( 23 ) . in another study ,
the highest prevalence was in the back , neck , and wrists , causing adverse deviation of the wrist posture from the normal posture ( 24 ) .

 among the most important tools used in laparoscopic surgery is grasper / loop , which causes poor posture of the body .
in addition , looking into a monitor for a long time increases the risk of musculoskeletal symptoms in laparoscopic surgeries in the cervical region ( 25 ) .
moreover , working with the surgical microscope for a long - time , improper postures , and improper seating increase the prevalence of musculoskeletal symptoms in the back and neck muscle areas while performing microsurgery ( 26 ) .

the results of this study revealed that the prevalence of musculoskeletal symptoms was high among the surgeons .
therefore , it is necessary to take action to solve this problem by using appropriate ergonomic tools , management solutions , and suitable design of surgical instruments . a standing - sitting ergonomic chair could be used to prevent back pain in open surgery . moreover , using a suitable chair can prevent improper postures . to prevent wrist musculoskeletal symptoms , surgical tools with ergonomic design and soft rubber handle
depending on the type of surgery training , using appropriate seats and ergonomic instruments are the best solution to reduce musculoskeletal symptoms in the surgeons .

 the results of this study revealed that the prevalence of musculoskeletal symptoms was high in 3 types of open surgery , laparoscopy , and microsurgery among the surgeons .
in addition , it was found that these symptoms were more prevalent in the neck , waist , and hands .
depending on the type of surgery , teaching appropriate methods , using equipment properly , and using proper ergonomic seats are the best strategy to reduce musculoskeletal symptoms in surgeons .

Answer:
background : musculoskeletal symptoms are the main cause of loss of working time , and increase in labor costs .
 poor posture is the most important risk factor for work - related musculoskeletal symptoms .
 this study aimed at evaluating the role of ergonomic risk factors in different surgical ( open surgery , laparoscopy , and microsurgery ) in the frequency or resonance frequency of musculoskeletal symptoms .

 methods : this descriptive - analytic study was conducted on 81 surgeons in a hospital in tehran . in this study , the prevalence of musculoskeletal symptoms was evaluated using the nordic questionnaire
 . moreover , workplace ergonomic risk assessment method ( wera ) was used to evaluate ergonomic risk factors in 3 types of open surgery , laparoscopy , and microsurgery .

 results : the results revealed that the prevalence of musculoskeletal symptoms of the neck , back , shoulder , and arm is high in surgeons ( over 75% ) .
 the mean final score of wera was 40.11 , representing the high risk of the 3 types of surgery for the prevalence of musculoskeletal symptoms .
 results revealed that the prevalence of musculoskeletal symptoms in the neck , waist and wrists had a significant relationship with the body posture in the 3 types of open surgery , laparoscopy , and microsurgery ( p<0.05 ) .

 conclusion : in the present study , the prevalence of musculoskeletal symptoms was high in the neck , waist , and hands surgeries .
 depending on the type of surgery , teaching correct working methods , using proper seats and ergonomic equipment are the best strategies to reduce musculoskeletal symptoms in the surgical profession .


Question:
You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:

 acute intussusception is one of the most common causes of acute abdomen in infants .
management includes both surgical and non - surgical methods , with gradually increasing importance recently being accorded to the latter .
conservative measures , including hydrostatic reduction , are the methods of choice for initial management . though widely accepted , the expertise is still not widely available , especially in developing countries .

 a six - month - old child presented with complaints of repeated episodes of vomiting that contained only ingested milk .
this was associated with three episodes of loose stools , initially watery and later with fresh red blood per rectum with jelly - like consistency .
there was no history of fever , decreased urine output , lethargy , abnormal body movements , or difficulty in breathing .
her immunizations were fully up to date with no history of rota virus immunization .

 on admission
abdominal examination was remarkable for an ill - defined mass that could be felt in the right hypochondrium .
she was initially kept nil per oral and started on conservative measures , including antibiotics .
an urgent abdominal ultrasonography was done , which showed a round mass - like lesion giving a target appearance in the right hypochondrium ( suggestive of ileocolic intussusception ) .
she was taken for immediate intervention , and as per surgical opinion , a hydrostatic reduction under radiological guidance was started .

the child was first stabilized using intravenous fluids to treat dehydration , and a pre - procedure x - ray abdomen was performed to rule out intestinal perforation .
the procedure was done in the ultrasonography room in the presence of a treating physician and a pediatric surgeon . without using any sedation ,
a 16 f foley catheter was inserted into the rectum in the supine position and the balloon was gently inflated while maintaining a tight anal seal .

the patient s vitals , which included abdominal girth and distension , were monitored throughout the procedure .
lactate solution , warmed to body temperature , was then slowly introduced into the catheter through a bag hanging at a height of approximately 100 cm . during reduction ,
the intussusceptum was observed under continuous ultrasound guidance as it proceeded to the cecum and then reduced across the ileocecal valve ( figures 1 - 4 ) .

ileal loop ( star ) within ascending colon ( arrow ) , longitudinal view .

this was associated with the patient s improved condition , which included less crying and irritability .
the parents were told about the possibility of recurrence and asked to pay close attention for the onset of symptoms .

 acute intussusception is defined as the telescoping of the proximal bowel ( intussusceptum ) into the distal bowel ( intussuscipiens ) .
the usual locations include the ileocolic region and ileocecal junction , which comprise the majority of cases .
intussusception mostly presents between four months and two years , while the peak incidence is found around middle infancy .

diagnosis usually needs a high suspicion on the part of the treating physician , as presentation can be quite varied , including irritability , vomiting , and poor feeding .
characteristic manifestations include crying episodes , fresh red blood in stools ( hematochezia ) , and a mass in the abdomen .
differential diagnoses include acute gastroenteritis , dysentery , sepsis syndrome , and volvulus , amongst others .
the diagnosis is usually confirmed sonographically , which is highly accurate and has a reported sensitivity that exceeds 90% .
various signs have been described in the literature , depicting intussusception as an abdominal mass with a target sign on the transverse section , a pseudokidney ( or sandwich sign ) on the longitudinal section , and a crescent - in - doughnut sign on axial images .

the management of intussusception has seen a paradigm shift in recent years . in the past , the preferred non - surgical method involved use of a barium enema for reduction , followed by the air insufflation method .

hydrostatic reduction using ultrasound - guided saline reduction has recently gained acceptance as the procedure of choice for initial nonsurgical management of intussusceptions in children .
this popularity can be attributed to the avoidance of radiation exposure to the child and the treating team , as well as to the high success rates that have been achieved .

there is still some controversy regarding the exact method of the procedure , which can be attributed to the poor training of physicians and to the general belief that intussusception is entirely a surgical problem , especially in developing countries .
this procedure should be undertaken with a close liaison between pediatrics , pediatric surgery , and radiology teams to obtain the best results .
the surgeon and physician should always be present at the time of reduction for clinical monitoring .

after adequate optimization , including temperature controlled settings , the procedure should ideally be undertaken without any sedation .
this is helpful for assessing a successful reduction using clinical criteria , as described later .

we used ringer s lactate due to its near physiological constitution , avoiding the risk of chemical peritonitis due to a barium enema or tension pneumoperitoneum due to an air enema , as seen in cases of intestinal perforation .
the risk of intestinal perforation following such a procedure is rarely encountered due to less hydrostatic pressure exerted and an even amount of pressure exerted on the bowel walls as compared to air insufflations . even if intestinal perforation occurs
we chose 100 cm h2o pressure to lessen the risk of perforation , though different studies have used a wide range of pressures ( 75 to 125 cm h2o).6 ,
 9

 the main ultrasonographical criteria of successful reduction is the flow of the fluid from the cecum into the terminal ileum .
general improvement in the clinical profile of the patient including relief from crying , stable vitals , increasing abdominal distension during the procedure ( which indicates filling of the small bowel ) , and the disappearance of the abdominal mass , should also be given due consideration when deciding to terminate the procedure .

a repeat ultrasound should always be done after the procedure as the chances of recurrence is high , especially in the immediate post - procedure period .
, this method should be undertaken as teamwork , and not considered the work of a single specialty , which is the best way of treating the patients according to the standards of today .

Answer:
we present a case of infantile intussusception treated successfully using hydrostatic reduction , highlighting the importance of non - surgical techniques as the first line of management for this entity .
 physicians should strive for mastery over such techniques by extensive training to prevent unwanted surgical procedures in such cases .


Question:
You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
mllerian anomalies are congenital defects of the female reproductive tract resulting from failure in the development of the mllerian ducts and their associated structures
symptoms appear principally during adolescence or early adulthood , and affect the reproductive capacity of these women .
when clinically suspected , investigations leading to diagnosis include imaging methods such as hysterosalpingography , ultrasonography , magnetic resonance imaging , and cystoscopy .
a 25-year - old nulliparous lady , presented to the gynecology opd with complaints of inability to conceive .
she was married for 7 years , cohabiting since 5 years . at 16 years of age , she consulted a local doctor in her village for primary amenorrhea and cyclical pain in abdomen , where some operative procedure was done . since then the patient has passage of blood mixed urine periodically every month for 2 to 3 days with suprapubic abdominal pain .
external urethral meatus appeared dilated , and there was blindly ending vagina approximately 3 cm in length . on per rectum
examination , uterus appeared normal in size and there was no bulge felt below it to suggest any collection . on investigations ,
the ultrasound showed normal uterus with endometrial thickness 9.5 mm , ovaries were normal , and bilateral kidneys were also normal .
mri of abdomen showed normal uterine body and cervix with small amount of fluid in endometrial cavity , endocervical cavity , and in upper part of vagina ; below that there was a transverse vaginal septum of about 3.5 cm in thickness .
[ figure 1 ] on cystoscopy , a fistulous opening of approximately 2 mm was seen below the internal sphincter of urethra through which menstrual blood was seen coming out ; the bladder and ureteric orifices were normal .
vaginoplasty and repair of fistulous communication between the genital tract and the urethra was planned for the patient .
the mri shows uterus with cervix and upper 2 cm of vagina containing some blood products .
there is a septum between the upper and lower part of vagina ( the lower part identified by tampon in vaginal canal ) the woman was subjected to operation using abdominoperineal approach .
on laparotomy , uterus was normal in size , bilateral tubes were present , and ovaries were normal .
the methylene blue dye was injected into the fundus of the uterus ; dye was visualized coming out of urethra by the side of the indwelling catheter . from the perineal approach
, a transverse incision was made through the vault of the short vagina , the dissection was done upward in the connective tissue between the bladder above and rectum below and vaginal space was created .
after sharp and blunt dissection , cervix was visualized as dye was coming through it .
the urethrovaginal fistulous tract was identified and repair was done in two layers . over the raw area of vagina ,
the mould change was done after a week ; the amnion graft had successfully taken up .
the patient was found to be fine at follow - up after a month , with no hematuria and normal menstruation .
she was explained about the fertility period and asked to come at 3 monthly follow - up .
when a mullerian duct becomes obstructed , the patient may present with an abdominal mass and dysmenorrhea .
if the patient is not treated in a timely fashion , the consequences can be severe , extending even to infertility . in this case
, there was transverse vaginal septum in the upper part of vagina leading to hematocolpus and amenorrhea .
an iatrogenic fistulous tract was probably created which led to cyclical hematuria . magnetic resonance imaging ( mri )
is the mainstay in imaging for the evaluation of mullerian agenesis and is considered a very useful diagnostic tool . in our case ,
mri determined the precise mullarian anomaly giving us the details regarding the presence of normal cervix with precise length of vaginal septum to help us judge the prognosis and success of the operative procedure , but we got no information about the fistulous communication as it was quite fine and narrow .
the site of the opening of fistulous tract in the urethra was apparent on cystoscopy and led to the assumption that the other end tract opened in the vagina .
therefore , apart from mri , cystoscopy played a major role in determining the anomaly in this case . upon literature review of cases with genitourinary fistula
the fistula in that case , however , was congenital , unlike our case in which it was iatrogenic in all probability .
it also presented with cyclical hematuria with no incontinence of urine due to imperforate hymen .
congenital vesicouterine , cervicovesical , and vesicovaginal fistula associated with other mullarian anomalies has also been reported in literature.[46 ] iatrogenic fistulous communication between the genital tract and the urinary tract , known to occur as a complication of cesarean section , has been described in literature as  youssef 's syndrome .
it is characterized by cyclical hematuria , absence of vaginal bleeding , and complete urinary continence . in all these reports
in which there was a fistulous communication between the urinary and the genital tract , cystoscopy , hysterosalpingography , and dye test were required for confirmatory diagnosis and only computerized tomography ( ct ) or mri did not give the full clinical picture .
this report highlights the diagnostic and therapeutic challenge faced by the clinician in dealing with a fistulous genital and urinary tract communication with obstructing transverse vaginal septum .
increasing awareness of this rare entity calls for more meticulous evaluation before any surgical intervention in patients with complex genitourinary anomalies .

Answer:
we present a case of iatrogenic urethrovaginal fistula with transverse vaginal septum .
 the patient presented with cyclical hematuria and infertility .
 the vagina was blind - ending .
 the magnetic resonance imaging ( mri ) showed normal uterus with transverse vaginal septum .
 the cystoscopic examination during cyclical hematuria revealed bloody efflux through a small fistula below the internal urethral sphincter .
 vaginoplasty and repair of the urethrovaginal fistula was done .
 the vagina was reconstructed using an amniotic mould .
 the report emphasizes the importance of mri and cystoscopy in diagnosing such rare and complex anomalies .


Question:
You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
heart transplantation continues to provide patients with end - stage heart disease with extended survival with a half - life of 9.3 years between 2000 and june 2008 . .
however , despite substantial advancements in immunosuppression , patients continue to be at significant risk for allograft rejection early after cardiac transplantation .
the two recognized forms of allograft rejection are acute cellular rejection and antibody - mediated rejection ( amr ) .
while acute cellular rejection has historically been the most common cause of allograft dysfunction , amr has only recently become widely accepted . during the 2004 international society of heart and lung transplantation ( ishlt ) ,
cellular rejection grades were revised and amr was formally defined . in april 2010 , a publication from the ishlt consensus conference assessed the status of amr in heart transplantation and a pathologic grading scale was devised . despite the advent of new technology , such as gene expression profiling and echocardiograms , endomyocardial biopsy remains the standard for detecting rejection . to minimize the risk of a false negative , multiple specimens ( usually 35 ) are obtained from 3 different sites . though rare
, false negatives do exist either through sampling error , artifact , quilty lesions , or pathology misread .
prior to the 2010 consensus conference , hemodynamic compromise , in the absence of acute cellular rejection , was termed biopsy - negative rejection .
although the prevalence of the so - called biopsy - negative rejection has declined with the clinical diagnosis of amr , there are incidences of patients who present with cardiac dysfunction ( left ventricular ejection fraction , lvef  45% ) but have no biopsy findings of cellular or antibody - mediated rejection .
since the outcome of patients with bnr ( which includes cardiac dysfunction ) has not been well established , we sought to review the characteristics and treatment response of patients who have developed bnr after heart transplantation .
we retrospectively reviewed our cohort of patients who underwent heart transplantation between 2002 and 2012 and found 12 cases of bnr in 11 heart transplant patients , as defined by patients presenting with cardiac dysfunction , characterized by lvef  45% , and who had no biopsy findings of cellular rejection or amr .
as severe infections are also known to cause left ventricular dysfunction , patients with a clear clinical picture of sepsis with fever , increase in white blood count , or positive cultures were excluded .
continuous variable was presented as mean  standard deviation while categorical variable is presented as percentages .
we identified 11 patients who underwent heart transplantation between 2002 and 2012 and were treated for bnr .
none of the bnr patients had previous blood transfusion or previous transplant . 5 ( 45% ) patients had a previous vad placement and 1 ( 9% ) patient was african american .
the baseline immunosuppression medications are as follows : 5 patients ( 45% ) underwent induction therapy with antithymocyte globulin ( atg ) , 9 patients ( 82% ) initiated with tacrolimus and mycophenolate mofetil , 1 patient ( 9% ) initiated with cyclosporine and mycophenolate mofetil , and 1 patient ( 9% ) initiated with cyclosporine and azathioprine .
2 patients switched to cyclosporine from tacrolimus because of reduced seizure threshold ; 1 patient switched to a renal sparing protocol of sirolimus with mycophenolate mofetil because of renal function concerns .
the 12 cases of bnr presented with an average lvef of 34%  10% and 11 ( 92% ) treated cases occurred during the first - year after transplant ( table 3 ) .
the mean time to the first incidence of bnr is 7.8  7.5 months and no patient had treated rejection before onset of bnr except for the patient at the second onset . among the 106 biopsies that have been done before bnr , 24 ( 23% ) demonstrated low grade acute cellular rejection ( 1r , 1a , or 1b ) and 1 ( 0.9% ) showed suspicious antibody - mediated rejection ( amr 1 ) . de novo circulating antibodies developed in 3 cases ( in 3 patients ) and 1 of them had donor - specific antibodies . 4 out of the 12 cases presented with lvef  35% and presented with heart failure symptoms . of these 4 heart failure cases ,
2 required inotropic support  both received intravenous ( iv ) methylprednisolone ( 500  mg1000  mg per day for 3 days ) , atg ( 125150  mg per day for 35 days ) , and iv immunoglobulin ( ivig , 70  g per day for 3 days ) , followed by oral corticosteroids ( prednisone 80100  mg per day bolus and taper ) .
for the remaining 2 patients who presented with heart failure symptoms but did not necessitate inotropes , 1 was treated with atg and iv methylprednisolone followed by prednisone bolus and taper and the other was given iv methylprednisolone followed by prednisone only .
for the 8 out of 12 cases without heart failure symptoms , 7 were treated with only high dose oral corticosteroids .
overall , 7 cases ( 58% ) ( in 7 patients ) favorably resulted with return to normal left ventricular function ( lvef of 57%  6% ) within a mean of 14  10 days from the initial negative biopsy .
of these 7 patients , one expired approximately 6 months after the date of the normalized lvef and another one expired approximately 4 months after the date of normalized lvef . the remaining 5 cases ( in 5 patients , including 1 patient 's second case of bnr ) maintained persistent left ventricular dysfunction beyond 90 days .
a flow chart of treatment and effect could be found in figure 1 . in summary ,
the lvef status at 90 days is as follows : 5 cases ( in 5 patients , including 1 case as second bnr on a patient ) had persistent lv dysfunction , and 7 cases ( in 7 patients ) experienced normalized lvef .
as our understanding of the biological mechanisms underlying cardiac allograft rejection increases , the number of undiagnosed rejection decreases . the concept of bnr has evolved from its initial definition as hemodynamic compromise in the absence of acute cellular rejection to its current definition of patients presenting with cardiac dysfunction in the absence of biopsy findings of cellular rejection or amr .
amr has changed from being suggested as bnr to its own ishlt biopsy grading scale . however , even though the majority of rejection episodes of unclear etiology have now been resolved to be cases of amr , there are still cases where the biopsy findings are inconsistent with the clinical prognosis , that is , patients with a decrease in lvef with no biopsy findings of rejection , cellular , or humoral . due to the inconsistencies of endomyocardial biopsies , the existence of bnr is questioned .
this argument is furthered by the fact that prior to the 2010 amr consensus conference , 1020% of cardiac allograft recipients were diagnosed with bnr when in actuality the majority of patients most likely experienced amr .
this brings up the question of whether bnr should exist as a separate category of rejection or is merely a by - product of the problems inherent with endomyocardial biopsies . in one case study ,
sampling error or nonuniformity of histopathologic changes resulted in a false - negative biopsy . in this case study ,
a heart transplant recipient with repeatedly unremarkable endomyocardial biopsies and a negative evaluation for humoral rejection was found to have severe subepicardial myocyte necrosis with classic cellular rejection in the subsequent autopsy .
this is contrary to other studies which have found that rejection is evenly distributed throughout the right ventricular endomyocardium .
although endomyocardial biopsy is the primary resource to diagnose acute rejections in all the cases discussed in this study , there are a few noninvasive diagnostics that have been demonstrated to be helpful in diagnosing acute allograft rejection after heart transplantation . in one multicenter clinical trial , pham et al .
reported that using gene - expression profiling to monitor rejection for patients 6 months after heart transplantation was not associated with increased risk of serious adverse outcomes and could reduce the need for biopsy . in two pilot studies , wu et al .
applied cardiac magnetic resonance ( cmr ) in vivo to detect immune - cell infiltration at sites of rejection by monitoring macrophages .
the investigators subsequently developed a functional index from local strain analysis and proved it to be correlated with rejection grades [ 8 , 9 ] .
although clinical applications have not been implemented , cmr was demonstrated to be capable of providing the rejection status of whole - heart perspective , and thus might be a potential tool of optimizing diagnosis of bnr .
another potential tool is speckle - tracking 2-dimensional strain echocardiography ( 2dse ) . by using rat cardiac transplantation models , pieper et al
. demonstrated that 2dse was able to differentiate myocardial function between rejection in allografts and nonrejection in isografts .
perhaps bnr is another form of amr but due to the  newness  of amr and the lack of a complete understanding of amr , no definite conclusions can be made . despite the ishlt revised biopsy rejection scale ,
this revised definition of bnr has been noted to result in a decrease in 3-year subsequent survival , lower subsequent freedom from cardiac allograft vasculopathy ( cav ) , and a decrease in freedom from nonfatal major adverse cardiac events ( nf - mace ) .
previous studies characterized bnr as occurring on average 43  38 months following transplantation while the data collected in our study indicates that the time to the first incidence of bnr is 7.8  7.5 months . the mechanism associated with bnr
unfortunately not too many reports in the field looked at the treatment protocols for bnr . in our single center experience , who patients presented with heart failure symptoms
were given more aggressive treatment , that is , atg , iv methylprednisolone , and ivig while patients without heart failure symptoms were mostly given prednisone bolus and taper only . as bnr is an infrequent phenomenon , of which there is considerable debate regarding its validity , further work needs to be instigated on whether there is a correlation between different factors and bnr episodes .
overall , from this set of data , it is inconclusive as to whether or not there are any characteristics of bnr that differs from other types of rejections .
a point of interest in this study is the patient who experienced two episodes of bnr . due to the small sample size , it is uncertain whether having one episode of bnr increases the risk of recurrent bnr episodes . during the first bnr episode ,
in contrast , it took the patient 6 months to experience a return to normalized lvef ( 51% ) during the second bnr episode .
for the first episode of bnr , there was a favorable return to normal cardiac function following treatment with oral corticosteroids bolus and taper .
in the case of the second episode of bnr , ivig was given instead which led to an increase in lvef , although it took a longer time ( 6 months ) for the patient to experience a return to the range of normalized lvef .
prior to experiencing normalized lvef the patient 's lvef remained in the 40% range , fluctuating between 43% and 48% .
the repeat bnr patient was the only african americans in this study and did not experience normalized lvef at 90-day after second onset .
african americans have been reported to have a higher risk of rejection after transplant compared to any other race due to their unique metabolism in regard to immunosuppression [ 14 , 15 ] .
a possible immunosuppression regimen with respect to bnr could require more aggressive treatment , employing the use of atg and ivig in addition to steroids .
potential cause for this second onset of bnr could be the combined factor of this patient not receiving an adequate treatment for the second bnr and the ethnicity of the patient . as cases of bnr tend to respond favorably to appropriate rejection therapy 2 ( 17% ) of 12 bnr cases required inotropes and 7 ( 58% ) bnr cases without heart failure symptoms were treated with oral steroid bolus and taper .
seven of 12 ( 58% ) treated bnr cases resulted in a return to a normal lvef of 57%  6% within a mean of 14  10 days from the initial negative biopsy . due to the small sample size , it is uncertain whether bnr should be considered as a new category in the biopsy grading scale or if it is merely difficult to diagnose based on endomyocardial biopsies alone . if it is the former , then mechanism needs to be elucidated .
if it is the latter , then perhaps other methods for detecting rejection need to be considered .
bnr is a rare phenomenon ( 12 cases of bnr in a 10-year period ) and can be a severe form of rejection in that there is cardiac dysfunction .
however , this type of rejection is not apparent on biopsies due to either lack of knowledge regarding further types of rejection or other factors . characteristics of these cases of rejection are described above with most cases responding favorablly to rejection therapy .

Answer:
purpose .
 the most recent international society for heart and lung transplantation ( ishlt ) biopsy scale classifies cellular and antibody - mediated rejections . however , there are cases with acute decline in left ventricular ejection fraction ( lvef  45% ) but no evidence of rejection on biopsy .
 characteristics and treatment response of this biopsy negative rejection ( bnr ) have yet to be elucidated . methods . between 2002 and 2012
 , we found 12 cases of bnr in 11 heart transplant patients as previously defined .
 one of the 11 patients was treated a second time for bnr .
 characteristics and response to treatment were noted .
 results .
 12 cases ( of 11 patients ) were reviewed and 11 occurred during the first year after transplant .
 8 cases without heart failure symptoms were treated with an oral corticosteroids bolus and taper or intravenous immunoglobulin .
 four cases with heart failure symptoms were treated with thymoglobulin , intravenous immunoglobulin , and intravenous methylprednisolone followed by an oral corticosteroids bolus and taper .
 overall , 7 cases resulted in return to normal left ventricular function within a mean of 14  10 days from the initial biopsy .
 conclusion .
 bnr includes cardiac dysfunction and can be a severe form of rejection .
 characteristics of these cases of rejection are described with most cases responding to appropriate therapy .


Question:
You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
heterogenous vancomycin intermediate staphylococcus aureus ( hvisa ) strains have been reported as indicators for reduced vancomycin susceptibility in s. aureus , and various studies associated its presence with vancomycin treatment failure .
it has been shown that methicillin resistant s. aureus ( mrsa ) has the propensity to evolve into hvisa phenotype during in vitro exposure to subinhibitory concentrations of vancomycin . during the last decade
, hvisas had been isolated in many countries including those in south east asia ; nevertheless , in our knowledge , its emergence has not been reported in malaysia . as a pilot study
, we investigated the prevalence of hvisa among mrsa strains isolated at hospital kuala lumpur ( hkl ) in a 3-month period and determined factors associated with its infections .
hospital kuala lumpur is the largest hospital in malaysia with the highest mrsa burden in the country . in this hospital
, vancomycin is used as the standard first line treatment for mrsa infection ; however , recently , its efficacy has been a subject of discussion due to several anecdotal vancomycin treatment failure cases in hospital kuala lumpur .
we also wondered if some of the mrsas isolated in the hospital were actually hvisas with reduced susceptibilities to vancomycin that could not be detected by routine microbiological tests used in our hospital diagnostic laboratory . to investigate this , from 25 february to 25
may 2009 , we collected a total of 320 index mrsa isolates ( first mrsa isolated from the corresponding patients ) and established them as strains for vancomycin resistance testing . as it is cost , time and labor consuming to perform vancomycin population analysis on all 320 strains to test for heterogenous vancomycin resistance , strains were first screened for the phenotype using glycopeptide resistance detection ( grd ) etest antibiotic strips ( ab biodisk , sweden ) .
after grd screening , a total of 8 strains were defined as presumptive hvisa , no visa strain was detected . following that , to confirm the results of the grd screening
interestingly , area under the curve ( auc ) analyses of the strains ' population analysis profiles confirmed that 7 out of the 8 tested strains were hvisa ( table 1 ) , giving a prevalence rate of 2.19% .

table 1heterogenous vancomycin intermediate staphylococcus aureus strains and their corresponding patients in this study.specimen noagegenderprimary diagnosisspecimendiabetes mellitusrenal failuremalignancyadmission to icudays of hospital staydays of iv vcmon beta - lactamarea under curve ratio68214maleright hip osteomyelitisnasal swabnononoyes44 days0yes0.9058253femaleleft diabetic foot ulcerpus swabyesyesnoyes52 days14yes0.9318258maleacute ventriculitiscsfyesnonoyes98 days14yes1.0125220malegluteal sarcoma with hapsputumnonoyesyes24 days10yes0.9097871malepemphigus folliaceouspus swabyesnonono34 days7yes1.012154femaleacute encephalitis with haptracheal aspiratenononoyes32 days14yes0.9646029femalemeningo - encephalitis with hapsputumnononoyes38 days10yes0.98icu , intensive care unit ; iv , intravenous ; vcm , vancomycin ; csf , cerebrospinal fluid ; hap , hospital acquired pneumonia .

icu , intensive care unit ; iv , intravenous ; vcm , vancomycin ; csf , cerebrospinal fluid ; hap , hospital acquired pneumonia .
all hvisa strains isolated in this study were hospital acquired as they were isolated from their corresponding patients after 48 hours of hospital admission . to determine factors associated with the 7 hvisa infections , demographic data of all corresponding patients of each index mrsa isolate were retrieved from medical records .
medical history of each patient such as diabetes mellitus , renal failure , malignancy , together with prescription history of vancomycin and beta - lactam antibiotics ( as these were the only classes of antibiotics prescribed to the corresponding patients of the study isolates during this investigation ) , length of hospitalization and intensive care unit ( icu ) admission were recorded .
continuous variables were then assessed by independent samples t - test , while categorical variables were analyzed using pearson 's chisquare .
calculations were performed using statistical package for social science ( spss ) 12.0 ( spss inc . , chicago , usa ) where a p - value of < 0.05 was considered as significant . after performing multivariate linear regression
, we found that icu admission ( p<0.004 ) , hospitalization of more than 14 days ( p<0.014 ) and vancomycin administration of more than 7 days ( p<0.016 ) were independent factors associated with hvisa infections in our group of patients .
our findings were in line with those of charles et al . in 2004 , where hvisa / visa infections were found to be associated with longer antibiotic treatment periods and longer hospitalization . in a separate report
it seems that patients who are severely ill , hospitalized for long durations with icu admissions might have a higher chance of developing hvisa infections .
as many patients in hkl fulfill some or all of the above criteria , taking it together , we suspect that the prevalence of hvisa in hkl might be high ; however , these strains are not being actively detected by the hospital diagnostics laboratory .
as hvisa and mrsa with reduced vancomycin susceptibility has been reported to cause treatment failure , given the hvisa prevalence rate detected in this study , it is not surprising that vancomycin treatment failure cases among mrsa infected patients are increasing in hkl . in our study
, we employed the grd test as a screening tool for hvisa before confirming the resistance with population analysis , and found that the grd etest was fairly specific with only one false positive result .
in a review , howden and colleagues have reported the test 's sensitivity as 9394% with a 8295% specificity for hvisa detection .
therefore , the grd might be considered a good screening tool for hvisa in hospitals where most hospitalized patients are severely ill with long hospitalization durations . once identified as hvisa infected ,
optimal treatment could be prescribed to the corresponding patient to prevent vancomycin treatment failure , thereby increasing the chance of a good clinical outcome for the patient .
as the strains used in this study were collected in a short span of 3 months , and that vancomycin treatment failure is on the rise in hkl , we suspect that the actual prevalence of hvisa in this hospital might be even higher .
we found the grd test useful for hvisa screening , nevertheless pap - auc analysis still remains the gold standard for hvisa confirmation .
a more comprehensive , case control study involving major hospitals in the country would be important to better understand the significance and distribution of hvisa in malaysian hospitals .

Answer:
in a 3-month study done in hospital kuala lumpur ( hkl ) , 7 out of 320 methicillin resistant staphylococcus aureus isolates were confirmed as heterogeneous vancomycin intermediate s. aureus ( hvisa ) using the glycopeptide resistance detection e - test and population analysis , giving a prevalence rate of 2.19% .
 this is the first report of hvisa in malaysia .


Question:
You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
the cross - sectional study was undertaken in the schools located within the registered rural and urban field practice areas of the department of community medicine , jnmc , aligarh , uttar pradesh , india .
the total population of male adolescents ( 10 - 19 yrs ) in all the schools was 2347 , out of which a sample of 410 students ( 205 from the rural schools and 205 from the urban schools ) were selected using probability proportionate to size sampling ( pps ) .
the sample size was calculated using the formula , sample size = ( 1.96 ) pq /
l where prevalence ( p ) = 20% , q = ( 1p ) precision ( l ) = 4% the study tools consisted of a self - developed , pre - tested , semi - structured questionnaire arranged in two parts .
the first part of the questionnaire dealing with the child 's sociodemographic background was accomplished by the interviewer , and the second part had a section of aspirations and desires of adolescents including their role models and their future choice of career .
all participants were reassured about their anonymity by instructing them to avoid writing their names and class section on the questionnaires .
socioeconomic class was calculated using a modified form of prasad 's classification of per capita income .
simple percentages [ table 1 ] and chi - square test of statistical significance was used for analysis [ tables 2 and 3 ] .
sociodemographic characteristics role models of in - school adolescents occupational aspirations of in - school adolescents
most of the study population was in their early ( 10 - 13 yrs ) and mid - teens ( 14 - 15 yrs ) , hindu , lower to middle socioeconomic status , and living in unitary families with more than 5 family members [ table 1 ] .
adolescents responded to the question regarding the presence of a role model in their lives with a near total majority ( 95.9% ) .
overall , the majority ( 62.7% ) of adolescents revealed that their role models were film star ( 34.8% ) and their teachers ( 27.9% ) , parents ( 14.3% ) , sportsman ( 12.0% ) .
politicians as the role models were opted by least proportion ( 1.2% ) . in urban and rural schools ,
there were significant differences between the choices of the role models ( chi - square = 24.1 , df = 06 , p < 0.05 ) [ table 2 ] . when asked about the desires for the future occupation or job
, many adolescents ardently responded that they wish to become businessmen ( 27.9% ) , doctor ( 18.6 ) , and engineer ( 14.4% ) .
others opted to be a teacher , farmer , police officer , or government servant .
the difference between urban and rural adolescents in the occupational desires was statistically significant ( chi - square = 18.9 , df = 08 , p < 0.05 ) .
most of the study population was in their early ( 10 - 13 yrs ) and mid - teens ( 14 - 15 yrs ) , hindu , lower to middle socioeconomic status , and living in unitary families with more than 5 family members [ table 1 ] .
adolescents responded to the question regarding the presence of a role model in their lives with a near total majority ( 95.9% ) .
overall , the majority ( 62.7% ) of adolescents revealed that their role models were film star ( 34.8% ) and their teachers ( 27.9% ) , parents ( 14.3% ) , sportsman ( 12.0% ) .
politicians as the role models were opted by least proportion ( 1.2% ) . in urban and rural schools
, there were significant differences between the choices of the role models ( chi - square = 24.1 , df = 06 , p < 0.05 ) [ table 2 ] .
when asked about the desires for the future occupation or job , many adolescents ardently responded that they wish to become businessmen ( 27.9% ) , doctor ( 18.6 ) , and engineer ( 14.4% ) .
others opted to be a teacher , farmer , police officer , or government servant .
the difference between urban and rural adolescents in the occupational desires was statistically significant ( chi - square = 18.9 , df = 08 , p < 0.05 ) .
this study highlighted that majority of adolescents have a personality in their minds , whose attributes they follow in their life .
though the stage of adolescence is a dynamic period of life with respect to changing attitudes and perceptions , change in their role models might be seen in due course with increasing age and maturity . at
any given phase of adolescence , their choice of role models may indicate the likings and behavior form of the adolescent . an adolescent may choose a particular role model due to a bouquet of reasons . in this study , the reason given by the majority was related to the image of being ideal with a virtue of righteousness along with the glamour attached to them .
this reason may be an indication of choosing film stars as the role model as this virtue is usually shown in the heroes of indian films .
a good teacher also leaves a good impact on the students ; thus , a good proportion chose them as role models .
a small proportion chose parents as role models ; the reasons for this observation need a detailed study . according to a researcher , in their study of adolescents from rural area it was found that film heroes were the role model for 31.3% students , cricketers for 12.61% , and political leaders for 7.83% students and for the rest of the students , parents / teachers were the role models .
the pattern of choice was similar as compared to the present study . in another study , fifty - six percent of adolescents identified a role model .
parent / relative ( 42% ) , non - familial known individual ( 19% ) , and  figure  or individual available primarily through the media ( 39% ) . among non - familial known individuals were friends ( 56.9% ) , professionals such as doctors or lawyers ( 22.8% ) , teachers ( 15% ) , and clergy ( 1.2% ) . among
figure  were actors ( 18.5% ) , historical figures ( 5.7% ) , political leaders ( 1.9% ) , comic book characters ( 1.2% ) , and a community leader ( 0.6% ) .
the desire of future occupation during adolescent plays an important role in the academic journey of an individual .
often , it has been observed that putting a foot in wrong shoe is detrimental to the practical life of an individual .
the mindset of the society regarding various professions puts an enormous pressure on the adolescents .
further , the ever - increasing competition for some professions also augments the bulk of non - achievers of the competition and leaves them with disappointment and depression .
professionally guiding adolescents according to their likes and dislikes regarding their career could bring down the proportion of otherwise non - achievers . in a study , in response to the question ,  if you had to start work tomorrow and assuming you had the proper education or training , what kind of work would you most likely choose ?  , the following seven themes emerged from the responses of grade seven students : ( a ) professional occupations ( e.g. lawyer , computers , doctor , nurse , architect , counselor ) ; ( b ) glamour occupations ( e.g. athlete , actress , fashion designer , chasing tornadoes ) ; ( c ) trade occupations ( e.g. mechanic , carpenter ) ; ( d ) occupations with children ( e.g. daycare worker , teacher ) ; ( e ) occupations with animals ( e.g. zoologist , wildlife biologist , veterinarian ) ; ( f ) volunteer occupations , and ( g ) service industry occupations ( e.g. chef , bed and breakfast , hairdresser ) . the finding of present study is in accordance with the above - mentioned study as the students revealed various choices for the future profession . in another study , the students who wanted to become doctor were 23.48% , engineer 16.5% , and teacher 24.54% , 14% students wanted to join defense / police services and the rest wanted to join the business / salaried jobs .
the reason may be that the majority of study population belonged to the rural area where agriculture and small scale business was more practiced .
it is observed in this study that although the role model in good proportion of adolescent were film stars , only 2 students desired to be an actor .
this observation highlights that the students had rational thinking when it comes to future occupational choices .
the above - mentioned studies show that the career choices during adolescent are varied , and all they need is proper guidance to progress with their choice of profession and they might give best results according to the developed capacity in them rather than being depressed .
there is greater impact of cinema on the minds of adolescents , which resulted in choosing film actors as their role model .
the choice of future occupation was not related to the type of role models but may be influenced by society and family admiration for certain occupations .
proper guidance in this phase of life in needed to develop rational thinking in adolescents .
the permission of this thesis survey was obtained by the institutional board of studies held on 20.08.2002 .
verbal consent of the principals of the schools selected for the study was received prior to starting the study .
the parents of the students were informed about this study in the parent teacher meeting and their consent was obtained by the principal of the school .

Answer:
background : a role model is perceived as worthy of imitation , their selection can indicate significant elements of psychosocial health and self - projection in adolescents . patterns of behavior and lifestyle choices established during adolescence can have immediate and lasting effects on health.materials and methods : cross - sectional study was undertaken in the schools of aligarh , uttar pradesh , india .
 the sample frame was 2347 , out of which a sample of 390 students was studied .
 data collected were entered and analyzed by spss for windows version 10%).results : majority ( 62.7% ) of adolescents revealed that their role models were film star ( 34.8% ) and their teachers ( 27.9% ) , parents ( 14.3% ) , sportsman ( 12.0% ) .
 politicians as the role models were opted by least proportion ( 1.2% ) .
 desire of future occupation was businessmen ( 27.9% ) , doctor ( 18.6 ) , and engineer ( 14.4%).conclusion : nearly all adolescents had a role model .
 there is greater impact of cinema on the minds of adolescents , which resulted in choosing film actors as their role model .
 aspiration of future occupation was not related to the characteristics of the role model .


Question:
You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
children constitute approximately 40% of india 's population but information on adverse drug reactions occurring in them is limited .
phenytoin sodium ( pht ) is one of the commonest antiepileptic drug ( aed ) used in children in india .
the drug has wide pharmacokinetic variability and has a narrow therapeutic range that leads to toxicity .
there is some evidence of the association of long - term use of pht and toxicity like cerebellar atrophy .
such cerebellar changes have been reported even with the long - term use of nontoxic levels of phenytoin .
, we report a case of reversible cerebellar atrophy induced by pht in a 10-year - old boy .
after initiating therapy with pht 10 years back , he was seizure free for 2 years .
patient was also occasionally prescribed clobazam , 5 mg , oral , as and when required . the episodes used to last for a brief period of over 6 - 7 days .
seizures used to occur at every 3 - 4 months interval . the boy had history of birth asphyxia and delay in developmental milestones .
after the patient recovered , he was evaluated again due to complaint of difficulty in walking .
cns examination revealed normal mentation with cerebellar signs including gaze - evoked nystagamus , truncal , and appendicular ataxia .
mri scan of the brain was advised and it showed cerebellar atrophy as shown in figure 1 .
serum phenytoin level was high ( 30 mcg / ml ) and pht was withdrawn immediately . patient was started on valproic acid and followed up .
however , a sizeable proportion of patients may develop drug induced adverse effects that include sedation , gum hypertrophy , lymphadenopathy , chorea , ataxia , etc .
there are a few reports on cerebellar atrophy after long - term use of pth .
these adverse effects are usually reported if the drug serum levels are above the therapeutic range .
our patient presented with severe cerebellar disorder and he was on the drug for 10 years .
hence , a regular monitoring for adverse drug reaction should be considered in patients who are on drugs on long term basis .
these reactions could be idiosyncratic or dose - dependent which again may be acute or chronic in nature .
since most of these effects are reversible , it is important to identify the clinical manifestations related to drug toxicity and to manage them appropriately . also , it warns the need for regular monitoring of plasma concentration , accurate dosing , and identification of adherence issues in patients on phenytoin .

Answer:
epilepsy is an important health problem due to its high prevalence and potential for causing long - term morbidity .
 it is commonly treated in children with phenytoin sodium .
 it has wide pharmacokinetic variability and a narrow therapeutic range that leads to toxicity . here
 , we report a case of phenytoin - induced cerebellar atrophy in a 16-year - old epileptic boy who presented to the hospital with a viral infection .


Question:
You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
posterior elbow dislocation is the most common type of elbow dislocation with slightly higher incidence in the male population and they constitute 1025% of all injuries to the elbow among persons with a mean age of 30 years .
the human instinct to protect the dominant arm from injury during fall is responsible for a slight predominance for dislocation in the nondominant extremity .
a high index of suspicion should be maintained by the emergency physician in evaluation for neurovascular compromise in all cases with elbow dislocation , especially in cases where the x - ray is normal . in most of the times ,
a simple lateral view x - ray shows the dislocation , and absent radial and ulnar pulses insures that an arterial injury is present . in our case , the x - rays were normal , and the patient had normal pulses on presentation .
a 71-year - old right - handed male presented to our emergency department ( ed ) with left elbow pain after he fell on his left outstretched hand 1 h prior to presentation .
physical examination revealed a swollen elbow , with a dusky cold hand ; radial and ulnar pulses were initially felt and were weak in comparison with the contralateral side , but after repeated assessment , the pulses became absent .
radiographs revealed no fracture or dislocation of the elbow joint ( fig .  1 ) .

figure  1:posterior splint was applied in ed and x - rays showed no fracture , no dislocation .
posterior splint was applied in ed and x - rays showed no fracture , no dislocation . as arterial injury was suspected , angiography was done and revealed a brachial artery occlusion proximal to its bifurcation with the presence of some collateral circulation reaching and perfusing the radial and ulnar arteries .
intraoperatively , the elbow was found to be grossly unstable and easily dislocatable especially on extension .
access to the brachial artery was achieved via a lazy s incision across the antecubital fossa , and exploration revealed brachial artery contusion , with intact adventitia and median nerve ( fig .  2 ) .

figure  2:intact adventitia of the brachial artery ( arrow ) , also the median nerve seen stretched over the articular surface of the distal part of humerus , is intact ( scissors ) .
intact adventitia of the brachial artery ( arrow ) , also the median nerve seen stretched over the articular surface of the distal part of humerus , is intact ( scissors ) .
the anterior elbow capsule was disrupted associated with avulsion of the flexor pronator group from the medial epicondyle .
as arteriotomy was done , there was an intimal loss over the entire arterial circumference for 1 cm ( fig .
figure  3:loss of intima in all the entire circumference of the brachial artery in a 1-cm segment ( arrow ) .
loss of intima in all the entire circumference of the brachial artery in a 1-cm segment ( arrow ) .
the defective part of the artery was excised and repair was achieved by placement of a brachiobrachial end - to - end reversed saphenous bridge ( fig .  4 ) .
the time of trauma - to - revascularization was 7 h ; primary wound closure was performed without prophylactic fasciotomies .

figure  4:complete arterial repair using an end - to - end reversed saphenous bridge .
radial and ulnar pulses were regained directly postoperatively together with a normal color and warmth of the upper extremity , vascular observation was done to rule out compartment syndrome . in the postoperative period ,
the elbow was immobilized for 3 weeks with a posterior splint in 70 flexion , then active range of motion exercises was started . at 1-year follow - up ,
patient regained all activities , and had nearly full range of motion , but with 15 loss of extension .
the frequency of vascular involvement associated with closed elbow dislocation remains difficult to establish because the literature only reports short series of sporadic case studies , it approaches 4.3% , and in some series , as low as 0.47% reported by spark et al .   who had 3 cases of vascular injury out of 634 closed elbow dislocation .
while reviewing the literature , we found only one case of brachial artery injury that was reported in the middle east and was treated conservatively .
this leads us to the fact that these types of injuries are either missed because of collateral circulation or underreported due to the lack of research and proper documentations .
whenever there is a suspicion of arterial damage , angiogram should be performed immediately and it still considered the gold standard for evaluation of arterial injury . sparks et al .
reported that only 12 of 30 cases of closed dislocation investigated for arterial insufficiency by angiography had arterial injuries .
having a positive pulses do not rule out brachial artery injury as patient can have a well - developed collateral circulation around the elbow . in our case ,
patient first had a weak pulse , then it became absent , and this could be explained by two theories .
first , an intact collateral circulation perfusing the radial and ulnar arteries   and with ongoing elbow swelling , these collaterals were gradually compromised leading to impaired blood flow , and fading of the pulses .
secondly , it can be explained by the fact that the initial injury caused only an intimal injury , that was not sufficient to cause a complete brachial artery occlusion , but an ongoing thrombosis formation on top of the intimal injury was occluding it gradually .
although radiograph with lateral view of the elbow shows clearly a dislocation when present , most of the spontaneous reduction can be misleading and the injury will be overlooked .
only two cases of occult elbow dislocation with vascular injury were reported in the literature , and in both cases , there was a complete rupture of the brachial artery .
few are the cases of intimal injury associated with elbow dislocation causing acute limb ischemia , in comparison with complete arterial transection ; due to the rarity of the condition , few are the articles showing the prevalence of this type of arterial injury . concerning the management , it is now generally accepted that the standard of care is repair or reconstruction of a brachial artery injury .
to our knowledge , the combination of occult elbow dislocation with intimal injury of the brachial artery in a 71-year - old male makes this case to be the first reported in the literature . in conclusion , palpable pulses after elbow dislocation should not rule out arterial injury and arteriogram should be done in case of suspicion of vascular injury as it is the gold standard of diagnosis in these injuries .
normal radiographs as they show only the position of the joint at the time the radiographs was taken , and not the time of injury .
if the clinical picture is in out of proportion with the x - ray findings , the case should be dealt with caution , and further investigations should be done .

Answer:
posterior elbow dislocation with vascular injury is rarely encountered , but it is crucial for every emergency physician to diagnose it .
 missing these injuries can result in neurovascular compromise , which in turn can lead to limb ischemia , compartment syndrome and potential limb loss .
 having a normal x - ray on presentation makes this injury more difficult to diagnose . in this study , we present a case of occult posterior elbow dislocation with an intimal injury of the brachial artery .
 the rarity of these cases , the diagnostic modalities and the treatment options will be reviewed .


Question:
You will be shown the title of a chemistry paper, together with sections excerpted from the body of the paper. The paper sections may include HTML tags like `<p>` and `</p>`; please ignore these. Your task is to write an abstract for the paper. Your response should include the abstract and no other text.

Title:
Nucleophilic Aromatic Substitution, A Guided Inquiry Laboratory Experiment

Paper sections:
Introduction

"How to extract knowledge from experimental results is at the heart of science, yet for the most part we don't attempt to teach this skill in traditional labs [1]." Recently, there has been significant interest in addressing this missing element in the curriculum. Inquiry-based laboratory experiments are a form of active learning that has the potential to enhance the student's critical thinking and analytical skills. We have applied this pedagogical concept to a traditional organic reaction, the N-arylation of aniline derivatives. The reaction is a practical way to introduce nucleophilic aromatic substitution into the undergraduate organic chemistry laboratory. There is also an expectation that the experiment will encourage students to see the connection between concepts and will give them the opportunity to constructively challenge what they know. Providing such an opportunity for reflection will enhance the intellectual climate of the organic chemistry course.

Often, the topic of nucleophilic aromatic substitution is presented with primary emphasis on the benzyne mechanism (Scheme 1), but with less discussion than is given to electrophilic aromatic substitution. Under the framework of inquiry-based learning, a straightforward laboratory procedure has been developed that focuses on the addition-elimination mechanism, Scheme 2. The experiment can be presented as an exploration of the trends in reactivity for the electrophile. Students are encouraged to draw upon their fundamental knowledge of chemical bonds and use that information to develop conclusions relating to the kinetic characteristics of the reaction. By doing so, students apply previously learned lecture concepts (i.e. resonance effects, nucleophilicity, leaving group trends, characteristics of polar covalent bonds, etc.) to the interpretation of laboratory results. In addition to promoting critical thinking, the experiment incorporates techniques such as acid/base extraction, microwave assisted organic synthesis (MAOS), TLC, HPLC, and IR.

The results obtained in this experiment differ from what students will expect for leaving group ability; but, the results do coincide with what is understood for polar covalent bonds. This provides an opportunity for the students to develop new knowledge through the logical and constructive discussion of results. Therefore, the experiment will reinforce useful laboratory techniques and instrumental methods while exposing the students to critical thinking in the analysis of data.

The preparation of (2-nitrophenyl)arylamines (3) has been well-studied utilizing traditional heating methods and organometallic reagents [2–5]. Nevertheless, many of these reactions require long reaction times and tedious extractions while producing only modest yields [3, 6]. The recent emergence of microwave assisted organic synthesis (MAOS) has created new opportunities for improving reaction conditions and outcomes. One such procedure has been adapted for the N-arylation of an aniline derivative. The reaction utilizes stoichiometric equivalents and is conducted under microwave irradiation, Scheme 3. The MAOS procedure employs an inexpensive basic clay (KF/K2CO3 in the reaction shown) to generate heat in the reaction, which proceeds without the use of solvents or organometallic reagents. Often, the procedure results in the complete conversion of the starting material to product.

Overview of the Experiment

The N-arylation of toluidine is used to represent the nucleophilic aromatic substitution. Since the reaction can be completed in less than 15 minutes, there is sufficient time for the extraction and the HPLC analysis of the reaction outcome in one class period. Therefore, the procedure was adapted to create a facile undergraduate laboratory experiment that is safe and can be repeated in the same laboratory setting if necessary. Our modified procedure does not give complete conversion of starting material to product. However, TLC of the final reaction mixture shows that only starting compounds (1 and 2) and the desired product (3) are present. When this mixture is washed with a 10% solution of HCl, the TLC shows that only the substituted nitrobenzene (1) and the product (3) are present in the organic layer. Subsequently, the mixture is analyzed by HPLC. If an HPLC is not available, the experiment can be conducted over two lab periods to allow the isolation of the product by column chromatography.

Consider what is known about polar covalent bonds. How does the electronegativity affect bond strength? Is this knowledge consistent with your results?

Based on your results and your answer to question 1, what is the connection between bond strength and leaving group ability?

What is the relative trend of leaving group ability in SNAr reaction?

What is the effect of electronegativity of the leaving group on the reactivity of the electrophile?

How does the electronegativity of the leaving group affect the ability of the reaction to take place?

Overview of the Experiment

The questions are purposely interrelated and model for the students how the results should be interpreted at various levels of inquiry. Collectively with the mechanism, the interpreted HPLC results aid the students in discussing how the electronegativity of the leaving group affects the rate of the reaction.

Procedure

The aniline derivative (0.25 g, 1 equiv) along with potassium fluoride (1 equiv) and potassium carbonate (1 equiv) are made into a powder using a mortar and pestle. The mixture is transferred to a vial. 2-fluoronitrobenzene (1 equiv; 1a–c) is added to the mixture and thoroughly mixed with a glass rod. Then the mixture is placed in the microwave (CEM MSP 1000, 100W, 160 °C) for 10 minutes [7]. The mixture is allowed to cool for 10 min. Water (10-mL) is added and the mixture is extracted into ethyl acetate (3 × 15-mL). The ethyl acetate solution is then washed with a solution of 10% HCl followed by a solution of saturated Na2CO3. The organic layer is dried over anhydrous sodium sulfate and analyzed by HPLC to determine the relative yield of the reaction (ration of starting material to product present in the mixture). The TLC analysis of the ethyl acetate layer is conducted utilizing silica plates with UV indication and 20% ethyl acetate/80% hexane as the developing solvent.

Discussion

Successful completion of the experiment using 2-halo substituted nitrobenzenes illustrated the following trend in increasing leaving group ability: Cl < Br < F. Since electrophilicity can be directly related to leaving group ability, it can be observed in this experiment that by using the fluoro substituted nitrobenzene the reactivity of the electrophile will be increased. Based on this, the experiment indirectly illustrates how the electronegativity of the leaving group affects bond strength (the highest reaction yields are obtained when the bond between the leaving group and the ring is weakest). The results of the reaction can lead to further discussion relating to the polarization of bonds, aromaticity, and inductive effects.

Conclusion

We have developed a microwave procedure that is a good illustration of the reaction between the aryl halide and the aniline derivative. The nucleophilic aromatic substitution reaction gives results that can be used to guide students understanding of basic organic trends surrounding the reaction. The newly developed laboratory module will contribute to the growing collection of inquiry-based activities that are available for organic chemistry. This procedure can be modified to include experiments relating to the reactivity of the nucleophile that will also be suitable for the undergraduate curriculum. In addition, the experiment reinforces key skills and instrumental techniques (TLC, HPLC, acid/base extraction). With the additional points of inquiry, the experiment would be excellent for use as a standalone experiment or capstone project.

List of possible electrophiles

Answer: Inquiry-based learning is a unique student-centered alternative to traditional instruction. This form of active learning is ideal for the organic chemistry laboratory as it encourages critical thinking and hands on problem solving to complete an experiment. Electrophilic Aromatic Substitution is immediately associated with the undergraduate organic chemistry course. However, nucleophilic aromatic substitution is not. The N-arylation of aniline derivatives is a useful reaction for implementing nucleophilic aromatic substitution into the undergraduate curriculum. Under the framework of inquiry-based learning, a straightforward procedure has been developed for the undergraduate laboratory. This experiment explores the reaction rate of the nucleophilic aromatic substitution using various electrophiles. The reaction is conducted under microwave irradiation and the experiment is completed in one laboratory setting.


Question:
You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
the roots of zapoteca portricensis is a common remedy in the treatment gastrointestinal disorders used by tradomedical practitioners in eastern nigeria .
this study was aimed at evaluating the possible antiulcer activity of the root of this plant in experimental rats .
different groups of albino rats of male sex were given three doses ( 50 , 100 , 200 mg / kg ) of the extract .
the ethanol model produced an average ulceration in rats with reduction of ulcer ( 50% , 75% and 90% ) seen in all the extract treatment .
a dose dependent inhibition of ulcer was seen in all doses of the extract with doses 100 and 200 mg / kg produced a significant reduction compared with control . in the indomethacin model ,
inhibition of ulcer ( 57.1% , 65.7% and 80.0% ) was seen in the treatments with the extracts in a dose dependent manner .
this study has shown that roots of this plant ( zapoteca portoricensis ) possess potent antiulcer activity .

Answer:
background : the roots of zapoteca portricensis is a common remedy in the treatment gastrointestinal disorders used by tradomedical practitioners in eastern nigeria.aim:this study was aimed at evaluating the possible antiulcer activity of the root of this plant in experimental rats.methods:a methanolic root extract was prepared by cold maceration .
 antiulcer activity was tested using absolute ethanol and indomethacin induced ulcer models .
 sucralfate ( 100 mg / kg oral ) was used as the reference drug .
 different groups of albino rats of male sex were given three doses ( 50 , 100 , 200 mg / kg ) of the extract .
 phytochemical analysis of the freshly dried roots was also done.results:phytochemical results revealed presence of alkaloids , terpenoids , glycosides and flavonoids .
 the ethanol model produced an average ulceration in rats with reduction of ulcer ( 50% , 75% and 90% ) seen in all the extract treatment .
 a dose dependent inhibition of ulcer was seen in all doses of the extract with doses 100 and 200 mg / kg produced a significant reduction compared with control . in the indomethacin model ,
 an absolute ulceration was produced in all the animals .
 inhibition of ulcer ( 57.1% , 65.7% and 80.0% ) was seen in the treatments with the extracts in a dose dependent manner .
 all the three doses of the extracts produced significant ulcer protection compared with control.conclusion:this study has shown that roots of this plant ( zapoteca portoricensis ) possess potent antiulcer activity .


Question:
You will be shown the title of a chemistry paper, together with sections excerpted from the body of the paper. The paper sections may include HTML tags like `<p>` and `</p>`; please ignore these. Your task is to write an abstract for the paper. Your response should include the abstract and no other text.

Title:
Caryophyllene as a precursor of cross-linked materials

Paper sections:
Introduction

New strategies to develop materials from renewable feedstock have been continuously sought as greener alternatives to commercial oil-based materials. There is a significant interest in polymeric materials, taking into consideration their wide range of applications, especially for elastomers. The elastomers market has witnessed significant growth in the global production in recent years, with an estimated increase in revenue from current US$ 80.73 billion to close to US$ 104.17 billion by 2026. 1,2 The adoption of vulcanized thermoplastics (TPV) in various application sectors has led to this development.

Among several categories of thermoplastics, the natural rubbers (NR) emerge as a major players. The NR segment plays an important role in the TPV global market since the NR is one of the most used thermoplastic thanks to their versatility. 2 Due to their properties such as high thermal stability, good chemical resistance, high tensile strength, low shrinkage, and greater design flexibility, they can be employed as devices and/or tools for automotive, medical, consumer goods, industrial, and other applications. 3,4 In the framework of looking for an alternative to oil-based consumer goods, an important number of research groups have concentrated their studies and described the synthesis of vegetable-oil-based thermoplastics, such as polyester, polyurethanes, polyamides, and many other bio-based polymers. [4][5][6][7][8][9][10] Terpenes and terpenoides have drawn considerable attention as potential starting precursors in the synthesis of elastomers. [11][12][13][14][15][16][17] Studies on the synthesis of elastomers from pinene, myrcene, and limonene [18][19][20][21] can be readily found in the scientific literature and some commercially available resins and adhesives (e.g. Piccolyte®) derived from polypinenes are already reported. However, there is little exploitation of sesquiterpenes by the scientific community. Among molecules defined as sesquiterpenes, caryophyllene and humulene stand out, since these molecules are made of interesting structural elements. These molecules are found in many essential oils such as rosemary, cannabis sativa, hops, and mostly clove oil. [22][23][24] The cheapest and most abundant sesquiterpene, the caryophyllene, is a versatile and significant molecule due to a bicyclic and a cyclobutane rings as well as unsaturated bonds present in its chemical structure. 23 Thanks to them, the caryophyllene can be easily modified by attaching different moieties to its backbone chain. Moreover caryophyllene is, to the best of our knowledge, the only readily available bio-based molecule that can be polymerized by ring-opening metathesis polymerization (ROMP) leading to polycaryophyllene (PCar). 25 PCar exhibits two carbon-carbon double bonds in its structure which can be further used to cross-link it.

Keeping in mind this context, the present research has aimed to the cross-linking of polycaryophyllene by using different routes and investigating the thermo-mechanical properties of the newly produced cross-linked bio-based elastomer. Two main pathways have been considered to reach three dimensional cross-linked polycaryophyllene: i) thermal pathways: in the presence of organic peroxides [benzoyl peroxide (BPO) or dicumyl peroxide (DCP)], or by classical vulcanization based on sulfur (SS) and ii) via UV light initiated thiol-click reactions at room temperature (see diagram in Fig. 1). As far as we know, this is the first study about the cross-linking of polycaryophyllene. To confirm the crosslinking, the gel fractions were quantified by extraction in THF at 50 °C for 48 hours.

The resulted gel fractions were 65 %, 90 %, and 72% for BPO, DCP, and SS respectively, as summarized in Table 1. The gel fraction appears to be limited for BPO cross-linking at 65% since even an increase of the curing temperature to 180 °C does not improve the gel fraction (see Table S1).

Obtaining a higher amount of gel fraction with DCP compared to with BPO was already identified in other studies. 26,27 Indeed, DCP is the most frequently used cross-linking agent since it is an organic peroxide which is more selective to vinyl moieties than benzoyl peroxide. 28,29 The ability of cumyloxy radical from DCP to react with non-activated vinyl moieties in a free-radical cross-linking pathway via H abstraction may be a possible explanation of its higher reactivity compared to BPO. 30 Additionally, the cumyloxy radical can undergo β-scission resulting in radical fragments (methyl radical and acetophenone) with high mobility. 31 Furthermore, the unsaturated bonds are not easily accessible by benzoyloxy radicals due to the steric hindrance around double bonds as the increase of formation of cross-linked networks. 24 The SEC analysis of the BPO soluble fraction testified to the presence of oligomers (see Fig. S7, Mn=320 g.mol -1 , Đ=1.5) which indicated that some polymer backbone cleavage also takes place during the crosslinking. In the case of the sulfur system, the soluble fraction is mainly constituted of the accelerator and the catalyst used. Finally, the IR analysis of the materials obtained (see Fig. S8) shows that whatever the cross-linker, the vibration characteristics the carbon-carbon double bond (i.e. =CH2 bending 887 cm -1 , C=C stretching at 1645 cm -1 , C-H stretching at 3115 cm -1 ) are still present indicating a crosslinking by hydrogen abstraction mechanisms.

In order to confirm the occurrence of cross-linking reactions, on-line rheology measurements were carried out, they are shown in Fig. 2. The visco-elastic analysis also provided an estimation of the initial temperature of the cross-linking process. As expected, polycaryophyllene in the absence of a crosslinker behaves as a liquid for temperatures up to 160°C with the loss modulus (G'') higher than the storage modulus (G'). Classically, as the temperature increases, both moduli continuously decrease and no cross-linking reaction takes place at 160°C since no change in moduli was observed over time.

In the presence of DCP, a shoot up in moduli is clearly observed with a gel point (intersection point) at After the gel point, both loss and storage moduli reached constant plateaus and no more significant changes are observed. The magnitude of storage modulus increased up to 0.6, 0.5, and 0.5 kPa and the loss modulus to 1.2 MPa, 40, and 60 kPa respectively for polycaryophyllenes cross-linked by DCP, BPO, and sulfur system.

Concerning the UV cross-linking by thiol-ene coupling, the soluble fraction remains between 0% and 11% depending of the dithiol used (see Table 1). Interestingly, when the crosslinking is performed with 0.5 eq. of thiol per carbon-carbon double bond (db), a slight improvement of the gel fraction is observed (see Table S2). This may be to the presence of free dithiol in the soluble fraction. IR analysis of the polycaryophyllene obtained with 0.5 eq. of thiol per db shows no regioselectivity of the thiol-ene addition since the bands which are characteristic of the two carbon-carbon double bonds decrease (see Fig. S13).

For 1 eq. of thiol per db, double bonds appear to have totally disappeared whatever the dithiols used (see Fig. S14).

To obtain further information about cross-linked polycaryophyllenes, TGA and DSC measurements were performed in order to investigate their thermal properties, as shown in Fig. 3, Fig. 4 and Table 1.  The mechanical properties of cross-linked polycaryophyllene were evaluated by dynamic mechanical analyses (DMA), displayed in Fig. 5 and Fig. S18.

The DMA curves show a typical behavior for cross-linked materials with a glassy plateau before the alpha transition temperature (T) followed by a rubbery zone after this point. in agreement with the one obtained by DSC (12 °C, -6 °C and -9 °C respectively). Finally, the rubbery plateau confirms the cross-linking of the materials and its value is directly proportional to the cross-linking density. Polycaryophyllene crosslinked by DCP exhibits significantly higher storage modulus above glass transition temperature (27 MPa) compared to SS or BPO systems (0.7 and 0.9 MPa respectively) (see Table 1) or even DDT cross-linking (4.6 MPa).

Conclusions

In the present work, caryophyllene was polymerized by ROMP and the polymer obtained was crosslinked using different routes: organic peroxides, sulfur system or dithiol. Rheological analyses confirmed the occurrence of cross-linking reactions in agreement with the extractions by THF results. Swelling experiments showed that the polycaryophyllene was entirely cross-linked by DCP or dithiols with an insoluble fraction over 90%. Cross-linking by sulfur system resulted in a gel content of 72%.

The cross-linked materials were in-depth analyzed by TGA, DSC and DMA. Materials were obtained with Tg between -22°C and 12°C with improved thermal stability compared to non-cross-linked polycaryophyllene (T10% > 300°C). At room temperature (20°C) storage modulus of the cross-linked polycaryophyllene were between 1 MPa to 100 MPa. Based on the achieved results, they could potentially find applications as replacement of synthetic rubbers.

Answer: This paper aims at the synthesis of a new type of elastomers from caryophyllene. The adopted strategy was to cross-link the polycaryophyllene, which was synthesized by ring-opening metathesis polymerization (ROMP). The polycaryophyllene obtained showed Mn = 2 x 10 4 g.mol -1 (Đ = 1.5) with a glass transition temperature (Tg) of -35 °C. On the first hand, thermal crosslinking was performed in the presence of organic peroxides or sulfur system. On the second hand, thiol-ene coupling initiated by UVlight at room temperature was also investigated as an alternative pathway to cross-link the polycaryophyllene. The materials obtained were analyzed by TGA, DSC, and DMA. The Tg of cross-linked polycaryophyllene could be easily modulated from -35 °C to a range between -25 and 10 °C by changing the type of cross-linking agent. The curing process led to the improvement of thermal stability ranging from 200 °C to around 340 °C. Finally, the network storage modulus varied from 1 to 100 MPa at room temperature.