Low national immunization coverage (44.64%) requires strengthening the vaccination campaign to improve knowledge about HPV and its vaccine among adolescents and parents/guardians. Our aim is to evaluate factors related to knowledge about HPV, its vaccine, acceptability and divergences among Brazilian adolescents and parents/guardians.A cross-sectional study was performed at a health unit of Sao Paulo University, Brazil, from 2015 to 2016. The convenience sample comprised 1047 individuals, including 74% (n = 776) adolescents and 26% (n = 271) parents/guardians, who answered a survey .The main source of information for adolescents was school ; for parents/guardians, it was health professionals . Parents/guardians were 2.48 times more likely than adolescents to know that HPV caused changes in the Pap smear test , 1.43 times likely to be aware that HPV was a sexually transmitted infection , and 2.77 times likely to be informed that the HPV vaccine decreased the chance of having genital warts . Girls knew more about the topic than boys ; education increased parents’ knowledge .Female adolescents and parents/guardians with a higher level of education are factors related to suitable knowledge about HPV and its vaccine among Brazilian respondents. There were differences between parents/guardians and adolescents in HPV awareness, clinical implications, vaccine knowledge and vaccine acceptance. The persistence of human papillomavirus (HPV) infection is the leading cause of more than 90% of cervical cancer cases and is responsible for a significant fraction of other anogenital  and oropharyngeal cancer (60%) . CervicaThe quadrivalent HPV vaccine is a primary prevention strategy for cervical cancer. The vaccine is available in immunization programs worldwide in 64 countries including Brazil . Free acTo guarantee efficient results and reduce the instance of cervical precancerous lesions vaccination coverage with all doses should exceed 80%  of the tThere are few records in Latin American literature on adherence to the HPV vaccine after its implementation. What has been published highlights the lack of knowledge about HPV infection among Latin Americans, which is related to low education status and economic income –10. DoubThe decision-making process concerning adolescents`vaccination is influenced by parents/guardians’ lack of willingness to vaccinate their dependent ,12,14, eThe purpose of this study is to evaluate factors related to knowledge about HPV, its vaccine, acceptability and divergences among Brazilian adolescents and parents/guardians.A cross-sectional analytic study was conducted in a basic health unit linked to the Obstetrics and Gynecology Department of the Medical School of the -University of Sao Paulo, Sao Paulo State, city of São Paulo, Brazil, from 2015 to 2016 during quadrivalent HPV vaccination implementation.The convenience sample was composed of 1047 participants—Adolescents attending a public clinic and their accompanying parents/guardians made up the study sample. If teenagers arrived accompanied by more than one guardian, the guardians who volunteered to answer the questionnaire first was selected. The inclusion criteria were male and female adolescents, according to the World Health Organization , rangingA minimum representative sample size of 162 adolescents and 269 parents/guardians was calculated from the equation for a nonprobabilistic sample for an infinite population based on the proportion of 12% of 10–19 year olds and 50% of adult residents in the city of São Paulo in 2019 . A confiThe survey was composed of sociodemographic factors  and had 24 questions measuring: 1- knowledge about HPV and its clinical repercussions; 2- knowledge about the HPV vaccine; 3- barriers to the HPV vaccination; and 4- HPV vaccine acceptability . We chosThe answer options were “yes”, “no” and “I am not certain”. A score of (0) for incorrect answers and (1) for correct answers was attributed to each question. The proportions and confidence intervals for the correct answers were utilized to describe the correct answers for each question. For the score calculation, the numerator was the sum of correct answers multiplied by 100, and the denominator was the total number of answered questions. The questionnaire was tested on similar populations in a previous study . The insAdolescents and their parents/guardians were invited to voluntarily participate in the study and signed the written informed consent form and the consent form for adolescents under 16 years of age, when necessary.The self-administered questionnaires were answered individually in the waiting room with no repercussions for health care. Previously trained postgraduate and undergraduate students were present in the same room to collect answers to the questionnaire. After completion of the instrument, counseling and education about HPV were provided.The study population was divided into two groups: adolescents and their parents/guardians. The level of "suitable" knowledge about HPV, the vaccine and its clinical repercussions was the main endpoint of the study .Based on other studies ,19 in whThe following variables were considered explanatory variables: sex , age , marital status (single and stable relationship), childbirth (yes and no), education , family monthly income , and professional status (employed and unemployed). Stable relationship is defined as a relationship between two people who aim to start a family. We chose to use the variable “sex” in our study according to the vaccination program of the Ministry of Health, which considers biological sex for vaccination. An individual who does not fit this condition had the option of not responding”.The explanatory or independent variables were expressed as the means of absolute frequencies and proportions. Less than 2% of the information was ignored or left blank and thus considered missing.To analyze the association between the explanatory variables and "suitable" knowledge about HPV, clinical repercussions, and the vaccine and its acceptability, a Poisson regression model was performed by estimating the following measures: relative risk (RR) with a 95% confidence interval and the p value.The univariate analysis was performed between a group of “adolescents and parents/guardians" and the correct answers to questions that were part of the questionnaire to estimate the following measures: relative risk (RR) with 95% confidence interval (95% CI) and the p value.A multivariable adjusted model was constructed that included all variables that presented a p value <0.20 in the crude analysis. All analyses were performed using the STATA 15.1 program .This study was approved by the University of Sao Paulo, Medicine School Research Ethics Committee (1.938.072). Adolescents and their parents/guardians were invited to voluntarily participate in the study and signed the Written Informed Consent Form and the consent form for adolescents under 16 years of age, when necessary.A total of 1047 individuals participated in the study, of whom 74% (n = 776) were adolescents and 26% (n = 271) were parents/guardians. Both groups were composed of a majority of women, 69.5% (n = 530) among adolescents and 92.9% (n = 249) among parents/guardians. Among the adolescent participants, 64.9% (n = 504) were between 10 and 14 years of age, 98.6% (n = 714) were single, 4.5% (n = 33) had at least one child, 91.5% (n = 541) had less than a high school education and 36.2% (n = 258) had received at least one dose of HPV vaccine. Among the parents/guardians, 56.8% (n = 154) were between 40 and 59 years old, 65.4% (n = 149) were in a stable relationship, 73.1% (n = 190) had completed high school or higher, and 3% (n = 7) had received at least one dose of HPV vaccine .The main source of HPV information among adolescents was school , followed by TV/radio . Parents/guardians acquired information about HPV mainly through health professionals , followed by TV/radio  .Thus, questions answered correctly by less than 60% of the respondents were considered knowledge gap or barriers of acceptance, as shown in Tables The main knowledge gap in the parental group was that the question regarding whether the HPV vaccine would be part of girls' immunization records, with 59% (n = 157) correct answers. Among adolescents, only 24.4% (n = 179) had acceptable knowledge levels regarding the possibility that the HPV vaccine would decrease the chance of genital warts. Many adolescents expressed doubt that the HPV vaccine could be given to people who had previously had sexual intercourse, with a correct answer rate of 28.3% (n = 218) .Regarding the knowledge of HPV and its vaccine, the parents/guardians presented a higher level of knowledge for 15 of 17 questions on the subject. Parents/guardians were 2.48 times more likely than adolescents to know that HPV causes changes in the Pap smear test , 1.43 times more likely to know that HPV was a sexually transmitted infection  and 2.77 times informed that the HPV vaccine decreased the chance of having genital warts  .No significant difference  was found in the answers to the question regarding the number of inoculations required for complete vaccination and the question regarding whether the HPV vaccine was part of girls' immunization records  .Both groups reached the satisfactory level of more than 60% correct answers regarding the barriers and acceptability (Questions 18–23) issues for the HPV vaccine. Adolescents were 0.65 times  more likely to be vaccinated than their parents/guardians .Respondents with a stable marital status and a higher education level also presented significantly better results for knowledge and acceptability of HPV vaccine  in the univariate analyses.The multivariable analyses showed that girls in the adolescent group knew more about HPV than boys  and vaccinated adolescents had more correct answers than nonvaccinated adolescents . The category "high level of education" among parents/guardians corresponds to 3.38 times the number of correct answers to questions about HPV and its vaccine. [238% ] .This study evaluated related factors and divergences in knowledge about HPV, its vaccine and acceptability among Brazilian adolescents and parents/guardians. The parents who accompanied their children to a reference unit for adolescent health knew more about these aspects than the adolescents. Information reached the young people mainly through the media and school, while the parents/guardians were informed through health professionals and the media. The factor associated with suitable knowledge in adolescents was the being female and in parents/guardians, was a high education level.The adolescents presented low knowledge about HPV and its vaccine. The majority of our sample was composed of girls from 10 to 14 years old. Young people in this age group are the main target of the vaccination campaign for HPV in Brazil . This poThe most common source of information among adolescents was school, followed by conservative media (TV/radio). This finding may be justified, because the first vaccination campaign for HPV in Brazil took place in public and private schools. Initially, lectures were given on the subject, and then vaccines were applied to the students after obtaining the parents/guardians' consent .TV/radio media are an important source of information on the subject by reaching different age groups. This finding reinforces the promotion of qualified information bulletins to reduce myths and fake news about the HPV vaccine, which are mainly related to adverse events in the target population . In addiOur findings showed that parents/guardians knew more about HPV and its vaccine and that a high level of education is a factor related to this knowledge. In addition, parents/guardians are more likely to know that HPV virus causes abnormal Pap smear results, since half of the parents/guardians are women, who are enrolled in cervical cancer screening (Pap smear) . SimilarThe acquisition of knowledge depends on the experience ofthe subject as well as knowledge acquired during life. This occurs in the construction of both scientific knowledge and cultural knowledge . SeveralIn this study, we identified that the adolescents did not know that the HPV vaccine could be given to people who had already had sex. The efficacy of the HPV vaccine is broadened when it is received before an individual first engages in sexual intercourse, but individuals who have had a sexual life can still receive the vaccine , knowingThe only question the adolescents answered with greater accuracy than their parents/guardians was “Have you received the HPV vaccine yet?”. The reason for that might be the fact that adolescents over 16 years of age can be vaccinated without parental consent, especially those with HIV  [Young people older than the age covered by the Brazilian National Program of Immunization seek private services if they want to receive the vaccine. In addition, the National Health Surveillance Agency does not recommend applying vaccines to women out ofthe age range of 10 to 45 years and men from 9 to 26 years old .This study points out that women tended to have an acceptable knowledge of HPV and its vaccine. Women were also consistently more knowledgeable than men in similar study . The impThe responses showed no barriers regarding HPV vaccination and good acceptance and willingness to recommend the vaccine. Although both the adolescents and their parents/guardians presented a suitable level of acceptability, the parents/guardians were significantly more likely to have no barriers than the adolescents. Because the parents/guardians had more knowledge and higher levels of education, we expected them to have lower rates of barriers ,14. A stAlthough parents/guardians have a good level of knowledge, vaccination rates are still low in Brazil . ReportsHPV vaccination is a very effective public health policy for preventing cervical cancer. This policy is part of the National Immunization Program of the Brazilian Unified Health System ,40. HoweThe limitations of this cross-sectional study are that our sample was limited to adolescents and parents/guardians who were more likely to be interested in health issues, since they were recruited from a health center. Another limitation is that the outcome cannot be generalized to a different population, because it is a convenience sample. In addition, this limitation could be a source of bias in variable knowledge and perception, because this population analyzed individuals with access to health care, who did not represent the reality of other adolescents and parents/guardians in the Unified Health System. In this study, gender identity and sexual orientation were not considered, and we recognize that there is a gap in the research on these issues, which we will consider in future studies.The highlights of this study include elucidating the divergences of knowledge among adolescents and parents/guardians and indicating parents/guardians' inability to pass on their knowledge and experiences experiences to their children. It can support sexual and reproductive health education programs to develop specific health promotion actions.In fact, knowledge gaps and acceptance barriers are fundamental to the health education process and the social, cultural, and geographical contexts and aspects that integrate the individual and the community should be respected. According to the World Health Organization, prevention and primary health care depend on pillars in society, including the development of a country's education system . CounselFemale gender, for either adolescents or parents/guardians was related to suitable knowledge about HPV and its vaccine among Brazilian respondents to the questionnaire. While adolescents and parents/guardians had differences in knowledge about HPV and its vaccine, there was no disagreement regarding vaccine acceptance. High-quality education materials adapted for both gender should be developed to provide comprehensive and detailed information about HPV and its potential health consequences. Furthermore, we highlight the need for health actions that facilitate the exchange of knowledge and experiences between parents/guardians and children, with an emphasis given to male adolescents with a low education level.


This study was performed to discover the utility of HPV (Human Papillomavirus) testing in screening of cervical lesions and to provide the prevalence of HPV and the genotype distribution in a single center of Korea. (2) Methods: A total of 15,141 women who underwent both HPV testing and cervical cytology were enrolled in this retrospective medical record review study. (3) Results: HPV testing showed higher sensitivity than cytology for the detection of histological high-grade squamous lesions. Furthermore, the sensitivity and specificity of HPV testing varied depending on the method used. The BD Onclarity™ HPV assay had higher sensitivity (90%) than the MyHPV CHIP™ kit  for high-grade squamous lesions. A combination of MyHPV CHIP™ and cytology detected 90.9% (30/33) of histological high-grade squamous lesions. A combination of BD Onclarity™ HPV assay and cytology detected 96.55% (84/87) of histological high-grade squamous lesions. In addition, HPV prevalence and genotype distribution were different depending on the HPV testing method used. (4) Conclusion: HPV testing showed higher sensitivity than cytology, but the sensitivity and specificity of HPV testing had variation depending on the method used. Cervical cancer is one of the most common cancers in Korean women, and in 2019, 2856 new cases were detected and 834 deaths occurred ,8,9,10. n = 11,142, aged 23–86; 42 years (median) and 41.5 years (mean)) and the gynecology department  and 47.5 years (mean)) of Samsung Changwon Hospital. The exclusion criteria included having undergone previous surgical procedures of the cervix, including conization, trachelectomy, or hysterectomy. To determine HPV status, the MyHPV CHIP™ kit  and the BD Onclarity™ HPV assay on the BD Viper™ LT system  were used  and 43.5 years (mean)), and the BD Onclarity™ HPV assay was performed from March 2016 to June 2017  and 43.3 years (mean)). Of these 15,141 women, 295 (1.95%) underwent cervical resection, including conization, trachelectomy, or hysterectomy, until August 2019. This study was approved by the Institutional Review Board (IRB) of Samsung Changwon Hospital, Changwon, Korea (IRB FILE No. 2020-01-002). This study was a retrospective medical record review study and the IRB waived the need for written informed consent. The medical records of Samsung Changwon Hospital between February 2015 and June 2017 were gathered. A total of 15,141 women  and 43.36 years (mean)) who underwent both HPV testing and cervical cytology were enrolled in this study from the health checkup center  had been performed.The histological diagnoses were obtained from pathologic reports using electronic medical records retrospectively. All diagnoses had been performed in the department of pathology, Samsung Changwon Hospital. In the 15,141 women, only 195 women had undergone cervical resection in the department of gynecology, Samsung Changwon Hospital. Formalin-fixed paraffin-embedded (FFPE) blocks had been made using the cervical tissues. All tissues had been sectioned with 5-μm-thick microtome and stained by H&E (hematoxylin and eosin) stain. The stained slides had been diagnosed using an optical microscope by three pathologists. The MyHPV CHIP™ kit is a PCR (Polymerase chain reaction)-based DNA microarray system. It was approved by the Ministry of Food and Drug Safety of the Republic of Korea  in July 2004. All assays were performed according to the manufacturer’s protocol. Cervical cells for HPV testing were obtained using the soft brushes separately from Pap smears. The brushed tissues were supplied to the MyHPV CHIP™ kits and DNA was isolated. Target HPV DNA was amplified by PCR using specific primers with β-globin DNA . According to the protocol provided by the MyGene Co, Seoul, Korea, DNA isolation and PCR were performed. The PCR products were denatured by heating for 5 min at 95 °C, and then they were mixed with hybridization solution and applied to the DNA chips. The hybridizations were performed at 43 °C for 90 min, and then the products were washed with saline–sodium phosphate–EDTA and air-dried at room temperature. Hybridized HPV DNA signals were detected using a DNA chip scanner . Positive signals revealed a band of 150 base pairs on the gel electrophoresis of the HPV-PCR. The absence of these 150 base pairs on the gel electrophoresis was considered “HPV-negative”. This system detected 11 types of high-risk HPV , 8 types of low-risk HPV , and other types of HPV (unspecified HPV).The cervical brush diluents in cases of conventional smear and the aliquots of the SurePath sample were used for BD Onclarity HPV testing. The cervical brush diluents did not require pre-handling before HPV testing, but each SurePath sample was vortexed briefly and a 0.5 mL aliquot was supplied to 1.7 mL of a BD HPV LBC diluent. Then, the samples  were pre-warmed for 30 min at 120 °C on the BD pre-warming heater with positive and negative controls. The pre-warmed specimens were loaded onto the BD Viper LT System after cooling. Then, all of the steps, including extraction and amplification of target DNA, were performed automatically by the BD Viper LT System. Next, the specimens with fluorescent detector probes were transferred to a three-wall, four-channel real-time PCR system for genotyping with the internal controls in each wall. The signals were detected by the integrated VIPER LT reader. The system was used for high-risk types 16, 18, 31, 45, 51, and 52 and other high-risk genotypes by group .All analyses were performed using R version 3.6.2., the R Foundation for Statistical Computing, . The difference of HPV high-risk prevalence between MyHPV CHIP™ and the BD Onclarity™ HPV assay was calculated by Fisher’s exact test. The difference between the prevalence of high-risk HPV and the prevalence of cytological squamous lesions was calculated by using the Exact McNemar’s test in the package “exact2×2”. The correlation between high-risk HPV infection and cytological diagnosis was calculated using Spearman’s correlation. To compare the proportion of histological high-grade squamous lesions in the negative cytology/positive HPV group with the positive cytology/negative HPV group, Fisher’s exact test was performed. The odds ratio of HPV infection in the normal cytology group and the positive cytology group was calculated by Fisher’s exact test. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (PLR), and negative likelihood ratio (NLR) were calculated by using “epi.tests” in the package “epiR”. The differences of sensitivity and specificity in MyHPV CHIP™, the BD Onclarity™ HPV assay, and cervical cytology were calculated by using Exact McNemar’s test in the package “exact2×2”. The ROC (receiver operating characteristic) curves drawn by using ROC in the package ”Epi”.From February 2015 to February 2016, the MyHPV CHIP™ method was conducted for HPV detection. HPV genotypes in the MyHPV CHIP™ group are shown in From March 2016 to June 2017, the BD Onclarity™ HPV assay was conducted for HPV detection. HPV genotypes in the BD Onclarity™ HPV assay group are shown in p = 1.496 × 10−11). The prevalence of HPV is shown in p = 8.376 × 10−16; HPV52: 17.26% vs. 5.05%, p < 2.2 × 10−16). In the MyHPV CHIP™ group, 427/5324 (8.02%) had high-risk HPV and 4587/5324 (86.16%) showed negative for HPV. However, in the BD Onclarity™ HPV assay group, 1124/9817 (11.45%) had high-risk HPV and 8693/9817 (88.55%) showed negative for HPV. High-risk HPV was found in significantly higher prevalence in the BD Onclarity™ HPV assay than MyHPV CHIP™ .The age-related prevalence of high-risk HPV infection is shown in p = 1.099 × 10−6)  had high-risk HPV infection, 310 (5.82%) had low-risk or another type of HPV infection, and 4587 (86.16%) showed negative for HPV infection. In the 5315 satisfactory cytology cases, 318 (5.98%) had squamous lesion  or worse); 125 cases of the 427 high-risk HPV infection group (29.27%), 56 cases of the 310 low-risk and other types of HPV infection group (18.06%), and 137 cases of the 4578 negative HPV infection group (2.99%) had cytological squamous lesions (ASCUS or worse). There was a difference between the prevalence of high-risk HPV  and the prevalence of cytological squamous lesions , and the difference was statistically significant ( × 10−6) .p < 2.2 × 10−6)  had high-risk HPV infection and 8693 (88.55%) showed negative for HPV infection. In the 9806 satisfactory cytology cases, 576 (5.87%) had squamous lesion (ASCUS or worse); 310 cases of the 1124 high-risk HPV infection group (27.58%) and 266 cases of the 8693 negative HPV infection group (3.06%) had cytological squamous lesions (ASCUS or worse). There was a difference between the prevalence of high-risk HPV  and the prevalence of cytological squamous lesions , and the difference was statistically significant ( × 10−6) .p < 2.2 × 10−16). Additionally, the BD Onclarity™ HPV assay result and the cytology (squamous lesion) showed a significant correlation . The MyHPV CHIP™ HPV (high-risk) result and the cytology (squamous lesions) showed a significant correlation . Additionally, 67.74% of those with positive cytology (ASCUS or worse)/positive high-risk HPV had high-grade squamous lesions in their histologic diagnosis; 5.36% of those with negative cytology (threshold: LSIL or worse)/negative HPV infection had histological high-grade squamous lesions; 27.78% of those with negative cytology (LSIL or worse)/positive high-risk HPV infection and 21.43% of those with positive cytology (LSIL or worse)/negative HPV infection had high-grade squamous lesions; and 76.92% of those with positive cytology (LSIL or worse)/positive high-risk HPV infection had high-grade cervical lesions in their histologic diagnosis. From the total 33 histological high-grade squamous lesion cases, three showed negative cytology and negative HPV with the MyHPV CHIP™ method. This means that the combination of MyHPV CHIP™ and cytology detected 90.9% (30/33) of histological high-grade squamous lesions /negative HPV infection had histological high-grade squamous lesions (CIN2 or worse). Furthermore, 30.77% of those with negative cytology (threshold: ASCUS or worse)/positive high-risk HPV infection had high-grade squamous lesions, and 13.04% of those with positive cytology (ASCUS or worse)/negative HPV infection also had high-grade squamous lesions. There was a difference between those with negative cytology/positive high-risk HPV  and those with positive cytology/negative HPV  in the prevalence of high-grade cervical lesions, but it was not statistically significant ( lesions .p = 0.209). Furthermore, 80.25% of those with positive cytology (ASCUS or worse)/positive high-risk HPV infection had high-grade squamous lesions in their histologic diagnosis; 5.45% of those with negative cytology (threshold: LSIL or worse)/negative HPV infection had histological high-grade squamous lesions; 65.79% of those with negative cytology (LSIL or worse)/positive high-risk HPV infection and 46.15% of those with positive cytology (LSIL or worse)/negative HPV infection had high-grade squamous lesions; and 80.3% of those with positive cytology (LSIL or worse)/positive high-risk HPV infection had high-grade squamous lesions in their histologic diagnosis. From the total 87 histological high-grade squamous lesion cases, 3 showed negative cytology and negative HPV with the BD Onclarity™ HPV assay. This means that the combination of BD Onclarity™ HPV assay and cytology detected 96.55% (84/87) of histological high-grade squamous lesions /negative HPV infection had high-grade squamous lesions (CIN2 or worse) in their histologic diagnosis; and 56.52% of those with negative cytology (ASCUS or worse)/positive high-risk HPV infection and 33.33% of those with positive cytology (ASCUS or worse)/negative HPV infection had high-grade squamous lesions. There was a difference between negative cytology/positive HPV  and positive cytology/negative HPV  in prevalence of high-grade squamous lesions, but it was not statistically significant ( lesions .p = 0.0425) and the odds ratio of high-risk HPV was 6.38  for histological high-grade squamous lesions. In the positive cytology group (ASCUS or worse) of MyHPV CHIP™, the odds ratio of HPV infection was 9.23  and the odds ratio of high-risk HPV was 10.42  for histological high-grade squamous lesions. In the normal cytology group of the BD Onclarity™ HPV assay, the odds ratio of HPV high-risk infection was 19.19  for histological high-grade squamous lesions. In the positive cytology group (ASCUS or worse) of the BD Onclarity™ HPV assay, the odds ratio of HPV high-risk infection was 7.9  for histological high-grade squamous lesions.In the normal cytology group of MyHPV CHIP™, the odds ratio of HPV infection was 5.64 . For high-grade squamous lesion detection, the BD Onclarity™ HPV assay or cytology (ASCUS or worse/ LSIL or worse) showed the best sensitivity  and the lowest negative likelihood ratio . MyHPV CHIP™ high-risk infection had higher specificity  than the BD Onclarity™ HPV assay  or cytology  for high-grade squamous lesion detection. Especially, MyHPV CHIP™ high-risk infection showed significantly higher specificity than cytology (ASCUS or worse) for high-grade squamous lesion detection (p = 0.00599). MyHPV CHIP™ high-risk infection and cytology (LSIL or worse) showed the best specificity  and the highest positive likelihood ratio  for high-grade squamous lesion detection. The BD Onclarity™ HPV assay and cytology (ASCUS or worse/LSIL or worse) showed the highest positive predictive value  compared to the others. MyHPV CHIP™ or cytology (LSIL or worse), MyHPV CHIP™ high-risk or cytology (LSIL or worse), and the BD Onclarity™ assay or cytology (LSIL or worse) showed the highest negative predictive values . The addition of MyHPV CHIP™ to cytology increased sensitivity compared to cytology alone , but it was not statistically significant . The addition of BD Onclarity™ HPV assay to cytology increased sensitivity compared to cytology alone , and it was statistically significant . The addition of MyHPV CHIP™ to cytology increased specificity compared to cytology alone , and it was statistically significant . The addition of BD Onclarity™ HPV assay to cytology increased specificity compared to cytology alone , and it was statistically significant . The addition of cytology to MyHPV CHIP™ increased sensitivity compared to MyHPV CHIP™ alone (MyHPV CHIP™ high-risk/ASCUS+ 91% vs. MyHPV CHIP™ high-risk 76%), but it was not statistically significant (p = 0.0625). The addition of cytology to BD Onclarity™ HPV assay increased sensitivity compared to BD Onclarity™ HPV assay alone (BD Onclarity™/ASCUS+ 97% vs. BD Onclarity™ 90%), and it was statistically significant (p = 0.000488). The addition of cytology to MyHPV CHIP™ increased specificity compared to MyHPV CHIP™ alone (MyHPV CHIP™ high-risk/ASCUS+ 89% vs. MyHPV CHIP™ high-risk 79%), and it was statistically significant (p = 0.0039). The addition of cytology to BD Onclarity™ HPV assay increased specificity compared to BD Onclarity™ HPV assay alone (BD Onclarity™/ASCUS+ 81% vs. BD Onclarity™ 69%), and it was statistically significant (p = 0.00195). The addition of HPV testing to cytology increased sensitivity and specificity compared to cytology alone. Also, the addition of cytology to HPV testing increased sensitivity and specificity compared to HPV testing alone. According to these results, HPV testing and cytology were complementary. The ROC curves are shown The performance of test combinations for the detection of high-grade squamous lesions (CIN2 or worse) is shown in The performance of the test combinations for the detection of high-grade squamous lesions in those under the age of 45 and the those aged 45 or above is shown in Traditionally, cervical cancer screening is performed using cytology. Cytology-based screening has reduced the incidence and mortality of cervical cancer in many countries ; howeverp = 8.376 × 10−16; 52: 17.26% vs. 5.05%, p < 2.2 × 10−16). According to our results, it is possible that HPV prevalence appears differently depending on the method and the timing of the investigation. Furthermore, high-risk HPV showed a significantly higher prevalence in the BD Onclarity™ HPV assay group than in the MyHPV CHIP™ group . According to a previous meta-analysis, age-related HPV prevalence in countries shows a bimodal curve with a first peak at younger ages, a plateau at middle ages, and a rebound at older ages [p < 1.044 × 10−8).According to the recent literature, HPV52 and HPV58 present higher prevalence in Asian women than in Western women ,19,20. Ider ages . In our The current studies indicate that HPV testing showed higher sensitivity than cytology, but the sensitivity and specificity of HPV testing varied depending on the HPV testing method used ,23,24. OThe addition of HPV testing to cytology increased sensitivity and specificity compared to cytology alone. Additionally, the addition of cytology to HPV testing increased sensitivity and specificity compared to HPV testing alone. Thus, HPV testing and cytology were complementary. The obvious limitation in this study was a small sample size of confirmed histological diagnoses. Only about 14.5% of women of abnormal cytology or high-risk HPV infection underwent cervical resection in our hospital . The majority of cases (73.59%) were women identified through systemic health screening. Many of them underwent cervical resection in other gynecological hospitals and we could not access their histologically confirmed diagnoses. Besides this, we failed to exclude pregnant women and vaccinated women due to their incomplete medical information.HPV testing showed higher sensitivity than cytology, and the sensitivity and specificity of HPV testing varied depending on the HPV testing method. HPV prevalence and genotype distribution were also different depending on the method. The BD Onclarity™ HPV assay had higher sensitivity than the MyHPV CHIP™ kit for high-grade squamous lesions. Furthermore, the combination of cytology and HPV testing increased sensitivity and specificity compared to one method alone; thus, cytology and HPV testing are complementary.


While the potential use of energy harvesters as structural health monitors show promise, numerical models related to the design, deployment and performance of such monitors often present significant challenges. One such challenge lies in the problem of leak detection in fluid-carrying pipes. Recent advances in experimental studies on energy harvesters for such monitoring has been promising but there is a paucity in existing literature in linking relevant fluid–structure interaction models around such applications. This paper addresses the abovementioned issue by developing a numerical model with Computational Fluid Dynamics (CFD) and Finite Element (FE) tools and carries out extensive analyses to compare it with existing experiments under controlled laboratory conditions. Conventional Polyvinylidene Fluoride (PVDF) films for leak detection and monitoring of water pipes were considered in this regard. The work provides guidelines on parameter selection and modeling for experimental design and repeatability of results for these types of experiments in future, around the demands of leak monitoring. The usefulness of such models is also demonstrated through the ability to estimate the optimum distribution frequency of these sensors that will enable the detection of the smallest leak of consequence under a known or established flow condition. Vibration leak detection methods have been identified as effective for early leak detection in pipes. They are a popular choice for any leak detection set-up because they are non-invasive and more suited for monitoring than inspection ,2,3. TheObtaining the pipe surface vibration levels numerically for the healthy pipe state and a number of leak states are essential for experimental design and numerical validation of the PVDF patches for water pipe leak detection, and this task is a two-pronged complex problem. The first phase of the problem deals with the turbulent flow dynamics, Fluid–Structure Interaction (FSI), and leak induced Negative Pressure Wave  with the output from this step being the internal pipe wall pressure fluctuations. The second addresses the propagation of resulting internal pipe wall pressure fluctuation to the external pipe surface exciting vibration response with the output being either pipe external surface strain or acceleration . After obtaining the pipe surface strain level for the all the simulation cases, and knowing the properties of the PVDF patches, the theoretical voltage output from the PVDF patches can be calculated for positions of interest along the pipe length, using the already established strain–voltage relationship for PVDF films .In addition to the numerical validation of these piezoelectric patch sensors, this paper also presents a numerical methodology for determining the optimum frequency distribution of these sensors  that will enable the detection of the smallest conceivable leak of consequence under any known/established flow condition. To be able to detect a small pipe leak under low flow rate conditions using vibration patch sensors, the distance between two sensors must be equal to or less than the length of the portion of the pipe that will be influenced by the induced NPW due to the onset of the leak at that flow condition. Hence, the lowest flow rate, the smallest expected leak size, and the length of pipe influenced by the leak-induced NPW before its complete decay are crucial information for determining the distribution frequency of sensors adopted for a pipe leak vibration monitoring application. Such guidance cannot be obtained from the experimental validation exercise presented in  because The results and findings from this paper guide the procedure of creating a numerical framework for interpretation of existing or earlier experiments within the context of the Fluid–Structure Interaction for pipeline leaks in various sectors of application. The work also helps in designing future experiments and provides some quantitative estimates on the choice of parameters for modeling, measuring and comparing along with their quantitative. Finally, the work can be used to obtain the minimum number of sensors required to detect a certain level of leakage, for a given flow-rate. The findings can be easily adapted to a range of sensors and can thus be useful for development of novel sensors and measurement chains around this topic.Fluid flow regimes are mainly laminar or turbulent . LaminarThe ratio of inertial forces to viscous forces within a flowing fluid, can tell if the flow is laminar or turbulent. This ratio is given by a dimensionless quantity called the Reynolds number (Re) , and theLaminar flows can be described completely mathematically by the continuity, Navier–Stokes, energy conservation equations and the equation of state. However, in the case of turbulent flows, in addition to the aforementioned equations, the turbulence transport properties must also be accounted for . CommercIn practice, there are three main methods for the analysis of turbulent flows in commercial CFD codes, namely: Direct Numerical Simulation (DNS), Large Eddy Simulation (LES) and Reynolds-Averaged Navier-Stokes (RANS) models. With DNS being the most accurate and RANS the least accurate.Direct numerical simulation (DNS) solves these equations numerically in a rigorous way to a desired accuracy without any additional model or correlation. However, its application is still limited because existent problems require a large amount of computational resources, exceeding the capacity of conventional computers, hence it is not a very practical model. For this reason, DNS was not employed in solving the FSI problem of this research ,18.k–ε model and the k–ω model are the commonly used RANS-based two equations turbulence models. The two extra transport equations accounts for the turbulent properties of the flow. Depending on the chosen model, the transported variables are most often the turbulent kinetic energy k–ω model has an advantage of having an improved performance for near wall boundary layer regions of the flow under adverse pressure gradients when compared to the k–ε model. The k–ε model on the other hand, is more robust in the free shear flows and mainstream regions [k–ω (SST k–ω) model [k–ω turbulence model operates by employing the k–ω model in the near-wall region and by employing a blending function, switches to the k–ε model in the free shear flow turbulent region [Reynolds Averaged Navier–Stokes (RANS) employs equations in modeling the turbulent flow. These models do not provide instantaneous values for the flow and are based on time averages, e.g., they do not compute the pressure fluctuations at the Fluid-Structure Interface ,23. The quations . The k–ω regions . An inteω) model . The SSTt region .k–ω RANS model was employed in the process of selection of a mesh for the pipe models before simulation, as one of the selection criteria requires time-averaged solutions.In this study, internal pipe wall pressure fluctuations or variations is the output quantity of interest from the CFD simulations and it is required as input for the second phase of FE simulations to obtain the pipe surface vibrations, hence, RANS based models cannot accomplish the central purpose of this study. However, the SST As described above, the reasons that DNS and the RANS models cannot be employed for obtaining the internal pipe wall pressure fluctuations from the turbulent fluid flow simulation are clear. Here, the LES model, which models the actual physics of the flow better when compared to the RANS models was employed. The LES approach is a hybrid model derived from a combination of DNS and the RANS models. In contrast to a time-averaged approach, LES provides a model that computes the instantaneous velocity and pressure field, in contrast to the time-averaged approach adopted by RANS and it is not as computationally expensive as DNS . In LES,k–ω RANS model employed in the mesh selection process can be found in [In this study, the commercial codes employed were ANSYS FLUENT for the CFD (first phase) simulations and ANSYS Transient Structural for the (FE second phase) simulations. The governing equations and basic formulations of the LES model, which is the primary turbulence model employed in this study can be found in ,30. Thatfound in ,26.To get accurate results from the Fluent turbulent simulation, the pipe flow model and simulation set up must at least come close to satisfying certain conditions. There are some parameters that can guide the preparation and validation of the model before it is employed for simulation runs.One of such parameters is the length of the streamwise pipe domain. For a good FLUENT solution, it is advised that the flow should be fully developed. For this to occur, the length of pipe should be at least 5 times the internal or hydraulic pipe diameter . Other ihe wall) .(2)y+=uTo deal with near wall turbulence, the way the near wall flow is treated is important, and this is done using wall functions.The dimensionless velocity The laminar sublayer is characterized by small values of For larger The local There are two common choices for the wall function: standard wall function and the enhanced wall function. In the standard wall function, the first grid is located within the range ual to 1 .To resolve the high energy containing eddies using the LES turbulent model, the mesh of the fluid flow model must be sufficiently fine. Therefore, the meshing of the turbulent flow problem in LES is crucial as it has significant influence on the results. The size of the largest eddies is described by the turbulent length scale, c energy . Hence, In selecting transient simulation conditions like the time-step, it is important to consider the characteristic time of transit of a fluid element across a volume. To thoroughly resolve a turbulent flow, the ratio of the time step to the time of transit of the fluid element known as the courant number should be less than 1. The courant number, which provides insights of the fluid movement through the computational cells, is a dimensionless quantity, and can be calculated from:A courant number This section first presents an overview of the scope of simulations in the numerical model, identifying the range of flow rates, defining the healthy benchmark and outlining the types of analyses that are carried out subsequently. The validation of the selected mesh is presented next and the wall function of the models is established. Matching of pressure drop through modeling is carried out next, before the final choice of mesh. Considerations of turbulence and mass flow rates due to the leak are considered next. Finally, the vibrations from fluid flow are estimated from the Fluid-Structure Interaction model and subsequently converted to pipe strains, and linked to energy harvesting.For the numerical validation of the PVDF patches, the pipe model and simulation conditions were designed to replicate the experimental conditions detailed in . Hence, Three healthy pipe models with different mesh models were prepared and an analysis was carried out to validate these meshes and determine the best one to be adopted for the simulation runs. Simulation runs were then performed on the chosen pipe flow model using the LES WALE model of ANSYS FLUENT for the healthy state and leak pipe states of the pipe at various flow conditions. On obtaining the solution of the flow field, the pressure field on the pipe wall was exported to a Finite Element (FE) package  to calculate the pipe response in the form of the pipe surface strain. This pipe surface strain at the positions along the pipe length where the PVDF patch sensors were bonded in the experimental campaign is then used to calculate the theoretical voltage output of the PVDF patch sensors.Three different pipe mesh models were prepared for the healthy pipe state and a model selection exercise was performed to determine the model, if any, that is best suited for the exercise. The validation exercise was carried out for the healthy pipe state only, at all 5 test flow rates, therefore, it involved 5 simulation scenarios out of the 25 total scenarios. In addition to the important modeling parameters mentioned in the previous section, a comparison of the static pressure gradients . The table below shows a summary of the theoretical and Fluent pressure gradients for all simulation cases and candidate models.friction ,37. TablFrom the result of the mesh validation exercise, it is clear that mesh 3 (the finest mesh) satisfied both selection criteria best and will afford the best opportunity of obtaining accurate results from the simulations. The performance of mesh 2 was fair, but it did not satisfy the enhanced wall treatment condition and the difference in the number of cells and nodes when compared to mesh 3 was not large enough to present a substantial gain in computation time. Hence, mesh 3 was selected for this exercise. A close look at After selection of the mesh model, the first phase for the validation of the PVDF sensors was executed using the LES WALE turbulence model. As earlier stated, the LES turbulent model is the best practical model for solving transient turbulence problems. This phase involved running simulations for the healthy state pipe and damaged state pipes for all 5 flow rates to obtain the internal wall pressure fluctuations due to FSI for the healthy state pipe and FSI and NPW for the leak state pipe. The idea here is that the influence of the leak will cause an increase in the pipe pressure fluctuation due to the leak induced NPW, and this increase in NPW will in turn reflect as an increase in the pipe surface strain for the leak state pipe when compared to the healthy state pipe at the same flow rate.For the simulations, the healthy pipe model was that of the selected mesh model and the BCs also remained the same as those employed in the mesh selection exercise. For the leak states of the pipe, leak being represented as 2 mm, 5 mm, 7 mm and 10 mm diameter circular holes were introduced at the 60 cm mark along the pipe length of the selected model without really changing the other model mesh properties, the only modification from the healthy state pipe model is that the mesh nodes closer to the leak was made finer. The leaks have a small leak wall of 2.5 mm, which is the same as the thickness of the test pipe, this is because they were modeled such that they represent the physical pipe leak state as best as possible. Consequently, in addition to the inlet, outlet and pipe wall boundaries, there were two additional boundaries, namely the leak wall, and the leak outlet. The BC for the leak wall was the same as the pipe wall, i.e., stationary wall with no slip, and mass flow outlet BC was employed for the leak outlet. Since the leak discharges to the atmosphere, atmospheric condition was selected as the operating condition at the leak outlet. The velocity-inlet and pressure outflow BCs remained the pipe inlet and pipe outlet BCs.A is the area of the pipe inner cross-section, The theoretical leak mass flow rates 3) below .(13)Ql=The relationship for calculating found in , and was [CK=0.6 . Table 4For the LES simulations, a time-step size of 0.001 s was selected, and the simulation was run for 2000 time-steps for each simulation case. This amounted to a total flow time of 2 s. The courant number criterion was used to determine if the selected time-step size and mesh model was adequate for this transient simulation exercise. As mentioned earlier, for a good solution the Courant number is less than one. Using the above transient conditions, the healthy pipe simulations were first conducted for all 5 flow rates to determine the courant number.Similar to the wall Additionally, another noteworthy point is that the range of values (maximum and minimum) obtained from the courant number contours for the simulation at the highest flow rate was higher than that recorded for the lowest flow rate, confirming that courant number was directly proportional to the average flow velocity. This justifies the decision to use the highest flow rate courant number contour for validating the time-step and pipe mesh model.After the successful validation of the transient simulation conditions, the simulations were conducted for all the pipe states  at all 5 flow rates using a time-step size of 0.001 s, and 2000 time-steps. This amounted to a total of 25 simulation cases. The average time to complete one simulation ranged from 26 to 30 h. During the simulation, the data sampling for time statistics was turned on, and set to every time step, meaning that all 2000 time-steps were employed in calculating the transient results from the FLUENT simulation, After the simulations have been completed, the fluctuating pressure of the internal pipe wall was then extracted and exported into a transient finite element model of the pipe to obtain the external pipe surface strain conditions for each pipe state and flow condition.Although all 2000 time-steps were employed in calculating the FLUENT transient results, the pressure fluctuations of the internal pipe wall were extracted for every 10 time-steps for each simulation case and imported into the pipe FE model in ANSYS Transient Structural to determine the structural response (pipe surface strain fluctuation) of the pipe using ANSYS CFD-Post. This meant that a total of 200 time-step pressure fluctuation results were imported into ANSYS Transient Structural per simulation case. This is because extracting these results is very laborious and time consuming as it must be done one time-step at a time for each case. There is also the problem of file size restrictions when saving extracted data. The extraction of the file was done with the aid of the record session option in ANSYS CFD-post.Before importing the pressure fluctuations, the FE pipe model was set up and validated. For the model set up, after meshing, the pipe support type was specified to be fixed supports as both inlet and outlet boundary conditions. The distance between these supports being the length of the test pipe, i.e., 1 m. This best represents the physical condition of the test pipe during the experimental validation exercise (as it was clamped to the test rig at both inlet and outlet) . The pipijd is the piezoelectric constant, Y = Young’s modulus of the Piezoelectric material and After validating the FE model, it was adopted for the transient structural simulations. As earlier stated, the pressure fluctuations were imported into the transient structural model for all 25 simulation cases from FLUENT. The pipe surface strain response was recorded and the theoretical performance of the PVDF sensor was evaluated for positions of interest along the pipe length, employing the PVDF film sensor–voltage relationship established by  and showEnsuring that there is optimum distribution of vibration sensors along the pipe length for any pipe leak vibration monitoring application is very important. If the distance between the sensors is much less than what is optimal to detect the smallest expected leak size, although leak detection might be achieved, it will lead to deploying more sensors than what is required thereby driving costs up. This will have a significant financial impact in extensive applications involving many sensors. On the other hand, the distance between the sensors being more than what is optimal will affect the performance of the monitoring system negatively, as small leaks might not be detected. This paper attempts to establish a simple method for determining this optimum sensor distribution. Here, we relied on CFD modeling using ANSYS FLUENT to achieve this by modeling the smallest leak in the pipe model adopted for the numerical validation of the PVDF patches and running simulations for the lowest operating flow rate. Since leak detection is reliant on transient leak induced NPW altering the pipe surface strain conditions, the length of the area of pipe affected by this NPW obtained from simulations based on the above leak size and flow rate conditions, can be adopted as the maximum allowable distance between two sensors.To demonstrate this idea, we took the pipe model and simulation conditions employed in the preceding subsection of this paper for validating PVDF patch sensors for leak detection into consideration. The lowest flow rate in this case was 26.50 L/min and the smallest leak size 2 mm. The pipe model being a 1 m long galvanized steel pipe. From the results obtained, it was clear that that the influence of the small leak at that flow rate was prominent throughout the entire pipe length, because although the leak-induced NPW started decaying away from the leak, it still had positive values both at the pipe inlet and pipe outlet (more details on this is provided in the next section), this shows that the pipe length was too short to determine the maximum distance between two sensors to detect the smallest leak size of 2 mm at the lowest pipe flow rate.Here, the solution to this problem was attempted by creating a healthy pipe mesh model with the same internal diameter but a longer length. The mesh of this model was validated following the steps employed in the Similarly, the 2 mm leak pipe model was also created, and it had the same properties as the healthy pipe model, except for the additional leak outlet and leak wall BCs. This time, the leak was introduced at the half-way along the pipe length, i.e., 2 m from the inlet and outlet. The BCs employed here was also the same as that employed in the preceding This section demonstrated the impact of the model developed in this paper. The simulations first established the root-mean-square estimates of negative pressure waves in pipes to be a valid indicator of the leak. The effect of presence, location and the extent of leakage and its interaction with the distance from the sensor were investigated next extensively for various flow rates and levels of leakage. The effective calibrations of markers of such detection are presented, which is particularly relevant for any future experimental design. The section subsequently demonstrated how the spacing of the sensors could be determined through the developed numerical method as a function of the smallest size of leak that is intended to be detection.Post Fluent simulation, the pipe wall fluctuating pressure for the simulation time, at any point along the pipe length of the pipe, could be obtained. The frequency of sampling being the inverse of the time-step size, hence 1000 Hz. The instantaneous pipe wall fluctuating pressure  of the static pressure. The RMSE of static pressure is the same as the root mean square of the fluctuating pressure ngth see , for allNPW have positive values for all simulation cases. This is the case for the smallest leak size 2 mm at the lowest flow rate that unsurprisingly records the least NPW with decreasing flow rates, i.e., the curves for 90.85 L/min had the highest magnitudes and 26.50 L/min the least magnitudes. This is because as the flow rate increased, the flow turbulence increased and consequently the FSI. Additionally, flow also had a directly proportional relationship with the leak induced NPW.NPW could prove an effective method for leak detection and monitoring.The findings from this analysis served to confirm that an Post transient structural simulations, the pipe vibration response in terms of surface strain had to be obtained at specific positions along the pipeline to be able to calculate the theoretical voltage output from PVDF patch sensors. The positions selected were 20 cm, 60 cm and 80 cm from the pipe inlet, named sensor position 1 (SP1), sensor position 2 (SP2) and sensor position 3 (SP3) for the purpose of analysis see . Sensor These are the same positions where the patches were bonded for the experimental campaign detailed in . The pipThe above figure shows that at a given flow rate, the amplitude of the recorded strain increased with the introduction of a 2 mm small leak and this amplitude increased even further with increasing leak severity.To determine the theoretical performance of the PVDF patch sensors, the theoretical root mean square voltage, The horizontal (x) axis from It is important to note that, the Vrms values of the pipe states simulated for are represented on the plots by markers (see figure legend). The Vrms values of the intermediate pipe states inferred by joining the markers to form curves do not represent data from this exercise as simulations were not conducted at these intermediate states. Joining the markers to form curves is for visual aid, to help appreciate the trend of the theoretical sensors’ output with the worsening pipe leak state.From The trend of the curves obtained from the results of this numerical validation exercise explained above mirrors that obtained from the experimental validation exercise detailed in , and boty bonded , any impAdditionally, since the leak induced NPW that aids leak detection was highest at the leak position and decayed away from the leak in both directions, the area of the pipe closest to the leak could be identified, by monitoring the leak induced vibration at various sections of the pipe. The fact that the sensors were at different distances from the leak position was utilized in evaluating the theoretical performance of the PVDF sensors for leak localization. The approach employed here is same as that employed in the experimental validation , where tThe leak index was calculated for all simulation cases and the three PVDF patch sensors. The horizontal (x)-axis representation is same as that employed for The results numerically validate the experimental results from the PVDF patch sensors obtained in , as the As mentioned earlier, the healthy pipe and 2 mm leak pipe states at a flow rate of 26.50 L/min simulation conditions from the numerical validation exercise were adopted for this study. The 2 mm leak pipe state at flow rate of 26.50 L/min simulation condition corresponds to the smallest leak pipe state at the lowest flow rate from the numerical exercise. For this study, the length of the pipe model was 4 m as opposed to the 1 m length from the numerical validation study. After FLUENT simulations, the From Therefore, for the pipe model in this exercise and our simulation condition, the maximum distance between two sensors for the smallest leak size to be detected at the least operating pressure was approximately 3.60 m.The presented numerical framework and related experiments could thus adapt itself to not just detection hardware  but alsoThis paper presented a numerical model, combining the Fluid–Structure Interaction to estimate the vibrations and dynamic strains on a fluid-carrying pipe and estimated the impact of leaks. The work then linked this model to energy harvesting based monitoring of such leaks through a PVDF patch, in the context of existing experimental results. This method relies on monitoring the leak induced NPW and its attenuation away from the leak. The results from the numerical validation exercise corroborated the experimental results presented in , providiDespite these advantages, the study naturally has some limitations. The energy-harvesting model is relatively simplistic and variations of harvesting circuits have not been explored, limiting the discussions to the open circuit voltages. The electromechanical coupling is kept constant, but in low powers, this coefficient may vary. The challenge of potential false alarms caused by environmental perturbations unrelated to the leak has not been investigated here either. Additionally, effects of temperature, chemical exposure, humidity and material degradation and durability have not been considered in this model.


Emerging observational evidence suggests a single-dose of human papillomavirus (HPV) vaccine may be protective against vaccine-targeted HPV infection and associated cervical dysplasia. We aimed to demonstrate whether a single dose of quadrivalent HPV (4vHPV) vaccine was immunogenic and reduced HPV detection rates in young women in Mongolia. We also assessed knowledge and attitudes regarding HPV and the HPV vaccine.A retrospective paired cohort study was undertaken to evaluate the effect of a single dose of 4vHPV, given at age 11–17 years in 2012, on HPV detection rates, when compared with unvaccinated women. Real time PCR was performed on self-administered vaginal swabs for HPV detection. An immunological analysis detecting neutralising antibodies (NAb) to high-risk HPV (HRHPV) genotypes 16 and 18 was performed on sera from a subset of 58 participants. Questionnaires evaluated knowledge, attitudes and self-swab acceptability.A total of 475 women (mean age 20.4 years ± 1.6) were recruited; 118 vaccinated and 357 unvaccinated women. The prevalence of vaccine-targeted HRHPV16 and 18 was reduced by 92% (95%CI 44–99%) in the vaccinated (1·1%) compared with the unvaccinated (15.4%) group. The percentage of non-vaccine HPV genotypes was similar between vaccinated (26.5%) and unvaccinated (26.7%) groups. Approximately 90% and 58% of vaccinated women remained seropositive after six years for HRHPV16 and 18, respectively, with neutralising antibody levels 5- and 2-fold higher than unvaccinated women (p < 0.001).One dose of 4vHPV vaccine reduces vaccine-targeted HPV genotypes, six years following vaccination, with high levels of HR genotype seropositivity among young Mongolian women. Combined analyses of both the Costa Rica Vaccine Trial and PATRICIA Trial reported that one dose of 2vHPV could be as efficacious as three doses when using the endpoint of persistent HPV infection accumulated over the four-year trial period The Axios Foundation, through the Millennium Challenge Account, donated 44,800 4vHPV doses to the Mongolian Ministry of Health in 2012 22.1This retrospective paired cohort study was conducted between September 2018 and February 2019. Women were recruited from the Bayangol and Baganuur districts of Ulaanbaatar city and the Umnugobi and Selenge provinces. Unvaccinated participants were also recruited from the Sukhbaatar district of Ulaanbaatar city and Arkhangai province; neighbouring and socioeconomically similar sites. Women who received one dose of 4vHPV in the 2012 pilot vaccination campaign were frequency age-matched to a group of women who never received any HPV vaccine from the appropriate district or province.Recruitment methods were similar to those employed in our previous study All study participants were asked to complete a questionnaire which included demographic characteristics, sexual and reproductive history for information on possible confounders, as well as knowledge and attitudes towards HPV, HPV vaccine and cervical cancer.Participants were requested to collect a self-administered vaginal swab for HPV detection and to complete a short questionnaire regarding the acceptability of this process. Blood samples for serological analysis were sequentially collected from a subset of consenting vaccinated and unvaccinated women within the Bayangol district of Ulaanbaatar. Blood collection was only performed in the capital city to limit time to processing and ensure sample consistency.2.2The first questionnaire utilised semi open-ended questions to collect participant demographics including sexual and reproductive history and relevant lifestyle risk factors. Combined open and closed-ended questions were used to determine participant knowledge and attitudes on HPV, the HPV vaccine and cervical cancer, which was scored based on correct responses. The questionnaire design was based on our larger HPV genoprevalence study conducted between 2017 and 2018 with recipients who received three doses of 4vHPV within the same sites 2.3Self-administered vaginal swabs  were requested from all study participants. The laboratory methods for HPV detection  were conFor the immunological analysis, 5 mL of blood was collected in a serum gel tube from a subset of participants enrolled in Ulaanbaatar . The blood was processed at Onoshmed laboratory, Ulaanbaatar. Serum samples were stored at −80 °C and shipped on dry ice to the Murdoch Children’s Research Institute, Australia for testing. An HPV pseudovirion-based neutralisation assay was used to detect neutralising antibodies (NAb) to HRHPV16 and 18 2.4The primary outcome was defined as detection of HPV high-risk genotype 16 and/or 18 in the vaccinated and unvaccinated groups. Secondary outcomes included; detection of other HRHPV genotypes in the same groups; neutralising antibody titers to HRHPV16 and 18 six years following 4vHPV among a subset of women from each group; knowledge and attitudes of young Mongolian women in relation to HPV, the vaccine and cervical cancer; and the acceptability of self-administered vaginal swabs based on open and closed ended questions.2.5A maximum of 240 one-dose vaccinated women were potentially eligible for enrolment based on immunisation records from the 2012 pilot vaccination campaign. From available HPV prevalence data in Mongolia Categorical demographic variables were summarised as numbers and percentages and continuous variables using means and standard deviations for the vaccinated and unvaccinated groups. Chi squared tests were used to compare differences between the groups. HPV prevalence was assessed by the following genotype sub-groups; all tested high-risk types, vaccine-targeted types 16 and 18 (both together and separately), high-risk types excluding HRHPV16 and 18 and co-detection with multiple genotypes. Prevalence ratios were calculated by comparing the prevalence between vaccinated and unvaccinated groups. Within each HPV sub-group, univariable log-binomial regression models were fitted to estimate unadjusted prevalence ratios of HPV positivity in association with participant characteristics. We evaluated each individual potential confounder to identify those that altered the relevant prevalence ratio by > 5–10% irrespective of statistical significance Statistical analysis was performed using STATA version 15.1. To identify risk factors associated with HPV positivity, univariate and separate unconditional multivariate logistic regression models were used to compare demographic and disease-associated characteristics between participants who tested positive and participants who tested negative for HRHPV16, 18 and other tested HRHPV genotypes.t-test. These analyses were performed using GraphPad Prism software, version 5.0. Our chosen sample size provided 90% power to detect a 30% difference in HPV antibodies with a 2-sided 5% significance level.For the immunological analysis we compared the geometric mean titres (GMTs) of the HPV-specific NAb titres against HRHPV-16, and -18 in girls who previously received one dose of 4vHPV with girls who received no vaccine. NAbs titres were log-transformed and compared using the unpaired Student’s Knowledge-based questions comprised answers of ‘yes’, ‘no’, ‘don’t know’. Participant answers were transcribed in Microsoft Excel and were assigned low, moderate and high scores based on total outcome. Blank answers on an otherwise completed questionnaire were classified as incorrect. Attitudes-based questions allowed for multiple responses 33.1SD = 1.5) and 20.3 (SD = 1.6) years for vaccinated and unvaccinated groups respectively. Around 60% of participants identified as students at the time of enrolment, with a larger proportion (p = 0.007) of students represented in the unvaccinated group  compared to vaccinated . A greater proportion (p = 0.004) of vaccinated participants  indicated a monthly average income in the highest bracket when compared to unvaccinated participants . The majority of participants  had either engaged in sexual intercourse  or genital skin contact with a partner . This was consistent across both groups whereby 82 (69%) vaccinated and 238 (67%) unvaccinated participants had engaged in either sexual intercourse or genital skin contact.The study enrolled a total of 475 women aged 16–26 years; 118 one-dose recipients and 357 unvaccinated women. Participant demographics according to vaccination status are detailed in 3.2Self-administered vaginal swabs were collected from all 475 women for HPV detection. From these, nine swabs returned invalid/error results and were excluded from analysis . A resulPositivity for HRHPV16 and 18 was associated with having two to four lifetime sexual partners  remained seropositive for HRHPV16 and 58% (17) remained seropositive for HRHPV18 after six years. None of the seropositive, vaccinated women had HRHPV16 or 18 detected in vaginal swabs, however eight tested positive for other HRHPV genotypes. Among the 28 blood samples from unvaccinated women, 25% (7) were seropositive to HRHPV16 and 10% (3) seropositive to HRHPV18; all ten were negative for current HRHPV16 or 18 infection. Significantly higher geometric mean NAb titers to HRHPV16 and 18 were observed in one-dose vaccinated women compared with unvaccinated women (HRHPV16: 470.2 (95%CI: 272.2–812.3) vs. 82.0 (95%CI: 56.2–119.8); HRHPV18: 128.9 (95%CI: 86.5–192.2) vs. 56.6 (95%CI: 48.0–66.7)) .Fig. 2Ne3.4The knowledge and attitudes questionnaire results overall were consistent with our previous study A total of 474 participants answered all questions regarding self-swab acceptability. Almost all participants  identified that the self-swab instructions were clear and exhaustive, 389 participants (82.0%) indicated that the technique was easy to conduct and 317 (66.9%) reported they did not experience any pain during the process. A greater number of participants  identified that they would prefer to perform the swab in an outpatient clinic rather than at home.4This study builds on previous follow-up studies of HPV demonstration campaigns The immunogenicity results extend current evidence of persisting immune responses following a single dose of 2vHPV or 4vHPV The questionnaire results were consistent with our larger study with three-dose recipients A limitation of this study was the differential testing methods between the Cepheid and Seegene technology. The original method was based on limited cost-effective technology availability in Mongolia and additional funds were sourced to retest the HRHPV18/45 positive samples only. Additional limitations include the limited sample size of vaccinated women and the fact that girls were self-chosen (or parent-chosen) to receive only one dose of vaccine and we therefore could not account for potential selection bias. However, the sample size was sufficiently powered to demonstrate a difference in HPV detection between the groups. A strength of this study was the consistency in the HPV prevalence and immunogenicity data with the Fiji and Uganda studies Since WHO revised the schedule recommendations for 2vHPV and 4vHPV from three to two doses separated by six months for girls under 15 years 5This study demonstrates that one dose of 4vHPV, administered six years prior, is associated with reduced HPV detection rates and sustained vaccine-type HPV seropositivity among young Mongolian women aged 16–26 years. These results contribute to the emerging global evidence regarding single-dose HPV vaccine schedules. These results are pertinent whilst we await the results of RCTs on one dose in an era of vaccine shortage. The study results also contribute to the limited HPV prevalence data available in Mongolia and demonstrate an acceptance of HPV self-testing among young Mongolian women. The authors foresee the results of this study contributing to greater efforts to reduce the barriers for HPV vaccine uptake in LMICs.6This study was approved by the Ethical Committee of the Mongolian Ministry of Health , the Human Research Ethics Committee (HREC) (Reference Number: HREC/18/RCHM/132) and the Royal Children’s Hospital, Melbourne Human Research Ethics Committee (RCH HREC Reference Number: 38046A).10.13039/100000865Bill & Melinda Gates Foundation (OPP118417). The study sponsor was not involved in any stage of the study design, data collection, analysis or publication process. The corresponding author confirms that she had full access to all study data and had final responsibility for the decision to submit for publication.This study was funded by the CvM, FMR, TB and KM designed the study. KM, CvM, FMR, SMG and US provided scientific input. TB, MM, TK and MTD collected or generated study data. CvM, ZQT and PL conducted data analysis and provided technical statistical input. ZQT, PL and NN provided technical laboratory support. CvM, ZQT, PL and MTD interpreted the data. MTD prepared The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Professor Suzanne Garland (SMG) is a member of 9vHPV Advisory Board, Merck Scientific and Global Advisory Boards. SMG has received Grants through her institution from Merck for HPV studies in young women. All other authors have no conflicts of interest to declare.


N-substituted polyether-block-amide (PEBA-X%) copolymers were prepared by melt polycondensation of nylon-6 prepolymer and polytetramethylene ether glycol at an elevated temperature using titanium isopropoxide as a catalyst. The structure, thermal properties, and crystallinity of PEBA-X% were investigated using nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectroscopy, differential scanning calorimetry, wide angle X-ray diffraction, and thermogravimetric analysis. In general, the crystallinity, melting point, and thermal degradation temperature of PEBA-X% decreased as the incorporation of N-methyl functionalized groups increased, owing to the disruption caused to the structural regularity of the copolymer. However, in N-acetyl functionalized analogues, the crystallinity first dropped and then increased because of a new γ form arrangement that developed in the microstructure. After the cross-linking reaction of the N-methyl-substituted derivative, which has electron-donating characteristics, with poly, the decomposition temperature of the resulting polymer significantly increased, whereas no such improvements could be observed in the case of the electro-withdrawing N-acetyl-substituted derivative, because of the incompleteness of its cross-linking reaction.A series of  PTMEG was heated to 60 °C in a vacuum for 4 h before being used.The polyether-N-acetyl-X%) and nylon-6(N-methyl-X%). All nylon-6 prepolymers and PEBA copolymers were isolated as white to pale yellow powders, and the results are summarized in To a stirred mixture of PTMEG 250  and nylon-6 prepolymer  in a nitrogen-filled environment was added 15 mol% of titanium isopropoxide. The resulting reaction mixture was heated to 230 °C for 4 h. After the reactants have cooled to room temperature, 150 mL of reagent-grade acetone was added and stirred evenly for 4 h. The product was filtered, re-washed with acetone, and dried at 80 °C in a vacuum overnight to obtain 10 g of the polymer (PEBA 250). A similar procedure was adopted for all other PEBA-X% polymers but adding with different functionalized ratios of nylon-6  or nylon-6(N-acetyl-X%) using ring-opening polymerisation with adipic acid as the catalyst. The prepolymers were then made to react with PTMEG of molecular weights 2000 and 250 by esterification to form various PEBA copolymers.1H NMR, 13C NMR, and FT-IR. According to 2CH–CH2–CONH–, A), δ = 1.3 ppm , and δ = 1.4 ppm  correspond to the methylene chemical shifts in the repeat unit; the peaks at δ = 2.0 ppm  to the methylene chemical shift of α position in the amide group; the peaks at δ = 3.0 ppm  to the methylene chemical shift adjacent to the amide group; the peak at δ = 2.1 ppm  to the methylene chemical shift at the α position of the carboxyl group; and the peaks at δ = 7.7 ppm  and δ = 12.0 ppm  to the chemical shifts of the amide hydrogen and terminal carboxylic acid group, respectively. All these shifts are consistent with the nylon-6 structure  and δ = 33.9 ppm , respectively. At δ = 25.1 ppm , δ = 26.1 ppm , δ = 28.9 ppm , δ = 35.4 ppm , and δ = 38.3 ppm , the chemical shifts of carbon in the methylene group of nylon-6 can be observed. The peak at δ = 171.9 ppm  corresponds to the chemical shift of the carbonyl group in the amide group, while those at δ = 174.7 ppm  and 171.9 ppm  correspond to the chemical shifts of the carbonyl group of adipic acid and the amide group of nylon-6, respectively. The results are consistent with what is stated in the literature , δ = 26.1 ppm , and δ = 28.9 ppm . The chemical shift at δ = 32–33 ppm , δ = 171.5–172.0 ppm –; 8, G) and δ = 174.5 ppm  can be attributed to the methyl substituent in nitrogen, the characteristic carbonyl chemical shift of polyamide, and the chemical signal of adipic acid, respectively.As 2CH–CH2–CONH–, 2], δ = 26.2 ppm , δ = 28.9 ppm , δ = 35.4 ppm , and δ = 38.3 ppm  in N-acetyl-caprolactam moieties. The peak at δ = 168.9–171.8 ppm represents the chemical shift of the amide carbonyl group in nylon copolymers, and that at δ = 174.5 ppm  the characteristic chemical shift of the adipic acid end group.The peaks at δ = 25.1 ppm [–N-methyl-X%), and nylon-6(N-acetyl-X%) at 230 °C using different molecular weights of PTMEG with titanium (IV) isopropoxide as the catalyst. The summarised results of the analysis are presented in N-Methyl-30%) and PEBA 250(N-Acetyl-30%) are shown in −1 (C–O–C), which can be attributed to the incorporation of PTMEG.PEBA copolymers are prepared by melt condensation of acid-terminated nylon-6, nylon-6, and PEBA 250(N-acetyl-30%). In H2–CH2O–, E) and δ = 3.2–3.4 ppm  are the signals from PTMEG. Moreover, the peak at δ = 4.0 ppm  represents the chemical shift of a new ester group indicating that esterification had been successful. Likewise, the 1H NMR spectra in N-methyl protons at δ = 2.7 ppm (–N–CH3) and N-acetyl protons at δ = 1.8 ppm (–N–CO–CH3) are also compatible with the structure. The relative content of polyether to polyamide were calculated based on the integrations of ester peak at 4.0 ppm and the methylene chemical shift adjacent to the amide group at 3.0 ppm. The results were summarized in H, M), which is also present in the HMQC spectra of PEBA 250 (2CH–) in 13C NMR whereas δ = 4.4 ppm (–OH) cannot correspond to any point in 13C NMR. Similar results can also be found in N-substituted derivatives indicating that esterification had occurred.The chemical shift at δ = 4.4 ppm was found to be the characteristic peak of the terminal hydroxyl group . This phenomenon was also observed in the product structure of PEBA(N-methyl-X%) (Entries 10–15). Interestingly, in the case of PEBA(N-acetyl-X%), crystallinity first dropped and then increased. Comparing to the PEBA 2000, the crystallinity of PEBA 2000 fell from 57.2% (Entry 8) to 31.3%, 34.9%  and then rebounded to 59.4% (Entry 18). It is presumed that as the proportion of N-acetyl-caprolactam increases, new hydrogen bonding between the carbonyl group of the N-acetyl moiety and the amide group can occur, which can result in a new arrangement of the γ form causing a rebound in the crystallinity. N-methyl-30%), and PEBA 2000(N-acetyl-30%). As the figure shows, all samples exhibited diffractions at 2θ = 20.3 and 24.0, which correspond to the crystalline phase of the nylon-6 matrix; however, a small diffraction peak at 2θ = 21.5° was observed for PEBA 2000(N-acetyl-30%), which can be attributed to the γ crystalline form in the microstructures [Nylon-6 is a semi-crystalline polymer, whose crystalline phase can be divided into two phases: Phase α and Phase γ. The α crystalline phase 2θ: 20°, 23–24°) is mainly a fully extended or twisted nylon-6 structure and is arranged in an antiparallel fashion, while the γ crystalline phase 2θ: 21°) is the result of the amide group forming hydrogen bonds at a bond angle of 60° ,20. Acco°, 23–24°° is the ructures .N-methyl-X%) (Entries 13–15), and PEBA 250(N-acetyl-X%) (Entries 19–21), the crystallinity of N-methyl fell from 74.3% (Entry 9) to 71.8%, 48.3% and 35.4% (Entries 13–15) as the substituent ratio was increased, whereas in N-acetyl cases, the crystallinity of PEBA 250 fell from 74.3% (Entry 9) to 54.2%, 57.0%  and then rebounded to 79.7% (Entry 21).A similar phenomenon could also be observed in the PEBA 250 series; in PEBA 250 (Entry 9), PEBA 250(Tm) of nylon-6(N-methyl-X%) prepolymer decreases from 185 °C (Entry 1) to 178, 175 and 157 °C (Entries 2–4), whereas that of nylon-6(N-acetyl-X%) prepolymer (Entries 5–7) first decreases from 185 to 165 °C and then increases from 165 to 170 °C. This downward trend of the melting point is consistent with the change in crystallinity. With regard to thermal stability, the thermogravimetric analysis shows that Td,5% falls as the proportion of the substituent monomer is increased. The principal degradation mechanism is generally believed to begin with the scission of the C(O)–NH bonds [2–CON–2CH–) in nylon is the least stable and is expected to break first. Because of the bond-dissociation energy of small molecules, the N–C bond-dissociation enthalpies (DHo298) of H2N–C(O)H stands at 413.7 kcal/mol, which is slightly higher than that of either N-methyl (CH3N–C(O)H) bond  or N-acetyl (H2N–C(O)CH3) bond  series (Entries 10–15), the melting points fell as the proportion of methyl-caprolactam monomer was increased. PEBA 250(N-methyl-30%) exhibited the most notable reduction in the melting point, which was as low as 157 °C. Thus, it can be considered for applications requiring low melting and foaming temperatures in scale up production, which justifies its use in the subsequent cross-linking reactions. In the series of PEBA(N-acetyl-X%) (Entries 16–21), the decomposition temperature  decreased with the incorporation of the acetyl-caprolactam group; however, this temperature showed an upward trend as the proportion of the acetyl-caprolactam content was increased. For example, unlike the Td,5% of PEBA 2000 (Entry 8), the Td,5% of PEBA 2000(N-acetyl-X%) first fell from 332 °C to 277 °C (Entry 16) and then rose to 285 °C (Entry 18). Likewise, in comparison with the Td,5% of PEBA 250 (Entry 9), the Td,5% of PEBA 250(N-acetyl-X%) first fell from 350 °C to 220 °C (Entry 19) and then increased to 253 °C (Entry 21). The trend of the decomposition temperature is similar to the trend of the crystallinity. In particular, although the regular arrangement of the original nylon-6 was disturbed by the introduction of the acetyl functional group as the proportions of the substituent monomers were increased, the acetyl functional group was responsible for the increase in the crystallinity of PEBA 2000(N-acetyl-30%) caused by intramolecular hydrogen bonding. Consequently, the thermal properties of PEBA 2000(N-acetyl-30%) also improved. It was also observed that the molecular weight of PTMEG affects the thermal properties of PEBA. The higher the molecular weight of PTMEG, the higher is the thermal stability of N-substituted nylon elastomers. With regard to Td,5%, the molecular weight of PTMEG had a higher influence on N-methyl functionalized PEBA than that of any N-acetyl functionalized analogue. When the 10% substituted group  is considered as an example, the Td,5% of PEBA 250(N-methyl-10%) and PEBA 250(N-acetyl-10%) were 71 and 57 °C lower than the Td,5% of PEBA 2000(N-methyl-10%) and PEBA 2000(N-acetyl-10%), respectively. As for the groups with 20% substitution , the difference increased to 120 and 29 °C and for the group with 30% substitution, the difference increased to 116 and 32 °C (Entries 13 vs. 16 and 19 vs. 22). Similar results were observed with regard to the melting points. With the group with the same percentage substitution, the molecular weight of PTMEG and the Tm of the nylon elastomers were lower.In the PEBA(N-methyl-30%) and PEBA 250(N-acetyl-30%) which have a low melting point for chemical cross-linking with poly (PMDI). A good cross-linking reaction can improve the mechanical strength of the elastic foaming materials and enable the melt to stay stable during foaming without letting the cells burst. To meet the requirements pertaining to low-temperature foaming, we chose elastomers made of PEBA 250(N-methyl-30%)-PMDI and PEBA 250(N-acetyl-30%)–PMDI. As N-methyl-30%)–PMDI has a new absorption peak at 1707 cm−1, which can be attributed to the formation of carbamate , while the new peaks at 1599 cm−1 and 1511 cm−1 correspond to the carbamide C–N stretching and C–H bending, respectively [−1 can be assigned to ether linkages  in PMDI after the cross-linking reaction has occurred. Similarly, in −1 also confirm that cross-linking reactions had occurred. After the cross-linking reaction, the Td,5% of PEBA 250(N-methyl-30%)–PMDI significantly increased by 78 °C, i.e., from 199 to 277 °C, while the Td,5% of PEBA 250(N-acetyl-30%)–PMDI increased only by 6 °C, i.e., from 253 to 259 °C (N-Methyl-30%)–PMDI and therefore exhibit no obvious phase transition.The cross-linking reaction was carried out in an argon-filled environment under molten conditions. The temperature was slowly increased from 160 to 165 °C to melt the PEBA, following which 30–37 wt% of PMDI (NCO content 23%) was added and stirred evenly for 15 min. Heating was then stopped, while maintaining the argon-filled environment to enable cooling. The product was purified by thorough wash with acetone and isolated as brownish yellow solid in quantitative yield after drying by vacuum for 2 h. The swelling ratio of the cross-linked polymer was estimated 150% after stirring the samples with DMSO for 15 h at 25 °C. ectively . The newo 259 °C .. It is N-methyl-30%)–PMDI has no distinct melting point, which indicates that the crystal structure has broken during the cross-linking reactions, whereas PEBA 250(N-acetyl-30%)–PMDI continues to exhibit the melting point at 149 °C, confirming that its cross-linking reaction is incomplete.The acetyl-substituted group has electro-withdrawing characteristics, which decrease the nucleophilicity of amide nitrogen, thereby making it more difficult for the cross-linking reactions to take place, while the methyl-substituted group has electro-donating characteristics, which increase the nucleophilicity of amide nitrogen, enabling cross-linking reactions to take place successfully. The DSC results also show that PEBA 250 series, because the N-acetyl functional group can also form intramolecular hydrogen bonds as the proportion of the substituent monomers is increased, the crystallinity of the product first decreases and then increases. The rebound in crystallinity can be attributed to the new intramolecular hydrogen bonding formed, which can produce a new arrangement of the γ crystalline form in the polymer, as shown by the XRD. A similar trend can also be observed in their pyrolysis temperatures. After the cross-linking reaction with PMDI, the Td,5% of PEBA 250(N-methyl-30%) increased by 78 °C, whereas that of PEBA 250(N-acetyl-30%) did not show such a notable increase indicating that the electro-donating group can increase the nucleophilicity of nitrogen, which will be beneficial to cross-linking reactions. In contrast, the electro-withdrawing group can reduce the nucleophilicity of nitrogen and thereby adversely affect the cross-linking reaction.In this study, we have successfully synthesized a series of new