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It is crucial to develop novel metrology techniques in the semiconductor fabrication process to accurately measure a film’s thickness in a few nanometers, as well as the material profile of the film. Highly uniform trichlorosilane (1H,1H,2H,2H-perfluorodecyltrichlorosilane, FDTS) derived SAM film patterns were fabricated by several conventional semiconductor fabrication methods combined, including photolithography, SAM vapor deposition, and the lift-off technique. Substantial information can be collected for FDTS SAM film patterns when Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) techniques are incorporated to investigate this material. Precise two-dimensional (2D) FDTS SAM film patterns were reconstructed through mapping analysis of corresponding elements and chemical state peaks by AES and XPS. Additionally, three-dimensional (3D) FDTS SAM film patterns were also reconstructed layer by layer through gas cluster ion beam (GCIB) etching and XPS analysis. These characterization results demonstrate that FDTS SAM film patterns based on the vapor deposition method are highly uniform because the vacuum and precise gas-delivery system exclude ambient environmental interference efficiently and ensure reaction process repeatability. AES and XPS techniques could be used for metrology applications in the semiconductor process with high-quality SAM microstructures and nanostructures.

Droplet microfluidics is becoming an enabling technology for synthesizing microscale particles and an effective real-time method is essential to monitor the variations in a dynamic droplet generation process. Here, a novel real-time cosine similarity algorithm (RT-CSA) method was developed to investigate the droplet generation process by measuring the droplet generation frequency continuously. The RT-CSA method uses a first-in-first-out (FIFO) similarity vector buffer to store calculated cosine similarities, so that these cosine similarities are reused to update the calculation results once a new frame is captured and stored. For the first time, the RT-CSA method achieved real-time monitoring of dynamic droplet generation processes by updating calculation results over 2,000 times per second, and two pre-microgel droplet generation processes with or without artificial disturbances were monitored closely and continuously. With the RT-CSA method, the disturbances in dynamic droplet generation processes were precisely determined, and following changes were monitored and recorded in real time. This highly effective RT-CSA method could be a powerful tool for further promoting research of droplet microfluidics.

A novel flexible mixed-potential-type (MPT) sensor was designed and fabricated for NO2 detection from 0 to 500 ppm at 200 °C. An ultra-thin Y2O3-doped ZrO2 (YSZ) ceramic film 20 µm thick was sandwiched between a heating electrode and reference/sensing electrodes. The heating electrode was fabricated by a conventional lift-off process, while the porous reference and the sensing electrodes were fabricated by a two-step patterning method using shadow masks. The sensor’s sensitivity is achieved as 58.4 mV/decade at the working temperature of 200 °C, as well as a detection limit of 26.7 ppm and small response time of less than 10 s at 200 ppm. Additionally, the flexible MPT sensor demonstrates superior mechanical stability after bending over 50 times due to the mechanical stability of the YSZ ceramic film. This simply structured, but highly reliable flexible MPT NO2 sensor may lead to wide application in the automobile industry for vehicle emission systems to reduce NO2 emissions and improve fuel efficiency.

This study aimed to investigate the association between early sexual initiation and suicide attempts (SAs) among Chinese young people. Our analysis included 9131 college students who had sexual experience from a national sample of 31 provincial administrative regions. Self-reported age at first intercourse was categorized as ≤15, 15-18, and ≥18 years, and the experience of SAs was recorded and analyzed. Compared with females whose sexual debut age was ≥18 years, those ≤15 years (defined as early sexual initiation) had higher odds of SAs in both the forced debut group (odds ratio (OR) 17.04, 95% confidence interval (CI) 4.87-59.66) and the voluntary debut group (OR 37.63, 95% CI 14.96-94.66). Early sexual initiators who lived in rural areas were more inclined to have SAs (female: OR 65.76, 95% CI 19.80-218.42; male: OR 15.39, 95% CI 1.64-144.19). Early sexual initiators who never had parent-child communication about sex were more likely to report having SAs (female: OR 37.81, 95% CI 12.28-116.46). Sexual debut during adolescence, particularly early sexual initiation, was a crucial risk factor for SAs among both sexes. Comprehensive sexuality education and smooth parental communication about sex will provide a supportive environment for young people and hence reduce the potential risks of SAs.

Background: College students are at-risk populations of mental health problems and risky sexual behaviors. However, little literature focuses on the association between mental health problems and risky sexual behaviors. Our study examined the association between mental health problems (depressive symptoms, suicide, and mental disorders) and risky sexual behaviors among a large sample of Chinese college students., Methods: A total of 49,728 Chinese college students (47.5% male) eventually participated in the analysis. A self-administered questionnaire was used to measure mental health, risky sexual behaviors (casual sex, no condom use at last sexual intercourse, group-sex, and a high number of sexual partners), and other sociodemographic characteristics. Logistic regression analysis was used to explore the relationship between mental health and risky sexual behaviors. To ensure the data is representative of the nation's statistics, all analyses were weighed., Results: The prevalence of depressive symptoms, suicide ideation and suicide attempts, and mental disorders was 42.83%, 41.29%, and 7.74%, respectively. 26.13% of participants were sexually active in the previous twelve months. Nearly 35% of sexually active participants were engaged in risky sexual behaviors. Logistic regression results demonstrated that mental health problems were associated with risky sexual behaviors after adjusting confounders., Limitations: cross-sectional analysis; The self-reported variables may be subject to recall bias and fraud., Conclusions: There is a relatively high prevalence of mental health problems and risky sexual behaviors amongst Chinese college students. A significant association between mental health problems and risky sexual behaviors was suggested by our study. Our findings support the importance of advocating for mental and reproductive healthcare for college students., (Copyright © 2021. Published by Elsevier B.V.)

Background: Chinese youth have become more sexually active over the years, yet their behaviours of contraceptive use are influenced by socioeconomic and lifestyle factors. This study aimed to investigate the socioeconomic and lifestyle determinants of contraceptive use among Chinese college students, and to investigate quantitatively their reasons for choosing different contraceptive methods., Methods: The study used the data from a cross-sectional survey, which was conducted in 2015 among 17,517 students from 130 colleges and professional schools in mainland China. Chi-square tests were performed to test the differences in the awareness and uses of contraceptives between male and female students. Multivariable logistic regression models were used to analyse the associations between socioeconomic and lifestyle factors and contraceptive uses., Results: Condoms (95%), oral contraceptives (91%) and emergency contraceptives (71%) were the most commonly known contraceptive methods among the sample of Chinese youth that were surveyed. Among male participants, high monthly expenditure (OR = 1.37, 95%CI: 1.07-1.75), light alcohol consumption (OR = 1.47, 95%CI: 1.03-2.11), and high sexual knowledge (OR = 1.96, 95%CI: 1.57-2.45) were positively associated with contraceptive uses, while tobacco use (OR = 0.47, 95%CI: 0.23-0.95) showed a negative association with contraceptive uses. Among female students, suburban residency (OR = 1.38, 95%CI: 1.03-1.83), high level of parental education (OR = 1.96, 95%CI: 1.19-3.22), moderate alcohol consumption (OR = 2.66, 95%CI: 1.05-6.77), and high sexual knowledge (OR = 1.50, 95%CI: 1.18-1.91) were positively associated with contraceptive uses, while tobacco use (OR = 0.60, 95%CI: 0.36-0.99) showed a negative association., Conclusions: A series of socioeconomic and lifestyle factors were associated with contraceptive choices among Chinese college students. Targeted sexual education programs are in demand to improve the awareness and the use of contraceptives in this population.

An amendment to this paper has been published and can be accessed via the original article.

Objective: To investigate the association between maternal education and breast feeding in the Chinese population, with a consideration of household income and health-seeking behaviours., Design: A nationally representative population-based cross-sectional study., Setting: 77 counties from 12 geographically distinct regions in China., Participants: 10 408 mothers with children from 0 to 12 months of age, aged 15-53 years old (mean: 29.15, SD: 5.11) were classified into primary school or below group (n=781), middle school group (n=3842), high school/vocational school group (n=1990), college or above group (n=3795), according to their highest completed education., Outcomes: Five breastfeeding outcomes, including early initiation of breast feeding (EIB), exclusive breast feeding (EBF) under 6 months, predominant breast feeding under 6 months, current breast feeding and children ever breast fed, were calculated based on the standardised questionnaire from the WHO and Wellstart International's toolkit for monitoring and evaluating breastfeeding activities., Results: The absolute risk of EIB and EBF in the lowest maternal education level was 64.85% and 26.53%, respectively, whereas the absolute risk of EIB and EBF in the highest maternal education level was 77.21% and 14.06%, respectively. A higher level of maternal education was positively associated with EIB (risk ratio (RR): 1.22; 95% CI: 1.12 to 1.30) and was inversely associated with EBF (RR: 0.59; 95% CI: 0.38 to 0.88). Stratified by household income, a positive association with EIB was observed only in the group with the highest household income and an inverse association with EBF was found in both low household and high household income groups., Conclusions: Mothers with a higher education were more likely to initiate early breast feeding when they were also from a high-income household while also being less likely to exclusively breast feed their babies. Routine and successful nursing is crucial for the health of infants and is influenced by maternal education. Future public health interventions to promote breast feeding should consider the issues related to the educational level of mothers., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY. Published by BMJ.)

Background: Breastfeeding rates remain low in China and some mothers stop breastfeeding shortly after returning to work. Our study aimed to investigate the association between breastfeeding practices of working mothers and their employment status (formal versus informal) and occupational fields (agriculture related, industry related, and business and white collar). We also identified key work-related factors that influence breastfeeding practices in Chinese working mothers., Methods: This is a mixed-method research consisted of two components. We conducted a cross-sectional study of 10,408 breastfeeding mothers with children under 12 months old from 12 regions in China from July 2017 to January 2018. Multiple logistic regression was used to calculate adjusted odds ratios (AdjORs) and 95% confidence intervals (CIs) for breastfeeding practices. For the qualitative component, semi-structured interviews were conducted with 84 breastfeeding mothers in the study areas from July to December 2017, Content analysis was used for the qualitative component., Results: Agriculture related occupations were positively associated with early initiation of breastfeeding (AdjOR 1.32, 95% CI 1.15, 1.51), current breastfeeding (AdjOR 1.76, 95% CI 1.41, 2.20), ever breastfed (AdjOR 1.69, 95% CI 1.09, 2.62), exclusive breastfeeding (AdjOR 1.30, 95% CI: 1.04, 1.62), and predominant breastfeeding (AdjOR 1.72, 95% CI 1.44, 2.05). Business and white collar occupations were positively associated with early initiation (AdjOR1.38, 95% CI 1.23, 1.56) and ever breastfed (AdjOR 1.64, 95% CI 1.12, 2.39), and inversely associated with predominant breastfeeding (AdjOR 0.81, 95% CI 0.68, 0.95). For industry related and business and white collar occupations, informal employment was negatively related to current breastfeeding. In qualitative analysis, four main themes were developed to identify key work-related factors that influence breastfeeding practices: 1) employment benefits; 2) commute time; 3) workplace environment; 4) labor intensity. Mothers who experienced difficulties in one or more of the above would choose to lower breastfeeding frequency or stop breastfeeding., Conclusions: Having flexible work schedules and proximity of workplace to home can assist continuance of breastfeeding. Policies promoting supportive breastfeeding environment at work ought to be implemented. Additionally, informally employed mothers require more attention due to limited legal protection., Competing Interests: Competing interestsThe authors declare no competing interests.

Background: A growing prevalence of unexpected pregnancies and younger age of sexual debut is observed among Chinese young people, while they lack formal sexuality education from schools and parents. It is necessary to measure their knowledge level of sexual and reproductive health, and how such knowledge associates with their sexual behaviors and reproductive health outcomes, which would shed light on the effectiveness of sexuality education in China., Methods: An Internet-based questionnaire survey was conducted from January to August, 2015. 130 colleges were selected from eastern, central, and western parts China with a good balance of geographic distributions. The survey link was subsequently delivered to the focal points in each college for voluntary participation, targeting on undergraduates aged 18 ~ 25. Information on demographics, experience of school-based sexuality education (defined as any course introducing information on sexual and reproductive health) and SRH knowledge quiz was collected. Multivariate linear regression and logistic regression were applied to explore the relationship between students' SRH knowledge, sexual behaviors and reproductive health outcomes, such as sexual intercourse (penetrative sex by vaginal or anal), unprotected sex, pregnancy and abortion, etc., Results: A total sample of 17,966 Chinese college students (mean age = 20.2, 60.4% female) eventually entered the analysis. Only 55.6% of the respondents self-reported having received sexuality education before, and they scored significantly higher (2.33/4.00) in the SRH knowledge quiz than those who had not (1.75/4.00). Among the sexually experienced students (n = 3639, 20.2%), both males and females with higher SRH knowledge were less likely to report having experience of (partner's) pregnancy or abortion (OR < 1, p < 0.05). In the group of sexually experienced males, those with higher SRH knowledge had a slightly later age of sexual debut (coefficient = 0.28, p < 0.001), and were less likely to have unprotected sex during the last or in most sexual intercourses (OR = 0.82, 95%C.I.: 0.69 ~ 0.96)., Conclusion: Students' experience of school-based sexuality education may be positively associated with their SRH knowledge level as well as with their sexual behaviors and reproductive health outcomes, but such associations were stronger among males than females. A more effective implementation of school-based sexuality education needs to be scaled up, and a gender-sensitive education strategy to different needs is desirable for SRH promotion among Chinese young people.