The development of a sub-atmospheric two-phase thermosyphon natural gas preheater using a lumped capacitance model and comparison with experimental results

The pre-heating of natural gas supplied to both domestic and industrial use is required to counteract the Joule–Thomson effect due to pressure reduction. Most existing pre-heaters are in the form of water bath heaters, where both the burner and exchanger are immersed in a closed water tank. These systems usually have a low efficiency, and as a result of thermal inertia have a long time lag to accommodate changes in Natural Gas (NG) mass flow rates. In this paper, the two-phase thermosyphon theory is implemented in a sub-atmospheric context to design and study a new preheating system in a transient fashion. This system is partially vacuumed (absolute pressure of 2 kPa) to lower the temperature operation range to reduce the required working fluid volume, hence reduce the required energy and improve the response time. The transient numerical model is based on a lumped capacitance method, and the full system is solved by using a fourth order Runge–Kutta method. The numerical model is validated through comparison with experimental results. Minimum efficiency of 68% has been achieved in some tests, whilst maximum efficiency of 80% in other tests. Simulations of the thermosyphon preheater system have been performed to analyse the effect of changing the working fluid volume and composition

Extended HPV genotyping to compare hpv type distribution in self- And provider-collected samples for cervical cancer screening

Background: Primary high-risk human papillomavirus (hr- HPV) testing of self-collected cervico-vaginal swabs could increase cervical cancer screening coverage, although triage strategies are needed to reduce unnecessary colposcopies. We evaluated the use of extended hr-HPV genotyping of self-collected samples for cervical cancer screening. Methods: We recruited women ages 25-65 years at two colposcopy clinics in North Carolina between November 2016 and January 2019, and obtained self-collected cervico-vaginal samples, providercollected cervical samples, and cervical biopsies from all enrolled women. Self- and provider-collected samples were tested for 14 hr- HPV genotypes using the Onclarity Assay (Becton Dickinson). We calculated hr-HPV genotype-specific prevalence and assessed agreement between results in self- and provider-collected samples. We ranked the hr-HPV genotypes according to their positive predictive value (PPV) for the detection of cervical intraepithelial neoplasia (CIN) grade 2 or higher (CIN2+). Results: A total of 314 women participated (median age, 36 years); 85 women (27%) had CIN2+. More women tested positive for any hr-HPV on self-collected (76%) than on provider- collected samples (70%; P = 0.009) with type-specific agreement ranging from substantial to almost perfect. HPV-16 was the most common genotype in self-collected (27%) and provider-collected samples (20%), and HPV-16 prevalence was higher in self- than provider-collected samples (P < 0.001). In self- and provider-collected samples, HPV-16 had the highest PPV for CIN2+ detection. Conclusions: Overall sensitivity for CIN2+ detection was similar for both sample types, but the higher HPV-16 prevalence in self-collected samples could result in increased colposcopy referral rates. Impact: Additional molecular markers might be helpful to improve the triage of women who are hr-HPV positive on selfcollected samples

Knowledge, beliefs and barriers associated with prostate cancer prevention and screening behaviors among African-American men.

African-American men have the highest prostate cancer rates worldwide, and innovative efforts are needed to increase cancer prevention and screening behaviors among this population. Formative research was conducted to assess attitudes and behaviors linked to prostate cancer prevention activities that could be used to develop a culturally relevant intervention for an African-American church-based population. Four gender-specific focus groups were conducted with 29 men and women at two African-American churches in central North Carolina. Three primary themes emerged from the focus group discussions: culturally and gender-influenced beliefs and barriers about cancer prevention and screening; barriers related to the healthcare system: and religious influences, including the importance of spiritual beliefs and church support. These discussions revealed the importance of the black family, the positive influence of spouses/partners on promoting cancer screening and healthy behaviors, the roles of faith and church leadership, and beliefs about God's will for good health. These findings also revealed that there are still major barriers and challenges to cancer prevention among African Americans, including continued mistrust of the medical community and negative attitudes toward specific screening tests. Findings provide important insights to consider in implementing successful prostate cancer prevention interventions designed for church-based audiences