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BackgroundThis study investigated circumstances of initiating new-type drug use among adult new-type drug users and differences among those who first used methamphetamine, ecstasy and ketamine.MethodsA total of 276 participants were recruited, using respondent-driven sampling (RDS) from nine seeds recruited through NGOs, social workers and outreach workers in Shanghai, China.ResultsMethamphetamine was the most frequently reported first new-type drug used (37.1%), followed by ecstasy (35.6%) and ketamine (20.0%). 38.7% of participants initiated new-type drug use before the age of 21 years. 47.8% knew at initiation that club drugs can be harmful. Most were introduced to new-type drug use by friends, spouses or boy/girlfriends. The three most common reasons for initiation were curiosity, peer influence, and wishing to dull one's emotions. Those first using methamphetamine were more likely to be female, have a monthly individual income less than 3000 Yuan (approx. $476), initiate use at 21 years or older and at private setting than those first using ecstasy and ketamine.ConclusionsThere is an urgent need for drug education efforts in China to raise awareness of the harms of new-type drugs, as well as to increase knowledge about the paradox of new-type drug effects. Drug prevention and intervention programs should be tailore to target populations and their social context.

AbstractBackgroundContact tracing is especially useful for identifying an infection with few cases in the population, such as HIV in China. Little such research is available in China.MethodsEvery newly diagnosed HIV case from 2008–2010 in Taizhou Prefecture, Zhejiang Province in China, was invited to participate as an “index case” in a contact tracing survey by providing contact information for up to eight sexual contacts who themselves were approached for voluntary HIV counseling and testing (VCT). Those who tested HIV-positive were then subjected to another contact tracing survey. This process was repeated until no more sexual contacts were reported or tested positive.ResultsA total of 463 HIV-infected individuals were newly identified during the study period, including 338 cases who were identified from routine surveillance programs and 125 cases who were identified from the present contact tracing survey. Among these 463 cases, 398 (86.0%) served as ‘index cases’ in the survey, including 290 (85.8%) out of the 338 cases identified from routine surveillance programs and 108 (86.4%) out of the 125 cases identified from the present survey. These 398 ‘index cases’ reported a total of 1,403 contactable sexual contacts, of whom 320 (22.8%) received HIV testing and 125 (39.1%) tested positive for HIV. Willingness to receive HIV testing was high among spouses and long term heterosexual or homosexual partners but extremely low among casual and commercial sex partners of ‘index cases’. Consistent condom use was rare for all participants. A total of 290 independent sexual network components were constructed, with high complexity.ConclusionContact tracing is useful for identifying new HIV infections from spouses or long term sexual partners of HIV-infected individuals. The complicated sexual networks existing between and beyond HIV-infected persons provide opportunities for rapid spread of HIV in such areas.

Recently, two-dimensional (2D) piezoelectric materials are widely studied, and the vertical piezoelectric properties of 2D materials are highly required to be known in the related theory research works and experiments, so it becomes very important to explore the intrinsic mechanism of piezoelectricity in the 2D materials. Herein, we systematically study the piezoelectricity of Janus C3HFX (X = Si and Ge) monolayers with semiconductor property, which are carbon-based 2D materials, using the first-principles calculation. The remarkable enhancements on the absolute values of the vertical piezoelectric coefficient of C3HFSi-1 (e33 = 11.27 × 10−10 C/m) and C3HFGe-4 (e33 = −12.78 × 10−10 C/m) are larger than that of C4HF (e33 = −2.28 × 10−10 C/m) by 5 and 6 times, respectively. It indicates that the atom replacement at appropriate positions in the multiatomic monolayer can significantly enhance the vertical piezoelectric properties based on the appropriate distribution of polarization charge. We define the concepts, the Born effective charges center (BECs-center) and the BECs-dipole-moment in this work, to explain these large vertical piezoelectric coefficients' variation. The larger BECs-dipole-moment will enhance the vertical piezoelectricity for these C3HFX monolayers than that of the C4HF monolayer. These concepts defined in this work will deepen the understanding of the internal physical mechanism about the piezoelectricity. [ABSTRACT FROM AUTHOR]

Background Frailty is one of the major concerns among aging people with HIV (PWH). Evidence regarding the association between sleep disorders and physical frailty in PWH is limited. Methods PWH and HIV-negative individuals aged ≥40 years were included and frequency-matched in a 1:2 ratio by sex and age. Logistic regression models were used to estimate the odds ratios (ORs) and 95% CIs of the association between sleep disorders and physical frailty, and restricted cubic splines were used to describe the dose–response association. The contribution of depression to the association was estimated by mediation analysis. Results A total of 1526 PWH and 3052 HIV-negative individuals were included. Logistic regression indicated that insomnia (OR, 3.05; 95% CI, 1.63–5.72) and poor sleep quality (OR, 2.32; 95% CI, 1.21–4.45) were significantly associated with physical frailty in middle-aged and older PWH, especially in those with current CD4+ T-cell counts <350 cells/µL, but not in HIV-negative participants. A U-shaped and J-shaped dose–response relation between sleep duration and physical frailty was observed in PWH and HIV-negative participants, respectively. Shorter and longer sleep duration was associated with an increased risk of physical frailty in PWH. However, in HIV-negative participants, only longer sleep duration was associated with physical frailty. Mediation analysis revealed that depression mediated the relation between sleep disorders and frailty among PWH. Conclusions Sleep disorders including insomnia, poor sleep quality, and short and long sleep duration were significantly associated with physical frailty among middle-aged and older PWH. Depression may play a mediating role in the sleep–frailty association. [ABSTRACT FROM AUTHOR]

During the construction of a diversion tunnel, geological problems often include faults, fragile strata, hard rock formations, karst landforms, etc., which may have adverse effects on the excavation and construction of the diversion tunnel. Based on the analysis of the engineering overview, this study designed a new construction technology for the excavation of water diversion tunnels in hard rock layers and high-karst areas. Based on tunnel seismic prediction (TSP) technology to achieve advanced geological prediction, combined with actual geological conditions, construction difficulties are analyzed. Then, detection technology is used to collect two-way travel time, amplitude, and waveform data. By processing and analyzing the detection image, the spatial orientation and length of the main tunnel during the construction of the diversion tunnel are calculated. After completing the construction ventilation and wind, water, and electricity layout, the excavation construction procedure is designed. In the specific excavation design, the tunnel curtain excavation technology, tunnel body excavation and support technology, excavation grouting technology, important unfavorable geological tunnel section excavation technology, upper/lower flat section excavation technology, upper/lower curved section excavation technology, and vertical shaft section excavation technology were elaborated. Finally, a plan was made for the reuse process of slag material and a construction quality control system was established. During the testing process, it was found that the antidamage coefficient of the side wall was above 0.9 after using the technology described in this article. Therefore, it indicates that the excavation construction technology designed in this article can ensure the support capacity of the side wall of the diversion tunnel, which is suitable for the excavation of the main tunnel during the construction of the diversion tunnel. [ABSTRACT FROM AUTHOR]