Flexible optoelectronic devices attract considerable attention due to their prominent role in creating novel wearable apparatus for bionics, robotics, health care, and so forth. Although bulk single-crystalline perovskite-based materials are well-recognized for the high photoelectric conversion efficiency than the polycrystalline ones, their stiff and brittle nature unfortunately prohibits their application for flexible devices. Here, we introduce ultrathin single-crystalline perovskite film as the active layer and demonstrate a high-performance flexible photodetector with prevailing bending reliability. With a muchreduced thickness of 20 nm, the photodetector made of this ultrathin film can achieve a significantly increased responsivity as 5600A/W, 2 orders of magnitude higher than that of recently reported flexible perovskite photodetectors. The demonstrated 0.2 MHz 3 dB bandwidth further paves the way for high-speed photodetection. Notably, all its optoelectronic characteristics resume after being bent over thousands of times. These results manifest the great potential of single-crystalline perovskite ultrathin films for developing wearable and flexible optoelectronic devices.

Plasmonic color filtering and color printing have attracted considerable attention in recent years due to their supreme performance in display and imaging technologies. Although various color‐related devices are designed, so far very few studies have touched the topic of dynamic color generation. In this article, dynamic color generation is demonstrated by integrating plasmonic nanostructures with vanadium dioxide based on its tunable optical properties through insulator–metal transition. Periodic arrays of silver nanodisks on a vanadium dioxide film are fabricated to realize different colors, relying on the excitation of localized and propagating surface plasmons, and Wood's anomaly. By tuning spatial periodicity of the arrays and diameter of the silver nanodisks, various colors can be achieved across the entire visible spectrum. Further, using insulator–metal transition of vanadium dioxide, the colors can be actively tuned by varying temperature. The approach of dynamic color generation based on the phase transition of vanadium dioxide can easily realize diverse color patterns, which makes it beneficial for display and imaging technology with distinct advantages of multifunctionality, flexibility, and high efficiency.

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The path toward Li-ion batteries with higher energy densities will likely involve use of thin lithium (Li)-metal anode (<50 µm thickness), whose cyclability today remains limited by dendrite formation and low coulombic efficiency (CE). Previous studies have shown that the solid–electrolyte interface (SEI) of the Li metal plays a crucial role in Li-electrodeposition and -stripping behavior. However, design rules for optimal SEIs are not well established. Here, using integrated experimental and modeling studies on a series of structurally similar SEI-modifying model compounds, we reveal the relationship between SEI compositions, Li deposition morphology, and CE and identify two key descriptors for the fraction of ionic compounds and compactness, leading to high-performance SEIs. We further demonstrate one of the longest cycle lives to date (350 cycles for 80% capacity retention) for a high specific-energy Li||LiCoO2 full cell (projected >350 watt hours [Wh]/kg) at practical current densities. Our results provide guidance for rational design of the SEI to further improve Li-metal anodes.

Cu/SiO 2 catalysts were prepared by separate impregnation and deposition precipitation methods for the hydrogenation of dimethyl oxalate (DMO) to ethylene glycol (EG). XRD, TEM, H 2 -TPR, SEM, EDS and N 2 physisorption were performed to characterize the textural and structural properties of the catalysts. The results showed that Cu particles from the deposition precipitation preparation were homogeneously dispersed on the support and their sizes were found to be smaller than those from the impregnation method and the catalyst produced by the deposition precipitation method gave higher EG yields at lower reaction temperatures and lower H 2 /DMO mole ratio.

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ObjectivesThe purpose of the study was to investigate the incidence of HIV and syphilis and their related factors, as well as to examine the predictors associated with seroconversion among migrant men who have sex with men (MSM) in Beijing, China.DesignProspective cohort study.SettingBeijing, China.Participants511 HIV-negative migrant MSM.Primary and secondary outcome measuresSociodemographic and behavioural information of participants, HIV and syphilis incidence rates, and factors associated with HIV/syphilis seroconversion and cohort retention.ResultsOf the 511 participants, 60.3% (308) and 52.4% (273) were retained at the 4- and 8-month follow-up visits, respectively. The HIV and syphilis incidence rates were 7.83 (95% CI 4.48 to 12.72) and 11.11 (95% CI 6.47 to 17.80) per 100 person-years, respectively. HIV seroconversion was significantly associated with ‘had first anal intercourse at age 15 or younger’ (adjusted HR (aHR) 9.20, 95% CI 1.94 to 43.56) and ‘ever had group sex’ (aHR 4.30, 95% CI 1.40 to 13.18). Bisexual orientation (aHR 5.09, 95% CI 1.02 to 25.57) was significantly associated with syphilis seroconversion. Predictors associated with both 4- and 8-month retention rates included age ≥25 years old and living in Beijing for more than 1 year.ConclusionsThe high incidence of HIV and syphilis among migrant MSM is a cause for concern. A comprehensive strategy should be implemented to maintain a higher retention rate among migrant MSM.

ObjectiveThe goal of this study was to understand the knowledge about AIDS, identify the correlates and determine the prevalence of HIV infection, syphilis, HCV among migrant workers in Zhejiang, China.MethodsA cross-sectional study using face-to-face anonymous questionnaire interviews was conducted and blood samples were collected for HIV, syphilis and Hepatitis C infection screening.Results17,377 (92.8%) of 18,730 migrant workers approached were interviewed. Among 17,377 participants, the HIV/AIDS knowledge rate was 66.2%. A total of 12,694 (73%) of the participants reported having ever had sexual intercourse, with 30.1% of single participants reporting having had sexual intercourse. Among those respondents with sexual experiences, 7.5% admitted they had two or more sexual partners and 4.9% reported having had sex with casual (unpaid) partners in the previous 12 months, whilst 3.7% had paid for sex. More than half of those who had paid for sex (59.4%) had not used a condom every time in their sexual acts with the sex workers. Multiple logistic regression analysis indicated that high risk sexual behavior (defined as sex with a casual or commercial sex partner without using a condom consistently) was associated with being divorced or widowed (P<0.05 for single); male gender; shorter duration of stay in Zhejiang; working in factory, market or domestic service (P<0.05 for odd job); having a province of origin inside Zhejiang; and drug use. The prevalence of HIV and HCV infections were 0.02% (95% CI: 0.01%–0.06%) and 0.40% (95%CI: 0.31%–0.51%), respectively. The prevalence of syphilis among those who were sexually active was 0.55% (95% CI: 0.43%–0.70%). Risk factors for syphilis included shorter duration of stay in Zhejiang, ethnic minority status, being divorced or widowed and having had multiple sex partners.ConclusionsMuch greater efforts are needed to promote safer sex, and programs for the control of syphilis need to be tailored for migrant workers in China.