Surface mediated ligands addressing bottleneck of room-temperature synthesized inorganic perovskite nanocrystals toward efficient light-emitting diodes

Cesium lead halide perovskites (CsPbX3) have become superior candidates for perspective optoelectronic applications. However, room temperature synthesized CsPbX3 nanocrystals (NCs) suffer from serious lattice/surface traps, mostly induced by nonequilibrium reactions and polar solvent systems. Thus, direct assembly of such poor crystals cannot be available toward high efficiency light emitting diodes (LEDs). To address this issue, differing from the general post-treatment works, here we propose a double-terminal diamine bromide salt to in situ passivate the surface traps of room temperature synthesized CsPbBr3 NCs. High-quality NC solutions with photoluminescence quantum yield (PLQY) beyond 90% are obtained owing to the renovated surface bromide vacancies. Meanwhile, instead of longer oleylamine (OLA) ligand, the abridged diamine bromine ligand could significantly enhance charge transport throughout the NC film. In addition, the NC based LED performance is found related to chain length of the ligand, where the optimal luminance of 14021 Cd m(-2) and current efficiency of 25.5 Cd A(-1) are achieved by 1, 4-butanediamine bromide passivated NC devices. This work provides a direct efficient approach to meet the device application of room temperature synthesized perovskite NCs, underlines the significance of selective ligands to address the challenges of NC emitters in future displays and solid-state lighting

Disparities and risks of sexually transmissible infections among men who have sex with men in China: a meta-analysis and data synthesis.

BACKGROUND: Sexually transmitted infections (STIs), including Hepatitis B and C virus, are emerging public health risks in China, especially among men who have sex with men (MSM). This study aims to assess the magnitude and risks of STIs among Chinese MSM. METHODS: Chinese and English peer-reviewed articles were searched in five electronic databases from January 2000 to February 2013. Pooled prevalence estimates for each STI infection were calculated using meta-analysis. Infection risks of STIs in MSM, HIV-positive MSM and male sex workers (MSW) were obtained. This review followed the PRISMA guidelines and was registered in PROSPERO. RESULTS: Eighty-eight articles (11 in English and 77 in Chinese) investigating 35,203 MSM in 28 provinces were included in this review. The prevalence levels of STIs among MSM were 6.3% (95% CI: 3.5-11.0%) for chlamydia, 1.5% (0.7-2.9%) for genital wart, 1.9% (1.3-2.7%) for gonorrhoea, 8.9% (7.8-10.2%) for hepatitis B (HBV), 1.2% (1.0-1.6%) for hepatitis C (HCV), 66.3% (57.4-74.1%) for human papillomavirus (HPV), 10.6% (6.2-17.6%) for herpes simplex virus (HSV-2) and 4.3% (3.2-5.8%) for Ureaplasma urealyticum. HIV-positive MSM have consistently higher odds of all these infections than the broader MSM population. As a subgroup of MSM, MSW were 2.5 (1.4-4.7), 5.7 (2.7-12.3), and 2.2 (1.4-3.7) times more likely to be infected with chlamydia, gonorrhoea and HCV than the broader MSM population, respectively. CONCLUSION: Prevalence levels of STIs among MSW were significantly higher than the broader MSM population. Co-infection of HIV and STIs were prevalent among Chinese MSM. Integration of HIV and STIs healthcare and surveillance systems is essential in providing effective HIV/STIs preventive measures and treatments. TRIAL REGISTRATION: PROSPERO NO: CRD42013003721

Common Molecular Etiologies Are Rare in Nonsyndromic Tibetan Chinese Patients with Hearing Impairment

Background: Thirty thousand infants are born every year with congenital hearing impairment in mainland China. Racial and regional factors are important in clinical diagnosis of genetic deafness. However, molecular etiology of hearing impairment in the Tibetan Chinese population living in the Tibetan Plateau has not been investigated. To provide appropriate genetic testing and counseling to Tibetan families, we investigated molecular etiology of nonsyndromic deafness in this population. Methods: A total of 114 unrelated deaf Tibetan children from the Tibet Autonomous Region were enrolled. Five prominent deafness-related genes, GJB2, SLC26A4, GJB6, POU3F4, and mtDNA 12S rRNA, were analyzed. Inner ear development was evaluated by temporal CT. A total of 106 Tibetan hearing normal individuals were included as genetic controls. For radiological comparison, 120 patients, mainly of Han ethnicity, with sensorineural hearing loss were analyzed by temporal CT. Results: None of the Tibetan patients carried diallelic GJB2 or SLC26A4 mutations. Two patients with a history of aminoglycoside usage carried homogeneous mtDNA 12S rRNA A1555G mutation. Two controls were homozygous for 12S rRNA A1555G. There were no mutations in GJB6 or POU3F4. A diagnosis of inner ear malformation was made in 20.18 % of the Tibetan patients and 21.67 % of the Han deaf group. Enlarged vestibular aqueduct, the most common inner ear deformity, was not found in theTibetan patients, but was seen in 18.33 % of the Han patients. Common molecular etiologies

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Mid-infrared Emission Properties of Ho3+-doped Ge-Ga-S-CsI Glasses

International audienceA serial of chalcogenide glasses based on Ge-Ga-S-CsI system doped with the different Ho3+ ions were synthesized by melt-quenching technique. The properties of glasses including refractive indexes, absorption spectra, mid-infrared emission spectra and lifetimes of 5I6 level of Ho3+ions were measured. The Judd-Ofelt intensity parameters Ωi (i=2,4,6), oscillator strength fcal, spontaneous transition probabilities Arad for Ho3+ion were calculated by Judd-Ofelt theory. Multiphonon relaxation rates of the Ho3+:5I5→5I6 and 5I6→5I7 in Ge-Ga-S-CsI glasses were evaluated. Effect of Ho3+ion concentration on the fluorescence spectra was investigated. The results indicate that the fluorescence under 900 nm excitation with peak wavelength at 2.81μm and 3.86μm are due to the Ho3+:5I5→5I6 and 5I6→5I7 transition, respectively. The intensity of the mid-infrared fluorescence are enhanced with the Ho3+ ion concentration increasing from 0.5wt% to 1.0wt%. Multiphonon relaxation rates are 29s-1 and 34s-1 for the Ho3+:5I5→5I6 and 5I6→5I7 transition, respectively

Effects of Temperature and Ytterbium Sensitizing on Upconversion Characteristics in Erbium-doped Tellurite Glasses

International audienceTellurite glasses 75TeO2-20ZnO-(4.6-x)La2O3-0.4Er2O3-xYb2O3 (x=0, 0.4, 0.8, 2.0, 3.2, 4.0) were prepared by conventional melt-quenching method. The effects of temperature (8-300K) and the ytterbium concentration on upconversion characteristics were investigated. When the Yb3+ concentration is 2mol%, the upconversion emission intensities around 545nm and 657nm present 6-fold and 4-fold enhancement, respectively, compared with Er3+-doped glass at room temperature. The green emission intensities around 530nm present monotonic increase with increasing temperature from 8K to 300K. The green emission intensities around 545nm increase with increasing temperature from 8K to 80K and reach the maximum at around 80K, then decrease with increasing temperature from 80K to 300K. The characteristics of the red emission intensity around 657nm are similar to the green emission intensity around 545nm. The effects of temperature and concentration of ytterbium on upconversion characteristics are analyzed by rate equations in details, which match well with the experiment results

Experimental and numerical investigation of mid-infrared laser in Pr3+-doped chalcogenide fiber

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The Effects of Deoxidants on Ge-Se-Te Chalcogenide Glasses

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Low temperature emission characteristics of an ytterbium sensitized erbium-doped tellurite glass

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