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

Light-induced degradation in p-type gallium co-doped solar grade multicrystalline silicon wafers and solar cells

National Natural Science Foundation of China [61076056]This letter focuses on the evolution under illumination of the minority carrier lifetime and conversion efficiency of p-type gallium (Ga) co-doped solar grade multicrystalline silicon wafers and solar cells. We present experimental data regarding the concentration of boron-oxygen (B-O) defects in this silicon when subjected to illumination, and the concentration was found to depend on [B]-[P] rather than [B] or the net doping p(0)([B] + [Ga] - [P]). This result implies that the compensated B is unable to form the B-O defect. Minority carrier lifetime and EQE measurements at different degradation states indicate that the B-O defect and Fe-acceptor pairs are the two key centers contributed to LID in this material

Luminescent properties of Sr2B2O5: Tm 3+, Na+ blue phosphor

A novel blue phosphor, Sr2B2O5: Tm 3+, Na+ for white light-emitting diodes (W-LEDs) was prepared by solid-state synthesis and its structure and luminescence properties were investigated. This phosphor can be effectively excited within the broad near ultraviolet (NUV) wavelength region, from 340 nm to 370 nm, and exhibits a satisfactory blue performance. The emission peaks are observed at 457 nm (blue) and 475 nm (blue), due to the respective transitions of 1D 2→3F4 and 1G 4→H6. Seven mole percent of doping concentration of Tm3+ was shown to be optimal. Concentration quenching occurs when Tm3+ concentration is beyond 7 mol%, its mechanism being explained by dipole-dipole interaction of Tm3+ and being confirmed by decay property measurements. We have made a deep analysis on the effect of charge compensation reagent on luminescence intensity. Good blue emissions with the CIE chromaticity coordinates (0.173, 0.165) could be achieved. Our results suggest that the Sr2B2O5: Tm3+, Na + phosphor is a potential blue-emitting material. ? 2013 Elsevier Ltd and Techna Group S.r.l.All rights reserved

Effect of temperature on crystalline silicon solar cells processed from chemical and metallurgical route

Effect of temperature on monocrystalline and multicrystalline silicon solar cells processed from chemical (EG-Si) and metallurgical (SoGM-Si) routes was investigated in the range of 280-350 K. The temperature coefficients of important parameters related with the cell property were discussed. Experimental results indicate that the T-coefficient of conversion efficiency (η) of multicrystalline EG-Si cell processed from chemical is only 68% that of the monocrystalline EG-Si cell. Furthermore, the η of both types of SoGM-Si cells decrease much less than that of the EG-Si cells with the increase in temperature. Additionally, the recombination fraction, the minority carrier lifetime, the carrier mobility decrease and the band-gap shrinkage were also investigated to reveal the intrinsic temperature dependence mechanism. In order to confirm the results, we used numerical simulation software AMPS-1D (analysis of microelectronic and photonic structure in one dimension program) to simulate the temperature dependence of solar cell performances. The results of numerical simulation were basically consistent with the experimental results. ? 2014 Elsevier GmbH

Natural mycotoxin contamination in dog food: A review on toxicity and detoxification methods

Nowadays, the companion animals (dogs or other pets) are considered as members of the family and have established strong emotional relationships with their owners. Dogs are long lived compared to food animals, so safety, adequacy, and efficacy of dog food is of great importance for their health. Cereals, cereal by-products as well as feedstuffs of plant origin are commonly employed food resources in dry food, yet are potential ingredients for mycotoxins contamination, so dogs are theoretically more vulnerable to exposure when consumed daily. Aflatoxins (AF), deoxynivalenol (DON), fumonisins (FUM), ochratoxin A (OTA), and zearalenone (ZEA) are the most frequent mycotoxins that might present in dog food and cause toxicity on the growth and metabolism of dogs. An understanding of toxicological effects and detoxification methods (physical, chemical, or biological approaches) of mycotoxins will help to improve commercial ped food quality, reduce harm and minimize exposure to dogs. Herein, we outline a description of mycotoxins detected in dog food, toxicity and clinical findings in dogs, as well as methods applied in mycotoxins detoxification. This review aims to provide a reference for future studies involved in the evaluation of the risk, preventative strategies, and clear criteria of mycotoxins for minimizing exposure, reducing harm, and preventing mycotoxicosis in dog

Global competence of medical students: An assessment scale and preliminary investigation in China

Introduction The importance of global competence has been acknowledged in medical care as well as medical education. This study aims to develop a scale assessing the global competence of medical students, determine the factor structure and internal consistency of the scale and explore the underlying factors influencing the global competence of Chinese medical students in 8-year programs. Methods A questionnaire (Global Competence Assessment Scale for Medical Students, MS-GCAS) was developed, and a cross-sectional multicenter survey was conducted in 1062 medical students from 10 medical schools in China. Questionnaire data were analyzed using exploratory factor analysis and multiple linear regression. Results The exploratory factor analysis revealed a three-factor scale. The MS-GCAS has good internal consistency (Cronbach’s alpha = 0.79 to 0.87). In the multivariate regression analyses, medical education stage (pDiscussion The MS-GCAS has the potential to serve as a tool to measure the global competence of medical students. This three-factor scale can be used by medical education researches to improve future versions. Medical schools should conduct further educational reforms to promote students’ global competence

Global competence of medical students: An assessment scale and preliminary investigation in China.

IntroductionThe importance of global competence has been acknowledged in medical care as well as medical education. This study aims to develop a scale assessing the global competence of medical students, determine the factor structure and internal consistency of the scale and explore the underlying factors influencing the global competence of Chinese medical students in 8-year programs.MethodsA questionnaire (Global Competence Assessment Scale for Medical Students, MS-GCAS) was developed, and a cross-sectional multicenter survey was conducted in 1062 medical students from 10 medical schools in China. Questionnaire data were analyzed using exploratory factor analysis and multiple linear regression.ResultsThe exploratory factor analysis revealed a three-factor scale. The MS-GCAS has good internal consistency (Cronbach's alpha = 0.79 to 0.87). In the multivariate regression analyses, medical education stage (pDiscussionThe MS-GCAS has the potential to serve as a tool to measure the global competence of medical students. This three-factor scale can be used by medical education researches to improve future versions. Medical schools should conduct further educational reforms to promote students' global competence

DataSheet1_Ginsenoside Rd protects transgenic Caenorhabditis elegans from β-amyloid toxicity by activating oxidative resistant.PDF

Alzheimer’s disease (AD) is a serious public health issue but few drugs are currently available for the disease, and these only target the symptoms. It is well established that oxidative stress plays a crucial role in AD, and there is compelling evidence linking oxidative stress to β-amyloid (Aβ). An exciting source of potential new AD therapeutic medication possibilities is medicinal plants. Ginsenoside Rd (GS-Rd) is one of the main bioactive substances in ginseng extracts. In our study, we used a network pharmacology analysis to identify overlapping GS-Rd (therapeutic) and AD (disease)-relevant protein targets, gene ontology (GO) and bio-process annotation, and the KEGG pathway analysis data predicted that GS-Rd impacts multiple targets and pathways, such as the MAPK signal pathway and the JAT-STAT3 signaling pathway. We then assessed the role of GS-Rd in C. elegans and found that GS-Rd prolongs lifespan, improves resistance to heat stress, delays physical paralysis and increases oxidative stress responses. Overall, these results suggest that GS-Rd protects against the toxicity of Aβ. The RNA-seq analysis revealed that GS-Rd achieves its effects by regulating gene expressions like daf-16 and skn-1, as well as by participating in many AD-related pathways like the MAPK signaling pathway. In addition, in CL4176 worms, GS-Rd decreased reactive oxygen species (ROS) levels and increased SOD activity. Additional research with transgenic worms showed that GS-Rd aided in the movement of DAF-16 from the cytoplasm to the nucleus. Taken together, the results indicate that GS-Rd significantly reduces Aβ aggregation by targeting the MAPK signal pathway, induces nuclear translocation of DAF-16 to activate downstream signaling pathways and increases resistance to oxidative stress in C. elegans to protect against Aβ-induced toxicity.</p