86 research outputs found
Motion of Cesium Atoms in the One-Dimensional Magneto-Optical Trap
The force to which Cs atoms are subjected in the one-dimensional magneto-optical trap (lD-MOT) is calculated, and properties of this force are discussed. Several methods to increase the number of Cs atoms in the lD-MOT are presented on the basis of the analysis of the capture and escape of Cs atoms in the ID-MOT
Network Analysis of RAD51 Proteins in Metazoa and the Evolutionary Relationships With Their Archaeal Homologs
The RAD51 (DNA repair protein RAD51) recombinases are essential for homologous recombination, DNA repair, and genome stability. Overexpression of RAD51 proteins has been observed in many cancer cells, such as thyroid carcinoma, breast cancer, pancreatic cancer, and others. In Metazoa, there are multiple members of RAD51 (RAD51, RAD51B, RAD51C, RAD51D, DMC1) (DNA meiotic recombinase 1), XRCC2 (X-ray repair cross-complementing 2), and XRCC3. In this study, we used a protein sequence similarity network (SSN) to analyze the evolutionary relationship within this protein family. The SSN based on the RAD51 proteins from Metazoa indicated that there are several proteins that have yet to be functionally defined. The SSN based on the distribution of the proteins supports the hypothesis that horizontal gene transfer plays an important role in the evolution of RAD51 proteins. Multiple sequence alignments with structural information revealed that the amino acid residues for ATP and Mg2+ are highly conserved. The seven RAD51 proteins in humans are under different selective pressure: RAD51 and DMC1 are under stringent negative selection, while other proteins are subject to relatively relaxed negative selection. Furthermore, the expression levels of the seven genes in different tissues showed that the genes in the same cluster in the phylogenetic tree showed similar expression profiles. Finally, the SSN based on the RAD51 proteins from both eukaryotes and prokaryotes suggested that the eukaryotic RAD51 recombinases share a common ancestor with the archaeal homologs, but XRCC2 may have a different origin. These findings expand the understanding of the evolution and diversity of RAD51 recombinases in Metazoa
Subhealth: definition, criteria for diagnosis and potential prevalence in the central region of China
BACKGROUND: A full evaluation of health conditions is necessary for the effective implementation of public health interventions. However, terms to address the intermediate state between health and disease are lacking, leading the public to overlook this state and thus increasing the risks of developing disease. METHODS: A cross-sectional health survey of 1,473 randomly recruited Chinese Han adults of both sexes living in the central region of China. The criteria for diagnosis of subhealth was defined as the presence of ≥ 1 of the following abnormalities: body mass index ≥ 25 kg/m(2) or waist circumference ≥ 102 cm in men and 88 cm in women; systolic pressure 120–139 mmHg and/or diastolic pressure 80–89 mmHg; serum triglyceride level ≥ 150 mg/dL and/or total cholesterol level ≥ 200 mg/dL and/or high-density lipoprotein cholesterol level < 40 mg/dL in men and 50 mg/dL in women; serum glucose level 110–125 mg/dL; estimated glomerular filtration rate 60–89 ml/min/1.73 m(2); levels of liver enzymes in liver function tests between 41–59 U/L, or with fatty liver disease but < 33% of affected hepatocytes; levels of oxidative stress biomarkers beyond the reference range of 95%; or problems with both sleep quality and psychological state. RESULTS: The prevalences of subhealth and disease in the central region of China were 36.6% and 43.1%, respectively. The prevalence of disease increased from 26.3% in participants aged 20–39 years, to 47.6% and 78.9% for participants aged 40–59 years and those aged 60 years or older, respectively. Compared with participants aged 20–39, the prevalences of health and subhealth in participants aged 60 years or older decreased by 86.7% and 60.3%, respectively. The prevalence of subhealth was increased in association with increases in lifestyle risk scores, while the prevalences of both health and disease were reduced. CONCLUSION: The prevalences of subhealth and disease are high in central China. Subhealth is associated with high lifestyle risk scores. Both the health care sector and the public should pay more attention to subhealth. Lifestyle modifications and/or psychological interventions are needed to ameliorate these conditions
The transcription factor Ste12-like increases the mycelial abiotic stress tolerance and regulates the fruiting body development of Flammulina filiformis
IntroductionFlammulina filiformis is one of the most commercially important edible fungi worldwide, with its nutritional value and medicinal properties. It becomes a good model species to study the tolerance of abiotic stress during mycelia growth in edible mushroom cultivation. Transcription factor Ste12 has been reported to be involved in the regulation of stress tolerance and sexual reproduction in fungi.MethodsIn this study, identification and phylogenetic analysis of ste12-like was performed by bioinformatics methods. Four ste12-like overexpression transformants of F. filiformis were constructed by Agrobacterium tumefaciens-mediated transformation.Results and DiscussionPhylogenetic analysis showed that Ste12-like contained conserved amino acid sequences. All the overexpression transformants were more tolerant to salt stress, cold stress and oxidative stress than wild-type strains. In the fruiting experiment, the number of fruiting bodies of overexpression transformants increased compared with wild-type strains, but the growth rate of stipes slowed down. It suggested that gene ste12-like was involved in the regulation of abiotic stress tolerance and fruiting body development in F. filiformis
Sensitive Bioanalysis Based on in-Situ Droplet Anodic Stripping Voltammetric Detection of CdS Quantum Dots Label after Enhanced Cathodic Preconcentration
We report a protocol of CdS-labeled sandwich-type amperometric bioanalysis with high sensitivity, on the basis of simultaneous chemical-dissolution/cathodic-enrichment of the CdS quantum dot biolabel and anodic stripping voltammetry (ASV) detection of Cd directly on the bioelectrode. We added a microliter droplet of 0.1 M aqueous HNO3 to dissolve CdS on the bioelectrode and simultaneously achieved the potentiostatic cathodic preconcentration of Cd by starting the potentiostatic operation before HNO3 addition, which can largely increase the ASV signal. Our protocol was used for immunoanalysis and aptamer-based bioanalysis of several proteins, giving limits of detection of 4.5 fg·mL−1 for human immunoglobulin G, 3.0 fg·mL−1 for human carcinoembryonic antigen (CEA), 4.9 fg·mL−1 for human α-fetoprotein (AFP), and 0.9 fM for thrombin, which are better than many reported results. The simultaneous and sensitive analysis of CEA and AFP at two screen-printed carbon electrodes was also conducted by our protocol
A Mechanistic Study of Asymmetric Transfer Hydrogenation of Imines on a Chiral Phosphoric Acid Derived Indium Metal-Organic Framework
A density functional theory (DFT) study is reported to examine the asymmetric transfer hydrogenation (ATH) of imines catalyzed by an indium metal-organic framework (In-MOF) derived from a chiral phosphoric acid (CPA). It is revealed that the imine and reducing agent (i.e., thiazoline) are simultaneously adsorbed on the CPA through H-bonding to form an intermediate, subsequently, a proton is transferred from thiazoline to imine. The transition state TS-R and TS-S are stabilized on the CPA via H-bonding. Compared to the TS-S, the TS-R has shorter H-bonding distances and longer C-H···π distances, it is more stable and experiences less steric hindrance. Consequently, the TS-R exhibits a lower activation barrier affording to the (R)-enantiomer within 68.1% ee in toluene. Imines with substituted groups such as −NO2, −F, and −OCH3 are used to investigate the substitution effects on the ATH. In the presence of an electron-withdrawing group like −NO2, the electrophilicity of imine is enhanced and the activation barrier is decreased. The non-covalent interactions and activation-strain model (ASM) analysis reveal that the structural distortions and the differential noncovalent interactions of TSs in a rigid In-MOF provide the inherent driving force for enantioselectivity. For −OCH3 substituted imine, the TS-S has the strongest steric hindrance, leading to the highest enantioselectivity. When the solvent is changed from toluene to dichloromethane, acetonitrile, and dimethylsulfoxide with increasing polarity, the activation energies of transition state increase whereas their difference decreases. This implies the reaction is slowed down and the enantioselectivity becomes lower in a solvent of smaller polarity. Among the four solvents, toluene turns out to be the best for the ATH. The calculated results in this study are in fairly good agreement with experimental observations. This study provides a mechanistic understanding of the reaction mechanism, as well as substitution and solvent effects on the activity and enantioselectivity of the ATH. The microscopic insights are useful for the development of new chiral MOFs toward important asymmetric reactions
Conversion of Waste Oil from Oil Refinery into Emulsion Liquid Membrane for Removal of Phenol: Stability Evaluation, Modeling and Optimization
The waste oil emulsion liquid membrane produced by waste oil from oil refineries (WELM) is used to separate the phenol in purified water from the sour water stripper in oil refinery facilities, and the stability of WELM was studied. It is verified that waste refinery oil can be produced into emulsion liquid membrane with good stability and high removal rate for the first time. The WELM stability models were established by response surface methodology (RSM) and artificial neural network (ANN), respectively. The principle and mechanism of various parameters, as well as the interaction effects on the stability of WELM, are proposed. The effects of parameters, including the ratio of Span-80, liquid paraffin, the ratio of internal and oil, and the rotational speed of the homogenizer, were investigated. Under the optimal operating parameters, the WELM had a demulsification percentage of just 0.481%, and the prediction results of RSM and ANN were 0.536% and 0.545%, respectively. Both models demonstrate good predictability. The WELM stability model has a high application value in the treatment of phenol-containing wastewater in the oil refining industry, and provides a green method of resource recovery
Multiscale Single Image Dehazing Based on Adaptive Wavelet Fusion
Removing the haze effects on images or videos is a challenging and meaningful task for image processing and computer vision applications. In this paper, we propose a multiscale fusion method to remove the haze from a single image. Based on the existing dark channel prior and optics theory, two atmospheric veils with different scales are first derived from the hazy image. Then, a novel and adaptive local similarity-based wavelet fusion method is proposed for preserving the significant scene depth property and avoiding blocky artifacts. Finally, the clear haze-free image is restored by solving the atmospheric scattering model. Experimental results demonstrate that the proposed method can yield comparative or even better results than several state-of-the-art methods by subjective and objective evaluations
The Morphologies of the Semiconductor Oxides and Their Gas-Sensing Properties
Semiconductor oxide chemoresistive gas sensors are widely used for detecting deleterious gases due to low cost, simple preparation, rapid response and high sensitivity. The performance of gas sensor is greatly affected by the morphology of the semiconductor oxide. There are many semiconductor oxide morphologies, including zero-dimensional, one-dimensional, two-dimensional and three-dimensional ones. The semiconductor oxides with different morphologies significantly enhance the gas-sensing performance. Among the various morphologies, hollow nanostructures and core-shell nanostructures are always the focus of research in the field of gas sensors due to their distinctive structural characteristics and superior performance. Herein the morphologies of semiconductor oxides and their gas-sensing properties are reviewed. This review also proposes a potential strategy for the enhancement of gas-sensing performance in the future
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