Loss of Sirt6 in adipocytes impairs the ability of adipose tissue to adapt to intermittent fasting

Intermittent fasting (IF) is gaining popularity for its effectiveness in improving overall health, including its effectiveness in achieving weight loss and euglycemia. The molecular mechanisms of IF, however, are not well understood. This study investigated the relationship between adipocyte sirtuin 6 (Sirt6) and the metabolic benefits of IF. Adipocyte-specific Sirt6-knockout (aS6KO) mice and wild-type littermates were fed a high-fat diet (HFD) ad libitum for four weeks and then subjected to 12 weeks on a 2:1 IF regimen consisting of two days of feeding followed by one day of fasting. Compared with wild-type mice, aS6KO mice subjected to HFD + IF exhibited a diminished response, as reflected by their glucose and insulin intolerance, reduced energy expenditure and adipose tissue browning, and increased inflammation of white adipose tissue. Sirt6 deficiency in hepatocytes or in myeloid cells did not impair adaptation to IF. Finally, the results indicated that the impaired adipose tissue browning and reduced expression of UCP1 in aS6KO mice were accompanied by downregulation of p38 MAPK/ATF2 signaling. Our findings indicate that Sirt6 in adipocytes is critical to obtaining the improved glucose metabolism and metabolic profiles conferred by IF and that maintaining high levels of Sirt6 in adipocytes may mimic the health benefits of IF.Subject terms: Obesity, Fat metabolism     

MicroRNA-26a/b-5p promotes myocardial infarction-induced cell death by downregulating cytochrome c oxidase 5a

Myocardial infarction (MI) damage induces various types of cell death, and persistent ischemia causes cardiac contractile decline. An effective therapeutic strategy is needed to reduce myocardial cell death and induce cardiac recovery. Therefore, studies on molecular and genetic biomarkers of MI, such as microRNAs (miRs), have recently been increasing and attracting attention due to the ideal characteristics of miRs. The aim of the present study was to discover novel causative factors of MI using multiomics-based functional experiments. Through proteomic, MALDI-TOF-MS, RNA sequencing, and network analyses of myocardial infarcted rat hearts and in vitro functional analyses of myocardial cells, we found that cytochrome c oxidase subunit 5a (Cox5a) expression is noticeably decreased in myocardial infarcted rat hearts and myocardial cells under hypoxic conditions, regulates other identified proteins and is closely related to hypoxia-induced cell death. Moreover, using in silico and in vitro analyses, we found that miR-26a-5p and miR-26b-5p (miR-26a/b-5p) may directly modulate Cox5a, which regulates hypoxia-related cell death. The results of this study elucidate the direct molecular mechanisms linking miR-26a/b-5p and Cox5a in cell death induced by oxygen tension, which may contribute to the identification of new therapeutic targets to modulate cardiac function under physiological and pathological conditions.Subject terms: Protein-protein interaction networks, Predictive markers     

2-D激光多普勒振动测试仪的研究

本文阐述了一种2-D多普勒振动测试仪的基本测试原理和方法,分析了影响测量精度的要素,并就信号处理电路进行了设计.该仪器能同时非接触地测量振动体两个方向振动的频率和幅度,测量范围大、精度高.     

拍摄白光再现全息图的一种方法

本文给出了一种拍摄白光再现全息图装置 ,所拍的全息图在阳光或白炽灯照明下清晰地再现被拍的物体形象     

甘氨酸在葡萄糖-水和蔗糖-水混合溶剂中的体积性质

利用精密数字密度计测定了甘氨酸与不同组成葡萄糖-水、蔗糖、水混合溶剂 构成的三元系溶液的密度,计算了甘氨酸的表观摩尔体积、极限偏摩尔体积和理论 水化数,根据结构水合作用模型讨论了迁移偏摩尔体积的变化规律,并与乙二醇- 水和丙三醇-水等多羟基体系作了比较。结果表明,甘氨酸分子在多羟基化合物-水 体系中增体积效应的大小与多羟基化合物所含OH基数的多少有关。     

中空纤维液相微萃取-高效液相色谱法测定水中残留的氨基甲酸酯类农药

应用中空纤维液相微萃取(HP-LPME)技术建立了水样中呋喃丹、西维因、异丙威和乙霉威的高效液相色谱分析方法。对影响HP-LPME的实验条件进行了优化。采用Accurel Q3/2聚丙烯中空纤维,以甲苯为萃取溶剂,于室温、搅拌速度为720 r/min条件下在4.5 mL样品溶液中萃取20 min,萃取物在室温下经氮气流吹干后用流动相溶解进样。采用Baseline C18分离柱(4.6 mm×250 mm,5.0 μm),以甲醇-水(体积比为60∶40) 为流动相,流速为1.0 mL/min。呋喃丹、西维因、异丙威和乙霉威的检测波长分别为200,223,200和208 nm。该方法对4种氨基甲酸酯类农药的富集倍数均大于45倍;4种氨基甲酸酯类农药在10~100 μg/L质量浓度范围内,其质量浓度与峰面积之间有良好的线性关系,相关系数均大于0.99;呋喃丹、西维因、异丙威和乙霉威的检出限(S/N=3)分别为5,1,5和3 μg/L;实际水样中的加标回收率为82.0%~102.2%,相对标准偏差为2.0%～6.2%(n=6)。     

Tip gap height effects on flow structure and heat/mass transfer over plane tip of a high-turning turbine rotor blade

The effects of tip gap height-to-chord ratio, h/c, on the flow structure and heat/mass transfer over the plane tip surface of a large-scale high-turning turbine rotor blade have been investigated for h/c = 1.0%, 2.0%, 3.0% and 4.0%. For near-wall tip gap flow visualizations, a high-resolution oil film method is employed, and the naphthalene sublimation technique is used for local heat/mass transfer rate measurements. From the tip surface visualizations, a pair of vortices named “tip gap vortices” is identified in the leading edge region within the tip gap. The overall tip gap flow is characterized not only by the tip gap vortices but also by the flow separation/re-attachment process along the pressure-side tip edge. Within the separation bubble, there exist complicated near-wall flows moving toward a mid-chord flow converging area. With increasing h/c, the tip gap vortices, the flow separation/re-attachment, and the converging flows within the separation bubble tend to be intensified. In general, higher thermal load is found along the loci of the tip gap vortices and along the re-attachment line, while lower thermal load is observed behind the tip gap vortex system and near the mid-chord flow converging area. Heat/mass transfer characteristics with the variation of h/c are discussed in detail in conjunction with the tip gap flow features. Based on the flow visualizations and heat/mass transfer data, new realistic tip gap flow models have been proposed for h/c = 1.0 and 4.0%.     

Maximum spreading of electrically charged droplets impacting on dielectric substrates

In this work, the electric charging effect on the spreading of droplet impacting on dielectric substrates has been investigated. The charged water droplets were directed on the paraffin wax and the Teflon-coated plates. The impinging behavior was visualized and recorded using a CCD camera to identify the maximum extent of the flattened droplets. Droplet diameter and velocity approaching the wall were measured as well. The diameter of the electrically charged droplet at the maximum spread turned out to be larger compared to that of neutral droplet (at the maximum spread), and the difference becomes larger with increasing of the electric charge ratio (defined as the ratio of the actual electric charge to the Rayleigh limit). This phenomenon is considered to be due to reduction of effective interfacial tensions between the liquid and the gas and between the liquid and the solid by electric charging. Finally, an improved model was proposed to predict the maximum spreading ratio for electrically charged droplets by introducing correlations on the liquid–gas and the liquid–solid interfacial tensions.     

Effect of gamma window setting on activity measurement of 134Cs by 4πβ(LS)-γ coincidence method

Journal of Radioanalytical and Nuclear Chemistry - The sheared granite of El Sela represents one of the most promising uranium mineralization in the southern part of the eastern desert, in Egypt....     

Elastic and durable multi-cation-crosslinked anion exchange membrane based on poly(styrene-b-(ethylene-co-butylene)-b-styrene)

Anion exchange membranes (AEMs), as the core component of the new generation anion exchange membrane fuel cells (AEMFCs), directly determine the performance and the lifetime of this energy conversion device. Here, AEMs with pendant multiple quaternary ammonium anchored onto the poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) backbone are synthesized. The comb-shaped copolymer SEBS-C16 is synthesized with N,N-dimethyl-1-hexadecylamine and chloromethylated SEBS to improve solubility, then the multi-cation crosslinker is prepared and grafted on the above backbone to fabricate a series of flexible multi-cation crosslinked SEBS-based AEMs (SEBS-C16-xC4, where x% is the ratio of the crosslinker to polystyrene block) with practical properties. The obtained SEBS-C16-20C4 membrane exhibits a microphase separated morphology with an interdomain spacing of 18.87 nm. Benefited from the ion channels, SEBS-C16-20C4 shows high conductivity of 77.78 mS/cm at 80°C. Additionally, the prepared SEBS-C16-20C4 membrane with ion exchange capacity of 2.35 mmol/g also exhibits enhanced alkaline stability (5.87% hydroxide conductivity decrease in 2 M NaOH solution at 80°C after 1,700 hr) and improved mechanical properties, compared with the non-crosslinked SEBS-C16 sample. Furthermore, AEMFC single cell performance is evaluated with the SEBS-C16-20C4 membrane, and a maximum power density of 182 mW/cm² is achieved at 80°C under H₂/O₂ conditions.