Integrated metabolomics analysis of the effect of PPARδ agonist GW501516 on catabolism of BCAAs and carboxylic acids in diabetic mice

The peroxisome proliferator-activated receptor(PPARδ) agonists are reported to improve insulin sensitivity,reduce glucose levels,and alleviate dysfunctional lipid metabolism in animal models of type 2 diabetes mellitus.However,the underlying mechanisms remain incompletely understood.Metabolism plays an essential role in the biological system.Monitoring of metabolic changes in response to disease conditions or drug treatment is critical for better understanding of the pathophysiological mechanisms.In this study,metabolic profiling analysis by gas chromatography-mass spectrometry integrated with targeted analysis by liquid chro matography-mass spectrometry was carried out in plasma samples of db/db diabetic mice after six-week treatment of PPARδ agonist GW501516.GW501516 treatment significantly altered levels of metabolites,such as branched-chain amino acids(BCAAs),BCAA metabolites(3-hydroxyisobutyric acid and 3-hydroxyisovaleric acid),long-chain fatty acids,uric acid and ketone bodies(3-hydroxybutyric acid and 2-hydroxybutyric acid) which are all associated with the impaired systemic insulin sensitivity.The pre sent results indicate the beneficial effect of PPARδ agonist in alleviating insulin resistance of diabetic mice by favorably modulating metabolic profile,thus providing valuable information in understanding the therapeutic potential of PPARδ agonists in correcting metabolic dysfunction in diabetes.     

Evidence of the synergetic role of charged species and atomic oxygen in the molecular etching of PTFE surfaces for hydrophobic surface synthesis

The transformation of a poly(tetrafluoroethylene) (PTFE) hydrophobic surface into a superhydrophobic one using a low pressure RF plasma is explored using optical emission spectrometry (OES), X-ray photoelectron spectroscopy (XPS), water contact angle (WCA) measurements, mass measurements, and atomic force microscopy (AFM). It is shown that the increase in contact angle is due to an increase of roughness provoked by a chemical etching of the surface. We propose a molecular mechanism for etching that requires the simultaneous presence of atomic oxygen and negatively charged species (electrons) at the PTFE surface.     

塑料中金属氧化物的XRF分析

本文描述塑料中A1、Ti、Mg和Fe的氧化物的一种测定方法。以石蜡代替塑料制备校准标准,塑料样品直接压片侧量其金属氧化物含量,方法准确、快速,满足生产要求。     

毛细电色谱法分离七种苯取代物

用毛细电色谱法成功地分离了七种苯取代物,并获得了很好的重现性和分离度。     

风源热泵空调器除霜技术实验研究

风源热泵空调器的结霜问题和除霜控制技术受到制冷与空调领域学者的广泛关注。文中重点对普遍采用时间温度法除霜控制技术的家用空调器制热运行时 ,结霜和除霜过程进行了深入地实验研究。结果表明 ,在较宽的气候变化范围 ,该控制方法工作不可靠 ,容易出现除霜不净和过早除霜的现象。提出了能适应气候变化的模糊自修正除霜技术的设计思想。     

侧面抽运板状激光介质的热汇冷却

高热负荷固体激光介质的热效应已经成为制约激光器功率进一步提高的严重障碍,只有对激光介质进行有效的冷却才能保证其安全运行。以不均匀换热系数模型为基础,研究了具有非均匀内热源的侧面双向抽运板状激光介质在狭窄通道强制对流冷却情况下的耦合换热问题,对热汇冷却方案下介质的温度分布和热应力分布进行了数值模拟和分析,并对复合介质、蓝宝石和金刚石三种热汇材料进行对比。结果表明,忽视换热系数的非均匀性将导致应力计算结果偏低。对于侧面抽运、侧面冷却的激光介质,金刚石热汇冷却方案最佳,蓝宝石热汇方案次之,而复合介质方案不宜采用。     

Synthesis of Cu^Ⅱ/ZIF-8 Metal-organic Framework Catalyst and Its Application in the Aerobic Oxidation of Alcohols

The tliree-dimensional copper-doped zeolitic imidazolate framework ZIF-8(Cu^Ⅱ/ZIF-8) was prepared by a metal ion exchange process, using reaction of three different copper salts, zinc nitrate hexahydrate[Zn(NO)3·6H2O] and 2?methylimidazole(2-MelM) under nitrogen atmosphere at the room temperature. The TEM and PXRD results indicated that the morphology of Cu^Ⅱ/ZIF-8 was rhombic dodecahedron and the structure was intact after copper was doped into the porous ZIF-8. The synthesized Cu(NO3)2/ZIF-8 heterogeneous catalyst showed an excellent activity for tlie aerobic oxidation of primary alcohols employing molecular oxygen as oxidant. Moreover, tlie Cu(NO3)2/ZIF-8 heterogeneous catalyst can cycled 15 times without leaching of copper.     

Transformation of nitrogen during hydrothermal carbonization of sewage sludge: Effects of temperature and Na/Ca acetates addition

This study reports the effects of temperature and Ca/Na acetates addition on the transformation of nitrogen during hydrothermal carbonization of sewage sludge at 160–250 °C. The nitrogen species in the hydrochar, aqueous, oil and gas products from sludge hydrothermal carbonization at different temperatures are well characterized, with a focus on the amino acid species in various products. Temperature is found to greatly affect the nitrogen transformation during sludge hydrothermal carbonization. At 160 °C, 47.3% of nitrogen is transformed into the aqueous product. When the temperature increases to 250 °C, only 27.1% of nitrogen is retained in the hydrochar, while 69.2 and 6.7% of nitrogen is present in the aqueous and oil products, respectively. During hydrothermal carbonization, the protein-N is first converted into the polypeptide-N in the aqueous product, followed by its further decomposition into the NH+ 4-N. This leads to a high content of the NH+ 4-N in the aqueous product, especially at increased temperatures. The labile protein-N is also transformed into the heterocylic-N (especially the pyrrole-N) in the hydrochar as the temperature increases. Among all nitrogen species in the aqueous product, the polypeptide-N consisting of amino acids with the alkyl group is the most stable. Moreover, the addition of NaAc and CaAc₂ reduces the nitrogen retention in the hydrochar, mainly due to enhanced hydrolysis of the protein-N. While for CaAc₂ addition, the deamination of the polypeptide-N is also enhanced, leading to a higher NH+ 4-N in the aqueous product. Our results show that the type of amino acid in protein is important to determine the nitrogen transformation pathways, and acetate addition is an important strategy for enhancing nitrogen removal in the hydrochar during hydrothermal carbonization.     

超氧化物歧化酶在L-半胱氨酸修饰金电极上电化学行为的现场拉曼光谱研究

在以电化学方法确认L半胱氨酸对铜锌超氧化物歧化酶(copper,zincsuperoxidedismutase,SOD)在金丝电极上的电子迁移过程起促进作用的基础上,本文论述了将拉曼光谱电化学方法应用于猪红细胞SOD在经L半胱氨酸修饰的金丝电极上的电化学行为的现场拉曼光谱研究。研究结果从分子水平上提供了有关L半胱氨酸修饰在金电极上的电化学过程中,以及SOD在L半胱氨酸修饰的金电极上发生电子迁移过程中,存在于SOD、L半胱氨酸与金电极之间的相互成键作用情况随电化学过程进行而发生变化的微观结构信息,并进行了必要的分析和探讨。