Chemical composition,N-nitrosamine inhibition and antioxidant and antimicrobial properties of essential oil from Coreopsis tinctoria flowering tops

Coreopsis tinctoria flowering (CTF) tops from the Kunlun Mountains in Xinjing (north-western China) have been used for tea production for about a century. This study was to assess antioxidant, nitrite-scavenging and N-nitrosamine inhibitory and antimicrobial activities of the essential oil extracted from CTF tops. The essential oil was extracted through hydrodistillation and its chemical compositions were analysed by GC–MS. Seventy compounds of the oil were identified, representing 81.87% of total oil. The antioxidant capacities of the oil with IC₅₀ values for scavenging DPPH and ABTS were 287.66 ± 12.60 and 1.251 ± 0.127 μg mL^? 1, respectively. The nitrite-scavenging and N-nitrosamine inhibitory activities (IC₅₀) were 0.3912 ± 0.0127 and 0.6564 ± 0.036 μg mL^? 1, respectively. The oil has a certain antimicrobial capacity, but its capacity was weaker than that of penicillinG (24 μg mL^? 1). The oil showed antioxidant and antimicrobial capacities and had a stronger nitrite-scavenging and N-nitrosamine inhibitory properties.     

Electrode materials and reaction mechanisms in solid oxide fuel cells: a brief review

This work is focused on the comparative analysis of electrochemical and transport properties in the major families of cathode and anode compositions for intermediate-temperature solid oxide fuel cells (SOFCs) and materials science-related factors affecting electrode performance. The first part presents a brief overview of the electrochemical and chemical reactions in SOFCs, specific rate-determining steps of the electrode processes, solid oxide electrolyte ceramics, and effects of partial oxygen ionic and electronic conductivities in the SOFC components. The aspects associated with materials compatibility, thermal expansion, stability, and electrocatalytic behavior are also briefly discussed. Primary attention is centered on the experimental data and approaches reported during the last 10–15 years, reflecting the main challenges in the field of materials development for the ceramic fuel cells.     

An alternative strategy based on ultra-high-performance supercritical fluid chromatography for full monosaccharide compositional analysis of polysaccharides in Schisandra chinensis fruits

Due to green and environment-friendly characteristics, ultra-high-performance supercritical fluid chromatography has been widely used in analytical fields in recent years, but until now few reports are available for monosaccharide compositional analysis of macromolecule polysaccharides. In this study, an ultra-high-performance supercritical fluid chromatography technology with an unusual binary modifier is used to determine the monosaccharide compositions of natural polysaccharides. Each carbohydrate herein is simultaneously labeled as 1-pheny-3-methyl-5-pyrazolone and acetyl-derivative via pre-column derivatizations aiming to increase UV absorption sensitivity and decrease water solubility. Ten common monosaccharides are fully separated and detected on ultra-high-performance supercritical fluid chromatography combined with a photo-diode array detector by systematic optimization of multiple relevant parameters, for example, column stationary phases, organic modifiers, additives, flow rates, and so on. Compared with carbon dioxide as a mobile phase, the addition of a binary modifier increases the resolution of analytes. Additionally, this method has the advantages of small consumption of organic solvent, safety, and being environmental-friendly. It has been successfully applied for full monosaccharide compositional analysis of heteropolysaccharides from Schisandra chinensis fruits. To sum up, a new alternative approach is provided for monosaccharide compositional analysis of natural polysaccharides.     

浅谈无负压供水设备在现代居住小区中的推广与应用

介绍了传统二次加压供水设备的弊端,阐述了无负压供水设备的工作原理,描述了无负压供水设备的分类及系统组成,指出了无负压供水设备的优点。     

Implications of micro-compositions of garnet and biotite from high-grade meta-pelites

Based on detailed studies on the compositional zoning of garnet and biotite in pelitic rocks from the Jingshan group of granulite facies in north Jiaodong, P-T pseudosections with isopleths of Fe/(Fe + Mg) in garnet and biotite were calculated in the KF-MASH system for two representative rocks of sillimanite-garnet-cordierite-biotite gneiss ( Vbi/ Vg>1 ) and sillimanite-garnet gneiss (Vbi/ Vg<0.2) using the software THERMOCALC and the internally consistent thermodynamic dataset. With a comparison of the calculated Fe/(Fe+ Mg) values in garnet and biotite in the peak P-T fields constrained by peak mineral assemblages with the measured ones, it is concluded that the coarse garnet crystals with diffusion zoning from high grade meta-pelites can preserve their peak compositions even when they have experienced a cooling event, and that biotite crystals surrounded by fetsic minerals in biotite-rich rocks with Vbi/Vg> 1 can nearly preserve their peak compositions, and biotites in garnet-rich rocks with Vbi/Vg<0. 2 cannot preserve their peak compositions due to the influence of grain-boundary fluid.     

Synthesis and monomer reactivity ratios of (vinylcyclohexane-co-N-vinyl-2-pyrrolidone) copolymer

A copolymer containing vinylcyclohexane (VCH) and N-vinyl-2-pyrrolidone (VP) at different compositions was synthesized and characterized. The monomer reactivity ratios (MRR) were estimated by using the classical Fineman-Ross and Kelen-Tüdõs linear fitting methods. These parameters were also estimated using a nonlinear computational fitting procedure, known as reactivity ratios error in variable model (RREVM). In this case, the values of MRR are r_VP=2.2 and r_VCH=0.0. Composition shifts and MRR values for (vinylcyclohexane-co-N-vinyl-2-pyrrolidone) copolymer (VCH-co-VP) are interpreted in terms of the relative comonomeric structures. A copolymer with zones containing VP blocks with isolated units of VCH between them is obtained. The presence or absence of the resonance stabilization effect is taken into account. The results are compared with those of similar related copolymeric systems.     

A decomposition theorem for planar harmonic mappings

A necessary and sufficient condition is found for a complex-valued harmonic function to be decomposable as an analytic function followed by a univalent harmonic mapping.

     

氨基酸约化分类对亚线粒体蛋白定位的预测

在Du和Li构建的首个亚线粒体定位数据库基础上,将线粒体蛋白依据亚线粒体位置细分为四大类进行预测.对基于氨基酸的亲疏水特征、物理化学特征和结构特征的蛋白质序列约化信息做出讨论.给出在单肽组分和六类亲疏水约化情形下的蛋白质序列最佳分割位点,结果不仅符合真实生物学现象而且范围更加精确,可为相关实验研究提供参考.提出了最佳组合参数,该参数是ω=0.10,λ=22时亲疏水残基指数值及平行相关形式的伪氨基酸组分结合全序列单肽组分,利用支持向量机算法进行预测,达到了较好的预测结果.利用本文提出的最佳组合参数对未知蛋白序列进行检验,结果显示有一定注释作用,特别是对于Inner membrane类和Matrix类的预测精度较高.     

无序与有序分拆的双射关系

近几年,正整数的无序分拆与有序分拆之间存在的恒等式成为分拆理论研究者的重点研究对象,文章在探讨正整数的无序分拆与有序分拆相关问题的基础上,利用组合双射关系获得了无序分拆与有序分拆之间具有代表性的几个恒等式,同时运用Frobenius-分拆分析得到有序分拆与Frobenius-分拆之间具有代表性的一些双射关系,从而使无序分拆与有序分拆之间存在的关系更具一般性.     

Synthesis and characterization of hybrid Ag-ZnO nanocomposite for the application of sensor selectivity

Facile, rapid, and environmentally benign hybrid Ag-ZnO nanocomposites were synthesized by two steps from green synthesis approach at room temperature. The absence of an impurity peak in X-ray diffraction (XRD) pattern confirmed the formation of polycrystalline nanocomposite material. An additional peak (111) of Ag was detected along with ZnO crystalline wurtzite structure. The surface area electron diffraction (SAED) pattern further confirmed the crystallinity of nanocomposites. The compositional analysis of hybrid Ag-ZnO was determined by EDS-mapping and confirmed the presence of Zn, O and Ag in the composite. The room-temperature photoluminescence (PL) spectra of hybrid Ag-ZnO depict a weak ultraviolet (UV) emission at 385 nm, and the strong visible emission at ∼600 nm, while increasing the Ag concentration in to ZnO matrix, the UV peak was completely disappeared and major visible peak was moved to ∼500 nm indicated to the best optimal detection peak for sensors. The fluorescence spectra were measured with respect to Ag concentrations of Ag-ZnO nanocomposite at room temperature to investigate the functionality and the selectivity of nanomaterials. This work opens a notable way to fabricate Ag-ZnO nanohybrids, and makes a significant contribution to the fluorescence based sensor applications.