Interference prevention in size-exclusion chromatographic analysis of debranched starch glucans by aqueous system

Branch chain-length distribution of amylopectin plays an important role on the characteristics of starch. One of the adapted protocols for determining the chain-length distribution and mass proportion of starch molecules is that starch is debranched with isoamylase and then analyzed by using high-performance size-exclusion chromatography coupled with multiangle laser-light scattering and refractive index detection (HPSEC-MALS-RI). However, ammonium sulfate in commercial isoamylase and acetate in debranching buffer give significant interferences on the chromatograms because of their undesirable ionic interactions with column sorbent materials. This study deals with development for correcting those interferences. A weak anion-exchange resin or selective precipitation with barium acetate was employed to remove sulfate prior to HPSEC determination. The interference of acetate was overcome by means of high ionic strength eluent, 0.3 M sodium nitrate. The specific refractive index increment (dn/dc) of amylodextrin was determined to be 0.147 using the modified conditions and was applied to calculate the molecular weight distribution of debranched starch molecules.     

Spatial Calculation Methods of Three Main Trusses Continuous Plate truss Composite Bridge

According to the structural features of three main trusses continuous plate truss composite bridge, two composite beam methods are presented by constructing the displacement mode of composite beam elements and deriving the stiffness matrix of composite beam elements. The characteristic of composite beam method one is that the bridge slab is taken as the top flange of the chord of main truss and combined with the chord of main truss to form a steel concrete composite beam; the characteristic of composite beam method two is that the bridge slab is taken as the top flange of longitudinal and traverse beam and form a steel concrete composite beam with longitudinal and traverse beams. And as for the conventional plate beam composite method, the slab is characterized by forming bridge slab system with continuous isotropic sheets and longitudinal and traverse beams to bear load. Also, the comparison between theoretical results and experimental ones verifies the effectiveness of the above three methods.     

柑橘愈伤组织内源激素代谢与体细胞胚胎发生能力关系的研究Ⅰ.柑橘不同愈伤组织体细胞胚胎发生能力的比较

为了探明柑橘愈伤组织内源激素代谢与体细胞胚胎发生能力的关系，研究了长期继代保存的纽荷尔脐橙和伏令夏橙不同愈伤组织的体细胞胚胎发生.结果表明，无论是在加有3%蔗糖的MT增殖培养基上，还是在加有30 mL/L甘油的MT分化培养基上，纽荷尔脐橙的胚性愈伤组织和二倍体伏令夏橙愈伤组织的体细胞胚胎发生能力均较强，而纽荷尔脐橙的非胚性愈伤组织，四倍体和六倍体伏令夏橙愈伤组织的体细胞胚胎发生能力较弱.     

Ankaflavin and monascin regulate endothelial adhesion molecules and endothelial NO synthase (eNOS) expression induced by tumor necrosis factor-α (TNF-α) in human umbilical vein endothelial cells (HUVECs)

Previous studies have established that red mold rice can regulate blood pressure in spontaneously hypertensive rats (SHR) and that Monascus -fermented products, including monacolin K, ankaflavin (AF), and monascin (MS), can inhibit expression of adhesion factors such as E-selectin and endothelin-1 to prevent human acute monocytic leukemia cell line THP-1 monocytes from adhering to human aortic endothelial cells. However, it remains unknown whether AF and MS act directly on human umbilical endothelial cells (HUVECs) to enhance nitric oxide (NO) synthesis through the stimulation of endothelial NO synthase (eNOS) expression. To address this knowledge gap, this study investigated whether AF and MS directly regulate NO synthesis and attenuate adhesion factor expression induced by treatment with tumor necrosis factor-α (TNF-α) in HUVECs. The results revealed that both AF and MS (20 μM) treatments promoted increases in eNOS expression and decreases in vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and endothelin-1 mRNA and protein expression resulting from 12 h of TNF-α treatment. These effects are attributed to the ability of AF and MS to inhibit extracellular signal-regulated protein kinase (ERK) phosphorylation and nuclear factor κB (NF-κB) translocation from the cytoplasm into the nucleus, thereby exerting antihypertensive activity.     

Proteomic study on usnic-acid-induced hepatotoxicity in rats

Usnic acid, a lichen metabolite, is used as a dietary supplement for weight loss. However, clinical studies have shown that usnic acid causes hepatotoxicity. The present study aims to investigate the mechanism of usnic acid hepatotoxicity in vivo. Two-dimensional gel electrophoresis coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was used to analyze the expression profiles of differentially regulated and expressed proteins in rat liver after usnic acid administration. The results reveal the differential expression of 10 proteins in usnic-acid-treated rats compared to the normal controls. These proteins are associated with oxidative stress, lipid metabolism, and several other molecular pathways. The endoplasmic reticulum and mitochondria may be the primary targets of usnic-acid-induced hepatotoxicity.     

Characterization of Polymethoxylated Flavonoids (PMFs) in the Peels of 'Shatangju' Mandarin ( Citrus reticulata Blanco) by Online High-Performance Liquid Chromatography Coupled to Photodiode Array Detection and Electrospray Tandem Mass Spectrometry

A sensitive HPLC-DAD-ESI-MS/MS method was established to screen and identify the polymethoxylated flavonoids (PMFs) in the peels of 'Shatangju' mandarin ( Citrus reticulata Blanco). Eight PMF standards, including four polymethoxylated flavones, two polymethoxylated flavanones, and two polymethoxylated chalcones, were first to be analyzed in positive mode by CID-MS/MS. On the basis of the ESI-MS(n) characteristics of PMFs and the results of EIC-MS/MS experiment, 32 PMFs including 24 flavones and 8 flavanones or chalcones were screened from the complex extract of the peels of 'Shatangju' mandarin. Among them, 10 PMFs were hydroxylated polymethoxyflavonoids (OH-PMFs), and the rest were all permethoxylated PMFs. This was the first systematic report of the presence of PMFs in the peels of 'Shatangju' mandarin, especially for polymethoxylated flavanones and chalcones. Meanwhile, the contents of the three main PMFs and total flavonoids in the peels of 'Shatangju' were determined by HPLC and UV spectrophotometry, respectively. The results indicated that the developed analytical method could be employed as an effective technique for the characterization of PMFs.     

Design, synthesis, and particular biological behaviors of chain-opening nitromethylene neonicotinoids with cis configuration

On the basis of the structure of heterocyclic-fused cis configuration derivatives and chain-opening neonicotinoids, two series of novel chain-opening tetrahydropyridine analogues were designed and synthesized. The preliminary bioassay tests were determined on cowpea aphid (Aphis craccivora) and armyworm (Pseudaletia separata Walker). The results showed that some of the target compounds exhibited repellent effects, whereas others showed good insecticidal activities.     

广东外塘甲鱼养殖模式利弊分析

由于广东独特优越的自然气候条件,甲鱼养殖量较大,每年放养量在一亿只左右,主要养殖集中在顺德、中山、东莞、惠州一带。近年来,随着养殖规模的不断扩大,甲鱼的发病率有逐年上升之势,综合其原因较为复杂,其中有环境污染恶化的直接影响,另外也与养殖中的某些不科     

油茶开发的对策

油茶是我市主要的食用油料树种，资源丰富，分布很广，栽培历史悠久，在国民经济和人民生活中占有重要的地位。市委、市政府把发展油茶生产作为新的经济增长点，给予高度重视，已初见成效。但是，目前总体水平还很低，发展极不平衡，离目标要求还有较大的差距。不少油茶林...