黄蜀葵花总黄酮对海马神经元缺氧复氧损伤的保护作用

目的: 研究黄蜀葵花总黄酮（total flavones of abelmoschl manihot,TFA）对海马神经元缺氧复氧损伤的保护作用以及可能的内皮衍生超级化因子（endothelium-dependent hyperpolarizing factor,EDHF）相关机制。方法: 采用原代培养的海马神经元建立缺氧4 h/复氧24 h损伤模型,预先在细胞培养上清内加入大鼠脑基底环动脉（basilar artery,BA）环,分别给予乙酰胆碱（acetylcholine,Ach）联合一氧化氮（nitric oxide,NO）合酶抑制剂Nω-nitro-L-arginine-methyl-ester（L-NAME)和前列环素（prostacyclin,PGI2）抑制剂indomethacin（Indo）;TFA联合L-NAME和Indo预处理。检测缺氧/复氧损伤后海马神经元存活率、培养上清液中乳酸脱氢酶（lactate dehydrogenase,LDH）活力的变化;另外,用激光共聚焦法检测细胞内游离Ca²⁺浓度。结果: 与单独应用Ach或者TFA预处理比较,Ach或者TFA联合脑基底动脉环均能明显改善缺氧/复氧后海马神经元存活率的降低,培养上清中LDH活力降低。此外,TFA联合脑基底动脉环抑制海马神经元细胞内游离Ca²⁺的增高,L-NAME及Indo对此结果并无显著影响。结论: TFA对缺氧/复氧致海马神经元损伤有明显的保护作用,其机制可能与促进EDHF释放,抑制细胞内Ca²⁺超载有关。     

基于信号时频分析理论识别时变模态参数的实验

为研究温度对结构模态参数的影响设计了一套温度可控的实验设备。在这套实验设备提供的可控温度环境中采集悬臂梁结构的加速度响应信号,利用基于信号时频分析的模态参数辨识算法处理实验数据,得到其时变模态参数,包括固有频率和振型,以此研究温度对其模态参数的影响。分析结果显示了基于信号时频分析的模态参数辨识算法在处理非平稳信号以得到结构的时变模态参数上的应用前景,更重要的是实验数据的分析结果较好地反映了温度对结构模态参数的影响,为热环境下结构振动特性分析提供了可靠而且有价值的分析方法和实验依据。     

用 EEGLAB 分析脑电信号磁

EEGLAB 是一种基于 Matlab 的工具箱。它主要用于处理连续记录的脑电信号（EEG）脑磁信号（MEG）和其它电生理数据。它运用的方法主要有独立分量分析（ICA ）、时间-频率分析[1]、绘制 ERP 图、排除伪迹和几种有用的可视化模式（对于求平均和单次提取数据）等。 EEGLAB 还为从事神经信号处理方法研究的开发人员提供了一个可扩展的开源的平台,他们利用邮件列表和世界各地的研究人员一起讨论新方法,研究出更多的 EEGLAB 的新插件。 EEGLAB 的插件可以通过下载设置后,直接融入并出现在用户菜单。 EEGLAB 可用于研究各种脑电信号,这些研究有助于对人类情绪探知和生理病理情况下的脑机制做研究,有助于了解人脑的工作原理,找到更有效的治疗精神疾病的方法。     

Antioxidant capacity and the relationship with polyphenol and Vitamin C in Actinidia fruits

Fruit of eight Actinidia genotypes were evaluated for antioxidant potential by several assays (DPPH, ABTS, ORAC, FRAP, SASR and MCC) and tested for their polyphenol composition and vitamin C contents. The significance analysis demonstrated that the antioxidant capacity of Actinidia eriantha and Actinidia latifolia fruits were significantly higher than that of other genotypes, which was about 3.3–8.7-fold higher than the Actinidia deliciosa cv. Hayward assayed in ABTS, DPPH, ORAC and FRAP methods. The total polyphenols and vitamin C contents showed a great variety amongst Actinidia genotypes and highly correlation with the total antioxidant capacity. It is concluded that significant genotypic difference exists in the total antioxidant capacity of Actinidia fruits. The wild A. eriantha and A. latifolia species have significantly higher antioxidant capacity than the cultivars of A. chinensis and A. deliciosa. Both total polyphenols and vitamin C are major contributors to the total antioxidant capacity in Actinidia fruit.     

Value-Added Esterification for the Recovery of Trifluoroacetic Acid: Batch Kinetics and Reactive Distillation Studies

The present work explores the recovery of trifluroacetic acid (TFA) by reactive distillation (RD) from dilute aqueous solutions. For this purpose, the reaction of TFA with methanol was chosen. Batch kinetic runs were initially conducted and low conversions were achieved. To improve upon this, RD runs were conducted in both batch mode and continuous mode. RD experiments showed notable recovery of the acid. Regression of batch kinetic data was also performed to obtain parameters that can be useful for further design.     

Characteristics of lipid composition differences between cultured and wild ayu (Plecoglossus altivelis)

The lipid levels and fatty acid compositions of the muscle and liver of ayu (sweetfish), Plecoglossus altivelis, and those of its stomach contents were investigated to clarify the difference in the lipid characteristics between aquacultured and wild samples. The lipid levels of the cultured P. altivelis (2.0-3.7%) were significantly higher than were those of the wild ones (1.1-1.4%). Triacylglycerols were the dominant depot lipids of both the cultured and wild samples, while phospholipids were the major components in the polar lipids. The major fatty acids in the muscle and liver triacylglycerols were 14:0, 16:0, 16:1n-7, 18:1n-9, 18:2n-6 (linoleic acid for cultured), 18:3n-3 (linolenic acid for wild), 20:5n-3 (icosapentaenoic acid), and 22:6n-3 (docosahexaenoic acid for cultured). In spite of similar levels of many fatty acids for cultured and wild triacylglycerols, the cultured samples had markedly higher levels of 18:1n-9, 18:2n-6, and 22:6n-3 while the wild ones had significantly higher levels of 18:3n-3 and 20:5n-3, which originate from their dietary lipids. The ratio (R_LA/LN) of linoleic acid (18:2n-6) to linolenic acid (18:3n-3) in the cultured samples was markedly higher than were those of the wild samples, and we can easily determine whether P. altivelis is cultured or wild by fatty acid analysis. Moreover, a significant difference in the long-chain PUFA levels, between the cultured and wild samples, was found: higher 22:6n-3 levels were found in the cultured samples while higher 20:5n-3 and 22:5n-3 levels were observed in the wild ones. This finding suggests a limitation of desaturation enzymes in P. altivelis and high 22:6n-3 levels in artificial feedstuff lipids.     

Genotypic dependent effect of exogenous glutathione on Cd-induced changes in proteins, ultrastructure and antioxidant defense enzymes in rice seedlings

Greenhouse hydroponic experiments were conducted using Cd-sensitive (cv. Xiushui63) and tolerant (Bing97252) rice genotypes to evaluate how different genotypes responded to Cd toxicity in presence of glutathione (GSH). Results showed that GSH alleviates Cd-toxicity, ameliorates Cd-induced damages on leaf/root ultrastructures. Nine proteins in roots were identified, using 2-DE coupled with mass spectrometry, whose expression were down-regulated in Xiushui63, up-regulated/unchanged in Bing97252 by Cd; coinstantaneously enhanced/unchanged in Cd + GSH over Cd alone treatment in both genotypes. They are l-ascorbate peroxidase, putative short-chain dehydrogenase/reductase, Glycolipid transfer protein, elongation factor, Os04g0652700, carbonic anhydrase, Os08g0374000, chitinase, and putative disease resistance response protein. Eight proteins in leaves with expression of increase in Bing97252 but down-regulate/unchange in Xiushui63, categorized as four groups of their functions: carbon metabolism, TCA cycle, photorespiration and RNA processing. Furthermore, we identified eight proteins with repressed expression in Cd-treated and up-regulated in Cd + GSH-treated rice leaves of Xiushui63.     

食品中的反式脂肪酸

反式脂肪酸是一种具有反式构型的不饱和脂肪酸,现代研究表明,它对心血管疾病、糖尿病及胎儿生长发育等会产生不利影响。本文从反式脂肪酸的结构、性质、食物来源及如何降低TFA等方面进行综述。     

On the interdependence between kinetics of friction-released thermal energy and the transition in wear mechanisms during sliding of metallic pairs

Sliding of complying solids is often associated with the release of thermal energy. This energy accumulates within the mechanically affected zone (MAZ) of the rubbing pair. The accumulation of thermal energy within the MAZ tends to maximize the potential energy at the interface. Now, since a maximized potential energy renders the sliding system unstable, one (or both) materials will respond in a manner that consumes (dissipates) part or all of the accumulated energy in order to re-establish system stability or at least equilibrium. The material response may be in many forms: oxidation, crack initiation, wear debris generation, transition in wear mechanism, etc. As such, one may consider that these processes are intrinsic responses by the material to dissipate energy. Moreover, many of these responses are triggered at different stages of rubbing according to the balance between the rate of external thermal energy release (which is a factor of the nominal operation parameters) and the rate of thermal energy accumulation—RTEA (which is mainly a function of thermal transport properties of the rubbing pair). An interesting feature of this view is that the later quantity—RTEA—is directly related to the ability of the particular solid to dissipate thermal loads. This quantity, which is termed here as the heat dissipation capacity (HDC), is directly related to the state of blockage of energy dissipation paths within the rubbing solid. The objective of this paper is therefore to study the relation between the change in the HDC of a sliding solid and the transition in the mechanism of wear. It is shown that there exists an inverse correlation between the change in the HDC and the transition in the mechanism of wear. Moreover, it is also shown that a so-called ratio of residual heat (RRH, representing the ratio between the actual thermal load and the part of that load that is not dissipated by the solid) is a significant parameter that influences the magnitude and mechanism of wear. The findings are applied to explain the wear behavior of two tribo systems: a titanium (Ti-6Al-4V) sliding on itself and sliding on a steel (AISI M2) counterpart.