织物电磁屏蔽性能的评价方法

介绍了电磁屏蔽的研究历史,分析了电磁屏蔽原理以及电磁屏蔽性能的评价方法,指出电磁屏蔽织物屏蔽效能的测试方法包括W.D.Nason法、MILD-STD法及改进的MIL-STD-285法、同轴传输线路法、法兰同轴法、双盒法,对比了后4种测试方法的优缺点和基本参数。     

茶花浸提液及其功能性成分结合胆酸盐的效果探讨

在体外模拟人体消化环境,研究真空冷冻干燥、杀青干燥及不杀青干燥等处理茶花的浸提液及其功能性成分对各种胆酸盐的结合能力,同时探讨了茶多酚、茶多糖和咖啡碱与胆酸盐结合的相互影响。结果表明:杀青干燥处理茶花的浸提液对胆酸盐的吸附结合效果最好,茶多酚吸附结合胆酸盐的能力显著高于茶多糖和咖啡碱。三者吸附结合胆酸盐的能力与其质量浓度呈显著性相关关系。在浸提液中,三者并无增效作用,在浸提液中茶多酚是吸附胆酸盐的主要成分。     

基于电沉积石墨烯阪崎肠杆菌免疫传感器研究

为研制一种新型免疫传感器并用于快速检测阪崎肠杆菌(E.sakazakii),采用自组装方法将辣根过氧化物酶标记的阪崎肠杆菌抗体(HRP-anti-E.sakazakii)固定于修饰有电沉积石墨烯(ERGO)的丝网印刷碳电极上,制得一次性酶免疫传感器。采用循环伏安法(CV)考察不同修饰电极的电化学特性,根据CV还原峰电流值的变化对E.sakazakii进行快速检测。在优化的检测条件下,该方法检测E.sakazakii的线性范围为102～109cfu/mL,检测限为9.1×101cfu/mL(S/N=3)。该酶免疫传感器灵敏度高,并具有良好的特异性、重现性(RSD=6.4%)、稳定性(4℃无菌容器中放置15d后电流响应为初始值的90.05%),具有一定潜在应用价值。     

抗菌肽对热应激肉鸡血液学及血氧自由基的影响

了解猪小肠抗菌肽在热应激条件下对肉鸡血液学及血氧自由基的影响。方法 选用30只两周龄健康华都AA+肉鸡,称重后随机分为3组:常温对照组、单纯热应激组和抗菌肽+热应激组,每组10只,热应激10天。结果 抗菌肽+热应激组与单纯热应激组比较全血黏度、血浆黏度、红细胞压积明显降低(P＜0.01);抗菌肽+热应激组血清中总蛋白(TP)、球蛋白(GLO)、葡萄糖(GLU)及谷丙转氨酶(ALT)、谷草转氨酶(AST)、碱性磷酸酶(ALP)与单纯热应激组比较均升高;总胆固醇(TC)、甘油三酯(TG)、尿素(UREA)、低密度脂蛋白(LDL)、高密度脂蛋白(HDL)与单纯热应激组比较明显降低;抗菌肽+热应激组SOD、GSH-Px活性与单纯热应激组比较明显升高(P＜0.01);MDA含量与单纯热应激组比较差异有统计学意义(P＜0.01)。结论 热应激条件下口服抗菌肽可以调节肉鸡血液成份及流变状态、增强体液免疫、平衡氧自由基、降低氧化应激反应,使机体有效抵抗热应激。     

Co‐inoculation of yeast and lactic acid bacteria to improve cherry wines sensory quality

This study examined the effect of co‐inoculation of yeast and lactic acid bacteria (LAB) on the chemical and sensory characteristics of cherry wines, in comparison with a traditional sequential culture. Three LABs were investigated, including two O. oeni (SG26 and Viniflora) and one L. plantarum (PL18). All co‐inoculations significantly shortened the fermentation time (average 8 days earlier) to reach a stable level of residual sugar (<2 g L^?1) and L‐malic acid (<0.5 g L^?1), and no inhibitory effect on the yeast proliferation was observed. For volatiles determined, co‐culture with SG26 produced the greatest amount of volatile components (138.5 mg L^?1), whereas sequential inoculation with PL18 had the lowest level (119.6 mg L^?1). PCA result revealed that different LABs had diverse influences on the volatile profile of cherry wines, and sensory analysis confirmed that these samples presented distinct sensory profiles, and particularly, a stronger note of fruity was perceived when co‐culture was used.     

Effect of microwave curing on antimicrobial activity of chitosan biguanidine hydrochloride treated wool fabrics

An alternative microwave curing system was used for curing chitosan biguanidine hydrochloride treated wool fabric to study its effects on the antimicrobial activity of the fabric. The effects of microwave curing at different irradiation power and treatment time on the physical properties of wool fabrics and the adsorption rate of chitosan biguanidine hydrochloride on wool fabrics has been examined. Comparisons were made between conventionally cured wool fabric and microwave‐cured wool fabric treated with chitosan biguanidine hydrochloride. The influence of microwave curing on the efficiency of crosslinking was studied by using scanning electron microscopy and Fourier transform infrared spectroscopy. Microwave‐cured samples showed a higher degree of crosslinking than conventionally cured samples without high losses in strength properties. Antimicrobial properties and the durability of the finish after repeated laundering results also supported the higher degree of crosslinking that occurred in microwave curing.     

Influences of moisture absorption and chemical treatments on the resin flow characteristics of natural fibre nonwoven mats

A major challenge for the use of natural fibres in polymeric composites is their incompatibility with commonly used matrices, causing weak interfaces of the final composites. Many surface treatments to natural fibres have been proposed to eliminate or reduce these problems. In this paper, we evaluate the influences of three commonly used natural fibre chemical treatments on the resin flow characteristics of flax fibre nonwoven mats in a vacuum-assisted resin transfer moulding process. The alkalization treatment significantly increases the in-plane permeability and flow anisotropy of the natural nonwoven mat due to changes in fibre diameter, fibre surface tension and mat structure. The effects of silane and acetylation treatments on resin flow are much smaller. It is well known that in comparison with glass fibre, natural fibres can absorb a large amount of moisture from surrounding air. The absorption of moisture causes a considerable reduction in the in-plane permeability of natural fibre nonwoven mats.     

Antioxidant polyketide phenolic metabolites from the edible mushroom Cortinarius purpurascens

Phytochemical investigation of the ethyl acetate extract of the edible macrofungus, Cortinarius purpurascens, led to the isolation of nine anthraquinone-related pigments, citreorosein 6,8-dimethyl ether (1), physcione (2), rufoolivacin (3), rufoolivacin C (4), rufoolivacin D (5), leucorufoolivacin (6), verbindung cr11 (7), verbindung cr60 (8) and 1-Hydroxy-3-methyl-2-isopropanyl-6,8-dimethoxyanthraquinone (9). The structures of these isolated compounds were characterised by spectroscopic methods and comparison with published data. Among the tested compounds, 3–6 exhibited potent DPPH radical-scavenging activity with IC₅₀ values in the range of 3–8 μg/ml. The results indicated that the fungus is a possible source of natural products with potential antioxidant activity.     

Dynamic changes of the content of biogenic amines in Chinese rice wine during the brewing process

This study examined the biogenic amine content of the brewing raw material (wheat Qu, seed starter, mash or liquid) during fermentation and during the maturation and storage process. Pre‐column derivatization and high‐performance liquid chromatography were employed to analyse the dynamic changes in biogenic amines during the Chinese rice wine brewing process. Some aliphatic amines (putrescine, cadaverine, spermine) were already found to be present in the glutinous rice and wheat Qu, but the content was below 2.88 mg/kg. None of the amines were detected in the brewing water. The biogenic amine content in the seed starter exhibited a large variation range (16.43–87.72 mg/L), which could influence the total content of biogenic amines prior to fermentation. A much more obvious increase in biogenic amines stemmed from the fermentation process, with the presence of a biogenic amine‐producing bacteria and precursor amino amines. In the first 2 days, the biogenic amine content increased sharply, followed by a slow increase over the next 4 days, and the content reached a maximum value on day 6; subsequently there was a decrease or fluctuation in the concentration. After clarification and cooking, the biogenic amine content increased significantly; however, a slight decrease was observed during storage, especially for putrescine and histamine. Putrescine and tyramine were the most prevalent amines in all of the samples. Overall, the content of biogenic amines was found to be within the safe level for human health, ranging from 54.52 to 146. 35 mg/L. Copyright © 2013 The Institute of Brewing & Distilling     

海藻酸钠在面团体系中的应用研究进展

海藻酸钠又叫褐藻胶,是从海带等褐藻植物中提取的天然高分子多糖,是人体不可缺少的一种营养素———水溶性膳食纤维,具有良好的食用安全性及生物相容性,对预防结肠癌、心血管疾病以及铅、铬等重金属在体内的积累具有很好的辅助疗效作用。海藻酸钠由于其特殊的理化性质和功能特性广泛应用于食品、医药、纺织等产品中,作为增稠剂、乳化剂、胶凝剂、持水剂、稳定剂等使用,已成为使用最广泛的食品添加剂之一,受到国内外学者的广泛关注。本文主要介绍了海藻酸钠的分子结构及理化功能特性,并对近几年海藻酸钠在面团体系(如流变学特性、糊化特性和微观结构)及其在面包、馒头等相关产品中的应用研究进展进行综述,为海藻酸钠在以后相关研究中提供参考。