The mechanics of fracture of human hair

Premature fracture and splitting of human head hair is cosmetically undesirable and at worse, unsightly. It is often regarded both by the hair's owner and by others as indicative of hair in poor condition and attracts considerable expenditure on hair toiletry products in sometimes vague attempts to prevent or repair the damage. This paper defines the mechanical events which underlie the fracture of hairs as they occur on the head and insofar as they satisfy the different fracture morphologies seen under the scanning electron microscope. Factors affecting propensity for fracture are considered. A significant conclusion is that hair 'strength', as might be assessed by the consumer, has little to do with the tensile mechanical properties of the fibres but that bending and associated longitudinal shear processes are of much greater relevance.     

Supramolecular structure of the casein micelle

The supramolecular structure of colloidal casein micelles in milk was investigated by using a sample preparation protocol based on adsorption of proteins onto a poly-l-lysine and parlodion-coated copper grid, staining of proteins and calcium phosphate by uranyl oxalate, instantaneous freezing, and drying under a high vacuum. High-resolution transmission electron microscopy stereo-images were obtained showing the interior structure of casein micelles. On the basis of our interpretation of these images, an interlocked lattice model was developed in which both casein-calcium phosphate aggregates and casein polymer chains act together to maintain casein micelle integrity. The caseins form linear and branched chains (2 to 5 proteins long) interlocked by the casein-stabilized calcium phosphate nanoclusters. This model suggests that stabilization of calcium phosphate nanoclusters by phosphoserine domains of α_s1-, α_s2-, or β-casein, or their combination, would orient their hydrophobic domains outward, allowing interaction and binding to other casein molecules. Other interactions between the caseins, such as calcium bridging, could also occur and further stabilize the supramolecule. The combination of having an interlocked lattice structure and multiple interactions results in an open, sponge-like colloidal supramolecule that is resistant to spatial changes and disintegration. Hydrophobic interactions between caseins surrounding a calcium phosphate nanocluster would prevent complete dissociation of casein micelles when the calcium phosphate nanoclusters are solubilized. Likewise, calcium bridging and other electrostatic interactions between caseins would prevent dissociation of the casein micelles into casein-calcium phosphate nanocluster aggregates when milk is cooled or urea is added to milk, and hydrophobic interactions are reduced. The appearance of both polymer chains and small aggregate particles during milk synthesis would also be expected based on this interlocked lattice model of casein micelles, and its supramolecule structure thus exhibits the principles of self-aggregation, interdependence, and diversity observed in nature.     

纤网型缝编非织造材料结构性能初探

纤网型缝编技术采用织针勾取纤网中的纤维束形成线圈并编织,从而将纤网加固成纤网型缝编非织造材料,可作为室内装饰和产业用织物。通过实验研究了纤网型缝编非织造材料的纤网结构、拉伸性能、顶破强度等,并与针织物、针刺非织造材料进行了对比,探讨了影响纤网型缝编非织造材料基本性能的因素。     

亚麻脱胶后纤维的纵向结构和强力的研究

采用新的方法对亚麻进行浸渍，并探讨了浸渍后的亚麻的纵向结构和强力，从扫描电镜中发现纤维有支化现象．分析了亚麻在加工的不同阶段中强力产生差异的原因。     

苏丹红TiO2光催化降解活性与分子电子结构相关性研究

以TiO2为光催化剂,对Ⅰ、Ⅱ、Ⅲ、Ⅳ号苏丹红进行光催化降解实验,并采用量子化学方法密度泛函理论B3LYP／6-31G＊＊计算苏丹红的分子电子结构,研究苏丹红TiO2光催化降解活性与分子电子结构的相关性。结果表明,苏丹红的光催化降解活性与分子电子结构存在密切的相关性,按照苏丹红Ⅰ、Ⅱ、Ⅲ、Ⅳ的顺序,偶极矩增大、最高占有轨道能量升高、电子光谱激发能降低、HOMO-LUMO能隙减小、C-N或N=N键的键级减小,光催化降解活性逐渐升高。     

类黄酮与酚酸等天然抗氧化剂的结构与其抗氧化力的关系

近几十年来,葡萄（酒）、茶叶等植物中天然抗氧化剂所具有的保健功能已引起了人们的高度重视,国内外许多科学家对这些抗氧化剂的结构、功能及制取方法等方面进行了不懈的研究。本文在前人研究基础上 试验,对类黄酮类和酚酸类等两类天然抗氧化剂的结构与其抗氧化力的关系进行了综述,阐述了二者的关系,不同结构的抗氧化剂在不同的作用环境中（液相与脂相）表现出的抗氧化力差别很大。     

Carrageenan Effects on Salt-Soluble Meat Proteins in Model Systems

The effects of κ-, ι-, and λ-carrageenans (CGNs) on the rheological properties, water loss, and ultrastructure of salt-soluble meat protein (SSMP) gels were evaluated. κ-CGN increased gel strength and water retention of SSMP, suggesting that a molecular interaction may have occurred. However, no indications of specific molecular interactions were observed upon addition of stabilizing/destabilizing reagents. Electron microscopy indicated that improvement of water retention and texture of SSMP/κ-CGN gels may be due to physical rearrangement of the κ-CGN and SSMP molecules.     

大直径滤用聚合物单丝的热处理

将大直径聚丙烯(PP)、聚己内酰胺(PA6)、聚对苯二甲酸乙二醇酯(PET)、聚苯硫醚(PPS)单丝进行热处理,测试纤维的拉伸强度及勾结强度.数据表明:PP纤维的强损温度为120～130℃,PA6纤维的强损温度在150℃左右,PET纤维的强损温度为160～170℃,而PPS纤维的强损温度为220～230℃.因此PPS单...     

Fixation Staining Methods for Examining Microstructure in Whipped Cream by Electron Microscopy

Whipped dairy cream (WDC) specimens were prepared for examination by transmission electron mircoscopy (TEM) and scanning electron microscopy (SEM) by one of three alternative post-mordant procedures, i.e., imidazole-buffered osmium tetroxide (IBO), ferri-cyanide osmium tetroxide and tricomplex osmium tetroxide. These procedures utilized a tannic acid-guanidine-HCI mordant, thiocarboh-ydrazide as a bridging Iigand, and a p-phenylenediamine en bloc stain treatment to improve specimen fixation and staining. TEM and SEM specjmens prepared by all three procedures provided good contrast and resolution of the microstructure of WDC. The IBO method provided more uniform staining and more complete fixation and retention of lipids in milkfat globules than either of the other two methods.     

电子显微镜在龟裂树脂乳液聚合技术中的应用

本文利用透射电镜分析了影响龟裂树脂乳液粒子结构的几个主要因素,探讨了乳液粒子结构与其性能及应用效果的应用,同时,对国内外龟裂树脂乳液粒子结构进行了比较。     

小麦脱皮前后结构特性的分析

小麦分角质和粉质，其结构的软硬程度也有所不同。在小麦脱皮制粉中，脱皮率的高低直接影响小麦的硬度，利用硬度指数测定不同脱皮率的小麦，脱皮率越高硬度就越小。了解脱皮过程中小麦硬度的变化，可为制粉中磨辊技术参数的确定提供依据。     

The effects of particle size, connective tissue and cooking regime upon properties of washed mechanically recovered broiler meat

Mechanically recovered meat (MRM) from broilers was washed with water, with or without prior chopping and with or without sieving to remove connective tissue. The resultant protein extract was mixed with salt and cooked in a one-step (directly to 80°C) or two-step (to 55°C and then to 80°C) cooking regime, to form gels. Washing broiler MRM gave stronger gels with lower cooking loss and expressible moisture than unwashed broiler MRM. These washed gels were also lighter in colour and less red. The best products were produced when some of the collagen had been removed by sieving, but not if the samples had Wrst been chopped, even though the total protein and dry matter contents were also reduced. A two-step cooking procedure enhanced gel strength. Evidence of a more porous, but dense, structure of washed broiler MRM subjected to a two-step cooking treatment was given by scanning electron microscopy and these differences could be related to the changes in gel strength and water holding.     

纤维形态特性对纸张结构和性能的影响

纤维特征在造纸过程中影响纸张的结构,决定纸张的性能。本文主要论述了造纸纤维的几种重要特征,如纤维长度、粗度,纤维强度等,分析了纤维的特征对纸张结构和性能的影响。     

涂层工艺对PVC膜结构复合材料力学性能的影响

采用涂层法制备高经密机织物增强体PVC膜结构柔性复合材料,以实验为基础分析了涂层前后拉伸性能变化的原因,同时研究了涂层工艺(焙烘温度、涂层厚度、增塑剂份数)对PVC膜材的力学性能的影响。结果表明:涂层厚度对力学性能的影响最明显,增加增塑剂份数可导致膜材的力学性能下降;综合考虑各涂层因素对膜材力学性能的影响,选择焙烘温度160℃、涂层厚度0.685 mm、增塑剂份数50份时,可获得力学性能较佳的膜结构复合材料。     

影响喷气纺纱线强力的因素

主要从喷气纺成纱条件、成纱过程、成纱结构等方面分析了影响喷气纱强力的因素。     

改性大豆蛋白二级结构变化对其粘接强度的影响

采用不同浓度的尿素（1、3、5、8mol／L）对大豆分离蛋白进行改性,使其二级结构发生变化。测定了大豆蛋白α-螺旋、β-折叠、β-转角和无规则卷曲含量,并对二级结构含量与尿素改性大豆蛋白对木材粘接强度的关系进行了研究。结果表明,SPI对木材的粘接特性影响是十分复杂的,并不能简单地用蛋白质二级结构的含量多少来表示,同时改性SPI的抗水性也很难用其二级结构的含量来解释。因此,关于改性大豆蛋白对木材的粘接性能及其抗水性机理需要深入研究。     

基于无连接件快速拆装结构的泡桐家具节点强度研究

在传统家具结构的基础上,对泡桐家具箱式结构的稳定性、强度、零部件间结合力进行测试,通过对比分析证实无胶燕尾榫快速可拆装结构满足家具基本使用性要求。     

基于无连接件快速拆装结构的泡桐家具节点强度研究

在传统家具结构的基础上,对泡桐家具箱式结构的稳定性、强度、零部件间结合力进行测试,通过对比分析证实无胶燕尾榫快速可拆装结构满足家具基本使用性要求。     

Effect of polyphenolic ingredients on physical characteristics of cheese

A novel cheese product developed based on the incorporation of various polyphenolic compounds was evaluated for its texture characteristics. Single phenolic compounds including catechin, epigallocatechin gallate (EGCG), tannic acid, homovanillic acid, hesperetin and flavone, along with natural crude compounds such as grape extract, green tea extract and dehydrated cranberry powder, were added as functional ingredients during the cheese-making process. Cheese curds containing polyphenolic compounds at a concentration of 0.5 mg/mL showed a decrease of curd moisture content (CMC) while the gel strength (GS) was not affected. Structural differences were observed when crude polyphenolic compounds were added to the cheese, resulting in rough and granular structures. Physical properties of the cheese product were evaluated after adding bioactive phenolic compounds to the cheese curd. We fully expect to apply this approach to other dairy products in the future.     

甲壳素纤维结构与性能研究

对甲壳素纤维的结构性能进行了测定分析。研究表明:甲壳素纤维的纵向有沟槽,有些纤维的芯层存在空隙。甲壳素纤维的干、湿态强力比毛纤维高,干态强力基本与粘胶纤维相近。甲壳素纤维的湿强明显低于干强,但下降的幅度要低于普通粘胶。甲壳素纤维的表面比较光滑,卷曲性能较差,抱合力较差,在纺丝时需严格控制湿度。总体看目前的甲壳素纤维还需要进一步提高品质,以满足高品质甲壳素纤维类纺织产品的开发生产。