39—THE FLOW OF LIQUID FROM A JET THROUGH A COMPRESSIBLE POROUS LAYER. PART III: THE CHARACTERISTICS OF LIQUID FLOW THROUGH A COMPRESSIBLE LAYER OF LOOSE WOOL

The effects on the conditions of flow of the surface and configurational properties of the fibres in a compressible porous layer are discussed. The characteristics of a layer of wool are evaluated, and its compressibility is determined. It is shown that, when a liquid of initial uniform pressure flows through a compressible porous medium, the pressure gradient within the medium increases with the distance of flow. The resulting pressure drop is found to depend on a function of the ratio of the downstream to the upstream porosity of the compressible medium. Experimental results are reported for permeable flow through various layers of loose wool; these indicate that, when the flow is disturbed turbulent, the pressure drop through the layers is proportional to the square of the filter velocity. This result is not readily apparent from the graphs of pressure drop against filter velocity because of the compressibility of the fibres.     

Water–disaccharides interactions in saturated solution and the crystallisation conditions

This paper reports solubility data and measurements of viscosity of the saturated aqueous solutions of sucrose, maltitol, and trehalose. Likewise, the metastable zone width and velocity of nucleation of the three disaccharides are compared. The narrowest metastable zone is observed for maltitol and the largest for trehalose. Such behaviour is due to a higher affinity of trehalose for water. Moreover, the crystallisation of anhydrous disaccharides in aqueous solution necessitates that hydration water be removed and evacuated from crystal integration surface to the bulk of solution to allow the growth of crystals. This step of disassociation and diffusion of hydration water proves to be the controlling step of the crystallisation process. Structural features at the origin of the differences between the three sugars are studied by FTIR spectroscopy. Modifications of frequencies and intensities of the vibrations around the glycosidic bond are interpreted in terms of conformational flexibility. Arguments like H-bond strength or conformational flexibility of the two monomers around the glycosidic oxygen were evoked as possible explanations of the behaviour of disaccharides. Likewise stability of hydration of the disaccharides is derived from the interpretation of FTIR spectra. These structural features help in interpreting the differences in crystallisation conditions and to hypothesize about the cryoprotective ability of the studied molecules.     

21—THE ACETYLATION OF COTTON

An account is given of a study of the effect of the amount of activating agent, the temperature, the catalyst, and the diluents used in the acetylation of cotton with perchloric acid as catalyst. Sulphuric acid was compared with perchloric acid as a catalyst. The effects of traces of water, the amount of acetyl chloride, and the rate of acetylation were studied in the acetylation of cotton with acetyl chloride and pyridine. The conditions in all cases were such that the acetylated cotton retained its fibrous form.     

基于下肢运动特征的纬编无缝瑜伽裤结构设计

为提升瑜伽裤的功能性和舒适性,研究了纬编无缝瑜伽裤结构设计的方法。首先分析人体下肢围度特征及瑜伽运动中体表皮肤形变,选用氨纶和锦纶编织7种不同组织结构的面料,测量面料的拉伸性能和压力值。最后从围度尺寸和纵向结构进行纬编无缝瑜伽裤分区结构设计,并进行应用举例。结果表明,服装围度尺寸的差异通过调整不同织物的编织针数比例实现;通过织物横向拉伸的压力值,调整服装收缩量;服装纵向设计中,织物拉伸性能与皮肤形变数值的大小呈对应关系;无缝瑜伽裤的结构设计需综合考虑下肢运动特征、织物性能和无缝成形原理。该技术可以应用于其他类型的运动服装设计中,有助于提高服装结构设计的科学性和生产效率。     

织物防紫外线性能测试仪的研制

为了测试和评价纺织品的防紫外线性能,详细介绍了基于 GB/T18830—2002《纺织品防紫外线性能的评定》研制的织物防紫外线性能测试系统的组成、基本功能,并对其功能的实现、考核及应用做了分析.该测试系统以紫外分光光度计为基础,通过专用的织物样品夹持架便于测试样品不同部位,通过 RS232通讯口将测试数据传送到计算机中,由专门研制的软件系统进行处理;测试系统给出织物的 UVA、UVB紫外线透过率、紫外线防护系数 UPF 值,以及不同波长下紫外线透过率曲线图;具有操作简单、测试速度快、精度高、仪器稳定性好的优点;但织物均匀性较差时,不同测试部位得到的测试结果可能会相差比较大,应通过增加测试部位和次数来改善测试结果     

Effects of environmental factors and agricultural techniques on antioxidantcontent of tomatoes

Antioxidants are believed to be important in the prevention of diseases such as cancer and cardiovascular disease. Lycopene is one of the main antioxidants to be found in fresh tomatoes and processed tomato products. The lycopene content also accounts for the redness of the fruit, which is one of the main qualities for which industry and consumers now look. Other carotenes (such as β‐carotene), vitamin C, vitamin E and various phenolic compounds are also thought to be health‐promoting factors with antioxidant properties. Since the antioxidant content of tomatoes may depend on genetic factors, the choice of variety cultivated may affect the results at harvest. To be able to control the antioxidant content of tomatoes at the field level when growing a given variety, it is necessary to know the effects of both environmental factors and the agricultural techniques used. Temperatures below 12 °C strongly inhibit lycopene biosynthesis and temperatures above 32 °C stop this process altogether. The effects of the temperature on the synthesis of other antioxidants have not yet been properly assessed. The effects of light have been studied more thoroughly, apart from those on vitamin E. The effects of water availability, mineral nutrients (nitrogen, phosphorus, potassium and calcium) and plant growth regulators have been studied, but results are sometimes contradictory and the data often incomplete. During the ripening period, lycopene content of tomatoes increases sharply from the pink stage onwards, but no sufficient attempts have been made so far to assess the changes in the other antioxidants present in the fruit. This paper reviews the present state of the art. Copyright © 2003 Society of Chemical Industry     

Measure the Dissolved Oxygen Consumed by Red Wines in Aging Tanks

The techniques of accelerated wine aging imply the addition of wood pieces of oak to the wine and the use of small doses of oxygen (micro-oxygenation). The dosage of extremely small amounts needs the knowledge of the dissolved oxygen (DO) at every moment in order to assure its correct assimilation. This work presents the first results of a study about the evolution of the dissolved oxygen content in red wines during alternative accelerated aging. Samples were treated in stainless steel vessels with wood pieces and low micro-oxygenation levels. French oak was applied with different toasting levels: light, medium, and high. Quality parameters of the wine were monitored. The knowledge of wine DO levels allowed developing a controlled micro-dosage in the different phases during the accelerated aging. The wine was able to use the whole amount of oxygen provided throughout the process.     

Headspace solid‐phase microextraction analysis of artificial flavors

Using a non‐equilibrated solid‐phase microextraction/gas chromatography/mass spectrometry technique, differentiation between a wide variety of types and examples of artificial flavors has been demonstrated. Addition of an internal standard to the samples, as received, allowed for the calculation of yields on a µg g^?1 basis for the majority of headspace volatiles. The relative standard deviation values expressed as percentages were between 3 and 5%. The precise nature of the approach coupled with the compound identification capacity of the mass spectrometer afforded the capability to easily differentiate between multiple sources of artificial flavors. With a total analysis time of approximately 30 min and the absence of solvent, this approach has the capability of detecting and quantifying the presence of the low‐molecular‐weight solvents often used in the preparation of artificial flavors. Such a capability represents a distinct advantage over more conventional methods of solvent dilution. Results from conventional gas chromatography/mass selective detector analyses are contrasted and compared with the results obtained from the headspace SPME approach. Copyright © 2005 Society of Chemical Industry     

纺纱牵伸胶辊胶圈应用技术概要

阐述棉纺牵伸胶辊、胶圈的应用技术和牵伸原理,重点探讨了胶辊、胶圈的牵伸工艺特性及其合理配置、胶辊制作、周期管理、质量管理、使用管理、产品缺陷与其机械波分析、纺纱环境和挡车工操作水平对纺纱性能的影响,提出胶辊、胶圈有关机件的质量要求等。     

工商交接备货烟叶等级质量分析

本文根据全国烟叶工商交接等级质量监督检查资料对商业备货烟叶等级质量问题进行了分析。结果表明,不同备货单位间等级质量有很大差异,而且商业企业备货的烟叶等级质量决定工商交接烟叶等级合格率的高低。等级质量问题分析表明,备货烟叶等级合格率不高的主要原因是存在混部位、混颜色、混等级等现象。在原等级中混低的比例远远高于混高的比例,调拨量大、价格较高的烟叶等级合格率较低,中部烟叶等级合格率显著低于上部和下部。本文对提高烟叶等级质量也提出了有关建议。     

集体落纱快装纱管用铝杆锭子设计

为提高空纱管安装效率,分析集体落纱细纱机特点,介绍了锭子杆盘结构型式,说明目前国内铝杆锭子多采用支持器弹簧加支持器帽的结构,虽能基本满足集体自动落纱细纱机的生产需要,但仍存在机械手安装空纱管时动作较多、动作精度不高、且易撞到锭子问题,易对锭子造成损坏并缩短锭子使用寿命的缺陷,重点对新设计的快速安装纱管的铝杆锭子的结构及原理进行分析,指出将弹簧支持器帽换成钢珠,可以大大缩短集体落纱细纱机机械手安装空纱管时间、降低对机械手动作精度的要求,且不损坏锭子、不影响锭子使用寿命,实现了节能降耗、安装效率高的目的。     

Composition and properties of seeds and pods of the tree legume Prosopis juliflora (DC)

Seeds and whole pods of Prosopis juliflora were analysed for proximate composition, fatty acids, minerals and soluble sugars. Crude protein constituted 35 % and 10 % of the seeds and whole pods, respectively. Nitrogen free extracts (NFE) comprised approximately 45 % of the seeds and whole pods. In the case of the pods, sucrose represented approximately 75 % of the soluble sugars. The lipid of both the seeds and whole pods contained a relatively large proportion of unsaturated fatty acids with linoleic acid as the predominant fatty acid. Levels of the macronutrients Ca, Mg, K and P were relatively low in comparison with cultivated legumes. Alkaline extraction of the seeds and whole pods showed that more than 70 % of the proteins were extractable. Maximum precipitation of the proteins was observed in the pH range 4.0-4.5. Amino acid analysis of the isolated proteins showed relatively high levels of lysine (312mg g^?l N for the seed and 438 mg g^?l N for the pod protein) and adequate levels of valine, leucine, tyrosine and phenylalanine. Methionine was the most limiting amino acid. The in vitro enzymic digestibility of the proteins of Prosopis seed was comparable to that of proteins of other legume seeds.     

Some Textile Applications of Finite-element Analysis Part I: Finite Elements for Aligned Fibre Assemblies

A new approach to the application of finite elements to aligned-fibre-assembly problems is introduced. This more rigorous application of finite-element analysis will allow the solution of a range of problems that have been impossible to solve by using previous approaches. Difficulties with non-linear material properties and large-scale deformations are overcome by defining the element stiffness matrix in a co-ordinate system based on the energy modes of the element deformation. It is shown how algorithms can be used to supply non-linear relationships for various types of deformation, simplifying the task of using complex material properties. The transformation of the element properties back to a conventional co-ordinate system to allow assembly of all of the elements in the structure is presented.

A two-dimensional element is developed to model aligned fibre assemblies. To maintain fibre continuity between finite elements, twelve degrees of freedom are required for each element. The deformation modes of this element are derived in terms of the conventional co-ordinate system. The results from the finite-element analysis are compared favourably with measurements taken from a deformed array of springs.

This paper is the first part of a series of two papers. Part II will investigate the application of finite elements to yarn mechanics.     

The interactions between oil droplets and gel matrix affect the lubrication properties of sheared emulsion-filled gels

In this work the lubrication behaviour of emulsions, gels, and emulsion-filled gels was studied in relation to their composition and structure. It was found that emulsions had much lower friction coefficients than their continuous phases. Emulsions with 40 wt% oil had the same friction coefficient as the pure oil. The lubrication properties of the gels, sheared by pressing them through a syringe, strongly depended on the molecular properties of the gelling agent and on the breakdown behaviour of the gel matrix. For each type of emulsion-filled gel, the lubrication behaviour was affected by the interactions between oil droplets and matrix. For gels containing oil droplets bound to the matrix, the friction coefficient gradually decreased with increasing oil concentration. For gels containing oil droplets non-bound to the matrix, the friction coefficient of the filled gels was lower than that of the same gel matrix without oil. However, no effect of the oil concentration on friction was observed. The different effects of the oil concentration on the lubrication behaviour of the various gels were explained by the relation between droplet–matrix interactions and the ‘apparent viscosity’ of the sheared gels. For gels with bound droplets, increasing the oil concentration resulted in an increase of the ‘apparent viscosity’ of the sheared gel. For gels with unbound droplets, the oil concentration did not affect the ‘apparent viscosity’. Confocal laser scanning microscopy (CLSM) observations of both emulsions and filled gels did not reveal coalescence of the oil droplets as a result of the shear treatment inherent to friction measurements.     

Chemo-enzymatic synthesis of bioactive glycopeptide using microbial endoglycosidase

The chemo-enzymatic synthesis of a glycopeptide, which involves the chemical synthesis of N-acetylglucosaminyl peptide and the enzymatic transfer of oligosaccharide, is described. The first step of the chemo-enzymatic method is the chemical synthesis of N-acetylglucosaminyl peptide with an N-acetylglucosamine moiety bound to the asparaginyl residue of the peptide by a solid-phase method. The second step is transglycosylation of a complex-type oligosaccharide derived from a glycopeptide to an N-acetylglucosaminyl peptide by endo-beta-N-acetylglucosaminidase of Mucor hiemalis (Endo-M). Peptide T can block HIV infection of human T cells. We added the sialo-complex-type oligosaccharide to chemically synthesized N-acetylglucosaminyl Peptide T using the transglycosylation activity of Endo-M. The glycosylated Peptide T thus produced showed a higher degree of resistance to protease digestion than Peptide T. We also prepared calcitonin glycopeptide. Calcitonin is a calcium-regulating hormone that is widely used in therapy for hypercalcemia, and is glycosylated by the chemo-enzymatic method described above. This glycopeptide demonstrated sufficient physiological activity. Comparison of NMR data between native calcitonin and calcitonin glycopetide revealed that the glycosylation does not affect the binding topology of the peptide. N-Acetylglucosaminyl glutamine was also a good glycoside acceptor of Endo-M. We were able to add the sialo-complex-type oligosaccharide to the glutamine residue of the Substance P neuropeptide using the transglycosylation activity of Endo-M. The glycosylated Substance P was biologically active, although its activity was rather low, and stable against peptidase digestion. The oligosaccharide moiety attached to the l-glutamine residue of the peptide was not liberated by PNGase that liberated asparagine-linked oligosaccharide from glycopeptides.     

Postmortem breakdown of ATP and glycogen in ground muscle: A review

The postmorte metabolism of ATP and glycogen in ground bovine muscle (in some cases also in rabbit muscle) was studied. At pH 7 protons released during postmortem glycolysis are bound by the phosphorylation of ADP to ATP and are liberated during enzymic hydrolysis of ATP. At lower pH values the protons are immediately released during glycolysis. Not more than 10% of the total drop in pH postmortem is due to protons liberated by the hydrolysis of ATP present in the tissue at death. Half of the buffering capacity of bovine muscle is caused by the myofibrillar proteins. The myofibrillar ATPases, rather than the membrane ATPases, seem to predominate in hydrolysing ATP postmortem in the intact as well as in the ground muscle. The rate of the breakdown of ATP determines the rate of postmortem glycolysis. Phosphofructokinase and, to a lesser extent, phosphorylase play the major role in the control of glycolytic metabolite levels in ground muscle. The mean values of glycogen recovery, obtained by measuring all glycolytic metabolites and lactate, indicate a general stoichiometric relationship in ground tissue, although several muscles did not fit in the scheme. Grinding of the prerigor muscle causes an accelerated hydrolysis of ATP and ADP, resulting in a faster increase in the IMP concentration and in an accelerated glycolysis. The increase in the turnover of ATP by grinding might be due to a faster release of Ca(++) ions from the damage sarcoplasmic reticulum. Addition of sodium chloride (2-4%) to the ground pregidor muscle causes an increase in the rate of the breakdown of ATP to IMP. NaCl changes the steady-state of glycolysis without a major change in the rate of glycogen breakdown. The stimulation of phosphofructokinase observed is probably due to the faster disapearance of ATP in the presence of NaCl. The faster turnover of ATP could be due to an enhanced release of Ca(++) ions from the sarcoplasmic reticulum by exchange against Na(+) After several hours postmortem an inhibition of glycolysis occurs in the salted tissue which is probably due to a denaturation of glycolytic enzymes by the combined effect of low pH (<6) and high ionic strength. The high water-holding capacity of prerigor salted ground beef does not decrease postmortem in spite of the high rate of ATP breakdown. This effect can be explained by an inhibition of rigor mortis in the fibre fragments caused by the combined effect of ATP, high pH and salt ions. Addition of diphosphate to the prerigor ground tissue in the absence or presence of added NaCl results in an acceleration of ATP and glycogen breakdown. A hypothesis for the high ATP turnover is discussed. The higher rate of glycogen breakdown in the presence of diphosphate is caused mainly by an acceleration of the phosphofructokinase step. A rate limitation, by diphosphate, in the glyceraldehyde-3-phosphate dehydrogenase step and/or the following glycolytic steps was also observed.     

America's First Connoisseurs of Chocolate

The global chocolate market is structured around the sale of cacao seeds for the production of solid chocolate. In Mesoamerica, where the custom of drinking chocolate enjoys an antiquity that can be traced back to the first millennium B.C., chocolate is consumed both as a beverage and as solid bricks. Archaeological evidence from a cacao-growing area in the Maya Lowlands—the Sibun Valley—suggests that during the first millennium A.D., cacao producers became entangled in the political schemes of powerful rulers with an appetite for chocolate. Epigraphic and ethno-historical sources indicate that substantial amounts of human energy were expended in the cultivation and transport of sacks of cacao beans. Female-gendered labor employed in the preparation and serving of the chocolate drink appears to be a tradition with deep antiquity regardless of whether the preparation took place in a modest home or as part of a royal banquet. Connoisseurship associated with chocolate drinking at Classic Maya royal courts is made particularly explicit by virtue of iconographic and hieroglyphic sources. These early connoisseurs of chocolate provide an illustration of the deep antiquity of our appetite for cacao and also of the profoundly entangled linkages between food and power.     

11—AN INVESTIGATION OF THE AIR-JET BULKING PROCESS

Experiments aimed at investigating the mechanism of the air-jet bulking or texturing process led to an interesting observation that the textured yarn emerging from the venturi was rotating in such a way as would temporarily untwist the yarn while it was in the jet. The indication is that false-twisting (or untwisting) occurs owing to the vorticity of the turbulent air in the wake of the yarn feed needle that bifurcates the air-stream. The various yarn-processing conditions separately affect the amount of false twist inserted. There is evidence to show that the direction of the vortex, and hence of the untwisting action, is dependent on whether the angular displacement of the feed needle from its central position is in a clockwise or anti-clockwise direction. A suggested mechanism of the process based on the untwisting and retwisting of the overfed filaments offers an explanation for the characteristic locked-in loop structure of air-bulked yarns.     

金属针布高速轧机同步张力调节装置研讨

为了倡导高速轧机的改造设计和新型轧机的创新设计,实现轧制时借助张力掌控坯片的宽展和总高余量,从金属针布高速轧机制片的典型案例入手,介绍了同步张力调节装置结构特点,通过对浮动张紧轮进行受力分析,导出了坯片张力与张紧轮浮动升力、浮动位置、坯片夹角之间的力学关系,展现了张紧轮在不同浮动位置及不同浮动升力条件下坯片张力的巨大差异;通过坯片张力对坯片轧制变形区材料流动影响的分析,强调控制坯片张力在高速轧制片中的重要性;针对原同步张力调节装置缺陷,设计出大垂距小夹角弹压可调试和大垂距小夹角重锤可调试两种新型张力调节装置。指出：轧制中坯片张力显著影响着变形效果;实际轧制中张力控制对提高轧机开台率、节约主材,降低成本、提高坯片质量有重要作用;原有轧机的改造和新型轧机的设计值得关注及研讨。