流动电流测试仪测量机理及其在造纸中的应用

简要论述了流动电流测试仪的原理、构造、解析其结果的前提假设以及现在世界上对该仪器的使用情况。解析流动电流测量结果的前提假设有两个 :其一为流动电流是由那些影响重大的成分产生的 ;其二为阳性和阴性大分子或胶体不会共存 ,悬浮液中的物质所带的电荷能够完全接触。     

造纸湿部电荷的检测技术

随着造纸工业的发展,各类造纸化学品的相继使用,使得造纸湿部的电荷变化日趋复杂,而湿部的电荷分析是应付纸机各种变化的一种有力工具,达到优化和稳定造纸湿部的目的.主要介绍了胶体电荷检测的动电学现象和胶体滴定法,并且对这两种方法的原理、特点和在线电荷的测量以及电荷分析的意义进行了讨论.     

利用胶体滴定对纸浆悬浮液进行电荷分析

介绍了利用胶体滴定技术进行电荷分析的方法，对多种纸浆的可溶电荷需求量、表面阴电荷需求量、表面阳电荷需求量和胶体滴定比率进行了测定，研究了纸浆PH值、电导率、浓度和打浆度对胶体滴定测得电荷密度的影响。对利用胶体滴定法进行纸浆悬浮液电荷分析的条件提出了建议。     

针对气体传感器电压输出信号的无线传输电路论述

国家经济发展以及科学技术进步的同时,也推动了人们生活水平的提高,与此同此,环境污染也开始日益加重。本文针对用于环境污染监测的气体传感器电压输出信号的无线传输电路展开探讨和分析,本文针对一个无线传输进行设计,从而使其满足输出信号为电压信号的传感器,进一步实现自动控制。此次电路设计具有传输距离长以及控制方便等优点。IC主要包括了无线收发模块、单片机以及数模转换芯片,电压测量的范围为0V到5V,分辨率为20mY,工作频率为433MHz,收发电流在40mA以下,待机电流约为20μA。     

应用流动电流测试仪测量湿部电荷的机理研究（译文）

本文探讨了一种电荷测量方法的实验室研究--使用流动电流检测仪(SCD)进行聚合电解质滴定.通过这些研究结果,使造纸厂中电荷测量结果难以比较的原因逐渐变得明显.实验室中该技术可以和Britt罐保留测定法结合使用,对高聚物、纸浆和填料之间反应机理进行探索.本文还讨论了三种不同高聚物的在检测中各自的行为,并重点讲述了它们作用机理的不同之处.     

用胶体滴定法测定聚合物的电荷

研究了胶体滴定法测定聚合物的带电状况和测定条件。结果表明：胶体滴定是一种方便,快速,准确的测定带电聚合物电荷密度的方法,能测定整个ｐＨ值范围的带电聚合物的电荷密度,并讨论了影响胶体滴定测定聚合物电荷的因素。     

潜油电泵井下温度压力监测系统研究

文章针对潜油电泵井下温度压力监测系统进行研究。地面系统利用星点等势法为井下监测系统提供所需的直流电压,并将采集到的电流信号实时处理和传输,从而实现对潜油电泵井下工作状态的在线监测。井下监测系统将传感器信号通过预处理,转换为电流信号后利用铠皮通道传输至地面。同时通过不同的地面系统供电电压来对压力和温度的测量进行切换。实验表明,本系统采用的供电方式简便,信号传输效率高,地面数据处理电路可靠性高,其为优化潜油电泵井下开采提供了可靠的技术支持。     

重新评价电荷测量技术 第1部分：流动电流

本文讨论了流动电流广泛应用于测定白水或浆料滤液的电荷需求量的终点判定。认为“流动电流检测器没有任何确认的理论基础”，但文中给出了要获得可信度高的流动电流结果所需要遵循的实验条件范围。另外还弄清楚了实验干扰因素的几个特定来源。     

CPAM助留作用的电荷分析研究

利用胶体滴定和测定Zeta电位相结合的方法分析了添加CPAM时浆料的电荷和电位。结果表明:添加CPAM后,浆料Zeta电位增大,可溶净电荷变化不大,胶体滴定比值(CTR)明显增大;浆料的留着性能与电荷状况之间存在一定关系。     

固着剂复配控制废纸浆溶解与胶体物质的研究

在相对而言低分子量低电荷密度的聚胺固着剂PAL中复配入不同比例的高分子量高电荷密度的聚胺固着剂PA_H,将它们作用于废纸浆,并测定纸浆体系浊度、阳离子需求量、胶体粒子数量、尺寸及尺寸分布的变化,综合考察了固着剂的复配对其控制纸浆中溶解与胶体物质性能的影响。研究结果表明:在低分子量低电荷密度的聚胺固着剂PAL中复配入约40%的高分子量高电荷密度聚胺固着剂PAH,将明显增加前者控制溶解与胶体物质的效果。反之,在高分子量、高电荷密度的固着剂PA_H中复配入比例约20%的低分子量低电荷密度固着剂PAL,并不降低前者控制溶解与胶体物质的效果。从两种固着剂具有不用作用机理的角度对上述现象进行了一定的解释。     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.     

Analysis for organic residues from aids to polymerization used to make plastics intended for food contact

Polymers intended for food contact use have been analysed for organic residues which could be attributed to a range of substances employed as polymerization aids (e.g. initiators and catalysts). A wide range of polymers was extracted with solvents and the extracts analysed by gas chromatography-mass spectrometry (GC-MS). The overwhelming majority of substances identified were not derived from aids to polymerization but were oligomers, additives and adventitious contaminants. However, a small number of substances were identified as initiator residues. These included tetramethylsuccinonitrile (TMSN) which was observed in two polymers and it derived from recombination of two azobisisobutyronitrile (AIBN) initiator radicals. Methyl benzoate, benzoic acid, biphenyl and phenyl benzoate were detected in one poly(methyl methacrylate) sample and in two polyvinylchlorides and they are thought to be derived from benzoyl peroxide initiator. TMSN was subsequently targeted for analysis of poly-(methyl methacrylate) plastics using proton nuclear magnetic resonance spectrometry (¹     

Tests of potential functional barriers for laminated multilayer food packages. Part II: Medium molecular weight permeants

Experiments were performed to characterize the kinetics of the permeation of different medium molecular weight model permeants: bisphenol A, warfarin and anthracene, from liquid paraffin, through a surrogate potential functional barrier (25 microns-thick orientated polypropylene--OPP) into the food simulants olive oil and 3% (w/v) acetic acid. The characterization of permeation kinetics generally observed the permeation models previously reported to explain the experimental permeation results obtained for a low molecular weight group of model permeants. In general, the model permeants exhibited behaviour consistent with their relative molecular weights with respect to (a) the time taken to attain steady-state permeation into the food simulant in which they were more soluble, (b) their subsequent steady-state permeation rates, and (c) their partition between liquid paraffin and the OPP membrane.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. I: Interlaboratory studies of methods of analysis

This paper describes the first part of a project undertaken to develop mussel reference materials for Paralytic Shellfish Poisoning (PSP) toxins. Two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX) in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the second part of the project: the certification exercise. In the first study, 18 laboratories were asked to measure STX and dc-STX in rehydrated lyophilized mussel material and to identify as many other PSP toxins as possible with a method of their choice. In the second interlaboratory study, 15 laboratories were additionally asked to determine quantitatively STX and dc-STX in rehydrated lyophilized mussel and in a saxitoxin-enriched mussel material. The first study revealed that three out of four postcolumn derivatization methods and one pre-column derivatization method sufficed in principle to determine STX and dc-STX. Most participants (13 of 18) obtained acceptable calibration curves and recoveries. Saxitoxin was hardly detected in the rehydrated lyophilized mussels and results obtained for dc-STX yielded a CV of 58% at a mass fraction of 1.86 mg/kg. Most participants (14 out of 18) identified gonyautoxin-5 (GTX-5) in a hydrolysed extract provided. The first study led to provisional criteria for linearity, recovery and separation. The second study revealed that 6 out of 15 laboratories were able to meet these criteria. Results obtained for dc-STX yielded a CV of 19% at a mass fraction of 3.49mg/kg. Results obtained for STX in the saxitoxin-enriched material yielded a CV of 19% at a mass fraction of 0.34mg/kg. Saxitoxin could not be detected in the PSP-positive material. Hydrolysis was useful to confirm the identity of GTX5 and provided indicative information about C1 and C2 toxins in the PSP-positive material. The methods used in the second interlaboratory study showed sufficiently consistent analysis results to undertake a certification exercise to assign certified values for STX and dc-STX in lyophilized mussel.     

Focus on China's Paper Industry

In the English section of this issue, 〈China Paper Newsletters〉 will introduce ＂National Development and Reform Commission Issued Announcement for Selection of Major Preliminary Research Projects for the ＇13th Five-Year Plan＇＂, ＂2013 Annual Report of China＇s Paper Industry＂, and news of projects and other policies.     

Listen to downstream & search for innovation

正Nowadays,textile enterprises are all taking efforts in transformation and upgrading,like improving producing capacity and optimizing production structure to face market downturn.It claimed a higher request to the standard of textile equipments.In the upcoming of ITMA ASIA+CITME 2014exhibition,this magazine have interviewed several branch associations and a series of relative enterprises,to summarize industrial developing status