纳米二氧化钛在整理液中的分散稳定性研究

研究了不同分散剂在不同条件下对纳米二氧化钛粉体在整理液中分散稳定性的影响，采用分散相的沉降高度和分散体系中粒子的粒度分布进行评价，结果表明：六偏磷酸钠、硅酸钠、NK-1是纳米二氧化钛粉体较好的分散剂．通过测定分散相在分散递质中的Zeta电位，分析了分散剂的分散机理，说明六偏磷酸钠和硅酸钠可显著提高整理液中二氧化钛颗粒表面Zeta电位的绝对值，NK-1在纳米二氧化钛颗粒表面形成良好的溶剂化层，使纳米二氧化钛颗粒在水溶液中获得优良的分散稳定性．     

Zeta电位在造纸过程中的应用

控制Zeta电位和pH对于提高造纸过程的效率,改善纸的质量,降低废液的危害有很大的作用。其成就尚在逐步扩大。 1.什么是Zeta电位 纸机湿部胶体粒子的相互作用主要是受它们的Zeta电位的影响。Zeta电位代表一种正的或负的动电荷,以毫伏表示。这种动     

不同因素对中链脂肪酸脂质体Zeta电位的影响

Zeta电位值是评价脂质体稳定性的重要指标。在前期对中链脂肪酸脂质体研究的基础上,考察磷脂种类、脂质质量浓度、表面活性剂吐温-80添加量、不同pH值、不同金属离子种类及浓度对中链脂肪酸脂质体Zeta电位的影响。结果表明:选用大豆卵磷脂,脂质质量浓度为8g/100mL,吐温-80与磷脂质量比为3:10时制备的中链脂肪酸脂质体Zeta电位的绝对值最高,为51.08mV;中链脂肪酸脂质体的Zeta电位绝对值随环境阳离子价电数、环境离子浓度的增加均逐渐减小;中链脂肪酸脂质体在偏中性(pH7、8)环境下最稳定,其Zeta电位绝对值为50mV左右,而在强酸(pH1、2)、强碱(pH13)性环境下,其Zeta电位值趋近于0mV,最不稳定。     

低分子质量聚丙烯酸钠的合成及应用

以丙烯酸、氢氧化钠等为原料,以无机磷酸盐为链转移剂合成了系列低分子质量聚丙烯酸钠分散剂.探讨了分子质量对聚丙烯酸钠分散性能的影响.研究了分散剂的最佳用量及在最佳用量条件下瓷土悬浮液的性能变化情况.     

文摘

对Zeta电位进行研究有助于揭露造纸过程中的物理—化学本质。本文是1945年到1971年期间有关Zeta电位及其在造纸工业中的应用的文献综述,共引用了102篇文献,文中有图98幅、表10个。纸浆纤维在水中带负电荷,和其他胶体粒子一样,它也具有动电电位这样的胶体电学性质,这个动电电位     

聚合硅酸硫酸铝的动电特性

利用微电泳技术对聚合硅酸硫酸铝的动电特性研究表明：聚合硅酸硫酸铝的等电点和硫酸铝相近,约为pH值5,但其所带电荷的绝对值高于硫酸铝,且碱化度和硅铝比提高,均可不同程度地提高其可测Zeta电位的绝对值;水解过程中的搅拌作用可增加聚合硅酸硫酸铝的可测Zeta电位的绝对值,但不会改变其等电点;水中杂离子使聚合硅酸硫酸铝稀释后的pH值较高,所带电荷的绝对值降低,但却使其等电点向高pH值方向移动;水解时间对聚合硅酸硫酸铝Zeta电位的测定影响不大。     

应用Zeta电位分析荧光增白剂分散体系的稳定性

为了提高荧光增白剂C.I.199分散悬浮液体系的稳定性能,通过测定其悬浮体系Zeta电位的方法,研究表面活性剂、电解质、pH值等不同因素对涤纶增白剂(22E-13)与涤棉增白剂(22EC-17)稳定性的影响。实验表明:该分散体系在一定浓度下加入阴离子表面活性剂或阴/非离子表面活性剂复配物后,产品的稳定性显著提高,但在高价金属阳离子存在时会对其产生严重的破坏;选择适当的pH值也是控制稳定性的一种方法。     

膨润土的高浓改性及微粒助留作用

利用柠檬酸钠对膨润土进行高浓改性,研究了改性方式及膨润土浓度、柠檬酸钠加入量、贮存时间等对高浓膨润土悬浮液中膨润土的膨胀容、体积平均粒度、Zeta电位的影响和高浓膨润土悬浮液对纸料的微粒助留作用。     

无机电解质对浆料Zeta电位的影响

通过改变浆料中无机电解质/阳离子聚酰胺-环氧氯丙烷树脂(PAE)的浓度,采用德国Mütek公司SZP-10型Zeta电位仪测量对比浆料Zeta电位及电导率的变化,研究无机电解质对含PAE浆料Zeta电位及电导率的影响。实验表明:随着Na+/Ca2+/Mg2+浓度的增加,浆料Zeta电位绝对值逐渐下降;随着导电离子浓度的增多,浆料电导率逐渐升高。随着PAE用量的增加,浆料的Zeta电位逐渐增加,当用量达到一定值后,Zeta电位的电性发生反转,由负变正,再继续增加PAE用量后,浆料Zeta电位继续升高。PAE用量固定在1%时,随着Na+/Ca2+/Mg2+浓度的增加,浆料的Zeta电位逐渐降低,电导率逐渐升高。     

小麦醇溶蛋白自组装纳米粒子负载白藜芦醇的性质研究

小麦醇溶蛋白是谷朊粉的主要成分之一,用小麦醇溶蛋白包埋白藜芦醇以达到稳定白藜芦醇的目的。用反溶剂法制得其自组装纳米粒子,对乙醇浓度、蛋白浓度、分散液pH、分散液盐浓度等因素对纳米粒子的粒径以及Zeta电位的影响做出了探究。发现在乙醇浓度为65%,蛋白质浓度4%,分散液pH为4.5,分散液盐浓度为0.00 mol/L时,得到理想的纳米粒子,其粒径约为(185.1±8.5)nm,Zeta电位为(19.36±1.03)m V。而后在最佳条件下用小麦醇溶蛋白纳米粒子负载白藜芦醇,发现该复合物在芯壁比为1∶40时包埋率最高,此时粒径(166.7±3.7)nm,Zeta电位(15.68±0.74)m V,包埋率为55.0%,载药率为1.5%。小麦醇溶蛋白纳米粒子可以用来稳定白藜芦醇。     

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