造纸助留剂及其应用

l前言随着造纸技术的不断发展，对造纸化学品的应用提出了更高的要求。进入80年代以来，造纸化学领域发展最突出的是在助留助滤剂方面的研究开发与应用，特别是在微粒子双元助留体系上。它的应用革新了传统的留着技术和观念。在纸机的湿部控制系统中，造纸助留剂的应用已越来越为人们所关注。造纸助留剂作为用来改善纸浆在纸机网部留着的化学助剂，它通过助留和助滤可以影响整个抄纸过程，产生广泛的技术和经济效益。可以说，助留剂是一种功能最强，应用面最广的湿部化学助剂。2助留剂的类型及其作用机理2.l无机类助留剂最重要的无机类助留…     

造纸湿部化学的进展

随着现代造纸工业中高速纸机、双网成形、封闭白水系统、废纸利用和中性造纸等新技术的发展，造纸湿部化学领域的研究与应用取得了令人瞩目的进展。本文论述了湿部化学的基本原理和湿部化学品的发展状况，探讨了湿部化学过程控制方面的发展趋势。     

湿部化学品的发展状况

随着现代造纸工业中高速纸机、双网成形、封闭白水系统、废纸利用和中性造纸等新技术的发展，造纸湿部化学领域的研究与应用取得了令人嘱目的进展。本文系统的论述了湿部化学的基本原理和湿部化学品的发展状况。     

湿部化学品的发展状况

随着现代造纸工业中高速纸机、双网成形、封闭白水系统、废纸利用和中性造纸等新技术的发展,造纸湿部化学领域的研究与应用取得了令人瞩目的进展。该文系统地论述了湿部化学的基本原理和湿部化学品的发展状况。     

纸料表面电菏的测定

近年来，随着中性施胶技术在造纸工业的应用，中性造纸得到了迅速的发展，与此同时，造纸湿部化学的研究也引起了造纸科技工作者越来越多的关注与兴趣，造纸湿部化学的研究核心是湿部化学品的添加与控制及其对纸张性能、纸机运行性能的影响，留着率和电菏测定是研究湿部化学过程的最重要手段，通过测量造纸配料的表面电菏及网部留关着率可检测出湿部化学的变化，从而及时有效地指导调整湿部化学品的添加点与添加量，从而改善纸机的运转性能及提高湿部添加剂的使用效率。     

纳米技术在造纸湿部的初步应用效果

本文扼要介绍了纳米技术和造纸湿部化学的概念，以及在纸机湿部应用阴离子胶态氧化硅（ACS）生成纳米氧化硅粒子的性态及其在高速纸机生产中取得的实际效果。     

纸料表面电荷的测定

1前言 近年来,随着中性施胶技术在造纸工业中的应用,中性造纸得到了迅速的发展.与此同时,造纸湿部化学的研究也引起了造纸科技工作者越来越多的关注与兴趣.造纸湿部化学的研究核心是湿部化学品的添加与控制及其对纸张性能、纸机运行性能的影响.     

第一期造纸化学品开发应用技术研讨班即将举办

中纸造纸化学品协作中心与天津科技大学材料科学与化学工程学院定于2002年6月中旬在天津科技大学举办“第一期造纸化学品开发应用技术研讨班”。研讨和学习制浆造纸化学品领域的具有实际应用意义的新观念、新理论、新技术、新设备,为全国制浆造纸工业企业培训中、高级技术管理,技术开发及应用人才。造纸化学品开发及应用研讨班将分别研讨目前我国造纸化学品应用的形势和发展趋势、制浆及漂白助剂、废纸再生利用、造纸湿部化学、加工纸及特种纸、废水处理等方面的实用技术、助剂及设备,以专题讲座和相互交流为主,辅以相关的应用型开发实验。…     

高速新闻纸机湿部化学的探讨

近几年来,对高速纸机湿部化学的研究,得到越来越多造纸工作者的重视。了解生产过程的化学机理,并应用这些化学机理去监控纸机的湿部所产生的经济效益已经变得越来越明显了。本文对高速新闻纸机湿部化学过程进行一些探讨,以供造纸同行参考。 1.湿部化学过程 湿部的化学过程指的是化学添加剂和纸浆在这些纸机重要部位上所发生的化学反应,以及它们在浆料中的纤维、无机填料上的吸附和解附作用,同时也包括化学品对造纸的重要环节所产生的不良影响。例如较强的凝聚作用影响到纸张的品质。 湿部是整台纸机操作过程中最复杂的环节。在这一操…     

纸机流送部杀菌剂试验

随着当前造纸工业的高度发展,纸机湿部化学的重要性更加显著,尤其是中高速纸机的生产操作上,产量、质量和效益的竞争都在湿部化学的使用上体现出来。纸机湿部化学名目繁多,其中有几种应该放在首要地位,杀菌剂（防腐剂）就是其中之一,众所周知,腐浆对造纸生产的影响非常之大,不同纸种的工艺复杂程度不同,其工艺过程中腐浆控制的难易也有不同,工艺线路越复杂,流水线越长,浆料中间储存时间越长,对腐浆控制的要求也就越高。 我们华众纸业有限公司的３＃机生产单面涂布白板纸,车速３５０米／分,年产１２万吨,从投产以来我们也使…     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

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.     

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

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

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.