干燥方式对亚微米纤维复合空气过滤材料结构和性能的影响

以原纤化天丝和玻璃棉这2种亚微米纤维为原料,通过湿法成形的方式将其复合在无纺布基材上制得空气过滤材料（以下简称滤材）,探究了冷冻干燥及加热干燥对滤材结构和性能的影响。结果表明,冷冻干燥能较好地保留湿纸幅中亚微米纤维的形态,减少纤维收缩,对原纤化天丝的影响尤为显著;当原纤化天丝与玻璃棉的配比分别为2∶8、4∶6、6∶4、8∶2时,冷冻干燥滤材的过滤效率分别比加热干燥滤材的过滤效率高3.5%、5.5%、9.8%和12.2%,过滤阻力分别比加热干燥滤材低20.4%、28.1%、23.3%和33.2%。可见冷冻干燥可显著提高亚微米纤维复合空气过滤材料的过滤效率,降低其过滤阻力。     

天丝纤维在变压器绝缘纸板中的应用

天丝纤维是一种溶剂型再生纤维素纤维,研究了天丝纤维原纤化程度及其对浆料性能的影响,探讨了天丝纤维与针叶木浆配抄对变压器绝缘纸板机械性能和电气性能的影响。研究结果表明,天丝纤维容易原纤化,原纤化程度越高,纤维变得更加柔软和扭曲,表面更加粗糙,分丝帚化越多;相对100%针叶木浆抄造的绝缘纸板,针叶木浆与天丝纤维配比为85∶15配抄的绝缘纸板的紧度降低4.8%,抗张指数下降2.9%,吸油率提高11.9%,在空气中的击穿电压提高5.8%,在油中的击穿电压提高25.8%,天丝纤维显著提高了绝缘纸板的吸油率和电气强度。     

漂白硫酸盐竹浆与阔叶木浆PFI磨浆特性的对比研究

本研究主要利用PFI磨浆机对漂白硫酸盐竹浆与阔叶木浆的磨浆特性及其成纸性能进行对比研究。研究发现相同磨浆转数下,竹浆打浆度略高于阔叶木浆,湿重比阔叶木浆高;磨浆前期（打浆度低于35．5°SR）,相同打浆度下,竹浆纤维成纸的抗张指数低于阔叶木浆,而后随着打浆度的增加,竹浆纤维成纸的抗张指数高于阔叶木浆。相同打浆度下,竹浆...     

桉木PFI磨浆过程中纤维形态的变化

用扫描电镜和多媒体纤维镜观察桉木浆PFI磨浆过程中纤维的变化。观察发现:桉木浆磨浆前期,纤维开始分丝帚化,纤维次生壁S1层的微纤维逐渐剥离下来,纤维被严重切断;磨浆中期,纤维次生壁S2层的微纤维逐渐剥离下来,纤维以分丝帚化为主,同时被切断;磨浆后期,纤维次生壁S3层的微纤维缓慢地剥离下来,纤维分丝帚化和切断的速度缓慢。     

磨浆pH控制对装饰原纸遮盖性能的影响

通过进行不同组别的单一变量对照实验来研究不同p H下打浆对装饰原纸遮盖性能与原纸和浸胶压板亮度的影响。实验结果表明：在不影响装饰原纸成纸p H的前提下，在比较高的p H条件下进行磨浆处理的漂白阔叶木浆纤维分丝帚化度与扭结度都较好，与成品钛白粉等无机物填料的结合度上升。综合来看有利于钛白粉等填料在纤维上的附着。     

打浆工艺对造纸法再造烟叶基片松厚度的影响

采用PFI磨对烟草浆进行打浆,分别研究了磨浆转数、磨齿间隙和打浆浓度对造纸法再造烟叶基片松厚度的影响,同时通过对不同打浆参数条件下得到的烟草浆纤维形态的对比,探讨了打浆工艺对造纸法再造烟叶基片松厚度的影响。结果表明,烟草浆打浆过程中,随着磨浆转数的减少,磨齿间隙的增加以及打浆浓度的提高,纤维数量下降、平均长度上升、粗度增加,与木浆、轻质碳酸钙混合抄造出的基片松厚度提高;在本实验打浆工艺范围内,磨浆转数和磨齿间隙对烟草浆纤维形态以及抄造出的基片松厚度的影响大于打浆浓度的影响;由于烟草浆纤维本身的特点,不同的打浆工艺对其帚化效果影响很小;适宜的PFI磨打浆工艺为:磨浆转数10000~15000转,磨齿间隙0~0.5 mm,打浆浓度10.0%~11.7%。     

原纤化Tencel纤维对滤纸性能的影响

对Tencel纤维随打浆强度的变化进行了研究;对比了相同质量分数下,高原纤化Tencel纤维和玻璃棉分别与木浆纤维复配抄纸的成纸的物理性能和过滤性能.结果表明,随着打浆强度的提高,Tencel纤维的形态会发生显著改变,最终出现大量原纤;Tencel纤维和玻璃棉纤维分别与木浆复配后,所得纸样的透气度和孔径接近,但玻璃棉复配纸样的多通过滤性能较优,而高原纤化Tencel纤维复配纸样则有明显的强度优势.     

MFC负载铁离子催化对纸浆纤维的芬顿表面氧化作用研究

将富含铁离子的微纤化纤维素（MFC-铁离子）吸附于漂白硫酸盐针叶木浆纤维表面,然后对纸浆纤维表面进行芬顿氧化;通过激光扫描共聚焦显微镜（LSCM）间接检测纤维上芬顿反应产生的羟基自由基（·OH）,使用扫描电子显微镜（SEM）和能谱仪（EDS）检测纤维上铁元素的分布;评价了在相同打浆转数下,芬顿表面氧化处理对纤维素平均聚合度（DP）、纤维形态及成纸抗张指数和撕裂指数的影响。结果表明,芬顿表面氧化预处理产生的·OH主要分布在纸浆纤维表面,并且基本保留了纤维平均长度;与原浆相比,芬顿表面氧化浆的纤维素平均DP仅下降约4.9%,打浆转数8000转时,成纸抗张指数和撕裂指数较原浆成纸分别提高了20.9%和25.7%。     

机械制浆工艺的原理

在低定量含机械浆印刷纸中，有3个不同的性能需要同时达到最佳化，它们是影响不透明度的光散射系数、影响强度的纤维长度和对成纸适印性产生作用的紧度。对某树种而言，不论是磨石磨木浆、盘磨浆还是硫酸盐浆，其纤维的光散射系数和纤维长度之间具有某种独特的联系。降低磨浆强度或提高化学处理程度或温度时，能减少纤维切断，提高长纤维含量。     

慈竹浆与桉木浆PFI磨浆过程中纤维形态的对比研究

用PFI磨对漂白硫酸盐慈竹浆与桉木浆进行磨浆,利用多媒体显微镜和扫描电子显微镜(SEM)观察慈竹浆和桉木浆纤维在打浆过程中纤维形态的变化。结果发现:打浆前期,慈竹浆纤维和桉木浆纤维的初生壁(P)和次生壁外层(S1)破除,分丝帚化情况大致相同;打浆中期,随着S2层微纤维的剥离,慈竹浆纤维露出S3层,分丝帚化减少;桉木浆纤维S2层微纤维持续剥离,分丝帚化增加。打浆后期,慈竹浆纤维的S3层不容易剥离出微纤维,分丝帚化不明显;桉木浆纤维S3层容易剥离出微纤维,分丝帚化明显。     

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.