口罩用聚丙烯熔喷布的结构与过滤性能研究

后新冠疫情时代,口罩已经成为人们在公共场合的必需品,聚丙烯熔喷布作为口罩三层结构中的重要组成,对防护效果和舒适程度起到了决定性的作用。本文通过系统测试随机收集的20个聚丙烯熔喷布样品的基本参数、微观形貌、过滤性能、通气阻力、透气性和透湿性,研究了熔喷布的纤维直径及其均匀程度和孔隙率等结构参数与上述性能之间的内在联系,得到如下结论：过滤效率、通气阻力和透气性均受熔喷布中纤维直径及其均匀程度的影响,纤维直径越小、越均匀,熔喷布的盐性/油性颗粒物过滤效率和透气性能越好,通气阻力越低,且熔喷布孔隙率与其通气阻力和透气性之间存在线性关系;纤维直径及其均匀程度对于透湿性的影响较小,过滤效率和透湿性与熔喷布孔隙率之间均未呈现稳定的变化趋势。     

非织造医用防护口罩过滤材料结构与过滤效率关系的研究

为了制备高效低阻的医用防护口罩,对医用防护口罩、医用外科口罩、医用颗粒物防护口罩和一次性医用普通及护理口罩4大类共8种非织造医用防护口罩的厚度、面密度、孔隙率、平均孔径、纤维直径和过滤性能进行了测试,研究了各结构参数对过滤效率的影响。研究表明:随着过滤材料厚度、面密度的增大,过滤效率随之增大;随着平均孔径和纤维直径的减小,过滤效率呈增大趋势;过滤效率随孔隙率的变化规律性不强;经SPSS多元回归分析,5个结构参数对过滤效率的影响权重依次为:平均孔径纤维直径平均厚度孔隙率面密度。     

溶剂对聚乳酸纳米纤维膜孔隙结构及性能的影响

为了获得兼具高效低阻和良好透气、透湿性能的纳米纤维膜材料,将聚乳酸(PLA)溶解在二氯甲烷(DCM)和N,N-二甲基乙酰胺(DMAC)形成的混合溶剂中,采用静电纺丝技术制备PLA多孔纳米纤维膜,并系统研究了DCM/DMAC质量比对纤维膜形态结构、透气性能、透湿性能和空气过滤性能的影响。结果表明:"呼吸图案"效应和热致相分离是纤维表面形成孔洞的主要机制,随着DCM含量的增加,纤维表面孔隙覆盖率逐渐增大,纤维膜的透气率先降低后升高,透湿率略有提高,过滤效率逐渐上升,阻力压降则先增大后减小,品质因子持续变大,说明在纳米纤维中形成多孔结构有助于改善材料的透气、透湿性能,并可以实现高效低阻的过滤效果,在口罩用过滤材料领域具有广阔的应用前景。     

熔喷非织造过滤材料直径对医用口罩过滤性能的影响

为研究熔喷非织造过滤材料直径对医用口罩过滤性能的影响,指导高效低阻的医用防护口罩的制备,对医用防护口罩、医用外科口罩、医用颗粒物防护口罩和医用普通及护理口罩四大类共7种非织造医用口罩的纤维直径和过滤性能进行了测试,研究了直径对过滤效率的影响。研究表明:纤维直径越小,过滤效率越高;纤网的直径粗细不均匀时,直径变异系数越大,过滤效率越高。     

静电纺高效防尘复合滤料的制备及其性能

为获得无毒无害高效防尘口罩的过滤材料,采用静电纺丝技术制备直径为（0.088±0.01）μm的锦纶6∕ 壳聚糖（PA6/CS）共混纳米纤维,与丙纶熔喷非织造布复合形成高效防尘复合滤料,研究了静电纺丝时间对复合滤料表面形貌、孔径及其分布、过滤性能和透气透湿性能的影响。结果表明,静电纺（PA6/CS）纳米纤维层可显著提高丙纶熔喷非织造布的过滤效率,静电纺丝 90 min 后复合滤料对 NaCl 气溶胶的过滤效率达到99%以上,明显高于丙纶熔喷非织造布的过滤效率（29%）,但是随着静电纺丝时间的延长,复合滤料的孔径、过滤阻力和透气性能明显下降,而透湿性能变化不明显。     

医用防护口罩过滤层性能的对比与分析

对国内所生产的医用防护口罩过滤层样品和国外样品的综合物理性能进行测试及分析,尤其是两者静电驻极前后的过滤效率和静电势,包括过滤层的纤维直径、透气性、过滤效率、厚度、面密度、拉伸强力、孔径和静电势等。测试结果表明,国外过滤层材料的纤维直径小且均匀性高。提出改进相应生产线从而提升产品质量的建议。     

纳米复合口罩过滤性能影响因素的正交试验分析

为了提高纳米复合口罩的过滤性能,采用静电纺丝技术,以丝胶蛋白、聚环氧乙烷为原料制备丝胶纳米复合口罩用料;设计四因素三水平正交试验,分析纳米复合口罩的过滤性能影响因素。结果表明:纺丝时间是影响纳米复合口罩过滤效率与吸气阻力的最重要因素,平均纤维直径的影响次之,而无纺布层数和无纺布克重对其影响较小。当纳米复合口罩制备工艺参数为纺丝时间10h,平均纤维直径472nm,无纺布克重20g/m2,无纺布层数为2层时,口罩的过滤效果好。     

吸附-过滤双功能复合微纳纤维的制备及性能研究

通过静电纺丝技术在活性碳纤维表面形成一层纳米孔道结构膜,制备具有吸附和过滤双功能的复合微纳纤维。测试结果表明:该纤维不仅具有活性碳纤维强的吸附能力,对常见挥发性有机污染物的吸附饱和量最高可达295.5mg/g;且静电纺丝所形成的纳米孔道结构能够有效过滤大气细颗粒物,可完全过滤0.5~10μm的颗粒物。此外,测试结果还表明,该复合微纳纤维还具有较好的透气和透湿性。并考察了静电纺丝时间对复合微纳纤维透气和透湿性的影响。     

竹浆纤维含量及纬密对竹棉织物透通性的影响

通过对15种不同规格的棉与竹/棉交织物的透通性进行测试分析,研究了竹浆纤维含量及纬纱密度变化对交织物透通性的影响规律,结果表明:随着纬纱中竹浆纤维含量的增加,竹/棉交织物的透气性能、透湿性能增强;随着纬密的增加,织物透气性、透湿性能下降;当纬密较大时,织物透气性能除受织物结构形态影响外,竹浆纤维含量的因素仍有相当的影响,但竹浆纤维含量的影响因素变小.     

梯度结构双组分纺粘水刺非织造材料的制备及其性能

为探究梯度结构对超细纤维非织造材料性能的影响,通过双组分纺粘技术和不同水针压力作用下的水刺开纤技术,用一步法制备了不同面密度（80、120、160 g/m2 ）的梯度结构双组分纺粘水刺非织造材料,并分析了水针压力对结构和透气透湿、力学、过滤性能的影响。结果表明：当面密度一定时,随着水针压力从15 MPa 的增大到28 MPa,双组分纺粘水刺非织造材料的厚度减小,平均孔径减小,透气透湿性能下降;纵/横向断裂强力先增加后减小,断裂伸长率先减小后增加;过滤效率和过滤阻力均增加,其中当面密度为80 g/m2 ,水针压力为11MPa 时,过滤效率（0.85 μm 粒径）和过滤阻力分别达到66.8%和25.1 Pa。     

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.     

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.     

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.