日常防护型口罩结构分析及性能研究

为了研究口罩结构参数对过滤性能及透气透湿性能的影响,对8种日常防护型口罩内层、过滤层及外层的结构参数进行分析,并对其透气透湿性能、过滤性能进行测试和表征.结果表明:过滤层结构参数对过滤性能的影响权重从大到小依次为:纤维直径、平均孔径、孔隙率,且随着纤维直径的减小,口罩的过滤性能呈增大趋势;口罩整体的透气性能主要受口罩内...     

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。     

摩擦驻极对聚四氟乙烯纤维非织造布过滤性能的影响

为研究聚四氟乙烯(PTFE)纤维在加工过程中的摩擦效应所产生的静电荷对非织造材料过滤效率的影响机制,制备高效低阻的非织造过滤材料。选取PTFE纤维为原料,经过短纤维梳理、针刺复合制备了不同面密度的PTFE纤维针刺非织造布,测试了摩擦驻极后0~40 d内非织造布的表面静电势以及过滤性能,并分析了针刺非织造布的电荷存储稳定性。结果表明:经过梳理、针刺加工的PTFE纤维非织造布具有很高的过滤效率和较低的过滤阻力;面密度越大,非织造布的表面电势越大,过滤效率越高,面密度为220 g/m2的PTFE纤维摩擦驻极过滤材料对0.26μm颗粒物的过滤效率可达99%以上,并且静电衰减周期较长;水浸泡对静电衰减的影响较小。     

卷烟纤维过滤咀过滤效率的研究

一、绪言已有不少的研究人员,对卷烟纤维过滤嘴的过滤作用进行了理论和实验方面的研究。并在过滤机构中的惯力、阻力、扩散等方面取得相当的进展。然而,对于纤维过滤层中的过滤机构的综合效率的研究迄今尚未达到实用的程度。我们从香烟用过滤层的生产设计角度出发,对纤维层过滤嘴的过滤性能进一步加以     

PBS静电纺非织造布结构与过滤性能的关系分析

研究了聚丁二酸丁二醇酯(PBS)静电纺非织造布结构与过滤性能的关系。采用扫描电镜和SPSS软件,测试分析了PBS静电纺非织造布的纤维直径、孔隙率等对过滤效率的影响。实验结果表明,纤维直径和孔隙率越大,非织造布透气性越好,而过滤效率越小。     

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。     

防护口罩用改性长效聚(偏氟乙烯-三氟乙烯)压电纤维膜的制备及其性能

聚丙烯(PP)熔喷布表面自由电荷易在湿气等作用下流失,导致过滤层及口罩快速失效。针对以上问题,采用静电纺丝技术在PP熔喷布基体上制备压电聚(偏氟乙烯-三氟乙烯)(P(VDF-TrFE))纤维层,得到PP熔喷布/P(VDF-TrFE)改性过滤层。探究了纺丝工艺对压电纤维形貌和结构的影响,进一步分析了改性过滤层经过水洗、蒸汽等耐久性处理后的静电压、烟雾过滤效率和透气性的变化。结果表明：PP熔喷布/P(VDF-TrFE)改性过滤层对PM_2.5的过滤效率较PP熔喷布提高了25%,在进风量为85 L/min时的过滤效率提升了27.5%;经过2次水洗、紫外线照射、蒸煮消毒等方式处理后的改性过滤层,其表面电荷具有多次弯折后可再生的特点,过滤效率维持在90%,有效提高了口罩的防护效率和使用寿命,压电材料在外力作用下可产生束缚电荷,改善了过滤层负载电荷的稳定性,从而提升了口罩防护的长效性和安全性。     

静电纺PAN纤维膜的制备及其过滤性能研究

静电纺丝滤膜具有良好的过滤性能,但是要纺制具有可控性的过滤材料,需了解纺丝参数及溶液性能与过滤性能之间的关系。首先,利用静电纺丝法制备了静电纺PAN纳米纤维膜,研究纺丝时间和纺丝液浓度对纤维膜结构和过滤性能的影响。通过扫描电子显微镜和自动滤料检测仪对PAN纳米纤维膜的形貌、过滤效率和滤阻进行了测试分析。之后研究了溶液放置时间对滤膜过滤性能的影响。研究结果表明:随纺丝时间的延长,纤维的直径变化不大,过滤效率和滤阻增加;随着纺丝液浓度的增加,纤维的直径变大,过滤效率和滤阻先增加后降低;纺丝液质量分数为10%时,滤阻较小,过滤效率高;溶液放置一定时间后,制得纤维的直径变粗,不同纺丝时间、纺丝液浓度条件下的滤膜过滤效率、滤阻均下降。     

多尺度纤维高温气体过滤材料的制备号性能研究

随着空气质量日趋恶化,用于高温废气过滤排放的滤料开发得到越来越多的关注。本研究采用多尺度纤维复合方式开发具有过滤层与机织力学增强层的高温气体过滤材料。通过静电纺丝法制备了直径约为200nm的聚酰亚胺超细纤网作为过滤层。通过织造制得2／2斜纹碳纤维机织布作为力学增强层。对聚酰亚胺超细纤网耐热性能的研究以及对多尺度纤维复合滤料过滤性能的测试,证明该过滤材料具有作为高温气体滤料的研发价值,其最大过滤效率达98．13％。通过扫描电子显微镜（SEM）观察过滤前后聚酰亚胺超细纤网的形貌,证实了过滤前均匀纤网的形成以及过滤过程中纤网对粉尘颗粒的有效拦截作用。     

汽车机油过滤用材料的结构及过滤性能

以纤维直径为3.42 及平均孔径为23.6 和孔隙率为95.07%的玻璃纤维非织造布作为过滤介质,以颗粒直径为13.076 的A3粉作为杂质颗粒,并且以动力粘度为1.275×10-2 Pa?S的YH-15机油为试验油液,利用D-30多次通过试验台模拟汽车机油滤清器的过滤过程并且测试过滤性能。建立了杂质颗粒拦截模型,根据测试结果计算出过滤材料和纤维的过滤效率以及QF值。实验结果表明,随着时间和杂质质量的增加,玻璃纤维非织造布两侧的压差增加。 玻璃纤维非织造布的过滤效率大于玻璃纤维的过滤效率,并且变化趋势相同。利用QF值能够结合压差及过滤效率两个变化参数来表达过滤效果,并且 QF值随着杂质颗粒直径的减小和过滤时间的增加而减小。     

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.     

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.     

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.     

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.     

Influence des ions sur le pouvoir hydratant de l'ure e: e tude sur peau de porc ex vivo

This study deals with the influence of ions (NaCl and MgSO4) in a W/O emulsion containing 10% urea. Moisturization kinetics are assessed by corneometry on pig skin ex vivo. The formula's influence on urea penetration is measured by infrared spectrometry with an ATR device and the stripping method. Corneometry and spectroscopy were chosen to record simultaneously the hydratation levels and urea localization into superficial cell layers. Urea crystallization after evaporation of emulsions and aqueous solutions is described. Results show that urea does not hydrate nor penetrate when applied to the skin through an aqueous gel. In a W/O emulsion, sodium chloride increases the ability of urea to moisturize without improving penetration. In vitro urea crystallization is disturbed by sodium chloride or magnesium sulphate for solutions and emulsions. This stabilization by ions is correlated with good moisturization values. The stabilization of urea in the solute state provided by ions increases its water epidermal binding capacity without enhancing penetration.     

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.     

Analysis on Economic Indicators from 62 Enterprises in Printing Machinery Industry in Q1 2014

Operation of printing machine industry was still unsatisfactory in the first quarter of 2014.Analysis on operation of printing machine industry.a.Market demand was not strong;sales of product undulated and declined.According to the statistics,the total industrial output value fell by 19.28% in the first quarter of 2014 than the average quarter value in 2013; industrial added value decreased by 4.16%; sales revenue dropped by 22.83%. h. Business operation of enterprises was in poor condition. c. R＆D of new products is an important transformation guarantee for enterprises. d. To take self explore new ways upgrading advantages,and explore new ways.