碳纳米纤维纱的制备及表征

利用自制的静电纺装置制备了PAN纳米纤维纱,然后通过预氧化和碳化工艺得到碳纳米纤维纱,利用SEM、X-衍射和激光拉曼光谱表征了其形貌和结构,并测试了其力学性能。结果表明,经预氧化和碳化得到的碳纳米纤维纱纤维直径和纱线直径均有所减小,但成纱表面仍具有均匀的捻回分布,部分纤维之间有黏结现象并发生断裂。碳纳米纤维纱的分子结构为碳-碳双键连接的网状结构,纤维中存在乱层状的石墨结构。碳化后的纳米纤维纱的断裂强力与断裂伸长率较炭化前的PAN原纱有所降低。     

碳纳米纤维负极材料制备及其电化学性能

为了获得性能优异的碳纳米纤维负极材料并对材料的碳化工艺进行探讨,利用静电纺丝技术和高温碳化制备一维碳纳米纤维负极材料。对获得的碳纳米纤维的形貌、化学成分结构及电化学性能进行测试分析,得到优化的预氧化和碳化条件。结果表明:在预氧化条件为250℃、120 min,碳化条件为800℃、120 min条件下制得的碳纳米纤维具有较好的形貌特征及化学性能,平均直径为190 nm,此时碳结构更加有序,碳含量达到73.7%。通过组装锂离子电池测试电池充放电性能,得到在100 mA/g的电流密度下,放电比容量达到568.4 mAh/g,经过100圈循环后容量保持率达77.3%。     

PAN基碳纳米多孔纤维的制备及吸附性能研究

以聚丙烯腈(PAN)和醋酸锌(Zn(CH3COO)2.2H2O)为溶质,N-N二甲基甲酰胺(DMF)为溶剂,采用静电纺丝法成功制备PAN/醋酸锌纳米纤维毡,并探讨醋酸锌含量(相对于PAN)对纳米纤维毡形貌和直径的影响。对PAN/醋酸锌纳米纤维毡进行预氧化、活化、碳化处理,制备得到碳纳米多孔纤维,并对其得率、孔径分布、比表面积及吸附性能进行研究。实验结果显示:预氧化温度的升高使碳纳米多孔纤维的吸附指标先增后减;在600℃~1 000℃的碳化温度范围内,碳化温度的升高使碳纳米多孔纤维的吸附性能均呈现上升趋势,且在1 000℃时达到最大。     

含铁杂化碳纳米纤维的制备及其在吸附铜离子上的应用

利用PAN与氯化铁的共混溶液进行静电纺丝,经预氧化和碳化得到了掺杂和未掺杂铁的碳纳米纤维。利用SEM和EDS表征了纤维形貌和组成,测试了其力学性能,并研究了杂化碳纳米纤维对Cu~(2+)吸附性能的影响。结果表明,随着纺丝液中铁含量的增加,纤维的平均直径和断裂强度逐渐减小。掺杂铁的碳纳米纤维与未掺杂的碳纳米纤维相比,其对Cu~(2+)的吸附性能显著提高。     

TiO2/PAN碳化纳米纤维膜的制备及其对腐殖酸的降解效果

以丙烯腈为原料自制聚丙烯腈(PAN)粉末,静电纺丝法制备PAN纳米纤维,采用溶胶-凝胶法负载TiO2,制备TiO2/PAN碳化纳米纤维膜.通过SEM、DG-DTG及元素分析等方法对纳米纤维进行表征.研究结果表明,用PAN质量分数为3%的纺丝液进行静电纺丝,在预氧化温度280℃及碳化温度550℃条件下可制得直径100～1...     

静电纺锡/聚丙烯腈纳米纤维膜制备与表征

将纳米锡(Sn)与聚丙烯腈(PAN)共混,采用静电纺丝法制备Sn/PAN纳米纤维膜并进行炭化处理。使用扫描电子显微镜、透射电子显微镜和X射线衍射法对纤维平均直径、直径分布、Sn在纤维上的存在情况以及Sn加入到PAN中静电纺丝后的结晶程度进行表征,将炭化后的纤维膜直接制成锂离子电池负极,测试其电化学性能。结果表明:随着纺丝电压升高或固化距离增大,纤维直径减小;当静电纺丝电压为14 kV,固化距离为14 cm时,纤维平均直径较小,分布最均匀;炭化后纤维变细;Sn加入到PAN中静电纺丝后发生团聚,结晶程度明显下降;Sn/PAN作为锂离子电池负极材料,具有良好的储能性能。     

沥青和PAN的静电纺碳纳米级纤维膜的制备及表征

利用N,N-二甲基甲酰胺(DMF)为溶剂、滚轴为接收装置,通过静电纺丝法制备聚丙烯腈(PAN)和可纺沥青(SP)共混前驱体纳米级纤维膜,再对其进行预氧化和碳化,制备碳纳米级纤维膜,以有效降低碳纤维生产成本.结果 表明:在保持纺丝液质量浓度不变的条件下,纤维直径随SP质量分数的增大而减小.制得的纳米级纤维膜具有一定取向度...     

PANI-DBSA对静电纺PAN纳米纤维直径的影响

在聚丙烯腈（PAN）溶液中加入不同十二烷基苯磺酸（DBSA）掺杂浓度的PANI-DBSA,将此共混体系进行静电纺丝制备纳米纤维。表征两聚合物的相容性,测试了DBSA浓度对对纺丝液导电率的影响,分析DBSA浓度对纳米纤维直径及直径分布的影响。结果表明,PANI-DBSA的氨基与PAN共聚物中的羰基之间存在氢键相互作用,使得聚合物具有良好的相容性,随着DBSA浓度的增加,共混纺丝液的电导率增大,同时纳米纤维的直径逐渐减小,纤维直径的离散度也逐渐减小,在DBSA浓度为1.1mol/L时,纤维的平均直径最小,为116nm。     

聚丙烯腈复合纳米纤维膜的制备及性能表征

采用静电纺丝技术制备口罩芯材,以获得具有纳米蛛网结构的纤维膜材料,从而赋予材料更强的空气滑移效应。采用聚丙烯腈(PAN)和不同质量分数的氯化钡(BaCl₂)制备复合纤维膜。通过电导率和黏度评价纺丝液的性能;通过扫描电镜观察纤维膜的表面形貌,以纤维膜的形貌评价材料的空气过滤效果。结果表明：加入低质量分数BaCl₂对纺丝液的黏度和表面张力的影响较小,而使纺丝液的电导率增大,有利于获得直径分布均匀的纳米纤维膜。采用PAN质量分数为15%的纺丝液,加入质量分数为0.4%的BaCl₂,制得形貌良好的PAN纳米纤维膜。采用直径300～500 nm的电中性NaCl气溶胶颗粒对纤维膜的过滤性能进行测试,结果显示纤维膜的空气过滤效率为87.27%,具有较好的过滤效果。     

溶液喷射纺聚丙烯腈纳米纤维的制备与研究

文章利用溶液喷射纺丝技术,成功制备了聚丙烯腈(PAN)纳米纤维网。通过扫描电镜(SEM)对纳米纤维的形貌观察,探究了纺丝工艺条件对纳米纤维结构的影响规律。结果表明纳米纤维平均直径随着牵伸气流压力增大而先减小后增大,在牵伸气流压力为3.5bar时,平均直径最小,为415.6nm;而牵伸气流温度的提高在一定程度上抑制了气流对溶液细流的牵伸,导致纳米纤维直径变粗。     

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.     

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.     

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.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the