深冷处理温度对锡锑/碳纳米纤维负极材料锂电性能的影响

为提高锡锑/碳(SnSb/C)纳米纤维作为负极材料的锂电池的循环使用性能,利用深冷处理对SnSb/C纳米纤维进行形貌再造,比较不同深冷温度处理前后纳米纤维的形貌变化,并测试其含碳量和比表面积,通过分析电池的恒流充放电曲线研究深冷处理温度的变化对其电化学性能的影响。结果表明:当深冷处理温度为 -100 ℃时,SnSb/C纳米纤维表面粗糙度增加并出现沟壑;深冷处理加快了聚丙烯腈的预氧化反应速度,使其分解温度提前,含碳量高达75.4%,比表面积为214.0 m²/g;锂电循环过程中,因深冷处理对其形貌结构的影响,电池容量呈持续上升趋势,循环120圈后容量保持率为123.5%。     

纳米纤维锂电池负极材料的制备及性能分析

探讨一种用于高性能锂离子电池负极材料的制备及性能。通过配制乙酰丙酮铁的聚丙烯腈/聚甲基丙烯酸甲酯(PAN/PMMA)混合溶液用作前驱液,利用静电纺丝技术制备多孔碳/四氧化三铁纳米纤维。结果表明:多孔碳/四氧化三铁纳米纤维呈现多孔的结构和凹凸不平的形貌,Fe_3O_4纳米粒子均匀地镶嵌在碳基质中;在电流密度为100 mA/g时,多孔碳/四氧化三铁材料电极首次放电比容量高达1 380 mAh/g,经过100次循环后,稳定比容量为641 mAh/g;这种电极材料表现出优良的倍率性能,在电流密度为5 000 mA/g时,其可逆比容量仍维持在330 mAh/g。认为:这种多孔碳/四氧化三铁复合物作为高性能锂电池负极材料具有广泛的应用前景。     

皮芯结构Sn/C包覆碳杂化纳米纤维的制备及其在锂离子负极材料中的应用

用同轴静电纺丝技术成功制备了以碳作为纤维骨架,锡在碳中随机分布并包覆在碳外层的皮芯结构纳米纤维。利用经典静电纺丝纤维直径预测理论,通过调整皮芯层纺丝速度比制备了不同比例皮芯纤维直径的纳米纤维,并将其应用于锂离子负极材料中。采用投射电子显微镜观察了皮芯结构的纤维形貌;利用X射线衍射仪表证了纤维的晶型结构,特别分析了该材料的电化学性能。结果表明:通过纺丝速度比的调节成功获得了不同直径比的皮芯结构纤维;当碳化温度达到800℃时,形成了锡、无定形碳共存的晶型结构;特别是使用纺丝速度比为1∶1时,锂离子电池的循环稳定性最好,循环50圈后,容量保持率达到69%。     

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。     

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。     

碳包覆锡锑合金纳米纤维的制备及应用

以氧化锡锑纳米颗粒(Sn0.92Sb0.08O2.04)为前驱体,葡萄糖为碳源,用水热合成法制备碳包覆锡锑合金,然后采用静电纺丝技术制备碳包覆Sn Sb/C纳米纤维。应用透射电子显微镜、扫描电子显微镜对碳包覆锡锑合金纳米颗粒及纤维的形貌进行表征,利用X射线衍射仪分析了碳包覆锡锑合金混合纳米纤维的晶型结构。研究了碳包覆Sn Sb/C纳米纤维作为一种高容量锂离子电池负极材料的电化学性能。结果表明,成功制备了碳包覆锡锑合金纳米纤维;随着纳米纤维中碳包覆锡锑合金含量的增加,制备的负极材料具有较高的可逆容量及较好的循环性能。     

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。     

全木质素衍生硬碳电极的制备及储钠性能研究

钠离子电容器结合了电池型负极的高能量密度和电容型正极的高功率密度,成为新一代储能器件,硬碳材料作为电池型负极,是当前的研究热点。本研究以制浆黑液为原料,通过提纯、预碳化和高温热解碳化制备木质素衍生硬碳材料,分析其石墨层间距、微晶结构等性质随碳化温度变化的规律,研究了木质素衍生硬碳电极的电化学性能及储钠机理。研究结果表明,随着碳化温度从800 ℃升高至1600 ℃,木质素衍生硬碳材料的石墨层间距从0.406 nm减小至0.378 nm,赝石墨层比例从52.69%升高至77.60%。此外,在木质素衍生硬碳电极充放电过程中,更多的Na⁺在石墨层间嵌入和脱嵌,电极的平台容量从56.8 mAh/g提高至236.0 mAh/g;在斜坡容量变化不大的情况下,平台容量的大幅增加使木质素衍生硬碳电极的可逆容量高达333.7 mAh/g。根据恒电流间歇滴定技术（GITT）分析可知,Na⁺在木质素衍生硬碳电极中的存储机制符合“吸附-嵌入/填充”模型。     

锡/碳纳米纤维负极材料的结构变化对其锂电电化学性能的影响

为提高锡基负极材料的锂电性能,分别使用深冷处理作为热补偿方式以及同轴静电纺丝技术成功构建了具有皮芯结构的锡/碳纳米纤维。从形貌和结构方面分析了不同构建方式对皮芯结构锡/碳纳米纤维的影响,并进行锂电性能分析。结果表明:不同构建方式形成了碳层厚度各异的皮芯结构,并且发现使用同轴静电纺丝获得的锡/碳纳米纤维中存在锡与二氧化锡晶型结构共存的现象。依据纳米纤维的制孔原理,获得了深冷处理的锡/碳纳米纤维表现出优异的孔隙结构(BET为89.3 m~2/g)及79%的锂电容量保持率(50圈)的作用机理。     

锡/碳纳米纤维锂电负极材料形貌结构再造及其机制

为改善锡/碳(Sn/C)纳米纤维形貌结构并使其获得优异的锂电性能,采用醋酸锡为前驱体,聚丙烯腈为碳源,通过静电纺丝技术制备了Sn/C前驱体纳米纤维,并通过不同顺序的炭化工艺和深冷处理工艺对Sn/C前驱体纳米纤维进行形貌再造,制备了具有多孔结构与皮芯结构的Sn/C纳米纤维,最后通过形貌表征、比表面积以及晶型结构测试了纳米纤维的结构和性能。结果表明:Sn/C纳米纤维的多孔和特殊形貌的碳包覆结构,有效防止了Sn颗粒的团聚,缓解了充放电时电极材料的体积膨胀,同时减少了容量损失,增强了电极材料的导电性和结构稳定性;经过先深冷处理再炭化处理,具有多孔结构的Sn/C纳米纤维表现出最稳定的电化学性能,循环100圈后的质量比容量保持率高达93.9%。     

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.     

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     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press