莲子衍生氮掺杂碳的制备及其电催化氧还原反应性能

燃料电池和锌空气电池因具有清洁、高效等优点而被研究者们广泛研究。目前,Pt/C催化剂不耐甲醇且价格高。所以燃料电池和锌空气电池的商业化受到严重限制。来源广和催化ORR活性高的氮掺杂碳材料开始被关注,因此发展氮掺杂碳材料催化剂具有现实意义。通过热解莲子和氯化铵的复合物,制备了氮掺杂碳材料(pNC),并测试了其在碱性溶液中的电催化性能。最重要的是,pNC稳定性和抗甲醇性能均明显优于Pt/C。pNC作为阴极电催化剂所组装的锌空气电池也表现出了优异的电池性能。     

用于敌敌畏高灵敏检测的炭气凝胶@纳米金/离子液体修饰的乙酰胆碱酯酶传感器

在炭气凝胶的基础上制备氮掺杂炭气凝胶并负载金纳米棒，制备了新型的氮掺杂炭气凝胶@金纳米棒纳米复合材料(nitrogen doped carbon aerogel@gold nanorods, N-CA@Au)。以硼掺杂金刚石薄膜电极(boron-doped diamond, BDD)为工作电极，N-CA@Au和1-(4-磺酸)丁基-3-甲基咪唑硫酸氢盐离子液体(1-(4-sulfonic acid) butyl-3-methylimidazole bisulfate ionic liquid,[BSMIM]HSO₄)为修饰材料，制备乙酰胆碱酯酶(acetylcholinesterase, AChE)传感器AChE/N-CA@Au-[BSMIM]HSO₄/BDD对蔬菜中的敌敌畏进行定量分析。研究发现，N-CA@Au具有良好的导电性和吸附特性，[BSMIM]HSO₄可以为AChE/N-CA@Au-[BSMIM]HSO₄/BDD提供稳定的电化学反应环境，使AChE、N-CA@Au和BDD发挥良好的协同作用...     

“新型柔性锌”空气电池可编织可穿戴

正将电池制作成能弯曲、易携带的配饰,甚至编入纤维制成衣服,是否会成真?天津大学胡文彬教授、钟澄教授、邓意达教授课题组通过一种快速、简单、连续的方法制备出一种可编织的柔性线状锌一空电池;此外还设计制备了一种具有高效氧还原与氧析出催化性能的原子级厚度的介孔Co3O4/N-rGO(介孔四氧化三钴/氮掺杂氧化还原石墨烯)复合纳米片,以该复合纳米片作为催化剂的柔性线状锌一     

基于三维石墨烯的甘油酶生物燃料电池的构建及其性能研究

本文采用修正的Hurnmers方法制备了氧化石墨,通过超声波剥离得到氧化石墨烯溶液,用水热法进行还原,制得三维石墨烯。结果表明,制备的三维石墨烯材料具有多孔结构,且还原后某些含氧基团消失。所构建的酶生物燃料电池以三维石墨烯(GN)为载体,以麦尔多拉蓝(MB)为导电介体,用Nafion(NF)固定甘油激酶(GK)和甘油-3-磷酸氧化酶(GPO)制备阳极催化电极,并以Pt/C作为阴极催化剂。结果显示,基于NF/GN/MB酶修饰碳纸电极的甘油酶生物燃料电池具有良好的放电性能,开路电位达到0.77 V,并在0.42 V取得最大功率密度42.05 μW/cm2。论文中对该酶生物燃料电池的组装、工作条件等进行了优化,用极化曲线法和交流阻抗法对其性能进行了评价。该酶生物燃料电池将为生物柴油副产物甘油的处理,提供一种清洁可靠的能源再利用方式。     

氨基酸基氮掺杂荧光碳点的制备及饮料中Hg2+的检测

汞离子是一种高毒性的重金属污染物,人体摄入后会带来健康危害,因此控制食品中的汞离子含量非常重要。以柠檬酸为碳源,不同的氨基酸为氮源掺杂,采用一步水热法制备高性能荧光的碳点(CDs),探究不同氨基酸基氮掺杂对碳点荧光量子产率(QY)的影响,以及这些氨基酸基氮掺杂碳点对汞离子的响应。结果显示,不同氨基酸的碳链长度和官能团对CDs的QY有一定的影响。Hg2+能高效猝灭以甘氨酸(Gly)为氮源掺杂的Gly-CDs的荧光,Gly-CDs具有良好的荧光稳定性,在优化的试验条件下,用于Hg2+检测的线性范围为0.00~7.00 μmol/L和8.00~60.00 μmol/L,检出限为0.20 μmol/L。据此构建的荧光探针用于检测实际饮料样品中的Hg2+,回收率在90.08%~107.90%。该方法简便、快速、灵敏、适用于饮料中Hg2+的测定。     

MnO2纳米片功能化修饰的氮掺杂碳纤维电化学性能研究

以细菌纤维素(BC)为模板原位生长聚吡咯,再将其高温碳化以得到高导电性能的氮掺杂碳纤维(NCF),通过水热反应将MnO₂纳米片修饰到NCF表面,形成核壳结构的MnO₂纳米片包裹氮掺杂碳纤维(NCF/MnO),并对其进行理化分析。结果表明,相对₂于纯δ-MnO₂,NCF/MnO₂具有更优异的电化学性能,在1 A/g的电流密度下,其比电容达到193.2 F/g;在10 A/g的电流密度下进行10000次恒流充放电后,其比电容保持率为107%,具有优异的循环稳定性;NCF的引入能极大提高MnO₂电化学性能,为MnO₂电极材料的发展提供理论依据。     

基于ZnCo2O4的多孔碳纳米纤维制备及其储能性能

针对锂硫电池循环过程中容量衰减快的问题,采用水热法制备ZnCo₂O₄纳米颗粒,然后与聚丙烯腈(PAN)混合,通过静电纺丝法制备复合纳米纤维并进行炭化处理得到复合多孔碳纳米纤维。借助扫描电子显微镜、透射电子显微镜、X射线光电子能谱仪、拉曼光谱仪、比表面积测试仪表征复合多孔碳纳米纤维的微观结构和物化性能,优化得到最佳制备工艺;并将其作为正极硫载体测试电化学性能。结果表明:基于ZnCo₂O₄制备的复合多孔碳纳米纤维存在大量孔孔相连的通道,比表面积高达210.85 m²/g;组装成的锂硫电池具有典型的充放电平台以及明显的氧化还原峰,其初始放电比容量为759.2 mA·h/g,50圈充放电循环后,仍具有74.0%的可逆比容量,相比于不掺杂ZnCo₂O₄的静电纺丝碳纳米纤维具有更高的比容量,更好的倍率性能。     

ZnCl2络合法分离黑液木质素高效制备高吸附性能活性炭

采用ZnCl₂络合的方式从黑液中分离出木质素并获得木质素-锌络合物,将其作为前驱体,经碳化高效制备高吸附性能活性炭(CAC)。结果表明,经ZnCl₂络合(0.5 mol/L ZnCl₂,0.6 mL/mL黑液)后,黑液中分离出89.5%的木质素,络合处理后黑液的CODCr值降低72.4%,pH值呈中性。同时,金属络合作用使得锌离子均匀分布在木质素-锌络合物中,有助于碳化过程中多孔结构的均匀分布。与传统酸析木质素浸渍工艺相比,木质素-锌络合物碳化法制备的活性炭具有更高的比表面积和吸附量。所制备的CAC活性炭对阳离子亚甲基蓝和阴离子甲基橙的最大平衡吸附量分别为1046.8和263.6 mg/g,优于大多数研究报道制备的吸附剂的吸附量。     

有机肥C/N优化下氮肥运筹对烟株根际无机氮和酶活性的影响

大田条件下研究了基于有机肥C/N优化下不同氮肥用量和基追比对烤烟根际土壤无机氮、碳氮转化及酶活性的影响。结果表明:(1)低、中氮(48.0、108.0 kg/hm²)条件下,根际NH₄⁺-N含量随生育期延长而降低;高氮(168.0 kg/hm²)条件下,根际NH₄⁺-N含量在团棵期至旺长期增加,随后降低;不同处理根际硝态氮含量均随着生育期的延长而降低;(2)土壤微生物量碳随生育期的延长和施氮量的增加而增加;(3)土壤脲酶和转化酶活性均随施氮水平增加而增强,低氮和中氮条件下脲酶活性在成熟期时略微下降,而高氮条件下土壤脲酶活性在整个生育期持续增加。低氮基追比(5:5)处理的土壤转化酶活性在团棵期后高于中高氮基追比处理。高氮水平因施氮量过大促使土壤有效氮持续供应,致使成熟期不能及时"氮素调亏",降低烟叶品质;而中氮水平各处理的土壤脲酶活性呈先增加后降低趋势,并以氮肥适当后移,基追比(5:5)时烟株"旺长-现蕾"阶段土壤酶活性较高,与该阶段烟株氮素需求规律相吻合。     

Li掺杂CeO2固体碱催化甘油酯交换合成碳酸甘油酯

针对由甘油制备碳酸甘油酯的酯交换法中催化剂制备方法复杂、活性组分易流失等问题,采用一锅法制备了Li掺杂CeO₂固体碱催化剂。对催化剂进行了X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、BET、X射线光电子能谱(XPS)、CO₂程序升温脱附(CO₂-TPD)等表征。以甘油转化率和碳酸甘油酯产率为指标,对催化剂进行了筛选,并采用单因素实验对甘油酯交换合成碳酸甘油酯的工艺条件进行了优化,同时考察了催化剂的重复使用性能。结果表明：Li与CeO₂之间能够产生协同作用,Li的掺杂能够明显增加CeO₂的中强碱活性位点;Li、Ce与柠檬酸物质的量比为0.3∶1∶1时,催化剂催化活性最好;甘油酯交换合成碳酸甘油酯的最优反应条件为反应温度100℃、反应时间2.0 h、催化剂用量为甘油质量的1%、甘油与碳酸二甲酯物质的量比1∶2,在此条件下甘油转化率为90.16%,碳酸甘油酯收率为90.04%;催化剂在重复使用5次后活性无明显下降。采用一锅法制备的Li掺杂CeO₂     

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.     

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.     

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.     

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.