ZnO－Li_2O－V_2O_5系湿敏电阻材料感湿机理研究

借助扫描式电子显微镜发现ＺｎＯ－Ｌｉ２Ｏ－Ｖ２Ｏ５系湿敏材料是由ＬｉＺｎＶＯ４玻璃包裹ＺｎＣｒ２Ｏ４晶粒并相互粘结而成，根据ＬｉＺｎＶＯ４玻璃的形成过程及其微观结构，提出了该系湿敏材料的感湿机理，认为嵌在玻璃相空穴中的Ｌｉ＋和Ｌｉ２Ｏ分别构成了玻璃本体电导和感湿点；由此解释了实测的电阻－湿度特性曲线，并提出可以分别通过调节Ｌｉ＋和Ｌｉ２Ｏ的浓度改变材料的本体电阻和感湿灵敏度．     

表层静电植入与贴伏石墨烯的湿敏聚氨酯纤维制备及其性能

为制备性能优良、环保且适合编织的湿敏纤维,采用表层静电植入法,在静电场中将石墨烯快速植入熔融状态的聚氨酯纤维表层,经快速辊压贴伏制备出类羊毛鳞片状、湿度敏感的聚氨酯湿敏纤维。通过对纤维的制备工艺进行优化,同时对纤维的结构和性能进行分析。结果表明:聚氨酯湿敏纤维的最佳制备工艺为电极板接收距离为15 cm,电压为45 kV,温度为50 ℃,植入时间为15 s;当石墨烯质量分数为4.1%时,湿敏纤维的电导率为7.0 S/m, 断裂强度为94.9 MPa,断裂伸长率91.5%;该湿敏纤维具有良好的湿度敏感稳定性,在高湿环境下具有良好的电阻敏感性,在低湿下具有更短的响应时间(16 s)和恢复时间(26 s);该湿敏纤维在腐蚀性气体环境和柔性智能电子纺织品上具有广泛的应用潜力。     

钛掺杂的α-Fe2O3-K2O系纳米湿敏陶瓷的复阻抗谱

采用硬脂酸凝胶法这种化学新工艺制备了α Fe2 O3 TiO2 K2 O复合氧化物纳米湿敏陶瓷元件 ;研究了该元件在不同湿度下的复阻抗谱 ,并建立相应的模拟等效电路 ;材料晶粒电阻、晶界电阻等特征参数计算结果表明 ,晶粒电阻基本不随湿度变化 ,晶界电阻随湿度升高而降低 .从晶界电阻角度探讨了本系材料的湿敏导电机制 ,低湿阶段导电载流子为电子和自由H ,自由H 以氢桥键过渡态机制迁移 ,中、高湿阶段导电载流子以H3O 为主 .     

ZnCr2O4-V2O5-Li2O-ZnO湿敏材料本体电导成因

研究了ZnCr2O4-V2O5-Li2O-ZnO湿敏材料在干燥状态下的电导类型和在感湿状态下的导电离子类型,对样品在不同湿度下的电子电导和离子电导进行分离测试并与纯水相应量的测试结果作对比,提出该系材料的本体电导只有电子电导,没有离子电导;本体电导所对应的电子电导值取决于晶粒和粒间玻璃相的电导,不因感湿而改变,这为调节相应湿敏元件本体电阻提供了便利.     

添加石墨粉对锐钛矿型TiO_2－V_2O_5系湿敏材料的影响

研究了添加石墨粉、烧结温度及时间对锐铁矿型ＴｉＯ＿２－Ｖ＿２Ｏ＿５系多孔湿敏材料的微结构及湿敏性能等的影响。结果表明：添加石墨粉改善了材料的微结构，提高了湿敏元件的湿度灵敏度和长期稳定性；材料以添加ｗ为５％～１０％的石墨粉，９００℃烧结２ｈ湿敏性能最好。     

溶胶-凝胶法制备的硅掺杂α-Fe2O3-K2O多孔陶瓷的湿敏性能

采用溶胶 凝胶工艺在α Fe2 O3 K2 O复合体系中掺入SiO2 .XRD、BET比表面吸附、Archimede排水法等对α Fe2 O3 K2 O SiO2 陶瓷表征结果表明 ,适量掺杂SiO2 ,材料仍以刚玉结构的α Fe2 O3为主晶相 ,但抑制了主晶相晶粒粗化 ,增大了材料比表面积及孔隙率 .湿敏性能测试发现 ,掺杂摩尔分数 6%的SiO2 ,可获得全湿区范围内阻—湿特性曲线线性关系良好、灵敏度适中、湿滞小、稳定性较高的新型湿敏材料 .其中 ,K 被吸收分散在主晶相晶界硅玻璃相中是改善材料湿滞效应及性能稳定性的主要原因 .     

硼掺杂对α-Fe2O3-K2O湿敏半导体陶瓷结构与性能的影响

用硬脂酸凝胶法工艺合成不同配比的α Fe2 O3 K2 O B2 O3复合氧化物超微粉 ,经液相烧结法制得多孔陶瓷材料 .采用XRD技术、Archimede排水法及压汞法等研究了材料物相、晶粒度及微孔结构 ;电导测试实验表明 ,B2 O3掺杂相可能以非晶态均匀包覆在主晶相晶粒表面及晶界处 ,K 被吸收包埋在B2 O3非晶相中 ;湿敏特性测试结果表明 ,硼掺杂 5% (摩尔分数 )左右 ,全湿区内材料阻 湿特性曲线线性关系良好 ,且感湿灵敏度较高、湿滞小 ,改变掺杂配比 ,可获得不同湿敏转变点的阻 湿特性曲线 ;初步探讨了材料多孔结构与湿敏性能之间的关系 ,得出通过硼掺杂调控材料微结构 ,可明显提高材料湿敏性能稳定性的结论 .     

α-Fe_2O_3-Al_2O_3-Na_2O纳米陶瓷制备及其湿敏特性

采用溶胶－凝胶法制备了α－Ｆｅ２Ｏ３－Ａｌ２Ｏ３－Ｎａ２Ｏ复合超微粉,对微粉及其烧结后的物相及粒度进行了分析。湿敏特性测试结果表明：纳米级α－Ｆｅ２Ｏ３－Ａｌ２Ｏ３－Ｎａ２Ｏ陶瓷元件的感湿灵敏度高于简单氧化物机械混合后制成的α－Ｆｅ２Ｏ３－Ａｌ２Ｏ３－Ｎａ２Ｏ陶瓷元件,并具有较快的响应特性及较好的稳定性。     

北京市亚都环境测控工程公司系列产品介绍

北京市亚都环境测控工程公司是北京亚都企业发展总公司的全资子公司,注册于北京市新技术产业开发试验区,是具有独立法人地位的公司.目前公司拥有50余名科技人员,开发领域涵盖机械、电子、化工、材料、计算机、环境及气象科学诸多学科.主要产品是各种温、湿度传感器、控制器、测量仪表、工业用大型加湿器系列.MS型湿度传感器MS-1型湿度传感器是由湿敏电阻和热敏电阻组成.本品具有灵敏度高,响应速度快等优点.不仅适用于加湿器的自动控制,而且适用于其它设备的湿度测量与控制.MS-2型湿度传感器采用感湿特性优越的湿敏材料浸在具有独特结构的多孔陶瓷基片内,成为具有良好稳定性和耐环境污染能力高的可靠湿敏电阻,并配以高精度的补偿温度用热敏电阻.具有测量精度高,响应速度快,耐环境污染能力强,长期稳定性好等特点,可广泛用于电子、纺织、烟草、环保、食品、仓储、建筑、印刷等行业中的湿度测量与控制.     

北京市亚都环境测控工程公司系列产品介绍

北京市亚都环境测控工程公司是北京亚都企业发展总公司的全资子公司,注册于北京市新技术产业开发试验区,是具有独立法人地位的公司.目前公司拥有50余名科技人员,开发领域涵盖机械、电子、化工、材料、计算机、环境及气象科学诸多学科.主要产品是各种温、湿度传感器、控制器、测量仪表、工业用大型加湿器系列.MS型湿度传感器MS-1 型湿度传感器是由湿敏电阻和热敏电阻组成.本品具有灵敏度高,响应速度快等优点.不仅适用于加湿器的自动控制,而且适用于其它设备的湿度测量与控制.MS-2型湿度传感器采用感湿特性优越的湿敏材料浸在具有独特结构的多孔陶瓷基片内,成为具有良好稳定性和耐环境污染能力高的可     

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