当前我国食品添加剂的现状及监管建议

近年来,随着经济发展及生活水平的提高,食品安全问题越来越受到广泛关注。而食品安全问题中,有关食品添加剂的安全这几年更是颇受关注,许多是由于添加工业产品而被人们误认为食品添加剂,我们应该正确认识食品添加剂。本文分析了当前我国食品添加剂使用中存在的问题,并对食品添加剂的安全监管提出相关建议。     

新疆传统发酵乳制品及酵头中酵母菌的分离鉴定

研究了新疆传统发酵食品中的酵母菌菌群结构及其遗传多样性。采用YPD富集培养后稀释涂布的方法,从12个地区161份样品中分离得到472株酵母菌,通过YPD菌落形态、WL营养培养基聚类分析为16类,挑选不同表型的代表菌株11株进行5.8S-ITS区和26S D1/D2区测序,通过国际核酸数据库分析鉴定菌种。从分离到的472株酵母菌中,共鉴定出6个属8个种,其中包括263株Saccharomyces cerevisiae,156株Issatchenkia orientalis,10株Torulaspora delbrueckii,9株Pichia fermentans,21株Saccharomyces unisporus,7株Metschnikowia pulcherrima,4株Pichia membranifaciens,2株Clavispora lusitaniae,地区优势菌东方伊萨酵母和酿酒酵母。不同基物与不同地区的菌群结构明显不同。上述结果表明新疆的酵母资源具有丰富多样,本研究初次全面地对新疆传统食品的酵母菌群落结构进行分析,为新疆传统食品微生物资源的开发利用,与传统食品的质量控制等奠定了基础。     

A new dual driver planar eddy current probe with dynamically controlled induction pattern

A new planar eddy current probe design is presented. This new concept is capable of dynamically modify the induced eddy currents pattern in accordance with the operational non-destructive testing parameters. The probe is composed by two orthogonally positioned driver traces and a set of sensing coils on each quadrant between the traces. Eddy currents result from the magnetic field contribution of the two driver traces and can be modified by changing the relative amplitude and phase of the currents flowing in the driver traces. Finite Element Modeling was used to simulate the eddy currents patterns and to predict the probe response to defects with different orientations. Experimental validation was carried using a prototype of the probe and artificial defects showing very good agreement with the Finite Element Modeling.     

A system for the automatic generation of solid models of woven structures

Visualisation of complex 3D textile structures used to reinforce advanced composite materials can be extremely difficult. 3D models to assist in visualisation are recognised as being very helpful. In addition they can be used as the basis for parametric studies and finite element analysis, although the latter downstream use puts considerable demands upon the solid model.This paper describes a novel technique to automatically generate a parametric solid model of a woven textile reinforced composite material. The solid model is generated using a program file written in I-deas^® Open Language. The input data, provided by the user, describes the cross-sectional shape of tows. The system uses this data to automatically generate a set of basic tow ‘parts’. It then proceeds to put these together in a fabric assembly with appropriate constraints assuring the correct relative positions of the interlacing yarns.This assembly model of the tows constitutes the representative volume element, RVE, of the fabric structure. To demonstrate the principle, the approach is applied to the modelling of a 2D plain weave structure.     

MCM-41 supported nano-sized CuO-CeO_2 for catalytic combustion of chlorobenzene

In this paper,MCM-41 was synthesized by a soft template technique and MCM-41 supported CuO-CeO_2 nano-sized catalysts with different Cu/Ce molar ratios were prepared by a deposition-precipitation method.N_2 adsorption,HRTEM-EDS,H_2-TPR,XPS characterization,as well as catalytic activity and durability tests for the catalytic combustion of chlorobenzene(CB) were conducted to explore the relationship between the structure and catalytic performance of the catalysts.It is revealed that cuCe(6:1)/MCM-41 has the highest activity and can completely catalyze the degradation of CB at 260℃.The reasons for the high activity of the catalysts are as follows:MCM-41,a type of mesoporous material which has large pore size and large specific surface area,is suitable as a catalyst carrier.The average diameter of nano-sized CuO and CeO_2 particles is about 3-5 nm and adding CeO_2 improves the dispersion of active component CuO,which are highly and evenly dispersed on the surface of MCM-41.Characterization results also explain why MCM-41 supported CuO-CeO_2 with appropriate proportion can highly enhance the catalytic activity.The reason is that CeO_2 acting as an oxygen-rich material can improve the mobility of oxygen species through continuous redox between Ce~(4+)and Ce~(3+),and improve the catalytic performance of CuO for CB combustion.Besides,CuCe(6:1)/MCM-41 also displays good durability for CB combustion,both in the humid condition and in the presence of benzene,making it a promising catalytic material for the elimination of chlorinated VOCs.