富硒食品标签标准研究

首次系统研究了湖北省地方标准———富硒食品标签,并经湖北省质量技术监督局批准、发布、实施。为规范硒产品生产和销售,保证硒产品质量和营养保健效果,使硒资源开发利用走上标准化、科学化轨道和制定国家标准提供了依据。     

富硒产品相关标准的技术动态分析

该文对国内外富硒相关标准进行了梳理,从标准中硒的检测技术发展、不同方法间的异同,以及每一种检测原理的灵敏度、准确度和精密度等方面对硒的检测方法标准进行了动态追踪和系统分析,同时对富硒产品标准中覆盖的产品范围、不同产品的硒含量要求和其他主要技术要素进行了比较归纳,最后结合我国富硒产业的发展实际提出了硒形态分析检测的必要性和制定相关检测方法标准,以及在产品标准中增加硒形态要求技术要素的合理化建议,这对规范我国富硒产品的检测和富硒产品标准的科学化制定具有重要的指导和借鉴意义。     

兰州制定富硒农业产业标准

兰州处于富硒带,在发展现代农业的进程中,重点开发了名特优富硒农产品。该市以提高产品质量为目标,通过加快标准及生产技术规范制定、严格农业投入品管理、建立健全质量监测检验体系、实行市场准入和产地准出、建立产品追溯制度等措施,加强富硒农产品质量标准化建设。     

HG-AFS测定富硒水果中的硒量

对氢化物发生原子荧光法检测水果中的微量硒的方法进行了研究,确定了样品最佳实验条件。实验表明：在最佳实验条件下,硒的检出限为0．20μg／L．回收率为96．9％～101％。该方法的灵敏度、精密度和准确度较高,可满足一般（富硒）水果中硒的检测要求。     

丰城富硒大米

近日，国家质检总局正式批准丰城富硒大米成为国家地理标志保护产品，产地范围为丰城市董家镇、湖塘乡、梅林镇、尚庄街道、桥东镇、荷湖乡、丽村镇、铁路镇、洛市镇、秀市镇、泉港镇11个乡镇街道现辖行政区域。据了解，丰城市富硒土壤面积达524．7平方公里。所产丰城富硒大米以其米粒细长、晶莹剔透、口感佳、硒元素丰富等特点。     

浅析富硒水稻品种的选育及栽培技术

硒是人体必须的微量元素，与人体健康有密切关系，具有多种重要的生理功能。大米是人们日常生活的重要主食，富硒功能米产品具有广泛的应用前景。将富硒功能水稻综合配套栽培技术进行分析。     

纳米技术的安全应用——富硒纳米茶安全应用的研究

纳米科技由于其广阔的应用前景,近几年得到了快速的发展,同时它也存在着很多未知因素及不确定因素,所以,为了使纳米科技真正造福人类,对纳米技术的安全应用的研究就极为重要。     

富硒功能农业标准化现状分析与思考

发展富硒功能农业是促进农业供给侧结构调整和实施乡村振兴战略的有效路径。然而,目前我国富硒功能农业产业还存在诸多不足,如产业规模较小、生产经营不规范、产品质量良莠不齐等。标准化作为规范产业发展、提升产品竞争力的重要手段,在富硒功能农业领域的应用亟待加强。本文研究分析了富硒功能农业标准化现状,针对目前存在的问题提出了对策和建议,以期为富硒功能农业标准化工作提供参考和借鉴。     

基于石台县富硒产业标准化生产的案例分析

标准化是促进科技成果转化为生产力的有效途径,是提升产品质量安全水平,增强产品市场竞争力的重要保证。本文以石台县富硒产业为研究对象,采用实践操作与案例分析的方法对富硒产业标准化生产的具体做法、主要成效做出了相关论述。旨在运用标准化理论和方法探索适用于石台县富硒产业发展路径的同时,为全国富硒产业标准化发展提供一些思路,以期实现富硒产业高质量发展,促进产业增效、群众增收。     

Speciation of selenium in groundwater: seasonal variations and redox transformations

Speciation of selenium in groundwater is essential from the viewpoint of toxicity to organisms and biogeochemical cycling. Selenium speciation in groundwater is controlled by aquifer redox conditions, microbial transformations, dissolved oxygen (DO) and other redox couples. A suburban area of Chennai city in India, where improper waste disposal measures have been practiced is selected for this study. Se(IV), Se(VI) and other hydrochemical parameters were monitored in shallow ground water during pre- and post-monsoon seasons for a period of three years. The objective of the study was to investigate the effect of groundwater recharge on selenium speciation. The concentration of Se(IV), and Se(VI) ranged between 0.15-0.43 μg L⁻¹ and 0.16-4.73 μg L⁻¹, respectively. During post-monsoon period the concentration of Se(IV), and Se(VI) ranged between 0.15-1.25 μg L⁻¹ and 0.58-10.37 μg L⁻¹, respectively. Se(VI) was the dominant species of selenium during the pre- and post-monsoon periods. During the post-monsoon periods, leaching of selenium from soil was more effective due to the increased oxidizing nature of the groundwater as indicated by the DO and redox potential (Eh) measurements. This finding has important implications on the behavior of selenium in groundwater, and also on the health of people consuming groundwater from seleniferous areas.     

Synthesis and stabilization of selenium nanoparticles on cellulose nanocrystal

Selenium nanoparticles of 10-20 nm in diameter have been prepared using cellulose nanocrystal (CNXL) as a reducing and structure-directing agent under hydrothermal conditions. Na₂SeO₃ was reduced to form elemental selenium nanoparticles under hydrothermal conditions. During the hydrothermal process (120-160 °C), CNXL rods were mainly maintained and selenium nanoparticles were interfacially bound to the CNXL surface. The reaction temperature affects the sizes of interfacially bound selenium nanoparticles. X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), and transmission electron microscope (TEM) were employed to characterize interfacially bound selenium nanoparticles on CNXL surface.     

A limit load solution for highly weld strength undermatched DE(T) specimens

A new upper bound solution for highly undermatched welded DE(T) specimens is proposed. A distinguished feature of this solution is that it accounts for the thickness of the specimen. Even though this case is more general than plane-strain and plane-stress solutions, the final result is given in terms of ordinary and double integrals. Comparison with a plane strain solution shows that the thickness of the specimen has a great effect of the limit load.     

Synthesis of selenium nanoparticles in the presence of silk fibroin

This paper describes a solution-phase approach to the synthesis of selenium nanoparticles by reducing selenious acid solution with ascorbic acid in the presence of silk fibroin. The monodispersed spherical selenium colloid particles obtained were very stable in silk fibroin solution and characterized by Atomic force microscopy and X-ray techniques. The influences of temperature and ultrasonication on the morphology of selenium nanoparticles were also discussed. The experiments showed that the selenium nanoparticles with various morphologies could be obtained under different temperatures and the appropriate ultrasonication time was 60 min. This result indicated that the silk fibroin molecules intimately associated with the surface of the selenium particles and controlled the growth particles.     

Effect of plastic anisotropy on the limit load of highly undermatched welded specimens in bending

Plastic anisotropy is a typical property of many metals and it can have a significant effect of the limit load of structures. It is therefore of importance to evaluate this effect for typical geometries covered by compendia of flaw assessment procedures for limit load solutions. The present paper deals with a typical highly undermatched specimen in pure bending. It is assumed that the mismatch factor (the ratio of the yield stress of weld material to the yield stress of base material) is so small that plastic deformation solely occurs in the weld whereas the base material is elastic (rigid). The weld material obeys Hill’s quadratic orthotropic yield criterion. The variation of the upper bound bending moment with the thickness of the weld and anisotropic properties of the material is illustrated. Comparison with the isotropic case made shows that an effect of plastic anisotropy can be quite large.     

APDC和MIBK萃取富集石墨炉原子吸收法测定天然水、废水中的硒

本文研究了天然水及废水中痕量硒的石墨炉原子吸收测定方法。天然水、废水等经硝酸—高氯酸进一步消化后,用APDC和MIBK萃取富集,用原子吸收石墨炉法测定。检出限0.7μg·L~(-1)。结果令人满意。     

A limit load solution for a highly weld strength undermatched tensile panel with an arbitrary crack

A new plane strain upper bound solution for highly undermatched welded tensile panels with a crack is proposed. A distinguished feature of this solution is that the crack is arbitrarily located within the weld and its shape is also arbitrary, though some restrictions do apply. The latter are explained in detail such that the class of structures for which the solution is applicable is precisely specified. The solution is given in a very simple closed form.     

Inorganic selenium speciation in groundwaters by solid phase extraction on Dowex 1X2

A Dowex 1X2 resin separation technique followed by analysis with atomic absorption spectroscopy was evaluated for the study of inorganic selenium speciation in groundwaters. After Se(IV) and Se(VI) were retained on the resin column, Se(IV) and Se(VI) were eluted out by 0.1 and 1M nitric acid solutions. The method detection limit was 5.6 ng/L for both Se(IV) and Se(VI). Analysis of synthetic solutions consistently yielded more than 90% recovery of these two selenium forms with negligible cross-contamination. The results of spiked well waters show that this method can be applied at ultra-trace level of Se in groundwater and the interference of chloride ion can be neglected. Water samples collected from the monitoring wells in the Science-based Industrial Park, Hsin-Chu, Taiwan, were analyzed. Average dissolved selenium concentrations were 32.1+/-17.6 ng/L. The proportion of Se(VI) to the total dissolved selenium ranged from 47.6 to 61.2% and an average of 53.8% in water samples analyzed.     

Study on the limit cycle oscillation of the drum brake non-linear vibration model at low frequency

A 5-degree non-linear dynamic model is presented to describe the low frequency vibration of drum brake. The centre manifold theory is applied to reduce the system at the Hopf bifurcation point. Through the calculation of normal form of the reduced system at the Hopf bifurcation point, the limit cycle oscillations (LCOs) amplitude is obtained. By this method, the effect of the drum brake parameter on LCO amplitude is studied, the law of the LCOs amplitude varying with systematic parameters is obtained.     

室内挥发性有害有机物限量标准研究

室内挥发性有害有机物的种类繁多，我国现有室内空气质量标准中有机物的限量指标只有甲醛、苯、甲苯、二甲苯、TVOC5种。我们通过研究发现室内空气中17种有机挥发性有害物质出现的频率较高，浓度较大，且对人体健康有很大的危害，世界各国和各地区的空气质量标准分别对这17种物质中的部分组分给出了安全限量。通过科学分析我们建议了涵盖甲醛、烷烃类、卤代烃类、苯系物等的室内挥发性有害有机物限量标准，使我国的室内空气质量控制指标更具有效性和针对性。