蒸馏酒中甲醇和铅含量检测能力验证研究

目的评价国内酒类检测机构对蒸馏酒中甲醇和铅含量的检测能力。方法制备含甲醇和铅的蒸馏酒的样品,用单因子方差分析和t检验法进行均匀性与稳定性检验,采用Z比分数对最终的测试结果进行评定。结果共有199家单位参加甲醇检测,其中182家取得满意结果,满意率为91.5%。有212家单位参加铅检测,其中202家取得满意结果,满意率为95.3%。结论国内的酒类检测机构的甲醇和铅的检测能力水平总体比较好。     

Convergence analysis of distributed fixed‐step power control algorithm for cellular mobile systems

Power control plays a vital role in the operation of cellular systems. It has been shown that a power control mechanism with distributed fixed‐step control algorithm using a single bit can maintain the received carrier‐to‐interference ratio (CIR) within a desired range in long‐term fading channels. However, as far as the short‐term fading is concerned, whether such a power control algorithm remains convergent is not clear. In this work, a simple received CIR model is adopted to derive the condition that ensures system stability for short‐term fading channels. The bounds of the received CIR are also obtained. Furthermore, the effects of the power control step size and the time required for convergence are also analyzed. Copyright © 2007 John Wiley & Sons, Ltd.     

Dioscorea improves the morphometric and mechanical properties of bone in ovariectomised rats

BACKGROUND: The aim of this work was to determine the effects of oral administration of dioscorea on the morphometric and mechanical properties of the femur in ovariectomised (OVX) rats. Female Wistar rats that had undergone surgery for ovariectomy were used as a model of menopause and osteoporosis. Four weeks after surgery the animals were given oral dioscorea (0, 250, 750 or 1500 mg kg^?1 day^?1) for 27 days, then the porosity, mineral fraction, stiffness and toughness of the femur and the ultimate force needed to break the femur were measured. RESULTS: Ovariectomy resulted in an increase in the total volume, dry weight and porosity but a decrease in the mineral fraction of femora. Subsequent chronic administration of dioscorea reversed the effect on porosity and increased the ultimate force of the femur in OVX rats but did not affect the bone properties of sham‐operated rats. CONCLUSION: These results suggest that chronic administration of dioscorea may enhance bone strength and provide insight into the role of dioscorea in bone remodeling and osteoporosis during the menopause. However, the benefit is not clear for the reproductive female. Copyright © 2008 Society of Chemical Industry     

干海参等级规格国家标准解读

干海参是近年来颇受人们喜爱的一种高营养、耐贮存的食品。为有效规范干海参产品的生产,保障产品质量,促进产品的优质优价,2017年11月1日国家质量监督检验检疫总局、国家标准化管理委员会颁布了GB/T 34747-2017《干海参等级规格》国家标准,自2018年5月1日起正式实施。本研究在介绍GB/T34747-2017基本框架的基础上,阐述了水分、盐分和水溶性总糖等主要技术指标和质量分级的确立依据,可为企业和检测部门正确理解和运用GB/T 34747-2017提供参考。     

海参加工工艺、营养成分及活性物质研究进展

海参是著名名贵药材和滋补营养品,随着人工养殖业的发展,海参的产量和消费量也在逐年上升,而其营养价值和活性物质的生理功效也成为诸多研究者关注的重点。本文通过对海参的产品形式、加工工艺、营养价值,海参多糖提取检测方法 ,海参皂苷分离纯化方法以及海参中众多活性物质所具有的生理功效进行综述,总结了目前海参中活性物质的检测方法缺少统一的标准,所研究的活性物质种类较少,部分活性物质的活性机制尚不明确的研究现状,并对海参作为营养品的发展前景提出了展望。     

凝析气藏氟碳气湿反转剂FC-1的室内研究

本文采用核壳乳液聚合法制备了一种氟碳气湿反转剂FC-1,采用红外光谱表征了共聚物的结构,对FC-1处理前后岩心的接触角、表面能谱、扫描电镜和透射电镜等表征。结果表明:FC-1为含氟丙烯酸酯共聚物。FC-1对岩石有良好的气湿反转能力,处理后的岩心表面由强亲液转变为疏油疏水的中性气湿。经10%FC-1溶液处理并经100℃热处理12 h后的岩心,蒸馏水在其表面的接触角最高可达124.98°,正十六烷在其表面的接触角可达84.69°,表面能降低至8.33 mJ/m2。     

Tri-Diagonal Preconditioner for Toeplitz Systems from Finance

We consider a nonsymmetric Toeplitz system which arises in the discretization of a partial integro-differential equation in option pricing problems. The preconditioned conjugate gradient method with a tri-diagonal preconditioner is used to solve this system. Theoretical analysis shows that under certain conditions the tri-diagonal preconditioner leads to a superlinear convergence rate. Numerical results exemplify our theoretical analysis.     

Pinning Effects in Nb Thin Films with Artificial Pinning Arrays

We summarize some results on the behavior of vortex dynamics and pinning effects in superconducting films with artificial pinning centers. Superconducting thin films with regular arrays of holes were fabricated using electron-beam lithography and reactive dry etching techniques. Vortex dynamics in the mixed state in type II superconductors is strongly influenced by the presence of defects, which act as pinning centers. Periodic critical current matching peaks were observed in magnetotransport measurements. The matching effect is caused by the interplay between the pinning centers and vortex lattice. Therefore, vortex lattice behaviors are changed for different temperatures and the geometry of the pinning centers. Molecular dynamic simulations are made to study this phenomenon. The ground state distribution of vortices obtained from simulations can give a reasonable explanation of the prominent matching peaks we found in the experiments.     

Production,health implications and applications of oleogels as fat replacer in food system: A review

Various food formulations widely utilized solid fats to provide specific textural properties and sensory attributes. Partially hydrogenated oil was commonly used as solid fat before being banned by FDA recently because of the existence of trans fats. Oleogels, semi-solid gel typically prepared from liquid vegetable oil and food-grade oleogelators, is developed as an alternative for solid fats that is free of trans fat and low in saturated fats. Oleogels are prepared via indirect or direct oleogelation technology by which the liquid oil is entrapped in a three-dimensional network with the aid of low molecular weight oleogelators (LMOGs) and high molecular weight oleogelators (HMOGs). Oleogels received tremendous attention from food scientists to be used in various food applications, particularly high-fat products such as comminuted meat, chocolates, ice cream, shortening and margarine and even as a deep-frying medium. They satisfy not only the current trends of consumers for healthy food products (free of trans fat and low in saturated fat) but also provide viscoelastic solid- and gel- like properties to structure high fat food products. More importantly, recent studies showed that oleogels tend to be metabolized differently from conventional fats and oils giving them an additional advantage in improving the nutritional value of high-fat foods. Therefore, this review aims to provide an overview that captures the latest studies on oleogels from their production via direct dispersion and indirect dispersion methods, processing conditions that influence the physical properties, metabolism and health attributes as well as recent application in food products.     

基于非靶标代谢组学分析不同低温贮藏方式下麻竹笋代谢物差异

目的 探究不同低温贮藏方式对麻竹笋的非靶标代谢物的影响。方法 利用超高效液相色谱-质谱法(ultra performance liquid chromatography-mass spectrometry, UPLC-MS)对不同低温(-80、-20和4℃)贮藏处理的麻竹笋样品进行非靶标代谢组学分析,筛选和初步分析差异代谢物,并进行聚类分析。结果 借助UPLC-MS的正离子模式和负离子模式,可分别实现麻竹笋中715种和369种代谢物的分析。麻竹笋非靶标代谢组学分析表明,经不同低温贮藏处理的麻竹笋组别之间均具有多种上调或下调的差异代谢物,分析后筛选出冷藏和冷冻处理的麻竹笋中的特征差异代谢物,发现低温贮藏过程中麻竹笋经过了复杂的代谢反应,营养组分发生了显著的上调或下调。麻竹笋中差异代谢物涉及到竹笋中脂代谢、氨基酸代谢等代谢通路。结论 低温贮藏下麻竹笋的非靶标代谢组学研究,为其低温保鲜及其组分代谢研究奠定了基础。