荸荠多糖的超声波辅助提取工艺

为提高荸荠多糖的得率,采用超声波辅助法提取荸荠多糖。通过单因素试验研究超声波功率、料液比、提取温度、超声处理时间、乙醇浓度对荸荠多糖得率的影响,确定荸荠多糖的最佳提取工艺。单因素试验结果表明,在本试验条件下,超声波功率为300W、料液比1：10、提取温度为50℃、超声时间25min时荸荠多糖得率最高。     

超声提取蜂胶黄酮的研究

蜂胶黄酮是蜂胶的主要活性成分,具有抗氧化、抗菌等多种功效。优化蜂胶黄酮的超声提取工艺,为蜂胶产品的开发与利用提供了理论依据。首先进行了单因素试验,研究超声功率、超声时间和乙醇浓度这三个因素分别对蜂胶黄酮提取得率的影响。在此基础上,再采用响应面法优化蜂胶黄酮的超声提取条件。研究结果表明,影响蜂胶黄酮提取得率的主次因素依次是超声时间、乙醇浓度和超声功率。当超声功率为150 W、超声时间为16 min、乙醇浓度为86%时,蜂胶黄酮提取得率实际最大可达到21.10%±0.075%(n=3)。经本实验分析可知,湖北孝感蜂胶属于蜂胶中的优等品。相比于其他超声提取蜂胶黄酮的方法,该实验的超声提取方法具有提取温度低、提取时间短的优势。     

超声-微波辅助酶法对小米SDF提取和物理性质的影响

目的为了提高小米中水溶性膳食纤维(SDF)的得率,实验采用超声-微波(U-M)辅助酶法提取小米SDF,并对提取工艺进行优化。方法以小米SDF的得率为测定指标,对微波功率、提取温度、提取时间、料液比等4个因素进行单因素试验,并利用正交试验对以上4个因素进行优化。对此条件下提取的SDF和采用传统酶法提取的SDF得率及其物理性质进行研究。结果得到了提取小米粉SDF的最优条件,微波功率为550 W,料液比(g/mL)为1:25,微波温度为55℃,微波时间为20 min,提取率为13.63%,比传统酶法提取的SDF含量提高了46.88%;通过对小米SDF物理性质的测定,发现超声-微波处理对小米SDF的持水力、膨胀力、持油力均有显著提高,分别提高了24.79%,25.16%,15.74%。结论通过超声-微波辅助酶法可以提高小米SDF的得率,对其物理性质影响显著。     

基于响应面法优化无子刺梨总皂苷提取条件

目的 优化超声辅助提取无子刺梨总皂苷的条件,以提高总皂苷的提取效率.方法 通过单因素试验评估乙醇体积分数、超声时间、料液比和提取次数对总皂苷得率的影响,结合响应面法的中心组合实验设计,确定其最佳提取条件.结果 在超声时间为40 min、乙醇体积分数为60％、料液比(g/mL)为1:30、提取4次的条件下,总皂苷的得率为9.15％,与模型预测值9.18％较为接近,表明了响应面法优化无子刺梨总皂苷的超声辅助提取方法的可行性.结论 此研究为无子刺梨资源在食品贮藏、医药等方面的进一步开发利用提供参考依据.     

基于响应曲面法的桑叶萃余物多糖提取工艺优化

以提取生物碱和黄酮的桑叶萃余物为原料,采用响应曲面分析法(RSM)优化桑叶萃余物多糖的超声提取工艺。在单因素实验的基础上,选取对实验结果影响较大的因素:提取时间、提取温度、水料比,根据中心组合(BoxBenhnken)实验设计原理对桑叶多糖的超声提取工艺进行优化,苯酚-硫酸比色法测定桑叶多糖的含量。在分析各个因素的显著性和交互作用的基础上,得到最佳提取工艺条件为:提取温度79.29℃、超声波时间35.90min、水料比8.78mL/g。采用该工艺条件,桑叶多糖的提取得率达到2.97%。与模型预测值相符。     

罗汉松种子总黄酮提取工艺优化及抗氧化活性

目的 采用响应面法优化罗汉松种子总黄酮超声提取工艺，并考查总黄酮的抗氧化活性。方法 基于单因素试验，以料液比、超声时间、超声温度为自变量，以总黄酮得率和DPPH自由基的清除率为因变量，采用三因素三水平的响应面分析法，确定最佳提取工艺条件。结果 得到最佳工艺参数：在超声频率为40 kHz、超声功率为200 W时，料液比（g/mL）为1∶50、超声温度为70℃、超声时间为2.7 h，其理论预测值总黄酮得率为27.54mg/g(n=3，相对标准偏差为1.63%)。当添加稀释10倍的总黄酮提取液0.50mL时，对DPPH自由基的清除率达到87.2%、对Ce（Ⅳ）还原率达到84.2%；当添加稀释10倍的总黄酮提取液0.90mL时，对OH自由基的清除率为88.1%。结论 采用响应面法优化得到的超声波辅助提取工艺稳定、可靠，可用于罗汉松种子总黄酮的提取。罗汉松种子总黄酮可作为优良的天然抗氧化剂资源。     

超声波-乙醇法提取树莓酮及抗脂质过氧化研究

目的为了探究天然树莓酮提取的最佳工艺条件,以及树莓酮的抗脂质过氧化作用。方法以红树莓为原料,选用超声辅助乙醇提取法提取树莓酮,采用气相色谱法测定树莓酮含量。基于单因素实验结果,以料液比、乙醇浓度、超声时间和温度为影响因子,树莓酮得率为响应值,设计响应曲面优化实验,并研究树莓酮的抗脂质过氧化作用。结果得到树莓酮最佳提取条件,料液比(g/mL)为1∶15、乙醇体积分数为85%、超声时间为50 min,超声温度为40℃。在此条件下验证了实验,得出树莓酮含量为2.803μg/g,抗蛋黄卵磷脂脂质过氧化能力趋势为Vc溶液>树莓酮粗提液>树莓酮标准溶液。结论超声波辅助乙醇提取法可有效应用于红树莓中树莓酮的提取,且树莓酮粗提液对由Fe^2+诱导的脂质过氧化有一定的抑制作用。     

双频超声强化从海金沙中提取黄酮的实验研究

采用双频超声强化从海金沙中提取黄酮的研究结果显示:在27℃,海金沙质量与乙醇体积比为0.05g/ml,搅拌器转速、超声功率及频率不变的条件下,质量浓度达到平衡时的60%,搅拌提取需700min以上,槽式超声需105min,探头式超声需45min,而双频超声所需时间不到20min;若提取时间均为60min,则双频超声的提取率为搅拌的11倍,为槽式超声的2倍,为探头式超声的1.8倍。通过选择乙醇浓度、溶剂用量、超声作用时间、浸泡时间因素进行正交实验,得出双频超声提取最佳工艺条件:浓度70%用量为40ml的乙醇,超声作用时间30min,浸泡时间为4h。机理探讨表明,当两束超声波同时传播时,超声作用的均匀性增强,声强增大,使得海金沙颗粒的边界层变薄,外表面剥落,甚至使其颗粒发生碎裂,传质速率大大提高,试验结果表现为双频超声对提取过程具有协同增强作用。     

枸杞色素的闪式提取和超声-微波协同提取工艺

目的 以枸杞为原料,比较不同提取工艺对枸杞色素吸光值的影响,以确定枸杞色素的最佳提取工艺.方法 通过单因素试验和响应面法对枸杞色素的闪式提取和超声-微波协同提取工艺进行研究.结果 闪式提取枸杞色素的最佳工艺条件为料液比(g/mL)1︰13,提取电压113 V,提取时间112 s,该条件下枸杞色素吸光度为0.457;超声-微波协同提取枸杞色素的最佳工艺条件为料液比(g/mL)1︰16,微波功率613 W,提取温度55℃,提取时间32 min,该条件下枸杞色素吸光度为0.502.结论 对2种提取方法在最佳工艺条件下进行比较,超声-微波协同提取法提取枸杞色素的效果优于闪式提取法.     

超声波协同法提取荷叶中总黄酮的研究

采用超声波协同提取法对荷叶总黄酮进行提取,通过单因素试验确定最佳的荷叶总黄酮提取工艺：提取时间20min,料液比1：30,乙醇浓度60％,温度50℃,验证试验证明实际提取率为4．85％。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.