环氧基功能化块体SiO_2大孔材料对漆酶的固定化

采用后嫁接法在溶剂热条件下对新型块体SiO2大孔材料进行环氧基化改性,以环氧基功能化SiO2大孔材料作为载体,通过共价结合法固定化诺维信(Novozymes)工业级漆酶,对固定化条件进行了优化,研究了固定化酶与游离酶的酶学性质。结果表明,在固定化时间为4 h、pH值为4.5、初始酶液浓度为25 mg/mL时,固定化效果最好,固定化漆酶活力达到101.7 U/g;固定化漆酶的最适pH值为4.0,最适温度为50℃,其pH值稳定性和热稳定性都显著优于游离漆酶。固定化漆酶具有可重复操作的性质,与底物反应反复操作10批次后剩余活性为43.4%。     

AB-8大孔吸附树脂固定化过氧化氢酶的研究

利用AB-8大孔吸附树脂作为载体、戊二醛为交联剂时过氧化氢酶进行了固定化,研究了其最优固定化条件及稳定性.结果表明,最佳固定化条件为:吸附温度35℃,pH值7.0,吸附时间6h,加酶量每克载体970U,戊二醛体积分数0.2%,交联时间2h.固定化过氧化氢酶的最高酶活收率达到45.2%.固定化酶的热稳定性、酸碱稳定性都较游离酶有了一定的提高,重复使用10次,酶活仍能稳定保持在初始酶活的60%以上,具有良好的操作稳定性.     

固态酶型时间温度指示器性能研究

目的以糖化酶、淀粉为主要原料,研制一种激活方便的固态酶型时间-温度指示器。方法对糖化酶进行微胶囊化处理,以糖化酶反应体系为基础,研究不同因素对指示器色差值的影响,确定在4℃条件下,时间在5~6 d的指示器配比。结果确定了固态酶型TTI的反应配方,通过测定其在不同温度下的反应速率,得到了7组TTI体系的活化能,其活化能值分别为106.68,98.47,87.66,89.73,106.74,97.51和87.99 k J/mol。结论得到可用于4℃条件下的时间温度指示器的7组配方,根据其活化能的不同,可用于指示不同产品的货架期。     

碳酸酐酶在硅藻土上的固定化及其性质研究

以硅藻土为载体,通过共价结合法固定化碳酸酐酶.对制备固定化晦过程中的pH值、加酶量、反应温度、反应时间几个重要的影响因素进行了研究和优化,并对固定化酶和游离酶的酶学性质进行了比较.结果表明,固定化酶的最适反应温度为30℃,比游离酶高了5℃;最适反应pH值为6.0,比游离酶低了2个pH值单位.该固定化酶的热稳定性、酸碱稳定性和操作稳定性均高于游离酶.     

单宁微球固载α-淀粉酶及其催化性能

以单宁微球为载体,采用戊二醛交联法固定α-淀粉酶。探讨了最佳固定化条件,并考察了温度、pH值和淀粉初始浓度等对固定α-淀粉酶催化淀粉水解的影响。结果表明,单宁微球对α-淀粉酶的吸附率达到了96.99%。最佳固定条件为:戊二醛质量分数0.10%,pH5.5,温度25℃,时间2h。固定α-淀粉酶的重复5次后仍具有较好的催化效果。     

温度对碱性脂肪酶型 TTI 可靠性的影响

酶型时间-温度指示器是一种新型的包装食品质量指示装置,在生产后到使用前的贮藏过程中酶活的变化直接关系到在应用中的可靠性。研究了25,37,50℃条件下,基于扩散显色的酶型时间-温度指示器(TTI)中酶活的变化规律,进行了动力学建模,并通过其动力学方程对该TTI在0℃和3℃下的品质变化状况进行了预测和验证。结果表明,该酶基体系在0℃贮藏180 d仍可以保持88.37%的相对酶活,与理论预测酶活的相对误差为3.37%。根据Orellana的研究标准,其相对酶活大于85%,可以有效保持其扩散显色特性。     

氧化硅介孔泡沫材料固定木瓜蛋白酶的研究

以氧化硅介孔泡沫材料(Siliceous Mesocellular Foam, MCF)为载体对木瓜蛋白酶进行了固定, 并对固定化酶的性能和影响因素以及酶的稳定性作了系统的研究. 结果表明, 木瓜蛋白酶在MCF上能获得较大的负载量（334mg/g MCF）. 固定化木瓜蛋白酶的最适反应温度较游离酶提高了10℃, 最适pH向碱性方向偏移0.5个单位. 固定化木瓜蛋白酶的米氏常数（Km）为6.99×10^-3mol/L, 在八批次操作后酶活保留65.1%. 在4℃条件下放置60d后, 固定化酶的剩余活性仍保持75%以上, 而游离酶的活性只有初始活性的53.6%. 与游离酶相比, 固定化木瓜蛋白酶的pH稳定性、热稳定性、操作稳定性和储藏稳定性都有明显改善, 有利于酶的重复使用和储藏. 介孔泡沫材料是一种良好的木瓜蛋白酶固定载体.     

双水相体系萃取虎舌红皂苷及稳定性研究

目的 选用聚乙二醇（PEG）-硫酸铵（(NH4)2SO4）双水相体系萃取虎舌红皂苷,并研究皂苷的稳定性。方法 以萃取率为指标,考察水浴时间、水浴温度、PEG平均分子量、PEG质量分数、(NH4)2SO4质量分数、体系pH值对萃取效果的影响,采用响应曲面法对萃取条件进行优化,并对虎舌红皂苷进行稳定性研究。结果 得到了最佳萃取条件,水浴时间为40 min,水浴温度为70 ℃,PEG600质量分数为25.0%,(NH4)2SO4质量分数为21.0%,pH值为6.20,此时虎舌红皂苷的萃取率为4.73%。研究表明,虎舌红皂苷适于保存在20 ℃以下、pH为6的低温微酸性环境中。结论 此体系的建立能有效萃取虎舌红皂苷,为其后续研究提供参考依据。     

碳酸酐酶在地质聚合物微球表面的固定及活性表征

碳酸酐酶(Carbonic anhydrase, CA)是一种广泛存在于各种真核生物以及原核微生物中的含锌金属酶，可以高速催化CO₂的可逆水合反应，但其成本昂贵，且易失活、难回收，因此实际应用受到了限制。酶的固定化技术不仅可以使酶像固体催化剂一样可回收再利用，还能提高酶的稳定性，保持其高催化性能。固定化酶具有一定的机械强度和形状，可置于反应床或连续反应器中生产，且反应过程可控。本研究以绿色环保、来源广泛的矿渣为原料，以NaOH为碱激发剂，通过悬浮分散固化法制备了地质聚合物微球并将其作为载体；以戊二醛为交联剂，使用吸附-交联法成功地将碳酸酐酶(Carbonic anhydrase, CA)固定在地质聚合物微球上。通过酶活回收率和相对酶活来评价碳酸酐酶的固定化效率，同时利用不同的表征手段对载体与固定化酶的微观形貌、结构变化等进行了对比分析。实验结果表明，碳酸酐酶在地质聚合物微球上的最佳固定化条件为pH值8.0、反应温度30℃、固定化时间2 h、载体用量100 mg、交联剂浓度0.2%(质量分数)、交联反应时间1 h。在此条件下的固定化碳酸酐酶的酶活回收率最高可达55....     

基于嗜酸乳杆菌的时间温度指示器的制备及其性能表征

目的 为了监测食品贮藏和运输期间的品质,制备微生物时间-温度指示器(TTI)。方法 选择嗜酸乳杆菌作为时间-温度指示器的微生物,对配制成的9种混合pH指示剂溶液进行筛选,用合适的混合pH指示剂溶液制备TTI,加入不同浓度的嗜酸乳杆菌,在不同等温条件下(5、15、25℃)贮藏检测其指标,以合适的指标参数为响应值探究其动力学与温度依赖性。结果 9种混合pH指示剂溶液中有5种颜色变化较明显,用其中一种制备TTI,以色差值(?E)为响应参数得出其活化能(E_a)为84.9 kJ/mol。结论 5种颜色变化较明显的混合pH指示剂溶液可以作为TTI的指示剂,制备的微生物型TTI有潜力应用于活化能59.9 kJ/mol≤E_a≤109.9 kJ/mol的食品品质指标的货架期预测中。     

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.