纳米ZnO的抗菌性能研究

纳米ZnO是一种常见的光学材料,将其与其他材料复配可以制得抗菌性能良好的包装材料。根据GB/T 21510—2008《纳米无机材料抗菌性能检测方法》,以大肠杆菌和金黄色葡萄球菌为测试菌种,以SiO2为对照试验,测试了纳米ZnO对大肠杆菌和金黄色葡萄球菌的抗菌性能;同时,采用抑菌圈法对其抗菌性能进行了定性研究。结果表明：纳米ZnO对大肠杆菌和金黄色葡萄球菌具有良好的抑菌性能,且初步测定了纳米ZnO对这两种菌的最小抑菌浓度,分别为0.312 5%和0.625%;纳米ZnO对大肠杆菌和金黄色葡萄球菌高度敏感,纳米ZnO对二者的抑菌圈直径都大于15 mm。     

TiO_2/ZnO粒子的制备及其抗菌性能

采用溶胶凝胶法制备了TiO2/ZnO复合粒子,通过XRD、SEM对所制备粉体颗粒的物相组成以及表面形貌进行表征,通过最小抑菌浓度法(MIC)研究了不同掺杂量的TiO2/ZnO复合粒子的抗菌性能。结果表明,掺杂TiO2的ZnO粒子显示优良的抗菌活性,对金黄色葡萄球菌(Staphylococcusaureus)的MIC≤62.5μg·mL-1。当TiO2的掺入量为20%,所得到的ZnO粒子的抗菌性能最佳,对绿脓杆菌、大肠杆菌、枯草芽孢杆菌、金黄色葡萄球菌四种菌的抑菌性能均有显著提高,并对其机理做了初步探讨。     

卤胺季铵盐双活性抗菌剂的制备及其在纤维基包装材料中的应用

目的 在温和实验条件下制备卤胺季铵盐双活性抗菌剂,考察其抗菌活性并研究其在纤维基包装材料中的应用。方法 利用紫外-可见分光光度计标定标准曲线,考察双活性抗菌剂及负载该抗菌剂的纤维基包装材料的抗菌活性和再生复用性能。结果 双活性抗菌剂在质量浓度为0.25 g/mL时,15 min内对大肠杆菌和金黄色葡萄球菌的杀菌效果均达到100%;负载双活性抗菌剂的纤维基包装材料在15 min内对大肠杆菌和金黄色葡萄球菌的杀菌效果均达到100%;经3次抗菌性能再生后,双活性抗菌剂和纤维基抗菌包装材料的一次杀菌效果仍可达到100%。结论 双活性抗菌剂对革兰氏阴性菌(大肠杆菌)与革兰氏阳性菌(金黄色葡萄球菌)均有良好的灭菌作用,负载双活性抗菌剂的纤维基材料的灭菌效果良好,且抗菌性能可多次再生。     

铜原位改性HMS材料的表征及抗菌性能

采用溶胶凝胶法,原位合成了铜改性的六方介孔硅 (Cu-HMS)无机抗菌材料. XRD、TG-DTA、ESR、UV-Vis、FT-IR、ESEM、EDS及N₂吸附脱附等对材料结构与性能进行了表征;以大肠杆菌、金黄色葡萄球菌、枯草杆菌及芽孢杆菌作供试菌种,考察了材料的抗菌性能. 结果表明,材料粒子呈规则的叶片状,比表面积为553m²/g,平均孔径约3.6nm,铜以离子形式存在于材料的骨架结构中,材料具有良好的介孔结构和热稳定性,有优良的紫外-可见光吸收性能;在抗菌实验中,材料的抗菌效能较好,抗菌性能稳定持久. 材料用量20mg/L,12h即表现出明显的抑菌作用;用量为200mg/L时,24h后可彻底杀灭大肠杆菌、金黄色葡萄球菌及枯草杆菌.     

不同Sol-Gel前躯体体系制备纳米ZnO粉体的研究

为研究不同溶胶前躯体体系对制备纳米ZnO粉体粒径大小的影响,采用溶胶-凝胶法分别研究了硬脂酸体系、草酸体系、高分子网络体系制备纳米ZnO粉体,并利用TG-DTA、XRD、TEM对其结构、形貌和粒径进行了表征.在3种体系中,高分子网络体系所得粉体粒径最小,粒径在30～40nm,粒径大小均匀,团聚较少.硬脂酸体系得到ZnO粉末粒径较小,范围分布在30～50nm,分散性较好.草酸体系制得ZnO粉末粒径相对较大,在40～60nm,有轻微团聚.     

负载卟啉镓化合物的水凝胶材料抗菌性能研究

通过高分子聚合法制备了两性离子水凝胶材料聚羧基甜菜碱(pCB)和非离子水凝胶材料聚甲基丙烯酸羟乙酯(pHEMA),运用菌落计数法测定了阳离子改性卟啉镓(Ga-CMP)对金黄色葡萄球菌(S.aureus)和大肠杆菌(E.coli)的最低抑菌浓度；考察了负载卟啉镓化合物的水凝胶缓释释放速度和抗菌性能。结果表明，阳离子改性卟啉镓对金黄色葡萄球菌和大肠杆菌最低抑菌浓度分别为4μM和10μM。负载有Ga-CMP的水凝胶材料在30天内的测试区间表现出了持续释放。500μg/mL pHEMA-Ga-CMP在12 h对金黄色葡萄球菌完全抑制，在8 h对大肠杆菌完全抑制；500μg/mL pCB-Ga-CMP在24 h对金黄色葡萄球菌完全抑制，在24 h对大肠杆菌完全抑制。     

纳米掺锶羟基磷灰石的制备及其抗菌性能研究

以硝酸钙、氯化锶、磷酸氢二氨等为原料,采用溶胶-凝胶-超临界流体干燥法,制备了纳米掺锶羟基磷灰石(SrHAP).通过元素含量分析、TEM、XRD、FT-IR等手段对其结构进行了表征,分析了锶的掺入对羟基磷灰石(HAP)的结构、晶形及结晶度的影响;研究了HAP掺入锶后对大肠杆菌、金黄色葡萄球菌、乳酸杆菌的抗菌性能.结果表明:采用溶胶-凝胶-超临界CO2干燥法,可制备结晶性较好的纳米HAP和Sr/[Sr Ca]原子比为0.5的纳米SrHAP;在给定的条件下,锶可以按化学计量比掺入到HAP的结构中;HAP掺入锶后,其主要官能团红外光谱吸收峰的振动频率降低,晶形从HAP的短棒状改变为SrHAP的针状,结晶度降低,对大肠杆菌、金黄色葡萄球菌、乳酸杆菌的抗菌性能提高.     

形貌和光照条件对ZnO抗菌性能的影响

检测了四针状氧化锌晶须、纳米氧化锌和普通工业级氧化锌的抗菌性能,比较了形貌和光照条件对ZnO抗菌性能的影响,并研究了ZnO对不同菌种的抗菌性能差异.结果表明,Zno形貌对其抗菌性能有较大影响,有光条件下ZnO抗菌性能大于无光条件下,3种ZnO对大肠杆菌的抗菌性能均比对金黄色葡萄球菌好.     

壳聚糖/有机锂皂石纳米复合材料的制备及抗菌性能研究

采用离子交换法将季铵盐及壳聚糖插层到锂皂石层间, 制备锂皂石基二次插层复合物。所制备的两种二次插层复合物的层间距相比于纯的锂皂石分别增加了0.276 nm和0.262 nm。用大肠杆菌(E. coli)和金黄色葡萄球菌(S. cereus)为模拟体系对二次插层复合物的抗菌性进行了检验, 利用抑菌环和平板计数法测定两种二次插层复合物的抗菌能力。抗菌结果显示, 细菌与两种复合物接触24 h后, 锂皂石/十四烷基三甲基溴化铵/壳聚糖对大肠杆菌的抗菌率可达100%, 对S.cereus的抗菌率可达85%以上, 锂皂石/十六烷基三甲基溴化铵/壳聚糖对大肠杆菌和金黄色葡萄球菌的抗菌率均可达99%以上。采用扫描电镜法及β-半乳糖苷酶活性考察了两种复合物对大肠杆菌和金黄色葡萄球菌抑菌过程及机理, 结果表明: 复合物首先通过表面带的正电荷将表面带负电的细菌吸附到材料表面, 随后借助有机物阳离子的疏水作用, 穿透细菌细胞膜, 从而达到杀菌效果。     

二氧化硅/壳聚糖复合微球的制备及性能

通过溶胶-凝胶法制备出3种不同粒径的SiO₂微球，利用扫描电镜分析了微球的粒径分布情况，SiO₂微球粒径分别在140nm、208nm、336nm左右，在一定范围内，硅球的粒径随正硅酸四乙酯(TEOS)/氨水的添加量增加而增大。选取粒径在336nm左右的SiO₂微球，使用硅烷偶联剂3-(2,3-环氧丙氧基)丙基三甲氧基硅烷(GPTMS)将壳聚糖(CS)接枝在SiO₂微球上，得到SiO₂@CS复合微球。通过红外光谱分析、X射线衍射等对微球进行了表征。接枝CS后对SiO₂微球的结晶特性没有影响，微球仍为无定形晶体。元素分析结果表明CS的接枝量为1.03%。使用振荡法进行抗菌测试，SiO₂@CS复合微球对金黄色葡萄球菌(S.aureus)和大肠杆菌(E.coil)的抑菌率分别为85.52%和47.14%,表明复合微球有一定的抗菌效果。     

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.