壳聚糖/淀粉/ZnO复合膜的制备与性能

目的以壳聚糖和玉米淀粉为主要成膜基质,以纳米ZnO为添加剂,研究复合膜的相关结构和性能。方法采用溶液共混法将壳聚糖溶液、淀粉糊化液及纳米ZnO质均混合,然后流延成膜,分析壳聚糖/淀粉的质量比和纳米ZnO的含量对复合膜力学性能、水蒸气透过率(WVP)的影响,并通过红外光谱、扫描电镜、X射线衍射和热重分析对复合膜的相关结构进行表征。结果当壳聚糖/淀粉质量比为1∶1,纳米ZnO质量分数为9%时,所得膜在各自体系中的性能较佳。结论壳聚糖和淀粉二者之间具有较好的相容性,纳米ZnO的加入能增强复合膜的力学性能,降低其水蒸气透过率,并提高复合膜的热稳定性。     

学术前沿

正壳聚糖/淀粉/ZnO复合膜的制备与性能作者:郑科旺,付梅芳,黄超凡,颜永斌,李伟,覃彩芹来源:包装工程,2017(7)摘要:目的是以壳聚糖和玉米淀粉为主要成膜基质,以纳米ZnO为添加剂,研究复合膜的相关结构和性能。方法采用溶液共混法将壳聚糖溶液、淀粉糊化液和纳米Zn O质均混合,然后流延成膜,分析壳聚糖/淀粉的质量比和纳米ZnO的含量对复合膜力学性能、水蒸气透过率(WVP)的影响,而且通过红外光谱、扫描电镜、X射     

甲壳素纳米纤维增强明胶/壳聚糖复合膜的制备及性能研究

通过流延成膜法制备了不同甲壳素纳米纤维(CF)质量分数的CF/明胶(GA)/壳聚糖(CS)复合膜。利用透射电子显微镜(TEM)、扫描电子显微镜(FE-SEM)、紫外-可见光谱(UV-Vis)等对材料的结构与性质进行了研究。结果表明:低加入量CF在复合膜中分散较好,高加入量CF在复合膜中会形成团聚,CF与GA/CS之间有相对较好的相容性;随着CF含量增加,复合膜拉伸强度呈现先增加而后减小的趋势,而断裂伸长率则随着CF含量增加而持续降低;同时复合膜的水蒸气吸附率和水溶失率都随着CF含量的上升而降低。CF/GA/CS纳米复合膜表现出良好的透明性,较少CF的加入对材料透明度影响不大。     

可食性淀粉/壳聚糖复合膜的制备与性能研究

目的 利用壳聚糖对淀粉改性制备可食性复合膜,研究复合膜的结构与性能。方法 通过溶液共混法将壳聚糖的乙酸溶液与淀粉糊化液均匀混合,然后流延成膜,分析壳聚糖、甘油、Na Cl含量对复合膜的力学性能、水蒸气透过率的影响,通过X-射线衍射、扫描电镜和热重分析对复合膜的结构和性能进行表征分析。结果 复合膜中淀粉与壳聚糖两组分具有良好的相容性;甘油和Na Cl的添加有利于促进淀粉的塑化,改善复合膜的柔性,同时影响其力学强度和水蒸气透过率。结论 当淀粉与壳聚糖质量比为5∶3、甘油质量分数为25%、Na Cl质量分数为5%时,所制备的膜具有优异的综合性能。     

南极磷虾甲壳素纳米晶须的制备与应用

利用南极磷虾壳制备甲壳素，然后采用TEMPO氧化法将其制备成甲壳素纳米晶须，将不同添加量的甲壳素纳米晶须加入壳聚糖/鱼胶基体中，制备壳聚糖/鱼胶/甲壳素纳米晶须复合膜材料。通过扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)和傅里叶红外光谱(FTIR)对甲壳素纳米晶须进行分析；通过SEM、光透射率、 XRD、热重分析(TG)对复合膜材料进行检测；通过小鼠皮下埋植实验对复合膜材料的降解性进行测试。研究结果表明，利用南极磷虾壳所制备的甲壳素纳米晶须呈针状或纤维状，平均直径为17 nm;甲壳素纳米晶须能够均匀分散在复合膜材料中，当甲壳素纳米晶须的添加量为7%时，复合膜的拉伸强度达到最大为18.37 MPa,相比于壳聚糖/鱼胶膜提高了160%,这说明纳米晶须添加到复合膜中能显著提高其机械强度。小鼠皮下降解实验表明，添加纳米晶须的复合膜降解速度变慢，第九周时，添加7%纳米晶须的膜材料降解率为66.2%。     

茶多酚对壳聚糖/聚乙烯醇复合膜性能的影响

目的以茶多酚为改性剂对壳聚糖/聚乙烯醇复合膜进行共混改性,制备一种综合性能良好的绿色包装材料。方法采用溶液共混法制备不同茶多酚质量分数的壳聚糖/聚乙烯醇复合膜,并对其进行红外光谱分析,以及力学性能、水溶性、气体阻隔性、抗氧化性能的测试。结果茶多酚与壳聚糖/聚乙烯醇基质间发生了分子间相互作用,当茶多酚的质量分数为2%时复合膜的综合性能最好,拉伸强度提高了4.99%,且可保持较高的断裂伸长率,水溶性、水蒸气透过率和氧气透过率分别降低了82.43%,51.40%和72.77%,抗氧化能力增强了58.54%。结论添加适量的茶多酚能够提高壳聚糖/聚乙烯醇复合膜的力学性能和耐水性,并改善其气体阻隔性和抗氧化性能。     

载银纳米纤维素-壳聚糖复合膜的表征及性能研究

在二醛基纳米纤维素悬液中加入银氨溶液原位合成载银纳米纤维素(Ag/DNCC),以壳聚糖(CS)为成膜基底,甘油为增塑剂,加入Ag/DNCC共混流延制备载银纳米纤维素-壳聚糖(Ag/DNCC-CS)复合膜。FT-IR和XRD测试结果表明Ag/DNCC的加入没有改变CS的分子结构和结晶状态,热性能测试结果表明Ag/DNCC对提高CS的热稳定性能不显著。添加Ag/DNCC后,SEM测试结果表明Ag/DNCC-CS复合膜微观形貌致密,拉伸强度比纯CS膜提高。Ag/DNCC含量为10%(wt,质量分数)制得的Ag/DNCC-CS复合膜的拉伸强度达到72.36MPa,对大肠杆菌和金黄色葡萄球菌均有较好的抑菌效果。     

基于茶多酚的壳聚糖基抗氧化复合膜的制备与性能研究

以壳聚糖为基体、茶多酚(TP)为活性抗氧化物,通过流延法制备了壳聚糖/茶多酚复合膜,对复合膜的力学性能、透光率、颜色、溶胀度、溶解性、氧气透过率、抗氧化等性能进行了研究。结果表明:随着茶多酚的增加,复合膜颜色加深,透光率降低;拉伸强度增加,断裂伸长率降低;含水量、溶胀度与溶解度降低,耐水性增强;自由基清除率升高,抗氧化性增强;茶多酚含量为20%(wt,质量分数)的复合膜阻氧性能较好。     

明胶-壳聚糖/纳米SiO_2原位载药复合膜的制备及性能研究

利用明胶、壳聚糖和纳米SiO_2,制备了明胶-壳聚糖/纳米SiO_2复合膜,对复合膜的溶胀性、机械强度等进行测试。然后将明胶-壳聚糖/纳米SiO_2复合膜用于阿司匹林的原位负载,研究纳米SiO_2用量和模型药物阿司匹林用量对原位载药复合膜缓释性能的影响。结果表明,纳米SiO_2的引入能够降低复合膜在水中的溶胀性,提高复合膜的机械强度;随着纳米SiO_2用量的增加,复合膜原位负载阿司匹林的缓释效果增加;阿司匹林用量为0.5%时,明胶-壳聚糖/纳米SiO_2原位载药复合膜具有较好的缓释效果。     

分心木碳点/聚乙烯醇复合膜的制备及其在草莓保鲜的应用

目的 制备不同浓度碳点的未掺杂分心木碳点（1-CDs）/聚乙烯醇复合膜和氮掺杂分心木碳点（2-CDs）/聚乙烯醇复合膜,以延长草莓的货架期。方法 采用流延法制备复合膜,探讨不同浓度CDs对复合膜的光致发光行为、疏水性、力学性能、紫外吸收性能和阻隔性能的影响,并比较不同薄膜对草莓的保鲜效果。结果 碳点和聚乙烯醇分子内或分子间发生了较强的相互作用,碳点的加入增强了复合膜的疏水性和紫外吸收性能,2-CDs/PVA-6复合膜在60s时的接触角为65.3°,断裂伸长率和拉伸强度分别为(220.6±6.3)%、(107.55±4.9)MPa,2-CDs/PVA-6复合膜在波长300 nm时的紫外可见光透过率接近0,该复合膜对草莓的保鲜效果最好。结论 作为包装材料,2-CDs/PVA-6复合膜表现出潜在的应用价值,能够延长草莓的货架期。     

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 ...     

Effect of Oxide Assisted Metal Nanoparticles on Microstructure and Morphology of Gallium oxide Nanowires

Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD.     

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