牛至精油微胶囊的制备及其抑菌效果研究

以海藻酸钠为壁材制备牛至精油微胶囊,通过正交试验优化了微胶囊的最佳制备工艺条件,并对其进行了结构表征和抑菌效果研究。结果表明,制备牛至微胶囊的最佳工艺条件为:海藻酸钠质量分数2.5%、氯化钙质量分数1.5%、壁芯比为1∶1、乳化剂为0.2%的吐温-80和0.1%的单甘酯,在此条件下,微胶囊中牛至精油的包埋率为60.48%,其内部为多孔结构,且抑菌效果良好,当其用量达到0.02g时,对灰霉的抑菌圈直径达到90mm。     

牛至精油β环糊精微胶囊的制备及其抑菌效果研究

目的制备牛至精油β环糊精(β-CD)微胶囊,并研究其抑菌效果。方法首先,选用β-CD包埋牛至精油,通过扫描电镜观察该包埋物的外部形貌特征。其次,通过薄层色谱、红外光谱等2种方法考察是否已成功制备牛至精油β环糊精的微胶囊。然后,通过紫外分光光度计测定该包埋物的吸光度,按照一定的方法计算其包埋率。最后,选用大肠杆菌、米曲霉菌作为供试菌株,研究该包埋物的抑菌效果。结果牛至精油β环糊精微胶囊得到成功制备,其包埋率为73%,并且该包埋物具有较好的抑菌效果。结论实验达到了预期目的,即在保留牛至精油抑菌性能的同时,也使得液体的牛至精油固体粉末化。     

肉桂精油微胶囊抗菌水性油墨的研制

目的为了满足食品包装对油墨安全性的要求,研制一种具有缓释抗菌特性的水性油墨。方法以β-环糊精为包埋材料,采用超声波法制备肉桂精油微胶囊,设计L_9(3~4)正交实验方案,研究芯材(肉桂精油)与壁材(β-环糊精)的质量比,壁材与水的质量比,反应转速,反应时间等对包埋率的影响。以制备的肉桂精油微胶囊为抗菌剂,辅以水性丙烯酸酯树脂、颜料、填料、水及各类助剂制备抗菌水性油墨,选用大肠杆菌和青霉菌检测油墨的抗菌性。结果确定了超声波法制备肉桂精油微胶囊的最佳工艺条件,芯壁质量比为1∶5,壁材与水的质量比为1∶8,反应转速为2000 r/min,时间为6 min,此条件下可制备包埋率为33.88%的肉桂精油微胶囊。抗菌性检测结果表明,肉桂精油微胶囊抗菌水性油墨对大肠杆菌和青霉菌均有显著的抑制作用,当肉桂精油微胶囊质量分数为7%时,对大肠杆菌和青霉菌的抑菌圈直径分别为24 mm和17 mm。结论通过添加肉桂精油微胶囊,可制备具有显著抗菌性的水性油墨,提升了水性油墨在食品包装方面的应用价值。     

枝叶精油微胶囊工艺优化及缓释性能研究

目的研究桉叶精油微胶囊的最佳包埋工艺。方法以β-环糊精为壁材制备桉叶精油微胶囊,通过单因素和正交试验研究微胶囊包埋工艺,确定最优包埋工艺条件。结果最佳包埋工艺中包埋温度为40℃,包埋时间为1.5 h,β-环糊精质量浓度为8 g/mL。在该条件下制得的微胶囊包埋率为70.33%,微胶囊收率为86.27%。缓释试验结果表明,微胶囊化可以明显降低桉叶精油的挥发速率,Avrami's方程也可以对桉叶精油微胶囊释放过程进行较好拟合。结论试验达到了预期目的,微胶囊化提高了精油利用率,延长了桉叶精油的使用寿命。     

可食微胶囊涂层对鲜切紫玉淮山抗褐变效果研究

目的研究绿色、环保、安全的鲜切果蔬保鲜方法,以延缓鲜切紫玉淮山的褐变进程。方法以β-环糊精为壁材,牛至精油为芯材,蔗糖脂肪酸酯为乳化剂,利用分子包埋法制备β-环糊精-牛至精油微胶囊;以褐变度为评价指标,通过实验确定抗褐变效果最佳的柠檬酸和海藻酸钠浓度;通过将微胶囊、柠檬酸和海藻酸钠共混制备可食微胶囊涂层,探究可食β-环糊精-牛至精油微胶囊涂层对鲜切紫玉淮山的抗褐变效果。结果β-环糊精-牛至精油微胶囊的表面呈褶皱和堆叠状,且微胶囊形态饱满、大小均匀,粒径大约在40～50μm之间;通过实验确定抗褐变效果最佳的柠檬酸和海藻酸钠的质量分数分别为0.8%和1.5%;通过扫描电子显微镜观察可知,可食涂层已成功附着在鲜切紫玉淮山表面,且可食涂层较为平整。结论在24 h的贮藏期内,β-环糊精-牛至精油微胶囊涂层能明显减缓鲜切紫玉淮山的褐变进程。     

丁香精油β-环糊精微胶囊制备工艺条件的优化

介绍了丁香精油的性能和其作为食品防腐剂的局限性。以β-环糊精(β-CD)为壁材制备了丁香精油微胶囊,通过正交试验对微胶囊制备工艺条件进行了优化。结果表明:微胶囊制备比较适宜的条件为β-CD与水比质量比为1∶6,芯材与壁材体积质量比为1∶6,溶媒乙醇的体积分数为60%,丁香精油与溶媒体积比为1∶20,微胶囊化的温度为60℃,时间为2.5 h。由此可得到包合得率为76.86%,包埋率为22.32%,粒径50~80nm的微胶囊颗粒。     

肉桂精油微囊化及其在果蔬保鲜中的应用

目的以壳聚糖、海藻酸钠为壁材,以肉桂精油为芯材,采用复凝聚法制备壳聚糖微胶囊,并将其应用于水果保鲜中。方法通过光学显微镜、扫描电子显微镜、傅里叶转化红外光谱等,确定微胶囊的最佳工艺参数、芯壁比及添加质量分数,并以芒果为实验对象,研究添加不同微胶囊质量分数的壳聚糖溶液对芒果保鲜效果的影响。结果当壳聚糖/海藻酸钠质量比为1∶2,氯化钙质量分数为1%,p H值为5,戊二醛质量分数为60%,交联时间为60 min,芯壁比为4∶1时,制备形成的壳聚糖微胶囊成球效果较好;微胶囊在壳聚糖溶液中的添加质量分数为4%时,以其涂膜的芒果保鲜效果最佳。结论肉桂精油经囊化后有效减少了气味、延缓了挥发,在果蔬保鲜中有较重要的现实研究意义。     

植物精油复配抑菌性能分析

目的 以对纸质品造成主要危害的黑曲霉、草本枝孢霉及球毛壳霉为实验菌株,研究牛至、柠檬草和丁香精油的复配抑菌性能。方法 采用滤纸片扩散法研究3种植物精油的抑菌效果,并检测其抑菌持久性;通过三因子二次正交旋转设计探索3种植物精油两两复配的复合抑菌性能,并确定最优复配配方,利用气相色谱法对最优复配防霉剂的主要化学成分进行定性分析。结果 牛至、柠檬草及丁香精油对黑曲霉的最低抑菌体积分数分别为0.05%,0.1%,0.2%,对草本枝孢霉的分别为0.05%,0.1%,0.2%,对球毛壳菌的分别为0.025%,0.05%,0.1%;牛至和柠檬草精油的最佳体积比为1∶1,其分级抑制体积分数的指数值为0.75,表现为相加作用。结论 牛至与柠檬草精油复配后抑菌效果最为突出,且2种主要抑菌物质香芹酚和柠檬醛并未发生化学反应。     

复凝聚法制备磁性微胶囊及其磁响应特性

采用复凝聚法,以亲油改性的纳米Fe3O4为磁性颗粒,白油为分散介质,明胶、阿拉伯胶为壁材,在不同工艺条件下制备磁性微胶囊.通过激光粒度分析仪测试微胶囊的粒径及粒径分布,采用光学显微镜和扫描电子显微镜(SEM)观察微胶囊的表面形貌及分散状态,借助磁铁和振动样品磁强计(VSM)测试微胶囊的磁响应性能.结果表明,反应溶液pH=3.8、芯壁比1∶1时,微胶囊收率最高;搅拌速率为600r/min时,微胶囊的粒径分布最均匀;在pH=3.8、芯壁比1∶1、搅拌速率600r/min条件下制备的微胶囊形状规整性及单分散性好,且囊壁透明、表面光滑,具有良好的磁响应性能,可应用于磁泳显示和靶向药物传输领域.     

微胶囊化植物精油在果蔬保鲜包装中的应用

植物精油的天然抑菌性和抗氧化活性使其在果蔬保鲜领域有着广泛的应用前景。然而,植物精油具有强烈气味、易挥发等缺点,应用效果不佳。微胶囊技术可以掩盖精油的强烈气味,保持其化学稳定性,且具有缓释效果,可以更好地发挥植物精油在果蔬保鲜包装方面的优良性能。介绍了植物精油的抑菌活性、抗氧化活性以及植物精油微胶囊的芯材、壁材和常用的制备方法,对植物精油微胶囊保鲜剂控释包装、复合保鲜薄膜包装和可食性涂膜包装在果蔬保鲜包装方面的研究现状进行综述,以期为微胶囊化植物精油在果蔬保鲜包装方面的进一步研究与应用提供参考。     

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