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。     

芯材表面修饰法制备聚脲石蜡相变微胶囊及其表征

采用芯材表面修饰法制备了聚脲石蜡相变微胶囊。首先在固体石蜡颗粒表面引入氨基(-NH2),制备表面氨基修饰的固体石蜡芯材,再加入2,4-甲苯二异氰酸酯(TDI)和改性胺固化剂,形成聚脲壁包覆芯材。用差示扫描量热仪、傅里叶红外光谱仪(FT-IR)和激光粒径分布仪表征了芯壁用量比以及搅拌速度对相变微胶囊结构和性能的影响。FT-IR测试结果表明,该方法成功地在固体石蜡微球的表面引入了氨基。固定转速时,随着芯壁用量比中TDI用量的增加,微胶囊相变潜热明显增加;在十八胺与TDI摩尔比相同的条件下,随着芯材制备搅拌速率的增大,微胶囊的平均粒径减小而相变潜热明显增加。当搅拌速率为800 r/min,十八胺与TDI摩尔比为1∶2时,所制备的聚脲石蜡相变微胶囊包覆完整,热稳定性好,平均粒径为18.262μm,相变潜热可达142.8 J/g,包覆率达63%以上。     

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。     

广藿香油缓释微胶囊的制备及其性能分析

以广藿香油为芯材,壳聚糖和阿拉伯胶为壁材,采用复凝聚法对广藿香油进行包埋,制备广藿香油微胶囊。利用扫描电子显微镜、激光粒度仪、红外光谱和紫外光谱等分析方法研究各因素对微胶囊形成的影响。确定制备广藿香油微胶囊的最佳条件:采用中低粘度的壳聚糖,壳聚糖浓度为0.5%,阿拉伯胶浓度为4%,芯壁比为1∶2,复凝聚pH值为4.5,搅拌转速为2000r/min。红外光谱分析表明广藿香油包埋成功,其载药量和包封率分别为20.75%和67.2%。微胶囊缓释性能测试结果表明微胶囊具有良好的缓释效果,在25℃条件下,微胶囊释放150h后,累计释放率为33%,即微胶囊保留率为67%。     

三氯蔗糖微胶囊的制备与工艺优化

为延缓三氯蔗糖甜味特性,采用微胶囊技术对三氯蔗糖进行包埋处理。选择大豆分离蛋白和海藻酸钠为壁材,三氯蔗糖为芯材,采用复合凝聚法制备三氯蔗糖微胶囊。以微胶囊产率为评价指标,利用单因素试验和响应面优化法确定最佳制备条件,并对其形态等进行表征。研究结果表明,微胶囊的最佳制备工艺：复凝聚pH值为3.01,芯壁质量比为1.27,大豆分离蛋白和海藻酸钠的质量比为3.01,壁材质量浓度为0.0304 g/mL。按此工艺条件制备的三氯蔗糖微胶囊呈完整球形,表面光滑平整,粒径约为50μm,产率可达75.19%。     

三聚氰胺-甲醛相变微胶囊制备及性能

以三聚氰胺-甲醛树脂(MF)为壁材,石蜡为芯材,通过原位聚合法制备了芯壁比分别为2∶1、3∶1、4∶1的相变微胶囊,并对微胶囊进行了傅里叶变换红外光谱(FT-IR)、扫描电镜(SEM)、差示扫描量热分析(DSC)、热重分析(TG)及热循环测试。结果表明,在制备过程中,微胶囊的壁材不与芯材发生反应,制备的微胶囊为比较完整的球形。当相变微胶囊芯壁比为4∶1时,潜热值高达到162.7 J/g,与计算值非常接近,经过100次热循环后潜热值损失3.63%;当芯壁比较小时,微胶囊的耐热性及包裹较好。     

牛至精油微胶囊包埋工艺及抑菌效果的测定

目的制备牛至精油微胶囊,以提高牛至精油的稳定性。方法选取明胶和阿拉伯胶作为壁材,采用复凝聚法制备牛至精油微胶囊,并利用单因素实验和正交实验优化其工艺条件,同时研究牛至精油微胶囊的抑菌效果。结果牛至精油微胶囊化最佳的工艺条件,芯壁质量比为3︰1,反应p H值为4.5,乳化剂WJE-880的添加量为0.1%,以6000 r/min高速剪切2 min,在55℃,250 r/min的条件下搅拌固化60 min。此工艺条件下包埋率可达到83.1%。结论牛至精油经微胶囊化后显著地提高了其抑菌的持久性。     

响应曲面法橄榄油微胶囊化工艺优化研究

目的通过响应曲面试验确定制备橄榄油微胶囊的最佳工艺。方法以大豆分离蛋白和黑木耳多糖为新型壁材,橄榄油为芯材,亚麻籽胶为乳化剂,采用乳液聚合-冷冻干燥法制备橄榄油微胶囊,其实验指标为包埋率,并利用透射电镜观察微胶囊的形态。结果在固形物质量分数为15.4%、壁芯材体积比为5︰1、乳化剂的质量分数为0.24%的条件下,包埋率可达到77.22%。通过透射电镜观察微胶囊形态可知,橄榄油微胶囊基本呈圆球形,分布均匀,包埋效果较好。结论响应曲面试验可以很好地对橄榄油微胶囊的制备工艺条件进行优化,制备的橄榄油微胶囊对橄榄油的抗氧化作用有着加强效果。     

脂肪酸相变材料的封装制备及热工性质

本研究旨在解决能源供需在时间、空间和强度上的不匹配问题,以及单一相变材料存在的不足。采用原位聚合法制备了以月桂酸-肉豆蔻酸-棕榈酸-硬脂酸(LA-MA-PA-SA)四元低共熔脂肪酸为芯材,三聚氰胺改性酚醛树脂为壁材的复合相变微胶囊。通过扫描电子显微镜(SEM)、差示扫描量热仪(DSC)、傅里叶变换红外光谱仪(FT-IR)及热重分析仪(TG)对微胶囊进行表征。结果表明:当酚醛树脂预聚体合成的p H值为8～9、乳化剂为Span 60与Tween 60以质量比3∶7复合而成、胶囊化过程中搅拌速度为600 r/min及芯材与壁材质量比为1.37∶1时,所制备的微胶囊表面光滑、粒径分布均匀、包裹率较高,其相变温度和熔融潜热分别为32.93℃和87.67 J/g。微胶囊的芯材与壁材仅为简单的物理嵌合,且经过50次冷热循坏后,具有良好的储热性能和热稳定性。     

反溶剂法制备肉桂醛/乙基纤维素微胶囊及其表征

采用反溶剂法,以肉桂醛为芯材,乙基纤维素(EC)为壁材制备肉桂醛微胶囊,研究了不同芯壁比对微胶囊包埋率及形貌的影响;采用扫描电镜对所得微胶囊的表面形貌进行观察,借助红外光谱和热重分析等对其形成机理能进行了分析,并对其缓释性进行了测试。结果表明,当芯壁比为1∶3时包埋率最大,达到83%,载药量为21%,微胶囊为分散性好、粒径200 nm~1μm的球形粒子。红外光谱、热重分析结果表明EC可以通过自组装将肉桂醛包裹于其形成的疏水性空腔内部。微胶囊存放7 d后,其中的肉桂醛释放率仅为23%,而肉桂醛混合物中肉桂醛的释放率达到了54%,表明肉桂醛微胶囊具有一定缓释性。     

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.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

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.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

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.……     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.