猪肉新鲜度指示卡的研究

研究了一种能够根据包装内猪肉腐败程度而显示不同颜色的指示卡,用于指示猪肉的新鲜度。 将浓度为 0. 2% ,0. 3% ,0. 4% ,0. 5% 的溴甲酚紫乙醇溶液,分别与浓度为 0. 7% 的羟丙基甲基纤维素溶液混合,经流延成膜后再与白色防水纸复合,制得了 4 种新鲜度指示卡,分别用于指示浅盘包装内猪肉的新鲜度。 在贮存期内,测定了猪肉中挥发性盐基氮的含量和对应的新鲜度指示卡颜色的 Lab 值,计算了新鲜度指示卡的色差值。探讨了溴甲酚紫含量对新鲜度指示卡准确显色的影响。 结果表明,新鲜度指示卡色差值与猪肉挥发性盐基氮含量呈线性相关。 在猪肉发生腐败时,溴甲酚紫溶液浓度为 0. 5% 的新鲜度指示卡(A4)由黄色变为绿色,变色点明显;继续腐败时,变为蓝色,变色梯度大;变色不受猪肉质量的影响,起到了指示包装猪肉新鲜度的作用。     

猪肉包装用新鲜度指示卡研究

选用溴甲酚紫为指示剂,制备了一种应用于冷鲜猪肉包装的新鲜度指示卡。将制备的新鲜度指示卡置于50,100,150 g 3种不同质量的猪肉包装中,由挥发性盐基氮表示猪肉的新鲜程度,色差与感官评定分数标示指示卡的颜色变化,观察猪肉的新鲜程度与指示卡颜色变化的相关性,从而判断指示卡的有效性。试验结果表明,所制备的新鲜度指示卡色差变化与猪肉挥发性盐基氮变化呈线性关系,并且不受包装猪肉质量的影响;当猪肉新鲜度降低到一定程度时,指示卡由黄色变为绿色。因此,所制备的新鲜度指示卡可以用于指示包装猪肉的新鲜程度。     

基于改性玫瑰茄花青素的新鲜度指示膜研制及其在鲳鱼包装中的应用

目的将一种基于改性玫瑰茄花青素的新鲜度指示膜用于鲳鱼保鲜包装,并对指示膜的新鲜度指示效果进行评价。方法以酰化改性玫瑰茄花青素为新鲜度指示剂,聚乙烯醇为涂布液基质,聚丙烯为基膜,制备新鲜度指示膜,研究其对挥发氨的响应性;以鲳鱼为研究对象进行包装应用试验。结果随着挥发氨浓度的增大,指示膜颜色由红变紫再变绿;鲳鱼由新鲜级变为次新鲜级直至腐败级时,指示膜颜色均发生变化,具有与鲳鱼样本品质较强的关联性;指示薄膜颜色变化主成分得分呈明显的聚类趋势,与样本新鲜级相对应;基于偏最小二乘回归的TVB-N模型能有效预测鲳鱼的TVB-N值。结论新鲜度指示膜具有用于鱼类产品新鲜度检测的潜力。     

负载蓝莓花青素的壳聚糖基智能指示膜监测花蛤新鲜度的研究

目的 研发一种可视化的新鲜度指示薄膜，探究其在花蛤新鲜度监测中的可行性。方法 以对pH敏感的蓝莓花青素为指示剂，壳聚糖为基质，通过复合明胶、乳酸链球菌素（Nisin）和迷迭香精油制备5种智能指示膜，研究其pH敏感性、颜色响应性、微观结构、阻隔特性、力学性能、含水率、水溶性、抗氧化、抗菌等特性。结果 蓝莓花青素溶液在pH值为3～12内颜色响应明显。随着膜组分的增加，薄膜微观结构的粗糙度增加，而水蒸气阻隔性能逐渐降低。Nisin和迷迭香精油的添加显著增强了抗氧化和抗菌能力。壳聚糖/Nisin/迷迭香精油–蓝莓花青素（CSNR–ATH）膜的紫外线阻隔性能较优而水溶性低。CSNR–ATH膜在花蛤的冷藏过程中能灵敏反映花蛤新鲜度的变化，复合指示膜由淡绿色变为黄绿色。结论 负载蓝莓花青素的壳聚糖基智能指示膜为花蛤新鲜度的监测提供了一种新的选择。     

乙基纤维素/蓝莓花青素浸泡型标签对牛奶新鲜度的指示

目的 旨在研发一款可浸泡在液体中的食品级牛奶新鲜度指示标签,让消费者简单方便且直观地了解牛奶的实时品质。方法 以乙基纤维素为聚合物基材,蓝莓花青素为pH敏感染料,吐温80和甘油为增塑剂制备出标签。通过比色分析、溶胀率、迁移测试、接触角、傅里叶变换红外光谱分析、扫描电镜(SEM)对指示标签进行表征,再将标签用于牛奶新鲜度监测,探究牛奶菌落总数、pH与指示标签总色差的关系。结果 花青素添加量为乙基纤维素质量分数10%的指示标签在pH缓冲液中的指示效果最佳;乙基纤维素和花青素通过氢键较好地结合使标签耐水性较好,可浸泡于液体中;迁移测试证明标签与牛奶接触不会造成安全问题;牛奶菌落总数、pH值与指示标签总色差存在相关性。结论 花青素添加量为乙基纤维素质量分数10%的指示标签在新鲜牛奶中显示为浅紫色,在变质牛奶中显示为粉色。该浸泡型指示标签在指示牛奶新鲜度上有良好应用价值和开发前景。     

负载桑葚花青素的葛根淀粉/壳聚糖复合膜的制备与表征

目的 研究桑葚花青素（Mulberry Anthocyanins, MA）添加量对葛根淀粉/壳聚糖复合膜理化性质及功能活性的影响。方法 以葛根淀粉和壳聚糖为成膜基材，MA为指示剂，采用流延法制备一种新型可食pH指示膜，测定葛根淀粉/壳聚糖复合膜的物理性能、抗氧化性、pH指示等性质，并将指示膜用于猪肉保鲜及新鲜度检测研究。结果 通过对添加不同MA含量的复合膜进行性能测试，发现MA和葛根淀粉之间氢键的形成，极大地改善了复合膜的拉伸强度。MA的加入使得成膜厚度、不透明度、拉伸强度（Tensile Strength,TS）、水蒸气透过率（Water Vapor Permeability,WVP）显著提高，断裂伸长率（Elongation At Break,EAB）显著降低。此外，MA增强了复合膜的抗氧化性和pH敏感性，MA-4的DPPH自由基清除率达到最大值85.24%。将复合膜应用于猪肉新鲜度检测，与对照组相比，负载MA的复合膜可抑制猪肉pH值和TVB-N值，并产生肉眼可辨的颜色变化，其中MA-3的颜色变化最为敏感。结论 加入一定量MA的复合膜能够改善其拉伸强度、不透明度、pH敏感性和抗氧化...     

冷鲜肉新鲜度指示标签的研究及应用进展

目的探究新鲜度指示标签在冷鲜肉包装领域的研究现状及应用进展,为新鲜度指示包装的应用提供理论基础。方法介绍新鲜度指示标签的定义和功能,并根据生鲜肉类腐败过程中产生的不同特征反应物进行分类,阐述不同类型指示标签的工作原理。探究新鲜度指示智能标签在国内外的研究现状及应用,并分析制约智能指示标签发展的因素。结论新鲜度指示标签在一定程度上代表着智能标签的发展程度,是食品包装未来发展的研究热点和方向之一;由于成本高、制作工艺复杂等因素的影响,国内还没有达到商业化程度,还需从技术角度继续深入研究,以开发出低成本、高精度的新鲜度指示标签,进而推动智能标签的商业化应用。     

壳聚糖/花青素复合薄膜的制备及鱼肉新鲜度监测

目的 研发一种指示效果快速准确且无毒无害的指示薄膜,这种可视化食品新鲜度指示包装可以让消费者更加便利地观察食品的新鲜度情况。方法 以具有生物降解性能的壳聚糖为成膜基材,以甘油为增塑剂,通过添加不同质量分数的花青素天然色素粉末作为指示剂,基于流延法制备具有酸碱指示作用的复合薄膜。通过改变薄膜中花青素的质量分数来调控指示薄膜在不同pH溶液及酸碱气氛中的显色性能。结果 当花青素粉末的质量分数为0.3%时,薄膜在pH=1.68～12.45溶液中颜色的变化最为明显,颜色由粉红色变为棕黄色;在盐酸气氛中则呈现蓝紫色,在氨水气氛中呈现棕黄色。将制备的指示薄膜置于装有新鲜鱼肉的玻璃瓶中,根据鱼肉的腐烂变质情况,薄膜能很快地发生变色反应。结论 鱼肉释放的某种碱性物质会促使花青素分子结构发生变化,根据鱼肉的腐烂变质情况,薄膜能很快地发生变色反应,可以实现鱼肉新鲜度的实时可视化监测。     

改性花青素涂覆聚丙烯新鲜度指示膜的制备与研究

以乙酸为酰化剂对玫瑰茄花青素改性处理制得新鲜度指示剂,选用聚乙烯醇(PVA)为基液,与改性花青素共混制得新鲜度指示液,以聚丙烯(PP)为基膜采用旋涂法制备食品新鲜度指示膜。对改性花青素进行红外光谱及紫外-可见光光谱分析,对指示膜pH响应性、热稳定性和光照稳定性进行了研究。结果表明,红外光谱显示玫瑰茄花青素成功引入酰基;紫外-可见光谱显示改性后的花青素溶液在可见光区域最大吸收峰下的吸光度突变区间由pH值2～3迁移到pH值3～4;指示膜pH响应测试显示随着pH值升高指示膜由红变浅粉再变绿;所制备改性花青素指示膜在光照和不同温度下的颜色稳定性均高于未改性花青素指示膜。     

基于玫瑰茄色素的鱼肉新鲜度指示标签

目的选用玫瑰茄提取的色素作为p H指示剂,制备一种用于鲜白花鱼新鲜度检测的指示标签。方法将质量分数为2%的玫瑰茄乙醇溶液分别取1,3,5,7,9 m L加入50 m L壳聚糖-淀粉成膜液中,制得5组食品新鲜度指示标签,分别贴于在3组4℃温度下进行保存的100 g新鲜鱼肉表面,并利用食品保鲜薄膜对鱼肉和托盘进行密封包装。通过以24 h为1周期对鱼肉的挥发性盐基氮、p H值和鱼肉的气味、外观、肌肉组织等感官变化情况进行检测与评价,并对食品新鲜度指示标签的颜色进行测定以及感官评价。结果膜液中的玫瑰茄色素溶液添加量达到7 m L时,指示标签由紫红变为灰绿,并在实验后期颜色逐渐向绿色靠近,颜色变化明显。结论玫瑰茄色素可用于鱼肉新鲜度检测,指示效果较好。     

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...     

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.     

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.     

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.……     

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.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

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.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.