海藻糖涂膜对鲜切苹果品质的影响

目的为了抑制鲜切苹果发生酶促褐变,改善其口感,延长其保质期。方法以富士苹果为实验材料,研究质量分数不同(0%,0.1%,0.5%,1%,5%)的海藻糖涂膜剂处理对鲜切苹果的保鲜效果,并测定褐变指数、Vc含量、SSC含量、可滴定酸含量、MDA含量等指标。结果采用海藻糖涂膜剂处理鲜切苹果的最佳质量分数为1%,可显著提高其品质。经质量分数为1%的海藻糖处理鲜切苹果后,其色泽口感俱佳,褐变抑制作用较强,明显降低了褐变指数和MDA的增长率,延缓了Vc、SSC和可滴定酸等含量的下降。结论海藻糖涂膜处理不仅可以抑制鲜切苹果在贮藏期间的褐变进程,而且还可以赋予其更好的风味,提高产品的品质,延长其保质期,对鲜切果蔬的保鲜研究具有重要意义。     

不同真空包装材料对鲜切甘薯品质的影响

目的 研究不同真空包装材料对鲜切甘薯品质的影响,筛选出保鲜效果最佳的真空包装材料。方法 本实验以厚度为0.01 mm的聚乙烯（PE）保鲜膜塑料薄膜+托盘为对照（CK）组,以聚酯镀铝膜（VMPET+PE）、铝塑复合、聚酯和高聚合尼龙面料复合聚乙烯（PA+PE）等4种真空包装材料为处理组,将鲜切甘薯置于4℃下避光贮藏16 d,研究其感官指标、营养物质含量及褐变相关酶等指标的变化。结果 在贮藏末期,真空处理的质量损失率及褐变指数分别约为CK组的28.6%和59.9%,且在短期内真空包装可明显推迟呼吸高峰的出现,抑制木质化现象的发生及酚类物质和丙二醛（MDA）的积累,减缓褐变相关酶活力的增强,维持淀粉等营养物质含量。结论 真空包装有利于抑制鲜切甘薯的生理生化反应,减缓营养物质消耗和有害物质的积累,维持其感官品质。     

热水处理对预包装鲜切马铃薯品质的影响

目的研究不同热处理时间对预包装鲜切马铃薯品质的影响。方法采用60℃热水对预包装鲜切马铃薯进行处理,时间分别为0.5,1.0,1.5 min。测定贮藏中的亮度L*值,颜色饱和度C*值,细胞膜透性,多酚氧化酶(PPO)和过氧化物酶(POD)活性,感官品质等指标,并进行比较分析。结果在温度为4℃的保存条件下,60℃热水处理1 min能较好地维持鲜切马铃薯的白度,保持细胞膜的完整性,抑制PPO和POD的活性,延缓鲜切马铃薯的褐变。结论热水处理可以改善鲜切马铃薯的品质,1 min热水处理组贮藏至第6天时仍具有良好的商品品质。     

鲜切香芋不同包装处理的贮藏效果及其生化变化

以粤北北乡香芋为试材,研究鲜切香芋在不同包装材料下的贮藏效果及生化变化.结果表明,在4℃贮藏温度下,与对照(普通塑料薄膜包装)、聚乙烯塑料薄膜(PE)包装相比,贮藏的前12天,真空包装(VP)能较好地保持鲜切香芋的可溶性固形物含量(TSS)和淀粉含量,褐变度、丙二醛(MDA)含量和多酚氧化酶的活性较低,而超氧化物歧化酶活性较高.随着贮藏时间延长,聚氯乙烯塑料薄膜(PVC)包装的鲜切芋头,酚类物质含量及丙二醛(MDA)含量低于其他包装,超氧化物歧化酶(SOD)活性最高,TSS和淀粉含量、多酚氧化酶(PPO)活性与VP处理的接近.总体看来,VP处理适合鲜切芋头的短期低温贮藏,PVC包装适合鲜切芋头的较长期贮藏.     

褪黑素对鲜切梨抗氧化系统和NO合成的影响

目的研究外源褪黑素处理对鲜切梨抗氧化系统及一氧化氮合成途径的影响。方法以“皇冠”梨片为实验材料,分别在0,50,100,150μmol/L褪黑素中进行浸泡处理。结果与对照组相比,褪黑素处理提高了鲜切梨的色差值,降低了鲜切梨呼吸作用、乙烯跃变高峰以及可溶性固形物含量,同时降低了鲜切梨中的菌落总数、霉菌数和酵母菌数。褪黑素处理抑制了多酚氧化酶和过氧化物酶的活性,提高了过氧化氢酶的活性,同时也显著提高了鲜切梨抗坏血酸过氧化物酶活性和超氧化物歧化酶活性,从而降低了活性氧含量。褪黑素处理提高了氧化型谷胱甘肽与还原型谷胱甘肽的含量比例,抗坏血酸与脱氢抗坏血酸的含量比例,同时还提高了谷胱甘肽还原酶活性、单脱氢抗坏血酸还原酶活性以及脱氢抗坏血酸还原酶活性。在外源施加褪黑素后,鲜切梨的硝酸还原酶活性和亚硝酸盐含量与对照组相比变化不明显,一氧化氮合酶活性和L-精氨酸含量得到明显提高。结论经100μmol/L的褪黑素处理对鲜切梨的抗氧化和保鲜效果最为显著,是一种较好的抑制鲜切梨褐变及保持鲜切梨品质的方法。     

鲜切山药保鲜护色研究

目的利用家用调味剂(蔗糖、食盐、白醋)对鲜切山药保鲜护色进行研究。方法利用L9(34)正交试验配置一定浓度的蔗糖、食盐、食醋复合浸渍液,并用聚乙烯薄膜进行包装,得出比较理想的鲜切山药贮藏方法。结果蔗糖、食盐、白醋都有很好的保鲜护色效果,单因素试验表明,当采用蔗糖、食盐、食醋(质量浓度分别为3,1,3 g/L)浸泡鲜切山药10 min后,其褐变度的减缓和PPO活性的抑制最为明显。正交试验结果表明,采用蔗糖、食盐、白醋质量浓度分别为4,2,3 g/L混合处理液浸泡10 min后,护色保鲜效果最好。结论经过特定浓度复配的蔗糖、食盐、白醋溶液能有效抑制鲜切山药的酶促褐变,起到保鲜护色的作用。     

1-MCP处理对早晚熟枇杷鲜果采后生理效应的影响

目的研究气调保鲜包装结合1-甲基环丙烯(1-Methylcyclopropene,1-MCP)处理对枇杷采后生理效应的影响。方法以早晚熟"白玉"、"丰玉"枇杷为实验材料,采用1-甲基环丙烯对其进行处理,再使用气调保鲜包装(厚度35μm),将其在冷藏温度为(6±1)℃的条件下贮藏,观察其采后生理变化特性及不同品种之间的贮藏性能差异。结果 1-MCP处理可抑制枇杷果实硬度、可溶性固形物含量和可滴定酸含量的下降,延缓枇杷的褐变、过氧化物酶(Peroxidase,POD)活性的上升,减少枇杷的腐烂率,促进枇杷果实多酚氧化酶活性(Polyphenoloxidase,PPO)、脂氧合酶(Lipoxygenase,LOX)活性的下降。枇杷品种白玉的呼吸速率、POD、PPO活性及褐变指数较丰玉高,LOX活性和丙二醛(Malondialdehyde,MDA)含量增加明显,其硬度和营养成分含量较低;丰玉的腐烂率高于白玉。结论采用气调保鲜包装结合1-MCP处理延缓了枇杷在冷藏过程中营养物质的下降,进而延迟了枇杷褐变和衰老进程。其中早熟品种白玉枇杷的褐变发生率和膜脂过氧化程度更高。     

超声渗透等离子活化水对香蕉切片鲜切品质的影响

目的 利用等离子活化水处理香蕉切片不同时间,以达到对香蕉切片护色的目的,并探究贮藏期间的特性变化规律。方法 使用低温等离子体(Cold Plasma, CP)处理去离子水产生等离子活化水(Plasma Activated Water, PAW),超声辅助PAW处理香蕉切片后测定PAW处理对香蕉切片微观结构、贮藏性质、风味物质、酶促褐变关键酶及活性氧水平的变化。结果 与对照组相比,PAW处理增强了贮藏期间多酚氧化酶(Polyphenol Oxidase, PPO)和过氧化物酶(Peroxidase, POD)的活性;改善了切片的硬度、水分含量、色度值等贮藏特性。激光扫描共聚焦显微镜的荧光结果显示,PAW处理提高了切片细胞中活性氧(Reactive Oxygen Species, ROS)的水平。此外,气相色谱–质谱的结果表明,PAW处理增加了香蕉切片中酯类物质的百分比,而在处理后的香蕉切片中没有检测到醇类物质。由扫描电子显微镜表征可知,PAW处理影响了香蕉切片的表面微观结构,使香蕉切片表面变得粗糙并伴有损伤的出现。结论 香蕉切片在PAW–30 s处理下具有较强的抗氧化活性,较好的贮藏品质以及对风味物质和微观结构较小的影响。PAW对果蔬鲜切品质有积极作用,采用PAW–30 s对鲜切果蔬产品进行加工贮藏具有广阔的前景和更环保的经济效益。     

乙醇复合抗坏血酸处理对鲜切苹果贮藏品质的影响

目的 为了研究乙醇处理对鲜切苹果贮藏品质的保鲜效果。方法 以鲜切‘寒富’苹果为材料,比较乙醇、乙醇复合抗坏血酸（Vc）溶液处理对鲜切苹果在4 ℃下贮藏品质的影响。分析鲜切苹果包装内的气体成分变化、可溶性固形物含量、硬度、颜色、质量损失率等品质指标,还对组织衰老进程、酚类物质代谢和活性氧代谢及微生物数量进行评价。结果 研究表明,体积分数为30%的乙醇溶液浸泡鲜切苹果能有效保持冷藏货架期间果实的硬度、可溶性固形物含量、较低的质量损失率,延缓果实组织表面颜色变化和褐变的发生;进一步研究显示,乙醇可能是通过抑制酚类物质的氧化分解,从而减少了醌类物质在组织中的积累;乙醇处理还有利于抑制果实组织中电导率的升高,此外经乙醇处理后,大肠菌群和菌落总数均显著小于对照组和复合处理组中的数量。结论 采用乙醇处理鲜切‘寒富’苹果,有利于保持果实的品质,并延缓衰老和褐变进程,从而延长了货架期。     

含α-生育酚的PE/PVA活性包装膜对鲜切苹果品质的影响

目的研究含α-生育酚的聚乙烯/聚乙烯醇(PE/PVA)活性包装膜对鲜切苹果品质的影响。方法通过溶液-涂布法制备得到含不同浓度α-生育酚的PE/PVA薄膜,测定分析贮藏期间含不同浓度α-生育酚的PE/PVA薄膜对鲜切苹果的色泽、质量损失率、硬度、维生素C含量、可滴定酸含量以及多酚氧化酶(PPO)活性的变化。结果含α-生育酚的PE/PVA薄膜可以使鲜切苹果的褐变减缓,失重率增加,硬度、维生素C含量和可滴定酸含量下降,抑制了其PPO活性,随着包装膜中α-生育酚含量的增加,对鲜切苹果品质的保护效果越好。结论该活性包装膜可以减缓鲜切苹果的品质变化,证明向包装薄膜中添加抗菌剂、抗氧化剂等来达到延长食品货架期是有效的。     

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.     

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...     

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.     

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.     

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 ...