超高压作用下扇贝闭壳肌色差变化探析

为了提高超高压作用下扇贝的感官品质,检验超高压作用的保鲜效果,对扇贝闭壳肌的色泽变化进行了研究。利用色差计对不同超高压处理条件下的扇贝闭壳肌的a~*、b~*、L~*和ΔE进行测定,找到最优的超高压试验条件,利用Design Expert软件进行试验设计,并对试验参数进行优化,得出扇贝闭壳肌超高压处理的最优参数。通过试验得出,当试验压力为206 MPa、保压时间为100 s时,扇贝闭壳肌的红度值a~*为-5.01、蓝度值b~*为-12.19、亮度值L~*为67.12、总色差ΔE为11.61,与扇贝的初始值比较接近。在超高压的作用下,扇贝闭壳肌的色泽得到了有效改善,闭壳肌的亮度也显著提高,为超高压技术在扇贝加工领域的应用提供了理论基础。     

应用圆二色光谱研究真空对超氧化物歧化酶二级结构的影响

超氧化物歧化酶经真空处理不同时间,利用圆二色光谱研究不同真空时间对超氧化物歧化酶二级结构的影响.结果表明:在3～15 min范围,不同真空处理时间对超氧化物歧化酶的α-螺旋、β-折叠、β-转角及无规卷曲相对含量的影响程度不同.与对照组相比,处理组的α-螺旋、β-转角和无规卷曲含量降低,降幅范围分别为26.1%～41.3%、52.1%～68.8%和2.1%～3.8%;β-折叠增加,增幅范围分别为6.5%～9.2%,表明真空作用使超氧化物歧化酶的二级结构中α-螺旋、β-转角及无规卷曲向β-折叠转化.     

不同真空处理时间对辣根过氧化物酶二级结构的影响

辣根过氧化物酶经真空处理不同时间,利用圆二色光谱研究不同真空处理时间对辣根过氧化物酶二级结构的影响。结果表明:在3~15 min时间内,不同真空处理时间对辣根过氧化物酶的α-螺旋、β-折叠、β-转角及无规卷曲相对含量产生不同程度的影响,但是影响程度较小,表明辣根过氧化物酶二级结构相对力学作用具有较高的稳定性。     

还原法羽毛角蛋白再生材料二级结构的差异解析

建立一种解析还原法羽毛再生材料中蛋白质二级结构差异的方法。对降解所得不同形式角蛋白再生物进行傅里叶变换红外光谱的测试,通过对其酰胺III带的分析,确定在羽毛的再生过程中所得的两种不同形式的降解物(角蛋白溶液和角蛋白凝胶)的二级结构的差异。实验证明:在角蛋白溶液中,α-螺旋占优势,含量在β-折叠之上;而在角蛋白凝胶物中,β-折叠占优势,说明这种结构的角蛋白分子之间更容易生成氢键等物理交联,在一定的环境条件,促使形成致密的角蛋白交联物。该法快速、有效、稳定和敏感,适用于检测还原法羽毛角蛋白再生材料二级结构。     

可膨胀石墨/三聚氰胺甲醛树脂核-壳结构粒子的合成与无卤阻燃的应用

通过在可膨胀石墨(EG)表面原位引发三聚氰胺甲醛树脂(MF)缩聚反应成功制备出一种新型核-壳结构阻燃粒子。红外光谱(FT-IR)及扫描电镜(SEM)分析表明,MF在EG表面形成了完善的包覆结构,有效提高了EG的阻燃性能。10%质量分数核-壳结构粒子的引入即能显著提高硬质聚氨酯泡沫的阻燃性能并保持良好的力学性能和绝热性能;完善的MF包覆壳层对EG阻燃性能的提高、与基体界面的改善作用以及不利导热作用的有效屏蔽是该综合性能提高的主要原因。     

有机汞化合物对木瓜蛋白酶的失活机理研究

复合食品包装材料残存的痕量重金属结合物严重威胁消费者健康。为了探明重金属结合物对生物大分子的影响及作用机理,研究了一定浓度的有机汞化合物（对氯汞苯甲酸,CMBA）使木瓜蛋白酶失活前后,该木瓜蛋白酶的结构变化。结果表明,经浓度为1×10-4 mol/L的CMBA处理后,木瓜蛋白酶的二级结构变化明显,其α-螺旋结构质量分数从43.4%急剧减少至4.2%,β-折叠、β-转角和无规卷曲质量分数从12.7%、16.0%和27.2%分别提高至40.0%、19.6%和36.2%,该酶二级结构成分由α+β型绝大部分转变为全β型。CMBA分子诱导木瓜蛋白酶L-链的α-螺旋结构趋向离散,构象松散,致使其天然构象遭到破坏,木瓜蛋白酶失活。经CMBA处理后的木瓜蛋白酶,其荧光光谱最大吸收峰红移7 nm,荧光强度降低显著,这是由色氨酸（Trp）残基被包埋在极性亲水环境下引起的。分子对接结果表明CMBA结合到木瓜蛋白酶的疏水活性口袋内,可与其中的甘氨酸（Gly）66形成氢键,与Trp26形成疏水键,该结果与光谱分析结果相一致。     

人工角蛋白膜的成分及致密性表征

将羊毛溶解制得人工角蛋白膜,采用紫外、红外、拉曼光谱和扫描电镜表征其组分及致密性.实测结果表明,人工角蛋白膜对紫外光具有强吸收能力;角蛋白膜中大分子的构象以β-折叠链为主,与羊毛大分子的构象以α-螺旋链为主不同;膜的拉曼光谱也进一步解释和印证了羊毛角蛋白在经过溶解再固化过程后二级结构的变化;扫描电镜形态观察证明该成膜法制得的角蛋白膜为致密膜.     

再生丝素/丝胶共混蛋白水溶液的静电纺丝

采用静电纺丝方法制备了再生丝素/丝胶共混纤维,分析了共混配比对再生丝素/丝胶水溶液流变性能和静电纺可纺性的影响,通过扫描电镜、拉曼光谱和DSC等手段研究了所得纤维的形态和微细结构及其力学性能。研究结果表明:随着溶液中丝胶含量的增加,体系的表观粘度增大,静电纺纤维的直径减小且直径分布变窄;并且丝胶的存在有利于丝素蛋白从无规卷曲或α-螺旋结构向β-折叠结构转变,由此可提高静电纺纤维的力学性能。     

不同剪切速率下高浓度再生丝素蛋白水溶液性质与结构的研究

主要研究了不同剪切速率下,丝素蛋白浓度、pH值、钙离子和丝胶含量对高浓度再生丝素蛋白水溶液性质的影响,并采用偏光显微镜和拉曼光谱对剪切前后的溶液结构进行了观察分析.结果表明,高浓度再生丝素蛋白水溶液经过一定的剪切作用后呈现出各向异性的特点,且随着各种因素的调节,溶液出现各向异性的临界剪切速率也随之改变.同时,在一定的剪切条件下,高浓度再生丝素蛋白水溶液中的丝素蛋白分子可发生由无规卷曲向α-螺旋构象的转变,并有进一步形成β-折叠构象的趋势.     

含氟丙烯酸酯单体的合成及固化膜的性能

以六氟环氧丙烷低聚物和(甲基)丙烯酸-β-羟乙酯为起始原料,合成了(甲基)丙烯酸-β-(全氟烷氧基酰基)乙酯四种新型含氟单体,其结构经红外光谱(FT-IR)、核磁共振(1H-NMR和19F-NMR)确证。初步考察了上述单体对丙烯酸酯类紫外光固化涂料的改性作用,结果表明,提高含氟组分比例对固化膜的初始水接触角影响较小,但经过加热后处理可显著增强固化膜的疏水性。由此推断,热处理能有效促进含氟侧基向表面迁移,且含氟侧链越长,这种向空气界面富集的倾向尤为明显。当含氟组分占涂料配方的4%～6%(质量分数,下同)时,固化膜的最大水接触角可达到120°。     

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 ...