Lipid and Fatty Acid Composition of Selected Fungi Grown on Whey Medium

The molds Aspergillus nidulans, Penicillium frequentans, and Fusarium lycopersicum were tested for lipid production when grown on a deproteinized whey medium. F. lycopersicum produced highest total lipid (38.56%) followed by A. nidulans LC-1 (16.90%) and P. frequentans (10.53%). Triglycerides and phospholipids were the predominant components in the neutral lipid fraction followed by partial glycerides, free fatty acids and nonsaponifiable matter. Phospholipid content was highest in P. frequentans. Palmitic, stearic, oleic and linoleic acids were the major fatty acids and their relative concentrations varied among the three fungi. Lower chain fatty acids were absent.     

Thermal Destruction of Cysteine and Cystine Residues of Soy Protein under Conditions of Gelation

Thermal destruction of cysteine and cystine residues of soy proteins was investigated under gelation conditions. Significant cysteine and cystine were lost as a function of heating time. The rate and extent of loss was affected by heating temperature, pH, salt concentration and viscosity of the protein solution. Greatest effects were from heating temperature, pH and viscosity. A significant amount was lost even at pH 7.0 at 100°C. Amino acid analysis revealed that thermal destruction of cysteine and cystine at high protein concentration and near neutral pH did not result in formation of lysinoalanine. The results can be useful to preserve nutritional quality in thermal processing of soy proteins.     

指甲花萃取物对镍从瓦特镀液中电沉积的影响(英文)

采用赫尔槽试验、分散能力测定法、扫描电镜、X射线衍射、能谱分析、硬度测量及交流阻抗谱,研究指甲花萃取物(主要成分为2-羟基-1,4-萘醌)对镍从瓦特镀液中电沉积(以低碳钢为基体)的影响。在温度40~50°C和pH4.5~5.0的条件下,从含60mL/L指甲花萃取物的瓦特镀镍液中得到的镀层具有良好的耐蚀性和硬度。指甲花萃取物作为瓦特镀镍液的添加剂,极大地提高了镀液的分散能力和电流效率。在最佳指甲花萃取物浓度下所得的镀镍层为晶态,结晶细致。     

Tribological behavior of ultra-high molecular weight polyethylene in a hip joint simulator

In this paper effects of various injection molding parameters on tribological properties of ultra-high molecular weight polyethylene (UHMWPE) were investigated. The tribological properties like coefficient of friction and wear rate were obtained from the experimental results of hip simulator which was designed and fabricated in the laboratory. Bovine serum was used as a lubricant in this study. In addition, the hardness of the specimen was also investigated as well. The injection molding parameters that varied for this study are melt temperature, injection velocity and compaction time. The results show that contact loads and melt temperature were mostly influenced the tribological behavior of UHMWPE. A wear mechanism map was developed to study the dominant wear mechanism that influences the wear behavior of UHMWPE. SEM was employed to study the worn out morphologies of UHMWPE. The dominant wear mechanisms that are dominated through our study are ironing, scratching, ploughing, plastic deformation, and fatigue wear.     

Synthesis of Cost-Optimal Shell-and-Tube Heat Exchangers

Abstract

Synthesis of cost-optimal shell-and-tube heat exchangers is a difficult task since it involves a large number of parameters. An attempt is made in this article to simplify the process of choosing the parameter values that will minimize the cost of any heat exchanger satisfying a given heat duty and a particular set of constraints. The simplification is based on decoupling of the geometric and the thermal aspects of the problem. The concept of curves for cost-optimal design is introduced and is shown to simplify the synthesis process for shell-and-tube heat exchangers.     

化学镀镍槽热损失的最小化

在不使用电能的情况下,化学镀依靠含有还原剂的水溶液中金属离子的催化还原,从而实现金属的沉积.其成功与否,很大程度上取决于温度的维护.温度升高,沉积速度加快,因此,应当避免热量散失到周围环境中.本丈估算了包裹不同隔热材料的化学镀镍液的散热量.结果表明,采用棉花作为隔热材料,热损失可降至最低,从而提高并维持一定的沉积速率.     

Creep deformation and rupture behaviour of directionally solidified GTD 111 superalloy

The creep behaviour of directionally solidified (DS) Ni‐base superalloy GTD 111 has been investigated at various temperatures (649 °C to 982 °C) and stresses (124 MPa to 896 MPa). Specimens machined in longitudinal and transverse directions with respect to the grain orientation from three batches of the material were tested. The specimens in the longitudinal direction consistently exhibited higher creep rupture life and creep ductility than specimens from the transverse direction. There were some systematic variations in creep deformation and rupture behaviour among specimens from different batches. Optical and scanning electron microscopy investigations were conducted to understand the creep rupture behaviour. Various deformation and rupture models were evaluated for representing the creep behaviour of the alloy and a neural network model was applied to creep rupture data to assess its predictive capability.     

AZ31镁合金激光焊件的力学性能和应力腐蚀行为

采用Nd-YAG激光对AZ31 HP镁合金进行激光自熔焊接。显微组织分析表明,使用或不使用填料（焊料）AZ61镁合金得到的激光焊接接头的平均晶粒尺寸大约为12μm,显微硬度和拉伸强度与母材相近。然而,慢应变速率拉伸表明,在ASTM D1384溶液中两种焊接接头的抗应力腐蚀性能比母材略差。可观察到应力腐蚀裂纹在焊缝金属萌生并向热影响区（HAZ）扩展。然而,在以AZ61镁合金为填料（焊料）获得的焊接接头中,观察到裂纹起源及扩展出现在热影响区（HAZ）。在慢应变速率拉伸试验中,由于试样表面暴露在腐蚀环境中,在氢氧化镁/氧化镁层形成局部损伤,从而导致应力腐蚀裂纹的生成。     

IDENTIFYING GLOBAL/LOCAL INTERFACE BOUNDARIES USING AN OBJECTIVE SEARCH METHOD

One of the key components in computational mechanics procedures using global/local methods is the specification of the global/local interface. Global/local interfaces are usually specified by visually examining some measure of response such as colour-coded contour plots of stresses or strain energy. However, when both global and local domains are modelled in three dimensions, such a specification is not as obvious, and it lacks objectivity and uniqueness. An Objective Search Method (OSM) is presented to specify the global/local interface in three dimensions in a precise, repeatable and automated manner. The OSM performs the search incrementally in all directions in three dimensions radiating from a location of interest until certain generalized guidelines are satisfied and the global/local interface is identified. The OSM is suited to problems where localized phenomena exist but where their domains are not known a priori. The generalized guidelines for the OSM require the identification of nodes lying on the external surfaces of the model. As an important component of the OSM, a unique method to identify surface nodes has been developed and is also presented. Finally, the uniqueness, sensitivity and versatility of the OSM is illustrated using two example problems and the computational effort involved with the OSM is discussed in the context of a third example problem.