Gelation Properties of Ovalbumin as Affected by Fatty Acid Salts

The physicochemical properties of heat-induced ovalbumin (OVA) gels containing fatty acid salts (FAS) were investigated. Water-holding ability and transparency markedly increased in the presence of sodium caprate or sodium laurate. At 9% of the protein concentration transparent and hard gels formed; at 7%, transparent and soft gels formed. Scanning electron microscopy showed that the transparent gels had a more homogeneous structure than turbid gels without FAS. Differential scanning calorimetry indicated that denaturation temperature of OVA was decreased and the peaks became broader after addition of FAS.     

复杂结构ADC12铝合金汽车支架挤压铸造工艺参数优化

目的 解决ADC12铝合金汽车发动机支架在挤压铸造成形工艺下的缺陷问题。方法 利用ProCAST模拟软件对该汽车发动机支架的挤压铸造充型和凝固过程进行模拟,对挤压铸造工艺参数进行正交试验设计并模拟得到最佳工艺参数,对铸件浇注远端厚壁部位采取局部加压优化措施,并对厚壁部位进行X-Ray探伤,观察铸件的缺陷情况。结果 对挤压铸造的工艺参数进行正交试验极差分析后,发现各工艺参数按对铸件凝固后质量的影响程度从大到小的顺序依次为挤压比压、浇注温度、模具温度。通过正交试验得到优化后的工艺参数为浇注温度730 ℃、模具温度300 ℃、挤压比压150 MPa。局部加压时挤压销的最佳激活时间为4 s,此时可以完全消除铸件内部的缩孔缩松缺陷。选择优化后的工艺参数生产该汽车发动机支架,产品外观完整,没有出现表面裂纹等缺陷。在X-Ray探伤下无明显缺陷,内部质量良好。结论 选择合理的浇注温度、模具温度和挤压比压可以有效减少铸件内部的缩孔缩松缺陷,采用局部加压并合理控制挤压销的激活时间可以完全消除缩孔缩松缺陷。     

Spontaneous emission from a three-level atom placed in three-dimensional photonic crystals in the long-time limit

The paper describes the spontaneous emission from a three-level atom placed in a periodic dielectric microstructure which exhibits a complete three-dimensional photonic band gap. By using the Euler approach, the upper level population of the atom is calculated for a wide range of relationships between the Rabi frequency and the detuning of the atomic transition frequency from the upper band edge. The results indicate that there are three cases of the relationship between Rabi frequency and detuning, which determine distinctive states of the atomic population in the long-time limit. When the detuning is greater than the Rabi frequency, the upper level has a zero steady-state atomic population, which leads to enhancement of spontaneous emission. When the magnitude of the detuning is less than the Rabi frequency, the upper level has a nonzero steady-state atomic population, which leads to suppression of spontaneous emission. When the negative detuning is greater than the Rabi frequency, the upper level has a nondecaying oscillatory-state atomic population due to long-time atomic splitting. These three properties of the spontaneous emission are relevant to several optical devices on an atomic scale, such as optical memories, switches and clocks.     

Synthesis of a stabilizing control problem for a multimachine power system with phase shifter

A systematic procedure is considered for the synthesis of a stabilizing control method for a multimachine power system with phase shifter, taking into account the velocity governor. A new approach is presented, which uses a coordinate-transformation technique and an optimization technique. The application of this method to a stabilizing control problem for a power system is illustrated by considering a 3-machine power system with phase-shifter control, taking into account an additional control vector for the governing system with one time constant. The synthesized controls are then used to improve the power-system transient stability to a remarkable degree and to restore the power-system transients rapidly to the stable-equilibrium point. Numerical results arc given.     

An application of interpretive structural modelling to analyse preference structure in multiobjective dynamic environmental-economic systems†

This paper applies ISM (interpretive structural modelling) to analyse preference structure in a multiobjective problem of a dynamic environmental-economic model, and terms this method IPSM (interpretive preference structural modelling). Multi-objectives in the model include minimizing social cost of pollution, and maximizing total consumption in a planning interval. IPSM analyses decision-maker's preference relations (mental model) among many Pareto-optimal solutions of the multiobjective systems under the interactive cooperation between the decision-maker and the model-builder, and extracts the decision-maker's preference structure as a hierarchical directed graph, where the vertices of the graph correspond to the Pareto-optimal solutions and the directed edges correspond to the preference relations. An interesting economic interpretation for a preferred solution is discussed in terms of the economic interpretation of the discrete minimum principle.     

Decentralized adaptive control of robotic manipulators†

We develop a self-tuning-type adaptive control for robotic manipulators with six joints, and analyse the stability of the control system. In order to reduce the computational effort for obtaining the control input in real time, a decentralized adaptive control system is designed in which each joint of the manipulator is regarded as a subsystem and controlled independently in parallel. In this control system we regard the interaction among the multiple joints as an unknown input in each subsystem. The influence of the interaction on the stability of the overall control system is analysed using a Lyapunov function. The theoretical result obtained is that the control system is always stable in the sense that the error between the output of the adaptive predictor and the real output (angular velocity of each joint) will not exceed the amount of interaction. This result is verified by some simulation studies.     

Design of servo systems for distributed parameter systems by finite dimensional dynamic compensator

The design problem of servo systems for distributed parameter systems is investigated. The output regulator of integral type is designed in order to guarantee internal stability and output regulation. The design procedure based on a dynamic stabilizing compensator is discussed. The output regulation of a wide class of distributed parameter systems is proved under the condition that a closed-loop system is stabilized by a dynamic compensator of general type. Then a closed-loop system can be stabilized by a finite dimensional dynamic compensator under some additional conditions. The reducabitity of the design procedure to a purely finite dimensional one is discussed.     

Influence of Drying Methods on Volatile Sulfur Constituents of Caucas (Allium victorialis L.)

The effects of freeze-drying, hot air, and vacuum far infrared-drying on caucas (Allium victorialis L.) flavor was studied. The GC and GC-MS characterization of volatiles from dried caucas powders revealed the main flavor components; disulfides and trisulfides, as well as the antithrombotic substances; vinyldithiins, remained in all products. Vi-nyldithiins were isolated and subsequently confirmed by IR, NMR and Mass Spectrometry. Rehydration of the dried powders increased measurable volatile compounds, which were produced enzymatically. Increased-storage time decreased measurable volatiles in freeze-dried and hot air-dried caucas powders while the volatile profile remained unchanged.     

Heat-induced Gels of Rice Globulin: Comparison of Gel Properties with Soybean and Sesame Globulins

The hardness and water-holding ability of rice globulin gels were intermediate between those of gels of soybean and sesame globulins. Scanning electron micrographs showed that rice globulin gel had a rough network structure composed of small globular particles of protein aggregates. Effects of various reagents on solubilization of proteins from the three gel types were compared. Disulfide bonds and hydrophobic interactions contributed mainly to the stability of rice globulin gels. The contributions of disulfide bonds to both the formation and stability of rice globulin gels were greater than for sesame globulin gels.     

Heat-induced Gelation of Chicken Gizzard Myosin

Chicken gizzard myosin solution formed a gel when heated above 40°C. The rigidity of the gel was constant above 65°C. Maximum pH for gel formation was 5.9 at 0.6M and 5.7 at 0.15M KCl. Higher rigidity of the myosin gel was observed at low ionic strength than at high ionic strength. Rigidities of myosin at 0.6M KCl increased by (mg/mL)^2.5 and at 0.15M (mg/mL)^{1, 4} myosin concentration. The strength of gizzard myosin gels was comparable to that of myosin gels from chicken breast muscle under similar conditions.