The study on the preparation methods and the fluidity of large rare earth oxide particles

In this work large CeO₂ particles were prepared using H₂C₂O₄ and NH₄HCO₃ as precipitators. The effects of feeding mode and speed, stirring speed, aging time, precipitate and calcination temperature and precipitation method on physicochemical properties of CeO₂ were studied when the precipitator was H₂C₂O₄. By the NH₄HCO₃ precipitation method, the effects of adding inoculating crystals and additives on particle size, loose density and fluidity of CeO₂ were investigated. Under optimized conditions, large CeO₂ particles with high loose density and good fluidity of can be prepared by either H₂C₂O₄ or NH₄HCO₃ precipitation method. SEM also investigates the morphology of the particles prepared by both methods. The results show that physicochemical properties of CeO₂ particles prepared by the NH₄HCO₃ precipitation method are not as good as those of CeO₂ particles prepared by the H₂C₂O₄ precipitation method. However, both methods are suitable for industrial production due to their simple processes, low equipment investment and ease for industrial development. Our results show that large rare earth particle can be prepared by the optimized conventional methods. This study provided a useful method to prepare of large rare earth particles.     

Relationship between physicochemical properties and chemical stability of muramyldipeptide derivative B30-MDP in liposomal solutions

The muramyldipeptide derivative B30-MDP has immunoadjuvant activity and vesicle-forming ability in aqueous environments. It is therefore important to evaluate the relationship between its physicochemical properties and chemical stability for use as a vaccine adjuvant. We studied the effects of octyl--D-glucoside (O.G.) incorporation on the physicochemical properties and chemical stability in aqueous solution at pH 7.4. The changes in particle size and in the membrane fluidity of B30-MDP liposomes, which were induced by the addition of O.G., were measured to confirm the transition from micelle phase to vesicle phase. The degradation of B30-MDP in both liposomal and mixed micellar solutions was measured by reverse-phase high-performance liquid chromatography. This degradation occurred by a pseudo first-order reaction at 313, 323 and 333 K. The shelf-life of the B30-MDP solution supplemented with O.G. was approximately one-seventh of that of B30-MDP alone in the liposomal solution. The changes in thek _obs values of B30-MDP correlated well with those in membrane fluidity induced by O.G. incorporation. These results indicate that an increase in membrane fluidity labilizes B30-MDP in liposomal solution.     

水溶性聚合物改性水泥的研究I.水溶性聚合物改进水泥流动性

制备了水解聚丙烯酰胺（ＨＰＡＭ）、磺甲基化聚丙烯酰胺（ＳＰＡＭ）及磺化聚苯乙烯（ＳＰＳ）等几种水溶性聚合物。研究了水溶性聚合物的种类、阴离子度、分子量、表面活性、掺量、ｐＨ值等因素对水泥净浆流动性的影响。结果表明阴离子聚合物及适中的阴离子度、分子量、掺量、ｐＨ值有利于水泥的分散，从而改善水泥的流动性。聚合物的电荷保护作用是影响水溶性聚合物改性水泥分散的主要因素。提出了聚合物分散水泥粒子与分子链性质相关的作用机理。     

Sit-to-walk Task in Hemiplegic Stroke Patients: Relationship between Movement Fluidity and the Motor Strategy in Initial Contact

Purpose: Generally, stroke patients can walk and stand up fluidly but fulfill the sit-to-walk (STW) task with difficulty. The purpose of this study was to investigate the relationship between movement fluidity and motor strategy in the initial contact of the STW task. Method: Thirty stroke patients and ten healthy subjects performed the STW task from a sitting position, and their movement was measured by a motion analysis system. The differences in data between patients and healthy subjects were analyzed using the Mann-Whitney U test. The relationship between fluidity index (FI) and other indices (kinetic and kinematic data in STW, functional independence measure [FIM], and Fugl-Meyer Assessment [FMA]) were analyzed using Spearman''s rank correlation coefficient. Results: The stroke patients had lower FI values than the healthy subjects and exhibited shortened step length and prolonged duration from onset to the first stance leg off. FI values correlated with trunk flexure angle at initial contact, first step length, and maximum vertical floor reaction force. The independent level of the FIM of stair climbing and walking ability and the FMA of balance also correlated with FI. Conclusion: There is a possibility that poor balance is one of the reasons why stroke patients are unable to start walking fluently from the sitting position. To perform the STW fluidly, patients must start walking before the trunk extension is fully completed. The relationship between FI and indices of physical ability, namely stair climbing and balance, may have therapeutic benefits for coaching the STW task to stroke patients.     

Viscoelastic behavior of stock indices

The scattering diagram of a stock index results in a complex network structure, which can be used to analyze the viscoelastic properties of the index. The change along x- or y-direction of the diagram corresponds to purely elastic (or spring like) movement whereas the diagonal change at an angle of 45° corresponds to purely viscous (or dashpot like) movement. The viscous component pushes the price from its current value to any other value, while the elastic component acts like a restoring force. Four indices, namely, DJI, S&P-500, NASDAQ-100, and NASDAQ-composite were studied for the period of 2001-2009. NASDAQ-composite displayed very high elasticity while NASDAQ-100 displayed the highest fluidity in the time period considered. The fluidity of DJI and S&P-500 came out to be close to each other, and they are almost the same in the second half of the period.     

Response of gerbera jamesonii acrocarpous callus stimulated by mechanical vibration

Applying different mechanical vibrations, 2–3 Hz frequency, to stimulate the gerbera jamesonii acrocarpous callus, we found that it increases the growth rate and the content of soluble protein but decreases the fluidity of cell membranes. When the frequency was greater than 4 Hz, the effect was contrary to that of 2–3 Hz. In this paper, we also prove the double effects in the plant callus growth and explore the mechanism of the double effects in physical stimulation.     

Transport Properties of Alkali Fluoride High Temperature Ionic Liquids and Application of Theories of Viscous Flow

The transport properties of several alkali fluoride high temperature ionic liquids(LiF, NaF, KF, RbF and CsF) were studied in a range of 980-1400 K and the temperature dependences of the viscosity and density were interpreted, in agreement with the classical equations characterizing the viscous flow(Arrhenius, Batchinski, Eyring and Frenkel). The experimental results reveal the validity of these equations even at high temperatures, suggesting that no significant structural changes of alkali fluorides occurred in the studied temperature range. Our results clearly demonstrate that the mentioned thermo-physical properties can be used as powerful tools in the further investigations of the ionic interactions governing the alkali fluoride molten salts.     

流动注射氢化物石墨炉法测定鱼,香梨中的痕量汞

将流动注射仪与石墨炉进样装置联用，实现了汞的氢化物石墨炉测定。选择的最佳测定条件为涂金或涂钯普通石墨管，３ｍｏｌ／ＬＨＣｌ－０．３％ＫＢＨ４、载气流速９０ｍＬ／ｍｉｎ、测定时关闭石墨炉内气流，富集温度１５０℃，原子化温度７００℃。其特征质量为３４ｐｇ／０．００４４Ａ     

Study of thermal and chemical effects on cellulase enzymes: Viscosity measurements

The behaviour of cellulase enzymes in phosphate saline buffer has been studied over a wide range of temperatures and enzyme concentrations by using viscosity measurements. To characterize the conformation change of cellulase versus temperature and chemical denaturants, such as guanidinium chloride (GdmCl) and urea, the information about the intrinsic viscosity and the hydrodynamic radius are necessary. The dependence of the intrinsic viscosity and the hydrodynamic radius in its random coil conformation on temperature and denaturant concentration were studied. Our results and discussions are limited to the dilute regime of concentration because of abnormalities in conformation observed in the very dilute regime due to the presence of capillary absorption effects.     

On the modeling of fluidity loss phenomena in Couette and Poiseuille flows of elastic liquids

Some effects of the possible relaxation transition from viscoelastic liquid state to highly elastic solid state were theoretically and numerically investigated in the shear situations, within the approach proposed in papers [1, 2, 5, 16]. It was found that for a single Maxwellian model the constitutive equations developed in [1, 2, 5] are not valid at elevated shear stresses. Some new aspects of the possible rheological behavior of elastic liquids in subcritical (before transition) and supercritical (after transition) regimes were demonstrated. The mechanism of fluidity loss studied in this paper could serve as a possible trigger mechanism for the melt flow instabilities.