Conformational effects in the reversed-phase chromatographic behavior of recombinant human growth hormone (rhGH) and N-methionyl recombinant human growth hormone (Met-hGH).

This paper examines the retention behavior of recombinant DNA-derived human growth hormone (rhGH) in reversed-phase chromatography and its separation from the closely related N-methionyl variant (Met-hGH). It is first shown that retention for rhGH decreases with increasing column temperature when 1-propanol (1-PrOH) is used as organic modifier. On the other hand, retention increases with temperature when acetonitrile (CH3CN) is employed. The differences in behavior for the two organic modifiers could be related to conformational changes in the protein as determined by solution and adsorption intrinsic fluorescence spectroscopy. Specifically, desorption and elution of rhGH using 1-PrOH could be correlated with a solvent-induced conformational change, with retention decreasing with increasing temperature due to the increasing ease of structural alteration. On the other hand for CH3CN the increase in retention correlated with temperature rise was related to a partial structural change yielding a more hydrophobic species. In this case, a surface-driven process is suggested. The work then turned to the separation of rhGH and Met-hGH where it was found for both organic modifiers optimum separation occurred at 45 degrees C and pH 6.5. Separate studies revealed that during the conformational change Met-hGH appeared more hydrophobic than rhGH since protein-protein aggregation was observed at a lower 1-PrOH concentration. It is suggested that this hydrophobic difference, which was optimized under the conditions cited above, resulted in the separation. The study demonstrates the importance of conformational changes in retention behavior and separation of protein samples.     

Uncertainty analysis and allocation of joint tolerances in robot manipulators based on interval analysis

Many uncertain factors influence the accuracy and repeatability of robots. These factors include manufacturing and assembly tolerances and deviations in actuators and controllers. The effects of these uncertain factors must be carefully analyzed to obtain a clear insight into the manipulator performance. In order to ensure the position and orientation accuracy of a robot end effector as well as to reduce the manufacturing cost of the robot, it is necessary to quantify the influence of the uncertain factors and optimally allocate the tolerances. This involves a study of the direct and inverse kinematics of robot end effectors in the presence of uncertain factors. This paper focuses on the optimal allocation of joint tolerances with consideration of the positional and directional errors of the robot end effector and the manufacturing cost. The interval analysis is used for predicting errors in the performance of robot manipulators. The Stanford manipulator is considered for illustration. The unknown joint variables are modeled as interval parameters due to the inherent uncertainty. The cost-tolerance model is assumed to be of an exponential form during optimization. The effects of the upper bounds on the minimum cost and relative deviations of the directional and positional errors of the end effector are also studied.     

Preparation and gas-sensing characteristics of nanocrystalline spinel zinc ferrite thin films

Zinc ferrite is a promising sensor material. In this paper, thin films of nanocrystalline zinc ferrite were deposited on alumina substrates by nebulization of a 0.01-M solution of a mixture of ZnCl/sub 2/ and FeCl/sub 3/ in ethanol (Zn:Fe=1:2) followed by pyrolysis and annealing in flowing air. The resulting films were characterized by X-ray diffraction and scanning electron microscopy, and the gas-sensing properties of as-deposited films were also investigated.     

A fuzzy-based impulse noise detection and cancellation for real-time processing in video receivers

In this paper, a simple fuzzy-based algorithm to remove the impulse noise from images is proposed. To achieve real-time applications, the proposed filter architecture, which combines fuzzy noise detection and noise filtering, is also designed. With low computational complexity, simulation results show that the proposed filters effectively remove the impulse noise.     

Bi3+对纳米MnO2水热合成的影响研究

在中性和酸性条件下，以MnO2作为锰源，通过水热合成了纳米MnO2，通过XRD和TEM对产物进行的观察表明，在酸性条件下，向溶液中添加一定量的Bi^3 ，产物的晶型由α型向γ型转化，产物形貌由针状、丝状向颗粒状转变。     

Benzoquinones, a homoisoflavanone and other constitutents from Polygonatum alte-lobatum

From the rhizomes of Polygonatum alte-lobatum, two new homologous series of 1,4-benzoquinones, polygonaquinones A and B, a novel homoisoflavanone, a new gentrogenin glycoside and 13 known compounds were isolated and characterized. The structures of the new compounds were determined as two homologous series of three 2,5-dihydroxy-3-methyl-6-alkyl-1,4-benzoquinones and three 2-hydroxy-3-methyl-6-alkyl-1,4-benzoquinones, with chain lengths C21 to C23, and 4',5,7-trihydroxy-6,8-dimethylhomoisoflavanone and gentrogenin 3-O-beta-D-glucopyranosyl(1-->2)-[beta-D-xylopyranosyl(1-->3)] -beta-D-glucopyranosyl(1-->4)-beta-D-galactopyranoside.     

Renal R2 chemoreceptor activity is attenuated after back heating in the rat

The aim of the present study was to determine the afferent connections of the nucleus accumbens in snakes, in particular its catecholaminergic input. For that purpose, in vitro and in vivo applications of retrograde tracers in the nucleus accumbens of Elaphe guttata were combined with tyrosine hydroxylase (TH) immunohistochemistry. Both techniques revealed telencephalic inputs to the nucleus accumbens originating from the diagonal band of Broca, ventral pallidum, amygdaloid complex, and dorsal cortex. Major diencephalic inputs arise from the dorsomedial thalamic nucleus and the hypothalamus. In the brainstem, a few retrogradely labeled cells were observed in the raphe nucleus and the locus coeruleus. Considerably more cells were found in the midbrain tegmentum. Within the confines of the locus coeruleus and, in particular, the midbrain tegmentum, retrogradely labeled cells stained also for TH suggesting that those areas constitute the major catecholaminergic input to the nucleus accumbens of snakes. The experimental approach used in the present study, in particular the in vitro technique, seems to be very suited for studying the development of basal ganglia organization of reptiles in the near future.     

波动方程正演模型及应用

本采用声波方程，通过四阶有限差分近似，实现了复杂地质构造零炮距的数值模拟。中同时展示实际应用效果。     

A new minimum zone method for evaluating flatness errors

A new minimum zone method for flatnes error analyis is proposed in this article. Based on the criteria for the minimum zone solution and strict rules for data exchange, a simple and rapid algorithm, called the control plane rotation scheme, is developed for the flatness analysis of a flat surface. Experimental work was performed, and some examples are given in terms of the minimum zone and least-squares solutions.     

非方程灰色系统方法在长期水文预报中的应用初探

基于水文过程的复杂性和影响因子信息收集不完善这一基本事实，本文将流域水文系统视为含有灰元和灰信息的灰色系统，并初步实践了非方程灰色预报方法在长期水文预报中的应用。方法在一定意义上脱离了传统的以方程为中心的预报模式，它既考虑预报因子对预报量的不同影响程度，又不过分强调预报量与预报因子的具体相关函数形式，为长期水文预报提供了一种新思路。文中列出了实例，效果令人满意。