Stereospecific analysis of phospholipid classes in rat muscle

The fatty acid and dimethyl acetal (DMA) compositions of the sn‐1 and the sn‐2 positions from individual phospholipid (PL) classes [phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidylinositol (PI)], obtained from the Longissimus dorsi muscle of rat were studied. The profile of fatty acids and DMA in the sn‐1 and sn‐2 positions of all the PL classes showed marked differences. Overall, saturated fatty acids and monounsaturated fatty acids were in a higher proportion in the sn‐1 position than in the sn‐2 one, while polyunsaturated fatty acids were mainly in the sn‐2 position. Significant differences in the DMA and fatty acid compositions between individual PL classes for each position were found. PC contained the highest proportion of palmitic acid (16:0) in the sn‐1 position and of linoleic acid (18:2 n‐6) in the sn‐2 one. The highest values for stearic acid (18:0) and DMA in the sn‐1 position and for docosahexaenoic acid (22:6 n‐3) in the sn‐2 position were found in PE. PS and PI showed the highest proportion of oleic acid (18:1 n‐9) in the sn‐1 position and of arachidonic acid (20:4 n‐6) in the sn‐2 position.     

基于运动轨迹分析的3D唇舌肌肉控制模型

针对可视化语音以及虚拟说话人系统中对唇部和舌部动画的高逼真度要求, 提出了一种基于运动轨迹分析的3D唇舌肌肉控制模型。该方法首先根据解剖学原理, 建立基于网格和纹理的唇部、舌部模型。然后, 根据分析唇部的运动轨迹, 将口轮匝肌分解成两部分来联合控制唇部的运动, 可以获得各种口型。在舌部的运动模拟中, 将它的运动轨迹分解成一些机械运动的组合, 通过使用四种肌肉模型来控制这些运动。最终实现了人脸嘴部说话时的各种口型, 实现了卷舌、舔嘴等动作。实验结果表明, 该方法能逼真地实现出唇部、舌部的运动动画。     

Surface characterization and catalytic properties of supported tungsten and platinum-tungsten carbide and oxycarbide

Bulk tungsten carbide has been prepared from ammonium paratungstate. Oxidic oxygen in relatively small amount is always present on the WC surface regardless of the method of carburization. Tungsten(VI) oxide in Al₂(WO₄)₃ can be reduced directly and in apparently one single step to the elemental W(0) state by Ar⁺ bombardment. Under H₂ the reduction starts at 720 K. In 12 and 28% W03 supported on -Al₂O₃ and in Al₂(WO₄)₃, almost 90% of the tungsten could be converted to the carbide form. Extensive hydrogenolysis products for n-hexane reactions on freshly prepared WC were observed while selectivity to isomerization associated with decrease in activity occurs upon exposure of the WC to oxygen at 620 K. Supported tungsten carbide(s) and oxycarbide(s) on -Al₂O₃ have comparable catalytic behaviour to those obtained on the bulk systems. The presence of Pt in these supported systems did not improve the catalytic performances and even did not show the catalytic properties of Pt. This was attributed to the severe conditions of catalyst preparations. Although the catalytic activity of tungsten carbide(s) obtained from the carburization of Al₂(WO₄)₃ is very low, the selectivity suggests the presence of tungsten carbide plus some WO, species.     

Three-dimensional molecular distribution in single cells analysed using the digital imaging microscope

Cellular changes in molecular distribution are believed to underly a wide range of cell functions. In order to investigate changes in molecular distribution in single cells utilizing fluorescent probes we have developed a digital imaging microscope. The system, consisting of both hardware and software, automatically acquires 3-D data sets consisting of optical sections and then processes such data to facilitate the analysis of molecular distribution in single cells. The first major step in processing reverses distortion introduced principally by the optics of the fluorescent microscope. Various procedures for accomplishing this task are compared and a method based on regularization theory is shown to give superior results for several different 3-D images. Following this step features of interest are automatically extracted from 3-D images utilizing an artificial 3-D visual system. This artificial visual system utilizes a system of spatial filters to identify regional characteristics of images, the information obtained from these filters being used to identify and characterize clusters of molecules within the image. This information is then utilized to construct a 3-D graphical model of molecular distribution in single cells. Such models are displayed in 3-D and may be further analysed utilizing interactive 3-D computer graphics. These methods are illustrated by results obtained regarding alpha-actinin distribution in single smooth muscle cells.     

Images of arterioles in unfixed tissue obtained by acoustic microscopy

A scanning acoustic microscope operating at 600 MHz was used to observe arterioles in a thin sheet of collagenous connective tissue dissected from the submucosa of the guinea-pig small intestine. The arterioles were clearly defined in images made using transmitted ultrasound, and the acoustic attenuation (α) of the arteriolar wall was estimated to be 120 cm^?1. Images made using reflected ultrasound did not show the arterioles clearly.     

A systematic approach to the discovery of new proteins of ultrastructural interest

A systematic approach to the discovery of new proteins of ultrastructural interest is discussed. It involves the merging of monoclonal antibody technology with immunocytochemical technology, particularly immunoelectron microscopy. In this approach, monoclonal antibodies are raised to a cellular preparation that can be grossly heterogeneous in its protein composition. The hybridoma culture fluids are screened by immunocytochemistry for the ultrastructural localization of their antibodies. Those monoclonal antibodies that show specific ultrastructural localizations of interest are then selected for further investigation. The antigen to which a given monoclonal antibody is directed is then identified by immunoprecipitation and immunoblotting with that antibody. By this approach, two new striated muscle proteins of ultrastructural interest have been discovered and are named zeugmatin and enactin. The former is a protein of over 500 kD localized by immunoelectron microscopy to the Z-bands, the latter of 245 kD localized to the N₁ line of striated muscle.     

Cryopreservation evaluated with mitochondrial and Z line ultrastructure in striated muscle

Single, intact, frog skeletal muscle fibres and whole frog hearts were quick-frozen on a polished, liquid-He-cooled copper block and examined in the electron microscope after freeze-substitution and freeze-fracture. In both kinds of striated muscle, collapse of the peripheral and intracristal membrane spaces in mitochondria was found to increase with increasing distance from the point of first impact (PFI) of the muscle cells on the cold copper block. The changes correlated with a previously described gradient of Z line and A band cryodamage occurring with distance from the PFI. The findings in thin sections from freeze-substituted preparations were confirmed by freeze-fracture preparations. It is concluded that, since the mitochondrial membrane changes are concurrent with, and follow the same spatial distribution of, other manifest cryoarte-facts, the cryoartefactual nature of the mitochondrial changes must be excluded before functional significance is attributed to them. The collapse of mitochondrial membrane spaces as a sensitive indicator of quality of cryopreservation may apply to non-muscle cells as well.     

Performance improvement of pneumatic artificial muscle manipulators using magneto-rheological brake

A novel pneumatic artificial muscle actuator (PAM actuator), which has achieved increased popularity to provide the advantages such as high strength and high power/weight ratio, low cost, compactness, ease of maintenance, cleanliness, readily available and cheap power source, inherent safety and mobility assistance to humans performing tasks, has been regarded during the recent decades as an interesting alternative to hydraulic and electric actuators However, some limitations still exist, such as the air compressibility and the lack of damping ability of the actuator bring the dynamic delay of the pressure response and cause the oscillatory motion Then it is not easy to realize the performance of transient response of pneumatic artificial muscle manipulator (PAM manipulator) due to the changes in the external inertia load with high speed In order to realize satisfactory control performance, a variable damper — Magneto-Rheological Brake (MRB), is equipped to the joint of the manipulator Superb mixture of conventional PID controller and a phase plane switching control method brings us a novel controller This proposed controller is appropriate for a kind of plants with nonhnearity, uncertainties and disturbances. The experiments were carried out in practical PAM manipulator and the effectiveness, of the proposed control algorithm was demonstrated through experiments, which had proved that the stability of the manipulator can be improved greatly in a high gain control by using MRB with phase plane switching control method and without regard for the changes of external inertia loads     

Unbiased estimation of human body composition by the Cavalieri method using magnetic resonance imaging

The classical methods for estimating the volume of human body compartments in vivo (e.g. skin-fold thickness for fat, radioisotope counting for different compartments, etc.) are generally indirect and rely on essentially empirical relationships — hence they are biased to unknown degrees. The advent of modern non-invasive scanning techniques, such as X-ray computed tomography (CT) and magnetic resonance imaging (MRI) is now widening the scope of volume quantification, especially in combination with stereological methods. Apart from its superior soft tissue contrast, MRI enjoys the distinct advantage of not using ionizing radiations. By a proper landmarking and control of the scanner couch, an adult male volunteer was scanned exhaustively into parallel systematic MR ‘sections’. Four compartments were defined, namely bone, muscle, organs and fat (which included the skin), and their corresponding volumes were easily and efficiently estimated by the Cavalieri method: the total section area of a compartment times the section interval estimates the volume of the compartment without bias. Formulae and nomograms are given to predict the errors and to optimize the design. To estimate an individual's muscle volume with a 5% coefficient of error, 10 sections and less than 10min point counting (to estimate the relevant section areas) are required. Bone and fat require about twice as much work. To estimate the mean muscle volume of a population with the same error contribution, from a random sample of six subjects, the workload per subject can be divided by √6, namely 4 min per subject. For a given number of sections planimetry would be as accurate but far more time consuming than point counting.     

Effect of pH on the formation of edible films made from the muscle proteins of Blue marlin (Makaira mazara)

Whole meat of Blue marlin (Makaira mazara) was used to prepare edible films. Protein solubility in film-forming solutions was high at acidic and alkaline pHs, while that at neutral pH was close to zero. Acidic and alkaline pHs improved the tensile strength while the effects of pH, on elongation at break, water vapour permeability and light transmission of the films, were not significant. From the film solubility in various protein denaturants it was revealed that the main interaction responsible for the formation of acidic and alkaline pH films was hydrophobic interaction, while that for neutral pH films was ionic bonding.