A Multicell Linear Power Amplifier for Driving Piezoelectric Loads

A multicell amplifier is developed by connecting floating signal modules in series to drive piezoelectric devices. The amplifier generates a high voltage gain by summing the individual module gains. The bandwidth equals that of a single module. The multicell amplifier provides a means of achieving high power and can divide the total power dissipation among the modules, because each module delivers the same output voltage and current. A prototype circuit that consists of six floating signal modules exhibits precise linear operation over a wide range of input frequencies and capacitive loads. The circuit provides a plusmn 200-V output swing with a corner frequency of around 100 kHz at a driving capacitive load of 0.1 muF. The slew rate is as high as 115 V/mus, and the maximum output current is plusmn2.6 A. The practicality and performance of the presented modular implementation concepts were verified by the close match between the simulated and experimental results.     

Salvianolic acid B inhibits low‐density lipoprotein oxidation and neointimal hyperplasia in endothelium‐denuded hypercholesterolaemic rabbits

BACKGROUND: Atherosclerosis and restenosis are inflammatory responses involving free radicals and lipid peroxidation and may be prevented/cured by antioxidant‐mediated lipid peroxidation inhibition. Salvianolic acid (Sal B), a water‐soluble antioxidant obtained from a Chinese medicinal herb, is believed to have multiple preventive and therapeutic effects against human vascular diseases. In this study the in vitro and in vivo inhibitory effects of Sal B on oxidative stress were determined. RESULTS: In human aortic endothelial cells (HAECs), Sal B reduced oxidative stress, inhibited low‐density lipoprotein (LDL) oxidation and reduced oxidised LDL‐induced cytotoxicity. Sal B inhibited Cu²⁺‐induced LDL oxidation in vitro (with a potency 16.3 times that of probucol) and attenuated HAEC‐mediated LDL oxidation as well as reactive oxygen species (ROS) production. In cholesterol‐fed New Zealand White rabbits (with probucol as positive control), Sal B intake reduced Cu²⁺‐induced LDL oxidation, lipid deposition in the thoracic aorta, intimal thickness of the aortic arch and thoracic aorta and neointimal formation in the abdominal aorta. CONCLUSION: The data obtained in this study suggest that Sal B protects HAECs from oxidative injury‐mediated cell death via inhibition of ROS production. The antioxidant activity of Sal B may help explain its efficacy in the treatment of vascular diseases. Copyright © 2010 Society of Chemical Industry     

Rare Gain-of-Function KCND3 Variant Associated with Cerebellar Ataxia,Parkinsonism, Cognitive Dysfunction,and Brain Iron Accumulation

Loss-of-function mutations in the K_V4.3 channel-encoding KCND3 gene are linked to neurodegenerative cerebellar ataxia. Patients suffering from neurodegeneration associated with iron deposition may also present with cerebellar ataxia. The mechanism underlying brain iron accumulation remains unclear. Here, we aim to ascertain the potential pathogenic role of KCND3 variant in iron accumulation-related cerebellar ataxia. We presented a patient with slowly progressive cerebellar ataxia, parkinsonism, cognitive impairment, and iron accumulation in the basal ganglia and the cerebellum. Whole exome sequencing analyses identified in the patient a heterozygous KCND3 c.1256G>A (p.R419H) variant predicted to be disease-causing by multiple bioinformatic analyses. In vitro biochemical and immunofluorescence examinations revealed that, compared to the human K_V4.3 wild-type channel, the p.R419H variant exhibited normal protein abundance and subcellular localization pattern. Electrophysiological investigation, however, demonstrated that the K_V4.3 p.R419H variant was associated with a dominant increase in potassium current amplitudes, as well as notable changes in voltage-dependent gating properties leading to enhanced potassium window current. These observations indicate that, in direct contrast with the loss-of-function KCND3 mutations previously reported in cerebellar ataxia patients, we identified a rare gain-of-function KCND3 variant that may expand the clinical and molecular spectra of neurodegenerative cerebellar disorders associated with brain iron accumulation.     

Mechanical alloyed Ti–Cu–Ni–Si–B amorphous alloys with significant supercooled liquid region

This study examined the glass formation range of Ti_94–x–yCu_xNi_ySi₄B₂ alloy powders synthesized by mechanical alloying technique. According to the results, after 5–7 h of milling, the mechanically alloyed powders were amorphous at compositions with (x+y) equal to 20–40%. For the compositions with (x+y) larger than 45% or smaller than 10%, the structure of ball-milled powders is a partial amorphous single phase or coexistent partial amorphous and crystalline phases, respectively. The thermal stability of the amorphous powders was also investigated by differential thermal analysis. As the results demonstrated, several amorphous powders were found to exhibit a wide supercooled liquid region before crystallization. The temperature interval of the supercooled liquid region defined by the difference between T_g and T_x, i.e. ΔT(=T_x–T_g), are 52 K for Ti₇₄Ni₂₀Si₄B₂, 74 K for Ti₆₄Ni₃₀Si₄B₂, 58 K for Ti₆₄Cu₂₀Ni₁₀Si₄B₂, and 61 K for Ti₇₄Cu₁₀Ni₁₀Si₄B₂.     

Preparation and characterization of polystyrene–clay nanocomposites by free‐radical polymerization

The polymerizable cationic surfactant, vinylbenzyldimethylethanolammouium chloride (VBDEAC), was synthesized to functionalize montmorillonite (MMT) clay and used to prepare exfoliated polystyrene–clay nanocomposites. The organophilic MMT was prepared by Na⁺ exchanged montmorillonite and ammonium cations of the VBDEAC in an aqueous medium. Polystyrene–clay nanocomposites were prepared by free‐radical polymerization of the styrene containing intercalated organophilic MMT. Dispersion of the intercalated montmorillonite in the polystyrene matrix determined by X‐ray diffraction reveals that the basal spacing is higher than 17.6 nm. These nanocomposites were characterized by differential scanning calorimetry (DSC), transmission electron micrograph (TEM), thermal gravimetric analysis (TGA), and mechanical properties. The exfoliated nanocomposites have higher thermal stability and better mechanical properties than the pure polystyrene. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1370–1377, 2002     

Water bamboo husk‐reinforced poly(butylene succinate) biodegradable composites

The water bamboo husk is one of major agricultural wastes in Taiwan. In this study, the fiber and powder obtained from the water bamboo husk were chemically modified by coupling agents. Furthermore, the modified fiber and powder were added to the biodegradable polymer poly(butylene succinate) (PBS) separately, to form novel fiber‐reinforced composites. Morphologies, mechanical properties, and heat resistance of these water bamboo husk‐reinforced composites were investigated. The results indicate that the fibers modified by coupling agents exhibited better compatibility with the polymer matrixes than did the untreated fibers. Moreover, it is found that the thermal properties were improved as plant fiber was incorporated to those polymers. Furthermore, the mechanical properties were also increased with the addition of coupling agent‐treated fiber. On the other hand, it is found that the homogeneity of untreated powder‐containing samples is better than that of untreated fiber‐containing samples. Moreover, the results reveal that the powders modified with coupling agents were not effective in improving the mechanical properties of the reinforced PBS. This is due to the bulky structure of lignin leading to a smaller reaction ratio with the coupling agents. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 188–199, 2006     

Environmentally conscious design by using fuzzy multi-attribute decision-making

Products affect the environment at many points in their life cycles. Once a product moves from the drawing board into the production line, its environmental attributes are largely fixed. Many researchers focus on developing intelligent systems to provide a variety of design and manufacturing information to help designers make environmentally conscious decisions. However, in the early design stage, not all the information available is precise. A large amount of information, especially that which is based on designer experience, is fuzzy in nature. This paper presents an innovative method, namely, green fuzzy design analysis (GFDA), which involves simple and efficient procedures, to evaluate product design alternatives based on environmental consideration using fuzzy logic. The hierarchical structure of environmentally conscious design indices was constructed using the analytical hierarchy process (AHP), which includes five aspects: (1) energy, (2) recycling, (3) toxicity, (4) cost, and (5) material. After weighting factors for the environmental attributes are determined, the most desirable design alternative can be selected based on the fuzzy multi-attribute decision-making (FMADM) technique. The benefit of using such a technique is to effectively solve the design problem by capturing human expertise .     

ADAPTIVE CONTROL AND SYNCHRONIZATION OF CHUA'S CIRCUITS

In this work, we address the adaptive control and synchronization problems of Chua's circuits with unknown system parameters. Adaptive controllers with single state feedback are derived such that the trajectory of the Chua's circuit is globally stabilized to an equilibrium point of the uncontrolled system. In addition, the proposed adaptive control schemes are then applied to achieve state synchronization of two identical Chua's circuits. Furthermore, based on the Lyapunov approach, the closed-loop systems are proved to be globally exponentially or asymptotically stable. Numerical results and Pspice simulations demonstrate the proposed control scheme's effectiveness.     

On decoding of both errors and erasures of a Reed-Solomon codeusing an inverse-free Berlekamp-Massey algorithm

In a previous article by Truong et al. (see ibid., vol.46, p.973-76, 1998), it was shown that an inverse-free Berlekamp-Massey (1968, 1969) algorithm can be generalized to find the error locator polynomial in a Reed-Solomon (RS) decoder for correcting errors as well as erasures. The basic idea of this procedure is the replacement of the initial condition of an inverse-free BM algorithm by the Forney (1965) syndromes. It is shown that the errata locator polynomial can be obtained directly by initializing an inverse-free BM algorithm with the erasure locator polynomial and the syndromes. An important ingredient of this new algorithm is a modified BM algorithm for computing the errata locator polynomial. As a consequence, the separate computation of the erasure locator polynomial and the Forney syndrome, needed in the decoder developed by Truong et al., are completely avoided in this modification of the BM algorithm. This modified algorithm requires fewer finite field addition and multiplication operations than the previous algorithm. Finally, the new decoding method was implemented on a computer using C++ language. It is shown in a simulation that the speed of this new decoder is faster than the decoder developed by Truong et al. An example using this program is given for an (255, 239) RS code for correcting errors and erasures with 2ν+s⩽10     

Studies of electrochemical colored coating

The aqueous emulsion bath of cationic electrodeposition-colored coating was studied by cyclic voltammetry. The effects of pH and the distance between the cathode and anode on deposition potential and deposition current density were also observed. The deposition of colored coating was recorded by chronoamperometry, and the deposit was studied by UV/VIS absorption spectroscopy. The ratio of resin to pigment in the deposit was estimated from chronoamperometry. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2719–2727, 1998