驱动压电PVDF换能器的高频高电压放大器

压电换能器用于NDE（非破坏性评估）应用。PVDF（聚偏氟乙烯）换能器有很多优点．包括大带宽和高灵敏度。这些换能器需要高电压和大带宽的放大器。图1中的电路源于往期的一个设计实例（参考文献1）。电路的工作原理基本相同,但本设计可以在高至500kHz频率下驱动一个2．3nF的容性负载。     

Advances in Machine Vision Applications for Automatic Inspection and Quality Evaluation of Fruits and Vegetables

Artificial vision systems are powerful tools for the automatic inspection of fruits and vegetables. Typical target applications of such systems include grading, quality estimation from external parameters or internal features, monitoring of fruit processes during storage or evaluation of experimental treatments. The capabilities of an artificial vision system go beyond the limited human capacity to evaluate long-term processes objectively or to appreciate events that take place outside the visible electromagnetic spectrum. Use of the ultraviolet or near-infrared spectra makes it possible to explore defects or features that the human eye is unable to see. Hyperspectral systems provide information about individual components or damage that can be perceived only at particular wavelengths and can be used as a tool to develop new computer vision systems adapted to particular objectives. In-line grading systems allow huge amounts of fruit or vegetables to be inspected individually and provide statistics about the batch. In general, artificial systems not only substitute human inspection but also improve on its capabilities. This work presents the latest developments in the application of this technology to the inspection of the internal and external quality of fruits and vegetables.     

Tlr2 Gene Deletion Delays Retinal Degeneration in Two Genetically Distinct Mouse Models of Retinitis Pigmentosa

Although considered a rare retinal dystrophy, retinitis pigmentosa (RP) is the primary cause of hereditary blindness. Given its diverse genetic etiology (>3000 mutations in >60 genes), there is an urgent need for novel treatments that target common features of the disease. TLR2 is a key activator of innate immune response. To examine its role in RP progression we characterized the expression profile of Tlr2 and its adaptor molecules and the consequences of Tlr2 deletion in two genetically distinct models of RP: Pde6b^rd10/rd10 (rd10) and Rho^P23H/+ (P23H/+) mice. In both models, expression levels of Tlr2 and its adaptor molecules increased in parallel with those of the proinflammatory cytokine Il1b. In rd10 mice, deletion of a single Tlr2 allele had no effect on visual function, as evaluated by electroretinography. However, in both RP models, complete elimination of Tlr2 attenuated the loss of visual function and mitigated the loss of photoreceptor cell numbers. In Tlr2 null rd10 mice, we observed decreases in the total number of microglial cells, assessed by flow cytometry, and in the number of microglia infiltrating the photoreceptor layers. Together, these results point to TLR2 as a mutation-independent therapeutic target for RP.     

ATP‐Noncompetitive Inhibitors of CDK–Cyclin Complexes

Progression through the cell division cycle is controlled by a family of cyclin‐dependent kinases (CDKs), the activity of which depends on their binding to regulatory partners (cyclins A–H). Deregulation of the activity of CDKs has been associated with the development of infectious, neurodegenerative, and proliferative diseases such as Alzheimer's, Parkinson's, or cancer. Most cancer cells contain mutations in the pathways that control the activity of CDKs. This observation led this kinase family to become a central target for the development of new drugs for cancer therapy. A range of structurally diverse molecules has been shown to inhibit the activity of CDKs through their activity as ATP antagonists. Nevertheless, the ATP binding sites on CDKs are highly conserved, limiting the kinase specificity of these inhibitors. Various genetic and crystallographic approaches have provided essential information about the mechanism of formation and activation of CDK–cyclin complexes, providing new ways to implement novel research strategies toward the discovery of new, more effective and selective drugs. Herein we review the progress made in the development of ATP‐noncompetitive CDK–cyclin inhibitors.     

Peptides and Peptide Mimics as Modulators of Apoptotic Pathways

Cells in the balance : Programmed cell death is an important and stringently controlled process. Aberrancies in its control mechanisms can lead to disease; overactive apoptosis can cause neurodegenerative disorders, whereas deficient apoptotic activity can lead to cancer. Therefore, controlling apoptotic pathways with peptides is showing increasing promise as a strategy in drug development.

     

Possible proton conduction in Ce<Subscript>0.9</Subscript>Gd<Subscript>0.1</Subscript>O<Subscript>2−δ</Subscript> nanoceramics

Dense samples of Ce_0.9Gd_0.1O_2−δ with grain sizes in the range 91–252 nm were prepared and their electrical properties studied by impedance spectroscopy. It was found that the bulk conductivity is not affected by grain size or atmosphere and that small grain sizes lead to a larger total resistance of the material. The most striking result corresponds to a sample sintered in wet air that exhibited electrical characteristics that hint clearly at the presence of proton conduction at temperatures below 200 °C.     

A unified statistical framework for monitoring multivariate systems with unknown source and error signals

This article proposes a unified multivariate statistical monitoring framework that incorporates recent work on maximum likelihood PCA (MLPCA) into conventional PCA-based monitoring. The proposed approach allows the simultaneous and consistent estimation of the PCA model plane, its dimension and the error covariance matrix. This paper also invokes recent work on monitoring non-Gaussian processes to extract unknown Gaussian as well as non-Gaussian source signals from recorded process data. By contrasting the unified framework with PCA-based process monitoring using a simulation example and recorded data from two industrial processes, the proposed approach produced more accurate and/or sensitive monitoring models.     

Dried sludges and sludge-based chars for H2S removal at low temperature: influence of sewage sludge characteristics

The use of sewage sludge as a precursor of adsorbent/ catalyst materials for environmental applications has been encouraged during the past few years. Due to the heterogeneous nature of sludges, there exists a lack of information regarding the characteristics of these low-cost precursors and how their physicochemical properties affect the final performance of materials prepared from them. In this work, three sewage-sludges collected at WWTPs with assorted sludge/wastewater treatment schemes were used as precursors of adsorbents/catalysts for H2S removal at room temperature. All the solidswere characterized to establish their textural properties and chemical composition, including the speciation of the adsorbents/ catalysts inorganic fraction. Thermal treatment (gasification) of the raw (dried) sludges increased the H2S removal ability in all cases. For these thermally treated materials, catalytic conversion to elemental sulfur and sulfate moieties was found to be the main route of H2S removal. Results indicate that adsorbents based on an iron/calcium-containing sludge were the most reactive and exhibited the highest capacities for H2S retention. Forthis particulartype of sludge, a reasonably good performance was observed even when the dried (raw) sludge was used as adsorbent/ catalyst. Alternatively, the oxidation of H2S by chars obtained from the other two sludges under study was related to their textural properties.     

Chemical enhancers for the absorption of substances through the skin: Laurocapram and its derivatives

Absorption enhancers are substances used for temporarily increasing a membrane's permeability (e.g., the skin and mucosa), either by interacting with its components (lipids or proteins) or by increasing the membrane/vehicle partition coefficient. This article presents the results of biophysical and permeability studies performed with Laurocapram and its analogues. As shown, Laurocapram and its analogues present different enhancing efficacies, for most of both hydrophilic and lipophilic substances. The enhancing effect of Laurocapram (Azone) is attributed to different mechanisms, such as insertion of its dodecyl group into the intercellular lipidic bilayer, increase of the motion of the alkylic chains of lipids, and fluidization of the hydrophobic regions of the lamellate structure. Toxicological studies reveal a low toxicity for Laurocapram, and for some derivatives, a relationship exists between toxicity and the number of carbons in the alkylic chain. Very important, when applied to human skin, Laurocapram shows a minimal absorption, being quickly eliminated from circulation. However, although Laurocapram and its derivatives have been shown to provide enhancement, they have not been widely accepted because of their suspected pharmacological activity or questions about their safety.     

Exploiting the capabilities of modern GPUs for dense matrix computations

We present several algorithms to compute the solution of a linear system of equations on a graphics processor (GPU), as well as general techniques to improve their performance, such as padding and hybrid GPU‐CPU computation. We compare single and double precision performance of a modern GPU with unified architecture, and show how iterative refinement with mixed precision can be used to regain full accuracy in the solution of linear systems, exploiting the potential of the processor for single precision arithmetic. Experimental results on a GTX280 using CUBLAS 2.0, the implementation of BLAS for NVIDIA^® GPUs with unified architecture, illustrate the performance of the different algorithms and techniques proposed. Copyright © 2009 John Wiley & Sons, Ltd.