Synthesis of 2-hydroxy acid from 2-amino acid by Clostridium butyricum

Cultures of Clostridium butyricum type strain in synthetic medium supplemented with various L-2-amino acids revealed the presence of the corresponding 2-hydroxy acid. This metabolite is able to produce the polyester poly(2-hydroxyalkanoic acid). The bioconversion is not stereoselective since D-2-amino acids were also converted. Chiral GC analysis demonstrated that only D-enantiomer is formed from L-leucine.     

Understanding the atomic force microscopy image of the V2O5 and Li0.03V2O5(0 0 1) surface using ab initio calculations

Single crystals of V₂O₅ and Li_0.03V₂O₅ were imaged in ambient conditions by atomic force microscopy (AFM). Atomic-scale resolution images are compared with total electron-density plots of the surface calculated using the ab initio HartreeFock method. The calculated oxygen charge at the V₂O₅(0 1 0) surface suggests an increased local reactivity of the bridging oxygens with respect to electrophilic attacks by adsorbate molecules. The intercalation of lithium has no consequence on the reactivity of the surface. This is supported by results from electrostatic potentials calculated from the cluster charge distributions.     

Plasminogen activator inhibitor-1 regulation in cultured rat peritubular cells by basic fibroblast growth factor and transforming growth factor-alpha

In the present study we examined the in vitro regulation of plasminogen activator inhibitor I (PAI-1) expression in peritubular cells recovered from 20-day-old rat testes. We tested two growth factors, basic fibroblast growth factor (bFGF) and transforming growth factor-alpha (TGF alpha). They are synthesized by Sertoli cells, and peritubular cells exhibit the corresponding high affinity receptors. After exposure to bFGF or TGF alpha (0.1-30 ng/ml), PAI-1 messenger RNA levels, as determined by Northern hybridization analysis, increased in a dose-dependent manner. The first significant effects were noted after 2-h exposure to bFGF or TGF alpha (10 ng/ml), and PAI-1 messenger RNA levels were maximally stimulated approximately 12-fold (bFGF) and 8-fold (TGF alpha) after 4 h. The two growth factors increased the amount of immunoreactive (Western blots) and biologically active (Stachrom) PAI-1 measured in the culture medium. Actinomycin D inhibited the effects of these factors, whereas cycloheximide augmented them. Phorbol myristate acetate, an activator of protein kinase C, mimicked the effects of bFGF and TGF alpha. Interestingly, long term (24-h) pretreatment with phorbol myristate acetate resulted in a severe loss of responsiveness to bFGF or TGF alpha. Staurosporine, an inhibitor of protein kinase C, also significantly reduced the effects of bFGF and TGF alpha. Given that PAI-1 inhibits Sertoli cell plasminogen activator activity and that bFGF and TGF alpha are synthesized by Sertoli cells, these factors are likely to interact to regulate protease activity in localized regions of the seminiferous tubule.     

Pressure dependence of positron annihilation in InP

We have obtained the valence electron and positron charge densities in InP from wavefunctions derived in a model pseudopotential bandstructure calculation at normal and under hydrostatic pressure. We find that the positron density is maximum in the open interstices and is excluded not only, as usual, from the ion cores but also to a considerable degree from the valence bonds. Electron-positron momentum densities are calculated for the (001–110) plane. The results are used to analyze the positron effect in InP.     

A Cryptographic-Based Approach for Electricity Theft Detection in Smart Grid

In order to strengthen their security issues, electrical companies devote particular efforts to developing and enhancing their fraud detection techniques that cope with the information and communication technologies integration in smart grid fields. Having been treated earlier by several researchers, various detection schemes adapted from attack models that benefit from the smart grid topologies weaknesses, aiming primarily to the identification of suspicious incoming hazards. Wireless meshes have been extensively used in smart grid communication architectures due to their facility, lightness of conception and low cost installation; however, the communicated packets are still exposed to be intercepted maliciously in order either to falsify pertinent information like the smart meter readings, or to inject false data instead, aiming at electricity theft during the communication phase. For this reason, this paper initiates a novel method based on RSA cryptographic algorithm to detect electricity fraud in smart grid. This new method consists of generating two different cryptograms of one electricity measurement before sending, after which the recipient is used to find the same value after decrypting the two cyphers in a normal case. Otherwise, a fraudulent manipulation could occur during the transmission stage. The presented method allows us to kill two birds with one stone. First, satisfactory outcomes are shown: the algorithm accuracy reaches 100%, from one hand, and the privacy is protected thanks to the cryptology concept on the other hand.     

Analysis of time varying errors in quadratic finite element approximation of hyperbolic problems

A methodology for analysing the numerical errors generated by schemes using high-order approximation is presented. Based on Fourier analysis, this methodology is illustrated through the study of the θ-weighting Taylor–Galerkin finite element model applied to an unsteady one-dimension advection problem with quadratic elements. Results show that the dissipation and dispersion errors may be computed by considering simultaneously the so-called physical and computational modes and then, contrarily to what is shown when linear approximation is considered, these errors present a transient behaviour. Moreover, it appears that the errors computed at the end node and at the middle node present in general a different behaviour which in some cases may be opposed to one another. Numerical tests are presented to support the validity of the proposed strategy. We recommend strongly the use of this method for studying the behaviour of numerical schemes based on high-order approximations.     

Pansharpening multispectral remote sensing data by multiplicative joint nonnegative matrix factorization

Pansharpening aims at combining observable panchromatic and multispectral images to generate an unobservable image with the high spatial resolution of the former and the spectral diversity of the latter. In this paper a new fusion method is proposed. This method, related to linear spectral unmixing (LSU) techniques and based on non-negative matrix factorization (NMF), optimizes, by new iterative–multiplicative update rules, a joint criterion that exploits a spatial degradation model between the two images. The proposed Multiplicative Joint Non-negative Matrix Factorization (MJNMF) approach is applied to synthetic and real data, and its effectiveness in spatial and spectral domains is evaluated with commonly used performance criteria. Experimental results show that the proposed method yields good spectral and spatial fidelities of the pansharpened data. Also, it outperforms those tested from the literature.     

Energetic considerations for the photoisomerization of vinyl cinnamates

The particular structural changes and photosensitivity of the poly (vinyl cinnamate) (PVCN) have been the subject of intense experimental and theoretical investigations. In the present work quantum calculations are carried out in order to determine the energy required for configurational changes. The calculated reaction path between different structures and the localization of the transition state exhibit a high photosensitivity in the visible or the near infrared spectrum for this ester and related compounds such as the fluorinated molecules in different positions of the aromatic group.     

Study of hydrogen production system by using PV solar energy and PEM electrolyser in Algeria

Hydrogen fuel can be produced by using solar electric energy from photovoltaic (PV) modules for the electrolysis of water without emitting carbon dioxide or requiring fossil fuels.