Adaptation of the microscopic properties of redox catalysts to the type of gas-solid reactor

Catalysts of selective oxidation usually work in a simultaneous redox mode in reactant/air cofed reactors. The solid must provide selective lattice oxygen according to a kinetic mechanism depending on operating conditions that differ from one reactor to another. Better catalytic performance can be obtained in a recirculating solids reactor because it allows separate optimization of the reduction and oxidation steps. Among the microscopic properties of the catalyst, the crystal morphology is to be taken into account because it influences its reactivity on stream. These considerations lead to a new approach of the catalyst-reaction-reactor trio.     

Structures and tribological performances of PEEK (poly-ether-ether-ketone)-based coatings designed for tribological application

Driven by economical and ecological reasons, thermoplastic-based coatings become a potential solution for anti-wear purpose. Two coating design concepts, flame spraying and printing PEEK (poly-ether-ether-ketone)-based coatings on Al substrate, were introduced in this paper. An amorphous PEEK coating was obtained by these two techniques. After being annealed, the coating presents a semi-crystalline structure. The friction and wear behaviors of PEEK-based coatings were investigated by means of ball-on-disc tests. The results show that PEEK coatings exhibit an excellent tribological performance with a relatively low coefficient of friction and wear rate. The semi-crystalline PEEK coating exhibits a lower friction coefficient and wear rate than the amorphous one. The additions of micron-sized particles such as SiC and graphite in PEEK coating can improve significantly the coating wear resistance.     

Influence of the nanostructure and morphology of (VO)2P2O7 on its catalytic reactivity

The reoxidability of vanadyl pyrophosphate is studied by thermal analysis and by temporal analysis of product (TAP). The samples differ by surface area, oxidation state of vanadium, crystallite size, and degree of crystallinity. The morphology ranges from platy to prismatic and the microstructure from mosaic crystals exhibiting {100} faces to bulky crystals. The reactivity of these samples during oxidation as well as their catalytic reactivity studied in flow reactor is accounted for by the microstructure. The highest reoxidation capability and the best catalytic properties in oxidation of n-butane to maleic anhydride are obtained with mosaic crystals. This revised version was published online in July 2006 with corrections to the Cover Date.     

Comparison of the biomechanical and biosynthetic behavior of normal human fibroblasts and fibroblasts from a forehead wrinkle

Wrinkles are the most obvious expression of skin aging and are manifested by numerous changes in the organization and structure of the dermis. To better understand if this tissue modification could be linked to a modification of cell function, contractile and synthesis capacities of normal aged human fibroblasts and those obtained from a biopsy of a forehead wrinkle were studied and compared. The capacity of fibroblasts to adhere to the collagen network and to maintain a three-dimensional structure of the dermis was studied using a three-dimensional model of a collagen gel. The metabolic activity of both cell types was determined immunochemically by quantifying collagen I synthesis. Human fibroblasts from the wrinkle contracted the collagen gel less than normal aged human fibroblasts and synthesized less collagen I. The results show that the metabolic activity of aging fibroblasts decelerates and that aging fibroblasts lose their capacity to adhere to collagen fibers, thus limiting the possibility of organizing dermal tissue.
The potential of an active ingredient to compensate for the reduction of metabolic activity and to restore the contractile capacity of fibroblasts from the wrinkle was investigated. This effect was compared with a reference molecule, vitamin C.     

Evaluation of biopsy classification for rejection: relation to detection of myocardial damage by monoclonal antimyosin antibody imaging

OBJECTIVES: This study sought to compare the histologic grades of rejection in endomyocardial biopsy specimens with the global estimate of myocardial transplant-related cardiac damage detected by myocardial uptake of monoclonal antimyosin antibodies. BACKGROUND: The diagnosis and treatment of acute cardiac allograft rejection is based on the interpretation of endomyocardial biopsies. Because allograft rejection is a multifocal process and biopsy is obtained from a small area of the right ventricle, sampling error may occur. Global assessment of myocardial damage associated with graft rejection is now possible with the use of antimyosin scintigraphy. The present study was undertaken to compare the histologic grades of rejection in endomyocardial biopsy specimens with the global assessment of transplant-related myocardial damage detected by antimyosin scintigraphy. METHODS: Biopsies (n=395) from 112 patients were independently interpreted by three pathologists in a blinded manner according to the original Stanford four-grade (normal, mild, moderate and severe) and the current International Society of Heart and Lung Transplantation (ISHLT) seven-grade (0, 1A, 1B, 2, 3A, 3B and 4) classifications. The results were correlated with 395 antimyosin studies performed at the time of the biopsies. The heart/lung ratio of antimyosin antibody uptake was used to assess the severity of myocardial damage. RESULTS: In the Stanford biopsy grade classification, significantly higher antimyosin uptake, indicating increasing degrees of myocardial damage, were associated with normal (1.78+/-0.26), mild (1.88+/-0.31) and moderate (1.95+/-0.38) biopsy classifications for rejection (p < 0.01). In the ISHLT classification, significant differences were detected only for antimyosin uptake associated with grades 0 (1.77+/-0.26) and 3A (1.98+/-0.39) but not for intermediate scores (1A, 1B and 2). In view of the similar intensity of antibody uptake among the various grades, ISHLT biopsy scores were regrouped: normal biopsies in grade A; 1A and 1B as grade B; and 2 and 3A as grade C. Antimyosin uptake in grades A, B and C was 1.78+/-0.26, 1.88+/-0.31, 1.95+/-0.38, respectively (p < 0.01). CONCLUSIONS: The current ISHLT seven-grade scoring system does not reflect the progressive severity of myocardial damage associated with heart transplant rejection. Because myocardial damage constitutes the basis of treatment for allograft rejection, there is a need to reevaluate the ISHLT grading system, given its importance for multicenter trials.     

Crystallochemistry of V---P---O phases and application to catalysis

Since the crystal structure is the result of all of the interactions between the atoms, crystal chemistry of catalysts gives information on (i) the kind of defects, (ii) what can be the atomic arrangement at the surface of the catalyst, (iii) how the active sites can be displayed. The knowledge of the reactivity of the catalyst allows one to determine what phases are really present in the steady state and to examine the influence of the precursors used in the preparation. These ideas are applied to the case of V---P---O catalysts in the oxidation of butene and butane to maleic anhydride, in which the same phase (vanadyl pyrophosphate) seems to be involved. It is shown how the methods of preparation determine the kind of redox system which is involved and how the various crystalline forms of VOPO₄ account for the different reactivities observed.     

Efficacy of augmented immunosuppressive therapy for early vasculopathy in heart transplantation

The gene encoding the inner core protein VP1 of African horse sickness virus (AHSV) serotype 9 has been cloned, expressed in vitro and entirely sequenced, completing molecular characterization of the AHSV genome. An analysis of the sequence supporting the identity of AHSV VP1 as the putative viral RNA polymerase is presented.     

A semantic matching energy function for learning with multi-relational data

Large-scale relational learning becomes crucial for handling the huge amounts of structured data generated daily in many application domains ranging from computational biology or information retrieval, to natural language processing. In this paper, we present a new neural network architecture designed to embed multi-relational graphs into a flexible continuous vector space in which the original data is kept and enhanced. The network is trained to encode the semantics of these graphs in order to assign high probabilities to plausible components. We empirically show that it reaches competitive performance in link prediction on standard datasets from the literature as well as on data from a real-world knowledge base (WordNet). In addition, we present how our method can be applied to perform word-sense disambiguation in a context of open-text semantic parsing, where the goal is to learn to assign a structured meaning representation to almost any sentence of free text, demonstrating that it can scale up to tens of thousands of nodes and thousands of types of relation.