Infiltration behavior of Cu and Ti fillers into Ti2AlC/Ti3AlC2 composites during tungsten inert gas (TIG)brazing

Herein we study the infiltration behavior of Ti and Cu fillers into a Ti₂AlC/Ti₃AlC₂MAX phase composites using a TIG-brazing process. The microstructures of the interfaces were investigated by scanning electron microscopy and energy dispersive spectrometry. When Ti₂AlC/Ti₃AlC₂ comes into contact with molten Ti, it starts decomposing into TiC_x, a Ti-richandTi₃AlC; when in contact with molten Cu, the resulting phases are Ti₂Al(Cu)C, Cu(Al), AlCu₂Ti and TiC. In the presence of Cu at approximately 1630 °C, a defective Ti₂Al(Cu)C phase was formed having a P63/mmc structure. Ti₃AlC₂ MAX phase was completely decomposed in presence of Cu or Ti filler-materials. The decomposition of Ti₂AlC to Ti₃AlC₂ was observed in the heat-affected zone of the composite. Notably, no cracks were observed during TIG-brazing of Ti₂AlC/Ti₃AlC₂ composite with Ti or Cu filler materials.     

Reacteur a cellules nitrifiantes immobilisees sur garnissage aere a co- ou contre-courant. Etude experimentale et modelisationNitrification by attached-cell reactors aerated at co- or counter-current. Experimental data and modelling

Attached-cell reactors using a bed of granular material for wastewater treatment develop a high biomass concentration which allows an important reduction of the required residence time (Jeris et al., 1977; Elmaleh, 1982). In nitrification of ammonia containing wastewater, oxygen is currently the limiting substrate; in theory, 4.18 g of oxygen are required per 1 g of nitrogen (Painter, 1970). Oxygen can be added with hydrogen peroxide (Grigoropolou, 1980; Seropian, 1980; Yahi et al., 1982) which is nevertheless expensive and it seems better to transfer oxygen from a gas phase, i.e. air, to the liquid phase through a fixed bed (Charpentier, 1976).Two attached-cell reactors (Fig. 1) were operated in parallel for nitrification of ammonia containing synthetic wastewater (Table 2). Air was upflowed through a granular packing (Table 1) maintained in fixed bed while the liquid influent was injected at co- or counter-current.

1. (1) Owing to the high oxygen transfer properties of the system and to the fact that the thickness of biofilm is always less than 100 μm, the whole process was not limited by oxygen concentration of which remained larger than 7 mg l⁻¹ (Fig. 2a) (Bungay et al., 1969). Oxidised nitrogen ammonia is completely converted into nitrate (Fig. 2b). Experimental conditions are given in Table 3.

2. (2) The plot of ammonia conversion against air superficial velocity shows a maximum (Fig. 3) after which conversion decreases rapidly by overloading of the packing (Prost, 1965). Experimental conditions are given in Table 4.

3. (3) Process efficiency decreases when superficial upflow velocity is increased (Fig. 4).

4. (4) Complete abatement of inlet pollution is reached when nitrogen concentration is less than 25 mg l⁻¹ (Fig. 5) which corresponds to a volumetric loading up to 0.6 kg N (NH₄⁺) m⁻³ day⁻¹.

Moreover, the experimental data were fitted to a model based on classical assumptions (Roques, 1980; Grady, 1982; Atkinson and Fowler, 1974; Grasmick et al., 1979; Grasmick, 1982; Harremoes, 1976, 1978; Jennings et al., 1976; Williamson and MacCarty, 1976); i.e. zero order intrinsic kinetics and diffusion transport (Table 5), and recently developed (Grasmick, 1982; Rodrigues et al., 1984). This model provides, particularly, a very easy method to check its own use—in reaction regime and in diffusion regime—when time spans or inlet concentration are changed; experimental results can indeed be plotted in such a way that straight lines are obtained (Table 6). Figures 6 and 7 show the data obtained with the counter-current nitrification reactor when respectively inlet concentration and time spans are varied. The plotted straight lines show that the overall reaction is zero order and that, therefore, the biofilm is fully penetrated. A critical time span θ_c and a critical inlet concentration C_c, for which complete conversion is achieved, are then calculated, θ_c is theoretically proportional to C₁ which is verified in Fig. 8. The straight line θ_c vs C₁ can then be used in reactor design.     

SPC3, a V3 loop-derived synthetic peptide inhibitor of HIV-1 infection, binds to cell surface glycosphingolipids

Synthetic multibranched peptides derived from the V3 domain of human immunodeficiency virus type 1 (HIV-1) gp120 inhibit HIV-1 entry into CD4+ and CD4- cells by two distinct mechanisms: competitive inhibition of HIV-1 binding to CD4-/GalCer+ colon cells and postbinding inhibition of HIV-1 fusion with CD4+ lymphocytes. In the present study, we have characterized the cellular binding sites for the V3 peptide SPC3, which possesses eight V3 consensus motifs GPGRAF radially branched on a neutral polyLys core matrix. These binding sites are glycosphingolipids that share a common structural determinant, i.e., a terminal galactose residue with a free hydroxyl group in position 4: GalCer/sulfatide on CD4-/GalCer+ colon cells; LacCer and its sialosyl derivatives GM3 and GD3 on CD4+ human lymphocytes. These data suggest that the V3 peptide binds to the GalCer/sulfatide receptor for HIV-1 gp120 on HT-29 cells and thus acts as a competitive inhibitor of virus binding to these CD4- cells, in full agreement with previously published virological data. In contrast, SPC3 does not bind to the CD4 receptor, in agreement with the data showing that the peptide inhibits HIV-1 infection of CD4+ cells by acting at a postattachment step. The binding of SPC3 to LacCer, GM3, and GD3, expressed by CD4+ lymphocytes, suggests a role for these glycosphingolipids in the fusion process between the viral envelope and the plasma membrane of CD4+ cells. Since the multivalent peptide can theoretically bind to several of these glycosphingolipids, we hypothesize that the resulting cross-linking of membrane components may affect the fluidity of the plasma membrane and/or membrane curvature, altering the virus-cell fusion mechanism.     

A New Default Theories Compilation for MSP-Entailment

Handling exceptions represents one of the most important problems in Artificial Intelligence. Several approaches have been proposed for reasoning on default theories. This paper focuses on a possibilistic approach, and more precisely on the MSP-entailment (where MSP stands for Minimum Specificity Principle) from default theories which is equivalent to System P augmented by rational monotony. In order to make this entailment tractable from a computational point of view, we propose here a compilation of default theories with respect to a target compilation language. This allows us to provide polynomial algorithms to derive efficiently the MSP-conclusions of a compiled default theory. Moreover, the proposed compilation is qualified to be flexible since it efficiently takes advantage of any classical compiler and generally provides a low recompilation cost when updating a compiled default theory.     

An effective operations permutation-based discrete harmony search approach for the flexible job shop scheduling problem with makespan criterion

The Flexible Job Shop Scheduling Problem (FJSSP) represents a challenging applicative problem for metaheuristic algorithms because it imposes the development of innovative domain-dependent search operators that have to deal both with its combined discrete and permutation nature. Emerging as an effective approach for the resolution of a broad spectrum of hard optimization problems, some few discrete declinations of the Harmony Search (HS) algorithm have been recently proposed for tackling the FJSSP. Recent advances include an investigation of an innovative and promising permutation-based proposal. Accordingly, this paper proposes an Effective Operations Permutation-based Discrete Harmony Search (EOP-DHS) approach for FJSSP with Makespan criterion. The approach adopts an integrated two-part “affectation-sequencing” representation of the solution harmony and a dedicated improvisation operator particularly adapted to the integer-valued and operations permutation-based used coding scheme. Besides, a Modified Intelligent Mutation (MIM) operator is integrated to the adopted framework in order to enhance its overall search ability. Mainly, by balancing maximum machine workload during the overall search process, MIM operator allows essentially maintaining and enhancing the reciprocal equilibrium of diversification and intensification abilities of the proposed EOP-DHS algorithm. Conducted numerical experimentations on 188 benchmarking instances validate the proposal comparatively to a representative set of previously deployed metaheuristic approaches to FJSSP with Makespan criterion. Furthermore, main contribution of the paper is extended with an experimental procedure proving the effectiveness of the adopted permutation-based HS scheme for the resolution of combinatorial optimization problems. Hard benchmarking instances of the classical Job Shop Scheduling Problem (JSSP) are thus considered for exemplification.     

Multibranched V3 peptides inhibit human immunodeficiency virus infection in human lymphocytes and macrophages

Synthetic polymeric constructions (SPCs) including the consensus sequence of the human immunodeficiency virus type 1 (HIV-1) surface envelope glycoprotein gp120 V3 loop (GPGRAF) blocked the fusion between HIV-1- and HIV-2-infected cells and CD4+ uninfected cells. A structure-activity relationship study using V3 SPC analogs showed that the most efficient inhibitor of cell fusion was an eight-branched SPC with the hexapeptide motif GPGRAF (i.e., [GPGRAF]8-SPC). N-terminal acetylation or incorporation of D-amino acids in the GPGRAF sequence of this SPC resulted in significant loss of activity. Analogs with fewer than six residues in the motif (i.e., GPGRA or GPGR), as well as SPCs with a nonrelevant sequence, did not inhibit cell fusion, demonstrating the high specificity of the antifusion activity. [GPGRAF]8-SPC, which was not toxic to CEM cells at concentrations of up to 50 microM, inhibited 50% of HIV-1(LAI) replication in these cells at a concentration of 0.07 microM. Moreover, [GPGRAF]8-SPC inhibited the infection of human peripheral blood mononuclear cells by several HIV-1 and HIV-2 isolates, including laboratory strains [HIV-1(LAI), HIV-1(NDK), and HIV-2(ROD)], and fresh primary isolates, including two zidovudine-resistant HIV-1 isolates and two HIV-2 isolates obtained from infected individuals. The multibranched peptide also inhibited infection of human primary macrophages by the highly cytopathic macrophage-tropic isolate HIV-1(89.6). The antiviral activity of [GPGRAF]8-SPC was not related to a virucidal effect, since preincubation of HIV-1 with the peptide did not affect its infectious titer. This result is in agreement with the concept that the multibranched peptide mimics a part of the V3 loop and thus interacts with the host cell. The therapeutic properties of synthetic multibranched peptides based on the V3 loop consensus motif should be evaluated in HIV-infected patients.     

AmyP53, a Therapeutic Peptide Candidate for the Treatment of Alzheimer’s and Parkinson’s Disease: Safety,Stability, Pharmacokinetics Parameters and Nose-to Brain Delivery

Neurodegenerative disorders are a major public health issue. Despite decades of research efforts, we are still seeking an efficient cure for these pathologies. The initial paradigm of large aggregates of amyloid proteins (amyloid plaques, Lewis bodies) as the root cause of Alzheimer’s and Parkinson’s diseases has been mostly dismissed. Instead, membrane-bound oligomers forming Ca²⁺-permeable amyloid pores are now considered appropriate targets for these diseases. Over the last 20 years, our group deciphered the molecular mechanisms of amyloid pore formation, which appeared to involve a common pathway for all amyloid proteins, including Aβ (Alzheimer) and α-synuclein (Parkinson). We then designed a short peptide (AmyP53), which prevents amyloid pore formation by targeting gangliosides, the plasma membrane receptors of amyloid proteins. Herein, we show that aqueous solutions of AmyP53 are remarkably stable upon storage at temperatures up to 45 °C for several months. AmyP53 appeared to be more stable in whole blood than in plasma. Pharmacokinetics studies in rats demonstrated that the peptide can rapidly and safely reach the brain after intranasal administration. The data suggest both the direct transport of AmyP53 via the olfactory bulb (and/or the trigeminal nerve) and an indirect transport via the circulation and the blood–brain barrier. In vitro experiments confirmed that AmyP53 is as active as cargo peptides in crossing the blood–brain barrier, consistent with its amino acid sequence specificities and physicochemical properties. Overall, these data open a route for the use of a nasal spray formulation of AmyP53 for the prevention and/or treatment of Alzheimer’s and Parkinson’s diseases in future clinical trials in humans.     

Road intersection detection and classification using hierarchical SVM classifier

In this paper, a hierarchical multi-classification approach using support vector machines (SVM) has been proposed for road intersection detection and classification. Our method has two main steps. The first involves the road detection. For this purpose, an edge-based approach has been developed using the bird’s eye view image which is mapped from the perspective view of the road scene. Then, the concept of vertical spoke has been introduced for road boundary form extraction. The second step deals with the problem of road intersection detection and classification. It consists on building a hierarchical SVM classifier of the extracted road forms using the unbalanced decision tree architecture. Many measures are incorporated for good evaluation of the proposed solution. The obtained results are compared to those of Choi et al. (2007).