Efficient Enantioselective Syntheses of Sertraline, 2‐Epicatalponol and Catalponol from Tetralin‐1,4‐dione

Tetralin‐1,4‐dione, the stable tautomer of dihydroxynaphthalene, was reduced with catecholborane in the presence of 3,3‐diphenyl‐1‐butyltetrahydro‐3H‐pyrrolo[1,2‐c][1,3,2]oxazaborole as catalyst to give enantiomerically highly enriched 4‐hydroxy‐1‐tetralone (99% ee) in an efficient one‐pot procedure. The R‐enantiomer provided a rapid access to sertraline while the S‐enantiomer was converted into 2‐epicatalponol and catalponol. A more selective enantioselective route to the antithermitic catalponol made use of the planar chiral tricarbonylchromium complex of hydroxytetralone. Its precursor chromium(tricarbonyl)[η⁶‐(1‐4,4a,8a)‐tetralin‐5,8‐dione] was obtained via direct complexation of 1,4‐dihydroxynaphthalene using chromium(tricarbonyl)‐ tris(ammonia) and boron trifluoride etherate as source of the chromium(tricarbonyl) fragment. Enolate prenylation was best carried out in the presence of a tetraamine ligand. Complete inversion of the stereogenic center bearing the prenyl group of the initially obtained tetralone complex was achieved via enolate formation followed by protonation.     

Thermodynamic Modeling of the Use of Alkane Mixtures as Working Fluids in Absorption Cycles

The main objective is to show the effect of the choice of the most adequate combination of activity‐fugacity coefficient models on the vapor‐liquid phase equilibrium (VLE) data quality and on the calculation of the enthalpies of the different vapor and liquid streams in a refrigeration absorption machine. Six alkane binary mixtures, i.e. propane or n‐butane as refrigerants and n‐heptane, n‐octane, or n‐decane as absorbents, were considered as working fluids for their proven positive characteristics. Two activity coefficient models, UNIFAC and NRTL, and two equations of state, virial and Peng‐Robinson (PR), were tested. The obtained results showed that the UNIFAC‐PR combination reproduced the VLE data reasonably well; hence, it should be recommended for this type of refrigeration systems operating with alkanes.     

Recycling poly(ethylene terephtalate) wastes: Properties of poly(ethylene terephtalate)/polycarbonate blends and the effect of a transesterification catalyst

The article addresses the issue of recycling of poly(ethylene terephtalate) (PET) by melt blending with polycarbonate (PC). PET/PC blends containing various amounts of the immiscible polymers were prepared in a twin‐screw extruder. Selected compositions were also prepared in the presence of an Sn‐based catalyst to assess the influence of transesterification during melt mixing. The degree of miscibility in the blends was studied using differential scanning calorimetry, scanning electron microscopy, and mechanical testing. PET/PC blends exhibit enhanced tensile properties in comparison to neat components for compositions of PET higher than 50% and these properties are improved by the addition of a transesterification catalyst. The PET/PC blend containing 20 wt% of PC, prepared with stannous octoate, shows the smallest size of the dispersed phase because of transesterification reactions that generate copolymer molecules at the interface between the immiscible polymers. The melting temperature of PET is decreased with the increase of the PC content in blends extruded in the presence of the catalyst. Also, the temperatures of the cold crystallization of PET are higher than those of similar blends without added catalyst. Both features give rise to better molding properties because of a shortening of the cooling time in the range of 50–90 wt% of PET. POLYM. ENG. SCI. 46:1378–1386, 2006. © 2006 Society of Plastics Engineers     

Human platelet antigens polymorphisms and susceptibility of thrombosis in hemodialysis patients

To investigate the association between the polymorphisms of human platelet antigen (HPA)-1,2,3,4,5 and susceptibility to develop thrombosis accident in arteriovenous fistula (AVF), genomic DNA of 112 hemodialysis (HD) patients and 100 healthy blood donors were genotyped by PCR-SSP. The patients were classified into 2 groups: G1 included 54 HD patients presented at least one thrombotic episode on the level of the AVF, and G2 included 58 HD patients without any episode of thrombosis. The allelic frequencies of HPA-1, 2, 3, and 5 among patients and controls did not reveal significant differences. However, the HPA-4b allele was significantly more frequent in G1 than in controls or in G2 patients (23.1% vs. 11.5% and 0.9%, respectively), p<0.01 and p<0.001. The genotype distribution of HPA-4 polymorphism reveals that the HPA-4a4b genotype was more frequent in G1 patients (23/54: 42.6%) than in all HD patients (25/112: 22.3%) or in G2 patients (1/58: 1.72%) (p<0.001, odds ratio: 45.6). Among 24 HD patients with HPA-4a4b genotype, 23 (96%) developed at least 1 or more thrombotic episode on the level of their AVF. However, 30 patients (34.5%) among 87 HD patients with HPA-4a4a genotype presented thrombotic episode (p<0.001). These results reveal a significant association between HPA-4a4b and thrombosis, and it is likely that HPA polymorphisms could be useful markers for potential risk of thrombosis in hemodialysis.     

Effect of the viscosity ratio on the morphology and properties of PET/HDPE blends with and without compatibilization

The influence of the molecular weight of polyethylene on the morphology and mechanical properties of blends of high‐density polyethylene (HDPE) dispersed as droplets in a poly(ethylene terephthalate) (PET) matrix at various compositions was investigated. The difference of morphologies can be easily explained by the influence of the molecular weight on the viscosity ratio and therefore, on the critical capillary number. The compatibilizing efficiency of copolymers containing glycidyl methacrylate groups was also addressed in relation to their nature, the protocol for their drying and the molecular weight of the HDPE phase. The increase of adhesion between PET and HDPE was found to have a larger influence on tensile properties than the reduction of interfacial tension. The amount of compatibilizer needed for adhesion improvement depends on the interfacial area that is defined by both the interfacial tension and viscosity ratio of the components. A qualitative relation between the optimum amount of compatibilizer and the critical capillary number can be written. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Influence of some factors affecting antibacterial activity of PVA/Chitosan based hydrogels synthesized by gamma irradiation

Poly (vinyl alcohol) hydrogels containing different concentrations of chitosan with molecular weight of 471 and 101 kDa were crosslinked by gamma irradiation at a dose of 25 kGy. The swelling behavior, gel content and morphological structure of the blend were investigated. The antibacterial effect, as a function of chitosan content and molecular weight in the hydrogel, was investigated against Escherichia coli and Bacillus subtilis. With increasing chitosan content the equilibrium degree of swelling of the blend increased and the gel fraction decreased. Results of antibacterial activity of chitosan revealed that chitosan was more effective in inhibiting growth of gram positive bacteria than that of gram negative ones. It was observed that, the chitosan content as well as its molecular weight has a direct influence on bacteria growth inhibition. The higher the chitosan content in the blend and the higher its initial molecular weight, the larger was the inhibition zone diameter. The bacteria growth inhibition was attributed to the diffusion of entrapped chitosan from the hydrogel blend to the culture medium.     

Optimal antenna selection based on capacity maximization for MIMO systems in correlated channels

Recent work has shown that multiple-input multiple-output (MIMO) systems with multiple antennas at both the transmitter and receiver are able to achieve great capacity improvement. In such systems, it is desirable to select a subset of the available antennas so as to reduce the number of radio frequency (RF) chains. This paper addresses the problem of antenna selection in correlated channels. We consider a narrowband communication system with M transmit and N receive antennas. We present the criterion for selecting the optimal L/sub t/ out of M transmit and L/sub r/ out of N receive antennas in terms of capacity maximization, assuming that only the long-term channel statistics, instead of the instantaneous channel-state information, are known. Simulations will be used to validate our theoretical analysis and demonstrate that the number of required RF chains can be significantly decreased using our proposed selection strategy, while achieving even better performance than the conventional MIMO system without antenna selection.     

Compact Bat Algorithm with Deep Learning Model for Biomedical EEG EyeState Classification

Electroencephalography (EEG) eye state classification becomes an essential tool to identify the cognitive state of humans. It can be used in several fields such as motor imagery recognition, drug effect detection, emotion categorization, seizure detection, etc. With the latest advances in deep learning (DL) models, it is possible to design an accurate and prompt EEG EyeState classification problem. In this view, this study presents a novel compact bat algorithm with deep learning model for biomedical EEG EyeState classification (CBADL-BEESC) model. The major intention of the CBADL-BEESC technique aims to categorize the presence of EEG EyeState. The CBADL-BEESC model performs feature extraction using the ALexNet model which helps to produce useful feature vectors. In addition, extreme learning machine autoencoder (ELM-AE) model is applied to classify the EEG signals and the parameter tuning of the ELM-AE model is performed using CBA. The experimental result analysis of the CBADL-BEESC model is carried out on benchmark results and the comparative outcome reported the supremacy of the CBADL-BEESC model over the recent methods.     

Simulation numérique des transferts thermiques entre une cavite enterrée et le sol : méthode des fonctions de transfert bidimensionnelles et sous-structuration

Numerical simulation of heat transfer between an earth-sheltered cavity and the soil: two-dimensional transfer functions method and subdivision. This paper describes the use of the two-dimensional transfer functions method for predicting the heat transfer between an earth-sheltered cavity and the surrounding ground. This method is first, applied for the generation of the transfer function coefficients for the system formed by the whole “earth-sheltered cavity–soil”. Then, the latter is decomposed into different layers. Each layer is characterised by its inputs and outputs and by its appropriate transfer functions coefficients. This technique allows a significant reduction in the computation time required to generate the transfer function coefficients of the cavity coupled to the soil. These methods are tested by comparing their results with those of the alternative directions implicit method (ADI) for various situations. The influence of parameters that have large effects on heat transfer such as the cavity depth, the thermal insulation, the nature and the thickness of the cavity walls are studied in typical climates.