Morphology and antibacterial properties of plasticized chitosan/metallocene polyethylene blends

In this work, plasticized chitosan-based materials were produced through a molten process. A thermo-mechanical treatment was used to achieve chitosan plasticization in the presence of water, acetic acid, and glycerol. Water and glycerol acted as plasticizers, while acetic acid was used as a solvent and plasticizer for chitosan. The influence of acetic acid total content, chitosan/acetic acid solution ratio, and chitosan/glycerol ratio were examined in this study. The various plasticized compounds were blended with a metallocene polyethylene (mPE) and the morphology, rheological, and antibacterial properties of this novel blend system were examined. It was found that an increase in acetic acid content allowed better chitosan dissolution, while a higher glycerol concentration resulted in improved dispersion of the plasticized chitosan phase in the mPE. Following thermo-mechanical treatment, blends presented good antibacterial properties with a reduction of the number of bacteria (non-pathogenic Escherichia coli) by 2 log(CFU/mL) for the chitosan-containing systems with respect to neat mPE. Mechanical properties of the mPE/plasticized chitosan blends were improved by compatibilization with ethylene vinyl acetate, while antibacterial properties were not affected.     

Review of Les troubles obsessionels compulsifs: Principes, thérapies, applications (2e édition).

Reviews the book, Les troubles obsessionels compulsifs: Principes, thérapies, applications (2e édition) by Martine Bouvard (2006). This book is addressed to clinicians who wish to apply cognitive-behavioral therapy (CBT) to patients suffering from obsessive-compulsive disorder (OCD). There are ten chapters, each one written by different authors according to their respective fields of expertise. The reviewer praises the editor for compiling a comprehensive guide to CBT treatment for OCD, but did not think there was enough of a difference between the 1st and 2nd editions to warrant a new edition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rheological study of crystallization behavior of polylactide and its flax fiber composites

In this work, the isothermal crystallization of compounded polylactide (PLA) and PLA-flax fiber composites was investigated by means of rheometry using small amplitude oscillatory shear (SAOS). The rheological measurements were carried out in parallel plate flow geometry at a crystallization temperature (T _c ) ranging from 110 to 140 °C. In addition, the effect of shear on polylactide crystallization was studied at 140 °C. Rheological behavior in the molten state was employed to predict the initial viscosity in the T _c interval by applying time-temperature superposition, and results were found to be in agreement with experimental values at low crystallization rates. A simple empirical model was also used to determine the crystallization induction time in a wide range of supercooling conditions. The evolution of the complex viscosity under quiescent conditions of the PLA-based flax-fiber composite indicated an enhancement of the rate of crystallization due to the presence of cellulosic fibers, while shear flow effectively accelerated the crystallization of neat PLA. This work shows that rheometry is an accurate technique for analyzing the crystallization behavior of polymers in a temperature range which presents low to very low crystallization rates, which is the case for PLA at T ≥ 130 °C.     

Expression and Sequence Variants of Inflammatory Genes; Effects on Plasma Inflammation Biomarkers Following a 6-Week Supplementation with Fish Oil

(1) Background: A growing body of literature suggest that polymorphisms (SNPs) from inflammation-related genes could possibly play a role in cytokine production and then interact with dietary n-3 fatty acids (FAs) to modulate inflammation. The aim of the present study was to test whether gene expression of selected inflammatory genes was altered following an n-3 PUFA supplementation and to test for gene–diet interactions modulating plasma inflammatory biomarker levels. (2) Methods: 191 subjects completed a 6-week n-3 FA supplementation with 5 g/day of fish oil. Gene expression of TNF-α and IL6 was assessed in peripheral blood mononuclear cells (PBMCs) using the TaqMan technology. Genotyping of 20 SNPs from the TNF-LTA gene cluster, IL1β, IL6 and CRP genes was performed. (3) Results: There was no significant reduction of plasma IL-6, TNF-α and C-reactive protein (CRP) levels after the 6-week fish oil supplementation. TNF-α and IL6 were slightly overexpressed in PBMCs after the supplementation (fold changes of 1.05 ± 0.38 and 1.18 ± 0.49, respectively (n = 191)), but relative quantification (RQ) within the −0.5 to 2.0 fold are considered as nonbiologically significant. In a MIXED model for repeated measures adjusted for the effects of age, sex and BMI, gene by supplementation interaction effects were observed for rs1143627, rs16944, rs1800797, and rs2069840 on IL6 levels, for rs2229094 on TNF-α levels and for rs1800629 on CRP levels (p < 0.05 for all). (4) Conclusions: This study shows that a 6-week n-3 FA supplementation with 5 g/day of fish oil did not alter gene expression levels of TNF-α and IL6 in PBMCs and did not have an impact on inflammatory biomarker levels. However, gene–diet interactions were observed between SNPs within inflammation-related genes modulating plasma inflammatory biomarker levels.     

Shear and extensional properties of short glass fiber reinforced polypropylene

Shear and extensional properties of a commercial short glass fiber reinforced polypropylene were carefully investigated using commercial rheometers and a novel on‐line rheometer. This on‐line slit rheometer, installed on an injection molding press, has been designed to measure the steady shear viscosity, the first normal stress difference, and the apparent extensional viscosity of polymer melts and composites for high strain rates up to 10⁵ s⁻¹ in shear and 200 s⁻¹ in extension. Our results show that the steady‐state viscosity measurements using the on‐line rheometer are in excellent agreement with those obtained using commercial rheometers. The steady‐state and the complex viscosities of the composites were found to be fairly close to that of the matrix, but the Cox‐Merz rule was not verified for the composites at high rates. The elasticity of the composites was found to be equal to that of the polypropylene matrix. The apparent extensional viscosity was obtained from the pressure drop in the planar converging die of the slit rheometer using the analyses proposed by Cogswell [1] and Binding [2]. The extensional viscosity of the polypropylene was found to be much larger than the shear viscosity at low strain rates with a Trouton ratio of about 40 that decreased rapidly with increasing strain rate down to the value of 4 at 200 s⁻¹. The extensional viscosity of the composites was also found to be close to that of the matrix, with values 35 and 5% larger for the 30 and 10 wt% reinforced polypropylenes, respectively. These results are compared with the predictions of the Goddard model [3], which are shown to overpredict our experimental results. POLYM. COMPOS. 26:247–264, 2005. © 2005 Society of Plastics Engineers.     

A three-dimensional construction of the active site (region 507749) of human neutral endopeptidase (EC.3.4.24.11)

A three-dimensional model of the 507–749 region of neutralendopeptidase-24.11 (NEP; E.C.3.4.24.11) was constructed integratingthe results of secondary structure predictions and sequencehomologies with the bacterial endopeptidase thermolysin. Additionaldata were extracted from the structure of two other metalloproteases,astacin and stromelysin. The resulting model accounts for themain biological properties of NEP and has been used to describethe environment close to the zinc atom defining the catalyticsite. The analysis of several thiol inhibitors, complexed inthe model active site, revealed the presence of a large hydrophobicpocket at the S₁' subsite level. This is supported by the natureof the constitutive amino acids. The computed energies of boundinhibitors correspond with the relative affinities of the stereoisomersof benzofused macrocycle derivatives of thiorphan. The modelcould be used to facilitate the design of new NEP inhibitors,as illustrated in the paper.     

Self-compiling compilers: An appraisal of their implementation and portability

Self-compiling compilers are compilers written in the programming language they are made to compile. They constitute a very interesting case of portable programs, and are rapidly gaining in popularity. This paper is an attempt to classify and evaluate the different methods which have been used for writing and transporting such compilers, according to numerous and various criteria. The potential implementor is then given an idea of the important factors to be considered when selecting one of the many implementation methods available. The study is centred around a specific case, the programming language Pascal and its many compilers.     

Conflict, social support and relationship quality: An observational study of heterosexual, gay male and lesbian couples' communication.

Data from 42 heterosexual, 46 gay male, and 33 lesbian couples were used to assess the contribution of conflict and support discussions to relationship quality. Couples completed questionnaires, and videotaped discussions were coded for levels of negative and positive behaviors. Correlations showed that behaviors were associated with relationship quality in the expected directions. Hierarchical linear modeling analyses assessed the unique contributions of individual and dyadic behaviors to the variability of relationship quality. The findings indicated that, beyond the contribution of individual negative behaviors in the conflict task, the variables of dyadic positive behaviors in the conflict task, individual positive behaviors in the support task, and perceived help accounted for unexplained variance in relationship quality. There were no differences between types of couples on levels of behaviors or on their contributions to relationship quality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)