Carboxyl terminated polyamide 12 chain extension by reactive extrusion using a dioxazoline coupling agent. Part II: Effects of extrusion conditions

Condensation reactions between a carboxyl terminated polyamide 12 and a dioxazoline carried out by reactive extrusion have been characterized in the first part of this study. In the present paper, we focus on the influence of extrusion conditions on reaction progress. Influences of screw profile, screw speed, barrel temperature and feed rate have been established. The use of a flow computation software permitted confirmation of the importance of thermal and mechanical degradations in the condensation process.     

On causality, responsibility, and blame in marriage: Validity of the entailment model.

Examined the entailment model of attributions in close relationships (F. D. Fincham and T. N. Bradbury, 1987) using structural equation modeling. In this model, judgments of causality lead to judgments of responsibility, which in turn determine judgments of blame. The sample consisted of 206 married or cohabiting couples who completed the Conflict Rating Scale and the Dyadic Adjustment Scale. The path analysis conducted with LISREL VII supported the value of an entailment conceptualization for both self (women and men) and spouse attributions (men only). As hypothesized, for men the paths among causality, responsibility, blame, and marital adjustment confirmed the mediating role of responsibility and blame attributions. For women, small direct pathways leading to marital satisfaction were found, as well as 2 large indirect pathways specified by the entailment model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

La nature et les corrélats de l'attachement au sein des relations de couple.

Studied the relationship between different styles of attachment (i.e., comforting, avoidant, and anxious-ambivalent) and marital adjustment. Ss were 248 heteresexual adults (mean age 36.7 yrs) who had been married or living together for a mean period of 11 yrs. All Ss completed 2 measures of attachment style and a scale assessing dyadic adjustment. Multiple regression analysis was used to determine interactions between attachment style and marital adjustment, and the convergent validity of the 2 measures of attachment style was analyzed. French versions of the Dyadic Adjustment Scale (G. B. Spanier, 1976) and 2 attachment style questionnaires (C. Hazan and P. R. Shaver, 1987) and (M. Mikulincer et al, 1990) were used. (English abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acetylcholinesterase engineering for detection of insecticide residues

To detect traces of insecticides in the environment using biosensors,we engineered Drosophila acetylcholinesterase (AChE) to increaseits sensitivity and its rate of phosphorylation or carbamoylationby organophosphates or carbamates. The mutants made by site-directedmutagenesis were expressed in baculovirus. Different strategieswere used to obtain these mutants: (i) substitution of aminoacids at positions found mutated in AChE from insects resistantto insecticide, (ii) mutations of amino acids at positions suggestedby 3-D structural analysis of the active site, (iii) Ala-scananalysis of amino acids lining the active site gorge, (iv) mutagenesisat positions detected as important for sensitivity in the Ala-scananalysis and (v) combination of mutations which independentlyenhance sensitivity. The results highlighted the difficultyof predicting the effect of mutations; this may be due to thestructure of the site, a deep gorge with the active serine atthe bottom and to allosteric effects between the top and thebottom of the gorge. Nevertheless, the use of these differentstrategies allowed us to obtain sensitive enzymes. The greatestimprovement was for the sensitivity to dichlorvos for whicha mutant was 300-fold more sensitive than the Drosophila wild-typeenzyme and 288 000-fold more sensitive than the electric eelenzyme, the enzyme commonly used to detect organophosphate andcarbamate.     

Multiperspective Approach to Exploring Comprehensive Cause Factors for Interface Issues

The severity of interface issues and the necessity of interface management (IM) have not received adequate recognition from both industry and academia. The understanding of interface issues is still insufficient and the proposed or employed measures are unilateral, which result in unsatisfactory IM performance in construction projects. After establishing IM’s importance in the construction industry, this paper presents a multiperspective approach that systematically explores comprehensive cause factors for various interface issues. From six interrelated perspectives, namely people/participants, methods/processes, resources, documentation, project management, and environment, hierarchical cause factors are identified and presented in a structured way. These cause factors are further converted into a series of interface management and control elements that allow for the development of an object data model and a systematic model-based IM strategy dealing with all interface issues. The multiperspective approach outperforms other research methods that analyze selected interface issues in a loose and isolated way. The findings contribute a holistic view of what causes interface issues as well as provide a solid theoretical basis for practitioners and researchers to seek all-around IM solutions.     

Multispecies in situ monitoring of a static internal combustion engine by near-infrared diode laser sensors

A multispecies near-infrared diode laser spectrometer has been constructed for measurements of carbon monoxide, carbon dioxide, and methane directly in the exhaust of a static internal combustion engine. A wavelength modulation-division multiplexing scheme was implemented for the two distributed feedback diode lasers. Gas concentration variations were observed for changes in operating conditions such as increasing and decreasing the throttle, adjusting the air-fuel ratio, and engine start-up.     

Lattice dynamics of the Zn-Mg-Sc icosahedral quasicrystal and its Zn-Sc periodic 1/1 approximant

Quasicrystals are long-range-ordered materials that lack translational invariance, so the study of their physical properties remains a challenging problem. Here, we have carried out inelastic-X-ray- and neutron-scattering experiments on single-grain samples of the Zn-Mg-Sc icosahedral quasicrystal and of the Zn-Sc periodic cubic 1/1 approximant, with the aim of studying the respective influence of the local order and of the long-range order (periodic or quasiperiodic) on lattice dynamics. Besides the overall similarities and the existence of a pseudo-gap in the transverse dispersion relation, marked differences are observed, the pseudo-gap being larger and better defined in the approximant than in the quasicrystal. This can be qualitatively explained using the concept of a pseudo-Brillouin-zone in the quasicrystal. These results are compared with simulations on atomic models and using oscillating pair potentials, and the simulations reproduce in detail the experimental results. This paves the way for a detailed understanding of the physics of quasicrystals.     

High resolution mapping of surface reduction in ceria nanoparticles

Surface reduction of ceria nano octahedra with predominant {111} and {100} type surfaces is studied using a combination of aberration-corrected Transmission Electron Microscopy (TEM) and spatially resolved electron energy-loss spectroscopy (EELS) at high energy resolution and atomic spatial resolution. The valency of cerium ions at the surface of the nanoparticles is mapped using the fine structure of the Ce M(4,5) edge as a fingerprint. The valency of the surface cerium ions is found to change from 4+ to 3+ owing to oxygen deficiency (vacancies) close to the surface. The thickness of this Ce(3+) shell is measured using atomic-resolution Scanning Transmission Electron Microscopy (STEM)-EELS mapping over a {111} surface (the predominant facet for this ceria morphology), {111} type surface island steps and {100} terminating planes. For the {111} facets and for {111} surface islands, the reduction shell is found to extend over a single fully reduced surface plane and 1-2 underlying mixed valency planes. For the {100} facets the reduction shell extends over a larger area of 5-6 oxygen vacancy-rich planes. This finding provides a plausible explanation for the higher catalytic activity of the {100} surface facets in ceria.