Impact psychologique de l'horaire de travail et de la participation aux taches familiales chez des couples à double carrière.

The present research examined the joint impact of characteristics of the work schedule and the participation in household work on psychological distress and parental role strain as well as stress crossover. A total of 93 dual-earner couples with at least one child living at home participated. Multiple regression analyses revealed that predictive variables of the psychological distress or the parental role strain differed for men and women and that the parental role strain was related to the psychological distress for both men and women. Results partially support the hypothesis of stress crossover since no characteristics of work schedule of the husband's and wife's were related to parental role strain of the spouses, but women's participation in the children's care was associated with men's higher parental role strain. These results underline the importance of studying strains associated with specific social roles of women and men with respect to effects of both work schedule and family strains related to psychological distress. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Kinetics of PCr to ATP and β-ATP to β-ADP phosphoryl conversion are modified in working rat skeletal muscle after training

Kinetics of phosphoryl transfers from PCr to γ-ATP and from β-ATP to β-ADP were measured by magnetization transfer in an in vivo³¹P NMR experiment in working rat skeletal hind leg muscles. Two groups were examined. One group was submitted to a 6-week training program of treadmill running. The other group was composed of sedentary animals. Metabolic oxidative capacity and mechanical performance were improved greatly by training as shown previously. Phosphoryl transfer of PCr→γ-ATP or β-ATP→β-ADP total fluxes were identical in resting trained and untrained muscles. Under stimulation, the flux of creatine kinase transfer was significantly inhibited by 23% compared with resting level in untrained muscles; by contrast, it was not inhibited and maintained at the high resting level in trained muscles. Thus physiological changes probably linked to a decrease of the production of anions, which could inhibit creatine kinase, were able to maintain creatine kinase flux. The flux of β-ATP to β-ADP transfer were enhanced largely in working muscles from 1.4±0.8 and 2±0.8 at rest to 4±1.6 and 6.6±2.7 mM s⁻¹ for untrained and trained muscles respectively; the effect was more pronounced in trained than in untrained muscles. These results showed an acceleration of phosphoryl turnover in working muscles after training, which could contribute to improve oxidative and mechanical performances. Such kinetic measurements of phosphoryl conversion may provide information on ATP turnover in pathophysiologic situations where ADP accumulates because of impaired ATP synthesis (mitochondrial myopathies, lower perfusion level).     

Solar thermochemical gasification of wood biomass for syngas production in a high-temperature continuously-fed tubular reactor

Biomass gasification is an attractive process to produce high-value syngas. Utilization of concentrated solar energy as the heat source for driving reactions increases the energy conversion efficiency, saves biomass resource, and eliminates the needs for gas cleaning and separation. A high-temperature tubular solar reactor combining drop tube and packed bed concepts was used for continuous solar-driven gasification of biomass. This 1 kW reactor was experimentally tested with biomass feeding under real solar irradiation conditions at the focus of a 2 m-diameter parabolic solar concentrator. Experiments were conducted at temperatures ranging from 1000 °C to 1400 °C using wood composed of a mix of pine and spruce (bark included) as biomass feedstock. This biomass was used under its non-altered pristine form but also dried or torrefied. The aim of this study was to demonstrate the feasibility of syngas production in this reactor concept and to prove the reliability of continuous biomass gasification processing using solar energy. The study first consisted of a parametric study of the gasification conditions to obtain an optimal gas yield. The influence of temperature, oxidizing agent (H₂O or CO₂) or type of biomass feedstock on the product gas composition was investigated. The study then focused on solar gasification during continuous biomass particle injection for demonstrating the feasibility of a continuous process. Regarding the energy conversion efficiency of the lab scale reactor, energy upgrade factor of 1.21 and solar-to-fuel thermochemical efficiency up to 28% were achieved using wood heated up to 1400 °C.     

Hydrogen production by coupling pressurized high temperature electrolyser with solar tower technology

Solar hydrogen production by coupling of pressurized high temperature electrolyser with concentrated solar tower technology is studied. As the high temperature electrolyser requires constant temperature conditions, the focus is made on a molten salt solar tower due to its high storage capacity. A flowsheet was developed and simulations were carried out with Aspen Plus 8.4 software for MW-scale hydrogen production plants. The solar part was laid out with HFLCAL software. Two different scenarios were considered: the first concerns the production of 400 kg/d hydrogen corresponding to mobility use (fuel station). The second scenario deals with the production of 4000 kg/d hydrogen for industrial use. The process was analyzed from a thermodynamic point of view by calculating the overall process efficiency and determining the annual production. It was assumed that a fixed hydrogen demand exists in the two cases and it was assessed to which extent this can be supplied by the solar high temperature electrolysis process including thermal storage as well as hydrogen storage. For time periods with a potential over supply of hydrogen, it was considered that the excess energy is sold as electricity to the grid. For time periods where the hydrogen demand cannot be fully supplied, electricity consumption from the grid was considered. It was assessed which solar multiple is appropriate to achieve low consumption of grid electricity and low excess energy. It is shown that the consumption of grid electricity is reduced for increasing solar multiple but the efficiency is also reduced. At a solar multiple of 3.0 an annual solar-to-H₂ efficiency greater than 14% is achieved at grid electricity production below 5% for the industrial case (4000 kg/d). In a sensitivity study the paramount importance of electrolyser performance, i.e. efficiency and conversion, is shown.     

Multivariate Calibration of Semi‐Synthetic Data Sets: Gun Powder Analysis

Quantitative analysis of multi‐component mixtures such as propellant powders is not trivial since it usually requires separation of the mixture constituents. Multivariate calibration combined to the use of semi‐synthetic data sets can eliminate the need for standard solutions preparation, and therefore allow the rapid determination of mixtures provided no intermolecular interactions occur in the systems. Multivariate compositional analyses of FTIR spectra of low‐vulnerability (LOVA), high‐energy low‐vulnerability (HELOVA) and energetic thermoplastic elastomer (ETPE) propellant powder systems were performed using the partial least‐squares (PLS) regression algorithm. All constituents except ethyl centralite (EC) were quantified. Concentrations were predicted within 1% error for the major component (1,3,5‐trinitro‐1,3,5‐triazacyclohexane or RDX), and within 5% error for the minor components (between 12 and 2% nominally by weight). LOVA, HELOVA, and ETPE gun powder samples concentrations were estimated and compared to expected compositions.     

Moisture Effects on the Material Properties of a Jute/Epoxy Laminate: Impulse Excitation Technique Contribution

Natural fibers have enormous potential and offer many advantages. However, the lack of confidence in their structural performance has limited their wider adoption. Among concerns, include susceptibility to higher water absorption. The aim of this paper is to characterize the impact of the water absorption of jute/epoxy composite material using a new approach. This material has a potential to be used in automobile industries (door panels, dashboards, etc.) and in the civil engineering (skins of the sandwich panels in the building). The method of characterization used is original and based on the impulse excitation approach. The mechanical properties identified are correlated to those obtained by classical methods of characterization such as: three points bending and shear tests. Results show clearly that the rate of water absorption decreases physical (resonant frequency) and mechanical properties (Young’s modulus) of jute/epoxy laminate. At the mass saturation, we recorded a decrease in the proper frequency around 10%, and the Young’s modulus in this case loses 28% to 38% of its initial value. In addition, water bath temperature had an important impact on the coefficient of diffusion as well as on the degradation of mechanical properties.     

Modified DHTT Equipment for Crystallization Studies of Mold Slags

Metallurgical and Materials Transactions B - The double hot thermocouple technique (DHTT) enables simulations of the temperature gradient at near-service conditions during continuous casting of...