Experimental and theoretical study of hydrogen absorption by LaNi3.6Mn0.3Al0.4Co0.7 alloy using statistical physics modeling

A monolayer model treated by statistical physics by means of the grand canonical ensemble has been developed, describing PCT isotherms for absorption of hydrogen by LaNi_3.6Mn_0.3Al_0.4Co_0.7 alloy. This model presents a high correlation with the experimental results. The experimental absorption isotherms are fitted at three temperature different (T = 293 K to T = 313 K). The physicochemical parameters involved in the model were determined from the experimental isotherms by numerical simulation. These parameters, such as two numbers of absorbed atoms per site n₁ and n₂, two receptor site densities N_1M and N_2M, and two energetic parameters, P₁ and P₂ are discussed in relationship with absorption process. The different thermodynamic functions which govern the absorption mechanism such as entropy (S_a), free enthalpy of Gibbs (G) and internal energy (E_int) are derived by statistical physics model calculations.     

Occurrence of multidrug resistance in Campylobacter from Ivorian poultry and analysis of bacterial response to acid shock

The level of antibiotic multiresistance of Campylobacter strains from chicken was evaluated and responses to the bactericidal effects of organic acids were analyzed. Strains (76) isolated from chicken were analyzed for resistance to antibiotics and acid shock. A high strain resistance to fluoroquinolones (ciprofloxacin and nalidixic acid) was observed, with cross resistance to both drugs in 41% of strains. A low resistance was observed for amoxicillin, erythromycin, and gentamicin. Campylobacter jejuni was the most resistant species. Antibacterial activities against multiresistant Campylobacter strains were observed using acetic, citric, and ascorbic acids at minimum bactericidal concentrations (MBC) ranging from 0.3 to 3 mg/mL. Acetic acid was the most efficient acid with the lowest MBC value. However, a contact time of 4 h was required for an efficient effect against Campylobacter contaminated chicken skin. Using organic acids in the poultry production chain can reduce propagation of antibiotic multiresistant strains of Campylobacter.     

Advanced interpretation of hydrogen absorption process in LaMgNi3.6M0.4 (M = Ni,Mn, Al,Co, Cu) alloys using statistical physics treatment

To obtain good economic and environmental benefits, LaMgNi_3.6M_0.4 (M = Al, Mn, Ni, Co, Cu) alloys are investigated for the hydrogen storage. The absorption data of hydrogen in the tested alloys are measured experimentally at 373 K. The hydrogen absorption isotherms are analyzed using three models derived from statistical physics formalism. The adequate model permits to discover significant details about the absorption phenomenon via determining the density of the interstitial sites (D_m), the number of hydrogen atoms per site (n) and the energetic parameter ΔE. The results indicate that multi-atomic (n > 1) and multi-linking (n < 1) phenomena are feasible for hydrogen absorption in LaMgNi_3.6M_0.4 (M = Al, Mn, Ni, Cu, Co) metals. The effects of the substitutions of Ni with Mn, Co, Cu and Al on the hydrogen absorption capacity are investigated. The interaction hydrogen/metal is analyzed by the calculation of the absorption energies. The chemical interaction is the responsible for the hydrogen absorption phenomenon. The contribution of this work is to provide advanced investigations of the hydrogen absorption mechanism in LaMgNi_3.6M_0.4 (M = Al, Mn, Ni, Co, Cu) metals, which are promising alloys for the hydrogen storage.     

使用序批式反应器对灰水进行生物处理

本研究的目的是探讨序批式反应器技术在处理从学生宿舍淋浴器出口处收集的灰水中的应用。当排出水的COD和BOD分别为20mg／L和5mg／L时，SBR的性能是令人满意的。     

Electrical and compositional properties of TaSi2 films

Tantalum silicide (TaSi₂) thin films were sputter deposited on p- and n-type silicon substrates using ultrapure TaSi₂ targets. The TaSi₂/Si samples were annealed in nitrogen or forming gas or oxygen containing steam at temperatures in the range of 400–900°C. The sheet resistances of TaSi₂/Si were measured by four-point probe before and after anneal. The structure of these films was investigated using x-ray diffraction (XRD) methods. It has been found that the sheet resistance decreases with the increase in annealing temperature and also with the increase in film thickness. X-ray diffraction patterns show changes in the morphological structure of the films. Oxidation characteristics of the film have been investigated in the temperature range of 400–900°C in oxygen containing steam ambient. The oxidation time ranged from 0.5 to 1.5 h. No oxide formation of the tantalum silicide films was observed in this investigation. This has been attributed to the high purity of TaSi₂ sputter targets used in the preparation of the films.     

Techniques de calibration et de traitement des signaux pour la mesure de I’efficacite de blindage des cables au moyen de methodes temporelles

The purpose of this paper is to show the influence of the various time domain parameters on the precision of the result in the frequency domain for the determination of the transfer impedance of the coaxial cable. In the first part of the paper the conversion is made through the discrete Fourier transform. The ratio of the spectrum of the cross talk voltage and the spectrum of the disturbing current is computed to obtain the transfer impedance of the cable. In the second part we purpose some techniques for increasing the dynamic range of the characteristic of the transfer impedance. The average and the determination of the Dirac response of the cable are commented on few examples which summarize the main important point of this method.     

Diameter dependence of the apparent tensile modulus of hemp fibres: A morphological,structural or ultrastructural effect?

The aim of this paper is to investigate the origin of the diameter-dependence of Young’s modulus in hemp fibres. In view of the considerable experimental difficulties encountered when determining the 3D morphology of elementary fibres, the influence of the fibre morphology and size on the E-modulus is studied using a mathematical model. An approach based on the 3D elastic theory is used to construct a model of the fibre structure, and to predict its mechanical properties. We clearly show that the modulus is dependent on the size of the lumen and on the outer fibre diameter. This structural effect, induced by the cylindrical geometry, the multi-layered organisation, and the orientation of the cellulose microfibrils only partly explains the large, experimentally determined dispersion of apparent E-modulus, as a function of fibre diameter. Ultrastructural parameters, such as cellulose crystallinity and microfibril angles, are identified to be the main factors involved in this dependence.     

Analysis of intermetallic swelling on the behavior of a hybrid solution for compressed hydrogen storage – Part I: Analytical modeling

This study focuses on the mechanical response of a hybrid solution dedicated to gaseous hydrogen storage. This solution is made of a carbon/epoxy composite overwrapped on a metal liner first coated with intermetallic material. The composite helps to reinforce the structure, while the liner prevents it from any leakage. In case of deficiency, the intermetallic material behaves as a sponge and interrupts the leakage by absorption and micro-cracks reduction. This hybrid solution or this specific use of intermetallic material has never been presented before. The laminate composite is anisotropic, whereas the liner is an elastic–plastic material. The intermetallic is purely thermo elastic and its study is limited to its mechanical contribution. Using these hypotheses, the suggested analytical model provides an exact solution for stresses and strains on the cylindrical section of the hybrid solution submitted to thermomechanical static loading and hydrogen leakage. The swelling effect of the intermetallic on the behavior of the structure is then investigated.     

Removal of tiemonium methylsulfate,from aqueous solutions using activated carbon prepared from date stones

The retention of a pharmaceutical compound, tiemonium methylsulfate (TIM), from aqueous solutions by adsorption onto activated carbon prepared from date stones (AC–DS) was investigated. Physical and chemical characteristics of this material were also determined. Results showed that pH 8 was optimal for TIM adsorption. Among the kinetic models considered, the pseudo-second-order model was the most appropriate to describe experimental data. Regarding adsorption isotherms, it was shown that the Sips model accurately describe the sorption of TIM onto AC–DS with a correlation factor R²?>?0.98. The adsorption capacity of AC–DS was found to be 42.2?mg?g^?1 at 10°C and 60.5?mg?g^?1 at 25°C, confirming its efficiency for the removal of this compound from aqueous solutions. The values of ΔG⁰ and ΔH⁰ confirmed that the adsorption of TIM onto AC–DS was spontaneous and endothermic in nature and hence more effective at high temperatures. An irregular increase in the randomness was suggested at the AC–DS solution interface during the adsorption process for positive values of ΔS⁰.