Dynamique Harmonique d'un Couplage Discret/Continu : Application à un Modèle Unidimensionnel de Voies Ferrées

International audienceDans ce papier, on propose d'étudier un modèle simple de voies ferrées en 1D, à l'aide d'une méthode de couplage entre les milieux discrets et continus. Cette méthode de couplage repose sur une partition de la structure en sous domaines. Un domaine modélisé par une approche continue capable de reproduire le même comportement du matériau que celui produit par une approche discrète. Un second domaine est modélisé par une approche discrète où la structure est endommagée. Entre les deux domaines existe un domaine de transition où un raffinement de l'approche continue sera exigé

Studying the Optimum Reaction Conditions for Organic Esterification of Glycerol to Benzoic Acid and Some Devices by Using Ecofriendly Media

The organic esterification reaction of some aromatic carboxylic acids and glycerol in the absence of organic solvents to obtain some α-mono aromate glycerol have been studied. The optimum reaction conditions were determined by esterification of glycerol and benzoic acid to produce α-mono benzoate glycerol (α-MBG). The optimal condition (catalysts and solvents) to get a high selective compounds and high yields have been studied. When use of heterogeneous catalyst (Amberlyst-15) and excess of glycerol (eight time) which plays as a reactive and solvent getting a required selectivity and high yield (about70%) in comparison to the homogeneous catalysts (H2SO4, CH3SO3H), in addition to the low selectivity of the final product. The reaction followed by using thin layer chromatography (T.L.C), the molecular structures have determinate by spectroscopy methods :FT-IR, 1H-NMR, 13C-NMR. Keywords: Glycerol, Benzoic Acid, Esterification Reaction, Amberlyst-15, Ecofriendly Media

The Effect of Flow and Magnetic Twist on Resonant Absorption of Slow MHD Waves in Magnetic Flux Tubes

Observations show that there are twisted magnetic flux tubes and plasma flow throughout the solar atmosphere. The main purpose of this work is to obtain the damping rate of sausage modes in the presence of magnetic twist and plasma flow. We obtain the dispersion relation for sausage modes in slow continuity in an inhomogeneous layer under the conditions of magnetic pores, then we solve it numerically. For the selected density profile, the magnetic field, and the plasma flow as a function of radius across the inhomogeneous layer, we show that the effect of the twisted magnetic field on the resonance absorption at low speed of the plasma flow is greater than one at high speed

Representation of South Asian countries in five high-impact anesthesia journals

Context: The South Asian region is comprised of eight countries, i.e., Pakistan, India, Bangladesh, Sri Lanka, Afghanistan, Bhutan, Nepal, and Maldives. There is dearth of literature documenting anesthesia research in this region.Aim: The aim of this audit was to look at research productivity in the region by examining the volume and the type of anesthesia publication in five high-index anesthesia journals.Settings and Design: The study design was a survey of literature in the top five high-impact anesthesiology journals carried out at a tertiary care hospital.Materials and Methods: The journal citation report 2016 was accessed to identify the top five anesthesia journals based on their impact factor. We identified articles published in these journals between January 2000 and December 2015.Statistical Analysis: Microsoft Excel 2003 worksheet was used for data collection from extracted articles.Results: The highest number of publications came from India (n = 487) 95.9%; 58.5% of these were correspondence, 21% were original articles, 12.8% were case reports and case series, 1.2% reviews, and 1% editorials. Fourteen articles were published from Pakistan, with 1.2% original articles, 0.8% letter to editor, 0.6% audits, and 0.2% case reports. Nepal and Sri Lanka contributed seven publications. There were no publications in these journals from authors from Bangladesh, Afghanistan, Bhutan, and Maldives in the reviewed journals. The highest number of publications was equally distributed between two journals, i.e., Anesthesia and Analgesia (29.5%) and Anesthesia (28.9%).Conclusion: We found that scientific contributions from the South Asian region in terms of original anesthesiology research in five high index anesthesiology journals was suboptimal and has not shown an increasing trend over the last 16 years

Effect of non-cross-linked calcium on characteristics, swelling, drug release and mucoadhesion of calcium alginate beads

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Antibiotic resistance, virulence and genetic diversity of Klebsiella pneumoniae in community- and hospital-acquired urinary tract infections in Iran

Klebsiella pneumoniae is among the most important causes of urinary tract infection (UTI). The aim of this study was to investigate the prevalence and correlation of antibiotic resistance with virulence characteristics and genetic diversity in K. pneumoniae isolated from UTIs in Iran. Phenotypic tests and antibiotic susceptibility were carried out on the isolates. Detection of the virulence and extended-spectrum β-lactamase (ESBL) genes was performed by polymerase chain reaction. Pulsed-field gel electrophoresis (PFGE) was used for exploring the genomic relatedness. Hemolysin, biofilm, and hypermucoviscosity formation were observed in 87.1%, 86.4%, and 12.1% of isolates, respectively. The antibiotic resistance rate of K. pneumoniae isolates ranged from 12.1% for meropenem to 100% for amoxicillin. The prevalence of virulence genes ranged from 1.4% for cnf-1 to 100% for mrkD, fimH, kpn, and entB genes. In this study, 91.7%, 33.3%, and 4.2% of phenotypically ESBL-producers were positive for blaCTX-M, blaTEM, and blaSHV genes, respectively. An association was observed between the presence of traT, fyuA, or cnf-1 genes with antibiotic resistance. Two clone types were obtained by PFGE that indicate different K. pneumoniae clones in community- and hospital-acquired UTIs. The findings of this study are valuable in development of treatment strategies against UTIs in Iran

A coupled discrete/continuous method for computing lattices. Application to a masonry-like structure

International audienceThis paper presents a coupled discrete/continuous method for computing lattices and its application to a masonry-like structure. This method was proposed and validated in the case of a one dimensional (1D) railway track example presented in Hammoud et al. (2010). We study here a 2D model which consists of a regular lattice of square rigid grains interacting by their elastic interfaces in order to prove the feasibility and the robustness of our coupled method and highlight its advantages. Two models have been developed, a discrete one and a continuous one. In the discrete model, the grains which form the lattice are considered as rigid bodies connected by elastic interfaces (elastic thin joints). In other words, the lattice is seen as a ''skeleton'' in which the interactions between the rigid grains are represented by forces and moments which depend on their relative displacements and rotations. The continuous model is based on the homogenization of the discrete model (Cecchi and Sab, 2009). Considering the case of singularities within the lattice (a crack for example), we develop a coupled model which uses the discrete model in singular zones (zones where the discrete model cannot be homogenized), and the continuous model elsewhere. A new criterion of coupling is developed and applied at the interface between the discrete and the continuum zones. It verifies the convergence of the coupled solution to the discrete one and limits the size of the discrete zone. A good agreement between the full discrete model and the coupled one is obtained. By using the coupled model, an important reduction in the number of degrees of freedom and in the computation time compared to that needed for the discrete approach, is observed

Adsorption of Ni(II) ions from aqueous solutions using natural Bentonite

  In this study, natural Syrian bentonite was used from the Tel Rifaat area in Aleppo governorate as a solid phase for adsorption of nickel (ll) ions from aqueous solutions. The coefficient of the distribution of ions on the surface of bentonite was studied in terms of the time of contact (T), the particle size (Vs), the (pH) value of nickel solution and and the solid phase mass (m). Primary concentration effect of the nickel ions was studied and adsorption model was determined. The adsorption experiment was applied to a real produced water sample obtained from tank 247 of the Syrian Oil Transport Company.It was found that the amount of adsorption increases by increasing the contact time from time (1 min ) until reaching the equilibrium time (60 min ). The value of the adsorption until the contact time (24 hours) stay steady. The experiment showed that the amount of adsorption increases by decreasing the particle size of bentonite from the range (1-2) mm until reaching the highest amount of adsorption using the particle size within the range (100 - 250) µm.then, The amount of adsorption decreases until the particle size < (53) µm. The amount of adsorption of the nickel ( ll ) ions increases with pH increase until the range (5-6). After this range, the process of Ion deposition begins. By increasing the bentonite mass, the total removal ratio increases to amaximum value at (2gr/30ml) and the adsorption amount decreases. it was found that the nickel adsorption on the surface of the bentonite follows the Freundlish model. When the experiment was applied to the real water sample, the ratio of nickel removal using raw bentonite was 91.39 ± 0.23%

Assessment of the performance of CHROMagar KPC and Xpert Carba-R assay for the detection of carbapenem-resistant bacteria in rectal swabs: First comparative study from Abu Dhabi, United Arab Emirates

© 2019 International Society for Antimicrobial Chemotherapy Objectives: The objective of this study was to evaluate the performance of CHROMagar™ KPC compared with Xpert® Carba-R assay for the detection of carbapenem-resistant bacterial isolates from rectal swabs. Methods: Rectal swabs were obtained from patients admitted to Cleveland Clinic Abu Dhabi (United Arab Emirates) over a period of 7 months and were screened for carbapenem resistance by either culture on CHROMagar KPC or carbapenemase production using the Xpert Carba-R molecular method. Further testing for carbapenem susceptibility of isolates recovered from CHROMagar KPC was performed using VITEK®2. Results: A total of 1813 rectal swabs were screened, of which 61 (3.4%) were positive for carbapenem resistance by either one or both methods. Both methods were equally efficient in detecting carbapenem resistance in 37/61 swabs (60.7%), mostly positive for Klebsiella pneumoniae (22 isolates), of which 40.9% (9/22) carried blaOXA-48-like and blaNDM. Xpert Carba-R assay detected 12 additional swabs with negative CHROMagar KPC culture and revealed additional carbapenemase-producing organisms carrying blaOXA-48-like and/or blaNDM. CHROMagar KPC recovered organisms in nine swabs not detected by the genotypic method, 44.4% of which were K. pneumoniae. Three swabs yielded false-positive results (carbapenem-susceptible organisms) by both methods. Sensitivity and specificity were, respectively, 75.4% and 99.8% for CHROMagar KPC and 80% and 99.8% for Xpert Carba-R. Conclusion: This comparative study of CHROMagar KPC versus Xpert Carba-R in rectal swabs showed a slightly higher sensitivity for the PCR-based method. Whilst CHROMagar KPC provides a less expensive screening method, Xpert Carba-R may be more accurate and faster