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Extended‐spectrum β‐lactamase (ESBL)‐producing Enterobacteriaceae have emerged as important nosocomial pathogens. Community infections by these organisms have been also reported and were associated with previous intestinal colonization. We aimed to characterize cefotaxime‐resistant Enterobacteriaceae (CTX‐R‐En) isolated from hospitalized children in a Tunisian paediatric ward. Seventy CTX‐R‐En isolates were collected from 227 rectal swabs from hospitalized children in a paediatric ward. Antimicrobial susceptibility testing was determined according to the EUCAST guidelines. Isolates were characterized by polymerase chain reaction (PCR, genes encoding: ESBLs, pAmpC, carbapenemases, plasmid‐mediated quinolone resistance, virulence factors in Escherichia coli and Klebsiella pneumoniae isolates, occurrence of classes 1 and 2 integrons, phylogenetic groups of E. coli isolates, ERIC‐PCR and PCR‐based replicon typing) and conjugal transfer experiments. In total, 65 out of 227 (28·6%) hospitalized children were colonized with CTX‐M‐R‐En, and 70 isolates were identified. Isolates were 59 ESBL‐, 7 plasmidic‐AmpC (pAmpC)‐, 3 ESBL+pAmpC‐, and one ESBL+carbapenemase producers. The following bla genes were identified: blaCTX‐M‐15 (n = 54), blaCTX‐M‐1 (n = 5), blaCTX‐M‐9 (n = 2), blaCTX‐M‐13 (n = 1) and blaCTX‐M‐14 (n = 1), blaCMY‐2 (n = 5), blaCMY‐4 (n = 4), blaACC‐1 (n = 1) and blaOXA‐48 (n = 1). Our results showed that hospitalized children were colonized with various CTX‐R‐En‐producing several beta‐lactamase enzymes. [ABSTRACT FROM AUTHOR]

A thermodynamically-consistent large strain viscoelasticity-viscoplasticity-damage Internal State Variable (ISV) constitutive material model integrated with a mixture theory combining each individual constituent is formulated to describe the highly nonlinear, rate-dependent thermomechanical behavior of Fiber Reinforced Polymer (FRP) composites. The model is formulated in an intermediate configuration where unloading the specimen is viscoelastic. In our model, a rate-dependent yield surface is employed to identify initial yielding of the material. At small deformations, which occurs before yielding, the viscoelastic behavior of FRPs is described using the generalized Maxwell model, while at large deformation, three physically based evolving ISVs are used to capture the hardening and softening behaviors caused by their polymeric constituents. The complicated damage state of the FRPs is captured by a second rank tensor, which is further decomposed to model the subscale damage phenomena of microvoids/cracks nucleation, growth and coalescence. Finally, the mixture theory in combination with certain homogenization procedures are adopted to formulate the overall stress, strain, and damage of the composite in terms of the individual constituents. To demonstrate the model's usage, two examples are presented. First, the ISV model is calibrated to a Polyamide 6,6 reinforced with glass fibers with the aim of showing its capacity to predict the viscoelastic and damage coupled behaviors of a composite. Second, a glass fiber reinforced epoxy with the purpose of describing the temperature dependence and the interphase effect is illustrated. [ABSTRACT FROM AUTHOR]

This paper presents a systematic computational study to investigate the effects of crystal orientation, strain rate (impact velocity), and size (thickness) on plasticity and damage behavior of copper single crystals during the penetration process at the atomistic scale. For the penetration analysis, copper single crystals with different crystal orientations and thicknesses were impacted and penetrated by a cylindrical nickel penetrator at different initial velocities. Modified embedded atom method potentials were used to develop atomistic models, and over 250 molecular dynamics simulations were performed to fully reveal the effects of influence parameters on plasticity and damage behavior of the copper single crystals. The results show that the copper single crystal with an octal slip orientation exhibits the greatest strength and penetration resistance, while the copper crystal with the single slip orientation exhibits the lowest strength and resistance. The results further show that the strength and penetration resistance of the target increase as the thickness of the copper single crystals increases. Furthermore, as the impact velocity increases, damage and fragmentation increase. Conclusions drawn from this computational study are consistent with macroscale plasticity theories of metals and reaffirm the conclusions drawn by other researchers in previous experimental studies. [ABSTRACT FROM AUTHOR]

Background: Most patients with idiopathic nephrotic syndrome (NS) are steroid-responsive, about 50% relapse and often become steroid-dependent. The aim of this study was to determine epidemiology, treatment and outcome of children with first episode of NS. Methods: This was a retrospective hospital-based cohort study in the department of pediatric nephrology of Charles Nicolle, Tunis, between 2002 and 2012. It included 52 children with idiopathic NS aged from 1 to 12 years, hospitalized for the first manifestation of the NS and followed for at least one year. Results: The median age of presentation was 5.1±2.5 years. Male to female ratio was 2.7:1. Family history of atopy was found in 14 (26.9%) patients and personal atopy was noted in 9 (17.3%) patients. Microscopic hematuria was seen in 33 (63.5%) patients. The mean blood level of albumin was 1.17±4.2 g/dl, alpha-2 globulin was 1.71±3.5g/dl, cholesterol was 413.7±2.4 mg/dl and the mean proteinuria was 148±70 mg/kg/day. The mean time for first remission was 15.8±2 days. Thirty-eight patients (73%) relapsed and 31 patients (59.6%) became steroid dependent. Total 32 (61.5%) patients recovered from their NS with average interval between the onset of illness and recovery being 3.8±2.1 years (range: 2-10 years). Twenty-two (42.3%) required immunosuppressive drugs such as cyclophosphamide, mycophenolate mofetil and cyclosporine. Thirty-two patients (61.5%) were in remission and off therapy for more than 2 years. The most frequents adverse effects of steroid treatment were growth failure in 22 (42.3%) and osteoporosis in 7 (21.8%) patients. Renal functions remained normal for all patients. Conclusion: The prognosis of idiopathic NS is good but the risk of progression to steroid dependence is high, which exposes these children to complications of long-term corticosteroid therapy. Prospective trials are necessary to identify effective and safe therapies for patients with frequent relapses and steroid dependence. [ABSTRACT FROM AUTHOR]

The microstructure sensitive multistage fatigue model captured the fatigue life of a powder metal FC-0205 steel alloy. Uniaxial strain controlled fatigue data and microstructure information from sets of high and low porosity specimens calibrated the model. Strain-life behaviour depicted that above the plastic strain limit of 0-002 mm mm-1 in the low cycle fatigue regime, where ubiquitous plasticity occurred, the different porosity levels gave distinct, visibly different results. However, specimens tested below the plastic limit in the high cycle fatigue regime, where failure was dominated by local cyclic microplasticity, showed unclear fatigue lives at different porosity levels. Fractography using scanning electron microscopy showed no clear presence of striations; however, asserted striations in powder metal specimens were similar to geometrical features observed on fracture surfaces of monotonically loaded specimens. The experimental and microstructure data calibrated a fatigue model that allowed for satisfactory prediction of the varying porosity specimen strain-life curves. [ABSTRACT FROM AUTHOR]

In an earlier study, the authors presented a characterisation of the FC-0205 Ancorsteel powders containing 0·6 and 1·0% Acrawax to define the evolution of the failure line and cap surface of the modified Drucker/Prager cap model during compaction. Using the results of that study (i.e. FC-0205 material parameters), this paper presents sensitivity and uncertainty analysis of the microstructure-property relationships for powder metallurgy compaction. It is found for all of the responses of interest (the compressibility curve, the interparticle friction, the material cohesion, the cap eccentricity and the elastic modulus) that the most dominant parameter is the initial (or tap) density. It is also observed that the uncertainty in output parameters for the case of 1% wax is much larger than those for the case of 0·6% wax, due to the large uncertainty in the failure stress (in particular, the compressive failure stress). [ABSTRACT FROM AUTHOR]

End stage renal disease (ESRD) in infants has particular features in terms of etiologies and therapeutic modalities. The aim of our study is to describe the etiologies and the ESRD outcomes among Tunisian infants. This retrospective study was conducted over 15 years (from January 1998 to December 31, 2013) in the Pediatric Department at Charles Nicolle Hospital. In total, 157 pediatric patients had ESRD. The mean incidence was 4.25 million children. The study involved 24 infants; the sex ratio was equal to 2. The mean age at diagnosis of ESRD was 8 months (range, 1-21 months). Growth retardation was noticed in 14 patients. The main causes were Congenital Anomalies of the Kidneys and Urinary Tract (9 infants) and hereditary renal disease (9 infants). All patients were treated with peritoneal dialysis; 16 infants presented peritonitis. Mortality rate was about 28%. The leading causes of death were cardiovascular diseases and infections. [ABSTRACT FROM AUTHOR]

The primary goal of this study is to model the anisotropic effect of ductile damage in metal forming processes. To represent the ductile metals, an anisotropic ductile plasticity/damage formulation is considered within the framework of continuum mechanics. The formulation is motivated from fracture mechanisms and physical observations in Al--Si--Mg aluminum alloys with second phases. The ductile damage mechanisms are represented by the classical ductile process of nucleation of voids at inclusions, followed by their growth and coalescence. Functions associated with each mechanism are related to different microstructural parameters. The damage, represented by a second rank tensor, is coupled to the Bammann--Chiesa--Johnson (BCJ) rate-dependent plasticity using the effective stress concept. The constitutive equations are integrated using a trapezoidal implicit scheme and implemented into an explicit finite element code. This implementation is used to predict damage during the forward axisymmetric extrusion of an aluminum bar. This example illustrates the applicability of the model to predict the initiation and the evolution of anisotropic damage in metal forming processes. [ABSTRACT FROM AUTHOR]

Presents an anisotropic ductile damage model based on the fracture mechanisms and physical observations in aluminum alloys. Basis of the damage-plasticity coupling; Mechanisms of the ductile fracture; Analysis of dissipated energy from different irreversible processes.

Fully coupled constitutive equations accounting for isotropic hardening as well as the ductile isotropic damage are implemented into the special purpose finite element code for metal forming simulation. First, the formulation of the fully coupled constitutive equations in the framework of the thermodynamics of irreversible processes with state variables is presented. The associated numerical aspects are then presented and discussed using the implicit integration schemes. The numerical implementation of the damage is made in such a manner that the calculations can be executed with or without damage effect, i.e., coupled or uncoupled calculations. Several numerical results are presented discussing the capability of the model to predict the damage initiation and growth during metal forming processes. For some geometrically simple examples, comparisons between coupled and uncoupled solutions are presented. The proposed methodology is then applied to numerically simulate various metal forming processes in order to predict the damage initiation. [ABSTRACT FROM PUBLISHER]