The role of tension-compression asymmetry of the plastic flow on ductility and damage accumulation of porous polycrystals

The influence of the tension-compression asymmetry of the plastic flow, due to intrinsic single-crystal deformation mechanisms, on porosity evolution and the overall ductility of voided metallic polycrystals is assessed. To this end, detailed micromechanical finite-element analyses of three-dimensional unit cells containing a single initially spherical cavity are carried out. The plastic flow of the matrix (fully-dense material) is described by a criterion that accounts for strength-differential effects induced by deformation twinning of the constituent grains of the metallic polycrystalline materials. The dilatational response of porous polycrystals are calculated for macroscopic axisymmetric tensile loadings corresponding to a fixed value of the stress triaxiality and the two possible values of the Lode parameter. It is shown that damage accumulation, and ultimately ductility of the porous polycrystals are markedly different as compared to the case when the matrix is governed by von Mises criterion. Most importantly, a direct correlation is established between the macroscopic material parameter k that is intimately related to the particularities of the plastic flow of the matrix and the rate of damage accumulation. (C) 2017 Portuguese Society of Materials (SPM). Published by Elsevier Espana, S.L.U.. All rights reserved.The authors gratefully acknowledge the financial support of the Portuguese Foundation for Science and Technology (FCT) via the project PTDC/EMETEC/1805/2012.This work has been supported by FCT (Fundacao para a Ciencia e Tecnologia) in the scope of the project UID/EEA/04436/2013.info:eu-repo/semantics/publishedVersio

Antibiotic therapy in the treatment of acute otitis media

Department of Otorhinolaryngology, District Hospital of Orhei, the Republic of Moldova, Department of Pharmacology, Dunarea de Jos University of Galati, RomaniaBackground: Acute otitis media is an infection of abrupt onset that usually presents with ear pain. Worldwide acute otitis media affects about 8-11% of people a year. In acute otitis media, antibiotics may speed recovery but may result in side effects. Antibiotics are often recommended in those with severe disease or under two years old. Material and methods: Our study included a retrospective analysis of 117 patients with acute otitis media, whose medical records were examined. The information was analyzed statistically. Results: The results demonstrated an increased involvement of older people and women. The use of antibiotics to treat acute otitis media is determined by Cefazolin in 49-50% cases, Ceftriaxone - 49%, Cefotaxime – 48%, Cefoperazone – 14%, Amoxicillini Clavulanic acid in 16% of cases. Antibiogram was released for 53 patients, and according to it: Cefazolin – 23%, Amoxicilini Clavulanic acid – 15% and the rest were treated with cephalosporin third generation. Conclusions: Depending on severity, the treatment requires the use of antibiotics with broad spectrum. Antibacterial therapy according to antibiogram is contemporary and has the advantage of assessing the appropriate antibiotic

On the effect of the ratio between the yield stresses in shear and in uniaxial tension on forming of isotropic materials

It is generally believed that the choice of the yield criterion used to describe the plastic behaviour of isotropic metallic materials does not affect much the accuracy of the predictions of forming operations. For this reason, the von Mises yield criterion is used for modelling the plastic behaviour. However, according to the von Mises yield criterion, irrespective of the material, the ratio between the yield stresses in simple shear and in uniaxial tension is the same. In this paper, it is presented a numerical study which reveals that even for one of the simplest deep drawing processes, namely the forming of a cylindrical cup, the yielding description influences the predictions of the plastic strains and the final profile of the part. For the description of yielding, an isotropic yield criterion which allows to differentiate between isotropic materials was used. Specifically, this yield criterion involves a parameter α which is expressible solely in terms of the ratio between the yield stresses in shear and in uniaxial tension; for α = 0 it reduces to the von Mises yield criterion. The results of the numerical study are revealing and are believed to provide a new point of view when considering material requirements for drawing performance and models to be used for prediction of the plastic behaviour in deep-drawing processes. From the analysis of the loading paths that the materials experience during the forming of the cup, it appears that the prevalent belief that the yielding properties in the tension-tension quadrant of the yield surface dictate the final profile should be reconsidered. Indeed, the simulations results indicate that for isotropic materials characterized by α > 0 (σT/τY> √ 3), the cup height is greater than for a von Mises material (α = 0), which is higher than the one obtained for materials with α < 0 (σT/τY< √ 3), i.e. lower values of the ratio between the yield stresses in shear and in uniaxial tension lead to greater cup heights. It is shown that this is mainly related to the plastic deformation of the material initially located in the flange region, which is dictated by the shape of the yield surface in the compression-tension quadrant (i.e. normal to the yield surface in the region between uniaxial compression and pure shear stress states).The authors gratefully acknowledge the financial support of the Portuguese Foundation for Science and Technology (FCT) under the projects with reference PTDC/EME-EME/30592/2017 (POCI01–0145-FEDER-030592) and PTDC/EME-EME/31243/2017 (POCI01–0145-FEDER-031243) and by UE/FEDER through the program COMPETE2020 under the project MATIS (CENTRO-01–0145-FEDER000014) and UIDB/00285/2020. JLA and NC gratefully acknowledge partial support for this work from the Air Force Research Laboratory (AFRL) under contract FA8651–08-D-0108/52

Актуальность профилактики тромбоэмболии легочной артерии в пред-, интра- и постоперационном периоде

Catedra Anesteziologie şi Reanimatologie nr. 2, USMF „Nicolae Testemiţanu”The purpose of this article is an informative analysis of the efficiency of prophylaxis of the pulmonary artery trombembolism. Out of 627 patients monitored, 473 had the benefit of a perioperatory tromboprophylaxis, while the other 154 patients got only a postoperatory tromboprophylaxis. The incidence of pulmonary artery trombembolism is 0.48%, this result refers only to patients operated on urgently. The incidence of lethal cases is 0.16%. Pulmonary artery trombembolism incidence varies depending on the combination of predisposing factors. We studied several combined methods of prophylaxis. Priority was the combination of mechanical methods (application of elastic bandages on the legs) with low molecular mass heparins. From observation of the study we determined an increased efficiency using the combination of mechanical methods with Enoxoparine (Klexan) in tromboprophylaxis of patients with moderate and high risk of pulmonary artery trombembolism. The priorities of Enoxoparine, to other low molecular weight heparins do not require the determination of bleeding and clotting time during administration. Also there was no change in platelet count in patients receiving Enoxoparine.Целью данной статьи является информативный анализ эффективности профилактики тромбоэмболии легочной артерии в пред-, интра- и постоперационном периоде. Из 627 обследованных пациентов, 473 больным проводилась, преимущественно, профилактика тромбоэмболии легочной артерии в пред-, интра- и постоперационном периоде, 154 пациентам - только в послеоперационном периоде. Полученный результат заболеваемости тромбоэмболией легочной артерии - 0,48%, относится только к больным, оперированным в срочном порядке. Смертность 0,16% варьирует в зависимости от сочетания предрасполагающих факторов. Было изучено несколько комбинированных методов профилактики. Приоритетным было сочетание механических методов (применение эластичного бинта на ногах) с гепаринами с низкой молекулярной массой. Исследование определялось повышением эффективности использования сочетания механических методов с еноксипарином (Klexan) в профилактике тромбоэмболии легочной артерии у пациентов с умеренным и высоким риском тромбоэмболии легочной артерии. Преимуществом еноксипарина и других низкомолекулярных гепаринов является то, что не требуется определение кровотечения и время свертывания крови во время приема. Также не определяются никакие изменения в количестве тромбоцитов у пациентов, получающих еноксипарин

Neuron-glia crosstalk mediate the neurotoxic effects of ketamine via extracellular vesicles

Background: General anesthetics (GA) are associated with neurodevelopmental abnormalities including cell death, cognitive and behavioral changes. There is now powerful evidence for non-cell autonomous mechanisms in almost every pathological condition in the brain, especially relevant to glial cells, mainly astrocytes and microglia, that exhibit structural and functional contacts with neurons. These interactions were recently reported to occur via the secretion of extracellular vesicles (EVs). Here, we employed primary human neural cells to analyze ketamine effects focusing on the functions of glial cells and their polarization/differentiation state. We also explored the roles of extracellular vesicles (EVs) and different components of the BDNF pathway. Methods: Ketamine effects were analyzed on human neuronal and glial cell proliferation and apoptosis and astrocytic (A1/A2 ) and microglial (M1/M2) cell activation were analyzed. The impact of the neuron-glial cell interactions in the neurotoxic effects of ketamine was analyzed using transwell co-cultures. The role of the brainderived neurotrophic factor (BDNF) pathway, was analyzed using RT-PCR, ELISA western blot and gene silencing. EVs secreted by ketamine-treated cells were isolated, characterized and analyzed for their effects in neuron-glia cell interactions. Data were analyzed using analysis of variance or a Student\u27s t test with correction for data sets with unequal variances. Results: Ketamine induced neuronal and oligodendrocytic cell apoptosis and promoted the expression of proinflammatory astrocytes (A1) and microglia (M1) phenotypes. Astrocytes and microglia enhanced the neurotoxic effects of ketamine on neuronal cells, whereas neurons increased oligodendrocyte cell death. Ketamine modulated different components in the BDNF pathway: decreasing BDNF secretion in neurons and astrocytes while increasing the expression of p75 in neurons and oligodendrocytes. In addition, ketamine treatment increased the lncRNA BDNF-AS levels and the secretion of pro-BDNF secretion. We found an important role of EVs secreted by ketamine-treated astrocytes in neuronal cell death by delivering BDNF-AS. Conclusions: Ketamine neurotoxicity involves both autonomous and non-cell autonomous mechanisms andomponents of the BDNF pathway expressed by neurons and glial cells represent major regulators of ketamine effects. We demonstrated for the first time a role of EVs as important mediators of ketamine effects by the delivery of specific non-coding RNAs. These results may contribute to a better understanding of cellular and molecular mechanisms underlying ketamine neurotoxic effects in humans and to the development of potential approaches to decrease its neurodevelopmental impact

Поражение сердца при саркоидозе

Department of Cardiac Emergency and Rhythm Disorders, Institute of CardiologyCardiac sarcoidosis is a rare but potentially fatal condition that can mimic more common conditions. Recent advances in imaging technology that allow easier detection of cardiac involvement confirm that minimally symptomatic or asymptomatic cardiac involvement is far more prevalent than previously thought. Often the first manifestation of cardiac sarcoidosic is sudden death or a cardiac arrest. Because of the potential life-threatening complications and potential benefit of treatment, all patients diagnosed with sarcoidosis should be screened for cardiac involvement. We studied a 57 year old female patient with acute onset of this illness manifested by recurrent ventricular arrhythmias and progressive heart failure. We confirmed cardiac involvement by magnetic resonance imaging after discovering characteristic mediastinal lymphadenopathy at the high-resolution computed tomography. Corticosteroid treatment and the implantable cardioverter-defibrillator improved the long-term clinical condition. At the end of the 8th month of supervision the patient retained her asymptomatic clinical condition.Поражение сердца при саркоидозе редкое заболевание, но возможность смертельного заболевания могут имитировать частые заболевания. После первых проявлений поражения сердца при саркоидозе возникает внезапная смерть или остановка сердца. Так как это может быть опасным для жизни осложнением и потенциальным эффектом лечения, у всех пациентов с диагнозом саркоидоз может быть поражено и сердце. Возникновение клинических проявлений при поражении сердца в саркоидозе сопровождается неблагоприятным прогнозом. Представлен клинический случай пациентки, 57 лет, без сердечно-сосудистой патологии в анамнезе, с острым началом саркоидоза, проявленным тяжелым поражением сердца, с выраженной дисфункцией левого желудочка и с желудочковой тахиаритмией. Применение кортикостероидной терапии и имплантация дефибриллятора-кардиовертера улучшили состояние пациентки на длительный период времени