Bearing capacity of damaged reinforced concrete beams strengthened with metal casing

Experimental data on the bearing capacity of damaged reinforced concrete beams with the dimensions of 2000×200×100 mm, reinforced with prestressed metal casings, are presented. Damaging in the form of through normal and crossing inclined cracks, as well as excessive vertical moving of the beam were obtained during previous tests for the effect of high-level transverse alternating loads.The authors of the article have developed a method and equipment for restoring and strengthening damaged reinforced concrete beams using a casing. Beams are manufactured and tested in accordance with the three-level design of an experiment.Previously damaged and reduced to the ultimate (pre-emergency) state, the beams were strengthened with the declared method and equipment, and then retested. New data on the bearing capacity of ordinary and damaged beams, as well as reinforced concrete elements strengthened with casings and tested for the action of transverse forces and bending moments were obtained. The research results are presented in the form of experimental-statistical dependences of the bearing capacity of the support areas, deformability and crack resistance of the investigated elements on the ratio of the most significant design factors and external factors. A comparative analysis of the influence of these factors on the main parameters of the bearing capacity of ordinary as well as previously damaged and then strengthened test beams is carried out.The possibility and appropriateness of using the proposed method of strengthening reinforced concrete beams damaged by through normal and cross-inclined force cracks in the conditions of an existing production has been experimentally proved

Investigation of electrostatic fields by modeling methods

The environment is filled with electrostatic fields of various origins. The negative influence of the electrostatic field requires the provision of electrostatic safety standards. So modeling of electrostatic fields is a topical research task. The electrization of objects is complex, depending on the many parameters process. The article considers the existing methods of studying electrostatic fields. The authors have justified the criterion for assessing the safety of an electrostatic field. The article proposes the developed advanced mathematical model describing the electrization of a complex, multi-layered object. Variable values in the proposed mathematical model are the main characteristics of the materials forming the layers of the modeled object, and the parameters of the condition of the environment. The constructed mathematical model of electrization of a complex object has undergone a successful experimental verification in field trials. Analysis of the experimental data confirmed the expected condition of the system, which is a complex object

Investigation of electrostatic fields by modeling methods

The environment is filled with electrostatic fields of various origins. The negative influence of the electrostatic field requires the provision of electrostatic safety standards. So modeling of electrostatic fields is a topical research task. The electrization of objects is complex, depending on the many parameters process. The article considers the existing methods of studying electrostatic fields. The authors have justified the criterion for assessing the safety of an electrostatic field. The article proposes the developed advanced mathematical model describing the electrization of a complex, multi-layered object. Variable values in the proposed mathematical model are the main characteristics of the materials forming the layers of the modeled object, and the parameters of the condition of the environment. The constructed mathematical model of electrization of a complex object has undergone a successful experimental verification in field trials. Analysis of the experimental data confirmed the expected condition of the system, which is a complex object

Characterization of Strong and Crystalline Polyvinyl Alcohol/Montmorillonite Films Prepared by Layer-by-Layer Deposition Method

The preparation of a high-strength and highly crystalline nanocomposite with a layered structure by the use of layer-by-layer deposition (LbL) method from polyvinyl alcohol (PVOH) and montmorillonite (MMT) platelets is reported. The crystallinity and interactions between the components were studied by the use of Fourier transform infrared spectroscopy (FT-IR), wide angle X- ray diffraction (WAXD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The nanocomposite film structure was investigated by the use of scanning electron microscope (SEM) and atomic force microscopy (AFM). The stiffness of the LbL PVOH/MMT film was significantly higher compared to pure PVOH and conventional PVOH/MMT nanocomposite. The structural and thermal studies on thin PVOH/MMT films indicated the enhanced crystallinity of the polymer

METABOLIC CARDIOPROTECTION: NEW CONCEPTS IN IMPLEMENTATION OF CARDIOPROTECTIVE EFFECTS OF MELDONIUM

Recent studies confirm the need to find means to correct ischemic / reperfusion injury due to the hemodynamic medicine, which are already known do not have the proper cardioprotective effects. Key issue is the possibility of drug effects on the mitochondria of cardiomyocytes that controls the aerobic metabolism and maintenance of ATP admission into cardiomyocytes. Moreover mitochondria are the target of ischemia / reperfusion injury and involved in the cardioprotective mechanism ischemia and pharmacologic pre- and postconditioning. Effect of nitric oxide during ischemic reperfusion directed to mitochondria, is considered as the ultimate goal of cardioprotection. Preconditioning effects is begun from sarcolemmal membrane and then is directed to the cytoplasm through a plurality of stages of enzymes, including nitric oxide synthase (NOS), soluble guanylatecyclase (sGC) and protein kinase G (PKG). Thus, the signal is transmitted to the mitochondria, where it occurs cardioprotection. It is proved that the mitochondria provides protection of the heart against ischemia-reperfusion injury by opening the mitochondrial ATP-sensitive K + channels and by converting the capacity of mitochondria. Metabolic modulation concept can be used in the development of strategies cardioprotection for treatment in ischemic / reperfusion myocardial injury

Learner autonomy in modern higher education

This article deals with the concept of learner autonomy as well as the peculiarities of the use of the learner autonomy-based educational technology in the educational system of Russia. The analysis of the concept of learner autonomy is given basing on the works of both foreign and Russian specialists: the origin of the concept is traced back, different variants of defining the concept are given, and the teacher role in the context of learner autonomy is laid emphasis on. Generalizing the views the authors put forward their own definition of the concept of learner autonomy. The authors also point out the correlation of learner autonomy and the concept of communicative concept proposing their own view of communicative competence structure. Besides, the authors consider the prospect of implementing the learner autonomy-based educational technology into the realm of adaptive learning, which is also topical for modern Russian Education

Hole drilling and milling of magnetic alloys parts by shaped tube electrolytic machining

In this research shaped tube electrolytic machining of drilling and milling of magnetic alloys parts and difficult-to-cut metals, steels and alloys is presented. New research made in the field of space, aviation, automobile, medical, computer and electronics, and others has created the need for small and fine holes with high aspect ratio in these materials. The primary investigations of ECM with the tubular tool electrode are presented. Compared with mechanical machining, shaped tube electrolytic machining (STEM) exhibits an advantage in producing micro-holes with a high aspect ratio and in producing the curved holes. In order to realize the process of electrochemical machining, experimental assembly with the shaped tube tool electrode has been designed and manufactured. Completed researches indicate that this tool electrode has a high potential to machine difficult-to-cut and brittle metals economically and efficiently

EVALUATION OF CARDIOPROTECTIVE EFFECTS OF THE INCRITIN MIMETICS EXENATIDE AND VILDAGLIPTIN IN THE EXPERIMENT

Introduction: The results of experimental and clinical trials make it clear that incretin mimetics possess pleiotropic effects and demonstrate the value in terms of assessment of their potential opportunities as cardioprotectors. Goals: To study the cardioprotective effects of exenatide and vildagliptin on the model of doxorubicin-induced cardiomyopathy. Methods: The experiments on the Langendorf isolated rat heart were dedicated to the study of cardioprotactive activity of exenatide (10 mcg/kg/day) («Byetta®», Eli Lilly and Company, USA) and vildagliptin (0.2 mg/kg/day) («Galvus®», Novartis, Switzerland), on the contractile function of the isolated heart wich was previously perfused with doxorubicin (20 mg/kg, intraperitoneally before 48 hours). The evaluation of cardioprotactive activity was based on the findings of the functional trial with high-frequency stimulation (480 bmp) in hypercalcium (5 mmol) perfusion. The complex evaluation of the myocardial damage in the flowing perfusate from isolated hearts included the assessment of creatine phosphokinase isoenzyme (CPK-MB) and lactic dehydrogenase (LDH). The activity of lipid peroxidation (LPO) was evaluated by measuring the content of malondialdehyde (MDA) and diethenoid conjugant (DC). Results: Exenatide (10 mcg/kg/day) and vildagliptin (0.2 mg/kg/day) demonstrate a cardioprotactive effect on the model of doxorubicin-induced pathology, resulting in a decrease of diastolic dysfunction to 5.3±0.1 units and 6.5±0.2 units respectively, compared to control 8.3±0.1 units. The cardioprotactive effect was confirmed by 27% and 19% decrease in the levels of CPK-MB marker damage, and by 11.8% and 9.6% decrease in LDH levels respectively in exenatide and vildagliptin series, compared to control. The cardioprotactive effect was also confirmed by prevention of accumulation of lipid peroxidation products of MDA and DC in the ventricular myocardium. Conclusion: Exenatide (10 mcg/kg/day) and vildagliptin (0.2 mg/kg/day) decrease diastolic disfunction, resulting in the recovery of the contractile function of the heart, reduction of the “diastole defect” (StТТI), and the decrease in irreversible damages of cardiomyocytes