Plasticity and decomposition of whiskers on electric-induced deformation

The purpose of the work is to study the influence of weak electric fields (1–10 V/cm) on the micro and macroplasticity of whisker crystals of silver azide. The paper considers the processes occurring in the crystals of silver azide on the indentation in noncontact electric field. One of the processes is the indenter-induced movement of unfixed dislocations, which is the evidence of crystals microplasticity, followed by the accumulation of dislocations at the impediments of different nature. Further, this causes the change in linear dimensions of the crystals and the return to original dimensions, which is the evidence of macroplasticity. After deformation, a greater number of dislocations are formed, which stops the formation of the reaction areas where outgassing is observed. A method for controlling the whiskers stability and reactivity using the microindentation in electric field is proposed

Processing of energy materials in electromagnetic field

This paper presents the research results of complex impact of mechanical stress and electromagnetic field on the defect structure of energy materials. As the object of research quite a typical energy material - silver azide was chosen, being a model in chemistry of solids. According to the experiments co-effect of magnetic field and mechanical stress in silver azide crystals furthers multiplication, stopper breakaway, shift of dislocations, and generation of superlattice dislocations - micro-cracks. A method of mechanical and electric strengthening has been developed and involves changing the density of dislocations in whiskers

Controlling Explosive Sensitivity of Energy-Related Materials by Means of Production and Processing in Electromagnetic Fields

The present work is one of the world first attempts to develop effective methods for controlling explosive sensitivity of energy-related materials with the help of weak electric (up to 1 mV/cm) and magnetic (0.001 T) fields. The resulting experimental data can be used for purposeful alternation of explosive materials reactivity, which is of great practical importance. The proposed technology of producing and processing materials in a weak electric field allows forecasting long-term stability of these materials under various energy impacts

Acute Kidney Injury after Transcatheter Aortic Valve Implantation

Aim. The aim of the study was to evaluate the incidence and predictors of acute kidney injury (AKI) associated with transcatheter aortic valve implantation (TAVI).Material and methods. 50 patients (39 women, 11 men) aged 76 (71; 80) years who underwent TAVI were examined. One day after TAVI, blood creatinine level was determined by the Jaffe method and troponin I by a highly sensitive method (hs-cTnI). Acute kidney injury (AKI) was diagnosed according to the KDIGO criteria (2012). The following hospital complications were evaluated: cases of cardiac death, intraoperative myocardial infarction (MI), stroke and transient ischemic attack, permanent pacemaker implantation, recurrent paroxysms of atrial fibrillation.Results. History of MI had 22% of patients, percutaneous coronary intervention – 38%, hypertension – 98%, chronic kidney disease – 48%, diabetes mellitus – 24%, class II NYHA of chronic heart failure (CHF) – 52%, NYHA class III – 46%, NYHA class IV – 2%. The risk of operational mortality according to EuroSCORE II was 6.3±5.4%. AKI after TAVI was registered in 6 (12%) patients (1 grade AKI – 8%, 2 grade – 2%, 3 grade – 2%). Parameters associated with AKI after TAVI were higher CHF NYHA class (p=0,020), high hs-cTnI level (p=0,013), intraoperative MI (p=0.035). The predictor of AKI after TAVI was high hs-cTnI level (odds ratio 4.0, 95% confidence interval 1.0-16.1). Among patients with AKI after TAVI in compare with patients without AKI, the cumulative frequency of cardiac death, MI, strokes and transient ischemic attacks, implantation of a permanent pacemaker, the proportion of people with paroxysmal atrial fibrillation during the hospital stay was 5,8 times higher (66.7% vs 11.4% respectively, p=0.001).Conclusion. AKI after TAVI was present in 12% of patients. The predictor for AKI development was an increase in hs-cTnI level after TAVI implantation. The hospital prognosis after TAVI is worse in patients with postoperative AKI

Simulation of the Reactivity of Energy Materials in the Technosphere

Methods are proposed for regulating the reactivity of energetic materials that circulate in the technosphere and are not rarely the cause of fires and explosions, both during storage and during transportation. As man-made factors that influence the stability of these materials magnetic and temperature fields and mechanical effects were used. The magnetic field (in the range from 0.01 T to 0.3 T) was used to intensify chemical processes, both at the stage of crystal growth (by the example of silver azide) and together with mechanical action (from 105 Pa to 107 Pa) in the finished crystals. The action of the magnetic field and mechanical stress leads to the stimulation of microplasticity and macroplasticity processes, which are accompanied by a slow decomposition of the samples and subsequent destruction. It was established experimentally that a slight change in storage temperature, as compared to room temperature, accelerates the aging process of samples (range of positive temperatures up to + 30°C), or leads to loss of plasticity (range of negative temperatures down to -20°C) resulting in loss of performance and in loss of useful properties of energy materials

The Effect of Electric Field on the Explosive Sensitivity of Silver Azide

The effect of a constant contactless electric field on the rate of a chemical reaction in silver azide is explored in this paper. The technology of growing and processing silver azide whiskers in the constant contactless electric field (field intensity was varied in the range from 10{-3} V/m to 100 V/m) allows supervising their explosive sensitivity, therefore, the results of experiments can be relevant for purposeful controlling the resistance of explosive materials. This paper is one of the first attempts to develop efficient methods to affect the explosive sensitivity of energy-related materials in a weak electric field (up to 10{-3} V/m)

Role of electronic excitations in explosive decomposition of solids

A combined theoretical and experimental study is performed for the initiation of chemistry process in high explosive crystals from a solid-state physics viewpoint. In particular, we were looking for the relationship between the defect-induced deformation of the electronic structure of solids, electronic excitations, and chemical reactions under shock conditions. Band structure calculations by means of the Hartree-Fock method with correlation corrections were done to model an effect of a strong compression induced by a shock/impact wave on the crystals with and without edge dislocations. Based on the obtained results, an excitonic mechanism of the earliest stages for initiation of high explosive solids is suggested with application to cyclotrimethylene trinitramine (also known as RDX) crystal. Experimental tests of this mechanism for AgN3 decomposition controlled by the dislocation density were worked out. The use of pulse radiolysis techniques allows us to observe pre-explosion modifications in properties and behavior of the solids. Pre-explosion conductivity and pre-explosion luminescence measurements for a series of heavy metal azides lead us to the model for the development of the decomposition chain reaction. Thus, the key role of electronic excitations facilitated by edge dislocations in explosive solids is established and analyzed. Practical applications of the suggested mechanisms are discussed. © 2001 American Institute of Physics