A real-space grid implementation of the Projector Augmented Wave method

A grid-based real-space implementation of the Projector Augmented Wave (PAW) method of P. E. Blochl [Phys. Rev. B 50, 17953 (1994)] for Density Functional Theory (DFT) calculations is presented. The use of uniform 3D real-space grids for representing wave functions, densities and potentials allows for flexible boundary conditions, efficient multigrid algorithms for solving Poisson and Kohn-Sham equations, and efficient parallelization using simple real-space domain-decomposition. We use the PAW method to perform all-electron calculations in the frozen core approximation, with smooth valence wave functions that can be represented on relatively coarse grids. We demonstrate the accuracy of the method by calculating the atomization energies of twenty small molecules, and the bulk modulus and lattice constants of bulk aluminum. We show that the approach in terms of computational efficiency is comparable to standard plane-wave methods, but the memory requirements are higher.Comment: 13 pages, 3 figures, accepted for publication in Physical Review

Fast electrochemical doping due to front instability in organic semiconductors

The electrochemical doping transformation in organic semiconductor devices is studied in application to light-emitting cells. It is shown that the device performance can be significantly improved by utilizing new fundamental properties of the doping process. We obtain an instability, which distorts the doping fronts and increases the doping rate considerably. We explain the physical mechanism of the instability, develop theory, provide experimental evidence, and perform numerical simulations. We further show how improved device design can amplify the instability thus leading to a much faster doping process and device kinetics.Comment: 4 pages, 4 figure

Quasi-steady stages in the process of premixed flame acceleration in narrow channels

The present paper addresses the phenomenon of spontaneous acceleration of a pre-mixed flame front propagating in micro-channels, with subsequent deflagration-to-detonation transition. It has recently been shown experimentally [M. Wu, M. Burke, S. Son, and R. Yetter, Proc. Combust. Inst. 31, 2429 (2007)], computationally [D. Valiev, V. Bychkov, V. Akkerman, and L.-E. Eriksson, Phys. Rev. E 80, 036317 (2009)], and analytically [V. Bychkov, V. Akkerman, D. Valiev, and C. K. Law, Phys. Rev. E 81, 026309 (2010)] that the flame acceleration undergoes different stages, from an initial exponential regime to quasi-steady fast deflagration with saturated velocity. The present work focuses on the final saturation stages in the process of flame acceleration, when the flame propagates with supersonic velocity with respect to the channel walls. It is shown that an intermediate stage may occur during acceleration with quasi-steady velocity, noticeably below the Chapman-Jouguet deflagration speed. The intermediate stage is followed by additional flame acceleration and subsequent saturation to the Chapman-Jouguet deflagration regime. We elucidate the intermediate stage by the joint effect of gas pre-compression ahead of the flame front and the hydraulic resistance. The additional acceleration is related to viscous heating at the channel walls, being of key importance at the final stages. The possibility of explosion triggering is also demonstrated

The blue vibronically resolved electroluminescence of azatrioxa[8]circulene

Organic Light Emitting Dioides (OLED)devices were fabricated with blue emission based on azatrioxa[8]circulene and 4,4-N,N'-Dicarbazolyl-1,1'-biphenyl (CBP) with maximum brightness of 840 kd/m(2) at 12 V and the starting voltage of 3.5 V. The vibronic emission spectrum was analyzed by the promotive modes calculation method. The electroluminescence of fabricated OLED device is caused by the 0-0 electronic transition and single excitations of 1473 cm(-1) and 1673 cm(-1) modes and combinations thereof.Peer reviewe

О сложности верификации недетерминированных вероятностных мультиагентных систем

Probabilistic systems of interacting nondeterministic intelligent agents are consid- ered. States of the agents in these systems are some probabilistic databases, and the activity of the agents is controlled by some probabilistic logic programs. Moreover, com- munication channels between agents are also probabilistic. We show how such systems can be polynomially transformed to ¯nite state Markov decision processes. This allows one to transfer the known results on verifying temporal properties of the ¯nite state Markov processes to the probabilistic multi-agent systems of considered type.Рассматриваются вероятностные системы взаимодействующих недетерминированных интеллектуальных агентов. Состояниями агентов в таких системах являются вероятностные базы данных (фактов), а их действия управляются вероятностными логическими программами. Кроме того, каналы взаимодействий между агентами также являются вероятностными. Показано, как таким системам за полиномиальное время могут быть сопоставлены моделирующие их конечные Марковские процессы принятия решений. Это позволяет перенести известные результаты о верификации динамических свойств конечных Марковских процессов на вероятностные мультиагентные системы рассматриваемого типа

Charge qubit entanglement via conditional single-electron transfer in an array of quantum dots

We propose a novel scheme to generate entanglement among quantum-dot-based charge qubits via sequential electron transfer in an auxiliary quantum dot structure whose transport properties are conditioned by qubit states. The transfer protocol requires the utilization of resonant optical pulses combined with an appropriate voltage gate pattern. As an example illustrating the application of this scheme, we examine the nine-qubit Shor code state preparation together with the error syndrome measurement

Influence of severe plastic deformation on the precipitation hardening of a FeSiTi steel

The combined strengthening effects of grain refinement and high precipitated volume fraction (~6at.%) on the mechanical properties of FeSiTi alloy subjected to SPD processing prior to aging treatment were investigated by atom probe tomography and scanning transmission electron microscopy. It was shown that the refinement of the microstructure affects the precipitation kinetics and the spatial distribution of the secondary hardening intermetallic phase, which was observed to nucleate heterogeneously on dislocations and sub-grain boundaries. It was revealed that alloys successively subjected to these two strengthening mechanisms exhibit a lower increase in mechanical strength than a simple estimation based on the summation of the two individual strengthening mechanisms

Renalase – a new instrument in multicomponent heart failure assessment

Heart failure (HF) remains a serious problem in Russian and world health care due to the growing morbidity and mortality from complications of heart failure, despite the development and implementation of programs for the early detection and treatment of heart failure in asymptomatic patients. Currently, a large number of new biological markers have been studied that could serve as a laboratory tool for diagnosing and predicting the course of heart failure, but only brain natriuretic peptides have found application in real clinical practice. Renalase is a recently discovered cytokine that is synthesized by the kidneys and released into the blood. To date, seven subtypes of renalase have been found, each of which plays a different physiological role in the human body. Renalase is usually positioned as a signaling molecule that activates cytoprotective intracellular signals, leading to a decrease in blood pressure and protection of the heart muscle. The concentration of renalase freely circulating in the bloodstream of an adult is approximately 3–5 ng / ml. Currently, the level of renalase is determined by the enzyme immunoassay with a detection range of 3.12 to 200 ng / ml, while the minimum detectable concentration of the marker is less than 1.38 ng / ml. The presence of missense polymorphism of renalase is associated with myocardial dysfunction. Data from animal and human studies have shown that renalase plays a key role in the metabolism of catecholamines and in cardioprotective processes. Studies have shown the contribution of renalase to the occurrence of cardiovascular diseases: ischemic heart disease, arterial hypertension, diabetes mellitus, and aortic stenosis. Moreover, detailed protocols of multicenter prospective studies have demonstrated that functional polymorphism of the renalase gene was associated with myocardial hypertrophy in patients with aortic stenosis, hypertension, metabolic syndrome, unstable angina pectoris and stable forms of coronary artery disease, as well as in patients receiving renal replacement therapy. Based on these data and further studies, renalase has been proposed as a predictive biomarker of ischemia in patients with coronary microvascular dysfunction, as well as a predictor of clinically significant progression of chronic kidney disease in patients with cardiovascular diseases.Our review presents data on the role of renalase in heart failure. Further study of the structure and function of renalase, as well as future clinical studies, will allow determining the diagnostic, prognostic and, possibly, therapeutic significance of this biological marker in HF and other cardiovascular diseases