Dehydration and ionic conductance quantization in nanopores

There has been tremendous experimental progress in the last decade in identifying the structure and function of biological pores (ion channels) and fabricating synthetic pores. Despite this progress, many questions still remain about the mechanisms and universal features of ionic transport in these systems. In this paper, we examine the use of nanopores to probe ion transport and to construct functional nanoscale devices. Specifically, we focus on the newly predicted phenomenon of quantized ionic conductance in nanopores as a function of the effective pore radius - a prediction that yields a particularly transparent way to probe the contribution of dehydration to ionic transport. We study the role of ionic species in the formation of hydration layers inside and outside of pores. We find that the ion type plays only a minor role in the radial positions of the predicted steps in the ion conductance. However, ions with higher valency form stronger hydration shells, and thus, provide even more pronounced, and therefore, more easily detected, drops in the ionic current. Measuring this phenomenon directly, or from the resulting noise, with synthetic nanopores would provide evidence of the deviation from macroscopic (continuum) dielectric behavior due to microscopic features at the nanoscale and may shed light on the behavior of ions in more complex biological channels.Comment: 13 pages, 10 figure

A Finite-Size Scaling Study of a Model of Globular Proteins

Grand canonical Monte Carlo simulations are used to explore the metastable fluid-fluid coexistence curve of the modified Lennard-Jones model of globular proteins of ten Wolde and Frenkel (Science, v277, 1975 (1997)). Using both mixed-field finite-size scaling and histogram reweighting methods, the joint distribution of density and energy fluctuations is analyzed at coexistence to accurately determine the critical-point parameters. The subcritical coexistence region is explored using the recently developed hyper-parallel tempering Monte Carlo simulation method along with histogram reweighting to obtain the density distributions. The phase diagram for the metastable fluid-fluid coexistence curve is calculated in close proximity to the critical point, a region previously unattained by simulation.Comment: 17 pages, 10 figures, 2 Table

Electron-beam modification of coating-aluminum substrate systems

Multiphase surface alloys with improved strength and tribological characteristics have been synthesized by exposing coating/A7 substrate systems to a pulsed electron beam. Optimum modes of electron-ion-plasma treatment of commercially pure aluminum have been found at which the wear resistance and hardness of the surface layer were observed to increase by a factor of about 7.5 and up to 18, respectively

Influence of Phase Diffuser Dynamics on Scintillations of Laser Radiation in Earth Atmosphere: Long-Distance Propagation

The effect of a random phase diffuser on fluctuations of laser light (scintillations) is studied. Not only spatial but also temporal phase variations introduced by the phase diffuser are analyzed. The explicit dependence of the scintillation index on finite-time phase variations is obtained for long propagation paths. It is shown that for large amplitudes of phase fluctuations, a finite-time effect decreases the ability of phase diffuser to suppress the scintillations.Comment: 15 pages, 4 figure

Tomosyn inhibits synaptic vesicle priming in Caenorhabditis elegans

Caenorhabditis elegans TOM-1 is orthologous to vertebrate tomosyn, a cytosolic syntaxin-binding protein implicated in the modulation of both constitutive and regulated exocytosis. To investigate how TOM-1 regulates exocytosis of synaptic vesicles in vivo, we analyzed C. elegans tom-1 mutants. Our electrophysiological analysis indicates that evoked postsynaptic responses at tom-1 mutant synapses are prolonged leading to a two-fold increase in total charge transfer. The enhanced response in tom-1 mutants is not associated with any detectable changes in postsynaptic response kinetics, neuronal outgrowth, or synaptogenesis. However, at the ultrastructural level, we observe a concomitant increase in the number of plasma membrane-contacting vesicles in tom-1 mutant synapses, a phenotype reversed by neuronal expression of TOM-1. Priming defective unc-13 mutants show a dramatic reduction in plasma membrane-contacting vesicles, suggesting these vesicles largely represent the primed vesicle pool at the C. elegans neuromuscular junction. Consistent with this conclusion, hyperosmotic responses in tom-1 mutants are enhanced, indicating the primed vesicle pool is enhanced. Furthermore, the synaptic defects of unc-13 mutants are partially suppressed in tom-1 unc-13 double mutants. These data indicate that in the intact nervous system, TOM-1 negatively regulates synaptic vesicle priming. © 2006 Gracheva et al

Трансформация правового регулирования налоговых отношений в условиях цифровой экономики

The subject. The modern world is constantly changing, which makes it necessary to update the means and methods of legal regulation of public relations. Moreover, these relations themselves are changing, new areas of public relations are emerging, for which it is necessary to create a legal framework. The sphere of financial and legal regulation is no exception. The most important issue, which has been on the agenda of the international community for several years, is the development of the digital economy. The legal realities of digitalization largely determine what place the Russian economy will occupy in the emerging global digital market. It is necessary to develop a comprehensive legal concept that allows ensuring compliance with the fiscal interests of the state in the context of digital transformation. In this regard, the transformation of tax relations and their legal regulation is particularly important.Purpose of the study. The article is devoted to the transformation of the legal regulation of tax relations in the digital economy. In order for Russian financial and legal regulation to contribute to an effective response to the challenges posed by digitalization, it is necessary to develop a comprehensive legal concept that allows ensuring compliance with the fiscal interests of the state in the context of digital transformation. In this regard, the transformation of tax relations and their legal regulation is of particular importance.Methodology. The research was carried out with the application of the formally legal interpretation of legal acts as well as the comparative analysis of Russian and European legal literature. Structural and systemic methods are also the basis of the research. The main results. The necessity to develop legal solutions in the field of taxation of the digital economy is determined by the focus on legal support for the stability of financial and legal regulation and the principle of certainty of taxation. In these circumstances, it is important to implement the control function of financial law. The need to ensure compliance with the fiscal interests of the state, both at present and in the long term, requires the transformation of essential approaches to the legal regulation of the system of taxes and fees, the principles and elements of taxation, tax administration and tax control. In this regard, it is proposed to provide for special rules for calculating and paying income tax on foreign digital companies and, in parallel, to expand tax incentives for Russian companies.Сonclusions. The authors come to the conclusion that the actual scientific task is to develop a methodological position on the directions of reforming the national tax legislation and the international tax doctrine of the Russian Federation in the context of the digital transformation of public relations. According to the results of the study, it is concluded that it is necessary to ensure compliance with the fiscal interests of the state. This requires the transformation of essential approaches to the legal regulation of tax relations, both in the context of determining the appropriate legal forms for regulating the tax base levied in Russia in the context of the emerging digital economy, and for influencing international tax policy in order to use all the advantages provided by international tax cooperation and neutralize the threats caused by international tax competition.Рассматривается трансформация правового регулирования налоговых отношений в условиях цифровой экономики. Актуальной научной задачей объявляется выработка методологической позиции относительно направлений реформирования национального налогового законодательства и международной налоговой доктрины Российской Федерации в условиях цифровой трансформации общественных отношений. По итогам исследования делается вывод о необходимости обеспечения соблюдения фискальных интересов государства, что требует трансформации сущностных подходов к правовому регулированию налоговых отношений как в контексте определения надлежащих правовых форм для регламентации налоговой базы, облагаемой в России, в условиях формирующегося цифрового уклада экономики, так и для воздействия на международную налоговую политику с целью использования всех преимуществ, предоставляемых международной налоговой кооперацией, и нейтрализации угроз, вызываемых международной налоговой конкуренцией. В этой связи предлагается предусмотреть специальные правила исчисления и уплаты налога на прибыль иностранных цифровых компаний и параллельно расширять меры налогового стимулирования российских компаний

ЮМОР В ПРОСТРАНСТВЕ ПОЛИТИЧЕСКОГО: К ПОСТАНОВКЕ ПРОБЛЕМЫ

This article is devoted to posing the problem of humor in the political space, which, being one of the manifestations of social communication, has a number of its features. It also examines the specifics of understanding humor and comic, and explains the appropriateness of ignoring the latter in scientific research. At the same time, emphasis is placed on the fact that a greater scientific perspective in the study of humor in the space of political, for objective reasons, has the use of humor by politicians themselves in the course of their activities as having a more serious consequence both for their image and for the whole community.Настоящая статья посвящена постановке проблемы юмора в пространстве политического, которое, являясь одним из проявлений социальной коммуникации, имеет ряд своих особенностей. В ней также рассматривается специфика понимания юмора и комического и объясняется целесообразность игнорирования второго в научном исследовании. При этом акцент делается на том, что большей научной перспективой при изучении юмора в пространстве политического, в силу объективных причин, обладает использование юмора самими политиками в процессе своей деятельности как имеющее более серьезное последствие и для их имиджа, и для всего сообщества

Optimized sensorless control systems for cargo movement mechanisms

THE PURPOSE. Investigation of the control system of the cargo movement mechanism when using different variants of sensorless control. The search for the optimal option, in which the formation of the speed is identical to the data obtained from the speed sensor. Analysis of the results obtained during the study, including the results obtained taking into account the heating of the motor windings. METHODS. The tasks set during the research are implemented by simulation modeling using the Matlab Simulink computer simulation environment. RESULTS. The article considers systems with different types of velocity observers. A system is implemented that takes into account the heating of the stator and rotor windings of an asynchronous motor, in which a non-adaptive observer and different types of neural network controller were introduced. A combined method of using neural network regulators is proposed. CONCLUSION. Sensorless control systems are relevant for use in industries with the presence, according to the conditions of the technological process, of high temperatures. The conducted research has shown that the use of neural network technologies allows you to work with settings of different levels and types. The proposed method, implying the use of joint work of neural network observers with various neurostructures, allows for speed testing in the entire range. The connection with cloud storage present in the proposed structure leads to the unloading of the management system, allowing to increase the process of analyzing data coming from the object.publishe

Electrically tunable solid-state silicon nanopore ion filter

We show that a nanopore in a silicon membrane connected to a voltage source can be used as an electrically tunable ion filter. By applying a voltage between the heavily doped semiconductor and the electrolyte, it is possible to invert the ion population inside the nanopore and vary the conductance for both cations and anions in order to achieve selective conduction of ions even in the presence of significant surface charges in the membrane. Our model based on the solution of the Poisson equation and linear transport theory indicates that in narrow nanopores substantial gain can be achieved by controlling electrically the width of the charge double layer