Resonance Compression of Acoustic Beams in Crystals

The resonant excitation of an intense elastic wave through nonspecular reflection of a special pump wave in a crystal is described. Geometric criteria are found under which mode conversion, when the incident and reflected beams belong to different acoustic branches, coexists with total internal reflection of an acoustic beam. In this case, the entire energy of an incident pump wave is spent on the excitation of a narrow intense reflected beam close in structure to an eigenmode. A consistent choice of orientations of the sagittal plane and crystal surface that excludes the reflection of a parasitic wave of leakage is found. The resonance parameters have been found for a medium with an arbitrary anisotropy. General relations are concretized for monoclinic, orthorhombic, trigonal, tetragonal, cubic, and hexagonal systems. Estimates and illustrations are given for a series of such crystals. The intensity of the reflected beam increases with its narrowing, but its diffraction divergence also increases with this narrowing. Nevertheless, the intensity of the beam can be increased by a factor of 5–10 at sufficiently high frequencies while keeping its divergence at an acceptable level. Amplification by two orders of magnitude can be achieved by compressing the beam in two dimensions through its double reflection

The 35S U5 snRNP is generated from the activated spliceosome during In vitro splicing

Primary gene transcripts of eukaryotes contain introns, which are removed during processing by splicing machinery. Biochemical studies In vitro have identified a specific pathway in which introns are recognised and spliced out. This occurs by progressive formation of spliceosomal complexes designated as E, A, B, and C. The composition and structure of these spliceosomal conformations have been characterised in many detail. In contrast, transitions between the complexes and the intermediates of these reactions are currently less clear. We have previously isolated a novel 35S U5 snRNP from HeLa nuclear extracts. The protein composition of this particle differed from the canonical 20S U5 snRNPs but was remarkably similar to the activated B* spliceosomes. Based on this observation we have proposed a hypothesis that 35S U5 snRNPs represent a dissociation product of the spliceosome after both transesterification reactions are completed. Here we provide experimental evidence that 35S U5 snRNPs are generated from the activated B* spliceosomes during In vitro splicing

National market of reference materials. Curreent state, problems, and development prospects. Part 1. Introduction. Development of the national market of reference materials

The present publication begins a cycle of papers of specialists from the Scientific Methodical Centre at the State Service of Reference Materials for Composition and Properties of Substances and Materials. These papers will be devoted to the problematic issues of forming and developing the national market of reference materials in terms of requirements imposed by the current legislation of the Russian Federation concerning of measurement uniformity assurance, technical regulation and accreditation in the national accreditation system.Publications are aimed at giving the reader an insight into the common practice of development and use of reference materials of various categories, state regulation procedures when producing and using reference materials taking into account modern requirements in the field of metrological assurance and measurement uniformity in Russia and abroad, together with necessity and importance of harmonization in the field of reference materials, as well as some other aspects of this activity.This paper discusses main aspects concerning the state of the reference materials market in the Russian Federation and suggestions on its development taking into account modern requirements. The role of state regulation when creating the national market of reference materials in the Russian Federation is shown. The paper specifies possible directions for reference materials production, meeting modern metrological requirements imposed on measurements in the sphere of the state regulation of measurement uniformity assurance

Design and Testing of Coils for Pulsed Electromagnetic Forming

Abstract Coil design influences the distribution of electromagnetic forces applied to both the blank and the coil. The required energy of the process is usually defined by deformation of the blank. However, the discharge also results in a significant amount of heat being generated and accumulating in the coil. Therefore, EMF process design involves working with three different problems: 1) propagation of an electromagnetic field through the coil-blank system and generation of pulsed electromagnetic pressure in specified areas, 2) high-rate deformation of the blank, and 3) heat accumulation and transfer through the coil with the cooling system. In the current work, propagation of an electromagnetic field in the coil, blank, die and surrounding air was defined using a consistent set of quasi stationary Maxwell equations applying a corresponding set of parameters for each media. Furthermore, a deformation of the blank driven by electromagnetic forces distributed through the volume of the blank was modeled using a solid mechanics equation of motion and the elastic plastic flow theory. During the discharge of capacitors the process was considered to be adiabatic due to the short duration of the pulse, so a heat transfer during the discharge time was neglected. The distribution of electric current density integrated during the discharge process defines the increase of temperature at every element of the coil. The distribution of temperature was calculated as a function of time using the energy conservation law

Mie-driven directional nanocoupler for Bloch surface wave photonic platform

Modern integrated photonic platforms should combine low-loss guiding, spectral flexibility, high light confinement, and close packing of optical components. One of the prominent platforms represents a one-dimensional photonic crystal combined with dielectric nanostructures that manipulate low-loss Bloch surface waves (BSWs). Proper design of nanostructures gives rise to a variety of optical resonances suitable for efficient capturing and controlling light. In this work, we achieve color-selective directional excitation of BSWs mediated by Mie resonances in a semiconductor nanoparticle. We show that a single silicon nanoparticle can be used as a subwavelength multiplexer switching the BSW excitation direction from forward to backward within the 30 nm spectral range with its central wavelength governed by the nanoparticle size. Our work opens a route for the on-demand fabrication of photonic nanocouplers with tailored optical properties and submicron footprint

EXPERIENCE OF APPLICATION OF COMPLEX TREATMENT OF SENILE MACULAR DEGENERATION

Comprehensive treatment of senile macular degeneration, which consists of the introduction of paravasal retinalamine in conjunction with laser-magnitostimulyatsiey more efficient than traditional methods of therapeutic treatment

FUNNEL FLOW OF A NAVIER-STOKES-FLUID WITH POTENTIAL APPLICATIONS TO MICROPOLAR MEDIA

In this paper foundations are laid for a future solution of a fully coupled flow problem for the micropolar medium undergoing structural change in a funnel-shaped crusher. Initially the fundamental equations of micropolar media are revisited and the problem of structural changes of micropolar media moving in a crusher is explained. Then a review of the current state-of-the-art is presented and a necessary extension of the problem is motivated. The need for using numerical methods of fluid mechanics is emphasized. As a prerequisite for the study of the fully coupled initial boundary value 2D-flow problem of a micropolar fluid the funnel flow of a Navier-Stokes fluid is investigated based on an implicit finite difference scheme using the Thomas algorithm. Numerical results for velocities, stresses, and for the pressure dependence of the funnel flow are presented. The correctness of the algorithm is checked by specializing to the case of a flow through a tunnel of constant cross-section under the influence of gravity, for which an analytical solution is available

Investigation on the co-precipitation of transuranium elements from alkaline solutions by the method of appearing reagents

Highly alkaline radioactive waste solutions originating from production of plutonium for military purposes are stored in underground tanks at the U.S. Department of Energy Hanford Site. The purification of alkaline solutions from neptunium and plutonium is important in the treatment and disposal of these wastes. This report describes scoping tests with sodium hydroxide solutions, where precipitation techniques were investigated to perform the separation. Hydroxides of iron (III), manganese (II), cobalt (II, III), and chromium (III); manganese (IV) oxide, and sodium uranate were investigated as carriers. The report describes the optimum conditions that were identified to precipitate these carriers homogeneously throughout the solution by reductive, hydrolytic, or catalytic decomposition of alkali-soluble precursor compounds by a technique called the Method of Appearing Reagents. The coprecipitation of pentavalent and hexavalent neptunium and plutonium was investigated for the candidate agents under optimum conditions and is described in this report along with the following results. Plutonium coprecipitated well with all tested materials except manganese (IV) oxide. Neptunium only coprecipitated well with uranate. The report presents a hypothesis to explain these behaviors. Further tests with more complex solution matrices must be performed

Национальный рынок стандартных образцов. Состояние, проблемы и перспективы развития. Часть 1. Введение. Формирование национального рынка стандартных образцов

The present publication begins a cycle of papers of specialists from the Scientific Methodical Centre at the State Service of Reference Materials for Composition and Properties of Substances and Materials. These papers will be devoted to the problematic issues of forming and developing the national market of reference materials in terms of requirements imposed by the current legislation of the Russian Federation concerning of measurement uniformity assurance, technical regulation and accreditation in the national accreditation system.Publications are aimed at giving the reader an insight into the common practice of development and use of reference materials of various categories, state regulation procedures when producing and using reference materials taking into account modern requirements in the field of metrological assurance and measurement uniformity in Russia and abroad, together with necessity and importance of harmonization in the field of reference materials, as well as some other aspects of this activity.This paper discusses main aspects concerning the state of the reference materials market in the Russian Federation and suggestions on its development taking into account modern requirements. The role of state regulation when creating the national market of reference materials in the Russian Federation is shown. The paper specifies possible directions for reference materials production, meeting modern metrological requirements imposed on measurements in the sphere of the state regulation of measurement uniformity assurance. Настоящая публикация открывает цикл статей специалистов Научного методического центра Государственной службы стандартных образцов состава и свойств веществ и материалов, посвященный проблемным вопросам формирования и развития национального рынка стандартных образцов с позиций требований, предъявляемых действующим законодательством Российской Федерации в области обеспечения единства измерений, технического регулирования и аккредитации в национальной системе аккредитации.Публикации предназначены для ознакомления читателя со сложившейся практикой разработки и применения стандартных образцов различных категорий, процедурами государственного регулирования при изготовлении и применении стандартных образцов с учетом современных требований в области метрологического обеспечения и единства измерений в России и за рубежом, с необходимостью и проблематикой гармонизации в области стандартных образцов и некоторыми другими аспектами этой деятельности.В настоящей статье рассмотрены основные аспекты состояния рынка стандартных образцов Российской Федерации, представлены предложения по его формированию с учетом современных требований. Показана роль государственного регулирования при создании национального рынка стандартных образцов в Российской Федерации. Обозначены возможные направления производства стандартных образцов, отвечающих современным метрологическим требованиям, предъявляемым к измерениям в сфере государственного регулирования обеспечения единства измерений.