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

Continuous Modeling of Arterial Platelet Thrombus Formation Using a Spatial Adsorption Equation

In this study, we considered a continuous model of platelet thrombus growth in an arteriole. A special model describing the adhesion of platelets in terms of their concentration was derived. The applications of the derived model are not restricted to only describing arterial platelet thrombus formation; the model can also be applied to other similar adhesion processes. The model reproduces an auto-wave solution in the one-dimensional case; in the two-dimensional case, in which the surrounding flow is taken into account, the typical torch- like thrombus is reproduced. The thrombus shape and the growth velocity are determined by the model parameters. We demonstrate that the model captures the main properties of the thrombus growth behavior and provides us a better understanding of which mechanisms are important in the mechanical nature of the arterial thrombus growth

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

Сорбенты для экстракорпорального удаления токсических веществ и молекул с нежелательной биологической активностью (обзор)

The review devoted to sorbents and sorbentbased medical devices used in clinical practice for extracorporeal detoxification using a hemoperfusion technique. Clinical data have confirmed the effectiveness of this approach for removal of bacterial endotoxins, lowdensity lipoproteins, and bilirubin. Other studies demonstrated successful application of sorbents to treat autoimmune diseases. Special attention is paid to hemoperfusion in as a possible treatment for severe sepsis and septic shock. The review justifies importance of development and application of novel multimodal sorbents, which combine both properties of selective and nonselective sorbents. The review discusses clinical efficacy of hemoperfusion and key molecular interactions between the sorbent and circulating molecules pathogenetically relevant to developing critical illness and severe diseases. The reference list: 137.В обзоре рассмотрены сорбенты и медицинские изделия на их основе, применяемые в клинической практике для экстракорпоральной детоксикации с помощью процедуры гемосорбции. Представлены данные исследователей, свидетельствующие об эффективности такого подхода с целью удаления бактериальных эндотоксинов, липопротеинов низкой плотности, билирубина, а также при лечении аутоиммунных заболеваний. Основное внимание уделено применению гемосорбции при лечении тяжелого сепсиса и септического шока. Обосновывается необходимость разработки и применения новых «мультимодальных» сорбентов, сочетающих свойства как «селективных», так и «неселективных» сорбентов. В обзоре приведены сведения о клинической эффективности гемосорбции и молекулярном взаимодействии сорбента с циркулирующими молекулами, патогенетически значимыми для развития критических состояний и тяжелых заболеваний. Библиография — 137 ссылок

Performance evaluation of foamed materials based on cold-cured liquid glass

ABSTRACT: Introduction. The current trend of transition to non-combustible and environmentally friendly thermal insulation and sound-absorbing materials involves development of research to obtain foamed silicate compositions, particularly those based on cold-cured liquid glass. The primary advantage of this material is its eco-friendliness throughout both its operational and production stages, facilitated by the employment of energy-efficient manufacturing technology. Materials and methods. Cold-cured liquid sodium glass and cullet-based foam glass were used as main raw materials. To determine optimal curing additive of liquid glass, Portland cement, slaked lime and sodium ethylsilicate were selected. The thermal conductivity of materials was evaluated with by means of appropriate coefficient, value of which depended on volume content of pores in material, nature of porosity and distribution of pores by size. The decrease in water absorption capacity was estimated by value of wetting edge angle. Sorption humidity was determined in accordance with GOST 24816-2014, and sound absorption coefficient was determined according to GOST 16297-80. Results and discussion. The prime objective of this study was to examine trends and provide explanations for the formation of specified performance indicators of thermal insulation and sound-absorbing materials, particularly those based on cold-cured foamed liquid glass. The issue of increasing water resistance of material by selecting effective additive-hardener was also investigated. Conclusion. The developed thermal insulation material based on cold-cured liquid glass is eco-friendly, with presence of large number of small and mainly open pores, giving it good sound-absorbing properties. The problem of high-water absorption of material was solved by introducing Portland cement as a curing additiv

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