1,932 research outputs found

    Theoretical Description of Pulsed RYDMR: Refocusing Zero-Quantum and Single Quantum Coherences

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    A theoretical description of pulsed reaction yield detected magnetic resonance (RYDMR) is proposed. In RYDMR, magnetic resonance spectra of radical pairs (RPs) are indirectly detected by monitoring their recombination yield. Such a detection method is significantly more sensitive than conventional electron paramagnetic resonance (EPR), but design of appropriate pulse sequences for RYDMR requires additional effort because of a different observable. In this work various schemes for generating spin-echo like signals and detecting them by RYDMR are treated. Specifically, we consider refocusing of zero-quantum coherences (ZQCs) and single-quantum coherences (SQCs) by selective as well as by non-selective pulses and formulate a general analytical approach to pulsed RYDMR, which makes an efficient use of the product operator formalism. We anticipate that these results are of importance for RYDMR studies of elusive paramagnetic particles, notably, in organic semiconductors

    Revisiting the models of vibration screening process

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    This talk presents two approaches for modeling of the vibration screening process. The first approach is analytical. It models the screening process as a diffusion of undersize fraction taking into account the special term for vibration separation (the Brazil nut effect). The talk provides a solution of the corresponding partial differential equation. The solution in turn allows estimation of the screening performance dependence on both deterministic and stochastic factors as well as evaluation of the factors dominance conditions. The talk presents simple evaluation formulae for the screening process performance. The second approach is based on a simulation model. The model deals with monolayer dynamics. Embodying traditional concepts of vibration transportation, the approach introduces some novel techniques of evaluation of the effect of the granular particles shape. Taking into account the particle shape factor may significantly improve the modeling precision for nonspherical particles

    Electron Counting Statistics and Coherent States of Electric Current

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    A theory of electron counting statistics in quantum transport is presented. It involves an idealized scheme of current measurement using a spin 1/2 coupled to the current so that it precesses at the rate proportional to the current. Within such an approach, counting charge without breaking the circuit is possible. As an application, we derive the counting statistics in a single channel conductor at finite temperature and bias. For a perfectly transmitting channel the counting distribution is gaussian, both for zero-point fluctuations and at finite temperature. At constant bias and low temperature the distribution is binomial, i.e., it arises from Bernoulli statistics. Another application considered is the noise due to short current pulses that involve few electrons. We find the time-dependence of the driving potential that produces coherent noise-minimizing current pulses, and display analogies of such current states with quantum-mechanical coherent states.Comment: 43 pages, LaTeX, to appear in the Journal of Mathematical Physics special volume on Mesoscopic Physic

    Inventions of Scientists, Engineers and Specialists From Different Countries in the Area of Nanotechnologies. Part II

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    The article provides an abstract review of patents. The results of creative activity of scientists, engineers and specialists, including inventions in the field of nanotechnology and nanomaterials, being implemented, allow achieving a significant effect in construction, housing and community services, and related sectors of the economy. For example, the invention Ā«Method for liquidphase synthesis of nanostructured ceramic material in the CeO2ā€“Sm2O3 system to create a solid oxide fuel cellĀ» can contribute to the active development of alternative, hydrogen energy. Fuel cells have a wide range of applications ā€“ from batteries in portable electronic devices to large-scale power generation and autonomous use (for example, in remote areas). Power plants based on fuel cells are almost twice as economical as traditional ones. Their efficiency can reach 85%, and the amount of harmful emissions is almost 100 times lower due to the lack of direct chemical contact of the fuel with the oxidizer. The specialists can also be interested in the following inventions in the area of nanotechnologies: method of increasing the tensile strength of fiber composites by means of preliminary modification of carbon fibers with carbon nanotubes and molecules containing amino groups; preparation method of pure silver nanowires; towards safe and sustainable innovation in nanotechnology; method of distribution of carbon-based nanoparticles in the production of nanocomposite unidirectional thermoplastic tapes; device for reducing the impact of vibration and shock effects on the performance of technological equipment; high-density three-dimensional electrically conductive micro- and mesoporous material based on carbon nanotubes and / or low-layer graphenes and a method for its preparation; nanotechnology as a viable alternative for the removal of antimicrobial resistance determinants from discharged municipal effluents and associated watersheds; and others

    Inventions in the Area of Nanomaterials and Nanotechnologies. Part II

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    Introduction. Advanced technologies impress peopleā€™s imagination demonstrating the latest achievements (materials, methods, systems, technologies, devices etc.) that dramatically change the world. This, first of all, concerns nanotechnological inventions designed by scientists, engineers and specialists from different countries. Main part. The article provides an abstract overview of inventions of scientists, engineers and specialists from different countries: Germany, Russia, USA, et al. The results of the creative activity of scientists, engineers and specialists, including inventions in the field of nanotechnology and nanomaterials allow, when introduced to industry, achieving a significant effect in construction, housing and communal services, and related sectors of the economy. For example, the task resolved by the invention Ā«A composition on the basis of oxide nanostructures to provide surface with superhydrophobic propertiesĀ», means to design a new method of obtaining materials with superhydrophobic properties which possess improved performance and functional characteristics which can be applied in various areas: power engineering, electronics, machine-building, construction, ship-building, aviation, aerospace and food industries. The feature of the invention is that the surfaces demonstrate superhydrophobic properties and, as a result of that, their applying allows protecting metal structures, such as power lines, frame structures, roofs, from ice formation and dirtying. The technical result is possible due to the use of composition on the basis of oxide nanostructures to provide surface with superhydrophobic properties. The composition contains tetraethoxysilane and tetraisopropyl titanate as structure-forming agents, hexamethyldisilazane as hydrophobic element, isopropyl alcohol as dissolvent, non-spheric nanocrystal titanium dioxide with particle size from 10 to 50 nm as a grow accelerator of anisotropic structures to provide specified roughness of the surface. The specialist can be also interested in the following inventions in the area of nanotechnologies: a composite heat-conducting material on the basis of nanoliquid, a nanocomposite material on the basis of potassium titanate, a method of obtaining of nanodispersed powders, hybrid supercondenser on the basis of nanosized nickel hydroxide, etc. Conclusion. One of the most challenging tasks the economy of every country faces is to increase industrial competitiveness through technological upgrade. From the side of the state and companies the principal object to control in this process are the people and enterprises dealing with introduction of inventions and new technologie

    Inventions of Scientists, Engineers and Specialists from Different Countries in the Area of Nanotechnologies. Part V

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    Introduction. Advanced technologies impress people\u27s imagination demonstrating the latest achievements (materials, methods, systems, technologies, devices etc.) that dramatically change the world. This, first of all, concerns nanotechnological inventions designed by scientists, engineers and specialists from different countries. Main part. The article provides an abstract overview of inventions of scientists, engineers and specialists from different countries: Russia, USA, China, Belarus, Italy. The results of the creative activity of scientists, engineers and specialists, including inventions in the field of nanotechnology and nanomaterials allow, when introduced to industry, achieving a significant effect in construction, housing and communal services, and related sectors of the economy. For example, the invention Protective coating and method of its application relates to the field of protecting metals from corrosion. To obtain a protective coating, a composition containing an industrial oil with a powder of a phosphorusmodified copper-carbon nanocomposite is applied to the surface of an unalloyed steel and subjected to thermochemical activation by heating for 20 minutes at a temperature of 100-200 degrees C. During the formation of the coating, strong donor-acceptor bonds of iron atoms with phosphorus, which are in the composition of the copper-carbon nanocomposite, are formed. In the course of experiments, it was found that heating samples with a coating of oil with the addition of a phosphorus-modified copper-carbon nanocomposite to 100-200 degrees C increases the chemical activity of the nanocomposite, as a result of which a protective coating forms on the surface, which reduces the corrosion rate depending on the concentration of the modified metal-carbon nanocomposite. by 70-95%. The following inventions in the field of nanotechnology are also of interest to specialists: a method for obtaining a nanostructured surface of a metal workpiece by laser treatment, a device for producing nanodispersed metal oxides, a method for producing a nanostructured composite material based on aluminum, a method for modifying the surfaces of plates of a brazed plate heat exchanger, etc. Conclusion. One of the most challenging tasks the economy of every country face is to increase industrial competitiveness through technological upgrade. From the side of the state and companies the principal object to control in this process are the people and enterprises dealing with introduction of inventions and new technologies

    Inventions in the Area of Nanomaterials and Nanotechnologies. Part I

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    Introduction. Advanced technologies impress peopleā€™s imagination demonstrating the latest achievements (materials, methods, systems, technologies, devices etc.) that dramatically change the world. This, first of all, concerns nanotechnological inventions designed by scientists, engineers and specialists from different countries. Main part. The article provides an abstract overview of inventions of scientists, engineers and specialists from different countries: Germany, Iraq, China, Russia, USA, Ukraine, Sweden, Japan et al. The results of the creative activity of scientists, engineers and specialists, including inventions in the field of nanotechnology and nanomaterials allow, when introduced to industry, achieving a significant effect in construction, housing and communal services, and related sectors of the economy. For example, the invention Ā«Nanomodified building mortarĀ» refers to construction materials and can be used in masonry of ceramic stones, ceramic bricks, hollow bricks in dry and hot climate. The novelty, in respect to the existing construction mortars, is the combination of known components of Portland cement, sand for construction works, amorphous nanomodified silica dioxide, superplasticizer Š”-3, cure retarders of Portland cement, air-entraining resin. The given qualitative and quantitative composition of nanomodified construction mortar makes it possible to obtain the mentioned mixtures in a simple way: for example, in gravity mixer, with evenly distributed components in volume, which is characterized with specified flowability, water-retaining property, controlled hardening period and can be used in dry and hot climate with air temperature up to 40-50Ā°Š”. The following inventions in the field of nanotechnology can also be interesting for specialists: a composition of self-compacting construction concrete on the basis of cement matrix, a method of producing polarization-sensitive nanocomposite film on the basis of copper selenide, a method of producing porous moulded article in the form of insulation plaster layer, a method to obtain amorphous nanostructured diamond-like coating, a method of cement surface modification, a system to produce carbon nanotubes, et al. Conclusion. One of the most challenging tasks the economy of every country faces is to increase industrial competitiveness through technological upgrade. From the side of the state and companies the principal object to control in this process are the people and enterprises dealing with introduction of inventions and new technologies

    Inventions in the Area of Nanotechnologies and Nanomaterials. Part I

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    Introduction. Advanced technologies inspire people by demonstrating the latest achievements (materials, methods, systems, technologies, devices etc.) that dramatically change the world. This, first of all, concerns nanotechnological inventions designed by scientists, engineers and specialists from different countries. Main part. The article provides an abstract overview of inventions of scientists, engineers and specialists from different countries: Germany, Russia, China, USA et al. The results of the creative activity of scientists, engineers and specialists, including inventions in the field of nanotechnology and nanomaterials allow, when introduced to industry, achieving a significant effect in construction, housing and communal services, and related sectors of the economy. For example, the invention Ā«The composition and manufacturing method of non-fired zirconium heat-resistant concreteĀ» refers to the construction materials industry and can be used in the manufacture of products from zirconium non-fired heat-resistant concrete obtained without pre-firing. The purpose of the invention is to increase the thermal resistance at 1300Š¾C, improve the water resistance of non-fired zirconium heat-resistant concrete and the exclusion a technologically complex method of converting the above-mentioned components into nanoscale particles and heat-shock treatment requiring high energy costs. The following inventions in the field of nanotechnology can also be interesting for specialists: a method to obtain multi-layered nanocomposite coating: a method for modifying carbon nanomaterials in nitrogen-containing plasma; a method for regeneration of aerosol filters and protective membranes; a method for obtaining a polymer nanocomposite material with reduced flammability; a robotic complex for obtaining nanostructured chromium coatings; a method for producing hydrogen from methane, a method for forming a combined hydrophilic coating; thermochromic nanoencapsulated material, production method and a product containing such material; a method for obtaining a water-soluble paint-and-lacquer material with photobactericidal activity for applying photobactericidal coatings based on water-soluble paint-and-lacquer materials Šµt al. Conclusion. One of the most challenging tasks the economy of every country face is to increase industrial competitiveness through technological upgrade. From the side of the state and companies the principal object to control in this process are the people and enterprises dealing with introduction of inventions and new technologie

    Inventions of Scientists, Engineers and Specialists from Different Countries in the Area of Nanotechnologies. Part IV

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    Introduction. Advanced technologies impress people\u27s imagination demonstrating the latest achievements (materials, methods, systems, technologies, devices etc.) that dramatically change the world. This, first of all, concerns nanotechnological inventions designed by scientists, engineers and specialists from different countries. Main part. The paper briefly reviews inventions made by scientists, engineers and specialists from different countries: Russia, USA, China, Belarus, Great Britain, Vietnam, Denmark, the Kyrgyz Republic. The application of the results of scientists\u27, engineers\u27 and specialists\u27 investigations, including inventions in the area of nanotechnology and nanomaterials allow achieving significant efficiency in construction, house and communal service, related sectors of economy. For example, the invention A method to modify concrete with complex additive which includes hydrothermal nanoparticles SiO2 and multi-layer carbon nanotubes refers to methods of modifying concrete by introducing combination of nanoparticles with high specific surface into concrete mixture and can be used in production of precast and monolithic parts and structures of buildings and facilities of different purpose. This method of nanomodifying concrete makes it possible to achieve increased mechanical characteristics of concrete: compressive strength (25-77% at the age of 28 days) and bending strength, resistance to damage, Young\u27s mod of elasticity and shearing modulus, density (up to 10%), accelerated hardening at the early age and rate of strength development, decreased water absorbtion ability and improved indicators of porous structure (pore size and pore differential size uniformity), decreased total capillary porosity, increased frost resistance. The specialists can also be interested in the following nanotechnological inventions: a method to obtain polycrystalline diamond films; phase change materials for building construction: an overview of nano-/microencapsulation, solar collector of transpiration type; a method to obtain composition for antimicrobic coating on the basis of silver sulphide associates with molecules of methylene blue; broadband electromagnetic absorbing coating; a method to produce dry building mixtures; self-organizing nanostructures and separation membrane including aquaporin water channels and the methods to produce and use them; a method to obtain nanocrystalline titanium dioxide with anatase structure, etc. Conclusion. One of the most challenging tasks the economy of every country face is to increase industrial competitiveness through technological upgrade. From the side of the state and companies the principal object to control in this process are the people and enterprises dealing with introduction of inventions and new technologies
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