Effect of heat treatment on the structural parameters and magnetic properties of copper ferrite nanopowders obtained by the sol-gel combustion

Phase composition, structure parameters and basic magnetic characteristics obtained by the sol-gel combustion nanopowders of ferrospinel CuFe2O4 are investigated. A comparison of the properties of synthesized materials: first sample - immediately after the combustion of the gel and second sample - after annealing at 1073 K for 4 hours are performed. Annealing leads to an increase in the concentration of the phase with tetragonal crystal structure. Particle sizes and the value of anisotropy field of this phase also increased

New Multithreaded Hybrid CPU/GPU Approach to Hartree−Fock

In this article, a new multithreaded Hartree–Fock CPU/GPU method is presented which utilizes automatically generated code and modern C++ techniques to achieve a significant improvement in memory usage and computer time. In particular, the newly implemented Rys Quadrature and Fock Matrix algorithms, implemented as a stand-alone C++ library, with C and Fortran bindings, provides up to 40% improvement over the traditional Fortran Rys Quadrature. The C++ GPU HF code provides approximately a factor of 17.5 improvement over the corresponding C++ CPU code

Computational Physics on Graphics Processing Units

The use of graphics processing units for scientific computations is an emerging strategy that can significantly speed up various different algorithms. In this review, we discuss advances made in the field of computational physics, focusing on classical molecular dynamics, and on quantum simulations for electronic structure calculations using the density functional theory, wave function techniques, and quantum field theory.Comment: Proceedings of the 11th International Conference, PARA 2012, Helsinki, Finland, June 10-13, 201

Structure parameters and magnetic properties of nanosized strontium hexaferrite prepared by the sol-gel combustion method

The phase composition, structure parameters, and main magnetic characteristics of SrFe12O19 hexaferrite prepared by the sol-gel combustion method in combination with subsequent annealing at the temperature of 850°C for 6 hours are investigated. From the study of the magnetization curves in the pulsed magnetic fields the value of saturation magnetization of synthesized material was determined. The value of the magnetocrystalline anisotropy field was determined from the survey of the ferromagnetic resonance

CUDA Implementation of a Navier-Stokes Solver on Multi-GPU Desktop Platforms for Incompressible Flows

Graphics processor units (GPU) that are traditionally designed for graphics rendering have emerged as massively-parallel co-processors to the central processing unit (CPU). Small-footprint desktop supercomputers with hundreds of cores that can deliver teraflops peak performance at the price of conventional workstations have been realized. A computational fluid dynamics (CFD) simulation capability with rapid computational turnaround time has the potential to transform engineering analysis and design optimization procedures. We describe the implementation of a Navier-Stokes solver for incompressible fluid flow using desktop platforms equipped with multi-GPUs. Specifically, NVIDIA’s Compute Unified Device Architecture (CUDA) programming model is used to implement the discretized form of the governing equations. The projection algorithm to solve the incompressible fluid flow equations is divided into distinct CUDA kernels, and a unique implementation that exploits the memory hierarchy of the CUDA programming model is suggested. Using a quad-GPU platform, we observe two orders of magnitude speedup relative to a serial CPU implementation. Our results demonstrate that multi-GPU desktops can serve as a cost-effective small-footprint parallel computing platform to accelerate CFD simulations substantially. I. Introductio

Biological Activity of Soil in Scots Pine Stands with Varying Degrees of Crown Closure

На биологическую активность почвы оказывают влияние многочисленные факторы, такие как гидротермический режим, кислотность, физические и агрохимические свойства почвы и др. В древесных насаждениях к таким факторам можно также отнести степень сомкнутости крон. В статье представлены данные о показателях биологической активности почвы (количество микроорганизмов и активность почвенных ферментов) в насаждениях сосны обыкновенной (Pinus sylvestris L.) различной степени сомкнутости крон. Исследования проводили на территории Кузбасского ботанического сада, расположенного в левобережной части города Кемерово, в прибрежной части реки Томи (район озера Суховского) к востоку от существующих и проектируемых ансамблей развивающегося общегородского центра. Объект исследования – почва в насаждениях P. sylvestris II класса возраста (28–35 лет) разной степени сомкнутости лесного полога: редкосомкнутые (20–30 %), среднесомкнутые (50–60 %) и высокосомкнутые (80–90 %). На каждом участке установлены подкроновые и прикроновые (межкроновые) зоны, на редкосомкнутых площадках наблюдения также установлена внешняя зона. Исследуемая почва не относится к загрязненной, имеет нейтральную реакцию среды и среднее содержание подвижных соединений фосфора и калия. Проведенные исследования показали, что численность почвенных микроорганизмов зависит от влажности почвы. Выявлены отдельные тенденции зависимости биологической активности от степени сомкнутости сосновых насаждений: наибольшее содержание инвертазы и протеазы наблюдалось в редко- и среднесомкнутых насаждениях сосны в подкроновой зоне. Почва высокосомкнутых насаждений в прикроновой зоне наиболее богата микроорганизмами, утилизирующими органические формы азота, и микроорганизмами, разлагающими минеральные формы азотаThe biological activity of soil is influenced by numerous factors, such as hydrothermal regime, acidity, physical and agrochemical properties of the soil, etc. In tree stands, such factors can also include the degree of crown closure. The present study reports data on indicators of biological activity of the soil: the abundance of microorganisms and the activity of soil enzymes in stands of Scots pine (Pinus sylvestris L.) with various degrees of crown closure. The research was carried out in the Kuzbass Botanical Garden, located in the left-bank part of the city of Kemerovo, along the riverside of the Tom River (near Lake Sukhovsky), east of the existing and future ensembles of the developing city center. The material of the study was soil in P. sylvestris stands of age class 2 (28–35 years) with different degrees of closure of the crown canopy: sparsely closed (20–30 %), medium–closed (50–60 %), and highly closed (80–90 %). Under-crown and inter-crown zones were established on each site, and an external zone was additionally established on sparsely closed study site. The soil was not polluted, had a neutral reaction of the medium, and contained average amounts of mobile phosphorus and potassium compounds. The study showed that the abundance of soil microorganisms was determined by soil moisture content. The following trends were revealed in the relationship between biological activity and the degree of closure of pine stands: the highest content of invertase and protease was observed in the under-crown zone of the sparsely and medium-closed pine stands. The soil in the inter-crown zone of highly closed stands was the most abundant in microorganisms that utilize organic forms of nitrogen and microorganisms that decompose mineral forms of nitroge

PLASTER BINDING

FIELD: methods of production of composition plaster bindings.SUBSTANCE: the invention is pertaining to methods of production of composition plaster bindings on the basis of a technical (high-strength) plaster, slag and milled unslaked lime, which combine a fast setting and solidification with a capability to solidify in humid conditions. The plaster binding on the basis of a technical plaster, slag and milled unslaked lime in the capacity of a slag contains an arenaceous ferrochrome slag at the following components ratio, in mass %: the technical plaster - 70-85, the arenaceous ferrochrome slag - 15-25, milled unslaked lime - 0-5. The technical effect - an accelerated solidification of the composition and increase of its water-resistance by 10-30 %, simplification of the process of a binding production, decreased capital input, reduced cost of binding, utilization of ferrochrome slag.EFFECT: the invention ensures accelerated solidification of the plaster binding composition, increased its water-resistance, simplification of the binding production process, decreased capital input, reduced cost of binding production, utilization of ferrochrome slag.1 tbl.Изобретение относится к технологиям получения композиционных гипсовых вяжущих на основе технического (высокопрочного) гипса, шлака и молотой негашеной извести, которые сочетают скоростное схватывание и твердение со способностью твердеть во влажных условиях. Гипсовое вяжущее на основе технического гипса, шлака и молотой негашеной извести в качестве шлака содержит рассыпающийся феррохромовый шлак при следующем соотношении компонентов в мас.%: технический гипс - 70-85, рассыпающийся феррохромовый шлак - 15-25, молотая негашеная известь - 0-5. Технический результат - ускорение твердения композиции и повышение ее водостойкости на 10-30%, упрощение технологической схемы получения вяжущего, уменьшение капитальных затрат, снижение стоимости вяжущего, утилизация феррохромового шлака. 1 табл

Ab Initio Screening Approach for the Discovery of Lignin Polymer Breaking Pathways

The directed depolymerization of lignin biopolymers is of utmost relevance for the valorization or commercialization of biomass fuels. We present a computational and theoretical screening approach to identify potential cleavage pathways and resulting fragments that are formed during depolymerization of lignin oligomers containing two to six monomers. We have developed a chemical discovery technique to identify the chemically relevant putative fragments in eight known polymeric linkage types of lignin. Obtaining these structures is a crucial precursor to the development of any further kinetic modeling. We have developed this approach by adapting steered molecular dynamics calculations under constant force and varying the points of applied force in the molecule to diversify the screening approach. Key observations include relationships between abundance and breaking frequency, the relative diversity of potential pathways for a given linkage, and the observation that readily cleaved bonds can destabilize adjacent bonds, causing subsequent automatic cleavage.Massachusetts Institute of Technology (Research Support Corporation, Reed Grant)United States. Dept. of Energy. Computational Science Graduate Fellowship Program (DOE-CSGF)Burroughs Wellcome Fund (Career Award at the Scientific Interface

Excited-State Electronic Structure with Configuration Interaction Singles and Tamm–Dancoff Time-Dependent Density Functional Theory on Graphical Processing Units

Excited-state calculations are implemented in a development version of the GPU-based TeraChem software package using the configuration interaction singles (CIS) and adiabatic linear response Tamm–Dancoff time-dependent density functional theory (TDA-TDDFT) methods. The speedup of the CIS and TDDFT methods using GPU-based electron repulsion integrals and density functional quadrature integration allows full ab initio excited-state calculations on molecules of unprecedented size. CIS/6-31G and TD-BLYP/6-31G benchmark timings are presented for a range of systems, including four generations of oligothiophene dendrimers, photoactive yellow protein (PYP), and the PYP chromophore solvated with 900 quantum mechanical water molecules. The effects of double and single precision integration are discussed, and mixed precision GPU integration is shown to give extremely good numerical accuracy for both CIS and TDDFT excitation energies (excitation energies within 0.0005 eV of extended double precision CPU results)