Use of LEU in the aqueous homogeneous medical isotope production reactor
Energy Technology Data Exchange (ETDEWEB)
Ball, R.M. [Babock & Wilcox, Lynchburg, VA (United States)
1997-08-01
The Medical Isotope Production Reactor (MIPR) is an aqueous solution of uranyl nitrate in water, contained in an aluminum cylinder immersed in a large pool of water which can provide both shielding and a medium for heat exchange. The control rods are inserted at the top through re-entrant thimbles. Provision is made to remove radiolytic gases and recombine emitted hydrogen and oxygen. Small quantities of the solution can be continuously extracted and replaced after passing through selective ion exchange columns, which are used to extract the desired products (fission products), e.g. molybdenum-99. This reactor type is known for its large negative temperature coefficient, the small amount of fuel required for criticality, and the ease of control. Calculation using TWODANT show that a 20% U-235 enriched system, water reflected can be critical with 73 liters of solution.
AQUEOUS HOMOGENEOUS REACTORTECHNICAL PANEL REPORT
Energy Technology Data Exchange (ETDEWEB)
Diamond, D.J.; Bajorek, S.; Bakel, A.; Flanagan, G.; Mubayi, V.; Skarda, R.; Staudenmeier, J.; Taiwo, T.; Tonoike, K.; Tripp, C.; Wei, T.; Yarsky, P.
2010-12-03
Considerable interest has been expressed for developing a stable U.S. production capacity for medical isotopes and particularly for molybdenum- 99 (99Mo). This is motivated by recent re-ductions in production and supply worldwide. Consistent with U.S. nonproliferation objectives, any new production capability should not use highly enriched uranium fuel or targets. Conse-quently, Aqueous Homogeneous Reactors (AHRs) are under consideration for potential 99Mo production using low-enriched uranium. Although the Nuclear Regulatory Commission (NRC) has guidance to facilitate the licensing process for non-power reactors, that guidance is focused on reactors with fixed, solid fuel and hence, not applicable to an AHR. A panel was convened to study the technical issues associated with normal operation and potential transients and accidents of an AHR that might be designed for isotope production. The panel has produced the requisite AHR licensing guidance for three chapters that exist now for non-power reactor licensing: Reac-tor Description, Reactor Coolant Systems, and Accident Analysis. The guidance is in two parts for each chapter: 1) standard format and content a licensee would use and 2) the standard review plan the NRC staff would use. This guidance takes into account the unique features of an AHR such as the fuel being in solution; the fission product barriers being the vessel and attached systems; the production and release of radiolytic and fission product gases and their impact on operations and their control by a gas management system; and the movement of fuel into and out of the reactor vessel.
Energy Technology Data Exchange (ETDEWEB)
Perez, Daniel Milian; Lorenzo, Daniel E. Milian; Garcia, Lorena P. Rodriguez; Llanes, Jesus Salomon; Hernandez, Carlos R. Garcia, E-mail: dperez@instec.cu, E-mail: dmilian@instec.cu, E-mail: lorenapilar@instec.cu, E-mail: cgh@instec.cu [Instituto Superior de Tecnologias y Ciencias Aplicadas (InSTEC), La Habana (Cuba); Lira, Carlos A. Brayner de Oliveira, E-mail: cabol@ufpe.br [Universidade Federal de Pernambuco (UFPE), Recife (Brazil); Rodriguez, Manuel Cadavid, E-mail: mcadavid2001@yahoo.com [Tecnologia Nuclear Medica Spa, TNM (Chile)
2015-07-01
{sup 99m}Tc is the most common radioisotope used in nuclear medicine. It is a very useful radioisotope, which is used in about 30-40 million procedures worldwide every year. Medical diagnostic imaging techniques using {sup 99m}Tc represent approximately 80% of all nuclear medicine procedures. Although {sup 99m}Tc can be produced directly on a cyclotron or other type of particle accelerator, currently is almost exclusively produced from the beta-decay of its 66-h parent {sup 99}Mo. {sup 99}Mo production system in an Aqueous Homogeneous Reactor (AHR) is potentially advantageous because of its low cost, small critical mass, inherent passive safety, and simplified fuel handling, processing and purification characteristics. In this paper, an AHR conceptual design using Low Enriched Uranium (LEU) is studied and optimized for the production of {sup 99}Mo. Aspects related with the neutronic behavior such as optimal reflector thickness, critical height, medical isotopes production and the reactivity feedback introduced in the solution by the volumetric expansion of the fuel solution due to thermal expansion of the fuel solution and the void volume generated by radiolytic gas bubbles were evaluated. Thermal-hydraulics studies were carried out in order to show that sufficient cooling capacity exists to prevent fuel overheating. The neutronic and thermal-hydraulics calculations have been performed with the MCNPX computational code and the version 14 of ANSYS CFX respectively. The neutronic calculations demonstrated that the reactor is able to produce 370 six-day curies of {sup 99}Mo in 5 days operation cycles and the CFD simulation demonstrated that the heat removal systems provide sufficient cooling capacity to prevent fuel overheating, the maximum temperature reached by the fuel (89.29 deg C) was smaller to the allowable temperature limit (90 deg C). (author)
Simulator for SUPO, a Benchmark Aqueous Homogeneous Reactor (AHR)
Energy Technology Data Exchange (ETDEWEB)
Klein, Steven Karl [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Determan, John C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-10-14
A simulator has been developed for SUPO (Super Power) an aqueous homogeneous reactor (AHR) that operated at Los Alamos National Laboratory (LANL) from 1951 to 1974. During that period SUPO accumulated approximately 600,000 kWh of operation. It is considered the benchmark for steady-state operation of an AHR. The SUPO simulator was developed using the process that resulted in a simulator for an accelerator-driven subcritical system, which has been previously reported.
Simulator for SUPO, a Benchmark Aqueous Homogeneous Reactor (AHR)
International Nuclear Information System (INIS)
A simulator has been developed for SUPO (Super Power) an aqueous homogeneous reactor (AHR) that operated at Los Alamos National Laboratory (LANL) from 1951 to 1974. During that period SUPO accumulated approximately 600,000 kWh of operation. It is considered the benchmark for steady-state operation of an AHR. The SUPO simulator was developed using the process that resulted in a simulator for an accelerator-driven subcritical system, which has been previously reported.
Development of fuel management code for aqueous homogeneous reactors
International Nuclear Information System (INIS)
Fuel Management Code for Aqueous Homogeneous Reactors (FMCAHR) is developed based on the Monte Carlo transport method. FMCAHR has the ability of doing resonance treatment, searching for critical control rods height, and calculating the thermal hydraulic parameters, bubble volume fraction and burn-up. The main structure and development process of FMCAHR is introduced in this paper, and the verification shows that the computing results of FMCAHR are precise. (authors)
Final report on the aqueous homogeneous suspension reactor project
International Nuclear Information System (INIS)
The most important results of twenty five years of research and development work on circulating aqueous homogeneous suspensions of fissile material are presented. Experiments in the final phase were carried out with a prototype nuclear reactor (KEMA Suspension Test Reactor, KSTR), fuelled with an aqueous suspension of UO2/ThO2 particles. Summarizing the results of the experimental and post-operational research on the KSTR, it can be stated that the suspension reactor has largely fulfilled the expectations of its designers. No operational problems worth mentioning occurred during an experimental period covering several years. From the standpoint of reactor physics the results can be termed wholly favourable, especially at a high power level. The reactor proved to be inherently safe due to the prompt action of the comparatively high negative coefficient of reactivity. The mechanical behaviour of the parts inspected has also satisfied expectations. The problems encountered have been due exclusively to the presence of a flow stabilizer. This was installed in the period following some time of subcritical operation in order to reduce the reactivity fluctuations. A stabilizer closed on all sides might perhaps have prevented the problems mentioned and the applicability of the principle of the suspension reactor would have been demonstrated still more clearly. 19 refs.; 45 figs.; 7 tabs
International Nuclear Information System (INIS)
Technetium-99m (99mTc), the daughter of Molybdenum-99 (99Mo), is the most commonly used medical radioisotope in the world. It accounts for over twenty-five million medical procedures each year worldwide, comprising about 80% of all radiopharmaceutical procedures. 99Mo is mostly prepared by the fission of uranium-235 targets in a nuclear reactor with a fission yield of about 6.1%. Currently over 95% of the fission product 99Mo is obtained using highly enriched uranium (HEU) targets. Smaller scale producers use low enriched uranium (LEU) targets. Small quantities of 99Mo are also produced by neutron activation through the use of the (n, γ) reaction. The concept of a compact homogeneous aqueous reactor fuelled by a uranium salt solution with off-line separation of radioisotopes of interest (99Mo, 131I) from aliquots of irradiated fuel solution has been cited in a few presentations in the series of International Conference on Isotopes (ICI) held in Vancouver (2000), Cape Town (2003) and Brussels (2005) and recently some corporate interest has also been noticeable. Calculations and some experimental research have shown that the use of aqueous homogeneous reactors (AHRs) could be an efficient technology for fission radioisotope production, having some prospective advantages compared with traditional technology based on the use of solid uranium targets irradiated in research reactors. This review of AHR status and prospects by a team of experts engaged in the field of homogeneous reactors and radioisotope producers yields an objective evaluation of the technological challenges and other relevant implications. The meeting to develop this report facilitated the exchange of information on the 'state of the art' of the technology related to homogeneous aqueous solution nuclear reactors, especially in connection with the production of radioisotopes. This publication presents a summary of discussions of a consultants meeting which is followed by the technical presentations
International Nuclear Information System (INIS)
99mTc is a very useful radioisotope in medical diagnostic procedure. 99mTc is produced from 99Mo decay. Currently, most of 99Mo is produced by irradiating 235U in the nuclear reactor. 99Mo mostly results from the fission reaction of 235U targets with a fission yield about 6.1%. A small additional amount is created from 98Mo neutron activation. Actually 99Mo is also created in the reactor fuel, but usually we do not extract it. The fuel will become spent fuel which is a highly radioactive waste. 99Mo production system in the aqueous homogeneous reactor offers a better method, because all of the 99Mo can be extracted from the fuel solution. Fresh reactor fuel solution consists of uranyl nitrate dissolved in water. There is no separation of target and fuel in an aqueous homogeneous reactor where target and fuel become one liquid solution, and there is no spent fuel generated from this reactor. Simulation of the extraction process is performed while reactor in operation (without reactor shutdown). With an extraction flow rate of 3.6 L/h, after 43 hours of reactor operation the production of 99Mo is relatively constant at about 98.6 curie/hour. (author)
Directory of Open Access Journals (Sweden)
A. Isnaeni
2014-04-01
Full Text Available 99mTc is a very useful radioisotope in medical diagnostic procedure. 99mTc is produced from 99Mo decay. Currently, most of 99Mo is produced by irradiating 235U in the nuclear reactor. 99Mo mostly results from the fission reaction of 235U targets with a fission yield about 6.1%. A small additional amount is created from 98Mo neutron activation. Actually 99Mo is also created in the reactor fuel, but usually we do not extract it. The fuel will become spent fuel which is a highly radioactive waste. 99Mo production system in the aqueous homogeneous reactor offers a better method, because all of the 99Mo can be extracted from the fuel solution. Fresh reactor fuel solution consists of uranyl nitrate dissolved in water. There is no separation of target and fuel in an aqueous homogeneous reactor where target and fuel become one liquid solution, and there is no spent fuel generated from this reactor. Simulation of the extraction process is performed while reactor in operation (without reactor shutdown. With an extraction flow rate of 3.6 L/h, after 43 hours of reactor operation the production of 99Mo is relatively constant at about 98.6 curie/hour
Energy Technology Data Exchange (ETDEWEB)
Cooling, C.M., E-mail: c.cooling10@imperial.ac.uk [Imperial College of Science, Technology and Medicine (United Kingdom); Williams, M.M.R. [Imperial College of Science, Technology and Medicine (United Kingdom); Nygaard, E.T. [Babcock and Wilcox Technical Services Group (TSG) (United States); Eaton, M.D. [Imperial College of Science, Technology and Medicine (United Kingdom)
2013-09-15
Highlights: • A point kinetics model for the Medical Isotope Production Reactor is formulated. • Reactivity insertions are simulated using this model. • Polynomial chaos is used to simulate uncertainty in reactor parameters. • The computational efficiency of polynomial chaos is compared to that of Monte Carlo. -- Abstract: This paper models a conceptual Medical Isotope Production Reactor (MIPR) using a point kinetics model which is used to explore power excursions in the event of a reactivity insertion. The effect of uncertainty of key parameters is modelled using intrusive polynomial chaos. It is found that the system is stable against reactivity insertions and power excursions are all bounded and tend towards a new equilibrium state due to the negative feedbacks inherent in Aqueous Homogeneous Reactors (AHRs). The Polynomial Chaos Expansion (PCE) method is found to be much more computationally efficient than that of Monte Carlo simulation in this application.
REMOVAL OF REMAZOL ROSSO RB DYE FROM AQUEOUS EFFLUENTS BY HOMOGENOUS FENTON OXIDATION PROCESSES
Carmen Zaharia; Victoria Fedorcea; Adrian Beda; Victor Amarandei; Augustin Muresan
2014-01-01
The paper presents some data from our laboratory-setup experiments of homogenous oxidative processes with hydrogen peroxide (i.e. advanced Fenton oxidation processes) applied for Remazol Rosso RB dye-containing aqueous systems, especially textile effluents. Therefore, some different operating parameters (including pH, concentration of dye, H2O2 and ferrous ions, oxidation time, temperature, stirring regime, among its) were tested for determination of the best performance in effluent decolorat...
Directory of Open Access Journals (Sweden)
Jun Kobayashi
2015-01-01
Full Text Available We propose a robust method to distinguish isolated single gold nanoparticles (AuNP monomers and their dimers under Brownian motion, a key for ultrasensitive homogeneous bioassays, including AuNP sandwich assays. To detect dimers and distinguish them from a larger number of monomers in aqueous solution, single-particle polarization microscopy was performed. For the accurate detection of individual particles, the optical anisotropy and rotational diffusion time are measured because a dimer is much more anisotropic than the nearly spherical monomer and the rotational diffusion time of a dimer is four times that of a monomer. By employing an autocorrelation analysis, we defined a measure of distinguishing that simultaneously enables high detection probability and low error probability. The detection platform offers homogeneous DNA hybridization assays and immunoassays at the subpicomolar level.
REMOVAL OF REMAZOL ROSSO RB DYE FROM AQUEOUS EFFLUENTS BY HOMOGENOUS FENTON OXIDATION PROCESSES
Directory of Open Access Journals (Sweden)
Carmen Zaharia
2014-06-01
Full Text Available The paper presents some data from our laboratory-setup experiments of homogenous oxidative processes with hydrogen peroxide (i.e. advanced Fenton oxidation processes applied for Remazol Rosso RB dye-containing aqueous systems, especially textile effluents. Therefore, some different operating parameters (including pH, concentration of dye, H2O2 and ferrous ions, oxidation time, temperature, stirring regime, among its were tested for determination of the best performance in effluent decoloration and dye removal, meaning the optimal values of each studied parameters for highest decoloration or dye removal.
Zhang, Hairong; Guo, Haijun; Wang, Bo; Shi, Silan; Xiong, Lian; Chen, Xinde
2016-01-20
In this work, bacterial cellulose (BC) was activated by ethylenediamine (EDA) and then dissolved in lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) aqueous solutions. The resulting transparent solution was cast on a glass plate to prepare regenerated BC. Then cationic BC was prepared homogeneously by the reaction between regenerated BC and 3-chloro-2-hydroxypropyl-trimethyl ammonium chloride (CHPTAC) in a NaOH/urea aqueous solution. Structure and properties of the BC and its products were characterized by different techniques such as X-ray diffraction (XRD), Fourier transform spectroscopy (FT-IR), scanning electron microscopy (SEM) and thermo-gravimetric analysis (TGA). The results showed that there was no significant difference between the structures of BC, activated BC and regenerated BC. The effects of different temperature and molar ratio of CHPTAC to anhydroglucose unit (AGU) on the degree of substitution (DS) value were examined. The DS values of cationic BC ranged between 0.21 and 0.51. PMID:26572343
Institute of Scientific and Technical Information of China (English)
Soheil Sayyahi; Jafar Saghanezhad
2011-01-01
In this letter, a mild and efficient procedure for synthesis of phenacyl derivatives under homogenous catalysis in the presence of tetrabutylammonium bromide in aqueous media is described. The nucleophilic substitution reactions were performed under ecofriendly conditions and gave the corresponding products in high yields and short reaction times.
Homogeneous liquid-liquid extraction of uranium(VI) from acetate aqueous solution
International Nuclear Information System (INIS)
A selective and very effective concentration method for uranium(VI) was developed by the homogeneous liquid-liquid extraction method based on the ion-pair phase separation of perfluorooctanoate ion (PFOA-) with tetrabutylammonium ion (TBA+). Under the experimental conditions ([PFOA-]T=6.67x10-3 M, [TBA+]T=5.0x10-2 M, [acetate]T=0.17 M, pH 4.0), the extraction % of uranium(VI) was 96%, and the maximum concentration factor was approximately 330-fold (i.e., 90 μl of the sedimented phase was produced from 30 ml of the aqueous phase). The extracted species was estimated by the normal liquid-liquid extraction method in a water/ethyl acetate system to be UO2(CH3COO)-3·TBA+. The proposed homogeneous liquid-liquid extraction method was applied as a preconcentration method for the spectrophotometric determination of uranium(VI) with arsenazo III. The calibration graph was linear over the range 3.3x10-8-2.7x10-6 M. The relative standard deviation for the central value of the calibration graph was 1.4% (10 determinations), and the detection limit (S/N=3) was 6.0x10-10 M. When the proposed method was applied to the separation and determination of uranium(VI) added to sea water, the results were satisfactory. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)
A novel approach to the production of medical radioisotopes: the homogeneous SLOWPOKE reactor
Energy Technology Data Exchange (ETDEWEB)
Bonin, H.W., E-mail: bonin-h@rmc.ca [Royal Military College of Canada, Kingston, Ontario (Canada); Hilborn, J.W. [retired, Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Carlin, G.E. [Ontario Power Generation, Toronto, Ontario (Canada); Gagnon, R.; Busatta, P. [Royal Canadian Navy, Ottawa, Ontario (Canada)
2015-03-15
In 2009, the unexpected 15-month outage of the Canadian NRU nuclear reactor resulted in a sudden 30% world shortage, with higher shortages experienced in North America than in Europe. Commercial radioisotope production is from just eight nuclear reactors, most being aging systems near the end of their service life. This paper proposes a more efficient production and distribution model. Tc-99m unit doses would be distributed to regional hospitals from ten integrated 'industrial radiopharmacies', located at existing licensed nuclear reactor sites in North America. At each site, one or more 20 kW Homogeneous SLOWPOKE nuclear reactors would deliver 15 litres of irradiated aqueous uranyl sulfate fuel solution daily to industrial-scale hot cells, for extraction of Mo-99; and the low-enriched uranium would be recycled. Purified Mo-99 would be incorporated in large Mo-99/Tc-99m generators for extraction of Tc-99m five days a week; and each automated hot-cell facility would be designed to load up to 7,000 Tc-99m syringes daily for road delivery to all of the nuclear medicine hospitals within a 3-hour range. At the current price of $20 per unit dose, the annual gross income from 10 sites would be approximately $360 million. The Homogeneous SLOWPOKE reactor evolved from the inherently safe SLOWPOKE-2 research reactor, with a double goal: replacing the heterogeneous SLOWPOKE-2 reactors at the end-of-core life, enabling them to continue their primary missions of research and education, together with full time commercial radioisotope production. The Homogeneous SLOWPOKE reactor was modelled using both deterministic and probabilistic reactor simulation codes. The homogeneous fuel mixture is a dilute aqueous solution of low-enriched uranyl sulfate containing approximately 1 kg of U-235. The reactor is controlled by mechanical absorber rods in the beryllium reflector. Safety analysis was carried out for both normal operation and transient conditions. The most severe
International Nuclear Information System (INIS)
99mTc is a very useful radioisotope, which is used in nearly 80% of all nuclear medicine procedures. 99mTc is produced from 99Mo decay. Since 2007 the medical community has been plagued by 99Mo shortages due to aging reactors, such as the National Research Universal reactor in Canada and the High Flux Reactor in Petten, The Netherlands. At present, most of the world's supply of 99Mo for medical isotope production involves the neutron fission of 235U in multipurpose research reactors. 99Mo mostly results from the fission reaction of 235U targets with a fission yield about 6.1%. After irradiation in the reactor, the target is digested in acid or alkaline solutions and 99Mo is recovered through a series of extraction (separation) and purification steps. 99Mo production system in an Aqueous Homogeneous Reactor (AHR) offers a better method, because all of the 99Mo can be extracted from the fuel solution. Over 30 AHRs has been built and operated around the world with 149 years of combined experience. In this paper, an AHR conceptual design using LEU (Low Enriched Uranium) is optimized to meet the South American demand for 99Mo for the coming years. Aspect related with the neutronic behavior such as optimal reflector thickness, critical height, medical isotope production and others are evaluated. The neutronic calculations have been performed with the well-known MCNPX computational code. A benchmarking experiments performed at the Russian Research Center 'Kurchatov Institute' in order to validate that the developed models of AHRs with MCNPX code and the available library in XSDIR, ENDF/B VI.2, are adequate for studies of aqueous fuel solutions. (Author)
Conceptual design of a new homogeneous reactor for medical radioisotope Mo-99/Tc-99m production
Energy Technology Data Exchange (ETDEWEB)
Liem, Peng Hong [Nippon Advanced Information Service (NAIS Co., Inc.) Scientific Computational Division, 416 Muramatsu, Tokaimura, Ibaraki (Japan); Tran, Hoai Nam [Chalmers University of Technology, Dept. of Applied Physics, Div. of Nuclear Engineering, SE-412 96 Gothenburg (Sweden); Sembiring, Tagor Malem [National Nuclear Energy Agency (BATAN), Center for Reactor Technology and Nuclear Safety, Kawasan Puspiptek, Serpong, Tangerang Selatan, Banten (Indonesia); Arbie, Bakri [PT MOTAB Technology, Kedoya Elok Plaza Blok DA 12, Jl. Panjang, Kebun Jeruk, Jakarta Barat (Indonesia)
2014-09-30
To partly solve the global and regional shortages of Mo-99 supply, a conceptual design of a nitrate-fuel-solution based homogeneous reactor dedicated for Mo-99/Tc-99m medical radioisotope production is proposed. The modified LEU Cintichem process for Mo-99 extraction which has been licensed and demonstrated commercially for decades by BATAN is taken into account as a key design consideration. The design characteristics and main parameters are identified and the advantageous aspects are shown by comparing with the BATAN's existing Mo-99 supply chain which uses a heterogeneous reactor (RSG GAS multipurpose reactor)
Magnetic separation of Dy(III) ions from homogeneous aqueous solutions
International Nuclear Information System (INIS)
The possibility to enrich paramagnetic dysprosium(III) ions in a magnetic field gradient is proved by means of interferometry, which may open the route for a magnetic separation of rare earth ions from aqueous solutions. The separation dynamics are studied for three different concentrations of DyCl3 and compared with those found recently in a sulphate solution of the 3d ion Mn(II). In view of the similar-sized hydration spheres for Dy(III) and Mn(II), the slower separation dynamics in DyCl3 is attributed to both a higher densification coefficient and the strong impact of Brownian motion due to the absence of ion-pair clusters
Tan, Chongxiao; Gajovic-Eichelmann, Nenad; Polzius, Rainer; Hildebrandt, Niko; Bier, Frank F
2010-11-01
The detection of the major active component of cannabis, Δ9-tetrahydrocannabinol (THC), becomes increasingly relevant due to its widespread abuse. For control purposes, some easy-to-use, sensitive and inexpensive test methods are needed. We have developed a fluorescence immunoassay utilising THC-fluorescein conjugate as tracer. Fluorescence spectroscopy of the conjugate revealed an unusual property: The relatively weak fluorescence of a dilute tracer solution was increased by a factor of up to 5 after binding of a THC-specific antibody. Fluorescence lifetime measurements in aqueous solutions suggested two different tracer conformations both associated with quenching of fluorescein fluorescence by the intramolecular THC moiety. After antibody binding, the tracer enters a third conformation in which fluorescence quenching of fluorescein is completely suppressed. Utilising this property, we established a homogeneous competitive immunoassay (homogeneous increasing fluorescence immunoassay) with low detection limits. The test requires only two reagents, the new tracer molecule and an anti-THC antibody. A single test takes only 8 min. The dynamic detection range for THC is 0.5 to 20 ng/mL in buffer, with a limit of detection (LOD) of 0.5 ng/mL. The test also works in diluted saliva samples (1:10 dilution with buffer) with an LOD of 2 ng/mL and a dynamic range of 2-50 ng/mL. PMID:20740278
Peng, Na; Ai, Ziye; Fang, Zehong; Wang, Yanfeng; Xia, Zhiping; Zhong, Zibiao; Fan, Xiaoli; Ye, Qifa
2016-10-01
Water-soluble quaternized chitins (QCs) were homogeneously synthesized by reacting chitin with (3-chloro-2-hydroxypropyl) trimethylammonium chloride (CHPTAC) in 8wt% NaOH/4wt% urea aqueous solutions. The chemical structure and solution properties of the quaternized chitins were characterized by (1)H NMR, FT-IR, elemental analysis, dynamic light scattering (DLS) and zeta potential measurements. The results demonstrated that the water-soluble QCs, with a degree of substitution (DS) values of 0.27-0.54, could be obtained by varying the concentration of chitin, the molar ratio of CHPTAC to chitin unit, and the reaction time at room temperature (25°C). Two QCs (DS=0.36 and 0.54) were selected and studied as gene carriers. Agarose gel retardation assay revealed that both QCs could condense DNA efficiently when N/P ratio>3. The results of particle size and zeta potential indicated that both QCs had a good ability of condensing plasmid DNA into compact nanoparticles with the size of 100-200nm and zeta potential of +18 to +36mV. Compared to polyethylenimine (PEI, 25kDa), the QCs exhibited outstanding low cytotoxicity. Transfection efficiencies of the QCs/DNA complexes were measured using pGL-3 encoding luciferase as the foreign DNA, and the QCs/DNA complexes showed effective transfection efficiencies in 293T cells. These results revealed that the QCs prepared in NaOH/urea aqueous solutions could be used as promising non-viral gene carriers owing to their excellent characteristics. PMID:27312628
Liu, Lingzhi; Dong, Xiaohu; Xiao, Yan; Lian, Wenlong; Liu, Zhihong
2011-05-21
In the present work, a two-photon excited fluorescent chemosensor for Cu(2+) was prepared. The probe was constructed on the basis of internal charge transfer (ICT) principle with macrocyclic dioxotetraamine as the Cu(2+) receptor. The good water-solubility of the molecule enabled recognition and assay of Cu(2+) ions in biological media. The photophysical properties of the chemosensor were investigated in detail, exhibiting favorable fluorescence quantum yield and moderate two-photon absorption cross-section. The studies on binding thermodynamics demonstrated the formation of 1 : 1 complex between the chemosensor and Cu(2+) and an association constant of ca. 1.04 × 10(5) M(-1). Due to the rational design of the molecular structure, the sensor was highly specific to Cu(2+), which ensured high selectivity in Cu(2+) determination. Upon Cu(2+) binding, the intramolecular charge-transfer extent within the chromophore was weakened resulting in a remarkable quenching of fluorescence, based on which quantitative determination of Cu(2+) was performed. Good linearity was obtained between the fluorescence quenching value and Cu(2+) concentration ranging from 0.04 to 2.0 μM in aqueous solution. Benefiting from the merits of two-photon excitation, the chemosensor was free of interference from background luminescence in serum. A homogeneous quantitative determination of Cu(2+) was achieved in the serum medium with a linear range of 0.04 to 2.0 μM. Considering the structural flexibility of the sensor, this work also opens up the possibility to construct other two-photon excited chemosensors for direct homogeneous assay of various molecules/ions in complicated biological sample matrices. PMID:21416097
Thermal-Hydraulics Study of a 75 kWth Aqueous Homogeneous Reactor for 99Mo Production
Directory of Open Access Journals (Sweden)
Daniel Milian Pérez
2015-01-01
Full Text Available Tc99m is a very useful radioisotope, which is used in nearly 80% of all nuclear medicine procedures. Tc99m is produced from 99Mo decay. A potentially advantageous alternative to meeting current and future demand for 99Mo is the use of Aqueous Homogeneous Reactors (AHR. In this paper, a thermal-hydraulics study of the core of a 75 kWth AHR conceptual design based on the ARGUS reactor for 99Mo production is presented. As the ARGUS heat removal systems were designed for working at 20 kWth, the main objective of the thermal-hydraulics study was evaluating the heat removal systems in order to show that sufficient cooling capacity exists to prevent fuel solution overheating. The numerical simulations of an AHR model were carried out using the Computational Fluid Dynamic (CFD code ANSYS CFX 14. Evaluation shows that the ARGUS heat removal systems working at 75 kWth are not able to provide sufficient cooling capacity to prevent fuel solution overheating. To solve this problem, the number of coiled cooling pipes inside the core was increased from one to five. The results of the CFD simulations with this modification in the design show that acceptable temperature distributions can be obtained.
International Nuclear Information System (INIS)
Dialkyl- and diarylammonium ions are able to form complexes with α-cyclodextrin and cucurbit[6]uril. These amines are able to complex two guest molecules simultaneously resulting in the formation of homogeneous or heterogeneous 1:2 (ratio of dialkylammonium to ligand) complexes. The stability constants and reaction enthalpies for the formation of 1:1 complexes have been measured using potentiometric and calorimetric titrations. Differences between the values obtained by these methods can be attributed to solvent composition. Only for the 1:2 complex formation with cucurbit[6]uril, the ligands influenced each other. The polar carbonyl groups at each portal of the cucurbit[6]urils interacted simultaneously with the protonated amino group resulting in an electrostatic repulsion between both molecules. No further interactions between two complexed molecules of α-cyclodextrin or cucurbit[6]uril and α-cyclodextrin were observed. The absence of polar groups in the case of α-cyclodextrin led to unaffected formation of homogeneous and even heterogeneous 1:2 complexes.
Chadwick, John C; Freixa, Zoraida; van Leeuwen, Piet W N M
2011-01-01
This first book to illuminate this important aspect of chemical synthesis improves the lifetime of catalysts, thus reducing material and saving energy, costs and waste.The international panel of expert authors describes the studies that have been conducted concerning the way homogeneous catalysts decompose, and the differences between homogeneous and heterogeneous catalysts. The result is a ready reference for organic, catalytic, polymer and complex chemists, as well as those working in industry and with/on organometallics.
Energy Technology Data Exchange (ETDEWEB)
Sanchez, R.; Ragusa, J.; Santandrea, S. [Commissariat a l' Energie Atomique, Direction de l' Energie Nucleaire, Service d' Etudes de Reacteurs et de Modelisation Avancee, CEA de Saclay, DM2S/SERMA 91 191 Gif-sur-Yvette cedex (France)]. e-mail: richard.sanchez@cea.fr
2004-07-01
The problem of the determination of a homogeneous reflector that preserves a set of prescribed albedo is considered. Duality is used for a direct estimation of the derivatives needed in the iterative calculation of the optimal homogeneous cross sections. The calculation is based on the preservation of collapsed multigroup albedo obtained from detailed reference calculations and depends on the low-order operator used for core calculations. In this work we analyze diffusion and transport as low-order operators and argue that the P{sub 0} transfers are the best choice for the unknown cross sections to be adjusted. Numerical results illustrate the new approach for SP{sub N} core calculations. (Author)
Lai, Chien-Han; Wu, Yu-Te
2016-03-01
This study surveyed the characteristics of the indicator for the synchrony of brain activities, regional homogeneity (ReHo), in patients who were diagnosed with major depressive disorder (MDD) without co-morbidities. Forty-four patients with MDD and twenty-seven normal controls were enrolled in our study. The ReHo outputs of patients and controls were compared by a nonparametric permutation-based method with global brain volume, age, and gender as covariates. In addition, the correlations between the clinical variables (such as depression severity, anxiety severity, illness duration) and ReHo values were also estimated in each group and across both groups. The patients with MDD had lower ReHo values than the controls for the cognitive division of right anterior cingulate cortex and the left inferior parietal lobule. In contrast, the patients had higher values of ReHo than controls for the right inferior temporal lobe and the right cerebellum. Additionally, the ReHo values were negatively correlated with the depression severity and with illness duration in the right anterior cingulate cortex. MDD patients had significant alterations in the ReHo of the parieto-cingulate and temporo-cerebellum regions with opposite trends. PMID:25904155
Calviño-Louzao, E.; Hervella, L. M.; Seoane-Bascoy, J.; Vázquez-Lorenzo, R.
2013-01-01
Left-invariant Cotton solitons on homogeneous manifolds are determined. Moreover, algebraic Cotton solitons are studied providing examples of non-invariant Cotton solitons, both in the Riemannian and Lorentzian homogeneous settings.
Homogeneity of Inorganic Glasses
DEFF Research Database (Denmark)
Jensen, Martin; Zhang, L.; Keding, Ralf;
2011-01-01
Homogeneity of glasses is a key factor determining their physical and chemical properties and overall quality. However, quantification of the homogeneity of a variety of glasses is still a challenge for glass scientists and technologists. Here, we show a simple approach by which the homogeneity o...
Passive safety of the Medical Isotope Production Reactor (MIPR)
International Nuclear Information System (INIS)
The Medical Isotope Production Reactor (MIPR) is an aqueous homogeneous reactor designed with the minimum possible waste heat and waste radioactive products, lowest uranium consumption, and enhanced passive safety to produce medical isotopes that are based on short-lived fission products. A major product of the reactor is 99Mo, which decays to a daughter isotope, 99Tc, which can be fixed chemically to pharmaceuticals. Technetium-99 is widely used by the medical community for diagnostic purposes arising form the short half-life and desirable gamma energy of the decay. The only approved method of obtaining 99Mo for use in humans is from a fission product using chemical separation means
Maartens, Roy
2011-12-28
The standard model of cosmology is based on the existence of homogeneous surfaces as the background arena for structure formation. Homogeneity underpins both general relativistic and modified gravity models and is central to the way in which we interpret observations of the cosmic microwave background (CMB) and the galaxy distribution. However, homogeneity cannot be directly observed in the galaxy distribution or CMB, even with perfect observations, since we observe on the past light cone and not on spatial surfaces. We can directly observe and test for isotropy, but to link this to homogeneity we need to assume the Copernican principle (CP). First, we discuss the link between isotropic observations on the past light cone and isotropic space-time geometry: what observations do we need to be isotropic in order to deduce space-time isotropy? Second, we discuss what we can say with the Copernican assumption. The most powerful result is based on the CMB: the vanishing of the dipole, quadrupole and octupole of the CMB is sufficient to impose homogeneity. Real observations lead to near-isotropy on large scales--does this lead to near-homogeneity? There are important partial results, and we discuss why this remains a difficult open question. Thus, we are currently unable to prove homogeneity of the Universe on large scales, even with the CP. However, we can use observations of the cosmic microwave background, galaxies and clusters to test homogeneity itself. PMID:22084298
Benchmarking monthly homogenization algorithms
Directory of Open Access Journals (Sweden)
V. K. C. Venema
2011-08-01
Full Text Available The COST (European Cooperation in Science and Technology Action ES0601: Advances in homogenization methods of climate series: an integrated approach (HOME has executed a blind intercomparison and validation study for monthly homogenization algorithms. Time series of monthly temperature and precipitation were evaluated because of their importance for climate studies and because they represent two important types of statistics (additive and multiplicative. The algorithms were validated against a realistic benchmark dataset. The benchmark contains real inhomogeneous data as well as simulated data with inserted inhomogeneities. Random break-type inhomogeneities were added to the simulated datasets modeled as a Poisson process with normally distributed breakpoint sizes. To approximate real world conditions, breaks were introduced that occur simultaneously in multiple station series within a simulated network of station data. The simulated time series also contained outliers, missing data periods and local station trends. Further, a stochastic nonlinear global (network-wide trend was added.
Participants provided 25 separate homogenized contributions as part of the blind study as well as 22 additional solutions submitted after the details of the imposed inhomogeneities were revealed. These homogenized datasets were assessed by a number of performance metrics including (i the centered root mean square error relative to the true homogeneous value at various averaging scales, (ii the error in linear trend estimates and (iii traditional contingency skill scores. The metrics were computed both using the individual station series as well as the network average regional series. The performance of the contributions depends significantly on the error metric considered. Contingency scores by themselves are not very informative. Although relative homogenization algorithms typically improve the homogeneity of temperature data, only the best ones improve
Homogenization approach in engineering
International Nuclear Information System (INIS)
Homogenization is an approach which studies the macrobehavior of a medium by its microproperties. Problems with a microstructure play an essential role in such fields as mechanics, chemistry, physics, and reactor engineering. Attention is concentrated on a simple specific model problem to illustrate results and problems typical of the homogenization approach. Only the diffusion problem is treated here, but some statements are made about the elasticity of composite materials. The differential equation is solved for linear cases with and without boundaries and for the nonlinear case. 3 figures, 1 table
Dynamics of homogeneous nucleation
DEFF Research Database (Denmark)
Toxværd, Søren
2015-01-01
clusters fluctuates, but the mean temperature remains below the temperature in the supersaturated gas until they reach the critical nucleation size. The critical nuclei have, however, a temperature equal to the supersaturated gas. The kinetics of homogeneous nucleation is not only caused by a grow or......The classical nucleation theory for homogeneous nucleation is formulated as a theory for a density fluctuation in a supersaturated gas at a given temperature. But molecular dynamics simulations reveal that it is small cold clusters which initiates the nucleation. The temperature in the nucleating...
Tignanelli, H. L.; Vazquez, R. A.; Mostaccio, C.; Gordillo, S.; Plastino, A.
1990-11-01
RESUMEN. Presentamos una metodologia de analisis de la homogeneidad a partir de la Teoria de la Informaci6n, aplicable a muestras de datos observacionales. ABSTRACT:Standard concepts that underlie Information Theory are employed in order design a methodology that enables one to analyze the homogeneity of a given data sample. Key : DATA ANALYSIS
Strictly homogeneous laterally complete modules
Chilin, V. I.; Karimov, J. A.
2016-03-01
Let A be a laterally complete commutative regular algebra and X be a laterally complete A-module. In this paper we introduce a notion of homogeneous and strictly homogeneous A-modules. It is proved that any homogeneous A-module is strictly homogeneous A-module, if the Boolean algebra of all idempotents in A is multi-σ-finite.
Synthesis of silica nanosphere from homogeneous and heterogeneous systems
Indian Academy of Sciences (India)
N Venkatathri
2007-12-01
Silica nanosphere was synthesized using homogeneous and heterogeneous systems, respectively. In homogeneous system, silica spheres were synthesized without cetyltrimethylammonium bromide (CTABr), which gave bimodal particle size and lower yield (77%). To improve the yield, CTABr was added and found that the yield was very high (100%). The particle was in nm range, but the particle sizes are bimodal. To avoid it, reaction in heterogeneous system using CTABr was carried out. Nanosized silica sphere with uniform size (yield, 94%) was observed. Homogeneous system contains a mixture of ethanol, water, aqueous ammonia and tetraethylorthosilicate (TEOS). In the case of heterogeneous system, only ethanol was absent.
Homogenous finitary symmetric groups
Directory of Open Access Journals (Sweden)
Otto. H. Kegel
2015-03-01
Full Text Available We characterize strictly diagonal type of embeddings of finitary symmetric groups in terms of cardinality and the characteristic. Namely, we prove the following. Let kappa be an infinite cardinal. If G=underseti=1stackrelinftybigcupG i , where G i =FSym(kappan i , (H=underseti=1stackrelinftybigcupH i , where H i =Alt(kappan i , is a group of strictly diagonal type and xi=(p 1 ,p 2 ,ldots is an infinite sequence of primes, then G is isomorphic to the homogenous finitary symmetric group FSym(kappa(xi (H is isomorphic to the homogenous alternating group Alt(kappa(xi , where n 0 =1,n i =p 1 p 2 ldotsp i .
Homogeneous group, research, institution
Directory of Open Access Journals (Sweden)
Francesca Natascia Vasta
2014-09-01
Full Text Available The work outlines the complex connection among empiric research, therapeutic programs and host institution. It is considered the current research state in Italy. Italian research field is analyzed and critic data are outlined: lack of results regarding both the therapeutic processes and the effectiveness of eating disorders group analytic treatment. The work investigates on an eating disorders homogeneous group, led into an eating disorder outpatient service. First we present the methodological steps the research is based on including the strong connection among theory and clinical tools. Secondly clinical tools are described and the results commented. Finally, our results suggest the necessity of validating some more specifical hypothesis: verifying the relationship between clinical improvement (sense of exclusion and painful emotions reduction and specific group therapeutic processes; verifying the relationship between depressive feelings, relapses and transition trough a more differentiated groupal field.Keywords: Homogeneous group; Eating disorders; Institutional field; Therapeutic outcome
Homogen Mur - et udviklingsprojekt
DEFF Research Database (Denmark)
Dahl, Torben; Beim, Anne; Sørensen, Peter; Nørbak, Charlotte; Nicolaisen, Ole
1997-01-01
Mølletorvet i Slagelse er det første byggeri i Danmark, hvor ydervæggen er udført af homogene bærende og isolerende teglblokke. Byggeriet viser en række af de muligheder, der både med hensyn til konstruktioner, energiforhold og arkitektur ligger i anvendelsen af homogent blokmurværk.......Mølletorvet i Slagelse er det første byggeri i Danmark, hvor ydervæggen er udført af homogene bærende og isolerende teglblokke. Byggeriet viser en række af de muligheder, der både med hensyn til konstruktioner, energiforhold og arkitektur ligger i anvendelsen af homogent blokmurværk....
Blau, Matthias; O'Loughlin, Martin
2002-01-01
Motivated by the search for potentially exactly solvable time-dependent string backgrounds, we determine all homogeneous plane wave (HPW) metrics in any dimension and find one family of HPWs with geodesically complete metrics and another with metrics containing null singularities. The former generalises both the Cahen-Wallach (constant $A_{ij}$) metrics to time-dependent HPWs, $A_{ij}(t)$, and the Ozsvath-Sch\\"ucking anti-Mach metric to arbitrary dimensions. The latter is a generalisation of ...
Homogenization of dislocation dynamics
International Nuclear Information System (INIS)
In this paper we consider the dynamics of dislocations with the same Burgers vector, contained in the same glide plane, and moving in a material with periodic obstacles. We study two cases: i) the particular case of parallel straight dislocations and ii) the general case of curved dislocations. In each case, we perform rigorously the homogenization of the dynamics and predict the corresponding effective macroscopic elasto-visco-plastic flow rule.
Homogenization of dislocation dynamics
Energy Technology Data Exchange (ETDEWEB)
El Hajj, Ahmad; Ibrahim, Hassan; Monneau, Regis, E-mail: elhajj@cermics.enpc.fr, E-mail: ibrahim@cermics.enpc.fr, E-mail: monneau@cermics.enpc.fr [CERMICS, ENPC, 6 and 8 avenue Blaise Pascal, Cite Descartes, Champs sur Marne, 77455 Marne-la-Valle Cedex 2 (France)
2009-07-15
In this paper we consider the dynamics of dislocations with the same Burgers vector, contained in the same glide plane, and moving in a material with periodic obstacles. We study two cases: i) the particular case of parallel straight dislocations and ii) the general case of curved dislocations. In each case, we perform rigorously the homogenization of the dynamics and predict the corresponding effective macroscopic elasto-visco-plastic flow rule.
Figueroa-O'Farrill, José
2015-01-01
Motivated by the search for new gravity duals to M2 branes with $N>4$ supersymmetry --- equivalently, M-theory backgrounds with Killing superalgebra $\\mathfrak{osp}(N|4)$ for $N>4$ --- we classify (except for a small gap) homogeneous M-theory backgrounds with symmetry Lie algebra $\\mathfrak{so}(n) \\oplus \\mathfrak{so}(3,2)$ for $n=5,6,7$. We find that there are no new backgrounds with $n=6,7$ but we do find a number of new (to us) backgrounds with $n=5$. All backgrounds are metrically products of the form $\\operatorname{AdS}_4 \\times P^7$, with $P$ riemannian and homogeneous under the action of $\\operatorname{SO}(5)$, or $S^4 \\times Q^7$ with $Q$ lorentzian and homogeneous under the action of $\\operatorname{SO}(3,2)$. At least one of the new backgrounds is supersymmetric (albeit with only $N=2$) and we show that it can be constructed from a supersymmetric Freund--Rubin background via a Wick rotation. Two of the new backgrounds have only been approximated numerically.
Deng, Shaoqiang
2012-01-01
"Homogeneous Finsler Spaces" is the first book to emphasize the relationship between Lie groups and Finsler geometry, and the first to show the validity in using Lie theory for the study of Finsler geometry problems. This book contains a series of new results obtained by the author and collaborators during the last decade. The topic of Finsler geometry has developed rapidly in recent years. One of the main reasons for its surge in development is its use in many scientific fields, such as general relativity, mathematical biology, and phycology (study of algae). This monograph introduc
Energy Technology Data Exchange (ETDEWEB)
Blau, Matthias E-mail: mblau@ictp.trieste.it; O' Loughlin, Martin E-mail: loughlin@sissa.it
2003-03-24
Motivated by the search for potentially exactly solvable time-dependent string backgrounds, we determine all homogeneous plane wave (HPW) metrics in any dimension and find one family of HPWs with geodesically complete metrics and another with metrics containing null singularities. The former generalises both the Cahen-Wallach (constant A{sub ij}) metrics to time-dependent HPWs, A{sub ij}(x{sup +}), and the Ozsvath-Schuecking anti-Mach metric to arbitrary dimensions. The latter is a generalisation of the known homogeneous metrics with A{sub ij}{approx}1/(x{sup +}){sup 2} to a more complicated time-dependence. We display these metrics in various coordinate systems, show how to embed them into string theory, and determine the isometry algebra of a general HPW and the associated conserved charges. We review the Lewis-Riesenfeld theory of invariants of time-dependent harmonic oscillators and show how it can be deduced from the geometry of plane waves. We advocate the use of the invariant associated with the extra (timelike) isometry of HPWs for lightcone quantisation, and illustrate the procedure in some examples.
International Nuclear Information System (INIS)
Motivated by the search for potentially exactly solvable time-dependent string backgrounds, we determine all homogeneous plane wave (HPW) metrics in any dimension and find one family of HPWs with geodesically complete metrics and another with metrics containing null singularities. The former generalises both the Cahen-Wallach (constant Aij) metrics to time-dependent HPWs, Aij(x+), and the Ozsvath-Schuecking anti-Mach metric to arbitrary dimensions. The latter is a generalisation of the known homogeneous metrics with Aij∼1/(x+)2 to a more complicated time-dependence. We display these metrics in various coordinate systems, show how to embed them into string theory, and determine the isometry algebra of a general HPW and the associated conserved charges. We review the Lewis-Riesenfeld theory of invariants of time-dependent harmonic oscillators and show how it can be deduced from the geometry of plane waves. We advocate the use of the invariant associated with the extra (timelike) isometry of HPWs for lightcone quantisation, and illustrate the procedure in some examples
Blau, Matthias; Blau, Matthias; Loughlin, Martin O'
2003-01-01
Motivated by the search for potentially exactly solvable time-dependent string backgrounds, we determine all homogeneous plane wave (HPW) metrics in any dimension and find one family of HPWs with geodesically complete metrics and another with metrics with null singularities. The former generalises both the Cahen-Wallach (constant $A_{ij}$) metrics to time-dependent HPWs, $A_{ij}(t)$, and the Ozsvath-Sch\\"ucking anti-Mach metric to arbitrary dimensions. The latter is a generalisation of the known homogeneous metrics with $A_{ij}\\sim 1/t^2$ to a more complicated time-dependence. We display these metrics in various coordinate systems, show how to embed them into string theory, and determine the isometry algebra of a general HPW and the associated conserved charges. We review the Lewis-Riesenfeld theory of invariants of time-dependent harmonic oscillators and show how it can be deduced from the geometry of plane waves. We advocate the use of the invariant associated with the extra (timelike) isometry of HPWs for ...
BWXT Services medical isotope production system status
International Nuclear Information System (INIS)
BWXT Services, Inc. (BWXS) a subsidiary of BWX Technologies, Inc., one of the Babcock and Wilcox companies, has for some years conducted small scale development of its patented uranyl nitrate Medical Isotope Production System (MIPS). This application of an Aqueous Homogeneous Reactor (AHR) for isotope production was invented by BWXT's Dr. Russell M. Ball in 1997. The MIPS approach targets commercial scale production of medical isotopes, primarily 99Mo, used to supply 99mTc for diagnostic imaging purposes, using a Low Enriched Uranium (LEU) salt solution as the fuel/target. Recent heightened emphasis on controlling use of Highly Enriched Uranium (HEU) throughout the world in support of nuclear non-proliferation goals has motivated increased commercial interest in this safe and cost effective technology. Conceptual designs for commercial application have been developed and efforts are under way to establish a partnership with an established pharmaceutical firm familiar with current 99Mo production technology and operating practice. (author)
Homogenization of resonant chiral metamaterials
DEFF Research Database (Denmark)
Andryieuski, Andrei; Menzel, C.; Rockstuhl, Carsten;
2010-01-01
Homogenization of metamaterials is a crucial issue as it allows to describe their optical response in terms of effective wave parameters as, e.g., propagation constants. In this paper we consider the possible homogenization of chiral metamaterials. We show that for meta-atoms of a certain size a...... critical density exists above which increasing coupling between neighboring meta-atoms prevails a reasonable homogenization. On the contrary, a dilution in excess will induce features reminiscent to photonic crystals likewise prevailing a homogenization. Based on Bloch mode dispersion we introduce an...... analytical criterion for performing the homogenization and a tool to predict the homogenization limit. We show that strong coupling between meta-atoms of chiral metamaterials may prevent their homogenization at all....
Chemical reactions at aqueous interfaces
Vecitis, Chad David
2009-12-01
Interfaces or phase boundaries are a unique chemical environment relative to individual gas, liquid, or solid phases. Interfacial reaction mechanisms and kinetics are often at variance with homogeneous chemistry due to mass transfer, molecular orientation, and catalytic effects. Aqueous interfaces are a common subject of environmental science and engineering research, and three environmentally relevant aqueous interfaces are investigated in this thesis: 1) fluorochemical sonochemistry (bubble-water), 2) aqueous aerosol ozonation (gas-water droplet), and 3) electrolytic hydrogen production and simultaneous organic oxidation (water-metal/semiconductor). Direct interfacial analysis under environmentally relevant conditions is difficult, since most surface-specific techniques require relatively `extreme' conditions. Thus, the experimental investigations here focus on the development of chemical reactors and analytical techniques for the completion of time/concentration-dependent measurements of reactants and their products. Kinetic modeling, estimations, and/or correlations were used to extract information on interfacially relevant processes. We found that interfacial chemistry was determined to be the rate-limiting step to a subsequent series of relatively fast homogeneous reactions, for example: 1) Pyrolytic cleavage of the ionic headgroup of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) adsorbed to cavitating bubble-water interfaces during sonolysis was the rate-determining step in transformation to their inorganic constituents carbon monoxide, carbon dioxide, and fluoride; 2) ozone oxidation of aqueous iodide to hypoiodous acid at the aerosol-gas interface is the rate-determining step in the oxidation of bromide and chloride to dihalogens; 3) Electrolytic oxidation of anodic titanol surface groups is rate-limiting for the overall oxidation of organics by the dichloride radical. We also found chemistry unique to the interface, for example: 1
Homogeneous nucleation of methane hydrates: unrealistic under realistic conditions.
Knott, Brandon C; Molinero, Valeria; Doherty, Michael F; Peters, Baron
2012-12-01
Methane hydrates are ice-like inclusion compounds with importance to the oil and natural gas industry, global climate change, and gas transportation and storage. The molecular mechanism by which these compounds form under conditions relevant to industry and nature remains mysterious. To understand the mechanism of methane hydrate nucleation from supersaturated aqueous solutions, we performed simulations at controlled and realistic supersaturation. We found that critical nuclei are extremely large and that homogeneous nucleation rates are extremely low. Our findings suggest that nucleation of methane hydrates under these realistic conditions cannot occur by a homogeneous mechanism. PMID:23148735
Chae, Bora; Cakiner-Egilmez, Tulay; Desai, Manishi
2013-01-01
Glaucoma is a common eye condition that affects millions of individuals worldwide, making it the second-leading cause of blindness. Because glaucoma is associated with increased IOP level, the primary goal in treatment of glaucoma includes lowering IOP to prevent further progression of the disease. While various surgical interventions exist, medical therapy is currently the first line of treatment. Medical treatment of glaucoma includes topical beta-blockers, alpha-2 agonists, prostaglandins, parasympathomimetics and CAIs. Anti-glaucoma agents help reduce IOP by affecting the production of aqueous humor or increasing the outflow of aqueous through the trabecular or uveoscleral pathway. Choosing an appropriate medical regimen can be challenging and various factors such as efficacy, safety, cost and patient compliance must be considered. First-line treatment is often topical beta-blockers or prostaglandin analogs. However, beta-blocking agents can be associated with systemic side effects and need to be used cautiously in patients with serious concomitant cardiopulmonary disease. Alpha-2 agonists and parasympathomimetics are often considered second- or third-line treatment options but good adjunctive agents. Oral CAIs are often indicated for patients with elevated IOP in an acute setting or for patients resistant to other glaucoma medications and patients who are not good surgical candidates. PMID:23505792
Homogeneous Spaces and Equivariant Embeddings
Timashev, DA
2011-01-01
Homogeneous spaces of linear algebraic groups lie at the crossroads of algebraic geometry, theory of algebraic groups, classical projective and enumerative geometry, harmonic analysis, and representation theory. By standard reasons of algebraic geometry, in order to solve various problems on a homogeneous space it is natural and helpful to compactify it keeping track of the group action, i.e. to consider equivariant completions or, more generally, open embeddings of a given homogeneous space. Such equivariant embeddings are the subject of this book. We focus on classification of equivariant em
Treatment of Pesticides in Wastewater by Heterogeneous and Homogeneous Photocatalysis
Directory of Open Access Journals (Sweden)
Catalina Daniela Stan
2012-01-01
Full Text Available The effect of different heterogeneous and homogeneous photocatalytic systems on the oxidative degradation of mepiquat chloride in aqueous solutions was investigated. In the case of heterogeneous reactions, the influence of five factors was studied: the type of catalyst, photocatalyst concentration, pH, pesticide concentration, and the presence of H2O2 and/or Fe3+. For homogeneous catalysis, other factors were studied: the oxidising agent and the light source. Nearly complete degradation of mepiquat chloride was obtained after about 180 minutes in the presence of an acid medium (pH3 using a UV-A lamp and TiO2P-25 catalyst (0.5 g/L, for an initial pesticide concentration of 10 ppm. Degradation rates corresponding to homogeneous photocatalysis were lower compared to those corresponding to the use of TiO2 as the photocatalyst.
... Facebook Twitter Google Plus Email Print this page Flow of Aqueous Humor Most, but not all, forms ... aqueous humor) produced by the eye's ciliary body flows out freely (follow blue arrow). Aqueous humor flows ...
Perin, Chloé
2010-01-01
We show that any non abelian free group $\\F$ is strongly $\\aleph_0$-homogeneous, i.e. that finite tuples of elements which satisfy the same first-order properties are in the same orbit under $\\Aut(\\F)$. We give a characterization of elements in finitely generated groups which have the same first-order properties as a primitive element of the free group. We deduce as a consequence that most hyperbolic surface groups are not $\\aleph_0$-homogeneous.
Albedo matrices in assembly homogenization
International Nuclear Information System (INIS)
Relations between albedo matrices and a set of diffusion coefficients for a homogeneous medium is considered. The possibility to determine albedo matrices in a homogeneous diffusion medium on the basis of diffusion constants is proved. Relations for the reverse calculation of a set of equivalent diffusion constants using the albedo matrices are obtained. These relations can be used to check the albedo matrices determined by a numerical method. 10 refs.; 2 tabs
Optimization of 200 kW medical isotope production reactor design
International Nuclear Information System (INIS)
One of the primary methods of producing medical isotopes such as 99Mo and 131I is by irradiating uranium targets in heterogeneous reactors. Homogeneous aqueous reactors present a potential alternative to medical isotope production. In response to the global demand for medical isotopes, a concept design of the 200 kW medical isotope production reactor (MIPR) was accomplished by Nuclear Power Institute of China in 2000. Further R and D work was completed in subsequent years, including the optimization of design, reactor thermohydraulic experiments, gas circulation system experiments, etc. Compared with the normal isotope production method such as target irradiation, the MIPR can produce more types of isotope at lower cost and with less radioactive waste generation. (author)
Homogenization of neutronic diffusion models
International Nuclear Information System (INIS)
In order to study and simulate nuclear reactor cores, one needs to access the neutron distribution in the core. In practice, the description of this density of neutrons is given by a system of diffusion equations, coupled by non differential exchange terms. The strong heterogeneity of the medium constitutes a major obstacle to the numerical computation of this models at reasonable cost. Homogenization appears as compulsory. Heuristic methods have been developed since the origin by nuclear physicists, under a periodicity assumption on the coefficients. They consist in doing a fine computation one a single periodicity cell, to solve the system on the whole domain with homogeneous coefficients, and to reconstruct the neutron density by multiplying the solutions of the two computations. The objectives of this work are to provide mathematically rigorous basis to this factorization method, to obtain the exact formulas of the homogenized coefficients, and to start on geometries where two periodical medium are placed side by side. The first result of this thesis concerns eigenvalue problem models which are used to characterize the state of criticality of the reactor, under a symmetry assumption on the coefficients. The convergence of the homogenization process is proved, and formulas of the homogenized coefficients are given. We then show that without symmetry assumptions, a drift phenomenon appears. It is characterized by the mean of a real Bloch wave method, which gives the homogenized limit in the general case. These results for the critical problem are then adapted to the evolution model. Finally, the homogenization of the critical problem in the case of two side by side periodic medium is studied on a one dimensional on equation model. (authors)
Toxicological studies of aqueous extract of Acacia nilotica root
Directory of Open Access Journals (Sweden)
Alli Lukman Adewale
2015-03-01
Full Text Available Acacia nilotica is a widely used plant in traditional medical practice in Northern Nigeria and many African countries. The aim of this study was to determine the toxicological effects of a single dose (acute and of repeated doses (sub-acute administration of aqueous extract of A. nilotica root in rodents, following our earlier study on antiplasmodial activity. In the acute toxicity test, three groups of Swiss albino mice were orally administered aqueous extract of A. nilotica (50, 300 and 2000 mg/kg body weight and signs of toxicity were observed daily for 14 days. In the sub-acute toxicity study, four groups of 12 rats (6 male and 6 female were used. Group 1 received 10 ml/kg b.w distilled water (control, while groups 2, 3 and 4 received 125, 250 and 500 mg/kg b.w of the extract, respectively, for 28 consecutive days by oral gavage. Signs of toxicity/mortality, food and water intake and body weight changes were observed. Biochemical parameters were analysed in both plasma and liver homogenate. In the acute and sub-acute toxicity studies, the extract did not cause mortality. A significant reduction in the activity of lactate dehydrogenase was observed at 250 and 500 mg/kg b.w, while alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase activities were significantly higher than control values at 500 mg/kg b.w. The aqueous extract of A. nilotica was found to be safe in single dose administration in mice but repeated administration of doses higher than 250 mg/kg b.w of the extract for 28 days in rats may cause hepatotoxicity.
Genetic Homogenization of Composite Materials
Directory of Open Access Journals (Sweden)
P. Tobola
2009-04-01
Full Text Available The paper is focused on numerical studies of electromagnetic properties of composite materials used for the construction of small airplanes. Discussions concentrate on the genetic homogenization of composite layers and composite layers with a slot. The homogenization is aimed to reduce CPU-time demands of EMC computational models of electrically large airplanes. First, a methodology of creating a 3-dimensional numerical model of a composite material in CST Microwave Studio is proposed focusing on a sufficient accuracy of the model. Second, a proper implementation of a genetic optimization in Matlab is discussed. Third, an association of the optimization script and a simplified 2-dimensional model of the homogeneous equivalent model in Comsol Multiphysics is proposed considering EMC issues. Results of computations are experimentally verified.
DEFF Research Database (Denmark)
Horn, Anna Frisenfeldt; Barouh, Nathalie; Nielsen, Nina Skall;
2013-01-01
The oxidative stability of 10 % fish oil-in-water emulsions was investigated for emulsions prepared under different homogenization conditions. Homogenization was conducted at two different pressures (5 or 22.5 MPa), and at two different temperatures (22 and 72 °C). Milk proteins were used as the...... decreased the oxidative stability of emulsions with α-lactalbumin and β-lactoglobulin. For both types of emulsions the partitioning of proteins between the interface and the aqueous phase appeared to be important for the oxidative stability. The effect of pre-heating the aqueous phase with the milk proteins...
On $\\delta$-homogeneous Riemannian manifolds
Berestovskii, V. N.; Nikonorov, Yu. G.
2006-01-01
We study in this paper previously defined by V.N. Berestovskii and C.P. Plaut $\\delta$-homogeneous spaces in the case of Riemannian manifolds. Every such manifold has non-negative sectional curvature. The universal covering of any $\\delta$-homogeneous Riemannian manifolds is itself $\\delta$-homogeneous. In turn, every simply connected Riemannian $\\delta$-homogeneous manifold is a direct metric product of an Euclidean space and compact simply connected indecomposable homogeneous manifolds; all...
Czech Academy of Sciences Publication Activity Database
Mayor, G.; Mesiar, Radko; Torrens, J.
2008-01-01
Roč. 44, č. 6 (2008), s. 745-756. ISSN 0023-5954 R&D Projects: GA ČR GA402/08/0618 Institutional research plan: CEZ:AV0Z10750506 Keywords : copula * diagonal section * quasi-homegeneity Subject RIV: BA - General Mathematics Impact factor: 0.281, year: 2008 http://library.utia.cas.cz/separaty/2008/E/mesiar-on quasi-homogeneous copulas.pdf
Self-consolidating concrete homogeneity
Jarque, J. C.; Parra, C.; Valcuende, M.O.
2007-01-01
Concrete instability may lead to the non-uniform distribution of its properties. The homogeneity of self-consolidating concrete in vertically cast members was therefore explored in this study, analyzing both resistance to segregation and pore structure uniformity. To this end, two series of concretes were prepared, self-consolidating and traditional vibrated materials, with different w/c ratios and types of cement. The results showed that selfconsolidating concretes exhibit high resistance to...
Homogenized Elasticity of Martensitic Microstructures
Czech Academy of Sciences Publication Activity Database
Seiner, Hanuš; Glatz, Ondřej; Landa, Michal
Freiburg : Fraunhofer Verlag, 2010 - (Gumbsch, P.; van der Giessen, E.), s. 546-549 ISBN 978-3-8396-0166-2. [International Conference on Multiscale Materials Modelling MMM2010 /5./. Freiburrg (DE), 04.10.2010-08.10.2010] R&D Projects: GA ČR GP202/09/P164 Institutional research plan: CEZ:AV0Z20760514 Keywords : martensitic transformations * homogenization procedure * 1st order laminate Subject RIV: BM - Solid Matter Physics ; Magnetism
Homogeneous determination of maximum magnitude
Meletti, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia; D'Amico, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia; Martinelli, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia
2010-01-01
This deliverable represents the result of the activities performed by a working group at INGV. The main object of the Task 3.5 is defined in the Description of Work. This task will produce a homogeneous assessment (possibly multiple models) of the distribution of the expected Maximum Magnitude for earthquakes expected in various tectonic provinces of Europe, to serve as input for the computation and validation of seismic hazard. This goal will be achieved by combining input from earthqu...
Homogenization in elasto-plasticity
Orlik, J
2008-01-01
The theory of the two-scale convergence was applied to homogenization of elasto-plastic composites with a periodic structure and exponential hardening law. The theory is based on the fact that the elastic as well as the plastic part of the stress field two-scale converges to a limit, which is factorized by parts, depending only on macroscopic characteristics, represented in terms of corresponding part of the homogenised stress tensor and only on stress concentration tensor, related to the mic...
Properties of isometrically homogeneous curves
Donne, Enrico Le
2011-01-01
This paper is devoted to the study of isometrically homogeneous spaces from the view point of metric geometry. Mainly we focus on those spaces that are homeomorphic to lines. We show that one can reduce the study to those distances on $\\R$ that are translation invariant. We study possible values of various metric dimensions of such spaces. One of the main results is the equivalence of two properties: the first one is linear connectedness and the second one is 1-dimensionality, with respect to Nagata dimension. Several concrete pathological examples are provided.
Homogenization scheme for acoustic metamaterials
Yang, Min
2014-02-26
We present a homogenization scheme for acoustic metamaterials that is based on reproducing the lowest orders of scattering amplitudes from a finite volume of metamaterials. This approach is noted to differ significantly from that of coherent potential approximation, which is based on adjusting the effective-medium parameters to minimize scatterings in the long-wavelength limit. With the aid of metamaterials’ eigenstates, the effective parameters, such as mass density and elastic modulus can be obtained by matching the surface responses of a metamaterial\\'s structural unit cell with a piece of homogenized material. From the Green\\'s theorem applied to the exterior domain problem, matching the surface responses is noted to be the same as reproducing the scattering amplitudes. We verify our scheme by applying it to three different examples: a layered lattice, a two-dimensional hexagonal lattice, and a decorated-membrane system. It is shown that the predicted characteristics and wave fields agree almost exactly with numerical simulations and experiments and the scheme\\'s validity is constrained by the number of dominant surface multipoles instead of the usual long-wavelength assumption. In particular, the validity extends to the full band in one dimension and to regimes near the boundaries of the Brillouin zone in two dimensions.
ISOTOPE METHODS IN HOMOGENEOUS CATALYSIS.
Energy Technology Data Exchange (ETDEWEB)
BULLOCK,R.M.; BENDER,B.R.
2000-12-01
The use of isotope labels has had a fundamentally important role in the determination of mechanisms of homogeneously catalyzed reactions. Mechanistic data is valuable since it can assist in the design and rational improvement of homogeneous catalysts. There are several ways to use isotopes in mechanistic chemistry. Isotopes can be introduced into controlled experiments and followed where they go or don't go; in this way, Libby, Calvin, Taube and others used isotopes to elucidate mechanistic pathways for very different, yet important chemistries. Another important isotope method is the study of kinetic isotope effects (KIEs) and equilibrium isotope effect (EIEs). Here the mere observation of where a label winds up is no longer enough - what matters is how much slower (or faster) a labeled molecule reacts than the unlabeled material. The most careti studies essentially involve the measurement of isotope fractionation between a reference ground state and the transition state. Thus kinetic isotope effects provide unique data unavailable from other methods, since information about the transition state of a reaction is obtained. Because getting an experimental glimpse of transition states is really tantamount to understanding catalysis, kinetic isotope effects are very powerful.
Significance tests and sample homogeneity loophole
Kupczynski, Marian
2015-01-01
In their recent comment, published in Nature, Jeffrey T.Leek and Roger D.Peng discuss how P-values are widely abused in null hypothesis significance testing . We agree completely with them and in this short comment we discuss the importance of sample homogeneity tests. No matter with how much scrutiny data are gathered if homogeneity tests are not performed the significance tests suffer from sample homogeneity loophole and the results may not be trusted. For example sample homogeneity loophol...
Improving homogeneity by dynamic speed limit systems.
Nes, N. van Brandenberg, S. & Twisk, D.A.M.
2010-01-01
Homogeneity of driving speeds is an important variable in determining road safety; more homogeneous driving speeds increase road safety. This study investigates the effect of introducing dynamic speed limit systems on homogeneity of driving speeds. A total of 46 subjects twice drove a route along 12
The homogeneous geometries of real hyperbolic space
DEFF Research Database (Denmark)
Castrillón López, Marco; Gadea, Pedro Martínez; Swann, Andrew Francis
We describe the holonomy algebras of all canonical connections of homogeneous structures on real hyperbolic spaces in all dimensions. The structural results obtained then lead to a determination of the types, in the sense of Tricerri and Vanhecke, of the corresponding homogeneous tensors. We use...... our analysis to show that the moduli space of homogeneous structures on real hyperbolic space has two connected components....
Projective duality and homogeneous spaces
Tevelev, E A
2006-01-01
Projective duality is a very classical notion naturally arising in various areas of mathematics, such as algebraic and differential geometry, combinatorics, topology, analytical mechanics, and invariant theory, and the results in this field were until now scattered across the literature. Thus the appearance of a book specifically devoted to projective duality is a long-awaited and welcome event. Projective Duality and Homogeneous Spaces covers a vast and diverse range of topics in the field of dual varieties, ranging from differential geometry to Mori theory and from topology to the theory of algebras. It gives a very readable and thorough account and the presentation of the material is clear and convincing. For the most part of the book the only prerequisites are basic algebra and algebraic geometry. This book will be of great interest to graduate and postgraduate students as well as professional mathematicians working in algebra, geometry and analysis.
... womb (uterus). There are different types of medical abortions: Therapeutic medical abortion is done because the woman has ... Therapeutic medical abortion; Elective medical abortion; Induced abortion; Nonsurgical abortion
Polyurethane phantoms with homogeneous and nearly homogeneous optical properties
Keränen, Ville T.; Mäkynen, Anssi J.; Dayton, Amanda L.; Prahl, Scott A.
2010-02-01
Phantoms with controlled optical properties are often used for calibration and standardization. The phantoms are typically prepared by adding absorbers and scatterers to a clear host material. It is usually assumed that the scatterers and absorbers are uniformly dispersed within the medium. To explore the effects of this assumption, we prepared paired sets of polyurethane phantoms (both with identical masses of absorber, India ink and scatterer, titanium dioxide). Polyurethane phantoms were made by mixing two polyurethane parts (a and b) together and letting them cure in a polypropylene container. The mixture was degassed before curing to ensure a sample without bubbles. The optical properties were controlled by mixing titanium dioxide or India ink into polyurethane part (a or b) before blending the parts together. By changing the mixing sequence, we could change the aggregation of the scattering and absorbing particles. Each set had one sample with homogeneously dispersed scatterers and absorbers, and a second sample with slightly aggregated scatterers or absorbers. We found that the measured transmittance could easily vary by a factor of twenty. The estimated optical properties (using the inverse adding-doubling method) indicate that when aggregation is present, the optical properties are no longer proportional to the concentrations of absorbers or scatterers.
Self-thinning and neutralizing thickened aqueous liquid
Energy Technology Data Exchange (ETDEWEB)
Lybarger, J.H.; Scheuerman, R.F.
1979-04-17
A thickened aqueous liquid is described for use in well treating processes, such as sand or gravel packing, fracturing, fluid-diverting, selective-plugging, fluid-displacing etc. The thickened aqueous liquid consists of an aqueous solution containing 1) an acid-reactive cellulosic water thickener in an amount ranging from 0.1 to 4% by weight of the solution to provide viscosities which at 80/sup 0/F range from 100 to 51,000 cp; 2) an amount and composition of substantially homogeneously distributed acidifying material sufficient to cause a significant decrease in the viscosity of the solution after a selected time-temperature exposure; and 3) an amount and composition of substantially homogeneously-distributed relatively slowly-reactive pH-increasing material sufficient to subsequently raise the pH of the solution to a selected relatively neutral value after an increased time. 10 claims.
Yoshio Kobayashi; Naomichi Takahashi; Takafumi Maeda; Takehiro Yonezawa; Kazuhiko Yamasaki
2015-01-01
The present work proposes a method to fabricate indium tin oxide (ITO) particles using precursor particles synthesized with a combination of a homogeneous precipitation method and a seeding technique, and it also describes their electronic conductivity properties. Seed nanoparticles were produced using a co-precipitation method with aqueous solutions of indium (III) chloride, tin (IV) chloride aqueous solution and sodium hydroxide. Three types of ITO nanoparticles were fabricated. The first t...
Homogeneous modes of cosmological instantons
International Nuclear Information System (INIS)
We discuss the O(4) invariant perturbation modes of cosmological instantons. These modes are spatially homogeneous in Lorentzian spacetime and thus not relevant to density perturbations. But their properties are important in establishing the meaning of the Euclidean path integral. If negative modes are present, the Euclidean path integral is not well defined, but may nevertheless be useful in an approximate description of the decay of an unstable state. When gravitational dynamics is included, counting negative modes requires a careful treatment of the conformal factor problem. We demonstrate that for an appropriate choice of coordinate on phase space, the second order Euclidean action is bounded below for normalized perturbations and has a finite number of negative modes. We prove that there is a negative mode for many gravitational instantons of the Hawking-Moss or ColemanendashDe Luccia type, and discuss the associated spectral flow. We also investigate Hawking-Turok constrained instantons, which occur in a generic inflationary model. Implementing the regularization and constraint proposed by Kirklin, Turok and Wiseman, we find that those instantons leading to substantial inflation do not possess negative modes. Using an alternate regularization and constraint motivated by reduction from five dimensions, we find a negative mode is present. These investigations shed new light on the suitability of Euclidean quantum gravity as a potential description of our universe
Pharmaceutical Industry Oriented Homogeneous Catalysis
Institute of Scientific and Technical Information of China (English)
Zhang Xumu
2004-01-01
Chiral therapeutics already makes up over one-third of pharmaceutical drugs currently sold worldwide. This is a growing industry with global chiral drug sales for 2002 increasing by 12%to $160 billion (Technology Catalysts International) of a total drug market of $410bn. The increasing demand to produce enantiomerically pure pharmaceuticals, agrochemicals, flavors, and other fine chemicals has advanced the field of asymmetric catalytic technologies.We aim to become a high value technology provider and partner in the chiral therapeutics industry by offering proprietary catalysts, novel building blocks, and collaborative synthetic solutions. In decade, we have developed a set of novel chiral homogeneous phosphorus ligands such as Binaphane, Me-KetalPhos, TangPhos, f-Binaphane, Me-f-KetalPhos, C4TunePhos and Binapine,which we called Chiral Ligand ToolKit. Complementing the ToolKit, (R, S, S, R)-DIOP*, T-Phos,o-BIPHEP, o-BINAPO and FAP were added recently[1].These ligands can be applied to a broad variety of drug structural features by asymmetric hydrogenation of dehydroamino acid derivatives, enamides, unsatisfied acids and esters, ketones,beta ketoesters, imines and cyclic imines. And ligand FAP had been apllied succefully in allylic alkylation and [3+2] cycloaddition.
A Class of Homogeneous Einstein Manifolds
Institute of Scientific and Technical Information of China (English)
Yifang KANG; Ke LIANG
2006-01-01
A Riemannian manifold (M,g) is called Einstein manifold if its Ricci tensor satisfies r=c·g for some constant c. General existence results are hard to obtain,e.g., it is as yet unknown whether every compact manifold admits an Einstein metric. A natural approach is to impose additional homogeneous assumptions. M. Y. Wang and W. Ziller have got some results on compact homogeneous space G/H. They investigate standard homogeneous metrics, the metric induced by Killing form on G/H, and get some classification results. In this paper some more general homogeneous metrics on some homogeneous space G/H are studies, and a necessary and sufficient condition for this metric to be Einstein is given. The authors also give some examples of Einstein manifolds with non-standard homogeneous metrics.
Model Misspecification: Finite Mixture or Homogeneous?
Tarpey, Thaddeus; Yun, Dong; Petkova, Eva
2008-01-01
A common problem in statistical modelling is to distinguish between finite mixture distribution and a homogeneous non-mixture distribution. Finite mixture models are widely used in practice and often mixtures of normal densities are indistinguishable from homogenous non-normal densities. This paper illustrates what happens when the EM algorithm for normal mixtures is applied to a distribution that is a homogeneous non-mixture distribution. In particular, a population-based EM algorithm for fi...
A literature review on biotic homogenization
Guangmei Wang; Jingcheng Yang; Chuangdao Jiang; Hongtao Zhao; Zhidong Zhang
2009-01-01
Biotic homogenization is the process whereby the genetic, taxonomic and functional similarity of two or more biotas increases over time. As a new research agenda for conservation biogeography, biotic homogenization has become a rapidly emerging topic of interest in ecology and evolution over the past decade. However, research on this topic is rare in China. Herein, we introduce the development of the concept of biotic homogenization, and then discuss methods to quantify its three components (...
The Homogeneity Scale of the universe
Ntelis, Pierros
2016-01-01
In this study, we probe the cosmic homogeneity with the BOSS CMASS galaxy sample in the redshift region of $0.43 < z < 0.7$. We use the normalised counts-in-spheres estimator $\\mathcal{N}(
Self-consolidating concrete homogeneity
Directory of Open Access Journals (Sweden)
Jarque, J. C.
2007-08-01
Full Text Available Concrete instability may lead to the non-uniform distribution of its properties. The homogeneity of self-consolidating concrete in vertically cast members was therefore explored in this study, analyzing both resistance to segregation and pore structure uniformity. To this end, two series of concretes were prepared, self-consolidating and traditional vibrated materials, with different w/c ratios and types of cement. The results showed that selfconsolidating concretes exhibit high resistance to segregation, albeit slightly lower than found in the traditional mixtures. The pore structure in the former, however, tended to be slightly more uniform, probably as a result of less intense bleeding. Such concretes are also characterized by greater bulk density, lower porosity and smaller mean pore size, which translates into a higher resistance to pressurized water. For pore diameters of over about 0.5 Î¼m, however, the pore size distribution was found to be similar to the distribution in traditional concretes, with similar absorption rates.En este trabajo se estudia la homogeneidad de los hormigones autocompactantes en piezas hormigonadas verticalmente, determinando su resistencia a la segregación y la uniformidad de su estructura porosa, dado que la pérdida de estabilidad de una mezcla puede conducir a una distribución no uniforme de sus propiedades. Para ello se han fabricado dos tipos de hormigones, uno autocompactante y otro tradicional vibrado, con diferentes relaciones a/c y distintos tipos de cemento. Los resultados ponen de manifiesto que los hormigones autocompactantes presentan una buena resistencia a la segregación, aunque algo menor que la registrada en los hormigones tradicionales. A pesar de ello, su estructura porosa tiende a ser ligeramente más uniforme, debido probablemente a un menor sangrado. Asimismo, presentan una mayor densidad aparente, una menor porosidad y un menor tamaño medio de poro, lo que les confiere mejores
Bacterial Acclimation Inside an Aqueous Battery
Dong, Dexian; Chen, Baoling; Chen, P
2015-01-01
Specific environmental stresses may lead to induced genomic instability in bacteria, generating beneficial mutants and potentially accelerating the breeding of industrial microorganisms. The environmental stresses inside the aqueous battery may be derived from such conditions as ion shuttle, pH gradient, free radical reaction and electric field. In most industrial and medical applications, electric fields and direct currents are used to kill bacteria and yeast. However, the present study focu...
Investigations into homogenization of electromagnetic metamaterials
DEFF Research Database (Denmark)
Clausen, Niels Christian Jerichau
This dissertation encompasses homogenization methods, with a special interest into their applications to metamaterial homogenization. The first method studied is the Floquet-Bloch method, that is based on the assumption of a material being infinite periodic. Its field can then be expanded in term...
CLASSIFICATION OF CUBIC PARAMETERIZED HOMOGENEOUS VECTOR FIELDS
Institute of Scientific and Technical Information of China (English)
Karnal H.Yasir; TANG Yun
2002-01-01
In this paper the cubic homogeneous parameterized vector fields are studied.The classification of the phase portrait near the critical point is presented. This classification is an extension of the result given by Takens to the cubic homogeneous parameterized vector fields with six parameters.
CLASSIFICATION OF CUBIC PARAMETERIZED HOMOGENEOUS VECTOR FIELDS
Institute of Scientific and Technical Information of China (English)
KamalH.Yasir; TNAGYun
2002-01-01
In this paper the cubic homogeneous parameterized vector fields are studied.The classification of the phase portrait near the critical point is presented.This classification is an extension of the result given by takens to the cubic homogeneous parameterized vector fields with six parameters.
s-Numbers sequences for homogeneous polynomials
Caliskan, Erhan; Rueda, Pilar
2015-01-01
We extend the well known theory of $s$-numbers of linear operators to homogeneous polynomials defined between Banach spaces. Approximation, Kolmogorov and Gelfand numbers of polynomials are introduced and some well-known results of the linear and multilinear settings are obtained for homogeneous polynomials.
DETERMINISTIC HOMOGENIZATION OF QUASILINEAR DAMPED HYPERBOLIC EQUATIONS
Institute of Scientific and Technical Information of China (English)
Gabriel Nguetseng; Hubert Nnang; Nils Svanstedt
2011-01-01
Deterministic homogenization is studied for quasilinear monotone hyperbolic problems with a linear damping term.It is shown by the sigma-convergence method that the sequence of solutions to a class of multi-scale highly oscillatory hyperbolic problems converges to the solution to a homogenized quasilinear hyperbolic problem.
Multilevel Monte Carlo Approaches for Numerical Homogenization
Efendiev, Yalchin R.
2015-10-01
In this article, we study the application of multilevel Monte Carlo (MLMC) approaches to numerical random homogenization. Our objective is to compute the expectation of some functionals of the homogenized coefficients, or of the homogenized solutions. This is accomplished within MLMC by considering different sizes of representative volumes (RVEs). Many inexpensive computations with the smallest RVE size are combined with fewer expensive computations performed on larger RVEs. Likewise, when it comes to homogenized solutions, different levels of coarse-grid meshes are used to solve the homogenized equation. We show that, by carefully selecting the number of realizations at each level, we can achieve a speed-up in the computations in comparison to a standard Monte Carlo method. Numerical results are presented for both one-dimensional and two-dimensional test-cases that illustrate the efficiency of the approach.
... this page: //medlineplus.gov/ency/patientinstructions/000899.htm Medical marijuana To use the sharing features on this ... have legalized marijuana for medical use. How Does Medical Marijuana Work? Medical marijuana may be: Smoked Vaporized ...
String pair production in non homogeneous backgrounds
Bolognesi, S.; Rabinovici, E.; Tallarita, G.
2016-04-01
We consider string pair production in non homogeneous electric backgrounds. We study several particular configurations which can be addressed with the Euclidean world-sheet instanton technique, the analogue of the world-line instanton for particles. In the first case the string is suspended between two D-branes in flat space-time, in the second case the string lives in AdS and terminates on one D-brane (this realizes the holographic Schwinger effect). In some regions of parameter space the result is well approximated by the known analytical formulas, either the particle pair production in non-homogeneous background or the string pair production in homogeneous background. In other cases we see effects which are intrinsically stringy and related to the non-homogeneity of the background. The pair production is enhanced already for particles in time dependent electric field backgrounds. The string nature enhances this even further. For spacial varying electrical background fields the string pair production is less suppressed than the rate of particle pair production. We discuss in some detail how the critical field is affected by the non-homogeneity, for both time and space dependent electric field backgrouds. We also comment on what could be an interesting new prediction for the small field limit. The third case we consider is pair production in holographic confining backgrounds with homogeneous and non-homogeneous fields.
Benchmarking homogenization algorithms for monthly data
Directory of Open Access Journals (Sweden)
V. K. C. Venema
2012-01-01
Full Text Available The COST (European Cooperation in Science and Technology Action ES0601: advances in homogenization methods of climate series: an integrated approach (HOME has executed a blind intercomparison and validation study for monthly homogenization algorithms. Time series of monthly temperature and precipitation were evaluated because of their importance for climate studies and because they represent two important types of statistics (additive and multiplicative. The algorithms were validated against a realistic benchmark dataset. The benchmark contains real inhomogeneous data as well as simulated data with inserted inhomogeneities. Random independent break-type inhomogeneities with normally distributed breakpoint sizes were added to the simulated datasets. To approximate real world conditions, breaks were introduced that occur simultaneously in multiple station series within a simulated network of station data. The simulated time series also contained outliers, missing data periods and local station trends. Further, a stochastic nonlinear global (network-wide trend was added.
Participants provided 25 separate homogenized contributions as part of the blind study. After the deadline at which details of the imposed inhomogeneities were revealed, 22 additional solutions were submitted. These homogenized datasets were assessed by a number of performance metrics including (i the centered root mean square error relative to the true homogeneous value at various averaging scales, (ii the error in linear trend estimates and (iii traditional contingency skill scores. The metrics were computed both using the individual station series as well as the network average regional series. The performance of the contributions depends significantly on the error metric considered. Contingency scores by themselves are not very informative. Although relative homogenization algorithms typically improve the homogeneity of temperature data, only the best ones improve
Self-thinning and neutralizing thickened aqueous liquid
Energy Technology Data Exchange (ETDEWEB)
Lybarger, J.H.; Scheuerman, R.F.
1975-07-01
A method is described for thickening water and then reducing the viscosity at a selected time. The thickened aqueous liquid contains (1) enough dissolved acid-reactive cellulosic water thickener to provide a selected viscosity, (2) an amount and composition of substantially homogeneously distributed acidifying material sufficient to cause a decrease in the viscosity of the solution after a selected time-temperature exposure, and (3) an amount and composition of substantially homogeneously distributed relatively slowly reactive pH-increasing material sufficient to raise the pH of the solution to a selected substantially neutral value after an additional time. (5 claims)
Higher Order Macro Coefficients in Periodic Homogenization
Conca, Carlos; San Martin, Jorge; Smaranda, Loredana; Vanninathan, Muthusamy
2011-09-01
A first set of macro coefficients known as the homogenized coefficients appear in the homogenization of PDE on periodic structures. If energy is increased or scale is decreased, these coefficients do not provide adequate approximation. Using Bloch decomposition, it is first realized that the above coefficients correspond to the lowest energy and the largest scale. This naturally paves the way to introduce other sets of macro coefficients corresponding to higher energies and lower scales which yield better approximation. The next task is to compare their properties with those of the homogenized coefficients. This article reviews these developments along with some new results yet to be published.
Higher Order Macro Coefficients in Periodic Homogenization
Energy Technology Data Exchange (ETDEWEB)
Conca, Carlos; San Martin, Jorge [Departamento de IngenierIa Matematica, Facultad de Ciencias Fisicas y Matematicas, Universidad de Chile and Centro de Modelamiento Matematico, UMR 2071 CNRS-UChile, Casilla 170/3 - Correo 3, Santiago (Chile); Smaranda, Loredana [Department of Mathematics, Faculty of Mathematics and Computer Science, University of Pitesti, 110040 Pitesti, Str. Targu din Vale Nr.1, Arges (Romania); Vanninathan, Muthusamy, E-mail: cconca@dim.uchile.cl, E-mail: jorge@dim.uchile.cl, E-mail: smaranda@dim.uchile.cl, E-mail: vanni@math.tifrbng.res.in [TIFR-CAM, Post Bag 6503, GKVK Post, Bangalore - 560065 (India)
2011-09-15
A first set of macro coefficients known as the homogenized coefficients appear in the homogenization of PDE on periodic structures. If energy is increased or scale is decreased, these coefficients do not provide adequate approximation. Using Bloch decomposition, it is first realized that the above coefficients correspond to the lowest energy and the largest scale. This naturally paves the way to introduce other sets of macro coefficients corresponding to higher energies and lower scales which yield better approximation. The next task is to compare their properties with those of the homogenized coefficients. This article reviews these developments along with some new results yet to be published.
Homogeneous phosphorus of silicon by neutron transmutation
International Nuclear Information System (INIS)
The manufacture of high-voltage power semiconductors requires a homogeneous phosphorus doping of silicon within extremely narrow limits. It was the aim of the investigations to develop neutron irradiation as a means to homogeneously dope silicon with phosphorus on an industrial scale. Special attention was given to the selection of suitable reactor positions, the annealing of the irradiation damage, and the electrical properties of the devices. The experience with the application of neutron irradiated silicon for a wide spectrum of devices shows that expected homogeneity and aiming accuracy with respect to the doping can be reached with high reliability. (orig.) 891 ORU/orig. 892 MB
Three-dimensional homogeneous generalized Ricci solitons
Calvaruso, Giovanni
2015-01-01
We study three-dimensional generalized Ricci solitons, both in Riemannian and Lorentzian settings. We shall determine their homogeneous models, classifying left-invariant generalized Ricci solitons on three-dimensional Lie groups.
Homogeneous cosmological models in Yang's gravitation theory
Fennelly, A. J.; Pavelle, R.
1979-01-01
We present a dynamic, spatially homogeneous solution of Yang's pure space gravitational field equations which is non-Einsteinian. The predictions of this cosmological model seem to be at variance with observations.
Lie superalgebras with some homogeneous structures
Ayadi, Imen; Benayadi, Saïd
2010-01-01
We generalize to the case of Lie superalgebras the classical symplectic double extension of symplectic Lie algebras introduced in [2]. We use this concept to give an inductive description of nilpotent homogeneous-symplectic Lie superalgebras. Several examples are included to show the existence of homogeneous quadratic symplectic Lie superalgebras other than even-quadratic even-symplectic considered in [6]. We study the structures of even (resp. odd)-quadratic odd (resp. even)-symplectic Lie superalgebras and odd-quadratic odd-symplectic Lie superalgebras and we give its inductive descriptions in terms of quadratic generalized double extensions and odd quadratic generalized double extensions. This study complete the inductive descriptions of homogeneous quadratic symplectic Lie superalgebras started in [6]. Finally, we generalize to the case of homogeneous quadratic symplectic Lie superargebras some relations between even-quadratic even-symplectic Lie superalgebras and Manin superalgebras established in [6].
On homogeneous Einstein (α , β) -metrics
Yan, Zaili; Deng, Shaoqiang
2016-05-01
In this paper, we study homogeneous Einstein (α , β) -metrics. First, we deduce a formula for Ricci curvature of a homogeneous (α , β) -metric. Based on this formula, we obtain a sufficient and necessary condition for a compact homogeneous (α , β) -metric to be Einstein and with vanishing S-curvature. Moreover, we prove that any homogeneous Ricci flat (α , β) space with vanishing S-curvature must be a Minkowski space. Finally, we consider left invariant Einstein (α , β) -metrics on Lie groups with negative Ricci constant. Under some appropriate conditions, we show that the underlying Lie groups must be two step solvable. We also present a more convenient sufficient and necessary condition for the metric to be Einstein in this special case.
Spatial homogenization of diffusion theory parameters
International Nuclear Information System (INIS)
It is common practice in the determination of nuclear reactor criticality and power distributions to introduce two stages of homogenization. This paper will be concerned with the second stage in which group diffusion parameters for homogenized fuel rod cells, explicitly represented control rods, poison lumps and structural materials are further homogenized over fuel assemblies. We first extend some work by Kollas and Henry (1976) dealing with the question of whether ''exact'' equivalent homogenized diffusion theory parameters exist. We prove that, if an assembly composed of heterogeneous slabs can be described by group-diffusion theory, it is possible to define group parameters spatially constant over the entire assembly that reproduce exactly the average reaction rates and leakage rates of that assembly
Homogenization of ordinary and linear transport equations
Peirone, Roberto
1996-01-01
The homogenization of first order ordinary differential equations in $\\mathbb{R}^N$ and associated linear transport equations are studied. We prove the equivalence between $G$-convergence and strong $G$-convergence for the ordinary equations. We give a sufficient condition, which is also necessary in the autonomous case, for the weak homogenization of the linear transport equations. This condition is satisfied when div$_x f=0$.
Layout optimization using the homogenization method
Suzuki, Katsuyuki; Kikuchi, Noboru
A generalized layout problem involving sizing, shape, and topology optimization is solved by using the homogenization method for three-dimensional linearly elastic shell structures in order to seek a possibility of establishment of an integrated design system of automotive car bodies, as an extension of the previous work by Bendsoe and Kikuchi. A formulation of a three-dimensional homogenized shell, a solution algorithm, and several examples of computing the optimum layout are presented in this first part of the two articles.
Bloch Approximation in Homogenization and Applications
Conca Rosende, Carlos; Orive, R.; Vanninathan, Muthusamy
2002-01-01
The classical problem of homogenization of elliptic operators with periodically oscillating coefficients is revisited in this paper. As is well known, the homogenization process in a classical framework is concerned with the study of asymptotic behavior of solutions $u^\\varepsilon$ of boundary value problems associated with such operators when the period $\\varepsilon>0$ of the coefficients is small. In a previous work by C. Conca and M. Vanninathan [SIAM J. Appl. Math., 57 (1997), pp. 1639--1...
Layout optimization using the homogenization method
Suzuki, Katsuyuki; Kikuchi, Noboru
1993-01-01
A generalized layout problem involving sizing, shape, and topology optimization is solved by using the homogenization method for three-dimensional linearly elastic shell structures in order to seek a possibility of establishment of an integrated design system of automotive car bodies, as an extension of the previous work by Bendsoe and Kikuchi. A formulation of a three-dimensional homogenized shell, a solution algorithm, and several examples of computing the optimum layout are presented in this first part of the two articles.
On homogeneous nontransitive binary perfect code
Mogilnykh, I. Yu.; Solov'eva, F. I.
2014-01-01
Studying binary perfect codes we show the existence of homogeneous nontransitive codes. Thus, as far as perfect codes are concerned, the propelinear codes are strictly contained in transitive codes, wheresas homogeneous codes form a strict subclass of transitive codes. In the work we deduce a necessary and sufficient condition for transitivity of perfect binary codes of rank one more than that of Hamming code. The paper is in Russian.
Significance tests and sample homogeneity loophole
Kupczynski, Marian
2015-01-01
In their recent comment, published in Nature, Jeffrey T.Leek and Roger D.Peng discuss how P-values are widely abused in null hypothesis significance testing . We agree completely with them and in this short comment we discuss the importance of sample homogeneity tests. No matter with how much scrutiny data are gathered if homogeneity tests are not performed the significance tests suffer from sample homogeneity loophole and the results may not be trusted. For example sample homogeneity loophole was not closed in the experiment testing local realism in which a significant violation of Eberhard inequality was found. We are not surprised that Bell type inequalities are violated since if the contextual character of quantum observables is properly taken into account these inequalities cannot be proven. However in order to trust the significance of the violation sample homogeneity loophole must be closed. Therefore we repeat after Jeffrey T.Leek and Roger D.Peng that sample homogeneity loophole is probably just the ...
Ototoxic Medications (Medication Effects)
... effects of the medications on your hearing and balance systems. The team will discuss with you how these side effects will affect your quality of life. What are the effects I may notice from ... speech is affected. Balance problems can also occur as a result of ...
Therapeutic medical abortion; Elective medical abortion; Induced abortion; Nonsurgical abortion ... A medical, or nonsurgical, abortion can be done within 7 weeks from the first day of the woman's last ...
Aqueous polyethylene oxide solutions
International Nuclear Information System (INIS)
A number of aspects concerning the reorientation of polymer, water and ion hydration complexes have been studied in aqueous solution of polyethylene oxide (PEO). The polymer dynamics are investigated by 1H-PEO and 13C-PEO nuclear relaxation experiments. 162 refs.; 30 figs.; 19 tabs
Homogeneous and heterogeneous aqueous phase oxidation of phenol with fenton-like processes
Messele, Selamawit Ashagre
2014-01-01
In the last decades, various chemical oxidation techniques have been developed to overcome the inconveniences associated to conventional treatment of industrial wastewaters. Advanced oxidation processes (AOPs) have been reported to be effective for the degradation of soluble organic contaminants from wastewaters containing non-biodegradable organic pollutants, because they can often provide an almost total degradation, under reasonably mild conditions of temperature and pressure. Among them, ...
Ahmad, R.
2016-07-01
This article reports an unbiased analysis for the water based rod shaped alumina nanoparticles by considering both the homogeneous and non-homogeneous nanofluid models over the coupled nanofluid-surface interface. The mechanics of the surface are found for both the homogeneous and non-homogeneous models, which were ignored in previous studies. The viscosity and thermal conductivity data are implemented from the international nanofluid property benchmark exercise. All the simulations are being done by using the experimentally verified results. By considering the homogeneous and non-homogeneous models, the precise movement of the alumina nanoparticles over the surface has been observed by solving the corresponding system of differential equations. For the non-homogeneous model, a uniform temperature and nanofluid volume fraction are assumed at the surface, and the flux of the alumina nanoparticle is taken as zero. The assumption of zero nanoparticle flux at the surface makes the non-homogeneous model physically more realistic. The differences of all profiles for both the homogeneous and nonhomogeneous models are insignificant, and this is due to small deviations in the values of the Brownian motion and thermophoresis parameters.
A new concept of equivalent homogenization method
International Nuclear Information System (INIS)
A new concept of equivalent homogenization is proposed. The concept employs new set of homogenized parameters: homogenized cross sections (XS) and interface matrix (IM), which relates partial currents at the cell interfaces. The idea of interface matrix generalizes the idea of discontinuity factors (DFs), proposed and developed by K. Koebke and K. Smith. The offered concept covers both those of K. Koebke and K. Smith; both of them can be simulated within framework of new concept. Also, the offered concept covers Siemens KWU approach for baffle/reflector simulation, where the equivalent homogenized reflector XS are derived from the conservation of response matrix at the interface in 1D simi-infinite slab geometry. The IM and XS of new concept satisfy the same assumption about response matrix conservation in 1D semi-infinite slab geometry. It is expected that the new concept provides more accurate approximation of heterogeneous cell, especially in case of the steep flux gradients at the cell interfaces. The attractive shapes of new concept are: improved accuracy, simplicity of incorporation in the existing codes, equal numerical expenses in comparison to the K. Smith's approach. The new concept is useful for: (a) explicit reflector/baffle simulation; (b) control blades simulation; (c) mixed UO2/MOX core simulation. The offered model has been incorporated in the finite difference code and in the nodal code PANDOX. The numerical results show good accuracy of core calculations and insensitivity of homogenized parameters with respect to in-core conditions. 9 figs., 7 refs. (Author)
Exploring an approximation for the homogeneous freezing temperature of water droplets
O, Kuan-Ting; Wood, Robert
2016-06-01
In this work, based on the well-known formulae of classical nucleation theory (CNT), the temperature TNc = 1 at which the mean number of critical embryos inside a droplet is unity is derived from the Boltzmann distribution function and explored as an approximation for homogeneous freezing temperature of water droplets. Without including the information of the applied cooling rate γcooling and the number of observed droplets Ntotal_droplets in the calculation, the approximation TNc = 1 is able to reproduce the dependence of homogeneous freezing temperature on drop size V and water activity aw of aqueous drops observed in a wide range of experimental studies for droplet diameter > 10 µm and aw > 0.85, suggesting the effect of γcooling and Ntotal_droplets may be secondary compared to the effect of V and aw on homogeneous freezing temperatures in these size and water activity ranges under realistic atmospheric conditions. We use the TNc = 1 approximation to argue that the distribution of homogeneous freezing temperatures observed in the experiments may be partly explained by the spread in the size distribution of droplets used in the particular experiment. It thus appears that the simplicity of this approximation makes it potentially useful for predicting homogeneous freezing temperatures of water droplets in the atmosphere.
International Nuclear Information System (INIS)
Highlights: • Electrochemical characterisation of ferroceneboronic acid-diol interactions in non-aqueous solutions. • Elucidation of the signalling process and signalling mechanism of the ferroceneboronic acid upon interaction with diols in aqueous and non-aqueous solutions. • Effect of coordination of boron atom on electrochemistry of ferroceneboronic acid in free and bound forms with diols. - Abstract: Ferroceneboronic acid (FcBA) was employed as a model compound for clarification of binding and signalling properties of molecular probe for saccharides. As the simplest electrochemically active boronic acid, its interactions with diverse diols were studied in homogeneous phase under aqueous and non-aqueous conditions. The FcBA-diol system was examined by cyclic voltammetry resulting in two redox pairs corresponding to free and bound forms of FcBA. Redox potential of the bound form of FcBA was shifted in the cathodic direction in aqueous conditions due to coordination of the hydroxyl group to the boron atom. Oppositely, the anodic shift of the redox potential was observed upon the interaction of FcBA with diols in non-aqueous solvents. The binding properties and signalling mechanism of electrochemically active boronic acids were deduced and the assumptions resulting from the electrochemical behaviour were confirmed by 1H and 11B NMR spectroscopies. The binding constants of the tested diols in aqueous and non-aqueous media were determined and compared
The chemical homogeneity of open clusters
Bovy, Jo
2015-01-01
Determining the level of chemical homogeneity in open clusters is of fundamental importance in the study of the evolution of star-forming clouds and that of the Galactic disk. Yet limiting the initial abundance spread in clusters has been hampered by difficulties in obtaining consistent spectroscopic abundances for different stellar types. Without reference to any specific model of stellar photospheres, a model for a homogeneous cluster is that it forms a one-dimensional sequence, with any differences between members due to variations in stellar mass and observational uncertainties. I present a novel method for investigating the abundance spread in open clusters that tests this one-dimensional hypothesis at the level of observed stellar spectra, rather than constraining homogeneity using derived abundances as traditionally done. Using high-resolution APOGEE spectra for 49 giants in M67, NGC 6819, and NGC 2420 I demonstrate that these spectra form one-dimensional sequences for each cluster. With detailed forwa...
Method of Mapping Anomalies in Homogenous Material
Woodard, Stanley E. (Inventor); Taylor, Bryant D. (Inventor)
2016-01-01
An electrical conductor and antenna are positioned in a fixed relationship to one another. Relative lateral movement is generated between the electrical conductor and a homogenous material while maintaining the electrical conductor at a fixed distance from the homogenous material. The antenna supplies a time-varying magnetic field that causes the electrical conductor to resonate and generate harmonic electric and magnetic field responses. Disruptions in at least one of the electric and magnetic field responses during this lateral movement are indicative of a lateral location of a subsurface anomaly. Next, relative out-of-plane movement is generated between the electrical conductor and the homogenous material in the vicinity of the anomaly's lateral location. Disruptions in at least one of the electric and magnetic field responses during this out-of-plane movement are indicative of a depth location of the subsurface anomaly. A recording of the disruptions provides a mapping of the anomaly.
Homogenization of Periodic Systems with Large Potentials
Allaire, Grégoire; Capdeboscq, Yves; Piatnitski, Andrey; Siess, Vincent; Vanninathan, M.
2004-11-01
We consider the homogenization of a system of second-order equations with a large potential in a periodic medium. Denoting by ɛ the period, the potential is scaled as ɛ-2. Under a generic assumption on the spectral properties of the associated cell problem, we prove that the solution can be approximately factorized as the product of a fast oscillating cell eigenfunction and of a slowly varying solution of a scalar second-order equation. This result applies to various types of equations such as parabolic, hyperbolic or eigenvalue problems, as well as fourth-order plate equation. We also prove that, for well-prepared initial data concentrating at the bottom of a Bloch band, the resulting homogenized tensor depends on the chosen Bloch band. Our method is based on a combination of classical homogenization techniques (two-scale convergence and suitable oscillating test functions) and of Bloch waves decomposition.
Commensurability effects in holographic homogeneous lattices
Andrade, Tomas
2015-01-01
An interesting application of the gauge/gravity duality to condensed matter physics is the description of a lattice via breaking translational invariance on the gravity side. By making use of global symmetries, it is possible to do so without scarifying homogeneity of the pertinent bulk solutions, which we thus term as "homogeneous holographic lattices." Due to their technical simplicity, these configurations have received a great deal of attention in the last few years and have been shown to correctly describe momentum relaxation and hence (finite) DC conductivities. However, it is not clear whether they are able to capture other lattice effects which are of interest in condensed matter. In this paper we investigate this question focusing our attention on the phenomenon of commensurability, which arises when the lattice scale is tuned to be equal to (an integer multiple of) another momentum scale in the system. We do so by studying the formation of spatially modulated phases in various models of homogeneous ...
Microscopic investigations of homogeneous nucleation in charged sphere suspensions.
Wette, Patrick; Schöpe, Hans Joachim; Palberg, Thomas
2005-11-01
We studied the homogeneous nucleation kinetics of an aqueous suspension of charged colloidal spheres under de-ionized conditions. Samples of equilibrium crystalline structure were shear molten and the metastable melt left to solidify after cessation of shear. At low particle number densities n, corresponding to low metastability of the melt, nucleation was monitored directly via video microscopy. We determined the nucleation rates gamma(t) by counting the number of newly appearing crystals in the observation volume per unit time. Using a suitable discrete adaptation of Avrami's [J. Chem. Phys. 7, 1003 (1939); ibid.8, 212 (1940); ibid.9, 177 (1941)] model for solidification via homogeneous nucleation and subsequent growth, we calculate the remaining free volume VF(t) to obtain the rate densities J(t) = gamma(t)/VF(t). We observe J(t) to rise steeply, display a plateau at a maximum rate density Jmax, and to decrease again. With increased n the plateau duration shrinks while Jmax increases. At low to moderate number densities fully solidified samples were analyzed by microscopy to obtain the grain-size distribution and the average crystallite size angle brackets(L). Under the assumption of stationarity, we obtained the nucleation rate density J(Avr), which increased strongly with increasing n. Interestingly, J(Avr) agrees quantitatively to Jmax and to J(Avr) as obtained previously from scattering data taken on the same sample at large n. Thus, by combination of different methods, reliable nucleation rate densities are now available over roughly one order of magnitude in n and eight orders of magnitude in J. PMID:16375564
Statistical methods for assessment of blend homogeneity
DEFF Research Database (Denmark)
Madsen, Camilla
2002-01-01
In this thesis the use of various statistical methods to address some of the problems related to assessment of the homogeneity of powder blends in tablet production is discussed. It is not straight forward to assess the homogeneity of a powder blend. The reason is partly that in bulk materials as...... shown how to set up parametric acceptance criteria for the batch that gives a high confidence that future samples with a probability larger than a specified value will pass the USP threeclass criteria. Properties and robustness of proposed changes to the USP test for content uniformity are investigated...
Homogenization of High-Contrast Brinkman Flows
Brown, Donald L.
2015-04-16
Modeling porous flow in complex media is a challenging problem. Not only is the problem inherently multiscale but, due to high contrast in permeability values, flow velocities may differ greatly throughout the medium. To avoid complicated interface conditions, the Brinkman model is often used for such flows [O. Iliev, R. Lazarov, and J. Willems, Multiscale Model. Simul., 9 (2011), pp. 1350--1372]. Instead of permeability variations and contrast being contained in the geometric media structure, this information is contained in a highly varying and high-contrast coefficient. In this work, we present two main contributions. First, we develop a novel homogenization procedure for the high-contrast Brinkman equations by constructing correctors and carefully estimating the residuals. Understanding the relationship between scales and contrast values is critical to obtaining useful estimates. Therefore, standard convergence-based homogenization techniques [G. A. Chechkin, A. L. Piatniski, and A. S. Shamev, Homogenization: Methods and Applications, Transl. Math. Monogr. 234, American Mathematical Society, Providence, RI, 2007, G. Allaire, SIAM J. Math. Anal., 23 (1992), pp. 1482--1518], although a powerful tool, are not applicable here. Our second point is that the Brinkman equations, in certain scaling regimes, are invariant under homogenization. Unlike in the case of Stokes-to-Darcy homogenization [D. Brown, P. Popov, and Y. Efendiev, GEM Int. J. Geomath., 2 (2011), pp. 281--305, E. Marusic-Paloka and A. Mikelic, Boll. Un. Mat. Ital. A (7), 10 (1996), pp. 661--671], the results presented here under certain velocity regimes yield a Brinkman-to-Brinkman upscaling that allows using a single software platform to compute on both microscales and macroscales. In this paper, we discuss the homogenized Brinkman equations. We derive auxiliary cell problems to build correctors and calculate effective coefficients for certain velocity regimes. Due to the boundary effects, we construct
An eigenelement method and two homogenization conditions
Institute of Scientific and Technical Information of China (English)
Yufeng Xing; Xingming Wang
2009-01-01
Under inspiration from the structure-preserving property of symplectic difference schemes for Hamiltonian systems, two homogenization conditions for a representa-tive unit cell of the periodical composites are proposed, one condition is the equivalence of strain energy, and the other is the deformation similarity. Based on these two homoge-nization conditions, an eigenelement method is presented, which is characteristic of structure-preserving property. It follows from the frequency comparisons that the eigenel-ement method is more accurate than the stiffness average method and the compliance average method.
Irregular Homogeneity Domains in Ternary Intermetallic Systems
Jean-Marc Joubert; Mohamed Andasmas; Jean-Claude Crivello
2015-01-01
Ternary intermetallic A–B–C systems sometimes have unexpected behaviors. The present paper examines situations in which there is a tendency to simultaneously form the compounds ABx, ACx and BCx with the same crystal structure. This causes irregular shapes of the phase homogeneity domains and, from a structural point of view, a complete reversal of site occupancies for the B atom when crossing the homogeneity domain. This work reviews previous studies done in the systems Fe–Nb–Zr, Hf–Mo–Re, Hf...
Homogeneous oxalate precipitation of Pu(III)
International Nuclear Information System (INIS)
This paper reports on homogeneous oxalate precipitation using diethyl oxalate which was compared to precipitating Pu(III) oxalate with solid oxalic acid. The diethyl oxalate technique at 75 degrees C is better because it gives 50% less plutonium in the filtrate with a reasonable filtering time. Also, the procedure for the homogeneous precipitation is easier to automate because the liquid diethyl oxalate is simpler to introduce into the precipitator than solid oxalic acid. It also provides flexibility because the hydrolysis rate and therefore the precipitation rate can be controlled by varying the temperature
Hyperelastic bodies under homogeneous Cauchy stress induced by non-homogeneous finite deformations
Mihai, L Angela
2016-01-01
We discuss whether homogeneous Cauchy stress implies homogeneous strain in isotropic nonlinear elasticity. While for linear elasticity the positive answer is clear, we exhibit, through detailed calculations, an example with inhomogeneous continuous deformation but constant Cauchy stress. The example is derived from a non rank-one convex elastic energy. Connections to conforming and non-conforming finite element implementations are drawn.
International Nuclear Information System (INIS)
The chemistry of iodine has been examined in aqueous solutions of pH 6 to 10 containing 2500 ppM boron as H3BO3 at temperatures up to 1500C using absorption spectrophotometry to identify and monitor the iodine species present. Kinetic rate constants for the disproportionation of the HOI intermediate, 3HOI= IO3- + 2I- + 3H+, have been measured as a function of pH even though no direct spectral evidence for HOI itself has been observed. An HOI partition coefficient >104 has been estimated; results of ionic strength tests are consistent with HOI being present as an uncharged triatomic species in solution. Redox and radiation effects on the aqueous iodine chemistry have also been described. 11 refs., 2 figs., 3 tabs
Benchmarking homogenization algorithms for monthly data
Czech Academy of Sciences Publication Activity Database
Venema, V. K. C.; Mestre, O.; Aquilar, E.; Auer, I.; Guijarro, J. A.; Domonkos, P.; Vertačník, G.; Szentimrey, T.; Štěpánek, Petr; Zahradníček, Pavel; Viarre, J.; Mueller-Westermeier, G.; Lakatos, M.; Williams, C. N.; Menne, M. J.; Lindau, R.; Rasol, D.; Rustemeier, E.; Kolokythas, K.; Marinova, T.; Andresen, L.; Acquaotta, F.; Fratianni, S.; Cheval, S.; Klancar, M.; Brunetti, M.; Gruber, C.; Duran, M. P.; Likso, T.; Esteban, P.; Brandsma, T.
2012-01-01
Roč. 8, č. 1 (2012), s. 89-115. ISSN 1814-9324 Institutional support: RVO:67179843 Keywords : climate data * instrumental time-series * greater alpine region * homogeneity test * variability * inhomogeneities Subject RIV: EH - Ecology, Behaviour Impact factor: 3.556, year: 2012
Volume and geometry of homogeneously adequate knots
Bartholomew, Paige; McQuarrie, Shane; Purcell, Jessica S.; Weser, Kai
2014-01-01
We bound the hyperbolic volumes of a large class of knots and links, called homogeneously adequate knots and links, in terms of their diagrams. To do so, we use the decomposition of these links into ideal polyhedra, developed by Futer, Kalfagianni, and Purcell. We identify essential product disks in these polyhedra.
String pair production in non homogeneous backgrounds
Bolognesi, Stefano; Tallarita, Gianni
2016-01-01
We consider string pair production in non homogeneous electric backgrounds. We study several particular configurations which can be addressed with the Euclidean world-sheet instanton technique, the analogue of the world-line instanton for particles. In the first case the string is suspended between two D-branes in flat space-time, in the second case the string lives in AdS and terminates on one D-brane (this realizes the holographic Schwinger effect). In some regions of parameter space the result is well approximated by the known analytical formulas, either the particle pair production in non-homogeneous background or the string pair production in homogeneous background. In other cases we see effects which are intrinsically stringy and related to the non-homogeneity of the background. The pair production is enhanced already for particles in time dependent electric field backgrounds. The string nature enhances this even further. For spacial varying electrical background fields the string pair production is les...
Price Elasticities Implied by Homogeneous Production Functions
Price, J. Michael
1994-01-01
If a production process is characterized by a homogeneous production function, the conditions required for profit maximization imply that the elasticity of demand for each input must be elastic with respect to output price. This restriction limits the usefulness of these functions in empirical analysis.
Quantum Homogeneous Spaces as Quantum Quotient Spaces
Brzezinski, Tomasz
1995-01-01
We show that certain embeddable homogeneous spaces of a quantum group that do not correspond to a quantum subgroup still have the structure of quantum quotient spaces. We propose a construction of quantum fibre bundles on such spaces. The quantum plane and the general quantum two-spheres are discussed in detail.
Inverse acoustic problem of N homogeneous scatterers
DEFF Research Database (Denmark)
Berntsen, Svend
The three-dimensional inverse acoustic medium problem of N homogeneous objects with known geometry and location is considered. It is proven that one scattering experiment is sufficient for the unique determination of the complex wavenumbers of the objects. The mapping from the scattered fields at a...
Hypersurface homogeneous Killing spinor space–times
International Nuclear Information System (INIS)
I present a complete list of hypersurface homogeneous space–times admitting a non-null valence two Killing spinor, including a new class admitting only exceptional Killing tensors. A connection is established with the classification of locally rotationally symmetric or boost symmetric space–times. (paper)
Homogeneity analysis of precipitation series in Iran
Hosseinzadeh Talaee, P.; Kouchakzadeh, Mahdi; Shifteh Some'e, B.
2014-10-01
Assessment of the reliability and quality of historical precipitation data is required in the modeling of hydrology and water resource processes and for climate change studies. The homogeneity of the annual and monthly precipitation data sets throughout Iran was tested using the Bayesian, Cumulative Deviations, and von Neumann tests at a significance level of 0.05. The precipitation records from 41 meteorological stations covering the years between 1966 and 2005 were considered. The annual series of Iranian precipitation were found to be homogeneous by applying the Bayesian and Cumulative Deviations tests, while the von Neumann test detected inhomogeneities at seven stations. Almost all the monthly precipitation data sets are homogeneous and considered as "useful." The outputs of the statistical tests for the homogeneity analysis of the precipitation time series had discrepancies in some cases which are related to different sensitivities of the tests to break in the time series. It was found that the von Neumann test is more sensitive than the Bayesian and Cumulative Deviations tests in the determination of inhomogeneity in the precipitation series.
Locally periodic homogenization of reflected diffusion
Directory of Open Access Journals (Sweden)
Aboubakary Diakhaby
2006-01-01
Full Text Available We study the homogenization of reflected SDEs with locally periodic coefficients and highly oscillating drift. Our method is entirely probabilistic, and builds upon earlier works of Tanaka, Benchérif-Madani and Pardoux, and Bensoussan et al We extend, to Tanaka's theorem locally periodic case.
Homogeneous protein analysis by magnetic core-shell nanorod probes
Schrittwieser, Stefan
2016-03-29
Studying protein interactions is of vital importance both to fundamental biology research and to medical applications. Here, we report on the experimental proof of a universally applicable label-free homogeneous platform for rapid protein analysis. It is based on optically detecting changes in the rotational dynamics of magnetically agitated core-shell nanorods upon their specific interaction with proteins. By adjusting the excitation frequency, we are able to optimize the measurement signal for each analyte protein size. In addition, due to the locking of the optical signal to the magnetic excitation frequency, background signals are suppressed, thus allowing exclusive studies of processes at the nanoprobe surface only. We study target proteins (soluble domain of the human epidermal growth factor receptor 2 - sHER2) specifically binding to antibodies (trastuzumab) immobilized on the surface of our nanoprobes and demonstrate direct deduction of their respective sizes. Additionally, we examine the dependence of our measurement signal on the concentration of the analyte protein, and deduce a minimally detectable sHER2 concentration of 440 pM. For our homogeneous measurement platform, good dispersion stability of the applied nanoprobes under physiological conditions is of vital importance. To that end, we support our measurement data by theoretical modeling of the total particle-particle interaction energies. The successful implementation of our platform offers scope for applications in biomarker-based diagnostics as well as for answering basic biology questions.
Photodegradation of Lincomycin in Aqueous Solution
Directory of Open Access Journals (Sweden)
2006-01-01
Full Text Available Aqueous solutions of lincomycin were irradiated with UV light in homogeneous and heterogeneous systems. Lincomycin disappeared in both systems but the presence of TiO 2 noticeably accelerated the degradation of the antibiotic in comparison with direct photolysis. The rate of decomposition was dependent on the concentration of lincomycin and followed a pseudo-first-order kinetics. Photolysis involved only the oxidation of lincomycin without mineralization. Differently, the treatment with TiO 2 and UV light resulted in a complete mineralization of the antibiotic. The degradation pathways involved S- and N-demethylation and propyldealkylation. The mineralization of the molecule led to the formation of sulfate, ammonium, and nitrate ions.
Aqueous sodium hydroxide seasonal thermal energy storage
Energy Technology Data Exchange (ETDEWEB)
Gantenbein, P.; Daguenet-Frick, X.; Frank, E. [Univ. of Applied Sciences Rapperswil (Switzerland). Inst. for Solar Technologies SPF; Weber, R.; Fumey, B. [EMPA Swiss Federal Laboratories for Materials Science and Technology, Duebendorf (Switzerland); Williamson, T. [Kingspan Renewables Ltd, Portadown, Co. Armagh, Northern Ireland (United Kingdom)
2012-07-01
Seasonal storage of sensible thermal energy in materials is a challenge in respect to thermal loss corresponding to low volumetric energy density. In a process involving absorption and desorption lower heat losses and higher energy densities can be reached. The working pair sodium hydroxide (NaOH) and water can be employed to this purpose. A possible application of such a system can be a single family passive energy building that requires a maximum power output of approximately 8 kW. The required absorption/desorption zone can be designed as a falling film tube bundle, using either Hu's or Owens' correlations. To meet the required power the tube bundle can be built of 300 mm long tubes with an outer diameter of 12 mm in a configuration of either 3 rows of 18 tubes or 2 rows of 25 tubes. During desorption one row of 18 tubes or 3 rows of 6 tubes are sufficient. In the absorption or discharging process a mass flow of 2 to 4 kg/h of aqueous NaOH with a concentration of 50 wt% NaOH is required. In the reverse process 18 to 30 kg/h of aqueous NaOH at a concentration of 30 wt% are necessary. The mass transport is performed without recirculation, reducing the parasitic power consumption. Initial experiments conducted with a less reactive substitute liquid showed good homogeneous distribution.
Bacterial Acclimation Inside an Aqueous Battery.
Directory of Open Access Journals (Sweden)
Dexian Dong
Full Text Available Specific environmental stresses may lead to induced genomic instability in bacteria, generating beneficial mutants and potentially accelerating the breeding of industrial microorganisms. The environmental stresses inside the aqueous battery may be derived from such conditions as ion shuttle, pH gradient, free radical reaction and electric field. In most industrial and medical applications, electric fields and direct currents are used to kill bacteria and yeast. However, the present study focused on increasing bacterial survival inside an operating battery. Using a bacterial acclimation strategy, both Escherichia coli and Bacillus subtilis were acclimated for 10 battery operation cycles and survived in the battery for over 3 days. The acclimated bacteria changed in cell shape, growth rate and colony color. Further analysis indicated that electrolyte concentration could be one of the major factors determining bacterial survival inside an aqueous battery. The acclimation process significantly improved the viability of both bacteria E. coli and B. subtilis. The viability of acclimated strains was not affected under battery cycle conditions of 0.18-0.80 mA cm(-2 and 1.4-2.1 V. Bacterial addition within 1.0×10(10 cells mL(-1 did not significantly affect battery performance. Because the environmental stress inside the aqueous battery is specific, the use of this battery acclimation strategy may be of great potential for the breeding of industrial microorganisms.
A unidirectional acoustic cloak for multilayered background media with homogeneous metamaterials
Zhu, Jian; Chen, Tianning; Liang, Qingxuan; Wang, Xiaopeng; Xiong, Jie; Jiang, Ping
2015-08-01
The acoustic cloak, which can make an object hard to detect acoustically in a homogeneous background, has attracted great attention from researchers in recent years. The inhomogeneous background media were considered in this paper. The relative constitutive parameters were derived for acoustic cloaks working in multilayered media. And a unidirectional acoustic cloak for layered background media was proposed, designed and implemented successfully in a wide frequency range. In water and NaCl aqueous solution, the acoustic cloak was designed and realized with homogeneous metamaterials which were composed of steel and porous materials. The effective parameters of the unit cells of the cloak were determined by using the effective medium theory. Numerical results demonstrated excellent cloaking performance and showed that such a device could be physically realized with natural materials which will greatly promote the real applications of an invisibility cloak in inhomogeneous backgrounds.
A unidirectional acoustic cloak for multilayered background media with homogeneous metamaterials
International Nuclear Information System (INIS)
The acoustic cloak, which can make an object hard to detect acoustically in a homogeneous background, has attracted great attention from researchers in recent years. The inhomogeneous background media were considered in this paper. The relative constitutive parameters were derived for acoustic cloaks working in multilayered media. And a unidirectional acoustic cloak for layered background media was proposed, designed and implemented successfully in a wide frequency range. In water and NaCl aqueous solution, the acoustic cloak was designed and realized with homogeneous metamaterials which were composed of steel and porous materials. The effective parameters of the unit cells of the cloak were determined by using the effective medium theory. Numerical results demonstrated excellent cloaking performance and showed that such a device could be physically realized with natural materials which will greatly promote the real applications of an invisibility cloak in inhomogeneous backgrounds. (paper)
Homogeneous and Heterogeneous (Fex, Cr1-x)(OH)3 Precipitation: Implications for Cr Sequestration.
Dai, Chong; Zuo, Xiaobing; Cao, Bo; Hu, Yandi
2016-02-16
The formation of (Fe, Cr)(OH)3 nanoparticles determines the fate of aqueous Cr in many aquatic environments. Using small-angle X-ray scattering, precipitation rates of (Fe, Cr)(OH)3 nanoparticles in solution and on quartz were quantified from 0.1 mM Fe(III) solutions containing 0-0.25 mM Cr(III) at pH = 3.7 ± 0.2. Concentration ratio of aqueous Cr(III)/Fe(III) controlled the chemical composition (x) of (Fex, Cr1-x)(OH)3 precipitates, solutions' supersaturation with respect to precipitates, and the surface charge of quartz. Therefore, the aqueous Cr(III)/Fe(III) ratio affected homogeneous (in solution) and heterogeneous (on quartz) precipitation rates of (Fex, Cr1-x)(OH)3 through different mechanisms. The sequestration mechanisms of Cr(III) in precipitates were also investigated. In solutions with high aqueous Cr(III)/Fe(III) ratios, surface enrichment of Cr(III) on the precipitates occurred, resulting in slower particle growth in solutions. From solutions with 0-0.1 mM Cr(III), the particles on quartz grew from 2 to 4 nm within 1 h. Interestingly, from solution with 0.25 mM Cr(III), particles of two distinct sizes (2 and 6 nm) formed on quartz, and their sizes remained unchanged throughout the reaction. Our study provided new insights on homogeneous and heterogeneous precipitation of (Fex, Cr1-x)(OH)3 nanoparticles, which can help determine the fate of Cr in aquatic environments. PMID:26765070
Homogeneous and Heterogeneous (Fex, Cr1-x)(OH)3 Precipitation: Implications for Cr Sequestration
Energy Technology Data Exchange (ETDEWEB)
Dai, Chong; Zuo, Xiaobing; Cao, B; Hu, Yandi
2016-02-16
The formation of (Fe, Cr)(OH)3 nanoparticles determines the fate of aqueous Cr in many aquatic environments. Using small angle X-ray scattering, precipitation rates of (Fe, Cr)(OH)3 nanoparticles in solution and on quartz were quantified from 0.1 mM Fe(III) solutions containing 0 – 0.25 mM Cr(III) at pH = 3.7 ± 0.2. Concentration ratio of aqueous Cr(III)/Fe(III) controlled the chemical composition (x) of (Fex, Cr1-x)(OH)3 precipitates, solutions’ supersaturation with respect to precipitates, and the surface charge of quartz. Therefore, aqueous Cr(III)/Fe(III) ratio affected homogeneous (in solution) and heterogeneous (on quartz) precipitation rates of (Fex, Cr1-x)(OH)3 through different mechanisms. The sequestration mechanisms of Cr(III) in precipitates were also investigated. In solutions with high aqueous Cr(III)/Fe(III) ratios, surface enrichment of Cr(III) on the precipitates occurred, resulting in slower particle growth in solution. From solutions with 0 – 0.1 mM Cr(III), the particles on quartz grew from 2 to 4 nm within 1 h. Interestingly, from solution with 0.25 mM Cr(III), particles of two distinct sizes (2 and 6 nm) formed on quartz, and their sizes remained unchanged throughout the reaction. Our study provided new insights on homogeneous and heterogeneous precipitation of (Fex, Cr1-x)(OH)3 nanoparticles, which can help determine the fate of Cr in aquatic environments.
Shape optimization in biomimetics by homogenization modelling
International Nuclear Information System (INIS)
Optimal shape design of microstructured materials has recently attracted a great deal of attention in material science. The shape and the topology of the microstructure have a significant impact on the macroscopic properties. The present work is devoted to the shape optimization of new biomorphic microcellular ceramics produced from natural wood by biotemplating. We are interested in finding the best material-and-shape combination in order to achieve the optimal prespecified performance of the composite material. The computation of the effective material properties is carried out using the homogenization method. Adaptive mesh-refinement technique based on the computation of recovered stresses is applied in the microstructure to find the homogenized elasticity coefficients. Numerical results show the reliability of the implemented a posteriori error estimator. (author)
Is the Universe Homogeneous? (On Large Scales)
Guzzo, L
1997-01-01
I critically discuss in a pedagogical and phenomenological way a few crucial tests challenging the claims by Pietronero and collaborators that there is no evidence from available galaxy catalogues that the Universe is actually homogeneous above a certain scale. In a series of papers, these authors assert that observations are consistent with a fractal distribution of objects extending to the limit of the present data. I show that while galaxies are indeed clustered in a scale-free way on small and intermediate scales, this behaviour does not continue indefinitely. Although the specific wavelength at which the galaxy distribution apparently turns to homogeneity is dangerously close to the size of the largest samples presently available, there are serious hints suggesting that this turnover is real and that its effects are detected in the behaviour of statistical estimators. The most recent claims of a continuing fractal hierarchy up to scales of several hundreds Mpc seem to be abscribable to the use of incompl...
Searching for the scale of homogeneity
Martínez, V J; Moyeed, R A; Graham, M J; Martinez, Vicent J.; Pons-Borderia, Maria-Jesus; Moyeed, Rana A.; Graham, Matthew J.
1998-01-01
We introduce a statistical quantity, known as the $K$ function, related to the integral of the two--point correlation function. It gives us straightforward information about the scale where clustering dominates and the scale at which homogeneity is reached. We evaluate the correlation dimension, $D_2$, as the local slope of the log--log plot of the $K$ function. We apply this statistic to several stochastic point fields, to three numerical simulations describing the distribution of clusters and finally to real galaxy redshift surveys. Four different galaxy catalogues have been analysed using this technique: the Center for Astrophysics I, the Perseus--Pisces redshift surveys (these two lying in our local neighbourhood), the Stromlo--APM and the 1.2 Jy {\\it IRAS} redshift surveys (these two encompassing a larger volume). In all cases, this cumulant quantity shows the fingerprint of the transition to homogeneity. The reliability of the estimates is clearly demonstrated by the results from controllable point sets...
Quantum memory with a controlled homogeneous splitting
International Nuclear Information System (INIS)
We propose a quantum memory protocol where an input light field can be stored onto and released from a single ground state atomic ensemble by controlling dynamically the strength of an external static and homogeneous field. The technique relies on the adiabatic following of a polaritonic excitation onto a state for which the forward collective radiative emission is forbidden. The resemblance with the archetypal electromagnetically induced transparency is only formal because no ground state coherence-based slow-light propagation is considered here. As compared to the other grand category of protocols derived from the photon-echo technique, our approach only involves a homogeneous static field. We discuss two physical situations where the effect can be observed, and show that in the limit where the excited state lifetime is longer than the storage time; the protocols are perfectly efficient and noise free. We compare the technique with other quantum memories, and propose atomic systems where the experiment can be realized. (paper)
Smooth homogeneous structures in operator theory
Beltita, Daniel
2005-01-01
Geometric ideas and techniques play an important role in operator theory and the theory of operator algebras. Smooth Homogeneous Structures in Operator Theory builds the background needed to understand this circle of ideas and reports on recent developments in this fruitful field of research. Requiring only a moderate familiarity with functional analysis and general topology, the author begins with an introduction to infinite dimensional Lie theory with emphasis on the relationship between Lie groups and Lie algebras. A detailed examination of smooth homogeneous spaces follows. This study is illustrated by familiar examples from operator theory and develops methods that allow endowing such spaces with structures of complex manifolds. The final section of the book explores equivariant monotone operators and Kähler structures. It examines certain symmetry properties of abstract reproducing kernels and arrives at a very general version of the construction of restricted Grassmann manifolds from the theory of loo...
Beyond relationships between homogeneous and heterogeneous catalysis
Energy Technology Data Exchange (ETDEWEB)
Dixon, David A. [Univ. of Alabama, Tuscaloosa, AL (United States); Katz, Alexander [Univ. of California, Berkeley, CA (United States); Arslan, Ilke [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gates, Bruce C. [Univ. of California, Davis, CA (United States)
2014-08-13
Scientists who regard catalysis as a coherent field have been striving for decades to articulate the fundamental unifying principles. But because these principles seem to be broader than chemistry, chemical engineering, and materials science combined, catalytic scientists commonly interact within the sub-domains of homogeneous, heterogeneous, and bio-catalysis, and increasingly within even narrower domains such as organocatalysis, phase-transfer catalysis, acid-base catalysis, zeolite catalysis, etc. Attempts to unify catalysis have motivated researchers to find relationships between homogeneous and heterogeneous catalysis and to mimic enzymes. These themes have inspired vibrant international meetings and workshops, and we have benefited from the idea exchanges and have some thoughts about a path forward.
Broken Ergodicity in Ideal, Homogeneous, Incompressible Turbulence
Morin, Lee; Shebalin, John; Fu, Terry; Nguyen, Phu; Shum, Victor
2010-01-01
We discuss the statistical mechanics of numerical models of ideal homogeneous, incompressible turbulence and their relevance for dissipative fluids and magnetofluids. These numerical models are based on Fourier series and the relevant statistical theory predicts that Fourier coefficients of fluid velocity and magnetic fields (if present) are zero-mean random variables. However, numerical simulations clearly show that certain coefficients have a non-zero mean value that can be very large compared to the associated standard deviation. We explain this phenomena in terms of broken ergodicity', which is defined to occur when dynamical behavior does not match ensemble predictions on very long time-scales. We review the theoretical basis of broken ergodicity, apply it to 2-D and 3-D fluid and magnetohydrodynamic simulations of homogeneous turbulence, and show new results from simulations using GPU (graphical processing unit) computers.
Kinematical uniqueness of homogeneous isotropic LQC
Engle, Jonathan
2016-01-01
In a paper by Ashtekar and Campiglia, invariance under volume preserving residual diffeomorphisms has been used to single out the standard representation of the reduced holonomy-flux algebra in homogeneous loop quantum cosmology (LQC). In this paper, we use invariance under all residual diffeomorphisms to single out the standard kinematical Hilbert space of homogeneous isotropic LQC for both the standard configuration space $\\mathbb{R}_{\\mathrm{Bohr}}$, as well as for the Fleischhack one $\\mathbb{R} \\sqcup \\mathbb{R}_{\\mathrm{Bohr}}$. We first determine the scale invariant Radon measures on these spaces, and then show that the Haar measure on $\\mathbb{R}_{\\mathrm{Bohr}}$ is the only such measure for which the momentum operator is hermitian w.r.t. the corresponding inner product. In particular, the measure is forced to be identically zero on $\\mathbb{R}$ in the Fleischhack case, so that for both approaches, the standard kinematical LQC-Hilbert space is singled out.
Resonant ultrasound spectroscopy and homogeneity in polycrystals.
Kaplan, Gunes; Darling, T W; McCall, K R
2009-01-01
Resonant ultrasound spectroscopy (RUS) is capable of determining the bulk elastic properties of a solid from its characteristic vibration frequencies, given the dimensions, density and shape of the sample. The model used for extracting values of the elastic constants assumes perfect homogeneity, which can be approximated by average-isotropic polycrystals. This approximation is excellent in the small grain regime assumed for most averaging procedures, but for real samples with indeterminate grain size distributions, it is not clear where the approximation breaks down. RUS measurements were made on pure copper samples where the grain size distribution was changed by progressive heat treatments in order to find a quantitative limit for the loss of homogeneity. It is found that when a measure of the largest grains is 15% of the sample's smallest dimension, the deviation in RUS fits indicates elastic inhomogeneity. PMID:18804831
Homogenization of biomechanical models for plant tissues
Piatnitski, Andrey; Ptashnyk, Mariya
2015-01-01
In this paper homogenization of a mathematical model for plant tissue biomechanics is presented. The microscopic model constitutes a strongly coupled system of reaction-diffusion-convection equations for chemical processes in plant cells, the equations of poroelasticity for elastic deformations of plant cell walls and middle lamella, and Stokes equations for fluid flow inside the cells. The chemical process in cells and the elastic properties of cell walls and middle lamella are coupled becau...
Explaining Price Dispersion for Homogeneous Grocery Products
Aalto-Setälä Ville
2003-01-01
This study examines the dispersion in prices for homogeneous grocery products, and studies the effect of product characteristics, demographic characteristics of consumers, and market structure on search costs and price dispersion. The findings show that price dispersion is affected by search costs. The variables that increased relative price dispersion the most were low budget share and low price of the product. Demographic characteristics affected price dispersion as well: a high proportion ...
Higher dimensional homogeneous cosmology in Lyra geometry
Indian Academy of Sciences (India)
F Rahaman; S Das; N Begum; M Hossain
2003-07-01
Assuming a homogeneous perfect ﬂuid with ρ = ρ() and = (), we have obtained exact solutions for cosmological models in higher-dimension based on Lyra geometry. Depending on the form of metric chosen, the model is similar to FRW type. The explicit solutions of the scale factor are found via the assumption of an equation of state = ρ, where is a constant. Some astrophysical parameters are also calculated.
Algebraic density property of homogeneous spaces
Donzelli, Fabrizio; Dvorsky, Alexander; Kaliman, Shulim
2008-01-01
Let $X$ be an affine algebraic variety with a transitive action of the algebraic automorphism group. Suppose that $X$ is equipped with several non-degenerate fixed point free $SL_2$-actions satisfying some mild additional assumption. Then we show that the Lie algebra generated by completely integrable algebraic vector fields on $X$ coincides with the set of all algebraic vector fields. In particular, we show that apart from a few exceptions this fact is true for any homogeneous space of form ...
Spherical cloaking with homogeneous isotropic multilayered structures.
Qiu, Cheng-Wei; Hu, Li; Xu, Xiaofei; Feng, Yijun
2009-04-01
We propose a practical realization of electromagnetic spherical cloaking by layered structure of homogeneous isotropic materials. By mimicking the classic anisotropic cloak by many alternating thin layers of isotropic dielectrics, the permittivity and permeability in each isotropic layer can be properly determined by effective medium theory in order to achieve invisibility. The model greatly facilitates modeling by Mie theory and realization by multilayer coating of dielectrics. Eigenmode analysis is also presented to provide insights of the discretization in multilayers. PMID:19518392
Homogenization of eigenvalue problems in perforated domains
Vanninathan, M.
1981-01-01
In this paper, we treat some eigenvalue problems in periodically perforated domains and study the asymptotic behaviour of the eigenvalues and the eigenvectors when the number of holes in the domain increases to infinity Using the method of asymptotic expansion, we give explicit formula for the homogenized coefficients and expansion for eigenvalues and eigenvectors. If we denote by ε the size of each hole in the domain, then we obtain the following aysmptotic expansion for the eigenvalues: Dir...
A Statistical Theory of Homogeneous Isotropic Turbulence
de Divitiis, Nicola
2009-01-01
The present work proposes a theory of isotropic and homogeneous turbulence for incompressible fluids, which assumes that the turbulence is due to the bifurcations associated to the velocity field. The theory is formulated using a representation of the fluid motion which is more general than the classical Navier-Stokes equations, where the fluid state variables are expressed in terms of the referential coordinates. The theory is developed according to the following four items: 1) Study of the ...
Emergence of Leadership within a Homogeneous Group
Eskridge, Brent E.; Valle, Elizabeth; Schlupp, Ingo
2015-01-01
Large scale coordination without dominant, consistent leadership is frequent in nature. How individuals emerge from within the group as leaders, however transitory this position may be, has become an increasingly common question asked. This question is further complicated by the fact that in many of these aggregations, differences between individuals are minor and the group is largely considered to be homogeneous. In the simulations presented here, we investigate the emergence of leadership i...
Spin precession in a homogeneous gravitational field
International Nuclear Information System (INIS)
First a geometrical approach for the homogeneous gravitational field is given, emphasizing its main physical features, and in accordance with relativity in which this field is interpreted as the field apparently experienced by a uniformly accelerated observer (Born-Motion). A stationary beam of particles is then studied in both the particle and the wave pictures. In the particle picture, we first study the beam in the non-relativistic approximation, and then the relativistic beam. The velocity fields, and orbit equations, as well as the connection of the relativistic beam to the non-relativistic beam, as c→ infinity, are given. Our main result is then established by calculating the so-called Quasi-Thomas precession of the spin of the particle in a homogeneous gravitational field. The differences with the regular Thomas precession are discussed and illustrated with space-time diagrams. Some numerical estimates are given. The beam is then studied in the wave picture for Dirac particles. First the Dirac equation is established in the homogeneous gravitational field by the appropriate coordinate, and Lorentz transformation, on the Dirac 4-component spinor wave function in the freely falling frame. Then working to first order in the coupling constant g, an approximate plane wave function is given as a solution for the stationary beam. The precession of the spin is then obtained, and it agrees with the result given by the particle picture. The translationary motion is also discussed briefly. The similar problem of a homogeneous electric field is discussed, via the principle of equivalence, and some formal analogies are found. Finally, a brief discussion of future research, in connection with recently available experiments to test the principle of equilavence at the quantum level, and in the context of this thesis, is given
General description of homogeneous isotropic disordered systems
Averbuch, Pierre
1993-01-01
As all the physical quantities describing such a system are spherical tensors, it is shown that homogeneity and isotropy imply for the cross-correlation functions such conditions that they can be written with only standard spherical functions and a few scalar functions in which the whole physical information is included. The two limiting cases of a system with many independent defects and of a polycrystal, Gauss and Poisson limits, are discussed.
'Parodie', a large homogeneous stationary plasma
International Nuclear Information System (INIS)
A low pressure discharge plasma with magnetic multipolar confinement has been constructed to experimentally investigate turbulence phenomena. Its main characteristics are described: the technology (cylindrical machine 1 m in diameter and 1 m long, sliding vacuum rule section, permanent magnets...); and the plasma parameters (108-1010 cm-3 electron density; homogeneous within 1% in a volume of 0.3 m3, fluctuations at thermal level)
Correlated equilibria in homogenous good Bertrand competition
DEFF Research Database (Denmark)
Jann, Ole; Schottmüller, Christoph
2015-01-01
We show that there is a unique correlated equilibrium, identical to the unique Nash equilibrium, in the classic Bertrand oligopoly model with homogenous goods and identical marginal costs. This provides a theoretical underpinning for the so-called "Bertrand paradox'' as well as its most general f...... formulation to date. Our proof generalizes to asymmetric marginal costs and arbitrarily many players in the following way: The market price cannot be higher than the second lowest marginal cost in any correlated equilibrium....
Diffusion homogenization in multicomponent dispersed heterogeneous systems
International Nuclear Information System (INIS)
The processes of diffusion homogenizing in multicomponent powders within the temperature range of solid solutions are under study. The physical model is suggested and the mathematical algorithm is developed to calculate the statistical distribution function in the concentration space as well as other integral values describing the degree of system heterogeneity. Numerical solution is made for ternary metal system (W-Mo-Re) in the form of computer program. Calculation results are presented
... and authentic illustrations used in the publication of medical books, journals, films, videotapes, exhibits, posters, wall charts, and computer programs. A medical illustrator may also work as a member of ...
DEFF Research Database (Denmark)
Musaeus, Peter
2015-01-01
Purpose: To examine philosophical stances underpinning medical identity and assess the conceptual relationship between physician, medical practice and culture. Argument: Medical identity is about the ideals and moral positions that physicians take when justifying themselves. Medical identity is the...... hedonistic versus sentimentalist approaches to medical identity. The sociocultural philosophical analysis of medical identity can shed light on what it means conceptually for a physician to harbor beliefs associated with him/her being taken to be an autonomous professional. It is important because it touches...... on the meaning of being a compassionate, good and skilled physician, making its relevance to person-centered medicine self-evident. Conclusion: Medical identity should be analyzed with reference to literature, philosophy and medical practice in order for the physician to exercise a reflective...
... email share facebook twitter google plus linkedin Medical Management Although there’s no cure for CMT, there are ... individualized physical therapy program. For more on medical management of CMT, see Surgery Sometimes, Bracing Often, Caution ...
Equilibrium states of homogeneous sheared compressible turbulence
Directory of Open Access Journals (Sweden)
M. Riahi
2011-06-01
Full Text Available Equilibrium states of homogeneous compressible turbulence subjected to rapid shear is studied using rapid distortion theory (RDT. The purpose of this study is to determine the numerical solutions of unsteady linearized equations governing double correlations spectra evolution. In this work, RDT code developed by authors solves these equations for compressible homogeneous shear flows. Numerical integration of these equations is carried out using a second-order simple and accurate scheme. The two Mach numbers relevant to homogeneous shear flow are the turbulent Mach number Mt, given by the root mean square turbulent velocity fluctuations divided by the speed of sound, and the gradient Mach number Mg which is the mean shear rate times the transverse integral scale of the turbulence divided by the speed of sound. Validation of this code is performed by comparing RDT results with direct numerical simulation (DNS of [A. Simone, G.N. Coleman, and C. Cambon, Fluid Mech. 330, 307 (1997] and [S. Sarkar, J. Fluid Mech. 282, 163 (1995] for various values of initial gradient Mach number Mg0. It was found that RDT is valid for small values of the non-dimensional times St (St 10 in particular for large values of Mg0. This essential feature justifies the resort to RDT in order to determine equilibrium states in the compressible regime.
Homogeneous Biosensing Based on Magnetic Particle Labels
Schrittwieser, Stefan
2016-06-06
The growing availability of biomarker panels for molecular diagnostics is leading to an increasing need for fast and sensitive biosensing technologies that are applicable to point-of-care testing. In that regard, homogeneous measurement principles are especially relevant as they usually do not require extensive sample preparation procedures, thus reducing the total analysis time and maximizing ease-of-use. In this review, we focus on homogeneous biosensors for the in vitro detection of biomarkers. Within this broad range of biosensors, we concentrate on methods that apply magnetic particle labels. The advantage of such methods lies in the added possibility to manipulate the particle labels by applied magnetic fields, which can be exploited, for example, to decrease incubation times or to enhance the signal-to-noise-ratio of the measurement signal by applying frequency-selective detection. In our review, we discriminate the corresponding methods based on the nature of the acquired measurement signal, which can either be based on magnetic or optical detection. The underlying measurement principles of the different techniques are discussed, and biosensing examples for all techniques are reported, thereby demonstrating the broad applicability of homogeneous in vitro biosensing based on magnetic particle label actuation.
Tits Satake projections of homogeneous special geometries
Fré, Pietro; Gargiulo, Floriana; Rosseel, Jan; Rulik, Ksenya; Trigiante, Mario; Van Proeyen, Antoine
2007-01-01
We organize the homogeneous special geometries, describing as well the couplings of D = 6, 5, 4 and 3 supergravities with eight supercharges, in a small number of universality classes. This relates manifolds on which similar types of dynamical solutions can exist. The mathematical ingredient is the Tits Satake projection of real simple Lie algebras, which we extend to all solvable Lie algebras occurring in these homogeneous special geometries. Apart from some exotic cases all the other, 'very special', homogeneous manifolds can be grouped into seven universality classes. The organization of these classes, which capture the essential features of their basic dynamics, commutes with the r- and c-map. Different members are distinguished by different choices of the paint group, a notion discovered in the context of cosmic billiard dynamics of non-maximally supersymmetric supergravities. We comment on the usefulness of this organization in universality class both in relation with cosmic billiard dynamics and with configurations of branes and orbifolds defining special geometry backgrounds.
Anarjan, Navideh; Jafarizadeh-Malmiri, Hoda; Nehdi, Imededdine Arbi; Sbihi, Hassen Mohamed; Al-Resayes, Saud Ibrahim; Tan, Chin Ping
2015-01-01
Nanodispersion systems allow incorporation of lipophilic bioactives, such as astaxanthin (a fat soluble carotenoid) into aqueous systems, which can improve their solubility, bioavailability, and stability, and widen their uses in water-based pharmaceutical and food products. In this study, response surface methodology was used to investigate the influences of homogenization time (0.5–20 minutes) and speed (1,000–9,000 rpm) in the formation of astaxanthin nanodispersions via the solvent-diffus...
Towards a methanol economy based on homogeneous catalysis: methanol to H_{2} and CO_{2} to methanol
DEFF Research Database (Denmark)
Alberico, E.; Nielsen, Martin
2015-01-01
The possibility to implement both the exhaustive dehydrogenation of aqueous methanol to hydrogen and CO2 and the reverse reaction, the hydrogenation of CO2 to methanol and water, may pave the way to a methanol based economy as part of a promising renewable energy system. Recently, homogeneous...
Antinociceptive activity of Mentha piperita leaf aqueous extract in mice
Taher, Yousef A.
2012-01-01
Background: Mentha piperita L. (Labiatae) is an herbaceous plant, used in folk medicine for the treatment of several medical disorders. Methods and Results: In the present study, the aqueous extract of Mentha piperita leaf, at the i.p doses 200 and 400 mg/kg, showed significant analgesic effects against both acetic acid-induced writhing and hot plateinduced thermal stimulation in mice, with protection values of 51.79% and 20.21% respectively. On the contrary, the Mentha piperita leaf aqueous ...
Synthesis of carboxymethyl chitin in aqueous solution and its thermo- and pH-sensitive behaviors.
Liu, Hui; Yang, Qizhi; Zhang, Lina; Zhuo, Renxi; Jiang, Xulin
2016-02-10
Homogenous modification of natural chitin offers the advantage of fair structure control. In this work, novel carboxymethyl chitins (CMCHs) with broad range of degree of substitution (DS: 0.035 to 0.74), high degree of acetylation (DA) and little de-polymerization were synthesized homogeneously in aqueous NaOH/urea solution. The simultaneous determination of DA, DS and carboxymethylation fraction at C3 and C6 for these CMCHs was achieved by proton NMR in acidic deuterated aqueous solution for the first time. Due to the good homogeneity, the prepared CMCH-4 with lower DS of carboxymethylation exhibited, for the first time to our knowledge, dual thermo- and pH-sensitive properties. The nontoxic thermo-sensitive polymer systems gel at body temperature (37 °C) in physiological condition, which is very useful as injectable hydrogels for drug delivery and tissue engineering. PMID:26686169
Sulfur isotope homogeneity of lunar mare basalts
Wing, Boswell A.; Farquhar, James
2015-12-01
We present a new set of high precision measurements of relative 33S/32S, 34S/32S, and 36S/32S values in lunar mare basalts. The measurements are referenced to the Vienna-Canyon Diablo Troilite (V-CDT) scale, on which the international reference material, IAEA-S-1, is characterized by δ33S = -0.061‰, δ34S ≡ -0.3‰ and δ36S = -1.27‰. The present dataset confirms that lunar mare basalts are characterized by a remarkable degree of sulfur isotopic homogeneity, with most new and published SF6-based sulfur isotope measurements consistent with a single mass-dependent mean isotopic composition of δ34S = 0.58 ± 0.05‰, Δ33S = 0.008 ± 0.006‰, and Δ36S = 0.2 ± 0.2‰, relative to V-CDT, where the uncertainties are quoted as 99% confidence intervals on the mean. This homogeneity allows identification of a single sample (12022, 281) with an apparent 33S enrichment, possibly reflecting cosmic-ray-induced spallation reactions. It also reveals that some mare basalts have slightly lower δ34S values than the population mean, which is consistent with sulfur loss from a reduced basaltic melt prior to eruption at the lunar surface. Both the sulfur isotope homogeneity of the lunar mare basalts and the predicted sensitivity of sulfur isotopes to vaporization-driven fractionation suggest that less than ≈1-10% of lunar sulfur was lost after a potential moon-forming impact event.
Homogeneous almost quaternion-Hermitian manifolds
Moroianu, Andrei; Pilca, Mihaela; Semmelmann, Uwe
2012-01-01
An almost quaternion-Hermitian structure on a Riemannian manifold $(M^{4n},g)$ is a reduction of the structure group of $M$ to $\\mathrm{Sp}(n)\\mathrm{Sp}(1)\\subset \\mathrm{SO}(4n)$. In this paper we show that a compact simply connected homogeneous almost quaternion-Hermitian manifold of non-vanishing Euler characteristic is either a Wolf space, or $\\mathbb{S}^2\\times \\mathbb{S}^2$, or the complex quadric $\\mathrm{SO}(7)/\\mathrm{U}(3)$.
Nonlinear partial differential equations on homogeneous spaces
International Nuclear Information System (INIS)
The work of A.K.N.S. which is based on the s1(2,R) valued soliton connection is extended to obtain new integrable coupled nonlinear partial differential equations. This is achieved by assuming the soliton connection having values in a semisimple Lie, Kac-Moody, Lie super algebras. Extensions of some of the integrable nonlinear p.d.e's are given explicitly. In particular the coupled NLS equations on various homogeneous spaces and the coupled modified KdV equations are obtained on symmetric spaces. (author). 20 refs
Mechanisms in homogeneous and heterogeneous epoxidation catalysis
Oyama, S Ted
2011-01-01
The catalytic epoxidation of olefins plays an important role in the industrial production of several commodity compounds, as well as in the synthesis of many intermediates, fine chemicals, and pharmaceuticals. The scale of production ranges from millions of tons per year to a few grams per year. The diversity of catalysts is large and encompasses all the known categories of catalyst type: homogeneous, heterogeneous, and biological. This book summarizes the current status in these fields concentrating on rates, kinetics, and reaction mechanisms, but also covers broad topics including modeli
REITERATED HOMOGENIZATION OF DEGENERATE NONLINEAR ELLIPTIC EQUATIONS
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The authors study homogenization of some nonlinear partial differential equations of the form -div (a (hx,h2x,Duh)) = f,where a is periodic in the first two arguments and monotone in the third.In particular the case where a satisfies degenerated structure conditions is studied.It is proved that uh converges weakly in Wo1.1 (Ω) to the unique solution of a limit problem as h →∞.Moreover,explicit expressions for the limit problem are obtained.
Spin dynamics through homogeneous magnetic superlattices
International Nuclear Information System (INIS)
We develop a theory to study the spin dynamics of a 2DEG moving across a magnetic superlattice, where the external, tilted and sectionally homogeneous magnetic fields, induce spin transitions between the two spin components, along the superlattice. Using the transfer matrix approach, we provide a joint description of the spatial evolution of the spin-1/2 wave functions: amplitude and phase, in terms of the tilting angle, the Fermi energy and the magnetic field strengths. Clear signatures of coherent spin mixing and coherent spin flipping processes are also obtained. (author)
Homogenizing the dose for adjacent fields
International Nuclear Information System (INIS)
Difficulties are found in radiotherapy in the determination of the gap which should be left among adjacent fields on the skin. In order to homogenize the dose at a given depth, measurements are done with a wood phantom using films, thermoluminescent dosemeters and ionization chambers. Field match is checked according to tables related in the literature and experimental data. Two tables of field separation are built at various depths, one for simultaneous adjacent fields and the other for non-simultaneous adjacent fields. Tables must be checked and the additional distances corrected for each field
'Proserpine'. Homogeneous critical experiment with plutonium
International Nuclear Information System (INIS)
Proserpine is a homogeneous critical experiment in which plutonium is used as a fissile material. This experiment has been designed to investigate static and kinetic parameters of a thermal neutron reactor in which fissile material is highly concentrated. This report proposes a brief description of the installation (core, solution circuits, measurement and level adjustment, reflector, adjustment mechanism and safety, thermostatically-controlled booth and temperature control, installation safety), and presents the experimental program (critical mass, characteristics of the fissile solution, temperature coefficient) and the first results obtained in a zircaloy vessel. This experiment had two main objectives: a minimum critical mass, and an operating safety with respect to contamination risks
Homogeneous viscous universes with magnetic field
International Nuclear Information System (INIS)
In this thesis homogeneous universes are studied containing a large scale magnetic field. In the evolution three different phases are distinguished: the lepton, the plasma and the matter dominated eras. During the lepton and plasma eras, which form the radiation dominated phase, the material contents of the universe are taken to consist of a viscous fluid. The transport properties taking place during this radiation dominated period are described with the help of relativistic kinetic theory, thereby taking into account the effect of the magnetic field on the shear viscosity. In the matter dominated phase the contents of the universe mainly consists of dust and, therefore, viscosity is absent during this period. (Auth.)
Paredes, Alejandro Javier; Llabot, Juan Manuel; Sánchez Bruni, Sergio; Allemandi, Daniel; Palma, Santiago Daniel
2016-10-01
Albendazole (ABZ) is a broad-spectrum antiparasitic drug used in the treatment of human or animal infections. Although ABZ has shown a high efficacy for repeated doses in monogastric mammals, its low aqueous solubility leads to erratic bioavailability. The aim of this work was to optimize a procedure in order to obtain ABZ self-dispersible nanocrystals (SDNC) by combining high pressure homogenization (HPH) and spray-drying (SD). The material thus obtained was characterized and the variables affecting both the HPH and SD processes were studied. As expected, the homogenizing pressure and number of cycles influenced the final particle size, while the stabilizer concentration had a strong impact on SD output and redispersion of powders upon contact with water. ABZ SDNC were successfully obtained with high process yield and redispersibility. The characteristic peaks of ABZ were clearly identified in the X-ray patterns of the processed samples. A noticeable increase in the dissolution rate was observed in the aqueous environment. PMID:26856301
On Shearing Fluids with Homogeneous Densities
Srivastava, D C; Kumar, Rajesh
2016-01-01
In this paper, we study shearing spherically symmetric homogeneous density fluids in comoving coordinates. It is found that the expansion of the four-velocity of a perfect fluid is homogeneous, whereas its shear is generated by an arbitrary function of time M(t), related to the mass function of the distribution. This function is found to bear a functional relationship with density. The field equations are reduced to two coupled first order ordinary differential equations for the metric coefficients, g 11 and g 22. We have explored a class of solutions assuming that M is a linear function of the density. This class embodies, as a subcase, the complete class of shear-free solutions. We have discussed the off quoted work of Kustaanheimo (1947) and have noted that it deals with shear-free fluids having anisotropic pressure. It is shown that the anisotropy of the fluid is characterized by an arbitrary function of time. We have discussed some issues of historical priorities and credentials related to shear-free sol...
Homogeneous cooling of mixtures of particle shapes
Hidalgo, R. C.; Serero, D.; Pöschel, T.
2016-07-01
In this work, we examine theoretically the cooling dynamics of binary mixtures of spheres and rods. To this end, we introduce a generalized mean field analytical theory, which describes the free cooling behavior of the mixture. The relevant characteristic time scale for the cooling process is derived, depending on the mixture composition and the aspect ratio of the rods. We simulate mixtures of spherocylinders and spheres using a molecular dynamics algorithm implemented on graphics processing unit (GPU) architecture. We systematically study mixtures composed of spheres and rods with several aspect ratios and varying the mixture composition. A homogeneous cooling state, where the time dependence of the system's intensive variables occurs only through a global granular temperature, is identified. We find cooling dynamics in excellent agreement with Haff's law, when using an adequate time scale. Using the scaling properties of the homogeneous cooling dynamics, we estimated numerically the efficiency of the energy interchange between rotational and translational degrees of freedom for collisions between spheres and rods.
Photo-electret effects in homogenous semiconductors
International Nuclear Information System (INIS)
In the given work is shown the opportunity and created the theory of photo-electret condition in semiconductors with Dember mechanism of photo-voltage generation. Photo-electret of such type can be created, instead of traditional and without an external field as a result of only one illumination. Polar factor, in this case, is the distinction of electrons and holes mobility. Considered the multilayered structure with homogeneous photoactive micro areas shared by the layers, which are interfering to alignment of carriers concentration. We consider, that the homogeneous photoactive areas contain deep levels of stick. Because of addition of elementary photo voltage in separate micro photo cells it is formed the abnormal-large photo voltage (APV-effect). Let's notice, that Dember photo-voltage in a separate micro photo-cell ≤kT/q. From the received expressions, in practically important, special case, when quasi- balance between valent zone and stick levels established in much more smaller time, than free hole lifetime, and we received, that photo-voltage is relaxing. Comparing of the received expressions with the laws of photo voltage attenuation in p-n- junction structures shows their identity; the difference is only in absolute meanings of photo voltage. During the illumination in the semiconductor are created the superfluous concentration of charge carriers and part from them stays at deep levels. At de-energizing light there is a gradual generation of carriers located at these levels
Irregular Homogeneity Domains in Ternary Intermetallic Systems
Directory of Open Access Journals (Sweden)
Jean-Marc Joubert
2015-12-01
Full Text Available Ternary intermetallic A–B–C systems sometimes have unexpected behaviors. The present paper examines situations in which there is a tendency to simultaneously form the compounds ABx, ACx and BCx with the same crystal structure. This causes irregular shapes of the phase homogeneity domains and, from a structural point of view, a complete reversal of site occupancies for the B atom when crossing the homogeneity domain. This work reviews previous studies done in the systems Fe–Nb–Zr, Hf–Mo–Re, Hf–Re–W, Mo–Re–Zr, Re–W–Zr, Cr–Mn–Si, Cr–Mo–Re, and Mo–Ni–Re, and involving the topologically close-packed Laves, χ and σ phases. These systems have been studied using ternary isothermal section determination, DFT calculations, site occupancy measurement using joint X-ray, and neutron diffraction Rietveld refinement. Conclusions are drawn concerning this phenomenon. The paper also reports new experimental or calculated data on Co–Cr–Re and Fe–Nb–Zr systems.
Homogenization in micro-magneto-mechanics
Sridhar, A.; Keip, M.-A.; Miehe, C.
2016-07-01
Ferromagnetic materials are characterized by a heterogeneous micro-structure that can be altered by external magnetic and mechanical stimuli. The understanding and the description of the micro-structure evolution is of particular importance for the design and the analysis of smart materials with magneto-mechanical coupling. The macroscopic response of the material results from complex magneto-mechanical interactions occurring on smaller length scales, which are driven by magnetization reorientation and associated magnetic domain wall motions. The aim of this work is to directly base the description of the macroscopic magneto-mechanical material behavior on the micro-magnetic domain evolution. This will be realized by the incorporation of a ferromagnetic phase-field formulation into a macroscopic Boltzmann continuum by the use of computational homogenization. The transition conditions between the two scales are obtained via rigorous exploitation of rate-type and incremental variational principles, which incorporate an extended version of the classical Hill-Mandel macro-homogeneity condition covering the phase field on the micro-scale. An efficient two-scale computational scenario is developed based on an operator splitting scheme that includes a predictor for the magnetization on the micro-scale. Two- and three-dimensional numerical simulations demonstrate the performance of the method. They investigate micro-magnetic domain evolution driven by macroscopic fields as well as the associated overall hysteretic response of ferromagnetic solids.
Marmor, J B
1998-01-01
Although many clinical studies suggest the medical utility of marijuana for some conditions, the scientific evidence is weak. Many patients in California are self-medicating with marijuana, and physicians need data to assess the risks and benefits. The only reasonable solution to this problem is to encourage research on the medical effects of marijuana. The current regulatory system should be modified to remove barriers to clinical research with marijuana. The NIH panel has identified several...
Radiolysis of berberine or palmatine in aqueous solution
Marszalek, Milena; Wolszczak, Marian
2011-01-01
The reactions of hydrated electron (eaq-), hydrogen atom (H rad ) (reducing species) and Cl2•-, Br2•-, N,O•H radicals (oxidizing species) with berberine or palmatine in aqueous solution have been studied by steady-state and pulse radiolysis. The spectra of transient intermediates, leading to the final products, are presented. The rate constants of the reaction of eaq- and rad OH radical with both alkaloids in the homogenous solution and in the presence of DNA are reported. It is demonstrated that the primary products of the reaction of berberine and palmatine with eaq- and radicals generated during radiolysis are unstable and undergo further reactions.
Polymerization of beta-amino acids in aqueous solution
Liu, R.; Orgel, L. E.; Bada, J. L. (Principal Investigator)
1998-01-01
We have compared carbonyl diimidazole (CDI) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC) as activating agents for the oligomerization of negatively-charged alpha- and beta-amino acids in homogeneous aqueous solution. alpha-Amino acids can be oligomerized efficiently using CDI, but not by EDAC. beta-Amino acids can be oligomerized efficiently using EDAC, but not by CDI. Aspartic acid, an alpha- and beta-dicarboxylic acid is oligomerized efficiently by both reagents. These results are explained in terms of the mechanisms of the reactions, and their relevance to prebiotic chemistry is discussed.
Li, Feifei
2013-05-21
Lanthanide-doped core-shell upconversion nanocrystals (UCNCs) have tremendous potential for applications in many fields, especially in bio-imaging and medical therapy. As core-shell UCNCs are mostly synthesized in organic solvents, tedious organic-aqueous phase transfer processes are usually needed for their use in bio-applications. Herein, we demonstrate the first example of one-step synthesis of highly luminescent core-shell UCNCs in the "aqueous" phase under mild conditions using innocuous reagents. A microwave-assisted approach allowed for layer-by-layer epitaxial growth of a hydrophilic NaGdF4 shell on NaYF4:Yb, Er cores. During this process, surface defects of the nanocrystals could be gradually passivated by the homogeneous shell deposition, resulting in obvious enhancement in the overall upconversion emission efficiency. In addition, the up-down conversion dual-mode luminescent NaYF4:Yb, Er@NaGdF4:Ce, Ln (Eu, Tb, Sm, Dy) nanocrystals were also synthesized to further validate the successful formation of the core-shell structure. More significantly, based on their superior solubility and stability in water solution, high upconversion efficiency and Gd-doped predominant X-ray absorption, the as-prepared NaYF4:Yb, Er@NaGdF4 core-shell UCNCs exhibited high contrast in in vitro cell imaging and in vivo X-ray computed tomography (CT) imaging, demonstrating great potential as multiplexed luminescent biolabels and CT contrast agents.
Four-dimensional pseudo-Riemannian homogeneous Ricci solitons
Calvaruso, Giovanni; Fino, Anna
2011-01-01
We consider four-dimensional homogeneous pseudo-Riemannian manifolds with non-trivial isotropy and completely classify the cases giving rise to non-trivial homogeneous Ricci solitons. In particular, we show the existence of non-compact homogeneous (and also invariant) pseudo-Riemannian Ricci solitons which are not isometric to solvmanifolds, and of conformally flat homogeneous pseudo-Riemannian Ricci solitons which are not symmetric.
MULTISCALE HOMOGENIZATION OF NONLINEAR HYPERBOLIC EQUATIONS WITH SEVERAL TIME SCALES
Institute of Scientific and Technical Information of China (English)
Jean Louis Woukeng; David Dongo
2011-01-01
We study the multiscale homogenization of a nonlinear hyperbolic equation in a periodic setting. We obtain an accurate homogenization result. We also show that as the nonlinear term depends on the microscopic time variable, the global homogenized problem thus obtained is a system consisting of two hyperbolic equations. It is also shown that in spite of the presence of several time scales, the global homogenized problem is not a reiterated one.
Homogenization of a stationary flow of a generalized Newtonian fluid
Bulíček, Miroslav; Kalousek, Martin; Kaplický, Petr
2016-01-01
We perform the homogenization process avoiding the necessity of testing the weak formulation of the initial and homogenized systems by corresponding weak solutions. We show that the stress tensor for homogenized problem depends on the gradient involving the limit of a sequence selected from a family of solutions of initial problems.
THE ANALYTICAL PROPERTIES FOR HOMOGENEOUS RANDOM TRANSITION FUNCTIONS
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The concepts of Markov process in random environment and homogeneous random transition functions are introduced. The necessary and sufficient conditions for homogeneous random transition function are given. The main results in this article are the analytical properties, such as continuity, differentiability, random Kolmogorov backward equation and random Kolmogorov forward equation of homogeneous random transition functions.
Kumaraswamy, Mohan
2002-01-01
One element of the CIVCAL project Web-based resources containing images, tables, texts and associated data on the construction of the Medical Complex. This project covers the construction of a new Hong Kong University Medical Complex on Sassoon Road, Pokfulam. The complex will comprise two buildings, one will house laboratories and a car park, while the other will contain lecture halls
Magnetism and homogenization of micro-resonators
Kohn, Robert V
2007-01-01
Arrays of cylindrical metal micro-resonators embedded in a dielectric matrix were proposed by Pendry, et. al., in 1999 as a means of creating a microscopic structure that exhibits strong bulk magnetic behavior at frequencies not realized in nature. This behavior arises for H-polarized fields in the quasi-static regime, in which the scale of the micro-structure is much smaller than the free-space wavelength of the fields. We carry out both formal and rigorous two-scale homogenization analyses, paying special attention to the appropriate method of averaging, which does not involve the usual cell averages. We show that the effective magnetic and dielectric coefficients obtained by means of such averaging characterize a bulk medium that, to leading order, produces the same scattering data as the micro-structured composite.
The homogeneous and isotropic Weyssenhoff fluid
Boehmer, C G; Boehmer, Christian G.; Bronowski, Piotr
2006-01-01
We consider a Weyssenhoff fluid assuming that the spacetime is homogeneous and isotropic, therefore being relevant for cosmological considerations of gravity theories with torsion. In this paper, it is explicitely shown that the Weyssenhoff fluids obeying the Frenkel condition or the Papapetrou-Corinaldesi condition are incompatible with the cosmological principle, which restricts the torsion tensor to have only a vector and an axial vector component. Moreover it turns out that the Weyssenhoff fluid obeying the Tulczyjew condition is also incompatible with the cosmological principle. Based on this result we propose to reconsider a number of previous works that analysed cosmological solutions of Einstein-Cartan theory, since their spin fluids usually did not obey the cosmological principle.
The structure and homogeneity of Psalm 32
Directory of Open Access Journals (Sweden)
J. Henk Potgieter
2014-02-01
Full Text Available Psalm 32 is widely regarded as a psalm of thanksgiving with elements of wisdom poetry intermingled into it. The wisdom elements are variously explained as having been present from the beginning, or as having been added to a foundational composition. Such views of the Gattung have had a decisive influence on the interpretation of the psalm. This article argues, on the basis of a structural analysis, that Psalm 32 should be understood as a homogeneous wisdom composition. The parallel and inverse structure of its two stanzas demonstrate that the aim of its author was to encourage the upright to foster an open, intimate relationship with Yahweh in which transgressions are confessed and Yahweh’s benevolent guidance on the way of life is wisely accepted.
Homogeneous spacelike singularities inside spherical black holes
Burko, L M
1997-01-01
Recent numerical simulations have found that the Cauchy horizon inside spherical charged black holes, when perturbed nonlinearly by a self-gravitating, minimally-coupled, massless, spherically-symmetric scalar field, turns into a null weak singularity which focuses monotonically to $r=0$ at late times, where the singularity becomes spacelike. Our main objective is to study this spacelike singularity. We study analytically the spherically-symmetric Einstein-Maxwell-scalar equations asymptotically near the singularity. We obtain a series-expansion solution for the metric functions and for the scalar field near $r=0$ under the simplifying assumption of homogeneity. Namely, we neglect spatial derivatives and keep only temporal derivatives. We find that there indeed exists a generic spacelike singularity solution for these equations (in the sense that the solution depends on enough free parameters), with similar properties to those found in the numerical simulations. This singularity is strong in the Tipler sense,...
Homogeneously dispersed multimetal oxygen-evolving catalysts.
Zhang, Bo; Zheng, Xueli; Voznyy, Oleksandr; Comin, Riccardo; Bajdich, Michal; García-Melchor, Max; Han, Lili; Xu, Jixian; Liu, Min; Zheng, Lirong; García de Arquer, F Pelayo; Dinh, Cao Thang; Fan, Fengjia; Yuan, Mingjian; Yassitepe, Emre; Chen, Ning; Regier, Tom; Liu, Pengfei; Li, Yuhang; De Luna, Phil; Janmohamed, Alyf; Xin, Huolin L; Yang, Huagui; Vojvodic, Aleksandra; Sargent, Edward H
2016-04-15
Earth-abundant first-row (3d) transition metal-based catalysts have been developed for the oxygen-evolution reaction (OER); however, they operate at overpotentials substantially above thermodynamic requirements. Density functional theory suggested that non-3d high-valency metals such as tungsten can modulate 3d metal oxides, providing near-optimal adsorption energies for OER intermediates. We developed a room-temperature synthesis to produce gelled oxyhydroxides materials with an atomically homogeneous metal distribution. These gelled FeCoW oxyhydroxides exhibit the lowest overpotential (191 millivolts) reported at 10 milliamperes per square centimeter in alkaline electrolyte. The catalyst shows no evidence of degradation after more than 500 hours of operation. X-ray absorption and computational studies reveal a synergistic interplay between tungsten, iron, and cobalt in producing a favorable local coordination environment and electronic structure that enhance the energetics for OER. PMID:27013427
Homogeneous cosmology with aggressively expanding civilizations
Olson, S Jay
2014-01-01
In the context of a homogeneous universe, we note that the appearance of aggressively expanding advanced life is geometrically similar to the process of nucleation and bubble growth in a first-order cosmological phase transition. We exploit this similarity to describe the dynamics of life saturating the universe on a cosmic scale, adapting the phase transition model to incorporate probability distributions of expansion and resource consumption strategies. Through a series of numerical solutions covering several orders of magnitude in the input assumption parameters, the resulting cosmological model is used to address basic questions related to the intergalactic spreading of life, dealing with issues such as timescales, observability, competition between strategies, and first-mover advantage. Finally, we examine physical effects on the universe itself, such as reheating and the backreaction on the evolution of the scale factor, if such life is able to control and convert a significant fraction of the available...
Lyapunov Analysis of Homogeneous Isotropic Turbulence
de Divitiis, Nicola
2009-01-01
The present work studies the isotropic and homogeneous turbulence for incompressible fluids, through an opportune Lyapunov analysis, assuming that the turbulence is due to the bifurcations associated to the velocity field. A particular representation of the fluid motion is adopted, where the fluid state variables are expressed in terms of the referential coordinates. The analysis is based on the Taylor and Kolmogorov scales and is developed according to the following four items: 1) Qualitative description of the route toward the turbulence through the bifurcations of the velocity field. 2) Referential description of the motion and calculation of the velocity fluctuation using the Lyapunov analysis of the local deformation. 3) Study of the mechanism of the energy cascade from large to small scales through the Lyapunov analysis of the relative kinematics equations of motion. 4) Determination of the statistics of the velocity difference with the Fourier analysis. %Each item contributes to the formulation of the ...
A Statistical Theory of Homogeneous Isotropic Turbulence
de Divitiis, Nicola
2009-01-01
The present work proposes a theory of isotropic and homogeneous turbulence for incompressible fluids, which assumes that the turbulence is due to the bifurcations associated to the velocity field. The theory is formulated using a representation of the fluid motion which is more general than the classical Navier-Stokes equations, where the fluid state variables are expressed in terms of the referential coordinates. The theory is developed according to the following four items: 1) Study of the route toward the turbulence through the bifurcations analysis of the kinematic equations. 2) Referential description of the motion and calculation of the velocity fluctuation using the Lyapunov analysis of the local deformation. 3) Study of the mechanism of the energy cascade from large to small scales through the Lyapunov analysis of the relative kinematics equations of motion. 4) Determination of the statistics of the velocity difference with the Fourier analysis. Each item contributes to the formulation of the theory. ...
Nanodosimetric track structure in homogeneous extended beams
International Nuclear Information System (INIS)
Physical aspects of particle track structure are important in determining the induction of clustered damage in relevant subcellular structures like the DNA and higher-order genomic structures. The direct measurement of track-structure properties of ionising radiation is feasible today by counting the number of ionizations produced inside a small gas volume. In particular, the so-called track-nano-dosimeter, installed at the TANDEM-ALPI accelerator complex of LNL, measures ionisation cluster-size distributions in a simulated subcellular structure of dimensions 20 nm, corresponding approximately to the diameter of the chromatin fibre. The target volume is irradiated by pencil beams of primary particles passing at specified impact parameter. To directly relate these measured track-structure data to radiobiological measurements performed in broad homogeneous particle beams, these data can be integrated over the impact parameter. This procedure was successfully applied to 240 MeV carbon ions and compared with Monte Carlo simulations for extended fields. (authors)
Conformally compactified homogeneous spaces (Possible Observable Consequences)
International Nuclear Information System (INIS)
Some arguments based on the possible spontaneous violation of the Cosmological Principles (represented by the observed large-scale structures of galaxies), the Cartan-geometry of simple spinors and on the Fock-formulation of hydrogen-atom wave-equation in momentum-space, are presented in favour of the hypothesis that space-time and momentum-space should be both conformally compactified and represented by the two four-dimensional homogeneous spaces of the conformal group, both isomorphic to (S3 X S1)/Z2 and correlated by conformal inversion. Within this framework, the possible common origin for the S0(4) symmetry underlying the geometrical structure of the Universe, of Kepler orbits and of the H-atom is discussed. On of the consequences of the proposed hypothesis could be that any quantum field theory should be naturally free from both infrared and ultraviolet divergences. But then physical spaces defined as those where physical phenomena may be best described, could be different from those homogeneous spaces. A simple, exactly soluble, toy model, valid for a two-dimensional space-time is presented where the conjecture conformally compactified space-time and momentum-space are both isomorphic to (S1 X S1)/Z2, while the physical spaces are two finite lattice which are dual since Fourier transforms, represented by finite, discrete, sums may be well defined on them. Furthermore, a q-deformed SUq(1,1) may be represented on them if q is a root of unity. (author). 22 refs, 3 figs
NMR studies of thermoresponsive polymers in aqueous solutions and hydrogels
Czech Academy of Sciences Publication Activity Database
Spěváček, Jiří
Poznań : Department of Macromolecular Physics, Faculty of Physics and NanoBioMedical Centre, Adam Mickiewicz University in Poznań, The Centre for European Integration, 2014 - (Jurga, S.). s. 27 [Ampere NMR School. 22.06.2014-28.06.2014, Zakopane] R&D Projects: GA ČR(CZ) GA13-23392S Institutional support: RVO:61389013 Keywords : NMR * thermoresponsive polymer * aqueous solution Subject RIV: CD - Macromolecular Chemistry
Dissolution test for homogeneity of mixed oxide fuel pellets
International Nuclear Information System (INIS)
Experiments were performed to determine the relationship between fuel pellet homogeneity and pellet dissolubility. Although, in general, the amount of pellet residue decreased with increased homogeneity, as measured by the pellet figure of merit, the relationship was not absolute. Thus, all pellets with high figure of merit (excellent homogeneity) do not necessarily dissolve completely and all samples that dissolve completely do not necessarily have excellent homogeneity. It was therefore concluded that pellet dissolubility measurements could not be substituted for figure of merit determinations as a measurement of pellet homogeneity. 8 figures, 3 tables
Homogeneity study of candidate reference material in fish matrix
International Nuclear Information System (INIS)
A material is perfectly homogeneous with respect to a given characteristic, or composition, if there is no difference between the values obtained from one part to another. Homogeneity is usually evaluated using analysis of variance (ANOVA). However, the requirement that populations of data to be processed must have a normal distribution and equal variances greatly limits the use of this statistical tool. A more suitable test for assessing the homogeneity of RMs, known as sufficient homogeneity, was proposed by Fearn and Thompson. In this work, we evaluate the performance of the two statistical treatments for assessing homogeneity of methylmercury (MeHg) in candidate reference material of fish tissue
Is it possible to homogenize resonant chiral metamaterials ?
DEFF Research Database (Denmark)
Andryieuski, Andrei; Menzel, Christoph; Rockstuhl, Carsten;
2010-01-01
Homogenization of metamaterials is very important as it makes possible description in terms of effective parameters. In this contribution we consider the homogenization of chiral metamaterials. We show that for some metamaterials there is an optimal meta-atom size which depends on the coupling...... between meta-atoms. We introduce numerical criterion of homogeneity on the basis of the Bloch modes dispersion diagram calculation and a tool to predict the homogeneity limit. We show that some metamaterials with strong coupling between meta-atoms cannot be considered as homogeneous at all...
Mars Aqueous Processing System Project
National Aeronautics and Space Administration — Mars Aqueous Processing System (MAPS) is an innovative method to produce useful building materials from Martian regolith. Acids and bases produced from the regolith...
Mars Aqueous Processing System Project
National Aeronautics and Space Administration — The Mars Aqueous Processing System (MAPS) is a novel technology for recovering oxygen, iron, and other constituents from lunar and Mars soils. The closed-loop...
Antidepressant medications and osteoporosis
DEFF Research Database (Denmark)
Rizzoli, R; Cooper, C; Reginster, J-Y;
2012-01-01
types of bone cell (osteoblasts, osteocytes, and osteoclasts), indicating an important role of the neuroendocrine system in bone. Observational studies indicate a complex relationship between depression, antidepressants, and fracture. First, the presence of depression itself increases fracture risk......, in relation with decreased BMD and an increase in falls. A range of aspects of depression may operate, including behavioral factors (e.g., smoking and nutrition), biological changes, and confounders (e.g., comorbidities and concomitant medications). A substantial proportion of depressed patients receive...... for potential confounders. While there is a dose-response relationship for SSRIs, the effect does not appear to be homogeneous across the whole class of drugs and may be linked to affinity for the serotonin transporter system. The increase in risk is the greatest in the early stages of treatment...
... for Medication For the treatment of heart failure Beta Blockers (Also known as Beta-Adrenergic Blocking Agents) Commonly ... have had a heart attack. Combined alpha and beta-blockers Combined alpha and beta-blockers are used as ...
... behavior, such as to reduce self-injury or aggression. Once a symptom is no longer a problem, ... of repetitive behaviors; decrease anxiety, irritability, tantrums, and aggressive behavior; and improve eye contact. Tricyclics These medications are ...
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International Nuclear Information System (INIS)
This didactical book presents the medical imaging techniques: radiography, scanner, nuclear magnetic resonance (NMR). Examples are given for the most common pathologies in all domains of medicine. (J.S.)
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International Nuclear Information System (INIS)
This leaflet in the At-a-Glance Series describes the medical use of X-rays, how X-rays help in diagnosis, radiation protection of the patient, staff protection, how radioactive materials in nuclear medicine examinations help in diagnosis and the use of radiation in radiotherapy. Magnetic resonance imaging, a diagnostic technique involving no ionizing radiation, is also briefly examined. The role of the NRPB in the medical use of radiation is outlined. (UK)
Abbas Ghanbari; Khadijeh Zirak Moradlu; Morteza Ramazani
2014-01-01
Medical tourism is considered as one of the tourism dimensions and it can contribute to the stabilized and dynamic development of a country's economy. Since it is cost-effective industry, most developing countries have focused on this industry and they are planning to develop this industry. Not only does Zanjan province, as the central region in medicine services, enjoy different kinds of variety and acceptable medical specialties but also it has historical, natural, and religious tourism pot...
Compositional Homogeneity of CM Parent Bodies
Vernazza, P.; Marsset, M.; Beck, P.; Binzel, R. P.; Birlan, M.; Cloutis, E. A.; DeMeo, F. E.; Dumas, C.; Hiroi, T.
2016-09-01
CM chondrites are the most common type of hydrated meteorites, making up ˜1.5% of all falls. Whereas most CM chondrites experienced only low-temperature (˜0°C–120°C) aqueous alteration, the existence of a small fraction of CM chondrites that suffered both hydration and heating complicates our understanding of the early thermal evolution of the CM parent body(ies). Here, we provide new constraints on the collisional and thermal history of CM-like bodies from a comparison between newly acquired spectral measurements of main-belt Ch/Cgh-type asteroids (70 objects) and existing laboratory spectral measurements of CM chondrites. It first appears that the spectral variation observed among CM-like bodies is essentially due to variations in the average regolith grain size. Second, the spectral properties of the vast majority (unheated) of CM chondrites resemble both the surfaces and the interiors of CM-like bodies, implying a “low” temperature (origin is the likely explanation for the existence of heated CM chondrites. Finally, similarly to S-type asteroids and (2) Pallas, the surfaces of large (D > 100 km)—supposedly primordial—Ch/Cgh-type main-belt asteroids likely expose the interiors of the primordial CM parent bodies, a possible consequence of impacts by small asteroids (D solar system.
Compositional Homogeneity of CM Parent Bodies
Vernazza, P.; Marsset, M.; Beck, P.; Binzel, R. P.; Birlan, M.; Cloutis, E. A.; DeMeo, F. E.; Dumas, C.; Hiroi, T.
2016-09-01
CM chondrites are the most common type of hydrated meteorites, making up ˜1.5% of all falls. Whereas most CM chondrites experienced only low-temperature (˜0°C–120°C) aqueous alteration, the existence of a small fraction of CM chondrites that suffered both hydration and heating complicates our understanding of the early thermal evolution of the CM parent body(ies). Here, we provide new constraints on the collisional and thermal history of CM-like bodies from a comparison between newly acquired spectral measurements of main-belt Ch/Cgh-type asteroids (70 objects) and existing laboratory spectral measurements of CM chondrites. It first appears that the spectral variation observed among CM-like bodies is essentially due to variations in the average regolith grain size. Second, the spectral properties of the vast majority (unheated) of CM chondrites resemble both the surfaces and the interiors of CM-like bodies, implying a “low” temperature (body(ies). It follows that an impact origin is the likely explanation for the existence of heated CM chondrites. Finally, similarly to S-type asteroids and (2) Pallas, the surfaces of large (D > 100 km)—supposedly primordial—Ch/Cgh-type main-belt asteroids likely expose the interiors of the primordial CM parent bodies, a possible consequence of impacts by small asteroids (D < 10 km) in the early solar system.
Persymmetric Adaptive Detectors of Subspace Signals in Homogeneous and Partially Homogeneous Clutter
Directory of Open Access Journals (Sweden)
Ding Hao
2015-08-01
Full Text Available In the field of adaptive radar detection, an effective strategy to improve the detection performance is to exploit the structural information of the covariance matrix, especially in the case of insufficient reference cells. Thus, in this study, the problem of detecting multidimensional subspace signals is discussed by considering the persymmetric structure of the clutter covariance matrix, which implies that the covariance matrix is persymmetric about its cross diagonal. Persymmetric adaptive detectors are derived on the basis of the one-step principle as well as the two-step Generalized Likelihood Ratio Test (GLRT in homogeneous and partially homogeneous clutter. The proposed detectors consider the structural information of the covariance matrix at the design stage. Simulation results suggest performance improvement compared with existing detectors when reference cells are insufficient. Moreover, the detection performance is assessed with respect to the effects of the covariance matrix, signal subspace dimension, and mismatched performance of signal subspace as well as signal fluctuations.
Energy Technology Data Exchange (ETDEWEB)
Escher, A; Boulouchos, K.
2006-12-15
This annual report for the Swiss Federal Office of Energy (SFOE) reports on work done in 2006 at the Laboratory for Aero-thermochemistry and Combustion Systems at the Swiss Federal Institute of Technology ETH in Zurich, Switzerland, on the simulation of homogeneous self-igniting combustion. It also presents the results of experimental work on the ignition of n-butane and n-heptane in the institute's one-stroke test engine. Two simulation methods are discussed, both of which corresponded well with the results of experiments carried out. The authors note that the results provide a deeper insight into the mechanisms of self-ignition in homogeneous mixtures.
Nearsightedness of Finite Homogeneous Model Systems
Mitsuta, Yuki; Yamanaka, Shusuke; Kawakami, Takashi; Okumura, Mitsutaka; Yamaguchi, Kizashi; Nakamura, Haruki
On the basis of linear response function (LRF) analysis, nearsightedness of finite systems is examined for nearly homogeneous molecular systems. We first treated with Hn (n = 2-100) to inspect the local or nonlocal responses of these systems, which are, in other words, the magnitudes of nearsightedness of the finite systems. Further, the LRFs of H100n+ (n = 0-98) have been examined in order to clarify whether the magnitude of nearsightedness depends either the size of systems or the number of electrons in systems. From our calculations, we conjectured that the number of electrons are essential for nearsightedness of electronic matter (NEM) of this type of systems. This conjecture has been confirmed from the fact that the LRFs of H100n+ (n = 0-98) are similar to those of N electrons (N = 2-100) in a square well potential, showing that attractive potentials of H100n+ (n = 0-98) do not change significantly the dependence of the magnitudes of NEM on the number of electrons.
Numerical Computation of Homogeneous Slope Stability
Directory of Open Access Journals (Sweden)
Shuangshuang Xiao
2015-01-01
Full Text Available To simplify the computational process of homogeneous slope stability, improve computational accuracy, and find multiple potential slip surfaces of a complex geometric slope, this study utilized the limit equilibrium method to derive expression equations of overall and partial factors of safety. This study transformed the solution of the minimum factor of safety (FOS to solving of a constrained nonlinear programming problem and applied an exhaustive method (EM and particle swarm optimization algorithm (PSO to this problem. In simple slope examples, the computational results using an EM and PSO were close to those obtained using other methods. Compared to the EM, the PSO had a small computation error and a significantly shorter computation time. As a result, the PSO could precisely calculate the slope FOS with high efficiency. The example of the multistage slope analysis indicated that this slope had two potential slip surfaces. The factors of safety were 1.1182 and 1.1560, respectively. The differences between these and the minimum FOS (1.0759 were small, but the positions of the slip surfaces were completely different than the critical slip surface (CSS.
Redatuming Operators Analysis in Homogeneous Media
Oliveira, Fransisco de Souza; Figueiredo, Jose J. S. de; Freitas, Lucas
2015-04-01
A redatuming operation is used to simulate the acquisition of data in new levels, avoiding distortions produced by near-surface irregularities related to either geometric or material property heterogeneities. In this work, the application of the true-amplitude Kirchhoff redatuming (TAKR) operator on homogeneous media is compared with conventional Kirchhoff redatuming (KR) operator restricted to the zero-offset case. The TAKR and the KR operators are analytically and numerically compared in order to verify their impacts on the data at a new level. Analyses of amplitude and velocity sensitivity of the TAKR and KR were performed: one concerning the difference between the weight functions and the other related to the velocity variation. The comparisons between operators were performed using numerical examples. The feasibility of the KR and TAKR operators was demonstrated not only kinematically but also dynamically for their purposes. In other words, one preserves amplitude (KR), and the other corrects the amplitude (TAKR). In the end, we applied the operators to a GPR data set.
Pair reversal in homogeneous isotropic turbulence
International Nuclear Information System (INIS)
We show that the separation of particle pairs in the inertial subrange of homogeneous isotropic turbulence is strongly influenced by the pairs that separate quasi-diffusively. We quantify the influence of the diffusive separators by considering the probability that a pair will 'reverse' direction across a given separation i.e. its separation will decrease (before eventually increasing) and derive an analytical expression for the expected number of reversals across this separation for a quasi-one-dimensional model of relative dispersion in the inertial subrange with Gaussian turbulence. We compare this theoretical result with three different Lagrangian stochastic models in which the influence of the diffusive and ballistic separators (the latter dominated by velocity memory) can be varied by means of the value of C0, the constant of proportionality in the Lagrangian velocity structure function, which appears explicitly in Lagrangian stochastic models. We also compare these results with data from a direct numerical simulation of turbulence. The results indicate the importance of the transverse relative velocity component (i.e. the ability of pairs to rotate), which is absent in Q1D models, in determining the correct quantitative relative dispersion statistics.
Forming homogeneous clusters for differential risk information
International Nuclear Information System (INIS)
Latent risk situations are always present in society. General information on these risk situations is supposed to be received differently by different groups of people in the population. In the aftermath of specific accidents different groups presumably have need of specific information about how to act to survive, to avoid injuries, to find more information, to obtain facts about the accidents etc. As targets for information these different groups could be defined in different ways. The conventional way is to divide the population according to demographic variables, such as age, sex, occupation etc. Another way would be to structure the population according to dependent variables measured in different studies. They may concern risk perception, emotional reactions, specific technical knowledge of the accidents, and belief in the information sources. One procedure for forming such groupings of people into homogeneous clusters would be by statistical clustering methods on dependent variables. Examples of such clustering procedures are presented and discussed. Data are from a Norwegian study on the perception of radiation from nuclear accidents and other radiation sources. Speculations are made on different risk information strategies. Elements of a research programme are proposed. (author)
Homogeneous screening assay for human tankyrase.
Narwal, Mohit; Fallarero, Adyary; Vuorela, Pia; Lehtiö, Lari
2012-06-01
Tankyrase, a member of human PARP protein superfamily, catalyzes a covalent post-translational modification of substrate proteins. This modification, poly(ADP-ribos)ylation, leads to changes in protein interactions and modifies downstream signaling events. Tankyrase 1 is a potential drug target due to its functions in telomere homeostasis and in Wnt signaling. We describe here optimization and application of an activity-based homogenous assay for tankyrase inhibitors in a high-throughput screening format. The method measures the consumption of substrate by the chemical conversion of the remaining NAD(+) into a stable fluorescent condensation product. Conditions were optimized to measure the enzymatic auto-modification of a recombinant catalytic fragment of tankyrase 1. The fluorescence assay is inexpensive, operationally easy and performs well according to the statistical analysis (Z'= 0.7). A validatory screen with a natural product library confirmed suitability of the assay for finding new tankyrase inhibitors. Flavone was the most potent (IC(50)=325 nM) hit from the natural compounds. A flavone derivative, apigenin, and isopropyl gallate showed potency on the micromolar range, but displayed over 30-fold selectivity for tankyrase over the studied isoenzymes PARP1 and PARP2. The assay is robust and will be useful for screening new tankyrase inhibitors. PMID:22357873
Development of a mechanical homogenizer coffee
Directory of Open Access Journals (Sweden)
Raphael Magalhães Gomes Moreira
2013-12-01
Full Text Available The crop Coffee demands investments to the machines development, which it enables the processes ofpost-harvesting, becoming them faster, meanwhile improving the working. The use of stationary layer dryers are responsible for good results at drying and product quality, but it requires a constant revolving, in order to homogenize the grain mass and improve the air distribution inside the drying chamber. The shortage of workmanship, associated to the need of constant revolving and the heavy working conditions, it becomes it indispensable to mechanize, in some way, this step. The agricultural machine design is considered of great complexity, regarding it must be concerned with the interactions among the operator, machine and environment. When designing a machine, the experience and the dominion of several standpoints have to be interpreted clearly. With the increasing competitiveness on the consumer market and agricultural machines, several companies have joined the research centers, because in general, do not make use of systematic procedures during the project, which can result in failures during operation. This article aimed to design and build a semi-mechanized revolving prototype used to mix the coffee beans. The revolving prototype with the helical screw principles proved to be able to performing the grains transport efficiently.
Theoretical studies of homogeneous catalysts mimicking nitrogenase.
Sgrignani, Jacopo; Franco, Duvan; Magistrato, Alessandra
2011-01-01
The conversion of molecular nitrogen to ammonia is a key biological and chemical process and represents one of the most challenging topics in chemistry and biology. In Nature the Mo-containing nitrogenase enzymes perform nitrogen 'fixation' via an iron molybdenum cofactor (FeMo-co) under ambient conditions. In contrast, industrially, the Haber-Bosch process reduces molecular nitrogen and hydrogen to ammonia with a heterogeneous iron catalyst under drastic conditions of temperature and pressure. This process accounts for the production of millions of tons of nitrogen compounds used for agricultural and industrial purposes, but the high temperature and pressure required result in a large energy loss, leading to several economic and environmental issues. During the last 40 years many attempts have been made to synthesize simple homogeneous catalysts that can activate dinitrogen under the same mild conditions of the nitrogenase enzymes. Several compounds, almost all containing transition metals, have been shown to bind and activate N₂ to various degrees. However, to date Mo(N₂)(HIPTN)₃N with (HIPTN)₃N= hexaisopropyl-terphenyl-triamidoamine is the only compound performing this process catalytically. In this review we describe how Density Functional Theory calculations have been of help in elucidating the reaction mechanisms of the inorganic compounds that activate or fix N₂. These studies provided important insights that rationalize and complement the experimental findings about the reaction mechanisms of known catalysts, predicting the reactivity of new potential catalysts and helping in tailoring new efficient catalytic compounds. PMID:21221062
Theoretical Studies of Homogeneous Catalysts Mimicking Nitrogenase
Directory of Open Access Journals (Sweden)
Alessandra Magistrato
2011-01-01
Full Text Available The conversion of molecular nitrogen to ammonia is a key biological and chemical process and represents one of the most challenging topics in chemistry and biology. In Nature the Mo-containing nitrogenase enzymes perform nitrogen ‘fixation’ via an iron molybdenum cofactor (FeMo-co under ambient conditions. In contrast, industrially, the Haber-Bosch process reduces molecular nitrogen and hydrogen to ammonia with a heterogeneous iron catalyst under drastic conditions of temperature and pressure. This process accounts for the production of millions of tons of nitrogen compounds used for agricultural and industrial purposes, but the high temperature and pressure required result in a large energy loss, leading to several economic and environmental issues. During the last 40 years many attempts have been made to synthesize simple homogeneous catalysts that can activate dinitrogen under the same mild conditions of the nitrogenase enzymes. Several compounds, almost all containing transition metals, have been shown to bind and activate N2 to various degrees. However, to date Mo(N2(HIPTN3N with (HIPTN3N= hexaisopropyl-terphenyl-triamidoamine is the only compound performing this process catalytically. In this review we describe how Density Functional Theory calculations have been of help in elucidating the reaction mechanisms of the inorganic compounds that activate or fix N2. These studies provided important insights that rationalize and complement the experimental findings about the reaction mechanisms of known catalysts, predicting the reactivity of new potential catalysts and helping in tailoring new efficient catalytic compounds.
Inhomogeneous radiative forcing of homogeneous greenhouse gases
Huang, Yi; Tan, Xiaoxiao; Xia, Yan
2016-03-01
Radiative forcing of a homogeneous greenhouse gas (HGG) can be very inhomogeneous because the forcing is dependent on other atmospheric and surface variables. In the case of doubling CO2, the monthly mean instantaneous forcing at the top of the atmosphere is found to vary geographically and temporally from positive to negative values, with the range (-2.5-5.1 W m-2) being more than 3 times the magnitude of the global mean value (2.3 W m-2). The vertical temperature change across the atmospheric column (temperature lapse rate) is found to be the best single predictor for explaining forcing variation. In addition, the masking effects of clouds and water vapor also contribute to forcing inhomogeneity. A regression model that predicts forcing from geophysical variables is constructed. This model can explain more than 90% of the variance of the forcing. Applying this model to analyzing the forcing variation in the Climate Model Intercomparison Project Phase 5 models, we find that intermodel discrepancy in CO2 forcing caused by model climatology leads to considerable discrepancy in their projected change in poleward energy transport.
Homogeneous cosmology with aggressively expanding civilizations
Olson, S. Jay
2015-11-01
In the context of a homogeneous Universe, we note that the appearance of aggressively expanding advanced life is geometrically similar to the process of nucleation and bubble growth in a first-order cosmological phase transition. We exploit this similarity to describe the dynamics of life saturating the Universe on a cosmic scale, adapting the phase transition model to incorporate probability distributions of expansion and resource consumption strategies. Through a series of numerical solutions spanning several orders of magnitude in the input assumption parameters, the resulting cosmological model is used to address basic questions related to the intergalactic spreading of life, dealing with issues such as timescales, observability, competition between strategies, and first-mover advantage. Finally, we examine physical effects on the Universe itself, such as reheating and the backreaction on the evolution of the scale factor, if such life is able to control and convert a significant fraction of the available pressureless matter into radiation. We conclude that the existence of life, if certain advanced technologies are practical, could have a significant influence on the future large-scale evolution of the Universe.
Variation principle of piezothermoelastic bodies, canonical equation and homogeneous equation
Institute of Scientific and Technical Information of China (English)
LIU Yan-hong; ZHANG Hui-ming
2007-01-01
Combining the symplectic variations theory, the homogeneous control equation and isoparametric element homogeneous formulations for piezothermoelastic hybrid laminates problems were deduced. Firstly, based on the generalized Hamilton variation principle, the non-homogeneous Hamilton canonical equation for piezothermoelastic bodies was derived. Then the symplectic relationship of variations in the thermal equilibrium formulations and gradient equations was considered, and the non-homogeneous canonical equation was transformed to homogeneous control equation for solving independently the coupling problem of piezothermoelastic bodies by the incensement of dimensions of the canonical equation. For the convenience of deriving Hamilton isoparametric element formulations with four nodes, one can consider the temperature gradient equation as constitutive relation and reconstruct new variation principle. The homogeneous equation simplifies greatly the solution programs which are often performed to solve nonhomogeneous equation and second order differential equation on the thermal equilibrium and gradient relationship.
Loefler, I J
2001-10-01
The issue of professional migration, however emotional it may have become, ought not to be regarded in moralizing terms. The history of western medicine is the history of migrating physicians. A doctor who moves from a locality to another to take up a new assignment there cannot be said to have "abandoned his patients". This emotional bond has become the victim of specialization and of depersonalization of medical services and not of medical migration, brain drain or otherwise. The primary reason for medical migration is not financial; the desire to migrate usually begins with the desire to learn. Professionals crave in the first line for professional satisfaction. The migration of medical manpower cannot be stopped with administrative measures and will not be stopped by exhortations and appeals, moralization and condemnations. Brain drain is a global phenomenon and has always been so. A country which loses its professionals, its doctors, should examine the social relationships within the profession and should investigate whether the opportunities for deriving professional satisfaction from everyday work exist or whether these have been thwarted by the hierarchy, conservatism, cronyism and the general lack of comprehension of what good medical care is about. PMID:11593497
Line segments in homogeneous scalar turbulence
Gauding, Michael; Goebbert, Jens Henrik; Hasse, Christian; Peters, Norbert
2015-09-01
The local structure of a turbulent scalar field in homogeneous isotropic turbulence is analyzed by direct numerical simulations (DNS) with different Taylor micro-scale based Reynolds numbers between 119 and 529. A novel signal decomposition approach is introduced where the signal of the scalar along a straight line is partitioned into segments based on the local extremal points of the scalar field. These segments are then parameterized by the distance ℓ between adjacent extremal points and the scalar difference Δϕ at the extrema. Both variables are statistical quantities and a joint distribution function of these quantities contains most information to statistically describe the scalar field. It is highlighted that the marginal distribution function of the length becomes independent of Reynolds number when normalized by the mean length ℓm. From a statistical approach, it is further shown that the mean length scales with the Kolmogorov length, which is also confirmed by DNS. For turbulent mixing, the scalar gradient plays a paramount role. Turbulent scalar fields are characterized by cliff-ramp-like structures manifesting the occurrence of localized large scalar gradients. To study turbulent mixing, a segment-based gradient is defined as Δϕ/ℓ. Joint statistics of the length and the segment-based gradient provide novel understanding of cliff-ramp-like structures. Ramp-like structures are unveiled by the asymmetry of the joint distribution function of the segment-based gradient and the length. Cliff-like structures are further analyzed by conditional statistics and it is shown from DNS that the width of cliffs scales with the Kolmogorov length scale.
Structure of homogeneous nonhelical magnetohydrodynamic turbulence
Energy Technology Data Exchange (ETDEWEB)
Miller, R.S.; Mashayek, F.; Adumitroaie, V.; Givi, P. [Department of Mechanical and Aerospace Engineering, State University of New York at Buffalo, Buffalo, New York 14260-4400 (United States)
1996-09-01
Results are presented for three-dimensional direct numerical simulations of nonhelical magnetohydrodynamic (MHD) turbulence for both stationary isotropic and homogeneous shear flow configurations with zero mean induction and unity magnetic Prandtl number. Small scale dynamo action is observed in both flows, and stationary values for the ratio of magnetic to kinetic energy are shown to scale nearly linearly with the Taylor microscale Reynolds numbers above a critical value of Re{sub {lambda}}{approx_equal}30. The presence of the magnetic field has the effect of decreasing the kinetic energy of the flow, while simultaneously increasing the Taylor microscale Reynolds number due to enlargement of the hydrodynamic length scales. For shear flows, both the velocity and the magnetic fields become increasingly anisotropic with increasing initial magnetic field strength. The kinetic energy spectra show a relative increase in high wave-number energy in the presence of a magnetic field. The magnetic field is found to portray an intermittent behavior, with peak values of the flatness near the critical Reynolds number. The magnetic field of both flows is organized in the form of {open_quote}{open_quote}flux tubes{close_quote}{close_quote} and magnetic {open_quote}{open_quote}sheets.{close_quote}{close_quote} These regions of large magnetic field strength show a small correlation with moderate vorticity regions, while the electric current structures are correlated with large amplitude strain regions of the turbulence. Some of the characteristics of small scale MHD turbulence are explained via the {open_quote}{open_quote}structural{close_quote}{close_quote} description of turbulence. {copyright} {ital 1996 American Institute of Physics.}
Structure of homogeneous nonhelical magnetohydrodynamic turbulence
International Nuclear Information System (INIS)
Results are presented for three-dimensional direct numerical simulations of nonhelical magnetohydrodynamic (MHD) turbulence for both stationary isotropic and homogeneous shear flow configurations with zero mean induction and unity magnetic Prandtl number. Small scale dynamo action is observed in both flows, and stationary values for the ratio of magnetic to kinetic energy are shown to scale nearly linearly with the Taylor microscale Reynolds numbers above a critical value of Reλ≅30. The presence of the magnetic field has the effect of decreasing the kinetic energy of the flow, while simultaneously increasing the Taylor microscale Reynolds number due to enlargement of the hydrodynamic length scales. For shear flows, both the velocity and the magnetic fields become increasingly anisotropic with increasing initial magnetic field strength. The kinetic energy spectra show a relative increase in high wave-number energy in the presence of a magnetic field. The magnetic field is found to portray an intermittent behavior, with peak values of the flatness near the critical Reynolds number. The magnetic field of both flows is organized in the form of open-quote open-quote flux tubes close-quote close-quote and magnetic open-quote open-quote sheets.close-quote close-quote These regions of large magnetic field strength show a small correlation with moderate vorticity regions, while the electric current structures are correlated with large amplitude strain regions of the turbulence. Some of the characteristics of small scale MHD turbulence are explained via the open-quote open-quote structural close-quote close-quote description of turbulence. copyright 1996 American Institute of Physics
On a certain approach to quantum homogeneous spaces
Kasprzak, Pawel
2010-01-01
We propose a definition of a quantum homogeneous space of a locally compact quantum group. We show that classically it reduces to the notion of a homogeneous spaces. On the quantum level our definition goes beyond the quotient case. It provides a framework which, besides the Vaes' quotient of a locally compact quantum group by its closed quantum subgroup (our main motivation) is also compatible with, generically non-quotient, quantum homogeneous spaces of a compact quantum group studied by P....
A Modified Homogeneous Balance Method and Its Applications
Institute of Scientific and Technical Information of China (English)
刘春平
2011-01-01
A modified homogeneous balance method is proposed by improving some key steps in the homogeneous balance method. Bilinear equations of some nonlinear evolution equations are derived by using the modified homogeneous balance method. Generalized Boussinesq equation, KP equation, and mKdV equation are chosen as examples to illustrate our method. This approach is also applicable to a large variety of nonlinear evolution equations.
Defining Least Community as a Homogeneous Group in Complex Networks
Jiang, Bin; Ma, Ding
2015-01-01
This paper introduces a new concept of least community that is as homogeneous as a random graph, and develops a new community detection algorithm from the perspective of homogeneity or heterogeneity. Based on this concept, we adopt head/tail breaks - a newly developed classification scheme for data with a heavy-tailed distribution - and rely on edge betweenness given its heavy-tailed distribution to iteratively partition a network into many heterogeneous and homogeneous communities. Surprisin...
Some Characteristic Quantities Associated with Homogeneous -Type and -Type Functions
Directory of Open Access Journals (Sweden)
Cho Yeol Je
2007-01-01
Full Text Available Several characteristic quantities associated with homogeneous -type and -type functions are introduced and studied in this paper. Further, the concepts of -property and -property for a couple of functions are introduced and some quantities for a pair of homogeneous functions having -property and -property are obtained, respectively. As an application, a bound for the solution of the homogeneous complementarity problem with a -type function is derived.
Invariant holomorphic foliations on Kobayashi hyperbolic homogeneous manifolds
Bracci, Filippo; McKay, Benjamin
2011-01-01
Let $M=G/H$ be a Kobayashi hyperbolic, homogeneous complex manifold endowed with a non-singular, $G$-invariant, holomorphic foliation $\\mathcal F$. We show that $\\mathcal F$ is given by a $G$-equivariant, holomorphic fibration over a hyperbolic, $G$-homogeneous complex manifold. If the codimension of $\\mathcal F$ is $1,2$ or 3, this fibration is trivial and $M$ is biholomorphic to the product of hyperbolic, homogeneous complex manifolds.
Operator Algebra Quantum Homogeneous Spaces of Universal Gauge Groups
Mahanta, Snigdhayan; Mathai, Varghese
2011-09-01
In this paper, we quantize universal gauge groups such as SU(∞), as well as their homogeneous spaces, in the σ- C*-algebra setting. More precisely, we propose concise definitions of σ- C*-quantum groups and σ- C*-quantum homogeneous spaces and explain these concepts here. At the same time, we put these definitions in the mathematical context of countably compactly generated spaces as well as C*-compact quantum groups and homogeneous spaces. We also study the representable K-theory of these spaces and compute these groups for the quantum homogeneous spaces associated to the quantum version of the universal gauge group SU(∞).
Holden, Elizabeth A
2012-01-01
Leases for medical space can have far-reaching (and sometimes unintentional) consequences for the future of the practice and the costs of the business. In order to prevent hardship and expense down the line, it is especially important to review the lease to make sure that it reflects the practice's goals, needs, and structure. This article provides a number of provisions that are especially crucial to review and negotiate when leasing medical space, including use restrictions, assignment and subleasing clauses, build-out terms, and legal compliance requirements. PMID:22594070
Biscari, C
2014-01-01
The use of accelerators for medical applications has evolved from initial experimentation to turn-key devices commonly operating in hospitals. New applications are continuously being developed around the world, and the hadrontherapy facilities of the newest generation are placed at the frontier between industrial production and advanced R&D. An introduction to the different medical application accelerators is followed by a description of the hadrontherapy facilities, with special emphasis on CNAO, and the report closes with a brief outlook on the future of this field.
Non-Aqueous Capillary Electrophoresis
Szumski, Michał; Buszewski, Bogusław
Non-aqueous capillary electrophoresis and capillary electrochromatography are special variants of these techniques. Here, organic solvents or their mixtures with or without dissolved electrolytes are used as separation buffer or mobile phase, respectively. The most important features of non-aqueous systems are: better solubility of more hydrophobic ionic substances (many natural products) than in water, much less current and Joule heating allows for using highly concentrated buffers and/or larger capillary internal diameters, polar interactions are enhanced in organic solvents which is often highly advantageous in chiral separation systems. This chapter presents most frequently used solvents, their properties, as well as shows pH* scale which is often used in non-aqueous systems.
Amphoteric Aqueous Hafnium Cluster Chemistry.
Goberna-Ferrón, Sara; Park, Deok-Hie; Amador, Jenn M; Keszler, Douglas A; Nyman, May
2016-05-17
Selective dissolution of hafnium-peroxo-sulfate films in aqueous tetramethylammonium hydroxide enables extreme UV lithographic patterning of sub-10 nm HfO2 structures. Hafnium speciation under these basic conditions (pH>10), however, is unknown, as studies of hafnium aqueous chemistry have been limited to acid. Here, we report synthesis, crystal growth, and structural characterization of the first polynuclear hydroxo hafnium cluster isolated from base, [TMA]6 [Hf6 (μ-O2 )6 (μ-OH)6 (OH)12 ]⋅38 H2 O. The solution behavior of the cluster, including supramolecular assembly via hydrogen bonding is detailed via small-angle X-ray scattering (SAXS) and electrospray ionization mass spectrometry (ESI-MS). The study opens a new chapter in the aqueous chemistry of hafnium, exemplifying the concept of amphoteric clusters and informing a critical process in single-digit-nm lithography. PMID:27094575
Energy Technology Data Exchange (ETDEWEB)
Schneider, B.; Boulouchos, K.
2008-07-01
This annual report for the year 2008 for the Swiss Federal Office of Energy (SFOE) reviews work done at the Swiss Federal Institute of Technology in Zurich, Switzerland, concerning the theoretical and experimental study of self-igniting fuel-air combustion processes that occur in HCCI (Homogeneous Charge Compression Ignition) engines. The work done in 2008 is reviewed, including the systematic search for better injection strategies and cylinder head design. Over 100 intricate calculation runs were made, each needing more than a day of computation and evaluation time. Experimental work in the institute's engine laboratory is also reviewed.
Markov Chain Computation for Homogeneous and Non-homogeneous Data: MARCH 1.1 Users Guide
Directory of Open Access Journals (Sweden)
Andre Berchtold
2001-03-01
Full Text Available MARCH is a free software for the computation of different types of Markovian models including homogeneous Markov Chains, Hidden Markov Models (HMMs and Double Chain Markov Models (DCMMs. The main characteristic of this software is the implementation of a powerful optimization method for HMMs and DCMMs combining a genetic algorithm with the standard Baum-Welch procedure. MARCH is distributed as a set of Matlab functions running under Matlab 5 or higher on any computing platform. A PC Windows version running independently from Matlab is also available.
Simulation of homogeneous diesel combustion processes; Simulation homogener Diesel-Brennverfahren
Energy Technology Data Exchange (ETDEWEB)
Bauer, Clemens
2008-07-01
For the modeling of ignition and combustion of homogeneous Diesel combustion processes two modeling approaches were developed. In both approaches the heat release during the cool flame phase as the first phase of the homogeneous combustion process is considered. The first approach is called Multi-SR approach within this work and is based on the coupling of a system of stochastic reactors with a 3d-CFD-code. The stochastic reactors are modeled in a langrangian way by particles which are moved convectively with the flow field. Depending on the local position they represent their surrounding area in the combustion chamber. Information concerning convection, evaporation, wall heat transfer as well as the turbulent timescale needed for the turbulent mixing process are transferred from the 3d-CFC-Code to the stochastic reactors. With this modeling approach ignition and combustion are implicitly considered. The second approach is a progress variable one with the reaction time as progress variable used for the turbulent description of the ignition phase of homogeneous Diesel combustion processes. The model is based on an online-generated library. Within this library the laminar heat release rates are calculated depending on the reaction time. Based on the library the turbulent released energy during the ignition phase is calculated. In the end the turbulent released energy is coupled to the 3d-CFC-Code based on a simple chemical reaction. After reaching a predefined criterion the ignition model is switched to a conventional Diesel combustion model. With this model the main combustion part is simulated then. The Multi-SR-approach as well as the progress variable approach were implemented in the three-dimensional CFD-Code KIVA [87] and validated with single cylinder data. In most cases the Multi-SR-approach showed a good agreement respect to start of the cool flame and main combustion, maximum pressure and post flame behaviour. The heat release rate during the cool flame
Energy Technology Data Exchange (ETDEWEB)
Bazzaoui, M. [Faculdade de Engenharia, Departamento de Engenharia Quimica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal)]. E-mail: bazzaoui@fe.up.pt; Martins, J.I. [Faculdade de Engenharia, Departamento de Engenharia Quimica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal); Reis, T.C. [Faculdade de Engenharia, Departamento de Engenharia Quimica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal); Bazzaoui, E.A. [Faculte des Sciences, Departement de Chimie, Universite Mohammed I er, 60 000 Oujda (Morocco); Nunes, M.C. [Faculdade de Engenharia, Departamento de Electrotecnica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal); Martins, L. [Centre de Recherche Public de la Sante, 18 rue Dicks (Luxembourg)
2005-08-01
The electrodeposition of polypyrrole (PPy) on oxidizable metals such as aluminum and iron has been achieved in aqueous medium of saccharin and pyrrole. Scanning electron microscopy and X-ray photoelectron spectroscopy analysis reveal a good homogeneity of the obtained PPy film. The electrochemical synthesis of PPy coating has been achieved successfully under potentiodynamic, galvanostatic and potentiostatic techniques. The corrosion experiments performed in HCl show that the PPy coating increases the corrosion potential and decreases the corrosion current density.
Radiation-thermal decomposition of nitric and acetic acids in the aqueous nitrate solution
International Nuclear Information System (INIS)
Kinetics of radiation, thermal and radiation-thermal decompositions of nitric and acetic acid mixture was investigated in aqueous sodium nitrate solution in homogeneous conditions as well as by interaction of solid phase as sand rock. Temperature dependences of rate of radiation, thermal and radiation-thermal decompositions of the acids were calculated using experimental data. Resulting solutions make possible the calculation of acid decomposition dynamics accounting conditions of underground radioactive waste disposals
Haroon Jamshaid Qazi; Hamid Majeed; Waseem Safdar; John Antoniou; Zhong Fang
2015-01-01
Microencapsulation is a promising technique to retain the physical attributes of nanoemulsions and to overcome the oxidation of bioactives that become more available to aqueous phase during emulsification. Purity Gum Ultra (PGU) and Hi-CAP 100 (HiCap) emulsified nanoemulsions of Clove Oil (CO) co-encapsulated with Canola oil (CA) and Medium Chain Triglyceride (MCT) (5:5% v/v CO:CA and CO:MCT) were prepared through high pressure homogenization. Microencapsulation of nanoemulsions was performed...
... Proprietary Names (PDF - 146KB) Draft Guidance for Industry: Best Practices in Developing Proprietary Names for Drugs (PDF - 279KB) ... or (301) 796-3400 druginfo@fda.hhs.gov Human Drug ... in Medication Errors Resources for You Agency for Healthcare Research and Quality: ...
International Nuclear Information System (INIS)
This work reports the preparation, characterization and study of the ion exchange behavior of hydrous niobium oxide prepared by a homogeneous precipitation method. The precipitating agent was obtained in aqueous solution by thermal decomposition of urea or ammonium carbonate. The compounds were chemically and physically characterized by X-ray diffractometry, thermal analysis (TG/DTG), surface area measurements and ion exchange behavior with sodium. The materials prepared with ammonium carbonate presented a higher degree of crystallinity and better ion exchange capacity with sodium than materials prepared with urea. In the homogeneous precipitation method, materials were obtained with specific surface area of 123 - 224 m2 g-1. A variation of the preparation process produced hydrous niobium oxide with a different degree of hydration and specific surface area. This provided materials with different physico-chemical properties. (author)
Feeding premature infants banked human milk homogenized by ultrasonic treatment.
Rayol, M R; Martinez, F E; Jorge, S M; Gonçalves, A L; Desai, I D
1993-12-01
Premature neonates fed ultrasonically homogenized human milk had better weight gain and triceps skin-fold thickness than did a control group given untreated human milk (p tube feeding (p Ultrasonic homogenization of human milk appears to minimize loss of fat and thus allows better growth of premature infants. PMID:8229535
Non-linear waves in heterogeneous elastic rods via homogenization
De Luna, Manuel Quezada
2012-03-01
We consider the propagation of a planar loop on a heterogeneous elastic rod with a periodic microstructure consisting of two alternating homogeneous regions with different material properties. The analysis is carried out using a second-order homogenization theory based on a multiple scale asymptotic expansion. © 2011 Elsevier Ltd. All rights reserved.
Holomorphic maps from rational homogeneous spaces onto projective manifolds
Lau, Chihin
2008-01-01
Answering a problem raised by Lazarsfeld, Hwang and Mok proved that a surjective holomorphic map from a rational homogeneous space of Picard number 1 onto projective manifold different from projective space must be a biholomorphism. THe aim of this paper is to generalized this result to irreducible rational homogeneous space of higher Picard number.
On the classification of quasi-homogeneous curves
Câmara, Leonardo Meireles
2010-01-01
We apply techniques of Holomorphic Foliations in the description of the analytic invariants associated to germs of quasi-homogeneous curves in $(\\mathbb{C}^2,0)$. As a consequence we obtain an effective method to determine whether two quasi-homogeneous curves are analytically equivalent.
Rhodium trichloride as a homogeneous catalyst for isotopic hydrogen exchange
International Nuclear Information System (INIS)
The use of rhodium trichloride as a homogeneous catalyst for the exchange of aromatic compounds and alkanes is described; comparison of the results with corresponding data from heterogeneous rhodium metal and other homogeneous systems, e.g., platinum and iridium, supports the proposal that specific type of π-complex mechanisms are common to all such exchange systems. (author)
Homogeneous Buchberger algorithms and Sullivant's computational commutative algebra challenge
DEFF Research Database (Denmark)
Lauritzen, Niels
2005-01-01
We give a variant of the homogeneous Buchberger algorithm for positively graded lattice ideals. Using this algorithm we solve the Sullivant computational commutative algebra challenge.......We give a variant of the homogeneous Buchberger algorithm for positively graded lattice ideals. Using this algorithm we solve the Sullivant computational commutative algebra challenge....
Thermal concentrator homogenized with solar-shaped mantle
Petiteau, David; Bellieud, Michel; Zerrad, Myriam; Amra, Claude
2015-01-01
We propose solar-shaped thermal concentrators designed with orthoradial layers and obtained in practice through the homogenization of an ideal thermal concentrator. Considering the spectral regime of the heat equation, we quantitatively evaluate at different pulsations the effectiveness of the homogenized concentrators by comparing the thermal flux existing in an ideal concentrator and the thermal flux in an homogenized concentrator. Dependence on the pulsation is shown to be negligible and plotting the effectiveness of the homogenized concentrators as a function of the number of orthoradial layers $N$, we determine the number of layers needed to achieve a certain effectiveness. Significantly high numbers $N$(ranging from a hundred to tens of thousands layers) are found highlighting the fact that achieving high effectiveness demands a high level of engineering of the homogenized concentrator.
Scale-dependent homogeneity measures for causal dynamical triangulations
Cooperman, Joshua H
2014-01-01
I propose two scale-dependent measures of the homogeneity of the quantum geometry determined by an ensemble of causal triangulations. The first measure is volumetric, probing the growth of volume with graph geodesic distance. The second measure is spectral, probing the return probability of a random walk with diffusion time. Both of these measures, particularly the first, are closely related to those used to assess the homogeneity of our own universe on the basis of galaxy redshift surveys. I employ these measures to quantify the quantum spacetime homogeneity as well as the temporal evolution of quantum spatial homogeneity of ensembles of causal triangulations in the well-known physical phase. According to these measures, the quantum spacetime geometry exhibits some degree of inhomogeneity on sufficiently small scales and a high degree of homogeneity on sufficiently large scales. This inhomogeneity appears unrelated to the phenomenon of dynamical dimensional reduction. I also uncover evidence for power-law sc...
Fibrations and globalizations of compact homogeneous CR-manifolds
International Nuclear Information System (INIS)
Fibration methods which were previously used for complex homogeneous spaces and CR-homogeneous spaces of special types [1]-[4] are developed in a general framework. These include the g-anticanonical fibration in the CR-setting, which reduces certain considerations to the compact projective algebraic case, where a Borel-Remmert type splitting theorem is proved. This leads to a reduction to spaces homogeneous under actions of compact Lie groups. General globalization theorems are proved which enable one to regard a homogeneous CR-manifold as an orbit of a real Lie group in a complex homogeneous space of a complex Lie group. In the special case of CR-codimension at most two, precise classification results are proved and are applied to show that in most cases there exists such a globalization
Directory of Open Access Journals (Sweden)
Tabatabaeian Khalil
2012-01-01
Full Text Available The one-pot domino Knoevenagel-type condensation/Michael reaction of aromatic, heteroaromatic and aliphatic aldehydes with 4-hydroxycoumarin in aqueous media in the presence of ruthenium salt as homogeneous catalyst was investigated. It was found that 5 mol% of RuCl3.nH2O catalyzes biscoumarin synthesis in high yields (70-95% under optimised, mild, green and environmentally benign reaction conditions in short times (25-35min.
Aqueous Geochemistry at High Pressures and High Temperatures
Energy Technology Data Exchange (ETDEWEB)
Bass, Jay D. [Univ. of Illinois, Urbana-Champaign, IL (United States)
2015-05-21
This project is aimed at experimental characterization of the sound velocities, equations of state (EOS), and derived physical and chemical properties of aqueous solutions and carbon dioxide at extreme pressure and temperature conditions relevant to processes occurring in the interior of the Earth. Chemical transport, phase changes (including melting), fluid-solid reactions, and formation of magmatic liquids at convergent plat boundaries are a key motivation for this project. Research in this area has long been limited by the extreme experimental challenges and lack of data under the appropriate pressure-temperature (P-T) conditions. The vast majority of studies of aqueous geochemistry relevant to terrestrial problems of fluid-rock interactions have been conducted at 0.3 GPa or less, and the widely used Helgeson-Kirkham-Flowers equation of state for aqueous species is applicable only at ~ < 0.5 GPa. These limits are unfortunate because fluid flow and reactions plays a central role in many deeper environments. Recent efforts including our own, have resulted in new experimental techniques that now make it possible to investigate properties of homogeneous and heterogeneous equilibria involving aqueous species and minerals over a much broader range of pressure and temperature appropriate for deep crustal and upper mantle processes involving water-rich fluids. We carried out 1) Brillouin scattering measurements of the equations of state and molar volume of water and carbon dioxide to over 10 GPa and 870K using precise resistance heating of samples under pressure in the diamond anvil cell, and 2) the phase diagrams of the water and CO2, and 3) Exploring new experimental approaches, including CO2 laser heating of samples in a diamond cell, to measurements of sound velocities, EOS, and phase relations by Brillouin scattering to far greater pressures and temperatures.
Aqueous coordination complexes of neptunium
International Nuclear Information System (INIS)
Thecomplex formation constants, obtained by different methods, for the complexing of neptunium, in different oxidation states, in aqueous solutions, with several organic and inorganic ligands, have been critically reviewed. The values for the thermodynamic parameters associated with the complex formation, wherever available, are also presented. (author)
Aqueous systems and geothermal energy
International Nuclear Information System (INIS)
Significant unpublished results reported include: osmotic coefficients of KCl solutions vs. molality at 109 to 2010C; cadmium ion diffusivities in CaCl2 hydrous melts; a x-ray diffraction study of the uranyl complex in water; solubility of amorphous silica in aqueous NaNO3 solutions at 100 to 3000C; and corrosion of carbon steel by geothermal brine
Cui, Bo; Feng, Lei; Wang, Chunxin; Yang, Dongsheng; Yu, Manli; Zeng, Zhanghua; Wang, Yan; Sun, Changjiao; Zhao, Xiang; Cui, Haixin
2016-01-01
Poorly water-soluble compounds are difficult to develop as pesticide products and face great challenges in water-based and environmentally friendly formulation development. In this study, high pressure homogenization combined with lyophilization was adopted to prepare the solid nanodispersions of chlorantraniliprole with poor solubility and high melting point. The mean particle sizes of the solid nanodispersions with different pesticide contents were all less than 75 nm, even when the content was up to 91.5%. For the 2.5% chlorantraniliprole solid nanodispersion with the mean particle size of 29 nm, the suspensibility and wetting time in water were 97.32% and 13 s, respectively. The re-dispersibility and wettability were superior to those of conventional water dispersible granules. The retention on the rice leaf of 18.7 mg/cm2 was 1.5 and 3 times that of commercial aqueous suspension concentrate and pure water. The bioassay result to diamondback moths indicated that the toxicity of the solid nanodispersion was 3.3 and 2.8 times that of technical and aqueous suspension concentrate, respectively. Moreover, the solid nanodispersion has the advantages of total avoidance of organic solvents, significant reduction of surfactants and feasibility of obtaining high concentration nanoformulations. The solid nanodispersion is an attractive candidate for improving pesticide solubility and efficacy, and its application in crop production will reduce both residues in food and environmental pollution of pesticide. PMID:27500828
Homogeneous liquid-liquid extraction of uranium (VI) using tri-n-octylphosphine oxide
International Nuclear Information System (INIS)
A simple and efficient method for the selective separation and preconcentration of uranium (VI) using homogeneous liquid-liquid extraction was developed. Tri-n-octylphosphine oxide (TOPO) and tri-n-butylphosphate (TBP) were investigated as complexing ligands, and perfluorooctanoate ion (PFOA-) was applied as a phase separator agent under strongly acidic conditions. Under the optimal conditions ([PFOA-] = 1.7 x 10-3M, [TOPO] 5.4 x 10-4 M, [HNO3] = 0.3 M, [acetone] = 3.2% v/v) 10 μg of uranium in 40 ml aqueous phase could be extracted quantitatively into 8 μl of the sedimented phase. The maximum concentration factor was 5000-fold. However, an effort for the quantitative extraction using TBP was inefficient and the percent recovery was at most 56.7. The influence of the type and concentration of acid solution, optimum amount of the ligand, type and volume of the organic solvent, concentration of PFOA, volume of the aqueous sample and effect of different diverse ions on the extraction and determination of uranium (VI) were investigated. The proposed method was applied to the extraction and determination of uranium (VI) in natural water samples. (author)
Cui, Bo; Feng, Lei; Wang, Chunxin; Yang, Dongsheng; Yu, Manli; Zeng, Zhanghua; Wang, Yan; Sun, Changjiao; Zhao, Xiang; Cui, Haixin
2016-01-01
Poorly water-soluble compounds are difficult to develop as pesticide products and face great challenges in water-based and environmentally friendly formulation development. In this study, high pressure homogenization combined with lyophilization was adopted to prepare the solid nanodispersions of chlorantraniliprole with poor solubility and high melting point. The mean particle sizes of the solid nanodispersions with different pesticide contents were all less than 75 nm, even when the content was up to 91.5%. For the 2.5% chlorantraniliprole solid nanodispersion with the mean particle size of 29 nm, the suspensibility and wetting time in water were 97.32% and 13 s, respectively. The re-dispersibility and wettability were superior to those of conventional water dispersible granules. The retention on the rice leaf of 18.7 mg/cm2 was 1.5 and 3 times that of commercial aqueous suspension concentrate and pure water. The bioassay result to diamondback moths indicated that the toxicity of the solid nanodispersion was 3.3 and 2.8 times that of technical and aqueous suspension concentrate, respectively. Moreover, the solid nanodispersion has the advantages of total avoidance of organic solvents, significant reduction of surfactants and feasibility of obtaining high concentration nanoformulations. The solid nanodispersion is an attractive candidate for improving pesticide solubility and efficacy, and its application in crop production will reduce both residues in food and environmental pollution of pesticide. PMID:27500828
Antinociceptive activity of Mentha piperita leaf aqueous extract in mice
Directory of Open Access Journals (Sweden)
Yousef A. Taher
2012-03-01
Full Text Available Mentha piperita L. (Labiatae is an herbaceous plant, used in folk medicine for the treatment of several medical disorders.In the present study, the aqueous extract of Mentha piperita leaf, at the i.p doses 200 and 400 mg/kg, showed significant analgesic effects against both acetic acid-induced writhing and hot plate-induced thermal stimulation in mice, with protection values of 51.79% and 20.21% respectively. On the contrary, the Mentha piperita leaf aqueous extract did not exhibit anti-inflammatory activity against carrageenan induced paw oedema.These findings indicate that Mentha piperita has a potential analgesic effect that may possibly have mediated centrally and peripherally, as well as providing a pharmacological evidence for its traditional use as a pain reliever.
Controversies in Glaucoma: Current Medical Treatment and Drug Development.
Bucolo, Claudio; Platania, Chiara Bianca Maria; Reibaldi, Michele; Bonfiglio, Vincenza; Longo, Antonio; Salomone, Salvatore; Drago, Filippo
2015-01-01
Elevated eye pressure is the main risk factor for glaucoma; intraocular pressure rises when the ratio between aqueous humor formation (inflow) and its outflow is unbalanced. Currently, the main goal of medical treatment is the reduction of intraocular pressure. Five main classes of topical drugs are available; they include betablockers, carbonic anhydrase inhibitors, prostaglandin derivatives, sympathomimetics and miotics. Beta-blockers and carbonic anhydrase inhibitors slow the formation of aqueous humor and may be considered as "inflow" drugs; the other three classes reduce the resistance to the drainage of aqueous humor and may be considered as "outflow" drugs. Despite the variety of drugs accessible in the market, there is a real need for ophthalmologists to have more potent medications for this disease. This review focuses on medical treatment of glaucoma with particular attention to novel molecules in pre-clinical or clinical development. PMID:26350532
Townsend, David W
1996-01-01
Since the introduction of the X-ray scanner into radiology almost 25 years ago, non-invasive imaging has become firmly established as an essential tool in the diagnosis of disease. Fully three-dimensional imaging of internal organs is now possible, b and for studies which explore the functional status of the body. Powerful techniques to correlate anatomy and function are available, and scanners which combine anatomical and functional imaging in a single device are under development. Such techniques have been made possible through r ecent technological and mathematical advances. This series of lectures will review both the physical basis of medical imaging techniques using X-rays, gamma and positron emitting radiosiotopes, and nuclear magnetic resonance, and the mathematical methods used to reconstruct three-dimentional distributions from projection data. The lectures will trace the development of medical imaging from simple radiographs to the present-day non-invasive measurement of in vivo biochemistry. They ...
Reed, Christie M
2008-11-01
Searches of the literature or Internet using the term "medical tourism" produce two sets of articles: travel for the purpose of delivering health care or travel for the purpose of seeking health care. The first usage primarily appears in the medical literature and is beyond the scope of this article, which focuses on travel to seek health care. Still, there are some aspects these two topics have in common: both are affected by ease and speed of international travel and communication associated with globalization, and both raise questions about continuity of care as well as issues related to cultural, language, and legal differences; both also raise questions about ethics. This article describes some of the motivating factors, contributing elements, and challenges in elucidating trends, as well as implications for clinicians who provide pretravel advice and those who care for ill returning travelers. PMID:19061760
DEFF Research Database (Denmark)
Grembi, Veronica
2014-01-01
MM first came to the attention of policy makers primarily in the USA where, from the 1970s, healthcare providers denounced problems in getting insurance for medical liability, pointing out to a crisis in the MM insurance market (Sage WM (2003) Understanding the first malpractice crisis of the 21th....../or its affordability, the withdrawal from the MM insurance of commercial insurers, the growth of MM public insurance or self-insurance solutions, the choice of no-fault rather than negligence liability, the adoption of enterprise liability for hospitals, the concerns for defensive medicine, and the...... in the last decades also among European countries (Hospitals of the European Union (HOPE) (2004) Insurance and malpractice, final report. Brussels, www.hope.be; OECD (2006) Medical malpractice, insurance and coverage options, policy issues in insurance n.11; EC (European Commission, D.G. Sanco) (2006...
Energy Technology Data Exchange (ETDEWEB)
Sarkar, Amrita; Kedia, Niraja [Department of Chemical Sciences, Indian Institute of Science Education and Research, Kolkata, Mohanpur Campus, BCKV Main P.O., Mohanpur 741252, Nadia, WB (India); Bagchi, Sanjib, E-mail: bsanjibb@yahoo.com [Department of Chemistry and Biochemistry, Presidency University, 86/1 College Street, Kolkata 700073 (India)
2014-07-01
A new water soluble donor–acceptor dye, sodium 4-(methyl((1E,3E)-3-(1-oxo-1H-inden-2(3H)-ylidene)prop-1-enyl)amino) benzoate (DN3) has been synthesized. Optical response of the solvatochromic dye (DN3) has been studied in various homogeneous (neat and mixed binary solvents) and heterogeneous (SDS and CTAB homomicelle and β-cyclodextrin nanocavity) media. To get information regarding the change in the solvation interaction of the dye with the alteration in its microenvironment in different media, the photophysical properties of the dye have been monitored in various media using steady state and time resolved spectral analysis. Results obtained for mixed binary solvents containing water indicate that the solute is preferentially solvated by one of the component solvents and solvent–solvent interactions are also important in determining the preference. Effect of variation of pH in aqueous medium on the spectroscopic parameters of the dye has been studied and its pKa has been estimated. Studies in homomicelles (SDS and CTAB) reveal that the dye distributes itself between the aqueous and the micellar phase and the values of distribution coefficient have been estimated from the fluorescence parameters. The dye is encapsulated in β-cyclodextrin nanocavity and a 1:2 dye-β-cyclodextrin host–guest interaction is indicated. Semi-empirical quantum chemical calculations have been carried out to support the experimental results. - Highlights: • A water soluble fluorescent dye has been synthesized and studied in various media. • The dye is sensitive towards changes in micropolarity and pH of the medium. • Study in mixed binary solvent system indicates preferential solvation of the dye. • Stronger interaction of the dye is indicated with CTAB micelles compared to SDS. • Study in aqueous β-CD medium reveals favorable 1:2 binding of the dye with β-CD.
Characterizing Fullerene Nanoparticles in Aqueous Suspensions
Studies have indicated that fullerenes can form stable colloidal suspensions in water when introduced to the aqueous phase through solvent exchange, sonication, or extended mixing. The colloidal suspensions created using these techniques have effective aqueous phase concentratio...
Kreel, L.
1991-01-01
There is now a wide choice of medical imaging to show both focal and diffuse pathologies in various organs. Conventional radiology with plain films, fluoroscopy and contrast medium have many advantages, being readily available with low-cost apparatus and a familiarity that almost leads to contempt. The use of plain films in chest disease and in trauma does not need emphasizing, yet there are still too many occasions when the answer obtainable from a plain radiograph has not been available. Th...
International Nuclear Information System (INIS)
Within Brookhaven National Laboratory, the life sciences program is carried out under two departments, the Medical Department and the Biological Department. The Medical Research Center contains three major divisions: the Hospital, the Research Laboratories, and the Occupational Medicine Clinic. The hospital, which is devoted entirely to research patients, supports clinical studies in: pulmonary diseases; neuropsychiatric disorders; hematological diseases (e.g., chronic lymphocytic leukemia); cardiopulmonary disorders; hepatobiliary dysfunction; cancer of various types; toxicological problems; bone and mineral metabolism; and dietary and nutritional disorders. Research efforts are also made to improve therapeutic measures for disease: brain tumor therapy through boron capture of epithermal neutrons, and proton beam irradiation; extracorporeal irradiation of blood in leukemia; iron chelator efficacy in thalassemia; and nonsurgical treatment of ocular melanoma. Early diagnoses and studies of the mechanism of disease are approached through medical applications of nuclear technology, including positron emission tomography. Work carried out within the Biological Department includes: biological structure determination, molecular genetics, DNA repair and plant sciences. A large part of the research is devoted to understanding how biological systems work. Central to this aim is the study of DNA. This includes effects of damage by physical and chemical agents, gene cloning of bacteria and plants and effects of low doses of radiation and other energy derived hazards
Boccara, A. Claude; Mordon, Serge
2015-10-01
In re-listening to the lectures of Charles Townes shortly after the invention of the laser (e.g., in the Boston Science Museum), one can already have a realistic vision of the potentialities of this new tool in the field of medical therapy, as evidenced by the use of the laser in ophthalmology to cure retinal detachment in the 1960's. Since then, applications have flourished in the domain of therapy. We will thus illustrate here only some of the main fields of application of medical lasers. On the opposite, the use of lasers in medical imaging is, with one exception in ophthalmology, still at the development level. It is becoming a diagnostic tool in addition to high performance imaging facilities that are often very expensive (such as CT scan, Magnetic Resonance Imaging (MRI) and nuclear imaging). Even if progress is sometimes slow, one can now image with light inside the human body, in spite of the strong scattering of light by tissues, in the same way as a pathologist sees surgical specimens.
Reduction of pantethine in rabbit ocular lens homogenate.
Fisher, D H; Szulc, M E
1997-02-01
In several animal models, preliminary studies have indicated that pantethine may inhibit cataract formation. Therefore, preclinical trials need to be conducted to study the pharmacology of pantethine in the ocular lens and to establish its efficacy. Since pantethine, which is a disulfide, can undergo a variety of chemical modifications such as reduction and formation of mixed disulfides, a detailed study was first conducted to determine the stability of pantethine in rabbit lens homogenate. A knowledge of the stability of pantethine in lens homogenate was necessary to establish if pantethine could be metabolized in the time it takes to harvest and homogenize a lens. The results of this study will be used to establish a protocol for harvesting and homogenizing lens samples. Pantethine (100 microM) is completely reduced to pantetheine in rabbit lens homogenate in about 16 min. About 1.5% of the pantethine added to lens homogenate forms a mixed disulfide with lens proteins, and the remainder is found in the supernatant. The supernatant pantethine concentration decreases exponentially as a function of time, and the terminal half-life for this process is 3.3 min. The free supernatant pantetheine concentration increases in pseudo first order manner as a function of time with a rate constant of 4.3 min. Pantethinase activity is not significant, because the free supernatant pantetheine concentration did not decrease. The exact mechanism of pantethine reduction in rabbit lens homogenate remains to be determined. PMID:9127277
Homogenization and improvement in energy dissipation of nonlinear composites
Verma, Luv; Sivakumar, Srinivasan M.; Vedantam, S.
2016-04-01
Due to their high strength to weight and stiffness to weight ratio, there is a huge shift towards the composite materials from the conventional metals, but composites have poor damage resistance in the transverse direction. Undergoing impact loads, they can fail in wide variety of modes which severely reduces the structural integrity of the component. This paper deals with the homogenization of glass-fibers and epoxy composite with a material introduced as an inelastic inclusion. This nonlinearity is being modelled by kinematic hardening procedure and homogenization is done by one of the mean field homogenization technique known as Mori-Tanaka method. The homogenization process consider two phases, one is the matrix and another is the inelastic inclusion, thus glass-fibers and epoxy are two phases which can be considered as one phase and act as a matrix while homogenizing non-linear composite. Homogenization results have been compared to the matrix at volume fraction zero of the inelastic inclusions and to the inelastic material at volume fraction one. After homogenization, increase of the energy dissipation into the composite due to addition of inelastic material and effects onto the same by changing the properties of the matrix material have been discussed.
At tank Low Activity Feed Homogeneity Analysis Verification
Energy Technology Data Exchange (ETDEWEB)
DOUGLAS, J.G.
2000-09-28
This report evaluates the merit of selecting sodium, aluminum, and cesium-137 as analytes to indicate homogeneity of soluble species in low-activity waste (LAW) feed and recommends possible analytes and physical properties that could serve as rapid screening indicators for LAW feed homogeneity. The three analytes are adequate as screening indicators of soluble species homogeneity for tank waste when a mixing pump is used to thoroughly mix the waste in the waste feed staging tank and when all dissolved species are present at concentrations well below their solubility limits. If either of these conditions is violated, then the three indicators may not be sufficiently chemically representative of other waste constituents to reliably indicate homogeneity in the feed supernatant. Additional homogeneity indicators that should be considered are anions such as fluoride, sulfate, and phosphate, total organic carbon/total inorganic carbon, and total alpha to estimate the transuranic species. Physical property measurements such as gamma profiling, conductivity, specific gravity, and total suspended solids are recommended as possible at-tank methods for indicating homogeneity. Indicators of LAW feed homogeneity are needed to reduce the U.S. Department of Energy, Office of River Protection (ORP) Program's contractual risk by assuring that the waste feed is within the contractual composition and can be supplied to the waste treatment plant within the schedule requirements.
At-tank Low-Activity Feed Homogeneity Analysis Verification
International Nuclear Information System (INIS)
This report evaluates the merit of selecting sodium, aluminum, and cesium-137 as analytes to indicate homogeneity of soluble species in low-activity waste (LAW) feed and recommends possible analytes and physical properties that could serve as rapid screening indicators for LAW feed homogeneity. The three analytes are adequate as screening indicators of soluble species homogeneity for tank waste when a mixing pump is used to thoroughly mix the waste in the waste feed staging tank and when all dissolved species are present at concentrations well below their solubility limits. If either of these conditions is violated, then the three indicators may not be sufficiently chemically representative of other waste constituents to reliably indicate homogeneity in the feed supernatant. Additional homogeneity indicators that should be considered are anions such as fluoride, sulfate, and phosphate, total organic carbon/total inorganic carbon, and total alpha to estimate the transuranic species. Physical property measurements such as gamma profiling, conductivity, specific gravity, and total suspended solids are recommended as possible at-tank methods for indicating homogeneity. Indicators of LAW feed homogeneity are needed to reduce the U.S. Department of Energy, Office of River Protection (ORP) Program's contractual risk by assuring that the waste feed is within the contractual composition and can be supplied to the waste treatment plant within the schedule requirements
Peripheral nerve magnetic stimulation: influence of tissue non-homogeneity
Directory of Open Access Journals (Sweden)
Papazov Sava P
2003-12-01
Full Text Available Abstract Background Peripheral nerves are situated in a highly non-homogeneous environment, including muscles, bones, blood vessels, etc. Time-varying magnetic field stimulation of the median and ulnar nerves in the carpal region is studied, with special consideration of the influence of non-homogeneities. Methods A detailed three-dimensional finite element model (FEM of the anatomy of the wrist region was built to assess the induced currents distribution by external magnetic stimulation. The electromagnetic field distribution in the non-homogeneous domain was defined as an internal Dirichlet problem using the finite element method. The boundary conditions were obtained by analysis of the vector potential field excited by external current-driven coils. Results The results include evaluation and graphical representation of the induced current field distribution at various stimulation coil positions. Comparative study for the real non-homogeneous structure with anisotropic conductivities of the tissues and a mock homogeneous media is also presented. The possibility of achieving selective stimulation of either of the two nerves is assessed. Conclusion The model developed could be useful in theoretical prediction of the current distribution in the nerves during diagnostic stimulation and therapeutic procedures involving electromagnetic excitation. The errors in applying homogeneous domain modeling rather than real non-homogeneous biological structures are demonstrated. The practical implications of the applied approach are valid for any arbitrary weakly conductive medium.
Monte Carlo simulation of near-infrared light propagation through homogeneous mixed media.
Maughan, Nichole M; Moody, Joseph W; Miller, David R
2013-10-01
ABSTRACT. Noninvasive blood analysis devices that can measure levels of small constituents of blood are of interest in the medical community. An important step in creating these devices is to understand the interaction of photons with human tissue in increasingly greater physiological detail. Models based on layered biological materials give excellent results for many applications but may not be as accurate as needed when those materials are finely intertwined to the point of resembling a homogeneous mixture. To explore the ramifications of treating materials as layers versus a mixture, we have modeled, using a Monte Carlo technique, the interaction of photons through epidermis, blood, and water arranged both in layers and in a homogeneous blend. We confirm the expected linear relation between photon attenuation and material volumetric percentage in two-layer models. However, when the materials are homogeneously mixed together and volumetric percentage is replaced with interaction volume percentage, this relationship becomes nonlinear. These nonlinearities become significant when the values of the interaction coefficient, μt, differ by an order of magnitude or more. PMID:24145661
Analyses of beyond design basis accident homogeneous boron dilution scenarios
Energy Technology Data Exchange (ETDEWEB)
Kereszturi, Andras; Hegyi, Gyoergy; Maraczy, Csaba; Trosztel, Istvan; Tota, Adam [Hungarian Academy of Sciences, Centre for Energy Research, Budapest (Hungary); Karsa, Zoltan [NUBIKI Nuclear Safety Research Institute, Ltd., Budapest (Hungary)
2015-09-15
Homogeneous boron dilution scenarios in a VVER-440 reactor were analyzed using the coupled KIKO3D-ATHLET code. The scenarios are named ''homogeneous'' because of the very slow dilution caused by a rupture in the heat exchanger of the makeup system. Without the presented analyses, a significant contribution of the homogeneous boron dilution to the Core Damage Frequency (CDF) had to be assumed in the Probabilistic Safety Analyses (PSA). According to the combined results of the presented deterministic and probabilistic analyses, the final conclusion is that boron dilution transients don't give significant contribution to the CDF for the investigated VVER-440 NPP.
Locally $G$-homogeneous Busemann $G$-spaces
Berestovskiĭ, V N; Repovš, D; 10.1016/j.difgeo.2011.03.001
2011-01-01
We present short proofs of all known topological properties of general Busemann $G$-spaces (at present no other property is known for dimensions more than four). We prove that all small metric spheres in locally $G$-homogeneous Busemann $G$-spaces are homeomorphic and strongly topologically homogeneous. This is a key result in the context of the classical Busemann conjecture concerning the characterization of topological manifolds, which asserts that every $n$-dimensional Busemann $G$-space is a topological $n$-manifold. We also prove that every Busemann $G$-space which is uniformly locally $G$-homogeneous on an orbal subset must be finite-dimensional.
Homogenization and structural topology optimization theory, practice and software
Hassani, Behrooz
1999-01-01
Structural topology optimization is a fast growing field that is finding numerous applications in automotive, aerospace and mechanical design processes. Homogenization is a mathematical theory with applications in several engineering problems that are governed by partial differential equations with rapidly oscillating coefficients Homogenization and Structural Topology Optimization brings the two concepts together and successfully bridges the previously overlooked gap between the mathematical theory and the practical implementation of the homogenization method. The book is presented in a unique self-teaching style that includes numerous illustrative examples, figures and detailed explanations of concepts. The text is divided into three parts which maintains the book's reader-friendly appeal.
The F-pure threshold of quasi-homogeneous polynomials
Müller, Susanne
2016-01-01
Inspired by the work of Bhatt and Singh (see: arXiv:1307.1171) we compute the $F$-pure threshold of quasi-homogeneous polynomials. We first consider the case of a curve given by a quasi-homogeneous polynomial $f$ in three variables $x,y,z$ of degree equal to the degree of $xyz$ and then we proceed with the general case of a Calabi-Yau hypersurface, i.e. a hypersurface given by a quasi-homogeneous polynomial $f$ in $n+1$ variables $x_0, \\ldots, x_n$ of degree equal to the degree of $x_0 \\cdots...
Synthetic and mechanistic prospects of homogeneous gold catalysis
Pankajakshan, Sreekumar
2009-01-01
a) The first chapter of this thesis manifests the exploration of homogeneous gold-catalyzed conversions of furan containing aryl-ynamides and ynol ethers. Enynes boast to be the most explored substrate structures in the realm of homogeneous gold catalysis, whereas the reactivity of ene-ynamides and ene-ynol ethers are much less explored till date.34, 45 Hashmi and co-workers recently reported the homogeneous gold-catalyzed synthesis of phenols from furan containing ynamides/ynol ethers.45e Th...
An iterative homogenization technique that preserves assembly core exchanges
Energy Technology Data Exchange (ETDEWEB)
Mondot, Ph. [Electricite de France, Recherche et Developement, SINETICS, 92 - Clamart (France); Sanchez, R. [CEA Saclay, Direction des Etudes Nucleaires, Service Etude des Reacteurs et de Modelisations Avancees, 91 - Gilf sur Yvette (France)
2003-07-01
A new interactive homogenization procedure for reactor core calculations is proposed that requires iterative transport assembly and diffusion core calculations. At each iteration the transport solution of every assembly type is used to produce homogenized cross sections for the core calculation. The converged solution gives assembly fine multigroup transport fluxes that preserve macro-group assembly exchanges in the core. This homogenization avoids the periodic lattice-leakage model approximation and gives detailed assembly transport fluxes without need of an approximated flux reconstruction. Preliminary results are given for a one-dimensional core model. (authors)
Analyses of beyond design basis accident homogeneous boron dilution scenarios
International Nuclear Information System (INIS)
Homogeneous boron dilution scenarios in a VVER-440 reactor were analyzed using the coupled KIKO3D-ATHLET code. The scenarios are named ''homogeneous'' because of the very slow dilution caused by a rupture in the heat exchanger of the makeup system. Without the presented analyses, a significant contribution of the homogeneous boron dilution to the Core Damage Frequency (CDF) had to be assumed in the Probabilistic Safety Analyses (PSA). According to the combined results of the presented deterministic and probabilistic analyses, the final conclusion is that boron dilution transients don't give significant contribution to the CDF for the investigated VVER-440 NPP.
Kanno, H.; Kajiwara, K.; Miyata, K.
2010-05-01
Supercooling behavior of aqueous dimethylsulfoxide (DMSO) solution was investigated as a function of DMSO concentration and at high pressures. A linear relationship was observed for TH (homogeneous ice nucleation temperature) and Tm (melting temperature) for the supercooling of aqueous DMSO solution at normal pressure. Analysis of the DTA (differential thermal analysis) traces for homogeneous ice crystallization in the bottom region of the TH curve for a DMSO solution of R =20 (R: moles of water/moles of DMSO) at high pressures supported the contention that the second critical point (SCP) of liquid water should exist at Pc2=˜200 MPa and at Tc2<-100 °C (Pc2: pressure of SCP, Tc2: temperature of SCP). The presence of two TH peaks for DMSO solutions (R =15, 12, and 10) suggests that phase separation occurs in aqueous DMSO solution (R ≤15) at high pressures and low temperatures (<-90 °C). The pressure dependence of the two TH curves for DMSO solutions of R =10 and 12 indicates that the two phase-separated components in the DMSO solution of R =10 have different liquid water structures [LDL-like and HDL-like structures (LDL: low-density liquid water, HDL: high-density liquid water)] in the pressure range of 120-230 MPa.
Zeng, Qinghui; Li, Qin; Ji, Wenyu; Bin, Xue; Song, Jie
2016-05-01
With growing concerns about health issues worldwide, elegant sensors with high sensitivity and specificity for virus/antigens (Ag) detection are urgent to be developed. Homogeneous immunoassays (HIA) are an important technique with the advantages of small sample volumes requirement and pretreatment-free process. HIA are becoming more favorable for the medical diagnosis and disease surveillance than heterogeneous immunoassays. An important subset of HIA relies on the effect of fluorescence resonance energy transfer (FRET) via a donor-acceptor (D–A) platform, e.g., quantum dots (QDs) donor based FRET system. Being an excellent plasmonic material, silver triangular nanoplates (STNPs) have unique advantages in displaying surface plasmon resonance in the visible to near infrared spectral region, which make them a better acceptor for pairing with QDs in a FRET-based sensing system. However, the reported STNPs generally exhibited broad size distributions, which would greatly restrict their application as HIA acceptor for high detection sensitivity and specificity purpose. In this work, uniform STNPs and red-emitting QDs are firstly applied to construct FRET nanoplatform in the advanced HIA and further be exploited for analyzing virus Ag. The uniform STNPs/QDs nanoplatform based medical sensor provides a straightforward and highly sensitive method for Ag analysis in homogeneous form.
Osipov, Y. M.; Syryamkin, V. I.; Osipov, O. Y.
2015-11-01
The first part of the article presentsdevices of rehabilitation electromechatronics.As a research work, the author's team has performed sketch and technical developments on this subject, which are protected by patents of the Russian Federation. The second part providesan overview of medical robotic surgery, which is ideal for imperfections removing.It also describes capabilities of the author's team in development of active driveline based "iron" hands.Scalpels never tremble in the iron hands, which are not afraid of the aftershocks and never get tired.They can perform operations during not less than 48 consecutive hours.
Troccaz, Jocelyne
2013-01-01
In this book, we present medical robotics, its evolution over the last 30 years in terms of architecture, design and control, and the main scientific and clinical contributions to the field. For more than two decades, robots have been part of hospitals and have progressively become a common tool for the clinician. Because this domain has now reached a certain level of maturity it seems important and useful to provide a state of the scientific, technological and clinical achievements and still open issues. This book describes the short history of the domain, its specificity and constraints, and
Sugimachi, Masaru; Sunagawa, Kenji
2006-02-01
Development of implantable medical nanodevices enables us continuous automatic treatment of patients from inside of their body. Bionic devices, interfacing with neural systems and substituting native functions, such as bionic pacemaker, bionic pressure controller are candidates to miniaturize. For such miniaturization, efforts to reduce size of power supply (e.g., biological fuel cell) and to establish reliable high-throughput, low power telecommunication (e.g., spread spectrum telecommunication) are required. Simple devices such as pacemakers would benefit from miniaturization by lowering invasion and by developing a new usage such as ventricular resynchronization. PMID:16454192
Smoking cessation - medications; Smokeless tobacco - medications; Medications for stopping tobacco ... Creating a plan to help you deal with smoking urges. Getting support from a doctor, counselor, or ...
Radiolysis of berberine or palmatine in aqueous solution
Energy Technology Data Exchange (ETDEWEB)
Marszalek, Milena [Institute of Applied Radiation Chemistry, Technical University of Lodz, Wroblewskiego 15, 93-590 Lodz (Poland); Wolszczak, Marian, E-mail: marianwo@mitr.p.lodz.p [Institute of Applied Radiation Chemistry, Technical University of Lodz, Wroblewskiego 15, 93-590 Lodz (Poland)
2011-01-15
The reactions of hydrated electron (e{sub aq}{sup -}), hydrogen atom (H{sup {center_dot}}) (reducing species) and Cl{sub 2}{sup {center_dot}}{sup -},Br{sub 2}{sup {center_dot}}{sup -},{sup {center_dot}}N{sub 3},{sup {center_dot}}OH radicals (oxidizing species) with berberine or palmatine in aqueous solution have been studied by steady-state and pulse radiolysis. The spectra of transient intermediates, leading to the final products, are presented. The rate constants of the reaction of e{sub aq}{sup -} and {sup {center_dot}}OH radical with both alkaloids in the homogenous solution and in the presence of DNA are reported. It is demonstrated that the primary products of the reaction of berberine and palmatine with e{sub aq}{sup -} and radicals generated during radiolysis are unstable and undergo further reactions.
Sweet aqueous solution for electrochemical synthesis of polypyrrole
Energy Technology Data Exchange (ETDEWEB)
Bazzaoui, M. [Faculdade de Engenharia, Departamento de Engenharia Quimica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal) and Faculdade de Engenharia, Departamento de Electrotecnica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal)]. E-mail: bazzaoui@fe.up.pt; Martins, J.I. [Faculdade de Engenharia, Departamento de Engenharia Quimica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal) and Faculdade de Engenharia, Departamento de Electrotecnica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal)]. E-mail: jipm@fe.up.pt; Costa, S.C. [Faculdade de Engenharia, Departamento de Engenharia Quimica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal); Bazzaoui, E.A. [Faculte des Sciences, Departement de Chimie, Universite Mohammed Ier, 60 000 Oujda (Morocco); Reis, T.C. [Faculdade de Engenharia, Departamento de Engenharia Quimica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal); Martins, L. [Faculdade de Engenharia, Departamento de Electrotecnica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal)
2006-02-25
The electrosynthesis of polypyrrole (PPy) has been achieved on aluminum electrode in aqueous medium of 0.1 M saccharin sodium salt and 0.5 M pyrrole. Scanning electron microscopy shows that the PPy coating obtained in galvanostatic and potentiostatic modes starts with small islands at weak applied potentials or current densities. Moreover, energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) reveal a good homogeneity of the film achieved in cyclic voltammetry during 10 cycles. The electrochemical impedance spectroscopy (EIS) results show that the coating decreases the polarization resistance of the aluminum electrode. The open circuit potential (OCP) and dc polarization measurements achieved in HCl and NaCl solutions displayed a large positive displacement of corrosion potential and a reduction of corrosion current in the case of PPy coating electrode in comparison with electrode bare.
Aqueous nitrate flowsheet optimization and enhancement using the ATLAS facility
International Nuclear Information System (INIS)
The Advanced Testing Line for Actinide Separations (ATLAS) is a pilot plant of all aqueous nitrate plutonium recovery and purification operations within the Los Alamos Plutonium Facility. The main unit operations include dissolution, anion exchange, precipitations, evaporation, calcination, and waste stream polishing. In the current political environment, the emphasis has been redirected from the traditional goal of recovering a pure plutonium product to that of generating ''clean'' effluents while placing the plutonium into a form suitable for long term storage. The ATLAS facility is uniquely suited to fulfill this new role in the development and demonstration of new or revisited technologies. This report summarizes recent work in equipment improvements to the batch dissolver, an evaluation of homogeneous hydroxide precipitations, a demonstration of nitric acid recycle, and the preparation of neptunium and plutonium standards
Thermoreversible (Ionic-Liquid-Based) Aqueous Biphasic Systems
Passos, Helena; Luís, Andreia; Coutinho, João A. P.; Freire, Mara G.
2016-02-01
The ability to induce reversible phase transitions between homogeneous solutions and biphasic liquid-liquid systems, at pre-defined and suitable operating temperatures, is of crucial relevance in the design of separation processes. Ionic-liquid-based aqueous biphasic systems (IL-based ABS) have demonstrated superior performance as alternative extraction platforms, and their thermoreversible behaviour is here disclosed by the use of protic ILs. The applicability of the temperature-induced phase switching is further demonstrated with the complete extraction of two value-added proteins, achieved in a single-step. It is shown that these temperature-induced mono(bi)phasic systems are significantly more versatile than classical liquid-liquid systems which are constrained by their critical temperatures. IL-based ABS allow to work in a wide range of temperatures and compositions which can be tailored to fit the requirements of a given separation process.
Commutators, paraproducts and BMO in non-homogeneous martingale settings
Treil, Sergei
2010-01-01
In this paper we investigate the relations between (martingale) BMO spaces, paraproducts and commutators in non-homogeneous martingale settings. Some new, and one might add unexpected, results are obtained. Some alternative proof of known results are also presented.
Homogeneous Water Nucleation in a Laminar Flow Diffusion Chamber
Czech Academy of Sciences Publication Activity Database
Manka, A.; Brus, David; Hyvärinen, A-P.; Lihavainen, H.; Wölk, J.; Strey, R.
-: -, 2009, T032A02. [European Aerosol Conference 2009. Karlsruhe (DE), 06.09.2009-11.09.2009] Institutional research plan: CEZ:AV0Z40720504 Keywords : homogeneous nucleation * water * nucleation rate Subject RIV: CF - Physical ; Theoretical Chemistry
Fractal Dimension as a measure of the scale of Homogeneity
Yadav, Jaswant K; Khandai, Nishikanta
2010-01-01
In the multi-fractal analysis of large scale matter distribution, the scale of transition to homogeneity is defined as the scale above which the fractal dimension of underlying point distribution is equal to the ambient dimension of the space in which points are distributed. With finite sized weakly clustered distribution of tracers obtained from galaxy redshift surveys it is difficult to achieve this equality. Recently we have defined the scale of homogeneity to be the scale above which the deviation of fractal dimension from the ambient dimension becomes smaller than the statistical dispersion. In this paper we use the relation between the fractal dimensions and the correlation function to compute the dispersion for any given model in the limit of weak clustering amplitude. We compare the deviation and dispersion for the LCDM model and discuss the implication of this comparison for the expected scale of homogeneity in the concordant model of cosmology. We estimate the upper limit to the scale of homogeneity...
DESTRUCTION CONDITIONS WHEN DITTING HOMOGENEOUS GROUND AND GROUND WITH INCLUSION
Nichke, V.; Demishkan, V.
2005-01-01
On the base of analyses strained state the strong a ground with inclusion, and take into account a bigger traction effort of a modern bulldozers, was shoved as destroyed a rocks ground, a ground with inclusion, homogeneous a ground.
Remarks on Homogeneous Al-Salam and Carlitz Polynomials
Jian-Ping Fang
2014-01-01
Several multilinear generating functions of the homogeneous Al-Salam and Carlitz polynomials are derived from q-operator. In addition, two interesting relationships of product of this kind of polynomials are obtained.
The integral intertwining operators and quantum homogeneous spaces
International Nuclear Information System (INIS)
The invariant partial differential equations in the quantum homogeneous spaces are considered. The Dirichlet problem is solved, and the q-analogue of the Cauchy-Segue formula for the unit ball is obtained. 7 refs
Metric tensors for homogeneous, isotropic, 5-dimensional pseudo riemannian models
Anchordoqui, Luis A.; Birman, Graciela S.
2012-01-01
In this paper westudy the metric tensor of a homogeneous, isotropic, 5-dimensional pseudo Riemannian space, solving the corresponding Einstein equations when the spatial component is flat, spherical or pseudo spherical
Homogenization of temperature field and temperature gradient field
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
The homogenization of temperature field and temperature gradient field are very important for many devices, systems and equipments, such as satellites and electronic devices. This paper discusses the distribution optimization of the limited high conductivity material with the simulated annealing algorithm to homogenize the temperature field in a two-dimensional heat conduction problem. At the same time, the temperature gradient field is homogenized with the bionic optimization method. The results show that the two optimization targets are consistent to some extent, while the bionic optimization method could save much computing time. In addition, there are threshold values for the amount of high conductivity material and the ratio of the high conductivity to the low conductivity beyond which further increasing these values brings very little improvement on the homogenization of temperature field and temperature gradient field.
Anisotropic clustering of inertial particles in homogeneous shear flow
Gualtieri, P.; Picano, F.; Casciola, C. M
2009-01-01
Recently, clustering of inertial particles in turbulence has been thoroughly analyzed for statistically homogeneous isotropic flows. Phenomenologically, spatial homogeneity of particles configurations is broken by the advection of a range of eddies determined by the Stokes relaxation time of the particles which results in a multi-scale distribution of local concentrations and voids. Much less is known concerning anisotropic flows. Here, by addressing direct numerical simulations (DNS) of a st...
Matrix-dependent multigrid-homogenization for diffusion problems
Energy Technology Data Exchange (ETDEWEB)
Knapek, S. [Institut fuer Informatik tu Muenchen (Germany)
1996-12-31
We present a method to approximately determine the effective diffusion coefficient on the coarse scale level of problems with strongly varying or discontinuous diffusion coefficients. It is based on techniques used also in multigrid, like Dendy`s matrix-dependent prolongations and the construction of coarse grid operators by means of the Galerkin approximation. In numerical experiments, we compare our multigrid-homogenization method with homogenization, renormalization and averaging approaches.
Homogeneous right coideal subalgebras of quantized enveloping algebras
Heckenberger, I.; Kolb, S
2011-01-01
For a quantized enveloping algebra of a complex semisimple Lie algebra with deformation parameter not a root of unity, we classify all homogeneous right coideal subalgebras. Any such right coideal subalgebra is determined uniquely by a triple consisting of two elements of the Weyl group and a subset of the set of simple roots satisfying some natural conditions. The essential ingredients of the proof are the Lusztig automorphisms and the classification of homogeneous right coideal subalgebras ...
High frequency homogenization for travelling waves in periodic media
Harutyunyan, Davit; Craster, Richard V.; Milton, Graeme W.
2016-01-01
We consider high frequency homogenization in periodic media for travelling waves of several different equations: the wave equation for scalar-valued waves such as acoustics; the wave equation for vector-valued waves such as electromagnetism and elasticity; and a system that encompasses the Schr{\\"o}dinger equation. This homogenization applies when the wavelength is of the order of the size of the medium periodicity cell. The travelling wave is assumed to be the sum of two waves: a modulated B...
A Wald test with enhanced selectivity properties in homogeneous environments
Liu, Weijian; Xie, Wenchong; Wang, Yongliang
2013-12-01
A Wald test with enhanced selectivity capabilities is proposed in homogeneous environments. At the design stage, we assume that the cell under test contains a noise-like interferer in addition to colored noise and possible signal of interest. We show that the Wald test is equivalent to a recently proposed Rao test. We also observe that this Rao/Wald test possesses constant false alarm rate property in homogeneous environments.
Catalysis at the Homogeneous-Heterogeneous Chemistry Interface
Institute of Scientific and Technical Information of China (English)
Howard; Alper
2007-01-01
1 Results Significant progress has been made in recent years in developing efficient, atom economical catalytic reactions of potential applicability to the pharmaceutical, petrochemical, and commodity chemical business sectors. In some cases, homogeneous catalytic processes offer advantages, but in others the use of heterogenized homogeneous catalysis provides a competitive advantage concerning recyclability and catalyst recovery. This presentation will consider new approaches to cyclization reactions a...
Persuasion: Reflections on Economics, Data and the 'Homogeneity Assumption'
Adam Fforde
2004-01-01
This paper discusses issues to do with the empirical basis of modern economics and points towards the need to look more closely at the ‘homogeneity assumption’ that underpins much economic theory. It argues that severe problems currently prevent economics from becoming more persuasive to both students of economics and those outside the discipline. The issue involves the management of disciplinary boundaries, and excessive use of the ‘homogeneity assumption.’ Three areas of concern are explore...
Recent advances in the understanding of homogeneous dielectric barrier discharges
Massines, F.; Gherardi, N.; Naudé, N.; Ségur, P.
2009-01-01
This paper is a state of the art of the understanding on the physics of homogeneous dielectric barrier discharges at atmospheric pressure. It is based on the analysis of present and previous work about the behavior of these discharges and the conditions to get them. Mechanisms controlling the homogeneity during gas breakdown and discharge development are successively discussed. The breakdown has to be a Townsend one, the ionization has to be slow enough to avoid a large avalanche development....
Recent advances in the understanding of homogeneous dielectric barrier discharges
Massines, F.; Gherardi, N.; Naudé, N.; Ségur, P.
2009-01-01
Abstract This paper is a state of the art of the understanding on the physics of homogeneous dielectric barrier discharges at atmospheric pressure. It is based on the analysis of present and previous work about the behavior of these discharges and the conditions to get them. Mechanisms controlling the homogeneity during gas breakdown and discharge development are successively discussed. The breakdown has to be a Townsend one, the ionization has to be slow enough to avoid a large av...
Homogenization of aligned “fuzzy fiber” composites
Chatzigeorgiou, George
2011-09-01
The aim of this work is to study composites in which carbon fibers coated with radially aligned carbon nanotubes are embedded in a matrix. The effective properties of these composites are identified using the asymptotic expansion homogenization method in two steps. Homogenization is performed in different coordinate systems, the cylindrical and the Cartesian, and a numerical example are presented. © 2011 Elsevier Ltd. All rights reserved.
Markov chain Monte Carlo test of toric homogeneous Markov chains
Takemura, Akimichi; Hara, Hisayuki
2010-01-01
Markov chain models are used in various fields, such behavioral sciences or econometrics. Although the goodness of fit of the model is usually assessed by large sample approximation, it is desirable to use conditional tests if the sample size is not large. We study Markov bases for performing conditional tests of the toric homogeneous Markov chain model, which is the envelope exponential family for the usual homogeneous Markov chain model. We give a complete description of a Markov basis for ...
Orbits in Homogeneous Oblate Spheroidal Gravitational Space-Time
Directory of Open Access Journals (Sweden)
Chifu E. N.
2009-07-01
Full Text Available The generalized Lagrangian in general relativistic homogeneous oblate spheroidal gravitational fields is constructed and used to study orbits exterior to homogenous oblate spheroids. Expressions for the conservation of energy and angular momentum for this gravitational field are obtained. The planetary equation of motion and the equation of motion of a photon in the vicinity of an oblate spheroid are derived. These equations have additional terms not found in Schwarzschild's space time.
Spray structure as generated under homogeneous flash boiling nucleation regime
International Nuclear Information System (INIS)
We show the effect of the initial pressure and temperature on the spatial distribution of droplets size and their velocity profile inside a spray cloud that is generated by a flash boiling mechanism under homogeneous nucleation regime. We used TSI's Phase Doppler Particle Analyzer (PDPA) to characterize the spray. We conclude that the homogeneous nucleation process is strongly affected by the initial liquid temperature while the initial pressure has only a minor effect. The spray shape is not affected by temperature or pressure under homogeneous nucleation regime. We noted that the only visible effect is in the spray opacity. Finally, homogeneous nucleation may be easily achieved by using a simple atomizer construction, and thus is potentially suitable for fuel injection systems in combustors and engines. - Highlights: • We study the characteristics of a spray that is generated by a flash boiling process. • In this study, the flash boiling process occurs under homogeneous nucleation regime. • We used Phase Doppler Particle Analyzer (PDPA) to characterize the spray. • The SMD has been found to be strongly affected by the initial liquid temperature. • Homogeneous nucleation may be easily achieved by using a simple atomizer unit
Stochastic Homogenization of Nonconvex Unbounded Integral Functionals with Convex Growth
Duerinckx, Mitia; Gloria, Antoine
2016-03-01
We consider the well-trodden ground of the problem of the homogenization of random integral functionals. When the integrand has standard growth conditions, the qualitative theory is well-understood. When it comes to unbounded functionals, that is, when the domain of the integrand is not the whole space and may depend on the space-variable, there is no satisfactory theory. In this contribution we develop a complete qualitative stochastic homogenization theory for nonconvex unbounded functionals with convex growth. We first prove that if the integrand is convex and has p-growth from below (with p > d, the dimension), then it admits homogenization regardless of growth conditions from above. This result, that crucially relies on the existence and sublinearity at infinity of correctors, is also new in the periodic case. In the case of nonconvex integrands, we prove that a similar homogenization result holds provided that the nonconvex integrand admits a two-sided estimate by a convex integrand (the domain of which may depend on the space variable) that itself admits homogenization. This result is of interest to the rigorous derivation of rubber elasticity from polymer physics, which involves the stochastic homogenization of such unbounded functionals.
Homogenization models for thin rigid structured surfaces and films.
Marigo, Jean-Jacques; Maurel, Agnès
2016-07-01
A homogenization method for thin microstructured surfaces and films is presented. In both cases, sound hard materials are considered, associated with Neumann boundary conditions and the wave equation in the time domain is examined. For a structured surface, a boundary condition is obtained on an equivalent flat wall, which links the acoustic velocity to its normal and tangential derivatives (of the Myers type). For a structured film, jump conditions are obtained for the acoustic pressure and the normal velocity across an equivalent interface (of the Ventcels type). This interface homogenization is based on a matched asymptotic expansion technique, and differs slightly from the classical homogenization, which is known to fail for small structuration thicknesses. In order to get insight into what causes this failure, a two-step homogenization is proposed, mixing classical homogenization and matched asymptotic expansion. Results of the two homogenizations are analyzed in light of the associated elementary problems, which correspond to problems of fluid mechanics, namely, potential flows around rigid obstacles. PMID:27475151
Medical and industrial applications
International Nuclear Information System (INIS)
The radioisotopes are produced for various applications in the nuclear medicine (diagnostic, therapy, palliation of metastatic bone pain), industry (radiography of welds,...), agriculture (radiotracers, ...) and basic research. Due to the availability of high neutron fluxes (thermal neutron flux up to 1015 n/cm2.s), the BR2 reactor is considered as a major facility through its contribution for a continuous supply of products such 99Mo (99mTc), 131I, 133Xe, 192Ir, 186Re, 153Sm, 90Y, 32P, 188W (188Re), 203Hg, 82Br, 41Ar, 125I, 177Lu, 89Sr, 60Co, 169Yb, 147Nd, ... Neutron Transmutation Doped (NTD) silicon is produced for the semiconductor industry in the SIDONIE (Silicon Doping by Neutron Irradiation Experiment) facility, which is designed to continuously rotate and traverse the silicon through the neutron flux. These combined movements produce exceptional dopant homogeneity in batches of silicon measuring 4 and 5-inches in diameter by up to 750 mm in length. The objective is to provide a reliable and qualitative supply of radioisotopes and NTD-silicon to the customers in accordance with a quality system that has been certified to the requirements of the EN ISO 9001 : 2000. This new Quality System Certificate has been obtained in November 2003 for the 'Production of radioisotopes for medical and industrial applications' and the 'Production of Neutron Transmutation Doped (NTD) Silicon' in the BR2 reactor
Medical and industrial applications
International Nuclear Information System (INIS)
The radioisotopes are produced for various applications in the nuclear medicine (diagnostic, therapy, palliation of metastatic bone pain), industry (radiography of welds ...), agriculture (radiotracers ...) and basic research. Due to the availability of high neutron fluxes (thermal neutron flux up to 1015 n/cm2.s), the BR2 reactor is considered as a major facility through its contribution for a continuous supply of products such 99Mo (99mTc), 131I, 133Xe, 192Ir, 186Re, 153Sm, 90Y, 32P, 188W (188Re), 203Hg, 82Br, 41Ar, 125I, 177Lu, 89Sr, 60Co, 169Yb, 147Nd, and others. Neutron Transmutation Doped (NTD) silicon is produced for the semiconductor industry in the SIDONIE (Silicon Doping by Neutron Irradiation Experiment) facility, which is designed to continuously rotate and traverse the silicon through the neutron flux. These combined movements produce exceptional dopant homogeneity in batches of silicon measuring 4 and 5-inches in diameter by up to 750 mm in length. To provide a reliable and qualitative supply of radioisotopes and NTD-silicon to the customers in accordance with a quality system that has been certified to the requirements of the EN ISO 9001: 2000. This new Quality System Certificate has been obtained in December 2006 for the Production of radioisotopes for medical and industrial applications and the Production of Neutron Transmutation Doped (NTD) Silicon in the BR2 reactor
... Melon Smoothie Pregnant? Your Baby's Growth The Medical Home KidsHealth > For Parents > The Medical Home Print A ... for your child. What Does the Term "Medical Home" Mean? A medical home isn't a place ...
Medical alert bracelet (image)
People with diabetes should always wear a medical alert bracelet or necklace that emergency medical workers will ... People with diabetes should always wear a medical alert bracelet or necklace that emergency medical workers will ...
Full Text Available ... Agents Antidiarrheal Agents Antidepressant Medications Newer IBS Medications Probiotics and Antibiotics Pharmacologic, or drug, therapy is best ... Agents Antidiarrheal Agents Antidepressant Medications Newer IBS Medications ... Psychological Treatments Understanding Stress Cognitive Behavioral ...
Full Text Available ... Agents Antidiarrheal Agents Antidepressant Medications Newer IBS Medications Probiotics and Antibiotics Pharmacologic, or drug, therapy is best ... Agents Antidiarrheal Agents Antidepressant Medications Newer IBS Medications Probiotics and Antibiotics Psychological Treatments Take Part in Online ...
International Nuclear Information System (INIS)
Three slide sets which can be used in lectures about radiation protection have been published by NRPB. The slide sets are based on publications in the NRPB ''At-a-Glance'' series of broadsheets, which use illustrations as the main source of information, supported by captions; the series generally avoids the jargon of radiation protection, although each leaflet is based on scientific studies. Slide Set Number 3, ''Medical Radiation'', outlines the production and use of x-rays in diagnosis, the protection of staff and patients, and the use of radioactive materials in diagnosis and radiotherapy. It summarises the use of magnetic resonance imaging. Radiation doses received during various x-ray examinations are compared with radiation doses from nature. (Author)
DEFF Research Database (Denmark)
Mønsted, Troels Sune
’. Theoretically the project departs from Computer Supported Cooperative Work and Participatory Design and is informed by Medical Informatics, Design Research and Science and Technology Studies. Methodically the project is founded on collaborative prototyping, ethnographic studies, and design interventions......IT is central for the development of modern healthcare. Until now, researchers and designers have given great attention to how IT can render clinical data accessible and support collaborative and coordinative work. By focusing on how physicians make sense of patients’ illness trajectories and by...... conceptualizing this as narrative reasoning, this PhD dissertation offers novel perspectives on design of health IT. The dissertation consists of five research articles and an extended synopsis that presents findings from three years of research within the project ‘Co-Constructing IT and Healthcare...
Naftali, Timna
2016-02-01
The cannabis plant has been known to humanity for centuries as a remedy for pain, diarrhea and inflammation. Current research is inspecting the use of cannabis for many diseases, including multiple sclerosis, epilepsy, dystonia, and chronic pain. In inflammatory conditions cannabinoids improve pain in rheumatoid arthritis and:pain and diarrhea in Crohn's disease. Despite their therapeutic potential, cannabinoids are not free of side effects including psychosis, anxiety, paranoia, dependence and abuse. Controlled clinical studies investigating the therapeutic potential of cannabis are few and small, whereas pressure for expanding cannabis use is increasing. Currently, as long as cannabis is classified as an illicit drug and until further controlled studies are performed, the use of medical cannabis should be limited to patients who failed conventional better established treatment. PMID:27215115
Toward whole-core neutron transport without spatial homogenization
International Nuclear Information System (INIS)
Full text of publication follows: A long-term goal of computational reactor physics is the deterministic analysis of power reactor core neutronics without incurring significant discretization errors in the energy, spatial or angular variables. In principle, given large enough parallel configurations with unlimited CPU time and memory, this goal could be achieved using existing three-dimensional neutron transport codes. In practice, however, solving the Boltzmann equation for neutrons over the six-dimensional phase space is made intractable by the nature of neutron cross-sections and the complexity and size of power reactor cores. Tens of thousands of energy groups would be required for faithful cross section representation. Likewise, the numerous material interfaces present in power reactor lattices require exceedingly fine spatial mesh structures; these ubiquitous interfaces preclude effective implementation of adaptive grid, mesh-less methods and related techniques that have been applied so successfully in other areas of engineering science. These challenges notwithstanding, substantial progress continues in the pursuit for more robust deterministic methods for whole-core neutronics analysis. This paper examines the progress over roughly the last decade, emphasizing the space-angle variables and the quest to eliminate errors attributable to spatial homogenization. As prolog we briefly assess 1990's methods used in light water reactor analysis and review the lessons learned from the C5G7 benchmark exercises which were originated in 1999 to appraise the ability of transport codes to perform core calculations without homogenization. We proceed by examining progress over the last decade much of which falls into three areas. These may be broadly characterized as reduced homogenization, dynamic homogenization and planar-axial synthesis. In the first, homogenization in three-dimensional calculations is reduced from the fuel assembly to the pin-cell level. In the second
Zinc chloride aqueous solution as a solvent for starch.
Lin, Meiying; Shang, Xiaoqin; Liu, Peng; Xie, Fengwei; Chen, Xiaodong; Sun, Yongyi; Wan, Junyan
2016-01-20
It is important to obtain starch-based homogeneous systems for starch modification. Regarding this, an important key point is to find cheap, low-cost and low-toxicity solvents to allow complete dissolution of starch and its easy regeneration. This study reveals that a ZnCl2 aqueous solution is a good non-derivatizing solvent for starch at 50 °C, and can completely dissolve starch granules. The possible formation of a "zinc-starch complex" might account for the dissolution; and the degradation of starch, which was caused by the H(+) inZnCl2 aqueous solution, could not contribute to full dissolution. From polarized light microscopic observation combined with the solution turbidity results, it was found that the lowest ZnCl2 concentration for full dissolution was 29.6 wt.% at 50 °C, with the dissolving time being 4h. Using Fourier-transform infrared (FTIR), solid state (13)C nuclear magnetic resonance (NMR), and X-ray diffraction (XRD), it was revealed that ZnCl2 solution had no chemical reaction with starch glucosides, but only weakened starch hydrogen bonding and converted the crystalline regions to amorphous regions. In addition, as shown by intrinsic viscosity and thermogravimetric analysis (TGA), ZnCl2 solution caused degradation of starch macromolecules, which was more serious with a higher concentration of ZnCl2 solution. PMID:26572355
Asymmetric Transfer Hydrogenation of ω -Bromo Acetophenones in Aqueous Media
Institute of Scientific and Technical Information of China (English)
Wang Fei; Liu Hui; Cui Xin; Cun Linfeng; Zhu Jin; Deng Jingen; Jiang Yaozhong
2004-01-01
Optical active ω-bromophenylethanols are useful building blocks for synthesis of various pharmaceuticals such as α 1-, β 2-, and β 3- adrenergic receptor agonists, which are always obtained though a biotransformative pathway and using boron reagent with rigorous conditions [1]. To our knowledge, the metal-catalysed transfer hydrogenation is seldom applied in this reaction. Recently we have developed a water-soluble chiral Ru-complex and applied successfully in transfer hydrogenation of ω-bromo acetophenones in aqueous media [2], which can not be performed in homogeneous system with HCOOH/NEt3 as hydrogen donor[3] .In this paper, we will report that asymmetric transfer hydrogenation of ω-bromo acetophenones was successfully performed in aqueous media by employing hydrophobic Rh-amido complex (TsDPEN-Rh) as catalyst and HCOONa as hydrogen donor. Moreover, marked increasing of activity and high enantioselectivity (up to 98%) of ω-bromo acetophenone 1a was found in the presence of different micelles or vesicles. This method was also applied successfully in preparation of the important chiral medicinal intermediates, such as the precursor of salbutamol, 2b and fermoterol, 2c with high enantioselectivity.
Low-Cost Fabrication for ZrO2-Based Electrolyte Thin-Substrate by Aqueous Gel-Casting
Institute of Scientific and Technical Information of China (English)
刘晓光; 李国军; 仝建峰; 陈大明
2004-01-01
The possibility to fabricate yttria-stabilized zirconia (YSZ) thin-substrates by aqueous gel casting of high concentrated aqueous slurries was investigated. The effects of dispersant, pH value, and solid content of slurries for gel process on stability and viscosity of slurries were optimized. YSZ thin-substrates green bodies with 100 μm thickness and 100 mm×100 mm flat plate were fabricated. Microstructure observations, density and bending measurements show that these green bodies are homogeneous and highly densified. After sintering at 1873 K×2 h, the ionic conductivity reaches 0.155 S·cm-1 at 1273 K.
Matching Medical Websites to Medical Guidelines
Dusan Rak; Vojtech Svatek
2016-01-01
The quality of medical texts provided to general public on the Internet is a serious issue nowadays. Unfortunately the only feasible way to approve the adequacy of the medical information content is human verification today. Best practices in medicine are systematically captured by medical guidelines (MGLs), which are provided by renowned medical societies. We propose a simple approach to exploiting MGL content as ’gold standard’ for the assessment of content quality in medical we...
Dzeufiet, Paul Désiré Djomeni; Mogueo, Amélie; Bilanda, Danielle Claude; Aboubakar, Bibi-Farouck Oumarou; Tédong, Léonard; Dimo, Théophile; Kamtchouing, Pierre
2014-01-01
Background The present study was designed to evaluate the effects of the aqueous extract obtained from the mixture of fresh leaf of Persea americana, stems and fresh leaf of Cymbopogon citratus, fruits of Citrus medica and honey on ethanol and sucrose induced hypertension in rats. Methods Rats were divided into eight groups of 6 rats each and daily treated for 5 weeks. The control group received distilled water (1 mL/kg) while rats of groups 2, 3 and 4 received ethanol 40 degrees (3 g/kg/day)...
Interfacial forces in aqueous media
van Oss, Carel J
2006-01-01
Thoroughly revised and reorganized, the second edition of Interfacial Forces in Aqueous Media examines the role of polar interfacial and noncovalent interactions among biological and nonbiological macromolecules as well as biopolymers, particles, surfaces, cells, and both polar and apolar polymers. The book encompasses Lifshitz-van der Waals and electrical double layer interactions, as well as Lewis acid-base interactions between colloidal entities in polar liquids such as water. New in this Edition: Four previously unpublished chapters comprising a new section on interfacial propertie
Aqueous photocatalytic oxidation of sulfamethizole.
Klauson, D; Krichevskaya, M; Borissova, M; Preis, S
2010-12-14
Aqueous photocatalytic oxidation (PCO) of a non-biodegradable sulphonamide antibiotic sulfamethizole was studied. The impacts of photocatalyst dose, initial pH, and substrate concentration in the range from 1 to 100 mg L(-1) were examined with a number of organic and inorganic by-products determined, suggesting the initial break-up of the SMZ molecule at the sulphonamide bond. The experiments were carried out under artificial near-UV and visible light, and solar radiation using Degussa P25 and less efficient visible light-sensitive C-doped titanium dioxide as photocatalysts. PMID:21275251
Approximation theory and homogenization for neutron transport processes
International Nuclear Information System (INIS)
In practical calculation of reactor systems homogenization is performed by some techniques mostly based on intuition and there is no uniquely accepted approach to this problem. In the first part of the paper an attempt is made to formulate mathematical basis of homogenization for the neutron diffusion and transport equations using recent developments in this field. The boundary value problems for both equations for non smooth H - periodic coefficients are related to appropriate variational problems stated in terms of bilinear forms. The behaviour of the solutions for H → 0 is investigated under various assumptions concerning a limit process to get the coefficients of homogenized equations. In the second part of the paper the assymptotic equivalence of the neutron diffusion to the transport equation is studied. The relation between homogenization procedures for both equations is also examined. As an example, the deriviation of the equations of homogenization in the case of hexagonal geometry typical for V.V.E.R. reactor is given. The obtained formulae for so called effective diffusion coefficient are analyzed for various types of lattices. (author)
Gartrell, Nanette
2014-01-01
Nanette Gartrell, MD, is a psychiatrist and researcher whose investigations have documented the mental health and psychological well-being of lesbian, gay, bisexual, and transgender (LGBT) people over the past four decades. Nanette is the principal investigator of an ongoing longitudinal study of lesbian families in which the children were conceived by donor insemination. Now in its 27th year, this project has been cited internationally in the debates over equality in marriage, foster care, and adoption. Previously on the faculty at Harvard Medical School and the University of California, San Francisco, Nanette is currently a Visiting Distinguished Scholar at the Williams Institute, UCLA School of Law. In 2013, Nanette received the Association of Women Psychiatrists Presidential Commendation Award for "selfless and enduring vision, leadership, wisdom, and mentorship in the fields of women's mental health, ethics, and gender research." At the age of 63, Nanette experienced a 3 ½ month period of intractable, incapacitating dizziness for which there was never a clear diagnosis. PMID:24400630
Solution properties of the acrylamide-modified cellulose polyelectrolytes in aqueous solutions.
Song, Yongbo; Zhou, Jinping; Li, Qian; Lue, Ang; Zhang, Lina
2009-07-27
A novel cellulose-based polyelectrolyte (AM-C) containing acylamino (DS=0.625) and carboxyl (DS=0.148) groups was homogeneously synthesized from cellulose with acrylamide in NaOH/urea aqueous solutions. Solution properties of AM-C in aqueous solutions were investigated by laser light scattering, rheometry, and viscometry. The results indicated that AM-C could form large aggregates spontaneously in water with or without the addition of salts by the strong hydrogen bonds and electrostatic interaction between acylamino and carboxyl groups. Steady-shear flow study showed a Newtonian behavior of the solutions in the dilute regime while a shear-thinning behavior as the concentration increases. The critical concentration (c(e)) for transition from dilute to concentrated solution was determined to be 0.7wt%. Aqueous solutions of AM-C displayed good thermo-stability, reversible liquid-like characters attributing to the chemical modification. The derivation from Cox-Merz rule at relatively low concentration was related to the co-existence of single chain and large aggregates of AM-C in dilute regime. As the polymer concentration increased, the AM-C system was transformed into a homogeneous entanglement structure, resulting in the disappearance of deviations from the Cox-Merz rule. PMID:19464674
HOMOGENIZATION, SYMMETRY, AND PERIODIZATION IN DIFFUSIVE RANDOM MEDIA
Institute of Scientific and Technical Information of China (English)
Alen Alexanderian; Muruhan Rathinam; Rouben Rostamian
2012-01-01
We present a systematic study of homogenization of diffusion in random media with emphasis on tile-based random microstructures.We give detailed examples of several such media starting from their physical descriptions,then construct the associated probability spaces and verify their ergodicity.After a discussion of material symmetries of random media,we derive criteria for the isotropy of the homogenized limits in tile-based structures.Furthermore,we study the periodization algorithm for the numerical approximation of the homogenized diffusion tensor and study the algorithm's rate of convergence.For one dimensional tile-based media,we prove a central limit result,giving a concrete rate of convergence for periodization.We also provide numerical evidence for a similar central limit behavior in the case of two dimensional tile-based structures.
A Computationally Based Approach to Homogenizing Advanced Alloys
Energy Technology Data Exchange (ETDEWEB)
Jablonski, P D; Cowen, C J
2011-02-27
We have developed a computationally based approach to optimizing the homogenization heat treatment of complex alloys. The Scheil module within the Thermo-Calc software is used to predict the as-cast segregation present within alloys, and DICTRA (Diffusion Controlled TRAnsformations) is used to model the homogenization kinetics as a function of time, temperature and microstructural scale. We will discuss this approach as it is applied to both Ni based superalloys as well as the more complex (computationally) case of alloys that solidify with more than one matrix phase as a result of segregation. Such is the case typically observed in martensitic steels. With these alloys it is doubly important to homogenize them correctly, especially at the laboratory scale, since they are austenitic at high temperature and thus constituent elements will diffuse slowly. The computationally designed heat treatment and the subsequent verification real castings are presented.
Heterogenization of Homogeneous Catalysts: the Effect of the Support
Energy Technology Data Exchange (ETDEWEB)
Earl, W.L.; Ott, K.C.; Hall, K.A.; de Rege, F.M.; Morita, D.K.; Tumas, W.; Brown, G.H.; Broene, R.D.
1999-06-29
We have studied the influence of placing a soluble, homogeneous catalyst onto a solid support. We determined that such a 'heterogenized' homogeneous catalyst can have improved activity and selectivity for the asymmetric hydrogenation of enamides to amino acid derivatives. The route of heterogenization of RhDuPhos(COD){sup +} cations occurs via electrostatic interactions with anions that are capable of strong hydrogen bonding to silica surfaces. This is a novel approach to supported catalysis. Supported RhDuPhos(COD){sup +} is a recyclable, non-leaching catalyst in non-polar media. This is one of the few heterogenized catalysts that exhibits improved catalytic performance as compared to its homogeneous analog.
Damping the neutrino flavor pendulum by breaking homogeneity
Mangano, Gianpiero; Saviano, Ninetta
2014-01-01
The most general case of self-induced neutrino flavor evolution is described by a set of kinetic equations for a dense neutrino gas evolving both in space and time. Solutions of these equations have been typically worked out assuming that either the time (in the core-collapse supernova environment) or space (in the early universe) homogeneity in the initial conditions is preserved through the evolution. In these cases one can gauge away the homogeneous variable and reduce the dimensionality of the problem. In this paper we investigate if small deviations from an initial postulated homogeneity can be amplified by the interacting neutrino gas, leading to a new flavor instability. To this end, we consider a simple two flavor isotropic neutrino gas evolving in time, and initially composed by only $\
Homogeneous versus heterogeneous shielding modeling of spent-fuel casks
International Nuclear Information System (INIS)
The design of spent-fuel casks for storage and transport requires modeling the cask for criticality, shielding, thermal, and structural analyses. While some parts of the cask are homogeneous, other regions are heterogeneous with different materials intermixed. For simplicity, some of the heterogeneous regions may be modeled as homogeneous. This paper evaluates the effect of homogenizing some regions of a cask on calculating radiation dose rates outside the cask. The dose rate calculations were performed with the one-dimensional discrete ordinates shielding XSDRNPM code coupled with the XSDOSE code and with the three-dimensional QAD-CGGP code. Dose rates were calculated radially at the midplane of the cask at two locations, cask surface and 2.3 m from the radial surface. The last location corresponds to a point 2 m from the lateral sides of a transport railroad car
Permutation-based Homogeneous Block Content Authentication for Watermarking
Directory of Open Access Journals (Sweden)
S.Maruthuperumal
2013-02-01
Full Text Available In modern days, digital watermarking has become an admired technique for hitting data in digital images to help guard against copyright infringement. The proposed Permutation-based Homogeneous Block Content authentication (PHBC methods develop a secure and excellence strong watermarking algorithm that combines the reward of permutation-based Homogeneous block (PHB with that of significant and insignificant bit values with X0R encryption function using Max coefficient of least coordinate value for embedding the watermark. In the projected system uses the relationship between the permutation blocks to embed many data into Homogeneous blocks without causing solemn distortion to the watermarked image. The experimental results show that the projected system is very efficient in achieving perceptual invisibility with an increase in the Peak Signal to Noise Ratio (PSNR. Moreover, the projected system is robust to a variety of signal processing operations, such as image Cropping, Rotation, Resizing, Adding noise, Filtering , Blurring and Motion blurring.
Homogenized behaviour of the steam generator perforated plates
International Nuclear Information System (INIS)
To determine the overall behaviour of structures such as multiperforated plates, that are found in the industrial components (for instance in the nuclear plant steam generators), we propose to apply the theory of the heterogeneous thermoelastic plates. First we begin by the formulation of the model, lying on an asymptotic expansion. Then we describe the application to the tube sheet and support plates case, for 900 MW and 1300 MW steam generators. Numerical values of the homogenized behaviour are provided (thermal conductivity and thermoelastic coefficients). These values are compared with those available in the literature. Some comments on the mechanical fields distribution are added, for instance: hole ovalization, stress concentrations... This study completes earlier EDF works on the thermal and mechanical homogenization of the tube sheets, which are realized before the theoretical formulation of the homogenization for plates and shells structures. (author). 16 figs., 21 tabs., 14 refs
Recycling and Reuse of Ionic Liquid in Homogeneous Cellulose Acetylation
Institute of Scientific and Technical Information of China (English)
HUANG Kelin; WU Rui; CAO Yan; LI Huiquan; WANG Jinshu
2013-01-01
Molecular distillation was used to recover ionic liquid (IL) 1-allyl-3-methylimidazolium chloride (AmimC1) in homogeneous cellulose acetylation.The five factors that affect the separation efficiency of molecular distillation,namely,feed flow rate,distillation temperature,feed temperature,wiper rotating speed,and distillation pressure,are discussed.The optimal recovery condition was determined via orthogonal experiments using an OA9(34) design.The IL was recycled and reused 5 times in the homogeneous cellulose acetylation system under optimal conditions.The purity of recycled IL the 5th time reached 99.56％.FT-IR (Fourier transform infrared spectroscopy) and 1H NMR (nuclear magnetic resonance) spectroscopy showed that the structure of the recovered IL is not changed.This work proves that AmirnCl has excellent reusability,and that molecular distillation is an effective method for recovering IL in homogeneous cellulose acetylation.
MacDiarmid, A.; Kaner, R.; Mammone, R.; Heeger, A.
1983-01-01
Polyacetylene can be doped either chemically or electrochemically in aqueous solution to the metallic regime. The characteristics of selected rechargeable batteries employing (CH)x, electrodes in non-aqueous electrolytes are described.
Encapsulation of volatiles by homogenized partially-cross linked alginates.
Inguva, Pavan K; Ooi, Shing Ming; Desai, Parind M; Heng, Paul W S
2015-12-30
Cross-linked calcium alginate gels are too viscous to be efficaciously incorporated into spray dried formulations. Thus, viscosity reduction is essential to ensure the processability of calcium alginate gels to be sprayed. Viscosity reduction by high pressure homogenization can open new formulation possibilities. Presently, testing of microcapsule integrity is also limited because either single particle tests neglect collective particle behaviours in bulk or bulk testing methods are often associated with single compressions which may not fully characterize individual particle strengths. The aim of this study was sub-divided into three objectives. First objective was to evaluate the impact of high pressure homogenization on gel viscosity. Second objective was to explore the use of the homogenized gels with modified starch for microencapsulation by spray drying. The final objective was to develop a stamping system as microcapsule strength tester that can assess microcapsules in bulk and evaluate the impact of multiple compressions. Collectively, this study would lead towards developing a pressure-activated patch of microcapsules with encapsulated volatiles and the method to assess the patch efficacy. The alginate gels largely experienced an exponential decay in viscosity when homogenized. Furthermore, the homogenized gels were successfully incorporated in spray drying formulations for microencapsulation. The custom-designed microcapsule strength tester was successfully used and shown to possess the required sensitivity to discern batches of microcapsules containing volatiles to have different release profiles. Addition of homogenized gels strengthened the microcapsules only at high wall to core ratios with low mass-load alginate gels. High mass-load gels weaken the microcapsules, exhibiting a higher release at low stamping pressures and wrinkling on the microcapsules surface. PMID:26581772
Absolute homogeneity test of Kelantan catchment precipitation series
Ros, Faizah Che; Tosaka, Hiroyuki; Sasaki, Kenji; Sidek, Lariyah Mohd; Basri, Hidayah
2015-05-01
Along the Kelantan River in north east of Malaysia Peninsular, there are several areas often damaged by flood during north-east monsoon season every year. It is vital to predict the expected behavior of precipitation and river runoff for reducing flood damages of the area under rapid urbanization and future planning. Nevertheless, the accuracy and reliability of any hydrological and climate studies vary based on the quality of the data used. The factors causing variations on these data are the method of gauging and data collection, stations environment, station relocation and the reliability of the measurement tool affect the homogenous precipitation records. Hence in this study, homogeneity of long precipitation data series is checked via the absolute homogeneity test consisting of four methods namely Pettitt test, standard normal homogeneity test (SNHT), Buishand range test and Von Neumann ratio test. For homogeneity test, the annual rainfall amount from the daily precipitation records at stations located in Kelantan operated by Department of Irrigation and Drainage Malaysia were considered in this study. The missing values were completed using the correlation and regression and inverse distance method. The data network consists of 103 precipitation gauging stations where 31 points are inactive, 6 gauging stations had missing precipitation values more than five years in a row and 16 stations have records less than twenty years. So total of 50 stations gauging stations were evaluated in this analysis. With the application of the mentioned methods and further graphical analysis, inhomogeneity was detected at 4 stations and 46 stations are found to be homogeneous.
Furusawa, Naoto
2004-05-01
A simple and hazardous chemical-free method for the high-performance liquid chromatographic determination of oxytetracycline (OTC) residues in milk and eggs has been developed. Sample preparation consists in homogenization with an aqueous solution by means of a handheld ultrasonic homogenizer followed by centrifugal ultrafiltration. HPLC is performed with an isocratic aqueous mobile phase and a photodiode array detector. Average recoveries of OTC (0.05, 0.1, and 0.2 microg mL(-1) for milk; 0.1, 0.2, and 0.4 microg mL(-1) for eggs) were > or =84% with relative standard deviations of solvents or hazardous reagents were used. PMID:15335039
Moretti, Michael
1991-08-01
Solid state lasers are the real highlight of my talk today, and were really the star of the year. In every application area I can think of, people have tried with some success to introduce corturiercial solid state products. I'll go into more detail, but aside from solid state, a very significant event happened in Deceniber when one of the laser angioplasty companies (Advanced Interventional Systens) received FDA clearance to begin marketing the excimer for coronary applications (Figure 1) . This is the first time to my knowledge that an excimer has ever been cleared for a medical application in the United States. It's an event that we didn't really expect to happen so soon. It's extremely significant and we'll see where it goes from here. The system needs to be road-tested a bit but to get past the FDA is the major obstacle. Looking back to solid state laser the importance of solid state lasers is as researchers become more involved with the excimer and conduct more clinical studies in ophthalmology, they realize that it's not going to be a panacea for all refractive surgery or other ophthalmolic applications. In many cases it looks like the solid state laser may be the laser of choice in certain types of surgery; most notably perhaps in refractive surgery. We've all read about the success of the excimer at least in capturing the press's attention for corneal sculpting and vision correction. Well, it could be that actually the next generation will be a solid state laser, so let's keep an open mind here.
Homogeneous neutron absorbers as technological components of nuclear fuel regeneration processes
International Nuclear Information System (INIS)
A subcritical state of a system with fissionable materials whose quantity, concentration, and volume exceed the criticality parameters, is maintained by using not only insoluble (heterogeneous) but also soluble (homogeneous) neutron absorbers, such as water-soluble compounds of elements with a large neutron capture cross section, namely, gadolinium, cadmium, hafnium, and boron (boric acid, tetrafluoboric acid). A comprehensive solution for the nuclear safety of heterogeneous (two-phase) systems can be found by using boron-containing extractants, solvents, and sorbents. In this article the results of tests of various homogeneous neutron absorbers and an assessment of their suitability are reported. The possibility of their repeated use (recycling) is also explored. In a rough approximation (without allowance for the variation of the moderation ratio H/ME) the maintenance of the conditions for subcriticality of a system with fissionable materials (K∞ ≤ 1) is determined by the balance of the macroscopic thermal-neutron absorption cross section to the macroscopic cross section for the fission of actinide nuclei. The absorbers are most effective in aqueous solutions since in this case all of their nuclei participate in the process. When absorbers are used fissionable materials must be removed from them at the end of the technological cycle; the possibility of their accidentally escaping from the system with fissionable materials (stratification, sedimentation) checks must be made to make sure that the concentration remains constant. Assuming that the use of absorbers is most effective in the dissolution of nuclear fuel, in evaporators and containers for intermediate storage, and when scrubbing fissionable materials from large-volume equipment, the prospects of developing extractants, ion-exchange resins, and other reagents with an absorber have been found to be promising
International Nuclear Information System (INIS)
Steady state and time-resolved fluorescence properties of porphyrin appended 1,3,4-oxadiazoles and thiazoles were described in homogeneous medium as well as in presence of cationic surfactant cetyltrimethylammonium bromide (CTAB). The electron withdrawing substituent on the porphyrin moiety in both the cases make a donor–spacer–acceptor type of intramolecular photoinduced electron transfer (PET) system resulting substantial quenching in porphyrin fluorescence due to partial energy migration towards the acceptor in the excited state. The increase in fluorescence yield as well as appreciable difference in fluorescence decay behavior in aqueous buffer solution of pH 4.2 from that in chloroform solution is believed due to partial protonation of the porphyrin ring. All the investigated systems show preferential binding into the interfacial region of the micellar sub-domain with varying degree of penetration depending on the nature of the substituent. Almost 2–4 fold increase in fluorescence yield for the probes is explained on the basis of restricted flexibility and corresponding decrease in total nonradiative rate inside the micellar interface layer. - Highlights: ► Synthesis and detail fluorescence studies of a series of porphyrin appended 1,3,4-oxadiazoles and thiazoles. ► Comparison of homogeneous solvent study with that in CTAB. ► Substantial porphyrin fluorescence quenching in donor–spacer–acceptor type system. ► Preferential binding of the substituted porphyrins in micellar sub-domain. ► Appreciable increase in fluorescence yield in micellar interface layer is due to decrease in total nonradiative rate.
Ma, Liang; Tu, Chunlai; Le, Phuong; Chitoor, Shweta; Lim, Sung Jun; Zahid, Mohammad U; Teng, Kai Wen; Ge, Pinghua; Selvin, Paul R; Smith, Andrew M
2016-03-16
Quantum dots are fluorescent nanoparticles used to detect and image proteins and nucleic acids. Compared with organic dyes and fluorescent proteins, these nanocrystals have enhanced brightness, photostability, and wavelength tunability, but their larger size limits their use. Recently, multidentate polymer coatings have yielded stable quantum dots with small hydrodynamic dimensions (≤10 nm) due to high-affinity, compact wrapping around the nanocrystal. However, this coating technology has not been widely adopted because the resulting particles are frequently heterogeneous and clustered, and conjugation to biological molecules is difficult to control. In this article we develop new polymeric ligands and optimize coating and bioconjugation methodologies for core/shell CdSe/CdxZn1-xS quantum dots to generate homogeneous and compact products. We demonstrate that "ligand stripping" to rapidly displace nonpolar ligands with hydroxide ions allows homogeneous assembly with multidentate polymers at high temperature. The resulting aqueous nanocrystals are 7-12 nm in hydrodynamic diameter, have quantum yields similar to those in organic solvents, and strongly resist nonspecific interactions due to short oligoethylene glycol surfaces. Compared with a host of other methods, this technique is superior for eliminating small aggregates identified through chromatographic and single-molecule analysis. We also demonstrate high-efficiency bioconjugation through azide-alkyne click chemistry and self-assembly with hexa-histidine-tagged proteins that eliminate the need for product purification. The conjugates retain specificity of the attached biomolecules and are exceptional probes for immunofluorescence and single-molecule dynamic imaging. These results are expected to enable broad utilization of compact, biofunctional quantum dots for studying crowded macromolecular environments such as the neuronal synapse and cellular cytoplasm. PMID:26863113
Computational Homogenization of Fresh Concrete Flow Around Reinforcing Bars
Kolařík, Filip; Zeman, Jan
2016-01-01
Motivated by casting of fresh concrete in reinforced concrete structures, we introduce a numerical model of a steady-state non-Newtonian fluid flow through a porous domain. Our approach combines homogenization techniques to represent the reinforced domain by the Darcy law with an interface coupling of the Stokes and Darcy flows through the Beavers-Joseph-Saffman conditions. The ensuing two-scale problem is solved by the Finite Element Method with consistent linearization and the results obtained from the homogenization approach are verified against fully resolved direct numerical simulations.
Studying homogeneity region of CdAs2
International Nuclear Information System (INIS)
By means of thermal, X-ray phase, microstructural analyses and the measurements of microhardness, electric conductivity, the Hall constant and thermoelectric power the Cd-As system has been studied in the 60-70 at.% range of As concentrations (where the CdAs2 compound exists). CdAs2 has been found to have a duel homogeneity region, whose boundaries have been determined. Possible solid solutions for binary compounds with a duel homogeneity region have been analyzed and CdAs2 has been chosen
Automated homogeneous oxalate precipitation of Pu(III)
International Nuclear Information System (INIS)
Homogeneous oxalate precipitation using diethyl oxalate was compared to precipitating Pu(III) oxalate with solid oxalic acid. The diethyl oxalate technique at 75 degree C is better because it gives 50% less plutonium in the filtrate with a reasonable filtering time. Also, the procedure for the homogeneous precipitation is easier to automate because the liquid diethyl oxalate is simpler to introduce into the precipitator than solid oxalic acid. It also provides flexibility because the hydrolysis rate and therefore the precipitation rate can be controlled by varying the temperature. 5 refs., 3 figs., 3 tabs
Homogenizer of cement mix with liquid and bulk radioactive wastes
International Nuclear Information System (INIS)
The lid of the homogenizer vessel with a stirrer and with bulk and liquid inlets is firmly attached to the homogenizer frame. The mixing vessel is screwed onto the lid and is connected to the frame with two moving arms. This allows to separate the mixing vessel from the lid without having to disconnect the supplies of bulk and liquid materials. The vessel is attached to swing arms pivoted in joints, which allows servicing, turning and tipping the vessel, thereby facilitating its emptying. This facilitates cleaning and reduces the maintenance time, thus increasing the safety of personnel. (J.B.). 2 figs
Load Balancing in a Networked Environment through Homogenization
Hossain, M Shahriar; Deb, Debzani; Khan, Kazi Muhammad Najmul Hasan; Joarder, Md Mahbubul Alam
2011-01-01
Distributed processing across a networked environment suffers from unpredictable behavior of speedup due to heterogeneous nature of the hardware and software in the remote machines. It is challenging to get a better performance from a distributed system by distributing task in an intelligent manner such that the heterogeneous nature of the system do not have any effect on the speedup ratio. This paper introduces homogenization, a technique that distributes and balances the workload in such a manner that the user gets the highest speedup possible from a distributed environment. Along with providing better performance, homogenization is totally transparent to the user and requires no interaction with the system.
Analysis of stability of a homogeneous state of anisotropic plasma
International Nuclear Information System (INIS)
Small-amplitude waves in collisionless magnetized plasma are considered in the framework of one-fluid anisotropic magnetohydrodynamics with allowance for the anisotropy of the pressure and thermal flux. Stability of a homogeneous plasma state is analyzed using an eighth-order dispersion relation. Restrictions on the parameters of the homogeneous state at which the dispersion relation has no complex roots at any value of the angle between the wave vector and the unperturbed magnetic field are obtained. The applied method also makes it possible to determine the types of unstable waves
Analysis of stability of a homogeneous state of anisotropic plasma
Energy Technology Data Exchange (ETDEWEB)
Zakharov, V. Yu., E-mail: vladiyuz@mail.ru; Chernova, T. G., E-mail: chernova-tg@yandex.ru; Stepanov, S. E., E-mail: stepanov@bmstu-kaluga.ru [Bauman Moscow State Technical University, Kaluga Branch (Russian Federation)
2015-04-15
Small-amplitude waves in collisionless magnetized plasma are considered in the framework of one-fluid anisotropic magnetohydrodynamics with allowance for the anisotropy of the pressure and thermal flux. Stability of a homogeneous plasma state is analyzed using an eighth-order dispersion relation. Restrictions on the parameters of the homogeneous state at which the dispersion relation has no complex roots at any value of the angle between the wave vector and the unperturbed magnetic field are obtained. The applied method also makes it possible to determine the types of unstable waves.
Hydrogen Production by Homogeneous Catalysis: Alcohol Acceptorless Dehydrogenation
DEFF Research Database (Denmark)
Nielsen, Martin
2015-01-01
for the energy sector is the application of a hydrogen economy, which transform the chemical energy in water and/or biomass into hydrogen. Considered as an energy carrier, hydrogen is then transported to the site of use where fuel cells convert its chemical energy into electricity.Here, we review the progress...... in hydrogen production from biomass using homogeneous catalysis. Homogeneous catalysis has the advance of generally performing transformations at much milder conditions than traditional heterogeneous catalysis, and hence it constitutes a promising tool for future applications for a sustainable energy sector...
Solvable models of strings in homogeneous plane wave backgrounds
Blau, Matthias; O'Loughlin, Martin; Papadopoulos, George; Tseytlin, Arkady A.
2003-01-01
We solve closed string theory in all regular homogeneous plane-wave backgrounds with homogeneous NS three-form field strength and a dilaton. The parameters of the model are constant symmetric and anti-symmetric matrices k_{ij} and f_{ij} associated with the metric, and a constant anti-symmetric matrix h_{ij} associated with the NS field strength. In the light-cone gauge the rotation parameters f_{ij} have a natural interpretation as a constant magnetic field. This is a generalisation of the s...
Homogeneous illusion device exhibiting transformed and shifted scattering effect
Mei, Jin-Shuo; Wu, Qun; Zhang, Kuang; He, Xun-Jun; Wang, Yue
2016-06-01
Based on the theory of transformation optics, a type of homogeneous illusion device exhibiting transformed and shifted scattering effect is proposed in this paper. The constitutive parameters of the proposed device are derived, and full-wave simulations are performed to validate the electromagnetic properties of transformed and shifted scattering effect. The simulation results show that the proposed device not only can visually shift the image of target in two dimensions, but also can visually transform the shape of target. It is expected that such homogeneous illusion device could possess potential applications in military camouflage and other field of electromagnetic engineering.
Avci, Nursen; Smet, Philippe; Lauwaert, Johan; Vrielinck, Henk; Poelman, Dirk
2011-01-01
Clear aluminium oxide sols without precipitation were synthesized via a non-aqueous sol-gel technique using three different alcohols (ethanol, isopropanol and n-butyl alcohol) as solvent, aluminium sec-butoxide as a precursor and acetyl acetone as a chelating agent. Although all sols could be successfully used to prepare thin films, the most stable one was prepared with n-butyl alcohol. Highly transparent, homogenous and amorphous aluminium oxide thin films were obtained on Si substrates afte...
Sheng, Ke; Fang, Weidong; Zhu, Yingcheng; Shuai, Guangying; Zou, Dezhi; Su, Meilan; Han, Yu; Cheng, Oumei
2016-01-01
HIGHLIGHTS Eighteen EOPD, 21 LOPD and 37 age-matched normal control subjects participated in the resting state fMRI scans.Age at onset of PD modulates the distribution of cerebral regional homogeneity during resting state.Disproportionate putamen alterations are more prominent in PD patients with a younger age of onset. Objective: Early-onset Parkinson's disease (EOPD) is distinct from late-onset PD (LOPD) as it relates to the clinical profile and response to medication. The objective of current paper is to investigate whether characteristics of spontaneous brain activity in the resting state are associated with the age of disease onset. Methods: We assessed the correlation between neural activity and age-at-onset in a sample of 39 PD patients (18 EOPD and 21 LOPD) and 37 age-matched normal control subjects. Regional homogeneity (ReHo) approaches were employed using ANOVA with two factors: PD and age. Results: In the comparisons between LOPD and EOPD, EOPD revealed lower ReHo values in the right putamen and higher ReHo values in the left superior frontal gyrus. Compared with age-matched control subjects, EOPD exhibited lower ReHo values in the right putamen and higher ReHo values in the left inferior temporal gyrus; However, LOPD showed lower ReHo values in the right putamen and left insula. The ReHo values were negatively correlated with the UPDRS total scores in the right putamen in LOPD, but a correlation between the ReHo value and UPDRS score was not detected in EOPD. Conclusions: Our findings support the notion that age at onset is associated with the distribution of cerebral regional homogeneity in the resting state and suggest that disproportionate putamen alterations are more prominent in patients with a younger age of onset. PMID:27462265
Impact of medical informatics on medical education.
Hou, S M
1999-11-01
In recent years, medical informatics has become a well-recognized branch of medicine. It is a multidisciplinary science that combines information technology and various specialties of medicine. The impact of medical informatics on medical education is advancing along with the rapid developments in computer science. Departments of medical informatics or similar divisions have appeared in schools of medicine in Taiwan in the past 5 years. At National Taiwan University College of Medicine, we offer curricula in basic computer concepts, network concepts, operating systems, word processing, database and data processing, computer media resources, multimedia computer statistics, intelligent health information systems, medical diagnostic support systems, and electronic medical record systems. Distance learning has also been favorably accepted on this campus. Recently, we proposed the concept of a virtual medical campus, which will break the physical barriers of time and space. We expect this revolution to influence every aspect of medicine, especially medical education. PMID:10705693
DEHYDRATION CONDENSATION IN AQUEOUS SOLUTION
Energy Technology Data Exchange (ETDEWEB)
Steinman, Gary; Kenyon, Dean H.; Calvin, Melvin
1965-04-01
EARLIER investigations have demonstrated that di-cyandiamide (DCDA), the dimer of cyanamide, can successfully promote the dehydration condensation of: (1) glucose and orthophosphate to give glucose-6-phosphate; (2) adenosine and orthophosphate to give adenosine-5'-monophosphate; (3) orthophosphate to give pyrophosphate; (4) alanine to give alanylalanine and alanylalanylalanine. These reactions were carried out in dilute aqueous solutions in the dark. (It was also demonstrated that the combination of ultra-violet light and dicyandiamide could promote the synthesis of dipeptides. This observation has since been confirmed by other investigators.) These experiments were designed to demonstrate one possible means by which such compounds could have been formed on the prebiotic Earth, thus providing materials needed for the origin of living systems. Dicyandiamide itself could have been, present on the primitive Earth as was demonstrated with the ultra-violet irradiation of cyanide solution.
Aqueous supercapacitors on conductive cotton
Pasta, Mauro
2010-06-01
Wearable electronics offer the combined advantages of both electronics and fabrics. In this article, we report the fabrication of wearable supercapacitors using cotton fabric as an essential component. Carbon nanotubes are conformally coated onto the cotton fibers, leading to a highly electrically conductive interconnecting network. The porous carbon nanotube coating functions as both active material and current collector in the supercapacitor. Aqueous lithium sulfate is used as the electrolyte in the devices, because it presents no safety concerns for human use. The supercapacitor shows high specific capacitance (~70-80 F·g-1 at 0.1 A·g-1) and cycling stability (negligible decay after 35,000 cycles). The extremely simple design and fabrication process make it applicable for providing power in practical electronic devices. © 2010 Tsinghua University Press and Springer-Verlag Berlin Heidelberg.
Soft matter at aqueous interfaces
Liu, Yi
2016-01-01
This book covers the science of interfaces between an aqueous phase and a solid, another liquid or a gaseous phase, starting from the basic physical chemistry all the way to state-of-the-art research developments. Both experimental and theoretical methods are treated thanks to the contributions of a distinguished list of authors who are all active researchers in their respective fields. The properties of these interfaces are crucial for a wide variety of processes, products and biological systems and functions, such as the formulation of personal care and food products, paints and coatings, microfluidic and lab-on-a-chip applications, cell membranes, and lung surfactants. Accordingly, research and expertise on the subject are spread over a broad range of academic disciplines and industrial laboratories. This book brings together knowledge from these different places with the aim of fostering education, collaborations and research progress.
Detergency of stainless steel surface soiled with human brain homogenate: an XPS study
Energy Technology Data Exchange (ETDEWEB)
Richard, M. [Ecole Centrale de Lyon, UMR 5513 LTDS, 69 134 Ecully (France) and Laboratoires ANIOS, 59 260 Lille-Hellemmes (France)]. E-mail: marlene.richard@ec-lyon.fr; Le Mogne, Th. [Ecole Centrale de Lyon, UMR 5513 LTDS, 69 134 Ecully (France); Perret-Liaudet, A. [Hopital Neurologique de Lyon et INSERM U512, 69 394 Lyon (France); Rauwel, G. [Laboratoires ANIOS, 59 260 Lille-Hellemmes (France); Criquelion, J. [Laboratoires ANIOS, 59 260 Lille-Hellemmes (France); De Barros, M.I. [Ecole Centrale de Lyon, UMR 5513 LTDS, 69 134 Ecully (France); Cetre, J.C. [Unite d' Hygiene et d' Epidemiologie, Hopital de la Croix Rousse, 69 317 Lyon (France); Martin, J.M. [Ecole Centrale de Lyon, UMR 5513 LTDS, 69 134 Ecully (France)
2005-02-15
In the detergency field of re-usable medical devices, a special attention is focused on the non conventional transmissible agent called prions which is a proteinaceous infectious agent. Few cleaning procedures are effective against prions and few techniques are available to study cleaning effectiveness with respect to proteins in general. In our study, X-ray photoelectron spectroscopy (XPS) has been used to evaluate the effectiveness of detergent formulations to remove proteins from stainless steel surface soiled with a brain homogenate (BH) from human origin. Our results showed that XPS is a reliable surface analysis technique to study chemical species remaining on surface and substrate properties after cleaning procedures. A semi-quantitative evaluation of the detergency effectiveness could also be performed.
Detergency of stainless steel surface soiled with human brain homogenate: an XPS study
International Nuclear Information System (INIS)
In the detergency field of re-usable medical devices, a special attention is focused on the non conventional transmissible agent called prions which is a proteinaceous infectious agent. Few cleaning procedures are effective against prions and few techniques are available to study cleaning effectiveness with respect to proteins in general. In our study, X-ray photoelectron spectroscopy (XPS) has been used to evaluate the effectiveness of detergent formulations to remove proteins from stainless steel surface soiled with a brain homogenate (BH) from human origin. Our results showed that XPS is a reliable surface analysis technique to study chemical species remaining on surface and substrate properties after cleaning procedures. A semi-quantitative evaluation of the detergency effectiveness could also be performed
International Nuclear Information System (INIS)
Measurement of lead equivalent thickness was conducted on set of rubber gloves that were formulated for used in medical applications. A narrow beam of scattered radiation was employed for the transmission measurement. Radcal corporation ionisation chamber of 6 cc was used to measure the incident and transmitted x-ray beam. The lead equivalent thickness for the gloves were determined at 50 kV, 80 kV, 100 kV and 125 kV. The homogeneity of the gloves and its efficiency for dose reduction were also measured. A knowledge on photon mass attenuation coefficient of lead in incident x-ray energy is essential in the measurement. The measurements were carried out based on the procedure as outlined by IEC 1331-1 with a minor modification to suit the facilities in MINT. (Author)
Nickel N-heterocyclic carbene complexes in homogeneous catalysis
Berding, Joris
2009-01-01
Described in this thesis are the investigations into the chemistry of N-heterocyclic carbene (NHC) ligands and transition-metal complexes thereof. Specifically, a variety of N-heterocyclic carbene complexes of nickel were prepared, characterized and used as catalysts in three types of homogeneous ca
Microreactor Platforms for HomogeneousHydrogenations and Photocatalytic Reactions
Czech Academy of Sciences Publication Activity Database
Pavlorková, Jana; Křišťál, Jiří; Drhová, Magdalena; Hejda, S.; Klusoň, Petr
Prague: KANAG -TISK, 2014 - (Krýsa, J.; Klusoň, P.), s. 43-45 ISBN 978-80-7080-886-3. [Czech-Austrian Workshop: New Trends in Photo and Electro Catalysis /6./. Hnanice (CZ), 02.12.2013-04.12.2013] Institutional support: RVO:67985858 Keywords : microreactors * homogeneous catalysis * photocatalysis Subject RIV: CI - Industrial Chemistry, Chemical Engineering
Homogeneous Catalytic Transfer Hydrogenation in Microfluidic Flow System
Czech Academy of Sciences Publication Activity Database
Pavlorková, Jana; Křišťál, Jiří; Klusoň, Petr
Budapest: Budapest University of Technology and Economics, 2014, s. 207-208. ISBN 978-963-05-9518-6. [International Conference on Microreactor Technology IMRET /13./. Budapest (HU), 23.06.2014-25.06.2014] Institutional support: RVO:67985858 Keywords : homogeneous catalysis * transfer hydrogenation * micro structured reactor systems Subject RIV: CI - Industrial Chemistry, Chemical Engineering
Homogeneous Nucleation Rate Measurements in Supersaturated Water Vapor II
Czech Academy of Sciences Publication Activity Database
Brus, David; Ždímal, Vladimír; Uchtmann, H.
2009-01-01
Roč. 131, č. 7 (2009), , , , , 074507-1--9. ISSN 0021-9606 R&D Projects: GA AV ČR IAA200760905 Institutional research plan: CEZ:AV0Z40720504 Keywords : homogeneous nucleation * water * thermal diffusion cloud chamber Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.093, year: 2009
Homogenization of periodic elastic composites and locally resonant sonic materials
Nemat-Nasser, Sia; Willis, John R.; Srivastava, Ankit; Amirkhizi, Alireza V.
2011-03-01
A method for homogenization of an elastic composite with periodic microstructure is presented, focusing on the Floquet-type elastic waves. The resulting homogenized frequency-dependent elasticity and mass density then automatically satisfy the overall conservation laws and by necessity produce the exact dispersion relations. It is also shown that the dispersion relations and the associated field quantities can be accurately calculated using a mixed variational approach, based on the microstructure of the associated unit cell. The method is used to calculate the dynamic effective parameters for a layered composite by using both the exact solution and the results of the mixed variational formulation. The exact and approximate results are shown to be in close agreement, which makes it possible to use the approximate method for the proposed type of homogenization in cases where an exact solution does not exist. The homogenized frequency-dependent effective parameters give rise to the concept of dynamic Ashby charts that can be used to illustrate the effect of the microstructural architecture on the dynamic properties of a composite. In particular, the charts vividly display how this effective stiffness and density vary with frequency and may attain negative values within certain frequency ranges which can be changed as desired using the microarchitecture while keeping the volume fraction of the unit cell’s constituents constant.
Homogenization of Stokes and Navier-Stokes equations
International Nuclear Information System (INIS)
This thesis is devoted to homogenization of Stokes and Navier-Stokes equations with a Dirichlet boundary condition in a domain containing many tiny obstacles. Tipycally those obstacles are distributed at the modes of a periodic lattice with same small period in each axe's direction, and their size is always asymptotically smaller than the lattice's step. With the help of the energy method, and thanks to a suitable pressure's extension, we prove the convergence of the homogenization process when the lattice's step tends to zero (and thus the number of obstacles tends to infinity). For a so-called critical size of the obstacles, the homogenized problem turns out to be a Brinkman's law (i.e. Stokes or Navier-Stokes equation plus a linear zero-order term for the velocity in the momentum equation). For obstacles which have a size smaller than the critical one, the limit problem reduces to the initial Stokes or Navier-Stokes equations, while for larger sizes the homogenized problem a Darcy's law. Furthermore, those results have been extended to the case of obstacles included in a hyperplane, and we establish a simple model of fluid flows through grids, which is based on a special form of Brinkman's law
Kinetic theory of plasma waves: Part II homogeneous plasma
Westerhof, E.
2000-01-01
The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves are discussed in the limit of the cold
KINETIC THEORY OF PLASMA WAVES: Part II: Homogeneous Plasma
Westerhof, E.
2010-01-01
The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves are discussed in the limit of the cold
Kinetic theory of plasma waves - Part II: Homogeneous plasma
Westerhof, E.
2008-01-01
The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves axe discussed in the limit of the cold
On superspinor structure of homogeneous superspace of orthosymplectic groups
International Nuclear Information System (INIS)
Superspinor structure of homogeneous superspaces of orthosymplectic groups are considered. It is shown how the properties of orthosymplectic group superspaces of OSp(N, 2K) group playing an important role in the supersymmetry theory can be described using superspinors. An example confirming a possibility of the relation between . canonical ratios of Butten bracket and conventional methods of quantization is considered
Bose-Einstein condensate in non-homogeneous gravitational field
Kulikov, Igor
2002-01-01
Ground state properties of trapped Bose condensate with repulsive interaction in non-homogeneous gravitational field are studied. Spatial structure of Bose condensate and its momentum distributions in 3-D anisotropic trap are considered by the solution of the modified non-linear Schrodinger equation. The results are compared with the corresponding properties of condensate in a harmonic trap without gravitational field.
On the transition between heterogeneous and homogeneous freezing
Directory of Open Access Journals (Sweden)
K. Gierens
2002-12-01
Full Text Available Box model simulations of an uplifting and adiabatically cooling cloud of aerosol have been performed in order to study the transition between cirrus formation dominated by homogeneous nucleation of ice to that dominated by heterogeneous nucleation. The aerosol was assumed to consist of an internal mixture of sulfuric acid solution droplets with inclusions of soot. The simulations show that the transition from heterogeneous to homogeneous nucleation occurs over a narrow range of soot concentration. Thus it seems to be possible to fix critical concentrations of heterogeneous ice nuclei which must be exceeded if heterogeneous freezing dominates cirrus formation. A formula has been derived that allows to compute the critical concentrations of heterogeneous ice nuclei as a function of temperature, updraft speed, ambient pressure, and supersaturation at which heterogeneous freezing occurs. Generally, homogeneous nucleation dominates in regions with updrafts stronger than 20 cmps, with the exception of heavily polluted areas which could be common in the northern hemisphere due to air traffic, where updrafts of the order 1 mps may be necessary to render heterogeneous nucleation unimportant. According to the present results it cannot be excluded that heterogeneous nucleation plays a more important role for cirrus formation in the northern midlatitudes than anywhere else. A possible consequence of these results is that air pollution may lead to a higher coverage of cirrus clouds, but then these clouds will be optically thinner than clouds formed by homogeneous freezing, with the exception of regions where condensation trails are frequent.
Quasi-single-mode homogeneous 31-core fibre
DEFF Research Database (Denmark)
Sasaki, Y.; Saitoh, S.; Amma, Y.;
2015-01-01
A homogeneous 31-core fibre with a cladding diameter of 230 μm for quasi-single-mode transmission is designed and fabricated. LP01-crosstalk of -38.4 dB/11 km at 1550 nm is achieved by using few-mode trench-assisted cores....
Solutions of D_\\alpha - 0 from Homogeneous Invariant Functions
Buccella, F.
2000-01-01
We prove that the existence of a homogeneous invariant of degree n for a representation of a semi-simple Lie group guarantees the existence of non-trivial solutions of D_{\\alpha} = 0: these correspond to the maximum value of the square of the invariant divided by the norm of the representation to the n^{th} power.
Solutions of $D_{\\alpha}$ = 0 from Homogeneous Invariant Functions
Buccella, F
2000-01-01
We prove that the existence of a homogeneous invariant of degree n for arepresentation of a semi-simple Lie group guarantees the existence ofnon-trivial solutions of D_{\\alpha} = 0: these correspond to the maximum valueof the square of the invariant divided by the norm of the representation to then^{th} power.
Class Management and Homogeneous Grouping in Kindergarten Literacy Instruction
Hong, Guanglei; Pelletier, Janette; Hong, Yihua; Corter, Carl
2010-01-01
The purpose of this study is two-fold. Firstly the authors examine, given the amount of time allocated to literacy instruction, whether homogeneous grouping helps improve class manageability over the kindergarten year and whether individual students' externalizing problem behaviors will decrease in tandem. Secondly, they investigate whether the…
A homogeneous superconducting magnet design using a hybrid optimization algorithm
International Nuclear Information System (INIS)
This paper employs a hybrid optimization algorithm with a combination of linear programming (LP) and nonlinear programming (NLP) to design the highly homogeneous superconducting magnets for magnetic resonance imaging (MRI). The whole work is divided into two stages. The first LP stage provides a global optimal current map with several non-zero current clusters, and the mathematical model for the LP was updated by taking into account the maximum axial and radial magnetic field strength limitations. In the second NLP stage, the non-zero current clusters were discretized into practical solenoids. The superconducting conductor consumption was set as the objective function both in the LP and NLP stages to minimize the construction cost. In addition, the peak–peak homogeneity over the volume of imaging (VOI), the scope of 5 Gauss fringe field, and maximum magnetic field strength within superconducting coils were set as constraints. The detailed design process for a dedicated 3.0 T animal MRI scanner was presented. The homogeneous magnet produces a magnetic field quality of 6.0 ppm peak–peak homogeneity over a 16 cm by 18 cm elliptical VOI, and the 5 Gauss fringe field was limited within a 1.5 m by 2.0 m elliptical region. (paper)
A homogeneous superconducting magnet design using a hybrid optimization algorithm
Ni, Zhipeng; Wang, Qiuliang; Liu, Feng; Yan, Luguang
2013-12-01
This paper employs a hybrid optimization algorithm with a combination of linear programming (LP) and nonlinear programming (NLP) to design the highly homogeneous superconducting magnets for magnetic resonance imaging (MRI). The whole work is divided into two stages. The first LP stage provides a global optimal current map with several non-zero current clusters, and the mathematical model for the LP was updated by taking into account the maximum axial and radial magnetic field strength limitations. In the second NLP stage, the non-zero current clusters were discretized into practical solenoids. The superconducting conductor consumption was set as the objective function both in the LP and NLP stages to minimize the construction cost. In addition, the peak-peak homogeneity over the volume of imaging (VOI), the scope of 5 Gauss fringe field, and maximum magnetic field strength within superconducting coils were set as constraints. The detailed design process for a dedicated 3.0 T animal MRI scanner was presented. The homogeneous magnet produces a magnetic field quality of 6.0 ppm peak-peak homogeneity over a 16 cm by 18 cm elliptical VOI, and the 5 Gauss fringe field was limited within a 1.5 m by 2.0 m elliptical region.
Laser Powered Homogeneous Decomposition of 2,2-Diethenylhexamethyltrisilane
Czech Academy of Sciences Publication Activity Database
Fajgar, Radek; Hassler, K.; Pola, Josef
2005-01-01
Roč. 73, č. 2 (2005), s. 284-289. ISSN 0165-2370 R&D Projects: GA AV ČR(CZ) IAA4072107 Institutional research plan: CEZ:AV0Z40720504 Keywords : 2,2-diethenylhexamethyltrisilane * homogeneous decomposition * mechanism Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 1.265, year: 2005
IMPACT OF COOKING HOMOGENEITY ON PULP STRENGTH PROPERTIES
Institute of Scientific and Technical Information of China (English)
Bofeng Mao
2004-01-01
Cooking homogeneity of kraft pulping can have significant impact on pulp strength properties. We have studied cooking homogeneity of two kraft digesters within Stora Enso. One of the digesters is a one-vessel hydraulic continuous digester (digester A)and the other one is a two-vessel vapor/liquor phase continuous digester (digester B). They are located in the same mill and use the same softwood chip quality. Due to the differences in chip pre-steaming and cooking facilities and conditions, significant differences in pulp strength properties, reject contents and kappa variations have been found between the pulps produced in the two digesters. Digester A has a modem chip bin with efficient pre-heating and air removal, whereas digester B has poor chip pre-steaming conditions. Our strength delivery studies show that although the two digesters produce pulps with the same kappa number and viscosity, the pulp produced in digester A has about 20% higher strength delivery, l%-unit (based on wood) lower reject content and lower kappa variations based on FTIR spectra analysis on pulp sheet than the pulp produced in digester B.Results of the studies indicate that more homogeneous cooking, i.e., lower lignin/kappa variation in the fibers, leads to improved pulp strength properties. Efficient chip pre-steaming is important/essential for achieving homogeneous cooking. Rebuilding the equipment for improving chip pre-steaming conditions of digester B is to be carried out.
Intergroup Attitudes of European American Children Attending Ethnically Homogeneous Schools
McGlothlin, Heidi; Killen, Melanie
2006-01-01
Intergroup attitudes were assessed in European American 1st-grade (M=6.99 years, SD=0.32) and 4th-grade (M=10.01 years, SD=0.36) children (N=138) attending ethnically homogeneous schools to test hypotheses about racial biases and interracial friendships. An Ambiguous Situations Task and an Intergroup Contact Assessment were administered to all…
Simple compactifications and polar decomposition of homogeneous real spherical spaces
DEFF Research Database (Denmark)
Knop, Friedrich; Krötz, Bernhard; Sayag, Eitan; Schlichtkrull, Henrik
2015-01-01
Let Z be an algebraic homogeneous space Z = G/H attached to real reductive Lie group G. We assume that Z is real spherical, i.e., minimal parabolic subgroups have open orbits on Z. For such spaces, we investigate their large scale geometry and provide a polar decomposition. This is obtained from...
RELAXATION OF FUNCTIONALS INVOLVING HOMOGENEOUS FUNCTIONS AND INVARIANCE OF ENVELOPES
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The authors compute the quasiconvex envelope of certain functions defined on the space Mmn of real m× n matrices via a homogeneous function on Mmn. They also deduce invariance properties for various convex envelopes from corresponding invariance properties satisfied by a function. Some applications related in particular to nonlinear elasticity are given.
Maximum absorption by homogeneous magneto-dielectric sphere
DEFF Research Database (Denmark)
Palvig, Michael Forum; Breinbjerg, Olav; Willatzen, Morten
2014-01-01
n order to obtain a benchmark for electromagnetic energy harvesting, we investigate the maximum absorption efficiency by a magneto-dielectric homogeneous sphere illuminated by a plane wave, and we arrive at several novel results. For electrically small spheres we show that the optimal relative......–Mie theory combined with the optical theorem....
Anything goes with heterogeneous, but not always with homogeneous oligopoly
D. Furth
2009-01-01
Corchón and Mas-Colell [1996. On the stability of best reply and gradient systems with applications to imperfectly competitive models. Economics Letters 51, 59-65] showed that in heterogeneous oligopoly (almost) everything is possible. In order to obtain a similar result for homogeneous oligopoly, e
Homogeneous catalytic hydrogenations of complex carbonaceous substrates. [16 references
Energy Technology Data Exchange (ETDEWEB)
Cox, J L; Wilcox, W A; Roberts, G L
1976-11-05
Results of homogeneous catalytic hydrogenation of complex unsaturated substrates including coal and coal-derived materials are reported, with organic soluble molecular complexes as catalysts. Among the substrates used were Hvab coal, solvent-refined coal, and COED pyrolysate. The hydrogenations were carried out in an autoclave. The results are summarized in tables.
Missing data analysis and homogeneity test for Turkish precipitation series
Indian Academy of Sciences (India)
Mahmut Firat; Fatih Dikbas; A Cem Koç; Mahmud Gungor
2010-12-01
In this study, missing value analysis and homogeneity tests were conducted for 267 precipitation stations throughout Turkey. For this purpose, the monthly and annual total precipitation records at stations operated by Turkish State Meteorological Service (DMI) from 1968 to 1998 were considered. In these stations, precipitation records for each month was investigated separately and the stations with missing values for too many years were eliminated. The missing values of the stations were completed by Expectation Maximization (EM) method by using the precipitation records of the nearest gauging station. In this analysis, 38 stations were eliminated because they had missing values for more than 5 years, 161 stations had no missing values and missing precipitation values were completed in the remaining 68 stations. By this analysis, annual total precipitation data were obtained by using the monthly values. These data should be hydrologically and statistically reliable for later hydrological, meteorological, climate change modelling and forecasting studies. For this reason, Standard Normal Homogeneity Test (SNHT), (Swed–Eisenhart) Runs Test and Pettitt homogeneity tests were applied for the annual total precipitation data at 229 gauging stations from 1968 to 1998. The results of each of the testing methods were evaluated separately at a signiﬁcance level of 95% and the inhomogeneous years were determined. With the application of the aforementioned methods, inhomogeneity was detected at 50 stations of which the natural structure was deteriorated and 179 stations were found to be homogeneous.
Hydrologic homogeneous regions using monthly Streamflow in Turkey
Kahya, Ercan; Demirel, Mehmet C.; Beg, Osman A.
2008-01-01
Cluster analysis of gauged streamflow records into homogeneous and robust regions is an important tool for the characterization of hydrologic systems. In this paper we applied the hierarchical cluster analysis to the task of objectively classifying streamflow data into regions encompassing similar s
Stability of rehydrated Mycoplasma gallisepticum vaccine homogeneity over time
Proper vaccine application is required to maximize the results of the vaccination, with maintenance of a homogenous solution is critical to obtain uniform results. This study was designed to analyze the need for continued mixing of a Mycoplasma gallisepticum vaccine solution in order to maintain a ...
Size-dependent homogenized diffusion parameters for a finite lattice
International Nuclear Information System (INIS)
A numerical technique is reported for solving the transcendental equation for unknown Ysub(n+1). The solution is expressed in terms of quantities related to Ysub(n). This is an iterative reversion technique which has already been proven to converge rapidly in the homogeneous slab problem considered herein. (author)
Gauge freedom in perfect fluid spatially homogeneous spacetimes
International Nuclear Information System (INIS)
The class of reference systems compatible with the symmetry of a spatially homogeneous perfect fluid spacetime is discussed together with the associated class of symmetry adapted comoving ADM frames (or computational frames). The fluid equations of motion are related to the four functions on the space of fluid flow lines discovered by Taub and which characterize an isentropic flow. (Auth.)
Transport properties of fullerene-polyphenylene oxide homogeneous membranes
Czech Academy of Sciences Publication Activity Database
Polotskaya, G.; Biryulin, Yu.; Pientka, Zbyněk; Brožová, Libuše; Bleha, Miroslav
2004-01-01
Roč. 12, č. 1 (2004), s. 371-376. ISSN 1536-383X R&D Projects: GA AV ČR KSK4050111 Keywords : fulleren e * polyphenylene oxide * homogeneous membranes Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.117, year: 2004
Homogeneity of Danish environmental and clinical isolates of Shewanella algae
DEFF Research Database (Denmark)
Vogel, Birte Fonnesbech; Holt, H.M.; Gerner-Smidt, P.; Bundvad, A.; Søgaard, P.; Gram, Lone
2000-01-01
Danish isolates of Shewanella algae constituted by whole-cell protein profiling a very homogeneous group, and no clear distinction was seen between strains from the marine environment and strains of clinical origin. Although variation between all strains was observed by ribotyping and random...
Homogenization of viscoplastic constitutive laws within a phase field approach
de Rancourt, Victor; Ammar, Kais; Appolaire, Benoît; Forest, Samuel
2016-03-01
The present work provides an original consistent framework for combining different constitutive laws, possibly nonlinear, within diffuse interface models (phase field) by homogenization rather than by mixing the material parameters, such as to offer a greater flexibility. The framework relies on the choice of relevant thermodynamic potentials such that the homogenization schemes are natural choices in the thermodynamic formulation. Thus, it justifies previously proposed classic schemes (Ammar et al., 2009b) and gives clues to explore new schemes (Durga et al., 2013; Mosler et al., 2014) by defining relevant potentials. The proposed framework is illustrated by addressing two issues. First, Reuss and Voigt homogenization schemes are shown to deliver the same kinetics of diffusion-controlled transformations in the pure elastic case in the limit of vanishing diffuse interface width. Second, using the Voigt homogenization scheme, we demonstrate that the influence of viscoplasticity, either isotropic or crystalline, on diffusion-controlled transformations is non-trivial and cannot be inferred from simple qualitative arguments. Depending on the competition between the time scales of diffusion and viscoplasticity, the growth kinetics may exhibit intermediate behaviors between purely chemical and elastic cases. Moreover, it is shown how viscoplasticity can change the morphological stability of growing circular precipitates.
Fabrication of Beam Homogenizers in Quartz by Laser Micromachining
Energy Technology Data Exchange (ETDEWEB)
Kopitkovas, G.; Lippert, T.; David, C.; Gobrecht, J.; Wokaun, A.
2004-03-01
A one step micromachining process, which utilizes laser assisted chemical wet etching and projection of a diffractive gray tone phase masks is applied to fabricate 3 - dimensional microstructures (such as planoconvex or Fresnel microlenses) in UV transparent materials. Arrays of microlenses in quartz are tested as a beam homogenizers for quadrupled Nd:YAG laser. (author)
Prognosis and optimization of homogeneous Markov message handling networks
Czech Academy of Sciences Publication Activity Database
Boček, Pavel; Feglar, T.; Janžura, Martin; Vajda, Igor
2001-01-01
Roč. 37, č. 6 (2001), s. 625-646. ISSN 0023-5954 R&D Projects: GA ČR GA102/99/1137 Institutional research plan: AV0Z1075907 Keywords : homogeneous Markov networks Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 0.316, year: 2001
How to determine composite material properties using numerical homogenization
DEFF Research Database (Denmark)
Andreassen, Erik; Andreasen, Casper Schousboe
2014-01-01
Numerical homogenization is an efficient way to determine effective macroscopic properties, such as the elasticity tensor, of a periodic composite material. In this paper an educational description of the method is provided based on a short, self-contained Matlab implementation. It is shown how the...
Quantum gravity stability of isotropy in homogeneous cosmology
International Nuclear Information System (INIS)
It has been shown that anisotropy of homogeneous spacetime described by the general Kasner metric can be damped by quantum fluctuations coming from perturbative quantum gravity in one-loop approximation. Also, a formal argument, not limited to one-loop approximation, is put forward in favor of stability of isotropy in the exactly isotropic case.
Homogeneity of Moral Judgment? Apprentices Solving Business Conflicts.
Beck, Klaus; Heinrichs, Karin; Minnameier, Gerhard; Parche-Kawik, Kirsten
In an ongoing longitudinal study that started in 1994, the moral development of business apprentices is being studied. The focal point of this project is a critical analysis of L. Kohlberg's thesis of homogeneity, according to which people should judge every moral issue from the point of view of their "modal" stage (the most frequently used stage…
Interfacial Thermodynamics of Coexisting Aqueous Polymer Solutions
Vis, M.
2015-01-01
Phase separation is commonly observed when two different polymers are present in aqueous solution, forming aqueous two-phase systems which typically consist for 90% of water. It is demonstrated that the presence of charge on one of the polymers results in an electric potential difference between the
Homogeneous Electrocatalytic Reduction of Carbon Dioxide to Carbon Monoxide by Ni(cyclam)
Froehlich, Jesse Dan
The homogeneous electrochemical reduction of CO2 by the molecular catalyst [Ni(cyclam)]2+ was studied by electrochemistry and infrared spectroelectrochemistry. This catalyst has been previously shown to have increased CO2 reduction activity when adsorbed on a mercury electrode. The homogeneous reactivity, without a mercury electrode, was often ignored in the literature. Ni(cyclam) was found to efficiently and selectively produce CO at moderate overpotentials in both aqueous and mixed organic solvent systems in a homogenous fashion at an inert glassy carbon electrode. Methylated analogs of Ni(cyclam) were also studied and observed to have more positive reduction potentials and attenuated CO2 reduction activity. The electrochemical kinetics were probed by varying CO2 substrate and proton concentrations. Products of CO2 reduction are observed in infrared spectra obtained from spectroelectrochemical experiments. The two major species observed were a Ni(I) carbonyl, [Ni(cyclam)(CO)]+, and a Ni(II) coordinated bicarbonate, [Ni(cyclam)(CO2OH)] +. The rate-limiting step during electrocatalysis was determined to be CO loss from the deactivated species, [Ni(cyclam)(CO)]+, to produce the active catalyst, [Ni(cyclam)]+. Another macrocyclic complex, [Ni(TMC)]+, was deployed as a CO scavenger in order to inhibit the deactivation of [Ni(cyclam)] + by CO. Addition of the CO scavenger was shown to dramatically increase the catalytic current observed for CO2 reduction by [Ni(cyclam)] +. Evidence for the [Ni(TMC)]+ acting as a CO scavenger includes the observation of [Ni(TMC)(CO)]+ by IR. Density functional theory calculations, probing the optimized geometry of the [Ni(cyclam)(CO)] + species, are also presented. These findings have implications on the increased activity for CO2 reduction when [Ni(cyclam)] + is adsorbed on a mercury electrode. The [Ni(cyclam)(CO)] + structure has significant distortion of the Ni center out of the plane of the cyclam nitrogens. This distortion
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Damping the neutrino flavor pendulum by breaking homogeneity
Mangano, Gianpiero; Mirizzi, Alessandro; Saviano, Ninetta
2014-04-01
The most general case of self-induced neutrino flavor evolution is described by a set of kinetic equations for a dense neutrino gas evolving in both space and time. Solutions of these equations have been typically worked out assuming that either the time (in the core-collapse supernova environment) or space (in the early Universe) homogeneity in the initial conditions is preserved through the evolution. In these cases, one can gauge away the homogeneous variable and reduce the dimensionality of the problem. In this paper, we investigate whether small deviations from an initial postulated homogeneity can be amplified by the interacting neutrino gas, leading to a new flavor instability. To this end, we consider a simple two-flavor isotropic neutrino gas evolving in time, and initially composed by only νe and ν ¯e with equal densities. In the homogeneous case, this system shows a bimodal instability in the inverted mass hierarchy scheme, leading to the well-studied flavor pendulum behavior. This would lead to periodic pair conversions νeν ¯e↔νxν ¯x. To break space homogeneity, we introduce small amplitude space-dependent perturbations in the matter potential. By Fourier transforming the equations of motion with respect to the space coordinate, we then numerically solve a set of coupled equations for the different Fourier modes. We find that even for arbitrarily tiny inhomogeneities, the system evolution runs away from the stable pendulum behavior: the different modes are excited and the space-averaged ensemble evolves towards flavor equilibrium. We finally comment on the role of a time decaying neutrino background density in weakening these results.
Recent advances in the understanding of homogeneous dielectric barrier discharges
Massines, F.; Gherardi, N.; Naudé, N.; Ségur, P.
2009-08-01
This paper is a state of the art of the understanding on the physics of homogeneous dielectric barrier discharges at atmospheric pressure. It is based on the analysis of present and previous work about the behavior of these discharges and the conditions to get them. Mechanisms controlling the homogeneity during gas breakdown and discharge development are successively discussed. The breakdown has to be a Townsend one, the ionization has to be slow enough to avoid a large avalanche development. During the breakdown, the discharge homogeneity is related to the ratio of the secondary emission at the cathode (γ coefficient) on the ionization in the gas bulk (α coefficient). Higher is this ratio, higher is the pressure × gas gap product (Pd) value for which a Townsend breakdown is obtained. Among the phenomena enhancing the secondary emission there is the negative charge of the dielectric on the cathode surface, the trapping of ions in the gas and the existence of excited state having a long lifetime compared to the time between two consecutive discharges. The first phenomenon is always present when the electrodes are covered by a solid dielectric, the second one is related to the formation of a positive column and the third one is specific of the gas. During the discharge development, the homogeneity is mainly controlled by the voltage or the current imposed by the electrical circuit/electrode configuration and by the gas ability to be slowly ionized. Larger is the contribution of a multiple step ionization process like Penning ionization, higher will be the working domain of the discharge. A decrease of the gas voltage during the discharge development is a solution to enhance the contribution of this process. After 20 years of research a lot of mechanisms have been understood however there is still open questions like the nature of the Inhibited homogeneous DBD, surface energy transfers, role of attachment and detachment...
Magnetic stimulation for non-homogeneous biological structures
Directory of Open Access Journals (Sweden)
Papazov Sava P
2002-09-01
Full Text Available Abstract Background Magnetic stimulation has gained relatively wide application in studying nervous system structures. This technology has the advantage of reduced excitation of sensory nerve endings, and hence results in quasi-painless action. It has become clinically accepted modality for brain stimulation. However, theoretical and practical solutions for assessment of induced current distribution need more detailed and accurate consideration. Some possible analyses are proposed for distribution of the current induced from excitation current contours of different shape and disposition. Relatively non-difficult solutions are shown, applicable for two- and three-dimensional analysis. Methods The boundary conditions for field analysis by the internal Dirichlet problem are introduced, based on the vector potential field excited by external current coils. The feedback from the induced eddy currents is neglected. Finite element modeling is applied for obtaining the electromagnetic fields distribution in a non-homogeneous domain. Results The distributions were obtained in a non-homogeneous structure comprised of homogeneous layers. A tendency was found of the induced currents to follow paths in lower resistivity layers, deviating from the expected theoretical course for a homogeneous domain. Current density concentrations occur at the boundary between layers, suggesting the possibility for focusing on, or predicting of, a zone of stimulation. Conclusion The theoretical basis and simplified approach for generation of 3D FEM networks for magnetic stimulation analysis are presented, applicable in non-homogeneous and non-linear media. The inconveniences of introducing external excitation currents are avoided. Thus, the possibilities are improved for analysis of distributions induced by time-varying currents from contours of various geometry and position with respect to the medium.
Metal separations using aqueous biphasic partitioning systems
International Nuclear Information System (INIS)
Aqueous biphasic extraction (ABE) processes offer the potential for low-cost, highly selective separations. This countercurrent extraction technique involves selective partitioning of either dissolved solutes or ultrafine particulates between two immiscible aqueous phases. The extraction systems that the authors have studied are generated by combining an aqueous salt solution with an aqueous polymer solution. They have examined a wide range of applications for ABE, including the treatment of solid and liquid nuclear wastes, decontamination of soils, and processing of mineral ores. They have also conducted fundamental studies of solution microstructure using small angle neutron scattering (SANS). In this report they review the physicochemical fundamentals of aqueous biphase formation and discuss the development and scaleup of ABE processes for environmental remediation
Synthesis of Starch-Stabilized Ag Nanoparticles and Hg2+Recognition in Aqueous Media
Directory of Open Access Journals (Sweden)
Fan Yingju
2009-01-01
Full Text Available Abstract The starch-stabilized Ag nanoparticles were successfully synthesized via a reduction approach and characterized with SPR UV/Vis spectroscopy, TEM, and HRTEM. By utilizing the redox reaction between Ag nanoparticles and Hg2+, and the resulted decrease in UV/Vis signal, we develop a colorimetric method for detection of Hg2+ion. A linear relationship stands between the absorbance intensity of the Ag nanoparticles and the concentration of Hg2+ion over the range from 10 ppb to 1 ppm at the absorption of 390 nm. The detection limit for Hg2+ions in homogeneous aqueous solutions is estimated to be ~5 ppb. This system shows excellent selectivity for Hg2+over other metal ions including Na+, K+, Ba2+, Mg2+, Ca2+, Fe3+, and Cd2+. The results shown herein have potential implications in the development of new colorimetric sensors for easy and selective detection and monitoring of mercuric ions in aqueous solutions.
Directory of Open Access Journals (Sweden)
Diana Guzman-Villanueva
2013-01-01
Full Text Available Curcumin, a yellow polyphenol derived from the turmeric Curcuma longa, has been associated with a diverse therapeutic potential including anti-inflammatory, antioxidant, antiviral, and anticancer properties. However, the poor aqueous solubility and low bioavailability of curcumin have limited its potential when administrated orally. In this study, curcumin was encapsulated in a series of novel nano-microparticulate systems developed to improve its aqueous solubility and stability. The nano-microparticulate systems are based entirely on biocompatible, biodegradable, and edible polymers including chitosan, alginate, and carrageenan. The particles were synthesized via ionotropic gelation. Encapsulating the curcumin into the hydrogel nanoparticles yielded a homogenous curcumin dispersion in aqueous solution compared to the free form of curcumin. Also, the in vitro release profile showed up to 95% release of curcumin from the developed nano-microparticulate systems after 9 hours in PBS at pH 7.4 when freeze-dried particles were used.
Filippini, G; Bonal, C; Malfreyt, P
2014-05-14
In this study, the thermodynamic properties of association of some inorganic ions (ClO4(-) and SO4(2-)) with β-cyclodextrins (β-CD) in aqueous solution are determined under both free β-CD and surface confined β-CD conditions using atomistic simulations. The potential of mean force (PMF) is calculated as a function of the environment and the thermodynamic properties of association are deduced by integrating the free energy profiles. No inclusion complex between SO4(2-) and β-CD is detected. Nevertheless, the PMF curve obtained for gold-confined CD seems to evidence a small minimum at a larger separation distance that shows specific interactions such as hydrogen bonding outside the cavity. As concerns ClO4(-), our simulations reveal the formation of an inclusion complex with free β-CD in perfect agreement with the available experimental results. Nevertheless, we do not detect any formation of the host-guest inclusion complex under heterogeneous conditions. Finally, the differences observed as a function of the anions are interpreted through an atomistic description. The general trend of weaker complex stabilities with the increasing free energy of hydration of the anions is found in homogeneous systems. PMID:24676343
Electro-osmosis in kaolinite with pH-dependent surface charge modelling by homogenization.
Lima, Sidarta A; Murad, Marcio A; Moyne, Christian; Stemmelen, Didier
2010-03-01
A new three-scale model to describe the coupling between pH-dependent flows and transient ion transport, including adsorption phenomena in kaolinite clays, is proposed. The kaolinite is characterized by three separate nano/micro and macroscopic length scales. The pore (micro)-scale is characterized by micro-pores saturated by an aqueous solution containing four monovalent ions and charged solid particles surrounded by thin electrical double layers. The movement of the ions is governed by the Nernst-Planck equations, and the influence of the double layers upon the flow is dictated by the Helmholtz-Smoluchowski slip boundary condition on the tangential velocity. In addition, an adsorption interface condition for the Na+ transport is postulated to capture its retention in the electrical double layer. The two-scale nano/micro model including salt adsorption and slip boundary condition is homogenized to the Darcy scale and leads to the derivation of macroscopic governing equations. One of the notable features of the three-scale model is there construction of the constitutive law of effective partition coefficient that governs the sodium adsorption in the double layer. To illustrate the feasibility of the three-scale model in simulating soil decontamination by electrokinetics, the macroscopic model is discretized by the finite volume method and the desalination of a kaolinite sample by electrokinetics is simulated. PMID:20209253
Cognitive Medical Multiagent Systems
Directory of Open Access Journals (Sweden)
Barna Iantovics
2010-01-01
Full Text Available The development of efficient and flexible agent-based medical diagnosis systems represents a recent research direction. Medical multiagent systems may improve the efficiency of traditionally developed medical computational systems, like the medical expert systems. In our previous researches, a novel cooperative medical diagnosis multiagent system called CMDS (Contract Net Based Medical Diagnosis System was proposed. CMDS system can solve flexibly a large variety of medical diagnosis problems. This paper analyses the increased intelligence of the CMDS system, which motivates its use for different medical problem’s solving.
Present status of the use of LEU in aqueous reactors to produce Mo-99
Energy Technology Data Exchange (ETDEWEB)
Ball, Russell M. [Technology Commercialization International, Lynchburg, VA (United States); E-mail: 76130.1301@compuserve.com; Pavshook, V.A.; Khvostionov, V.Ye. [Russian Research Centre Kurchatov Inst., Moscow (Russian Federation)
1998-07-01
An operating aqueous homogeneous reactor, the ARGUS at Kurchatov Institute, has been used to produce fission product molybdenum-99 (Mo-99), widely used in nuclear medicine to produce technetium-99m (Tc-99m). The Mo-99 has been extracted from the sulfate solution using an organic sorbent after operation at 1 kW/liter. after purification, the material has been assayed and the result is well within required specification of the USPharmacopaeia. Operation calculation are presented to show the sources and quantity of alpha activity when LEU is used. (author)
Institute of Scientific and Technical Information of China (English)
朱文庆; 瞿芳; 陈浩军; 李卓; 刘斌
2014-01-01
SmOHCO3micro/nano particles were prepared in water/oil (W/O) reverse microemulsion composed of cetyltrimethyl ammonium bromide (CTAB), n-octane, n-butanol, Sm(NO3)3·6H2O and urea aqueous solution by the coupling route of homogeneous precipitation with microemulsion. The nanoparticles were characterized and analyzed by X-ray powder diffraction (XRD), thermal gravimetric and differential thermal gravimetric analysis (TG-DTG), Fourier transform infrared absorption spectra (FT-IR) and scan-ning electron microscope (SEM). The results showed that the phase SmOHCO3 micro/nano particles was in agreement with pure or-thorhombic phase. The different morphologies of SmOHCO3 micro/nano particles with good monodispersity and size were obtained by regulating the reaction temperature and reaction time. Possible formation mechanisms of the morphological structure of SmO-HCO3 were proposed and discussed.
MEDICAL ETHICS COURSE IMPROVES MEDICAL PROFESSIONALISM: MEDICAL STUDENTS´ OPINIONS
Directory of Open Access Journals (Sweden)
Abdolreza Sotoodeh Jahromi
2014-01-01
Full Text Available Training physicians who are expert in many medical aspects is the most improtant mission of medical universities. One of these aspects, is professional behavior achievement. One of the important goals in training of ethics, is recognition of conflicts in different parts of ethics and having logical viewpoint for resolving and analyzing these conflicts. This descriptive and analytical study was done to evaluate the efficacy of medical ethics education in medical students´ professional attitudes improvement. One hundred and two medical students were selected randomly in different steps of education and were questioned and their opinions correlation with stage of education and gender were evaluated. There was a significant difference between female viewpoint (in roles of ethic course which is presented in preclinical step in professional attitude improvement (P = 0.009 and also a significant difference was seen in the viewpoint score between student stage with intern stage (P = 0.031. Medical students in educational student stage believe ethic course improve medical professionalism. Since there is no special course to train medical students in professionalism, some interventions are required in this field to improve this aspect of physicians' professional life.
Mixing and chemical reaction in sheared and nonsheared homogeneous turbulence
Leonard, Andy D.; Hill, James C.
1992-01-01
Direct numerical simulations were made to examine the local structure of the reaction zone for a moderately fast reaction between unmixed species in decaying, homogeneous turbulence and in a homogeneous turbulent shear flow. Pseudospectral techniques were used in domains of 64 exp 3 and higher wavenumbers. A finite-rate, single step reaction between non-premixed reactants was considered, and in one case temperature-dependent Arrhenius kinetics was assumed. Locally intense reaction rates that tend to persist throughout the simulations occur in locations where the reactant concentration gradients are large and are amplified by the local rate of strain. The reaction zones are more organized in the case of a uniform mean shear than in isotropic turbulence, and regions of intense reaction rate appear to be associated with vortex structures such as horseshoe vortices and fingers seen in mixing layers. Concentration gradients tend to align with the direction of the most compressive principal strain rate, more so in the isotropic case.
Can photonic crystals be homogenized in higher bands?
Markel, Vadim A
2015-01-01
We consider the conditions under which photonic crystals (PCs) can be viewed as electromagnetically homogeneous at frequencies in the higher photonic bands and, in particular, near the higher-order $\\Gamma$-points. We show that the observation that a purely real isofrequency line of the PC is close to a mathematical circle is insufficient for establishing homogenizability. Complex dispersion points must be included into consideration even in the case of strictly non-absorbing materials. By applying a more careful analysis to the dispersion relations and complex isofrequency lines, we have found that two-dimensional PCs with $C_4$ and $C_6$ symmetries are not electromagnetically homogeneous in the higher photonic bands in spite of the fact that, at some particular frequencies, the real isofrequency lines of these PCs can be circular with high precision.
Neutron transport equation - indications on homogenization and neutron diffusion
International Nuclear Information System (INIS)
In PWR nuclear reactor, the practical study of the neutrons in the core uses diffusion equation to describe the problem. On the other hand, the most correct method to describe these neutrons is to use the Boltzmann equation, or neutron transport equation. In this paper, we give some theoretical indications to obtain a diffusion equation from the general transport equation, with some simplifying hypothesis. The work is organised as follows: (a) the most general formulations of the transport equation are presented: integro-differential equation and integral equation; (b) the theoretical approximation of this Boltzmann equation by a diffusion equation is introduced, by the way of asymptotic developments; (c) practical homogenization methods of transport equation is then presented. In particular, the relationships with some general and useful methods in neutronic are shown, and some homogenization methods in energy and space are indicated. A lot of other points of view or complements are detailed in the text or the remarks
Representations of Homogeneous Quantum Lévy Fields
Indian Academy of Sciences (India)
V P Belavkin; L Gregory
2006-11-01
We study homogeneous quantum Lévy processes and fields with independent additive increments over a noncommutative ∗-monoid. These are described by infinitely divisible generating state functionals, invariant with respect to an endomorphic injective action of a symmetry semigroup. A strongly covariant GNS representation for the conditionally positive logarithmic functionals of these states is constructed in the complex Minkowski space in terms of canonical quadruples and isometric representations on the underlying pre-Hilbert field space. This is of much use in constructing quantum stochastic representations of homogeneous quantum Lévy fields on Itô monoids, which is a natural algebraic way of defining dimension free, covariant quantum stochastic integration over a space-time indexing set.
The IDSA and the homogeneous sphere: Issues and possible improvements
Michaud, Jérôme
2016-01-01
In this paper, we are concerned with the study of the Isotropic Diffusion Source Approximation (IDSA) (Baxter et al., Phys. Rev. E 73, 046118, 2006) of radiative transfer. After having recalled well-known limits of the radiative transfer equation, we present the IDSA and adapt it to the case of the homogeneous sphere. We then show that for this example the IDSA suffers from severe numerical difficulties. We argue that these difficulties originate in the min-max switch coupling mechanism used in the IDSA. To overcome this problem we reformulate the IDSA to avoid the problematic coupling. This allows us to access the modeling error of the IDSA for the homogeneous sphere test case. The IDSA is shown to overestimate the streaming component, hence we propose a new version of the IDSA which is numerically shown to be more accurate than the old one. Analytical results and numerical tests are provided to support the accuracy of the new proposed approximation.
The role of material in homogeneities in biological growth
Directory of Open Access Journals (Sweden)
Grillo A.
2005-01-01
Full Text Available We investigate the influence of the material in homogeneities that are generated by an isotropic growth on the source of mass acting within a growing living tissue. In order to do that, we need to study the interaction between these material in homogeneities and the chemical agents dissolved within the tissue. For this purpose, we use some ideas and methods from Condensed Matter Physics (e.g., the Path Integral technique employed in modeling Brownian processes and apply them to the Continuum Mechanics description of volumetric Growth. We believe that this approach may provide new physical insight into the interactions between the macroscopic dynamics of living systems and the evolution of the subsystems which activate biological processes.
Homogenization and simulation for compositional flow in naturally fractured reservoirs
Chen, Zhangxin
2007-02-01
A dual porosity model of multidimensional, multicomponent, multiphase flow in naturally fractured reservoirs is derived by the mathematical theory of homogenization. A fully compositional model is considered where there are N chemical components, each of which may exist in any or all of the three phases: gas, oil, and water. Special attention is paid to developing a general approach to incorporating gravitational forces, pressure gradient effects, and effects of mass transfer between phases. In particular, general equations for the interactions between matrix and fracture systems are obtained under homogenization by a careful scaling of these effects. Using this dual porosity compositional model, numerical experiments are reported for the benchmark problems of the sixth comparative solution project organized by the society of petroleum engineers.
Locally homogeneous but globally inhomogeneous spaces in cosmology
International Nuclear Information System (INIS)
Friedman-Robertson-Walker cosmologies has been studied with nontrivial spatial sections. These models allow cosmic space to be closed (finite and boundless) even if the density ratio (OMEGA) is not greater than unity. The price one pags for thus satisfying closure of space postulate is that the new spatial sections are multiply connected, and in many cases no longer globally homogeneous, though still locally so. This implies that the cosmological principle has to be reinterpreted, but there are interesting, potentially observable consequences of this modification. The homogeneity or inhomogeneity of a closed space of constant curvature is known from sophisticated mathematical theory. But it is convenient to have a more graphical, observationally meaningflul criterion to verify this property. Such a test of inhomogeneity is proposed in terms of geodesic loops. Then the mentioned reinterpretation of the cosmological principle is discussed. (author)
Computer modeling of homogenization of boric acid in IRIS pressurizer
International Nuclear Information System (INIS)
Integral layout of nuclear reactor IRIS makes possible the elimination of the spray system; which is usually used to mitigate in-surge transient and help to boron homogenization. The study of transients with deficiencies in the boron homogenization in this technology is very important, because they can cause disturbances in the reactor power and insert a strong reactivity in the core. The aim of the present research is to model the IRIS pressurizer using the CFX code searching for designs alternatives that guaranteed its intrinsic security, focused on the phenomena before mentioned. A symmetric tri dimensional model equivalent to 1/8 of the total geometry was adopted to reduce mesh size and minimize processing time. The relationships are programmed and incorporated into the code. This paper discusses the model developed and the behavior of the system for representative transients sequences. The results of the analyzed IRIS transients could be applied to the design of the pressurizer internal structures and components. (Author)
Electrical properties of vanadium carbide in the homogeneity region
Energy Technology Data Exchange (ETDEWEB)
Savin, V.I.; Spivak, I.I.; Topil' skij, N.D.; Rystsov, V.N.
1983-07-01
The results of investigations into electric, thermoelectric and galvanomagnetic properties in the region of vanadium carbide homogeneity in the 300-1500 K range are presented. The character of conductivity in the region of vanadium carbide homogeneity is not shown to be uniform: samples of VCsub(0.88), VCsub(0.84), VCsub(0.75) have metallic type of conductivity, the VCsub(0.75) sample displays semiconductor properties. Extrema conditioned by the effect of V/sub 8/C/sub 7/, V/sub 6/C/sub 5/, V/sub 4/C/sub 3/ carbide phase ordering are observed on concentration dependences of electric resistance, thermo-e. m.f., Hall constant. Temperature of order-disorder transformation by temperature dependences of electric resistance and thermo-e.m.f. makes up 1370-1420 K.
Homogeneous modification of carbon nanotubes with cellulose acetate
Institute of Scientific and Technical Information of China (English)
Gang Ke
2009-01-01
An efficient strategy that comprised shorten, chain extension, active groups introducing and homogeneous reaction tactics, was adopted to modify multiwalled carbon nanotubes (MWNTs) with cellulose acetate (CA). Specially, by utilizing 2,4,6-trichloro-1,3,5-triazine, a reactive intermediate of the MWNTs (MWNT-triazine) was obtained. Suitable solubility of the MWNT-triazine helps make the homogeneous modification become reality. Detailed characterizations further verified that reaction between chloride atoms in the MWNT-triazine and hydroxyl groups in the CA had contributed to the formation of MWNT-CA conjugates. The novel MWNT-CA consists of carbon (76.3%), oxygen (18.4%) and nitrogen (5.3%). With a nanotube-attached CA content of 42.8 wt%, the MWNT-CA is readily soluble in DMSO, NME DMF and DMAc. Confirmation of the CA-based modification route might lead to studies aiming for specific sorption and isolation.
Examination of homogeneity of selected Irish pooling groups
Directory of Open Access Journals (Sweden)
S. Das
2011-03-01
Full Text Available Flood frequency analysis is a necessary and important part of flood risk assessment and management studies. Regional flood frequency methods, in which flood data from groups of catchments are pooled together in order to enhance the precision of flood estimates at project locations, is an accepted part of such studies. This enhancement of precision is based on the assumption that catchments so pooled together are homogeneous in their flood producing properties. If homogeneity is assured then a homogeneous pooling group of sites lead to a reduction in the error of quantile estimates, relative to estimators based on single at-site data series alone. Homogeneous pooling groups are selected by using a previously nominated rule and this paper examines how effective one such rule is in selecting homogeneous groups. In this paper a study, based on annual maximum series obtained from 85 Irish gauging stations, examines how successful a common method of identifying pooling group membership is in selecting groups that actually are homogeneous. Each station has its own unique pooling group selected by use of a Euclidean distance measure in catchment descriptor space, commonly denoted d_{ij} and with a minimum of 500 station years of data in the pooling group. It was found that d_{ij} could be effectively defined in terms of catchment area, mean rainfall and baseflow index. The study then investigated how effective this selected method is in selecting groups of catchments that are actually homogenous as indicated by their L-Cv values. The sampling distribution of L-CV (t_{2} in each pooling group and the 95% confidence limits about the pooled estimate of t_{2} are obtained by simulation. The t_{2} values of the selected group members are compared with these confidence limits both graphically and numerically. Of the 85 stations, only 1 station's pooling group members have
Homogenization of long fiber reinforced composites including fiber bending effects
Poulios, Konstantinos; Niordson, Christian F.
2016-09-01
This paper presents a homogenization method, which accounts for intrinsic size effects related to the fiber diameter in long fiber reinforced composite materials with two independent constitutive models for the matrix and fiber materials. A new choice of internal kinematic variables allows to maintain the kinematics of the two material phases independent from the assumed constitutive models, so that stress-deformation relationships, can be expressed in the framework of hyper-elasticity and hyper-elastoplasticity for the fiber and the matrix materials respectively. The bending stiffness of the reinforcing fibers is captured by higher order strain terms, resulting in an accurate representation of the micro-mechanical behavior of the composite. Numerical examples show that the accuracy of the proposed model is very close to a non-homogenized finite-element model with an explicit discretization of the matrix and the fibers.
Homogenization of long fiber reinforced composites including fiber bending effects
DEFF Research Database (Denmark)
Poulios, Konstantinos; Niordson, Christian Frithiof
2016-01-01
This paper presents a homogenization method, which accounts for intrinsic size effects related to the fiber diameter in long fiber reinforced composite materials with two independent constitutive models for the matrix and fiber materials. A new choice of internal kinematic variables allows to...... maintain the kinematics of the two material phases independent from the assumed constitutive models, so that stress-deformation relationships, can be expressed in the framework of hyper-elasticity and hyper-elastoplasticity for the fiber and the matrix materials respectively. The bending stiffness of the...... reinforcing fibers is captured by higher order strain terms, resulting in an accurate representation of the micro-mechanical behavior of the composite. Numerical examples show that the accuracy of the proposed model is very close to a non-homogenized finite-element model with an explicit discretization of the...
Homogeneous Catalysis with Metal Complexes Fundamentals and Applications
Duca, Gheorghe
2012-01-01
The book about homogeneous catalysis with metal complexes deals with the description of the reductive-oxidative, metal complexes in a liquid phase (in polar solvents, mainly in water, and less in nonpolar solvents). The exceptional importance of the redox processes in chemical systems, in the reactions occuring in living organisms, the environmental processes, atmosphere, water, soil, and in industrial technologies (especially in food-processing industries) is discussed. The detailed practical aspects of the established regularities are explained for solving the specific practical tasks in various fields of industrial chemistry, biochemistry, medicine, analytical chemistry and ecological chemistry. The main scope of the book is the survey and systematization of the latest advances in homogeneous catalysis with metal complexes. It gives an overview of the research results and practical experience accumulated by the author during the last decade.
Voigt waves in electro-optic homogenized composite materials
Mackay, Tom G.
2014-08-01
A study was undertaken into Voigt wave propagation in a homogenized composite material (HCM). The HCM investigated arose from a porous electro-optic host material infiltrated by a fluid of refractive index na, considered in the long-wavelength regime. The extended Bruggeman homogenization formalism was employed to estimate the constitutive parameters of the HCM. In principle, the directions which support Voigt wave propagation in the HCM may be controlled by means of an applied dc electric field; and the degree of control may be sensitive to the porosity of the host material, the shapes, sizes and orientations of the pores, as well as the refractive index na. Here the theoretical methodology is presented; numerical results are presented elsewhere.
Designing homogenization-solution heat treatments for single crystal superalloys
International Nuclear Information System (INIS)
The conventional stepwise solutionizing method is studied for an experimental Ni-base single crystal superalloy using metallography, eutectic fraction analysis and electron microprobe analysis. The temperature range for solutionizing the alloy is determined by combinations of holding time and temperature. The effects of long isothermal holding within and above this solutioning temperature range are presented. Heat treatment steps below the γ'-solvus temperature stabilize the eutectic phase, while steps above the solvus temperature improve the homogenization and reduce eutectic phase fraction. There is a finite nucleation time for incipient melting which is a function of holding temperature above the equilibrium solidus of the alloy. A prolonged isothermal holding above the equilibrium solidus temperature causes up-hill diffusion at the eutectic region leading to incipient melting. A new homogenization-solution heat treatment approach with continuous heating between solvus and solidus is proposed.
Homogeneous thermal cloak with constant conductivity and tunable heat localization.
Han, Tiancheng; Yuan, Tao; Li, Baowen; Qiu, Cheng-Wei
2013-01-01
Invisible cloak has long captivated the popular conjecture and attracted intensive research in various communities of wave dynamics, e.g., optics, electromagnetics, acoustics, etc. However, their inhomogeneous and extreme parameters imposed by transformation-optic method will usually require challenging realization with metamaterials, resulting in narrow bandwidth, loss, polarization-dependence, etc. In this paper, we demonstrate that thermodynamic cloak can be achieved with homogeneous and finite conductivity only employing naturally available materials. It is demonstrated that the thermal localization inside the coating layer can be tuned and controlled robustly by anisotropy, which enables an incomplete cloak to function perfectly. Practical realization of such homogeneous thermal cloak has been suggested by using two naturally occurring conductive materials, which provides an unprecedentedly plausible way to flexibly realize thermal cloak and manipulate heat flow with phonons. PMID:23549139
Role of Clustering Coefficient on Cooperation Dynamics in Homogeneous Networks
Institute of Scientific and Technical Information of China (English)
WU Gang; GAO Kun; YANG Han-Xin; WANG Bing-Hong
2008-01-01
Based on previous works, we give further investigations on the Prisoners' Dilemma Game (PDG) on two different types of homogeneous networks, i.e. the homogeneous small-world network (HSWN) and the regular ring graph. We find that the so-called resonance-like character can occur on both the networks. Different from the viewpoint in previous publications, we think the small-world effect may be unnecessary to produce this character. Therefore, over these two types of networks, we suggest a common understanding in the viewpoint of clustering coefficient. Detailed simulation results can sustain our viewpoint quite well. Furthermore, we investigate the Snowdrift Game (SG) on the same networks. The difference between the outputs of the PDG and the SG can also sustain our viewpoint.
Microfluidic converging/diverging channels optimised for homogeneous extensional deformation.
Zografos, K; Pimenta, F; Alves, M A; Oliveira, M S N
2016-07-01
In this work, we optimise microfluidic converging/diverging geometries in order to produce constant strain-rates along the centreline of the flow, for performing studies under homogeneous extension. The design is examined for both two-dimensional and three-dimensional flows where the effects of aspect ratio and dimensionless contraction length are investigated. Initially, pressure driven flows of Newtonian fluids under creeping flow conditions are considered, which is a reasonable approximation in microfluidics, and the limits of the applicability of the design in terms of Reynolds numbers are investigated. The optimised geometry is then used for studying the flow of viscoelastic fluids and the practical limitations in terms of Weissenberg number are reported. Furthermore, the optimisation strategy is also applied for electro-osmotic driven flows, where the development of a plug-like velocity profile allows for a wider region of homogeneous extensional deformation in the flow field. PMID:27478523
Microfluidic converging/diverging channels optimised for homogeneous extensional deformation
Zografos, K.; Oliveira, M. S. N.
2016-01-01
In this work, we optimise microfluidic converging/diverging geometries in order to produce constant strain-rates along the centreline of the flow, for performing studies under homogeneous extension. The design is examined for both two-dimensional and three-dimensional flows where the effects of aspect ratio and dimensionless contraction length are investigated. Initially, pressure driven flows of Newtonian fluids under creeping flow conditions are considered, which is a reasonable approximation in microfluidics, and the limits of the applicability of the design in terms of Reynolds numbers are investigated. The optimised geometry is then used for studying the flow of viscoelastic fluids and the practical limitations in terms of Weissenberg number are reported. Furthermore, the optimisation strategy is also applied for electro-osmotic driven flows, where the development of a plug-like velocity profile allows for a wider region of homogeneous extensional deformation in the flow field.
Homogenization of some evolution problems in domains with small holes
Directory of Open Access Journals (Sweden)
Bituin Cabarrubias
2016-07-01
Full Text Available This article concerns the asymptotic behavior of the wave and heat equations in periodically perforated domains with small holes and Dirichlet conditions on the boundary of the holes. In the first part we extend to time-dependent functions the periodic unfolding method for domains with small holes introduced in [6]. Therein, the method was applied to the study of elliptic problems with oscillating coefficients in domains with small holes, recovering the homogenization result with a "strange term" originally obtained in [11] for the Laplacian. In the second part we obtain some homogenization results for the wave and heat equations with oscillating coefficients in domains with small holes. The results concerning the wave equation extend those obtained in [12] for the case where the elliptic part of the operator is the Laplacian.
Medical Informatics For Medical Students And Medical Practitioners
Directory of Open Access Journals (Sweden)
Jai MOHAN
2010-06-01
Full Text Available The importance of incorporating medical (or healthinformatics into the education of medical students andmedical practitioners is being increasingly recognised.The advances in information and communicationtechnology and the pervasion of the Internet intoeveryday life have important implications forhealthcare services and medical education.Students and practitioners should learn to utilisebiomedical information for problem solving anddecision making based on evidence. The extensiveintroduction of electronic health information systemsinto hospitals and clinics and at the enterprise level inMalaysia and elsewhere is driving a demand for healthprofessionals who have at least basic skills in andappreciation of the use of these technologies.The essential clinical informatics skills have beenidentified and should be incorporated into theundergraduate medical curriculum. It is recommendedthat these be introduced in stages and integrated intoexisting programmes rather than taught as a separatemodule. At the same time, medical schools shouldsupport the integration of e-learning in the educationalprocess in view of the numerous potential benefits.
Lyoluminescence of luminol in aqueous ammonia
International Nuclear Information System (INIS)
The emission spectrum of lyoluminescence of luminol in aqueous ammonia was recorded on a Fuess spectrograph. A continuous emission band from 370 to 600 nm, on resolution, showed three-banded emission with peaks at 413, 463 and 545 nm. The resolved fluorescence spectrum of luminol in ammonia showed two peaks, at 407 and 446 nm. The fluorescence lifetime of luminol in aqueous ammonia solution is 0.7 ns. The lyoluminescence emission bands are explained on the basis of the reactions of colour centres with luminol during the dissolution of irradiated NaCl crystals in an aqueous ammoniated solution of luminol. (author)
Ray, J.; Lee, B.; Baltrusaitis, J.; Jun, Y.
2012-12-01
Homogeneous and heterogeneous iron hydroxide nanoparticle nucleation can occur continuously in both natural and complex aqueous systems. Iron oxide nanoparticles can act as sinks and/or carriers for heavy metal contaminants; therefore, it is important to develop a better understanding of factors affecting their formation. Organic coatings are ubiquitous in aqueous environments where they can exist on mineral surfaces (e.g., biofilm), as nanoparticle surface coatings (e.g., natural organic matter), or be introduced as coagulants in water treatment systems. These surface coatings could influence the formation of iron oxide nanoparticles and thus, the mobility of aqueous contaminants. Therefore, to better understand the fate and transport of contaminants in complex aqueous environments, we need more accurate information about mechanisms governing heterogeneous and homogeneous nucleation and growth of iron(III) hydroxide nanoparticles in the presence of organic surface coatings. In this work, we used a unique measurement technique allowing for simultaneous small-angle X-ray scattering (SAXS) and grazing incidence (GISAXS) analysis to monitor nanoparticle nucleation in solution and at substrate surfaces. Clean quartz, and polyaspartate- and alginate-coated substrates were chosen as model substrates to represent mineral coatings, engineered organic coatings and natural organic coatings. Polyaspartate was determined to be the most negatively charged substrate and quartz to be the least negatively charged substrate; however, after 2 h of reaction, the total nanoparticle volume calculations—determined from GISAXS—indicate that precipitation of positively-charged iron(III) hydroxide nanoparticles is 10 times higher on the quartz substrate than on the polyaspartate substrate. This implies that electrostatics do not govern iron(III) hydroxide nucleation. Furthermore, homogeneous nucleation approximately 250 μm above the substrate surface was highest in the presence of the
Solving the Homogeneous Boltzmann Equation with Arbitrary Scattering Kernel
Hohenegger, A.
2008-01-01
With applications in astroparticle physics in mind, we generalize a method for the solution of the nonlinear, space homogeneous Boltzmann equation with isotropic distribution function to arbitrary matrix elements. The method is based on the expansion of the matrix element in terms of two cosines of the "scattering angles". The scattering functions used by previous authors in particle physics for matrix elements in Fermi-approximation are retrieved as lowest order results in this expansion. Th...
Nickel N-heterocyclic carbene complexes in homogeneous catalysis
Berding, Joris
2009-01-01
Described in this thesis are the investigations into the chemistry of N-heterocyclic carbene (NHC) ligands and transition-metal complexes thereof. Specifically, a variety of N-heterocyclic carbene complexes of nickel were prepared, characterized and used as catalysts in three types of homogeneous catalytic processes. First, nickel(II) complexes of monodentate NHC ligands were successfully used as catalysts in the hydrosilylation of internal alkynes. Second, nickel(II) complexes bearing bident...
Dynamic Model of the Price Dispersion of Homogeneous Goods
Kaldasch, Joachim
2015-01-01
Presented is an analytic microeconomic model of the temporal price dispersion of homogeneous goods in polypoly markets. This new approach is based on the idea that the price dispersion has its origin in the dynamics of the purchase process. The price dispersion is determined by the chance that demanded and supplied product units meet in a given price interval. It can be characterized by a fat-tailed Laplace distribution for short and by a lognormal distribution for long time horiz...
Stochastic homogenization of fully nonlinear uniformly elliptic equations revisited
Armstrong, Scott N.; Smart, Charles K.
2012-01-01
We give a simplified presentation of the obstacle problem approach to stochastic homogenization for elliptic equations in nondivergence form. Our argument also applies to equations which depend on the gradient of the unknown function. In the latter case, we overcome difficulties caused by a lack of estimates for the first derivatives of approximate correctors by modifying the perturbed test function argument to take advantage of the spreading of the contact set.
Creation of Tunable Homogeneous Thermal Cloak with Constant Conductivity
Han, Tiancheng; Li, Baowen; Qiu, Cheng-Wei
2013-01-01
Invisible cloak has long captivated the popular conjecture and attracted intensive research in various communities of wave dynamics, e.g., optics, electromagnetics, acoustics, etc. However, their inhomogeneous and extreme parameters imposed by transformation-optic method will usually require challenging realization with metamaterials, resulting in narrow bandwidth, loss, polarization-dependence, etc. On the contrary, we demonstrate that tunable thermodynamic cloak can be achieved with homogen...
Homogeneous Thermal Cloak with Constant Conductivity and Tunable Heat Localization
Han, Tiancheng; Yuan, Tao; Li, Baowen; Qiu, Cheng-Wei
2013-01-01
Invisible cloak has long captivated the popular conjecture and attracted intensive research in various communities of wave dynamics, e.g., optics, electromagnetics, acoustics, etc. However, their inhomogeneous and extreme parameters imposed by transformation-optic method will usually require challenging realization with metamaterials, resulting in narrow bandwidth, loss, polarization-dependence, etc. In this paper, we demonstrate that thermodynamic cloak can be achieved with homogeneous and f...
Homogenization of soil properties map by Principal Component Analysis
Valverde Arias, Omar; Garrido, Alberto; Villeta, Maria; Tarquis, Ana Maria
2016-04-01
It is widely known that extreme climatic phenomena occur with more intensity and frequency. This fact has put more pressure over farming, becoming very important to implement agriculture risk management policies by governments and institutions. One of the main strategies is transfer risk by agriculture insurance. Agriculture insurance based in indexes has gained importance in the last decade. And consist in a comparison between measured index values with a defined threshold that triggers damage losses. However, based index insurance could not be based on an isolated measurement. It is necessary to be integrated in a complete monitoring system that uses many sources of information and tools. For example, index influence areas, crop production risk maps, crop yields, claim statistics, and so on. To establish index influence area is necessary to have a secondary information that show us homogeneous climatic and soil areas, which inside of each homogeneous classes, index measurements on crops of interest are going to be similar, and in this way reduce basis risk. But it is necessary an efficient method to accomplish this aim, to get homogeneous areas that not depends on only in expert criteria and that could be widely used, for this reason this study asses two conventional agricultural and geographic methods (control and climatic maps) based in expert criteria, and one classical statistical method of multi-factorial analysis (factorial map), all of them to homogenize soil and climatic characteristics. Resulting maps were validated by agricultural and spatial analysis, obtaining very good results in statistical method (Factorial map) that proves to be an efficient and accuracy method that could be used for similar porpoises.
Numerical Integration of the Transport Equation For Infinite Homogeneous Media
International Nuclear Information System (INIS)
The transport equation for neutrons in infinite homogeneous media is solved by direct numerical integration. Accounts are taken to the anisotropy and the inelastic scattering. The integration has been performed by means of the trapezoidal rule and the length of the energy intervals are constant in lethargy scale. The machine used is a Ferranti Mercury computer. Results are given for water, heavy water, aluminium water mixture and iron-aluminium-water mixture
Some Questions Arising from the Homogeneous Banach Space Problem
Casazza, Peter G.
1992-01-01
We review the current state of the homogeneous Banach space problem. We then formulate several questions which arise naturally from this problem, some of which seem to be fundamental but new. We give many examples defining the bounds on the problem. We end with a simple construction showing that every infinite dimensional Banach space contains a subspace on which weak properties have become stable (under passing to further subspaces). Implications of this construction are considered.
On the transition between heterogeneous and homogeneous freezing
Directory of Open Access Journals (Sweden)
K. Gierens
2003-01-01
Full Text Available Box model simulations of an uplifting and adiabatically cooling cloud of aerosol have been performed in order to study the transition between cirrus formation dominated by homogeneous nucleation of ice to that dominated by heterogeneous nucleation. The aerosol was assumed to consist of an internal mixture of sulfuric acid solution droplets with inclusions of soot. The parametrisation of De Mott et al. (1997 was used to simulate the heterogeneous nucleation of ice in such droplets with soot inclusions. The simulations show that the transition from heterogeneous to homogeneous nucleation occurs over a narrow range of soot concentration. Thus it seems to be possible to fix critical concentrations of heterogeneous ice nuclei which must be exceeded if heterogeneous freezing dominates cirrus formation. A formula has been derived that allows to compute the critical concentrations of heterogeneous ice nuclei as a function of temperature, updraft speed, ambient pressure, and supersaturation at which heterogeneous freezing occurs. Generally, homogeneous nucleation dominates in regions with updrafts stronger than 20 cm s -1, with the exception of heavily polluted areas which could be common in the northern hemisphere due to air traffic, where updrafts of the order 1 m s-1 may be necessary to render heterogeneous nucleation unimportant. According to the present results it cannot be excluded that heterogeneous nucleation plays a more important role for cirrus formation in the northern midlatitudes than anywhere else. A possible consequence of these results is that air pollution may lead to a higher coverage of cirrus clouds, but then these clouds will be optically thinner than clouds formed by homogeneous freezing, with the exception of regions where condensation trails are frequent.
Cournot Oligopoly, Homogeneous Products and Grappa Market: An Econometric Study
2015-01-01
In this study, using scanner data, collected from super-market transactions in 2009, we estimate an eight equations simultaneous model with a 3SLS routine, with the objective to empirically analyze the Grappa market structure. Results show that the supply side of the Grappa market is characterized by an oligopolistic structure, where the dominant firms compete as oligopolists à la Cournot with homogeneous products. Firms’ competition is mostly played on the quantity grounds and mostly disrega...
Advanced homogenization strategies in material modeling of thermally sprayed TBCs
International Nuclear Information System (INIS)
Thermal barrier coatings (TBC), obtained by atmospheric plasma spraying (APS), have a complex microstructure (lamellar, porous, micro-cracked). Process parameters take an influence on this microstructure. Two methods based on the homogenization for periodic structures are presented in this article. The methods are used to calculate the effective material behavior of APS-TBCs made of partially yttria stabilized zirconia (PYSZ) depending on the microstructure. (Abstract Copyright [2006], Wiley Periodicals, Inc.)
Biased representation of homothetic preferences on homogeneous sets
Le Menestrel, Marc; LEMAIRE, Bertrand
2004-01-01
In the homogeneous case of one-dimensional objects, we show that any preference relation that is positive and homothetic can be represented by a quantitative utility function and unique bias. This bias may favor or disfavor the preference for an object. In the first case, preferences are complete but not transitive and an object may be preferred even when its utility is lower. In the second case, preferences are asymmetric and transitive but not negatively transitive and it may not be suffici...
Heterogenous skills and homogeneous land: segmentation and agglomeration
Wrede, Matthias
2009-01-01
This paper analyzes the impact of skill heterogeneity on regional patterns of production and housing in the presence of pecuniary externalities within a general equilibrium framework assuming monopolistic competition at intermediate good markets. It shows that the interplay of heterogenous skills and relatively homogeneous land demand triggers skill segmentation and agglomeration. The core region, being more attractive to high skilled workers, has a disproportionately large share of productio...
Heterogeneous Skills and Homogeneous Land: Segmentation and Agglomeration
Wrede, Matthias
2010-01-01
This paper analyzes the impact of skill heterogeneity on regional patterns of production and housing in the presence of pecuniary externalities within a general-equilibrium framework assuming monopolistic competition at intermediate good markets. It shows that the interplay of heterogeneous skills and relatively homogeneous land demand triggers skill segmentation and agglomeration. The core region, being more attractive to high skilled workers, has a disproportionately large share of producti...
EPR spectroscopy as a tool in homogeneous catalysis research
Goswami, M.; Chirila, A.; Rebreyend, C.; Bruin,, Henk
2015-01-01
In the context of homogeneous catalysis, open-shell systems are often quite challenging to characterize. Nuclear magnetic resonance (NMR) spectroscopy is the most frequently applied tool to characterize organometallic compounds, but NMR spectra are usually broad, difficult to interpret and often futile for the study of paramagnetic compounds. As such, electron paramagnetic resonance (EPR) has proven itself as a useful spectroscopic technique to characterize paramagnetic complexes and reactive...
Evaluation of basic mitochondrial functions using rat tissue homogenates
Czech Academy of Sciences Publication Activity Database
Pecinová, Alena; Drahota, Zdeněk; Nůsková, Hana; Pecina, Petr; Houštěk, Josef
2011-01-01
Roč. 11, č. 5 (2011), s. 722-728. ISSN 1567-7249 R&D Projects: GA MZd(CZ) NS9759; GA ČR(CZ) GAP303/11/0970; GA MŠk(CZ) 1M0520; GA MŠk OC08017 Institutional research plan: CEZ:AV0Z50110509 Keywords : oxidative phosphorylation * isolated mitochondria * tissue homogenates * respiratory control * membrane potential Subject RIV: FB - Endocrinology, Diabetology, Metabolism, Nutrition Impact factor: 3.615, year: 2011
Upscaling in vertically fractured oil reservoirs using homogenization
Salimi, H.; Bruining, H.
2009-01-01
Flow modeling in fractured reservoirs is largely confined to the so-called sugar cube model. Here, however, we consider vertically fractured reservoirs, i.e., the situation that the reservoir geometry can be approximated by fractures enclosed columns running from the base rock to the cap rock (aggregated columns). This article deals with the application of the homogenization method to derive an upscaled equation for fractured reservoirs with aggregated columns. It turns out that vertical flow...