The Substitution Effect on Reaction Enthalpies of Antioxidant Mechanisms of Juglone and Its Derivatives in Gas and Solution Phase: DFT Study

Directory of Open Access Journals (Sweden)

Aymard Didier Tamafo Fouegue

2018-01-01

Full Text Available We examined the structure-reaction enthalpies-antioxidant activity relationship of the molecule library built around juglone and its derivatives at B3LYP/6-31+G(d,p level. Three major antioxidant mechanisms (hydrogen atom transfer (HAT, single electron transfer-proton transfer (SET-PT, and sequential proton loss electron transfer (SPLET have been investigated in five solvents and in the gas phase. The delocalization of the unpaired electrons in the radicals or cation radicals has been explored by the natural bond orbital analysis and the interpretation of spin density maps. The results obtained have proven that the HAT mechanism is the thermodynamically preferred mechanism in the gas phase. But, in the solution phase, the SPLET mechanism has been shown to be more predominant than HAT. The reactivity order of compounds towards selected reactive oxygen species has also been studied.

Solutions without phase-slip for the Ginsburg-Landau equation

International Nuclear Information System (INIS)

Collet, P.; Eckmann, J.P.

1992-01-01

We consider the Ginsburg-Landau equation for a complex scalar field in one dimension and consider initial data which have two different stationary solutions as their limits in space as x→±∞. If these solutions are not very different, then we show that the initial data will evolve to a stationary solution by a 'phase melting' process which avoids 'phase slips,' i.e., which does not go through zero amplitude. (orig.)

Application of mechanical alloying to synthesis of intermetallic phases based alloys

International Nuclear Information System (INIS)

Dymek, S.

2001-01-01

Mechanical alloying is the process of synthesis of powder materials during milling in high energetic mills, usually ball mills. The central event in mechanical alloying is the ball-powder-ball collision. Powder particles are trapped between the colliding balls during milling and undergo deformation and/or fracture. Fractured parts are cold welded. The continued fracture and cold welding results in a uniform size and chemical composition of powder particles. The main applications of mechanical alloying are: processing of ODS alloys, syntheses of intermetallic phases, synthesis of nonequilibrium structures (amorphous alloys, extended solid solutions, nanocrystalline, quasi crystals) and magnetic materials. The present paper deals with application of mechanical alloying to synthesis Ni A l base intermetallic phases as well as phases from the Nb-Al binary system. The alloy were processed from elemental powders. The course of milling was monitored by scanning electron microscopy and X-ray diffraction. After milling, the collected powders were sieved by 45 μm grid and hot pressed (Nb alloys and NiAl) or hot extruded (NiAl). The resulting material was fully dense and exhibited fine grain (< 1 μm) and uniform distribution of oxide dispersoid. The consolidated material was compression and creep tested. The mechanical properties of mechanically alloys were superior to properties of their cast counterparts both in the room and elevated temperatures. Higher strength of mechanically alloyed materials results from their fine grains and from the presence of dispersoid. At elevated temperatures, the Nb-Al alloys have higher compression strength than NiAl-based alloys processed at the same conditions. The minimum creep rates of mechanically alloyed Nb alloys are an order of magnitude lower than analogously processed NiAl-base alloys. (author)

Mass transfer processes and field-scale transport of organic solutes

International Nuclear Information System (INIS)

Brusseau, M.L.

1990-01-01

The influence of mass transfer processes, such as sorption/desorption and mass transfer between immiscible liquids and water, on the transport of organic solutes is discussed. Rate-limited sorption of organic solutes caused by a diffusion-constrained mechanism is shown to be significant under laboratory conditions. The significance of the impact of nonequilibrium sorption on field-scale transport is scale dependent. The impact of organic liquids on mass transfer and transport of organic solutes depends upon the nature of the solute and the nature and form of the organic liquid. For example, while retardation of nonionic solutes is decreased in mixed-solvent systems, (i.e. systems comprised of water and a miscible organic liquid or an immiscible liquid present in concentrations below phase separation), the retardation of organic acids may, in some cases, increase with addition of a cosolvent. While the presence of an immiscible liquid existing as a mobile phase will reduce retention of organic solutes, the presence of residual saturation of an immiscible liquid can significantly increase retention. A model is presented that incorporates the effects of retention resulting from residual saturation, as well as nonequilibrium sorption, on the transport of organic solutes. (Author) (70 refs., 3 figs.)

Electronic structure tautomerism, and mechanism of H-D exchange in imidazole aqueous solutions

International Nuclear Information System (INIS)

Borisov, Yu.A.; Vorob'eva, N.P.; Abronin, I.A.; Kolomiets, A.F.

1988-01-01

The imidazole electronic structure in a gaseous phase is studied taking into account the influence of solvation effects in aqueous solutions. Possible mechanisms of tautomeric transformations and H-D exchange reactions with water molecules are discussed. Using the quantum chemistry methods, it is shown that the intramolecular mechanism of imidazole isomerization in the gaseous phase and the aqueous solution is unprofitable, and the intermolecular mechanism can proceed through the stage of protonated and carbene form formation

High dielectric permittivity and improved mechanical and thermal properties of poly(vinylidene fluoride) composites with low carbon nanotube content: effect of composite processing on phase behavior and dielectric properties.

Science.gov (United States)

Kumar, G Sudheer; Vishnupriya, D; Chary, K Suresh; Patro, T Umasankar

2016-09-23

The composite processing technique and nanofiller concentration and its functionalization significantly alter the properties of polymer nanocomposites. To realize this, multi-walled carbon nanotubes (CNT) were dispersed in a poly(vinylidene fluoride) (PVDF) matrix at carefully selected CNT concentrations by two illustrious methods, such as solution-cast and melt-mixing. Notwithstanding the processing method, CNTs induced predominantly the γ-phase in PVDF, instead of the commonly obtained β-phase upon nanofiller incorporation, and imparted significant improvements in dielectric properties. Acid-treatment of CNT improved its dispersion and interfacial adhesion significantly with PVDF, and induced a higher γ-phase content and better dielectric properties in PVDF as compared to pristine CNT. Further, the γ-phase content was found to be higher in solution-cast composites than that in melt-mixed counterparts, most likely due to solvent-induced crystallization in a controlled environment and slow solvent evaporation in the former case. However, interestingly, the melt-mixed composites showed a significantly higher dielectric constant at the onset of the CNT networked-structure as compared to the solution-cast composites. This suggests the possible role of CNT breakage during melt-mixing, which might lead to higher space-charge polarization at the polymer-CNT interface, and in turn an increased number of pseudo-microcapacitors in these composites than the solution-cast counterparts. Notably, PVDF with 0.13 vol% (volume fraction, f c  = 0.0013) of acid-treated CNTs, prepared by melt-mixing, displayed the relative permittivity of ∼217 and capacitance of ∼5430 pF, loss tangent of ∼0.4 at 1 kHz and an unprecedented figure of merit of ∼10(5). We suggest a simple hypothesis for the γ-phase formation and evolution of the high dielectric constant in these composites. Further, the high-dielectric composite film showed marked improvements in mechanical and thermal

Equilibrium and extraction mechanism from monomeric and polimeric species of zirconium in solution. part. 2

International Nuclear Information System (INIS)

Azevedo, H.L.P. de.

1980-01-01

The mechanism of extraction and the equilibrium of chemical species from Zirconium solutions was studied. The multiple extraction method was used to show the species envolved in the extraction process and qualitative informations was obtained about the equilibrium between extractable species (monomers) and non-extractable species (polymers) in the aqueous phase. (M.J.C.) [pt

Metastable Phase Separation and Concomitant Solute Redistribution of Liquid Fe-Cu-Sn Ternary Alloy

International Nuclear Information System (INIS)

Xiao-Mei, Zhang; Wei-Li, Wang; Ying, Ruan; Bing-Bo, Wei

2010-01-01

Liquid Fe-Cu-Sn ternary alloys with lower Sn contents are usually assumed to display a peritectic-type solidification process under equilibrium condition. Here we show that liquid Fe 47.5 Cu 47.5 Sn 5 ternary alloy exhibits a metastable immiscibility gap in the undercooling range of 51–329 K (0.19T L ). Macroscopic phase separation occurs once undercooling exceeds 196 K and causes the formation of a floating Fe-rich zone and a descending Cu-rich zone. Solute redistribution induces the depletion of Sn concentration in the Fe-rich zone and its enrichment in the Cu-rich zone. The primary Fe phase grows dendritically and its growth velocity increases with undercooling until the appearance of notable macrosegregation, but will decrease if undercooling further increases beyond 236 K. The microsegregation degrees of both solutes in Fe and Cu phases vary only slightly with undercooling. (condensed matter: structure, mechanical and thermal properties)

Hybrid vapor phase-solution phase growth techniques for improved CZT(S,Se) photovoltaic device performance

Energy Technology Data Exchange (ETDEWEB)

Chang, Liang-Yi; Gershon, Talia S.; Haight, Richard A.; Lee, Yun Seog

2016-12-27

A hybrid vapor phase-solution phase CZT(S,Se) growth technique is provided. In one aspect, a method of forming a kesterite absorber material on a substrate includes the steps of: depositing a layer of a first kesterite material on the substrate using a vapor phase deposition process, wherein the first kesterite material includes Cu, Zn, Sn, and at least one of S and Se; annealing the first kesterite material to crystallize the first kesterite material; and depositing a layer of a second kesterite material on a side of the first kesterite material opposite the substrate using a solution phase deposition process, wherein the second kesterite material includes Cu, Zn, Sn, and at least one of S and Se, wherein the first kesterite material and the second kesterite material form a multi-layer stack of the absorber material on the substrate. A photovoltaic device and method of formation thereof are also provided.

Fischer Indole Synthesis in the Gas Phase, the Solution Phase, and at the Electrospray Droplet Interface.

Science.gov (United States)

Bain, Ryan M; Ayrton, Stephen T; Cooks, R Graham

2017-07-01

Previous reports have shown that reactions occurring in the microdroplets formed during electrospray ionization can, under the right conditions, exhibit significantly greater rates than the corresponding bulk solution-phase reactions. The observed acceleration under electrospray ionization could result from a solution-phase, a gas-phase, or an interfacial reaction. This study shows that a gas-phase ion/molecule (or ion/ion) reaction is not responsible for the observed rate enhancement in the particular case of the Fischer indole synthesis. The results show that the accelerated reaction proceeds in the microdroplets, and evidence is provided that an interfacial process is involved. Graphical Abstract GRAPHICAL ABSTRACT TEXT HERE] -->.

Electrochemical processing of nitrate waste solutions. Phase 2, Final report

Energy Technology Data Exchange (ETDEWEB)

Genders, D.; Weinberg, N.; Hartsough, D. [Electrosynthesis Co., Inc., Cheektowaga, NY (US)

1992-10-07

The second phase of research performed at The Electrosynthesis Co., Inc. has demonstrated the successful removal of nitrite and nitrate from a synthetic effluent stream via a direct electrochemical reduction at a cathode. It was shown that direct reduction occurs at good current efficiencies in 1,000 hour studies. The membrane separation process is not readily achievable for the removal of nitrites and nitrates due to poor current efficiencies and membrane stability problems. A direct reduction process was studied at various cathode materials in a flow cell using the complete synthetic mix. Lead was found to be the cathode material of choice, displaying good current efficiencies and stability in short and long term tests under conditions of high temperature and high current density. Several anode materials were studied in both undivided and divided cell configurations. A divided cell configuration was preferable because it would prevent re-oxidation of nitrite by the anode. The technical objective of eliminating electrode fouling and solids formation was achieved although anode materials which had demonstrated good stability in short term divided cell tests corroded in 1,000 hour experiments. The cause for corrosion is thought to be F{sup {minus}} ions from the synthetic mix migrating across the cation exchange membrane and forming HF in the acid anolyte. Other possibilities for anode materials were explored. A membrane separation process was investigated which employs an anion and cation exchange membrane to remove nitrite and nitrate, recovering caustic and nitric acid. Present research has shown poor current efficiencies for nitrite and nitrate transport across the anion exchange membrane due to co-migration of hydroxide anions. Precipitates form within the anion exchange membranes which would eventually result in the failure of the membranes. Electrochemical processing offers a highly promising and viable method for the treatment of nitrate waste solutions.

Giant asymmetry of separation and homogenization processes in solid 3He-4He solutions

International Nuclear Information System (INIS)

Grigor'ev, V.N.; Majdanov, V.A.; Penzev, A.A.; Polev, A.V.; Rubets, S.P.; Rudavskij, Eh.Ya.; Rybalko, A.S.; Syrnikov, E.V.

2005-01-01

The kinetics of the processes of separation and homogenization of solid 3 He- 4 He solutions is compared by using the precision barometry. The experiments were made with the initial specimens of three types: weak 3 He- 4 He and 4 He- 3 He solutions and concentrated 3 He- 4 He ones. It is found that the homogenization rate at the initial stage may be more than 500 times higher that the rate of separation. This is the case for all types of the solutions studied. The appreciable rate of phase separation in the concentrated solutions where, according to the modern concepts, impurity atoms in quantum crystals should be localized, suggests that in such conditions there is a new unknown mechanism of mass-transfer, while the fast homogenization points to a nondiffusion nature of the process

Investigation of Processes Controlling Elution of Solutes from Nonaqueous Phase Liquid (NAPL) Pools into Groundwater

Science.gov (United States)

Seyedabbasi, M.; Pirestani, K.; Holland, S. B.; Imhoff, P. T.

2005-12-01

Two major processes influencing the elution of solutes from porous media contaminated with nonaqueous phase liquids (NAPLs) are external mass transfer between the NAPL and groundwater and internal diffusion through NAPL ganglia and pools. There is a relatively large body of literature on the dissolution of single-species NAPLs. Less is known about the rates of elution of compounds dissolving from multicomponent NAPLs. We examined the mass transfer of one solute, 2,3-dimethyl-2-butanol (DMB) - a partitioning tracer, between groundwater and a dense NAPL - trichloroethylene (TCE). Diffusion cell experiments were used to measure the molecular diffusion coefficient of DMB in pure TCE and in porous media contaminated with a TCE pool. Measured diffusion coefficients were compared with empirical correlations (pure TCE) and a parallel resistance model (TCE pool). Based on the results from these analyses, a dimensionless Biot number was derived to express the ratio of the external rate of mass transfer from a NAPL pool to the internal rate of diffusion within the pool, which varies with NAPL saturation and NAPL-water partition coefficient. Biot numbers were then estimated for several laboratory scale experiments involving DMB transport between NAPL pools and groundwater. The estimated Biot numbers were in good agreement with experimental results. The expression for the Biot number developed here may be used to assess the processes controlling the elution of solutes from NAPL pools, which has implications on long-term predictions of solute dissolution from NAPLs in the field.

MECHANICAL CHARACTERISTICS OF THREE-PHASE INDUCTION MOTORS WITH SINGLE-PHASE POWER SUPPLY

Directory of Open Access Journals (Sweden)

V.S. Malyar

2016-06-01

Full Text Available Aim. Development of a method for calculating mechanical characteristics of three-phase induction motors with single-phase power supply. Methods. The developed algorithm is based on the high-adequacy mathematical model of motor and projection method for solving the boundary problem for equations of electrical circuits balance presented in the three-phase coordinate system. As a result of asymmetry of power supply to the stator windings, in steady state, flux-linkage and current change according to the periodic law. They are determined by solving the boundary problem. Results. The developed mathematical model allows determining periodic dependence of coordinates as a function of slip and, based on them, mechanical characteristics of motors. Academic novelty. The developed method relies on a completely new mathematical approach to calculation of stationary modes of nonlinear electromagnetic circuits, which allows obtaining periodic solution in a timeless domain. Practical value. Using the developed calculation algorithm, one can select capacitance required to start an induction motor with single-phase power supply and calculate static mechanical characteristics at a given capacitance.

Solution-processed copper-nickel nanowire anodes for organic solar cells

Science.gov (United States)

Stewart, Ian E.; Rathmell, Aaron R.; Yan, Liang; Ye, Shengrong; Flowers, Patrick F.; You, Wei; Wiley, Benjamin J.

2014-05-01

This work describes a process to make anodes for organic solar cells from copper-nickel nanowires with solution-phase processing. Copper nanowire films were coated from solution onto glass and made conductive by dipping them in acetic acid. Acetic acid removes the passivating oxide from the surface of copper nanowires, thereby reducing the contact resistance between nanowires to nearly the same extent as hydrogen annealing. Films of copper nanowires were made as oxidation resistant as silver nanowires under dry and humid conditions by dipping them in an electroless nickel plating solution. Organic solar cells utilizing these completely solution-processed copper-nickel nanowire films exhibited efficiencies of 4.9%.This work describes a process to make anodes for organic solar cells from copper-nickel nanowires with solution-phase processing. Copper nanowire films were coated from solution onto glass and made conductive by dipping them in acetic acid. Acetic acid removes the passivating oxide from the surface of copper nanowires, thereby reducing the contact resistance between nanowires to nearly the same extent as hydrogen annealing. Films of copper nanowires were made as oxidation resistant as silver nanowires under dry and humid conditions by dipping them in an electroless nickel plating solution. Organic solar cells utilizing these completely solution-processed copper-nickel nanowire films exhibited efficiencies of 4.9%. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01024h

Pitfall in quantum mechanical/molecular mechanical molecular dynamics simulation of small solutes in solution.

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Hu, Hao; Liu, Haiyan

2013-05-30

Developments in computing hardware and algorithms have made direct molecular dynamics simulation with the combined quantum mechanical/molecular mechanical methods affordable for small solute molecules in solution, in which much improved accuracy can be obtained via the quantum mechanical treatment of the solute molecule and even sometimes water molecules in the first solvation shell. However, unlike the conventional molecular mechanical simulations of large molecules, e.g., proteins, in solutions, special care must be taken in the technical details of the simulation, including the thermostat of the solute/solvent system, so that the conformational space of the solute molecules can be properly sampled. We show here that the common setup for classical molecular mechanical molecular dynamics simulations, such as the Berendsen or single Nose-Hoover thermostat, and/or rigid water models could lead to pathological sampling of the solutes' conformation. In the extreme example of a methanol molecule in aqueous solution, improper and sluggish setups could generate two peaks in the distribution of the O-H bond length. We discuss the factors responsible for this somewhat unexpected result and evoke a simple and ancient technical fix-up to resolve this problem.

The growth and tensile deformation behavior of the silver solid solution phase with zinc

International Nuclear Information System (INIS)

Wu, Jiaqi; Lee, Chin C.

2016-01-01

The growth of homogeneous silver solid solution phase with zinc are conducted at two different compositions. X-ray diffraction (XRD) and Scanning electron microscope/Energy dispersive X-ray spectroscopy (SEM/EDX) are carried out for phase identification and chemical composition verification. The mechanical properties of silver solid solution phase with zinc are evaluated by tensile test. The engineering and true stress vs. strain curves are presented and analyzed, with those of pure silver in comparison. According to the experimental results, silver solid solution phase with zinc at both compositions show tempered yield strength, high tensile strength and large uniform strain compared to those of pure silver. Fractography further confirmed the superior ductility of silver solid solution phase with zinc at both compositions. Our preliminary but encouraging results may pave the way for the silver based alloys to be applied in industries such as electronic packaging and structure engineering.

The feasibility of using solution-processed aqueous La2O3 as effective hole injection layer in organic light-emitting diode

Science.gov (United States)

Zhang, Yan; Li, Wanshu; Zhang, Ting; Yang, Bo; Zheng, Qinghong; Xu, Jiwen; Wang, Hua; Wang, Lihui; Zhang, Xiaowen; Wei, Bin

2018-01-01

Low-cost and scalable manufacturing boosts organic electronic devices with all solution process. La2O3 powders and corresponding aqueous solutions are facilely synthesized. Atomic force microscopy and scanning electron microscopy measurements show that solution-processed La2O3 behaves superior film morphology. X-ray diffraction and X-ray photoelectron spectroscopy measurements verify crystal phase and typical La signals. In comparison with the most widely-used hole injection layers (HILs) of MoOx and poly(ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), enhanced luminous efficiency is observed in organic light-emitting diode (OLED) using solution-processed La2O3 HIL. Current-voltage, impedance-voltage and phase angle-voltage transition curves clarify that solution-processed La2O3 behaves nearly comparable hole injection capacity to MoOx and PEDOT:PSS, and favorably tailors carrier balance. Moreover, the hole injection mechanism of solution-processed La2O3 is proven to be predominantly controlled by Fowler-Nordheim tunneling process and the hole injection barrier height between ITO and NPB via La2O3 interlayer is estimated to be 0.098 eV. Our experiments provide a feasible application of La2O3 in organic electronic devices with solution process.

Energy and Resource Saving of Steelmaking Process: Utilization of Innovative Multi-phase Flux During Dephosphorization Process

Science.gov (United States)

Matsuura, Hiroyuki; Hamano, Tasuku; Zhong, Ming; Gao, Xu; Yang, Xiao; Tsukihashi, Fumitaka

2014-09-01

An increase in the utilization efficiency of CaO, one of the major fluxing agents used in various steelmaking processes, is required to reduce the amount of discharged slag and energy consumption of the process. The authors have intensively focused on the development of innovative dephosphorization process by using so called "multi-phase flux" composed of solid and liquid phases. This article summarizes the research on the above topic done by the authors, in which the formation mechanisms of P2O5-containing phase during CaO or 2CaO·SiO2 dissolution into molten slag, the phase relationship between solid and liquid phases at equilibrium, and thermodynamic properties of P2O5-containing phase have been clarified. The reactions between solid CaO or 2CaO·SiO2 and molten CaO-FeO x -SiO2-P2O5 slag were observed by dipping solid specimen in the synthesized slag at 1573 K or 1673 K. The formation of the CaO-FeO layer and dual-phase layer of solid 2CaO·SiO2 and FeO x -rich liquid phase was observed around the interface from the solid CaO side toward the bulk slag phase side. Condensation of P2O5 into 2CaO·SiO2 phase as 2CaO·SiO2-3CaO·P2O5 solid solution was observed in both cases of CaO and 2CaO·SiO2 as solid specimens. Measurement of the phase relationship for the CaO-FeO x -SiO2-P2O5 system confirmed the condensation of P2O5 in solid phase at low oxygen partial pressure. The thermodynamics of 2CaO·SiO2-3CaO·P2O5 solid solution are to be clarified to quantitatively simulate the dephosphorization process, and the current results are also introduced. Based on the above results, the reduction of CaO consumption, the discharged slag curtailment, and energy-saving effects have been discussed.

Phase Evolution and Mechanical Properties of AlCoCrFeNiSi x High-Entropy Alloys Synthesized by Mechanical Alloying and Spark Plasma Sintering

Science.gov (United States)

Kumar, Anil; Swarnakar, Akhilesh Kumar; Chopkar, Manoj

2018-05-01

In the current investigation, AlCoCrFeNiSi x (x = 0, 0.3, 0.6 and 0.9 in atomic ratio) high-entropy alloy systems are prepared by mechanical alloying and subsequently consolidated by spark plasma sintering. The microstructural and mechanical properties were analyzed to understand the effect of Si addition in AlCoCrFeNi alloy. The x-ray diffraction analysis reveals the supersaturated solid solution of the body-centered cubic structure after 20 h of ball milling. However, the consolidation promotes the transformation of body-centered phases partially into the face-centered cubic structure and sigma phases. A recently proposed geometric model based on the atomic stress theory has been extended for the first time to classify single phase and multi-phases on the high-entropy alloys prepared by mechanical alloying and spark plasma sintering process. Improved microhardness and better wear resistance were achieved as the Si content increased from 0 to 0.9 in the present high-entropy alloy.

Ultrathin SnO2 nanorods: template- and surfactant-free solution phase synthesis, growth mechanism, optical, gas-sensing, and surface adsorption properties.

Science.gov (United States)

Xi, Guangcheng; Ye, Jinhua

2010-03-01

A novel template- and surfactant-free low temperature solution-phase method has been successfully developed for the controlled synthesis of ultrathin SnO(2) single-crystalline nanorods for the first time. The ultrathin SnO(2) single-crystalline nanorods are 2.0 +/- 0.5 nm in diameter, which is smaller than its exciton Bohr radius. The ultrathin SnO(2) nanorods show a high specific area (191.5 m(2) g(-1)). Such a thin SnO(2) single-crystalline nanorod is new in the family of SnO(2) nanostrucures and presents a strong quantum confinement effect. Its formation depends on the reaction temperature as well as on the concentration of the urea solution. A nonclassical crystallization process, Ostwald ripening process followed by an oriented attachment mechanism, is proposed based on the detailed observations from a time-dependent crystal evolution process. Importantly, such structured SnO(2) has shown a strong structure-induced enhancement of gas-sensing properties and has exhibited greatly enhanced gas-sensing property for the detection of ethanol than that of other structured SnO(2), such as the powders of nanobelts and microrods. Moreover, these ultrathin SnO(2) nanorods exhibit excellent ability to remove organic pollutant in wastewater by enormous surface adsorption. These properties are mainly attributed to its higher surface-to-volume ratio and ultrathin diameter. This work provides a novel low temperature, green, and inexpensive pathway to the synthesis of ultrathin nanorods, offering a new material form for sensors, solar cells, catalysts, water treatments, and other applications.

Phase evolution during early stages of mechanical alloying of Cu–13 wt.% Al powder mixtures in a high-energy ball mill

International Nuclear Information System (INIS)

Dudina, Dina V.; Lomovsky, Oleg I.; Valeev, Konstantin R.; Tikhov, Serguey F.; Boldyreva, Natalya N.; Salanov, Aleksey N.; Cherepanova, Svetlana V.; Zaikovskii, Vladimir I.; Andreev, Andrey S.; Lapina, Olga B.; Sadykov, Vladislav A.

2015-01-01

Highlights: • Phase formation during early stages of Cu–Al mechanical alloying was studied. • The products of mechanical alloying are of highly non-equilibrium character. • X-ray amorphous phases are present in the products of mechanical alloying. • An Al-rich X-ray amorphous phase is distributed between the crystallites. - Abstract: We report the phase and microstructure evolution of the Cu–13 wt.% Al mixture during treatment in a high-energy planetary ball mill with a particular focus on the early stages of mechanical alloying. Several characterization techniques, including X-ray diffraction phase analysis, nuclear magnetic resonance spectroscopy, differential dissolution, thermal analysis, and electron microscopy/elemental analysis, have been combined to study the evolution of the phase composition of the mechanically alloyed powders and describe the microstructure of the multi-phase products of mechanical alloying at different length scales. The following reaction sequence has been confirmed: Cu + Al → CuAl 2 (+Cu) → Cu 9 Al 4 + (Cu) → Cu(Al). The phase evolution was accompanied by the microstructure changes, the layered structure of the powder agglomerates disappearing with milling time. This scheme is further complicated by the processes of copper oxidation, reduction of copper oxides by metallic aluminum, and by variation of the stoichiometry of Cu(Al) solid solutions with milling time. Substantial amounts of X-ray amorphous phases were detected as well. Differential dissolution technique has revealed that a high content of aluminum in the Cu(Al) solid solution-based powders is due to the presence of Al-rich phases distributed between the Cu(Al) crystallites

Synthesis of TiO2 Nanoparticles from Ilmenite Through the Mechanism of Vapor-Phase Reaction Process by Thermal Plasma Technology

Science.gov (United States)

Samal, Sneha

2017-11-01

Synthesis of nanoparticles of TiO2 was carried out by non-transferred arc thermal plasma reactor using ilmenite as the precursor material. The powder ilmenite was vaporized at high temperature in plasma flame and converted to a gaseous state of ions in the metastable phase. On cooling, chamber condensation process takes place on recombination of ions for the formation of nanoparticles. The top-to-bottom approach induces the disintegration of complex ilmenite phases into simpler compounds of iron oxide and titanium dioxide phases. The vapor-phase reaction mechanism was carried out in thermal plasma zone for the synthesis of nanoparticles from ilmenite compound in a plasma reactor. The easy separation of iron particles from TiO2 was taken place in the plasma chamber with deposition of light TiO2 particles at the top of the cooling chamber and iron particles at the bottom. The dissociation and combination process of mechanism and synthesis are studied briefly in this article. The product TiO2 nanoparticle shows the purity with a major phase of rutile content. TiO2 nanoparticles produced in vapor-phase reaction process shows more photo-induced capacity.

Direct NMR Monitoring of Phase Separation Behavior of Highly Supersaturated Nifedipine Solution Stabilized with Hypromellose Derivatives.

Science.gov (United States)

Ueda, Keisuke; Higashi, Kenjirou; Moribe, Kunikazu

2017-07-03

We investigated the phase separation behavior and maintenance mechanism of the supersaturated state of poorly water-soluble nifedipine (NIF) in hypromellose (HPMC) derivative solutions. Highly supersaturated NIF formed NIF-rich nanodroplets through phase separation from aqueous solution containing HPMC derivative. Dissolvable NIF concentration in the bulk water phase was limited by the phase separation of NIF from the aqueous solution. HPMC derivatives stabilized the NIF-rich nanodroplets and maintained the NIF supersaturation with phase-separated NIF for several hours. The size of the NIF-rich phase was different depending on the HPMC derivatives dissolved in aqueous solution, although the droplet size had no correlation with the time for which NIF supersaturation was maintained without NIF crystallization. HPMC acetate and HPMC acetate succinate (HPMC-AS) effectively maintained the NIF supersaturation containing phase-separated NIF compared with HPMC. Furthermore, HPMC-AS stabilized NIF supersaturation more effectively in acidic conditions. Solution 1 H NMR measurements of NIF-supersaturated solution revealed that HPMC derivatives distributed into the NIF-rich phase during the phase separation of NIF from the aqueous solution. The hydrophobicity of HPMC derivative strongly affected its distribution into the NIF-rich phase. Moreover, the distribution of HPMC-AS into the NIF-rich phase was promoted at lower pH due to the lower aqueous solubility of HPMC-AS. The distribution of a large amount of HPMC derivatives into NIF-rich phase induced the strong inhibition of NIF crystallization from the NIF-rich phase. Polymer distribution into the drug-rich phase directly monitored by solution NMR technique can be a useful index for the stabilization efficiency of drug-supersaturated solution containing a drug-rich phase.

Intermolecular interactions in the condensed phase: Evaluation of semi-empirical quantum mechanical methods.

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Christensen, Anders S; Kromann, Jimmy C; Jensen, Jan H; Cui, Qiang

2017-10-28

To facilitate further development of approximate quantum mechanical methods for condensed phase applications, we present a new benchmark dataset of intermolecular interaction energies in the solution phase for a set of 15 dimers, each containing one charged monomer. The reference interaction energy in solution is computed via a thermodynamic cycle that integrates dimer binding energy in the gas phase at the coupled cluster level and solute-solvent interaction with density functional theory; the estimated uncertainty of such calculated interaction energy is ±1.5 kcal/mol. The dataset is used to benchmark the performance of a set of semi-empirical quantum mechanical (SQM) methods that include DFTB3-D3, DFTB3/CPE-D3, OM2-D3, PM6-D3, PM6-D3H+, and PM7 as well as the HF-3c method. We find that while all tested SQM methods tend to underestimate binding energies in the gas phase with a root-mean-squared error (RMSE) of 2-5 kcal/mol, they overestimate binding energies in the solution phase with an RMSE of 3-4 kcal/mol, with the exception of DFTB3/CPE-D3 and OM2-D3, for which the systematic deviation is less pronounced. In addition, we find that HF-3c systematically overestimates binding energies in both gas and solution phases. As most approximate QM methods are parametrized and evaluated using data measured or calculated in the gas phase, the dataset represents an important first step toward calibrating QM based methods for application in the condensed phase where polarization and exchange repulsion need to be treated in a balanced fashion.

Intermolecular interactions in the condensed phase: Evaluation of semi-empirical quantum mechanical methods

Science.gov (United States)

Christensen, Anders S.; Kromann, Jimmy C.; Jensen, Jan H.; Cui, Qiang

2017-10-01

To facilitate further development of approximate quantum mechanical methods for condensed phase applications, we present a new benchmark dataset of intermolecular interaction energies in the solution phase for a set of 15 dimers, each containing one charged monomer. The reference interaction energy in solution is computed via a thermodynamic cycle that integrates dimer binding energy in the gas phase at the coupled cluster level and solute-solvent interaction with density functional theory; the estimated uncertainty of such calculated interaction energy is ±1.5 kcal/mol. The dataset is used to benchmark the performance of a set of semi-empirical quantum mechanical (SQM) methods that include DFTB3-D3, DFTB3/CPE-D3, OM2-D3, PM6-D3, PM6-D3H+, and PM7 as well as the HF-3c method. We find that while all tested SQM methods tend to underestimate binding energies in the gas phase with a root-mean-squared error (RMSE) of 2-5 kcal/mol, they overestimate binding energies in the solution phase with an RMSE of 3-4 kcal/mol, with the exception of DFTB3/CPE-D3 and OM2-D3, for which the systematic deviation is less pronounced. In addition, we find that HF-3c systematically overestimates binding energies in both gas and solution phases. As most approximate QM methods are parametrized and evaluated using data measured or calculated in the gas phase, the dataset represents an important first step toward calibrating QM based methods for application in the condensed phase where polarization and exchange repulsion need to be treated in a balanced fashion.

Retention prediction of highly polar ionizable solutes under gradient conditions on a mixed-mode reversed-phase and weak anion-exchange stationary phase.

Science.gov (United States)

Balkatzopoulou, P; Fasoula, S; Gika, H; Nikitas, P; Pappa-Louisi, A

2015-05-29

In the present work the retention of three highly polar and ionizable solutes - uric acid, nicotinic acid and ascorbic acid - was investigated on a mixed-mode reversed-phase and weak anion-exchange (RP/WAX) stationary phase in buffered aqueous acetonitrile (ACN) mobile phases. A U-shaped retention behavior was observed for all solutes with respect to the eluent organic modifier content studied in a range of 5-95% (v/v). This retention behavior clearly demonstrates the presence of a HILIC-type retention mechanism at ACN-rich hydro-organic eluents and an RP-like retention at aqueous-rich hydro-organic eluents. Hence, this column should be promising for application under both RP and HILIC gradient elution modes. For this reason, a series of programmed elution runs were carried out with increasing (RP) and decreasing (HILIC) organic solvent concentration in the mobile phase. This dual gradient process was successfully modeled by two retention models exhibiting a quadratic or a cubic dependence of the logarithm of the solute retention factor (lnk) upon the organic modifier volume fraction (φ). It was found that both models produced by gradient retention data allow the prediction of solute retention times for both types of programmed elution on the mixed-mode column. Four, in the case of the quadratic model, or five, in the case of the cubic model, initial HILIC- and RP-type gradient runs gave satisfactory retention predictions of any similar kind elution program, even with different flow rate, with an overall error of only 2.5 or 1.7%, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

Surface phase transitions in cu-based solid solutions

Science.gov (United States)

Zhevnenko, S. N.; Chernyshikhin, S. V.

2017-11-01

We have measured surface energy in two-component Cu-based systems in H2 + Ar gas atmosphere. The experiments on solid Cu [Ag] and Cu [Co] solutions show presence of phase transitions on the surfaces. Isotherms of the surface energy have singularities (the minimum in the case of copper solid solutions with silver and the maximum in the case of solid solutions with cobalt). In both cases, the surface phase transitions cause deficiency of surface miscibility: formation of a monolayer (multilayer) (Cu-Ag) or of nanoscale particles (Cu-Co). At the same time, according to the volume phase diagrams, the concentration and temperature of the surface phase transitions correspond to the solid solution within the volume. The method permits determining the rate of diffusional creep in addition to the surface energy. The temperature and concentration dependence of the solid solutions' viscosity coefficient supports the fact of the surface phase transitions and provides insights into the diffusion properties of the transforming surfaces.

Kinetics of physico-chemical processes during intensive mechanical processing of ZnO-MnO2 powder mixture

International Nuclear Information System (INIS)

Kakazey, M.; Vlasova, M.; Dominguez-Patino, M.; Juarez-Arellano, E.A.; Bykov, A.; Leon, I.; Siqueiros-Diaz, A.

2011-01-01

Experimental results of electron paramagnetic resonance spectra, X-ray diffraction, scanning electron microscopy and infrared spectroscopy demonstrate that the kinetic of the physical and chemical processes that takes place during prolonged intensive mechanical processing (MP, 0 MP >3120min) of powder mixtures of 50%wt ZnO+50%wt MnO 2 can be described as a three stage process. (1) 0 MP >30min, particles destruction, formation of superficial defects, fast increment of sample average temperature (from 290 to ∼600K) and annealing of defects with the lowest energy of activation E ac . (2) 30 MP >390min, further particle destruction, slow increment of sample average temperature (from ∼600 to ∼700K), formation and growth of a very disordered layer of β-MnO 2 around ZnO particles, dehydration of MnO 2 , formation of solid solution of Mn 2+ ions in ZnO, formation of nano-quasiamorphous states in the ZnO-MnO 2 mixture and onset of the formation of the ZnMnO 3 phase. (3) 390 MP >3120min, the sample average temperature remains constant (∼700K), the reaction is completed and the spinel ZnMnO 3 phase with a unit cell a=8.431(1) A and space group Fd3-barm is the only phase present in the sample. No ferromagnetism at room temperature was detected in this study. - Highlights: → The kinetics during mechanical processing of ZnO-MnO 2 samples is a three stage process. → First stage, reduction of crystallites size and accumulation of defects. → Second stage, nano-quasiamorphous states formation and onset of the ZnMnO 3 phase. → Third stage, complete reaction to the spinel ZnMnO 3 phase.

Phase transformation and microstructural changes during ageing process of an Ag-Pd-Cu-Au alloy

Energy Technology Data Exchange (ETDEWEB)

Yu, Chin-Ho; Park, Mi-Gyoung; Kwon, Yong Hoon; Seol, Hyo-Joung [Department of Dental Materials, School of Dentistry and Medical Research Institute, Pusan National University, 1-10 Ami-dong, Seo-gu, Pusan 602-739 (Korea, Republic of); Kim, Hyung-Il [Department of Dental Materials, School of Dentistry and Medical Research Institute, Pusan National University, 1-10 Ami-dong, Seo-gu, Pusan 602-739 (Korea, Republic of)], E-mail: hilkim@pusan.ac.kr

2008-07-28

Age-hardening behaviour and the related phase transformation and microstructural changes during isothermal ageing process were studied to elucidate the age-hardening mechanism of an Ag-based dental casting alloy composed of Ag-Pd-Cu-Au-Zn, Ir and In by means of hardness test, X-ray diffraction (XRD), scanning electron microscopic (SEM) observations and energy dispersive spectroscopic microanalysis (EDS). In the hardness test at 350 and 400 deg. C, the hardness of the solution-treated specimen began to increase and reached a maximum value with increasing ageing time, and subsequently the hardness decreased gradually. By considering XRD results and SEM observations together, the solution-treated specimen consisted of three phases, the Ag-rich {alpha}{sub 1} phase as a matrix, the Cu-Pd {alpha}{sub 2} phase and the CuPd {beta} phase with a CsCl-type as particle-like structures. By ageing the solution-treated specimen, the Ag-rich {alpha}{sub 1} and Cu-Pd {alpha}{sub 2} phases were transformed into the Ag-rich {alpha}{sup '}{sub 1} and Cu{sub 3}Pd {alpha}{sup '}{sub 2} phases, respectively. The CuPd {beta} phase with a CsCl-type was not changed apparently during the ageing process. From the results of the hardness test, XRD study, SEM observations and EDS analysis, it could be derived that the hardness increased by the diffusion and precipitation of the Cu-rich phase from the Ag-rich matrix during the early stage of phase transformation of {alpha}{sub 1} into {alpha}{sup '}{sub 1} and that the progress of coarsening of the Cu-rich precipitates with an entanglement structure caused the hardness decrease during the later stage of phase transformation of {alpha}{sub 1} into {alpha}{sup '}{sub 1}. The particle-like structures composed of the Cu-Pd {alpha}{sub 2} and the CuPd {beta} phase with a CsCl-type contributed little to the hardness increase which occurred in the early stage of aging process.

Molecular thermodynamics using fluctuation solution theory

DEFF Research Database (Denmark)

Ellegaard, Martin Dela

. The framework relates thermodynamic variables to molecular pair correlation functions of liquid mixtures. In this thesis, application of the framework is illustrated using two approaches: 1. Solubilities of solid solutes in mixed solvent systems are determined from fluctuation solution theory application......Properties of chemicals and their mutual phase equilibria are critical variables in process design. Reliable estimates of relevant equilibrium properties, from thermodynamic models, can form the basis of good decision making in the development phase of a process design, especially when access...... to relevant experimental data is limited. This thesis addresses the issue of generating and using simple thermodynamic models within a rigorous statistical mechanical framework, the so-called fluctuation solution theory, from which relations connecting properties and phase equilibria can be obtained...

A novel solution-phase route for the synthesis of crystalline silver nanowires

International Nuclear Information System (INIS)

Liu Yang; Chu Ying; Yang Likun; Han Dongxue; Lue Zhongxian

2005-01-01

A unique solution-phase route was devised to synthesize crystal Ag nanowires with high aspect-ratio (8-10 nm in diameter and length up to 10 μm) by the reduction of AgNO 3 with Vitamin C in SDS/ethanol solution. The resultant nanoproducts were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD) and electron diffraction (ED). A soft template mechanism was put forward to interpret the formation of metal Ag nanowires

Effects of solution treatment on mechanical properties and corrosion resistance of 4A duplex stainless steel

Energy Technology Data Exchange (ETDEWEB)

Lu, Panpan; Wang, Aiqin; Wang, Wenyan [Henan Univ. of Science and Technology, Luoyang (China). School of Material Science and Engineering; Xie, Jingpei [Henan Univ. of Science and Technology, Luoyang (China). Collaborative Innovation Center of Nonferrous Metals

2018-02-15

In this study, 4A duplex stainless steels were prepared via remelting in an intermediate frequency furnace and subsequently solution treated at different temperatures. The effects of solution treatment on the mechanical properties and corrosion resistance of 4A duplex stainless steel were investigated. Microstructures were characterized via optical microscopy and scanning electron microscopy. The mechanical properties were evaluated via hardness test, tensile test, and impact test experiments. The point corrosion resistance was studied via chemical immersion and potentiodynamic anodic polarization. The results showed that with increasing solution temperature in the range of 1223 - 1423 K, the tensile strength and hardness first decreased and then increased, and minimum values were obtained at 1323 K. The σ phase precipitated at the boundaries of the α/γ phases in samples solution treated at 1223 K, decreasing both impact energy and pitting potential of the experimental steels. When experimental steels were solution treated at 1373 K for 2 h, a suitable volume fraction of α/γ was uniformly distributed throughout the microstructure, and the steels exhibited optimal mechanical properties and pitting corrosion resistance.

Thermogravimetric analysis of phase transitions in cement compositions mixed by sodium silicate solution

Directory of Open Access Journals (Sweden)

Fedosov Sergey Viktorovich

2014-01-01

Full Text Available This paper presents a study of the capability to modify cement by mechanical activation of sodium silicate water solution. Admixtures or blends of binding agents were employed for modifying concrete properties. The liquid glass is applied to protect from chemically or physically unfavorable environmental impacts, such as acidic medium and high temperature. The sodium silicate is a high-capacity setting accelerator. The increasing of the liquid glass proportion in the mix leads to the degradation of the cement paste plasticity and for this reason it is necessary to reduce the amount of liquid glass in the cement paste. The activation of dilute water solution of sodium silicate into rotary pulsating apparatus directly before tempering of the cement paste is an effective way to decrease mass fraction of liquid glass in the cement paste. The results of the combined influence of liquid glass and mechanical activation on physicochemical processes taking place in cement stone are represented in this research. Thermogravimetric analysis was used in order to study cement blends. Thermogravimetric analysis of modified cement stone assays was performed by thermo analyzer SETARAM TGA 92-24. The results of the analysis of phase transition taking place under high-temperature heating of cement stone modified by the mechanical activation of the water solution of the sodium silicate were introduced. Thermograms of cement stone assays were obtained at different hardening age. The comparison of these thermograms allows us to come to a conclusion on the formation and the retention during long time of a more dense structure of the composite matrix mixed by the mechanical activation of sodium silicate water solution. The relation between the concrete composition and its strength properties was stated. Perhaps, the capability of modified concrete to keep calcium ions in sparingly soluble hydrosilicates leads to the increase in its durability and corrosion resistance.

All-solution-processed flexible thin film piezoelectric nanogenerator

Energy Technology Data Exchange (ETDEWEB)

Chung, Sung Yun; Kim, Sunyoung; Kim, Kyongjun [Program in Nano Science and Technology, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 151-744 (Korea, Republic of); Lee, Ju-Hyuck; Kim, Sang-Woo [SKKU Advanced Institute of Nanotechnology, School of Advanced Materials Science and Engineering, Sungkyunkwan University (SKKU), Suwon 440-746 (Korea, Republic of); Kang, Chong-Yun; Yoon, Seok-Jin [Electronic Materials Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Kim, Youn Sang [Program in Nano Science and Technology, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 151-744 (Korea, Republic of); Advanced Institutes of Convergence Technology, 864-1 Iui-dong, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-270 (Korea, Republic of)

2012-11-27

An all-solution-processed flexible thin film piezoelectric nanogenerator is demonstrated using reactive zinc hydroxo-condensation and a screen-printing method. The highly elastic thin film allows the piezoelectric energy to be generated through the mechanical rolling and muscle stretching of the piezoelectric unit. This flexible all solution-processed nanogenerator is promising for use in future energy harvesters such as wearable human patches and mobile electronics. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Multi-level quantum mechanics theories and molecular mechanics study of the double-inversion mechanism of the F- + CH3I reaction in aqueous solution.

Science.gov (United States)

Liu, Peng; Zhang, Jingxue; Wang, Dunyou

2017-06-07

A double-inversion mechanism of the F - + CH 3 I reaction was discovered in aqueous solution using combined multi-level quantum mechanics theories and molecular mechanics. The stationary points along the reaction path show very different structures to the ones in the gas phase due to the interactions between the solvent and solute, especially strong hydrogen bonds. An intermediate complex, a minimum on the potential of mean force, was found to serve as a connecting-link between the abstraction-induced inversion transition state and the Walden-inversion transition state. The potentials of mean force were calculated with both the DFT/MM and CCSD(T)/MM levels of theory. Our calculated free energy barrier of the abstraction-induced inversion is 69.5 kcal mol -1 at the CCSD(T)/MM level of theory, which agrees with the one at 72.9 kcal mol -1 calculated using the Born solvation model and gas-phase data; and our calculated free energy barrier of the Walden inversion is 24.2 kcal mol -1 , which agrees very well with the experimental value at 25.2 kcal mol -1 in aqueous solution. The calculations show that the aqueous solution makes significant contributions to the potentials of mean force and exerts a big impact on the molecular-level evolution along the reaction pathway.

Solution processing of chalcogenide materials using thiol-amine "alkahest" solvent systems.

Science.gov (United States)

McCarthy, Carrie L; Brutchey, Richard L

2017-05-02

Macroelectronics is a major focus in electronics research and is driven by large area applications such as flat panel displays and thin film solar cells. Innovations for these technologies, such as flexible substrates and mass production, will require efficient and affordable semiconductor processing. Low-temperature solution processing offers mild deposition methods, inexpensive processing equipment, and the possibility of high-throughput processing. In recent years, the discovery that binary "alkahest" mixtures of ethylenediamine and short chain thiols possess the ability to dissolve bulk inorganic materials to yield molecular inks has lead to the wide study of such systems and the straightforward recovery of phase pure crystalline chalcogenide thin films upon solution processing and mild annealing of the inks. In this review, we recount the work that has been done toward elucidating the scope of this method for the solution processing of inorganic materials for use in applications such as photovoltaic devices, electrocatalysts, photodetectors, thermoelectrics, and nanocrystal ligand exchange. We also take stock of the wide range of bulk materials that can be used as soluble precursors, and discuss the work that has been done to reveal the nature of the dissolved species. This method has provided a vast toolbox of over 65 bulk precursors, which can be utilized to develop new routes to functional chalcogenide materials. Future studies in this area should work toward a better understanding of the mechanisms involved in the dissolution and recovery of bulk materials, as well as broadening the scope of soluble precursors and recoverable functional materials for innovative applications.

An adaptive quantum mechanics/molecular mechanics method for the infrared spectrum of water: incorporation of the quantum effect between solute and solvent.

Science.gov (United States)

Watanabe, Hiroshi C; Banno, Misa; Sakurai, Minoru

2016-03-14

Quantum effects in solute-solvent interactions, such as the many-body effect and the dipole-induced dipole, are known to be critical factors influencing the infrared spectra of species in the liquid phase. For accurate spectrum evaluation, the surrounding solvent molecules, in addition to the solute of interest, should be treated using a quantum mechanical method. However, conventional quantum mechanics/molecular mechanics (QM/MM) methods cannot handle free QM solvent molecules during molecular dynamics (MD) simulation because of the diffusion problem. To deal with this problem, we have previously proposed an adaptive QM/MM "size-consistent multipartitioning (SCMP) method". In the present study, as the first application of the SCMP method, we demonstrate the reproduction of the infrared spectrum of liquid-phase water, and evaluate the quantum effect in comparison with conventional QM/MM simulations.

Kinetics of physico-chemical processes during intensive mechanical processing of ZnO-MnO{sub 2} powder mixture

Energy Technology Data Exchange (ETDEWEB)

Kakazey, M.; Vlasova, M.; Dominguez-Patino, M. [CIICAp-Universidad Autonoma del Estado de Morelos, Cuernavaca (Mexico); Juarez-Arellano, E.A., E-mail: eajuarez@unpa.edu.mx [Universidad del Papaloapan, Tuxtepec, Oaxaca (Mexico); Bykov, A. [Institute for Problems of Materials Science of NASU, Kyiv (Ukraine); Leon, I. [CIQ-Universidad Autonoma del Estado de Morelos, Cuernavaca (Mexico); Siqueiros-Diaz, A. [FCQI-Universidad Autonoma del Estado de Morelos, Cuernavaca (Mexico)

2011-10-15

Experimental results of electron paramagnetic resonance spectra, X-ray diffraction, scanning electron microscopy and infrared spectroscopy demonstrate that the kinetic of the physical and chemical processes that takes place during prolonged intensive mechanical processing (MP, 03120min) of powder mixtures of 50%wt ZnO+50%wt MnO{sub 2} can be described as a three stage process. (1) 030min, particles destruction, formation of superficial defects, fast increment of sample average temperature (from 290 to {approx}600K) and annealing of defects with the lowest energy of activation E{sub ac}. (2) 30390min, further particle destruction, slow increment of sample average temperature (from {approx}600 to {approx}700K), formation and growth of a very disordered layer of {beta}-MnO{sub 2} around ZnO particles, dehydration of MnO{sub 2}, formation of solid solution of Mn{sup 2+} ions in ZnO, formation of nano-quasiamorphous states in the ZnO-MnO{sub 2} mixture and onset of the formation of the ZnMnO{sub 3} phase. (3) 3903120min, the sample average temperature remains constant ({approx}700K), the reaction is completed and the spinel ZnMnO{sub 3} phase with a unit cell a=8.431(1) A and space group Fd3-barm is the only phase present in the sample. No ferromagnetism at room temperature was detected in this study. - Highlights: > The kinetics during mechanical processing of ZnO-MnO{sub 2} samples is a three stage process. > First stage, reduction of crystallites size and accumulation of defects. > Second stage, nano-quasiamorphous states formation and onset of the ZnMnO{sub 3} phase. > Third stage, complete reaction to the spinel ZnMnO{sub 3} phase.

The immiscible aqueous solutions of alkyl phosphates. Study for the purpose of uranium extraction from phosphoric acid solutions

International Nuclear Information System (INIS)

Mauborgne, Bernard

1979-01-01

Systems of immiscible aqueous solutions composed by a phase rich in mineral salt and by another phase almost totally containing an organic salt, have been studied for years, with quaternary ammonium salts with an organic cation. The objective of this research is to study systems symmetric to the previous ones, i.e. with organic anions such as alkyl phosphates, and then to try to understand mechanisms of extraction of metals in these environments. Based on properties of immiscible aqueous solutions, an original three-phase process of liquid-liquid extraction has been developed, and is used to separate uranium in phosphoric acids with better performance than the existing industrial processes [fr

Network periodic solutions: patterns of phase-shift synchrony

International Nuclear Information System (INIS)

Golubitsky, Martin; Wang, Yunjiao; Romano, David

2012-01-01

We prove the rigid phase conjecture of Stewart and Parker. It then follows from previous results (of Stewart and Parker and our own) that rigid phase-shifts in periodic solutions on a transitive network are produced by a cyclic symmetry on a quotient network. More precisely, let X(t) = (x 1 (t), ..., x n (t)) be a hyperbolic T-periodic solution of an admissible system on an n-node network. Two nodes c and d are phase-related if there exists a phase-shift θ cd in [0, 1) such that x d (t) = x c (t + θ cd T). The conjecture states that if phase relations persist under all small admissible perturbations (that is, the phase relations are rigid), then for each pair of phase-related cells, their input signals are also phase-related to the same phase-shift. For a transitive network, rigid phase relations can also be described abstractly as a Z m permutation symmetry of a quotient network. We discuss how patterns of phase-shift synchrony lead to rigid synchrony, rigid phase synchrony, and rigid multirhythms, and we show that for each phase pattern there exists an admissible system with a periodic solution with that phase pattern. Finally, we generalize the results to nontransitive networks where we show that the symmetry that generates rigid phase-shifts occurs on an extension of a quotient network

Monte Carlo Solutions for Blind Phase Noise Estimation

Directory of Open Access Journals (Sweden)

Çırpan Hakan

2009-01-01

Full Text Available This paper investigates the use of Monte Carlo sampling methods for phase noise estimation on additive white Gaussian noise (AWGN channels. The main contributions of the paper are (i the development of a Monte Carlo framework for phase noise estimation, with special attention to sequential importance sampling and Rao-Blackwellization, (ii the interpretation of existing Monte Carlo solutions within this generic framework, and (iii the derivation of a novel phase noise estimator. Contrary to the ad hoc phase noise estimators that have been proposed in the past, the estimators considered in this paper are derived from solid probabilistic and performance-determining arguments. Computer simulations demonstrate that, on one hand, the Monte Carlo phase noise estimators outperform the existing estimators and, on the other hand, our newly proposed solution exhibits a lower complexity than the existing Monte Carlo solutions.

Formation of U(IV) Nanoparticles and Their Growth Mechanism in Mildly Acidic Aqueous Phases

Energy Technology Data Exchange (ETDEWEB)

Cha, Wan Sik; Kim, Sun Tae; Cho, Hye Ryun; Jung, Euo Chang [KAERI, Daejeon (Korea, Republic of)

2016-05-15

Previous studies suggest that U(IV) nanoparticle (NP) formation is one of key steps in mineralization or immobilization of uranium which can be mediated either by microbes or by abiotic geochemical reactions. Colloidal NPs in a groundwater system are potential carrier phases influencing RN migration in subsurface environment. However, the mechanism of U(IV) NP formation and the potential reaction intermediates during this solid phase formation process have not been elucidated in detail so far. In this study we attempted to examine the U(IV) nanoparticle formation reactions preceded by the hydrolysis of U{sup 4+} at different pHs, concentrations and temperatures. The kinetics of U(IV) NP formation from dissolved U(IV) species was monitored under mildly acidic conditions (pH 2 ∼ 3) mainly by using UV-Vis absorption spectrophotometry. Dynamic light scattering (DLS) analysis, nanoparticle tracking analysis (NTA) and transmission electron microscopy (TEM) were used to characterize the NPs produced during the reactions. The results demonstrate that the U(IV) NP formation process is very sensitive toward temperature variation. The main outcome of this study is the discovery of the autocatalytic nature of U(IV) NP formation from the supersaturated U(OH){sup 3+} solution in a mildly acidic aqueous solution. The structure of reaction intermediates is proposed to contain oxide linkage. In the presentation the proposed mechanism of the U(IV) NP formation reaction and the properties of primary NPs and their clusters will be discussed in detail.

Phase coexistence in ferroelectric solid solutions: Formation of monoclinic phase with enhanced piezoelectricity

Directory of Open Access Journals (Sweden)

Xiaoyan Lu

2016-10-01

Full Text Available Phase morphology and corresponding piezoelectricity in ferroelectric solid solutions were studied by using a phenomenological theory with the consideration of phase coexistence. Results have shown that phases with similar energy potentials can coexist, thus induce interfacial stresses which lead to the formation of adaptive monoclinic phases. A new tetragonal-like monoclinic to rhombohedral-like monoclinic phase transition was predicted in a shear stress state. Enhanced piezoelectricity can be achieved by manipulating the stress state close to a critical stress field. Phase coexistence is universal in ferroelectric solid solutions and may provide a way to optimize ultra-fine structures and proper stress states to achieve ultrahigh piezoelectricity.

Development of Three-Layer Simulation Model for Freezing Process of Food Solution Systems

Science.gov (United States)

Kaminishi, Koji; Araki, Tetsuya; Shirakashi, Ryo; Ueno, Shigeaki; Sagara, Yasuyuki

A numerical model has been developed for simulating freezing phenomena of food solution systems. The cell model was simplified to apply to food solution systems, incorporating with the existence of 3 parts such as unfrozen, frozen and moving boundary layers. Moreover, the moving rate of freezing front model was also introduced and calculated by using the variable space network method proposed by Murray and Landis (1957). To demonstrate the validity of the model, it was applied to the freezing processes of coffee solutions. Since the model required the phase diagram of the material to be frozen, the initial freezing temperatures of 1-55 % coffee solutions were measured by the DSC method. The effective thermal conductivity for coffee solutions was determined as a function of temperature and solute concentration by using the Maxwell - Eucken model. One-dimensional freezing process of 10 % coffee solution was simulated based on its phase diagram and thermo-physical properties. The results were good agreement with the experimental data and then showed that the model could accurately describe the change in the location of the freezing front and the distributions of temperature as well as ice fraction during a freezing process.

Quantum mechanical force fields for condensed phase molecular simulations

Science.gov (United States)

Giese, Timothy J.; York, Darrin M.

2017-09-01

Molecular simulations are powerful tools for providing atomic-level details into complex chemical and physical processes that occur in the condensed phase. For strongly interacting systems where quantum many-body effects are known to play an important role, density-functional methods are often used to provide the model with the potential energy used to drive dynamics. These methods, however, suffer from two major drawbacks. First, they are often too computationally intensive to practically apply to large systems over long time scales, limiting their scope of application. Second, there remain challenges for these models to obtain the necessary level of accuracy for weak non-bonded interactions to obtain quantitative accuracy for a wide range of condensed phase properties. Quantum mechanical force fields (QMFFs) provide a potential solution to both of these limitations. In this review, we address recent advances in the development of QMFFs for condensed phase simulations. In particular, we examine the development of QMFF models using both approximate and ab initio density-functional models, the treatment of short-ranged non-bonded and long-ranged electrostatic interactions, and stability issues in molecular dynamics calculations. Example calculations are provided for crystalline systems, liquid water, and ionic liquids. We conclude with a perspective for emerging challenges and future research directions.

Process for disposal of aqueous solutions containing radioactive isotopes

Science.gov (United States)

Colombo, Peter; Neilson, Jr., Robert M.; Becker, Walter W.

1979-01-01

A process for disposing of radioactive aqueous waste solutions whereby the waste solution is utilized as the water of hydration to hydrate densified powdered portland cement in a leakproof container; said waste solution being dispersed without mechanical inter-mixing in situ in said bulk cement, thereafter the hydrated cement body is impregnated with a mixture of a monomer and polymerization catalyst to form polymer throughout the cement body. The entire process being carried out while maintaining the temperature of the components during the process at a temperature below 99.degree. C. The container containing the solid polymer-impregnated body is thereafter stored at a radioactive waste storage dump such as an underground storage dump.

Process for disposal of aqueous solutions containing radioactive isotopes

International Nuclear Information System (INIS)

Colombo, P.; Neilson, R.M. Jr.; Becker, W.W.

1979-01-01

A process for disposing of radioactive aqueous waste solutions whereby the waste solution is utilized as the water of hydration to hydrate densified powdered portland cement in a leakproof container; said waste solution being dispersed without mechanical inter-mixing in situ in said bulk cement, thereafter the hydrated cement body is impregnated with a mixture of a monomer and polymerization catalyst to form polymer throughout the cement body. The entire process being carried out while maintaining the temperature of the components during the process at a temperature below 99 0 C. The container containing the solid polymer-impregnated body is thereafter stored at a radioactive waste storage dump such as an underground storage dump

Design of the Precipitation Process for Ni-Al Alloys with Optimal Mechanical Properties: A Phase-Field Study

Science.gov (United States)

Ta, Na; Zhang, Lijun; Du, Yong

2014-04-01

An attempt to design the heat treatment schedule for binary Ni-Al alloys with optimal mechanical properties was made in the present work. A series of quantitative three-dimensional (3-D) phase-field simulations of microstructure evolution in Ni-Al alloys during the precipitation process were first performed using MICRESS (MICRostructure Evolution Simulation Software) package developed in the formalism of the multi-phase field model. The coupling to CALPHAD (CALculation of PHAse Diagram) thermodynamic and atomic mobility databases was realized via TQ interface. Moreover, the temperature-dependent lattice misfits and elastic constants were utilized for simulation. The effect of the alloy composition and aging temperature on microstructure evolution was extensively studied with the aid of statistical analysis. After that, an evaluation function was proposed for evaluating the optimal heat treatment schedule by choosing the phase fraction, grain size, and shape factor of γ' precipitate as the evaluation indicators. Based on 50 groups of phase-field-simulated and experimental microstructure information, as well as the proposed evaluation function, the optimal alloy composition, aging temperature, and aging time for binary Ni-Al alloy with optimal mechanical properties were finally chosen. The successful application in the present Ni-Al alloys indicates that it is possible to design the optimal alloy composition and heat treatment for other binary and even multicomponent alloys with optimal mechanical properties based on the evaluation function and the sufficient microstructure information. Additionally, the combination of the present method and the key experiments can definitely accelerate the material design and improve the efficiency and accuracy.

Studies on the retention mechanism of solutes in hydrophilic interaction chromatography using stoichiometric displacement theory I. The linear relationship of lgk' vs. lg[H2O].

Science.gov (United States)

Wang, Fei; Yang, Fan; Tian, Yang; Liu, Jiawei; Shen, Jiwei; Bai, Quan

2018-01-01

A stoichiometric displacement model for retention (SDM-R) of small solutes and proteins based on hydrophilic interaction chromatography (HILIC) was presented. A linear equation that related the logarithm of the capacity factor of the solute to the logarithm of the concentration of water in the mobile phase was derived. The stoichiometric displacement parameters, Z (the number of water molecules required to displace a solute from ligands) and lgI (containing a number of constants that relate to the affinity of solute to the ligands) could be obtained from the slope and the intercept of the linear plots of lgk' vs. lg[H 2 O]. The retention behaviors and retention mechanism of 15 kinds of small solutes and 6 kinds of proteins on 5 kinds HILIC columns with different ligands were investigated with SDM-R in typical range of water concentration in mobile phase. A good linear relationship between lgk' and lg[H 2 O] demonstrated that the most rational retention mechanism of solute in HILIC was a stoichiometric displacement process between solute and solvent molecules with water as displacing agents, which was not only valid for small solutes, but also could be used to explain the retention mechanism of biopolymers in HILIC. Comparing with the partition and adsorption models in HILIC, SDM-R was superior to them. Copyright © 2017 Elsevier B.V. All rights reserved.

A study on the mechanism of stress corrosion cracking of duplex stainless steels in hot alkaline-sulfide solution

Science.gov (United States)

Chasse, Kevin Robert

Duplex stainless steels (DSS) generally have superior strength and corrosion resistance as compared to most standard austenitic and ferritic stainless grades owing to a balanced microstructure of austenite and ferrite. As a result of having favorable properties, DSS have been selected for the construction of equipment in pulp and paper, chemical processing, nuclear, oil and gas as well as other industries. The use of DSS has been restricted in some cases because of stress corrosion cracking (SCC), which can initiate and grow in either the ferrite or austenite phase depending on the environment. Thorough understanding of SCC mechanisms of DSS in chloride- and hydrogen sulfide-containing solutions has been useful for material selection in many environments. However, understanding of SCC mechanisms of DSS in sulfide-containing caustic solutions is limited, which has restricted the capacity to optimize process and equipment design in pulp and paper environments. Process environments may contain different concentrations of hydroxide, sulfide, and chloride, altering corrosion and SCC susceptibility of each phase. Crack initiation and growth behavior will also change depending on the relative phase distribution and properties of austenite and ferrite. The role of microstructure and environment on the SCC of standard grade UNS S32205 and lean grade UNS S32101 in hot alkaline-sulfide solution were evaluated in this work using electrochemical, film characterization, mechanical testing, X-ray diffraction, and microscopy techniques. Microstructural aspects, which included residual stress state, phase distribution, phase ratio, and microhardness, were related to the propensity for SCC crack initiation in different simulated alkaline pulping liquors at 170 °C. Other grades of DSS and reference austenitic and superferritic grades of stainless steel were studied using exposure coupons for comparison to understand compositional effects and individual phase susceptibility

Application of optical processing to adaptive phased array radar

Science.gov (United States)

Carroll, C. W.; Vijaya Kumar, B. V. K.

1988-01-01

The results of the investigation of the applicability of optical processing to Adaptive Phased Array Radar (APAR) data processing will be summarized. Subjects that are covered include: (1) new iterative Fourier transform based technique to determine the array antenna weight vector such that the resulting antenna pattern has nulls at desired locations; (2) obtaining the solution of the optimal Wiener weight vector by both iterative and direct methods on two laboratory Optical Linear Algebra Processing (OLAP) systems; and (3) an investigation of the effects of errors present in OLAP systems on the solution vectors.

The mechanism of reequilibration of solids in the presence of a fluid phase

International Nuclear Information System (INIS)

Putnis, Andrew; Putnis, Christine V.

2007-01-01

The preservation of morphology (pseudomorphism) and crystal structure during the transformation of one solid phase to another is regularly used as a criterion for a solid-state mechanism, even when there is a fluid phase present. However, a coupled dissolution-reprecipitation mechanism also preserves the morphology and transfers crystallographic information from parent to product by epitaxial nucleation. The generation of porosity in the product phase is a necessary condition for such a mechanism as it allows fluid to maintain contact with a reaction interface which moves through the parent phase from the original surface. We propose that interface-coupled dissolution-reprecipitation is a general mechanism for reequilibration of solids in the presence of a fluid phase. - Graphical abstract: A single crystal of KBr is transformed to a porous single crystal of KCl by immersion in saturated KCl solution. The image shows partial transformation of a crystal of KBr (core) to KCl (porous, milky rim) by an interface coupled dissolution-reprecipitation mechanism. The external dimensions and crystallographic orientation of the original crystal are preserved, while a reaction interface moves through the crystal

Mechanism of nucleation and growth of hydrogen porosity in solidifying A356 aluminum alloy: an analytical solution

International Nuclear Information System (INIS)

Li, K.-D.; Chang, Edward

2004-01-01

This study derives an analytical solution for the mechanism of nucleation and growth of hydrogen pore in the solidifying A356 aluminum alloy. A model of initial transient hydrogen redistribution in the growing dendritic grain is used to modify the lever rule for the mechanism of nucleation of pore. The model predicts the fraction of solid at nucleation, the temperature range of nucleation, the radius of hydrogen diffusion cell, and the supersaturation of hydrogen needed for nucleation. The role of solidus velocity in nucleation is explained. The parameters calculated from the model of nucleation are used for analyzing the mechanism of kinetic diffusion-controlled growth of pore, in which the mathematical transformations of variables are introduced. With the transformations, it is argued that the diffusion problem involving the liquid and solid phases during solidification could be treated as a classic problem of precipitation in the single-phase medium treated by Ham or Avrami. The analytical solution for the nucleation of pore is compared with the mechanism of macrosegregation. The predicted volume percent of porosity and radius of pore based on the mechanism of growth of pore is discussed with respect to the thermodynamic solution, the published experimental data, the numerical solutions, and the role of interdendritic fluid flow governed by Darcy's law

Heterogeneous Ferroelectric Solid Solutions Phases and Domain States

CERN Document Server

Topolov, Vitaly

2012-01-01

The book deals with perovskite-type ferroelectric solid solutions for modern materials science and applications, solving problems of complicated heterophase/domain structures near the morphotropic phase boundary and applications to various systems with morphotropic phases. In this book domain state–interface diagrams are presented for the interpretation of heterophase states in perovskite-type ferroelectric solid solutions. It allows to describe the stress relief in the presence of polydomain phases, the behavior of unit-cell parameters of coexisting phases and the effect of external electric fields. The novelty of the book consists in (i) the first systematization of data about heterophase states and their evolution in ferroelectric solid solutions (ii) the general interpretation of heterophase and domain structures at changing temperature, composition or electric field (iii) the complete analysis of interconnection domain structures, unit-cell parameters changes, heterophase structures and stress relief.

Phase stability in wear-induced supersaturated Al-Ti solid solution

Energy Technology Data Exchange (ETDEWEB)

Watanabe, Y.; Yokoyama, K. [Dept. of Functional Machinery Mechanics Shinshu Univ., Ueda (Japan); Hosoda, H. [Precision and Intelligence Lab., Tokyo Inst. of Tech., Nagatsuta, Midori-ku, Yokohama (Japan)

2002-07-01

Al-Ti supersaturated solid solutions were introduced by wear testing and the rapid quenching of an Al/Al{sub 3}Ti composite (part of an Al/Al{sub 3}Ti functionally graded material) that was fabricated using the centrifugal method. The phase stability of the supersaturated solid solution was studied through systematic annealing of the supersaturated solid solution. It was found that the Al-Ti supersaturated solid solution decomposed into Al and Al{sub 3}Ti intermetallic compound phases during the heat treatment. The Al-Ti supersaturated solid solutions fabricated were, therefore, not an equilibrium phase, and thus decomposed into the equilibrium phases during heat treatment. It was also found that heat treatment leads to a significant hardness increase for the Al-Ti supersaturated solid solution. Finally, it was concluded that formation of the wear-induced supersaturated solid solution layer was a result of severe plastic deformation. (orig.)

Mechanisms of diffusional phase transformations in metals and alloys

CERN Document Server

Aaronson, Hubert I; Lee, Jong K

2010-01-01

Developed by the late metallurgy professor and master experimentalist Hubert I. Aaronson, this collection of lecture notes details the fundamental principles of phase transformations in metals and alloys upon which steel and other metals industries are based. Mechanisms of Diffusional Phase Transformations in Metals and Alloys is devoted to solid-solid phase transformations in which elementary atomic processes are diffusional jumps, and these processes occur in a series of so-called nucleation and growth through interface migration. Instead of relying strictly on a pedagogical approach, it doc

Heterogeneous nucleation promotes carrier transport in solution-processed organic field-effect transistors

KAUST Repository

Li, Ruipeng

2012-09-04

A new way to investigate and control the growth of solution-cast thin films is presented. The combination of in situ quartz crystal microbalance measurements with dissipation capabilities (QCM-D) and in situ grazing-incidence wide-angle X-ray scattering (GIWAXS) in an environmental chamber provides unique quantitative insights into the time-evolution of the concentration of the solution, the onset of nucleation, and the mode of growth of the organic semiconductor under varied drying conditions. It is demonstrated that careful control over the kinetics of solution drying enhances carrier transport significantly by promoting phase transformation predominantly via heterogeneous nucleation and sustained surface growth of a highly lamellar structure at the solid-liquid interface at the expense of homogeneous nucleation. A new way to investigate and control the growth of drop-cast thin films is presented. The solution-processing of small-molecule thin films of TIPS-pentacene is investigated using time-resolved techniques to reveal the mechanisms of nucleation and growth leading to solid film formation. By tuning the drying speed of the solution, the balance between surface and bulk growth modes is altered, thereby controlling the lamellar formation and tuning the carrier mobility in organic field-effect transistors Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

From quantum mechanics to finance: Microfoundations for jumps, spikes and high volatility phases in diffusion price processes

Science.gov (United States)

Henkel, Christof

2017-03-01

We present an agent behavior based microscopic model that induces jumps, spikes and high volatility phases in the price process of a traded asset. We transfer dynamics of thermally activated jumps of an unexcited/excited two state system discussed in the context of quantum mechanics to agent socio-economic behavior and provide microfoundations. After we link the endogenous agent behavior to price dynamics we establish the circumstances under which the dynamics converge to an Itô-diffusion price processes in the large market limit.

Effects of solution treatment on the microstructure and mechanical properties of Al-Cu-Mg-Ag alloy

International Nuclear Information System (INIS)

Liu, Xiao Yan; Pan, Qing Lin; Lu, Zhi Lun; Cao, Su Fang; He, Yun Bin; Li, Wen Bin

2010-01-01

The effects of solution treatment on the microstructure and mechanical properties of Al-Cu-Mg-Ag alloy were studied by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), differential scanning calorimeter (DSC), transmission electron microscopy (TEM) and tensile test, respectively. The results show that the mechanical property increases and then decreases with increasing the solution temperature. And the residual phases are dissolved into the matrix gradually, the number fraction of the precipitation and the size of recrystallized grains increase. Compared to the solution temperature, the solution holding time has less effect on the microstructure and the mechanical properties of Al-Cu-Mg-Ag alloy. The overburnt temperature of Al-Cu-Mg-Ag alloy is 525 o C. The yield strength and the elongation get the best when the alloy is solution treated at 515 o C for 1.5 h, is 504 MPa and 12.2% respectively. The fracture mechanism of the samples is ductile fracture.

Purification process for aqueous solutions of rare earths by liquid-liquid extraction

International Nuclear Information System (INIS)

Rollat, A.; Sabot, J.L.; Burgard, M.; Delloye, T.

1986-01-01

Alkaline earth metals are removed by liquid-liquid extraction between on aqueous nitric phase of impure rare earth compounds and an organic phase of polyether (crown ether). This process is particularly suited to removal of Ca, Ba and Ra contained in nitric solutions of rare earths [fr

High mobility solution-processed hybrid light emitting transistors

International Nuclear Information System (INIS)

Walker, Bright; Kim, Jin Young; Ullah, Mujeeb; Burn, Paul L.; Namdas, Ebinazar B.; Chae, Gil Jo; Cho, Shinuk; Seo, Jung Hwa

2014-01-01

We report the design, fabrication, and characterization of high-performance, solution-processed hybrid (inorganic-organic) light emitting transistors (HLETs). The devices employ a high-mobility, solution-processed cadmium sulfide layer as the switching and transport layer, with a conjugated polymer Super Yellow as an emissive material in non-planar source/drain transistor geometry. We demonstrate HLETs with electron mobilities of up to 19.5 cm 2 /V s, current on/off ratios of >10 7 , and external quantum efficiency of 10 −2 % at 2100 cd/m 2 . These combined optical and electrical performance exceed those reported to date for HLETs. Furthermore, we provide full analysis of charge injection, charge transport, and recombination mechanism of the HLETs. The high brightness coupled with a high on/off ratio and low-cost solution processing makes this type of hybrid device attractive from a manufacturing perspective

Process for removing a mixture containing iodine and alkyl iodine compounds from a gas phase or aqueous solution with ion-exchange resins

Energy Technology Data Exchange (ETDEWEB)

Shimizu, H; Mizuuchi, A; Yokoyama, F

1968-10-04

Iodine and alkyl iodine compounds are removed from a gas phase or aqueous solution containing salts, iodine and iodine compounds, such as the ambient gas in a reactor, if an accident should occur. The process comprises contacting the phase or solution: (a) with a hydrogen type strongly acidic cationic exchange resin, (b) with an anionic exchange resin containing quarternary ammonium and (c) with an anionic exchange resin containing free basic type tertiary amine, in this order or by reversing the order of the two anionic exchange resins. Although no problems arise in the liquid phase reaction, the ion-exchange resins in the gas phase reaction are desired in the moist state in order to stable maintain the migration speed of the materials to be removed regardless of the relative humidity of the amibent gas. In example I, Amberlite IRA-900 of 200 mm thickness as the lowermost bed, Amberlite IRA93 of 200 mm thickness as the middle bed and Amberlite 200 of 200 mm thickness as the uppermost bed were filled respectively, in a methacrylate resin cylinder with an inner diameter of 25 mm. A solution containing 15.9 mg/1 of iodine, 41.2 mg/1 of methyl iodide and 550 mg/1 of sodium carbonate flows at a rate of 15 liter/hr downward through the beds. As a result of testing, no iodine, iodine ions, iodic acid ions and methyl iodine were detected. The amount of water the beds could treat was 60 times the total quantity of the filled resins.

Kinetics and mechanism of nitrobenzene hydrogenation to phenylhydroxylamine in rhenium thiocomplexes solutions

International Nuclear Information System (INIS)

Korenyako, G.I.; Belousov, V.M.

1985-01-01

A study was made on kinetics of nitrobenzene hydrogenation to phenylhydroxylamine in dimethylformamide solutions of rhenium thiocomplexes. The mechanism of hydrogenation was suggested. Formation of hydride catalyst complex represents the first stage of the process. Kinetic equation derived on the basis of suggested mechanism corresponds satisfactorily with experimental results. Thermodynamic parameters of separate process stages calculated on the basis of equilibrium constant values testify as well to the benefit of suggested mechanism

Comparative solution and solid-phase glycosylations toward a disaccharide library

DEFF Research Database (Denmark)

Agoston, K.; Kröger, Lars; Agoston, Agnes

2009-01-01

A comparative study on solution-phase and solid-phase oligosaccharide synthesis was performed. A 16-member library containing all regioisomers of Glc-Glc, Glc-Gal, Gal-Glc, and Gal-Gal disaccharides was synthesized both in solution and on solid phase. The various reaction conditions for different...

Exposure to buffer solution alters tendon hydration and mechanics.

Science.gov (United States)

Safa, Babak N; Meadows, Kyle D; Szczesny, Spencer E; Elliott, Dawn M

2017-08-16

A buffer solution is often used to maintain tissue hydration during mechanical testing. The most commonly used buffer solution is a physiological concentration of phosphate buffered saline (PBS); however, PBS increases the tissue's water content and decreases its tensile stiffness. In addition, solutes from the buffer can diffuse into the tissue and interact with its structure and mechanics. These bathing solution effects can confound the outcome and interpretation of mechanical tests. Potential bathing solution artifacts, including solute diffusion, and their effect on mechanical properties, are not well understood. The objective of this study was to measure the effects of long-term exposure of rat tail tendon fascicles to several concentrations (0.9-25%) of NaCl, sucrose, polyethylene glycol (PEG), and SPEG (NaCl+PEG) solutions on water content, solute diffusion, and mechanical properties. We found that with an increase in solute concentration the apparent water content decreased for all solution types. Solutes diffused into the tissue for NaCl and sucrose, however, no solute diffusion was observed for PEG or SPEG. The mechanical properties changed for both NaCl solutions, in particular after long-term (8h) incubation the modulus and equilibrium stress decreased compared to short-term (15min) for 25% NaCl, and the cross sectional area increased for 0.9% NaCl. However, the mechanical properties were unchanged for both PEG and SPEG except for minor alterations in stress relaxation parameters. This study shows that NaCl and sucrose buffer solutions are not suitable for long-term mechanical tests. We therefore propose using PEG or SPEG as alternative buffer solutions that after long-term incubation can maintain tissue hydration without solute diffusion and produce a consistent mechanical response. Copyright © 2017 Elsevier Ltd. All rights reserved.

Oscillatory mechanisms of process binding in memory.

Science.gov (United States)

Klimesch, Wolfgang; Freunberger, Roman; Sauseng, Paul

2010-06-01

A central topic in cognitive neuroscience is the question, which processes underlie large scale communication within and between different neural networks. The basic assumption is that oscillatory phase synchronization plays an important role for process binding--the transient linking of different cognitive processes--which may be considered a special type of large scale communication. We investigate this question for memory processes on the basis of different types of oscillatory synchronization mechanisms. The reviewed findings suggest that theta and alpha phase coupling (and phase reorganization) reflect control processes in two large memory systems, a working memory and a complex knowledge system that comprises semantic long-term memory. It is suggested that alpha phase synchronization may be interpreted in terms of processes that coordinate top-down control (a process guided by expectancy to focus on relevant search areas) and access to memory traces (a process leading to the activation of a memory trace). An analogous interpretation is suggested for theta oscillations and the controlled access to episodic memories. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

Thermodynamics of ionic processes in solutions

International Nuclear Information System (INIS)

Krestov, G.A.

1984-01-01

The present nitions about the mechanism of solvation of atomic-molecular particles and the structure of electrolyte and non electrolyte solutions are given. From common positions a wide range of interrelated problems (general and thermodynamic characteristic of ions, thermodynamic characteristic of ion solvation and various ionic reactions in solutions, structural changes of the solvent in the above processes etc...) is considered. The latest scientific data including those on the effect on the thermodynamio properties of low temperatures, various impurities (air, water), large ions, peculiarities of the structure of solvent molecules reflected. Considerable attention is given to new conceptions definitions, structural notions as well as theoretical and experimental methods of obtaining quantitative characteristics of ion solvation

Reaction mechanisms and evaluation of effective process operation for catalytic oxidation and coagulation by ferrous solution and hydrogen peroxide

Energy Technology Data Exchange (ETDEWEB)

Lee, S.H.; Moon, H.J.; Kim, Y.M. [Dept. of Environmental Engineering, Sangmyung Univ., Cheonan (Korea); Bae, W.K. [Dept. of Civil and Environmental Engineering, Hanyang Univ., Ansan, Kyounggi (Korea)

2003-07-01

This research was carried out to evaluate the removal efficiencies of COD{sub cr} and colour for the dyeing wastewater by ferrous solution and the different dosage of H{sub 2}O{sub 2} in Fenton process. In the case of H{sub 2}O{sub 2} divided dosage, 7:3 was more effective than 3:7 to remove COD{sub cr} and colour. The results showed that COD was mainly removed by Fenton coagulation, where the ferric ions are formed in the initial step of Fenton reaction. On the other hand colour was removed by Fenton oxidation rather than Fenton coagulation. This paper also aims at pursuing to investigate the effective removal mechanisms using ferrous ion coagulation, ferric ion coagulation and Fenton oxidation process. The removal mechanism of COD{sub cr} and colour was mainly coagulation by ferrous ion, ferric ion and Fenton oxidation. The removal efficiencies were dependent on the ferric ion amount at the beginning of the reaction. However the final removal efficiency of COD and colour was in the order of Fenton oxidation, ferric ion coagulation and ferrous ion coagulation. The reason of the highest removal efficiency by Fenton oxidation can be explained by the chain reactions with ferrous solution, ferric ion and hydrogen peroxide. (orig.)

Phosphorus removal from aqueous solution in parent and aluminum-modified eggshells: thermodynamics and kinetics, adsorption mechanism, and diffusion process.

Science.gov (United States)

Guo, Ziyan; Li, Jiuhai; Guo, Zhaobing; Guo, Qingjun; Zhu, Bin

2017-06-01

Parent and aluminum-modified eggshells were prepared and characterized with X-ray diffraction, specific surface area measurements, infrared spectroscopy, zeta potential, and scanning electron microscope, respectively. Besides, phosphorus adsorptions in these two eggshells at different temperatures and solution pH were carried out to study adsorption thermodynamics and kinetics as well as the mechanisms of phosphorus adsorption and diffusion. The results indicated that high temperature was favorable for phosphorus adsorption in parent and aluminum-modified eggshells. Alkaline solution prompted phosphorus adsorption in parent eggshell, while the maximum adsorption amount was achievable at pH 4 in aluminum-modified eggshell. Adsorption isotherms of phosphorus in these eggshells could be well described by Langmuir and Freundlich models. Phosphorus adsorption amounts in aluminum-modified eggshell were markedly higher compared to those in parent eggshell. Adsorption heat indicated that phosphorus adsorption in parent eggshell was a typically physical adsorption process, while chemical adsorption mechanism of ion exchange between phosphorus and hydroxyl groups on the surface of eggshells was dominated in aluminum-modified eggshell. The time-resolved uptake curves showed phosphorus adsorption in aluminum-modified eggshell was significantly faster than that in parent eggshell. Moreover, there existed two clear steps in time-resolved uptake curves of phosphorus in parent eggshell. Based on pseudo-second order kinetic model and intraparticle diffusion model, we inferred more than one process affected phosphorus adsorption. The first process was the diffusion of phosphorus through water to external surface and the opening of pore channel in the eggshells, and the second process was mainly related to intraparticle diffusion.

NMR studies of phase behaviour in polyacrylonitrile solutions

International Nuclear Information System (INIS)

Golightly, J.A.

1998-10-01

The aim of the thesis was to study the phase behaviour of aqueous polyacrylonitrile/NaSCN solutions using a variety of nuclear magnetic resonance techniques. Polyacrylonitrile (PAN) is the basis of the acrylic fibre industry, as such fibres contain at least 85% PAN. Despite this industrial importance, the available literature describing the phase behaviour of PAN in solution is far from comprehensive. Bulk 1 H NMR relaxation measurements were carried out over a wide range of concentrations and temperatures to probe the molecular dynamics of the PAN and water molecules. The relaxation data was found to be biexponential decay for all samples, the relative amplitudes of which were shown to be equal to the ratio of PAN protons to water protons. Both species were found to be in the regime of rapid molecular motion. Bulk 1 H NMR self diffusion measurements, using the PFGSTE technique, exhibited a bi-exponential decay of the echo amplitudes. By careful selection of the observation time, Δ, it was possible to independently probe the water and PAN translational diffusion. A background gradient, resulting from inhomogeneities of the magnetic field, complicated the analysis of the data and a novel polynomial least squares fitting procedure was devised to overcome this effect. The measured attenuation of the water diffusion coefficients (D∼10 -6 -10 -5 cm 2 s -1 ) with increasing PAN volume fraction was modelled according to various theories, including free volume and scaling laws. The study of the PAN diffusion coefficient (D∼10 -7 -10 -6 cm 2 s -1 ) was limited by the experimental constraints of the NMR spectrometer. A 1 H NMR one-dimensional imaging technique was used to study the non-solvent induced phase separation (coagulation) of a PAN solution. The time dependence of the measured profiles allowed observation of the coagulation process. A diffusion model was developed to fit the experimental data using a semi-infinite diffusion framework. The fitting parameters

Determination of TBP in nitric solutions of process

International Nuclear Information System (INIS)

Kuada, T.A.; Carvalho, E.I. de; Araujo, I. da C. de; Cohen, V.H.

1988-01-01

Heavy organic phases have been observed on some occasions during TBP extraction process. These products, described as red oils, were considered as the main cause for process failures, specially in evaporators and concentrators. In view of safety aspects it is necessary to control organic concentration in product and waste solutions. The proposed method involves the organic removal by chloroform as a first step, followed by purification onto a silica gel column. The results are given from analysing TBP and its degradation product (DBP) by gas chromatography. (author) [pt

Mercury Phase II Study - Mercury Behavior in Salt Processing Flowsheet

International Nuclear Information System (INIS)

Jain, V.; Shah, H.; Wilmarth, W. R.

2016-01-01

Mercury (Hg) in the Savannah River Site Liquid Waste System (LWS) originated from decades of canyon processing where it was used as a catalyst for dissolving the aluminum cladding of reactor fuel. Approximately 60 metric tons of mercury is currently present throughout the LWS. Mercury has long been a consideration in the LWS, from both hazard and processing perspectives. In February 2015, a Mercury Program Team was established at the request of the Department of Energy to develop a comprehensive action plan for long-term management and removal of mercury. Evaluation was focused in two Phases. Phase I activities assessed the Liquid Waste inventory and chemical processing behavior using a system-by-system review methodology, and determined the speciation of the different mercury forms (Hg+, Hg++, elemental Hg, organomercury, and soluble versus insoluble mercury) within the LWS. Phase II activities are building on the Phase I activities, and results of the LWS flowsheet evaluations will be summarized in three reports: Mercury Behavior in the Salt Processing Flowsheet (i.e. this report); Mercury Behavior in the Defense Waste Processing Facility (DWPF) Flowsheet; and Mercury behavior in the Tank Farm Flowsheet (Evaporator Operations). The evaluation of the mercury behavior in the salt processing flowsheet indicates, inter alia, the following: (1) In the assembled Salt Batches 7, 8 and 9 in Tank 21, the total mercury is mostly soluble with methylmercury (MHg) contributing over 50% of the total mercury. Based on the analyses of samples from 2H Evaporator feed and drop tanks (Tanks 38/43), the source of MHg in Salt Batches 7, 8 and 9 can be attributed to the 2H evaporator concentrate used in assembling the salt batches. The 2H Evaporator is used to evaporate DWPF recycle water. (2) Comparison of data between Tank 21/49, Salt Solution Feed Tank (SSFT), Decontaminated Salt Solution Hold Tank (DSSHT), and Tank 50 samples suggests that the total mercury as well as speciated

A novel mechanical model for phase-separation in debris flows

Science.gov (United States)

Pudasaini, Shiva P.

2015-04-01

Understanding the physics of phase-separation between solid and fluid phases as a two-phase mass moves down slope is a long-standing challenge. Here, I propose a fundamentally new mechanism, called 'separation-flux', that leads to strong phase-separation in avalanche and debris flows. This new model extends the general two-phase debris flow model (Pudasaini, 2012) to include a separation-flux mechanism. The new flux separation mechanism is capable of describing and controlling the dynamically evolving phase-separation, segregation, and/or levee formation in a real two-phase, geometrically three-dimensional debris flow motion and deposition. These are often observed phenomena in natural debris flows and industrial processes that involve the transportation of particulate solid-fluid mixture material. The novel separation-flux model includes several dominant physical and mechanical aspects that result in strong phase-separation (segregation). These include pressure gradients, volume fractions of solid and fluid phases and their gradients, shear-rates, flow depth, material friction, viscosity, material densities, boundary structures, gravity and topographic constraints, grain shape, size, etc. Due to the inherent separation mechanism, as the mass moves down slope, more and more solid particles are brought to the front, resulting in a solid-rich and mechanically strong frontal surge head followed by a weak tail largely consisting of the viscous fluid. The primary frontal surge head followed by secondary surge is the consequence of the phase-separation. Such typical and dominant phase-separation phenomena are revealed here for the first time in real two-phase debris flow modeling and simulations. However, these phenomena may depend on the bulk material composition and the applied forces. Reference: Pudasaini, Shiva P. (2012): A general two-phase debris flow model. J. Geophys. Res., 117, F03010, doi: 10.1029/2011JF002186.

Solution of a Complex Least Squares Problem with Constrained Phase.

Science.gov (United States)

Bydder, Mark

2010-12-30

The least squares solution of a complex linear equation is in general a complex vector with independent real and imaginary parts. In certain applications in magnetic resonance imaging, a solution is desired such that each element has the same phase. A direct method for obtaining the least squares solution to the phase constrained problem is described.

Microstructure, mechanical property and metal release of As-SLM CoCrW alloy under different solution treatment conditions.

Science.gov (United States)

Lu, Yanjin; Wu, Songquan; Gan, Yiliang; Zhang, Shuyuan; Guo, Sai; Lin, Junjie; Lin, Jinxin

2015-03-01

In the study, the microstructure, mechanical property and metal release behavior of selective laser melted CoCrW alloys under different solution treatment conditions were systemically investigated to assess their potential use in orthopedic implants. The effects of the solution treatment on the microstructure, mechanical properties and metal release were systematically studied by OM, SEM, XRD, tensile test, and ICP-AES, respectively. The XRD indicated that during the solution treatment the alloy underwent the transformation of γ-fcc to ε-hcp phase; the ε-hcp phase nearly dominated in the alloy when treated at 1200°C following the water quenching; the results from OM, SEM showed that the microstructural change was occurred under different solution treatments; solution at 1150°C with furnace cooling contributed to the formation of larger precipitates at the grain boundary regions, while the size and number of the precipitates was decreased as heated above 1100°C with the water quenching; moreover, the diamond-like structure was invisible at higher solution temperature over 1150°C following water quenching; compared with the furnace cooling, the alloy quenched by water showed excellent mechanical properties and low amount of metal release; as the alloy heated at 1200°C, the mechanical properties of the alloy reached their optimum combination at UTS=1113.6MPa, 0.2%YS=639.5MPa, and E%=20.1%, whilst showed the lower total quantity of metal release. It is suggested that a proper solution treatment is an efficient strategy for improving the mechanical properties and corrosion resistance of As-SLM CoCrW alloy that show acceptable tensile ductility. Copyright © 2015 Elsevier Ltd. All rights reserved.

Synthesis of Copper-Antimony-Sulfide Nanocrystals for Solution-Processed Solar Cells.

Science.gov (United States)

Suehiro, Satoshi; Horita, Keisuke; Yuasa, Masayoshi; Tanaka, Tooru; Fujita, Katsuhiko; Ishiwata, Yoichi; Shimanoe, Kengo; Kida, Tetsuya

2015-08-17

The p-type nanocrystals (NCs) of copper-based chalcogenides, such as CuInSe2 and Cu2ZnSnS4, have attracted increasing attention in photovoltaic applications due to their potential to produce cheap solution-processed solar cells. Herein, we report the synthesis of copper-antimony-sulfide (CAS) NCs with different crystal phases including CuSbS2, Cu3SbS4, and Cu12Sb4S13. In addition, their morphology, crystal phase, and optical properties were characterized using transmission electron microscopy, X-ray diffractometry, UV-vis-near-IR spectroscopy, and photoemission yield spectroscopy. The morphology, crystal phase, and electronic structure were significantly dependent on the chemical composition in the CAS system. Devices were fabricated using particulate films consisting of CAS NCs prepared by spin coating without a high-temperature treatment. The CAS NC-based devices exhibited a diode-like current-voltage characteristic when coupled with an n-type CdS layer. In particular, the CuSbS2 NC devices exhibited photovoltaic responses under simulated sunlight, demonstrating its applicability for use in solution-processed solar cells.

Colloidal quantum dot solids for solution-processed solar cells

KAUST Repository

Yuan, Mingjian

2016-02-29

Solution-processed photovoltaic technologies represent a promising way to reduce the cost and increase the efficiency of solar energy harvesting. Among these, colloidal semiconductor quantum dot photovoltaics have the advantage of a spectrally tuneable infrared bandgap, which enables use in multi-junction cells, as well as the benefit of generating and harvesting multiple charge carrier pairs per absorbed photon. Here we review recent progress in colloidal quantum dot photovoltaics, focusing on three fronts. First, we examine strategies to manage the abundant surfaces of quantum dots, strategies that have led to progress in the removal of electronic trap states. Second, we consider new device architectures that have improved device performance to certified efficiencies of 10.6%. Third, we focus on progress in solution-phase chemical processing, such as spray-coating and centrifugal casting, which has led to the demonstration of manufacturing-ready process technologies.

Fluid mechanics problems and solutions

CERN Document Server

Spurk, Joseph H

1997-01-01

his collection of over 200 detailed worked exercises adds to and complements the textbook Fluid Mechanics by the same author, and illustrates the teaching material through examples. In the exercises the fundamental concepts of Fluid Mechanics are applied to obtaining the solution of diverse concrete problems, and in doing this the student's skill in the mathematical modeling of practical problems is developed. In addition, 30 challenging questions without detailed solutions have been included, and while lecturers will find these questions suitable for examinations and tests, the student himself can use them to check his understanding of the subject.

Elucidating the weak protein-protein interaction mechanisms behind the liquid-liquid phase separation of a mAb solution by different types of additives.

Science.gov (United States)

Wu, Guoliang; Wang, Shujing; Tian, Zhou; Zhang, Ning; Sheng, Han; Dai, Weiguo; Qian, Feng

2017-11-01

Liquid-liquid phase separation (LLPS) has long been observed during the physical stability investigation of therapeutic protein formulations. The buffer conditions and the presence of various excipients are thought to play important roles in the formulation development of monoclonal antibodies (mAbs). In this study, the effects of several small-molecule excipients (histidine, alanine, glycine, sodium phosphate, sodium chloride, sorbitol and sucrose) with diverse physical-chemical properties on LLPS of a model IgG1 (JM2) solutions were investigated by multiple techniques, including UV-vis spectroscopy, circular dichroism, differential scanning calorimetry/fluorimetry, size exclusion chromatography and dynamic light scattering. The LLPS of JM2 was confirmed to be a thermodynamic equilibrium process with no structural changes or irreversible aggregation of proteins. Phase diagrams of various JM2 formulations were constructed, suggesting that the phase behavior of JM2 was dependent on the solution pH, ionic strength and the presence of other excipients such as glycine, alanine, sorbitol and sucrose. Furthermore, we demonstrated that for this mAb, the interaction parameter (k D ) determined at low protein concentration appeared to be a good predictor for the occurrence of LLPS at high concentration. Copyright © 2017 Elsevier B.V. All rights reserved.

Phase evolution and thermal stability of 2 Mg–Cu alloys processed by mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

Martínez, C., E-mail: carola.martinezu@usach.cl [Departamento de Ingeniería Metalúrgica, Facultad de Ingeniería, Universidad de Santiago de Chile, Av. Lib. Bernardo O’Higgins 3363, Casilla de correo 10233, Santiago (Chile); Ordoñez, S., E-mail: stella.ordonez@usach.cl [Departamento de Ingeniería Metalúrgica, Facultad de Ingeniería, Universidad de Santiago de Chile, Av. Lib. Bernardo O’Higgins 3363, Casilla de correo 10233, Santiago (Chile); Guzmán, D. [Departamento de Ingeniería en Metalurgia, Facultad de Ingeniería, Universidad de Atacama y CRIDESAT, Av. Copayapu 485, Casilla de Correo 240, Copiapó (Chile); Serafini, D. [Departamento de Física, Facultad de Ciencia, Universidad de Santiago de Chile, Av. Lib. Bernardo O’Higgins 3363, Casilla de correo 307, Santiago (Chile); Iturriza, I. [CEIT, Manuel de Lardizábal 15, 20018 San Sebastián, España (Spain); Bustos, O. [Departamento de Ingeniería Metalúrgica, Facultad de Ingeniería, Universidad de Santiago de Chile, Av. Lib. Bernardo O’Higgins 3363, Casilla de correo 10233, Santiago (Chile)

2013-12-25

Highlights: •Study of phase evolution of elemental powders Mg and Cu by mechanical alloying. •The presence of an amorphous precursor which crystallizes to Mg{sub 2}Cu can be observed. •Establishing the sequence of phase transformations leading to the formation of Mg{sub 2}Cu. •The feasibility to obtain Mg{sub 2}Cu by means two possible routes has been established. -- Abstract: Phase evolution during mechanical alloying (MA) of elemental Mg and Cu powders and their subsequent heat treatment is studied. Elemental Mg and Cu powders in a 2:1 atomic ratio were mechanically alloyed in a SPEX 8000D mill using a 10:1 ball-to-powder ratio. X-ray diffraction (XRD) shows that the formation of the intermetallic Mg{sub 2}Cu takes place between 3 and 4 h of milling, although traces of elemental Cu are still present after 10 h of milling. The thermal behavior of different powder mixtures was evaluated by differential scanning calorimetry (DSC). The combination of DSC, heat treatment and XRD has shown a sequence of phase transformations that results in the intermetallic Mg{sub 2}Cu from an amorphous precursor. This amorphous phase is converted into Mg{sub 2}Cu by heating at low temperature (407 K). Short MA times and the formation of the amorphous precursor, together with its subsequent transformation into Mg{sub 2}Cu at low temperatures; represent an advantageous alternative route for its preparation.

CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES: Molecular Dynamics Study of Stability of Solid Solutions and Amorphous Phase in the Cu-Al System

Science.gov (United States)

Yang, Bin; Lai, Wen-Sheng

2009-06-01

The relative stability of fcc and bcc solid solutions and amorphous phase with different compositions in the Cu-Al system is studied by molecular dynamics simulations with n-body potentials. For Cu1-xAlx alloys, the calculations show that the fcc solid solution has the lowest energies in the composition region with x 0.72, while the bee solid solution has the lowest energies in the central composition range, in agreement with the ball-milling experiments that a single bcc solid solution with 0.30 < x < 0.70 is obtained. The evolution of structures in solid solutions and amorphous phase is studied by the coordination number (CN) and bond-length analysis so as to unveil the underlying physics. It is found that the energy sequence among three phases is determined by the competition in energy change originating from the bond length and CNs (or the number of bonds).

Quantum mechanical study of solvent effects in a prototype SN2 reaction in solution: Cl- attack on CH3Cl.

Science.gov (United States)

Kuechler, Erich R; York, Darrin M

2014-02-07

The nucleophilic attack of a chloride ion on methyl chloride is an important prototype SN2 reaction in organic chemistry that is known to be sensitive to the effects of the surrounding solvent. Herein, we develop a highly accurate Specific Reaction Parameter (SRP) model based on the Austin Model 1 Hamiltonian for chlorine to study the effects of solvation into an aqueous environment on the reaction mechanism. To accomplish this task, we apply high-level quantum mechanical calculations to study the reaction in the gas phase and combined quantum mechanical/molecular mechanical simulations with TIP3P and TIP4P-ew water models and the resulting free energy profiles are compared with those determined from simulations using other fast semi-empirical quantum models. Both gas phase and solution results with the SRP model agree very well with experiment and provide insight into the specific role of solvent on the reaction coordinate. Overall, the newly parameterized SRP Hamiltonian is able to reproduce both the gas phase and solution phase barriers, suggesting it is an accurate and robust model for simulations in the aqueous phase at greatly reduced computational cost relative to comparably accurate ab initio and density functional models.

Microstructure and mechanical properties of a novel Ti–Al–Cr–Fe titanium alloy after solution treatment

International Nuclear Information System (INIS)

Wang, Zhenguo; Cai, Haijiao; Hui, Songxiao

2015-01-01

Highlights: • Microstructure and mechanical properties of a novel Ti–3.0Al–3.7Cr–2.0Fe alloy were studied. • The effects of cooling rates and solution temperature were considered. • The strength–ductility combination were investigated through different heat treatment. - Abstract: The relationship between microstructure and mechanical properties of a novel Ti–3.0Al–3.7Cr–2.0Fe alloy were studied. The effects of cooling rates and solution temperature were considered. The analysis methods of optical microscope (OM), X-ray diffractometer (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) were used. The results indicate that β and α phase in this alloy are obtained after solution treated at 1183 K on the cooling ways of air cooling and furnace cooling; and β and α″ martensite are observed after quenching in water. Besides, the volume of α phase is decreased with increasing solution temperature. In the present study, the ultimate strength 1065 MPa with 12.0% in elongation of the alloy is acquired under the heat treatment condition of 1183 K/30 min/AC, and the strength–ductility combination in this case is also the best. Under the heat treatment condition of 1183 K/30 min/WQ, the elasticity modulus of the alloy is only 91.3 GPa, as a result of the lower elasticity modulus of β phase

Formation of nanocrystalline and amorphous phase of Al-Pb-Si-Sn-Cu powder during mechanical alloying

International Nuclear Information System (INIS)

Ran Guang; Zhou Jingen; Xi Shengqi; Li Pengliang

2006-01-01

Al-15%Pb-4%Si-1%Sn-1.5%Cu alloys (mass fraction, %) were prepared by mechanical alloying (MA). Phase transformation and microstructure characteristics of the alloy powders were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the nanocrystalline supersaturated solid solutions and amorphous phase in the powders are obtained during MA. The effect of ball milling is more evident to lead than to aluminum. During MA, the mixture powders are firstly fined, alloyed, nanocrystallized and then the nanocrystalline partly transforms to amorphous phase. A thermodynamic model is developed based on semi-experimental theory of Miedema to calculate the driving force for phase evolution. The thermodynamic analysis shows that there is no chemical driving force to form a crystalline solid solution from the elemental components. But for the amorphous phase, the Gibbs free energy is higher than 0 for the alloy with lead content in the ranges of 0-86.8 at.% and 98.4-100 at.% and lower than 0 in range of 86.8-98.4 at.%. For the Al-2.25 at.%Pb (Al-15%Pb, mass fraction, %), the driving force for formation of amorphization and nanocrystalline supersaturated solid solutions are provided not by the negative heat of mixing but by mechanical work

[Nasal submicron emulsion of Scutellariae Radix extract preparation technology research based on phase transfer of solute technology].

Science.gov (United States)

Shi, Ya-jun; Shi, Jun-hui; Chen, Shi-bin; Yang, Ming

2015-07-01

Based on the demand of nasal drug delivery high drug loadings, using the unique phase transfer of solute, integrating the phospholipid complex preparation and submicron emulsion molding process of Scutellariae Radix extract, the study obtained the preparation of the high drug loadings submicron emulsion of Scutellariae Radix extract. In the study of drug solution dispersion method, the uniformity of drug dispersed as the evaluation index, the traditional mixing method, grinding, homogenate and solute phase transfer technology were investigated, and the solute phase transfer technology was adopted in the last. With the adoption of new technology, the drug loading capacity reached 1.33% (phospholipid complex was 4%). The drug loading capacity was improved significantly. The transfer of solute method and timing were studied as follows,join the oil phase when the volume of phospholipid complex anhydrous ethanol solution remaining 30%, the solute phase transfer was completed with the continued recycling of anhydrous ethanol. After drug dissolved away to oil phase, the preparation technology of colostrum was determined with the evaluation index of emulsion droplet form. The particle size of submicron emulsion, PDI and stability parameters were used as evaluation index, orthogonal methodology were adopted to optimize the submicron emulsion ingredient and main influential factors of high pressure homogenization technology. The optimized preparation technology of Scutellariae Radix extract nasal submicron emulsion is practical and stable.

Self-Functionalization Behind a Solution-Processed NiOx Film Used As Hole Transporting Layer for Efficient Perovskite Solar Cells.

Science.gov (United States)

Ciro, John; Ramírez, Daniel; Mejía Escobar, Mario Alejandro; Montoya, Juan Felipe; Mesa, Santiago; Betancur, Rafael; Jaramillo, Franklin

2017-04-12

Fabrication of solution-processed perovskite solar cells (PSCs) requires the deposition of high quality films from precursor inks. Frequently, buffer layers of PSCs are formed from dispersions of metal oxide nanoparticles (NPs). Therefore, the development of trustable methods for the preparation of stable colloidal NPs dispersions is crucial. In this work, a novel approach to form very compact semiconducting buffer layers with suitable optoelectronic properties is presented through a self-functionalization process of the nanocrystalline particles by their own amorphous phase and without adding any other inorganic or organic functionalization component or surfactant. Such interconnecting amorphous phase composed by residual nitrate, hydroxide, and sodium ions, proved to be fundamental to reach stable colloidal dispersions and contribute to assemble the separate crystalline nickel oxide NPs in the final film, resulting in a very homogeneous and compact layer. A proposed mechanism behind the great stabilization of the nanoparticles is exposed. At the end, the self-functionalized nickel oxide layer exhibited high optoelectronic properties enabling perovskite p-i-n solar cells as efficient as 16.6% demonstrating the pertinence of the presented strategy to obtain high quality buffer layers processed in solution at room temperature.

Microstructures and mechanical properties of two-phase alloys based on NbCr{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Chen, K.C.; Kotula, P.G.; Cady, C.M.; Mauro, M.E.; Thoma, D.J.

1999-07-01

A two-phase, NbCrTi alloy (bcc + C15 Laves phase) has been developed using several alloy design methodologies. In efforts to understand processing-microstructure-property relationships, different processing routes were employed. The resulting microstructures and mechanical properties are discussed and compared. Plasma arc melted (PAM) samples served to establish baseline, as-cast properties. In addition, a novel processing technique, involving decomposition of a supersaturated and metastable precursor phase during hot isostatic pressing (HIP), was used to produce a refined, equilibrium two-phase microstructure. Quasi-static compression tests as a function of temperature were performed on both alloy types. Different deformation mechanisms were encountered based upon temperature and microstructure.

Solution-Processed Carbon Nanotube True Random Number Generator.

Science.gov (United States)

Gaviria Rojas, William A; McMorrow, Julian J; Geier, Michael L; Tang, Qianying; Kim, Chris H; Marks, Tobin J; Hersam, Mark C

2017-08-09

With the growing adoption of interconnected electronic devices in consumer and industrial applications, there is an increasing demand for robust security protocols when transmitting and receiving sensitive data. Toward this end, hardware true random number generators (TRNGs), commonly used to create encryption keys, offer significant advantages over software pseudorandom number generators. However, the vast network of devices and sensors envisioned for the "Internet of Things" will require small, low-cost, and mechanically flexible TRNGs with low computational complexity. These rigorous constraints position solution-processed semiconducting single-walled carbon nanotubes (SWCNTs) as leading candidates for next-generation security devices. Here, we demonstrate the first TRNG using static random access memory (SRAM) cells based on solution-processed SWCNTs that digitize thermal noise to generate random bits. This bit generation strategy can be readily implemented in hardware with minimal transistor and computational overhead, resulting in an output stream that passes standardized statistical tests for randomness. By using solution-processed semiconducting SWCNTs in a low-power, complementary architecture to achieve TRNG, we demonstrate a promising approach for improving the security of printable and flexible electronics.

Imaginary eigenvalue solution in RPA and phase transition

International Nuclear Information System (INIS)

Yao Yujie; Jing Xiaogong; Zhao Guoquan; Wu Shishu

1993-01-01

The phase transition (PT) of a many-particle system with a close-shell configuration, the stability of the Hartree-Fock (HF) solution and the random phase approximation (RPA) are studied by means of a generalized three-level solvable model. The question whether the occurrence of an imaginary eigenvalue solution in RPA (OISA) may be considered as a signature of PT is explored in some detail. It is found that there is no close relation between OISA and PT. Generally, OISA shows that RPA becomes poor

Closed-form solutions for linear regulator design of mechanical systems including optimal weighting matrix selection

Science.gov (United States)

Hanks, Brantley R.; Skelton, Robert E.

1991-01-01

Vibration in modern structural and mechanical systems can be reduced in amplitude by increasing stiffness, redistributing stiffness and mass, and/or adding damping if design techniques are available to do so. Linear Quadratic Regulator (LQR) theory in modern multivariable control design, attacks the general dissipative elastic system design problem in a global formulation. The optimal design, however, allows electronic connections and phase relations which are not physically practical or possible in passive structural-mechanical devices. The restriction of LQR solutions (to the Algebraic Riccati Equation) to design spaces which can be implemented as passive structural members and/or dampers is addressed. A general closed-form solution to the optimal free-decay control problem is presented which is tailored for structural-mechanical system. The solution includes, as subsets, special cases such as the Rayleigh Dissipation Function and total energy. Weighting matrix selection is a constrained choice among several parameters to obtain desired physical relationships. The closed-form solution is also applicable to active control design for systems where perfect, collocated actuator-sensor pairs exist.

Photo-stability study of a solution-processed small molecule solar cell system: correlation between molecular conformation and degradation.

Science.gov (United States)

Newman, Michael J; Speller, Emily M; Barbé, Jérémy; Luke, Joel; Li, Meng; Li, Zhe; Wang, Zhao-Kui; Jain, Sagar M; Kim, Ji-Seon; Lee, Harrison Ka Hin; Tsoi, Wing Chung

2018-01-01

Solution-processed organic small molecule solar cells (SMSCs) have achieved efficiency over 11%. However, very few studies have focused on their stability under illumination and the origin of the degradation during the so-called burn-in period. Here, we studied the burn-in period of a solution-processed SMSC using benzodithiophene terthiophene rhodamine:[6,6]-phenyl C 71 butyric acid methyl ester (BTR:PC 71 BM) with increasing solvent vapour annealing time applied to the active layer, controlling the crystallisation of the BTR phase. We find that the burn-in behaviour is strongly correlated to the crystallinity of BTR. To look at the possible degradation mechanisms, we studied the fresh and photo-aged blend films with grazing incidence X-ray diffraction, UV-vis absorbance, Raman spectroscopy and photoluminescence (PL) spectroscopy. Although the crystallinity of BTR affects the performance drop during the burn-in period, the degradation is found not to originate from the crystallinity changes of the BTR phase, but correlates with changes in molecular conformation - rotation of the thiophene side chains, as resolved by Raman spectroscopy which could be correlated to slight photobleaching and changes in PL spectra.

Three-Dimensional ZnO Hierarchical Nanostructures: Solution Phase Synthesis and Applications

Directory of Open Access Journals (Sweden)

Xiaoliang Wang

2017-11-01

Full Text Available Zinc oxide (ZnO nanostructures have been studied extensively in the past 20 years due to their novel electronic, photonic, mechanical and electrochemical properties. Recently, more attention has been paid to assemble nanoscale building blocks into three-dimensional (3D complex hierarchical structures, which not only inherit the excellent properties of the single building blocks but also provide potential applications in the bottom-up fabrication of functional devices. This review article focuses on 3D ZnO hierarchical nanostructures, and summarizes major advances in the solution phase synthesis, applications in environment, and electrical/electrochemical devices. We present the principles and growth mechanisms of ZnO nanostructures via different solution methods, with an emphasis on rational control of the morphology and assembly. We then discuss the applications of 3D ZnO hierarchical nanostructures in photocatalysis, field emission, electrochemical sensor, and lithium ion batteries. Throughout the discussion, the relationship between the device performance and the microstructures of 3D ZnO hierarchical nanostructures will be highlighted. This review concludes with a personal perspective on the current challenges and future research.

Phase Evolution of YBa2Cu3O7-x films by all-chemical solution deposition route for coated conductors

DEFF Research Database (Denmark)

Yue, Zhao; Tang, Xiao; Wu, Wei

2014-01-01

In order to understand the all-chemical-solution-deposition (CSD) processes for manufacturing coated conductors, we investigated the phase evolution of YBa2Cu3O7 (YBCO) films deposited by a low-fluorine metal-organic solution deposition (LF-MOD) method on CSD derived Ce0.9La0.1O2/Gd2Zr2O7/Ni......W. It is shown that the phase transition from the pyrolyzed film to fully converted YBCO film in the LF-MOD process is similar to that in typical trifluoroacetates-metal organic deposition (TFA-MOD) processes even though the amount of TFA in the solution is reduced by almost one half compared with typical TFA...

Kinetics and mechanism of the biodegradation of PLA/clay nanocomposites during thermophilic phase of composting process.

Science.gov (United States)

Stloukal, Petr; Pekařová, Silvie; Kalendova, Alena; Mattausch, Hannelore; Laske, Stephan; Holzer, Clemens; Chitu, Livia; Bodner, Sabine; Maier, Guenther; Slouf, Miroslav; Koutny, Marek

2015-08-01

The degradation mechanism and kinetics of polylactic acid (PLA) nanocomposite films, containing various commercially available native or organo-modified montmorillonites (MMT) prepared by melt blending, were studied under composting conditions in thermophilic phase of process and during abiotic hydrolysis and compared to the pure polymer. Described first order kinetic models were applied on the data from individual experiments by using non-linear regression procedures to calculate parameters characterizing aerobic composting and abiotic hydrolysis, such as carbon mineralization, hydrolysis rate constants and the length of lag phase. The study showed that the addition of nanoclay enhanced the biodegradation of PLA nanocomposites under composting conditions, when compared with pure PLA, particularly by shortening the lag phase at the beginning of the process. Whereas the lag phase of pure PLA was observed within 27days, the onset of CO2 evolution for PLA with native MMT was detected after just 20days, and from 13 to 16days for PLA with organo-modified MMT. Similarly, the hydrolysis rate constants determined tended to be higher for PLA with organo-modified MMT, particularly for the sample PLA-10A with fastest degradation, in comparison with pure PLA. The acceleration of chain scission in PLA with nanoclays was confirmed by determining the resultant rate constants for the hydrolytical chain scission. The critical molecular weight for the hydrolysis of PLA was observed to be higher than the critical molecular weight for onset of PLA mineralization, suggesting that PLA chains must be further shortened so as to be assimilated by microorganisms. In conclusion, MMT fillers do not represent an obstacle to acceptance of the investigated materials in composting facilities. Copyright © 2015 Elsevier Ltd. All rights reserved.

Preparation of multishell ICF target plastic-foam cushion materials by thermally induced phase-inversion processes

International Nuclear Information System (INIS)

Young, A.T.; Moreno, D.K.; Marsters, R.G.

1981-01-01

Homogenous, low-density plastic foams for ICF targets have been prepared by thermally induced phase inversion processes. Uniform, open cell foams have been obtained by the rapid freezing of water solutions of modified cellulose polymers with densities in the range of 5 mg/cm 3 to 0.7 mg/cm 3 and respective average cell sizes of 2 to 40 micrometers. In addition, low-density, microcellular foams have been prepared from the hydrocarbon polymer poly(4-methyl-l-pentene) via a similar phase inversion process using homogenous solutions in organic solvents. These foams have densities from 2 to 5 mg/cm 3 and average cell sizes of 20 micrometers. The physical-chemical aspects of the thermally induced phase inversion process is presented

On the phase evolution of AlCoCrCuFeMnSix high entropy alloys prepared by mechanical alloying and arc melting route

Science.gov (United States)

Kumar, Anil; Chopkar, Manoj

2018-05-01

Effect of Si addition on phase formation of AlCoCrCuFeMnSix (x=0, 0.3, 0.6 and 0.9) high entropy alloy have been investigated in this work. The alloys are prepared by mechanical alloying and vacuum arc melting technique. The X-ray diffraction results reveals the formation of mixture of face centered and body centered cubic solid solution phases in milled powders. The addition of Si favours body centered cubic structure formation during milling process. Whereas, after melting the milled powders, body centered phases formed during milling is partial transformed into sigma phases. XRD results were also correlated with the SEM elemental mapping of as casted samples. Addition of Si favours σ phase formation in the as cast samples.

Analysis of Americium in Transplutonium Process Solutions

International Nuclear Information System (INIS)

Ferguson, R.B.

2001-01-01

One of the more difficult analyses in the transplutonium field is the determination of americium at trace levels in a complex matrix such as a process dissolver solution. Because of these conditions a highly selective separation must precede the measurement of americium. The separation technique should be mechanically simple to permit remote operation with master-slave manipulators. For subsequent americium measurement by the mass spectroscopic isotopic-dilution technique, plutonium and curium interferences must also have been removed

Travelling wave solutions for a surface wave equation in fluid mechanics

Directory of Open Access Journals (Sweden)

Tian Yi

2016-01-01

Full Text Available This paper considers a non-linear wave equation arising in fluid mechanics. The exact traveling wave solutions of this equation are given by using G'/G-expansion method. This process can be reduced to solve a system of determining equations, which is large and difficult. To reduce this process, we used Wu elimination method. Example shows that this method is effective.

Solutions for the food processing industry; Shokuhin seizogyo solution

Energy Technology Data Exchange (ETDEWEB)

Toda, T; Iwami, N [Fuji Electric Co. Ltd., Tokyo (Japan)

1999-09-10

To improve quality control and maintain stable operation, the food processing industry requires problem solutions in total, including not only processing and operation control divisions but also quality control, design and production technology, and maintenance divisions. This paper describes solutions for HACCP (hazard analysis critical control point) support, quality control, and maintenance, in order to improve the quality level, ensure traceability and realize stable processing operations. (author)

Formation of the second organic phase during uranyl nitrate extraction from aqueous solution by 30% tributylphosphate solution in paraffin

International Nuclear Information System (INIS)

Yhrkin, V.G.

1996-01-01

For extraction systems aqueous solution of uranyl nitrate-30% solution of tributylphosphate in individual paraffins from C 13 to C 17 the influence of the second organic phase of uranyl nitrate concentration in aqueous and organic phases, the length of hydrocarbon chain of paraffin hydrocarbon and temperature from 25 to 50 deg C on formation conditions has been defected. A special method of achieving the conditions of organic phase stratification from three-phase region, involving definition of equilibrium phases composition by density and refractive index, has been elaborated for more precise definition of organic phase homogeneity region. It has been revealed that without addition of nitric acid to uranyl nitrate solution the organic phase homogeneity limits can be achieved solely on paraffins C 15 , C 16 and C 17 and only under conditions similar to equeous phase saturation in terms of uranyl nitrate. 16 refs., 2 figs

Phase transitions in multiplicative competitive processes

International Nuclear Information System (INIS)

Shimazaki, Hideaki; Niebur, Ernst

2005-01-01

We introduce a discrete multiplicative process as a generic model of competition. Players with different abilities successively join the game and compete for finite resources. Emergence of dominant players and evolutionary development occur as a phase transition. The competitive dynamics underlying this transition is understood from a formal analogy to statistical mechanics. The theory is applicable to bacterial competition, predicting novel population dynamics near criticality

Effects of thermo-mechanical treatment and microalloying with Cr, Nb and Ti on phase transformation in C-Mn steel strips produced by compact strip production process

International Nuclear Information System (INIS)

Zhu, Y.Z.; Liang, D.M.; Li, J.C.; Xu, J.P.; Xue, Z.L.

2011-01-01

Highlights: → The order of solid solution of carbides influences phase transformation of C-Mn steel in cooling. → Evidences of early stage of solid solution of carbides were provides in the paper. → Transitional state evidences such as carbon enriched regions were observed in this study. - Abstract: The C-Mn steel strips microalloyed with Cr, Nb, Ti was produced by compact strip production process and then heat-treated under different conditions. Optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and transmission electron microscopy were used to investigate phase transformations in the steel after different treatments. It was revealed that the phase transformations upon quenching were greatly affected by the austenization temperature and time. When the steel was annealed at 950 deg. C, carbides of Cr, Mn and Fe were dissolved dramatically, while carbides of Nb and Ti are relatively stable at this temperature. When the temperature increases to 1100 deg. C, the carbides of Nb were dissolved rapidly, while the carbides of Ti still show somewhat stable (partial dissolution). Annealing time influences both the amount and the shapes of carbides in the steel, which leads to different phase transformations in the following air cooling processes. Grain growth in the steel in annealing process strongly depends on the dissolution of carbides on grain boundaries. Additionally, a subsequent rolling after annealing treatment at 950 deg. C lead to obvious precipitation of carbides of Ti and Nb in the steel.

Phase transition in Smsub(1-x)Gdsub(x)S and Smsub(1-x)Tmsub(x)S solid solutions under pressure

International Nuclear Information System (INIS)

Kaminskij, V.V.; Stepanov, N.N.; Romanova, M.V.

1985-01-01

Experiments are conducted on studying the effect of the n quantity on Psub(pt) (phase transition pressure) for SmS and systems of solid solutions Smsub(1-x)Gdsub(x)S and Smsub(1-x)Tmsub(x)S with conductivity electron concentrations approximately 10 19 -10 21 cm -3 corresponding to the semiconducting phase of these solutions. The investigated monocrystal samples have been prepared by the method of planar crystallization from the melt, have been chipped off over the cleavage planes [100], their characteristic sizes not exceeding 2 mm. Samples of the Smsub(1-x)Tmsub(x)S system were polycrystalline and they had characteristic dimensions of approximately 3mm. Concentration of conductivity electrons has been determined from measurements of the Hall constant. Hydrostatic compression of the samples has been exercised in a piston high-pressure chamber at T=300 K. The observed electric conductivity jump determined by the standard d.c. compensation technique was a criterion of the presence of the phase transition to the metal state. Dependences of Psub(pt) in SmS base solid solutions with approximately 10 19 -10 21 cm -3 concentration of conductivity electrons have similar tendency in behaviour: a certain increase in the phase transition pressure with n growth and then its drop at n approaching concentrations corresponding to compositions close to critical ones for the semiconductor-metal phase transition in any system of solid solutions. If the first mechanism prevails at small as then further on the second mechanism swelling by a power law with a high index plays the main role

Mathematical modeling of phase interaction taking place in materials processing

International Nuclear Information System (INIS)

Zinigrad, M.

2002-01-01

The quality of metallic products depends on their composition and structure. The composition and the structure are determined by various physico-chemical and technological factors. One of the most important and complicated problems in the modern industry is to obtain materials with required composition, structure and properties. For example, deep refining is a difficult task by itself, but the problem of obtaining the material with the required specific level of refining is much more complicated. It will take a lot of time and will require a lot of expanses to solve this problem empirically and the result will be far from the optimal solution. The most effective way to solve such problems is to carry out research in two parallel direction. Comprehensive analysis of thermodynamics, kinetics and mechanisms of the processes taking place at solid-liquid-gaseous phase interface and building of the clear well-based physico-chemical model of the above processes taking into account their interaction. Development of mathematical models of the specific technologies which would allow to optimize technological processes and to ensure obtaining of the required properties of the products by choosing the optimal composition of the raw materials. We apply the above unique methods. We developed unique methods of mathematical modeling of phase interaction at high temperatures. These methods allows us to build models taking into account: thermodynamic characteristics of the processes, influence of the initial composition and temperature on the equilibrium state of the reactions, kinetics of homogeneous and heterogeneous processes, influence of the temperature, composition, speed of the gas flows, hydrodynamic and thermal factors on the velocity of the chemical and diffusion processes. The models can be implemented in optimization of various metallurgical processes in manufacturing of steels and non-ferrous alloys as well as in materials refining, alloying with special additives

Depth Profile of Impurity Phase in Wide-Bandgap Cu(In1-x ,Ga x )Se2 Film Fabricated by Three-Stage Process

Science.gov (United States)

Wang, Shenghao; Nazuka, Takehiro; Hagiya, Hideki; Takabayashi, Yutaro; Ishizuka, Shogo; Shibata, Hajime; Niki, Shigeru; Islam, Muhammad M.; Akimoto, Katsuhiro; Sakurai, Takeaki

2018-02-01

For copper indium gallium selenide [Cu(In1-x ,Ga x )Se2, CIGS]-based solar cells, defect states or impurity phase always form due to both the multinary compositions of CIGS film and the difficulty of controlling the growth process, especially for high Ga concentration. To further improve device performance, it is important to understand such formation of impurity phase or defect states during fabrication. In the work presented herein, the formation mechanism of impurity phase Cu2-δ Se and its depth profile in CIGS film with high Ga content, in particular CuGaSe2 (i.e., CGS), were investigated by applying different growth conditions (i.e., normal three-stage process and two-cycle three-stage process). The results suggest that impurity phase Cu2-δ Se is distributed nonuniformly in the film because of lack of Ga diffusion. The formed Cu2-δ Se can be removed by etching the as-deposited CGS film with bromine-methanol solution, resulting in improved device performance.

Crystallization of Trehalose in Frozen Solutions and its Phase Behavior during Drying

Energy Technology Data Exchange (ETDEWEB)

Sundaramurthi, Prakash; Patapoff, Thomas W.; Suryanarayanan, Raj (Genentech); (UMM)

2015-02-19

To study the crystallization of trehalose in frozen solutions and to understand the phase transitions during the entire freeze-drying cycle. Aqueous trehalose solution was cooled to -40 C in a custom-designed sample holder. The frozen solution was warmed to -18 C and annealed, and then dried in the sample chamber of the diffractometer. XRD patterns were continuously collected during cooling, annealing and drying. After cooling, hexagonal ice was the only crystalline phase observed. However, upon annealing, crystallization of trehalose dihydrate was evident. Seeding the frozen solution accelerated the solute crystallization. Thus, phase separation of the lyoprotectant was observed in frozen solutions. During drying, dehydration of trehalose dihydrate yielded a substantially amorphous anhydrous trehalose. Crystallization of trehalose, as trehalose dihydrate, was observed in frozen solutions. The dehydration of the crystalline trehalose dihydrate to substantially amorphous anhydrate occurred during drying. Therefore, analyzing the final lyophile will not reveal crystallization of the lyoprotectant during freeze-drying. The lyoprotectant crystallization can only become evident by continuous monitoring of the system during the entire freeze-drying cycle. In light of the phase separation of trehalose in frozen solutions, its ability to serve as a lyoprotectant warrants further investigation.

Influence aqueous solutions on the mechanical behavior of argillaceous rocks

International Nuclear Information System (INIS)

Wakim, J.

2005-12-01

The hydration of the shale with an aqueous solution induces a swelling deformation which plays an important role in the behaviour of the structures excavated in this type of grounds. This deformation is marked by a three-dimensional and anisotropic character and involves several mechanisms like adsorption, osmosis or capillarity. Several researches were dedicated to swelling and were often much debated due to the complexity of the implied phenomena. The goal of this thesis is therefore to contribute to a better understanding of shale swelling when the rock is confined and hydrated with an aqueous solution. The main part of the work accomplished was related to the Lorraine shale and to the Tournemire shale. To characterize swelling and to identify the main governing parameters, it was necessary to start the issue with an experimental approach. Many apparatus were then developed to carry out tests under various conditions of swelling. In order to facilitate the interpretation of the tests and thereafter the modelling of the behaviour, the experimental procedure adopted consisted of studying first the mechanical aspect and then the chemical aspect of swelling. In the mechanical part, swelling was studied by imposing on the sample a mechanical loading while maintaining during the tests the same aqueous solution. The principal parameters which were studied are the effect of the lateral conditions on axial swelling (impeded strain or constant stress) as well as the influence of the axial stress on radial swelling. The anisotropy of swelling was studied by carrying out, for different orientations of the sample, tests of free swelling, impeded swelling and uniaxial swelling. These various mechanical tests allowed to study the three-dimensional anisotropic swelling in all the conditions and to select the most appropriate test to be used in the second phase of the research. The precise analysis performed to explain the mechanisms behind the swelling of an argillaceous rock

The Electroluminescence Mechanism of Solution-Processed TADF Emitter 4CzIPN Doped OLEDs Investigated by Transient Measurements

Directory of Open Access Journals (Sweden)

Peng Wang

2016-10-01

Full Text Available High efficiency, solution-processed, organic light emitting devices (OLEDs, using a thermally-activated delayed fluorescent (TADF emitter, 1,2,3,5-tetrakis(carbazol-9-yl-4,6-dicyanobenzene (4CzIPN, are fabricated, and the transient electroluminescence (EL decay of the device with a structure of [ITO/PEDOT: PSS/4CzIPN 5 wt % doped 4,40-N,N0-dicarbazolylbiphenyl(CBP/bis-4,6-(3,5-di-4-pyridylphenyl-2-methylpyrimidine (B4PyMPM/lithium fluoride (LiF/Al], is systematically studied. The results shed light on the dominant operating mechanism in TADF-based OLEDs. Electroluminescence in the host–guest system is mainly produced from the 4CzIPN emitter, rather than the exciplex host materials.

Considerable improvement in the stability of solution processed small molecule OLED by annealing

Energy Technology Data Exchange (ETDEWEB)

Mao Guilin [Key Laboratory of Photonics Technology for Information, Key Laboratory for Physical Electronics and Devices of the Ministry of Education, School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an, 710049 (China); Wu Zhaoxin, E-mail: zhaoxinwu@mail.xjtu.edu.cn [Key Laboratory of Photonics Technology for Information, Key Laboratory for Physical Electronics and Devices of the Ministry of Education, School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an, 710049 (China); He Qiang [Key Laboratory of Photonics Technology for Information, Key Laboratory for Physical Electronics and Devices of the Ministry of Education, School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an, 710049 (China); Department of UAV, Wuhan Ordnance Noncommissioned Officers Academy, Wuhan, 430075 (China); Jiao Bo; Xu Guojin; Hou Xun [Key Laboratory of Photonics Technology for Information, Key Laboratory for Physical Electronics and Devices of the Ministry of Education, School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an, 710049 (China); Chen Zhijian; Gong Qihuang [State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing, 100871 (China)

2011-06-15

We investigated the annealing effect on solution processed small organic molecule organic films, which were annealed with various conditions. It was found that the densities of the spin-coated (SC) films increased and the surface roughness decreased as the annealing temperature rose. We fabricated corresponding organic light emitting diodes (OLEDs) by spin coating on the same annealing conditions. The solution processed OLEDs show the considerable efficiency and stability, which were prior or equivalent to the vacuum-deposited (VD) counterparts. Our research shows that annealing process plays a key role in prolonging the lifetime of solution processed small molecule OLEDs, and the mechanism for the improvement of the device performance upon annealing was also discussed.

Quantum mechanical computations and spectroscopy: from small rigid molecules in the gas phase to large flexible molecules in solution.

Science.gov (United States)

Barone, Vincenzo; Improta, Roberto; Rega, Nadia

2008-05-01

Interpretation of structural properties and dynamic behavior of molecules in solution is of fundamental importance to understand their stability, chemical reactivity, and catalytic action. While information can be gained, in principle, by a variety of spectroscopic techniques, the interpretation of the rich indirect information that can be inferred from the analysis of experimental spectra is seldom straightforward because of the subtle interplay of several different effects, whose specific role is not easy to separate and evaluate. In such a complex scenario, theoretical studies can be very helpful at two different levels: (i) supporting and complementing experimental results to determine the structure of the target molecule starting from its spectral properties; (ii) dissecting and evaluating the role of different effects in determining the observed spectroscopic properties. This is the reason why computational spectroscopy is rapidly evolving from a highly specialized research field into a versatile and widespread tool for the assignment of experimental spectra and their interpretation in terms of chemical physical effects. In such a situation, it becomes important that both computationally and experimentally oriented chemists are aware that new methodological advances and integrated computational strategies are available, providing reliable estimates of fundamental spectral parameters not only for relatively small molecules in the gas phase but also for large and flexible molecules in condensed phases. In this Account, we review the most significant methodological contributions from our research group in this field, and by exploiting some recent results of their application to the computation of IR, UV-vis, NMR, and EPR spectral parameters, we discuss the microscopic mechanisms underlying solvent and vibrational effects on the spectral parameters. After reporting some recent achievements for the study of excited states by first principle quantum mechanical

Nonvolatile rewritable memory device based on solution-processable graphene/poly(3-hexylthiophene) nanocomposite

Energy Technology Data Exchange (ETDEWEB)

Zhang, Li, E-mail: lizhang9@zzu.edu.cn [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450052 (China); Li, Ye; Shi, Jun [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450052 (China); Shi, Gaoquan [Department of Chemistry, Tsinghua University, Beijing 100084 (China); Cao, Shaokui, E-mail: Caoshaokui@zzu.edu.cn [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450052 (China)

2013-11-01

An electrically bistable device utilizing a nanocomposite of hexadecylamine-functionalized graphene oxide (HDAGO) with poly(3-hexylthiophene) (P3HT) is demonstrated. The device has an ITO/P3HT-HDAGO/Al sandwich structure, in which the composite film of P3HT-HDAGO was prepared by simple solution phase mixing of the exfoliated HDAGO monolayers with P3HT matrix and a spin-coating method. The memory device exhibits typical bistable electrical switching behavior and a nonvolatile rewritable memory effect, with a turn-on voltage of about 1.5 V and an ON/OFF-state current ratio of 10{sup 5}. Under ambient conditions, both the ON and OFF states are stable under a constant voltage stress or a continuous pulse voltage stress at a read voltage of 1 V. The conduction mechanism is deduced from the modeling of the nature of currents in both states, and the electrical switching behavior can be attributed to the electric-field-induced charge transfer between P3HT and HDAGO nanosheets. - Highlights: • Nonvolatile rewritable memory effect in P3HT–graphene composite is demonstrated. • The memory device was fabricated through a simple solution processing technique. • The device shows a remarkable electrical bistable behavior and excellent stability. • Memory mechanism is deduced from the modeling of the currents in both states.

Nonvolatile rewritable memory device based on solution-processable graphene/poly(3-hexylthiophene) nanocomposite

International Nuclear Information System (INIS)

Zhang, Li; Li, Ye; Shi, Jun; Shi, Gaoquan; Cao, Shaokui

2013-01-01

An electrically bistable device utilizing a nanocomposite of hexadecylamine-functionalized graphene oxide (HDAGO) with poly(3-hexylthiophene) (P3HT) is demonstrated. The device has an ITO/P3HT-HDAGO/Al sandwich structure, in which the composite film of P3HT-HDAGO was prepared by simple solution phase mixing of the exfoliated HDAGO monolayers with P3HT matrix and a spin-coating method. The memory device exhibits typical bistable electrical switching behavior and a nonvolatile rewritable memory effect, with a turn-on voltage of about 1.5 V and an ON/OFF-state current ratio of 10 5 . Under ambient conditions, both the ON and OFF states are stable under a constant voltage stress or a continuous pulse voltage stress at a read voltage of 1 V. The conduction mechanism is deduced from the modeling of the nature of currents in both states, and the electrical switching behavior can be attributed to the electric-field-induced charge transfer between P3HT and HDAGO nanosheets. - Highlights: • Nonvolatile rewritable memory effect in P3HT–graphene composite is demonstrated. • The memory device was fabricated through a simple solution processing technique. • The device shows a remarkable electrical bistable behavior and excellent stability. • Memory mechanism is deduced from the modeling of the currents in both states

Early stages of the mechanical alloying of TiC–TiN powder mixtures

International Nuclear Information System (INIS)

Mura, Giovanna; Musu, Elodia; Delogu, Francesco

2013-01-01

The present work focuses on the alloying behavior of TiC–TiN powder mixtures submitted to mechanical processing by ball milling. Accurate X-ray diffraction analyses indicate a progressive modification of the unit cell parameters of the TiC and TiN phases, suggesting the formation of TiC- and TiN-rich solid solutions with an increasingly larger content of solutes. Once the discrete character of the mechanical treatment is taken into due account, the smooth change of the unit cell parameters can be explained by a sequence of mutual dissolution stages related to individual collisions. At each collision, the average chemical composition of small amounts of TiC- and TiN-rich phases changes discontinuously. The discontinuous changes can be tentatively ascribed to local mass transport processes activated by the mechanical deformation of powders at collisions. -- Highlights: ► Mechanically processed TiC–TiN powder mixtures form two solid solutions. ► An analytical model was developed to describe the mechanical alloying kinetics. ► The amount of powder alloyed at collision was indirectly estimated. ► A few nanomoles of material participate in the alloying process at each collision. ► The chemical composition of the solid solutions was shown to change discontinuously.

Formation, transformation and dissolution of phases formed on surfaces

International Nuclear Information System (INIS)

Shoesmith, D.W.

1983-03-01

The basic mechanisms of film growth, transformation, and dissolution of phases formed on surfaces are discussed. Film growth can occur via solid-state processes or via substrate (usally metal or alloy) dissolution, followed by local supersaturation and precipitation of an insoluble phase. The phase(s) formed may be metastable and transform to a more stable phase, via either solid-state or dissolution-reprecipitation processes. Film dissolution reactions can also occur via a variety of mechanisms, including: (i) direct chemical dissolution when no oxidation state change occurs; (ii) redox dissolution when the film dissolves via a redox reaction involving a reducing or oxidizing agent in solution; and (iii) autoreduction, where film dissolution is coupled to metal dissolution. Such film-growth and dissolution processes, which often produce complex multilayer films, are common in the nuclear industry. A number of examples are discussed

Detection of various phases in liquids from the hypersound velocity and damping near closed phase-separation regions of solutions

International Nuclear Information System (INIS)

Kovalenko, K. V.; Krivokhizha, S. V.; Chaban, I. A.; Chaikov, L. L.

2008-01-01

Theoretical analysis revealed that experimental results obtained in our studies on hypersound propagation in a guaiacol-glycerol solution in the vicinity of the closed phase-separation region, double critical point, and special point, as well as the origin of these regions, can be explained by the presence of two different phases (I and II) of the solution with phase-transition temperature T 0 . Temperature T 0 coincides with the temperature at the center of closed phase-separation regions, as well as with the double critical point and with the special point. In (Frenkel) phase I, molecules are in potential wells whose depth exceeds the thermal energy of a molecule, while thermal energy in (gaslike) phase II is higher than the potential well depth. At the lower critical point, the thermodynamic potential of phase I is equal to the thermodynamic potential of the phase-separated solution. At the upper critical point, the thermodynamic potential of phase II is equal to the thermodynamic potential of the phase-separated solution. The observed broad dome of the hypersound absorption coefficient near T 0 can be explained by the contribution associated with fluctuations of the order parameter corresponding to the transition from phase I to phase II. The difference in the temperature coefficients of hypersound velocity on different sides of T 0 and some other effects are also explained

Solution-Processing of Organic Solar Cells: From In Situ Investigation to Scalable Manufacturing

KAUST Repository

Abdelsamie, Maged

2016-12-05

Photovoltaics provide a feasible route to fulfilling the substantial increase in demand for energy worldwide. Solution processable organic photovoltaics (OPVs) have attracted attention in the last decade because of the promise of low-cost manufacturing of sufficiently efficient devices at high throughput on large-area rigid or flexible substrates with potentially low energy and carbon footprints. In OPVs, the photoactive layer is made of a bulk heterojunction (BHJ) layer and is typically composed of a blend of an electron-donating (D) and an electron-accepting (A) materials which phase separate at the nanoscale and form a heterojunction at the D-A interface that plays a crucial role in the generation of charges. Despite the tremendous progress that has been made in increasing the efficiency of organic photovoltaics over the last few years, with power conversion efficiency increasing from 8% to 13% over the duration of this PhD dissertation, there have been numerous debates on the mechanisms of formation of the crucial BHJ layer and few clues about how to successfully transfer these lessons to scalable processes. This stems in large part from a lack of understanding of how BHJ layers form from solution. This lack of understanding makes it challenging to design BHJs and to control their formation in laboratory-based processes, such as spin-coating, let alone their successful transfer to scalable processes required for the manufacturing of organic solar cells. Consequently, the OPV community has in recent years sought out to better understand the key characteristics of state of the art lab-based organic solar cells and made efforts to shed light on how the BHJ forms in laboratory-based processes as well as in scalable processes. We take the view that understanding the formation of the solution-processed bulk heterojunction (BHJ) photoactive layer, where crucial photovoltaic processes take place, is the one of the most crucial steps to developing strategies towards the

Excited-state dynamics of a ruthenium(II) catalyst studied by transient photofragmentation in gas phase and transient absorption in solution

Energy Technology Data Exchange (ETDEWEB)

Imanbaew, D.; Nosenko, Y. [Fachbereich Chemie, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 52–54, 67663 Kaiserslautern (Germany); Forschungszentrum OPTIMAS, Erwin-Schrödinger-Str. 46, 67663 Kaiserslautern (Germany); Kerner, C. [Fachbereich Chemie, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 52–54, 67663 Kaiserslautern (Germany); Chevalier, K.; Rupp, F. [Fachbereich Physik, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 46, 67663 Kaiserslautern (Germany); Riehn, C., E-mail: riehn@chemie.uni-kl.de [Fachbereich Chemie, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 52–54, 67663 Kaiserslautern (Germany); Forschungszentrum OPTIMAS, Erwin-Schrödinger-Str. 46, 67663 Kaiserslautern (Germany); Thiel, W.R. [Fachbereich Chemie, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 52–54, 67663 Kaiserslautern (Germany); Diller, R. [Fachbereich Physik, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 46, 67663 Kaiserslautern (Germany)

2014-10-17

Graphical abstract: - Highlights: • Ultrafast dynamics of new Ru(II) catalysts investigated in gas phase and solution. • Catalyst activation (HCl loss) achieved in ion trap by UV photoexcitation. • Electronic relaxation proceeds by IVR and IC followed by ground state dissociation. • No triplet formation in contrast to other Ru-polypyridine complexes. • Solvent prohibits catalyst activation in solution by fast vibrational cooling. - Abstract: We report studies on the excited state dynamics of new ruthenium(II) complexes [(η{sup 6}-cymene)RuCl(apypm)]PF{sub 6} (apypm=2-NR{sub 2}-4-(pyridine-2-yl)-pyrimidine, R=CH{sub 3} (1)/H (2)) which, in their active form [1{sup +}-HCl] and [2{sup +}-HCl], catalyze the transfer hydrogenation of arylalkyl ketones in the absence of a base. The investigations encompass femtosecond pump–probe transient mass spectrometry under isolated conditions and transient absorption spectroscopy in acetonitrile solution, both on the cations [(η{sup 6}-cymene)RuCl(apypm)]{sup +} (1{sup +}, 2{sup +}). Gas phase studies on mass selected ions were performed in an ESI ion trap mass spectrometer by transient photofragmentation, unambiguously proving the formation of the activated catalyst species [1{sup +}-HCl] or [2{sup +}-HCl] after photoexcitation being the only fragmentation channel. The primary excited state dynamics in the gas phase could be fitted to a biexponential decay, yielding time constants of <100 fs and 1–3 ps. Transient absorption spectroscopy performed in acetonitrile solution using femtosecond UV/Vis and IR probe laser pulses revealed additional deactivation processes on longer time scales (∼7–12 ps). However, the formation of the active catalyst species after photoexcitation could not be observed in solution. The results from both studies are compared to former CID investigations and DFT calculations concerning the activation mechanism.

TBP determination in nitric acid solutions from solvent extraction process

International Nuclear Information System (INIS)

Kuada, T.A.; Carvalho, E.I. de; Araujo, I. da C.; Cohen, V.H.

1988-07-01

Heavy organic phases have been observed on some occasions during TBP extraction process. These products, described as red oils, were considered as the main cause for process failures, specially in evaporators and concentrators. In view of safety aspects it is necessary to control organic concentration in product and waste solutions. The proposed method involves the organic removal by chloroform as a first step, followed by purification onto a silica gel column. The results are given from analysing TBP and its degradation product (DBP) by gas chromatography. (author) [pt

Quantum mechanics and dynamics in phase space

International Nuclear Information System (INIS)

Zlatev, I.S.

1979-01-01

Attention is paid to formal similarity of quantum mechanics and classical statistical physics. It is supposed that quantum mechanics can be reformulated by means of the quasiprobabilistic distributions (QPD). The procedure of finding a possible dynamics of representative points in a phase space is described. This procedure would lead to an equation of the Liouville type for the given QPD. It is shown that there is always a dynamics for which the phase volume is preserved and there is another dynamics for which the equations of motion are ''canonical''. It follows from the paper that in terms of the QPD the quantum mechanics is analogous to the classical statistical mechanics and it can be interpreted as statistics of phase points, their motion obeying the canonical equations. The difference consists in the fact that in the classical statistical physics constructed is statistics of points in a phase space which depict real, existing, observable states of the system under consideration. In the quantum mechanics constructed is statistics of points in a phase space which correspond to the ''substrate'' of quantum-mechanical objects which have no any physical sense and cannot be observed separately

Effect of hot-dip galvanizing processes on the microstructure and mechanical properties of 600-MPa hot-dip galvanized dual-phase steel

Science.gov (United States)

Kuang, Chun-fu; Zheng, Zhi-wang; Wang, Min-li; Xu, Quan; Zhang, Shen-gen

2017-12-01

A C-Mn dual-phase steel was soaked at 800°C for 90 s and then either rapidly cooled to 450°C and held for 30 s (process A) or rapidly cooled to 350°C and then reheated to 450°C (process B) to simulate the hot-dip galvanizing process. The influence of the hot-dip galvanizing process on the microstructure and mechanical properties of 600-MPa hot-dip galvanized dual-phase steel (DP600) was investigated using optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and tensile tests. The results showed that, in the case of process A, the microstructure of DP600 was composed of ferrite, martensite, and a small amount of bainite. The granular bainite was formed in the hot-dip galvanizing stage, and martensite islands were formed in the final cooling stage after hot-dip galvanizing. By contrast, in the case of process B, the microstructure of the DP600 was composed of ferrite, martensite, bainite, and cementite. In addition, compared with the yield strength (YS) of the DP600 annealed by process A, that for the DP600 annealed by process B increased by approximately 50 MPa because of the tempering of the martensite formed during rapid cooling. The work-hardening coefficient ( n value) of the DP600 steel annealed by process B clearly decreased because the increase of the YS affected the computation result for the n value. However, the ultimate tensile strength (UTS) and elongation ( A 80) of the DP600 annealed by process B exhibited less variation compared with those of the DP600 annealed by process A. Therefore, DP600 with excellent comprehensive mechanical properties (YS = 362 MPa, UTS = 638 MPa, A 80 = 24.3%, n = 0.17) was obtained via process A.

Stress corrosion cracking of duplex stainless steels in caustic solutions

Science.gov (United States)

Bhattacharya, Ananya

Duplex stainless steels (DSS) with roughly equal amount of austenite and ferrite phases are being used in industries such as petrochemical, nuclear, pulp and paper mills, de-salination plants, marine environments, and others. However, many DSS grades have been reported to undergo corrosion and stress corrosion cracking in some aggressive environments such as chlorides and sulfide-containing caustic solutions. Although stress corrosion cracking of duplex stainless steels in chloride solution has been investigated and well documented in the literature but the SCC mechanisms for DSS in caustic solutions were not known. Microstructural changes during fabrication processes affect the overall SCC susceptibility of these steels in caustic solutions. Other environmental factors, like pH of the solution, temperature, and resulting electrochemical potential also influence the SCC susceptibility of duplex stainless steels. In this study, the role of material and environmental parameters on corrosion and stress corrosion cracking of duplex stainless steels in caustic solutions were investigated. Changes in the DSS microstructure by different annealing and aging treatments were characterized in terms of changes in the ratio of austenite and ferrite phases, phase morphology and intermetallic precipitation using optical micrography, SEM, EDS, XRD, nano-indentation and microhardness methods. These samples were then tested for general and localized corrosion susceptibility and SCC to understand the underlying mechanisms of crack initiation and propagation in DSS in the above-mentioned environments. Results showed that the austenite phase in the DSS is more susceptible to crack initiation and propagation in caustic solutions, which is different from that in the low pH chloride environment where the ferrite phase is the more susceptible phase. This study also showed that microstructural changes in duplex stainless steels due to different heat treatments could affect their SCC

Similarities and Differences in Mechanical Alloying Processes of V-Si-B and Mo-Si-B Powders

Directory of Open Access Journals (Sweden)

Manja Krüger

2016-10-01

Full Text Available V-Si-B and Mo-Si-B alloys are currently the focus of materials research due to their excellent high temperature capabilities. To optimize the mechanical alloying (MA process for these materials, we compare microstructures, morphology and particles size as well as hardness evolution during the milling process for the model alloys V-9Si-13B and Mo-9Si-8B. A variation of the rotational speed of the planetary ball mill and the type of grinding materials is therefore investigated. These modifications result in different impact energies during ball-powder-wall collisions, which are quantitatively described in this comparative study. Processing with tungsten carbide vials and balls provides slightly improved impact energies compared to vials and balls made of steel. However, contamination of the mechanically alloyed powders with flaked particles of tungsten carbide is unavoidable. In the case of using steel grinding materials, Fe contaminations are also detectable, which are solved in the V and Mo solid solution phases, respectively. Typical mechanisms that occur during the MA process such as fracturing and comminution are analyzed using the comminution rate KP. In both alloys, the welding processes are more pronounced compared to the fracturing processes.

Ion-Exchange Processes and Mechanisms in Glasses

International Nuclear Information System (INIS)

McGrail, B.P.; Icenhower, J.P.; Darab, J.G.; Shuh, D.K.; Baer, D.R.; Shutthanandan, V.; Thevuthasan, S.; Engelhard, M.H.; Steele, J.L.; Rodriguez, E.A.; Liu, P.; Ivanov, K.E.; Booth, C.H.; Nachimuthu, P.

2001-01-01

Leaching of alkalis from glass is widely recognized as an important mechanism in the initial stages of glass-water interactions. Pioneering experimental studies [1-3] nearly thirty-five years ago established that alkali (designated as M + ) are lost to solution more rapidly than network-forming cations. The overall chemical reaction describing the process can be written as: (triple b ond)Si-O-M + H + → (triple b ond)Si-OH + M + (1) or (triple b ond)Si-O-M + H 3 O + → (triple b ond)Si-OH + M + + H 2 O. (2) Doremus and coworkers [4-7] fashioned a quantitative model where M + ions in the glass are exchanged for counter-diffusing H 3 O + or H + . Subsequent investigations [8], which have relied heavily on reaction layer analysis, recognized the role of H 2 O molecules in the alkali-exchange process, without minimizing the importance of charged hydrogen species. Beginning in the 1980s, however, interest in M + -H + exchange reactions in silicate glasses diminished considerably because important experimental observations showed that network hydrolysis and dissolution rates were principally controlled by the chemical potential difference between the glass and solution (chemical affinity) [9]. For nuclear waste glasses, formation of alteration products or secondary phases that remove important elements from solution, particularly Si, was found to have very large impacts on glass dissolution rates [10,11]. Consequently, recent work on glass/water interactions has focused on understanding this process and incorporating it into models [12]. The ion-exchange process has been largely ignored because it has been thought to be a short duration, secondary or tertiary process that had little or no bearing on long-term corrosion or radionuclide release rates from glasses [13]. The only significant effect identified in the literature that is attributed to alkali ion exchange is an increase in solution pH in static laboratory tests conducted at high surface area-to-volume ratios

Processing of fine-grained W materials without detrimental phases and their mechanical properties at 200-432 K

Energy Technology Data Exchange (ETDEWEB)

Ishijima, Y.; Kannari, S. [International Research Center for Nuclear Materials Science, Institute for Materials Research (IMR), Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Kurishita, H. [International Research Center for Nuclear Materials Science, Institute for Materials Research (IMR), Tohoku University, Oarai, Ibaraki 311-1313 (Japan)], E-mail: kurishi@imr.tohoku.ac.jp; Hasegawa, M. [International Research Center for Nuclear Materials Science, Institute for Materials Research (IMR), Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Hiraoka, Y. [Department of Applied Physics, Okayama University of Science, 1-1 Ridai-cho, Okayama, Okayama 700-0005 (Japan); Takida, T.; Takebe, K. [A.L.M.T. TECH Inc., 2 Iwasekoshi-machi, Toyama, Toyama 931-8543 (Japan)

2008-01-25

Low-temperature ductility improvements of tungsten (W) materials with microstructures of fine grains and fine transition metal-carbide dispersoids require sufficient reductions for consolidates that are free from detrimental dispersoids of the W{sub 2}C phase. In this paper the cause of the occurrence of the detrimental W{sub 2}C phase is studied and an appropriate processing method for its prevention and nearly full densification of mechanically alloyed powder is shown. By applying the method W-0.3 wt%Ti-0.006 wt%C (W-0.3TiC-0.006C) specimens with a negligible amount of the W{sub 2}C phase and reductions up to 78% were prepared. It is found that W-0.3TiC-0.006C exhibits an appreciable ductility even at room temperature by three-point bend impact tests and static tensile tests, with the ductile-to-brittle transition temperature of around 260 K. The observed ductility is likely due to elongated, very thin grain structures of the material. For further ductility improvements, control of oxygen impurities to suppress decarburization during sintering and assure appropriate amounts of (Ti,W)C dispersoids is required.

Phase segregation in cerium-lanthanum solid solutions

NARCIS (Netherlands)

Belliere, V.; Joorst, G; Stephan, O; de Groot, FMF; Weckhuysen, BM

2006-01-01

Electron energy-loss spectroscopy (EELS) in combination with scanning transmission electron microscopy ( STEM) reveals that the La enrichment at the surface of cerium-lanthanum solid solutions is an averaged effect and that segregation occurs in a mixed oxide phase. This separation occurs within a

Asymmetric simple exclusion process with position-dependent hopping rates: Phase diagram from boundary-layer analysis.

Science.gov (United States)

Mukherji, Sutapa

2018-03-01

In this paper, we study a one-dimensional totally asymmetric simple exclusion process with position-dependent hopping rates. Under open boundary conditions, this system exhibits boundary-induced phase transitions in the steady state. Similarly to totally asymmetric simple exclusion processes with uniform hopping, the phase diagram consists of low-density, high-density, and maximal-current phases. In various phases, the shape of the average particle density profile across the lattice including its boundary-layer parts changes significantly. Using the tools of boundary-layer analysis, we obtain explicit solutions for the density profile in different phases. A detailed analysis of these solutions under different boundary conditions helps us obtain the equations for various phase boundaries. Next, we show how the shape of the entire density profile including the location of the boundary layers can be predicted from the fixed points of the differential equation describing the boundary layers. We discuss this in detail through several examples of density profiles in various phases. The maximal-current phase appears to be an especially interesting phase where the boundary layer flows to a bifurcation point on the fixed-point diagram.

Pharmaceutical Perspective on Opalescence and Liquid-Liquid Phase Separation in Protein Solutions.

Science.gov (United States)

Raut, Ashlesha S; Kalonia, Devendra S

2016-05-02

Opalescence in protein solutions reduces aesthetic appeal of a formulation and can be an indicator of the presence of aggregates or precursor to phase separation in solution signifying reduced product stability. Liquid-liquid phase separation of a protein solution into a protein-rich and a protein-poor phase has been well-documented for globular proteins and recently observed for monoclonal antibody solutions, resulting in physical instability of the formulation. The present review discusses opalescence and liquid-liquid phase separation (LLPS) for therapeutic protein formulations. A brief discussion on theoretical concepts based on thermodynamics, kinetics, and light scattering is presented. This review also discusses theoretical concepts behind intense light scattering in the vicinity of the critical point termed as "critical opalescence". Both opalescence and LLPS are affected by the formulation factors including pH, ionic strength, protein concentration, temperature, and excipients. Literature reports for the effect of these formulation factors on attractive protein-protein interactions in solution as assessed by the second virial coefficient (B2) and the cloud-point temperature (Tcloud) measurements are also presented. The review also highlights pharmaceutical implications of LLPS in protein solutions.

Powder metallurgical processing of equiatomic AlCoCrFeNi high entropy alloy: Microstructure and mechanical properties

Energy Technology Data Exchange (ETDEWEB)

Mohanty, S.; Maity, T.N.; Mukhopadhyay, S. [Department of Materials Science and Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Sarkar, S. [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012 (India); Gurao, N.P. [Department of Materials Science and Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Bhowmick, S. [Hysitron Inc., Eden Prairie, MN 55344 (United States); Biswas, Krishanu, E-mail: kbiswas@iitk.ac.in [Department of Materials Science and Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India)

2017-01-02

Phase formation, microstructural evolution and the mechanical properties of novel multi-component equiatomic AlCoCrFeNi high entropy alloy synthesized by high energy ball milling followed by spark plasma sintering have been reported here. The microstructure of the mechanically alloyed (MA) powder and sintered samples were studied using X-ray diffraction, scanning electron and transmission electron microscopy, whereas the detailed investigation of the mechanical properties of the sintered samples were measured using micro and nano hardness techniques. The fracture toughness measurements were performed by applying single edge V notch beam (SEVNB) technique. The MA powder shows the presence of FCC (τ) and BCC (κ) solid solution phases. Extended ball milling (up to 60 h) does not change the phases present in MA powder. The sintered pellets show phase-separated microstructure consisting of Al-Ni rich L1{sub 2} phase, α′ and tetragonal Cr-Fe-Co based σ phase along with Al-Ni-Co-Fe FCC solid solution phase (ε) for sample sintered from 973 to 1273 K. The experimental evidences indicate that BCC (κ) solid solution undergoes eutectoid transformation during sintering leading to the formation of L1{sub 2} ordered α′ and σ phases, whereas FCC (τ) phase remains unaltered with a slight change in the lattice parameter. The hardness of the sample increases with sintering temperature and a sudden rise in hardness is observed 1173 K. The sample sintered at 1273 K shows the highest hardness of ~8 GPa. The elastic modulus mapping clearly indicates the presence of three phases having elastic moduli of about 300, 220 and 160 GPa. The fracture toughness obtained using SEVNB test shows a maximum value of 3.9 MPa m{sup 1/2}, which is attributed to the presence of brittle nanosized σ phase precipitates. It is proposed that significant increase in the fraction of σ phase precipitates and eutectoid transformation of the τ phase contribute to increase in hardness along with

Structural transitions in the titanium alloy β-CEZ studied by precipitation mechanisms after solution treatment

International Nuclear Information System (INIS)

Angelier, C.; Bechet, J.

1994-01-01

The β-CEZ, a high strength titanium alloy developed for aerospace engine applications, is a α/β near β alloy. A wide variety of phase transformations and attendant nodular, lamellar and mixed microstructures are possible according to thermomechanical treatment conditions. The aim of this present paper is to illustrate the influence of solution treat-ment temperature on equilibrium microstructures and continuous cooling transformations. Solution treatment temperature controls the volume fraction of primary α particles and composition of the β-matrix. Therefore the transformation during continuous cooling from α/β or β field depends on β-matrix stability and potential sites amount of α precipitation. After a β solution treatment, the α particles are disappeared and the β phase contains all alloying elements; the continuous cooling transformation produces a Widmanstaetten structure. If the cooling rate or/and the solution treatment temperature in the α/β field are sufficiently low, the microstructure consists only of nodular morphology. During α particles growth the α volume fraction increases as equilibrium and the decreasing of growth kinetic leads to supersaturated β matrix and Widmanstaetten α precipitation. The final microstructures are mixed. The influence of solution trat-ment temperature and cooling rate on nucleation and growth mechanisms is specially developed. (orig.)

Transport of Liquid Phase Organic Solutes in Liquid Crystalline Membranes

OpenAIRE

Han, Sangil

2010-01-01

Porous cellulose nitrate membranes were impregnated with 8CB and PCH5 LCs (liquid crystals) and separations of solutes dissolved in aqueous phases were performed while monitoring solute concentration via UV-VIS spectrometry. The diffusing organic solutes, which consist of one aromatic ring and various functional groups, were selected to exclude molecular size effects on the diffusion and sorption. We studied the effects on solute transport of solute intra-molecular hydrogen bonding and so...

Enhancement of the electrochemical behaviour and biological performance of Ti–25Ta–5Zr alloy by thermo-mechanical processing

Energy Technology Data Exchange (ETDEWEB)

Cimpean, Anisoara [Department of Biochemistry and Molecular Biology, University of Bucharest, Spl. Independentei, 91-95, 050095 Bucharest (Romania); Vasilescu, Ecaterina; Drob, Paula [Department of Electrochemistry and Corrosion, Institute of Physical Chemistry “Ilie Murgulescu” of Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Cinca, Ion, E-mail: ion_cinca@hotmail.com [Faculty of Material Science and Engineering, Politehnica University, Spl. Independentei 313, 060042 Bucharest (Romania); Vasilescu, Cora; Anastasescu, Mihai [Department of Electrochemistry and Corrosion, Institute of Physical Chemistry “Ilie Murgulescu” of Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Mitran, Valentina [Department of Biochemistry and Molecular Biology, University of Bucharest, Spl. Independentei, 91-95, 050095 Bucharest (Romania); Drob, Silviu Iulian [Department of Electrochemistry and Corrosion, Institute of Physical Chemistry “Ilie Murgulescu” of Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania)

2014-05-01

A new Ti–25Ta–5Zr alloy based only on non-toxic and non-allergic elements was elaborated in as-cast and thermo-mechanical processed, recrystallized states (XRD and SEM) in order to be used as candidate material for implant applications. Its long-term interactions with Ringer–Brown and Ringer solutions of different pH values and its cytocompatibility were determined. The thermo-mechanically processed alloy has nobler electrochemical behaviour than as-cast alloy due to finer microstructure obtained after the applied treatment. Corrosion and ion release rates presented the lowest values for the treated alloy. Nyquist and Bode plots displayed higher impedance values and phase angles for the processed alloy, denoting a more protective passive film. SEM micrographs revealed depositions from solutions that contain calcium, phosphorous and oxygen ions (EDX analysis), namely calcium phosphate. An electric equivalent circuit with two time constants was modelled. Cell culture experiments with MC3T3-E1 pre-osteoblasts demonstrated that thermo-mechanically processed Ti–25Ta–5Zr alloy supports a better cell adhesion and spreading, and enhanced cell proliferation. Altogether, these data indicate that thermo-mechanical treatment endows the alloy with improved anticorrosion and biological performances. - Highlights: • Ti–25Ta–5Zr alloy exhibited noble electrochemical, passive behaviour in simulated biofluids. • An electric equivalent circuit with two time constants was modelled. • Corrosion rates show the lowest values for the recrystallized Ti–25Ta–5Zr alloy. • In vitro tests revealed good cytocompatibility of as-cast and processed alloy. • Recrystallized treatment endows the alloy with superior biological performances.

Enhancement of the electrochemical behaviour and biological performance of Ti–25Ta–5Zr alloy by thermo-mechanical processing

International Nuclear Information System (INIS)

Cimpean, Anisoara; Vasilescu, Ecaterina; Drob, Paula; Cinca, Ion; Vasilescu, Cora; Anastasescu, Mihai; Mitran, Valentina; Drob, Silviu Iulian

2014-01-01

A new Ti–25Ta–5Zr alloy based only on non-toxic and non-allergic elements was elaborated in as-cast and thermo-mechanical processed, recrystallized states (XRD and SEM) in order to be used as candidate material for implant applications. Its long-term interactions with Ringer–Brown and Ringer solutions of different pH values and its cytocompatibility were determined. The thermo-mechanically processed alloy has nobler electrochemical behaviour than as-cast alloy due to finer microstructure obtained after the applied treatment. Corrosion and ion release rates presented the lowest values for the treated alloy. Nyquist and Bode plots displayed higher impedance values and phase angles for the processed alloy, denoting a more protective passive film. SEM micrographs revealed depositions from solutions that contain calcium, phosphorous and oxygen ions (EDX analysis), namely calcium phosphate. An electric equivalent circuit with two time constants was modelled. Cell culture experiments with MC3T3-E1 pre-osteoblasts demonstrated that thermo-mechanically processed Ti–25Ta–5Zr alloy supports a better cell adhesion and spreading, and enhanced cell proliferation. Altogether, these data indicate that thermo-mechanical treatment endows the alloy with improved anticorrosion and biological performances. - Highlights: • Ti–25Ta–5Zr alloy exhibited noble electrochemical, passive behaviour in simulated biofluids. • An electric equivalent circuit with two time constants was modelled. • Corrosion rates show the lowest values for the recrystallized Ti–25Ta–5Zr alloy. • In vitro tests revealed good cytocompatibility of as-cast and processed alloy. • Recrystallized treatment endows the alloy with superior biological performances

Silicon Nano fabrication by Atomic Force Microscopy-Based Mechanical Processing

International Nuclear Information System (INIS)

Miyake, Sh.; Wang, M.; Kim, J.

2014-01-01

This paper reviews silicon nano fabrication processes using atomic force microscopy (AFM). In particular, it summarizes recent results obtained in our research group regarding AFM-based silicon nano fabrication through mechanochemical local oxidation by diamond tip sliding, as well as mechanical, electrical, and electromechanical processing using an electrically conductive diamond tip. Microscopic three-dimensional manufacturing mainly relies on etching, deposition, and lithography. Therefore, a special emphasis was placed on nano mechanical processes, mechanochemical reaction by potassium hydroxide solution etching, and mechanical and electrical approaches. Several important surface characterization techniques consisting of scanning tunneling microscopy and related techniques, such as scanning probe microscopy and AFM, were also discussed.

Processing of radioactive waste solutions in a vacuum evaporator-crystallizer

International Nuclear Information System (INIS)

Petrie, J.C.; Donovan, R.I.; Van der Cook, R.E.; Christensen, W.R.

1975-01-01

Results of the first 18 months' operation of Hanford's vacuum evaporator-crystallizer are reported. This process reduces the volume of radioactive waste solutions and simultaneously converts the waste to a less mobile salt cake. The evaporator-crystallizer is operating at better than design production rates and has reduced the volume of radioactive wastes by more than 15 million gallons. A process description, plant performance data, mechanical difficulties, and future operating plans are discussed. Also discussed is a computer model of the evaporator-crystallizer process

Bunsen Reaction using a HIx Solution (HI-I2-H2O with Countercurrent Flow for Sulfur-Iodine Hydrogen Production Process

Directory of Open Access Journals (Sweden)

Kim Hyo-Sub

2016-01-01

Full Text Available In the sulfur-iodine hydrogen production process, the Bunsen reaction is a crucial section because of the linkage with the H2SO4 and HI decomposition sections. The HIx solution (HI-I2-H2O mixture was fed to the Bunsen reaction section as a reactant from the HI decomposition section. In this study, the Bunsen reaction using the HIx solution with countercurrent flow was performed. The production rate of HIx phase solution increased while that of H2SO4 phase solution was maintained constant when increasing the flow rate of HIx solution. As the SO2 flow rate increased, the production rates of H2SO4 and HIx phase solutions increased. The amount of resultant H2SO4 phase was very lower than that of resultant HIx phase under the conditions examined in this study.

Lower critical solution temperature (LCST) phase separation of glycol ethers for forward osmotic control.

Science.gov (United States)

Nakayama, Daichi; Mok, Yeongbong; Noh, Minwoo; Park, Jeongseon; Kang, Sunyoung; Lee, Yan

2014-03-21

Lower critical solution temperature (LCST) phase transition of glycol ether (GE)-water mixtures induces an abrupt change in osmotic pressure driven by a mild temperature change. The temperature-controlled osmotic change was applied for the forward osmosis (FO) desalination. Among three GEs evaluated, di(ethylene glycol) n-hexyl ether (DEH) was selected as a potential FO draw solute. A DEH-water mixture with a high osmotic pressure could draw fresh water from a high-salt feed solution such as seawater through a semipermeable membrane at around 10 °C. The water-drawn DEH-water mixture was phase-separated into a water-rich phase and a DEH-rich phase at around 30 °C. The water-rich phase with a much reduced osmotic pressure released water into a low-salt solution, and the DEH-rich phase was recovered into the initial DEH-water mixture. The phase separation behaviour, the residual GE concentration in the water-rich phase, the osmotic pressure of the DEH-water mixture, and the osmotic flux between the DEH-water mixture and salt solutions were carefully analysed for FO desalination. The liquid-liquid phase separation of the GE-water mixture driven by the mild temperature change between 10 °C and 30 °C is very attractive for the development of an ideal draw solute for future practical FO desalination.

Pinning of phase separation of aqueous solution of hydroxypropylmethylcellulose by gelation

Science.gov (United States)

Kita, Rio; Kaku, Takeshi; Kubota, Kenji; Dobashi, Toshiaki

1999-08-01

Opalescence of the aqueous solution of hydroxypropylmethylcellulose (HPMC) induced by heating has been studied in terms of the phase diagram and the phase separation dynamics. The cloud point curve and the sol-to-gel transition curve intersected with each other at about 55 °C. Just above the cloud-point curve at which the spinodal curve has its minimum, a ring-like scattering pattern appeared corresponding to the spinodal decomposition. Temporal growth of the scattering function in the course of phase separation was studied by a time-resolved light scattering technique. The gelation pinned the phase separation (spinodal decomposition) of the aqueous HPMC solution.

Early stages of the mechanical alloying of TiC-TiN powder mixtures

Energy Technology Data Exchange (ETDEWEB)

Mura, Giovanna [Dipartimento di Ingegneria Elettrica ed Elettronica, Universita degli Studi di Cagliari, via Marengo 2, 09123 Cagliari (Italy); Musu, Elodia [Industrial Telemicroscopy Laboratory, Sardegna Ricerche, Polaris, Technology Park of Sardinia, Edificio 3, Loc. Piscinamanna, 09010 Pula (Italy); Delogu, Francesco, E-mail: francesco.delogu@dimcm.unica.it [Dipartimento di Ingegneria Meccanica, Chimica, e dei Materiali, Universita degli Studi di Cagliari, via Marengo 2, I-09123 Cagliari (Italy)

2013-01-15

The present work focuses on the alloying behavior of TiC-TiN powder mixtures submitted to mechanical processing by ball milling. Accurate X-ray diffraction analyses indicate a progressive modification of the unit cell parameters of the TiC and TiN phases, suggesting the formation of TiC- and TiN-rich solid solutions with an increasingly larger content of solutes. Once the discrete character of the mechanical treatment is taken into due account, the smooth change of the unit cell parameters can be explained by a sequence of mutual dissolution stages related to individual collisions. At each collision, the average chemical composition of small amounts of TiC- and TiN-rich phases changes discontinuously. The discontinuous changes can be tentatively ascribed to local mass transport processes activated by the mechanical deformation of powders at collisions. -- Highlights: Black-Right-Pointing-Pointer Mechanically processed TiC-TiN powder mixtures form two solid solutions. Black-Right-Pointing-Pointer An analytical model was developed to describe the mechanical alloying kinetics. Black-Right-Pointing-Pointer The amount of powder alloyed at collision was indirectly estimated. Black-Right-Pointing-Pointer A few nanomoles of material participate in the alloying process at each collision. Black-Right-Pointing-Pointer The chemical composition of the solid solutions was shown to change discontinuously.

Rapid formation of phase-clean 110 K (Bi-2223) powders derived via freeze-drying process

Science.gov (United States)

Balachandran, U.

1996-06-04

A process for the preparation of amorphous precursor powders for Pb-doped Bi{sub 2}Sr{sub 2} Ca{sub 2}Cu{sub 3}O{sub x} (2223) includes a freeze-drying process incorporating a splat-freezing step. The process generally includes splat freezing a nitrate solution of Bi, Pb, Sr, Ca, and Cu to form flakes of the solution without any phase separation; grinding the frozen flakes to form a powder; freeze-drying the frozen powder; heating the dried powder to form a dry green precursor powders; denitrating the green-powders; heating the denitrated powders to form phase-clean Bi-2223 powders. The grain boundaries of the 2223 grains appear to be clean, leading to good intergrain contact between 2223 grains. 11 figs.

Thermal Mechanical Processing Effects on Microstructure Evolution and Mechanical Properties of the Sintered Ti-22Al-25Nb Alloy.

Science.gov (United States)

Wang, Yuanxin; Lu, Zhen; Zhang, Kaifeng; Zhang, Dalin

2016-03-11

This work illustrates the effect of thermal mechanical processing parameters on the microstructure and mechanical properties of the Ti-22Al-25Nb alloy prepared by reactive sintering with element powders, consisting of O, B2 and Ti₃Al phases. Tensile and plane strain fracture toughness tests were carried out at room temperature to understand the mechanical behavior of the alloys and its correlation with the microstructural features characterized by scanning and transmission electron microscopy. The results show that the increased tensile strength (from 340 to 500 MPa) and elongation (from 3.6% to 4.2%) is due to the presence of lamellar O/B2 colony and needle-like O phase in B2 matrix in the as-processed Ti-22Al-25Nb alloys, as compared to the coarse lath O adjacent to B2 in the sintered alloys. Changes in morphologies of O phase improve the fracture toughness ( K IC ) of the sintered alloys from 7 to 15 MPa·m -1/2 . Additionally, the fracture mechanism shifts from cleavage fracture in the as-sintered alloys to quasi-cleavage fracture in the as-processed alloys.

Liquid-phase and vapor-phase dehydration of organic/water solutions

Science.gov (United States)

Huang, Yu [Palo Alto, CA; Ly, Jennifer [San Jose, CA; Aldajani, Tiem [San Jose, CA; Baker, Richard W [Palo Alto, CA

2011-08-23

Processes for dehydrating an organic/water solution by pervaporation or vapor separation using fluorinated membranes. The processes are particularly useful for treating mixtures containing light organic components, such as ethanol, isopropanol or acetic acid.

Analysis of benzoquinone decomposition in solution plasma process

International Nuclear Information System (INIS)

Bratescu, M.A.; Saito, N.

2016-01-01

The decomposition of p-benzoquinone (p-BQ) in Solution Plasma Processing (SPP) was analyzed by Coherent Anti-Stokes Raman Spectroscopy (CARS) by monitoring the change of the anti-Stokes signal intensity of the vibrational transitions of the molecule, during and after SPP. Just in the beginning of the SPP treatment, the CARS signal intensities of the ring vibrational molecular transitions increased under the influence of the electric field of plasma. The results show that plasma influences the p-BQ molecules in two ways: (i) plasma produces a polarization and an orientation of the molecules in the local electric field of plasma and (ii) the gas phase plasma supplies, in the liquid phase, hydrogen and hydroxyl radicals, which reduce or oxidize the molecules, respectively, generating different carboxylic acids. The decomposition of p-BQ after SPP was confirmed by UV-visible absorption spectroscopy and liquid chromatography

Analysis of benzoquinone decomposition in solution plasma process

Science.gov (United States)

Bratescu, M. A.; Saito, N.

2016-01-01

The decomposition of p-benzoquinone (p-BQ) in Solution Plasma Processing (SPP) was analyzed by Coherent Anti-Stokes Raman Spectroscopy (CARS) by monitoring the change of the anti-Stokes signal intensity of the vibrational transitions of the molecule, during and after SPP. Just in the beginning of the SPP treatment, the CARS signal intensities of the ring vibrational molecular transitions increased under the influence of the electric field of plasma. The results show that plasma influences the p-BQ molecules in two ways: (i) plasma produces a polarization and an orientation of the molecules in the local electric field of plasma and (ii) the gas phase plasma supplies, in the liquid phase, hydrogen and hydroxyl radicals, which reduce or oxidize the molecules, respectively, generating different carboxylic acids. The decomposition of p-BQ after SPP was confirmed by UV-visible absorption spectroscopy and liquid chromatography.

Crystalline-to-amorphous phase transformation in mechanically alloyed Fe50W50 powders

International Nuclear Information System (INIS)

Sherif El-Eskandarany, M.S.; Sumiyama, K.; Suzuki, K.

1997-01-01

A mechanical alloying process via a ball milling technique has been applied for preparing amorphous Fe 50 W 50 alloy powders. The results have shown that during the first and second stages of milling (0 to 360 ks) W atoms emigrate to Fe lattices to form nanocrystalline b.c.c. Fe-W solid solution, with a grain size of about 7 nm in diameter. After 720 ks of the milling time, this solid solution was transformed to an amorphous Fe-W alloy coexisting with the residual fraction of the unprocessed W powders. During the last stage of milling (720 to 1,440 ks) all of this residual W powder reacts with the amorphous phase to form a homogeneous Fe 50 W 50 amorphous alloy. The crystallization temperature and the enthalpy change of crystallization of amorphous Fe 50 W 50 powders milled for 1,440 ks were measured to be 860 K and -9kJ/mol, respectively. The amorphous Fe 50 W 50 powder produced is almost paramagnetic at room temperature. The powder comprises homogeneous and smooth spheres with an average size of about 0.5 microm in diameter

Glycine phases formed from frozen aqueous solutions: Revisited

Energy Technology Data Exchange (ETDEWEB)

Surovtsev, N. V. [Institute of Automation and Electrometry, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Adichtchev, S. V.; Malinovsky, V. K. [Institute of Automation and Electrometry, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation); Ogienko, A. G.; Manakov, A. Yu. [Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation); Drebushchak, V. A. [Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Institute of Geology and Mineralogy, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation); Ancharov, A. I.; Boldyreva, E. V. [Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Institute of Solid Chemistry and Mechanochemistry, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation); Yunoshev, A. S. [Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Lavrentiev Institute of Hydrodynamics, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation)

2012-08-14

Glycine phases formed when aqueous solutions were frozen and subsequently heated under different conditions were studied by Raman scattering, x-ray diffraction, and differential scanning calorimetry (DSC) techniques. Crystallization of ice I{sub h} was observed in all the cases. On cooling at the rates of 0.5 K/min and 5 K/min, glassy glycine was formed as an intermediate phase which lived about 1 min or less only, and then transformed into {beta}-polymorph of glycine. Quench cooling of glycine solutions (15% w/w) in liquid nitrogen resulted in the formation of a mixture of crystalline water ice I{sub h} and a glassy glycine, which could be preserved at cryogenic temperatures (80 K) for an indefinitely long time. This mixture remained also quite stable for some time after heating above the cryogenic temperature. Subsequent heating under various conditions resulted in the transformation of the glycine glass into an unknown crystalline phase (glycine 'X-phase') at 209-216 K, which at 218-226 K transformed into {beta}-polymorph of glycine. The 'X-phase' was characterized by Raman spectroscopy; it could be obtained in noticeable amounts using a special preparation technique and tentatively characterized by x-ray powder diffraction (P2, a= 6.648 A, b= 25.867 A, c= 5.610 A, {beta}= 113.12 Masculine-Ordinal-Indicator ); the formation of 'X-phase' from the glycine glassy phase and its transformation into {beta}-polymorph were followed by DSC. Raman scattering technique with its power for unambiguous identification of the crystalline and glassy polymorphs without limitation on the crystallite size helped us to follow the phase transformations during quenching, heating, and annealing. The experimental findings are considered in relation to the problem of control of glycine polymorphism on crystallization.

Glycine phases formed from frozen aqueous solutions: Revisited

Science.gov (United States)

Surovtsev, N. V.; Adichtchev, S. V.; Malinovsky, V. K.; Ogienko, A. G.; Drebushchak, V. A.; Manakov, A. Yu.; Ancharov, A. I.; Yunoshev, A. S.; Boldyreva, E. V.

2012-08-01

Glycine phases formed when aqueous solutions were frozen and subsequently heated under different conditions were studied by Raman scattering, x-ray diffraction, and differential scanning calorimetry (DSC) techniques. Crystallization of ice Ih was observed in all the cases. On cooling at the rates of 0.5 K/min and 5 K/min, glassy glycine was formed as an intermediate phase which lived about 1 min or less only, and then transformed into β-polymorph of glycine. Quench cooling of glycine solutions (15% w/w) in liquid nitrogen resulted in the formation of a mixture of crystalline water ice Ih and a glassy glycine, which could be preserved at cryogenic temperatures (80 K) for an indefinitely long time. This mixture remained also quite stable for some time after heating above the cryogenic temperature. Subsequent heating under various conditions resulted in the transformation of the glycine glass into an unknown crystalline phase (glycine "X-phase") at 209-216 K, which at 218-226 K transformed into β-polymorph of glycine. The "X-phase" was characterized by Raman spectroscopy; it could be obtained in noticeable amounts using a special preparation technique and tentatively characterized by x-ray powder diffraction (P2, a = 6.648 Å, b = 25.867 Å, c = 5.610 Å, β = 113.12°); the formation of "X-phase" from the glycine glassy phase and its transformation into β-polymorph were followed by DSC. Raman scattering technique with its power for unambiguous identification of the crystalline and glassy polymorphs without limitation on the crystallite size helped us to follow the phase transformations during quenching, heating, and annealing. The experimental findings are considered in relation to the problem of control of glycine polymorphism on crystallization.

Business Process Reengineering, a Crisis Solution or a Necessity

Directory of Open Access Journals (Sweden)

Gabriela GHEORGHE

2012-08-01

Full Text Available This case study shows that the company decided to implement Business Process Reengineering (BPR not only because external environment had changed, but also due to its obsolete business processes and organizational structure. The article will highlight the importance of the organizations' focusing on sub-goals, in order to finally reach the desired result in the organization's main goals. When rapid evolution has become the fundamental contemporary coordinate, reengineering is a form of company innovative reaction in terms of intensifying competition and globalization. Remodeling the Company in phases of crisis, when time pressure reduces the type and number of solutions that can be adopted, without effective leadership, can lead in most cases to failure. The effect of redesigning the business processes depends on how well it is implemented, coordinated and monitored.

Business Process Reengineering, a Crises Solution or a Necessity

Directory of Open Access Journals (Sweden)

Gabriela GHEORGHE

2011-11-01

Full Text Available This case study shows that the company decided to implement Business Process Reengineering (BPR not only because external environment had changed, but also due to its obsolete business processes and organizational structure. The article will highlight the importance of the organizations' focusing on sub-goals, in order to finally reach the desired result in the organization's main goals. When rapid evolution has become the fundamental contemporary coordinate, reengineering is a form of company innovative reaction in terms of intensifying competition and globalization. Remodelling the Company in phases of crisis, when time pressure reduces the type and number of solutions that can be adopted, without effective leadership can lead in most cases to failure. The effect of redesigning the business processes depends on how well it is implemented, coordinated and monitored.

Phase transitions of single polymer chains and of polymer solutions: insights from Monte Carlo simulations

International Nuclear Information System (INIS)

Binder, K; Paul, W; Strauch, T; Rampf, F; Ivanov, V; Luettmer-Strathmann, J

2008-01-01

The statistical mechanics of flexible and semiflexible macromolecules is distinct from that of small molecule systems, since the thermodynamic limit can also be approached when the number of (effective) monomers of a single chain (realizable by a polymer solution in the dilute limit) is approaching infinity. One can introduce effective attractive interactions into a simulation model for a single chain such that a swollen coil contracts when the temperature is reduced, until excluded volume interactions are effectively canceled by attractive forces, and the chain conformation becomes almost Gaussian at the theta point. This state corresponds to a tricritical point, as the renormalization group theory shows. Below the theta temperature a fluid globule is predicted (at nonzero concentration then phase separation between dilute and semidilute solutions occurs), while at still lower temperature a transition to a solid phase (crystal or glass) occurs. Monte Carlo simulations have shown, however, that the fluid globule phase may become suppressed, when the range of the effective attractive forces becomes too short, with the result that a direct (ultimately first-order) transition from the swollen coil to the solid occurs. This behavior is analogous to the behavior of colloidal particles with a very short range of attractive forces, where liquid-vapor-type phase separation may be suppressed. Analogous first-order transitions from swollen coils to dense rodlike or toroidal structures occur for semiflexible polymers. Finally, the modifications of the behavior discussed when the polymers are adsorbed at surfaces are also mentioned, and possible relations to wetting behavior of polymer solutions are addressed.

Formation of Ni(Al, Mo) solid solutions by mechanical alloying and their ordering on heating

International Nuclear Information System (INIS)

Portnoj, V.K.; Tomilin, I.A.; Blinov, A.M.; Kulik, T.

2002-01-01

The Ni(Al, Mo) solid solutions with different crystalline lattice periods (0.3592 and 0.3570 nm correspondingly) are formed in the course of the Ni 70 Al 25 Mo 5 and Ni 75 Al 20 Mo 5 powder mixtures mechanical alloying (MA) (through the mechanical activation in a vibrating mill). After MA the Mo atoms in the Ni 75 Al 20 Mo 5 mixture completely replace the aluminium positions with formation of the Ni 75 (AlMo) 25 (the L1 2 -type) ternary ordered phase, whereby such a distribution remains after heating up to 700 deg C. The Ni(Al, Mo) metastable solution is formed by MA in the Ni 75 Al 20 Mo 5 mixture, which decays with the release of molybdenum and the remained aluminide undergoes ordering by the L1 2 -type [ru

Liquid-solid phase transition of physical hydrogels subject to an externally applied electro-chemo-mechanical coupled field with mobile ionic species.

Science.gov (United States)

Wu, Tao; Li, Hua

2017-08-09

In this study, a model was multiphysically developed for the simulation of the phase transition of physical hydrogels between liquid solution and solid gel states, subject to an electro-chemo-mechanically coupled field, with the effect of the mobile ionic species in the solution. The present model consists of the governing equations for the equilibrium of forces and the conservation of mass, Maxwell's equations, and an evolution equation for the interface. Based on the second law of thermodynamics, the constitutive equations are formulated from the energy viewpoint, including a novel formulation of free energy with the effect of crosslink density. The present model may be reduced to Suo's non-equilibrium thermodynamic theory if the interface is ignored when only a single phase exists. It may also be reduced to Dolbow's model for gel-gel phase transition when the electric field is ignored. Therefore, the present model becomes more generalized since it is able to represent both the bulk phase and the interface behaviors, and the mechanical field is simultaneously coupled with both the electric and chemical fields. In the first case study, the system at equilibrium state was numerically investigated for analysis of the influences of the electrical and chemical potentials as well as the mechanical pressure externally imposed on the boundary of the system domain. The second case study presents a spherically symmetrical solution-gel phase transition at non-equilibrium states, with the emphasis on the evolution of both the interface and electrochemical potentials.

The mechanism of 'solid-body' rotation of superfluid and normal components in the process of separation into layers of the over saturated 3He-4He solution

International Nuclear Information System (INIS)

Pashitskij, Eh.A.; Mal'nev, V.N.; Naryshkin, R.A.

2005-01-01

It is shown that unstable hydrodynamic vortices may be formed inside subcritical nuclei of separation in the normal component of the decaying over saturated 3 He- 4 He solution. We consider the mechanism of drag of the superfluid component of the 3 He- 4 He solution by the normal component into the 'solid-body' rotation due to the Hall-Vinen-Bekarevich-Khalatnikov forces in the equations of two-fluid hydrodynamics, resulting in the formation of quantized vortices. An increase in the average density of the quantized vortices may accelerate the process of heterogeneous decomposition of the 3 He- 4 He solution

Controlling solution-phase polymer aggregation with molecular weight and solvent additives to optimize polymer-fullerene bulk heterojunction solar cells

KAUST Repository

Bartelt, Jonathan A.

2014-03-20

The bulk heterojunction (BHJ) solar cell performance of many polymers depends on the polymer molecular weight (M n) and the solvent additive(s) used for solution processing. However, the mechanism that causes these dependencies is not well understood. This work determines how M n and solvent additives affect the performance of BHJ solar cells made with the polymer poly(di(2-ethylhexyloxy)benzo[1,2-b:4,5-b\\']dithiophene-co- octylthieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD). Low M n PBDTTPD devices have exceedingly large fullerene-rich domains, which cause extensive charge-carrier recombination. Increasing the M n of PBDTTPD decreases the size of these domains and significantly improves device performance. PBDTTPD aggregation in solution affects the size of the fullerene-rich domains and this effect is linked to the dependency of PBDTTPD solubility on M n. Due to its poor solubility high M n PBDTTPD quickly forms a fibrillar polymer network during spin-casting and this network acts as a template that prevents large-scale phase separation. Furthermore, processing low M n PBDTTPD devices with a solvent additive improves device performance by inducing polymer aggregation in solution and preventing large fullerene-rich domains from forming. These findings highlight that polymer aggregation in solution plays a significant role in determining the morphology and performance of BHJ solar cells. The performance of poly(di(2-ethylhexyloxy) benzo[1,2-b:4,5-b\\']dithiophene-co-octylthieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) bulk heterojunction solar cells strongly depends on the polymer molecular weight, and processing these bulk heterojunctions with a solvent additive preferentially improves the performance of low molecular weight devices. It is demonstrated that polymer aggregation in solution significantly impacts the thin-film bulk heterojunction morphology and is vital for high device performance. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development studies for a novel wet oxidation process. Phase 2

International Nuclear Information System (INIS)

1994-07-01

DETOX SM is a catalyzed wet oxidation process which destroys organic materials in an acidic water solution of iron at 373 to 473 K. The solution can be used repeatedly to destroy great amounts of organic materials. Since the process is conducted in a contained vessel, air emissions from the process can be well controlled. The solution is also capable of dissolving and concentrating many heavy and radioactive metals for eventual stabilization and disposal. The Phase 2 effort for this project is site selection and engineering design for a DETOX demonstration unit. Site selection was made using a set of site selection criteria and evaluation factors. A survey of mixed wastes at DOE sites was conducted using the Interim Mixed Waste Inventory Report. Sites with likely suitable waste types were identified. Potential demonstration sites were ranked based on waste types, interest, regulatory needs, scheduling, ability to provide support, and available facilities. Engineering design for the demonstration unit is in progress and is being performed by Jacobs Applied Technology. The engineering design proceeded through preliminary process flow diagrams (PFDs), calculation of mass and energy balances for representative waste types, process and instrumentation diagrams (P and IDs), preparation of component specifications, and a firm cost estimate for fabrication of the demonstration unit

Quantum mechanics in coherent algebras on phase space

International Nuclear Information System (INIS)

Lesche, B.; Seligman, T.H.

1986-01-01

Quantum mechanics is formulated on a quantum mechanical phase space. The algebra of observables and states is represented by an algebra of functions on phase space that fulfills a certain coherence condition, expressing the quantum mechanical superposition principle. The trace operation is an integration over phase space. In the case where the canonical variables independently run from -infinity to +infinity the formalism reduces to the representation of quantum mechanics by Wigner distributions. However, the notion of coherent algebras allows to apply the formalism to spaces for which the Wigner mapping is not known. Quantum mechanics of a particle in a plane in polar coordinates is discussed as an example. (author)

A mechanism for the hydrogen uptake process in zirconium alloys

International Nuclear Information System (INIS)

Cox, B.

1999-01-01

Hydrogen uptake data for thin Zircaloy-2 specimens in steam at 300-400 C have been analysed to show that there is a decrease in the rate of uptake with respect to the rate of oxidation when the terminal solid solubility (TSS) of hydrogen in the metal is exceeded. In order for TSS to be reached during pre-transition oxidation a very thin 0.125 mm Zircaloy sheet was used. The specimens had been pickled initially removing all Zr 2 (Fe/Ni) particles from the initial surfaces, yet the initial hydrogen uptake rates were still much higher than for Zircaloy-4 or a binary Zr/Fe alloy that did not contain phases that dissolve readily during pickling. Cathodic polarisation at room temperature in CuSO 4 solution showed that small cracks or pores formed the cathodic sites in pre-transition oxide films. Some were at pits resulting from the initial dissolution of the Zr 2 (Fe/Ni) phase; others were not; none were at the remaining intermetallics in the original surface. These small cracks are thought to provide the ingress routes for hydrogen. A microscopic steam starvation process at the bottoms of these small cracks or pores, leading to the accumulation of hydrogen adjacent to the oxide/metal interface, and causing breakdown of the passive oxide forming at the bottom of the flaw, is thought to provide the mechanism for the hydrogen uptake process during both pre-transition and post-transition oxidation. (orig.)

First-principles study of ternary fcc solution phases from special quasirandom structures

International Nuclear Information System (INIS)

Shin Dongwon; Wang Yi; Liu Zikui; Walle, Axel van de

2007-01-01

In the present work, ternary special quasirandom structures (SQSs) for a fcc solid solution phase are generated at different compositions, x A =x B =x C =(1/3) and x A =(1/2), x B =x C =(1/4), whose correlation functions are satisfactorily close to those of a random fcc solution. The generated SQSs are used to calculate the mixing enthalpy of the fcc phase in the Ca-Sr-Yb system. It is observed that first-principles calculations of all the binary and ternary SQSs in the Ca-Sr-Yb system exhibit very small local relaxation. It is concluded that the fcc ternary SQSs can provide valuable information about the mixing behavior of the fcc ternary solid solution phase. The SQSs presented in this work can be widely used to study the behavior of ternary fcc solid solutions

Thorium determination by x-ray fluorescence spectrometry in simulated thorex process solutions

International Nuclear Information System (INIS)

Yamaura, M.; Matsuda, H.T.

1991-11-01

The X-ray fluorescence method for thorium determination in aqueous and organic (TBP/n-dodecane) solutions is described. The thin film technique for sample preparation and a suitable internal standard had been used. The best conditions for Thorium determination had been established studying some parameters as analytical line, internal standard, filter paper, paper geometry, sample volume and measurement conditions. With the established conditions, thorium was concentration range of to 200 g Th/L and in organic solutions (2-63g Th/L) with 1,5% of precision. The accuracy of the proposed method was 3% in aqueous and organic phases. The detection limit was 1,2μg thorium for aqueous solutions and 1,4μg for organic solutions. Uranium, fission products, corrosion products and Thorex reagent components were studied as interfering elements in the thorium analysis. The matrix effect was also studied using the Thorex process simulated solutions. Finally, the method was applied to thorium determination in irradiated thorium solutions with satisfactory results. (author)

Inter-Governmental E-Government Processes:Comparison of Different Solution Approaches- Based on Examples from Switzerland / Europe

Directory of Open Access Journals (Sweden)

Frank Zimmermann

2006-12-01

Full Text Available The main objective of this article is to describe different solution approaches for e-Government processes across different institutions at different levels of public administrations: a phased approach for specific e-Government solutions and a platform approach for cross-organisational public services. We discuss selection criteria for the different approaches considering several examples and indicate a relationship between the expected return-on-investment and the complexity of the solution.

Processing Solutions for Big Data in Astronomy

Science.gov (United States)

Fillatre, L.; Lepiller, D.

2016-09-01

This paper gives a simple introduction to processing solutions applied to massive amounts of data. It proposes a general presentation of the Big Data paradigm. The Hadoop framework, which is considered as the pioneering processing solution for Big Data, is described together with YARN, the integrated Hadoop tool for resource allocation. This paper also presents the main tools for the management of both the storage (NoSQL solutions) and computing capacities (MapReduce parallel processing schema) of a cluster of machines. Finally, more recent processing solutions like Spark are discussed. Big Data frameworks are now able to run complex applications while keeping the programming simple and greatly improving the computing speed.

Cementation feasibility of a uranium-thorium based solution by physical and mechanical characterization

International Nuclear Information System (INIS)

Carpentiero, R.; Luce, A.; Troiani, F.

2002-01-01

By reprocessing Elk River nuclear fuel, at the ENEA ITREC Plant (South of Italy), about 3 m 3 of Uranium-Thorium based solution were produced. Previously considered an intermediate product to be further treated to recover U and Th, it is now being considered a waste, due to considerable content of fission products and to phasing out of the Italian nuclear industry. Together with other treatment options, a conditioning process in cement matrix is being evaluated, supported by some chemical, physical and mechanical tests on samples prepared with simulated waste. The main components selected to simulate the real solution were thorium nitrate (at two different concentrations), ferrous nitrate and nitric acid. This solution has been neutralized with sodium carbonate (at two different concentration) and cemented by means of a properly defined formulation. Pozzolanic blend cement, at different water to cement ratio, with and without a silica type additive, has been investigated. Cubic samples were subjected to compression tests and repeated freeze-thaw cycles followed by compression tests. Cylindrical samples were subjected to a leach test (according. to the tn ANSI/ANS-16.1 standard). The obtained results are above the minimum acceptance values established by the Italian authority. The evaluated properties are the first important elements to estimate the long term-instability of conditioned radioactive waste. Meanwhile a preliminary theoretical study has been done to evaluate the gas evolution from the matrix due to radiolysis effect. The reached conclusions encourage the development of further analysis to implement a cementation facility. (Author)

PHASES: Opto-mechanical solutions to perform absolute spectrophotometry from space

Directory of Open Access Journals (Sweden)

Vather Dinesh

2013-04-01

Full Text Available This work provides an update of the current status of PHASES, which is a project aimed at developing a space-borne telescope to perform absolute flux calibrated spectroscopy of bright stars. PHASES will make it possible to measure micromagnitude photometric variations due to, e.g., exo-planet/moon transits. It is designed to obtain 1% RMS flux calibrated low resolution spectra in the wavelength range 370–960 nm with signal-to-noise ratios >100 for stars with V<10 in short integration times of ∼1 minute. The strategy to calibrate the system using A-type stars is outlined. PHASES will make possible a complete characterization of stars, some of them hosting planets. From the comparison of observed spectra with accurate model atmospheres stellar angular diameters will be determined with precisions of ∼0.5%. The light curves of transiting systems will be then used to extract the radius of the planet with similar precision. The demanding scientific requirements to be achieved under extreme observing conditions have shaped the optomechanical design. A computational model and a high-precision interferometric system have been developed to test the performance of the instrument.

Evolution of the corrosion process of AA 2024-T3 in an alkaline NaCl solution with sodium dodecylbenzenesulfonate and lanthanum chloride inhibitors

International Nuclear Information System (INIS)

Zhou, Biner; Wang, Yishan; Zuo, Yu

2015-01-01

Highlights: • Inhibition effect of LaCl 3 and SDBS for AA 2024 in NaCl solution (pH 10) was studied. • At the beginning the active polarization behavior of the alloy changed to passivation. • The passive behavior gradually disappeared with time and pitting happened at S-phases. • The compounded inhibitors showed good inhibition but cannot totally inhibit pitting. • The adsorption of SDBS played the key role for inhibition to the corrosion process. - Abstract: The evolution of the corrosion process of AA 2024-T3 in 0.58 g L −1 NaCl solution (pH 10) with sodium dodecylbenzenesulfonate (SDBS) and lanthanum chloride inhibitors was studied with electrochemical and surface analysis methods. With the addition of the compounded LaCl 3 and SDBS inhibitors, in the early stage the polarization behavior of AA 2024-T3 changed from active corrosion to passivation, and both the general corrosion and pitting corrosion were inhibited. However, with the immersion time extended, the passive behavior gradually disappeared and pitting happened at the Cu-rich phases. After 24 h immersion, the compounded inhibitors still showed good inhibition for general corrosion, but the polarization curve again presented the characteristic similar to active polarization. The compounded inhibitors also inhibited the pitting corrosion to some extent. The acting mechanism of the inhibitors SDBS and La 3 Cl on the corrosion process of AA 2024-T3 in the test solution was discussed.

FaCT phase-I evaluation on the advanced aqueous reprocessing process (2). Development of mechanical disassembly and short stroke shearing systems for FBR fuel reprocessing

International Nuclear Information System (INIS)

Takeuchi, Masayuki; Kitagaki, Toru; Higuchi, Hidetoshi; Fukushima, Mineo; Washiya, Tadahiro; Kobayashi, Tsuguyuki

2011-01-01

JAEA promotes a development of an advanced head-end process in FaCT project. We selected mechanical cutting method for disassembly process and short stroke method for shearing process. In the FaCT phase-I, the criteria was set for decision about the innovative technology and some fundamental performances of the innovative technology such as precision, speed, durability, operation performance and system concept were discussed by the engineering test and design work. We designed and fabricated an engineering-scale test device for mechanical disassembly and short stroke shearing and have carried out the engineering tests using simulated fuel assemblies. As a part of the engineering test results, the effects of cutting conditions on the durability of cutting tool and cutting stability were discussed. Also, the reduction of magazine width is effective to improve the precision of sheared pin length, and the bundle of simulated fuel pins were successfully sheared to 10 ± 5mm, which is a target for the sheared pin length. The criteria for the mechanical disassembly technology and the short stroke shearing technology were satisfied, so we judged that the development of innovative technologies has worth going on for the next phase in the FaCT project. (author)

Study on microstructure and strengthening mechanism of AZ91-Y magnesium alloy

Science.gov (United States)

Cai, Huisheng; Guo, Feng; Su, Juan; Liu, Liang; Chen, Baodong

2018-03-01

AZ91-Y magnesium alloy with different thicknesses were prepared by die casting process. The main existence forms of Y in alloy and the effects of Y on microstructure and mechanical properties of alloy were studied, the main reason for the change of mechanical properties and fracture mechanism were analyzed. The results show that, yttrium exists mainly in the forms of Al2Y phase and trace solid solution in α-Mg. Yttrium can refine the grain of α-Mg, reduce the amount of eutectic β-Mg17Al12 phase and promote its discrete distribution. The room temperature tensile strength and elongation of alloy increased first and then decreased with the increase of Y content. The designed alloys containing 0.6% Y (measured containing 0.63% Y) have better mechanical properties. The change of mechanical properties of alloy is a comprehensive reflection of the effect of solid solution, grain refinement and second phase. The cracking of Al2Y phase and β-Mg17Al12 phase and crack propagation through Al2Y phase and β-Mg17Al12 phase are the main fracture mechanism of magnesium alloy containing yttrium. The cooling rate does not change the trend of the influence of Y, but affects the degree of influence of Y.

Retention of Halogenated Solutes on Stationary Phases Containing Heavy Atoms

Directory of Open Access Journals (Sweden)

Toshio Miwa

2013-05-01

Full Text Available To examine the effects of weak intermolecular interactions on solid-phase extraction (SPE and chromatographic separation, we synthesized some novel stationary phases with a heavy atom effect layer by immobilizing halogenated aromatic rings and hydroxyl groups onto the surface of a hydrophilic base polymer. Using SPE cartridges packed with the functionalized materials, we found that the heavy atom stationary phases could selectively retain halophenols in organic solvents, such as 1-propanol which blocks the hydrogen bonding, or acetonitrile which blocks the p-p interaction. The extraction efficiency of the materials toward the halophenols depended on the dipole moments of phenoxy groups present as functional groups. On the other hand, the extraction efficiency of solutes toward the functional group depended on their molar refractions, i.e., induced dipole moments. The retention of the solutes to the stationary phase ultimately depended on not only strong intermolecular interactions, but also the effects of weak interactions such as the dispersion force.

Automatically varying the composition of a mixed refrigerant solution for single mixed refrigerant LNG (liquefied natural gas) process at changing working conditions

International Nuclear Information System (INIS)

Xu, Xiongwen; Liu, Jinping; Cao, Le; Pang, Weiqiang

2014-01-01

The SMR (single mixed refrigerant) process is widely used in the small- and medium-scale liquefaction of NG (natural gas). Operating the MR (mixed-refrigerant) process outside of the design specifications is difficult but essential to save energy. Nevertheless, it is difficult to realize because the process needs to alter the working refrigerant composition. To address this challenge, this study investigated the performance diagnosis mechanism for SMR process. A control strategy was then proposed to control the changes in working refrigerant composition under different working conditions. This strategy separates the working refrigerant flow in the SMR process into three flows through two phase separators before it flows into the cold box. The first liquid flow is rich in the high-temperature component (isopentane). The second liquid flow is rich in the middle-temperature components (ethylene and propane), and the gas flow is rich in the low-temperature components (nitrogen and methane). By adjusting the flow rates, it is easy to decouple the control variables and automate the system. Finally, this approach was validated by process simulation and shown to be highly adaptive and exergy efficient in response to changing working conditions. - Highlights: • The performance diagnosis mechanism of SMR LNG process is studied. • A measure to automatically change the operation composition as per the working conditions is proposed for SMR process. • SMR process simulation is performed to verify the validity of the control solution. • The control solution notably improves the energy efficiency of SMR process at changing working condition

Structures and solid solution mechanisms of pyrochlore phases in the systems Bi2O3-ZnO-(Nb, Ta)2O5

International Nuclear Information System (INIS)

Tan, K.B.; Khaw, C.C.; Lee, C.K.; Zainal, Z.; Miles, G.C.

2010-01-01

Research highlights: → Combined XRD and ND Rietveld structural refinement of pyrochlores. → Structures and solid solution mechanisms of Bi-pyrochlores. → Bi and Zn displaced off-centre to different 96g A-site positions. → Summary of composition-structure-property of Bi-pyrochlores. - Abstract: The crystal structures of two pyrochlore phases have been determined by Rietveld refinement of combined X-ray and neutron powder diffraction data. These are stoichiometric, Bi 1.5 ZnTa 1.5 O 7 and non-stoichiometric Bi 1.56 Zn 0.92 Nb 1.44 O 6.86 . In both structures, Zn is distributed over A- and B-sites; Bi and Zn are displaced off-centre, to different 96g A-site positions; of the three sets of oxygen positions, O(1) are full, O(2) contain vacancies and O(3) contain a small number of oxygen, again in both cases. Comparisons between these structures, those of related Sb analogues and literature reports are made.

Facile solution-processed aqueous MoOx for feasible application in organic light-emitting diode

Science.gov (United States)

Zheng, Qinghong; Qu, Disui; Zhang, Yan; Li, Wanshu; Xiong, Jian; Cai, Ping; Xue, Xiaogang; Liu, Liming; Wang, Honghang; Zhang, Xiaowen

2018-05-01

Solution-processed techniques attract increasing attentions in organic electronics for their low-cost and scalable manufacturing. We demonstrate the favorite hole injection material of solution-processed aqueous MoOx (s-MoOx) with facile fabrication process and cast successful application to constructing efficient organic light-emitting diodes (OLEDs). Atomic force microscopy and X-ray photoelectron spectroscopy analysis show that s-MoOx behaves superior film morphology and non-stoichiometry with slight oxygen deficiency. With tris(8-hydroxy-quinolinato)aluminium as emitting layer, s-MoOx based OLED shows maximum luminous efficiency of 7.9 cd/A and power efficiency of 5.9 lm/W, which have been enhanced by 43.6% and 73.5%, respectively, in comparison with the counterpart using conventional vacuum thermal evaporation MoOx. Current-voltage, impedance-voltage, phase-voltage and capacitance-voltage characteristics of hole-only devices indicate that s-MoOx with two processes of "spin-coating/annealing" shows mostly enhanced hole injection capacity and thus promoting device performance. Our experiments provide an alternative approach for constructing efficient OLED with solution process.

Phase Behaviour and Miscibility Studies of Collagen/Silk Fibroin Macromolecular System in Dilute Solutions and Solid State.

Science.gov (United States)

Ghaeli, Ima; de Moraes, Mariana A; Beppu, Marisa M; Lewandowska, Katarzyna; Sionkowska, Alina; Ferreira-da-Silva, Frederico; Ferraz, Maria P; Monteiro, Fernando J

2017-08-18

Miscibility is an important issue in biopolymer blends for analysis of the behavior of polymer pairs through the detection of phase separation and improvement of the mechanical and physical properties of the blend. This study presents the formulation of a stable and one-phase mixture of collagen and regenerated silk fibroin (RSF), with the highest miscibility ratio between these two macromolecules, through inducing electrostatic interactions, using salt ions. For this aim, a ternary phase diagram was experimentally built for the mixtures, based on observations of phase behavior of blend solutions with various ratios. The miscibility behavior of the blend solutions in the miscible zones of the phase diagram was confirmed quantitatively by viscosimetric measurements. Assessing the effects of biopolymer mixing ratio and salt ions, before and after dialysis of blend solutions, revealed the importance of ion-specific interactions in the formation of coacervate-based materials containing collagen and RSF blends that can be used in pharmaceutical, drug delivery, and biomedical applications. Moreover, the conformational change of silk fibroin from random coil to beta sheet, in solution and in the final solid films, was detected by circular dichroism (CD) and Fourier transform infrared spectroscopy (FTIR), respectively. Scanning electron microscopy (SEM) exhibited alterations of surface morphology for the biocomposite films with different ratios. Surface contact angle measurement illustrated different hydrophobic properties for the blended film surfaces. Differential scanning calorimetry (DSC) showed that the formation of the beta sheet structure of silk fibroin enhances the thermal stability of the final blend films. Therefore, the novel method presented in this study resulted in the formation of biocomposite films whose physico-chemical properties can be tuned by silk fibroin conformational changes by applying different component mixing ratios.

Thermodynamically Consistent Algorithms for the Solution of Phase-Field Models

KAUST Repository

Vignal, Philippe

2016-02-11

Phase-field models are emerging as a promising strategy to simulate interfacial phenomena. Rather than tracking interfaces explicitly as done in sharp interface descriptions, these models use a diffuse order parameter to monitor interfaces implicitly. This implicit description, as well as solid physical and mathematical footings, allow phase-field models to overcome problems found by predecessors. Nonetheless, the method has significant drawbacks. The phase-field framework relies on the solution of high-order, nonlinear partial differential equations. Solving these equations entails a considerable computational cost, so finding efficient strategies to handle them is important. Also, standard discretization strategies can many times lead to incorrect solutions. This happens because, for numerical solutions to phase-field equations to be valid, physical conditions such as mass conservation and free energy monotonicity need to be guaranteed. In this work, we focus on the development of thermodynamically consistent algorithms for time integration of phase-field models. The first part of this thesis focuses on an energy-stable numerical strategy developed for the phase-field crystal equation. This model was put forward to model microstructure evolution. The algorithm developed conserves, guarantees energy stability and is second order accurate in time. The second part of the thesis presents two numerical schemes that generalize literature regarding energy-stable methods for conserved and non-conserved phase-field models. The time discretization strategies can conserve mass if needed, are energy-stable, and second order accurate in time. We also develop an adaptive time-stepping strategy, which can be applied to any second-order accurate scheme. This time-adaptive strategy relies on a backward approximation to give an accurate error estimator. The spatial discretization, in both parts, relies on a mixed finite element formulation and isogeometric analysis. The codes are

Quantum mechanics in phase space

DEFF Research Database (Denmark)

Hansen, Frank

1984-01-01

A reformulation of quantum mechanics for a finite system is given using twisted multiplication of functions on phase space and Tomita's theory of generalized Hilbert algebras. Quantization of a classical observable h is achieved when the twisted exponential Exp0(-h) is defined as a tempered....... Generalized Weyl-Wigner maps related to the notion of Hamiltonian weight are studied and used in the formulation of a twisted spectral theory for functions on phase space. Some inequalities for Wigner functions on phase space are proven. A brief discussion of the classical limit obtained through dilations...

The mechanism of solute-enriched clusters formation in neutron-irradiated pressure vessel steels: The case of Fe-Cu model alloys

Energy Technology Data Exchange (ETDEWEB)

Subbotin, A.V., E-mail: Alexey.V.Subbotin@gmail.com [Scientific and Production Complex Atomtechnoprom, Moscow 119180 (Russian Federation); Panyukov, S.V., E-mail: panyukov@lpi.ru [PN Lebedev Physics Institute, Russian Academy of Sciences, Moscow 117924 (Russian Federation)

2016-08-15

Mechanism of solute-enriched clusters formation in neutron-irradiated pressure vessel steels is proposed and developed in case of Fe-Cu model alloys. The suggested solute-drag mechanism is analogous to the well-known zone-refining process. We show that the obtained results are in good agreement with available experimental data on the parameters of clusters enriched with the alloying elements. Our model explains why the formation of solute-enriched clusters does not happen in austenitic stainless steels with fcc lattice structure. It also allows to quantify the method of evaluation of neutron irradiation dose for the process of RPV steels hardening.

Two cloud-point phenomena in tetrabutylammonium perfluorooctanoate aqueous solutions: anomalous temperature-induced phase and structure transitions.

Science.gov (United States)

Yan, Peng; Huang, Jin; Lu, Run-Chao; Jin, Chen; Xiao, Jin-Xin; Chen, Yong-Ming

2005-03-24

This paper reported the phase behavior and aggregate structure of tetrabutylammonium perfluorooctanoate (TBPFO), determined by differential scanning calorimeter, electrical conductivity, static/dynamic light scattering, and rheology methods. We found that above a certain concentration the TBPFO solution showed anomalous temperature-dependent phase behavior and structure transitions. Such an ionic surfactant solution exhibits two cloud points. When the temperature was increased, the solution turned from a homogeneous-phase to a liquid-liquid two-phase system, then to another homogeneous-phase, and finally to another liquid-liquid two-phase system. In the first homogeneous-phase region, the aggregates of TBPFO were rodlike micelles and the solution was Newtonian fluid. While in the second homogeneous-phase region, the aggregates of TBPFO were large wormlike micelles, and the solution behaved as pseudoplastic fluid that also exhibited viscoelastic behavior. We thought that the first cloud point might be caused by the "bridge" effect of the tetrabutylammonium counterion between the micelles and the second one by the formation of the micellar network.

Insight into black hole phase transition from parametric solutions

Science.gov (United States)

Li, Dandan; Li, Shanshan; Mi, Li-Qin; Li, Zhong-Heng

2017-12-01

We consider the first-order phase transition of a charged anti-de Sitter black hole and introduce a new dimensionless parameter, ω =(Δ S /π Q2)2 . The parametric solutions of the two reduced volumes are obtained. Each volume is described by a piecewise analytic function. The demarcation point is located at ωd=12 (2 √{3 }-3 ). The volume function is smoothly connected at the point. We show that all properties of the coexistence curve can be studied from the two volume functions. In other words, an arbitrary reduced thermodynamic variable of the two coexisting phases is only a function of ω . Some phase diagrams are plotted by using parametric solutions. We find that, when the reduced pressure P ^>P^A (of order 7.4 ×10-4), the first-order phase transition of the black hole is similar to the van der Waals fluid. However, the similarity disappears when P ^≤P^A. At a van der Waals fluidlike stage, the values of the reduced Gibbs function and the reduced density average are equal. At a non-van der Waals fluid stage, the phase diagrams have extraordinarily rich structure. It is worth pointing out that the phase transition is very important for the low-pressure case since the pressure in essence is the cosmological constant, which is normally very small. Moreover, the thermodynamic behaviors as ω →0 are discussed, from which one can easily obtain some critical exponents and amplitudes for small-large black hole phase transitions.

Phase transformations in nickel sulphide: Microstructures and mechanisms

International Nuclear Information System (INIS)

Yousfi, Oussama; Donnadieu, Patricia; Brechet, Yves; Robaut, Florence; Charlot, Frederic; Kasper, Andreas; Serruys, Francis

2010-01-01

Nickel sulphide inclusions are known to be responsible for delayed fracture in tempered glasses due to phase transformation within the inclusion. Microstructural identification of the phase transformation mechanisms in the Ni-S system close to the NiS composition were carried out on a series of partially transformed states. Observations allow to investigate the morphological evolution during transformation, the phase orientation relationships and the first stages of the transformation were investigated by optical microscopy, electron backscatter diffraction, and scanning and transmission electron microscopy. The transformation mechanisms change significantly with the change in sulphur content of the α-NiS phase. Massive transformation is observed for near-stoichiometric composition. For overstoichiometric composition, the transformation is controlled by a long-range diffusion mechanism. The influence of stoichiometry and impurities (Fe) on the microstructural evolution and transformation mechanisms has also been studied.

Mechanical properties examined by nanoindentation for selected phases relevant to the development of monolithic uranium-molybdenum metallic fuels

Energy Technology Data Exchange (ETDEWEB)

Newell, Ryan; Park, Youngjoo; Mehta, Abhishek [Department of Materials Science and Engineering, University of Central Florida, Orlando, FL, 32826 (United States); Keiser, Dennis [Nuclear Fuels and Materials Division, Idaho National Laboratory, Idaho Falls, ID, 83402 (United States); Sohn, Yongho, E-mail: Yongho.Sohn@ucf.edu [Department of Materials Science and Engineering, University of Central Florida, Orlando, FL, 32826 (United States)

2017-04-15

Nanomechanical properties, specifically the reduced modulus and hardness of several intermetallic and solid solution phases are reported to assist the development of the U-10 wt% Mo (U-10Mo) monolithic fuel system for research and test reactors. Findings from this study and reported values of mechanical properties provide data critical for understanding and predicting the structural behavior of the fuel system during fabrication and irradiation. The phases examined are products of interdiffusion and reaction between (1) the AA6061 cladding and the Zr diffusion barrier, namely (Al,Si){sub 3}Zr and Al{sub 3}Zr, (2) the U-10Mo fuel and the Zr diffusion barrier, namely UZr{sub 2}, Mo{sub 2}Zr, and α-U, and (3) the U (or U-10Mo) and Mo, namely a mixture gradient of α- and γ-phases. The UC inclusions observed within the fuel alloy were also examined. Only phases present in thick or continuous microstructure on cross-sectioned fuel plates and diffusion couples were investigated for reduced modulus and hardness. Concentration-dependence of room-temperature reduced modulus in U solid solution with 0–10 wt% Mo was semi-quantitatively modeled based on mixture of α- and γ-phases and solid solutioning within the γ-phase.

Mechanical properties examined by nanoindentation for selected phases relevant to the development of monolithic uranium-molybdenum metallic fuels

Science.gov (United States)

Newell, Ryan; Park, Youngjoo; Mehta, Abhishek; Keiser, Dennis; Sohn, Yongho

2017-04-01

Nanomechanical properties, specifically the reduced modulus and hardness of several intermetallic and solid solution phases are reported to assist the development of the U-10 wt% Mo (U-10Mo) monolithic fuel system for research and test reactors. Findings from this study and reported values of mechanical properties provide data critical for understanding and predicting the structural behavior of the fuel system during fabrication and irradiation. The phases examined are products of interdiffusion and reaction between (1) the AA6061 cladding and the Zr diffusion barrier, namely (Al,Si)3Zr and Al3Zr, (2) the U-10Mo fuel and the Zr diffusion barrier, namely UZr2, Mo2Zr, and α-U, and (3) the U (or U-10Mo) and Mo, namely a mixture gradient of α- and γ-phases. The UC inclusions observed within the fuel alloy were also examined. Only phases present in thick or continuous microstructure on cross-sectioned fuel plates and diffusion couples were investigated for reduced modulus and hardness. Concentration-dependence of room-temperature reduced modulus in U solid solution with 0-10 wt% Mo was semi-quantitatively modeled based on mixture of α- and γ-phases and solid solutioning within the γ-phase.

Investigation on the formation of Cu-Fe nano crystalline super-saturated solid solution developed by mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

Mojtahedi, M., E-mail: m.mojtahedi@gmail.com [School of Materials Science and Engineering, Iran University of Science and Technology, Narmak, Tehran 16846-13114 (Iran, Islamic Republic of); Goodarzi, M.; Aboutalebi, M.R. [School of Materials Science and Engineering, Iran University of Science and Technology, Narmak, Tehran 16846-13114 (Iran, Islamic Republic of); Ghaffari, M. [Department of Electrical and Electronics Engineering, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800 (Turkey); Soleimanian, V. [Department of Physics, Faculty of Science, Shahrekord University, P.O. Box 115, Shahrekord (Iran, Islamic Republic of)

2013-02-15

Highlights: Black-Right-Pointing-Pointer The deformation of the mechanically alloyed Cu-Fe powder is anisotropic. Black-Right-Pointing-Pointer The Rietveld method is more proper and results in smaller crystallite size than the Scherer and Williamson-Hall methods. Black-Right-Pointing-Pointer A dual phase super saturated solid solution achieved after 96 h of milling of the mixtures with 30, 50 and 70 wt.% of Iron. Black-Right-Pointing-Pointer A final proportion of approximately 85% FCC and 15% BCC structure obtained in all of the applied compositions. - Abstract: In this study, the formation of super saturated solid solution in the binary Cu-Fe system was investigated. Three powder blends with 30, 50 and 70 wt.% of Fe were milled for different times to 96 h. The variations of lattice parameter and inter-planar spacing were calculated and analyzed using X-ray diffraction analysis (XDA). The anisotropy of lattice deformation in the FCC phase was studied and the obtained results were compared to milled pure Cu powder. Furthermore, crystallite size was calculated using Scherer formula in comparison with Rietveld full profile refinement method. Considering the previous studies about the formation of non-equilibrium FCC and BCC phases, the phase evolution has been discussed and the proportion of each phase was calculated using Rietveld refinement method. Supplementary studies on the evolution of microstructure and formation of solid solution were carried out using high resolution transmission electron microscopy (HRTEM). Finally, high angle annular dark field (HAADF) imaging was utilized to find out the level of homogeneity in the resulting phases. While true alloying takes place in each phase, the final structure consists of both FCC and BCC nano-crystallites.

Liquid-Phase Packaging of a Glucose Oxidase Solution with Parylene Direct Encapsulation and an Ultraviolet Curing Adhesive Cover for Glucose Sensors

Directory of Open Access Journals (Sweden)

Seiichi Takamatsu

2010-06-01

Full Text Available We have developed a package for disposable glucose sensor chips using Parylene encapsulation of a glucose oxidase solution in the liquid phase and a cover structure made of an ultraviolet (UV curable adhesive. Parylene was directly deposited onto a small volume (1 μL of glucose oxidase solution through chemical vapor deposition. The cover and reaction chamber were constructed on Parylene film using a UV-curable adhesive and photolithography. The package was processed at room temperature to avoid denaturation of the glucose oxidase. The glucose oxidase solution was encapsulated and unsealed. Glucose sensing was demonstrated using standard amperometric detection at glucose concentrations between 0.1 and 100 mM, which covers the glucose concentration range of diabetic patients. Our proposed Parylene encapsulation and UV-adhesive cover form a liquid phase glucose-oxidase package that has the advantages of room temperature processing and direct liquid encapsulation of a small volume solution without use of conventional solidifying chemicals.

(Nbx, Zr1-x)4AlC3 MAX Phase Solid Solutions: Processing, Mechanical Properties, and Density Functional Theory Calculations.

Science.gov (United States)

Lapauw, Thomas; Tytko, Darius; Vanmeensel, Kim; Huang, Shuigen; Choi, Pyuck-Pa; Raabe, Dierk; Caspi, El'ad N; Ozeri, Offir; To Baben, Moritz; Schneider, Jochen M; Lambrinou, Konstantina; Vleugels, Jozef

2016-06-06

The solubility of zirconium (Zr) in the Nb4AlC3 host lattice was investigated by combining the experimental synthesis of (Nbx, Zr1-x)4AlC3 solid solutions with density functional theory calculations. High-purity solid solutions were prepared by reactive hot pressing of NbH0.89, ZrH2, Al, and C starting powder mixtures. The crystal structure of the produced solid solutions was determined using X-ray and neutron diffraction. The limited Zr solubility (maximum of 18.5% of the Nb content in the host lattice) in Nb4AlC3 observed experimentally is consistent with the calculated minimum in the energy of mixing. The lattice parameters and microstructure were evaluated over the entire solubility range, while the chemical composition of (Nb0.85, Zr0.15)4AlC3 was mapped using atom probe tomography. The hardness, Young's modulus, and fracture toughness at room temperature as well as the high-temperature flexural strength and E-modulus of (Nb0.85, Zr0.15)4AlC3 were investigated and compared to those of pure Nb4AlC3. Quite remarkably, an appreciable increase in fracture toughness was observed from 6.6 ± 0.1 MPa/m(1/2) for pure Nb4AlC3 to 10.1 ± 0.3 MPa/m(1/2) for the (Nb0.85, Zr0.15)4AlC3 solid solution.

Approximate Analytic Solutions for the Two-Phase Stefan Problem Using the Adomian Decomposition Method

Directory of Open Access Journals (Sweden)

Xiao-Ying Qin

2014-01-01

Full Text Available An Adomian decomposition method (ADM is applied to solve a two-phase Stefan problem that describes the pure metal solidification process. In contrast to traditional analytical methods, ADM avoids complex mathematical derivations and does not require coordinate transformation for elimination of the unknown moving boundary. Based on polynomial approximations for some known and unknown boundary functions, approximate analytic solutions for the model with undetermined coefficients are obtained using ADM. Substitution of these expressions into other equations and boundary conditions of the model generates some function identities with the undetermined coefficients. By determining these coefficients, approximate analytic solutions for the model are obtained. A concrete example of the solution shows that this method can easily be implemented in MATLAB and has a fast convergence rate. This is an efficient method for finding approximate analytic solutions for the Stefan and the inverse Stefan problems.

Analytical solution of laminar-laminar stratified two-phase flows with curved interfaces

International Nuclear Information System (INIS)

Brauner, N.; Rovinsky, J.; Maron, D.M.

1995-01-01

The present study represents a complete analytical solution for laminar two-phase flows with curved interfaces. The solution of the Navier-Stokes equations for the two-phases in bipolar coordinates provides the 'flow monograms' describe the relation between the interface curvature and the insitu flow geometry when given the phases flow rates and viscosity ratios. Energy considerations are employed to construct the 'interface monograms', whereby the characteristic interfacial curvature is determined in terms of the phases insitu holdup, pipe diameter, surface tension, fluids/wall adhesion and gravitation. The two monograms are then combined to construct the system 'operational monogram'. The 'operational monogram' enables the determination of the interface configuration, the local flow characteristics, such as velocity profiles, wall and interfacial shear stresses distribution as well as the integral characteristics of the two-phase flow: phases insitu holdup and pressure drop

Analytical solution of laminar-laminar stratified two-phase flows with curved interfaces

Energy Technology Data Exchange (ETDEWEB)

Brauner, N.; Rovinsky, J.; Maron, D.M. [Tel-Aviv Univ. (Israel)

1995-09-01

The present study represents a complete analytical solution for laminar two-phase flows with curved interfaces. The solution of the Navier-Stokes equations for the two-phases in bipolar coordinates provides the `flow monograms` describe the relation between the interface curvature and the insitu flow geometry when given the phases flow rates and viscosity ratios. Energy considerations are employed to construct the `interface monograms`, whereby the characteristic interfacial curvature is determined in terms of the phases insitu holdup, pipe diameter, surface tension, fluids/wall adhesion and gravitation. The two monograms are then combined to construct the system `operational monogram`. The `operational monogram` enables the determination of the interface configuration, the local flow characteristics, such as velocity profiles, wall and interfacial shear stresses distribution as well as the integral characteristics of the two-phase flow: phases insitu holdup and pressure drop.

Phase transitions in solid Kr-CH4 solutions and rotational excitations in phase II

International Nuclear Information System (INIS)

Bagatskii, M.I.; Mashchenko, D.A.; Dudkin, V.V.

2007-01-01

The heat capacity C p of solid Kr-n CH 4 solutions with the CH 4 concentrations n=0.82, 0.86, 0.90 as well as solutions with n=0.90, 0.95 doped with 0.002 O 2 impurity has been investigated under equilibrium vapor pressure over the internal 1-24 K. The (T,n)-phase diagram was refined and the region of two-phase states was determined for Kr-n CH 4 solid solutions. The contribution of the rotational subsystem, C r ot, to the heat capacity of the solutions has been separated. Analysis of C r ot(T) at T 1 and E 2 between the tunnel levels of the A-, T- and A-, E--nuclear-spin species of CH 4 molecules in the orientationally ordered subsystem, and to determine the effective energy gaps E 1 between lowest levels of the A- and T- species. The relations τ(n) and E 1 (n) stem from changes of the effective potential field caused as the replacement of CH 4 molecules by Kr atoms at sites of the ordered sublattices. The effective gaps E L between a group of tunnel levels of the ground-state liberation state and the nearest group of excited levels of the liberation state of the ordered CH 4 molecules in the solutions with n=0.90 (E L =52 K) and 0.95 (E L =55 K) has been estimated

A solution-processed binary cathode interfacial layer facilitates electron extraction for inverted polymer solar cells.

Science.gov (United States)

Zhang, Xinyuan; Li, Zhiqi; Liu, Chunyu; Guo, Jiaxin; Shen, Liang; Guo, Wenbin

2018-03-15

The charge transfer and separation are significantly affected by the electron properties of the interface between the electron-donor layer and the carrier-transporting layer in polymer solar cells (PSCs). In this study, we investigate the electron extraction mechanism of PSCs with a low temperature solution-processed ZnO/PEI as electron transport layer. The incorporation of PEI layer can decrease the work function of ZnO and reduce interfacial barrier, which facilitates electron extraction and suppresses bimolecular recombination, leading to a significant performance enhancement. Furthermore, PEI layer can induce phase separation and passivite inorganic surface trap states as well as shift the interfacial energy offset between metal oxide and organic materials. This work offers a simple and effective way to improve the charge transporting property of organic photovoltaic devices. Copyright © 2017 Elsevier Inc. All rights reserved.

Fabrication of nanocrystalline alloys Cu–Cr–Mo super satured solid solution by mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

Aguilar, C., E-mail: claudio.aguilar@usm.cl [Departamento de Ingeniería Metalúrgica y Materiales, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Guzmán, D. [Departamento de Ingeniería en Metalurgia, Facultad de Ingeniería, Universidad de Atacama y Centro Regional de Investigación y Desarrollo Sustentable de Atacama (CRIDESAT), Av. Copayapu 485, Copiapó (Chile); Castro, F.; Martínez, V.; Cuevas, F. de las [Centro de Estudios e Investigaciones Técnicas de Gipuzkoa, Paseo de Manuel Lardizábal, N° 15, 20018 San Sebastián (Spain); Lascano, S. [Departamento de Ingeniería Mecánica, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Muthiah, T. [Departamento de Ingeniería Metalúrgica y Materiales, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile)

2014-08-01

This work discusses the extension of solid solubility of Cr and Mo in Cu processed by mechanical alloying. Three alloys processed, Cu–5Cr–5Mo, Cu–10Cr–10Mo and Cu–15Cr–15Mo (weight%) using a SPEX mill. Gibbs free energy of mixing values 10, 15 and 20 kJ mol{sup −1} were calculated for these three alloys respectively by using the Miedema's model. The crystallite size decreases and dislocation density increases when the milling time increases, so Gibbs free energy storage in powders increases by the presence of crystalline defects. The energy produced by crystallite boundaries and strain dislocations were estimated and compared with Gibbs free energy of mixing values. The energy storage values by the presence of crystalline defects were higher than Gibbs free energy of mixing at 120 h for Cu–5Cr–5Mo, 130 h for Cu–10Cr–10Mo and 150 h for Cu–15Cr–15Mo. During milling, crystalline defects are produced that increases the Gibbs free energy storage and thus the Gibbs free energy curves are moved upwards and hence the solubility limit changes. Therefore, the three alloys form solid solutions after these milling time, which are supported with the XRD results. - Highlights: • Extension of solid solution Cr and Mo in Cu achieved by mechanical alloying. • X-ray characterization of Cu–Cr–Mo system processed by mechanical alloying. • Thermodynamics analysis of formation of solid solution of the Cu–Cr–Mo system.

Numerical Solutions of Mechanical Turbulent Filtration Equation Used in Mechatronics and Micro Mechanic

OpenAIRE

Hassan Fathabadi

2013-01-01

In this study, several novel numerical solutions are presented to solve the turbulent filtration equation and its special case called “Non-Newtonian mechanical filtration equation”. The turbulent filtration equation in porous media is a very important equation which has many applications to solve the problems appearing especially in mechatronics, micro mechanic and fluid mechanic. Many applied mechanical problems can be solved using this equation. For example, non-Newtonian mechanical filtrat...

Phase fields of nickel silicides obtained by mechanical alloying in the nanocrystalline state

Science.gov (United States)

Datta, M. K.; Pabi, S. K.; Murty, B. S.

2000-06-01

Solid state reactions induced by mechanical alloying (MA) of elemental blends of Ni and Si have been studied over the entire composition range of the Ni-Si system. A monotonous increase of the lattice parameter of the Ni rich solid solution, Ni(Si), is observed with refinement of crystallite size. Nanocrystalline phase/phase mixtures of Ni(Si), Ni(Si)+Ni31Si12, Ni31Si12+Ni2Si, Ni2Si+NiSi and NiSi+Si, have been obtained during MA, over the composition ranges of 0-10, 10-28, 28-33, 33-50, and >50 at. % Si, respectively. The results clearly suggest that only congruent melting phases, Ni31Si12, Ni2Si, and NiSi form, while the formation of noncongruent melting phases, Ni3Si, Ni3Si2, and NiSi2, is bypassed in the nanocrystalline state. The phase formation during MA has been discussed based on thermodynamic arguments. The predicted phase fields obtained from effective free energy calculations are quite consistent with those obtained during MA.

Phase diagram of the ABC model with nonconserving processes

International Nuclear Information System (INIS)

Lederhendler, A; Cohen, O; Mukamel, D

2010-01-01

The three species ABC model of driven particles on a ring is generalized to include vacancies and particle-nonconserving processes. The model exhibits phase separation at high densities. For equal average densities of the three species, it is shown that although the dynamics is local, it obeys detailed balance with respect to a Hamiltonian with long-range interactions, yielding a nonadditive free energy. The phase diagrams of the conserving and nonconserving models, corresponding to the canonical and grand-canonical ensembles, respectively, are calculated in the thermodynamic limit. Both models exhibit a transition from a homogeneous to a phase-separated state, although the phase diagrams are shown to differ from each other. This conforms with the expected inequivalence of ensembles in equilibrium systems with long-range interactions. These results are based on a stability analysis of the homogeneous phase and exact solution of the continuum equations of the models. They are supported by Monte Carlo simulations. This study may serve as a useful starting point for analyzing the phase diagram for unequal densities, where detailed balance is not satisfied and thus a Hamiltonian cannot be defined

Continued development of a semianalytical solution for two-phase fluid and heat flow in a porous medium

Energy Technology Data Exchange (ETDEWEB)

Doughty, C.; Pruess, K. [Lawrence Berkeley Lab., CA (United States)

1991-06-01

Over the past few years the authors have developed a semianalytical solution for transient two-phase water, air, and heat flow in a porous medium surrounding a constant-strength linear heat source, using a similarity variable {eta} = r/{radical}t. Although the similarity transformation approach requires a simplified geometry, all the complex physical mechanisms involved in coupled two-phase fluid and heat flow can be taken into account in a rigorous way, so that the solution may be applied to a variety of problems of current interest. The work was motivated by adverse to predict the thermohydrological response to the proposed geologic repository for heat-generating high-level nuclear wastes at Yucca Mountain, Nevada, in a partially saturated, highly fractured volcanic formation. The paper describes thermal and hydrologic conditions near the heat source; new features of the model; vapor pressure lowering; and the effective-continuum representation of a fractured/porous medium.

Influence of the extracted solute on the aggregation of malonamide extractant in organic phases: Consequences for phase stability

International Nuclear Information System (INIS)

Berthon, L.; Martinet, L.; Testard, F.; Madic, Ch.; Zem, Th.

2010-01-01

Due to their amphiphilic properties, malonamide molecules in alkane are organized in reverse micelle type aggregates, composed of a polar core formed by the malonamide polar heads and the extracted solutes, and surrounded by a hydrophobic shell made up of the extractant alkyl chains. The aggregates interact with one another through an attractive potential, leading to the formation of a third phase. This occurs with the splitting of the organic phase into a light phase composed mostly of diluent, and a heavy third phase containing highly concentrated extractant and solutes. In this article, we show that the aggregation (monomer concentration, domain of stability, and attractive potential between micelles) greatly depends on the nature of the extracted solute, whereas the size of aggregate (aggregation number) is only slightly influenced by this. We describe the extraction of water, nitric acid, neodymium nitrate and uranyl nitrate. Strongly polarizable species induce consistently large attraction potentials and a small stability domain for the dispersion of nano-droplets in the solvent. Highly polarizable ions such as lanthanides or uranyl induce more long-range attractive interactions than do protons. (authors)

Aqueous electrochemical mechanisms in actinide residue processing. 1998 annual progress report

International Nuclear Information System (INIS)

Blanchard, D.L. Jr.; Burns, C.J.; Morris, D.E.; Smith, W.H.

1998-01-01

'New and/or improved solutions to the stabilization and volume reduction of nuclear materials processing residues are urgently needed. Mediated electrochemical oxidation/reduction (MEO/R) processes are one such approach for incinerator ash, combustibles, and other solid residues. However, questions remain concerning the mechanisms of these processes, and how they might be optimized. In addition, further research is merited to extend their range of applicability. Recent advances in the study of heterogeneous electron transfer in solid substrates have opened the door for the re-examination of electron transfer processes associated with redox mediated actinide dissolution. The authors develop a deeper understanding of the thermodynamic and mechanistic aspects of heterogeneous electron transfer that lie at the heart of these MEO/R processes. They will also develop and test new approaches based on the results of these fundamental studies using actual residue materials. Key aspects of this proposal include: (1) determination of the potential windows for oxidation/reduction of colloidal actinide oxides and actinide-bearing oxide and organic substrates and the e transfer kinetic parameters that govern the current--overpotential characteristics; (2) development of adaptations of mediation schemes and application of co-mediation reagents for oxidative and reductive dissolution based on complexation of the surface-bound or solid-phase actinides and/or the dissolved redox mediator;and (3) execution of bench-scale tests of new MEO/R schemes on actual residue materials.'

Ultrasound Microbubble Treatment Enhances Clathrin-Mediated Endocytosis and Fluid-Phase Uptake through Distinct Mechanisms.

Directory of Open Access Journals (Sweden)

Farnaz Fekri

Full Text Available Drug delivery to tumors is limited by several factors, including drug permeability of the target cell plasma membrane. Ultrasound in combination with microbubbles (USMB is a promising strategy to overcome these limitations. USMB treatment elicits enhanced cellular uptake of materials such as drugs, in part as a result of sheer stress and formation of transient membrane pores. Pores formed upon USMB treatment are rapidly resealed, suggesting that other processes such as enhanced endocytosis may contribute to the enhanced material uptake by cells upon USMB treatment. How USMB regulates endocytic processes remains incompletely understood. Cells constitutively utilize several distinct mechanisms of endocytosis, including clathrin-mediated endocytosis (CME for the internalization of receptor-bound macromolecules such as Transferrin Receptor (TfR, and distinct mechanism(s that mediate the majority of fluid-phase endocytosis. Tracking the abundance of TfR on the cell surface and the internalization of its ligand transferrin revealed that USMB acutely enhances the rate of CME. Total internal reflection fluorescence microscopy experiments revealed that USMB treatment altered the assembly of clathrin-coated pits, the basic structural units of CME. In addition, the rate of fluid-phase endocytosis was enhanced, but with delayed onset upon USMB treatment relative to the enhancement of CME, suggesting that the two processes are distinctly regulated by USMB. Indeed, vacuolin-1 or desipramine treatment prevented the enhancement of CME but not of fluid phase endocytosis upon USMB, suggesting that lysosome exocytosis and acid sphingomyelinase, respectively, are required for the regulation of CME but not fluid phase endocytosis upon USMB treatment. These results indicate that USMB enhances both CME and fluid phase endocytosis through distinct signaling mechanisms, and suggest that strategies for potentiating the enhancement of endocytosis upon USMB treatment may

Effect of Solution Treatment Process on Hardness of Alumina Reinforced Al-9Zn Composite Produced by Squeeze Casting

Directory of Open Access Journals (Sweden)

Dwi Rahmalina

2014-10-01

Full Text Available Characteristics of aluminium matrix composites reinforced by alumina have been developed to improve mechanical properties. One of the determining factors in the development of this material is parameter of solution treatment process. This study discusses the performance of the composite matrix of Al-9Zn-6Mg-3Si reinforced by alumina powder of 5 % volume fraction. Composite are manufactured by squeeze casting process with the pressure of 20 Ton in the metal mould. To improve mechanical properties, the precipitation hardening process is conducted through variation of temperature of solution treatment of 450, 475 and 500 °C and holding time of solution treatment of 30, 60 and 90 minutes. Materials are characterized by hardness testing and microstructure observation. The results showed that the optimum condition of hardness was produced by solution treatment temperature of 500 °C and 90 minutes holding time of 86 HRB.

Fluorimetric study of the mechanism of molecular association in aqueous solutions of polymethacrylic acid and sodium dodecylbenzenesulfonate

Science.gov (United States)

Sachko, A. V.; Zakordonskii, V. P.; Voloshinovskii, A. S.

2013-03-01

Fluorescent spectroscopy is used to investigate the processes of intermolecular association in mixed solutions of polymethacrylic acid (PMAA) and anionic sodium dodecylbenzenesulfonate (SDBS). We propose a model for describing the stage-by-stage mechanism of association processes and conclude that the nature of intermolecular associates depends on the PMAA-SDBS concentration ratio in the solution. Studying the kinetics of fluorescence decay reveals the simultaneous existence of two types of formations capable of pyrene solubilization.

Investigation of the mechanism of microplasma impact on iron and aluminum load using solutions of organic substances

International Nuclear Information System (INIS)

Lobanova, G L; Yurmazova, T A; Shiyan, L N; Voyno, D A

2015-01-01

The paper reports on the study of mechanism of electroeffects on iron and aluminum and pellets with using solutions of organic substances. Methylene blue solution, furacilin and eosin were used. It is observed the reactions of the pulse at the time and after switching off the voltage source. It is shown that there are two developing process in the conditions studied. The first process depends on material of electrodes and pulse parameters. The second process occurs spontaneously and it is determined by the redox reaction and sorption processes. The products of electrode erosion and active particles react in the redox reactions. Active particles are formed in solution by the action of pulsed electric discharge in water. The highest efficiency of the process was demonstrated on an iron pellets. (paper)

Nonextensive statistical mechanics of ionic solutions

International Nuclear Information System (INIS)

Varela, L.M.; Carrete, J.; Munoz-Sola, R.; Rodriguez, J.R.; Gallego, J.

2007-01-01

Classical mean-field Poisson-Boltzmann theory of ionic solutions is revisited in the theoretical framework of nonextensive Tsallis statistics. The nonextensive equivalent of Poisson-Boltzmann equation is formulated revisiting the statistical mechanics of liquids and the Debye-Hueckel framework is shown to be valid for highly diluted solutions even under circumstances where nonextensive thermostatistics must be applied. The lowest order corrections associated to nonadditive effects are identified for both symmetric and asymmetric electrolytes and the behavior of the average electrostatic potential in a homogeneous system is analytically and numerically analyzed for various values of the complexity measurement nonextensive parameter q

Ions, solutes and solvents, oh my!

Energy Technology Data Exchange (ETDEWEB)

Kemp, Daniel David [Iowa State Univ., Ames, IA (United States)

2009-08-01

Modern methods in ab initio quantum mechanics have become efficient and accurate enough to study many gas-phase systems. However, chemists often work in the solution phase. The presence of solvent molecules has been shown to affect reaction mechanisms1, lower reaction energy barriers2, participate in energy transfer with the solute3 and change the physical properties of the solute4. These effects would be overlooked in simple gas phase calculations. Careful study of specific solvents and solutes must be done in order to fully understand the chemistry of the solution phase. Water is a key solvent in chemical and biological applications. The properties of an individual water molecule (a monomer) and the behavior of thousands of molecules (bulk solution) are well known for many solvents. Much is also understood about aqueous microsolvation (small clusters containing ten water molecules or fewer) and the solvation characteristics when bulk water is chosen to solvate a solute. However, much less is known about how these properties behave as the cluster size transitions from the microsolvated cluster size to the bulk. This thesis will focus on species solvated with water clusters that are large enough to exhibit the properties of the bulk but small enough to consist of fewer than one hundred solvent molecules. New methods to study such systems will also be presented.

Computer simulation for precipitation process of θ (Ni3V) and γ' (Ni3Al) with microscopic phase-field method

Institute of Scientific and Technical Information of China (English)

HOU Hua; XU Hong; ZHAO Yu-hong

2006-01-01

With the microscopic phase-field model, the precipitation process of aged alloys was explored by computer simulation, which could clarify some discussional views on the precipitation mechanisms of alloys. The precipitation process of Ni75Al2.5V22.5 alloy was studied. From the simulated atomic pictures, calculated order parameters and volume fraction of different precipitates, it's found that the θ ordered phase precipitates earlier than γ' ordered phase by congruent ordering+spinodal decomposition mechanism and thus produces a nonstoicheometric θ single ordered phase. Then, the nonstoicheometric γ' phase is precipitated by a non-classical nucleation and growth mechanism at the APBS of θ phases. Meanwhile, both of them transform to stoicheometric ordered phases.

The complete information for phenomenal distributed parameter control of multicomponent chemical processes in gas, fluid and solid phase

International Nuclear Information System (INIS)

Niemiec, W.

1985-01-01

A constitutive mathematical model of distributed parameters of multicomponent chemical processes in gas, fluid and solid phase is utilized to the realization of phenomenal distributed parameter control of these processes. Original systems of partial differential constitutive state equations, in the following derivative forms /I/, /II/ and /III/ are solved in this paper from the point of view of information for phenomenal distributed parameter control of considered processes. Obtained in this way for multicomponent chemical processes in gas, fluid and solid phase: -dynamical working space-time characteristics/analytical solutions in working space-time of chemical reactors/, -dynamical phenomenal Green functions as working space-time transfer functions, -statical working space characteristics /analytical solutions in working space of chemical reactors/, -statical phenomenal Green functions as working space transfer functions, are applied, as information for realization of constitutive distributed parameter control of mass, energy and momentum aspects of above processes. Two cases are considered by existence of: A/sup o/ - initial conditions, B/sup o/ - initial and boundary conditions, for multicomponent chemical processes in gas, fluid and solid phase

Selectivity of some basic solutes on a poly(methyltetradecylsiloxane)-silica stationary phase.

Science.gov (United States)

Borges, Endler M; Collins, Carol H

2011-11-01

Complex analyses of polar compounds, especially basic ones, require more selective stationary phases. The present paper describes a stationary phase prepared by thermal immobilization of poly(methyltetradecylsiloxane) onto chromatographic silica (PMTDS-SiO(2)). This stationary phase presents hydrophobic and ion-exchange interactions that confer both high retention and unique selectivities for basic solutes. The influence of ion-exchange interactions is confirmed by the increase in retention factors of basic solutes when the mobile-phase pH changes from acidic to neutral and by the decrease in retention factors when the mobile-phase pH changes from neutral to alkaline. The ion-exchange properties of the stationary phase are enriched in neutral mobile phase (pH 7-7.5) using soft Lewis bases such as tricine and tris as buffers but are suppressed in both acidic (pH 2.5-6) and highly alkaline mobile phases (pH≤10). Increasing both temperature and flow rate permits more rapid separations while maintaining the selectivity. The stability of the stationary phase is evaluated with acid, neutral and alkaline mobile phases. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quasicrystalline phase formation in the mechanically alloyed Al{sub 70}Cu{sub 20}Fe{sub 10}

Energy Technology Data Exchange (ETDEWEB)

Medeiros, S. N. de, E-mail: snm@dfi.uem.br; Cadore, S.; Pereira, H. A.; Santos, I. A.; Colucci, C. C.; Paesano, A. [Universidade Estadual de Maringa, Departamento de Fisica (Brazil)

2010-01-15

In the present work, the formation of the Al{sub 70}Cu{sub 20}Fe{sub 10} icosahedral phase by mechanical alloying the elemental powders in a high-energy planetary mill was investigated by X-ray diffraction and Moessbauer spectroscopy. It was verified that the sample milled for 80 h produces an icosahedral phase besides Al(Cu, Fe) solid solution ({beta}-phase) and Al{sub 2}Cu intermetallic phase. The Moessbauer spectrum for this sample was fitted with a distribution of quadrupole splitting, a doublet and a sextet, revealing the presence of the icosahedral phase, {beta}-phase and {alpha}-Fe, respectively. This compound is not a good hydrogen storage. The results of the X-ray diffraction and Moessbauer spectroscopy of the sample milled for 40 h and annealed at 623 deg. C for 16 h shows essentially single i-phase and tetragonal Al{sub 7}Cu{sub 2} Fe phase.

Toughening Mechanisms in Nanolayered MAX Phase Ceramics—A Review

Directory of Open Access Journals (Sweden)

Xinhua Chen

2017-03-01

Full Text Available Advanced engineering and functional ceramics are sensitive to damage cracks, which delay the wide applications of these materials in various fields. Ceramic composites with enhanced fracture toughness may trigger a paradigm for design and application of the brittle components. This paper reviews the toughening mechanisms for the nanolayered MAX phase ceramics. The main toughening mechanisms for these ternary compounds were controlled by particle toughening, phase-transformation toughening and fiber-reinforced toughening, as well as texture toughening. Based on the various toughening mechanisms in MAX phase, models of SiC particles and fibers toughening Ti3SiC2 are established to predict and explain the toughening mechanisms. The modeling work provides insights and guidance to fabricate MAX phase-related composites with optimized microstructures in order to achieve the desired mechanical properties required for harsh application environments.

Quantum mechanical systems interacting with different polarizations of gravitational waves in noncommutative phase space

Science.gov (United States)

Saha, Anirban; Gangopadhyay, Sunandan; Saha, Swarup

2018-02-01

Owing to the extreme smallness of any noncommutative scale that may exist in nature, both in the spatial and momentum sector of the quantum phase space, a credible possibility of their detection lies in the gravitational wave (GW) detection scenario, where one effectively probes the relative length-scale variations ˜O [10-20-10-23] . With this motivation, we have theoretically constructed how a free particle and a harmonic oscillator will respond to linearly and circularly polarized gravitational waves if their quantum mechanical phase space has a noncommutative structure. We critically analyze the formal solutions which show resonance behavior in the responses of both free particle and HO systems to GW with both kind of polarizations. We discuss the possible implications of these solutions in detecting noncommutativity in a GW detection experiment. We use the currently available upper-bound estimates on various noncommutative parameters to anticipate the relative importance of various terms in the solutions. We also argue how the quantum harmonic oscillator system we considered here can be very relevant in the context of the resonant bar detectors of GW which are already operational.

Room-Temperature and Solution-Processable Cu-Doped Nickel Oxide Nanoparticles for Efficient Hole-Transport Layers of Flexible Large-Area Perovskite Solar Cells.

Science.gov (United States)

He, Qiqi; Yao, Kai; Wang, Xiaofeng; Xia, Xuefeng; Leng, Shifeng; Li, Fan

2017-12-06

Flexible perovskite solar cells (PSCs) using plastic substrates have become one of the most attractive points in the field of thin-film solar cells. Low-temperature and solution-processable nanoparticles (NPs) enable the fabrication of semiconductor thin films in a simple and low-cost approach to function as charge-selective layers in flexible PSCs. Here, we synthesized phase-pure p-type Cu-doped NiO x NPs with good electrical properties, which can be processed to smooth, pinhole-free, and efficient hole transport layers (HTLs) with large-area uniformity over a wide range of film thickness using a room-temperature solution-processing technique. Such a high-quality inorganic HTL allows for the fabrication of flexible PSCs with an active area >1 cm 2 , which have a power conversion efficiency over 15.01% without hysteresis. Moreover, the Cu/NiO x NP-based flexible devices also demonstrate excellent air stability and mechanical stability compared to their counterpart fabricated on the pristine NiO x films. This work will contribute to the evolution of upscaling flexible PSCs with a simple fabrication process and high device performances.

The Mechanical Transient Process at Asynchronous Motor Oscillating Mode

Science.gov (United States)

Antonovičs, Uldis; Bražis, Viesturs; Greivulis, Jānis

2009-01-01

The research object is squirrel-cage asynchronous motor connected to single-phase sinusoidal. There are shown, that by connecting to the stator windings a certain sequence of half-period positive and negative voltage, a motor rotor is rotated, but three times slower than in the three-phase mode. Changing the connecting sequence of positive and negative half-period voltage to stator windings, motor can work in various oscillating modes. It is tested experimentally. The mechanical transient processes had been researched in rotation and oscillating modes.

Influence aqueous solutions on the mechanical behavior of argillaceous rocks; Influence des solutions aqueuses sur le comportement mecanique des roches argileuses

Energy Technology Data Exchange (ETDEWEB)

Wakim, J

2005-12-15

The hydration of the shale with an aqueous solution induces a swelling deformation which plays an important role in the behaviour of the structures excavated in this type of grounds. This deformation is marked by a three-dimensional and anisotropic character and involves several mechanisms like adsorption, osmosis or capillarity. Several researches were dedicated to swelling and were often much debated due to the complexity of the implied phenomena. The goal of this thesis is therefore to contribute to a better understanding of shale swelling when the rock is confined and hydrated with an aqueous solution. The main part of the work accomplished was related to the Lorraine shale and to the Tournemire shale. To characterize swelling and to identify the main governing parameters, it was necessary to start the issue with an experimental approach. Many apparatus were then developed to carry out tests under various conditions of swelling. In order to facilitate the interpretation of the tests and thereafter the modelling of the behaviour, the experimental procedure adopted consisted of studying first the mechanical aspect and then the chemical aspect of swelling. In the mechanical part, swelling was studied by imposing on the sample a mechanical loading while maintaining during the tests the same aqueous solution. The principal parameters which were studied are the effect of the lateral conditions on axial swelling (impeded strain or constant stress) as well as the influence of the axial stress on radial swelling. The anisotropy of swelling was studied by carrying out, for different orientations of the sample, tests of free swelling, impeded swelling and uniaxial swelling. These various mechanical tests allowed to study the three-dimensional anisotropic swelling in all the conditions and to select the most appropriate test to be used in the second phase of the research. The precise analysis performed to explain the mechanisms behind the swelling of an argillaceous rock

Mechanisms of iodine release from iodoapatite in aqueous solution

Science.gov (United States)

Zhang, Z.; Wang, J.

2017-12-01

Immobilization of iodine-129 with waste forms in geological setting is challenging due to its extremely long half-life and high volatility in the environment. To evaluate the long-term performance of waste form, it is imperative to determine the release mechanism of iodine hosted in the waste form materials. This study investigated the iodine released from apatite structured waste form Pb9.85 (VO4)6 I1.7 to understand how diffusion and dissolution control the durability of apatite waste form. A standard semi-dynamic leach test was adopted in this study. Samples were exposed in fresh leachant periodically and the leachant was replaced after each interval. Each experiment was carried out in cap-sealed Teflon vessels under constant temperature (e.g. 90 °C). ICP-MS analysis on the reacted leachates shows that Pb and V were released constantly and congruently with the stoichiometric ratio of Pb/V. However, iodine release is incongruent and time dependent. The iodine release rate starts significantly higher than the corresponding stoichiometric value and gradually decreases, approaching the stoichiometric value. Therefore, a dual-mode mechanism is proposed to account for the iodine release from apatite, which is dominated by short-term diffusion and long-term dissolution processes. Additional tests show that the element release rates depend on a number of test parameters, including sample surface to solution volume ratio (m-1), interval (day), temperature (°C), and solution pH. This study provides a quantitative characterization of iodine release mechanism. The activation energy of iodine leaching 21±1.6 kJ/mol was obtained by varying the test temperature. At the test conditions of to neutral pH and 90 °C, the long-term iodine release rate 3.3 mg/(m2 • day) is projected by normalizing sample surface area to solution volume ratio (S/V) to 1.0 m-1 and interval to 1 day. These findings demonstrate i) the feasibility of our approach to quantify the release mechanism

Microstructure and mechanical properties of Mg-Zn-Y alloy containing LPSO phase and I-phase

Science.gov (United States)

Ye, Zhijian; Teng, Xinying; Lou, Gui; Zhou, Guorong; Leng, Jinfeng

2017-08-01

Microstructure and mechanical properties of Mg-Zn-Y alloy including LPSO phase and I-phase was investigated. Transmission electron microscopy, x-ray diffraction analysis and differential scanning calorimeter analysis reveal that the LPSO (long period stacking ordered structure) phase and I-phase can co-exist within the α-Mg matrix. Wherein, the quasicrystal phases exist in the (I-phase  +  α-Mg) eutectic structures. In the Mg-Zn-Y alloy, it is also found that 14 H type LPSO phases consist of LPSO phase and I-phase. With the addition of quasicrystal master alloy content, the microstructures are refined, and the mechanical properties are enhanced.

Novel Problem Solving - The NASA Solution Mechanism Guide

Science.gov (United States)

Keeton, Kathryn E.; Richard, Elizabeth E.; Davis, Jeffrey R.

2014-01-01

Over the past five years, the Human Health and Performance (HH&P) Directorate at the NASA Johnson Space Center (JSC) has conducted a number of pilot and ongoing projects in collaboration and open innovation. These projects involved the use of novel open innovation competitions that sought solutions from "the crowd", non-traditional problem solvers. The projects expanded to include virtual collaboration centers such as the NASA Human Health and Performance Center (NHHPC) and more recently a collaborative research project between NASA and the National Science Foundation (NSF). These novel problem-solving tools produced effective results and the HH&P wanted to capture the knowledge from these new tools, to teach the results to the directorate, and to implement new project management tools and coursework. The need to capture and teach the results of these novel problem solving tools, the HH&P decided to create a web-based tool to capture best practices and case studies, to teach novice users how to use new problem solving tools and to change project management training/. This web-based tool was developed with a small, multi-disciplinary group and named the Solution Mechanism Guide (SMG). An alpha version was developed that was tested against several sessions of user groups to get feedback on the SMG and determine a future course for development. The feedback was very positive and the HH&P decided to move to the beta-phase of development. To develop the web-based tool, the HH&P utilized the NASA Tournament Lab (NTL) to develop the software with TopCoder under an existing contract. In this way, the HH&P is using one new tool (the NTL and TopCoder) to develop the next generation tool, the SMG. The beta-phase of the SMG is planed for release in the spring of 2014 and results of the beta-phase testing will be available for the IAC meeting in September. The SMG is intended to disrupt the way problem solvers and project managers approach problem solving and to increase the

Investigations in physical mechanism of the oxidative desulfurization process assisted simultaneously by phase transfer agent and ultrasound.

Science.gov (United States)

Bhasarkar, Jaykumar B; Chakma, Sankar; Moholkar, Vijayanand S

2015-05-01

This paper attempts to discern the physical mechanism of the oxidative desulfurization process simultaneously assisted by ultrasound and phase transfer agent (PTA). With different experimental protocols, an attempt is made to deduce individual beneficial effects of PTA and ultrasound on the oxidative desulfurization system, and also the synergy between the effects of PTA and ultrasound. Effect of PTA is more marked for mechanically stirred system due to mass transfer limitations, while intense emulsification due to ultrasound helps overcome the mass transfer limitations and reduces the extent of enhancement of oxidation by PTA. Despite application of PTA and ultrasound, the intrinsic factors and properties of the reactants such as polarity (and hence partition coefficient) and diffusivity have a crucial effect on the extent of oxidation. The intrinsic reactivity of the oxidant also plays a vital role, as seen from the extent of oxidation achieved with performic acid and peracetic acid. The interfacial transport of oxidant in the form of oxidant-PTA complex reduces the undesired consumption of oxidant by the reducing species formed during transient cavitation in organic medium, which helps effective utilization of oxidant towards desulfurization. Copyright © 2014 Elsevier B.V. All rights reserved.

Mechanically Induced Graphite-Nanodiamonds-Phase Transformations During High-Energy Ball Milling

Science.gov (United States)

El-Eskandarany, M. Sherif

2017-05-01

Due to their unusual mechanical, chemical, physical, optical, and biological properties, nearly spherical-like nanodiamonds have received much attention as desirable advanced nanomaterials for use in a wide spectrum of applications. Although, nanodiamonds can be successfully synthesized by several approaches, applications of high temperature and/or high pressure may restrict the real applications of such strategic nanomaterials. Distinct from the current preparation approaches used for nanodiamonds preparation, here we show a new process for preparing ultrafine nanodiamonds (3-5 nm) embedded in a homogeneous amorphous-carbon matrix. Our process started from high-energy ball milling of commercial graphite powders at ambient temperature under normal atmospheric helium gas pressure. The results have demonstrated graphite-single wall carbon nanotubes-amorphous-carbon-nanodiamonds phase transformations carried out through three subsequent stages of ball milling. Based on XRD and RAMAN analyses, the percentage of nanodiamond phase + C60 (crystalline phase) produced by ball milling was approximately 81%, while the amorphous phase amount was 19%. The pressure generated on the powder together the with temperature increase upon the ball-powder-ball collision is responsible for the phase transformations occurring in graphite powders.

Microstructural Evolution and Mechanical Properties in Superlight Mg-Li Alloy Processed by High-Pressure Torsion

Directory of Open Access Journals (Sweden)

Qian Su

2018-04-01

Full Text Available Microstructural evolution and mechanical properties of LZ91 Mg-Li alloy processed by high-pressure torsion (HPT at an ambient temperature were researched in this paper. The microstructure analysis demonstrated that significant grain refinement was achieved after HPT processing with an average grain size reducing from 30 μm (the as-received condition to approximately 230 nm through 10 turns. X-ray diffraction analysis revealed LZ91 alloy was consisted of α phase (hexagonal close-packed structure, hcp and β phase (body-centered cubic structure, bcc before and after HPT processing. The mean value of microhardness increased with the increasing number of HPT turns. This significantly increased hardness of specimens can be explained by Hall-Petch strengthening. Simultaneously, the distribution of microhardness along the specimens was different from other materials after HPT processing due to the different mechanical properties of two different phases. The mechanical properties of LZ91 alloy processed by HPT were assessed by the micro-tensile testing at 298, 373, 423, and 473 K. The results demonstrate that the ultra-fine grain LZ91 Mg-Li alloy exhibits excellent mechanical properties: tensile elongation is approximately 400% at 473 K with an initial strain rate of 1 × 10−2 s−1.

Process for preparation of a solid-phase radioimmunoassay support and use thereof

International Nuclear Information System (INIS)

Meriadec, B.; Roubertie, P.

1979-01-01

A process is described for the preparation of a support useful in radioimmunoassay chromatographic columns. The process involves the preparation of a chromatographic gel capable of selectively retaining one or more components contained in an antigen-antibody-containing solution. The gel is bound to the appropriate antiserum, then freeze-dried, pulverized and compressed into a tablet. The tablet support swells upon contact with an antigen-antibody-containing solution to conform to the shape of the columns. An example of the application of this support in the radioimmunoassay of thyroid-stimulating hormone is described. This type of support is also particularly useful in second antibody solid phase radioimmunoassays since there is no limit to the size of the antigen to which this technology may be applied. (U.K.)

The Colloidal Stabilization of Quantum Dots: Towards Manufacturable, Efficient Solution-Processed Solar Cells

Science.gov (United States)

Rollny, Lisa

Understanding colloidal stabilization can influence the design of optoelectronic devices and enable improvements to their performance and stability. For photovoltaics, important characteristics of the active layer material are high conductivity along with a minimum of recombination centers. In order to capitalize on the benefits of solution-processed materials, it is important to minimize the number of processing steps: ideally, to achieve a low-cost solution, materials would be deposited using a single process step compatible with roll-to-roll manufacturing. Prior to this work, the highest-performing colloidal quantum dots (CQD) solar cells have relied on several deposition steps that are repeated in a layer-by-layer (LBL) fashion. The purpose of these process steps has been to remove the long insulating ligands used in synthesis and replace them with short ligands that allow electrical conduction. The large number of steps combined, typically implemented via spin coating, leads to inefficient materials utilization and fails to show a path to a manufacturable solution. In this work, the first CQD solar cells were designed, built, and characterized combining state-of-art performance with scalable manufacture. Firstly, I report the first automated CQD synthesis to result in CQDs that form high-performance CQD solar cells. I analyze the CQD synthesis and by separating it into two phases---nucleation and growth phase---my insights are used to create higher-quality CQDs exhibiting enhanced monodispersity. I then proceed to develop a CQD ink: a CQD solution ready for direct deposition to form a semiconducting film exhibiting low trap state density. In early trials the CQD ink showed only limited power conversion efficiencies of 2%. I designed a new ink strategy, which I term cleavable hemiketal ligands. This novel two-component ligand strategy enables the combination of colloidal stabilization (via this longer two-component ligand) and cleavability (enabling excellent

Comprehensive Peptide Ion Structure Studies Using Ion Mobility Techniques: Part 3. Relating Solution-Phase to Gas-Phase Structures.

Science.gov (United States)

Kondalaji, Samaneh Ghassabi; Khakinejad, Mahdiar; Valentine, Stephen J

2018-06-01

Molecular dynamics (MD) simulations have been utilized to study peptide ion conformer establishment during the electrospray process. An explicit water model is used for nanodroplets containing a model peptide and hydronium ions. Simulations are conducted at 300 K for two different peptide ion charge configurations and for droplets containing varying numbers of hydronium ions. For all conditions, modeling has been performed until production of the gas-phase ions and the resultant conformers have been compared to proposed gas-phase structures. The latter species were obtained from previous studies in which in silico candidate structures were filtered according to ion mobility and hydrogen-deuterium exchange (HDX) reactivity matches. Results from the present study present three key findings namely (1) the evidence from ion production modeling supports previous structure refinement studies based on mobility and HDX reactivity matching, (2) the modeling of the electrospray process is significantly improved by utilizing initial droplets existing below but close to the calculated Rayleigh limit, and (3) peptide ions in the nanodroplets sample significantly different conformers than those in the bulk solution due to altered physicochemical properties of the solvent. Graphical Abstract ᅟ.

Rirang uranium ore processing: continuous solvent extraction of uranium from Rirang ore acid digestion solution

International Nuclear Information System (INIS)

Riza, F.; Nuri, H. L.; Waluya, S.; Subijanto, A.; Sarono, B.

1998-01-01

Separation of uranium from Rirang ore acid digestion solution by means of continuous solvent extraction using mixer-settlers has been studied and a mixture of 0.3 M D2EHPA and 0.075 M TOPO extracting agent and kerosene diluent is employed to recover and separate uranium from Th, RE, phosphate containing solution. The experiments have been conducted batch-wise and several parameters have been studied including the aqueous to organic phase ratio, A/O, the extraction and the stripping times, and the operation temperature. The optimum conditions for extraction have been found to be A/O = 2 ratio, five minute extraction time per stage at room temperature. The uranium recovery of 99.07% has been achieved at those conditions whilst U can be stripped from the organic phase by 85% H 3 PO 4 solution with an O/A = 1 for 5 minutes stripping time per stage, and in a there stage operation at room temperature yielding a 100% uranium recovery from the stripping process

Kinetic process of mechanical alloying in Fe50Cu50

DEFF Research Database (Denmark)

Huang, J.Y.; Jiang, Jianzhong; Yasuda, H.

1998-01-01

It is shown that mechanical alloying in the immiscible Fe-Cu system is governed by the atomic shear event and shear-induced diffusion process. We found that an alpha-to-gamma phase transformation, as evidenced by the Nishiyama-Wasserman orientation relationship, occurs by simultaneous shearing...

Simulating mixed-phase Arctic stratus clouds: sensitivity to ice initiation mechanisms

Directory of Open Access Journals (Sweden)

G. McFarquhar

2009-07-01

Full Text Available The importance of Arctic mixed-phase clouds on radiation and the Arctic climate is well known. However, the development of mixed-phase cloud parameterization for use in large scale models is limited by lack of both related observations and numerical studies using multidimensional models with advanced microphysics that provide the basis for understanding the relative importance of different microphysical processes that take place in mixed-phase clouds. To improve the representation of mixed-phase cloud processes in the GISS GCM we use the GISS single-column model coupled to a bin resolved microphysics (BRM scheme that was specially designed to simulate mixed-phase clouds and aerosol-cloud interactions. Using this model with the microphysical measurements obtained from the DOE ARM Mixed-Phase Arctic Cloud Experiment (MPACE campaign in October 2004 at the North Slope of Alaska, we investigate the effect of ice initiation processes and Bergeron-Findeisen process (BFP on glaciation time and longevity of single-layer stratiform mixed-phase clouds. We focus on observations taken during 9–10 October, which indicated the presence of a single-layer mixed-phase clouds. We performed several sets of 12-h simulations to examine model sensitivity to different ice initiation mechanisms and evaluate model output (hydrometeors' concentrations, contents, effective radii, precipitation fluxes, and radar reflectivity against measurements from the MPACE Intensive Observing Period. Overall, the model qualitatively simulates ice crystal concentration and hydrometeors content, but it fails to predict quantitatively the effective radii of ice particles and their vertical profiles. In particular, the ice effective radii are overestimated by at least 50%. However, using the same definition as used for observations, the effective radii simulated and that observed were more comparable. We find that for the single-layer stratiform mixed-phase clouds simulated, process

Simulating mixed-phase Arctic stratus clouds: sensitivity to ice initiation mechanisms

Science.gov (United States)

Sednev, I.; Menon, S.; McFarquhar, G.

2009-07-01

The importance of Arctic mixed-phase clouds on radiation and the Arctic climate is well known. However, the development of mixed-phase cloud parameterization for use in large scale models is limited by lack of both related observations and numerical studies using multidimensional models with advanced microphysics that provide the basis for understanding the relative importance of different microphysical processes that take place in mixed-phase clouds. To improve the representation of mixed-phase cloud processes in the GISS GCM we use the GISS single-column model coupled to a bin resolved microphysics (BRM) scheme that was specially designed to simulate mixed-phase clouds and aerosol-cloud interactions. Using this model with the microphysical measurements obtained from the DOE ARM Mixed-Phase Arctic Cloud Experiment (MPACE) campaign in October 2004 at the North Slope of Alaska, we investigate the effect of ice initiation processes and Bergeron-Findeisen process (BFP) on glaciation time and longevity of single-layer stratiform mixed-phase clouds. We focus on observations taken during 9-10 October, which indicated the presence of a single-layer mixed-phase clouds. We performed several sets of 12-h simulations to examine model sensitivity to different ice initiation mechanisms and evaluate model output (hydrometeors' concentrations, contents, effective radii, precipitation fluxes, and radar reflectivity) against measurements from the MPACE Intensive Observing Period. Overall, the model qualitatively simulates ice crystal concentration and hydrometeors content, but it fails to predict quantitatively the effective radii of ice particles and their vertical profiles. In particular, the ice effective radii are overestimated by at least 50%. However, using the same definition as used for observations, the effective radii simulated and that observed were more comparable. We find that for the single-layer stratiform mixed-phase clouds simulated, process of ice phase initiation

Exploration of Doubly Thermal Phase Transition Process of PDEGA-b-PDMA-b-PVCL in Water.

Science.gov (United States)

Ye, Zhangxin; Li, Youcheng; An, Zesheng; Wu, Peiyi

2016-07-05

Understanding of phase transition mechanism of thermoresponsive polymers is the basis for the rational design of smart materials with predictable properties. Linear ABC triblock terpolymer poly(di(ethylene glycol)ethyl ether acrylate)-b-poly(N,N-dimethylacrylamide)-b-poly(N-vinylcaprolactam) (PDEGA-b-PDMA-b-PVCL) was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. The doubly thermal phase transition of PDEGA-b-PDMA-b-PVCL in aqueous solution was investigated by a combination of nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), turbidimetry, and dynamic light scattering (DLS). The terpolymer self-assembles into micelles with PDEGA being the core-forming block during the first lower critical solution temperature (LCST) transition corresponding to PDEGA, which is followed by a second LCST transition corresponding to PVCL, resulting in the formation of micellar aggregates. The PDMA middle segment plays an important role as an isolation zone to prevent cooperative dehydration of the PDEGA and PVCL segments, and therefore, two independent LCST transitions corresponding to PDEGA and PVCL were observed. Furthermore, FT-IR with perturbation correlation moving window (PCMW) and two-dimensional spectroscopy (2DCOS) was applied to elucidate the two-step phase transition mechanism of this terpolymer. It was observed that the CH, ester carbonyl, and ether groups of PDEGA change prior to the CH and amide carbonyl groups of PVCL, further supporting that the two phase transitions corresponding to PDEGA and PVCL indeed occur without mutual interferences.

Anodic processes in the chemical and electrochemical etching of Si crystals in acid-fluoride solutions: Pore formation mechanism

Energy Technology Data Exchange (ETDEWEB)

Ulin, V. P.; Ulin, N. V.; Soldatenkov, F. Yu., E-mail: f.soldatenkov@mail.ioffe.ru [Ioffe Physical–Technical Institute (Russian Federation)

2017-04-15

The interaction of heavily doped p- and n-type Si crystals with hydrofluoric acid in the dark with and without contact with metals having greatly differing work functions (Ag and Pd) is studied. The dependences of the dissolution rates of Si crystals in HF solutions that contain oxidizing agents with different redox potentials (FeCl{sub 3}, V{sub 2}O{sub 5} and CrO{sub 3}) on the type and level of silicon doping are determined. Analysis of the experimental data suggests that valence-band holes in silicon are not directly involved in the anodic reactions of silicon oxidation and dissolution and their generation in crystals does not limit the rate of these processes. It is also shown that the character and rate of the chemical process leading to silicon dissolution in HF-containing electrolytes are determined by the interfacial potential attained at the semiconductor–electrolyte interface. The mechanism of electrochemical pore formation in silicon crystals is discussed in terms of selfconsistent cooperative reactions of nucleophilic substitution between chemisorbed fluorine anions and coordination- saturated silicon atoms in the crystal subsurface layer. A specific feature of these reactions for silicon crystals is that vacant nonbonding d{sup 2}sp{sup 3} orbitals of Si atoms, associated with sixfold degenerate states corresponding to the Δ valley of the conduction band, are involved in the formation of intermediate complexes. According to the suggested model, the pore-formation process spontaneously develops in local regions of the interface under the action of the interfacial potential in the adsorption layer and occurs as a result of the detachment of (SiF{sub 2}){sub n} polymer chains from the crystal. Just this process leads to the preferential propagation of pores along the <100> crystallographic directions. The thermodynamic aspects of pore nucleation and the effect of the potential drop across the interface, conduction type, and free-carrier concentration

Phase transformation and mechanical behavior of thermomechanically controlled processed high strength ordnance steel

International Nuclear Information System (INIS)

Bandyopadhyay, P.S.; Ghosh, S.K.; Kundu, S.; Chatterjee, S.

2013-01-01

A new low carbon titanium and niobium microalloyed steel has been thermomechanically processed in a pilot plant unit. Phase transformation phenomenon of the above steel during continuous cooling has been assessed. Evolution of microstructure and mechanical properties has also been studied at different finish rolling temperatures. A mixture of intragranular ferrite with granular bainite and bainitic ferrite along with inter-lath and intra-lath precipitation of (Ti, Nb)CN particles are the characteristic microstructural feature of air cooled steel. However, mixture of lower bainite and lath martensitic structure along with similar type (Ti, Nb)CN precipitate is observed in water quenched steel. High yield strength (896–948 MPa) with high tensile strength (974–1013 MPa) has been achieved with moderate ductility (16–17%) for the selected range of finish rolling temperature for air cooled steel. However, the water quenched steel yields higher yield strength (1240–1260 MPa) as well as higher tensile strength (1270–1285 MPa) but with lower ductility (13–14%) for the selected range of finish rolling temperature. Fairly good impact toughness values in the range of 50–89 J are obtained for the air cooled steel which are marginally higher than those of water quenched steel (42–81 J). - Highlights: ► New high strength steel has been processed in a pilot plant scale. ► Primarily granular bainite and bainitic ferrite are obtained in air cooled steel. ► Mixture of lower bainite and lath martensite is obtained in water quenched steel. ► (Ti, Nb)CN precipitate is obtained for both air cooled and water quenched steels. ► Highest strength with reasonable ductility has been achieved after water quenching

Phase transformation and mechanical behavior of thermomechanically controlled processed high strength ordnance steel

Energy Technology Data Exchange (ETDEWEB)

Bandyopadhyay, P.S. [Ordnance Development Centre, Metal and Steel Factory, Ishapore 743 144 (India); Ghosh, S.K., E-mail: skghosh@metal.becs.ac.in [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur, Howrah 711 103 (India); Kundu, S.; Chatterjee, S. [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur, Howrah 711 103 (India)

2013-02-15

A new low carbon titanium and niobium microalloyed steel has been thermomechanically processed in a pilot plant unit. Phase transformation phenomenon of the above steel during continuous cooling has been assessed. Evolution of microstructure and mechanical properties has also been studied at different finish rolling temperatures. A mixture of intragranular ferrite with granular bainite and bainitic ferrite along with inter-lath and intra-lath precipitation of (Ti, Nb)CN particles are the characteristic microstructural feature of air cooled steel. However, mixture of lower bainite and lath martensitic structure along with similar type (Ti, Nb)CN precipitate is observed in water quenched steel. High yield strength (896–948 MPa) with high tensile strength (974–1013 MPa) has been achieved with moderate ductility (16–17%) for the selected range of finish rolling temperature for air cooled steel. However, the water quenched steel yields higher yield strength (1240–1260 MPa) as well as higher tensile strength (1270–1285 MPa) but with lower ductility (13–14%) for the selected range of finish rolling temperature. Fairly good impact toughness values in the range of 50–89 J are obtained for the air cooled steel which are marginally higher than those of water quenched steel (42–81 J). - Highlights: ► New high strength steel has been processed in a pilot plant scale. ► Primarily granular bainite and bainitic ferrite are obtained in air cooled steel. ► Mixture of lower bainite and lath martensite is obtained in water quenched steel. ► (Ti, Nb)CN precipitate is obtained for both air cooled and water quenched steels. ► Highest strength with reasonable ductility has been achieved after water quenching.

EXAFS Phase Retrieval Solution Tracking for Complex Multi-Component System: Synthesized Topological Inverse Computation

International Nuclear Information System (INIS)

Lee, Jay Min; Yang, Dong-Seok; Bunker, Grant B

2013-01-01

Using the FEFF kernel A(k,r), we describe the inverse computation from χ(k)-data to g(r)-solution in terms of a singularity regularization method based on complete Bayesian statistics process. In this work, we topologically decompose the system-matched invariant projection operators into two distinct types, (A + AA + A) and (AA + AA + ), and achieved Synthesized Topological Inversion Computation (STIC), by employing a 12-operator-closed-loop emulator of the symplectic transformation. This leads to a numerically self-consistent solution as the optimal near-singular regularization parameters are sought, dramatically suppressing instability problems connected with finite precision arithmetic in ill-posed systems. By statistically correlating a pair of measured data, it was feasible to compute an optimal EXAFS phase retrieval solution expressed in terms of the complex-valued χ(k), and this approach was successfully used to determine the optimal g(r) for a complex multi-component system.

Can slow-diffusing solute atoms reduce vacancy diffusion in advanced high-temperature alloys?

International Nuclear Information System (INIS)

Goswami, Kamal Nayan; Mottura, Alessandro

2014-01-01

The high-temperature mechanical properties of precipitate-strengthened advanced alloys can be heavily influenced by adjusting chemical composition. The widely-accepted argument within the community is that, under certain temperature and loading conditions, plasticity occurs only in the matrix, and dislocations have to rely on thermally-activated climb mechanisms to overcome the barriers to glide posed by the hard precipitates. This is the case for γ′-strengthened Ni-based superalloys. The presence of dilute amounts of slow-diffusing solute atoms, such as Re and W, in the softer matrix phase is thought to reduce plasticity by retarding the climb of dislocations at the interface with the hard precipitate phase. One hypothesis is that the presence of these solutes must hinder the flow of vacancies, which are essential to the climb process. In this work, density functional theory calculations are used to inform two analytical models to describe the effect of solute atoms on the diffusion of vacancies. Results suggest that slow-diffusing solute atoms are not effective at reducing the diffusion of vacancies in these systems

The effects of processing conditions on the surface morphology and hydrophobicity of polyvinylidene fluoride membranes prepared via vapor-induced phase separation

Science.gov (United States)

Peng, Yuelian; Fan, Hongwei; Ge, Ju; Wang, Shaobin; Chen, Ping; Jiang, Qi

2012-12-01

The present investigation reveals how the surface morphology and the hydrophobicity of polyvinylidene fluoride (PVDF) membranes, which were prepared via a vapor-induced phase separation method, were affected by the initial PVDF content in the casting solution and the air temperature. The surface morphology was characterized with scanning electron microscopy. A ternary phase diagram of PVDF/N, N-dimethylacetamide/water was constructed to explain the formation mechanism of the different morphologies. The results show that different membrane morphologies and hydrophobicities can be obtained by changing the processing conditions. Low air temperature and high PVDF contents facilitate the crystallization process, resulting in the formation of a porous skin and particle morphology, which increases the hydrophobicity of the surface. High air temperature and low PVDF contents are favorable for the formation of a net-like surface morphology via spinodal decomposition and lead to a superhydrophobic surface. Theoretical calculations were performed to testify that the net-like surface was more favorable for superhydrophobicity than the particle-based surface.

Exact solution of the hidden Markov processes

Science.gov (United States)

Saakian, David B.

2017-11-01

We write a master equation for the distributions related to hidden Markov processes (HMPs) and solve it using a functional equation. Thus the solution of HMPs is mapped exactly to the solution of the functional equation. For a general case the latter can be solved only numerically. We derive an exact expression for the entropy of HMPs. Our expression for the entropy is an alternative to the ones given before by the solution of integral equations. The exact solution is possible because actually the model can be considered as a generalized random walk on a one-dimensional strip. While we give the solution for the two second-order matrices, our solution can be easily generalized for the L values of the Markov process and M values of observables: We should be able to solve a system of L functional equations in the space of dimension M -1 .

Welding thermal cycle-triggered precipitation processes in steel S700MC subjected to the thermo-mechanical control processing

OpenAIRE

Górka J.

2017-01-01

This study presents tests concerned with welding thermal process-induced precipitation processes taking place in 10 mm thick steel S700MC subjected to the Thermo-Mechanical Control Process (TMCP) with accelerated cooling. The thermomechanical processing of steel S700MC leads to its refinement, structural defects and solutioning with hardening constituents. Tests of thin foils performed using a transmission electron microscope revealed that the hardening of steel S700MC was primarily caused by...

Phase Transformation Behavior of Oxide Particles Formed in Mechanically Alloyed Fe-5Y{sub 2}O{sub 3} Powder

Energy Technology Data Exchange (ETDEWEB)

Kim, Ga Eon; Choi, Jung-Sun; Noh, Sanghoon; Kang, Suk Hoon; Choi, Byoung Kwon; Kim, Tae Kyu [Korea Atomic Energy Research Institute, Deajeon (Korea, Republic of); Kim, Young Do [Hanyang University, Seoul (Korea, Republic of)

2017-05-15

The phase transformation behavior of the oxides formed in mechanically alloyed Fe-5Y{sub 2}O{sub 3} powder is investigated. Non-stoichiometric Y-rich and Fe-rich oxides with sizes of less than 300 nm are observed in the mechanically alloyed powder. The diffusion and redistribution reactions of the elements in these oxides during heating of the powder above 800 ℃ were observed, and these reactions result in the formation of a Y{sub 3}Fe{sub 5}O{sub 12} phase after heating at 1050 ℃. Thus, it is considered that the Y{sub 2}O{sub 3} powder and some Fe powder are formed from the non-stoichiometric Y-rich and Fe-rich oxides after the mechanical alloying process, and a considerable energy accumulated during the mechanical alloying process leads to a phase transformation of the Y-rich and Fe-rich oxides to Y{sub α}Fe{sub β}O{sub γ}-type phase during heating.

KDP Aqueous Solution-in-Oil Microemulsion for Ultra-Precision Chemical-Mechanical Polishing of KDP Crystal

Directory of Open Access Journals (Sweden)

Hui Dong

2017-03-01

Full Text Available A novel functional KH2PO4 (KDP aqueous solution-in-oil (KDP aq/O microemulsion system for KDP crystal ultra-precision chemical-mechanical polishing (CMP was prepared. The system, which consisted of decanol, Triton X-100, and KH2PO4 aqueous solution, was available at room temperature. The functional KDP aq/O microemulsion system was systematically studied and applied as polishing solution to KDP CMP technology. In this study, a controlled deliquescent mechanism was proposed for KDP polishing with the KDP aq/O microemulsion. KDP aqueous solution, the chemical etchant in the polishing process, was caged into the micelles in the microemulsion, leading to a limitation of the reaction between the KDP crystal and KDP aqueous solution only if the microemulsion was deformed under the effect of the external force. Based on the interface reaction dynamics, KDP aqueous solutions with different concentrations (cKDP were applied to replace water in the traditional water-in-oil (W/O microemulsion. The practicability of the controlled deliquescent mechanism was proved by the decreasing material removal rate (MRR with the increasing of the cKDP. As a result, the corrosion pits on the KDP surface were avoided to some degree. Moreover, the roughnesses of KDP with KDP aq/O microemulsion (cKDP was changed from 10 mM to 100 mM as polishing solutions were smaller than that with the W/O microemulsion. The smallest surface root-mean-square roughness of 1.5 nm was obtained at a 30 mmol/L KDP aq solution, because of the most appropriate deliquescent rate and MRR.

The effect warming time of mechanical properties and structural phase aluminum alloy nickel

International Nuclear Information System (INIS)

Husna Al Hasa, M.; Anwar Muchsin

2011-01-01

Ferrous aluminum alloys as fuel cladding will experience the process of heat treatment above the recrystallization temperature. Temperature and time of heat treatment will affect the nature of the metal. Heating time allows will affect change in mechanical properties, thermal and structure of the metal phase. This study aims to determine the effect of time of heat treatment on mechanical properties and phase metal alloys. Testing the mechanical properties of materials, especially violence done by the method of Vickers. Observation of microstructural changes made by metallographic-optical and phase structure were analyzed Based on the x-ray diffraction patterns Elemental analysis phase alloy compounds made by EDS-SEM. Test results show the nature of violence AlFeNiMg alloy by heating at 500°C with a warm-up time 1 hour, 2 hours and 3 hours respectively decreased range 94.4 HV, 87.6 HV and 85.1 HV. The nature of violence AlFeNi alloy showed a decrease in line with the longer heating time. Metallographic-optical observations show the microstructural changes with increasing heating time. Microstructure shows the longer the heating time trend equi axial shaped grain structure of growing and the results showed a trend analyst diffraction pattern formation and phase θ α phase (FeAl3) in the alloy. (author)

Purification of inkjet ink from water using liquid phase, electric discharge polymerization and cellulosic membrane filtration.

Science.gov (United States)

Jordan, Alexander T; Hsieh, Jeffery S; Lee, Daniel T

2013-01-01

A method to separate inkjet ink from water was developed using a liquid phase, electric discharge process. The liquid phase, electric discharge process with filtration or sedimentation was shown to remove 97% of inkjet ink from solutions containing between 0.1-0.8 g/L and was consistent over a range of treatment conditions. Additionally, particle size analysis of treated allyl alcohol and treated propanol confirmed the electric discharge treatment has a polymerization mechanism, and small molecule analysis of treated methanol using gas chromatography and mass spectroscopy confirmed the mechanism was free radical initiated polymerization.

Mechanism for suppression of radiation-induced segregation by oversized solute addition in austenitic stainless steel

Science.gov (United States)

Hackett, Micah Jeremiah

precipitate surfaces on the time scales of proton irradiations, and (2) atom probe measurements confirmed the loss of oversized solute in solution as a function of irradiation dose. RIS measurements and subsequent analyses were consistent with the solute-vacancy trapping process as the mechanism for enhanced recombination and suppression of RIS.

The first preparative solution phase synthesis of melanotan II

Directory of Open Access Journals (Sweden)

2008-10-01

Full Text Available Melanotan II is a synthetic cyclic heptapeptide used to prevent a sunlight-induced skin cancer by stimulating the skin tanning process. In this paper we report the first solution phase synthesis of the title compound. The hexapeptide sequence has been assembled by [(2+2+1+1] scheme. After removing the orthogonal protection, a carbodiimide mediated lactamization, involving the ε-amino group of lysine and γ-carboxy group of aspartic acid, led to a cyclic intermediate. Appending N-acetylnorleucine concluded the assembly of melanotan II molecule. Protection of the lateral groups in arginine and tryptophan was omitted for atom and step economy reasons. The total synthesis of melanotan II was accomplished in 12 steps with 2.6% overall yield, affording >90% pure peptide without using preparative chromatography.

Investigation of electrochemical corrosion behavior in a 3.5 wt.% NaCl solution of boronized dual-phase steel

International Nuclear Information System (INIS)

Kayali, Yusuf; Anaturk, Bilal

2013-01-01

Highlights: ► Corrosion behaviors in a 3.5% NaCl solution of boronized Dual-Phase (DP) steels were examined. ► The martensite ratio increased with an increase in the intercritical annealing temperature. ► The corrosion resistance decreased with increase of the martensite ratio. ► The boride layer increased the corrosion resistance of DP steel 2–3-fold. ► The superior properties of DP steel as well as poor corrosion properties were improved by the boriding process. - Abstract: In this study, corrosion behaviors of boronized and non-boronized dual-phase steel were investigated with Tafel extrapolation and linear polarization methods in a 3.5 wt.% NaCl solution. Microstructure analyses show that the boride layer on the dual-phase steel surface had a flat and saw smooth morphology. It was detected by X-ray diffraction (XRD) analysis that the boride layer contained FeB and Fe 2 B phases. The amount of martensite increases with an increase in the intercritical annealing temperature. Both the amount of martensite and the morphology of the phase constituents have an influence on the corrosion behavior of dual-phase steel. A higher corrosion tendency was observed with an increased amount of martensite. The corrosion resistance of boronized dual-phase steel is higher compared with that of dual-phase steel

Crud treatment with 3 phase centrifuge in heap leach uranium process

International Nuclear Information System (INIS)

Hartmann, T.

2010-01-01

The presence of crud represents a permanent challenge for solvent extraction in the hydro-metal Uranium industry. The crud forms in the settlers of SX extraction. The crud is a stable emulsion which slowly spreads along the phase boundary between the aqueous and organic phase. Spreading of this intermediate phase is determined by the following influencing factors. Wind blows dust into the open settlers, some suspended solids coming with the pregnant leach solution (PLS) and wrong design of the mixers cause stable emulsions. Metallic solid residue is likewise responsible for the growth rate of the crud at the above-mentioned phase boundary. The crud can significantly impair the efficiency of hydro-metal extraction because the phase boundary between the aqueous and organic phases assumes substantial proportions, and the settlers cannot react flexibly. In a chain reaction, all settlers connected in series become infected with crud. The transfer of organic phase to the electrowinning (EW) cell can cause 'cathode burn'. The entrainment of electrolyte into the extraction stage can result in loss of pH control in the extraction circuit which will cause a drop in extraction efficiency. On the other hand, entrainment of the organic in the raffinate will result in organic losses to the leach circuit. Continuous treatment of the crud is extremely effective and reliable with a 3-phase separating solid bowl centrifuge. All three phases are separated distinctly from one another. All associated process steps exhibit a steady uniform efficiency. The main benefit for the customer is that process fluctuations in the extraction process will no longer occur. The 3-phase separating solid bowl centrifuge consists of an axial solid-wall bowl. The solid-wall bowl has a cylindrical section for simultaneous separation and clarification of the aqueous and organic liquid phase and a conical section for efficient solids dewatering. The 3-phase feed suspension is fed into the solid bowl

Sampling Molecular Conformers in Solution with Quantum Mechanical Accuracy at a Nearly Molecular-Mechanics Cost.

Science.gov (United States)

Rosa, Marta; Micciarelli, Marco; Laio, Alessandro; Baroni, Stefano

2016-09-13

We introduce a method to evaluate the relative populations of different conformers of molecular species in solution, aiming at quantum mechanical accuracy, while keeping the computational cost at a nearly molecular-mechanics level. This goal is achieved by combining long classical molecular-dynamics simulations to sample the free-energy landscape of the system, advanced clustering techniques to identify the most relevant conformers, and thermodynamic perturbation theory to correct the resulting populations, using quantum-mechanical energies from density functional theory. A quantitative criterion for assessing the accuracy thus achieved is proposed. The resulting methodology is demonstrated in the specific case of cyanin (cyanidin-3-glucoside) in water solution.

Quantifying Quantum-Mechanical Processes.

Science.gov (United States)

Hsieh, Jen-Hsiang; Chen, Shih-Hsuan; Li, Che-Ming

2017-10-19

The act of describing how a physical process changes a system is the basis for understanding observed phenomena. For quantum-mechanical processes in particular, the affect of processes on quantum states profoundly advances our knowledge of the natural world, from understanding counter-intuitive concepts to the development of wholly quantum-mechanical technology. Here, we show that quantum-mechanical processes can be quantified using a generic classical-process model through which any classical strategies of mimicry can be ruled out. We demonstrate the success of this formalism using fundamental processes postulated in quantum mechanics, the dynamics of open quantum systems, quantum-information processing, the fusion of entangled photon pairs, and the energy transfer in a photosynthetic pigment-protein complex. Since our framework does not depend on any specifics of the states being processed, it reveals a new class of correlations in the hierarchy between entanglement and Einstein-Podolsky-Rosen steering and paves the way for the elaboration of a generic method for quantifying physical processes.

Theory of the thermodynamic influence of solution-phase additives in shape-controlled nanocrystal synthesis.

Science.gov (United States)

Qi, Xin; Fichthorn, Kristen A

2017-10-19

Though many experimental studies have documented that certain solution-phase additives can play a key role in the shape-selective synthesis of metal nanocrystals, the origins and mechanisms of this shape selectivity are still unclear. One possible role of such molecules is to thermodynamically induce the equilibrium shape of a nanocrystal by altering the interfacial free energies of the facets. Using a multi-scheme thermodynamic integration method that we recently developed [J. Chem. Phys., 2016, 145, 194108], we calculate the solid-liquid interfacial free energies γ sl and investigate the propensity to achieve equilibrium shapes in such syntheses. We first apply this method to Ag(100) and Ag(111) facets in ethylene glycol solution containing polyvinylpyrrolidone (PVP), to mimic the environment in polyol synthesis of Ag nanocrystals. We find that although PVP has a preferred binding to Ag(100), its selectivity is not sufficient to induce a thermodynamic preference for {100}-faceted nanocubes, as has been observed experimentally. This indicates that PVP promotes Ag nanocube formation kinetically rather than thermodynamically. We further quantify the thermodynamic influence of adsorbed solution-phase additives for generic molecules, by building a γ sl ratio/nanocrystal shape map as a function of zero-temperature binding energies. This map can be used to gauge the efficacy of candidate additive molecules for producing targeted thermodynamic nanocrystal shapes. The results indicate that only additives with a strong facet selectivity can impart significant thermodynamic-shape change. Therefore, many of the nanocrystals observed in experiments are likely kinetic products.

Direct methods of solution for problems in mechanics from invariance principles

International Nuclear Information System (INIS)

Rajan, M.

1986-01-01

Direct solutions to problems in mechanics are developed from variational statements derived from the principle of invariance of the action integral under a one-parameter family of infinitesimal transformations. Exact, direct solution procedures for linear systems are developed by a careful choice of the arbitrary functions used to generate the infinitesimal transformations. It is demonstrated that the well-known methods for the solution of differential equations can be directly adapted to the required variational statements. Examples in particle and continuum mechanics are presented

[Mechanism of gold solid extraction from aurocyanide solution using D3520 resin impregnated with TRPO].

Science.gov (United States)

Yang, Xiang-Jun; Wang, Shi-Xiong; Zou, An-Qin; Chen, Jing; Guo, Hong

2014-02-01

Trialkyphosphine oxides (TRPO) was successfully used for the impregnation of D3520 resin to prepare an extractant-impregnated resin (EIR). Solid extraction of Au(I) from alkaline cyanide solution was studied using this extractant-impregnated resin (EIR), with addition of cetyltrimethylammonium bromide (CTMAB), directly into the aurous aqueous phase in advance. The mechanism of solid extraction was further investigated by means of FTIR, XPS and SEM. The column separation studies have shown that cationic surfactant CTMAB played a key role in the solid phase extraction, and the resin containing TRPO were effective for the extraction of gold when the molar ratio of CTMAB: Au( I ) reached 1:1. FTIR spectroscopy of gold loaded EIR showed that the frequency of C[triple bond]N stretching vibration was at 2144 cm(-1), and the frequency of P=O stretching vibration shifted to lower frequency from 1153 to 1150 cm(-1). The XPS spectrum of N(1s), Au(4f7/2) and Au(4f5/2) sugges- ted that the coordination environment of gold did not change before and after extraction, and gold was still as the form of Au (CN)2(-) anion exiting in the loaded resin; O(1s) spectrum showed that the chemically combined water significantly increased after solid extraction from 30.74% to 42.34%; Comparing to the P(2p) spectrum before and after extraction, the binding energy increased from 132. 15 to 132. 45 eV, indicating there maybe existing hydrogen-bond interaction between P=O and water molecule, such as P=O...H-O-H. The above results obtained established that in the solid extraction process, the hydrophobic ion association [CTMA+ x Au(CN)] diffused from the bulk solution into the pores of the EIR, and then be solvated by TRPO adsorbed in the pores through hydrogen bonding bridged by the water molecules.

GaN Bulk Growth and Epitaxy from Ca-Ga-N Solutions, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — This SBIR proposal addresses the liquid phase epitaxy (LPE) of gallium nitride (GaN) films using nitrogen-enriched metal solutions. Growth of GaN from solutions...

Growth mechanism and magnetism in carbothermal synthesized Fe{sub 3}O{sub 4} nanoparticles from solution combustion precursors

Energy Technology Data Exchange (ETDEWEB)

Wang, Xuanli [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083 China (China); Qin, Mingli, E-mail: qinml@mater.ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083 China (China); Cao, Zhiqin [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083 China (China); School of Materials Science and Engineering, Pan Zhihua University, Pan Zhihua, 617000 China (China); Jia, Baorui; Gu, Yueru; Qu, Xuanhui [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083 China (China); Volinsky, Alex A. [Department of Mechanical Engineering, University of South Florida, Tampa, 33620 (United States)

2016-12-15

Magnetic Fe{sub 3}O{sub 4} nanoparticles were prepared by carbothermal reduction using solution combustion synthesis precursors derived from ferric nitrate (oxidizer), glycine (fuel) and glucose (carbon source) mixed solution. In this paper, the growth mechanism and magnetism in Fe{sub 3}O{sub 4} nanoparticles were investigated by adjusting the glucose content in precursor and the heat temperature in carbothermal process. The products were analyzed by X-ray diffraction, Field emission scanning electron microscopy, Infrared adsorption method and Vibrating sample magnetometry. The results revealed that the more amount of glucose, the earlier Fe{sub 3}O{sub 4} phase generated as temperature increasing. Depending on glucose content and thermal temperature, the average grain size of Fe{sub 3}O{sub 4} nanoparticles varied from 19.9 nm to 48 nm and saturation magnetization changed from 21.2 emu/g to 71.77 emu/g, which indicated that the saturation magnetization of Fe{sub 3}O{sub 4} nanoparticles fell off as the average grain size decreasing. These results were crucial not only from the application stand-point, but more importantly leaded to a new platform for further studies of high quality magnetic Fe{sub 3}O{sub 4} particles at nanoscale. - Highlights: • Solution combustion. • Carbothermal. • Fe{sub 3}O{sub 4} nanoparticles. • Magnetic properties.

Exploration of polyelectrolytes as draw solutes in forward osmosis processes

KAUST Repository

Ge, Qingchun

2012-03-01

The development of the forward osmosis (FO) process has been constrained by the slow development of appropriate draw solutions. Two significant concerns related to draw solutions are the draw solute leakage and intensiveenergy requirement in recycling draw solutes after the FO process. FO would be much attractive if there is no draw solute leakage and the recycle of draw solutes is easy and economic. In this study, polyelectrolytes of a series of polyacrylic acid sodium salts (PAA-Na), were explored as draw solutes in the FO process. The characteristics of high solubility in water and flexibility in structural configuration ensure the suitability of PAA-Na as draw solutes and their relative ease in recycle through pressure-driven membrane processes. The high water flux with insignificant salt leakage in the FO process and the high salt rejection in recycle processes reveal the superiority of PAA-Na to conventional ionic salts, such as NaCl, when comparing their FO performance via the same membranes. The repeatable performance of PAA-Na after recycle indicates the absence of any aggregation problems. The overall performance demonstrates that polyelectrolytes of PAA-Na series are promising as draw solutes, and the new concept of using polyelectrolytes as draw solutes in FO processes is applicable. © 2011 Elsevier Ltd.

Method of processing plutonium and uranium solution

International Nuclear Information System (INIS)

Otsuka, Katsuyuki; Kondo, Isao; Suzuki, Toru.

1989-01-01

Solutions of plutonium nitrate solutions and uranyl nitrate recovered in the solvent extraction step in reprocessing plants and nuclear fuel production plants are applied with low temperature treatment by means of freeze-drying under vacuum into residues containing nitrates, which are denitrated under heating and calcined under reduction into powders. That is, since complicate processes of heating, concentration and dinitration conducted so far for the plutonium solution and uranyl solution are replaced with one step of freeze-drying under vacuum, the process can be simplified significantly. In addition, since the treatment is applied at low temperature, occurrence of corrosion for the material of evaporation, etc. can be prevented. Further, the number of operators can be saved by dividing the operations into recovery of solidification products, supply and sintering of the solutions and vacuum sublimation. Further, since nitrates processed at a low temperature are powderized by heating dinitration, the powderization step can be simplified. The specific surface area and the grain size distribution of the powder is made appropriate and it is possible to obtain oxide powders of physical property easily to be prepared into pellets. (N.H.)

A generalized volumetric dispersion model for a class of two-phase separation/reaction: finite difference solutions

Science.gov (United States)

Siripatana, Chairat; Thongpan, Hathaikarn; Promraksa, Arwut

2017-03-01

This article explores a volumetric approach in formulating differential equations for a class of engineering flow problems involving component transfer within or between two phases. In contrast to conventional formulation which is based on linear velocities, this work proposed a slightly different approach based on volumetric flow-rate which is essentially constant in many industrial processes. In effect, many multi-dimensional flow problems found industrially can be simplified into multi-component or multi-phase but one-dimensional flow problems. The formulation is largely generic, covering counter-current, concurrent or batch, fixed and fluidized bed arrangement. It was also intended to use for start-up, shut-down, control and steady state simulation. Since many realistic and industrial operation are dynamic with variable velocity and porosity in relation to position, analytical solutions are rare and limited to only very simple cases. Thus we also provide a numerical solution using Crank-Nicolson finite difference scheme. This solution is inherently stable as tested against a few cases published in the literature. However, it is anticipated that, for unconfined flow or non-constant flow-rate, traditional formulation should be applied.

Tuning coercive force by adjusting electric potential in solution processed Co/Pt(111) and the mechanism involved

Science.gov (United States)

Chang, Cheng-Hsun-Tony; Kuo, Wei-Hsu; Chang, Yu-Chieh; Tsay, Jyh-Shen; Yau, Shueh-Lin

2017-03-01

A combination of a solution process and the control of the electric potential for magnetism represents a new approach to operating spintronic devices with a highly controlled efficiency and lower power consumption with reduced production cost. As a paradigmatic example, we investigated Co/Pt(111) in the Bloch-wall regime. The depression in coercive force was detected by applying a negative electric potential in an electrolytic solution. The reversible control of coercive force by varying the electric potential within few hundred millivolts is demonstrated. By changing the electric potential in ferromagnetic layers with smaller thicknesses, the efficiency for controlling the tunable coercive force becomes higher. Assuming that the pinning domains are independent of the applied electric potential, an electric potential tuning-magnetic anisotropy energy model was derived and provided insights into our knowledge of the relation between the electric potential tuning coercive force and the thickness of the ferromagnetic layer. Based on the fact that the coercive force can be tuned by changing the electric potential using a solution process, we developed a novel concept of electric-potential-tuned magnetic recording, resulting in a stable recording media with a high degree of writing ability.

Temperature dependence of the mechanical properties of equiatomic solid solution alloys with face-centered cubic crystal structures

International Nuclear Information System (INIS)

Wu, Z.; Bei, H.; Pharr, G.M.; George, E.P.

2014-01-01

Compared to decades-old theories of strengthening in dilute solid solutions, the mechanical behavior of concentrated solid solutions is relatively poorly understood. A special subset of these materials includes alloys in which the constituent elements are present in equal atomic proportions, including the high-entropy alloys of recent interest. A unique characteristic of equiatomic alloys is the absence of “solvent” and “solute” atoms, resulting in a breakdown of the textbook picture of dislocations moving through a solvent lattice and encountering discrete solute obstacles. To clarify the mechanical behavior of this interesting new class of materials, we investigate here a family of equiatomic binary, ternary and quaternary alloys based on the elements Fe, Ni, Co, Cr and Mn that were previously shown to be single-phase face-centered cubic (fcc) solid solutions. The alloys were arc-melted, drop-cast, homogenized, cold-rolled and recrystallized to produce equiaxed microstructures with comparable grain sizes. Tensile tests were performed at an engineering strain rate of 10 −3 s −1 at temperatures in the range 77–673 K. Unalloyed fcc Ni was processed similarly and tested for comparison. The flow stresses depend to varying degrees on temperature, with some (e.g. NiCoCr, NiCoCrMn and FeNiCoCr) exhibiting yield and ultimate strengths that increase strongly with decreasing temperature, while others (e.g. NiCo and Ni) exhibit very weak temperature dependencies. To better understand this behavior, the temperature dependencies of the yield strength and strain hardening were analyzed separately. Lattice friction appears to be the predominant component of the temperature-dependent yield stress, possibly because the Peierls barrier height decreases with increasing temperature due to a thermally induced increase of dislocation width. In the early stages of plastic flow (5–13% strain, depending on material), the temperature dependence of strain hardening is due

Tetragonal-cubic phase boundary in nanocrystalline ZrO2-Y2O3 solid solutions synthesized by gel-combustion

International Nuclear Information System (INIS)

Fabregas, Ismael O.; Craievich, Aldo F.; Fantini, Marcia C.A.; Millen, Ricardo P.; Temperini, Marcia L.A.; Lamas, Diego G.

2011-01-01

Research highlights: → Gel-combustion synthesis yields compositionally homogeneous, single-phased ZrO 2 -Y 2 O 3 nanopowders, that exhibit the presence at room temperature of three different phases depending on Y 2 O 3 content, namely two tetragonal forms (t' and t'') and the cubic phase. → Phase identification can be achieved by synchrotron XPD (SXPD) and Raman spectroscopy since the tetragonal forms and the cubic phase can be distinguished by these techniques. → The crystallographic features of ZrO 2 -Y 2 O 3 nanopowders were determined by SXPD. They are similar to those reported by Yashima and coworkers for compositionally homogeneous materials containing larger (micro)crystals. However, the lattice parameters are slightly different and the axial ratios c/a of our t' samples are smaller than those reported by these authors. → Compositional t'/t'' and t''/cubic phase boundaries are located at (9 ± 1) and (10.5 ± 0.5) mol% Y 2 O 3 , respectively. → For the whole series of nanocrystalline ZrO 2 -Y 2 O 3 solid solutions studied in the present work, no evidences of the presence of a mixture of phases - as reported by Yashima and coworkers for microcrystalline solid solutions - were detected. - Abstract: By means of synchrotron X-ray powder diffraction (SXPD) and Raman spectroscopy, we have detected, in a series of nanocrystalline and compositionally homogeneous ZrO 2 -Y 2 O 3 solid solutions, the presence at room temperature of three different phases depending on Y 2 O 3 content, namely two tetragonal forms and the cubic phase. The studied materials, with average crystallite sizes within the range 7-10 nm, were synthesized by a nitrate-citrate gel-combustion process. The crystal structure of these phases was also investigated by SXPD. The results presented here indicate that the studied nanocrystalline ZrO 2 -Y 2 O 3 solid solutions exhibit the same phases reported in the literature for compositionally homogeneous materials containing larger (micro

Influence of pressure on the solid state phase transformation of Cu–Al–Bi alloy

International Nuclear Information System (INIS)

Gong, Li; Jian-Hua, Liu; Wen-Kui, Wang; Ri-Ping, Liu

2010-01-01

The solid state phase transformation of Cu-Al-Bi alloy under high pressure was investigated by x-ray diffraction, energy dispersive spectroscopy and transmission electron microscopy. Experimental results show that the initial crystalline phase in the Cu-Al-Bi alloy annealed at 750 °C under the pressures in the range of 0–6 GPa is α-Cu solid solution (named as α-Cu phase below), and high pressure has a great influence on the crystallisation process of the Cu-Al-Bi alloy. The grain size of the α-Cu phase decreases with increasing pressure as the pressure is below about 3 GPa, and then increases (P > 3 GPa). The mechanism for the effects of high pressure on the crystallisation process of the alloy has been discussed. (condensed matter: structure, thermal and mechanical properties)

Solute coupled diffusion in osmotically driven membrane processes.

Science.gov (United States)

Hancock, Nathan T; Cath, Tzahi Y

2009-09-01

Forward osmosis (FO) is an emerging water treatment technology with potential applications in desalination and wastewater reclamation. In FO, water is extracted from a feed solution using the high osmotic pressure of a hypertonic solution that flows on the opposite side of a semipermeable membrane; however, solutes diffuse simultaneously through the membrane in both directions and may jeopardize the process. In this study, we have comprehensively explored the effects of different operating conditions on the forward diffusion of solutes commonly found in brackish water and seawater, and reverse diffusion of common draw solution solutes. Results show that reverse transport of solutes through commercially available FO membranes range between 80 mg to nearly 3,000 mg per liter of water produced. Divalent feed solutes have low permeation rates (less than 1 mmol/m2-hr) while monovalent ions and uncharged solutes exhibit higher permeation. Findings have significant implications on the performance and sustainability of the FO process.

Study of formation mechanism of incipient melting in thixo-cast Al–Si–Cu–Mg alloys

Energy Technology Data Exchange (ETDEWEB)

Du, Kang, E-mail: du126kang@126.com; Zhu, Qiang, E-mail: zhu.qiang@grinm.com; Li, Daquan, E-mail: lidaquan@grinm.com; Zhang, Fan, E-mail: sk_zf@163.com

2015-08-15

Mechanical properties of thixo-cast Al–Si–Cu–Mg alloys can be enhanced by T61 heat treatment. Copper and magnesium atoms in aluminum matrix can form homogeneously distributed precipitations after solution and aging treatment which harden the alloys. However, microsegregation of these alloying elements could form numerous tiny multi-compound phases during solidification. These phases could cause incipient melting defects in subsequent heat treatment process and degrade the macro-mechanical properties of productions. This study is to present heterogeneous distribution of Cu, Si, and Mg elements and formation of incipient melting defects (pores). In this study, incipient melting pores that occurred during solution treatment at various temperatures, even lower than common melting points of various intermetallic phases, were identified, in terms of a method of investigating the same surface area in the samples before and after solution treatment in a vacuum environment. The results also show that the incipient melting mostly originates at the clusters with fine intermetallic particles while also some at the edge of block-like Al{sub 2}Cu. The fine particles were determined being Al{sub 2}Cu, Al{sub 5}Cu{sub 2}Mg{sub 8}Si{sub 6} and Al{sub 8}Mg{sub 3}FeSi{sub 2}. Tendency of the incipient melting decreases with decreases of the width of the clusters. The formation mechanism of incipient melting pores in solution treatment process was discussed using both the Fick law and the LSW theory. Finally, a criterion of solution treatment to avoid incipient melting pores for the thixo-cast alloys is proposed. - Highlights: • In-situ comparison technique was used to analysis the change of eutectic phases. • The ralationship between eutectic phase size and incipient melting was studied. • Teat treatment criterion for higher incipient melting resistance was proposed.

Study of formation mechanism of incipient melting in thixo-cast Al–Si–Cu–Mg alloys

International Nuclear Information System (INIS)

Du, Kang; Zhu, Qiang; Li, Daquan; Zhang, Fan

2015-01-01

Mechanical properties of thixo-cast Al–Si–Cu–Mg alloys can be enhanced by T61 heat treatment. Copper and magnesium atoms in aluminum matrix can form homogeneously distributed precipitations after solution and aging treatment which harden the alloys. However, microsegregation of these alloying elements could form numerous tiny multi-compound phases during solidification. These phases could cause incipient melting defects in subsequent heat treatment process and degrade the macro-mechanical properties of productions. This study is to present heterogeneous distribution of Cu, Si, and Mg elements and formation of incipient melting defects (pores). In this study, incipient melting pores that occurred during solution treatment at various temperatures, even lower than common melting points of various intermetallic phases, were identified, in terms of a method of investigating the same surface area in the samples before and after solution treatment in a vacuum environment. The results also show that the incipient melting mostly originates at the clusters with fine intermetallic particles while also some at the edge of block-like Al 2 Cu. The fine particles were determined being Al 2 Cu, Al 5 Cu 2 Mg 8 Si 6 and Al 8 Mg 3 FeSi 2 . Tendency of the incipient melting decreases with decreases of the width of the clusters. The formation mechanism of incipient melting pores in solution treatment process was discussed using both the Fick law and the LSW theory. Finally, a criterion of solution treatment to avoid incipient melting pores for the thixo-cast alloys is proposed. - Highlights: • In-situ comparison technique was used to analysis the change of eutectic phases. • The ralationship between eutectic phase size and incipient melting was studied. • Teat treatment criterion for higher incipient melting resistance was proposed

In situ microscopy of the self-assembly of branched nanocrystals in solution

Science.gov (United States)

Sutter, Eli; Sutter, Peter; Tkachenko, Alexei V.; Krahne, Roman; de Graaf, Joost; Arciniegas, Milena; Manna, Liberato

2016-04-01

Solution-phase self-assembly of nanocrystals into mesoscale structures is a promising strategy for constructing functional materials from nanoscale components. Liquid environments are key to self-assembly since they allow suspended nanocrystals to diffuse and interact freely, but they also complicate experiments. Real-time observations with single-particle resolution could have transformative impact on our understanding of nanocrystal self-assembly. Here we use real-time in situ imaging by liquid-cell electron microscopy to elucidate the nucleation and growth mechanism and properties of linear chains of octapod-shaped nanocrystals in their native solution environment. Statistical mechanics modelling based on these observations and using the measured chain-length distribution clarifies the relative importance of dipolar and entropic forces in the assembly process and gives direct access to the interparticle interaction. Our results suggest that monomer-resolved in situ imaging combined with modelling can provide unprecedented quantitative insight into the microscopic processes and interactions that govern nanocrystal self-assembly in solution.

On the effect of incremental forming on alpha phase precipitation and mechanical behavior of beta-Ti-10V-2Fe-3Al

Science.gov (United States)

Winter, S.; F-X Wagner, M.

2016-03-01

A combination of good ductility and fatigue resistance makes β-titanium alloys interesting for many current and potential future applications. The mechanical behavior is primarily determined by microstructural parameters like (beta phase) grain size, morphology and volume fraction of primary / secondary α-phase precipitates, and this allows changing and optimizing their mechanical properties across a wide range. In this study, we investigate the possibility to modify the microstructure of the high-strength beta titanium alloy Ti-10V-2Fe-3Al, with a special focus on shape and volume fraction of primary α-phase. In addition to the conventional strategy for precipitation of primary α, a special thermo-mechanical processing is performed; this processing route combines the conventional heat treatment with incremental forming during the primary α-phase annealing. After incremental forming, considerable variations in terms of microstructure and mechanical properties can be obtained for different thermo-mechanical processing routes. The microstructures of the deformed samples are characterized by globular as well as lamellar (bimodal) α precipitates, whereas conventional annealing only results in the formation of lamellar precipitates. Because of the smaller size, and the lower amount, of α-phase after incremental forming, tensile strength is not as high as after the conventional strategy. However, high amounts of grain boundary α and lamellar αp-phase in the undeformed samples lead to a significantly lower ductility in comparison to the matrix with bimodal structures obtained by thermo-mechanical processing. These results illustrate the potential of incremental forming during the annealing to modify the microstructure of the beta titanium Ti-10V-2Fe-3Al in a wide range of volume fractions and morphologies of the primary α phase, which in turn leads to considerably changes, and improved, mechanical properties.

A direct comparison of protein structure in the gas and solution phase: the Trp-cage

DEFF Research Database (Denmark)

Patriksson, Alexandra; Adams, Christopher M; Kjeldsen, Frank

2007-01-01

Molecular dynamics simulations of zwitterions of the Trp-cage protein in the gas phase show that the most stable ion in vacuo has preserved the charge locations acquired in solution. A direct comparison of the gas and solution-phase structures reveals that, despite the similarity in charge location...

Removal mechanism of phosphate from aqueous solution by fly ash.

Science.gov (United States)

Lu, S G; Bai, S Q; Zhu, L; Shan, H D

2009-01-15

This work studied the effectiveness of fly ash in removing phosphate from aqueous solution and its related removal mechanism. The adsorption and precipitation of phosphate by fly ash were investigated separately in order to evaluate their role in the removal of phosphate. Results showed that the removal of phosphate by fly ash was rapid. The removal percentage of phosphate in the first 5min reached 68-96% of the maximum removal of phosphate by fly ash. The removal processes of phosphate by fly ash included a fast and large removal representing precipitation, then a slower and longer removal due to adsorption. The adsorption of phosphate on fly ash could be described well by Freundlich isotherm equation. The pH and Ca2+ concentration of fly ash suspension were decreased with the addition of phosphate, which suggests that calcium phosphate precipitation is a major mechanism of the phosphate removal. Comparison of the relative contribution of the adsorption and precipitation to the total removal of phosphate by fly ash showed that the adsorption accounted for 30-34% of the total removal of phosphate, depending on the content of CaO in fly ash. XRD patterns of the fly ash before and after phosphate adsorption revealed that phosphate salt (CaHPO4 x 2H2O) was formed in the adsorption process. Therefore, the removal of phosphate by fly ash can be attributed to the formation of phosphate precipitation as a brushite and the adsorption on hydroxylated oxides. The results suggested that the use of fly ash could be a promising solution to the removal of phosphate in the wastewater treatment and pollution control.

Effect of solution heat treatment on the precipitation behavior and strengthening mechanisms of electron beam smelted Inconel 718 superalloy

Energy Technology Data Exchange (ETDEWEB)

You, Xiaogang [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116023 (China); Laboratory for New Energy Material Energetic Beam Metallurgical Equipment Engineering of Liaoning Province, Dalian 116024 (China); Tan, Yi, E-mail: tanyi@dlut.edu.cn [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116023 (China); Laboratory for New Energy Material Energetic Beam Metallurgical Equipment Engineering of Liaoning Province, Dalian 116024 (China); Shi, Shuang [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116023 (China); Laboratory for New Energy Material Energetic Beam Metallurgical Equipment Engineering of Liaoning Province, Dalian 116024 (China); Yang, Jenn-Ming [Department of Materials Science and Engineering, University of California, Los Angeles, CA 90095 (United States); Wang, Yinong [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116023 (China); Li, Jiayan; You, Qifan [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116023 (China); Laboratory for New Energy Material Energetic Beam Metallurgical Equipment Engineering of Liaoning Province, Dalian 116024 (China)

2017-03-24

Inconel 718 superalloy was fabricated by electron beam smelting (EBS) technique. The effect of solution heat treatment on the precipitation behavior and mechanical properties of EBS 718 superalloys were studied, the strengthening mechanisms were analyzed and related to the mechanical properties. The results indicate that the optimized microstructures can be acquired by means of EBS, which is attributed to the rapid cooling rate of approximately 280 ℃/min. The solution heat treatment shows a great impact on the microstructures, precipitation behavior and mechanical properties of EBS 718 superalloy. The γ'' phase shows an apt to precipitate at relatively lower solution temperatures followed by aging, while the γ' precipitates are prone to precipitate at higher temperatures. When solution treated at 1150 ℃, the γ' precipitates are dispersively distributed in the matrix with size and volume fraction of 8.43 nm and 21.66%, respectively, a Vickers hardness of approximately 489 HV{sub 0.1} is observed for the aged superalloy. The precipitation strengthening effect of EBS 718 superalloy could be elucidated by considering the interaction between the dislocations and γ''/γ' precipitates. The shearing of γ' is resisted by the coherency strengthening and formation of antiphase boundary (APB), which shows equal effect as weakly coupled dislocation (WCD) model. And for γ'', the strengthening effect is much more prominent with the primary strengthening mechanism of ordering. Moreover, it is interestingly found that the strengthening mechanism of stacking fault (SF) shearing coexists with APB shearing, and SF shearing plays a major role in strengthening of EBS 718 superalloy.

Solution mechanism guide: implementing innovation within a research & development organization.

Science.gov (United States)

Keeton, Kathryn E; Richard, Elizabeth E; Davis, Jeffrey R

2014-10-01

In order to create a culture more open to novel problem-solving mechanisms, NASA's Human Health and Performance Directorate (HH&P) created a strategic knowledge management tool that educates employees about innovative problem-solving techniques, the Solution Mechanism Guide (SMG). The SMG is a web-based, interactive guide that leverages existing and innovative problem-solving methods and presents this information as a unique user experience so that the employee is empowered to make the best decision about which problem-solving tool best meets their needs. By integrating new and innovative methods with existing problem solving tools, the SMG seamlessly introduces open innovation and collaboration concepts within HH&P to more effectively address human health and performance risks. This commentary reviews the path of creating a more open and innovative culture within HH&P and the process and development steps that were taken to develop the SMG.

Low-energy mechanically milled τ-phase MnAl alloys with high coercivity and magnetization

International Nuclear Information System (INIS)

Lu, Wei; Niu, Junchao; Wang, Taolei; Xia, Kada; Xiang, Zhen; Song, Yiming; Zhang, Hong; Yoshimura, Satoru; Saito, Hitoshi

2016-01-01

The high cost of rare earth elements makes the use of high-performance permanent magnets commercially very expensive. MnAl magnetic material is one of the most promising Rare-Earth-free permanent magnets due to its obvious characteristics. However, the coercivity of MnAl alloys produced by melt spinning followed by appropriate treatment is relatively low. In this investigation, a high coercivity up to 5.3 kOe and saturation magnetization of ∼62 emu/g (with an applied magnetic field of 19.5 kOe) were obtained in the mechanically milled τ-phase Mn_5_7Al_4_3 alloy. As milling time goes on, the coercivity firstly increases and then decreases, leading to the formation of knee-point coercivity, while the saturation magnetization decreases simultaneously. The structural imperfections such as disordering and defects play the most important role in the changes of magnetic properties of τ-phase MnAl alloys processed by low-energy mechanical milling. The present results will be helpful for the development of processing protocols for the optimization of τ-phase MnAl alloys as high performance Rare-Earth-free permanent magnets. - Highlights: • Successful fabrication of pure τ-phase Mn_5_7Al_4_3 alloy by melt spinning and low-energy ball milling processes. • High coercivity (~5.3 kOe) and magnetization (~62 emu/g) were obtained in τ-phase Mn_5_7Al_4_3 alloy. • Disordering and defects play the most important role in the changes of magnetic properties.

Low-energy mechanically milled τ-phase MnAl alloys with high coercivity and magnetization

Energy Technology Data Exchange (ETDEWEB)

Lu, Wei, E-mail: weilu@tongji.edu.cn [School of Materials Science and Engineering, Shanghai Key Lab. of D& A for Metal-Functional Materials, Tongji University, Shanghai 200092 (China); Research Center for Engineering Science, Akita University, Akita 010-8502 Japan (Japan); Niu, Junchao; Wang, Taolei; Xia, Kada; Xiang, Zhen; Song, Yiming [School of Materials Science and Engineering, Shanghai Key Lab. of D& A for Metal-Functional Materials, Tongji University, Shanghai 200092 (China); Zhang, Hong; Yoshimura, Satoru; Saito, Hitoshi [Research Center for Engineering Science, Akita University, Akita 010-8502 Japan (Japan)

2016-08-05

The high cost of rare earth elements makes the use of high-performance permanent magnets commercially very expensive. MnAl magnetic material is one of the most promising Rare-Earth-free permanent magnets due to its obvious characteristics. However, the coercivity of MnAl alloys produced by melt spinning followed by appropriate treatment is relatively low. In this investigation, a high coercivity up to 5.3 kOe and saturation magnetization of ∼62 emu/g (with an applied magnetic field of 19.5 kOe) were obtained in the mechanically milled τ-phase Mn{sub 57}Al{sub 43} alloy. As milling time goes on, the coercivity firstly increases and then decreases, leading to the formation of knee-point coercivity, while the saturation magnetization decreases simultaneously. The structural imperfections such as disordering and defects play the most important role in the changes of magnetic properties of τ-phase MnAl alloys processed by low-energy mechanical milling. The present results will be helpful for the development of processing protocols for the optimization of τ-phase MnAl alloys as high performance Rare-Earth-free permanent magnets. - Highlights: • Successful fabrication of pure τ-phase Mn{sub 57}Al{sub 43} alloy by melt spinning and low-energy ball milling processes. • High coercivity (~5.3 kOe) and magnetization (~62 emu/g) were obtained in τ-phase Mn{sub 57}Al{sub 43} alloy. • Disordering and defects play the most important role in the changes of magnetic properties.

Numerical simulation of solute trapping phenomena using phase-field solidification model for dilute binary alloys

Directory of Open Access Journals (Sweden)

Henrique Silva Furtado

2009-09-01

Full Text Available Numerical simulation of solute trapping during solidification, using two phase-field model for dilute binary alloys developed by Kim et al. [Phys. Rev. E, 60, 7186 (1999] and Ramirez et al. [Phys. Rev. E, 69, 05167 (2004] is presented here. The simulations on dilute Cu-Ni alloy are in good agreement with one dimensional analytic solution of sharp interface model. Simulation conducted under small solidification velocity using solid-liquid interface thickness (2λ of 8 nanometers reproduced the solute (Cu equilibrium partition coefficient. The spurious numerical solute trapping in solid phase, due to the interface thickness was negligible. A parameter used in analytical solute trapping model was determined by isothermal phase-field simulation of Ni-Cu alloy. Its application to Si-As and Si-Bi alloys reproduced results that agree reasonably well with experimental data. A comparison between the three models of solute trapping (Aziz, Sobolev and Galenko [Phys. Rev. E, 76, 031606 (2007] was performed. It resulted in large differences in predicting the solidification velocity for partition-less solidification, indicating the necessity for new and more acute experimental data.

A Brokering Solution for Business Process Execution

Science.gov (United States)

Santoro, M.; Bigagli, L.; Roncella, R.; Mazzetti, P.; Nativi, S.

2012-12-01

Predicting the climate change impact on biodiversity and ecosystems, advancing our knowledge of environmental phenomena interconnection, assessing the validity of simulations and other key challenges of Earth Sciences require intensive use of environmental modeling. The complexity of Earth system requires the use of more than one model (often from different disciplines) to represent complex processes. The identification of appropriate mechanisms for reuse, chaining and composition of environmental models is considered a key enabler for an effective uptake of a global Earth Observation infrastructure, currently pursued by the international geospatial research community. The Group on Earth Observation (GEO) Model Web initiative aims to increase present accessibility and interoperability of environmental models, allowing their flexible composition into complex Business Processes (BPs). A few, basic principles are at the base of the Model Web concept (Nativi, et al.): 1. Open access 2. Minimal entry-barriers 3. Service-driven approach 4. Scalability In this work we propose an architectural solution aiming to contribute to the Model Web vision. This solution applies the Brokering approach for facilitiating complex multidisciplinary interoperability. The Brokering approach is currently adopted in the new GEOSS Common Infrastructure (GCI) as was presented at the last GEO Plenary meeting in Istanbul, November 2011. According to the Brokering principles, the designed system is flexible enough to support the use of multiple BP design (visual) tools, heterogeneous Web interfaces for model execution (e.g. OGC WPS, WSDL, etc.), and different Workflow engines. We designed and prototyped a component called BP Broker that is able to: (i) read an abstract BP, (ii) "compile" the abstract BP into an executable one (eBP) - in this phase the BP Broker might also provide recommendations for incomplete BPs and parameter mismatch resolution - and (iii) finally execute the eBP using a

All-Solution-Processed Metal-Oxide-Free Flexible Organic Solar Cells with Over 10% Efficiency.

Science.gov (United States)

Song, Wei; Fan, Xi; Xu, Bingang; Yan, Feng; Cui, Huiqin; Wei, Qiang; Peng, Ruixiang; Hong, Ling; Huang, Jiaming; Ge, Ziyi

2018-05-16

All-solution-processing at low temperatures is important and desirable for making printed photovoltaic devices and also offers the possibility of a safe and cost-effective fabrication environment for the devices. Herein, an all-solution-processed flexible organic solar cell (OSC) using poly(3,4-ethylenedioxythiophene):poly-(styrenesulfonate) electrodes is reported. The all-solution-processed flexible devices yield the highest power conversion efficiency of 10.12% with high fill factor of over 70%, which is the highest value for metal-oxide-free flexible OSCs reported so far. The enhanced performance is attributed to the newly developed gentle acid treatment at room temperature that enables a high-performance PEDOT:PSS/plastic underlying substrate with a matched work function (≈4.91 eV), and the interface engineering that endows the devices with better interface contacts and improved hole mobility. Furthermore, the flexible devices exhibit an excellent mechanical flexibility, as indicated by a high retention (≈94%) of the initial efficiency after 1000 bending cycles. This work provides a simple route to fabricate high-performance all-solution-processed flexible OSCs, which is important for the development of printing, blading, and roll-to-roll technologies. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Performance Evaluation of Absorbent Solution for Draw Solute Recovery in Forward Osmosis Desalination Process

International Nuclear Information System (INIS)

Kim, Young; Lee, Jong Hoon; Lee, Kong Hoon; Kim, Yu-Chang; Oh, Dong Wook; Lee, Jungho

2013-01-01

Although forward osmosis desalination technology has drawn substantial attention as a next-generation desalination method, the energy efficiency of its draw solution treatment process should be improved for its commercialization. When ammonium bicarbonate is used as the draw solute, the system consists of forward-osmosis membrane modules, draw solution separation and recovery processes. Mixed gases of ammonia and carbon dioxide generated during the draws solution separation, need to be recovered to re-concentrate ammonium bicarbonate solution, for continuous operation as well as for the economic feasibility. The diluted ammonium bicarbonate solution has been proposed as the absorbent for the draw solution regeneration. In this study, experiments are conducted to investigate performance and features of the absorption corresponding to absorbent concentration. It is concluded that ammonium bicarbonate solution can be used to recover the generated ammonia and carbon dioxide. The results will be applied to design and operation of pilot-scale forward-osmosis desalination system

Performance Evaluation of Absorbent Solution for Draw Solute Recovery in Forward Osmosis Desalination Process

Energy Technology Data Exchange (ETDEWEB)

Kim, Young; Lee, Jong Hoon; Lee, Kong Hoon; Kim, Yu-Chang; Oh, Dong Wook; Lee, Jungho [Korea Institute of Machinery Materials, Daejeon (Korea, Republic of)

2013-04-15

Although forward osmosis desalination technology has drawn substantial attention as a next-generation desalination method, the energy efficiency of its draw solution treatment process should be improved for its commercialization. When ammonium bicarbonate is used as the draw solute, the system consists of forward-osmosis membrane modules, draw solution separation and recovery processes. Mixed gases of ammonia and carbon dioxide generated during the draws solution separation, need to be recovered to re-concentrate ammonium bicarbonate solution, for continuous operation as well as for the economic feasibility. The diluted ammonium bicarbonate solution has been proposed as the absorbent for the draw solution regeneration. In this study, experiments are conducted to investigate performance and features of the absorption corresponding to absorbent concentration. It is concluded that ammonium bicarbonate solution can be used to recover the generated ammonia and carbon dioxide. The results will be applied to design and operation of pilot-scale forward-osmosis desalination system.

Physical and Mathematical Questions on Signal Processing in Multibase Phase Direction Finders

Science.gov (United States)

Denisov, V. P.; Dubinin, D. V.; Meshcheryakov, A. A.

2018-02-01

Questions on improving the accuracy of multiple-base phase direction finders by rejecting anomalously large errors in the process of resolving the measurement ambiguities are considered. A physical basis is derived and calculated relationships characterizing the efficiency of the proposed solutions are obtained. Results of a computer simulation of a three-base direction finder are analyzed, along with field measurements of a three-base direction finder along near-ground paths.

Aqueous Two-Phase Extraction of Polyphenols Using a Microchannel System – Process Optimization and Intensification

Directory of Open Access Journals (Sweden)

Ivana Rukavina

2011-01-01

Full Text Available Polyphenols are one of the most numerous and widespread groups of compounds in the plant world. Nowadays, organic solvents such as methanol, ethanol, acetone, dimethylformamide, ethyl acetate and diethylether are mainly used for the extraction of polyphenols. These solvents require special process conditions and special care in the disposal of the used solvents. In this paper, the extraction of polyphenols from the model solution was performed using the aqueous two-phase system which contains 80.90 % water and represents low burden on the environment. The aqueous solution of gallic acid (GA was used as a model solution of polyphenols. The extraction was performed in the aqueous two-phase system containing PEG6000/H2O/(NH42SO4 in a macroextractor (V=10 mL and microextractor (V=14 ƒμL. The influence of the process parameters, the concentration of gallic acid, pH and composition of the aqueous two-phase system was investigated in order to maximize the partition coefficient. The method of multifactor experimental planning was used to optimize the extraction process and the results were statistically analysed using the evolutionary operation method (EVOP. Optimal operating conditions of the extraction process were pH=6.50, γGA=4.50 g/L, the mass fraction of polyethylene glycol (PEG wPEG=0.1037 g/g and the mass fraction of ammonium sulphate (AMS wAMS=0.0925 g/g. Under these conditions the maximal partition coefficient of K=5.54 and the extraction efficiency of E=89.11 % were achieved and successfully applied for total phenol extraction from white wine in the macro- and microextractor. Approximately the same partition coefficients and extraction efficiency were achieved in the microextractor within a 60-fold shorter residence time.

On phase-space representations of quantum mechanics using

Indian Academy of Sciences (India)

space representations of quantum mechanics using Glauber coherent states. DIÓGENES CAMPOS. Research Article Volume 87 Issue 2 August ... Keywords. Phase-space quantum mechanics, coherent states, Husimi function, Wigner function ...

Intermolecular interactions in the condensed phase

DEFF Research Database (Denmark)

Christensen, Anders S.; Kromann, Jimmy Charnley; Jensen, Jan Halborg

2017-01-01

To facilitate further development of approximate quantum mechanical methods for condensed phase applications, we present a new benchmark dataset of intermolecular interaction energies in the solution phase for a set of 15 dimers, each containing one charged monomer. The reference interaction energy...... and solution phases. As most approximate QM methods are parametrized and evaluated using data measured or calculated in the gas phase, the dataset represents an important first step toward calibrating QM based methods for application in the condensed phase where polarization and exchange repulsion need...

Effects of neutron irradiation on mechanical properties of silicon carbide composites fabricated by nano-infiltration and transient eutectic-phase process

International Nuclear Information System (INIS)

Koyanagi, T.; Hinoki, T.; Shimoda, K.; Ozawa, K.; Katoh, Y.

2014-01-01

Unidirectional silicon carbide (SiC)-fiber-reinforced SiC matrix (SiC/SiC) composites fabricated by a nano-infiltration and transient eutectic-phase (NITE) process were irradiated with neutrons at 830°C to 5.9 dpa, and at 1270°C to 5.8 dpa. The in-plane and trans-thickness tensile and the inter-laminar shear properties were evaluated at ambient temperature. The mechanical characteristics, including the quasi-ductile behavior, the proportional limit stress, and the ultimate tensile strength, were retained subsequent to irradiation. Analysis of the stress–strain hysteresis loop indicated the increased fiber/matrix interface friction and the decreased residual stresses. The inter-laminar shear strength exhibited a significant decrease following irradiation. (author)

Unifying hydrotropy under Gibbs phase rule.

Science.gov (United States)

Shimizu, Seishi; Matubayasi, Nobuyuki

2017-09-13

The task of elucidating the mechanism of solubility enhancement using hydrotropes has been hampered by the wide variety of phase behaviour that hydrotropes can exhibit, encompassing near-ideal aqueous solution, self-association, micelle formation, and micro-emulsions. Instead of taking a field guide or encyclopedic approach to classify hydrotropes into different molecular classes, we take a rational approach aiming at constructing a unified theory of hydrotropy based upon the first principles of statistical thermodynamics. Achieving this aim can be facilitated by the two key concepts: (1) the Gibbs phase rule as the basis of classifying the hydrotropes in terms of the degrees of freedom and the number of variables to modulate the solvation free energy; (2) the Kirkwood-Buff integrals to quantify the interactions between the species and their relative contributions to the process of solubilization. We demonstrate that the application of the two key concepts can in principle be used to distinguish the different molecular scenarios at work under apparently similar solubility curves observed from experiments. In addition, a generalization of our previous approach to solutes beyond dilution reveals the unified mechanism of hydrotropy, driven by a strong solute-hydrotrope interaction which overcomes the apparent per-hydrotrope inefficiency due to hydrotrope self-clustering.

Elastic and Mechanical Properties of the MAX Phases

Science.gov (United States)

Barsoum, Michel W.; Radovic, Miladin

2011-08-01

The more than 60 ternary carbides and nitrides, with the general formula Mn+1AXn—where n = 1, 2, or 3; M is an early transition metal; A is an A-group element (a subset of groups 13-16); and X is C and/or N—represent a new class of layered solids, where Mn+1Xn layers are interleaved with pure A-group element layers. The growing interest in the Mn+1AXn phases lies in their unusual, and sometimes unique, set of properties that can be traced back to their layered nature and the fact that basal dislocations multiply and are mobile at room temperature. Because of their chemical and structural similarities, the MAX phases and their corresponding MX phases share many physical and chemical properties. In this paper we review our current understanding of the elastic and mechanical properties of bulk MAX phases where they differ significantly from their MX counterparts. Elastically the MAX phases are in general quite stiff and elastically isotropic. The MAX phases are relatively soft (2-8 GPa), are most readily machinable, and are damage tolerant. Some of them are also lightweight and resistant to thermal shock, oxidation, fatigue, and creep. In addition, they behave as nonlinear elastic solids, dissipating 25% of the mechanical energy during compressive cycling loading of up to 1 GPa at room temperature. At higher temperatures, they undergo a brittle-to-plastic transition, and their mechanical behavior is a strong function of deformation rate.

Devitrification kinetics and phase selection mechanisms in Cu-Zr metallic glasses

Energy Technology Data Exchange (ETDEWEB)

Kalay, Ilkay [Iowa State Univ., Ames, IA (United States)

2010-01-01

Metallic glasses have been a promising class of materials since their discovery in the 1960s. Indeed, remarkable chemical, mechanical and physical properties have attracted considerable attention, and several excellent reviews are available. Moreover, the special group of glass forming alloys known as the bulk metallic glasses (BMG) become amorphous solids even at relatively low cooling rates, allowing them to be cast in large cross sections, opening the scope of potential applications to include bulk forms and net shape structural applications. Recent studies have been reported for new bulk metallic glasses produced with lower cooling rates, from 0.1 to several hundred K/s. Some of the application products of BMGs include sporting goods, high performance springs and medical devices. Several rapid solidification techniques, including melt-spinning, atomization and surface melting have been developed to produce amorphous alloys. The aim of all these methods is to solidify the liquid phase rapidly enough to suppress the nucleation and growth of crystalline phases. Furthermore, the production of amorphous/crystalline composite (ACC) materials by partial crystallization of amorphous precursor has recently given rise to materials that provide better mechanical and magnetic properties than the monolithic amorphous or crystalline alloys. In addition, these advances illustrate the broad untapped potential of using the glassy state as an intermediate stage in the processing of new materials and nanostructures. These advances underlie the necessity of investigations on prediction and control of phase stability and microstructural dynamics during both solidification and devitrification processes. This research presented in this dissertation is mainly focused on Cu-Zr and Cu-Zr-Al alloy systems. The Cu-Zr binary system has high glass forming ability in a wide compositional range (35-70 at.% Cu). Thereby, Cu-Zr based alloys have attracted much attention according to fundamental

Development of a freeze-drying process of waste-solution, 2

International Nuclear Information System (INIS)

Kondo, Isao; Kawasaki, Takeshi

1988-01-01

The waste solution treatment process in Plutonium Conversion Development Facility (PCDF) consists of Evaporation-Condensation and Neutrazation-Agglometation-Precipitation process, which produces the distillate as recovered acid at first step and separates Pu-U element from condenced solution at second step. This process needs many stages to get high decontamination efficiency and then the Evaporator is in very corrosive state because the nitric acid solution is heated over 100 degrees C to be evaporated. So, in PCDF, it was started the development of Freeze-Drying process to waste solution treatment. This process is suitable for a little quantity of the solution including nitric acid as produced in the Microwave Heating method. Moreover the process has high decontamination efficiency and has good performance of equipment. The result of the cold test of Freeze-Drying process with nitric acid is discribed in this paper. (author)

Electrochemical processing of nitrate waste solutions

International Nuclear Information System (INIS)

Genders, D.; Weinberg, N.; Hartsough, D.

1992-01-01

The second phase of research performed at The Electrosynthesis Co., Inc. has demonstrated the successful removal of nitrite and nitrate from a synthetic effluent stream via a direct electrochemical reduction at a cathode. It was shown that direct reduction occurs at good current efficiencies in 1,000 hour studies. The membrane separation process is not readily achievable for the removal of nitrites and nitrates due to poor current efficiencies and membrane stability problems. A direct reduction process was studied at various cathode materials in a flow cell using the complete synthetic mix. Lead was found to be the cathode material of choice, displaying good current efficiencies and stability in short and long term tests under conditions of high temperature and high current density. Several anode materials were studied in both undivided and divided cell configurations. A divided cell configuration was preferable because it would prevent re-oxidation of nitrite by the anode. The technical objective of eliminating electrode fouling and solids formation was achieved although anode materials which had demonstrated good stability in short term divided cell tests corroded in 1,000 hour experiments. The cause for corrosion is thought to be F - ions from the synthetic mix migrating across the cation exchange membrane and forming HF in the acid anolyte. Other possibilities for anode materials were explored. A membrane separation process was investigated which employs an anion and cation exchange membrane to remove nitrite and nitrate, recovering caustic and nitric acid. Present research has shown poor current efficiencies for nitrite and nitrate transport across the anion exchange membrane due to co-migration of hydroxide anions. Precipitates form within the anion exchange membranes which would eventually result in the failure of the membranes. Electrochemical processing offers a highly promising and viable method for the treatment of nitrate waste solutions

Process for iron separation from an organic solution containing uranium

International Nuclear Information System (INIS)

Textoris, A.; Lyaudet, G.; Bathelier, A.

1987-01-01

Iron is separated from an organic solution of U and Fe in a phosphine oxide and an acid organic phosphorus compound by reaction on oxalic acid or a mixture of sulfuric and phosphoric acid or phosphoric acid. Uranium stays in the initial organic solution and iron is transferred to the aqueous phase [fr

Liquid phase sintered SiC. Processing and transformation controlled microstructure tailoring

Directory of Open Access Journals (Sweden)

V.A. Izhevskyi

2000-10-01

Full Text Available Microstructure development and phase formation processes during sintering of silicon carbide based materials with AlN-Y2O3, AlN-Yb2O3, and AlN-La2O3 sintering additives were investigated. Densification of the materials occurred by liquid-phase sintering mechanism. Proportion of alpha- and beta-SiC powders in the initial mixtures was a variable parameter, while the molar ratio of AlN/RE2O3, and the total amount of additives (10 vol. % were kept constant. Shrinkage behavior during sintering in interrelation with the starting composition of the material and the sintering atmosphere was investigated by high temperature dilatometry. Kinetics of b-SiC to a-SiC phase transformation during post-sintering heat treatment at temperatures 1900-1950 °C was studied, the degree of phase transformation being determined by quantitative x-ray analysis using internal standard technique. Evolution of microstructure resulting from beta-SiC to alpha-SiC transformation was followed up by scanning electron microscopy on polished and chemically etched samples. Transformation-controlled grain growth mechanism similar to the one observed for silicon nitride based ceramics was established. Possibility of in-situ platelet reinforced dense SiC-based ceramics fabrication with improved mechanical properties by means of sintering was shown.

The Process of Optimizing Mechanical Sound Quality in Product Design

DEFF Research Database (Denmark)

Eriksen, Kaare; Holst, Thomas

2011-01-01

The research field concerning optimizing product sound quality is a relatively unexplored area, and may become difficult for designers to operate in. To some degree, sound is a highly subjective parameter, which is normally targeted sound specialists. This paper describes the theoretical...... and practical background for managing a process of optimizing the mechanical sound quality in a product design by using simple tools and workshops systematically. The procedure is illustrated by a case study of a computer navigation tool (computer mouse or mouse). The process is divided into 4 phases, which...... clarify the importance of product sound, defining perceptive demands identified by users, and, finally, how to suggest mechanical principles for modification of an existing sound design. The optimized mechanical sound design is followed by tests on users of the product in its use context. The result...

The corrosion mechanism of the sintered (Ce, Nd)-Fe-B magnets prepared by double main phase and single main phase approaches

Science.gov (United States)

Shi, Xiaoning; Zhu, Minggang; Zhou, Dong; Song, Liwei; Guo, Zhaohui; Li, Jia; Li, Wei

2018-05-01

The sintered (Ce, Nd)-Fe-B magnets were produced widely by Double Main Phase (DMP) method in China as the magnetic properties of the DMP magnets are superior to those of single main phase (SMP) magnets with the same nominal composition. In this work, the microstructure and corrosion mechanism of the sintered (Ce0.2Nd0.8)30FebalB (wt.%) magnets prepared by DMP and SMP method were studied in detail. Compared to SMP magnets, the DMP magnets have more positive corrosion potential, lower corrosion current density, larger electron transfer resistance, and lower mass loss of the free corrosion experiment in 0.5mol/l Na2SO4 aqueous solution. All of the results show that the DMP magnets have better corrosion resistance than SMP magnets. The back scattered electron images show that the crystalline grains of the DMP magnets are sphericity with a smooth surface while the SMP ones have plenty of edges and corners. Besides, the distribution of Ce/Nd is much more uneven in both magnetic phase and rare earth (Re)-rich phase of the DMP magnets than those of SMP magnets. After corrosion, DMP magnets show eroded magnetic phase and intact Re-rich phase, which indicate that galvanic corrosion of the Re-rich phase acting as the cathode appears.

Low-Voltage Solution-Processed Hybrid Light-Emitting Transistors.

Science.gov (United States)

Chaudhry, Mujeeb Ullah; Tetzner, Kornelius; Lin, Yen-Hung; Nam, Sungho; Pearson, Christopher; Groves, Chris; Petty, Michael C; Anthopoulos, Thomas D; Bradley, Donal D C

2018-05-21

We report the development of low operating voltages in inorganic-organic hybrid light-emitting transistors (HLETs) based on a solution-processed ZrO x gate dielectric and a hybrid multilayer channel consisting of the heterojunction In 2 O 3 /ZnO and the organic polymer "Super Yellow" acting as n- and p-channel/emissive layers, respectively. Resulting HLETs operate at the lowest voltages reported to-date (<10 V) and combine high electron mobility (22 cm 2 /(V s)) with appreciable current on/off ratios (≈10 3 ) and an external quantum efficiency of 2 × 10 -2 % at 700 cd/m 2 . The charge injection, transport, and recombination mechanisms within this HLET architecture are discussed, and prospects for further performance enhancement are considered.

Process instrument monitoring for SNM solution surveillance

International Nuclear Information System (INIS)

Armatys, C.M.; Johnson, C.E.; Wagner, E.P.

1983-02-01

A process monitoring computer system at the Idaho Chemical Processing Plant (ICPP) is being used to evaluate nuclear fuel reprocessing plant data for Safeguards surveillance capabilities. The computer system was installed to collect data from the existing plant instruments and to evaluate what safeguards assurances can be provided to complement conventional accountability and physical protection measures. Movements of solutions containing special nuclear material (SNM) can be observed, activities associated with accountancy measurements (mixing, sampling, and bulk measurement) can be confirmed, and long-term storage of SNM solutions can be monitored to ensure containment. Special precautions must be taken, both in system design and operation to ensure adequate coverage of essential measured parameters and interpretation of process data, which can be comprised by instrument malfunctions or failures, unreliable data collection, or process activities that deviate from readily identified procedures. Experience at ICPP and prior evaluations at the Tokai reprocessing plant show that the use of process data can provide assurances that accountability measurement procedures are followed and SNM solutions are properly contained and can help confirm that SNM controls are in effect within a facility

Early Phase Process Evaluation: Industrial Practices

Directory of Open Access Journals (Sweden)

Zulfan Adi Putra

2016-09-01

Full Text Available Process route evaluation is a part of research and development (R&D works in an industrial chemical project life cycle. In this early phase, good process evaluation, including process synthesis and designs, provide guidance’s on the R&D project. The paper aimed to collect practical methods used in this early phase process route evaluation from author’s 10 years of industrial experiences.  The collected methods range from forward-backward process synthesis, functional process design, use of cost estimation, and applications of Monte Carlo simulation. Led by a good project management (e.g. via a stage-gate approach use of these methods have shown beneficial results. Some important results are strong arguments on whether or not the project will continue, as well as relevant technical and economic issues identified during this early phase process synthesis and design. Later on, these issues become guidance’s to the follow-up project, if it is continued.

Layout and Optics Solution for the LHC Insertion Upgrade Phase I

CERN Document Server

Fartoukh, S

2010-01-01

The main guidelines of the LHC IR upgrade Phase I project are the development of wider aperture (120 mm) and lower gradient (120 T/m) quadrupoles using the wellcharacterized Nb-Ti technology in order to build new inner triplets (IT) for the ATLAS and CMS experimental insertions, while minimizing the hardware modifications in the other parts of these insertions, in particular leaving unchanged the so-called "matching section" (MS) and "dispersion suppressor" (DS). While one of the initial goal was to squeeze the optics down to a B* of 25 cm, optics solutions with a B* of 30 cm are already at the edge of feasibility, both in terms of the IT and MS mechanical acceptance, gradients of the MS and DS quadrupole magnets, and correctability by the arc sextupoles of the huge chromatic aberrations generated at low B*. The layout of the new inner triplet and the corresponding injection and collision optics will be presented and analyzed in terms of aperture and chromatic correction.

Predictive modeling of nanoscale domain morphology in solution-processed organic thin films

Science.gov (United States)

Schaaf, Cyrus; Jenkins, Michael; Morehouse, Robell; Stanfield, Dane; McDowall, Stephen; Johnson, Brad L.; Patrick, David L.

2017-09-01

The electronic and optoelectronic properties of molecular semiconductor thin films are directly linked to their extrinsic nanoscale structural characteristics such as domain size and spatial distributions. In films prepared by common solution-phase deposition techniques such as spin casting and solvent-based printing, morphology is governed by a complex interrelated set of thermodynamic and kinetic factors that classical models fail to adequately capture, leaving them unable to provide much insight, let alone predictive design guidance for tailoring films with specific nanostructural characteristics. Here we introduce a comprehensive treatment of solution-based film formation enabling quantitative prediction of domain formation rates, coverage, and spacing statistics based on a small number of experimentally measureable parameters. The model combines a mean-field rate equation treatment of monomer aggregation kinetics with classical nucleation theory and a supersaturation-dependent critical nucleus size to solve for the quasi-two-dimensional temporally and spatially varying monomer concentration, nucleation rate, and other properties. Excellent agreement is observed with measured nucleation densities and interdomain radial distribution functions in polycrystalline tetracene films. Numerical solutions lead to a set of general design rules enabling predictive morphological control in solution-processed molecular crystalline films.

Effect of solution treatment temperature and cooling rate on the mechanical properties of tungsten heavy alloy

Energy Technology Data Exchange (ETDEWEB)

Kumari, Anjali, E-mail: anjalikumari1261@gmail.com; Prabhu, G.; Sankaranarayana, M.; Nandy, T.K.

2017-03-14

The present study investigates the effect of solution treatment temperature and cooling rate on mechanical properties of a tungsten heavy alloy (89.6W-6.2Ni-1.8Fe-2.4Co). In addition to water quenching, rapid argon quenching has been attempted in this study since it is a relatively cleaner process and it can be used in conjunction with vacuum treatment. Since in these alloys, there is a possibility of incomplete dissolution of intermetallics or segregation of impurities during heat treatment, which results in scatter in the mechanical properties, it was decided that the solution treatment temperature for both water and argon quenching would be varied from 1100 to 1250 °C in order to see its effect on the microstructure and mechanical properties. Solution treatment at varying temperatures followed by water quenching resulted in tensile strength ranging from 908 to 921 MPa and % elongation varied from 19% to 26%. On the other hand, the argon quenching heat treatment resulted in tensile strength in the range of 871–955 MPa and % elongation from 9% to 25%. No significant trend with respect to solution treatment temperature on tensile properties was seen in both argon and water quenched samples. % elongation to failure and impact values of water quenched specimens were better than those of argon quenched specimens for a given solution treatment temperature. The impact values appeared to improve with increasing solution treatment temperature in water quenched condition. The properties were correlated with underlying microstructure and fractographs of the failed specimens. The study showed the argon quenching may not be appropriate for the heat treatment of heavy alloys since it results in inferior mechanical properties as compared to water quenching.

Transparent megahertz circuits from solution-processed composite thin films.

Science.gov (United States)

Liu, Xingqiang; Wan, Da; Wu, Yun; Xiao, Xiangheng; Guo, Shishang; Jiang, Changzhong; Li, Jinchai; Chen, Tangsheng; Duan, Xiangfeng; Fan, Zhiyong; Liao, Lei

2016-04-21

Solution-processed amorphous oxide semiconductors have attracted considerable interest in large-area transparent electronics. However, due to its relative low carrier mobility (∼10 cm(2) V(-1) s(-1)), the demonstrated circuit performance has been limited to 800 kHz or less. Herein, we report solution-processed high-speed thin-film transistors (TFTs) and integrated circuits with an operation frequency beyond the megahertz region on 4 inch glass. The TFTs can be fabricated from an amorphous indium gallium zinc oxide/single-walled carbon nanotube (a-IGZO/SWNT) composite thin film with high yield and high carrier mobility of >70 cm(2) V(-1) s(-1). On-chip microwave measurements demonstrate that these TFTs can deliver an unprecedented operation frequency in solution-processed semiconductors, including an extrinsic cut-off frequency (f(T) = 102 MHz) and a maximum oscillation frequency (f(max) = 122 MHz). Ring oscillators further demonstrated an oscillation frequency of 4.13 MHz, for the first time, realizing megahertz circuit operation from solution-processed semiconductors. Our studies represent an important step toward high-speed solution-processed thin film electronics.

New mechanism for autocatalytic decomposition of H2CO3 in the vapor phase.

Science.gov (United States)

Ghoshal, Sourav; Hazra, Montu K

2014-04-03

In this article, we present high level ab initio calculations investigating the energetics of a new autocatalytic decomposition mechanism for carbonic acid (H2CO3) in the vapor phase. The calculation have been performed at the MP2 level of theory in conjunction with aug-cc-pVDZ, aug-cc-pVTZ, and 6-311++G(3df,3pd) basis sets as well as at the CCSD(T)/aug-cc-pVTZ level. The present study suggests that this new decomposition mechanism is effectively a near-barrierless process at room temperature and makes vapor phase of H2CO3 unstable even in the absence of water molecules. Our calculation at the MP2/aug-cc-pVTZ level predicts that the effective barrier, defined as the difference between the zero-point vibrational energy (ZPE) corrected energy of the transition state and the total energy of the isolated starting reactants in terms of bimolecular encounters, is nearly zero for the autocatalytic decomposition mechanism. The results at the CCSD(T)/aug-cc-pVTZ level of calculations suggest that the effective barrier, as defined above, is sensitive to some extent to the levels of calculations used, nevertheless, we find that the effective barrier height predicted at the CCSD(T)/aug-cc-pVTZ level is very small or in other words the autocatalytic decomposition mechanism presented in this work is a near-barrierless process as mentioned above. Thus, we suggest that this new autocatalytic decomposition mechanism has to be considered as the primary mechanism for the decomposition of carbonic acid, especially at its source, where the vapor phase concentration of H2CO3 molecules reaches its highest levels.

Calculation of period processing solution syrup in vacuum apparatus

Directory of Open Access Journals (Sweden)

A. A. Slavyanskii

2016-01-01

Full Text Available Important and crucial element in the management of the technological flow of production of sugar product standards is the period of time the enrichment of massecuite, since its neutralization in the process of crystal formation in vacuum apparatus, excess sugar solution. Although currently proposed and implemented in the industry, including as a front-end accompany the process, a number of ways in the real world sugar production in many cases have to resort to the services of an experienced operator. It is obvious that in any case it is necessary to have a surround-dependent glucose solution data on time for the excess sugar solution into the vacuum apparatus. With regard to the period of the enrichment of depleted sucrose solution are entered into this substance excess sucrose solution, it should be noted that this problem is theoretically still insufficiently developed. It is obvious that for practical purposes it is desirable to have a simple and convenient for engineering calculation of sugar processing time dependencies of the specified volume of water from the operating parameters of the process (the required concentration of sucrose, temperature of the solution stirring. The problem is the quantitative analysis of sucrose crystallization in vacuum apparatus, including the timing of enrichment solution to the excess syrup, period of time processing massecuite total this apparatus has been investigated in many works. However, due to its importance to the task of obtaining commercial sugar high standards this issue required further in-depth examination. In the article to support the enrichment process solution sucrose due to neutralize this solvent system in vacuum apparatus, from the standpoint of diffusion theory provides a more reasonable compared to known so far, quantitative analysis of this process. Where as sucrose crystals team are considering a system of balls, uniformly distributed in vacuum apparatus. On the basis of the solution

Phase study of titanium dioxide nanoparticle prepared via sol-gel process

Science.gov (United States)

Oladeji Araoyinbo, Alaba; Bakri Abdullah, Mohd Mustafa Al; Salleh, Mohd Arif Anuar Mohd; Aziz, Nurul Nadia Abdul; Iskandar Azmi, Azwan

2018-03-01

In this study, titanium dioxide nanoparticles have been prepared via sol-gel process using titanium tetraisopropoxide as a precursor with hydrochloric acid as a catalyst, and ethanol with deionized water as solvents. The value of pH used is set to 3, 7 and 8. The sols obtained were dried at 100 °C for 1 hr and calcined at 350, 550, and 750 °C for 3 hrs to observe the phase transformation of titanium dioxide nanoparticle. The samples were characterized by x-ray diffraction and field emission scanning electron microscope. The morphology analysis is obtained from field emission scanning electron microscope. The phase transformation was investigated by x-ray diffraction. It was found that the pH of the solution affect the agglomeration of titanium dioxide particle. The x-ray diffraction pattern of titanium dioxide shows the anatase phase most abundant at temperature of 350 °C. At temperature of 550 °C the anatase and rutile phase were present. At temperature of 750 °C the rutile phase was the most abundant for pH 3, 7 and 8. It was confirmed that at higher temperature the rutile phase which is the stable phase are mostly present.

Gamma activity coupled to alpha phase as a mechanism for top-down controlled gating

NARCIS (Netherlands)

Bonnefond, M.; Jensen, O.

2015-01-01

Coupling between neural oscillations in different frequency bands has been proposed to coordinate neural processing. In particular, gamma power coupled to alpha phase is proposed to reflect gating of information in the visual system but the existence of such a mechanism remains untested. Here, we

The eigenvalue problem in phase space.

Science.gov (United States)

Cohen, Leon

2018-06-30

We formulate the standard quantum mechanical eigenvalue problem in quantum phase space. The equation obtained involves the c-function that corresponds to the quantum operator. We use the Wigner distribution for the phase space function. We argue that the phase space eigenvalue equation obtained has, in addition to the proper solutions, improper solutions. That is, solutions for which no wave function exists which could generate the distribution. We discuss the conditions for ascertaining whether a position momentum function is a proper phase space distribution. We call these conditions psi-representability conditions, and show that if these conditions are imposed, one extracts the correct phase space eigenfunctions. We also derive the phase space eigenvalue equation for arbitrary phase space distributions functions. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Al-Cu-Li and Al-Mg-Li alloys: Phase composition, texture, and anisotropy of mechanical properties (Review)

Science.gov (United States)

Betsofen, S. Ya.; Antipov, V. V.; Knyazev, M. I.

2016-04-01

The results of studying the phase transformations, the texture formation, and the anisotropy of the mechanical properties in Al-Cu-Li and Al-Mg-Li alloys are generalized. A technique and equations are developed to calculate the amounts of the S1 (Al2MgLi), T1 (Al2CuLi), and δ' (Al3Li) phases. The fraction of the δ' phase in Al-Cu-Li alloys is shown to be significantly higher than in Al-Mg-Li alloys. Therefore, the role of the T1 phase in the hardening of Al-Cu-Li alloys is thought to be overestimated, especially in alloys with more than 1.5% Li. A new model is proposed to describe the hardening of Al-Cu-Li alloys upon aging, and the results obtained with this model agree well with the experimental data. A texture, which is analogous to that in aluminum alloys, is shown to form in sheets semiproducts made of Al-Cu-Li and Al-Mg-Li alloys. The more pronounced anisotropy of the properties of lithium-containing aluminum alloys is caused by a significant fraction of the ordered coherent δ' phase, the deformation mechanism in which differs radically from that in the solid solution.

Effect of zirconia content and powder processing mechanical properties of gelcasted ZTA composite

International Nuclear Information System (INIS)

Khoshkalam, M.; Faghihi-Sani, M.A.; Nojoomi, A.

2013-01-01

Addition of fine zirconia particles in the alumina matrix in order to produce ZTA composite is a well-known method for improving the mechanical properties of alumina ceramics such as flexural strength and fracture toughness. Increasing homogeneity and reducing alumina grain size are two key factors for achieving proper mechanical properties in this ceramic matrix composite. In this work two batches of ZTA powder precursor were prepared through mixing of alumina and zirconia by ball milling and in situ synthesis of ZTA composite via solution combustion method. The bending strength testing samples were fabricated through gel-casting process. The effects of different powder processing methods as well as zirconia contents on microstructural homogeneity and mechanical properties of ZTA composites were investigated. The samples produced by solution combustion synthesized powder yielded higher homogeneity, finer microstructure and higher flexural strength. Results showed an upswing in the fracture toughness for the synthesized samples even up to 20 vol% zirconia, while the mixed samples depicted optimum fracture toughness in 10 vol% zirconia content. (author)

Study of the crystallographic phase change on copper (I) selenide thin films prepared through chemical bath deposition by varying the pH of the solution

Energy Technology Data Exchange (ETDEWEB)

Sandoval-Paz, M.G., E-mail: myrnasandoval@udec.cl [Departament of Physics, Faculty of Physical Sciences and Mathematics, University of Concepcion, Box 160-C, Concepción (Chile); Rodríguez, C.A. [Department of Materials Engineering, Faculty of Engineering, University of Concepción, Edmundo Larenas 270, Concepción 4070409 (Chile); Porcile-Saavedra, P.F. [Departament of Physics, Faculty of Physical Sciences and Mathematics, University of Concepcion, Box 160-C, Concepción (Chile); Trejo-Cruz, C. [Department of Physics, Faculty of Science, University of Biobío, Avenue Collao 1202, Box 5C, Concepción 4051381 (Chile)

2016-07-15

Copper (I) selenide thin films with orthorhombic and cubic structure were deposited on glass substrates by using the chemical bath deposition technique. The effects of the solution pH on the films growth and subsequently the structural, optical and electrical properties of the films were studied. Films with orthorhombic structure were obtained from baths wherein both metal complex and hydroxide coexist; while films with cubic structure were obtained from baths where the metal hydroxide there is no present. The structural modifications are accompanied by changes in bandgap energy, morphology and electrical resistivity of the films. - Graphical abstract: “Study of the crystallographic phase change on copper (I) selenide thin films prepared through chemical bath deposition by varying the pH of the solution” by M. G. Sandoval-Paz, C. A. Rodríguez, P. F. Porcile-Saavedra, C. Trejo-Cruz. Display Omitted - Highlights: • Copper (I) selenide thin films were obtained by chemical bath deposition. • Orthorhombic to cubic phase change was induced by varying the reaction solution pH. • Orthorhombic phase is obtained mainly from a hydroxides cluster mechanism. • Cubic phase is obtained mainly from an ion by ion mechanism. • Structural, optical and electrical properties are presented as a function of pH.

Phase relations and Gibbs energies of spinel phases and solid solutions in the system Mg-Rh-O

Energy Technology Data Exchange (ETDEWEB)

Jacob, K.T., E-mail: katob@materials.iisc.ernet.in [Department of Materials Engineering, Indian Institute of Science, Bangalore 560 012 (India); Prusty, Debadutta [Department of Materials Engineering, Indian Institute of Science, Bangalore 560 012 (India); Kale, G.M. [Institute for Materials Research, University of Leeds, Leeds, LS2 9JT (United Kingdom)

2012-02-05

Highlights: Black-Right-Pointing-Pointer Refinement of phase diagram for the system Mg-Rh-O and thermodynamic data for spinel compounds MgRh{sub 2}O{sub 4} and Mg{sub 2}RhO{sub 4} is presented. Black-Right-Pointing-Pointer A solid-state electrochemical cell is used for thermodynamic measurement. Black-Right-Pointing-Pointer An advanced design of the solid-state electrochemical cell incorporating buffer electrodes is deployed to minimize polarization of working electrode. Black-Right-Pointing-Pointer Regular solution model for the spinel solid solution MgRh{sub 2}O{sub 4} - Mg{sub 2}RhO{sub 4} based on ideal mixing of cations on the octahedral site is proposed. Black-Right-Pointing-Pointer Factors responsible for stabilization of tetravalent rhodium in spinel compounds are identified. - Abstract: Pure stoichiometric MgRh{sub 2}O{sub 4} could not be prepared by solid state reaction from an equimolar mixture of MgO and Rh{sub 2}O{sub 3} in air. The spinel phase formed always contained excess of Mg and traces of Rh or Rh{sub 2}O{sub 3}. The spinel phase can be considered as a solid solution of Mg{sub 2}RhO{sub 4} in MgRh{sub 2}O{sub 4}. The compositions of the spinel solid solution in equilibrium with different phases in the ternary system Mg-Rh-O were determined by electron probe microanalysis. The oxygen potential established by the equilibrium between Rh + MgO + Mg{sub 1+x}Rh{sub 2-x}O{sub 4} was measured as a function of temperature using a solid-state cell incorporating yttria-stabilized zirconia as an electrolyte and pure oxygen at 0.1 MPa as the reference electrode. To avoid polarization of the working electrode during the measurements, an improved design of the cell with a buffer electrode was used. The standard Gibbs energies of formation of MgRh{sub 2}O{sub 4} and Mg{sub 2}RhO{sub 4} were deduced from the measured electromotive force (e.m.f.) by invoking a model for the spinel solid solution. The parameters of the model were optimized using the measured

Controlling solution-phase polymer aggregation with molecular weight and solvent additives to optimize polymer-fullerene bulk heterojunction solar cells

KAUST Repository

Bartelt, Jonathan A.; Douglas, Jessica D.; Mateker, William R.; El Labban, Abdulrahman; Tassone, Christopher J.; Toney, Michael F.; Fré chet, Jean Mj J; Beaujuge, Pierre; McGehee, Michael D.

2014-01-01

The bulk heterojunction (BHJ) solar cell performance of many polymers depends on the polymer molecular weight (M n) and the solvent additive(s) used for solution processing. However, the mechanism that causes these dependencies is not well

Electron spectra and mechanism of complexing of uranyl nitrate in water-acetone solutions

International Nuclear Information System (INIS)

Zazhogin, A.A.; Zazhogin, A.P.; Komyak, A.I.; Serafimovich, A.I.

2003-01-01

Based on the analysis of the luminescence and electronic absorption spectra, the processes of complexing in an aqueous solution of UO 2 (NO 3 ) 2 ·6H 2 O with small additions of acetone have been studied. In a pure aqueous solution, uranyl exists as the complex UO 2 ·5H 2 O. It is shown that the addition of acetone to the solution leads to the displacement of some water molecules out of the first coordination sphere of uranyl and the formation of the uranyl nitrate dihydrate complexes UO 2 (NO 3 ) 2 ·2H 2 O. It has been established that the stability of these complexes is determined by the decrease in the water activity and in the degree of hydration of uranyl and nitrate, which is the result of the local increase in the concentration of acetone molecules (due to their hydrophobicity) in the regions of the solution where uranyl and nitrate ions are found. The experimental facts supported the mechanism proposed are presented. (authors)

Removal of ammonia solutions used in catalytic wet oxidation processes.

Science.gov (United States)

Hung, Chang Mao; Lou, Jie Chung; Lin, Chia Hua

2003-08-01

Ammonia (NH(3)) is an important product used in the chemical industry, and is common place in industrial wastewater. Industrial wastewater containing ammonia is generally either toxic or has concentrations or temperatures such that direct biological treatment is unfeasible. This investigation used aqueous solutions containing more of ammonia for catalytic liquid-phase oxidation in a trickle-bed reactor (TBR) based on Cu/La/Ce composite catalysts, prepared by co-precipitation of Cu(NO(3))(2), La(NO(3))(2), and Ce(NO(3))(3) at 7:2:1 molar concentrations. The experimental results indicated that the ammonia conversion of the wet oxidation in the presence of the Cu/La/Ce composite catalysts was determined by the Cu/La/Ce catalyst. Minimal ammonia was removed from the solution by the wet oxidation in the absence of any catalyst, while approximately 91% ammonia removal was achieved by wet oxidation over the Cu/La/Ce catalyst at 230 degrees C with oxygen partial pressure of 2.0 MPa. Furthermore, the effluent streams were conducted at a liquid hourly space velocity of under 9 h(-1) in the wet catalytic processes, and a reaction pathway was found linking the oxidizing ammonia to nitric oxide, nitrogen and water. The solution contained by-products, including nitrates and nitrites. Nitrite selectivity was minimized and ammonia removal maximized when the feed ammonia solution had a pH of around 12.0.

Electromagnetic processes during phase commutation in field regulated reluctance machine

Science.gov (United States)

Shishkov, A. N.; Sychev, D. A.; Zemlyansky, A. A.; Krupnova, M. N.; Funk, T. A.; Ishmet'eva, V. D.

2018-03-01

The processes of currents switching in stator windings have been explained by the existence of the electromagnetic torque ripples in the electric drive with the field-regulated reluctance machine. The maximum value of ripples in the open loop control system for the six-phase machine can reach 20 percent from the developed electromagnetic torque. This method allows one to make calculation of ripple spike towards average torque developed by the electromotor for the different number of phases. Application of a trapezoidal form of current at six phases became the solution. In case of a less number of phases than six, a ripple spike considerably increases, which is inadmissible. On the other hand, increasing the number of phases tends to the increase of the semiconductor inverter external dimensions based on the inconspicuous decreasing of a ripple spike. The creation and usage of high-speed control loops of current (HCLC) have been recommended for a reduction of the electromagnetic torque’s ripple level, as well as the appliance of positive current feedback in switching phase currents. This decision allowed one to receive a mean value of the torque more than 10%, compared to system without change, to reduce greatly ripple spike of the electromagnetic torque. The possibility of the electric drive effective operation with FRRM in emergency operation has been shown.

Game Theoretic Problems in Network Economics and Mechanism Design Solutions

CERN Document Server

Narahari, Y; Narayanam, Ramasuri; Prakash, Hastagiri

2009-01-01

Explores game theoretic modeling and mechanism design for problem solving in Internet and network economics. This monograph contains an exposition of representative game theoretic problems in three different network economics situations and a systematic exploration of mechanism design solutions to these problems.

Phases definition in marketing export process

OpenAIRE

Rajković Dragan; Kokić Miljko

2004-01-01

The result of export marketing process depends on its five phases. The first phase-revision of export capacities, inner view on advantages and defects of company concerning export possibilities. The second phase-identification of export strategy market penetration. The forth phase-preparing for the marketing campaign (action). The fifth phase-carrying out the above mentioned activities. This study shows the structure and contents of the mentioned phases. At the end, export marketing analyzed ...

Dual-Band Modulation of Visible and Near-Infrared Light Transmittance in an All-Solution-Processed Hybrid Micro-Nano Composite Film.

Science.gov (United States)

Liang, Xiao; Chen, Mei; Guo, Shumeng; Zhang, Lanying; Li, Fasheng; Yang, Huai

2017-11-22

Smart windows with controllable visible and near-infrared light transmittance can significantly improve the building's energy efficiency and inhabitant comfort. However, most of the current smart window technology cannot achieve the target of ideal solar control. Herein, we present a novel all-solution-processed hybrid micronano composite smart material that have four optical states to separately modulate the visible and NIR light transmittance through voltage and temperature, respectively. This dual-band optical modulation was achieved by constructing a phase-separated polymer framework, which contains the microsized liquid crystals domains with a negative dielectric constant and tungsten-doped vanadium dioxide (W-VO 2 ) nanocrystals (NCs). The film with 2.5 wt % W-VO 2 NCs exhibits transparency at normal condition, and the passage of visible light can be reversibly and actively regulated between 60.8% and 1.3% by external applied voltage. Also, the transmittance of NIR light can be reversibly and passively modulated between 59.4% and 41.2% by temperature. Besides, the film also features easy all-solution processability, fast electro-optical (E-O) response time, high mechanical strength, and long-term stability. The as-prepared film provides new opportunities for next-generation smart window technology, and the proposed strategy is conductive to engineering novel hybrid inorganic-organic functional matters.

Phase field simulations of ice crystal growth in sugar solutions

NARCIS (Netherlands)

Sman, Van Der R.G.M.

2016-01-01

We present the first model ever, that describes explicitly ice crystal growth in a sugar solution during freezing. This 2-D model uses the phase field method, supplemented with realistic, and predictive theories on the thermodynamics and (diffusion) kinetics of this food system. We have to make

Fundamental incorporation of the density change during melting of a confined phase change material

Science.gov (United States)

Hernández, Ernesto M.; Otero, José A.

2018-02-01

The modeling of thermal diffusion processes taking place in a phase change material presents a challenge when the dynamics of the phase transition is coupled to the mechanical properties of the container. Thermo-mechanical models have been developed by several authors, however, it will be shown that these models only explain the phase transition dynamics at low pressures when the density of each phase experiences negligible changes. In our proposal, a new energy-mass balance equation at the interface is derived and found to be a consequence of mass conservation. The density change experienced in each phase is predicted by the proposed formulation of the problem. Numerical and semi-analytical solutions to the proposed model are presented for an example on a high temperature phase change material. The solutions to the models presented by other authors are observed to be well-behaved close to the isobaric limit. However, compared to the results obtained from our model, the change in the fusion temperature, latent heat, and absolute pressure is found to be greatly overestimated by other proposals when the phase transition is studied close to the isochoric regime.

Thermodynamic nonequilibrium phase change behavior and thermal properties of biological solutions for cryobiology applications.

Science.gov (United States)

Han, Bumsoo; Bischof, John C

2004-04-01

Understanding the phase change behavior of biomaterials during freezing/thawing including their thermal properties at low temperatures is essential to design and improve cryobiology applications such as cryopreservation and cryosurgery. However, knowledge of phase change behavior and thermal properties of various biomaterials is still incomplete, especially at cryogenic temperatures (solutions--either water-NaCl or phosphate buffered saline (PBS)--with various chemical additives were investigated. The chemical additives studied are glycerol and raffinose as CPAs, an AFP (Type III, molecular weight = 6500), and NaCl as a cryosurgical adjuvant. The phase change behavior was investigated using a differential scanning calorimeter (DSC) and a cryomicroscope. The specific and latent heat of these solutions were also measured with the DSC. The saline solutions have two distinct phase changes--water/ice and eutectic phase changes. During freezing, eutectic solidification of both water-NaCl and PBS are significantly supercooled below their thermodynamic equilibrium eutectic temperatures. However, their melting temperatures are close to thermodynamic equilibrium during thawing. These eutectic phase changes disappear when even a small amount (0.1 M glycerol) of CPA was added, but they are still observed after the addition of an AFP. The specific heats of these solutions are close to that of ice at very low temperatures (< or = -100 degrees C) regardless of the additives, but they increase between -100 degrees C and -30 degrees C with the addition of CPAs. The amount of latent heat, which is evaluated with sample weight, generally decreases with the addition of the additives, but can be normalized to approximately 300 J/g based on the weight of water which participates in the phase change. This illustrates that thermal properties, especially latent heat, of a biomaterial should be evaluated based on the understanding of its phase change behavior. The results of the present

Characterization of phase changes during fabrication of copper alloys, crystalline and non-crystalline, prepared by mechanical alloying

Directory of Open Access Journals (Sweden)

Paula Rojas

2016-09-01

Full Text Available The manufacture of alloys in solid state has many differences with the conventional melting (casting process. In the case of high energy milling or mechanical alloying, phase transformations of the raw materials are promoted by a large amount of energy that is introduced by impact with the grinding medium; there is no melting, but the microstructural changes go from microstructural refinement to amorphization in solid state. This work studies the behavior of pure metals (Cu and Ni, and different binary alloys (Cu-Ni and Cu-Zr, under the same milling/mechanical alloying conditions. After high-energy milling, X ray diffraction (XRD patterns were analyzed to determine changes in the lattice parameter and find both microstrain and crystallite sizes, which were first calculated using the Williamson-Hall (W-H method and then compared with the transmission electron microscope (TEM images. Calculations showed a relatively appropriate approach to observations with TEM; however, in general, TEM observations detect heterogeneities, which are not considered for the W-H method. As for results, in the set of pure metals, we show that pure nickel undergoes more microstrain deformations, and is more abrasive than copper (and copper alloys. In binary systems, there was a complete solid solution in the Cu-Ni system and a glass-forming ability for the Cu-Zr, as a function of the Zr content. Mathematical methods cannot be applied when the systems have amorphization because there are no equations representing this process during milling. A general conclusion suggests that, under the same milling conditions, results are very different due to the significant impact of the composition: nickel easily forms a solid solution, while with a higher zirconium content there is a higher degree of glassforming ability.

Fabrication mechanism of FeSe superconductors with high-energy ball milling aided sintering process

International Nuclear Information System (INIS)

Zhang, Shengnan; Liu, Jixing; Feng, Jianqing; Wang, Yao; Ma, Xiaobo; Li, Chengshan; Zhang, Pingxiang

2015-01-01

FeSe Superconducting bulks with high content of superconducting PbO-type β-FeSe phase were prepared with high-energy ball milling (HEBM) aided sintering process. During this process, precursor powders with certain Fe/Se ratio were ball milled first then sintered. The influences of HEBM process as well as initial Fe/Se ratio on the phase evolution process were systematically discussed. With HEBM process and proper initial Fe/Se ratio, the formation of non-superconducting hexagonal δ-FeSe phase were effectively avoided. FeSe bulk with the critical temperature of 9.0 K was obtained through a simple one-step sintering process with lower sintering temperature. Meanwhile, the phase evolution mechanism of the HEBM precursor powders during sintering was deduced based on both the thermodynamic analysis and step-by-step sintering results. The key function of the HEBM process was to provide a high uniformity of chemical composition distribution, thus to successfully avoide the formation of intermediate product during sintering, including FeSe 2 and Fe 7 Se 8 . Therefore, the fundamental principal for the synthesis of FeSe superconductors were concluded as: HEBM aided sintering process, with the sintering temperature of >635 °C and a slow cooling process. - Highlights: • A novel synthesis technique was developed for FeSe based superconductors. • FeSe bulks with high Tc and high β-FeSe phase content has been obtained. • Phase evolution process for the HEBM aided sintering process was proposed

Aging Behaviour and Mechanical Performance of 18-Ni 300 Steel Processed by Selective Laser Melting

Directory of Open Access Journals (Sweden)

Riccardo Casati

2016-09-01

Full Text Available An 18-Ni 300 grade maraging steel was processed by selective laser melting and an investigation was carried out on microstructural and mechanical behaviour as a function of aging condition. Owing to the rapid cooling rate, the as-built alloy featured a full potential for precipitate strengthening, without the need of a solution treatment prior to aging. The amount of reversed austenite found in the microstructure increased after aging and revealed to depend on aging temperature and time. Similarly to the corresponding wrought counterpart, also in the selective laser-melted 18-Ni 300 alloy, aging promoted a dramatic increase in strength with respect to the as-built condition and a drop in tensile ductility. No systematic changes were found in tensile properties as a function of measured amount of austenite. It is proposed that the submicrometric structure and the phase distribution inherited by the rapid solidification condition brought by selective laser melting are such that changes in tensile strength and ductility are mainly governed by the effects brought by the strengthening precipitates, whereas the concurrent reversion of the γ-Fe phase in different amounts seems to play a minor role.

Solution-processed organic thermoelectric materials exhibiting doping-concentration-dependent polarity.

Science.gov (United States)

Hwang, Sunbin; Potscavage, William J; Yang, Yu Seok; Park, In Seob; Matsushima, Toshinori; Adachi, Chihaya

2016-10-26

Recent progress in conducting polymer-based organic thermoelectric generators (OTEGs) has resulted in high performance due to high Seebeck coefficient, high electrical conductivity (σ), and low thermal conductivity obtained by chemically controlling the materials's redox levels. In addition to improving the properties of individual OTEGs to obtain high performance, the development of solution processes for the fabrication of OTEG modules is necessary to realize large thermoelectric voltage and low-cost mass production. However, the scarcity of good candidates for soluble organic n-type materials limits the use of π-leg module structures consisting of complementary elements of p- and n-type materials because of unbalanced transport coefficients that lead to power losses. In particular, the extremely low σ of n-type materials compared with that of p-type materials is a serious challenge. In this study, poly(pyridinium phenylene) (P(PymPh)) was tested as an n-type semiconductor in solution-processed OTEGs, and the carrier density was controlled by a solution-based chemical doping process using the dopant sodium naphthalenide, a well-known reductant. The electronic structures and doping mechanism of P(PymPh) were explored based on the changes in UV-Vis-IR absorption, ultraviolet photoelectron, and X-ray photoelectron spectra. By controlling the dopant concentration, we demonstrate a maximum n-type power factor of 0.81 μW m -1 K -2 with high σ, and at higher doping concentrations, a switch from n-type to p-type TE operation. This is one of the first cases of a switch in polarity just by increasing the concentration of the reductant and may open a new route for simplified fabrication of complementary organic layers.

Phase Transitions in Mechanically Milled Mn-Al-C Permanent Magnets

Directory of Open Access Journals (Sweden)

Michael J. Lucis

2014-04-01

Full Text Available Mn-Al powders were prepared by rapid solidification followed by high-energy mechanical milling. The rapid solidification resulted in single-phase ε. The milling was performed in both the ε phase and the τ phase, with the τ-phase formation accomplished through a heat treatment at 500 °C for 10 min. For the ε-milled samples, the conversion of the ε to the τ phase was accomplished after milling via the same heat treatment. Mechanical milling induced a significant increase in coercivity in both cases, reaching 4.5 kOe and 4.1 kOe, respectively, followed by a decrease upon further milling. The increase in coercivity was the result of grain refinement induced by the high-energy mechanical milling. Additionally, in both cases a loss in magnetization was observed. Milling in the ε phase showed a smaller decrease in the magnetization due to a higher content of the τ phase. The loss in magnetization was attributed to a stress-induced transition to the equilibrium phases, as no site disorder or oxidation was observed. Surfactant-assisted milling in oleic acid also improved coercivity, but in this case values reached >4 kOe and remained stable at least through 32 h of milling.

The role of high-level processes for oscillatory phase entrainment to speech sound

Directory of Open Access Journals (Sweden)

Benedikt eZoefel

2015-12-01

Full Text Available Constantly bombarded with input, the brain has the need to filter out relevant information while ignoring the irrelevant rest. A powerful tool may be represented by neural oscillations which entrain their high-excitability phase to important input while their low-excitability phase attenuates irrelevant information. Indeed, the alignment between brain oscillations and speech improves intelligibility and helps dissociating speakers during a cocktail party. Although well-investigated, the contribution of low- and high-level processes to phase entrainment to speech sound has only recently begun to be understood. Here, we review those findings, and concentrate on three main results: (1 Phase entrainment to speech sound is modulated by attention or predictions, likely supported by top-down signals and indicating higher-level processes involved in the brain’s adjustment to speech. (2 As phase entrainment to speech can be observed without systematic fluctuations in sound amplitude or spectral content, it does not only reflect a passive steady-state ringing of the cochlea, but entails a higher-level process. (3 The role of intelligibility for phase entrainment is debated. Recent results suggest that intelligibility modulates the behavioral consequences of entrainment, rather than directly affecting the strength of entrainment in auditory regions. We conclude that phase entrainment to speech reflects a sophisticated mechanism: Several high-level processes interact to optimally align neural oscillations with predicted events of high relevance, even when they are hidden in a continuous stream of background noise.

Circadian Clock Synchronization of the Cell Cycle in Zebrafish Occurs through a Gating Mechanism Rather Than a Period-phase Locking Process.

Science.gov (United States)

Laranjeiro, Ricardo; Tamai, T Katherine; Letton, William; Hamilton, Noémie; Whitmore, David

2018-04-01

Studies from a number of model systems have shown that the circadian clock controls expression of key cell cycle checkpoints, thus providing permissive or inhibitory windows in which specific cell cycle events can occur. However, a major question remains: Is the clock actually regulating the cell cycle through such a gating mechanism or, alternatively, is there a coupling process that controls the speed of cell cycle progression? Using our light-responsive zebrafish cell lines, we address this issue directly by synchronizing the cell cycle in culture simply by changing the entraining light-dark (LD) cycle in the incubator without the need for pharmacological intervention. Our results show that the cell cycle rapidly reentrains to a shifted LD cycle within 36 h, with changes in p21 expression and subsequent S phase timing occurring within the first few hours of resetting. Reentrainment of mitosis appears to lag S phase resetting by 1 circadian cycle. The range of entrainment of the zebrafish clock to differing LD cycles is large, from 16 to 32 hour periods. We exploited this feature to explore cell cycle entrainment at both the population and single cell levels. At the population level, cell cycle length is shortened or lengthened under corresponding T-cycles, suggesting that a 1:1 coupling mechanism is capable of either speeding up or slowing down the cell cycle. However, analysis at the single cell level reveals that this, in fact, is not true and that a gating mechanism is the fundamental method of timed cell cycle regulation in zebrafish. Cell cycle length at the single cell level is virtually unaltered with varying T-cycles.

Liquid-Phase Packaging of a Glucose Oxidase Solution with Parylene Direct Encapsulation and an Ultraviolet Curing Adhesive Cover for Glucose Sensors

OpenAIRE

Seiichi Takamatsu; Hisanori Takano; Nguyen Binh-Khiem; Tomoyuki Takahata; Eiji Iwase; Kiyoshi Matsumoto; Isao Shimoyama

2010-01-01

We have developed a package for disposable glucose sensor chips using Parylene encapsulation of a glucose oxidase solution in the liquid phase and a cover structure made of an ultraviolet (UV) curable adhesive. Parylene was directly deposited onto a small volume (1 μL) of glucose oxidase solution through chemical vapor deposition. The cover and reaction chamber were constructed on Parylene film using a UV-curable adhesive and photolithography. The package was processed at room temperature to ...

Pattern Formation During Phase Separation of Polymer-Ionic Liquid Co-Solutions

Science.gov (United States)

Meng, Zhiyong; Osuji, Chinedum

2010-03-01

Co-solutions of polystyrene (PS) with a 1-butyl-3-methylimidazolium based ionic liquid (IL) in DMF phase separated into IL-rich and PS-rich domains on solvent evaporation. Over a limited range of polymer molecular weights and substrate temperatures, a variety of striped and cellular or polygonal structures were found on the resulting film surface, as visualized using bright-field and phase-contrast optical microscopy. This effect appears to be due to a Benard-Marangoni instability at the free surface of the liquid film as it undergoes evaporation, setting up convection rolls inside the fluid which become locked in place as the system vitrifies on solvent removal. Differential scanning calorimetry shows that the IL does not significantly plasticize the polymer, suggesting that the viscosity of the polystyrene solution itself controls the formation of this instability.

The Precipitation Processes and Mechanical Properties of Aged Inconel 718 Alloy After Annealing

Directory of Open Access Journals (Sweden)

Maj P.

2017-09-01

Full Text Available Inconel 718 is a precipitation hardenable nickel-iron based superalloy. It has exceptionally high strength and ductility compared to other metallic materials. This is due to intense precipitation of the γ’ and γ” strengthening phases in the temperature range 650-850°C. The main purpose of the authors was to analyze the aging process in Inconel 718 obtained in accordance with AMS 5596, and its effect on the mechanical properties. Tensile and hardness tests were used to evaluate the mechanical properties, in the initial aging process and after reheating, as a function of temperature and time respectively in the ranges 650°-900°C and 5-480 min. In addition, to link the mechanical properties with the microstructure transmission microscopy observations were carried out in selected specimens. As a result, factors influencing the microstructure changes at various stages of strengthening were observed. The authors found that the γ’’ phase nucleates mostly homogenously in the temperature range 650-750°C, causing the greatest increase in strength. On the other hand, the γ’ and δ phases are formed heterogeneously at 850°C or after longer annealing in 800°C, which may weaken the material.

Numerical method for solution of transient, homogeneous, equilibrium, two-phase flows in one space dimension

International Nuclear Information System (INIS)

Shin, Y.W.; Wiedermann, A.H.

1979-10-01

A solution method is presented for transient, homogeneous, equilibrium, two-phase flows of a single-component fluid in one space dimension. The method combines a direct finite-difference procedure and the method of characteristics. The finite-difference procedure solves the interior points of the computing domain; the boundary information is provided by a separate procedure based on the characteristics theory. The solution procedure for boundary points requires information in addition to the physical boundary conditions. This additional information is obtained by a new procedure involving integration of characteristics in the hodograph plane. Sample problems involving various combinations of basic boundary types are calculated for two-phase water/steam mixtures and single-phase nitrogen gas, and compared with independent method-of-characteristics solutions using very fine characteristic mesh. In all cases, excellent agreement is demonstrated

Theory of phase-slip processes in thin and dirty current-carrying superconducting wires: Deviations from local equilibrium

International Nuclear Information System (INIS)

Kraehenbuehl, Y.

1983-01-01

Oscillatory phase-slip solution of a set of integrodifferential equations describing time-dependent processes in dirty superconductors in the Ginzburg-Landau regime are found numerically very near Tsub(c). Deviations from local equilibrium improve the agreement with observed V-I curves. (orig.)

Electrochemical studies of Copper, Tantalum and Tantalum Nitride surfaces in aqueous solutions for applications in chemical-mechanical and electrochemical-mechanical planarization

Science.gov (United States)

Sulyma, Christopher Michael

This report will investigate fundamental properties of materials involved in integrated circuit (IC) manufacturing. Individual materials (one at a time) are studied in different electrochemical environmental solutions to better understand the kinetics associated with the polishing process. Each system tries to simulate a real CMP environment in order to compare our findings with what is currently used in industry. To accomplish this, a variety of techniques are used. The voltage pulse modulation technique is useful for electrochemical processing of metal and alloy surfaces by utilizing faradaic reactions like electrodeposition and electrodissolution. A theoretical framework is presented in chapter 4 to facilitate quantitative analysis of experimental data (current transients) obtained in this approach. A typical application of this analysis is demonstrated for an experimental system involving electrochemical removal of copper surface layers, a relatively new process for abrasive-free electrochemical mechanical planarization of copper lines used in the fabrication of integrated circuits. Voltage pulse modulated electrodissolution of Cu in the absence of mechanical polishing is activated in an acidic solution of oxalic acid and hydrogen peroxide. The current generated by each applied voltage step shows a sharp spike, followed by a double-exponential decay, and eventually attains the rectangular shape of the potential pulses. For the second system in chapter 5, open-circuit potential measurements, cyclic voltammetry and Fourier transform impedance spectroscopy have been used to study pH dependent surface reactions of Cu and Ta rotating disc electrodes (RDEs) in aqueous solutions of succinic acid (SA, a complexing agent), hydrogen peroxide (an oxidizer), and ammonium dodecyl sulfate (ADS, a corrosion inhibitor for Cu). The surface chemistries of these systems are relevant for the development of a single-slurry approach to chemical mechanical planarization (CMP) of Cu

On quantum mechanical phase-space wave functions

DEFF Research Database (Denmark)

Wlodarz, Joachim J.

1994-01-01

An approach to quantum mechanics based on the notion of a phase-space wave function is proposed within the Weyl-Wigner-Moyal representation. It is shown that the Schrodinger equation for the phase-space wave function is equivalent to the quantum Liouville equation for the Wigner distribution...... function. The relationship to the recent results by Torres-Vega and Frederick [J. Chem. Phys. 98, 3103 (1993)] is also discussed....

Applications of disorder-induced melting concept to critical-solute-accumulation processes

International Nuclear Information System (INIS)

Lam, N.Q.; Okamoto, P.R.; Heuer, J.K.

2001-01-01

A generalized version of the Lindemann melting criterion has recently been used to develop a unified thermodynamic description of disorder-induced amorphization and heat-induced melting. This concept of amorphization as a melting process is based on the fact that the melting temperature of a defective crystal driven far from equilibrium will decrease relative to that of its defect-free equilibrium state. The broader view of melting provides a new perspective of damage-accumulation processes such as radiation damage, ion implantation, ion beam mixing, plastic deformation, and fracture. For example, within this conceptual framework, disorder-induced amorphization is simply polymorphous melting of a critically disordered crystal at temperatures below the glass transition temperature. In the present communication, we discuss the application of the concept to two specific cases: amorphous phase formation during ion implantation and solute segregation-induced intergranular fracture

Swelling, mechanical and friction properties of PVA/PVP hydrogels after swelling in osmotic pressure solution.

Science.gov (United States)

Shi, Yan; Xiong, Dangsheng; Liu, Yuntong; Wang, Nan; Zhao, Xiaoduo

2016-08-01

The potential of polyvinyl alcohol/polyvinylpyrrolidone (PVA/PVP) hydrogels as articular cartilage replacements was in vitro evaluated by using a macromolecule-based solution to mimic the osmotic environment of cartilage tissue. The effects of osmotic pressure solution on the morphology, crystallinity, swelling, mechanical and friction properties of PVA/PVP hydrogels were investigated by swelling them in non-osmotic and osmotic pressure solutions. The results demonstrated that swelling ratio and equilibrium water content were greatly reduced by swelling in osmotic solution, and the swelling process was found to present pseudo-Fickian diffusion character. The crystallization degree of hydrogels after swelling in osmotic solution increased more significantly when it compared with that in non-osmotic solution. After swelling in osmotic solution for 28days, the compressive tangent modulus and storage modulus of hydrogels were significantly increased, and the low friction coefficient was reduced. However, after swelling in the non-osmotic solution, the compressive tangent modulus and friction coefficient of hydrogels were comparable with those of as-prepared hydrogels. The better material properties of hydrogels in vivo than in vitro evaluation demonstrated their potential application in cartilage replacement. Copyright © 2016 Elsevier B.V. All rights reserved.

Device for isolation of seed crystals during processing of solution

Science.gov (United States)

Montgomery, K.E.; Zaitseva, N.P.; Deyoreo, J.J.; Vital, R.L.

1999-05-18

A device is described for isolation of seed crystals during processing of solutions. The device enables a seed crystal to be introduced into the solution without exposing the solution to contaminants or to sources of drying and cooling. The device constitutes a seed protector which allows the seed to be present in the growth solution during filtration and overheating operations while at the same time preventing the seed from being dissolved by the under saturated solution. When the solution processing has been completed and the solution cooled to near the saturation point, the seed protector is opened, exposing the seed to the solution and allowing growth to begin. 3 figs.

Phases definition in marketing export process

Directory of Open Access Journals (Sweden)

Rajković Dragan

2004-01-01

Full Text Available The result of export marketing process depends on its five phases. The first phase-revision of export capacities, inner view on advantages and defects of company concerning export possibilities. The second phase-identification of export strategy market penetration. The forth phase-preparing for the marketing campaign (action. The fifth phase-carrying out the above mentioned activities. This study shows the structure and contents of the mentioned phases. At the end, export marketing analyzed DPV is given as the example.

Synthesis of Diopside by Solution Combustion Process Using Glycine Fuel

Science.gov (United States)

Sherikar, Baburao N.; Umarji, A. M.

Nano ceramic Diopside (CaMgSi2O6) powders are synthesized by Solution Combustion Process(SCS) using Calcium nitrate, Magnesium nitrate as oxidizer and glycine as fuel, fumed silica as silica source. Ammonium nitrate (AN) is used as extra oxidizer. Effect of AN on Diopside phase formation is investigated. The adiabatic flame temperatures are calculated theoretically for varying amount of AN according to thermodynamic concept and correlated with the observed flame temperatures. A “Multi channel thermocouple setup connected to computer interfaced Keithley multi voltmeter 2700” is used to monitor the thermal events during the process. An interpretation based on maximum combustion temperature and the amount of gases produced during reaction for various AN compositions has been proposed for the nature of combustion and its correlation with the characteristics of as synthesized powder. These powders are characterized by XRD, SEM showing that the powders are composed of polycrystalline oxides with crystallite size of 58nm to 74nm.

Impact of molecular solvophobicity vs. solvophilicity on device performances of dimeric perylene diimide based solution-processed non-fullerene organic solar cells.

Science.gov (United States)

Lu, Zhenhuan; Zhang, Xin; Zhan, Chuanlang; Jiang, Bo; Zhang, Xinliang; Chen, Lili; Yao, Jiannian

2013-07-21

Because of their outstanding molecular optoelectronic properties, perylene diimides (PDIs) are promising alternatives to the commonly used PCBM. However, the overly strong aggregation ability, poor solution-processability and compatibility of PDIs severely limit their photovoltaic applications. We turned to borrowing the amphiphile concept to improve these supramolecular properties. Practically, we fine-tuned the molecular solvophobicity with respect to the molecular solvophilicity, e.g. F(solvophob/solvophil), by changing the number of the weakly solvophobic 2-methoxyethoxyl (EG) groups in the bay-region of the thienyl-bridged dimeric PDI backbone, forming three PDI dimers of Bis-PDI-T (0 EG), Bis-PDI-T-EG (2 EG) and Bis-PDI-T-di-EG (4 EG) (Scheme 1). The photovoltaic properties using these dimers as the solution-processed non-fullerene electron-acceptor and P3HT as the electron-donor were investigated via the device configuration of ITO/PEDOT:PSS/P3HT:PDI dimer/Ca/Al. Bis-PDI-T exhibited overly strong aggregation ability and very poor solution-processability, which severely limited compatibility, giving a very poor power conversion efficiency (PCE) of 0.007%. When two EG groups were attached at the 1,1'-positions, the resulted Bis-PDI-T-EG showed dramatically reduced aggregation ability, improved solution-processability, compatibility and proper phase separation. Small sized phases (∼20 nm) dominated in the active layer and the best PCE was increased to 0.39%. When four solvophobic EG functions were introduced, affording Bis-PDI-T-di-EG with excellent supramolecular properties, particularly, the improvement of the phase separation with an increased phase size of 24 nm and the enhanced electron and hole mobilities, by 2-4 times, with respect to that of Bis-PDI-T-EG. The best PCE was further enhanced to 0.88%. After using 1-chloronaphthalene as the co-solvent of 1,2-dichlorobenzene to further improve the compatibility, the PCE was improved further up to 0.41% for

Properties of solutions of Bloch-type equations for the paraelectric phase of KDP

Energy Technology Data Exchange (ETDEWEB)

Glowacki, M; Paszkiewicz, T [Wroclaw Univ. (Poland). Inst. Fyziki Teoretycznej

1979-10-01

Exact solutions for two sets of Bloch-like equations describing the paraelectric phase of the model of KDP were studied. The general properties of both solutions are the same. However, in numerical calculations they differ significantly. A modification of the decay law connected with the soft mode frequency fluctuations is considered.

A novel Canadian solution for processing and disposal of mixed liquid wastes

International Nuclear Information System (INIS)

Suryanarayan, S.; Husain, A.; Husain, S.; Grey, M.; Elwood, C.; White, T.; Wigle, K.

2011-01-01

In 2009, Bruce Power contracted with Kinectrics for the disposal of its accumulated mixed liquid waste (MLW) inventory. The waste consists of solvent, PCB (Poly Chlorinated Biphenyls) and non-PCB contaminated oils and aqueous waste drums. The radioactivity in the wastes is principally due to cobalt-60, cesium-137 and tritium. Historically, MLW drums originating from Canadian utilities were shipped to a licensed US facility for destruction via incineration. This option is relatively expensive considering the significant logistics and destruction costs involved. In addition, restrictions now apply on importation of PCB containing wastes in to the US. Because of this, Kinectrics developed a wholly Canadian solution for the disposal of the MLW. Disposal of Bruce Power's MLW was conceived to be carried out in three phases. Phase 1: Develop an overall plan for disposal of the accumulated wastes, Phase 2: Dispose the PCB oil waste drums (highest priority), and Phase 3: Dispose all other waste drums. Phases 1 & 2 have been completed and Phase 3 is currently underway with 17 drums having been disposed so far. A description of the key activities undertaken to date are described in this paper. This work sets the stage for the future management of MLW based exclusively or largely on disposal within Canada. All key technical, regulatory and logistical issues pertaining to the receipt, handling, processing and shipment of the wastes were addressed. Equipment was installed for basic processing of the incoming wastes. Based on Pathways methodology, it was shown that the wastes can be shipped to unlicensed facilities within Canada without exceeding the 10 μSv per annum exposure to the critical individual. Despite this and for compliance with ALARA, wastes exceeding self-imposed threshold levels of radioactivity will be solidified and shipped for storage as radioactive waste. (author)

A novel Canadian solution for processing and disposal of mixed liquid wastes

Energy Technology Data Exchange (ETDEWEB)

Suryanarayan, S.; Husain, A. [Kinectrics Inc., Toronto, ON (Canada); Husain, S.; Grey, M. [Candesco, Toronto, ON (Canada); Elwood, C.; White, T.; Wigle, K. [Bruce Power, Tiverton, ON (Canada)

2011-07-01

In 2009, Bruce Power contracted with Kinectrics for the disposal of its accumulated mixed liquid waste (MLW) inventory. The waste consists of solvent, PCB (Poly Chlorinated Biphenyls) and non-PCB contaminated oils and aqueous waste drums. The radioactivity in the wastes is principally due to cobalt-60, cesium-137 and tritium. Historically, MLW drums originating from Canadian utilities were shipped to a licensed US facility for destruction via incineration. This option is relatively expensive considering the significant logistics and destruction costs involved. In addition, restrictions now apply on importation of PCB containing wastes in to the US. Because of this, Kinectrics developed a wholly Canadian solution for the disposal of the MLW. Disposal of Bruce Power's MLW was conceived to be carried out in three phases. Phase 1: Develop an overall plan for disposal of the accumulated wastes, Phase 2: Dispose the PCB oil waste drums (highest priority), and Phase 3: Dispose all other waste drums. Phases 1 & 2 have been completed and Phase 3 is currently underway with 17 drums having been disposed so far. A description of the key activities undertaken to date are described in this paper. This work sets the stage for the future management of MLW based exclusively or largely on disposal within Canada. All key technical, regulatory and logistical issues pertaining to the receipt, handling, processing and shipment of the wastes were addressed. Equipment was installed for basic processing of the incoming wastes. Based on Pathways methodology, it was shown that the wastes can be shipped to unlicensed facilities within Canada without exceeding the 10 μSv per annum exposure to the critical individual. Despite this and for compliance with ALARA, wastes exceeding self-imposed threshold levels of radioactivity will be solidified and shipped for storage as radioactive waste. (author)

PROCESS OF ELIMINATING HYDROGEN PEROXIDE IN SOLUTIONS CONTAINING PLUTONIUM VALUES

Science.gov (United States)

Barrick, J.G.; Fries, B.A.

1960-09-27

A procedure is given for peroxide precipitation processes for separating and recovering plutonium values contained in an aqueous solution. When plutonium peroxide is precipitated from an aqueous solution, the supernatant contains appreciable quantities of plutonium and peroxide. It is desirable to process this solution further to recover plutonium contained therein, but the presence of the peroxide introduces difficulties; residual hydrogen peroxide contained in the supernatant solution is eliminated by adding a nitrite or a sulfite to this solution.

Formation of soft magnetic high entropy amorphous alloys composites containing in situ solid solution phase

Science.gov (United States)

Wei, Ran; Sun, Huan; Chen, Chen; Tao, Juan; Li, Fushan

2018-03-01

Fe-Co-Ni-Si-B high entropy amorphous alloys composites (HEAACs), which containing high entropy solid solution phase in amorphous matrix, show good soft magnetic properties and bending ductility even in optimal annealed state, were successfully developed by melt spinning method. The crystallization phase of the HEAACs is solid solution phase with body centered cubic (BCC) structure instead of brittle intermetallic phase. In addition, the BCC phase can transformed into face centered cubic (FCC) phase with temperature rise. Accordingly, Fe-Co-Ni-Si-B high entropy alloys (HEAs) with FCC structure and a small amount of BCC phase was prepared by copper mold casting method. The HEAs exhibit high yield strength (about 1200 MPa) and good plastic strain (about 18%). Meanwhile, soft magnetic characteristics of the HEAs are largely reserved from HEAACs. This work provides a new strategy to overcome the annealing induced brittleness of amorphous alloys and design new advanced materials with excellent comprehensive properties.

The mechanism of vapor phase hydration of calcium oxide: implications for CO2 capture.

Science.gov (United States)

Kudłacz, Krzysztof; Rodriguez-Navarro, Carlos

2014-10-21

Lime-based sorbents are used for fuel- and flue-gas capture, thereby representing an economic and effective way to reduce CO2 emissions. Their use involves cyclic carbonation/calcination which results in a significant conversion reduction with increasing number of cycles. To reactivate spent CaO, vapor phase hydration is typically performed. However, little is known about the ultimate mechanism of such a hydration process. Here, we show that the vapor phase hydration of CaO formed after calcination of calcite (CaCO3) single crystals is a pseudomorphic, topotactic process, which progresses via an intermediate disordered phase prior to the final formation of oriented Ca(OH)2 nanocrystals. The strong structural control during this solid-state phase transition implies that the microstructural features of the CaO parent phase predetermine the final structural and physicochemical (reactivity and attrition) features of the product hydroxide. The higher molar volume of the product can create an impervious shell around unreacted CaO, thereby limiting the efficiency of the reactivation process. However, in the case of compact, sintered CaO structures, volume expansion cannot be accommodated in the reduced pore volume, and stress generation leads to pervasive cracking. This favors complete hydration but also detrimental attrition. Implications of these results in carbon capture and storage (CCS) are discussed.

A theory of phase separation in asphaltene-micellar solutions

Energy Technology Data Exchange (ETDEWEB)

Pacheco Sanchez, Juan H. [Instituto Mexicano del Petroleo, Mexico D.F. (Mexico)

2001-08-01

A theory of phase separation in micellar solutions of asphaltene in aromatic hydrocarbons was reported in this paper, based on both the approach of the phase behavior of amphiphile/water micelles, and the self-association of asphaltene in aromatic core. Several experimental techniques have been used by different investigators showing the existence of some kind of critical micellar concentration (CMC) on asphaltenes in aromatic solutions. So, at least asphaltene-monomer and asphaltene-micellar phases are experimentally demonstrated facts. These two phases are the main purpose in this report on a theoretical model. Some results show the temperature versus asphaltene concentration phase diagram. The phase diagram is examined against the limited critical micelle concentration data for asphaltenes-in-toluene systems. Such phase diagram is also qualitatively examined against an experimental demonstration of phase separation. The asphaltene-micelle growth depends on the parameter K responsible for the shape and size of it. At the same time, parameter K depends on both the number of asphaltene-monomer associated in the asphaltene-micelle, and the chemical potentials in the interior and in the periphery of the micelle. An expression for getting the number of asphaltene-monomers self-associated in the asphaltene-micelle was obtained. [Spanish] Se reporta una teoria de separacion de fases en soluciones micelares de asfalteno en hidrocarburos aromaticos, basada tanto en la conducta de fase de micelas formadas por anififilos en agua como en la autoasociacion de asfaltenos en nucleos aromaticos. Se han usado diversas tecnicas experimentales por diferentes investigadores que demuestran la existancia de algun tipo de concentracion micelar critica (CMC) de soluciones de asfaltenos en aromaticos. Entonces, al menos las fases de asfalteno-monomerico y de asfalteno-micelar son hechos experimentalmente demostrados. Esta dos fases son el principal proposito de este reporte en un modelo

Vanadium doped Sb2Te3 material with modified crystallization mechanism for phase-change memory application

International Nuclear Information System (INIS)

Ji, Xinglong; Zheng, Yonghui; Zhou, Wangyang; Wu, Liangcai; Cao, Liangliang; Zhu, Min; Rao, Feng; Song, Zhitang; Feng, Songlin

2015-01-01

In this paper, V 0.21 Sb 2 Te 3 (VST) has been proposed for phase-change memory applications. With vanadium incorporating, VST has better thermal stability than Sb 2 Te 3 and can maintain in amorphous phase at room temperature. Two resistance steps were observed in temperature dependent resistance measurements. By real-time observing the temperature dependent lattice structure evolution, VST presents as a homogenous phase throughout the whole thermal process. Combining Hall measurement and transmission electron microscopy results, we can ascribe the two resistance steps to the unique crystallization mechanism of VST material. Then, the amorphous thermal stability enhancement can also be rooted in the suppression of the fast growth crystallization mechanism. Furthermore, the applicability of VST is demonstrated by resistance-voltage measurement, and the phase transition of VST can be triggered by a 15 ns electric pulse. In addition, endurance up to 2.7×10 4 cycles makes VST a promising candidate for phase-change memory applications

Recent Advances of Solution-Processed Metal Oxide Thin-Film Transistors.

Science.gov (United States)

Xu, Wangying; Li, Hao; Xu, Jian-Bin; Wang, Lei

2018-03-06

Solution-processed metal oxide thin-film transistors (TFTs) are considered as one of the most promising transistor technologies for future large-area flexible electronics. This review surveys the recent advances in solution-based oxide TFTs, including n-type oxide semiconductors, oxide dielectrics and p-type oxide semiconductors. Firstly, we provide an introduction on oxide TFTs and the TFT configurations and operating principles. Secondly, we present the recent progress in solution-processed n-type transistors, with a special focus on low-temperature and large-area solution processed approaches as well as novel non-display applications. Thirdly, we give a detailed analysis of the state-of-the-art solution-processed oxide dielectrics for low-voltage electronics. Fourthly, we discuss the recent progress in solution-based p-type oxide semiconductors, which will enable the highly desirable future low-cost large-area complementary circuits. Finally, we draw the conclusions and outline the perspectives over the research field.

Study on Microstructure and Mechanical Properties of Al-Li Based Alloys Processed by Extrusion.

Science.gov (United States)

Kim, Yong-Ho; Yoo, Hyo-Sang; Jung, Chang-Gi; Son, Hyeon-Taek

2018-03-01

Aluminum and its alloys, due to their low density, high specific strength and high corrosion resistance amongst various structural materials, are used in a wide range of industrial applications for different aqueous solutions. In the present study, we studied effects of Ce addition on microstructure and mechanical properties of Al-2Li-1Cu-0.8Mg-0.1Zr alloys. The melt was held at 780 °C for 20 min and poured into a mold. And as-cast Al alloys were hot-extruded into a plate that was 4 mm in thickness with a reduction ratio of 14:1. The extruded plates were held at 540 °C for 4 hr in water quenching to solution treatment them. As-extruded Al-2Li-1Cu-0.8Mg-0.1Zr-xCe (x = 0.3, 0.6, 0.9 and 1.2 wt.%) alloys are composed of Al, AlLi, AlCuLi and Al11Ce3 phases. By increasing the Ce content from 0 to 1.2 wt.%, the Al11Ce3 phase is increased, after solution treatment the AlLi and AlCuLi phases are decreased. With increasing Ce addition from 0 to 1.2 wt.%, the average grain size of the as-extruded Al alloys were decreased slightly from 100.7, 113.74, 84.3, 74.7 and 61.7 μm and ultimate tensile strength was decreased slightly from 267.59, 264.92, 237.40, 220.93 and 207.83 MPa at room temperature. After solution treatment, ultimate tensile strength was measured with 205.13, 198.12, 195.50, 198.27 and 208.01 MPa at room temperature.

Supramolecular organization of organic phases for DIAMEX solvent extraction process; Organisation supramoleculaire des phases organiques de malonamides du procede d'extraction DIAMEX

Energy Technology Data Exchange (ETDEWEB)

Martinet, L

2005-04-15

In the frame of nuclear waste cycle, supramolecular organization of organic phases has been studied for DIAMEX solvent extraction process. A general methodology has been developed in order to determine surfactant properties of an extractant at high concentration. An illustration is given by a malonamide (DMDBTDMA) at 0.7 mol/L, in dodecane and contacted with water, at 23 deg C. The concentrations of monomers (0.3 mol/L) and aggregates (0.4 mol/L), c.m.c. (0.25 mol/L), aggregation number (4,4), aggregation constant (7.7) and finally aggregates interactions (U/kT = -1.6) are quantified. The method is based on simultaneous utilization of four experimental techniques (small X-ray and neutron scattering, vapour pressure osmometry and tensiometry) added to the model of Baxter. The structure of malonamide organic phase is depending on extractant concentration. (i) Below 0.2 mol/L, it is a quasi-molecular liquid fluid, extracting few amount of solutes. (ii) From 0.2 to 1 mol/L, it is a complex liquid fluid, containing small spherical aggregates of 5 extractant molecules in coexistence with monomers. This phase behaves like typical microemulsions with reverse micelles, through its stabilizing effect of penetrating oil and steric repulsion between extractants. (iii) Above 1 mol/L, the organic phase is able to extract huge amount of solutes. When HNO{sub 3} or Nd(NO{sub 3} ){sub 3} are extracted, a gel with a pseudo-lamellar structure is observed. With UO{sub 2} (NO{sub 3} ){sub 2} a solid crystal with a ratio DMDBTDMA/UO{sub 2} (NO{sub 3} ){sub 2} equal to 1/1 is characteristic of the organic phase. The 'third phase' due to attractive interactions between aggregates has exactly the same supramolecular structure than an 'unsplitted organic phase' of the same composition. Aggregates interactions are independent on the chemical affinity of the extractant for solutes. (author)

Fully solution-processing route toward highly transparent polymer solar cells.

Science.gov (United States)

Guo, Fei; Kubis, Peter; Stubhan, Tobias; Li, Ning; Baran, Derya; Przybilla, Thomas; Spiecker, Erdmann; Forberich, Karen; Brabec, Christoph J

2014-10-22

We report highly transparent polymer solar cells using metallic silver nanowires (AgNWs) as both the electron- and hole-collecting electrodes. The entire stack of the devices is processed from solution using a doctor blading technique. A thin layer of zinc oxide nanoparticles is introduced between photoactive layer and top AgNW electrode which plays decisive roles in device functionality: it serves as a mechanical foundation which allows the solution-deposition of top AgNWs, and more importantly it facilitates charge carriers extraction due to the better energy level alignment and the formation of ohmic contacts between the active layer/ZnO and ZnO/AgNWs. The resulting semitransparent polymer:fullerene solar cells showed a power conversion efficiency of 2.9%, which is 72% of the efficiency of an opaque reference device. Moreover, an average transmittance of 41% in the wavelength range of 400-800 nm is achieved, which is of particular interest for applications in transparent architectures.

Studies of the underlying mechanisms for optical nonlinearities of blue phase liquid crystals (Presentation Recording)

Science.gov (United States)

Chen, Chun-Wei; Khoo, Iam Choon; Zhao, Shuo; Lin, Tsung-Hsien; Ho, Tsung-Jui

2015-10-01

We have investigated the mechanisms responsible for nonlinear optical processes occurring in azobenzene-doped blue phase liquid crystals (BPLC), which exhibit two thermodynamically stable BPs: BPI and BPII. In coherent two wave-mixing experiments, a slow (minutes) and a fast (few milliseconds) side diffractions are observed. The underlying mechanisms were disclosed by monitoring the dynamics of grating formation and relaxation as well as by some supplementary experiments. We found the photothermal indexing and dye/LC intermolecular torque leading to lattice distortion to be the dominant mechanisms for the observed nonlinear response in BPLC. Moreover, the response time of the nonlinear optical process varied with operating phase. The rise time of the thermal indexing process was in good agreement with our findings on the temperature dependence of BP refractive index: τ(ISO) > τ(BPI) > τ(BPII). The relaxation time of the torque-induced lattice distortion was analogue to its electrostriction counterpart: τ'(BPI) > τ'(BPII). In a separate experiment, lattice swelling with selective reflection of direction changed from green to red was also observed. This was attributable to the isomerization-induced change in cholesteric pitch, which directly affects the lattice spacing. The phenomenon was confirmed by measuring the optical rotatory power of the BPLC.

CP-violating Majorana phases, lepton-conserving processes, and final state interactions

International Nuclear Information System (INIS)

Nieves, Jose F.; Pal, Palash B.

2003-01-01

The CP-violating phases associated with Majorana neutrinos can give rise to CP-violating effects even in processes that conserve total lepton number, such as μ→eee-bar, μe→ee, and others. After explaining the reasons that make this happen, we consider the calculation of the rates for a process of the form l a l b →l a l c and its conjugate l-bar a l-bar b →l-bar a l-bar c , where l a ,l b ,l c denote charged leptons of different flavors. In the context of the standard model with Majorana neutrinos, we show that the difference in the rates depends on such phases. Our calculations illustrate in detail the mechanics that operate behind the scene, and set the stage for carrying out the analogous, more complicated (as we explain) calculations for other processes such as μ→eee-bar and its conjugate

Phase-separation phenomena in solutions of poly(2,6-dimethyl-1,4 phenylene oxide). II. Differential scanning calorimetry of solutions in toluene

NARCIS (Netherlands)

Koenhen, D.M.; Smolders, C.A.

1977-01-01

The phase-separation phenomena observed in solutions of poly(2,6 dimethyl-1,4 phenylene oxide) in toluene have been investigated by differential scanning calorimetry. These measurements supplement the experimental evidence in favor of the concept that the phase transitions observed are

Formation of nano quasicrystalline and crystalline phases by mechanical alloying

International Nuclear Information System (INIS)

Shamah, A.M.; Ibrahim, S.; Hanna, F.F.

2011-01-01

Research highlights: → Mechanical alloying (MA) is an important method to investigate the formation of nano sized quasicrystalline phases in Al 86 Cr 14 , Al 84 Fe 16 and Al 62.5 Cu 25 Fe 12.5 compounds. The second part of the present work is an attempt to examine the possibility of formation of the i-phase of the Al 62.5 Cu 25 Fe 12.5 , which lies in the region of the perfect i-phase in the ternary phase diagram, by rapid solidification method. To perform the obtained quasi phase mechanical alloying and heat treatment at the rapid solidified sample were done. - Abstract: In the present work, the formation of nano quasicrystalline icosahedral phase in Al 86 Cr 14 , Al 84 Fe 16 and Al 62.5 Cu 25 Fe 12.5 alloys has been investigated by mechanical alloying. Mixtures of quasicrystalline and related crystalline phases have been observed under various milling conditions. The X-ray diffraction, differential thermal analysis and electrical resistivity techniques have been used for characterization and physical property measurements. The particle size was calculated by X-ray profile using Williamson-Hall plot method and it was found to be 25-50 nm size.

Synthesis mechanism of heterovalent Sn2O3 nanosheets in oxidation annealing process

International Nuclear Information System (INIS)

Zhao Jun-Hua; Wu Guo-Qiang; Yang Xu-Feng; Tan Rui-Qin; Yang Ye; Xu Wei; Li Jia; Shen Wen-Feng; Song Wei-Jie

2015-01-01

Heterovalent Sn 2 O 3 nanosheets were fabricated via an oxidation annealing process and the formation mechanism was investigated. The temperature required to complete the phase transformation from Sn 3 O 4 to Sn 2 O 3 was considered. Two contrasting experiments showed that both oxygen and heating were not necessary conditions for the phase transition. Sn 2 O 3 was formed under an argon protective atmosphere by annealing and could also be obtained at room temperature by exposing Sn 3 O 4 in atmosphere or dispersing in ethanol. The synthesis mechanism was proposed and discussed. This fundamental research is important for the technological applications of intermediate tin oxide materials. (paper)

Assessment of metal sorption mechanisms by aquatic macrophytes using PIXE analysis

Energy Technology Data Exchange (ETDEWEB)

Módenes, A.N., E-mail: anmodenes@yahoo.com.br [Department of Chemical Engineering-Postgraduate Program, West Parana State University, Campus of Toledo, rua da Faculdade 645, Jd. La Salle, 85903-000 Toledo, PR (Brazil); Espinoza-Quiñones, F.R.; Santos, G.H.F.; Borba, C.E. [Department of Chemical Engineering-Postgraduate Program, West Parana State University, Campus of Toledo, rua da Faculdade 645, Jd. La Salle, 85903-000 Toledo, PR (Brazil); Rizzutto, M.A. [Physics Institute, University of São Paulo, Rua do Matão s/n, Travessa R 187, 05508-900 São Paulo, SP (Brazil)

2013-10-15

Highlights: • Divalent metal ion removals by Egeria densa biosorbent. • Multielements concentrations in biosorbent samples by PIXE analysis. • Elements mass balance in liquid and solid phase before and after metal removals. • Assessment of the mechanisms involved in Cd{sup 2+} and Zn{sup 2+} removal by biosorbent. • Confirmation of the signature of ion exchange process in metal removal. -- Abstract: In this work, a study of the metal sorption mechanism by dead biomass has been performed. All batch metal biosorption experiments were performed using the aquatic macrophyte Egeria densa as biosorbent. Divalent cadmium and zinc solutions were used to assess the sorption mechanisms involved. Using a suitable equilibrium time of 2 h and a mixture of 300 mg biosorbent and 50 mL metal solution at pH 5, monocomponent sorption experiments were performed. In order to determine the residual amounts of metals in the aqueous solutions and the concentrations of removed metals in the dry biomass, Particle Induced X-ray Emission (PIXE) measurements in thin and thick target samples were carried out. Based on the strong experimental evidence from the mass balance among the major elements participating in the sorption processes, an ion exchange process was identified as the mechanism responsible for metal removal by the dry biomass.

The mechanical properties and microstructures of vanadium bearing high strength dual phase steels processed with continuous galvanizing line simulations

Science.gov (United States)

Gong, Yu

For galvanized or galvannealed steels to be commercially successful, they must exhibit several attributes: (i) easy and inexpensive processing in the hot mill, cold mill and on the coating line, (ii) high strength with good formability and spot weldability, and (iii) good corrosion resistance. At the beginning of this thesis, compositions with a common base but containing various additions of V or Nb with or without high N were designed and subjected to Gleeble simulations of different galvanizing(GI), galvannealing(GA) and supercooling processing. The results revealed the phase balance was strongly influenced by the different microalloying additions, while the strengths of each phase were somewhat less affected. Our research revealed that the amount of austenite formed during intercritical annealing can be strongly influenced by the annealing temperature and the pre-annealing conditions of the hot band (coiling temperature) and cold band (% cold reduction). In the late part of this thesis, the base composition was a low carbon steel which would exhibit good spot weldability. To this steel were added two levels of Cr and Mo for strengthening the ferrite and increasing the hardenability of intercritically formed austenite. Also, these steels were produced with and without the addition of vanadium in an effort to further increase the strength. Since earlier studies revealed a relationship between the nature of the starting cold rolled microstructure and the response to CGL processing, the variables of hot band coiling temperature and level of cold reduction prior to annealing were also studied. Finally, in an effort to increase strength and ductility of both the final sheet (general formability) and the sheared edges of cold punched holes (local formability), a new thermal path was developed that replaced the conventional GI ferrite-martensite microstructure with a new ferrite-martensite-tempered martensite and retained austenite microstructure. The new

Formation and mechanism of nanocrystalline AZ91 powders during HDDR processing

Energy Technology Data Exchange (ETDEWEB)

Liu, Yafen; Fan, Jianfeng, E-mail: fanjianfeng@tyut.edu.cn; Zhang, Hua; Zhang, Qiang; Gao, Jing; Dong, Hongbiao, E-mail: hd38@leicester.ac.uk; Xu, Bingshe

2017-03-15

Grain sizes of AZ91 alloy powders were markedly refined to about 15 nm from 100 to 160 μm by an optimized hydrogenation-disproportionation-desorption-recombination (HDDR) process. The effect of temperature, hydrogen pressure and processing time on phase and microstructure evolution of AZ91 alloy powders during HDDR process was investigated systematically by X-ray diffraction, optical microscopy, scanning electron microscopy and transmission electron microscopy, respectively. The optimal HDDR process for preparing nanocrystalline Mg alloy powders is hydriding at temperature of 350 °C under 4 MPa hydrogen pressure for 12 h and dehydriding at 350 °C for 3 h in vacuum. A modified unreacted core model was introduced to describe the mechanism of grain refinement of during HDDR process. - Highlights: • Grain size of the AZ91 alloy powders was significantly refined from 100 μm to 15 nm. • The optimal HDDR technology for nano Mg alloy powders is obtained. • A modified unreacted core model of grain refinement mechanism was proposed.

The effect of cation:anion ratio in solution on the mechanism of barite growth at constant supersaturation: Role of the desolvation process on the growth kinetics

Science.gov (United States)

Kowacz, M.; Putnis, C. V.; Putnis, A.

2007-11-01

The mechanism of barite growth has been investigated in a fluid cell of an Atomic Force Microscope by passing solutions of constant supersaturation ( Ω) but variable ion activity ratio ( r=a/a) over a barite substrate.The observed dependence of step-spreading velocity on solution stoichiometry can be explained by considering non-equivalent attachment frequency factors for the cation and anion. We show that the potential for two-dimensional nucleation changes under a constant thermodynamic driving force due to the kinetics of barium integration into the surface, and that the growth mode changes from preexisting step advancement to island spreading as the cation/anion activity ratio increases. Scanning electron microscopy studies of crystals grown in bulk solutions support our findings that matching the ion ratio in the fluid to that of the crystal lattice does not result in maximum growth and nucleation rates. Significantly more rapid rates correspond to solution stoichiometries where [Ba 2+] is in excess with respect to [ SO42-]. Experiments performed in dilute aqueous solutions of methanol show that even 0.02 molar fraction of organic cosolvent in the growth solution significantly accelerates step growth velocity and nucleation rates (while keeping Ω the same as in the reference solution in water). Our observations suggest that the effect of methanol on barite growth results first of all from reduction of the barrier that prevents the Ba 2+ from reaching the surface and corroborate the hypothesis that desolvation of the cation and of the surface is the rate limiting kinetic process for two-dimensional nucleation and for crystal growth.

K Basin Sludge Conditioning Process Testing Partitioning of PCBs in Dissolver Solution After Neutralization/Precipitation (Caustic Adjustment)

International Nuclear Information System (INIS)

Schmidt, A.J.; Thornton, B.M.; Hoppe, E.W.; Mong, G.M.; Silvers, K.L.; Slate, S.O.

1999-01-01

The purpose of the work described in this report was to gain a better understanding of how PCB congeners present in a simulated K Basin sludge dissolver solution will partition upon neutralization and precipitation (i.e., caustic adjustment). In a previous study (Mong et al. 1998),the entire series of sludge conditioning steps (acid dissolution, filtration, and caustic adjustment) were examined during integrated testing. In the work described here, the caustic adjustment step was isolated to examine the fate of PCBs in more detail within this processing step. For this testing, solutions of dissolver simulant (containing no solids) with a known initial concentration of PCB congeners were neutralized with caustic to generate a clarified supernatant and a settled sludge phase. PCBs were quantified in each phase (including the PCBs associated with the test vessel rinsates), and material balance information was collected

PHENOMENOLOGY AND MECHANISMS OF THE SOLUTION OF EXISTENTIAL INTRAPERSONAL CONFLICTS

Directory of Open Access Journals (Sweden)

Krasilnikov Igor Aleksandrovich

2013-05-01

Full Text Available In the article sights of founders of existential psychology at phenomenology and psychological mechanisms of intrapersonal conflicts are considered. It is underlined, that the basic internal conflict is connected with existential anxiety, human life-death. Experience of the existence in the modern social world often has tragical character for the person. The solution of existential intrapersonal conflicts is defined by how the person could realize in itself deep «Me» connected with feeling of finding of internal and external freedom, creative and spontaneity. It is emphasized, that freedom is the main quality of social human life, but the way to it demands from the person of the responsibility, courage and honesty. The authorship of own destiny, personal identity are a source of the solution of existential intrapersonal conflicts. Not each person is capable to keep authenticity in the life. Integrity «Me» cannot be restored, ignoring cultural mental-moral values. Purpose. To study phenomenology and psychological mechanisms of the solution of existential intrapersonal conflicts. Methodology. The qualitative theoretical analysis and synthesis of literary data. Results. In the article general concepts of leading scientists-psychologists of existential orientation to phenomenology and mechanisms of the solution of intrapersonal conflicts are presented. The significant attention is given R. Meya's to sights, as one of the main representatives of existential psychotherapy. Practical implications. Preparation of psychologists in the field of psychotherapeutic consultation.

Wave Phase-Sensitive Transformation of 3d-Straining of Mechanical Fields

Science.gov (United States)

Smirnov, I. N.; Speranskiy, A. A.

2015-11-01

It is the area of research of oscillatory processes in elastic mechanical systems. Technical result of innovation is creation of spectral set of multidimensional images which reflect time-correlated three-dimensional vector parameters of metrological, and\\or estimated, and\\or design parameters of oscillations in mechanical systems. Reconstructed images of different dimensionality integrated in various combinations depending on their objective function can be used as homeostatic profile or cybernetic image of oscillatory processes in mechanical systems for an objective estimation of current operational conditions in real time. The innovation can be widely used to enhance the efficiency of monitoring and research of oscillation processes in mechanical systems (objects) in construction, mechanical engineering, acoustics, etc. Concept method of vector vibrometry based on application of vector 3D phase- sensitive vibro-transducers permits unique evaluation of real stressed-strained states of power aggregates and loaded constructions and opens fundamental innovation opportunities: conduct of continuous (on-line regime) reliable monitoring of turboagregates of electrical machines, compressor installations, bases, supports, pipe-lines and other objects subjected to damaging effect of vibrations; control of operational safety of technical systems at all the stages of life cycle including design, test production, tuning, testing, operational use, repairs and resource enlargement; creation of vibro-diagnostic systems of authentic non-destructive control of anisotropic characteristics of materials resistance of power aggregates and loaded constructions under outer effects and operational flaws. The described technology is revolutionary, universal and common for all branches of engineering industry and construction building objects.