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Sample records for deposit faces dissolution

  1. Dissolution of quartz in aqueous basic solution, 106-236 C - Surface kinetics of 'perfect' crystallographic faces

    Science.gov (United States)

    Gratz, Andrew J.; Bird, Peter; Quiro, Glenn B.

    1990-01-01

    A highly accurate method, called the negative crystal method, for determining the rate of dissolution on specific crystallographic faces of crystals was developed, in which the dissolution rates of nominally perfect crystal faces are obtained by measuring the size of individual negative crystals during a sequence of dissolution steps. The method was applied to determine the apparent activation energy and rate constants for the dissolution of quartz in 0.01 M KOH solutions at temperatures from 106 to 236 C. Also investigated were the effects of hydroxyl activity and ionic strength. The apparent activation energies for the dissolution of the prism and of the rhomb were determined.

  2. Modeling and simulation of NiO dissolution and Ni deposition in molten carbonate fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Suk Woo; Choi, Hyung-Joon; Lim, Tae Hoon [Korea Institute of Science & Technology, Seoul (Korea, Republic of)] [and others

    1996-12-31

    Dissolution of NiO cathode into the electrolyte matrix is an important phenomena limiting the lifetime of molten carbonate fuel cell (MCFC). The dissolved nickel diffuses into the matrix and is reduced by dissolved hydrogen leading to the formation of metallic nickel films in the pores of the matrix. The growth of Ni films in the electrolyte matrix during the continuous cell operation results eventually in shorting between cathode and anode. Various mathematical and empirical models have been developed to describe the NiO dissolution and Ni deposition processes, and these models have some success in estimating the lifetime of MCFC by correlating the amount of Ni deposited in the matrix with shorting time. Since the exact mechanism of Ni deposition was not well understood, deposition reaction was assumed to be very fast in most of the models and the Ni deposition region was limited around a point in the matrix. In fact, formation of Ni films takes place in a rather broad region in the matrix, the location and thickness of the film depending on operating conditions as well as matrix properties. In this study, we assumed simple reaction kinetics for Ni deposition and developed a mathematical model to get the distribution of nickel in the matrix.

  3. Experimental Study on Gold Dissolution from Hosting Minerals of the Hadamengou Gold Deposit and the Implications

    Institute of Scientific and Technical Information of China (English)

    LI Qiangzhi; YAN Fengzeng; WANG Xinhu

    2008-01-01

    The Hadamengou gold deposit is located in western part of the northern margin of the NorthChina craton. It is a hydrothermai deposit related to alkaline magmatism. Dissolution of Au, Fe frompyrite and iron oxide (including magnetite and hematite) individual minerals in the three main types ofore shows: in iron oxides (magnetite and hematite), Au and Fe were dissolved simultaneously and theirsolubilities are positively correlated, which means Au is mainly chemical-bonded (lattice gold) and/orcolloidal-adsorbed in iron oxides; while in pyrite, on the contrary, Au dissolution obviously lags behindFe and the solubility of Au shows negative relationship with that of Fe, which indicates Au is mainlyhosted as grains of elemental gold (or native gold) within pyrite. Previous studies revealed that theHadamengou gold deposit is characterized by intensive K-feldspathization and holds high content ofiron oxides occasionally replaced by sulfides, which was caused by oxidizing K-enriched alkaline fluidsunder a stretching geodynamic setting. These geological features, together with the high Au-content iniron oxides, comparable with that of the Olympic Dam deposit in South Australia, suggest that thisdeposit is the first example of iron oxide-type gold deposits in China.

  4. Electrochemical Deposition and Dissolution of Aluminum in NaAlCl4 Melts

    DEFF Research Database (Denmark)

    Li, Qingfeng; Hjuler, H.A.; Berg, Rolf W.

    1990-01-01

    Effects of the additives MnCl2, sulfide, and their combined influence on aluminum deposition and dissolution inNaAlCl4 saturated with NaCl have been studied by polarization measurements, galvanostatic deposition, and current reversalchronopotentiometry (CRC). The solubility of MnCl2 was found...... to be 0.086 ± 0.006 m/o in the melt at 175°C. Aluminum-manganesealloys can be deposited in NaAlCl4 saturated with both NaCl and MnCl2, resulting in a slight increase incathodic overpotentials. The codeposition of the binary alloys at current densities below 4 mA/cm2 gave rise to formationof deposits so...

  5. Lab-Scale Study of the Calcium Carbonate Dissolution and Deposition by Marine Cyanobacterium Phormidium subcapitatum

    Science.gov (United States)

    Karakis, S. G.; Dragoeva, E. G.; Lavrenyuk, T. I.; Rogochiy, A.; Gerasimenko, L. M.; McKay, D. S.; Brown, I. I.

    2006-01-01

    Suggestions that calcification in marine organisms changes in response to global variations in seawater chemistry continue to be advanced (Wilkinson, 1979; Degens et al. 1985; Kazmierczak et al. 1986; R. Riding 1992). However, the effect of [Na+] on calcification in marine cyanobacteria has not been discussed in detail although [Na+] fluctuations reflect both temperature and sea-level fluctuations. The goal of these lab-scale studies therefore was to study the effect of environmental pH and [Na+] on CaCO3 deposition and dissolution by marine cyanobacterium Phormidium subcapitatum. Marine cyanobacterium P. subcapitatum has been cultivated in ASN-III medium. [Ca2+] fluctuations were monitored with Ca(2+) probe. Na(+) concentrations were determined by the initial solution chemistry. It was found that the balance between CaCO3 dissolution and precipitation induced by P. subcapitatum grown in neutral ASN III medium is very close to zero. No CaCO3 precipitation induced by cyanobacterial growth occurred. Growth of P. subcapitatum in alkaline ASN III medium, however, was accompanied by significant oscillations in free Ca(2+) concentration within a Na(+) concentration range of 50-400 mM. Calcium carbonate precipitation occurred during the log phase of P. subcapitatum growth while carbonate dissolution was typical for the stationary phase of P. subcapitatum growth. The highest CaCO3 deposition was observed in the range of Na(+) concentrations between 200-400 mM. Alkaline pH also induced the clamping of P. subcapitatum filaments, which appeared to have a strong affinity to envelop particles of chemically deposited CaCO3 followed by enlargement of those particles size. EDS analysis revealed the presence of Mg-rich carbonate (or magnesium calcite) in the solution containing 10-100 mM Na(+); calcite in the solution containing 200 mM Na(+); and aragonite in the solution containing with 400 mM Na(+). Typical present-day seawater contains xxmM Na(+). Early (Archean) seawater was

  6. Power Deposition on Tokamak Plasma-Facing Components

    CERN Document Server

    Arter, Wayne; Fishpool, Geoff

    2014-01-01

    The SMARDDA software library is used to model plasma interaction with complex engineered surfaces. A simple flux-tube model of power deposition necessitates the following of magnetic fieldlines until they meet geometry taken from a CAD (Computer Aided Design) database. Application is made to 1) models of ITER tokamak limiter geometry and 2) MASTU tokamak divertor designs, illustrating the accuracy and effectiveness of SMARDDA, even in the presence of significant nonaxisymmetric ripple field. SMARDDA's ability to exchange data with CAD databases and its speed of execution also give it the potential for use directly in the design of tokamak plasma facing components.

  7. Modeling the Evolution of the Fracture Permeability in Granite due to Free-face Dissolution and Pressure Solution

    Science.gov (United States)

    Lu, R.; Watanabe, N.; Shao, H.; Kolditz, O.

    2015-12-01

    This paper focuses on the evolution of the fracture permeability due to water-granite long-term interactions when deionized water flows through the fracture surface. Laboratory-scale batch experiments have been conducted by Yasuhara et al (2011), wherein artificial fractures are subject to a mechanical confining pressure, variable differential hydraulic pressures and different applied temperatures. The aqueous geochemical system involved in the chemical weathering of granite is investigated in the first place which is a mixture of several kinetic reactions corresponding to mineral dissolution and a series of equilibrium reactions corresponding to potential derivatives in the aqueous solution. As fracture surfaces are in contact under confining stress, mineral dissolution rates may be different at hydrostatically stressed open pore and at asperity contacts under non-hydrostatic stress. Especially at asperity contacts, intergranular pressure solution may accelerate mineral dissolution rates whose driving force is represented as the chemical potential difference between a stressed contact and a hydrostatically stressed open pore (Taron and Elsworth (2010)). To better understand dominant mechanisms in the system, a reactive transport model including both the free-face reactions and the pressure solution is developed in the open-source simulator OpenGeoSys. Fracture aperture is updated as a result of the mass removal from the open-pore walls and the contacting asperities. The study presents impacts of mineral composition and their spatial distribution on the permeability evolution. ReferencesYasuhara, H., Kinoshita, N., Ohfuji, H., Lee, D.S., Nakashima, S., and Kishida, K. (2011), Temporal alteration of fracture permeability in granite under hydrothermal conditions and its interpretation by coupled chemo-mechanical model. Applied Geochemistry 26: 2074-2088. Taron, J., and Elsworth, D. (2010). Constraints on compaction rate and equilibrium in the pressure solution creep

  8. Simulation on dissolute and dust dispersion in comprehensive mechanized heading face with forced-exhaust ventilation

    Institute of Scientific and Technical Information of China (English)

    NIE Wen; CHENG Wei-min; HAN Li; ZHOU Sheng-ju; YU Yan-bin; ZHAO Shan-shan

    2011-01-01

    According to the characteristics of comprehensive mechanized heading face,established the mathematical model of single-phase air flow with k-e two equations model,and have established k-e-(O)-kp mathematic model to solve two-phase flow of gas and particles in dust space with eulefian-eulerian method and eulerian-lagrangian method.Numerical solution of gas-particle two-phase flow was put forward based on collocated grid SIMPLE algorithm.Moreover,numerical simulation of dust concentration in fully mechanized caving face was carried out by using Fluent software.Finally,when in forced-exhaust ventilation circumstance,drawer type fan drum have less dust absorption,and most of dust spread to the other site; the dust concentration is inversely proportional to the distance from tunneling head,and the dust concentration has already diffused to decrease below 102 mg/m3 at the position ofx=12 m.Dust are more focused on relative side(in the range about y from 0 to 2 meter) of roadway space of press-ventilated fan drum,especially between tunneling place and drawer type fan drum; the roadway with road header have a higher dust concentration.These conclusions provide reliable theory basis for the dust prevention in comprehensive mechanized heading face.

  9. Influence of Substrates on the Electrochemical Deposition and Dissolution of Aluminum in NaAlCl4 Melts

    DEFF Research Database (Denmark)

    Li, Qingfeng; Hjuler, Hans Aage; Berg, Rolf W.

    1991-01-01

    The deposition and dissolution of aluminum in NaAlCl4 melts saturated with NaCl have been investigated by voltammetryand potentiometry for different electrode materials at 175°C. The tungsten and glassy carbon electrodes are shownto be electrochemically inert in the melts, whereas copper is elect......The deposition and dissolution of aluminum in NaAlCl4 melts saturated with NaCl have been investigated by voltammetryand potentiometry for different electrode materials at 175°C. The tungsten and glassy carbon electrodes are shownto be electrochemically inert in the melts, whereas copper...... and the coulombic charges used for glassy carbon electrodes, mainly because of poor adhesion of the deposits tothe substrate. The reversibility is noticeably affected by the magnitude of deposition current density for the tungsten electrodes,while it remains high on the nickel electrode under all conditions...... investigated. Nickel and, to some extent,tungsten electrodes proved to be appropriate as working anodes in the Al/NaCl-AlCl3/Ni battery system....

  10. The effect of antimony presence in anodic copper on kinetics and mechanism of anodic dissolution and cathodic deposition of copper

    Directory of Open Access Journals (Sweden)

    Stanković Z.D.

    2008-01-01

    Full Text Available The influence of the presence of Sb atoms, as foreign metal atoms in anode copper, on kinetics, and, on the mechanism of anodic dissolution and cathodic deposition of copper in acidic sulfate solution has been investigated. The galvanostatic single-pulse method has been used. Results indicate that presence of Sb atoms in anode copper increase the exchange current density as determined from the Tafel analysis of the electrode reaction. It is attributed to the increase of the crystal lattice parameter determined from XRD analysis of the electrode material.

  11. Atmospheric dissolved iron deposition to the global oceans: effects of oxalate-promoted Fe dissolution, photochemical redox cycling, and dust mineralogy

    OpenAIRE

    Johnson, M. S.; Meskhidze, N.

    2013-01-01

    Mineral dust deposition is suggested to be a significant atmospheric supply pathway of bioavailable iron (Fe) to Fe-depleted surface oceans. In this study, mineral dust and dissolved Fe (Fed) deposition rates are predicted for March 2009 to February 2010 using the 3-D chemical transport model GEOS-Chem implemented with a comprehensive dust-Fe dissolution scheme. The model simulates Fed production during the atmospheric transport of mineral dust taking into account inorganic and organic (oxala...

  12. Atmospheric dissolved iron deposition to the global oceans: effects of oxalate-promoted Fe dissolution, photochemical redox cycling, and dust mineralogy

    OpenAIRE

    Johnson, M. S.; Meskhidze, N.

    2013-01-01

    Mineral dust deposition is suggested to be a significant atmospheric supply pathway of bioavailable iron (Fe) to Fe-depleted surface oceans. In this study, mineral dust and dissolved Fe (Fed) deposition rates are predicted for March 2009 to February 2010 using the 3-D chemical transport model GEOS-Chem implemented with a comprehensive dust-Fe dissolution scheme. The model simulates Fed production during the atmospheric transport of mineral dust, taking into account inorganic...

  13. Crystal Growth and Dissolution of Methylammonium Lead Iodide Perovskite in Sequential Deposition: Correlation between Morphology Evolution and Photovoltaic Performance.

    Science.gov (United States)

    Hsieh, Tsung-Yu; Huang, Chi-Kai; Su, Tzu-Sen; Hong, Cheng-You; Wei, Tzu-Chien

    2017-03-01

    Crystal morphology and structure are important for improving the organic-inorganic lead halide perovskite semiconductor property in optoelectronic, electronic, and photovoltaic devices. In particular, crystal growth and dissolution are two major phenomena in determining the morphology of methylammonium lead iodide perovskite in the sequential deposition method for fabricating a perovskite solar cell. In this report, the effect of immersion time in the second step, i.e., methlyammonium iodide immersion in the morphological, structural, optical, and photovoltaic evolution, is extensively investigated. Supported by experimental evidence, a five-staged, time-dependent evolution of the morphology of methylammonium lead iodide perovskite crystals is established and is well connected to the photovoltaic performance. This result is beneficial for engineering optimal time for methylammonium iodide immersion and converging the solar cell performance in the sequential deposition route. Meanwhile, our result suggests that large, well-faceted methylammonium lead iodide perovskite single crystal may be incubated by solution process. This offers a low cost route for synthesizing perovskite single crystal.

  14. The effect of bi presence as impurities in anodic copper on kinetics and mechanism of anodic dissolution and cathodic deposition of copper

    Directory of Open Access Journals (Sweden)

    Stanković Zvonimir D.

    2010-01-01

    Full Text Available The influence of Bi, as foreign metal atoms in anode copper, on kinetics and mechanism of anodic dissolution and cathodic deposition of copper in acidic sulfate solution was investigated using the galvanostatic single-pulse method. Results indicate that presence of Bi atoms in anode copper increases the exchange current density, as determined from the Tafel analysis of the electrode reaction, which is attributed to the increase of the crystal lattice parameter determined from XRD analysis of the electrode material.

  15. Atmospheric dissolved iron deposition to the global oceans: effects of oxalate-promoted Fe dissolution, photochemical redox cycling, and dust mineralogy

    Directory of Open Access Journals (Sweden)

    M. S. Johnson

    2013-08-01

    Full Text Available Mineral dust deposition is suggested to be a significant atmospheric supply pathway of bioavailable iron (Fe to Fe-depleted surface oceans. In this study, mineral dust and dissolved Fe (Fed deposition rates are predicted for March 2009 to February 2010 using the 3-D chemical transport model GEOS-Chem implemented with a comprehensive dust-Fe dissolution scheme. The model simulates Fed production during the atmospheric transport of mineral dust, taking into account inorganic and organic (oxalate-promoted Fe dissolution processes, photochemical redox cycling between ferric (Fe(III and ferrous (Fe(II forms of Fe, dissolution of three different Fe-containing minerals (hematite, goethite, and aluminosilicates, and detailed mineralogy of wind-blown dust from the major desert regions. Our calculations suggest that during the year-long simulation ~0.26 Tg (1 Tg = 1012 g of Fed was deposited to global oceanic regions. Compared to simulations only taking into account proton-promoted Fe dissolution, the addition of oxalate and Fe(II/Fe(III redox cycling to the dust-Fe mobilization scheme increased total annual model-predicted Fed deposition to global oceanic regions by ~75%. The implementation of Fe(II/Fe(III photochemical redox cycling in the model also allows for the distinction between different oxidation states of deposited Fed. Our calculations suggest that during the daytime, large fractions of Fed deposited to the global oceans is likely to be in Fe(II form, while nocturnal fluxes of Fed are largely in Fe(III form. Model sensitivity simulations suggest Fed fluxes to the oceans can range from ~50% reduction to ~150% increase associated with the uncertainty in Fe-containing minerals commonly found in dust particles. This study indicates that Fed deposition to the oceans is controlled by total dust-Fe mass concentrations, mineralogy, the surface area of dust particles, atmospheric chemical composition, cloud processing, and meteorological parameters and

  16. Atmospheric dissolved iron deposition to the global oceans: effects of oxalate-promoted Fe dissolution, photochemical redox cycling, and dust mineralogy

    Directory of Open Access Journals (Sweden)

    M. S. Johnson

    2013-03-01

    Full Text Available Mineral dust deposition is suggested to be a significant atmospheric supply pathway of bioavailable iron (Fe to Fe-depleted surface oceans. In this study, mineral dust and dissolved Fe (Fed deposition rates are predicted for March 2009 to February 2010 using the 3-D chemical transport model GEOS-Chem implemented with a comprehensive dust-Fe dissolution scheme. The model simulates Fed production during the atmospheric transport of mineral dust taking into account inorganic and organic (oxalate-promoted Fe dissolution processes, photochemical redox cycling between ferric (Fe(III and ferrous (Fe(II forms of Fe, dissolution of three different Fe-containing minerals (hematite, goethite, and aluminosilicates, and detailed mineralogy of wind-blown dust from the major desert regions. Our calculations suggest that during the yearlong simulation ~ 0.26 Tg (1 Tg = 1012 g of Fed was deposited to global oceanic regions. Compared to simulations only taking into account proton-promoted Fe dissolution, the addition of oxalate to the dust-Fe mobilization scheme increased total annual model-predicted Fed deposition to global oceanic regions by ~ 75%. The implementation of Fe(II/Fe(III photochemical redox cycling in the model allows for the distinction between different oxidation states of deposited Fed. Our calculations suggest that during the daytime, large fractions of Fed deposited to the global oceans is likely to be in Fe(II form, while nocturnal fluxes of Fed are largely in Fe(III form. Model simulations also show that atmospheric fluxes of Fed can be strongly influenced by the mineralogy of Fe-containing compounds. This study indicates that Fed deposition to the oceans is controlled by total dust-Fe mass concentrations, mineralogy, the surface area of dust particles, atmospheric chemical composition, cloud processing, and meteorological parameters and exhibits complex and spatiotemporally variable patterns. Our study suggests that the explicit model

  17. Characterization of laser-irradiated co-deposited layers on plasma facing components from a tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Gasior, P.; Badziak, J.; Czarnecka, A.; Parys, P.; Wolowski, J.; Rosinski, M. [Andrzej Soltan Inst. for Nuclear Studies, Otwock-Swierk (Poland); Rubel, Marek [Royal Inst. of Technology, Stockholm (Sweden). Alfven Laboratory; Philipps, V. [Forschungszentrum Juelich (Germany). Inst. fuer Plasmaphysik

    2006-04-15

    An experimental setup and ion diagnostic method for laser-induced fuel removal and decomposition of co-deposited layers on plasma facing components from tokamaks are described. Nd:YAG 3.5 ns pulse laser with a repetition rate of 10 Hz and single-pulse energy of up to 0.8 J at 1.06 {mu}m has been used for irradiation of a graphite limiter tile from the TEXTOR tokamak. Comparative studies have been performed for a pure graphite plate as a reference target. Energy of emitted ions has been measured using a time-of-flight method. Early results show that laser pulses efficiently ablate the co-deposit removing both fuel species and heavy components such as Si, Ni, Cr, Fe and W present in the layers. Surface topography of the irradiated targets is also presented.

  18. Energy deposition and thermal effects of runaway electrons in ITER-FEAT plasma facing components

    Energy Technology Data Exchange (ETDEWEB)

    Maddaluno, G. E-mail: maddaluno@frascati.enea.it; Maruccia, G.; Merola, M.; Rollet, S

    2003-03-01

    The profile of energy deposited by runaway electrons (RAEs) of 10 or 50 MeV in International Thermonuclear Experimental Reactor-Fusion Energy Advanced Tokamak (ITER-FEAT) plasma facing components (PFCs) and the subsequent temperature pattern have been calculated by using the Monte Carlo code FLUKA and the finite element heat conduction code ANSYS. The RAE energy deposition density was assumed to be 50 MJ/m{sup 2} and both 10 and 100 ms deposition times were considered. Five different configurations of PFCs were investigated: primary first wall armoured with Be, with and without protecting CFC poloidal limiters, both port limiter first wall options (Be flat tile and CFC monoblock), divertor baffle first wall, armoured with W. The analysis has outlined that for all the configurations but one (port limiter with Be flat tile) the heat sink and the cooling tube beneath the armour are well protected for both RAE energies and for both energy deposition times. On the other hand large melting (W, Be) or sublimation (C) of the surface layer occurs, eventually affecting the PFCs lifetime.

  19. Characterization of reactive flow-induced evolution of carbonate rocks using digital core analysis- part 1: Assessment of pore-scale mineral dissolution and deposition.

    Science.gov (United States)

    Qajar, Jafar; Arns, Christoph H

    2016-09-01

    The application of X-ray micro-computed tomography (μ-CT) for quantitatively characterizing reactive-flow induced pore structure evolution including local particle detachment, displacement and deposition in carbonate rocks is investigated. In the studies conducted in this field of research, the experimental procedure has involved alternating steps of imaging and ex-situ core sample alteration. Practically, it is impossible to return the sample, with micron precision, to the same position and orientation. Furthermore, successive images of a sample in pre- and post-alteration states are usually taken at different conditions such as different scales, resolutions and signal-to-noise ratios. These conditions accompanying with subresolution features in the images make voxel-by-voxel comparisons of successive images problematic. In this paper, we first address the respective challenges in voxel-wise interpretation of successive images of carbonate rocks subject to reactive flow. Reactive coreflood in two carbonate cores with different rock types are considered. For the first rock, we used the experimental and imaging results published by Qajar et al. (2013) which showed a quasi-uniform dissolution regime. A similar reactive core flood was conducted in the second rock which resulted in wormhole-like dissolution regime. We particularly examine the major image processing operations such as transformation of images to the same grey-scale, noise filtering and segmentation thresholding and propose quantitative methods to evaluate the effectiveness of these operations in voxel-wise analysis of successive images of a sample. In the second part, we generalize the methodology based on the three-phase segmentation of normalized images, microporosity assignment and 2D histogram of image intensities to estimate grey-scale changes of individual image voxels for a general case where the greyscale images are segmented into arbitrary number of phases. The results show that local (voxel

  20. Anodic dissolution of gold in a solution of 1,3-diaminopropane with the formation of a cathodic deposit and a colloidal solution of Au

    Science.gov (United States)

    Vedenyapina, M. D.; Ubushieva, G. Ts.; Kuznetsov, V. V.; Makhova, N. N.; Vedenyapin, A. A.

    2016-11-01

    The corrosion of a Au anode in a solution of 1,3-diaminopropane (DAP) is studied by means of gravimetry. It is found that the products of corrosion of Au electrode in galvanostatic conditions are reduced on a Pt cathode with the formation of either an electrolytic Au deposit or a colloidal solution of metallic Au, depending on the current strength. The kinetics of the dissolution of Au in the presence of DAP is investigated. The formation of a complex of Au with DAP is observed, and a structure for it is proposed.

  1. Characterization of reactive flow-induced evolution of carbonate rocks using digital core analysis- part 1: Assessment of pore-scale mineral dissolution and deposition

    Science.gov (United States)

    Qajar, Jafar; Arns, Christoph H.

    2016-09-01

    The application of X-ray micro-computed tomography (μ-CT) for quantitatively characterizing reactive-flow induced pore structure evolution including local particle detachment, displacement and deposition in carbonate rocks is investigated. In the studies conducted in this field of research, the experimental procedure has involved alternating steps of imaging and ex-situ core sample alteration. Practically, it is impossible to return the sample, with micron precision, to the same position and orientation. Furthermore, successive images of a sample in pre- and post-alteration states are usually taken at different conditions such as different scales, resolutions and signal-to-noise ratios. These conditions accompanying with subresolution features in the images make voxel-by-voxel comparisons of successive images problematic. In this paper, we first address the respective challenges in voxel-wise interpretation of successive images of carbonate rocks subject to reactive flow. Reactive coreflood in two carbonate cores with different rock types are considered. For the first rock, we used the experimental and imaging results published by Qajar et al. (2013) which showed a quasi-uniform dissolution regime. A similar reactive core flood was conducted in the second rock which resulted in wormhole-like dissolution regime. We particularly examine the major image processing operations such as transformation of images to the same grey-scale, noise filtering and segmentation thresholding and propose quantitative methods to evaluate the effectiveness of these operations in voxel-wise analysis of successive images of a sample. In the second part, we generalize the methodology based on the three-phase segmentation of normalized images, microporosity assignment and 2D histogram of image intensities to estimate grey-scale changes of individual image voxels for a general case where the greyscale images are segmented into arbitrary number of phases. The results show that local (voxel

  2. High performance ZnO:Al films deposited on PET substrates using facing target sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Tingting [Solar Film Laboratory, School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China); Dong, Guobo, E-mail: wavedong@buaa.edu.cn [Solar Film Laboratory, School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China); Gao, Fangyuan; Xiao, Yu [Solar Film Laboratory, School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China); Chen, Qiang [Key Laboratory of Micro-nano Measurement-Manipulation and Physics (Ministry of Education), School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China); Diao, Xungang [Solar Film Laboratory, School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China)

    2013-10-01

    ZnO:Al (ZAO) thin films have been deposited on flexible PET substrates using a plasma damage-free facing target sputtering system at room temperature. The structure, surface morphology, electrical and optical properties were investigated as a function of working power. All the samples have a highly preferred orientation of the c-axis perpendicular to the PET substrate and have a high quality surface. With increased working power, the carrier concentration changes slightly, the mobility increases at the beginning and decreases after it reaches a maximum value, in line with electrical conductivity. The figure of merit has been significantly improved with increasing of the working power. Under the optimized condition, the lowest resistivity of 1.3 × 10{sup −3} Ω cm with a sheet resistance of 29 Ω/□ and the relative visible transmittance above 93% in the visible region were obtained.

  3. Endotoxin deposits on the inner surfaces of closed-face cassettes during bioaerosol sampling: a field investigation at composting facilities.

    Science.gov (United States)

    Duquenne, Philippe; Simon, Xavier; Demange, Valérie; Harper, Martin; Wild, Pascal

    2015-05-01

    A set of 270 bioaerosol samples was taken from 15 composting facilities using polystyrene closed-face filter cassettes (CFCs). The objective was to measure the quantity of endotoxin deposits on the inner surfaces of the cassettes (sometimes referred to as 'wall deposits'). The results show that endotoxins are deposited on the inner surfaces of the CFCs through sampling and/or handling of samples. The quantity of endotoxins measured on inner surfaces range between 0.05 (the limit of detection of the method) and 3100 endotoxin units per cassette. The deposits can represent a large and variable percentage of the endotoxins sampled. More than a third of the samples presented a percentage of inner surface deposits >40% of the total quantity of endotoxins collected (filter + inner surfaces). Omitting these inner surface deposits in the analytical process lead to measurement errors relative to sampling all particles entering the CFC sampler, corresponding to a developing consensus on matching the inhalable particulate sampling convention. The result would be underestimated exposures and could affect the decision as to whether or not a result is acceptable in comparison to airborne concentration limits defined in terms of the inhalability convention. The results of this study suggest including the endotoxins deposited on the inner surfaces of CFCs during analysis. Further researches are necessary to investigate endotoxin deposits on the inner cassette surfaces in other working sectors.

  4. Simulation of damage to tokamaks plasma facing components during intense abnormal power deposition

    Energy Technology Data Exchange (ETDEWEB)

    Genco, F., E-mail: fgenco@purdue.edu; Hassanein, A., E-mail: hassanein@purdue.edu

    2014-04-15

    Highlights: • HEIGHTS-PIC a new technique based on particle in cell method to study disruptions events, ELMS and VDE is benchmarked in this paper with the use of the MK-200 experiments. • Disruptions simulations results for erosion and erosion rate are proposed showing good agreement with published experimental available data for such conditions. • Results are also compared with other published results produced by FOREV1/FOREV2 computer package and the original HEIGHTS computer package. • Accuracy of the simulations results is proposed with specific aim to address the use of number of super particles adopted versus computational time. - Abstract: Intense power deposition on plasma facing components (PFC) is expected in tokamaks during loss of confinement events such as disruptions, vertical displacement events (VDE), runaway electrons (RE), or during normal operating conditions such as edge-localized modes (ELM). These highly energetic events are damaging enough to hinder long term operation and may not be easily mitigated without loss of structural or functional performance of the PFC. Surface erosion, melted/ablated-vaporized material splashing, and material transport into the bulk plasma are reliability-threatening for the machine and system performance. A novel particle-in-cell (PIC) technique has been developed and integrated into the existing HEIGHTS package in order to obtain a global view of the plasma evolution upon energy impingement. This newly developed PIC technique is benchmarked against plasma gun experimental data, the original HEIGHTS computer package, and laser experiments. Benchmarking results are shown in this paper for various relevant reactor and experimental devices. The evolution of the plasma vapor cloud is followed temporally and results are explained and commented as a function of the computational time needed and the accuracy of the calculation.

  5. Particle deposition on face-up flat plates in parallel airflow under the combined influences of thermophoresis and electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Handol; Yook, Sejin; Han, Seogyoung [Hanyang University, Seoul (Korea, Republic of)

    2012-10-15

    The deposition velocity is used to assess the degree of particulate contamination of wafers or photomasks. A numerical model was developed to predict the deposition velocity under the combined influences of thermophoresis and electrophoresis. The deposition velocity onto a face-up flat plate in parallel airflow was simulated by varying the temperature difference between the plate's surface and ambient air or by changing the strength of the electric field established above the plate. Both attraction and repulsion by thermophoresis or electrophoresis were considered. When the plate's surface was colder than ambient air, the surface of the face-up plate could be at risk of contamination by charged particles even with a repulsive applied electric force. When the temperature of the plate's surface was higher than the ambient temperature, the degree of particulate contamination on the surface of the face-up plate could be remarkably reduced in the presence of an electric field. The effect of repulsive thermophoresis, however, is expected to be reduced for very fine particles of high electric mobility or for micrometer-sized particles with large gravitational settling speed when the charged particles are influenced by an attractive electric force.

  6. Hyperinsulinemia and ectopic fat deposition develop in the face of hyperadiponectinemia in young obese rats

    Science.gov (United States)

    The role of reduced adiponenctin signaling in childhood obesity is unclear. Weanling male Sprague-Dawley rats were overfed a high fat diet via total enteral nutrition. Excessive caloric intake led to increased weight and fat mass; dyslipidemia; ectopic fat deposition; and hyperinsulinemia (P less th...

  7. On the re-dissolution of subsurface hydrothermal deposits at 9°50'N East Pacific Rise: Implications from geochemical studies of high- and low-temperature fluids

    Science.gov (United States)

    McDermott, J. M.; von Damm, K. L.

    2008-12-01

    Hydrothermal fluids circulated through mid-oceanic ridges provide the necessary chemical energy for biological reactions in the thriving deep biosphere (1). In order to refine hydrothermal flux estimates and determine the implications for macro- and microbiological communities, the processes controlling chemical composition of hydrothermal fluids must first be better understood. Low-temperature hydrothermal fluids, generated when high-temperature fluids mix with seawater during their ascent to the seafloor, have long been considered to be simple dilutions of high-temperature fluids with ambient seawater in the upper oceanic crust (2). However, the degree to which fluids undergo compositional changes due to further reaction in the subsurface prior to their expulsion at the seafloor has not been quantified. Potential processes that alter fluid chemistry may include the re-dissolution of previously precipitated minerals such as anhydrite and metal sulfides. One implication of these and possibly other undocumented mineral reactions is that the hydrothermal flux component of elemental budgets, specifically Ca, Sr, SO4, Fe, Mn, Cu and Zn, must be reinterpreted since these elements transit through the system via temporary sinks. Furthermore, these reactive processes influence trace metal concentrations in low-temperature fluids, thereby affecting the diversity and distribution of macro- and microbiological communities living on or within the seafloor at hydrothermal areas. The Ridge2000 Integrated Study Site at 9°50'N EPR contains an area in which two high-temperature vents (Ty and Io) formed from a low-temperature site (BM82), which remained active, thereby providing a unique opportunity to investigate the simple dilution model. Preliminary time series chemical data for Ty and Io spanning April 1991 through December 2007 support the hypothesis of re-dissolution of metal sulfide deposits. The means of end member Fe and Mn for Ty (4650 μmol/kg in Fe, 1500 μmol/kg in Mn

  8. Photocatalytic Activity of Reactively Sputtered Titania Coatings Deposited Using a Full Face Erosion Magnetron

    OpenAIRE

    Farahani, Nick; Kelly, Peter,; West, Glen; Hill, Claire; Vishnyakov, Vladimir

    2013-01-01

    Titanium dioxide (titania) is widely used as a photocatalyst for its moderate band gap, high photoactivity, recyclability, nontoxicity, low cost and its significant chemical stability. The anatase phase of titania is known to show the highest photocatalytic activity, however, the presence of this phase alone is not sufficient for sustained activity. In this study TiO2 coatings were deposited onto glass substrates by mid-frequency pulsed magnetron sputtering from metallic targets in reactive m...

  9. The influence of hydrogen- and cation-underpotential deposition on oxide-mediated Pt dissolution in proton-exchange membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seokkoo [Texas Materials Institute and Center for Electrochemistry, University of Texas at Austin, University Station, C2200 Austin, TX 78712-0292 (United States); Meyers, Jeremy P., E-mail: jeremypmeyers@austin.utexas.edu [Texas Materials Institute and Center for Electrochemistry, University of Texas at Austin, University Station, C2200 Austin, TX 78712-0292 (United States)

    2011-10-01

    Highlights: > Pt dissolution has a maximum value around E{sub L} = 0.5-0.6 V vs. RHE at CV, SW experiments. > The addition of Zn cation (5 mM) in acid solution increase Pt dissolution rate on the region E{sub L} < 0.2 V at E{sub H} = 1.6 V. > Pt dissolution is accelerated by convection flow at over 1.2 V vs. RHE. > The amount of Pt dissolution during Pt oxide reduction reaction is measured by RRDE experiment. - Abstract: In order to fully understand the influence of a lower potential limit on platinum dissolution and the likely mechanism for mass and surface-area loss under potential cycling conditions, the dissolution of a Pt catalyst in a N{sub 2}-saturated 0.5 M H{sub 2}SO{sub 4} solution was examined using an electrochemical quartz nanobalance (EQCN) flow cell, a rotating ring-disk electrode (RRDE) and inductively coupled plasma mass spectroscopy (ICP-MS). Due to the observation that cycling to a lower potential limit, which coincides with the hydrogen under-potential (H{sub UPD}) region, results in a decrease in the dissolution rate, cations capable of interfering with the hydrogen UPD process (Zn{sup 2+}, Li{sup +}, Na{sup +}, K{sup +}, and Cd{sup 2+}) were introduced to the solution. Larger rates of mass loss were observed in the presence of these cations during the cycling process in the UPD region, despite apparently negligible effects on the behavior with more positive lower potential limits or on oxide formation and stripping. It was found that the quantity of soluble Pt species produced during the electrochemical reduction of PtO{sub 2} was proportional to the charge associated with oxide stripping at the disk electrode during the RRDE experiment.

  10. Detailed View of Cliff-face in the North Polar Layered Deposits

    Science.gov (United States)

    1998-01-01

    On Earth, geologists use layers of rock to 'read' the history of our planet. Where rocks were initially formed as layers of sediment, the historic record of Earth is deciphered by knowing that older layers are found beneath the younger layers. Scientists investigating changes in Earth's climate over the past few million years also use this principle to examine cores of ice from Greenland and Antarctica. Layered rock and layered polar deposits on Mars may also preserve a comparable record of that planet's geologic and environmental history.The martian north and south polar regions are covered by large areas of layered deposits. Since their discovery in the early 1970's, these polar layered deposits have been cited as the best evidence that the martian climate experiences cyclic changes over time. It was proposed that detailed investigation of the polar layers (e.g., by landers and/or human beings) would reveal a climate record of Mars in much the same way that ice cores from Antarctica are used to study past climates on Earth. On January 3, 1999, NASA's Mars Polar Lander and Deep Space 2 Penetrators will launch on a journey to study the upper layers of these deposits in the martian southern hemisphere.Meanwhile, investigation of the north polar layered deposits has advanced significantly this year with the acquisition of MGS data. The Mars Orbiter Laser Altimeter acquired new topographic profiles over the north polar deposits in June and early July, 1998, and dozens of new high resolution images were taken by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) from mid-July to mid-September, 1998. When it was proposed to NASA in 1985, one of the original objectives of MOC was to determine whether the polar layered deposits--then thought to consist of 10 to 100 layers each between 10 and 100 meters (33 to 330 feet) thick--have more and thinner layers in them. The layers were proposed to have formed by slow accumulation of dust and ice--perhaps only 100

  11. Challenges, uncertainties and issues facing gas production from gas hydrate deposits

    Energy Technology Data Exchange (ETDEWEB)

    Moridis, G.J.; Collett, T.S.; Pooladi-Darvish, M.; Hancock, S.; Santamarina, C.; Boswell, R.; Kneafsey, T.; Rutqvist, J.; Kowalsky, M.; Reagan, M.T.; Sloan, E.D.; Sum, A.K.; Koh, C.

    2010-11-01

    The current paper complements the Moridis et al. (2009) review of the status of the effort toward commercial gas production from hydrates. We aim to describe the concept of the gas hydrate petroleum system, to discuss advances, requirement and suggested practices in gas hydrate (GH) prospecting and GH deposit characterization, and to review the associated technical, economic and environmental challenges and uncertainties, including: the accurate assessment of producible fractions of the GH resource, the development of methodologies for identifying suitable production targets, the sampling of hydrate-bearing sediments and sample analysis, the analysis and interpretation of geophysical surveys of GH reservoirs, well testing methods and interpretation of the results, geomechanical and reservoir/well stability concerns, well design, operation and installation, field operations and extending production beyond sand-dominated GH reservoirs, monitoring production and geomechanical stability, laboratory investigations, fundamental knowledge of hydrate behavior, the economics of commercial gas production from hydrates, and the associated environmental concerns.

  12. Dissolution vessel

    Energy Technology Data Exchange (ETDEWEB)

    Natsume, Tomohiro; Fujioka, Tsunaaki

    1998-05-22

    A basket for containing sheared fuel pieces of spent fuel assemblies in a dissolving vessel main body has many apertures for keeping the concentration of a dissolving liquid at the inner side and the outer side of the basket uniformly. Secured neutron absorbers such as boron stainless and hafnium are appended to one or both surfaces of the basket. Partitioning members are disposed in the basket, and the partitioning members are formed in a lattice-like shape. The partitioning members are also made of secured neutron absorbers such as boron stainless and hafnium. The inside dimension of each division (lattice distance) is determined to about 15cm. Then, it is no more necessary to add soluble neutron absorbers such as gadolinium nitrate to a dissolution solution such as nitric acid thereby enabling to reduce the amount of radioactive wastes. (I.N.)

  13. Influence of substrate temperature on growth of a-Si:H films by reactive facing target sputtering deposition

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Hydrogenated amorphous silicon(a-Si:H) films were deposited by reactive facing target sputtering(FTS) technique with a mixture of Ar and H2 reaction gas.Fourier transform infrared(FTIR) absorption,Raman scattering and ultraviolet-visible optical absorption are used to investigate the microstructure and optical properties of the deposited films.The decrease of the concentration of bonded hydrogen,especially that of(Si-H2)n with increasing substrate temperature(Ts),was observed in FTIR spectra,suggesting the atomic density increases and the concentration of microvoids decrease in a-Si:H films.The increase of both the short range order and the intermediate range order of amorphous network for a-Si:H films were verified by Raman scattering spectra,in which increasing Ts decreasing the band width of TO and the scattering intensity ratio ITA/ITO were obtained.All above results clarify the effect of increasing Ts on the microstructure amelioration for a-Si:H films.The reduction of disordered domains is correlated with the film growing process,where the increased surface diffusion mobility and etching of weak bonds is induced by increasing Ts.Furthermore,analysis of optical absorption indicates that the films with a lower optical band gap and a narrower band edge can be obtained by this FTS technique.

  14. Dissolution processes. [224 references

    Energy Technology Data Exchange (ETDEWEB)

    Silver, G.L.

    1976-10-22

    This review contains more than 100 observations and 224 references on the dissolution phenomenon. The dissolution processes are grouped into three categories: methods of aqueous attack, fusion methods, and miscellaneous observations on phenomena related to dissolution problems. (DLC)

  15. Selective dissolution in binary alloys

    Science.gov (United States)

    McCall, Carol Rene

    Corrosion is an important issue in the design of engineering alloys. De-alloying is an aspect of alloy corrosion related to the selective dissolution of one or more of the components in an alloy. The work reported herein focuses on the topic of de-alloying specific to single-phase binary noble metal alloy systems. The alloy systems investigated were gold-silver and gold-copper. The onset of a bulk selective dissolution process is typically marked by a critical potential whereby the more reactive component in the alloy begins dissolving from the bulk, leading to the formation of a bi-continuous solid-void morphology. The critical potential was investigated for the entire composition range of gold-silver alloys. The results presented herein include the formulation of an expression for critical potential as a function of both alloy and electrolyte composition. Results of the first investigation of underpotential deposition (UPD) on alloys are also presented herein. These results were implemented as an analytical tool to provide quantitative measurements of the surface evolution of gold during de-alloying. The region below the critical potential was investigated in terms of the compositional evolution of the alloy surface. Below the critical potential, there is a competition between the dissolution of the more reactive alloying constituent (either silver or copper) and surface diffusion of gold that serves to cover dissolution sites and prevent bulk dissolution. By holding the potential at a prescribed value below the critical potential, a time-dependent gold enrichment occurs on the alloy surface leading to passivation. A theoretical model was developed to predict the surface enrichment of gold based on the assumption of layer-by-layer dissolution of the more reactive alloy constituent. The UPD measurements were used to measure the time-dependent surface gold concentration and the results agreed with the predictions of the theoretical model.

  16. Dissolution Methods Database

    Data.gov (United States)

    U.S. Department of Health & Human Services — For a drug product that does not have a dissolution test method in the United States Pharmacopeia (USP), the FDA Dissolution Methods Database provides information on...

  17. Dissolution Methods Database

    Data.gov (United States)

    U.S. Department of Health & Human Services — For a drug product that does not have a dissolution test method in the United States Pharmacopeia (USP), the FDA Dissolution Methods Database provides information on...

  18. Study of laser-induced removal of co-deposits from tokamak plasma-facing components using ion diagnostics and optical spectroscopy

    Science.gov (United States)

    Wolowski, J.; Gasior, P.; Hoffman, J.; Kubkowska, M.; Rosinski, M.; Szymanski, Z.

    2010-10-01

    The paper presents studies of the application of ion diagnostics and optical spectroscopy for on-line measurement of the amount and characteristics of co-deposits from the laser-ablated surface of the plasma-facing components (e.g. graphite tiles). For removal of the co-deposit layer a repetitive Nd:YAG laser was used. Determination of the characteristics of ions emitted from the laser-illuminated targets was performed using ion collectors (on the basis of a time-of-flight method) and an optical spectrometer. The main ion stream parameters and spectral lines of deuterium and carbon or tungsten ions were measured depending on laser pulse parameters. The research proved that optical spectroscopy could be a convenient method for on-line observation of the co-deposited layer removal by means of laser ablation. In combination with the investigation of collected co-deposit dust, the performed study made it possible to state that laser-induced breakdown spectroscopy can be useful as a diagnostic method for the ablative co-deposited layer removal and the wall conditioning. The properties of modified surfaces of samples and collected dust (evaporated co-deposit) were determined using different measuring methods.

  19. Laser-induced removal of co-deposits from graphitic plasma-facing components: Characterization of irradiated surfaces and dust particles

    Science.gov (United States)

    Gąsior, P.; Irrek, F.; Petersson, P.; Penkalla, H. J.; Rubel, M.; Schweer, B.; Sundelin, P.; Wessel, E.; Linke, J.; Philipps, V.; Emmoth, B.; Wolowski, J.; Hirai, T.

    2009-06-01

    Laser-induced fuel desorption and ablation of co-deposited layers on limiter plates from the TEXTOR tokamak have been studied. Gas phase composition was monitored in situ, whereas the ex situ studies have been focused on the examination of irradiated surfaces and broad analysis of dust generated by ablation of co-deposits. The size of the dust grains is in the range of few nanometers to hundreds of micrometers. These are fuel-rich dust particles, as determined by nuclear reaction analysis. The presence of deuterium in dust indicates that not all fuel species are transferred to the gas phase during irradiation. This also suggests that photonic removal of fuel and the ablation of co-deposit from plasma-facing components may lead to the redistribution of fuel-containing dust to surrounding areas.

  20. Accelerated dissolution of iron oxides in ice

    Directory of Open Access Journals (Sweden)

    D. Jeong

    2012-08-01

    Full Text Available Iron dissolution from mineral dusts and soil particles is vital as a source of bioavailable iron in various environmental media. In this work, the dissolution of iron oxide particles trapped in ice was investigated as a~new pathway of iron supply. The dissolution experiments were carried out in the absence and presence of various organic complexing ligands under dark condition. In acidic pH conditions (pH 2, 3, and 4, the dissolution of iron oxides was greatly enhanced in the ice phase compared to that in water. The dissolved iron was mainly in the ferric form, which indicates that the dissolution is not a reductive process. The extent of dissolved iron was greatly affected by the kind of organic complexing ligands and the type of iron oxides. The iron dissolution was most pronounced with high surface area iron oxides and in the presence of strong iron binding ligands. The enhanced dissolution of iron oxides in ice is mainly ascribed to the "freeze concentration effect", which concentrates iron oxide particles, organic ligands, and protons in the liquid-like ice grain boundary region and accelerates the dissolution of iron oxides. The ice-enhanced dissolution effect gradually decreased when decreasing the freezing temperature from −10 °C to −196 °C, which implies that the presence and formation of the liquid-like ice grain boundary region play a critical role. The proposed phenomenon of enhanced dissolution of iron oxides in ice may provide a new pathway of bioavailable iron production. The frozen atmospheric ice with iron-containing dust particles in the upper atmosphere thaws upon descending and may provide bioavailable iron upon deposition onto the ocean surface.

  1. Accelerated dissolution of iron oxides in ice

    Directory of Open Access Journals (Sweden)

    D. Jeong

    2012-11-01

    Full Text Available Iron dissolution from mineral dusts and soil particles is vital as a source of bioavailable iron in various environmental media. In this work, the dissolution of iron oxide particles trapped in ice was investigated as a new pathway of iron supply. The dissolution experiments were carried out in the absence and presence of various organic complexing ligands under dark condition. In acidic pH conditions (pH 2, 3, and 4, the dissolution of iron oxides was greatly enhanced in the ice phase compared to that in water. The dissolved iron was mainly in the ferric form, which indicates that the dissolution is not a reductive process. The extent of dissolved iron was greatly affected by the kind of organic complexing ligands and the surface area of iron oxides. The iron dissolution was most pronounced with high surface area iron oxides and in the presence of strong iron binding ligands. The enhanced dissolution of iron oxides in ice is mainly ascribed to the "freeze concentration effect", which concentrates iron oxide particles, organic ligands, and protons in the liquid like ice grain boundary region and accelerates the dissolution of iron oxides. The ice-enhanced dissolution effect gradually decreased when decreasing the freezing temperature from −10 to −196 °C, which implies that the presence and formation of the liquid-like ice grain boundary region play a critical role. The proposed phenomenon of enhanced dissolution of iron oxides in ice may provide a new pathway of bioavailable iron production. The frozen atmospheric ice with iron-containing dust particles in the upper atmosphere thaws upon descending and may provide bioavailable iron upon deposition onto the ocean surface.

  2. AFM Study of Calcite Growth and Dissolution on the (104) Face%原子力显微镜法研究方解石(104)面的生长及溶解

    Institute of Scientific and Technical Information of China (English)

    吴聪孟; 王小强; 赵康; 曹美文; 徐海; 吕建仁

    2011-01-01

    研究生物矿化过程及生物矿物的形成机制具有重要的科学意义,这方面的研究不仅有助于我们认识自然,而且还可以指导体外仿生合成具有分级结构的功能性复合材料.原子力显微镜(atomic force microscope,AFM)是微米、纳米尺度上实时观测矿物成核或生长的强有力工具.本文综述了原子力显微镜法研究方解石(104)面生长及溶解的最新进展,重点论述了有机添加剂对(104)面生长和溶解的影响,讨论了添加剂分子与方解石晶面间的作用方式和机制,为理解生物矿物的形成机理提供了新的启示.已有的研究表明,有机添加剂可通过与方解石(104)面的位点专一性作用改变晶体微粒从溶液相进入晶体相的能垒、台阶边缘自由能及(104)表面活性位的数目,从而改变台阶的生长动力学,以致影响晶体的整体形貌.最后,本文对今后方解石生物矿化的研究重点进行了展望.%Living organisms have evolved ability to produce biominerals or composites with exquisite structures and unique functionalities. Such a process is usually termed as biomineralization. Due to its high relevance to the fabrication of advanced materials, biomineralization has attracted tremendous interest in the past years. A comprehensive understanding of the biomineralization process and the underlying mechanism enables the biomimetic synthesis of functional materials with finely mediated structures. AFM is a powerful tool for in situ following the formation of biominerals at the micrometer and nanometer scale, particularly observing the crystal nucleation and growth. This paper reviews the recent advances in the AFM studies of calcite, focusing on the effects of organic additives on the growth and dissolution of the calcite (104) face. These organic additives include ethanol,carboxylic acids, amino acids, peptides, proteins and saccharides. Several proposed mechanistic interactions between organic additives and

  3. Union Dissolution and Migration

    OpenAIRE

    Cooke, Thomas; Mulder, Clara H.; Thomas, Michael

    2016-01-01

    BACKGROUND While there is a limited body of research regarding residential mobility and migration following union dissolution, there is a particular dearth of studies that go into detail about the factors that shape how union dissolution may result in long-distance migration. OBJECTIVE This research isolates and identifies the processes that influence inter-state migration in the period immediately following the dissolution of a marital union. METHODS Multilevel logit models of the probabilit...

  4. Surface band bending and band alignment of plasma enhanced atomic layer deposited dielectrics on Ga- and N-face gallium nitride

    Science.gov (United States)

    Yang, Jialing; Eller, Brianna S.; Nemanich, Robert J.

    2014-09-01

    The effects of surface pretreatment, dielectric growth, and post deposition annealing on interface electronic structure and polarization charge compensation of Ga- and N-face bulk GaN were investigated. The cleaning process consisted of an ex-situ wet chemical NH4OH treatment and an in-situ elevated temperature NH3 plasma process to remove carbon contamination, reduce oxygen coverage, and potentially passivate N-vacancy related defects. After the cleaning process, carbon contamination decreased below the x-ray photoemission spectroscopy detection limit, and the oxygen coverage stabilized at ˜1 monolayer on both Ga- and N-face GaN. In addition, Ga- and N-face GaN had an upward band bending of 0.8 ± 0.1 eV and 0.6 ± 0.1 eV, respectively, which suggested the net charge of the surface states and polarization bound charge was similar on Ga- and N-face GaN. Furthermore, three dielectrics (HfO2, Al2O3, and SiO2) were prepared by plasma-enhanced atomic layer deposition on Ga- or N-face GaN and annealed in N2 ambient to investigate the effect of the polarization charge on the interface electronic structure and band offsets. The respective valence band offsets of HfO2, Al2O3, and SiO2 with respect to Ga- and N-face GaN were 1.4 ± 0.1, 2.0 ± 0.1, and 3.2 ± 0.1 eV, regardless of dielectric thickness. The corresponding conduction band offsets were 1.0 ± 0.1, 1.3 ± 0.1, and 2.3 ± 0.1 eV, respectively. Experimental band offset results were consistent with theoretical calculations based on the charge neutrality level model. The trend of band offsets for dielectric/GaN interfaces was related to the band gap and/or the electronic part of the dielectric constant. The effect of polarization charge on band offset was apparently screened by the dielectric-GaN interface states.

  5. Dissolution of Globular Clusters

    OpenAIRE

    Baumgardt, Holger

    2006-01-01

    Globular clusters are among the oldest objects in galaxies, and understanding the details of their formation and evolution can bring valuable insight into the early history of galaxies. This review summarises the current knowledge about the dissolution of star clusters and discusses the implications of star cluster dissolution for the evolution of the mass function of star cluster systems in galaxies.

  6. Moving and Union Dissolution

    Science.gov (United States)

    BOYLE, PAUL J.; KULU, HILL; COOKE, THOMAS; GAYLE, VERNON; MULDER, CLARAH.

    2008-01-01

    This paper examines the effect of migration and residential mobility on union dissolution among married and cohabiting couples. Moving is a stressful life event, and a large, multidisciplinary literature has shown that family migration often benefits one partner (usually the man) more than the other. Even so, no study to date has examined the possible impact of within-nation geographical mobility on union dissolution. We base our longitudinal analysis on retrospective event-history data from Austria. Our results show that couples who move frequently have a significantly higher risk of union dissolution, and we suggest a variety of mechanisms that may explain this. PMID:18390300

  7. Dissolution Power and Redistribution

    OpenAIRE

    Becher, Michael

    2015-01-01

    While democracies vary in whether they allow their chief executives to dissolve parliament and call an early election, recent theories of the economic consequences of executive-legislative institutions in comparative politics pay little attention to dissolution power. I develop a model to analyze how chief executives' ability to dissolve the legislature influences the stability and level of redistribution. It shows that dissolution power critically alters the ability of partisan chief executi...

  8. Moving and Union Dissolution

    OpenAIRE

    Boyle, P.J.; Kulu, H.; Cooke, T.; Gayle, V.; Mulder, C.H.

    2008-01-01

    This paper examines the effect of migration and residential mobility on union dissolution among married and cohabiting couples. Moving is a stressful life event, and a large, multidisciplinary literature has shown that family migration often benefits one partner (usually the man) more than the other. Even so, no study to date has examined the possible impact of within-nation geographical mobility on union dissolution. We base our longitudinal analysis on retrospective event-history data from ...

  9. Marital Dissolution in Japan

    OpenAIRE

    James M. Raymo; Bumpass, Larry L.; Miho Iwasawa

    2004-01-01

    Very little is known about recent trends in divorce in Japan. In this paper, we use Japanese vital statistics and census data to describe trends in the experience of marital dissolution across the life course, and to examine change over time in educational differentials in divorce. Cumulative probabilities of marital dissolution have increased rapidly across successive marriage cohorts over the past twenty years, and synthetic period estimates suggest that roughly one-third of Japanese marria...

  10. Response of plasma facing components in Tokamaks due to intense energy deposition using Particle-In-Cell (PIC) methods

    Science.gov (United States)

    Genco, Filippo

    Damage to plasma-facing components (PFC) due to various plasma instabilities is still a major concern for the successful development of fusion energy and represents a significant research obstacle in the community. It is of great importance to fully understand the behavior and lifetime expectancy of PFC under both low energy cycles during normal events and highly energetic events as disruptions, Edge-Localized Modes (ELM), Vertical Displacement Events (VDE), and Run-away electron (RE). The consequences of these high energetic dumps with energy fluxes ranging from 10 MJ/m2 up to 200 MJ/m 2 applied in very short periods (0.1 to 5 ms) can be catastrophic both for safety and economic reasons. Those phenomena can cause a) large temperature increase in the target material b) consequent melting, evaporation and erosion losses due to the extremely high heat fluxes c) possible structural damage and permanent degradation of the entire bulk material with probable burnout of the coolant tubes; d) plasma contamination, transport of target material into the chamber far from where it was originally picked. The modeling of off-normal events such as Disruptions and ELMs requires the simultaneous solution of three main problems along time: a) the heat transfer in the plasma facing component b) the interaction of the produced vapor from the surface with the incoming plasma particles c) the transport of the radiation produced in the vapor-plasma cloud. In addition the moving boundaries problem has to be considered and solved at the material surface. Considering the carbon divertor as target, the moving boundaries are two since for the given conditions, carbon doesn't melt: the plasma front and the moving eroded material surface. The current solution methods for this problem use finite differences and moving coordinates system based on the Crank-Nicholson method and Alternating Directions Implicit Method (ADI). Currently Particle-In-Cell (PIC) methods are widely used for solving

  11. AES/LEED/I(V) LEED investigation of ultrathin Pb and In layers deposited on Ni(001) and Ni(111) faces

    Energy Technology Data Exchange (ETDEWEB)

    Miskow, Katarzyna; Krupski, Aleksander [Institute of Experimental Physics, University of Wroclaw (Poland)

    2011-07-01

    Properties of ultrathin indium and lead layers deposited on Ni(001) and Ni(111) faces at temperature between T=150 K and T=950 K and coverage up to 6 ML have been studied by AES-t, LEED and I(V) LEED. For In/Ni(111), Frank-van den Merwe and Stranski-Krastanov type of growth is observed for temperature below and above 450 K, respectively. In case of In/Ni(001), below T<600 K it seems that Volumer-Weber or Simultaneous Multilayers type of growth plus Simultaneous Multilayers type of growth. For the adsorption of Pb on Ni(001) only Volumer-Weber type of growth is observed. Two different indium structures have been found for (001) and (111) faces of nickel. For In/Ni(001) the p(2 x 2) structure has been observed for temperature between 600 K and 950 K. At about 950 K, reconstruction of the p(2 x 2) structure to c(2 x 2) one takes place. In case of In/Ni(111) the p(2 x 2) structure has also been observed, but for temperature between 450 K and 850 K. At about 900 K reconstruction of the p(2 x 2) structure to the p(3 x 3)R30 one is observed. In case of Pb/Ni(001) only the c(2 x 2) structure has been observed. Indium makes surface alloy on both nickel crystal faces upon annealing while for lead, only desorption process is observed. The atomic structure and relaxation of the clean Ni(111) surface were investigated with the use of experimental I(V) LEED profiles and theoretical TensErLEED calculations.

  12. ZnO homoepitaxy on the O polar face of hydrothermal and melt-grown substrates by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, D.J. [Nanovation SARL, Orsay (France); Technical Univ. of Troyes (France); CNRS, Troyes (France); Hosseini Teherani, F. [Nanovation SARL, Orsay (France); Largeteau, A.; Demazeau, G. [ICMCB-CNRS, Bordeaux 1 University (Science and Technology), Pessac (France); Moisson, C.; Turover, D. [Novasic, Savoie Technolac, Arche Bat. 4, BP 267, Le Bourget du Lac (France); Nause, J. [Cermet Inc., Atlanta, GA (United States); Garry, G. [Thales Research, Domaine de Corbeville, Orsay (France); Kling, R.; Gruber, T. [Ulm University, Department of Semiconductor Physics, Ulm (Germany); Waag, A. [Braunschweig Technical University, Institute of Semiconductor Technology, Braunschweig (Germany); Jomard, F.; Galtier, P.; Lusson, A. [LPSC-CNRS, Meudon (France); Monteiro, T.; Soares, M.J.; Neves, A.; Carmo, M.C.; Peres, M. [University of Aveiro, Physics Department, Aveiro (Portugal); Lerondel, G.; Hubert, C. [Technical University of Troyes-CNRS (FRE2671), 12 rue Marie Curie, BP 2060, Troyes (France)

    2007-07-15

    2 cm diameter hydrothermal ZnO crystals were grown and then made into substrates using both mechanical and chemical-mechanical polishing (CMP). CMP polishing showed superior results with an (0002) {omega} scan full width half maximum (FWHM) of 67 arcsec and an root mean square (RMS) roughness of 2 Aa. In comparison, commercial melt-grown substrates exhibited broader X-ray diffraction (XRD) linewidths with evidence of sub-surface crystal damage due to polishing, including a downward shift of c-lattice parameter. Secondary ion mass spectroscopy revealed strong Li, Fe, Co, Al and Si contamination in the hydrothermal crystals as opposed to the melt-grown substrates, for which glow discharge mass spectroscopy studies had reported high levels of Pb, Fe, Cd and Si. Low temperature photoluminescence (PL) studies indicated that the hydrothermal crystal had high defect and/or impurity concentrations compared with the melt-grown substrate. The dominant bound exciton for the melt-grown substrate was indexed to Al. ZnO films were grown using pulsed laser deposition. The melt-grown substrates gave superior results with XRD (0002) {omega} and 2{theta}/{omega} WHM of 124 and 34 arcsec, respectively. Atomic force microscope measurements indicated a low RMS roughness (1.9 nm) as confirmed by fringes in the XRD 2{theta}/{omega} scan. It was suggested that the improvement in XRD response relative to the substrate might be due to ''healing'' of sub-surface polishing damage due to the elevated T{sub s} used for the growth. Indeed the c-lattice parameter for the homoepitaxial layer on the melt-grown substrate had become that which would be expected for strain-free ZnO. Furthermore, the stability of the PL peak positions relative to bulk ZnO, confirmed that the films appear practically strain free. (orig.)

  13. Interferometric study of the dolomite dissolution: a new conceptual model for mineral dissolution

    Science.gov (United States)

    Lttge, A.; Winkler, U.; Lasaga, A. C.

    2003-03-01

    The dissolution rate and mechanism of three different cleavage faces of a dolomite crystal from Navarra (near Pamplona), Spain, were studied in detail by vertical scanning interferometry techniques. A total of 37 different regions (each about 124 × 156 μm in size) on the three sample surfaces were monitored as a function of time during dissolution at 25°C and pH 3. Dissolution produced shallow etch pits with widths reaching 20 μm during 8 h of dissolution. Depth development as a function of time was remarkably similar for all etch pits on a given dolomite surface. On the basis of etch pit distribution and volume as a function of time, the calculated dissolution rate increases from near zero to 4 × 10 -11 mol cm -2 s -1 over 5 h. The time variation is different for each of the three cleavage surfaces studied. In addition, the absolute dissolution rates of different parts of the dolomite crystal surface can be computed by using a reference surface. The different surfaces yield an "average" rate of 1.08 × 10 -11 mol cm -2 s -1 with a standard deviation of 0.3 × 10 -11 mol cm -2 s -1 based on about 60 analyses. The mean absolute rate of the dolomite surface is about 10 times slower than the rate calculated from etch pit dissolution alone. On the other hand, earlier batch rate data that used BET surface areas yield rates that are at least 30 to 60 times faster than our directly measured mean dissolution rate for the same pH and temperature. A conceptual model for mineral dissolution has been inferred from the surface topography obtained by the interferometry investigations. In this model, mineral dissolution is not dominated by etch pit formation itself but rather by extensive dissolution stepwaves that originate at the outskirts of the etch pits. These stepwaves control the overall dissolution as well as the dependence on temperature and saturation state.

  14. Dissolution development of valdecoxib tablets

    Directory of Open Access Journals (Sweden)

    Subramanian G

    2006-01-01

    Full Text Available Valdecoxib is a nonsteroidal antiinflammatory drug, and it is listed in class 2 of biopharmaceutic classification of drugs. Valdecoxib is a poorly water-soluble and highly permeable drug. In the present study a new dissolution medium was developed, as there is no official dissolution medium available in the literature. The composition of the dissolution medium was selected on the basis of solubility data at 37°. Solubility data revealed that addition of surfactant may be suitable as dissolution medium. The concentration of 0.6% w/v sodium lauryl sulphate in water could be a suitable dissolution medium. The discriminating power of the selected dissolution medium (0.6% sodium lauryl sulphate in water relative to the other dissolution mediums was evaluated. The selected dissolution medium was used for the evaluation of valdecoxib tablets.

  15. Be/W and W/Be bilayers deposited on Si substrates with hydrogenated Fe-Cr and Fe-Cr-Al interlayers for plasma facing components

    Science.gov (United States)

    Greculeasa, S. G.; Palade, P.; Schinteie, G.; Lungu, G. A.; Porosnicu, C.; Jepu, I.; Lungu, C. P.; Kuncser, V.

    2016-12-01

    Be/W and W/Be bilayers, of interest in regard to the specific behavior of plasma facing components (PFCs) were deposited on Si substrates by thermionic vacuum arc, with Fe, Fe-Cr and Fe-Cr-Al interlayers. The interlayers, with compositions approaching the one of the reduced activation steels used in supporting PFCs, were subsequently annealed in hydrogen atmosphere. The multilayers were characterized with respect to morphologic, structural, diffusional and atomic intermixing aspects via XRD, XRR, X-ray photoemission spectroscopy and Mössbauer spectroscopy. All as-prepared samples present partially amorphous structures. A main α-Fe phase is observed, as well as (superparamagnetic) secondary Fe oxides, metallic Fe with Si, Cr, W and Be neighbors, Be-rich Fe-Be and Fe-Si phases. High amounts of tungsten and tungsten oxides were also evidenced in the Fe layer. The strong atomic intermixing of W and Be layers was indirectly supported by the unusual densities of W and Be layers and 57Fe Mössbauer spectroscopy results.

  16. Percutaneous dissolution of renal calculi.

    Science.gov (United States)

    Dretler, S P; Pfister, R C

    1983-01-01

    The use of percutaneous nephrostomy catheters has allowed access to intrarenal urinary calculi for dissolution. Renacidin is the successful agent for dissolving struvite stones. THAM-E is the most effective agent for the intrarenal dissolution of cystine stone. Calcium oxalate stones are still resistant to dissolution techniques.

  17. Determinants of marriage dissolution

    Science.gov (United States)

    Rahim, Mohd Amirul Rafiq Abu; Shafie, Siti Aishah Mohd; Hadi, Az'lina Abdul; Razali, Nornadiah Mohd; Azid @ Maarof, Nur Niswah Naslina

    2015-10-01

    Nowadays, the number of divorce cases among Muslim couples is very worrisome whereby the total cases reported in 2013 increased by half of the total cases reported in the previous year. The questions on the true key factors of dissolution of marriage continue to arise. Thus, the objective of this study is to reveal the factors that contribute to the dissolution of marriage. A total of 181 cases and ten potential determinants were included in this study. The potential determinants considered were age at marriage of husband and wife, educational level of husband and wife, employment status of husband and wife, income of husband and wife, the number of children and the presence at a counseling session. Logistic regression analysis was used to analyze the data. The findings revealed that four determinants, namely the income of husband and wife, number of children and the presence at a counselling session were significant in predicting the likelihood of divorce among Muslim couples.

  18. Wet hydrate dissolution plant

    OpenAIRE

    Stanković Mirjana S.; Kovačević Branimir T.; Pezo Lato L.

    2003-01-01

    The IGPC Engineering Department designed basic projects for a wet hydrate dissolution plant, using technology developed in the IGPC laboratories. Several projects were completed: technological, machine, electrical, automation. On the basis of these projects, a production plant with capacity of 50,000 t/y was manufactured, at "Zeolite Mira", Mira (VE), Italy, in 1997, for increasing detergent zeolite production from 50,000 to 100,000 t/y. Several goals were realized by designing a wet hydrate ...

  19. Random effects in drug dissolution.

    Science.gov (United States)

    Cupera, Jakub; Lansky, Petr

    2010-11-20

    The deterministic models of dissolution are commonly used in pharmaceutical studies, however, experimental results point to stochastic nature of the dissolution processes. In this paper we present stochastic modifications of deterministic models using the concept of Wiener process. The models are given in form of stochastic differential equations and their properties are studied. Probability distributions of the dissolution data are derived for all the stochastic models. Variability of the dissolution data is discussed and sources of the random fluctuations are divided into two categories - the variability of the dissolution vessel environment and the measurement errors. Based on these considerations a function describing variability of the dissolution data at each time instant is proposed. Practical application of the stochastic approach based on experimental data is illustrated by finding maximum-likelihood estimation of model parameters and identification of noise sources and their levels in the system. Their influence on the estimates of the mean dissolution time is shown.

  20. Dissolution properties of calcined gangue

    Institute of Scientific and Technical Information of China (English)

    Huajian Li; Henghu Sun; Xuchu Tie; Xuejun Xiao

    2006-01-01

    To study the dissolution mechanism of gangue, dissolution characteristics of the gangue samples calcined at different temperatures in alkaline solutions and alkali metal silicate solutions with respect to Si and A1 ions were analyzed by identical coupled plasma optical emission spectroscopy (ICP). The results show that the extent of dissolution of A1 and Si varies with calcination temperature. It shows that the samples have a higher degree of dissolution in NaOH than in KOH medium. Si and A1 appear to have synchro-dissolution behavior in alkaline solution, which means that Si and A1 could dissolve from the mineral surface in certain linked forms. The result that a higher degree of dissolution exists in sodium silicate solution and a lower degree of dissolution exists in sodium-potassium silicate solution of A1 is proved by the 29Si NMR spectra and the mean connectivity degree of these alkali metal silicate solutions.

  1. 沙丘背风侧气流及其沉积类型与意义%Lee-face Airflow, Depositional Types and Its Significance

    Institute of Scientific and Technical Information of China (English)

    哈斯; 王贵勇; 董光荣

    2001-01-01

    deposits. Also, the resulting deposition would consist grainflow cross-strata, and direction of dune a dvance would be perpendicular to the lee face. In this case, the dip direction of cross bedding would be the same to the primary wind direction. In oblique flow condit ions, the deflected flow controlled the lee-slops and sands from stoss-slop not deposited but transported along the lee-slop. As a result, migrating wind rippl e or smaller dunes (in the case of dune lee-slop with enough size) were the only processes operating on the lee-slop except the narrow belt of upper slop near dune crest. The deposition resulting from such flow conditions would consist of cl imb ing ripple cross-lamina or compound cross strata with grainflow cross-strata s ep arated by second-order bounding surfaces. The dip direction of climbing ripple l amina is a function of underlying slops so that could not reflect the primary wi nd direction in most cases. The dip direction of the cross-strata resulting fro m superposed dunes on larger ones indicates only lee face secondary flow directio n and does not the primary wind direction. The dips of the second-order boundin g surface is in accordance with the orientation of lee slop could indicate primary wind direction in the case of complex transverse deposit but not to longitudinal or other complex bedforms. Accordingly, because of the variation of regional flow is filtrated by dune and flow interaction, the dip directions of most aeolian cross-strata except simple grainflow cross strata resulting from simple transve rse dunes could not accurately reflect paleaowind direction.%在腾格里沙漠东南缘对现代沙丘表面气流、沉积过程的野外观测结果表明,由于区域气流、沙丘形态及其相互作用等的不同使沙丘背风坡气流发生变化,在此发现三种背风坡次生气流:分离流、附体未偏向流和附体偏向流。前者以弱的反向流为特征多发生在横向气流条件下坡度较陡的背

  2. Solubility limits on radionuclide dissolution

    Energy Technology Data Exchange (ETDEWEB)

    Kerrisk, J.F.

    1984-12-31

    This paper examines the effects of solubility in limiting dissolution rates of a number of important radionuclides from spent fuel and high-level waste. Two simple dissolution models were used for calculations that would be characteristics of a Yucca Mountain repository. A saturation-limited dissolution model, in which the water flowing through the repository is assumed to be saturated with each waste element, is very conservative in that it overestimates dissolution rates. A diffusion-limited dissolution model, in which element-dissolution rates are limited by diffusion of waste elements into water flowing past the waste, is more realistic, but it is subject to some uncertainty at this time. Dissolution rates of some elements (Pu, Am, Sn, Th, Zr, Sm) are always limited by solubility. Dissolution rates of other elements (Cs, Tc, Np, Sr, C, I) are never solubility limited; their release would be limited by dissolution of the bulk waste form. Still other elements (U, Cm, Ni, Ra) show solubility-limited dissolution under some conditions. 9 references, 3 tables.

  3. Understanding the dissolution of zeolites.

    Science.gov (United States)

    Hartman, Ryan L; Fogler, H Scott

    2007-05-08

    Scientific knowledge of how zeolites, a unique classification of microporous aluminosilicates, undergo dissolution in aqueous hydrochloric acid solutions is limited. Understanding the dissolution of zeolites is fundamental to a number of processes occurring in nature and throughout industry. To better understand the dissolution process, experiments were carried out establishing that the Si-to-Al ratio controls zeolite framework dissolution, by which the selective removal of aluminum constrains the removal of silicon. Stoichiometric dissolution is observed for Type 4A zeolite in HCl where the Si-to-Al ratio is equal to 1.0. Framework silicon dissolves completely during Type 4A dissolution and is followed by silicate precipitation. However, for the zeolite analcime which has a Si-to-Al ratio of 2.0 dissolves non-stoichiometrically as the selective removal of aluminum results in partially dissolved silicate particles followed by silicate precipitation. In Type Y zeolite, exhibiting a Si-to-Al ratio of 3.0, there is insufficient aluminum to weaken the structure and cause silicon to dissolve in HCl. Thus, little or no precipitation is observed, and amorphous undissolvable silicate particles remain intact. The initial dissolution rates of Type Y and 4A zeolites demonstrate that dissolution is constrained by the number of available reaction sites, and a selective removal rate parameter is applied to delineate the mechanism of particle dissolution by demonstrating the kinetic influence of the Si-to-Al ratio. Zeolite framework models are constructed and used to undergird the basic dissolution mechanism. The framework models, scanning electron micrographs of partially dissolved crystals, and experimentally measured dissolution rates all demonstrate that a zeolite's Si-to-Al framework ratio plays a universal role in the dissolution mechanism, independent of framework type. Consequently, the unique mechanism of zeolite dissolution has general implications on how petroleum

  4. Biorelevant dissolution media

    DEFF Research Database (Denmark)

    Ilardia-Arana, David; Kristensen, Henning G; Müllertz, Anette

    2006-01-01

    Biorelevant dissolution media containing bile salt and lecithin at concentrations appropriate for fed and fasted state are useful when testing oral solid formulations of poorly water-soluble drugs. Dilution of amphiphile solutions affects the aggregation state of the amphiphiles because bile salt....... Dilution of the two- and four component media caused enlargement of the mixed micelles and formation of vesicles. The solubility of estradiol in the buffer solution was increased with addition of the amphiphiles. A good correlation (R(2) = 0.987) was found between estradiol solubility and mass...

  5. Dissolution in a field

    OpenAIRE

    Hwang, W.; Redner, S.

    2001-01-01

    We study the dissolution of a solid by continuous injection of reactive ``acid'' particles at a single point, with the reactive particles undergoing biased diffusion in the dissolved region. When acid encounters the substrate material, both an acid particle and a unit of the material disappear. We find that the lengths of the dissolved cavity parallel and perpendicular to the bias grow as t^{2/(d+1)} and t^{1/(d+1)}, respectively, in d-dimensions, while the number of reactive particles within...

  6. Insights into pharmaceutical nanocrystal dissolution: a molecular dynamics simulation study on aspirin.

    Science.gov (United States)

    Greiner, Maximilian; Elts, Ekaterina; Briesen, Heiko

    2014-09-02

    The presented molecular dynamics simulations are the first simulations to reveal dynamic dissolution of a pharmaceutical crystal in its experimentally determined shape. Continuous dissolution at constant undersaturation of the surrounding medium is ensured by introducing a plane of sticky dummy atoms into the water slab. These atoms have a strong interaction potential with dissolved aspirin molecules, but interactions with water are excluded from the calculations. Thus, the number of aspirin molecules diffusing freely in solution is kept at a low value and continuous dissolution of the aspirin crystal is monitored. Further insight into face-specific dissolution is drawn. The dissolution mechanism of receding edges is found for the (001) plane. These findings are in good agreement with experimental results. While the proposed dissolution mechanism for the (100) plane is terrace sinking on a rough surface, no pronounced dissolution of the perfectly flat face is seen in the present work. Molecular simulations of pharmaceuticals in their experimentally obtained structure therefore have shown to be especially suited for the investigation of dissolving faces, where the edges have a pronounced effect. In contrast to previous studies a propagation of the dissolution front into the crystal face is reported, and the crystal bulk is stable over the whole simulation time of 150 ns.

  7. Plutonium dissolution process

    Science.gov (United States)

    Vest, M.A.; Fink, S.D.; Karraker, D.G.; Moore, E.N.; Holcomb, H.P.

    1994-01-01

    A two-step process for dissolving Pu metal is disclosed in which two steps can be carried out sequentially or simultaneously. Pu metal is exposed to a first mixture of 1.0-1.67 M sulfamic acid and 0.0025-0.1 M fluoride, the mixture having been heated to 45-70 C. The mixture will dissolve a first portion of the Pu metal but leave a portion of the Pu in an oxide residue. Then, a mineral acid and additional fluoride are added to dissolve the residue. Alternatively, nitric acid between 0.05 and 0.067 M is added to the first mixture to dissolve the residue as it is produced. Hydrogen released during the dissolution is diluted with nitrogen.

  8. Plutonium dissolution process

    Science.gov (United States)

    Vest, Michael A.; Fink, Samuel D.; Karraker, David G.; Moore, Edwin N.; Holcomb, H. Perry

    1996-01-01

    A two-step process for dissolving plutonium metal, which two steps can be carried out sequentially or simultaneously. Plutonium metal is exposed to a first mixture containing approximately 1.0M-1.67M sulfamic acid and 0.0025M-0.1M fluoride, the mixture having been heated to a temperature between 45.degree. C. and 70.degree. C. The mixture will dissolve a first portion of the plutonium metal but leave a portion of the plutonium in an oxide residue. Then, a mineral acid and additional fluoride are added to dissolve the residue. Alteratively, nitric acid in a concentration between approximately 0.05M and 0.067M is added to the first mixture to dissolve the residue as it is produced. Hydrogen released during the dissolution process is diluted with nitrogen.

  9. 12 CFR 546.4 - Voluntary dissolution.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Voluntary dissolution. 546.4 Section 546.4... ASSOCIATIONS-MERGER, DISSOLUTION, REORGANIZATION, AND CONVERSION § 546.4 Voluntary dissolution. A Federal savings association's board of directors may propose a plan for dissolution of the association. The plan...

  10. Size effects in MgO cube dissolution.

    Science.gov (United States)

    Baumann, Stefan O; Schneider, Johannes; Sternig, Andreas; Thomele, Daniel; Stankic, Slavica; Berger, Thomas; Grönbeck, Henrik; Diwald, Oliver

    2015-03-10

    Stability parameters and dissolution behavior of engineered nanomaterials in aqueous systems are critical to assess their functionality and fate under environmental conditions. Using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction, we investigated the stability of cubic MgO particles in water. MgO dissolution proceeding via water dissociation at the oxide surface, disintegration of Mg(2+)-O(2-) surface elements, and their subsequent solvation ultimately leads to precipitation of Mg(OH)2 nanosheets. At a pH ≥ 10, MgO nanocubes with a size distribution below 10 nm quantitatively dissolve within few minutes and convert into Mg(OH)2 nanosheets. This effect is different from MgO cubes originating from magnesium combustion in air. With a size distribution in the range 10 nm ≤ d ≤ 1000 nm they dissolve with a significantly smaller dissolution rate in water. On these particles water induced etching generates (110) faces which, above a certain face area, dissolve at a rate equal to that of (100) planes.1 The delayed solubility of microcrystalline MgO is attributed to surface hydroxide induced self-inhibition effects occurring at the (100) and (110) microplanes. The present work underlines the importance of morphology evolution and surface faceting of engineered nanomaterials particles during their dissolution.

  11. Face pain

    Science.gov (United States)

    ... begin in other places in the body. Abscessed tooth (ongoing throbbing pain on one side of the lower face that ... face, and aggravated by eating. Call a dentist. Pain is persistent, ... by other unexplained symptoms. Call your primary provider.

  12. Dissolution Threats and Legislative Bargaining

    DEFF Research Database (Denmark)

    Becher, Michael; Christiansen, Flemming Juul

    2015-01-01

    Chief executives in many parliamentary democracies have the power to dissolve the legislature. Despite a well-developed literature on the endogenous timing of parliamentary elections, political scientists know remarkably little about the strategic use of dissolution power to influence policymaking....... To address this gap, we propose and empirically evaluate a theoretical model of legislative bargaining in the shadow of executive dissolution power. The model implies that the chief executive's public support and legislative strength, as well as the time until the next constitutionally mandated election......, are important determinants of the use and effectiveness of dissolution threats in policymaking. Analyzing an original time-series data set from a multiparty parliamentary democracy, we find evidence in line with key empirical implications of the model....

  13. Role of Solvents in Improvement of Dissolution Rate of Drugs: Crystal Habit and Crystal Agglomeration

    Directory of Open Access Journals (Sweden)

    Maryam Maghsoodi

    2015-03-01

    Full Text Available Crystallization is often used for manufacturing drug substances. Advances of crystallization have achieved control over drug identity and purity, but control over the physical form remains poor. This review discusses the influence of solvents used in crystallization process on crystal habit and agglomeration of crystals with potential implication for dissolution. According to literature it has been known that habit modification of crystals by use of proper solvents may enhance the dissolution properties by changing the size, number and the nature of crystal faces exposed to the dissolution medium. Also, the faster dissolution rate of drug from the agglomerates of crystals compared with the single crystals may be related to porous structure of the agglomerates and consequently their better wettability. It is concluded from this review that in-depth understanding of role of the solvents in crystallization process can be applied to engineering of crystal habit or crystal agglomeration, and predictably dissolution improvement in poorly soluble drugs.

  14. Empirical Modeling of Metal Oxides Dissolution

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seon-Byeong; Won, Hui-Jun; Park, Sang-Yoon; Moon, Jei-Kwon; Choi, Wang-Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    There have been tons of studies to examine the dissolution of metal oxides in terms of dissolution kinetics, type of reactants, geometry, etc. However, most of previous studies is the observation of macroscopic dissolution characteristics and might not provide the atomic scale characteristics of dissolution reactions. Even the analysis of microscopic structure of metal oxide with SEM, XRD, etc. during the dissolution does not observe the microscopic characteristics of dissolution mechanism. Computational analysis with well-established dissolution model is the one of the best approaches to understand indirectly the microscopic dissolution behaviour. Various designs of experimental conditions are applied to the in-vitro methods interpreting the dissolution characteristics controlled by each influencing parameter.

  15. Actor bonds after relationship dissolution

    DEFF Research Database (Denmark)

    Skaates, Maria Anne

    2000-01-01

    Most of the presented papers at the 1st NoRD Workshop can be classified as belonging to the business marketing approach to relationship dissolution. Two papers were conceptual, and the remaining six were empirical studies. The first conceptual study by Skaates (2000) focuses on the nature...... of the actor bonds that remain after a business relationship has ended. The study suggests that an interdisciplinary approach would provide a richer understanding of the phenomenon; this could be achieved by using e.g. Bourdieu's sociological concepts in dissolution research....

  16. Actor bonds after relationship dissolution

    DEFF Research Database (Denmark)

    Skaates, Maria Anne

    2000-01-01

    Most of the presented papers at the 1st NoRD Workshop can be classified as belonging to the business marketing approach to relationship dissolution. Two papers were conceptual, and the remaining six were empirical studies. The first conceptual study by Skaates (2000) focuses on the nature...... of the actor bonds that remain after a business relationship has ended. The study suggests that an interdisciplinary approach would provide a richer understanding of the phenomenon; this could be achieved by using e.g. Bourdieu's sociological concepts in dissolution research....

  17. NONMETALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>20111761 Chen Hua(115 Geological Party,Guizhou Bureau of Geology and Mineral Exploration & Development,Guiyang 551400,China);Deng Chao Analysis on the Metallogenic Environment of Maochang Bauxite in Guizhou Province(Guizhou Geology,ISSN1000-5943,CN52-1059/P,27(3),2010,p.198-201,2 illus.,1 table,8 refs.)Key words:bauxite deposit,Guizhou Province By long time physical and chemical process,the carbonate rock after Central Guizhou uplidft,becomes red clay,after further weathering,the red clay decomposed into the oxide,hydroxide of Al and Fe,in the dissolution hole and depression,it concentrates primary fragmentary tight and earthy karst bauxite ore.Because the variation of landform,it decomposes and cracks again,affords the material source

  18. Quartz dissolution. I - Negative crystal experiments and a rate law. II - Theory of rough and smooth surfaces

    Science.gov (United States)

    Gratz, Andrew J.; Bird, Peter

    1993-01-01

    The range of the measured quartz dissolution rates, as a function of temperature and pOH, extent of saturation, and ionic strength, is extended to cover a wider range of solution chemistries, using the negative crystal methodology of Gratz et al. (1990) to measure the dissolution rate. A simple rate law describing the quartz dissolution kinetics above the point of zero charge of quartz is derived for ionic strengths above 0.003 m. Measurements were performed on some defective crystals, and the mathematics of step motion was developed for quartz dissolution and was compared with rough-face behavior using two different models.

  19. EFFECT OF NON IONIC SURFACTANT ON THE SOLUBILITY AND DISSOLUTION OF SIMVASTATIN

    Directory of Open Access Journals (Sweden)

    Kumar Sandeep

    2011-03-01

    Full Text Available Various investigators have been facing the problems in improving solubility, dissolution and bioavailability of poorly water soluble drugs. Solid dispersion is a unique approach to improve the solubility of poorly water soluble drugs. In the present study an attempt has been made to improve the solubility and dissolution of poorly soluble drug Simvastatin (SIM using Poloxamer 188 (PXM as carrier. The kneading technique was used to prepare solid dispersions in different ratios. In conclusion, solubility and dissolution enhancement of SIM was improved by preparing its solid dispersion with PXM.

  20. Development of practical application technology for photovoltaic power generation systems in fiscal 1997. Development of technologies to manufacture thin film solar cells, development of technologies to manufacture low-cost large-area modules (dissolution and deposition process); 1997 nendo taiyoko hatsuden system jitsuyoka gijutsu kaihatsu. Usumaku taiyo denchi no seizo gijutsu kaihatsu, tei cost daimenseki module seizo gijutsu kaihatsu (yokai sekishutsuho)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    Research and development was performed by noticing on the plasma spraying method as a process that can manufacture thin poly-crystalline silicon films at a high speed. Fiscal 1997 has established a technology that can form a silicon film directly without using seed crystals in an area of 2-cm square on a carbon supported substrate by using a small film manufacturing equipment using the dissolution and deposition process. The size of the crystal is as very large as several hundred {mu}m, by which a possibility of making high-performance solar cells was verified. Discussions were given to apply this technology to large-area substrates, whereas a device was developed, which is capable of forming a film in an area corresponding to 10-cm square. According to a film forming experiment using this device, the film has begun being formed on part of a 10-cm square substrate, verifying the effectiveness of this method. While the film thickness is about 100 {mu}m, it was confirmed that the crystal size will not change even if the thickness is made mechanically as thin as about 50 {mu}m. Further discussions were given on enhancement of wettability by means of coating, and light enclosing structure. (NEDO)

  1. Face-specific Replacement of Calcite by Amorphous Silica Nanoparticles

    Science.gov (United States)

    Liesegang, M.; Milke, R.; Neusser, G.; Mizaikoff, B.

    2016-12-01

    Amorphous silica, composed of nanoscale spheres, is an important biomineral, alteration product of silicate rocks on the Earth's surface, and precursor material for stable silicate minerals. Despite constant progress in silica sphere synthesis, fundamental knowledge of natural silica particle interaction and ordering processes leading to colloidal crystals is absent so far. To understand the formation pathways of silica spheres in a geologic environment, we investigated silicified Cretaceous mollusk shell pseudomorphs from Coober Pedy (South Australia) using focused ion beam (FIB)-SEM tomography, petrographic microscopy, µ-XRD, and EMPA. The shells consist of replaced calcite crystals (product, the advancement of synchronized dissolution and precipitation fronts along lattice planes is essential. We assume that the volume-preserving replacement process proceeds via a face-specific dissolution-precipitation mechanism with intermediate subparticle aggregation and subsequent layer-by-layer deposition of spheres along a planar surface. Porosity created during the replacement reaction allows permanent fluid access to the propagating reaction interface. Fluid pH and ionic strength remain constant throughout the replacement process, permitting continuous silica nanoparticle formation and diffusion-limited colloid aggregation. Our study provides a natural example of the transformation of an atomic crystal to an amorphous, mesoscale ordered material; thus, links the research fields of natural colloidal crystal formation, carbonate-silica replacement, and crystallization by oriented particle aggregation (CPA).

  2. Controls by saturation state on etch pit formation during calcite dissolution

    Science.gov (United States)

    Teng, H. Henry

    2004-01-01

    Dissolution experiments were conducted on {101¯4} cleavage faces of calcite at various under-saturations to determine how the saturation state controls etch pit formation. Experimental observations were made by using in situ fluid cell Atomic Force Microscopy. Three dissolution modes were observed. When the saturation index Ω > 0.541, no etch pit formation was seen and dissolution primarily occurred at existing steps. When Ω decreased to Ω c = 0.541-0.410, the first visible pits appeared and continuous reduction in saturation state slowly increased the pit density on terraces while dissolution simultaneously proceeded at step edges. Finally, when the saturation state fell below Ω max = ˜0.007, a precipitous increase in pit density took place that sharply contrasted to the ordered fashion of pit formation observed at saturation conditions above this level. These observations are interpreted to be two-dimensional and unassisted pit formation at Ω 0.541. The values of Ω c are in good agreement with the dislocation theory's predicted critical under-saturations for pit formation at line dislocations. The occurrence of Ω max is not directly predicted but is a logical consequence of dissolution thermodynamics. These findings suggest that (1) dissolution near and far from equilibrium (i.e., Ω > Ω c, Ω unassisted pit nucleation at Ω ˜ Ω max is not predicted by the current dissolution rate equations. This suggests that an accurate 'general' rate law describing universal dissolution processes has yet to be developed.

  3. Simulating Succinate-Promoted Dissolution at Calcite {104} Steps

    Science.gov (United States)

    Mkhonto, D.; Sahai, N.

    2008-12-01

    Organic molecules of a wide range of molecular weights from small organic acids, amino-acids, acidic peptides and acidic proteins to humic and fulvic acids play a key role in modulating nucleation, crystal growth and dissolution of calcium carbonate polymorphs. In general, these acidic molecules inhibit calcite growth and, promote dissolution preferentially along specific crystallographic directions, in the process, regulating crystal shape and size, and even whether a metastable polymorph (e.g., vaterite or aragonite) is nucleated first. For example, chiral faces of calcite are selected by chiral amino-acids and the unusual {hk0} faces are expressed in the presence of amino-acids [Orme et al., 2001], and unusual heptagonal dissolution etch-pit are seen in the presence of succinate compared to the normal rhombohedral pits in water alone [Teng et al., 2006]. Thus, the presence of unusual crystal morphologies may indicate organic-mediated growth, thus serving as a biosignature. We have conducted the Molecular Dynamics (MD) simulations using the Consistent Valence Force Field (CVFF) as implemented in the FORCITE© module of the Materials Studio © software package (Accelrys, Inc. TM) to model the adsorption of succinate, a dicarboxylic acid, and charge- balancing Na+ ions on dry and hydrated steps in different directions on the {104} cleavage face of calcite [Mkhonto and Sahai, in prep.]. At the site of succinate adsorption, we find elongation of the interatomic distances (Ca-OCO3,i) between surface Ca2+ cation and the oxygen of the underlying inorganic CO32- anion the first surface layer of calcite, compared to the corresponding distances in the presence of water alone, suggesting greater ease of surface Ca2+ detachment. This result is consistent with the empirically observed increase in overall dissolution rate with succinate [Teng et al., 2006]. Furthermore, succinate adsorption lowers the step energies, which explains the appearance of steps in the unsusual [42

  4. 25 CFR 11.606 - Dissolution proceedings.

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Dissolution proceedings. 11.606 Section 11.606 Indians... ORDER CODE Domestic Relations § 11.606 Dissolution proceedings. (a) Either or both parties to the marriage may initiate dissolution proceedings. (b) If a proceeding is commenced by one of the parties,...

  5. 25 CFR 11.605 - Dissolution.

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Dissolution. 11.605 Section 11.605 Indians BUREAU OF... Domestic Relations § 11.605 Dissolution. (a) The Court of Indian Offenses shall enter a decree of dissolution of marriage if: (1) The court finds that the marriage is irretrievably broken, if the finding is...

  6. Dissolution behavior and dissolution mechanism of palygorskite in HCl solution

    Institute of Scientific and Technical Information of China (English)

    CAI Yuanfeng; XUE Jiyue

    2004-01-01

    The 1 mol/L, 3 mol/L and 5 mol/L HCl solutions were employed to leach two palygorskites with different trioctahedral contents in their crystal structure for different period of time. The results of the dissolution experiments show that the dissolution process could be divided into three steps, and that this dissolution behavior can be attributed to its higher Mg2+ content, and is restricted by the extraction behavior of Si4+. The preferential extraction for Mg2+ promotes the extraction behavior of Si4+ from Si-O framework. Because the Si4+ in the form of amorphous SiO2 is adsorbed onto the surface of palygorskite fibre, the reaction between palygorskite and acid is obstructed. With the elapsing of time, or the increasing of the acid concentration, the amorphous SiO2 flocculates, and then the channels of chemical reaction are reopened. The ratio value of Mg2+/(Fe3++Al3+) in leaching solution tends to a fixed value, showing that the acid attacks not only the surface but also the structural channels. There are no obvious three steps observed during the acid attack on the palygorskite with a lower trioctahedral content. The differential behavior for two palygorskites is discussed.

  7. Modeling dissolution in aluminum alloys

    Science.gov (United States)

    Durbin, Tracie Lee

    2005-07-01

    Aluminum and its alloys are used in many aspects of modern life, from soda cans and household foil to the automobiles and aircraft in which we travel. Aluminum alloy systems are characterized by good workability that enables these alloys to be economically rolled, extruded, or forged into useful shapes. Mechanical properties such as strength are altered significantly with cold working, annealing, precipitation-hardening, and/or heat-treatments. Heat-treatable aluminum alloys contain one or more soluble constituents such as copper, lithium, magnesium, silicon and zinc that individually, or with other elements, can form phases that strengthen the alloy. Microstructure development is highly dependent on all of the processing steps the alloy experiences. Ultimately, the macroscopic properties of the alloy depend strongly on the microstructure. Therefore, a quantitative understanding of the microstructural changes that occur during thermal and mechanical processing is fundamental to predicting alloy properties. In particular, the microstructure becomes more homogeneous and secondary phases are dissolved during thermal treatments. Robust physical models for the kinetics of particle dissolution are necessary to predict the most efficient thermal treatment. A general dissolution model for multi-component alloys has been developed using the front-tracking method to study the dissolution of precipitates in an aluminum alloy matrix. This technique is applicable to any alloy system, provided thermodynamic and diffusion data are available. Treatment of the precipitate interface is explored using two techniques: the immersed-boundary method and a new technique, termed here the "sharp-interface" method. The sharp-interface technique is based on a variation of the ghost fluid method and eliminates the need for corrective source terms in the characteristic equations. In addition, the sharp-interface method is shown to predict the dissolution behavior of precipitates in aluminum

  8. Dissolution Kinetics of Alumina Calcine

    Energy Technology Data Exchange (ETDEWEB)

    Batcheller, Thomas Aquinas

    2001-09-01

    Dissolution kinetics of alumina type non-radioactive calcine was investigated as part of ongoing research that addresses permanent disposal of Idaho High Level Waste (HLW). Calcine waste was produced from the processing of nuclear fuel at the Idaho Nuclear Technology and Engineering Center (INTEC). Acidic radioactive raffinates were solidified at ~500°C in a fluidized bed reactor to form the dry granular calcine material. Several Waste Management alternatives for the calcine are presented in the Idaho High Level Waste Draft EIS. The Separations Alternative addresses the processing of the calcine so that the HLW is ready for removal to a national geological repository by the year 2035. Calcine dissolution is the key front-end unit operation for the separations alternative.

  9. Development of dissolution method for benznidazole tablets

    Directory of Open Access Journals (Sweden)

    Ádley Antonini Neves de Lima

    2009-01-01

    Full Text Available The aim of this work was the development of a dissolution method for benznidazole (BNZ tablets. Three different types of dissolution media, two stirring speeds and apparatus 2 (paddle were used. The accomplishment of the drug dissolution profiles was compared through the dissolution efficiency. The assay was performed by spectrophotometry at 324 nm. The better conditions were: sodium chloridehydrochloride acid buffer pH 1.2 with stirring speed of 75 rpm, volume of 900 mL and paddle as apparatus. Ahead of the results it can be concluded that the method developed consists in an efficient alternative for assays of dissolution for benznidazole tablets.

  10. Enhanced performance large volume dissolution-DNP

    DEFF Research Database (Denmark)

    Bowen, Sean; Ardenkjær-Larsen, Jan Henrik

    2014-01-01

    A systematic study of the performance of the dissolution process in dissolution-DNP is presented. A relatively simple set of modifications is made to the standard Hypersense dissolution system to enable polarization of large volume samples. These consist of a large volume sample cup along...... with supporting modifications to the dissolution head and related components. Additional modifications were made to support the mapping of the temperature/pressure space of the dissolution process as well as enabling the use of large volumes of solvent and improving the robustness of the system. No loss...

  11. After adoption: dissolution or permanence?

    Science.gov (United States)

    Festinger, Trudy

    2002-01-01

    Results are presented on the whereabouts of 516 adopted children, based on a random sample of children adopted from placement in New York City in 1996. Data from interviews with adoptive parents were augmented by information from adoption subsidy records and state child tracking files, as well as interviews with caregivers of children whose adoptive parents were deceased. There were few dissolutions, but postadoption service needs were many.

  12. Steadily translating parabolic dissolution fingers

    CERN Document Server

    Kondratiuk, Paweł

    2015-01-01

    Dissolution fingers (or wormholes) are formed during the dissolution of a porous rock as a result of nonlinear feedbacks between the flow, transport and chemical reactions at pore surfaces. We analyze the shapes and growth velocities of such fingers within the thin-front approximation, in which the reaction is assumed to take place instantaneously with the reactants fully consumed at the dissolution front. We concentrate on the case when the main flow is driven by the constant pressure gradient far from the finger, and the permeability contrast between the inside and the outside of the finger is finite. Using Ivantsov ansatz and conformal transformations we find the family of steadily translating fingers characterized by a parabolic shape. We derive the reactant concentration field and the pressure field inside and outside of the fingers and show that the flow within them is uniform. The advancement velocity of the finger is shown to be inversely proportional to its radius of curvature in the small P\\'{e}clet...

  13. Rapid and gradual modes of aerosol trace metal dissolution in seawater

    Directory of Open Access Journals (Sweden)

    Katherine Rose Marie Mackey

    2015-01-01

    Full Text Available Atmospheric deposition is a major source of trace metals in marine surface waters and supplies vital micronutrients to phytoplankton, yet measured aerosol trace metal solubility values are operationally defined and there are relatively few multi-element studies on aerosol-metal solubility in seawater. Here we measure the solubility of aluminum (Al, cadmium (Cd, cobalt (Co, copper (Cu, iron (Fe, manganese (Mn, nickel (Ni, lead (Pb, and zinc (Zn from natural aerosol samples in seawater over a 7 day period to (1 evaluate the role of extraction time in trace metal dissolution behavior and (2 explore how the individual dissolution patterns could influence biota. Dissolution behavior occurs over a continuum ranging from rapid dissolution, in which the majority of soluble metal dissolved immediately upon seawater exposure (Cd and Co in our samples, to gradual dissolution, where metals dissolved slowly over time (Zn, Mn, Cu, and Al in our samples. Additionally, dissolution affected by interactions with particles was observed in which a decline in soluble metal concentration over time occurred (Fe and Pb in our samples. Natural variability in aerosol chemistry between samples can cause metals to display different dissolution kinetics in different samples, and this was particularly evident for Ni, for which samples showed a broad range of dissolution rates. The elemental molar ratio of metals in the bulk aerosols was 23,189Fe: 22,651Al: 445Mn: 348Zn: 71Cu: 48Ni: 23Pb: 9Co: 1Cd, whereas the seawater soluble molar ratio after 7 days of leaching was 11Fe: 620Al: 205Mn: 240Zn: 20Cu: 14Ni: 9Pb: 2Co: 1Cd. The different kinetics and ratios of aerosol metal dissolution have implications for phytoplankton nutrition, and highlight the need for unified extraction protocols that simulate aerosol metal dissolution in the surface ocean.

  14. About Face

    Medline Plus

    Full Text Available Skip to Content Menu Closed (Tap to Open) Home Videos by Topic Videos by Type Search All ... What is AboutFace? Resources for Professionals Get Help Home Watch Videos by Topic Videos by Type Search ...

  15. About Face

    Medline Plus

    Full Text Available ... Home Videos by Topic Videos by Type Search All Videos PTSD Basics PTSD Treatment What is AboutFace? ... Watch Videos by Topic Videos by Type Search All Videos Learn More PTSD Basics PTSD Treatment What ...

  16. Face Forward

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Last November, surgeons in France successfully performed the world's first face transplant surgery. Ten days later, Chen Huanran in Beijing began soliciting patients who were ready to accept a face transplant, searching for China's first such patient through an advertisement on his website and other channels. Chen, chief orthopedic surgeon at the Plastic Surgery Hospital under the Chinese Academy of Medical Sciences, has conducted more than 300 transsexual operations and was considered one of the top com...

  17. Classification of dissolution profiles in terms of fractional dissolution rate and a novel measure of heterogeneity.

    Science.gov (United States)

    Lánský, Petr; Weiss, Michael

    2003-08-01

    Dissolution profiles are classified in accordance with the shape of fractional dissolution rate function. This function is constant in time for the classical first-order model and, in this case, the dissolution is described by a monoexponential function. Therefore, any deviation of the fractional dissolution rate from the constant level suggests the presence of different (nonlinear/nonhomogenous) mechanisms in the dissolution process. The shapes of the fractional dissolution rate depend on the type of the model of dissolution; thus, classification with respect to this function is proposed as a tool for model selection. The Kullback-Leibler information distance is proposed for measuring similarity between two different drug dissolution profiles. The method is applied mainly to compare the first-order model, which characterizes a homogenous dosage form, with other common descriptors of dissolution and with experimental data.

  18. Solvent mediated stabilisation of dissolution at the resorcinol-water interface

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, M.; Sahudin, S. [Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur (Malaysia)

    2010-02-15

    Experimental evidence suggests dissolution along the polar c-axis of {alpha}-resorcinol in water preferentially occurs at the {l_brace}011{r_brace} surface. In an attempt to understand the mechanism by which solvent influences this process, dissolution at the resorcinol {l_brace}011{r_brace} and {l_brace}011{r_brace} surfaces has been studied using molecular dynamics simulations. Our computations indicate dissolution at the two faces is dependent upon solvent behaviour at the crystal surface, where strong water-crystal interactions serve to stabilise the crystal surface and retard dissolution. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. DISSOLUTION OF NEPTUNIUM OXIDE RESIDUES

    Energy Technology Data Exchange (ETDEWEB)

    Kyser, E

    2009-01-12

    This report describes the development of a dissolution flowsheet for neptunium (Np) oxide (NpO{sub 2}) residues (i.e., various NpO{sub 2} sources, HB-Line glovebox sweepings, and Savannah River National Laboratory (SRNL) thermogravimetric analysis samples). Samples of each type of materials proposed for processing were dissolved in a closed laboratory apparatus and the rate and total quantity of off-gas were measured. Samples of the off-gas were also analyzed. The quantity and type of solids remaining (when visible) were determined after post-dissolution filtration of the solution. Recommended conditions for dissolution of the NpO{sub 2} residues are: Solution Matrix and Loading: {approx}50 g Np/L (750 g Np in 15 L of dissolver solution), using 8 M nitric acid (HNO{sub 3}), 0.025 M potassium fluoride (KF) at greater than 100 C for at least 3 hours. Off-gas: Analysis of the off-gas indicated nitric oxide (NO), nitrogen dioxide (NO{sub 2}) and nitrous oxide (N{sub 2}O) as the only identified components. No hydrogen (H{sub 2}) was detected. The molar ratio of off-gas produced per mole of Np dissolved ranged from 0.25 to 0.4 moles of gas per mole of Np dissolved. A peak off-gas rate of {approx}0.1 scfm/kg bulk oxide was observed. Residual Solids: Pure NpO{sub 2} dissolved with little or no residue with the proposed flowsheet but the NpCo and both sweepings samples left visible solid residue after dissolution. For the NpCo and Part II Sweepings samples the residue amounted to {approx}1% of the initial material, but for the Part I Sweepings sample, the residue amounted to {approx}8 % of the initial material. These residues contained primarily aluminum (Al) and silicon (Si) compounds that did not completely dissolve under the flowsheet conditions. The residues from both sweepings samples contained minor amounts of plutonium (Pu) particles. Overall, the undissolved Np and Pu particles in the residues were a very small fraction of the total solids.

  20. Assessment of solvents for cellulose dissolution.

    Science.gov (United States)

    Ghasemi, Mohammad; Tsianou, Marina; Alexandridis, Paschalis

    2017-03-01

    A necessary step in the processing of biomass is the pretreatment and dissolution of cellulose. A good solvent for cellulose involves high diffusivity, aggressiveness in decrystallization, and capability of disassociating the cellulose chains. However, it is not clear which of these factors and under what conditions should be improved in order to obtain a more effective solvent. To this end, a newly-developed phenomenological model has been applied to assess the controlling mechanism of cellulose dissolution. Among the findings, the cellulose fibers remain crystalline almost to the end of the dissolution process for decrystallization-controlled kinetics. In such solvents, decreasing the fiber crystallinity, e.g., via pretreatment, would result in a considerable increase in the dissolution rate. Such insights improve the understanding of cellulose dissolution and facilitate the selection of more efficient solvents and processing conditions for biomass. Specific examples of solvents are provided where dissolution is limited due to decrystallization or disentanglement.

  1. Gas dissolution in antibubble dynamics

    Science.gov (United States)

    Scheid, Benoit; Zawala, Jan; Dorbolo, Stéphane

    2014-11-01

    Antibubbles are ephemeral objects. Their lifetime is driven by the slow drainage of the air shell from the bottom to the top of the antibubble under the action of the hydrostatic pressure. We show in this work that this argument is only valid if the water used to make the surfactant mixture is saturated in air. Otherwise, two paths are used by the air that conducts to the thinning and the eventual collapse of the air shell: the drainage from the bottom to the top of the antibubble and the dissolution of the air by the liquid. Using degassed water dramatically shortens the lifetime of the antibubbles, as observed experimentally and rationalised by time-dependent simulations. Consequently, the antibubble lifetime is not only correlated to physical and chemical properties of the air-liquid interface but also to the gas content of the liquid. We also show that pure gas dissolution does not depend on the antibubble radius, a behaviour that allows to rationalise unexplained experimental data found in the literature. We thank the F.R.S.-FNRS for financial support.

  2. About Face

    Medline Plus

    Full Text Available ... PTSD (posttraumatic stress disorder). Watch the intro This is AboutFace In these videos, Veterans, family members, and ... to hear what they have to say. What is PTSD? → How does PTSD affect loved ones? → Am ...

  3. About Face

    Medline Plus

    Full Text Available ... traumatic event — like combat, an assault, or a disaster — it's normal to feel scared, keyed up, or sad at first. But if it's been months or years since the trauma and you're not feeling better, you may have PTSD (posttraumatic stress disorder). Watch the intro This is AboutFace In ...

  4. Siliceous sponge spicule dissolution: In field experimental evidences from temperate and tropical waters

    Science.gov (United States)

    Bertolino, Marco; Cattaneo-Vietti, Riccardo; Pansini, Maurizio; Santini, Chiara; Bavestrello, Giorgio

    2017-01-01

    Sponge siliceous spicules are considered a sink in the silica balance of the oceans as their dissolution rate seems to be negligible, but no field data are available about this process. The aim of this study was a first evaluation of the quantitative dissolution rates of some demosponge and hexactinellid spicules (collected in different localities at different latitudes), left at sea for six months in two localities characterised by different water average temperatures: Mediterranean Sea and Celebes Sea. The effects of silica dissolution on the experimented spicules, studied by SEM analysis, produced an enlargement of the axial canal sometimes resulting in empty spicules. While in demosponges the axial canal wall of eroded spicules was perfectly smooth or slightly rough, the hexactinellid Rossella racovitzae showed a cavernous, well recognisable pattern of dissolution. The dissolution rates were determined evaluating the decrease in outer diameter and in the expansion of the axial channel of about 300 spicules for each considered species and locality. The spicules from the Mediterranean Geodia cydonium did not show any detectable dissolution in both localities, while those from Tethya citrina showed a loose of silica of about 23% in the Mediterranean and 47% in the Celebes Sea. Paratetilla bacca from the Red Sea decreased the silica content of about 30% in both the localities. Tetilla leptoderma from Mar del Plata lost about 8% and 42% of silica respectively in Mediterranean and Celebes Sea. Finally, the hexactinellid spicules from the Antarctic Rossella racovitzae showed highest dissolution rates in both experimental sites (37% and 66% in the Mediterranean and Celebes Sea, respectively). The different levels of dissolution can be related to the different taxonomic position in terms of specular structures as well as to the temperatures at which the spicules have been deposited and exposed. In fact, spicules from the same species showed a dissolution rate generally

  5. Prediction of dissolution-absorption relationships from a continuous dissolution/Caco-2 system.

    Science.gov (United States)

    Ginski, M J; Taneja, R; Polli, J E

    1999-01-01

    The objectives were 1) to design a continuous dissolution/Caco-2 system to predict the dissolution-absorption relationships for fast and slow dissolving formulations of piroxicam, metoprolol tartrate, and ranitidine HCl, and compare the predicted relationships with observed relationships from clinical studies; 2) to estimate the effect of croscarmellose sodium on ranitidine dissolution-absorption relationships; and 3) to estimate the effect of solubilizing agents on piroxicam dissolution-absorption relationships. A continuous dissolution/Caco-2 system was constructed from a dissolution apparatus and a diffusion cell, such that drug dissolution and permeation across a Caco-2 monolayer would occur sequentially and simultaneously. The continuous system generally matched observed dissolution-absorption relationships from clinical studies. For example, the system successfully predicted the slow metoprolol and slow ranitidiine formulations to be permeation-rate-limited. The system predicted the slow piroxicam formulation to be dissolution-rate-limited, and the fast piroxicam formulation to be permeation-rate-limited, in spite of piroxicam's high permeability and low solubility. Additionally, the system indicated croscarmellose sodium enhanced ranitidine permeability and predicted solubilizing agents to not modulate permeability. These results suggest a dissolution/Caco-2 system to be an experimentally based tool that may predict dissolution-absorption relationships from oral solid dosage forms, and hence the relative contributions of dissolution and permeation to oral drug absorption kinetics.

  6. A comparative study on the dissolution of magnetite

    Energy Technology Data Exchange (ETDEWEB)

    Won, Huijun; Park, Jungsoon; Jung, Chonghun; Choi, Wangkyu; Moon, Jeikwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-10-15

    Magnetite is the main iron oxide formed on the surface of iron-based metals especially in contact with coolant in nuclear power plants. It reduces the efficiency of water lines in water-cooled nuclear reactors. Many solution formulations have been developed to dissolve or to decontaminate metal surfaces from the oxide layers formed on the surface. The presence of Cr in the structural materials such as stainless steel could result in the formulation of Cr-substituted iron oxides, as Fe{sup 3+} (0.067 nm) and Cr {sup 3+} (0.064 nm) have similar ionic radii. The formation of solid solution between Cr{sub 2}O{sub 3} with hematite and magnetite is reported. The best method of removing the radioactive nuclides such as Co-60, impregnated / embedded in these oxides, is to dissolve the oxide deposit without affecting the base metal. Dissolution of simple iron oxides is normally carried out using organic (inorganic) acid, reducing agent and chelating agent. Recently, it was reported that the chelating agent in a decontamination formulation affects the bad environmental effect during the disposal period of the radioactive waste. In the present study, the dissolution characteristics of magnetite in citric acid hydrazine system, in nitric acid-hydrazine system and in dithionite-sodium citrate system were investigated. The objective of the study is to compare the dissolution performance of the 3 kinds of the candidate decontamination formulation.

  7. Reading faces and Facing words

    DEFF Research Database (Denmark)

    Robotham, Julia Emma; Lindegaard, Martin Weis; Delfi, Tzvetelina Shentova

    It has long been argued that perceptual processing of faces and words is largely independent, highly specialised and strongly lateralised. Studies of patients with either pure alexia or prosopagnosia have strongly contributed to this view. The aim of our study was to investigate how visual...

  8. Reading faces and Facing words

    DEFF Research Database (Denmark)

    Robotham, Julia Emma; Lindegaard, Martin Weis; Delfi, Tzvetelina Shentova

    performed within normal range on at least one test of visual categorisation, strongly suggesting that their abnormal performance with words and faces does not represent a generalised visuo-perceptual deficit. Our results suggest that posterior areas in both hemispheres may be critical for both reading...

  9. Prediction of dissolution-absorption relationships from a dissolution/Caco-2 system.

    Science.gov (United States)

    Ginski, M J; Polli, J E

    1999-01-15

    While the analysis of in vitro dissolution-in vivo absorption relationships from oral solid dosage forms provides biopharmaceutical insight and regulatory benefit, no well developed method exists to predict dissolution-absorption relationships a priori to human studies. The objective was to develop an integrated dissolution/Caco-2 system to predict dissolution-absorption relationships, and hence the contributions of dissolution and intestinal permeation to overall drug absorption for fast and slow formulations of piroxicam, metoprolol, and ranitidine. Dissolution studies were conducted on fast and slow dissolving immediate-release formulations of piroxicam, metoprolol tartrate, and ranitidine HCl. Dissolution samples were treated with concentrated buffers to render them suitable (i.e., isotonic and neutral pH) for Caco-2 monolayer permeation studies. The dissolution/Caco-2 system yielded a predicted dissolution-absorption relationship for each formulation which matched the observed relationship from clinical studies. The dissolution/Caco-2 system's prediction of dissolution or permeation rate-limited absorption also agreed with the clinical results. For example, the dissolution/Caco-2 system successfully predicted the slow piroxicam formulation to be dissolution rate-limited, and the fast piroxicam formulation to be permeation rate-limited. Moreover, the system predicted this change from dissolution rate-limited absorption for slow piroxicam to permeation rate-limited absorption for fast piroxicam, in spite of piroxicam's high permeability and low solubility. The dissolution/Caco-2 system may prove to be a valuable tool in formulation development. Broader evaluation of such a system is warranted.

  10. Quantified Faces

    DEFF Research Database (Denmark)

    Sørensen, Mette-Marie Zacher

    2016-01-01

    Abstract: The article presents three contemporary art projects that, in various ways, thematise questions regarding numerical representation of the human face in relation to the identification of faces, for example through the use of biometric video analysis software, or DNA technology. The Dutch...... and critically examine bias in surveillance technologies, as well as scientific investigations, regarding the stereotyping mode of the human gaze. The American artist Heather Dewey-Hagborg creates three-dimensional portraits of persons she has “identified” from their garbage. Her project from 2013 entitled....... The three works are analysed with perspectives to historical physiognomy and Francis Galton's composite portraits from the 1800s. It is argued that, rather than being a statistical compression like the historical composites, contemporary statistical visual portraits (composites) are irreversible...

  11. CALCIUM CARBONATE DISSOLUTION RATE IN LIMESTONE CONTACTORS

    Science.gov (United States)

    The rate of carbonate mineral dissolution from limestone was studied using a rotating disk apparatus and samples of limestone of varied composition. The purpose of this study was to determine the effect of limestone composition on the kinetics of carbonate mineral dissolution. Th...

  12. Dissolution enhancement of tadalafil by liquisolid technique.

    Science.gov (United States)

    Lu, Mei; Xing, Haonan; Yang, Tianzhi; Yu, Jiankun; Yang, Zhen; Sun, Yanping; Ding, Pingtian

    2017-02-01

    This study aimed to enhance the dissolution of tadalafil, a poorly water-soluble drug by applying liquisolid technique. The effects of two critical formulation variables, namely drug concentration (17.5% and 35%, w/w) and excipients ratio (10, 15 and 20) on dissolution rates were investigated. Pre-compression tests, including particle size distribution, flowability determination, Fourier transform infrared (FT-IR), differential scanning calorimetry (DSC), X-ray diffractometry (XRD) and scanning electron microscopy (SEM), were carried out to investigate the mechanism of dissolution enhancement. Tadalafil liquisolid tablets were prepared and their quality control tests, dissolution study, contact angle measurement, Raman mapping, and storage stability test were performed. The results suggested that all the liquisolid tablets exhibited significantly higher dissolution rates than the conventional tablets and pure tadalafil. FT-IR spectrum reflected no drug-excipient interactions. DSC and XRD studies indicated reduction in crystallinity of tadalafil, which was further confirmed by SEM and Raman mapping outcomes. The contact angle measurement demonstrated obvious increase in wetting property. Taken together, the reduction of particle size and crystallinity, and the improvement of wettability were the main mechanisms for the enhanced dissolution rate. No significant changes were observed in drug crystallinity and dissolution behavior after storage based on XRD, SEM and dissolution results.

  13. Emotional and Cognitive Coping in Relationship Dissolution

    Science.gov (United States)

    Wrape, Elizabeth R.; Jenkins, Sharon Rae; Callahan, Jennifer L.; Nowlin, Rachel B.

    2016-01-01

    Dissolution of a romantic relationship can adversely affect functioning among college students and represents one primary reason for seeking campus counseling. This study examined the associations among common coping strategies and distress following relationship dissolution. Avoidance and repetitive negative thinking (RNT) were significantly…

  14. Dissolution of calcite in the twilight zone: bacterial control of dissolution of sinking planktonic carbonates is unlikely.

    Directory of Open Access Journals (Sweden)

    Andrew Bissett

    Full Text Available We investigated the ability of bacterial communities to colonize and dissolve two biogenic carbonates (Foraminifera and oyster shells. Bacterial carbonate dissolution in the upper water column is postulated to be driven by metabolic activity of bacteria directly colonising carbonate surfaces and the subsequent development of acidic microenvironments. We employed a combination of microsensor measurements, scanning electron microscopy (SEM, confocal laser scanning microscopy (CLSM and image analysis and molecular documentation of colonising bacteria to monitor microbial processes and document changes in shell surface topography. Bacterial communities rapidly colonised shell surfaces, forming dense biofilms with extracellular polymeric substance (EPS deposits. Despite this, we found no evidence of bacterially mediated carbonate dissolution. Dissolution was not indicated by Ca²⁺ microprofiles, nor was changes in shell surface structure related to the presence of colonizing bacteria. Given the short time (days settling carbonate material is actually in the twilight zone (500-1000 m, it is highly unlikely that microbial metabolic activity on directly colonised shells plays a significant role in dissolving settling carbonates in the shallow ocean.

  15. Effect of crystal habit on the dissolution behaviour of simvastatin crystals and its relationship to crystallization solvent properties.

    Science.gov (United States)

    Bukovec, P; Benkic, P; Smrkolj, M; Vrecer, F

    2016-05-01

    Simvastatin crystals, having same crystal structure but different types of habits and hence different intrinsic dissolution rate, were prepared by recrystallization from solvents selected according to their polarity index. Scanning electron microscopy, laser diffraction, image analysis, X-ray powder diffractometry, Fourier transform infrared spectroscopy and differential scanning calorimetry were used to investigate the physicochemical characteristics of the prepared crystals. The isolated crystals exhibited different crystal habits but possessed the same internal crystal structure. In this study the comparative intrinsic dissolution behaviour of the simvastatin crystals with different types of habits was studied and explained by surface energy and correlated to different solvent systems that were used for crystallization. In our work we diminished the influence of all other physical parameters that could influence the dissolution rate, e.g. particle size, specific surface area and polymorphism in order to focus the study onto the impact of crystal shape itself on the dissolution rate of simvastatin crystals. Rod shaped crystals isolated from more hydrophilic solvent mixture dissolved faster than plate-like crystals obtained from solvent mixture with lower polarity index. We correlated this fact to the different growth rate of the individual faces which resulted in different relative size of the individual crystal faces exposed to the dissolution medium as well as the chemical nature of those faces which in turn influenced the wettability and subsequent dissolution of the active pharmaceutical ingredient.

  16. Dissolution enthalpies of cellulose in ionic liquids.

    Science.gov (United States)

    Parviainen, Helena; Parviainen, Arno; Virtanen, Tommi; Kilpeläinen, Ilkka; Ahvenainen, Patrik; Serimaa, Ritva; Grönqvist, Stina; Maloney, Thaddeus; Maunu, Sirkka Liisa

    2014-11-26

    In this work, interactions between cellulose and ionic liquids were studied calorimetrically and by optical microscopy. Two novel ionic liquids (1,5-Diazabicyclo[4.3.0]non-5-enium propionate and N-methyl-1,5-diazabicyclo[4.3.0]non-5-enium dimethyl phosphate) and 1-ethyl-3-methylimidazolium acetate-water mixtures were used as solvents. Optical microscopy served in finding the extent of dissolution and identifying the dissolution pattern of the cellulose sample. Calorimetric studies identified a peak relating to dissolution of cellulose in solvent. The transition did, however, not indicate complete dissolution, but rather dissolution inside fibre or fibrils. This method was used to study differences between four cellulose samples with different pretreatment or origins.

  17. Premarital cohabitation and subsequent marital dissolution: a matter of self-selection?

    Science.gov (United States)

    Lillard, L A; Brien, M J; Waite, L J

    1995-08-01

    Married couples who began their relationship by cohabiting appear to face an increased risk of marital dissolution, which may be due to self-selection of more dissolution-prone individuals into cohabitation before marriage. This paper uses newly developed econometric methods to explicitly address the endogeneity of cohabitation before marriage in the hazard of marital disruption by allowing the unobserved heterogeneity components to be correlated across the decisions to cohabit and to end a marriage. These methods are applied to data from the National Longitudinal Study of the High School Class of 1972. We find significant heterogeneity in both cohabitation and marriage disruption, and discover evidence of self-selection into cohabitation.

  18. Molecular dynamic simulations of ocular tablet dissolution.

    Science.gov (United States)

    Ru, Qian; Fadda, Hala M; Li, Chung; Paul, Daniel; Khaw, Peng T; Brocchini, Steve; Zloh, Mire

    2013-11-25

    Small tablets for implantation into the subconjunctival space in the eye are being developed to inhibit scarring after glaucoma filtration surgery (GFS). There is a need to evaluate drug dissolution at the molecular level to determine how the chemical structure of the active may correlate with dissolution in the nonsink conditions of the conjunctival space. We conducted molecular dynamics simulations to study the dissolution process of tablets derived from two drugs that can inhibit fibrosis after GFS, 5-fluorouracil (5-FU) and the matrix metalloprotease inhibitor (MMPi), ilomastat. The dissolution was simulated in the presence of simple point charge (SPC) water molecules, and the liquid turnover of the aqueous humor in the subconjunctival space was simulated by removal of the dissolved drug molecules at regular intervals and replacement by new water molecules. At the end of the simulation, the total molecular solvent accessible surface area of 5-FU tablets increased by 60 times more than that of ilomastat as a result of tablet swelling and release of molecules into solution. The tablet dissolution pattern shown in our molecular dynamic simulations tends to correlate with experimental release profiles. This work indicates that a series of molecular dynamic simulations can be used to predict the influence of the molecular properties of a drug on its dissolution profile and could be useful during preformulation where sufficient amounts of the drug are not always available to perform dissolution studies.

  19. Does crystallographic anisotropy prevent the conventional treatment of aqueous mineral reactivity? A case study based on K-feldspar dissolution kinetics

    Science.gov (United States)

    Pollet-Villard, Marion; Daval, Damien; Ackerer, Philippe; Saldi, Giuseppe D.; Wild, Bastien; Knauss, Kevin G.; Fritz, Bertrand

    2016-10-01

    Which conceptual framework should be preferred to develop mineral dissolution rate laws, and how the aqueous mineral reactivity should be measured? For over 30 years, the classical strategy to model solid dissolution over large space and time scales has relied on so-called kinetic rate laws derived from powder dissolution experiments. In the present study, we provide detailed investigations of the dissolution kinetics of K-feldspar as a function of surface orientation and chemical affinity which question the commonplace belief that elementary mechanisms and resulting rate laws can be retrieved from conventional powder dissolution experiments. Nanometer-scale surface measurements evidenced that K-feldspar dissolution is an anisotropic process, where the face-specific dissolution rate satisfactorily agrees with the periodic bond chain (PBC) theory. The chemical affinity of the reaction was shown to impact differently the various faces of a single crystal, controlling the spontaneous nucleation of etch pits which, in turn, drive the dissolution process. These results were used to develop a simple numerical model which revealed that single crystal dissolution rates vary with reaction progress. Overall, these results cast doubt on the conventional protocol which is used to measure mineral dissolution rates and develop kinetic rate laws, because mineral reactivity is intimately related to the morphology of dissolving crystals, which remains totally uncontrolled in powder dissolution experiments. Beyond offering an interpretive framework to understand the large discrepancies consistently reported between sources and across space scales, the recognition of the anisotropy of crystal reactivity challenges the classical approach for modeling dissolution and weathering, and may be drawn upon to develop alternative treatments of aqueous mineral reactivity.

  20. Swift heavy ion irradiation of Pt nanocrystals: I. shape transformation and dissolution

    Energy Technology Data Exchange (ETDEWEB)

    Giulian, R.; Araujo, L.L.; Kluth, P.; Sprouster, D.J.; Schnohr, C.S.; Byrne, A.P.; Ridgway, M.C. (ANU)

    2014-09-24

    We report on the effects of swift heavy ion irradiation of embedded Pt nanocrystals (NCs), which change from spheres to prolate spheroids to rods upon irradiation. Using a broad range of ion irradiation energies and NC mean sizes we demonstrate that the elongation and dissolution processes are energy and size dependent, attaining comparable levels of shape transformation and dissolution upon a given energy density deposited in the matrix. The NC shape transformation remains operative despite discontinuous ion tracks in the matrix and exhibits a constant threshold size for elongation. In contrast, for ion irradiations in which the ion tracks are continuous, the threshold size for elongation is clearly energy dependent.

  1. Blueshift of the silver plasmon band using controlled nanoparticle dissolution in aqueous solution

    DEFF Research Database (Denmark)

    Mogensen, Klaus Bo; Kneipp, Katrin

    2014-01-01

    In this work, we report the size-dependent blue shift of the silver nanoparticle plasmon band in aqueous solution by means of UV/VIS spectroscopy. An oxidative dissolution scheme allows a gradual decrease in the particle sizes by controlled oxidation during recording of the optical spectra. Hence......, all sizes until complete dissolution can be obtained on the same substrate, thereby avoiding substrate-to-substrate variations and greatly increasing the size resolution. Cyanide and cysteamine are strong nucleophiles (electron pair donors) that deposits negative charge onto the NP surface. A 1/R...

  2. Bar Dissolution in Prolate Halos

    CERN Document Server

    Ideta, M; Ideta, Makoto; Hozumi, Shunsuke

    2000-01-01

    The time evolution of barred structures is examined under the influence of the external forces exerted by a spherical halo and by prolate halos. In particular, galaxy disks are placed in the plane including the major axis of prolate halos, whose configuration is often found in cosmological simulations. N-body disks in fixed external halo fields are simulated, so that bars are formed via dynamical instability. In the subsequent evolution, the bars in prolate halos dissolve gradually with time, while the bar pattern in a spherical halo remains almost unchanged to the end of the simulation. The decay times of the bars suggest that they can be destroyed in a time smaller than a Hubble time. Our results indicate that this dissolution process could occur in real barred galaxies, if they are surrounded by massive dark prolate halos, and the configuration adopted here is not unusual from the viewpoint of galaxy formation. For a prolate halo model, an additional simulation that is restricted to two-dimensional in-plan...

  3. FACE RECOGNITION FROM FRONT-VIEW FACE

    Institute of Scientific and Technical Information of China (English)

    WuLifang; ShenLansun

    2003-01-01

    This letter presents a face normalization algorithm based on 2-D face model to rec-ognize faces with variant postures from front-view face.A 2-D face mesh model can be extracted from faces with rotation to left or right and the corresponding front-view mesh model can be estimated according to facial symmetry.Then based on the relationship between the two mesh models,the nrmalized front-view face is formed by gray level mapping.Finally,the face recognition will be finished based on Principal Component Analysis(PCA).Experiments show that better face recognition performance is achieved in this way.

  4. FACE RECOGNITION FROM FRONT-VIEW FACE

    Institute of Scientific and Technical Information of China (English)

    Wu Lifang; Shen Lansun

    2003-01-01

    This letter presents a face normalization algorithm based on 2-D face model to recognize faces with variant postures from front-view face. A 2-D face mesh model can be extracted from faces with rotation to left or right and the corresponding front-view mesh model can be estimated according to the facial symmetry. Then based on the inner relationship between the two mesh models, the normalized front-view face is formed by gray level mapping. Finally, the face recognition will be finished based on Principal Component Analysis (PCA). Experiments show that better face recognition performance is achieved in this way.

  5. In silico dissolution rates of pharmaceutical ingredients

    Science.gov (United States)

    Dogan, Berna; Schneider, Julian; Reuter, Karsten

    2016-10-01

    The correlation between in vitro dissolution rates and the efficiency of drug formulations establishes an opportunity for accelerated drug development. Using in silico methods to predict the dissolution rates bears the prospect of further efficiency gains by avoiding the actual synthesis of candidate formulations. Here, we present a computational protocol that achieves such prediction for molecular crystals at low undersaturation. The protocol exploits the classic spiral dissolution model to minimize the number of material parameters that require explicit molecular simulations. Comparison to available data for acetylsalicylic acid and alpha lactose monohydrate indicates a tunable accuracy within one order of magnitude.

  6. In vitro investigations into the formation and dissolution of infection-induced catheter encrustations.

    Science.gov (United States)

    Hesse, A; Nolde, A; Klump, B; Marklein, G; Tuschewitzki, G J

    1992-10-01

    Encrustations are the most frequent complications occurring with indwelling catheters and urine drainage systems. The conditions for bacterial infections, using synthetic urine and controlled contamination by Proteus vulgaris, were standardised by using an in vitro model. Crystal deposits on catheters were analysed by infra-red spectroscopy and scanning electron microscopy. The main components of deposits in all investigations were struvite (MgNH4PO4.6H2O) 60-70% and carbonate apatite (Ca10(PO4,CO3)6 (OH,CO3)2) 30-40%. Investigations as to the quality and quantity of encrustations confirmed the analysis. Irrigation treatment was carried out with physiological saline solution and citric acid solution (Suby G) to study and quantify the dissolution of crystal deposits. Regular irrigation with citric solution resulted in a 70% dissolution of encrustations and ensured free flow as ascertained by measuring flow rates.

  7. Exploitation of 3D face-centered cubic mesoporous silica as a carrier for a poorly water soluble drug: influence of pore size on release rate.

    Science.gov (United States)

    Zhu, Wenquan; Wan, Long; Zhang, Chen; Gao, Yikun; Zheng, Xin; Jiang, Tongying; Wang, Siling

    2014-01-01

    The purposes of the present work were to explore the potential application of 3D face-centered cubic mesoporous silica (FMS) with pore size of 16.0nm as a delivery system for poorly soluble drugs and investigate the effect of pore size on the dissolution rate. FMS with different pore sizes (16.0, 6.9 and 3.7nm) was successfully synthesized by using Pluronic block co-polymer F127 as a template and adjusting the reaction temperatures. Celecoxib (CEL), which is a BCS class II drug, was used as a model drug and loaded into FMS with different pore sizes by the solvent deposition method at a drug-silica ratio of 1:4. Characterization using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformation infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), nitrogen adsorption, X-ray diffraction (XRD), and differential scanning calorimetry (DSC) was used to systematically investigate the drug loading process. The results obtained showed that CEL was in a non-crystalline state after incorporation of CEL into the pores of FMS-15 with pore size of 16.0nm. In vitro dissolution was carried out to demonstrate the effects of FMS with different pore sizes on the release of CEL. The results obtained indicated that the dissolution rate of CEL from FMS-15 was significantly enhanced compared with pure CEL. This could be explained by supposing that CEL encountered less diffusion resistance and its crystallinity decreased due to the large pore size of 16.0nm and the nanopore channels of FMS-15. Moreover, drug loading and pore size both play an important role in enhancing the dissolution properties for the poorly water-soluble drugs. As the pore size between 3.7 and 16.0nm increased, the dissolution rate of CEL from FMS gradually increased.

  8. [Phytobezoar dissolution with Coca-Cola].

    Science.gov (United States)

    Martínez de Juan, F; Martínez-Lapiedra, C; Picazo, V

    2006-05-01

    The treatment of phytobezoar is empiric. The various therapeutic choices include dietary modifications, prokinetic drugs, gastric lavage, enzymatic dissolution, endoscopic treatment, and surgery. We present two cases of phytobezoar with successful outcome after Coca-Cola administration.

  9. A Social Psychological Perspective on Marital Dissolution

    Science.gov (United States)

    Levinger, George

    1976-01-01

    The hypothetical constructs of attraction and barrier forces, as well as contrasting alternative attractions are used to organize the research literature on the determinants of marital stability and dissolution. (Author/AM)

  10. A Social Psychological Perspective on Marital Dissolution

    Science.gov (United States)

    Levinger, George

    1976-01-01

    The hypothetical constructs of attraction and barrier forces, as well as contrasting alternative attractions are used to organize the research literature on the determinants of marital stability and dissolution. (Author/AM)

  11. Low temperature dissolution flowsheet for plutonium metal

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, W. E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Almond, P. M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Rudisill, T. S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-05-01

    The H-Canyon flowsheet used to dissolve Pu metal for PuO2 production utilizes boiling HNO3. SRNL was requested to develop a complementary dissolution flowsheet at two reduced temperature ranges. The dissolution and H2 generation rates of Pu metal were investigated using a dissolving solution at ambient temperature (20-30 °C) and for an intermediate temperature of 50-60 °C. Additionally, the testing included an investigation of the dissolution rates and characterization of the off-gas generated from the ambient temperature dissolution of carbon steel cans and the nylon bags that contain the Pu metal when charged to the dissolver.

  12. The Dissolution of Double Holliday Junctions

    DEFF Research Database (Denmark)

    Bizard, Anna H; Hickson, Ian D

    2014-01-01

    as "double Holliday junction dissolution." This reaction requires the cooperative action of a so-called "dissolvasome" comprising a Holliday junction branch migration enzyme (Sgs1/BLM RecQ helicase) and a type IA topoisomerase (Top3/TopoIIIα) in complex with its OB (oligonucleotide/oligosaccharide binding......) fold containing accessory factor (Rmi1). This review details our current knowledge of the dissolution process and the players involved in catalyzing this mechanistically complex means of completing homologous recombination reactions....

  13. Famous face recognition, face matching, and extraversion.

    Science.gov (United States)

    Lander, Karen; Poyarekar, Siddhi

    2015-01-01

    It has been previously established that extraverts who are skilled at interpersonal interaction perform significantly better than introverts on a face-specific recognition memory task. In our experiment we further investigate the relationship between extraversion and face recognition, focusing on famous face recognition and face matching. Results indicate that more extraverted individuals perform significantly better on an upright famous face recognition task and show significantly larger face inversion effects. However, our results did not find an effect of extraversion on face matching or inverted famous face recognition.

  14. Face-to-face: Perceived personal relevance amplifies face processing.

    Science.gov (United States)

    Bublatzky, Florian; Pittig, Andre; Schupp, Harald T; Alpers, Georg W

    2017-05-01

    The human face conveys emotional and social information, but it is not well understood how these two aspects influence face perception. In order to model a group situation, two faces displaying happy, neutral or angry expressions were presented. Importantly, faces were either facing the observer, or they were presented in profile view directed towards, or looking away from each other. In Experiment 1 (n = 64), face pairs were rated regarding perceived relevance, wish-to-interact, and displayed interactivity, as well as valence and arousal. All variables revealed main effects of facial expression (emotional > neutral), face orientation (facing observer > towards > away) and interactions showed that evaluation of emotional faces strongly varies with their orientation. Experiment 2 (n = 33) examined the temporal dynamics of perceptual-attentional processing of these face constellations with event-related potentials. Processing of emotional and neutral faces differed significantly in N170 amplitudes, early posterior negativity (EPN), and sustained positive potentials. Importantly, selective emotional face processing varied as a function of face orientation, indicating early emotion-specific (N170, EPN) and late threat-specific effects (LPP, sustained positivity). Taken together, perceived personal relevance to the observer-conveyed by facial expression and face direction-amplifies emotional face processing within triadic group situations. © The Author (2017). Published by Oxford University Press.

  15. Anodic dissolution of gold in alkaline solutions containing thiourea, thiosulfate and sulfite ions

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Gold dissolves electrochemically in alkaline solutions containing ligands to form complex ions with gold ion. Therefore, selective leaching of noble metals is expected without dissolution of base metals such as steels, aluminum alloys in scrap treatment. Gold electrodes were investigated using linear sweep voltammetry, EQCM method and potentiostatic electrolysis in alkaline solutions containing thiourea, Na2SO3 and Na2S2O3. The solution composition, electrode potential affect gold dissolution rate and current efficiency. The gold dissolved from anode electrode forms complex ions, suspension particles as compound precipitates and deposits on cathode electrode as a metal. Anodic efficiency for gold dissolution is between 10% and 22%. This is caused by the oxidation decomposition of sulfite ions and thiourea. The stability of the alkaline solution containing these elements was also estimated by capillary electrophoresis technique.

  16. Understanding fossil phytolith preservation: the role of partial dissolution in paleoecology and archaeology.

    Science.gov (United States)

    Cabanes, Dan; Shahack-Gross, Ruth

    2015-01-01

    Opaline phytoliths are important microfossils used for paleoecological and archaeological reconstructions that are primarily based on relative ratios of specific morphotypes. Recent studies have shown that phytolith assemblages are prone to post-depositional alteration involving partial dissolution, however, the manner in which partial dissolution affects morphotype composition is poorly understood. Here we show that morphotype assemblages from four different plant species subjected to controlled partial dissolution are significantly different from the original assemblages, indicating that the stability of various morphotypes differs, mainly depending on their surface area to bulk ratios. This underlying mechanism produces distorted morphotype compositions in partially dissolved phytolith assemblages, bearing vast implications for morphotype-based paleoecological and archaeological interpretation. Together with analyses of phytolith assemblages from a variety of archaeological sites, our results establish criteria by which well-preserved phytolith assemblages can be selected for accurate paleoecological and archaeological reconstructions.

  17. Understanding fossil phytolith preservation: the role of partial dissolution in paleoecology and archaeology.

    Directory of Open Access Journals (Sweden)

    Dan Cabanes

    Full Text Available Opaline phytoliths are important microfossils used for paleoecological and archaeological reconstructions that are primarily based on relative ratios of specific morphotypes. Recent studies have shown that phytolith assemblages are prone to post-depositional alteration involving partial dissolution, however, the manner in which partial dissolution affects morphotype composition is poorly understood. Here we show that morphotype assemblages from four different plant species subjected to controlled partial dissolution are significantly different from the original assemblages, indicating that the stability of various morphotypes differs, mainly depending on their surface area to bulk ratios. This underlying mechanism produces distorted morphotype compositions in partially dissolved phytolith assemblages, bearing vast implications for morphotype-based paleoecological and archaeological interpretation. Together with analyses of phytolith assemblages from a variety of archaeological sites, our results establish criteria by which well-preserved phytolith assemblages can be selected for accurate paleoecological and archaeological reconstructions.

  18. A formulation for dissolution in inhomogeneous temperature field

    CERN Document Server

    Fukagawa, Hiroki

    2014-01-01

    We propose equations governing the dissolution in inhomogeneous temperature field in terms of the variational principle. The derived equations clarify that the interface energy between solute and solvent has a significant effect on the process of the dissolution. The interface energy restrains the dissolution, and the moving interface involves the heat of dissolution.

  19. AN UPDATED REVIEW ON TECHNICAL ADVANCES TO ENHANCE DISSOLUTION RATE OF HYDROPHOBIC DRUGS

    Directory of Open Access Journals (Sweden)

    Anjan K. Mahapatra

    2012-10-01

    Full Text Available The dissolution behavior of drugs continues to be one of the challenging aspects in formulation development. The advent of combinatorial chemistry and high throughput screening increased the number of hydrophobic compounds significantly. The Biopharmaceutical classification scheme (BCS takes into account three major factors: solubility, intestinal permeability, and dissolution rate and all the three govern the rate and extent of oral absorption and hence bioavailability. Especially for BCS Class II substances the bioavailability of a poorly soluble drug may be enhanced by increasing the solubility and dissolution rate of it in the gastro-intestinal fluids. Drug substances whose highest dose is soluble in less than 250 ml of water over a range of pH from 1.0 to 7.5 are considered as highly soluble. In contrast, the drug compounds with solubility below 1mg mL-1 face significant dissolution or bioavailability problems. With the introduction of advanced technologies it could be possible to overcome the problems. The article provides an overview on the theoretical definitions and technical approaches broadly covering technologies and hydrophilic carriers or excipients used. Further part of the manuscript is committed to the formulation, analytical methods for the characterization of samples, dissolution or release kinetics and model fittings.

  20. DISSOLUTION OF FISSILE MATERIALS CONTAINING TANTALUM METAL

    Energy Technology Data Exchange (ETDEWEB)

    Rudisill, T; Mark Crowder, M; Michael Bronikowski, M

    2007-05-29

    The dissolution of composite materials containing plutonium (Pu) and tantalum (Ta) metals is currently performed in Phase I of the HB-Line facility. The conditions for the present flowsheet are the dissolution of 500 g of Pu metal in the 15 L dissolver using a 4 M nitric acid (HNO{sub 3}) solution containing 0.2 M potassium fluoride (KF) at 95 C for 4-6 h.[1] The Ta metal, which is essentially insoluble in HNO{sub 3}/fluoride solutions, is rinsed with process water to remove residual acid, and then burned to destroy classified information. During the initial dissolution campaign, the total mass of Pu and Ta in the dissolver charge was limited to nominally 300 g. The reduced amount of Pu in the dissolver charge coupled with significant evaporation of solution during processing of several dissolver charges resulted in the precipitation of a fluoride salt contain Pu. Dissolution of the salt required the addition of aluminum nitrate (Al(NO{sub 3}){sub 3}) and a subsequent undesired 4 h heating cycle. As a result of this issue, HB-Line Engineering requested the Savannah River National Laboratory (SRNL) to optimize the dissolution flowsheet to reduce the cycle time, reduce the risk of precipitating solids, and obtain hydrogen (H{sub 2}) generation data at lower fluoride concentrations.[2] Using samples of the Pu/Ta composite material, we performed three experiments to demonstrate the dissolution of the Pu metal using HNO{sub 3} solutions containing 0.15 and 0.175 M KF. When 0.15 M KF was used in the dissolving solution, 95.5% of the Pu in the sample dissolved in approximately 6 h. The undissolved material included a small amount of Pu metal and plutonium oxide (PuO{sub 2}) solids. Complete dissolution of the metal would have likely occurred if the dissolution time had been extended. This assumption is based on the steady increase in the Pu concentration observed during the last several hours of the experiment. We attribute the formation of PuO{sub 2} to the complexation

  1. Spray coating as a powerful technique in preparation of solid dispersions with enhanced desloratadine dissolution rate.

    Science.gov (United States)

    Kolašinac, Nemanja; Kachrimanis, Kyriakos; Djuriš, Jelena; Homšek, Irena; Grujić, Branka; Ibrić, Svetlana

    2013-07-01

    Solid dispersion systems have been widely used to enhance dissolution rate and oral bioavailability of poorly water-soluble drugs. However, the formulation process development and scale-up present a number of difficulties which has greatly limited their commercial applications. In this study, solid dispersions (SDs) of desloratadine (DSL) with povidone (PVP) and crospovidone (cPVP) were prepared by spray coating technique. The process involved the spray application of 96% ethanol solution of DSL and PVP/cPVP, and subsequent deposition of the coprecipitates onto microcrystalline cellulose pellets during drying by air flow in a mini spray coater. The results from the present study demonstrated that the spray coating process is efficient in preparing SDs with enhanced drug dissolution rate and it is highly efficient in organic solvent removal. Both PVP and cPVP greatly improved drug dissolution rate by SDs, with PVP showing better solubilization capability. Very fast drug dissolution rate is achieved from SDs containing PVP regardless of differences in K grade. SD with smaller particles of cPVP have higher drug dissolution rate in comparison to the cPVP with larger particles. Results from physical state characterization indicate that DSL in SDs exist in the amorphous (high free-energy) state which is probably stabilized by PVP/cPVP. After 6-month accelerated stability study, DSL remains amorphous, while PVP and cPVP act as anti-plasticizing agents, offering efficient steric hindrance for nucleation and crystal growth.

  2. Constant composition dissolution of mixed phases. II. Selective dissolution of calcium phosphates.

    Science.gov (United States)

    Tang, Ruikang; Hass, Michael; Wu, Wenju; Gulde, Stacey; Nancollas, George H

    2003-04-15

    Characterization of the dissolution kinetics of individual synthetic and biological calcium phosphates is of considerable importance since these phases often coexist in biological minerals. The constant composition method has been used to study the dissolution kinetics of a series of synthetic calcium phosphates, brushite (DCPD), beta-tricalcium phosphate (TCP), octacalcium phosphate (OCP), hydroxyapatite (HAP), and carbonated apatite (CAP) in the presence and absence of citric acid, as a function of pH and thermodynamic driving force. While citric acid markedly accelerates the dissolution of TCP, HAP dissolution is significantly inhibited. Moreover, this additive has almost no influence on the dissolution of DCPD, OCP, and CAP. Dual constant composition dissolution studies of mixed calcium phosphates in the presence of citric acid have also been made. Another factor, pH, also plays an important role in the dissolution of these calcium phosphates. In suspensions of calcium phosphate mixtures, specific phases can be selectively dissolved by changing experimental parameters such as pH and the presence of rate modifiers. This result has important applications for the dissolution control of dental hard tissues such as dentin, enamel, and calculus.

  3. Can the dissolution rates of individual minerals be used to describe whole rock dissolution?

    Science.gov (United States)

    Critelli, Teresa; Marini, Luigi; Schott, Jacques; Mavromatis, Vasileios; Apollaro, Carmine; Rinder, Thomas; De Rosa, Rosanna; Oelkers, Eric H.

    2014-05-01

    There have been an exhaustive number of laboratory studies determining the dissolution rates of individual minerals, but few have focused on the dissolution rates of minerals in multi-mineralic rocks. As a result, geochemical modeling of the temporal evolution of water-rock interaction is generally based on the assumption that the dissolution rate of minerals within a rock is equal to that measured in the laboratory on individual minerals. To verify this hypothesis, we have determined experimentally the dissolution rates of a well characterized metabasalt rock (Apollaro et al., 2011; Bloise et al., 2012) from the Mt. Reventino area (Southern Italy) at 25°C in mixed flow reactors. From these experiments and rock modal analysis we have deduced the dissolution rates of the minerals present in the rock (actinolite, albite, chlorite, epidote, and phengite). The major observation of this effort include: (i) only small differences in the dissolution rates of the individual minerals were observed; these rates are close to the whole-rock dissolution rate and (ii) the dissolution rates of albite and chlorite are in close agreement with laboratory rates obtained from individual mineral dissolution experiments, whereas those of actinolite, phengite, and epidote are not consistent with those reported in literature by 1-2 orders of magnitude. These results demonstrate that the dissolution rate of a given mineral in a multi-phase rock can be affected by the presence of the other minerals. Rock dissolution kinetics are likely constrained by the dissolution rates of the more abundant, lesser reactive mineral or minerals in the rock. These unreactive minerals can prevent the dissolution of the more rapidly dissolving mineral grains by keeping them out of contact with the aqueous phase. This implies that the overall weathering rate of rocks cannot be modelled from the measured dissolution rates of its individual minerals. If confirmed through further studies, this conclusion may

  4. Crystal modifications and dissolution rate of piroxicam.

    Science.gov (United States)

    Lyn, Lim Yee; Sze, Huan Wen; Rajendran, Adhiyaman; Adinarayana, Gorajana; Dua, Kamal; Garg, Sanjay

    2011-12-01

    Piroxicam is a nonsteroidal anti-inflammatory drug with low aqueous solubility which exhibits polymorphism. The present study was carried out to develop polymorphs of piroxicam with enhanced solubility and dissolution rate by the crystal modification technique using different solvent mixtures prepared with PEG 4000 and PVP K30. Physicochemical characteristics of the modified crystal forms of piroxicam were investigated by X-ray powder diffractometry, FT-IR spectrophotometry and differential scanning calorimetry. Dissolution and solubility profiles of each modified crystal form were studied and compared with pure piroxicam. Solvent evaporation method (method I) produced both needle and cubic shaped crystals. Slow crystallization from ethanol with addition of PEG 4000 or PVP K30 at room temperature (method II) produced cubic crystal forms. Needle forms produced by method I improved dissolution but not solubility. Cubic crystals produced by method I had a dissolution profile similar to that of untreated piroxicam but showed better solubility than untreated piroxicam. Cubic shaped crystals produced by method II showed improved dissolution, without a significant change in solubility. Based on the XRPD results, modified piroxicam crystals obtained by method I from acetone/benzene were cube shaped, which correlates well with the FTIR spectrum; modified needle forms obtained from ethanol/methanol and ethanol/acetone showed a slight shift of FTIR peak that may be attributed to differences in the internal structure or conformation.

  5. Research on Dissolution in the Process of Stalgmite Forming%洞穴石笋形成过程中的溶蚀作用研究

    Institute of Scientific and Technical Information of China (English)

    张会领; 姜光辉; 林玉石; 殷建军; 覃嘉铭; 张美良; 张强; 韦丽丽; 朱晓燕

    2012-01-01

    本文通过洞穴石笋沉积过程的野外观察和剖面研究分析了洞穴石笋形成过程中的溶蚀作用.依据溶蚀的原理,本文把溶蚀作用分为物理溶蚀、化学溶蚀和生物溶蚀三种类型.野外观测和石笋剖面研究表明溶蚀作用是一类普遍存在的现象.在野外,物理—化学溶蚀表现为石笋顶部的滴蚀坑穴,生物溶蚀形成披覆于石笋表面的风化壳.在剖面上,物理—化学溶蚀表现为沉积纹层的中断、沿生长轴的充填构造和孔洞,生物溶蚀则形成剖面上风化壳层.%Based on field survey and lab analysis, we emphasized the dissolution in the process of stalagmite depositing. According to mechanism of dissolution, dissolution can be sorted into three types; physical dissolution, chemical dissolution and biological dissolution. With the study of field observations and stalagmite longitudinal profiles from South China, it shows that dissolution is ubiquitous phenomena which runs through the speleothem forming process. In the field, physical dissolution and chemical dissolution lead to errosion pits on the top of stalagmites. Biological dissolution forms crusts of weathering that wrap around stalagmites. In the longitudinal profiles , physics-chemistry dissolution forms discontinued sedimentary lamina, calcium carbonate filling formation and tiny voids. Biological dissolution shapes weathering crust laminae.

  6. Criticality safety in high explosives dissolution

    Energy Technology Data Exchange (ETDEWEB)

    Troyer, S.D.

    1997-06-01

    In 1992, an incident occurred at the Pantex Plant in which the cladding around a fissile material component (pit) cracked during dismantlement of the high explosives portion of a nuclear weapon. Although the event did not result in any significant contamination or personnel exposures, concerns about the incident led to the conclusion that the current dismantlement process was unacceptable. Options considered for redesign, dissolution tooling design considerations, dissolution tooling design features, and the analysis of the new dissolution tooling are summarized. The final tooling design developed incorporated a number of safety features and provides a simple, self-contained, low-maintenance method of high explosives removal for nuclear explosive dismantlement. Analyses demonstrate that the tooling design will remain subcritical under normal, abnormal, and credible accident scenarios. 1 fig.

  7. In vitro investigation on cinnabar dissolution

    Institute of Scientific and Technical Information of China (English)

    ZENG Kewu; WANG Qi; YANG Xiaoda; WANG Kui

    2007-01-01

    To study the effects of different chemical factors in the gastrointestinal tract, I.e. pH, proteins, amino acids,ionic strength and Na2S, on the dissolution of cinnabar. The content of the total mercury in various dissolutions of cinnabar was analyzed by UV/VIS Spectrophotometer. Laser Particle Size Analyzer measured the particle distributionsin the dissolution of cinnabar. The chemical species of dis-solved substance of cinnabar in the presence of Na2S were determined using ESI-MS. The results indicate that the solu-bility of cinnabar could be increased significantly in the pres-ence ofNa2S/S0, and strong acidic pH, respectively. While theinfluence of thiol amino acid on promoting dissolutionremains relatively low. Cinnabar did not dissolve in the form of nanoparticle. It is postulated that cinnabar could be dissolved in the gastrointestinal tract in various forms of sulfur-containing mercury complexes.

  8. Modeling of Dissolution Effects on Waterflooding

    DEFF Research Database (Denmark)

    Alexeev, Artem; Shapiro, Alexander; Thomsen, Kaj

    2015-01-01

    Physico-chemical interactions between the fluid and reservoir rock due to the presence of active components in the injected brine produce changes within the reservoir and can significantly impact the fluid flow. We have developed a 1D numerical model for waterflooding accounting for dissolution...... and precipitation of the components. Extending previous studies, we consider an arbitrary chemical non-equilibrium reaction-induced dissolution. We account for different individual volumes that a component has when precipitated or dissolved. This volume non-additivity also affects the pressure and the flow rate...... reaction rates) may exhibit rapid increase of porosity and permeability near the inlet probably indicating a formation of high permeable channels (wormholes). Water saturation in the zone of dissolution increases due to an increase in the bulk volume accessible for the injected fluid. Volumetric non...

  9. DISSOLUTION OF IRRADIATED MURR FUEL ASSEMBLIES

    Energy Technology Data Exchange (ETDEWEB)

    Kyser, E.

    2010-06-17

    A literature survey on the dissolution of spent nuclear fuel from the University of Missouri Research Reactor (MURR) has been performed. This survey encompassed both internal and external literature sources for the dissolution of aluminum-clad uranium alloy fuels. The most limiting aspect of dissolution in the current facility configuration involves issues related to the control of the flammability of the off-gas from this process. The primary conclusion of this work is that based on past dissolution of this fuel in H-Canyon, four bundles of this fuel (initial charge) may be safely dissolved in a nitric acid flowsheet catalyzed with 0.002 M mercuric nitrate using a 40 scfm purge to control off-gas flammability. The initial charge may be followed by a second charge of up to five bundles to the same dissolver batch depending on volume and concentration constraints. The safety of this flowsheet relies on composite lower flammability limits (LFL) estimated from prior literature, pilot-scale work on the dissolution of site fuels, and the proposed processing flowsheet. Equipment modifications or improved LFL data offer the potential for improved processing rates. The fuel charging sequence, as well as the acid and catalyst concentrations, will control the dissolution rate during the initial portion of the cycle. These parameters directly impact the hydrogen and off-gas generation and, along with the purge flowrate determine the number of bundles that may be charged. The calculation approach within provides Engineering a means to determine optimal charging patterns. Downstream processing of this material should be similar to that of recent processing of site fuels requiring only minor adjustments of the existing flowsheet parameters.

  10. Saltcake dissolution FY 1998 status report

    Energy Technology Data Exchange (ETDEWEB)

    HERTING, D.L.

    1999-05-18

    A laboratory scouting study was completed on the dissolution characteristics of Hanford waste from three single-shell waste tanks: 241-BY-102, 241-BY-106, and 241-B-106. Gross dissolution behavior (percent undissolved solids as a function of dilution) is explained in terms of characteristics of individual salts in the waste. The percentage of the sodium inventory retrievable from the tanks by dissolving saltcake at reasonable dilution levels is estimated at 86% of the total sodium for tank BY-102, 98% for BY-106, and 79% for B-106.

  11. Microbial dissolution of silicate materials. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Schwartzman, D. [Howard Univ., Washington, DC (United States). Dept. of Biology

    1996-03-26

    The objective of this research was to better understand the role of selected thermophilic bacteria in the colonization and dissolution of silicate minerals, with potential applications to the HDR Project. The demonstration of enhanced dissolution from microbial effects is critically dependent on providing a mineral bait within a media deficient in the critical nutrient found in the mineral (e.g., Fe). Reproducible experimental conditions in batch experiments require agitation to expose mineral powders, as well as nearly similar initial conditions for both inoculated cultures and controls. It is difficult, but not impossible to ensure reproducible conditions with microbes favoring filamentous growth habits.

  12. Retention and clearance of inhaled ceramic fibres in rat lungs and development of a dissolution model.

    OpenAIRE

    Yamato, H; Hori, H.; Tanaka, I; Higashi, T; Morimoto, Y.; Kido, M

    1994-01-01

    Male Wistar rats were exposed to aluminium silicate ceramic fibres by inhalation to study pulmonary deposition, clearance, and dissolution of the fibres. Rats were killed at one day, one month, three months, and six months after the termination of exposure. After exposure, fibres greater than 50 microns in length were seen with a scanning electron microscope in the alveolar region of the lung. Fibres were recovered from the lungs with a low temperature ashing technique and their number, diame...

  13. Behavior of iodine in the dissolution of spent nuclear fuels

    Energy Technology Data Exchange (ETDEWEB)

    Sakurai, Tsutomu; Komatsu, Kazunori; Takahashi, A. [Japan Atomic Energy Research Institute, Ibaraki-ken (Japan)

    1997-08-01

    The results of laboratory-scale experiments concerning the behavior of iodine in the dissolution of spent nuclear fuels, which were carried out at the Japan Atomic Energy Research Institute, are summarized. Based on previous and new experimental results, the difference in quantity of residual iodine in the fuel solution between laboratory-scale experiments and reprocessing plants is discussed, Iodine in spent fuels is converted to the following four states: (1) oxidation into I{sub 2} by nitric acid, (2) oxidation into I{sub 2} by nitrous acid generated in the dissolution, (3) formation of a colloid of insoluble iodides such as AgI and PdI{sub 2}, and (4) deposition on insoluble residue. Nitrous acid controls the amount of colloid formed. As a result, up to 10% of iodine in spent fuels is retained in the fuel solution, up to 3% is deposited on insoluble residue, and the balance volatilizes to the off-gas, Contrary to earlier belief, when the dissolution is carried out in 3 to 4 M HNO{sub 3} at 100{degrees}C, the main iodine species in a fuel solution is a colloid, not iodate, Immediately after its formation, the colloid is unstable and decomposes partially in the hot nitric acid solution through the following reaction: AgI(s) + 2HNO{sub 3}(aq) = {1/2}I{sub 2}(aq) + AgNO{sub 3}(aq) + NO{sub 2}(g) + H{sub 2}O(1). For high concentrations of gaseous iodine, I{sub 2}(g), and NO{sub 2}, this reaction is reversed towards formation of the colloid (AgI). Since these concentrations are high near the liquid surface of a plant-scale dissolver, there is a possibility that the colloid is formed there through this reversal, Simulations performed in laboratory-scale experiments demonstrated this reversal, This phenomenon can be one reason the quantity of residual iodine in spent fuels is higher in reprocessing plants than in laboratory-scale experiments. 17 refs., 5 figs., 3 tabs.

  14. European cinema: face to face with Hollywood

    NARCIS (Netherlands)

    T. Elsaesser

    2005-01-01

    In the face of renewed competition from Hollywood since the early 1980s and the challenges posed to Europe's national cinemas by the fall of the Wall in 1989, independent filmmaking in Europe has begun to re-invent itself. European Cinema: Face to Face with Hollywood re-assesses the different debate

  15. Mapping Teacher-Faces

    Science.gov (United States)

    Thompson, Greg; Cook, Ian

    2013-01-01

    This paper uses Deleuze and Guattari's concept of faciality to analyse the teacher's face. According to Deleuze and Guattari, the teacher-face is a special type of face because it is an "overcoded" face produced in specific landscapes. This paper suggests four limit-faces for teacher faciality that actualise different mixes of significance and…

  16. Efavirenz Dissolution Enhancement I: Co-Micronization

    Directory of Open Access Journals (Sweden)

    Helvécio Vinícius Antunes Rocha

    2012-12-01

    Full Text Available AIDS constitutes one of the most serious infectious diseases, representing a major public health priority. Efavirenz (EFV, one of the most widely used drugs for this pathology, belongs to the Class II of the Biopharmaceutics Classification System for drugs with very poor water solubility. To improve EFV’s dissolution profile, changes can be made to the physical properties of the drug that do not lead to any accompanying molecular modifications. Therefore, the study objective was to develop and characterize systems with efavirenz able to improve its dissolution, which were co-processed with sodium lauryl sulfate (SLS and polyvinylpyrrolidone (PVP. The technique used was co-micronization. Three different drug:excipient ratios were tested for each of the two carriers. The drug dispersion dissolution results showed significant improvement for all the co-processed samples in comparison to non-processed material and corresponding physical mixtures. The dissolution profiles obtained for dispersion with co-micronized SLS samples proved superior to those of co-micronized PVP, with the proportion (1:0.25 proving the optimal mixture. The improvements may be explained by the hypothesis that formation of a hydrophilic layer on the surface of the micronized drug increases the wettability of the system formed, corroborated by characterization results indicating no loss of crystallinity and an absence of interaction at the molecular level.

  17. Dissolution studies of synthetic soddyite and uranophane

    Energy Technology Data Exchange (ETDEWEB)

    Casas, I.; Perez, I.; Torrero, E. [Universidad Politecnica de Cataluna, Barcelona (Spain); Bruno, J.; Cera, E.; Duro, L. [QuantiSci SL, Centre d`Empreses de Noves Tecnologies, Cerdanyola del Valles (Spain)

    1997-09-01

    The dissolution of synthetically obtained soddyite and uranophane has been studied in solutions of low ionic strength. These are the likely final phases of the oxidative alternation pathway of uranium dioxide. The thermodynamic and kinetic dissolution properties of these phases have been determined at different bicarbonate concentrations. The solubilities determined in the experiments with soddyite correspond fairly well to the theoretical model calculated with a log K{sup 0}{sub s0}=3.9{+-}0.7. For uranophane, the best fitting was obtained for a log K{sup 0}{sub s0}=11.7{+-}0.6. The dissolution rate in the presence of bicarbonate gave for soddyite an average value of 6.8({+-}4.4) 10{sup -10} mol m{sup -2} s{sup -1}. For uranophane, under the same experimental conditions, the following dissolution rate equation has been derived: r{sub 0}(mol m{sup -2} s{sup -1})=10{sup -9{+-}2.}[HCO{sub 3}{sup -}]{sup 0.69{+-}0.09} {sup 2}. 16 refs, 29 figs, 7 tabs.

  18. Dissolution enhancement of chlorzoxazone using cogrinding technique

    Science.gov (United States)

    Raval, Mihir K.; Patel, Jaydeep M.; Parikh, Rajesh K.; Sheth, Navin R.

    2015-01-01

    Purpose: The aim of the present work was to improve rate of dissolution and processing parameters of BCS class II drug, chlorzoxazone using cogrinding technique in the presence of different excipients as a carrier. Materials and Methods: The drug was coground with various carriers like polyethylene glycol (PEG 4000), hydroxypropyl methylcellulose (HPMC) E50LV, polyvinylpyrrolidone (PVP)K30, Kaolin and Neusilin US2 using ball mill, where only PEG 4000 improved dissolution rate of drug by bringing amorphization in 1:3 ratio. The coground mixture after 3 and 6 h was evaluated for various analytical, physicochemical and mechanical parameters. Results: The analysis showed conversion of Chlorzoxazone from its crystalline to amorphization form upon grinding with PEG 4000. Coground mixture as well as its directly compressed tablet showed 2.5-fold increment in the dissolution rate compared with pure drug. Directly compressible tablets prepared from pure drug required a large quantity of microcrystalline cellulose (MCC) during compression. The coground mixture and formulation was found stable in nature even after storage (40°C/75% relative humidity). Conclusions: Cogrinding can be successfully utilized to improve the rate of dissolution of poorly water soluble drugs and hence bioavailability. PMID:26682195

  19. Dissolution of Gypsum from field observations

    Directory of Open Access Journals (Sweden)

    Klimchouk A.

    1996-01-01

    Full Text Available The paper reports the results of field measurements of gypsum dissolution in various countries (Ukraine, Spain, Italy and others and in different environments (river waters, precipitation, vadose zone, unconfined aquifer, perched cave lakes, ephemeral streams in caves, confined aquifer, cave air.

  20. Medical dissolution of canine struvite uroliths.

    Science.gov (United States)

    Osborne, C A; Polzin, D J; Kruger, J M; Abdullahi, S U; Leininger, J R; Griffith, D P

    1986-03-01

    Medical therapy is an effective method of canine struvite urolith dissolution. Recommendations include (1) eradication or control of urinary tract infection (if present), (2) use of calculolytic diets, and (3) administration of urease inhibitors to patients with persistent urinary tract infection caused by urease-producing microbes.

  1. Dilution physics modeling: Dissolution/precipitation chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Onishi, Y.; Reid, H.C.; Trent, D.S.

    1995-09-01

    This report documents progress made to date on integrating dilution/precipitation chemistry and new physical models into the TEMPEST thermal-hydraulics computer code. Implementation of dissolution/precipitation chemistry models is necessary for predicting nonhomogeneous, time-dependent, physical/chemical behavior of tank wastes with and without a variety of possible engineered remediation and mitigation activities. Such behavior includes chemical reactions, gas retention, solids resuspension, solids dissolution and generation, solids settling/rising, and convective motion of physical and chemical species. Thus this model development is important from the standpoint of predicting the consequences of various engineered activities, such as mitigation by dilution, retrieval, or pretreatment, that can affect safe operations. The integration of a dissolution/precipitation chemistry module allows the various phase species concentrations to enter into the physical calculations that affect the TEMPEST hydrodynamic flow calculations. The yield strength model of non-Newtonian sludge correlates yield to a power function of solids concentration. Likewise, shear stress is concentration-dependent, and the dissolution/precipitation chemistry calculations develop the species concentration evolution that produces fluid flow resistance changes. Dilution of waste with pure water, molar concentrations of sodium hydroxide, and other chemical streams can be analyzed for the reactive species changes and hydrodynamic flow characteristics.

  2. Time-Related Determinants of Marital Dissolution.

    Science.gov (United States)

    Heaton, Tim B.

    1991-01-01

    Examined temporal dimensions (timing of prior events, historical time, duration dependence, selectivity) and their impact on marital dissolution in multivariate continuous time model using data from June 1985 Current Population Survey. Results indicated that marital stability decreased over time, increased over marital duration, increased with age…

  3. Microbially mediated barite dissolution in anoxic brines

    Science.gov (United States)

    Ouyang, Bingjie; Akob, Denise M.; Dunlap, Darren S.; Renock, Devon

    2017-01-01

    Fluids injected into shale formations during hydraulic fracturing of black shale return with extraordinarily high total-dissolved-solids (TDS) and high concentrations of barium (Ba) and radium (Ra). Barite, BaSO4, has been implicated as a possible source of Ba as well as a problematic mineral scale that forms on internal well surfaces, often in close association with radiobarite, (Ba,Ra)SO4. The dissolution of barite by abiotic processes is well quantified. However, the identification of microbial communities in flowback and produced water necessitates the need to understand barite dissolution in the presence of bacteria. Therefore, we evaluated the rates and mechanisms of abiotic and microbially-mediated barite dissolution under anoxic and hypersaline conditions in the laboratory. Barite dissolution experiments were conducted with bacterial enrichment cultures established from produced water from Marcellus Shale wells located in northcentral Pennsylvania. These cultures were dominated by anaerobic halophilic bacteria from the genus Halanaerobium. Dissolved Ba was determined by ICP-OES and barite surfaces were investigated by SEM and AFM. Our results reveal that: 1) higher amounts of barium (up to ∼5 × ) are released from barite in the presence of Halanaerobium cultures compared to brine controls after 30 days of reaction, 2) etch pits that develop on the barite (001) surface in the presence of Halanaerobium exhibit a morphology that is distinct from those that form during control experiments without bacteria, 3) etch pits that develop in the presence of Halanaerobium exhibit a morphology that is similar to the morphology of etch pits formed in the presence of strong organic chelators, EDTA and DTPA, and 4) experiments using dialysis membranes to separate barite from bacteria suggest that direct contact between the two is not required in order to promote dissolution. These results suggest that Halanaerobium increase the rate of barite dissolution in anoxic and

  4. Effect of background electrolytes on gypsum dissolution

    Science.gov (United States)

    Burgos-Cara, Alejandro; Putnis, Christine; Ruiz-Agudo, Encarnacion

    2015-04-01

    Knowledge of the dissolution behaviour of gypsum (CaSO4· 2H2O) in aqueous solutions is of primary importance in many natural and technological processes (Pachon-Rodriguez and Colombani, 2007), including the weathering of rocks and gypsum karst formations, deformation of gypsum-bearing rocks, the quality of drinking water, amelioration of soil acidity, scale formation in the oil and gas industry or measurement of water motion in oceanography. Specific ions in aqueous solutions can play important but very different roles on mineral dissolution. For example, the dissolution rates and the morphology of dissolution features may be considerably modified by the presence of the foreign ions in the solution, which adsorb at the surface and hinder the detachment of the ions building the crystal. Dissolution processes in the aqueous environment are closely related to the rearrangement of water molecules around solute ions and the interaction between the solvent molecules themselves. The rearrangement of water molecules with respect to solute species has been recognized as the main kinetic barrier for crystal dissolution in many systems (Davis, 2000; De Yoreo and Dove 2004; Wasylenki et al. 2005). Current research suggest that the control that electrolytes exert on water structure is limited to the local environment surrounding the ions and is not related to long-range electric fields emanating from the ions but results from effects associated with the hydration shell(s) of the ions (Collins et al. 2007) and the ions' capacity to break or structure water (i.e. chaotropic and kosmotropic ions, respectively). These effects will ultimately affect the kinetics of crystal dissolution, and could be correlated with the water affinity of the respective background ions following a trend known as the lyotropic or Hofmeister series (Kunz et al. 2004; Dove and Craven, 2005). In situ macroscopic and Atomic Force Microscopy (AFM) flow-through dissolution experiments were conducted at a

  5. Importance of surface structure on dissolution of fluorite

    DEFF Research Database (Denmark)

    Godinho, Jose; Piazolo, Sandra; Balic Zunic, Tonci

    2014-01-01

    Dissolution rates are usually calculated as a function of surface area, which is assumed to remain constant ignoring the changes occurring on the surface during dissolution. Here we present a study of how topography of natural fluorite surfaces with different orientation changes during up to 3200 h...... of dissolution. Results are analyzed in terms of changes in surface area, surface reactivity and dissolution rates. All surfaces studied present fast changes in topography during the initial 200 h of dissolution. The controlling factors that cause the development of topography are the stability of the step edges...... forming the initial surface and its inclination to the closest stable planes, which are specific for each surface orientation. During an initial dissolution regime dissolution rates decrease significantly, even though the total surface area increases. During a second dissolution regime, some surfaces...

  6. Elimination of taphonomic bias in late Paleocene to early Eocene paleoenvironmental reconstructions by means of experimental dissolution studies on foraminifera

    Science.gov (United States)

    Nguyen, T. M. P.; Petrizzo, M. R.; Speijer, R. P.

    2009-04-01

    Fossil foraminifera provide a prime tool in marine paleoenvironmental reconstructions. Their shells record physico-chemical conditions in the water column and on the sea floor, which through geochemical analyses are being employed in paleoclimatic, paleoceanographic and stratigraphic researches. Furthermore, the quantitative and taxonomic compositions of foraminiferal assemblages provide insight into numerous aspects of depositional conditions, such as productivity, temperature, etc. Selective dissolution can severely alter the composition of the fossil foraminiferal assemblages. Although preferential dissolution in foraminiferal assemblages is widely recognized in modern and Quaternary deep-sea sediments, the phenomenon is often neglected in studies dealing with Paleogene sediments. Uncritical use of foraminiferal assemblages, without a serious assessment of their preservation may lead to distorted paleoenvironmental reconstructions. We carried out dissolution experiments on upper Paleocene to lower Eocene foraminiferal assemblages and selected taxa from the central Pacific (Allison Guyot and Shatsky Rise) and the Tethys (Dababiya, Egypt) in order to reveal the effects of differential dissolution on the composition of foraminiferal assemblages. Dissolution phenomena are a recurrent problem of upper Paleocene to lower Eocene foraminiferal assemblages, especially in connection with the Paleocene-Eocene Thermal Maximum (PETM). In some sequences severe dissolution is easily recognized by the absence of calcareous foraminifera in clay beds. However, less severe dissolution is rarely documented as such, although there are various more subtle indications, such as increased fragmentation and depressed absolute abundance and P/B ratios. Our study aims to investigate the effects of differential dissolution on the quantitative composition of planktonic and benthic foraminiferal assemblages. More specifically, we aim at developing objective criteria for the evaluation of

  7. Direct Imaging of Nanoscale Dissolution of Dicalcium Phosphate Dihydrate by an Organic Ligand: Concentration Matters

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Lihong [Huazhong Agricultural University, China; Zhang, Wenjun [Huazhong Agricultural University, China; Lu, Jianwei [Huazhong Agricultural University, China; Stack, Andrew G [ORNL; Wang, Lijun [Huazhong Agricultural University, China

    2013-01-01

    Unraveling the kinetics and mechanisms of sparingly soluble calcium orthophosphate (Ca!P) dissolution in the presence of organic acids at microscopic levels is important for an improved understanding in determining the effectiveness of organic acids present in most rhizosphere environments. Herein, we use in situ atomic force microscopy (AFM) coupled with a fluid reaction cell to image dissolution on the (010) face of brushite, CaHPO4 2H2O, in citrate- bearing solutions over a broad concentration range. We directly measure the dependence of molecular step retreat rate on citrate concentration at various pH values and ionic strengths, relevant to soil solution conditions. We find that low concentrations of citrate(10!100 M)inducedareductioninstepretreatratesalongboththe[10 0]Ccand[101] Ccdirections.However,at higher concentrations (exceeding 0.1 mM), this inhibitory effect was reversed with step retreat speeds increasing rapidly. These results demonstrate that the concentration-dependent modulation of nanoscale Ca!P phase dissolution by citrate may be applied to analyze the controversial role of organic acids in enhancing Ca!P mineral dissolution in a more complex rhizosphere environment. These in situ observations may contribute to resolving the previously unrecognized interactions of root exudates (low molecular weight organic acids) and sparingly soluble Ca!P minerals.

  8. Direct imaging of nanoscale dissolution of dicalcium phosphate dihydrate by an organic ligand: concentration matters.

    Science.gov (United States)

    Qin, Lihong; Zhang, Wenjun; Lu, Jianwei; Stack, Andrew G; Wang, Lijun

    2013-01-01

    Unraveling the kinetics and mechanisms of sparingly soluble calcium orthophosphate (Ca-P) dissolution in the presence of organic acids at microscopic levels is important for an improved understanding in determining the effectiveness of organic acids present in most rhizosphere environments. Herein, we use in situ atomic force microscopy (AFM) coupled with a fluid reaction cell to image dissolution on the (010) face of brushite, CaHPO4 · 2H2O, in citrate-bearing solutions over a broad concentration range. We directly measure the dependence of molecular step retreat rate on citrate concentration at various pH values and ionic strengths, relevant to soil solution conditions. We find that low concentrations of citrate (10-100 μM) induced a reduction in step retreat rates along both the [100]Cc and [101]Cc directions. However, at higher concentrations (exceeding 0.1 mM), this inhibitory effect was reversed with step retreat speeds increasing rapidly. These results demonstrate that the concentration-dependent modulation of nanoscale Ca-P phase dissolution by citrate may be applied to analyze the controversial role of organic acids in enhancing Ca-P mineral dissolution in a more complex rhizosphere environment. These in situ observations may contribute to resolving the previously unrecognized interactions of root exudates (low molecular weight organic acids) and sparingly soluble Ca-P minerals.

  9. Characterization and Dissolution Kinetics Testing of Radioactive H-3 Calcine

    Energy Technology Data Exchange (ETDEWEB)

    Garn, Troy Gerry; Batcheller, Thomas Aquinas

    2002-09-01

    Characterization and dissolution kinetics testing were performed with Idaho radioactive H-3 calcine. Calcine dissolution is the key front-end unit operation for the Separations Alternative identified in the Idaho High Level Waste Draft EIS. The impact of the extent of dissolution on the feasibility of Separations must be clearly quantified.

  10. RELATIVE DISSOLUTION RATES OF RADIOACTIVE MATERIALS USED AT AWE.

    Science.gov (United States)

    Miller, T J; Bingham, D; Cockerill, R; Waldren, S; Moth, N

    2016-09-01

    A simple in vitro dissolution test was used to provide a semi-quantitative comparison of the relative dissolution rates of samples of radioactive materials used at Atomic Weapons Establishment in a lung fluid surrogate (Ringer's solution). A wide range of dissolution rates were observed for aged legacy actinides, freshly produced actinide alloys and actinides from waste management operations.

  11. 21 CFR 343.90 - Dissolution and drug release testing.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 5 2010-04-01 2010-04-01 false Dissolution and drug release testing. 343.90...-COUNTER HUMAN USE Testing Procedures § 343.90 Dissolution and drug release testing. (a) [Reserved] (b) Aspirin capsules. Aspirin capsules must meet the dissolution standard for aspirin capsules as contained in...

  12. Examining Two Types of Best Friendship Dissolution during Early Adolescence

    Science.gov (United States)

    Bowker, Julie C.

    2011-01-01

    This study examined young adolescents' experiences with best friendship dissolution. Participants were 77 sixth-grade students (M age = 11.63 years, SD = 0.36; 11.00-12.69 age range) who reported on past experiences with (1) "complete dissolutions" (when friendship ties are completely severed), and (2) "downgrade dissolutions"…

  13. 20 CFR 404.1219 - Dissolution of political subdivision.

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Dissolution of political subdivision. 404... Agreements Is Obtained and Continues § 404.1219 Dissolution of political subdivision. If a political... satisfactory evidence of its dissolution or nonexistence. The evidence must establish that the entity is not...

  14. 10 CFR 960.4-2-6 - Dissolution.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Dissolution. 960.4-2-6 Section 960.4-2-6 Energy DEPARTMENT... REPOSITORY Postclosure Guidelines § 960.4-2-6 Dissolution. (a) Qualifying condition. The site shall be located such that any subsurface rock dissolution will not be likely to lead to radionuclide releases...

  15. 12 CFR 710.8 - Certificate of dissolution and liquidation.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 6 2010-01-01 2010-01-01 false Certificate of dissolution and liquidation. 710... UNIONS VOLUNTARY LIQUIDATION § 710.8 Certificate of dissolution and liquidation. Within 120 days after the final distribution of assets to members is started, a duly executed Certificate of Dissolution and...

  16. 32 CFR 202.10 - RAB adjournment and dissolution.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 2 2010-07-01 2010-07-01 false RAB adjournment and dissolution. 202.10 Section... dissolution. (a) RAB adjournment—(1) Requirements for RAB adjournment. An Installation Commander may adjourn a... Commander decides to adjourn the RAB. (b) RAB dissolution—(1) Requirements for RAB dissolution. An...

  17. Multiparametric study of thorium oxide dissolution in aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Simonnet, Marie; Barre, Nicole; Drot, Romuald; Le Naour, Claire; Sladkov, Vladimir; Delpech, Sylvie [Universite Paris-Saclay, CNRS-IN2P3, Orsay (France). Institut de Physique Nucleaire

    2016-07-01

    Thorium oxide is poorly soluble: unlike uranium oxide, concentrated nitric acid medium is not sufficient to get quantitative dissolution. Addition of small amounts of fluoride is required to achieve thorium oxide total dissolution. The effect of several parameters on thorium oxide dissolution in order to optimize the dissolution conditions is reported in this paper. Thus the influence of solid characteristics, dissolution method, temperature and composition of dissolution medium on ThO{sub 2} dissolution rate has been studied. No complexing agents tested other than fluoride allows total dissolution. Beyond a given HF concentration a decrease of the dissolution rate is observed due to the formation of a precipitate at the solid/solution interface. It was demonstrated by XPS measurements that this precipitate is constituted of thorium fluoride (ThF{sub 4}) formed during the ThO{sub 2} dissolution. The low concentration of HF required to achieve a total dissolution and the activation energy value measured tends to show a catalytic effect of HF on the dissolution process.

  18. Geochemistry and sedimentary environments Deep-water carbonate dissolution in the northern South China Sea during Marine Isotope Stage 3

    Institute of Scientific and Technical Information of China (English)

    Na Wang; Bao-Qi Huang; He Li

    2016-01-01

    The production, transportation, deposition, and dissolution of carbonate profoundly form part of the global carbon cycle and affect the amount and distribution of dissolved inorganic carbon (DIC) and alkalinity (ALK), which drive atmospheric CO2 changes during glacial/interglacial cycles. These processes may provide significant clues for better understanding of the mechanisms that control the global climate system. In this study, we calculate and analyze the foraminiferal dissolution index (FDX) and the fragmentation ratios of planktonic foraminifera for the 60-25 ka B.P. time-span, based on samples from Core 17924 and ODP Site 1144 in the northeastern South China Sea (SCS), so as to reconstruct the deep-water car-bonate dissolution during Marine Isotope Stage 3 (MIS 3). Our analysis shows that the dissolution of carbonate increases gradually in Core 17924, whereas it remains stable at ODP Site 1144. This difference is caused by the deep-sea carbonate ion concentration﹙[CO32-]﹚that affected the dissolution in Core 17924 where the depth of 3440 m is below the saturation horizon. However, the depth of ODP Site 1144 is 2037 m, which is above the lysocline where the water is always saturated with calcium carbonate; the dissolution is therefore less dependent of chemical changes of the seawater. The combined effect of the productivity and the deep-water chemical evolution may decrease deep-water [CO32-] and accelerate car-bonate dissolution. The fall of the sea-level increased the input of DIC and ALK to the deep ocean and deepened the carbonate saturation depth, which caused an increase of the deep-water [CO32-]. The elevated [CO32-] partially neutralized the reduced [CO32-] contributed by remineralization of organic matter and slowdown of thermohaline. These consequently are the fundamental reasons for the difference in dissolution rate between these two sites.

  19. Montmorillonite Dissolution in Simulated Lung Fluids

    Science.gov (United States)

    Schmidt, M.; Wendlandt, R. F.

    2008-12-01

    Because lung fluids" first interaction is with the surface of inhaled grains, the surface properties of inhaled mineral dusts may have a generally mitigating effect on cytotoxicity and carcinogenicity. Wendlandt et al. (Appl. Geochem. 22, 2007) investigated the surface properties of respirable-sized quartz grains in bentonites and recognized pervasive montmorillonite surface coatings on silica grains. The purpose of this study was to determine the dissolution rate and biodurability of montmorillonite in simulated lung fluids and to assess its potential to mitigate silica cytotoxicity. Modified batch reaction experiments were conducted on purified and size fractionated calcic (SAz-2; 0.4-5 μm) and sodic (DC-2; 0.4-2 μm) montmorillonites for 120 to 160 days of reaction time at 37°C in both simulated extracellular lung fluid (Lu) and simulated lysosomal fluid (Ly). Modified batch experiments simulated a flow-through setup and minimized sample handling difficulties. Reacted Lu and Ly fluid was analyzed for Mg, Al, and Si on an ICP-OE spectrometer. Steady state dissolution was reached 90-100 days after the start of the experiment and maintained for 40-60 days. Measured montmorillonite dissolution rates based on BET surface areas and Si steady state release range from 4.1x10-15 mol/m2/s at the slowest to 1.0x10-14 mol/m2/s at the fastest with relative uncertainties of less than 10%. Samples reacting in Ly (pH = 4.55) dissolved faster than those in Lu (pH = 7.40), and DC-2 dissolved faster than SAz-2. The measured range of biodurabilities was 1,300 to 3,400 years for a 1 μm grain assuming a spherical volume and a molar volume equal to that of illite. The difference in salinities of the two fluids was too slight to draw conclusions about the relationship of ionic strength to dissolution rate. Results indicate that montmorillonite dissolution is incongruent and edge controlled. Dissolution rates for DC- 2 and SAz-2 clays were comparable to those reported in the

  20. [Ultrastructure of diatom Synedra acus subsp. radians as revealed by transmission electron microscopy after mild silica dissolution].

    Science.gov (United States)

    Bedoshvili, E D; Likhoshvaĭ, E V; Grachev, M A

    2007-01-01

    A diatom Synedra acus subsp. radians (Kütz.) Skabitsch. has been studied by transmission electron microscopy. Examination of ultrathin sections demonstrated that silica dissolution in ammonium fluoride pH 5 under mild conditions leaves the key ultrastructural elements intact. The ultrastructure and arrangement of the cell organelles was studied during ontogeny. Silicalemma-surrounded silica deposition vesicles (SDVs) with maturating daughter valves and forming girdle bands have been identified. This method of SDV visualization offers considerable advantages over the standard approach without silica dissolution.

  1. Exploitation of 3D face-centered cubic mesoporous silica as a carrier for a poorly water soluble drug: Influence of pore size on release rate

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Wenquan; Wan, Long; Zhang, Chen; Gao, Yikun; Zheng, Xin; Jiang, Tongying; Wang, Siling, E-mail: silingwang@syphu.edu.cn

    2014-01-01

    The purposes of the present work were to explore the potential application of 3D face-centered cubic mesoporous silica (FMS) with pore size of 16.0 nm as a delivery system for poorly soluble drugs and investigate the effect of pore size on the dissolution rate. FMS with different pore sizes (16.0, 6.9 and 3.7 nm) was successfully synthesized by using Pluronic block co-polymer F127 as a template and adjusting the reaction temperatures. Celecoxib (CEL), which is a BCS class II drug, was used as a model drug and loaded into FMS with different pore sizes by the solvent deposition method at a drug–silica ratio of 1:4. Characterization using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformation infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), nitrogen adsorption, X-ray diffraction (XRD), and differential scanning calorimetry (DSC) was used to systematically investigate the drug loading process. The results obtained showed that CEL was in a non-crystalline state after incorporation of CEL into the pores of FMS-15 with pore size of 16.0 nm. In vitro dissolution was carried out to demonstrate the effects of FMS with different pore sizes on the release of CEL. The results obtained indicated that the dissolution rate of CEL from FMS-15 was significantly enhanced compared with pure CEL. This could be explained by supposing that CEL encountered less diffusion resistance and its crystallinity decreased due to the large pore size of 16.0 nm and the nanopore channels of FMS-15. Moreover, drug loading and pore size both play an important role in enhancing the dissolution properties for the poorly water-soluble drugs. As the pore size between 3.7 and 16.0 nm increased, the dissolution rate of CEL from FMS gradually increased. - Highlights: • Exploitation of 3D cubic mesoporous silica (16 nm) as a carrier was completed. • The release rate of CEL increased on increasing the pore size of carriers. • The crystallinity

  2. Dissolution of Hematite Nanoparticle Aggregates: Influence of Primary Particle Size, Dissolution Mechanism, and Solution pH

    NARCIS (Netherlands)

    Lanzl, C.A.; Baltrusaitis, Jonas; Cwiertny, D.M.

    2012-01-01

    The size-dependent dissolution of nanoscale hematite (8 and 40 nm α-Fe2O3) was examined across a broad range of pH (pH 1–7) and mechanisms including proton- and ligand- (oxalate-) promoted dissolution and dark (ascorbic acid) and photochemical (oxalate) reductive dissolution. Empirical relationships

  3. Face-Lift

    Science.gov (United States)

    Tests and Procedures Face-lift By Mayo Clinic Staff A face-lift (rhytidectomy) is a cosmetic surgical procedure to improve the look of your face and neck. During a face-lift, facial soft tissues are lifted, excess skin is ...

  4. Formation, dissolution and properties of surface nanobubbles

    CERN Document Server

    Che, Zhizhao

    2016-01-01

    Surface nanobubbles are stable gaseous phases in liquids that form onto solid substrates. While their existence has been confirmed, there are many open questions related to their formation and dissolution processes along with their structure and properties, which are difficult to investigate experimentally. To address these issues, we carried out molecular dynamics simulations based on atomistic force-fields for systems comprised of water, air (N2 and O2), and a Highly Oriented Pyrolytic Graphite (HOPG) substrate. Our results provide insights into the formation/dissolution mechanisms of nanobubbles and estimates for their density, contact angle and surface tension. We found that the formation of nanobubbles is driven by an initial nucleation process of air molecules and the subsequent coalescence of the formed air clusters. The clusters form favorably on the substrate, which provides an enhanced stability to the clusters. In contrast, nanobubbles formed in the bulk move either randomly to the substrate and sp...

  5. Medical dissolution of feline struvite urocystoliths.

    Science.gov (United States)

    Osborne, C A; Lulich, J P; Kruger, J M; Polzin, D J; Johnston, G R; Kroll, R A

    1990-04-01

    The efficacy of a diet designed to facilitate dissolution of feline magnesium ammonium phosphate (struvite) uroliths was evaluated in 30 cases of urolithiasis, sterile struvite uroliths dissolved in a mean of 36 days after initiation of dietary treatment. In 5 cases of urolithiasis, struvite urocystoliths associated with urease-negative bacterial urinary tract infection dissolved in a mean of 23 days after initiation of dietary and antimicrobial treatment. In 3 cases of urolithiasis, struvite urocystoliths associated with urease-positive staphylococcal urinary tract infection dissolved in a mean of 79 days after initiation of dietary and antimicrobial treatment. Dissolution of uroliths in cats fed the treatment diet was associated with concomitant remission of dysuria, hematuria, and pyuria, and reduction in urine pH and struvite crystalluria. In one case, a urocystolith composed of 100% ammonium urate, and in another case, a urolith composed of 60% calcium phosphate, 20% calcium oxalate, and 20% magnesium ammonium phosphate did not dissolve.

  6. DISSOLUTION OF ZIRCONIUM AND ALLOYS THEREFOR

    Science.gov (United States)

    Swanson, J.L.

    1961-07-11

    The dissolution of zirconium cladding in a water solution of ammonium fluoride and ammonium nitrate is described. The method finds particular utility in processing spent fuel elements for nuclear reactors. The zirconium cladding is first dissolved in a water solution of ammonium fluoride and ammonium nitrate; insoluble uranium and plutonium fiuorides formed by attack of the solvent on the fuel materiai of the fuel element are then separated from the solution, and the fuel materiai is dissolved in another solution.

  7. Primary dissolution therapy of struvite calculi.

    Science.gov (United States)

    Dretler, S P; Pfister, R C

    1984-05-01

    Percutaneous nephrostomy and hemiacidrin were used as primary treatment of magnesium ammonium phosphate calculi in 32 surgical candidates. Of 28 patients who actually received hemiacidrin 24 (85 per cent) had successful treatment (no surgery necessary), including 19 (68 per cent) who had total stone dissolution. There were no significant complications. Patients have been followed for 3 months to 7 years. Percutaneous nephrostomy with hemiacidrin infusion is another possible treatment in the growing alternatives available for patients with urinary struvite calculi.

  8. FORMULATION STRATEGY FOR DISSOLUTION ENHANCEMENT OF SIMVASTATIN

    OpenAIRE

    Neha Parmar et al

    2012-01-01

    The present work aim was “Formulation Strategy for Dissolution Enhancement of Simvastatin”. Simvastatin is lipid lowering drug which is known as HMG CoA reductase. The objective of this study was to increase the solubility of poorly water soluble drug, namely simvastatin, by the formation of solid dispersion and complex and also using the microwave induction technique on these formations. For solid dispersion method dispersion carrier used were poloxamer 407 and gelucire 44/14. The fusion met...

  9. Aggregation, sedimentation, dissolution and bioavailability of ...

    Science.gov (United States)

    To understand their fate and transport in estuarine systems, the aggregation, sedimentation, and dissolution of CdSe quantum dots (QDs) in seawater were investigated. Hydrodynamic size increased from 40 to 60 nm to >1 mm within 1 h in seawater, and the aggregates were highly polydispersed. Their sedimentation rates in seawater were measured to be 4–10 mm/day. Humic acid (HA), further increased their size and polydispersity, and slowed sedimentation. Light increased their dissolution and release of dissolved Cd. The ZnS shell also slowed release of Cd ions. With sufficient light, HA increased the dissolution of QDs, while with low light, HA alone did not change their dissolution. The benthic zone in estuarine systems is the most probable long-term destination of QDs due to aggregation and sedimentation. The bioavailability of was evaluated using the mysid Americamysis bahia. The 7-day LC50s of particulate and dissolved QDs were 290 and 23 μg (total Cd)/L, respectively. For mysids, the acute toxicity appears to be from Cd ions; however, research on the effects of QDs should be conducted with other organisms where QDs may be lodged in critical tissues such as gills or filtering apparatus and Cd ions may be released and delivered directly to those tissues. Because of their increasing use and value to society, cadmium-based quantum dots (QDs) will inevitably find their way into marine systems. In an effort to understand the fate and transport of CdSe QDs in estuar

  10. Dissolution of Marriage According to Canon Law

    Directory of Open Access Journals (Sweden)

    MSc. Sulejman Ahmedi

    2013-12-01

    Full Text Available In the Canon law, dissolution of marriage is not allowed since it was considered sacred and as such cannot break until the two spouses are alive, except only if one of the spouses passes away. But throughout history we find cases when allowed dissolution of the marriage and causes specific conditions set by the church. Thus, according to the Old Testament, if, a man married to a woman, didn’t like something about his wife, should write a request for divorce and allow her to leave his home. Meanwhile according to the New Testament records, divorce is prohibited. Although most Protestants continue to espouse the view that marriage was sacred and as such should not be divorced, from those who had supported the idea of granting the divorce. One of them was Luther, who in his remarks before his preachers said: "In my opinion, the issue of divorce belongs to the law, are not they to whom called for regulation of parental relationships, why not have they the authority to regulate the relations between spouses". Protestant churches allow the dissolution of marriage: a Because of adultery by the wife; allowed by Jesus, b Unjustified abandonment of the marital community; c If there were other reasons: if one spouse refuses to have sexual marriage, if the husband abuses his wife     repeatedly and without cause, severe illness of one spouse.

  11. Dissolution of ordered precipitates under ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Camus, E.; Bourdeau, F.; Abromeit, C.; Wanderka, N.; Wollenberger, H. [Hahn-Meitner-Institut Berlin GmbH (Germany)

    1995-09-01

    The stability of the ordered {gamma}{prime} precipitates under 300-keV Ni{sup +} irradiation was investigated between room temperature and 623 K. The two competing mechanisms of destabilization by cascade producing irradiation, i.e. disordering and dissolution of the {gamma}{prime} precipitates in Nimonic PE16 alloy, has been studied separately by electron microscopy and field-ion microscopy with atom probe. At high temperatures, the precipitates are stable. At intermediate temperatures, the precipitates dissolve by ballistic mixing into the matrix, but the interface is restored by the radiation-enhanced atomic jumps. The order in the precipitates remains stable. At low temperatures, the precipitates are dissolved by atomic mixing. The dissolution proceeds in a diffusional manner with a diffusion coefficient normalized by the displacement rate D/K = 0.75 nm{sup 2}dpa{sup {minus}1}. The precipitates become disordered by a fluence of 0.1 dpa, whereas precipitate dissolution needs much higher fluences.

  12. Do organic ligands affect calcite dissolution rates?

    Science.gov (United States)

    Oelkers, Eric H.; Golubev, Sergey V.; Pokrovsky, Oleg S.; Bénézeth, Pascale

    2011-04-01

    Steady state Iceland-spar calcite dissolution rates were measured at 25 °C in aqueous solutions containing 0.1 M NaCl and up to 0.05 M dissolved bicarbonate at pH from 7.9 to 9.1 in the presence of 13 distinct dissolved organic ligands in mixed-flow reactors. The organic ligands considered in this study include those most likely to be present in either (1) aquifers at the conditions pertinent to CO 2 sequestration or (2) soil/early diagenetic environments: acetate, phthalate, citrate, EDTA 4-, succinate, D-glucosaminate, L-glutamate, D-gluconate, 2,4-dihydroxybenzoate, 3,4-dihydroxybenzoate, fumarate, malonate, and gallate. Results show that the presence of extract, humic acid, pectin, and gum xanthan. In no case did the presence of <100 ppm of these organics change calcite dissolution rates by more than a factor of 2.5. Results obtained in this study suggest that the presence of aqueous organic anions negligibly affects calcite forward dissolution rates in most natural environments. Some effect on calcite reactivity may be observed, however, by the presence of organic anions if they change substantially the chemical affinity of the fluid with respect to calcite.

  13. Anomalous dissolution of metals and chemical corrosion

    Directory of Open Access Journals (Sweden)

    DRAGUTIN M. DRAZIC

    2005-03-01

    Full Text Available An overview is given of the anomalous behavior of some metals, in particular Fe and Cr, in acidic aqueous solutions during anodic dissolution. The anomaly is recognizable by the fact that during anodic dissolutionmore material dissolves than would be expected from the Faraday law with the use of the expected valence of the formed ions. Mechanical disintegration, gas bubble blocking, hydrogen embrittlement, passive layer cracking and other possible reasons for such behavior have been discussed. It was shown, as suggested by Kolotyrkin and coworkers, that the reason can be, also, the chemical reaction in which H2O molecules with the metal form metal ions and gaseous H2 in a potential independent process. It occurs simultaneously with the electrochemical corrosion process, but the electrochemical process controls the corrosion potential. On the example of Cr in acid solution itwas shown that the reason for the anomalous behavior is dominantly chemical dissolution, which is considerably faster than the electrochemical corrosion, and that the increasing temperature favors chemical reaction, while the other possible reasons for the anomalous behavior are of negligible effect. This effect is much smaller in the case of Fe, but exists. The possible role of the chemical dissolution reacton and hydrogen evolution during pitting of steels and Al and stress corrosion cracking or corrosion fatigue are discussed.

  14. Results of urinary dissolution therapy for radiolucent calculi

    Directory of Open Access Journals (Sweden)

    Sinha Maneesh

    2013-01-01

    Full Text Available Purpose In this paper we present our experience with dissolution therapy of radiolucent calculi. Materials and Methods This was a retrospective analysis of patients who were offered urinary dissolution therapy between January 2010 and June 2011. Patients were treated with tablets containing potassium citrate and magnesium oxide. Partial dissolution was defined as at least a 50% reduction in stone size. Patients with complete or partial dissolution were classified in the successful dissolution group. Patients with no change, inadequate reduction, increase in stone size and those unable to tolerate alkali therapy were classified as failures. Patient sex, stenting before alkalinization, stone size, urine pH at presentation and serum uric acid levels were analyzed using Fisher t-test for an association with successful dissolution. Results Out of 67, 48 patients reported for follow up. 10 (15% had complete dissolution and 13 (19% had partial dissolution. Alkalinization was unsuccessful in achieving dissolution in 25 (37%. Stenting before alkalinization, patient weight ( 75kg and serum uric acid levels (≤ 6 vs. > 6 were the only factors to significantly affected dissolution rates (p = 0.039, p 0.035, p 0.01 respectively. CONCLUSIONS A policy of offering dissolution therapy to patients with radiolucent calculi had a successful outcome in 34% of patients.

  15. Monitoring Lidocaine Single-Crystal Dissolution by Ultraviolet Imaging

    DEFF Research Database (Denmark)

    Ostergaard, Jesper; Ye, Fengbin; Rantanen, Jukka

    2011-01-01

    Dissolution critically affects the bioavailability of Biopharmaceutics Classification System class 2 compounds. When unexpected dissolution behaviour occurs, detailed studies using high information content technologies are warranted. In the present study, an evaluation of real‐time ultraviolet (UV......) imaging for conducting single‐crystal dissolution studies was performed. Using lidocaine as a model compound, the aim was to develop a setup capable of monitoring and quantifying the dissolution of lidocaine into a phosphate buffer, pH 7.4, under stagnant conditions. A single crystal of lidocaine...... was placed in the quartz dissolution cell and UV imaging was performed at 254 nm. Spatially and temporally resolved mapping of lidocaine concentration during the dissolution process was achieved from the recorded images. UV imaging facilitated the monitoring of lidocaine concentrations in the dissolution...

  16. Dissolution Model Development: Formulation Effects and Filter Complications

    DEFF Research Database (Denmark)

    Berthelsen, Ragna; Holm, Rene; Jacobsen, Jette

    2016-01-01

    This study describes various complications related to sample preparation (filtration) during development of a dissolution method intended to discriminate among different fenofibrate immediate-release formulations. Several dissolution apparatus and sample preparation techniques were tested. The flow......-through cell apparatus (USP 4) was found unfit for dissolution testing of fenofibrate MeltDose formulations due to clogging of filters and varying flow rates. A mini paddle dissolution setup produced dissolution profiles of the tested formulations that correlated well with clinical data. The work towards...... the mini paddle dissolution method demonstrates that sample preparation influenced the results. The investigations show that excipients from the formulations directly affected the drug–filter interaction, thereby affecting the dissolution profiles and the ability to predict the in vivo data...

  17. Dissolution energetics and its strain dependence of transition metal alloying elements in tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Wen-Li; Zhou, Hong-Bo, E-mail: hbzhou@buaa.edu.cn; Jin, Shuo; Zhang, Ying; Lu, Guang-Hong, E-mail: LGH@buaa.edu.cn

    2015-01-15

    We have systematically investigated the dissolution energetics of all 3d–5d transition metal alloying elements (AEs) in tungsten (W) using a first-principles method. It is found that Ti is the easiest one to dissolve with the solution energy of −0.81 eV in the intrinsic bulk W, while La is the most difficult one with the solution energy as large as 3.91 eV. The d-electrons play a determining role in the dissolution of AEs in W. We have demonstrated that the solution energies of AEs is a linear monotonic function of strain. The binding energy results indicate that the interaction between AEs is repulsive for the early elements and then becomes attractive for the late elements in each series. This study provides a good reference for developing W materials as a plasma facing material.

  18. METALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    <正>20070291 Gong Ping (Northern Fujian Geological Party, Shaozou 354000) Discussion on Geological Characteristics and Control Factors of the Shimen Au-polymetallic Deposit in Zhenghe County, Fujian Province (Geology of Fujian, ISSN1001-3970, CN38-1080/P, 25(1), 2006, p.18-24, 2 illus., 2 tables, 1 ref.) Key words: gold deposits, polymetallic deposits, Fujian Province

  19. Mineral dissolution kinetics at the pore scale

    Energy Technology Data Exchange (ETDEWEB)

    Li, L.; Steefel, C.I.; Yang, L.

    2007-05-24

    Mineral dissolution rates in the field have been reported to be orders of magnitude slower than those measured in the laboratory, an unresolved discrepancy that severely limits our ability to develop scientifically defensible predictive or even interpretive models for many geochemical processes in the earth and environmental sciences. One suggestion links this discrepancy to the role of physical and chemical heterogeneities typically found in subsurface soils and aquifers in producing scale-dependent rates where concentration gradients develop. In this paper, we examine the possibility that scale-dependent mineral dissolution rates can develop even at the single pore and fracture scale, the smallest and most fundamental building block of porous media. To do so, we develop two models to analyze mineral dissolution kinetics at the single pore scale: (1) a Poiseuille Flow model that applies laboratory-measured dissolution kinetics at the pore or fracture wall and couples this to a rigorous treatment of both advective and diffusive transport, and (2) a Well-Mixed Reactor model that assumes complete mixing within the pore, while maintaining the same reactive surface area, average flow rate, and geometry as the Poiseuille Flow model. For a fracture, a 1D Plug Flow Reactor model is considered in addition to quantify the effects of longitudinal versus transverse mixing. The comparison of averaged dissolution rates under various conditions of flow, pore size, and fracture length from the three models is used as a means to quantify the extent to which concentration gradients at the single pore and fracture scale can develop and render rates scale-dependent. Three important minerals that dissolve at widely different rates, calcite, plagioclase, and iron hydroxide, are considered. The modeling indicates that rate discrepancies arise primarily where concentration gradients develop due to comparable rates of reaction and advective transport, and incomplete mixing via molecular

  20. The mathematical model of the stripping voltammetry hydrogen evolution/dissolution process on Pd layer

    Energy Technology Data Exchange (ETDEWEB)

    Skital, Piotr M. [Faculty of Chemistry, Rzeszow University of Technology, Wincentego Pola Str. 2, 35-959 Rzeszow (Poland); Sanecki, Przemyslaw T., E-mail: psanecki@prz.rzeszow.p [Faculty of Chemistry, Rzeszow University of Technology, Wincentego Pola Str. 2, 35-959 Rzeszow (Poland); Kaczmarski, Krzysztof [Faculty of Chemistry, Rzeszow University of Technology, Wincentego Pola Str. 2, 35-959 Rzeszow (Poland)

    2010-08-01

    The advanced two-plate mathematical model of electrochemical hydrogen evolution/dissolution process has been presented and discussed. The model, with Langmuir adsorption equation, has been experimentally verified by the use of the glassy carbon/Pd layer electrode system at different scan rates. The two cathodic-anodic stages of hydrogen evolution/dissolution process in 0.1 M and 0.001 M HCl solutions have been interpreted and discussed. The thickness of the layer and the way of deposition were also investigated. The fundamental kinetic problem of a change of electrode properties during electrode process as an effect of the elementary hydrogen presence in the solid electrode is presented and interpreted. The isopotential point phenomenon, an electrochemical analog of isosbestic point in absorption spectroscopy, was unexpectedly discovered as experimental effect of hydrogen adsorption and {alpha} variability.

  1. Further studies of the anodic dissolution in sodium chloride electrolyte of aluminium alloys containing tin and gallium

    Science.gov (United States)

    Nestoridi, Maria; Pletcher, Derek; Wharton, Julian A.; Wood, Robert J. K.

    As part of a programme to develop a high power density, Al/air battery with a NaCl brine electrolyte, the high rate dissolution of an aluminium alloy containing tin and gallium was investigated in a small volume cell. The objective was to define the factors that limit aluminium dissolution in condition that mimic a high power density battery. In a cell with a large ratio of aluminium alloy to electrolyte, over a range of current densities the extent of dissolution was limited to ∼1000 C cm -2 of anode surface by a thick layer of loosely bound, crystalline deposit on the Al alloy anode formed by precipitation from solution. This leads to a large increase in impedance and acts as a barrier to transport of ions.

  2. Further studies of the anodic dissolution in sodium chloride electrolyte of aluminium alloys containing tin and gallium

    Energy Technology Data Exchange (ETDEWEB)

    Nestoridi, Maria; Pletcher, Derek [The School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Wharton, Julian A.; Wood, Robert J.K. [School of Engineering Sciences, The University, Southampton SO17 1BJ (United Kingdom)

    2009-09-05

    As part of a programme to develop a high power density, Al/air battery with a NaCl brine electrolyte, the high rate dissolution of an aluminium alloy containing tin and gallium was investigated in a small volume cell. The objective was to define the factors that limit aluminium dissolution in condition that mimic a high power density battery. In a cell with a large ratio of aluminium alloy to electrolyte, over a range of current densities the extent of dissolution was limited to {proportional_to}1000 C cm{sup -2} of anode surface by a thick layer of loosely bound, crystalline deposit on the Al alloy anode formed by precipitation from solution. This leads to a large increase in impedance and acts as a barrier to transport of ions. (author)

  3. Influence of dissolved oxygen on silver nanoparticle mobility and dissolution in water-saturated quartz sand

    Energy Technology Data Exchange (ETDEWEB)

    Mittelman, Anjuliee M.; Taghavy, Amir; Wang, Yonggang; Abriola, Linda M.; Pennell, Kurt D., E-mail: kurt.pennell@tufts.edu [Tufts University, Department of Civil and Environmental Engineering (United States)

    2013-07-15

    The influence of dissolved oxygen (DO) on the transport behavior and dissolution kinetics of silver nanoparticles (nAg) was explored through a combination of experimental and mathematical modeling studies. One-dimensional column experiments were conducted with water-saturated 40-50 mesh Ottawa sand, operated at pH 4 or 7 under three DO conditions (8.9, 2, or <0.2 mg/L). The experimental protocol consisted of a nAg deposition phase, designed to assess nanoparticle mobility as a function of DO level, followed by a dissolution phase, to evaluate the release of Ag{sup +} from retained nanoparticles. Experimental observations revealed that the mobility of nAg increased by 15 % when the DO level was reduced from 8.9 to <0.2 mg/L at pH 4, and that, once retained by the quartz sand, the fraction of nAg mass eluted as Ag{sup +} decreased from 21.6 to 13.5 to 11.3 % with decreasing oxygen level (8.9, 2, and <0.2 mg/L, respectively). In both batch and column studies, rates of nAg dissolution decreased over time, behavior attributed to aging of the nanoparticle surface due to oxidation. A hybrid Eulerian-Lagrangian nanoparticle transport model was developed and implemented to simulate the mobility of nAg, subject to DO-dependent dissolution kinetics and particle aging. Model simulations accurately captured nAg transport and dissolution as a function of pH and DO level, and demonstrate the importance of considering nanoparticle surface aging to accurately predict Ag{sup +} release over time.

  4. IVIVR in oral absorption for fenofibrate immediate release tablets using dissolution and dissolution permeation methods.

    Science.gov (United States)

    Buch, P; Holm, P; Thomassen, J Q; Scherer, D; Kataoka, M; Yamashita, S; Langguth, P

    2010-10-01

    In a previous study it has been demonstrated that a dissolution/permeation (D/P) system can discriminate between different immediate release fenofibrate formulations. The fractions permeated were correlated with fenofibrate's in vivo exposure in rats following p.o. administration. In the present study more detailed investigations are presented using data from six fenofibrate tablets tested in vivo in humans. In these pharmacokinetic studies no significant differences between formulations in AUC but in Cmax were found. Differences between the Cmax values were not explained by the dissolution characteristics of the tablets but were rationalized on the basis of micellar entrapment and diminished mobility of the active ingredient by surfactants in the formulations. This was demonstrated by a permeation system using dialysis membranes. Thus a permeation step in addition to dissolution measurement may significantly improve the establishment of an IVIV relationship.

  5. Influence of pH and temperature on alunite dissolution rates and products

    Science.gov (United States)

    Acero, Patricia; Hudson-Edwards, Karen

    2015-04-01

    , leading to dissolved Al/K ratios between 0.5 and 2.5. This depletion of Al in the solution is especially clear for the experiments at pH 4.5-4.8 and 8 and it is consistent with the results of elemental quantifications of the same proportions in the reacted alunite surfaces using X-ray Photoelectron Spectroscopy (XPS). REFERENCES Flaten, T.P. (2001): Aluminium as a risk factor in Alzheimzer's disease, with emphasis on drinking water. Brain Research Bulletin 55: 187-196. Nordstrom, D.K. (2011): Hydrogeochemical processes governing the origin, transport and fate of major and trace elements from mine wastes and mineralized rock to surface waters. Applied Geochemistry 26: 1777-1791. Prietzel, J., & Hirsch, C. (1998). Extractability and dissolution kinetics of pure and soil-added synthesized aluminium hydroxy sulphate minerals. European journal of soil science, 49(4), 669-681. Swayze, G.A., Ehlmann, B.L., Milliken, R.E., Poulet, F., Wray, J.J., Rye, R.O., Clark, R.N., Desborough, G.A., Crowley, J.K., Gondet, B., Mustard, J.F., Seelos, K.D. and Murchie, S.L., 2008. Discovery of the Acid-Sulfate Mineral Alunite in Terra Sirenum, Mars, Using MRO CRISM: Possible Evidence for Acid-Saline Lacustrine Deposits?, American Geophysical Union, Fall Meeting 2008, abstract #P44A-04. Welch, S. A., Kirste, D., Christy, A. G., Beavis, F. R., & Beavis, S. G. (2008): Jarosite dissolution II'Reaction kinetics, stoichiometry and acid flux. Chemical Geology, 254(1), 73-86.

  6. Dissolution rate enhancement of piroxicam by ordered mixing.

    Science.gov (United States)

    Saharan, Vikas Anand; Choudhury, Pratim Kumar

    2012-07-01

    Micronized piroxicam was mixed with lactose, mannitol, sorbitol, maltitol and sodium chloride to produce ordered mixture in a glass vial by manual hand shaking method. The effect of excipients, surfactant, superdisintegrant, drug concentration and carrier particle size on dissolution rate was investigated. Dissolution rate studies of the prepared ordered mixtures revealed that all water soluble excipients increased the dissolution rate of piroxicam when compared to the dissolution rate of piroxicam or its suspension. Ordered mixture formulation PLF4, consisting of lactose as water soluble excipient, SSG (8% w/s) and SLS (1% w/w), released piroxcam at a very fast rate so much so that about 90% of the composition had passed into solution within 2 min. The order of the dissolution rate enhancement for ordered mixtures of various water soluble excipients was: lactose > mannitol > maltitol > sorbitol > sodium chloride. Carrier granules of size 355-710 µm were most effective in increasing the dissolution rate of drug from ordered mixtures. Decreasing the carrier particle size reduced drug dissolution from ordered mixtures. The dissolution rate of ordered mixtures consisting of 1-5% w/w piroxicam was superior to dissolution rate of piroxicam suspension. The dissolution data fitting and the resulting regression parameters indicated Hixson Crowell, cube root law, as the best fit to drug release data of ordered mixtures.

  7. Deep water dissolution in Marine Isotope Stage 3 from the northern South China Sea

    Science.gov (United States)

    Huang, B.

    2015-12-01

    The production, transport, deposition, and dissolution of carbonate profoundly implicate the global carbon cycle affect the inventory and distribution of dissolved organic carbon (DIC) and alkalinity (ALK), which drive atmospheric CO2 change on glacial-interglacial timescale. the process may provide significant clues for improved understanding of the mechanisms that control the global climate system. In this study, we calculate and analyze the foraminiferal dissolution index (FDX) and the fragmentation ratios of planktonic foraminifera over 60-25 ka based on samples from 17924 and ODP 1144 in the northeastern South China Sea (SCS) to reconstruct the deep water carbonate dissolution during Marine Isotope Stage 3 (MIS 3). Result shows that the dissolution of carbonate increases gradually at 17924 but keeps stable at ODP 1144. The changes of FDX coincidence with that of fragmentation ratios at 17924 and ODP 1144 suggest both indexes can be used as reliable dissolving proxies of planktonic foraminifera. Comparing FDX and fragmentation ratios at both sites, we find the FDX and fragmentation ratios at 17924 are higher than those at 1144, indicating that carbonate dissolution is intenser in 17924 core during MIS 3. The increasing total percentage of both N. dutertrei and G. bulloides during MIS 3 reveals the rising primary productivity that may lead to deep water [CO32-] decrease. The slow down of thermohaline circulation may increase deep water residence time and accelerate carbonate dissolution. In addition, the covering of ice caps, iron supply and increased surface-water stratification also contribute to atmosphere CO2 depletion and [CO32-] decrease in deep water. In the meanwhile, regression result from colder temperature increases the input of ALK and DIC to the deep ocean and deepens the carbonate saturation depth, which makes the deep water [CO32-] rise. In ODP Site 1144, the decrease in [CO32-] caused by more CO2 restored in deep water is equal to the increase in

  8. CaCO3 dissolution by holothurians (sea cucumber): a case study from One Tree Reef, Great Barrier Reef

    Science.gov (United States)

    Schneider, K.; Silverman, J.; Kravitz, B.; Woolsey, E.; Eriksson, H.; Schneider-Mor, A.; Barbosa, S.; Rivlin, T.; Byrne, M.; Caldeira, K.

    2012-12-01

    Holothurians (sea cucumbers) are among the largest and most important deposit feeder in coral reefs. They play a role in nutrient and CaCO3 cycling within the reef structure. As a result of their digestive process they secrete alkalinity due to CaCO3 dissolution and organic matter degradation forming CO2 and ammonium. In a survey at station DK13 on One Three Reef we found that the population density of holothurians was > 1 individual m-2. The dominant sea cucumber species Holothuria leucospilota was collected from DK13. The increase in alkalinity due to CaCO3 dissolution in aquaria incubations was measured to be 47±7 μmol kg-1 in average per individual. Combining this dissolution rate with the sea cucumbers concentrations at DK13 suggest that they may account for a dissolution rate of 34.9±17.8 mmol m-2 day-1, which is equivalent to about half of night time community dissolution measured in DK13. This indicates that in reefs where the sea cucumber population is healthy and protected from fishing they can be locally important in the CaCO3 cycle. Preliminary result suggests that the CaCO3 dissolution rates are not affected by the chemistry of the sea water they are incubated in. Measurements of the empty digestive track volume of two sea cucumbers H. atra and Stichopus herrmanni were 36 ± 4 ml and 151 ± 14 ml, respectively. Based on these measurements it is estimated that these species process 19 ± 2kg and 80 ± 7kg CaCO3 sand yr-1 per individual, respectively. The annual dissolution rates of H. atra and S. herrmanni are 6.5±1.9g and 9.6±1.4g, respectively, suggest that 0.05±0.02% and 0.1±0.02% of the CaCO3 processed through their gut annually is dissolved. During the incubations the CaCO3 dissolution was 0.07±0.01%, 0.04±0.01% and 0.21±0.05% of the fecal casts for H. atra, H. leucospilota and S. herrmanni, respectively. Our result that the primary parameter determining the CaCO3 dissolution by sea cucumber is the amount of carbonate send in their gut

  9. Iron dissolution of dust source materials during simulated acidic processing: the effect of sulfuric, acetic, and oxalic acids.

    Science.gov (United States)

    Chen, Haihan; Grassian, Vicki H

    2013-09-17

    Atmospheric organic acids potentially display different capacities in iron (Fe) mobilization from atmospheric dust compared with inorganic acids, but few measurements have been made on this comparison. We report here a laboratory investigation of Fe mobilization of coal fly ash, a representative Fe-containing anthropogenic aerosol, and Arizona test dust, a reference source material for mineral dust, in pH 2 sulfuric acid, acetic acid, and oxalic acid, respectively. The effects of pH and solar radiation on Fe dissolution have also been explored. The relative capacities of these three acids in Fe dissolution are in the order of oxalic acid > sulfuric acid > acetic acid. Oxalate forms mononuclear bidentate ligand with surface Fe and promotes Fe dissolution to the greatest extent. Photolysis of Fe-oxalate complexes further enhances Fe dissolution with the concomitant degradation of oxalate. These results suggest that ligand-promoted dissolution of Fe may play a more significant role in mobilizing Fe from atmospheric dust compared with proton-assisted processing. The role of atmospheric organic acids should be taken into account in global-biogeochemical modeling to better access dissolved atmospheric Fe deposition flux at the ocean surface.

  10. Dissolution of premarital cohabitation in Canada.

    Science.gov (United States)

    Wu, Z; Balakrishnan, T R

    1995-11-01

    The rapid increase in the number of unmarried cohabiting couples, indicated by recent evidence, is crucial to our understanding of changing marriage patterns. The levels and patterns of entry into cohabitation have been well documented over the last two decades, but little is known about the outcomes of nonmarital cohabitation. In this study we examine two competing outcomes of cohabitation relationships: union separation and legalization of the union through marriage. Our results show that the hazard rate of union dissolution is affected particularly by gender, fertility status, partner's marital status, religion, age at start of cohabitation, year cohabitation commenced, and region.

  11. Dissolution of struvite calculi by hemiacidrin solution.

    Science.gov (United States)

    Massaro, F J; Weiner, B; Sant, G R; Meares, E M

    1983-01-01

    Struvite calculi result from urinary tract infections secondary to urease-producing bacteria. To prevent recurrent infection and stone formation complete removal of struvite calculi is recommended. Two illustrative reports of patients with renal struvite calculi are presented in which 10% hemiacidrin (Renacidin) irrigation was instituted for stone dissolution. After surgical removal of the calculi a nephrostomy tube was placed in the renal pelvis. With confirmation of residual struvite calculi, 10% hemiacidrin irrigation was initiated. Urine cultures, electrolytes and nephrotomograms were performed and adverse effects monitored. Using strict aseptic technique and appropriate precautions, hemiacidrin irrigation safely dissolves struvite calculi.

  12. System and process for dissolution of solids

    Energy Technology Data Exchange (ETDEWEB)

    Liezers, Martin; Farmer, III, Orville T.

    2017-10-10

    A system and process are disclosed for dissolution of solids and "difficult-to-dissolve" solids. A solid sample may be ablated in an ablation device to generate nanoscale particles. Nanoparticles may then swept into a coupled plasma device operating at atmospheric pressure where the solid nanoparticles are atomized. The plasma exhaust may be delivered directly into an aqueous fluid to form a solution containing the atomized and dissolved solids. The composition of the resulting solution reflects the composition of the original solid sample.

  13. Match quality, new information, and marital dissolution.

    Science.gov (United States)

    Weiss, Y; Willis, R J

    1997-01-01

    "This article investigates the role of surprises in marital dissolution [in the United States]. Surprises consists of changes in the predicted earning capacity of either spouse. Data from the National Longitudinal Study of the High School Class of 1972 is used. We find that an unexpected increase in the husband's earning capacity reduces the divorce hazard, while an unexpected increase in the wife's earning capacity raises the divorce hazard. Couples sort into marriage according to characteristics that are likely to enhance the stability of the marriage. The divorce hazard is initially increasing with the duration of marriage, and the presence of children and high levels of property stabilizes the marriage."

  14. The dissolution or growth of a sphere

    Science.gov (United States)

    Shankar, N.; Wiltshire, Timothy J.; Subramanian, R. Shankar

    1984-01-01

    The problem of the dissolution or growth of an isolated stationary sphere in a large fluid body is analyzed. The motion of the boundary as well as the the resulting motion in the liquid are properly taken into account. The governing equations are solved using a recently developed technique (Subramanian and Weinberg, 1981) which employs an asymptotic expansion in time. Results for the radius of the sphere as a function of time are calculated. The range of utility of the present solution is established by comparison with a numerical solution of the governing equations obtained by the method of finite differences.

  15. Dissolution behavior of lithium compounds in ethanol

    Directory of Open Access Journals (Sweden)

    Tomohiro Furukawa

    2016-12-01

    Full Text Available In order to exchange the components which received irradiation damage during the operation at the International Fusion Materials Irradiation Facility, the adhered lithium, which is partially converted to lithium compounds such as lithium oxide and lithium hydroxide, should be removed from the components. In this study, the dissolution experiments of lithium compounds (lithium nitride, lithium hydroxide, and lithium oxide were performed in a candidate solvent, allowing the clarification of time and temperature dependence. Based on the results, a cleaning procedure for adhered lithium on the inner surface of the components was proposed.

  16. About (above) a face - a face

    OpenAIRE

    2009-01-01

    This text intents to unfold some considerations regardind the perception of the image of the Lóri’s face, from the book Uma aprendizagem ou o livro dos prazeres, published by Clarice Lispector in 1969. For that, will be studied the politicians devices who involve the apprehension of the face as a qualifying of the subject and, at the same time, its relation with the lenguage.

  17. About (above a face - a face

    Directory of Open Access Journals (Sweden)

    Diego Cervelin

    2009-07-01

    Full Text Available This text intents to unfold some considerations regardind the perception of the image of the Lóri’s face, from the book Uma aprendizagem ou o livro dos prazeres, published by Clarice Lispector in 1969. For that, will be studied the politicians devices who involve the apprehension of the face as a qualifying of the subject and, at the same time, its relation with the lenguage.

  18. Dissolution of Uranium Oxides Under Alkaline Oxidizing Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Steven C.; Peper, Shane M.; Douglas, Matthew; Ziegelgruber, Kate L.; Finn, Erin C.

    2009-11-01

    Bench scale experiments were conducted to determine the dissolution characteristics of uranium oxide powders (UO2, U3O8, and UO3) in aqueous peroxide-carbonate solutions. Experimental parameters included H2O2 concentration, carbonate counter cation (NH4+, Na+, K+, and Rb+), and pH. Results indicate the dissolution rate of UO2 in 1 M (NH4)2CO3 increases linearly with peroxide concentration ranging from 0.05 – 2 M. The three uranium oxide powders exhibited different dissolution patterns however, UO3 exhibited prompt complete dissolution. Carbonate counter cation affected the dissolution kinetics. There is minimal impact of solution pH, over the range 8.8 to 10.6, on initial dissolution rate.

  19. The mechanism of interface-coupled dissolution and precipitation during apparent non-stoichiometric mineral dissolution

    Science.gov (United States)

    Putnis, C. V.; Ruiz-Agudo, E.; Rodriguez-Navarro, C.; Putnis, A.

    2012-04-01

    Understanding the mechanism of multicomponent mineral and glass dissolution is important in a wide range of natural (such as weathering) and technological (such as glass corrosion) processes, as well as being crucial in defining rate laws for mineral reactions. Atomic force microscopy (AFM) has been used to make in situ nanoscale observations and measurements, which confirm the formation of a cation depleted layer at the mineral-solution interface during dissolution of multicomponent minerals such as wollastonite, CaSiO3 and dolomite Ca,Mg(CO3)2 in water at acidic pH. Observations combined with compositional analysis of reaction fluids as well as mineral precipitates, give clear evidence that such a layer is formed in a two step process: 1. stoichiometric dissolution of the mineral surface and; 2. subsequent precipitation of a secondary phase from a supersaturated fluid boundary layer in contact with the mineral surface. Such a mechanism presents a new paradigm that differs from the concept of preferential leaching of cations, as postulated by most currently accepted dissolution models. Furthermore, this mechanism applies to any Earth situation where aqueous fluids are in contact with minerals and so will be the controlling mechanism in processes such as metamorphism, metasomatism and element sequestration, eg., CO2 sequestration.

  20. Dissolution of struvite urinary stones. Experimental studies in vitro.

    Science.gov (United States)

    Griffith, D P; Bragin, S; Musher, D M

    1976-03-01

    Previous studies from our laboratory have shown that struvite crystals form primarily as a result of urease-induced alkalinity and supersaturation. In vitro perfusion of struvite crystals with undersaturated urine caused crystal dissolution. The investigations reported herein demonstrate complete dissolution of human struvite urinary stones during 6 weeks of perfusion in vitro with undersaturated human urine. Human hydroxyapatite stones perfused similarly underwent only slight dissolution. A glycoprotein precipitated as the stones dissolved; the pathogenic significance of the glycoprotein is unknown.

  1. Anodic dissolution of metals in ionic liquids

    Directory of Open Access Journals (Sweden)

    Andrew P. Abbott

    2015-12-01

    Full Text Available The anodic dissolution of metals is an important topic for battery design, material finishing and metal digestion. Ionic liquids are being used in all of these areas but the research on the anodic dissolution is relatively few in these media. This study investigates the behaviour of 9 metals in an ionic liquid [C4mim][Cl] and a deep eutectic solvent, Ethaline, which is a 1:2 mol ratio mixture of choline chloride and ethylene glycol. It is shown that for the majority of metals studied a quasi-passivation of the metal surface occurs, primarily due to the formation of insoluble films on the electrode surface. The behaviour of most metals is different in [C4mim][Cl] to that in Ethaline due in part to the differences in viscosity. The formation of passivating salt films can be decreased with stirring or by increasing the electrolyte temperature, thereby increasing ligand transport to the electrode surface.

  2. Bench Scale Saltcake Dissolution Test Report

    Energy Technology Data Exchange (ETDEWEB)

    BECHTOLD, D.B.; PACQUET, E.A.

    2000-12-06

    A potential scenario for retrieving saltcake from single shell tanks is the ''Rainbird{reg_sign} sprinkler'' method. Water is distributed evenly across the surface of the saltcake and allowed to percolate by gravity through the waste. The salt dissolves in the water, forming a saturated solution. The saturated liquid is removed by a saltwell pump situated near the bottom of the tank. By this method, there is never a large inventory of liquid in the tank that could pose a threat of leakage. There are many variables or factors that can influence the hydrodynamics of this retrieval process. They include saltcake porosity; saltwell pumping rate; salt dissolution chemistry; factors that could promote flow channeling (e.g. tank walls, dry wells, inclusions or discontinuities in the saltcake); method of water distribution; plug formation due to crystal formations or accumulation of insoluble solids. A brief literature search indicates that very little experimental data exist on these aspects of saltcake dissolution (Wiersma 1996, 1997). The tests reported here were planned (Herting, 2000) to provide preliminary data and information for planning future, scaled-up tests of the sprinkler method.

  3. A study on the dissolution rates of K-Cr(VI)-jarosites: kinetic analysis and implications.

    Science.gov (United States)

    Reyes, Iván A; Mireles, Ister; Patiño, Francisco; Pandiyan, Thangarasu; Flores, Mizraim U; Palacios, Elia G; Gutiérrez, Emmanuel J; Reyes, Martín

    2016-01-01

    The presence of natural and industrial jarosite type-compounds in the environment could have important implications in the mobility of potentially toxic elements such as lead, mercury, arsenic, chromium, among others. Understanding the dissolution reactions of jarosite-type compounds is notably important for an environmental assessment (for water and soil), since some of these elements could either return to the environment or work as temporary deposits of these species, thus would reduce their immediate environmental impact. This work reports the effects of temperature, pH, particle diameter and Cr(VI) content on the initial dissolution rates of K-Cr(VI)-jarosites (KFe3[(SO4)2 - X(CrO4)X](OH)6). Temperature (T) was the variable with the strongest effect, followed by pH in acid/alkaline medium (H3O(+)/OH(-)). It was found that the substitution of CrO4 (2-)in Y-site and the substitution of H3O(+) in M-site do not modify the dissolution rates. The model that describes the dissolution process is the unreacted core kinetic model, with the chemical reaction on the unreacted core surface. The dissolution in acid medium was congruent, while in alkaline media was incongruent. In both reaction media, there is a release of K(+), SO4 (2-) and CrO4 (2-) from the KFe3[(SO4)2 - X(CrO4)X](OH)6 structure, although the latter is rapidly absorbed by the solid residues of Fe(OH)3 in alkaline medium dissolutions. The dissolution of KFe3[(SO4)2 - X(CrO4)X](OH)6 exhibited good stability in a wide range of pH and T conditions corresponding to the calculated parameters of reaction order n, activation energy E A and dissolution rate constants for each kinetic stages of induction and progressive conversion. The kinetic analysis related to the reaction orders and calculated activation energies confirmed that extreme pH and T conditions are necessary to obtain considerably high dissolution rates. Extreme pH conditions (acidic or alkaline) cause the preferential release of K(+), SO4 (2

  4. Mathematical modeling of variables involved in dissolution testing.

    Science.gov (United States)

    Gao, Zongming

    2011-11-01

    Dissolution testing is an important technique used for development and quality control of solid oral dosage forms of pharmaceutical products. However, the variability associated with this technique, especially with USP apparatuses 1 and 2, is a concern for both the US Food and Drug Administration and pharmaceutical companies. Dissolution testing involves a number of variables, which can be divided into four main categories: (1) analyst, (2) dissolution apparatus, (3) testing environment, and (4) sample. Both linear and nonlinear models have been used to study dissolution profiles, and various mathematical functions have been used to model the observed data. In this study, several variables, including dissolved gases in the dissolution medium, off-center placement of the test tablet, environmental vibration, and various agitation speeds, were modeled. Mathematical models including Higuchi, Korsmeyer-Peppas, Weibull, and the Noyes-Whitney equation were employed to study the dissolution profile of 10 mg prednisone tablets (NCDA #2) using the USP paddle method. The results showed that the nonlinear models (Korsmeyer-Peppas and Weibull) accurately described the entire dissolution profile. The results also showed that dissolution variables affected dissolution rate constants differently, depending on whether the tablets disintegrated or dissolved.

  5. Frogging It: A poetic Analysis of Relationship Dissolution

    Directory of Open Access Journals (Sweden)

    Sandra L. Faulkner

    2012-10-01

    Full Text Available Often, themes in work and life intertwine; the author recognized that a cadre of poems she had written during the past several years were about relationship dissolution. The poems concerned romantic and friendship dissolution and the aspects of identity creation and loss this entails. The author presents the poems and makes an explicit connection to interpersonal relationship dissolution literature through the technique of poetic analysis. This analysis serves as an exemplar for how poetry as performative writing offers a valuable addition to interpersonal communication research through the poeticizing of relational dissolution as an everyday relational challenge.

  6. The influence of milling on the dissolution performance of simvastatin

    DEFF Research Database (Denmark)

    Zimper, Ulrike; Aaltonen, Jaakko; Krauel-Goellner, Karen

    2012-01-01

    Particle size reduction is a simple means to enhance the dissolution rate of poorly water soluble BCS-class II and IV drugs. However, the major drawback of this process is the possible introduction of process induced disorder. Drugs with different molecular arrangements may exhibit altered...... properties such as solubility and dissolution rate and, therefore, process induced solid state modifications need to be monitored. The aim of this study was two-fold: firstly, to investigate the dissolution rates of milled and unmilled simvastatin; and secondly, to screen for the main milling factors...... by XRPD), at a set optimization limit of dissolution testing...

  7. Dissolution of beryllium in artificial lung alveolar macrophage phagolysosomal fluid.

    Science.gov (United States)

    Stefaniak, Aleksandr B; Virji, M Abbas; Day, Gregory A

    2011-05-01

    Dissolution of a lung burden of poorly soluble beryllium particles is hypothesized to be necessary for development of chronic beryllium lung disease (CBD) in humans. As such, particle dissolution rate must be sufficient to activate the lung immune response and dissolution lifetime sufficient to maintain chronic inflammation for months to years to support development of disease. The purpose of this research was to investigate the hypothesis that poorly soluble beryllium compounds release ions via dissolution in lung fluid. Dissolution kinetics of 17 poorly soluble particulate beryllium materials that span extraction through ceramics machining (ores, hydroxide, metal, copper-beryllium [CuBe] fume, oxides) and three CuBe alloy reference materials (chips, solid block) were measured over 31 d using artificial lung alveolar macrophage phagolysosomal fluid (pH 4.5). Differences in beryllium-containing particle physicochemical properties translated into differences in dissolution rates and lifetimes in artificial phagolysosomal fluid. Among all materials, dissolution rate constant values ranged from 10(-5) to 10(-10)gcm(-2)d(-1) and half-times ranged from tens to thousands of days. The presence of magnesium trisilicate in some beryllium oxide materials may have slowed dissolution rates. Materials associated with elevated prevalence of CBD had faster beryllium dissolution rates [10(-7)-10(-8)gcm(-2)d(-1)] than materials not associated with elevated prevalence (p<0.05).

  8. The composite face illusion.

    Science.gov (United States)

    Murphy, Jennifer; Gray, Katie L H; Cook, Richard

    2017-04-01

    Few findings in cognitive science have proved as influential as the composite face effect. When the top half of one face is aligned with the bottom half of another, and presented upright, the resulting composite arrangement induces a compelling percept of a novel facial configuration. Findings obtained using composite face procedures have contributed significantly to our understanding of holistic face processing, the detrimental effects of face inversion, the development of face perception, and aberrant face perception in clinical populations. Composite paradigms continue to advance our knowledge of face perception, as exemplified by their recent use for investigating the perceptual mechanisms underlying dynamic face processing. However, the paradigm has been the subject of intense scrutiny, particularly over the last decade, and there is a growing sense that the composite face illusion, whilst easy to illustrate, is deceptively difficult to measure and interpret. In this review, we provide a focussed overview of the existing composite face literature, and identify six priorities for future research. Addressing these gaps in our knowledge will aid the evaluation and refinement of theoretical accounts of the illusion.

  9. Migration and union dissolution in a changing socio-economic context: The case of Russia

    Directory of Open Access Journals (Sweden)

    Hill Kulu

    2007-12-01

    Full Text Available Previous studies show that family migration is usually to the benefit of the man's professional career and that it has a negative impact on the woman's economic well-being and employment. This study extends previous research by examining the effect of family migration on union dissolution. We use the event-history data of two retrospective surveys from Russia and apply hazard regression. The analysis shows that couples who move frequently over long distances have a significantly higher risk of union dissolution than couples who do not move or move only once. Our further analysis reveals that the risk of disruption for frequent movers is high when the migrant woman has a job. Frequent migrants had a high risk of union dissolution during the Soviet period but they faced no such risk during the post-Soviet socio-economic transition. We argue that frequent moving increases union instability through a variety of mechanisms, the effect of which may vary across socio-economic contexts.

  10. Photochemical dissolution of organic matter from resuspended sediments: Impact of source and diagenetic state on photorelease

    Science.gov (United States)

    Helms, J. R.; Glinski, D. A.; Mead, R. N.; Southwell, M.; Avery, G. B., Jr.; Kieber, R. J.; Skrabal, S. A.

    2015-12-01

    Resuspended sediments exposed to simulated solar radiation release dissolved organic carbon (DOC). However, it is unclear how the provenance of sedimentary organic matter (OM) impacts this photorelease. In the first geographically extensive study of this phenomenon, twenty three size fractionated, fine grained sediments (humus and/or adsorbed humic and fulvic acids) play an important role in the photochemical dissolution of OC regardless of whether or not they are imported from upstream (i.e. terrestrial humics) or generated within the depositional or sedimentary environment (i.e. humification of algal dissolved OM).

  11. Estudio del comportamiento de los recargues multicapas de depósitos soldados de fundición blanca al cromo // Study of the hard facing weld behavior in deposits of white chromium steels.

    Directory of Open Access Journals (Sweden)

    R. Collazo-Carceller

    2009-05-01

    Full Text Available Se determina la influencia de los parámetros Energía introducida (Hi, Número de capas (Nc yAncho del depósito (Ad, en la morfología y el incremento de la resistencia al desgaste abrasivo decapas depositadas sobre acero 1020 utilizando el electrodo de fundición blanca al cromo UTPLedurit – 61. Empleando la microscopia óptica se identificaron y cuantificaron las fases presentes,analizando su efecto en el desgaste. Siendo determinante la influencia de la inclinación de lasdendritas y su posición con respecto a 90° en el incremento de la resistencia al desgaste abrasivo.Se caracterizaron los posibles mecanismos de daño superficial provocado por desgaste abrasivoempleando la microscopia electrónica de barrido. Se propusieron modelos lineales paracorrelacionar la influencia de la cantidad, tamaño, dispersión de los carburos y el ángulo deinclinación de las dendritas, en el incremento de la resistencia al desgaste.Palabras claves: morfología, desgaste abrasivo, parámetros de soldadura, dendritas, modelos.__________________________________________________________________________AbstractThe influence of different parameters in layer morphology and abrasion resistance of Fe-Cr-Celectrodes UTP Ledurit – 61 on steel 1020 was studied. Introduced Energy (Hi, Number of Layers(Nc, and Deposit Width (Ad were the main parameters considered. The metallographicidentification and quantification of metal phases and the determination of their effect in abrasionresistance were made with optical microscopy. The abrasive wear test characterized by scanningelectron microscopy, defines a possible mechanism of surface damage. It was found that the angleformed between a normal line to the surface and the dendrite inclination is directly related withthe increment of wear resistance. Lineal models that correlate wear resistance with quantity, size,and carbide dispersion and dendrite angle inclination were also developed.Key words: morphology, abrasive

  12. Reductive dissolution of Tl(I)-jarosite by Shewanella putrefaciens: providing new insights into Tl biogeochemistry.

    Science.gov (United States)

    Smeaton, Christina M; Walshe, Gillian E; Fryer, Brian J; Weisener, Christopher G

    2012-10-16

    Thallium (Tl) is emerging as a metal of concern in countries such as China due to its release during the natural weathering of Tl-bearing ore deposits and mining activities. Despite the high toxicity of Tl, few studies have examined the reductive dissolution of Tl mineral phases by microbial populations. In this study we examined the dissolution of synthetic Tl(I)-jarosite, (H(3)O)(0.29)Tl(0.71)Fe(2.74)(SO(4))(2)(OH)(5.22)(H(2)O)(0.78), by Shewanella putrefaciens CN32 using batch experiments under anaerobic circumneutral conditions. Fe(II) concentrations were measured over time and showed Fe(II) production (4.6 mM) in inoculated samples by 893 h not seen in mineral and dead cell controls. Release of aqueous Tl was enhanced in inoculated samples whereby maximum concentrations in inoculated and cell-free samples reached 3.2 and 2.1 mM, respectively, by termination of the experiment. Complementary batch Tl/S. putrefaciens sorption experiments were conducted under experimentally relevant pH (5 and 6.3) at a Tl concentration of 35 μM and did not show significant Tl accumulation by either live or dead cells. Therefore, in contrast to many metals such as Pb and Cd, S. putrefaciens does not represent a sink for Tl in the environment and Tl is readily released from Tl-jarosite during both abiotic and biotic dissolution.

  13. Effectively suppressing dissolution of manganese from spinel lithium manganate via a nanoscale surface-doping approach

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Jun [Argonne National Lab. (ANL), Argonne, IL (United States). Chemical Sciences and Engineering Division; Tsinghua Univ., Beijing (China). Key Lab. of Organic Optoelectronics and Molecular Engineering, Dept. of Chemistry; Zhan, Chun [Argonne National Lab. (ANL), Argonne, IL (United States). Chemical Sciences and Engineering Division; Wu, Tianpin [Argonne National Lab. (ANL), Argonne, IL (United States). X-Ray Science Division; Wen, Jianguo [Argonne National Lab. (ANL), Argonne, IL (United States). Electron Microscopy Center; Lei, Yu [Univ. of Alabama, Huntsville, AL (United States). Dept. of Chemical and Materials Engineering; Kropf, A. Jeremy [Argonne National Lab. (ANL), Argonne, IL (United States). Chemical Sciences and Engineering Division; Wu, Huiming [Argonne National Lab. (ANL), Argonne, IL (United States). Chemical Sciences and Engineering Division; Miller, Dean J. [Argonne National Lab. (ANL), Argonne, IL (United States). Electron Microscopy Center; Elam, Jeffrey W. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy System Division; Sun, Yang-Kook [Hanyang Univ., Seoule (Republic of Korea). Dept. of Energy Engineering; Qiu, Xinping [Tsinghua Univ., Beijing (China). Key Lab. of Organic Optoelectronics and Molecular Engineering, Dept. of Chemistry; Amine, Khalil [Argonne National Lab. (ANL), Argonne, IL (United States). Chemical Sciences and Engineering Division

    2014-12-16

    The capacity fade of lithium manganate-based cells is associated with the dissolution of Mn from cathode/electrolyte interface due to the disproportionation reaction of Mn(III), and the subsequent deposition of Mn(II) on the anode. Suppressing the dissolution of Mn from the cathode is critical to reducing capacity fade of LiMn2O4-based cells. Here we report a nanoscale surface-doping approach that minimizes Mn dissolution from lithium manganate. This approach exploits advantages of both bulk doping and surface-coating methods by stabilizing surface crystal structure of lithium manganate through cationic doping while maintaining bulk lithium manganate structure, and protecting bulk lithium manganate from electrolyte corrosion while maintaining ion and charge transport channels on the surface through the electrochemically active doping layer. Consequently, the surface-doped lithium manganate demonstrates enhanced electrochemical performance. This study provides encouraging evidence that surface doping could be a promising alternative to improve the cycling performance of lithium-ion batteries.

  14. Retention and clearance of inhaled ceramic fibres in rat lungs and development of a dissolution model.

    Science.gov (United States)

    Yamato, H; Hori, H; Tanaka, I; Higashi, T; Morimoto, Y; Kido, M

    1994-04-01

    Male Wistar rats were exposed to aluminium silicate ceramic fibres by inhalation to study pulmonary deposition, clearance, and dissolution of the fibres. Rats were killed at one day, one month, three months, and six months after the termination of exposure. After exposure, fibres greater than 50 microns in length were seen with a scanning electron microscope in the alveolar region of the lung. Fibres were recovered from the lungs with a low temperature ashing technique and their number, diameter, and length were measured by scanning electron microscopy. The number of fibres remaining in the lungs declined exponentially with time after exposure and their silicon content also fell. The geometric median diameter of fibres decreased linearly with time. By six months after exposure, the surface of fibres recovered from the lungs had an eroded appearance. The results suggest that ceramic fibres are physically cleared from the lung and that they show signs of dissolution. Finally, the results were used to develop a theoretical model of fibre dissolution that gives a satisfactory fit to the experimental data.

  15. The role of mass balance equations in growth mechanics illustrated in surface and volume dissolutions.

    Science.gov (United States)

    Ateshian, Gerard A

    2011-01-01

    Growth mechanics problems require the solution of mass balance equations that include supply terms and account for mass exchanges among constituents of a mixture. Though growth may often be accompanied by a variety of concomitant phenomena that increase modeling complexity, such as solid matrix deformation, evolving traction-free configurations, cell division, and active cell contraction, it is important to distinguish these accompanying phenomena from the fundamental growth process that consists of deposition or removal of mass from the solid matrix. Therefore, the objective of this study is to present a canonical problem of growth, namely, dissolution of a rigid solid matrix in a solvent. This problem illustrates a case of negative growth (loss of mass) of the solid in a mixture framework that includes three species, a solid, a solvent, and a solute, where the solute is the product of the solid dissolution. By analyzing both volumetric and surface dissolutions, the two fundamental modes of growth are investigated within the unified framework of mixture theory.

  16. Systems for Guaranteeing Bank Deposits

    OpenAIRE

    Florin Untaru

    2013-01-01

    The advent of the financial crisis and the latest event that occurred in Cyprus bring new light to how states intervene when commercial banks are facing the risk of bankruptcy. While until now institutions had a clear traditional role to protect depositors, currently there is a trend to transfer damage to companies and individuals that hold deposits.

  17. Dissolution and compaction instabilities in geomaterials

    Science.gov (United States)

    Stefanou, I.; Sulem, J.; de Sauvage, J.

    2014-12-01

    Compaction bands play an important role in reservoir engineering and geological storage. Their presence in geological formations may also provide useful information on various geological processes. Several mechanisms can be involved at different scales and may be responsible for compaction band instabilities [1]. Compaction bands can be seen as a particular instability of the governing mathematical system leading to localization of deformation [2-4]. In a saturated porous rock, the progressive mechanical damage of the solid skeleton during compaction, results in the increase of the interface area of the reactants and consequently in the acceleration of the dissolution rate of the solid phase [2,5]. Thus, the solid skeleton is degraded more rapidly (mass removal because of dissolution), the overall mechanical properties of the system diminish (contraction of the elastic domain - chemical softening), deformations increase and the solid skeleton is further damaged (intergranular fractures, debonding, breakage of the porous network etc.). The stability of this positive feedback process is investigated analytically through linear stability analysis by considering the strong chemo-poro-mechanical coupling due to chemical dissolution. The post bifurcation behavior is then studied analytically and numerically revealing the compaction band thickness and periodicity. The effect of various parameters is studied as for instance the influence of the hydraulic diffusivity on the compaction band thickness. [1] P. Baud, S. Vinciguerra, C. David, A. Cavallo, E. Walker and T. Reuschlé (2009), Pure Appl. Geophys., 166(5-7), 869-898 [2] I. Stefanou and J. Sulem (2014), JGR: Solid Earth, 119(2), 880-899. doi:10.1002/2013JB010342I [3] J.W. Rudnicki and J.R. Rice (1975), Journal of the Mechanics and Physics of Solids 23(6),: 371-394 [4] K.A. Issen and J.W. Rudnicki (2000), JGR, 105(B9), 21529. doi:10.1029/2000JB900185 [5] R. Nova, R. Castellanza and C. Tamagnini (2003), International

  18. Glass dissolution rate measurement and calculation revisited

    Energy Technology Data Exchange (ETDEWEB)

    Fournier, Maxime, E-mail: maxime.fournier@cea.fr [CEA, DEN, DTCD, SECM, F-30207, Bagnols sur Cèze (France); Ull, Aurélien; Nicoleau, Elodie [CEA, DEN, DTCD, SECM, F-30207, Bagnols sur Cèze (France); Inagaki, Yaohiro [Department of Applied Quantum Physics & Nuclear Engineering, Kyushu University, Fukuoka, 819-0395 (Japan); Odorico, Michaël [ICSM-UMR5257 CEA/CNRS/UM2/ENSCM, Site de Marcoule, BP17171, F-30207, Bagnols sur Cèze (France); Frugier, Pierre; Gin, Stéphane [CEA, DEN, DTCD, SECM, F-30207, Bagnols sur Cèze (France)

    2016-08-01

    Aqueous dissolution rate measurements of nuclear glasses are a key step in the long-term behavior study of such waste forms. These rates are routinely normalized to the glass surface area in contact with solution, and experiments are very often carried out using crushed materials. Various methods have been implemented to determine the surface area of such glass powders, leading to differing values, with the notion of the reactive surface area of crushed glass remaining vague. In this study, around forty initial dissolution rate measurements were conducted following static and flow rate (SPFT, MCFT) measurement protocols at 90 °C, pH 10. The international reference glass (ISG), in the forms of powders with different particle sizes and polished monoliths, and soda-lime glass beads were examined. Although crushed glass grains clearly cannot be assimilated with spheres, it is when using the samples geometric surface (S{sub geo}) that the rates measured on powders are closest to those found for monoliths. Overestimation of the reactive surface when using the BET model (S{sub BET}) may be due to small physical features at the atomic scale—contributing to BET surface area but not to AFM surface area. Such features are very small compared with the thickness of water ingress in glass (a few hundred nanometers) and should not be considered in rate calculations. With a S{sub BET}/S{sub geo} ratio of 2.5 ± 0.2 for ISG powders, it is shown here that rates measured on powders and normalized to S{sub geo} should be divided by 1.3 and rates normalized to S{sub BET} should be multiplied by 1.9 in order to be compared with rates measured on a monolith. The use of glass beads indicates that the geometric surface gives a good estimation of glass reactive surface if sample geometry can be precisely described. Although data clearly shows the repeatability of measurements, results must be given with a high uncertainty of approximately ±25%. - Highlights: • Initial dissolution

  19. Bacterially enhanced dissolution of meta-autunite

    Energy Technology Data Exchange (ETDEWEB)

    Smeaton, C.M.; Weisener, C.G.; Burns, P.C.; Fryer, B.J.; Fowle, D.A. (Windsor); (Kansas); (Notre)

    2008-12-15

    The release of U from the mineral meta-autunite {l_brace}Ca[(UO{sub 2})(PO{sub 2})](H{sub 2}O){sub 6}{r_brace} was evaluated using spectroscopy, aqueous geochemistry, and electron microscopy in a minimal media with the dissimilatory metal-reducing bacterium Shewanella putrefaciens 200R. The onset of anaerobic conditions resulted in the rapid release of U and phosphate to solution followed by the reprecipitation of meta-autinite. Spectroscopy measurements (XANES) indicated that the U was not released via reduction during the bacterial incubations, but instead dissolution was promoted by uptake and immobilization of P by the bacterial cells. Our results suggest that U(VI) in 'refractory' P mineral phases may be mobilized from U mill tailings and/or U disposal sites and that the nutrient status (P) of the geologic setting may be a predictor for the lability of U in these environments.

  20. Network models of dissolution of porous media

    CERN Document Server

    Budek, Agnieszka

    2012-01-01

    We investigate the chemical dissolution of porous media using a network model in which the system is represented as a series of interconnected pipes with the diameter of each segment increasing in proportion to the local reactant consumption. Moreover, the topology of the network is allowed to change dynamically during the simulation: as the diameters of the eroding pores become comparable with the interpore distances, the pores are joined together thus changing the interconnections within the network. With this model, we investigate different growth regimes in an evolving porous medium, identifying the mechanisms responsible for the emergence of specific patterns. We consider both the random and regular network and study the effect of the network geometry on the patterns. Finally, we consider practically important problem of finding an optimum flow rate that gives a maximum increase in permeability for a given amount of reactant.

  1. Solvent effects on starch dissolution and gelatinization.

    Science.gov (United States)

    Koganti, Nagamani; Mitchell, John R; Ibbett, Roger N; Foster, Tim J

    2011-08-08

    The disruption of starch granular structure during dissolution in varying concentrations of N-methyl morpholine N-oxide (NMMO) has been studied using three maize starches with varying ratios of amylose and amylopectin. Behavior in NMMO has been characterized by differential scanning calorimetry (DSC), microscopy, rapid viscosity analysis (RVA), and rheometry. Exothermic transitions were observed for the three starches in both 78 and 70% NMMO; the transition changed to an endotherm at 60 and 50% NMMO. Consistent with DSC, hot stage microscopy showed that starch granules dissolved at NMMO concentrations of 78 and 70%, whereas in 60 and 50% NMMO, gelatinization behavior similar to that found for starch in water was observed. Mechanical spectroscopy revealed the dominant viscous behavior (G″ > G') of starch at NMMO concentrations of 70 and 78% and more elastic behavior (G' > G″) at lower concentrations. Starch solutions in 78% NMMO obey the Cox-Merz rule, suggesting that the solutions are homogeneous on a molecular level.

  2. Uranium Metal Analysis via Selective Dissolution

    Energy Technology Data Exchange (ETDEWEB)

    Delegard, Calvin H.; Sinkov, Sergey I.; Schmidt, Andrew J.; Chenault, Jeffrey W.

    2008-09-10

    Uranium metal, which is present in sludge held in the Hanford Site K West Basin, can create hazardous hydrogen atmospheres during sludge handling, immobilization, or subsequent transport and storage operations by its oxidation/corrosion in water. A thorough knowledge of the uranium metal concentration in sludge therefore is essential to successful sludge management and waste process design. The goal of this work was to establish a rapid routine analytical method to determine uranium metal concentrations as low as 0.03 wt% in sludge even in the presence of up to 1000-fold higher total uranium concentrations (i.e., up to 30 wt% and more uranium) for samples to be taken during the upcoming sludge characterization campaign and in future analyses for sludge handling and processing. This report describes the experiments and results obtained in developing the selective dissolution technique to determine uranium metal concentration in K Basin sludge.

  3. Stratigraphy and dissolution of the Rustler Formation

    Energy Technology Data Exchange (ETDEWEB)

    Bachman, G.O.

    1985-04-23

    The Rustler Formation is the uppermost evaporite-bearing unit in the Permian Ochoan series in southeastern New Mexico. It rests on the Salado Formation which includes the salt beds where the mined facility for the Waste Isolation Pilot Plant (WIPP) is being constructed. An understanding of the physical stratigraphy of the Rustler Formation is pertinent to studies of the WIPP site because some portions of the Rustler are water-bearing and may provide paths for circulating waters to come into contact with, and dissolve, evaporites within the Ochoan sequence. Knowledge of the processes, magnitude, and history of evaporite dissolution in the vicinity of the WIPP site is important to an evaluation of the integrity of the site. 2 refs., 2 figs.

  4. Dissolution of bulk specimens of silicon nitride

    Science.gov (United States)

    Davis, W. F.; Merkle, E. J.

    1981-01-01

    An accurate chemical characterization of silicon nitride has become important in connection with current efforts to incorporate components of this material into advanced heat engines. However, there are problems concerning a chemical analysis of bulk silicon nitride. Current analytical methods require the pulverization of bulk specimens. A pulverization procedure making use of grinding media, on the other hand, will introduce contaminants. A description is given of a dissolution procedure which overcomes these difficulties. It has been found that up to at least 0.6 g solid pieces of various samples of hot pressed and reaction bonded silicon nitride can be decomposed in a mixture of 3 mL hydrofluoric acid and 1 mL nitric acid overnight at 150 C in a Parr bomb. High-purity silicon nitride is completely soluble in nitric acid after treatment in the bomb. Following decomposition, silicon and hydrofluoric acid are volatilized and insoluble fluorides are converted to a soluble form.

  5. Glass dissolution rate measurement and calculation revisited

    Science.gov (United States)

    Fournier, Maxime; Ull, Aurélien; Nicoleau, Elodie; Inagaki, Yaohiro; Odorico, Michaël; Frugier, Pierre; Gin, Stéphane

    2016-08-01

    Aqueous dissolution rate measurements of nuclear glasses are a key step in the long-term behavior study of such waste forms. These rates are routinely normalized to the glass surface area in contact with solution, and experiments are very often carried out using crushed materials. Various methods have been implemented to determine the surface area of such glass powders, leading to differing values, with the notion of the reactive surface area of crushed glass remaining vague. In this study, around forty initial dissolution rate measurements were conducted following static and flow rate (SPFT, MCFT) measurement protocols at 90 °C, pH 10. The international reference glass (ISG), in the forms of powders with different particle sizes and polished monoliths, and soda-lime glass beads were examined. Although crushed glass grains clearly cannot be assimilated with spheres, it is when using the samples geometric surface (Sgeo) that the rates measured on powders are closest to those found for monoliths. Overestimation of the reactive surface when using the BET model (SBET) may be due to small physical features at the atomic scale-contributing to BET surface area but not to AFM surface area. Such features are very small compared with the thickness of water ingress in glass (a few hundred nanometers) and should not be considered in rate calculations. With a SBET/Sgeo ratio of 2.5 ± 0.2 for ISG powders, it is shown here that rates measured on powders and normalized to Sgeo should be divided by 1.3 and rates normalized to SBET should be multiplied by 1.9 in order to be compared with rates measured on a monolith. The use of glass beads indicates that the geometric surface gives a good estimation of glass reactive surface if sample geometry can be precisely described. Although data clearly shows the repeatability of measurements, results must be given with a high uncertainty of approximately ±25%.

  6. Constant composition kinetics study of carbonated apatite dissolution

    Science.gov (United States)

    Tang, Ruikang; Henneman, Zachary J.; Nancollas, George H.

    2003-03-01

    The carbonated apatites (CAP) may be more suitable models for biominerals such as bone and dental hard tissues than is pure hydroxyapatite (HAP) since they have similar chemical compositions. Although they contain only a relatively small amount of carbonate, the solubility and dissolution properties are different. The solubility product of the CAP particles used in this dissolution study, 2.88×10 -112 mol 18 l -18, was significantly greater than that of HAP, 5.52×10 -118 mol 18 l -18. The kinetics of dissolution of CAP has been studied using the constant composition (CC) method. At low undersaturations, the dissolution reaction appeared to be controlled mainly by surface diffusion with an effective reaction order of 1.9±0.1 with respect to the relative undersaturation. These results together with those obtained by scanning electron microscopy (SEM) suggest a dissolution model. Based on the surface diffusion theory of Burton, Cabrera and Frank (BCF). The interfacial tension between CAP and the aqueous phase calculated from this dissolution model, 9.0 m J m -2, was consistent with its relatively low solubility. An abnormal but interesting dissolution behavior is that the CAP dissolution rate was relatively insensitive to changes in calcium and phosphate concentrations at higher undersaturations, suggesting the importance of the carbonate component under these conditions.

  7. Successful topical dissolution of cholesterol gallbladder stones using ethyl propionate.

    Science.gov (United States)

    Hofmann, A F; Amelsberg, A; Esch, O; Schteingart, C D; Lyche, K; Jinich, H; Vansonnenberg, E; D'Agostino, H B

    1997-06-01

    Topical dissolution of cholesterol gallbladder stones using methyl tert-butyl ether (MTBE) is useful in symptomatic patients judged too ill for surgery. Previous studies showed that ethyl propionate (EP), a C5 ester, dissolves cholesterol gallstones rapidly in vitro, but differs from MTBE in being eliminated so rapidly by the liver that blood levels remain undetectable. Our aim was to test EP as a topical dissolution agent for cholesterol gallbladder stones. Five high-risk patients underwent topical dissolution of gallbladder stones by EP. In three patients, the solvent was instilled via a cholecystostomy tube placed previously to treat acute cholecystitis; in two patients, a percutaneous transhepatic catheter was placed in the gallbladder electively. Gallstone dissolution was assessed by chromatography, by gravimetry, and by catheter cholecystography. Total dissolution of gallstones was obtained in four patients after 6-10 hr of lavage; in the fifth patient, partial gallstone dissolution facilitated basketing of the stones. In two patients, cholesterol dissolution was measured and averaged 30 mg/min. Side effects were limited to one episode of transient hypotension and pain at the infusion site; no patient developed somnolence or nausea. Gallstone elimination was associated with relief of symptoms. EP is an acceptable alternative to MTBE for topical dissolution of cholesterol gallbladder stones in high-risk patients. The lower volatility and rapid hepatic extraction of EP suggest that it may be preferable to MTBE in this investigational procedure.

  8. A better dissolution method for ranitidine tablets USP.

    Science.gov (United States)

    Cappola, M L

    2001-01-01

    Ranitidine tablets USP showed variable intra- and inter-lab dissolution results. In order to ascertain the reason for this behavior, ranitidine tablets USP produced by (BIPI) Boehringer Ingelheim Pharmaceuticals Inc., Ridgefield, CT, and Zantac Tablets (brand of ranitidine USP), Glaxo Inc., Research Triangle, NC, were subjected to the compendia (USP) dissolution testing using paddle and basket apparatus. Two potencies of tablets 150 mg and 300 mg were tested. Comparison of BIPI tablets and matching Zantac tablets indicated that both brands of ranitidine tablets USP had similar dissolution behavior. When the basket apparatus was substituted for the paddle apparatus the overall rate and extent of tablet dissolution increased, while the individual tablet variability decreased. BIPI 150 mg tablets using the basket apparatus, but at reduced rotational speed of 30 rpm, showed increase in rate and extent of drug dissolved, with less individual tablet variability compared to the paddle apparatus at 50 rpm. The 300 mg tablet (30 rpm/basket apparatus) had an initial slower rate, but then rapidly equaled the paddle apparatus dissolution results, and had less individual tablet variability. Paddle apparatus tablet sinkers were used to prevent tablets from sticking to the bottom of the dissolution vessel. Overall dissolution for all tablets with sinkers showed a trend which was more rapid and complete than tablets without sinkers. Results showed that dissolution artifacts for ranitidine tablets could be reduced by the use of baskets or tablet sinkers.

  9. Rate equations for sodium catalyzed amorphous silica dissolution

    Science.gov (United States)

    Rimstidt, J. Donald; Zhang, Yilun; Zhu, Chen

    2016-12-01

    Newly measured amorphous silica dissolution rate data were combined with data from the literature to produce an equation that predicts the dissolution flux (J, mol/m2 s) of amorphous silica as a function of temperature (T, K), sodium concentration (mNa+, molal), and hydrogen ion activity (aH+).

  10. Thermal dissolution of maize starches in aqueous medium

    Science.gov (United States)

    Starches are not soluble in neutral water at room temperature. However, if they are heated in a closed container beyond the boiling point of water, they eventually dissolve. The dissolution temperature depends on the type of starch. The dissolution process was monitored in real time by measuring ...

  11. The effect of fuel chemistry on UO2 dissolution

    Energy Technology Data Exchange (ETDEWEB)

    Casella, Amanda; Hanson, Brady; Miller, William

    2016-08-01

    The dissolution rate of both unirradiated UO2 and used nuclear fuel has been studied by numerous countries as part of the performance assessment of proposed geologic repositories. In the scenario of waste package failure and groundwater infiltration into the fuel, the effects of variables such as temperature, dissolved oxygen, and water and fuel chemistry on the dissolution rates of the fuel are necessary to provide a quantitative estimate of the potential release over geologic time frames. The primary objective of this research was to determine the influence these parameters have on the dissolution rate of unirradiated UO2 under repository conditions and compare them to the rates predicted by current dissolution models. Both unirradiated UO2 and UO2 doped with varying concentrations of Gd2O3, to simulate used fuel composition after long time periods where radiolysis has minor contributions to dissolution, were examined. In general, a rise in temperature increased the dissolution rate of UO2 and had a larger effect on pure UO2 than on those doped with Gd2O3. Oxygen dependence was observed in the UO2 samples with no dopant and increased as the temperature rose; in the doped fuels less dependence was observed. The addition of gadolinia into the UO2 matrix showed a significant decrease in the dissolution rate. The matrix stabilization effect resulting from the dopant proved even more beneficial in lowering the dissolution rate at higher temperatures and dissolved O2 concentrations in the leachate where the rates would typically be elevated.

  12. Overview of chemical modeling of nuclear waste glass dissolution

    Energy Technology Data Exchange (ETDEWEB)

    Bourcier, W.L.

    1991-02-01

    Glass dissolution takes place through metal leaching and hydration of the glass surface accompanied by development of alternation layers of varying crystallinity. The reaction which controls the long-term glass dissolution rate appears to be surface layer dissolution. This reaction is reversible because the buildup of dissolved species in solution slows the dissolution rate due to a decreased dissolution affinity. Glass dissolution rates are therefore highly dependent on silica concentrations in solution because silica is the major component of the alteration layer. Chemical modeling of glass dissolution using reaction path computer codes has successfully been applied to short term experimental tests and used to predict long-term repository performance. Current problems and limitations of the models include a poorly defined long-term glass dissolution mechanism, the use of model parameters determined from the same experiments that the model is used to predict, and the lack of sufficient validation of key assumptions in the modeling approach. Work is in progress that addresses these issues. 41 refs., 7 figs., 2 tabs.

  13. Hydro-chemo-mechanical coupling in sediments: Localized mineral dissolution

    KAUST Repository

    Cha, Minsu

    2016-06-11

    Mineral dissolution is inherently a chemo-hydro-mechanical coupled process. Field evidence and laboratory results show that dissolution may localize and form open conduits in cohesive media such as carbonate rocks. This study focuses on the evolution of localized dissolution in soils (i.e., frictional and non-cohesive granular materials) under effective confining stresses. Experimental results show the development of localized dissolution (“pipe”) when a carbonate-quartz sand is subjected to reactive fluid flow: only loosely packed quartz grains remain within pipes, and the number of pipes decreases away from the inlet port. Concurrent shear wave velocity measurements show a decrease in stiffness during dissolution due to stress and fabric changes, and more complex signal codas anticipate the development of internal heterogeneity. The discrete element method is used to simulate localized vertical dissolution features in granular materials, under constant vertical stress and zero lateral strain far-field boundaries. As porosity increases along dissolution pipes, vertical load is transferred to the surrounding soils and marked force chains develop. In terms of equivalent stress, principal stress rotation takes place within pipes and the sediment reaches the Coulomb failure condition inside pipes and in the surrounding medium. Dissolution pipes alter the geo-plumbing of the subsurface, enhance fluid transport but limit the long term performance of storage systems, alter the fluid pressure and effective stress fields, soften the sediment and may trigger shear failures.

  14. 50 CFR 270.23 - Dissolution of Councils.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 7 2010-10-01 2010-10-01 false Dissolution of Councils. 270.23 Section 270.23 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC... § 270.23 Dissolution of Councils. (a) Petition for termination. (1) A petition to terminate a Council...

  15. 29 CFR 511.5 - Vacancies and dissolution of committees.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Vacancies and dissolution of committees. 511.5 Section 511.5 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS WAGE ORDER PROCEDURE FOR AMERICAN SAMOA § 511.5 Vacancies and dissolution of committees. The...

  16. Frogging It: A Poetic Analysis of Relationship Dissolution

    Science.gov (United States)

    Faulkner, Sandra L.

    2012-01-01

    Often, themes in work and life intertwine; the author recognized that a cadre of poems she had written during the past several years were about relationship dissolution. The poems concerned romantic and friendship dissolution and the aspects of identity creation and loss this entails. The author presents the poems and makes an explicit connection…

  17. Oracle ADF Faces cookbook

    CERN Document Server

    Gawish, Amr

    2014-01-01

    This is a cookbook that covers more than 80 different recipes to teach you about different aspects of Oracle ADF Faces. It follows a practical approach and covers how to build your components for reuse in different applications. This book will also help you in tuning the performance of your ADF Faces application. If you are an ADF developer who wants to harness the power of Oracle ADF Faces to create exceptional user interfaces and reactive applications, this book will provide you with the recipes needed to do just that. You will not need to be familiar with Oracle ADF Faces, but you should be

  18. NONMETALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>20102406 Chen Gang(China University of Geosciences,Beijing 100083,China);Li Fengming Discussion on Geological Characteristics and Genesis of Yuquanshan Graphite Deposit of Xinjiang(Xinjiang Geology,ISSN1000-8845,CN65-1092/P,27(4),2009,p.325-329,4 illus.,4 tables,5 refs.)Key words:graphite deposit,XinjiangYuquanshan graphite deposit of Xinjiang occurs in mica-quartz schist of Xingeer Information which belongs to Xinditate Group of Lower Pt in Kuluketage Block of Tarim paleo-continent,and experiences two mineralizing periods of

  19. Effect of solvent on in vitro dissolution: Summary of results for uranium, americium, and cobalt aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Guilmette, R.A.; Hoover, M.D.

    1995-12-01

    The revised 10 CFR Part 20 has adopted the ICRP Publication 30 method for calculating the committed effective dose equivalent from intakes of radionuclides. This dosimetry scheme requires knowledge or assumptions about the chemical form of the radionuclide, its particle size, and its known or assumed solubility. The solubility is classified as being either D (relatively soluble), W, or Y (relatively insoluble), depending on whether the material dissolves over periods of days, weeks, or years. Although Nuclear Regulatory Commission licensees may wish to take advantage of material-specific knowledge in order to adjust annual limits on intake and derived air concentrations, relatively few radioactive materials to which workers and the general population may be exposed have been adequately characterized either in terms of physicochemical form or solubility. Experimental measurement of solubility using some type of in vitro dissolution measurement system is therefore needed. However, there is currently no clear consensus regarding the appropriate design of in vitro dissolution systems, particularly when considering the range of different radionuclides to be studied, and the complexity of the biological mechanisms involved in the retention and clearance of inhaled deposited radioactive particles. The purpose of this study was to evaluate the effect of the several solvents on the dissolution of four test aerosols ({sup 57}Co{sub 3}O{sub 4}, {sup 241}AmO{sub 2}, ammonium diuranate [ADU], and U{sub 3}O{sub 8}) selected to encompass a variety of chemical and biochemical properties in vivo. The results of this study provide some guidance on the usefulness of in vitro dissolution tests for estimating the solubility of unknown radionuclide particles within the context of a simple model such as the class D, W, and Y formulation of ICRP 30.

  20. Aluminum Target Dissolution in Support of the Pu-238 Program

    Energy Technology Data Exchange (ETDEWEB)

    McFarlane, Joanna [ORNL; Benker, Dennis [ORNL; DePaoli, David W [ORNL; Felker, Leslie Kevin [ORNL; Mattus, Catherine H [ORNL

    2014-09-01

    Selection of an aluminum alloy for target cladding affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the caustic dissolution step, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. We present a study to maximize dissolution of aluminum metal alloy, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as a function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. These data have been compared with published calculations of aluminum phase diagrams. Temperature logging during the transients has been investigated as a means to generate kinetic and mass transport data on the dissolution process. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.

  1. Dissolution kinetics of ulexite prepared under different calcination temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Demirkiran, N.; Kuenkuel, A. [Inonu University, Malatya (Turkey). Faculty of Engineering. Dept. of Chemical Engineering]. E-mail: ndemirkiran@inonu.edu.tr

    2008-10-15

    Ulexite is one of the boron minerals used as a raw material in the production of boron compounds. It contains a substantial amount of hydration water. Using calcination methods, the B{sub 2}O{sub 3} grade of ulexite can be increased. In this study, the effect of calcination temperature on dissolution kinetics of ulexite in ammonium chloride solutions was investigated in a batch reactor employing the parameters of concentration, solid-to-liquid ratio and reaction temperature. It was found that the dissolution rate increased with increasing concentration and reaction temperature and with decreasing solid-to-liquid ratio. The highest dissolution rate was obtained with the sample calcined at 413 K. It was determined that the dissolution rate fit to the second order pseudo-homogeneous model. The activation energy of this dissolution process was found to be 64.3 kJ/mo L. (author)

  2. Apparent Dissolution Kinetics of Diatomite in Alkaline Solution

    Institute of Scientific and Technical Information of China (English)

    DU Gaoxiang; L(U) Guocheng; HE Xuwen

    2013-01-01

    The dissolution kinetics of diatomite in alkaline solution is the theoretical basis for the process optimization of alkali-diatomite reaction and its applications.In this study,the dissolution kinetics of diatomite in NaOH solution is investigated.The results indicate that the dissolution reaction fits well the unreacted shrinking core model for solid-liquid heterogeneous reactions.The apparent reaction order for NaOH is 2 and the apparent activation energy for the reaction (Ea) is 28.06 kJ.mol-1.The intra-particle diffusion through the sodium silicate layer is the rate-controlling step.When the dissolution reaction occurs at the interface of unreacted diatomite solid core,the diffusion in the trans-layer (the liquid film around the wetted particle) reduces the rate of whole dissolution process.

  3. Evaluation of dissolution rate on high plutonium content MOX fuel

    Energy Technology Data Exchange (ETDEWEB)

    Sugaya, Shinichi; Kurita, Ichiro; Endo, Hideo; Higuchi, Hidetoshi; Kihara, Yoshiyuki [Japan Nuclear Cycle Development Inst., Tokai Works, Tokai, Ibaraki (Japan); Ogasawara, Masahiro; Shinada, Masanori; Kowata, Masato [Inspection Development Company Ltd., Tokai, Ibaraki (Japan)

    2002-06-01

    The dissolution rate of high Pu content MOX fuel into nitric acid was measured as a function of Pu content. MOX fuel samples, pressed and sintered, were dissolved in 7 M of boiling nitric acid, and the dissolution rate was measured by analyzing the Pu and U concentration in the solution. The dissolution rate of MOX fuel tended to decrease with the increase in the Pu content and was reduced after 6 hours of dissolution. These results agreed well with previous ones, but the dissolution rate was 3-6 times faster than those. It is estimated that the cause of this difference was due to underestimation of the surface area of MOX fuel powder and the difference of the MOX O/M ratio. (author)

  4. Factors associated with relationship dissolution and post-dissolution adjustment among lesbian adoptive couples.

    Science.gov (United States)

    Farr, Rachel H

    2017-01-02

    Same-sex adoptive couples are increasingly visible, yet few studies have addressed relationship stability and dissolution among these couples. In this study, using a theoretical framework based on Investment Models and Vulnerability-Stress-Adaptation Theory, factors associated with dissolution and post-dissolution adjustment among 27 lesbian adoptive couples were examined across two points. At Wave 1, all 27 couples were together; children were on average 3 years old. Results revealed that nearly one third broke up over 5 years (between Waves 1 and 2). Factors related to shorter relationship length and undermining coparenting at Wave 1 distinguished women who later broke up versus stayed together. Worse mental health at Wave 2 characterized women in dissolved rather than sustained relationships, even with comparable individual adjustment at Wave 1. Weaker parenting alliance and greater dissatisfaction with childcare divisions were reported by women no longer with their partners at Wave 2 as compared with those in enduring partnerships. This research has implications for understanding lesbian relationship dynamics and associations with individual adjustment.

  5. Generalization of affective learning about faces to perceptually similar faces.

    Science.gov (United States)

    Verosky, Sara C; Todorov, Alexander

    2010-06-01

    Different individuals have different (and different-looking) significant others, friends, and foes. The objective of this study was to investigate whether these social face environments can shape individual face preferences. First, participants learned to associate faces with positive, neutral, or negative behaviors. Then, they evaluated morphs combining novel faces with the learned faces. The morphs (65% and 80% novel faces) were within the categorical boundary of the novel faces: They were perceived as those faces in a preliminary study. Moreover, a second preliminary study showed that following the learning, the morphs' categorization as similar to the learned faces was indistinguishable from the categorization of actual novel faces. Nevertheless, in the main experiment, participants evaluated morphs of "positive" faces more positively than morphs of "negative" faces. This learning generalization effect increased as a function of the similarity of the novel faces to the learned faces. The findings suggest that general learning mechanisms based on similarity can account for idiosyncratic face preferences.

  6. NONMETALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>20140876 Gao Junbo(College of Resources and Environmental Engineering,Guizhou University,Guiyang 550025,China);Yang Ruidong Study on the Strontium Isotopic Composition of Large Devonian Barite Deposits from Zhenning,Guizhou Province(Geochimica,

  7. NONMETALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>20122457 Cai Jianshe ( Fujian Institute of Geological Survey and Drawing,Fuzhou 350011,China ) On the Geologic Characteristics and Genesis of the Longtangsi Fluorite Deposit in Pucheng County,Fujian Province ( Geology of Fujian,ISSN1001-3970,CN35-1080 / P,30 ( 4 ), 2011,p.301-306,3illus.,1table,6 refs.,with English abstract ) Key words:fluorspar deposit,Fujian Province

  8. Recycling of electric arc furnace dust through dissolution in deep eutectic ionic liquids and electrowinning.

    Science.gov (United States)

    Bakkar, Ashraf

    2014-09-15

    The dust waste formed during steelmaking in electric arc furnace (EAF) is rich in ferrous and nonferrous metals. Recycling of this dust as a raw material in iron or steel-making is hazardous and therefore it is mostly dumped. This paper demonstrates recycling of EAF dust through selective dissolution of metal oxides in a deep eutectic ionic liquid. It was found that about 60% of Zn and 39% of Pb could be dissolved from the dust when stirred for 48h in 1 choline chloride:2 urea ionic liquid at 60°C. The resultant electrolyte was subsequently fed to a conventional three-electrode cell where cyclic voltammetry (CV) measurements were conducted to describe its electrochemical behavior. Two deposition peaks were determined and ascribed to deposition of zinc and lead. Static potentials were successively applied to electrowin metallic zinc. SEM/EDX investigations showed that the zinc electrowon contained remarkable contents of lead.

  9. Continuous dissolution of irradiated nuclear fuels; Dissolution continue des combustibles nucleaires irradies

    Energy Technology Data Exchange (ETDEWEB)

    Michel, P.; Talmont, X.; Tarnerq, M. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-07-01

    In the case of the continuous dissolution of nuclear fuels, the equations for the calculation of the fuel concentration of the solution flowing out of a pot dissolver have been written. Nitric acid feed flow rates have been calculated in order to obtain an adjusted solution when starting or stopping a dissolution, or when changing the number of rods introduced per hour. Then some transient states brought on by perturbations, have been studied: a) sudden change in nitric acid flow rate; b) continuous drift of the latter; c) sudden change in nitric acid feed concentration; d) transition from a fuel concentration to another by changing the flow rate of nitric acid feed. It has been shown that some transient states cannot be solved with general equations. Computer calculation programs would be probably more useful. (authors) [French] L'etude se rapporte a la dissolution dans l'acide nitrique des combustibles nucleaires irradies, en vue de la recuperation de la matiere fissile qu'ils contiennent. On a etabli, dans le cas de la dissolution continue, les differentes equations permettant le calcul de la concentration en combustible a la sortie d'un dissolveur du type 'marmite'. On a etudie les regimes du debit d'alimentation en acide nitrique a imposer lors du demarrage, de l'arret d'une dissolution, ou lors d'un changement de cadence d'introduction des barreaux, de facon a obtenir une solution ajustee. On a etudie ensuite differents regimes transitoires consecutifs a des perturbations: changement brusque du debit d'acide d'alimentation, derive continue de ce debit, changement brusque de la concentration de l'acide d'alimentation, passage d'une concentration en combustible a une autre par changement du debit d'acide d'alimentation. On a pu montrer que certains regimes transitoires ne peuvent se traiter par des equations generales, et necessiteraient plustot l'etablissement d

  10. Social judgments from faces.

    Science.gov (United States)

    Todorov, Alexander; Mende-Siedlecki, Peter; Dotsch, Ron

    2013-06-01

    People make rapid and consequential social judgments from minimal (non-emotional) facial cues. There has been rapid progress in identifying the perceptual basis of these judgments using data-driven, computational models. In contrast, our understanding of the neural underpinnings of these judgments is rather limited. Meta-analyses of neuroimaging studies find a wide range of seemingly inconsistent responses in the amygdala that co-vary with social judgments from faces. Guided by computational models of social judgments, these responses can be accounted by positing that the amygdala (and posterior face selective regions) tracks face typicality. Atypical faces, whether positively or negatively evaluated, elicit stronger responses in the amygdala. We conclude with the promise of data-driven methods for modeling neural responses to social judgments from faces.

  11. Instabilities in geomaterials induced by dissolution

    Science.gov (United States)

    Stefanou, I.; Sulem, J.

    2015-12-01

    Deformation bands play an important role in reservoir engineering, geological storage, underwater landslides and slow geological procedures. Various mechanisms can be involved at different scales and may be responsible for deformation bands. Mechanical and chemical degradation of the grain skeleton is a softening factor that can lead to compaction, shear or even dilation band formation [1]-[3]. The present study is twofold. On one hand it focuses on the mathematical modeling of chemically induced strain localization instabilities in porous rocks and on the other hand it explores the conditions for their creation [4], [5]. In a saturated porous rock, the progressive mechanical damage of the solid skeleton during deformation, results in the increase of the interface area of the reactants and consequently in the acceleration of the dissolution rate of the solid phase [6]. Under the presence of dissolving fluids the solid skeleton is degraded more rapidly (mass removal because of dissolution), the overall mechanical properties of the system diminish (contraction of the elastic domain - chemical softening), deformations increase and the solid skeleton is further damaged (intergranular fractures, debonding, breakage of the porous network etc.). Based on a micromechanical model, the conditions for deformation band triggering are investigated analytically. The heterogeneity of the microstructure in terms of chemical reactivity of the constituents of the REV is taken into account resulting in a characteristic internal length of the system. The post bifurcation behavior is finally studied both analytically and numerically revealing the thickness of the localized zone. References[1] I. Stefanou and J. Sulem, DOI: 10.1002/2013JB010342 [2] M. Cha and J. C. Santamarina, DOI: 10.1680/geot.14P.115 [3] M. D. Ingraham, K. A. Issen, and D. J. Holcomb, DOI: 10.1007/s11440-013-0275-y [4] K. A. Issen and J. W. Rudnicki, DOI: 10.1029/2000JB900185 [5] J. W. Rudnicki and J. R. Rice, DOI

  12. Release of potassium accompanying the dissolution of rice straw phytolith.

    Science.gov (United States)

    Nguyen, Minh Ngoc; Dultz, Stefan; Picardal, Flynn; Bui, Anh Thi Kim; Pham, Quang Van; Schieber, Juergen

    2015-01-01

    In rice, Si assimilated from the soil solution is deposited in inter- and intracellular spaces throughout the leaf and stems to form silicified structures (so-called phytoliths). Because K is also present in significant concentrations in rice stems and leaves, the question arises if K is immobilized in the mineralized silica during the precipitation of Si. This work determined whether desilification of the phytolith is a factor regulating K release by implementing batch experiments. Solubility of Si and K of the rice straw heated at different temperatures were examined to identify effect of pretreatment. Analyses of phytoliths using SEM-EDX and X-ray tomographic microscopy in conjunction with the results from batch experiments revealed that K might co-exist with occluded organic matter inside the phytolith structure. In the kinetic experiments, corresponding increases of K and Si concentrations in the supernatants were observed which suggested that desilification of the phytolith is a main factor regulating K release. The extent of heat pretreatment of the rice straw is of significant importance with respect to dissolution of the phytolith by affecting organic removal and surface modification. At temperatures lower than 600 °C, corresponding increases of the soluble Si and K with heating temperature have been obviously observed. In contrast, the solubility of Si and K gradually decreased at temperatures above 600 °C. This work provides insights into factors that control release of K and Si from phytolith and a practical recommendation for practices of burning rice straw that may maximize subsequent release of Si and K for crops. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Dissolution of jarosite [KFe 3(SO 4) 2(OH) 6] at pH 2 and 8: Insights from batch experiments and computational modelling

    Science.gov (United States)

    Smith, Adrian M. L.; Hudson-Edwards, Karen A.; Dubbin, William E.; Wright, Kate

    2006-02-01

    Jarosite [KFe 3(SO 4) 2(OH) 6] is a mineral that is common in acidic, sulphate-rich environments, such as acid sulphate soils derived from pyrite-bearing sediments, weathering zones of sulphide ore deposits and acid mine or acid rock drainage (ARD/AMD) sites. The structure of jarosite is based on linear tetrahedral-octahedral-tetrahedral (T-O-T) sheets, made up from slightly distorted FeO 6 octahedra and SO 4 tetrahedra. Batch dissolution experiments carried out on synthetic jarosite at pH 2, to mimic environments affected by ARD/AMD, and at pH 8, to simulate ARD/AMD environments recently remediated with slaked lime (Ca(OH) 2), suggest first order dissolution kinetics. Both dissolution reactions are incongruent, as revealed by non-ideal dissolution of the parent solids and, in the case of the pH 8 dissolution, because a secondary goethite precipitate forms on the surface of the dissolving jarosite grains. The pH 2 dissolution yields only aqueous K, Fe, and SO 4. Aqueous, residual solid, and computational modelling of the jarosite structure and surfaces using the GULP and MARVIN codes, respectively, show for the first time that there is selective dissolution of the A- and T-sites, which contain K and SO 4, respectively, relative to Fe, which is located deep within the T-O-T jarosite structure. These results have implications for the chemistry of ARD/AMD waters, and for understanding reaction pathways of ARD/AMD mineral dissolution.

  14. CTAB-Influenced Electrochemical Dissolution of Silver Dendrites.

    Science.gov (United States)

    O'Regan, Colm; Zhu, Xi; Zhong, Jun; Anand, Utkarsh; Lu, Jingyu; Su, Haibin; Mirsaidov, Utkur

    2016-04-19

    Dendrite formation on the electrodes of a rechargeable battery during the charge-discharge cycle limits its capacity and application due to short-circuits and potential ignition. However, understanding of the underlying dendrite growth and dissolution mechanisms is limited. Here, the electrochemical growth and dissolution of silver dendrites on platinum electrodes immersed in an aqueous silver nitrate (AgNO3) electrolyte solution was investigated using in situ liquid-cell transmission electron microscopy (TEM). The dissolution of Ag dendrites in an AgNO3 solution with added cetyltrimethylammonium bromide (CTAB) surfactant was compared to the dissolution of Ag dendrites in a pure aqueous AgNO3 solution. Significantly, when CTAB was added, dendrite dissolution proceeded in a step-by-step manner, resulting in nanoparticle formation and transient microgrowth stages due to Ostwald ripening. This resulted in complete dissolution of dendrites and "cleaning" of the cell of any silver metal. This is critical for practical battery applications because "dead" lithium is known to cause short circuits and high-discharge rates. In contrast to this, in a pure aqueous AgNO3 solution, without surfactant, dendrites dissolved incompletely back into solution, leaving behind minute traces of disconnected silver particles. Finally, a mechanism for the CTAB-influenced dissolution of silver dendrites was proposed based on electrical field dependent binding energy of CTA(+) to silver.

  15. Dissolution and precipitation behavior of amorphous solid dispersions.

    Science.gov (United States)

    Alonzo, David E; Gao, Yi; Zhou, Deliang; Mo, Huaping; Zhang, Geoff G Z; Taylor, Lynne S

    2011-08-01

    Amorphous solid dispersions (ASDs) are widely utilized in the pharmaceutical industry for bioavailability enhancement of low solubility drugs. The important factors governing the dissolution behavior of these systems are still far from adequately understood. As a consequence, it is of interest to investigate the behavior of these systems during the dissolution process. The purpose of this research was twofold. First, the degree of supersaturation generated upon dissolution as a function of drug-polymer composition was investigated. Second, an investigation was conducted to correlate physical behavior upon dissolution with polymer loading. Felodipine and indomethacin were selected as model drugs and hydroxypropylmethylcellulose (HPMC) and polyvinylpyrrolidone (PVP) were used to form the dispersions. Diffusion and nuclear magnetic resonance spectroscopy experiments revealed that the extent of bulk supersaturation generated on dissolution of the ASD did not depend on the drug-polymer ratio. Interestingly, the maximum supersaturation generated was similar to the predicted amorphous solubility advantage. However, dynamic light scattering measurements revealed that particles on the submicron scale were generated during dissolution of the solid dispersions containing 90% polymer, whereas solid dispersions at a 50% polymer loading did not yield these nanoparticles. The nanoparticles were found to result in anomalous concentration measurements when using in situ ultraviolet spectroscopy. The supersaturation generated upon dissolution of the solid dispersions was maintained for biologically relevant timeframes for the HPMC dispersions, whereas PVP appeared to be a less effective crystallization inhibitor.

  16. Dissolution properties of cerium dibutylphosphate corrosion inhibitors

    NARCIS (Netherlands)

    Soestbergen, M. van; Erich, S.J.F.; Huinink, H.P.; Adan, O.C.G.

    2013-01-01

    The corrosion inhibitor cerium dibutylphosphate, Ce(dbp)3, prevents corrosion by cerium and dbp deposition at the alkaline cathode and acidic anode respectively. The pH dependent Ce(dbp)3 solubility seems to play an essential role in the inhibition degree. We found that Ce(dbp) 3 scarcely dissolves

  17. [Preparation of two poor water soluble drugs - nanoporous ZnO solid dispersions and the mechanism of drug dissolution improvement].

    Science.gov (United States)

    Gao, Bei; Sun, Chang-shan; Zhi, Zhuang-zhi; Wang, Yan; Chang, Di; Wang, Si-ling; Jiang, Tong-ying

    2011-11-01

    Nanoporous ZnO was used as a carrier to prepare drug solid dispersion, the mechanism of which to improve the drug dissolution was also studied. Nanoporous ZnO, obtained through chemical deposition method, was used as a carrier to prepare indomethacin and cilostazol solid dispersions by melt-quenching method, separately. The results of scanning electron microscope, surface area analyzer, fourier transform infra-red spectroscopy, differential scanning calorimeter and X-ray diffraction showed that drugs were implanted into nanopores of ZnO by physical adsorption effect and highly dispersed into nanopores of ZnO in amorphous form, moreover, these nanopores strongly inhibited amorphous recrystallization in the condition of 45 degrees C and 75% RH. In addition, the results of the dissolution tested in vitro exhibited that the accumulated dissolutions of indomethacin and cilostazol solid dispersions achieved about 90% within 5 min and approximately 80% within 30 min. It was indicated in this study that the mechanism of drug dissolution improvement was associated with the effects of nanoporous ZnO carrier on increasing drug dispersion, controlling drug in nanopores as amorphous form and inhibiting amorphous recrystallization.

  18. NONMETALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>20110947 Chen Xinglong(Guizhou Bureau of Nonferrous Metal and Nuclear Geology,Guiyang 550005,China);Gong Heqiang Endowment Factors and Development & Utilization Strategy of Bauxite Resource in North Guizhou Province(Guizhou Geology,ISSN1000-5943,CN52-1059/P,27(2),2010,p.106-110,6 refs.,with English abstract)Key words:bauxite deposit,Guizhou Province20110948 Dang Yanxia(Mineral Resource & Reservoir Evaluation Center,Urumiq 830000,China);Fan Wenjun Geological Features and a Primary Study of Metallogenesis of the Wucaiwang Zeolite Deposit,Fuyun County(Xinjiang Geology,ISSN1000-8845,CN65-1092/P,28(2),2010,p.167-170,2 illus.,1 table,5 refs.)Key words:zeolite deposit,Xinjiang Nearly all zeolite deposits in the world result from low-temperature-alteration of glass-bearing volcanic rocks.The southern slope of the Kalamali Mountain is one of the regions where medium to acid volcanics are major lithological type,thus it is a preferred area to look for zeolite deposit.The Wucaiwang zeolite ore district consists of mainly acid volcanic-clastic rocks.

  19. Dissolution of materials in artificial skin surface film liquids.

    Science.gov (United States)

    Stefaniak, Aleksandr B; Harvey, Christopher J

    2006-12-01

    The dissolution of chemical constituents from jewelry, textiles, cosmetics, drugs, industrial chemicals, and particles in direct and prolonged contact with human skin is often assessed in vitro using artificial skin surface film liquids (SSFL). To provide meaningful results, the composition of artificial SSFL should accurately mimic human sweat and sebum, and the conditions of the in vitro test system should accurately reflect in vivo skin conditions. We summarized the reported composition of human SSFL and compared it to 45 different formulations of artificial sweat and 18 formulations of artificial sebum (studies published from 1940 to 2005). Conditions of in vitro dissolution test systems were reviewed and compared to in vivo skin conditions. The concentrations of individual constituents and pH of artificial sweat and concentrations of artificial sebum constituents are not always within ranges reported for human SSFL. Nearly all artificial SSFL lack many of the constituents in human SSFL. To develop a comprehensive model SSFL, we propose a standard SSFL, modified from the two best published sweat and sebum formulations. Little is known concerning the influence of test system conditions on dissolution, including SSFL temperature, container material composition, agitation, and physicochemical properties of the test article on dissolution. Thus, both a need and an opportunity exist for standardizing the composition of artificial SSFL and in vitro dissolution test methodologies. To standardize in vitro dissolution test systems, we recommend: maintaining artificial SSFL at a biologically relevant temperature appropriate to the human activity being modeled, carefully selecting test and sample storage containers to avoid bias in dissolution measurements, accounting for friction between a test article and skin in a biologically plausible manner, and physicochemical characterization of the test article or material to better understand mechanisms of dissolution and

  20. Enhanced nitrogen deposition over China

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xuejun; Zhang, Ying; Han, Wenxuan; Tang, Aohan; Shen, Jianlin; Cui, Zhenling; Christie, Peter; Zhang, Fusuo [College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193 (China); Vitousek, Peter [Department of Biology, Stanford University, Stanford, California 94305 (United States); Erisman, Jan Willem [VU University Amsterdam, 1081 HV Amsterdam (Netherlands); Goulding, Keith [The Sustainable Soils and Grassland Systems Department, Rothamsted Research, Harpenden AL5 2JQ (United Kingdom); Fangmeier, Andreas [Institute of Landscape and Plant Ecology, University of Hohenheim, 70593 Stuttgart (Germany)

    2013-02-28

    China is experiencing intense air pollution caused in large part by anthropogenic emissions of reactive nitrogen. These emissions result in the deposition of atmospheric nitrogen (N) in terrestrial and aquatic ecosystems, with implications for human and ecosystem health, greenhouse gas balances and biological diversity. However, information on the magnitude and environmental impact of N deposition in China is limited. Here we use nationwide data sets on bulk N deposition, plant foliar N and crop N uptake (from long-term unfertilized soils) to evaluate N deposition dynamics and their effect on ecosystems across China between 1980 and 2010. We find that the average annual bulk deposition of N increased by approximately 8 kilograms of nitrogen per hectare (P < 0.001) between the 1980s (13.2 kilograms of nitrogen per hectare) and the 2000s (21.1 kilograms of nitrogen per hectare). Nitrogen deposition rates in the industrialized and agriculturally intensified regions of China are as high as the peak levels of deposition in northwestern Europe in the 1980s, before the introduction of mitigation measures. Nitrogen from ammonium (NH4+) is the dominant form of N in bulk deposition, but the rate of increase is largest for deposition of N from nitrate (NO3-), in agreement with decreased ratios of NH3 to NOx emissions since 1980. We also find that the impact of N deposition on Chinese ecosystems includes significantly increased plant foliar N concentrations in natural and semi-natural (that is, non-agricultural) ecosystems and increased crop N uptake from long-term-unfertilized croplands. China and other economies are facing a continuing challenge to reduce emissions of reactive nitrogen, N deposition and their negative effects on human health and the environment.

  1. Cytotoxicity and intracellular dissolution of nickel nanowires

    KAUST Repository

    Perez, Jose E.

    2015-12-22

    The assessment of cytotoxicity of nanostructures is a fundamental step for their development as biomedical tools. As widely used nanostructures, nickel nanowires (Ni NWs) seem promising candidates for such applications. In this work, Ni NWs were synthesized and then characterized using vibrating sample magnetometry, energy dispersive X-Ray analysis and electron microscopy. After exposure to the NWs, cytotoxicity was evaluated in terms of cell viability, cell membrane damage and induced apoptosis/necrosis on the model human cell line HCT 116. The influence of NW to cell ratio (10:1 to 1000:1) and exposure times up to 72 hours was analyzed for Ni NWs of 5.4 µm in length, as well as for Ni ions. The results show that cytotoxicity markedly increases past 24 hours of incubation. Cellular uptake of NWs takes place through the phagocytosis pathway, with a fraction of the dose of NWs dissolved inside the cells. Cell death results from a combination of apoptosis and necrosis, where the latter is the outcome of the secondary necrosis pathway. The cytotoxicity of Ni ions and Ni NWs dissolution studies suggest a synergistic toxicity between NW aspect ratio and dissolved Ni, with the cytotoxic effects markedly increasing after 24 hours of incubation.

  2. Dissolution of chromium in sulfuric acid

    Directory of Open Access Journals (Sweden)

    J. P. POPIC

    2002-11-01

    Full Text Available By combining electrochemical corrosion rate measurements and spectrophotometric analysis of the electrolyte it was shown that at room temperature chromium dissolves in deaerated 0.1 M Na2SO4 + H2SO4 (pH 1 solution as Cr(II and Cr(III ions in he ratio Cr(II : Cr(III @ 7 : 1. This process was stable over 4 h without any detectable change. The total corrosion rate of chromium calculated from the analytical data is about 12 times higher, than that determined electrochemically by cathodic Tafel line extrapolation to the corrosion potential. This finding was confirmed by applying the weight-loss method for the determination of the corrosion rate. This enormous difference between these experimentally determined corrosion rates can be explained by the rather fast, “anomalous” dissolution process proposed by Kolotyrkin and coworkers (chemical reaction of Cr with H2O molecules occurring simultaneously with the electrochemical corrosion process.

  3. Canine struvite urolithiasis: problems and their dissolution.

    Science.gov (United States)

    Osborne, C A; Klausner, J S; Krawiec, D R; Griffith, D P

    1981-08-01

    Struvite (magnesium ammonium phosphate) uroliths are found more frequently in the urinary tracts, of dogs than are other types of uroliths. Infection of the urinary tract with urease-producing bacteria, especially staphylococci, plays an important role in urolith formation. An inherited predisposition to urinary tract infection may be associated with the high rat of occurrence of struvite uroliths in some dogs. Diagnosis of struvite urolithiasis should encompass analysis of the mineral composition of calculi and identification of concomitant urinary tract infection. Since urinary tract infections occur as sequelae to abnormalities in local or systemic host-defense mechanisms, appropriate effort should be directed toward detection of these abnormalities. Therapy of struvite urolithiasis should encompass relief of obstruction to outflow when necessary, elimination of existing calculi, eradication or control of urinary tract infection, and prevention of recurrence. Although surgical removal remains as the preferred method to eliminate struvite uroliths from dogs, nonsurgical methods of urolith dissolution should be considered. Recurrence of struvite uroliths may be prevented by various combinations of antimicrobial therapy, administration of urease inhibitors, acidification of urine, and induction of diuresis.

  4. FORMULATION STRATEGY FOR DISSOLUTION ENHANCEMENT OF SIMVASTATIN

    Directory of Open Access Journals (Sweden)

    Neha Parmar et al

    2012-10-01

    Full Text Available The present work aim was “Formulation Strategy for Dissolution Enhancement of Simvastatin”. Simvastatin is lipid lowering drug which is known as HMG CoA reductase. The objective of this study was to increase the solubility of poorly water soluble drug, namely simvastatin, by the formation of solid dispersion and complex and also using the microwave induction technique on these formations. For solid dispersion method dispersion carrier used were poloxamer 407 and gelucire 44/14. The fusion method was used to prepare the dispersions. For inclusion complexation method β-cyclodextrin derivative of cyclodextrin was used to prepare complex with drug. Kneading method was used for formulation. After completion of these two techniques these polymers were used for the microwave induced fusion method. All the ratio of drug and polymer were used to heat for different time interval. These samples were used for solubility measurement. In the solid dispersion technique, simvastatin show higher increase in solubility with gelucire 44/14 in the ratio of 1:5 as compare to poloxamer 407. In the microwave induced fusion method simvastatin show higher solubility with simvastatin with gelucire 44/14 after 10 mins time interval as compare to poloxamer 407 and β-cyclodextrin. Solubility of simvastatin increased higher with gelucire 44/14 by using microwave induced fusion method as compare to other technique. By using gelucire 44/14 with simvastatin it show 94% increase in solubility of simvastatin as compare to pure drug in water.

  5. Dissolution and reduction of magnetite by bacteria

    Science.gov (United States)

    Kostka, J. E.; Nealson, K. H.

    1995-01-01

    Magnetite (Fe3O4) is an iron oxide of mixed oxidation state [Fe(II), Fe(III)] that contributes largely to geomagnetism and plays a significant role in diagenesis in marine and freshwater sediments. Magnetic data are the primary evidence for ocean floor spreading and accurate interpretation of the sedimentary magnetic record depends on an understanding of the conditions under which magnetite is stable. Though chemical reduction of magnetite by dissolved sulfide is well known, biological reduction has not been considered likely based upon thermodynamic considerations. This study shows that marine and freshwater strains of the bacterium Shewanella putrefaciens are capable of the rapid dissolution and reduction of magnetite, converting millimolar amounts to soluble Fe(II)in a few days at room temperature. Conditions under which magnetite reduction is optimal (pH 5-6, 22-37 degrees C) are consistent with an enzymatic process and not with simple chemical reduction. Magnetite reduction requires viable cells and cell contact, and it appears to be coupled to electron transport and growth. In a minimal medium with formate or lactate as the electron donor, more than 10 times the amount of magnetite was reduced over no carbon controls. These data suggest that magnetite reduction is coupled to carbon metabolism in S. putrefaciens. Bacterial reduction rates of magnetite are of the same order of magnitude as those estimated for reduction by sulfide. If such remobilization of magnetite occurs in nature, it could have a major impact on sediment magnetism and diagenesis.

  6. Handbook of Face Recognition

    CERN Document Server

    Li, Stan Z

    2011-01-01

    This highly anticipated new edition provides a comprehensive account of face recognition research and technology, spanning the full range of topics needed for designing operational face recognition systems. After a thorough introductory chapter, each of the following chapters focus on a specific topic, reviewing background information, up-to-date techniques, and recent results, as well as offering challenges and future directions. Features: fully updated, revised and expanded, covering the entire spectrum of concepts, methods, and algorithms for automated face detection and recognition systems

  7. Face Search at Scale.

    Science.gov (United States)

    Wang, Dayong; Otto, Charles; Jain, Anil K

    2016-06-20

    rsons of interest among the billions of shared photos on these websites. Despite significant progress in face recognition, searching a large collection of unconstrained face images remains a difficult problem. To address this challenge, we propose a face search system which combines a fast search procedure, coupled with a state-of-the-art commercial off the shelf (COTS) matcher, in a cascaded framework. Given a probe face, we first filter the large gallery of photos to find the top-k most similar faces using features learned by a convolutional neural network. The k retrieved candidates are re-ranked by combining similarities based on deep features and those output by the COTS matcher. We evaluate the proposed face search system on a gallery containing 80 million web-downloaded face images. Experimental results demonstrate that while the deep features perform worse than the COTS matcher on a mugshot dataset (93.7% vs. 98.6% TAR@FAR of 0.01%), fusing the deep features with the COTS matcher improves the overall performance (99.5% TAR@FAR of 0.01%). This shows that the learned deep features provide complementary information over representations used in state-of-the-art face matchers. On the unconstrained face image benchmarks, the performance of the learned deep features is competitive with reported accuracies. LFW database: 98.20% accuracy under the standard protocol and 88.03% TAR@FAR of 0.1% under the BLUFR protocol; IJB-A benchmark: 51.0% TAR@FAR of 0.1% (verification), rank 1 retrieval of 82.2% (closed-set search), 61.5% FNIR@FAR of 1% (open-set search). The proposed face search system offers an excellent trade-off between accuracy and scalability on galleries with millions of images. Additionally, in a face search experiment involving photos of the Tsarnaev brothers, convicted of the Boston Marathon bombing, the proposed cascade face search system could find the younger brother's (Dzhokhar Tsarnaev) photo at rank 1 in 1 second on a 5M gallery and at rank 8 in 7

  8. A review of non-oxidative dissolution of iron sulphides

    Energy Technology Data Exchange (ETDEWEB)

    Marsland, S.D.; Dawe, R.A.; Kelsall, G.H.

    1988-01-01

    This paper reviews the non-oxidative dissolution of mineral sulphides as a possible source of reservoir souring. It investigates the factors affecting the rate of dissolution/H/sub 2/S evolution and the mechanisms by which the process takes to place. From the information presented it is apparent that no exhaustive kinetic or thermodynamic studies have been carried out in this area. The paper indicates that the non-oxidative dissolution of mineral sulphides, and in particular iron sulphides, is a probable source of hydrogen sulphide generation under reservoir conditions.

  9. On the present and future of dissolution-DNP

    DEFF Research Database (Denmark)

    Ardenkjær-Larsen, Jan Henrik

    2016-01-01

    Dissolution-DNP is a method to create solutions of molecules with nuclear spin polarization close to unity. The many orders of magnitude signal enhancement have enabled many new applications, in particular in vivo MR metabolic imaging. The method relies on solid state dynamic nuclear polarization...... at low temperature followed by a dissolution to produce the room temperature solution of highly polarized spins. This work describes the present and future of dissolution-DNP in the mind of the author. The article describes some of the current trends in the field as well as outlines some of the areas...

  10. METALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>20091594 Bao Yafan(The Third Geologic Survey of Jilin Province,Siping 136000,China);Liu Yanjun Relations between Bashenerxi Granite,West Dongkunlun and Baiganhu Tungsten-Tin Deposit(Jilin Geology,ISSN1001-2427,CN22-1099/P,27(3),2008,p.56-59,67,5 illus.,2 tables,7 refs.,with English abstract)Key words:tungsten ores,tin ores,monzogranite,Kunlun Mountains20091595 Chen Fuwen(Yichang Institute of Geology and Mineral Resources,China Geological Survey,Yichang 443003,China);Dai Pingyun Metallogenetic and Isotopic Chronological Study on the Shenjiaya Gold Deposit in Xuefeng Mountains,Hunan Province(Acta Geologica Sinica,ISSN0001-5717,CN11-1951/P,82(7),2008,p.906-911,3 illus.,2 tables,30 refs.)Key words:gold ores,HunanThe Shenjiaya gold deposit is a representative one

  11. Dissolution Enhancement of Poorly Water Soluble Efavirenz by Hot Melt Extrusion Technique

    Directory of Open Access Journals (Sweden)

    Smita Kolhe

    2013-06-01

    Full Text Available Large number of drugs; including new chemical entity (NCE, are facing the solubility problem [classified as biopharmaceutical classification system (BCS Class II or IV]. Hence extensive development in solubility enhancement is required. Hot melt extrusion (HME is the most widely applied processing techniques useful for preparing granules, pellets, sustained release tablets, implants, transdermal and transmucosal drug delivery systems ,while its major advantages include enhancement of the dissolution rate and bioavailability, controlling or modifying drug release, taste masking, stabilizing the active pharmaceutical ingredient (API. Hot melt extruded dosage forms are generally complex mixtures of API, plastisizers and polymer carriers which are passed through single or twin-screw extruders at high temperature and stress, molten thermoplastic polymers during the extrusion process can function as thermal binders and/or release retardants. Present investigation deals with enhancement of dissolution rate and hence solubility of Efavirenz (Efv, which belongs to BCS class II. Efv is non neucleotide reverse transcriptase inhibitor (NNRTI for first line antiretroviral treatment type 1 with long half life of 52-56 hrs. Solubility enhancement techniques are available in wide range but HME was the preferred technique due to its several advantages. Copovidone (Kollidon VA64 as polymer and polyethylene glycol (PEG 4000, polyoxy 35 castor oil (Cremophor EL and sorbiton monolaurate (Montane 20 PHA as plasticizers were studied and optimized. Evaluation techniques like saturation solubility, effect of temperature on preparation of complexes, differential scanning calorimetry (DSC, x-ray diffraction (XRD, Infra red (IR, dissolution and in vitro permeability studies were carried out. XRD data concluded that HME process demolished the sharp peaks of Efv which indicate the complete conversion of crystal form of Efv to amorphous form. Dissolution and solubility

  12. METALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>20111705 An Junbo(Team 603,Bureau of Nonferrous Metals Geological Exploration of Jilin Province,Hunchun 133300,China);Xu Renjie Geological Features and Ore Genesis of Baishilazi Scheelite Deposit in Yanbian Area(Jilin Geology,ISSN1001-2427,CN22-1099/P,29(3),2010,p.39-43,2 illus.,2 tables,7 refs.)Key words:tungsten ores,Jilin ProvinceThe Baishilazi scheelite deposit is located in contacting zone between the marble of the Late Palaeozoic Qinglongcun Group and the Hercynian biotite granite.The vein and lenticular major ore body is obviously controlled by NE-extending faults and con

  13. Facies, dissolution seams and stable isotope compositions of the Rohtas Limestone (Vindhyan Supergroup) in the Son valley area, central India

    Indian Academy of Sciences (India)

    S Banerjee; S K Bhattacharya; S Sarkar

    2005-02-01

    The early Mesoproterozoic Rohtas Limestone in the Son valley area of central India represents an overall shallowing-upward carbonate succession. Detailed facies analysis of the limestone reveals outer- to inner-shelf deposition in an open marine setting. Wave-ripples, hummocky cross strat- ifications and edgewise conglomerates argue against a deep marine depositional model for the Rohtas Limestone proposed earlier. Stable isotope analysis of the limestone shows that 13C and 18O values are compatible with the early Mesoproterozoic open seawater composition. The ribbon limestone facies in the Rohtas Limestone is characterized by micritic beds, each decoupled in a lower band enriched and an upper band depleted in dissolution seams. Band-wise isotopic analysis reveals systematic short-term variations. Comparative enrichment of the heavier isotopes in the upper bands is attributed to early cementation from sea water and water derived from the lower band undergoing dissolution because of lowering of pH at depth. The short-term positive shifts in isotopic compositions in almost every upward gradational transition from a seamed band to a non-seamed band support the contention that dissolution seams here are of early diagenetic origin, although their formation was accentuated under overburden pressure.

  14. Modeling calcium dissolution from oil shale ash: Part 1. Ca dissolution during ash washing in a batch reactor

    Energy Technology Data Exchange (ETDEWEB)

    Velts, O.; Kallas, J. [Tallinn University of Technology, Laboratory of Inorganic Materials, 5 Ehitajate Str., Tallinn 19086 (Estonia); Lappeenranta University of Technology, Laboratory of Separation Technology, Skinnarilankatu 34, Lappeenranta 53851 (Finland); Hautaniemi, M. [Lappeenranta University of Technology, Laboratory of Separation Technology, Skinnarilankatu 34, Lappeenranta 53851 (Finland); Kuusik, R. [Tallinn University of Technology, Laboratory of Inorganic Materials, 5 Ehitajate Str., Tallinn 19086 (Estonia)

    2010-05-15

    Batch dissolution experiments were carried out to investigate Ca leachability from oil shale ashes formed in boilers operating with different combustion technologies. The main characteristics of Ca dissolution equilibrium and dynamics, including Ca internal mass transfer through effective diffusion coefficients inside the ash particle were evaluated. Based on the collected data, models allowing simulation of the Ca dissolution process from oil shale ashes during ash washing in a batch reactor were developed. The models are a set of differential equations that describe the changes in Ca content in the solid and liquid phase of the ash-water suspension. (author)

  15. METALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>20090243 Chen Zhibin (Hebei Institute of Geological Survey, Shijiazhuang 050081, China) Ore-Controlling Factors of the Beichagoumen Ag-Polymetallic Deposits in Northern Hebei Province (Geological Survey and Research, ISSN1672-4135, CN12-1353/P, 31(1), 2008, p.1-5, 3 illus., 10 refs.)

  16. METALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>20131565 Cai Lianyou(No.332 Geological Team,Bureau of Geology and Mineral Resources Exploration of Anhui Province,Huangshan 245000,China);Weng Wangfei Geological Characteristics and Genesis Analysis of Guocun Navajoite Deposit in South Anhui Province(Mineral Resources and Geology,

  17. METALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>20102341 Bao Peisheng(Institute of Geology,Chinese Academy of Geological Science,Beijing 100037,China)Further Discussion on the Genesis of the Podiform Chromite Deposits in the Ophiolites-Questioning about the Rock:Melt Interaction Metallogeny(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,28(12),2009,p.1741-1761

  18. NONMETALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>20131601 Gao Junbo(College of Resources and Environmental Engineering,Guizhou University,Guiyang 550003,China);Yang Ruidong Hydrothermal Venting-Flowing Sedimentation Characteristics of Devonian Barite Deposits from Leji,Zhenning County,Guizhou Province(Acta Sedimentologica Sinica,ISSN1000-0550,CN62-1038/P,30(3),

  19. Dissolution of cellulose in ionic liquid: A review

    Science.gov (United States)

    Mohd, N.; Draman, S. F. S.; Salleh, M. S. N.; Yusof, N. B.

    2017-02-01

    Dissolution of cellulose with ionic liquids (IL) and deep eutectic solvent (DES) lets the comprehensive dissolution of cellulose. Basically, cellulose can be dissolved, in some hydrophilic ionic liquids, such as 1-butyl-3-methylimidazolium chloride (BMIMCl) and 1-allyl-3-methylimidazolium chloride (AMIMCl). Chloride based ionic liquids are suitable solvents for cellulose dissolution. Although the ILs is very useful in fine chemical industry, its application in the pharmaceutical and food industry have been very limited due to issues with toxicity, purity, and high cost. Seeing to these limitations, new green alternative solvent which is DES was used. This green solvents, may be definitely treated as the next-generation reagents for more sustainable industrial development. Thus, this review aims to discuss the dissolution of cellulose either with ionic liquids or DES and its application.

  20. Dissolution of FB-Line Residues Containing Beryllium Metal

    Energy Technology Data Exchange (ETDEWEB)

    RUDISILL, TRACY S.; CROWDER, MARK L.

    2005-09-06

    Scrap materials containing plutonium (Pu) metal were dissolved at the Savannah River Site (SRS) as part of a program to disposition nuclear materials during the deactivation of the FB-Line facility. Some of these items contained both Pu and beryllium (Be) metal as a composite material. The Pu and Be metals were physically separated to minimize the amount of Be associated with the Pu; however, a dissolution flowsheet was required to dissolve small amounts of Be combined with the Pu metal using a dissolving solution containing nitric acid (HNO{sub 3}) and potassium fluoride (KF). Since the dissolution of Pu metal in HNO{sub 3}/fluoride (F{sup -}) solutions was well understood, the primary focus of the flowsheet development was the dissolution of Be metal. Initially, small-scale experiments were used to measure the dissolution rate of Be metal foils using conditions effective for the dissolution of Pu metal. The experiments demonstrated that the dissolution rate was nearly independent of the HNO{sub 3} concentration over the limited range of investigation and only a moderate to weak function of the F{sup -} concentration. The effect of temperature was more pronounced, significantly increasing the dissolution rate between 40 and 105 C. The offgas analysis from three Be metal foil dissolutions demonstrated that the production of hydrogen (H{sub 2}) was sensitive to the HNO{sub 3} concentration, decreasing by a factor of approximately two when the concentration was increased from 4 to 8 M. In subsequent experiments, complete dissolution of Be samples from a Pu/Be composite material was achieved in a 4 M HNO{sub 3} solution containing 0.1-0.2 M KF. Gas samples collected during each experiment showed that the maximum H{sub 2} generation rate occurred at temperatures below 70-80 C. A Pu metal dissolution experiment was performed using a 4 M HNO{sub 3}/0.1 M KF solution at 80 C to demonstrate flowsheet conditions developed for the dissolution of Be metal. As the reaction

  1. Dissolution kinetics and behavior of δ phase in Inconel 718

    Institute of Scientific and Technical Information of China (English)

    蔡大勇; 张伟红; 聂璞林; 刘文昌; 姚枚

    2003-01-01

    Dissolution kinetics of δ phase in Inconel 718 at 980,1000 and 1020℃ respectively was established using the quantitative X-ray diffraction(XRD)method.Microstructure evolution during dissolution process was analyzed with scanning electron microscopy(SEM).Dissolution rate of δ phase during high temperature heating keeps at a high level at the beginning stage,and then decreases gradually with the increase of heating time.A dynamic equilibrium state approaches after being heated at 980℃ for more than 30 min and at 1000℃ for more than 2 h,and the equilibrium mass fraction are 3% and 0.6% respectively.δ phase fully dissolves into the austenitic matrix after being heated at 1020℃ for more than 2 h.The dissolution and fracture effects cause the morphology evolution of δphase from long needle shape to short bars or particles at high temperature.

  2. On the effects of subsurface parameters on evaporite dissolution (Switzerland)

    Science.gov (United States)

    Zidane, Ali; Zechner, Eric; Huggenberger, Peter; Younes, Anis

    2014-05-01

    Uncontrolled subsurface evaporite dissolution could lead to hazards such as land subsidence. Observed subsidences in a study area of Northwestern Switzerland were mainly due to subsurface dissolution (subrosion) of evaporites such as halite and gypsum. A set of 2D density driven flow simulations were evaluated along 1000 m long and 150 m deep 2D cross sections within the study area that is characterized by tectonic horst and graben structures. The simulations were conducted to study the effect of the different subsurface parameters that could affect the dissolution process. The heterogeneity of normal faults and its impact on the dissolution of evaporites is studied by considering several permeable faults that include non-permeable areas. The mixed finite element method (MFE) is used to solve the flow equation, coupled with the multipoint flux approximation (MPFA) and the discontinuous Galerkin method (DG) to solve the diffusion and the advection parts of the transport equation.

  3. The influence of milling on the dissolution performance of simvastatin

    DEFF Research Database (Denmark)

    Zimper, Ulrike; Aaltonen, Jaakko; Krauel-Goellner, Karen

    2012-01-01

    properties such as solubility and dissolution rate and, therefore, process induced solid state modifications need to be monitored. The aim of this study was two-fold: firstly, to investigate the dissolution rates of milled and unmilled simvastatin; and secondly, to screen for the main milling factors...... milling frequency, milling time and ball quantity at a set drug load, out of which milling frequency was found to be the most important factor for particle size as well as process induced disorder. Milling frequency and milling time exhibited an interaction effect on the responses. The optimum milling...... revealed that the process induced disorder was negligible with regard to the dissolution rate. The predicted primary particle size of 1.4 µm could be confirmed experimentally, but due to agglomeration of the primary particles a dissolution rate advantage was not shown, highlighting the importance...

  4. Formulation and Dissolution Study of Valsartan Immediate Release Tablets

    Directory of Open Access Journals (Sweden)

    B. Brahmaiah*, K. Sasikanth, Sreekanth Nama , P.Suresh, Patan Adam Khan

    2013-06-01

    Full Text Available In the present study, design of oral immediate release tablets of Valsartan by direct compression techniquewas carried out. The main aim and objective of the work is to formulate immediate release tablets usingdifferent direct compression vehicles (DCV’S in different ratios. The main motive is to compare thedissolution profile of these formulations and conclude the best formulation which release drug at a fasterrate. To determine the best fit dissolution profile for the dosage forms. Valsartan tablets were formulated byusing microcrystalline cellulose (diluents, potato starch, acacia (binder and magnesium stearate(lubricant. The granules were compressed into tablets and were subjected to dissolution studies. Thedissolution profile of the formulation F2 was found to have better dissolution rate compared to others. TheIn-vitro dissolution studies of all the formulations were conducted and the results were obtained, it wasconcluded that formulation F2 was the best with fast release of drug compared to others.

  5. Influence of the Efavirenz Micronization on Tableting and Dissolution

    Directory of Open Access Journals (Sweden)

    Lucio Mendes Cabral

    2012-09-01

    Full Text Available The purpose of this study was to propose an analytical procedure that provides the effects of particle size and surface area on dissolution of efavirenz. Five different batches obtained by different micronization processes and with different particle size distribution and surface area were studied. The preformulation studies and dissolution curves were used to confirm the particle size distribution effect on drug solubility. No polymorphic variety or amorphization was observed in the tested batches and the particle size distribution was determined as directly responsible for the improvement of drug dissolution. The influence of the preparation process on the tablets derived from efavirenz was observed in the final dissolution result in which agglomeration, usually seen in non-lipophilic micronized material, was avoided through the use of an appropriate wet granulation method. For these reasons, micronization may represent one viable alternative for the formulation of brick dust drugs.

  6. Sticky physics of joy: On the dissolution of spherical candies

    CERN Document Server

    Windisch, Andreas; Popescu, Anita

    2012-01-01

    Assuming a constant mass-decrease per unit-surface and -time we provide a very simplistic model for the dissolution process of spherical candies. The aim is to investigate the quantitative behavior of the dissolution process throughout the act of eating the candy. In our model we do not take any microscopic mechanism of the dissolution process into account, but rather provide an estimate which is based on easy-to-follow calculations. Having obtained a description based on this calculation, we confirm the assumed behavior by providing experimental data of the dissolution process. Besides a deviation from our prediction caused by the production process of the candies below a diameter of 2 mm, we find good agreement with our model-based expectations. Serious questions on the optimal strategy of enjoying a candy will be addressed, like whether it is wise to split the candy by breaking it with the teeth or not.

  7. Effect of alteration phase formation on the glass dissolution rate

    Energy Technology Data Exchange (ETDEWEB)

    Ebert, W.L.

    1997-10-01

    The dissolution rates of many glasses have been observed to increase upon the formation of certain alteration phases. It is important to understand the mechanism by which alteration phases affect glass corrosion behavior and the glass dissolution rate to reliably predict whether or not similar effects will occur in a disposal environment and the impact of phase formation on the long-term performance of waste glass. While solid state transformation of a glass to thermodynamically more stable phases in kinetically prohibitive, contact by water provides an energetically favorable pathway for this transformation to occur by a dissolution-reprecipitation mechanism. The kinetics of the transformation depends on the dissolution kinetics of the glass and the precipitation kinetics of the alteration phases. The rates of these two processes are linked primarily through the solution activity of orthosilicic acid (and perhaps also that of an aluminum-bearing species).

  8. Controlled dissolution of colossal quantities of nitrogen in stainless steel

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Somers, Marcel A. J.

    2006-01-01

    The solubility of nitrogen in austenitic stainless steel was investigated thermogravimetrically by equilibrating thin foils of AISI 304 and AISI 316 in ammonia/hydrogen gas mixtures. Controlled dissolution of colossal amounts of nitrogen under metastable equilibrium conditions was realized...

  9. investigation of dissolution kinetics of a nigerian columbite in ...

    African Journals Online (AJOL)

    user

    1,2 DEPARTMENT OF CHEMICAL ENGINEERING, OBAFEMI AWOLOWO UNIVERSITY, ILE-IFE, OSUN ... Experimental results indicate that the dissolution rate is chemical reaction ..... [10] Yagi, S. and Kunii, D. “Fluidized-solids reactors with.

  10. wax matrix tablets and its implication on dissolution prof

    African Journals Online (AJOL)

    The release rate increased with increase in concentrations of the non- ionic ... analysed dissolution data revealed that the drug release fit first order flux and Higuchi square root of time model ... etc (Adeyeye and Price, 1991; 1994; Bodmeier et.

  11. Biologically mediated dissolution of volcanic glass in seawater

    NARCIS (Netherlands)

    Staudigel, H; Yayanos, A; Chastain, R; Davies, G.T.; Verdurmen, E.A Th; Schiffmann, P; Bourcier, R; de Baar, H.J.W.

    1998-01-01

    We studied the effects of biological mediation on the dissolution of basaltic glass in seawater. Experiments with typical seawater microbial populations were contrasted with a sterile control, and reactions were monitored chemically and isotopically. Biologically mediated experiments produce twice

  12. Kinetics of reductive bulk dissolution of lepidocrocite, ferrihydrite, and geothite

    DEFF Research Database (Denmark)

    Larsen, O.; Postma, Diederik Jan

    2001-01-01

    The variation in Fe-oxide reactivity was investigated by studying the kinetics of bulk reductive dissolution of a suite of synthetic Fe-oxides in 10 mM ascorbic acid at pH 3. The Fe-oxides comprised three different ferrihydrites, five lepidocrocites, and a poorly crystalline goethite. During one...... of the reduction experiments, lepidocrocite crystals were subsampled and the change in crystal habit and size distribution was studied by transmission electron microscopy. The rate of complete dissolution was described by the function J/m0 5 k9(m/m0)g where J is the overall rate of dissolution (mol/s), m0...... for lepidocrocite showed strong etch-pitting of the crystals parallel to the c-axis resulting ultimately in disintegration of the crystals. For the different iron oxides, the initial rate was independent of the specific surface area, emphasizing the importance of the crystal structure for the dissolution rate...

  13. Studies on PEM fuel cell noble metal catalyst dissolution

    DEFF Research Database (Denmark)

    Andersen, S. M.; Grahl-Madsen, L.; Skou, E. M.

    2011-01-01

    A combination of electrochemical, spectroscopic and gravimetric methods was carried out on Proton Exchange Membrane (PEM) fuel cell electrodes with the focus on platinum and ruthenium catalysts dissolution, and the membrane degradation. In cyclic voltammetry (CV) experiments, the noble metals were...... found to dissolve in 1 M sulfuric acid solution and the dissolution increased exponentially with the upper potential limit (UPL) between 0.6 and 1.6 vs. RHE. 2-20% of the Pt (depending on the catalyst type) was found to be dissolved during the experiments. Under the same conditions, 30-100% of the Ru...... (depending on the catalyst type) was found to be dissolved. The faster dissolution of ruthenium compared to platinum in the alloy type catalysts was also confirmed by X-ray diffraction measurements. The dissolution of the carbon supported catalyst was found one order of magnitude higher than the unsupported...

  14. TANK 12 SLUDGE CHARACTERIZATION AND ALUMINUM DISSOLUTION DEMONSTRATION

    Energy Technology Data Exchange (ETDEWEB)

    Reboul, S; Michael Hay, M; Kristine Zeigler, K; Michael Stone, M

    2009-03-25

    A 3-L sludge slurry sample from Tank 12 was characterized and then processed through an aluminum dissolution demonstration. The dominant constituent of the sludge was found to be aluminum in the form of boehmite. The iron content was minor, about one-tenth that of the aluminum. The salt content of the supernatant was relatively high, with a sodium concentration of {approx}7 M. Due to these characteristics, the yield stress and plastic viscosity of the unprocessed slurry were relatively high (19 Pa and 27 cP), and the settling rate of the sludge was relatively low ({approx}20% settling over a two and a half week period). Prior to performing aluminum dissolution, plutonium and gadolinium were added to the slurry to simulate receipt of plutonium waste from H-Canyon. Aluminum dissolution was performed over a 26 day period at a temperature of 65 C. Approximately 60% of the insoluble aluminum dissolved during the demonstration, with the rate of dissolution slowing significantly by the end of the demonstration period. In contrast, approximately 20% of the plutonium and less than 1% of the gadolinium partitioned to the liquid phase. However, about a third of the liquid phase plutonium became solubilized prior to the dissolution period, when the H-Canyon plutonium/gadolinium simulant was added to the Tank 12 slurry. Quantification of iron dissolution was less clear, but appeared to be on the order of 1% based on the majority of data (a minor portion of the data suggested iron dissolution could be as high as 10%). The yield stress of the post-dissolution slurry (2.5 Pa) was an order of magnitude lower than the initial slurry, due most likely to the reduced insoluble solids content caused by aluminum dissolution. In contrast, the plastic viscosity remained unchanged (27 cP). The settling rate of the post-dissolution slurry was higher than the initial slurry, but still relatively low compared to settling of typical high iron content/low salt content sludges. Approximately 40

  15. Tank 12 Sludge Characterization and Aluminum Dissolution Demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Reboul, S.; Hay, M.; Zeigler, K; Stone, M.

    2010-05-05

    A 3-L sludge slurry sample from Tank 12 was characterized and then processed through an aluminum dissolution demonstration. The dominant constituent of the sludge was found to be aluminum in the form of boehmite. The iron content was minor, about one-tenth that of the aluminum. The salt content of the supernatant was relatively high, with a sodium concentration of {approx}7 M. Due to these characteristics, the yield stress and plastic viscosity of the unprocessed slurry were relatively high (19 Pa and 27 cP), and the settling rate of the sludge was relatively low ({approx}20% settling over a two and a half week period). Prior to performing aluminum dissolution, plutonium and gadolinium were added to the slurry to simulate receipt of plutonium waste from H-Canyon. Aluminum dissolution was performed over a 26 day period at a temperature of 65 C. Approximately 60% of the insoluble aluminum dissolved during the demonstration, with the rate of dissolution slowing significantly by the end of the demonstration period. In contrast, approximately 20% of the plutonium and less than 1% of the gadolinium partitioned to the liquid phase. However, about a third of the liquid phase plutonium became solubilized prior to the dissolution period, when the H-Canyon plutonium/gadolinium simulant was added to the Tank 12 slurry. Quantification of iron dissolution was less clear, but appeared to be on the order of 1% based on the majority of data (a minor portion of the data suggested iron dissolution could be as high as 10%). The yield stress of the post-dissolution slurry (2.5 Pa) was an order of magnitude lower than the initial slurry, due most likely to the reduced insoluble solids content caused by aluminum dissolution. In contrast, the plastic viscosity remained unchanged (27 cP). The settling rate of the post-dissolution slurry was higher than the initial slurry, but still relatively low compared to settling of typical high iron content/low salt content sludges. Approximately 40

  16. Comparison of face Recognition Algorithms on Dummy Faces

    Directory of Open Access Journals (Sweden)

    Aruni Singh

    2012-09-01

    Full Text Available In the age of rising crime face recognition is enormously important in the contexts of computer vision, psychology, surveillance, fraud detection, pattern recognition, neural network, content based video processing, etc. Face is a non intrusive strong biometrics for identification and hence criminals always try to hide their facial organs by different artificial means such as plastic surgery, disguise and dummy. The availability of a comprehensive face database is crucial to test the performance of these face recognition algorithms. However, while existing publicly-available face databases contain face images with a wide variety of poses, illumination, gestures and face occlusions but there is no dummy face database is available in public domain. The contributions of this research paper are: i Preparation of dummy face database of 110 subjects ii Comparison of some texture based, feature based and holistic face recognition algorithms on that dummy face database, iii Critical analysis of these types of algorithms on dummy face database.

  17. Is Face Distinctiveness Gender Based?

    Science.gov (United States)

    Baudouin, Jean-Yves; Gallay, Mathieu

    2006-01-01

    Two experiments were carried out to study the role of gender category in evaluations of face distinctiveness. In Experiment 1, participants had to evaluate the distinctiveness and the femininity-masculinity of real or artificial composite faces. The composite faces were created by blending either faces of the same gender (sexed composite faces,…

  18. A Fundamental Paradigm for Coral Reef Carbonate Sediment Dissolution

    Directory of Open Access Journals (Sweden)

    Andreas J Andersson

    2015-07-01

    Full Text Available The long-term success of coral reefs depends on a positive balance of calcium carbonate production exceeding dissolution, erosion, and material export. As a result of ocean acidification, coral reefs could transition from net accretion to net erosion owing to decreasing rates of calcification and increasing rates of chemical dissolution and bioerosion. Here, I present a fundamental paradigm that aims to explain the main driver of carbonate sediment dissolution on coral reefs based on theory and a new empirical dataset of pore water carbonate chemistry from the Bermuda coral reef platform. The paradigm shows that carbonate sediment dissolution is most strongly controlled by the extent of organic matter decomposition in the sediments, but that the magnitude of dissolution is influenced by how much decomposition is required to reach pore water undersaturation with respect to the most soluble bulk carbonate mineral phase present in the sediments, a condition defined as the Carbonate Critical Threshold (CCT. Decomposition of organic matter beyond the CCT under aerobic conditions results in stoichiometric proportional dissolution of carbonate sediments. As ocean acidification proceeds over the next several decades, the extent of organic matter decomposition required to reach the CCT will decrease, carbonate dissolution will increase, and subsequently the accumulation of carbonate sediments will decrease. Since drastic reductions in anthropogenic CO2 emission are unlikely in the foreseeable future, the paradigm shows that active controls and reduction of organic matter input to coral reefs at the local scale might be an effective mitigation strategy to prevent or delay coral reefs transitioning to a state of net dissolution.

  19. Dissolution-passivation model for zirconium alloys in fluorinated media

    Energy Technology Data Exchange (ETDEWEB)

    Prono, J. [Zircotube, Paimboeuf (France); Caprani, A. [Univ. of Paris VII (France); Jaszay, T.; Frayret, J.P. [Ecole Nat. Sup. de Mecanique, Nantes (France)

    1992-12-31

    Considering the shape of the steady state current-potential curve, we proposed a dissolution-passivation model composed of five determining steps and we calculated the associated elementary rates. Two different compounds of tetravalent zirconium are involved in the formation of the surface film. The influence of temperature on the elementary rates allows us to consider the chemical dissolution as the slowest steps and to involve fluoride in the formation of the film in the vicinity of the corrosion potential.

  20. The effect of fuel chemistry on UO2 dissolution

    Science.gov (United States)

    Casella, Amanda; Hanson, Brady; Miller, William

    2016-08-01

    The dissolution rate of both unirradiated UO2 and used nuclear fuel has been studied by numerous countries as part of the performance assessment of proposed geologic repositories. In the scenario of waste package failure and groundwater contact with the fuel, the effects of variables such as temperature, dissolved oxygen, and water and fuel chemistry on the dissolution rates of the fuel are necessary to provide a quantitative estimate of the potential release over geologic time frames. The primary objective of this research was to determine the influence these parameters, with primary focus on the fuel chemistry, have on the dissolution rate of unirradiated UO2 under oxidizing repository conditions and compare them to the rates predicted by current dissolution models. Both unirradiated UO2 and UO2 doped with varying concentrations of Gd2O3, to simulate used fuel composition after long time periods when radiolysis has minor contributions to dissolution, were examined. In general, a rise in temperature increased the dissolution rate of UO2 and had a larger effect on pure UO2 than on those doped with Gd2O3. Oxygen dependence was observed in the UO2 samples with no dopant and increased as the temperature rose; in the doped fuels less dependence was observed. The addition of gadolinia into the UO2 matrix resulted in a significant decrease in the dissolution rate. The matrix stabilization effect resulting from the dopant proved even more beneficial in lowering the dissolution rate at higher temperatures and dissolved O2 concentrations in the leachate where the rates would typically be elevated.

  1. Investigating Dissolution and Precipitation Phenomena with a Smartphone Microscope

    Energy Technology Data Exchange (ETDEWEB)

    Lumetta, Gregg J.; Arcia, Edgar

    2016-10-11

    A novel smartphone microscope can be used to observe the dissolution and crystallization of sodium chloride at a microscopic level. Observation of these seemingly simple phenomena through the microscope at 100× magnification can actually reveal some surprising behavior. These experiments offer the opportunity to discuss some basic concepts such as how the morphological features of the crystals dictates how the dissolution process proceeds, and how materials can be purified by re-crystallization techniques.

  2. Dissolution of nuclear fuels; Disolucion de combustibles Nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Uriarte Hueda, A.; Berberana Eizmendi, M.; Rainey, R.

    1968-07-01

    A laboratory study was made of the instantaneous dissolution rate (IDR) for unirradiated uranium metal rods and UO{sub 2}, PuO{sub 2} and PuO{sub 2}-UO{sub 2} pellets in boiling nitric acid alone and with additives. The uranium metal and UO{sub 2} dissolved readily in nitric acid alone; PuO{sub 2} dissolved slowly even with the addition of fluoride; PuO{sub 2}-UO{sub 2} pellets containing as much as 35% PuO{sub 2} in UO{sub 2} gave values of the instantaneous dissolution rate to indicate can be dissolved with nitric acid alone. An equation to calculate the time for complete dissolution has been determinate in function of the instantaneous dissolution rates. The calculated values agree with the experimental. Uranium dioxide pellets from various sources but all having a same density varied in instantaneous dissolution rate. All the pellets, however, have dissolved ved in the same time. The time for complete dissolution of PuO{sub 2}-UO{sub 2} pellets, having the same composition, and the concentration of the used reagents are function of the used reagents are function of the fabrication method. (Author) 8 refs.

  3. FORMULATION AND DISSOLUTION STUDY OF DILTIAZEM HYDROCHLORIDE IMMEDIATE RELEASE TABLETS

    Directory of Open Access Journals (Sweden)

    BRAHMAIAH BONTHAGARALA

    2014-08-01

    Full Text Available Objective: The main aim and objective of the work is to formulate immediate release tablets using different direct compression vehicles (DCV’S in different ratios. Methods: In the present study, design of oral immediate release tablets of Diltiazem hydrochloride by direct compression technique was carried out. Results: The main motive is to compare the dissolution profile of these formulations and conclude the best formulation which release drug at a faster rate . To determine the best fit dissolution profile for the dosage forms. Diltiazem hydrochloride tablets were formulated by using microcrystalline cellulose (diluent, potato starch, acacia (binder and magnesium stearate (lubricant. The granules were compressed into tablets and were subjected to dissolution studies. The dissolution profile of the formulation F2 was found to have better dissolution rate compared to others. Conclusion: The Invitro dissolution studies of all the formulations were conducted and the results were obtained, it was concluded that formulation F2 was the best with fast release of drug compared to others.

  4. The Mechanism of Surface Chemical Kinetics of Dissolution of Minerals

    Institute of Scientific and Technical Information of China (English)

    谭凯旋; 张哲儒; 等

    1996-01-01

    This paper deals with the mechanism of dissolution reaction kinetics of minerals in aqueous solution based on the theory of surface chemistry.Surface chemical catalysis would lead to an obvous decrease in active energy of dissolution reaction of minerals.The dissolution rate of minerals is controlled by suface adsorption,surface exchange reaction and desorption,depending on pH of the solution and is directly proportional to δHn0+,When controlled by surface adsorption,i.e.,nθ=1,the dissolution rate will decrease with increasing pH;when controlled by surface exchane reaction,i.e.,nθ=0,the dissolution rate is independent of pH;when controlled by desorption,nθis a positive decimal between 0 and 1 in acidic solution and a negative decimal between-1 and 0 in alkaline solution.Dissolution of many minerals is controlled by surface adsorption and/or surface exchange reactions under acid conditions and by desorption under alkaline conditions.

  5. Dissolution testing for generic drugs: an FDA perspective.

    Science.gov (United States)

    Anand, Om; Yu, Lawrence X; Conner, Dale P; Davit, Barbara M

    2011-09-01

    In vitro dissolution testing is an important tool used for development and approval of generic dosage forms. The objective of this article is to summarize how dissolution testing is used for the approval of safe and effective generic drug products in the United States (US). Dissolution testing is routinely used for stability and quality control purposes for both oral and non-oral dosage forms. The dissolution method should be developed using an appropriate validated method depending on the dosage form. There are several ways in which dissolution testing plays a pivotal role in regulatory decision-making. It may be used to waive in vivo bioequivalence (BE) study requirements, as BE documentation for Scale Up and Post Approval Changes (SUPAC), and to predict the potential for a modified-release (MR) drug product to dose-dump if co-administered with alcoholic beverages. Thus, in vitro dissolution testing plays a major role in FDA's efforts to reduce the regulatory burden and unnecessary human studies in generic drug development without sacrificing the quality of the drug products.

  6. Oxidative dissolution of silver nanoparticles: A new theoretical approach.

    Science.gov (United States)

    Adamczyk, Zbigniew; Oćwieja, Magdalena; Mrowiec, Halina; Walas, Stanisław; Lupa, Dawid

    2016-05-01

    A general model of an oxidative dissolution of silver particle suspensions was developed that rigorously considers the bulk and surface solute transport. A two-step surface reaction scheme was proposed that comprises the formation of the silver oxide phase by direct oxidation and the acidic dissolution of this phase leading to silver ion release. By considering this, a complete set of equations is formulated describing oxygen and silver ion transport to and from particles' surfaces. These equations are solved in some limiting cases of nanoparticle dissolution in dilute suspensions. The obtained kinetic equations were used for the interpretation of experimental data pertinent to the dissolution kinetics of citrate-stabilized silver nanoparticles. In these kinetic measurements the role of pH and bulk suspension concentration was quantitatively evaluated by using the atomic absorption spectrometry (AAS). It was shown that the theoretical model adequately reflects the main features of the experimental results, especially the significant increase in the dissolution rate for lower pH. Also the presence of two kinetic regimes was quantitatively explained in terms of the decrease in the coverage of the fast dissolving oxide layer. The overall silver dissolution rate constants characterizing these two regimes were determined.

  7. Enhanced CO2 Dissolution in Heterogeneous Porous Media

    Science.gov (United States)

    Daniels, K.; Neufeld, J. A.; Bickle, M. J.; Hallworth, M. A.

    2014-12-01

    Long-term and secure geological storage of CO2 through technologies such as Carbon Capture and Storage (CCS) within reservoirs is seen as a technological means to reduce anthropogenic CO2 emissions. The long-term viability of this technology is reliant on the structural and secondary trapping of supercritical CO2 within heterogeneous reservoirs. Secondary trapping, primarily through the dissolution of CO2 into ambient reservoir brine to produce a denser fluid, is capable of retaining CO2 in the subsurface and thus reducing the risks of storage. To model secondary trapping we need to understand how the flow of CO2 through heterogeneous reservoir rocks enhances dissolution of supercritical CO2 in reservoir brines. Here we experimentally investigate the dissolution of CO2 in reservoir brines in layered, heterogeneous geological formations. Using analogue experiments, designed to approximate an enhanced oil recovery (EOR) setting, the processes of mixing, dispersion and dissolution are examined. These are compared against test results from non-layered, homogeneous porous media experiments. We find that heterogeneities significantly enhance mixing, particularly between adjacent porous layers. During fluid propagation, pore-scale viscous fingers grow and retreat, thereby providing an increased surface area between the flow and the ambient reservoir fluid. This enhanced mixing is predicted to substantially increase the dissolution of CO2 in reservoir brines. Both permeability and viscosity differences are found to have a significant effect on the interface between the two fluids, and therefore the likely amount of dissolution of CO2.

  8. Determining the impacts of fermentative bacteria on wollastonite dissolution kinetics.

    Science.gov (United States)

    Salek, S S; Kleerebezem, R; Jonkers, H M; Voncken, J H L; van Loosdrecht, M C M

    2013-03-01

    Silicate minerals can be a source of calcium and alkalinity, enabling CO2 sequestration in the form of carbonates. For this to occur, the mineral needs to be first dissolved in an acidifying process such as the biological process of anaerobic fermentation. In the present study, the main factors which govern the dissolution process of an alkaline silicate mineral (wollastonite, CaSiO3) in an anaerobic fermentation process were determined. Wollastonite dissolution kinetics was measured in a series of chemical batch experiments in order to be able to estimate the required amount of alkaline silicate that can neutralize the acidifying fermentation process. An anaerobic fermentation of glucose with wollastonite as the neutralizing agent was consequently performed in a fed-batch reactor. Results of this experiment were compared with an abiotic (control) fed-batch reactor in which the fermentation products (i.e. organic acids and alcohols) were externally supplied to the system at comparable rates and proportions, in order to provide chemical conditions similar to those during the biotic (fermentation) experiment. This procedure enabled us to determine whether dissolution of wollastonite was solely enhanced by production of organic acids or whether there were other impacts that fermentative bacteria could have on the mineral dissolution rate. The established pH profiles, which were the direct indicator of the dissolution rate, were comparable in both experiments suggesting that the mineral dissolution rate was mostly influenced by the quantity of the organic acids produced.

  9. A geochemical perspective of Red Mountain: an unmined volcanogenic massive sulfide deposit in the Alaska Range

    Science.gov (United States)

    Giles, Stuart A.; Eppinger, Robert G.

    2014-01-01

    The U.S. Geological Survey (USGS) has investigated the environmental geochemistry of a group of unmined volcanogenic massive sulfide (VMS) deposits in the Bonnifield mining district, Alaska Range, east-central Alaska. The spectacularly colored Red Mountain deposit is the best exposed of these and provides excellent baseline geochemical data for natural environmental impacts of acidic rock drainage, metal dissolution and transport, and acidic salt and metal precipitation from an exposed and undisturbed VMS deposit.

  10. DISSOLUTION KINETICS OF KETANSERIN TARTRATE, THE SALT OF A WEAKLY BASIC DRUG

    NARCIS (Netherlands)

    VANDERVEEN, J; BUITENDIJK, HH; LERK, CF

    1992-01-01

    The rotating disc method was used to study the dissolution kinetics of ketanserin tartrate, the salt of a weakly basic drug. Both solubility and dissolution rate decrease exponentially with increasing pH of the dissolution medium. A plot of the logarithm of the ratio of dissolution rate to solubilit

  11. Development and evaluation of methods for starch dissolution using asymmetrical flow field-flow fractionation. Part II: Dissolution of amylose.

    Science.gov (United States)

    Perez-Rea, Daysi; Bergenståhl, Björn; Nilsson, Lars

    2016-02-01

    In this paper, we investigate whether dissolution in water under autoclaving conditions (140 °C, 20 min) or in dimethyl sulfoxide, DMSO (100 °C, 1 h), is preferable for characterization of amylose. Two types of amylose, potato and maize, were dissolved either in water using an autoclave or in DMSO. On the aqueous solutions obtained, the extent of molecular dissolution of the sample (referred to as the dissolution yield) was determined by enzymatic analysis as well as the molecular properties, such as molar mass and root-mean-square radius, obtained with asymmetrical flow field-flow fractionation coupled to multi-angle light scattering and differential refractive index detection (AF4-MALS-dRI). The results showed that both dissolution methods are efficient at dissolving amylose. However, AF4-MALS-dRI analysis revealed substantial differences. Amylose aqueous solutions obtained by dissolution in DMSO were relatively stable over time, but the dissolution method in autoclave caused some degradation of the molecules, and their solutions display a high tendency to retrograde.

  12. Role of surfactant and pH in dissolution of curcumin

    Directory of Open Access Journals (Sweden)

    Rahman SMH

    2009-01-01

    Full Text Available Curcumin is a phytoconstituent with wide range of biological activity. It is poorly soluble in water. In the present study a new dissolution medium was developed, as there is no validated dissolution method available in the literature. The composition of the dissolution medium was selected on the basis of solubility data at 37°. Solubility data revealed that addition of surfactant may be suitable as a dissolution medium. The suitability of dissolution medium (0.5% sodium lauryl sulphate in water relative to the other dissolution medium was evaluated. The selected dissolution media was used for the evaluation of curcumin tablets.

  13. Mechanisms for the removal of calcium phosphate deposits in turbulent flow

    Energy Technology Data Exchange (ETDEWEB)

    Littlejohn, F.; Grant, C.S.; Saez, A.E.

    2000-04-01

    This work investigates the mechanisms for the removal of calcium phosphate deposits from stainless steel tubing in turbulent flows. Two types of deposits were analyzed: brushite (dicalcium phosphate dihydrate, DCPD) and a mixture of DCPD/hydroxyapatite (HAP). Cleaning studies were carried out at pHs ranging from 2.85 to 10. The data were analyzed by means of a mathematical model that incorporates the effects of interfacial dissolution and mass transfer. The results show that the HAP/DCPD cleaning rate is influenced both by the kinetics of the interfacial dissolution and by mass transfer. Within the same range of experimental conditions, the rate-limiting mechanism for DCPD removal was the abrasion of the solid by shear stresses. In this case, the interfacial dissolution process plays the role of decreasing the structural integrity of the deposit. These findings show that the removal mechanism of the HAP/DCPD mixture differs significantly from the behavior of individual components.

  14. Facing Aggression: Cues Differ for Female versus Male Faces

    Science.gov (United States)

    Geniole, Shawn N.; Keyes, Amanda E.; Mondloch, Catherine J.; Carré, Justin M.; McCormick, Cheryl M.

    2012-01-01

    The facial width-to-height ratio (face ratio), is a sexually dimorphic metric associated with actual aggression in men and with observers' judgements of aggression in male faces. Here, we sought to determine if observers' judgements of aggression were associated with the face ratio in female faces. In three studies, participants rated photographs of female and male faces on aggression, femininity, masculinity, attractiveness, and nurturing. In Studies 1 and 2, for female and male faces, judgements of aggression were associated with the face ratio even when other cues in the face related to masculinity were controlled statistically. Nevertheless, correlations between the face ratio and judgements of aggression were smaller for female than for male faces (F1,36 = 7.43, p = 0.01). In Study 1, there was no significant relationship between judgements of femininity and of aggression in female faces. In Study 2, the association between judgements of masculinity and aggression was weaker in female faces than for male faces in Study 1. The weaker association in female faces may be because aggression and masculinity are stereotypically male traits. Thus, in Study 3, observers rated faces on nurturing (a stereotypically female trait) and on femininity. Judgements of nurturing were associated with femininity (positively) and masculinity (negatively) ratings in both female and male faces. In summary, the perception of aggression differs in female versus male faces. The sex difference was not simply because aggression is a gendered construct; the relationships between masculinity/femininity and nurturing were similar for male and female faces even though nurturing is also a gendered construct. Masculinity and femininity ratings are not associated with aggression ratings nor with the face ratio for female faces. In contrast, all four variables are highly inter-correlated in male faces, likely because these cues in male faces serve as “honest signals”. PMID:22276184

  15. Temporal dissolution of potentially toxic elements from silver smelting slag by synthetic environmental solutions.

    Science.gov (United States)

    Ash, Christopher; Borůvka, Luboš; Tejnecký, Václav; Šebek, Ondřej; Nikodem, Antonín; Drábek, Ondřej

    2013-11-15

    Waste slag which is created during precious metal smelting contains high levels of potentially toxic elements (PTE) which can be mobilised from unconfined deposits into the local environment. This paper examines the extractability of selected PTE (Pb, Zn, Cd, Mn) from slag samples by synthetic solutions designed to replicate those in the environment. Extracting agents were used to replicate potential leaching scenarios which are analogous to natural chemical weathering. Slag was submersed in a rainwater simulation solution (RSS), weak citric acid solution (representing rhizosphere secretions) and control solutions (deionised water) for a one month period with solution analyses made at intervals of 1, 24, 168 and 720 h. In 1 mM citric acid, dissolution of Cd and Zn showed little change with time, although for Zn the initial dissolution was considerable. Lead in citric acid was characterized by overall poor extractability. Mn solubility increased until an equilibrium state occurred within 24 h. The solubility of studied metals in citric acid can be characterized by a short time to equilibrium. RSS proved to be an effective solvent that, unlike citric acid solution, extracted increasing concentrations of Cd, Mn and Zn with time. Solubility of Pb in RSS was again very low. When taken as a proportion of a single 2 M HNO3 extraction which was applied to slag samples, Cd was the element most readily leached into RSS and control samples. In both studied solvents, slag heterogeneity is prominent in the case of Cd and Zn solubility. Contact time with solvent appears to be an important variable for the release of PTE from slag into solution. The purpose of this study was to provide insight into the environmental chemical dissolution of PTE from slag, which causes their enrichment in surrounding soils and surface waters.

  16. Facing Sound - Voicing Art

    DEFF Research Database (Denmark)

    Lønstrup, Ansa

    2013-01-01

    This article is based on examples of contemporary audiovisual art, with a special focus on the Tony Oursler exhibition Face to Face at Aarhus Art Museum ARoS in Denmark in March-July 2012. My investigation involves a combination of qualitative interviews with visitors, observations of the audienc......´s interactions with the exhibition and the artwork in the museum space and short analyses of individual works of art based on reception aesthetics and phenomenology and inspired by newer writings on sound, voice and listening....

  17. Dissolution performance of plutonium nitride based fuel materials

    Energy Technology Data Exchange (ETDEWEB)

    Aneheim, E.; Hedberg, M. [Nuclear Chemistry, Chemistry and Chemical Engineering, Chalmers University of Technology, Kemivaegen 4, Gothenburg, SE41296 (Sweden)

    2016-07-01

    Nitride fuels have been regarded as one viable fuel option for Generation IV reactors due to their positive features compared to oxides. To be able to close the fuel cycle and follow the Generation IV concept, nitrides must, however, demonstrate their ability to be reprocessed. This means that the dissolution performance of actinide based nitrides has to be thoroughly investigated and assessed. As the zirconium stabilized nitrides show even better potential as fuel material than does the pure actinide containing nitrides, investigations on the dissolution behavior of both PuN and (Pu,Zr)N has been undertaken. If possible it is desirable to perform the fuel dissolutions using nitric acid. This, as most reprocessing strategies using solvent-solvent extraction are based on a nitride containing aqueous matrix. (Pu,Zr)N/C microspheres were produced using internal gelation. The spheres dissolution performance was investigated using nitric acid with and without additions of HF and Ag(II). In addition PuN fuel pellets were produced from powder and their dissolution performance were also assessed in a nitric acid based setting. It appears that both PuN and (Pu,Zr)N/C fuel material can be completely dissolved in nitric acid of high concentration with the use of catalytic amounts of HF. The amount of HF added strongly affects dissolution kinetics of (Pu, Zr)N and the presence of HF affects the 2 solutes differently, possibly due to inhomogeneity o the initial material. Large additions of Ag(II) can also be used to facilitate the dissolution of (Pu,Zr)N in nitric acid. PuN can be dissolved by pure nitric acid of high concentration at room temperature while (Pu, Zr)N is unaffected under similar conditions. At elevated temperature (reflux), (Pu,Zr)N can, however, also be dissolved by concentrated pure nitric acid.

  18. Conjunction Faces Alter Confidence-Accuracy Relations for Old Faces

    Science.gov (United States)

    Reinitz, Mark Tippens; Loftus, Geoffrey R.

    2017-01-01

    The authors used a state-trace methodology to investigate the informational dimensions used to recognize old and conjunction faces (made by combining parts of separately studied faces). Participants in 3 experiments saw faces presented for 1 s each. They then received a recognition test; faces were presented for varying brief durations and…

  19. Pedagogical Characteristics of Online and Face-to-Face Classes

    Science.gov (United States)

    Wuensch, Karl; Aziz, Shahnaz; Ozan, Erol; Kishore, Masao; Tabrizi, M. H. Nassehzadeh

    2008-01-01

    Currently, many students have had experience with both face-to-face and online classes. We asked such students at 46 different universities in the United States to evaluate the pedagogical characteristics of their most recently completed face-to-face class and their most recently completed online class. The results show that students rate online…

  20. Bayesian Face Recognition and Perceptual Narrowing in Face-Space

    Science.gov (United States)

    Balas, Benjamin

    2012-01-01

    During the first year of life, infants' face recognition abilities are subject to "perceptual narrowing", the end result of which is that observers lose the ability to distinguish previously discriminable faces (e.g. other-race faces) from one another. Perceptual narrowing has been reported for faces of different species and different races, in…

  1. Real Time Face Quality Assessment for Face Log Generation

    DEFF Research Database (Denmark)

    Kamal, Nasrollahi; Moeslund, Thomas B.

    2009-01-01

    Summarizing a long surveillance video to just a few best quality face images of each subject, a face-log, is of great importance in surveillance systems. Face quality assessment is the back-bone for face log generation and improving the quality assessment makes the face logs more reliable....... Developing a real time face quality assessment system using the most important facial features and employing it for face logs generation are the concerns of this paper. Extensive tests using four databases are carried out to validate the usability of the system....

  2. Face recognition system and method using face pattern words and face pattern bytes

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Yufeng

    2014-12-23

    The present invention provides a novel system and method for identifying individuals and for face recognition utilizing facial features for face identification. The system and method of the invention comprise creating facial features or face patterns called face pattern words and face pattern bytes for face identification. The invention also provides for pattern recognitions for identification other than face recognition. The invention further provides a means for identifying individuals based on visible and/or thermal images of those individuals by utilizing computer software implemented by instructions on a computer or computer system and a computer readable medium containing instructions on a computer system for face recognition and identification.

  3. Multibiometrics for face recognition

    NARCIS (Netherlands)

    Veldhuis, Raymond; Deravi, Farzin; Tao, Qian

    2008-01-01

    Fusion is a popular practice to combine multiple sources of biometric information to achieve systems with greater performance and flexibility. In this paper various approaches to fusion within a multibiometrics context are considered and an application to the fusion of 2D and 3D face information is

  4. Multibiometrics for face recognition

    NARCIS (Netherlands)

    Veldhuis, Raymond N.J.; Deravi, Farzin; Tao, Q.

    Fusion is a popular practice to combine multiple sources of biometric information to achieve systems with greater performance and flexibility. In this paper various approaches to fusion within a multibiometrics context are considered and an application to the fusion of 2D and 3D face information is

  5. Two Faces of Japan.

    Science.gov (United States)

    Beasley, Conger, Jr.

    1992-01-01

    Discusses the inconsistency between Japanese exploitation of world natural resources and gestures to provide leadership in ecologically innovative technology. Explores Japanese culture, power structure, population trends, environmental ethics, industrialism, and international business practices as they relate to the philosophical face of…

  6. Bayesian Face Sketch Synthesis.

    Science.gov (United States)

    Wang, Nannan; Gao, Xinbo; Sun, Leiyu; Li, Jie

    2017-03-01

    Exemplar-based face sketch synthesis has been widely applied to both digital entertainment and law enforcement. In this paper, we propose a Bayesian framework for face sketch synthesis, which provides a systematic interpretation for understanding the common properties and intrinsic difference in different methods from the perspective of probabilistic graphical models. The proposed Bayesian framework consists of two parts: the neighbor selection model and the weight computation model. Within the proposed framework, we further propose a Bayesian face sketch synthesis method. The essential rationale behind the proposed Bayesian method is that we take the spatial neighboring constraint between adjacent image patches into consideration for both aforementioned models, while the state-of-the-art methods neglect the constraint either in the neighbor selection model or in the weight computation model. Extensive experiments on the Chinese University of Hong Kong face sketch database demonstrate that the proposed Bayesian method could achieve superior performance compared with the state-of-the-art methods in terms of both subjective perceptions and objective evaluations.

  7. Facing Up to Death

    Science.gov (United States)

    Ross, Elizabeth Kubler

    1972-01-01

    Doctor urges that Americans accept death as a part of life and suggests ways of helping dying patients and their families face reality calmly, with peace. Dying children and their siblings, as well as children's feelings about relatives' deaths, are also discussed. (PD)

  8. Autonomous Face Segmentation

    Science.gov (United States)

    1992-09-01

    and Rhea Diamond. "From Piecemeal to Configurational Repre- sentation of Faces," Science, 195:312-314 (Jan 1977). 3. Damasio , Antonio R...34Prosopagnosia," Trends in Neuroscience, 8:132-135 (1985). 4. Damasio , Antonio R. and others. "Prosopagnosia: Anatomic Basis and Behav- ioral Mechanisms

  9. PrimeFaces blueprints

    CERN Document Server

    Jonna, Sudheer

    2014-01-01

    If you are a Java developer with experience of frontend UI development, and want to take the plunge to develop stunning UI applications with the most popular JSF framework, PrimeFaces, then this book is for you. For those with entrepreneurial aspirations, this book will provide valuable insights into how to utilize successful business models.

  10. Facing Up to Death

    Science.gov (United States)

    Ross, Elizabeth Kubler

    1972-01-01

    Doctor urges that Americans accept death as a part of life and suggests ways of helping dying patients and their families face reality calmly, with peace. Dying children and their siblings, as well as children's feelings about relatives' deaths, are also discussed. (PD)

  11. N2-fixing legumes are linked to enhanced mineral dissolution and microbiome modulations in Neotropical rainforests

    Science.gov (United States)

    Epihov, Dimitar; Batterman, Sarah; Hedin, Lars; Saltonstall, Kristin; Hall, Jefferson; Leake, Jonathan; Beerling, David

    2017-04-01

    Legumes represent the dominant family of many tropical forests with estimates of 120 billion legume trees in the Amazon basin alone. Many rainforest legume trees form symbioses with N2-fixing bacteria. In the process of atmospheric N2-fixation large amounts of nitrogen-rich litter are generated, supplying half of all nitrogen required to support secondary rainforest succession. However, it is unclear how N2-fixers affect the biogeochemical cycling of other essential nutrients by affecting the rates of mineral dissolution and rock weathering. Here we show that N2-fixing legumes in young Panamanian rainforests promote acidification and enhance silicate rock weathering by a factor of 2 compared to non-fixing trees. We report that N2-fixers also associate with enhanced dissolution of Al- and Fe-bearing secondary minerals native to tropical oxisols. In legume-rich neighbourhoods, non-fixers benefited from raised weathering rates relative to those of legume-free zones thus suggesting a positive community effect driven by N2-fixers. These changes in weathering potential were tracked by parallel functional and structural changes in the soil and rock microbiomes. Our findings support the view that N2-fixing legumes are central components of biogeochemical cycling, associated with enhanced release of Fe- and Al-bound P and primary mineral products (Mg, Mo). Rainforest legume services therefore bear important implications to short-term C cycling related to forest growth and the long-term C cycle related to marine carbonate deposition fuelled by silicate weathering.

  12. Differences in physical chemistry and dissolution rate of solid particle aerosols from solution pressurised inhalers.

    Science.gov (United States)

    Buttini, Francesca; Miozzi, Michele; Balducci, Anna Giulia; Royall, Paul G; Brambilla, Gaetano; Colombo, Paolo; Bettini, Ruggero; Forbes, Ben

    2014-04-25

    Solution composition alters the dynamics of beclomethasone diproprionate (BDP) particle formation from droplets emitted by pressurised metered dose inhalers (pMDIs). The hypothesis that differences in inhaler solutions result in different solid particle physical chemistry was tested using a suite of complementary calorimetric techniques. The atomisation of BDP-ethanol solutions from commercial HFA-pMDI produced aerodynamically-equivalent solid particle aerosols. However, differences in particle physico-chemistry (morphology and solvate/clathrate formation) were detected by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and supported by hot stage microscopy (HSM). Increasing the ethanol content of the formulation from 8 to 12% (w/w), which retards the evaporation of propellant and slows the increase in droplet surface viscosity, enhanced the likelihood of particles drying with a smooth surface. The dissolution rate of BDP from the 12% (w/w) ethanol formulation-derived particles (63% dissolved over 120 min) was reduced compared to the 8% (w/w) ethanol formulation-derived particles (86% dissolved over 120 min). The addition of 0.01% (w/w) formoterol fumarate or 1.3% (w/w) glycerol to the inhaler solution modified the particles and reduced the BDP dissolution rate further to 34% and 16% dissolved in 120 min, respectively. These data provide evidence that therapeutic aerosols from apparently similar inhaler products, including those with similar aerodynamic performance, may behave non-equivalently after deposition in the lungs. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Age-Dependent Face Detection and Face Categorization Performance

    OpenAIRE

    Claus-Christian Carbon; Martina Grüter; Thomas Grüter

    2013-01-01

    Empirical studies on the development of face processing skills with age show inconsistent patterns concerning qualitative vs. quantitative changes over time or the age range for peak cognitive performance. In the present study, we tested the proficiency in face detection and face categorization with a large sample of participants (N = 312; age range: 2-88 yrs). As test objects, we used so-called Mooney faces, two-tone (black and white) images of faces lacking critical information of a local, ...

  14. Transient refractory material dissolution by a volumetrically-heated melt

    Energy Technology Data Exchange (ETDEWEB)

    Seiler, Jean Marie, E-mail: jean-marie.seiler@cea.fr [CEA, DEN, DTN, 17 Rue des Martyrs, 38054 Grenoble Cedex 9 (France); Ratel, Gilles [CEA, DEN, DTN, 17 Rue des Martyrs, 38054 Grenoble Cedex 9 (France); Combeau, Hervé [Institut Jean Lamour, UMR 7198, Lorraine University, Ecole des Mines de Nancy, Parc de Saurupt, 54042 Nancy Cedex (France); Gaus-Liu, Xiaoyang; Kretzschmar, Frank; Miassoedov, Alexei [Karlsruhe Institut of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2014-12-15

    Highlights: • We describe a test investigating ceramic dissolution by a molten non-eutectic melt. • The evolution of the interface temperature between melt and refractory is measured. • A theoretical model describing dissolution kinetics is proposed. • When dissolution stops, interface temperature is the liquidus temperature of the melt. - Abstract: The present work addresses the question of corium–ceramic interaction in a core catcher during a core-melt accident in a nuclear power plant. It provides an original insight into transient aspects concerning dissolution of refractory material by a volumetrically heated pool. An experiment with simulant material (LIVECERAM) is presented. Test results clearly show that dissolution of solid refractory material can occur in a non-eutectic melt at a temperature which is lower than the melting temperature of the refractory material. During the dissolution transient, the interface temperature rises above the liquidus temperature, corresponding to the instantaneous average composition of the melt pool. With constant power dissipation in the melt and external cooling of the core-catcher, a final steady-state situation is reached. Dissolution stops when the heat flux (delivered by the melt to the refractory) can be removed by conduction through the residual thickness of the ceramic, with T{sub interface} = T{sub liquidus} (calculated for the average composition of the final liquid pool). The final steady state corresponds to a uniform pool composition and uniform interface temperature distribution. Convection in the pool is governed by natural thermal convection and the heat flux distribution is therefore similar to what would be obtained for a single component pool. An interpretation of the experiment with two model-based approaches (0D and 1D) is presented. The mass transfer kinetics between the interface and the bulk is controlled by a diffusion sublayer within the boundary layer. During the dissolution transient

  15. Rates and mechanisms of uranyl oxyhydroxide mineral dissolution

    Science.gov (United States)

    Reinoso-Maset, Estela; Steefel, Carl I.; Um, Wooyong; Chorover, Jon; O'Day, Peggy A.

    2017-06-01

    Uranyl oxyhydroxide minerals are important weathering products in uranium-contaminated surface and subsurface environments that regulate dissolved uranium (U) concentrations. However, dissolution rates for this class of minerals and associated dissolution mechanisms have not been previously reported for circumneutral pH conditions, particularly for the case of flow through porous media. In this work, the dissolution rates of K- and Na-compreignacite (K2(UO2)6O4(OH)6·8H2O and Na2(UO2)6O4(OH)6·8H2O, respectively) were measured using flow-through columns reacted with two simulated background porewater (BPW) solutions of low and high dissolved carbonate concentration (ca. 0.2 and 2.8 mmol L-1). Column materials were characterized before and after reaction with electron microscopy, bulk chemistry, and EXAFS to identify structural and chemical changes during dissolution and to obtain insight into molecular-scale processes. The reactive transport code CrunchFlow was used to calculate overall dissolution rates while accounting for fluid transport and changes in mineral volume and reactive surface area, and results were compared to steady-state dissolution rate calculations. In low carbonate BPW systems, interlayer K and Na were initially leached from both minerals, and in Na-compreignacite, K and minor divalent cations from the input solution were incorporated into the mineral structure. Results of characterization analyses suggested that after reaction both K- and Na-compreignacite resembled a disordered K-compreignacite with altered surfaces. A 10-fold increase in dissolved carbonate concentration and corresponding increase in pH (from 6.65 to 8.40) resulted in a net removal of 58-87% of total U mass from the columns, compared to mass removal during dissolution more accurately reproduced effluent data in high carbonate systems, and resulted in faster overall rates compared with a steady-state dissolution assumption. This study highlights the importance of coupling

  16. METALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>20122389 Cai Lianyou ( No.332 Geological Team,Bureau of Geology and Mineral Resources Exploration of Anhui Province,Huangshan 245000,China );Weng Wangfei Geologic Characteristic and Ore-Control Factors of the Nanshan W-Mo Polymetallic Ore Deposit in South Anhui Province ( Geological Survey and Research,ISSN1672-4135,CN12-1353 / P,34 ( 4 ), 2011,p.290-298,3 illus.,1table,14refs. ) Key words:tungsten ores,molybdenum ores,ore guide of prospecting,Anhui Province

  17. METALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>20110165 Chen Jiawei(The 3rd Geological Team,Henan Bureau of Geology and Mineral Resources,Xinyang 464000,China)Ore Control Conditions and Genetic Model for the Bodaoling Ag-Au Deposit in Guangshan,Henan Province(Acta Geologica Sichuan,ISSN1006-0995,CN51-1273/P,30(1),2010,p.28-30,5 illus.,1 ref.,with English abstract)Key words:gold ores,Henan Province20110166 Chen Mingquan(Geological Team 306,Yunnan Bureau of Nonferrous Geology,Kunming 650216,Ch

  18. Kinetics of dissolution of calcium phosphate (Ca-P bioceramics

    Directory of Open Access Journals (Sweden)

    Lukas Brazda

    2008-06-01

    Full Text Available Hydroxyapatite (HAp and β-tricalcium phosphate (β-TCP are widely used bioceramics for surgical or dental applications. This paper is dealing with dissolution kinetics of synthetically prepared β-TCP and four types of HAp granules. Two groups of HAp, treated at different temperatures, each of them with two different granule sizes, were tested. Three corrosive solutions with different pH and simulated body fluid (SBF were used for immersing of the samples. Changes in concentrations of calcium and phosphate ions, pH level and weight changes of the samples were observed. It was found that presence of TRIS buffer enhanced dissolution rate of the β-TCP approximately two times. When exposed to SBF solution, calcium phosphate (most probably hydroxyapatite precipitation predominates over β-TCP dissolution. Results from HAp samples dissolution showed some unexpected findings. Neither heat treatment nor HAp particle size made any major differences in dissolution rate of the same mass of each HAp sample.

  19. How good is cola for dissolution of gastric phytobezoars?

    Institute of Scientific and Technical Information of China (English)

    Beom Jae Lee; Jong-Jae Park; Hoon Jai Chun; Ji Hoon Kim; Jong Eun Yeon; Yoon Tae Jeen; Jae Seon Kim; Kwan Soo Byun; Sang Woo Lee; Jae Hyun Choi; Chang Duck Kim; Ho Sang Ryu; Young-Tae Bak

    2009-01-01

    AIM: To evaluate the efficacy of cola treatment for gastric phytobezoars, including diospyrobezoars. METHODS: A total of 17 patients (range: 48 to 78 years) with symptomatic gastric phytobezoars treated with cola and adjuvant endoscopic therapy were reviewed. Three liters of cola lavage (10 cases) or drink (7 cases) were initially used, and then endoscopic fragmentation was done for the remnant bezoars by using a lithotripsy basket or a polypectomy snare. The overall success of dissolving a gastric phytobezoars with using three liters of cola and the clinical and endoscopic findings were compared retrospectively between four cases of complete dissolution by using only cola and 13 cases of partial dissolution with cola. RESULTS: After 3 L of cola lavage or drinking, a complete dissolution of bezoars was achieved in four patients (23.5%), while 13 cases (76.5%) were only partially dissolved. Phytobezoars (4 of 6 cases) were observed more frequently than diospyrobezoars (0 of 11) in the group that underwent complete dissolution ( P = 0.006). Gender, symptom duration, size of bezoar and method of cola administration were not significantly different between the two groups. Twelve of 13 patients with residual bezoars were completely treated with a combination of cola and endoscopic fragmentation. CONCLUSION: The rate of complete dissolution with three liters of cola was 23.5%, but no case of diospyrobezoar was completely dissolved using this method. However, pretreatment with cola may be helpful and facilitate endoscopic fragmentation of gastric phytobezoars.

  20. Roche volume filling and the dissolution of open star clusters

    CERN Document Server

    Ernst, A; Just, A; Noel, T

    2015-01-01

    From direct N-body simulations we find that the dynamical evolution of star clusters is strongly influenced by the Roche volume filling factor. We present a parameter study of the dissolution of open star clusters with different Roche volume filling factors and different particle numbers. We study both Roche volume underfilling and overfilling models and compare with the Roche volume filling case. We find that in the Roche volume overfilling limit of our simulations two-body relaxation is no longer the dominant dissolution mechanism but the changing cluster potential. We call this mechnism "mass-loss driven dissolution" in contrast to "two-body relaxation driven dissolution" which occurs in the Roche volume underfilling regime. We have measured scaling exponents of the dissolution time with the two-body relaxation time. In this experimental study we find a decreasing scaling exponent with increasing Roche volume filling factor. The evolution of the escaper number in the Roche volume overfilling limit can be d...

  1. The Baltimore and Utrecht models for cluster dissolution

    CERN Document Server

    Lamers, Henny J G L M

    2008-01-01

    The analysis of the age distributions of star cluster samples of different galaxies has resulted in two very different empirical models for the dissolution of star clusters: the Baltimore model and the Utrecht model. I describe these two models and their differences. The Baltimore model implies that the dissolution of star clusters is mass independent and that about 90% of the clusters are destroyed each age dex, up to an age of about a Gyr, after which point mass-dependent dissolution from two-body relaxation becomes the dominant mechanism. In the Utrecht model, cluster dissolution occurs in three stages: (i) mass-independent infant mortality due to the expulsion of gas up to about 10 Myr; (ii) a phase of slow dynamical evolution with strong evolutionary fading of the clusters lasting up to about a Gyr; and (iii) a phase dominated by mass dependent-dissolution, as predicted by dynamical models. I describe the cluster age distributions for mass-limited and magnitude-limited cluster samples for both models. I ...

  2. Dissolution enhancement of aceclofenac tablet by solid dispersion technique

    Directory of Open Access Journals (Sweden)

    Kiroj Rajbanshi

    2014-04-01

    Full Text Available Present study was carried out to enhace the dissolution rate of poorly water soluble drug Aceclofenac (BCS –II, by solid dispersion technique using different carrier and super disintegrant by Kneading method. Screening of carrier and super disintegrant having better dissolution effect was performed by Placket Burman Design. Carrier that were selected for the study include Hydroxypropyl Beta Cyclodextrin (HPBCD, premix of Lactose and Maize Starch and Mannitol. Similarly, as superdisintegrant, Sodium Starch Glycolate (SSG, Croscarmellose and Crospovidone were selected . Among the carriers and superdisintegrants, Mannitol and Crospovidone showed best effect on dissolution, respectively. For optimizaton of concentration of Mannitol and Crospovidone in solid dispersion, Central Composite Design (CCD was applied for two factor at two level which gave 13 formulation.Tablet were prepared and evaluated for physiochemical properties. Reponse surface plot and contour plot were drawn and an optimum formulation was selected, which contained 114.14 mg of Mannitol and 10.5 mg of Crospovidone. The in-vitro dissolution studies of optimized formulation CCDF8 and the marketed product were carried out in USP Type II apparatus at different time interval of 5,15, 30 and 45 minute at 50 rpm in phosphate buffer, pH 7.5 (0.33M mixed. Solid dispersion was evaluated by FTIR. It showed that the drug was stable in solid dispersion. Hence, Solid dispersion technique can be sucessfully used for the improvement of the dissolution profile of Aceclofenac.

  3. Exogenous attention during perceptual group formation and dissolution.

    Science.gov (United States)

    Gonen, Fahrettin F; Ogmen, Haluk

    2017-02-01

    Under natural viewing conditions, a large amount of information reaches our senses, and the visual system uses attention and perceptual grouping to reduce the complexity of stimuli in order to make real-time perception possible. Prior studies have shown that attention and perceptual grouping operate in synergy; exogenous attention is deployed not only to the cued item, but also to the entire group. Here, we investigated how attention and perceptual grouping operate during the formation and dissolution of groups. Our results showed that reaction times are higher in the presence of perceptual groups than they are for ungrouped stimuli. On the other hand, attentional benefits of perceptual grouping were observed during both the formation and the dissolution of groups. The dynamics were similar during group formation and dissolution, showing a gradual effect that takes approximately half a second to reach its maximum level. In the case of group dissolution, the attentional benefits persisted for about a quarter of a second after dissolution of the group. Taken together, our results reveal the dynamics of how attention and grouping work in synergy during the transient period when groups form or dissolve.

  4. Roche volume filling and the dissolution of open star clusters

    Science.gov (United States)

    Ernst, A.; Berczik, P.; Just, A.; Noel, T.

    2015-08-01

    From direct N-body simulations we find that the dynamical evolution of star clusters is strongly influenced by the Roche volume filling factor. We present a parameter study of the dissolution of open star clusters with different Roche volume filling factors and different particle numbers. We study both Roche volume underfilling and overfilling models and compare with the Roche volume filling case. We find that in the Roche volume overfilling limit of our simulations two-body relaxation is no longer the dominant dissolution mechanism but the changing cluster potential. We call this mechanism ``mass-loss driven dissolution'' in contrast to ``two-body relaxation driven dissolution'' which occurs in the Roche volume underfilling regime. We have measured scaling exponents of the dissolution time with the two-body relaxation time. In this experimental study we find a decreasing scaling exponent with increasing Roche volume filling factor. The evolution of the escaper number in the Roche volume overfilling limit can be described by a log-logistic differential equation. We report the finding of a resonance condition which may play a role for the evolution of star clusters and may be calibrated by the main periodic orbit in the large island of retrograde quasiperiodic orbits in the Poincaré surfaces of section. We also report on the existence of a stability curve which may be of relevance with respect to the structure of star clusters.

  5. Computational fluid dynamics (CFD) studies of a miniaturized dissolution system.

    Science.gov (United States)

    Frenning, G; Ahnfelt, E; Sjögren, E; Lennernäs, H

    2017-02-08

    Dissolution testing is an important tool that has applications ranging from fundamental studies of drug-release mechanisms to quality control of the final product. The rate of release of the drug from the delivery system is known to be affected by hydrodynamics. In this study we used computational fluid dynamics to simulate and investigate the hydrodynamics in a novel miniaturized dissolution method for parenteral formulations. The dissolution method is based on a rotating disc system and uses a rotating sample reservoir which is separated from the remaining dissolution medium by a nylon screen. Sample reservoirs of two sizes were investigated (SR6 and SR8) and the hydrodynamic studies were performed at rotation rates of 100, 200 and 400rpm. The overall fluid flow was similar for all investigated cases, with a lateral upward spiraling motion and central downward motion in the form of a vortex to and through the screen. The simulations indicated that the exchange of dissolution medium between the sample reservoir and the remaining release medium was rapid for typical screens, for which almost complete mixing would be expected to occur within less than one minute at 400rpm. The local hydrodynamic conditions in the sample reservoirs depended on their size; SR8 appeared to be relatively more affected than SR6 by the resistance to liquid flow resulting from the screen.

  6. Dissolution of hematite nanoparticle aggregates: influence of primary particle size, dissolution mechanism, and solution pH.

    Science.gov (United States)

    Lanzl, Caylyn A; Baltrusaitis, Jonas; Cwiertny, David M

    2012-11-13

    The size-dependent dissolution of nanoscale hematite (8 and 40 nm α-Fe(2)O(3)) was examined across a broad range of pH (pH 1-7) and mechanisms including proton- and ligand- (oxalate-) promoted dissolution and dark (ascorbic acid) and photochemical (oxalate) reductive dissolution. Empirical relationships between dissolution rate and pH revealed that suspensions of 8 nm hematite exhibit between 3.3- and 10-fold greater reactivity per unit mass than suspensions of 40 nm particles across all dissolution modes and pH, including circumneutral. Complementary suspension characterization (i.e., sedimentation studies and dynamic light scattering) indicated extensive aggregation, with steady-state aggregate sizes increasing with pH but being roughly equivalent for both primary particles. Thus, while the reactivity difference between 8 and 40 nm suspensions is generally greater than expected from specific surface areas measured via N(2)-BET or estimated from primary particle geometry, loss of reactive surface area during aggregation limits the certainty of such comparisons. We propose that the relative reactivity of 8 and 40 nm hematite suspensions is best explained by differences in the fraction of aggregate surface area that is reactive. This scenario is consistent with TEM images revealing uniform dissolution of aggregated 8 nm particles, whereas 40 nm particles within aggregates undergo preferential etching at edges and structural defects. Ultimately, we show that comparably sized hematite aggregates can exhibit vastly different dissolution activity depending on the nature of the primary nanoparticles from which they are constructed, a result with wide-ranging implications for iron redox cycling.

  7. Combinatorial localized dissolution analysis: Application to acid-induced dissolution of dental enamel and the effect of surface treatments.

    Science.gov (United States)

    Parker, Alexander S; Al Botros, Rehab; Kinnear, Sophie L; Snowden, Michael E; McKelvey, Kim; Ashcroft, Alexander T; Carvell, Mel; Joiner, Andrew; Peruffo, Massimo; Philpotts, Carol; Unwin, Patrick R

    2016-08-15

    A combination of scanning electrochemical cell microscopy (SECCM) and atomic force microscopy (AFM) is used to quantitatively study the acid-induced dissolution of dental enamel. A micron-scale liquid meniscus formed at the end of a dual barrelled pipette, which constitutes the SECCM probe, is brought into contact with the enamel surface for a defined period. Dissolution occurs at the interface of the meniscus and the enamel surface, under conditions of well-defined mass transport, creating etch pits that are then analysed via AFM. This technique is applied to bovine dental enamel, and the effect of various treatments of the enamel surface on acid dissolution (1mM HNO3) is studied. The treatments investigated are zinc ions, fluoride ions and the two combined. A finite element method (FEM) simulation of SECCM mass transport and interfacial reactivity, allows the intrinsic rate constant for acid-induced dissolution to be quantitatively determined. The dissolution of enamel, in terms of Ca(2+) flux ( [Formula: see text] ), is first order with respect to the interfacial proton concentration and given by the following rate law: [Formula: see text] , with k0=0.099±0.008cms(-1). Treating the enamel with either fluoride or zinc ions slows the dissolution rate, although in this model system the partly protective barrier only extends around 10-20nm into the enamel surface, so that after a period of a few seconds dissolution of modified surfaces tends towards that of native enamel. A combination of both treatments exhibits the greatest protection to the enamel surface, but the effect is again transient.

  8. Formalization of the kinetics for autocatalytic dissolutions. Focus on the dissolution of uranium dioxide in nitric medium

    Directory of Open Access Journals (Sweden)

    Charlier Florence

    2017-01-01

    Full Text Available Uranium dioxide dissolution in nitric acid is a complex reaction. On the one hand, the dissolution produces nitrous oxides (NOX, which makes it a triphasic reaction. On the other hand, one of the products accelerates the kinetic rate; the reaction is hence called autocatalytic. The kinetics for these kinds of reactions need to be formalized in order to optimize and design innovative dissolution reactors. In this work, the kinetics rates have been measured by optical microscopy using a single particle approach. The advantages of this analytical technique are an easier management of species transport in solution and a precise following of the dissolution rate. The global rate is well described by a mechanism considering two steps: a non-catalyzed reaction, where the catalyst concentration has no influence on the dissolution rate, and a catalyzed reaction. The mass transfer rate of the catalyst was quantified in order to discriminate when the reaction was influenced by catalyst accumulated in the boundary layer or uncatalyzed. This first approximation described well the sigmoid dissolution curve profile. Moreover, experiments showed that solutions filled with catalyst proved to lose reactivity over time. Results pointed out that the higher the liquid-gas exchanges, the faster the kinetic rate decreases with time. Thus, it was demonstrated, for the first time, that there is a link between catalyst and nitrous oxides. The outcome of this study leads to new ways for improving the design of dissolvers. Gas-liquid exchanges are indeed a lever to impact dissolution rates. Temperature and catalyst concentration can be optimized to reduce residence times in dissolvers.

  9. Face aftereffects predict individual differences in face recognition ability.

    Science.gov (United States)

    Dennett, Hugh W; McKone, Elinor; Edwards, Mark; Susilo, Tirta

    2012-01-01

    Face aftereffects are widely studied on the assumption that they provide a useful tool for investigating face-space coding of identity. However, a long-standing issue concerns the extent to which face aftereffects originate in face-level processes as opposed to earlier stages of visual processing. For example, some recent studies failed to find atypical face aftereffects in individuals with clinically poor face recognition. We show that in individuals within the normal range of face recognition abilities, there is an association between face memory ability and a figural face aftereffect that is argued to reflect the steepness of broadband-opponent neural response functions in underlying face-space. We further show that this correlation arises from face-level processing, by reporting results of tests of nonface memory and nonface aftereffects. We conclude that face aftereffects can tap high-level face-space, and that face-space coding differs in quality between individuals and contributes to face recognition ability.

  10. Physico-chemical study of coating plasma duplex alumina/hydroxyapatite for medical applications relation elaboration/structure/properties(dissolution/adherence/residual constraints); Etude physico-chimique de depots plasma duplex alumine/hydroxyapatite pour applications medicales relations elaboration/structure/proprietes (dissolution/adherence/contraintes residuelles)

    Energy Technology Data Exchange (ETDEWEB)

    Demonet, N

    1998-11-19

    The physico-chemical behavior of porous ceramics depositing is studied in order to use them to favour the biological fixing of hip prosthesis fixed without cement. Alumina depositing, hydroxyapatite depositing and duplex (the both together) have been realized by plasma projection on a substrate in Ti-6Al-V. Tests of dissolution have been made. An original method of sound followed by radioactive tracers has allowed to establish an order of phases degradation and to consider the kinetics of calcium ions in function of several parameters of tests. (N.C.)

  11. Human faces are slower than chimpanzee faces.

    Directory of Open Access Journals (Sweden)

    Anne M Burrows

    Full Text Available BACKGROUND: While humans (like other primates communicate with facial expressions, the evolution of speech added a new function to the facial muscles (facial expression muscles. The evolution of speech required the development of a coordinated action between visual (movement of the lips and auditory signals in a rhythmic fashion to produce "visemes" (visual movements of the lips that correspond to specific sounds. Visemes depend upon facial muscles to regulate shape of the lips, which themselves act as speech articulators. This movement necessitates a more controlled, sustained muscle contraction than that produced during spontaneous facial expressions which occur rapidly and last only a short period of time. Recently, it was found that human tongue musculature contains a higher proportion of slow-twitch myosin fibers than in rhesus macaques, which is related to the slower, more controlled movements of the human tongue in the production of speech. Are there similar unique, evolutionary physiologic biases found in human facial musculature related to the evolution of speech? METHODOLOGY/PRINICIPAL FINDINGS: Using myosin immunohistochemistry, we tested the hypothesis that human facial musculature has a higher percentage of slow-twitch myosin fibers relative to chimpanzees (Pan troglodytes and rhesus macaques (Macaca mulatta. We sampled the orbicularis oris and zygomaticus major muscles from three cadavers of each species and compared proportions of fiber-types. Results confirmed our hypothesis: humans had the highest proportion of slow-twitch myosin fibers while chimpanzees had the highest proportion of fast-twitch fibers. CONCLUSIONS/SIGNIFICANCE: These findings demonstrate that the human face is slower than that of rhesus macaques and our closest living relative, the chimpanzee. They also support the assertion that human facial musculature and speech co-evolved. Further, these results suggest a unique set of evolutionary selective pressures on

  12. Mineral precipitation and dissolution at two slag-disposal sites in northwestern Indiana, USA

    Science.gov (United States)

    Bayless, E.R.; Schulz, M.S.

    2003-01-01

    Slag is a ubiquitous byproduct of the iron- and steel-refining industries. In northwestern Indiana and northeastern Illinois, slag has been deposited over more than 52 km2 of land surface. Despite the widespread use of slag for fill and construction purposes, little is known about its chemical effects on the environment. Two slagdisposal sites were examined in northwestern Indiana where slag was deposited over the native glacial deposits. At a third site, where slag was not present, background conditions were defined. Samples were collected from cores and drill cuttings and described with scanning electron microscopy and electron microprobe analysis. Ground-water samples were collected and used to assess thermodynamic equilibria between authigenic minerals and existing conditions. Differences in the mineralogy at background and slag-affected sites were apparent. Calcite, dolomite, gypsum, iron oxides, and clay minerals were abundant in native sediments immediately beneath the slag. Mineral features indicated that these minerals precipitated rapidly from slag drainage and co-precipitated minor amounts of non-calcium metals and trace elements. Quartz fragments immediately beneath the slag showed extensive pitting that was not apparent in sediments from the background site, indicating chemical weathering by the hyperalkaline slag drainage. The environmental impacts of slag-related mineral precipitation include disruption of natural ground-water flow patterns and bed-sediment armoring in adjacent surface-water systems. Dissolution of native quartz by the hyperalkaline drainage may cause instability in structures situated over slag fill or in roadways comprised of slag aggregates.

  13. The potential for metal release by reductive dissolution of weathered mine tailings

    Science.gov (United States)

    Ribeta, I.; Ptacek, C. J.; Blowes, D. W.; Jambor, J. L.

    1995-01-01

    Remediation programs proposed for decommissioned sulphide tailings may include the addition of a cover layer rich in organic-carbon material such as sewage sludge or composted municipal waste. These covers are designed to consume oxygen and prevent the oxidation of underlying sulphide minerals. The aerobic and anaerobic degradation of such organic-carbon-rich waste can release soluble organic compounds to infiltrating precipitation water. In laboratory experiments, and in natural settings, biotic and abiotic interactions between similar dissolved organic compounds and ferric-bearing secondary minerals have been observed to result in the reductive dissolution of ferric (oxy)hydroxides and the release of ferrous iron to pore waters. In weathered tailings, oxidation of sulphide minerals typically results in the formation of abundant ferric-bearing secondary precipitates near the tailings surface. These secondary precipitates may contain high concentrations of potentially toxic metals, either coprecipitated with or adsorbed onto ferric (oxy)hydroxides. Reductive dissolution reactions, resulting from the addition of the organic-carbon covers, may remobilize metals previously attenuated near the tailings surface. To assess the potential for metal release to tailings pore water by reductive dissolution reactions, a laboratory study was conducted on weathered tailings collected from the Nickel Rim mine tailings impoundment near Sudbury, Ontario, Canada. This site was selected for study because it is representative of many tailings sites. Mineralogical study indicates that sulphide minerals originally present in the vadose zone at the time of tailings deposition have been replaced by a series of secondary precipitates. The most abundant secondary minerals are goethite, gypsum and jarosite. Scanning electron microscopy, coupled with elemental analyses by X-ray energy dispersion analysis, and electron microprobe analysis indicate that trace metals including Ni, Cr and Cu are

  14. High Level Waste System Impacts from Acid Dissolution of Sludge

    Energy Technology Data Exchange (ETDEWEB)

    KETUSKY, EDWARD

    2006-04-20

    This research evaluates the ability of OLI{copyright} equilibrium based software to forecast Savannah River Site High Level Waste system impacts from oxalic acid dissolution of Tank 1-15 sludge heels. Without further laboratory and field testing, only the use of oxalic acid can be considered plausible to support sludge heel dissolution on multiple tanks. Using OLI{copyright} and available test results, a dissolution model is constructed and validated. Material and energy balances, coupled with the model, identify potential safety concerns. Overpressurization and overheating are shown to be unlikely. Corrosion induced hydrogen could, however, overwhelm the tank ventilation. While pH adjustment can restore the minimal hydrogen generation, resultant precipitates will notably increase the sludge volume. OLI{copyright} is used to develop a flowsheet such that additional sludge vitrification canisters and other negative system impacts are minimized. Sensitivity analyses are used to assess the processability impacts from variations in the sludge/quantities of acids.

  15. Characteristics of MOX dissolution with silver mediated electrolytic oxidation method

    Energy Technology Data Exchange (ETDEWEB)

    Umeda, Miki; Nakazaki, Masato; Kida, Takashi; Sato, Kenji; Kato, Tadahito; Kihara, Takehiro; Sugikawa, Susumu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-03-01

    MOX dissolution with silver mediated electrolytic oxidation method is to be applied to the preparation of plutonium nitrate solution to be used for criticality safety experiments at Nuclear Fuel Cycle Safety Engineering Research Facility (NUCEF). Silver mediated electrolytic oxidation method uses the strong oxidisation ability of Ag(II) ion. This method is though to be effective for the dissolution of MOX, which is difficult to be dissolved with nitric acid. In this paper, the results of experiments on dissolution with 100 g of MOX are described. It was confirmed from the results that the MOX powder to be used at NUCEF was completely dissolved by silver mediated electrolytic oxidation method and that Pu(VI) ion in the obtained solution was reduced to tetravalent by means of NO{sub 2} purging. (author)

  16. Instabilities in the dissolution of a porous matrix

    CERN Document Server

    Szymczak, Piotr; 10.1029/2011GL046720

    2011-01-01

    A reactive fluid dissolving the surrounding rock matrix can trigger an instability in the dissolution front, leading to spontaneous formation of pronounced channels or wormholes. Theoretical investigations of this instability have typically focused on a steadily propagating dissolution front that separates regions of high and low porosity. In this paper we show that this is not the only possible dissolutional instability in porous rocks; there is another instability that operates instantaneously on any initial porosity field, including an entirely uniform one. The relative importance of the two mechanisms depends on the ratio of the porosity increase to the initial porosity. We show that the "inlet" instability is likely to be important in limestone formations where the initial porosity is small and there is the possibility of a large increase in permeability. In quartz-rich sandstones, where the proportion of easily soluble material (e.g. carbonate cements) is small, the instability in the steady-state equat...

  17. Stick-jump mode in surface droplet dissolution

    CERN Document Server

    Dietrich, Erik; Zhang, Xuehua; Zandvliet, Harold J W; Lohse, Detlef

    2016-01-01

    The analogy between evaporating surface droplets in air to dissolving long-chain alcohol droplets in water is worked out. We show that next to the three known modi for surface droplet evaporation or dissolution (constant contact angle mode, constant contact radius mode, and stick-slide mode), a fourth mode exists for small droplets on supposedly smooth substrates, namely the stick-jump mode: intermittent contact line pinning causes the droplet to switch between sticking and jumping during the dissolution. We present experimental data and compare them to theory to predict the dissolution time in this stick-jump mode. We also explain why these jumps were easily observed for microscale droplets but not for larger droplets.

  18. Interactions between ciprofloxacin and antacids--dissolution and adsorption studies.

    Science.gov (United States)

    Arayne, M Saeed; Sultana, Najma; Hussain, Fida

    2005-01-01

    Ciprofloxacin is a fluorinated quinolone antibacterial agent extensively used against both Gram-positive and Gram-negative microorganisms. In certain polytherapy programs, ciprofloxacin can be administered with some antacids that could modify its dissolution rate and reduce its absorption leading to therapeutic failure. The aim of this study was to evaluate the influence of some antacids on the availability of ciprofloxacin. The release of ciprofloxacin from tablets in the presence of antacids, such as sodium bicarbonate, calcium hydroxide, calcium carbonate, aluminum hydroxide, magnesium hydroxide, magnesium carbonate, magnesium trisilicate and magaldrate was studied on BP 2002 dissolution test apparatus. These studies were carried out in simulated gastric and intestinal juices for 3 hours at 37 degrees C. The results confirmed that the dissolution rate of tablets was markedly retarded in the presence of all the antacids studied. Magaldrate and calcium carbonate in simulated gastric juice exhibited relatively higher adsorption capacities, as did magnesium trisilicate and calcium hydroxide in simulated intestinal juice.

  19. The effect of sentencing types on singlehood and relationship dissolution

    DEFF Research Database (Denmark)

    Fallesen, Peter; Andersen, Lars Højsgaard

    Prior research shows that imprisonment may matter for the risk of experiencing divorce or other types of relationship dissolution, as imprisonment implies separation and the social stigma of criminal conviction. Despite these straightforward theoretical mechanisms, we currently lack empirical...... knowledge on the causal effect of sentencing types on relationship dissolution. This study fills this gap in the literature by examining how a noncustodial alternatives to imprisonment—electronic monitoring—affects the risk of relationship dissolution in Denmark. While imprisonment might disrupt contacts...... between spouses or partners, and restrains single convicted men from interacted with other for significant periods, electronic monitoring allows felons to serve time without severing ties to their partner and community. To obtain uncontaminated estimates of the effect of sentencing types on relationship...

  20. Dissolution of a Colloidal Particle in an Oscillatory Fluid Medium

    Science.gov (United States)

    Ye, Dezhuang; Li, Ji-Qin; Bogner, Robin; Fan, Tai-Hsi

    Understanding dissolution kinetics of a colloidal particle in an aqueous solution is of great importance in many pharmaceutical and biochemical applications. We present theoretical analysis of low Reynolds number transient dynamics and mass transfer of a dissolving spherical particle in a unidirectional oscillatory flow. The coupling of fluid flow and passive motion of the particle are resolved analytically, and the transient mass transfer associated with the oscillation of the particle is numerically computed. The flow patterns, diffusive and convective transport phenomena, and the dissolution kinetics under various saturation concentrations and flow conditions are characterized by the frequency parameter, Schmidt number, and Peclet number. The result severs as a basic case in determining the efficiency of drug dissolution or reconstitution that depends on various shaking methods.

  1. Comparative evaluation of methods to quantify dissolution of nanomaterials

    DEFF Research Database (Denmark)

    Hartmann, Nanna B.; Kruse, Susanne; Baun, Anders

    2015-01-01

    dissolved concentration or by the solubility constant (Ksp). For nanomaterials it is essential to also assess solubility kinetics as nanomaterials will often not dissolve instantaneously upon contact with artificial aqueous media or natural waters. Dissolution kinetics will thereby influence their short...... and long-term environmental fate as well as laboratory test results. This highlights the need to evaluate and improve the reliability of methods applied to assess the solubility kinetics of nanomaterials. Based on existing OECD guidelines and guidance documents on aqueous dissolution of metals and metal....... Preliminary results showed that by using the DGT method the measured dissolved fraction was 5-7 times higher compared to using ultracentrifugation and dialysis membranes. Possible explanations include metal-specific interactions with the dialysis membranes as well as the DGT unit influencing the dissolution...

  2. Simulation of dissolution in porous media in three dimensions with lattice Boltzmann, finite-volume, and surface-rescaling methods

    Science.gov (United States)

    Gray, F.; Cen, J.; Boek, E. S.

    2016-10-01

    We present a pore-scale dissolution model for the simulation of reactive transport in complex porous media such as those encountered in carbon-storage injection processes. We couple a lattice Boltzmann model for flow calculation with a finite-volume method for solving chemical transport equations, and allow the computational grid to change as mineral surfaces are dissolved according to first-order reaction kinetics. We appraise this scheme for use with high Péclet number flows in three-dimensional geometries and show how the popular first-order convection scheme is affected by severe numerical diffusion when grid Péclet numbers exceed unity, and confirm that this can be overcome relatively easily by using a second-order method in conjunction with a flux-limiter function. We then propose a surface rescaling method which uses parabolic elements to counteract errors in surface area exposed by the Cartesian grid and avoid the use of more complex embedded surface methods when surface reaction kinetics are incorporated. Finally, we compute dissolution in an image of a real porous limestone rock sample injected with HCl for different Péclet numbers and obtain dissolution patterns in concordance with theory and experimental observation. A low injection flow rate was shown to lead to erosion of the pore space concentrated at the face of the rock, whereas a high flow rate leads to wormhole formation.

  3. Impact of halite dissolution subsidence on Quaternary fluvial terrace development: Case study of the Huerva River, Ebro Basin, NE Spain

    Science.gov (United States)

    Guerrero, Jesús; Gutiérrez, Francisco; Lucha, Pedro

    2008-08-01

    This paper analyses the control of evaporite dissolution subsidence on the evolution of the lower 30 km-long reach of the Huerva River up to its confluence with the Ebro River. In the study area the Huerva River flows across different interfingered lithofacies of the subhorizontally lying Ebro Basin fill: (1) shales and sandstones upstream of Cadrete; (2) evaporites dominated by gypsum between Cadrete and Cuarte; (3) gypsum with glauberite and halite units in the subsurface downstream of Cuarte. The halite shows a marked downvalley increase in thickness. Twelve terrace levels and seven pediment levels correlative to some of the terraces have been mapped in the studied area. Upstream of Cadrete, the terrace deposits, with a relatively constant thickness less than 4 m and overlying unsoluble bedrock, remain undeformed. Between Cadrete and Cuarte the deposits of some terraces show local thickening ( 60 m-thick terrace alluvium that fills a 5 km-long trough generated by synsedimentary subsidence phenomena caused primarily by the interstratal dissolution of halite. The older terraces (T1 to T4) show slight thickening (> 18 m) and locally truncate paleocollapse structures ascribed to the interstratal karstification of halite beds. The intermediate terraces (T5 to T7) correspond to degradation surfaces that grade downstream of Cuarte into aggradation flights underlain by the abruptly thickened deposits that fill this 5 km-long dissolution trough. Subsidence migrated episodically downstream during the generation of these terraces and the subsidence/aggradation rate was probably large enough to induce a base-level drop and knickpoint migration upstream generating strath terraces with convergent longitudinal profiles. The sedimentological changes that show the thickened terrace deposits in the subsidence area (high proportion of overbank fines (> 60%) including palustrine facies, gravel channels with lower width/depth ratio, multiple fining-upward cycles, decrease in the

  4. Single-walled carbon nanotube transparent conductive films fabricated by reductive dissolution and spray coating for organic photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Ostfeld, Aminy E.; Arias, Ana Claudia, E-mail: acarias@eecs.berkeley.edu [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720 (United States); Catheline, Amélie [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720 (United States); Linde Nanomaterials, Linde LLC, 1970 Diamond Street, San Marcos, California 92078 (United States); Ligsay, Kathleen; Kim, Kee-Chan; Fogden, Siân [Linde Nanomaterials, Linde LLC, 1970 Diamond Street, San Marcos, California 92078 (United States); Chen, Zhihua [Polyera Corporation, 8045 Lamon Avenue, Skokie, Illinois 60077 (United States); Facchetti, Antonio [Polyera Corporation, 8045 Lamon Avenue, Skokie, Illinois 60077 (United States); Center of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

    2014-12-22

    Solutions of unbundled and unbroken single-walled carbon nanotubes have been prepared using a reductive dissolution process. Transparent conductive films spray-coated from these solutions show a nearly twofold improvement in the ratio of electrical conductivity to optical absorptivity versus those deposited from conventional aqueous dispersions, due to substantial de-aggregation and sizable nanotube lengths. These transparent electrodes have been utilized to fabricate P3HT-PCBM organic solar cells achieving power conversion efficiencies up to 2.3%, comparable to those of solar cells using indium tin oxide transparent electrodes.

  5. The So-Called 'Face on Mars'

    Science.gov (United States)

    2002-01-01

    (Released 13 April 2002) The Science The so called 'Face on Mars' can be seen slightly above center and to the right in this THEMIS visible image. This 3-km long knob, located near 10o N, 40o W (320o E), was first imaged by the Viking spacecraft in the 1970's and was seen by some to resemble a face carved into the rocks of Mars. Since that time the Mars Orbiter Camera on the Mars Global Surveyor spacecraft has provided detailed views of this hill that clearly show that it is a normal geologic feature with slopes and ridges carved by eons of wind and downslope motion due to gravity. A similar-size hill in Phoenix, Arizona resembles a camel lying on the ground, and Phoenicians whimsically refer to it as Camelback Mountain. Like the hills and knobs of Mars, however, Camelback Mountain was carved into its unusual shape by thousands of years of erosion. The THEMIS image provides a broad perspective of the landscape in this region, showing numerous knobs and hills that have been eroded into a remarkable array of different shapes. Many of these knobs, including the 'Face', have several flat ledges partway up the hill slopes. These ledges are made of more resistant layers of rock and are the last remnants of layers that once were continuous across this entire region. Erosion has completely removed these layers in most places, leaving behind only the small isolated hills and knobs seen today. Many of the hills and ridges in this area also show unusual deposits of material that occur preferentially on the cold, north-facing slopes. It has been suggested that these deposits were 'pasted' on the slopes, with the distinct, rounded boundary on their upslope edges being the highest remaining point of this pasted-on layer. In several locations, such as in the large knob directly south of the 'Face', these deposits occur at several different heights on the hill. This observation suggests the layer once draped the entire knob and has since been removed from all but the north-facing

  6. The relationship between dissolution, gas oversaturation and outgassing of solutions determined by Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS).

    Science.gov (United States)

    Fitzpatrick, Dara; Evans-Hurson, Rachel; Krüse, Jacob; Vos, Bastiaan; McSweeney, Seán; Casaubieilh, Pierre; O'Gorman, Eadaoin

    2013-09-07

    The addition of a solute to a solvent is known to reduce the solubility of dissolved gases in solution which leads to gas oversaturation and outgassing of the solvent. The importance of the processes involved have received relatively little attention due to a limited capacity to elucidate their effects in real time. Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS) is a recently introduced acoustic approach which can monitor changes in the compressibility of a solvent due to outgassing. BARDS spectra show that a time dependent and quantitative reduction in gas oversaturation, following the dissolution of a simple salt, takes place over several hours. It is shown how vigorous agitation quickly equilibrates a solution, post dissolution, by removing gas oversaturation consistently. The level of oversaturation can be elucidated by further dissolving a marker compound into a solution consecutively. BARDS spectra indicate that the dissolution of a compound produces a consistent and quantifiable oversaturation of a solvent and a consistent and quantifiable outgassing. Low frequency sonication in an immersion bath is also shown to play no significant role in removing gas oversaturation post dissolution.

  7. A model for reaction-assisted polymer dissolution in LIGA.

    Energy Technology Data Exchange (ETDEWEB)

    Larson, Richard S.

    2004-05-01

    A new chemically-oriented mathematical model for the development step of the LIGA process is presented. The key assumption is that the developer can react with the polymeric resist material in order to increase the solubility of the latter, thereby partially overcoming the need to reduce the polymer size. The ease with which this reaction takes place is assumed to be determined by the number of side chain scissions that occur during the x-ray exposure phase of the process. The dynamics of the dissolution process are simulated by solving the reaction-diffusion equations for this three-component, two-phase system, the three species being the unreacted and reacted polymers and the solvent. The mass fluxes are described by the multicomponent diffusion (Stefan-Maxwell) equations, and the chemical potentials are assumed to be given by the Flory-Huggins theory. Sample calculations are used to determine the dependence of the dissolution rate on key system parameters such as the reaction rate constant, polymer size, solid-phase diffusivity, and Flory-Huggins interaction parameters. A simple photochemistry model is used to relate the reaction rate constant and the polymer size to the absorbed x-ray dose. The resulting formula for the dissolution rate as a function of dose and temperature is ?t to an extensive experimental data base in order to evaluate a set of unknown global parameters. The results suggest that reaction-assisted dissolution is very important at low doses and low temperatures, the solubility of the unreacted polymer being too small for it to be dissolved at an appreciable rate. However, at high doses or at higher temperatures, the solubility is such that the reaction is no longer needed, and dissolution can take place via the conventional route. These results provide an explanation for the observed dependences of both the dissolution rate and its activation energy on the absorbed dose.

  8. Principles of calcite dissolution in human and artificial otoconia.

    Directory of Open Access Journals (Sweden)

    Leif Erik Walther

    Full Text Available Human otoconia provide mechanical stimuli to deflect hair cells of the vestibular sensory epithelium for purposes of detecting linear acceleration and head tilts. During lifetime, the volume and number of otoconia are gradually reduced. In a process of degeneration morphological changes occur. Structural changes in human otoconia are assumed to cause vertigo and balance disorders such as benign paroxysmal positional vertigo (BPPV. The aim of this study was to investigate the main principles of morphological changes in human otoconia in dissolution experiments by exposure to hydrochloric acid, EDTA, demineralized water and completely purified water respectively. For comparison reasons artificial (biomimetic otoconia (calcite gelatin nanocomposits and natural calcite were used. Morphological changes were detected in time steps by the use of environmental scanning electron microscopy (ESEM. Under in vitro conditions three main dissolution mechanisms were identified as causing characteristic morphological changes of the specimen under consideration: pH drops in the acidic range, complex formation with calcium ions and changes of ion concentrations in the vicinity of otoconia. Shifts in pH cause a more uniform reduction of otoconia size (isotropic dissolution whereas complexation reactions and changes of the ionic concentrations within the surrounding medium bring about preferred attacks at specific areas (anisotropic dissolution of human and artificial otoconia. Owing to successive reduction of material, all the dissolution mechanisms finally produce fragments and remnants of otoconia. It can be assumed that the organic component of otoconia is not significantly attacked under the given conditions. Artificial otoconia serve as a suitable model system mimicking chemical attacks on biogenic specimens. The underlying principles of calcite dissolution under in vitro conditions may play a role in otoconia degeneration processes such as BPPV.

  9. Automated Face Recognition System

    Science.gov (United States)

    1992-12-01

    atestfOl.feature-vectjJ -averageljJ); for(j=l; <num-coefsj++) for(i= 5 num-train-faces;i++) sdlQjI -(btrainhil.feaure..vecU1- veagU (btraintil.feature- vecU ... vecU ])* (atest(O1.feature-vecUJ - btrain[iI.feature- vecU ]) + temp; btrain(ii.distance = sqrt ( (double) temp); I**** Store the k-nearest neighbors rank

  10. Auto Industry Faces Change

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A number of indicators show that China's auto industry is facing a new round of large-scale restructuring. When the global auto industry was undergoing reorganization 10 years ago, China's auto industry was in its early stages, acting in a relatively closed market, and thus it missed out on that important event. However, the situation is different today. In the past decade, China's auto industry has grown at a rapid pace. While the world's major transnational companies are

  11. Dissolution of spent nuclear fuel in carbonate-peroxide solution

    Science.gov (United States)

    Soderquist, Chuck; Hanson, Brady

    2010-01-01

    This study shows that spent UO2 fuel can be completely dissolved in a room temperature carbonate-peroxide solution apparently without attacking the metallic Mo-Tc-Ru-Rh-Pd fission product phase. In parallel tests, identical samples of spent nuclear fuel were dissolved in nitric acid and in an ammonium carbonate, hydrogen peroxide solution. The resulting solutions were analyzed for strontium-90, technetium-99, cesium-137, europium-154, plutonium, and americium-241. The results were identical for all analytes except technetium, where the carbonate-peroxide dissolution had only about 25% of the technetium that the nitric acid dissolution had.

  12. Influence of splitting on dissolution properties of metoprolol tablets.

    Science.gov (United States)

    Vranić, Edina; Uzunović, Alija

    2009-08-01

    The objective of this work was to compare several profiles of dissolution data for metoprolol controlled release tablet formulations in order to identify possible changes in dissolution profiles of whole and scored tablets. Adequate design of score lines (on one or both sides) as well as the technology of preparation of tablet mixtures ensure forming a score line of adequate thickness, shape, size, curvature. According to the obtained results, this type of extended release formulation is eligible for splitting and use in therapy either as a whole or scored tablets.

  13. Reactive-infiltration instabilities in rocks. Fracture dissolution

    CERN Document Server

    Szymczak, Piotr

    2012-01-01

    A reactive fluid dissolving the surface of a uniform fracture will trigger an instability in the dissolution front, leading to spontaneous formation of pronounced well-spaced channels in the surrounding rock matrix. Although the underlying mechanism is similar to the wormhole instability in porous rocks there are significant differences in the physics, due to the absence of a steadily propagating reaction front. In previous work we have described the geophysical implications of this instability in regard to the formation of long conduits in soluble rocks. Here we describe a more general linear stability analysis, including axial diffusion, transport limited dissolution, non-linear kinetics, and a finite length system.

  14. Do Workplace Sex Ratios Affect Partnership Formation and Dissolution?

    DEFF Research Database (Denmark)

    Svarer, Michael

    are not important for the overall transition rate from singlehood to partnership. The results suggest that the workplace constitutes a more important marriage market segment for individuals who are already in a partnership presumably due to higher search cost for (alternative) partners in general.......In this paper, I analyse the association between workplace sex ratios and partnership formation and dissolution. I find that the risk of dissolution increases with the fraction of coworkers of the opposite sex at both the female and male workplace. On the other hand, workplace sex ratios...

  15. Effects of alteration product precipitation on glass dissolution

    Energy Technology Data Exchange (ETDEWEB)

    Strachan, Denis M.; Neeway, James J.

    2014-06-01

    Understanding the mechanisms that control the durability of nuclear waste glass is paramount if reliable models are to be constructed so that the glass dissolution rate in a given geological repository can be calculated. Presently, it is agreed that (boro)silicate glasses dissolve in water at a rate dependent on the solution concentration of orthosilicic acid (H4SiO4) with higher [H4SiO4] leading to lower dissolution rates. Once the reaction has slowed as a result of the buildup of H4SiO4, another increase in the rate has been observed that corresponds to the precipitation of certain silica-bearing alteration products. However, it has also been observed that the concentration of silica-bearing solution species does not significantly decrease, indicating saturation, while other glass tracer elements concentrations continue to increase, indicating that the glass is still dissolving. In this study, we have used the Geochemist’s Workbench code to investigate the relationship between glass dissolution rates and the precipitation rate of a representative zeolitic silica-bearing alteration product, analcime [Na(AlSi2O6)∙H2O]. To simplify the calculations, we suppressed all alteration products except analcime, gibbsite (Al(OH)3), and amorphous silica. The pseudo-equilibrium-constant matrix for amorphous silica was substituted for the glass pseudo-equilibrium-constant matrix because it has been shown that silicate glasses act as a silica-only solid with respect to kinetic considerations. In this article, we present the results of our calculations of the glass dissolution rate at different values for the analcime precipitation rate constant and the effects of varying the glass dissolution rate constant at a constant analcime precipitation rate constant. From the simulations we conclude, firstly, that the rate of glass dissolution is dependent on the kinetics of

  16. Studies of thermal dissolution of RDX in TNT melt

    Science.gov (United States)

    Suvorova, N. A.; Hamilton, V. T.; Oschwald, D. M.; Balakirev, F. F.; Smilowitz, L. B.; Henson, B. F.

    2017-01-01

    The thermal response of energetic materials is studied due to its importance in issues of material safety and surety. Secondary high explosives which melt before they thermally decompose present challenging systems to model due to the addition of material flow. Composition B is a particularly challenging system due to its multiphase nature with a low melt component (TNT) and a high melt component (RDX). The dissolution of RDX crystals in molten TNT at the temperature below RDX melting point has been investigated using hot stage microscopy. In this paper, we present data on the dissolution rate of RDX crystals in molten TNT as a function of temperature above the TNT melt.

  17. [Dissolution therapy of struvite calculi with solution G].

    Science.gov (United States)

    Hosomi, M; Maeda, O; Matsumiya, K; Koide, T; Takaha, M; Oka, T; Sonoda, T

    1988-07-01

    In 6 patients (9 kidneys) irrigation with Solution G in the renal pelvis was performed for the dissolution of their infectious stones. Staghorn calculi larger than 30 mm in diameter were observed in all patients. In two kidneys all stones were dissolved and the rest were dissolved into small fragments that constituted no problem in those kidneys. Irrigation was done with no major side effects or complications. The dissolution of infectious stones with Solution G is another possible treatment that could be first chosen among percutaneous nephrolithotripsy, extracorporeal shock wave lithotripsy and other treatments.

  18. Spent fuel dissolution studies FY 1991 to 1994

    Energy Technology Data Exchange (ETDEWEB)

    Gray, W.J.; Wilson, C.N.

    1995-12-01

    Dissolution and transport as a result of groundwater flow are generally accepted as the primary mechanisms by which radionuclides from spent fuel placed in a geologic repository could be released to the biosphere. To help provide a source term for performance assessment calculations, dissolution studies on spent fuel and unirradiated uranium oxides have been conducted over the past few years at Pacific Northwest National Laboratory (PNNL) in support of the Yucca Mountain Site Characterization Project. This report describes work for fiscal years 1991 through 1994. The objectives of these studies and the associated conclusions, which were based on the limited number of tests conducted so far, are described in the following subsections.

  19. Do Workplace Sex Ratios Affect Partnership Formation and Dissolution?

    DEFF Research Database (Denmark)

    Svarer, Michael

    are not important for the overall transition rate from singlehood to partnership. The results suggest that the workplace constitutes a more important marriage market segment for individuals who are already in a partnership presumably due to higher search cost for (alternative) partners in general.......In this paper, I analyse the association between workplace sex ratios and partnership formation and dissolution. I find that the risk of dissolution increases with the fraction of coworkers of the opposite sex at both the female and male workplace. On the other hand, workplace sex ratios...

  20. An AFM study of calcite dissolution in concentrated electrolyte solutions

    Science.gov (United States)

    Ruiz Agudo, E.; Putnis, C. V.; Putnis, A.; Rodriguez-Navarro, C.

    2009-04-01

    Calcite-solution interactions are of a paramount importance in a range of processes such as the removal of heavy metals, carbon dioxide sequestration, landscape modeling, weathering of building stone and biomineralization. Water in contact with minerals often carries significant amounts of solutes; additionally, their concentration may vary due to evaporation and condensation. It is well known that calcite dissolution is affected dramatically by the presence of such solutes. Here we present investigations on the dissolution of calcite in the presence of different electrolytes. Both bulk (batch reactors) experiments and nanoscale (in situ AFM) techniques are used to study the dissolution of calcite in a range of solutions containing alkaly cations balanced by halide anions. Previous works have indicated that the ionic strength has little influence in calcite dissolution rates measured from bulk experiments (Pokrovsky et al. 2005; Glendhill and Morse, 2004). Contrary to these results, our quantitative analyses of AFM observations show an enhancement of the calcite dissolution rate with increasing electrolyte concentration. Such an effect is concentration-dependent and it is most evident in concentrated solutions. AFM experiments have been carried out in a fluid cell using calcite cleavage surfaces in contact with solutions of simple salts of the alkaly metals and halides at different undersaturations with respect to calcite to try to specify the effect of the ionic strength on etch pit spreading rate and calcite dissolution rate. These results show that the presence of soluble salts may critically affect the weathering of carbonate rocks in nature as well as the decay of carbonate stone in built cultural heritage. References: Pokrosky, O.S.; Golubev, S.V.; Schott, J. Dissolution kinetics of calcite, dolomite and magnesite at 25°C and 0 to 50 atm pCO2. Chemical Geology, 2005, 217 (3-4) 239-255. Glendhill, D.K.; Morse, J.W. Dissolution kinetics of calcite in Na

  1. Biodegradation and dissolution of polyaromatic hydrocarbons by Stenotrophomonas sp.

    Science.gov (United States)

    Tiwari, Bhagyashree; Manickam, N; Kumari, Smita; Tiwari, Akhilesh

    2016-09-01

    The aim of this work was to study the biodegradation capabilities of a locally isolated bacterium, Stenotrophomonas sp. strain IITR87 to degrade the polycyclic aromatic hydrocarbons and also check the preferential biodegradation of polycyclic aromatic hydrocarbons (PAHs). From preferential substrate degradation studies, it was found that Stenotrophomonas sp. strain IITR87 first utilized phenanthrene (three membered ring), followed by pyrene (four membered ring), then benzo[α]pyrene (five membered ring). Dissolution study of PAHs with surfactants, rhamnolipid and tritonX-100 showed that the dissolution of PAHs increased in the presence of surfactants.

  2. Observance of polymorphic behaviour during dissolution of insulin and lysozyme

    Directory of Open Access Journals (Sweden)

    A. Bernardo

    2005-09-01

    Full Text Available Although protein crystallization is a unit operation with potentially high separation factors, it has not been widely used in industry. Protein crystallization studies and practices have hitherto been largely limited to crystallography protocols. Knowledge of the behaviour of protein in solution would help to overcome empiric limitations in protein crystallisation. Thus, dissolution of porcine insulin and hen egg white lysozyme was studied and an unusual variation in solute concentration, with a concentration peak for short dissolution times, was verified. Polymorphic behaviour of protein in solution was observed, which altered physical properties such as solubility.

  3. GLASS COMPOSITION AND SOLUTION SPECIATION EFFECTS ON STAGE III DISSOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Pantano, Carlo G; Trivelpiece, Cory L; Rice, Jarret A

    2017-10-03

    To understand and mitigate the onset of Stage III corrosion of multicomponent oxides waste glasses. Stage III refers to a resumption of the high initial rate of glass dissolution in some glass samples that have otherwise exhibited dissolution at the much lower residual rate for a long time (Stage II). Although the onset of Stage III is known to occur concurrently with the precipitation of particular alteration products, the root cause of the transition is still unknown. Certain glass compositions (notably AFCI) and high pH environmental conditions are also associated with this observed transition.

  4. Controlled dissolution of colossal quantities of nitrogen in stainless steel

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Somers, Marcel A. J.

    2006-01-01

    The solubility of nitrogen in austenitic stainless steel was investigated thermogravimetrically by equilibrating thin foils of AISI 304 and AISI 316 in ammonia/hydrogen gas mixtures. Controlled dissolution of colossal amounts of nitrogen under metastable equilibrium conditions was realized......, with nitrogen contents as high as corresponding to an occupancy of yN = 0.61 of the interstitial sublattice, i.e. about 38 at.% N. Associated with the dissolution of these unprecedented nitrogen contents in an austenitic matrix a reversible volume expansion of the austenite lattice occurred for yN > 0...

  5. Improvement of dissolution rate of indomethacin by inkjet printing

    DEFF Research Database (Denmark)

    Wickström, Henrika; Palo, Mirja; Rijckaert, Karen

    2015-01-01

    The aim of this study was to prepare printable inks of the poorly water soluble drug indomethacin (IMC), fabricate printed systems with flexible doses and investigate the effect of ink excipients on the printability, dissolution rate and the solid state properties of the drug. A piezoelectric....... Increased dissolution rate was obtained for all formulations. The formulation with IMC and ARG printed on transparency film resulted in a co-amorphous system. The solid state characteristics of the printed drug on porous paper substrates were not possible to determine due to strong interference from...

  6. Dissolution Dynamic Nuclear Polarization capability study with fluid path

    DEFF Research Database (Denmark)

    Malinowski, Ronja Maja; Lipsø, Hans Kasper Wigh; Lerche, Mathilde Hauge

    2016-01-01

    Signal enhancement by hyperpolarization is a way of overcoming the low sensitivity in magnetic resonance; MRI in particular. One of the most well-known methods, dissolution Dynamic Nuclear Polarization, has been used clinically in cancer patients. One way of ensuring a low bioburden of the hyperp......Signal enhancement by hyperpolarization is a way of overcoming the low sensitivity in magnetic resonance; MRI in particular. One of the most well-known methods, dissolution Dynamic Nuclear Polarization, has been used clinically in cancer patients. One way of ensuring a low bioburden...

  7. Decoding of faces and face components in face-sensitive human visual cortex

    Directory of Open Access Journals (Sweden)

    David F Nichols

    2010-07-01

    Full Text Available A great challenge to the field of visual neuroscience is to understand how faces are encoded and represented within the human brain. Here we show evidence from functional magnetic resonance imaging (fMRI for spatially distributed processing of the whole face and its components in face-sensitive human visual cortex. We used multi-class linear pattern classifiers constructed with a leave-one-scan-out verification procedure to discriminate brain activation patterns elicited by whole faces, the internal features alone, and the external head outline alone. Furthermore, our results suggest that whole faces are represented disproportionately in the fusiform cortex (FFA whereas the building blocks of faces are represented disproportionately in occipitotemporal cortex (OFA. Faces and face components may therefore be organized with functional clustering within both the FFA and OFA, but with specialization for face components in the OFA and the whole face in the FFA.

  8. Suppression of Aluminum Current Collector Dissolution by Protective Ceramic Coatings for Better High-Voltage Battery Performance.

    Science.gov (United States)

    Heckmann, Andreas; Krott, Manuel; Streipert, Benjamin; Uhlenbruck, Sven; Winter, Martin; Placke, Tobias

    2017-01-04

    Batteries based on cathode materials that operate at high cathode potentials, such as LiNi0.5 Mn1.5 O4 (LNMO), in lithium-ion batteries or graphitic carbons in dual-ion batteries suffer from anodic dissolution of the aluminum (Al) current collector in organic solvent-based electrolytes based on imide salts, such as lithium bis(trifluoromethanesulfonyl) imide (LiTFSI). In this work, we developed a protective surface modification for the Al current collector by applying ceramic coatings of chromium nitride (Crx N) and studied the anodic Al dissolution behavior. By magnetron sputter deposition, two different coating types, which differ in their composition according to the CrN and Cr2 N phases, were prepared and characterized by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and their electronic conductivity. Furthermore, the anodic dissolution behavior was studied by cyclic voltammetry and chronocoulometry measurements in two different electrolyte mixtures, that is, LiTFSI in ethyl methyl sulfone and LiTFSI in ethylene carbonate/dimethyl carbonate 1:1 (by weight). These measurements showed a remarkably reduced current density or cumulative charge during the charge process, indicating an improved anodic stability of the protected Al current collector. The coating surfaces after electrochemical treatment were characterized by means of SEM and XPS, and the presence or lack of pit formation, as well as electrolyte degradation products could be well correlated to the electrochemical results.

  9. Face-space: A unifying concept in face recognition research.

    Science.gov (United States)

    Valentine, Tim; Lewis, Michael B; Hills, Peter J

    2016-10-01

    The concept of a multidimensional psychological space, in which faces can be represented according to their perceived properties, is fundamental to the modern theorist in face processing. Yet the idea was not clearly expressed until 1991. The background that led to the development of face-space is explained, and its continuing influence on theories of face processing is discussed. Research that has explored the properties of the face-space and sought to understand caricature, including facial adaptation paradigms, is reviewed. Face-space as a theoretical framework for understanding the effect of ethnicity and the development of face recognition is evaluated. Finally, two applications of face-space in the forensic setting are discussed. From initially being presented as a model to explain distinctiveness, inversion, and the effect of ethnicity, face-space has become a central pillar in many aspects of face processing. It is currently being developed to help us understand adaptation effects with faces. While being in principle a simple concept, face-space has shaped, and continues to shape, our understanding of face perception.

  10. Dissolution Flowsheet for High Flux Isotope Reactor Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, W. E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Rudisill, T. S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); O' Rourke, P. E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Karay, N. S [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-09-27

    As part of the Spent Nuclear Fuel (SNF) processing campaign, H-Canyon is planning to begin dissolving High Flux Isotope Reactor (HFIR) fuel in late FY17 or early FY18. Each HFIR fuel core contains inner and outer fuel elements which were fabricated from uranium oxide (U3O8) dispersed in a continuous Al phase using traditional powder metallurgy techniques. Fuels fabricated in this manner, like other SNF’s processed in H-Canyon, dissolve by the same general mechanisms with similar gas generation rates and the production of H2. The HFIR fuel cores will be dissolved and the recovered U will be down-blended into low-enriched U. HFIR fuel was previously processed in H-Canyon using a unique insert in both the 6.1D and 6.4D dissolvers. Multiple cores will be charged to the same dissolver solution maximizing the concentration of dissolved Al. The objective of this study was to identify flowsheet conditions through literature review and laboratory experimentation to safely and efficiently dissolve the HFIR fuel in H-Canyon. Laboratory-scale experiments were performed to evaluate the dissolution of HFIR fuel using both Al 1100 and Al 6061 T6 alloy coupons. The Al 1100 alloy was considered a representative surrogate which provided an upper bound on the generation of flammable (i.e., H2) gas during the dissolution process. The dissolution of the Al 6061 T6 alloy proceeded at a slower rate than the Al 1100 alloy and was used to verify that the target Al concentration in solution could be achieved for the selected Hg concentration. Mass spectrometry and Raman spectroscopy were used to provide continuous monitoring of the concentration of H2 and other permanent gases in the dissolution offgas allowing the development of H2 generation rate profiles. The H2 generation rates were subsequently used to evaluate if a full HFIR core could be dissolved in an H-Canyon dissolver without exceeding 60% of the calculated lower

  11. Dissolution Flowsheet for High Flux Isotope Reactor Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, W. E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Rudisill, T. S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); O' Rourke, P. E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Karay, N. S [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-09-27

    As part of the Spent Nuclear Fuel (SNF) processing campaign, H-Canyon is planning to begin dissolving High Flux Isotope Reactor (HFIR) fuel in late FY17 or early FY18. Each HFIR fuel core contains inner and outer fuel elements which were fabricated from uranium oxide (U3O8) dispersed in a continuous Al phase using traditional powder metallurgy techniques. Fuels fabricated in this manner, like other SNF’s processed in H-Canyon, dissolve by the same general mechanisms with similar gas generation rates and the production of H2. The HFIR fuel cores will be dissolved and the recovered U will be down-blended into low-enriched U. HFIR fuel was previously processed in H-Canyon using a unique insert in both the 6.1D and 6.4D dissolvers. Multiple cores will be charged to the same dissolver solution maximizing the concentration of dissolved Al. The objective of this study was to identify flowsheet conditions through literature review and laboratory experimentation to safely and efficiently dissolve the HFIR fuel in H-Canyon. Laboratory-scale experiments were performed to evaluate the dissolution of HFIR fuel using both Al 1100 and Al 6061 T6 alloy coupons. The Al 1100 alloy was considered a representative surrogate which provided an upper bound on the generation of flammable (i.e., H2) gas during the dissolution process. The dissolution of the Al 6061 T6 alloy proceeded at a slower rate than the Al 1100 alloy, and was used to verify that the target Al concentration in solution could be achieved for the selected Hg concentration. Mass spectrometry and Raman spectroscopy were used to provide continuous monitoring of the concentration of H2 and other permanent gases in the dissolution offgas, allowing the development of H2 generation rate profiles. The H2 generation rates were subsequently used to evaluate if a full HFIR core could be dissolved in an H-Canyon dissolver without exceeding 60% of the

  12. Age-dependent face detection and face categorization performance.

    Science.gov (United States)

    Carbon, Claus-Christian; Grüter, Martina; Grüter, Thomas

    2013-01-01

    Empirical studies on the development of face processing skills with age show inconsistent patterns concerning qualitative vs. quantitative changes over time or the age range for peak cognitive performance. In the present study, we tested the proficiency in face detection and face categorization with a large sample of participants (N = 312; age range: 2-88 yrs). As test objects, we used so-called Mooney faces, two-tone (black and white) images of faces lacking critical information of a local, featural and relational nature, reflecting difficult real world face processing conditions. We found that performance in the assessment of gender and age from Mooney faces increases up to about age 15, and decreases from 65 years on. The implications of these findings are discussed in the light of classic and recent findings from face development literature.

  13. Non-destructive Prediction of Enteric Coating Layer Thickness and Drug Dissolution Rate by Near-infrared spectroscopy and X-ray computed tomography.

    Science.gov (United States)

    Ariyasu, Aoi; Hattori, Yusuke; Otsuka, Makoto

    2017-04-07

    The coating layer thickness of enteric-coated tablets is a key factor that determines the drug dissolution rate from the tablet. Near-infrared spectroscopy (NIRS) enables non-destructive and quick measurement of the coating layer thickness, and thus allows the investigation of the relation between enteric coating layer thickness and drug dissolution rate. Two marketed products of aspirin enteric-coated tablets were used in this study, and the correlation between the predicted coating layer thickness and the obtained drug dissolution rate was investigated. Our results showed correlation for one product; the drug dissolution rate decreased with the increase in enteric coating layer thickness, whereas, there was no correlation for the other product. Additional examination of the distribution of coating layer thickness by X-ray computed tomography (CT) showed homogenous distribution of coating layer thickness for the former product, whereas the latter product exhibited heterogeneous distribution within the tablet, as well as inconsistent trend in the distribution between the tablets. It was suggested that this heterogeneity and inconsistent trend in layer thickness distribution contributed to the absence of correlation between the layer thickness of the face and side regions of the tablets, which resulted in the loss of correlation between the coating layer thickness and drug dissolution rate. Therefore, the predictability of drug dissolution rate from enteric-coated tablets depended on the homogeneity of the coating layer thickness. In addition, the importance of micro analysis, X-ray CT in this study, was suggested even if the macro analysis, NIR spectroscopy (NIRS) in this study, are finally applied for the measurement.

  14. Dissolution models for glassy waste forms; Modeles de dissolution des formes de dechets a base de verre

    Energy Technology Data Exchange (ETDEWEB)

    Harvey, K.B.

    1995-06-01

    As a part of the Canadian Nuclear Fuel Waste Management Program (CNFWMP), a suite of models has been developed that describe the dissolution of a glass under a variety of conditions. This work had two aims: to develop and present the models in such a way that the equations associated with models could be used to unambiguously extract the fundamental dissolution constants of a glass from experimental data, and to demonstrate the correspondence between models and experiments over a sufficiently broad range of conditions such that the models could be used with confidence to forecast performance under conditions that might not be realistically accessible to experiments.

  15. A comparative study of face processing using scrambled faces

    OpenAIRE

    Taubert, Jessica; Aagten-Murphy, David; Parr, Lisa A.

    2012-01-01

    It is a widespread assumption that all primate species process faces in the same way because the species are closely related and they engage in similar social interactions. However, this approach ignores potentially interesting and informative differences that may exist between species. This paper describes a comparative study of holistic face processing. Twelve subjects (six chimpanzees Pan troglodytes and six rhesus monkeys Macaca mulatta) were trained to discriminate whole faces (faces wit...

  16. Face-to-Face Interference in Typical and Atypical Development

    Science.gov (United States)

    Riby, Deborah M.; Doherty-Sneddon, Gwyneth; Whittle, Lisa

    2012-01-01

    Visual communication cues facilitate interpersonal communication. It is important that we look at faces to retrieve and subsequently process such cues. It is also important that we sometimes look away from faces as they increase cognitive load that may interfere with online processing. Indeed, when typically developing individuals hold face gaze…

  17. Pulsed laser deposition of pepsin thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kecskemeti, G. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary)]. E-mail: kega@physx.u-szeged.hu; Kresz, N. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary); Smausz, T. [Hungarian Academy of Sciences and University of Szeged, Research Group on Laser Physics, H-6720 Szeged, Dom ter 9 (Hungary); Hopp, B. [Hungarian Academy of Sciences and University of Szeged, Research Group on Laser Physics, H-6720 Szeged, Dom ter 9 (Hungary); Nogradi, A. [Department of Ophthalmology, University of Szeged, H-6720, Szeged, Koranyi fasor 10-11 (Hungary)

    2005-07-15

    Pulsed laser deposition (PLD) of organic and biological thin films has been extensively studied due to its importance in medical applications among others. Our investigations and results on PLD of a digestion catalyzing enzyme, pepsin, are presented. Targets pressed from pepsin powder were ablated with pulses of an ArF excimer laser ({lambda} = 193 nm, FWHM = 30 ns), the applied fluence was varied between 0.24 and 5.1 J/cm{sup 2}. The pressure in the PLD chamber was 2.7 x 10{sup -3} Pa. The thin layers were deposited onto glass and KBr substrates. Our IR spectroscopic measurements proved that the chemical composition of deposited thin films is similar to that of the target material deposited at 0.5 and 1.3 J/cm{sup 2}. The protein digesting capacity of the transferred pepsin was tested by adapting a modified 'protein cube' method. Dissolution of the ovalbumin sections proved that the deposited layers consisted of catalytically active pepsin.

  18. Premarital Cohabitation and Marital Dissolution: An Examination of Recent Marriages

    Science.gov (United States)

    Manning, Wendy D.; Cohen, Jessica A.

    2012-01-01

    An ongoing question remains for family researchers: Why does a positive association between cohabitation and marital dissolution exist when one of the primary reasons to cohabit is to test relationship compatibility? Drawing on recently collected data from the 2006-2008 National Survey of Family Growth, the authors examined whether premarital…

  19. Compaction of porous rock by dissolution on discrete stylolites

    DEFF Research Database (Denmark)

    Angheluta, Luiza; Mathiesen, Joachim; Aharonov, Einat

    2012-01-01

    Compaction of sedimentary porous rock by dissolution and precipitation is a complex deformation mechanism, that is often localized on stylolites and pressure solution seams. We consider a one-dimensional model of compaction near a thin clay-rich stylolite embedded in a porous rock. Under...

  20. The First Dissolution of Real Spent Fuel in CRARL

    Institute of Scientific and Technical Information of China (English)

    LIU; Fang; CHANG; Shang-wen; LUO; Fang-xiang; YAN; Tai-hong; HE; Hui; ZHENG; Wei-fang

    2015-01-01

    The dissolution of the spent fuel was accomplished in CRARL under the cooperation among three divisions of department of radiochemistry.The experiment was started in 22September,and was completed in 27September.Two batches spent fuel of xx reactor was dissolved in these 6days.About 13liters feed of the co-decontamination

  1. Impact of fillers on dissolution kinetic of fenofibrate dry foams.

    Science.gov (United States)

    Lenz, Elisabeth; Sprunk, Angela; Kleinebudde, Peter; Page, Susanne

    2015-01-01

    Dry foam technology reveals the opportunity to improve the dissolution behavior of poorly soluble drugs tending to agglomeration due to micronization. In this study, the impact of fillers on the manufacturability, the properties of dry foams and granules as well as the dissolution kinetics of dry foam tablets was investigated using fenofibrate as a model compound. Different maltodextrins and dried glucose syrups, a maltodextrin-phosphatidylcholine complex, isomalt and a 1:1 mixture of mannitol/glucose syrup were used as filler. Within the group of maltodextrins and glucose syrups, the influences of dextrose equivalent (DE), particle morphology and botanical source of starch were investigated. Comparable macroscopic foam structures were obtained with maltodextrins and glucose syrups whereas different foam morphologies were obtained for the other fillers tested. Regarding the maltodextrins and glucose syrups, different physicochemical and particle properties had a minor impact on granule characteristics and tablet dissolution. Using the maltodextrin-phosphatidylcholine complex resulted in a low specific surface area of the granules and a slow tablet dissolution caused by a slow disintegration. In contrast, a high specific surface area and a fast release were obtained with isomalt and glucose syrup/mannitol mixture indicating that high soluble low molecular weight fillers enable the development of fast dissolving dry foam tablets.

  2. KINETICS OF DISSOLUTION OF PHOSPHORITE IN ACID MIXTURES

    African Journals Online (AJOL)

    The effect of hydrochloric acid on the dissolution of fluorapatite by sulphuric acid was studied at various H2SO_,_:HCl volume ratios ranging from 100 to 0 volume % of the ... Indeed only diffusion controlled processes are affected by the stirring speed [27]. ... surface area of the dissolving mineral [30], in this case fluorapatite.

  3. A Flow Injection Dissolution Testing System and Its Application

    Institute of Scientific and Technical Information of China (English)

    Jiagen Lv; Xiaowei Sheng; Dadong Zhan; Yue Hu; Zhiqi Zhang

    2003-01-01

    @@ The determination of the release rate of drugs is essential for the development of testing new dosage forms and for quality control in pharmaceutical industries. Dissolution testing of pharmaceutical dosage forms is a laborious process that generates large number of samples.

  4. Enhancement of solubility and dissolution rate of atorvastatin ...

    African Journals Online (AJOL)

    Method: Co-crystallization of AC in equimolar ratio with isonicotinamide (INA) was carried out by slow ... The enhancement of aqueous solubility and dissolution rate of AC with co-crystallization may be a ..... Hsu PC, Lin HL, Wang SL, Lin SY.

  5. Evolution of dissolution patterns by mixing corrosion in karst systems

    Science.gov (United States)

    Cabeza, Yoar; Hidalgo, Juan J.; Dentz, Marco; Carrera, Jesús

    2014-05-01

    Conduit enlargement in a karst system is usually assumed to be controlled by non-linear kinetics that allow aggressive water to penetrate along fractures (Gabrovšek and Dreybrodt, 2000, Water. Resour. Res.). However, other mechanism known as mixing corrosion may be decisive for the geometry of the resulting dissolution patterns, at least at depth. Mixing corrosion is caused by the renovation of the dissolution capacity that happens when two waters saturated with respect to calcite but with different CO2 partial pressure mix. In this case, the reaction rate is mixing-controlled and can be quantified in terms of the mixing proportion of the conservative components of the chemical system (De Simoni et al. 2005, Water. Resour. Res.). Therefore, the porosity creation governed by the reaction rate will depend on the chemical differences between the end members and by the degree of mixing. The aim of this work is to study the evolution of the porosity and permeability within a carbonate matrix by mixing-driven dissolution under different diffusion regimes. The speciation of the chemical system is calculated using CHEPROO. Flow and transport are modeled using an ad hoc code that accounts for feedback between reactions, porosity creation and permeability changes. The effects of the initial porosity field, water chemistry and the resulting geometry of the dissolution patterns are explored for different scenarios.

  6. A Dynamic Flux Dissolution Model for Oxygen Steelmaking

    Science.gov (United States)

    Kadrolkar, Ameya; Andersson, Nils Å. I.; Dogan, Neslihan

    2017-02-01

    A modified model for prediction of flux dissolution in oxygen steelmaking process is presented in this study. The aim of this paper is to introduce a procedure for simulating the amount of dissolved lime with respect to the saturation concentration of CaO by coupling the existing thermodynamic and kinetic models simultaneously. The procedure is developed to calculate the saturation concentrations/solubility of CaO in slag using thermodynamic models namely FactSage™, Cell Model, and Thermo-Calc™. Total amount of dissolved lime is evaluated by integrating solubility values in the rate equation of lime dissolution over time taking into account the effects of physical properties and temperature of slag and particle size of flux additions and validated against industrial data available in literature. Comparison between measured and calculated undissolved lime shows a good agreement between them using any thermodynamic models even though there are some differences in the predictions of saturation concentration of CaO in slag. It has been shown that two distinct control mechanisms for lime dissolution in BOF slags exist and consideration of the free lime-controlled mechanism is essential for accurate prediction of dissolution rate of lime in slag.

  7. Adolescent Sexuality and the Risk of Marital Dissolution

    Science.gov (United States)

    Paik, Anthony

    2011-01-01

    This research investigates whether first sexual intercourse during adolescence is associated with increased risk of first marriage dissolution and tests whether the results are consistent with causal or selection explanations. Drawing on a sample of 3,793 ever-married women from the 2002 National Survey of Family Growth, this study estimated…

  8. Ocean acidification: Towards a better understanding of calcite dissolution

    Science.gov (United States)

    Wilhelmus, Monica M.; Adkins, Jess; Menemenlis, Dimitris

    2016-11-01

    The drastic increase of anthropogenic CO2 emissions over the past two centuries has altered the chemical structure of the ocean, acidifying upper ocean waters. The net impact of this pH decrease on marine ecosystems is still unclear, given the unprecedented rate at which CO2 is being released into the atmosphere. As part of the carbon cycle, calcium carbonate dissolution in sediments neutralizes CO2: phytoplankton at the surface produce carbonate minerals, which sink and reach the seafloor after the organisms die. On time scales of thousands of years, the calcium carbonate in these shells ultimately reacts with CO2 in seawater. Research in this field has been extensive; nevertheless, the dissolution rate law, the impact of boundary layer transport, and the feedback with the global ocean carbon cycle remain controversial. Here, we (i) develop a comprehensive numerical framework via 1D modeling of carbonate dissolution in sediments, (ii) approximate its impact on water column properties by implementing a polynomial approximation to the system's response into a global ocean biogeochemistry general circulation model (OBGCM), and (iii) examine the OBGCM sensitivity response to different formulations of sediment boundary layer properties. We find that, even though the burial equilibration time scales of calcium carbonate are in the order of thousands of years, the formulation of a bottom sediment model along with an improved description of the dissolution rate law can have consequences on multi-year to decadal time scales.

  9. Enhanced dissolution of sildenafil citrate as dry foam tablets.

    Science.gov (United States)

    Sawatdee, Somchai; Atipairin, Apichart; Sae Yoon, Attawadee; Srichana, Teerapol; Changsan, Narumon

    2017-01-30

    Dry foam formulation technology is alternative approach to enhance dissolution of the drug. Sildenafil citrate was suspended in sodium dodecyl sulfate solution and adding a mixture of maltodextrin and mannitol as diluent to form a paste. Sildenafil citrate paste was passed through a nozzle spray bottle to obtain smooth foam. The homogeneous foam was dried in a vacuum oven and sieved to obtain dry foam granules. The granules were mixed with croscarmellose sodium, magnesium stearate and compressed into tablet. All formulations were evaluated for their physicochemical properties and dissolution profiles. All the tested excipients were compatible with sildenafil citrate by both differential scanning calorimetry (DSC) and infrared (IR) analysis. There are no X-ray diffraction (XRD) peaks representing crystals of sildenafil citrate observed form dry foam formulations. The hardness of tablets was about 5 kg, friability test foam tablet had higher dissolution rate in 0.1 N HCl in comparison with commercial sildenafil citrate tablet, sildenafil citrate prepared by direct compression and wet granulation method. Sildenafil citrate dry foam tablet with the high-level composition of surfactant, water and diluent showed enhanced dissolution rate than that of the lower-level composition of these excipients. This formulation was stable under accelerated conditions for at least 6 months.

  10. Dissolution of Uranium Oxides Under Alkaline Oxidizing Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Smith, S.C.; Peper, S.M.; Douglas, M.; Ziegelgruber, K.L. [PNNL, PO Box 999, MS P8-08, Richland, WA 99352 (United States)

    2009-06-15

    Understanding the dissolution of uranium oxides is critical for designing and optimizing next-generation spent nuclear fuel (SNF) reprocessing methods. Bench scale experiments were conducted to determine the optimal dissolution parameters for size-fractionated aliquots of UO{sub 2}, UO{sub 3}, and U{sub 3}O{sub 8} powders in aqueous peroxide-carbonate solutions. Experimental parameters included; peroxide and carbonate concentrations, and temperature. Solution pH was varied with ammonium hydroxide. We will present details of the dissolution experiment set-up as well as information on the kinetics of dissolution of the various U-oxides as a function of the above variables. We will also discuss efforts to characterize solution and solid-state complexes in peroxide-carbonate systems. This study will demonstrate the applicability of peroxide-containing alkaline solutions for effectively dissolving SNF, and will enhance the current level of understanding of actinide behavior in peroxide-containing alkaline solutions. (authors)

  11. Adolescents' Explanations for Romantic Dissolutions: A Developmental Perspective

    Science.gov (United States)

    Connolly, Jennifer; McIsaac, Caroline

    2009-01-01

    Our objective was to examine the prevalence and developmental significance of romantic break-ups in adolescence, a relatively unexplored area of study. We examined their occurrence in a sample of 910 adolescents, first noting the frequency of these events across age, gender, and romantic experience, and then analyzing the dissolution explanations…

  12. FY 2000 Saltcake Dissolution and Feed Stability Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, R.D.; McGinnis, C.P.; Weber, C.F.; Welch, T.D.; Jewett, J.R.

    2000-07-31

    The Tanks Focus Area (TFA) continues to work closely with the Office of River Protection (ORP) to better understand the chemistry involved with the retrieval, transport, and pretreatment of nuclear wastes at Hanford. Since a private contractor is currently responsible for the pretreatment and immobilization activities in this remediation effort, the TFA has concentrated on saltcake dissolution and waste transport at the request of the ORP. Researchers at Hanford have performed a series of dissolution experiments on actual saltcake samples. Staff members at Mississippi State University (MSU) continue to model the dissolution results with the Environmental Simulation Program (ESP), which is used extensively by ORP personnel. Several ways to improve the predictive capabilities of the ESP were identified. Since several transfer lines at Hanford have become plugged, TFA tasks at AEA Technologies, Florida International University (FIU), MSU, and Oak Ridge National Laboratory (ORNL) are investigating the behavior of the supernatants and slurries during transport. A combination of experimental and theoretical techniques is used to study the transport chemistry. This effort is expected to develop process control tools for waste transfer. The results from these TFA tasks were presented to ORP personnel during the FY 2000 Saltcake Dissolution and Feed Stability Workshop, which was held on May 16-17 in Richland, Washington. The minutes from this workshop are provided in this report.

  13. CO2 dissolution in water using long serpentine microchannels

    OpenAIRE

    Cubaud, Thomas; Sauzade, Martin; SUN, RUOPENG

    2012-01-01

    The evolution of carbon dioxide bubbles dissolving in water is experimentally examined using long microchannels. We study the coupling between bubble hydrodynamics and dissolution in confined geometries. The gas impregnation process in liquid produces significant flow rearrangements. Depending on the initial volumetric liquid fraction, three operating regimes are identified, namely saturating, coalescing, and dissolving. The morphological and dynamical transition from segmented to dilute bubb...

  14. In vitro dissolution study of atorvastatin binary solid dispersion

    Science.gov (United States)

    Jahan, Rahat; Islam, Md. Saiful; Tanwir, Ahmad; Chowdhury, Jakir Ahmed

    2013-01-01

    The aim of the present study was to improve the solubility and dissolution rate of atorvastatin (ATV), a slight water-soluble drug, by solid dispersion (SD) technique using a hydrophilic carrier Poloxamer 188 (POL188). Physical mixing (PM) and solvent evaporation (SE) method were used to prepare ATV-SD where different drug-carrier ratios were used. Prepared formulations were characterized in their solid state by solubility study; differential scanning calorimetry, scanning electron microscopy, and Fourier transform infrared spectroscopy which demonstrated changes in the formulations supporting the improved solubility. Percent content of POL188 in the SD matrix was found to play the pivotal role in the improvement of dissolution property of ATV. In case of PM, highest enhancement in drug release was found for 1:3 ratio (P < 0.05, ANOVA Single factor) whereas in case of SE, 3:0.5 ratio of ATV-POL188 resulted the maximum enhancement in ATV release (P < 0.05, ANOVA Single factor). Analysis of dissolution data of optimized formula indicated the best fitting with Peppas-Korsmeyer model and the drug release kinetics was fickian diffusion. In conclusion, binary SD prepared by both PM and SE technique using POL188 could be considered as a simple, efficient method to prepare ATV solid dispersions with significant improvement in the dissolution rate. PMID:23662278

  15. In vitro dissolution study of atorvastatin binary solid dispersion

    Directory of Open Access Journals (Sweden)

    Rahat Jahan

    2013-01-01

    Full Text Available The aim of the present study was to improve the solubility and dissolution rate of atorvastatin (ATV, a slight water-soluble drug, by solid dispersion (SD technique using a hydrophilic carrier Poloxamer 188 (POL188. Physical mixing (PM and solvent evaporation (SE method were used to prepare ATV-SD where different drug-carrier ratios were used. Prepared formulations were characterized in their solid state by solubility study; differential scanning calorimetry, scanning electron microscopy, and Fourier transform infrared spectroscopy which demonstrated changes in the formulations supporting the improved solubility. Percent content of POL188 in the SD matrix was found to play the pivotal role in the improvement of dissolution property of ATV. In case of PM, highest enhancement in drug release was found for 1:3 ratio (P < 0.05, ANOVA Single factor whereas in case of SE, 3:0.5 ratio of ATV-POL188 resulted the maximum enhancement in ATV release (P < 0.05, ANOVA Single factor. Analysis of dissolution data of optimized formula indicated the best fitting with Peppas-Korsmeyer model and the drug release kinetics was fickian diffusion. In conclusion, binary SD prepared by both PM and SE technique using POL188 could be considered as a simple, efficient method to prepare ATV solid dispersions with significant improvement in the dissolution rate.

  16. Dissolution of Metal Supported Spent Auto Catalysts in Acids

    Directory of Open Access Journals (Sweden)

    Fornalczyk A.

    2016-03-01

    Full Text Available Metal supported auto catalysts, have been used in sports and racing cars initially, but nowadays their application systematically increases. In Metal Substrate (supported Converters (MSC, catalytic functions are performed by the Platinum Group Metals (PGM: Pt, Pd, Rh, similarly to the catalysts on ceramic carriers. The contents of these metals make that spent catalytic converters are valuable source of precious metals. All over the world there are many methods for the metals recovery from the ceramic carriers, however, the issue of platinum recovery from metal supported catalysts has not been studied sufficiently yet. The paper presents preliminary results of dissolution of spent automotive catalyst on a metal carrier by means of acids: H2SO4, HCl, HNO3, H3PO4. The main assumption of the research was the dissolution of base metals (Fe, Cr, Al from metallic carrier of catalyst, avoiding dissolution of PGMs. Dissolution was the most effective when concentrated hydrochloric acid, and 2M sulfuric acid (VI was used. It was observed that the dust, remaining after leaching, contained platinum in the level of 0.8% and 0.7%, respectively.

  17. Liquisolid tablets for dissolution enhancement of a hypolipidemic drug

    Directory of Open Access Journals (Sweden)

    D S Patel

    2015-01-01

    Full Text Available This investigation was aimed to improve the dissolution rate of the poorly soluble drug lovastatin, by formulating it as a liquisolid compact. Different liquisolid compacts were prepared using mathematical formulae to calculate the required quantities of powder and liquid ingredients to produce acceptably flowable and compressible admixture. Avicel PH 200, Cab-O-Sil, sodium starch glycolate and PEG 400 were employed as carrier, coating material, disintegrant and non-volatile liquid vehicle, respectively. The various drug to liquid and carrier to coating ratio were used to prepare liquisolid compacts. The formulated liquisolid tablets were evaluated for weight variation, hardness, drug content, friability and disintegration time. The in vitro release characteristics of the drug from tablets formulated by direct compression and liquisolid technique were compared in two different dissolution media. The tableting properties of the liquisolid compacts were within the acceptable limits and drug release rates were distinctly higher as compared to directly compressed tablets. The FTIR spectra showed no interaction between drug-excipient and disappearance of the characteristic absorption band of lovastatin in liquisolid formulations could be attributed to the formation of hydrogen bonding between the drug and liquid vehicle, which resulted in dissolution enhancement. Thus, the liquisolid technique was found to be a promising approach for improving the dissolution of a poorly soluble drug like lovastatin.

  18. Dissolution methodology for taste masked oral dosage forms.

    Science.gov (United States)

    Gittings, Sally; Turnbull, Neil; Roberts, Clive J; Gershkovich, Pavel

    2014-01-10

    Conventional adult dosage forms are often not suitable for the paediatric and geriatric populations due to either swallowing difficulties or patient repulsion and a requirement for tailored dosing to individual compliance or physiological needs. Alternative formulations are available; however these often require the incorporation of more complex taste masking techniques. One approach to taste masking is to reduce contact between the bitter Active Pharmaceutical Ingredient (API) and oral cavity taste bud regions. This is achieved by hindering release in the oral cavity, or including competitive inhibition of bitter sensation for example by using flavours or sweeteners. There may also be other sensational complications from the API such as residual burning, reflux or metallic taste sensations to deal with. In vitro dissolution testing is employed to elucidate taste masking capability by quantifying release of the drug in simulated oral cavity conditions. Dissolution testing approaches may also be used to potentially predict or quantify the effect of the taste masking technique on the resultant pharmacokinetic profile. The present review investigates the anatomy and physiology of the oral cavity and current approaches to taste masking. In vitro dissolution methodologies adopted in the evaluation of taste masked formulations are discussed for their relative merits and drawbacks. A vast array of methodologies has been employed, with little agreement between approaches, and a lack of biorelevance. Future directions in dissolution methodology such as TNO Intestinal Model (TIM) and the Artificial Stomach and Duodenum model (ASD) are also discussed.

  19. FORMULATION AND IN VITRO DISSOLUTION STUDIES OF SALBUTAMOL

    Directory of Open Access Journals (Sweden)

    Dr. G. Nageswara Rao et al

    2012-10-01

    Full Text Available Salbutamol is a potent anti-asthmatic agent, is a short-acting β2-adrenergic receptor agonist act. In the present study, an attempt has been made to prepare fast dissolving tablets of Salbutamol in the oral cavity with enhanced dissolution rate and to achieve better patient compliance. The tablets were prepared with four superdisintegrants e.g., Sodium starch glycolate, Cross-povidone, Cross-carmellose sodium, Pregelatinized starch by direct compression method. The pre-compression parameters of mixed blend were examined for angle of repose, bulk density, tapped density, Compressibility index and Hausner’s ratio. The tablets were evaluated for hardness, friability, weight variation, disintegration time, dissolution rate, content uniformity and drug content. It was concluded that the fast dissolving tablets with proper hardness, rapidly disintegrate with enhanced dissolution can be made using selected superdisintegrants. Among all formulations, batch D4 was considered as best since it showed enhanced dissolution, which leads to improved bioavailability, improved effectiveness and hence better patient compliance.

  20. The Baltimore and Utrecht models for cluster dissolution

    NARCIS (Netherlands)

    Lamers, H.J.G.L.M.

    2009-01-01

    The analysis of the age distributions of star cluster samples of different galaxies has resulted in two very different empirical models for the dissolution of star clusters: the Baltimore model and the Utrecht model. I describe these two models and their differences. The Baltimore model implies that

  1. A Dynamic Flux Dissolution Model for Oxygen Steelmaking

    Science.gov (United States)

    Kadrolkar, Ameya; Andersson, Nils Å. I.; Dogan, Neslihan

    2016-08-01

    A modified model for prediction of flux dissolution in oxygen steelmaking process is presented in this study. The aim of this paper is to introduce a procedure for simulating the amount of dissolved lime with respect to the saturation concentration of CaO by coupling the existing thermodynamic and kinetic models simultaneously. The procedure is developed to calculate the saturation concentrations/solubility of CaO in slag using thermodynamic models namely FactSage™, Cell Model, and Thermo-Calc™. Total amount of dissolved lime is evaluated by integrating solubility values in the rate equation of lime dissolution over time taking into account the effects of physical properties and temperature of slag and particle size of flux additions and validated against industrial data available in literature. Comparison between measured and calculated undissolved lime shows a good agreement between them using any thermodynamic models even though there are some differences in the predictions of saturation concentration of CaO in slag. It has been shown that two distinct control mechanisms for lime dissolution in BOF slags exist and consideration of the free lime-controlled mechanism is essential for accurate prediction of dissolution rate of lime in slag.

  2. Premarital Cohabitation and Marital Dissolution: An Examination of Recent Marriages

    Science.gov (United States)

    Manning, Wendy D.; Cohen, Jessica A.

    2012-01-01

    An ongoing question remains for family researchers: Why does a positive association between cohabitation and marital dissolution exist when one of the primary reasons to cohabit is to test relationship compatibility? Drawing on recently collected data from the 2006-2008 National Survey of Family Growth, the authors examined whether premarital…

  3. Role of natural convection in the dissolution of sessile droplets

    CERN Document Server

    Dietrich, Erik; Visser, Claas Willem; Hofhuis, Kevin; Kooij, E Stefan; Zandvliet, Harold J W; Lohse, Detlef

    2016-01-01

    The dissolution process of small (initial (equivalent) radius $R_0 Ra_t$, where $Ra_t = 12$ is the transition Ra-number as extracted from the data. For $Ra < Ra_t$ and smaller, convective transport is progressively overtaken by diffusion and the above scaling relations break down.

  4. Adolescent Sexuality and the Risk of Marital Dissolution

    Science.gov (United States)

    Paik, Anthony

    2011-01-01

    This research investigates whether first sexual intercourse during adolescence is associated with increased risk of first marriage dissolution and tests whether the results are consistent with causal or selection explanations. Drawing on a sample of 3,793 ever-married women from the 2002 National Survey of Family Growth, this study estimated…

  5. Adolescents' Explanations for Romantic Dissolutions: A Developmental Perspective

    Science.gov (United States)

    Connolly, Jennifer; McIsaac, Caroline

    2009-01-01

    Our objective was to examine the prevalence and developmental significance of romantic break-ups in adolescence, a relatively unexplored area of study. We examined their occurrence in a sample of 910 adolescents, first noting the frequency of these events across age, gender, and romantic experience, and then analyzing the dissolution explanations…

  6. Evaluation of a dynamic dissolution/permeation model

    DEFF Research Database (Denmark)

    Sironi, Daniel; Christensen, Mette; Rosenberg, Jörg

    2017-01-01

    Combined dissolution/permeation testing is gaining increasing attention as an in vitro tool for predictive performance ranking of enabling oral formulations. The current aim was to study how in vitro drug permeation evolves under conditions, where the donor concentration is changing (non-steady s......Combined dissolution/permeation testing is gaining increasing attention as an in vitro tool for predictive performance ranking of enabling oral formulations. The current aim was to study how in vitro drug permeation evolves under conditions, where the donor concentration is changing (non......-steady state). To this end, a model case was construed: compacts of pure crystalline hydrocortisone methanolate (HC·MeOH) of slow release rates were prepared, and their dissolution and permeation determined simultaneously in a side-by-side setup, separated by a biomimetic barrier (Permeapad...... dissolution rate and flux influenced each other. Interestingly, for all the dynamic scenarios, the incremental flux values obtained correlated nicely with the corresponding actual donor concentrations. Furthermore, donor depletion was tested using a HC solution. The dynamic interplay between decrease in donor...

  7. Challenges facing production grids

    Energy Technology Data Exchange (ETDEWEB)

    Pordes, Ruth; /Fermilab

    2007-06-01

    Today's global communities of users expect quality of service from distributed Grid systems equivalent to that their local data centers. This must be coupled to ubiquitous access to the ensemble of processing and storage resources across multiple Grid infrastructures. We are still facing significant challenges in meeting these expectations, especially in the underlying security, a sustainable and successful economic model, and smoothing the boundaries between administrative and technical domains. Using the Open Science Grid as an example, I examine the status and challenges of Grids operating in production today.

  8. Many Faces of Migrations

    Directory of Open Access Journals (Sweden)

    Milica Antić Gaber

    2013-12-01

    The title “Many faces of migration”, connecting contributions in this special issue, is borrowed from the already mentioned Gallup Institute’s report on global migration (Esipova, 2011. The guiding principle in the selection of the contributions has been their diversity, reflected also in the list of disciplines represented by the authors: sociology, geography, ethnology and cultural anthropology, history, art history, modern Mediterranean studies, gender studies and media studies. Such an approach necessarily leads not only to a diverse, but at least seemingly also incompatib

  9. Faced with a dilemma

    DEFF Research Database (Denmark)

    Christensen, Anne Vinggaard; Christiansen, Anne Hjøllund; Petersson, Birgit

    2013-01-01

    's legal right to choose TOP and considerations about the foetus' right to live were suppressed. Midwives experienced a dilemma when faced with aborted foetuses that looked like newborns and when aborted foetuses showed signs of life after a termination. Furthermore, they were critical of how physicians...... counsel women/couples after prenatal diagnosis. CONCLUSIONS: The midwives' practice in relation to late TOP was characterised by an acknowledgement of the growing ethical status of the foetus and the emotional reactions of the women/couples going through late TOP. Other professions as well as structural...

  10. A Model for Dissolution of Lime in Steelmaking Slags

    Science.gov (United States)

    Sarkar, Rahul; Roy, Ushasi; Ghosh, Dinabandhu

    2016-08-01

    In a previous study by Sarkar et al. (Metall. Mater. Trans. B 46B:961 2015), a dynamic model of the LD steelmaking was developed. The prediction of the previous model (Sarkar et al. in Metall. Mater. Trans. B 46B:961 2015) for the bath (metal) composition matched well with the plant data (Cicutti et al. in Proceedings of 6th International Conference on Molten Slags, Fluxes and Salts, Stockholm City, 2000). However, with respect to the slag composition, the prediction was not satisfactory. The current study aims to improve upon the previous model Sarkar et al. (Metall. Mater. Trans. B 46B:961 2015) by incorporating a lime dissolution submodel into the earlier one. From the industrial point of view, the understanding of the lime dissolution kinetics is important to meet the ever-increasing demand of producing low-P steel at a low basicity. In the current study, three-step kinetics for the lime dissolution is hypothesized on the assumption that a solid layer of 2CaO·SiO2 should form around the unreacted core of the lime. From the available experimental data, it seems improbable that the observed kinetics should be controlled singly by any one kinetic step. Accordingly, a general, mixed control model has been proposed to calculate the dissolution rate of the lime under varying slag compositions and temperatures. First, the rate equation for each of the three rate-controlling steps has been derived, for three different lime geometries. Next, the rate equation for the mixed control kinetics has been derived and solved to find the dissolution rate. The model predictions have been validated by means of the experimental data available in the literature. In addition, the effects of the process conditions on the dissolution rate have been studied, and compared with the experimental results wherever possible. Incorporation of this submodel into the earlier global model (Sarkar et al. in Metall. Mater. Trans. B 46B:961 2015) enables the prediction of the lime dissolution rate

  11. Investigation on characterization of Ereen coal deposit

    Directory of Open Access Journals (Sweden)

    S. Jargalmaa

    2016-03-01

    Full Text Available The Ereen coal deposit is located 360 km west from Ulaanbaatar and 95 km from Bulgan town. The coal reserve of this deposit is approximately 345.2 million tons. The Ereen coal is used directly for the Erdenet power plant for producing of electricity and heat. The utilization of this coal for gas and liquid product using gasification and pyrolysis is now being considered. The proximate and ultimate analysis show that the Ereen coal is low rank D mark hard coal, which corresponds to subbituminous coal. The SEM images of initial coal sample have compact solid pieces. The SEM image of carbonized and activated carbon samples are hard material with high developed macro porosity structure. The SEM images of hard residue after thermal dissolution in autoclave characterizes hard pieces with micro porous structure in comparison with activated carbon sample. The results of the thermal dissolution of Ereen coal in tetralin with constant weight ratio between coal and tetralin (1:1.8 at the 450ºC show that 38% of liquid product can be obtained by thermal decomposition of the COM (coal organic matter.Mongolian Journal of Chemistry 16 (42, 2015, 18-21

  12. Aging changes in the face

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/004004.htm Aging changes in the face To use the sharing ... face with age References Brodie SE, Francis JH. Aging and disorders of the eye. In: Fillit HM, ...

  13. Use of sodium polyaspartate for the removal of hydroxyapatite/brushite deposits from stainless steel tubing

    Energy Technology Data Exchange (ETDEWEB)

    Littlejohn, F.; Saez, A.E.; Grant, C.S. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Chemical Engineering

    1998-07-01

    This research investigates the use of sodium polyaspartate, a nontoxic, biodegradable polycarboxylic sequestrant, for removing calcium phosphate deposit consisting of hydroxyapatite (HAP) and brushite or dicalcium phosphate dihydrate (DCPD) from stainless steel surfaces. Cleaning studies show that the use of sodium polyaspartate under alkaline conditions significantly enhances the removal rates when compared to deionized water. In acidic solutions, sodium polyaspartate concentrations below 300 ppm inhibit removal of HAP/DCPD deposits whereas higher concentrations increase the removal rate. Comparative cleaning studies at alkaline pHs show that sodium polyaspartate cleans the surface at a rate comparable to sodium citrate but slower than in ethylenediaminetetraacetic acid. Supplementary dissolution experiments show that sodium polyaspartate enhances the HAP/DCPD dissolution rate while inhibiting the release of Ca{sup 2+}. On the basis of these findings, the authors have concluded that sodium polyaspartate improves the HAP/DCPD dissolution and cleaning rates by Ca{sup 2+} sequestration.

  14. Magnetic resonance imaging of clays: swelling, sedimentation, dissolution

    Science.gov (United States)

    Dvinskikh, Sergey; Furo, Istvan

    2010-05-01

    While most magnetic resonance imaging (MRI) applications concern medical research, there is a rapidly increasing number of MRI studies in the field of environmental science and technology. In this presentation, MRI will be introduced from the latter perspective. While many processes in these areas are similar to those addressed in medical applications of MRI, parameters and experimental implementations are often quite different and, in many respects, far more demanding. This hinders direct transfer of existing methods developed for biomedical research, especially when facing the challenging task of obtaining spatially resolved quantitative information. In MRI investigation of soils, clays, and rocks, mainly water signal is detected, similarly to MRI of biological and medical samples. However, a strong variation of water mobility and a wide spread of water spin relaxation properties in these materials make it difficult to use standard MRI approaches. Other significant limitations can be identified as following: T2 relaxation and probe dead time effects; molecular diffusion artifacts; varying dielectric losses and induced currents in conductive samples; limited dynamic range; blurring artifacts accompanying drive for increasing sensitivity and/or imaging speed. Despite these limitations, by combining MRI techniques developed for solid and liquid states and using independent information on relaxation properties of water, interacting with the material of interest, true images of distributions of both water, material and molecular properties in a wide range of concentrations can be obtained. Examples of MRI application will be given in the areas of soil and mineral research where understanding water transport and erosion processes is one of the key challenges. Efforts in developing and adapting MRI approaches to study these kinds of systems will be outlined as well. Extensive studies of clay/water interaction have been carried out in order to provide a quantitative

  15. Evaluation and comparison of in-vitro dissolution profiles for different ...

    African Journals Online (AJOL)

    EB

    Food and Medicine quality Control Laboratory, Food, Medicine and Healthcare ... However, the presences of generic products those are not interchangeable with that of the innovator and/or ... importance of dissolution tests and dissolution.

  16. Biorelevant characterisation of amorphous furosemide salt exhibits conversion to a furosemide hydrate during dissolution

    DEFF Research Database (Denmark)

    Nielsen, Line Hagner; Gordon, Sarah; Pajander, Jari Pekka

    2013-01-01

    , as well as of crystalline furosemide salt and acid showed a higher rate of dissolution of the salt forms in comparison with the two acid forms. The measured dissolution rates of the four furosemide forms from the UV imaging system and from eluted effluent samples were consistent with dissolution rates...... obtained from micro dissolution experiments. Partial least squares-discriminant analysis of Raman spectra of the amorphous acid form during flow through dissolution showed that the amorphous acid exhibited a fast conversion to the crystalline acid. Flow through dissolution coupled with Raman spectroscopy...... showed a conversion of the amorphous furosemide salt to a more stable polymorph. It was found by thermogravimetric analysis and hot stage microscopy that the salt forms of furosemide converted to a trihydrate during dissolution. It can be concluded that during biorelevant dissolution, the amorphous...

  17. FaceID: A face detection and recognition system

    Energy Technology Data Exchange (ETDEWEB)

    Shah, M.B.; Rao, N.S.V.; Olman, V.; Uberbacher, E.C.; Mann, R.C.

    1996-12-31

    A face detection system that automatically locates faces in gray-level images is described. Also described is a system which matches a given face image with faces in a database. Face detection in an Image is performed by template matching using templates derived from a selected set of normalized faces. Instead of using original gray level images, vertical gradient images were calculated and used to make the system more robust against variations in lighting conditions and skin color. Faces of different sizes are detected by processing the image at several scales. Further, a coarse-to-fine strategy is used to speed up the processing, and a combination of whole face and face component templates are used to ensure low false detection rates. The input to the face recognition system is a normalized vertical gradient image of a face, which is compared against a database using a set of pretrained feedforward neural networks with a winner-take-all fuser. The training is performed by using an adaptation of the backpropagation algorithm. This system has been developed and tested using images from the FERET database and a set of images obtained from Rowley, et al and Sung and Poggio.

  18. A novel thermal face recognition approach using face pattern words

    Science.gov (United States)

    Zheng, Yufeng

    2010-04-01

    A reliable thermal face recognition system can enhance the national security applications such as prevention against terrorism, surveillance, monitoring and tracking, especially at nighttime. The system can be applied at airports, customs or high-alert facilities (e.g., nuclear power plant) for 24 hours a day. In this paper, we propose a novel face recognition approach utilizing thermal (long wave infrared) face images that can automatically identify a subject at both daytime and nighttime. With a properly acquired thermal image (as a query image) in monitoring zone, the following processes will be employed: normalization and denoising, face detection, face alignment, face masking, Gabor wavelet transform, face pattern words (FPWs) creation, face identification by similarity measure (Hamming distance). If eyeglasses are present on a subject's face, an eyeglasses mask will be automatically extracted from the querying face image, and then masked with all comparing FPWs (no more transforms). A high identification rate (97.44% with Top-1 match) has been achieved upon our preliminary face dataset (of 39 subjects) from the proposed approach regardless operating time and glasses-wearing condition.e

  19. Enabling dynamics in face analysis

    NARCIS (Netherlands)

    Dibeklioğlu, H.

    2014-01-01

    Most of the approaches in automatic face analysis rely solely on static appearance. However, temporal analysis of expressions reveals interesting patterns. For a better understanding of the human face, this thesis focuses on temporal changes in the face, and dynamic patterns of expressions. In addit

  20. Forensic Face Recognition: A Survey

    NARCIS (Netherlands)

    Ali, Tauseef; Spreeuwers, Luuk; Veldhuis, Raymond; Quaglia, Adamo; Epifano, Calogera M.

    2012-01-01

    The improvements of automatic face recognition during the last 2 decades have disclosed new applications like border control and camera surveillance. A new application field is forensic face recognition. Traditionally, face recognition by human experts has been used in forensics, but now there is a

  1. Improvement of the dissolution rate of silymarin by means of solid dispersions

    Institute of Scientific and Technical Information of China (English)

    Li FQ; Hu JH

    2005-01-01

    Solid dispersions of silymarin were prepared by the fusion method with the intention of improving the dissolution properties of silymarin. Polyethylene glycol 6000 (PEG 6000) was used as the inert hydrophilic matrix. The dissolution studies of the solid dispersions were performed in vitro. And the results obtained showed that the dissolution rate of silymarin was considerably improved when formulated in solid dispersions with PEG 6000 as compared to original drug, and the increased dissolution rate might be favorable for further oral absorption.

  2. Characterization of phagolysosomal simulant fluid for study of beryllium aerosol particle dissolution.

    Science.gov (United States)

    Stefaniak, A B; Guilmette, R A; Day, G A; Hoover, M D; Breysse, P N; Scripsick, R C

    2005-02-01

    A simulant of phagolysosomal fluid is needed for beryllium particle dissolution research because intraphagolysosomal dissolution is believed to be a necessary step in the cellular immune response associated with development of chronic beryllium disease. Thus, we refined and characterized a potassium hydrogen phthalate (KHP) buffered solution with pH 4.55, termed phagolysosomal simulant fluid (PSF), for use in a static dissolution technique. To characterize the simulant, beryllium dissolution in PSF was compared to dissolution in the J774A.1 murine cell line. The effects of ionic composition, buffer strength, and the presence of the antifungal agent alkylbenzyldimethylammonium chloride (ABDC) on beryllium dissolution in PSF were evaluated. Beryllium dissolution in PSF was not different from dissolution in the J774A.1 murine cell line (p = 0.78) or from dissolution in another simulant having the same pH but different ionic composition (p = 0.73). A buffer concentration of 0.01-M KHP did not appear adequate to maintain pH under all conditions. There was no difference between dissolution in PSF with 0.01-M KHP and 0.02-M KHP (p = 0.12). At 0.04-M KHP, beryllium dissolution was increased relative to 0.02-M KHP (p = 0.02). Use of a 0.02-M KHP buffer concentration in the standard formulation for PSF provided stability in pH without alteration of the dissolution rate. The presence of ABDC did not influence beryllium dissolution in PSF (p = 0.35). PSF appears to be a useful and appropriate model of in vitro beryllium dissolution when using a static dissolution technique. In addition, the critical approach used to evaluate and adjust the composition of PSF may serve as a framework for characterizing PSF to study dissolution of other metal and oxide particles.

  3. Long shadows: a prospective study of predictors of relationship dissolution over 17 child-rearing years

    OpenAIRE

    Helland, Maren S; von Soest, Tilmann; Gustavson, Kristin; Røysamb, Espen; Mathiesen, Kristin S

    2014-01-01

    Background Parental relationship dissolutions have repeatedly been linked to negative outcomes for children, but predictors of parental dissolutions have been far less studied. Knowledge about parental dissolutions occurring after the early years of parenthood is especially sparse. The aim of the current study was to investigate whether a broad set of predictors from families of toddlers were associated with relationship dissolutions throughout the next 17 years of parentho...

  4. Carbonate mineral dissolution kinetics in high pressure experiments

    Science.gov (United States)

    Dethlefsen, F.; Dörr, C.; Schäfer, D.; Ebert, M.

    2012-04-01

    The potential CO2 reservoirs in the North German Basin are overlain by a series of Mesozoic barrier rocks and aquifers and finally mostly by Tertiary and Quaternary close-to-surface aquifers. The unexpected rise of stored CO2 from its reservoir into close-to-surface aquifer systems, perhaps through a broken well casing, may pose a threat to groundwater quality because of the acidifying effect of CO2 dissolution in water. The consequences may be further worsening of the groundwater quality due to the mobilization of heavy metals. Buffer mechanisms counteracting the acidification are for instance the dissolution of carbonates. Carbonate dissolution kinetics is comparably fast and carbonates can be abundant in close-to-surface aquifers. The disadvantages of batch experiments compared to column experiments in order to determine rate constants are well known and have for instance been described by v. GRINSVEN and RIEMSDIJK (1992). Therefore, we have designed, developed, tested, and used a high-pressure laboratory column system to simulate aquifer conditions in a flow through setup within the CO2-MoPa project. The calcite dissolution kinetics was determined for CO2-pressures of 6, 10, and 50 bars. The results were evaluated by using the PHREEQC code with a 1-D reactive transport model, applying a LASAGA (1984) -type kinetic dissolution equation (PALANDRI and KHARAKA, 2004; eq. 7). While PALANDRI and KHARAKA (2004) gave calcite dissolution rate constants originating from batch experiments of log kacid = -0.3 and log kneutral = -5.81, the data of the column experiment were best fitted using log kacid = -2.3 and log kneutral = -7.81, so that the rate constants fitted using the lab experiment applying 50 bars pCO2 were approximately 100 times lower than according to the literature data. Rate constants of experiments performed at less CO2 pressure (pCO2 = 6 bars: log kacid = -1.78; log kneutral = -7.29) were only 30 times lower than literature data. These discrepancies in the

  5. Deposit model for volcanogenic uranium deposits

    Science.gov (United States)

    Breit, George N.; Hall, Susan M.

    2011-01-01

    Volcanism is a major contributor to the formation of important uranium deposits both close to centers of eruption and more distal as a result of deposition of ash with leachable uranium. Hydrothermal fluids that are driven by magmatic heat proximal to some volcanic centers directly form some deposits. These fluids leach uranium from U-bearing silicic volcanic rocks and concentrate it at sites of deposition within veins, stockworks, breccias, volcaniclastic rocks, and lacustrine caldera sediments. The volcanogenic uranium deposit model presented here summarizes attributes of those deposits and follows the focus of the International Atomic Energy Agency caldera-hosted uranium deposit model. Although inferred by some to have a volcanic component to their origin, iron oxide-copper-gold deposits with economically recoverable uranium contents are not considered in this model.

  6. Face Processing: Models For Recognition

    Science.gov (United States)

    Turk, Matthew A.; Pentland, Alexander P.

    1990-03-01

    The human ability to process faces is remarkable. We can identify perhaps thousands of faces learned throughout our lifetime and read facial expression to understand such subtle qualities as emotion. These skills are quite robust, despite sometimes large changes in the visual stimulus due to expression, aging, and distractions such as glasses or changes in hairstyle or facial hair. Computers which model and recognize faces will be useful in a variety of applications, including criminal identification, human-computer interface, and animation. We discuss models for representing faces and their applicability to the task of recognition, and present techniques for identifying faces and detecting eye blinks.

  7. In situ dissolution analysis using coherent anti-Stokes Raman scattering (CARS) and hyperspectral CARS microscopy

    NARCIS (Netherlands)

    Fussell, Andrew; Garbacik, Erik; Offerhaus, Herman; Kleinebudde, Peter; Strachan, Clare

    2013-01-01

    The solid-state form of an active pharmaceutical ingredient (API) in an oral dosage form plays an important role in determining the dissolution rate of the API. As the solid-state form can change during dissolution, there is a need to monitor the oral dosage form during dissolution testing. Coherent

  8. Dissolution and Protection of Aluminium Oxide in Corrosive Aqueous Media - An Ellipsometry and Reflectometry Study

    NARCIS (Netherlands)

    Karlsson, P.M.; Postmus, B.R.; Palmqvist, A.E.C.

    2009-01-01

    Dissolution of alumina has been studied from wafers in aqueous solution by means of ellipsometry and reflectometry. It was discovered that the dissolution of aluminium oxide is promoted by ethanol amines like N,N-bis(2-hydroxyethyl)glycine and triethanolamine, and that this dissolution is retarded b

  9. Dissolution and Protection of Aluminium Oxide in Corrosive Aqueous Media - An Ellipsometry and Reflectometry Study

    NARCIS (Netherlands)

    Karlsson, P.M.; Postmus, B.R.; Palmqvist, A.E.C.

    2009-01-01

    Dissolution of alumina has been studied from wafers in aqueous solution by means of ellipsometry and reflectometry. It was discovered that the dissolution of aluminium oxide is promoted by ethanol amines like N,N-bis(2-hydroxyethyl)glycine and triethanolamine, and that this dissolution is retarded b

  10. Surface and bulk dissolution properties, and selectivity of DNA-linked nanoparticle assemblies

    NARCIS (Netherlands)

    Lukatsky, D.B.; Frenkel, D.

    2005-01-01

    Using a simple mean-field model, we analyze the surface and bulk dissolution properties of DNA-linked nanoparticle assemblies. We find that the dissolution temperature and the sharpness of the dissolution profiles increase with the grafting density of the single-stranded DNA "probes" on the surface

  11. 26 CFR 1.6043-3 - Return regarding liquidation, dissolution, termination, or substantial contraction of...

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 13 2010-04-01 2010-04-01 false Return regarding liquidation, dissolution... TAX (CONTINUED) INCOME TAXES Information Returns § 1.6043-3 Return regarding liquidation, dissolution... years preceding any liquidation, dissolution, termination, or substantial contraction of the...

  12. 31 CFR 315.83 - Reissue or payment on dissolution of corporation or partnership.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false Reissue or payment on dissolution of... and Officers § 315.83 Reissue or payment on dissolution of corporation or partnership. (a) Corporations. A bond registered in the name of a private corporation which is in the process of dissolution...

  13. 12 CFR 16.9 - Securities offered and sold in holding company dissolution.

    Science.gov (United States)

    2010-01-01

    ... dissolution. 16.9 Section 16.9 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY SECURITIES OFFERING DISCLOSURE RULES § 16.9 Securities offered and sold in holding company dissolution. Offers and sales of bank issued securities in connection with the dissolution of the holding company of...

  14. 26 CFR 301.6043-1 - Returns regarding liquidation, dissolution, termination, or contraction.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 18 2010-04-01 2010-04-01 false Returns regarding liquidation, dissolution... and Returns Returns and Records § 301.6043-1 Returns regarding liquidation, dissolution, termination... liquidations, dissolutions, terminations, or contracts, see §§ l.6043-1, 1.6043-2, and 1.6043-3 of this chapter...

  15. 26 CFR 1.6043-1 - Return regarding corporate dissolution or liquidation.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 13 2010-04-01 2010-04-01 false Return regarding corporate dissolution or... dissolution or liquidation. (a) Requirement of returns. Within 30 days after the adoption of any resolution or plan for or in respect of the dissolution of a corporation or the liquidation of the whole or any part...

  16. 31 CFR 353.83 - Reissue or payment on dissolution of corporation or partnership.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false Reissue or payment on dissolution of... Reissue or payment on dissolution of corporation or partnership. (a) Corporations. A bond registered in the name of a private corporation which is in the process of dissolution will be paid to the...

  17. Atmospheric Dissolved Iron Depostiion to the Global Oceans: Effects of Oxalate-Promoted Fe Dissolution, Photochemical Redox Cycling, and Dust Mineralogy

    Science.gov (United States)

    Johnson, M. S.; Meskhidze, N.

    2013-01-01

    Mineral dust deposition is suggested to be a significant atmospheric supply pathway of bioavailable iron (Fe) to Fe-depleted surface oceans. In this study, mineral dust and dissolved Fe (Fed) deposition rates are predicted for March 2009 to February 2010 using the 3-D chemical transport model GEOS-Chem implemented with a comprehensive dust-Fe dissolution scheme. The model simulates Fed production during the atmospheric transport of mineral dust taking into account inorganic and organic (oxalate)-promoted Fe dissolution processes, photochemical redox cycling between ferric (Fe(III)) and ferrous (Fe(II)) forms of Fe, dissolution of three different Fe-containing minerals (hematite, goethite, and aluminosilicates), and detailed mineralogy of windblown dust from the major desert regions. Our calculations suggest that during the yearlong simulation is approximately 0.26 Tg (1 Tg = 1012 g) of Fed was deposited to global oceanic regions. Compared to simulations only taking into account proton-promoted Fe dissolution, the addition of oxalate to the dust-Fe mobilization scheme increased total annual model-predicted Fed deposition to global oceanic regions by approximately 75%. The implementation of Fe(II)/Fe(III) photochemical redox cycling in the model allows for the distinction between different oxidation states of deposited Fed. Our calculations suggest that during the daytime, large fractions of Fed deposited to the global oceans is likely to be in Fe(II) form, while nocturnal fluxes of Fed are largely in Fe(III) form. Model simulations also show that atmospheric fluxes of Fed can be strongly influenced by the mineralogy of Fe-containing compounds. This study shows that Fed deposition to the oceans is controlled by total dust-Fe mass concentrations, mineralogy, the surface area of dust particles, atmospheric chemical composition, cloud processing, and meteorological parameters and exhibits complex and spatiotemporally variable patterns. Our study suggests that the

  18. Facing the Challenges

    DEFF Research Database (Denmark)

    He, Kai

    2014-01-01

    China's rise signifies a gradual transformation of the international system from unipolarity to a non-unipolar world. ,4s an organization of small and middle powers, ASEAN faces strategic uncertainties brought about by the power transition in the system. Deepening economic interdependence between...... ASEAN and China has amplified the economic cost for the ASEAN states to use traditional military means to deal with China s rise. Applying institutional balancing theory, this paper examines how ASEAN has adopted various institutional instruments, such as the ASEAN Regional Forum (ARF), the East Asia...... Summit (EAS), the Regional Comprehensive Economic Partnership (RCEP), and the ASEAN Community, to constrain and shape China's behaviour in the region in the post-Cold War era. It argues that due to globalization and economic interdependence, the power transition in the 21st century is different from...

  19. Préface

    Directory of Open Access Journals (Sweden)

    Marguerite Mendell

    2008-12-01

    Full Text Available C’est avec grand plaisir que je contribue la préface de ce numéro d’Interventions économiques dédié à la pertinence de la pensée de Karl Polanyi au début du 21ème siècle. Je suis très reconnaissante aux éditeurs, Diane Gabrielle Tremblay, Jean-Marc Fontan et Jean Louis Laville d’avoir pris l’initiative de préparer ce numéro pour le 11ème colloque international de l’Institut Karl Polanyi, qui correspond aussi au 20ème anniversaire de l’Institut, établi à l’Université Concordia en 1988. Interve...

  20. Removal of asphaltene and paraffin deposits using micellar solutions and fused reactions. Final report, 1995--1997

    Energy Technology Data Exchange (ETDEWEB)

    Chang, C.L.; Nalwaya, V.; Singh, P.; Fogler, H.S.

    1998-05-01

    Chemical treatments of paraffin and asphaltene deposition by means of cleaning fluids were carried out in this research project. Research focused on the characterization of asphaltene and paraffin materials and dissolution of asphaltene and paraffin deposits using surfactant/micellar fluids developed early in the project. The key parameters controlling the dissolution rate were identified and the process of asphaltene/paraffin dissolution were examined using microscopic apparatus. Numerical modeling was also carried out to understand the dissolution of paraffin deposits. The results show that fused chemical reaction systems are a promising way of removing paraffin deposits in subsea pipelines. The fused system may be in the form of alternate pulses, emulsions systems or encapsulated catalyst systems. Fused reaction systems, in fact, are extremely cost-effective--less than 10% of the cost of replacing entire sections of the blocked pipeline. The results presented in this report can have a real impact on the petroleum industry and the National Oil Program, if it is realized that the remediation technologies developed here can substantially delay abandonment (due to asphaltene/paraffin plugging) of domestic petroleum resources. The report also sheds new light on the nature and properties of asphaltenes and paraffin deposits which will ultimately help the scientific and research community to develop effective methods in eliminating asphaltene/paraffin deposition problems. It must also be realized that asphaltene remediation technologies developed and presented in this report are a real alternative to aromatic cleaning fluids currently used by the petroleum industry.

  1. [Comparative studies of face recognition].

    Science.gov (United States)

    Kawai, Nobuyuki

    2012-07-01

    Every human being is proficient in face recognition. However, the reason for and the manner in which humans have attained such an ability remain unknown. These questions can be best answered-through comparative studies of face recognition in non-human animals. Studies in both primates and non-primates show that not only primates, but also non-primates possess the ability to extract information from their conspecifics and from human experimenters. Neural specialization for face recognition is shared with mammals in distant taxa, suggesting that face recognition evolved earlier than the emergence of mammals. A recent study indicated that a social insect, the golden paper wasp, can distinguish their conspecific faces, whereas a closely related species, which has a less complex social lifestyle with just one queen ruling a nest of underlings, did not show strong face recognition for their conspecifics. Social complexity and the need to differentiate between one another likely led humans to evolve their face recognition abilities.

  2. The Effect of Pressure Dissolution and Precipitation on Fracture Permeability and Normal Stiffness

    Science.gov (United States)

    Zimmerman, R. W.; Lang, P. S.; Paluszny, A.

    2015-12-01

    Mechanically-chemically mediated processes may significantly alter the morphology of rock fracture surfaces. These processes may occur either as diagenetic mechanisms over geologic timescales under in situ-conditions, or during man-made engineering processes, during which injected fluids and/or induced temperature changes can significantly accelerate these processes. Numerical simulations at the grain scale have been conducted to predict the changes in normal stiffness and transmissivity of fractures under the combined processes of pressure dissolution and free-face precipitation. The ensuing compaction mechanism is characterized by dissolution of asperities under contact, and subsequent re-precipitation of the dissolved mass over the adjacent free surfaces. The normal stiffness of the fracture increases over time, due the increase in total contact area, and an increase in the number of regions in contact. The resultant stiffness curves reflect two regimes. At low loads, contact occurs primarily over the dissolved and precipitated, smoothened surface contact region, leading to rapid, exponential-like stiffening. At high loads, previously free-surface regions are brought into contact, and their unaltered rough nature results in the traditional, linear stiffening with increasing compression. The transition between the two contact regimes is approximately given by the confining pressure acting during the compaction process. During the compaction process, a steady decline of the hydraulic transmissivity is observed, due to both the decrease in mean aperture, and the increased tortuosity caused by the additional contact regions, up to the point at which the contact zones percolate and effectively seal the fracture hydraulically. The remaining fracture porosity is hydraulically ineffective, but may be as high as a third of the initial value. It follows that both the magnitude and nature of the predicted stiffness curves differ fundamentally from those observed for

  3. Micromorphology of modern tills in southwestern Spitsbergen – insights into depositional and post-depositional processes

    Directory of Open Access Journals (Sweden)

    Skolasińska Katarzyna

    2016-12-01

    Full Text Available Textural properties and microstructures are commonly used properties in the analysis of Pleistocene and older glacial deposits. However, contemporary glacial deposits are seldom studied, particularly in the context of post-depositional changes. This paper presents the results of a micromorphological study of recently deposited tills in the marginal zones of Hansbreen and Torellbreen, glaciers in southwestern Spitsbergen. The main objectives of this study were to compare modern tills deposited in subglacial and supraglacial conditions, as well as tills that were freshly released from ice with those laid down several decades ago. The investigated tills are primarily composed of large clasts of metamorphic rocks and represent coarse-grained, matrix-supported diamictons. The tills reveal several characteristic features for ductile (e.g. turbate structures and brittle (e.g. lineations, microshears deformations, which have been considered to be indicative of subglacial conditions. In supraglacial tills, the same structures are common as in the subglacial deposits, which points to the preservation of the primary features, though the sediment was transferred up to the glacier surface due to basal ice layer deformation and redeposited as slumps, or to formation of similar structures due to short-distance sediment re-deposition by mass flows. This study revealed that it might not be possible to distinguish subglacial and supraglacial tills on the basis of micromorphology if the latter are derived from a subglacial position. The only noted difference was the presence of iron oxide cementation zones and carbonate dissolution features in supraglacial tills. These features were found in tills that were deposited at least a few years ago and are interpreted to be induced by early post-depositional processes involving porewater/sediment interactions.

  4. Dust deposition: iron source or sink? A case study

    Directory of Open Access Journals (Sweden)

    Y. Ye

    2011-08-01

    Full Text Available A significant decrease of dissolved iron (DFe concentration has been observed after dust addition into mesocosms during the DUst experiment in a low Nutrient low chlorophyll Ecosystem (DUNE, carried out in the summer of 2008. Due to low biological productivity at the experiment site, biological consumption of iron can not explain the magnitude of DFe decrease. To understand processes regulating the observed DFe variation, we simulated the experiment using a one-dimensional model of the Fe biogeochemical cycle, coupled with a simple ecosystem model. Different size classes of particles and particle aggregation are taken into account to describe the particle dynamics. DFe concentration is regulated in the model by dissolution from dust particles and adsorption onto particle surfaces, biological uptake, and photochemical mobilisation of particulate iron.

    The model reproduces the observed DFe decrease after dust addition well. This is essentially explained by particle adsorption and particle aggregation that produces a high export within the first 24 h. The estimated particle adsorption rates range between the measured adsorption rates of soluble iron and those of colloidal iron, indicating both processes controlling the DFe removal during the experiment. A dissolution timescale of 3 days is used in the model, instead of an instantaneous dissolution, underlining the importance of dissolution kinetics on the short-term impact of dust deposition on seawater DFe.

    Sensitivity studies reveal that initial DFe concentration before dust addition was crucial for the net impact of dust addition on DFe during the DUNE experiment. Based on the balance between abiotic sinks and sources of DFe, a critical DFe concentration has been defined, above which dust deposition acts as a net sink of DFe, rather than a source. Taking into account the role of excess iron binding ligands and biotic processes, the critical DFe concentration might be applied to

  5. Reductive diagenesis, magnetite dissolution, greigite growth and paleomagnetic smoothing in marine sediments: A new view

    Science.gov (United States)

    Rowan, Christopher J.; Roberts, Andrew P.; Broadbent, Thomas

    2009-01-01

    In many anoxic sedimentary environments, the onset of sulfate reduction, and pyritization of detrital iron-bearing minerals, leads to a precipitous decline in magnetic mineral concentration during early diagenesis. The usefulness of the surviving paleomagnetic record in such environments is usually argued to depend on how much of the primary detrital magnetic assemblage survives diagenetic dissolution. Detailed rock magnetic and electron microscope analyses of rapidly deposited (~ 7 cm/kyr) latest Pleistocene-Holocene sediments from the continental margins of Oman (22°22.4'N, 60°08.0'E) and northern California (38°24.8'N, 123°58.2'W) demonstrate that pyritization during early diagenesis also leads to the progressive down-core growth of the ferrimagnetic iron sulfide greigite. Greigite growth begins with nucleation of large concentrations of superparamagnetic (SP) nanoparticles at the inferred position of the sulfate-methane transition, which can explain the apparently paradoxical suggestion that diagenetically reduced sediments contain enhanced concentrations of SP particles. Looping of hysteresis parameters on a "Day" plot records the dissolution of single domain (SD) (titano-)magnetite and the formation of SP greigite, which then slowly and progressively grows through its SD blocking volume and acquires a stable paleomagnetic signal. This looping trend is also evident in data from several published records (Oregon margin, Korea Strait, Japan Sea, Niger Fan, Argentine margin, and the Ontong-Java Plateau), indicating that these processes may be widespread in reducing environments. Our observations have profound implications for paleomagnetic records from sulfate-reducing environments. The paleomagnetic signal recorded by greigite is offset from the age of the surrounding sediments by 10's of kyr, and ongoing growth of greigite at depth results in smoothing of the recorded signal over intervals of 10's to 100's of kyr. We therefore expect the presence of

  6. Dissolution Behavior and Content Uniformity of An Improved Tablet Formulation Assayed by Spectrofluorometric and RIA Methods

    Directory of Open Access Journals (Sweden)

    Morteza Rafiee-Tehrani

    1990-06-01

    Full Text Available Digoxin 0.25 mg tablets were manufactured by pregranulation of lactose-fcorn starch with 10% corn starch paste and deposition of solvent on pregranules to make digoxin granules. In the preparation of tablet A, granules of lactose-corn Starch was uniformly moistened with a 5% chloroform-ethanol solution (2:lv/vof digoxin by a simple blending. Tablet B was produced by spray granulation system on which the solvent was sprayed on the granules of lactose-corn starch by utilization of a laboratory size fluidized bed drier (Uniglatt . The content uniformity and dissolution of both tablets were determined by the spectrofluorometric and radio¬immunoassay (RIA method modified for the assay of tablet solutious. One available commercially brand of digoxin tablet (C was included in dissolution study for comparison. For the spectrofluorometric method the technique is based on the fluor-ometric measurenent of the dehydration product of the cardiotonic steroid resulting from its reaction with hydrogen peroxide in concentrated hydrochloric acid. For the RIA method, the filtrate was diluted to theoretical concentration of 2.5 ng/ml."nAliquots of this dilution were then assayed for digoxin content using a commercial digoxin125 I RIA kit. Results from both assay methods were extrapolated to the total tablet content and compared with the labeled amount of 20 individual tablets. All tablet assay results were within the USP standards for the content uniformity and"ndissolution of individual. The individual tablet deviations from labeled amount by RIA method were smaller when compared with the spectrofluorometric method.There was no significant difference between the release of digoxin from three products, and thus it is suggested that the Procedure B could be easily applied for manufacturing"nof digoxin tablets in industrial scales.It was also concluded that,the RIA method could be used for the digoxin tablet determination.

  7. Comparing Face Detection and Recognition Techniques

    OpenAIRE

    Korra, Jyothi

    2016-01-01

    This paper implements and compares different techniques for face detection and recognition. One is find where the face is located in the images that is face detection and second is face recognition that is identifying the person. We study three techniques in this paper: Face detection using self organizing map (SOM), Face recognition by projection and nearest neighbor and Face recognition using SVM.

  8. Dissolution, corrosion and environmental issues in chemical mechanical planarization of copper

    Science.gov (United States)

    Tamilmani, Subramanian

    Chemical mechanical polishing (CMP) of dielectric and metal films has become a key process in manufacturing devices with ultra large scale integration (ULSI). In a CMP process, planarization is achieved by polishing a wafer with uneven topography using colloidal slurry consisting of sub-micron sized abrasive particles, oxidant and various additives. Hydrogen peroxide and hydroxylamine are commonly used oxidants in copper CMP process. To achieve planarization, the low lying areas have to be protected while the higher areas are polished away. This requires low static dissolution rate of copper in low areas. Another major issue in copper CMP is galvanic corrosion during barrier polishing step where both copper and the barrier metal are exposed to the slurry. The main goal of the research reported in this dissertation is to understand the dissolution and corrosion issues during the removal of copper in hydroxylamine based chemistries. Electrochemical and physical methods such as profilometry were used to obtain copper removal rates. Among the variety of organic compound tested, benzotriazole and salicylhydroxamic acid were identified as potential corrosion inhibitors for copper. The passive film formed on the copper surface by the addition of benzotriazole and salicylhydroxamic acid was characterized by X-ray photoelectron spectroscopy and atomic force microscopy. The passivation and repassivation kinetics were investigated in detail and a passivation mechanism for copper in hydroxylamine in the presence of benzotriazole and salicylhydroxamic acid chemistries is proposed. Copper removal experiments were performed on a specially designed electrochemical abrasion cell (EC-AC) in the presence and absence of inhibitors. The effect of anodic potentials on the dissolution of copper in various chemistries was studied to identify suitable conditions for electro-chemical mechanical planarization process. The extent of galvanic corrosion between copper and tantalum was estimated

  9. Elektronická komunikace vs. komunikace face to face

    OpenAIRE

    Pipková, Zuzana

    2009-01-01

    This thesis deals with new forms of communication particularly electronic ones. The main goal is to distinguish electronic communication from face to face communication in a way that differs from traditional media theories. By using examples of the most important medium in electronic communication, Internet, it is shown that nowadays we have such forms of electronic communication that surpass the traditional classification of oral/written communication, immediate/mediate communication, face t...

  10. The dissolution of kaolin by acidic fluoride wastes

    DEFF Research Database (Denmark)

    Kau, P. M. H.; Smith, D. W.; Binning, Philip John

    1997-01-01

    The potential use of kaolin as a lining material for the storage of acidic and acidic fluoride wastes is investigated, No significant changes are observed gravimetrically or structurally for kaolin soaked under acidic conditions down to pH 2 for periods up to 90 days, Some release of aluminium...... was noted with decreasing pH, Severe kaolin dissolution was apparent, however, when soaked in solutions less than pH 3 to 4 with a fluoride concentration of 0.05 M. Aluminium-oxygen bonding in kaolin appears to be substantially more prone to hydrofluoric acid attack than does silicon-oxygen bonding......, resulting in a preferential release of aluminium over silicon into solution. The solution pH was found to decrease with the dissolution reaction as fluorosilicic acid was produced during the kaolin breakdown....

  11. Polymeric Nanosuspensions for Enhanced Dissolution of Water Insoluble Drugs

    Directory of Open Access Journals (Sweden)

    Roya Yadollahi

    2013-01-01

    Full Text Available The aim of the present research is to formulate and evaluate polymeric nanosuspensions containing three model water insoluble drugs, nifedipine (NIF, carbamazepine (CBZ, and ibuprofen (IBU with various physicochemical properties. The nanosuspensions were prepared from hydroxypropyl methylcellulose (HPMC and polyvinylpyrrolidone (PVP by a cosolvent technique with polyethylene glycol (PEG-300 and water as the cosolvents. Physicochemical and morphological characteristics of the nanosuspensions (particle size, polydispersity index, and crystallinity have been correlated with the drug release behaviour. The effects of polymer, drug ratio on the physical, morphological, and dissolution characteristics of the drugs are reported. Drug release is significantly enhanced from the nanosuspensions; for example, the maximum NIF, IBU, and CBZ concentrations after 8-hour dissolution are increased approximately 37, 2, and 1.2 times, respectively, in comparison with the pure powdered drugs. Based on this solubilization enhancement performance, the nanosuspensions have potential for increasing the orally dosed bioavailability of NIF, IBU, and CBZ.

  12. Carbide Dissolution during Intercritical Austenitization in Bearing Steel

    Institute of Scientific and Technical Information of China (English)

    LI Hui; MI Zhenli; ZHANG Xiaolei; TANG Di; WANG Yide

    2014-01-01

    In order to investigate the carbide dissolution mechanism of high carbon-chromium bearing steel during the intercritical austenitization, the database of TCFE7 of Thermo-calc and MOBFE of DICTRA software were used to calculate the elements diffusion kinetic and the evolution law of volume fraction of carbide. DIL805A dilatometer was used to simulate the intercritical heat treatment. The microstructure was observed by scanning electron microscopy(SEM), and the micro-hardness was tested. The experimental results indicate that the dissolution of carbide is composed of two stages:initial austenite growth governed by carbon diffusion which sharply moves up the micro-hardness of quenched martensite, and subsequent growth controlled by diffusion of Cr elements in M3C. The volume fraction of M3C decreases with the increasing holding time, and the metallographic analysis shows a great agreement with values calculated by software.

  13. Parents' Union Dissolution and Adolescents' School Performance: Comparing Methodological Approaches.

    Science.gov (United States)

    Frisco, Michelle L; Muller, Chandra; Frank, Kenneth

    2007-08-01

    We use data from the National Longitudinal Study of Adolescent Health and the Adolescent Health and Academic Achievement Study to estimate how parents' union dissolution influences changes in adolescents' mathematics course work gains, overall grade point average, and course failure rates during a window of approximately 1 year (N = 2,629). A primary purpose of this study is demonstrating the utility of propensity score matching techniques for studying topics such as ours that pose methodological challenges such as dealing with endogeneity and selection bias. We compare propensity score matching techniques to ordinary least squares (OLS) regression methods to show and discuss comparability of results obtained using these different procedures. Findings suggest that associations between parents' union dissolution and achievement may be causal, regardless of method used.

  14. CO(2) dissolution in water using long serpentine microchannels.

    Science.gov (United States)

    Cubaud, Thomas; Sauzade, Martin; Sun, Ruopeng

    2012-06-01

    The evolution of carbon dioxide bubbles dissolving in water is experimentally examined using long microchannels. We study the coupling between bubble hydrodynamics and dissolution in confined geometries. The gas impregnation process in liquid produces significant flow rearrangements. Depending on the initial volumetric liquid fraction, three operating regimes are identified, namely saturating, coalescing, and dissolving. The morphological and dynamical transition from segmented to dilute bubbly flows is investigated. Tracking individual bubbles along the flow direction is used to calculate the temporal evolution of the liquid volumetric fraction and the average flow velocity near reference bubbles over long distances. This method allows us to empirically establish the functional relationship between bubble size and velocity. Finally, we examine the implication of this relationship during the coalescing flow regime, which limits the efficiency of the dissolution process.

  15. Pretreatment of rice hulls by ionic liquid dissolution.

    Science.gov (United States)

    Lynam, Joan G; Reza, M Toufiq; Vasquez, Victor R; Coronella, Charles J

    2012-06-01

    As a highly available waste product, rice hulls could be a starting block in replacing liquid fossil fuels. However, their silica covering can make further use difficult. This preliminary study investigates effects of dissolving rice hulls in the ionic liquids 1-ethyl-3-methylimidazolium acetate (EMIM Ac), 1-hexyl-3-methylimidazolium chloride, (HMIM Cl), and 1-allyl-3-methylimidazolium chloride (AMIM Cl), and what lignocellulosic components can be precipitated from the used ionic liquid with water and ethanol. EMIM Ac dissolution at 110 °C for 8 h was found to completely remove lignin from rice hulls, while ethanol was capable of precipitating lignin out of the used EMIM Ac. With 8h dissolution at 110 °C using HMIM Cl, approximately 20% of the cellulose in the rice hull sample can be precipitated out using water as co-solvent, while more than 60% of the hemicellulose can be precipitated with ethanol.

  16. Spiking Neural P Systems with Neuron Division and Dissolution

    Science.gov (United States)

    Liu, Xiyu; Wang, Wenping

    2016-01-01

    Spiking neural P systems are a new candidate in spiking neural network models. By using neuron division and budding, such systems can generate/produce exponential working space in linear computational steps, thus provide a way to solve computational hard problems in feasible (linear or polynomial) time with a “time-space trade-off” strategy. In this work, a new mechanism called neuron dissolution is introduced, by which redundant neurons produced during the computation can be removed. As applications, uniform solutions to two NP-hard problems: SAT problem and Subset Sum problem are constructed in linear time, working in a deterministic way. The neuron dissolution strategy is used to eliminate invalid solutions, and all answers to these two problems are encoded as indices of output neurons. Our results improve the one obtained in Science China Information Sciences, 2011, 1596-1607 by Pan et al. PMID:27627104

  17. Mathematical modeling of precipitation and dissolution reactions in microbiological systems.

    Science.gov (United States)

    Rittmann, Bruce E; Banaszak, James E; VanBriesen, Jeanne M; Reed, Donald T

    2002-01-01

    We expand the biogeochemical model CCBATCH to include a precipitation/dissolution sub-model that contains kinetic and equilibrium options. This advancement extends CCBATCH's usefulness to situations in which microbial reactions cause or are affected by formation or dissolution of a solid phase. The kinetic option employs a rate expression that explicitly includes the intrinsic kinetics for reaction or mass-transport control, the difference from thermodynamic equilibrium, and the aqueous concentration of the rate-limiting metal or ligand. The equilibrium feature can be used alone, and it also serves as check that the kinetic rate never is too fast and "overshoots" equilibrium. The features of the expanded CCBATCH are illustrated by an example in which the precipitation of Fe(OH)3(s) allows the biodegradation of citric acid, even though complexes are strong and not bioavailable. Precipitation releases citrate ligand, and biodegradation of the citrate increases the pH.

  18. Bone Substitute Fabrication Based on Dissolution-Precipitation Reactions

    Directory of Open Access Journals (Sweden)

    Kunio Ishikawa

    2010-02-01

    Full Text Available Although block- or granular-type sintered hydroxyapatite are known to show excellent tissue responses and good osteoconductivity, apatite powder elicits inflammatory response. For the fabrication of hydroxyapatite block or granules, sintering is commonly employed. However, the inorganic component of bone and tooth is not high crystalline hydroxyapatite but low crystalline B-type carbonate apatite. Unfortunately, carbonate apatite powder cannot be sintered due to its instability at high temperature. Another method to fabricate apatite block and/or granule is through phase transformation based on dissolution-precipitation reactions using a precursor phase. This reaction basically is the same as a setting and hardening reaction of calcium sulfate or plaster. In this paper, apatite block fabrication methods by phase transformation based on dissolution-precipitation reactions will be discussed, with a focus on the similarity of the setting and hardening reaction of calcium sulfate.

  19. Marital Dissolution in Japan: Recent Trends and Patterns

    Directory of Open Access Journals (Sweden)

    Miho Iwasawa

    2004-12-01

    Full Text Available Very little is known about recent trends in divorce in Japan. In this paper, we use Japanese vital statistics and census data to describe trends in the experience of marital dissolution across the life course, and to examine change over time in educational differentials in divorce. Cumulative probabilities of marital dissolution have increased rapidly across successive marriage cohorts over the past twenty years, and synthetic period estimates suggest that roughly one-third of Japanese marriages are now likely to end in divorce. Estimates of educational differentials also indicate a rapid increase in the extent to which divorce is concentrated at lower levels of education. While educational differentials were negligible in 1980, by 2000, women who had not gone beyond high school were far more likely to be divorced than those with more education.

  20. Holistic crowding of Mooney faces.

    Science.gov (United States)

    Farzin, Faraz; Rivera, Susan M; Whitney, David

    2009-06-29

    An object or feature is generally more difficult to identify when other objects are presented nearby, an effect referred to as crowding. Here, we used Mooney faces to examine whether crowding can also occur within and between holistic face representations (C. M. Mooney, 1957). Mooney faces are ideal stimuli for this test because no cues exist to distinguish facial features in a Mooney face; to find any facial feature, such as an eye or a nose, one must first holistically perceive the image as a face. Through a series of six experiments we tested the effect of crowding on Mooney face recognition. Our results demonstrate crowding between and within Mooney faces and fulfill the diagnostic criteria for crowding, including eccentricity dependence and lack of crowding in the fovea, critical flanker spacing consistent with less than half the eccentricity of the target, and inner-outer flanker asymmetry. Further, our results show that recognition of an upright Mooney face is more strongly impaired by upright Mooney face flankers than inverted ones. Taken together, these results suggest crowding can occur selectively between high-level representations of faces and that crowding must occur at multiple levels in the visual system.