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Sample records for carrier element-free coprecipitation

  1. Carrier element-free coprecipitation (CEFC) method for the separation, preconcentration and speciation of chromium using an isatin derivative.

    PubMed

    Bulut, Volkan Numan; Ozdes, Duygu; Bekircan, Olcay; Gundogdu, Ali; Duran, Celal; Soylak, Mustafa

    2009-01-19

    A new, simple, rapid and sensitive separation, preconcentration and speciation procedure for chromium in environmental liquid and solid samples has been established. The present speciation procedure for Cr(III) and Cr(VI) is based on combination of carrier element-free coprecipitation (CEFC) and flame atomic absorption spectrometric (FAAS) determinations. In this method a newly synthesized organic coprecipitant, 5-chloro-3-[4-(trifluoromethoxy) phenylimino]indolin-2-one (CFMEPI), was used without adding any carrier element for coprecipitation of chromium(III). After reduction of chromium(VI) by concentrated H(2)SO(4) and ethanol, the procedure was applied for the determination of total chromium. Chromium(VI) was calculated as the difference between the amount of total chromium and chromium(III). The optimum conditions for coprecipitation and speciation processes were investigated on several commonly tested experimental parameters, such as pH of the solution, amount of coprecipitant, sample volume, etc. No considerable interference was observed from the other investigated anions and cations, which may be found in natural water samples. The preconcentration factor was found to be 40. The detection limit for chromium(III) corresponding to three times the standard deviation of the blank (N=10) was found 0.7 microg L(-1). The present procedure was successfully applied for speciation of chromium in several liquid and solid environmental samples. In order to support the accuracy of the method, the certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) were analyzed, and standard APDC-MIBK liquid-liquid extraction method was performed. The results obtained were in good agreement with the certified values. PMID:19100880

  2. Application of carrier element free coprecipitation (CEFC) method for determination of Co(II), Cu(II) and Ni(II) ions in food and water samples.

    PubMed

    Serencam, Huseyin; Duran, Celal; Ozdes, Duygu; Bektas, Hakan

    2013-01-01

    A simple and highly sensitive separation and preconcentration procedure, which has minimal impact on the environment, has been developed. The procedure is based on the carrier element free coprecipitation (CEFC) of Co(II), Cu(II), and Ni(II) ions by using 2-{4-[2-(1H-indol-3-yl)ethyl]-3-(4-methylbenzyl)-5-oxo-4,5-dihydro- 1H-1,2,4-triazol-l-yl}-N'-(pyridin-2-yl methylidene)acetohydrazide (IMOTPA), as an organic coprecipitant. The levels of analyte ions were determined by flame atomic absorption spectrometry (FAAS). The detection limits for Co(II), Cu(II) and Ni(II) ions were found to be 0.40, 0.16 and 0.17 microg L(-1), respectively, and the relative standard deviations for the analyte ions were lower than 3.0%. Spike tests and certified reference material analyses were performed to validate the method. The method was successfully applied for the determination of Co(II), Cu(II) and Ni(II) ions levels in sea and stream water as liquid samples and red pepper, black pepper, and peppermint as solid samples. PMID:23878931

  3. A new coprecipitation method without carrier element for separation and preconcentration of some metal ions at trace levels in water and food samples.

    PubMed

    Gouda, Ayman A

    2016-01-01

    A new simple and sensitive preconcentration, separation and environmentally friendly method based on carrier element free coprecipitation (CEFC) was developed using 4-(2-hydroxybenzylideneamino)-1,2-dihydro-2,3-dimethyl-1-phenylpyrazol-5-one (APSAL) as a new organic co-precipitant to precipitate Cr(3+), Cu(2+), Fe(3+), Pb(2+) and Zn(2+) ions from water and food samples. The levels of the studied elements were detected by flame atomic absorption spectrometry (FAAS). The impact of several analytical parameters, such as pH, sample volume and coprecipitant amount as well as centrifugation rate and time was investigated to recover the examined metal ions. The influence of matrix ions was also tested, and no interferences were observed. The recovery values of the analyte ions were calculated and found to be in the range of 95-101%. The detection limits, corresponding to three times the standard deviation of the blank (N=10), were found to be in the range of 0.2-1.2 μg L(-1). The relative standard deviation (RSD) was calculated to evaluate the precision of the proposed method and was found to be ≤5.0%. The calculated preconcentration factor was 100. The proposed method was successfully applied to separate and preconcentrate trace amounts of ions in several water and food samples. To confirm the accuracy and validate the proposed method, certified reference materials were analyzed with satisfactory results.

  4. Purification of alkaline solutions and wastes from actinides and technetium by coprecipitation with some carriers using the method of appearing reagents: Final Report

    SciTech Connect

    Peretrukhin, V.F.; Silin, V.I.; Kareta, A.V.; Gelis, A.V.; Shilov, V.P.; German, K.E.; Firsova, E.V.; Maslennikov, A.G.; Trushina, V.E.

    1998-09-01

    The coprecipitation of transuranium elements (TRU) and technetium from alkaline solutions and from simulants of Hanford Site tank wastes has been studied in reducing and oxidizing conditions on uranium(IV,VI) hydroxocompounds, tetraalkylammonium perrhenate and perchlorate, and on hydroxides of Fe(III), Co(III), Mn(II), and Cr(III) using the method of appearing reagents (MAR). Coprecipitations in alkaline solution have been shown to give high decontamination factors (DF) at low content of carrier and in the presence of high salt concentrations. Uranium(IV) hydroxide in concentrations higher than 3 {times} 10{sup {minus}3} M coprecipitates Pu and Cm in any oxidation state from 0.2 to 4 M NaOH with DFs of 110 to 1000 and Np and Tc with DFs of 51 to 176. Technetium (VII) coprecipitates with (5 to 8) {times} 10{sup {minus}4} M tetrabutylammonium (TBA) perrhenate in 0.01 to 0.02 M TBA hydroxide from 0.5 to 1.5 M NaOH to give DFs of 150 to 200. Coprecipitations of Np and Pu with Co(OH){sub 3}, Fe(OH){sub 3}, Cr(OH){sub 3}, and Mn(OH){sub 2} obtained by the MAR from precursors in the range from pH 10.5 to 0.4 M NaOH give DFs from 80 to 400.

  5. Anaerobic microbial remobilization of coprecipitated metals

    DOEpatents

    Francis, Arokiasamy J.; Dodge, Cleveland J.

    1994-10-11

    A process is provided for solubilizing coprecipitated metals. Metals in wastestreams are concentrated by treatment with an iron oxide coprecipitating agent. The coprecipitated metals are solubilized by contacting the coprecipitate with a bacterial culture of a Clostridium species ATCC 53464. The remobilized metals can then be recovered and recycled.

  6. Anaerobic microbial remobilization of coprecipitated metals

    DOEpatents

    Francis, A.J.; Dodge, C.J.

    1994-10-11

    A process is provided for solubilizing coprecipitated metals. Metals in waste streams are concentrated by treatment with an iron oxide coprecipitating agent. The coprecipitated metals are solubilized by contacting the coprecipitate with a bacterial culture of a Clostridium species ATCC 53464. The remobilized metals can then be recovered and recycled. 4 figs.

  7. Element free Galerkin formulation of composite beam with longitudinal slip

    SciTech Connect

    Ahmad, Dzulkarnain; Mokhtaram, Mokhtazul Haizad; Badli, Mohd Iqbal; Yassin, Airil Y. Mohd

    2015-05-15

    Behaviour between two materials in composite beam is assumed partially interact when longitudinal slip at its interfacial surfaces is considered. Commonly analysed by the mesh-based formulation, this study used meshless formulation known as Element Free Galerkin (EFG) method in the beam partial interaction analysis, numerically. As meshless formulation implies that the problem domain is discretised only by nodes, the EFG method is based on Moving Least Square (MLS) approach for shape functions formulation with its weak form is developed using variational method. The essential boundary conditions are enforced by Langrange multipliers. The proposed EFG formulation gives comparable results, after been verified by analytical solution, thus signify its application in partial interaction problems. Based on numerical test results, the Cubic Spline and Quartic Spline weight functions yield better accuracy for the EFG formulation, compares to other proposed weight functions.

  8. Hexaferrite particles by coprecipitation and lyophilization

    NASA Astrophysics Data System (ADS)

    Calleja, A.; Tijero, E.; Martínez, B.; Piñol, S.; Sandiumenge, F.; Obradors, X.

    1999-05-01

    Fine strontium hexaferrite particles were prepared by lyophilization (known as freeze-drying) and coprecipitation of nitrates and chloride salts, respectively. The resulting powders were calcined at different temperatures between 700°C and 1100°C. As concluded from the measured hysteresis loops at 300 K, the freeze-dried hexaferrite showed good magnetic characteristics, the coercivity being as high as 5690 Oe. However, coprecipitated hexaferrite displayed poor coercivity values, around 1300 Oe at best.

  9. An interpolating boundary element-free method (IBEFM) for elasticity problems

    NASA Astrophysics Data System (ADS)

    Ren, Hongping; Cheng, Yumin; Zhang, Wu

    2010-04-01

    The paper begins by discussing the interpolating moving least-squares (IMLS) method. Then the formulae of the IMLS method obtained by Lancaster are revised. On the basis of the boundary element-free method (BEFM), combining the boundary integral equation method with the IMLS method improved in this paper, the interpolating boundary element-free method (IBEFM) for two-dimensional elasticity problems is presented, and the corresponding formulae of the IBEFM for two-dimensional elasticity problems are obtained. In the IMLS method in this paper, the shape function satisfies the property of Kronecker δ function, and then in the IBEFM the boundary conditions can be applied directly and easily. The IBEFM is a direct meshless boundary integral equation method in which the basic unknown quantity is the real solution to the nodal variables. Thus it gives a greater computational precision. Numerical examples are presented to demonstrate the method.

  10. Coprecipitation of Arsenate and Arsenite with Green Rust Minerals

    EPA Science Inventory

    The objectives of this experiment were to evaluate the extent and nature of arsenic co-precipitation with green rusts and to examine the influence of arsenic incorporation on the mineralogy of formed solid phases. Stoichiometric green rusts were obtained by coprecipitation of fe...

  11. GENERAL: An improved boundary element-free method (IBEFM) for two-dimensional potential problems

    NASA Astrophysics Data System (ADS)

    Ren, Hong-Ping; Cheng, Yu-Min; Zhang, Wu

    2009-10-01

    The interpolating moving least-squares (IMLS) method is discussed first in this paper. And the formulae of the IMLS method obtained by Lancaster are revised. Then on the basis of the boundary element-free method (BEFM), combining the boundary integral equation (BIE) method with the IMLS method, the improved boundary element-free method (IBEFM) for two-dimensional potential problems is presented, and the corresponding formulae of the IBEFM are obtained. In the BEFM, boundary conditions are applied directly, but the shape function in the MLS does not satisfy the property of the Kronecker δ function. This is a problem of the BEFM, and must be solved theoretically. In the IMLS method, when the shape function satisfies the property of the Kronecker δ function, then the boundary conditions, in the meshless method based on the IMLS method, can be applied directly. Then the IBEFM, based on the IMLS method, is a direct meshless boundary integral equation method in which the basic unknown quantity is the real solution of the nodal variables, and the boundary conditions can be applied directly and easily, thus it gives a greater computational precision. Some numerical examples are presented to demonstrate the method.

  12. Investigation on the co-precipitation of transuranium elements from alkaline solutions by the method of appearing reagents

    SciTech Connect

    Krot, N.; Shilov, V.; Bessonov, A.; Budantseva, N.; Charushnikova, I.; Perminov, V.; Astafurova, L.

    1996-06-06

    Highly alkaline radioactive waste solutions originating from production of plutonium for military purposes are stored in underground tanks at the U.S. Department of Energy Hanford Site. The purification of alkaline solutions from neptunium and plutonium is important in the treatment and disposal of these wastes. This report describes scoping tests with sodium hydroxide solutions, where precipitation techniques were investigated to perform the separation. Hydroxides of iron (III), manganese (II), cobalt (II, III), and chromium (III); manganese (IV) oxide, and sodium uranate were investigated as carriers. The report describes the optimum conditions that were identified to precipitate these carriers homogeneously throughout the solution by reductive, hydrolytic, or catalytic decomposition of alkali-soluble precursor compounds by a technique called the Method of Appearing Reagents. The coprecipitation of pentavalent and hexavalent neptunium and plutonium was investigated for the candidate agents under optimum conditions and is described in this report along with the following results. Plutonium coprecipitated well with all tested materials except manganese (IV) oxide. Neptunium only coprecipitated well with uranate. The report presents a hypothesis to explain these behaviors. Further tests with more complex solution matrices must be performed.

  13. Association of organic matter and ferrihydrite: adsorption versus coprecipitation

    NASA Astrophysics Data System (ADS)

    Eusterhues, K.; Rennert, T.; Knicker, H.; Totsche, K. U.

    2009-04-01

    Ferrihydrite (Fh) - even if present at low concentrations - may control the available surface area and therefore, the behaviour of nutrients and pollutants in soils. Its precipitation often takes place in the presence of dissolved organic matter (OM). This involves processes such as adsorption, but also coprecipitation, flocculation/coagulation and poisoning of crystal growth. In this study, we compare coprecipitation of organic matter and ferrihydrite with pure adsorption of OM on ferrihydrite. We therefore prepared an adsorption series and a coprecipitation series using (i) water extractable organic matter from a forest topsoil and (ii) sulfite extractable lignin from paper. Products were investigated by N2-adsorption, XRD and FTIR. In coprecipitation experiments with both types of OM we observed a strong interference of the organic molecules with crystal growth leading to smaller Fh crystals, increased lattice spacings and a lower crystallinity. The highest achieved C loadings were found at approximately 200 mg C per g Fh for the adsorption and coprecipitation of the soil extract as well as for the adsorption of lignin. Coprecipitation of lignin, in contrast, resulted in a much higher maximum loading of 360 mg C per g Fh. The FTIR spectrum of the unreacted soil extract is mainly characterized by carboxyl C and polysaccharide C, with a smaller contribution of phenolic C. Spectra of the adsorbed or coprecipitated soil extract reveal weaker bands and lowered wave numbers indicating removal from solution followed by the formation of chemical bonds between the organic species and Fh by inner-sphere surface complexes. The FTIR spectrum of the lignin material shows a strong contribution of carboxyl C, polysaccharide C, and several aromatic C species. Again, all of these C species seem to form surface complexes after reaction with Fh in adsorption and coprecipitation experiments. Interestingly, at low initial C concentrations in all experiments the sorption of carboxyl

  14. Free vibration analysis of functionally graded plates using the element-free kp-Ritz method

    NASA Astrophysics Data System (ADS)

    Zhao, X.; Lee, Y. Y.; Liew, K. M.

    2009-01-01

    A free vibration analysis of metal and ceramic functionally graded plates that uses the element-free kp-Ritz method is presented. The material properties of the plates are assumed to vary continuously through their thickness according to a power-law distribution of the volume fractions of the plate constituents. The first-order shear deformation plate theory is employed to account for the transverse shear strain and rotary inertia, and mesh-free kernel particle functions are used to approximate the two-dimensional displacement fields. The eigen-equation is obtained by applying the Ritz procedure to the energy functional of the system. Convergence studies are performed to examine the stability of the proposed method, and comparisons of the solutions derived with those reported in the literature are provided to verify its accuracy. Four types of functionally graded rectangular and skew plates—Al/Al 2O 3, Al/ZrO 2, Ti-6Al-4V/Aluminum oxide, and SUS304/Si 3N 4—are included in the study, and the effects of the volume fraction, boundary conditions, and length-to-thickness ratio on their frequency characteristics are discussed in detail.

  15. Coprecipitated, copper-based, alumina-stabilized materials for carbon dioxide capture by chemical looping combustion.

    PubMed

    Imtiaz, Qasim; Kierzkowska, Agnieszka Marta; Müller, Christoph Rüdiger

    2012-08-01

    Chemical looping combustion (CLC) has emerged as a carbon dioxide capture and storage (CCS) process to produce a pure stream of CO(2) at very low costs when compared with alternative CCS technologies, such as scrubbing with amines. From a thermodynamic point of view, copper oxide is arguably the most promising candidate for the oxygen carrier owing to its exothermic reduction and oxidation reactions and high oxygen-carrying capacity. However, the low melting point of pure copper of only 1085 °C has so far prohibited the synthesis of copper-rich oxygen carriers. This paper is concerned with the development of copper-based and Al(2)O(3)-stabilized oxygen carriers that contain a high mass fraction of CuO, namely, 82.4 wt %. The oxygen carriers were synthesized by using a coprecipitation technique. The synthesized oxygen carriers were characterized in detail with regards to their morphological properties, chemical composition, and surface topography. It was found that both the precipitating agent and the pH at which the precipitation was performed strongly influenced the structure and chemical composition of the oxygen carriers. In addition, XRD analysis confirmed that, for the majority of the precipitation conditions investigated, CuO reacted with Al(2)O(3) to form fully reducible CuAl(2)O(4). The redox characteristics of the synthesized materials were evaluated at 800 °C by using methane as the fuel and air for reoxidation. It was found that the oxygen-carrying capacity of the synthesized oxygen carriers was strongly influenced by both the precipitating agent and the pH at which the precipitation was performed; however, all oxygen carriers tested showed a stable cyclic oxygen-carrying capacity. The oxygen carriers synthesized at pH 5.5 using NaOH or Na(2)CO(3) as the precipitating agents were the best oxygen carriers synthesized owing to their high and stable oxygen transfer and uncoupling capacities. The excellent redox characteristics of the best oxygen carrier

  16. Synthetic coprecipitates of exopolysaccharides and ferrihydrite. Part I: Characterization

    NASA Astrophysics Data System (ADS)

    Mikutta, Christian; Mikutta, Robert; Bonneville, Steeve; Wagner, Friedrich; Voegelin, Andreas; Christl, Iso; Kretzschmar, Ruben

    2008-02-01

    Iron(III) (hydr)oxides formed at extracellular biosurfaces or in the presence of exopolymeric substances of microbes and plants may significantly differ in their structural and physical properties from their inorganic counterparts. We synthesized ferrihydrite (Fh) in solutions containing acid polysaccharides [polygalacturonic acid (PGA), alginate, xanthan] and compared its properties with that of an abiotic reference by means of X-ray diffraction, transmission electron microscopy, gas adsorption (N 2, CO 2), X-ray absorption spectroscopy, 57Fe Mössbauer spectroscopy, and electrophoretic mobility measurements. The coprecipitates formed contained up to 37 wt% polymer. Two-line Fh was the dominant mineral phase in all precipitates. The efficacy of polymers to precipitate Fh at neutral pH was higher for polymers with more carboxyl C (PGA ˜ alginate > xanthan). Pure Fh had a specific surface area of 300 m 2/g; coprecipitation of Fh with polymers reduced the detectable mineral surface area by up to 87%. Likewise, mineral micro- (<2 nm) and mesoporosity (2-10 nm) decreased by up to 85% with respect to pure Fh, indicative of a strong aggregation of Fh particles by polymers in freeze-dried state. C-1s STXM images showed the embedding of Fh particles in polymer matrices on the micrometer scale. Iron EXAFS spectroscopy revealed no significant changes in the local coordination of Fe(III) between pure Fh and Fh contained in PGA coprecipitates. 57Fe Mössbauer spectra of coprecipitates confirmed Fh as dominant mineral phase with a slightly reduced particle size and crystallinity of coprecipitate-Fh compared to pure Fh and/or a limited magnetic super-exchange between Fh particles in the coprecipitates due to magnetic dilution by the polysaccharides. The pH iep of pure Fh in 0.01 M NaClO 4 was 7.1. In contrast, coprecipitates of PGA and alginate had a pH iep < 2. Considering the differences in specific surface area, porosity, and net charge between the coprecipitates and pure Fh

  17. GPU-accelerated Modeling and Element-free Reverse-time Migration with Gauss Points Partition

    NASA Astrophysics Data System (ADS)

    Zhen, Z.; Jia, X.

    2014-12-01

    Element-free method (EFM) has been applied to seismic modeling and migration. Compared with finite element method (FEM) and finite difference method (FDM), it is much cheaper and more flexible because only the information of the nodes and the boundary of the study area are required in computation. In the EFM, the number of Gauss points should be consistent with the number of model nodes; otherwise the accuracy of the intermediate coefficient matrices would be harmed. Thus when we increase the nodes of velocity model in order to obtain higher resolution, we find that the size of the computer's memory will be a bottleneck. The original EFM can deal with at most 81×81 nodes in the case of 2G memory, as tested by Jia and Hu (2006). In order to solve the problem of storage and computation efficiency, we propose a concept of Gauss points partition (GPP), and utilize the GPUs to improve the computation efficiency. Considering the characteristics of the Gaussian points, the GPP method doesn't influence the propagation of seismic wave in the velocity model. To overcome the time-consuming computation of the stiffness matrix (K) and the mass matrix (M), we also use the GPUs in our computation program. We employ the compressed sparse row (CSR) format to compress the intermediate sparse matrices and try to simplify the operations by solving the linear equations with the CULA Sparse's Conjugate Gradient (CG) solver instead of the linear sparse solver 'PARDISO'. It is observed that our strategy can significantly reduce the computational time of K and Mcompared with the algorithm based on CPU. The model tested is Marmousi model. The length of the model is 7425m and the depth is 2990m. We discretize the model with 595x298 nodes, 300x300 Gauss cells and 3x3 Gauss points in each cell. In contrast to the computational time of the conventional EFM, the GPUs-GPP approach can substantially improve the efficiency. The speedup ratio of time consumption of computing K, M is 120 and the

  18. Incorporation of Chromate into Calcium Carbonate Structure during Coprecipitation

    SciTech Connect

    Hua, Bin; Deng, Baolin; Thornton, Edward C.; Yang, J.; Amonette, James E.

    2006-09-08

    To assess treatment technologies and establish regulatory framework for chromate-contaminated site remediation, it is imperative to know the exact chromium speciation in soil matrices. In an earlier study, Thornton and Amonette (1999) reported that some chromate in the bulk particles was not accessible to gaseous reductants or solution-phase extractants, based on XANES studies. We hypothesized that part of this non-extractable chromate may reside in the structure of minerals such as calcium carbonate. To test this hypothesis, a number of calcium carbonate precipitates were prepared in the presence of various concentrations of chromate during the precipitation, which could coprecipitate chromate, or by adding chromate after the precipitation was completed. Hydrochloric acid was used to dissolve calcium carbonate and therefore extract the coprecipitated and surface attached chromate. The results showed that the coprecipitated chromate was non-extractable by hot alkaline solution or phosphate buffer, but could be solubilized by HCl in proportional to the amount of calcium carbonate dissolved. The X-ray diffraction experiments revealed that the coprecipitation of chromate with calcium carbonate had an influence on its crystal structure: the higher the chromate concentration, the greater the ratio of vaterite to calcite.

  19. Ammonium sulfate co-precipitation of SSB and interacting proteins.

    PubMed

    Marceau, Aimee H

    2012-01-01

    Bacterial single-strand DNA-binding protein (SSB) interacts with many proteins involved in the diverse process of genome maintenance. The interactions are mediated by the essential and conserved amphipathic C-terminus (SSB-Ct). SSB plays a critical role in localizing and stimulating the activity of a wide variety of DNA-processing proteins. The interaction partners have been identified and studied using a variety of methods, one of which, ammonium sulfate co-precipitation, is described here.

  20. NMR spectroscopic study of organic phosphate esters coprecipitated with calcite

    NASA Astrophysics Data System (ADS)

    Phillips, Brian L.; Zhang, Zelong; Kubista, Laura; Frisia, Silvia; Borsato, Andrea

    2016-06-01

    Organic phosphorus incorporated in calcite during laboratory precipitation experiments and in natural cave deposits was investigated by solid-state NMR spectroscopy. For calcite precipitated in the presence of organic phosphoesters of varying size and functionality, solid-state 31P{1H} CP/MAS NMR shows that the phosphoesters were incorporated intact into the solid. Systematic changes in the 31P NMR chemical shift of the phosphate group were observed between the solid phosphoester and that incorporated in the solid precipitate, yielding 31P NMR chemical shifts of the coprecipitates in the range of +1.8 to -2.2 ppm. These chemical shifts are distinct from that of similarly prepared calcite coprecipitated with inorganic phosphate, 3.5 ppm. Only minor changes were noted in the phosphoester 31P chemical shift anisotropy (CSA) which suggests no significant change in the local structure of the phosphate group, which is dominated by C-O-P bonding. Close spatial proximity of the organic phosphate group to calcite structural components was revealed by 31P/13C rotational echo double resonance (REDOR) experiments for coprecipitates prepared with 13C-labeled carbonate. All coprecipitates showed significant 31P dephasing effects upon 13C-irradiation, signaling atomic-scale proximity to carbonate carbon. The dephasing rate for smaller organophosphate molecules is similar to that observed for inorganic phosphate, whereas much slower dephasing was observed for larger molecules having long and/or bulky side-chains. This result suggests that small organic molecules can be tightly enclosed within the calcite structure, whereas significant structural disruption required to accommodate the larger organic molecules leads to longer phosphate-carbonate distances. Comparison of 31P NMR spectroscopic data from the synthetic coprecipitates with those from calcite moonmilk speleothems indicates that phosphorus occurs mainly as inorganic orthophosphate in the natural deposits, although small

  1. Multi-Element Preconcentration/Separation of Some Metal Ions in Environmental Samples by Using Co-precipitation.

    PubMed

    Soylak, Mustafa; Aydin, Ayse; Kizil, Nebiye

    2016-01-01

    A preconcentration/separation system for cadmium(II), nickel(II), copper(II), lead(II), iron(II), cobalt(II), and manganese(II) ions has been established prior to their atomic absorption spectrometric determinations. The procedure is based on the co-precipitation of these ions by the aid of a praseodymium hydroxide (Pr(OH)3) precipitate. The precipitate was dissolved in 0.5 mL of concentrated HNO3, and made up to 10.0 mL with water. The analytes were determined by a flame atomic absorption spectrometer. The effects of analytical parameters including pH, amounts of praseodymium as carrier element, sample volume, etc. on the recoveries of heavy metals were investigated. The effects of matrix ions were also examined. The limits of detection for analyte ions were found in the range between 0.7-5.2 μg/L. The validation of this present procedure was verified by the analysis of certified reference materials, TMDA-54.4 (fortified water) and NIST 1570a (spinach leaves). The proposed co-precipitation procedure was applied for the determination of cadmium(II), nickel(II), copper(II), lead(II), iron(II), cobalt(II), and manganese(II) ions in various environmental water samples.

  2. Multi-Element Preconcentration/Separation of Some Metal Ions in Environmental Samples by Using Co-precipitation.

    PubMed

    Soylak, Mustafa; Aydin, Ayse; Kizil, Nebiye

    2016-01-01

    A preconcentration/separation system for cadmium(II), nickel(II), copper(II), lead(II), iron(II), cobalt(II), and manganese(II) ions has been established prior to their atomic absorption spectrometric determinations. The procedure is based on the co-precipitation of these ions by the aid of a praseodymium hydroxide (Pr(OH)3) precipitate. The precipitate was dissolved in 0.5 mL of concentrated HNO3, and made up to 10.0 mL with water. The analytes were determined by a flame atomic absorption spectrometer. The effects of analytical parameters including pH, amounts of praseodymium as carrier element, sample volume, etc. on the recoveries of heavy metals were investigated. The effects of matrix ions were also examined. The limits of detection for analyte ions were found in the range between 0.7-5.2 μg/L. The validation of this present procedure was verified by the analysis of certified reference materials, TMDA-54.4 (fortified water) and NIST 1570a (spinach leaves). The proposed co-precipitation procedure was applied for the determination of cadmium(II), nickel(II), copper(II), lead(II), iron(II), cobalt(II), and manganese(II) ions in various environmental water samples. PMID:27053469

  3. Enhanced gene transfection using calcium phosphate co-precipitates and low-intensity pulsed ultrasound.

    PubMed

    Hassan, Mariame A; Ahmed, Iman S; Campbell, Paul; Kondo, Takashi

    2012-11-20

    The capability to controllably disrupt the cell membrane by ultrasound (US), thus facilitating entry of exogenous species, has now reached a state of some maturity. However, a compelling question asks whether there is a residual role for US in enhancing transfection: that is, once the genetic material has been delivered to the cytosol, can US assist in its transport into the nucleus? The present experiment was designed with a view to addressing this question. As such, our experimental setup discriminates between: (i) the precursor cell membrane permealization step, and (ii) any subsequent intracellular trafficking into the nucleus. In this study, calcium phosphate co-precipitates (CaP) were used to internalize plasmid DNA encoding for luciferase (pDNA-Luc) (>90%) in HeLa cells. After 2h incubation with the CaP-pDNA-Luc, cells were washed and insonated for varying durations. The results showed that US can indeed enhance the intracellular trafficking of previously internalized genes when longer insonation periods are implemented, culminating with an increased probability for successful nuclear localization, as inferred from an enhanced luciferase expression. Moreover, the results suggest that the intracellular role of US might be mediated through a pathway that appears not to be limited to destabilizing the endosomal vesicles. The study thus provides new information regarding the intracellular effects of US, and in effect represents a new modality combining US and CaP carriers for improved efficiency in gene delivery.

  4. A comparative physicochemical, morphological and magnetic study of silane-functionalized superparamagnetic iron oxide nanoparticles prepared by alkaline coprecipitation.

    PubMed

    Mireles, Laura-Karina; Sacher, Edward; Yahia, L'Hocine; Laurent, Sophie; Stanicki, Dimitri

    2016-06-01

    The characterization of synthetic superparamagnetic iron oxide nanoparticle (SPION) surfaces prior to functionalization is an essential step in the prediction of their successful functionalization, and in uncovering issues that may influence their selection as magnetically targeted drug delivery vehicles (prodrugs). Here, three differently functionalized magnetite (Fe3O4) SPIONs are considered. All were identically prepared by the alkaline coprecipitation of Fe(2+) and Fe(3+) salts. We use X-ray photoelectron spectroscopy, electron microscopy, time-of-flight SIMS, FTIR spectroscopy and magnetic measurements to characterize their chemical, morphological and magnetic properties, in order to aid in determining how their surfaces differ from those prepared by Fe(CO)5 decomposition, which we have already studied, and in assessing their potential use as drug delivery carriers.

  5. Carrier rockets

    NASA Astrophysics Data System (ADS)

    Aleksandrov, V. A.; Vladimirov, V. V.; Dmitriev, R. D.; Osipov, S. O.

    This book takes into consideration domestic and foreign developments related to launch vehicles. General information concerning launch vehicle systems is presented, taking into account details of rocket structure, basic design considerations, and a number of specific Soviet and American launch vehicles. The basic theory of reaction propulsion is discussed, giving attention to physical foundations, the various types of forces acting on a rocket in flight, basic parameters characterizing rocket motion, the effectiveness of various approaches to obtain the desired velocity, and rocket propellants. Basic questions concerning the classification of launch vehicles are considered along with construction and design considerations, aspects of vehicle control, reliability, construction technology, and details of structural design. Attention is also given to details of rocket motor design, the basic systems of the carrier rocket, and questions of carrier rocket development.

  6. Determination of heavy metals at sub-ppm levels in seawater and dialysis solutions by FAAS after tetrakis(pyridine)-nickel(II)bis(thiocyanate) coprecipitation.

    PubMed

    Sahin, Uğur; Kartal, Senol; Ulgen, Ahmet

    2008-06-01

    A coprecipitation method has been developed for the determination of Cr(III), Mn(II), Fe(III), Co(II), Cu(II), Cd(II) and Pb(II) ions in aqueous samples by flame atomic absorption spectrometry (FAAS) with the combination of pyridine, nickel(II) as a carrier element and potassium thiocyanate as an auxiliary complexing agent. The obtained coprecipitates were dissolved with nitric acid and measured by FAAS. The coprecipitation conditions, such as the effect of the pH, amounts of nickel, pyridine and potassium thiocyanate, sample volume, and the standing time of the precipitate formation were examined in detail. It was found that the metal ions studied were quantitatively coprecipitated with tetrakis(pyridine)-nickel(II)bis(thiocyanate) precipitate (TP-Ni-BT) in the pH range of 9.0 - 10.5. The reliability of the results was evaluated by recovery tests, using synthetic seawater solutions spiked with the analyte metal ions. The obtained recoveries ranged from 96 to 101% for all of the metal ions investigated. The proposed method was validated by analyses of two certified reference materials (NIST SRM 2711 Montana soil and HPS Certified Waste Water Trace Metals Lot #D532205). It was also successfully applied to seawater and dialysis solution samples. The detection limits (n = 25, 3s) were in the range of 0.01-2.44 microg l(-1) for the studied elements and the relative standard deviations were < or =6%, which indicated that this method could fully satisfy the requirements for analysis of such samples as seawater and dialysis solution having high salt contents. PMID:18544864

  7. Co-precipitation of radium with barium and strontium sulfate and its impact on the fate of radium during treatment of produced water from unconventional gas extraction.

    PubMed

    Zhang, Tieyuan; Gregory, Kelvin; Hammack, Richard W; Vidic, Radisav D

    2014-04-15

    Radium occurs in flowback and produced waters from hydraulic fracturing for unconventional gas extraction along with high concentrations of barium and strontium and elevated salinity. Radium is often removed from this wastewater by co-precipitation with barium or other alkaline earth metals. The distribution equation for Ra in the precipitate is derived from the equilibrium of the lattice replacement reaction (inclusion) between the Ra(2+) ion and the carrier ions (e.g., Ba(2+) and Sr(2+)) in aqueous and solid phases and is often applied to describe the fate of radium in these systems. Although the theoretical distribution coefficient for Ra-SrSO4 (Kd = 237) is much larger than that for Ra-BaSO4 (Kd = 1.54), previous studies have focused on Ra-BaSO4 equilibrium. This study evaluates the equilibria and kinetics of co-precipitation reactions in Ra-Ba-SO4 and Ra-Sr-SO4 binary systems and the Ra-Ba-Sr-SO4 ternary system under varying ionic strength (IS) conditions that are representative of brines generated during unconventional gas extraction. Results show that radium removal generally follows the theoretical distribution law in binary systems and is enhanced in the Ra-Ba-SO4 system and restrained in the Ra-Sr-SO4 system by high IS. However, the experimental distribution coefficient (Kd') varies widely and cannot be accurately described by the distribution equation, which depends on IS, kinetics of carrier precipitation and does not account for radium removal by adsorption. Radium removal in the ternary system is controlled by the co-precipitation of Ra-Ba-SO4, which is attributed to the rapid BaSO4 nucleation rate and closer ionic radii of Ra(2+) with Ba(2+) than with Sr(2+). Carrier (i.e., barite) recycling during water treatment was shown to be effective in enhancing radium removal even after co-precipitation was completed. Calculations based on experimental results show that Ra levels in the precipitate generated in centralized waste treatment facilities far

  8. Co-precipitation of radium with barium and strontium sulfate and its impact on the fate of radium during treatment of produced water from unconventional gas extraction.

    PubMed

    Zhang, Tieyuan; Gregory, Kelvin; Hammack, Richard W; Vidic, Radisav D

    2014-04-15

    Radium occurs in flowback and produced waters from hydraulic fracturing for unconventional gas extraction along with high concentrations of barium and strontium and elevated salinity. Radium is often removed from this wastewater by co-precipitation with barium or other alkaline earth metals. The distribution equation for Ra in the precipitate is derived from the equilibrium of the lattice replacement reaction (inclusion) between the Ra(2+) ion and the carrier ions (e.g., Ba(2+) and Sr(2+)) in aqueous and solid phases and is often applied to describe the fate of radium in these systems. Although the theoretical distribution coefficient for Ra-SrSO4 (Kd = 237) is much larger than that for Ra-BaSO4 (Kd = 1.54), previous studies have focused on Ra-BaSO4 equilibrium. This study evaluates the equilibria and kinetics of co-precipitation reactions in Ra-Ba-SO4 and Ra-Sr-SO4 binary systems and the Ra-Ba-Sr-SO4 ternary system under varying ionic strength (IS) conditions that are representative of brines generated during unconventional gas extraction. Results show that radium removal generally follows the theoretical distribution law in binary systems and is enhanced in the Ra-Ba-SO4 system and restrained in the Ra-Sr-SO4 system by high IS. However, the experimental distribution coefficient (Kd') varies widely and cannot be accurately described by the distribution equation, which depends on IS, kinetics of carrier precipitation and does not account for radium removal by adsorption. Radium removal in the ternary system is controlled by the co-precipitation of Ra-Ba-SO4, which is attributed to the rapid BaSO4 nucleation rate and closer ionic radii of Ra(2+) with Ba(2+) than with Sr(2+). Carrier (i.e., barite) recycling during water treatment was shown to be effective in enhancing radium removal even after co-precipitation was completed. Calculations based on experimental results show that Ra levels in the precipitate generated in centralized waste treatment facilities far

  9. Uranium Isotope Fractionation During Coprecipitation with Aragonite and Calcite

    NASA Astrophysics Data System (ADS)

    Chen, X.; Romaniello, S. J.; Herrmann, A. D.; Wasylenki, L. E.; Anbar, A. D.

    2014-12-01

    Natural variations in the 238U/235U ratio of marine carbonates may provide a useful way of constraining past variations in ocean redox conditions. However, before applying this novel redox proxy, it is essential to explore possible isotopic fractionation during U coprecipitation with aragonite and calcite. We investigated these effects in laboratory experiments. Aragonite and calcite coprecipitation experiments were conducted at pH 8.5±0.1 using a constant addition method [1]. More than 90% of the U was incorporated into the solid phase at the end of each experiment. Samples were purified using UTEVA chemistry and δ238/235U was measured using 233U-236U double-spike MC-ICP-MS with a precision of ±0.10‰ [2]. The aragonite experiment demonstrated a 238U/235U Rayleigh fractionation factor of α=1.00008±0.00002 with the 238U preferentially incorporated. In contrast, the calcite experiment demonstrated no resolvable U isotope fractionation (α=1.00001±0.00003). To determine if U isotopes are affected during the early diagenetic conversion of aragonite to calcite, natural carbonate samples were collected along an aragonite-calcite transition across a single coral head in the Key Largo limestone, and characterized for U concentration and δ238/235U [3]. We found that the mean δ238/235U in aragonite (-0.33±0.07‰ 2se) was slightly heavier than that in calcite (-0.37±0.02‰ 2se). Further work is needed to address the mechanisms leading to differential isotopic fractionation of U(VI) during incorporation into aragonite and calcite. Possible drivers include differences in coordination in the crystal structure or equilibrium isotopic fractionation between various aqueous U(VI) species prior to incorporation. [1] Reeder et al. (2001) GCA 65, 3491-3503. [2] Weyer et al., (2008) GCA 72, 345-359. [3] Gill et al., (2008) GCA 72, 4699-4722.

  10. Technetium (VII) Co-precipitation with Framework Aluminosilicates

    SciTech Connect

    Harsh, James B.; Dickson, Johnbull Otah; Pierce, Eric M.; Bargar, John

    2015-07-13

    Technetium-99 (99Tc), a long-lived radionuclide, is one of the most widespread contaminants within the Hanford subsurface. At some depths, it is only extractable with strong acids, suggesting incorporation into a solid phase. We hypothesized that Tc may have coprecipitated with feldspathoid aluminosilicates under waste tanks that had leaked caustic solutions into the vadose zone. Our objectives were to determine if Tc could be incorporated into the feldspathoids cancrinite and sodalite and under what conditions coprecipitation could occur. Our hypothesis was that sodalite was more likely to incorporate and retain Tc. Our approach was to use known methods of feldspathoid formation in solutions resembling those in Hanford waste tanks contacting sediments in terms of major ion (Na, NO3, OH, Al(OH)4, and Si(OH)4 concentrations. In some cases, Al and Si were supplied from zeolite. We used perrhenate (ReO4) as a surrogate for pertechnetate (TcO4) to avoid the radioactivity. The major findings of this study were 1) ReO4 could be incorporated into either sodalite or cancrinite but the concentration in the solid was < 1% of the competing ion Cl, NO3, or NO2. 2) The small amount of ReO4 incorporated was not exchangeable with NO3 or NO2. 3) In sodalite, NO3 was highly preferred over ReO4 but significant Re-sodalite was formed when the mole fraction in solution (Re/Re+N) exceeded 0.8. 4) A nonlinear relation between the unit cell parameter and amount of Re incorporated suggested that a separate Re-sodalite phase was formed rather than a solid solution. 5) We determined that sodalite preference for sodalite in the presence of different anions increased with the ionic size of the competing anion: Cl < CO3 < NO3 < SO4 < MnO4 < WO4 and significant incorporation did not occur unless the difference in anion radii was less than 12%. 6) Re(VII) was not significantly reduced to Re(IV) under the conditions of this experiment and Re appeared to be a good surrogate for Tc under oxidizing

  11. Properties of Fe-organic matter associations via coprecipitation versus adsorption.

    PubMed

    Chen, Chunmei; Dynes, James J; Wang, Jian; Sparks, Donald L

    2014-12-01

    The association of organic matter (OM) with minerals is recognized as the most important stabilization mechanism for soil organic matter. This study compared the properties of Fe-OM complexes formed from adsorption (reaction of OM to postsynthesis ferrihydrite) versus coprecipitation (formation of Fe solids in the presence of OM). Coprecipitates and adsorption complexes were synthesized using dissolved organic matter (DOM) extracts from a forest little layer at varying molar C/Fe ratios of 0.3-25.0. Sample properties were studied by N2 gas adsorption, XRD, FTIR, Fe EXAFS, and STXM-NEXAFS techniques. Coprecipitation resulted in much higher maximum C contents (∼130 mg g(-1) C difference) in the solid products than adsorption, which may be related to the formation of precipitated insoluble Fe(III)-organic complexes at high C/Fe ratios in the coprecipitates as revealed by Fe EXAFS analysis. Coprecipitation led to a complete blockage of mineral surface sites and pores with ≥177 mg g(-1) C and molar C/Fe ratios ≥2.8 in the solid products. FTIR and STXM-NEXAFS showed that the coprecipitated OM was similar in composition to the adsorbed OM. An enrichment of aromatic C was observed at low C/Fe ratios. Association of carboxyl functional groups with Fe was shown with FTIR and STXM-NEXAFS analysis. STXM-NEXAFS analysis showed a continuous C distribution on minerals. Desorption of the coprecipitated OM was less than that of the adsorbed OM at comparable C/Fe ratios. These results are helpful to understand C and Fe cycling in the natural environments with periodically fluctuating redox conditions, where coprecipitation can occur.

  12. Effects of natural organic matter on the coprecipitation of arsenic with iron.

    PubMed

    Kim, Eun Jung; Hwang, Bo-Ram; Baek, Kitae

    2015-12-01

    Natural organic matter (NOM) can affect arsenic speciation and mobility in the environment. In this study, the effects of NOM on the coprecipitation of arsenic with iron were investigated in order to better understand the fate and transport of arsenic in natural environments. The coprecipitation of arsenic with iron was studied in the presence and absence of NOM under various arsenic-to-iron molar ratios (As/Fe) and pH conditions. The addition of humic acid (HA) hindered the As-Fe coprecipitation under high pH and high As/Fe conditions by forming a soluble As-Fe-HA complex. The X-ray diffraction and Fourier transform infrared studies showed that the As-Fe-coprecipitated solid phase was highly affected by pH and As/Fe. The arsenic was coprecipitated with iron as an amorphous ferric arsenate phase at a low pH level or high As/Fe conditions, while the formation of ferrihydrite phase and the arsenic incorporation to the ferrihydrite by adsorption was predominant at high pH levels or low As/Fe conditions. The HA affected the As-Fe-coprecipitated solid phase depending on the As/Fe molar ratio under neutral and alkaline conditions.

  13. Coprecipitation and isotopic fractionation of boron in modern biogenic carbonates

    SciTech Connect

    Vengosh, A. Hebrew Univ., Jerusalem ); Chivas, A.R.; McCulloch, M.T. ); Kolodny, Y.; Starinsky, A. )

    1991-10-01

    The abundances and isotopic composition of boron in modern, biogenic calcareous skeletons from the Gulf of Elat, Israel, the Great Barrier Reef, Australia, and in deep-sea sediments have been examined by negative thermal-ionization mass spectrometry. The selected species (Foraminifera, Pteropoda, corals, Gastropoda, and Pelecypoda) yield large variations in boron concentration that range from 1 ppm in gastropod shells to 80 ppm in corals. The variations of {delta}{sup 11}B may be controlled by isotopic exchange of boron species in which {sup 10}B is preferentially partitioned into the tetrahedral species, and coprecipitation of different proportions of trigonal and tetrahedral species in the calcium carbonates. The B content and {delta}{sup 11}B values of deep-sea sediments, Foraminifera tests, and corals are used to estimate the global oceanic sink of elemental boron by calcium carbonate deposition. As a result of enrichment of B in corals, a substantially higher biogenic sink of 6.4 {plus minus} 0.9 {times} 10{sup 10} g/yr is calculated for carbonates. This is only slightly lower than the sink for desorbable B in marine sediments (10 {times} 10{sup 10} g/yr) and approximately half that of altered oceanic crust (14 {times} 10{sup 10} g/yr). Thus, carbonates are an important sink for B in the oceans being {approximately}20% of the total sinks. The preferential incorporation of {sup 10}B into calcium carbonate results in oceanic {sup 11}B-enrichment, estimated as 1.2 {plus minus} 0.3 {times} 10{sup 12} per mil {center dot} g/yr. The boron-isotope composition of authigenic, well-preserved carbonate skeletons may provide a useful tool to record secular boron-isotope variations in seawater at various times in the geological record.

  14. What Is Carrier Screening?

    MedlinePlus

    ... you want to learn. Search form Search Carrier screening You are here Home Testing & Services Testing for ... help you make the decision. What Is Carrier Screening? Carrier screening checks if a person is a " ...

  15. Synthetic coprecipitates of exopolysaccharides and ferrihydrite. Part II: Siderophore-promoted dissolution

    NASA Astrophysics Data System (ADS)

    Mikutta, Christian; Kretzschmar, Ruben

    2008-02-01

    Ferrihydrite (Fh) coprecipitated with exopolymers of plants and microbes may differ in its geochemical reactivity from its abiotic counterpart. We synthesized Fh in the presence and absence of acid polysaccharides (polygalacturonic acid (PGA), alginate, xanthan) and characterized the physical and structural properties of the precipitates formed [Mikutta C., Mikutta R., Bonneville S., Wagner F., Voegelin A., Christl I. and Kretzschmar R. (2008) Synthetic coprecipitates of exopolysaccharides and ferrihydrite. Part I: Characterization. Geochim. Cosmochim. Acta]. In this paper, we focus on the reactivity of PGA and alginate coprecipitates and pure Fh, and studied their interaction with the microbial siderophore desferrioxamine B (DFOB) in the presence and absence of low molecular weight organic (LMWO) acid anions (malate, citrate). Batch adsorption and dissolution experiments were performed in the dark at pH 7 in 10 mM NaClO 4 background electrolyte. In the dissolution experiments, different modes of ligand addition were applied (single, simultaneous, stepwise). With an estimated Langmuir sorption maximum of 15 mmol/mol Fe, a PGA coprecipitate with 11% C org sorbed about four times as much DFOB as pure Fh, and the amount of DFOB sorbed was ˜4-fold larger than estimated from the sum of DFOB sorption to pure Fh and PGA alone. The apparent initial dissolution rates, Rapp-initial, and pseudo-first order rate coefficients, k, of the coprecipitates exceeded those of pure Fh by up to two orders of magnitude. Citrate and malate exerted a strong synergistic effect on the DFOB-promoted dissolution of pure Fh, whereas synergistic effects of both anions were absent or negligible for the coprecipitates. Rapp-initial of the citrate and DFOB-promoted dissolution of PGA coprecipitates increased with increasing molar C/Fe ratio of the coprecipitates, independent of the charge of the LMWO ligand. Our results indicate that polyuronates stabilize Fh particles sterically and /or

  16. Uranium isotope fractionation during coprecipitation with aragonite and calcite

    NASA Astrophysics Data System (ADS)

    Chen, Xinming; Romaniello, Stephen J.; Herrmann, Achim D.; Wasylenki, Laura E.; Anbar, Ariel D.

    2016-09-01

    Natural variations in 238U/235U of marine calcium carbonates might provide a useful way of constraining redox conditions of ancient environments. In order to evaluate the reliability of this proxy, we conducted aragonite and calcite coprecipitation experiments at pH ∼7.5 and ∼8.5 to study possible U isotope fractionation during incorporation into these minerals. Small but significant U isotope fractionation was observed in aragonite experiments at pH ∼8.5, with heavier U isotopes preferentially enriched in the solid phase. 238U/235U of dissolved U in these experiments can be fit by Rayleigh fractionation curves with fractionation factors of 1.00007 + 0.00002/-0.00003, 1.00005 ± 0.00001, and 1.00003 ± 0.00001. In contrast, no resolvable U isotope fractionation was observed in an aragonite experiment at pH ∼7.5 or in calcite experiments at either pH. Equilibrium isotope fractionation among different aqueous U species is the most likely explanation for these findings. Certain charged U species are preferentially incorporated into calcium carbonate relative to the uncharged U species Ca2UO2(CO3)3(aq), which we hypothesize has a lighter equilibrium U isotope composition than most of the charged species. According to this hypothesis, the magnitude of U isotope fractionation should scale with the fraction of dissolved U that is present as Ca2UO2(CO3)3(aq). This expectation is confirmed by equilibrium speciation modeling of our experiments. Theoretical calculation of the U isotope fractionation factors between different U species could further test this hypothesis and our proposed fractionation mechanism. These findings suggest that U isotope variations in ancient carbonates could be controlled by changes in the aqueous speciation of seawater U, particularly changes in seawater pH, PCO2 , Ca2+, or Mg2+ concentrations. In general, these effects are likely to be small (<0.13‰), but are nevertheless potentially significant because of the small natural range of

  17. Effects of natural organic matter on calcium and phosphorus co-precipitation.

    PubMed

    Sindelar, Hugo R; Brown, Mark T; Boyer, Treavor H

    2015-11-01

    Phosphorus (P), calcium (Ca) and natural organic matter (NOM) naturally occur in all aquatic ecosystems. However, excessive P loads can cause eutrophic or hyper-eutrophic conditions in these waters. As a result, P regulation is important for these impaired aquatic systems, and Ca-P co-precipitation is a vital mechanism of natural P removal in many alkaline systems, such as the Florida Everglades. The interaction of P, Ca, and NOM is also an important factor in lime softening and corrosion control, both critical processes of drinking water treatment. Determining the role of NOM in Ca-P co-precipitation is important for identifying mechanisms that may limit P removal in both natural and engineered systems. The main goal of this research is to assess the role of NOM in inhibiting Ca and P co-precipitation by: (1) measuring how Ca, NOM, and P concentrations affect NOM's potential inhibition of co-precipitation; (2) determining the effect of pH; and (3) evaluating the precipitated solids. Results showed that Ca-P co-precipitation occurs at pH 9.5 in the presence of high natural organic matter (NOM) (≈30 mg L(-1)). The supersaturation of calcite overcomes the inhibitory effect of NOM seen at lower pH values. Higher initial P concentrations lead to both higher P precipitation rates and densities of P on the calcite surface. The maximum surface density of co-precipitated P on the precipitated calcite surface increases with increasing NOM levels, suggesting that NOM does prevent the co-precipitation of Ca and P.

  18. Investigation on the coprecipitation of transuranium elements from alkaline solutions by the method of appearing reagents. Study of the effects of waste components on decontamination from Np(IV) and Pu(IV)

    SciTech Connect

    Bessonov, A.A.; Budantseva, N.A.; Gelis, A.V.; Nikonov, M.V.; Shilov, V.P.

    1997-09-01

    The third stage of the study on the homogeneous coprecipitation of neptunium and plutonium from alkaline high-level radioactive waste solutions by the Method of Appearing Reagents has been completed. Alkaline radioactive wastes exist at the U.S. Department of Energy Hanford Site. The recent studies investigated the effects of neptunium chemical reductants, plutonium(IV) concentration, and the presence of bulk tank waste solution components on the decontamination from tetravalent neptunium and plutonium achieved by homogeneous coprecipitation. Data on neptunium reduction to its tetravalent state in alkaline solution of different NaOH concentrations are given. Eleven reductants were tested to find those most suited to remove neptunium, through chemical reduction, from alkaline solution by homogeneous coprecipitation. Hydrazine, VOSO{sub 4}, and Na{sub 2}S{sub 2}O{sub 4} were found to be the most effective reductants. The rates of reduction with these reductants were comparable with the kinetics of carrier formation. Solution decontamination factors of about 400 were attained for 10{sup -6}M neptunium. Coprecipitation of plutonium(IV) with carriers obtained as products of thermal hydrolysis, redox transformations, and catalytic decomposition of [Co(NH{sub 3}){sub 6}]{sup 3+}, [Fe(CN){sub 5}NO]{sup 2-}, Cr(NO{sub 3}){sub 3}, KMnO{sub 4}, and Li{sub 4}UO{sub 2}(O{sub 2}){sub 3} was studied and results are described. Under optimum conditions, a 100-fold decrease of plutonium concentration was possible with each of these reagents.

  19. Molecular Structures of Al/Si and Fe/Si Coprecipitates and the Implication for Selenite Removal

    NASA Astrophysics Data System (ADS)

    Chan, Ya-Ting; Kuan, Wen-Hui; Tzou, Yu-Min; Chen, Tsan-Yao; Liu, Yu-Ting; Wang, Ming-Kuang; Teah, Heng-Yi

    2016-04-01

    Aluminum and iron oxides have been often used in the coagulation processes during water purification due to their unique surface properties toward anions. In the presence of silica, the coprecipitation of Al/Si or Fe/Si might decrease the efficiency of wastewater purification and reuse. In this study, surface properties and molecular structures of Al/Si and Fe/Si coprecipitates were characterized using spectroscopic techniques. Also, the selenite removal efficiency of Al/Si and Fe/Si coprecipitates in relation to their surface and structural properties was investigated. While dissolved silicate increased with increasing pH from Fe/Si coprecipitates, less than 7% of silicate was discernible from Al/Si samples over the range from acidic to alkaline conditions. Our spectroscopic results showed that the associations between Al and Si were relatively stronger than that between Fe and Si in coprecipitates. In Al/Si coprecipitates, core-shell structures were developed with AlO6/AlO4 domains as the shells and Si frameworks polymerized from the SiO2 as the cores. However, Si framework remained relatively unchanged upon coprecipitation with Fe hydroxides in Fe/Si samples. The Si core with Al shell structure of Al/Si coprecipitates shielded the negative charges from SiO2 and thereby resulted in a higher adsorption capacity of selenite than Fe/Si coprecipitates.

  20. Molecular Structures of Al/Si and Fe/Si Coprecipitates and the Implication for Selenite Removal

    PubMed Central

    Chan, Ya-Ting; Kuan, Wen-Hui; Tzou, Yu-Min; Chen, Tsan-Yao; Liu, Yu-Ting; Wang, Ming-Kuang; Teah, Heng-Yi

    2016-01-01

    Aluminum and iron oxides have been often used in the coagulation processes during water purification due to their unique surface properties toward anions. In the presence of silica, the coprecipitation of Al/Si or Fe/Si might decrease the efficiency of wastewater purification and reuse. In this study, surface properties and molecular structures of Al/Si and Fe/Si coprecipitates were characterized using spectroscopic techniques. Also, the selenite removal efficiency of Al/Si and Fe/Si coprecipitates in relation to their surface and structural properties was investigated. While dissolved silicate increased with increasing pH from Fe/Si coprecipitates, less than 7% of silicate was discernible from Al/Si samples over the range from acidic to alkaline conditions. Our spectroscopic results showed that the associations between Al and Si were relatively stronger than that between Fe and Si in coprecipitates. In Al/Si coprecipitates, core-shell structures were developed with AlO6/AlO4 domains as the shells and Si frameworks polymerized from the SiO2 as the cores. However, Si framework remained relatively unchanged upon coprecipitation with Fe hydroxides in Fe/Si samples. The Si core with Al shell structure of Al/Si coprecipitates shielded the negative charges from SiO2 and thereby resulted in a higher adsorption capacity of selenite than Fe/Si coprecipitates. PMID:27095071

  1. Molecular Structures of Al/Si and Fe/Si Coprecipitates and the Implication for Selenite Removal.

    PubMed

    Chan, Ya-Ting; Kuan, Wen-Hui; Tzou, Yu-Min; Chen, Tsan-Yao; Liu, Yu-Ting; Wang, Ming-Kuang; Teah, Heng-Yi

    2016-04-20

    Aluminum and iron oxides have been often used in the coagulation processes during water purification due to their unique surface properties toward anions. In the presence of silica, the coprecipitation of Al/Si or Fe/Si might decrease the efficiency of wastewater purification and reuse. In this study, surface properties and molecular structures of Al/Si and Fe/Si coprecipitates were characterized using spectroscopic techniques. Also, the selenite removal efficiency of Al/Si and Fe/Si coprecipitates in relation to their surface and structural properties was investigated. While dissolved silicate increased with increasing pH from Fe/Si coprecipitates, less than 7% of silicate was discernible from Al/Si samples over the range from acidic to alkaline conditions. Our spectroscopic results showed that the associations between Al and Si were relatively stronger than that between Fe and Si in coprecipitates. In Al/Si coprecipitates, core-shell structures were developed with AlO6/AlO4 domains as the shells and Si frameworks polymerized from the SiO2 as the cores. However, Si framework remained relatively unchanged upon coprecipitation with Fe hydroxides in Fe/Si samples. The Si core with Al shell structure of Al/Si coprecipitates shielded the negative charges from SiO2 and thereby resulted in a higher adsorption capacity of selenite than Fe/Si coprecipitates.

  2. Molecular Structures of Al/Si and Fe/Si Coprecipitates and the Implication for Selenite Removal.

    PubMed

    Chan, Ya-Ting; Kuan, Wen-Hui; Tzou, Yu-Min; Chen, Tsan-Yao; Liu, Yu-Ting; Wang, Ming-Kuang; Teah, Heng-Yi

    2016-01-01

    Aluminum and iron oxides have been often used in the coagulation processes during water purification due to their unique surface properties toward anions. In the presence of silica, the coprecipitation of Al/Si or Fe/Si might decrease the efficiency of wastewater purification and reuse. In this study, surface properties and molecular structures of Al/Si and Fe/Si coprecipitates were characterized using spectroscopic techniques. Also, the selenite removal efficiency of Al/Si and Fe/Si coprecipitates in relation to their surface and structural properties was investigated. While dissolved silicate increased with increasing pH from Fe/Si coprecipitates, less than 7% of silicate was discernible from Al/Si samples over the range from acidic to alkaline conditions. Our spectroscopic results showed that the associations between Al and Si were relatively stronger than that between Fe and Si in coprecipitates. In Al/Si coprecipitates, core-shell structures were developed with AlO6/AlO4 domains as the shells and Si frameworks polymerized from the SiO2 as the cores. However, Si framework remained relatively unchanged upon coprecipitation with Fe hydroxides in Fe/Si samples. The Si core with Al shell structure of Al/Si coprecipitates shielded the negative charges from SiO2 and thereby resulted in a higher adsorption capacity of selenite than Fe/Si coprecipitates. PMID:27095071

  3. Co-precipitation of phosphate and iron limits mitochondrial phosphate availability in Saccharomyces cerevisiae lacking the yeast frataxin homologue (YFH1).

    PubMed

    Seguin, Alexandra; Santos, Renata; Pain, Debkumar; Dancis, Andrew; Camadro, Jean-Michel; Lesuisse, Emmanuel

    2011-02-25

    Saccharomyces cerevisiae cells lacking the yeast frataxin homologue (Δyfh1) accumulate iron in the mitochondria in the form of nanoparticles of ferric phosphate. The phosphate content of Δyfh1 mitochondria was higher than that of wild-type mitochondria, but the proportion of mitochondrial phosphate that was soluble was much lower in Δyfh1 cells. The rates of phosphate and iron uptake in vitro by isolated mitochondria were higher for Δyfh1 than wild-type mitochondria, and a significant proportion of the phosphate and iron rapidly became insoluble in the mitochondrial matrix, suggesting co-precipitation of these species after oxidation of iron by oxygen. Increasing the amount of phosphate in the medium decreased the amount of iron accumulated by Δyfh1 cells and improved their growth in an iron-dependent manner, and this effect was mostly transcriptional. Overexpressing the major mitochondrial phosphate carrier, MIR1, slightly increased the concentration of soluble mitochondrial phosphate and significantly improved various mitochondrial functions (cytochromes, [Fe-S] clusters, and respiration) in Δyfh1 cells. We conclude that in Δyfh1 cells, soluble phosphate is limiting, due to its co-precipitation with iron.

  4. An acetate precursor process for BSCCO (2223) thin films and coprecipitated powders

    NASA Technical Reports Server (NTRS)

    Haertling, Gene H.

    1992-01-01

    Since the discovery of high temperature superconducting oxides much attention has been paid to finding better and useful ways to take advantage of the special properties exhibited by these materials. One such process is the development of thin films for engineering applications. Another such process is the coprecipitation route to producing superconducting powders. An acetate precursor process for use in thin film fabrication and a chemical coprecipitation route to Bismuth based superconducting materials has been developed. Data obtained from the thin film process were inconclusive to date and require more study. The chemical coprecipitation method of producing bulk material is a viable method, and is preferred over the previously used solid state route. This method of powder production appears to be an excellent route to producing thin section tape cast material and screen printed devices, as it requires less calcines than the oxide route to produce quality powders.

  5. A nanoscale co-precipitation approach for property enhancement of Fe-base alloys

    PubMed Central

    Zhang, Zhongwu; Liu, Chain Tsuan; Miller, Michael K.; Wang, Xun-Li; Wen, Yuren; Fujita, Takeshi; Hirata, Akihiko; Chen, Mingwei; Chen, Guang; Chin, Bryan A.

    2013-01-01

    Precipitate size and number density are two key factors for tailoring the mechanical behavior of nanoscale precipitate-hardened alloys. However, during thermal aging, the precipitate size and number density change, leading to either poor strength or high strength but significantly reduced ductility. Here we demonstrate, by producing nanoscale co-precipitates in composition-optimized multicomponent precipitation-hardened alloys, a unique approach to improve the stability of the alloy against thermal aging and hence the mechanical properties. Our study provides compelling experimental evidence that these nanoscale co-precipitates consist of a Cu-enriched bcc core partially encased by a B2-ordered Ni(Mn, Al) phase. This co-precipitate provides a more complex obstacle for dislocation movement due to atomic ordering together with interphases, resulting in a high yield strength alloy without sacrificing alloy ductility. PMID:23429646

  6. The investigation of the compression and tension behavior of the cobalt ferrite magnetorheological fluids synthesized by co-precipitation

    NASA Astrophysics Data System (ADS)

    Molazemi, M.; Shokrollahi, H.; Hashemi, B.

    2013-11-01

    This paper aims at studying the effect of the particle size on the compression and tension behavior of the cobalt ferrite-based magnetorheological fluid (MRF). To achieve this goal, Co-ferrite nano-particles (CoFe2O4) with three different sizes, were synthesized by the chemical co-precipitation method and then two of them were mixed together. The X-Ray Diffraction (XRD) analysis, Scattering Electron Microscope (SEM), Laser Particle Size Analysis (LPSA) and Vibrating Sample Magnetometer (VSM) were carried out to study the phase analysis, particles morphology, particle distribution and magnetic properties, respectively. Then the compression and tension tests were conducted on MRFs containing silicon oil as a carrier. The results showed that the highest values of the compression and tension strengths of fluids correspond to the larger particle sizes (550 nm) with 1.241 and 0.594 MPa, respectively. Furthermore, the compression and tension strengths of the mixed one (1.153 and 0.388 MPa) containing 60 and 300 nm samples are higher than its components with 0.431 and 0.249 MPa, as well as 0.694 and 0.367 MPa, respectively.

  7. Coprecipitation of arsenate with metal oxides. 2. Nature, mineralogy, and reactivity of iron(III) precipitates.

    PubMed

    Violante, Antonio; Del Gaudio, Stefania; Pigna, Massimo; Ricciardella, Mariarosaria; Banerjee, Dipanjan

    2007-12-15

    Coprecipitation of arsenic with iron or aluminum occurs in natural environments and is a remediation technology used to remove this toxic metalloid from drinking water and hydrometallurgical solutions. In this work, we studied the nature, mineralogy, and reactivity toward phosphate of iron-arsenate coprecipitates formed at As(V)/Fe(III) molar ratios (R) of 0, 0.01, or 0.1 and at pH 4.0, 7.0, and 10.0 aged for 30 or 210 days at 50 degrees C and studied the desorption of arsenate. At R = 0, goethite and hematite (with ferrihydrite at pH 4.0 and 7.0) crystallized, whereas at R = 0.01, the formation of ferrihydrite increased and hematite crystallization was favored over goethite. In some samples, the morphology of hematite changed from rounded platy crystals to ellipsoids. At R = 0.1, ferrihydrite formed in all the coprecipitates and remained unchanged even after 210 days of aging. The surface area and chemical composition of the precipitates were affected by pH, R, and aging. Chemical dissolution of the samples showed that arsenate was present mainly in ferrihydrite, but at R = 0.01, it was partially incorporated into the structures of crystalline Fe oxides. The sorption of phosphate on to the coprecipitates was affected not only by the mineralogy and surface area of the samples but also by the amounts of arsenate present in the oxides. The samples formed at pH 4.0 and 7.0 and at R = 0.1 sorbed lower amounts of phosphate than the precipitates obtained at R = 0 or 0.01, despite the former having a larger surface area and showing only a presence of short-range ordered materials. This is mainly due to the fact that in the coprecipitates at R = 0.1 arsenate occupied many sorption sites, thus preventing phosphate sorption. Less than 20% of the arsenate present in the coprecipitates formed at R = 0.1 was removed by phosphate and more from the samples synthesized at pH 7.0 or 10.0 than at pH 4.0. Moreover, we found that more arsenate was desorbed by phosphate from a

  8. Strontium Co-precipitation During Biomineralization of Calcite in Porous Media Using Differing Treatment Strategies

    NASA Astrophysics Data System (ADS)

    Lauchnor, E. G.; Schultz, L.; Mitchell, A.; Cunningham, A. B.; Gerlach, R.

    2013-12-01

    The process of ureolytically-induced calcium carbonate mineralization has been shown in laboratory studies to be effective in co-precipitation of heavy metals and radionuclides. During this process, the microbially catalyzed hydrolysis of urea increases alkalinity and pH, thus promoting CaCO3 precipitation in the presence of dissolved calcium. One proposed application of biomineralization includes the remediation of radionuclides such as strontium, which can be co-precipitated in situ within calcite. Strontium is of concern at several US DOE sites where it is a radioactive product of uranium fission and groundwater contaminant. Our research focuses on promoting attached bacteria, or biofilms, in subsurface environments where they serve as immobilized catalysts in biomineralization and can aide in co-precipitation of some contaminants. In this work, flat plate reactors with 1 mm etched flow channels designed to mimic a porous medium environment were used. Reactors were inoculated with the model ureolytic bacterium Sporosarcina pasteurii and addition of urea, calcium and strontium containing fluid was performed to induce biomineralization. Continuous flow and stopped-flow injection strategies were investigated to evaluate differences in strontium co-precipitation efficiency. During stopped-flow experiments, injection of cementation fluid containing urea, Ca2+ and Sr2+ was alternated with growth nutrients for stimulation of microbial activity. Control parameters such as urea and calcium concentration and injection flow rate are currently being varied to optimize rate and efficiency of strontium co-precipitation. Ureolytically induced calcite precipitation and strontium incorporation in the calcite was verified by chemical and mineralogical analyses, including X-ray diffraction and ICP-MS. Strontium co-precipitation efficiency was similar under different injection strategies. Alternating calcium-containing fluid with growth nutrients allowed for continued viability of

  9. Stabilization of extracellular polymeric substances ( Bacillus subtilis) by adsorption to and coprecipitation with Al forms

    NASA Astrophysics Data System (ADS)

    Mikutta, Robert; Zang, Ulrich; Chorover, Jon; Haumaier, Ludwig; Kalbitz, Karsten

    2011-06-01

    Extracellular polymeric substances (EPS) are continuously produced by bacteria during their growth and metabolism. In soils, EPS are bound to cell surfaces, associated with biofilms, or released into solution where they can react with other solutes and soil particle surfaces. If such reaction results in a decrease in EPS bioaccessibility, it may contribute to stabilization of microbial-derived organic carbon (OC) in soil. Here we examined: (i) the chemical fractionation of EPS produced by a common Gram positive soil bacterial strain ( Bacillus subtilis) during reaction with dissolved and colloidal Al species and (ii) the resulting stabilization against desorption and microbial decay by the respective coprecipitation (with dissolved Al) and adsorption (with Al(OH) 3(am)) processes. Coprecipitates and adsorption complexes obtained following EPS-Al reaction as a function of pH and ionic strength were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The stability of adsorbed and coprecipitated EPS against biodegradation was assessed by mineralization experiments for 1100 h. Up to 60% of the initial 100 mg/L EPS-C was adsorbed at the highest initial molar Al:C ratio (1.86), but this still resulted only in a moderate OC mass fraction in the solid phase (17 mg/g Al(OH) 3(am)). In contrast, while coprecipitation by Al was less efficient in removing EPS from solution (maximum values of 33% at molar Al:C ratios of 0.1-0.2), the OC mass fraction in the solid product was substantially larger than that in adsorption complexes. Organic P compounds were preferentially bound during both adsorption and coprecipitation. Data are consistent with strong ligand exchange of EPS phosphoryl groups during adsorption to Al(OH) 3(am), whereas for coprecipitation weaker sorption mechanisms are also involved. X-ray photoelectron analyses indicate an intimate mixing of EPS with Al in the coprecipitates, which is not observed in the case

  10. Defect related microstructure, optical and photoluminescence behaviour of Ni, Cu co-doped ZnO nanoparticles by co-precipitation method

    NASA Astrophysics Data System (ADS)

    Anbuselvan, D.; Muthukumaran, S.

    2015-04-01

    In the present study Ni-doped ZnO and Ni, Cu-doped ZnO nanoparticles were successfully synthesized by co-precipitation method. Structural studies confirmed the dominant presence of hexagonal wurtzite ZnO phase at lower Cu concentration and CuO phase was observed at higher Cu (Cu = 5%) concentration. The existence of Cu2+ ions were dominant at Cu ⩽ 3% (responsible for lattice shrinkage) and the presence of Cu+ ions were dominant at Cu > 3% (responsible for lattice expansion). The change in UV-visible absorption and energy gap were discussed by secondary phase generation and charge carrier density. The low absorption loss and high transmittance at Cu = 3% doped samples is used as potential candidate for opto-electronic devices. The increase of green band intensity and decrease of UV band at higher Cu concentration confirmed the existence of more defect related states.

  11. RATES OF HYDROUS FERRIC OXIDE CRYSTALLIZATION AND THE INFLUENCE ON COPRECIPITATED ARSENATE

    EPA Science Inventory

    Arsenate coprecipitated with hydrous ferric oxide (HFO) was stabilized against dissolution during transformation of HFO to more crystalline iron (hydr)oxides. The rate of arsenate stabilization approximately coincided with the rate of HFO transformation at pH 6 and 40 ?C. Compa...

  12. Optimization of ferric hydroxide coprecipitation process for selenium removal from petroleum refinery stripped four water

    SciTech Connect

    Gerhardt, M.B.; Marrs, D.R.; Roehl, R.

    1996-12-31

    Iron coprecipitation was used in bench-scale tests to remove selenium from stripped sour water generated by two petroleum refineries. Chlorine dioxide and hydrogen peroxide were found to convert selenocyanate in the stripped sour water to selenite, which can be removed by iron coprecipitation. An iodometric titration procedure was developed to determine the required oxidant dose. Iron coprecipitation reduced selenium concentrations by 40 to 99 percent in stripped sour water after chlorine dioxide pretreatment Removal was less effective with hydrogen peroxide as the oxidant: total selenium concentrations were reduced by 28 to 92 percent in stripped sour water after hydrogen peroxide pretreatment. Highest removals were obtained at the highest oxidant and iron doses. Sludges produced in coprecipitation tests were hazardous under California regulations. Ozone oxidized selenocyanate but prevented ferric hydroxide precipitation or coagulation. Air was ineffective at selenocyanate oxidation. Repeatedly contacting iron hydroxide with stripped sour water pretreated with hydrogen peroxide, in a simulation of a countercurrent adsorption process, increased the selenium adsorbed on the solids from 32 to 147 pg selenium per mg of iron, but some of the adsorbed selenite was oxidized to selenate and desorbed back into solution.

  13. Stabilization of microbial residues by co-precipitation with Fe and Al oxides

    NASA Astrophysics Data System (ADS)

    Miltner, Anja; Achtenhagen, Jan; Kästner, Matthias

    2016-04-01

    Recent studies have shown that microbial residues contribute significantly to soil organic matter (SOM) formation. This material, however, is readily degradable and thus needs to be stabilized in soil. We hypothesize that the interaction with minerals, in particular co-precipitation with metal oxyhydroxides, plays an important role in stabilization of cell envelope material. We therefore analyzed the mineralization of 14C-labelled Escherichia coli cells and cell envelope fragments during incubation of the cell materials alone or after co-precipitation with either Fe or Al oxyhydroxide. We also tested the effect of environmental conditions, in particular oxygen supply and redox potential, on the stabilizing effect of the mineral phases. Co-precipitation with both Fe and Al oxyhydroxides decreased the mineralization significantly, indicating strong protection of biomass and biomass-derived fragments. Surprisingly, the mineralization of intact cells was higher than that of cell envelope fragments. This points to a higher recalcitrance of the cell envelope fragments, which therefore may be selectively enriched in SOM. Reductive conditions obtained after water-logging combined with excessive supply of an easily available carbon source resulted in increased mineralization in the treatments containing Fe oxyhydroxides, due to reductive dissolution of the Fe oxyhydroxide and thus loss of the stabilizing agent. We therefore conclude that co-precipitation with and incrustation by Fe or Al oxyhydroxides is a relevant stabilization mechanism for microbial residues. The same mechanism also may apply for SOM in general.

  14. Bacterially induced calcium carbonate precipitation and strontium coprecipitation in a porous media flow system.

    PubMed

    Lauchnor, Ellen G; Schultz, Logan N; Bugni, Steven; Mitchell, Andrew C; Cunningham, Alfred B; Gerlach, Robin

    2013-02-01

    Strontium-90 is a principal radionuclide contaminant in the subsurface at several Department of Energy sites in the Western U.S., causing a threat to groundwater quality in areas such as Hanford, WA. In this work, we used laboratory-scale porous media flow cells to examine a potential remediation strategy employing coprecipitation of strontium in carbonate minerals. CaCO(3) precipitation and strontium coprecipitation were induced via ureolysis by Sporosarcina pasteurii in two-dimensional porous media reactors. An injection strategy using pulsed injection of calcium mineralization medium was tested against a continuous injection strategy. The pulsed injection strategy involved periods of lowered calcite saturation index combined with short high fluid velocity flow periods of calcium mineralization medium followed by stagnation (no-flow) periods to promote homogeneous CaCO(3) precipitation. By alternating the addition of mineralization and growth media the pulsed strategy promoted CaCO(3) precipitation while sustaining the ureolytic culture over time. Both injection strategies achieved ureolysis with subsequent CaCO(3) precipitation and strontium coprecipitation. The pulsed injection strategy precipitated 71-85% of calcium and 59% of strontium, while the continuous injection was less efficient and precipitated 61% of calcium and 56% of strontium. Over the 60 day operation of the pulsed reactors, ureolysis was continually observed, suggesting that the balance between growth and precipitation phases allowed for continued cell viability. Our results support the pulsed injection strategy as a viable option for ureolysis-induced strontium coprecipitation because it may reduce the likelihood of injection well accumulation caused by localized mineral plugging while Sr coprecipitation efficiency is maintained in field-scale applications. PMID:23282003

  15. Bacterially induced calcium carbonate precipitation and strontium coprecipitation in a porous media flow system.

    PubMed

    Lauchnor, Ellen G; Schultz, Logan N; Bugni, Steven; Mitchell, Andrew C; Cunningham, Alfred B; Gerlach, Robin

    2013-02-01

    Strontium-90 is a principal radionuclide contaminant in the subsurface at several Department of Energy sites in the Western U.S., causing a threat to groundwater quality in areas such as Hanford, WA. In this work, we used laboratory-scale porous media flow cells to examine a potential remediation strategy employing coprecipitation of strontium in carbonate minerals. CaCO(3) precipitation and strontium coprecipitation were induced via ureolysis by Sporosarcina pasteurii in two-dimensional porous media reactors. An injection strategy using pulsed injection of calcium mineralization medium was tested against a continuous injection strategy. The pulsed injection strategy involved periods of lowered calcite saturation index combined with short high fluid velocity flow periods of calcium mineralization medium followed by stagnation (no-flow) periods to promote homogeneous CaCO(3) precipitation. By alternating the addition of mineralization and growth media the pulsed strategy promoted CaCO(3) precipitation while sustaining the ureolytic culture over time. Both injection strategies achieved ureolysis with subsequent CaCO(3) precipitation and strontium coprecipitation. The pulsed injection strategy precipitated 71-85% of calcium and 59% of strontium, while the continuous injection was less efficient and precipitated 61% of calcium and 56% of strontium. Over the 60 day operation of the pulsed reactors, ureolysis was continually observed, suggesting that the balance between growth and precipitation phases allowed for continued cell viability. Our results support the pulsed injection strategy as a viable option for ureolysis-induced strontium coprecipitation because it may reduce the likelihood of injection well accumulation caused by localized mineral plugging while Sr coprecipitation efficiency is maintained in field-scale applications.

  16. Cu Binding to Iron Oxide-Organic Matter Coprecipitates in Solid and Dissolved Phases

    NASA Astrophysics Data System (ADS)

    Vadas, T. M.; Koenigsmark, F.

    2015-12-01

    Recent studies indicate that Cu is released from wetlands following storm events. Assymetrical field flow field fractionation (AF4) analyses as well as total and dissolved metal concentration measurements suggest iron oxide-organic matter complexes control Cu retention and release. Coprecipitation products of Fe oxide and organic matter were prepared under conditions similar to the wetland to assess Cu partitioning to and availability from solid phases that settle from solution as well as phases remaining suspended. Cu coprecipitation and sorption to organomineral precipitation solids formed at different Fe:organic carbon (OC) ratios were compared for net Cu removal and extractability. As more humic acid was present during precipitation of Fe, TEM images indicated smaller Fe oxide particles formed within an organic matrix as expected. In coprecipitation reactions, as the ratio of Fe:OC decreased, more Cu was removed from solution at pH 5.5 and below. However, in sorption reactions, there was an inhibition of Cu removal at low OC concentrations. As the pH increased from 5.5 to 7 and as solution phase OC concentration increased, more Cu remained dissolved in both coprecipitation and sorption reactions. The addition of Ca2+, glycine, histidine and citric acid or lowering the pH resulted in more extractable Cu from the coprecipitation compared with the sorption reactions. The variations in Cu extraction were likely due to a combination of a more amorphous structure in CPT products, and the relative abundance of available Fe oxide or OC binding sites. Suspended Fe oxide-organic matter coprecipitates were assessed using AF4 coupled to online TOC analysis and ICP-MS. In laboratory prepared samples, Cu was observed in a mixture of small 1-5 nm colloids of Fe oxide-organic matter precipitates, but the majority was observed in larger organic matter colloids and were not UV absorbing, suggesting more aliphatic carbon materials. In field samples, up to 60% of the dissolved Cu

  17. Study of de-watering from the gelatinous precipitate formed during co-precipitation of Nd-YAG powder

    SciTech Connect

    Karmakar, Sanjib; Sharma, Rachna; Pathak, S. K.; Gupta, S. M.; Gupta, P. K.

    2013-02-05

    Neodymium doped Yttrium Aluminium Garnet (Nd:YAG) ceramics have been synthesised using coprecipitation technique and high temperature vacuum sintering. Gelatinous like precipitates were obtained when precursors of Nd, Al and Yb-nitrate solutions are co-precipitated using ammonia co-precipitant. De-watering from the gelatinous like precipitates is a big challenge and it possesses difficulty in filtration. Evaporation of water by heating resulted in strong agglomerated powder. Different agents were used to ease the filtration process, which is correlated with the phase in the calcined powder.

  18. Microstructure, optical and FTIR studies of Ni, Cu co-doped ZnO nanoparticles by co-precipitation method

    NASA Astrophysics Data System (ADS)

    Ashokkumar, M.; Muthukumaran, S.

    2014-11-01

    Zn0.96-xCu0.04NixO (0 ⩽ x ⩽ 0.04) nanoparticles were synthesized by co-precipitation method. The X-ray diffraction pattern showed the crystalline nature of prepared nanoparticles with hexagonal wurtzite structure. The average crystal size is decreased from 27 to 22.7 nm when Ni concentration is increased from 0% to 2% due to the suppression of nucleation and subsequent growth of ZnO by Ni-doping. The increased crystal size from 22.7 to 25.8 nm (ΔD ∼ 3.1 nm) by Ni-doping from 2% to 4% is due to the creation of distortion centers and Zn/Ni interstitials. The cell parameters and volume of the lattice showed solubility limit at 2% of Ni doping. The energy dispersive X-ray spectra confirmed the presence of Cu and Ni in Zn-O. The optical absorption spectra showed that the absorption was increased up to Ni = 2% due to the creation of carrier concentration by Ni-doping and decreased beyond 2% due to the presence of more defects and interstitials in the Zn-Ni-Cu-O lattice. The observed red shift of energy gap from 3.65 eV (Ni = 0%) to 3.59 eV (Ni = 2%, ΔEg ≈ 0.06 eV) is explained by sp-d exchange interactions between the band electrons and the localized d-electrons of the Ni2+ ions. The blue shift of energy gap from 3.59 eV (Ni = 2%) to 3.67 eV (Ni = 4%, ΔEg ≈ 0.08 eV) is explained by Burstein-Moss effect. Presence of chemical bonding was confirmed by FTIR spectra.

  19. Attapulgite-Fe 3O 4 magnetic nanoparticles via co-precipitation technique

    NASA Astrophysics Data System (ADS)

    Liu, Yushan; Liu, Peng; Su, Zhixing; Li, Fashen; Wen, Fusheng

    2008-12-01

    The attapulgite/Fe 3O 4 magnetic nanoparticles (ATP-Fe 3O 4) were prepared by co-precipitation technique in the aqueous suspension of attapulgite pre-modified with FeCl 3. The co-precipitation occurred by ammonia in presence of ferrous chloride at 90 °C under magnetic stirring. Morphology observation showed that the Fe 3O 4 nanoparticles were absorbed to attapulgite nano-needles' surfaces and their dispersibilities in water was also studied. The ATP-Fe 3O 4 particles had been characterized with Fourier transform infrared (FT-IR) spectroscopy analysis, X-ray diffraction (XRD), pore surface area (BET), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM).

  20. Synthesis of layered double hydroxide nanosheets by coprecipitation using a T-type microchannel reactor

    SciTech Connect

    Pang, Xiujiang; Sun, Meiyu; Ma, Xiuming; Hou, Wanguo

    2014-02-15

    The synthesis of Mg{sub 2}Al–NO{sub 3} layered double hydroxide (LDH) nanosheets by coprecipitation using a T-type microchannel reactor is reported. Aqueous LDH nanosheet dispersions were obtained. The LDH nanosheets were characterized by X-ray diffraction, transmission electron microscopy, atomic force microscopy and particle size analysis, and the transmittance and viscosity of LDH nanosheet dispersions were examined. The two-dimensional LDH nanosheets consisted of 1–2 brucite-like layers and were stable for ca. 16 h at room temperature. In addition, the co-assembly between LDH nanosheets and dodecyl sulfate (DS) anions was carried out, and a DS intercalated LDH nanohybrid was obtained. To the best of our knowledge, this is the first report of LDH nanosheets being directly prepared in bulk aqueous solution. This simple, cheap method can provide naked LDH nanosheets in high quantities, which can be used as building blocks for functional materials. - Graphical abstract: Layered double hydroxide (LDH) nanosheets were synthesized by coprecipitation using a T-type microchannel reactor, and could be used as basic building blocks for LDH-based functional materials. Display Omitted - Highlights: • LDH nanosheets were synthesized by coprecipitation using a T-type microchannel reactor. • Naked LDH nanosheets were dispersed in aqueous media. • LDH nanosheets can be used as building blocks for functional materials.

  1. Coprecipitation of Sr, Ni and U with CaCO{sub 3}: An experimental study

    SciTech Connect

    Carlsson, T.; Aalto, H.

    1996-08-01

    At the Finnish candidate sites for a nuclear waste repository, calcite (CaCO{sub 3}) is a common fracture mineral that may participate in coprecipitation processes. The objective of this preliminary work was to study the coprecipitation of the trace elements Sr, Ni, and U with CaCO{sub 3} under controlled conditions. The experiments were made in a titration vessel at room temperature under pure N{sub 2} or a 0.1% CO{sub 2}/N{sub 2} mixture. The water phase contained CaCl{sub 2} (0.01M) and NaCl (0.05 M) to which trace amounts of Ni{sup 2+}, Sr{sup 2+} and UO{sub 2}{sup 2+} were initially added. CaCO{sub 3} was precipitated by the addition of Na{sub 2}CO{sub 3} and the use of CaCO{sub 3} seed crystals. When about 10{sup {minus}4} mol of precipitate had formed, the solution and solid phases were analyzed with ICP-MS. The results seem to indicate that Ni coprecipitated with CaCO{sub 3} under the experimental conditions, while U did not. In the case of Sr, further data are needed in order to make any conclusions from the experiments.

  2. Co-precipitation of phosphate and carbonate minerals: geological and ecological implications

    NASA Astrophysics Data System (ADS)

    Sanchez-Román, Monica; McKenzie, Judith; Vasconcelos, Crisogono

    2015-04-01

    Microorganisms play an important role in natural environments by controlling the metal cations (e.g., Ca2+, Mg2+, Fe2+) and the anions (CO32-, NH4+, PO43-) that precipitate as biominerals (e.g., carbonates, phosphates). In contrast to phosphate minerals, precipitation of carbonate minerals by bacteria has been widely studied in culture experiments and in natural environments. Moreover, studies of sedimentary phosphate minerals and their geological and ecological implications are rare. Nevertheless, phosphate minerals frequently co-precipitate with carbonates in culture experiments and in natural systems. In the present work, we investigate how microorganisms control the mineralogy and geochemistry of phosphate and carbonate minerals. For this, culture experiments were performed to study the co-precipitation of phosphate and carbonate minerals using aerobic heterotrophic bacteria at sedimentary Earth's surface conditions. Ca-Mg carbonate (dolomite, Mg-calcite) and/or Mg-carbonate (hydromagnesite) precipitated with Mg-phosphate (struvite). In most of the cultures, phosphate was the dominant mineral phase found in the bacterial precipitates and carbonates precipitated after phosphate phases. Notably, in all the cultures, we found a mixture of phosphate and carbonate minerals. This study shines new light into the microbial diagenetic processes involved in the co-precipitation of phosphate and carbonate minerals and links the P and C cycles.

  3. (228)Ra and (226)Ra measurement on a BaSO4 co-precipitation source.

    PubMed

    Medley, Peter; Martin, Paul; Bollhöfer, Andreas; Parry, David

    2014-10-14

    One of the most commonly-used methods for determination of (226)Ra, particularly in water samples, utilises co-precipitation of Ra with BaSO4, followed by microfiltration to produce a source for alpha counting. This paper describes two extensions to BaSO4 co-precipitation methods which enable determination of (228)Ra using the same source. The adaptations presented here do not introduce any contaminants that will affect the separation of radium or alpha counting for (226)Ra, and can be used for re-analysis of already existing sources prepared by BaSO4 co-precipitation. The first adaptation uses detection of (228)Ac on the source by gamma spectrometry. The detection efficiency is high, allowing analysis of water samples at sufficiently low activity to be suitable in testing for compliance with drinking water quality standards. As (228)Ac grows in quickly, taking less than 2 days to reach equilibrium with the (228)Ra parent, this can also be useful in radiological emergency response situations. The second adaptation incorporates a method for the digestion of BaSO4 sources, allowing separation of thorium and subsequent determination of (228)Th activity. Although ingrowth periods for (228)Th can be lengthy, very low detection limits for (228)Ra can be achieved with this technique.

  4. In vitro release, rheological, and stability studies of mefenamic acid coprecipitates in topical formulations.

    PubMed

    Ahmed, Tarek A; Ibrahim, Hany M; Ibrahim, Fathy; Samy, Ahmed M; Fetoh, Ehab; Nutan, Mohammad T H

    2011-10-01

    A suitable topical formulation of mefenamic acid was developed in order to eliminate the gastrointestinal disorders associated with its oral administration. Drug coprecipitates prepared with different polymers at various drug-to-polymer ratios improved drug solubility and dissolution compared to pure drug and physical mixtures. PVP polymers (ratio 1:4) produced the best results. Aqueous ionic cream, ointments of absorption and water soluble bases and gels of methylcellulose, carboxymethylcellulose sodium, HPMC, Carbopol® 934 and 940, and Pluronic® F127 bases containing 1-10% drug as coprecipitates of PVP polymers (1:4) were prepared. The highest drug release was achieved at 1% drug concentration from water soluble base and methylcellulose among cream/ointment and gel bases, respectively. Gels, in general yielded better release than creams/ointments. All tested medicated creams/ointments exhibited plastic flow while all gels conformed to pseudoplasticity. Most of them showed thixotropy, a desired property of topical preparations. Stability studies revealed that HPMC and methylcellulose had the smallest changes in drug content, viscosity, and pH among the formulations. Considering drug release, rheological properties, and stability, methylcellulose gel containing 1% drug as coprecipitates of PVP K90 was the best among the studied formulations, was promising for improving bioavailability of mefenamic acid and can be used in future studies.

  5. (228)Ra and (226)Ra measurement on a BaSO4 co-precipitation source.

    PubMed

    Medley, Peter; Martin, Paul; Bollhöfer, Andreas; Parry, David

    2014-10-14

    One of the most commonly-used methods for determination of (226)Ra, particularly in water samples, utilises co-precipitation of Ra with BaSO4, followed by microfiltration to produce a source for alpha counting. This paper describes two extensions to BaSO4 co-precipitation methods which enable determination of (228)Ra using the same source. The adaptations presented here do not introduce any contaminants that will affect the separation of radium or alpha counting for (226)Ra, and can be used for re-analysis of already existing sources prepared by BaSO4 co-precipitation. The first adaptation uses detection of (228)Ac on the source by gamma spectrometry. The detection efficiency is high, allowing analysis of water samples at sufficiently low activity to be suitable in testing for compliance with drinking water quality standards. As (228)Ac grows in quickly, taking less than 2 days to reach equilibrium with the (228)Ra parent, this can also be useful in radiological emergency response situations. The second adaptation incorporates a method for the digestion of BaSO4 sources, allowing separation of thorium and subsequent determination of (228)Th activity. Although ingrowth periods for (228)Th can be lengthy, very low detection limits for (228)Ra can be achieved with this technique. PMID:25464199

  6. Common Carrier Services.

    ERIC Educational Resources Information Center

    Federal Communications Commission, Washington, DC.

    After outlining the Federal Communications Commission's (FCC) responsibility for regulating interstate common carrier communication (non-broadcast communication whose carriers are required by law to furnish service at reasonable charges upon request), this information bulletin reviews the history, technological development, and current…

  7. Surface chemistry of ferrihydrite: Part 2. Kinetics of arsenate adsorption and coprecipitation

    USGS Publications Warehouse

    Fuller, C.C.; Dadis, J.A.; Waychunas, G.A.

    1993-01-01

    The kinetics of As(V) adsorption by ferrihydrite was investigated in coprecipitation and postsynthesis adsorption experiments conducted in the pH range 7.5-9.0. In coprecipitation experiments, As(V) was present in solution during the hydrolysis and precipitation of iron. In adsorption experiments, a period of rapid (<5 min) As(V) uptake from solution was followed by continued uptake for at least eight days, as As(V) diffused to adsorption sites on ferrihydrite surfaces within aggregates of colloidal particles. The time dependence of As(V) adsorption is well described by a general model for diffusion into a sphere if a subset of surface sites located near the exterior of aggregates is assumed to attain adsorptive equilibrium rapidly. The kinetics of As(V) desorption after an increase in pH were also consistent with diffusion as a rate-limiting process. Aging of pure ferrihydrite prior to As(V) adsorption caused a decrease in adsorption sites on the precipitate owing to crystallite growth. In coprecipitation experiments, the initial As(V) uptake was significantly greater than in post-synthesis adsorption experiments, and the rate of uptake was not diffusion limited because As(V) was coordinated by surface sites before crystallite growth and coagulation processes could proceed. After the initial adsorption, As(V) was slowly released from coprecipitates for at least one month, as crystallite growth caused desorption of As(V). Adsorption densities as high as 0.7 mole As(V) per mole of Fe were measured in coprecipitates, in comparison to 0.25 mole As(V) per mole of Fe in post-synthesis adsorption experiments. Despite the high Concentration of As(V) in the precipitates, EXAFS spectroscopy (Waychunas et al., 1993) showed that neither ferric arsenate nor any other As-bearing surface precipitate or solid solution was formed. The high adsorption densities are possible because the ferrihydrite particles are extremely small, approaching the size of small dioctahedral chains at

  8. Composite carrier bar device

    SciTech Connect

    Felder, D.W.

    1981-09-01

    A composite carrier bar is disclosed for oil well pumping units that utilize sucker rod to operate bottom hole pumps. The bar includes a recessed cavity for receiving a hydraulic ram to operate as a polish rod jack and also a secondary carrier bar for receiving a secondary polish rod clamp for use in respacing bottom hole pumps and serve as a safety clamp during operation.

  9. Evaluation of Co-precipitation Processes for the Synthesis of Mixed-Oxide Fuel Feedstock Materials

    SciTech Connect

    Collins, Emory D; Voit, Stewart L; Vedder, Raymond James

    2011-06-01

    The focus of this report is the evaluation of various co-precipitation processes for use in the synthesis of mixed oxide feedstock powders for the Ceramic Fuels Technology Area within the Fuels Cycle R&D (FCR&D) Program's Advanced Fuels Campaign. The evaluation will include a comparison with standard mechanical mixing of dry powders and as well as other co-conversion methods. The end result will be the down selection of a preferred sequence of co-precipitation process for the preparation of nuclear fuel feedstock materials to be used for comparison with other feedstock preparation methods. A review of the literature was done to identify potential nitrate-to-oxide co-conversion processes which have been applied to mixtures of uranium and plutonium to achieve recycle fuel homogeneity. Recent studies have begun to study the options for co-converting all of the plutonium and neptunium recovered from used nuclear fuels, together with appropriate portions of recovered uranium to produce the desired mixed oxide recycle fuel. The addition of recycled uranium will help reduce the safeguard attractiveness level and improve proliferation resistance of the recycled fuel. The inclusion of neptunium is primarily driven by its chemical similarity to plutonium, thus enabling a simple quick path to recycle. For recycle fuel to thermal-spectrum light water reactors (LWRs), the uranium concentration can be {approx}90% (wt.), and for fast spectrum reactors, the uranium concentration can typically exceed 70% (wt.). However, some of the co-conversion/recycle fuel fabrication processes being developed utilize a two-step process to reach the desired uranium concentration. In these processes, a 50-50 'master-mix' MOX powder is produced by the co-conversion process, and the uranium concentration is adjusted to the desired level for MOX fuel recycle by powder blending (milling) the 'master-mix' with depleted uranium oxide. In general, parameters that must be controlled for co-precipitation

  10. Controllable synthesis and characterization of cadmium molybdate octahedral nanocrystals by coprecipitation method

    SciTech Connect

    Shahri, Zahra; Sobhani, Azam; Salavati-Niasari, Masoud

    2013-10-15

    Graphical abstract: CdMoO{sub 4} nanocrystals have been synthesized via coprecipitation method by using Cd(Sal){sub 2} and (NH{sub 4}){sub 6}Mo{sub 7}O{sub 24}·4H{sub 2}O as starting materials in water. Effects of temperature, reaction time, solvent, surfactant, cadmium and molybdate sources were investigated to reach optimum condition. It was found that particle size, morphology and phase of the final products could be greatly influenced via these parameters. - Highlights: • A facile coprecipitation method was successfully employed to prepare CdMoO{sub 4}. • The effects of some parameters were investigated. • PEG600, PVP, SDS and CTAB were used as surfactant. • Optimum condition for preparation CdMoO{sub 4} nanocrystals was investigated. - Abstract: Cadmium molybdate (CdMoO{sub 4}) nanocrystals have been successfully synthesized via coprecipitation method by using Cd(Sal){sub 2} (Sal = salicylidene) and (NH{sub 4}){sub 6}Mo{sub 7}O{sub 24}·4H{sub 2}O as starting materials in water as solvent. Effects of temperature, reaction time, solvent, surfactant and cadmium source were investigated to reach optimum condition. It was found that particle size, morphology and phase of the final products could be greatly influenced via these parameters. The products were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, photoluminescence (PL) spectroscopy, energy dispersive X-ray microanalysis (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM)

  11. Novel vaginal controlled-delivery systems incorporating coprecipitates of nonoxynol-9.

    PubMed

    Digenis, G A; Nosek, D; Mohammadi, F; Darwazeh, N B; Anwar, H S; Zavos, P M

    1999-08-01

    The purpose of this study was to formulate Nonoxynol-9 (N-9) into a solid coprecipitate form which can be used in preparing pharmaceutically attractive and nonirritating vaginal controlled-release delivery systems (DDSs) such as gelatin capsules (HGC) and tablets. N-9 was coprecipitated with polyvinylpyrrolidone (PVP) with or without iodine to produce solid powders which were incorporated into either (a) bilayer tablet DDSs which possess a fast- (outer) and slow- (inner core) releasing compartment, and (b) HGC DDSs (named Triad HGC) composed of fast- (outer), intermediate- (granules), and slow- (pellets) releasing compartments. The rates of release of iodine and/or [14C]N-9 from the two DDSs were studied in vitro in phosphate buffer at pH 5.0, in human seminal plasma and in vivo after intravaginal administration in rabbits. In all of the above-described release studies, the DDSs were shown to release their N-9 or iodine content rapidly, reaching spermicidal levels within 3 min. This was further substantiated by experiments in which the DDSs were introduced in whole human semen containing live spermatozoa. Complete spermicidal kill was obtained in less than 1 min and in less than 3 min from the bilayer tablet and the Triad HGC, respectively. Furthermore, the release of N-9 from the two DDSs was shown to continue for at least 4 hr in buffers (pH 5.0), human seminal fluid, and after intravaginal administration in rabbits. The resulting powder from the coprecipitation of N-9 and PVP (K-30) can be appropriately formulated into a controlled-released HGC or bilayer tablet to produce vaginal controlled-release DDSs which are nonirritating and have the potential to become effective spermicidal products. PMID:10434288

  12. Co-precipitation of dissolved organic matter by calcium carbonate in Pyramid Lake, Nevada

    USGS Publications Warehouse

    Leenheer, Jerry A.; Reddy, Michael M.

    2008-01-01

    Our previous research has demonstrated that dissolved organic matter (DOM) influences calcium carbonate mineral formation in surface and ground water. To better understand DOM mediation of carbonate precipitation and DOM co-precipitation and/or incorporation with carbonate minerals, we characterized the content and speciation of DOM in carbonate minerals and in the lake water of Pyramid Lake, Nevada, USA. A 400-gram block of precipitated calcium carbonate from the Pyramid Lake shore was dissolved in 8 liters of 10% acetic acid. Particulate matter not dissolved by acetic acid was removed by centrifugation. DOM from the carbonate rock was fractionated into nine portions using evaporation, dialysis, resin adsorption, and selective precipitations to remove acetic acid and inorganic constituents. The calcium carbonate rock contained 0.23% DOM by weight. This DOM was enriched in polycarboxylic proteinaceous acids and hydroxy-acids in comparison with the present lake water. DOM in lake water was composed of aliphatic, alicyclic polycarboxylic acids. These compound classes were found in previous studies to inhibit calcium carbonate precipitation. DOM fractions from the carbonate rock were 14C-age dated at about 3,100 to 3,500 years before present. The mechanism of DOM co-precipitation and/or physical incorporation in the calcium carbonate is believed to be due to formation of insoluble calcium complexes with polycarboxylic proteinaceous acids and hydroxy-acids that have moderately large stability constants at the alkaline pH of the lake. DOM co-precipitation with calcium carbonate and incorporation in precipitated carbonate minerals removes proteinaceous DOM, but nearly equivalent concentrations of neutral and acidic forms of organic nitrogen in DOM remain in solution. Calcium carbonate precipitation during lime softening pretreatment of drinking water may have practical applications for removal of proteinaceous disinfection by-product precursors.

  13. Structural stability of coprecipitated natural organic matter and ferric iron under reducing conditions

    USGS Publications Warehouse

    Henneberry, Yumiko K.; Kraus, Tamara E.C.; Nico, Peter S.; Horwath, William R.

    2012-01-01

    The objective was to assess the interaction of Fe coprecipitated with dissolved organic matter (DOM) and its effect on Fe (hydr)oxide crystallinity and DOM retention under abiotic reducing conditions. A Fe-based coagulant was reacted with DOM from an agricultural drain and the resulting precipitate (floc) was exposed to S(-II) and Fe(II). Solution concentrations of Fe(II/III) and DOM were monitored, floc crystallinity was determined using X-ray diffraction, and the composition and distribution of functional groups were assessed using scanning transmission X-ray microscopy (STXM) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Results indicate coprecipitation of Fe(III) with DOM forms a non-crystalline floc that withstands crystallization regardless of change in pH, Fe:DOM ratio and type of reductant added. There was no evidence that exposure to reducing conditions led to release of DOM from the floc, indicating that coprecipitation with complex natural DOM in aquatic environments may stabilize Fe (hydr)oxides against crystallization upon reaction with reduced species and lead to long term sequestration of the DOM. STXM analysis identified spatially distinct regions with remarkable functional group purity, contrary to the model of DOM as a relatively uniform complex polymer lacking identifiable organic compounds. Polysaccharide-like OM was strongly and directly correlated with the presence of Fe but showed different Fe binding strength depending on the presence of carboxylic acid functional groups, whereas amide and aromatic functional groups were inversely correlated with Fe content.

  14. An innovative carbonate coprecipitation process for the removal of zinc and manganese from mining impacted waters

    USGS Publications Warehouse

    Sibrell, P.L.; Chambers, M.A.; Deaguero, A.L.; Wildeman, T.R.; Reisman, D.J.

    2007-01-01

    Although mine drainage is usually thought of as acidic, there are many cases where the water is of neutral pH, but still contains metal species that can be harmful to human or aquatic animal health, such as manganese (Mn) and zinc (Zn). Typical treatment of mine drainage waters involves pH adjustment, but this often results in excessive sludge formation and removal of nontoxic species such as magnesium and calcium. Theoretical consideration of the stability of metal carbonate species suggests that the target metals could be removed from solution by coprecipitation with calcium carbonate. The U.S. Geological Survey has developed a limestone-based process for remediation of acid mine drainage that increases calcium carbonate saturation. This treatment could then be coupled with carbonate coprecipitation as an innovative method for removal of toxic metals from circumneutral mine drainage waters. The new process was termed the carbonate coprecipitation (CCP) process. The CCP process was tested at the laboratory scale using a synthetic mine water containing 50 mg/L each of Mn and Zn. Best results showed over 95% removal of both Mn and Zn in less than 2 h of contact in a limestone channel. The process was then tested on a sample of water from the Palmerton zinc superfund site, near Palmerton, Pennsylvania, containing over 300 mg/L Zn and 60 mg/L Mn. Treatment of this water resulted in removal of over 95% of the Zn and 40% of the Mn in the limestone channel configuration. Because of the potential economic advantages of the CCP process, further research is recommended for refinement of the process for the Palmerton water and for application to other mining impacted waters as well. ?? Mary Ann Liebert, Inc.

  15. Phase transitions in coprecipitated NiO-WO/sub 3/ system in calcination, reduction, and sulfiding

    SciTech Connect

    Agievskii, D.A.; Pavlova, L.I.; Landau, M.V.; Kvashonkin, V.I.; Chukin, G.D.

    1986-04-01

    X-ray diffraction and electron microscopy have been used in an investigation of the shaping of phase composition and structure of a coprecipitated NiO-WO/sub 3/ system in calcination, reduction, and sulfiding. It has been shown that calcination, when it leads to the formation of crystalline NiWO/sub 4/, lowers the efficiency of reduction and sulfiding to a considerable degree. A step-temperature sulfiding operation, in comparison with isothermal sulfiding, gives a less ordered structure of the WS/sub 2/, with loose packing of the particles into agglomerates.

  16. Effect of sintering on structural and electrical properties of co-precipitated Mn-Zn ferrites

    NASA Astrophysics Data System (ADS)

    Mehmood, S.; Zahra, F.; Rehman, M. A.

    2016-08-01

    Mn-Zn ferrite is one of the important class of soft ferrites. These are famous for possessing high initial permeability. In the present work, we have studied the effect of sintering on Mn-Zn nano particles. The particles were synthesized using co-precipitation method. The structural characterization of the prepared sample after each sintering step were done by using XRD. The XRD analysis showed the spinel structure. The electrical properties were studied as a function of temperature. It was observed that dielectric constant, loss tangent and AC conductivity varies with respect to temperature. The prepared composition is useful in microwave devices.

  17. Synthesis of MgNb{sub 2}O{sub 6} by coprecipitation

    SciTech Connect

    Navale, S.C.; Gaikwad, A.B.; Ravi, V. . E-mail: ravi@ems.ncl.res.in

    2006-07-13

    A simple coprecipitation technique was used successfully to synthesize fine powders of MgNb{sub 2}O{sub 6} (MN) phase. An aqueous mixture of ammonium carbonate and ammonium hydroxide was used to precipitate Mg{sup 2+} and Nb{sup 5+} cations as carbonate and hydroxide respectively under basic conditions. This precipitate on heating at 750 deg. C produced MN powders. For comparison MN powders were prepared by the traditional solid state method. The phase content and the lattice parameters were studied by powder X-ray diffraction (XRD). Particle size and morphology of the particles were studied by scanning electron microscopy (SEM)

  18. Sorption and coprecipitation of copper to ferrihydrite and humic acid organomineral complexes and controls on copper availability.

    PubMed

    Seda, Neila N; Koenigsmark, Faye; Vadas, Timothy M

    2016-03-01

    Coprecipitation of Fe oxide and organic matter in redox dynamic sediments controls the net retention and form of Cu in the solid precipitates. In this study, coprecipitation and sorption of Cu with organomineral precipitation solids formed at different Fe:organic carbon (OC) ratios were compared for net Cu removal and extractability. As more humic acid was present during precipitation of Fe, TEM images indicated smaller Fe oxide particles formed within an organic matrix as expected. In coprecipitation reactions, as the ratio of Fe:OC decreased, more Cu was removed from solution at pH 5.5 and below. However, in sorption reactions, there was an inhibition of Cu removal at low OC concentrations. As the pH increased from 5.5 to 7 and as solution phase OC concentration increased, more Cu remained dissolved in both coprecipitation and sorption reactions. The addition of Ca(2+), glycine, histidine and citric acid or lowering the pH resulted in more extractable Cu from the coprecipitation compared with the sorption reactions. The variations in Cu extraction were likely due to a combination of a more amorphous structure in CPT products, and the relative abundance of available Fe oxide or OC binding sites. This has implications for the assumption of additivity in binding phases and for researchers conducting binding or exposure experiments.

  19. FRACTIONAL CRYSTALLIZATION LABORATORY TESTING FOR INCLUSION & COPRECIPITATION WITH ACTUAL TANK WASTE

    SciTech Connect

    WARRANT, R.W.

    2006-12-11

    Fractional crystallization is being considered as a pretreatment method to support supplemental treatment of retrieved single-shell tank (SST) saltcake waste at the Hanford Site. The goal of the fractional crystallization process is to optimize the separation of the radioactivity (radionuclides) from the saltcake waste and send it to the Waste Treatment and Immobilization Plant and send the bulk of the saltcake to the supplemental treatment plant (bulk vitrification). The primary factors that influence the separation efficiency are (1) solid/liquid separation efficiency, (2) contaminant inclusions, and (3) co-precipitation. This is a report of testing for factors (2) and (3) with actual tank waste samples. For the purposes of this report, contaminant inclusions are defined as the inclusion of supernatant, containing contaminating radionuclides, in a pocket within the precipitating saltcake crystals. Co-precipitation is defined as the simultaneous precipitation of a saltcake crystal with a contaminating radionuclide. These two factors were tested for various potential fractional crystallization product salts by spiking the composite tank waste samples (SST Early or SST Late, external letter CH2M-0600248, ''Preparation of Composite Tank Waste Samples for ME-21 Project'') with the desired target salt and then evaporating to precipitate that salt. SST Early represents the typical composition of dissolved saltcake early in the retrieval process, and SST Late represents the typical composition during the later stages of retrieval.

  20. The coprecipitation of Pu and other radionuclides with CaCO[sub 3

    SciTech Connect

    Meece, D.E.; Benninger, L.K. )

    1993-04-01

    The record of fallout plutonium concentrations in annual bands of corals is strikingly similar to the record of atmospheric deposition of [sup 90]Sr. This similarity implies that corals may incorporate Pu from seawater with a constant partition coefficient (constant discrimination). To investigate physicochemical aspects of Pu incorporation, the following have been coprecipitated with CaCO[sub 3] (calcite and aragonite): oxidized and reduced Pu; americium, thorium, and uranium as analogs to Pu oxidation states (III, IV, VI), respectively; and [sup 210]Pb as a particle-reactive nuclide which may be incorporated by corals with constant discrimination. Americium, thorium, and lead adsorb onto both calcite and aragonite, with more than 99% of the recovered activity found associated with the solids. Uranium exhibits a behavior consistent with lattice substitution. Partition coefficients for U in aragonite range from 1.8 to 9.8 and vary inversely with pH and/or rate of precipitation. The partition coefficient for U in calcite is less than 0.2 and may be as low as 0.046. Reduced Pu sorbs with 3 to 4% remaining in solution. Oxidized Pu may both sorb and coprecipitate. The coral record for Pb and U results primarily from biological, rather than physicochemical, effects; it is likely that the PU coral record also reflects biological discrimination. 50 refs., 4 figs., 5 tabs.

  1. Oxalate co-precipitation synthesis of calcium zirconate and calcium titanate powders.

    SciTech Connect

    Hernandez-Sanchez, Bernadette A.; Tuttle, Bruce Andrew

    2009-06-01

    Fine powders of calcium zirconate (CaZrO{sub 3}, CZ) and calcium titanate (CaTiO{sub 3}, CT) were synthesized using a nonaqueous oxalate co-precipitation route from Ca(NO{sub 3}){sub 2}{center_dot}4 H{sub 2}O and group(IV) n-butoxides (Ti(OBu{sup n}){sub 4} or Zr(OBu{sup n}){sub 4}). Several reaction conditions and batch sizes (2-35 g) were explored to determine their influence on final particle size, morphology, and phase. Characterization of the as-prepared oxalate precursors, oven dried oxalate precursors (60-90 C), and calcined powders (635-900 C) were analyzed with TGA/DTA, XRD, TEM, and SEM. Densification and sintering studies on pressed CZ pellets at 1375 and 1400 C were also performed. Through the developed oxalate co-precipitation route, densification temperatures for CZ were lowered by 125 C from the 1500 C firing temperature required for conventional mixed oxide powders. Low field electrical tests of the CZ pellets indicated excellent dielectric properties with dielectric constants of {approx}30 and a dissipation factor of 0.0004 were measured at 1 kHz.

  2. Immobilization of Hg(II) by Coprecipitation in Sulfate-Cement Systems

    PubMed Central

    2012-01-01

    Uptake and molecular speciation of dissolved Hg during formation of Al- or Fe-ettringite-type and high-pH phases were investigated in coprecipitation and sorption experiments of sulfate-cement treatments used for soil and sediment remediation. Ettringite and minor gypsum were identified by XRD as primary phases in Al systems, whereas gypsum and ferrihydrite were the main products in Hg–Fe precipitates. Characterization of Hg–Al solids by bulk Hg EXAFS, electron microprobe, and microfocused-XRF mapping indicated coordination of Hg by Cl ligands, multiple Hg and Cl backscattering atoms, and concentration of Hg as small particles. Thermodynamic predictions agreed with experimental observations for bulk phases, but Hg speciation indicated lack of equilibration with the final solution. Results suggest physical encapsulation of Hg as a polynuclear chloromercury(II) salt in ettringite as the primary immobilization mechanism. In Hg–Fe solids, structural characterization indicated Hg coordination by O atoms only and Fe backscattering atoms that is consistent with inner-sphere complexation of Hg(OH)20 coprecipitated with ferrihydrite. Precipitation of ferrihydrite removed Hg from solution, but the resulting solid was sufficiently hydrated to allow equilibration of sorbed Hg species with the aqueous solution. Electron microprobe XRF characterization of sorption samples with low Hg concentration reacted with cement and FeSO4 amendment indicated correlation of Hg and Fe, supporting the interpretation of Hg removal by precipitation of an Fe(III) oxide phase. PMID:22594782

  3. Co-precipitation of oppositely charged nanoparticles: the case of mixed ligand nanoparticles

    NASA Astrophysics Data System (ADS)

    Moglianetti, Mauro; Ponomarev, Evgeniy; Szybowski, Maxime; Stellacci, Francesco; Reguera, Javier

    2015-11-01

    Colloid stability is of high importance in a multitude of fields ranging from food science to biotechnology. There is strong interest in studying the stability of small particles (of a size of a few nanometres) with complex surface structures, that make them resemble the complexity of proteins and other natural biomolecules, in the presence of oppositely charged nanoparticles. While for nanoparticles with homogeneously charged surfaces an abrupt precipitation has been observed at the neutrality of charges, data are missing about the stability of nanoparticles when they have more complex surface structures, like the presence of hydrophobic patches. To study the role of these hydrophobic patches in the stability of nanoparticles a series of negatively charged nanoparticles has been synthesized with different ratios of hydrophobic content and with control on the structural distribution of the hydrophobic moiety, and then titrated with positively charged nanoparticles. For nanoparticles with patchy nanodomains, the influence of hydrophobic content was observed together with the influence of the size of the nanoparticles. By contrast, for nanoparticles with a uniform distribution of hydrophobic ligands, size changes and hydrophobic content did not play any role in co-precipitation behaviour. A comparison of these two sets of nanoparticles suggests that nanodomains present at the surfaces of nanoparticles are playing an important role in stability against co-precipitation.

  4. Determination of cadmium in spring water by graphite-furnace atomic absorption spectrometry after coprecipitation with ytterbium hydroxide.

    PubMed

    Atsumi, Kousuke; Minami, Tomoharu; Ueda, Joichi

    2005-06-01

    A coprecipitation method with ytterbium hydroxide was studied for the determination of cadmium in water samples by graphite-furnace atomic absorption spectrometry. Up to 40 ng of cadmium in water samples was quantitatively coprecipitated with ytterbium hydroxide at pH 8.0-11.2. The concentration factor was 100 fold. The coprecipitated cadmium was sensitively determined without any influence of ytterbium and the calibration curve was linear from 0.1 to 4 ng/mL of cadmium. The detection limit (signal/noise = 2) was 2.9 pg/mL in 100 mL of the initial sample solution. Twenty-nine diverse ions tested did not interfere with the determination in at least a 10000-fold mass ratio to cadmium. The proposed method was successfully applied to the determination of cadmium in spring water.

  5. Impedance response and dielectric relaxation in co-precipitation derived ferrite (Ni,Zn)Fe{sub 2}O{sub 4} ceramics

    SciTech Connect

    Chen, D. G.; Tang, X. G.; Liu, Q. X.; Jiang, Y. P.; Ma, C. B.; Li, R.

    2013-06-07

    Dielectric spectra and magnetization hysteresis loops were used to investigate the grain size effect with temperature on the electrical and magnetic response of co-precipitation derived spinel (Ni{sub 0.5}Zn{sub 0.5})Fe{sub 2}O{sub 4} (NZFO) ceramics. Remarkable dielectric relaxation phenomena of non-Debye type have been observed in each NZFO ceramics as confirmed by two kinds of Cole-Cole plots of the 1100 Degree-Sign C sintered samples, mainly due to the electron-hopping mechanism between n-type and p-type carriers and interfacial ion effect when applied an increase of temperature. The high and low response of grain and grain-boundary regions were determined by modeling the impedance experimental results on two equivalent RC circuits taking into account grain deep trap states. By employing the modified Arrhenius equation, activation energy values of different sintering temperatures were calculated and analyzed in combination with oxygen vacancy. In addition, the magnetization of various sintering temperature samples is dominated by cation distribution and surface effect in different particle ranges.

  6. Common Carrier Services.

    ERIC Educational Resources Information Center

    Federal Communications Commission, Washington, DC.

    This bulletin outlines the Federal Communications Commission's (FCC) responsibilities in regulating the interstate and foreign common carrier communication via electrical means. Also summarized are the history, technological development, and current capabilities and prospects of telegraph, wire telephone, radiotelephone, satellite communications,…

  7. Preconception Carrier Screening

    MedlinePlus

    ... What can the results of a carrier screening test tell me? A genetic counselor or your health care provider will use the results to calculate the ... the publisher. Related FAQs Genetic Disorders (FAQ094) Screening Tests for Birth Defects ... Education & Events Annual Meeting CME Overview CREOG ...

  8. A thermodynamic adsorption/entrapment model for selenium(IV) coprecipitation with calcite

    NASA Astrophysics Data System (ADS)

    Heberling, Frank; Vinograd, Victor L.; Polly, Robert; Gale, Julian D.; Heck, Stephanie; Rothe, Jörg; Bosbach, Dirk; Geckeis, Horst; Winkler, Björn

    2014-06-01

    Selenium is an environmentally relevant trace element, while the radioisotope 79Se is of particular concern in the context of nuclear waste disposal safety. Oxidized selenium species are relatively soluble and show only weak adsorption at common mineral surfaces. However, a possible sorption mechanism for selenium in the geosphere is the structural incorporation of selenium(IV) (selenite, SeO32-) into calcite (CaCO3). In this study we investigate the interactions between selenite and calcite by a series of experimental and computational methods with the aim to quantify selenite incorporation into calcite at standard conditions. We further seek to describe the thermodynamics of selenite-doped calcite, and selenite coprecipitation with calcite. The structure of the incorporated species is investigated using Se K-edge EXAFS (isotropic and polarization dependent) and results are compared to density functional theory (DFT) calculations. These investigations confirm structural incorporation of selenite into calcite by the substitution of carbonate for selenite, leading to the formation of a Ca(SeO3)X(CO3)(1-X) solid solution. Coprecipitation experiments at low supersaturation indicate a linear increase of the selenite to carbonate ratio in the solid with the increase of the selenite to carbonate ratio in the contact solution. This relationship can be described under the assumption of an ideal mixing between calcite and a virtual CaSeO3 endmember, whose standard Gibbs free energy (G0(CaSeO3_exp) = -953 ± 6 kJ/mol, log10(KSP(CaSeO3_exp)) = -6.7 ± 1.0) is defined by linear extrapolation of the excess free energy from the dilute Henry’s law domain to X(CaSeO3) = 1. In contrast to this experimental result, DFT and force field calculations predict the virtual bulk CaSeO3 endmember to be significantly less stable and more soluble: G0(CaSeO3 bulk) = -912 ± 10 kJ/mol and log10(KSP(CaSeO3_bulk)) = 0.5 ± 1.7. To explain this discrepancy we introduce a thermodynamic adsorption

  9. Sealed substrate carrier for electroplating

    DOEpatents

    Ganti, Kalyana Bhargava

    2012-07-17

    One embodiment relates to a substrate carrier for use in electroplating a plurality of substrates. The substrate carrier includes a non-conductive carrier body on which the substrates are held, and conductive lines are embedded within the carrier body. A conductive bus bar is embedded into a top side of the carrier body and is conductively coupled to the conductive lines. A thermoplastic overmold covers a portion of the bus bar, and there is a plastic-to-plastic bond between the thermoplastic overmold and the non-conductive carrier body. Other embodiments, aspects and features are also disclosed.

  10. Ubbelohde viscometer measurement of water-based Fe3O4 magnetic fluid prepared by coprecipitation

    NASA Astrophysics Data System (ADS)

    Gu, H.; Tang, X.; Hong, R. Y.; Feng, W. G.; Xie, H. D.; Chen, D. X.; Badami, D.

    2013-12-01

    Fe3O4 nanoparticles were prepared by co-precipitation and coated by sodium dodecyl benzene sulfonate (SDBS) to obtain water-based magnetic fluid. The viscosity of the magnetic fluid was measured using an Ubbelohde viscometer. The effects of magnetic particles volume fraction, surfactant mass fraction and temperature on the viscosity were studied. Experimental results showed that the magnetic fluid with low magnetic particle volume fraction behaved as a Newtonian fluid and the viscosity of the magnetic fluid increased with an increase of the suspended magnetic particles volume fraction. The experimental data was compared with the results of a theoretically derived equation. The viscosity of the magnetic fluid also increased with an increase in surfactant mass portion, while it decreased with increasing temperature. Moreover, the viscosity increased with increasing the magnetic field intensity. Increasing the temperature and the surfactant mass fraction weakened the influence of the magnetic field on the viscosity of the magnetic fluid.

  11. Preparation and Heat-Treatment of DWPF Simulants With and Without Co-Precipitated Noble Metals

    SciTech Connect

    Koopman, David C.:Eibling, Russel E

    2005-08-01

    The Savannah River National Laboratory is in the process of investigating factors suspected of impacting catalytic hydrogen generation in the Chemical Process Cell of the Defense Waste Processing Facility, DWPF. Noble metal catalyzed hydrogen generation in simulation work constrains the allowable acid addition operating window in DWPF. This constraint potentially impacts washing strategies during sludge batch preparation. It can also influence decisions related to the addition of secondary waste streams to a sludge batch. Noble metals have historically been added as trim chemicals to process simulations. The present study investigated the potential conservatism that might be present from adding the catalytic species as trim chemicals to the final sludge simulant versus co-precipitating the noble metals into the insoluble sludge solids matrix. Parallel preparations of two sludge simulants targeting the composition of Sludge Batch 3 were performed in order to evaluate the impact of the form of noble metals. Identical steps were used except that one simulant had dissolved palladium, rhodium, and ruthenium present during the precipitation of the insoluble solids. Noble metals were trimmed into the other stimulant prior to process tests. Portions of both sludge simulants were held at 97 C for about eight hours to qualitatively simulate the effects of long term storage on particle morphology and speciation. The simulants were used as feeds for Sludge Receipt and Adjustment Tank, SRAT, process simulations. The following conclusions were drawn from the simulant preparation work: (1) The first preparation of a waste slurry simulant with co-precipitated noble metals was successful, based on the data obtained. It appears that 99+% of the noble metals were retained in the simulant. (2) Better control of carbonate, hydroxide, and post-wash trim chemical additions is needed before the new method of simulant preparation will be as reproducible as the old method. (3) The two new

  12. Microstructure of Yttria-Doped Ceria as a Function of Oxalate Co-Precipitation Synthesis Conditions

    NASA Astrophysics Data System (ADS)

    Brissonneau, Laurent; Mathieu, Aurore; Tormos, Brigitte; Martin-Garin, Anna

    2016-06-01

    In sodium fast reactors (SFR), dissolved oxygen in sodium can be monitored via potentiometric sensors with an yttria-doped thoria electrolyte. Yttria-doped ceria (YDC) was chosen as a surrogate material to validate the process of such sensors. The material must exhibit high density and a fine grain microstructure to be resistant to the corrosion by liquid sodium and thermal shocks. Thus, the oxalic co-precipitation route was chosen to avoid milling steps that could bring impurity incorporation which is suspected to induce grain boundary corrosion in sodium. The powder and sintered pellets examination show that the synthesis conditions are of primary importance on the process yield, the oxalate powder microstructure and, eventually, on the ceramic density and microstructure. The impurity content was limited by controlling the synthesis, calcination, and sintering steps.

  13. Green and red luminescence in co-precipitation synthesized Pr:LuAG nanophosphor

    NASA Astrophysics Data System (ADS)

    Kumar, S. Arun; Kumar, K. Ashok; Gunaseelan, M.; Asokan, K.; Senthilselvan, J.

    2016-05-01

    Pr:LuAG nanophosphor is an effective candidate in magnetic resonance imaging coupled positron emission tomography (MRI-PET) for medical imaging and scintillator applications. LuAG:Pr (0.05, 0.15 mol%) nanoscale ceramic powders were synthesized by co-precipitation method using urea as precipitant. Effect of antisite defect on structure and luminescence behavior was investigated. Pr:LuAG nanoceramic powders are found crystallized in cubic structure by high temperature calcination at 1400 °C and it shows antisite defect. HR-SEM analysis revealed spherically shaped Pr:LuAG nanoceramic particulate powders with ˜100 nm size. By the excitation at 450 nm, Pr:LuAG nanophosphor exhibit green to red luminescence in the wavelength range of 520 to 680 nm, which is originated from multiplet transition of Pr3+ ions.

  14. Thermodynamic stability of CoOOH and its coprecipitation with manganese

    USGS Publications Warehouse

    Hem, J.D.; Roberson, C.E.; Lind, Carol J.

    1985-01-01

    A precipitate of cobalt oxyhydroxides formed by bubbling oxygen through a dilute solution of Co(NO3)2 held at pH 9.0 and 25??C was aged for 23 months in contact with the original solution, with access to atmospheric oxygen. Co3O4 and CoOOH were identified in the precipitate by X-ray diffraction. Chemical equilibria involving these solids were evaluated by measurements of solution pH and Co2+ activities and by redox potential measurements and gave a ??GcoOOH0 of -92.3 ?? 0.5 kcal/mole. This value and other thermodynamic data show relative feasibility of hypothetical reaction steps and changes in reaction paths during automated coprecipitation titrations and subsequent aging of a precipitate that finally contained ??MnOOH, MnO2 (birnessite) and CoOOH. ?? 1985.

  15. Synthesis of coprecipitated strontium hexaferrite nanoparticles in the presence of polyvinyl alcohol

    NASA Astrophysics Data System (ADS)

    Davoodi, A.; Hashemi, B.; Yousefi, M. H.

    2011-12-01

    Strontium hexaferrite (SrFe12O19) nanoparticles were synthesized by the chemical coprecipitation method and using polyvinyl alcohol (PVA) as a protective agent. The synthesized samples were characterized by differential thermal analysis, X-ray diffraction, scanning and transmission electron microscopy, particle size analyzer, sedimentation test and vibrating sample magnetometer. In the presence of PVA, the single-phase SrFe12O19 nanoparticles were obtained at low temperature of 650 °C. The average particle size of SrFe12O19 precursor was 15 nm, which increased to 61 nm after calcination at 650 °C. The magnetic measurements indicated that PVA decreased coercivity from 4711 to 3216 Oe with particle size reduction. The results showed that PVA as a protective agent could be effective in decreasing the particle size, calcination temperature and coercivity of SrFe12O19 nanoparticles.

  16. [Determination of trace calcium in pearl eye drops by coprecipitation atomic absorption spectrophotometry].

    PubMed

    Liang, Ai-hui; Jiang, Zhi-liang; Wang, Xiu-li

    2007-01-01

    The trace calcium in pearl eye drops was analyzed by atomic absorption spectrophotometry after the SrNO3-K2 CO3 co-precipitation. The absorbance at 422. 7 nm is linear with the calcium concentration in the range of 0. 0-20. 0 microg x mL(-1). The detection limit is 0. 06 microg x mL(-1) Ca. A new atomic absorption spectrophotometric method was proposed for the determination of calcium in pearl eye drops, with some advantages including high sensitivity, simplicity, rapidity and accuracy. The recovery is in the range of 97. 0%-98. 3%(n=5). The RSD is 0. 4%. It proved a good method for the determination of calcium in pearl eye drops.

  17. Structural characterization of FeVO4 synthesized by co-precipitation method

    NASA Astrophysics Data System (ADS)

    Bera, Ganesh; Sinha, Sourav; Rambabu, P.; Das, P.; Gupta, A. K.; Turpu, G. R.

    2016-05-01

    A Low temperature method for synthesizing triclinic FeVO4 nanoparticles is manifested through co-precipitation method. Three precursor materials taken for the synthesis are Iron Nitrate, Ammonium Metavanadate and NaOH along with DI water. The attained precipitate was dried at 100°C for overnight and calcined at different temperatures ranging from 400°C - 650°C. The achieved powdered materials are studied through X - ray diffraction and found to be in pure single phase of P-1 space group symmetry. The crystallite size measured through Scherrer's method is in found to be in the range of 40-60 nm. Raman spectroscopic studies were carried out at room temperature. Raman spectra is in agreement with the reported structural data of FeVO4.

  18. Influence of various surfactants on magnetic property of cobalt ferrite prepared by Co-precipitation technique

    NASA Astrophysics Data System (ADS)

    Solanki, Neha; Khatri, Hemal; Jotania, R. B.

    2016-05-01

    Cobalt Ferrite (CoFe2O4) particles were synthesised using a Co-precipitation method. Influence of three different surfactants i.e. (1) Cationic - CTAB (Cetyl Tri-Methyl Ammonium Bromide), (2) Anionic - SDBS (Sodium Dodecyl Benzene Sulphonate) and (3) Nonionic - Triton X-100, on magnetic property of Cobalt Ferrite were investigated. Magnetic property of Cobalt ferrite powder was studied at room temperature using Vibrating Sample Measurements (VSM) technique under an applied magnetic field of 15kOe. The results show maximum value of saturation magnetization - Ms (81.87 emu/g) for the sample synthesised without surfactant and Coercivity value found maximum (2086 kOe) for the sample synthesized in presence of surfactant SDBS.

  19. Yarn carrier with clutch

    NASA Technical Reports Server (NTRS)

    Doyne, Richard A. (Inventor); Benson, Rio H. (Inventor); El-Shiekh, Aly (Inventor)

    1994-01-01

    A yarn carrier apparatus particularly suited for use in braiding machinery or the like due to its capability of continuous yarn feeding and retraction of long lengths of yarn. The yarn carrier apparatus comprises a yarn supply spool which is rotatably mounted within the housing, a spring motor also mounted within the housing and operatively connected to the yarn supply spool through a mechanical transmission assembly which is adapted to multiply rotational movement between the first element of the gear assembly operatively connected to the spring motor and the final element of the gear assembly operatively connected to the yarn supply spool. The spring motor is adapted to tension the yarn during both feeding and retraction thereof, and it is further adapted to periodically rotatably slip within the housing and partially unwind so as to allow for continuous withdrawal of a long length of yarn without the spring motor becoming fully wound and preventing further yarn retraction.

  20. Engineered microparticles based on drug-polymer coprecipitates for ocular-controlled delivery of Ciprofloxacin: influence of technological parameters.

    PubMed

    Gavini, Elisabetta; Bonferoni, Maria Cristina; Rassu, Giovanna; Sandri, Giuseppina; Rossi, Silvia; Salis, Andrea; Porcu, Elena Piera; Giunchedi, Paolo

    2016-01-01

    Ciprofloxacin is a drug active against a broad spectrum of aerobic Gram-positive and Gram-negative bacteria, for the therapy of ocular infections. It requires frequent administrations owing to rapid ocular clearance and it is a good candidate for ocular controlled release formulations. The preparation of such drug release systems is still a challenge. Ionic interactions between ciprofloxacin and the polyelectrolytes chondroitin sulfate or lambda carrageenan result in coprecipitates that can act as microparticulate controlled release systems from which the drug is released after being displaced by the medium's ions. In some formulations, Carbopol was added to improve the mucoadhesive properties. The aim of this research was the study of the influence of the technological parameters of the preparation method of coprecipitates on their particle size, with the goal of achieving particles engineered with a size suitable for the ocular administration. Technological parameters taken into account were: concentration of drug and polymer solutions utilized for the preparation of interaction products, possible use of surfactants (kind and concentration), temperature of the solutions and stirring during the process of preparation of the coprecipitates. Preliminary stability study tests were carried out to further characterize the leader formulation. Particle size in suspensions for ocular drug delivery is a critical parameter influencing the quality of the formulation. The results obtained from this study show that chondroitin sulfate coprecipitates present the best characteristics in terms of particle size suitable for ocular administration. A further improvement of the particle size characteristics has been obtained with the addition of surfactants.

  1. Determination of some trace elements in food and soil samples by atomic absorption spectrometry after coprecipitation with holmium hydroxide.

    PubMed

    Saracoglu, Sibel; Soylak, Mustafa; Cabuk, Dilek; Topalak, Zeynep; Karagozlu, Yasemin

    2012-01-01

    The determination of trace elements in food and soil samples by atomic absorption spectrometry was investigated. A coprecipitation procedure with holmium hydroxide was used for separation-preconcentration of trace elements. Trace amounts of copper(II), manganese(II), cobalt(II), nickel(ll), chromium(lll), iron(Ill), cadmium(ll), and lead(ll) ions were coprecipitated with holmium hydroxide in 2.0 M NaOH medium. The optimum conditions for the coprecipitation process were investigated for several commonly tested experimental parameters, such as amount of coprecipitant, effect of standing time, centrifugation rate and time, and sample volume. The precision, based on replicate analysis, was lower than 10% for the analytes. In order to verify the accuracy of the method, the certified reference materials BCR 141 R calcareous loam soil and CRM 025-050 soil were analyzed. The procedure was successfully applied for separation and preconcentration of the investigated ions in various food and soil samples. An amount of the solid samples was decomposed with 15 mL concentrated hydrochloric acid-concentrated nitric acid (3 + 1). The preconcentration procedure was then applied to the final solutions. The concentration of trace elements in samples was determined by atomic absorption spectrometry.

  2. Properties and reactivity of Fe-organic matter associations formed by coprecipitation versus adsorption: Clues from arsenate batch adsorption

    NASA Astrophysics Data System (ADS)

    Mikutta, Robert; Lorenz, Dennis; Guggenberger, Georg; Haumaier, Ludwig; Freund, Anja

    2014-11-01

    Ferric oxyhydroxides play an important role in controlling the bioavailability of oxyanions such as arsenate and phosphate in soil. Despite this, little is known about the properties and reactivity of Fe(III)-organic matter phases derived from adsorption (reaction of organic matter (OM) to post-synthesis Fe oxide) versus coprecipitation (formation of Fe oxides in presence of OM). Coprecipitates and adsorption complexes were synthesized at pH 4 using two natural organic matter (NOM) types extracted from forest floor layers (Oi and Oa horizon) of a Haplic Podzol. Iron(III) coprecipitates were formed at initial molar metal-to-carbon (M/C) ratios of 1.0 and 0.1 and an aluminum (Al)-to-Fe(III) ratio of 0.2. Sample properties were studied by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), N2 gas adsorption, dynamic light scattering, and electrophoretic mobility measurements. Arsenic [As(V)] adsorption to Fe-OM phases was studied in batch experiments (168 h, pH 4, 100 μM As). The organic carbon (OC) contents of the coprecipitates (82-339 mg g-1) were higher than those of adsorption complexes (31 and 36 mg g-1), leading to pronounced variations in specific surface area (9-300 m2 g-1), average pore radii (1-9 nm), and total pore volumes (11-374 mm3 g-1) but being independent of the NOM type or the presence of Al. The occlusion of Fe solids by OM (XPS surface concentrations: 60-82 atom% C) caused comparable pHPZC (1.5-2) of adsorption complexes and coprecipitates. The synthesis conditions resulted in different Fe-OM association modes: Fe oxide particles in 'M/C 0.1' coprecipitates covered to a larger extent the outermost aggregate surfaces, for some 'M/C 1.0' coprecipitates OM effectively enveloped the Fe oxides, while OM in the adsorption complexes primarily covered the outer aggregate surfaces. Despite of their larger OC contents, adsorption of As(V) was fastest to coprecipitates formed at low Fe availability (M/C 0.1) and facilitated by desorption of weakly

  3. Structure and composition of Fe-OM co-precipitates that form in soil-derived solutions

    NASA Astrophysics Data System (ADS)

    Fritzsche, Andreas; Schröder, Christian; Wieczorek, Arkadiusz K.; Händel, Matthias; Ritschel, Thomas; Totsche, Kai U.

    2015-11-01

    Iron oxides represent a substantial fraction of secondary minerals and particularly affect the reactive properties of natural systems in which they formed, e.g. in soils and sediments. Yet, it is still obscure how transient conditions in the solution will affect the properties of in situ precipitated Fe oxides. Transient compositions, i.e. compositions that change with time, arise due to predominant non-equilibrium states in natural systems, e.g. between liquid and solid phases in soils. In this study, we characterize Fe-OM co-precipitates that formed in pH-neutral exfiltrates from anoxic topsoils under transient conditions. We applied soil column outflow experiments, in which Fe2+ was discharged with the effluent from anoxic soil and subsequently oxidized in the effluent due to contact with air. Our study features three novel aspects being unconsidered so far: (i) the transient composition of soil-derived solutions, (ii) that pedogenic Fe oxides instead of Fe salts serve as major source for Fe2+ in soil solution and (iii) the presence of exclusively soil-derived organic and inorganic compounds during precipitation. The experiments were carried out with two topsoil materials that differed in composition, texture and land use. Derived from Mössbauer spectroscopy, broad distributions in quadrupole splittings (0-2 mm s-1) and magnetic hyperfine fields (35-53 T) indicated the presence of low-crystalline ferrihydrite and even lower crystalline Fe phases in all Fe-OM co-precipitates. There was no unequivocal evidence for other Fe oxides, i.e. lepidocrocite and (nano)goethite. The Fe-OM co-precipitates contained inorganic (P, sulfate, silicate, Al, As) and organic compounds (proteins, polysaccharides), which were concurrently discharged from the soils. Their content in the Fe-OM co-precipitates was controlled by their respective concentration in the soil-derived solution. On a molar basis, OC and Fe were the main components in the Fe-OM co-precipitates (OC/Fe ratio = 0

  4. Influence of Coprecipitated Organic Matter on Fe2+(aq) -Catalyzed Transformation of Ferrihydrite: Implications for Carbon Dynamics

    SciTech Connect

    Chen, Chunmei; Kukkadapu, Ravi K.; Sparks, Donald L.

    2015-08-10

    The poorly crystalline Fe(III) hydroxide ferrihydrite is an important sink for organic matter (OM), nutrients and contaminants in soils and sediments. Aqueous Fe(II) is known to catalyze the transformation of ferrihydrite to more crystalline and thus less reactive phases. While coprecipitation of OM with ferrihydrite could be a common process in many environments due to changes in pH, redox potential or ionic strength, little is known about the impacts of coprecipitated OM on Fe(II)-catalyzed ferrihydrite transformation and its consequences for C dynamics. Accordingly, we explored the extent and pathways of Fe(II)-induced transformation of OM-ferrihydrite coprecipitates and subsequent C mobility. Mössbauer spectroscopic results indicated that the coprecipitated OM within ferrihydrite weakened the inter-particle magnetic interactions and decreased average particle size. The coprecipitated OM resulted in diminished Fe(II)-induced ferrihydrite transformation and thus preservation of ferrihydrite. The secondary mineral profiles upon Fe(II) reaction with ferrihydrite were a function of OM content and Fe(II) concentration. At low Fe(II) levels, OM completely inhibited goethite formation and stimulated lepidocrocite formation. At high Fe(II) levels, whereas goethite was formed in the presence of OM, OM reduced the amount of goethite and magnetite formation and increased the formation of lepidocrcocite. The solid-phase C content remained unchanged after reaction, while OM desorpability by H2PO4- was enhanced following reaction of OM-ferrihydrites with aqueous Fe(II). These findings provide insights into the reactivity of natural ferrihydrite containing OM in soils and sediments and the subsequent impact on mineral evolution and C dynamics.

  5. Maintainable substrate carrier for electroplating

    DOEpatents

    Chen, Chen-An; Abas, Emmanuel Chua; Divino, Edmundo Anida; Ermita, Jake Randal G.; Capulong, Jose Francisco S.; Castillo, Arnold Villamor; Ma, Diana Xiaobing

    2016-08-02

    One embodiment relates to a substrate carrier for use in electroplating a plurality of substrates. The carrier includes a non-conductive carrier body on which the substrates are placed and conductive lines embedded within the carrier body. A plurality of conductive clip attachment parts are attached in a permanent manner to the conductive lines embedded within the carrier body. A plurality of contact clips are attached in a removable manner to the clip attachment parts. The contact clips hold the substrates in place and conductively connecting the substrates with the conductive lines. Other embodiments, aspects and features are also disclosed.

  6. Maintainable substrate carrier for electroplating

    DOEpatents

    Chen, Chen-An; Abas, Emmanuel Chua; Divino, Edmundo Anida; Ermita, Jake Randal G.; Capulong, Jose Francisco S.; Castillo, Arnold Villamor; Ma; Diana Xiaobing

    2012-07-17

    One embodiment relates to a substrate carrier for use in electroplating a plurality of substrates. The carrier includes a non-conductive carrier body on which the substrates are placed and conductive lines embedded within the carrier body. A plurality of conductive clip attachment parts are attached in a permanent manner to the conductive lines embedded within the carrier body. A plurality of contact clips are attached in a removable manner to the clip attachment parts. The contact clips hold the substrates in place and conductively connecting the substrates with the conductive lines. Other embodiments, aspects and features are also disclosed.

  7. 49 CFR 369.2 - Classification of carriers-motor carriers of property, household goods carriers, and dual...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... contract motor carriers of property are grouped into the following three classes: Class I. Carriers having... applying the revenue deflator formula in Note A. Class II. Carriers having annual carrier operating... applying the revenue deflator formula in Note A. Class III. Carriers having annual carrier...

  8. Processing, structure and magnetic properties correlation in co-precipitated Ca-ferrite

    NASA Astrophysics Data System (ADS)

    Abasht, Behzad; Beitollahi, Ali; Mirkazemi, Seyyed Mohammad

    2016-12-01

    La-substituted hexagonal calcium ferrite, Ca1-XLaXFe12O19 (x varies from 0 to 0.6 with the step of 0.2), was synthesized by applying co-precipitation method, in which the molar ratio of Fe3+/(Ca2++La2+) was 11. The ferrite precursors were prepared from aqueous solution of calcium nitrate, ferric nitrate and lanthanum nitrate by co-precipitation of calcium, iron and lanthanum ions by using an aqueous base of sodium hydroxide (1.5 M) at the pH of 14 and at room temperature. These precursors were calcinated with different amount of La at different temperature of 700, 1100 and 1200 °C for constant calcination time of 1 h in a static air atmosphere. Some tests such as simultaneous thermal analysis (STA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) were carried out to investigate the thermal behavior, crystallographic properties, morphology and magnetic properties of the precursor powders which were calcinated at different temperatures. The powder XRD patterns of samples which consisted of La as dopant and were calcinated at 1200 °C for 1 h, indicates the formation of calcium hexaferrite and also α-Fe2O3 besides Magnetoplumbite-phase (M-phase). However, the results showed that CaFe4O7 and α-Fe2O3 phases were formed in the sample with the same condition but without using any dopant. The results of SEM showed that the calcium hexaferrite particle were regular hexagonal platelets with the size range of 1-2 μm. The magnetic properties such as maximum magnetization (MMax), remanent magnetization (Mr) and coercivity (Hc) were measured from the hysteresis loops. Low values of coercive field (16.3 kA m-1) and maximum magnetization (50.6 A m2 kg-1) were obtained from calcium hexaferrite particle in optimum amount of La (X=0.4) which calcinated at the temperature of 1200 °C.

  9. Eu(3+)-doped gadolinium oxide nanoparticles synthesized by chemical coprecipitation predicted by thermodynamic modeling.

    PubMed

    Hong, Seung Pyo; Kang, Seung Hee; Kim, Do Kyung; Kang, Bo Sun

    2014-11-01

    Thermodynamic modeling of the Gd(3+)-Eu(3+)-O(2-)-CO3(2-)-Cl- system has been adopted as a rational approach to establish routes to the better synthesis conditions for pure phase Eu(3+)-doped Gd2O3 nanoparticles. Quantitative analyses of the different reaction equilibria involved in the coprecipitation of Gd2(CO3)3 and Eu2(CO3)3 x 3H2O from aqueous solutions have been used to determine the optimum synthesis conditions. The characterization and photoluminescence spectra of Gd2O3 nanoparticles doped with Eu3+ activator ions at the concentrations of 1, 2, 3, 4 and 5 mol% synthesized by urea-based homogeneous coprecipitation are presented. The surface of the as-prepared mixture of Gd2(CO3)3 and Eu2(CO3)3 x 3H2O particles are coated with silica to avoid the agglomeration followed by annealing the carbonate precursors at 800 degrees C for 3 hours. Subsequently, the silica shell is removed with an alkali solution resulting in well-crystallized Eu(3+)-doped Gd2O3 nanoparticles. X-ray diffraction (XRD) results show that all the diffraction peaks are well indexed to the cubic Gd2O3 with high crystallinity. The photoluminescence spectra exhibit a characteristic f-f transition band that corresponds to Eu3+. The sharp red emission at 616 nm corresponds to the transition identified as 5D0 __7F2. Both the emission intensity at 616 nm and asymmetry factor of [I(5D0 --> 7F2)/I(5D0 --> 7F1)] exhibit clearly Eu(3+)-doping concentration-dependent luminescence behaviors. The rather fast decay time is closely correlated to the proper occupation of the Eu3+ activator ions in the C2 sites of the Gd2O3 cage, resulting in strong dependence on small changes of the total electric density and defect density. Thus, the best concentration of Eu3+ activator ions for the maximum brightness are the 3 mol% Eu(3+)-doped Gd2O3 at 5D0 --> 7F2 because it shows the longest decay time and more luminescent intensity than the other doping concentrations.

  10. Synthesis of talc/Fe3O4 magnetic nanocomposites using chemical co-precipitation method

    PubMed Central

    Kalantari, Katayoon; Ahmad, Mansor Bin; Shameli, Kamyar; Khandanlou, Roshanak

    2013-01-01

    The aim of this research was to synthesize and develop a new method for the preparation of iron oxide (Fe3O4) nanoparticles on talc layers using an environmentally friendly process. The Fe3O4 magnetic nanoparticles were synthesized using the chemical co-precipitation method on the exterior surface layer of talc mineral as a solid substrate. Ferric chloride, ferrous chloride, and sodium hydroxide were used as the Fe3O4 precursor and reducing agent in talc. The talc was suspended in deionized water, and then ferrous and ferric ions were added to this solution and stirred. After the absorption of ions on the exterior surface of talc layers, the ions were reduced with sodium hydroxide. The reaction was carried out under a nonoxidizing oxygen-free environment. There were not many changes in the interlamellar space limits (d-spacing = 0.94−0.93 nm); therefore, Fe3O4 nanoparticles formed on the exterior surface of talc, with an average size of 1.95–2.59 nm in diameter. Nanoparticles were characterized using different methods, including powder X-ray diffraction, transmission electron microscopy, emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. These talc/Fe3O4 nanocomposites may have potential applications in the chemical and biological industries. PMID:23696700

  11. Functionalization of emissive conjugated polymer nanoparticles by coprecipitation: consequences for particle photophysics and colloidal properties

    NASA Astrophysics Data System (ADS)

    Singh, Amita; Bezuidenhout, Michael; Walsh, Nichola; Beirne, Jason; Felletti, Riccardo; Wang, Suxiao; Fitzgerald, Kathleen T.; Gallagher, William M.; Kiely, Patrick; Redmond, Gareth

    2016-07-01

    The functionalization of polyfluorene (PFO) nanoparticles by coprecipitation of the conjugated polymer with an amphiphilic comb polymer, consisting of a hydrophobic polystyrene backbone with hydrophilic, carboxylic acid-terminated polyethylene oxide side-chains (PS-PEG-COOH), is investigated. The comb polymer affects the properties of the formed hybrid nanoparticles. Non-functionalized particles are typically larger (28 nm) than functionalized ones (20 nm); peak molar extinction coefficients are found to differ in a similar trend. Zeta potentials are negative, consistent with negative surface charge on PFO particles due to chemical defect formation, with additional charge on functionalized particles due to the pendant carboxylic acid groups. Emission quantum yields of functionalized particles are typically larger, consistent with lower efficiency of energy transfer to quenchers in smaller particles and weaker PFO interchain interactions due to chain dilution. The trend in per-particle fluorescence brightness values, as confirmed by single particle fluorescence imaging, reflects the nanoparticle extinction coefficients. Photostability studies on aqueous dispersions of hybrid particles indicate mild photobrightening under continuous illumination while PFO particles exhibit slow exponential emission decay. Functionalized particles are also resistant to aggregation during exposure to adenocarcinoma cells. Generally, the hybrid particles exhibit more favorable time-, pH- and medium-dependent stabilities, likely due to steric and electrostatic stabilization by PEG-carboxylic acid functionalities. Overall, the functionalized particles exhibit attractive properties: Reasonably small size, tight size distribution, high absorption cross section, radiative rate and emission quantum yield, excellent brightness and photostability, and good colloidal stability.

  12. Structural Characterization of Spinel Zinc Aluminate Nanoparticles Prepared By Coprecipitation Method

    NASA Astrophysics Data System (ADS)

    Sunder, Shyam; Rohilla, Sunil; Kumar, Sushil; Aghamkar, Praveen

    2011-12-01

    Zinc aluminate is well known wide bandgap semiconductor with cubic spinel structure and transparent for wavelength greater than 320 nm. Therefore, ZnAl2O4 can be used for ultraviolet photoelectronic devices. Furthermore, spinel zinc aluminate is useful in many reactions as catalytic support. Moreover, zinc aluminate can be used as second phase in glaze layer of white ceramics to improve wear resistance and to preserve whiteness. In present study cubic spinel zinc aluminate nanoparticles have been synthesized from aqueous solution of Zn(NO3)2.6H2O (0.1 M) and Al(NO3)2.9H2O (0.2 M) using chemical coprecipitation technique. Ammonium hydroxide was used as precipitating agent and pH was maintained between 8 to 9. The precipitated slurry was filtered and washed several times with deionized double distilled water and dried at 110 °C. The fine powder was annealed at different temperatures from 600 °C to 900 °C for 4h in temperature controlled furnace. Structural characterization of annealed samples was carried out via X-ray Diffraction (XRD), and Fourier Transform Infrared spectroscopy (FTIR). XRD patterns reveal that zinc aluminate samples were cubic spinel nanoparticles and grain size determined by Debye-Scherrer formula is from 5 to 16 nm.

  13. Functionalization of emissive conjugated polymer nanoparticles by coprecipitation: consequences for particle photophysics and colloidal properties.

    PubMed

    Singh, Amita; Bezuidenhout, Michael; Walsh, Nichola; Beirne, Jason; Felletti, Riccardo; Wang, Suxiao; Fitzgerald, Kathleen T; Gallagher, William M; Kiely, Patrick; Redmond, Gareth

    2016-07-29

    The functionalization of polyfluorene (PFO) nanoparticles by coprecipitation of the conjugated polymer with an amphiphilic comb polymer, consisting of a hydrophobic polystyrene backbone with hydrophilic, carboxylic acid-terminated polyethylene oxide side-chains (PS-PEG-COOH), is investigated. The comb polymer affects the properties of the formed hybrid nanoparticles. Non-functionalized particles are typically larger (28 nm) than functionalized ones (20 nm); peak molar extinction coefficients are found to differ in a similar trend. Zeta potentials are negative, consistent with negative surface charge on PFO particles due to chemical defect formation, with additional charge on functionalized particles due to the pendant carboxylic acid groups. Emission quantum yields of functionalized particles are typically larger, consistent with lower efficiency of energy transfer to quenchers in smaller particles and weaker PFO interchain interactions due to chain dilution. The trend in per-particle fluorescence brightness values, as confirmed by single particle fluorescence imaging, reflects the nanoparticle extinction coefficients. Photostability studies on aqueous dispersions of hybrid particles indicate mild photobrightening under continuous illumination while PFO particles exhibit slow exponential emission decay. Functionalized particles are also resistant to aggregation during exposure to adenocarcinoma cells. Generally, the hybrid particles exhibit more favorable time-, pH- and medium-dependent stabilities, likely due to steric and electrostatic stabilization by PEG-carboxylic acid functionalities. Overall, the functionalized particles exhibit attractive properties: Reasonably small size, tight size distribution, high absorption cross section, radiative rate and emission quantum yield, excellent brightness and photostability, and good colloidal stability. PMID:27306338

  14. Aqueous Co-precipitation of Pd-doped Cerium Oxide Nanoparticles: Chemistry Structure and Particle Growth

    SciTech Connect

    Liang H.; Zhang L.; Raitano J.M.; He G.; Akey A.J.; Herman I.P.; Chan S.-W.

    2012-01-01

    Nanoparticles of palladium-doped cerium oxide (Pd-CeO{sub 2}) have been prepared by aqueous co-precipitation resulting in a single phase cubic structure after calcination according to X-ray diffraction (XRD). Inhomogeneous strain, calculated using the Williamson-Hall method, was found to increase with palladium content, and the lattice contracts slightly, relative to nano-cerium oxide, as palladium content is increased. Moreover, high resolution transmission electron microscopy reveals some instances of defective microstructure. These factors combined imply that palladium is in solid solution with CeO{sub 2} in these nanoparticles, but palladium (II) oxide (PdO) peaks in the Raman spectra indicate that solid solution formation is partial and that highly dispersed PdO is present as well as the solid solution. Nevertheless, the addition of palladium to the CeO{sub 2} lattice inhibits the growth of the 6% Pd-CeO{sub 2} particles compared to pure CeO{sub 2} between 600 and 850 C. Activation energies for grain growth of 54 {+-} 7 and 79 {+-} 8 kJ/mol were determined for 6% Pd-CeO{sub 2} and pure CeO{sub 2}, respectively, along with pre-exponential Arrhenius factors of 10 for the doped sample and 600 for pure cerium oxide.

  15. Functionalization of emissive conjugated polymer nanoparticles by coprecipitation: consequences for particle photophysics and colloidal properties.

    PubMed

    Singh, Amita; Bezuidenhout, Michael; Walsh, Nichola; Beirne, Jason; Felletti, Riccardo; Wang, Suxiao; Fitzgerald, Kathleen T; Gallagher, William M; Kiely, Patrick; Redmond, Gareth

    2016-07-29

    The functionalization of polyfluorene (PFO) nanoparticles by coprecipitation of the conjugated polymer with an amphiphilic comb polymer, consisting of a hydrophobic polystyrene backbone with hydrophilic, carboxylic acid-terminated polyethylene oxide side-chains (PS-PEG-COOH), is investigated. The comb polymer affects the properties of the formed hybrid nanoparticles. Non-functionalized particles are typically larger (28 nm) than functionalized ones (20 nm); peak molar extinction coefficients are found to differ in a similar trend. Zeta potentials are negative, consistent with negative surface charge on PFO particles due to chemical defect formation, with additional charge on functionalized particles due to the pendant carboxylic acid groups. Emission quantum yields of functionalized particles are typically larger, consistent with lower efficiency of energy transfer to quenchers in smaller particles and weaker PFO interchain interactions due to chain dilution. The trend in per-particle fluorescence brightness values, as confirmed by single particle fluorescence imaging, reflects the nanoparticle extinction coefficients. Photostability studies on aqueous dispersions of hybrid particles indicate mild photobrightening under continuous illumination while PFO particles exhibit slow exponential emission decay. Functionalized particles are also resistant to aggregation during exposure to adenocarcinoma cells. Generally, the hybrid particles exhibit more favorable time-, pH- and medium-dependent stabilities, likely due to steric and electrostatic stabilization by PEG-carboxylic acid functionalities. Overall, the functionalized particles exhibit attractive properties: Reasonably small size, tight size distribution, high absorption cross section, radiative rate and emission quantum yield, excellent brightness and photostability, and good colloidal stability.

  16. Synthesis of strontium hexaferrite nanoparticles prepared using co-precipitation method and microemulsion processing

    NASA Astrophysics Data System (ADS)

    Drmota, A.; Žnidaršič, A.; Košak, A.

    2010-01-01

    Strontium hexaferrite (SrFe12O19) nanoparticles have been prepared with co-precipitation in aqueous solutions and precipitation in microemulsion system water/SDS/n-butanol/cyclohexane, using iron and strontium nitrates in different molar rations as a starting materials. The mixed Sr2+, Fe3+ hydroxide precursors obtained during the reaction between corresponding metal nitrates and tetramethylammonium hydroxide (TMAH), which served as a precipitating reagent, were calcined in a wide temperature range, from 350 °C to 1000 °C in a static air atmosphere. The influence of the Sr2+/Fe3+ molar ratio and the calcination temperature to the chemistry of the product formation, its crystallite size, morphology and magnetic properties were investigated. It was found that the formation of single phase SrFe12O19 with relatively high specific magnetization (54 Am2/kg) was achieved at the Sr2+/Fe3+ molar ration of 6.4 and calcination at 800 °C for 3h with heating/cooling rate 5 °C/min. The prepared powders were characterized using X-ray diffractometry (XRD) and specific surface area measurements (BET). The specific magnetization (DSM-10, magneto-susceptometer) of the prepared samples was measured.

  17. Structural characterization of malachite-like coprecipitated precursors of binary CuO-ZnO catalysts

    SciTech Connect

    Porta, P.; De Rossi, S.; Ferraris, G.; Lo Jacono, M.; Minelli, G.; Moretti, G.

    1988-02-01

    Copper and zinc hydroxycarbonates with Cu/Zn atomic ratios of 100/0, 92/8, 85/15, 77/23, 67/33, and 50/50 were prepared by the coprecipitation method. The samples with the ratios 100/0, 92/8 and 85/15 were monophasic with the monoclinic P2/sub 1//a malachite structure, whereas the richer zinc samples contained in addition to the malachite phase the orthorhombic B22/sub 1/2 aurichalcite, whose concentration was very low in the 77/23 specimen but increased continuously with zinc content. The amount of aurichalcite in the biphasic powders has been estimated by means of quantitative X-ray diffraction and differential thermal analysis. With only those X-ray reflections belonging to the malachite structure taken into account, the unit cell constants for all the solid solution hydroxycarbonates have been determined, showing that as a whole the cell volume of malachite decreases continuously with increasing zinc content. This result is related, as shown also by DTA measurements and thermochemical literature data, to an increasing stability of compounds richer in zinc, to increasing covalent effects, and/or to less octahedral site distortion around the metal atoms when zinc substitutes for Cu/sup 2 +/ ions in the malachite lattice. Magnetic susceptibility and thermogravimetric measurements together with diffuse reflectance spectra are also presented and discussed.

  18. Formation of electroactive colloids via in situ coprecipitation under electric field: erbium chloride alkaline aqueous pseudocapacitor.

    PubMed

    Chen, Kunfeng; Xue, Dongfeng

    2014-09-15

    For the first time, a new ErCl3 alkaline aqueous pseudocapacitor system was demonstrated by designing commercial ErCl3 salt electrode in alkaline aqueous electrolyte, where the materials synthesis and subsequently integrating into practical electrode structures occur at the same spatial and temporal scale. Highly electroactive ErOOH colloids were in-situ crystallized via electric field assisted chemical coprecipitation of ErCl3 in KOH aqueous electrolyte. These electroactive ErOOH colloids absorbed by carbon black and PVDF matrix were highly redox-reactive with higher cation utilization ratio of 86 % and specific capacitance values of 1811F/g, exceeding the one-electron redox theoretical capacitance (Er(3+)↔Er(2+)). We believe that additional two-electron (Er(2+)↔Er) or three-electron (Er(3+)↔Er) reactions can occur in our designed ErCl3 alkaline aqueous pseudocapacitor system. The specific electrode configuration with ErOOH colloids grown among the carbon black/PVDF matrix can create short ion diffusion and electron transfer length to enable the fast and reversible Faradaic reactions. This work shows promising for finding high-performance electrical energy storage systems via designing the colloidal state of electroactive cations with the utilization of in-situ crystallization route.

  19. Automatized and desktop AC-susceptometer for the in situ and real time monitoring of magnetic nanoparticles' synthesis by coprecipitation.

    PubMed

    Fernández-García, M P; Teixeira, J M; Machado, P; Oliveira, M R F F; Maia, J M; Pereira, C; Pereira, A M; Freire, C; Araujo, J P

    2015-04-01

    The main purpose of this work was to design, develop, and construct a simple desktop AC susceptometer to monitor in situ and in real time the coprecipitation synthesis of magnetic nanoparticles. The design incorporates one pair of identical pick-up sensing coils and one pair of Helmholtz coils. The picked up signal is detected by a lock-in SR850 amplifier that measures the in- and out-of-phase signals. The apparatus also includes a stirrer with 45°-angle blades to promote the fast homogenization of the reaction mixture. Our susceptometer has been successfully used to monitor the coprecipitation reaction for the synthesis of iron oxide nanoparticles. PMID:25933868

  20. Personnel emergency carrier vehicle

    NASA Technical Reports Server (NTRS)

    Owens, Lester J. (Inventor); Fedor, Otto H. (Inventor)

    1987-01-01

    A personnel emergency carrier vehicle is disclosed which includes a vehicle frame supported on steerable front wheels and driven rear wheels. A supply of breathing air is connected to quick connect face mask coupling and umbilical cord couplings for supplying breathing air to an injured worker or attendant either with or without a self-contained atmospheric protection suit for protection against hazardous gases at an accident site. A non-sparking hydraulic motion is utilized to drive the vehicle and suitable direction and throttling controls are provided for controlling the delivery of a hydraulic driving fluid from a pressurized hydraulic fluid accumulator. A steering axis is steerable through a handle to steer the front wheels through a linkage assembly.

  1. Synthesis of high capacity cathodes for lithium-ion batteries by morphology-tailored hydroxide co-precipitation

    NASA Astrophysics Data System (ADS)

    Wang, Dapeng; Belharouak, Ilias; Ortega, Luis H.; Zhang, Xiaofeng; Xu, Rui; Zhou, Dehua; Zhou, Guangwen; Amine, Khalil

    2015-01-01

    Nickel manganese hydroxide co-precipitation inside a continuous stirred tank reactor was studied with sodium hydroxide and ammonium hydroxide as the precipitation agents. The ammonium hydroxide concentration had an effect on the primary and secondary particle evolution. The two-step precipitation mechanism proposed earlier was experimentally confirmed. In cell tests, Li- and Mn-rich composite cathode materials based on the hydroxide precursors demonstrated good electrochemical performance in terms of cycle life over a wide range of lithium content.

  2. Mercury (II) reduction and co-precipitation of metallic mercury on hydrous ferric oxide in contaminated groundwater.

    PubMed

    Richard, Jan-Helge; Bischoff, Cornelia; Ahrens, Christian G M; Biester, Harald

    2016-01-01

    Mercury (Hg) speciation and sorption analyses in contaminated aquifers are useful for understanding transformation, retention, and mobility of Hg in groundwater. In most aquifers hydrous ferric oxides (HFOs) are among the most important sorbents for trace metals; however, their role in sorption or mobilization of Hg in aquifers has been rarely analyzed. In this study, we investigated Hg chemistry and Hg sorption to HFO under changing redox conditions in a highly HgCl2-contaminated aquifer (up to 870μgL(-1) Hg). Results from aqueous and solid phase Hg measurements were compared to modeled (PHREEQC) data. Speciation analyses of dissolved mercury indicated that Hg(II) forms were reduced to Hg(0) under anoxic conditions, and adsorbed to or co-precipitated with HFO. Solid phase Hg thermo-desorption measurements revealed that between 55 and 93% of Hg bound to HFO was elemental Hg (Hg(0)). Hg concentrations in precipitates reached more than 4 weight %, up to 7000 times higher than predicted by geochemical models that do not consider unspecific sorption to and co-precipitation of elemental Hg with HFO. The observed process of Hg(II) reduction and Hg(0) formation, and its retention and co-precipitation by HFO is thought to be crucial in HgCl2-contaminated aquifers with variable redox-conditions regarding the related decrease in Hg solubility (factor of ~10(6)), and retention of Hg in the aquifer.

  3. Sample pretreatment in the determination of specific alpha emitters in drinking water using [Ba+Fe]-coprecipitation method.

    PubMed

    Suarez-Navarro, J A; Pujol, Ll; Suarez-Navarro, M J

    2015-02-01

    The [Ba+Fe]-coprecipitation method is applied to measure gross alpha activity for radiological examination of drinking water in the laboratory. This method collects all the alpha-emitting radionuclides of interest (natural alpha emitters and transuranium elements) in a precipitate on a filter. This paper describes an investigation of sample pretreatment of the precipitate collected by the [Ba+Fe]-coprecipitation method for gross alpha activity determination. The aim of this preliminary work is to be a starting point to develop simple and rapid radiochemical procedures for specific alpha emitters (polonium, radium, thorium, uranium, plutonium and americium), in contrast to the sophisticated, expensive and time-consuming alpha spectrometry method. The sample pretreatment aspects considered include quantitative [Ba+Fe]-coprecipitation, two methods for precipitate treatment (leaching and complete destruction of the filter), and the determination of the alpha-emitting proportions present in the barium sulfate precipitate and acid solution obtained after precipitate treatment. Furthermore, a radiochemical procedure for (226)Ra determination was performed and finally, the sample pretreatment proposed in this work was summarized.

  4. Study of the Influence Between Barium Ions and Calcium Ions on Morphology and Size of Coprecipitation in Microemulsion

    NASA Astrophysics Data System (ADS)

    Wang, Nong; Meng, Qing Luo

    2015-03-01

    In this paper, we systematically drew a series of inverse-microemulsion quasi-ternary system phase diagrams of OP-10+C8H17OH+C6H12+brine (CaCl2/BaCl2) by adjusting the ratio of CaCl2 and BaCl2. On this basis, microemulsions have been prepared with seven different molar ratios of Ca2+/Ba2+, and calcium carbonate and barium carbonate coprecipitation products were obtained by reaction with an equimolar amount of sodium carbonate. The influence of barium ion to morphology and composition of nanometer calcium carbonate were studied. These samples were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The SEM photographs indicated that when the content of Ca2+ was higher, some incomplete large cube of coprecipitation particles were formed in solution, but with the content of Ba2+ increased gradually, they formed a large number of small spherical particles, with the further increase of Ba2+ concentration, the particles mainly had structures of irregular polyhedron eventually. The measurement results of FTIR and XRD indicated that CaCO3 coprecipitation products gradually changed from calcite to the vaterite, eventually turned into being aragonite with the further increase of Ba2+ concentration.

  5. Sample pretreatment in the determination of specific alpha emitters in drinking water using [Ba+Fe]-coprecipitation method.

    PubMed

    Suarez-Navarro, J A; Pujol, Ll; Suarez-Navarro, M J

    2015-02-01

    The [Ba+Fe]-coprecipitation method is applied to measure gross alpha activity for radiological examination of drinking water in the laboratory. This method collects all the alpha-emitting radionuclides of interest (natural alpha emitters and transuranium elements) in a precipitate on a filter. This paper describes an investigation of sample pretreatment of the precipitate collected by the [Ba+Fe]-coprecipitation method for gross alpha activity determination. The aim of this preliminary work is to be a starting point to develop simple and rapid radiochemical procedures for specific alpha emitters (polonium, radium, thorium, uranium, plutonium and americium), in contrast to the sophisticated, expensive and time-consuming alpha spectrometry method. The sample pretreatment aspects considered include quantitative [Ba+Fe]-coprecipitation, two methods for precipitate treatment (leaching and complete destruction of the filter), and the determination of the alpha-emitting proportions present in the barium sulfate precipitate and acid solution obtained after precipitate treatment. Furthermore, a radiochemical procedure for (226)Ra determination was performed and finally, the sample pretreatment proposed in this work was summarized. PMID:25474768

  6. Nature and reactivity of layered double hydroxides formed by coprecipitating Mg, Al and As(V): Effect of arsenic concentration, pH, and aging.

    PubMed

    Sommella, Alessia; Caporale, Antonio G; Denecke, Melissa A; Mangold, Stefan; Pigna, Massimo; Santoro, Anna; Terzano, Roberto; Violante, Antonio

    2015-12-30

    Arsenic (As) co-precipitation is one of the major processes controlling As solubility in soils and waters. When As is co-precipitated with Al and Mg, the possible formation of layered double hydroxides (LDHs) and other nanocomposites can stabilize As in their structures thus making this toxic element less available. We investigated the nature and reactivity of Mg-Al-arsenate [As(V)] co-precipitated LDHs formed in solution affected by As concentration, pH, and aging. At the beginning of the co-precipitation process, poorly crystalline LDH and non-crystalline Al(Mg)-oxides form. Prolonged aging of the samples promotes crystallization of LDHs, evidenced by an increase in As K XANES intensities and XRD peak intensities. During aging Al- and/or Mg-oxides are likely transformed by dissolution/re-precipitation processes into more crystalline but still defective LDHs. Surface area, chemical composition, reactivity of the precipitates, and anion exchange properties of As(V) in the co-precipitates are influenced by pH, aging, and As concentration. This study demonstrates that (i) As(V) retards or inhibits the formation and transformation of LDHs and (ii) more As(V) is removed from solution if co-precipitated with Mg and Al than by sorption onto well crystallized LDHs. PMID:26241870

  7. Coprecipitation of Fe(II III) hydroxycarbonate green rust stabilised by phosphate adsorption

    NASA Astrophysics Data System (ADS)

    Bocher, Florent; Géhin, Antoine; Ruby, Christian; Ghanbaja, Jaafar; Abdelmoula, Mustapha; Génin, Jean-Marie R.

    2004-01-01

    [Fe II4Fe III2(OH) 12] 2+•[CO 3, nH 2O] 2- green rust one, GR1(CO 32-), was synthesised by coprecipitation in the presence of phosphate by dissolving a Na 2HPO 4 salt. In its absence, the resulting product is a mixture of Fe(II-III) hydroxysalt, magnetite Fe 3O 4 and ferrous hydroxide Fe(OH) 2. In the presence of phosphate as low as {[PO 4] min0/[Fe]}˜1%, the resulting product is GR1(CO 32-) alone. No P was detected by TEM-EDX when the basal (0001) crystal faces were analysed, showing that no P was inserted in the GR. In contrast, very low quantities of P were detected when the analyses were performed on the lateral faces of the GR crystals. Analysis of P in solution by ICP-AES evaluates the quantity of phosphate adsorbed species. A model representing the precipitate and its surface showed that the quantity of adsorbed phosphate has the same order of magnitude than the number of Fe atoms present on the lateral faces. The preference of phosphate species for lateral faces is due to the fact that the {10 1¯0} faces contain mono- and di-coordinated OH -surface groups. PO 43- adsorbed on the lateral faces may act as a barrier that slows down the release in solution of the CO 32- species preventing GR1(CO 32-) to transform into the mixture of Fe 3O 4 and Fe(OH) 2.

  8. BaFe12O19 powder with high magnetization prepared by acetone-aided coprecipitation

    NASA Astrophysics Data System (ADS)

    Yu, Hsuan-Fu

    2013-09-01

    BaFe12O19 particles with high magnetization were produced using an acetone-aided coprecipitation process. An aqueous solution of iron and barium nitrates, in an Fe3+/Ba2+ molar ratio of 12, was added in a stirred precipitation liquid medium composed of H2O, CH3(CO)CH3 and NH4OH. After reacting metallic ions with ammonia, the precipitates were formed, centrifugally filtered, freeze dried and calcined. Effects of amount of the acetone in the precipitation liquid medium on the formation of crystalline BaFe12O19 were investigated. The presence of acetone in the precipitation liquid medium can greatly promote formation of the crystalline BaFe12O19 at temperature as low as 650 °C and can enhance magnetization of the derived particles. On the other hand, raising the calcination temperature can effectively accelerate development of crystallite morphology and magnetic characters of the barium hexaferrites. While the barium hexaferrite powder obtained without acetone additions and calcined at 1000 °C had magnetization (measured at 50 kOe; M(50 kOe)) of 63.5 emu/g, remanence magnetization (Mr) of 31.3 emu/g and coercivity (Hc) of 4.7 kOe, the single magnetic domain size BaFe12O19 powder with M(50 kOe) of 70.6 emu/g, Mr of 34.4 emu/g and Hc of 3.7 kOe was produced at 1000 °C, using a precipitation liquid medium of 64 vol% acetone.

  9. 14 CFR Section 04 - Air Carrier Groupings

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Air Carrier Groupings Section 04 Section 04... REGULATIONS UNIFORM SYSTEM OF ACCOUNTS AND REPORTS FOR LARGE CERTIFICATED AIR CARRIERS Section 04 Air Carrier Groupings (a) All large certificated air carriers are placed into three basic air carrier groupings...

  10. 14 CFR Section 04 - Air Carrier Groupings

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Air Carrier Groupings Section 04 Section 04... REGULATIONS UNIFORM SYSTEM OF ACCOUNTS AND REPORTS FOR LARGE CERTIFICATED AIR CARRIERS Section 04 Air Carrier Groupings (a) All large certificated air carriers are placed into three basic air carrier groupings...

  11. 14 CFR Section 04 - Air Carrier Groupings

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Air Carrier Groupings Section 04 Section 04... REGULATIONS UNIFORM SYSTEM OF ACCOUNTS AND REPORTS FOR LARGE CERTIFICATED AIR CARRIERS Section 04 Air Carrier Groupings (a) All large certificated air carriers are placed into three basic air carrier groupings...

  12. 14 CFR Section 04 - Air Carrier Groupings

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Air Carrier Groupings Section 04 Section 04... REGULATIONS UNIFORM SYSTEM OF ACCOUNTS AND REPORTS FOR LARGE CERTIFICATED AIR CARRIERS Section 04 Air Carrier Groupings (a) All large certificated air carriers are placed into three basic air carrier groupings...

  13. CONCENTRATION AND DECONTAMINATION OF SOLUTIONS CONTAINING PLUTONIUM VALUES BY BISMUTH PHOSPHATE CARRIER PRECIPITATION METHODS

    DOEpatents

    Seaborg, G.T.; Thompson, S.G.

    1960-08-23

    A process is given for isolating plutonium present in the tetravalent state in an aqueous solution together with fission products. First, the plutonium and fission products are coprecipitated on a bismuth phosphate carrier. The precipitate obtained is dissolved, and the plutonium in the solution is oxidized to the hexavalent state (with ceric nitrate, potassium dichromate, Pb/ sub 3/O/sub 4/, sodium bismuthate and/or potassium dichromate). Thereafter a carrier for fission products is added (bismuth phosphate, lanthanum fluoride, ceric phosphate, bismuth oxalate, thorium iodate, or thorium oxalate), and the fission-product precipitation can be repeated with one other of these carriers. After removal of the fission-product-containing precipitate or precipitates. the plutonium in the supernatant is reduced to the tetravalent state (with sulfur dioxide, hydrogen peroxide. or sodium nitrate), and a carrier for tetravalent plutonium is added (lanthanum fluoride, lanthanum hydroxide, lanthanum phosphate, ceric phosphate, thorium iodate, thorium oxalate, bismuth oxalate, or niobium pentoxide). The plutonium-containing precipitate is then dissolved in a relatively small volume of liquid so as to obtain a concentrated solution. Prior to dissolution, the bismuth phosphate precipitates first formed can be metathesized with a mixture of sodium hydroxide and potassium carbonate and plutonium-containing lanthanum fluorides with alkali-metal hydroxide. In the solutions formed from a plutonium-containing lanthanum fluoride carrier the plutonium can be selectively precipitated with a peroxide after the pH was adjusted preferably to a value of between 1 and 2. Various combinations of second, third, and fourth carriers are discussed.

  14. Nanostructured lipid carriers: a potential drug carrier for cancer chemotherapy.

    PubMed

    Selvamuthukumar, Subramanian; Velmurugan, Ramaiyan

    2012-01-01

    Nanotechnology having developed exponentially, the aim has been on therapeutic undertaking, particularly for cancerous disease chemotherapy. Nanostructured lipid carriers have attracted expanding scientific and commercial vigilance in the last couple of years as alternate carriers for the pharmaceutical consignment, particularly anticancer pharmaceuticals. Shortcomings often came across with anticancer mixtures, such as poor solubility, normal tissue toxicity, poor specificity and steadiness, as well as the high incidence rate of pharmaceutical resistance and the rapid degradation, need of large-scale output procedures, a fast release of the pharmaceutical from its carrier scheme, steadiness troubles, the residues of the organic solvents utilized in the output method and the toxicity from the polymer with esteem to the carrier scheme are anticipated to be overcome through use of the Nanostructured Lipid Carrier. In this review the benefits, types, drug release modulations, steadiness and output techniques of NLCs are discussed. In supplement, the function of NLC in cancer chemotherapy is presented and hotspots in research are emphasized. It is foreseen that, in the beside future, nanostructured lipid carriers will be further advanced to consign cytotoxic anticancer compounds in a more efficient, exact and protected manner. PMID:23167765

  15. Co-precipitation of copper and niobium carbide in a low carbon steel

    NASA Astrophysics Data System (ADS)

    Gagliano, Michael Scott

    Co-precipitation of niobium carbide and body-centered cubic (BCC) copper in ferrite was investigated as a high strength, low carbon, chromium-free alternative to conventional high performance structural steels that rely on a tempered martensitic microstructure. Theoretical nucleation and growth rate models for BCC copper and niobium carbide were constructed using calculated thermodynamic driving forces in conjunction with classical theories for the homogeneous nucleation and subsequent growth of coherent, spherical precipitates. The maximum calculated nucleation and growth rates for niobium carbide were found to be 1.0 x 106 nuclei/cm3s at 666°C and 1.0 nm/s at 836°C, respectively, for an austenitizing temperature of 1170°C. For BCC copper in ferrite, the maximum calculated nucleation and growth rates were determined to be 8.0 x 1015 nuclei/cm 3s at 612°C and 0.038 nm/s at 682°C, respectively, for all austenitizing temperatures. Three-dimensional atom probe (3DAP) microscopy revealed the presence of nano-scale BCC copper clusters in approximately the same number density predicted by the theoretical nucleation model. Using an experimentally determined "effective" activation energy for copper in iron, the normalized theoretical nucleation rate curve compared very well with the normalized hardness response after 5 minutes of aging and effectively described the experimental short-time aging behavior of a low carbon, niobium bearing steel. The size and morphological evolution as well as the growth and coarsening behavior of copper precipitates were investigated through conventional TEM during isothermal direct aging at 550°C for a niobium and niobium-free steel. Although niobium carbide precipitation was not characterized, niobium additions provided increased hardness upon direct aging and showed a much higher resistance to overaging, than a niobium-free steel, for long isothermal aging times. In both steels for aging times up to five hours, both 9R type and BCC

  16. 49 CFR 369.3 - Classification of carriers-motor carriers of passengers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 5 2013-10-01 2013-10-01 false Classification of carriers-motor carriers of...) FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION FEDERAL MOTOR CARRIER SAFETY REGULATIONS REPORTS OF MOTOR CARRIERS § 369.3 Classification of carriers—motor carriers of passengers....

  17. 49 CFR 369.3 - Classification of carriers-motor carriers of passengers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Classification of carriers-motor carriers of...) FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION FEDERAL MOTOR CARRIER SAFETY REGULATIONS REPORTS OF MOTOR CARRIERS § 369.3 Classification of carriers—motor carriers of passengers....

  18. Stable wafer-carrier system

    DOEpatents

    Rozenzon, Yan; Trujillo, Robert T; Beese, Steven C

    2013-10-22

    One embodiment of the present invention provides a wafer-carrier system used in a deposition chamber for carrying wafers. The wafer-carrier system includes a base susceptor and a top susceptor nested inside the base susceptor with its wafer-mounting side facing the base susceptor's wafer-mounting side, thereby forming a substantially enclosed narrow channel. The base susceptor provides an upward support to the top susceptor.

  19. Coprecipitation of arsenate with metal oxides. 3. Nature, mineralogy, and reactivity of iron(III)-aluminum precipitates.

    PubMed

    Violante, Antonio; Pigna, Massimo; Del Gaudio, Stefania; Cozzolino, Vincenza; Banerjee, Dipanjan

    2009-03-01

    Coprecipitation involving arsenic with aluminum or iron has been studied because this technique is considered particularly efficient for removal of this toxic element from polluted waters. Coprecipitation of arsenic with mixed iron-aluminum solutions has received scant attention. In this work we studied (i)the mineralogy, surface properties, and chemical composition of mixed iron-aluminum oxides formed at initial Fe/Al molar ratio of 1.0 in the absence or presence of arsenate [As/ Fe+Al molar ratio (R) of 0, 0.01, or 0.1] and at pH 4.0, 7.0, and 10.0 and aged for 30 and 210 days at 50 degrees C and (ii) the removal of arsenate from the coprecipitates after addition of phosphate. The amounts of short-range ordered precipitates (ferrihydrite, aluminous ferrihydrite and/or poorly crystalline boehmite) were greater than those found in iron and aluminum systems (studied in previous works), due to the capacity of both aluminum and arsenate to retard or inhibitthe transformation of the initially formed precipitates into well-crystallized oxides (gibbsite, bayerite, and hematite). As a consequence, the surface areas of the iron-aluminum oxides formed in the absence or presence of arsenate were usually much larger than those of aluminum or iron oxides formed under the same conditions. Arsenate was found to be associated mainly into short-range ordered materials. Chemical composition of all samples was affected by pH, initial R, and aging. Phosphate sorption was facilitated by the presence of short-range ordered materials, mainly those richer in aluminum, but was inhibited by arsenate present in the samples. The quantities of arsenate replaced by phosphate, expressed as percentages of its total amount present in the samples, were particularly low, ranging from 10% to 26%. A comparison of the desorption of arsenate by phosphate from aluminum-arsenate and iron-arsenate (studied in previous works) and iron-aluminum-arsenate coprecipitates evidenced that phosphate has a greater

  20. Synthesis of the high temperature superconductor YBa 2Cu 3O 7-δ by the hydroxide co-precipitation method

    NASA Astrophysics Data System (ADS)

    Schildermans, I.; Van Bael, M.; Knaepen, E.; Yperman, J.; Mullens, J.; Van Poucke, L. C.

    1997-02-01

    A new synthetic route is developed to prepare a hydroxide precursor for the superconductor YBa 2Cu 3O 7-δ. In an inert atmosphere and at low temperature the yttrium, barium and copper hydroxides are co-precipitated by adding the metal perchlorates and sodium hydroxide together. The analysis of the precursor proved the absence of ClO 4- and Na + ions. The thermal treatment (12 h calcinating at 950°C, 36 h sintering at 950°C and 6 h annealing at 400°C) gives a superconductor YBa 2Cu 3O 7-δ with a transition temperature of 90.2 K.

  1. Effects of morphology on the structural and photoluminescence properties of co-precipitation derived GdVO4:Dy3+

    NASA Astrophysics Data System (ADS)

    Kumari, Puja; Manam, J.

    2016-10-01

    Herein, Dy3+ doped GdVO4 samples with various morphologies were prepared by the co-precipitation method at low temperature, and the effects of different morphologies on the structural and optical behaviors have been reported. The obtained samples were stabilized to the stable tetragonal structure. The IR and FESEM study were carried out to see the vibrational bonds position and surface morphology. At present PL, PLE, diffuse reflectance and decay curves have been discussed in detail. The morphology dependent photoluminescence studies were resulted to a suitable sample for the lighting and display applications.

  2. Germanium isotope fractionation during Ge adsorption on goethite and its coprecipitation with Fe oxy(hydr)oxides

    NASA Astrophysics Data System (ADS)

    Pokrovsky, Oleg S.; Galy, Albert; Schott, Jacques; Pokrovski, Gleb S.; Mantoura, Samia

    2014-04-01

    Isotopic fractionation of Ge was studied during Ge adsorption on goethite and its coprecipitation with amorphous Fe oxy(hydr)oxides. Regardless of the pH, surface concentration of adsorbed Ge or exposure time, the solution-solid enrichment factor for adsorption (Δ74/70Gesolution-solid) was 1.7 ± 0.1‰. The value of the Δ74Gesolution-solid in Fe-Ge coprecipitates having molar ratio 0.1 < (Ge/Fe)solid < 0.5 remained constant at 2.0 ± 0.4‰. For (Ge/Fe)solid ratio < 0.1, the Δ74Gesolution-solid increased with the decrease of Ge concentration in the solid phase, with the value as high as 4.4 ± 0.2‰ at (Ge/Fe)solid < 0.001, corresponding to the majority of natural settings. These results can be interpreted based on available structural data for adsorbed and coprecipitated Ge. It follows that Ge(OH)4° adsorption occurring as bidentate binuclear complexes at the goethite surface is characterised by an enrichment factor of ∼1.7‰, likely related to the distortion of the GeO4 tetrahedron and the formation of Ge-O-Fe bonds at the goethite surface as compared to aqueous solution. In contrast, coprecipitation yields more distorted edge-sharing GeO4 tetrahedra and, in the case of the most diluted samples, part of the Ge is found in coordination 6, replacing Fe(III) in octahedral positions. This produces a greater enrichment of the solid phase in lighter isotopes, mostly due to the increase in Ge-O bond distances and coordination number compared to aqueous solution, which is in line with the basic principles of isotope fractionation. Discharge of hydrothermal fluids, leading to massive Fe(OH)3 precipitation in the vicinity of the springs should, therefore, represent an isotopically-heavy source of dissolved Ge to the ocean. Similarly, groundwater discharge and Fe(OH)3 precipitation at the Earth’s surface, Fe oxy(hydr)oxide formation in soils and riverine organo-ferric colloids coagulation, leading to iron hydroxide precipitation in estuaries, should produce an

  3. Preparation of nano-sized magnetic particles from spent pickling liquors by ultrasonic-assisted chemical co-precipitation.

    PubMed

    Tang, Bing; Yuan, Liangjun; Shi, Taihong; Yu, Linfeng; Zhu, Youchun

    2009-04-30

    The aim of this study is to develop a new method for the preparation of high-value, environmentally friendly products from spent pickling liquors. An ultrasound treatment was introduced into a chemical co-precipitation process to control the size of the particles produced. The particles were characterized by X-ray powder diffraction and transmission electron microscopy. The magnetic parameter was measured with a magnetic property measurement system. The product consisted of ferrous ferrite (Fe(3)O(4)) nano-sized cubic particles with a high level of crystallinity that exhibited super-paramagnetism. PMID:18762377

  4. Quality-by-design: an integrated process analytical technology approach to determine the nucleation and growth mechanisms during a dynamic pharmaceutical coprecipitation process.

    PubMed

    Wu, Huiquan; Khan, Mansoor A

    2011-05-01

    The objective of this study was to demonstrate the feasibility of using an integrated process analytical technology (PAT) approach to determine nucleation and growth mechanisms of a dynamic naproxen (drug)-Eudragit L100 (polymer) coprecipitation process. The influence of several thermodynamically important formulation and process variables (drug/polymer ratio, alcohol, and water usages) on coprecipitation process characteristics was investigated via real-time in situ focused beam reflectance measurement (FBRM) monitoring and near real-time particle vision microscopy measurement. The final products were characterized by near-infrared (NIR) spectroscopy and NIR chemical imaging microscopy. The coprecipitation nucleation induction time (t(ind) ) was measured by both FBRM trend statistics and process trajectory method, respectively. Furthermore, nucleation kinetics was evaluated based on t(ind) measurement and corresponding supersaturation ratio (S) estimated. It was found that plots of ln(t(ind) ) versus (ln(2) S)(-1) consist of two linear segments and are consistent with classical primary nucleation mechanisms. Apparently, the coprecipitation process is governed by heterogeneous primary nucleation mechanism at low S (14 ≤ S ≤ 503) and by homogeneous primary nucleation mechanism at high S (1216 ≤ S ≤ 3649). Off-line characterizations collectively supported this statement. Therefore, it demonstrated that integration real-time PAT process monitoring with first-principles modeling and off-line product characterization could enhance understanding to coprecipitation process dynamics and nucleation/growth mechanisms, which is impossible via off-line techniques alone.

  5. Synthesis of layered double hydroxides containing Mg2+, Zn2+, Ca2+ and Al3+ layer cations by co-precipitation methods-A review

    NASA Astrophysics Data System (ADS)

    Theiss, Frederick L.; Ayoko, Godwin A.; Frost, Ray L.

    2016-10-01

    Co-precipitation is a common method for the preparation of layered double hydroxides (LDHs) and related materials. This review article is aimed at providing newcomers to the field with some examples of the types of co-precipitation reactions that have been reported previously and to briefly investigate some of the properties of the products of these reactions. Due to the sheer volume of literature on the subject, the authors have had to limit this article to the synthesis of Mg/Al, Zn/Al and Ca/Al LDHs by co-precipitation and directly related methods. LDHs have been synthesised from various reagents including metal salts, oxides and hydroxides. Co-precipitation is also useful for the direct synthesis of LDHs with a wide range of interlayer anions and various bases have been successfully employed to prepare LDHs. Examples of other synthesis techniques including the urea method, hydrothermal synthesis and various mechanochemical methods that are undoubtedly related to co-precipitation have also been included in this review. The effect of post synthesis hydrothermal has also been summarised.

  6. Phase stability and rapid consolidation of hydroxyapatite-zirconia nano-coprecipitates made using continuous hydrothermal flow synthesis.

    PubMed

    Chaudhry, Aqif A; Yan, Haixue; Viola, Giuseppe; Reece, Mike J; Knowles, Jonathan C; Gong, Kenan; Rehman, Ihtesham; Darr, Jawwad A

    2012-07-01

    A rapid and continuous hydrothermal route for the synthesis of nano-sized hydroxyapatite rods co-precipitated with calcium-doped zirconia nanoparticles using a superheated water flow at 450°C and 24.1 MPa as a crystallizing medium is described. Hydroxyapatite and calcium-doped zirconia phases in the powder mixtures could be clearly identified based on particle size and morphology under transmission electron microscopy. Retention of a nanostructure after sintering is crucial to load-bearing applications of hydroxyapatite-based ceramics. Therefore, rapid consolidation of the co-precipitates was investigated using a spark plasma sintering furnace under a range of processing conditions. Samples nominally containing 5 and 10 wt% calcium-doped zirconia and hydroxyapatite made with Ca:P solution molar ratio 2.5 showed excellent thermal stability (investigated using in situ variable temperature X-ray diffraction) and were sintered via spark plasma sintering to >96% sintered densities at 1000°C resulting in hydroxyapatite and calcium-doped zirconia as the only two phases. Mechanical tests of spark plasma sintering sintered samples (containing 10 wt% calcium-doped zirconia) revealed a three-pt flexural strength of 107.7 MPa and Weibull modulus of 9.9. The complementary nature of the spark plasma sintering technique and continuous hydrothermal flow synthesis (which results in retention of a nanostructure even after sintering at elevated temperatures) was hence showcased.

  7. Particle size and magnetic properties dependence on growth temperature for rapid mixed co-precipitated magnetite nanoparticles

    NASA Astrophysics Data System (ADS)

    Fang, Mei; Ström, Valter; Olsson, Richard T.; Belova, Lyubov; Rao, K. V.

    2012-04-01

    Magnetite nanoparticles have been prepared by co-precipitation using a custom-designed jet mixer to achieve rapid mixing (RM) of reactants in a timescale of milliseconds. The quick and stable nucleation obtained allows control of the particle size and size distribution via a more defined growth process. Nanoparticles of different sizes were prepared by controlling the processing temperature in the first few seconds post-mixing. The average size of the nanoparticles investigated using a Tecnai transmission electron microscope is found to increase with the temperature from 3.8 nm at 1 ± 1 °C to 10.9 nm for particles grown at 95 ± 1 °C. The temperature dependence of the size distribution follows the same trend and is explained in terms of Ostwald ripening of the magnetite nanoparticles during the co-precipitation of Fe2+ and Fe3+. The magnetic properties were studied by monitoring the blocking temperature via both DC and AC techniques. Strikingly, the obtained RM particles maintain the high magnetization (as high as ˜88 A m2 kg-1 at 500 kA m-1) while the coercivity is as low as ˜12 A m-1 with the expected temperature dependence. Besides, by adding a drop of tetramethylammonium hydroxide, aqueous ferrofluids with long term stability are obtained, suggesting their suitability for applications in ferrofluid technology and biomedicine.

  8. Effect of pH value on electromagnetic loss properties of Co-Zn ferrite prepared via coprecipitation method

    NASA Astrophysics Data System (ADS)

    Huang, Xiaogu; Zhang, Jing; Wang, Wei; Sang, Tianyi; Song, Bo; Zhu, Hongli; Rao, Weifeng; Wong, Chingping

    2016-05-01

    In this paper, the cobalt zinc ferrite was prepared by coprecipitation method at different pH conditions. The influence of pH values on the coprecipitation reaction was theoretically analyzed at first. The calculated results showed that the pH values should be controlled in the range of 9-11 to form the stable precipitation. The XRD investigation was used to further confirm the formation of the composite on specific pH values. In addition, the morphological study revealed that the average particle size of the composite decreased from 40 nm to 30 nm when the pH value increased from 9-11. The variation of microstructure plays a critical role in controlling the electromagnetic properties. From the electromagnetic analysis, the dielectric loss factor was 0.02-0.07 and magnetic loss factor was 0.2-0.5 for the composite synthesized at pH of 9, which presents dramatically improved dielectric loss and magnetic loss properties than the samples prepared at pH of 10 and 11. The as-prepared cobalt zinc ferrite are highly promising to be used as microwave absorption materials.

  9. Adsorption mechanisms of thallium(I) and thallium(III) by titanate nanotubes: ion-exchange and co-precipitation.

    PubMed

    Liu, Wen; Zhang, Pan; Borthwick, Alistair G L; Chen, Hao; Ni, Jinren

    2014-06-01

    Hydrothermally-synthesized titanate nanotubes (TNTs) are found to be excellent at adsorption of highly toxic thallium ions. Uptake of both thallium ions is very fast in the first 10 min. The adsorption isotherm of Tl(I) follows the Langmuir model with maximum adsorption capacity of 709.2 mg g(-1). Ion-exchange between Tl(+) and Na(+) in the interlayers of TNTs is the primary mechanism for Tl(I) adsorption. Excess Tl(+) undergoes further exchange with H(+). The adsorption mechanism is different for Tl(III), and involves either ion-exchange with Na(+) at low Tl(III) concentration or co-precipitation in the form of Tl(OH)3 with TNTs at high Tl(III) concentration. XPS analysis indicates that the ion-exchange process does not change the basic skeleton [TiO6] of TNTs, whereas Tl(OH)3 precipitation increases the percentage composition of O within the surface hydroxyl groups. XRD analysis also confirms the formation of Tl(OH)3 on TNTs at high initial concentration of Tl(III). Coexisting Na(+) and Ca(2+) hardly inhibit adsorption, indicating good selectivity for thallium by TNTs. Furthermore, TNTs can be reused efficiently after HNO3 desorption and NaOH regeneration, making TNTs a promising material to remove thallium from wastewaters. This study also confirms that co-precipitation is another important adsorption mechanism for easily hydrolytic metals by TNTs.

  10. Particle size and magnetic properties dependence on growth temperature for rapid mixed co-precipitated magnetite nanoparticles.

    PubMed

    Fang, Mei; Ström, Valter; Olsson, Richard T; Belova, Lyubov; Rao, K V

    2012-04-13

    Magnetite nanoparticles have been prepared by co-precipitation using a custom-designed jet mixer to achieve rapid mixing (RM) of reactants in a timescale of milliseconds. The quick and stable nucleation obtained allows control of the particle size and size distribution via a more defined growth process. Nanoparticles of different sizes were prepared by controlling the processing temperature in the first few seconds post-mixing. The average size of the nanoparticles investigated using a Tecnai transmission electron microscope is found to increase with the temperature from 3.8 nm at 1 ± 1 °C to 10.9 nm for particles grown at 95 ± 1 °C. The temperature dependence of the size distribution follows the same trend and is explained in terms of Ostwald ripening of the magnetite nanoparticles during the co-precipitation of Fe(2+) and Fe(3+). The magnetic properties were studied by monitoring the blocking temperature via both DC and AC techniques. Strikingly, the obtained RM particles maintain the high magnetization (as high as ∼88 A m(2) kg(-1) at 500 kA m(-1)) while the coercivity is as low as ∼12 A m(-1) with the expected temperature dependence. Besides, by adding a drop of tetramethylammonium hydroxide, aqueous ferrofluids with long term stability are obtained, suggesting their suitability for applications in ferrofluid technology and biomedicine. PMID:22433909

  11. Evaluation of Three Chitin Metal Silicate Co-Precipitates as a Potential Multifunctional Single Excipient in Tablet Formulations

    PubMed Central

    Hamid, Rana Al-Shaikh; Al-Akayleh, Faisal; Shubair, Mohammad; Rashid, Iyad; Remawi, Mayyas Al; Badwan, Adnan

    2010-01-01

    The performance of the novel chitin metal silicate (CMS) co-precipitates as a single multifunctional excipient in tablet formulation using direct compression and wet granulation methods is evaluated. The neutral, acidic, and basic drugs Spironolactone (SPL), ibuprofen (IBU) and metronidazole (MET), respectively, were used as model drugs. Commercial Aldactone®, Fleximex® and Dumazole® tablets containing SPL, IBU and MET, respectively, and tablets made using Avicel® 200, were used in the study for comparison purposes. Tablets of acceptable crushing strength (>40 N) were obtained using CMS. The friability values for all tablets were well below the maximum 1% USP tolerance limit. CMS produced superdisintegrating tablets (disintegration time < 1 min) with the three model drugs. Regarding the dissolution rate, the sequence was as follow: CMS > Fleximex® > Avicel® 200, CMS > Avicel® 200 > Dumazole® and Aldactone® > Avicel® 200 > CMS for IBU, MET and SPL, respectively. Compressional properties of formulations were analyzed using density measurements and the compression Kawakita equation as assessment parameters. On the basis of DSC results, CMS co precipitates were found to be compatible with the tested drugs. Conclusively, the CMS co-precipitates have the potential to be used as filler, binder, and superdisintegrant, all-in-one, in the design of tablets by the direct compression as well as wet granulation methods. PMID:20559493

  12. Oxidation of aqueous EDTA and associated organics and coprecipitation of inorganics by ambient iron-mediated aeration.

    PubMed

    Englehardt, James D; Meeroff, Daniel E; Echegoyen, Luis; Deng, Yang; Raymo, Françisco M; Shibata, Tomoyuki

    2007-01-01

    Cationic metal and radionuclide contaminants can be extracted from soils to groundwater with sequestering agents such as EDTA. However, EDTA must then be removed fromthe groundwater, by advanced oxidation or specialized biological treatment. In this work, aqueous individual metal-EDTA solutions were aerated with steel wool for 25 h, at ambient pH, temperature, and pressure. Removal of approximately 99% of EDTA (0.09-1.78 mM); glyoxylic acid (0.153 mM); chelated Cd2+ (0.94 and 0.0952 mM), Pb2+ (0.0502 mM), and Hg2+ (0.0419 mM); and free chromate and vanadate was shown. EDTA was oxidized to glyoxylic acid and formaldehyde, and metals/metalloids were coprecipitated together with iron oxyhydroxide floc. Free arsenite and arsenate were each removed at 99.97%. Free Sr2+, and chelated Ni2+ were removed at 92% and 63%, respectively. Similar removals were obtained from mixtures, including 99.996+/-0.004% removal of total arsenic (95% confidence). Traces of iminodiacetic acid, nitrilotriacetic acid, and ethylenediaminetriacetic acid were detected after 25 h. Results are consistent with first-order, solution-phase oxidation of EDTA and glyoxylic acid by ferryl ion and H202, respectively, with inhibition due to sludge accumulation, and equilibrium metal coprecipitation. This ambient process, to our knowledge previously unknown, agrees with recently reported findings and shows promise for remediation of metals, metalloids, and radionuclides in wastewater, soil, and sediment.

  13. New Synthesis Route and Characterization of Siderite (FeCO{sub 3} ) and Coprecipitation of {sup 99}Tc

    SciTech Connect

    Llorens, Isabelle; Fattahi, Massoud; Grambow, Bernd

    2007-07-01

    Technetium-99 is a long-lived product of nuclear fission. In the ground-waters of European disposal sites Tc is expected to be in the tetravalent state since the geochemical conditions are reducing due to the presence of redox couples such as Fe(II)/Fe(III), and the presence of reducing minerals such as pyrite and siderite (FeCO{sub 3}). Siderite is expected to be formed as well as container corrosion product. Experiments of coprecipitation of Fe{sup 2+} and Tc(IV) were conducted in the laboratory under an inert atmosphere at room temperature. High resolution transmission electron microscopy shows that the co-precipitate is around 3 nm sized particles. Analytical electron microscopy indicates that the precipitate contains 30 atom % of Tc and 70 atom % Fe. The Tc was homogeneously distributed. Selected Area Electron Diffraction does not reveal the formation of siderite, which suggests that the presence of technetium in high concentration inhibit the formation of this phase. (authors)

  14. Surface chemistry of ferrihydrite: Part 1. EXAFS studies of the geometry of coprecipitated and adsorbed arsenate

    NASA Astrophysics Data System (ADS)

    Waychunas, G. A.; Rea, B. A.; Fuller, C. C.; Davis, J. A.

    1993-05-01

    EXAFS spectra were collected on both the As and Fe K-edges from samples of two-line ferrihydrite with adsorbed (ADS) and coprecipitated (CPT) arsenate prepared over a range of conditions and arsenate surface coverages. Spectra also were collected for arsenate adsorbed on the surfaces of three FeOOH crystalline polymorphs, α (goethite), β (akaganeite), and γ (lepidocrocite), and as a free ion in aqueous: solution. Analyses of the As EXAFS show clear evidence for inner sphere bidentate (bridging) arsenate complexes on the ferrihydrite surface and on the surfaces of the crystalline FeOOH polymorphs. The bridging arsenate is attached to adjacent apices of edge-sharing Fe oxyhydroxyl octahedra. The arsenic-iron distance at the interface ( 3.28 ±0.01 Å) is close to that expected for this geometry on the FeOOH polymorph surfaces, but is slightly shorter on the ferrihydrite surfaces ( 3.25 ± 0.02 Å). Mono-dentate arsenate linkages ( 3.60 ± 0.03 Å) also occur on the ferrihydrite, but are not generally observed on the crystalline FeOOH polymorphs. The proportion of monodentate bonds appears largest for adsorption samples with the smallest As/Fe molar ratio. In all cases the arsenate tetrahedral complex is relatively undistorted with As-O bonds of 1.66 ± 0.01 Å. Precipitation of arsenate or scorodite-like phases was not observed for any samples, all of which were prepared at a pH value of 8. The Fe EXAFS results confirm that the Fe-Fe correlations in the ferrihydrite are progressively disrupted in the CPT samples as the As/Fe ratio is increased. Coherent crystallite size is probably no more than 10 Å in diameter and no Fe oxyhydroxyl octahedra corner-sharing linkages (as would be present in FeOOH polymorphs) are observed at the largest As/Fe ratios. Comparison of the number and type of Fe-Fe neighbors with the topological constraints imposed by the arsenate saturation limit in the CPT samples (about 0.7 As/Fe) indicates ferrihydrite units consisting mainly of Fe

  15. Surface chemistry of ferrihydrite: Part 1. EXAFS studies of the geometry of coprecipitated and adsorbed arsenate

    USGS Publications Warehouse

    Waychunas, G.A.; Rea, B.A.; Fuller, C.C.; Davis, J.A.

    1993-01-01

    EXAFS spectra were collected on both the As and Fe K-edges from samples of two-line ferrihydrite with adsorbed (ADS) and coprecipitated (CPT) arsenate prepared over a range of conditions and arsenate surface coverages. Spectra also were collected for arsenate adsorbed on the surfaces of three FeOOH crystalline polymorphs, ?? (goethite), ?? (akaganeite), and ?? (lepidocrocite), and as a free ion in aqueous: solution. Analyses of the As EXAFS show clear evidence for inner sphere bidentate (bridging) arsenate complexes on the ferrihydrite surface and on the surfaces of the crystalline FeOOH polymorphs. The bridging arsenate is attached to adjacent apices of edge-sharing Fe oxyhydroxyl octahedra. The arsenic-iron distance at the interface (3.28 ??0.01 A ??) is close to that expected for this geometry on the FeOOH polymorph surfaces, but is slightly shorter on the ferrihydrite surfaces (3.25 ?? 0.02 A ??). Mono-dentate arsenate linkages (3.60 ?? 0.03 A ??) also occur on the ferrihydrite, but are not generally observed on the crystalline FeOOH polymorphs. The proportion of monodentate bonds appears largest for adsorption samples with the smallest As Fe molar ratio. In all cases the arsenate tetrahedral complex is relatively undistorted with As-O bonds of 1.66 ?? 0.01 A ??. Precipitation of arsenate or scorodite-like phases was not observed for any samples, all of which were prepared at a pH value of 8. The Fe EXAFS results confirm that the Fe-Fe correlations in the ferrihydrite are progressively disrupted in the CPT samples as the As Fe ratio is increased. Coherent crystallite size is probably no more than 10 A?? in diameter and no Fe oxyhydroxyl octahedra corner-sharing linkages (as would be present in FeOOH polymorphs) are observed at the largest As Fe ratios. Comparison of the number and type of Fe-Fe neighbors with the topological constraints imposed by the arsenate saturation limit in the CPT samples (about 0.7 As Fe) indicates ferrihydrite units consisting mainly

  16. Spectroscopic characterization of co-precipitated arsenic- and iron-bearing sulfide phases at circum-neutral pH

    NASA Astrophysics Data System (ADS)

    Illera, V.; Rivera, N. A.; O'Day, P. A.

    2009-12-01

    Precipitation of arsenic- and iron-sulfide phases from porewaters is an important mechanism for removing arsenic and other contaminant metals from solution, thus reducing their bioaccessibility and potential toxicity. Although sulfide phases form readily at low pH, the identity, crystallinity, and local structure of arsenic and iron co-precipitated phases that form at circum-neutral pH are less well known. In this study, co-precipitated As+Fe sulfide phases and end-member As-sulfides and Fe-sulfides were synthesized in batch experiments and in a gas-tight reaction vessel at 25°C. Reduced conditions were maintained by keeping a constant flow of a 95%N2 /5%H2 mixture gas. Fresh saturated solutions of 0.3 M Fe(II) or Fe(III), 0.3 M S2- and 0.2 M As(III) ions were mixed and pH was maintained at pH 4, 6 and 8 by small additions of concentrated HCl or NaOH. At different time intervals, aliquots were extracted from suspensions aged from hours to 1 month and analyzed for total iron, arsenic and sulfur (by ICP-OES and ICP-MS). The Fe-S-As precipitates were characterized by X-ray diffraction (XRD) and synchrotron X-ray absorption spectroscopy (XAS). X-ray diffraction and Fe k-edge EXAFS showed the precipitation of amorphous to poorly crystalline iron sulfide when Fe(II) was co-precipitated with sulfide (no arsenic) at pH 4, 6, and 8. The precipitate that formed in ~1-4 h was nanoparticle-sized and disordered mackinawite (FeS), which showed a characteristic broad, low-intensity Bragg peaks in the XRD patterns. After aging for ~7 d, XRD patterns showed a change to more crystalline mackinawite. In contrast, co-precipitation of As(III) with Fe(II) and sulfide resulted in x-ray amorphous (both synchrotron and laboratory XRD) precipitates for all pH and aging times (~4 h to 1 m). Arsenic and iron XANES and EXAFS spectra of precipitates at pH 4 showed a mixture of amorphous orpiment-type (As2S3) and mackinawite-type (FeS) phases. At pH 6 and 8, XANES showed As sulfide and a

  17. 29 CFR 1201.1 - Carrier.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 4 2010-07-01 2010-07-01 false Carrier. 1201.1 Section 1201.1 Labor Regulations Relating to Labor (Continued) NATIONAL MEDIATION BOARD DEFINITIONS § 1201.1 Carrier. The term carrier includes any express company, sleeping car company, carrier by railroad, subject to the Interstate Commerce...

  18. 29 CFR 1201.1 - Carrier.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 4 2014-07-01 2014-07-01 false Carrier. 1201.1 Section 1201.1 Labor Regulations Relating to Labor (Continued) NATIONAL MEDIATION BOARD DEFINITIONS § 1201.1 Carrier. The term carrier includes any express company, sleeping car company, carrier by railroad, subject to the Interstate Commerce...

  19. 29 CFR 1201.1 - Carrier.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 4 2012-07-01 2012-07-01 false Carrier. 1201.1 Section 1201.1 Labor Regulations Relating to Labor (Continued) NATIONAL MEDIATION BOARD DEFINITIONS § 1201.1 Carrier. The term carrier includes any express company, sleeping car company, carrier by railroad, subject to the Interstate Commerce...

  20. 29 CFR 1201.1 - Carrier.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 4 2011-07-01 2011-07-01 false Carrier. 1201.1 Section 1201.1 Labor Regulations Relating to Labor (Continued) NATIONAL MEDIATION BOARD DEFINITIONS § 1201.1 Carrier. The term carrier includes any express company, sleeping car company, carrier by railroad, subject to the Interstate Commerce...

  1. 29 CFR 1202.13 - Air carriers.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 4 2013-07-01 2013-07-01 false Air carriers. 1202.13 Section 1202.13 Labor Regulations Relating to Labor (Continued) NATIONAL MEDIATION BOARD RULES OF PROCEDURE § 1202.13 Air carriers. By the... carrier by air engaged in interstate or foreign commerce, and every carrier by air transporting mail...

  2. 29 CFR 1202.13 - Air carriers.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 4 2011-07-01 2011-07-01 false Air carriers. 1202.13 Section 1202.13 Labor Regulations Relating to Labor (Continued) NATIONAL MEDIATION BOARD RULES OF PROCEDURE § 1202.13 Air carriers. By the... carrier by air engaged in interstate or foreign commerce, and every carrier by air transporting mail...

  3. 29 CFR 1202.13 - Air carriers.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 4 2012-07-01 2012-07-01 false Air carriers. 1202.13 Section 1202.13 Labor Regulations Relating to Labor (Continued) NATIONAL MEDIATION BOARD RULES OF PROCEDURE § 1202.13 Air carriers. By the... carrier by air engaged in interstate or foreign commerce, and every carrier by air transporting mail...

  4. 29 CFR 1202.13 - Air carriers.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 4 2014-07-01 2014-07-01 false Air carriers. 1202.13 Section 1202.13 Labor Regulations Relating to Labor (Continued) NATIONAL MEDIATION BOARD RULES OF PROCEDURE § 1202.13 Air carriers. By the... carrier by air engaged in interstate or foreign commerce, and every carrier by air transporting mail...

  5. 29 CFR 1202.13 - Air carriers.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 4 2010-07-01 2010-07-01 false Air carriers. 1202.13 Section 1202.13 Labor Regulations Relating to Labor (Continued) NATIONAL MEDIATION BOARD RULES OF PROCEDURE § 1202.13 Air carriers. By the... carrier by air engaged in interstate or foreign commerce, and every carrier by air transporting mail...

  6. Straddle carrier radiation portal monitoring

    NASA Astrophysics Data System (ADS)

    Andersen, Eric S.; Samuel, Todd J.; Mullen, O. Dennis

    2005-05-01

    U.S. Customs and Border Protection (CBP) is the primary enforcement agency protecting the nation"s ports of entry. CBP is enhancing its capability to interdict the illicit import of nuclear and radiological materials and devices that may be used by terrorists. Pacific Northwest National Laboratory (PNNL) is providing scientific and technical support to CBP in their goal to enable rapid deployment of nuclear and radiation detection systems at U. S. ports of entry to monitor 100% of the incoming international traffic and cargo while not adversely impacting the operations or throughput of the ports. The U.S. ports of entry include the following vectors: land border crossings, seaports, airports, rail crossings, and mail and express consignment courier facilities. U.S. Customs and Border Protection (CBP) determined that a screening solution was needed for Seaport cargo containers being transported by Straddle Carriers (straddle carriers). A stationary Radiation Portal Monitor (RPM) for Straddle Carriers (SCRPM) is needed so that cargo containers can be scanned while in transit under a Straddle Carrier. The Straddle Carrier Portal operational impacts were minimized by conducting a time-motion study at the Port, and adaptation of a Remotely Operated RPM (RO-RPM) booth concept that uses logical lighting schemes for traffic control, cameras, Optical Character Recognition, and wireless technology.

  7. Straddle Carrier Radiation Portal Monitoring

    SciTech Connect

    Andersen, Eric S.; Samuel, Todd J.; Mullen, O Dennis

    2005-08-01

    U.S. Customs and Border Protection (CBP) is the primary enforcement agency protecting the nation’s ports of entry. CBP is enhancing its capability to interdict the illicit import of nuclear and radiological materials and devices that may be used by terrorists. Pacific Northwest National Laboratory (PNNL) is providing scientific and technical support to CBP in their goal to enable rapid deployment of nuclear and radiation detection systems at U. S. ports of entry to monitor 100% of the incoming international traffic and cargo while not adversely impacting the operations or throughput of the ports. The U.S. ports of entry include the following vectors: land border crossings, seaports, airports, rail crossings, and mail and express consignment courier facilities. U.S. Customs and Border Protection (CBP) determined that a screening solution was needed for Seaport cargo containers being transported by Straddle Carriers (straddle carriers). A stationary Radiation Portal Monitor (RPM) for Straddle Carriers (SCRPM) is needed so that cargo containers can be scanned while in transit under a Straddle Carrier. The Straddle Carrier Portal operational impacts were minimized by conducting a time-motion study at the Port, and adaptation of a Remotely Operated RPM (RO-RPM) booth concept that uses logical lighting schemes for traffic control, cameras, Optical Character Recognition, and wireless technology.

  8. Residual Versus Suppressed-Carrier Coherent Communications

    NASA Astrophysics Data System (ADS)

    Simon, M. K.; Million, S.

    1996-07-01

    This article addresses the issue of when to suppress or not to suppress the transmitted carrier in designing a coherent communication system employing a carrier tracking loop for carrier synchronization. Assuming that a phase-locked loop (PLL) is used whenever there exists a residual carrier and a Costas loop is used whenever the carrier is suppressed, the regions of system parameters that delineate these two options are presented based on the desire to minimize the average probability of error of the system.

  9. Carrier sense data highway system

    DOEpatents

    Frankel, Robert

    1984-02-14

    A data transmission system includes a transmission medium which has a certain propagation delay time over its length. A number of data stations are successively coupled to the transmission medium for communicating with one another. Each of the data stations includes a transmitter for originating signals, each signal beginning with a carrier of a duration which is at least the propagation delay time of the transmission medium. Each data station also includes a receiver which receives other signals from other data stations and inhibits operation of the transmitter at the same data station when a carrier of another signal is received.

  10. Decontamination of alkaline solution from technetium and other fission products and from some actinides by reductive coprecipitation and sorption on metals

    SciTech Connect

    Peretrukhin, V.F.; Silin, V.I.; Tananaev, I.G.; Kareta, A.V.; Trushina, V.E.

    1997-09-01

    Effective decontamination of alkaline solutions and Hanford Site tank waste simulants from technetium has been accomplished by reductive coprecipitation with iron(III) hydroxide. Addition of 1 M (NH{sub 4}){sub 2}Fe(SO{sub 4}){sub 2} to 0.5 to 4.0 M NaOH to a final concentration of 0.1 to 0.15 M coprecipitates more than 99% of the technetium. from 0.5 to 1.0 M NaOH and 98 to 96% from 2.0 to 4.0 M NaOH. Similar results were obtained by reduction of Tc(VII) with 0.1 to 0.15 M hydrazine and subsequent addition of FeCl{sub 3} to a final concentration of 0.15 M. Inclusion of four complex-forming agents [0.01 M phosphate, 0.1 M EDTA (ethylenediaminetetraacetate), 0.03 M citrate, and 0.1 M glycolate (HOCH{sub 2}CO{sub 2}{sup -})] to the alkaline solution decreases technetium coprecipitation with iron hydroxide to 85% under otherwise similar conditions. Inclusion of 0.04 M Na{sub 2}CrO{sub 4} drastically decreases reductive coprecipitation of Tc(VII) in 0.5 to 4.0 M NaOH. Iron(II) salt, added to a 0.07 M excess over that of chromate, completely reduces chromate and provides greater than 99% coprecipitation of technetium with product iron(III) and chromium(III) hydroxides. Technetium(VII) reduction by hydrazine is slow in the presence of chromate in alkaline solution, and technetium coprecipitation is incomplete in these conditions. Decontamination of an alkaline Hanford Site tank waste simulant, containing 0.04M chromate and eleven salts and complex-forming agents, by adding 1 M iron(II) salt solution was studied. Coprecipitation of 15 to 28% of the technetium and more than 99% of the plutonium occurred in the Fe/Cr(III) hydroxide precipitate produced by adding 0.05 to 0.10 M iron(II). Chromate reduction was incomplete. About 75% of the technetium was coprecipitated, and the chromate was completely reduced, after adding 0.2 M iron(II) salt.

  11. 14 CFR 221.204 - Adoption of provisions of one carrier by another carrier.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Adoption of provisions of one carrier by another carrier. 221.204 Section 221.204 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF... Adoption of provisions of one carrier by another carrier. When one carrier adopts the tariffs of...

  12. 14 CFR 221.204 - Adoption of provisions of one carrier by another carrier.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Adoption of provisions of one carrier by another carrier. 221.204 Section 221.204 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF... Adoption of provisions of one carrier by another carrier. When one carrier adopts the tariffs of...

  13. 14 CFR 221.204 - Adoption of provisions of one carrier by another carrier.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Adoption of provisions of one carrier by another carrier. 221.204 Section 221.204 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF... Adoption of provisions of one carrier by another carrier. When one carrier adopts the tariffs of...

  14. 14 CFR 221.204 - Adoption of provisions of one carrier by another carrier.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Adoption of provisions of one carrier by another carrier. 221.204 Section 221.204 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF... Adoption of provisions of one carrier by another carrier. When one carrier adopts the tariffs of...

  15. 14 CFR 221.204 - Adoption of provisions of one carrier by another carrier.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Adoption of provisions of one carrier by another carrier. 221.204 Section 221.204 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF... Adoption of provisions of one carrier by another carrier. When one carrier adopts the tariffs of...

  16. 14 CFR 399.82 - Passing off of carrier identity by affiliation between carriers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Passing off of carrier identity by... Relating to Enforcement § 399.82 Passing off of carrier identity by affiliation between carriers. (a... points served by both carriers should preserve the identity of the individual carriers; (5) Where...

  17. 14 CFR 399.82 - Passing off of carrier identity by affiliation between carriers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Passing off of carrier identity by... Relating to Enforcement § 399.82 Passing off of carrier identity by affiliation between carriers. (a... points served by both carriers should preserve the identity of the individual carriers; (5) Where...

  18. 14 CFR 399.82 - Passing off of carrier identity by affiliation between carriers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Passing off of carrier identity by... Relating to Enforcement § 399.82 Passing off of carrier identity by affiliation between carriers. (a... points served by both carriers should preserve the identity of the individual carriers; (5) Where...

  19. 14 CFR 399.82 - Passing off of carrier identity by affiliation between carriers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Passing off of carrier identity by... Relating to Enforcement § 399.82 Passing off of carrier identity by affiliation between carriers. (a... points served by both carriers should preserve the identity of the individual carriers; (5) Where...

  20. 14 CFR 380.11 - Payment to direct air carrier(s).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... carrier(s). Except for air taxi operators and commuter air carriers (which are governed by 14 CFR 298.38) and Canadian charter air taxi operators (which are governed by 14 CFR 294.32), the direct air carrier(s) shall be paid in full for the cost of the charter transportation (for both legs, if a...

  1. 75 FR 50797 - Motor Carrier Safety Advisory Committee Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-17

    ... Federal Motor Carrier Safety Administration Motor Carrier Safety Advisory Committee Public Meeting AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT. ACTION: Notice of Motor Carrier Safety Advisory Committee Meeting. SUMMARY: FMCSA announces that its Motor Carrier Safety Advisory Committee (MCSAC)...

  2. 75 FR 72863 - Motor Carrier Safety Advisory Committee Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-26

    ... Federal Motor Carrier Safety Administration Motor Carrier Safety Advisory Committee Public Meeting AGENCY: Federal Motor Carrier Safety Administration, DOT. ACTION: Notice of Motor Carrier Safety Advisory Committee Meeting. SUMMARY: FMCSA announces that the Agency's Motor Carrier Safety Advisory Committee...

  3. 76 FR 12214 - Motor Carrier Safety Advisory Committee Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-04

    ... Federal Motor Carrier Safety Administration Motor Carrier Safety Advisory Committee Public Meeting AGENCY: Federal Motor Carrier Safety Administration, DOT. ACTION: Notice: Announcement of Motor Carrier Safety Advisory Committee meeting; request for comment. SUMMARY: The Federal Motor Carrier Safety...

  4. Whey drying on porous carriers

    SciTech Connect

    Mitura, E.; Kaminski, W.

    1996-05-01

    Whey is treated very often as a waste which pollutes the natural environment. Whey which is a valuable source of protein, lacrose, vitamins and mineral salts should be utilized completely. The present paper is a proposal of whey drying on porous carriers. It is proved experimentally that the proposed drying method guarantees good product quality.

  5. Preparation of Sm-doped ceria (SDC) nanowires and tubes by gas-liquid co-precipitation at room temperature

    SciTech Connect

    Gu Lina Meng Guangyao

    2008-06-03

    Sm-doped cerium dioxide (SDC) with fcc structure was formed using a gas-liquid chemical co-precipitation process at room temperature. Morphology and structure of the as-prepared samples were characterized using TG, XRD, TEM, HRTEM and SAED techniques. Under our specific experimental conditions, two kinds of 1D nano-structures SDC have been mainly obtained. SDC nanowires are 0.3-1.2 {mu}m in lengths and 5-20 nm in diameters. SDC nanotubes have outer diameters in 10-40 nm with lengths up to 2 {mu}m. The as-prepared SDC shows very strong UV absorption ability and the maximum absorption peak redshifts compared with that of SDC nanoparticles.

  6. Optical and structural properties of Fe-doped SnO2 nanoparticles prepared by co-precipitation method

    NASA Astrophysics Data System (ADS)

    Kaur, Navneet; Abhinav, Singh, Gurwinder Pal; Singh, Vishal; Kumar, Sacheen; Kumar, Dinesh

    2016-05-01

    Today nanomaterials plays important role in every field, due to their unique mechanical, chemical and electrical properties which are completely different from the bulk materials. With reduction in the size of material its properties are dynamically changed. Semiconductor materials are widely used in electronic devices but in the field of optoelectronic these materials have some limitations. Tin oxide could be the material which could be used in these applications without limitations. Doped Tin Oxide is an oxygen deficient material which could be beneficial for transparent conducting oxide. Iron doped SnO2 prepared by co-precipitation method. Studies on structural properties of undoped and doped SnO2 were done by X-ray diffraction. The XRD results have shown that the size of the nanoparticles decreases with Fe doping down to 53nm. Optical Properties were studied by UV-visible spectroscopy. Band gap was found to decrease with increase in iron content in samples.

  7. Room temperature ferromagnetism and luminescent behavior of Ni doped ZnO nanoparticles prepared by coprecipitation method

    NASA Astrophysics Data System (ADS)

    Arora, Deepawali; Ashokan, K.; Mahajan, Aman; Kaur, Parvinder; Singh, Gurinder Pal; Kumar, Sunil; Singh, D. P.

    2016-05-01

    The samples of Zn1-xNixO (x= 0.00 and 0.05) were prepared using coprecipitation method and annealed at different temperatures. The effect of Ni ion substitution on the structural and optical properties has been studied using X-ray Diffraction, UV-Visible, Photoluminescence and Magnetic measurements. XRD measurements demonstrate that all the prepared samples are wurtzite polycrystalline single phase in nature, ruling out the presence of any secondary phase formation. Ultraviolet visible measurements showed a decrease in band gap with the increase in annealing temperature and doping concentration. The PL data shows the red shift in all the samples and luminescence quenching with Ni doping. Compared to undoped ZnO, Ni doped ZnO showed room temperature ferromagnetism

  8. Mixed magnetic phases in Co{sub 3}O{sub 4} nanoparticles synthesized by co-precipitation method

    SciTech Connect

    Rani, Stuti; Varma, G. D.; Sharma, Yogesh

    2014-04-24

    In the present manuscript, Co{sub 3}O{sub 4} nanoparticles have been synthesized with the help of co-precipitation method and studied the structural, optical and magnetic properties. X ray diffraction analysis of the synthesized samples reveals the formation of single phase cubic spinel structure with the space group Fd-3m. FESEM and TEM results indicate the formation of nano-sized particles. The optical measurement reveals the two band gaps ∼2.77 and 1.67 eV in the sample. Magnetic measurement shows weak ferromagnetic interaction in Co{sub 3}O{sub 4} along with usual paramagnetic nature at room temperature. However, at low temperatures the sample shows antiferromagnetic interaction. The correlation between the structural and observed magnetic and optical properties of Co{sub 3}O{sub 4} nanoparticles will be described and discussed in this paper.

  9. A new coprecipitation methodology with lutetium hydroxide for preconcentration of heavy metal ions in herbal plant samples.

    PubMed

    Soylak, Mustafa; Murat, Ipek

    2014-01-01

    A new coprecipitation methodology that used lutetium hydroxide as a precipitant for Cu(II), Pb(II), Mn(II), Co(II), Cd(II), Fe(III), and Ni(II) ions in herbal plant and water samples for analysis by atomic absorption spectrometry has been investigated. The parameters such as pH, amount of lutetium, and volume of aqueous sample were optimized for the recovery of these seven metals. The effects of concomitant ions on the separation-preconcentration of analytes were also checked. The validation of the procedure was checked with addition recovery tests and analysis of Standard Reference Material 1570a-Trace Elements in Spinach Leaves and TMDA-70 fortified lake water Certified Reference Material. The LODs for analyte ions were in the range of 1.7-7.2 microg/L. The application of the present procedure was successfully performed for the analysis of analyte contents of herbal plant samples from Turkey.

  10. Synthesis of Mn1-xZnxFe2O4 ferrite powder by co-precipitation method

    NASA Astrophysics Data System (ADS)

    Irfan, Salma; Ajaz-un-Nabi, M.; Jamil, Yasir; Amin, Nasir

    2014-06-01

    Ferrimagnetic substances referred to as ferrites are ionic crystals whose chemical composition is of the form XFe2 O4 where X signifies a divalent metal. Magnetic Nano sized ferrites have found a significant potential in many applications, such as magnetic recording media, Ferro fluids and radar absorbing coating. Ferrites are widely used in many industrial applications due to their spontaneous magnetization. Soft ferrites of Mn-Zn, Ni-Zn and Mg-Mn are well known for their high magnetic permeability. In the present research work we have prepared fine Mn1-xZnxFe2O4 ferrite powder with varying x concentrations (0.25-0.75) by metal chloride precursors through a co-precipitation technique by pipette drop method using aqueous NaOH solution for comparing their spontaneous magnetization and particle size. The co-precipitation technique is a high way to produce chemically homogeneous powder with fine particle size in nanometers (22.5nm-74.5nm).The effect of x-concentration on the particle size of the Mn(1-x) Zn(x) ferrite has been discussed on the basis of XRD. The crystalline phases have been identified by X-ray diffraction with Cu-Kα radiations. The XRD patterns have verified that the specimen has spinal type structure. The observable peaks are broad since the size of the particles is small. We have concluded that at constants temperature particle size increases with increasing x-concentrations. Effect of different concentrations of x (Zn+2) on the spontaneous magnetization of different Mn(1-x) Zn(x) Fe2O4 sample is determined. We have reached the conclusion that all the samples of Mn(1-x) Zn(x) Fe2 O4 ferrites were magnetic either of low or high magnetization. The maximum spontaneous magnetization and minimum particle size is obtained at x=0.25 (at digestion temperature=65°C).

  11. Bacterially Induced Calcite Precipitation and Strontium Co-Precipitation under Flow Conditions in a Porous Media System

    NASA Astrophysics Data System (ADS)

    Gerlach, R.; Mitchell, A. C.; Schultz, L.; Cunningham, A.

    2009-12-01

    The process of in situ carbonate mineral formation has implications in many environmental applications, including, but not limited to aquifer decontamination, enhancement of soil stability, and carbon capture and storage (CCS). The high stability of carbonates and the potential for co-precipitation of contaminants within carbonates are attractive attributes for several potential engineering applications. Ureolytic precipitation of calcium and strontium carbonates by Sporosarcina pasteurii was examined in two-dimensional flat plate porous media reactors. Complete reactor plugging due to biofilm formation and calcium carbonate precipitation was achieved in Sr-free systems after 14 hours and in Sr-inclusive systems after 15 hours. Comparison of the reactor influent and effluent after 11 hours indicated that Ca2+ concentrations in the Sr-free reactor effluent were reduced to approximately 0.48% of the influent concentration while the Ca2+ and Sr2+ concentrations of the Sr-inclusive effluent were reduced to 0.64% and 2.34% of the influent concentration indicating a slight inhibitory effect of strontium on calcium carbonate precipitation . Despite this slight inhibition, more than 98% of the Ca2+ entering the reactors was precipitated. Calcite was identified as the main mineral formed and a larger mean crystal size and density were observed near the reactor influent. Homogenous partition coefficients calculated from extracted precipitates suggest higher Sr2+ partitioning near the inlet region, where higher precipitation kinetics exist. Results confirm the possibility of effective calcite-based co-precipitation of Sr2+ under flow conditions and contributes towards the development of field-scale calcium carbonate mineral-based immobilization strategies.

  12. Preparation of ceria-zirconia by modified coprecipitation method and its supported Pd-only three-way catalyst.

    PubMed

    Lan, Li; Chen, Shanhu; Cao, Yi; Zhao, Ming; Gong, Maochu; Chen, Yaoqiang

    2015-07-15

    A CeO2-ZrO2 compound with mixed phase composition (CZ4) was prepared by modified co-precipitation method, and for comparison, single-phase Ce(0.2)Zr(0.8)O2, Ce(0.5)Zr(0.5)O2 and Ce(0.8)Zr(0.2)O2 were synthesized via simultaneous co-precipitation method. The textural, structural and redox properties, together with the catalytic performance of the supported Pd-only three-way catalysts were investigated systematically. The results revealed that the generation of numerous interface sites in Pd/CZ4 due to its mixed phase composition (as confirmed by TEM observation) had a positive influence on modifying its structural, redox properties and thermal stability. The XRD and Raman results revealed that the highest structural stability was obtained by Pd/CZ4 with negligible lattice variation and slightest grain growth after aging treatment. The XPS analysis demonstrated that the compositional heterogeneity of Pd/CZ4 could facilitate the formation of Ce(3+), and was beneficial to preserve high dispersion of Pd as well as maintain Pd at a more oxidized state. The H2-TPR and oxygen storage capacity measurements indicated that Pd/CZ4 possessed highest reduction ability as well as largest oxygen storage capacity regardless of thermal aging treatment. And consequently Pd/CZ4 exhibited improved three-way catalytic activity compared with the catalysts supported on single-phase Ce(x)Zr(1-x)O2 both before and after thermal aging treatment.

  13. Bacterially Induced Calcite Precipitation and Strontium Co-Precipitation under Flow Conditions in a Porous Media System

    NASA Astrophysics Data System (ADS)

    Gerlach, Robin; Mitchell, Andrew C.; Schultz, Logan N.; Cunningham, Al B.

    2010-05-01

    The process of in situ carbonate mineral formation has implications in many environmental applications, including, but not limited to aquifer decontamination, enhancement of soil stability, and carbon capture and storage (CCS). The high stability of carbonates and the potential for co-precipitation of contaminants within carbonates are attractive attributes for several potential engineering applications. Ureolytic precipitation of calcium and strontium carbonates by Sporosarcina pasteurii was examined in two-dimensional flat plate porous media reactors. Complete reactor plugging due to biofilm formation and calcium carbonate precipitation was achieved in Sr-free systems after 14 hours and in Sr-inclusive systems after 15 hours. Comparison of the reactor influent and effluent after 11 hours indicated that Ca2+ concentrations in the Sr-free reactor effluent were reduced to approximately 0.48% of the influent concentration while the Ca2+ and Sr2+ concentrations of the Sr-inclusive effluent were reduced to 0.64% and 2.34% of the influent concentration indicating a slight inhibitory effect of strontium on calcium carbonate precipitation . Despite this slight inhibition, more than 98% of the Ca2+ entering the reactors was precipitated. Calcite was identified as the main mineral formed and a larger mean crystal size and density were observed near the reactor influent. Homogenous partition coefficients calculated from extracted precipitates suggest higher Sr2+ partitioning near the inlet region, where higher precipitation kinetics exist. Results confirm the possibility of effective calcite-based co-precipitation of Sr2+ under flow conditions and contributes towards the development of field-scale calcium carbonate mineral-based immobilization strategies.

  14. Experimental study and modeling of the U(VI)-Fe(OH) 3 surface precipitation/coprecipitation equilibria

    NASA Astrophysics Data System (ADS)

    Bruno, J.; De Pablo, J.; Duro, L.; Figuerola, E.

    1995-10-01

    The kinetics and thermodynamics of the coprecipitation of U(VI) with Fe(III) oxyhydroxides have been studied under controlled laboratory conditions, by means of chemical solution and spectroscopic techniques. The monitoring of uranium concentration after the simultaneous precipitation of Fe(III) and U(VI) from a homogeneous solution indicates that a fast and quantitative sorption of uranium on the Fe(III) oxyhydroxide surface occurs. This is followed by the gradual release of a part of the uranium from the solid phase which can be attributed to a structural rearrangement of the solid surface. Equilibrium uranium concentrations are attained after fifteen days of contact. Several surface complexation models are tested to model the behavior of the system and a simple thermodynamic approach has been proposed in order to describe this post-adsorption phenomena. A conditional solubility constant for the uranium limiting phase is defined as K SO∗ = K SO · χ , where KSO is the solubility constant for the individual solid phase and χ stands for the molar fraction of the uranium in the bulk of the solid. Treatment of data obtained at different U(VI) to Fe(III) initial concentration ratios and at fixed pH value has allowed us to propose the surface precipitation of schoepite on Fe(III) oxyhydroxide as the uranium solubility limiting phase. It has been shown that the behavior of the system can be equally described by both surface complexation and conditional solubility approaches. However, the surface complexation modelling requires the knowledge of the surface properties of the solid. The much simpler coprecipitation approach is only based on mass balances and stoichiometric relationships, which can be a useful predictive tool for the trace metal concentrations in natural systems.

  15. Application of internal standardization to rapid coprecipitation technique using lanthanum phosphate for flame atomic absorption spectrometric determination of iron and lead.

    PubMed

    Kagaya, Shigehiro; Malek, Zanariah Abdul; Araki, Yasuko; Hasegawa, Kiyoshi

    2002-08-01

    By applying an internal standardization, we could use a rapid coprecipitation technique using lanthanum phosphate as a coprecipitant for preconcentration of iron(III) and lead in their flame atomic absorption spectrometric determination. Indium as an internal standard was added to the initial sample solution together with lanthanum and phosphoric acid; the coprecipitation of iron(III) and lead was then carried out at pH about 3. After measuring the atomic absorbances of iron, lead, and indium in the final sample solution, we determined the contents of iron(III) and lead in the original sample solution by using the internal standardization with indium. In this method, complete collection of the precipitate was not required after the coprecipitation of iron(III), lead, and indium, because the ratio of the recovery of iron(III) or lead to that of indium was almost constant regardless of the recovery of the precipitate. This method was simple and rapid, and was available for the determination of 2-300 micrograms L-1 of iron(III) and 5-400 micrograms L-1 of lead in some water samples.

  16. Fabrication of highly-specific SERS substrates by co-precipitation of functional nanomaterials during the self-sedimentation of silver nanowires into a nanoporous film.

    PubMed

    Liu, Rui; Sun, Jie-fang; Cao, Dong; Zhang, Li-qiang; Liu, Jing-fu; Jiang, Gui-bin

    2015-01-25

    In this report, we propose and demonstrate the fabrication of a highly-specific SERS substrate, which was achieved by the co-precipitation of functional materials, such as nanosorbents and nanocatalysts, into Ag nanoporous films. Based on the nanostructures developed, we performed the ultrasensitive detection of arsenic ions by SERS and monitored the catalyzed reactions using real-time SERS.

  17. Reduction of ferrihydrite with adsorbed and coprecipitated organic matter: microbial reduction by Geobacter bremensis vs. abiotic reduction by Na-dithionite

    NASA Astrophysics Data System (ADS)

    Eusterhues, K.; Hädrich, A.; Neidhardt, J.; Küsel, K.; Keller, T. F.; Jandt, K. D.; Totsche, K. U.

    2014-09-01

    Ferrihydrite is a widespread poorly crystalline Fe oxide which becomes easily coated by natural organic matter in the environment. This mineral-bound organic matter entirely changes the mineral surface properties and therefore the reactivity of the original mineral. Here, we investigated 2-line ferrihydrite, ferrihydrite with adsorbed organic matter, and ferrihydrite coprecipitated with organic matter for microbial and abiotic reduction of Fe(III). Ferrihydrite-organic matter associations with different organic matter loadings were reduced either by Geobacter bremensis or abiotically by Na-dithionite. Both types of experiments showed decreasing initial Fe-reduction rates and decreasing degrees of reduction with increasing amounts of mineral-bound organic matter. At similar organic matter loadings, coprecipitated ferrihydrites were more reactive than ferrihydrites with adsorbed organic matter. The difference can be explained by the smaller crystal size and poor crystallinity of such coprecipitates. At small organic matter loadings the poor crystallinity of coprecipitates led to even faster Fe-reduction rates than found for pure ferrihydrite. The amount of mineral-bound organic matter also affected the formation of secondary minerals: goethite was only found after reduction of organic matter-free ferrihydrite and siderite was only detected when ferrihydrites with relatively low amounts of mineral-bound organic matter were reduced. We conclude that direct contact of G. bremensis to the Fe oxide mineral surface was inhibited by attached organic matter. Consequently, mineral-bound organic matter shall be taken into account as a factor in slowing down reductive dissolution.

  18. Aluminum Coprecipitates with Fe (hydr)oxides: Does Isomorphous Substitution of Al3plus for Fe3plus in Goethite Occur

    SciTech Connect

    E Bazilevskaya; D Archibald; M Aryanpour; J Kubicki; C Martinez

    2011-12-31

    Iron (hydr)oxides are common in natural environments and typically contain large amounts of impurities, presumably the result of coprecipitation processes. Coprecipitation of Al with Fe (hydr)oxides occurs, for example, during alternating reduction-oxidation cycles that promote dissolution of Fe from Fe-containing phases and its re-precipitation as Fe-Al (hydr)oxides. We used chemical and spectroscopic analyses to study the formation and transformation of Al coprecipitates with Fe (hydr)oxides. In addition, periodic density functional theory (DFT) computations were performed to assess the structural and energetic effects of isolated or clustered Al atoms at 8 and 25 mol% Al substitution in the goethite structure. Coprecipitates were synthesized by raising the pH of dilute homogeneous solutions containing a range of Fe and Al concentrations (100% Fe to 100% Al) to 5. The formation of ferrihydrite in initial suspensions with {<=}20 mol% Al, and of ferrihydrite and gibbsite in initial suspensions with {>=}25 mol% Al was confirmed by infrared spectroscopic and synchrotron-based X-ray diffraction analyses. While base titrations showed a buffer region that corresponded to the hydrolysis of Fe in initial solutions with {<=}25 mol% Al, all of the Al present in these solutions was retained by the solid phases at pH 5, thus indicating Al coprecipitation with the primary Fe hydroxide precipitate. In contrast, two buffer regions were observed in solutions with 30 mol% Al (at pH {approx}2.25 for Fe{sup 3+} and at pH {approx}4 for Al{sup 3+}), suggesting the formation of Fe and Al (hydr)oxides as two separate phases. The Al content of initial coprecipitates influenced the extent of ferrihydrite transformation and of its transformation products as indicated by the presence of goethite, hematite and/or ferrihydrite in aged suspensions. DFT experiments showed that: (i) optimized unit cell parameters for Al-substituted goethites (8 and 25 Mol% Al) in clustered arrangement (i.e., the

  19. 14 CFR 271.4 - Carrier costs.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... place will be evaluated: (1) For costs attributable to the carrier's flying operations (direct expenses... altitude at which the carrier must fly to the designated hub; and (v) Other operational elements...

  20. Natural Carriers for siRNA Delivery.

    PubMed

    Karunaratne, D Nedra; Jafari, Mousa; Ranatunga, R J K Udayana; Siriwardhana, Asitha

    2015-01-01

    This review is based on carriers of natural origin such as polysaccharides, proteins, and cell derived entities which have been used for delivery of siRNA. To realize the therapeutic potential of a delivery system, the role of the carrier is of utmost importance. Historical aspects of viral vectors, the first carriers of genes are briefly outlined. Chitosan, one of the extensively experimented carriers, alginates and other polysaccharides have shown success in siRNA delivery. Peptides of natural origin and mimics thereof have emerged as another versatile carrier. Exosomes and mini cells of cellular origin are the newest entrants to the area of siRNA delivery and probably the closest one can get to a natural carrier. In many of the carriers, modifications have provided better efficiency in delivery. The salient features of the carriers and their advantages and disadvantages are also reviewed.

  1. Protein carriers of conjugate vaccines

    PubMed Central

    Pichichero, Michael E

    2013-01-01

    The immunogenicity of polysaccharides as human vaccines was enhanced by coupling to protein carriers. Conjugation transformed the T cell-independent polysaccharide vaccines of the past to T cell-dependent antigenic vaccines that were much more immunogenic and launched a renaissance in vaccinology. This review discusses the conjugate vaccines for prevention of infections caused by Hemophilus influenzae type b, Streptococcus pneumoniae, and Neisseria meningitidis. Specifically, the characteristics of the proteins used in the construction of the vaccines including CRM, tetanus toxoid, diphtheria toxoid, Neisseria meningitidis outer membrane complex, and Hemophilus influenzae protein D are discussed. The studies that established differences among and key features of conjugate vaccines including immunologic memory induction, reduction of nasopharyngeal colonization and herd immunity, and antibody avidity and avidity maturation are presented. Studies of dose, schedule, response to boosters, of single protein carriers with single and multiple polysaccharides, of multiple protein carriers with multiple polysaccharides and conjugate vaccines administered concurrently with other vaccines are discussed along with undesirable consequences of conjugate vaccines. The clear benefits of conjugate vaccines in improving the protective responses of the immature immune systems of young infants and the senescent immune systems of the elderly have been made clear and opened the way to development of additional vaccines using this technology for future vaccine products. PMID:23955057

  2. New mitochondrial carriers: an overview.

    PubMed

    Arco, A Del; Satrústegui, J

    2005-10-01

    The transport of metabolites, nucleotides and cofactors across the mitochondrial inner membrane is performed by members of mitochondrial carrier family (MCF). These proteins share marked structural features that have made feasible the functional characterization of numerous MCs in the last years. The MCs responsible for transport activities in mitochondria known for decades such as glutamate uptake or ATP-Mg/Pi exchange have recently been identified as well as novel carriers such as those involved in S-adenosylmethionine or thiamine pyrophosphate uptake. Here, after a brief review of the novel data on structural characteristics and import mechanisms of MCF members, we present an exhaustive compilation of human MC sequences, including previously characterized carriers, together with their respective Saccharomyces cerevisiae orthologues, ordered according to the phylogenetic analysis of el Moualij and co-workers [Yeast (1997) 13: 573-581]. We have detected the existence of at least 49 human MC sequences, including those of yet unknown function. An overview of novel MCF members functionally characterized in recent years in mammals and in yeast genomes is presented.

  3. Spacelab carrier complement thermal design and performance

    NASA Astrophysics Data System (ADS)

    Bancroft, S.; Key, R.; Kittredge, S.

    1992-07-01

    The present discussion of the Spacelab carrier complement, which encompasses a Module Carrier, a Module-Pallet Carrier, and a Multiplexer/Demultiplexer Pallet, gives attention to both active and passive thermal performance capabilities, and presents ground testing and analytical results obtained to date. An account is given of the prospective use of a Spacelab Multipurpose Experiment Support Structure.

  4. 8 CFR 217.6 - Carrier agreements.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Carrier agreements. 217.6 Section 217.6 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS VISA WAIVER PROGRAM § 217... may notify a carrier of the existence of a basis for termination of a carrier agreement under...

  5. 8 CFR 217.6 - Carrier agreements.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Carrier agreements. 217.6 Section 217.6 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS VISA WAIVER PROGRAM § 217... may notify a carrier of the existence of a basis for termination of a carrier agreement under...

  6. 8 CFR 217.6 - Carrier agreements.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Carrier agreements. 217.6 Section 217.6 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS VISA WAIVER PROGRAM § 217... may notify a carrier of the existence of a basis for termination of a carrier agreement under...

  7. 8 CFR 217.6 - Carrier agreements.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Carrier agreements. 217.6 Section 217.6 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS VISA WAIVER PROGRAM § 217... may notify a carrier of the existence of a basis for termination of a carrier agreement under...

  8. 8 CFR 217.6 - Carrier agreements.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Carrier agreements. 217.6 Section 217.6 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS VISA WAIVER PROGRAM § 217... may notify a carrier of the existence of a basis for termination of a carrier agreement under...

  9. 49 CFR 1139.21 - Study carriers.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... OF TRANSPORTATION RULES OF PRACTICE PROCEDURES IN MOTOR CARRIER REVENUE PROCEEDINGS Intercity Bus... calendar year, the dollar amounts of total system operating revenues for each such carrier shall be arrayed... total issue traffic revenue is to its total system revenues, and the percent that each carrier's...

  10. Responsible implementation of expanded carrier screening

    PubMed Central

    Henneman, Lidewij; Borry, Pascal; Chokoshvili, Davit; Cornel, Martina C; van El, Carla G; Forzano, Francesca; Hall, Alison; Howard, Heidi C; Janssens, Sandra; Kayserili, Hülya; Lakeman, Phillis; Lucassen, Anneke; Metcalfe, Sylvia A; Vidmar, Lovro; de Wert, Guido; Dondorp, Wybo J; Peterlin, Borut

    2016-01-01

    This document of the European Society of Human Genetics contains recommendations regarding responsible implementation of expanded carrier screening. Carrier screening is defined here as the detection of carrier status of recessive diseases in couples or persons who do not have an a priori increased risk of being a carrier based on their or their partners' personal or family history. Expanded carrier screening offers carrier screening for multiple autosomal and X-linked recessive disorders, facilitated by new genetic testing technologies, and allows testing of individuals regardless of ancestry or geographic origin. Carrier screening aims to identify couples who have an increased risk of having an affected child in order to facilitate informed reproductive decision making. In previous decades, carrier screening was typically performed for one or few relatively common recessive disorders associated with significant morbidity, reduced life-expectancy and often because of a considerable higher carrier frequency in a specific population for certain diseases. New genetic testing technologies enable the expansion of screening to multiple conditions, genes or sequence variants. Expanded carrier screening panels that have been introduced to date have been advertised and offered to health care professionals and the public on a commercial basis. This document discusses the challenges that expanded carrier screening might pose in the context of the lessons learnt from decades of population-based carrier screening and in the context of existing screening criteria. It aims to contribute to the public and professional discussion and to arrive at better clinical and laboratory practice guidelines. PMID:26980105

  11. 14 CFR 221.2 - Carrier's duty.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... REGULATIONS TARIFFS General § 221.2 Carrier's duty. (a) Must file tariffs. (1) Except as provided in paragraph... carrier or foreign air carrier, when through service and through rates shall have been established, and... collect or receive a greater or less or different compensation for foreign air transportation or for...

  12. Spacelab carrier complement thermal design and performance

    NASA Technical Reports Server (NTRS)

    Bancroft, S.; Key, R.; Kittredge, S.

    1992-01-01

    The present discussion of the Spacelab carrier complement, which encompasses a Module Carrier, a Module-Pallet Carrier, and a Multiplexer/Demultiplexer Pallet, gives attention to both active and passive thermal performance capabilities, and presents ground testing and analytical results obtained to date. An account is given of the prospective use of a Spacelab Multipurpose Experiment Support Structure.

  13. 49 CFR 1139.21 - Study carriers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 8 2013-10-01 2013-10-01 false Study carriers. 1139.21 Section 1139.21... Industry § 1139.21 Study carriers. (a) For the purposes of this proceeding the “study carriers” shall... and/or charges. (b) To corroborate the selection of the above study carriers, and to provide a...

  14. 49 CFR 1139.21 - Study carriers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 8 2012-10-01 2012-10-01 false Study carriers. 1139.21 Section 1139.21... Industry § 1139.21 Study carriers. (a) For the purposes of this proceeding the “study carriers” shall... and/or charges. (b) To corroborate the selection of the above study carriers, and to provide a...

  15. 49 CFR 376.22 - Exemption for private carrier leasing and leasing between authorized carriers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Exemption for private carrier leasing and leasing... MOTOR CARRIER SAFETY REGULATIONS LEASE AND INTERCHANGE OF VEHICLES Exemptions for the Leasing Regulations § 376.22 Exemption for private carrier leasing and leasing between authorized carriers....

  16. Non-permeable substrate carrier for electroplating

    DOEpatents

    Abas, Emmanuel Chua; Chen, Chen-An; Ma, Diana Xiaobing; Ganti, Kalyana Bhargava

    2012-11-27

    One embodiment relates to a substrate carrier for use in electroplating a plurality of substrates. The substrate carrier comprises a non-conductive carrier body on which the substrates are to be held. Electrically-conductive lines are embedded within the carrier body, and a plurality of contact clips are coupled to the electrically-conductive lines embedded within the carrier body. The contact clips hold the substrates in place and electrically couple the substrates to the electrically-conductive lines. The non-conductive carrier body is continuous so as to be impermeable to flow of electroplating solution through the non-conductive carrier body. Other embodiments, aspects and features are also disclosed.

  17. Non-permeable substrate carrier for electroplating

    SciTech Connect

    Abas, Emmanuel Chua; Chen, Chen-an; Ma, Diana Xiaobing; Ganti, Kalyana; Divino, Edmundo Anida; Ermita, Jake Randal G.; Capulong, Jose Francisco S.; Castillo, Arnold Villamor

    2015-12-29

    One embodiment relates to a substrate carrier for use in electroplating a plurality of substrates. The substrate carrier comprises a non-conductive carrier body on which the substrates are to be held. Electrically-conductive lines are embedded within the carrier body, and a plurality of contact clips are coupled to the electrically-conductive lines embedded within the carrier body. The contact clips hold the substrates in place and electrically couple the substrates to the electrically-conductive lines. The non-conductive carrier body is continuous so as to be impermeable to flow of electroplating solution through the non-conductive carrier body. Other embodiments, aspects and features are also disclosed.

  18. Biocheese: A Food Probiotic Carrier

    PubMed Central

    Castro, J. M.; Tornadijo, M. E.; Fresno, J. M.; Sandoval, H.

    2015-01-01

    This review describes some aspects related to the technological barriers encountered in the development and stability of probiotic cheeses. Aspects concerning the viability of probiotic cultures in this matrix are discussed and the potential of cheese as a biofunctional food carrier is analyzed, outlying some points related to health and safety. In general, the manufacture of probiotic cheese should have little change when compared with the elaboration of cheese in the traditional way. The physicochemical and technological parameters influencing the quality of these products have also to be measured so as to obtain a process optimization. PMID:25802862

  19. Biocheese: a food probiotic carrier.

    PubMed

    Castro, J M; Tornadijo, M E; Fresno, J M; Sandoval, H

    2015-01-01

    This review describes some aspects related to the technological barriers encountered in the development and stability of probiotic cheeses. Aspects concerning the viability of probiotic cultures in this matrix are discussed and the potential of cheese as a biofunctional food carrier is analyzed, outlying some points related to health and safety. In general, the manufacture of probiotic cheese should have little change when compared with the elaboration of cheese in the traditional way. The physicochemical and technological parameters influencing the quality of these products have also to be measured so as to obtain a process optimization. PMID:25802862

  20. 78 FR 66801 - Motor Carrier Safety Advisory Committee; Charter Renewal

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-06

    ... Federal Motor Carrier Safety Administration Motor Carrier Safety Advisory Committee; Charter Renewal AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT. ACTION: Announcement of advisory... Committee that provides the Agency with advice and recommendations on motor carrier safety programs...

  1. Carrier detection in xeroderma pigmentosum

    SciTech Connect

    Parshad, R.; Sanford, K.K.; Kraemer, K.H.; Jones, G.M.; Tarone, R.E. )

    1990-01-01

    We were able to detect clinically normal carriers of xeroderma pigmentosum (XP) genes with coded samples of either peripheral blood lymphocytes or skin fibroblasts, using a cytogenetic assay shown previously to detect individuals with cancer-prone genetic disorders. Metaphase cells of phytohemagglutinin-stimulated T-lymphocytes from eight individuals who are obligate heterozygotes for XP were compared with those from nine normal controls at 1.3, 2.3, and 3.3 h after x-irradiation (58 R) during the G2 phase of the cell cycle. Lymphocytes from the XP heterozygotes had twofold higher frequencies of chromatid breaks or chromatid gaps than normal (P less than 10(-5)) when fixed at 2.3 or 3.3 h after irradiation. Lymphocytes from six XP homozygotes had frequencies of breaks and gaps threefold higher than normal. Skin fibroblasts from an additional obligate XP heterozygote, when fixed approximately 2 h after x-irradiation (68 R), had a twofold higher frequency of chromatid breaks and a fourfold higher frequency of gaps than fibroblasts from a normal control. This frequency of aberrations in cells from the XP heterozygote was approximately half that observed in the XP homozygote. The elevated frequencies of chromatid breaks and gaps after G2 phase x-irradiation may provide the basis of a test for identifying carriers of the XP gene(s) within known XP families.

  2. Femtosecond carrier dynamics in graphite

    NASA Astrophysics Data System (ADS)

    Seibert, K.; Cho, G. C.; Kütt, W.; Kurz, H.; Reitze, D. H.; Dadap, J. I.; Ahn, H.; Downer, M. C.; Malvezzi, A. M.

    1990-08-01

    We present a comprehensive report of pump-probe reflectivity and transmission measurements on highly oriented pyrolytic graphite with 50 fs time resolution. The experiments trace the generation, relaxation, and recombination of nonequilibrium carriers in a quasi-two-dimensional semimetallic solid over a wide range of experimental parameters. The fluence of excitation at hν=2.0 eV was varied between 10-6 and 10-2 J/cm2, below the threshold for optical damage, while probe pulses in the photon energy range 1.5carriers cool and recombine in less than 1 ps. Later dynamics reflect the generation and diffusion of heat in the lattice, and are consistent with previous picosecond reflectivity measurements.

  3. Characterization and in vivo evaluation of chitosan-hydroxyapatite bone scaffolds made by one step coprecipitation method.

    PubMed

    Danilchenko, Sergei N; Kalinkevich, Oksana V; Pogorelov, Maksim V; Kalinkevich, Aleksei N; Sklyar, Anatoly M; Kalinichenko, Tatyana G; Ilyashenko, Vyacheslav Y; Starikov, Vadim V; Bumeyster, Valentina I; Sikora, Vitaly Z; Sukhodub, Leonid F

    2011-03-15

    Chitosan/hydroxyapatite scaffolds could be used for bone regeneration in case the application of auto- or allografts is impossible. The objective of the present work was to characterize and study in vivo biodegradation of simple chitosan/hydroxyapatite scaffolds. For this purpose, a series of chitosan/hydroxyapatite composites has been synthesized in aqueous medium from chitosan solution and soluble precursor salts by a one step coprecipitation method. A study of in vivo behavior of the materials was then performed using model linear rats. Cylindrical-shaped rods made of the chitosan/hydroxyapatite composite material were implanted into tibial bones of the rats. After 5, 10, 15, and 24 days of implantation, histological and histo-morphometric analyses of decalcified specimens were performed to evaluate the stages of biodegradation processes. Calcified specimens were examined by scanning electron microscopy with X-ray microanalysis to compare elemental composition and morphological characteristics of the implant and the bone during integration. Porous chitosan/hydroxyapatite scaffolds have shown osteoconductive properties and have been replaced in the in vivo experiments by newly formed bone tissue. PMID:21268238

  4. Effects of the synthesis temperature on the crystalline structure and the magnetic properties of cobalt ferrite nanoparticles prepared via coprecipitation

    NASA Astrophysics Data System (ADS)

    Hutamaningtyas, Evangelin; Utari; Suharyana; Purnama, Budi; Wijayanta, Agung Tri

    2016-08-01

    The effects of the synthesis temperature on the crystalline structure and the magnetic properties of cobalt ferrite (CoFe2O4) nanoparticles prepared via coprecipitation are discussed. The synthesis was conducted at temperatures of 75 °C, 85 °C and 95 °C. Fourier transform infrared spectroscopy characterization related to a stretching vibration at a wavenumber of 590 cm-1 indicated the formation of a CoFe2O4 metal oxide. In addition, powder X ray diffraction (XRD) characterization proved that the metal oxide was CoFe2O4. Crystallite sizes calculated using the Scherer formula at the strongest peak of the XRD spectra of the samples synthesized at 75 °C, 85 °C and 95 °C were 32 nm, 43 nm and 50.4 nm, respectively. Finally, the results of the vibrating sample magnetometer characterization showed that the saturation magnetization decreased with increasing synthesis temperature, which is related to the dominant preference of Co2+ over Fe3+ cations at the octahedral sites.

  5. Synthesis, Characterization, and Optimization of Co2SnO4 Nanoparticles via Co-precipitation Method

    NASA Astrophysics Data System (ADS)

    Shamirian, Armen; Edrisi, Mohammad; Naderi, Mahnaz

    2013-01-01

    Nano-structured pure Co2SnO4 powders have been synthesized using the co-precipitation method in the presence of oleic acid (OA) as a capping agent. The Taguchi L4 statistical design was used to investigate the effect of the main parameters (i.e., OA concentration, calcination time, and calcination temperature) on Co2SnO4 formation, crystallite size, and morphology. Co2SnO4 particles were characterized by powder x-ray diffraction (XRD), energy-dispersive x-ray spectroscopy, scanning electron microscopy (SEM), Fourier transform of infrared spectroscopy (FT-IR), dynamic light scattering (DLS), and Brunauer-Emmett-Teller (BET) surface area measurements. The formation of small and well-crystalline particles, on the order of 41.12-90.60 nm in crystal size, has been determined from XRD patterns and confirmed by SEM and DLS. The specific surface area was measured by a BET method to be 25.43 m2/g. The particle size of the product was observed by DLS to be in the range of 40-105 nm. The results indicated that calcination temperature has the most significant effect on the produced cobalt stannate crystal size.

  6. A co-precipitation preparation, crystal structure and photoluminescent properties of Er5%:Gd2O3 nanorods

    NASA Astrophysics Data System (ADS)

    Boopathi, G.; Raj, S. Gokul; Kumar, G. Ramesh; Mohan, R.

    2015-06-01

    An inexpensive preparation method is being reported for obtaining erbium doped gadolinium oxide (Er5%:Gd2O3) nanoscale rods. The elongated nanoscale systems, as-formed through a co-precipitation process, are characterized by using X-ray powder diffraction (XRD) patterns, scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) mapping, Ultra Violet-visible (UV-vis.) absorption spectroscopy and photoluminescence (PL) spectroscopy. In addition, the Williamson-Hall (W-H) plot is also performed to distinguish the effect of crystalline size-induced broadening and strain-induced broadening at full-width at half-maximum (FWHM) of the XRD profile. The XRD patterns of as-formed and calcined products show that the phase confirmation. As revealed from the SEM micrographs, the morphology of the products show that the rod-like nanoparticles. The EDX micrographs show that the presence of elements in our samples. The band gap values in calcined samples are found to be in the range of 3.569 eV. Upon 230 nm excitation on calcined samples, three broad emission peaks are observed from PL studies. The possible mechanism for the formation of Er5%:Gd2O3 nanorods is briefly discussed.

  7. Zirconium(IV) tungstate nanoparticles prepared through chemical co-precipitation method and its function as solid acid catalyst

    NASA Astrophysics Data System (ADS)

    Sadanandan, Manoj; Bhaskaran, Beena

    2014-08-01

    In this paper, we report the synthesis of zirconium(IV) tungstate nanoparticles, a new and efficient catalyst for the oxidation of benzyl alcohol and esterification of acetic acid with various alcohols. The nanoparticle catalyst was prepared using the room temperature chemical co-precipitation method. The catalyst was characterized with thermogravimetric and differential thermal analysis, elemental analysis, X-ray diffraction analysis (XRD), fourier transform infrared spectroscopy (FT-IR), high-resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM) and the Brunauer-Emmett-Teller (BET) surface area. The crystallite size was found to be ~20 nm as revealed by XRD, HRTEM and AFM. The Na+ exchange capacity was found to be 2.76 meq g-1 and the surface area of the compound measured using BET method was found to be 250-265 m2 g-1. The high value of ion exchange capacity indicates the presence of surface hydroxyl groups. The prepared nanoparticles have proven to be excellent catalysts for both oxidation and ester synthesis under mild reaction conditions. The mechanism of the catalytic reaction was studied as well.

  8. Structural analysis of Sm{sup 3+} doped nanocrystalline Mg-Cd ferrites prepared by oxalate co-precipitation method

    SciTech Connect

    Gadkari, A.B.; Shinde, T.J.; Vasambekar, P.N.

    2009-11-15

    The structural properties of polycrystalline Sm{sup 3+} doped Mg{sub 1} {sub -} {sub x}Cd{sub x} Fe{sub 2}O{sub 4} (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) have been investigated by oxalate co-precipitation method from high purity sulphates. The samples were sintered at 1050 deg. C for a duration of 5 h. The X-ray diffraction measurements confirmed the formation of a cubic spinel structure. The different parameters like lattice constant, X-ray density, physical density, porosity, crystallite size, site radii and bond length on tetrahedral and octahedral sites have been calculated. The lattice constant increases with an increase in Cd{sup 2+} content and shows non linear behavior. The crystallite size was calculated using Scherrer formula and varies from 28.69 to 32.05 nm. Physical densities were obtained by Archimedes principle. The surface morphology studied by scanning electron microscope shows that the grain size of the samples increases with an increase in Cd{sup 2+} content. The IR spectra show two strong absorption bands around 5.87 x 10{sup 4} m{sup -1} and 4.27 x 10{sup 4} m{sup -1} on the tetrahedral and octahedral sites respectively. IR spectra also show that Sm{sup 3+} occupies the octahedral B-site.

  9. Influencing factors in the CO-precipitation process of superparamagnetic iron oxide nano particles: A model based study

    NASA Astrophysics Data System (ADS)

    Roth, Hans-Christian; Schwaminger, Sebastian P.; Schindler, Michael; Wagner, Friedrich E.; Berensmeier, Sonja

    2015-03-01

    The study, presented here, focuses on the impact of synthesis parameters on the co-precipitation process of superparamagnetic iron oxide nanoparticles. Particle diameters between 3 and 17 nm and saturation magnetizations from 26 to 89 Am2 kg-1 were achieved by variation of iron salt concentration, reaction temperature, ratio of hydroxide ions to iron ions and ratio of Fe3+/Fe2+. All synthesis assays were conceived according to the "design of experiments" method. The results were fitted to significant models. Subsequent validation experiments could confirm the models with an accuracy>95%. The characterization of the chemical composition, as well as structural and magnetic properties was carried out using powder X-ray diffraction, transmission electron microscopy, Raman and Mössbauer spectroscopy and superconducting quantum interference device magnetometry. The results reveal that the particles' saturation magnetization can be enhanced by the employment of high iron salt concentrations and a molar ratio of Fe3+/Fe2+ below 2:1. Furthermore, the particle size can be increased by higher iron salt concentrations and a hyperstoichiometric normal ratio of hydroxide ions to iron ions of 1.4:1. Overall results indicate that the saturation magnetization is directly related to the particle size.

  10. Synthesis of nano-sized ZnO particles by co-precipitation method with variation of heating time

    NASA Astrophysics Data System (ADS)

    Purwaningsih, S. Y.; Pratapa, S.; Triwikantoro, Darminto

    2016-02-01

    Zinc oxide powders have been synthesized by a co-precipitation method at low temperature (85 °C), using zinc acetate dihydrate, ammonia, hydrochloric acid solutions as the reactants. A number of process parameters such as reaction temperature, solution basicity or pH and heating time are the main factors affecting the morphology and physical properties of the ZnO nanostructures. In this work the effect of heating time on the morphology and particles size were studied. The as-synthesized ZnO powders were characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. The samples were also analyzed using Fourier transform infrared (FTIR). Rietveld refinement of XRD data confirms that ZnO crystallizes in the hexagonal wurtzite structure with high degree of purity and the (101) plane predominant. The XRD results show that the average crystallite sizes were about 66, 27 and 12 nm for 3, 4 and 5 h of heating times, respectively. The XRD analysis indicated that a fraction of nano-sized ZnO powders were in the form of aggregates, which was also verified by TEM image. The TEM photograph demonstrated that the nano-sized ZnO particles were a pseudo-spherical shape.

  11. Structural and magnetic characterization of co-precipitated NixZn1-xFe2O4 ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Srinivas, Ch.; Tirupanyam, B. V.; Meena, S. S.; Yusuf, S. M.; Babu, Ch. Seshu; Ramakrishna, K. S.; Potukuchi, D. M.; Sastry, D. L.

    2016-06-01

    A series of NixZn1-xFe2O4 (x=0.5, 0.6 and 0.7) ferrite nanoparticles have been synthesized using a co-precipitation technique, in order to understand the doping effect of nickel on their structural and magnetic properties. XRD and FTIR studies reveal the formation of spinel phase of ferrite samples. Substitution of nickel has promoted the growth of crystallite size (D), resulting the decrease of lattice strain (η). It was also observed that the lattice parameter (a) increases with the increase of Ni2+ ion concentration. All particles exhibit superparamagnetism at room temperature. The hyperfine interaction increases with the increase of nickel substitution, which can be assumed to the decrease of core-shell interactions present in the nanoparticles. The Mössbauer studies witness the existence of Fe3+ ions and absence of Fe2+ ions in the present systems. These superparamagnetic nanoparticles are supposed to be potential candidates for biomedical applications. The results are interpreted in terms of microstructure, cation redistribution and possible core-shell interactions.

  12. Evaluation of solid state properties of solid dispersions prepared by hot-melt extrusion and solvent co-precipitation.

    PubMed

    Dong, Zedong; Chatterji, Ashish; Sandhu, Harpreet; Choi, Duk Soon; Chokshi, Hitesh; Shah, Navnit

    2008-05-01

    The solid state properties of solid dispersions of Compound A in hypromellose acetate succinate (HPMC-AS) prepared by hot-melt extrusion (HME) and solvent co-precipitation (CP) processes were evaluated using powder X-ray diffractometry (PXRD), thermal analysis, optical microscopy, scanning electron microscopy (SEM), FT-IR and Raman spectroscopy, water vapor sorption analyzer, and surface area by BET. PXRD indicated that both processes converted the crystalline drug into amorphous solid dispersions with a glass transition temperature around 104-107 degrees C and both products have similar spectroscopic and hygroscopic properties. The two products have similar true densities; however, the CP product is more porous and has a larger specific surface area than the HME product, as indicated by the BET results and SEM micrographs. Dissolution study using USP apparatus 2 showed that the CP product had a faster dissolution profile, but slower intrinsic dissolution rate than the HME product. The two products have acceptable physical stability after storage in 40 degrees C/75% RH chamber for 3 months. However, the HME product is more stable than the CP product in aqueous suspension formulation.

  13. Magnetic properties of Cr doped Fe3O4 porous nanoparticles prepared through a co-precipitation method using surfactant

    NASA Astrophysics Data System (ADS)

    Duy Nguyen, Hoang; Dzung Nguyen, Trung; Hai Nguyen, Dai; Nguyen, Phuong Tung

    2014-09-01

    Magnetic Cr3+xFe3+2 - xFe2+O4 (0 ≦̸ x ≦̸ 0.1) porous nanoparticles were prepared by the aqueous co-precipitation method. The resulting magnetic nanoparticles were characterized by using an x-ray diffraction (XRD), field enhanced scanning electron microscope (FESEM), transmission electron microscope (TEM), and vibrating sampling magnetometer (VSM). The nitrogen gas adsorption/desorption isotherm showed a microporous structure of the obtained magnetic materials. A rod and round shape of Fe3O4 was observed as using polyvinylpyrrolidone (PVP) and cetyltrimethylammonium bromide (CTAB) surfactant, respectively. The Fe3O4 nanoparticles exhibited superparamagnetic properties with easy separation and re-dispersion in solution by using an external magnet. More remarkably, the saturation magnetization (Ms) was enhanced up to 1.2 times for doping Cr3+ into the Fe3O4 lattice. The effect of surfactants and Cr3+ doping concentrations on size and the magnetic properties of Fe3O4 nanoparticles are studied.

  14. Magnetic and structural properties of nano sized Dy-doped cobalt ferrite synthesized by co-precipitation

    NASA Astrophysics Data System (ADS)

    Karimi, Z.; Mohammadifar, Y.; Shokrollahi, H.; Asl, Sh. Khameneh; Yousefi, Gh.; Karimi, L.

    2014-06-01

    Regarding the various applications of cobalt ferrite as a magnetic ceramic in various scientific and industrial categories, it is essential to modify and optimize its microstructural and magnetic features. Chemical composition (doped elements and their quantities) is a determining factor which has been studied in this research. For this purpose, cobalt-dysprosium ferrite ceramic nanoparticles with the chemical formula Co1-xDyxFe2O4 (x=0, 0.01, 0.03, 0.05, 0.1) were synthesized by the co-precipitation chemical method and then analyzed from the structural and magnetic perspectives. The desirable spinel phase formation was confirmed via x-ray diffractometry, and the other crystallographic parameters and cation distribution were calculated. The microscopic image of the samples showed 15 nm particles. The type and strength of the interionic bonds were determined by infrared spectroscopy. The hysteresis loop of the material was affected noticeably by doped elements as the room temperature saturation magnetization was decreased, but the residual magnetization and coercivity of ferrite were promoted by 50 and 150% after adding dysprosium, respectively. The maximum anisotropy constant, which is equal to 19.1 erg/g for undoped cobalt ferrite, was increased to 45.2 erg/g by doping 0.05 dysprosium. It is worth mentioning that introducing dopants into the lattice led to a great decrease in Curie temperature.

  15. Silicon ball grid array chip carrier

    DOEpatents

    Palmer, David W.; Gassman, Richard A.; Chu, Dahwey

    2000-01-01

    A ball-grid-array integrated circuit (IC) chip carrier formed from a silicon substrate is disclosed. The silicon ball-grid-array chip carrier is of particular use with ICs having peripheral bond pads which can be reconfigured to a ball-grid-array. The use of a semiconductor substrate such as silicon for forming the ball-grid-array chip carrier allows the chip carrier to be fabricated on an IC process line with, at least in part, standard IC processes. Additionally, the silicon chip carrier can include components such as transistors, resistors, capacitors, inductors and sensors to form a "smart" chip carrier which can provide added functionality and testability to one or more ICs mounted on the chip carrier. Types of functionality that can be provided on the "smart" chip carrier include boundary-scan cells, built-in test structures, signal conditioning circuitry, power conditioning circuitry, and a reconfiguration capability. The "smart" chip carrier can also be used to form specialized or application-specific ICs (ASICs) from conventional ICs. Types of sensors that can be included on the silicon ball-grid-array chip carrier include temperature sensors, pressure sensors, stress sensors, inertia or acceleration sensors, and/or chemical sensors. These sensors can be fabricated by IC processes and can include microelectromechanical (MEM) devices.

  16. Preparation of Bi-Pb-Sr-Ca-Cu-O oxide superconductors by coprecipitation of nanosize oxalate precursor powders in the aqueous core of water-in-oil microemulsions

    NASA Astrophysics Data System (ADS)

    Kumar, P.; Pillai, V.; Shah, D. O.

    1993-02-01

    We describe a new technique for the synthesis of ultrahomogeneous nanoparticles of precursor oxalate powder by coprecipitation in the aqueous core of a water-in-oil microemulsion for the preparation of Bi-Pb-Sr-Ca-Cu-O (2223) oxide superconductor. This process ensures a uniform mixing of metal cations down to a scale of at least 10 nm. This finely dispersed precursor powder results in phase pure (2223) oxide superconductor after proper heat treatment.

  17. Recent Advances in Subunit Vaccine Carriers

    PubMed Central

    Vartak, Abhishek; Sucheck, Steven J.

    2016-01-01

    The lower immunogenicity of synthetic subunit antigens, compared to live attenuated vaccines, is being addressed with improved vaccine carriers. Recent reports indicate that the physio-chemical properties of these carriers can be altered to achieve optimal antigen presentation, endosomal escape, particle bio-distribution, and cellular trafficking. The carriers can be modified with various antigens and ligands for dendritic cells targeting. They can also be modified with adjuvants, either covalently or entrapped in the matrix, to improve cellular and humoral immune responses against the antigen. As a result, these multi-functional carrier systems are being explored for use in active immunotherapy against cancer and infectious diseases. Advancing technology, improved analytical methods, and use of computational methodology have also contributed to the development of subunit vaccine carriers. This review details recent breakthroughs in the design of nano-particulate vaccine carriers, including liposomes, polymeric nanoparticles, and inorganic nanoparticles. PMID:27104575

  18. Carriers of the astronomical 2175 ? extinction feature

    SciTech Connect

    Bradley, J; Dai, Z; Ernie, R; Browning, N; Graham, G; Weber, P; Smith, J; Hutcheon, I; Ishii, H; Bajt, S; Floss, C; Stadermann, F

    2004-07-20

    The 2175 {angstrom} extinction feature is by far the strongest spectral signature of interstellar dust observed by astronomers. Forty years after its discovery the origin of the feature and the nature of the carrier remain controversial. The feature is enigmatic because although its central wavelength is almost invariant its bandwidth varies strongly from one sightline to another, suggesting multiple carriers or a single carrier with variable properties. Using a monochromated transmission electron microscope and valence electron energy-loss spectroscopy we have detected a 5.7 eV (2175 {angstrom}) feature in submicrometer-sized interstellar grains within interplanetary dust particles (IDPs) collected in the stratosphere. The carriers are organic carbon and amorphous silicates that are abundant and closely associated with one another both in IDPs and in the interstellar medium. Multiple carriers rather than a single carrier may explain the invariant central wavelength and variable bandwidth of the astronomical 2175 {angstrom} feature.

  19. Ultrafast carriers dynamics in filled-skutterudites

    NASA Astrophysics Data System (ADS)

    Guo, Liang; Xu, Xianfan; Salvador, James R.

    2015-06-01

    Carrier dynamics of filled-skutterudites, an important class of thermoelectric materials, is investigated using ultrafast optical spectroscopy. By tuning the wavelength of the probe laser, charge transfers at different electronic energy levels are interrogated. Analysis based on the Kramers-Kronig relation explains the complex spectroscopy data, which is mainly due to band filling caused by photo-excited carriers and free carrier absorption. The relaxation time of hot carriers is found to be about 0.4-0.6 ps, depending on the electronic energy level, and the characteristic time for carrier-phonon equilibrium is about 0.95 ps. These studies of carrier dynamics, which fundamentally determines the transport properties of thermoelectric material, can provide guidance for the design of materials.

  20. Recent Advances in Subunit Vaccine Carriers.

    PubMed

    Vartak, Abhishek; Sucheck, Steven J

    2016-01-01

    The lower immunogenicity of synthetic subunit antigens, compared to live attenuated vaccines, is being addressed with improved vaccine carriers. Recent reports indicate that the physio-chemical properties of these carriers can be altered to achieve optimal antigen presentation, endosomal escape, particle bio-distribution, and cellular trafficking. The carriers can be modified with various antigens and ligands for dendritic cells targeting. They can also be modified with adjuvants, either covalently or entrapped in the matrix, to improve cellular and humoral immune responses against the antigen. As a result, these multi-functional carrier systems are being explored for use in active immunotherapy against cancer and infectious diseases. Advancing technology, improved analytical methods, and use of computational methodology have also contributed to the development of subunit vaccine carriers. This review details recent breakthroughs in the design of nano-particulate vaccine carriers, including liposomes, polymeric nanoparticles, and inorganic nanoparticles. PMID:27104575

  1. Ultrafast carriers dynamics in filled-skutterudites

    SciTech Connect

    Guo, Liang; Xu, Xianfan; Salvador, James R.

    2015-06-08

    Carrier dynamics of filled-skutterudites, an important class of thermoelectric materials, is investigated using ultrafast optical spectroscopy. By tuning the wavelength of the probe laser, charge transfers at different electronic energy levels are interrogated. Analysis based on the Kramers-Kronig relation explains the complex spectroscopy data, which is mainly due to band filling caused by photo-excited carriers and free carrier absorption. The relaxation time of hot carriers is found to be about 0.4–0.6 ps, depending on the electronic energy level, and the characteristic time for carrier-phonon equilibrium is about 0.95 ps. These studies of carrier dynamics, which fundamentally determines the transport properties of thermoelectric material, can provide guidance for the design of materials.

  2. Method for determination of neptunium in large-sized urine samples using manganese dioxide coprecipitation and 242Pu as yield tracer.

    PubMed

    Qiao, Jixin; Hou, Xiaolin; Roos, Per

    2013-02-01

    A novel method for bioassay of large volumes of human urine samples using manganese dioxide coprecipitation for preconcentration was developed for rapid determination of (237)Np. (242)Pu was utilized as a nonisotopic tracer to monitor the chemical yield of (237)Np. A sequential injection extraction chromatographic (SI-EC) system coupled with inductively coupled plasma mass spectrometry (ICPMS) was exploited to facilitate the rapid column separation and quantification. The analytical results demonstrated satisfactory performance of the MnO(2) coprecipitation as indicated by the high chemical yields close to 100% and high separation capacity of processing up to 5 L of human urine samples. The MnO(2) coprecipitation process is simple and straightforward in which a batch (8-12) of samples can be pretreated within 4 h (i.e., <0.5 h/sample). In connection with the automated column separation and ICPMS quantification, which takes less than 1.5 h in total, the overall analytical time was on average less than 2 h for each sample. The high effectiveness and sample throughput make the developed method well suited for urine bioassay of (237)Np in routine monitoring of occupationally internal radiation exposure and rapid analysis of neptunium contamination level for emergency preparedness.

  3. Simultaneous coprecipitation of lead, cobalt, copper, cadmium, iron and nickel in food samples with zirconium(IV) hydroxide prior to their flame atomic absorption spectrometric determination.

    PubMed

    Citak, Demirhan; Tuzen, Mustafa; Soylak, Mustafa

    2009-09-01

    A simple and new coprecipitation procedure is developed for the determination of trace quantities of heavy metals (lead, cobalt, copper, cadmium, iron and nickel) in natural water and food samples. Analyte ions were coprecipitated by using zirconium(IV) hydroxide. The determination of metal levels was performed by flame atomic absorption spectrometry (FAAS). The influences of analytical parameters including pH, amount of zirconium(IV), sample volume, etc. were investigated on the recoveries of analyte ions. The effects of possible matrix ions were also examined. The recoveries of the analyte ions were in the range of 95-100%. Preconcentration factor was calculated as 25. The detection limits for the analyte ions based on 3 sigma (n=21) were in the range of 0.27-2.50 microgL(-1). Relative standard deviation was found to be lower than 8%. The validation of the presented coprecipitation procedure was performed by the analysis certified reference materials (GBW 07605 Tea and LGC 6010 Hard drinking water). The procedure was successfully applied to natural waters and food samples like coffee, fish, tobacco, black and green tea. PMID:19539005

  4. 49 CFR 369.1 - Annual reports of motor carriers of property, motor carriers of household goods, and dual...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Regulations Relating to Transportation (Continued) FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION, DEPARTMENT OF... dual property motor carriers, must file Motor Carrier Annual Report Form M (Form M). Carriers must file... property and class I household goods motor carriers must file Motor Carrier Quarterly Report Form QFR...

  5. Laboratory Studies of DIB Carriers

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.

    1995-01-01

    Spectroscopic studies of the following potential diffuse interstellar band (DIB) carriers are reviewed: unspecified organics, carbon chains, polycyclic aromatic hydrocarbons (PAHs), fullerenes and derivatives, as well as porphyrins and related material. An assessment of each is given, along with suggestions for further experimental studies needed to fully test each candidate. Of the experimental techniques in common use matrix isolation spectroscopy with neon matrices is the most appropriate for the DIBs. The low vapor pressure and high reactivity of these materials preclude gas phase studies on many of these species. At this point, given the type and quality of published data available, carbon chains and PARs are the most promising candidates for a number of the DIBs.

  6. Carriers by chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Mronga, Norbert; Adel, J.; Czech, Erwin

    1990-07-01

    Printed materials are affecting people's lives in a variety of ways and to a constantly increasing extent, both in the private and in the business spheres. In particular, the predicted reduction of printed materials resulting from electronic data processing - the so-called "paperless electronic office" - has not occured, indeed quite the reverse. In recent years electrophotographic reprography has established itself successfully as a competitor to conventional printing processes. In the office a photocopier is now a part of the standard equipment. Because of BASF's traditional intensive involvement with pigments and colored printing inks its interest in new technologies in these areas is especially great. BASF has therefore been engaged in research on carriers for some years now.

  7. Charge carrier thermalization in organic diodes

    PubMed Central

    van der Kaap, N. J.; Koster, L. J. A.

    2016-01-01

    Charge carrier mobilities of organic semiconductors are often characterized using steady-state measurements of space charge limited diodes. These measurements assume that charge carriers are in a steady-state equilibrium. In reality, however, energetically hot carriers are introduces by photo-excitation and injection into highly energetic sites from the electrodes. These carriers perturb the equilibrium density of occupied states, and therefore change the overall charge transport properties. In this paper, we look into the effect of energetically hot carriers on the charge transport in organic semiconductors using steady state kinetic Monte Carlo simulations. For injected hot carriers in a typical organic semiconductor, rapid energetic relaxation occurs in the order of tens of nanoseconds, which is much faster than the typical transit time of a charge carrier throught the device. Furthermore, we investigate the impact of photo-generated carriers on the steady-state mobility. For a typical organic voltaic material, an increase in mobility of a factor of 1.1 is found. Therefore, we conclude that the impact of energetically hot carriers on normal device operation is limited. PMID:26791095

  8. CARRIER/CASK HANDLING SYSTEM DESCRIPTION DOCUMENT

    SciTech Connect

    E.F. Loros

    2000-06-23

    The Carrier/Cask Handling System receives casks on railcars and legal-weight trucks (LWTs) (transporters) that transport loaded casks and empty overpacks to the Monitored Geologic Repository (MGR) from the Carrier/Cask Transport System. Casks that come to the MGR on heavy-haul trucks (HHTs) are transferred onto railcars before being brought into the Carrier/Cask Handling System. The system is the interfacing system between the railcars and LWTs and the Assembly Transfer System (ATS) and Canister Transfer System (CTS). The Carrier/Cask Handling System removes loaded casks from the cask transporters and transfers the casks to a transfer cart for either the ATS or CTS, as appropriate, based on cask contents. The Carrier/Cask Handling System receives the returned empty casks from the ATS and CTS and mounts the casks back onto the transporters for reshipment. If necessary, the Carrier/Cask Handling System can also mount loaded casks back onto the transporters and remove empty casks from the transporters. The Carrier/Cask Handling System receives overpacks from the ATS loaded with canisters that have been cut open and emptied and mounts the overpacks back onto the transporters for disposal. If necessary, the Carrier/Cask Handling System can also mount empty overpacks back onto the transporters and remove loaded overpacks from them. The Carrier/Cask Handling System is located within the Carrier Bay of the Waste Handling Building System. The system consists of cranes, hoists, manipulators, and supporting equipment. The Carrier/Cask Handling System is designed with the tooling and fixtures necessary for handling a variety of casks. The Carrier/Cask Handling System performance and reliability are sufficient to support the shipping and emplacement schedules for the MGR. The Carrier/Cask Handling System interfaces with the Carrier/Cask Transport System, ATS, and CTS as noted above. The Carrier/Cask Handling System interfaces with the Waste Handling Building System for building

  9. Redox properties of nanostructured lanthanide-doped ceria spheres prepared by microwave assisted hydrothermal homogeneous co-precipitation.

    PubMed

    Muñoz, F F; Acuña, L M; Albornoz, C A; Leyva, A G; Baker, R T; Fuentes, R O

    2015-01-01

    In this work, nanostructured LnxCe(1-x)O2-δ (Ln: Gd and Pr; x = 0.1 and 0.2) spheres were synthesized by microwave assisted hydrothermal homogeneous co-precipitation and their properties were characterized by synchrotron radiation XRD, X-ray absorption near-edge spectroscopy (XANES) and scanning and high-resolution electron microscopy (SEM and HRTEM). In situ XRD and XANES experiments were carried out under reducing and oxidizing conditions in order to investigate the redox behaviour of these materials. The nanostructured mixed oxide spheres were found to have a cubic crystal structure (Fm3m space group). The spheres were composed of nanoparticles with an average crystallite size of about 10 nm. The Ln(0.1)Ce(0.9)O2-δ compositions exhibited the highest specific surface area (∼ 60 m(2) g(-1)). In situ XRD experiments showed an increase in lattice parameters upon reduction, which was attributed to the reduction of Ce(4+) and Pr(4+) cations to Ce(3+) and Pr(3+), which have larger radii, and to the associated increase in VO concentration. This increase in lattice parameters was considerably more pronounced for PrDC than GDC, and was explained by the considerably larger change in ionic radius for Pr upon reduction. XANES absorption experiments at the Ce and Pr L3-edge showed that the changes observed upon reduction of the Pr-containing samples resulted mostly from the formation of Pr(3+) rather than Ce(3+), and supported the previously reported proposal that Pr(3+) has a stabilizing effect on Ce(4+).

  10. Adsorption and co-precipitation behavior of arsenate, chromate, selenate and boric acid with synthetic allophane-like materials.

    PubMed

    Opiso, Einstine; Sato, Tsutomu; Yoneda, Tetsuro

    2009-10-15

    Pollution caused by boric acid and toxic anions such as As(V), Cr(VI) and Se(VI) is hazardous to human health and environment. The sorption characteristics of these environmentally significant ionic species on allophane-like nanoparticles were investigated in order to determine whether allophane can reduce their mobility in the subsurface environment at circum-neutral pH condition. Solutions containing 100 or 150 mmol of AlCl(3)x6H(2)O were mixed to 100 mmol of Na(4)SiO(4) and the pH were adjusted to 6.4+/-0.3. The mineral suspensions were shaken for 1h and incubated at 80 degrees C for 5 days. Appropriate amounts of As, B, Cr and Se solutions were added separately during and after allophane precipitation. The results showed that As(V) and boric acid can be irreversibly fixed during co-precipitation in addition to surface adsorption. However, Cr(VI) and Se(VI) retention during and after allophane precipitation is mainly controlled by surface adsorption. The structurally fixed As(V) and boric acid were more resistant to release than those bound on the surface. The sorption characteristics of oxyanions and boric acid were also influenced by the final Si/Al molar ratio of allophane in which Al-rich allophane tend to have higher uptake capacity. The overall results of this study have demonstrated the role of allophane-like nanoparticles and the effect of its Si/Al ratio on As, B, Cr and Se transport processes in the subsurface environment.

  11. Moessbauer and magnetic study of Mn, Zr and Cd substituted W-type hexaferrites prepared by co-precipitation

    SciTech Connect

    Iqbal, Muhammad Javed; Khan, Rafaqat Ali; Mizukami, Shigemi; Miyazaki, Terunobu

    2011-11-15

    Highlights: {yields} Zr and Cd ions substitute tetrahedral 4e and 4f{sub IV} sites while Mn ions occupy octahedral 6g and 4f sites. {yields} Doping of W-type hexaferrites with Mn, Zr and Cd improves the values of M{sub s} and M{sub r}. {yields} The enhancement of magnetic characteristic togetherwith the formation of rice shaped W-type hexaferrites nanoparticles is promising for imaging and sensing devices. {yields} The synthesized materials are suitable for magnetic data storage with high density. -- Abstract: BaCo{sub 2-x}Mn{sub x}Fe{sub 16-2y}(Zr-Cd){sub y}O{sub 27} (x = 0-0.5 and y = 0-1.0) hexaferrite nanocrystallites of average sizes in the range of 33-42 nm are synthesized by the chemical co-precipitation method. The synthesized materials are characterized using different techniques including X-ray diffraction (XRD), energy dispersive X-ray florescence (ED-XRF), scanning electron microscope (SEM), Moessbauer spectrometer and vibrating-sample magnetometer (VSM). Based on analysis of the data obtained from Moessbauer spectral studies, doping is believed to have occurred preferably in the vicinity of 12k sub-lattice, i.e. f{sub IV} (4e, 4f{sub IV}), 2b (6g, 4f) and 2d site. Variations in the saturation magnetization (77.1-60.9 emu g{sup -1}), remanent magnetization (22.08-31.23 emu g{sup -1}) and coercivity (1570.1-674.7 Oe) exhibit tunable behavior with dopant content and therefore can be useful for application in various magnetic devices.

  12. Role of Fe(II), phosphate, silicate, sulfate, and carbonate in arsenic uptake by coprecipitation in synthetic and natural groundwater.

    PubMed

    Ciardelli, Mark C; Xu, Huifang; Sahai, Nita

    2008-02-01

    Competitive effects of phosphate, silicate, sulfate, and carbonate on As(III) and As(V) removal at pH approximately 7.2 have been investigated to test the feasibility of Fe(II)(aq) and hydroxylapatite crystals as inexpensive and potentially efficient agents for remediation of contaminated well-water, using Bangladesh as a type study. Arsenic(III) removal approximately 50-55% is achieved, when Fe(II)(aq) oxidizes to Fe(III) and precipitates as Fe(OH)3 at 25 degrees C and 3h reaction time, in the presence of all the oxyanion. Similar results were obtained for well-water samples from two sites in Bangladesh. Heating at 95 degrees C for 24h results in 70% As(III) uptake due to precipitation of magnesian calcite. A two-step process, Fe(II) oxidation and Fe(OH)3 precipitation at 25 degrees C for 2h, followed by magnesian calcite precipitation at 95 degrees C for 3h, yields approximately 65% arsenic removal while reducing the expensive heating period. In the absence of silicate, up to 70% As(III) uptake occurs at 25 degrees C. In all cases, As(III) was oxidized to As(V) in solution by dissolved oxygen and the reaction rate was probably promoted by intermediates formed during Fe(II) oxidation. Iron-catalyzed oxidation of As(III) by oxygen and hydrogen peroxide is pH-dependent with formation of oxidants in the Fenton reaction. Buffering pH at near-neutral values by dissolved carbonate and hydroxylapatite seeds is important for faster Fe(II) oxidation kinetics ensuring rapid coprecipitation of As as As(V) in the ferric phases.

  13. Carrier Screening: Past, Present, and Future

    PubMed Central

    Bajaj, Komal; Gross, Susan J.

    2014-01-01

    To date, preconceptual and prenatal patients have been offered gene-by-gene, disorder-by-disorder carrier screening. Newer techniques allow screening of many disorders at one time. The goal of this review is to provide an overview of the current practice and future direction of carrier screening within the preconceptual/prenatal setting.

  14. 49 CFR 1139.21 - Study carriers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Industry § 1139.21 Study carriers. (a) For the purposes of this proceeding the “study carriers” shall... charges, derived $500,000 or more in annual operating revenues from the issue traffic, or 1 percent or more of the total annual operating revenues received by all Class I carriers from the issue...

  15. 49 CFR 1139.21 - Study carriers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 8 2011-10-01 2011-10-01 false Study carriers. 1139.21 Section 1139.21 Transportation Other Regulations Relating to Transportation (Continued) SURFACE TRANSPORTATION BOARD, DEPARTMENT OF TRANSPORTATION RULES OF PRACTICE PROCEDURES IN MOTOR CARRIER REVENUE PROCEEDINGS Intercity...

  16. Hydrogen: the future energy carrier.

    PubMed

    Züttel, Andreas; Remhof, Arndt; Borgschulte, Andreas; Friedrichs, Oliver

    2010-07-28

    Since the beginning of the twenty-first century the limitations of the fossil age with regard to the continuing growth of energy demand, the peaking mining rate of oil, the growing impact of CO2 emissions on the environment and the dependency of the economy in the industrialized world on the availability of fossil fuels became very obvious. A major change in the energy economy from fossil energy carriers to renewable energy fluxes is necessary. The main challenge is to efficiently convert renewable energy into electricity and the storage of electricity or the production of a synthetic fuel. Hydrogen is produced from water by electricity through an electrolyser. The storage of hydrogen in its molecular or atomic form is a materials challenge. Some hydrides are known to exhibit a hydrogen density comparable to oil; however, these hydrides require a sophisticated storage system. The system energy density is significantly smaller than the energy density of fossil fuels. An interesting alternative to the direct storage of hydrogen are synthetic hydrocarbons produced from hydrogen and CO2 extracted from the atmosphere. They are CO2 neutral and stored like fossil fuels. Conventional combustion engines and turbines can be used in order to convert the stored energy into work and heat.

  17. Optoelectronic characterization of carrier extraction in a hot carrier photovoltaic cell structure

    NASA Astrophysics Data System (ADS)

    Dimmock, James A. R.; Kauer, Matthias; Smith, Katherine; Liu, Huiyun; Stavrinou, Paul N.; Ekins-Daukes, Nicholas J.

    2016-07-01

    A hot carrier photovoltaic cell requires extraction of electrons on a timescale faster than they can lose energy to the lattice. We optically and optoelectronically characterize two resonant tunneling structures, showing their compatability with hot carrier photovoltaic operation, demonstrating structural and carrier extraction properties necessary for such a device. In particular we use time resolved and temperature dependent photoluminescence to determine extraction timescales and energy levels in the structures and demonstrate fast carrier extraction by tunneling. We also show that such devices are capable of extracting photo-generated electrons at high carrier densities, with an open circuit voltage in excess of 1 V.

  18. 77 FR 46555 - Motor Carrier Safety Advisory Committee: Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-03

    ... Federal Motor Carrier Safety Administration Motor Carrier Safety Advisory Committee: Public Meeting AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT. ACTION: Notice of meeting of Motor Carrier... major motor carrier safety provisions of the recently enacted Moving Ahead for Progress in the...

  19. Synthesis and characterization of sulfate and dodecylbenzenesulfonate intercalated zinc-iron layered double hydroxides by one-step coprecipitation route

    SciTech Connect

    Zhang Hui Wen Xing; Wang Yingxia

    2007-05-15

    Inorganic sulfate- and organic dodecylbenzenesulfonate (DBS)-intercalated zinc-iron layered double hydroxides (LDHs) materials were prepared by one-step coprecipitation method from a mixed salt solutions containing Zn(II), Fe(II) and Fe(III) salts. The as-prepared samples have been characterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), low-temperature nitrogen adsorption, scanning electron microscopy (SEM), inductively coupled plasma emission spectroscopy (ICP), and Moessbauer spectroscopy (MS). The XRD analyses demonstrate the typical LDH-like layered structural characteristics of both products. The room temperature MS results reveal the characteristics of both the Fe(II) and Fe(III) species for SO{sub 4} {sup 2-}-containing product, while only the Fe(III) characteristic for DBS-containing one. The combination characterization results and Rietveld analysis illustrate that the SO{sub 4} {sup 2-}-containing product possesses the Green Rust two (GR2)-like crystal structure with an approximate chemical composition of [Zn{sub 0.435}.Fe{sup II} {sub 0.094}.Fe{sup III} {sub 0.470}.(OH){sub 2}].(SO{sub 4} {sup 2-}){sub 0.235}.1.0H{sub 2}O, while the DBS-containing one exhibits the common LDH compound-like structure. The contact angle measurement indicates the evident hydrophobic properties of DBS-containing nanocomposite, compared with SO{sub 4} {sup 2-}-containing product, due to the modification of the internal and external surface of LDHs by the organic hydrophobic chain of DBS. - Graphical abstract: For Zn{sup 2+}-Fe{sup 2+}-Fe{sup 3+} GR2(SO{sub 4} {sup 2-}), according to the derived chemical formula, Fe{sup 3+} was arranged at 1a (0, 0, 0) position, while all Zn{sup 2+} were in 2d position with the occupancy 0.645, and the left part of 2d positions were taken by Fe{sup 2+}/Fe{sup 3+}.

  20. Calcium regulation of mitochondrial carriers.

    PubMed

    Del Arco, Araceli; Contreras, Laura; Pardo, Beatriz; Satrustegui, Jorgina

    2016-10-01

    Mitochondrial function is regulated by calcium. In addition to the long known effects of matrix Ca(2+), regulation of metabolite transport by extramitochondrial Ca(2+) represents an alternative Ca(2+)-dependent mechanism to regulate mitochondrial function. The Ca(2+) regulated mitochondrial transporters (CaMCs) are well suited for that role, as they contain long N-terminal extensions harboring EF-hand Ca(2+) binding domains facing the intermembrane space. They fall in two groups, the aspartate/glutamate exchangers, AGCs, major components of the NADH malate aspartate shuttle (MAS) and urea cycle, and the ATP-Mg(2+)/Pi exchangers or short CaMCs (APCs or SCaMCs). The AGCs are activated by relatively low Ca(2+) levels only slightly higher than resting Ca(2+), whereas all SCaMCs studied so far require strong Ca(2+) signals, above micromolar, for activation. In addition, AGCs are not strictly Ca(2+) dependent, being active even in Ca(2+)-free conditions. Thus, AGCs are well suited to respond to small Ca(2+) signals and that do not reach mitochondria. In contrast, ATP-Mg(2+)/Pi carriers are inactive in Ca(2+) free conditions and activation requires Ca(2+) signals that will also activate the calcium uniporter (MCU). By changing the net content of adenine nucleotides of the matrix upon activation, SCaMCs regulate the activity of the permeability transition pore, and the Ca(2+) retention capacity of mitochondria (CRC), two functions synergizing with those of the MCU. The different Ca(2+) activation properties of the two CaMCs are discussed in relation to their newly obtained structures. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou. PMID:27033520

  1. Calcium regulation of mitochondrial carriers.

    PubMed

    Del Arco, Araceli; Contreras, Laura; Pardo, Beatriz; Satrustegui, Jorgina

    2016-10-01

    Mitochondrial function is regulated by calcium. In addition to the long known effects of matrix Ca(2+), regulation of metabolite transport by extramitochondrial Ca(2+) represents an alternative Ca(2+)-dependent mechanism to regulate mitochondrial function. The Ca(2+) regulated mitochondrial transporters (CaMCs) are well suited for that role, as they contain long N-terminal extensions harboring EF-hand Ca(2+) binding domains facing the intermembrane space. They fall in two groups, the aspartate/glutamate exchangers, AGCs, major components of the NADH malate aspartate shuttle (MAS) and urea cycle, and the ATP-Mg(2+)/Pi exchangers or short CaMCs (APCs or SCaMCs). The AGCs are activated by relatively low Ca(2+) levels only slightly higher than resting Ca(2+), whereas all SCaMCs studied so far require strong Ca(2+) signals, above micromolar, for activation. In addition, AGCs are not strictly Ca(2+) dependent, being active even in Ca(2+)-free conditions. Thus, AGCs are well suited to respond to small Ca(2+) signals and that do not reach mitochondria. In contrast, ATP-Mg(2+)/Pi carriers are inactive in Ca(2+) free conditions and activation requires Ca(2+) signals that will also activate the calcium uniporter (MCU). By changing the net content of adenine nucleotides of the matrix upon activation, SCaMCs regulate the activity of the permeability transition pore, and the Ca(2+) retention capacity of mitochondria (CRC), two functions synergizing with those of the MCU. The different Ca(2+) activation properties of the two CaMCs are discussed in relation to their newly obtained structures. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou.

  2. Experimental study of germanium adsorption on goethite and germanium coprecipitation with iron hydroxide: X-ray absorption fine structure and macroscopic characterization

    NASA Astrophysics Data System (ADS)

    Pokrovsky, O. S.; Pokrovski, G. S.; Schott, J.; Galy, A.

    2006-07-01

    Adsorption of germanium on goethite was studied at 25 °C in batch reactors as a function of pH (1-12), germanium concentration in solution (10 -7 to 0.002 M) and solid/solution ratio (1.8-17 g/L). The maximal surface site density determined via Ge adsorption experiments at pH from 6 to 10 is equal to 2.5 ± 0.1 μmol/m 2. The percentage of adsorbed Ge increases with pH at pH < 9, reaches a maximum at pH ˜ 9 and slightly decreases when pH is further increased to 11. These results allowed generation of a 2-p K Surface Complexation Model (SCM) which implies a constant capacitance of the electric double layer and postulates the presence of two Ge complexes, >FeO-Ge(OH)30 and >FeO-GeO(OH)2-, at the goethite-solution interface. Coprecipitation of Ge with iron oxy(hydr)oxides formed during Fe(II) oxidation by atmospheric oxygen or by Fe(III) hydrolysis in neutral solutions led to high Ge incorporations in solid with maximal Ge/Fe molar ratio close to 0.5. The molar Ge/Fe ratio in precipitated solid is proportional to that in the initial solution according to the equation (Ge/Fe) solid = k × (Ge/Fe) solution with 0.7 ⩽ k ⩽ 1.0. The structure of adsorbed and coprecipitated Ge complexes was further characterized using XAFS spectroscopy. In agreement with previous data on oxyanions adsorption on goethite, bi-dentate bi-nuclear surface complexes composed of tetrahedrally coordinated Ge attached to the corners of two adjacent Fe octahedra represent the dominant contribution to the EXAFS signal. Coprecipitated samples with Ge/Fe molar ratios >0.1, and samples not aged in solution (<1 day) having intermediate Ge/Fe ratios (0.01-0.1) show 4 ± 0.3 oxygen atoms at 1.76 ± 0.01 Å around Ge. Samples less concentrated in Ge (0.001 < Ge/Fe < 0.10) and aged longer times in solution (up to 280 days) exhibit a splitting of the first atomic shell with Ge in both tetrahedral ( R = 1.77 ± 0.02 Å) and octahedral ( R = 1.92 ± 0.03 Å) coordination with oxygen. In these samples

  3. Synthesis of YAG nanopowder by the co-precipitation method: Influence of pH and study of the reaction mechanisms

    SciTech Connect

    Marlot, Caroline; Barraud, Elodie; Le Gallet, Sophie; Eichhorn, Marc; Bernard, Frederic

    2012-07-15

    YAG nanopowders with an average grain size of 30 nm have been successfully synthesized by the co-precipitation method using nitrates with precipitant of ammonium hydrogen carbonate. The influence of precipitation conditions such as pH, aging time and calcination temperature on the formation of secondary phases has been studied. The accurate control of pH value at every stage of precipitation process is crucial to avoid the presence of YAM (Yttrium Aluminium Monoclinic, Y{sub 4}Al{sub 2}O{sub 9}) and yttrium oxide (Y{sub 2}O{sub 3}) after calcination. The reaction mechanisms have been investigated using different techniques such as infrared spectroscopy, x-ray diffraction and thermal analyses. The YAG phase is formed around 1050 Degree-Sign C passing through an intermediate phase called YAP (Yttrium Aluminium Perovskite, YAlO{sub 3}). Local chemical heterogeneities are responsible for the deviation of the Y:Al ratio and the formation of YAP during heat treatment. - Graphical abstract: Synthesis of YAG nanopowder by the co-precipitation method: Influence of pH and study of the reaction mechanisms, Marlot et al. Highlights: Black-Right-Pointing-Pointer Synthesis of pure YAG nanoparticles by the co-precipitation method. Black-Right-Pointing-Pointer Influence of pH value on the formation of secondary phases all along the process. Black-Right-Pointing-Pointer Study of the importance of pH using titration method. Black-Right-Pointing-Pointer Chemical evolution of the precursor during calcinations. Black-Right-Pointing-Pointer Proposition for reaction mechanisms.

  4. Reduction of ferrihydrite with adsorbed and coprecipitated organic matter: microbial reduction by Geobacter bremensis vs. abiotic reduction by Na-dithionite

    NASA Astrophysics Data System (ADS)

    Eusterhues, K.; Hädrich, A.; Neidhardt, J.; Küsel, K.; Keller, T. F.; Jandt, K. D.; Totsche, K. U.

    2014-04-01

    Ferrihydrite (Fh) is a widespread poorly crystalline Fe oxide which becomes easily coated by natural organic matter (OM) in the environment. This mineral-bound OM entirely changes the mineral surface properties and therefore the reactivity of the original mineral. Here, we investigated the reactivity of 2-line Fh, Fh with adsorbed OM and Fh coprecipitated with OM towards microbial and abiotic reduction of Fe(III). As a surrogate for dissolved soil OM we used a water extract of a Podzol forest floor. Fh-OM associations with different OM-loadings were reduced either by Geobacter bremensis or abiotically by Na-dithionite. Both types of experiments showed decreasing initial Fe reduction rates and decreasing degrees of reduction with increasing amounts of mineral-bound OM. At similar OM-loadings, coprecipitated Fhs were more reactive than Fhs with adsorbed OM. The difference can be explained by the smaller crystal size and poor crystallinity of such coprecipitates. At small OM loadings this led to even faster Fe reduction rates than found for pure Fh. The amount of mineral-bound OM also affected the formation of secondary minerals: goethite was only found after reduction of OM-free Fh and siderite was only detected when Fhs with relatively low amounts of mineral-bound OM were reduced. We conclude that direct contact of G. bremensis to the Fe oxide mineral surface was inhibited when blocked by OM. Consequently, mineral-bound OM shall be taken into account besides Fe(II) accumulation as a further widespread mechanism to slow down reductive dissolution.

  5. Comparison of structural and luminescence properties of Dy{sub 2}O{sub 3} nanopowders synthesized by co-precipitation and green combustion routes

    SciTech Connect

    Chandrasekhar, M.; Nagabhushana, H.; Sudheerkumar, K.H.; Dhananjaya, N.; Sharma, S.C.; Kavyashree, D.; Shivakumara, C.; Nagabhushana, B.M.

    2014-07-01

    Highlights: • Dy{sub 2}O{sub 3} nanopowders were prepared by co-precipitation and eco-friendly green combustion route using plant latex. • Both the products show excellent chromaticity coordinates in the white region, which were quite useful for white LED’s. • Thermoluminescence response of the Dy{sub 2}O{sub 3} product prepared by green synthesis was higher when compared to co-precipitation route. • Structural parameters of Dy{sub 2}O{sub 3} were estimated using Rietveld refinement. • The development of nanosize materials using eco-friendly resources was an attractive non-hazardous chemical route. - Abstract: Dysprosium oxide (Dy{sub 2}O{sub 3}) nanopowders were prepared by co-precipitation (CP) and eco-friendly green combustion (GC) routes. SEM micrographs prepared by CP route show smooth rods with various lengths and diameters while, GC route show porous, agglomerated particles. The results were further confirmed by TEM. Thermoluminescence (TL) responses of the nanopowder prepared by both the routes were studied using γ-rays. A well resolved glow peak at 353 °C along with less intense peak at 183 °C was observed in GC route while, in CP a single glow peak at 364 °C was observed. The kinetic parameters were estimated using Chen’s glow peak route. Photoluminescence (PL) of Dy{sub 2}O{sub 3} shows peaks at 481, 577, 666 and 756 nm which were attributed to Dy{sup 3+} transitions of {sup 4}F{sub 9/2}⟶{sup 6}H{sub 15/2}, {sup 6}H{sub 13/2}, {sup 6}H{sub 11/2} and {sup 6}H{sub 9/2}, respectively. Color co-ordinate values were located in the white region as a result the product may be useful for the fabrication of WLED’S.

  6. Comparative physicochemical properties of hydrocortisone-PVP composites prepared using supercritical carbon dioxide by the GAS anti-solvent recrystallization process, by coprecipitation and by spray drying.

    PubMed

    Corrigan, Owen I; Crean, Abina M

    2002-10-01

    Hydrocortisone-PVP composites were successfully prepared using the supercritical fluid gas anti-solvent method (GAS). Analysis by differential scanning calorimetry DSC and powder X-ray diffraction (XRD) indicated that these systems were more crystalline than corresponding systems prepared by spray drying. These systems, prepared by the GAS method were more similar in physicochemical properties to coprecipitates prepared by conventional solvent evaporation. Compressed composites of hydrocortisone-PVP systems, prepared by the GAS method, had dissolution rates lower than those of corresponding systems prepared by the other processing methods but equivalent to those of corresponding physical mixtures.

  7. Effect of Gallium and Indium Co-Substituting on Upconversion Properties of Er/Yb:Yttrium Aluminum Garnet Powders Prepared by the Co-Precipitation Method.

    PubMed

    Zhang, Wei; Liang, Yun-Ling; Hu, Zheng-Fa; Feng, Zu-Yong; Lun, Ma; Zhang, Xiu-ping; Sheng, Xia; Liu, Qian; Luo, Jie

    2016-04-01

    Gallium and Indium co-substituted Yb, Er:YAG was fabricated through the chemical co-precipitation method. The formation process and structure of the Ga3+ and In3+ substituted phosphor powders were characterized by the X-ray diffraction, thermo-gravimetry analyzer, infrared spectra, and X-ray photoelectron spectroscopy, and the effects of Ga3+ and In3+ concentration on the luminescence properties were investigated by spectrum. The results showed that the blue shift occurred after the substitution of Ga3+ and In3+ for Al3+ in matrix, and the intensity of emission spectrum was affected by the concentration of Ga3+ and In3+. PMID:27451659

  8. Effect of Gallium and Indium Co-Substituting on Upconversion Properties of Er/Yb:Yttrium Aluminum Garnet Powders Prepared by the Co-Precipitation Method.

    PubMed

    Zhang, Wei; Liang, Yun-Ling; Hu, Zheng-Fa; Feng, Zu-Yong; Lun, Ma; Zhang, Xiu-ping; Sheng, Xia; Liu, Qian; Luo, Jie

    2016-04-01

    Gallium and Indium co-substituted Yb, Er:YAG was fabricated through the chemical co-precipitation method. The formation process and structure of the Ga3+ and In3+ substituted phosphor powders were characterized by the X-ray diffraction, thermo-gravimetry analyzer, infrared spectra, and X-ray photoelectron spectroscopy, and the effects of Ga3+ and In3+ concentration on the luminescence properties were investigated by spectrum. The results showed that the blue shift occurred after the substitution of Ga3+ and In3+ for Al3+ in matrix, and the intensity of emission spectrum was affected by the concentration of Ga3+ and In3+.

  9. Stable iron isotope fractionation between aqueous Fe(II) and model Archean ocean Fe-Si coprecipitates and implications for iron isotope variations in the ancient rock record

    NASA Astrophysics Data System (ADS)

    Wu, Lingling; Percak-Dennett, Elizabeth M.; Beard, Brian L.; Roden, Eric E.; Johnson, Clark M.

    2012-05-01

    Iron isotope fractionation between aqueous Fe(II) (Fe(II)aq) and two amorphous Fe(III) oxide-Si coprecipitates was investigated in an aqueous medium that simulated Archean marine conditions, including saturated amorphous silica, low sulfate, and zero dissolved oxygen. The equilibrium isotope fractionation (in 56Fe/54Fe) between Fe(II)aq and Fe(III)-Si coprecipitates at circum-neutral pH, as inferred by the three-isotope method, was -3.51 ± 0.20 (2σ)‰ and -3.99 ± 0.17 (2σ)‰ for coprecipitates that had Fe:Si molar ratios of 1:2 and 1:3, respectively. These results, when combined with earlier work, indicate that the equilibrium isotope fractionation factor between Fe(II)aq and Fe(III)-Si coprecipitates changes as a function of Fe:Si ratio of the solid. Isotopic fractionation was least negative when Fe:Si = 1:1 and most negative when Fe:Si = 1:3. This change corresponds with changes in the local structure of iron, as revealed by prior spectroscopic studies. The kinetics of isotopic exchange was controlled by movement of Fe(II) and Si, where sorption of Fe(II) from aqueous to solid phase facilitated atom exchange, but sorption of Si hindered isotopic exchange through blockage of reactive surface sites. Although Fe(II)-Fe(III) isotopic exchange rates were a function of solid and solution compositions in the current study, in all cases they were much higher than that determined in previous studies of aqueous Fe(III) and ferrihydrite interaction, highlighting the importance of electron exchange in promoting Fe atom exchange. When compared to analogous microbial reduction experiments of overlapping Fe(II) to Fe(III) ratios, isotopic exchange rates were faster in the biological experiments, likely due to promotion of atom exchange by the solid-phase Fe(II) produced in the biological experiments. These results provide constraints for interpreting the relatively large range of Fe isotope compositions in Precambrian marine sedimentary rocks, and highlight important

  10. Formation of superconducting Bi sub 2-y Pb sub y Sr sub 2 Ca sub 2 Cu sub 3 O sub x from coprecipitated oxalates

    SciTech Connect

    Bernhard, K.; Gritzner, G.; Wang, Xianzhong; Baeuerle, D. )

    1990-06-01

    The conditions for the coprecipitation of Bi{sup 3+}, Pb{sup 2+}, Ca{sup 2+} as oxalates are reported. These oxalates were used as precursors for the formation of Bi{sub 2-y}Pb{sub y}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} superconducting ceramics. The behavior of the oxalates upon heat treatment was studied by thermogravimetry. Both the oxalates and the superconducting oxides were analyzed and characterized by atomic absorption spectroscopy and by X-ray diffraction.

  11. Redox properties of nanostructured lanthanide-doped ceria spheres prepared by microwave assisted hydrothermal homogeneous co-precipitation

    NASA Astrophysics Data System (ADS)

    Muñoz, F. F.; Acuña, L. M.; Albornoz, C. A.; Leyva, A. G.; Baker, R. T.; Fuentes, R. O.

    2014-11-01

    In this work, nanostructured LnxCe1-xO2-δ (Ln: Gd and Pr; x = 0.1 and 0.2) spheres were synthesized by microwave assisted hydrothermal homogeneous co-precipitation and their properties were characterized by synchrotron radiation XRD, X-ray absorption near-edge spectroscopy (XANES) and scanning and high-resolution electron microscopy (SEM and HRTEM). In situ XRD and XANES experiments were carried out under reducing and oxidizing conditions in order to investigate the redox behaviour of these materials. The nanostructured mixed oxide spheres were found to have a cubic crystal structure (Fm3m space group). The spheres were composed of nanoparticles with an average crystallite size of about 10 nm. The Ln0.1Ce0.9O2-δ compositions exhibited the highest specific surface area (~60 m2 g-1). In situ XRD experiments showed an increase in lattice parameters upon reduction, which was attributed to the reduction of Ce4+ and Pr4+ cations to Ce3+ and Pr3+, which have larger radii, and to the associated increase in VO concentration. This increase in lattice parameters was considerably more pronounced for PrDC than GDC, and was explained by the considerably larger change in ionic radius for Pr upon reduction. XANES absorption experiments at the Ce and Pr L3-edge showed that the changes observed upon reduction of the Pr-containing samples resulted mostly from the formation of Pr3+ rather than Ce3+, and supported the previously reported proposal that Pr3+ has a stabilizing effect on Ce4+.In this work, nanostructured LnxCe1-xO2-δ (Ln: Gd and Pr; x = 0.1 and 0.2) spheres were synthesized by microwave assisted hydrothermal homogeneous co-precipitation and their properties were characterized by synchrotron radiation XRD, X-ray absorption near-edge spectroscopy (XANES) and scanning and high-resolution electron microscopy (SEM and HRTEM). In situ XRD and XANES experiments were carried out under reducing and oxidizing conditions in order to investigate the redox behaviour of these

  12. 7 CFR 33.4 - Carrier.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS REGULATIONS... private carrier, including, but not limited to trucks, railroads, airplanes, vessels, tramp or...

  13. Useful Life Prediction for Payload Carrier Hardware

    NASA Technical Reports Server (NTRS)

    Ben-Arieh, David

    2002-01-01

    The Space Shuttle has been identified for use through 2020. Payload carrier systems will be needed to support missions through the same time frame. To support the future decision making process with reliable systems, it is necessary to analyze design integrity, identify possible sources of undesirable risk and recognize required upgrades for carrier systems. This project analyzed the information available regarding the carriers and developed the probability of becoming obsolete under different scenarios. In addition, this project resulted in a plan for an improved information system that will improve monitoring and control of the various carriers. The information collected throughout this project is presented in this report as process flow, historical records, and statistical analysis.

  14. NASA's Original Shuttle Carrier Departs Dryden

    NASA Video Gallery

    NASA's Space Shuttle Carrier Aircraft (SCA) No. 905, departed NASA's Dryden Flight Research Center on Oct. 24, 2012 for the final time, ending a 38-year association with the NASA field center at Ed...

  15. Multiple sclerosis in an adrenoleukodystrophy carrier

    PubMed Central

    Jenkins, Thomas; Sarasamma, Priya; Gillett, Godfrey; Coley, Stuart; Sharrack, Basil

    2011-01-01

    X-linked adrenoleukodystrophy (X-ALD) is a rare inherited metabolic disorder, in which accumulation of very long chain fatty acids (VLCFAs) results in damage to the central nervous system. As the disease is X-linked, males are affected severely, but female carriers may also present with neurological symptoms. We report the case of a young adult female, who presented with episodic sensorimotor symptoms. Although she was a heterozygous female carrier of X-ALD, subsequent investigations confirmed a diagnosis of multiple sclerosis (MS). To the best of our knowledge, this is the first reported case of a female X-ALD carrier in which the clinical features were more consistent with co-existent MS than ALD-related pathology. The case serves as a reminder that alternative, more common diagnoses should also be considered in carriers of rare neurological syndromes. PMID:24765366

  16. Precise frequency calibration using television video carriers

    NASA Technical Reports Server (NTRS)

    Burkhardt, Edward E.

    1990-01-01

    The availability of inexpensive and quick precise frequency calibration methods is limited. VLF and GPS do offer precise calibration. However, antenna placement, cost of equipment, and calibration time place many restrictions on the user. The USNO maintained line-10 television Time of Coincidence (TOC) of station WTTG, channel 5, Washington, DC requires a frequency stable video carrier. This video carrier, 77.24 MHz is controlled by the same cesium beam standard controlling the TOC of line-10. Excellent frequency comparisons against this video carrier have been accomplished at 95 miles (153 km). With stable propagation and a three foot wire antenna, a part in 10(exp 9) can be determined in a few minutes. Inexpensive field equipment with a synthesized 1 kHz offset from the video carrier offers parts in 10(exp 11) calibrations in a few minutes using an oscilloscope as a phase comparator.

  17. Minority carrier lifetime in indium phosphide

    NASA Technical Reports Server (NTRS)

    Jenkins, Phillip; Landis, Geoffrey A.; Weinberg, Irving; Kneisel, Keith

    1991-01-01

    Transient photoluminescence is used to measure the minority carrier lifetime on n-type and p-type InP wafers. The measurements show that unprocessed InP wafers have very high minority carrier lifetimes. Lifetimes of 200 ns and 700 ns were observed for lightly-doped p- and n-type material respectively. Lifetimes over 5 ns were found in heavily doped n-type material.

  18. Hot-Carrier Seebeck Effect: Diffusion and Remote Detection of Hot Carriers in Graphene.

    PubMed

    Sierra, Juan F; Neumann, Ingmar; Costache, Marius V; Valenzuela, Sergio O

    2015-06-10

    We investigate hot carrier propagation across graphene using an electrical nonlocal injection/detection method. The device consists of a monolayer graphene flake contacted by multiple metal leads. Using two remote leads for electrical heating, we generate a carrier temperature gradient that results in a measurable thermoelectric voltage V(NL) across the remaining (detector) leads. Due to the nonlocal character of the measurement, V(NL) is exclusively due to the Seebeck effect. Remarkably, a departure from the ordinary relationship between Joule power P and V(NL), V(NL) ∼ P, becomes readily apparent at low temperatures, representing a fingerprint of hot-carrier dominated thermoelectricity. By studying V(NL) as a function of bias, we directly determine the carrier temperature and the characteristic cooling length for hot-carrier propagation, which are key parameters for a variety of new applications that rely on hot-carrier transport. PMID:25950746

  19. Radio Science Measurements with Suppressed Carrier

    NASA Technical Reports Server (NTRS)

    Asmar, Sami; Divsalar, Dariush; Oudrhiri, Kamal

    2013-01-01

    Radio Science started when it became apparent with early Solar missions that occultations by planetary atmospheres would affect the quality of radio communications. Since then the atmospheric properties and other aspects of planetary science, solar science, and fundamental physics were studied by scientists. Radio Science data was always extracted from a received pure residual carrier (without data modulation). For some missions, it is very desirable to obtain Radio Science data from a suppressed carrier modulation. In this paper we propose a method to extract Radio Science data when a coded suppressed carrier modulation is used in deep space communications. Type of modulation can be BPSK, QPSK, OQPSK, MPSK or even GMSK. However we concentrate mostly on BPSK modulation. The proposed method for suppressed carrier simply tries to wipe out data that acts as an interference for Radio Science measurements. In order to measure the estimation errors in amplitude and phase of the Radio Science data we use Cramer-Rao bound (CRB). The CRB for the suppressed carrier modulation with non-ideal data wiping is then compared with residual carrier modulation under the same noise condition. The method of derivation of CRB for non-ideal data wiping is an innovative method that presented here. Some numerical results are provided for coded system.

  20. Materials flight experiment carrier capability and future flight experiments on Hitchhiker-M carrier program

    NASA Astrophysics Data System (ADS)

    Davis, D.

    1993-10-01

    The CMSS has designed, fabricated, and qualified a unique Materials FLight EXperiment (MFLEX) carrier. The MFLEX is a reusable materials experiment carrier designed to support a wide array of sensors that measure synergistic effects on candidate space materials in Low Earth Orbit (LEO). The MFLEX can be integrated on a variety of launch vehicles/carriers and multiple units can be networked to optimize the surface area of carriers such as the Hitchhiker-M currently being built by the Goddard Space Flight Center (GSFC).

  1. Materials flight experiment carrier capability and future flight experiments on Hitchhiker-M carrier program

    NASA Technical Reports Server (NTRS)

    Davis, D.

    1993-01-01

    The CMSS has designed, fabricated, and qualified a unique Materials FLight EXperiment (MFLEX) carrier. The MFLEX is a reusable materials experiment carrier designed to support a wide array of sensors that measure synergistic effects on candidate space materials in Low Earth Orbit (LEO). The MFLEX can be integrated on a variety of launch vehicles/carriers and multiple units can be networked to optimize the surface area of carriers such as the Hitchhiker-M currently being built by the Goddard Space Flight Center (GSFC).

  2. Simultaneous determinations of zirconium, hafnium, yttrium and lanthanides in seawater according to a co-precipitation technique onto iron-hydroxide.

    PubMed

    Raso, Maria; Censi, Paolo; Saiano, Filippo

    2013-11-15

    Very low concentrations (pg mL(-1) or sub-pg mL(-1) level) along with the high salinity are the main problems in determining trace metal contents in seawater. This problem is mainly considered for investigations of naturally occurring YLOID (Y and Lanthanides) and Zr and Hf in order to provide precise and accurate results. The inductively coupled plasma mass spectrometry (ICP-MS), both in high and low resolution, offers many advantages including simultaneous analyses of all elements and their quantitative determination with detection limits of the order of pg mL(-1). However in the analysis of YLOID in seawater, a better determination needs an efficient combination of ICP-MS measurement with a pre-concentration technique. To perform an ultra-trace analysis in seawater, we have validated an analytical procedure involving an improved modified co-precipitation on iron hydroxides to ensure the simultaneous quantitative recovery of YLOID, Zr and Hf contents with measurement by a quadrupole ICP-MS. The validity of the method was assessed through a series of co-precipitation experiments and estimation of several quality control parameters for method validation, namely working range and its linearity, detection limit, quantification limit, precision and spike recoveries, and the methodological blank choice, are introduced, evaluated and discussed. Analysis of NASS-6, is the first report on the latest seawater reference material for YLOID, hafnium and zirconium.

  3. XRD line-broadening characteristics of M-oxides (M = Mg, Mg-Al, Y, Fe) nanoparticles produced by coprecipitation method

    NASA Astrophysics Data System (ADS)

    Pratapa, S.; Susanti, L.; Insany, Y. A. S.; Alfiati, Z.; Hartono, B.; Mashuri, Taufiq, Ahmad; Fuad, Abdullah; Triwikantoro, Baqiya, M. A.; Purwaningsih, S.; Yahya, E.; Darminto

    2010-10-01

    Simple coprecipitation method has been used to produce nanoparticles of MgO (magnesia), MgOṡAl2O3 (spinel), Y2O3 (yttria) and Fe3O4 (ferrite). The raw materials were, in respective, magnesium powder, magnesium and aluminium powders, ytrria powder, and natural sand. The coprecipitation included the use of suitable acid and base to dissolve the powders or sand and to produce precipitates, as well as the use of water to wash and purify the precipitates, and drying at relatively low temperatures, namely lower than 100° C, followed by heating at 450° C, 750° C, 600° C and 200° C to produce magnesia, spinel, yttria and ferrite nanopowders, respectively. X-ray diffractometry was used to characterise the purity and nanocrystallinity of the final powders. It was found qualitatively that the powders were of high purity. Further line-broadening analysis using single-line and Rietveld-based softwares was performed to reveal the nanocrystallinity of the powders. Different line breadth values were found for the powders, indicating different crystallite sizes. It was also found that, particularly for spinel and yttria, the diffraction peaks exhibited `longer' tails, indicating broader crystallite size distribution. The average crystallite size for the powders ranged from 3 to 70 nm. The results could then be used as `fingerprints' for nanocrystallinity using x-ray diffractometry. The XRD crystallite sizes for yttria and ferrite nanocrystals are in fair agreement with their counterparts from electron microscopy observation.

  4. Theoretical and experimental study of the incorporation of tobramycin and strontium-ions into hydroxyapatite by means of co-precipitation

    NASA Astrophysics Data System (ADS)

    Wang, Baochang; Lilja, Mirjam; Ma, Taoran; Sörensen, Jan; Steckel, Hartwig; Ahuja, Rajeev; Strømme, Maria

    2014-09-01

    Antibiotic incorporation into hydroxyapatite (HA) coatings by co-precipitation and the impact of bone relevant doping elements on the adsorption kinetics are investigated from both theoretical and experimental points of view. Tobramycin interactions with bioactive TiO2 and HA surfaces are analyzed using density functional theory. According to the calculations, the drug molecule has larger adsorption energy than the Ca+ ion on both surfaces under study in Phosphate Buffered Saline (PBS). The results support the experimental observations that HA nucleation and growth are strongly limited on TiO2 surfaces in the presence of clinically relevant antibiotic concentrations in PBS. The drug molecule is more likely to adopt parallel arrangement onto the HA surface, as the adsorption energy of such arrangement is higher compared to a perpendicular one. Strontium substitution of the HA surface is found to results in a weaker drug-surface interaction, and leads also to a decrease in coating thickness. However, the presence of strontium gives rise to a coating morphology with enhanced drug incorporation capacity and slower antibiotic release compared to non-substituted, co-precipitated counterparts. Our theoretical calculation results were found to be in excellent agreement with experimental data and provide a powerful tool to understand the interaction mechanism between drug and different surface chemistries necessary for development of future versatile orthopedic and dental implant surfaces.

  5. Highly selective hydrogenation of CO2 to methanol over CuO-ZnO-ZrO2 catalysts prepared by a surfactant-assisted co-precipitation method

    NASA Astrophysics Data System (ADS)

    Li, Li; Mao, Dongsen; Yu, Jun; Guo, Xiaoming

    2015-04-01

    A series of CuO-ZnO-ZrO2 catalysts are synthesized by a surfactant-assisted co-precipitation method and tested for the synthesis of methanol from CO2 hydrogenation. The effects of calcination temperature on the physicochemical properties of as-prepared catalysts are investigated extensively by TG-DSC, N2 adsorption/desorption, XRD, N2O chemisorption, SEM/TEM, EDX, XPS, TPR, H2-TPD and CO2-TPD techniques. The results show that the size of copper particles increases with the increase in calcination temperature, leading to the decrease in turnover frequency (TOF) for methanol formation. Moreover, compared with the counterparts prepared by the conventional co-precipitation method, the CuO-ZnO-ZrO2 catalysts prepared by this novel method show significantly high methanol selectivity. The superior property of the prepared CuO-ZnO-ZrO2 catalyst can be attributed to the formation of more amounts of Cu-ZnOx and/or Cu-ZrOx species resulted from the homogeneous element distribution, intimate interface contact of Cu species with ZnO and/or ZrO2, and to porous structure with larger pore size.

  6. Incorporation of transition metals into Mg-Al layered double hydroxides: Coprecipitation of cations vs. their pre-complexation with an anionic chelator

    SciTech Connect

    Tsyganok, Andrey; Sayari, Abdelhamid . E-mail: Abdel.Sayari@science.uottawa.ca

    2006-06-15

    A comparative study on two different methods for preparing Mg-Al layered double hydroxides (LDH) containing various divalent transition metals M (M=Co, Ni, Cu) has been carried out. The first (conventional) method involved coprecipitation of divalent metals M(II) with Mg(II) and Al(III) cations using carbonate under basic conditions. The second approach was based on the ability of transition metals to form stable anionic chelates with edta{sup 4-} (edta{sup 4-}=ethylenediaminetetraacetate) that were synthesized and further introduced into LDH by coprecipitation with Mg and Al. The synthesized LDHs were characterized by X-ray diffraction (XRD) and X-ray fluorescence (XRF) methods, thermogravimetry with mass-selective detection of decomposition products (TG-MSD), Fourier transform infrared (FTIR) and Raman spectroscopy techniques. The results obtained were discussed in terms of efficiency of transition metal incorporation into the LDH structure, thermal stability of materials and the ability of metal chelates to intercalate the interlayer space of Mg-Al LDH. Vibrational spectroscopy studies confirmed that the integrity of the metal chelates was preserved upon incorporation into the LDH. - Graphical abstract: Two ways for introducing transition metals M(II) into Mg-Al layered double hydroxides (MY{sup 2-} denotes the edta chelate of transition metal M(II)).0.

  7. Production of Ba(Zn{sub 1/3}Nb{sub 2/3})O{sub 3} ceramic by coprecipitation

    SciTech Connect

    Mergen, A. Sert, D.

    2012-01-15

    A simple coprecipitation technique was successfully applied for the preparation of pure, nanosized, single phase Ba(Zn{sub 1/3}Nb{sub 2/3})O{sub 3} microwave dielectric ceramic powders. Barium, zinc and niobium ions were precipitated as hydroxide under basic conditions using aqueous sodium hydroxide solution and single phase Ba(Zn{sub 1/3}Nb{sub 2/3})O{sub 3} ceramic was produced at 800 Degree-Sign C. TEM revealed an average particle size of around 100 nm for the calcined powders. The samples sintered at 1250 Degree-Sign C for 4 h had a relatively high density and fine grain sizes. While the dielectric constant of ceramics varied between 37.5 and 39.8 the dielectric losses were lower than 4 Multiplication-Sign 10{sup -3} at frequency range of 1 kHz-2 MHz between 20 and 200 Degree-Sign C. - Highlights: Black-Right-Pointing-Pointer Production of BZN by coprecipitation. Black-Right-Pointing-Pointer Nanoscale BZN powder. Black-Right-Pointing-Pointer Dielectric properties of BZN.

  8. Gelatin-apatite bone mimetic co-precipitates incorporated within biopolymer matrix to improve mechanical and biological properties useful for hard tissue repair

    PubMed Central

    Won, Jong-Eun; El-Fiqi, Ahmed; Jegal, Seung-Hwan; Han, Cheol-Min; Lee, Eun-Jung; Knowles, Jonathan C

    2014-01-01

    Synthetic biopolymers are commonly used for the repair and regeneration of damaged tissues. Specifically targeting bone, the composite approach of utilizing inorganic components is considered promising in terms of improving mechanical and biological properties. We developed gelatin-apatite co-precipitates which mimic the native bone matrix composition within poly(lactide-co-caprolactone) (PLCL). Ionic reaction of calcium and phosphate with gelatin molecules enabled the co-precipitate formation of gelatin-apatite nanocrystals at varying ratios. The gelatin-apatite precipitates formed were carbonated apatite in nature, and were homogeneously distributed within the gelatin matrix. The incorporation of gelatin-apatite significantly improved the mechanical properties, including tensile strength, elastic modulus and elongation at break, and the improvement was more pronounced as the apatite content increased. Of note, the tensile strength increased to as high as 45 MPa (a four-fold increase vs. PLCL), the elastic modulus was increased up to 1500 MPa (a five-fold increase vs. PLCL), and the elongation rate was ∼240% (twice vs. PLCL). These results support the strengthening role of the gelatin-apatite precipitates within PLCL. The gelatin-apatite addition considerably enhanced the water affinity and the acellular mineral-forming ability in vitro in simulated body fluid; moreover, it stimulated cell proliferation and osteogenic differentiation. Taken together, the GAp-PLCL nanocomposite composition is considered to have excellent mechanical and biological properties, which hold great potential for use as bone regenerative matrices. PMID:23985536

  9. Synthesis of aqueous suspensions of magnetic nanoparticles with the co-precipitation of iron ions in the presence of aspartic acid

    NASA Astrophysics Data System (ADS)

    Pušnik, Klementina; Goršak, Tanja; Drofenik, Miha; Makovec, Darko

    2016-09-01

    There is increasing demand for the production of large quantities of aqueous suspensions of magnetic iron-oxide nanoparticles. Amino acids are one possible type of inexpensive, nontoxic, and biocompatible molecules that can be used as the surfactants for the preparation of stable suspensions. This preparation can be conducted in a simple, one-step process based on the co-precipitation of Fe3+/Fe2+ ions in the presence of the amino acid. However, the presence of this amino acid changes the mechanism of the magnetic nanoparticles' formation. In this investigation we analyzed the influence of aspartic amino acid (Asp) on the formation of magnetic iron-oxide nanoparticles during the co-precipitation. The process of the nanoparticles' formation was followed using a combination of TEM, x-ray diffractometry, magnetic measurements, in-situ FT-IR spectroscopy, and chemical analysis, and compared with the formation of nanoparticles without the Asp. The Asp forms a coordination complex with the Fe3+ ions, which impedes the formation of the intermediate iron oxyhydroxide phase and suppresses the growth of the final magnetic iron-oxide nanoparticles. Slower reaction kinetics can lead to the formation of nonmagnetic secondary phases. The aspartic-acid-absorbed nanoparticles can be dispersed to form relatively concentrated aqueous suspensions displaying a good colloidal stability at an increased pH.

  10. Influence of adsorption versus coprecipitation on the retention of rice straw-derived dissolved organic carbon and subsequent reducibility of Fe-DOC systems

    NASA Astrophysics Data System (ADS)

    Sodano, Marcella; Lerda, Cristina; Martin, Maria; Celi, Luisella; Said-Pullicino, Daniel

    2016-04-01

    The dissimilatory reduction of Fe oxides is the main organic C-consuming process in paddy soils under anoxic conditions. The contribution of Fe(III) reduction to anaerobic C mineralization depends on many factors, but most importantly on the bioavailability of labile organic matter and a reducible Fe pool as electron donors and acceptors, respectively. On the other hand, the strong affinity of these minerals for organic matter and their capability of protecting it against microbial decomposition is well known. Natural Fe oxides in these soils may therefore play a key role in determining the C source/sink functions of these agro-ecosystems. Apart from contributing to C stabilization, the interaction between Fe oxides and dissolved organic C (DOC) may influence the structure and reactivity of these natural oxides, and selectively influence the chemical properties of DOC. Indeed, Fe-DOC associations may not only reduce the availability of DOC, but may also limit the microbial reduction of Fe oxides under anoxic conditions. In fact, the accessibility of these minerals to microorganisms, extracellular enzymes, redox active shuttling compound or reducing agents may be impeded by the presence of sorbed organic matter. In soils that are regularly subjected to fluctuations in redox conditions the interaction between DOC and Fe oxides may not only involve organic coatings on mineral surfaces, but also Fe-DOC coprecipitates that form during the rapid oxidation of soil solutions containing important amounts of DOC and Fe(II). However, little is known on how these processes influence DOC retention, and the structure and subsequent reducibility of these Fe-DOC associations. We hypothesized that the nature and extent of the interaction between DOC and Fe oxides may influence the accessibility of the bioavailable Fe pool and consequently its reducibility. We tested this hypothesis by synthesizing a series of Fe-DOC systems with increasing C:Fe ratios prepared by either surface

  11. Differential Analysis of the Nasal Microbiome of Pig Carriers or Non-Carriers of Staphylococcus aureus.

    PubMed

    Espinosa-Gongora, Carmen; Larsen, Niels; Schønning, Kristian; Fredholm, Merete; Guardabassi, Luca

    2016-01-01

    Staphylococcus aureus is presently regarded as an emerging zoonotic agent due to the spread of specific methicillin-resistant S. aureus (MRSA) clones in pig farms. Studying the microbiota can be useful for the identification of bacteria that antagonize such opportunistic veterinary and zoonotic pathogen in animal carriers. The aim of this study was to determine whether the nasal microbiome of pig S. aureus carriers differs from that of non-carriers. The V3-V5 region of the 16S rRNA gene was sequenced from nasal swabs of 44 S. aureus carriers and 56 non-carriers using the 454 GS FLX titanium system. Carriers and non-carriers were selected on the basis of quantitative longitudinal data on S. aureus carriage in 600 pigs sampled at 20 Danish herds included in two previous studies in Denmark. Raw sequences were analysed with the BION meta package and the resulting abundance matrix was analysed using the DESeq2 package in R to identify operational taxonomic units (OTUs) with differential abundance between S. aureus carriers and non-carriers. Twenty OTUs were significantly associated to non-carriers, including species with known probiotic potential and antimicrobial effect such as lactic acid-producing isolates described among Leuconostoc spp. and some members of the Lachnospiraceae family, which is known for butyrate production. Further 5 OTUs were significantly associated to carriage, including known pathogenic bacteria such as Pasteurella multocida and Klebsiella spp. Our results show that the nasal microbiome of pigs that are not colonized with S. aureus harbours several species/taxa that are significantly less abundant in pig carriers, suggesting that the nasal microbiota may play a role in the individual predisposition to S. aureus nasal carriage in pigs. Further research is warranted to isolate these bacteria and assess their possible antagonistic effect on S. aureus for the pursuit of new strategies to control MRSA in pig farming. PMID:27509169

  12. Differential Analysis of the Nasal Microbiome of Pig Carriers or Non-Carriers of Staphylococcus aureus

    PubMed Central

    Espinosa-Gongora, Carmen; Larsen, Niels; Schønning, Kristian; Fredholm, Merete; Guardabassi, Luca

    2016-01-01

    Staphylococcus aureus is presently regarded as an emerging zoonotic agent due to the spread of specific methicillin-resistant S. aureus (MRSA) clones in pig farms. Studying the microbiota can be useful for the identification of bacteria that antagonize such opportunistic veterinary and zoonotic pathogen in animal carriers. The aim of this study was to determine whether the nasal microbiome of pig S. aureus carriers differs from that of non-carriers. The V3-V5 region of the 16S rRNA gene was sequenced from nasal swabs of 44 S. aureus carriers and 56 non-carriers using the 454 GS FLX titanium system. Carriers and non-carriers were selected on the basis of quantitative longitudinal data on S. aureus carriage in 600 pigs sampled at 20 Danish herds included in two previous studies in Denmark. Raw sequences were analysed with the BION meta package and the resulting abundance matrix was analysed using the DESeq2 package in R to identify operational taxonomic units (OTUs) with differential abundance between S. aureus carriers and non-carriers. Twenty OTUs were significantly associated to non-carriers, including species with known probiotic potential and antimicrobial effect such as lactic acid-producing isolates described among Leuconostoc spp. and some members of the Lachnospiraceae family, which is known for butyrate production. Further 5 OTUs were significantly associated to carriage, including known pathogenic bacteria such as Pasteurella multocida and Klebsiella spp. Our results show that the nasal microbiome of pigs that are not colonized with S. aureus harbours several species/taxa that are significantly less abundant in pig carriers, suggesting that the nasal microbiota may play a role in the individual predisposition to S. aureus nasal carriage in pigs. Further research is warranted to isolate these bacteria and assess their possible antagonistic effect on S. aureus for the pursuit of new strategies to control MRSA in pig farming. PMID:27509169

  13. 14 CFR 389.24 - Foreign air carriers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Foreign air carriers. 389.24 Section 389.24...) ORGANIZATION FEES AND CHARGES FOR SPECIAL SERVICES Filing and Processing License Fees § 389.24 Foreign air carriers. A foreign air carrier, or such carriers, if from the same country, acting jointly, may apply...

  14. 14 CFR 389.24 - Foreign air carriers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Foreign air carriers. 389.24 Section 389.24...) ORGANIZATION FEES AND CHARGES FOR SPECIAL SERVICES Filing and Processing License Fees § 389.24 Foreign air carriers. A foreign air carrier, or such carriers, if from the same country, acting jointly, may apply...

  15. 47 CFR 64.1190 - Preferred carrier freezes.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 3 2014-10-01 2014-10-01 false Preferred carrier freezes. 64.1190 Section 64.1190 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES (CONTINUED) MISCELLANEOUS RULES RELATING TO COMMON CARRIERS Changes in Preferred Telecommunications Service Providers § 64.1190 Preferred carrier freezes....

  16. 14 CFR 389.24 - Foreign air carriers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Foreign air carriers. 389.24 Section 389.24...) ORGANIZATION FEES AND CHARGES FOR SPECIAL SERVICES Filing and Processing License Fees § 389.24 Foreign air carriers. A foreign air carrier, or such carriers, if from the same country, acting jointly, may apply...

  17. 27 CFR 28.93 - Carrier to be designated.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Carrier to be designated... to a Manufacturing Bonded Warehouse § 28.93 Carrier to be designated. The name of the carrier or carriers to be used in transporting the distilled spirits from the bonded premises of the distilled...

  18. 27 CFR 28.93 - Carrier to be designated.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Carrier to be designated... to a Manufacturing Bonded Warehouse § 28.93 Carrier to be designated. The name of the carrier or carriers to be used in transporting the distilled spirits from the bonded premises of the distilled...

  19. 27 CFR 28.93 - Carrier to be designated.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Carrier to be designated... to a Manufacturing Bonded Warehouse § 28.93 Carrier to be designated. The name of the carrier or carriers to be used in transporting the distilled spirits from the bonded premises of the distilled...

  20. 27 CFR 28.93 - Carrier to be designated.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Carrier to be designated... to a Manufacturing Bonded Warehouse § 28.93 Carrier to be designated. The name of the carrier or carriers to be used in transporting the distilled spirits from the bonded premises of the distilled...

  1. 27 CFR 28.93 - Carrier to be designated.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Carrier to be designated... to a Manufacturing Bonded Warehouse § 28.93 Carrier to be designated. The name of the carrier or carriers to be used in transporting the distilled spirits from the bonded premises of the distilled...

  2. 76 FR 32390 - Motor Carrier Safety Advisory Committee Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-06

    ... Federal Motor Carrier Safety Administration Motor Carrier Safety Advisory Committee Public Meeting AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT. ACTION: Notice of Motor Carrier Safety Advisory... MCSAC will complete action on Task 11-01, regarding Patterns of Safety Violations by Motor...

  3. 75 FR 2923 - Motor Carrier Safety Advisory Committee Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-19

    ... sessions announced on January 5, 2010 (75 FR 285), and elsewhere in today's Federal Register, and to... Federal Motor Carrier Safety Administration Motor Carrier Safety Advisory Committee Public Meeting AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT. ACTION: Notice of Motor Carrier Safety...

  4. 46 CFR 565.3 - Classification as controlled carrier.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 9 2014-10-01 2014-10-01 false Classification as controlled carrier. 565.3 Section 565... MARITIME PRACTICES CONTROLLED CARRIERS § 565.3 Classification as controlled carrier. (a) Notification. The... States and will notify any ocean common carrier of any change in its classification as a...

  5. 46 CFR 565.3 - Classification as controlled carrier.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 9 2012-10-01 2012-10-01 false Classification as controlled carrier. 565.3 Section 565... MARITIME PRACTICES CONTROLLED CARRIERS § 565.3 Classification as controlled carrier. (a) Notification. The... States and will notify any ocean common carrier of any change in its classification as a...

  6. 46 CFR 565.3 - Classification as controlled carrier.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 9 2011-10-01 2011-10-01 false Classification as controlled carrier. 565.3 Section 565... MARITIME PRACTICES CONTROLLED CARRIERS § 565.3 Classification as controlled carrier. (a) Notification. The... States and will notify any ocean common carrier of any change in its classification as a...

  7. 46 CFR 565.3 - Classification as controlled carrier.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 9 2013-10-01 2013-10-01 false Classification as controlled carrier. 565.3 Section 565... MARITIME PRACTICES CONTROLLED CARRIERS § 565.3 Classification as controlled carrier. (a) Notification. The... States and will notify any ocean common carrier of any change in its classification as a...

  8. 46 CFR 565.3 - Classification as controlled carrier.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 9 2010-10-01 2010-10-01 false Classification as controlled carrier. 565.3 Section 565... MARITIME PRACTICES CONTROLLED CARRIERS § 565.3 Classification as controlled carrier. (a) Notification. The... States and will notify any ocean common carrier of any change in its classification as a...

  9. 47 CFR 64.1140 - Carrier liability for slamming.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 3 2010-10-01 2010-10-01 false Carrier liability for slamming. 64.1140 Section 64.1140 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES... Providers § 64.1140 Carrier liability for slamming. (a) Carrier Liability for Charges. Any...

  10. 47 CFR 73.1540 - Carrier frequency measurements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 73.1540 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES... measurements. (a) The carrier frequency of each AM and FM station and the visual carrier frequency and the difference between the visual carrier and the aural carrier or center frequency of each TV and Class A...

  11. Theileria annulata: carrier state and immunity.

    PubMed

    Ilhan, T; Williamson, S; Kirvar, E; Shiels, B; Brown, C G

    1998-06-29

    Recovery from primary infection of Theileria annulata results in the development of a persistent carrier state in the vertebrate host. The carrier state is of great importance in the maintenance of the life cycle by alternate tick/cattle challenge and both contributes to and may be necessary for maintenance of immunity. Therefore, an accurate determination of carrier animals could be useful in determining immune status and may allow the necessary control measures to be implemented. Detailed information on the carrier state of animals following immunization with attenuated cell lines is lacking. In this study, relationship between immune response, persistence of the parasite, and the antibody response has been investigated. Calves were infected with T. annulata sporozoites, low passage (non-attenuated) or high passage (attenuated, vaccine) cell lines and later challenged with a lethal dose of heterologous sporozoites. The presence and persistence of the parasite were monitored by PCR using primers derived from genes coding for ssrRNA and a 30 kDa major merozoite surface protein, by Giemsa stained blood smears to detect the presence of piroplasms and also by attempting to establish infected mononuclear cell cultures from venous blood. Antibody responses were measured by indirect ELISA using a merozoite recombinant antigen and IFAT using piroplasm and macroschizont antigens. Results showed that there was an evident relationship between the persistence of carrier status, antibody response in ELISA and immune response to challenge.

  12. Extracting hot carriers from photoexcited semiconductor nanocrystals

    SciTech Connect

    Zhu, Xiaoyang

    2014-12-10

    This research program addresses a fundamental question related to the use of nanomaterials in solar energy -- namely, whether semiconductor nanocrystals (NCs) can help surpass the efficiency limits, the so-called “Shockley-Queisser” limit, in conventional solar cells. In these cells, absorption of photons with energies above the semiconductor bandgap generates “hot” charge carriers that quickly “cool” to the band edges before they can be utilized to do work; this sets the solar cell efficiency at a limit of ~31%. If instead, all of the energy of the hot carriers could be captured, solar-to-electric power conversion efficiencies could be increased, theoretically, to as high as 66%. A potential route to capture this energy is to utilize semiconductor nanocrystals. In these materials, the quasi-continuous conduction and valence bands of the bulk semiconductor become discretized due to confinement of the charge carriers. Consequently, the energy spacing between the electronic levels can be much larger than the highest phonon frequency of the lattice, creating a “phonon bottleneck” wherein hot-carrier relaxation is possible via slower multiphonon emission. For example, hot-electron lifetimes as long as ~1 ns have been observed in NCs grown by molecular beam epitaxy. In colloidal NCs, long lifetimes have been demonstrated through careful design of the nanocrystal interfaces. Due to their ability to slow electronic relaxation, semiconductor NCs can in principle enable extraction of hot carriers before they cool to the band edges, leading to more efficient solar cells.

  13. Carrier relaxation dynamics in heavy fermion compounds

    SciTech Connect

    Demsar, J.; Tracy, L. A.; Averitt, R. D.; Trugman, S. A.; Sarrao, John L.,; Taylor, Antoinette J.,

    2002-01-01

    The first femtosecond carrier relaxation dynamics studies in heavy fermion compounds are presented. The carrier relaxation time shows a dramatic hundred-fold increase below the Kondo temperature revealing a dramatic sensitivity to the electronic density of states near the Fermi level. Femtosecond time-resolved optical spectroscopy is an excellent experimental alternative to conventional spectroscopic methods that probe the low energy electronic structure in strongly correlated electron systems. In particular, it has been shown that carrier relaxation dynamics are very sensitive to changes in the low energy density of states (e.g. associated with the formation of a low energy gap or pseudogap) providing new insights into the low energy electronic structure in these materials. In this report we present the first studies of carrier relaxation dynamics in heavy fermion (HF) systems by means of femtosecond time-resolved optical spectroscopy. Our results show that the carrier relaxation dynamics, below the Kondo temperature (T{sub K}), are extremely sensitive to the low energy density of states (DOS) near the Ferini level to which localized f-moments contribute. Specifically, we have performed measurements of the photoinduced reflectivity {Delta}R/R dynamics as a function of temperature and excitation intensity on the series of HF compounds YbXCu{sub 4} (X = Ag, Cd, In) in comparison to their non-magnetic counterparts LuXCu{sub 4}.

  14. 14 CFR 158.23 - Consultation with air carriers and foreign air carriers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Consultation with air carriers and foreign air carriers. 158.23 Section 158.23 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT... funding by PFC's; (2) The PFC level for each project, the proposed charge effective date, the...

  15. Spectroscopy of carrier multiplication in nanocrystals.

    PubMed

    Bruhn, Benjamin; Limpens, Rens; Chung, Nguyen Xuan; Schall, Peter; Gregorkiewicz, Tom

    2016-01-01

    Carrier multiplication in nanostructures promises great improvements in a number of widely used technologies, among others photodetectors and solar cells. The decade since its discovery was ridden with fierce discussions about its true existence, magnitude, and mechanism. Here, we introduce a novel, purely spectroscopic approach for investigation of carrier multiplication in nanocrystals. Applying this method to silicon nanocrystals in an oxide matrix, we obtain an unambiguous spectral signature of the carrier multiplication process and reveal details of its size-dependent characteristics-energy threshold and efficiency. The proposed method is generally applicable and suitable for both solid state and colloidal samples, as well as for a great variety of different materials. PMID:26852922

  16. Nanogel Carrier Design for Targeted Drug Delivery

    PubMed Central

    Eckmann, D. M.; Composto, R. J.; Tsourkas, A.; Muzykantov, V. R.

    2014-01-01

    Polymer-based nanogel formulations offer features attractive for drug delivery, including ease of synthesis, controllable swelling and viscoelasticity as well as drug loading and release characteristics, passive and active targeting, and the ability to formulate nanogel carriers that can respond to biological stimuli. These unique features and low toxicity make the nanogels a favorable option for vascular drug targeting. In this review, we address key chemical and biological aspects of nanogel drug carrier design. In particular, we highlight published studies of nanogel design, descriptions of nanogel functional characteristics and their behavior in biological models. These studies form a compendium of information that supports the scientific and clinical rationale for development of this carrier for targeted therapeutic interventions. PMID:25485112

  17. Inorganic Nanomaterials as Carriers for Drug Delivery.

    PubMed

    Chen, Shizhu; Hao, Xiaohong; Liang, Xingjie; Zhang, Qun; Zhang, Cuimiao; Zhou, Guoqiang; Shen, Shigang; Jia, Guang; Zhang, Jinchao

    2016-01-01

    For safe and effective therapy, drugs must be delivered efficiently and with minimal systemic side effects. Nanostructured drug carriers enable the delivery of small-molecule drugs as well as nucleic acids and proteins. Inorganic nanomaterials are ideal for drug delivery platforms due to their unique physicochemical properties, such as facile preparation, good storage stability and biocompatibility. Many inorganic nanostructure-based drug delivery platforms have been prepared. Although there are still many obstacles to overcome, significant advances have been made in recent years. This review focuses on the status and development of inorganic nanostructures, including silica, quantum dots, gold, carbon-based and magnetic iron oxide-based nanostructures, as carriers for chemical and biological drugs. We specifically highlight the extensive use of these inorganic drug carriers for cancer therapy. Finally, we discuss the most important areas in the field that urgently require further study. PMID:27301169

  18. Nonuniform carrier distribution in semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Evankow, Joseph David, Jr.

    This work discusses the experimental results and theoretical analysis of the longitudinal distribution of the spontaneous emission, amplified spontaneous emission, hole-electron pairs, and gain in semiconductor optical amplifiers. A novel, yet simple, technique was developed enabling, for the first time, the measurement of these distributions. This was accomplished with a high degree of spatial resolution using a single-mode micro-lensed fiber tip positioned perpendicular to the active region and moved longitudinally along the stripe. The cornerstone of this study centers on the theoretical analysis of the small portion of the isotropic spontaneous emission, emanating from the optical cavity, which is captured by the lensed fiber. Spectral as well as integrated power measurements were made along the length of the cavity. These spectral and integrated power measurements provide a direct link to the carrier concentration and gain along the optical cavity. The distribution of this spontaneous emission along the amplifier, and its relationship to other parameters, provide information about the carriers. Since the common mode of operation for linear optical amplifiers is deep in saturation, the devices in this study were analyzed in regimes significantly below the small-signal gain. While large carrier density non- uniformity occur with output powers equal to or greater than Psat, a significant amount can occur in amplifiers even with small input signals. In these amplifiers, the higher carder concentrations produce much higher internal gain coefficients making them more prone to non-uniform carrier density distributions. Moreover, even in semiconductor lasers, where the carrier concentration and the gain are pinned at the onset of lasing to rather pedestrian levels (approximately 1 × 1018 cm-3 and of 3 dB, respectively), previous theoretical analysis for more than a decade postulated that a significant spatial distribution occur. These measurements and analysis

  19. Inherited metabolic diseases affecting the carrier.

    PubMed

    Endres, W

    1997-03-01

    The objective of this review is to draw attention to those inherited metabolic traits which are potentially harmful also for the carrier, and to outline preventive measures, at least for obligate heterozygotes, i.e. parents of homozygous children. Concerning carriers of food-dependent abnormalities, early vascular disease in homocystinuria, hyperammonaemic episodes in ornithine transcarbamylase deficiency, presenile cataracts in galactosaemia as well as galactokinase deficiency, spastic paraparesis in X-linked adrenoleukodystrophy, and HELLP syndrome in mothers of babies with long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency have to be mentioned. In the group of food-independent disorders, clinical features in carriers may be paraesthesias and corneal dystrophy in Fabry disease, lens clouding in Lowe syndrome, lung and/or liver diseases in alpha 1-antitrypsin deficiency, and renal stones in cystinuria type II and III. Finally, two monogenic carrier states are known which in pregnant individuals could possibly afflict the developing fetus, i.e. heterozygosity for galactosaemia and for phenylketonuria. Elevated levels of galactose-1-phosphate have been found in red blood cells of infants heterozygous for galactosaemia born to heterozygous mothers. Aspartame in very high doses is reported to increase blood phenylalanine levels in heterozygotes for phenylketonuria, thus being a risk for the fetus of a heterozygous mother. For some of these carrier states preventive measures can be recommended, e.g. restriction of lactose in parents and heterozygous grandparents of children with galactosaemia and galactokinase deficiency as well as transiently in infants heterozygous for galactosaemia, dietary supplementation with monounsaturated fatty acids in symptomatic carriers for X-linked adrenoleukodystrophy, avoidance of smoking and alcohol in heterozygotes for alpha 1-antitrypsin deficiency, avoidance of episodes of dehydration in heterozygotes for cystinuria, and

  20. Structural characterization of poorly-crystalline scorodite, iron(III)-arsenate co-precipitates and uranium mill neutralized raffinate solids using X-ray absorption fine structure spectroscopy

    SciTech Connect

    Chen, N; Jiang, D T; Cutler, J; Kotzer, T; Jia, Y F; Demopoulos, G P; Rowson, J W

    2009-12-01

    X-ray absorption fine structure (XAFS) is used to characterize the mineralogy of the iron(III)-arsenate(V) precipitates produced during the raffinate (aqueous effluent) neutralization process at the McClean Lake uranium mill in northern Saskatchewan, Canada. To facilitate the structural characterization of the precipitated solids derived from the neutralized raffinate, a set of reference compounds were synthesized and analyzed. The reference compounds include crystalline scorodite, poorly-crystalline scorodite, iron(III)-arsenate co-precipitates obtained under different pH conditions, and arsenate-adsorbed on goethite. The poorly-crystalline scorodite (prepared at pH 4 with Fe/As = 1) has similar As local structure as that of crystalline scorodite. Both As and Fe K-edge XAFS of poorly-crystalline scorodite yield consistent results on As-Fe (or Fe-As) shell. From As K-edge analysis the As-Fe shell has an inter-atomic distance of 3.33 ± 0.02 Å and coordination number of 3.2; while from Fe K-edge analysis the Fe-As distance and coordination number are 3.31 ± 0.02 Å and 3.8, respectively. These are in contrast with the typical arsenate adsorption on bidentate binuclear sites on goethite surfaces, where the As-Fe distance is 3.26 ± 0.03 Å and coordination number is close to 2. A similar local structure identified in the poorly-crystalline scorodite is also found in co-precipitation solids (Fe(III)/As(V) = 3) when precipitated at the same pH (pH = 4): As-Fe distance 3.30 ± 0.03 Å and coordination number 3.9; while at pH = 8 the co-precipitate has As-Fe distance of 3.27 ± 0.03 Å and coordination number about 2, resembling more closely the adsorption case. The As local structure in the two neutralized raffinate solid series (precipitated at pH values up to 7) closely resembles that in the poorly-crystalline scorodite. All of the raffinate solids have the same As-Fe inter-atomic distance as that in the poorly-crystalline scorodite, and a systematic decrease in the

  1. An analytical method for hydrogeochemical surveys: Inductively coupled plasma-atomic emission spectrometry after using enrichment coprecipitation with cobalt and ammonium pyrrolidine dithiocarbamate

    USGS Publications Warehouse

    Hopkins, D.M.

    1991-01-01

    Trace metals that are commonly associated with mineralization were concentrated and separated from natural water by coprecipitation with ammonium pyrollidine dithiocarbamate (APDC) and cobalt and determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The method is useful in hydrogeochemical surveys because it permits preconcentration near the sample sites, and selected metals are preserved shortly after the samples are collected. The procedure is relatively simple: (1) a liter of water is filtered; (2) the pH is adjusted; (3) Co chloride and APDC are added to coprecipitate the trace metals; and (4) later, the precipitate is filtered, dissolved, and diluted to 10 ml for a 100-fold concentration enrichment of the separated metals. Sb(III), As(III), Cd, Cr, Cu, Fe, Pb, Mo, Ni, Ag, V, and Zn can then be determined simultaneously by ICP-AES. In an experiment designed to measure the coprecipitation efficiency, Sb(III), Cd and Ag were recovered at 70 to 75% of their original concentration. The remaining metals were recovered at 85 to 100% of their original concentrations, however. The range for the lower limits of determination for the metals after preconcentration is 0.1 to 3.0 ??g/l. The precision of the method was evaluated by replicate analyses of a Colorado creek water and two simulated water samples. The accuracy of the method was estimated using a water reference standard (SRM 1643a) certified by the U.S. National Bureau of Standards. In addition, the method was evaluated by analyzing groundwater samples collected near a porphyry copper deposit in Arizona and by analyzing meltwater from glacier-covered areas favorable for mineralization in south-central Alaska. The results for the ICP-AES analyses compared favorably with those obtained using the sequential technique of GFAAS on the acidified but unconcentrated water samples. ICP-AES analysis of trace-metal preconcentrates for hydrogeochemical surveys is more efficient than GFAAS because a

  2. Effective Charge Carrier Utilization in Photocatalytic Conversions.

    PubMed

    Zhang, Peng; Wang, Tuo; Chang, Xiaoxia; Gong, Jinlong

    2016-05-17

    Continuous efforts have been devoted to searching for sustainable energy resources to alleviate the upcoming energy crises. Among various types of new energy resources, solar energy has been considered as one of the most promising choices, since it is clean, sustainable, and safe. Moreover, solar energy is the most abundant renewable energy, with a total power of 173 000 terawatts striking Earth continuously. Conversion of solar energy into chemical energy, which could potentially provide continuous and flexible energy supplies, has been investigated extensively. However, the conversion efficiency is still relatively low since complicated physical, electrical, and chemical processes are involved. Therefore, carefully designed photocatalysts with a wide absorption range of solar illumination, a high conductivity for charge carriers, a small number of recombination centers, and fast surface reaction kinetics are required to achieve a high activity. This Account describes our recent efforts to enhance the utilization of charge carriers for semiconductor photocatalysts toward efficient solar-to-chemical energy conversion. During photocatalytic reactions, photogenerated electrons and holes are involved in complex processes to convert solar energy into chemical energy. The initial step is the generation of charge carriers in semiconductor photocatalysts, which could be enhanced by extending the light absorption range. Integration of plasmonic materials and introduction of self-dopants have been proved to be effective methods to improve the light absorption ability of photocatalysts to produce larger amounts of photogenerated charge carriers. Subsequently, the photogenerated electrons and holes migrate to the surface. Therefore, acceleration of the transport process can result in enhanced solar energy conversion efficiency. Different strategies such as morphology control and conductivity improvement have been demonstrated to achieve this goal. Fine-tuning of the

  3. Effective Charge Carrier Utilization in Photocatalytic Conversions.

    PubMed

    Zhang, Peng; Wang, Tuo; Chang, Xiaoxia; Gong, Jinlong

    2016-05-17

    Continuous efforts have been devoted to searching for sustainable energy resources to alleviate the upcoming energy crises. Among various types of new energy resources, solar energy has been considered as one of the most promising choices, since it is clean, sustainable, and safe. Moreover, solar energy is the most abundant renewable energy, with a total power of 173 000 terawatts striking Earth continuously. Conversion of solar energy into chemical energy, which could potentially provide continuous and flexible energy supplies, has been investigated extensively. However, the conversion efficiency is still relatively low since complicated physical, electrical, and chemical processes are involved. Therefore, carefully designed photocatalysts with a wide absorption range of solar illumination, a high conductivity for charge carriers, a small number of recombination centers, and fast surface reaction kinetics are required to achieve a high activity. This Account describes our recent efforts to enhance the utilization of charge carriers for semiconductor photocatalysts toward efficient solar-to-chemical energy conversion. During photocatalytic reactions, photogenerated electrons and holes are involved in complex processes to convert solar energy into chemical energy. The initial step is the generation of charge carriers in semiconductor photocatalysts, which could be enhanced by extending the light absorption range. Integration of plasmonic materials and introduction of self-dopants have been proved to be effective methods to improve the light absorption ability of photocatalysts to produce larger amounts of photogenerated charge carriers. Subsequently, the photogenerated electrons and holes migrate to the surface. Therefore, acceleration of the transport process can result in enhanced solar energy conversion efficiency. Different strategies such as morphology control and conductivity improvement have been demonstrated to achieve this goal. Fine-tuning of the

  4. Flicker noise in hot carrier semiconductors

    SciTech Connect

    Orlov, V.B.; Yakimov, A.V.

    1988-04-01

    Change in electrical flicker noise power in hot carrier semiconductors can be explained by fluctuations in the intensity of impurity scattering, which contradicts the Hooge-Kleinpenning-Vandamme hypothesis, which relates flicker conduction noise to lattice scattering. It has been shown that such noise can be caused by fluctuations in the effective number of neutral scattering centers within the semiconductor volume. This source modulates carrier mobility, i.e., mobility fluctuations are a secondary effect. We offer herein an explanation of known experimental data on 1/f noise in silicon and gallium arsenide.

  5. CONCENTRATION OF Pu USING OXALATE TYPE CARRIER

    DOEpatents

    Ritter, D.M.; Black, R.P.S.

    1960-04-19

    A method is given for dissolving and reprecipitating an oxalate carrier precipitate in a carrier precipitation process for separating and recovering plutonium from an aqueous solution. Uranous oxalate, together with plutonium being carried thereby, is dissolved in an aqueous alkaline solution. Suitable alkaline reagents are the carbonates and oxulates of the alkali metals and ammonium. An oxidizing agent selected from hydroxylamine and hydrogen peroxide is then added to the alkaline solution, thereby oxidizing uranium to the hexavalent state. The resulting solution is then acidified and a source of uranous ions provided in the acidified solution, thereby forming a second plutoniumcarrying uranous oxalate precipitate.

  6. BISMUTH PHOSPHATE CARRIER PROCESS FOR Pu RECOVERY

    DOEpatents

    Finzel, T.G.

    1959-02-01

    An improvement in the bismuth phosphate carrier precipitation process for recovering plutonium is described. It has been found that a more granular and more easily filterable carrier precipitiite is formed if the addition of the bismuth and phosphate ions is effected by first adding 9/10 of the bismuth ions necessary, then slowly adding all of the source of the phosphate ions to be incorporated in the precipitate, while digesting at 75 C and afterwards incorporating the remainder of the total bismuth ions necessary

  7. Extracellular stability of nanoparticulate drug carriers

    PubMed Central

    Liu, Karen C.; Yeo, Yoon

    2014-01-01

    Nanoparticulate (NP) drug carrier systems are attractive vehicles for selective drug delivery to solid tumors. Ideally, NPs should evade clearance by the reticuloendothelial system while maintaining the ability to interact with tumor cells and facilitate cellular uptake. Great effort has been made to fulfill these design criteria, yielding various types of functionalized NPs. Another important consideration in NP design is the physical and functional stability during circulation, which, if ignored, can significantly undermine the promise of intelligently designed NP drug carriers. This commentary reviews several NP examples with stability issues and their consequences, ending in a discussion of experimental methods for reliable prediction of NP stability. PMID:24214175

  8. Advanced two-way satellite frequency transfer by carrier-phase and carrier-frequency measurements

    NASA Astrophysics Data System (ADS)

    Fujieda, Miho; Gotoh, Tadahiro; Amagai, Jun

    2016-06-01

    Carrier-phase measurement is one of the ways to improve the measurement resolution of two-way satellite frequency transfer. We introduce two possible methods for carrier-phase measurement: direct carrier-phase detection identified by Two-Way Carrier-Phase (TWCP) and the use of carrier-frequency information identified by Two-Way Carrier Frequency (TWCF). We performed the former using an arbitrary waveform generator and an analog-to-digital sampler and the latter using a conventional modem. The TWCF measurement using the modem had a resolution of 10-13 and the result agreed with that obtained by GPS carrier-phase frequency transfer in a 1500 km baseline. The measurement accuracy may have been limited by the poor frequency resolution of the modem; however, the TWCF measurement was able to improve the stability of conventional two-way satellite frequency transfer. Additionally, we show that the TWCP measurement system has the potential to achieve a frequency stability of 10-17.

  9. Structural and magnetic properties of nano-sized NiCuZn ferrites synthesized by co-precipitation method with ultrasound irradiation

    NASA Astrophysics Data System (ADS)

    Harzali, Hassen; Saida, Fairouz; Marzouki, Arij; Megriche, Adel; Baillon, Fabien; Espitalier, Fabienne; Mgaidi, Arbi

    2016-12-01

    Sonochemically assisted co-precipitation has been used to prepare nano-sized Ni-Cu-Zn-ferrite powders. A suspension of constituent hydroxides was ultrasonically irradiated for various times at different temperatures with high intensity ultrasound radiation using a direct immersion titanium horn. Structural and magnetic properties were investigated using X-diffraction (XRD), FT-IR spectroscopy, transmission electron microscopy (TEM), Nitrogen adsorption at 77 K (BET) and Vibrating sample magnetometer (VSM). Preliminary experimental results relative to optimal parameters showed that reaction time t=2 h, temperature θ=90 °C and dissipated Power Pdiss=46.27 W. At these conditions, this work shows the formation of nanocrystalline single-phase structure with particle size 10-25 nm. Also, ours magnetic measurements proved that the sonochemistry method has a great influence on enhancing the magnetic properties of the ferrite.

  10. Superacid Catalyst SO42-/ZrO2-La2O3 Prepared by Ultrasonic Co-precipitation and Low Temperature Aging

    NASA Astrophysics Data System (ADS)

    Chen, Tong-yun; Chu, Xiang-feng; Hu, Ke-liang

    2009-06-01

    Sulfated zirconia-lanthana (SO42-/ZrO2-La2O3) precursors were prepared by ultrasonic coprecipitation method and followed by aging at different temperature. The precursors were treated by 0.5 mol/L H2SO4. Samples of SO42-/ZrO2-La2O3 nano-crystalline catalysts were obtained by baking the treated precursors at different temperatures. The acidic properties of SO42-/ZrO2-La2O3 were tested by the Hammett indicator method. The phase composition, specific area, particle structure, and surface state were characterized by X-ray diffraction, BET, transmission electron microscopy, infrared spectrum, and X-ray photoelectron spectroscopy. The catalytic activities were estimated by esterification of acetic acid with glycerin. It was shown that the catalyst prepared by ultrasonic stirring and low temperature (-15°C) exhibited highly active sites and high catalytic property.

  11. Preparation and characterization of hollow glass microspheres coated by CoFe{sub 2}O{sub 4} nanoparticles using urea as precipitator via coprecipitation method

    SciTech Connect

    Pang Xiaofen; Fu Wuyou; Yang Haibin Zhu Hongyang; Xu Jing; Li Xiang; Zou Guangtian

    2009-02-04

    The composite of hollow glass microspheres coated by CoFe{sub 2}O{sub 4} nanoparticles has been successfully prepared using urea as precipitator via coprecipitation method. The resultant composites were characterized by X-ray diffraction, field emission scanning electron microscope and vibrating sample magnetometer. The results showed that the slow decomposition of urea could be beneficial to form uniform and entire cobalt ferrite coating layer on the surface of hollow glass microspheres. The smoothest morphology was obtained for the sample prepared from 0.7 M urea, while the sample prepared from 1.0 M urea had the thickest shell. This indicated that there was a competition between the morphology and thickness of the coated microspheres. A possible formation mechanism of hollow glass microspheres coated with cobalt ferrite was proposed. The magnetic properties of the samples were also investigated.

  12. Synthesis and characterization of polyethylene glycol (PEG) coated Fe3O4 nanoparticles by chemical co-precipitation method for biomedical applications.

    PubMed

    Anbarasu, M; Anandan, M; Chinnasamy, E; Gopinath, V; Balamurugan, K

    2015-01-25

    Polyethylene glycol (PEG) coated Fe3O4 nanoparticles were synthesized by chemical co-precipitation method. With polyethylene glycol (PEG) as a stabilizer and dispersant. The X-ray diffraction and selected area electron diffraction (SAED) results show that the cubic inverse spinel structure of pure phase polycrystalline Fe3O4 was obtained. The scanning electron microscopy (SEM) and field emission transmission electron microscopy (FE-TEM) results exhibited that the resulted Fe3O4 nanoparticles were roughly spherical in shape with narrow size distribution and homogenous shape. Fourier transform infrared spectroscopy (FT-IR) results suggested that PEG indicated with Fe3O4 via its carbonyl groups. Results of vibrating sample magnetometer (VSM) indicated that the prepared Fe3O4 nanoparticles exhibit superparamagnetic behavior and high saturation magnetization at room temperature. Such Fe3O4 nanoparticles with favorable size and tunable magnetic properties are promising biomedical applications.

  13. Synthesis and characterization of polyethylene glycol (PEG) coated Fe3O4 nanoparticles by chemical co-precipitation method for biomedical applications

    NASA Astrophysics Data System (ADS)

    Anbarasu, M.; Anandan, M.; Chinnasamy, E.; Gopinath, V.; Balamurugan, K.

    2015-01-01

    Polyethylene glycol (PEG) coated Fe3O4 nanoparticles were synthesized by chemical co-precipitation method. With polyethylene glycol (PEG) as a stabilizer and dispersant. The X-ray diffraction and selected area electron diffraction (SAED) results show that the cubic inverse spinel structure of pure phase polycrystalline Fe3O4 was obtained. The scanning electron microscopy (SEM) and field emission transmission electron microscopy (FE-TEM) results exhibited that the resulted Fe3O4 nanoparticles were roughly spherical in shape with narrow size distribution and homogenous shape. Fourier transform infrared spectroscopy (FT-IR) results suggested that PEG indicated with Fe3O4 via its carbonyl groups. Results of vibrating sample magnetometer (VSM) indicated that the prepared Fe3O4 nanoparticles exhibit superparamagnetic behavior and high saturation magnetization at room temperature. Such Fe3O4 nanoparticles with favorable size and tunable magnetic properties are promising biomedical applications.

  14. Photocatalytic properties of BiVO{sub 4} prepared by the co-precipitation method: Degradation of rhodamine B and possible reaction mechanisms under visible irradiation

    SciTech Connect

    Martinez-de la Cruz, A.; Perez, U.M. Garcia

    2010-02-15

    Bismuth vanadate (BiVO{sub 4}) was synthesized by the co-precipitation method at 200 {sup o}C. The photocatalytic activity of the oxide was tested for the photodegradation of rhodamine B under visible light irradiation. The analysis of the total organic carbon showed that the mineralization of rhodamine B over a BiVO{sub 4} photocatalyst ({approx}40% after 100 h of irradiation) is feasible. In the same way, a gas chromatography analysis coupled with mass spectroscopy revealed the existence of organic intermediates during the photodegradation process such as ethylbenzene, o-xylene, m-xylene, and phthalic anhydride. The modification of variables such as dispersion pH, amount of dissolved O{sub 2}, and irradiation source was studied in order to know the details about the photodegradation mechanism.

  15. Effect of pH variation on the stability and structural properties of In(OH)3 nanoparticles synthesized by co-precipitation method

    NASA Astrophysics Data System (ADS)

    Goh, Kian Wei; Johan, Mohd Rafie; Wong, Yew Hoong

    2016-10-01

    Indium hydroxide (In(OH)3) nanoparticles were synthesized at various pH values (8-11) by co-precipitation method. Its properties were characterized by X-ray diffractometer, Fourier transform infrared spectroscopy, Raman spectroscopy and transmission electron microscope. The electrostatic stability of nanoparticles is carried out through zeta potential measurement. The crystallite size of nanoparticles calculated by Scherrer equation has similar trend with the values obtained from William-Hall plot. TEM images show that the particles size is within the range of 11.76-20.76 nm. The maximum zeta potential is 3.68 mV associated with the smallest particle size distribution of 92.6 nm occurred at pH 10. Our work clearly confirms the crystallite size, stability and the morphology of In(OH)3 NPs are strongly depending on the pH of precursor solution.

  16. Fabrication of Far Red Emission Phosphors Y3Al5O12:Eu(YAG:Eu) by Co-precipitation Method

    NASA Astrophysics Data System (ADS)

    Thu, L. D.; Trung, D. Q.; Lam, T. D.; Anh, T. X.

    2016-05-01

    Phosphors YAG:Eu (with seven molar percent of Eu to YAG) was synthesized by the co-precipitation method using NH3 solution as a precipitating agent. X-ray diffraction (XRD) patterns show that the samples are single phase, and the crystallinity starts forming at a sintering temperature of 1000°C. The crystallinity increases with the increasing sintered temperature. XRD studies followed by Rietveld refinement confirmed the body center cubic structure of the host lattice. The crystalline YAG:Eu showed four emission bands of europium ion with the force dipole transition ascribed to 5D0-7F4 located at 710 nm as the most dominating group (far-red emission—FR). The ratio of FR/OR (far-red/orange—red) is about 1.24 in all samples.

  17. Compactibility and sintering behavior of nanocrystalline (Th 1-xCe x)O 2 powders synthesized by co-precipitation process

    NASA Astrophysics Data System (ADS)

    Yildiz, Ö.; Modolo, G.; Telle, R.

    2008-07-01

    Thoria (ThO2) based ceramic material is a versatile and very important matrix for immobilization of plutonium and other tetravalent actinides either as a burning or a deposition material for final disposal. The aim of this study was to investigate the influence of the actinide concentration (simulated with cerium), the fabrication conditions and the properties of the produced powders on the compactibility and sinterability of the final products. The (Th1-xCex)O2 powders with ceria concentration varying from 5 to 50 mol% were synthesized by co-precipitation method. The pellets were then compacted from calcined and ground powders at pressures varying from 250 to 750 MPa. The produced pellets had a homogenous grain size and sintered densities of 0.88% to 0.95% TD, respectively.

  18. Magnetic and dielectric characterization of Co0.9Ni0.1Fe2O4 prepared by hydroxide co-precipitation method

    NASA Astrophysics Data System (ADS)

    Mane, S. M.; Tirmali, P. M.; Kolekar, C. B.; Kulkarni, S. B.

    2016-04-01

    Co1-x NixFe2O4 (where x=0.1) were prepared by using the hydroxide co-precipitation method. An obtained precipitate was sintered at 1100°C by microwave sintering technique. The structural analysis confirms the single-phase cubic spinel structure with Fd-3m space group. The magnetic characterization was carried out at temperature 300K.Saturation magnetisation and coercivity is 77.22 and 908 Oe. Irreversibility is observed between the ZFC and FC curves at 100 Oe. The variation in the dielectric constant and loss tangent are studied at room temperature with increasing frequency. Continues decrease in the the dielectric constant with increasing frequency shows inverse dependence on frequency. Morphological and elemental studies were done by using the scanning electron microscope with EDAX.

  19. Comparison of structural and electrical properties of Co{sup 2+}doped Mn-Zn soft nano ferrites prepared via coprecipitation and hydrothermal methods

    SciTech Connect

    Anwar, Humaira; Maqsood, Asghari

    2014-01-01

    Graphical abstract: - Highlights: • Coprecipitation and hydrothermal synthesis of Co{sup 2+} doped Mn-Zn ferrites. • Dielectric measurements at 3 MHz and 1 GHz frequencies. • Enhanced DC electrical resistivity for samples prepared from hydrothermal technique. • Impedance studies for the prepared samples showing major contribution due to grains. - Abstract: A series of Co doped Mn-Zn ferrites compounds with the formula Mn{sub 0.5}Zn{sub 0.5−x}Co{sub x}Fe{sub 2}O{sub 4} (x = 0, 0.15, 0.25, 0.35 and 0.50) were successfully synthesized by polyethylene glycol-assisted coprecipitation and hydrothermal methods. The structural characterization of the samples was done using X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR). All the samples found to have cubic spinel structure. The average crystallite size of all nanoparticles were estimated using Scherrer's formula and found to lie between 10 and 25 ± 3 nm with small size distribution of particles prepared by hydrothermal method. The FTIR spectrum showed two absorption bands of tetrahedral and octahedral metal-oxygen sites. DC electrical resistivity varied from 4.12 × 10{sup 7} to 8.32 × 10{sup 10} ohm cm with cobalt doping. The dielectric measurements were performed from 20 Hz to 3 MHz and from 1 MHz to 1 GHz frequency ranges. The value of dielectric constant (ε′) varies from 15.54 to 106.25 (1 MHz) and 6.73–16.48 (1 GHz) for all the samples at room temperature. Impedance spectroscopy was carried out from 20 Hz to 3 MHz, at room temperature to study the grains and grain boundaries effect.

  20. The effect of microbial sulfidogenesis on the stability of As-Fe coprecipitate with low Fe/As molar ratio under anaerobic conditions.

    PubMed

    Wang, Shaofeng; He, Xin Yu; Pan, Rongrong; Xu, Liying; Wang, Xin; Jia, Yongfeng

    2016-04-01

    The effect of microbial sulfidogenesis on As transformation and mobilization in solid phase with low Fe/As ratio is still not well known. In this study, microbial transformation and mobilization of As in the As-Fe coprecipitate with different sulfate levels were investigated using chemical extraction and K-edge XANES of As and S. Results showed that approximately 2.7, 24.4, and 83.7 % of total As were released into the aqueous phase in the low-, mid-, and high-sulfate treatments, respectively, indicating that the presence of large amounts of sulfate could enhance microbial arsenic mobilization in the As-Fe coprecipitate. In the low-sulfate treatment, As mobilization was primarily attributed to the reductive dissolution of the Fe (oxy)hydroxides and the As reduction and desorption. In the mid- and high-sulfate treatments, the reduction of arsenate and ferric iron was significantly enhanced. Complete ferric iron reduction was observed in the solid phase, implying that Fe (oxy)hydroxide was transformed to secondary minerals and may be the one of the primary causes for the enhanced As mobilization. Thermodynamic calculations predicted the formation of thioarsenite species after 35 days of incubation based on the concentration of dissolved As(III) and S(-II). Since thioarsenic species is more mobile, its formation may be one of the most important factors enhancing the As release in the high-sulfate system. The result of this study is of significance to completely predict the environmental behavior of As associated with Fe (hydr)oxides in the presence of microbial sulfidogenesis under anoxic conditions. PMID:26676545

  1. XRD line-broadening characteristics of M-oxides (M = Mg, Mg-Al, Y, Fe) nanoparticles produced by coprecipitation method

    SciTech Connect

    Pratapa, S.; Susanti, L.; Insany, Y. A. S.; Alfiati, Z.; Hartono, B.; Mashuri,; Triwikantoro; Baqiya, M. A.; Purwaningsih, S.; Yahya, E.; Darminto; Taufiq, Ahmad; Fuad, Abdullah

    2010-10-24

    Simple coprecipitation method has been used to produce nanoparticles of MgO (magnesia), MgO{center_dot}Al{sub 2}O{sub 3}(spinel), Y{sub 2}O{sub 3}(yttria) and Fe{sub 3}O{sub 4}(ferrite). The raw materials were, in respective, magnesium powder, magnesium and aluminium powders, ytrria powder, and natural sand. The coprecipitation included the use of suitable acid and base to dissolve the powders or sand and to produce precipitates, as well as the use of water to wash and purify the precipitates, and drying at relatively low temperatures, namely lower than 100 deg. C, followed by heating at 450 deg. C, 750 deg. C, 600 deg. C and 200 deg. C to produce magnesia, spinel, yttria and ferrite nanopowders, respectively. X-ray diffractometry was used to characterise the purity and nanocrystallinity of the final powders. It was found qualitatively that the powders were of high purity. Further line-broadening analysis using single-line and Rietveld-based softwares was performed to reveal the nanocrystallinity of the powders. Different line breadth values were found for the powders, indicating different crystallite sizes. It was also found that, particularly for spinel and yttria, the diffraction peaks exhibited 'longer' tails, indicating broader crystallite size distribution. The average crystallite size for the powders ranged from 3 to 70 nm. The results could then be used as 'fingerprints' for nanocrystallinity using x-ray diffractometry. The XRD crystallite sizes for yttria and ferrite nanocrystals are in fair agreement with their counterparts from electron microscopy observation.

  2. Managing photons and carriers for photocatalysis

    NASA Astrophysics Data System (ADS)

    Thomann, Isabell; Robatjazi, Hossein; Bahauddin, Shah; Doiron, Chloe; Liu, Xuejun; Tumkur, Thejaswi; Wang, Wei-Ren; Wray, Parker

    While small plasmonic nanoparticles efficiently generate energetic hot carriers, light absorption in a monolayer of such particles is inefficient, and practical utilization of the hot carriers in addition requires efficient charge-separation. Here we describe our approach to address both challenges. By designing an optical cavity structure for the plasmonic photoelectrode, light absorption in these particles can be significantly enhanced, resulting in efficient hot electron generation. Rather than utilizing a Schottky barrier to preserve the energy of the carriers, our structure allows for their direct injection into the adjacent electrolyte. On the substrate side, the plasmonic particles are in contact with a wide band gap oxide film that serves as an electron blocking layer but accepts holes and transfers them to the counter electrode. The observed photocurrent spectra follow the plasmon spectrum, and demonstrate that the extracted electrons are energetic enough to drive the hydrogen evolution reaction. A similar structure can be designed to achieve broadband absorption enhancement in monolayer MoS2. Time permitting, I will discuss charge carrier dynamics in hybrid nanoparticles composed of plasmonic / two-dimensional materials, and applications of photo-induced force microscopy to study photocatalytic processes.

  3. Itaconic acid carrier ampholytes for isoelectric focusing.

    PubMed

    Brenna, O

    1977-04-11

    Commercial carrier ampholytes, obtained by coupling polyethylene polyamines to acrylic acid, exhibit a conductivity minimum in the pH range 5.5-6.5 owing to the lack of appropriate pK values of the polyamine in this pH region. By replacing acrylic with itaconic acid, it has been possible to effect substantial improvements in the pH range 5.5-6.5 as itaconic acid has a pK2 value of 5.45. Upon coupling, the pK of the gramma-carboxyl group remains virtually unaltered. With itoconic acid carrier ampholytes it has been possible to improve the conductivity in the pH range 5.5-6.5 by as much as 400% compared with conventional carrier ampholytes. It is suggected that the commercial products should be supplemented with itaconic acid carrier ampholytes in order to obtain a more uniform conductivity and buffering capacity in the pH range 3-10.

  4. 14 CFR 221.2 - Carrier's duty.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... of Property; (3) Part 297, Foreign Air Freight Forwarders and Foreign Cooperative Shippers... Trips by Foreign Air Carriers; (9) Part 292, International Cargo Transportation, except as provided in part 292. (10) Part 293 International Passenger Transportation, except as provided in part 293....

  5. 14 CFR 221.2 - Carrier's duty.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... of Property; (3) Part 297, Foreign Air Freight Forwarders and Foreign Cooperative Shippers... Trips by Foreign Air Carriers; (9) Part 292, International Cargo Transportation, except as provided in part 292. (10) Part 293 International Passenger Transportation, except as provided in part 293....

  6. 14 CFR 221.2 - Carrier's duty.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... of Property; (3) Part 297, Foreign Air Freight Forwarders and Foreign Cooperative Shippers... Trips by Foreign Air Carriers; (9) Part 292, International Cargo Transportation, except as provided in part 292. (10) Part 293 International Passenger Transportation, except as provided in part 293....

  7. 42 CFR 421.200 - Carrier functions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Carrier functions. 421.200 Section 421.200 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... a channel of communication to and from CMS of information, instructions, and other material...

  8. Carrier recovery techniques on satellite mobile channels

    NASA Technical Reports Server (NTRS)

    Vucetic, B.; Du, J.

    1990-01-01

    An analytical method and a stored channel model were used to evaluate error performance of uncoded quadrature phase shift keying (QPSK) and M-ary phase shift keying (MPSK) trellis coded modulation (TCM) over shadowed satellite mobile channels in the presence of phase jitter for various carrier recovery techniques.

  9. 7 CFR 35.4 - Carrier.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Carrier. 35.4 Section 35.4 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS EXPORT...

  10. 7 CFR 35.4 - Carrier.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Carrier. 35.4 Section 35.4 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS EXPORT...

  11. Solid state cloaking for electrical charge carrier mobility control

    DOEpatents

    Zebarjadi, Mona; Liao, Bolin; Esfarjani, Keivan; Chen, Gang

    2015-07-07

    An electrical mobility-controlled material includes a solid state host material having a controllable Fermi energy level and electrical charge carriers with a charge carrier mobility. At least one Fermi level energy at which a peak in charge carrier mobility is to occur is prespecified for the host material. A plurality of particles are distributed in the host material, with at least one particle disposed with an effective mass and a radius that minimize scattering of the electrical charge carriers for the at least one prespecified Fermi level energy of peak charge carrier mobility. The minimized scattering of electrical charge carriers produces the peak charge carrier mobility only at the at least one prespecified Fermi level energy, set by the particle effective mass and radius, the charge carrier mobility being less than the peak charge carrier mobility at Fermi level energies other than the at least one prespecified Fermi level energy.

  12. Prenatal Carrier Screening for Spinal Muscular Atrophy.

    PubMed

    Wood, S Lindsay; Brewer, Fallon; Ellison, Rebecca; Biggio, Joseph R; Edwards, Rodney K

    2016-10-01

    Introduction Spinal muscular atrophy (SMA), a neurodegenerative genetic disorder, affects 1:5,000 to 1:10,000 infants. Carrier rates are 1:25 to 1:50. We implemented ACOG-endorsed prenatal SMA screening in mid-2014 and sought to assess uptake, observed carrier rate, and providers' knowledge and attitudes toward genetic conditions and carrier screening. Methods Retrospective cohort study of all patients receiving prenatal genetic counseling at our institution from August 2014 to April 2015. Factors associated with screening uptake were assessed. Proportions who accepted screening, were screen-positive, had partners tested, had partners who were screen-positive, and had fetuses tested were calculated. Providers' knowledge and attitudes were assessed using a validated questionnaire. Results Of 1,158 patients offered SMA screening, 224 accepted (19.3%, 95% CI 17.2-21.7). Uptake differed by race, parity, religion, and genetic counselor seen. Five (2.2% or 1:45, 95% CI 0.8-5.3 or 1:19-1:125) women were identified as carriers. Of 3 partners screened, none screened positive (0%, 95% CI 0-5.3). There were no prenatal SMA diagnoses (0%, 95% CI 0-1.4). Of 90 survey respondents, 42% incorrectly answered 1 of 9 knowledge questions. Provider attitudes toward screening were contradictory. Conclusion Despite significant resources utilized, prenatal SMA carrier screening identified no fetal cases. Cost-effectiveness and other barriers should be considered prior to large-scale adoption of more comprehensive genetic screening. PMID:27611803

  13. Radiative recombination of hot carriers in narrow-gap semiconductors

    SciTech Connect

    Pavlov, N. V.; Zegrya, G. G.

    2012-01-15

    The mechanism of the radiative recombination of hot carriers in narrow-gap semiconductors is analyzed using the example of indium antimonide. It is shown that the CHCC Auger recombination process may lead to pronounced carrier heating at high excitation levels. The distribution functions and concentrations of hot carriers are determined. The radiative recombination rate of hot carriers and the radiation gain coefficient are calculated in terms of the Kane model. It is demonstrated that the radiative recombination of hot carriers will make a substantial contribution to the total radiative recombination rate at high carrier concentrations.

  14. Lower frequency of Gaucher disease carriers among Tay-Sachs disease carriers.

    PubMed

    Peleg, L; Frisch, A; Goldman, B; Karpaty, M; Narinsky, R; Bronstein, S; Frydman, M

    1998-01-01

    The heterozygote frequency of Gaucher disease (GD) and Tay-Sachs disease (TSD) is distinctly high among Ashkenazi Jews (1:29 for TSD and 1:16 for GD). Two main theories have been suggested to explain this high occurrence: a founder effect with subsequent genetic drift, and a selective advantage of heterozygotes. We compared the frequency of the GD most common mutation (1226A-->G) among carriers of the common TSD mutation (+1277 TATC) with the frequency of this mutation in the general Ashkenazi population. The frequency of GD carriers among 308 TSD heterozygotes was 1:28 which is about half the expected (P = 0.03). These results indicate that carriers of both diseases do not possess additional evolutionary advantage over single mutation carriers. A reasonable interpretation of these findings is that one or both mutations have arisen relatively recently in different regions of Europe and have not yet reached genetic equilibrium. PMID:9781065

  15. Modeling Minority-Carrier Lifetime Techniques That Use Transient Excess-Carrier Decay: Preprint

    SciTech Connect

    Johnston, S. W.; Berman, G. M.; Ahrenkiel, R. K.

    2008-05-01

    Lifetime spectroscopy is a valuable tool for the characterization of PV materials. This paper combines modeling and experimental results to illustrate the injection-level dependent response of three transient excess-carrier decay techniques.

  16. LWS/SET Technology Experiment Carrier

    NASA Technical Reports Server (NTRS)

    Sherman, Barry; Giffin, Geoff

    2002-01-01

    This paper examines the approach taken to building a low-cost, modular spacecraft bus that can be used to support a variety of technology experiments in different space environments. It describes the techniques used and design drivers considered to ensure experiment independence from as yet selected host spacecraft. It describes the technology experiment carriers that will support NASA's Living With a Star Space Environment Testbed space missions. NASA has initiated the Living With a Star (LWS) Program to develop a better scientific understanding to address the aspects of the connected Sun-Earth system that affect life and society. A principal goal of the program is to bridge the gap between science, engineering, and user application communities. The Space Environment Testbed (SET) Project is one element of LWS. The Project will enable future science, operational, and commercial objectives in space and atmospheric environments by improving engineering approaches to the accommodation and/or mitigation of the effects of solar variability on technological systems. The SET Project is highly budget constrained and must seek to take advantage of as yet undetermined partnering opportunities for access to space. SET will conduct technology validation experiments hosted on available flight opportunities. The SET Testbeds will be developed in a manner that minimizes the requirements for accommodation, and will be flown as flight opportunities become available. To access the widest range of flight opportunities, two key development requirements are to maintain flexibility with respect to accommodation constraints and to have the capability to respond quickly to flight opportunities. Experiments, already developed to the technology readiness level of needing flight validation in the variable Sun-Earth environment, will be selected on the basis of the need for the subject technology, readiness for flight, need for flight resources and particular orbit. Experiments will be

  17. Lattice-Matched Hot Carrier Solar Cell with Energy Selectivity Integrated into Hot Carrier Absorber

    NASA Astrophysics Data System (ADS)

    König, Dirk; Takeda, Yasuhiko; Puthen-Veettil, Binesh; Conibeer, Gavin

    2012-10-01

    We propose a technologically feasible concept of a hot carrier (HC) solar cell (SC) which fulfills the electronic, optical, and to some extent the phononic criteria required. The energy selective process of HCs is implemented into the hot carrier absorber (HCA). Its electronic properties are investigated by a Monte-Carlo code which simulates random deviations of structure thickness and a normal distribution of random elastic electron (e-) scattering. The structure can be grown epitaxially as a HC-SC test device.

  18. Carrier-interleaved orthogonal multi-electrode multi-carrier resistivity-measurement tool

    NASA Astrophysics Data System (ADS)

    Cai, Yu; Sha, Shuang

    2016-09-01

    This paper proposes a new carrier-interleaved orthogonal multi-electrode multi-carrier resistivity-measurement tool used in a cylindrical borehole environment during oil-based mud drilling processes. The new tool is an orthogonal frequency division multiplexing access-based contactless multi-measurand detection tool. The tool can measure formation resistivity in different azimuthal angles and elevational depths. It can measure many more measurands simultaneously in a specified bandwidth than the legacy frequency division multiplexing multi-measurand tool without a channel-select filter while avoiding inter-carrier interference. The paper also shows that formation resistivity is not sensitive to frequency in certain frequency bands. The average resistivity collected from N subcarriers can increase the measurement of the signal-to-noise ratio (SNR) by N times given no amplitude clipping in the current-injection electrode. If the clipping limit is taken into account, with the phase rotation of each single carrier, the amplitude peak-to-average ratio can be reduced by 3 times, and the SNR can achieve a 9/N times gain over the single-carrier system. The carrier-interleaving technique is also introduced to counter the carrier frequency offset (CFO) effect, where the CFO will cause inter-pad interference. A qualitative analysis and simulations demonstrate that block-interleaving performs better than tone-interleaving when coping with a large CFO. The theoretical analysis also suggests that increasing the subcarrier number can increase the measurement speed or enhance elevational resolution without sacrificing receiver performance. The complex orthogonal multi-pad multi-carrier resistivity logging tool, in which all subcarriers are complex signals, can provide a larger available subcarrier pool than other types of transceivers.

  19. Thermal-drag carrier cooling in undoped semiconductors

    NASA Astrophysics Data System (ADS)

    Huang, Danhong; Apostolova, T.; Alsing, P. M.; Cardimona, D. A.

    2005-09-01

    An approach for carrier cooling in undoped and contactless semiconductors is proposed by using thermal-drag effects in comparison with other methods, such as direct resonant tunneling, nonresonant thermionic, and junction-tunneling cooling, as well as indirect optothermionic and thermoelectric cooling, of carriers in doped and contacted semiconductors. A four-step microscopic model is proposed for this thermal-drag carrier cooling in undoped semiconductors. Wide-band-gap semiconductors with small lattice specific heat and small exchange specific heat between carriers and phonons are found to achieve the best thermal-drag carrier cooling under near-band-edge interband pumping by a weak field. This indirect carrier cooling is accompanied by the lattice cooling. The carrier temperature is pinned to the lattice temperature due to ultrafast carrier-phonon scattering, and it is dragged down by the reduction of the lattice temperature, i.e., the thermal-drag effects.

  20. 47 CFR 54.405 - Carrier obligation to offer Lifeline.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... (CONTINUED) UNIVERSAL SERVICE Universal Service Support for Low-Income Consumers § 54.405 Carrier obligation... demonstrate continued eligibility within the 60-day time period. A carrier providing Lifeline service in...

  1. 47 CFR 54.405 - Carrier obligation to offer Lifeline.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... (CONTINUED) UNIVERSAL SERVICE Universal Service Support for Low-Income Consumers § 54.405 Carrier obligation... within the 60-day time period. A carrier providing Lifeline service in a state that has...

  2. Experimental distribution of entanglement with separable carriers.

    PubMed

    Fedrizzi, A; Zuppardo, M; Gillett, G G; Broome, M A; Almeida, M P; Paternostro, M; White, A G; Paterek, T

    2013-12-01

    The key requirement for quantum networking is the distribution of entanglement between nodes. Surprisingly, entanglement can be generated across a network without direct transfer-or communication-of entanglement. In contrast to information gain, which cannot exceed the communicated information, the entanglement gain is bounded by the communicated quantum discord, a more general measure of quantum correlation that includes but is not limited to entanglement. Here, we experimentally entangle two communicating parties sharing three initially separable photonic qubits by exchange of a carrier photon that is unentangled with either party at all times. We show that distributing entanglement with separable carriers is resilient to noise and in some cases becomes the only way of distributing entanglement through noisy environments.

  3. Superconductivity in carrier-doped silicon carbide

    NASA Astrophysics Data System (ADS)

    Muranaka, Takahiro; Kikuchi, Yoshitake; Yoshizawa, Taku; Shirakawa, Naoki; Akimitsu, Jun

    2008-12-01

    We report growth and characterization of heavily boron-doped 3C-SiC and 6H-SiC and Al-doped 3C-SiC. Both 3C-SiC:B and 6H-SiC:B reveal type-I superconductivity with a critical temperature Tc=1.5 K. On the other hand, Al-doped 3C-SiC (3C-SiC:Al) shows type-II superconductivity with Tc=1.4 K. Both SiC:Al and SiC:B exhibit zero resistivity and diamagnetic susceptibility below Tc with effective hole-carrier concentration n higher than 1020 cm-3. We interpret the different superconducting behavior in carrier-doped p-type semiconductors SiC:Al, SiC:B, Si:B and C:B in terms of the different ionization energies of their acceptors.

  4. Carrier Modulation Via Waveform Probability Density Function

    NASA Technical Reports Server (NTRS)

    Williams, Glenn L.

    2004-01-01

    Beyond the classic modes of carrier modulation by varying amplitude (AM), phase (PM), or frequency (FM), we extend the modulation domain of an analog carrier signal to include a class of general modulations which are distinguished by their probability density function histogram. Separate waveform states are easily created by varying the pdf of the transmitted waveform. Individual waveform states are assignable as proxies for digital ONEs or ZEROs. At the receiver, these states are easily detected by accumulating sampled waveform statistics and performing periodic pattern matching, correlation, or statistical filtering. No fundamental natural laws are broken in the detection process. We show how a typical modulation scheme would work in the digital domain and suggest how to build an analog version. We propose that clever variations of the modulating waveform (and thus the histogram) can provide simple steganographic encoding.

  5. Radionuclide carriers for targeting of cancer

    PubMed Central

    Sofou, Stavroula

    2008-01-01

    This review describes strategies for the delivery of therapeutic radionuclides to tumor sites. Therapeutic approaches are summarized in terms of tumor location in the body, and tumor morphology. These determine the radionuclides of choice for suggested targeting ligands, and the type of delivery carriers. This review is not exhaustive in examples of radionuclide carriers for targeted cancer therapy. Our purpose is two-fold: to give an integrated picture of the general strategies and molecular constructs currently explored for the delivery of therapeutic radionuclides, and to identify challenges that need to be addressed. Internal radiotherapies for targeting of cancer are at a very exciting and creative stage. It is expected that the current emphasis on multidisciplinary approaches for exploring such therapeutic directions should enable internal radiotherapy to reach its full potential. PMID:18686778

  6. Carrier heating and negative photoconductivity in graphene

    SciTech Connect

    Heyman, J. N.; Stein, J. D.; Kaminski, Z. S.; Banman, A. R.; Massari, A. M.; Robinson, J. T.

    2015-01-07

    We investigated negative photoconductivity in graphene using ultrafast terahertz techniques. Infrared transmission was used to determine the Fermi energy, carrier density, and mobility of p-type chemical vapor deposition graphene samples. Time-resolved terahertz photoconductivity measurements using a tunable mid-infrared pump probed these samples at photon energies between 0.35 eV and 1.55 eV, approximately one-half to three times the Fermi energy of the samples. Although interband optical transitions in graphene are blocked for pump photon energies less than twice the Fermi energy, we observe negative photoconductivity at all pump photon energies investigated, indicating that interband excitation is not required to observe this effect. Our results are consistent with a thermalized free-carrier population that cools by electron-phonon scattering, but are inconsistent with models of negative photoconductivity based on population inversion.

  7. Chemical Looping Technology: Oxygen Carrier Characteristics.

    PubMed

    Luo, Siwei; Zeng, Liang; Fan, Liang-Shih

    2015-01-01

    Chemical looping processes are characterized as promising carbonaceous fuel conversion technologies with the advantages of manageable CO2 capture and high energy conversion efficiency. Depending on the chemical looping reaction products generated, chemical looping technologies generally can be grouped into two types: chemical looping full oxidation (CLFO) and chemical looping partial oxidation (CLPO). In CLFO, carbonaceous fuels are fully oxidized to CO2 and H2O, as typically represented by chemical looping combustion with electricity as the primary product. In CLPO, however, carbonaceous fuels are partially oxidized, as typically represented by chemical looping gasification with syngas or hydrogen as the primary product. Both CLFO and CLPO share similar operational features; however, the optimum process configurations and the specific oxygen carriers used between them can vary significantly. Progress in both CLFO and CLPO is reviewed and analyzed with specific focus on oxygen carrier developments that characterize these technologies.

  8. Chemical Looping Technology: Oxygen Carrier Characteristics.

    PubMed

    Luo, Siwei; Zeng, Liang; Fan, Liang-Shih

    2015-01-01

    Chemical looping processes are characterized as promising carbonaceous fuel conversion technologies with the advantages of manageable CO2 capture and high energy conversion efficiency. Depending on the chemical looping reaction products generated, chemical looping technologies generally can be grouped into two types: chemical looping full oxidation (CLFO) and chemical looping partial oxidation (CLPO). In CLFO, carbonaceous fuels are fully oxidized to CO2 and H2O, as typically represented by chemical looping combustion with electricity as the primary product. In CLPO, however, carbonaceous fuels are partially oxidized, as typically represented by chemical looping gasification with syngas or hydrogen as the primary product. Both CLFO and CLPO share similar operational features; however, the optimum process configurations and the specific oxygen carriers used between them can vary significantly. Progress in both CLFO and CLPO is reviewed and analyzed with specific focus on oxygen carrier developments that characterize these technologies. PMID:25898071

  9. Straddle Carrier Interface and Dispatching System

    2012-09-13

    SCIDS is the Data Dispatching and Transfer Point (DDTP) component of a straddle carrier-based radiation detection system developed for the DOE Megaports Initiative for scanning shipping containers in transshipment ports. Its purpose is to communicate with a Radiation Detection Straddle Carrier (RDSC) developed by Detector Networks International, sending commands to the RDSC and receiving sensor data from the RDSC. Incoming sensor and status data from the RDSC is forwarded to a back-end data storage andmore » display system that is external to SCIDS. SCIDS provides a graphical user interface for port operations personnel that displays location and status of the RDSC and status of each container in the port, and accepts commands from the operator directing the scanning operations of the RDSC.« less

  10. LNG carrier using membrane tank system delivered

    SciTech Connect

    Not Available

    1993-12-06

    The world's first LNG carrier that incorporates the Technigaz Mark 3 membrane tank system was delivered in October to its owner, Asia LNG Transport Sdn. Bhd., a joint venture between Nippon Yusen K.K. and Perbadanan Nasional Shipping Line Berhad of Malaysia. NKK built the 18,800 cu m, fully double-hull carrier Aman Bintulu at its Tsu works. Construction was completed in September with more than 2 months of sea trials and gas tests using [minus]190 C. Liquid nitrogen and final gas trails with LNG. The orthogonally corrugated stainless membrane primary barrier and the triplex (aluminum foil/fiber glass cloth) composite-material secondary barrier prevent LNG from leaking in the event of an accident.

  11. Carrier cultures of simian foamy virus.

    PubMed

    Clarke, J K; Samuels, J; Dermott, E; Gay, F W

    1970-05-01

    The production of cultures of HEp-2 and BHK-21 cells persistently infected with a type 1 simian foamy virus is described. After infection, HEp-2 cells showed no structural changes, whereas BHK-21 cells lost their normal spindle shape and showed mitochondrial damage, and some cells contained many lysosomes. Thin sections also showed that a few BHK-21 cells contained virus particles in low concentration, and infectious virus could be isolated from both the cells and the supernatant fluid. No virus was seen in thin sections of HEp-2 cells, although infectious virus in low titer could be recovered intermittently from lysed cells. Both carrier cultures were immune to challenge with homologous virus and antigen could be detected in over 90% of the cells even after growth for 9 weeks in the presence of virus-neutralizing serum. The distribution of antigen in carrier cultures of both cell types is described and compared with that seen in cytocidal infections. PMID:4986851

  12. Straddle Carrier Interface and Dispatching System

    SciTech Connect

    2012-09-13

    SCIDS is the Data Dispatching and Transfer Point (DDTP) component of a straddle carrier-based radiation detection system developed for the DOE Megaports Initiative for scanning shipping containers in transshipment ports. Its purpose is to communicate with a Radiation Detection Straddle Carrier (RDSC) developed by Detector Networks International, sending commands to the RDSC and receiving sensor data from the RDSC. Incoming sensor and status data from the RDSC is forwarded to a back-end data storage and display system that is external to SCIDS. SCIDS provides a graphical user interface for port operations personnel that displays location and status of the RDSC and status of each container in the port, and accepts commands from the operator directing the scanning operations of the RDSC.

  13. Carrier synchronization and detection of polyphase signals.

    NASA Technical Reports Server (NTRS)

    Lindsey, W. C.; Simon, M. K.

    1972-01-01

    Digital communication networks used for the distribution of high-speed digital information are currently the subject of design studies for many civil and military applications. This paper presents results that are useful in such studies as well as in network planning. In particular, the paper is concerned with the problems of carrier synchronization and noisy reference detection of polyphase signals. Reconstruction of coherent references for the detection of polyphase signals is considered and analyzed for three carrier reconstruction loops, namely, Nth power (multiply-and-divide) loops, generalized Costas (I-Q) loops, and extensions of data-aided (modulation wipeoff) loops. General expressions for the error probability are developed when the reconstructed reference signals are noisy.

  14. Carrier Modulation Via Waveform Probability Density Function

    NASA Technical Reports Server (NTRS)

    Williams, Glenn L.

    2006-01-01

    Beyond the classic modes of carrier modulation by varying amplitude (AM), phase (PM), or frequency (FM), we extend the modulation domain of an analog carrier signal to include a class of general modulations which are distinguished by their probability density function histogram. Separate waveform states are easily created by varying the pdf of the transmitted waveform. Individual waveform states are assignable as proxies for digital one's or zero's. At the receiver, these states are easily detected by accumulating sampled waveform statistics and performing periodic pattern matching, correlation, or statistical filtering. No fundamental physical laws are broken in the detection process. We show how a typical modulation scheme would work in the digital domain and suggest how to build an analog version. We propose that clever variations of the modulating waveform (and thus the histogram) can provide simple steganographic encoding.

  15. Mobility of charge carriers in disordered dielectrics

    NASA Astrophysics Data System (ADS)

    Tiotnev, A. P.; Boev, S. G.; Sadovnichii, D. N.

    1994-07-01

    We compare experimental data on the mobility of holes (the majority charge carriers) in polyepoxy-propylcarbazole, measured using the time-of-flight technique (drift mobility) and the nonsteady-state radiation-induced electrical conductivity method (effective mobility). We show that these two quantities are quite different in the dispersive transport regime; and while the second quantity is a characteristic of the material, the first quantity depends in a complicated fashion on the ratio of the electric field strength to the sample thickness. The “untreated” data on drift mobility measurements using the time-of-flight technique do not have direct physical meaning and cannot be compared with the conclusions of modern microscopic theories of the mobility of charge carriers in disordered matrices.

  16. Psychiatric diagnoses aboard an aircraft carrier.

    PubMed

    Bohnker, B; McEwen, G; Blanco, J; Feeks, E

    1992-11-01

    A descriptive study was conducted for 150 consecutive patients with a psychiatric diagnosis evaluated over 11 months by the medical staff onboard an aircraft carrier. Patients with sole diagnosis of alcohol abuse or dependence were excluded. Axis II diagnoses, or personality disorders, were more common (N = 120) than Axis I diagnoses (N = 46). The most common Axis I diagnoses were adjustment disorder and major depression. Axis II diagnoses were significantly more likely (OR = 7.33, 95% CI 4.45-12.16, p = 0.000) in sailors less than 23 years of age compared to ship's population. Suicide behavior was demonstrated in 68% (102/150) of the patient population. This study emphasized the requirement for extensive psychiatric training for the clinical aerospace medicine specialists providing operational support to aircraft carrier crews.

  17. Screening-induced carrier transport in silicene.

    PubMed

    Hu, Bo

    2015-06-24

    Based on the Boltzmann transport equation in the MRT approximation, we present a theory to investigate low-field carrier transport in dual-gated silicene FETs by taking into account screened charged impurity scattering, which is the most likely scattering mechanism limiting the conductivity. Static RPA dielectric screening is also included in the conductivity calculation to study temperature-dependent silicene transport. It is found that both calculated conductivity and band gap not only depend strongly on carrier sheet density, but also depend strongly on effective offset density. More importantly, screening-induced metal-insulator-transition phenomena in buckled silicene can be observed theoretically, which is similar to that obtained in monolayer graphene.

  18. Insights into the roles of carrier microstructure in adhesive/carrier-based dry powder inhalation mixtures: Carrier porosity and fine particle content.

    PubMed

    Shalash, Ahmed O; Molokhia, Abdulla M; Elsayed, Mustafa M A

    2015-10-01

    To gain insights into complex interactions in carrier-based dry powder inhalation mixtures, we studied the relationships between the carrier microstructural characteristics and performance. We used mercury intrusion porosimetry to measure the microstructural characteristics and to also derive the air permeability of eight carriers. We evaluated the performances of inhalation mixtures of each of these carriers and fluticasone propionate after aerosolization from an Aerolizer®. We did not observe a simple relationship between the carrier total porosity and the performance. Classification of the porosity according to pore size, however, provided interesting insights. The carrier nanoporosity, which refers to pores smaller than micronized drug particles, has a positive influence on the performance. Nanopores reduce the carrier effective contact area and the magnitude of interparticulate adhesion forces in inhalation mixtures. The carrier microporosity, which refers to pores similar in size to drug particles, also has a positive influence on the performance. During mixing, micropores increase the effectiveness of frictional and press-on forces, which are responsible for breaking up of cohesive drug agglomerates and for distribution of drug particles over the carrier surface. On the other hand, the carrier macroporosity, which refers to pores larger than drug particles, apparently has a negative influence on the performance. This influence is likely mediated via the effects of macropores on the powder bed tensile strength and fluidization behavior. The air permeability better represents these effects. The inhalation mixture performance improved as the carrier air permeability decreased. Interestingly, as the carrier fine particle content increased, the carrier microporosity increased and the carrier air permeability decreased. This proposes a new mechanism for the positive effect of fine excipient materials on the performance of carrier-based inhalation mixtures. Fine

  19. PLUTONIUM CARRIER METATHESIS WITH ORGANIC REAGENT

    DOEpatents

    Thompson, S.G.

    1958-07-01

    A method is described for converting a plutonium containing bismuth phosphate carrier precipitate Into a compositton more readily soluble in acid. The method consists of dissolving the bismuth phosphate precipitate in an aqueous solution of alkali metal hydroxide, and adding one of a certaia group of organic compounds, e.g., polyhydric alcohols or a-hydrorycarboxylic acids. The mixture is then heated causiing formation of a bismuth hydroxide precipitate containing plutonium which may be readily dissolved in nitric acid for further processing.

  20. Cyclic spectrum based carrier recovery for OQPSK

    NASA Astrophysics Data System (ADS)

    Peng, Hua; Li, Jing

    2011-10-01

    A union carrier synchronization scheme of feed-forward frequency offset estimation and PLL for OQPSK signals is discussed in this paper. A feed-forward frequency offset estimator is developed based on the cyclic spectrum of the received signal. In order to suppress channel noise, an improved strategy is proposed. Simulations show that the presented scheme can achieve steady state much more quickly than conventional Costas loop. At the same time, the steady error of the union scheme is also smaller.

  1. Organized polysaccharide fibers as stable drug carriers.

    PubMed

    Janaswamy, Srinivas; Gill, Kristin L; Campanella, Osvaldo H; Pinal, Rodolfo

    2013-04-15

    Many challenges arise during the development of new drug carrier systems, and paramount among them are safety, solubility and controlled release requirements. Although synthetic polymers are effective, the possibility of side effects imposes restrictions on their acceptable use and dose limits. Thus, a new drug carrier system that is safe to handle and free from side effects is very much in need and food grade polysaccharides stand tall as worthy alternatives. Herein, we demonstrate for the first time the feasibility of sodium iota-carrageenan fibers and their distinctive water pockets to embed and release a wide variety of drug molecules. Structural analysis has revealed the existence of crystalline network in the fibers even after encapsulating the drug molecules, and iota-carrageenan maintains its characteristic and reproducible double helical structure suggesting that the composites thus produced are reminiscent of cocrystals. The melting properties of iota-carrageenan:drug complexes are distinctly different from those of either drug or iota-carrageenan fiber. The encapsulated drugs are released in a sustained manner from the fiber matrix. Overall, our research provides an elegant opportunity for developing effective drug carriers with stable network toward enhancing and/or controlling bioavailability and extending shelf-life of drug molecules using GRAS excipients, food polysaccharides, that are inexpensive and non-toxic.

  2. Hot Carrier Extraction with Plasmonic Broadband Absorbers.

    PubMed

    Ng, Charlene; Cadusch, Jasper J; Dligatch, Svetlana; Roberts, Ann; Davis, Timothy J; Mulvaney, Paul; Gómez, Daniel E

    2016-04-26

    Hot charge carrier extraction from metallic nanostructures is a very promising approach for applications in photocatalysis, photovoltaics, and photodetection. One limitation is that many metallic nanostructures support a single plasmon resonance thus restricting the light-to-charge-carrier activity to a spectral band. Here we demonstrate that a monolayer of plasmonic nanoparticles can be assembled on a multistack layered configuration to achieve broadband, near-unit light absorption, which is spatially localized on the nanoparticle layer. We show that this enhanced light absorbance leads to ∼40-fold increases in the photon-to-electron conversion efficiency by the plasmonic nanostructures. We developed a model that successfully captures the essential physics of the plasmonic hot electron charge generation and separation in these structures. This model also allowed us to establish that efficient hot carrier extraction is limited to spectral regions where (i) the photons have energies higher than the Schottky junctions and (ii) the absorption of light is localized on the metal nanoparticles.

  3. Photoinduced carrier annihilation in silicon pn junction

    NASA Astrophysics Data System (ADS)

    Sameshima, Toshiyuki; Motoki, Takayuki; Yasuda, Keisuke; Nakamura, Tomohiko; Hasumi, Masahiko; Mizuno, Toshihisa

    2015-08-01

    We report analysis of the photo-induced minority carrier effective lifetime (τeff) in a p+n junction formed on the top surfaces of a n-type silicon substrate by ion implantation of boron and phosphorus atoms at the top and bottom surfaces followed by activation by microwave heating. Bias voltages were applied to the p+ boron-doped surface with n+ phosphorus-doped surface kept at 0 V. The values of τeff were lower than 1 × 10-5 s under the reverse-bias condition. On the other hand, τeff markedly increased to 1.4 × 10-4 s as the forward-bias voltage increased to 0.7 V and then it leveled off when continuous-wave 635 nm light was illuminated at 0.74 mW/cm2 on the p+ surface. The carrier annihilation velocity S\\text{p + } at the p+ surface region was numerically estimated from the experimental τeff. S\\text{p + } ranged from 4000 to 7200 cm/s under the reverse-bias condition when the carrier annihilation velocity S\\text{n + } at the n+ surface region was assumed to be a constant value of 100 cm/s. S\\text{p + } markedly decreased to 265 cm/s as the forward-bias voltage increased to 0.7 V.

  4. Organized polysaccharide fibers as stable drug carriers

    PubMed Central

    Janaswamy, Srinivas; Gill, Kristin L.; Campanella, Osvaldo H.; Pinal, Rodolfo

    2013-01-01

    Many challenges arise during the development of new drug carrier systems, and paramount among them are safety, solubility and controlled release requirements. Although synthetic polymers are effective, the possibility of side effects imposes restrictions on their acceptable use and dose limits. Thus, a new drug carrier system that is safe to handle and free from side effects is very much in need and food grade polysaccharides stand tall as worthy alternatives. Herein, we demonstrate for the first time the feasibility of sodium iota-carrageenan fibers and their distinctive water pockets to embed and release a wide variety of drug molecules. Structural analysis has revealed the existence of crystalline network in the fibers even after encapsulating the drug molecules, and iota-carrageenan maintains its characteristic and reproducible double helical structure suggesting that the composites thus produced are reminiscent of cocrystals. The melting properties of iota-carrageenan:drug complexes are distinctly different from those of either drug or iota-carrageenan fiber. The encapsulated drugs are released in a sustained manner from the fiber matrix. Overall, our research provides an elegant opportunity for developing effective drug carriers with stable network toward enhancing and/or controlling bioavailability and extending shelf-life of drug molecules using GRAS excipients, food polysaccharides, that are inexpensive and non–toxic. PMID:23544530

  5. PLUTONIUM PURIFICATION PROCESS EMPLOYING THORIUM PYROPHOSPHATE CARRIER

    DOEpatents

    King, E.L.

    1959-04-28

    The separation and purification of plutonium from the radioactive elements of lower atomic weight is described. The process of this invention comprises forming a 0.5 to 2 M aqueous acidffc solution containing plutonium fons in the tetravalent state and elements with which it is normally contaminated in neutron irradiated uranium, treating the solution with a double thorium compound and a soluble pyrophosphate compound (Na/sub 4/P/sub 2/O/sub 7/) whereby a carrier precipitate of thorium A method is presented of reducing neptunium and - trite is advantageous since it destroys any hydrazine f so that they can be removed from solutions in which they are contained is described. In the carrier precipitation process for the separation of plutonium from uranium and fission products including zirconium and columbium, the precipitated blsmuth phosphate carries some zirconium, columbium, and uranium impurities. According to the invention such impurities can be complexed and removed by dissolving the contaminated carrier precipitate in 10M nitric acid, followed by addition of fluosilicic acid to about 1M, diluting the solution to about 1M in nitric acid, and then adding phosphoric acid to re-precipitate bismuth phosphate carrying plutonium.

  6. 21 CFR 58.113 - Mixtures of articles with carriers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Mixtures of articles with carriers. 58.113 Section... GOOD LABORATORY PRACTICE FOR NONCLINICAL LABORATORY STUDIES Test and Control Articles § 58.113 Mixtures of articles with carriers. (a) For each test or control article that is mixed with a carrier,...

  7. 21 CFR 58.113 - Mixtures of articles with carriers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Mixtures of articles with carriers. 58.113 Section... GOOD LABORATORY PRACTICE FOR NONCLINICAL LABORATORY STUDIES Test and Control Articles § 58.113 Mixtures of articles with carriers. (a) For each test or control article that is mixed with a carrier,...

  8. 21 CFR 58.113 - Mixtures of articles with carriers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Mixtures of articles with carriers. 58.113 Section... GOOD LABORATORY PRACTICE FOR NONCLINICAL LABORATORY STUDIES Test and Control Articles § 58.113 Mixtures of articles with carriers. (a) For each test or control article that is mixed with a carrier,...

  9. 14 CFR 296.3 - Indirect cargo air carrier.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Indirect cargo air carrier. 296.3 Section... PROCEEDINGS) ECONOMIC REGULATIONS INDIRECT AIR TRANSPORTATION OF PROPERTY General § 296.3 Indirect cargo air carrier. An indirect cargo air carrier is any U.S. citizen who undertakes to engage indirectly in...

  10. 14 CFR 296.3 - Indirect cargo air carrier.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Indirect cargo air carrier. 296.3 Section... PROCEEDINGS) ECONOMIC REGULATIONS INDIRECT AIR TRANSPORTATION OF PROPERTY General § 296.3 Indirect cargo air carrier. An indirect cargo air carrier is any U.S. citizen who undertakes to engage indirectly in...

  11. 14 CFR 296.3 - Indirect cargo air carrier.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Indirect cargo air carrier. 296.3 Section... PROCEEDINGS) ECONOMIC REGULATIONS INDIRECT AIR TRANSPORTATION OF PROPERTY General § 296.3 Indirect cargo air carrier. An indirect cargo air carrier is any U.S. citizen who undertakes to engage indirectly in...

  12. 49 CFR 373.101 - Motor carrier bills of lading.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... information as prescribed in 49 CFR part 379. ... 49 Transportation 5 2012-10-01 2012-10-01 false Motor carrier bills of lading. 373.101 Section 373... BILLS Motor Carrier Receipts and Bills § 373.101 Motor carrier bills of lading. Every motor...

  13. 49 CFR 373.101 - Motor carrier bills of lading.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... information as prescribed in 49 CFR part 379. ... 49 Transportation 5 2014-10-01 2014-10-01 false Motor carrier bills of lading. 373.101 Section 373... BILLS Motor Carrier Receipts and Bills § 373.101 Motor carrier bills of lading. Every motor...

  14. 14 CFR 252.5 - Smoking ban: foreign air carriers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Smoking ban: foreign air carriers. 252.5... PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.5 Smoking ban: foreign air carriers. (a) Foreign air carriers shall prohibit smoking on all scheduled passenger flight segments: (1) Between...

  15. 14 CFR 252.5 - Smoking ban: foreign air carriers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Smoking ban: foreign air carriers. 252.5... PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.5 Smoking ban: foreign air carriers. (a) Foreign air carriers shall prohibit smoking on all scheduled passenger flight segments: (1) Between...

  16. 14 CFR 252.3 - Smoking ban: air carriers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Smoking ban: air carriers. 252.3 Section... PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.3 Smoking ban: air carriers. Air carriers shall prohibit smoking on all scheduled passenger flights....

  17. 14 CFR 252.5 - Smoking ban: foreign air carriers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Smoking ban: foreign air carriers. 252.5... PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.5 Smoking ban: foreign air carriers. (a) Foreign air carriers shall prohibit smoking on all scheduled passenger flight segments: (1) Between...

  18. 14 CFR 252.3 - Smoking ban: air carriers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Smoking ban: air carriers. 252.3 Section... PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.3 Smoking ban: air carriers. Air carriers shall prohibit smoking on all scheduled passenger flights....

  19. 14 CFR 252.3 - Smoking ban: air carriers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Smoking ban: air carriers. 252.3 Section... PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.3 Smoking ban: air carriers. Air carriers shall prohibit smoking on all scheduled passenger flights....

  20. 14 CFR 252.3 - Smoking ban: air carriers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Smoking ban: air carriers. 252.3 Section... PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.3 Smoking ban: air carriers. Air carriers shall prohibit smoking on all scheduled passenger flights....

  1. 14 CFR 252.5 - Smoking ban: foreign air carriers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Smoking ban: foreign air carriers. 252.5... PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.5 Smoking ban: foreign air carriers. (a) Foreign air carriers shall prohibit smoking on all scheduled passenger flight segments: (1) Between...

  2. 14 CFR 252.5 - Smoking ban: foreign air carriers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Smoking ban: foreign air carriers. 252.5... PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.5 Smoking ban: foreign air carriers. (a) Foreign air carriers shall prohibit smoking on all scheduled passenger flight segments: (1) Between...

  3. 47 CFR 64.1190 - Preferred carrier freezes.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... procedures necessary to lift a preferred carrier freeze; an explanation that these steps are in addition to... selection unless he or she lifts the freeze. (iii) An explanation of any charges associated with the... unable to make a change in carrier selection unless she or he lifts the preferred carrier freeze; and...

  4. 47 CFR 64.1190 - Preferred carrier freezes.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... procedures necessary to lift a preferred carrier freeze; an explanation that these steps are in addition to... selection unless he or she lifts the freeze. (iii) An explanation of any charges associated with the... unable to make a change in carrier selection unless she or he lifts the preferred carrier freeze; and...

  5. 47 CFR 73.1540 - Carrier frequency measurements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Carrier frequency measurements. 73.1540 Section... measurements. (a) The carrier frequency of each AM and FM station and the visual carrier frequency and the... departure limits. (c) The primary standard of frequency for radio frequency measurements is the...

  6. 47 CFR 73.1540 - Carrier frequency measurements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Carrier frequency measurements. 73.1540 Section... measurements. (a) The carrier frequency of each AM and FM station and the visual carrier frequency and the... departure limits. (c) The primary standard of frequency for radio frequency measurements is the...

  7. 14 CFR 296.3 - Indirect cargo air carrier.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Indirect cargo air carrier. 296.3 Section... PROCEEDINGS) ECONOMIC REGULATIONS INDIRECT AIR TRANSPORTATION OF PROPERTY General § 296.3 Indirect cargo air carrier. An indirect cargo air carrier is any U.S. citizen who undertakes to engage indirectly in...

  8. 19 CFR 113.64 - International carrier bond conditions.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 19 Customs Duties 1 2012-04-01 2012-04-01 false International carrier bond conditions. 113.64...; DEPARTMENT OF THE TREASURY CUSTOMS BONDS Customs Bond Conditions § 113.64 International carrier bond conditions. A bond for international carriers shall contain the conditions listed in this section and may...

  9. 19 CFR 113.64 - International carrier bond conditions.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 19 Customs Duties 1 2013-04-01 2013-04-01 false International carrier bond conditions. 113.64...; DEPARTMENT OF THE TREASURY CUSTOMS BONDS Customs Bond Conditions § 113.64 International carrier bond conditions. A bond for international carriers shall contain the conditions listed in this section and may...

  10. 47 CFR 69.601 - Exchange carrier association.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 3 2011-10-01 2011-10-01 false Exchange carrier association. 69.601 Section 69...) ACCESS CHARGES Exchange Carrier Association § 69.601 Exchange carrier association. (a) An association... Common Line revenue requirement, pay long term support to association Common Line tariff participants,...

  11. 47 CFR 69.601 - Exchange carrier association.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 3 2010-10-01 2010-10-01 false Exchange carrier association. 69.601 Section 69...) ACCESS CHARGES Exchange Carrier Association § 69.601 Exchange carrier association. (a) An association... Common Line revenue requirement, pay long term support to association Common Line tariff participants,...

  12. 14 CFR 158.69 - Recordkeeping and auditing: Collecting carriers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Recordkeeping and auditing: Collecting carriers. 158.69 Section 158.69 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF....69 Recordkeeping and auditing: Collecting carriers. (a) Collecting carriers shall establish...

  13. 49 CFR 1139.22 - Revenue data for study carriers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 8 2012-10-01 2012-10-01 false Revenue data for study carriers. 1139.22 Section 1139.22 Transportation Other Regulations Relating to Transportation (Continued) SURFACE TRANSPORTATION... Intercity Bus Industry § 1139.22 Revenue data for study carriers. The study carriers, as identified...

  14. 49 CFR 1139.22 - Revenue data for study carriers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 8 2013-10-01 2013-10-01 false Revenue data for study carriers. 1139.22 Section 1139.22 Transportation Other Regulations Relating to Transportation (Continued) SURFACE TRANSPORTATION... Intercity Bus Industry § 1139.22 Revenue data for study carriers. The study carriers, as identified...

  15. Geochemistry of dissolved aluminum at low pH: Extent and significance of Al-Fe(III) coprecipitation below pH 4.0

    NASA Astrophysics Data System (ADS)

    Sánchez-España, Javier; Yusta, Iñaki; Gray, Jennifer; Burgos, William D.

    2016-02-01

    This work examines the geochemical behavior of dissolved aluminum in sulfate-rich acidic waters. Our observations were obtained during several years of geochemical and mineralogical research in the San Telmo acidic pit lake and other pit lakes of SW Spain. The work includes scanning and transmission electron microscopy (SEM, TEM) of suspended mineral colloids found in deep lake waters. Energy dispersive spectroscopy (EDS) coupled to scanning and high resolution transmission electron microscopy (STEM, HRTEM) revealed not only the presence and formation of discrete, sub-micron Al solids like alunite, but also the abundance and distribution of Al into Fe(III) phases typical of acid mine drainage, such as schwertmannite and jarosite, at a nanometric resolution. The main conclusion emerging from our work is that the fate and transport of Al at low pH (<4.0) can be largely influenced by adsorption on and/or coprecipitation with both schwertmannite and jarosite. Under the geochemical conditions studied (SO42- = 10-2 M, Fe(III) ∼ Al = 10-3 M), alunite formation may occur at pH > 3.3, as suggested by mineralogical observations and geochemical modelling. Below this pH, and contrary to the extended assumption, Al is not truly conservative, and in the presence of ferric iron, both metals may co-precipitate at a substantial extent to form either particles of Al-rich schwertmannite (containing up to ca. 8 at.% Al with [Fe/(Fe + Al)] = 0.77) and/or crystals of H3O+- to K+-jarosite (containing up to ca. 10 at.% Al with [Fe/(Fe + Al)] = 0.54). This Al incorporation seems to take place by adsorption on particle surfaces in schwertmannite and by atomic substitution for Fe3+ in jarosite. Alunite is also unstable at this low pH range with respect to jarosite, which may lead either to isomorphic transformation and/or to chemically zoned crystals with jarositic rims around previously formed alunite cores. As a whole, the compositional spectrum of the analyzed jarosites and alunites

  16. 49 CFR 369.1 - Annual reports of motor carriers of property, motor carriers of household goods, and dual...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... classification criteria, see § 369.2. (b) Quarterly Report Form QFR. All class I common motor carriers of... M. All class I and class II common and contract carriers of property, including household goods...

  17. Sterol carrier and lipid transfer proteins.

    PubMed

    Scallen, T J; Pastuszyn, A; Noland, B J; Chanderbhan, R; Kharroubi, A; Vahouny, G V

    1985-09-01

    The discovery of the sterol carrier and lipid transfer proteins was largely a result of the findings that cells contained cytosolic factors which were required either for the microsomal synthesis of cholesterol or which could accelerate the transfer or exchange of phospholipids between membrane preparations. There are two sterol carrier proteins present in rat liver cytosol. Sterol carrier protein 1 (SCP1) (Mr 47 000) participates in the microsomal conversion of squalene to lanosterol, and sterol carrier protein 2 (SCP2) (Mr 13 500) participates in the microsomal conversion of lanosterol to cholesterol. In addition SCP2 also markedly stimulates the esterification of cholesterol by rat liver microsomes, as well as the conversion of cholesterol to 7 alpha-hydroxycholesterol - the major regulatory step in bile acid formation. Also, SCP2 is required for the intracellular transfer of cholesterol from adrenal cytoplasmic lipid inclusion droplets to mitochondria for steroid hormone production, as well as cholesterol transfer from the outer to the inner mitochondrial membrane. SCP2 is identical to the non-specific phospholipid exchange protein. While SCP2 is capable of phospholipid exchange between artificial donors/acceptors, e.g. liposomes and microsomes, it does not enhance the release of lipids other than unesterified cholesterol from natural donors/acceptors, e.g. adrenal lipid inclusion droplets, and will not enhance exchange of labeled phosphatidylcholine between lipid droplets and mitochondria. Careful comparison of SCP2 and fatty acid binding protein (FABP) using six different assay procedures demonstrates separate and distinct physiological functions for each protein, with SCP2 participating in reactions involving sterols and FABP participating in reactions involving fatty acid binding and/or transport. Furthermore, there is no overlap in substrate specificities, i.e. FABP does not possess sterol carrier protein activity and SCP2 does not specifically bind or

  18. Reduced macular function in ABCA4 carriers

    PubMed Central

    2015-01-01

    Purpose To study retinal function and morphology in ABCA4 carriers to investigate if ABCA4 carriership is associated with any functional or morphological changes and, if so, to explore whether certain mutations may be associated with particularly severe alterations. Methods Eighteen subjects were recruited by means of being the parents of 10 teenagers/young adults with genetically confirmed ABCA4-associated retinal degenerations. The teenagers/young adults are well-known patients and have been followed in our clinic for many years. The eighteen subjects underwent careful ophthalmological examinations, including fundus photography and autofluorescence imaging, Goldmann perimetry, optical coherence tomography (OCT), full-field electroretinography (ffERG), multifocal electroretinography (mERG), and ABCA4 gene sequencing. The ffERG and mERG results were compared with those of healthy controls. Results All subjects carried at least one ABCA4 mutation. Two subjects were compound heterozygous and therefore were excluded from the group-wise statistical analysis. Thirteen different ABCA4 mutations were found. C.2894 A>G (5/18) and c.768 G>T (4/18) were most common. Fourteen of 16 ABCA4 carriers demonstrated significantly altered mERG parameters (reduced amplitudes and/or delayed implicit times (ITs)) compared to normal values. In addition, the two subjects with compound heterozygous ABCA4 mutations had altered mERG parameters. A statistical comparison to the control group showed significantly reduced amplitudes and delayed ITs; p≤0.003 for all mERG parameters. FfERG parameters were altered in two ABCA4 carriers and one of the subjects with compound heterozygous ABCA4 mutations (reduced amplitude and delayed IT for the 30 Hz flicker ERG). No significant alterations were found for the whole group of ABCA4 carriers compared to the ffERG control group. Fundus photographs showed subtle to extensive pigmentary changes in several ABCA4 carriers. Conclusions In this study, ABCA4

  19. Improvements in electrical and dielectric properties of substituted multiferroic LaMnO{sub 3} based nanostructures synthesized by co-precipitation method

    SciTech Connect

    Mahmood, Azhar; Warsi, Muhammad Farooq; Ashiq, Muhammad Naeem; Sher, Muhammad

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► Simultaneous double ion substitutions philosophy is introduced in LaMnO{sub 3}. ► La{sub 1−x}Gd{sub x}Mn{sub 1−y}Cr{sub y}O{sub 3} nanoparticles are not reported previously. ► La{sub 1−x}Gd{sub x}Mn{sub 1−y}Cr{sub y}O{sub 3} nanoparticles are synthesized by co-precipitation method. ► The 12 fold increase in resistivity of LaMnO{sub 3} nanostructures is observed. -- Abstract: A series of La{sub 1−x}Gd{sub x}Mn{sub 1−y}Cr{sub y}O{sub 3} nanoparticles (where x, y = 0, 0.25, 0.50, 0.75 and 1.0) has been synthesized by the chemical co-precipitation method, involving double ion substitution philosophy. The nanoparticles were characterized by thermo gravimetric analysis (TGA), X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, vibrating sample magnetometer (VSM), DC electrical resistivity and dielectric measurements. The XRD and FTIR analysis confirmed the single orthorhombic phase and the crystallite size were found in the range of 16–34 nm. DC resistivity exhibited very interesting behavior which increased from 1.41 × 10{sup 8} to 16.35 ± 0.2 × 10{sup 8} Ω cm upon complete double ions replacement of La and Mn with Gd and Cr, respectively. This very high resistivity variation upon substitution definitely would open new avenues for applications of these materials in microwave devices and other related areas. The dielectric properties of these nanoparticles were also studied at room temperature in the range of 6 kHz to 5 MHz and the maximum dielectric behavior (ε′ = 2.86 × 10{sup 3}, tan δ = 5.41, ε″ = 15.5 × 10{sup 3}) was exhibited by La{sub 0.75}Gd{sub 0.25}Mn{sub 0.75}Cr{sub 0.25}O{sub 3} at 6 kHz. Hysteresis loops measurements showed that the synthesized nanomaterials are paramagnetic in nature at room temperature.

  20. Drug delivery system for an anticancer agent, chlorogenate-Zn/Al-layered double hydroxide nanohybrid synthesised using direct co-precipitation and ion exchange methods

    SciTech Connect

    Barahuie, Farahnaz; Hussein, Mohd Zobir; Arulselvan, Palanisamy; Fakurazi, Sharida; Zainal, Zulkarnain

    2014-09-15

    A nano-structured drug-inorganic clay hybrid involving an active anticancer compound, which is chlorogenic acid (CA) intercalated into Zn/Al-layered double hydroxide, has been assembled via ion-exchange and co-precipitation methods to form a nanohybrid CZAE (a chlorogenic acid-Zn/Al nanohybrid synthesised using an ion-exchange method) and CZAC (a chlorogenic acid-Zn/Al nanohybrid synthesised using a direct method), respectively. The X-ray diffraction (XRD) results confirmed that the CA-LDH had a hybrid structure in which the anionic chlorogenate is arranged between the interlayers as a horizontal monolayer at 90 and 20° angles from the x axis for CZAE and CZAC, respectively. Both nanohybrids have the properties of mesoporous materials. The high loading percentage of chlorogenic acid (approximately 43.2% for CZAE and 45.3% for CZAC) with basal spacings of 11.7 and 12.6 Å for CZAE and CZAC, respectively, corroborates the successful intercalation of chlorogenic acid into the interlayer gallery of layered double hydroxides. Free chlorogenic acid and the synthesised nanocomposites (CZAE, CZAC) were assessed for their cytotoxicity against various cancer cells. The Fourier transform infrared data supported the formation of both nanohybrids, and a thermal analysis showed that the nanohybrids are more thermally stable than their counterparts. The chlorogenate shows a sustained release, and the release rate of chlorogenate from CZAE and CZAC nanohybrids at pH 7.4 is remarkably lower than that at pH 4.8 due to their different release mechanisms. The release rate of chlorogenate from both nanohybrids can be described as pseudo-second order. The present investigation revealed the potential of the nanohybrids to enhance the in vitro anti-tumour effect of chlorogenic acid in liver and lung cancer cells in vitro. - Highlights: • We intercalated chlorogenic into Zn/Al-layered double hydroxide by ion-exchange and coprecipitation methods. • The two methods gave nanocomposites

  1. Transmission line model for strained quantum well lasers including carrier transport and carrier heating effects.

    PubMed

    Xia, Mingjun; Ghafouri-Shiraz, H

    2016-03-01

    This paper reports a new model for strained quantum well lasers, which are based on the quantum well transmission line modeling method where effects of both carrier transport and carrier heating have been included. We have applied this new model and studied the effect of carrier transport on the output waveform of a strained quantum well laser both in time and frequency domains. It has been found that the carrier transport increases the turn-on, turn-off delay times and damping of the quantum well laser transient response. Also, analysis in the frequency domain indicates that the carrier transport causes the output spectrum of the quantum well laser in steady state to exhibit a redshift which has a narrower bandwidth and lower magnitude. The simulation results of turning-on transients obtained by the proposed model are compared with those obtained by the rate equation laser model. The new model has also been used to study the effects of pump current spikes on the laser output waveforms properties, and it was found that the presence of current spikes causes (i) wavelength blueshift, (ii) larger bandwidth, and (iii) reduces the magnitude and decreases the side-lobe suppression ratio of the laser output spectrum. Analysis in both frequency and time domains confirms that the new proposed model can accurately predict the temporal and spectral behaviors of strained quantum well lasers. PMID:26974607

  2. Carrier Transport Mechanism in Single Crystalline Organic Semiconductor Thin Film Elucidated by Visualized Carrier Motion.

    PubMed

    Matsubara, Kohei; Abe, Kentaro; Manaka, Takaaki; Iwamoto, Mitsumasa

    2016-04-01

    Time-resolved microscopic second harmonic generation (TRM-SHG) measurement was conducted to evaluate temperature dependence of the anisotropic carrier transport process in 6,13-Bis(triisopropylsilylethynyl) (TIPS) pentacene single crystalline domains for two orthogonal directions. Enhancement of the electric field induced SHG (EFI-SHG) signal at the electrode edge at low temperature suggests the presence of potential drop in the injection process. We directly evaluated temperature dependence of the carrier mobility by taking into account the potential drop, and concluded that the Marcus theory is appropriate to interpret the carrier transport in anisotropic TIPS pentacene thin film. TRM-SHG method is a facile and effective way to directly visualize transport process in anisotropic materials and to evaluate injection and transport processes simultaneously. PMID:27451638

  3. Plasmon-induced hot carriers in metallic nanoparticles.

    PubMed

    Manjavacas, Alejandro; Liu, Jun G; Kulkarni, Vikram; Nordlander, Peter

    2014-08-26

    Plasmon-induced hot carrier formation is attracting an increasing research interest due to its potential for applications in photocatalysis, photodetection and solar energy harvesting. However, despite very significant experimental effort, a comprehensive theoretical description of the hot carrier generation process is still missing. In this work we develop a theoretical model for the plasmon-induced hot carrier process and apply it to spherical silver nanoparticles and nanoshells. In this model, the conduction electrons of the metal are described as free particles in a finite spherical potential well, and the plasmon-induced hot carrier production is calculated using Fermi’s golden rule. We show that the inclusion of many-body interactions has only a minor influence on the results. Using the model we calculate the rate of hot carrier generation, finding that it closely follows the spectral profile of the plasmon. Our analysis reveals that particle size and hot carrier lifetime play a central role in determining both the production rate and the energy distribution of the hot carriers. Specifically, larger nanoparticle sizes and shorter lifetimes result in higher carrier production rates but smaller energies, and vice versa. We characterize the efficiency of the hot carrier generation process by introducing a figure of merit that measures the number of high energy carriers generated per plasmon. Furthermore, we analyze the spatial distribution and directionality of these excitations. The results presented here contribute to the basic understanding of plasmon-induced hot carrier generation and provide insight for optimization of the process.

  4. [Influence of reaction time of urea hydrolysis-based co-precipitation on the structure of ZnAl layered double hydroxides and the phosphate adsorption].

    PubMed

    Lu, Ying; Cheng, Xiang; Xing, Bo; Sun, Zhong-en; Sun, De-zhi

    2012-08-01

    A series of ZnAl layered double hydroxides (LDHs) were prepared by urea hydrolysis-based homogeneous co-precipitation for studying their structure and phosphate adsorption capacities. The results show that all the samples exhibited a typical layered structure as the reaction time extended from 12 h to 96 h, whereas Zn/Al molar ratio in the ZnAls decreased from 2.06 to 0.70 and the specific surface area markedly increased to be 7.6-fold higher than that of ZnAl-12. Phosphate adsorption capacity of the ZnAl was in general increased gradually with the reaction time extension, which can be attributed to the surface area rising as well as the increased positive charge of LDHs layer caused by a higher proportion of Al. This reveals that physicochemical adsorption on LDHs surface would have played an important role during the phosphate adsorption. With a reaction time of 24 h, a high amount of exchangeable interlayer anions was observed, giving rise to a highest phosphate uptake of 34.1 mg x g(-1) by the ZnAl-24. It indicates the ion exchange was another major pathway for the phosphate removal. For all the ZnAls with different reaction times, the phosphate adsorption isotherms fit well with Langmuir-type equations; the adsorption kinetics followed pseudo-second-order models.

  5. Preparation of Y2O3:Eu3+, Tb3+ nanopowders with tunable luminescence by ammonium bicarbonate co-precipitation method

    NASA Astrophysics Data System (ADS)

    Shi, Hui; Zhang, Xi-Yan; Wang, Neng-Li; Dong, Wei-Li; Mi, Xiao-Yun

    2015-09-01

    Y2O3:Eu3+, Tb3+ nanopowders were prepared by co-precipitation method with NH4HCO3 as precipitant. The nanopowders with different calcined temperatures and Eu3+/Tb3+ doped ratio were characterized by X-ray Diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectrophotometer. The results showed that the nanopowders calcined at 1100°C for 2 h had a uniform distribution, high purity and good dispersibility. The particle size was in the range of 60-80 nm. The excitation spectra of Eu3+/Tb3+ co-doped phosphors were wide. The phosphors could emit the green light at the peak of 543 nm and the red light at the peak of 611 nm simultaneously under 276 nm or 300 nm excited. Because of the energy transfer between Tb3+ and Eu3+, the 543 nm emission of Tb3+ ion was weakened while the 611 nm emission of Eu3+ enhanced. The emissive colors of Y2O3:Eu3+, Tb3+ nanopowders could be adjusted from yellow-green to orange-red by changing the Eu3+/Tb3+ doping ratio.

  6. Investigation of the Role of Ce3+ Substituted Ions on Dielectric Properties of Co-Cr Ferrites Prepared by Co-precipitation Method

    NASA Astrophysics Data System (ADS)

    Mustafa, Ghulam; Islam, M. U.; Zhang, Wenli; Arshad, M. I.; Jamil, Yasir; Anwar, Hafeez; Murtaza, G.; Hussain, Mudassar; Ahmad, Mukhtar

    2016-07-01

    A series of a CoCr0.04Ce x Fe1.96-x O4 spinel ferrite system with 0 ≤ x ≤ 0.1 (in steps of 0.02) has been synthesized by the co-precipitation technique. The synthesized samples were characterized using a Fourier transform infrared spectroscope (FT-IR), Raman spectroscopy, a scanning electron microscope (SEM), and dielectric measurements. The typical FT-IR spectrum of the samples annealed at 850°C exhibited two frequency bands due to the formation of octahedral (B-site) and tetrahedral (A-site) clusters of metal oxide, respectively. The SEM images showed the spherical morphology of synthesized material and confirmed the grain size in the range of (0.33-0.44) μm. The decrease of permittivity with the increase of frequency in the range of 1 MHz to 3 GHz follows the Maxwell-Wagner model. Moreover, the Ce3+substituted materials have smaller values of loss tangent and dielectric constant especially for x = 0.10, which is favorable for the applications where low losses are desired. The value of ac (alternating current) conductivity increases with an increase in the frequency and decreases with Ce3+ substitution, which reflects the hopping mechanism at respective sites. Such characteristics of these materials may be suitable␣for potential applications such as electromagnetic attenuation materials, switching applications, and microwave devices.

  7. Effect of calcination temperature on the photocatalytic activity of TiO2 powders prepared by co-precipitation of TiCl3

    NASA Astrophysics Data System (ADS)

    Yudoyono, Gatut; Ichzan, Nur; Zharvan, Vicran; Daniyati, Rizqa; Santoso, Hadi; Indarto, Bachtera; Pramono, Yono Hadi; Zainuri, Mochamad; Darminto

    2016-04-01

    The adsorption of basic dye methylene blue (MB) onto titanium dioxide (titania) powder that were prepared by coprecipitation method of TiCl3 and NH4OH as iniatial material with different calcination temperature was studied to examine the photocatalytic activity. Synthesis process carried out by the solution pH was adjusted to be 8. Effect of calcination temperature on the titania powder were characterized with Differential Scanning Calorimetry/Thermogravimetry (DSC/TG), X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM). The result of TG and XRD showed that the NH4Cl decomposed between 235-372°C. The XRD result showed that the anatase TiO2 only contained a single phase when the calcination temperature of the precursor at 800°C, and over which it began to grow rutile phase. The influence of synthesis condition on the photocatalytic activity of TiO2 powder was determined by the photodegradation of MB dye under UV light.

  8. A situ co-precipitation method to prepare magnetic PMDA modified sugarcane bagasse and its application for competitive adsorption of methylene blue and basic magenta.

    PubMed

    Yu, Jun-Xia; Chi, Ru-An; Zhang, Yue-Fei; Xu, Zhi-Gao; Xiao, Chun-Qiao; Guo, Jia

    2012-04-01

    Magnetic pyromellitic dianhydride (PMDA) modified sugarcane bagasse (SCB) was prepared by a situ co-precipitation method. Results showed that the magnetic modified SCB could be recycled easily by an applied magnetic field. Adsorption capacities of the magnetic sorbent for cationic dyes: methylene blue and basic magenta were 315.5 and 304.9mgg(-1), respectively. Competitive adsorption in the binary system showed that concentration percentages (C(P)) and initial concentration (C(0)) both had good linear relationship with adsorption capacities of the magnetic sorbent (q(e)(')) in the investigated range. The linear equations between C(P) and q(e)(') almost did not affect by the variation of total initial concentration of the dyes (C(T)), whereas that between C(0) and q(e)(') changed greatly with it. C(P) was the main factor that impacted q(e)(') in the binary competitive adsorption system. Similar linear equations between C(P) and q(e)(') demonstrated that the magnetic sorbent had similar adsorption affinity toward the two dyes.

  9. Fe{sub 3}O{sub 4}/Zeolite nanocomposites synthesized by microwave assisted coprecipitation and its performance in reducing viscosity of heavy oil

    SciTech Connect

    Iskandar, Ferry; Fitriani, Pipit; Merissa, Shanty; Khairurrijal,; Abdullah, Mikrajuddin; Mukti, Rino R.

    2014-02-24

    Fe{sub 3}O{sub 4}/Zeolite nanocomposites have been synthesized via microwave assisted coprecipitation method and show to be efficient in reducing viscosity of heavy oil compared to other Fe{sub 3}O{sub 4}/Zeolite nanocomposites prepared by conventional method. The following precursors such as FeCl{sub 3}⋅6H{sub 2}O, FeSO{sub 4}⋅7H{sub 2}O, NH{sub 4}OH, and natural zeolite of heulandite type were used in the sample preparation. In this study, the effect of Fe{sub 3}O{sub 4} composition in the composite and microwave time heating were investigated. Fe{sub 3}O{sub 4}/Zeolite nanocomposites were then characterized to study the influence on crystal structures, morphology and physicochemical properties. The characterization techniques include X-ray diffraction (XRD), scanning electron microscopy (SEM) and nitrogen physisorption. The results show that by increasing the microwave heating time, the degree of nanocomposite intergrowth can be enhanced. The nanocomposite was tested in catalytic aquathermolysis of heavy oil at 200°C for 6 h and the Fe{sub 3}O{sub 4}/zeolite of 1 to 4 ratios performed the highest viscosity reduction of heavy oil reaching 92%.

  10. Influence of pH on the formulation of TiO2 powder prepared by co-precipitation of TiCl3 and photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Yudoyono, Gatut; Zharvan, Vicran; Ichzan, Nur; Daniyati, Rizqa; Indarto, Bachtera; Pramono, Yono Hadi; Zainuri, Mochamad; Darminto

    2016-02-01

    Titanium dioxide (titania) nanoparticle were synthesized by coprecipitation process of titanium trichloride (TiCl3) in aqueous medium, with NH4OH as pH regulator. The pH solution was varied during the synthesis process between pH 3-8.4, and all samples were calcined temperature at 400°C for 3 hours. Characteristics and properties of the TiO2 powder were investigated using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM). XRD results show that the single-phase rutile formed when the pH is less than 5, anatase single phase formed began pH 8, and the pH of the solution between 5-8 formed mixed phase rutile-anatase-brookite, rutile-brookite or anatase-brookite. Methylene Blue (MB) photodegradation test were performed in order to evaluate photocatalytic activity. Nanoparticles TiO2 rutile, anatase phase, and mixed phase rutile-brookite, anatase-brookite used to test the photocatalytic activity by measuring the absorbance spectrum photodegradation using UV-Vis spectrometer. The test results showed that the mixture phase of rutile-brookite provide the greatest photodegradation than other phases.

  11. Co-precipitated and collocated carbides and Cu-rich precipitates in a Fe-Cu steel characterized by atom-probe tomography.

    PubMed

    Kolli, R Prakash; Seidman, David N

    2014-12-01

    The composition of co-precipitated and collocated NbC carbide precipitates, Fe3C iron carbide (cementite), and Cu-rich precipitates are studied experimentally by atom-probe tomography (APT). The Cu-rich precipitates located at a grain boundary (GB) are also studied. The APT results for the carbides are supplemented with computational thermodynamics predictions of composition at thermodynamic equilibrium. Two types of NbC carbide precipitates are distinguished based on their stoichiometric ratio and size. The Cu-rich precipitates at the periphery of the iron carbide and at the GB are larger than those distributed in the α-Fe (body-centered cubic) matrix, which is attributed to short-circuit diffusion of Cu along the GB. Manganese segregation is not observed at the heterophase interfaces of the Cu-rich precipitates that are located at the periphery of the iron carbide or at the GB, which is unlike those located at the edge of the NbC carbide precipitates or distributed in the α-Fe matrix. This suggests the presence of two populations of NiAl-type (B2 structure) phases at the heterophase interfaces in multicomponent Fe-Cu steels.

  12. Optimizing and modeling of effective parameters on the structural and magnetic properties of Fe3O4 nanoparticles synthesized by coprecipitation technique using response surface methodology

    NASA Astrophysics Data System (ADS)

    Ghazanfari, Mohammad Reza; Kashefi, Mehrdad; Jaafari, Mahmoud Reza

    2016-07-01

    In present work, the Fe3O4 magnetic nanoparticles were successfully synthesized by coprecipitation method. In order to study the effects of influential factors on the structural and magnetic properties of particles, the experimental runs were designed using response surface methodology (RSM) based on central composite design (CCD), while the reaction temperature, Fe2+/Fe3+ cation ratio, and pH of reaction were defined as effective factors on the two responses include the amounts of crystallinity degree and saturation magnetization (Ms). The investigation of structural, magnetic, and microstructural properties of particles were carried out by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and dynamic light scattering (DLS) and transmission electron microscopy (TEM) analyses. As a result, the predictive quadratic models were fitted on the both responses while the R2 values were more than 0.97 for both models. The highest amounts of both responses (crystallinity degree: 88.07% and Ms: 65.801 emu/g) are presented when the reaction temperature, cation ratio, and pH amounts are equal to 90 °C, 0.60, and 10.5, respectively. Finally, the TEM results show the particles with size of about 10 nm and narrow size distribution.

  13. Photoluminescence, photocatalytic and antibacterial activities of CeO2·CuO·ZnO nanocomposite fabricated by co-precipitation method.

    PubMed

    Subhan, Md Abdus; Uddin, Nizam; Sarker, Prosenjit; Azad, Abul Kalam; Begum, Kulsuma

    2015-10-01

    A novel tri-metallic oxide nanocomposite CeO2·CuO·ZnO has been synthesized by a simple co-precipitation method. The nanocomposite has been characterized by XRD, SEM, EDS, FTIR and PL spectra. The crystallite size of the CeO2·CuO·ZnO was calculated using XRD data. The crystallite size of the CeO2·CuO·ZnO mixed metal oxide annealed at 600 °C is found to be in range of 15.34-44.81 nm, with an average size of 29.51 nm. Excitation at different wavelengths showed PL in UV and visible regions. It has been found that PL behavior of CeO2·CuO·ZnO is excitation wavelength dependent. This flexible PL property is conflicting to well-known Kasha's rule of excitation wavelength dependence of emission spectrum. The catalyst shows better photo-catalytic dye degradation efficiency in slightly alkaline pH in presence of H2O2. Nanocomposite CeO2·CuO·ZnO was found to be effective against pathogenic bacteria. PMID:26002435

  14. Modeling and optimization of effective parameters on the size of synthesized Fe3O4 superparamagnetic nanoparticles by coprecipitation technique using response surface methodology

    NASA Astrophysics Data System (ADS)

    Ghazanfari, Mohammad Reza; Kashefi, Mehrdad; Jaafari, Mahmoud Reza

    2016-05-01

    Generally, the statistical methods are defined as appropriate techniques to study the processes trends. In current research, the Fe3O4 superparamagnetic nanoparticles were synthesized by coprecipitation method. In order to investigate the size properties of synthesized particles, the experimental design was done using central composite method (CCD) of response surface methodology (RSM) while the temperature, pH, and cation ratio of reaction were selected as influential factors. After particles synthesis based on designed runs, the different responses such as hydrodynamic size of particles (both freeze dried and air dried), size distribution, crystallite size, magnetic size, and zeta potential were evaluated by different techniques i.e. dynamic light scattering (DLS), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). Based on these results, the quadratic polynomial model was fitted for each response that could predict the response amounts. In following, the study of factors effects was carried out that showed the temperature, pH, and their interactions had higher effectiveness. Finally, by optimizing, it was clear that the minimum amounts of particle size (10.15 nm) and size distribution (13.01 nm) were reached in the minimum temperature (70 °C) and cation ratio (0.5) amounts and maximum pH amount (10.5). Moreover, the characterizations showed the particles size was about 10 nm while the amounts of Ms, Hc, and Mr were equal to 60 (emu/g), 0.2 (Oe) and 0.22 (emu/g), respectively.

  15. Novel Synthesis of Ultra-Small Dextran Coated Maghemite Nanoparticles for MRI and CT Contrast Agents via a Low Temperature Co-Precipitation Reaction.

    PubMed

    Rabias, Ioannis; Fardis, Michael; Kehagias, Thomas; Kletsas, Dimitris; Pratsinis, Harris; Tsitrouli, Danai; Maris, Thomas G; Papavassiliou, George

    2015-01-01

    Ultra-small dextran coated maghemite nanoparticles are synthesized via a low temperature modified co-precipitation method. A monoethylene glycol/water solution of 1:1 molar ratios and a fixed apparatus is used at a constant temperature of 5-10 degrees C. The growth of nanoparticles is prohibited due to low temperature synthesis and differs from usual thermal decomposition methods via Ostwald ripening. Strict temperature control and reaction timing of less than 20 minutes are essential to maintain narrow distribution in particle size. These nanoparticles are water-dispersible and biocompatible by capping with polyethylene glycol ligands. The aqueous suspensions are tested for cytotoxic activity on normal human skin fibroblasts. There is no reduction of the cells' viability at any concentration tested, the highest being 1% v/v of the suspension in culture medium, corresponding to the highest concentrations to be administered in vivo. Initial comparison with a T1 MRI contrast agent in sale shows that maghemite nanoparticles exhibit high r1 and r2 relaxivities in MRI tomography and strong contrast in computed tomography, demonstrating that these nanoparticles can be efficient T1, T2 and CT contrast agents. PMID:26328331

  16. The magnetic and oxidation behavior of bare and silica-coated iron oxide nanoparticles synthesized by reverse co-precipitation of ferrous ion (Fe2+) in ambient atmosphere

    NASA Astrophysics Data System (ADS)

    Mahmed, N.; Heczko, O.; Lancok, A.; Hannula, S.-P.

    2014-03-01

    The synthesis of iron oxide nanoparticles, i.e., magnetite was attempted by using only ferrous ion (Fe2+) as a magnetite precursor, under an ambient atmosphere. The room temperature reverse co-precipitation method was used, by applying two synthesis protocols. The freshly prepared iron oxide was also immediately coated with Stöber silica (SiO2) layer, forming the coreshell structure. The phase, stoichiometry, crystallite and the particle size of the synthesized powders were determined by using X-ray diffraction (XRD) and transmission electron microscope (TEM), while the magnetic and oxidation behaviors were studied by using the vibrating sample magnetometer (VSM) and Mössbauer spectroscopy. Based on the results, the bare iron oxide nanoparticles are in the stoichiometry between the magnetite and the maghemite stoichiometry, i.e., oxidation occurs. This oxidation is depending on the synthesis protocols used. With the silica coating, the oxidation can be prevented, as suggested by the fits of Mössbauer spectra and low temperature magnetic measurement.

  17. Enhanced UVB emission and analysis of chemical states of Ca5(PO4)3OH:Gd3+,Pr3+ phosphor prepared by co-precipitation

    NASA Astrophysics Data System (ADS)

    Mokoena, P. P.; Nagpure, I. M.; Kumar, Vinay; Kroon, R. E.; Olivier, E. J.; Neethling, J. H.; Swart, H. C.; Ntwaeaborwa, O. M.

    2014-08-01

    Hydroxyapatite (Ca5(PO4)3OH) is a well-known bioceramic material used in medical applications because of its ability to form direct chemical bonds with living tissues. This mineral is currently used as a host for rare-earth ions (e.g. Gd3+, Pr3+, Tb3+, etc.) to prepare phosphors that can be used in light emitting devices of different types. In this study Ca5(PO4)3OH:Gd3+,Pr3+ phosphors were prepared by the co-precipitation method and were characterised by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, high resolution transmission electron microscopy, energy dispersive x-ray spectroscopy and photoluminescence spectroscopy. The x-ray diffraction pattern was consistent with the hexagonal phase of Ca5(PO4)3OH referenced in JCPDS card number 73-0293. The x-ray photoelectron spectroscopy data indicated that Ca2+ occupied two different lattice sites, referred to as Ca1 and Ca2. The photoluminescence data exhibited a narrowband emission located at 313 nm, which is associated with the 6P7/2→8S7/2 transition of the Gd3+ ion. This emission is classified as ultraviolet B and it is suitable for use in phototherapy lamps to treat various skin diseases. The photoluminescence intensity of the 313 nm emission was enhanced considerably by Pr3+ co-doping.

  18. Investigation of the Role of Ce3+ Substituted Ions on Dielectric Properties of Co-Cr Ferrites Prepared by Co-precipitation Method

    NASA Astrophysics Data System (ADS)

    Mustafa, Ghulam; Islam, M. U.; Zhang, Wenli; Arshad, M. I.; Jamil, Yasir; Anwar, Hafeez; Murtaza, G.; Hussain, Mudassar; Ahmad, Mukhtar

    2016-11-01

    A series of a CoCr0.04Ce x Fe1.96- x O4 spinel ferrite system with 0 ≤ x ≤ 0.1 (in steps of 0.02) has been synthesized by the co-precipitation technique. The synthesized samples were characterized using a Fourier transform infrared spectroscope (FT-IR), Raman spectroscopy, a scanning electron microscope (SEM), and dielectric measurements. The typical FT-IR spectrum of the samples annealed at 850°C exhibited two frequency bands due to the formation of octahedral (B-site) and tetrahedral (A-site) clusters of metal oxide, respectively. The SEM images showed the spherical morphology of synthesized material and confirmed the grain size in the range of (0.33-0.44) μm. The decrease of permittivity with the increase of frequency in the range of 1 MHz to 3 GHz follows the Maxwell-Wagner model. Moreover, the Ce3+substituted materials have smaller values of loss tangent and dielectric constant especially for x = 0.10, which is favorable for the applications where low losses are desired. The value of ac (alternating current) conductivity increases with an increase in the frequency and decreases with Ce3+ substitution, which reflects the hopping mechanism at respective sites. Such characteristics of these materials may be suitable for potential applications such as electromagnetic attenuation materials, switching applications, and microwave devices.

  19. Structure and photoluminescence studies of CeO2·CuAlO2 mixed metal oxide fabricated by co-precipitation method

    NASA Astrophysics Data System (ADS)

    Subhan, Md Abdus; Ahmed, Tanzir; Awal, M. R.; Kim, B. Moon

    2015-01-01

    A novel mixed metal oxide, CeO2·CuAlO2 was fabricated by co-precipitation method in aqueous medium. CeO2·CuAlO2 was characterized by XRD, SEM, EDS, TEM, FTIR and PL spectra. The optical properties of the nanoparticles were studied by photoluminescence (PL) spectra. PL spectra at different excitations were recorded. The composite showed emission in UV, visible and NIR region depending on the excitation wavelength. The special spectral feature observed for this composite is that it showed six emission bands at 364, 409, 434, 448, 465 and 481 nm when excited at 298 nm. The green and red emissions observed at 512 and 669 nm are originated from cubic CeO2 phase when excited at 450 nm. The PL spectra were found to be dependent on excitation wavelength violating Kasha's rule. The X-ray diffraction reveals a cubic CeO2 phase and hexagonal CuAlO2 phase. EDS spectra revealed the presence of cerium (Ce), copper (Cu), aluminum (Al) and oxygen (O) elements. The particle size of the CeO2·CuAlO2 mixed oxide was estimated using Scherrer's formula, which was found to be in the range of 17.2-34.2 nm. The TEM image showed particles are almost uniform size of approximately 15-50 nm with spherical morphology.

  20. Structure and photoluminescence studies of CeO2·CuAlO2 mixed metal oxide fabricated by co-precipitation method.

    PubMed

    Subhan, Md Abdus; Ahmed, Tanzir; Awal, M R; Kim, B Moon

    2015-01-25

    A novel mixed metal oxide, CeO2·CuAlO2 was fabricated by co-precipitation method in aqueous medium. CeO2·CuAlO2 was characterized by XRD, SEM, EDS, TEM, FTIR and PL spectra. The optical properties of the nanoparticles were studied by photoluminescence (PL) spectra. PL spectra at different excitations were recorded. The composite showed emission in UV, visible and NIR region depending on the excitation wavelength. The special spectral feature observed for this composite is that it showed six emission bands at 364, 409, 434, 448, 465 and 481 nm when excited at 298 nm. The green and red emissions observed at 512 and 669 nm are originated from cubic CeO2 phase when excited at 450 nm. The PL spectra were found to be dependent on excitation wavelength violating Kasha's rule. The X-ray diffraction reveals a cubic CeO2 phase and hexagonal CuAlO2 phase. EDS spectra revealed the presence of cerium (Ce), copper (Cu), aluminum (Al) and oxygen (O) elements. The particle size of the CeO2·CuAlO2 mixed oxide was estimated using Scherrer's formula, which was found to be in the range of 17.2-34.2 nm. The TEM image showed particles are almost uniform size of approximately 15-50 nm with spherical morphology. PMID:25113734

  1. Solid state and magnetochemistry of the SrO-Fe2O3 system IV. Synthesis of SrFe12O19 from coprecipitated precursors

    NASA Astrophysics Data System (ADS)

    Qian, Xueyu; Evans, B. J.

    1981-03-01

    By means of 57Fe Mössbauer spectroscopy and powder x-ray diffraction techniques, it has been determined that the formation of SrFe12O19 from coprecipitated ferric hydroxide and strontium laurate follows a reaction mechanism different from that when SrCO3 and Fe2O3 are used as starting materials. Upon heating at 300 C in vacuum, strontium laurate decomposes and further heating to 550 C leads to the formation of γ-Fe2O3 from the ferric hydroxide and solid solution of SrO in γ-Fe2O3. This solid solution phase behaves as an intermediate and undergoes further reaction with γ-Fe2O3 to give SrFe12O19. No paramagnetic Sr-Fe oxide intermediate is formed. The low temperature of the reactions and the absence of paramagnetic intermediates offer new possibilities for controlling the textures and magnetic properties SrFe12O19 ceramic bodies.

  2. Investigation of structural and magnetic properties of co-precipitated Mn-Ni ferrite nanoparticles in the presence of α-Fe2O3 phase

    NASA Astrophysics Data System (ADS)

    Tirupanyam, B. V.; Srinivas, Ch.; Meena, S. S.; Yusuf, S. M.; Satish Kumar, A.; Sastry, D. L.; Seshubai, V.

    2015-10-01

    A systematic study on structural and magnetic properties of co-precipitated MnxNi1-xFe2O4 (x=0.5, 0.6, 0.7) ferrite nanoparticles annealed at 800 °C was carried out using XRD, FE-SEM, VSM and MÖSSBAUER techniques. Anti-ferromagnetic α-Fe2O3 phase was observed along with the magnetic spinel phase in the XRD patterns. It is observed that both lattice parameter and crystallite size of spinel phase increase with increase in concentration of Mn2+ along with the amount of α-Fe2O3 phase. The saturation magnetization (Ms) decreases while coercivity (Hc) increases with increase of Mn2+ ion concentration. Mössbauer spectra indicate that iron ions present in A and B sites are in the Fe3+ state and Fe2+ is absent. The results are interpreted in terms of observed anti-ferromagnetic α-Fe2O3 phase, core-shell interactions and cation redistribution.

  3. Controllable synthesis of spinel lithium nickel manganese oxide cathode material with enhanced electrochemical performances through a modified oxalate co-precipitation method

    NASA Astrophysics Data System (ADS)

    Liu, Hongmei; Zhu, Guobin; Zhang, Li; Qu, Qunting; Shen, Ming; Zheng, Honghe

    2015-01-01

    A spinel lithium nickel manganese oxide (LiNi0.5Mn1.5O4) cathode material is synthesized with a modified oxalate co-precipitation method by controlling pH value of the precursor solution and introducing excessive Li source in the precursor. All the samples synthesized through this method are of Fd3m phase with a small amount of P4332 phase. It is found that pH value of the precursor solution considerably affects the morphology, stoichiometry and crystallographic structure of the target material, thereby resulting in different amounts of Mn3+ (i.e., different degree of disorder). 5% excessive Li source in the precursor may compensate for the lithium loss during the high-temperature sintering process and eliminate the LixNi1-xO impurity phase. Under the optimized synthesis conditions, the obtained high-purity LiNi0.5Mn1.5O4 spinel exhibits enhanced electrochemical performances. A reversible capacity of ca. 140 mAh g-1 can be delivered at 0.1C and the electrode retains 106 mAh g-1 at 10C rate. When cycled at 0.2C, a capacity retention of more than 98% is obtained in the initial 50 electrochemical cycles.

  4. A co-precipitation preparation, crystal structure and photoluminescent properties of Er5%:Gd{sub 2}O{sub 3} nanorods

    SciTech Connect

    Boopathi, G. Mohan, R.; Raj, S. Gokul; Kumar, G. Ramesh

    2015-06-24

    An inexpensive preparation method is being reported for obtaining erbium doped gadolinium oxide (Er5%:Gd{sub 2}O{sub 3}) nanoscale rods. The elongated nanoscale systems, as-formed through a co-precipitation process, are characterized by using X-ray powder diffraction (XRD) patterns, scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) mapping, Ultra Violet-visible (UV-vis.) absorption spectroscopy and photoluminescence (PL) spectroscopy. In addition, the Williamson–Hall (W–H) plot is also performed to distinguish the effect of crystalline size-induced broadening and strain-induced broadening at full-width at half-maximum (FWHM) of the XRD profile. The XRD patterns of as-formed and calcined products show that the phase confirmation. As revealed from the SEM micrographs, the morphology of the products show that the rod-like nanoparticles. The EDX micrographs show that the presence of elements in our samples. The band gap values in calcined samples are found to be in the range of 3.569 eV. Upon 230 nm excitation on calcined samples, three broad emission peaks are observed from PL studies. The possible mechanism for the formation of Er5%:Gd{sub 2}O{sub 3} nanorods is briefly discussed.

  5. Fe(II)-Al(III) layered double hydroxides prepared by ultrasound-assisted co-precipitation method for the reduction of bromate.

    PubMed

    Zhong, Yu; Yang, Qi; Luo, Kun; Wu, Xiuqiong; Li, Xiaoming; Liu, Yang; Tang, Wangwang; Zeng, Guangming; Peng, Bo

    2013-04-15

    Bromate is recognized as an oxyhalide disinfection byproduct in drinking water. In this paper, Fe(II)-Al(III) layered double hydroxides (Fe-Al LDHs) prepared by the ultrasound-assisted co-precipitation method were used for the reduction of bromate in solution. The Fe-Al LDHs particles were characterized by X-ray diffractometer, scanning electron microscopy and thermogravimetry-differential scanning calorimetry. It was found that ultrasound irradiation assistance promoted the formation of the hydrotalcite-like phase and then improved the removal efficiency of bromate. In addition, the effects of solid-to-solution ratio, contact time, initial bromate concentration, initial pH, coexisting anions on the bromate removal were investigated. The results showed the bromate with an initial concentration of 1.56 μmol/L could be completely removed from solution by Fe-Al LDHs within 120 min. When the initial bromate concentration was 7.81 μmol/L, the Fe-Al LDHs with irradiation time of 30 min exhibited the optimum removal efficiency and the bromate removal capacity (qe) was 6.80 μmol/g. In addition, the appearance of sulfate and production of bromide were observed simultaneously in this process, which suggested that ion-exchange between sulfate and bromate, and the reduction of bromate to bromide by Fe(2+) were the main mechanisms responsible for the bromate removal by Fe-Al LDHs.

  6. Speciation of Cr(III) and Cr(VI) in geological and water samples by ytterbium(III) hydroxide coprecipitation system and atomic absorption spectrometry.

    PubMed

    Duran, Ali; Tuzen, Mustafa; Soylak, Mustafa

    2011-07-01

    A novel coprecipitation method with ytterbium(III) hydroxide has been established for speciation of Cr(III) and Cr(VI) in geological and water samples. At pH 10, while Cr(III) was quantitatively recovered, Cr(VI) was recovered under 10% levels. Total chromium was determined reducing of Cr(VI) to Cr(III) in acidic media with KI reagent. The concentration of Cr(VI) was calculated by the concentration difference between the total chromium and Cr(III). For the quantitative recovery of Cr(III), parameters such as pH, amount of ytterbium, centrifugation time and speed, matrix effect, KI amount, and sample volume were investigated. The preconcentration factor was 30. The limit of detection was obtained as 1.1 μg/L for Cr(III). The accuracy was checked by analyte addition and analyses of standard reference materials (TMDA-54.4 Certified Reference Water, NIST 2710 Montana Soil). Method has been successfully applied to the chromium speciation for industrial waste water of leather factories located in Bor-Nigde, and also for mine and soil samples.

  7. Determination of the platinum - Group elements (PGE) and gold (Au) in manganese nodule reference samples by nickel sulfide fire-assay and Te coprecipitation with ICP-MS

    USGS Publications Warehouse

    Balaram, V.; Mathur, R.; Banakar, V.K.; Hein, J.R.; Rao, C.R.M.; Gnaneswara, Rao T.; Dasaram, B.

    2006-01-01

    Platinum group elements (PGE) and Au data in polymetallic oceanic ferromanganese nodule reference samples and crust samples obtained by inductively coupled plasma mass spectrometry (ICP-MS), after separation and pre-concentration by nickel sulfide fire-assay and Te coprecipitation, are presented. By optimizing several critical parameters such as flux composition, matrix matching calibration, etc., best experimental conditions were established to develop a method suitable for routine analysis of manganese nodule samples for PGE and Au. Calibrations were performed using international PGE reference materials, WMG-1 and WMS-1. This improved procedure offers extremely low detection limits in the range of 0.004 to 0.016 ng/g. The results obtained in this study for the reference materials compare well with previously published data wherever available. New PGE data arc also provided on some international manganese nodule reference materials. The analytical methodology described here can be used for the routine analysis of manganese nodule and crust samples in marine geochemical studies.

  8. Synthesis of well-dispersed magnetic CoFe2O4 nanoparticles in cellulose aerogels via a facile oxidative co-precipitation method.

    PubMed

    Wan, Caichao; Li, Jian

    2015-12-10

    With the increasing emphasis on green chemistry, it is becoming more important to develop environmentally friendly matrix materials for the synthesis of nanocomposites. Cellulose aerogels with hierarchical micro/nano-scale three-dimensional network beneficial to control and guide the growth of nanoparticles, are suitable as a class of ideal green nanoparticles hosts to fabricate multifunctional nanocomposites. Herein, a facile oxidative co-precipitation method was carried out to disperse CoFe2O4 nanoparticles in the cellulose aerogels matrixes, and the cellulose aerogels were prepared from the native wheat straw based on a green NaOH/polyethylene glycol solution. The mean diameter of the well-dispersed CoFe2O4 nanoparticles in the hybrid aerogels is 98.5 nm. Besides, the hybrid aerogels exhibit strong magnetic responsiveness, which could be flexibly actuated by a small magnet. And this feature also makes this class of magnetic aerogels possibly useful as recyclable adsorbents and some magnetic devices. Meanwhile, the mild green preparation method could also be extended to fabricate other miscellaneous cellulose-based nanocomposites.

  9. Synthesis, structural and optical properties of pure ZnO and Co doped ZnO nanoparticles prepared by the co-precipitation method

    NASA Astrophysics Data System (ADS)

    Devi, P. Geetha; Velu, A. Sakthi

    2016-09-01

    Pure ZnO and Cobalt (Co) doped ZnO nanoparticles (NPs) were synthesized by the co-precipitation method. The synthesized nanoparticles retained the wurtzite hexagonal structure, which was confirmed by X-ray diffraction studies. From FESEM studies, ZnO and Co doped ZnO NPs showed Spherical and nanorod mixed phase and Spherical like morphology, respectively. The amount of dopant (Co2+) incorporated into ZnO sample was determined by EDAX. The FT-IR spectra confirmed the Zn-O stretching bands at 438 and 427 cm-1 for ZnO and Co doped ZnO NPs. From the UV-VIS spectroscopic measurements, the excitonic pecks were found around 376 and 370 nm for the respective samples. The photoluminescence measurements revealed that the broad emission was composed of seven different bands due to zinc vacancies, oxygen vacancies and surface defects. The dynamic light scattering (DLS) and Zeta potential measurements were used to find out the size and surface charges.

  10. Improved emission of Eu3+ by energy transfer via Tb3+ in coprecipitates TbxEu(1-x)(aspirin)3(phen)

    NASA Astrophysics Data System (ADS)

    Zhang, T.; Xu, Z.; Qian, L.; Teng, F.; Xu, X. R.; Tao, D. L.

    2005-09-01

    In order to increase the red emission of Eu complex doped in poly(N-vinylcarbazole) (PVK), series of molar ratio coprecipitates [TbxEu(1-x)(aspirin)3(phen).H2O] (phen=1,10-phenanthroline) were prepared, in which Tb3+ ion acts as an energy bridge to enhance the energy transfer between the ligands and europium ion. The intramolecular energy transfer from Tb3+ to Eu3+ was studied via a time-resolved spectrum. It gave a direct evidence of the intramolecular energy transfer between the two lanthanide ions of terbium and europium. The photoluminescence and electroluminescence spectra as well as the performance of the device indium tin oxide/poly-(3,4-ethylenedioxythiophene):poly-(styrenesulphonic acid)/PVK:TbxEu(1-x)(aspirin)3(phen)/Al were also studied. Compared with that of PVK:Eu(aspirin)3phen device, the result showed an enhanced emission of Eu3+ ion due to the energy transfer via Tb3+ ion.

  11. Mesoporous composite nickel cobalt oxide/graphene oxide synthesized via a template-assistant co-precipitation route as electrode material for supercapacitors

    NASA Astrophysics Data System (ADS)

    Xu, Yanjie; Wang, Lincai; Cao, Peiqi; Cai, Chuanlin; Fu, Yanbao; Ma, Xiaohua

    2016-02-01

    A simple co-precipitation method utilizing SDS (sodium dodecyl sulfate) as template and ammonia as precipitant is successfully employed to synthesize nickel cobalt oxide/graphene oxide (NiCo2O4/GO) composite. The as-prepared composite (NCG-10) exhibits a high capacitance of 1211.25 F g-1, 687 F g-1 at the current density of 1 A g-1, 10 A g-1 and good cycling ability which renders NCG-10 as promising electrode material for supercapacitors. An asymmetric supercapacitor (ASC) (full button cell) has been constructed with NCG-10 as positive electrode and lab-made reduced graphene oxide (rGO) as negative electrode. The fabricated NCG-10//rGO with an extended stable operational voltage of 1.6 V can deliver a high specific capacitance of 144.45 F g-1 at a current density of 1 A g-1. The as-prepared NCG-10//rGO demonstrates remarkable energy density (51.36 W h kg-1 at 1 A g-1), high power density (50 kW kg-1 at 20 A g-1). The retention of capacitance is 88.6% at the current density of 8 A g-1 after 2000 cycles. The enhanced capacitive performance can be attributed to the improved specific surface area and 3D open area of NCG-10 generated by the pores and channels with the substantial function of SDS.

  12. Suppressed carrier full-spectrum combining

    NASA Technical Reports Server (NTRS)

    Rogstad, D. H.

    1991-01-01

    A technique to accomplish full spectrum arraying where all the telemetry power is put into the subcarrier sidebands (suppressed carrier) is described. The matched filter needed in each antenna prior to cross correlation for deriving the coherence delay and phase offsets is an open loop version of the telemetry phase lock loop provided in the Advanced Digital Receiver. In analogy with a Costas loop telemetry receiver, a squaring loss is derived, and a signal to noise ratio for the cross correlation loop phase is presented.

  13. Suppressed carrier full-spectrum combining

    NASA Astrophysics Data System (ADS)

    Rogstad, D. H.

    1991-11-01

    A technique to accomplish full spectrum arraying where all the telemetry power is put into the subcarrier sidebands (suppressed carrier) is described. The matched filter needed in each antenna prior to cross correlation for deriving the coherence delay and phase offsets is an open loop version of the telemetry phase lock loop provided in the Advanced Digital Receiver. In analogy with a Costas loop telemetry receiver, a squaring loss is derived, and a signal to noise ratio for the cross correlation loop phase is presented.

  14. 77 FR 60507 - Motor Carrier Safety Advisory Committee (MCSAC): Public Subcommittee Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-03

    ... Federal Motor Carrier Safety Administration Motor Carrier Safety Advisory Committee (MCSAC): Public Subcommittee Meeting AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT. ACTION: Notice of Meeting of Compliance, Safety, Accountability (CSA) Subcommittee of Motor Carrier Safety...

  15. 78 FR 5243 - Motor Carrier Safety Advisory Committee (MCSAC): Public Meeting of Subcommittees

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-24

    ... Federal Motor Carrier Safety Administration Motor Carrier Safety Advisory Committee (MCSAC): Public Meeting of Subcommittees AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT. ACTION: Notice of meeting of Motor Carrier Safety Advisory Committee (MCSAC). SUMMARY: FMCSA announces that...

  16. Coprecipitation and hydrothermal synthesis of ultrafine 5.5 mol% CeO{sub 2}-2 mol% YO{sub 1.5}-ZrO{sub 2} powders

    SciTech Connect

    Lin, J.D.; Duh, J.G.

    1997-01-01

    Ultrafine 5.5 mol% CeO{sub 2}-2 mol% YO{sub 1.5}-ZrO{sub 2} powders with controllable crystallite size were synthesized by two kinds of coprecipitation methods and subsequent crystallization treatment. The amorphous gel produced by ammonia coprecipitation and hydrothermal treatment at 200 C for 3.5 h results in an ultrafine powder with a surface area of 206 m{sup 2}/g and a crystallite size of 4.8 nm. The powder produced by urea hydrolysis and calcination exhibits a purely tetragonal phase. In addition, the powders crystallized by hydrothermal treatment exhibit high packing density and can be sintered at lower temperature (<1,400 C) with nearly 100% tetragonal phase achieved.

  17. Residual and suppressed-carrier arraying techniques for deep-space communications

    NASA Technical Reports Server (NTRS)

    Shihabi, M.; Shah, B.; Hinedi, S.; Million, S.

    1995-01-01

    Three techniques that use carrier information from multiple antennas to enhance carrier acquisition and tracking are presented. These techniques in combination with baseband combining are analyzed and simulated for residual and suppressed-carrier modulation. It is shown that the carrier arraying using a single carrier loop technique can acquire and track the carrier even when any single antenna in the array cannot do so by itself. The carrier aiding and carrier arraying using multiple carrier loop techniques, on the other hand, are shown to lock on the carrier only when one of the array elements has sufficient margin to acquire the carrier on its own.

  18. Colloidal carrier systems for transcutaneous immunization.

    PubMed

    Gupta, Prem N; Vyas, Suresh P

    2011-04-01

    Recently, the skin has emerged as a potential alternative route for non-invasive delivery of vaccine. It has been recognized as a highly immune-reactive tissue containing an abundance of antigen presenting cells, especially within the epidermis. Transcutaneous immunization, introduction of antigen through topical application onto the intact skin, has many practical merits compared to injectable routes of administration. It combines the advantages of needle-free delivery while targeting the immunologically rich milieu of the skin. This simple and non-invasive immunization procedure elicits systemic and cell mediated immune responses and therefore, it provides a viable and cost-effective strategy for disease prevention. Various strategies i.e physical, chemical and novel carrier systems can be explored for trancutaneous immunization. Specially designed vaccine carrier systems are attracting immense attention and these could be potential module for non-invasive antigen delivery. The review covers topical delivery consideration in brief followed by an insight into various novel delivery systems for transcutaneous vaccine delivery.

  19. Carbon phosphide monolayers with superior carrier mobility.

    PubMed

    Wang, Gaoxue; Pandey, Ravindra; Karna, Shashi P

    2016-04-28

    Two dimensional (2D) materials with a finite band gap and high carrier mobility are sought after materials from both fundamental and technological perspectives. In this paper, we present the results based on the particle swarm optimization method and density functional theory which predict three geometrically different phases of the carbon phosphide (CP) monolayer consisting of sp2 hybridized C atoms and sp3 hybridized P atoms in hexagonal networks. Two of the phases, referred to as α-CP and β-CP with puckered or buckled surfaces are semiconducting with highly anisotropic electronic and mechanical properties. More remarkably, they have the lightest electrons and holes among the known 2D semiconductors, yielding superior carrier mobility. The γ-CP has a distorted hexagonal network and exhibits a semi-metallic behavior with Dirac cones. These theoretical findings suggest that the binary CP monolayer is a yet unexplored 2D material holding great promise for applications in high-performance electronics and optoelectronics. PMID:27067002

  20. Pathways to hydrogen as an energy carrier.

    PubMed

    Sigfusson, Thorsteinn I

    2007-04-15

    When hydrogen is used as an alternative energy carrier, it is very important to understand the pathway from the primary energy source to the final use of the carrier. This involves, for example, the understanding of greenhouse gas emissions associated with the production of hydrogen and throughout the lifecycle of a given utilization pathway as well as various energy or exergy efficiencies and aspects involved. This paper which is based on a talk given at the Royal Society in London assesses and reviews the various production pathways for hydrogen with emphasis on emissions, energy use and energy efficiency. The paper also views some aspects of the breaking of the water molecule and examines some new emerging physical evidence which could pave the way to a new and more feasible pathway. A special attention will be given to the use of the renewable energy pathway. As an example of a hydrogen society that could be based on renewable primary energy, the paper describes the hydrogen society experiments in Iceland as well as unconventional hydrogen obtained from geothermal gases. In the light of our experience, attempts will be made to shed light upon drivers as well as obstacles in the development of a hydrogen society.

  1. Localized charge carriers in graphene nanodevices

    SciTech Connect

    Bischoff, D. Varlet, A.; Simonet, P.; Eich, M.; Overweg, H. C.; Ihn, T.; Ensslin, K.

    2015-09-15

    Graphene—two-dimensional carbon—is a material with unique mechanical, optical, chemical, and electronic properties. Its use in a wide range of applications was therefore suggested. From an electronic point of view, nanostructured graphene is of great interest due to the potential opening of a band gap, applications in quantum devices, and investigations of physical phenomena. Narrow graphene stripes called “nanoribbons” show clearly different electronical transport properties than micron-sized graphene devices. The conductivity is generally reduced and around the charge neutrality point, the conductance is nearly completely suppressed. While various mechanisms can lead to this observed suppression of conductance, disordered edges resulting in localized charge carriers are likely the main cause in a large number of experiments. Localized charge carriers manifest themselves in transport experiments by the appearance of Coulomb blockade diamonds. This review focuses on the mechanisms responsible for this charge localization, on interpreting the transport details, and on discussing the consequences for physics and applications. Effects such as multiple coupled sites of localized charge, cotunneling processes, and excited states are discussed. Also, different geometries of quantum devices are compared. Finally, an outlook is provided, where open questions are addressed.

  2. Localized charge carriers in graphene nanodevices

    NASA Astrophysics Data System (ADS)

    Bischoff, D.; Varlet, A.; Simonet, P.; Eich, M.; Overweg, H. C.; Ihn, T.; Ensslin, K.

    2015-09-01

    Graphene—two-dimensional carbon—is a material with unique mechanical, optical, chemical, and electronic properties. Its use in a wide range of applications was therefore suggested. From an electronic point of view, nanostructured graphene is of great interest due to the potential opening of a band gap, applications in quantum devices, and investigations of physical phenomena. Narrow graphene stripes called "nanoribbons" show clearly different electronical transport properties than micron-sized graphene devices. The conductivity is generally reduced and around the charge neutrality point, the conductance is nearly completely suppressed. While various mechanisms can lead to this observed suppression of conductance, disordered edges resulting in localized charge carriers are likely the main cause in a large number of experiments. Localized charge carriers manifest themselves in transport experiments by the appearance of Coulomb blockade diamonds. This review focuses on the mechanisms responsible for this charge localization, on interpreting the transport details, and on discussing the consequences for physics and applications. Effects such as multiple coupled sites of localized charge, cotunneling processes, and excited states are discussed. Also, different geometries of quantum devices are compared. Finally, an outlook is provided, where open questions are addressed.

  3. Influence of carrier on the performance of dry powder inhalers.

    PubMed

    Saint-Lorant, G; Leterme, P; Gayot, A; Flament, M P

    2007-04-01

    The aim of this work is to study carriers which can become alternatives to monohydrate lactose in dry powder inhalers and to consider particle parameters that influence adhesion between drug and carrier in dry powder inhalers. Different forms of mannitol, lactose and maltitol were mixed with either terbutaline sulphate or formoterol fumarate. The blends were submitted to different adhesion tests where drug detachment from the carrier was obtained either through mechanical vibration or by aspiration. Parameters like particle shape, roughness, amorphous content and cristalline form may affect interactions between drug and carrier. In our case, crystallized forms of the carrier offered lower adhesion but better release of the active ingredient than spray-dried forms. The crystallized mannitol produced maximal fine particle dose. The blends of the mannitols and the two active ingredients gave different results. The two techniques used to assess the adhesion of drugs to carrier particles provide complementary information about drug/carrier interactions and detachment. The mechanical sieving allows to assess blend stability and the air-jet sieving makes it possible to determine how easily the drug separates from carrier. For the drugs tested, the results of fine particle doses are in agreement with the Alpine air-jet sieve results. The tests used are helpful for the choice of a new carrier in the field of the development of new carriers for dry powder inhalers. PMID:17113733

  4. Synthesis of Lix[Ni0.225Co0.125Mn0.65]O2 as a positive electrode for lithium-ion batteries by optimizing its synthesis conditions via a hydroxide co-precipitation method

    NASA Astrophysics Data System (ADS)

    Jeon, Hyo-Jin; Monim, Syed Abdul; Kang, Chung-Soo; Son, Jong-Tae

    2013-09-01

    Lix[Ni0.225Co0.125Mn0.65]O2 cathode material for a lithium-ion battery was synthesized from metal hydroxide Ni0.225Co0.125Mn0.65(OH)2. The co-precipitated metal hydroxide was greatly influenced by synthesis conditions of pH, concentration of chelating agent, stirring speed, and co-precipitation temperature. The conditions were optimized by observing the spherical and uniform particles, as examined by scanning electron microscopy. The optimized pH, ammonia concentration stirring speed and co-precipitation temperature were determined to be 11-12, 0.36 M, 1000 rpm and 50 °C, respectively. The final products, Lix[Ni0.225Co0.125Mn0.65]O2 had a well-ordered hexagonal super lattice layered structure as established by Rietveld refinement of X-ray diffraction pattern. As a result, the Lix[Ni0.225Co0.125Mn0.65]O2 compound may be considered as a excellent candidate for cathode material of Lithium secondary battery in terms of cycle life, both safety and energy density, lower cost and low environmental impact.

  5. Charge-carrier relaxation dynamics in highly ordered poly( p -phenylene vinylene): Effects of carrier bimolecular recombination and trapping

    NASA Astrophysics Data System (ADS)

    Soci, Cesare; Moses, Daniel; Xu, Qing-Hua; Heeger, Alan J.

    2005-12-01

    We have studied the charge-carrier relaxation dynamics in highly ordered poly( p -phenylene vinylene) over a broad time range using fast (t>100ps) transient photoconductivity measurements. The carrier density was also monitored (t>100fs) by means of photoinduced absorption probed at the infrared active vibrational modes. We find that promptly upon charge-carrier photogeneration, the initial polaron dynamics is governed by bimolecular recombination, while later in the subnanosecond time regime carrier trapping gives rise to an exponential decay of the photocurrent. The more sensitive transient photocurrent measurements indicate that in the low excitation regime, when the density of photocarriers is comparable to that of the trapping states (˜1016cm-3) , carrier hopping between traps along with transport via extended states determines the carrier relaxation, a mechanism that is manifested by a long-lived photocurrent “tail.” This photocurrent tail is reduced by lowering the temperature and/or by increasing the excitation density. Based on these data, we develop a comprehensive kinetic model that takes into account the bipolar charge transport, the free-carrier bimolecular recombination, the carrier trapping, and the carrier recombination involving free and trapped carriers.

  6. The effect of uniaxial strain on graphene nanoribbon carrier statistic.

    PubMed

    Johari, Zaharah; Ismail, Razali

    2013-01-01

    : Armchair graphene nanoribbon (AGNR) for n=3m and n=3m+1 family carrier statistic under uniaxial strain is studied by means of an analytical model based on tight binding approximation. The uniaxial strain of AGNR carrier statistic models includes the density of state, carrier concentration, and carrier velocity. From the simulation, it is found that AGNR carrier concentration has not been influenced by the uniaxial strain at low normalized Fermi energy for n=3m and n=3m+1. In addition, the carrier velocity of AGNR is mostly affected by strain at high concentration of n≈3.0×107 and 1.0 × 107 m-1 for n=3m and n=3m+1, respectively. The result obtained gives physical insight into the understanding of uniaxial strain in AGNR.

  7. Carrier tracking by smoothing filter improves symbol SNR

    NASA Technical Reports Server (NTRS)

    Pomalaza-Raez, Carlos A.; Hurd, William J.

    1986-01-01

    The potential benefit of using a smoothing filter to estimate carrier phase over use of phase locked loops (PLL) is determined. Numerical results are presented for the performance of three possible configurations of the deep space network advanced receiver. These are residual carrier PLL, sideband aided residual carrier PLL, and finally sideband aiding with a Kalman smoother. The average symbol signal to noise ratio (SNR) after losses due to carrier phase estimation error is computed for different total power SNRs, symbol rates and symbol SNRs. It is found that smoothing is most beneficial for low symbol SNRs and low symbol rates. Smoothing gains up to 0.4 dB over a sideband aided residual carrier PLL, and the combined benefit of smoothing and sideband aiding relative to a residual carrier loop is often in excess of 1 dB.

  8. Carrier tracking by smoothing filter can improve symbol SNR

    NASA Technical Reports Server (NTRS)

    Hurd, W. J.; Pomalaza-Raez, C. A.

    1985-01-01

    The potential benefit of using a smoothing filter to estimate carrier phase over use of phase locked loops (PLL) is determined. Numerical results are presented for the performance of three possible configurations of the deep space network advanced receiver. These are residual carrier PLL, sideband aided residual carrier PLL, and finally sideband aiding with a Kalman smoother. The average symbol signal to noise ratio (CNR) after losses due to carrier phase estimation error is computed for different total power SNRs, symbol rates and symbol SNRs. It is found that smoothing is most beneficial for low symbol SNRs and low symbol rates. Smoothing gains up to 0.4 dB over a sideband aided residual carrier PLL, and the combined benefit of smoothing and sideband aiding relative to a residual carrier loop is often in excess of 1 dB.

  9. Characteristics of participants in a gestational carrier program.

    PubMed

    Braverman, A M; Corson, S L

    1992-08-01

    Genetic parents and gestational carriers in our gestational carrier program were evaluated by psychodiagnostic interview and by the Minnesota Multiphasic Personality Interview-2 (MMPI-2), a widely used objective psychological test, to identify psychopathology and describe personality characteristics. Overall, participants exhibited no overt psychopathology. Personality differences were found between gestational carriers and genetic mothers and genetic fathers and mothers. Clinical interviews revealed that gestational carriers tended to be the dominant partner in the relationship, were motivated by a wish to help an infertile couple, enjoyed being pregnant, showed narcissistic needs, and expressed a wish for secondary financial gain. The majority of gestational carriers stated that they had considered becoming a traditional surrogate but felt they could not surrender a child that was genetically theirs. These results indicate that there is not any predisposing psychopathology which attracts participants to the gestational carrier program.

  10. The Group A Streptococcal Carrier State Reviewed: Still an Enigma.

    PubMed

    DeMuri, Gregory P; Wald, Ellen R

    2014-12-01

    Despite the common nature of group A streptococcal (GAS) infections, the carrier state of this organism is not well understood. In this article, we review the historical and recent research on the definition, epidemiology, and pathogenesis of the GAS carrier state. In addition, we outline trials of antimicrobial agents in the eradication of the carrier state and discuss indications for providing treatment to patients in the clinical setting. PMID:26625454

  11. Preparing concentrated carrier-free /sup 228/Ra

    SciTech Connect

    Volynskii, L.D.; Garbuzov, V.M.; Tsirlin, V.A.

    1988-05-01

    A scheme has been devised for processing large amounts of old thorium salts to obtain concentrated carrier-free /sup 228/Ra preparations. The process includes simple regeneration of the original thorium salt. The main stages in concentrating the /sup 228/Ra are precipitation and separation of thorium peroxide, isolating the radium with a carrier, ion-exchange separation of the radium from the carrier, and final purification by electrolysis. The /sup 228/Ra recovery is 70%.

  12. Resonant tunneling of carriers in silicon nanocrystals

    NASA Astrophysics Data System (ADS)

    Derbenyova, N. V.; Konakov, A. A.; Burdov, V. A.

    2016-10-01

    The rates of resonant and nearly resonant tunnel transitions have been calculated within the envelope function approximation for electrons and holes in silicon nanocrystals embedded in a silicon dioxide matrix. It is shown that, if the nanocrystals are close enough, the rates of resonant tunneling reach the values of the order of 1012-1014 s-1, which considerably exceed the rates of radiative recombination and other basic non-radiative processes, such as the Auger recombination and capture on surface defects. The transition rate is found to be very sensitive to inter-crystallite distance, crystallite size, and effective mass of the carriers in the oxide matrix. Electron tunneling turns out to be faster than the hole one, especially, at greater distances between the nanocrystals. Thus, the tunnel migration in a dense ensemble of nanocrystals is mainly electronic.

  13. [PAH Cations as Viable Carriers of DIBs

    NASA Technical Reports Server (NTRS)

    Snow, Ted

    1998-01-01

    This report is intended to fill in the blanks in NASA's file system for our lab astro study of molecular ions of astrophysical interest. In order to give NASA what it needs for its files, I attach below the text of the section from our recent proposal to continue this work, in which we describe progress to date, including a large number of publications. Our initial studies were focused on PAH cations, which appear to be viable candidates as the carriers of the DIBs, an idea that has been supported by laboratory spectroscopy of PAH cations in inert matrices. Beginning with the simplest aromatic (benzene; C6H6) and moving progressively to larger species (naphthalene, C10OH8; pyrene, C16H10; and most recently chrysene, C18H12), we have been able to derive rate coefficients for reactions with neutral spices that are abundant in the diffuse interstellar medium.

  14. Intratumoral Drug Delivery with Nanoparticulate Carriers

    PubMed Central

    Holback, Hillary

    2011-01-01

    Stiff extracellular matrix, elevated interstitial fluid pressure, and the affinity for the tumor cells in the peripheral region of a solid tumor mass have long been recognized as significant barriers to diffusion of small-molecular-weight drugs and antibodies. However, their impacts on nanoparticle-based drug delivery have begun to receive due attention only recently. This article reviews biological features of many solid tumors that influence transport of drugs and nanoparticles and properties of nanoparticles relevant to their intratumoral transport, studied in various tumor models. We also discuss several experimental approaches employed to date for enhancement of intratumoral nanoparticle penetration. The impact of nanoparticle distribution on the effectiveness of chemotherapy remains to be investigated and should be considered in the design of new nanoparticulate drug carriers. PMID:21213021

  15. Microemulsions as carriers for therapeutic molecules.

    PubMed

    Mehta, Surinder K; Kaur, Gurpreet

    2010-01-01

    The thrust for finding newer drug delivery systems for exiting therapeutic molecules has opened a wide window for colloidal systems. Due to the presence of different domains of variable polarity in the microemulsion systems, they show a huge potential to be used as drug delivery vehicles for a variety of drugs. The use of microemulsion as drug delivery vehicles through a number of routes has engaged a large number of research groups in this area. Microemulsion media finds several applications ranging from drug delivery to drug nanoparticle templating due to its ability to enhance solubility, stability and bioavailability. This review on patent articles recounts the patent literature dealing with different kind of microemulsion carriers used via different routes, solubility and permeability enhancement and its use as a template for nanoparticle synthesis. PMID:19807681

  16. Carbon phosphide monolayers with superior carrier mobility

    NASA Astrophysics Data System (ADS)

    Wang, Gaoxue; Pandey, Ravindra; Karna, Shashi P.

    2016-04-01

    Two dimensional (2D) materials with a finite band gap and high carrier mobility are sought after materials from both fundamental and technological perspectives. In this paper, we present the results based on the particle swarm optimization method and density functional theory which predict three geometrically different phases of the carbon phosphide (CP) monolayer consisting of sp2 hybridized C atoms and sp3 hybridized P atoms in hexagonal networks. Two of the phases, referred to as α-CP and β-CP with puckered or buckled surfaces are semiconducting with highly anisotropic electronic and mechanical properties. More remarkably, they have the lightest electrons and holes among the known 2D semiconductors, yielding superior carrier mobility. The γ-CP has a distorted hexagonal network and exhibits a semi-metallic behavior with Dirac cones. These theoretical findings suggest that the binary CP monolayer is a yet unexplored 2D material holding great promise for applications in high-performance electronics and optoelectronics.Two dimensional (2D) materials with a finite band gap and high carrier mobility are sought after materials from both fundamental and technological perspectives. In this paper, we present the results based on the particle swarm optimization method and density functional theory which predict three geometrically different phases of the carbon phosphide (CP) monolayer consisting of sp2 hybridized C atoms and sp3 hybridized P atoms in hexagonal networks. Two of the phases, referred to as α-CP and β-CP with puckered or buckled surfaces are semiconducting with highly anisotropic electronic and mechanical properties. More remarkably, they have the lightest electrons and holes among the known 2D semiconductors, yielding superior carrier mobility. The γ-CP has a distorted hexagonal network and exhibits a semi-metallic behavior with Dirac cones. These theoretical findings suggest that the binary CP monolayer is a yet unexplored 2D material holding great

  17. Hydrogen - Energy carrier of the future

    NASA Astrophysics Data System (ADS)

    Nitsch, Joachim; Steeb, Hartmut

    1986-11-01

    The potential of hydrogen as an energy carrier - in conventional burners, in internal-combustion or turbine engines, in fuel cells, in catalytic burners, or in steam generators - is discussed, and the current status of the Hysolar program is reviewed. Hysolar is a cooperative project of the University of Stuttgart, DFVLR, and Saudi Arabia to develop industrial-scale hydrogen-production facilities employing solar-cell arrays and electrolysis. Hysolar calls for basic research in photoelectrochemistry, electrolysis, and fuel-cell technology; studies of hydrogen production systems and application technology; training of personnel; and construction of a 2-kW laboratory installation at Jiddah, a 10-kW experimental installation at Stuttgart, and a 100-kW demonstration installation at Riad (producing about 44,000 N cu m of hydrogen per year). Diagrams, drawings, and tables are provided.

  18. Suspected meningococcal meningitis on an aircraft carrier.

    PubMed

    Farr, Wesley; Gonzalez, Michele J; Garbauskas, Heather; Zinderman, Craig E; LaMar, James E

    2004-09-01

    A suspected case of meningococcal meningitis was diagnosed in a 24-year-old sailor onboard an aircraft carrier at sea in 2003. He was immediately confined to the ship's hospital ward under respiratory isolation precautions and was treated with intravenously administered antibiotics. His illness resolved without sequelae. A total of 99 close contacts from the ship were identified and given antibiotic prophylaxis, with directly observed therapy. British public health authorities were contacted to trace and treat persons identified as close contacts during a port call a few days before presentation. Managing a communicable disease such as meningococcal meningitis in the austere shipboard environment represents a unique challenge to military medical personnel. Successful management is possible through prompt treatment, respiratory isolation, and open communication between primary health care providers and public health officials. The identification of shipboard close contacts and other infection control procedures used by the ship's medical department are reviewed.

  19. Photocatalytic removal of 2,4-dichlorophenoxyacetic acid herbicide on copper oxide/titanium dioxide prepared by co-precipitation method

    NASA Astrophysics Data System (ADS)

    Lee, Shu Chin; Hasan, Norhasnita; Lintang, Hendrik O.; Shamsuddin, Mustaffa; Yuliati, Leny

    2016-02-01

    In this work, suppression of the charge recombination on the titanium dioxide (TiO2) was reported by the addition of copper oxide (CuO), which led to a higher activity of TiO2 for removal of 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide. A series of CuO/TiO2 with CuO loadings of 0.1-1 wt% was prepared through a co-precipitation method. X-ray diffraction patterns revealed that the presence of CuO could not be detected as the low loading amount of CuO might have good dispersion on the surface of TiO2. Diffuse reflectance UV-visible spectra suggested that low loading amount of CuO did not influence the optical property of TiO2. Fluorescence spectroscopy revealed that TiO2 possessed a dominant emission peak of 407 nm at an excitation wavelength of 218 nm. The increasing loading amount of CuO decreased the emission intensity of TiO2, suggesting the successful reduction of charge recombination. After irradiation under UV light for 1 h, CuO(0.1 wt%)/TiO2 gave the highest percentage removal of the herbicide among the samples. The optimum loading amount of CuOmight improve the charge separation and reduce the electron-hole recombination on TiO2 without blocking the active sites, thus leading to the improved photocatalytic activity. This work showed that CuO/TiO2 is a potential photocatalyst for environmental remediation.

  20. Drug delivery system for an anticancer agent, chlorogenate-Zn/Al-layered double hydroxide nanohybrid synthesised using direct co-precipitation and ion exchange methods

    NASA Astrophysics Data System (ADS)

    Barahuie, Farahnaz; Hussein, Mohd Zobir; Arulselvan, Palanisamy; Fakurazi, Sharida; Zainal, Zulkarnain

    2014-09-01

    A nano-structured drug-inorganic clay hybrid involving an active anticancer compound, which is chlorogenic acid (CA) intercalated into Zn/Al-layered double hydroxide, has been assembled via ion-exchange and co-precipitation methods to form a nanohybrid CZAE (a chlorogenic acid-Zn/Al nanohybrid synthesised using an ion-exchange method) and CZAC (a chlorogenic acid-Zn/Al nanohybrid synthesised using a direct method), respectively. The X-ray diffraction (XRD) results confirmed that the CA-LDH had a hybrid structure in which the anionic chlorogenate is arranged between the interlayers as a horizontal monolayer at 90 and 20° angles from the x axis for CZAE and CZAC, respectively. Both nanohybrids have the properties of mesoporous materials. The high loading percentage of chlorogenic acid (approximately 43.2% for CZAE and 45.3% for CZAC) with basal spacings of 11.7 and 12.6 Å for CZAE and CZAC, respectively, corroborates the successful intercalation of chlorogenic acid into the interlayer gallery of layered double hydroxides. Free chlorogenic acid and the synthesised nanocomposites (CZAE, CZAC) were assessed for their cytotoxicity against various cancer cells. The Fourier transform infrared data supported the formation of both nanohybrids, and a thermal analysis showed that the nanohybrids are more thermally stable than their counterparts. The chlorogenate shows a sustained release, and the release rate of chlorogenate from CZAE and CZAC nanohybrids at pH 7.4 is remarkably lower than that at pH 4.8 due to their different release mechanisms. The release rate of chlorogenate from both nanohybrids can be described as pseudo-second order. The present investigation revealed the potential of the nanohybrids to enhance the in vitro anti-tumour effect of chlorogenic acid in liver and lung cancer cells in vitro.

  1. A Systems View of the Differences between APOE ε4 Carriers and Non-carriers in Alzheimer's Disease.

    PubMed

    Jiang, Shan; Tang, Ling; Zhao, Na; Yang, Wanling; Qiu, Yu; Chen, Hong-Zhuan

    2016-01-01

    APOE ε4 is the strongest genetic risk factor for late-onset Alzheimer's disease (AD) and accounts for 50-65% of late-onset AD. Late-onset AD patients carrying or not carrying APOE ε4 manifest many clinico-pathological distinctions. Thus, we applied a weighted gene co-expression network analysis to identify specific co-expression modules in AD based on APOE ε4 stratification. Two specific modules were identified in AD APOE ε4 carriers and one module was identified in non-carriers. The hub genes of one module of AD APOE ε4 carriers were ISOC1, ENO3, GDF10, GNB3, XPO4, ACLY and MATN2. The other module of AD APOE ε4 carriers consisted of 10 hub genes including ANO3, ARPP21, HPCA, RASD2, PCP4 and ADORA2A. The module of AD APOE ε4 non-carriers consisted of 16 hub genes including DUSP5, TNFRSF18, ZNF331, DNAJB5 and RIN1. The module of AD APOE ε4 carriers including ISOC1 and ENO3 and the module of non-carriers contained the most highly connected hub gene clusters. mRNA expression of the genes in the cluster of the ISOC1 and ENO3 module of carriers was shown to be correlated in a time-dependent manner under APOE ε4 treatment but not under APOE ε3 treatment. In contrast, mRNA expression of the genes in the cluster of non-carriers' module was correlated under APOE ε3 treatment but not under APOE ε4 treatment. The modules of carriers demonstrated genetic bases and were mainly enriched in hereditary disorders and neurological diseases, energy metabolism-associated signaling and G protein-coupled receptor-associated pathways. The module including ISOC1 and ENO3 harbored two conserved promoter motifs in its hub gene cluster that could be regulated by common transcription factors and miRNAs. The module of non-carriers was mainly enriched in neurological, immunological and cardiovascular diseases and was correlated with Parkinson's disease. These data demonstrate that AD in APOE ε4 carriers involves more genetic factors and particular biological processes, whereas AD

  2. Potential of hafnium nitride for the hot carrier solar cell

    NASA Astrophysics Data System (ADS)

    Chung, Simon; Shrestha, Santosh; Xia, Hongze; Gupta, Neeti; Conibeer, Gavin

    2013-12-01

    The Hot Carrier solar cell is a third generation photovoltaic concept which has the potential to achieve high efficiencies, exceeding the Shockley-Queisser limit for a conventional p-n junction solar cell. The theoretical efficiencies achievable for the Hot Carrier solar cell is 65% for non-concentrated solar radiation and 85% for maximally concentrated light, very close to the limits of an infinite tandem solar cell. The approach of the Hot Carrier solar cell is to extract carriers generated before thermalisation to the bandgap edge occurs when their excess energy is lost to the environment as heat. To achieve this, the rate of carrier cooling in the absorber must be slowed down sufficiently enough to allow carriers to be collected while they are hot. This work investigates using hafnium nitride as such an absorber to restrict mechanisms of carrier cooling. Hafnium nitride's phononic properties, where a large `phononic band gap' exist can reduce the carrier cooling rate by means of a phonon bottleneck such that optical phonons cannot decay into acoustic phonons by means of the Klemens' mechanism. Optical phonon-electron scattering can maintain a hot electron population while acoustic phonons are irrecoverable and lost as heat. The electronic and phononic properties of hafnium nitride are evaluated for their suitability to be used in a Hot Carrier solar cell absorber. Recent work on the fabrication of hafnium nitride at UNSW is presented.

  3. Executive Dysfunction in Female FMR1 Premutation Carriers.

    PubMed

    Shelton, Annie L; Cornish, Kim M; Kraan, Claudine M; Lozano, Reymundo; Bui, Minh; Fielding, Joanne

    2016-10-01

    There is now growing evidence of cognitive weakness in female premutation carriers (between 55 and 199 CGG repeats) of the fragile X mental retardation gene, including impairments associated with executive function. While an age-related decline in assessments of executive function has been found for male premutation carriers, few studies have explored whether female carriers show a similar trajectory with age. A total of 20 female premutation carriers and 21 age- and IQ-matched healthy controls completed a battery of tasks assessing executive function tasks, including the behavioural dyscontrol scale (BDS), symbol digit modalities test (SDMT), paced auditory serial addition test (PASAT), Haylings sentence completion test and the digit span task (forward and backward). Performance was compared between premutation carriers and healthy controls, and the association between task performance and age was also ascertained. Compared to controls, female premutation carriers had significant impairment on the BDS, SDMT, PASAT, and Haylings sentence completion task, all of which rely on quick, or timed, responses. Further analyses revealed no significant association between age and task performance for either premutation carriers or controls. This study demonstrates that a cohort of female premutation carriers have deficits on a range of tasks of executive function that require the rapid temporal resolution of responses. We propose that the understanding of the phenotype of premutation carriers will be advanced through use of such measures. PMID:27126308

  4. Ultrafast carrier dynamics in polycrystalline bismuth telluride nanofilm

    SciTech Connect

    Jia, Lin; Ma, Weigang; Zhang, Xing

    2014-06-16

    In this study, the dynamics of energy carriers in polycrystalline bismuth telluride nanofilm are investigated by the ultrafast pump-probe method. The energy relaxation processes are quantitatively analyzed by using the numerical fitting models. The extracted hot carrier relaxation times of photon excitation, thermalization, and diffusion are around sub-picosecond. The initial reflectivity recovery is found to be dominantly determined by the carrier diffusion, electron-phonon coupling, and photo-generated carriers trapping processes. High-frequency and low-frequency oscillations are both observed and attributed to coherent optical phonons and coherent acoustic phonons, respectively.

  5. 50 CFR 14.141 - Consignment to carrier.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., POSSESSION, TRANSPORTATION, SALE, PURCHASE, BARTER, EXPORTATION, AND IMPORTATION OF WILDLIFE AND PLANTS... Consignment to carrier. Species that grow antlers shall not be accepted for transport unless the antlers...

  6. 50 CFR 14.141 - Consignment to carrier.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., POSSESSION, TRANSPORTATION, SALE, PURCHASE, BARTER, EXPORTATION, AND IMPORTATION OF WILDLIFE AND PLANTS... Consignment to carrier. Species that grow antlers shall not be accepted for transport unless the antlers...

  7. A Systems View of the Differences between APOE ε4 Carriers and Non-carriers in Alzheimer’s Disease

    PubMed Central

    Jiang, Shan; Tang, Ling; Zhao, Na; Yang, Wanling; Qiu, Yu; Chen, Hong-Zhuan

    2016-01-01

    APOE ε4 is the strongest genetic risk factor for late-onset Alzheimer’s disease (AD) and accounts for 50–65% of late-onset AD. Late-onset AD patients carrying or not carrying APOE ε4 manifest many clinico-pathological distinctions. Thus, we applied a weighted gene co-expression network analysis to identify specific co-expression modules in AD based on APOE ε4 stratification. Two specific modules were identified in AD APOE ε4 carriers and one module was identified in non-carriers. The hub genes of one module of AD APOE ε4 carriers were ISOC1, ENO3, GDF10, GNB3, XPO4, ACLY and MATN2. The other module of AD APOE ε4 carriers consisted of 10 hub genes including ANO3, ARPP21, HPCA, RASD2, PCP4 and ADORA2A. The module of AD APOE ε4 non-carriers consisted of 16 hub genes including DUSP5, TNFRSF18, ZNF331, DNAJB5 and RIN1. The module of AD APOE ε4 carriers including ISOC1 and ENO3 and the module of non-carriers contained the most highly connected hub gene clusters. mRNA expression of the genes in the cluster of the ISOC1 and ENO3 module of carriers was shown to be correlated in a time-dependent manner under APOE ε4 treatment but not under APOE ε3 treatment. In contrast, mRNA expression of the genes in the cluster of non-carriers’ module was correlated under APOE ε3 treatment but not under APOE ε4 treatment. The modules of carriers demonstrated genetic bases and were mainly enriched in hereditary disorders and neurological diseases, energy metabolism-associated signaling and G protein-coupled receptor-associated pathways. The module including ISOC1 and ENO3 harbored two conserved promoter motifs in its hub gene cluster that could be regulated by common transcription factors and miRNAs. The module of non-carriers was mainly enriched in neurological, immunological and cardiovascular diseases and was correlated with Parkinson’s disease. These data demonstrate that AD in APOE ε4 carriers involves more genetic factors and particular biological processes

  8. CARRIER PREPARATION BUILDING MATERIALS HANDLING SYSTEM DESCRIPTION DOCUMENT

    SciTech Connect

    E.F. Loros

    2000-06-28

    The Carrier Preparation Building Materials Handling System receives rail and truck shipping casks from the Carrier/Cask Transport System, and inspects and prepares the shipping casks for return to the Carrier/Cask Transport System. Carrier preparation operations for carriers/casks received at the surface repository include performing a radiation survey of the carrier and cask, removing/retracting the personnel barrier, measuring the cask temperature, removing/retracting the impact limiters, removing the cask tie-downs (if any), and installing the cask trunnions (if any). The shipping operations for carriers/casks leaving the surface repository include removing the cask trunnions (if any), installing the cask tie-downs (if any), installing the impact limiters, performing a radiation survey of the cask, and installing the personnel barrier. There are four parallel carrier/cask preparation lines installed in the Carrier Preparation Building with two preparation bays in each line, each of which can accommodate carrier/cask shipping and receiving. The lines are operated concurrently to handle the waste shipping throughputs and to allow system maintenance operations. One remotely operated overhead bridge crane and one remotely operated manipulator is provided for each pair of carrier/cask preparation lines servicing four preparation bays. Remotely operated support equipment includes a manipulator and tooling and fixtures for removing and installing personnel barriers, impact limiters, cask trunnions, and cask tie-downs. Remote handling equipment is designed to facilitate maintenance, dose reduction, and replacement of interchangeable components where appropriate. Semi-automatic, manual, and backup control methods support normal, abnormal, and recovery operations. Laydown areas and equipment are included as required for transportation system components (e.g., personnel barriers and impact limiters), fixtures, and tooling to support abnormal and recovery operations. The

  9. European retrievable carrier (Eureca) and evolutionary space carrier for microgravity, Earth observation and technology demonstration

    NASA Technical Reports Server (NTRS)

    Mory, R.; Seibert, G.

    1984-01-01

    The Spacelab relatively short stay-time in orbit has led to consideration of the European Retrievable Carrier (EURECA) concept as a reusable carrier. The EURECA concept is a free-flying carrier of experiments which is launched and recovered by the space shuttle. It is commensurate with the size of payloads that can be economically developed in Europe and combines the advantages of Spacelab (high mass and power capability, recovery) with those of a free flyer (extended operating time in a non-polluted environment). The launch of the first EURECA mission is scheduled for October 1987. The Eureca spacecraft will be deployed from the Shuttle cargo bay in orbit, will operate in a free-flying mode for about six months, and will then be retrieved, together with its payloads, returned to Earth by the Space Shuttle and prepared for the next mission. The first mission of EURECA is dedicated to research in the fields of life sciences and material sciences. The experimental hardware of the first mission consist of a variety of processin chambers for crystal growth and equipment for biological investigations viz plant growth and protein crystallization, and there is the possibility to perform experiments in the field of exobiology.

  10. 28 CFR 25.55 - Responsibilities of insurance carriers.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Responsibilities of insurance carriers... SYSTEMS National Motor Vehicle Title Information System (NMVTIS) § 25.55 Responsibilities of insurance... individual or entity acting as an insurance carrier conducting business within the United States...

  11. Heat to electricity conversion by cold carrier emissive energy harvesters

    SciTech Connect

    Strandberg, Rune

    2015-12-07

    This paper suggests a method to convert heat to electricity by the use of devices called cold carrier emissive energy harvesters (cold carrier EEHs). The working principle of such converters is explained and theoretical power densities and efficiencies are calculated for ideal devices. Cold carrier EEHs are based on the same device structure as hot carrier solar cells, but works in an opposite way. Whereas a hot carrier solar cell receives net radiation from the sun and converts some of this radiative heat flow into electricity, a cold carrier EEH sustains a net outflux of radiation to the surroundings while converting some of the energy supplied to it into electricity. It is shown that the most basic type of cold carrier EEHs have the same theoretical efficiency as the ideal emissive energy harvesters described earlier by Byrnes et al. In the present work, it is also shown that if the emission from the cold carrier EEH originates from electron transitions across an energy gap where a difference in the chemical potential of the electrons above and below the energy gap is sustained, power densities slightly higher than those given by Byrnes et al. can be achieved.

  12. 47 CFR 69.153 - Presubscribed interexchange carrier charge (PICC).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... period lines less revenues recovered through the End User Common Line charge established under § 69.152... charge revenues. (b) If an end-user customer does not have a presubscribed interexchange carrier, the local exchange carrier may collect the PICC directly from the end user. (c) (d) Local exchange...

  13. 47 CFR 69.153 - Presubscribed interexchange carrier charge (PICC).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... period lines less revenues recovered through the End User Common Line charge established under § 69.152... charge revenues. (b) If an end-user customer does not have a presubscribed interexchange carrier, the local exchange carrier may collect the PICC directly from the end user. (c) (d) Local exchange...

  14. 47 CFR 69.153 - Presubscribed interexchange carrier charge (PICC).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... period lines less revenues recovered through the End User Common Line charge established under § 69.152... charge revenues. (b) If an end-user customer does not have a presubscribed interexchange carrier, the local exchange carrier may collect the PICC directly from the end user. (c) (d) Local exchange...

  15. 47 CFR 69.153 - Presubscribed interexchange carrier charge (PICC).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... period lines less revenues recovered through the End User Common Line charge established under § 69.152... charge revenues. (b) If an end-user customer does not have a presubscribed interexchange carrier, the local exchange carrier may collect the PICC directly from the end user. (c) (d) Local exchange...

  16. 47 CFR 54.405 - Carrier obligation to offer Lifeline.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... (CONTINUED) UNIVERSAL SERVICE Universal Service Support for Low-Income Consumers § 54.405 Carrier obligation...-day time period. A carrier providing Lifeline service in a state that has dispute resolution... information must be reported by month and must be submitted to the Commission at the time an...

  17. Coated metal sintering carriers for fuel cell electrodes

    DOEpatents

    Donelson, R.; Bryson, E.S.

    1998-11-10

    A carrier is described for conveying components of a fuel cell to be sintered through a sintering furnace. The carrier comprises a metal sheet coated with a water-based carbon paint, the water-based carbon paint comprising water, powdered graphite, an organic binder, a wetting agent, a dispersing agent and a defoaming agent.

  18. 49 CFR 1139.22 - Revenue data for study carriers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Intercity Bus Industry § 1139.22 Revenue data for study carriers. The study carriers, as identified above... on the issue traffic, and to evaluate the revenue aspects of the non-issue traffic, including that traffic subject to Surface Transportation Board rate regulation but not here at issue, and that...

  19. 49 CFR 1139.22 - Revenue data for study carriers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Intercity Bus Industry § 1139.22 Revenue data for study carriers. The study carriers, as identified above... on the issue traffic, and to evaluate the revenue aspects of the non-issue traffic, including that traffic subject to Surface Transportation Board rate regulation but not here at issue, and that...

  20. 19 CFR 128.11 - Express consignment carrier application process.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 19 Customs Duties 1 2014-04-01 2014-04-01 false Express consignment carrier application process. 128.11 Section 128.11 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY EXPRESS CONSIGNMENTS Administration § 128.11 Express consignment carrier application process. (a) Facility...