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William I. Higuchi - One of the best experts on this subject based on the ideXlab platform.
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a comparative study of the metastable equilibrium solubility behavior of high crystallinity and low crystallinity carbonated apatites using ph and solution strontium as independent variables
Journal of Colloid and Interface Science, 2005Co-Authors: D D Heslop, Arif Ali Baig, Y Bi, Makoto Otsuka, William I. HiguchiAbstract:Abstract Using solution strontium and pH as independent variables, the metastable equilibrium solubility (MES) behavior of two carbonated apatite (CAP) samples has been examined, a high-crystallinity CAP (properties expected to be similar to dental enamel) and a low-crystallinity CAP (properties expected to be similar to bone mineral). CAP samples were prepared by precipitation/digestion: (CAP A: high-crystallinity, 1.3 wt% CO3, synthesized at 85 °C; CAP B: low-crystallinity, 6.4 wt% CO3, synthesized at 50 °C). Baseline MES distributions were determined in a series of 0.1 M acetate buffers containing only calcium and phosphate (no strontium) over a broad range of solution conditions. To assess the influence of strontium, MES profiles were determined in a similar fashion with 20, 40, 60, and 80% of the solution calcium being replaced on an equal molar basis by solution strontium. To determine the Correct Function governing CAP dissolution, ion activity products (IAPs) were calculated from the compositions of buffer solutions based on the hydroxyapatite template (Ca10–nSrn(PO4)6(OH)2 ( n = 0 – 10 )) and the calcium/hydroxide deficient hydroxyapatite template (Ca9–nSrn(HPO4)(PO4)5OH ( n = 0 – 9 )). Findings: (a) for CAP A, at high solution strontium/calcium ratios, the MES profiles were essentially superimposable when the solution IAPs were calculated using the stoichiometry of Ca6Sr4(PO4)6(OH)2 and for CAP B by a stoichiometry of Ca7Sr2(HPO4)(PO4)5OH; (b) for CAP A, at low strontium/calcium ratios, the stoichiometry yielding MES data superpositioning was found to be that of hydroxyapatite and for CAP B, that of calcium/hydroxide deficient hydroxyapatite. When other stoichiometries were assumed, good superpositioning of the data was not possible.
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metastable equilibrium solubility behavior of carbonated apatite in the presence of solution strontium
Calcified Tissue International, 2003Co-Authors: D D Heslop, Arif Ali Baig, Y Bi, William I. HiguchiAbstract:The purpose of this study was to use the concept of metastable equilibrium solubility (MES) to describe the anomalous solubility behavior of carbonated apatite (CAP) in the presence of solution strontium. A CAP sample (4.8 wt% CO3, synthesized at 70°C) was prepared by precipitation. Baseline MES distributions were determined in a series of 0.1 M acetate buffers containing only calcium and phosphate (no strontium) over a broad range of solution conditions. In order to assess the influence of strontium, MES profiles were then determined in a similar fashion with 20, 30, 40, 50, 60, 70, and 80% of the solution calcium being replaced on an equal molar basis by solution strontium. From the compositions of the equilibrating buffer solutions, ion activity products (IAPs) of the form Ca10-nSrn(PO4)6(OH)2 (n = 0–10) were calculated in an attempt to determine the Correct Function governing the dissolution of the CAP preparation. The results demonstrate the following important findings: (a) at high solution strontium/calcium ratios (i.e., when 60% or more of the solution calcium was replaced by strontium), the MES profiles in all the experiments were found to be essentially superimposable when the solution IAPs were calculated using the stoichiometry of Ca6Sr4(PO4)6(OH)2, and (b), at low solution strontium/calcium ratios (i.e., when 40% or less of the solution calcium was replaced by strontium), the stoichiometry yielding MES data superpositioning was found to be that of hydroxyapatite. When other stoichiometries were assumed, good superpositioning of the data was not possible.
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metastable equilibrium solubility behavior of carbonated apatites in the presence of solution fluoride
Joint International Conference on Information Sciences, 2000Co-Authors: Hong Zhuang, Shane J. Colby, Arif Ali Baig, Zeren Wang, Anil Chhettry, William I. HiguchiAbstract:Abstract The aims of the present investigation were to assess the applicability of the metastable equilibrium solubility (MES) concept for the carbonated apatites (CAPs) over a range of pH and a wide range of solution fluoride concentrations and to examine the hypothesis that, in the presence of solution fluoride, a surface complex with the stoichiometry of fluorapatite (FAP) governs the MES behavior. Two CAP samples were prepared by precipitation from reaction media containing calcium nitrate (Ca(NO 3 ) 2 ·4H 2 O) and sodium phosphate (NaH 2 PO 4 ·H 2 O) at two different levels of sodium bicarbonate. The MES distributions of the two CAP preparations were determined by equilibrating approximately 10 mg of CAP powder in 2 L of 0.1 M acetate buffers (ionic strength=0.50 M) at pH 4.5 and 5.5 and at various levels of calcium, phosphate, and fluoride. The fluoride concentrations ranged from 0.03 to 12 ppm. From the compositions of the equilibrating buffer solutions, ion activity products based upon the stoichiometries of hydroxyapatite (HAP) and FAP were calculated in an attempt to determine the Correct Function governing the dissolution of the CAP preparations. The results of this study demonstrated that both CAP preparations exhibit the MES distribution phenomenon in solution media of varying pH and fluoride concentrations. Furthermore, the experimental MES data obtained with both CAP preparations at the lower pH (4.5) and at higher solution fluoride levels (≥0.1 ppm) were essentially superimposable when plotted against the ion activity product based upon the stoichiometry of FAP, suggesting that in the presence of solution fluoride the MES governing surface complex may be an entity possessing a stoichiometry approximated by that of FAP. When the HAP stoichiometry was assumed to represent the surface complex, good superposition of the data was not possible.
Zdeněk Martinec - One of the best experts on this subject based on the ideXlab platform.
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shavel a program for the spherical harmonic analysis of a horizontal vector field sampled in an equiangular grid on a sphere
Computer Physics Communications, 2018Co-Authors: Zdeněk Martinec, David EinspigelAbstract:Abstract A method for performing a spherical harmonic analysis, using observed horizontal components of a tangent vector on a sphere, is presented. The vector data samples are assumed to be provided in an equiangular grid, which essentially simplifies the least-squares analysis by making use of (1) the block diagonal structure of the normal equations of least squares, (2) the even–odd symmetry of the associated Legendre Functions, and (3) the fast Fourier transform of mix-radix. The Correct Function of the program and its numerical precision is verified by applying it to a data set, derived by evaluating a given set of vector spherical harmonic coefficients. That the program works Correctly is demonstrated by the excellent agreement between the input and output spherical harmonic coefficients. Program summary Program Title: SHAVEL Program Files doi: http://dx.doi.org/10.17632/nppz4y7wg7.1 Licensing provisions: GPLv3 Programming language: Fortran 2003, Linux External routines: FFTPACK5.1, CPC program library SPHAN Classification: 4.9, 4.10, 4.11 Nature of problem: The least-squares analysis of horizontal vector field sampled in an equiangular grid on a sphere in terms of horizontal vector spherical harmonics. Solution method: The vector spherical harmonic coefficients of a horizontal vector field are estimated by the method of least-squares adjustment of data samples distributed in an equiangular grid on a sphere. For such a regular grid the normal matrix is sparse and allows the system of the normal equations to be decomposed into a series of subsystems according to azimuthal order m . The solution of each subsystem is sought by the Gauss elimination. The fast Fourier transform of mix-radix is implemented in (i) setting up the right-hand sides of the normal equations, and (ii) performing the spherical harmonic synthesis where the series of spherical harmonics are summed.
Viviana C. Lepek - One of the best experts on this subject based on the ideXlab platform.
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two rieske fe s proteins and tat system in mesorhizobium loti maff303099 differential regulation and roles on nodulation
Frontiers in Plant Science, 2018Co-Authors: Laura A. Basile, Andrés Zalguizuri, Gabriel Briones, Viviana C. LepekAbstract:Mesorhizobium loti MAFF303099 is a rhizobial strain that nodulates Lotus spp. A M. loti MAFF303099 mutant strain affected in the tatC gene was generated. This strain presented an altered protein secretion level to the culture supernatant and also a higher sensitivity to SDS. Its nodulation phenotype on Lotus showed the induction of small and colorless nodules, and in a larger number than those induced by the wild-type strain. In addition, these nodules presented defects in the degree of occupation by rhizobia. Two Rieske Fe/S proteins, encoded by the mll2707 and mlr0970 genes, were predicted as potential Tat substrates in M. loti MAFF303099. The transcriptional expression of mll2707 and mlr0970 genes was analyzed under different oxygen growth conditions. The mll2707 gene was expressed constitutively, while the expression of the mlr0970 gene was only detected under anaerobic and microaerophilic in vitro conditions. Both genes were down-regulated in the tatC mutant strain. mll2707 and mlr0970 mRNAs from the wild-type strain were detected in nodules. Using a translational reporter peptide fusion, we found that the Mll2707 protein was only detectable in the wild-type strain. On the other hand, although Mlr0970 protein was detected in wild-type and tatC mutant strains, its association with the membrane was favored in the wild-type strain. The tatC and the mll2707 mutant strains were affected in the cytochrome c oxidase activity. These results confirm that Mll2707 is required for cytochrome c-dependent respiration and that Tat Functionality is required for the Correct activity of Mll2707. The mll2707 mutant strain showed a nodulation phenotype similar to the tatC mutant strain, although it presented only a slight difference in comparison with wild-type strain in terms of nodule occupation. No defective phenotype was observed in the nodulation with the mlr0970 mutant strain. These results indicate that, of the two Rieske Fe/S proteins coded by M. loti MAFF303099, only Mll2707 expression is required for the induction of effective nodules, and that the Functionality of the Tat system is necessary not only for the Correct Function of this protein, but also for some other protein required in an earlier stage of the nodulation process.
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Table_2_Two Rieske Fe/S Proteins and TAT System in Mesorhizobium loti MAFF303099: Differential Regulation and Roles on Nodulation.DOC
2018Co-Authors: Laura A. Basile, Andrés Zalguizuri, Gabriel Briones, Viviana C. LepekAbstract:Mesorhizobium loti MAFF303099 is a rhizobial strain that nodulates Lotus spp. A M. loti MAFF303099 mutant strain affected in the tatC gene was generated. This strain presented an altered protein secretion level to the culture supernatant and also a higher sensitivity to SDS. Its nodulation phenotype on Lotus showed the induction of small and colorless nodules, and in a larger number than those induced by the wild-type strain. In addition, these nodules presented defects in the degree of occupation by rhizobia. Two Rieske Fe/S proteins, encoded by the mll2707 and mlr0970 genes, were predicted as potential Tat substrates in M. loti MAFF303099. The transcriptional expression of mll2707 and mlr0970 genes was analyzed under different oxygen growth conditions. The mll2707 gene was expressed constitutively, while the expression of the mlr0970 gene was only detected under anaerobic and microaerophilic in vitro conditions. Both genes were down-regulated in the tatC mutant strain. mll2707 and mlr0970 mRNAs from the wild-type strain were detected in nodules. Using a translational reporter peptide fusion, we found that the Mll2707 protein was only detectable in the wild-type strain. On the other hand, although Mlr0970 protein was detected in wild-type and tatC mutant strains, its association with the membrane was favored in the wild-type strain. The tatC and the mll2707 mutant strains were affected in the cytochrome c oxidase activity. These results confirm that Mll2707 is required for cytochrome c-dependent respiration and that Tat Functionality is required for the Correct activity of Mll2707. The mll2707 mutant strain showed a nodulation phenotype similar to the tatC mutant strain, although it presented only a slight difference in comparison with wild-type strain in terms of nodule occupation. No defective phenotype was observed in the nodulation with the mlr0970 mutant strain. These results indicate that, of the two Rieske Fe/S proteins coded by M. loti MAFF303099, only Mll2707 expression is required for the induction of effective nodules, and that the Functionality of the Tat system is necessary not only for the Correct Function of this protein, but also for some other protein required in an earlier stage of the nodulation process.
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Image_3_Two Rieske Fe/S Proteins and TAT System in Mesorhizobium loti MAFF303099: Differential Regulation and Roles on Nodulation.TIF
2018Co-Authors: Laura A. Basile, Andrés Zalguizuri, Gabriel Briones, Viviana C. LepekAbstract:Mesorhizobium loti MAFF303099 is a rhizobial strain that nodulates Lotus spp. A M. loti MAFF303099 mutant strain affected in the tatC gene was generated. This strain presented an altered protein secretion level to the culture supernatant and also a higher sensitivity to SDS. Its nodulation phenotype on Lotus showed the induction of small and colorless nodules, and in a larger number than those induced by the wild-type strain. In addition, these nodules presented defects in the degree of occupation by rhizobia. Two Rieske Fe/S proteins, encoded by the mll2707 and mlr0970 genes, were predicted as potential Tat substrates in M. loti MAFF303099. The transcriptional expression of mll2707 and mlr0970 genes was analyzed under different oxygen growth conditions. The mll2707 gene was expressed constitutively, while the expression of the mlr0970 gene was only detected under anaerobic and microaerophilic in vitro conditions. Both genes were down-regulated in the tatC mutant strain. mll2707 and mlr0970 mRNAs from the wild-type strain were detected in nodules. Using a translational reporter peptide fusion, we found that the Mll2707 protein was only detectable in the wild-type strain. On the other hand, although Mlr0970 protein was detected in wild-type and tatC mutant strains, its association with the membrane was favored in the wild-type strain. The tatC and the mll2707 mutant strains were affected in the cytochrome c oxidase activity. These results confirm that Mll2707 is required for cytochrome c-dependent respiration and that Tat Functionality is required for the Correct activity of Mll2707. The mll2707 mutant strain showed a nodulation phenotype similar to the tatC mutant strain, although it presented only a slight difference in comparison with wild-type strain in terms of nodule occupation. No defective phenotype was observed in the nodulation with the mlr0970 mutant strain. These results indicate that, of the two Rieske Fe/S proteins coded by M. loti MAFF303099, only Mll2707 expression is required for the induction of effective nodules, and that the Functionality of the Tat system is necessary not only for the Correct Function of this protein, but also for some other protein required in an earlier stage of the nodulation process.
David Einspigel - One of the best experts on this subject based on the ideXlab platform.
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shavel a program for the spherical harmonic analysis of a horizontal vector field sampled in an equiangular grid on a sphere
Computer Physics Communications, 2018Co-Authors: Zdeněk Martinec, David EinspigelAbstract:Abstract A method for performing a spherical harmonic analysis, using observed horizontal components of a tangent vector on a sphere, is presented. The vector data samples are assumed to be provided in an equiangular grid, which essentially simplifies the least-squares analysis by making use of (1) the block diagonal structure of the normal equations of least squares, (2) the even–odd symmetry of the associated Legendre Functions, and (3) the fast Fourier transform of mix-radix. The Correct Function of the program and its numerical precision is verified by applying it to a data set, derived by evaluating a given set of vector spherical harmonic coefficients. That the program works Correctly is demonstrated by the excellent agreement between the input and output spherical harmonic coefficients. Program summary Program Title: SHAVEL Program Files doi: http://dx.doi.org/10.17632/nppz4y7wg7.1 Licensing provisions: GPLv3 Programming language: Fortran 2003, Linux External routines: FFTPACK5.1, CPC program library SPHAN Classification: 4.9, 4.10, 4.11 Nature of problem: The least-squares analysis of horizontal vector field sampled in an equiangular grid on a sphere in terms of horizontal vector spherical harmonics. Solution method: The vector spherical harmonic coefficients of a horizontal vector field are estimated by the method of least-squares adjustment of data samples distributed in an equiangular grid on a sphere. For such a regular grid the normal matrix is sparse and allows the system of the normal equations to be decomposed into a series of subsystems according to azimuthal order m . The solution of each subsystem is sought by the Gauss elimination. The fast Fourier transform of mix-radix is implemented in (i) setting up the right-hand sides of the normal equations, and (ii) performing the spherical harmonic synthesis where the series of spherical harmonics are summed.
D D Heslop - One of the best experts on this subject based on the ideXlab platform.
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a comparative study of the metastable equilibrium solubility behavior of high crystallinity and low crystallinity carbonated apatites using ph and solution strontium as independent variables
Journal of Colloid and Interface Science, 2005Co-Authors: D D Heslop, Arif Ali Baig, Y Bi, Makoto Otsuka, William I. HiguchiAbstract:Abstract Using solution strontium and pH as independent variables, the metastable equilibrium solubility (MES) behavior of two carbonated apatite (CAP) samples has been examined, a high-crystallinity CAP (properties expected to be similar to dental enamel) and a low-crystallinity CAP (properties expected to be similar to bone mineral). CAP samples were prepared by precipitation/digestion: (CAP A: high-crystallinity, 1.3 wt% CO3, synthesized at 85 °C; CAP B: low-crystallinity, 6.4 wt% CO3, synthesized at 50 °C). Baseline MES distributions were determined in a series of 0.1 M acetate buffers containing only calcium and phosphate (no strontium) over a broad range of solution conditions. To assess the influence of strontium, MES profiles were determined in a similar fashion with 20, 40, 60, and 80% of the solution calcium being replaced on an equal molar basis by solution strontium. To determine the Correct Function governing CAP dissolution, ion activity products (IAPs) were calculated from the compositions of buffer solutions based on the hydroxyapatite template (Ca10–nSrn(PO4)6(OH)2 ( n = 0 – 10 )) and the calcium/hydroxide deficient hydroxyapatite template (Ca9–nSrn(HPO4)(PO4)5OH ( n = 0 – 9 )). Findings: (a) for CAP A, at high solution strontium/calcium ratios, the MES profiles were essentially superimposable when the solution IAPs were calculated using the stoichiometry of Ca6Sr4(PO4)6(OH)2 and for CAP B by a stoichiometry of Ca7Sr2(HPO4)(PO4)5OH; (b) for CAP A, at low strontium/calcium ratios, the stoichiometry yielding MES data superpositioning was found to be that of hydroxyapatite and for CAP B, that of calcium/hydroxide deficient hydroxyapatite. When other stoichiometries were assumed, good superpositioning of the data was not possible.
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metastable equilibrium solubility behavior of carbonated apatite in the presence of solution strontium
Calcified Tissue International, 2003Co-Authors: D D Heslop, Arif Ali Baig, Y Bi, William I. HiguchiAbstract:The purpose of this study was to use the concept of metastable equilibrium solubility (MES) to describe the anomalous solubility behavior of carbonated apatite (CAP) in the presence of solution strontium. A CAP sample (4.8 wt% CO3, synthesized at 70°C) was prepared by precipitation. Baseline MES distributions were determined in a series of 0.1 M acetate buffers containing only calcium and phosphate (no strontium) over a broad range of solution conditions. In order to assess the influence of strontium, MES profiles were then determined in a similar fashion with 20, 30, 40, 50, 60, 70, and 80% of the solution calcium being replaced on an equal molar basis by solution strontium. From the compositions of the equilibrating buffer solutions, ion activity products (IAPs) of the form Ca10-nSrn(PO4)6(OH)2 (n = 0–10) were calculated in an attempt to determine the Correct Function governing the dissolution of the CAP preparation. The results demonstrate the following important findings: (a) at high solution strontium/calcium ratios (i.e., when 60% or more of the solution calcium was replaced by strontium), the MES profiles in all the experiments were found to be essentially superimposable when the solution IAPs were calculated using the stoichiometry of Ca6Sr4(PO4)6(OH)2, and (b), at low solution strontium/calcium ratios (i.e., when 40% or less of the solution calcium was replaced by strontium), the stoichiometry yielding MES data superpositioning was found to be that of hydroxyapatite. When other stoichiometries were assumed, good superpositioning of the data was not possible.
