The constant composition technique has been used to study the influence of polymeric additives on the kinetics of crystal growth of hydroxyapatite, HAP, at pH = 7.40, 37°C, and at low supersaturation. The polymeric additives investigated include: Polyacrylic acid, PAA, ( MW 800--50,000); Polyacrylamide, PAM; Poly (2-acrylamido-2-methyl propane sulfonic acid), PSA; and Poly (diallyldimethyl ammonium chloride), PDADMAC. The effect of these additives has been studied at several additive concentrations. It has been found that addition of low levels of PM of low molecular weight to the calcium phosphate supersaturated solution will markedly retard the rates of crystallization of HAP and the fractional reduction in rate constant can be interpreted in terms of the blocking of active growth sites through the adsorption of the PAA ions at the crystal surface. The kinetic data in the presence of PAA suggest optimum performance with an ~ 2,000 molecular weight. Based upon the kinetic data, the order of additive effectiveness is as follows: PAA >> PSA > PAM = PDADMAC = control (no polymer).

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Effect of potassium polyvinylsulfate(Sulf. PVA) on the formation of hydroxyapatite(HAP) via amorphous calcium phosphate (ACP) in an aqueous phase was studied in the presence of 0.9 % NaCl at 35°C Sulf. PVA retarded the transformation of ACP to HAP, although polyvinylalcohol(PVA) showed no effects on the formation. This effect became more significant with increases in the concentration and degree of sulfation( α ) of Sulf. PVA. This was explained in terms of (1)the crystal poisoning through isomorphous substitution and (2)electrostatic repulsion against Pi in the adsorption layer of Sulf. PVA on the HAP seed surface.

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Bovine serum albumin(BSA) retarded the transformation to hydroxyapatite(HAP) from amorphous calcium phosphate(ACP) which was formed immediately after mixing CaCl₂ wit K₂HPO₄ in an aqueous phase. It was experimentally confirmed that the higher the concentration of BSA, the more the uptake of phosphate ion(Pi) from a mother solution was delayed. The mechanism for the retardation was as follows: The crystal nucleus and/or embryo of HAP adsorbs BSA. It could inhibit Pi from getting to the active site for the crystal growth of HAP due mainly to electrostatic and steric repulsion, because the solution pH was higher than that of isoelectric point for BSA(i.e.p.= pH 4.8-5.3) and, therefore, Pi and BSA are repulsive each other. The retardation effect was more remarkable in the presence than in the absence of phosphorylated cellulose(Phos. Cell).

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ydroxyapatite (HAp) was synthesized using sol-gel method in reaction of Ca-C₂H₄(OH)₂-(C₂H₅O)₃P-C₂H₅OH system. The dried gel consisting of calcium and phosphoric alcoholates was synthesized from the reaction between (C₂H₅O)₃P in ethanol and calcium ethoxide which was prepared from the reaction between metallic Ca and C₂H₄(OH)₂. The synthetic conditions were the starting Ca/P atomic ratio of 1.67, synthetic temperature of 25°C and aging time above 12 hours. The gel was finally changed to HAp by heating. We succeeded in synthesis of HAp with very little calcium-deficiency using this sol-gel method.

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We investigated the procedure to prepare hydroxyapatite (HAp; Ca₁₀(PO₄)₆(OH)₂) thin films on alumina substrates by the sol-gel process. Calcium oxide free HAp films were prepared by the use of acetate as a raw material of calcium and rapid heating at 1000°C for 1hr. The films were chemically bonded with the substrates and had a porous structure which was expected to show a good bioactivity.

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The hydraulic hardened bodies were prepared from the thermal decomposition product of hydroxyapatite containing 2-hydroxyethyl methacrylate (HEMA). The hardened bodies were composed of calcium deficient hydroxyapatite, tetracalcium phosphate (TeCP) and polyhydroxyethyl methacrylate (PHEMA). By addition of a crosslinking agent (N,N¹-methylenebisacrylamide) the flexural strength of the hardened bodies containing PHEMA became a little higher than that of the hardened bodies without additives. It seems that appropriate crosslinking strengthened the polymer added, then the increase of polymer strength leaded to increasing the flexural strength of the hardened bodies with additives.

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A new technique for preparation of powders in multi-component system such as hydroxyapatite under hydrothermal conditions was designed. In this technique, Ca(NO₃)₂ and (NH₄)₂HPO₄ solutions separately heated to a desired reaction temperature in a multi-chamber autoclave were mixed to start the reaction under hydrothermal conditions. Hydroxyapatite crystals prepared at high temperatures above 150°C by this technique grew larger with higher aspect ratio than those obtained at the same temperature from the gel prepared by mixing the two solutions at room temperature.

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Apatite (DAp) was formed on stainless steel through a two-step process, i. e., electrodeposition of brushite (DCPD) and its conversion into DAp in solution. The deposition of DCPD was conducted by electrolysing an acidic calcium phosphate solution at constant cathodic currents of 2.0 and 5.5mA/cm2 at 30°C. The conversion of thus deposited DCPD into DAp was carried out by soaking in an alkaline solution. The adhesiveness of DCPD deposits to the cathode substrate was points 8~10 by the square scratching test and 9~10 by the adhesive tape detaching test. The adhesiveness of converted DAp was points 0~4 by the tape detaching. While, that of a directly deposited DAp was 8~9.

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In order to develop a biomaterial which has a hopeful bio-activity and a high mechanical strength, we tried to manufacture a composite material of hydroxyapatite(HAp) and titanium (Ti). Mixed powders of HAp and Ti were coated to a surface of Ti rod as a base metal. This composite material was fired by a high-frequency furnace. We observed that a coated layer of a mixture of HAp and Ti was joined closely to a surface of Ti rod. By electron probe microanalysis, we also recognized a density of Ca increased and that of Ti decreased from a contact area to a surface in a coated layer of a mixture of HAp and Ti.

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Adsorption of glycine on amorphous calcium phosphate and its thermal stability were investigated by the reactions in an aqueous solution of CaCl₂-K₂HPO₄-C₂H₅O₂N-KOH system. Characterization of the products was determined by means of X-ray diffraction, thermal analysis (TG-DTA), infrared absorption spectrometry and ion chromatography. The largest quantity of glycine adsorbed on amorphous calcium phosphate having Ca/P atomic ratio of 1.65 was 8.5 mass% when it is synthesized under the conditions of temperature at 0°C, initial pH 10.0 and C₂H₅O₂N /CaCl₂ molar ratio 11.0, and then aged at 40°C. It was proved that the glycine as one of the amino acids was more tightly adsorbed on the surface of amorphous calcium phosphate than on HAp. The glycine adsorbed on amorphous calcium phosphate was started decomposition at above 200°C, was finished at 600°C, and amorphous calcium phosphate was then transformed to α-type tricalcium phosphate at around 660°C.

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The thermal behavior of some phosphates, lithium hydrogen phosphates represented by Li_xH_3-xPO₄ (x=1, 1.5, 2) mixed with potassium dihydrogen phosphate, were investigated using DTA-TG, XRD and HPLC-FIA. These results showed a formation region, and the reason for the formation of cyclic phosphates was discussed.
The formation region in LiH₂PO₄-KH₂PO₄ system, LiH₂PO₄and KH₂PO₄ influenced. The samples of R ( indicated that the molar ratio of LiH₂PO₄ to KH₂PO₄)≅1:1 therefore showed original thermal behaviors in which cyclic phosphates were produced slightly above 450°C. In the Li_1.5H_1.5PO₄-KH₂PO₄ system, the addition of KH₂PO₄ to Li_1.5H_1.5PO₄ greatly influenced the thermal behavior of Li_1.5H_1.5PO₄ and suppressed the change of Li_1.5H_1.5PO₄ to Li₃HP₂O₇, while the addition of Li_1.5H_1.5PO₄ to KH₂PO₄ influenced slightly the thermal behavior of KH₂PO₄. In the Li₂HPO₄-KH₂PO₄ system, the addition of KH₂PO₄ to Li₂HPO₄ influenced slightly the thermal behavior of Li₂HPO₄, while the addition of Li₂HPO₄ to KH₂PO₄ influenced that of KH₂PO₄.
Although the thermal behavior of Li_1.5H_1.5PO₄ due to heating was the disproportionation reaction which was composed of the main-reaction (the formation of linear poly-phosphate) and a side-reaction (that of cyclic-phosphate), the addition of KH₂PO₄ to Li_1.5H_1.5PO₄ restricted the side-reaction to some extent. This seems to be due to the suppression of the formation of Li₃HP₂O₇ producted at first step of the side-reaction.

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Xenotime (YPO₄) fine crystals were synthesized hydrothermally at 150 °C under the saturated vapor pressure of acidic aqueous solution for 3h. The crystals were nonaggregated particles with polyhedral shape of about 30nm in size when phosphoric acid was used for solvent. The rod like particles of about 200 nm in length were obtained when hydrochloric acid was used for solvent. The lattice parameters of xenotime prepared hydrothermally were in good agreement with those of pure YPO₄.

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We propose a new guideline of molecular design of the guest molecule in intercalation compounds based on the results of the intercalation of alkyltrimethyl ammonium ions into γ-titanium phosphate.

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Solid acid property derived from phosphate ions with which the surface OH groups of silica gel fine particles were exchanged, and the catalytic activity were investigated. In the other paper the acid and catalytic properties regarding silica gels modified with phosphate and sulfate ions were reported. Here it was further more examined on the catalytic effect to the loading amount of phosphate ion.

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Glasses containing TiO₂ in the range of 54-71 mol% were prepared in the systems of TiO₂-P₂O₅-GeO₂ and Na₂O-TiO₂-P₂O₅-GeO₂. Some physical properties of these glasses were determined. The thermal expansion coefficients (α) were 2.6-3.5×10^-6°C^-1 in the range from 30-550°C. These values are smaller than those for any other value among known glasses which contain P₂O₅ as the main component. The values are comparable to those of low thermal expansion double phosphate ceramics recently reported.

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Sodium superionic conductors in the Na₂O-Y₂O₃-P₂O₅-SiO₂ system were synthesized by sol-gel methods and difference in ionic conductivity of sintered compacts between synthetic processes were discussed. When the sol-gel processes using moist N₂ were employed, highly homogeneous xerogel was obtained and sintering of the xerogel led to dense compact. However, the sintered sample did not have higher conductivity than samples obtained by other sol-gel processes. The OH residue in the bulk would prevent conduction of sodium ion.

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A Cu-P-Y-O composite oxide compact with a specified composition (denoted as CPY) is an excellent material for humidity sensor. As for how water vapor accesses to the surfaces of a disk-shaped CPY were studied, and it was found that water vapor accessed to the surfaces of CPY mainly through the electrode layer. Also, the relation of pasty electrode material with the humidity characteristic was investigated, and it follows that the type of paste affected strongly not only the humidity characteristic but also the adhesive strength between the electrodes and the surfaces of a CPY disk.

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A porous Y-P-O composite oxide (denoted as YPO-1) was synthesized using a precipitation method. Its surface area was 233 and 156 m²·g^-1 after evacuation at 400 and 600°C, respectively. YPO-1 was amorphous when calcined at 300°C, while it showed distinct diffraction lines of YPO₄ when calcined above 500°C. The acid strength of YPO-1, which was expressed by pKa of indicator, was≥+1.5. The specific catalytic activity per unit weight of YPO-1 for the isomerization of 1-butene increased with an increase in evacuation temperature, reached a maximum at 300°C, and then decreased.

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Silica-alumina was modified by phosphoric acid, and the resulting materials (SiAP) were investigated in terms of catalytic activity and selectivity for n-butene isomerization as well as physicochemical properties. The activity of SiAP catalysts outgassed at 400°C increased sharply with increasing amount of phosphoric acid added, and reached a maximum at 4.8% H₃PO₄: the maximum activity value was about twice of that of the original silica-alumina. This enhancement in activity was accounted for by an increase in Bröonsted acid sites.

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The changes in structure of two boron phosphate samples upon grinding was studied by XRD and FT-IR. Grinding brought about a decrease in XRD intensity of cristobalite-form of boron phosphate, but the extent was small, indicating the structure was stable to grinding. From one boron phosphate sample, a small amount of boria was formed by grinding, while from the other sample no boria was detected. The results indicate that destruction of the structure of boron phosphate is not necessarily accompanied by the formation of boria.

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Changes in catalytic activity and surface area of two boron phosphate samples by grinding were investigated. Grinding initially brought about increases in surface area and catalytic activity for the oligomerization of cis-2-butene. However, when ground for too long time, both surface area and catalytic activity decreased. Although two unground boron phosphate samples were different in activity and surface area, after grinding such differences became quite small.

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The mechanochemical effects of sodium cyclo-triphosphate (P_3m) by various mechanical treatments (vibration mill, grinding mill, planetary mill, and ball mill) were investigated with X-ray analysis and HPLC-FIA, and the differences in the apparatus used were discussed from the changes of phosphate distribution, the crystallite size, and the lattice distortion of P_3m treated. With an increase of treatment period, the crystallite size of P_3m became smaller and its lattice distortion increased, followed by ring-opening reaction. The effects of mechanical treatments upon the ring-opening reaction were the order of; 300 (vibration mill): 10 (planetary mill): 1 (grinding mill): 0.1 (ball mill).

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The arrangement of heterocyclic compound in the intercalation compounds of the α- and γ-type zirconium and titanium phosphates, and the effect of pKa values of guest compounds on the intercalation into layered phosphates, were examined. An appreciable difference in the arrangements of aminopyridines between α- and γ-types was not found. The intercalation of heterocyclic compounds into layered phosphates depended on their pKa values. In the intercalation of heterocyclic compounds, α-type layered phosphate was more strongly influenced by the pKa values of the guest compound than that of γ-type.

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Unprotected adenosine 5'-monophosphate (5'-AMP) was easily phosphorylated at the cis-2', 3'-diol by sodium cyclo-triphosphate (P_3m) to form adenosine 2', 5'-bis (monophosphate) (2', 5'-ADP) and adenosine 3', 5'-bis (monophosphate) (3', 5'-ADP). The optimum condition for the phosphorylation of 5'-AMP with P_3m is the mixing ratio of P_3m to 5'-AMP (5:1), pH12, and room temperature. The yields of 2', 5'-ADP and 3', 5'-ADP were 47.2 and 49.3%, respectively, under the optimum condition. Purification of 2', 5'-ADP and 3', 5'-ADP was carried out with the fractional precipitation method.

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Contrary to complex coacervation, simple one is not much quantitatively studied. Some authors examine polyphosphate coacervate properties such as thermal evolution¹, viscosity² or solubility in acid solutions³. We experimentally induced sodium polyphosphate coacervation by univalent cation supply. This result seems to be inexplicable by present theories^4-5. So, we studied different parameters relating to coacervation and developed a theory of this phenomena for sodium polyphosphate solutions.

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Protonation equilibria of trimeric cyclic anions, cyclo-triphosphate, cyclo-mono-μ-imido-triphosphate, cyclo-di-μ-imido-triphosphate, and cyclo-tri-μ-imido-triphosphate have been investigated potentiometrically at 25±0.5°C under N₂ atmosphere. The first protonation constants of the anions increase with an increase in the number of the imino groups which constitute the ligand molecules. The increase in the basicity of the ligands can primarily be interpreted by the difference in the electronegativity of the bridging oxygen and nitrogen atoms, however, tautomerism of the imidophosphate bonding are also considered to be responsible to the enhancement of the H⁺ ion binding ability of the imidopolyphosphate anions.

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³¹P NMR chemical shift changes upon protonation and deprotonation of anions of cyclo-triphosphate, cyclo-mono-μ-imido-triphosphate, cyclo-di-μ-imido-triphosphate, and cyclo-tri-μ-imido-triphosphate have been measured in order to obtain microscopic information on the proton bindings. It has been revealed that hydrogen bonding is formed among the phosphate groups belonging to the cyclic trimers, probably due to proximity of the neighboring phosphate units fixed to rigid rings.

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Dicalcium cyclo-tetra-μ-imido-tetraphosphate octahydrate has been prepared by adding aqueous calcium chloride into an aqueous cyclo-tetra-μ-imido-tetraphosphoric acid solution. When the cyclo-tetra-μ-imido-tetraphosphate was heated, release of the water of crystallization was observed and a small decomposition of the imidophosphate occurred up to 210°C. The imidophosphate decomposed to produce many kinds of condensed phosphates with or without NH and NH₂ groups at a higher temperature. The sample finally changed to calcium metaphosphate.

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Flow injection method for the selective detection of orthophosphate in the presence of pyrophosphate (diphosphate) was designed to characterize the inorganic pyrophosphatase (EC3. 6. 1. 1)-catalyzed hydrolysis of pyrophosphate. Fast bluecoloration of molybdophosphate by a mixed reductant of Sn (II) and hydrazine sulfate was employed. The proposed method provided kinetic data that were enough to determine a catalytic rate constant and a Michaelis constant. P-31 NMR spectroscopy was also employed to confirm the conversion of pyrophosphate to orthophosphate.

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The thermal decomposition and mass spectrum of N, N', N'', INT''', N''''-pentaphenyliminoimidodiphosphoramide (1) were investigated. It was indicated that 1 decomposed by heating to form mainly N, N', N''-triphenylphosphoric triamide (2) and 2, 2, 4, 4, 6, 6-hexahydro-2, 2, 4, 4, 6, 6-hexakis (phenylamino)-1, 3, 5, 2, 4, 6-triazatriphosphorine (3), and in the mass spectroscopy of 1, the elimination of a phenylamino radical and/or an aniline from the molecular ion and the formation of 2 were observed.

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