Synthesis and physicochemical characterization of carboxymethylcellulose-containing calcium hydroxylapatite

The CaCl₂-(NH₄)₂HPO₄-C₈H₁₁O₇Na-NH₃-H₂O system was studied at 25°C using the solubility method (Tananaev’s residual concentration method) and pH measurements. The solid phases isolated from the system were characterized using chemical analysis, X-ray powder diffraction, IR spectroscopy, and thermogravimetry. Nanocrystalline carboxymethylcellulose-containing calcium hydroxylapatites Ca₁₀(PO₄)₆(OH)₂ · xH₂O · yC₈H₁₁O₇Na with x = 6–12 and y = 0.1–0.5 were found as a result of the characterization.     

Gelatin-containing calcium hydroxyapatites: Synthesis and physicochemical characterization

The CaCl₂-(NH₄-)₂HPO₄-NH₃-H₂O-gelatin system was studied at 25°C using the solubility (residual concentrations) method. Stoichiometric nanocrystalline (11–15.4 nm) gelatin-containing calcium hydroxyapatites (HAs) were found to form. They were characterized by chemical analysis, thermal analysis, Xray powder diffraction, and IR spectroscopy. Original Russian Text ? Zh.A. Ezhova, N.A. Zakharov, E.M. Koval’, V.T. Kalinnikov, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 3, pp. 526–530.     

Synthesis and physicochemical properties of calcium hydroxylapatite/multi-walled carbon nanotubes nanocomposites

Calcium hydroxylapatite/carbon nanotubes (HA/CNT) composites with various CNT contents have been synthesized by coprecipitation from aqueous solutions in the CaCl₂-(NH₄)₂HPO₄-NH₃-CNT-H₂O system (25°C) under conditions modeling the interaction between HA (Ca₁₀(PO₄)₆(OH)₂), which is an inorganic component of osseous tissue, and multi-walled CNTs. The empirical formula of the composites is Ca₁₀(PO₄)₆(OH)₂ · nCNT · 6H₂O, where n = 0.2?C5.0. The synthesis products have been identified by the solubility (Tananaev??s residual concentration) method, pH measurements, chemical analysis, X-ray diffraction, IR spectroscopy, electron spectroscopy for chemical analysis, and scanning and transmission electron microscopy. The effect of the CNT concentration in aqueous solution on the composition of the HA/CNT composites and on the crystallographic and morphological characteristics of HA nanocrystals in HA/CNT has been investigated.     

Synthesis and physicochemical characterization of nanocrystalline chitosan-containing calcium carbonate apatites

The CaCl₂-(NH₄)₂HPO₄-NH₄HCO₃-(C₆H₁₁NO₄) _n -H₂O system at 25°C has been investigated by the solubility (Tananaev’s residual concentration) method and pH measurements. Coprecipitation conditions have been determined for nanocrystalline type A and B calcium carbonate apatites. Type A: Ca₁₀(PO₄)₆(CO₃) _x (OH)_{2 − 2x} · yC₆H₁₁NO₄ · zH₂O (x = 0.2, 0.5, 1.0; y = 0.1, 0.3, 0.5; z = 5.3−6.7); type B: Ca₁₀[(PO₄)_5.7(CO₃)_0.45]CO₃ · 0.3C₆H₁₁NO₄ · 9H₂O, and Ca₁₀[(PO₄)_5.55(CO₃)_0.675]CO₃ · 0.3C₆H₁₁NO₄ · 9.2H₂O. The solid phases have been characterized by chemical analysis, X-ray diffraction, thermogravimetric analysis, and IR spectroscopy.     

Synthesis and physicochemical characterization of nanocomposites of calcium hydroxylapatite-chitosan-multiwall carbon nanotubes

The synthesis and physicochemical characterization of nanocomposites of calcium hydroxylapatite-chitosan-multiwall carbon nanotubes (CNTs) was performed. The CaCl₂-(NH₄)₂HPO₄-(C₆H₁₁NO₄) _n -CNT-NH₃-H₂O system was studied by the solubility (Tananaev’s residual concentration) method and pH measurements at 25°C. Conditions for the joint precipitation of nanocrystalline calcium hydroxylapatite, chitosan, and multiwall CNTs were found. Nanocomposites with the general formula Ca₁₀(PO₄)₆(OH)₂ · x(C₆H₁₁NO₄) · yCNT · zH₂O, where x = 0.1, 0.2, and 0.5; y = 0.5, 2.0, 4.0, and 5.0; and z = 5.9–7.9. The solid phases were characterized by chemical, thermogravimetric, and X-ray diffraction analysis and IR spectroscopy.     

Hydroxyapatite-brushite mixtures: Synthesis and physicochemical characterization

Feasibility was studied whether mixtures containing up to 90 wt % type B hydroxyapatite (Ca/P ≈ 1.50) together with brushite could be synthesized by precipitation from the Ca(NO₃)₂-(NH₄)₂HPO₄-NH₄OH-H₂O system. The synthetic materials were characterized by a set of physicochemical methods. Their behavior was studied during heat treatment and dissolution in isotonic 0.9% NaCl solution.     

Calcium alkoxyalanates : I. Synthesis and physicochemical characterization

Soluble calcium alkoxyalanates, Ca[AlH_4?n(OR)_n]₂, in which n ranges from 1 to 3, generally complexed with tetrahydrofuran, have been obtained by partial alcoholysis of calcium alanate with various branched aliphatic alcohols and with 2-methoxyethanol in toluene. With a few exceptions X-ray powder diffraction patterns and infrared AlH absorptions indicate that the calcium alkoxyalanates are individual molecular species.     

聚甲氧基二甲醚的合成及其物理化学性质表征

聚甲氧基二甲醚（H₃CO（CH₂O）_nCH₃, PODE_n或DMM_n, n ≥ 2）具有独特的物理化学性质;作为一种柴油添加剂,可以有效提高油品燃烧效率并达到节能减排的目的。首先合成了一系列聚合度n为2、3、4和5单一组分的聚甲氧基二甲醚,采用NMR、FT-IR、Raman和DFT计算等手段对每个聚甲氧基二甲醚单体的化学结构进行表征,并对其在298.15-323.15K温度的密度和黏度进行了测试。结果表明,聚甲氧基二甲醚的密度和黏度随着温度的升高而逐渐降低,随着聚合度的增加而逐渐升高。同时,聚甲氧基二甲醚PODE_n（n =2-5）的闪点和倾点以及溶解热和凝固热均随着聚合度的增加而提高。     

聚天冬氨酸钙的合成与表征

螯合的有机酸钙,属于现今钙营养强化剂中的新一代产品[1]。这类钙剂进入血液不是立即解离成钙离子,而是持续离出钙离子供机体利用,从而避免血清中钙离子浓度过高出现高血钙,保证钙元素充分吸收和利用[2,3]。聚天冬氨酸钙具有多肽的化学结构,被人体吸收利用的速度相对要慢、代谢     

Synthesis and physicochemical study of nanocrystalline magnesium-containing calcium hydroxylapatites and chitosan

The interaction in the CaCl₂-MgCl₂-(NH₄)₂HPO₄-NH₃-H₂O and CaCl₂-MgCl₂-(NH₄)₂HPO₄-(C₆H₁₁NO₄) _n -NH₃-H₂O systems at 25°C has been investigated by the solubility (Tananaev’s residual concentration) method and by pH measurements. Magnesium-containing calcium hydroxylapatites with the general formula Mg _x Ca_{10 − x} (PO₄)₆(OH)₂ · nH₂O (x = 0.05, 0.1, 0.2, 0.3; n = 6–7.3) and magnesium- and chitosan-containing calcium hydroxylapatites with the general formula Mg _x Ca_{10 − x} (PO₄)₆(OH)₂ · y(C₆H₁₁NO₄) · nH₂O (x = 0.05, 0.1, 0.2, 0.3; y = 0.1, 0.3, 0.46; n = 6–8.3) have been isolated in the nanocrystalline state. The solids have been characterized by chemical and thermogravimetric analyses, X-ray diffraction, and IR spectroscopy.     

Calcium hydroxylapatite/methylcellulose nanocomposite: Synthesis and properties

Organomineral nanocomposites (OMCs) of calcium hydroxylapatite Ca₁₀(PO₄)₆(OH)₂ (HA) and natural methylcellulose biopolymer [C₆H₇O₂(OH)_{3 ? x} (OCH₃) _x ] _n (MC) were prepared by coprecipitation from aqueous solution in the Ca(OH)₂-H₃PO₄-[C₆H₇O₂(OH)_3?x (OCH₃) _x ] _n -H₂O system under biomimetic conditions (37°C). Synthesis products were identified by X-ray powder diffraction, IR spectroscopy, thermal analysis, scanning and transmission microscopy, and electron diffraction. The compositions and structural features of the OMCs and the crystallographic parameters, sizes, and morphology of HA nanoparticles in the OMCs were determined. The HA nanoparticles in the OMCs were found to interact with MC molecules to form agglomerates with sizes on the order of 150–200 nm.     

Carbohydrazone polychelates: Synthesis,physicochemical characterization,solid state conductance and biological studies

The polychelates of Ti(III), VO(IV), Cr(III), Mn(III), Fe(III), Zr(IV), MoO₂(VI) and UO₂(VI) with the chelating hydrazone derived from 2,4-dihydroxy-5-acetylacetophenone and carbohydrazide have been synthesized. The polychelates have been characterized on the basis of elemental analyses, IR, magnetic moment, electronic spectral data and thermal analysis. Various kinetic parameters have been determined from the thermal data and decomposition follows first order kinetics. The solid—state electrical conductivity has been measured over 40–130°C-temperature range and all the compounds showed semiconducting behavior as their conductivity increases with increase in temperature. The ligand and its polychelates have also been screened for their antimicrobial activities using various microorganisms and all of them were found to be active against the organisms.     

Synthesis and physicochemical properties of antianemic iron and calcium complexes with sodium polygalacturonate

New stable water-soluble metal complexes of citrus pectin (sodium polygalacturonate, PG-Na) with biogenic microelements (Ca and Fe) that we synthesized were characterized by infrared spectroscopy, dynamic light scattering, and atomic force microscopy. The temperature dependence of the mass of PG-Na, PG-NaFe, and PG-NaFeCa samples was studied by simultaneous thermal analysis. Water was found to be the major component of the gas phase in the first stage of mass loss of PG-NaFe and PG-NaFeCa, while the second stage involves decarboxylation and decomposition. The stimulating action of PG-NaFe and PG-NaFeCa on hematopoiesis in outbred rats during growing period, manifested as more than 10% increase in the hemoglobin concentration, was demonstrated.     

New bismuth calcium oxysilicate with apatite structure: Synthesis and structural characterization

New bismuth calcium silicon oxide Ca₄Bi_4.3(SiO₄)(HSiO₄)₅O_0.95, with apatite structure has been synthesized. The structure was refined from powder X-ray diffraction data. The refinement revealed that the phase has P6₃/m (176) space group with unit cell parameters a=b=9.6090(7) Å, c=7.0521(7) Å, V=563.9 Å³ and c/a=0.734. The R_wp factor at Rietveld refinement was equal to 0.082. The synthesized phase has an unusual quantity of cation vacancies in a crystal lattice. Mechanisms of compensation of the excess charge of a lattice are considered and checked experimentally using the FT-IR spectroscopy, the thermal analysis and the XPS analysis.     

Synthesis and physicochemical characteristics of calcium hydroxyapatite/multiwall carbon nanotubes/collagen nanocomposites

Calcium hydroxyapatite/multiwall carbon nanotubes/collagen nanocomposites were synthesized and subjected to physicochemical analysis. The system CaCl₂-(NH₄)₂HPO₄-multiwall carbon nanotubes-NH₃-H₂O-collagen was investigated at 25°C by the solubility method (Tananaev’s residual concentration method) and by pH measurements. Chemical, X-ray powder diffraction, and thermogravimetric analyses and IR spectroscopy showed that, in the system CaCl₂-(NH₄)₂HPO₄-multiwall carbon nanotubes-NH₃-H₂O-collagen under chosen synthesis conditions, nanocomposites comprising nanocrystalline calcium hydroxyapatite (NCHA), multiwall carbon nanotubes (CNT), and collagen form with the composition Ca₁₀(PO₄)₆(OH)₂ · xCNT · yH₂O · z collagen, where x = 1–5; y = 5.5–7.7, and z = 3, 5, and 10 wt %. The obtained nanocomposites are the products of the coprecipitation of CNT, collagen, and NCHA, which forms in the system by the interaction of CaCl₂ and (NH₄)₂HPO₄.     

Synthesis and characterization of new calcium phenylphosphonates and 4-carboxyphenylphosphonates

Three new calcium phenylphosphonates, CaC(6)H(5)PO(3).2H(2)O, Ca(3)(C(6)H(5)PO(3)H)(2)(C(6)H(5)PO(3))(2).4H(2)O, and CaC(6)H(5)PO(3).H(2)O, and two calcium 4-carboxyphenylphosphonates, Ca(HOOCC(6)H(4)PO(3)H)(2) and Ca(3)(OOCC(6)H(4)PO(3))(2).6H(2)O, were prepared. It was found that CaC(6)H(5)PO(3).2H(2)O transformed into previously known Ca(C(6)H(5)PO(3)H)(2) via Ca(3)(C(6)H(5)PO(3)H)(2)(C(6)H(5)PO(3))(2).4H(2)O in the presence of phenylphosphonic acid, and vice versa, Ca(C(6)H(5)PO(3)H)(2) turned into CaC(6)H(5)PO(3).2H(2)O in a weak basic medium. A similar relationship was found between Ca(HOOCC(6)H(4)PO(3)H)(2) and Ca(3)(OOCC(6)H(4)PO(3))(2).6H(2)O; i.e., Ca(3)(OOCC(6)H(4)PO(3))(2).6H(2)O transformed into Ca(HOOCC(6)H(4)PO(3)H)(2) in the presence of 4-carboxyphenylphosphonic acid. On the contrary, Ca(3)(OOCC(6)H(4)PO(3))(2).6H(2)O is formed from Ca(HOOCC(6)H(4)PO(3)H)(2) in the presence of ammonium as a weak base. The structure of Ca(HOOCC(6)H(4)PO(3)H)(2) was solved from X-ray powder diffraction data by an ab initio method using a FOX program. The compound is monoclinic, space group C2/c (No. 15), a = 49.218(3) A, b = 7.7609(4) A, c = 5.4452(3) A, beta = 128.119(3) degrees , and Z = 4. Its structure is one-dimensional with [Ca(2)(HOOCC(6)H(4)PO(3)H)(4)](infinity) ribbons forming basic building blocks. The ribbons are held together by hydrogen bonds between carboxylic groups.