Brushite (CaHPO4·2H2O) to octacalcium phosphate (Ca8(HPO4)2(PO4)4·5H2O) transformation in DMEM solutions at 36.5 °C

The purpose of this study was to investigate the transformation of brushite (dicalcium phosphate dihydrate, DCPD, CaHPO₄·2H₂O) powders at 36.5 °C in DMEM (Dulbecco's Modified Eagle Medium) solutions. Two sets of brushite powders with different particle shapes were synthesized to use in the above DMEM study. The first of these brushite powders was prepared by using a method which consisted of stirring calcite (CaCO₃) powders in a solution of ammonium dihydrogen phosphate (NH₄H₂PO₄) from 6 to 60 min at room temperature. These powders were found to consist of dumbbells of water lily-shaped crystals. The second one of the brushite powders had the common flat-plate morphology. Both powders were separately tested in DMEM-immersion experiments. Monetite (DCPA, CaHPO₄) powders were synthesized with a unique water lily morphology by heating the water lily-shaped brushite crystals at 200 °C for 2 h. Brushite powders were found to transform into octacalcium phosphate (OCP, Ca₈(HPO₄)₂(PO₄)₄·5H₂O) upon soaking in DMEM (Dulbecco's Modified Eagle Medium) solutions at 36.5 °C over a period of 24 h to 1 week. Brushite powders were known to transform into apatite when immersed in synthetic (simulated) body fluid (SBF) solutions. This study found that DMEM solutions are able to convert brushite into OCP, instead of apatite.     

X-ray powder diffraction and IR study of NaMg(H2O)2[BP2O8]·H2O and NH4Mg(H2O)2[BP2O8]·H2O

NaMg(H₂O)₂[BP₂O₈]·H₂O was prepared by hydrothermal synthesis and was characterized by X-ray powder difraction and IR method. The title compound was synthesized from MgCl₂·6H₂O, NaBO₃·4H₂O, and (NH₄)₂HPO₄ with variable molar ratios using hydrothermal method by heating at 165 °C for 3 days. The X-ray powder diffraction data was indexed in hexagonal system, the unit cell parameters were found to be as a = 9.428, c = 15.82 Å, Z = 4 and the space group is P6₁22. It is isostructural with M^lM^ll(H₂O)[BP₂O₈] type compounds where M^l = Na, K; M^ll = Mg, Mn, Fe, Co, Ni and Zn. In addition NH₄Mg(H₂O)₂[BP₂O₈]·H₂O was also synthesized the first time in this research. Its unit cell parameters and hkl values were in good agreement with the sodium magnesium compound. The unit cell parameters are a = 9.529, c = 15.736 Å. The indexed X-ray powder diffraction data of both compounds which were not reported in the literature is presented in this work. The IR data of NaMg(H₂O)₂[BP₂O₈]·H₂O is also reported.     

Crystal structure of a double Np(V) ammonium propionate, NH4[(NpO2)3(C2H5COO)4(H2O)]·3H2O

The structure of NH₄[(NpO₂)₃(C₂H₅COO)₄(H₂O)]·3H₂O was studied by single crystal X-ray diffraction. The single crystals were prepared by hydrothermal synthesis. In the structure, there are three crystallographically independent Np atoms with different equatorial surrounding. All of them have CN 7; the coordination polyhedron is a distorted pentagonal bipyramid. Each NpO ₂ ⁺ cation is bonded to four other cations, acting simultaneously as a bidentate ligand and a coordination center for two other dioxocations. The cation-cation interactions result in formation of trigonal-hexagonal cationic networks.     

Crystal Structure of Neptunium(V) Phthalate (NpO2)2(OOC)2C6H4·4H2O

The crystal structure of (NpO₂)₂(OOC)₂C₆H₄·4H₂O [rhombic cell: a = 15.937(3), b = 26.922(5), c = 8.020(2) Å, space group Pbcn, Z = 8, V = 3441.0(12) ų, d _calc = 2.988 g cm^{- 3}, CAD4, MoK , graphite monochromator, 2934 independent reflections; R ₁ = 0.0352, wR ₂ = 0.0951] was studied. The structure consists of NpO₂ ⁺ cations, H₄C₆(COO)₂ ^{2 -} anions, and molecules of coordinated and crystallization water. The crystal lattice involves neutral layers [(NpO₂)₂(OOC)₂C₆H₄(H₂O)₃] _n parallel to the {101} plane. The dioxocations in these layers are bonded to each other to form cationic networks [the Np···Np distance is 3.911(1)-4.202(1) Å]. The coordination polyhedra of Np(1) and Np(2) are pentagonal bipyramids (CN 7). The point group of the neptunyl(V) groups is close to D _h. These groups are bidentate ligands in the cation-cation interaction. The Np = O bond lengths are 1.852(6) [Np(1)-O(1)], 1.849(7) [Np(1)-O(2)], 1.845(7) [Np(2)-O(3)], and 1.841(7) Å [Np(2)-O(4)]; the O = Np = O bond angles are 178.6(3)° [O(2)-Np(1)-O(1)] and 177.4(3)° [O(3)-Np(2)-O(4)]. The equatorial plane of the Np(1) bipyramid consists of two oxygen atoms of adjacent Np(2)O₂ ⁺ dioxocations, two water molecules, and a single oxygen atom of the phthalate anion. The equatorial plane of the Np(2) bipyramid consists of two oxygen atoms of adjacent Np(1)O₂ ⁺ dioxocations, two oxygen atom of the phthalate anion, and a single water molecule. The bond lengths in the equatorial plane of the bipyramid lie in the following ranges: Np-Oyl 2.373(7)-2.437(7) Å (average 2.397 Å) , Np-Ophth 2.360(7)-2.474(7) Å (average 2.431 Å), and Np-Owater 2.534(8)-2.558(9) Å (average 2.544 Å). The phthalate anions are tridentate bridging ligands binding neptunium atoms only within a single cationic network.     

Complexes with substituted 2,5-dihydroxy-p-benzoquinones: The inclusion compounds [Y(H2O)3]2 (C6Cl2O4)3·6.6H2O and [Y(H2O)3]2 (C6Br2O4)3·6H2O

Single crystal of [Y(H₂O)₃]₂ (C₆Br₂O₄)₃·6H₂O and [Y(H₂O)₃]₂ (C₆Cl₂O₄)₃·6.6H₂O were grown in aqueous silicagel. The compounds are in principle isostructural. In Y chloranilate one additional water site is occupied as verified by X-ray single crystal structure analysis. Y³⁺ is nine-coordinated by three water molecules and six oxygen atoms of the bischelating (C₆X₂O₄)²⁻ ions (XCl, Br). The coordination polyhedron is an only slightly distorted tri-capped trigonal prism. The connection of Y³⁺ with the dianions leads to infinite, corrugated layers. The layer stacking yields cage-like cavities in which water molecules are accomodated. Hydrogen bonds interlink adjacent layers. Further hydrogen bonds involve the entrapped water molecules. DSC measurements indicated a complicated dehydration process which caused right at the start destruction of the single crystals.     

Crystal Structure of An(VI) Complexes with Succinate Anions, [PuO2(C4H4O4)(H2O)] and Cs2[(AnO2)2(C4H4O4)3]·H2O (An = U,Np, Pu)

Radiochemistry - Actinide(VI) complexes with succinate anions [PuO2(succ)(H2O)] and Cs2[(AnO2)2(succ)3]·H2O (An = U, Np, Pu), where succ = [C4H4O4]2 ?, were synthesized and studied by...     

Studies of the critical velocity of superfluid4he in a 2 μm by 2 μm aperture in a thin foil at various frequencies

Measurements of the critical velocity behavior of oscillatory superfluid⁴He flow through a 2 m by 2 m square aperture in a 0.1 m thick titanium foil are being made at temperatures between 0.36 K and 2.1 K and at pressures of less than 0.4 bar at various frequencies between 50 Hz and 1000 Hz. The purpose of this work is to study a micron-size aperture for possible frequency-dependent deviations from the critical velocity behavior seen in submicron-size apertures. Preliminary results show a nearly linear decrease of critical velocity with increasing temperature that is similar to the temperature dependences seen in smaller apertures and that is approximately independent of frequency. However, at frequencies above 500 Hz, a region appears at the lowest temperatures in which supercritical behavior is dominated by large energy-loss events requiring a number of half-cycles for completion, a region that extends up to 1.1 K at 970 Hz.     

Novel self-assembled decavanadate clusters forming 1D molecular chains and 2D molecular arrays: [HMTA-H···H2O][HMTA-CH2OH][H3V10O28{Na(H2O)4}]·4H2O and [Na2(H2O)10] [H3V10O28 {Na(H2O)2}]·3H2O

Two novel materials, [HMTA-H··H₂O] [HMTA-CH₂OH] [H₃V₁₀O₂₈[Na(H₂O)₄}]·4H₂O, 1 and [Na₂(H₂O)₁₀][H₃V₁₀O₂₈[Na(H₂O)₂}]·3H₂O, 2 containing decavanadate clusters interconnected through hydrated sodium cations forming 1D molecular chains and 2D molecular arrays have been self-assembled from acidified, aqueous vanadate solution in the presence of organic bases, hexamethylenetetramine and 1,3,5-triazine respectively.     

Nonlinear Refraction and Absorption in 4BCMU Planar Waveguides at 1·064 μm Wavelength

Abstract

We have measured the nonlinear refractive index, n ₂, and two-photon absorption coefficient, β, in 4BCMU planar waveguides at 1·064 μm wavelength using picosecond pulses. We use a beam propagation code, with n ₂ and β as fitting parameters, to make numerical comparison with the experimental data. Deduced values from this analysis are n₂ = ? 1·5 × 10^?13 cm²W^?1, confirming the negative sign of the nonlinearity at this wavelength, and β = 0·01 cm MW^?1.     

Coupled Surface Plasmons at 3·391 μm

Abstract

Using 3·391 μm wavelength radiation to excite surface plasmons means that the conventional dimensional constraints imposed upon the dielectric thickness required for coupled surface plasmons is relaxed. Results are presented and analysed for coupled surface plasmons using silver layers spaced by a variable air gap of several micrometres thickness. Adjusting the air gap allows the determination of the dispersion curve for the coupled plasmons as a function of gap thickness down to a gap of about 5 μm.     

Synthesis and structure of actinide(VII) compounds Rb3NpO4(OH)2·3H2O and Rb3PuO4(OH)2·3H2O

Actinide(VII) salts Rb₃[NpO₄(OH)₂]·3H₂O (I) and Rb₃[PuO₄(OH)₂]·3H₂O (II) were prepared as single crystals and examined by X-ray diffraction. The compounds are isostructural and crystallize in the monoclinic system, space group C2/c, Z = 4; unit cell parameters: a = 12.1544(3), b = 10.9942(2), c = 7.789(2) ?, ?? = 91.0930(11)° for I and a = 12.1254(3), b = 10.9506(2), c = 7.7699(2) ?, ?? = 90.8253(12)° for II. The main structural elements of I and II are centrosymmetrical anions [AnO₄(OH)₂]^3? forming together with water molecules, owing to strong hydrogen bonding, chains oriented along [101]. In [AnO₄(OH)₂]^3? anions, the central An(VII) atom has a tetragonal-bipyramidal oxygen surrounding. The An-O(OH) interatomic distances decrease in going from I to II owing to actinide contraction by a factor of ??2 more strongly than the An-O bond lengths in the equatorial planes of the bipyramids. The previously studied structure of Cs₃[NpO₄(OH)₂]·3H₂O (III) was refined.     

Reaction of Cd(NO3)2·4H2O with 4,4'–bipyridine (bpy) in MeOH solvent: synthesis and characterization of T-shaped [Cd(bpy)1.5(NO3)2]·3H2O,square grid [Cd(bpy)2(H2O)2](NO3)2·4H2O and linear polymeric [Cd(bpy)(H2O)2(NO3)2]

The influence of concentration of water and metal salt in the reaction between Cd(NO₃)₂·4H₂O and 4,4′–bipyridine in MeOH has been studied and three compounds namely, T-shaped [Cd(bpy)_1.5(NO₃)₂]·3H₂O, 1 square grid [Cd(bpy)₂(H₂O)₂](NO₃)₂ 4H₂O, 2 and one dimensional linear polymer, [Cd(bpy)(H₂O)₂(NO₃)₂], 3 were isolated quantitatively in this process. Compound 1 forms in MeOH at high dilution of the metal salt (5.0 mg/mL or less) and for the metal-to-ligand ratio 1:(1.5–2.0). Compound 2 forms exclusively in the concentration range, 17–33% for water in MeOH by volume and 12–28 mg/mL for the metal salt of the solution. Outside these limits, mixtures of 2 and 3 were isolated. For 1:1 ratio of metal salt to bpy, the linear polymer, 3 was obtained in major quantity and its formation was found to be independent of concentration of water or the metal salt. Compounds 1 and 2 have been characterized by X-ray crystallography. On heating all the compounds decompose through a common intermediate [Cd(bpy)(NO₃)₂] and finally to CdO as monitored by TG.     

Photocatalytic Properties of the MgHPO4·3H2O and MgKPO4·6H2O Phosphates

Inorganic Materials - Magnesium double phosphates, MgHPO4·3H2O and MgKPO4·6H2O, isostructural with the minerals newberyite and struvite-K have been synthesized in powder form via...     

Framework materials containing polyoxovanadates as building units: synthesis and characterization of (N2H5)2[M3(H2O)12V18O42(EO4)]·24H2O (M = Mg,Ca) and Li6[Mn3(H2O)12V18O42(EO4)]·24H2O (E = V,S)

The reaction of an aqueous solution of lithium vanadate with hydrazinium sulfate results in a dark-colored solution that reacts with magnesium sulfate heptahydrate, calcium sulfate dihydrate, and manganese(II) chloride tetrahydrate to yield single crystals of (N₂H₅)₂[M₃(H₂O)₁₂V₁₈O₄₂(EO₄)]·24H₂O (M = Mg, Ca) and Li₆[Mn₃(H₂O)₁₂V₁₈O₄₂(EO₄)]·24H₂O (E = V, S), respectively. The crystal structures of the new solids consist of interpenetrating three-dimensional networks of {V₁₈O₄₂(EO₄)} clusters interlinked via bridging {M(H₂O)₄} (M = Mg, Ca, Mn) groups. The voids in these structures are occupied by lattice water and ion exchangeable cations.     

Synthesis and crystal structure of a new Np(V) oxalate, Na4(NpO2)2(C2O4)3·6H2O

A new oxalate complex, Na₄(NpO₂)₂(C₂O₄)₃·6H₂O, with the Np:C₂O₄ ratio of 2:3 was synthesized and studied by single crystal X-ray diffraction. In the crystal, the NpO ₂ ⁺ cations and oxalate anions are bound in open networks [(NpO₂)₂(C₂O₄)₃] _n ^4n- parallel to the bc plane. The Na(1) cations are accommodated in large voids of the neptunyl oxalate networks with the formation of crimped mixed-cation layers of the composition [Na₂(NpO₂)₂(C₂O₄)₃] _n ^2n- . The negative charge of the layers is compensated by the Na(2) cations arranged between the layers. The Np atoms have a pentagonal bipyramidal coordination surrounding with the equatorial plane formed by the oxygen atoms of three oxalate anions. The structure contains tridentate-bridging and tetradentate-bridging oxalate anions.     

A single crystal X-ray diffraction study of Na4(UO2)4(i-C4H9COO)11(NO3)·3H2O

Synthesis and the results of IR and single crystal X-ray diffraction study of Na₄(UO₂)₄(i-C₄H₉COO)₁₁·(NO₃)·3H₂O are reported. The crystals are monoclinic; the unit cell parameters at 100 K are as follows: a = 13.697(2), b = 20.285(3), c = 15.991(3) Å, β = 103.760(3)°, space group P2₁, Z = 2, R = 0.0650. The uraniumcontaining structural units are mononuclear moieties [UO₂(i-C₄H₉COO)₃]^? and [UO₂(NO₃)(i-C₄H₉COO)₂]^?, belonging to crystal-chemical group AB ₃ ⁰¹ (A = UO ₂ ²⁺ , B⁰¹ = i-C₄H₉COO^? and NO ₃ ^? ) of uranyl complexes. The IR data are consistent with the results of the single crystal X-ray diffraction study. The influence of the carboxylate ligand volume on the structure of Na[UO₂L₃]·nH₂O crystals (L = acetate, n-butyrate, isovalerate ion) is analyzed.     

Thermal properties and radiation damage in NaNH4XO4·2H2O single crystals (XO4=SO4,SeO4)

Differential thermal analysis (DTA) studies of NaNH₄SO₄·2H₂O, NaND₄SO₄·2H₂O, and NaNH₄SeO₄·2H₂O single crystals were performed in the temperature range of the ferroelectric-paraelectric phase transition and of the dehydration process. The first-order phase transition at the Curie point was confirmed for NaNH₄SO₄·2H₂O, whereas the transition in the isomorphous NaNH₄SeO₄·2H₂O at the Curie temperature was found to be similar to a contineous (second order) with considerable higher transition enthalpy. Dehydration process of the crystals studied was found to proceed in two stages, with maximum dehydration rates at 355 and 400K. A linear decrease in thermal energy related to the long-range ordering in NaNH₄SO₄·2H₂O crystals was observed with the dose of -cobalt-60 irradiation and discussed with respect to the radiation induced decrease in spontaneous polarization.     

Synthesis,Characterization, and X-ray Structure of Tetraaminoguanidinium Diuranyl Tetraoxalate Monohydrate (HAgun)4[(UO2)2(C2O4)4]·H2O

Radiochemistry - A new uranyl oxalate complex containing aminoguanidinium cation was isolated from an aqueous solution containing uranyl nitrate hexahydrate, oxalic acid dihydrate, and...     

Complexes with substituted 2,5-dihydroxy-p-benzoquinones: AE[C6(C2H5)2O4]·3H2O (AE=Ca,Sr, Ba)

Single crystals of AE[C₆(C₂H₅)₂O₄]·3H₂O belonging to space group P2₁2₁2₁ were grown in aqueous silicagel (AE=Ca, Sr) and in aqueous solution (AE=Ba), respectively. AE²⁺ is coordinated by four oxygen atoms of two bis-chelating [C₆(C₂H₅)₂O₄]²⁻ ions, thus forming infinite, corrugated chains extending along [010]. The coordination polyhedron is completed by additional water molecules. The coordination sphere is different for the three different AE²⁺ ions yielding CN increasing from Ca²⁺ to Ba²⁺. The principle features of the crystal structure, however, remain unchanged. Adjacent chains are interlinked by hydrogen bonds between water molecules of the coordination sphere and the oxygen atoms of the [C₆(C₂H₅)₂O₄]²⁻ ion.