Evaluation of water sorption property and in vitro blood compatibility of poly(2-hydroxyethyl methacrylate) (PHEMA) based semi interpenetrating polymer networks (IPNs)

pH responsive smart biomaterials of gelatin and poly(2-hydroxyethyl methacrylate-co-acrylic acid) were synthesized by redox polymerization and characterized by FTIR, Environmental Scanning Electron Microscopy (ESEM). The prepared environmental responsive biomaterials containing polyelectrolyte segments were assessed for their water sorption potential under varying experimental conditions. The diffusion mechanism of transport of water molecules arising due to solvent-polymer interaction was also analysed to predict the behaviour of continuously relaxing macromolecular chains. The in vitro blood compatibility of the prepared polymeric hydrophilic materials was evaluated by methods such as blood clot formation, platelet adhesion, percent haemolysis and protein-adsorption study on the surface of the prepared biomaterials.     

Comparison of cefpodoxime proxetil release and antimicrobial activity from tablet formulations: complexation with hydroxypropyl-β-cyclodextrin in the presence of water soluble polymer

This study aims to prove the complexation of cefpodoxime proxetil (CP) by hydroxypropyl-β-cyclodextrin (HP-β-CD) in the presence of sodium carboxymethyl cellulose (Na CMC), and makes a comparison of commercial tablets by dissolution and antimicrobial activity studies. The CP--HP-β-CD complex was prepared by kneading method and characterized by SEM, FTIR and DSC. The solubility method was used to investigate the effect of HP-β-CD and Na CMC on the solubility of CP. The complex tablets were prepared using direct compression method. Dissolution studies were performed with complex tablets and commercial tablets in pH 1.2, 4.5, 6.8 and 7.4 buffer solutions. It was observed that complexation occurred in all formulations, and HP-β-CD is able to increase CP solubility and dissolution rate of CP was improved from complex tablets, when compared with commercial tablets. Furthermore, the antimicrobial activity studies revealed that the CP--HP-β-CD complex and complex tablets were shown to have more effective antimicrobial activity than commercial tablets. It is evident from the results that complexation with HP-β-CD in the presence of Na CMC is feasible way to prepare a more efficient tablet formulation with improved dissolution and antimicrobial activity.     

Localization of U(VI) on nickel hydroxide from aqueous solution in the presence of complexing anions at 25°C

Sorption and coprecipitation of U(VI) from aqueous solution containing various complexing anions (CO₃^25-, SO₄²⁻, H₂EDTA²⁻) with the Ni(OH)₂ solid phase at 25°C was studied. Uranium(VI) is not noticeably sorbed on the Ni(OH)₂ solid phase from aqueous solutions containing CO₃²⁻ and SO₄²⁻. The distribution coefficients K _d are less than 1.0 ml g⁻¹ throughout the examined range of [U(VI)]: [L] ratios (L = CO₃²⁻, SO₄²⁻) at V/m ≥ 100 ml g⁻¹ and contact time of the solid and liquid phases of 60 min. In the presence and in the absence of H₂EDTA²⁻, the degree of the U(VI) sorption is essentially the same (K _d ∼90–140 ml g⁻¹ at V/m ≥ 100 ml g⁻¹). Uranium(VI) does not coprecipitate with Ni(OH)₂ from aqueous solutions containing SO₄²⁻ and H₂EDTA²⁻. The distribution coefficients K _d are less than 0.001 ml g⁻¹ at V/m ≥ 200 ml g⁻¹ and contact time of the solid and liquid phases of 60 min. In solutions containing CO₃²⁻, the U(VI) capture by the Ni(OH)₂ precipitate depends on the [CO₃²⁻]: [U(VI)] ratio. The higher the [CO₃²⁻]: [U(VI)] ratio, the more strongly U(VI) coprecipitates with Ni(OH)₂.     

An investigation about thin films of poly[2-methoxy-5-(2′-ethyl-hexyloxy) phenylene vinylene] (MEH-PPV) prepared by Langmuir-Schaefer technique

The Langmuir monolayer behaviour of poly[(2-methoxy-5-(2-ethyl-hexyloxy) phenylene vinylene] (MEH-PPV) conducting polymer was investigated at air-water interface at different subphases containing anions. A uniform deposition of MEH-PPV monolayers was shown by UV-visible, electrochemical techniques, where the influence of anions on redox properties was investigated by cyclic voltammetric surveying. The nature of anions revealed significant changes in redox properties of the MEH-PPV LS films. The photoelectrochemical response of MEH-PPV LS conducting polymer was also investigated at length.     

Asymmetric Synthesis of L-[β-11C]-3,4-Dihydroxyphenylalanine via the Chiral Ni(II) Complex of the Schiff Base Derived from (S)-o-N-(N'-Benzylprolyl)aminobenzophenone and Glycine (Ni-BPB-Gly)

A procedure was proposed for asymmetric synthesis of L-[-¹¹C]-3,4-dihydroxyphenylalanine (L-[-¹¹C]DOPA), which is a radiotracer used for estimating the density of dopaminergic neurons by positron emission tomography (PET). The procedure involves the use of a new chiral inductor, the nickel complex of the Schiff base derived from (S)-o-N-(N'-benzylprolyl)aminobenzophenone and glycine (Ni-BPB-Gly). The reaction of the asymmetric inductor Ni-BPB-Gly with [-¹¹C]-3,4-dimethoxybenzyl bromide in the presence of potassium tert-butylate was performed in acetone at 80°C for 5 min. Decomposition of the resulting diastereomeric complex with 6 M HCl, followed by demethylation of hydroxy groups with concentrated HI, yielded L-DOPA. The radiochemical yield corrected for the ¹¹C decay was 2-16% at the synthesis time of 60-66 min (with an RB-86 robotic system, Anatech). The enantiomeric excess (ee) of L-[-¹¹C]DOPA varied within 60-98%. The possibility of asymmetric synthesis of L-[-¹¹C]DOPA was demonstrated for the first time; however, the procedure requires further optimization.     

Thermal behavior of α-Ba(FeS2)2 and AgFeS2: quasi-unidimensional and 3D network compounds prepared from ion-exchange on the same precursor

Thermal behavior of AgFeS₂ and -Ba(FeS₂)₂ were studied under air atmosphere. Decomposition products of AgFeS₂ are Ag₂S, FeS₂ (pyrite form), Ag₂SO₄, -Fe₂O₃ and metallic silver. -Ba(FeS₂)₂ decomposes to pyrite, -Fe₂O₃ and BaSO₄. We propose that metallic sulfide formation on the initial step of the decomposition of these compounds is related to the packing of the metallic ions with sulfur and, hence, with metal-sulfur distances in the original material. Morphological information about AgFeS₂ and -Ba(FeS₂)₂ are presented for the first time.     

Interpenetrating covalent and noncovalent nets in the crystal structures of [M(4,4′-bipyridine)2(NO3)2]·3C10H8 (M = Co,Ni)

The synthesis and crystal structures of [M(4,4′-bipyridine)₂(NO₃)₂]·3naphthalene (M = Co, 1·3naphthalene; Ni, 2·3naphthalene) are reported. 1·3naphthalene and 2·3naphthalene are isostructural and represent rare examples of interpenetrating planar networks that are chemically and topologically different. It appears that the networks coexist because the (4,4) topology of the cobalt and nickel square grids is complementary to the (6,3) topology of the naphthalene honeycomb network, resulting in an inclined interpenetrated 3D architecture. This observation is discussed in the context of rational design strategies for hybrid solids.     

Hydrothermal Crystallization in the Systems LiOH–MO2–GeO2–H2O (M = Ti, Sn) at 500°C and 0.1 GPa: Li2Ti[5]Ge[4]O5 and Li2Ge[6]Ge2 [4]O6 Phase Relations

Crystallization in the LiH–Ti₂–Ge₂–H₂O and LiOH–SnO₂–GeO₂–H₂O hydrothermal systems was studied at 500°C and 0.1 GPa. The phases crystallizing in the Ti system are Li₂Ti^[5]Ge^[4]O₅, Li₂Ge^[6]Ge₂ ^[4]O₆(OH)₂, Li₃HGe₄ ^[6]Ge₃ ^[4]O₁₆ · 4H₂O, and Li₂Ge^[4]O₃ (Ge in four- or sixfold oxygen coordination, and Ti in fivefold oxygen coordination). Over a wide range of TiO₂ : GeO₂ molar ratios (6 : 1 to 1 : 1), the dominant phase is Li₂Ge^[6]Ge₂ ^[4]O₆(OH)₂. At higher GeO₂ contents (TiO₂ : GeO₂ = 1 : 2 to 1 : 6), both Li₂Ti^[5]Ge^[4]O₅ and Li₂Ge^[6]Ge₂ ^[4]O₆(OH)₂ crystallize. The crystallization fields of Ge-containing phases at TiO₂ : GeO₂ = 1 : 2 to 1 : 6 are (in order of increasing LiOH concentration) GeO₂ (rutile structure), Li₂Ti^[5]Ge^[4]O₅ + Li₂Ge^[6]Ge₂ ^[4]O₆(OH)₂, and Li₂Ti^[5]Ge^[4]O₅ + Li₂Ge^[6]Ge₂ ^[4]O₆(OH)₂ + Li₂Ge^[4]₃ + Li₃HGe₄ ^[6]Ge₃ ^[4]O₁₆ · 4H₂O. The phases crystallizing in the Sn system are Li₂Ge^[6]Ge₂ ^[4]O₆(OH)₂, Li₃HGe₄ ^[6]Ge₃ ^[4]O₁₆ · 4H₂O, and Li₂Ge^[4]O₃. Tin is present in the form of SnO₂ only. The structures of Li₂Ti^[5]Ge^[4]O₅ and Li₂Ge^[6]Ge₂ ^[4]O₆(OH)₂ are characterized by the simplest type of matrix assembly: direct packing of substructural precursor units and their two-dimensional growth in various crystallographic directions.     

Interaction of An(VI) (An = U, Np, Pu) and Np(V) with 2,3-pyridinedicarboxylic (quinolinic) acid (H2Quin): Complexation in aqueous solutions, synthesis and structure of the complexes [UO2(HQuin)2], [(NpO2)2(HQuin)2(C6H4NO3)2]·2H2O, and [PuO2Quin(H2O)]

Complexation of An(VI) (An = U, Np, Pu), and Np(V) with 2,3-pyridinedicarboxylic (quinolinic, H₂Quin) acid in aqueous solutions was studied. Np(V) can form 1: 1 and 1: 2 complexes, and An(VI), also 1: 3 complexes (at pH ? 6 and [H₂Quin] ? 0.1 M). Quinolinate ion can coordinate to actinide(VI) and (V) ions in solutions in different modes. The apparent stability constants of the complexes in a wide pH range and the concentration stability constants of the An(VI) complexes were measured. In the series from Pu(VI) to U(VI), the stability of the complexes slightly increases. Crystalline complexes [UO₂(HQuin)₂], [(NpO₂)₂(HQuin)₂(HL)₂]·2H₂O (HL is N-protonated 2-hydroxypyridine-3-carboxylic acid anion), and [PuO₂Quin(H₂O)] were synthesized, and their structures were determined by single crystal X-ray diffraction. Different types of coordination of quinolinate ions to actinide ions are also observed in the crystalline complexes.     

Pinning of Vortices Nearly Parallel to the Superconducting Plane in κ-(ET)2Cu[N(CN)2]Br and κ-(ET)2Cu(NCS)2

The vortex state under a magnetic field applied nearly parallel to the superconducting plane has been studied by means of an ac susceptibility measurement around 2 MHz in the organic superconductors -(ET)₂Cu[N(CN)₂]Br and -(ET)₂Cu(NCS)₂. The diamagnetic response, due to pinning of the staircase vortices for the inclined field, was suppressed by the increase in the magnetic field. This finding indicates that the parallel vortices become freely movable as a result of either decoupling between layers or depinning of Abrikosov vortices in the layer plane. We found that the suppression of the diamagnetic response was promoted by the parallel field component.     

Cross-slip on the first order pyramidal plane (10\bar 11) of a-type dislocations [1\bar 210] in the plastic deformation of α-titanium single crystals

The nature of the cross-slip plane was determined by electron microscopy observations of α-titanium single crystal specimens, oriented for single prismatic slip (10 \(\bar 1\) 0) [1 \(\bar 2\) 10]. The occurrence of cross slip on the first order pyramidal plane (10 \(\bar 1\) 1) was proved for a-type dislocations [1 \(\bar 2\) 10]. Furthermore, two types of dislocation configuration due to the double cross-slip were observed: edge dislocation dipoles and loops elongated along the Burger's vector.     

Complexation of hexavalent U,Np, and Pu with cyclopropanecarboxylate anions. Crystal structure of the uranyl complexes {[UO2(bipy)(cpc)]2O2} and [UO2(cpc)2(H2O)2] (bipy = 2,2′-Bipyridine,cpc− = cyclopropanecarboxylate anion)

The complexation of hexavalent U, Np, and Pu with cyclopropanecarboxylate anions, cpc^?, in aqueous solutions was studied. The stepwise concentration stability constants of the complexes PuO₂(cpc) _i ^2?i (i = 1, 2, 3) are as follows: logK _1,2,3 = 2.63 ± 0.20, 1.61 ± 0.20, 1.43 ± 0.20, respectively; the overall concentration stability constant of the complex PuO₂(cpc) ₃ ^? is logβ₃ = 5.67 ± 0.60. The complexing properties of the cpc^? anion are very close to those of butyrate and isobutyrate anions. Two crystalline uranyl compounds were synthesized: {[UO₂(bipy)(cpc)]₂O₂} (bipy = 2,2′-bipyridine) and [UO₂(cpc)₂(H₂O)₂]. The specific feature of the first complex is that it contains peroxide ion. Its appearance may be due to the formation of the cationic moiety via hydrolytic uranyl dimer. The second compound forms a 3D structure, with the complexes linked via hydrogen bonds.     

Competition between superconductivity and insulating magnetic state in κ-(BEDT-TTF)2Cu[N(CN)2]Cl: Effects of pressure, magnetic field, and partial anion substitution

Systematic experimental study of the electrical transport and static magnetization reveals a direct and delicate interplay between magnetism and superconductivity in the organic material-(BEDT-TTF)₂Cu[N(CN)₂]Cl, displayed through the specific temperature-pressure phase diagram, and such new effects for organic solids as the reentrant superconductivity in zero applied magnetic field and high-field-induced interchange between superconductivity and the nonmetallic resistive phase in the high-pressure region.