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At least 775 records · Page 43Linked to original sources
PubMed2005

Conformational analysis and crystal structure of {[1-(3-chloro-4-fluorobenzoyl)-4-fluoropiperidin-4yl]methyl}[(5-methylpyridin-2-yl)methyl]amine, fumaric acid salt.

{[1-(3-Chloro-4-fluorobenzoyl)-4-fluoropiperidin-4yl]methyl}[(5-methylpyridin-2-yl)methyl]amine, fumaric acid salt (C(20)H(22)ClF(2)N(3)O, C(4)H(4)O(4)) (1) was synthesized and characterized by the complete (1)H, (13)C and (19)F NMR analyses. The conformation of the piperidin ring, in the solution state, was particularly studied from the coupling constants determined by recording a double-quantum filtered COSY experiment in phase-sensitive mode. (1)H NMR line-shape analysis was used, at temperatures varying between -5 and +60 degrees C, to determine the enthalpy of activation of the rotational barrier around the CN bond. Compound 1 crystallizes in the triclinic space group P1 with a=8.517(3) Angstrom, b=12.384(2) Angstrom, c=12.472(3) Angstrom, alpha=70.88(2) degrees, beta=82.04(2) degrees, gamma=83.58(2) degrees. The results strongly indicate that the solid and solution conformations are similar. Thermal stability and phases transitions were investigated by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Furthermore polymorphism screening was studied from recrystallization of 1 performed in seven solvents and by slurry conversion in water. The X-ray powder diffraction (XRPD) and differential scanning calorimetry results suggested that 1 crystallizes into one crystalline form which melts at 157 degrees C (DeltaH=132 J g(-1)).

Calorimetry, Differential Scanning↗
PubMed2005

Yb3+ as an origin of the strong anti-Stokes luminescence in NIR FT-Raman spectra of some lanthanide sesquioxides.

Strong anti-Stokes bands observed in FT-Raman spectra of Y2O3, Gd2O3 and Lu2O3 are explained by NIR luminescence of Yb3+ impurities present in sesquioxides after the excitation with the 1064 nm line of an Nd:YAG laser. Samples of Y2O3:Yb, Ga2O3:Yb, CeO2:Yb, Gd2O3:Yb and Lu2O3:Yb were prepared by solution combustion synthesis procedure using urea. All materials were investigated by FT-Raman and FT-NIR spectroscopy and characterized by X-ray powder diffraction.

Lanthanoid Series Elements↗
PubMed2006

Determinations of the inclusion complex between gossypol and beta-cyclodextrin.

Features of the inclusion complex between gossypol (Gos) and beta-cyclodextrin (CD), such as its aqueous solubility, association constant, characteristics in the solid state and crystalline morphology, as well as the stoichiometry of this complex have been determined. The phase-solubility diagram drawn using UV detections belongs to an AN-type. Fluorescence detection and calculation with the modified Benesi-Hidebrond equation provide an 1:2 stoichiometry for the complex. Its apparent stability constant has been determined to be 3,203 M(-1) by fluorescence technique and confirmed by the calculation from UV spectroscopy. X-ray powder diffractions (XRD) and Scanning Electron Microscopy (SEM) observations showed a clear difference in the crystal morphology of the complex from those of both Gos and beta-CD.

Cyclodextrins↗
PubMed2006

Mononuclear metal complexes of organic carboxylic acid derivatives: synthesis, spectroscopic characterization, thermal investigation and antimicrobial activity.

Two Schiff base ligands bearing organic acid moiety, vis., N-(2-thienylmethylidene)-2-amino-4-chlorobenzoic acid (HL(1)) and N-(2-hydroxybenzylidene)-2-amino-4-chlorobenzoic acid (H(2)L(2)) have been synthesized by the interaction of 2-thiophenecarboxaldehyde and 2-hydroxybenzaldehyde with 2-amino-4-chlorobenzoic acid. Co(II), Ni(II), Cu(II) and Zn(II) complexes of these ligands have been prepared. They are characterized on the basis of analytical data, molar conductance, IR, (1)H NMR, UV-vis, mass spectra, magnetic measurements, thermal analysis and X-ray powder diffraction technique. The molar conductance data reveal that these complexes are non-electrolytes. The ligands are coordinated to the metal ions in a terdentate manner with ONO/ONS donor sites of the carbonyl oxygen, azomethine nitrogen and phenolic oxygen or thiophenic sulphur. An octahedral structure is proposed for the prepared metal complexes and some ligand field parameters (D(q), B and beta) in addition to CFSE were calculated. The thermal stability of the metal complexes is evaluated. The Schiff base ligands and their metal complexes have been tested against four species of bacteria as well as four species of fungi and the results have been compared with some known antibiotics.

Carboxylic Acids↗
PubMed2006

Nickel(II) complexes of biologically active glutathione: spectroscopic, kinetics of thermal decomposition and XRPD studies.

Nickel(II) complexes of reduced glutathione (GSH) of general composition Na[Ni(L)(X)]H(2)O, where H(2)L=GSH; X=NO(3)(-), SCN(-), CH(3)CO(2)(-), Cl(-) have been synthesized and characterized by elemental analysis, infrared spectra, electronic spectra, magnetic susceptibility measurements, thermal and X-ray powder diffraction studies. Infrared spectra indicate deprotonation and coordination of cysteinyl sulphur and carboxylate oxygen of glycine residue with nickel ions. It indicates the presence of water molecule in all the complexes which has been supported by TG/DTA. The thermal behavior of complexes shows that water molecule is removed in first step-followed removal of anions and then decomposition of the ligand molecule in subsequent steps. General mechanisms describing the decomposition of the solid complexes are suggested. Kinetic and thermodynamic parameters were computed from the thermal decomposition data. The room temperature magnetic moment values for all the complexes lie in the range of 2.2-2.4BM, indicating departure from spin only values due to second order Zeeman effect. The electronic spectra indicate planar coordination geometry for all the complexes. Crystal data for Na[Ni(L)(CH(3)CO(2)(-))]H(2)O: tetragonal, space group P4/m, a=8.2004A, b=8.2004A, c=16.0226A, V=1077.47A(3), Z=2. Crystal data for Na[Ni(L)(Cl(-))]H(2)O: cubic, space group Pm3, a=16.1055A, b=16.1055A, c=16.1055A, V=4178.38A(3), Z=6. Crystal data for Na[Ni(L)(NO(3)(-))]H(2)O: tetragonal, space group P4/m, a=7.2121A, b=7.2121A, c=12.0200A, V=625.22A(3), Z=2.

Electron Probe Microanalysis↗
PubMed2006

Reaction of layered sodium disilicate SKS-6 with calcium chloride solution as revealed by solid state NMR spectroscopy: exploring the calcium ion extracting mechanism of SKS-6.

Solid-state 1H, 29Si NMR and 23Na MQMAS NMR spectroscopy combined with X-ray powder diffraction (XRD) technique was used to study the reaction between layered sodium disilicate SKS-6 and calcium chloride solution with different concentrations. Based on the experimental results the calcium ion extracting mechanism of SKS-6 was demonstrated to be via ion replacement, during which calcium ions replace sodium ions and combine with the non-bridging oxygen in SKS-6 for charge compensation, and simultaneously sodium ions leave the interlayer. This ion-replacement process was greatly influenced by the substitution of sodium ions by protons as well as the calcium ions concentration. Increasing calcium ions concentration favors the replacement of sodium ions by calcium ions, but prevents sodium ions from being substituted by protons.

Journal Article↗
PubMed2004

A sonochemical method for the selective synthesis of alpha-HgS and beta-HgS nanoparticles.

A novel sonochemical method for the selective synthesis of alpha-HgS (cinnabar) and beta-HgS (metacinnabar) nanoparticles in aqueous solutions is reported in this paper. alpha-HgS and beta-HgS nanoparticles have been selectively prepared by choosing sodium thiosulfate and thiourea as the sulfur source respectively. To study the crystalline structure, size, morphology and composition of the products, characterization techniques including X-ray powder diffraction, transmission electron microscopy, selected area electron diffraction, X-ray photoelectron spectroscopy and energy-dispersive X-ray analysis are employed. The optical properties of the nanoparticles are investigated by UV-visible absorption spectroscopic measurements. The direct band gap of the as-prepared alpha-HgS nanoparticles with an average size of 12 nm is calculated to be 2.8 eV according to the absorption spectrum. In the case of the beta-HgS nanoparticles with an average size of 13 nm, a broad absorption peak is observed in the UV-visible absorption spectrum, which can be ascribed to the special surface state of this sample. Probable mechanisms for the sonochemical formation of alpha-HgS and beta-HgS nanoparticles in aqueous solutions are presented. The optimum pH value of the stock solutions and the effect of sonication time on the particle size are also investigated.

Journal Article↗
PubMed2006

Ultrasonic-assisted size-controllable synthesis of Bi2Te3 nanoflakes with electrogenerated chemiluminescence.

Bi(2)Te(3) hexagonal nanoflakes with controllable edge length ranging from approximately 150 nm to as small as approximately 10nm were synthesized via an ultrasonic-assisted disproportionation route, using Te powder and Bi(NO(3))(3).5H(2)O as raw materials. The mechanochemical effects of the ultrasonic irradiation accelerated the reaction and were helpful to obtain relatively small and uniform nanocrystals. The products were characterized by X-ray powder diffraction, X-ray photoelectron spectra, transmission electron microscopy, and selected area electron diffraction techniques. Electrogenerated chemiluminescence of as-prepared Bi(2)Te(3) was also reported for the first time.

Journal Article↗
PubMed2006

Synthesis of Pt modified ZSM-5 and beta zeolite catalysts: influence of ultrasonic irradiation and preparation methods on physico-chemical and catalytic properties in pentane isomerization.

Influence of preparation methods and ultrasound irradiation on physico-chemical and catalytic properties was investigated by synthesizing Pt-ZSM-5 and Pt-Beta catalysts by in-situ and impregnation methods and applying ultrasound irradiation to synthesis gel mixture of ZSM-5 and Beta zeolites. It was concluded from the X-ray powder diffraction patterns of Pt-ZSM-5 and Pt-Beta zeolite catalysts that introduction of Pt by in-situ method and ultrasound irradiation did not influence the structures of ZSM-5 and Beta zeolites. Morphology of ZSM-5 and Beta zeolites were investigated by scanning electron microscopy. SEM micrographs showed that the Pt-ZSM-5-IS-US catalyst synthesized by in-situ method with ultrasound irradiation resulted in smaller crystals of ZSM-5 than Pt-ZSM-5-IS catalyst prepared without ultrasound irradiation. Furthermore SEM micrographs of Pt-Beta-11-IS-US zeolite synthesized using ultrasound irradiation showed much smaller crystals than Pt-Beta-11-IM indicating that ultrasound irradiation had a significant effect on the morphology of Beta zeolite. Conversion of n-pentane and selectivity to iso-pentane over the Pt-ZSM-5-IS-US zeolite catalysts prepared by ultrasound irradiation during in-situ introduction of platinum was higher than the catalysts prepared without the ultrasound irradiation. Furthermore ultrasound irradiated and in-situ synthesized Pt-Beta-11-IS-US catalyst also showed higher selectivity to iso-pentane than Pt-H-Beta-11-IM prepared by impregnation method.

Journal Article↗
PubMed2006

Submicrocubes and highly oriented assemblies of MnCO3 synthesized by ultrasound agitation method and their thermal transformation to nanoporous Mn2O3.

MnCO(3) submicrocubes and highly oriented MnCO(3) nanocrystal assemblies with an ellipsoidal morphology have been successfully prepared by an ultrasonic solution approach. The effect of surfactants of sodium dodecylsulfate (SDS) and aerosol OT (AOT) on the morphology of MnCO(3) was investigated. Highly oriented ellipsoidal assemblies composed of approximately 5 nm MnCO(3) nanocrystals with porous nanostructures were prepared in the presence of SDS. Both sonochemical irradiation and surfactant play an important role in the formation of these highly oriented assemblies. Nanoporous Mn(2)O(3) was obtained by thermal treatment of MnCO(3) at 600 degrees C in air. The shape of MnCO(3) was sustained after thermal transformation to form nanoporous Mn(2)O(3). The products were characterized by X-ray powder diffraction, transmission electron microscopy, selected-area electron diffraction, field emission scanning electron microscopy, thermogravimetric analysis and differential scanning calorimetric analysis.

Journal Article↗
PubMed2006

Chemical and physical characterization of electrode materials of spent sealed Ni-Cd batteries.

The present work aimed at the chemical and physical characterization of spent sealed MONO-type Ni-Cd batteries, contributing to a better definition of the recycling process of these spent products. The electrode material containing essentially nickel, cadmium and some cobalt corresponds to approximately 49% of the weight of the batteries. The remaining components are the steel parts from the external case and the supporting grids (40%) containing Fe and Ni, the electrolyte (9%) and the plastic components (2%). Elemental quantitative analysis showed that the electrodes are highly concentrated in metals. The phase identification achieved by X-ray powder diffraction combined with chemical analysis and leaching tests allowed the authors to proceed with the composition of the electrode materials as following: cathode: 28.7% metallic Ni, 53.3% Ni(OH)2, 6.8% Cd(OH)2 and 2.8% Co(OH)2; anode: 39.4% metallic Ni and 57.0% Cd(OH)2. The morphology of the electrodes was studied by microscopic techniques and two phases were observed in the electrodes: (1) a bright metallic phase constituted of small nickel grains that acts as conductor, and (2) the main hydroxide phase of the active electrodes into which the nickel grains are dispersed. The disaggregation of the electrode particles from the supporting plates was easily obtained during the dismantling procedures, indicating that a substantial percentage of the electrodes can be efficiently separated by wet sieving after shredding the spent batteries.

Cadmium↗
PubMed2000

Crystallographic analysis of demineralized human enamel treated by laser-irradiation or remineralization.

Crystallographic information on dental hard tissue is helpful in evaluating whether incipient caries that has received preventative treatments is resistant to subsequent attack. The aim here was to analyse crystallographically by means of high-resolution electron microscopy (HREM) demineralized human enamel that had been laser-irradiated or remineralized. Electron-microscopic observation identified a distinct layer at a depth of 100 nm in the demineralized and laser-irradiated enamel. The crystallinity in the shallower area was inferior to that in the deeper area. Comparison of the HREM findings from the deeper area with the data provided by the Joint Committee on Powdered Diffraction Standards revealed that the mineral in the demineralized and laser-irradiated enamel was either alpha- or beta-tricalcium phosphate, while that in the remineralized enamel was thought to be tetracalcium diphosphate monoxide.

Adolescent↗
PubMedDate not supplied

Presence of calcified tissue in the human temporomandibular joint disc.

Large calcified areas were observed in the articular discs of the temporomandibular joint from five patients suffering from articular dysfunctions. The calcified regions were always located inside the fibrous tissue of the discs. They had a woven bone-like morphological pattern and consisted of a compact mineralized tissue containing cells in irregular lacunae. In all the samples the calcified tissue was completely surrounded by a mineralizing border rich in cells and variously arranged collagen fibrils. Energy-dispersive spectrometry showed that mineralized regions contained large amounts of Ca and P. X-ray powder diffraction identified the crystals in these areas as hydroxyapatite.

Bone and Bones↗
PubMed2002

Propionic acid side chain hydrogen bonding in the malaria pigment beta-hematin.

Malaria pigment, or beta-hematin, the insoluble heme detoxification product resulting from the intraerythrocitic digestion of hemoglobin by young malaria trophozoites has been structurally characterized by X-ray powder diffraction and shown to contain chains of propionic acid linked dimers. Although there is considerable spectroscopic evidence for a monodentate propionate-iron interaction in this crystalline material, the spectroscopic characterization of the propionic acid dimer is limited. Herein we demonstrate the presence of the propionic acid dimer unit by H/D isotope substitution in carboxylic acid dimer. In the Raman spectrum of the deuterium substituted compound there is a circa 12 cm(-1) shift, H: 1629 cm(-1) vs. D: 1617 cm(-1) in the symmetric ring breathing mode for the propionic acid dimer. On the other hand, the IR active asymmetric stretch has a very small shift, <3 cm(-1), upon deuteration. These, and other vibrational data, are consistent with the presence of a planar carboxylic acid dimer in the structure of beta-hematin.

Animals↗
PubMed1976

Paget's osteitis deformans: a carbonate-rich calcium alkali phosphate in the pre-malignant bone mineral and implications for lymphoma production by CO2.

Comparison of powder diffraction patterns of unheated normal bone mineral with the damaged by Paget's Osteitis Deformans showed that due to a difference in the spacing of one weak inner reflection the possibility exists that carbonate-containing alpha-calcium sodium orthophosphate may be a minor constituent of the osteitic bone mineral. The chemical and physical properties of this substance make it a likely minor constituent of bone salt. The presence of this calcium alkali phosphate in the osteitic mineral was tentatively proposed after demonstrating the similarity of the diffraction patterns of synthetic mixtures of this substance with tricalcium phosphate hydrate to those of the osteitic bone salt.

Aged↗
PubMed2002

Hydroxyapatite and calcium phosphate coatings on aluminium oxide orbital implants.

BACKGROUND: Hydroxyapatite and calcium phosphate have been used as bone graft substitutes as they facilitate and promote tissue ingrowth. We carried out a study to examine uncoated and coated aluminium oxide (alumina) spherical orbital implants and assess whether the coatings influence fibrovascular ingrowth. METHODS: The aluminium oxide spheres (three coated with hydroxyapatite, three coated with calcium metaphosphate and three uncoated) were manufactured at the School of Materials Engineering, Yeungnam University, Kyongsan, Kyongbuk, Korea. The implants were examined macroscopically and with scanning electron microscopy and were analysed chemically by means of x-ray powder diffraction and x-ray fluorescence spectrophotometry. Implantation of three hydroxyapatite-coated, three calcium metaphosphate-coated and three uncoated aluminium oxide spheres was done in nine adult male New Zealand albino rabbits. Implant vascularization was evaluated at 4, 8 and 12 weeks by means of histopathological sectioning. RESULTS: All three types of implant had multiple interconnected pores. The coatings increased the size of the trabeculae from 150 microm to 300 microm. As a result, the pores appeared slightly smaller but still ranged in size from 300 microm to 750 microm, compared to 400 microm to 800 microm in the uncoated implants. The coatings also increased the weight of the implants slightly. The implants were all strong mechanically. They were made up primarily of aluminium oxide. The coated implants contained significant amounts of calcium oxide (a contaminant). There was no clinical difference in the socket response between the three groups. Histopathologically, fibrovascularization occurred uniformly throughout each implant at 4, 8 and 12 weeks after implantation. INTERPRETATION: The hydroxyapatite and calcium metaphosphate coatings did not appear to facilitate or inhibit fibrovascular ingrowth at 4, 8 and 12 weeks. Longer-term studies are need to determine whether the coatings play a role in long-term acceptance and retention of the implants.

Aluminum Oxide↗
PubMed2002

An anhydrous polymorphic form of trehalose.

An anhydrous polymorphic form of alpha,alpha-trehalose was prepared from trehalose dihydrate by two different drying methods: (1) heating under vacuum; and (2) heating in hot air. Preparation of this anhydrous form by vacuum heating showed good reproducibility. This form was characterized by X-ray powder diffraction analysis and differential scanning calorimetry. This anhydrous form was converted to an amorphous phase at 127 degrees C and was found to be hygroscopic. At 43% relative humidity at 25 degrees C, this form rapidly reverted to dihydrate, while the amorphous phase remained unchanged. When an amorphous phase coexisted with this form, the rate of water adsorption to the amorphous phase was slower than that to the amorphous phase alone. These properties of this anhydrous form of alpha,alpha-trehalose may explain the effects of trehalose in dehydration tolerance of plants and insects in the desert.

Calorimetry, Differential Scanning↗
PubMed1998

Structure of the enzymatically synthesized fructan inulin.

Construction, purification and characterization of a fusion protein of maltose-binding protein of Escherichia coli and the fructosyltransferase of Streptococcus mutans is described. With the purified protein, in vitro synthesis of inulin was performed. The obtained polysaccharide was characterized by high-performance size-exclusion chromatography (HPSEC) and static light scattering (SLS) in dilute aqueous and dimethyl sulfoxide solution. For all samples very high molecular weights between 60 x 10(6) and 90 x 10(6) g/mol and a remarkable small polydispersity index of 1.1 have been determined. Small root-mean-square radii of gyration point to a compact conformation in dilute solution. No difference between native and enzymatically synthesized inulin was observed by X-ray powder diffraction and thermoanalysis of solid samples.

ATP-Binding Cassette Transporters↗