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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ba(dmae)2 (dmaeH=N,N-dimethylaminoethanol, C4H11NO) reacts with Co(acac)2 (acac=2,4-pentanedionate) to produce the trinuclear coordination complex [Ba2Co(acac)4(dmae)3(dmaeH)] in an 85% yield. Spectroscopic and single-crystal X-ray diffraction experiments indicate that the complex possesses a structure in which two barium atoms and a cobalt atom are bridged by acac and dmae groups. The barium centers are eight and nine coordinate with BaO7N and BaO7N2 coordination spheres while the cobalt is a more regular CoO5N octahedron. This 2:1 heterobimetallic molecular complex was investigated as precursor for the deposition of thin film by AACVD. The film was characterized by SEM and XRD. TGA shows that the complex starts thermal decomposition upon heating in nitrogen atmosphere at 105 degrees C to produce barium cobalt oxide material of a Ba2CoO3 composition with an orthorhombic structure. The synthetic approach detailed here represents a unique route to the formation of a heterobimetallic barium cobalt coordination complex.
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PMID:Synthesis and structural characterization of a new heterobimetallic coordination complex of barium and cobalt for use as a precursor for chemical vapor deposition. 1632 1

An organic-inorganic hybrid material, TPPhA-Ti, was constructed by non-hydrolytic condensation of a dendritic tetrakis-1,3,5,7-(4-phosphonatophenyl)adamantane precursor and titanium(IV) isopropoxide. One preparative pathway yielded insoluble materials with a Ti/P ratio of approximately 1 which was confirmed by a combination of FT-IR, TGA, and EDS measurements. N2 sorption experiments showed that TPPhA-Ti is a porous solid (micropores approximately 13 A; mesopores approximately 38 A) with a high surface area, approximately 550 m2 g(-1). The structure and morphology of the TPPhA-Ti as investigated by transmission and scanning electron microscopy showed a layered-type material. Additional X-ray diffraction data suggest a paracrystalline material; an optimization of possible molecular arrangements of TPPhA-Ti was simulated that was in agreement with the experimental data. A second preparative pathway yielded a Ti oxide-phosphonate with a Ti/P ratio of approximately 3.4. Both TEM and SEM revealed that hollow nanospheres were formed with diameters of approximately 180-300 nm.
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PMID:Titanium phosphonate porous materials constructed from dendritic tetraphosphonates. 1649 93

A new titanium(IV) oxide-hectorite nanofilm photocatalyst was prepared on quartz slides. It was evaluated in the photooxidation of dibenzothiophene (DBT) in nonpolar organic solution (tetradecane), as a model for diesel fuel. A removal regimen was developed consisting of catalytic photooxidation followed by adsorption of products on silica gel. Photooxidation of DBT was performed with and without catalyst, at 254 and 300 nm. Comparison was made with a commercially available TiO(2) catalyst, Degussa P25. The catalyst was analyzed by nitrogen adsorption, XRD, SEM, and TGA-DTA. DBT concentrations were measured by HPLC and UV spectrophotometry. Preliminary qualititative analysis of products was performed by UV and HPLC. Results indicated that the outlined process was effective in reducing sulfur levels to below 10 ppm sulfur.
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PMID:Photooxidation of dibenzothiophene on TiO(2)/hectorite thin films layered catalyst. 1660 Feb 76

An iron hydroxide floc is used as treatment for adsorbing low amounts of actinides during nuclear fuel re-processing. This waste is cemented only after pre-treatment with Ca(OH)(2). Characterisation of all simulant material has been undertaken using XRD, TGA and SEM/EDS. The floc is a moderately alkaline colloidal slurry containing approximately 15wt% solids, with the main particulate being an amorphous hydrated iron oxide. The main phase formed during pre-treatment appears to be an X-ray amorphous hydrated calcium-ferrate phase. Embedded within this are small amounts of crystalline Ca(OH)(2), calcite, Fe(6)(OH)(12)(CO(3)), Ca(6)Fe(2)(SO(4))(3)(OH)(12).26H(2)O and Ca(3)B(2)O(6), and can form depending on concentrations of Ca(OH)(2) and time. Apart from Ca(OH)(2) and calcite, none of the crystalline phases detected during pre-treatment are detected when the floc is encapsulated in an OPC/PFA composite cement hydrated for 90 days. The main crystalline phase detected in the hardened wasteform is a solid solution hydrogarnet, Ca(3)AlFe(SiO(4))(OH)(8), known as C(3)(A,F)SH(4) in cement chemistry nomenclature.
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PMID:The disposal of radioactive ferric floc. 1662 43

This article reports on the synthesis of high surface area (563m2/g) beta-SiC nanorods by thermal decomposition of commercial silicone oil at a relatively low reaction temperature (800 degrees C) in a closed Swagelok cell. High yield (75%) of SiC nanorods are obtained in this one-stage, solvent-, catalyst-, and template-free synthesis technique that runs at a relative low temperature and employs cheap single-precursor. The morphological (TEM, HR-SEM), compositional (CHNS, EDX, SAEDX]), structural (XRD, HR-TEM, and ED), thermal (TGA) characterizations and surface area analysis are carried out for the obtained SiC nanorods. The possibility of hydrogen storage in this high surface area nano-SiC rods are also tested and reported for the first time.
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PMID:Thermal decomposition of commercial silicone oil to produce high yield high surface area SiC nanorods. 1677 90

Uniform radiopaque polystyrene microspheres of approximately 2.3 +/- 0.2 microm were prepared by a single-step swelling of 2.3 +/- 0.2 microm polystyrene template microspheres, dispersed in an aqueous solution with methylene chloride emulsion droplets containing 2,3,5-triiodobenzoylethyl ester. After completing the swelling process, the methylene chloride was evaporated in order to lock the 2,3,5-triiodobenzoylethyl ester in the polystyrene microspheres. The influence of the weight ratio [2,3,5-triiodobenzoylethyl ester]/[polystyrene] on the % of entrapped 2,3,5-triiodobenzoylethyl ester was elucidated. Characterization of the radiopaque polystyrene microspheres was accomplished by light microscope, FTIR, TGA, SEM, XPS, and elemental analysis. The radiopacity of the microspheres was demonstrated by an imaging technique based on X-ray absorption usually used in hospitals. This novel method of encapsulation of 2,3,5-triiodobenzoylethyl ester within polystyrene microspheres by a single-step swelling process may be used as a model for encapsulation of various hydrophobic radiopaque drugs within uniform polystyrene template particles of various diameters for different X-ray imaging needs, e.g., blood pool, body organs, embolization, dental composition, implants, protheses, and nanocomposites.
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PMID:Synthesis and characterization of uniform radiopaque polystyrene microspheres for X-ray imaging by a single-step swelling process. 1678 70

Nanoscale metal-organic frameworks (NMOFs) based on Gd3+ centers and benzenedicarboxylate and benzenetricarboxylate bridging ligands were synthesized using reverse microemulsions and characterized using SEM, PXRD, and TGA. These NMOFs exhibit extraordinarily large R1 and R2 relaxivities because of the presence of up to tens of millions of Gd3+ centers in each nanoparticle and are thus efficient T1 and T2 contrast agents for MRI. The NMOFs can also be made highly luminescent by doping with Eu3+ or Tb3+ centers. The results from this work suggest that NMOFs can be used as potential contrast agents for multimodal imaging.
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PMID:Nanoscale metal-organic frameworks as potential multimodal contrast enhancing agents. 1683 62

Poly(vinylidenefluoride)-hexafluoropropylene (PVdF(HFP))-ionic liquid gel electrolytes were prepared using ionic liquids based on 1-(2-hydroxyethyl)-3-methyl imidazolium tetrafluoroborate and 1-(2-hydroxyethyl)-3-methyl imidazolium hexafluorophosphate. A conventional metathesis reaction was used to prepare these ionic liquids, which have high purity and exhibit a liquid state at room temperature. The prepared polymer-ionic liquid gel proved to be a free-standing and rubbery film in which the degree of transparency differed according to the ratio and type of ionic liquid used. TGA and FTIR analyses confirmed that the solvent, N,N-Dimethylacetamide (DMAC), used for mixing PVdF(HFP) polymer with ionic liquid was almost totally removed during the gelling and drying processes. SEM photographs were taken of the surface structure of the PVdF(HFP)-ionic liquid gel in order to evaluate the morphology of the film's surface according to the mixing ratio and the nature of the ionic liquid. The thermal behaviors of PVdF(HFP)-ionic liquid gels were observed to be similar to those of neat ionic liquids through DSC analysis, and the compatibility between the polymer and ionic liquid was investigated by XRD analysis. The ionic conductivities of all the gels were 10(-3)-10(-5) S cm(-1) in a temperature range of 20-70 degrees C.
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PMID:Characterization of PVdF(HFP) gel electrolytes based on 1-(2-Hydroxyethyl)-3-methyl imidazolium ionic liquids. 1685 1

Nanoscaled TiO2 powders with narrow size dispersion were prepared in supercritical carbon dioxide via non-hydrolytic acylation/deacylation of titanium alkoxide precursors with or without tris-fluorination. The microstructures of these powders were characterized by spectroscopic (FTIR, TGA, and XRD), microscopic (SEM or TEM), and surface area (BET) measurements. Photocatalytic oxidation of 1-octanol on these calcined TiO2 powders and on commercial T805 TiO2 suspended in aerated supercritical carbon dioxide revealed relative reactivity controlled by the powder microstructures. Calcined TiO2 prepared from titanium(IV) isopropoxide and trifluoroacetic anhydride was effectively dispersed in aerated supercritical carbon dioxide under stirring and exhibited high photocatalytic oxidation activity.
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PMID:Synthesis of TiO2 photocatalysts in supercritical CO2 via a non-hydrolytic route. 1685 17

We report a simple and efficient single-step synthesis of tungsten carbide nanorods and nanoplatelets by direct pyrolysis of a hybrid composite material of 12-tungstophosphoric acid and hexadecyltrimethylammonium bromide in a closed Swagelok cell at 1000 degrees C. The product was characterized by XRD, TGA, SEM, TEM, XPS, and CV. The diameter of the nanorods is 30-50 nm, and the length varies from 200 to 500 nm. The size of the platelets is around 55 nm. The WC exhibits an interesting structural surface with kinks, steps, and terraces which is evidenced by HRTEM studies.
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PMID:Solid state synthesis of tungsten carbide nanorods and nanoplatelets by a single-step pyrolysis. 1685 56


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