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Four kinds of manganese oxides with either layered or tunnel structures were prepared by different methods. The structural features of the prepared materials were characterized by power X-ray diffraction, IR spectra and SEM observation. A compare analysis of IR spectra for these materials before and after the acid treatment was carried out. Band around 761 cm(-1) could be assigned to a characteristic adsorbent band of tunnel-type manganese oxides; while it was not observed in layer-type manganese oxides. After the acid treatment, the position and relative intensity of the bands in 300-1200 cm(-1) region showed an obvious change for layered manganese oxides in compare with tunnel-type manganese oxides. The variation of IR spectra could be used to distinguish layered manganese oxides from tunnel manganese oxides.
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PMID:IR spectra of manganese oxides with either layered or tunnel structures. 1704 37

The mesoporous MnSBA-15 materials with different n(Si)/n(Mn) ratios of 4, 8, 20, and 50 have been synthesized, for the first time, using manganese nitrate tetrahydrate and Pluronic 123 triblock polymer [(EO)20(PO)70(EO)20] by simply adjusting the molar ratio of water to hydrochloric acid (n(H2O)/n(HCl)) under direct hydrothermal conditions. For the effect of structural and textural properties with incorporation of manganese, the MnSBA-15 has been synthesized with different synthesis temperatures at the fixed molar ratios of n(Si)/n(Mn) = 4 and n(H2O)/n(HCl) = 295 in the synthesis gel. The hydrothermal and thermal stabilities of MnSBA-15 have also been investigated. The calcined MnSBA-15 materials prepared have been characterized by ICP-AES, XRD, N2 adsorption, ESR, FE-SEM, and TEM. The ICP-AES studies show a higher amount of manganese incorporation on the silica pore walls, as MnSBA-15 with a n(Si)/n(Mn) ratio up to 2.2 can be successfully prepared at a fixed n(H2O)/n(HCl) molar ratio of 295 by adjusting the ratios of n(Si)/n(Mn) in the synthesis gel. The structural and textural properties of calcined MnSBA-15 prepared can be found by the results of XRD and N2 adsorption. The investigation of ESR results clearly describe the effect of structure and Mn species coordination on the SBA-15 silica pore walls while the uniform pore diameter and rope-like hexagonal mesoporous structure of MnSBA-15 can be identified by TEM and FE-SEM images. With increasing synthesis temperature, an increase the unit cell parameter, pore size, and pore volume and a decrease the specific surface area and pore wall thickness of MnSBA-15 can be obviously noted by the results of XRD and N2 adsorption. The hexagonal MnSBA-15 materials prepared could be tested as catalysts in epoxidation of trans-stilbene to produce trans-stilbene oxide under various optimal conditions while their catalytic properties could also be compared to the results of MnMCM-41 and ZrMnMCM-41.
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PMID:Direct synthesis of well-ordered and unusually reactive MnSBA-15 mesoporous molecular sieves with high manganese content. 1706 42

SiO(2)-TiO(2) pillared layered manganese oxide nanohybrid was successfully synthesized by preliminarily expanding the interlayer of H-type layered manganese oxide using dodecylamine, followed by reacting it with a mixture solution of titanium isopropoxide and tetraethylorthosilicate. The basal spacing and the pillared agent content of the obtained materials connected with the length of intercalated n-alkylamine, incorporated Si/Ti molar ratios and the solvothermal treatment temperature. The structural evolution of SiO(2)-TiO(2) pillared layered manganese oxide nanohybrid was characterized by XRD, DSC-TGA, SEM, IR, N(2) adsorption-desorption and element analyses. TiO(2) particles exhibited a stronger affinity for the negatively charged manganese layers, and the TiO(2) particles incorporated were independently intercalated without any distinct chemical bonding with the co-intercalated SiO(2) particles. SiO(2)-TiO(2) pillared layered manganese oxide nanohybrid had a BET surface area of 98 m(2)/g with a gallery height of about 1.43 nm between layers. The obtained SiO(2)-TiO(2) co-pillared layered manganese oxide nanohybrid is expected as a selective catalyst, or an improved battery material.
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PMID:Preparation and structural evolution of SiO(2)-TiO(2) pillared layered manganese oxide nanocomposite upon intercalating reaction. 1718 3

Arsenite (As(III)) is more toxic and more difficult to remove from water than arsenate (As(V)). As there is no simple treatment for the efficient removal of As(III), an oxidation step is always necessary to achieve higher removal. However, this leads to a complicated operation and is not cost-effective. To overcome these disadvantage, a novel Fe-Mn binary oxide material which combined the oxidation property of manganese dioxide and the high adsorption features to As(V) of iron oxides, were developed from low cost materials using a simultaneous oxidation and coprecipitation method. The adsorbent was characterized by BET surface areas measurement, powder XRD, SEM, and XPS. The results showed that prepared Fe-Mn binary oxide with a high surface area (265 m2 g(-1)) was amorphous. Iron and manganese existed mainly in the oxidation state +III and IV, respectively. Laboratory experiments were carried out to investigate adsorption kinetics, adsorption capacity of the adsorbent and the effect of solution pH values on arsenic removal. Batch experimental results showed that the adsorbent could completely oxidize As(III) to As(V) and was effective for both As(V) and As(III) removal, particularly the As(III). The maximal adsorption capacities of As(V) and As(III) were 0.93 mmol g(-1) and 1.77 mmol g(-1), respectively. The results compare favorably with those obtained using other adsorbent. The effects of anions such as SO4(2-), PO4(3-), SiO3(2-), CO3(2-) and humic acid (HA), which possibly exist in natural water, on As(III) removal were also investigated. The results indicated that phosphate was the greatest competitor with arsenic for adsorptive sites on the adsorbent. The presence of sulfate and HA had no significant effect on arsenic removal. The high uptake capability of the Fe-Mn binary oxide makes it potentially attractive adsorbent for the removal of As(III) from aqueous solution.
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PMID:Preparation and evaluation of a novel Fe-Mn binary oxide adsorbent for effective arsenite removal. 1738 91

It has recently been shown that the antianginal drug bepridil (BEP) activates mitochondrial ATP-sensitive potassium (mitoK(ATP)) channels and thus confers cardioprotection. Our aim was to investigate whether BEP could induce preconditioning in cultured rat cortical neurons. Although BEP depolarized isolated and in situ mitochondria and increased reactive oxygen species generation, no acute protection was observed. However, a 3-day BEP-treatment elicited dose-dependent delayed neuroprotection against 180 min of oxygen-glucose deprivation (cell viability: untreated, 52.5 +/- 0.85%; BEP 1 micromol/L, 59.6 +/- 1.53%*; BEP 2.5 micromol/L, 71.9 +/- 1.23%*; BEP 5 micromol/L, 95.3 +/- 0.89%*; mean +/- SEM; *p < 0.05 vs. untreated) and 60 min of glutamate excitotoxicity (200 micromol/L; cell viability: untreated, 54.1 +/- 0.69%; BEP 1 micromol/L, 61.2 +/- 1.19%*; BEP 2.5 micromol/L, 78.1 +/- 1.67%*; BEP 5 micromol/L, 91.2 +/- 1.20%*; mean +/- SEM; *p < 0.05 vs. untreated), and inhibited the reactive oxygen species surge upon glutamate exposure. The protection was antagonized with co-application of the superoxide dismutase mimetic M40401, but not with reduced glutathione, catalase, or with the mitoK(ATP) blocker 5-hydroxydecanoate. Furthermore, BEP treatment resulted in increased levels of phosphorylated protein kinase C, manganese-dependent superoxide dismutase, glutathione peroxidase, and Bcl-2. Our results indicate that BEP induces delayed neuronal preconditioning which is dependent on superoxide generation but perhaps not on direct mitoK(ATP) activation.
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PMID:Neuronal preconditioning with the antianginal drug, bepridil. 1739 52

The corrosion resistance of AISI 304 stainless steel (AISI 304 SS) and manganese stainless steel (low-nickel SS) brackets in artificial saliva was investigated. The cytotoxic effects of their corrosion products on L929 cell culture were compared by two assays, crystal violet, to evaluate cell viability, and MTT (3-[4,5-dimethylthiazol-2-yl]2,5-diphenyltetrazolium bromide), for cell metabolism and proliferation. The atomic absorption spectroscopic analysis of the corrosion products demonstrated that nickel and manganese ion concentrations were higher for the AISI 304 SS-bracket immersion solution as compared with the low-nickel SS brackets. Scanning electron microscopy and energy-dispersive spectroscopy demonstrated less corrosion resistance for the AISI 304 SS brackets. Although none of the bracket extracts altered L929 cell viability or morphology, the AISI 304 SS-bracket extracts decreased cellular metabolism slightly. The results indicated that the low-nickel SS presents better in vitro biocompatibility than AISI 304 SS brackets. Abbreviations used: AISI, American Iron and Steel Institute; EDS, energy-dispersive spectroscopy; OD, optical density; ISO, International Organization for Standardization; MTT, (3-{4,5 dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; NiSO(4), nickel sulfate; SEM, standard error of the mean; WHO, World Health Organization; and TNF, tumor necrosis factor.
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PMID:In vitro evaluation of corrosion and cytotoxicity of orthodontic brackets. 1745 65

One-dimensional Mn(2+)-doped CdS nanocrystals were synthesized by the hydrothermal route. The products were characterized by SEM, EDS, XRD, TEM, HRTEM and PL, respectively. The results revealed that dopant Mn2+ completely substitutes Cd2+ in CdS nanocrystals, and the product was of good crystallite. Further more, a complete suppression of the emission from surface states at room temperature when doping with ions Mn2+ has been observed.
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PMID:[Hydrothermal synthesis and luminescence of one-dimensional Mn(2+)-doped CdS nanocrystals]. 1776 56

Hyperaccumulation by plants is a rare phenomenon that has potential practical benefits. The majority of manganese (Mn) hyperaccumulators discovered to date occur in New Caledonia, and little is known about their ecophysiology. This study reports on natural populations of one such species, the endemic shrub Maytenus founieri. Mean foliar Mn concentrations of two populations growing on ultramafic substrates with varying soil pHs were obtained. Leaf anatomies were examined by light microscopy, while the spatial distributions of foliar Mn in both populations were examined by qualitative scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS). Plants growing on two different substrates were found to have very different mean dry weight (DW) foliar Mn concentrations. Light microscopy showed that the leaves had very distinct thick dermal structures, consisting of multiple layers of large cells in the hypodermis. In vivo X-ray microprobe analyses revealed that, in both populations, Mn sequestration occurred primarily in these dermal tissues. The finding here that foliar Mn is most highly localized in the nonphotosynthetic tissues of M. founieri contrasts with results from similar studies on other woody species that accumulate high Mn concentrations in their shoots.
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PMID:Foliar manganese accumulation by Maytenus founieri (Celastraceae) in its native New Caledonian habitats: populational variation and localization by X-ray microanalysis. 1798 81

Depleted fullerene soot (DFS) with fullerene residue content of about 2.2-3.2% are investigated in order to elucidate the possibility for their use as support of catalysts in low-temperature reduction of NO with CO. Bimetalic copper-cobalt and copper-manganese oxides supported on DFS are prepared. All samples are characterized by chemical analysis, XRD, SEM, IR spectroscopy, XPS, nitrogen adsorption measurements. The two DFS supported bimetallic catalysts manifest a high activity towards the reduction of NO with CO at temperatures below 150 degrees C, the CuCo/DFS being the more active one. The peculiarity of the support DFS predetermines the porous texture of the catalysts. The occurrence of a specific metal-support interaction favors the formation of the mixed oxide spinels CuCo2O4 and Cu1.5 Mn1.5 O4 that are responsible for the enhanced activity.
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PMID:Novel application of depleted fullerene soot (DFS) as support of catalysts for low-temperature reduction of NO with CO. 1819 47

Metal complexes of o-vanillidene-2-aminobenzothiazole have been prepared and characterized by elemental and spectral (vibrational, electronic, 1H NMR and EPR) data as well as magnetic susceptibility measurements and thermo gravimetric analysis (TG/DTA). The low molar conductance values reveal the non-electrolytic nature of these complexes. The elemental analysis suggests that the stoichiometry to be 1:2 (metal:ligand). Magnetic susceptibility data coupled with electronic spectra suggest that two ligands coordinate to each metal atom by phenolic oxygen and imino nitrogen to form high spin octahedral complex with Co(II), Mn(II) and Ni(II). The fifth and sixth position of metal ion is satisfied with water molecules. The thermal behaviour (TG/DTA) of the synthesised complexes shows that the complexes loss water molecules in the first step followed by decomposition of the ligand. Spin Hamiltonian parameters predict a distorted tetrahedral geometry for the copper complex. XRD and SEM analysis provide the crystalline nature and the morphology of the metal complexes. The in vitro biological activity of the metal chelates is tested against the Gram positive bacteria (Bacillus amyloliquifacians) and gram negative bacteria (Pseudomonas species), fungus (Aspergillus niger) and yeast (Sacchromyces cereviaceae). Most of the metal chelates exhibited higher biological activities.
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PMID:Spectral, XRD, SEM and biological activities of transition metal complexes of polydentate ligands containing thiazole moiety. 1831 76


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