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In this paper, mesoporous alumina with different pore sizes and wall crystalline structures was synthesized at calcination temperatures over 550 degrees C. The characterization of the samples calcined at 550, 800, 1100, and 1300 degrees C, respectively, was performed using TEM, XRD, FTIR, TG/DTA, and N2 adsorption/desorption techniques. The correlation between pore size and wall crystalline structure on calcination temperature was systematically investigated.
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PMID:Effects of calcination temperature on the pore size and wall crystalline structure of mesoporous alumina. 1808 83

In this work, Fe-doped mixed crystal TiO2 powder as sonocatalyst was prepared by the sol-gel method and heat treatment, and a novel method combined with ultrasonic irradiation was propounded to degrade the organic polluted water. First, the Fe-doped mixed crystal TiO2 powder was characterized by TG-DTA, XRD, and TEM techniques. Ultrasound was used as the irradiation source and the azo fuchsine was chose as the model compound. Then a series of degradation experiments was carried out in the presence of Fe-doped mixed crystal TiO2 powder. Also, the degradation process and some influencing factors, such as irradiation time, doping Fe3+ ion content, added amount of catalyst, and initial concentration of azo fuchsine solution, on the degradation were investigated by UV-vis spectra, ion chromatography, and HPLC. Through the degradation of azo fuchsine, it was found that the combination of ultrasonic irradiation and Fe-doped mixed crystal TiO2 powder can completely degrade the azo fuchsine in aqueous solution. Because of the good degradation efficiency, this method may be an advisable choice for the treatments of non- or low-transparent wastewaters in the future.
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PMID:Preparation of Fe-doped mixed crystal TiO2 catalyst and investigation of its sonocatalytic activity during degradation of azo fuchsine under ultrasonic irradiation. 1820 58

Iron oxide thin films were prepared by spin-coating a gel solution of iron(III) nitrate dissolved in 2-methoxyethanol and acetylacetone on glass and quartz substrates. The film thickness was adjusted by changing the spinning rate of the spin coater. Annealing was carried out between 300 degrees C to 600 degrees C to investigate the phases present in the films. Viscosity of the main solution was found as 0.0035 Pa.s by viscosity measurement. TGA/DTA analyses showed that heat treatment should be done between 330 degrees C and 440 degrees C in order to produce maghemite thin films. SEM studies showed that single layer thickness of the films were between 65 and 80 nm. The structural characteristics were evaluated by changing the experimental parameters which are annealing temperature, annealing time and thickness of the films. From the X-ray diffraction analysis, maghemite formation was observed with decreasing annealing temperature, annealing time and film thickness. TEM results verified the presence of the maghemite phase by electron diffraction and selected area electron diffraction (SAED) methods. According to UV-Vis results transmittance of the films decreases with increasing annealing temperature.
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PMID:Characterization of iron oxide thin films prepared by sol-gel processing. 1846 25

In this paper, we describe a facile and rapid method for preparing In2S3 nanoparticles via ultrasound dispersion. This method allows us to prepare In2S3 nanoparticles from bulk indium and sulfur with ease and without using expensive agents and in a short time. The possible growing mechanism of the In2S3 nanoparticles was presented. In addition, we provide detailed characterizations including TEM, XRD, TG-DTA, and XPS to study the shape, composition and structure of In2S3 nanoparticles. We also studied the tribology property of In2S3 nanoparticles made using this novel recipe.
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PMID:Preparation of In2S3 nanopraricle by ultrasonic dispersion and its tribology property. 1876 41

A series of mesoporous titania materials modified with tungstophosphoric acid (TPA) were successfully synthesized by using urea as low-cost template via sol-gel reactions, followed by removing the urea by extraction with water. They were characterized by FT-IR, 31P MAS-NMR, XRD, DTA-TGA, DRS, TEM and BET. The samples presented mesopores with a diameter higher than 3.0 nm. The S(BET) of the solids decreases with the increase of the TPA content and with the increase of the calcination temperature. According to FT-IR and 31P MAS-NMR studies the main species present in the samples is [PW12O40]3- anions, which was partially transformed into [P2W21O71]6- and [PW11O39]7- anion during the synthesis and drying step. The XRD patterns of the modified samples only exhibited the characteristic peaks of anatase phase. The presence of TPA retarded the crystallization of the anatase phase and its transformation into rutile phase. The point of zero charge decreased in parallel with the increment of tungstophosphoric acid in the samples and with the increase of the calcination temperature. The band gap energy decreased as a result of the introduction of TPA into the TiO2 matrix, but remained practically constant with the increase of the calcination temperature.
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PMID:Direct modification with tungstophosphoric acid of mesoporous titania synthesized by urea-templated sol-gel reactions. 1879 Apr 94

An organic-inorganic hybrid poly-o-toluidine Th(IV) phosphate was chemically synthesized by mixing ortho-tolidine into the gel of Th(IV) phosphate in different mixing volume ratios, concentration of inorganic reactant with a fixed mixing volume ratios of organic polymer. The physico-chemical characterization was carried out by elemental analysis, TEM, SEM, XRD, FTIR and simultaneous TGA-DTA studies. The ion-exchange capacity, chemical stability, effect of eluant concentration, elution behavior and pH titration studies were also carried out to understand the ion-exchange capabilities. The distribution studies revealed that the cation-exchange material is highly selective for Hg(2+), which is an important environmental pollutant. Due to selective nature of the cation-exchanger ion-selective membrane electrode was fabricated for the determination of Hg(II) ions in solutions. The analytical utility of this electrode was established by employing it as an indicator electrode in electrometric titrations.
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PMID:Preparation and characterization of a new organic-inorganic nano-composite poly-o-toluidine Th(IV) phosphate: Its analytical applications as cation-exchanger and in making ion-selective electrode. 1907 75

In the present paper, homogenous precipitation with Nd(NO)3.6H2O and (NH)2CzO4.2H2O, a strong base anion exchange resin and strong acidic cation exchange resin, respectively, and subsequent calcination of precursors at 700 C were used to synthesize Nd2O3 nanoparticles. In the precipitation from homogeneous solution, the relative supersaturation is always low and the local reagent excesses do not occur because the precipitating agent appears homogeneously throughout the entire solution. In general, homogeneous precipitates are better suited for analysis than precipitates formed by direct addition of a reagent. The concentration of reactant, reaction temperature and time are important factors which dominate the morphology and structure size of the Nd2O3 nanoparticles. Assay results showed that between 40 and 50 degrees C, when the ion exchange resin was added tardily with continuous stirring and mixing, the precursor could be obtained after being filtered, washed, and dried at 80 degrees C. The Nd2O3 Sample was obtained via calcination of the precursor at 700 degrees C for 1.5 h. The morphology, size and distribution of the precursors and samples were characterized by TG-DTA, XRD, TEM, HR-TEM, SAED and BET techniques. The forming mechanism of homogenous precipitation was discussed detailedly. The results indicated that the Nd2O3 nanocrystal prepared with the present method belonged to hexagonal crystal system, and its average diameter was 26-32 nm with better decentralization. The electron diffraction pattern which had a clear and regular lattice of Nd2O3 confirmed that the particles were monocrystals. The specific surface area of sample a and sample b was 42. 57 and 29.43 m2 x g(-1), respectively. The ion exchange resin homogenous precipitation method has such advantages as low cost, environmentally benign innocuity of the starting reagents, the simplicity of the synthetic route, easy recycling of ion exchange resin and so on, making it a promising method to be scaled up for industrial production.
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PMID:[Preparation of Nd2O3 nanoparticles by ion exchange resin homogenous precipitation method]. 1912 19

Thermolysis of fullerene iron and ruthenium complexes (buckymetallocene M(C(60)R(5))Cp (M = Fe; R = Ph (1) and Me (2), M = Ru; R = Ph (3), Me (4)) under a nitrogen atmosphere produced metal nanoparticles dispersed in carbon materials. The thermal degradation processes of the buckymetallocenes were studied by TG-DTA, TEM with a heating sample stage, and VT-XRD. Variation of the thermolysis temperature led to a change in the size of the nanoparticles and the morphology of the carbon materials. Thermolysis of buckyferrocene at 700 degrees C gave highly dispersed iron nanoparticles (average diameter of 7.4 nm). After thermal treatment at 900 degrees C, graphite structures such as carbon nanocapsules and carbon nanotubes formed because of the catalytic activity of the iron nanoparticles. Ruthenium nanoparticles prepared from buckyruthenocene were much smaller than the iron counterparts, and did not catalyze the formation of graphite structures. When buckyruthenocene absorbed on silica gel was heated at 500 degrees C under a hydrogen atmosphere, the resulting ruthenium nanoparticles showed high activity in catalytic hydrogenation.
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PMID:Iron and ruthenium nanoparticles in carbon prepared by thermolysis of buckymetallocenes. 1913 36

Multi-walled carbon nanotubes (MWCNTs)-TiO(2) composite photocatalysts with excellent activity were prepared by sol-gel method in order to investigate its photocatalytic activity under solar irradiation for the degradation of 2,6-dinitro-p-cresol (DNPC) in aqueous solution. The prepared composite were analyzed by XRD, FTIR, SEM, TEM, TG-DTA and UV-vis absorption spectra techniques. The results showed that the composite can cause an obvious red shift of UV-vis spectra compared with pure TiO(2). The degradation of DNPC by MWCNTs-TiO(2) composite photocatalysts under solar irradiation was systematically studied by varying the experimental parameters such as pH value, irradiation time, the initial substrate concentration, reaction temperature, catalyst concentration, etc. The optimal conditions were a DNPC concentration of 33.4 mgL(-1) at pH 6.0 with MWCNTs-TiO(2) concentration of 6.0gL(-1) under solar irradiation for the illumination of 150 min. The presence of MWCNTs can enhance the photoefficiency of TiO(2). The highest efficiency on photodegradation of DNPC can be achieved with an optimal MWCNTs/TiO(2) mass ratio of 0.05%. The photocatalytic degradation of DNPC obeys a pseudo-first-order behavior according to the Langmuir-Hinshelwood model, and possible decomposing mechanisms are also discussed. The photocatalyst was used for five cycles with photocatalytic degradation efficiency still higher than 96%. The results of the study showed the feasible and potential use of MWCNTs-TiO(2) composite in degradation of toxic organic pollutants.
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PMID:Solar photocatalytic degradation of 2,6-dinitro-p-cresol (DNPC) using multi-walled carbon nanotubes (MWCNTs)-TiO(2) composite photocatalysts. 1920 48

ZnO nanostructures with different morphologies and optical properties were prepared by a simple microemulsion process, and PEG400 was used as a directing agent. The samples were characterized by TEM, XRD, FTIR, and TG-DTA analysis. The XRD spectra indicate that the ZnO crystal has a hexagonal wurtzite structure. Needle-like, columnar, and spherical ZnO samples were synthesized respectively with the increase of PEG400 concentration in Zn(NO(3))(2) solution. TEM images and thermogravimetric analysis reveal that the microemulsion interface and the PEG400 agent have a synergistic effect on the morphology and crystalline size transition of ZnO nanostructures. The optical properties of the samples were investigated by measuring the UV-Vis absorbance spectra at room temperature. All the samples exhibit strong UV absorption at around 365 nm. ZnO products with band gap energies at 3.06, 3.02, 2.95, and 2.85 eV were obtained with 0, 12.5, 25.0, and 50.0% of PEG400 in Zn(NO(3))(2) solution, respectively. The formation mechanism of the ZnO nanostructures was proposed and discussed in detail. The synergistic control of the microemulsion interface and the agent on the growth of crystal nuclei reported here provides an alternative approach for preparation of other well-defined nanostructures.
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PMID:Synthesis and morphology control of ZnO nanostructures in microemulsions. 1928 90


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