998 resultados para Hidrotérmico synthesis


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A decentralized emission inventories are prepared for road transport sector of India in order to design and implement suitable technologies and policies for appropriate mitigation measures. Globalization and liberalization policies of the government in 90's have increased the number of road vehicles nearly 92.6% from 1980-1981 to 2003-2004. These vehicles mainly consume non-renewable fossil fuels, and are a major contributor of green house gases, particularly CO2 emission. This paper focuses on the statewise road transport emissions (CO2, CH4, CO, N-x, N2O, SO2, PM and HC) using region specific mass emission factors for each type of vehicles. The country level emissions (CO2, CH4, CO, NOx, N2O, SO2 and NMVOC) are calculated for railways, shipping and airway, based on fuel types. In India, transport sector emits an estimated 258.10 Tg Of CO2, of which 94.5% was contributed by road transport (2003-2004). Among all the states and Union Territories, Maharashtra's contribution is the largest, 28.85 Tg (11.8%) Of CO2, followed by Tamil Nadu 26.41 Tg(10.8%), Gujarat 23.31 Tg(9.6%), Uttar Pradesh 17.42 Tg(7.1%), Rajasthan 15.17 Tg (6.22%) and, Karnataka 15.09 Tg (6.19%). These six states account for 51.8% of the CO2 emissions from road transport.

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Nanoparticles of Fe3O4 were synthesized by co-precipitation in an aqueous solution containing ferrous and ferric salts (1:2) at varying pH with ammonia as a base. It was found that the value of pH influences the reaction mechanism for the formation of Fe3O4. Furthermore, the addition of mercaptoethanol significantly reduced the crystalline size of Fe3O4 nanoparticles from 15.03 to 8.02 nm. X-ray diffraction (XRD) spectra revealed that the synthesized nanoparticles were epsilon-Fe2O3 or Fe3O4 phase. To further prove the composition of the product, as-prepared Fe3O4 were examined by X-rayphotoelectron spectroscopy (XPS). Magnetic properties of the obtained particles were determined by vibrating sample magnetometer (VSM). Further analysis of the X-ray studies shows that while maintaining a pH value of 6 and 9 in a solution containing iron salts II and III ions produces epsilon-Fe2O3. Whereas a pH value of 11 produces magnetite (Fe3O4) phase. All of these results show that the pH has a major role in the observed phase formation of (Fe3O4) nanoparticles.

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Purified rinderpest virus was earlier shown to transcribe in vitro, all virus-specific mRNAs with the promoter-proximal N mRNA being the most abundant. Presently, this transcription system has been shown to synthesize full length monocistronic mRNAs comparable to those made in infected cells. Small quantities of bi- and tricistronic mRNAs are also synthesized. Rinderpest virus synthesizes in vitro, a leader RNA of not, vert, similar 55 nucleotides in length. Purified rinderpest virus also exhibits RNA editing activity during the synthesis of P mRNA as shown by primer extension analysis of the mRNA products.

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The luteotropic action of estrogen (E) was investigated using immature pseudopregnant rat as the model and CGS 16949A (Fadrozole hydrochloride), a potent aromatase inhibitor (AI), to block E synthesis. Aromatase activity could be inhibited by administering CGS 16949A (50 mu g/day/rat) via a mini osmotic Alzet pump (model 2002) for 3 days during pseudopregnancy. This resulted in significant reduction of serum (40%, P < 0.05) and intraovarian (70.6%, P < 0.001) estradiol-17 beta (E(2)) levels. The serum and intraovarian progesterone (P-4) levels as analyzed on day 4 of pseudopregnancy were also reduced by greater than or equal to 50% (for both, P < 0.01). Simultaneous administration of estradiol-3-benzoate (E(2)B) via an Alzet pump during the Al: treatment period at a dose of 1 mu g/day could completely reverse the Al induced reduction in P-4 secretion. The luteal cells of experimental rats depleted of E in vivo showed a significantly reduced response upon incubation with hCG or dbcAMP in vitro (P < 0.05 and 0.001, respectively). Addition of E(2) (500 pg/tube) at the time of in vitro incubation was able to partially increase the responsiveness to hCG. The luteal cell LH/hCG receptor content and the affinity of hCG binding to the receptor remained unchanged following AI treatment in vivo. Both esterified and total cholesterol content of luteal cells of rats treated with Al in vivo was significantly high (P < 0.05) suggesting that E lack results in an impairment in cholesterol utilization for steroidogenesis. The results clearly show that E regulates luteal function in the pseudopregnant rat by acting at a non-cAMP mediated event and this perhaps involves facilitation of cholesterol utilization at the mitochondrial level for P-4 synthesis.

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Various carbon nanostructures (CNs) have been prepared by a simple deposition technique based on the pyrolysis of a new carbon source material tetrahydrofuran (THF) mixed with ferrocene using quartz tube reactor in the temperature range 700-1100 degrees C. A detailed study of how the synthesis parameter such as growth temperature affects the morphology of the carbon nanostructures is presented. The obtained CNs are investigated by scanning electron microscope (SEM), X-ray diffraction (XRD), electron dispersive scattering (EDS)thermogravimetry analysis (TGA), Raman and transmission electron microscope (TEM). It is observed that at 700 degrees C. normal CNTs are formed. Iron filled multi-walled carbon nanotubes (MWCNTs) and carbon nanoribbons (CNRs) are formed at 950 degrees C. Magnetic characterization of iron filled MWCNTs and CNRs studied at 300 K by superconducting quantum interference device (SQUID) reveals that these nanostructures have an enhanced coercivity (Hc = 1049 Oe) higher than that of bulk Fe. The large shape anisotropy of MWCNTs, which act on the encapsulated material (Fe), is attributed for the contribution of the higher coercivity. Coiled carbon nanotubes (CCNTs) were obtained as main products in large quantities at temperature 1100 degrees C.

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A structure-based approach has been adopted to develop 2'substituted analogs of triclosan. The Cl at position 2' in ring B of triclosan was chemically substituted with other functional groups like NH2, NO2 and their inhibitory potencies against PfENR were determined. The binding energies of the 2' substituted analogs of triclosan for enoyl-acyl carrier protein reductase (ENR) of Plasmodium falciparum were determined using Autodock. Based on the autodock results, we synthesized the potential compounds. The IC50 and inhibition constant (K-i) of 2' substituted analogs of triclosan were determined against purified PfENR. Among them, two compounds,2-(2'-Amino-4'-chloro-phenoxy)-5-chloro-phenol (compound 4) and 5-chloro-2-(4'-chloro-2'-nitro-phenoxy)-phenol) (compound 5) exhibited good potencies. Compound 4 followed uncompetitive inhibition kinetics with crotonoyl CoA and competitive with NADH. It was shown to have an IC50 of 110 nM; inhibition constant was 104 nM with the substrate and 61 nM with the cofactor. IC50 Of compound 5 was determined to be 229 nM. Compounds 4 and 5 showed significant inhibition of the parasite growth in P. falciparum culture. (C) 2009 IUBMB IUBMB Life, 61(11):1083-1091, 2009.

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Two new neutral copper-azido polymers [Cu-3(N-3)(6)(tmen)(2)](n)(1)and [Cu-6(N-3)(12)(deen)(2)](n) (2) [tmen = N,N,N, N-tetramethylethylenediamine and deen = N,N-diethylethylenediamine] have been synthesized by using lower molar equivalents of the chelating diamine ligands with Cu(NO3)(2)center dot 3H(2)O and an excess of NaN3. The single crystal X-ray structure shows that in the basic unit of the 1D complex 1, the three Cu-II ions are linked by double end-on azido bridges with Cu-N-EO-Cu angles on both sides of the magnetic exchange critical angle of 108 degrees. Complex 2 is a 3D framework of a basic u-6 cluster. Cryomagnetic susceptibility measurements over a wide range of temperature exhibit dominant ferromagnetic behavior in both the complexes. Density functional theory calculations (B3LYP functional) have been performed on the trinuclear unit to provide a qualitative theoretical interpretation of the overall ferromagnetic behavior shown by the complex 1.

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Solvothermal treatment of an equimolar mixture of Co(NO3)(2)center dot 6H(2)O, HCONH2 and NaN3 in MeOH at 100 degrees C yielded a three-dimensional NaCl type network Co(HCOO)(2)(HCONH2)(2) center dot HCONH2 (1a) containing formamides in the pores of the structure. Solvated pink 1a undergoes single crystal-to-single crystal (SCSC) transformation at 215 degrees C to form the desolvated dark brown product Co(HCOO)(2)-( HCONH2)(2) (1b) with the retention of the original framework. Reversible single crystal-to-single crystal transformation of 1b (brown) to 1a (pink) in the presence of excess formamide was also established at room temperature. The coordination environment around Co(II) in both 1a and 1b is octahedral with a CoN2O4 coordination composition. A similar reaction replacing Co(II) by Cr(III) produced a heterometallic 3D extended network Na[Cr(HCOO)(4)(HCONH2)(2)]center dot 2H(2)O (2a) at 100 degrees C. An increase in reaction temperature to 150 degrees C produced a simple mononuclear complex Cr(HCOO)(3)(HCONH2)(3) center dot 3H(2)O (2b). Variable temperature magnetic studies revealed the presence of a canting phenomena in both 1a and 1b, and hysteresis loop in the field dependent magnetisation plot at 2 K whereas complex 2a is simply paramagnetic in nature.

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Metal nanoparticle photocatalysts have attracted recent interest due to their strong absorption of visible and ultraviolet light. The energy absorbed by the metal conduction electrons and the intense electric fields in close proximity, created by the localized surface plasmon resonance effect, makes the crucial contribution of activating the molecules on the metal nanoparticles which facilitates chemical transformation. There are now many examples of successful reactions catalyzed by supported nanoparticles of pure metals and of metal alloys driven by light at ambient or moderate temperatures. These examples demonstrate these materials are a novel group of efficient photocatalysts for converting solar energy to chemical energy and that the mechanisms are distinct from those of semiconductor photocatalysts. We present here an overview of recent research on direct photocatalysis of supported metal nanoparticles for organic synthesis under light irradiation and discuss the significant reaction mechanisms that occur through light irradiation.

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Two new copper(II) complexes, [Cu-2(L-1)(2)](ClO4)(2) (1) and [Cu(L-2)(ClO4)] (2), of the highly unsymmetrical tetradentate (N3O) Schiff base ligands HL1 and HL2 (where HL1 = N-(2-hydroxyacetophenone)-bis-3-aminopropylamine and HL2 = N-(salicyldehydine)-bis-3-aminopropylamine) have been synthesised using a template method. Their single crystal X-ray structures show that in complex 1 two independent copper(II) centers are doubly bridged through sphenoxo-O atoms (O1A and O1B) of the two ligands and each copper atom is five-coordinated with a distorted square pyramidal geometry. The asymmetric unit of complex 2 consists of two crystallographically independe N-(salicylidene) bis(aminopropyl)amine-copper(II) molecules, A and B, with similar square pyramidal geometries. Cryomagnetic susceptibility measurements (5-300 K) on complex 1 reveal a distinct antiferromagnetic interaction with J=-23.6 cm(-1), which is substantiated by a DFT calculation (J=-27.6 cm(-1)) using the B3LYP functional. Complex 1, immobilized over highly ordered hexagonal mesoporous silica, shows moderate catalytic activity for the epoxidation of cyclohexene and styrene in the presence of TBHP as an oxidant.

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A new and simple route for the synthesis of thioesters starting from carboxylic acids and alcohols is reported by using tetrathiomolybdate as the key sulfur transfer reagent. Triphenylphosphane and N-bromosuccinimide were used for the activation of the carboxylic acid and alcohol in the same pot followed by the transfer of sulfur from tetrathiomolybdate. Thioesters were obtained in good to moderate yields. Primary alcohols show excellent reactivity and gave good yields of the corresponding thioesters, whereas secondary alcohols gave moderate yields and tertiary alcohols were very less reactive and gave poor yields of the corresponding thioesters.

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Sr2SbMnO6 (SSM) powders were successfully synthesized at reasonably low temperatures via molten-salt synthesis (MSS) method using eutectic composition of 0.635 Li2SO4-0.365 Na2SO4 (flux). High-temperature cubic phase SSM was stabilized at room temperature by calcining the as-synthesized powders at 900 degrees C/10 h. The phase formation and morphology of these powders were characterized via X-ray powder diffraction and scanning electron microscopy, respectively. The SSM phase formation associated with similar to 60 nm sized crystallites was also confirmed by transmission electron microscopy. The activation energy associated with the particle growth was found to be 95 +/- 5 kJ mol(-1). The dielectric constant of the tetragonal phase of the ceramic (fabricated using this cubic phase powder) with and without the flux (sulphates) has been monitored as a function of frequency (100 Hz-1 MHz) at room temperature. Internal barrier layer capacitance (IBLC) model was invoked to rationalize the dielectric properties.

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Eight new open-framework inorganic-organic hybrid compounds based on indium have been synthesized employing hydrothermal methods. All of the compounds have InO6, C2O4, and HPO3/HPO4/SO4 units connected to form structures of different dimensionality Thus, the compounds have zero- (I), two- (II, III, IV, V, VII, and VIII), and three-dimensionally (VI) extended networks. The formation of the first zero-dimensional hybrid compound is noteworthy In addition, concomitant polymorphic structures have been observed in the present study. The molecular compound, I, was found to be reactive, and the transformation studies in the presence of a base (pyridine) give rise to the polymorphic structures of II and III, while the addition of an acid (H3PO3) gives rise to a new indium phosphite with a pillared layer structure (T1). Preliminary density functional theory calculations suggest that the stabilities of the polymorphs are different, with one of the forms (II) being preferred over the other, which is consistent with the observed experimental behavior. The oxalate units perform more than one role in the present structures. Thus, the oxalate units connect two In centers to satisfy the coordination requirements as well as to achieve charge balance in compounds II, IV, and VI. The terminal oxalate units observed in compounds I, IV, and V suggest the possibility of intermediate structures. Both in-plane and out-of-plane connectivity of the oxalate units were observed in compound VI. The 31 compounds have been characterized by powder X-ray diffraction, IR spectroscopy, thermogravimetric analysis, and P-31 NMR studies.

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Oxyglycals, derived from lactose and maltose, were expanded to trisaccharides through a ring expansion method. Trisaccharides with 6-7-5 and 6-7-6 ring sizes were prepared through the ring expansion method, with high diastereoselectivities, in each step of their synthesis. The NOE and ROESY NMR spectroscopies were used to assess the dipolar Couplings within the trisaccharide. A computational study was undertaken, from which low energy conformations, as well as, dihedral angles that define the glycosidic linkages were identified.

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In the present work we report a rapid microwave irradiation-assisted chemical synthesis technique for the growth of nanoparticles, nanorods, and nanotubes of a variety of metal oxides in the presence of an appropriate surfactant (cationic, anionic, non ionic and polymeric), without the use of any templates. The method is simple, inexpensive, and helps one to prepare nanostructures in quick time, measured in seconds and minutes. This method has been applied successfully to synthesize nanostructures of a variety of binary and ternary metal oxides such as ZnO, CdO, Fe2O3, CuO, Ga2O3, Gd2O3, ZnFe2O4, etc. There is an observed variation in the morphology of the nanostructures with changes in different process parameters, such as microwave power, irradiation time, identity of solvent, type of surfactant, and its concentration.