Multipolarity of some transitions in the96Zr(p,n γ e)96Nb reaction

The conversion electron andγ-ray spectra of the⁹⁶Zr(p, n γ)⁹⁶Nb reaction were measured with Ge(Li) and superconducting magnet transporter Si(Li) spectrometers respectively, at 4MeV bombarding proton energy. The multipolarities of some transitions were determined and conclusions were drawn on the spins and parities of the excited states of⁹⁶Nb.     

Immobilization of pig muscle aldolase on a silica-based support

Pig muscle aldolase was covalently attached to a silica-based support possessing aldehyde functional groups. The activity of the immobilized enzyme was 37 U/g solid, and the specific activity calculated on a bound protein basis was 1.9 U/mg protein. The optimum pH for the catalytic activity was pH 7.5. The apparent optimum temperature was found to be 45 degrees C. The Km app value of the immobilized aldolase with D-fructose 1,6-diphosphate as substrate was 1.25 X 10(-4) M. The conformational stability was improved by the immobilization. The immobilized aldolase was used for the continuous splitting of D-fructose 1,6-diphosphate.     

Calorimetric study of the component steps of oscillating chemical reactions

An influence of inorganic compounds (Fe₂O₃, ZnO, PbO, CaCO₃ and K₂CO₃) on the blast furnace coke thermal oxidation in the air and in the CO₂atmosphere was investigated by means of thermal analysis. A catalytic effect showed itself at the oxidation in the air, especially with PbO and K₂CO₃. These compounds bring the oxidation starting temperature and activation energy down and increase the reaction rate constant most distinctly. The PbO and K₂CO₃ actions differ in their mechanisms. K₂CO₃ accelerates particularly the amorphous coke fractions oxidation. In the CO₂ atmosphere an important catalytic effect occurred only with K₂CO₃. The PbO catalytic influence is less distinct. This revised version was published online in July 2006 with corrections to the Cover Date.     

Nickel–cobalt hydroxide catalysts for the cycloaddition of carbon dioxide to epoxides

Research on Chemical Intermediates - Nickel and cobalt bimetallic hydroxides, in which both metal cations present the same oxidation state, were synthesized and characterized by XRD, TGA, TEM, XPS,...     

Formation and Photoinduced Electron Transfer in Porphyrin- and Phthalocyanine-Bearing N-Doped Graphene Hybrids Synthesized by Click Chemistry

Graphene doped with heteroatoms such as nitrogen, boron, and phosphorous by replacing some of the skeletal carbon atoms is emerging as an important class of two-dimensional materials as it offers the much-needed bandgap for optoelectronic applications and provides better access for chemical functionalization at the heteroatom sites. Covalent grafting of photosensitizers onto such doped graphenes makes them extremely useful for light-induced applications. Herein, we report the covalent functionalization of N-doped graphene (NG) with two well-known electron donor photosensitizers, namely, zinc porphyrin (ZnP) and zinc phthalocyanine (ZnPc), using the simple click chemistry approach. Covalent attachment of ZnP and ZnPc at the N-sites of NG in NG−ZnP and NG−ZnPc hybrids was confirmed by using a range of spectroscopic, thermogravimetric and imaging techniques. Ground- and excited-state interactions in NG−ZnP and NG−ZnPc were monitored by using spectral and electrochemical techniques. Efficient quenching of photosensitizer fluorescence in these hybrids was observed, and the relatively easier oxidations of ZnP and ZnPc supported excited-state charge-separation events. Photoinduced charge separation in NG−ZnP and NG−ZnPc hybrids was confirmed by using the ultrafast pump-probe technique. The measured rate constants were of the order of 10¹⁰ s,⁻¹ thus indicating ultrafast electron transfer phenomena.     

Thermal characterization of solar salts from north of Chile and variations of their properties over time at high temperature

The current study has conducted a wide-ranging characterization, under high-temperature conditions, of a new ternary and quaternary heat transfer fluid, with the addition of Ca(NO₃)₂ and LiNO₃, two of the solar salt additives with a greater potential for being included in these new formulations proposed for the new generation of concentrated solar power (CSP) plants. In this direction, the present research is focused on viscosity and thermal stability since these salts try to increase the work temperature range in CSP plants. Viscosity tests were analyzed each 10 °C from 130 to 300 °C in order to check the variation in this parameter close to their melting points. Isothermal analysis at 450 and 500 °C was also performed through thermal gravimetric (TG) analysis, measuring any resulting loss of mass in the sample at these temperatures. Results were compared with the behavior in binary solar salt. These tests showed a progressive thermal degradation of salts over the time and the maximum temperature for operation in CSP has been corrected regarding the use of ternary and quaternary molten salts.     

Singularities of Solutions to Quadratic Vector Equations on the Complex Upper Half‐Plane

Let S be a positivity‐preserving symmetric linear operator acting on bounded functions. The nonlinear equation with a parameter z in the complex upper half‐plane ? has a unique solution m with values in ?. We show that the z‐dependence of this solution can be represented as the Stieltjes transforms of a family of probability measures v on ?. Under suitable conditions on S , we show that v has a real analytic density apart from finitely many algebraic singularities of degree at most 3. Our motivation comes from large random matrices. The solution m determines the density of eigenvalues of two prominent matrix ensembles: (i) matrices with centered independent entries whose variances are given by S and (ii) matrices with correlated entries with a translation‐invariant correlation structure. Our analysis shows that the limiting eigenvalue density has only square root singularities or cubic root cusps; no other singularities occur.© 2016 Wiley Periodicals, Inc.     

Biomimetic synthesis of CuInS2 nanoparticles: Characterization,cytotoxicity, and application in quantum dots sensitized solar cells

CuInS₂ (CIS) nanoparticles have unique chemical, toxicological and optoelectronic properties that favor their technological applications. In the present work we report a novel one step biomimetic method for the aqueous synthesis of CIS nanoparticles, that is also low cost and environmentally friendly. This biomimetic method uses only CuSO₄ and InCl₃ as precursor salts, and the biological molecule glutathione as sulfur donor and stabilizer of the nanoparticles (NPs). The reaction is performed at low temperatures, under aerobic conditions and atmospheric pressure. CIS nanoparticles produced by our biomimetic method exhibit fluorescence emission between 650 and 700 nm when excited at 500 nm. A size between 10 and 15 nm was determined by Dynamic light scattering (DLS) and corroborated by electron transmission microscopy. X-ray diffraction analysis (XRD) confirmed the crystalline structure of the CIS NPs produced. Energy Dispersive X-Ray Spectroscopy (EDX) analyses revealed the presence of Cu, In, and S in a 0.6: 1.4: 2 ratio, which has been reported for other CIS NPs in literature. No cytotoxicity of CIS NPs was observed in human OKT6/TERT2 cells and bacteria. Besides, the potential application of biomimetic CIS NPs as photosensitizers in quantum dots sensitized solar cells (QDSSCs) was confirmed. The biocompatibility, spectroscopic properties, and energy harvesting performance in solar cells of the CIS NPs produced by our biomimetic method make them suitable for their use in different biotechnological applications.     

Adsorption and Activation of CO2 on Nitride MXenes: Composition,Temperature, and Pressure effects

The interaction of CO₂ with nitride MXenes of different thickness is investigated using periodic density functional theory-based calculations and kinetic simulations carried out in the framework of transition state theory, the ultimate goal being predicting their possible use in Carbon Capture and Storage (CCS). We consider the basal (0001) surface plane of nitride MXenes with M_n+1N_n (n=1–3; M=Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W) stoichiometry and also compare to equivalent results for extended (001) and (111) surfaces of the bulk rock-salt transition metal nitride compounds. The present results show that the composition of MXenes has a marked influence on the CO₂-philicity of these substrates, whereas the thickness effect is, in general, small, but not negligible. The largest exothermic activation is predicted for Ti-, Hf-, and Zr-derived MXenes, making them feasible substrates for CO₂ trapping. From an applied point of view, Cr-, Mo-, and W-derived MXenes are especially well suited for CCS as the interaction with CO₂ is strong enough but molecular dissociation is not favored. Newly developed kinetic phase diagrams are introduced supporting that Cr-, Mo-, and W-derived MXenes are appropriate CCS substrates as they are predicted to exhibit easy capture at mild conditions and easy release by heating below 500 K.