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Nanoparticles attached just above a flat metallic surface can trap optical fields in the nanoscale gap. This enables local spectroscopy of a few molecules within each coupled plasmonic hotspot, with near thousand-fold enhancement of the incident fields. As a result of non-radiative relaxation pathways, the plasmons in such sub-nanometre cavities generate hot charge carriers, which can catalyse chemical reactions or induce redox processes in molecules located within the plasmonic hotspots. Here, surface-enhanced Raman spectroscopy allows us to track these hot-electron-induced chemical reduction processes in a series of different aromatic molecules. We demonstrate that by increasing the tunnelling barrier height and the dephasing strength, a transition from coherent to hopping electron transport occurs, enabling observation of redox processes in real time at the single-molecule level. [ABSTRACT FROM AUTHOR]

The mechanism of magnesia carbothermic reduction was investigated experimentally in a reduction reaction process in vacuum. The thermodynamic calculation results showed that the initial reduction temperature between MgO and C was 1500 K (1227 °C) at 50 Pa. Other reduction reactions did not occur between the temperature 300 K and 1900 K (27 °C and 1627 °C) and 30 to 100 Pa. Based on the analysis of experimental results, the initial reduction reaction temperature was 1553 K (1280 °C), and it matched well with the thermodynamic calculations. The gas-solid reaction between MgO and CO did not occur at 1723 K (1450 °C), 30 to 100 Pa. Therefore, the main reduction reaction was MgO + C = Mg+ CO in vacuum. This reaction belonged to the solid-solid reaction type, the condensing product was obtained in the condensation zone, and the main component of the product was metal magnesium. A little magnesia was also obtained in the condensing product due to the reverse reaction. [ABSTRACT FROM AUTHOR]

COREX is the primary process in the current smelting reduction method. The process has strict coal quality standards. Combustion processes of coal used in the COREX operating system were analyzed using a synchronous thermogravimetric analyzer combined with a mass spectrometer. The microcosmic structure and macerals were observed by an electronic scanning microscope. The qualitative and quantitative determinations of oxygen functional groups, such as phenolic hydroxyl, carboxyl, carbonyl, and methoxy groups were detected by the Fourier Transform Infrared spectrometer (FT-IR) and through chemical analysis methods. In addition, the evolution of the chemical structure and transformation mechanism of organic oxygen functional groups during COREX coal combustion have been thoroughly investigated. This study proposes a new coal-requirement index system and coal blending method, which will increase the expansion of coal selection and decrease the overall usage of coal during COREX. [ABSTRACT FROM AUTHOR]

Feasibility of multidimensional hydrodynamic modeling depends critically on the availability of accurate reduced kinetic mechanisms of physical and chemical processes taking place in the system. Such mechanisms should describe the processes under consideration within a specified error tolerance in the range of initial conditions of interest while keeping the number of species and reactions as small as possible. We have developed an advanced tool for reduction of detailed kinetic mechanisms with a minimal human effort. The tool includes 10 reduction and 2 analysis methods which are based on the results of zero-dimensional modeling. The methods can be combined and applied in sequence. The reduction tool has been implemented as a part the Chemical Workbench computational package and has been tested for a number of large kinetic mechanisms of gas-phase processes. Using this tool, we reduced the mechanism of tar gasification from 177 species and 879 reversible reactions to only 83 species and 278 reactions, while the mechanism of methane combustion initially involving 127 species and 1,206 reactions was reduced to 42 species and 173 reactions. [ABSTRACT FROM AUTHOR]

Results are reported from a study of the dependence of the reduction in the thickness of strip on the main process parameters as the strip is bent in the rolls of a roll-forming machine. The study was performed with the use of the theory of experiment planning. [ABSTRACT FROM AUTHOR]

A spatially nonuniform system in which a first-order chemical reaction occurs is considered. Both the diffusion coefficient and the kinetic coefficient of the reaction are assumed to be dependent on spatial coordinates. An asymptotically valid method is proposed for reducing a diffusion equation (under the described conditions) in the presence of a source (a reaction) to a simple kinetic equation containing a constant kinetic coefficient. A functional is derived that makes it possible to use variational methods for determining the kinetic coefficient. [ABSTRACT FROM AUTHOR]

Published data on the stability of Pu(VI) and Pu(V) in solutions of mineral and organic acids and their salts are analyzed. The hypothesis that Pu(VI) in acid solutions disappears owing to the disproportionation to Pu(VII) and Pu(V) cannot be accepted because of high redox potential of the Pu(VII)/(VI) couple. Plutonium( VI) is reduced owing to radiation-chemical reactions induced by its α-radiation and to the formation of a dimer (so-called excimer) by an excited Pu(VI) ion with an unexcited Pu(VI) ion, which rapidly decomposes to Pu(V) and HO. Plutonium(V) disappears owing to disproportionation and radiation-chemical processes. [ABSTRACT FROM AUTHOR]

The price of iridium currently trends at about half the cost of platinum, the latter being a typical reduction promoter for Co/AlO Fischer-Tropsch (FT) synthesis catalysts in gas-to-liquids (GTL) technology. In the current contribution, both fixed-bed catalytic FT and TPR-EXAFS/XANES experiments were carried out over 0.1% iridium-doped 25% Co/AlO catalysts in order to (1) assess the effectiveness of Ir as a promoter of cobalt oxide reduction and (2) evaluate the effectiveness of the incipient wetness impregnation (IWI) technique for adding the Ir precursor by comparing a catalyst prepared by IWI to one prepared by atomic layer deposition (ALD). Ir was demonstrated to be an effective promoter for facilitating the second step of cobalt oxide reduction, CoO to Co, and the IWI method was found to be superior to ALD. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

We report herein a facile method for the preparation of sodium tungsten bronzes hollow nanospheres using hydrogen gas bubbles as reactant for chemical reduction of tungstate to tungsten and as template for the formation of hollow nanospheres at the same time. The chemical composition and the crystalline state of the as-prepared hollow Na0.15WO3 nanospheres were characterized complementarily, and the hollow structure formation mechanism was proposed. The hollow Na0.15WO3 nanospheres showed large Brunauer–Emment–Teller specific area (33.8 m2 g−1), strong resistance to acids, and excellent ability to remove organic molecules such as dye and proteins from aqueous solutions. These illustrate that the hollow nanospheres of Na0.15WO3 should be a useful adsorbent. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Mechanism reductions of the detailed aqueous phase chemistry mechanism CAPRAM 3.0i are performed. Manual methods and automatic techniques are both applied in order to provide a less computationally intensive mechanism which is operational in regional chemistry transport models (CTMs). The finally reduced mechanism contains less than 200 reactions (4 times smaller than the detailed CAPRAM 3.0i) and describes the main characteristics of inorganic and organic aqueous phase processes occurring in tropospheric warm clouds. Most of the chemical reduction potential is realized in the CAPRAM 3.0i organic chemistry. The number of aqueous phase species decreases from 380 in the full mechanism to 130 in the final reduced version. The calculated percentage deviations between the full and reduced mechanism are on average below 5% for the most important organic and inorganic target compounds such as oxidants, inorganic and organic acids, carbonyls and alcohols. Comparisons of the required CPU times between the full and reduced mechanisms show reductions of approximately 40%. 2-D test simulations with the CTM MUSCAT were performed using prescribed meteorological conditions in order to examine the applicability of the reduced mechanism at regional scale. Simulations with the reduced CAPRAM 3.0i mechanism and a much less complex mechanism with only limited inorganic chemistry (INORG) were compared to evaluate the effects of more detailed chemistry. The model results show large differences in the level of oxidants and the inorganic and organic mass processing. Prospectively, the reduced mechanism represents the basis for studying aerosol cloud processing effects at regional scale with future CTMs and will allow more adequate interpretation of field data. [ABSTRACT FROM AUTHOR]

The electrochemical behavior of Cu30Ni alloy hydride in 1 N NaOH solution was studied. One-shot and cyclic voltammograms, chronocoulometric, amperometric, and potentiometric curves, as well as time variation of the open-circuit (free-corrosion) potential E cor, were measured. Both types of voltammograms show a limiting current plateau, which can be explained by a preceding chemical reaction of the hydride decomposition. It is concluded (from the character of E cor vs. t curves) that the hydride decomposition involves the alloy's copper component activation through the copper oxide reduction with hydrogen. The alloy hydride decomposition rate was determined by using chronocoulometry: V = 4.6 × 10–4 A/cm2. No potential arrest was observed in the E cor vs. t and E vs. t curves, which is due to concurrent reactions of electrochemical and chemical recombination involving hydrogen atoms adsorbed at the alloy surface. [ABSTRACT FROM AUTHOR]