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For countless applications in science and technology, light must be concentrated, and concentration is classically achieved with reflective and refractive elements. However, there is so far no efficient way, with a 2D detector, to detect photons produced inside an extended volume with a broad or isotropic angular distribution. Here, with theory and experiment, we propose to stochastically transform and concentrate a volume into a smaller surface, using a high-albedo Ulbricht cavity and a small exit orifice through cavity walls. A 3D gas of photons produced inside the cavity is transformed with a 50% number efficiency into a 2D Lambertian emitting orifice with maximal radiance and a much smaller size. With high-albedo quartz-powder cavity walls ( ρ = 99.94 % ), the orifice area is 1 / (1 - ρ) ≈ 1600 times smaller than the walls' area. When coupled to a detectivity-optimized photon-counter ( D = 0.015 photon - 1 s 1 / 2 cm ) the detection limit is 110 photon s - 1 L - 1 . Thanks to this unprecedented sensitivity, we could detect the luminescence produced by the non-catalytic disproportionation of hydrogen peroxide in pure water, which has not been observed so far. We could also detect the ultraweak bioluminescence produced by yeast cells at the onset of their growth. Our work opens new perspectives for studying ultraweak luminescence, and the concept of stochastic 3D/2D conjugation should help design novel light detection methods for large samples or diluted emitters. [ABSTRACT FROM AUTHOR]

A thermodynamic modeling of phase diagrams and thermodynamic properties of the La-Co-O system is presented. Special attention is given to the perovskite LaCoO3−δ phase, due to its outstanding practical importance. In addition to phase equilibria, defect chemistry and charge disproportionation of lanthanum cobaltite were considered during the modeling and are discussed with respect to their thermo-chemical and electrochemical applications. Two sets of optimized parameters are obtained, one for high charge disproportionation (2Co3+ → Co2+ + Co4+) and one for low charge disproportionation. By analyzing both oxygen nonstoichiometry and ion distribution results, it is decided that the parameters for low charge disproportionation will be used in the extensions to multi-component system database (e.g. La-Sr-Co-Fe-O). Calculations with the presented thermodynamic database deliver fundamental materials properties for the optimization of technological materials for industrial applications, including SOFC and oxygen membrane. [ABSTRACT FROM AUTHOR]

Abstract: The article presents a two-dimensional comparison of the alternative manufacturing processes of laminates used in food industry packaging. The main aim of the presented study was an assessment of potential environmental impacts occurring during the production of two-layer laminates containing a patented polypropylene film Metallyte™ 28UBW-ES and the hitherto used pap/LDPE/Al/LDPE multilayer laminates. The environmental assessment was supplemented by a cost calculation with special regard to the investment required for the production of the two-layer laminates. In the research both the life cycle assessment and the life cycle cost methods were applied. Based upon the obtained environmental impact indicator and the discounted costs the eco-efficiency indicator was determined. The results of the comparative analysis are shown on a two-dimensional eco-efficiency diagram. Based on the conducted study it was found that replacement of traditional packaging materials by laminates containing the Metallyte™ 28UBW-ES structure is justified. This is illustrated by a higher eco-efficiency indicator. The difference in the costs between the manufacturing processes under analysis is relatively small. However, when it comes to the environmental impact, there is a clear disproportion in favor of the two-layer laminates.Graphical abstract: [ABSTRACT FROM AUTHOR]

The mechanism of the H2O2 disproportionation catalyzed by the manganese catalase (MnCat) KatB was studied using the hybrid density functional theory B3LYP and the quantum chemical cluster approach. Compared to the previous mechanistic study at the molecular level for the Thermus thermophilus MnCat (TTC), more modern methodology was used and larger models of increasing sizes were employed with the help of the high-resolution X-ray structure. In the reaction pathway suggested for KatB using the Large chemical model, the O-O homolysis of the first substrate H2O2 occurs through a μ-η1:η1 coordination mode and requires a barrier of 10.9 kcal/mol. In the intermediate state of the bond cleavage, two hydroxides form as terminal ligands of the dimanganese cluster at the Mn2(III,III) oxidation state. One of the two Mn(III)-OH− moieties and a second-sphere tyrosine stabilize the second substrate H2O2 in the second-sphere of the active site via hydrogen bonding interactions. The H2O2, unbound to the metals, is first oxidized into HO2· through a proton-coupled electron transfer (PCET) step with a barrier of 9.5 kcal/mol. After the system switches to the triplet surface, the uncoordinated HO2· replaces the product water terminally bound to the Mn(II) and is then oxidized into O2 spontaneously. Transition states with structural similarities to those obtained for TTC, where μ-η2-OH−/O2− groups play important roles, were found to be higher in energy. [ABSTRACT FROM AUTHOR]

α-Amino acids (α-AAs) are in extremely high demand in nearly every sector of the food and health-related chemical industries and continue to be the subject of intense multidisciplinary research. The self-disproportionation of enantiomers (SDE) is an emerging and one of the least studied areas of α-AA or enantiomeric properties, critically important for their production and application. In the present work, we report a detailed study of the SDE via achiral, gravity-driven column chromatography for a set of N-acylated, N-carbonylated, N-fluoroacylated, and N-thioacylated α-amino acid esters. As well as thioacylation, attention was paid to the effect of altering the R group of the ester functionality, the side chain, or that of the acyl group attached to the amide nitrogen, whereby it was found that electron-withdrawing groups in the latter moiety had a pronounced effect on the magnitude and behavior of the resulting SDE phenomenon. Intriguingly, in the case of N-fluoroacylated derivatives, by favoring the formation of dimeric associates and effecting a strong bias toward homochiral associates over heterochiral associates, the SDE magnitude was greatly reduced contrary to intuitive expectations. Energy estimates resulted from DFT calculations. [ABSTRACT FROM AUTHOR]

Each of the three new hydrazobenzenes consisting of a hydrazobenzene conjugated with a 5-membered heterocyclic ring (furan or thiophene) at its two para positions, prepared from corresponding azo precursors, was used in the acid-catalyzed benzidine rearrangements. Both rearrangement and disproportionation occurred and product structures were characterized by spectroscopic data such as NMR, MS, and with CHN analysis. We confirm the largest [9, 9]-sigmatropic benzidine-type rearrangement in each case as a prominent pathway accompanied by disproportionation. [ABSTRACT FROM AUTHOR]

2,6-Dimethylnaphthalene (2,6-DMN) is one of the crucial intermediates for the synthesis of polybutylenenaphthalate and polyethylene naphthalate (PEN). The complex synthesis procedure and the high cost of 2,6-DMN production significantly reduce the commercialisation of PEN even though PEN demonstrates superior properties compared with polyethylene terephthalate. 2,6-DMN can be produced by methylation of 2-methylnaphthalene (2-MN) and/or naphthalene, disproportionation of 2-MN, and/or isomerisation of dimethylnaphthalenes (DMNs). In this study, synthesis of 2,6-triad DMN isomers consisting of 2,6-DMN, 1,6-DMN, and 1,5-DMN have been investigated with the disproportionation of 2-MN over unmodified and Zr-modified mesoporous MCM-41 zeolite catalysts. In contrast to other DMN isomers, both 1,5-DMN and 1,6-DMN can be effectively isomerised to be profitable 2,6-DMN. The disproportionation of 2-MN experiments were carried out in a catalytic fixed-bed reactor in the presence of 1 g of catalyst at a temperature range of 350-500 °C and weight hourly space velocity between 1 to 3 h−1. The results demonstrated that mesoporous MCM-41 zeolite catalyst has a selective pore shape for 2,6-triad DMN isomers, which may allow a decrease in the production cost of 2,6-DMN. Additionally, 2,6-DMN was successfully synthesised by the disproportionation of 2-MN over MCM-41 zeolite catalyst. Furthermore, both the conversion of 2-MN and the selectivity of 2,6-DMN were considerably enhanced by the Zr impregnation on MCM-41. [ABSTRACT FROM AUTHOR]

Copper/carbon dot nanohybrids (Cu/CD NHs) were prepared via a facile precipitation method through a disproportionation reaction. The surface characterization was performed by various techniques such as XRD, FTIR and TEM. Then, water-based nanofluids composed of Cu/CD NHs at 0.1 and 0.5 mass% were prepared, and their thermo-physical properties including thermal conductivity, viscosity, density and specific heat were evaluated at various temperatures. The water-based Cu/CD nanofluid demonstrated to be a potential heat transfer fluid with a high stability. It was found that the thermal conductivity can be enhanced by increasing the nanoparticle concentration and temperature. Almost 1.25-fold increase in thermal conductivity has been achieved by raising the temperature up to 50 °C and at the concentration of 0.5 mass%. The heat capacity was found to increase with increasing concentration. Moreover, by increasing temperature the density and viscosity of the as-prepared nanofluid decreased, whereas the heat capacity showed an increasing trend. [ABSTRACT FROM AUTHOR]

The radiolysis of diethylene glycol dimethyl ether (diglyme) in a boiling state has been studied for the first time. Boiling facilitates the cleavage of internal C-O bonds, weakens the cage effect and diglyme regeneration processes, and facilitates the exchange and dimerization reactions of radicals. As compared with radiolysis at room temperature, the amount of unsaturated products of diglyme fragmentation formed during irradiation in the boiling state is smaller by a factor of 4, and the disproportionation products of heavy radicals are found in negligible amounts, if any. The yield of radiolytic decomposition of diglyme under boiling conditions is ∼15 molecule/100 eV, which is higher than that at room temperature by a factor of almost 1.5. [ABSTRACT FROM AUTHOR]

Drywall manufactured in China released foul odors attributed to volatile sulfur compounds. These included hydrogen sulfide, methyl mercaptan, and sulfur dioxide. Given that calcium sulfate is the main component of drywall, one would suspect bacterial reduction of sulfate to sulfide as the primary culprit. However, when the forensics, i.e., the microbial and chemical signatures left in the drywall, are studied, the evidence suggests that, rather than dissimilatory sulfate reduction, disproportionation of elemental sulfur to hydrogen sulfide and sulfate was actually the primary cause of the malodors. Forensic evidence suggests that the transformation of elemental sulfur went through several abiological and microbial stages: (1) partial volatilization of elemental sulfur during the manufacture of plaster of Paris, (2) partial abiotic disproportionation of elemental sulfur to sulfide and thiosulfate during the manufacture of drywall, (3) microbial disproportionation of elemental sulfur to sulfide and sulfate resulting in neutralization of all alkalinity, and acidification below pH 4, (4) acidophilic microbial disproportionation of elemental sulfur to sulfide and sulfuric acid, and (5) hydrogen sulfide volatilization, coating of copper fixtures resulting in corrosion, and oxidation to sulfur dioxide. [ABSTRACT FROM AUTHOR]

Synthesis of ammonium hydroxodisulfitoferriate(III), (diammonium catena-{bis(μ2-sulfito-κO,κO)-μ2-hydroxo-κ2O}ferrate(III) monohydrate) (NH4)2[Fe(OH)(SO3)2]·H2O (compound 1) and its thermal behavior is reported. The compound is stable in air. Its thermal decomposition proceeds without the expected quasi-intramolecular oxidation of sulfite ion with ferric ions. The disproportionation reaction of the ammonium sulfite, formed from the evolved NH3, SO2 and H2O in the main decomposition stage of 1, results in the formation of ammonium sulfate and ammonium sulfide. The ammonium sulfide is unstable at the decomposition temperature of 1 (150 °C) and transforms into NH3 and H2S which immediately forms elementary sulfur by reaction with SO2. The formation and decomposition of other intermediate compounds like (NH4)2SnOx (n = 2, x = 3 and n = 3, x = 6) results in the same decomposition products (S, SO2 and NH3). Two basic iron sulfates, formed in different ratios during synthesizing experiments performed under N2 or in the presence of air, have been detected as solid intermediates which contain ammonium ions. The final decomposition product was proved to be α-Fe2O3 (mineral name hematite). [ABSTRACT FROM AUTHOR]

It has been stated that immobilized nickel nanoparticles catalyze disproportionation and cross-coupling of amines. The influence of the support on the catalysis of these properties in the in plug-flow reactor has been studied. The use of active carbon as the support has been found advantageous for the cross-coupling of amines, whereas alumina was a better support for the disproportionation reaction. [ABSTRACT FROM AUTHOR]

We reported here the preparation, characterization, and catalytic ability of a Fe3O4-supported palladium-carbon (Fe3O4-Pd-C) as an efficient catalyst in disproportionation of gum rosin. The magnetic nanocatalyst was prepared by a simple method and was characterized by FTIR, XRD, TEM, N2 adsorption-desorption, VSM, and atomic absorption analysis. The prepared catalyst displayed excellent activity in disproportionation of gum rosin. The magnetic Fe3O4-Pd-C catalyst was successfully recycled three times with keeping its catalytic performance. The simplicity of the nanocatalyst production method and simple separation and recyclability, on the other hand, make possible the industrial production and application of the catalyst. [ABSTRACT FROM AUTHOR]

Reaction of poorly soluble manganese(II) bis(1-hydroxyethylidene)diphosphonate tetrahydrate Mn(HL) · 4HO with 2-aminoethanol HNCHCHOH in an aqueous solution on heating to 70-80°C causes the initial formation of soluble tris(2-hydroxyethanaminium) manganese(II) bis(1-hydroxyethylidene) diphosphonate Mn(HL) · 3HNCHCHOH · 4HO, which next disproportionates into poorly soluble 2-hydroxyethanaminium manganese(II) (1-hydroxyethylidene)diphosphonate MnHL · HNCHCHOH and metal-cation-free coordination polymer of (1-hydroxyethylidene)diphosphonic acid with 2-aminoethanol. Poorly soluble MnHL · HNCHCHOH can be readily converted into the soluble form by treatment with 2-aminoethanol or 2-amino-2-(hydroxymethyl)propane-1,3-diol HNC(CHOH). [ABSTRACT FROM AUTHOR]

The specific electric conductivity ( σ) and Seebeck coefficient ( S) are measured in electron-doped manganites CaSrLaMnO ( х = 0.4 and y = 0-0.1) in air within temperature ( Т) range 350-1220 K. The new approach is suggested to explain the metallic-like increase of S with T based on combination of a small polaron theory with charge disproportionation and spin direction of manganese cations. The temperature-dependent variations of the charge disproportionation equilibrium constant, concentration, and mobility ( μ) of charge carriers are derived from the experimental data for S( T) and σ( T). The obtained mobility values vary within 0.1-0.55 cm V s. [ABSTRACT FROM AUTHOR]

Cyclodextrin glucanotransferase (CGTase) is an important enzyme with multiple functions in starch utilization. In the present study, a fermentation process for the production of CGTase from Escherichia coli harboring the recombinant plasmid pET28b(+)- CGTase was investigated and optimized. The optimal fermentation and expression conditions were 10.0 g/L glycerol, 20.0 g/L tryptone, and 10.0 g/L yeast extract with an initial pH of 7.0, an IPTG concentration of 0.1 mM and an induction temperature of 28 °C for 10 h. The resulting CGTase activity reached up to 36.4 U/L and was 2.1-fold higher than before optimization. Under these optimal fermentation conditions, the up-scaled fermentation was carried out in a 500-L fermentor, and a CGTase activity of 45.2 U/L was achieved. This study provides a foundation for the industrial production of CGTase. [ABSTRACT FROM AUTHOR]

The electrical conductivity (σ) of CaPrMnO ( х = 0-0.15) manganites with a perovskite-like structure has been measured by the four probe method in air at temperatures ( T) from 320 to 1220 K. The results have been analyzed in terms of a model of small adiabatic polarons. The observed decrease in σ with increasing T is primarily due to the decrease in carrier concentration as a result of Mn disproportionation into Mn and Mn. The polaron mobility ranges from 0.2 to 1.2 cm/(V s) and decreases with increasing praseodymium content. [ABSTRACT FROM AUTHOR]

The principles of mass and charge conservation apply simultaneously to the disproportionation reactions of plutonium. New formulas for the Pu oxidation number can be generated from a bilinear equation. The new formulas are applied to the analysis of experimental errors in reported oxidation-state distributions for plutonium. Three methods of error analysis are illustrated by examples. [ABSTRACT FROM AUTHOR]

Simulation of the resistivity in the normal state of doped LaSrCuO has been performed using a hopping model based on Marcus theory. The results are in substantial agreement with experimental results. At oxidative doping, Cu(III) sites are formed and electron mobility possible due to hopping: Cu(III)Cu(II) → Cu(II)Cu(III) (one-electron exchange). In the underdoped, non-metallic region, the resistivity ( ρ) decreases from almost insulation at T = 0 to a minimum at about T = 100 K. ρ then increases more than linearly with T (∼ T ) in the region 100 < T < 500 K. A photo-induced metal-metal (MM) charge transfer transition at 2 eV 2Cu(II) + h ν→ Cu(I) + Cu(III) is responsible for the strong absorption in the visible spectrum of LaCuO. The down-shift of spectral density with doping ( x) in LaSrCuO depends on the appearance of Cu(III) sites which makes optical as well as thermal one-electron exchange transitions possible with lower energy. Disproportionation occurs spontaneously for x > 0.06, opening up for electron pair formation. Configuration interaction between two-electron states of low chemical potential, but strong vibrational coupling, gives rise to the superconductor and pseudogaps. Data from photo-induced conductivity and absorption spectra are used in the simulation, which gives results in good agreement with experiments. Possible explanations for Raman and MIR absorption suggest themselves. [ABSTRACT FROM AUTHOR]

Metalliferous sedimentary rocks (mudstones, exhalites) associated with the Cambrian precious metal-bearing Lemarchant Zn-Pb-Cu-Au-Ag-Ba volcanogenic massive sulphide (VMS) deposit, Tally Pond volcanic belt, precipitated both before and after VMS mineralization. Sulphur and Pb isotopic studies of sulphides within the Lemarchant exhalites provide insight into the sources of S and Pb in the exhalites as a function of paragenesis and evolution of the deposit and subsequent post-depositional modification. In situ S isotope microanalyses of polymetallic sulphides (euhedral and framboidal pyrite, anhedral chalcopyrite, pyrrhotite, galena and euhedral arsenopyrite) by secondary ion mass spectrometry (SIMS) yielded δS values ranging from −38.8 to +14.4 ‰, with an average of ∼ −12.8 ‰. The δS systematics indicate sulphur was predominantly biogenically derived via microbial/biogenic sulphate reduction of seawater sulphate, microbial sulphide oxidation and microbial disproportionation of intermediate S compounds. These biogenic processes are coupled and occur within layers of microbial mats consisting of different bacterial/archaeal species, i.e., sulphate reducers, sulphide oxidizers and those that disproportionate sulphur compounds. Inorganic processes or sources (i.e., thermochemical sulphate reduction of seawater sulphate, leached or direct igneous sulphur) also contributed to the S budget in the hydrothermal exhalites and are more pronounced in exhalites that are immediately associated with massive sulphides. Galena Pb isotopic compositions by SIMS microanalysis suggest derivation of Pb from underlying crustal basement (felsic volcanic rocks of Sandy Brook Group), whereas less radiogenic Pb derived from juvenile sources leached from mafic volcanic rocks of the Sandy Brook Group and/or Tally Pond group. This requires that the hydrothermal fluids interacted with juvenile and evolved crust during hydrothermal circulation, which is consistent with the existing tectonic model that suggests a formation of the Tally Pond belt volcanic rocks and associated VMS deposits in a rifted arc environment upon crustal basement of the Ediacaran age Sandy Brook Group and Crippleback Intrusive Suite. Combined S and Pb isotope data illustrate that sulphides within the deposit that are proximal to the vent contain a higher proportion of sulphur derived from thermochemical sulphate reduction (TSR), because hydrothermal fluids are enriched in HS derived from TSR. They also have lower radiogenic Pb contributions, than sulphides occurring distal from mineralization. Hence, the TSR S and non-radiogenic Pb composition may provide an exploration vector in exhalites associated with similar VMS environments. [ABSTRACT FROM AUTHOR]

The objectives of the present study are to isolate thiosulfate-degrading bacterium and optimize its degradative conditions including temperature, pH, and thiosulfate concentrations required for bioremediation purposes. A heterotrophic thiosulfate-degrading bacterial strain DT was successfully isolated from saline soil and identified as Altererythrobacter sp. based on its physicochemical properties and 16S rDNA sequence analysis. It was a naturally occurring methionine auxotrophic strain that utilized only peptone, yeast extract, or several amino acids as the sole carbon source. Altererythrobacter sp. DT degraded thiosulfate via a distinctive disproportionation reaction which was characterized by accumulation of sulfate and elemental sulfur at a molar ratio of 1:1. Optimal conditions for both bacterial growth and thiosulfate metabolism were 25-30 °C and pH 6, respectively. In a fed-batch treatment system receiving liquid polysulfide wastewater, a high degradation rate of 407.3 mg SO /(L h) and an elemental sulfur yield of nearly 50% were achieved for immobilized DT cells, indicating great potential of strain DT for future application in the treatment of and microbial production of elemental sulfur from thiosulfate-bearing industrial wastewater. [ABSTRACT FROM AUTHOR]

The kinetics of the transformation of Np(V) into Np(IV) in 0.1 M potassium biphthalate solutions containing 5-74 mM sodium 1,2-cyclohexanediaminetetraacetate (NaCHDTA) or in a 96-97 mM NaCHDTA solution at 25-45°С was studied. The reaction rate at NaCHDTA concentrations in the range 5-60 mM and pH 3.5-5.9 is described by the equation V = k[Np(V)][CHDTA], and at NaCHDTA concentrations in the range 70-100 mM and pH 4.1-5.2, by the equation V = k [Np(V)]. Neptunium(V) forms with the CHDTA ion an activated complex in which Np(V) is reduced to Np(IV). The dimer {Np(V)} forming another activated complex with the CHDTA ion is formed concurrently. The latter complex decomposes along the disproportionation pathway to give Np(IV) and Np(VI). Np(VI) is reduced with the CHDTA ion to Np(V). [ABSTRACT FROM AUTHOR]

Triethoxysilane disproportionation was carried out over anion exchange resins in quantitative conversion under mild conditions (40-55 °C). Using solvent, the reaction afforded only tetraethoxysilane (75 %) and monosilane (25 %) as products, in a reaction time of 3 h. The reaction under solvent-free conditions resulted in 100 % conversion after 2 h at a reduced temperature of 40 °C. Graphical Abstract: [ABSTRACT FROM AUTHOR]

Genome sequence of hyperthermophilic archaeon Pyrobaculum calidifontis revealed the presence of an open reading frame, Pcal_0768, corresponding to a putative 4-α-glucanotranferase belonging to glycoside hydrolases (GH) family 77. We have produced, in Escherichia coli, and purified recombinant Pcal_0768 which exhibited high disproportionation (690 U mg) activity. To the best of our knowledge, this is the highest ever reported activity for any member of family GH77. Maltooligosaccharides, when used as sole substrates, were disproportionated into linear maltooligohomologues. The analysis of the reaction end products revealed no evidence for the production of cycloamyloses. Catalytic activity of the enzyme remained unchanged in the presence or the absence of ionic and nonionic detergents. γ-cyclodextrin, an inhibitor of 4-α-glucanotransferases, did not show any inhibitory effect on Pcal_0768 activity. These properties make Pcal_0768 a potential candidate for starch processing industry. [ABSTRACT FROM AUTHOR]

Ischemia impairs the adenine nucleotide translocase (ANT), which transports ADP and ATP across the inner mitochondrial membrane. We investigated whether ANT1 overexpression has protective effects on ischemic hearts. Myocardial infarction was induced in wild-type (WT) and heart-specific ANT1-transgenic (ANT1-TG) rats, and hypoxia was set in isolated cardiomyocytes. ANT1 overexpression reduced the myocardial infarct area and increased the survival rate of infarcted rats. Reduced ANT1 expression and increased 4-hydroxynonenal modification of ANT paralleled to impaired ANT function in infarcted WT hearts. ANT1 overexpression improved ANT expression and function. This was accompanied by reduced mitochondrial cytochrome C release and caspase-3 activation. ANT1-TG hearts suffered less from oxidative stress, as shown by lower protein carbonylation and 4-hydroxynonenal modification of ANT. ANT1 overexpression also increased cell survival of hypoxic cardiomyocytes and attenuated reactive oxygen species (ROS) production. This was linked to higher stability of mitochondrial membrane potential and lower activity of ROS detoxifying catalase. ANT1-TG cardiomyocytes also showed higher resistance against HO treatment, which was independent of catalase activity. In conclusion, ANT1 overexpression compensates impaired ANT activity under oxygen-restricted conditions. It reduces ROS production and oxidative stress, stabilizes mitochondrial integrity, and increases survival, making ANT1 a component in ROS management and heart protection during ischemia. Key messages: [ABSTRACT FROM AUTHOR]

The structural parameters of the (Σ//C)-YbF, (A//C)-YbF2, (A//D)-YbF, (Ag//D)-YbFYb, (Ag//C)-FYbFYbF, (A//C)-FYbFYbF, (A//C)-YbFYbF, (B//D)-FYbFYbF, (A′//C)-FYbFYbF, and (B//С)-FYbFCeF molecules have been determined. Disproportionation of ytterbium monofluoride (2YbF → YbF + Yb + 0.46 eV) is less exothermic than dimerization (2YbF → YbFYb + 2.10 eV). The bond energy of the ytterbium difluoride molecules in the trans dimer (2.93 eV) exceeds those in the cis dimer (2.86 eV) and the coaxial dimer (1.66 eV). Ytterbium trifluoride dimerizes exothermically (2.95 eV) without spin pairing. The dipole and quadrupole moments of the molecules as well as the charges and spin populations of the atoms and the valence electron configurations of the lanthanides have been calculated. [ABSTRACT FROM AUTHOR]

Metallurgical silicon slag is the by-product of metallic silicon industry. The utilization of silicon slag is very limited due to the absence of related researches. In this work, the oxidation behavior of metallurgical silicon slag was studied by means of phase variation under the non-isothermal and isothermal conditions. The crystal structure and phase composition of silicon slags were investigated by X-ray powder diffraction, simultaneous thermal analysis, scanning electron microscopy and thermogravimetry. During the oxidation process, the CO emission was progressively enhanced with increasing the oxidation temperature, and the exothermic oxidation primarily occurred above 700 °C. The non-isothermal oxidation of silicon slag powder was a complicated process, involving the oxidation, crystal precipitation and disproportionation processes. The graphite phase was completely removed at 1000 °C. The SiC and cristobalite phases greatly increased at 750 °C and decreased with further increasing the oxidation temperature. For the isothermal oxidation, the Si and SiC phases generally reduced with increasing the soaking time. The cristobalite and tridymite phases increased with the oxidation time. The mass change in slag powders suggested that the isothermal oxidation process consisted of the initial redox reaction and subsequent oxidation reaction. [ABSTRACT FROM AUTHOR]

Disproportionation reactions can noticeably change the acidity of a plutonium solution. The estimation of the pH change depends on the the Pu concentration, the initial oxidation-state distribution, the initial pH of the solution, and the values of three equilibrium constants. The method can be used to estimate the minimum Pu concentration that produces a specified change in the solution acidity. The results can be checked. [ABSTRACT FROM AUTHOR]

Mutual interaction of redox pairs resulting in the origin or decomposition of a metal phase is analyzed based on the concept of intrinsic oxygen fugacity. Reactions are suggested that may be responsible for the synthesis (or decomposition) of submicrometer-sized metal nuggets when experimental melts are quenched and can explain the possible crystallization of Pt-Fe alloys when basaltic melts cool and elucidate the nature of color of Au-bearing ruby glass. Possible disproportionation reactions of certain lower oxides into a higher oxide and respective metal in cooled silicate melts are discussed. [ABSTRACT FROM AUTHOR]

The use of methane and acetate as electron donors for biological reduction of thiosulphate in a 5-L laboratory membrane bioreactor was studied and compared to disproportionation of thiosulphate as competing biological reaction. The reactor was operated for 454 days in semi-batch mode; 30 % of its liquid phase was removed and periodically replenished (days 77, 119, 166, 258, 312 and 385). Although the reactor was operated under conditions favourable to promote thiosulphate reduction coupled to methane oxidation, thiosulphate disproportionation was the dominant microbial process. Pyrosequencing analysis showed that the most abundant microorganisms in the bioreactor were phototrophic green sulphur bacteria (GSB) belonging to the family Chlorobiaceae and thiosulphate-disproportionating bacteria belonging to the genus Desulfocapsa. Even though the reactor system was surrounded with opaque plastic capable of filtering most of the light, the GSB used it to oxidize the hydrogen sulphide produced from thiosulphate disproportionation to elemental sulphur. Interrupting methane and acetate supply did not have any effect on the microbial processes taking place. The ultimate goal of our research was to develop a process that could be applied for thiosulphate and sulphate removal and biogenic sulphide formation for metal precipitation. Even though the system achieved in this study did not accomplish the targeted conversion using methane as electron donor, it does perform microbial conversions which allow to directly obtain elemental sulphur from thiosulphate. [ABSTRACT FROM AUTHOR]

The textural, acidic, and catalytic properties of MFI zeolite-based micro-mesoporous materials synthesized by recrystallization have been studied. It has been shown that recrystallization does not affect the chemical composition of the samples, but it leads to a change of their porous structure and acid properties. All of the materials have exhibited stable activity in the toluene disproportionation reaction. In the presence of the micro-mesoporous materials obtained by recrystallization under mild conditions, the toluene conversion increases by more than three times compared with the parent MFI zeolite, reaching 33 wt %. Differences in the texture and acid properties of the samples do not affect the composition of the toluene disproportionation products. The enhancement of the catalytic activity of recrystallized MFI zeolites is assumed to be due to both the presence of through mesopores and the facilitation of access to strong acid sites. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to investigate how the disproportionation process can be impacted by the properties of the salt, specifically pH. Methods: Five miconazole salts and four sertraline salts were selected for this study. The extent of conversion was quantified using Raman spectroscopy. A mathematical model was utilized to estimate the theoretical amount of conversion. Results: A trend was observed that for a given series of salts of a particular basic compound (both sertraline and miconazole are bases), the extent of disproportionation increases as pH decreases. Miconazole phosphate monohydrate and sertraline mesylate, although exhibiting significantly different pH values (more than 2 units apart), underwent a similar extent of disproportionation, which may be attributed to the lower buffering capacity of sertraline salts. Conclusion: This work shows that the disproportionation tendency can be influenced by pH and buffering capacity and thus highlights the importance of selecting the appropriate salt form during the screening process in order to avoid salt-to-free form conversion. [ABSTRACT FROM AUTHOR]

The kinetics of the Np(V) disproportionation in 0.1 M potassium hydrogen phthalate + 30 mM EDTA solutions at 25-45°C was studied by spectrophotometry. The reaction rate at pH in the range 3.0-5.0 is described by the equation −d[Np(V)]/d t = k[Np(V)], where k = k[H]. In solution with pH 4.01 at 25°C, k = 3.39 × 10 L mol s. The complexes of NpO with HY form a dimer, which forms an activated complex with the H ion. Decomposition of the activated complex yields Np(IV) and Np(VI). Neptunium(VI) bound with Y undergoes intramolecular reduction to Np(V). [ABSTRACT FROM AUTHOR]

The pseudo-equilibrium concentrations of the H, IO, and HOI ions, kinetically very important species in the disproportionation reaction of iodous acid, have been determined from the equilibrium dissociation reactions of sulfuric and iodous acids in the quasi-stationary state. The values observed were higher than the concentration of the protonated ion of hypoiodous acid. [ABSTRACT FROM AUTHOR]

Thermobifida fusca is a mesothermophilic organism known for its ability to degrade plant biomass and other organics, and it was demonstrated that it represents a rich resource of genes encoding for potent enzymes for biocatalysis. The thermostable catalase from T. fusca has been cloned and overexpressed in Escherichia coli with a yield of 400 mg/L. Heat treatment of disrupted cells at 60 °C for 1 h resulted in enzyme preparation of high purity; hence, no chromatography steps are needed for large-scale production. Except for catalyzing the dismutation of hydrogen peroxide, TfuCat was also found to catalyze oxidations of phenolic compounds. The catalase activity was comparable to other described catalases while peroxidase activity was quite remarkable with a k of nearly 1000 s for catechol. Site directed mutagenesis was used to alter the ratio of peroxidase/catalase activity. Resistance to inhibition by classic catalase inhibitors and an apparent melting temperature of 74 °C classifies this enzyme as a robust biocatalyst. As such, it could compete with other commercially available catalases while the relatively high peroxidase activity also offers new biocatalytic possibilities. [ABSTRACT FROM AUTHOR]

Substituent exchange at the silicon atom between chloro(phenyl)silanes (PhSiCl, MePhSiCl, PhSiCl) and chloro(ethyl)silanes (EtSiCl, EtSiCl, EtSiCl, EtSi) in the presence of aluminum chloride has been studied. The examined compounds, except for PhSiCl and EtSi, react fairly readily to give chloro(ethyl)-(phenyl)silanes in up to 48-52% yield. A probable mechanism has been proposed. [ABSTRACT FROM AUTHOR]

The behavior of An(V) (An = Np, Pu, and Am) in aqueous solutions of dipicolinic acid (in particular, the resistance to disproportionation) was studied. Taking these data into account, procedures were developed for preparing crystalline An(V) dipicolinates. Crystals of Li[AnO(DPA)]· nHO ( n = 4 and 6) of X-ray quality were prepared from aqueous solutions with pH 2-3. The trends in variation of the bond lengths in the complex compounds of An(V) and An(VI) with dipicolinic acid, caused by actinide contraction, were analyzed. [ABSTRACT FROM AUTHOR]

The polar order along the c axis is revealed in GdMnO and GdCeMnO at T ≤ T ≈ 160 K for the first time. This polar order is induced by the charge disproportion in the 2D superstructures emerged due to phase separation. The dynamic state with restricted polar domains of different sizes is found at T > T which is typical of the diffuse ferroelectric phase transition. At the lowest temperatures ( T < 40 K) two polar orders of different origins with perpendicular orientations (along the b and c axes) coexist. The 1D superlattices studied by us earlier in the set of RMnO multiferroics are the charged domain walls which separate of these polar order domains. [ABSTRACT FROM AUTHOR]

Equations representing disproportionation reactions should be numerically verifiable. Comprehensive, balanced equations for plutonium disproportionation reactions can be verified in several ways. Overall equations for Pu disproportionation reactions do not meet all the requirements. [ABSTRACT FROM AUTHOR]

The crystallization behavior of PEOs with molecular weight of 10k and 200k as well as their blends was studied in details. The results show that the lower molecular weight PEO crystallizes with faster crystallization rate as judged from a shorter time for completing the crystallization. On the other hand, the higher molecular weight PEO crystallizes at relatively higher temperature, indicating an early start of crystallization compared with the lower molecular weight one. The blends of these two PEOs with different blend ratios always cocrystallize during the cooling processes. It is confirmed that mixing of the 10k PEO with the 200k one is in favor of the crystallization of the system. This is not only demonstrated by the early start of the crystallization at higher crystallization temperature, and also a faster crystal growth of the blend with respect to the 200k PEO. The crystallization of the blends at higher temperature is caused by an early start of nucleation and an increment of nucleus density. This may originate from the density fluctuation of the blend and a reduction in energy barrier for nucleation. Moreover, it is found that the crystallinity of the 10k PEO rich blends increases with increasing concentration of the 10k PEO. This is caused by the solvent effect of the 10k PEO toward the 200k PEO. On the other hand, the crystallinity of the 30/70 (10k/200k) PEO blend is decreased a little bit. This may be a balanced result of the improved crystallization of the 200k PEO at the expense of the high crystallization ability of the 10k PEO. [ABSTRACT FROM AUTHOR]

The bioreduction and disproportionation of cyclohex-2-enone catalyzed by Old Yellow Enzyme 1 was investigated in presence of organic (co)solvents. Whereas the NADH-dependent bioreduction activity strongly decreased at elevated co-solvent concentrations due to the insolubility of the nicotinamide-cofactor, the NADH-free disproportionation was significantly improved in water-immiscible organic co-solvents at 90 % (v/v) with near-quantitative conversion. This positive effect was attributed to removal of the inhibiting co-product, phenol, from the enzyme's active site. The best co-solvents show high lipophilicity (logP) and a high potential to solubilize phenol (K). As a predictive parameter, the ratio of logP/K should be preferably ≥100. [ABSTRACT FROM AUTHOR]

Local maxima in the fractions of the trivalent and hexavalent oxidation states are inherent in the algebra of Pu disproportionation reactions. A new method predicts the pH and the oxidation-state fractions at maximum. Tabulated results illustrate the effects of the Pu oxidation number and Pu(IV) hydrolysis on the maxima. This method suggests a new laboratory approach for discovering Pu oxidation-state maxima. [ABSTRACT FROM AUTHOR]

A systematic study on the influence of reaction time and temperature during transformation reaction of m-, o- and p-xylene has been carried out over HZSM-5 catalyst using a riser simulator reactor system. The product selectivities have revealed that isomerization and disproportionation are the primary reactions. A higher conversion was observed for p-X as compared to that of m-X and o-X at all temperatures and all concentrations of ZSM-5. The highest selectivity of isomerization (100 %) was observed for p-X and o-X at 200 °C over 20 % ZSM-5, whereas the highest disproportionation selectivity (25 %) was observed for m-X at 400 °C over 10 % ZSM-5. The order of reactivity was observed to be dependent upon the concentration of ZSM-5. When ZSM-5 concentration was 10 % the order of reactivity was p-X > m-X > o-X, whereas at a higher concentration of ZSM-5 the order of reactivity was p-X > o-X > m-X. The experimental results have been modeled also using quasi-steady-state approximation. Kinetic parameters for o-X, m-X and p−X conversions into isomerization and disproportionation products were calculated using the catalyst activity decay function based on the time on stream. The apparent activation energies for disproportion as well as for the combined isomerization reactions over 10 % ZSM-5 catalyst were found to decrease as follows: E > E > E. It was also noted that when concentration of ZSM-5 was increased from 10 to 20 % the activation energies were increased for isomerization reactions but decreased for disproportionation reactions. [ABSTRACT FROM AUTHOR]

Bacillus circulans T-3040 produces cycloisomaltooligosaccharide glucanotransferase (CITase) and cycloisomaltooligosaccharides (cyclodextrans, CIs) when it is grown in media containing dextran as the carbon source. To investigate the effects of carbon sources on CITase activity, B. circulans T-3040 was cultured with glucose; sucrose; a mixture of isomaltose, isomaltotriose, and panose (IMOs); a mixture of maltohexaose and maltoheptaose (G67); dextrin (average degree of polymerization = 36); dextran 40; and soluble starch. In addition to dextran 40, CIs were produced when the T-3040 strain was grown in media containing soluble starch as the sole carbon source. CITase production was induced by dextran 40, IMOs, and soluble starch but not by G67 or dextrin, which suggests that α-1,6 glucosidic linkages are required for CITase induction. Although CITase was induced by IMOs, no CIs were produced in the culture. CI-producing activity in the presence of soluble starch as the substrate (SS-CITase activity) was observed only in cultures containing dextran 40 or soluble starch. The production of CITase was significantly unaffected by glucose addition, but SS-CITase activity almost completely disappeared after glucose addition. A 135-kDa protein was found to contribute to CI formation from starch in the presence of CITase. This protein had a disproportionation activity with maltooligosaccharides, and its induction and inhibition system may be different from those of CITase. [ABSTRACT FROM AUTHOR]

The deposition of tetranuclear potassium carbonylruthenate K[Ru(CO)] onto carbon Sibunit, SiO, γ-AlO, and MgO followed by the thermal decomposition of the supported anionic cluster at 300 °C in an H or Ar flow leads to systems capable of catalyzing the disproportionation of cyclohexa-1,3-diene and cyclohexa-1,4-diene. The reactions proceed at room temperature to form mixtures of benzene and cyclohexene, benzene, cyclohexene, and cyclohexane, or benzene and cyclohexane. The catalytic systems developed are also active in cyclohexene disproportionation to benzene and cyclohexane at 100-130 °C. [ABSTRACT FROM AUTHOR]

The oxidation of the earlier synthesized [4,6-di- tert-butyl- N-(2,6-diisopropylphenyl)- o-amidophenolato]methylgallium( iii) ( 1a) and [4,6-di- tert-butyl- N-(2,6-diisopropylphenyl)- o-amidophenolato]iodogallium( iii) ( 1b) by different reagents, such as mercury( ii) salts, molecular iodine, and tetramethylthiuram disulfide, was studied. The oxidation of the starting diamagnetic compounds gives pentacoordinated gallium( iii) bis- o-iminosemiquinolates 4-7 as the major products, which are generated as a result of the further disproportionation of intermediate monoradical tetracoordinated metal complexes. [ABSTRACT FROM AUTHOR]

The mechanism of the disproportionation of 2,5-diethyl-3,4-dihydro-2 H-pyran-2-carbaldehyde in the Cannizzaro reaction in ethanol was studied by quantum-chemical modeling. The geometry was optimized by the semiempirical RM1 method in the unrestricted Hartree-Fock approximation, and the heats of formation of the reagents and transitional states were calculated. Two possible hydride transfer reaction paths are presented: through the formation of a transition state with one-center interaction or through a transition state with two-center interaction. The theoretically calculated values of the thermodynamic parameters agree with the experimental values and confirm the hydride transfer mechanism. [ABSTRACT FROM AUTHOR]

Phosphorylation of naphthodiols with hexaisopropyl- and hexabutyltriamides of phosphorous acid was studied for the first time. The features of these reactions were considered. A comparative analysis of the properties of the synthesized naphthophosphacyclophanes and dismutation of bisamidophosphites was performed. [ABSTRACT FROM AUTHOR]

We have identified the main reactions responsible for the formation of (WO) ( n = 2-5) oxides. In the range T = 2000-2500 K, all of the (WO) oxides result from WO disproportionation or from reactions of WO with the components of the system (W, O, and O). Reactions between WO, WO, and WO, as well as W oxidation and WO disproportionation, yield minor amounts of (WO). WO prevails over the other (WO) oxides because of (WO) ( n = 3-5) decomposition and reactions between them and other components. [ABSTRACT FROM AUTHOR]

The paper determines the phase composition of the ground KS37 alloy after conventional and solid hydrogenation and disproportionation (SmCo being the main phase and SmCo the impurity phase) at a hydrogen pressure of 0.1-0.4 MPa and at temperatures up to 950°C for 5 h. It is established that products resulting from grinding of the SmCo phase interact with hydrogen to 560°C to form SmCo and unidentified phases. The SmCo phase disproportionates in the temperature range 560-650°C and pressure range 0.1-0.4 MPa for 2 h. Recombination at 650-950°C leads to the SmCo, SmCo, and SmCo phases. The SmCo content of the recombined alloy is the highest at 950°C. It is shown that grinding in hydrogen prior to hydrogenation, disproportionation, desorption, and recombination accelerates the disproportionation reaction owing to the formation of defects during grinding. The high-temperature recombination of the SmCo phase in hydrogen is confirmed. [ABSTRACT FROM AUTHOR]