Yield and quality of bacterial cellulose from agricultural waste

Cellulose - The global abundance and availability of oat hulls make them a promising feedstock to produce a unique type of cellulose, the bacterial one. This is the first study examining how a...     

Magnetohydrodynamic thermochemotherapy and MRI of mouse tumors

A dextran-ferrite magnetic fluid was successfully tested as magnetic resonance imaging (MRI) contrast agent. The same magnetic fluid was then combined with Melphalan, a chemotherapeutic drug, and used for magnetohydrodynamic thermochemotherapy of different tumors. The placement of the tumors in an AC magnetic field led to hyperthermia at 46 °C for 30 min. In combination with tumor slime aspiration, a 30% regression of ∼130 mm³ non-metastatic P388 tumors in BDF₁ mice was reached, together with a life span increase of 290%. The same procedure associated with cyclophosphamide treatment of ∼500 mm³ metastases tumor increased the animal's life span by 180%.     

Energy-efficient dehydrogenation of methanol in a membrane reactor: a mathematical modeling

A two-dimensional non-isothermal stationary mathematical model of the catalytic membrane reactor for the process of methanol dehydrogenation is described. Copper supported on the carbonaceous support was considered as a catalyst. The reaction of methanol dehydrogenation was thermodynamically conjugated with a reaction of hydrogen oxidation taking place in a shell side of the membrane reactor. The effects of various parameters on the methanol conversion and the methyl formate yield have been calculated with the developed model and discussed. Two different types of heating the gas flow were considered and compared. In the case of conjugated dehydrogenation process, the methyl formate yield reaches 77%, when the reactor outer wall was heated up to 150 °C. When the inlet gas flows in the tube and shell sides were heated up to 100 and 83 °C, correspondingly, the yield was 72%.     

Synthesis of N-aminopyrazoles by Fe(II)-catalyzed rearrangement of 4-hydrazonomethyl-substituted isoxazoles

A novel effective method is reported for the preparation of 1-amino-1H-pyrazole-4-carboxylic acid derivatives by Fe(II)-catalyzed rearrangement of isoxazoles having (2,4-dinitrophenylhydrazono)methyl substituent at C4. The reaction proceeds smoothly for both E and Z isomers of 4-(hydrazonomethyl)isoxazoles, and this means it is not necessary to separate mixtures of E/Z-isomers of the hydrazones prepared by reaction of 5-methoxy/pirrolidino-4-carbonylisoxazoles and 2,4-dinitrophenylhydrazine. The rearrangement proceeds via the formation of an aziridine intermediate which can be isolated in certain cases. The 2-nitro group in the synthesized 1-[(2,4-dinitrophenyl)amino]-1H-pyrazole-4-carboxylic esters can be selectively reduced in two steps via acylation of the amino group followed by hydrogenation-deacylation using H₂-Pd/C.     

In situ EPR study of chemoselective hydrogenation of nitroarenes on Au/Al2O3 catalyst

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Hydroxyl-functionalized alkyl-terminated silsesquioxanes as surface modificators of friction geomodifiers

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DFT study of small aluminum and boron hydrides: isomeric composition and physical properties

The structure, energetics, and physical properties, including rotational constants, characteristic vibrational temperatures, dipole moment, static polarizability, HOMO-LUMO gap, formation enthalpy and collision diameter of different isomeric forms of atomic Al _n H _m and B _n H _m clusters with n = 1..4 and all feasible m numbers are studied within the density functional theory framework. The search of isomer structures has been accomplished using multistep hierarchical algorithm. Temperature dependences of thermodynamic functions (enthalpy, entropy and specific heat capacity) have been calculated both for the individual isomers and for the ensemble of isomers with equilibrium composition for each class of clusters, taking into account the anharmonicity of cluster vibrations and the contribution of excited electronic states. The prospects of the application of small atomic Al _n H _m and B _n H _m clusters as the components of energetic and hydrogen storage materials are also discussed.     

Synthesis, structure and properties of novel N-thiophosphorylated derivatives of 1,3-dihydro-2H-benzimidazol-2-imine and imidazolidine-2-imine

The reaction of bis-thiourea o-C₆H₄[NHC(S)NHP(S)(Oi-Pr)₂]₂ (1) with iodine, KOH and ClCH₂C(O)OCH₃ leads to O,O′-diisopropyl-1,3-dihydro-2H-benzimidazol-2-ylideneamidothiophosphate (2) formation. The complex of the potassium salt of compound 2 with 18-crown-6, having the composition [K(18-crown-6)L], has been synthesized. Bis-thiourea [CH₂NHC(S)NHP(S)(Oi-Pr)₂]₂ (6) forms a stable potassium salt, which oxidation by iodine leads to a product of heterocyclization, O,O′-diisopropyl-(1-{[(diisopropoxyphosphorothio)amino]carbonothioyl}imidazolidine-2-ylidene)amidothiophosphate (8), in which one of the thiourea fragments is kept.     

Effect of gleysation on remobilization of radionuclides in waterlogged soils

Joint leaching of iron and other macro- and microelements including radionuclides from radioactively contaminated floodplain soil of the Yenisei River is studied on miniecosystems. In developing anaerobic conditions, the redox potential E_h decreased to +140 mV, causing partial reduction of iron and solubilisation of iron hydrous oxide and organomineral films of the soil. Leaching of stable elements and radionuclides with water proceeds parallel to that of iron. To accelerate reductive mobilization of iron, 0.4% aqueous ascorbic acid was used instead of water as the leaching liquid phase. In this case, E_h approached –60 mV, and the leaching of stable and radioactive elements considerably increased, the effect being most pronounced for plutonium. To cite this article: E.K. Legin et al., C. R. Chimie 7 (2004).

Résumé

Effet du passage en milieu anaérobie sur la mobilisation des radionucléides dans les sols humides. La lixiviation simultanée du fer et d’autres éléments de sols contaminés de la vallée de la rivière Yénései a été étudiée. En imposant des conditions anaérobies, le potentiel redox chute à 140 mV, causant une réduction partielle du fer trivalent et la solubilisation de l’hydroxyde de fer et du film organominéral du sol. Les lixiviations du fer, des autres éléments et, par conséquent, des radionucléides contaminant le sol vont de pair. Pour accélérer la mobilisation réductive du fer, une solution d’acide ascorbique à 0,4% a été utilisée à la place de l’eau. Dans ces conditions, la valeur de E_h approche –60 mV et la lixiviation des éléments augmente considérablement, cet effet étant plus prononcé pour le plutonium. Pour citer cet article : E.K. Legin et al., C. R. Chimie 7 (2004).