The Synthesis and Analysis of the Cytotoxicity of Al2O3-Supported Silver Nanoparticles Prepared by the Plasma Chemical Process Initiated by Pulsed MW Radiation in the Al2O3-Ag Powder Mixtures.

An original plasma chemical process initiated by microwave discharge in a mixture of metal and dielectric powders was applied to prepare specific materials, which consisted of microsized spherical particles of aluminum oxide covered with silver nanoparticles. The prepared materials are highly uniform in shape, size distribution, and composition. Their cytotoxicity was investigated using the human cell lines MCF7, HEK293T, A549, and VA-13 and the bacterial strains E. coli JW5503 (ΔtolC) and E. coli K12. Their cytotoxicity was found not to exceed the cytotoxicity of the starting materials. Thus, the prepared materials can be considered highly promising for catalysis and biotechnology applications.

Microwave Simulation Experiments on Regolith (Lunar Dust) Deposition on Stainless Steel.

In this article, results are presented of experiments on depositing charged particles, which imitate the levitating dust on the Moon, on stainless steel. Ensembles of particles are created above the surface of laboratory regolith whose composition and particle size distribution imitate the dust that covers the Moon's surface. Under the action of the gyrotron radiation on regolith, non-linear physical-chemical processes develop (breakdown, chain plasmachemical reactions, and particle scattering by the Coulomb mechanism), which lead to the appearance of a levitating cloud of particles. The simulation experiment is based on the similarity between the processes that develop in the laboratory experiments with regolith and the processes that occur on the Moon during its bombardment by micrometeorites. The effect of the levitating cloud on stainless steel plates is studied and it is shown that regolith particles in the shape of spheroids of different sizes are deposited on the surface of the plates. The dimensions of the deposited particles and the density of their placement depend on the quality of treatment of the plate surface. It is shown that the laboratory-produced dusty plasma can be used in simulation experiments to study the modification of surfaces of different materials for space technology.

An easy-to-use calculating machine to simulate steady state and non-steady-state preparative separations by multiple dual mode counter-current chromatography with semi-continuous loading of feed mixtures.

Multiple dual mode counter-current chromatography (MDM CCC) separation processes with semi-continuous large sample loading consist of a succession of two counter-current steps: with "x" phase (first step) and "y" phase (second step) flow periods. A feed mixture dissolved in the "x" phase is continuously loaded into a CCC machine at the beginning of the first step of each cycle over a constant time with the volumetric rate equal to the flow rate of the pure "x" phase. An easy-to-use calculating machine is developed to simulate the chromatograms and the amounts of solutes eluted with the phases at each cycle for steady-state (the duration of the flow periods of the phases is kept constant for all the cycles) and non-steady-state (with variable duration of alternating phase elution steps) separations. Using the calculating machine, the separation of mixtures containing up to five components can be simulated and designed. Examples of the application of the calculating machine for the simulation of MDM CCC processes are discussed.

Multiple dual mode counter-current chromatography with variable duration of alternating phase elution steps.

The multiple dual mode (MDM) counter-current chromatography separation processes consist of a succession of two isocratic counter-current steps and are characterized by the shuttle (forward and back) transport of the sample in chromatographic columns. In this paper, the improved MDM method based on variable duration of alternating phase elution steps has been developed and validated. The MDM separation processes with variable duration of phase elution steps are analyzed. Basing on the cell model, analytical solutions are developed for impulse and non-impulse sample loading at the beginning of the column. Using the analytical solutions, a calculation program is presented to facilitate the simulation of MDM with variable duration of phase elution steps, which can be used to select optimal process conditions for the separation of a given feed mixture. Two options of the MDM separation are analyzed: 1 - with one-step solute elution: the separation is conducted so, that the sample is transferred forward and back with upper and lower phases inside the column until the desired separation of the components is reached, and then each individual component elutes entirely within one step; 2 - with multi-step solute elution, when the fractions of individual components are collected in over several steps. It is demonstrated that proper selection of the duration of individual cycles (phase flow times) can greatly increase the separation efficiency of CCC columns. Experiments were carried out using model mixtures of compounds from the GUESSmix with solvent systems hexane/ethyl acetate/methanol/water. The experimental results are compared to the predictions of the theory. A good agreement between theory and experiment has been demonstrated.

Reactivity of polynuclear palladium carboxylate complexes towards acetonitrile: synthesis and X-ray study of Pd2(C6H4-o-C(=NH)CH3)2(CH3CO2)2 and Pd5(CH3C(=N)OC(=N)CH3)(NO)(NO2)x(RCO2)7-x.

Reactions of the polynuclear palladium carboxylate complexes (binary palladium carboxylates and palladium nitrosyl carboxylates) with acetonitrile in some common organic solvents are described. It was found that reaction of palladium acetate Pd(3)(µ-CH(3)CO(2))(6) with acetonitrile and benzene leads to the formation of a binuclear complex Pd(2)(C(6)H(4)-o-C(=NH)CH(3))(2)(CH(3)CO(2))(2) containing molecules of orthometallated 1-phenylethanimine formed as a result of C-C-coupling of acetonitrile and benzene. Nitrosyl carboxylate complexes Pd(4)(NO)(2)(RCO(2))(6) promote more complicated transformations of acetonitrile that leads to the formation of coordinated acetimidic anhydride, which was found in Pd(5)(CH(3)C(=N)OC(=N)CH(3))(NO)(NO(2))(x)(RCO(2))(7-x) clusters. Structures of all the complexes contained products of acetonitrile transformations and a new palladium nitrosyl carboxylate Pd(4)(NO)(2)(cyclo-C(6)H(11)CO(2))(6) was studied with XRD. Analysis of the structures allowed finding a "building block" of palladium nitrosyl carboxylate clusters, that is a 4-nuclear metal chain -Pd(µ-RCO(2))(2)Pd(µ-NO)(µ-RCO(2))Pd(µ-RCO(2))(2)Pd-.

Palladium ketonyl carboxylate complexes--potential models of polynuclear intermediates in olefin oxidation: formation and X-ray structure of Pd6(µ-Cl)(2+x)(µ-CF3CO2)4(µ,κ(2)-CH2C(O)CMe3)(6-x) (x = 0, 2).

Reactions of Pd(4)(NO)(4)(CF(3)CO(2))(4) with olefins were studied, this Pd-cluster was shown to promote the oxidation of olefins into ketones, which were found as ketonyl ligands in complex products of the reaction; 6-nuclear palladium clusters with carboxylate and ketonyl ligands Pd(6)(µ-Cl)(x)(µ-CF(3)CO(2))(4)(µ,κ(2)-CH(2)C(O)CMe(3))(6-x) were characterized by XRD analysis.

Well-defined alkylpalladium complexes with pyridine-carboxylate ligands as catalysts for the aerobic oxidation of alcohols.

Neophylpalladium complexes of the type [Pd(CH(2)CMe(2)Ph)(N-O)(L)], where N-O is picolinate or a related bidentate, monoanionic ligand (6-methylpyridine-2-carboxylate, quinoline-2-carboxylate, 2-pyridylacetate or pyridine-2-sulfonate) and L is pyridine or a pyridine derivative, efficiently catalyze the oxidation of a range of aliphatic, benzylic and allylic alcohols with oxygen, without requiring any additives. A versatile method is described which allows the synthesis of the above-mentioned complexes with a minimum synthetic effort from readily available materials. Comparison of the rates of oxidation of 1-phenylethanol with different catalysts reveals the influence of the structure of the bidentate N-O chelate and the monodentate ligand L on the catalytic performance of these complexes.

Palladium(II) carboxylates and palladium(I) carbonyl carboxylate complexes as catalysts for olefin cyclopropanation with ethyl diazoacetate.

Palladium(I) carbonyl carboxylate complexes [Pd(mu-CO)(mu-RCO2)](n) (R = Me, n = 4; R = CMe(3), n = 6) and the corresponding palladium(II) carboxylates (acetate and pivalate) catalyze the cyclopropanation of olefins with ethyl diazoacetate. The performance of these catalysts is similar in terms of selectivity and cyclopropane yields, regardless of the oxidation state of the metal center. However the rates of the cyclopropanation reactions are significantly higher for the acetate based catalysts than for the pivalate derivatives, which suggests that the main catalytic species are carboxylate containing palladium complexes. Kinetic measurements show that reaction rates are independent of the olefin concentration when these are 1-hexene or styrene, but norbornene exerts an inhibitory effect. In spite of this, competition experiments indicate that the cyclopropanation of styrene is 2.2 times as favorable as that of 1-hexene for any of the four catalysts. These observations indicate that while the rate-determining formation of the intermediate palladium carbenoid species is controlled by the catalyst structure, this is followed by a rapid and less specific cyclopropanation step that is not affected by the nature of the carboxylate groups present in the catalyst. An independent test using a 1:1 benzene/cyclohexane mixture of solvents showed that the transfer of ethoxycarbonylcarbene (:C(CO2Et)H) to these molecules is unselective (relative rate of benzene/cyclohexane functionalization approximately 1.8, independent of the catalyst). This result can be interpreted as an indication of the involvement of free ethoxycarbonylcarbene in the carbene transfer step.

NO-disproportionation, promoted by Pd-cluster: formation and X-ray structure of Pd8(micro-CO)4(micro-OOCCMe3)8[micro-N(=O)O-]4.

Interaction of Pd-clusters [Pd(CO)(OCOR)](n) with NO was investigated, these Pd-clusters were found to promote the NO disproportionation into N(2) and NO(2)(-) in mild conditions; an eight-nuclear palladium cluster Pd(8)(micro-CO)(4)(micro-OOCCMe(3))(8)(micro-NO(2))(4) with a new type of structure and an uncommon set of ligands was characterized by X-ray diffraction analysis.