(Fe(III)(OH(2))(2))(3)(A-alpha-PW(9)O(34))(2)](9-) on cationic silica nanoparticles,a new type of material and efficient heterogeneous catalyst for aerobic oxidations

Polyoxometalates (POMs) electrostatically bind to silica nanoparticles coated with cationic aluminum oxide "(Si/AlO2)n+" to form a new type of material (the anionic POMs replace Cl- counterions associated with the cationic surface sites). Association of a new approximately D3h POM of formula [(FeIII(OH2)2)3(A-alpha-PW9O34)2]9- (1) with the cationic nanoparticles (to form "K81/(Si/AlO2)") was studied in detail. Elemental analysis, particle sizes from both laser light scattering and TEM before and after association of 1, the size of 1 from X-ray crystallography, and other methods provide mutually consistent data that indicate about 58 K8[(FeIII(OH2)2)3(A-alpha-PW9O34)2]- monoanions associate with the average nanoparticle (diameter of the K81/(Si/AlO2) product = approximately 17 nm). While heterogeneity of the cationic sites and roughness of the (Si/AlO2)n+ surfaces make the associated POMs structurally nonuniform, the equivalent of approximately 1 monolayer of 1 is present in K81/(Si/AlO2). Remarkably, while 1, the precursor (Si/AlO2)n+, and the components of 1, each alone, are inactive as catalysts for O2/air-based oxidation of sulfides or aldehydes in solution, K81/(Si/AlO2) is an active catalyst for both reactions (facile reaction with air at low temperature).     

Cupric decamolybdodivanadophosphate. A coordination polymer heterogeneous catalyst for rapid, high conversion, high selectivity sulfoxidation using the ambient environment

A new type of coordination network polymer involving the redox-active polyanion, PV(2)Mo(10)O(40)(5)(-), and bridging -Cu(II)(OH(2))(4)- units, [[(Cu(II)(OH(2))(4))(3)(OH)]PV(2)Mo(10)O(40)](n)() (1), has been characterized by X-ray crystallography and several other methods. It is the first efficient heterogeneous (insoluble) catalyst for selective and rapid sulfoxidation using only the ambient environment (air at room temperature). Catalytic activity is enhanced by soluble nitrate in nontoxic perfluoropolyether (PFPE) media.     

Systematic procedure for reduction of kinetic mechanisms of complex chemical processes and its software implementation

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.     

Calculating fluid pressure on piston with constant expansion rate

We consider the problem of the expansion at a constant rate of a planar, cylindrical, or spherical piston in a compressible fluid and calculate the fluid pressure on the piston as a function of its velocity. We consider the solution of the self-similar problem of piston expansion in a compressible fluid at a constant velocity. A similar problem has been solved by Kochina and Mel'nikova in On the expansion of a piston in water, PMM, vol. 23, no. 1, 1959. Results are presented of the numerical solution of this problem for certain values of the parameters characterizing the problem, and the variation of the pressure on the piston as a function of the piston velocity is approximated by several empirical formulas. For the cases of the cylindrical and spherical pistons the approximate analytic relations for the pressure on the piston as a function of the velocity are compared with the numerical solution of the self-similar problem of piston expansion.     

Mass of the higgs versus fourth generation masses

Double sign inversion of the topological charge of an optical vortex was predicted and observed experimentally for a beam focused by a cylindrical lens. Beam evolution after passing through the lens is analyzed by the decomposition of the orbital angular momentum into the “vortical” and “mechanical” components. Topological reactions in the beam wave resulting in the sign inversion of the optical vortex upon the intersection of the wave-front edge dislocation are considered.     

Mitotic and amitotic cell replication in malignant melanoma: the role of subdivisional cell replication

It is widely assumed that significant mitotic activity is typical of malignant melanoma and many believe that significant mitotic activity is essential for this diagnosis. We have studied mitotic activity in 205 malignant melanomas and have found that mitotic activity is often minimal or absent, even in malignant melanomas which have recurred or metastasized. Based on our previous work suggesting that new cells can form from nucleoli via nucleolar stalks, we also studied nucleolar stalks in our cases. These were present in greater numbers than mitoses and help explain the anomaly of infrequent mitoses in a highly malignant neoplasm.     

Fine tuning the reactivity of corrole-based catalytic antioxidants

In order to determine the electronic factors that may affect the catalytic antioxidant activity of water-soluble metallocorroles a series of 10-aryl-5,15-pyridinium manganese(III) corroles was prepared. These complexes were examined regarding the effect of the C(10) substituent on the Mn(IV)/Mn(III) redox potentials, catalytic rate constants for decomposition of HOONO, prevention of tyrosine nitration, and superoxide dismutase activity. This structure-activity relationship investigation provides new insight regarding the mechanism by which manganese(III) corroles act as catalytic antioxidants. It also discloses the superiority of the C(10)-anysil-substituted complex in all examined aspects.     

Relation between energy and mass in Bohr's essay on his debate with einstein

The famous debate between Einstein and Bohr on the (in)consistency of quantum mechanics was described in detail by Bohr in his essay of 1949. The present article comments not on the main subject of the debate but only on the terminology that is relevant to the notions of the theory of relativity and which was used by the participants. In particular, their statement on the equivalence of mass and energy should not be taken literally. In fact, the rest energy is meant here. The authority of the two great physicists should not be misused to preserve the confusing terminology.     

On the electroweak and gluonic corrections to the hadronic width of the Z boson

The electroweak corrections to the Z-boson hadronic width are presented in a simple analytical form for the width itself, Λ_h, for its ratio to the leptonic width, R_l = Λ_h/Λ_l, for the Λ_b/Λ_h ratio, and for the total width Λ_Z. The rational parametrization, advocated in our recent papers on leptonic decays, simplifies the analysis of the hadronic decays too. There are two main results of this analysis: (1) All electroweak precision measurements agree within 1 σ with the electroweak Born approximation if the gluon coupling constant . Thus the electroweak radiative corrections have not been observed experimentally. The unexpected smallness of electroweak radiative corrections is caused by the mutual cancellation of the large positive contribution of a heavy top quark and the large negative contribution of all other virtual particles. (2) With electroweak radiative corrections being taken into account, the value of extracted from the experimental value of Λ_Z differs by 3σ from that obtained from R_l, if m_t 200 GeV; they agree within 1σ if m_t 150 GeV. Thus a low upper limit on m_t can be obtained from hadronic decays of the Z-boson alone, even without data on its leptonic decays.