Steering in computational science: Mesoscale modelling and simulation

This paper outlines the benefits of computational steering for high performance computing applications. Lattice-Boltzmann mesoscale fluid simulations of binary and ternary amphiphilic fluids in two and three dimensions are used to illustrate the substantial improvements which computational steering offers in terms of resource efficiency and time to discover new physics. We discuss details of our current steering implementations and describe their future outlook with the advent of computational grids.     

Isolobal analogy between trivalent boron and divalent silicon

Singlet organosilylenes with a lone pair and an emptyp orbital are isolobal to trivalent borane if a B-H is equated to the lone pair on Si. Using this analogy, a particular isomer of CSi₂H₂ (24) is predicted to be a stable structure. MNDO calculations on24 and many of its possible isomers suggest that24 is at global minimum on the potential energy surface of CSi₂H₂.Ab initio calculations using a, minimal STO-3G basis set, on some selected structures also support these results.     

On the decrease in the ring π-current upon η6-coordination with a transition metal atom

A synthesis of [10]paracyclophane (Pc) and its organometallic complexes, Pc·Cr(CO)₃, [PcMn(CO)₃]⁺BF₄ ^–, (PcRuC₅Me₅)⁺·PF₆ ^–, (PcRhC₅Me₅)²⁺(BF₄ ^–)₂, and PcCo₄(CO)₉ has been carried out. The¹H NMR spectra of mononuclear complexes of neutral Cr and monocationic derivatives of Mn and Ru have been examined. ⁶-Coordination with a transition metal atom causes a decrease in the ring -current which is exhibited as a downfield displacement of the resonance signals from the protons of the --CH₂ groups in relation to those of free Pc. In the monocationic complexes the deshielding action of the positive charge is also added to this effect. In the¹H NMR spectrum of the cluster PcCo₄(CO)₉ the resonance signals from the --CH₂ protons are shifted upfield in relation to the Pc signals. Consequently, the concept of the ring -current decrease needs more detailed investigation for cluster systems.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1467–1470, August, 1993.     

Synthesis and complexing properties of phosphoryl-substituted salicylaldimines

Starting from meta and ortho isomers of (diphenylphosphorylmethyl)anilines 2a,b, procedures were developed for the synthesis of new phosphoryl-substituted Schiff bases 3a,b serving as tridentate ligands. In alcoholic solutions, ligands 3a,b form complexes of different composition with praseodymium and neodymium nitrates. Only the M(L)₂(NO₃)₃ complexes crystallized from solution regardless of the reactant ratio. According to the X-ray diffraction study and IR spectroscopy, one of the ligands in the complexes with ortho ligand 3b is coordinated in a bidentate fashion via the oxygen atom of the P=O group and the phenoxy oxygen atom, whereas the second ligand molecule forms a coordination bond with metal only via the phosphoryl oxygen atom. In the Pr(3a)₂(NO₃)₃ complexes, both meta ligands 3a are involved in thebidentate O,O-coordination. Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1827–1835, September, 2007.     

Interaction of 2-methyl-2,5-dioxo-1,2-oxaphospholane with trimethylsilyl cyanide

The reaction of 2-methyl-2,5-dioxo-1,2-oxaphospholane (1) with trimethylsilyl cyanide was found to give, depending on conditions, three organophosphorus compounds: trimethylsilyl methyl(2-cyanocarbonylethyl)phosphinate (2), trimethylsilyl methyl(3-trimethylsiloxy-3,3-dicyanopropyl)phosphinate (3) and trimethylsilyl methyl(3-trimethyl-siloxy-3-cyano-2-propenyl)phosphinate (4), On hydrolysis of3 under mild conditions, methyl(3-hydroxy-3,3 dicarboxypropyl)phosphinic acid (7) was obtained. The latter is readily decarboxylated on heating to give methyl(3-hydroxy-3-carboxy-propyl)phosphinic acid (8). The interaction of2 and4 with water or alcohols gives, correspondingly, methyl[2-carboxy(alkoxycarbonyl) ethyl]phosphinic acids (11–13). Methyl(2-oxamoyiethyl)phosphinic acid (14) was prepared by successive treatment of propenylphosphinate4 with HCl gas and water.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 170–177, January, 1993.     

The Selective C-Mono-and C,C-Dialkylation of Thiophosphorylacetonitriles and Reactivity of the Products

The facile synthetic route to selective C-mono-and C,C-dialkylation of thiophosphorylacetonitriles by primary haloalkanes under phase transfer catalysis conditions has been developed. Using under the same conditions unsymmetric α,ω-dihaloalkanes results in different linear and cyclic products depending on the alkylene chain length. 3-Halopropylsubstituted thiophosphorylacetonitriles synthesized transform to mono-and bis-heterophosphacyclanes under elevated temperatures.     

Measurement of the ground state 2n pickup probability for 28Si+68Zn and its role in sub-barrier fusion enhancement

The ground state and excited state transfer yields for the 2-neutron pickup channel in the ²⁸Si+⁶⁸Zn system have been measured explicitly. The recoil mass separator at the nuclear Science Centre, New Delhi was used for the measurement. A NaI(T1) detector was used for detecting the deexcitation γ’s from the transfer products. The kinematic coincidence technique was employed for the transfer measurement. Simplified coupled channels calculations show that out of all transfer channels the major contribution to the sub-barrier enhancement comes from the ground state 2 neutron pickup channel with a ground state Q-value of+1.83 MeV.     

Free Convective Nonaligned Non-Newtonian Flow with Non-linear Thermal Radiation

The present study explores the free convective oblique Casson fluid over a stretching surface with non-linear thermal radiation effects. The governing physical problem is modelled and transformed into a set of coupled non-linear ordinary differential equations by suitable similarity transformation, which are solved numerically with the help of shooting method keeping the convergence control of 10^-5 in computations. Influence of pertinent physical parameters on normal, tangential velocity profiles and temperature are expressed through graphs. Physical quantities of interest such as skin friction coefficients and local heat flux are investigated numerically.     

Effect of processing temperature during spin-on application on the properties of sol-gel silica films

The effect of the temperature (of the substrate and the solution) during film deposition on spin coating process of sol-gel films is discussed. The increase of substrate temperature as well as coating solution liquid temperature leads to formation of thicker films with higher porosity. The temperature dependence of films thickness is mainly determined by the change of solvent vapour pressure with consideration for the change of liquid viscosity.