The properties of the miniature silicon photodiodes in a 14.7 MeV neutron field

The properties of miniature therapeutic silicon photodiodes in a 14.7 MeV field are outlined in the paper. The responses of the photodiode to the tissue dose rate of both the photons and 14.7 MeV neutrons are given. The decrease in sensitivity due to radiation damage is specified for a n- field.     

Theoretical and experimental studies on solubility and reactivity behavior of lysergol,elymoclavine, and dihydrolysergol

Lysergol, elymoclavine (Δ^9,10 and Δ^8,9 regioisomers), and dihydrolysergol are important members of ergolines. The present work reports their comparative study in gas and solvent phase (water) that has been performed both experimentally and theoretically. Theortical calculations have been carried within the density functional theory formalism to analyze the structural and electronic properties of these molecules with B3LYP hybrid exchange–correlational fuctional in conjunction with 6‐311++G (d,p) basis set. Hessian calculations are performed at B3LYP/6‐31G (d,p) level of theory in gas phase as well as other solvent phases. Solvent phase calculations are performed using Onsager reaction field model as implemented in Gaussian 03. A good agreement has been found between experimental and theoretical infrared and nuclear magnetic resonance (NMR) spectra. The calculated NMR data has been analyzed statistically. Stability of these regioisomers has been analyzed in terms of the energy gap between highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO–LUMO gap). Calculations for lysergol and elymoclavine in water as solvent were carried to examine the effect of solvent on the HOMO–LUMO levels and energy of these molecules. © 2012 Wiley Periodicals, Inc.     

Temperature- and pressure-dependent kinetico-mechanistic studies on the formation of mixed-valence {(tetraamine)CoIIINCFeII(CN)5}− units

The reduction of Co^III in the tetraamine-encapsulating ligand complex [Co^III{(μ-ET)(Me₂)cyclen}(H₂O)₂]³⁺ by [Fe^II(CN)₆]^4? has been studied kinetico-mechanistically at different pH, temperatures, and pressures. The process agrees with the expected outer-sphere redox mechanism, with the value of the encounter-complex equilibrium constant large enough to allow for kinetic determination of the first-order electron transfer reaction rate constant. The value of the encounter-complex equilibrium constant, K_pre-eq, is not only dependent on the charge of the redox partners, but also on the establishment of an important network of hydrogen bonds. These can also explain the differences obtained in the activation volumes determined for the diaqua and bis-hydroxo complexes. Neither the leaching of Co^II nor the presence of [Fe^III(CN)₆]^3? is observed in the final reaction medium, which indicates that a fast sequence involving substitution on the transient Co^II complex followed by a fast inner-sphere electron transfer takes place. This sort of mechanism has already been established for encapsulating pentaamine ligand complexes, but this is the first example of such a sequential reaction occurring on a tetradentate ligand complex. Preliminary UV–Vis and electrochemical characterization experiments have been conducted on the final reaction mixtures, suggesting the formation of a stable cyanide-bridged Co^III/Fe^II mixed-valence complex of the same type reported in the literature for encapsulating {Co^III(N)₅} skeletons.     

Invariant Gaussian processes and independent sets on regular graphs of large girth

We prove that every 3‐regular, n‐vertex simple graph with sufficiently large girth contains an independent set of size at least 0.4361n. (The best known bound is 0.4352n.) In fact, computer simulation suggests that the bound our method provides is about 0.438n. Our method uses invariant Gaussian processes on the d‐regular tree that satisfy the eigenvector equation at each vertex for a certain eigenvalue . We show that such processes can be approximated by i.i.d. factors provided that . We then use these approximations for to produce factor of i.i.d. independent sets on regular trees. © 2014 Wiley Periodicals, Inc. Random Struct. Alg., 47, 284–303, 2015     

Über die Kinetik der durch Schwefelsäure katalysierten Reaktion von Chloral und Benzol

The kinetical parameters of 1-phenyl-1-hydroxy-2,2,2-trichloro-ethane and 1,1-diphenyl-2,2,2-trichloro-ethane production and the simultaneous sulphonation reaction were determined, taking into account the alteration of the reaction rate constants caused by the dilution of the sulphuric acid catalyst.

     

Brownian beads

We show that the past and future of half-plane Brownian motion at certain cutpoints are independent of each other after a conformal transformation. Like in Itôs excursion theory, the pieces between cutpoints form a Poisson process with respect to a local time. The size of the path as a function of this local time is a stable subordinator whose index is given by the exponent of the probability that a stretch of the path has no cutpoint. The index is computed and equals 1/2.Research partially supported by NSF grant #DMS-0206781. Mathematics Subject Classification (2000):60J65; 30C35