Investigation of the Parameters of Muon-Catalyzed Fusion in Double D/T Mixture at High Temperature and Density

Experiments on the study of the muon catalyzed fusion (μCF) process in a double D/T mixture of hydrogen isotopes in the temperature range 300–800 K at densities 0.3–0.5 LHD are performed at the JINR phasotron. The values of the effective μCF parameters (cycling rate λ _c , neutron yield Y _n , muon losses w) are obtained. Tentative dtμ-molecule formation rates on D₂ and DT molecules (λ _dtμ−d and λ _dtμ−t ) are obtained for different mixture temperatures and densities. The results obtained show that λ _dtμ−t increases with temperature, but its value is smaller than theoretical predictions. This revised version was published online in August 2006 with corrections to the Cover Date.     

High precision quantum control of single donor spins in silicon

The Stark shift of the hyperfine coupling constant is investigated for a P donor in Si far below the ionization regime in the presence of interfaces using tight-binding and band minima basis approaches and compared to the recent precision measurements. In contrast with previous effective mass-based results, the quadratic Stark coefficient obtained from both theories agrees closely with the experiments. It is also shown that there is a significant linear Stark effect for an impurity near the interface, whereas, far from the interface, the quadratic Stark effect dominates. This work represents the most sensitive and precise comparison between theory and experiment for single donor spin control. Such precise control of single donor spin states is required particularly in quantum computing applications of single donor electronics, which forms the driving motivation of this work.     

Electric Field Induced Changes of Spin Lattice Relaxation Time T1 in Polar Liquids

T ₁ was found to change linearly with applied electric field for the liquids nitrobenzene, chlorobenzene, ether and dioxane: no change was observed in hexane and cyclohexane. These substantial reductions in T ₁ are explained in terms of quasi-crystalline structures in the liquid.     

Study of burning behavior of small scale wood crib with cone calorimeter

Burning behavior of small-scale wood crib was studied by a serial of cone calorimeter tests. The heat release rate curves of these small wood cribs were different due to porosity factor and this shows that the control condition switches from one to another. The burning of some crib with small porosity factors was self-extinguished in fixed flow rate of air supply in cone calorimeter. These results were compared with Gross’s studies. The switch point of porosity-controlled and surface area controlled burning regime is different from Gross’s result.     

Design,synthesis, antitubercular and antibacterial activities of pyrrolo[3,2-b]pyridine-3-carboxamide linked 2-methoxypyridine derivatives and in silico docking studies

Abstract

A novel series pyrrolo[3,2-b]pyridine-3-carboxamide linked 2-methoxypyridine derivatives have been designed, synthesized and confirmed by FT-IR, ¹H NMR, ¹³C NMR, ¹⁹F NMR, MS, and elemental analysis. The synthesized compounds were screened for their antitubercular activity using microplate alamar blue assay method and antibacterial activity. Among the tested compounds, 4- fluorophenyl (8m), 4- chlorophenyl (8n) and 4-methoxyphenyl (8i) showed potent anti-TB activity (3.12?µg/mL) in comparison with reference drug, Pyrazinamide ((3.12?µg/mL). In addition, all compounds were docked into DprE1 (PDB code: 4KW5) to explore their binding interactions at the active site. The compounds exhibited essential key interactions as that of reported DprE1 inhibitors and hence, the synthesized compounds may be considered as molecular scaffolds for antitubercular activity. Compounds, 4-chlorophenyl (8n) and 4-flurophenyl (8m) showed significant antibacterial activity against Escherichia coli and Staphylococcus aureus strains. In silico prediction of toxicities, druglikeness and drug score profiles of the tested compounds are promising.     

Use of Knowledge Bases and QSARS to Estimate the Relative Ecological Risk of Agrichemicals: A Problem Formulation Exercise

Abstract

Ecological risk assessments can be used to establish the likelihood that an adverse effect will result from exposure to one or more chemicals. When evaluating contaminated sites with many chemicals present, risk assessors must grapple with the problem of quickly identifying the chemicals that are most likely to be of concern, based on effect and exposure assessment information. Many times data gaps exist and the risk assessor is left with decisions on which models to use to estimate the parameter of concern. In the present paper, a procedure is presented for ranking agrichemicals, utilizing the ASTER (ASsessment Tools for the Evaluation of Risk) system. The procedure was employed to rank the relative ecological risk of forty-nine pesticides historically used in agricultural sites in the Walnut Creek watershed near Ames, Iowa, USA. Empirical data from the ASTER system were used when available in the associated data-bases, and quantitative structure-activity relationships and expert systems were invoked when data were lacking. Separate rankings were conducted based on major species taxonomic groupings. Resulting toxic effects thresholds were compared to surface water concentrations.     

SAR Models for Futile Metabolism: One-Electron Reduction of Quinones,Phenols and Nitrobenzenes

Abstract

Benzoquinones, naphthoquinones and aziridinylbenzoquinones, can be reduced by flavoproteins to semiquinones that react with molecular oxygen to form superoxide anion with the subsequent regeneration of the parent compounds. This redox cycling, a form of futile metabolism, produces reactive oxygen species and depletes the reducing equivalents of cells without concomitant energy production. The ability of a toxicant to redox cycle is related to its one-electron reduction potential, and this study attempted to estimate reduction potential from structure using semi-empirical quantum chemical models for a diverse set of chemicals. The results of this study suggest that one-electron reduction potentials, within structural classes of benzoquinones, naphthoquinones, phenols and nitrobenzenes, can be estimated from local and global electronic indices that are related to delocalization. Smaller absolute charge on the carbonyl carbon in the quinone moiety correlated with more positive one-electron reduction potentials of 1,4-benzoquinones, naphthoquinones and two-electron reduction potentials of aziridinylbenzoquinones. The energy of frontier orbitals of the quinones, phenols and nitrobenzenes also co-varied with reduction potential. More positive reduction potentials of 1,4-benzoquinones, 1,4-naphthoquinones and phenols were correlated with more negative values of E_HOMO, while more negative values of E_LUMO were correlated with more positive potentials of nitrobenzenes and aziridinylbenzoquinones. Delocalization of electron density also correlated with reduction potentials within individual classes.     

Efficient clocked electron transfer on superfluid helium

Unprecedented transport efficiency is demonstrated for electrons on the surface of micron-scale superfluid helium-filled channels by co-opting silicon processing technology to construct the equivalent of a charge-coupled device. Strong fringing fields lead to undetectably rare transfer failures after over a billion cycles in two dimensions. This extremely efficient transport is measured in 120 channels simultaneously with packets of up to 20 electrons, and down to singly occupied pixels. These results point the way towards the large scale transport of either computational qubits or electron spin qubits used for communications in a hybrid qubit system.