HMPA-Mediated conjugate addition of alkyl- and phenylthioallyl anions to cyclopentenone

One equivalent of HMPA induces 1,4-addition of the title anions predominantly through the $\text{α}$-position to cyclopentenone in THF at ?78°. In THF alone irreversible addition takes place to give mixtures comprising largely $\text{α}$ and $\text{γ}$-1,2 products.     

A study of the reactions γp→ωp and γp→ωp and γp→ωΔ+

The differential and total corss sections and the decay density matrix elements have been measured for the reactions, γp→ωp and γp→ωΔ⁺ (1232) in the photon energy range 2.8 to 4.8 GeV. The total cross sections for ωΔ⁺ (1232) photo-production are found to be slightly larger than those for elastic ω photo-production in this energy range. The data are compared to the predictions of a theoretical model and the contributing exchange mechanics are discussed.     

Linewidth measurements of the ν2 + ν4 R(29) absorption in CF4

Linewidth measurements of the ν₂ + ν₄ R⁺(29) A₁⁴ + E⁹ + F₁¹⁴ absorption at 1073.279 cm⁻¹ were made in the pressure range of 0.5 to 50 Torr CF₄. The data, after correction for Doppler broadening, reduce to a self-broadening coefficient of 10.8 ± 0.4 MHz/Torr. Comparisons of the linewidth for pure CF₄ with the linewidth of an Ar-CF₄ mixture and with the prediction of the hard-sphere, gas-kinetic model imply a relaxation mechanism that is not dominated by a resonant (V-V) process, and has an effective cross section that is intermediate in size between the cross sections associated with dipole-dipole and hard-sphere collisions.     

Investigation into the molecular structure and energetic stability of endohedral and exohedral metallofullerene derivatives of C24

Density-functional theory was applied to the investigation of the structural and electronic properties of C₂₄ fullerene derivatives. Transition metals (TMs) from groups 11 and 12, in various oxidation and spin-states, are inserted at either endohedral (TM@C₂₄) or exohedral (TM-C₂₄) sites and their subsequent energetic stabilities are assessed. With the exception of Ag@C₂₄, all derivatives are predicted to occupy a minimum on the potential energy surface. The optimized exohedral TM-C₂₄ geometries yield TM-C bond lengths that are consistent with comparable carbon-metal bond lengths, and the overwhelming majority of the derivatives result in a slight deformation of the C₂₄ cage as the bonding carbon takes on more sp³ character. All of the TM@C₂₄ equilibrium structures maintain the integrity of the cage structure with a moderate increase in the diameter. All neutral exohedral and endohedral complexes favor the low spin-state; conversely, all of the charged exohedral complexes prefer the high spin-state, with the exception of Cu-C₂₄¹⁺ molecular ion. The Group 12 charged endohedral derivatives prefer the low spin-state, whereas the Group 11 molecular ions do not necessarily exhibit a definitive trend. Analysis of the energetic data predicts that of the lowest energy endohedral molecular species only four are predicted to be energetically favorable in terms of insertion energy and an advantageous HOMO-LUMO gap: Cu@C₂₄²⁺, Ag@C₂₄¹⁺, Au@C₂₄³⁺, and Zn@C₂₄²⁺.     

The Role of Atomic Oxygen and Ozone in the Plasma and Post-plasma Catalytic Removal of N2O

Plasma Chemistry and Plasma Processing - The destruction of nitrous oxide in oxygen using plasma and post-plasma catalytic treatments was investigated experimentally in atmospheric-pressure...     

Rapid detection of a foreign protein in milk using IMS–SERS

A method for rapid detection of foreign protein contamination in complex food matrices is critically needed. Here we present a novel method that combines immunomagnetic separation (IMS) and surface‐enhanced Raman scattering (SERS) to detect ovalbumin (OVA), an egg white protein, added into whole milk. IMS was used to specifically capture the OVA out of the milk. Then SERS was applied to analyze the IMS eluate using silver dendrites as the substrate. Two SERS sample preparation methods, namely solution based and substrate based, were used to prepare the IMS eluate for SERS analysis. Results show both methods were able to detect 1 µg OVA in 1 ml milk (1 part per million). Based on the results of principal component analysis and partial least‐squares analysis, solution SERS was more capable of quantitative analysis, while substrate SERS was more sensitive for qualitative analysis. The total analytical time for IMS–SERS was less than 20 min, which satisfied the requirement of rapid detection in a milk processing facility. Copyright © 2011 John Wiley & Sons, Ltd.     

Elucidation of the Streptomyces coelicolor pathway to 2-undecylpyrrole, a key intermediate in undecylprodiginine and streptorubin B biosynthesis

The red gene cluster of Streptomyces coelicolor directs production of undecylprodiginine. Here we report that this gene cluster also directs production of streptorubin B and show that 2-undecylpyrrole (UP) is an intermediate in the biosynthesis of undecylprodiginine and streptorubin B. The redPQRKL genes are involved in UP biosynthesis. RedL and RedK are proposed to generate UP from dodecanoic acid or a derivative. A redK(-) mutant produces a hydroxylated undecylprodiginine derivative, whereas redL(-) and redK(-) mutants require addition of chemically synthesized UP for production of undecylprodiginine and streptorubin B. Fatty acid biosynthetic enzymes can provide dodecanoic acid, but efficient and selective prodiginine biosynthesis requires RedPQR. Deletion of redP, redQ, or redR leads to an 80%-95% decrease in production of undecylprodiginine and an array of prodiginine analogs with varying alkyl chains. In a redR(-) mutant, the ratio of these can be altered in a logical manner by feeding various fatty acids.     

Partitioning the Vertices of a Graph into Two Total Dominating Sets

A total dominating set in a graph G is a set S of vertices of G such that every vertex in G is adjacent to a vertex of S. We study graphs whose vertex set can be partitioned into two total dominating sets. In particular, we develop several sufficient conditions for a graph to have a vertex partition into two total dominating sets. We also show that with the exception of the cycle on five vertices, every selfcomplementary graph with minimum degree at least two has such a partition.     

Vertex-edge domination in graphs

In this paper we study graph parameters related to vertex-edge domination, where a vertex dominates the edges incident to it as well as the edges adjacent to these incident edges. First, we present new relationships relating the ve-domination to some other domination parameters, answering in the affirmative four open questions posed in the 2007 PhD thesis by Lewis. Then we provide an upper bound for the independent ve-domination number in terms of the ve-domination number for every nontrivial connected K_1,k-free graph, with k ≥ 3, and we show that the independent ve-domination number is bounded above by the domination number for every nontrivial tree. Finally, we establish an upper bound on the ve-domination number for connected C₅-free graphs, improving a recent bound given for trees.