The electrolytic efficiency of amperometric detection in normal-phase high-performance liquid chromatography

The electrolytic efficiency of the wall-jet detector in normal-phase high-performance liquid chromatography (between 0.1 and 5%) is significantly less than its efficiency in reversed-phase separations. A large-volume wall-jet cel with a Ag/Ag⁺ reference serves as the detector system in evaluating the effects of various chromatographic conditions on efficiency. Anthraquinone, phenanthrenaquinone (both at 10^-3–10^-4 M) and three estrogen gen steroids (at 10^-2–10^-3 M) are used as samples with ethanol/ hexane eluents. The effect of pH depends on the sample; increased ethanol concentrations and lower flow rates improve the efficiency.     

Rational design of platinum(IV) compounds to overcome glutathione-S-transferase mediated drug resistance

A rationally designed Pt(IV) anticancer compound is described, employing the novel concept of tethering an inhibitor of glutathione-S-transferase, an enzyme associated with Pt-based drug-resistance, to cisplatin. Its enzyme inhibition activity, investigated using spectrophotometric and mass spectrometry-based techniques, and cytotoxic profile in resistant cancer cells are described.     

Symmetric Weighing Matrices Constructed using Group Matrices

A weighing matrix of order n and weight m² is a square matrix M of order n with entries from {-1,0,+1} such that MM^T=m²I where I is the identity matrix of order n. If M is a group matrix constructed using a group of order n, M is called a group weighing matrix. Recently, group weighing matrices were studied intensively, especially when the groups are cyclic and abelian. In this paper, we study the abelian group weighing matrices that are symmetric, i.e.M^T=M. Some new examples are found. Also we obtain a few exponent bounds on abelian groups that admit symmetric group weighing matrices. In particular, we prove that there is no symmetric abelian group weighing matrices of order 2p^r and weight p² where p is a prime and p≥ 5.Communicated by: K.T. Arasu     

Microwaves make hydroformylation a rapid and easy process

[reaction: see text] Hydroformylation of alkenes can be carried out in a few minutes under microwave activation at a relatively low pressure (40 psi) using commercially available catalysts and ligands. The 80 mL vial of a Discover microwave oven was connected to a cylinder of CO and H2, and after filling the reactor at 40 psi, a mixture of an alkene, the Wilkinson catalyst, and XANTPHOS was submitted to microwave irradiation giving, after 4 min, high conversion into the corresponding aldehyde without formation of the isomerized alkene.     

Eta1 and eta2 complexes of lambda3-1,2,4,6-thiatriazinyls with CpCr(CO)x

The title heterocyclic radicals coordinate to either 17e CpCr(CO)3 or 15e CpCr(CO)2 moieties as one-electron or as three-electron donors, respectively; in the former the bonding is via the perpendicular p orbital of the sulfur atom, while in the latter bonding is via p(pi) orbitals on both sulfur and nitrogen.     

A nonclassical LIL for geometrically weighted series in Banach space

Let {X, Xn ; n ≥ 0} be a sequence of independent and identically distributed random variables, taking values in a separable Banach space (B,||·||) with topological dual B* . Considering the geometrically weighted series ξ(β) =∑∞n=0βnXn for 0 β 1, and a sequence of positive constants {h(n), n ≥ 1}, which is monotonically approaching infinity and not asymptotically equivalent to log log n, a limit result for(1-β2)1/2||ξ(β)||/(2h(1/(1-β2)))1/2 is achieved.     

Special Green’s function boundary element approach for steady-state axisymmetric heat conduction across low and high conducting planar interfaces

The problem of determining the steady-state axisymmetric temperature distribution in a bimaterial with a planar interface is considered here. The interface is either low or high conducting. Special Green’s functions satisfying the thermal conditions on the interface are derived and employed to obtain boundary integral equations whose path of integration does not include the interface. Boundary element procedures that do not require the interface to be discretized into elements are proposed for solving the problem under consideration.