The Suzuki Reaction Under Solvent-Free Conditions

The coupling reaction of diverse arylhalogenids with phenyl-boronic acid under solvent-free conditions has been performed using a palladium catalyst. The order of reactivity was complementary to the normal Suzuki reaction.     

The nucleophilic ring-opening of N-benzylquinuclidinium bromide

N-Benzylquinuclidinium bromide was ring opened by a series of heteronucleophiles, in the presence of cesium carbonate, to yield the corresponding N-benzyl-4-(2-hetero-ethyl)piperidines. The best yields were found with thiophenol (56%), phenol (55%), and benzimidazole (38%) as nucleophiles.     

Single-step link of the superdeformed band in143Eu

²⁰⁹Fr has been produced by irradiation of¹⁹⁷Au with¹⁶O,and studied using a He-jet recoil tape transport system.A decay scheme is proposed for the first time,based on X-γ and γ-γ coincidence measurements,which takes account of 20 observed γ-rays. The branching ratio for (EC+β ⁺) decay of²⁰⁹Fr has been estimated to be 3.0±1.5%. Five members of low-lying states in²⁰⁹Rn can be explained with the configuration [(²¹⁰Rn 2⁺)(νf5/2)^?1].     

On some versions of incomplete block-matrix factorization iterative methods

Various forms of preconditioning matrices for iterative acceleration methods are discussed. The preconditioning is based on two versions of incomplete block-matrix factorization.     

High-order methods for parabolic problems

Error estimates valid for all t ? 0 for the semi-discrete Galerkin approximation of a parabolic mixed boundary-initial value problem are presented. The solution of the resulting system of ordinary differential equations by implicit Runge-Kutta formulae for arbitrarily high order of accuracy, are discussed. Strongly A-stable methods are found to be advantageous. Theoretical and experimental results for the solution of the resulting system of algebraic equations using a preconditioned outer iteration scheme are discussed. Even the inner linear algebraic equations are preferably solved by iteration.     

SPE and HPLC/UV of resin acids in colophonium-containing products

A new method, involving SPE and HPLC/UV diode-array detection (DAD), was developed for the quantification of colophonium components in different consumer products, such as cosmetics. Colophonium is a common cause of contact dermatitis since its components can oxidize into allergens on exposure to air. Three different resin acids were used as markers for native and oxidized colophonium, abietic acid (AbA), dehydroabietic acid (DeA), and 7-oxodehydroabietic acid (7-O-DeA). The SPE method, utilizing a mixed-mode hydrophobic and anion exchange retention mechanism, was shown to yield very clean extracts. The use of a urea-embedded C(12) HPLC stationary phase improved the separation of the resin acids compared to common C(18). Concentrations higher than 2 mg/g of both AbA and DeA were detected in wax strips. In this product also 7-O-DeA, a marker for oxidized colophonium, was detected at a level of 28 microg/g. The LODs were in the range of 7-19 microg/g and the LOQs 22-56 microg/g. The method is simple to use and can be applied on many types of technical products, not only cosmetics. For the first time, a method for technical products was developed, which separates AbA from pimaric acid.     

Comparison of preconditioned Krylov subspace iteration methods for PDE-constrained optimization problems

We construct a novel multi-step iterative method for solving systems of nonlinear equations by introducing a parameter θ to generalize the multi-step Newton method while keeping its order of convergence and computational cost. By an appropriate selection of θ, the new method can both have faster convergence and have larger radius of convergence. The new iterative method only requires one Jacobian inversion per iteration, and therefore, can be efficiently implemented using Krylov subspace methods. The new method can be used to solve nonlinear systems of partial differential equations, such as complex generalized Zakharov systems of partial differential equations, by transforming them into systems of nonlinear equations by discretizing approaches in both spatial and temporal independent variables such as, for instance, the Chebyshev pseudo-spectral discretizing method. Quite extensive tests show that the new method can have significantly faster convergence and significantly larger radius of convergence than the multi-step Newton method.     

Direct immobilization of cholesteryl-TEG-modified oligonucleotides onto hydrophobic SU-8 surfaces

We introduce a rapid, simple one-step procedure for the high-yield immobilization of cholesteryl-tetraethyleneglycol-modified oligonucleotides (chol-DNA) at hydrophobic sites made of SU-8 photoresist. Topographic structures of SU-8 were microfabricated on microscope glass coverslips sputtered with a Ti/Au layer. Upon application, chol-DNA adsorbed to the SU-8 structures from solution, leaving the surrounding gold surface free of chol-DNA. chol-DNA immobilization is complete within 15 min and yields a surface coverage in the range of 20-95 pmol/cm(2), which corresponds to a film density of 10(12)-10(13) molecules/cm(2). chol-DNA immobilization is stable and can be sustained despite rinsing, drying, dry storage for several hours, and rehydration of chips. Furthermore, complementary DNA in solution hybridizes efficiently to immobilized chol-DNA.