Electrochemical detection of modified maize gene sequences by multiplexed labeling with osmium tetroxide bipyridine

In this report we demonstrate an approach for the electrochemical detection of four sequences from maize and genetically modified (GM) maize by means of square-wave voltammetry (SWV). After multiplexed labeling with osmium tetroxide bipyridine ([OsO₄(bipy)]), the target oligonucleotides are hybridized with a complementary DNA capture probe immobilized on gold electrodes. The multiplexed labeling was performed by mixing the four target strands with the respective oligonucleotides 80% homologous to the central target recognition sequences in order to protect the latter from binding of [OsO₄(bipy)] to its thymine or cytosine residues. All components were added to the same solution. No significant decreases in SWV hybridization signals were observed after such multiplexed labeling of up to four target strands in the same reaction batch. Obtained voltammetric signals were significantly higher at 50 °C compared to 25 °C hybridization temperature and very low response was observed for non-complementary strands. Multiplexed labeling with osmium tetroxide bipyridine holds great promise for the development of simple and effective voltammetric detection protocols for GM organisms.     

On the use of corresponding orbitals for the construction of mutually orthogonal orbital sets

Consider two orbital sets χ_k, k = 1…m and η₁, 1 = 1…n, which are mutually nonorthogonal. Provided that n > m, at least n ? m orbitals of the set {η} can be orthogonalized to the set {χ} by a transformation within the set {η}. The orthogonalization of the remaining orbitals of {η} to the set {χ} requires a transformation in which the χk appear explicitly. The orthogonalization of one orbital set to another is relevant for SCF optimizations in a truncated basis set, in the presence of frozen occupied orbitals. Examples are frozen core calculations, ECP calculations, and embedded cluster calculations, where the cluster is embedded in a frozen environment. A simple orthogonalization scheme, which makes use of a corresponding orbital transformation, is presented. It is suggested that with a small, well-defined extension of the set {η} the complete orthogonalization can be done with a transformation in which the {χ} do not appear explicitly. © 1993 John Wiley & Sons, Inc.     

On the hamiltonian theory of surface waves

It is shown that the classical theory of gravity driven waves on the surface of a non-viscous liquid can be derived from a set of canonical equations. Various approximate equations then can be found by introducing suitable approximations to the kinetic and potential energy functionals. The stability of these approximate equations then can be insured beforehand by using positive definite approximate energy functionals. For fairly long, fairly low waves a stable equation of Boussinesq type is derived in this way. This equation is also valid for waves which are not approximately simple.