A biotinylated intercalator for selective post-labeling of double-stranded DNA as a basis for high-sensitive DNA assays

For increasing the sensitivity of label-free DNA assays an amplification strategy is proposed based on the synthesis of a proflavine derivative which on the one hand retains its high affinity for double-stranded DNA (dsDNA) intercalation and on the other hand is functionalized via a flexible spacer with biotin moieties. By this, subsequent to the post-labeling of areas with dsDNA, reporter systems such as streptavidin/enzyme conjugates can be bound. Amplified DNA hybridization detection using an oligonucleotide model system, a biotinylated proflavine as intercalator and streptavidin/alkaline phosphatase is demonstrated.     

Multidimensional scaling and visualization of large molecular similarity tables

Multidimensional scaling (MDS) is a collection of statistical techniques that attempt to embed a set of patterns described by means of a dissimilarity matrix into a low‐dimensional display plane in a way that preserves their original pairwise interrelationships as closely as possible. Unfortunately, current MDS algorithms are notoriously slow, and their use is limited to small data sets. In this article, we present a family of algorithms that combine nonlinear mapping techniques with neural networks, and make possible the scaling of very large data sets that are intractable with conventional methodologies. The method employs a nonlinear mapping algorithm to project a small random sample, and then “learns” the underlying transform using one or more multilayer perceptrons. The distinct advantage of this approach is that it captures the nonlinear mapping relationship in an explicit function, and allows the scaling of additional patterns as they become available, without the need to reconstruct the entire map. A novel encoding scheme is described, allowing this methodology to be used with a wide variety of input data representations and similarity functions. The potential of the algorithm is illustrated in the analysis of two combinatorial libraries and an ensemble of molecular conformations. The method is particularly useful for extracting low‐dimensional Cartesian coordinate vectors from large binary spaces, such as those encountered in the analysis of large chemical data sets. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 488–500, 2001     

Proton-Conducting Composites Based on the Cs<Subscript>4</Subscript>(HSO<Subscript>4</Subscript>)<Subscript>3</Subscript>(H<Subscript>2</Subscript>PO<Subscript>4</Subscript>) Compound

Proton-conducting composites xCs₄(HSO₄)₃(H₂PO₄) + (1–x)AlPO₄ in the composition range x = 0.9–0.5 have been obtained. Their transport properties are studied by impedance spectroscopy. The dependences of the phase composition of the materials on the component ratio are investigated by X-ray diffraction analysis. The spatial phase distribution in the materials is analyzed using scanning electron microscopy.     

On the Existence of Pure,Broadband Toroidal Sources in Electrodynamics

Multipoles are paramount for describing electromagnetic fields in many areas of nanoscale optics, playing an essential role in the design of devices in plasmonics and all-dielectric nanophotonics. Challenging the traditional division into electric and magnetic moments, toroidal moments are proposed as a physically distinct family of multipoles with significant contributions to the properties of matter. However, the apparent impossibility of separately measuring their response sheds doubt on their true physical significance. Here, the possibility of selectively exciting toroidal moments is confirmed without any other multipole. A set of general conditions is developed that any current distribution must fulfill to be entirely described by toroidal moments and prove the results in an analytically solvable case. The new theory allows to design and verify experimentally an artificial structure supporting a pure broadband toroidal dipole response in the complete absence of the electric dipole and other “ordinary” multipole contributions. In addition, a structure capable of supporting a novel type of non-radiating source is proposed- a “toroidal anapole,” originating from the destructive interference of the toroidal dipole with the unconventional electromagnetic sources known as mean square radii. The results in this work provide conclusive evidence on the independent excitation of toroidal moments in electrodynamics.     

Potential bounds in problems on quasilinear elliptic equations

We study quasilinear elliptic equations with strong nonlinear terms and systems of such equations. The methods developed by the authors in [1], [2] are used to prove the existence of solutions for boundary—value problems using some information on behavior of potential bounds for nonlinearities; the L–characteristics of elliptic operators and their fractional powers play an important role. New conditions are suggested for the existence of classical solutions of quasilinear second order elliptic equations.     

On the Minimum Distances of Non-Binary Cyclic Codes

We deal with the minimum distances of q-ary cyclic codes of length q ^m - 1 generated by products of two distinct minimal polynomials, give a necessary and sufficient condition for the case that the minimum distance is two, show that the minimum distance is at most three if q > 3, and consider also the case q = 3.     

U(1) gauge theory on a torus

U(1) gauge theory with the Villain action on a cubic lattice approximation of three- and four-dimensional torus is considered. As the lattice spacing approaches zero, provided the coupling constant correspondingly approaches zero, the naturally chosen correlation functions converge to the correlation functions of theR-gauge electrodynamics on three- and four-dimensional torus. When the torus radius tends to infinity these correlation functions converge to the correlation functions of theR-gauge Euclidean electrodynamics.Supported by the Russian Foundation of Fundamental Researches under Grant 93-011-147