Generalized steiner problem in series-parallel networks

The generalized Steiner problem (GSP) is concerned with the determination of a minimum cost subnetwork of a given network where some (not necessarily all) vertices satisfy certain pairwise (vertex or edge) connectivity requirements. The GSP has applications to the design of water and electricity supply networks, communication networks and other large-scale systems where connectivity requirements ensure the communication between the selected vertices when some vertices and/or edges can become inoperational due to scheduled maintenance, error, or overload. The GSP is known to be NP-complete. In this paper we show that if the subnetwork is required to be respectively biconnected and edge-biconnected, and the underlying network is series-parallel, both problems can be solved in linear time.     

Null Sequences in Coechelon Spaces

Rotundity of finite -dimensional Orlicz spaces l^?_n equipped with the Luxemburg norm is considered. It is proved that criteria for rotundity of l^?_nfor n ≥ 3 does not depend on n and are the same as the criteria for rotundity of the inhite-dimensional subspace h^? of an Orlicz sequence spacel^?. Criteria for rotundity of l^?₂ are different. Next, criteria for exposed points, (H)- points, strongly exposed points and LUR- points of the unit sphere of l^? and of its subspace h^? are given.     

Formation of ultra-thin prussian blue layer on carbon steel that promotes adherence of hybrid polypyrrole based protective coating

Electrodeposition of well-adhering polypyrrole-based hybrid films containing hexacyanoferrate(II,III) anions from neutral solutions of pyrrole and potassium hexacyanoferrate(II) on medium carbon (0.48% C) steel has been described. The resulting polypyrrole coatings that are doped with hexacyanoferrate(II,III) anions show protective properties against pitting corrosion of carbon steel substrates in strongly acidic media containing chlorides (0.1 mol dm^–3 HCl + 0.4 mol dm^–3 NaCl). Polypyrrole acts as a stable host matrix for inorganic anions. The presence of negatively charged species (hexacyanoferrates) in the polymer backbone tends to block the access of pitting-causing anions (chlorides) to the surface of steel. The Fe(CN)₆^3-/4– anions existing in the vicinity of steel substrate stabilizes its surface by forming an overcoating in the form of sparingly soluble metal hexacyanoferrate, mostly Prussian blue (PB), microstructures. It has been demonstrated that by applying cyclic voltammetry and X-ray photoelectron spectroscopy, the presence of traces of free cyanide anions promotes the formation of PB on carbon steel surface which results in increasing the adherence of polypyrrole-based films to the metallic substrate. Morphology of the protective composite films is also addressed.Dedicated to Prof. G. Horanyi on the occasion of his 70th birthday     

Alkaloid Production in Catharanthus roseus Cell Cultures. VII.. Effect of parameter changes and catabolism studies on cell line PRL No. 953

Catharanthus roseus cells suspended in production medium showed the presence of four Aspidosperma-type alkaloids, however, no vindoline. Cells grown in media with the pH adjusted to 7.0 produced 3.3 mg total alkaloids/g dry weight. At pH 5.0, 1.7 mg of alkaloid/g dry weight was produced. (S)-Adenosyl-methionine did not stimulate the production of vindoline. When added to cell suspensions for 21 days, vindoline and catharanthine were degraded to non-alkaloidal substances, not dimerized to bisindole alkaloids.     

First example of the chemical, oxidative cleavage of the C-P bond in aminophosphonate chemistry. The oxidation of 1-amino-1-(3,4-dihydroxyphenyl)methylphosphonic acid by NaIO4

Oxidative, chemical cleavage of the C-P bond in 1-amino-1-(3,4-dihydroxyphenyl)methylphosphonic acid upon the action of NaIO(4) have been the subject of the NMR, EPR and UV-Vis investigations in acidic and basic conditions.     

Chlorella virus pyrimidine dimer glycosylase excises ultraviolet radiation- and hydroxyl radical-induced products 4,6-diamino-5-formamidopyrimidine and 2,6-diamino-4-hydroxy-5-formamidopyrimidine from DNA

A DNA glycosylase specific for UV radiation-induced pyrimidine dimers has been identified from the Chlorella virus Paramecium Bursaria Chlorella virus-1. This enzyme (Chlorella virus pyrimidine dimer glycosylase [cv-pdg]) exhibits a 41% amino acid identity with endonuclease V from bacteriophage T4 (T4 pyrimidine dimer glycosylase [T4-pdg]), which is also specific for pyrimidine dimers. However, cv-pdg possesses a higher catalytic efficiency and broader substrate specificity than T4-pdg. The latter excises 4,6-diamino-5-formamidopyrimidine (FapyAde), a UV radiation- and hydroxyl radical-induced monomeric product of adenine in DNA. Using gas chromatography-isotope-dilution mass spectrometry and y-irradiated DNA, we show in this work that cv-pdg also displays a catalytic activity for excision of FapyAde and, in addition, it excises 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua). Kinetic data show that FapyAde is a better substrate for cv-pdg than FapyGua. On the other hand, cv-pdg possesses a greater efficiency for the extension of FapyAde than T4-pdg. These two enzymes exhibit different substrate specificities despite substantial structural similarities.     

Polyoxometallates as inorganic templates for electrocatalytic network films of ultra-thin conducting polymers and platinum nanoparticles

We develop a concept of fabrication of the multilayer network films on electrodes by exploring the ability of a Keggin-type polyoxometallate, phosphododecamolybdate (PMo(12)O(40)(3-)), to form stable anionic monolayers (templates) on carbon and metals including platinum. By repeated alternate treatments in the solution of PMo(12)O(40)(3-) (or in the colloidal suspension of polyoxometallate-protected Pt-nanoparticles) and in the solution of monomer (e.g. anilinium) cations, the amount of the material can be increased systematically (layer-by-layer) to form stable three-dimensional assemblies on electrode (e.g. glassy carbon) surfaces. In the resulting hybrid (organic-inorganic) films, the layers of negatively charged polyoxometallate, or polyoxometallate-protected (stabilized) Pt-nanoparticles, are linked or electrostatically attracted by ultra-thin layers of such positively charged conducting polymers as polyaniline (PANI), polypyrrole (PPy) or poly(3,4-ethylenedioxythiophene), PEDOT. Consequently, the attractive physicochemical properties of polymers and reactivity of polyoxometallate or noble metal particles are combined. The films are functionalized and show electrocatalytic properties towards reduction of nitrite, bromate, hydrogen peroxide or oxygen. They are of importance to the chemical and biochemical sensing as well as to the biochemical and medical applications.     

Matrix elements for Ĵ2 and Ĵz operators over explicitly correlated Cartesian Gaussian functions

General formalism for evaluation of multiparticle integrals involving J?² and J?_z operators over explicitly correlated Cartesian Gaussian functions is presented. The integrals are expressed in terms of the general overlap integrals. An explicitly correlated Cartesian Gaussian function is a product of spherical orbital Gaussian functions, powers of the Cartesian coordinates of the particle, and exponential Gaussian factors, which depend on interparticular distances. This development is relevant to both adiabatic and nonadiabatic calculations of energy and properties of multiparticle systems. © 1995 John Wiley & Sons, Inc.     

Novel photoacid generators for photodirected oligonucleotide synthesis

Photodirected oligonucleotide synthesis uses either direct or indirect light-dependent 5'-deprotection. Both have been reported to give lower stepwise synthetic yields than conventional methods. The deficiency appears to be due to incomplete deprotection at the oligonucleotide 5'-position and, additionally in the case where photodirection is indirect and uses photogenerated photoacid to effect 5'-detritylation, the depurinating effects of strong acid. We have developed novel photosensitive-2-nitrobenzyl esters that on irradiation with near UV light generate alpha-chloro-substituted acetic acids, such as trichloroacetic acid, which are widely and successfully used in conventional solid-phase oligonucleotide synthesis. alpha-Phenyl-4,5-dimethoxy-2-nitrobenzyltrichloroacetate and alpha-phenyl-4,5-dimethoxy-2,6-dinitrobenzyltrichloroacetate showed appropriate photochemical characteristics and were used for photodirected synthesis of a variety of oligonucleotides, including (T)(5), TATAT, TGTGT, (T)(10), (AT)(5), (CT)(5) (GT)(5), and (TGCAT)(2) on a modified Millipore Expedite DNA synthesizer. The outcomes were compared with those obtained by use of directly added trichloroacetic acid (conventional synthesis). The stepwise yields for the two methods were essentially identical.     

Study of complexation in the Nd3+-SCN− system

Summary A spectroscopic study of the association in the Nd³⁺-SCN^– system is presented. A characteristic change of the molar absorptivity of the solution with a plateau at 2–4M [SCN^–] and an increase at 4–8M [SCN^–] reflects the change from outer- to innersphere complexation.

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Untersuchungen zur Komplexierung im Nd³⁺-SCN^–-System

Zusammenfassung Es wird eine spektroskopische Studie der Assioziationsverhältnisse im Nd³⁺-SCN^–-System präsentiert. Die charakteristische Änderung in der molaren Absorption der Lösung mit einem Plateau bei 2–4M [SCN^–] und ein Anstieg bei 4–8M [SCN^–] ist auf einen Wechsel von außensphärischer zu innensphärischer Komplexierung zurückzuführen.