Synthesis of a new intercalating nucleic acid analogue with pyrenol insertions and the thermal stability of the resulting oligonucleotides towards DNA over RNA

Abstract  

A new intercalating nucleic acid monomer Y was obtained via alkylation of pyren-1-ol with (S)-(+)-2-(2,2-dimethyl-1,3-dioxolan-4-yl)ethanol under Mitsunobu conditions followed by hydrolysis with 80% aqueous acetic acid to give a diol which was tritylated with 4,4′-dimethoxytrityl chloride followed by treatment with 2-cyanoethyltetraisopropylphosphordiamidite in the presence of N,N′-diisopropylammonium tetrazolide. In this way the monomer Y was obtained as its dimethoxytrityl-protected phosphoramidite building block for standard DNA synthesis. The corresponding oligonucleotides from Y have nearly identical hybridization properties with those of intercalating nucleic acid (INA) where neighboring oxygen and carbon atoms are interchanged in the linker. The synthesis of monomer Y avoids the use of allergic intermediates which are a problem in the synthesis of INA.     

Transfer Hydrogenation of Acetophenone Catalyzed by in situ Generated 2,6-Bis(5-thioxo-4,5-dihydro-1,2,4-triazole- 3-yl)pyridine-ruthenium(II) Complexes

2,6-Bis(5-thioxo-4,5-dihydro-1,2,4-triazole-3-yl)pyridines (3, 4) were used for the first time as ligand in ruthenium catalyzed transfer hydrogenation of acetophenone. The in situ prepared three-component system Ru(II)/tridentate triamine ligands (3a—3d, 4a—4d) and KOH catalysed the transfer hydrogenation reaction of acetophenone in good yields under mild conditions.     

Identities for the Hankel transform and their applications

In the present paper the authors show that iterations of the Hankel transform with Kν-transform is a constant multiple of the Widder transform. Using these iteration identities, several Parseval-Goldstein type theorems for these transforms are given. By making use of these results a number of new Goldstein type exchange identities are obtained for these and the Laplace transform. The identities proven in this paper are shown to give rise to useful corollaries for evaluating infinite integrals of special functions. Some examples are also given as illustration of the results presented here.     

Formal verification of tail distribution bounds in the HOL theorem prover

Tail distribution bounds play a major role in the estimation of failure probabilities in performance and reliability analysis of systems. They are usually estimated using Markov's and Chebyshev's inequalities, which represent tail distribution bounds for a random variable in terms of its mean or variance. This paper presents the formal verification of Markov's and Chebyshev's inequalities for discrete random variables using a higher‐order‐logic theorem prover. The paper also provides the formal verification of mean and variance relations for some of the widely used discrete random variables, such as Uniform(m), Bernoulli(p), Geometric(p) and Binomial(m, p) random variables. This infrastructure allows us to precisely reason about the tail distribution properties and thus turns out to be quite useful for the analysis of systems used in safety‐critical domains, such as space, medicine or transportation. For illustration purposes, we present the performance analysis of the coupon collector's problem, a well‐known commercially used algorithm. Copyright © 2008 John Wiley & Sons, Ltd.     

A new approach to the characterization of the nano-surface structure by using factor analysis

The study provides a new approach to explore the existence of a nanostructure on the benzoic acid-modified glassy carbon electrode (BA-GC) system by applying factor analysis with varimax rotation of factors. The infrared spectra (IR) spectra of the bare glassy carbon electrodes (GC) and the BA-GC electrode systems with benzoic acid-nanofilm (BA-FILM) were obtained by using 10 different surface modification experiments. The IR data of the bare GC, BA-GC and BA-FILM were categorized into three series corresponding to the GC, BA-GC and BA-FILM. The factor analysis method was separately applied to each group to extract the factor loadings. By making use of these loadings, the rotated factor loadings corresponding to the first two factors were computed to estimate the relationship among and within groups. The results provided by the factor analysis method indicate the existence of the BA-FILM on the BA modified glassy carbon electrode.     

Controlling double-cavity optical switching in a K-type multilevel system including spontaneously generated coherence

A composite system consisting of a K-type atomic medium and a double optical cavity configuration is considered to study the phenomenon of atomic optical bistability (AOB) in the mean field approximation. The controllability of this phenomenon achieved by additional electromagnetic fields not circulating in the cavities is studied. Also, the effect of spontaneously generated coherence due to the quantum interference in decaying nearby levels on the multi-branched AOB is discussed. The system displays a new class of bifurcations.     

Gas‐phase pyrolytic reactions of N‐ethyl,N‐isopropyl,and N‐t‐butyl substituted 2‐aminopyrazine and 2‐aminopyrimidine

The rates of gas‐phase elimination of N‐ethyl (1), N‐isopropyl (2), N‐t‐butyl (3) substituted 2‐aminopyrazine and N‐ethyl (4), N‐isopropyl (5), and N‐t‐butyl (6) substituted 2‐aminopyrimidine have been measured. The compounds undergo unimolecular first‐order pyrolytic reactions. The relative rates of the primary:secondary;tertiary alkyl homologues at 600 K are 1:14.4:38.0 for the pyrazines and 1:20.8:162.5 for the pyrimidines, respectively. The reactivities of these compounds have been compared with those of the alkoxy analogues and with each other. Product analyses, together with the kinetic data, were used to outline a feasible pathway for the elimination reaction of the compounds under study. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 403–407, 2000     

Gas-phase kinetics of elimination reactions of pentane-2,4-dione derivatives. Part ii [1]. Thermolysis of derivatives and analogues of 3-phenylhydrazonopentane-2,4-dione

Six analogues and derivatives (1–6) of 3-phenylhydrazonopentane-2,4-dione (7) were subjected to gas-phase thermolysis. The Arrhenius log A (s⁻¹) and Ea (kJ mol⁻¹) of the analogues (1–5) are, respectively: 10.42 and 140.8 for 1-cyano-1-phenyl-hydrazonopropanone (1) , 11.19 and 135.4 for 1-cyano-1-( -nitrophenylhydrazono)-propanone (2) , 10.68 and 144.9 for 1-cyano-1-( -methoxyphenylhydrazono)propanone (3) , 11.76 and 137.8 for 1-cyano-3-phenyl-1-phenylhydrazonopropanone (4) , and 11.29 and 145.9 for 1-cyano-1-phenylhydrazonobutanone (5) . The corresponding values for ethyl 3-oxo-2-phenylhydrazonobutanoate (6) are 11.90 s⁻¹ and 143.3 kJ mol⁻¹. The rates of reaction at 600 K are compared with those of the title diketone (7) and of pentane-2,4-dione (8) and rationalized in terms of a plausible elimination pathway involving a semiconcerted six-membered transition state. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 457–462, 1998     

The Involvement of l-Arginine-Nitric Oxide-cGMP-ATP-Sensitive K+ Channel Pathway in Antinociception of BBHC,a Novel Diarylpentanoid Analogue,in Mice Model

The present study focuses on the possible involvement of l-arginine-nitric oxide-cGMP-ATP-sensitive K⁺ channel pathway in the antinociceptive activity of a novel diarylpentanoid analogue, 2-benzoyl-6-(3-bromo-4-hydroxybenzylidene)cyclohexen-1-ol (BBHC) via a chemical nociceptive model in mice. The antinociceptive action of BBHC (1 mg/kg, i.p.) was attenuated by the intraperitoneal pre-treatment of l-arginine (a nitric oxide synthase precursor) and glibenclamide (an ATP-sensitive K⁺ channel blocker) in acetic acid-induced abdominal constriction tests. Interestingly, BBHC’s antinociception was significantly enhanced by the i.p. pre-treatment of 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), a selective inhibitor of soluble guanylyl cyclase (p < 0.05). Altogether, these findings suggest that the systemic administration of BBHC is able to establish a significant antinociceptive effect in a mice model of chemically induced pain. BBHC’s antinociception is shown to be mediated by the involvement of l-arginine-nitric oxide-cGMP-ATP-sensitive K⁺ channel pathway, without any potential sedative or muscle relaxant concerns.     

High‐Density Polyethylene Micro‐ and Nanocomposites: Effect of Particle Shape,Size and Surface Treatment on Polymer Crystallinity and Gas Permeability

Summary: High‐density polyethylene (HDPE) micro‐ and nanocomposites with spherical and platelike inclusions were prepared and the effect of filler particles on polymer crystallinity and gas permeability was investigated. Platelike inclusions strongly reduce the polymer permeability coefficient, while spherical ones have no influence on it, irrespective of their size. The reduction in gas permeability depends on the average aspect ratio of the inclusions, which in turn depends on the exfoliation of the organo‐montmorillonites (OM) and consequently on its surface treatment.

A TEM micrograph of 3 vol.‐% 2C18 · M‐HDPE nanocomposite, showing partial exfoliation of the organo‐montmorillonite.