Efficient palladium-catalyzed nucleophilic addition of triorganoindium reagents to carbocyclic derivatives

Palladium (0)-catalyzed allylic substitution reactions employing triorganoindium reagents have been investigated. In situ generated vinyl- and arylindiums react with substituted and unsubstituted cyclohex-2-enyl esters in the presence of 1-3 mol % Pd(2)(dba)(3) to produce vinyl- or arylcyclohexenes in moderate to excellent yields. The stereoselectivity of this process was also examined, and evidence is presented that the reaction proceeds with inversion of stereochemical configuration.     

Syntheses of 3,7-dimethylpentadecan-2-ols from intermediates formed from co-oligomerisation reactions of butadiene with diethyl malonate and acetaldehyde

The products of the reaction of butadiene with diethyl malonate catalysed by a palladium complex and of butadiene with acetaldehyde catalysed by a nickel(0) complex have been used in two syntheses of 3,7-dimethylpentadecan-2-ol.     

Formation of carbon oxides during tobacco combustion: Pyrolysis studies in the presence of isotopic gases to elucidate reaction sequence

During the combustion of tobacco, carbon monoxide is formed by the thermal decomposition of tobacco with primary products such as carbon dioxide and water. These three processes occur in parallel and are interdependent. The temperature ranges over which each process occurs, and their relative importance have been assessed by pyrolysing tobacco in the presence of various isotopically labelled gases. Non-isothermal pyrolyses were conducted at a heating rate of 1.6 K s^?1 up to 1000°C, with the products analysed by mass spectrometer.Pyrolysis in the presence of oxygen-18 indicates that combustion of tobacco starts at 180°C. Carbon dioxide and water are formed by combustion at 180°C, while carbon monoxide is not formed as a combustion product until 460°C. The quantities of carbon monoxide and dioxide formed by thermal decomposition of tobacco above 400°C are significantly reduced by the occurrence of combustion.Pyrolysis in the presence of carbon-13 dioxide or carbon dioxide-18 shows that its major reaction, endothermic reduction to form carbon monoxide begins at 450°C. Pyrolysis in an oxygen-18/carbon-13 dioxide atmosphere has shown that this endothermic reduction of carbon dioxide occurs in parallel with the strongly exothermic oxidising reactions. 30% of the total carbon monoxide formed was produced by thermal decomposition of the tobacco. 36% was produced by combustion of the tobacco, and at least 23% was produced via carbon dioxide. The remainder was produced by an interaction of the carbon dioxide reduction and the oxidation. Similar proportion would be expected inside the reaction zone of a burning cigarette.Pyrolysis in the presence of heavy water has shown that the major reaction of the water is to quantitatively produce carbon monoxide and hydrogen above 600°C. Considerable isotopic exchange reactions also occur. Pyrolysis in the presence of carbon monoxide-18 has shown that carbon monoxide reacts with tobacco to a small extent at temperatures above 220°C mainly to abstract oxygen combined in the tobacco and produce carbon dioxide.A sequence of general chemical steps for the production of the carbon oxides and water during tobacco combustion has been deduced. This is based on the present work together with considerations of previously published studies on graphite and coal reactions.     

Inhibition by protease inhibitors of binding of adrenal and sex steroid hormones.

Binding of steroid hormones is inhibited by protease inhibitors and substrates. The protease inhibitors phenylmethyl sulphonylfluoride, tosyl-lysine chloromethyl ketone, and tosylamide-phenylethyl-chloromethyl ketone and the protease substrates tosyl arginine methyl ester and tryptophan methyl ester eliminate specific binding of aldosterone, dexamethasone, dihydrotestosterone, estrogen, and progesterone to their respective receptors. These protease inhibitors and substrates also inhibit binding of progesterone to the 20,000 molecular weight mero-receptor formed from the progesterone receptor in chick oviduct. The binding of estradiol to rat alpha-fetoprotein is inhibited by the protease inhibitors and substrates but not by tryptophan or tryptophan amide, indicating the importance of an ester structure in the inhibition of steroid binding. Our results suggest that all steroid hormone receptors have a site with both common structural features and a role in the regulation of steroid hormone binding.     

Protein biosensors based on biofunctionalized conical gold nanotubes

There is increasing interest in the concept of using nanopores as the sensing elements in biosensors. The nanopore most often used is the alpha-hemolysin protein channel, and the sensor consists of a single channel embedded within a lipid bilayer membrane. An ionic current is passed through the channel, and analyte species are detected as transient blocks in this current associated with translocation of the analyte through the channel-stochastic sensing. While this is an extremely promising sensing paradigm, it would be advantageous to eliminate the very fragile lipid bilayer membrane and perhaps to replace the biological nanopore with an abiotic equivalent. We describe here a new family of protein biosensors that are based on conically shaped gold nanotubes embedded within a mechanical and chemically robust polymeric membrane. While these sensors also function by passing an ion current through the nanotube, the sensing paradigm is different from the previous devices in that a transient change in the current is not observed. Instead, the protein analyte binds to a biochemical molecular-recognition agent at the mouth of the conical nanotube, resulting in complete blockage of the ion current. Three different molecular-recognition agents, and correspondingly three different protein analytes, were investigated: (i) biotin/streptavidin, (ii) protein-G/immunoglobulin, and (iii) an antibody to the protein ricin with ricin as the analyte.     

Elliptic Genera of Level N and Elliptic Cohomology

Elliptic genera of level N have been defined by F. Hirzebruch,generalising the earlier notion of elliptic genus due to S.Ochanine. We show that there are corresponding elliptic cohomologytheories which are naturally associated to such genera and thatthese are obtained from the level 1 case by algebraic extensionof the coefficient rings from level 1 to level N modular forms.     

Functional Equations and Weierstrass Transforms

The purpose of this article is to illustrate the utility of the Weierstrass transform in the study of functional equations (and systems) of the form 1 $${\mathop \sum^N\limits_{k=0}}\alpha_{k}f(x+r_{k})=f_{0}(x)\ \ \ \, x\in\ {\rm R}.$$ One may think of α₀, α₁,…, α_N as given complex numbers, r₀, r₁,…, r_N as given real numbers, ?₀: ? → C as a given function and ? as the unknown.     

A Bruen chain forq=19

The one-to-one correspondence between the class of two-dimensional translation planes of orderq ² and the collection of spreads ofPG(3,q) has long provided a natural context for describing new planes. The method often used for constructing interesting spreads is to start with a regular spread, corresponding to a desarguesian plane, and then replace some nice subset of lines by another partial spread covering the same set of points. Indeed the first approach was replacing the lines of a regulus by the lines of its opposite regulus, or doing this process for a set of disjoint reguli. Nontrivial generalizations of this idea include thechains of Bruen and thenests of Baker and Ebert. In this paper we construct a replaceable subset of a regular spread ofPG (3, 19) which is the union of 11 reguli double covering the lines in their union, hence is a chain in the terminology of Bruen or a 11-nest in the Baker-Ebert terminology.