Biosynthesis of galactomannan in the endosperms of developing fenugreek (Trigonella foenum-graecum L.) and guar (Cyamopsis tetragonoloba [L.] Taub.) seeds

The biosynthesis of galactomannan in vitro has been demonstrated conclusively using particulate enzyme preparations from the developing endosperms of fenugreek and guar and the sugar nucleotides GDP-D-mannose and UDP-D-galactose. Furthermore the mannose: galactose (man:gal) ratio in the products formed in vitro has been manipulated. These results are discussed in the context of possible mechanisms for the control of man:gal ratio in vivo.     

Exploring the unique pharmacology of a novel opioid receptor, ZFOR1, using molecular modeling and the `message-address' concept

Previous studies have probed the structural basis of ligandselectivity in the mu, delta and kappa opioid receptors throughthe application of molecular modeling techniques in concertwith the `message–address' concept. Here, this approachwas used in an attempt to rationalize the unique pharmacologicalprofile of a recently cloned novel opioid receptor, ZFOR1 (ZebraFishOpioid Receptor 1). Specifically, a model of the transmembranedomains of ZFOR1 was constructed and used to explore the bindingmodes of various prototypical opioid ligands. The results showthat the `message' portion of the binding pocket of ZFOR1 ishighly conserved; hence, the binding modes of non-selectiveopioid ligands are well preserved. In contrast, a small numberof variant residues at the extracellular end of the bindingpocket, particularly Lys288 (VI:26) and Trp304 (VII:03), areshown to create adverse steric interactions with all delta andkappa selective ligands examined, thereby disrupting their bindingmodes. These results are consistent with, and serve as an explanationfor, the observed pharmacology of this receptor, lending supportto both the validity of the `message–address' conceptitself and to the use of molecular modeling approaches in itsapplication.     

Computational model of three-dimensional cardiac electromechanics

We coupled a continuum model of impulse propagation with a three-dimensional model of regional ventricular mechanics. Equations for action potential propagation, myofilament activation and active contraction were solved in an anatomically detailed finite element model of canine left and right ventricular geometry, muscle fiber architecture and Purkinje fiber network anatomy. Finite element equations for time-dependent excitation and recovery variables were assembled using a collocation method and solved using adaptive Runge-Kutta integration. Resting tissue mechanics were modeled as nonlinear, orthotropic and hyperelastic. A Windkessel model for arterial impedance was coupled to ventricular pressure and volume to compute hemodynamic boundary conditions during ejection. Ventricular volume constraints were imposed during the isovolumic phases. This model showed good agreement in the time course of regional systolic strains with experimental measurements during normal sinus rhythm and demonstrates the importance of the Purkinje fiber system in determining the mechanical activation sequence.     

The Influence of Film Morphology in High‐Mobility Small‐Molecule:Polymer Blend Organic Transistors

Organic field‐effect transistors (OFETs) based upon blends of small molecular semiconductors and polymers show promise for high performance organic electronics applications. Here the charge transport characteristics of high mobility p‐channel organic transistors based on 2,8‐difluoro‐5,11‐bis(triethylsilylethynyl) anthradithiophene:poly(triarylamine) blend films are investigated. By simple alteration of the film processing conditions two distinct film microstructures can be obtained: one characterized by small spherulitic grains (SG) and one by large grains (LG). Charge transport measurements reveal thermally activated hole transport in both SG and LG film microstructures with two distinct temperature regimes. For temperatures >115 K, gate voltage dependent activation energies (E_A) in the range of 25–60 meV are derived. At temperatures <115 K, the activation energies are smaller and typically in the range 5–30 meV. For both film microstructures hole transport appears to be dominated by trapping at the grain boundaries. Estimates of the trap densities suggests that LG films with fewer grain boundaries are characterized by a reduced number of traps that are less energetically disordered but deeper in energy than for small SG films. The effects of source and drain electrode treatment with self‐assembled monolayers (SAMs) on current injection is also investigated. Fluorinated thiol SAMs were found to alter the work function of gold electrodes by up to ～1 eV leading to a lower contact resistance. However, charge transport analysis suggests that electrode work function is not the only parameter to consider for efficient charge injection.     

SwarmDock and the Use of Normal Modes in Protein-Protein Docking

Here is presented an investigation of the use of normal modes in protein-protein docking, both in theory and in practice. Upper limits of the ability of normal modes to capture the unbound to bound conformational change are calculated on a large test set, with particular focus on the binding interface, the subset of residues from which the binding energy is calculated. Further, the SwarmDock algorithm is presented, to demonstrate that the modelling of conformational change as a linear combination of normal modes is an effective method of modelling flexibility in protein-protein docking.     

Efficient,high photostability,high brightness,co-polymer solid state dye lasers

Abstract

We report an investigation of the laser beam quality, efficiency and photostability of rhodamine 590 solid state dye lasers with hosts based upon 2-hydroxyethylmethacrylate and methylmethacrylate P(HEMA:MMA) co-polymers and modified methylmethacrylate (MPMMA) polymers with ethanol and dimethylsulphoxide additives. Highest efficiencies were obtained with MPMMA, with slope efficiencies of up to 44% (corresponding to 61% optical-optical conversion) measured for ethanolic MPMMA. P(HEMA:MMA) hosts gave superior photostability, with the highest normalized photostability of 240 GJ mol^?1 obtained for a P(HEMA:MMA) 1:1 rod. A simple resonator has been used to compensate the effects of thermal lensing and pump mode-mismatch, resulting in optimized beam quality for MPMMA lasers.     

The Production of Low-Alcohol Wines by Aerobic Yeasts

Aerobic yeasts of the genera Pichia and Williopis are commonly regarded as spoilage yeasts of beer and wine by causing turbidity, a surface film of yeast growth and often an excessive estery flavour. However, their ability to utilise sugars oxidatively for cell growth with the production of estery and other flavours of wine with only minimal production of ethanol suggests a method for the production of low-alcohol wines of pleasant “fermented” flavour without the need for additional equipment to remove alcohol by dialysis, reverse osmosis or distillation, or without the excessive sweetness remaining from arrested fermentation. Three strains of Pichia and one of Williopsis were examined for their ability to produce approximately 3%(v/v) ethanol and a good estery and fruity flavour. With normal anaerobic fermentation conditions, or with gentle stirring to prevent formation of a surface film, excessive amounts of alcohol were produced from grape juice of 15% or 20% (w/v) initial sugar concentration. However, an acceptably flavoured wine of alcohol content < 3% was produced by agitation and aeration during fermentation. The ethanol formed in the early stages of culture was oxidised to a final level < 3%, with the production of cell mass and an acceptable flavour.     

Studying protein–ligand interactions using protein crystallography

Protein X-ray crystallography is now a relatively high-throughput technique that plays a major role in structure-based drug design programs where the method of soaking small organic ligands into protein crystals is used to confirm or identify binding modes. In this review, we discuss some experimental approaches for ‘soaking-in’ ligands into protein crystals where the major problem is poor solubility of the ligand. We also provide examples showing how crystal soaking can be used as a technique for establishing ligand binding strength: K _c (the apparent ligand–protein dissociation constant in the crystal), which for some proteins at least, is found to be very similar to the solution K _d. Kinetic effects are also found to be important and the rate at which ligands soak into crystals is shown to vary by orders of magnitude from 10^?1 to 10⁷?s depending on the system.     

Cathode ray tube bleed resistor reliability—a case study

This paper describes, and gives a mathematical analysis of, the performance of two makes of CRT bleed resistors which exhibit markedly different characteristics under heat soak conditions. By examining the observed resistance changes with temperature, and relating these to the Arrhenius equation, the reaction activation energies can be determined. Further analysis of the power consumption characteristics of the resistors leads to the establishment of resistance-time curves for both makes of resistor. These indicate very different conclusions than might otherwise have been drawn from initial test data. Finally the Monte Carlo' simulation technique is used to determine the most likely survival characteristics in a field situation, and a quantitative assessment of the reliability of CRTs using these bleed resistors is given. The construction of the resistor body is common to both makes and comprises a resistor substrate enclosed within an overcoat which is in turn encapsulated in epoxy. One make (type A) is a glass thick film structure, whereas the other is a polymer thick film system.     

The governance challenge for implementing effective market-based climate policies: A case study of The New South Wales Greenhouse Gas Reduction Scheme

The New South Wales (NSW) Greenhouse Gas Reduction Scheme (GGAS) in Australia is a baseline and credit emissions trading scheme with the stated aim of reducing the per-capita greenhouse emissions associated with electricity consumption in the state of NSW. Here we provide a detailed assessment of the GGAS design and operation, with a particular emphasis on its effectiveness in delivering physical emissions reductions that would not have occurred in its absence. We find that a number of design features mean a significant proportion of the tradeable ‘abatement’ certificates are unlikely to correspond to the claimed emissions reductions. While some of these adverse design choices might be corrected, others would seem inherent to the underlying scheme design. Our analysis highlights the major governance challenges with emissions trading approaches and hence the importance of good policy implementation processes including the need for separation of powers through a scheme development process that involves design, assessment and revision. These GGAS lessons would seem relevant for governance with all emissions trading schemes, and has particular implications for cap and trade schemes that incorporate baseline and credit offset schemes, as well as to the ‘White Certificate’ schemes increasingly being seen as a means of fostering enhanced end-use energy efficiency.