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Odontotermes hainanensis Light is known as a pest to structures, crops, dikes and dams in Vietnam that needs to be controlled. Currently, termite control using baits is considered a preeminent especially environmentally friendly measure. However, applying this method has been proven to be incapable to control Odontotermes hainanensis or other fungus-growing termites (the subfamily Macrotermitinae) due to their complex food processing. The research on food processing and the food distribution ability within the colony of this species was conducted in order to identify a scientific basis to further enhance the efficiency when treating them with baits. Results on the food processing of laboratory cultured colonies showed that this process took from 21 to 35 days with labor division in worker groups. Results on food transferring by food marking method in the field colonies showed that food was distributed by workers to most of the fungus garden cavities of the colonies. The proportion of cavities that fungus combs containing marking food reached from 92.1% to 100% in these studied nests. This is an essential scientific basis for the termite bait study on controlling the fungus-growing termites, particularly Odondon hainanensis. [ABSTRACT FROM AUTHOR]

Establishing the relation between the structures and functions of protein ion channels, which are protein assemblies that facilitate transmembrane ion transport through water-filled pores, is at the forefront of biological and medical sciences. A reliable way to determine whether our understanding of this relation is satisfactory is to reproduce the measured ionic conductance over a broad range of applied voltages. This can be done in molecular dynamics simulations by way of applying an external electric field to the system and counting the number of ions that traverse the channel per unit time. Since this approach is computationally very expensive we develop a markedly more efficient alternative in which molecular dynamics is combined with an electrodiffusion equation. This alternative approach applies if steady-state ion transport through channels can be described with sufficient accuracy by the one-dimensional diffusion equation in the potential given by the free energy profile and applied voltage. The theory refers only to line densities of ions in the channel and, therefore, avoids ambiguities related to determining the surface area of the channel near its endpoints or other procedures connecting the line and bulk ion densities. We apply the theory to a simple, model system based on the trichotoxin channel. We test the assumptions of the electrodiffusion equation, and determine the precision and consistency of the calculated conductance. We demonstrate that it is possible to calculate current/voltage dependence and accurately reconstruct the underlying (equilibrium) free energy profile, all from molecular dynamics simulations at a single voltage. The approach developed here applies to other channels that satisfy the conditions of the electrodiffusion equation. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations were used to study the structural perturbations of lipids surrounding transmembrane ion channel forming helices/helical bundles and the movement of water within the pores of the ion-channels/bundles. Specifically, helical monomers to hexameric helical bundles embedded in palmitoyl-oleoyl-phosphatidyl-choline (POPC) lipid bilayer were studied. Two amphipathic a-helices with the sequence Ac-(LSLLLSL)3-NH2 (LS2), and Ac-(LSSLLSL)3-NH2 (LS3), which are known to form ion channels, were used. To investigate the surrounding lipid environment, we examined the hydrophobic mismatch, acyl chain order parameter profiles, lipid head-to-tail vector projection on the membrane surface, and the lipid headgroup vector projection. We find that the lipid structure is perturbed within approximately two lipid solvation shells from the protein bundle for each system (~15.0 Å). Beyond two lipid ?solvation? shells bulk lipid bilayer properties were observed in all systems. To understand water flow, we enumerated each time a water molecule enters or exited the channel, which allowed us to calculate the number of water crossing events and their rates, and the residence time of water in the channel. We correlate the rate of water crossing with the structural properties of these ion channels and find that the movements of water are predominantly governed by the packing and pore diameter, rather than the topology of each peptide or the pore (hydrophobic or hydrophilic). We show that the crossing events of water fit quantitatively to a stochastic process and that water molecules are traveling diffusively through the pores. These lipid and water findings can be used for understanding the environment within and around ion channels. Furthermore, these findings can benefit various research areas such as rational design of novel therapeutics, in which the drug interacts with membranes and transmembrane proteins to enhance the efficacy or reduce off-target effects. [ABSTRACT FROM AUTHOR]

This paper analyses the economics of cogeneration potential in the pulp and paper industry of Vietnam. The analysis focuses on six large existing paper mills, their planned capacity expansion and nine planned new mills up to 2010. The analysis considered five alternative fuels (coal, diesel, fuel oil, natural gas and rice husk), three different technologies (steam turbines, gas turbines and reciprocating engines) and two modes of operation (thermal match and power match) of cogeneration. It also considered the case of sale of excess power to the grid. The analysis indicates that cogeneration is a viable option in the paper and pulp industry in Vietnam and the potential is about 200 MW. IRR in most of the cases ranges between 15 and 30% and the general payback period is between 3 and 5 years. Cogeneration remains a viable option even without sale of power to the grid and under different unfavourable conditions of fuel price, investment and other factors. Copyright © 2005 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]