A Cooperative Nearest Neighbours Topology Control Algorithm for Wireless Ad Hoc Networks

In this article, we introduce a simple distributed algorithm that assigns appropriate individual transmission powers to devices in a wireless ad hoc network. In contrast to many other proposed algorithms, it does without special hardware. It requires only local neighbourhood information and therefore avoids flooding information throughout the network. Finally, the cooperative nature of the algorithm avoids that devices cause excessive interference by using unnecessarily high transmission powers. By means of simulation, we show that the topologies created by this algorithm without any global knowledge are as effective as topologies resulting from a good choice of a common transmission power (which would require global knowledge) in terms of the achievable throughput. This work was supported in part by the German Federal Ministry of Education and Research (BMBF) as part of the IPonAir project.     

Fabrication and modification of polyvinylchloride based heterogeneous cation exchange membranes by simultaneously using Fe-Ni oxide nanoparticles and Ag nanolayer: Physico-chemical and antibacterial characteristics

Polyvinylchloride-blend-styrene butadiene rubber based nanocomposite cation exchange membranes were prepared by solution casting technique. Iron-oxide nanoparticles and Ag-nanolayer were simultaneously utilized as filler and surface modifier in membrane fabrication. The effects of Ag-nanolayer film thickness on membrane physicochemical and antibacterial characteristics of nanocomposite PVC-blend-SBR/Iron-oxide nanoparticles were studied. SEM images showed membrane roughness decreasing by Ag nanolayer thickness increasing. Membrane charge density and selectivity declined by Ag nanolayer coating up to 5 nm in membranes and then showed increasing trend by more nanolayer thickness. Ionic flux also showed increasing trend. Membranes showed good ability in E-Coli removal. 20 nm Ag-nanolayer coated membrane showed better performance compared to others.     

Preliminary investigation of factors determining self-organised structures preparation in polymer layers

Factors determining creation of self-organized structures, Bénar–Marangoni cells, during the process of solvent evaporation from the polymer solution and formation of polymer film were studied. Examined parameters were temperature, temperature gradient, rate of drying, height of a liquid layer, area for film preparation, viscosity, molecular weight distribution, etc. A special apparatus, micro condensation drying system, was engineered for this study. As a model system, hydroxyethyl cellulose aqueous solution was used for its excellent film-forming ability and the tendency to self-aggregation. Experimental results, presented in a wide spectrum of self-organized patterns, show the complexity of the problem and the crucial role of molecular weight distribution of the polymer in the fixation of organized structures under highly non-equilibrium conditions.     

Sabbatical leave: Who gains and how much?

A rigorous quasi-experiment tested the ameliorative effects of a sabbatical leave, a special case of respite from routine work. We hypothesized that (a) respite increases resource level and well-being and (b) individual differences and respite features moderate respite effects. A sample of 129 faculty members on sabbatical and 129 matched controls completed measures of resource gain, resource loss, and well-being before, during, and after the sabbatical. Among the sabbatees, resource loss declined and resource gain and well-being rose during the sabbatical. The comparison group showed no change. Moderation analysis revealed that those who reported higher respite self-efficacy and greater control, were more detached, had a more positive sabbatical experience, and spent their sabbatical outside their home country enjoyed more enhanced well-being than others. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Efficient Synthesis of α-Monoglycerides via Solventless Condensation of Fatty Acids with Glycerol Carbonate

Highly pure α-monoglycerides (5a–e) were successfully prepared in high yields by the condensation of fatty acids such as lauric, myristic, palmitic, stearic and oleic (2a–e) with glycerol carbonate (4-hydroxymethyl-1,3-dioxolan-2-one) (1) in the presence of triethylamine as catalyst. Reaction conditions and spectroscopic identification of products will be presented in this article.     

Low-Speed Atomistic Simulation of Stick–Slip Friction using Parallel Replica Dynamics

Atomic stick–slip friction has been predicted by molecular dynamics simulation and observed in experiments. However, direct quantitative comparison of the two has thus far not been possible because of the large difference between scanning velocities accessible to simulations and experiments. In general, the slowest sliding speeds in MD simulations are at least five orders of magnitude larger than the upper limit available to experimentalists. To take a step toward bridging this gap, we have applied parallel replica dynamics, an accelerated molecular dynamics method, to the simulation of atomic stick–slip. The method allows molecular simulations to run parallel in time in order to extend their duration, thereby enabling lower scanning velocities. We show here that this method is able to predict atomic stick–slip friction accurately and efficiently at scanning speeds several orders of magnitude slower than standard molecular dynamics simulations. The accuracy and usefulness of this method is illustrated by correct prediction of the logarithmic dependence of friction on velocity.     

Maternal High‐Fat‐Diet Programs Rat Offspring Liver Fatty Acid Metabolism

In offspring exposed in utero to a maternal diet high in fat (HF), we have previously demonstrated that despite similar birth weights, HF adult offspring at 6 months of age had significantly higher body weights, greater adiposity, and increased triacylglycerol (TAG) levels as compared to controls. We hypothesized that a maternal HF diet predisposes to offspring adiposity via a programmed increase in the synthesis of monounsaturated fatty acids in the liver and hence increased substrate availability for liver TAG synthesis. We further hypothesized that programmed changes in offspring liver fatty acid metabolism are associated with increased liver expression of the lipogenic enzyme stearoyl‐CoA desaturase‐1 (SCD‐1). Female rats were maintained on a HF diet rich in monounsaturated fatty acids (MUFA) prior to and throughout pregnancy and lactation. After birth, newborns were nursed by the same dam, and all offspring were weaned to control diet. Plasma and liver fatty acid compositions were determined using gas chromatography/mass spectrometry. Fatty acid C16 desaturation indices of palmitoleic/palmitic and (vaccenic + palmitoleic)/palmitic and the C18 desaturation index of oleic/stearic were calculated. Liver protein abundance of SCD‐1 was analyzed in newborns and adult offspring. Plasma and liver C16 desaturation indices were decreased in HF newborns, but increased in the adult offspring. Liver SCD‐1 expression was increased in the HF adult offspring. These data show that the maternal HF diet during pregnancy and lactation increases offspring liver SCD‐1 protein abundance and alters the liver C16 desaturase pathway.     

Kuwanon‐L as a New Allosteric HIV‐1 Integrase Inhibitor: Molecular Modeling and Biological Evaluation

HIV‐1 integrase (IN) active site inhibitors are the latest class of drugs approved for HIV treatment. The selection of IN strand‐transfer drug‐resistant HIV strains in patients supports the development of new agents that are active as allosteric IN inhibitors. Here, a docking‐based virtual screening has been applied to a small library of natural ligands to identify new allosteric IN inhibitors that target the sucrose binding pocket. From theoretical studies, kuwanon‐L emerged as the most promising binder and was thus selected for biological studies. Biochemical studies showed that kuwanon‐L is able to inhibit the HIV‐1 IN catalytic activity in the absence and in the presence of LEDGF/p75 protein, the IN dimerization, and the IN/LEDGF binding. Kuwanon‐L also inhibited HIV‐1 replication in cell cultures. Overall, docking and biochemical results suggest that kuwanon‐L binds to an allosteric binding pocket and can be considered an attractive lead for the development of new allosteric IN antiviral agents.