Chemical reactions of double bonds in activated carbon: microwave and bromination methods

The reaction of localised C[double bond, length as m-dash]C bonds on the surface of activated carbons has been shown to be an effective method of chemical modification especially using microwave-assisted reactions.     

STUDIES OF ADHESION OF METAL PARTICLES TO SILICA PARTICLES BASED ON ZETA POTENTIAL MEASUREMENTS

The zeta-potentials of silica, copper, platinum and gold particles have been measured as a function of pH. The isoelectric points were found to be at pH 3.0, 5.8, 3.0 and 3.5, respectively. In the pH range 3.0 to 5.8 copper and silica particles are oppositely charged and accordingly the coating of silica with copper particles could be demonstrated. In the case of gold and platinum the sign of the charge is such that direct adhesion to silica particles cannot be expected and this was also demonstrated in the case of platinum.     

Buckling of coupled elastic rods

A simple physical system is studied which demonstrates the unfolding of a multiple bifurcation point. Two coupled elastic rods are subjected to a compressive load. The rods are joined such that their buckling directions are orthogonal. As the load is quasistatically increased from zero one of the two rods will buckle independently of the other. The “preferred” buckling mode is determined by two parameters, the length ratio and the stiffness ratio. The experimental system consists of two spring steel strips joined through a Teflon connector such that the buckling planes are orthogonal. The theoretical model consists of an analogous rigid rod and spring model which we assume retains the essential features of the continous system. Secondary bifurcation is essential to a continuous exchange of priority between the two buckling modes, and its role is examined for both imperfection-free and perturbed rod-spring systems. Our computational results are then compared with some experiments.     

Flow in a symmetric channel with an expanded section

We consider the flow in a symmetric two-dimensional channel with an expanded section. By examining the effect of varying the ratio of the inlet and outlet channel widths, we are able to place the earlier results of Mizushima et al. (Phys. Fluids 8 (1996) 2933) within an entire spectrum of nonlinear phenomena. Laboratory experiments support predicted behaviour in two regions of parameter space and highlight the importance of imperfections in the experimental apparatus.     

<Emphasis Type="Italic">N</Emphasis>-arachidonoyl glycine,an abundant endogenous lipid,potently drives directed cellular migration through GPR18, the putative abnormal cannabidiol receptor

Background  

Microglia provide continuous immune surveillance of the CNS and upon activation rapidly change phenotype to express receptors that respond to chemoattractants during CNS damage or infection. These activated microglia undergo directed migration towards affected tissue. Importantly, the molecular species of chemoattractant encountered determines if microglia respond with pro- or anti-inflammatory behaviour, yet the signaling molecules that trigger migration remain poorly understood. The endogenous cannabinoid system regulates microglial migration via CB₂ receptors and an as yet unidentified GPCR termed the 'abnormal cannabidiol' (Abn-CBD) receptor. Abn-CBD is a synthetic isomer of the phytocannabinoid cannabidiol (CBD) and is inactive at CB₁ or CB₂ receptors, but functions as a selective agonist at this G_i/o-coupled GPCR. N-arachidonoyl glycine (NAGly) is an endogenous metabolite of the endocannabinoid anandamide and acts as an efficacious agonist at GPR18. Here, we investigate the relationship between NAGly, Abn-CBD, the unidentified 'Abn-CBD' receptor, GPR18, and BV-2 microglial migration.     

Numerical analysis and adaptive computation for solutions of elliptic problems with randomly perturbed coefficients

We develop a reliable efficient method for computing solutions to the Poisson equation a with randomly perturbed coefficient. We assume the perturbation to be piecewise constant and use a non-overlapping domain decomposition algorithm, where the domains coincides with regions where the perturbation is constant, to solve the equations. On each sub-domain we use an truncated Neumann series to approximate the inverse of the local stiffness matrix. By doing so we can solve for all samples simultaneously in a very efficient way. We derive a posteriori error estimates and construct an adaptive algorithm to tune the method parameters automatically. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)