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.     

Current saturation in CdS

An iteration procedure for calculating the high electric fields found in piezoelectric semi-conductors beyond the onset of current saturation is described. The procedure uses a wave equation derived from the well known formula for electron mobility of Feynman, Hellwarth, Iddings and Platzman in which the lattice coordinates have been removed. The zero order state in the procedure is that of electrons pursuing a constant velocity path, (infinite effective mass approximation), the velocity being taken at a phase velocity of acoustic shear modes. To the next order electrons are bound by and oscillate in a quasi-potential, which itself travels at the shear wave velocity. Electrons in a single well act coherently in producing a potential strong enough to bind them despite their Coulomb repulsion. We estimate the number of electrons bunched into a single droplet, as well as the electric field to sustain this motion, i.e. the field in the high field domain.     

Electron transport in disordered semiconductors

The density matrix of an electron in an amorphous semiconductor, written as a double path integral, is averaged over random disorder. For small disorder the golden rule result is recovered. When the mean disorder energy approaches k_BT, the electronic mobility goes to zero signalling disorder induced localization.     

<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.     

Two component solution for an alternative order parameter in HTSC

In an early study the BCS wave function was generalized to include the motion of the center-of-mass of Cooper pairs. An alternative order parameter can be defined on the basis of this motion. In later work, when in copper oxides Bloch orbitals replaced free electrons, nodes were found in the vector space of the Fourier representation of the order parameter. Here that Fourier representation has suggested that the parameter consists of two components, a long wave lengths part which does not contain nodes, a short wave length part which does. The former component is real, and applies deep inside the superconductor, the latter, which is imaginary, in the boundary region. Further, the imaginary component has odd symmetry about the nodal axis. There results an addition of about 0.93π to the relative phase of two adjacent sides of a square superconductor cut along appropriate crystal axis, and embedded in a normal metal.