Electrical performance of conducting polymer (SPAN) grown on GaAs with different substrate orientations

This article reports the effect of n-type GaAs substrate orientation, namely (100), (311)A and (311)B, on the electrical properties of sulfonated polyaniline (SPAN)/GaAs heterojunction devices. In addition, the inhomogeneity of the interface between various GaAs substrates and SPAN is investigated in terms of barrier height and ideality factor by performing I–V measurements at different temperatures (20–420K). The I–V results indicate that the value of the rectification ratio (IF/IR) at 0.5V is higher for SPAN/(311)B GaAs samples than for SPAN/(100) GaAs and SPAN/(311)A GaAs samples. Moreover, the barrier height decreases and the ideality factor increases with decreasing temperature for all three heterostructure devices. The high value of mean barrier ˚¯ b of SPAN/(311)B (calculated from the plots of ˚b0 as a function of 1/2kT) confirms that the GaAs substrate orientation results in an increase of barrier homogeneities. Furthermore,the C-V characteristics were obtained at room temperature. The C-V measurements showed that the carrier distributions at the interface and away from the interface in high index (311) GaAs orientations are more uniform and have better barrier homogeneity than those grown on the conventional (100) GaAs substrates

Properties of two benzodiazepine binding sites in spinal cord

Two types of benzodiazepine receptors were demonstrated in spinal cord. Binding to one of these sites (neuronal) was sensitive to the centrally active benzodiazepine, clonazepam, and binding was enhanced both by chloride and GABA. The second site was sensitive to 7-chloro-1,3-dihydro-1-methyl-5-(p-chlorophenyl) 2H-1,4-benzodiazepine-2-one (R05-4864) and thus is similar to the site characteristic of non-neuronal tissue. Binding to the neuronal site was inhibited by the putative glycine antagonist, strychnine, both in spinal cord and brain. This inhibition may account for the reported anti-GABAergic properties of strychnine and does not appear to be related to the glycine receptor

Peripheral benzodiazepine binding sites in kidney: modifications by diabetes insipidus

Using [3H] diazepam as ligand, it is possible to distinguish neuronal binding sites from those present on glial elements and in peripheral tissues (non-neuronal). The function of the 'non-neuronal' binding sites is still obscure. Preliminary data showed a distribution of [3H] diazepam binding sites in kidney that could suggest a localization along the renal tubules. This is the site at which a renal peptide, arginine-vasopressin (AVP) is supposed to act. In an attempt to examine the function of these 'non-neuronal' sites, we studied the [3H] diazepam binding in kidney of Brattleboro rats which lack AVP and present the symptoms of diabetes insipidus. The homozygous Brattleboro rats showed an increase in the apparent number of benzodiazepine binding sites (Bmax) compared to Long-Evans control rats. Replacement of AVP in these animals results in a reversal of the electrolyte alterations of diabetes insipidus and in an increase of the affinity of the [3H] diazepam binding. These findings may indicate a possible relationship between benzodiazepine binding sites and vasopressin action in kidney and may support receptor function of these 'non-neuronal' binding sites