Modulation of agonist and antagonist interactions in serotonin 1A receptors by alcohols

The serotonin type IA (5-HT1A) receptors are members of a superfamily of seven transmembrane domain receptors that couple to GTP binding regulatory proteins (G-proteins). Serotonergic signalling has been shown to play an important role in alcohol tolerance and dependence. We have studied the effects of alcohols on ligand (agonist and antagonist) binding to bovine hippocampal 5-HT1A receptor in native as well as solubilized membranes. Our results show that alcohols inhibit the specific binding of the agonist OH-DPAT and the antagonist p-MPPF to 5-HT1A receptors in a concentration-dependent manner.     

Comparative inhibitory properties of some Indian medicinal plant extracts against photosensitization-induced lipid damage

The protective activities of Emblica officinalis, Terminalia bellerica and Terminalia chebula ethanol extracts against photosensitization-induced oxidation of rat liver mitochondrial lipid were assessed. All the extracts could effectively prevent lipid peroxidation, as assessed by measuring thiobarbituric acid-reactive substrates, lipid hydroperoxide, conjugated diene and 4-hydroxynonenal. The E. officinalis extract was the most potent, revealing its superior ability to scavenge ¹O₂. The extracts also afforded excellent protection against iron-mediated lipid peroxidation that might also be useful in reducing photo-induced iron toxicity. The activities of the extracts were primarily due to their constituent phenolics.     

The evolution of microstructure in the undercooled Zn-Sn entrained droplets

The existence of a metastable miscibility gap has been indicated from the metastable phase diagram of the Zn-Sn system calculated using regular solution and Krupkowski's models. To validate this phenomenon experimentally, the entrained droplet technique was used to achieve high undercooling and to access the metastable regions. The microstructural analysis confirms the miscibility gap and the associated monotectic reaction. Evidence is also presented for a possible massive solidification of the undercooled melt. J.P.N. Srivastava, formerly Undergraduate Student with the Department of Metallurgy, Indian Institute of Science     

Electrical conductivity and luminescence of 9-chloro-10,10′-bis-(dichloromethyleno)-(9′H)-10,10′-dihydro-9,9′-bianthryl (CDDB)

The absorption and fluorescenc of 9-chloro-10,10′-bis-(dichloromethyleno)-(9′H)-10,10′-dihydro-9,9′-bianthryl (CDDB) has been studied in polar and nonpolar solvents and also in microcrystal. In polar solvents CDDB emits from two molecular forms, the normal charge transfer form (locally excited, LE form) and the solvent-induced twisted intramolecular charge transfer (TICT) form. Electrically, CDDB possesses semiconducting property with conductivity approximately 10⁻⁹ S cm⁻¹ and this conductivity further increases to 10⁻⁷ S cm⁻¹ on photoexcitation. Intramolecular charge transfer by hopping mechanism is assumed to be the main process for controlling activation energy and electronic conduction.     

A new look into the acquisition properties of a second-orderdigital phase locked loop

With the help of real-time numerical simulation results, the acquisition properties of a second-order ZC₁-DPLL are investigated. Besides confirming the sensitivity of the system dynamics to the initial values of the state variables, it predicts qualitatively the maximum possible frequency acquisition range (FAR) of the system, and obtains the values of the maximum FAR for systems with different design parameters. The effect of jitter on the loop dynamics has also been considered     

A generalized approach to steady-state analysis of a current-sourceinverter with induction motor load including commutation overlap

A generalized state-space approach is presented for the steady-state commutation analysis of an autosequential commuted current-source inverter-fed induction motor drive covering all possible modes of operation using a digital computer. The analysis adopts the basic per-phase equivalent circuit for the induction motor model, includes the effect of DC link filter impedance and the variation of back EMF during the commutation interval, and extends the inverter model to cover the complex commutation overlap mode occurring during high frequency operation. A digital computer program is evolved, to identify automatically the relevant sets of equations applicable to a particular mode from a generalized set of equations and to solve them