http://hdl.handle.net/2289/149 Search the Channel search http://dspace.rri.res.in:8080/jspui/simple-search http://hdl.handle.net/2289/3899 Title: Experimental studies of the transient fluctuation theorem using liquid crystals<br/><br/>Authors: Datta, Soma; Roy, Arun<br/><br/>Abstract: In a thermodynamical process, the dissipation or production of entropy can only be positive or zero, according to the second law of thermodynamics. However, the laws of thermodynamics are applicable to large systems in the thermodynamic limit. Recently a fluctuation theorem, known as the transient fluctuation theorem (TFT), which generalizes the second law of thermodynamics to small systems has been proposed. This theorem has been tested in small systems such as a colloidal particle in an optical trap. We report for the first time an analogous experimental study of TFT in a spatially extended system using liquid crystals.<br/><br/>Description: Open Access Tue, 28 Apr 2009 22:58:59 GMT http://hdl.handle.net/2289/3898 Title: Kinetics of trans-cis isomerization in azobenzene dimers at an air-water interface<br/><br/>Authors: Kumar, Bharat; Suresh, K. A.<br/><br/>Abstract: We have studied the kinetics of trans to cis isomerization under the illumination of ultraviolet light, in the Langmuir monolayer of mesogenic azobenzene dimer, bis-[5-(4[prime]-n-dodecyloxy benzoyloxy)-2-(4[double-prime]-methylphenylazo)phenyl] adipate, at an air-water interface. We find that the trans to cis isomerization reaction of the molecules in the monolayer shows deviation from the first-order kinetics unlike those reported on Langmuir monolayers of azobenzene molecules. We attribute the deviation from first-order kinetics to the simultaneous photoisomerization of trans isomers to form cis isomers and the reverse thermal isomerization of cis isomers to form trans isomers. Our analysis of the rate of change of mole fraction of trans isomers to form cis isomers indicates a first-order kinetics for trans to cis photoisomerization reaction and a second-order kinetics for cis to trans thermal isomerization reaction. This second-order kinetics mechanism is similar to the Lindemann-Hinshelwood mechanism for the unimolecular reactions at low concentration of reactants. The formation of the activated cis isomer by collisions is a slow process as compared to the decay of the activated cis isomer to trans isomer in the liquid expanded phase. This results in the second-order kinetics for the thermal isomerization of cis isomers.<br/><br/>Description: Open Access Sun, 02 Aug 2009 22:58:59 GMT http://hdl.handle.net/2289/3897 Title: Playing with discs<br/><br/>Authors: Kumar, Sandeep<br/><br/>Abstract: The hierarchical self-assembly of disc-shaped molecules leads to the formation of discotic liquid crystals. These intriguing materials are of fundamental importance not only as models for the study of energy and charge migration in self-organised systems, but also as functional materials for various device applications. This has fostered numerous developments in this field. In this article, we have summarised the author's and the collaborators' research work on discotic liquid crystals.<br/><br/>Description: Restricted Access. Fri, 29 May 2009 22:58:59 GMT http://hdl.handle.net/2289/3896 Title: Electrochemically grown mesoporous gold film as high surface area material for electro-oxidation of alcohol in alkaline medium<br/><br/>Authors: Nagaraju, D. H.; Lakshminarayanan, V.<br/><br/>Abstract: We show here that, by using a simple template free electrodeposition process, it is possible to obtain a dense mesoporous gold film on a metal surface possessing good adhesion, large surface area, and mechanical integrity. The measured electrochemically active true surface area of the film prepared by this method is the highest reported to date for a mesoporous gold surface. The real surface area also increases with increasing time of deposition, showing its potential for scalability. The mesoporous surface was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and cyclic voltammetry (CV). The surface characterization studies confirm the formation of porous film constituted of Au nanoparticles. We find, from the CV studies, that the mesoporous gold surface prepared using the method described here shows excellent catalytic activity for alcohol electro-oxidation in an alkaline medium.<br/><br/>Description: Restricted Access. Mon, 27 Jul 2009 22:58:59 GMT