Diffusion of Gases in Amylose Acetate

Diffusion of helium, oxygen, nitrogen and carbondioxide in amylose acetate in the temperature range 30°–60°C has been reported. The Arrhenius parameters have been evaluated and the solubility of the gases in the polymer has been discussed in terms of condensing tendency of the gases studied.     

Studies in mixed aqueous media. II. Acidity Constants of Simple and Chloro-o-toluidinium Ions in the system dioxane–water

Acidity constants of 3-, 4- and 5-chloro-o-toluidinium ions have been measured at 25° in aqueous dioxane media containing 20, 45, 70 and 72 wt.% of 1.4-dioxane by pH metry. The necessary correction factors to convert pH meter readings into stoichiometric pH have been evaluated. The relation between the strength of anilinium ions and various solvent properties has been discussed. A HAMMETT type relation has been developed for correlating the acid strength of these disubstituted anilinium ions with HAMMETT 's structural parameters.     

On the Stiffness of Amylosic Chains

The solution behaviour of amylosic chains has been reviewed in light of the stiffness parameter ρ. The stiffness parameter is reevaluated for three probable conformations of amylose in solution according to Burchard. It is shown that the boat conformations explain the flexibility of amylosic chains which is consistent with their solution behaviour.     

2-mercaptothiazoline as corrosion inhibitor for copper in acidic media

The influence of 2-mercaptothiazoline as a corrosion inhibitor for copper in acetic acid, monochloroacetic acid, dichloroacetic acid and trichloroacetic acid solutions has been investigated. The inhibitive power of 2-mercaptothiazoline among above stated acids is in the following order: trichloroacetic acid > dichloroacetic acid > monochloroacetic acid > acetic acid.The inhibition afforded by 2-mercaptothiazoline may be attributed to its chelate-forming tendency towards copper ions. The percentage efficiency obtained by weight loss method is correlated with the Tafel slope. The reaction is cathodically controlled.     

Electronic property of photosensitive film on copper in solutions of iodine in chloroform

Photosensitive films formed on electrolytic copper plate by treatment with iodine solution in chloroform, give a print of the trade mark of the container. The electrical property of the film was studied. Current produced between two treated surfaces of the plate, one exposed to sunlight and the other unexposed, was plotted against time of exposure; a change in polarity was observed. The mechanism of photosensitive film formation and the change in polarity are discussed.     

Pre-qualification of brazed plasma facing components of divertor target elements for ITER like tokamak application

Qualification of tungsten (W) and graphite (C) based brazed plasma facing components (PFCs) is an important R&D area in fusion research. Pre-qualification tests for brazed joints between W–CuCrZr and C–CuCrZr using NDT (IR thermography and ultrasonic test) and thermal fatigue test are attempted. Mockups having good quality brazed joints of W and C based PFCs were identified using NDT. Subsequently, thermal fatigue test was performed on the identified mockups. All brazed tiles of W based PFC mockups could withstand thermal fatigue test, however, few tiles of C based PFC mockup were found detached. Thermal analyses of mockups are performed using finite element analysis (ANSYS) software to simulate the thermal hydraulic condition with 10 MW/m² uniform heat flux. Details about experimental and computational work are presented here.     

Methyldichloroborane evidenced as an intermediate in the chemical vapour deposition synthesis of boron carbide

The most recent ceramic-matrix composites (CMC) considered for long-life applications as thermostructural parts in aerospace propulsion contain, among others, boron-rich phases like boron carbide. This compound is prepared by thermal Chemical Vapour Infiltration (CVI), starting from precursors like boron halides and hydrocarbons. We present a study aiming at a precise knowledge of the gas-phase composition in a hot-zone LPCVD reactor fed with BCl3, CH4 and H2, which combines experimental and theoretical approaches. This work has brought strong evidences of the presence of Methydichloroborane (MDB, BCl2CH3) in the process. It is demonstrated that this intermediate, the presence of which had never been formally proved before, appears for processing temperatures slightly lower than the deposition temperature of boron carbide. The study features quantum chemical computations, which provide several pieces of information like thermochemical and kinetic data, as well as vibration and rotation frequencies, reaction kinetics computations, and experimental gas-phase characterization of several species by FTIR, for several processing parameter sets. The main results are presented, and the place of MDB in the reaction scheme is discussed.