Radiation induced polymerisation of trioxane: A study of the effects of variables

Polymerisation of trioxane in the solid state induced by γ-radiation is mainly affected by three variables: radiation dose, post-polymerisation temperature and its duration. In order to optimise the process parameters and study the effects and interactions of these three variables on the conversion of trioxane to polyacetal investigations were carried out by a series of statistically designed experiments. The relationship between the variables and yield was correlated by a least square fit polynomial equation. Applying this relationship, contours of yields were plotted against the variables in the range of interest. The effects of these process variables and the optimum conditions are discussed.     

Permeation of benzene through liquid surfactant membranes

The effect of time on the permeation of benzene through aqueous surfactant membranes formed with two non-ionic surfactants has been studied on a batch scale under two different conditions of surfactant concentration and hydrocarbon: water ratio in the emulsions. The data have been correlated by an equation based on Casamatta's model of hydrocarbon permeation from an emulsion drop. The results indicate that the correlation can be used to treat the data until the onset of membrane rupture. The membrane thickness depends on the hydrocarbon: water ratio in the emulsion, and varies from about 1.57 to 5.10 μm.     

Magnetically Separable Copper Ferrite Nanoparticles‐Catalyzed Synthesis of Diaryl,Alkyl/Aryl Sulfones from Arylsulfinic Acid Salts and Organohalides/Boronic Acids

A recyclable, inexpensive, non‐toxic and environmentally benign catalytic system comprised of magnetically separable copper ferrite (CuFe₂O₄) nanoparticles has been developed for the synthesis of diaryl, alkyl/aryl sulfones. Arylsulfinic acid salts are coupled with various alkyl/aryl halides/boronic acids to afford the corresponding diaryl, alkyl/aryl sulfones in good to excellent yields under the identical catalytic system. A wide range of functional group tolerance, with facile recovery of the catalyst by application of an external magnetic field, and consistently high catalytic efficiency for five consecutive cycles render the protocol operationally attractive.

     

Free Vibration Analysis of Thin Circular Cylindrical Shell with Closure Using Finite Element Method

Vibration analysis of a thin circular cylindrical shell with closure is conducted using finite element method (FEM). Theoretically, shell vibrates in different axial modes, m; circumferential modes, n; and any of their combinations with corresponding modal frequencies. The present FEM results are verified by the results reported in the literature using various shell theories. The eigenvalues of the shell are extracted using block Lanczos and subspace iteration methods, in order to investigate their computational efficacy. Further, the effect of adding various types of closures at one end of the circular cylindrical shell such as flat, cone, and dome, on the modal frequencies are investigated. The two aspect ratios (length to radius ratio) of shell with closure, broad, and slender are considered for this study. The effect of the ratio of the thickness of the closure to the thickness of shell wall on the frequency is also investigated. For the shell with the closure, the vibration modes can be cylinder, closure, or combined cylinder and closure. The modal frequency of the cylindrical shell is significantly affected by the closure. The lowest frequency is observed in the flat type of closure in both the broad and slender cylindrical shells in comparison to the non-closure, dome, and cone type of the closures.     

SOLUBILISED WAXES AND THEIR INFLUENCE ON THE FLOW PROPERTIES OF LUBE OIL BASE STOCKS

The physico-chemical properties of Lubricating oil base stocks (LOBS) are generally influenced by the type/nature and concentration of solubilised waxes present in them. Detailed composition of the solubilised waxes, saturates and aromatics present in LOBS and its distillate fractions has been sludied. Further the influence of these solubilised waxes and as well of saturates/aromatics on the flow properties particularly pour point, viscosity and viscosity temperature relationship of LOBS sample and its distillate fractions have been investigated. The response of a commercial pour point depressant additive with varying composition of solubilised waxes in lube oil base stock sample has also been studied.     

Using Holographic Microscopy To Measure the Effect of Confinement on Crowding Agents in Lipid Vesicles

The hydrodynamic effects of macromolecular crowding inside cells are often studied in vitro by using polymers as crowding agents. Confinement of polymers inside cell-sized droplets has been shown to affect the diffusion of small molecules. Here we develop a method, based on digital holographic microscopy, to measure the diffusion of polystyrene microspheres that are confined within lipid vesicles containing a high concentration of solute. We apply the method to three solutes of varying complexity: sucrose, dextran, and PEG, prepared at ∼7 % (w/w). We find that diffusion inside and outside the vesicles is the same when the solute is sucrose or dextran that is prepared below the critical overlap concentration. For poly(ethylene glycol), which is present at a concentration higher than the critical overlap concentration, the diffusion of microspheres inside vesicles is slower, hinting at the potential effects of confinement on crowding agents.