Kuvempu University

About: Kuvempu University is a education organization based out in Shimoga, India. It is known for research contribution in the topics: Cyclic voltammetry & Carbon paste electrode. The organization has 1575 authors who have published 2210 publications receiving 39755 citations. The organization is also known as: KU.

Effect of method of preparation and process variables on controlled release of insoluble drug from chitosan microspheres

Abstract: An inexpensive and simple method was adopted for the preparation of chitosan microspheres, crosslinked with glutaraldehyde (GA), for the controlled release of an insoluble drug-ibuprofen, which is a commonly used NSAID (non-steroidal anti-inflammatory drug). The chitosan microspheres were prepared by different methods and varying the process conditions such as rate of stirring, concentration of crosslinking agent, and drug:polymer ratio in order to optimize these process variables on microsphere size, size distribution, degree of swelling, drug entrapment efficiency, and release rates. The absence of any chemical interaction between drug, polymer, and the crosslinking agent was confirmed by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and thermogravimetric analyses (TGA) techniques. The microspheres were characterized by optical microscopy, which indicated that the particles were in the size range of 30–200 µm and scanning electron microscopy (SEM) studies revealed a smooth surface and spherical shape of microspheres. The microsphere size/size distributions were increased with the decreased stirring rates as well as GA concentration in the suspension medium. Decreasing the concentration of crosslinker increased the swelling ratio whereas extended crosslinking exhibited lowered entrapment efficiency. The in vitro drug release was controlled and extended up to 10 hr. Copyright © 2007 John Wiley & Sons, Ltd.

Studies on the preparation and properties of electroless Ni-W-P alloy coatings and its nano-MoS 2 composite

Abstract: The electroless Ni–W–P ternary alloy and its MoS2 composite films were successfully obtained on low-carbon steel by the electroless plating technique The sodium tungstate concentration in the bath was varied to obtain Ni–W–P deposits containing various W and P contents Ni–W–P–MoS2 composite was obtained with a suitable concentration of sodium tungstate in the plating bath These deposits were characterized via x-ray diffraction (XRD), scanning electron microscopy and energy dispersive XRD spectroscopy studies The corrosion behavior was investigated via potentiodynamic polarization and electrochemical impedance spectroscopy studies in a 35 wt% NaCl solution An increase in codeposition of the alloying metal tungsten changed the structure and morphology of the deposits and enhanced the corrosion resistance Mechanical properties such as microhardness and friction coefficients were evaluated Ni–W–P deposits with increasing amounts of tungsten metal were found to possess higher friction coefficients The microhardness was greatly improved with increasing codeposition of tungsten metal in the alloy The incorporation of MoS2 nanoparticles into Ni–W–P alloy coatings strongly influenced in reducing the corrosion and friction

A rapid and modified approach for C-7 amination and amidation of 4-methyl-7-nonafluorobutylsulfonyloxy coumarins under microwave irradiation

Abstract: A facile, efficient and reliable access for the synthesis of an array of 4-methyl-7-(alkyl/aryl/heteroaryl) amino and amido coumarins has been developed by treating 4-methyl-7-nonafluorobutylsulfonyloxy coumarin with various amines and pyridones in presence of a catalyst combination of Pd2(dba)3/xantphos under microwave irradiation. Nonaflates coupled efficiently to give the diaryl amines in acceptable to excellent yields whereas the corresponding triflate was unstable, yielding the detriflated product as well as the hydrolyzed product as competing side products along with the desired product. The wide bite angle (108°) of xantphos, employment of Cs2CO3 as a mild base and the utilization of TBAF·3H2O as an additive proved to be key for success of the reaction.

Fabrication and electrochemical characterization of Zn–halloysite nanotubes composite coatings

Abstract: Zinc–halloysite nanotube (HNT) composite coatings through electrodeposition technique were successfully fabricated on mild steel substrate As a comparison, pure zinc coating was also prepared The composites were deposited in the presence of the surfactants cetyltriammonium bromide (CTAB) and sodium lauryl sulfate (SLS) The effect of the addition of nanoparticles and surfactants on the deposition, crystal structure, texture, surface morphology and electrochemical corrosion behavior were investigated For the characterization of the electrodeposits, techniques such as X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis were used Both the additives HNTs and surfactants polarize the reduction process and thus influence the deposition process, surface nature and electrochemical properties Electrochemical experiments, such as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies, carried out in 35% NaCl solution show higher corrosion resistance by HNT incorporated coating, which was fabricated in the presence of CTAB Microhardness of the deposits was evaluated and the composite with higher incorporation of nanoparticles in the presence of CTAB exhibited the highest value