A volumetric and viscometric study of 4-aminobutyric acid in aqueous solutions of metformin hydrochloride at 308.15, 313.15 and 318.15 K

Density (r) and viscosity (h) measurements were performed for4-aminobutyric acid in 0.05, 0.10 and 0.15 M aqueous metformin hydrochloride at 308.15, 313.15 and 318.15 K. The measured values of density and viscosity were used to estimate some important parameters, such as the partial molal volume, Vf, the standard partial molal volume, Vf, the standard partial molal volume of transfer, DVf, the hydration number, nH, the second derivative of the infinite dilution of the standard partial molal volume with temperature ¶2Vf/¶T2, the viscosity B-coefficients, variation of B with temperature, dB/dT, the free energy of activation per mole of solvent Dm1* and solute Dm2* of the amino acid in a ternary system. These parameters were interpreted in terms of solute–solute and solute–solvent interactions and structure making/breaking ability of solutes in the given solution

Rice endophytes and their potential applications

Endophytic microbial communities in crop plants are beginning to be explored. These microbes are either carried through seeds or establish colonization in the plants from soil based on chemotaxis of root exudates. Variability and diversity of endophytic bacteria and fungi have been observed in rice plants in different plant parts and growth stages. Genotypic variations are observed between Indica and Japonica. Pseudomonas, Bacillus, Streptomyces, Azospirillum, Azotobacter are some of the dominating genera of bacteria in internal tissues of rice plants. These endophytes provide benefits such as tolerance to abiotic stresses, defense against pest and diseases, nutrient solubilization and mobility. In addition, many metabolites are characterized from the endophytes that are useful in other branches of biotechnology including bioremediation. Complete characterization of microbiome of rice plants under various soil agro-climatic zones and understanding their population dynamics, co-occurrence and networking will help in identifying useful strains for developing new biofertilizers, plant growth promoting microbes and biopesticides

Fabrication and modelling of porous silicon schottky diode

Advisors: Michael J. Haji-Sheikh.Committee members: Mansour Tahernezhadi; Donald S. Zinger.Includes illustrations.Includes bibliographical references.The thesis work primarily focuses on fabrication and modelling of Schottky Diode formed using porous silicon. The wafer used for this is silicon coated with silicon nitride on both sides. A photoresist is deposited on the front side of the wafer using spin coating technique and silicon nitride that is coated on the back side is etched off using dry chemical etching process. A photomask is designed using AutoCAD software which helps open windows on the front side of the wafer. Windows are opened on the front side using positive photoresist technique. This technique enables the portion of the wafer that is exposed to UV light more soluble in the developer solution making the unexposed portion opaque or insoluble. Silicon nitride is etched off on the front side where the windows are opened using similar dry chemical etching process. After coating photoresist on the front side, silicon nitride on the backside is etched completely. Silicon nitride thickness before and after etching has been recorded. The wafer is then diced into smaller samples and allowed to grow pores. Electrochemical etching process with the electrolyte HF:Ethanol in the ratio of 1:3 is used for porous silicon formation. The samples are then coated with Chrome/Gold contact on front and backside and are examined under Scanning Electron Microscope (SEM). The device, when exposed to light, exhibits schottky diode characteristics. The forward and reverse diode characteristics have been tested.M.S. (Master of Science

Friction Stir Welding of Dissimilar Butt Joints with Novel Joint Geometry

In this study, 1 mm thin sheets of AA 6061 and steel were welded by friction stir, with new joint geometry. Conventional friction stir welding develops high distortion to the specimen, particularly when the thickness is very small. In this process, friction stir welding is carried out by a tool without probe and with new joint geometry. Contrary to the conventional friction stir welding, where various tool profiles are used to obtain successful joints, the present study of investigation focused on developing a profile in the sheet metal edges to be joined. The aluminium sheet was positioned on the contoured steel sheet. Rotating tool with tilt angle was made to progress into the top sheet. Frictional heat plasticized the upper blank and the edges of the aluminium sheet were forged and extruded into the steel contour. The welding between steel and aluminium was due to a coalescence of the two materials and clamping effect was provided by the contour in the steel sheet. Tensile test was conducted to evaluate the quality of the welding along with macro and micro metallographic investigations. Further to this, scanning electron microscopy with energy dispersive X-ray and X-ray diffraction analysis have been done to understand the presence of intermetallics at the weld nugget. Tensile strength of 122.22 MPa was achieved. Intermetallics of Mg₂Si, MnAl₆ and FeAl₆, Al₅Fe₂ was found as dominant compound at the interface. Welding of thin sheets is enhanced by form clamping and chemical diffusion bonding

DNA-binding, catalytic oxidation, CC coupling reactions and antibacterial activities of binuclear Ru(II) thiosemicarbazone complexes: Synthesis and spectral characterization

AbstractNew hexa-coordinated binuclear Ru(II) thiosemicarbazone complexes of the type {[(B)(EPh3)(CO)ClRu]2L} (where, E=P or As; B=PPh3 or AsPh3 or pyridine; L=mononucleating NS donor of N-substituted thiosemicarbazones) have been synthesized and characterized by elemental analysis, FT-IR, UV–vis and 31P{1H} NMR cyclic voltammetric studies. The DNA-binding studies of Ru(II) complexes with calf thymus DNA (CT-DNA) were investigated by UV–vis, viscosity measurements, gel-electrophoresis and fluorescence spectroscopy. The new complexes have been used as catalysts in CC coupling reaction and in the oxidation of alcohols to their corresponding carbonyl compounds by using NMO as co-oxidant and molecular oxygen (O2) atmosphere at ambient temperature. Further, the new binucleating thiosemicarbazone ligands and their Ru(II) complexes were also screened for their antibacterial activity against Klebsiella pneumoniae, Shigella sp., Micrococcus luteus, Escherichia coli and Salmonella typhi. From this study, it was found out that the activity of the complexes almost reaches the effectiveness of the conventional bacteriocide

Synthesis, spectral, dna binding and cleavage properties of ruthenium(II) Schiff base complexes containing PPh3/AsPh3 as co-ligands

A dihydroxybenzaldehyde Schiff base ligands (L1-L3) and its ruthenium(II) complexes, have been synthesized and characterized on the basis of elemental analysis, 1H, 13C, 31P NMR, mass spectra, UV-vis and IR spectra. The binding of ruthenium(II) complexes have been investigated by UV-vis absorption spectroscopy. The experiment reveals that all the compounds can bind to DNA through an electrostatic mode and intrinsic binding constant (Kb) has been estimated under similar set of experimental conditions. Absorption spectral study indicate that the ruthenium(II) complexes has intrinsic binding constant in the range of 1.6-8.6 X 104 M-1. The complex [Ru(CO)(PPh3)2(L3)] bind more strongly than that of the other complexes. In addition, DNA cleavage property were tested for all ruthenium(II) complexes

Aerosol Black Carbon Measurement at High Altitude Western Ghats Location of Ooty, Tamil Nadu

The aerosol Black Carbon (BC) are particles formed from the incomplete combustion of fossil fuel and biomass combustion which was collected from high altitude location in Western Ghats, Ooty, Tamil Nadu using Aethalometer Instrument (model AE-31 of Magee Scientific, USA) during 2017. The monthly averaged BC concentration shows highest value of 1.88 ± 0.44 µg m-3 during April with the annual mean of 0.83 ± 0.20 µg m-3. The diurnal variation shows higher seasonality especially in winter and summer with highest peak in 17:00 to 22:00 hr. The aerosol optical depth derived from MERRA 2 model showed annual mean of 0.29 and it is in line with BC concentration. The results showed that the concentrations are varying within a day, month and season depends on the local meteorological conditions