11 research outputs found
Synthesis, characterization and AC conductivity studies of silver doped conducting polyaniline/graphene/SrTiO3 composites
No full textAlternating current conduction studies on polypyrrole-iron nanocomposite at room temperature
No full textSynthesis, characterization and DC conductivity studies of conducting polyaniline/PVA/Fly ash polymer composites
No full textElectromagnetic shielding effectiveness studies on polyaniline/CSA-WO3 composites at KU band frequencies
No full textEffect of polyvinylpyrrolidone content on alternating current conductivity of polyaniline
No full textSynthesis and characterization of novel imidazoquinoline based 2-azetidinones as potent antimicrobial and anticancer agents
No full textAbstractA new series of N-substituted azetidinones (9a–h) synthesized by condensation of 4-arylidene hydrazino 1-isobutyl-1H-imidazo[4,5-c]quinolines (8a–h) with chloroacetyl chloride afforded 4-arylazetidin-2-ones (9a–h). The synthesized compounds were characterized by 1H NMR, 13C NMR, mass spectral and elemental analyses. All synthesized compounds were screened for their in vitro antimicrobial and anticancer activities. The hydrazone derivatives (8a–h) showed good antibacterial activity. Compounds 9a and 9b exhibited good anticancer activity. In a molecular docking study compounds 9a and 9b showed minimum binding energy and good affinity towards the active pocket. Thus, are believed to be good inhibitors of β-tubulin
Structural, crystallographic, Hirshfeld surface, thermal and antimicrobial evaluation of new sulfonyl hydrazones
No full textSynthesis, characterization, CT-DNA binding and docking studies of novel selenated ligands and their palladium complexes
No full textA novel selenated Schiff base (S)-(LH)-H-1 has been synthesized from (2S)-1-(benzylselanyl)-3-phenylpropan-2-amine which upon reduction formed a reduced Schiff base (S)-(LH)-H-2. Palladium (II) complexes (S)-1 and (S)-2 of ligands (S)-(LH)-H-1 and (S)-(LH)-H-2 respectively were successfully synthesized. The structures of all four compounds were thoroughly identified by analytical and various spectroscopic techniques. The absolute molecular structures of the above two complexes were further confirmed by single crystal X-ray diffraction. Both (S)-(LH)-H-1 and (S)-(LH)-H-2 coordinated as monobasic ((S)-L1-2), chelating, tridentate (Se,N,O-) ligands resulting in the complexes of composition (S)-PdCl(L-1/2)] (S)-1/2]. In the crystals of complexes (S)-1 and (S)-2, there were moderate to strong SeMIDLINE HORIZONTAL ELLIPSISO, CHMIDLINE HORIZONTAL ELLIPSISCl and CHMIDLINE HORIZONTAL ELLIPSISO types of intermolecular secondary interactions. CT-DNA binding activity of these selenium-containing ligands and their palladium complexes bearing a Pd-Se bond have been evaluated for the first time by performing electronic absorption titration and fluorescence emission quenching using CT-DNA-EB and viscometric experiments. These ligands and complexes exhibited remarkable DNA binding activity as shown by their intrinsic DNA binding constants (K-b) and Stern-Volmer constants (K-sv) in the ranges 5.2-9.9 x 10(4) and 3.6-4.7 x 10(4), respectively. The viscosity of CT-DNA decreases with increasing concentration of these compounds. The results of the DNA-binding studies revealed that all of the compounds interact with DNA at a minor groove which was further confirmed by molecular docking studies
SUCTION MEASUREMENTS AND WATER RETENTION IN UNSATURATED SOILS
No full textTechniques for testing unsaturated soils have been investigated by the author where the measurement and control of parameters were undertaken directly. Suction was measured and controlled with a new high suction tensiometer and water content through mass measurements with a balance. These techniques have been used for the determination of soil water retention curves and for the development of a suction . control system using air circulation and water injection. The techniques allow the soil to be subject to the same drying and wetting conditions that occur in nature and avoid the need for elevated air pressures, as are traditionally involved in testing using the axis translation technique. The performance of the new high suction tensiometer was evaluated, followed by its applications to soil testing. The tensiometer performance focused on the factors controlling cavitation, calibration in the negative pressure range and measurement. It was found that isotropic unloading is the most accurate technique for calibration in the negative range and that axis translation techniques can lead to errors. The research confirms high suction tensiometers are easy to use and versatile devices. Techniques were developed to measure and control suction and water content in unconfined and confined samples. Research on the unconfined samples focused on the procedures to obtain the soil water retention curve: discrete (soil dried or wetted in stages) and continuous (soil drying continuously). While both procedures were found not to influence the curves significantly, it is demonstrated that the continuous procedure is sensitive to factors such as the exposed surface area to drying or wetting and so should be used carefully. For confined conditions, wetting, drying, and water content measurement systems were developed. Wetting was based on the injection of water; drying was based on air circulation through a desiccant within a closed loop system. Water content was determined from the. difference between water injected and that adsorbed by the desiccant. This has been applied as part of a· double cell triaxial testing system that allows continuous determination of suction, water content and volume change. A challenge of such a system was imposing an air tight environment. The suitability of environmental scanning electron microscopy to observe unsaturated soils at the particle level was explored. The imaging of micron-sized materials at different relative humidities allowed a series of observations previously undocumented, among them: water menisci were visible, including their shape and interaction with surfaces; the contact angle between the air-water and water-solid interfaces was measurable.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Mechanisms of Shallow Rainfall-induced Landslides in Residual Soils in Humid Tropical Environments
No full textLandslide mechanisms and processes, particularly within the basal deformation region during failure, are poorly understood in the current knowledge. The aim of this research is to understand the initiation processes of shallow rainfall-triggered landslides under humid, tropical conditions. The major objectives are (1) to investigate the actual processes of rainfall-triggered landslides; and (2) to examine the relationship between the rates of pore water pressure increase and the rates of soil movement. Field sampling has been undertaken at two landslide sites on weathered volcanic slopes on Lantau Island, Hong Kong (22°N, 114°E). Reinflation tests have been conducted on the undisturbed soil samples using a triaxial stress path cell to replicate the field conditions during rainstorm events. Various rates of increasing pore water pressure have been designed with reference to the field monitoring data. Landslide initiation processes have been deduced by examining the relationship between the increasing pore water pressures and soil deformation. The results demonstrate that rainfall-induced landslide development on weathered slopes undergoes three stages with distinctive movement patterns towards failure. The key controlling mechanism appears to be plastic deformation. The varied velocities are dependent on the stress state (changes in the mean effective stress, under constant shear stress), the pore water pressure reinflation rate and soil permeability, stage 1 represents a perfectly plastic state below yield. Velocity remains low or at zero as the soil particles are strongly interlocked. The fluctuating to constant strain rates at stage 2 are primarily controlled by the reinflation rate and permeability after exceeding the yield state, with localised interparticle sliding. Rapid acceleration to failure occurs at stage 3, facilitated by the general remoulding process. The systematic movement patterns have also been observed in shallow rainfall- induced landslides in plastic soil materials. The steady-state behaviour could be a precursor for the acceleration to the final failure
