Abstract: Calcium oxalate monohydrate (COM) is the primary constituent of the majority of stones formed in the urinary tract. Mechanical properties of renal calculi dictate how a stone interact and disintegrate with mechanical forces produced by shock wave and laser lithotripsy techniques. Tensile stresses may be more effective in some instances in disrupting material because most materials are weaker in tension than compression. Urinary stone containing COM as a major component was subjected to tensile, flexural and compressive strength studies in order to understand its mechanical properties in vitro. The calculated tensile breaking strength for the urinary stone from three tests varies from 0.57 MNm-2 to 1.52 MNm-2. The flexural strength and the flexural modulus of the urinary stone were calculated as 5.17 MNm-2 and 2.22 GNm-2 respectively while the observed compressive strength was 6.11 MNm-2. The chemical composition and the crystalline nature of the stone were verified using Fourier Transform Infrared spectroscopy and X-ray diffraction.
Abstract: Calcium oxalate is the most significant component of urinary stones, usually in its monohydrate form. The mechanisms for the formation of calcium oxalate urinary stones are still not understood, though it is thought that organic macromolecules play a significant role. Calcium oxalate monohydrate (COM) urinary stone was subjected to dielectric studies in order to understand the formation and growth of the renal stones in vivo and use them to help in the treatment procedures for more effective stone fragmentation. The chemical composition and the crystalline nature were verified using Fourier Transform Infrared spectroscopy, X-ray diffraction and thermal analysis. The dielectric parameters for the COM renal stone namely, capacitance, dielectric loss coefficient, impedance, and resistance were measured at room temperature and hence the dielectric constant and the alternating current conductivity were calculated in the frequency range 200 Hz to 5 MHz. The measured values and the dielectric constant showed systematic variations up to 10 kHz. The alternating current conductivity was almost constant up to 2.0 kHz and then showed systematic increase at around 100 kHz and reaches a maximum value at around 5 MHz. The results may be used in further studies of renal stones about their formation and growth.
Abstract: Kidney stones or renal calculi or Nephrolithiasis is a common health problem in both developed and developing nations [1,2]. Analysis of the chemical and physical properties of renal calculi helps in preventing their formation and treatment. In this study, we evaluated the hardness of water used for drinking purposes, in an attempt to correlate water hardness with an increased incidence of stone formation. Identifying risk factors help to develop a preventive strategy to reduce the risk of renal calculi formation. The incidence of kidney stone formation in Vellore district was correlated with the hardness of water samples taken from different areas in Vellore. The study can be employed at a larger demographic level for effective and economic monitoring of the risk of kidney stone formation.
Abstract: We have successfully demonstrated the effect of Gamma-irradiation on Polyacrylonitrile (PAN) gel in terms of admittance (Y), Susceptance (B) and Conductance (G). The trend of Y and B decreases by 297 microSec and 138 microSec respectively and conductance (G) increases by 100 μS. Electrical mechanism associated with microstructure of PAN gel under external DC bias potential is the novelty of this work. External field stimuli responded due to delocalization of charge carriers. These properties are important as novel electronic material.
Abstract: AA6061 alloy is most widely used in aircraft fittings, marines fitting and automobile industries. This alloy can be joined by fusion welding process like Gas Tungsten Arc Welding (GTAW). An important metallurgical difficulty in arc welding of this alloy is hot cracking. As the name indicates, this kind of cracking occurs while the metal is still hot. It usually occurs in the fusion zone during solidification. The main aim of this work is to investigate the effect of vibratory treatment on hot cracking of AA6061 alloy. Houldcroft hot cracking test is used to determine the hot cracking tendency. Weld bead was made on AA6061 alloy specimen in the presence and absence of vibratory treatment. Vibratory treatment was carried out in the frequency range of 250 Hz to 900 Hz. Weldments made with and without vibratory treatment were compared using hot cracking tests. Test results show that by applying vibratory treatment, hot cracking can be largely controlled in AA6061 alloy.
Abstract: A new solid-state pseudo binary system BiI3_-Ag2SO4 involving bismuth triiodide (BiI3) and a silver oxysalt namely silver sulphate (Ag2SO4) has been prepared using rapid melt-quenching technique. AC conductivity studies have been carried out on the nine different samples of the (BiI3)x –- (Ag2SO4)(1-x) system with compositions corresponding to x=0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8 and 0.9 mole fraction at temperatures ranging from room temperature (298 K) to 433K. The bulk resistance values estimated using complex impedance plots indicated that electrical conductivity of the synthesized solid specimens would vary from 2.9 x10-2 to 3.4 x10-6Scm-1 thus suggesting the present system to be ionic in nature. The extent of ionic conduction due to Ag + cation has also been analyzed using Wagner’s dc polarization technique whereas detailed structural characteristics of the various compositions derived from Fourier transform infrared (FTIR) spectroscopy and features of surface morphology of these samples obtained using scanning electron microscopy (SEM) have further supported the ionic nature of the chosen system and suggested possible application as a solid electrolyte in electrochemical devices.
Abstract: Nonlinear optical phase conjugation by degenerate four-wave mixing (DFWM) is an important technique with applications in many fields of science and technology. Phase conjugation by Degenerate four-wave mixing is observed in Disperse Orange-25 dye doped in Polymethyl methacrylate – metacrylic acid (PMMA-MA) polymer film under low-power, continuous-wave laser irradiation. A maximum phase conjugate efficiency of 0.22% has been obtained for probe beam intensity at 0.11 W/cm2. Phase conjugation is observed for both parallel- and orthogonally-polarized probe and pump beams. The maximum PC reflectivity is achieved when the angle between probe and forward pump beam is 7 degrees. The effects of dye concentration, intensity of backward, forward pump and inter beam angle between probe and forward pump beam on phase conjugation reflectivity are also studied. PC signal strength first increases and then decreases. PC reflectivity is increased by increasing the intensity of the backward and forward pump beam. The polarization and intensity profile are verified to be preserved in the conjugate signal. The predominant phase conjugation signal is attributed to the facts that reverse saturable absorption and large third order susceptibility of the dye molecules.
Abstract: The effect on the electrical characteristics of poly (methyl methacrylate) (PMMA) and poly (methyl methacrylate – co – butyl acrylate) (PMMABA) containing liquid crystal (E8) as dispersed material, is investigated in terms of electro optical and dielectric relaxation spectroscopy (DRS) technique. This polymer dispersed liquid crystal (PDLC) composite film is sandwiched between two glass slides with a transparent conductive substrate such as indium tin oxide (ITO). The resulting assembly forms an electro-sensitive material that can be switched from a OFF state to a ON state by the application of an external electric field or thermal ramp. In the present investigation PMMA / E8, PMMABA / E8 and PMMA+PMMABA / E8 composite films of 30/70 wt / wt % were prepared by Solution Induced Phase Separation (SIPS) method. Morphological study showed that homogeneous LC phase is embedded in a spongy – like polymer matrix. Electro optical behavior was determined under the condition of an externally applied AC electric field (0-200Vp-p, 50-1000Hz). DRS has been carried out in the frequency range from 20 Hz to 20 MHz and over the temperature range from 24°C to 75°C.The interfacial charge layer effect and qualitative evaluation of distribution of relaxation time is characterized by Cole-Cole model.
Abstract: Composite polymer electrolytes (CPE) have recently received a great attention due to their potential application in solid state batteries. A novel polyindole based Fe2O3 dispersed CPE containing lithium perchlorate has been prepared by sol-gel method. The crystallinity, morphology and ionic conductivity of composite polymer electrolyte were examined by XRD, scanning electron microscopy, and impedance spectroscopy, respectively. The XRD data reveals that the intensity of the Fe2O3 has decreased when the concentration of the polymer is increased in the composite. This composite polymer electrolyte showed a linear relationship between the ionic conductivity and the reciprocal of the temperature, indicative of the system decoupled from the segmental motion of the polymer. Thus Polyindole-Iron oxide composite polymer electrolyte is a potential candidate for lithium ion electrolyte batteries. The complex impedance data for this has been analyzed in different formalisms such as permittivity (ε) and electric modulus (M). The value of ε' for CPE decreases with frequency, which is a normal dielectric behavior in polymer nanocomposite.
Abstract: Polypyrrole (PPy) based metal composites have obtained considerable attention due to its fascinating properties such as appreciable electronic conductivity. This study is based on the system, pure polypyrrole (PPy) and nano copper doped polypyrrole (n-CuPPy) which were prepared by chemical oxidative polymerization method. The properties of PPy and n-CuPPy have been investigated by FT-IR,SEM-EDX and conductivity measurements. The FT-IR spectra showed the presence of all characteristics absorption peaks of PPy that is 881cm-1(=C-H out of plane vibration),1043cm-1(=C-H in plane vibration), 1182cm-1 (N-C strech vibration ) and 1552cm-1 (pyrrole ring vibration). The morphological structures and semi quantification of elements present in the pure and nano copper doped composite have been analysed using Scanning Electron Microscope with Energy Dispersive X-ray Spectroscopy. The conductivity measurements have been measured using two probe technique. We compare the conductivities of pure PPy with nanocomposite. The conductivity of n-CuPPy is 2x10-3 S/cm and PPy is 2.5x10-5 S/cm. The conductivity of n-CuPPy have been increased by two order when compared with PPy. The increase in conductivity in composite materials than PPy is due to the incorporation of nano copper particles into the PPy matrix.