Ultrasonics

Probing biomolecules by ultrasonic techniques is novel and powerful tool for characterizing their physico-chemical properties. Peptides find wide applications in drug production and as an ingredient in nutritional supplements. Glycyl-L-Glycine is the simplest dipeptide used in biochemical research and in the preparation of biodegradable polymers. Measurement of ultrasonic velocity plays an important role in the study of transport propeties of liquids/solution. In the present work, the acoustic and transport properties such as adiabatic compressibility, specific acoustic impedance, intermolecular free length, internal presure and free volume are computed for various molalities and at various temperatures. The results are analysed on the basis of solute-solvent interactions.

The state of any system can be defined completely by four observable properties, namely composition, pressure, volume and temperature. Study of thermodynamical properties of liquids and liquid mixtures play an important role in elucidation of the nature of molecular interactions. Internal pressure (?i) and free volume (Vf.) are the thermo dynamical parameters, which are useful in understanding the intra and inter molecular interactions in polymer solutions[1,2]. The internal pressure is known to be an inverse function of free volume. In the present work, the ultrasonic velocity, density and viscosity measurements have been made for the temperatures 303K, 313 K, 318 K and 323 K and at different concentrations of polyvinylidene fluoride in polar aprotic solvent i.e Dimethylacetamide. The variation of internal pressure and free volume with temperature and concentration has been carried out. The nature of polymer-solvent interaction and the effect of temperature and concentration on the molecular interaction are studied. The internal pressure is found to vary inversely with free volume and the values reveals that the relation ?i Vf x = constant, holds good for the above system.

The ultrasonic velocity and density are measured in binary mixture of ethyl ethanoate and sesame oil at 298.15K, 303.15K, 308.15K and 313.15K. Acoustical parameters such as isentropic compressibility, intermolecular free length, specific acoustic impedance, molar volume, available volume, volume at absolute zero, Van der waal’s constant, Rao’s Constant and Wada’s Constant have been evaluated.  Except isentropic compressibility all the other calculated parameters shows decreasing trend with the increase in concentration of solvent and increase in temperature. The variation of these parameters with temperature and concentration are used to study the intermolecular interaction existing between the components of the mixture.

Viscometric methods play a dominant role in studying the Polymer-Solvent interaction. Due to this interaction, there is an increase in viscosity of polymer solution over that of pure solvent. The intrinsic viscosity is the limiting value of the reduced viscosity at infinite dilution. The intrinsic viscosity has been used to study the extent of interaction between polymer and the solvent. In the present work, the intrinsic viscosity obtained through   adiabatic compressibility and viscosity data is applied to the solution of Poly Vinyl Pyrrolidone in polar solvent at 308 K, 313 K & 318 K.  Viscosity of the solvated part (?_s) is computed and its variation with molar concentration (n₂) is studied. The molar solvated volume (?_s) obtained from ?_s is compared with the values of ?_s computed using the traditional equation. The Huggin’s coefficients A_?   and B_? are determined from Viscosity study and compared with those obtained from solvation study.

The study of liquid properties using spectroscopy and acoustic methods In the present investigation, non-aqueous solutions of constitutes mining field for scientists. L. Arginine are studied. FTIR spectra have been taken for the sample solutions. The observed vibrational spectra are analysed. Ultrasonic velocity and density are measured for different temperatures(278.15K to 328.15K) and at various molalities. Using the above measurements, adiabatic compressibility solvation number, apparent molal compressibility, apparent molal volume and equivalent conductivity are computed. From the computed results structural influence of the salt in the solvent is studied. The results obtained from spectroscopic study are corroborated with the acoustic behavior of the solutions.

The density (?), viscosity (?) and ultrasonic velocity (U) have been measured for the binary mixtures of Brompheniramine with 1-Butanol at 303,308 and 313K. From the experimental data, several acoustic parameters such as adiabatic compressibility (?), free length (L_f), free volume (V_f), viscous relaxation time (?) and Gibbs free energy (?G) have been calculated. The excess values of the above parameters (?^E, L_f^E, V_f ^E ,?^E and ?G^E ) were also determined and interpreted in terms of molecular association such as hydrogen bonding formed between the liquid mixtures. The results show that hetero association and homo association of molecules decrease with increase in the temperature.

This paper presents the results of a RF receiver front-end design used in Personal Wireless Area Network (PWAN) and implemented in a 0.13µm CMOS process with source degenerated amplifier. Device models were used in MULTISIM and MATLAB Particle Swamp Optimization implementation to iteratively find a solution to optimal component values for user LNAtopology. To demonstrate the design methodology, a sub-mW fully integrated narrow-band sourcedegenerated cascode RF LNA is designed and simulated in a standard 0.13µm CMOSprocess to operate in the 2.4GHz band. The LNA achieves a voltage gain of 24 dB,noise figure (NF) of 1.4 dB, from a 4.4 mA supply current.

Ultrasonic velocity at 318 K in the binary systems of Methyl methacrylate + Toluene and Methyl methacrylate + Dimethylacetamide has been evaluated as a function of concentration and temperature, by using certain theoretical models like Nomoto’s relation, Impedance dependence relation, Van-Deal and Van-geel ideal mix relations, Free length theory and Jungie’s method. The experimental values of ultrasonic velocity are compared with theoretical values. The best suitable theoretical relation was found by calculating the percentage deviation and chi-square test.

Longitudinal, shear ultrasonic velocities and attenuation were measured in different compositions of the glass systems of 10TeO2.15BaO.(75-x)B2O3.xNiO and 10TeO2.15BaO.(75-x)B2O3.xWO3 (where x= 0 to 1 mol% in steps of 0.2) at room temperature by using pulser - receiver technique at 5 MHz. The glass samples were prepared by conventional melt-quenching method. The amorphous nature of the samples were ascertained using X-ray diffractometry (XRD). The density of the glass samples were measured by relative measurement method. The measured experimental values are utilized to evaluate elastic moduli, Poisson’s ratio, acoustic impedance, internalfriction, microhardness, Debye temperature, and thermal expansion coefficient. Trends of the co-ordination number, cross-link density, mechanical and thermal stability for the systems are discussed in terms of the structural changes taking place due to variations in composition.