Sonic Resonator

The adiabatic expansion method is not the best method of determining the heat capacity ratio. Much better methods are based on measurements of the velocity of sound in gases. One such method, described in Part B of this experiment, consists of measuring the wavelength of sound of an accurately known frequency by measuring the distance between nodes in a sonic resonance set up in a Kundt s tube. Methods also exist for determining the heat capacities directly, although the measurements are not easy. 

ASTM C-747 Modulus of elasticity and fundamental frequencies of carbon and graphite materials by sonic resonance... 

ASTM C1198 specifies a sonic resonance test for E and hence ( , for advanced ceramics. 

ASTM C 1198-01. Standard test method for dynamic Young s modulus, shear modulus and Poisson s ratio for advanced ceramics by sonic resonance... 

The elastic moduli are measured at temperatures above 500-600 °C by the sonic resonant frequency for different vibrational modes using long cylindrical rods of circular cross-section (Schafrik, 1977). The... 

Sonication of 0.05 M Hg2(N03)2 solution for 10,20 and 30 min and the simultaneous measurements of conductivity, temperature change and turbidity (Table 9.2) indicated a rise in the turbidity due to the formation of an insoluble precipitate. This could probably be due to the formation of Hg2(OH)2, as a consequence of hydrolysis, along with Hg free radical and Hg° particles which could be responsible for increase in the turbidity after sonication. The turbidity increased further with time. Mobility of NO3 ions was more or less restricted due to resonance in this ion, which helped, in the smooth and uniform distribution of charge density over NO3 ion surface. Hence the contribution of NOJ ion towards the electrical conductance was perhaps much too less than the conduction of cationic species with which it was associated in the molecular (compound) form. Since in case of Hg2(N03)2, Hg2(OH)2 species were being formed which also destroyed the cationic nature of Hg22+, therefore a decrease in the electrical conductance of solution could be predicted. The simultaneous passivity of its anionic part did not increase the conductivity due to rise in temperature as anticipated and could be seen through the Table 9.2. These observations could now be summarized in reaction steps as under ... 

In order to identify organic free - radicals present at quantifiable concentrations during the sonication of PCBs, we employed Electron Spin Resonance (ESR) with a spin trap, N-t-butyl-a-phenyl-nitrone (PBN). PBN reacts with the reactive free - radicals to form more stable spin-adducts, which are then detected by ESR. The ESR spectrum of a PBN spin adduct exhibits hyperfine coupling of the unpaired election with the 14N and the (3-H nuclei which leads to a triplet of doublets. The combination of the spin-adduct peak position and peak interval uniquely identifies the structure of a free-radical. 

The effects of ultrasound upon the permeability of the cell walls of the gram-negative bacteria Pseudomonas aeruginosa toward hydrophobic compounds particularly antibiotics have been examined [8]. The penetration and distribution of 16-dosylstearic acid (16-DS) in the cell membranes of the bacteria was quantified by a spin-labeling electron spin resonance (ESR) method. The results indicated that the intracellular concentration of 16- D S was higher in insonated cells and increased linearly with the sonication power. 

The step 1 product (200 mg) was treated with phenol (100 mg) and heated to 80°C and then further treated with borontrifluoride diethyletherate (0.09 mmol). The mixture immediately turned red and increased in viscosity. The vial was then heated to 105°C for 1 hour and then treated with 10 ml of distilled water and stood overnight at ambient temperature. The mixture was dissolved in 3 ml of toluene and sonicated. The soluble fraction did not show any polymer resonances by 1H-NMR spectroscopy indicating that the polymer has become crosslinked. 

In 1916, Hartmann discovered (Ref 7) that intense noise is generated from shallow cylindrical cavities when these are impinged by sonic gas jets, owing to resonant oscillations. Later it was shown that a very slender Hartmann whistle, with a length to diameter ratio of 30, exhibits intense heating at the closed end. Since that time, further improvements have taken place, principally in the incorporation of tapered or stepped cavities (Ref 7) culminating in the flueric match (see Fig 1)... 

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