Influence Of Ultrasonic Irradiation Research Articles

The bacterial inhibitory ability and in vivo drug release pattern of a new drug delivery system: ciprofloxacine/tricalcium phosphate delivery capsule.

The bacterial inhibitory ability of a new drug delivery system (DDS): Ciprofloxacine/tricalcium phosphate delivery capsule (CTDC), its in vivo drug release pattern, and the influence of ultrasonic irradiation on its drug release were investigated. It was found that CTDC had a strong and sustained inhibitory ability to some common pathogens of bone and joint infections, such as staphylococcus aureus, escherichia coli and pseudomonas aeruginosa. In vivo drug-release study in animals demonstrated a high concentration of ciprofloxacine in the bone tissue surrounding CTDC which was placed in the greater trochanter of the rabbit and continued to release ciprofloxacine for at least 5 weeks and the blood level of ciprofloxacine was low. In vivo study also showed ultrasonic irradiation could increase the amount of ciprofloxacine released from CTDC, which may be an economical, effecient and safe new method to achieve the control of drug release from DDS.

Ultrasonic Modification of Light Emission from Electrochemiluminescence Processes

The influence of ultrasonic irradiation on the electrochemiluminescence evolved from the electrochemical oxidation reaction of tris(2,2‘-bipyridyl)ruthenium(II) chloride [Ru(bpy)3Cl2] or tris(1,10-phenanthroline)ruthenium (II)chloride [Ru(phen)3Cl2] in aqueous oxalate has been examined. Under the conditions described here, insonation resulted in an increase in the luminescence yield of over 100%, in a highly reproducible manner. These effects were found to result from ultrasonic irradiation and can be understood with reference to the changes in mass transport of reactants through the bulk solution and modification of the electrode Nernst diffusion layer that have been observed by other workers. A relationship between the light intensity and the square of the cell current was observed under various ultrasound powers, and it was found that this is consistent with the kinetic scheme proposed by Bard et al. for the electrooxidation reaction under silent conditions. This indicates that the reaction mechanism under insonation is consistent with that proposed for the silent reaction. The electrochemiluminescence spectrum under insonation was measured with greater precision than previously and was shown to be identical to that under silent conditions. Luminescence quenching by oxygen, problematic in earlier reports, was measured under insonation and also with greater precision than previously in the silent system. The Stern−Volmer relationship was obeyed under both sets of conditions, and oxygen quenching phenomena appear to be unaffected by insonation of the system.

Effect of ultrasound on the formation of ZrO 2 sols and wet gels

The influence of ultrasonic irradiation (sonocatalysis) on the formation of ZrO 2 sols and gels was studied by small-angle X-ray scattering (SAXS) using the LURE synchrotron facility. The starting solutions consisted of mixtures of Zr-tetrapropoxide and acetic acid. It was found that sonocatalysis increases the rate of formation of linear polymeric clusters in the starting solution but does not influence the growth process. The gelation time depends on both the irradiation time and ultrasonic power. The gyration radius, R G, of particles obtained under ultrasound is smaller than that of classical gels without ultrasonic irradiation.

A comparative analysis of machining characteristics in ultrasonic assisted EDM by the response surface methodology

This paper comprehensively evaluates the influence of ultrasonic irradiation of spark gap on EDM characteristics for both planing and drilling operations. A set of comparative experiments were carried out and the analysis of the results was based on standard statistical techniques. The response surfaces and the corresponding response functions were determined for major performance indices, such as machining rate, tool wear rate, corresponding wear ratio and surface roughness. With the application of ultrasonics the machining rate and surface finish improved significantly and, although the tool wear rate also increased, the wear ratio was not influenced significantly. The improvement in machining rate was highly significant in the drilling operation.

Effects of mechanical stress on the reactivity of polymers: activation of acid hydrolysis of dextran by ultrasound

The influence of ultrasonic irradiation on the kinetics and mechanism of acid hydrolysis of dextran is studied. The increase in the rate constants of the combined hydrolytic and ultrasonic degradation was investigated as a function of the molecular weight of dextran. For molecular weights higher than the limiting value for ultrasonic degradation the rate constants are proportional to the molecular weight raised to the power of 4/3; for molecular weights below the limiting value the rate constants are proportional to the molecular weight raised to the power of 5/6. The effects are discussed in connection with stretching forces which act on the polymer molecules as a result of ultrasonic cavitation.

LOW TEMPERATURE CRYSTALLIZATION OF SOLID POLYETHYLENE TEREPHTHALATE UNDER THE ULTRASONIC IRRADIATION

The low temperature crystallization of polyethylene terephthalate (PET) under the ultrasonic irradiation was studied by the density gradient tube method, DSC and X-ray technique, and the crystallization behavior was compared with that of PET on annealing. The results obtained are as follows:1. The influence of ultrasonic irradiation on crystallization rate depended on the temperature. Ultrasonic irradiation accelerated the crystallization of PET at temperatures of about 80°C to 125°C. This crystallization behavior of PET can be described in terms of the rate of segmental motion. Long segment moves easily in the ultrasonic field, as the potential barrier to rotation of bonds is lowerd. Additional X-ray and DSC data also support the above result.2. The value of the Avrami exponent n, for the crystallization of PET under the ultrasonic irradiation at 100°C-102.5°C was 2.9-3.1 and n for the crystallization of PET on annealing at 105°C-110°C was 1.8-2.3.3. In the similar manner, ultrasonic irradiation accelerated the solid-state crystallization of oriented amorphous PET.

Spectrophotometric Studies on the Ultrasonically Irradiated Human Plasma Lipoproteins

Human plasma lipoproteins (high density lipoprotein, low density lipoprotein) are prepared by ultracentrifugal method. Followed delipidation of these lipoproteins is performed with ether containing SDS to obtain their apoproteins. These lipoproteins and apoproteins are subjected to ultrasonic irradiation (20 kc) to accelerate the deterioration. The UV-spectra of ultrasonically irradiated preparations generally increase, and the maximum absorption shifts to the shorter wavelength by ultrasonic irradiation. Similar changes of UV-spectra are observed between ultrasonically irradiated lipoproteins and the lipoproteins stored for long term. In this paper the authors discussed about the influences of ultrasonic irradiation on lipoproteins.

The degradation of polymer molecules in solution under the influence of ultrasonic waves. Part I. Kinetic analysis

AbstractStarting from the assumption that a polymer molecule in solution will only degrade under the influence of ultrasonic irradiation if both the resulting fragments are greater than Pe/2 in size, where Pe is the so‐called limiting degree of polymerization, rela tionships are derived giving the rate of degradation in terms of rate of breaking of bonds. If dBi/dt the rate of breakage of bonds in molecules of size Pi, the proposed rate equations are: dBi/dt = k(Pi – Pe)ni for Pi > Pe and dBi/dt = 0 for Pi ⪕ Pe, where k is a constant characteristic of the system and ni is the number of molecules of size Pi. Solutions of this equation are given for three sets of conditions.

The degradation of polymer molecules in solution under the influence of ultrasonic waves. Part II. The rate equation and the limiting degree of polymerization

AbstractThe breaking of polymer bonds in solutions of polystyrene, polyvinyl acetate, and polymethyl methacrylate in benzene and toluene while under the influence of ultrasonic irradiation has been studied by following the consumption of a radical scavenger, α,α′‐diphenyl‐β‐picryl hydrazyl added to the solution. The results are consistent with the rate equation proposed in an earlier paper, dBi/dt = k(Pi – Pe)ni and its relevant solutions, where dBi/dt, Pi and ni are, respectively, the rate of breakage of bonds, the degree of polymerization, and the number of molecules of the ith species, and where Pe is the limiting degree of polymerization, k is a constant, characteristic of the system and dependent on the weight concentration of the solution. Earlier literature is discussed and, in one case, the results are found to be more consistent with the above equation than with the forms: dB/dt = k(P ‐ Pe) and dB/dt = k log P/Pe. Values of Pe found by extrapolation are 1700, 2000 and 2800, respectively, for polystyrene, polyvinyl acetate, and polymethyl methacrylate. The various values of Pe for these systems to be found in the literature are discussed.

Influence of ultrasonic irradiation on temperature and blood flow in human skeletal muscle.

The circulatory response to ultrasonic irradiation of the upper limbs was measured under controlled conditions by venous occlusion plethysmography. Volumetric blood flow changes were related to temperature measurements in the treated tissues. Ultrasonic irradiation of the extremities was not found, per se, to be an effective means of promoting a sustained increase in blood flow. The information obtained on the nature of the circulatory effects of ultrasonation permits a more satisfactory evaluation of this new method of treatment.