Influence Of Ultrasonic Waves Research Articles

Non-Contact Interaction of Ultrasonic Wave on Laser Beam

The article presents the results of Matlab simulations and experimental studies of non-contact influence of ultrasonic wave on laser beam. A role of the air-gap and the influence of the air-gap on laser-ultrasonic transmission in optical fiber were examined. Two optical fibers were used with air-gap between them. One fiber was attached to a laser diode and positioned to pass through a hole in a sandwich type transducer and in a velocity transformer. In the velocity transformer (at its end), after leaving small air-gap, to the end of the transformer, the other optical fiber is attached. The second fiber can interact with a given biological structure.

Sonochemical Synthesis of DNA Nanospheres

Sonochemical Synthesis of DNA Nanospheres

Effects of Ultrasounds on the Heat Transfer Enhancement From a Circular Cylinder to Distilled Water in Subcooled Boiling

The main aim of this work is to investigate experimentally the influence of ultrasonic waves, on the heat transfer enhancement, from a stainless steel circular cylinder to distilled water, in subcooled boiling conditions. This study has carried on for a few years at the Department of Energetics “L.Poggi.” The effect was observed since the 1960s: Different authors had investigated the cooling effect due to the ultrasonic waves at different heat transfer regimes, especially from a thin platinum wire to water. They had found out that the highest heat transfer coefficient enhancement was in subcooled boiling conditions. So this paper has the purpose to clarify the physical phenomenon and optimize a large range of variables involved in the mechanism. It reports the experimental results obtained with ultrasound at the frequency of 38 kHz, at two different subcooling degrees, ΔTsub=25°C and 35°C. The heat fluxes applied on the cylinder, the ultrasonic generator power Pgen, and also the placement of the heater inside the ultrasonic generator tank were varied. The ultrasonic waves seem to be very useful for a practical application in the last generation electronic components’ cooling: They need dissipating huge heat fluxes and avoiding high temperatures (≈150°C), after that they could damage themselves.

Effect of Ultrasound and Xylanase Treatment on the Physical-Mechanical Properties of Bleached Eucalyptus Kraft Pulp

The modification on the fiber structure of bleached eucalyptus kraft pulp is a very attractive alternative for improve- ments in the properties of paper production. The enzymatic treatment by xylanases and ultrassonic treatments modify the characteristics of the fibers, has been reported. Therefore, the purpose of this study was to evaluate the influence of ultrasonic waves as a facilitator of the action of enzymes (hemicellulase) by modifying the physicochemical nature of fiber eucalyptus Kraft pulp, in order to improve the physical and mechanical properties of the paper. But it was observed the that idea of ultrasound acts as facilitator for action of enzymes can’t be affirmed, since in most properties XA-1 and XA-2 were equal statistically. It may be noted that the junction of ultrasound and xylanase provided improves on tensile index, specific elastic modulus and tensile energy absorption and a decrease of tear index on the mechanical properties of handsheet and it increased the opacity when the ultrasound was applied before xylanase.

Effects of ultrasound on the performance improvement of wastewater microfiltration through a porous ceramic filter

Filtration under an ultrasonic field is a technique that is gaining importance in the wastewater treatment research field, not only due to its ability as a cleaning mechanism, but also as a filtration intensifier. The main objective of this research was the study of the influence of ultrasonic waves on the filtration of theoilfield wastewater (known as produced water) in order to increase the operation performance and filter medium regenerative effectiveness. A 0.016 m² hollow cylindrical porous ceramic filter was submitted to the filtration of produced water by two mechanisms: conventional filtration under vacuum and filtration under theinfluence of ultrasonic waves. Experiments were carried out using synthetic produced water by analyzing the variables oil and grease content (O&G) and total suspended solids (TSS) for each filtration run. Backwashing of the filter medium with distilled water was also performed to evaluate the regeneration efficiency. During conventional filtration, permeate flux decreased gradually, becoming stable around 0.06 cm³.cm-2.s-1. Furthermore, in the filtration assisted by ultrasound, the permeate flux was around 0.15 cm³.cm-2.s-1. Therefore, ultrasonic waves provided an increase of about 150% in the permeate flux. Moreover, the sonication improved filter medium regeneration effectiveness, even under conditions of high TSS and O&G contents. Taking into consideration the very positive results associated with the application of ultrasonicwaves, this filtration technique is likely to become an important industrial process.

Influence of Ultrasonic Waves on the Processing of Cotton with Cationic Softener

AbstractIn recent years, the textile industry has been forced to develop new technologies to reduce energy and water consumption. The use of ultrasound in textile wet processing is one solution to this problem. The aim of this work was to investigate the effects of ultrasonic energy on the processing of cotton with a cationic softener. For this purpose, cotton fabric was treated with a fatty acid amide derivative cationic softener in water using ultrasonic energy during treatment. The physical properties of the fabrics treated under different conditions are discussed. The results show that the treatment of fabrics with softeners in an ultrasound bath is more effective compared to conventional methods and that it enhances the physical properties of the cotton.

Effect of Ultrasonic Waves on the Saccharification Processes of Lignocellulose

AbstractThe pretreatment and saccharification process of lignocellulose were subjected to ultrasonic waves to enhance the saccharification rate. The morphology, structure and crystal performance of the original and treated lignocellulose samples were characterized by SEM and FTIR. Moreover, the effect of different pretreatment methods on the structure of the raw materials and the influence of ultrasonic waves on the saccharification rate, were studied. SEM photographs show that the surface conformation of the granulated raw material is not changed, because the energy of the ultrasonic vibration is too low to cause changes to its structure. A FTIR spectrum shows that the ultrasonically assisted alkali pretreatment effectively destroys the intermolecular hydrogen bonding of lignocellulose and decreases its crystallinity. The catalytic efficiency of cellulase was increased by 70 % under ultrasonic treatment. Therefore, the ultrasonically assisted alkali pretreatment can improves the degradation rate of lignin and the saccharification rate of zymohydrolysis. The mechanism of the effect of ultrasonic waves on the enzymatic catalysis process is also discussed in detail.

Investigation of the ultrasonic wave influence on magnetic ordering in a 20 × [Fe(20 Å)/Cr(12 Å)]/MgO layered structure

A 20 × [Fe(20 A)/Cr (12 A)]/MgO structure excited by an ultrasonic wave was investigated by polarized neutron reflectometry. It was found that magnetic domains oscillate and their effective size decreases in weak magnetic fields. In close-to-saturation fields, a magnetic lattice is formed in the layered structure; the interplanar spacings in this lattice change with an increase in the field strength and as a result of the excitation of the structure by an ultrasonic wave.

Influence of Ultrasonic Wave on the Current Efficiency of the FeO42- in Alkalinity Solution

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Use of a droplet nucleation analyzer in the study of water freezing kinetics under the influence of ultrasound waves

In this report we present a new instrument (a droplet nucleation analyzer) to be used in the study of the influence of ultrasonic waves on the freezing of pure water. This influence can be of great interest in the cryopreservation of biological material. Two different types of experiments have been carried out. In the first set of experiments, ultrasound waves were used during the cooling process. In the second set, ultrasound was applied prior to the cooling process, trying to quantitatively reproduce some experiments in which the ice nucleation temperature of water was successfully decreased. A theoretical discussion of the results is also presented.

Experimental evidence of ultrasonic stimulation of brine-oil flow through a porous rock in laboratory conditions

Laboratory experiments have been carried out to study the influence of high-frequency (20 kHz) acoustic waves on the flow of brine through a core sample of reservoir rock containing residual oil. The experiments were done at reservoir conditions with respect to temperature and pressure. Below a certain critical level of the acoustic intensity the relative permeability for the flow of brine is independent of the acoustic intensity and there is no flow of oil out of the core. However, above the critical level the relative permeability for the brine flow jumps to a significantly higher value and oil starts to flow from the core. These experimental results are in agreement with a theoretical model proposed by Graham and Higdon [Oscillatory flow of droplets in capillary tubes Part 2 Constricted tubes. J. Fluid Mech. 425, 55–77 (2000)]. The model is based on a microscopic picture of oil drops (surrounded by flowing brine) being trapped inside the pores of the reservoir rock. Under the influence of ultrasonic waves the oil drops oscillate and can escape from their pores above a critical level of the acoustic intensity.

Influence of the Precipitation Medium and Ultrasonic Wave on the Synthesis of Iron Oxide

Synthesis of Iron oxides by air oxidation of <TEX>$FeSO_4$</TEX> solutions in the presence of NaOH, Diethylenetriamine (DETA), Butylamine (BA) and influence of ultrasonic wave were investigated by XRD, SEM and particle size analyzer. As the DETA addition increased to 0.05 mol, <TEX>$Fe_3O_4$</TEX> was formed with goethite(<TEX>$\alpha$</TEX>- FeOOH) and <TEX>$Fe_3O_4$</TEX> single phase was formed above 0.18mol of DETA. As the BA addition increased, the XRD peak intensity of (020) face of lepidocrocite(<TEX>$\gamma$</TEX>-FeOOH) was developed until the formation of <TEX>$Fe_3O_4$</TEX> and reduced the size of the iron oxide particles formed. Ultrasonic wave reduced the size of the iron oxide particles but gave little effects on the iron oxide particles synthesized by amine.

Influence of ultrasonic waves in the reduction of nitrate to nitrite by hydrazine–Cu(II)

Colorimetric methods are still important for determining nitrate and nitrite. A critical step in the use of these methods to determine nitrate in low concentrations is the reaction time required to totally reduce nitrate to nitrite, i.e., 24 h in the dark. This work involved a study of the influence of ultrasonic irradiation on the nitrate reduction reaction by hydrazine. Our findings indicated that ultrasonic irradiation, associated with copper(II) ion as a catalyst, increased the redox reaction rate, decreasing the reaction time to about 10 min when the power of the ultrasonic irradiation was set in 14.0357 W. The strong influence of the ultrasonic irradiation in the reduction reaction rates can be sustained by an excellent linear correlation ( R 2 = 0.9993) between the kinetic constants and ultrasonic powers. Nitrate conversion also increased from 68% to 98% at the latter conditions. It thus become clear that high intensity ultrasound is very beneficial for this reduction reaction to proceed in good yield and in short reaction time in comparison to its silent reaction.

Investigations on Capillary and Viscous Displacement Under Ultrasonic Waves

Abstract In this paper, the influence of ultrasonic waves on capillary and viscous displacement of oil in porous media was investigated. Capillary (spontaneous) imbibition experiments were conducted using various fluid pairs such as air-water, mineral oil-brine, mineral oil-surfactant solution, kerosene-surfactant solution, and mineral oil-polymer solution. Berea sandstone and Indiana limestone cores were used as the matrix. Oil saturated cores were immersed into the aqueous phase and subjected to high intensity ultrasound from a specially designed ultrasonic chamber. The resulting recovery was recorded against time, and compared to a control experiment without ultrasound. A substantial increase in ultimate recovery was observed for most of the fluid pairs, with some improvements in recovery rate. To further investigate whether ultrasound induces a perturbation at the liquid-liquid interface of immiscible fluids, a series of Hele-Shaw type experiments were run. The resulting fingering pattern was strongly dependent on the interfacial tension of the fluid pair, and the injection rate. Ultrasound stabilized the fluid-fluid front of high interfacial tension fluid pairs, but generated larger instabilities when interfacial tension was low. Introduction For the past four decades, researchers have explored the use of acoustic energy to improve oil recovery that could potentially be an economic and environmentally-friendly alternative to current IOR methods. Beresnev and Johnson(1) provide an extensive review of the major developments of acoustic stimulation and its limitations. Guo et al.(2) discuss recent field results of seismic stimulation in China. Despite numerous promising field trials and patents, the exact mechanism behind ultrasonic stimulations is poorly understood. Most of the findings have been speculative with little experimental verification. The reason is two-fold. Firstly, the problem is very complex, involving a superposition of several different mechanisms. Secondly, it is not certain how far an acoustic wave propagates into the reservoir, or how such propagation occurs. Ultrasonic applications are limited to the near-wellbore area due to the high attenuation through the rock or fluids. As a consequence, most research in recent years has shifted to low energy, low frequency waves that can propagate several kilometres into the reservoir. However, because low frequency waves disperse into high-frequency harmonics as they travel through a porous medium, one would still expect ultrasonic waves to be present in the reservoir. An analytical treatment of compression and shear wave propagation in saturated porous media was first developed in two classic papers by Biot.(3, 4) . Acoustic waves are usually applied in three ways: pressure pulsing, down-hole vibration, and surface vibration. Applications range from enhanced oil recovery (EOR) to well stimulation, in situ upgrading, wellbore cleaning, and soil remediation. Acoustic stimulation is believed to positively contribute to the flow of oil in porous media by:Increasing the relative permeability of the phases;Reducing the adherence of wetting films onto the rock matrix, due to non-linear acoustic effects such as in-pore turbulence, acoustic streaming, cavitation, and perturbation in local pressures(5);Reducing surface tension, density, and viscosity as a consequence of heating by ultrasonic radiation(6);Altering of rheological properties of non-Newtonian fluids;

Synthesis of branched antisense oligonucleotides having multiple specificities: Treatment of hormone insensitive prostate cancer

Antisense oligonucleotides (oligos) directed against transforming growth factor-alpha (TGF-alpha) and its binding site, the epidermal growth factor receptor (EGFR), have demonstrated in vitro and in vivo efficacy against both the PC-3 and LNCaP prostate tumor models. In an attempt to increase the efficiency of these oligos a new type of antisense compound called a bispecific oligo has been evaluated in vitro both alone and in combination with traditional chemotherapeutic agents. These bispecifics, which were first proposed in this journal in 2004, include binding sites for both TGF-alpha and EGFR along the same stretch of complementary DNA. Such bispecifics are able to deliver essentially two antisense activities in an equal molar ratio and can be directed against mRNA encoding proteins of different biochemical pathways. The first bispecifics were developed against two proteins regulating a single autocrine loop. Subsequent bispecifics have been developed which target both EGFR and the apoptosis regulating protein bcl-2. Bispecific activity of a single linear sequence oligo has already been shown to have efficacy. To further develop this multispecific approach, we now propose a branched antisense compound, again, having multiple binding site activities (to complementary sequenced mRNA). Active oligos would be attached to a fat soluble backbone which might enhance targeting and also intracellular entry, release and activity. Such a structure would also permit the customization of these branched forms to include oligos targeting specific proteins related to the growth of various tumor types. Problems associated with the development of antisense oligos have included both membrane solubility and specific targeting. By designing this branched form of antisense structure, multiple activities can be retained (added), solubility improved and delivery enhanced. Such a new formulation would include several antisense oligos covalently bound to and branching off from a lipid-like backbone. An elongated hydrocarbon chain would increase fat solubility and would permit oligo incorporation into nanoparticles or liposome derived delivery vehicles. Specific delivery of oligos could also be enhanced by the tendency of these nanoparticle or liposomal microbubbles to be disrupted under the influence of ultrasonic waves beamed at the targeted tissue.

Shallow Levels Characterization in Epitaxial GaAs by Acousto-Optic Reflectance

Optical spectra of light reflection are detected under an influence of ultrasonic wave (UW)on a GaAs wafer. The differential spectrum is calculated as a difference between those taken under UW and without that influence on a sample. This acousto-optic differential reflectance(AODR) spectrum contains some bands that represent the energetic levels of the shallow centers in a sample. A physical basis of this technique is related to a perturbation of local states by UW. Here, a method is developed for characterization of local states at the surfaces and interfaces in crystals and low-dimensional epitaxial structures based on microelectronics materials. A theoretical model is presented to explain AODR spectra. Also, experiments using epitaxial GaAs structures doped by Te were made. Finally, theoretical and experimental results show that acousto-optic reflectance is an effective tool for characterization of shallow trapping centers in epitaxial semiconductor structures.

Influence of ultrasonic waves on phosphate determination by the molybdenum blue method

Polymeric bonds between molybdate monomeric ions in acidic medium were broken by 40 kHz ultrasonic wave irradiation, improving the reaction kinetics with o-phosphate in the presence of ascorbic acid. It could be assumed that the ultrasonic wave irradiation of molybdate solution in acidic medium during 1.0 min was sufficient to increase the rate of the molybdenum blue formation. The approach was applied to the o-phosphate determination in natural waters. Precise results were obtained in the range from 0.05 to 0.50 μg ml −1 ( r=0.9994; N=6), and the detection limit was estimated as 0.027 μg ml −1 PPO 4. Advantages over the classical analogous procedure are emphasised.

Effects of ultrasonic irradiation on the spectrophotometric determination of nickel with dimethylglyoxime

Influence of ultrasonic waves in the spectrophotometric determination of nickel with dimethylglyoxime (DMG) was investigated and interferences from foreign species such as Co 2+, Fe 2+ and Cu 2+ were studied. A 1.5-fold sensitivity enhancement in relation to the conventional method involving nickel oxidation with persulfate was attained. In addition, operator handling and reagent consumption were lessened. The analytical curve was linear from 0.15 to 1.5 mg l −1 Ni and detection limit was estimated as 13 μg l −1 Ni. The procedure was applied to the analysis of alloys, containing Co, Fe and Cu in different proportion, and accuracy was assessed by using certified reference materials.

Viability of plant cells in ultrasonic fields

The influence of ultrasonic waves on suspension plant cell cultures (e.g., petunia and carrot) has been investigated. The dependency of viability, cell density, miototic division, and regeneration, on the controlled acoustic parameters’ frequency of sound, energy density, treatment time, and wave type, is presented. Special focus is on the investigation of the influence of propagating plane waves, because these allow a spatially almost invariable acoustic pressure amplitude and, as a consequence, the same acoustic parameter values for all cells in the treated suspension volume. [Work supported in part by the European Commission, Contract No. ERBFMRXCT970156.]

Understanding and improving the deposition conditions of SiO2 thin films obtained by ultrasonic sol-gel procedure

Sol-gel deposition of an ultrasonically atomized aerosol has been proven to be a convenient thin film deposition method. Flexibility of the ultrasonic process allows the use of a large range of source solutions. In this paper we describe and discuss the deposition conditions of SiO2 films. The chemical parameters are contemplated and we discuss the influence of ultrasonic waves on the reliability of our process. Source solutions and SiO2 film properties are studied by viscosimetry, Fourier Transform IR spectroscopy and spectroscopic ellipsometry.