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Microalgae, a sustainable source of multi beneficial components has been discovered and could be utilised in pharmaceutical, bioenergy and food applications. This study aims to investigate the sugaring-out effect on the recovery of protein from wet green microalga, Chlorella sorokiniana CY1 which was assisted with sonication. A comparison of monosaccharides and disaccharides as one of the phase-forming constituents shows that the monosaccharides, glucose was the most suitable sugar in forming the phases with acetonitrile to enhance the production of protein (52% of protein). The protein productivity of microalgae was found to be significantly influenced by the volume ratio of both phases, as the yield of protein increased to 77%. The interval time between the sonication as well as the sonication modes were influencing the protein productivity as well. The optimum protein productivity was obtained with 10 s of resting time in between sonication. Pulse mode of sonication was suitable to break down the cell wall of microalgae compared to continuous mode as a lower protein yield was obtained with the application of continuous mode. The optimum condition for protein extraction were found as followed: 200 g/L glucose as bottom phase with volume ratio of 1:1.25, 10 s of resting time for ultrasonication, 5 s of ultrasonication in pulse mode and 0.25 g of biomass weight. The high yield of protein about 81% could be obtained from microalgae which demonstrates the potential of this source and expected to play an important role in the future.

Silver Oxide (Ag2O)-Guar gum nanocomposite was fabricated via a simple sonochemical co-precipitation method. The obtained photocatalyst was characterized with various techniques such as X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, UV–vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, scanning electron microscopy and transmission electron microscopy along with energy dispersion X-ray spectroscopy. The findings have demonstrated that Ag2O nanoparticles are spherical of 5−20 nm and were dispersed on the surface of polysaccharide guar gum to form Ag2O-guar gum nanocomposite. The as-synthesized nanocomposite was enacted as a competent photocatalyst for the reduction of nitrobenzene and oxidation of benzyl alchohol. The conversion efficiency for the reduction of nitrobenzene was 96 % with the addition of sodium borohydride, and the conversion of benzyl alcohol was 98 %. The highly efficient photocatalytic activity was due to the exceedingly dispersed Ag2O-guar gum nanocomposite where effective separation rate of energy driven electron-hole pairs and stronger light absorption occurs. The possible mechanism of the reactions was implicated in understanding the active species involved in the photocatalytic study.

Dicofol, an extensively used organochlorine pesticide and a recommended Stockholm convention persistent organic pollutant (POP) candidate is well known for its endocrine disruptive properties. The sonochemical degradation of Dicofol in aqueous media has been investigated using a 20-kHz probe type sonicator with power inputs from 150 to 450 W. The degradation rate was determined as a function of concentration of Dicofol, solution pH, bulk phase temperature, ultrasonic power density and H2O2 addition. At optimum operating conditions, the pseudo-first-order degradation rate constant (k) was determined to be 0.032 min−1 and the extent of degradation was found to be 86% within 60 min of ultrasound treatment. High performance liquid chromatography (HPLC) and Gas chromatography coupled with mass spectroscopy (GC-MS) analysis indicated the presence of degraded products. The obtained results of Dicofol degradation and control experiments in the presence of H2O2 and radical scavenger test suggest thermal decomposition along with radical attack at bubble-vapor interface to be the dominant degradation pathway. Sonochemical treatment is effective and promising for successful removal of harmful pesticides such as Dicofol and superior removal efficiency for other POPs is expected in the near future with the successful implementation of ultrasound-based wastewater treatment.

Glassy carbon particles (millimetric or micrometric sizes) dispersions in water were treated by ultrasound at 20kHz, either in a cylindrical reactor, or in a "Rosette" type reactor, for various time lengths ranging from 3h to 10h. Further separations sedimentation allowed obtaining few nanoparticles of glassy carbon in the supernatant (diameter

The present study investigated the anti-inflammatory and analgesic activities of novel aspirin oil-in-water (O/W) nanoemulsion and water-in-oil-in-water (W/O/W) nano multiple emulsion formulations generated using ultrasound cavitation techniques. The anti-inflammatory activities of nanoemulsion and nano multiple emulsion were determined using the λ-carrageenan-induced paw edema model. The analgesic activities of both nanoformulations were determined using acetic acid-induced writhing response and hot plate assay. For comparison, the effect of pretreatment with blank nanoemulsion and reference aspirin suspension were also studied for their anti-inflammatory and antinociceptive activities. The results showed that oral administration of nanoemulsion and nano multiple emulsion containing aspirin (60 mg/kg) significantly reduced paw edema induced by λ-carrageenan injection. Both nanoformulations decreased the number of abdominal constriction in acetic acid-induced writhing model. Pretreatment with nanoformulations led to a significant increase in reaction time in hot plate assay. Nanoemulsion demonstrated an enhanced anti-inflammatory and analgesic effects compared to reference suspension while nano multiple emulsion exhibited a mild inhibitory effects in the three experimental animal model tests. The results obtained for nano multiple emulsion were relatively lower than reference. However, administration of blank nanoemulsion did not alter the nociceptive response significantly though it showed slight anti-inflammatory effect. These experimental studies suggest that nanoemulsion and nano multiple emulsion produced a pronounced anti-inflammatory and analgesic effects in rats and may be candidates as new nanocarriers for pharmacological NSAIDs in the treatment of inflammatory disorders and alleviating pains.

2-(Trimethylsilyl)ethanol as a new alcohol equivalent has been employed for copper-catalyzed coupling of aryl iodides. Using mild reaction conditions, it has been observed that substituted phenols and phenols with sensitive functional groups can be readily prepared.

Carbamic acid 2-trimethylsilylethyl ester (Teoc-NH 2 ) serves as an ammonia equivalent in the palladium-catalyzed amination of aryl bromides and aryl chlorides. Anilines with sensitive functional groups can be readily prepared using these amine derivatives.

A new approach has been developed for the preparation of Y(OH)3:Eu and Y2O3:Eu nanosheets using the sol–gel method and hydrothermal reactions. XRD patterns showed that the product was purely hexagonal-phase Y(OH)3. TEM images revealed that the nanosheets are square shaped (1 × 1 μm2) with a thickness of several tens of nanometers. In addition, it was found that cubic-phase Y2O3 nanosheets can be obtained by calcination of Y(OH)3 at 900 °C for 1 h. More importantly, the thus-prepared Y(OH)3:Eu and Y2O3:Eu nanosheet phosphors were found to exhibit a relatively high photoluminescence (PL) intensity.

The paraffin particles were prepared by quenching process after sonicating the solution of paraffin and water at 80 degrees C. The resultant paraffin particles were then used as template for the preparation of macroporous zirconia materials. For this, zirconium normal butoxide (ZNB) modified with triethanolamine (TEA) was first hydrolyzed by water containing the dispersed paraffin particles with the surfactant, Sodium di(2-ethylhexyl) sulfosuccinate. This resulted in the formation of a slurry consisting of hydrolyzed sol and paraffin particles. After centrifugation, a cake packed with hydrated sol and paraffin particles were obtained which was then subjected to heat treatment. The sample obtained after heat treatment contained finely dispersed pores in the size range from 40 nm to 2 microm. Moreover, using the present approach it has also been observed that, change in pore size of zirconia wall is possible with a change in size of the paraffin particles. Thus, the present approach is a novel way of producing porous materials as the particle size of the template could be changed and templates become hard when they were molded as compared to the conventional methods in which there is no change in phase for the templates under 100 degrees C.

A CuO–ZrO2 catalyst of nanometer size was prepared using a simple precipitation technique, assisted by cavitation, and induced by an environmentally friendly ultrasonic technique. BET surface areas of 349.2 m2 g−1 for the as-prepared catalyst and 72.4 m2 g−1 for the catalyst calcined in air at 500 °C were obtained when the precursors were subjected to 70% ultrasonic intensity for 4 h. On the other hand, by following a conventional precipitation method using similar precursors, a surface area of 72 m2 g−1 was obtained when the precursors were heated to only 80 °C for 20 h. More importantly, only the application of ultrasound lead to the formation of a mesoporous structure. To confirm the ultrasonic cavitational effect in this process, the affect of the ultrasonic intensity in increasing the surface area, as well as in generating the mesopores, was also investigated. Furthermore, from studies of the catalytic activity for decomposing N2O, it has been observed that the catalyst obtained with 70% ultrasonic intensity clearly exhibits an increased activity compared to the catalyst prepared using 20% ultrasonic intensity. These results clearly indicate that ultrasound-induced cavitation is a new and rapid method for the preparation of supported catalysts. The products were characterized by nitrogen adsorption–desorption isotherms, TGA, XRD, TEM, EDAX, XPS and XRF measurements.

In the past decades, a great deal of attention has been focused on mechanical, thermal or chemical pretreatments of lignocellulosic and algal biomass for the production of biofuel. This chapter is focused on the potential of ultrasound (US) technology in pretreating the biomass to enhance the conversion of cellulose to fermentable sugars and also the disintegration and component extraction of microalgae for the generation of bioethanol or biogas. In addition, US can supplement existing biomass pretreatment methods to greatly enhance their performance and their efficacy. Low frequency ultrasound (LFU, 20–100 kHz) is commonly used in biomass processing, particularly in processes that require intense physical effects such as cell disruption and polymer degradation. High frequency ultrasound (HFU, 400 kHz–2 MHz) recently attracted considerable interest as potential alternative technique for pretreating both the lignocellulosic and algal biomass for sustainable biofuel production. HFU is gaining increasing importance because of its environmentally sound and energy-saving production method since it demands lower energy input for the conversion of biomass. It not only saves time and energy but also lowers the chemical/enzyme dosage and hence novel and considered to be a new sustainable and environmentally-friendly green technique. Although many studies have shown the promise of ultrasound in the cell breakdown for enhanced enzymatic hydrolysis, there is limited information in the application of HFU on biomass pretreatment processes. This chapter provides an overview on the fundamentals of US, the critical parameters that control the conversion of biomass, challenges involved with the application of US in the biomass conversion and its future perspectives.

The effects of ultrasound originate primarily in acoustic cavitation. The cavitation bubbles collapse violently enough to lead to interesting chemical effects, known as sonochemistry. There is a great need to relate the efficiency of sonochemical reaction to the energy of ultrasonic irradiation used to produce them. In this paper, three OH radical dosimeters, Fricke dosimeter, terephthalate dosimeter, and iodide dosimeter, are compared from the analytical point of view. The dosimeters based on photometry, i.e., Fricke and iodide, produced reliable and reproducible results, but the sensitivity is not enough for special applications, such as chemical monitoring of single bubble cavitation. The dosimeter based on fluorometry, terephthalate dosimeter, offered high sensitivity, 1.2×10 11 molecules ml −1 . The effects of some experimental parameters in sonochemistry, i.e., solution temperature and the dissolved gas species, were evaluated with the dosimeters.

We report on a simple and novel sonochemical method for the preparation of polyaniline (PANI), as well as its composite, with Au nanoparticles. This technique utilizes ultrasound radiation as an energy source to facilitate the reaction by reducing the reaction time, as well as significantly increasing the yield. The tremendous increase in the reaction rates is explained on the basis of the intensive bubble collapse conditions, which rapidly generate the oxidative radicals necessary for polymerization.

Macroporous alumina materials were synthesized by using yeast cells as bio-templates. Aluminium isopropoxide (AIP) modified with triethanolamine (TEA) was first hydrolyzed by water containing the dispersed yeast cells. This resulted in the formation of slurry consisting of hydrolyzed sol and yeast cells. After centrifuging, the cake which is packed with hydrated sol and yeast cells was subjected to heat treatment. The obtained sample after heat treatment contained finely dispersed pores ranging in size from 1.5 to 2.0 μm. Under the present experimental conditions, the thickness of alumina wall was also controlled by changing the ratio of yeast cells to AIP.

Zirconia hollow spheres were prepared using yeast cells as templates. Zirconium butoxide (ZNB) was used as a precursor and treated with triethanolamine (TEA) in order to obtain a basic aqueous zirconium hydroxide solution. Thus obtained basic zirconium hydroxide solution was then nucleated heterogeneously using yeast cells as templates. The results of this investigation show that the formed zirconia hollow spheres either keep the shape of the yeast cells or otherwise have a wrinkled shell. The shell of hollow spheres heated at 973K for 3 hours was from 0.1 to 0.25μm in thickness and consisted of the nano crystals.

Bimodal (meso/macro) porous alumina materials were synthesized using yeast cells as bio-templates. Aluminium isopropoxide (AIP) modified with triethanolamine (TEA) was first hydrolyzed by water containing the dispersed yeast cells. This resulted in the formation of slurry consisting of hydrolyzed sol and yeast cells. After centrifuging the solution, the obtained cake which is packed with hydrated sol and yeast cells was subjected to heat treatment. The sample after heat treatment contained finely dispersed bimodal (meso/ macro) pores ranging in size from 1.5 to 2.0 μm and several nm. Under the present experimental conditions, the thickness of alumina wall was also controlled by changing the ratio of yeast cells to AIP. It was also observed that with an increase in the thickness of the wall, the size of the pores decreased. [DOI: 10.1380/ejssnt.2005.405]

The present work analyses, in detail, the optimization of a sonochemical process with respect to concentration of precursor and power supplied in a system. This is due to that even a small change in power dramatically changes the high-energy conditions created with the bubble collapse. A model reaction that has been considered for this purpose involves the decomposition of Fe(CO)5 in decalin solvent as this reaction is strongly influenced by the cavitation conditions. Sonochemical treatment of this carbonyl results in the formation of amorphous Fe2O3, which on heat treatment gives nanocrystalline Fe2O3. It has been observed that concentration and power density parameters play an important role to obtain higher decomposition of Fe(CO)5 and hence higher yield of the amorphous Fe2O3 product. Also, using the experimentally observed results, a correlation (polynomial) has been developed.

The correlation in spatial intensity distribution between volumetric oscillation of multibubble and sonochemiluminescence in an ultrasonic standing-wave field is investigated through the measurements of scattered light from bubbles by changing the measuring position in the direction of sound propagation and sonochemiluminescence with luminol. When a thin light sheet, finer than half the wavelength of sound, is introduced into the cavitation bubbles at the anti-node of the sound pressure, the scattered light intensity oscillates temporally. The peak-to-peak light intensity corresponds to the number of the bubbles which contribute to the sonochemical reaction because the radius for oscillating bubbles at pressure antinode is restrictive in a certain range due to the shape instability and the action of Bjerknes force that expels from anti-node bubbles larger than the resonant size. The experimental results show that at the side near the water surface, the peak-to-peak light intensity is larger in comparison with the intensity near the sound source, and this tendency becomes apparent at higher input power. These light scattering results correspond with the spatial intensity distribution of the sonochemiluminescence with luminol. Therefore, it is interpreted that most of the cavitation bubbles contributing to the sonochemical reactions in the standing wave field exist near liquid surface. Present method of light scattering in reference with the image of the sonochemiluminescence is promising for evaluating spatial distribution of violently oscillating cavitation bubbles effective for sonochemical reactions.

Nanosized TiO2 supported on activated alumina was prepared using a sonochemical method. To prepare this supported material, direct immersion horn and cup horn ultrasonic systems were used. The efficiency of the sonochemical coating process was determined by UV photodecolourisation of the aqueous methyl orange solution. It was found that TiO2 supported on activated alumina prepared by the sonochemical method gave the maximum decolourisation efficiency. In that method itself, direct immersion horn gave a higher photodecolourisation activity as compared to the cup horn. The obtained results suggest that the direct immersion horn results in uniform, as well as a maximum number of TiO2 particles to be adsorbed on an activated alumina surface.

Sonochemical reactors offer excellent promise in the wastewater treatment applications due to the creation of local hotspots with overall ambient operating conditions and release of highly reactive free radicals. However, its application in the actual industrial practice is hampered by the fact that the existing available information related to the optimization of operating parameters is restricted mainly to small scale operations with reported experiments with capacity in the range of few milliliters to 1 l. With this information, efficient scale up and successful operation of industrial scale reactors is almost impossible. Thus, design of novel large-scale sonochemical reactors and subsequent testing of the same for destruction of different pollutants is the need of the present hour. In an attempt to move one step ahead in the design process, a novel sonochemical reactor with a capacity of 7.5 l has been developed and tested using destruction of Rhodamine B as a model reaction. Effect of various operating parameters such as frequency of irradiation, use of multiple frequencies and power dissipation into the system on the extent of degradation has been studied. Experiments have also been performed with the KI decomposition (model reaction typically used in investigating cavitational effects) so as to establish the dependency of the trends in the variation of the extent of degradation with the operating parameters on the cavitational intensity requirements for a specific application. For the degradation of Rhodamine B, power dissipation into the system was found to be the controlling parameter and the extent of degradation is directly proportional to the power dissipation with a coefficient of 74.1.

A novel method of treating a dye solution has been studied by hydrodynamic cavitation using multiple hole orifice plates. The present work deals with the effect of geometry of the multiple hole orifice plates on the degradation of a cationic dye rhodamine B (rhB) solution. The efficiency of this technique has been compared with the cavitation generated by ultrasound and it has been found that there is substantial enhancement in the extent of degradation of this dye solution using hydrodynamic cavitation. Large-scale operation coupled with better energy efficiency makes this technique a viable alternative for conventional cavitational reactors.

In order to assess the ultrasound dual frequency effects, sonochemical degradation of p-nitrophenol (p-NP) in an aqueous solution has been carried out with ultrasound at three operating frequencies, i.e., at 25, 40 kHz each independently, and the combination of two frequencies (25+40 kHz) simultaneously. Based on the rates of degradation, a kinetic study has been performed which leads to the evaluation of apparent kinetic rate constants for the degradation of p-NP. The influence of various parameters including initial solution pH, bulk solution temperature, on the degradation of p-NP was studied for these three frequency modes (25, 40 and 25+40 kHz) in order to investigate the temporal behaviour of this reaction, especially when it was operated in combined mode (25+40 kHz). The energy efficiency in the case of dual frequency mode is much better than single frequency modes. Modelling and cavity dynamics simulations have also been carried out to explain the observed effects. During combined mode operation, an improvement in the rate of degradation has been observed. The variation in the rate constants has been explained based on the difference in the acoustic pressure field in different systems including ultrasonic bath and dual frequency processor.

Acoustic and hydrodynamic cavitation can be used for a variety of applications ranging from biological applications such as cell disruption to chemical reactions such as oxidation of organic pollutants in aqueous effluents, including biorefractory toxic chemicals. Different equipment used for cavitational effects was compared based on a model reaction (decomposition of potassium iodide resulting into iodine liberation). A correlation was developed for the prediction of the cavitational yield in terms of the cavity collapse pressure. This correlation, when used with earlier correlations for the pressure amplitude generated during the violent collapse of cavities, will help design engineers to choose particular equipment, operating conditions, and geometric parameters to achieve a desired chemical change. The developed equation relating the macroscopic reaction rates with the collapse pressure is the first of its kind reported in the literature. Pilot-plant-scale hydrodynamic cavitation orifice plate setup is most energy-efficient, with significantly higher cavitational yields for the model reaction.

Enhancement of the reaction rate by combining the beneficial effects of PTC and ultrasound has been explored in the present study by taking the transformation of benzamide by dehydration to give benzonitrile as a model system. It was found that there is a substantial reduction in the reaction time when ultrasound was coupled with PTC.

An ultrasound mediated simple emulsion process has been demonstrated for the synthesis of zinc ferrite nanocrystals using the precursors of zinc and iron acetates and rapeseed oil. Following this technique avoids many of the outstanding problems that normally exist in conventional emulsion synthesis. Due to the simplicity of this process, it could also become a valuable starting point for the generation of other mixed and complex ferrites.

In this investigation, an attempt has been made to establish the physical mechanism of sonochemical synthesis of zinc ferrite with concurrent analysis of experimental results and simulations of cavitation bubble dynamics. Experiments have been conducted with mechanical stirring as well as under ultrasound irradiation with variation of pH and the static pressure of the reaction medium. Results of this study reveal that physical effects produced by transient cavitation bubbles play a crucial role in the chemical synthesis. Generation of high amplitude shock waves by transient cavitation bubbles manifest their effect through in situ micro-calcination of metal oxide particles (which are generated through thermal hydrolysis of metal acetates) due to energetic collisions between them. Micro-calcination of oxide particles can also occur in the thin liquid shell surrounding bubble interface, which gets heated up during transient collapse of bubbles. The sonochemical effect of production of OH radicals and H(2)O(2), in itself, is not able to yield ferrite. Moreover, as the in situ micro-calcination involves very small number of particles or even individual particles (as in intra-particle collisions), the agglomeration between resulting ferrite particles is negligible (as compared to external calcination in convention route), leading to ferrite particles of smaller size (6 nm).

Palladium catalyzed coupling of sulfinamide (II) with aryl halides gives sulfinated anilines which can be deprotected with HCl.

Coupling of aryl iodides bearing various functionalities including sensitive ones with alcohol (II) and subsequent silane cleavage allows the synthesis of substituted phenols under mild conditions.

In the present investigation, synthesis of manganese zinc ferrite (Mn(0.5)Zn(0.5)Fe(2)O(4)) nanoparticles with narrow size distribution have been prepared using ultrasound assisted emulsion (consisting of rapeseed oil as an oil phase and aqueous solution of Mn(2+), Zn(2+) and Fe(2+) acetates) and evaporation processes. The as-prepared ferrite was nanocrystalline. In order to remove the small amount of oil present on the surface of the ferrite, it was subjected to heat treatment at 300 °C for 3h. Both the as-prepared and heat treated ferrites have been characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), TGA/DTA, transmission electron microscopy (TEM) and energy dispersion X-ray spectroscopy (EDS) techniques. As-prepared ferrite is of 20 nm, whereas the heat treated ferrite shows the size of 33 nm. In addition, magnetic properties of the as-prepared as well as the heat treated ferrites have also been carried out and the results of which show that the spontaneous magnetization (σ(s)) of the heat treated sample (24.1 emu/g) is significantly higher than that of the as-synthesized sample (1.81 emu/g). The key features of this method are avoiding (a) the cumbersome conditions that exist in the conventional methods; (b) usage of necessary additive components (stabilizers or surfactants, precipitants) and (c) calcination requirements. In addition, rapeseed oil as an oil phase has been used for the first time, replacing the toxic and troublesome organic nonpolar solvents. As a whole, this simple straightforward sonochemical approach results in more phase pure system with improved magnetization.

Carbamic acid 2-trimethylsilylethyl ester (Teoc-NH 2 ) serves as an ammonia equivalent in the palladium-catalyzed amination of aryl bromides and aryl chlorides. Anilines with sensitive functional groups can be readily prepared using these amine derivatives.

Enhancement of the reaction rate by combining the beneficial effects of PTC and ultrasound has been explored in the present study by taking the transformation of benzamide by dehydration to give benzonitrile as a model system. It was found that there is a substantial reduction in the reaction time when ultrasound was coupled with PTC.

Using a standing wave sonochemical reactor (SWSR), the influences of parameters of ultrasonic power input, sonication time, sonication temperature and the amount of propanol (which generates the reducing radicals) were systemically investigated to ascertain and optimize the best conditions for the sonochemical reduction of Pt from its precursor hexachloroplatinic acid and then its deposition on rutile TiO(2) (platinization of rutile titania) catalysts. Catalytic activity of the prepared platinized catalysts was tested in the reaction of methyl orange degradation. The results of photocatalytic activity study in the degradation of methyl orange further demonstrate that sonochemically as-prepared Pt/TiO(2) catalysts show a pronounced increase ( approximately 2 times) in photodegradation, even with a deposition of small amounts of platinum (1.4wt.%), as compared to the unsupported or naked rutile titania. Although there are various parameters that influence the sonochemical platinization of rutile titania, the present optimization results clearly indicate that the best photocatalytic degradation of methyl orange can be obtained when the experimental conditions of the preparation were with an input power of 50W, an initial hexachloroplatinic acid volume of 70ml (which results into 1.4wt.% Pt on TiO(2)), sonication time of 90min, 0.18g of propanol and a temperature of 10 degrees C were adopted. The method of ultrasound application to prepare metal supported semiconductors has many advantages such as convenience, safety and high efficiency. Furthermore, it is hopeful that this optimization study can also be extended to the generation of similar metal supported semiconductors.

This paper addresses the physical features of the ultrasonic cavitational synthesis of zinc ferrite particles and tries to establish the relationship between cavitation physics and sonochemistry of the zinc ferrite synthesis. A dual approach of coupling experimental results with simulations of radial motion of cavitation bubbles has been adopted. The precursors for the zinc ferrite, viz. ZnO and Fe(3)O(4) are produced in situ by the hydrolysis of Zn and Fe(II) acetates stimulated by (*)OH radicals produced from the transient collapse of the cavitation bubbles. Experiments performed under different conditions create significant variation in the production of (*)OH radicals, and hence, the rate of acetate hydrolysis. Correlation of the results of experiments and simulations sheds light on the important facets of the physical mechanism of ultrasonic cavitational zinc ferrite synthesis. It is revealed that too much or too little rate of acetate hydrolysis results in smaller particle size of zinc ferrite. The first effect of a higher rate of hydrolysis leads to excessively large growth of particles, due to which they become susceptible to the disruptive action of cavitation bubbles. Whereas, the second effect of too small rate of hydrolysis of Zn and Fe(II) acetates restricts the growth of particles. It has been observed that the initial reactant concentration does not influence the mean particle size or the size distribution of zinc ferrite particles. The present investigation clearly confirms that the rate-controlling step of zinc ferrite synthesis through ultrasonic cavitational route is the rate of formation of (*)OH radicals from cavitation bubbles.

2-(Trimethylsilyl)ethanesulfonyl amide (SES-NH2) is an ammonia equivalent for the palladium-catalyzed amination of aryl bromides and aryl chlorides. Using these amine derivatives, it has been observed that anilines and anilines with sensitive functional groups can be readily prepared.

Solid Lipid Nanoparticles (SLN) containing Methotrexate (MTX), an anticancer drug for intravenous administration was formulated and characterized. The SLN dispersions with MTX, stearic acid, and soya lecithin in the ratio of 1:4:1, 1:4:1.5, and 1:4:2, sodium taurodeoxycholate and distilled water were prepared by micro emulsification solidification method. The results show that the prepared MTX-SLN particles (with MTX–Stearic acid–Soya lecithin—1:4:2) have an average size of 270 nm with 51.3% drug entrapment. The in vitro-release was attained up to 15th h. The pharmacokinetic studyreveals that the half-life and MRT of SLNs were higher than MTX solution. The life span of EAC (Ehrlich Ascite Carcinoma) bearing mice was increased when treated with MTX-SLNs (Methotrexate nanoparticles). These results clearly indicate that SLNs are a promising sustained release drug targeting system for lipophilic antitumour drugs.

The mechanism of the effect of particle addition on sonochemical reaction is studied through the measurements of frequency spectrum of sound intensity for evaluating the cavitation noise and the absorbance for the liberation of iodine from an aqueous solution of KI as an index of oxidation reaction by ultrasonic irradiation in the presence or absence of alumina particles. As it is expected that both the acoustic noise and a rise in temperature in the liquid irradiated by intense ultrasound will increase with the number of collapsing bubbles, these are supposed to be the best tools for evaluating the relative number of bubbles. In the present investigation, it has been shown that the addition of particles with appropriate amount and size results in an increase in the absorbance when both the acoustic noise and the rise in the liquid temperature due to cavitation bubbles also increase. This suggests that the enhancement in the yield of sonochemical reaction by appropriate particle addition comes from an increase in the number of cavitation bubbles. The existence of particle in liquid provides a nucleation site for cavitation bubble due to its surface roughness, leading to the decrease in the cavitation threshold responsible for the increase in the number of bubbles when the liquid is irradiated by ultrasound. Thus, from the present investigation, it is clarified that the particle addition has a potential to enhance the yield in the sonochemical reaction.

Ultrasound was irradiated to a micro-1D and -2D space having a characteristic length of 200 microm, and the presence of cavitation was confirmed from video images, and the generation of OH radicals, which was quantitatively evaluated with fluorometry.

In the present work hydrolysis of methyl benzoate was carried out using aqueous sodium hydroxide solution at room temperature in the presence of ultrasound since otherwise the same reaction takes place at relatively high temperature. Also, the above hydrolysis reaction was investigated at a relatively larger scale with the variation in parameters influencing the emulsification process and hence the reaction rates. It has been observed that the position of ultrasound source on the liquid–liquid interface is a crucial parameter affecting the two-phase emulsification rates. The poor bulk mixing occurring in the presence of ultrasound alone with an increase in the volume of the reaction mixture and its consequent effect on the reaction kinetics has been conclusively established. These studies have shown that the use of ultrasound with mechanical stirring can result in substantial reduction in the overall power consumption, especially for reaction systems like hydrolysis that do not require very high temperatures and pressures generated by cavitation.

Degradation of Rhodamine B, a waste water dye effluent was studied under the influence of ultrasound. In the present study, optimization of this degradation was carried out with power parameters, namely, power density (W/ml) and power intensity (W/cm2) using different ultrasonic equipments. From the studies, it has been observed that the degradation does not increase indefinitely with an increase in the power parameters, but instead, it reaches an optimum value and then decreases with a further increase in the power parameters. Also, these optima were not the same in all the ultrasonic equipments in which these studies were carried out. Difference in the type of acoustic field generated may be responsible for the different power optima observed with different ultrasonic equipments. The comparative study of the degradation of Rhodamine B using various ultrasonic equipments establishes a relationship between the area-specific parameter (intensity) and the volume-specific parameter (density) of reactivity.

Highly monodispersed submicron structures of ZnO were successfully fabricated by a simple ultrasonic cavitational activation, which assists a direct conversion of zinc acetate to ZnO, without using any additives.

Numerical simulations of bubble oscillations in liquid water irradiated by an ultrasonic wave are performed under the experimental condition for single-bubble sonochemistry reported by Didenko and Suslick [Nature (London) 418, 394 (2002)]. The calculated number of OH radicals dissolving into the surrounding liquid from the interior of the bubble agrees sufficiently with the experimental data. OH radicals created inside a bubble at the end of the bubble collapse gradually dissolve into the surrounding liquid during the contraction phase of an ultrasonic wave although about 30% of the total amount of OH radicals that dissolve into the liquid in one acoustic cycle dissolve in 0.1 micros at around the end of the collapse. The calculated results have indicated that the oxidant produced by a bubble is not only OH radical but also O atom and H2O2. It is suggested that an appreciable amount of O atom is produced by bubbles inside a standing-wave-type sonochemical reactor filled with water in which oxygen is dissolved as in the case of air.

The enhancement of sonochemical reactions by particle addition has been studied through the iodide liberation from an aqueous KI solution due to the oxidation reaction produced by ultrasound. The addition of particles causes an increase in the absorbance of I3−, and in addition, the noise due to cavitation bubbles also increases. The increase in the cavitation noise detected suggests that the addition of particles increases the number of cavitation bubbles thus enhancing the yield in the sonochemical reaction.