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Encapsulation is the process of stabilization of active compounds through the structuring of systems capable of preserving their chemical, physical, and biological properties, x their release or delivery under established or desired conditions In the process of encapsulation, either one or the mixture of bioactive material is coated with another single material or combination of materials. In encapsulation, two main terminologies are frequently used. One is the material that is being coated is termed active material or core material, and the other is the shell material that is also termed carrier material (shell). The shell material can be in solid, liquid droplets, and gas bubbles to encapsulate liquid or gas inside as a core. The core and shell structure can be in various shapes such as the sphere, microcapsules, microbeads, monocore, multicore, matrix, and multishell.

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.

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 investigation focuses in investigating the effect of osmotic pressure, gelling on the mean droplet diameter, polydispersity index, droplet size stability of the developed novel Aspirin containing water-in-oil-in-water (W/O/W) nano multiple emulsion. The aspirin-loaded nano multiple emulsion formulation was successfully generated using two-stage ultrasonic cavitational emulsification which had been reported in author's previous study. The osmotic behavior of ultrasonically prepared nano multiple emulsions were also examined with different glucose concentrations both in the inner and outer aqueous phases. In addition, introducing gelatin into the formulation also observed to play an important role in preventing the interdroplet coalescence via the formation of interfacial rigid film. Detailed studies were also made on the possible mechanisms of water migration under osmotic gradient which primarily caused by the permeation of glucose. Besides, the experimental results have shown that the interfacial tension between the two immiscible phases decreases with varying the composition of organic phase. Although the W/O/W emulsion prepared with the inner/outer glucose weight ratio of 1-0.5% (w/w) showed an excellent droplet stability, the formulation containing 0.5% (w/w) glucose in the inner aqueous phase appeared to be the most stable with minimum change in the mean droplet size upon one-week storage period. Based on the optimization, nano multiple emulsion droplets with the mean droplet diameter of around 400 nm were produced using 1.25% (w/w) Span 80 and 0.5% Cremophore EL. Overall, our investigation makes a pathway in proving that the use of ultrasound cavitation is an efficient yet promising approach in the generation of stable and uniform nano multiple emulsions and could be used in the encapsulation of various active pharmaceutical ingredients in the near future.

Ferrous fumarate, [C4H2FeO4] is widely utilized in the effective treatments and prevention of iron deficiency anemia. But, its administration has been oftentimes linked with quite a few side effects than ferric products. To overcome the side effects, multiple water-in-oil-in-water (W/O/W) emulsion formulations had been proposed as a new drug delivery system for the controlled release of entrapped active iron compound. In this study, high-pressure liquid whistle hydrodynamic cavitation reactor has been developed to produce highly stable W/O/W multiple emulsions containing Ferrous Fumarate in submicron scale (∼600 nm) with the droplet-size distribution polydispersity index in the narrow regime (0.35–0.40). The microscopic observations confirmed that that the physical stability of the W/O/W emulsions was increased significantly with operating pressure and number of emulsification passes. Looking at the potential for scale-up, this could be a promising technique to produce multiple emulsions incorporated with active constituents. © 2012 American Institute of Chemical Engineers AIChE J, 59: 155–167, 2013

The main goal of the present work was to develop a novel aspirin containing water-in-oil-in-water (W/O/W)-type submicron multiple emulsions via two-stage ultrasound cavitational emulsification using Span 80 and Cremophor EL as lipophilic and hydrophilic emulsifiers for the formation of primary and secondary emulsions, respectively. Effect of the following parameters, i.e. concentration of emulsifiers, ultrasonic amplitude and second sonication period on the mean droplet diameter, polydispersity index, droplet size stability and drug entrapment efficiency was studied. The osmotic behavior of the ultrasonically prepared multiple emulsions was also studied with different glucose concentrations in the inner and outer aqueous phases. The presence of gelatin played an important role in preventing interdroplet coalescence via formation of interfacial rigid film. Core shell type of multiple droplets with mean droplet diameter of around 400 nm was produced using 1.25% w/w Span 80 and 0.5% w/w Cremophor EL. The experimental results have shown that the long-term stability of the W/O/W multiple emulsions is significantly improved with the addition of both 0.5% w/w of glucose and 1% w/w of gelatin in the inner phase. This investigation has clearly proved that the use of ultrasound cavitation is an efficient yet promising approach in the generation of stable and uniform submicron multiple emulsions of aspirin. Copyright © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.

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.

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.

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.

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.

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).

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.

Fine particles of rutile TiO2 supporting nanosized particles of Pt were prepared by a simultaneous in situ sonochemical reduction and deposition method using a standing wave sonochemical reactor (SWSR). The mean diameter of sonochemically obtained Pt particles are of 2 nm. Following this sonochemical technique, rutile TiO2 was also deposited with different weight percentages of Pt. Catalytic function of the prepared composite catalysts were tested by the oxidation of CO to CO(2). From the catalytic activity results, it has been found out that the catalysts prepared by the sonochemical method exhibited higher catalytic activity for CO oxidation, probably attributed to the higher Pt particle distribution achieved under sonication. Transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), and diffuse reflectance spectroscopy (DRS) were employed to characterize the resulting material.

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.