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Ultrasonic Irradiation (ultrasonic + irradiation)
Selected AbstractsChemInform Abstract: Facile Synthesis of 2-Amino-1,4-naphthoquinones Catalyzed by Molecular Iodine under Ultrasonic Irradiation.CHEMINFORM, Issue 37 2008Bing Liu Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] One-Pot and Solventless Synthesis of Ionic Liquids under Ultrasonic Irradiation.CHEMINFORM, Issue 52 2007Julien Estager Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Zinc-Mediated Allylation Reactions of Aldehydes and Ketones in Aqueous Media under Ultrasonic Irradiation.CHEMINFORM, Issue 41 2006Yan-Jiang Bian Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Novel Method for the Synthesis of Unsymmetrical Bis(indolyl)alkanes (III) Catalyzed by Ceric Ammonium Nitrate (CAN) under Ultrasonic Irradiation.CHEMINFORM, Issue 6 2006Xiao-Fei Zeng No abstract is available for this article. [source] Synthesis of Salicylic Acid Derivatives in Presence of Ultrasonic Irradiation Using Water as Solvent.CHEMINFORM, Issue 37 2003Maite L. Docampo Palacios Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Efficient and Selective Epoxidation of Alkenes by Supported Manganese Porphyrin under Ultrasonic Irradiation.CHEMINFORM, Issue 15 2001Valiollah Mirkhani Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Sonochemical synthesis and characterization of ZnO nanorod/Ag nanoparticle compositesCRYSTAL RESEARCH AND TECHNOLOGY, Issue 11 2009Fei Li Abstract A simple sonochemical route for the synthesis of Ag nanoparticles on ZnO nanorods is reported. Ultrasonic irradiation of a mixture of ZnO nanorods, Ag(NH3)2+, and formaldehyde in an aqueous medium yields ZnO nanorod/Ag nanoparticle composites. The powder X-ray diffraction of the ZnO/Ag composites shows additional diffraction peaks corresponding to the face-center-cubic structured Ag crystalline, apart from the signals from the ZnO nanorods. Scanning electron microscopy and transmission electron microscopy images of the ZnO/Ag composites reveal that the ZnO nanorods are coated with Ag nanoparticles with a mean size of several tens nanometer. The absorption band of ZnO/Ag composites is distinctly broadened and red-shifted, indicating the strong interfacial interaction between ZnO nanorods and Ag nanoparticles. This sonochemical method is simple, mild and readily scaled up, affording a simple way for synthesis of other composites. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effect of various extraction conditions on the phenolic contents of pomegranate seed oilEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 5 2008Hajar Abbasi Abstract Pomegranate seeds are byproducts of the pomegranate juice industry. Because of the presence of large amounts of certain pharmaceutical and nutraceutical components in the seeds, a proper extraction method to obtain these components is highly demanded in the food industry. In this study, the effect of different extraction methods on the total phenolic contents of the oil extracted from pomegranate seeds of the Malas variety from Shahreza, Iran, was investigated. Four different extraction methods including normal stirring, Soxhlet, microwave irradiation and ultrasonic irradiation using two types of organic solvents as well as a supercritical fluid extraction (SFE) method using CO2 as solvent were applied. The different organic solvents of this study did not indicate any significant differences in the total phenolic contents of the extracted oils, but the extracted oils from the various conditions of SFE indicated wide changes in the amount of phenolic compounds (7.8,72.1,mg/g). The total phenolic content of the extracted oil from one of the SFE runs was several times greater than those in the extracted oils using organic solvents. [source] Enhanced Antibacterial Activity of Nanocrystalline ZnO Due to Increased ROS-Mediated Cell InjuryADVANCED FUNCTIONAL MATERIALS, Issue 6 2009Guy Applerot Abstract An innovative study aimed at understanding the influence of the particle size of ZnO (from the microscale down to the nanoscale) on its antibacterial effect is reported herein. The antibacterial activity of ZnO has been found to be due to a reaction of the ZnO surface with water. Electron-spin resonance measurements reveal that aqueous suspensions of small nanoparticles of ZnO produce increased levels of reactive oxygen species, namely hydroxyl radicals. Interestingly, a remarkable enhancement of the oxidative stress, beyond the level yielded by the ZnO itself, is detected following the antibacterial treatment. Likewise, an exposure of bacteria to the small ZnO nanoparticles results in an increased cellular internalization of the nanoparticles and bacterial cell damage. An examination of the antibacterial effect is performed on two bacterial species: Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive). The nanocrystalline particles of ZnO are synthesized using ultrasonic irradiation, and the particle sizes are controlled using different solvents during the sonication process. Taken as a whole, it is apparent that the unique properties (i.e., small size and corresponding large specific surface area) of small nanometer-scale ZnO particles impose several effects that govern its antibacterial action. These effects are size dependent and do not exist in the range of microscale particles. [source] Study on bulk polymerization of methyl methacrylate initiated by low intensity ultrasonic irradiationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Sude Ma Abstract Methyl methacrylate (MMA) was polymerized in bulk solutions using low intensity ultrasonic radiation of 0.25 W/cm2. The polymerization occurred after 1 h of irradiation time was applied. The polymerization rate was greatly accelerated either by increasing the amount of poly (methyl methacrylate) (PMMA) granular added into the system or by elongating the irradiation time. However, it was found that the reaction rate increased with the decreasing of the ultrasonic frequencies when the exposure time of the polymerization under the irradiation was less than 3 h. Experimental results verified that the polymerization was initiated by free radicals, which were mainly generated from the degradation of PMMA macromolecular chains, the friction between the polymer macromolecular chains and the solvent monomer. These findings were obviously different from those obtained when high intensity ultrasonic irradiation was used. The polymers fabricated in this study by using ultrasound irradiation have a narrower molecular weight distribution compared to those obtained from the polymerizations induced by the conventional initiators. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Synthesis of 2-cyanoacrylates containing pyridinyl moiety under ultrasound irradiationJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 6 2005Huiping Zhang Reaction of ethyl cyanoacetate with carbon disulfide and dimethyl sulfate in the presence of sodium methoxide in anhydrous methanol yields ethyl 2-cyano-3,3-dimethyl- thioacrylate, followed by the nucle-ophilic substitution with 2-amino-3-chloro-4- methylpyridine under ultrasonic irradiation affording the key intermediate, ethyl 3-(2-chloro-4-methylpyridin-3-ylamino)-2-cyano-3-methylthioacrylate. The title compounds were then obtained through the reaction of the key intermediate with the aliphatic amine under reflux condition. All the new structures were verified by elemental analysis, IR, 1H NMR and mass spectra. In the MTT test, these new compounds were found to possess moderate antitumor activities against PC3 and A431 cells. [source] Relationship between the size of mist droplets and ethanol condensation efficiency at ultrasonic atomization on ethanol,water mixturesAICHE JOURNAL, Issue 3 2010Hitomi Kobara Abstract High-frequency (2.4 MHz) ultrasonic irradiation to an ethanol,water mixture can induce the generation of ethanol-rich mist droplets at lower temperatures. Two groups of droplets in micrometer- and nanometer-sized were observed in the mist generated by the ultrasonic atomization. Nanosized droplets were considered to be ethanol-rich droplets which cause ethanol condensation. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] An investigation of the mechanisms of ultrasonically enhanced desorptionAICHE JOURNAL, Issue 2 2007Oualid Hamdaoui Abstract In this work, the mechanisms underlying ultrasonic desorption of 4-chlorophenol from granular activated carbon have been explored. Desorption experiments are investigated in the absence and presence of 516 kHz ultrasound of different intensities. Using three regenerating solutions and two temperatures, it has been shown that ultrasonic irradiation considerably improves both the amount and the rate of desorption. Desorption increases with increasing temperature and ultrasound intensity. The addition of sodium hydroxide or a mixture of sodium hydroxide and ethanol to the regenerating medium leads to an enhancement of the desorption, especially in the presence of ultrasound. The mechanisms of ultrasonically enhanced desorption is due both to the thermal and non-thermal (hydrodynamical) effects of ultrasound. Hydrodynamical phenomena are principally produced by the acoustic vortex microstreaming within porous solids as well as at the solid-liquid interface and by the high-speed micro-jets and high-pressure shock waves produced by acoustic cavitation. The thermal effects are evaluated as localized hot spots formed when bubbles cavitated as well as by global heating of the medium and piezoelectric transducer heating-up. Additionally, the non-thermal effect of ultrasound is greater than the thermal effect, and it is more noticeable when the ultrasonic irradiation is carried out in a high temperature regenerating medium. © 2007 American Institute of Chemical Engineers AIChE J 2007 [source] Synthesis of block copolymers by combined ultrasonic irradiation and reverse atom transfer radical polymerization processesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 3 2004Mustafa Degirmenci Abstract A two-step procedure based on ultrasonic irradiation and reverse atom transfer radical polymerization (RATRP) for the synthesis of block copolymers is described. In the first step of the procedure, a stable chlorine-end-capped polymer is formed upon the ultrasonic irradiation of poly(methyl methacrylate) (PMMA) in dry benzene in the presence of a copper chloride/2,2,-bipyridine catalyst. Heating the system to 110 °C initiates the polymerization of the second monomer, styrene, and this results in the formation of the block copolymers. The degradation behavior of PMMA under ultrasonic irradiation has also been studied. The agreement of the experimentally obtained molecular weights and theoretical molecular weights and the unimodal shapes of the gel permeation chromatography curves of the block copolymers indicate the controlled nature of the RATRP process initiated by polymeric radicals formed by sonication. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 534,540, 2004 [source] Self-quenching in the electrochemiluminescence of Ru(bpy)32+ using ascorbic acid as co-reactantLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 3 2008Fumiki Takahashi Abstract In this study, electrochemiluminescence (ECL) of Ru(bpy)32+ (bpy = 2,2,-bipyridyl) using ascorbic acid (H2A) as co-reactant was investigated in an aqueous solution. When H2A was co-existent in a Ru(bpy)32+ -containing buffer solution, ECL peaks were observed at a potential corresponding to the oxidation of Ru(bpy)32+, and the intensity was proportional to H2A concentration at lower concentration levels. The formation of the excited state *Ru(bpy)32+ was confirmed to result from the co-reaction between Ru(bpy)33+and the intermediate of ascorbate anion radical (A,,), which showed the maximum ECL at pH = 8.8. It is our first finding that the ECL intensity would be quenched significantly when the concentration of H2A was relatively higher, or upon ultrasonic irradiation. In most instances, quenching is observed with four-fold excess of H2A over Ru(bpy)32+. The diffusional self-quenching scheme as well as the possible reaction pathways involved in the Ru(bpy)32+,H2A ECL system are discussed in this study. Copyright © 2008 John Wiley & Sons, Ltd. [source] Effect of surfactant type on the synthesis of PMMA using redox initiation and high frequency ultrasoundPOLYMER ENGINEERING & SCIENCE, Issue 10 2008Cristina Parra In the present work, a study of the effect of the surfactant nature on the synthesis of polymethylmethacrylate (PMMA) obtained by high frequency ultrasonic radiation and redox initiation is presented. The surfactants used were an anionic: sodium lauryl sulfate (SLS) and a nonionic: nonylphenol etoxilated. Different morphologies, particle size, and microstructures were obtained depending on the surfactant concentration (0.5, 1.0, 1.5, and 2.0)%. The highest conversion values of PMMA were obtained with SLS, resulting in a highly syndiotactic polymer. High frequency ultrasound is very efficient when ionic surfactants are used. However, for nonionic surfactants ultrasonic irradiation is very inefficient to initiate polymerization, in this case the effect of redox initiation was very marked increasing polymerization conversion. For this, surfactant blends of PMMA/PEO were obtained when redox initiation was used together with high frequency ultrasound. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers. [source] Micellar solutions of amphipathic copolymers based on carboxymethyl cellulosePOLYMER INTERNATIONAL, Issue 6 2003Ya Cao Abstract A novel family of amphipathic copolymers based on carboxymethyl cellulose (CM-cellulose) has been synthesized through ultrasonic irradiation. Their micellar conformation in aqueous solution was studied by dynamic laser scattering, environmental scanning electron microscopy and gel permeation chromatography. The results show that conformation of copolymer molecules is totally different from that of CM-cellulose because of the introduction of the surface active macromonomers. Due to the influence of hydrophobic character and molecular weight, different amphipathic copolymers have different micellar conformations, such as cylindrical, spheroidal or ellipsoidal micelles. In the range of concentration tested, the normalized first-order autocorrelation function g(1)(,) of a copolymer of CM-cellulose and poly(ethylene oxide) dodecyl ether acrylate does not fit a single-exponential decay, indicating a polydisperse system and the existence of species of different shapes and size. At different concentrations, the hydrodynamic radii of micelles (R) almost distribute into two regions of smaller and larger size. With increasing copolymer concentration, the region of smaller R remains in the range 30,100,nm and is considered to represent monomolecular micelles, while the larger R region increases gradually with concentration, which means that polymolecular micelles increase in size. © 2003 Society of Chemical Industry [source] Antibiotic glass slide coated with silver nanoparticles and its antimicrobial capabilitiesPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 11 2008Yaohui Lv Abstract Silver nanoparticles were covalently coated on a glass surface by overnight exposure of the glass substrate to nanoparticle solutions, using 3-aminopropyltriethoxysilane (APTES) as a coupling agent. Washing and air-drying yield a uniformly coated glass substrate, which can be used as a material capable of killing harmful microorganisms in food industry. Nanoparticles are stable on the glass surface and are not washed away by water; they even remain on the glass surface under short-term ultrasonic irradiation. The morphology of silver nanoparticles on the glass substrate was characterized by scanning electron microscope (SEM). The existence of Ag nanoparticles on the substrate was also confirmed by ultraviolet-visible (UV,Vis) spectroscopy. Fourier transform infrared (FT-IR) measurement shows that the connection is based on covalent bonds between silver nanoparticle surface/APTES molecules. Combining the effects of low cost and effectiveness in prohibiting the growth of Escherichia coli, such materials are expected to be used as antibacterial coatings, which may have large potential applications in food industry. Copyright © 2008 John Wiley & Sons, Ltd. [source] Degradation of the insecticides thiamethoxam and imidacloprid by zero-valent metals exposed to ultrasonic irradiation in water medium: electrospray ionization mass spectrometry monitoringRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 22 2008Renata P. Lopes The degradation of thiamethoxam (1) and imidacloprid (2), prototype neonicotinoid insecticides bearing a characteristic N-NO2 moiety in their structures, promoted by a number of zero-valent metals (Fe, Sn, Zn) upon ultrasonic irradiation in acidic aqueous solution (pH 2) was investigated. It was verified that thiamethoxam (1) and imidacloprid (2) are quickly and almost completely consumed under these experimental conditions (degradation >90% after a reaction time of 30,min) and that ultrasonic irradiation strongly enhances the degradation rate for both insecticides, especially when zinc and tin are employed. Based on the results from electrospray ionization mass (and tandem mass) spectrometry in the positive ion mode, degradation routes for both insecticides, comprising an initial NO2,,,NH2 reduction, were proposed. In addition, products from the dehydrochlorination of imidacloprid were also found to be formed under these conditions. Copyright © 2008 John Wiley & Sons, Ltd. [source] Effects of operating conditions on particle size in sonocrystallizationASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2010Hussein Oubani Abstract This work presents systematic investigations on sonocrystallization to elucidate the effects of key variables on sonocrystallization product properties. A novel continuous flow sonocrystallization apparatus was used to prepare NaCl microparticles from a NaCl,ethanol,water antisolvent system. By implementing a full factorial experimental design, we investigated the effects of ultrasonic power (75,225 W), antisolvent feed rate (0.5,6.5 l/h), system flow rate (2.8,4.1 l/min) and sonication time (5,30 min) on product crystal size. Data from these experiments were regressed to develop an empirical model that was found to be in agreement with experiments. The model identified the interaction between sonication power and system flow to be rather significant. Model simulations found that particle size decreases when antisolvent feed rate or ultrasonic power increases. This was found to be in contrast to increasing the system flow which resulted in larger particle sizes. The regression model was subsequently used to determine optimal operating conditions that minimize mean size, as smaller sizes are commonly required for pharmaceuticals such as for inhalation particles. These optimal values were found to be as follows: antisolvent flow rate = 6.5 l/h, power ultrasound = 225 W, system flow = 2.8 l/min and sampling time = 15 min. The optimal mean size predicted at these conditions was 28.6 ± 5.7 µm which is very close to the observed value of 27.6 µm. A high-speed camera was used to visualize the ultrasonic irradiation in the sonoreactor and was crucial in explaining the significant interactive effect of sonication power and system flow on crystal size. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Ultrasonically enhanced delivery and degradation of PAHs in a polymer,liquid partitioning system by a microbial consortiumBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2009Pedro A. Isaza Abstract The current study examined the effects of ultrasonic irradiation on mass transfer and degradation of PAHs, by an enriched consortium, when delivered from polymeric matrices. Rates of release into methanol under sonicated conditions, relative to unmixed cases, for phenanthrene, fluoranthene, pyrene, and benzo[a]pyrene were increased approximately fivefold, when delivered from Desmopan 9370 A (polyurethane). Similar effects were observed in Hytrel and Kraton® D4150 K polymers as well as recycled Bridgestone tires. Enhancements were also displayed as shifts to higher release equilibria under sonicated conditions, relative to non-sonicated cases, agreeing with current knowledge in sonochemistry and attributed to cavitation. Ultrasonic effects on microbial activity were also investigated and cell damage was found to be non- permanent with consortium re-growth being observed after sonic deactivation. Finally, the lumped effect of sonication on degradation of phenanthrene delivered from Desmopan was examined under the absence and presence of sonication. Rates of degradation were found to be increased by a factor of four demonstrating the possibility of using ultrasonic irradiation for improved mass transport in solid,liquid systems. Cellular inactivation effects were not evident, and this was attributed to the attenuation of sonic energy arising from the presence of solid polymer materials in the medium. The findings of the study demonstrate that sonication can be used to improve mass transport of poorly soluble compounds in microbial degradations, and alleviate limiting steps of soil remediation processes proposed in previous research. Biotechnol. Bioeng. 2009; 104: 91,101 © 2009 Wiley Periodicals, Inc. 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