Sonochemical hot spot

Suslick, Kenneth S.; Hammerton, D. A.; Cline, Raymond E.

doi:10.1021/ja00278a055

Cited by 1,153 publications

(544 citation statements)

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“…[100] In the case of non-volatile precursors, a 200 nm liquid phase ring surrounding the collapsing bubble is in charge of housing the reaction. [101] The macrostream produced due to collapse of bubbles creates a relatively uniform reaction condition for atomic mixing in the synthesis process. [102] Kim et al performed a sonochemical synthesis of superparamagnetic iron oxide nanoparticles coated by oleic acid and with high crystallinity.…”

Section: Sonochemistrymentioning

confidence: 99%

Synthesis, Functionalization, and Design of Magnetic Nanoparticles for Theranostic Applications

Mosayebi

Kiyasatfar

Laurent

2017

Adv Healthcare Materials

185

164

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In order to translate nanotechnology into medical practice, magnetic nanoparticles (MNPs) have been presented as a class of non‐invasive nanomaterials for numerous biomedical applications. In particular, MNPs have opened a door for simultaneous diagnosis and brisk treatment of diseases in the form of theranostic agents. This review highlights the recent advances in preparation and utilization of MNPs from the synthesis and functionalization steps to the final design consideration in evading the body immune system for therapeutic and diagnostic applications with addressing the most recent examples of the literature in each section. This study provides a conceptual framework of a wide range of synthetic routes classified mainly as wet chemistry, state‐of‐the‐art microfluidic reactors, and biogenic routes, along with the most popular coating materials to stabilize resultant MNPs. Additionally, key aspects of prolonging the half‐life of MNPs via overcoming the sequential biological barriers are covered through unraveling the biophysical interactions at the bio–nano interface and giving a set of criteria to efficiently modulate MNPs' physicochemical properties. Furthermore, concepts of passive and active targeting for successful cell internalization, by respectively exploiting the unique properties of cancers and novel targeting ligands are described in detail. Finally, this study extensively covers the recent developments in magnetic drug targeting and hyperthermia as therapeutic applications of MNPs. In addition, multi‐modal imaging via fusion of magnetic resonance imaging, and also innovative magnetic particle imaging with other imaging techniques for early diagnosis of diseases are extensively provided.

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Section: Sonochemistrymentioning

confidence: 99%

Synthesis, Functionalization, and Design of Magnetic Nanoparticles for Theranostic Applications

Mosayebi

Kiyasatfar

Laurent

2017

Adv Healthcare Materials

185

164

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“…Para avaliar a taxa de produção de oxidante pela degradação sonoquímica de CCl 4 , 4,00 mL de água e de solução saturada de CCl 4 foram sonicadas por até 50 s, para posterior mistura com 1,00 mL de solução 40 mg L -1 Fe 2+ . Experimentos foram também realizados, sonicando 4,00 mL de água e solução de CCl 4 com 1,00 mL da mesma solução de Fe 2+ .…”

Section: Procedimentosunclassified

“…Equações semi-empíricas para cálculos da quantidade de matéria (Q, mmol) consumida de Fe 2+ e produzida de H + com o tempo de sonicação para os diferentes sistemas irradiados. 4 . Desta forma, para intervalos de tempo de sonicação maiores, da ordem de centenas de segundos, seria esperada uma brusca queda na taxa de geração de radicais.…”

Section: Taxa De Formação De Oxidantesunclassified

“…Nos estudos realizados pôde ser constatado que reações de oxidação conduzidas pela sonicação de solução aquosa de CCl 4 apresentaram maior rendimento que aquelas com água. Possivelmente pela maior quantidade de radicais livres produzidos durante a sonólise do CCl 4 .…”

Section: Conclusõesunclassified

“…Na etapa de compressão os gases e vapores não retornam completamente para o líquido, resultando em aumento efetivo do tamanho da cavidade durante os ciclos seguintes de compressão e expansão até que seja atingido seu diâmetro crítico, entrando em violento colapso 2 . O colapso das bolhas transientes provoca a liberação de grande quantidade de energia, gerando temperaturas locais instantâneas muito elevadas (5200 K) e pressões da ordem de centenas de atmosferas 3,4 .…”

Section: Introductionunclassified

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Geração sonoquímica de oxidantes em solução aquosa saturada de tetracloreto de carbono

Borges¹,

Korn²

2002

Quím. Nova

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Recebido em 11/6/01; aceito em 8/11/01 SONOCHEMICAL PRODUCTION OF OXIDIZING SPECIES IN WATER SOLUTION SATURATED WITH CARBON TETRACHLORIDE. In this work the CCl 4 degradation in aqueous solution by sonication with 40 kHz commercial ultrasonic bath was investigated. Sonochemical degradation of CCl 4 occur by the cleavage of C-Cl bond into the cavitation bubbles. Oxidation reactions and the pH decreasing in the bulk solution during sonication were attributed to chlorine radicals produced by CCl 4 sonolysis, leading to increase the chloride concentration. The formation of oxidizing agents was evaluated employing I -and Fe 2+ ion solutions, converted to I 2 and HIO, and Fe 3+ , respectively. The amount of chloride and hydronium ions produced after 3 min of irradiation was 11.52 and 12.19 mmol, respectively, suggesting that the same reaction was involved to produce these ions. Fe 2+ oxidation and the pH variation were monitored to estimate chlorine radical formation rate in the presence (0.107 mmol s -1 ) and absence (0.092 mmol s -1 ) of metallic ion during the first minute of sonication.Keywords: sonochemical reactions; oxidizing species generation; carbon tetrachloride sonolysis. INTRODUÇÃOOs efeitos químicos provocados pelos ultra-sons ocorrem devido ao fenômeno da cavitação acústica, que é o processo de nucleação, crescimento e colapso de bolhas transientes em líquidos expostos a ondas ultra-sônicas de baixa frequência (< 1 MHz) 1 . As ondas ultrasônicas se propagam através de um líquido em ciclos alternados de compressão e expansão, porém, caso a onda acústica tenha pressão suficientemente alta, pode vencer as forças intermoleculares num ponto do líquido, criando uma cavidade para a qual podem se difundir, durante a etapa de expansão, os gases e vapores presentes no líquido. Na etapa de compressão os gases e vapores não retornam completamente para o líquido, resultando em aumento efetivo do tamanho da cavidade durante os ciclos seguintes de compressão e expansão até que seja atingido seu diâmetro crítico, entrando em violento colapso 2 . O colapso das bolhas transientes provoca a liberação de grande quantidade de energia, gerando temperaturas locais instantâneas muito elevadas (5200 K) e pressões da ordem de centenas de atmosferas 3,4 .O processo de cavitação e as temperaturas geradas no colapso são fortemente dependentes da pressão de vapor do solvente. Assim, moléculas de solventes com altas pressões de vapor (e.g. moléculas de água) podem penetrar nas cavidades e, no momento do colapso, sofrerem sonólise, resultando na formação de novos produtos (e.g. H 2 e H 2 O 2 ).Propriedades físico-químicas dos gases dissolvidos (condutividade térmica, capacidade calorífica, pressão parcial e solubilidade no solvente) garantirão a eficiência da cavitação e, conseqüentemen-te, da sonólise 5,6 . Em outra aproximação, sabe-se que a eficiência de cavitação depende da freqüência e amplitude das ondas acústicas, potência do sonicador, bem como da tensão superficial, força iônica e temperatura do meio solvente 7 . Também, a pre...

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Ultrasonically initiated free radical-catalyzed emulsion polymerization of methyl methacrylate (i)

Chou

Stoffer

1999

J. Appl. Polym. Sci.

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SYNOPSIS:The emulsion polymerization of methyl methacrylate initiated by ultrasound has been studied at ambient temperature using sodium lauryl sulfate as the surfactant. The investigation includes the: (1) nature and source of the free radical for the initiation process; (2) effects of different types of cavitation; and (3) dependence of the polymerization rate, polymer particle number generated, and the polymer molecular weight on acoustic intensity, argon gas flow rate, surfactant concentration, and initial monomer concentration. It was found that the polymerization could be initiated by ultrasound in the emulsion systems containing methyl methacrylate, water, and sodium lauryl sulfate at ambient temperature in the absence of a conventional initiator. The source of the free radical for the initiation process was found to come from the degradation of the sodium lauryl sulfate, presumably in the aqueous phase. The weight average molecular weight of the poly(methyl methacrylate) obtained varied from 2,500,000 to 3,500,000 g mol Ϫ1, and the conversion for polymerization was up to 70%. Deviations from the Smith-Ewart kinetics were observed. The polymerization rate was found to be proportional to the acoustic intensity to the 0.98 power; to the argon gas flow rate to the 0.086 power; to the surfactant concentration to the 0.08 power, with the 0.035M-0.139M surfactant concentration range; and to the surfactant concentration to the 0.58 power, with the 0.139M-0.243M surfactant concentration range. The polymerization rate was found to increase with increasing initial monomer concentration up to a point where it became independent of initial monomer concentration. The polymer particle number generated per milliliter of water was found to be proportional to the acoustic intensity to the 1.23 power; to the argon gas flow rate to the 0.16 power; to the surfactant concentration to the 0.3 power, with the 0.035M-0.139M surfactant concentration range; and to the surfactant concentration to the 1.87 power, with the 0.139M-0.243M surfactant concentration range. The polymer weight average molecular weight was found to be proportional to the acoustic intensity to the 0.21 power, and to the argon gas flow rate to the 0.02 power. It was found to be inversely proportional to the surfactant concentration to the 0.12 and 0.34 power, with the 0.035M-0.139M and the 0.139M-0.243M surfactant concentration ranges, respectively. The polymer yield and polymerization rate were found to be much larger than those obtained from an ultrasonically initiated bulk polymerization method. The polymerization rates obtained at ambient temperature were found to be similar to or higher than those obtained from the conventional higher temperature thermal emulsion polymerization method. This investigation demonstrated the capability of ultrasound to both initiate and accelerate polymerization in the emulsion system, and to do this at a lower temperature that could offer substantial energy savings.

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Sonochemical hot spot

Cited by 1,153 publications

References 0 publications

Synthesis, Functionalization, and Design of Magnetic Nanoparticles for Theranostic Applications

Synthesis, Functionalization, and Design of Magnetic Nanoparticles for Theranostic Applications

Geração sonoquímica de oxidantes em solução aquosa saturada de tetracloreto de carbono

Ultrasonically initiated free radical-catalyzed emulsion polymerization of methyl methacrylate (i)

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