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Muthupandian Ashokkumar - One of the best experts on this subject based on the ideXlab platform.

  • physical and Chemical Effects of acoustic cavitation in selected ultrasonic cleaning applications
    Ultrasonics Sonochemistry, 2016
    Co-Authors: Muthupandian Ashokkumar, Nor Saadah M Yusof, Bandar A Babgi, Yousef Gamaan Alghamdi, Mecit Aksu, J Madhavan
    Abstract:

    Acoustic cavitation in a liquid medium generates several physical and Chemical Effects. The oscillation and collapse of cavitation bubbles, driven at low ultrasonic frequencies (e.g., 20 kHz), can generate strong shear forces, microjets, microstreaming and shockwaves. Such strong physical forces have been used in cleaning and flux improvement of ultrafiltration processes. These physical Effects have also been shown to deactivate pathogens. The efficiency of deactivation of pathogens is not only dependent on ultrasonic experimental parameters, but also on the properties of the pathogens themselves. Bacteria with thick shell wall are found to be resistant to ultrasonic deactivation process. Some evidence does suggest that the Chemical Effects (radicals) of acoustic cavitation are also effective in deactivating pathogens. Another aspect of cleaning, namely, purification of water contaminated with organic and inorganic pollutants, has also been discussed in detail. Strong oxidising agents produced within acoustic cavitation bubbles could be used to degrade organic pollutants and convert toxic inorganic pollutants to less harmful substances. The effect of ultrasonic frequency and surface activity of solutes on the sonoChemical degradation efficiency has also been discussed in this overview.

  • The Physical and Chemical Effects of Ultrasound
    Food Engineering Series, 2010
    Co-Authors: Sandra E. Kentish, Muthupandian Ashokkumar
    Abstract:

    Ultrasound refers to sound waves above the human hearing range. The physical Effects of ultrasound include the turbulence associated with cavitational bubble collapse, microjetting, and the streaming movement of cavitational microbubbles to the pressure antinodes of a standing wave field. These physical Effects are strongest near to fluid/solid and fluid/fluid boundaries, which mean that ultrasound is extremely effective in enhancing heat and mass transfer within such boundary layers. Chemical Effects arise from free radical production during transient cavitational collapse of bubbles.

Huilin Li - One of the best experts on this subject based on the ideXlab platform.

  • physical and Chemical Effects of ultrasound vibration on polymer melt in extrusion
    Ultrasonics Sonochemistry, 2010
    Co-Authors: Jinyao Chen, Yingzi Chen, Huilin Li
    Abstract:

    The physical and Chemical Effects of ultrasound on polypropylene (PP) melts in extrusion were investigated. By applying ultrasound vibration to the entrance of the die, apparent pressure and viscosity of PP can be obviously decreased under the appropriate ultrasound power. Ultrasound has both physical and Chemical Effects on the polymer melt. In our study with specific polymer and ultrasound system, we determined that the Chemical effect makes up 35-40% of the total effect of ultrasound on the apparent viscosity reduction of PP melts at most of the studied intensities. The physical effect plays a more important role in the ultrasound-applied extrusion than the Chemical effect. This Chemical effect is an irreversible and permanent change in molecule weight and the molecular-weight distribution due to ultrasound. As the ultrasound intensity increases, the molecular weight of PP reduces and its molecular-weight distribution becomes narrower; the orientation of PP molecules along the flow direction reduces (in melt state) and the crystallinity of PP samples (in solid state) decreases by applying the ultrasound vibration. Ultrasound vibration increases the motion of molecular chains and makes them more disorder; it also affects the relaxation process of polymer melts by shortening the relaxation time of chain segments, leading to weakening the elastic effect and decreasing the extruding swell ratios. All the factors discussed above reduce the non-Newtonian flow characteristics of the polymer melt and result in the viscosity drop of the polymer melt in extrusion.

Hisashi Hayashi - One of the best experts on this subject based on the ideXlab platform.

  • Chemical Effects of Lγ4 emission spectra
    Journal of Electron Spectroscopy and Related Phenomena, 2014
    Co-Authors: Hisashi Hayashi
    Abstract:

    Abstract An overview of the Chemical Effects of the Lγ4 (L1O2,3) emission of Ce, Sm, Eu, and Yb is reported. The Lγ4 emission spectra differ significantly depending on the Chemical environment of the lanthanides. The emission from the early lanthanide Ce is ligand-dependent, whereas the emission from the middle lanthanides, Sm and Eu, is valence-dependent with Chemical shifts of 4–5 eV. The emission from the late lanthanide Yb, which exhibits Lγ4 and Lγ4' bands, depends on both the valency and the coordination environment. Thus, Lγ4 emission is a potentially useful probe that can be used to evaluate the Chemical states of lanthanides, in particular, the oxidation numbers of middle to late lanthanides in mixed-valence compounds.

  • Chemical Effects of CeLγ4 Emission Spectra for Ce Compounds
    Analytical sciences : the international journal of the Japan Society for Analytical Chemistry, 2010
    Co-Authors: Hisashi Hayashi, Yuki Takehara, Naomi Kawamura, Masaichiro Mizumaki
    Abstract:

    High-resolution CeLγ4 emission spectra of CeF3, Ce2S3, CeF4, and CeO2 have been measured using a multicrystal, multidetector spectrometer. The spectra exhibited substantial differences depending on the Chemical environment of the Ce ions. By comparing the observed CeO2 spectrum with the band calculations, we determined that the observed Chemical Effects of the main emission line were primarily attributable to the transitions of the Ce5p band; the high-energy tail at around 6.539 keV was assigned to the ligand p→Ce2s cross transition. Further, a key difference between CeLγ4 and EuLγ4 is discussed with reference to CeL1- and EuL1-X-ray absorption fine-structures (XAFS). Possible applications of CeLγ4 emissions to material characterization are also suggested.

  • Chemical Effects on valence→ L emissions of lanthanide compounds
    Spectrochimica Acta Part B: Atomic Spectroscopy, 2009
    Co-Authors: Hisashi Hayashi, Kyoko Okada
    Abstract:

    Abstract Ce L β emission spectra of CeF 3 and CeO 2 have been measured with energy resolution of ~ 3 eV by a wave-dispersive spectrometer. The observed Ce L β 7 band shows certain difference between the two compounds both in profile and intensity. The Chemical Effects can be reproduced by a band calculation using WIEN2k, which suggests that the Ce L β 7 reflects valence-band structure of compounds, and therefore, is hopeful as a probe of selective X-ray absorption fine structure.

  • Encyclopedia of Analytical Chemistry - Chemical Effects in Hard X‐ray Photon‐In Photon‐Out Spectra
    Encyclopedia of Analytical Chemistry, 2000
    Co-Authors: Hisashi Hayashi
    Abstract:

    Hard X-ray photon-in photon-out techniques are targeted at applications where the sample environment cannot be freely chosen. The resultant X-ray emission spectra are influenced by the Chemical environments of the atoms involved. If high-resolution measurements are possible, the Chemical Effects in the X-ray emission spectra can provide information about the Chemical states, complementary to that offered by other X-ray spectroscopies. X-ray emission is classified into six categories for convenience: X-ray diagram lines, X-ray valence-band emission, radiative Auger effect, resonant X-ray emission, Compton scattering, and X-ray Raman scattering. After a brief description of the history of research on these types of emission, the Chemical Effects that they reveal and related topics, including high-resolution absorption measurements and the static structure factor, are reviewed. An overview of the instrumentation employed in both laboratories and synchrotron radiation (SR) facilities is also given.

Arnim Henglein - One of the best experts on this subject based on the ideXlab platform.

  • Chemical Effects of continuous and pulsed ultrasound in aqueous solutions
    Ultrasonics Sonochemistry, 1995
    Co-Authors: Arnim Henglein
    Abstract:

    Abstract Molecules dissolved in water can undergo pyrolysis and free radical attack when cavitation is produced by ultrasound. Macromolecules are also degraded in the main chain. The yields of these processes depend on the volatility and hydrophobicity of the solutes and on the nature of the gas in the solution. The Effects of 1 MHz (quartz) and 20 kHz (horn) are compared; the yield ratio of oxidation to mechanical degradation is strongly dependent on the cavitation conditions. Chemical Effects produced by pulsed ultrasound are also described and compared with Effects observed in continuous irradiation experiments.

Dong Liu - One of the best experts on this subject based on the ideXlab platform.

  • Coupled Chemical Effects of carbon dioxide and hydrogen additions on premixed lean dimethyl ether flames
    Science China Technological Sciences, 2016
    Co-Authors: Wei Pan, Dong Liu
    Abstract:

    Kinetic analysis of coupled Effects of CO2 and H2 additions on laminar lean premixed dimethyl ether flames is performed at atmospheric pressure. The coupled Effects of H2/CO2 additions on major species, intermediate stable species and radicals are discussed and analyzed in detail. The dilution, thermal and Chemical Effects of H2 and CO2 are separated and identified. The results show that H2 addition can slightly mitigate the CO2 Chemical Effects on decreasing the temperatures, H radical concentration, acetylene mole fraction and formaldehyde concentration. After CO2 is added, the H2 Chemical Effects on increasing the temperatures are enhanced. DME oxidation is promoted by the H2 Chemical Effects, which is further strengthened by the CO2 addition. Moreover, CO2 addition can reduce the H2 Chemical Effects on increasing the H radical mole fraction, but strengthen the H2 Chemical Effects on increasing the production of HO2 and C2H2. CH2O formation can be promoted by the H2 Chemical Effects, which is enhanced by the CO2 addition. In actually, the H2/CO2 coupled Chemical Effects almost have no obvious influence on the temperatures and HO2 mole fraction. DME consumption is delayed by the H2/CO2 coupled Chemical Effects. Furthermore, the H2/CO2 coupled Chemical Effects can decrease the H radical mole fraction, CH4 concentration, C2H2 mole fraction, CH2O concentration and CH3CHO mole fraction, but increase the CO concentration.

  • Chemical Effects of Carbon Dioxide Addition on Dimethyl Ether and Ethanol Flames: A Comparative Study
    Energy & Fuels, 2015
    Co-Authors: Dong Liu
    Abstract:

    The Chemical Effects of CO2 addition on premixed laminar low-pressure dimethyl ether and ethanol flames were studied by comprehensive numerical analysis from fuel-lean to fuel-rich conditions. Added CO2 is assumed as normal reactive CO2 and fictitious inert CO2 to assess the Chemical Effects of CO2. The dilution and thermal Effects of CO2 addition decrease C2H2 mole fractions in ethanol flames instead of DME flames, but the Chemical Effects can reduce C2H2 mole fractions in both DME and ethanol flames at all equivalence ratios, which reveals that C2H2 formation can be suppressed Chemically by CO2 addition. The Chemical Effects have a weak influence on formaldehyde formation in both DME and ethanol flames. The CO2 Chemical Effects only result in a slight decrease of acetaldehyde peak mole fractions in DME flames but not in ethanol flames at all equivalence ratios. Mole fractions of the H radical decrease because of the Chemical Effects of CO2 addition by shifting the equilibrium of CO + OH = CO2 + H in bot...

  • detailed influences of Chemical Effects of hydrogen as fuel additive on methane flame
    International Journal of Hydrogen Energy, 2015
    Co-Authors: Yaoyao Ying, Dong Liu
    Abstract:

    Abstract A detailed kinetic analysis of Chemical Effects of hydrogen addition on laminar premixed stoichiometric methane-air flames was conducted at atmospheric pressure. Flame structures and mole fraction profiles affected by Chemical Effects of hydrogen addition for major species, free radicals and intermediate species are analyzed with particular emphasis on the formations of soot precursor and oxygenated air pollutants. The results illustrate that Chemical Effects of hydrogen additive lead the methane profile to move towards the upstream side and suppress the formation of acetylene and ketene. The concentrations of free radical H, O and OH increase as methane is replaced by hydrogen mainly due to its Chemical Effects. In contrast, although the Chemical Effects of hydrogen addition facilitate the productions of formaldehyde and acetaldehyde, the hydrogen dilution and thermal Effects on reducing mole fractions of both species are more significant. As a consequence, the total Effects of hydrogen addition lead to a decrease in formaldehyde and acetaldehyde concentrations. Compared to formaldehyde and acetaldehyde, NO mole fraction diminishes in a similar fashion with increased hydrogen additive that the decrease of NO concentration caused by hydrogen dilution and thermal Effects is larger than the increase due to its Chemical Effects.

  • Kinetic analysis of the Chemical Effects of hydrogen addition on dimethyl ether flames
    International Journal of Hydrogen Energy, 2014
    Co-Authors: Dong Liu
    Abstract:

    Abstract The Chemical Effects of hydrogen addition on premixed laminar low-pressure dimethyl ether flames were studied by kinetic analysis. The Chemical Effects of hydrogen addition on flame structures and mole fractions of major species, intermediate species and free radicals have been distinguished clearly from the dilution and thermal Effects. The results show that the Chemical Effects of hydrogen addition cause the DME profile to move toward the upstream side and can suppress the production of acetylene and ethylene. The production of formaldehyde is promoted by the Chemical Effects of hydrogen addition but the dilution and thermal Effects are more dominant which decrease the mole fraction of formaldehyde so that the overall Effects make formaldehyde mole fraction decrease. The dominant Effects of hydrogen addition on H, OH and O radicals are the Chemical Effects that make mole fractions of these radicals increase.