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Goodson III, William H.,Lowe, Leroy,Carpenter, David O.,Gilbertson, Michael,Manaf Ali, Abdul,Lopez de Cerain Salsamendi, Adela,Lasfar, Ahmed,Carnero, Amancio,Azqueta, Amaya,Amedei, Amedeo,Charles, Ame Oxford University Press 2015 Carcinogenesis Vol.36 No.suppl1
<P>Lifestyle factors are responsible for a considerable portion of cancer incidence worldwide, but credible estimates from the World Health Organization and the International Agency for Research on Cancer (IARC) suggest that the fraction of cancers attributable to toxic environmental exposures is between 7% and 19%. To explore the hypothesis that low-dose exposures to mixtures of chemicals in the environment may be combining to contribute to environmental carcinogenesis, we reviewed 11 hallmark phenotypes of cancer, multiple priority target sites for disruption in each area and prototypical chemical disruptors for all targets, this included dose-response characterizations, evidence of low-dose effects and cross-hallmark effects for all targets and chemicals. In total, 85 examples of chemicals were reviewed for actions on key pathways/mechanisms related to carcinogenesis. Only 15% (13/85) were found to have evidence of a dose-response threshold, whereas 59% (50/85) exerted low-dose effects. No dose-response information was found for the remaining 26% (22/85). Our analysis suggests that the cumulative effects of individual (non-carcinogenic) chemicals acting on different pathways, and a variety of related systems, organs, tissues and cells could plausibly conspire to produce carcinogenic synergies. Additional basic research on carcinogenesis and research focused on low-dose effects of chemical mixtures needs to be rigorously pursued before the merits of this hypothesis can be further advanced. However, the structure of the World Health Organization International Programme on Chemical Safety ‘Mode of Action’ framework should be revisited as it has inherent weaknesses that are not fully aligned with our current understanding of cancer biology.</P>
이주현,윤용진,John K. Eaton,Kenneth E. Goodson,배성재 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.
Oxide and CNT nanoparticles were prepared and characterized to understand the effect of disaggregation on the thermal conductivityand viscosity of nanofluids through experimental and theoretical analysis. The oxide nanofluids contained spherical oxidenanoparticles, including Al2O3, CuO, and ZnO, and the CNT nanofluids contained multiwalled carbon nanotubes in deionized water. Aggregations of numerous oxide nanoparticles were observed from Dynamic Light Scattering and Scanning Electron Microscopy. Ultrasonication and centrifugation were made to mechanically separate the agglomerated nanoparticles. Nanoparticle size decreasedby 15% with one hour sonication for oxide nanoparticles with diameters in the range of 10~100 nm and centrifugation disaggregationmethods showed 36% and 40% reduction in size for the Al2O3/DI water and the CuO/DI water nanofluid, respectively. A chemicalbased disaggregation method for the oxide nanoparticles using surfactants and changing the pH were performed. A significant sizereduction was achieved with a pH value of 4.2. The effects of agglomeration on the thermal conductivity and viscosity of nanofluidswere examined based on the three-level homogenization model. The use of hydrodynamic particle nanofluid shows an effective thermalconductivity and viscosity, when the aspect ratio of the particle aggregation is below 4.1 and 2.5 for CuO/water and Al2O3/waternanofluid, respectively.
Optically Excited Acoustic Vibrations in Quantum-Sized Monolayer-Protected Gold Clusters
Varnavski, Oleg,Ramakrishna, Guda,Kim, Junhyung,Lee, Dongil,Goodson, Theodore American Chemical Society 2010 ACS NANO Vol.4 No.6
<P>We report a systematic investigation of the optically excited vibrations in monolayer-protected gold clusters capped with hexane thiolate as a function of the particle size in the range of 1.1−4 nm. The vibrations were excited and monitored in transient absorption experiments involving 50 fs light pulses. For small quantum-sized clusters (≤2.2 nm), the frequency of these vibrations has been found to be independent of cluster size, while for larger clusters (3 and 4 nm), we did not observe detectable optically excited vibrations in this regime. Possible mechanisms of excitation and detection of the vibrations in nanoclusters in the course of the transient absorption are discussed. The results of the current investigation support a displacive excitation mechanism associated with the presence of finite optical energy gap in the quantum-sized nanoclusters. Observed vibrations provide a new valuable diagnostic tool for the investigations of quantum size effects and structural studies in metal nanoclusters.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2010/ancac3.2010.4.issue-6/nn1003524/production/images/medium/nn-2010-003524_0007.gif'></P>
Lee, Joohyun,Yoon, Yong-Jin,Eaton, John K.,Goodson, Kenneth E.,Bai, Seoung Jai 한국정밀공학회 2014 International Journal of Precision Engineering and Vol.15 No.4
Oxide and CNT nanoparticles were prepared and characterized to understand the effect of disaggregation on the thermal conductivity and viscosity of nanofluids through experimental and theoretical analysis. The oxide nanofluids contained spherical oxide nanoparticles, including $Al_2O_3$, CuO, and ZnO, and the CNT nanofluids contained multiwalled carbon nanotubes in deionized water. Aggregations of numerous oxide nanoparticles were observed from Dynamic Light Scattering and Scanning Electron Microscopy. Ultrasonication and centrifugation were made to mechanically separate the agglomerated nanoparticles. Nanoparticle size decreased by 15% with one hour sonication for oxide nanoparticles with diameters in the range of 10~100 nm and centrifugation disaggregation methods showed 36% and 40% reduction in size for the $Al_2O_3$/DI water and the CuO/DI water nanofluid, respectively. A chemical based disaggregation method for the oxide nanoparticles using surfactants and changing the pH were performed. A significant size reduction was achieved with a pH value of 4.2. The effects of agglomeration on the thermal conductivity and viscosity of nanofluids were examined based on the three-level homogenization model. The use of hydrodynamic particle nanofluid shows an effective thermal conductivity and viscosity, when the aspect ratio of the particle aggregation is below 4.1 and 2.5 for CuO/water and $Al_2O_3$/water nanofluid, respectively.
Critical Size for the Observation of Quantum Confinement in Optically Excited Gold Clusters
Varnavski, Oleg,Ramakrishna, Guda,Kim, Junhyung,Lee, Dongil,Goodson, Theodore American Chemical Society 2010 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.132 No.1
<P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2010/jacsat.2010.132.issue-1/ja907984r/production/images/medium/ja-2009-07984r_0003.gif'> <P>We present a systematic study of optical properties of a series of hexanethiolate-capped Au clusters of varying sizes using femtosecond transient absorption, time-resolved fluorescence, and two-photon absorption cross-sectional measurements. An abrupt change in optical properties and their trends has been found at the 2.2 nm size. Displacively excited vibrations with a period of 450 fs have been detected in the transient absorption signal for smaller clusters ≤2.2 nm. These results strongly suggest an emerging optical gap between the highest occupied and lowest unoccupied orbitals in the narrow size range at 2.2 nm.</P></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja907984r'>ACS Electronic Supporting Info</A></P>