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John Pierce Wise - One of the best experts on this subject based on the ideXlab platform.
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abstract 3473 prolonged exposure to Zinc Chromate induces numerical chromosome instability via centrosome amplification in human lung cells
Cancer Research, 2010Co-Authors: Amie L Holmes, Stephen C Pelsue, Sandra S Wise, Jamie Gallagher, Wilma L Lingle, Jeffery L Salisbury, John Pierce WiseAbstract:Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Lung cancers are often characterized by numerical chromosome instability. Hexavalent chromium (Cr(VI)) is a well-known human lung carcinogen; however, its carcinogenic mechanism remains unknown. Studies show that solubility plays a key role in its carcinogenicity, with the particulate, or insoluble, compounds being the most potent carcinogens. Epidemiological and whole animal studies pinpoint particulate Zinc Chromate as the most potent Cr(VI) carcinogen; however, few studies have investigated its carcinogenic mechanism. Therefore, the goal of this study was to determine if Zinc Chromate induces numerical chromosome instability in human lung cells. We found that exposure to Zinc Chromate for 24 h did not induce aneuploidy but longer exposures induced both concentration- and time-dependent increases in aneuploid metaphases. For example, exposure to 0.1, 0.15 and 0.2 ug/cm2 Zinc Chromate for 120 h induced 28, 40 and 44 percent aneuploid metaphases, respectively, with increases in hypodiploid, hyperdiploid and tetraploid metaphases. Consistent with the aneuploidy data, a 24 h exposure to Zinc Chromate did not induce centrosome amplification but more chronic exposures induced concentration- and time-dependent increases in centrosome amplification in both interphase and mitotic cells. Exposure to 0.1, 0.15 and 0.2 ug/cm2 Zinc Chromate for 120 h induced centrosome amplification in 13.9, 18 and 21.3 percent of interphase cells and 21, 33 and 46 percent of mitotic cells. In order to determine the mechanism of centrosome amplification, we investigated the number of centrioles in each centrosome and found that cells with amplified centrosomes exhibited centrosomes with normal centriole pairs and centrosomes with centriolar defects indicating multiple mechanisms are involved in Zinc Chromate-induced centrosome amplification. Lastly, we found that chronic exposure to Zinc Chromate induced a prolonged G2 arrest. All together, these data indicate that chronic exposure to Zinc Chromate induces numerical chromosome instability via centrosome amplification in human lung cells. This work was supported by NIEHS grant ES016893 (J.P.W.), cooperative agreement #EP-08-01 through the Maine Space Grant Consortium (J.P.W.), EPA GRO Fellowship MA-91685401 (A.L.H.) and the Maine Center for Toxicology and Environmental Health at the University of Southern Maine. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3473.
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chronic exposure to Zinc Chromate induces centrosome amplification and spindle assembly checkpoint bypass in human lung fibroblasts
Chemical Research in Toxicology, 2010Co-Authors: Amie L Holmes, Stephen C Pelsue, Sandra S Wise, Abou Elmakarim Aboueissa, Wilma Lingle, Jeffery Salisbury, Jamie Gallagher, John Pierce WiseAbstract:Hexavalent chromium (Cr(VI)) compounds are known human lung carcinogens. Solubility plays an important role in its carcinogenicity with the particulate or insoluble form being the most potent. Of the particulate Cr(VI) compounds, Zinc Chromate appears to be the most potent carcinogen; however, very few studies have investigated its carcinogenic mechanism. In this study, we investigated the ability of chronic exposure to Zinc Chromate to induce numerical chromosome instability. We found no increase in aneuploidy after a 24 h exposure to Zinc Chromate, but with more chronic exposures, Zinc Chromate induced concentration- and time-dependent increases in aneuploidy in the form of hypodiploidy, hyperdiploidy, and tetraploidy. Zinc Chromate also induced centrosome amplification in a concentration- and time-dependent manner in both interphase and mitotic cells after chronic exposure, producing cells with centriolar defects. Furthermore, chronic exposure to Zinc Chromate induced concentration- and time-dependent ...
Amie L Holmes - One of the best experts on this subject based on the ideXlab platform.
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abstract 3473 prolonged exposure to Zinc Chromate induces numerical chromosome instability via centrosome amplification in human lung cells
Cancer Research, 2010Co-Authors: Amie L Holmes, Stephen C Pelsue, Sandra S Wise, Jamie Gallagher, Wilma L Lingle, Jeffery L Salisbury, John Pierce WiseAbstract:Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Lung cancers are often characterized by numerical chromosome instability. Hexavalent chromium (Cr(VI)) is a well-known human lung carcinogen; however, its carcinogenic mechanism remains unknown. Studies show that solubility plays a key role in its carcinogenicity, with the particulate, or insoluble, compounds being the most potent carcinogens. Epidemiological and whole animal studies pinpoint particulate Zinc Chromate as the most potent Cr(VI) carcinogen; however, few studies have investigated its carcinogenic mechanism. Therefore, the goal of this study was to determine if Zinc Chromate induces numerical chromosome instability in human lung cells. We found that exposure to Zinc Chromate for 24 h did not induce aneuploidy but longer exposures induced both concentration- and time-dependent increases in aneuploid metaphases. For example, exposure to 0.1, 0.15 and 0.2 ug/cm2 Zinc Chromate for 120 h induced 28, 40 and 44 percent aneuploid metaphases, respectively, with increases in hypodiploid, hyperdiploid and tetraploid metaphases. Consistent with the aneuploidy data, a 24 h exposure to Zinc Chromate did not induce centrosome amplification but more chronic exposures induced concentration- and time-dependent increases in centrosome amplification in both interphase and mitotic cells. Exposure to 0.1, 0.15 and 0.2 ug/cm2 Zinc Chromate for 120 h induced centrosome amplification in 13.9, 18 and 21.3 percent of interphase cells and 21, 33 and 46 percent of mitotic cells. In order to determine the mechanism of centrosome amplification, we investigated the number of centrioles in each centrosome and found that cells with amplified centrosomes exhibited centrosomes with normal centriole pairs and centrosomes with centriolar defects indicating multiple mechanisms are involved in Zinc Chromate-induced centrosome amplification. Lastly, we found that chronic exposure to Zinc Chromate induced a prolonged G2 arrest. All together, these data indicate that chronic exposure to Zinc Chromate induces numerical chromosome instability via centrosome amplification in human lung cells. This work was supported by NIEHS grant ES016893 (J.P.W.), cooperative agreement #EP-08-01 through the Maine Space Grant Consortium (J.P.W.), EPA GRO Fellowship MA-91685401 (A.L.H.) and the Maine Center for Toxicology and Environmental Health at the University of Southern Maine. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3473.
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chronic exposure to Zinc Chromate induces centrosome amplification and spindle assembly checkpoint bypass in human lung fibroblasts
Chemical Research in Toxicology, 2010Co-Authors: Amie L Holmes, Stephen C Pelsue, Sandra S Wise, Abou Elmakarim Aboueissa, Wilma Lingle, Jeffery Salisbury, Jamie Gallagher, John Pierce WiseAbstract:Hexavalent chromium (Cr(VI)) compounds are known human lung carcinogens. Solubility plays an important role in its carcinogenicity with the particulate or insoluble form being the most potent. Of the particulate Cr(VI) compounds, Zinc Chromate appears to be the most potent carcinogen; however, very few studies have investigated its carcinogenic mechanism. In this study, we investigated the ability of chronic exposure to Zinc Chromate to induce numerical chromosome instability. We found no increase in aneuploidy after a 24 h exposure to Zinc Chromate, but with more chronic exposures, Zinc Chromate induced concentration- and time-dependent increases in aneuploidy in the form of hypodiploidy, hyperdiploidy, and tetraploidy. Zinc Chromate also induced centrosome amplification in a concentration- and time-dependent manner in both interphase and mitotic cells after chronic exposure, producing cells with centriolar defects. Furthermore, chronic exposure to Zinc Chromate induced concentration- and time-dependent ...
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Zinc Chromate induces chromosome instability and dna double strand breaks in human lung cells
Toxicology and Applied Pharmacology, 2009Co-Authors: Hong Xie, Amie L Holmes, Jamie L Young, Qin Qin, Kellie Joyce, Stephen C Pelsue, Cheng Peng, Sandra S Wise, Antony S Jeevarajan, William T WallaceAbstract:Hexavalent chromium Cr(VI) is a respiratory toxicant and carcinogen, with solubility playing an important role in its carcinogenic potential. Zinc Chromate, a water insoluble or 'particulate' Cr(VI) compound, has been shown to be carcinogenic in epidemiology studies and to induce tumors in experimental animals, but its genotoxicity is poorly understood. Our study shows that Zinc Chromate induced concentration-dependent increases in cytotoxicity, chromosome damage and DNA double strand breaks in human lung cells. In response to Zinc Chromate-induced breaks, MRE11 expression was increased and ATM and ATR were phosphorylated, indicating that the DNA double strand break repair system was initiated in the cells. In addition, our data show that Zinc Chromate-induced double strand breaks were only observed in the G2/M phase population, with no significant amount of double strand breaks observed in G1 and S phase cells. These data will aid in understanding the mechanisms of Zinc Chromate toxicity and carcinogenesis.
Daniel De La Fuente - One of the best experts on this subject based on the ideXlab platform.
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Exploring the corrosion inhibition of aluminium by coatings formulated with calcium exchange bentonite
'Elsevier BV', 2018Co-Authors: Vega J. M., Granizo N., Simancas Peco Joaquín, Díaz Iván, Morcillo Manuel, Daniel De La FuenteAbstract:Enviromentally friendly calcium-exchange derived from naturally occurring sodium-bentonite clays (Wyoming) are shown to significantly enhance resistance to corrosion protection in organic coatings applied on aluminium under aggressive environment typical from industrial areas. Two pigments classified as ion-exchange were also studied for comparison (Shieldex and Al-Zn-vanadate hydrotalcite) together with Zinc Chromate as reference corrosion protection pigment. Electrochemical impedance spectroscopy (EIS) is used to study the corrosion protection in the metal/coating interface of pigmented alkyd coatings and a blank coating (without corrosion inhibitor pigment) in combination with visual inspection. The protection performance of these specimens was studied using outdoor exposure (two atmospheres with different aggressiveness) and accelerated tests (condensing humidity, salt spray and Kesternich tests, respectively). Results have shown strong dependence of the coating performance with the aggressive environment (e.g. Cl, H, SO) for all coatings formulated with ion-exchange pigments. The corrosion protection of the underlying aluminium substrate provided by calcium-exchange bentonite coating was shown under the presence of cationic aggressive agents in accelerated corrosion tests (specifically in Kesternich test). However, poor performance was observed for this coating using chlorides as an aggressive agent. Therefore, the presence of bentonite pigment improves the corrosion protection due to the cation-exchange mechanism.The authors gratefully acknowledge the financial support for this work from the Ministry of Science and Innovation of Spain (CICYT-MAT 2005-06261). Authors would like to thanks to J. Guzmán of Productos Diez for coating manufacture, Tolsa SA for supplying the anticorrosive pigment and the language revision by Mrs. Mª Begoña Vega Carpintero (BSc English Philology). J.M. Vega also acknowledges the PhD scholarship financed by CSIC-MICINN.Peer Reviewe
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Corrosion inhibition of aluminum by organic coatings formulated with calcium exchange silica pigment
'Springer Science and Business Media LLC', 2013Co-Authors: Vega J. M., Daniel De La Fuente, Granizo N., Simancas Peco Joaquín, Díaz Iván, Morcillo ManuelAbstract:One of the first commercial ion-exchange anticorrosive pigments to be developed was Shieldex (Si/Ca). Its proposed corrosion protection mechanism, based on the retention of aggressive cations and the subsequent release of calcium cations, has created certain controversy. A number of studies have focused on the anticorrosive behavior of this pigment on carbon steel and galvanized steel to replace Chromates (Cr6+) as inhibitor pigment, but none has considered its performance on aluminum or aluminum alloys. In this research, alkyd coatings have been formulated with Si/ Ca pigment at different concentrations and applied on aluminum 1050 (Al 99.5%) specimens. Corrosion performance has been also evaluated in the laboratory by electrochemical impedance spectroscopy. The study has also considered an organic coating with Zinc Chromate anticorrosive pigment for comparative purposes. The results obtained with organic coatings formulated with Si/Ca pigments con- firm that they provide corrosion protection of the underlying aluminum substrate, even improving the behavior of the reference Zinc Chromate in some environmental conditionsPeer Reviewe
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Anticorrosive behaviour of alkyd paints formulated with ion-exchange pigments
'Elsevier BV', 2013Co-Authors: Chico Belén, Daniel De La Fuente, Vega J. M., Granizo N., Simancas Peco Joaquín, Díaz Iván, Morcillo ManuelAbstract:Hexavalent chromium compounds (Chromates) have been widely used as inhibitive pigments in the formulation of anticorrosive paints. However, their high toxicity and carcinogenic effects are forcing the development of effective Chromate-free organic coatings. One such alternative, which is very attractive from a scientific point of view, is the use of ion-exchangeable pigments (IEPs). The few studies conducted with this type of pigment are not conclusive about their anticorrosive efficiency and controversy surrounds their functioning mechanisms, interchange capacity and anticorrosive performance. In the present research, which focuses on the anticorrosive protection of this type of pigment, alkyd paint coatings formulated with vanadate-hydrotalcite (HT/V) (anionic) and calcium/silica (Ca/Si) (cationic) IEPs have been applied on low carbon steel specimens. A traditional Zinc Chromate pigment has also been used for comparative purposes. The effect of these non-toxic pigments on the protective properties of coatings has been tested by means of natural and accelerated corrosion tests (humidity, salt spray and Kesternich, 0.2 l SO2) and electrochemical impedance spectroscopy (EIS). None of the IEPs equalled the anticorrosive behaviour of the Zinc Chromate in the different tests. The anionic pigment (HT/V) seems to present good behaviour in chloride environments (salt spray, NaCl solutions, etc.) while the cationic pigment (Ca/Si) performs well in the humidity condensation and SO2 tests. © 2007 Elsevier B.V. All rights reserved.Peer Reviewe
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Paint systems formulated with ion-exchange pigments applied on carbon steel: Effect of surface preparation
'Elsevier BV', 2013Co-Authors: Granizo N., Daniel De La Fuente, Vega J. M., Díaz Iván, Chico Belén, Morcillo ManuelAbstract:Ion exchange pigments are a scientifically very interesting alternative to Chromates that have not yet been fully explored. This study considers the following candidate anticorrosive pigments: calcium-exchanged silica (Si/Ca), hydrotalcite/vanadate (HT/V) and calcium bentonite (Bentonite/Ca). Paint systems manufactured with these ion exchange pigments have been subjected to adhesion, permeability and accelerated corrosion laboratory tests (humidity condensation (HC) and salt fog (SF)), simulating environments of low and high corrosivity, in order to assess their anticorrosive behaviour in comparison with a Zinc Chromate reference system. For this purpose the degree of coating degradation has been monitored: blistering, underfilm corrosion and delamination from scribe. This paper focuses on the effect of several parameters of interest when designing a paint system: (a) sanding treatment of the base steel prior to application of the primer paint; (b) pigment concentration in the primer paint coating; and (c) application of a topcoat layer over the primer coating. © 2010 Elsevier B.V. All rights reserved.Peer Reviewe
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Ion-exchange pigments in primer paints for anticorrosive protection of steel in atmospheric service: Cation-exchange pigments
'Elsevier BV', 2013Co-Authors: Granizo N., Daniel De La Fuente, Vega J. M., Simancas Peco Joaquín, Morcillo ManuelAbstract:Hexavalent chromium compounds (Chromates) have been widely used as inhibitor pigments in the formulation of anticorrosive primers. However, their high toxicity and carcinogenic effects are forcing the development of effective Chromate-free organic coatings. One such alternative is the use of ion-exchangeable pigments. Studies of these pigments have not been conclusive about their anticorrosive efficiency and controversy surrounds their functional mechanisms, exchange capacity and anticorrosive performance. This paper focuses on the anticorrosive protection afforded by cation-exchange pigments. Alkyd primer coatings formulated with non-toxic silica/calcium (Si/Ca) and bentonite/calcium (BT/Ca) pigments have been applied on carbon steel specimens, and the effect of these pigments on the protective properties of the coatings has been evaluated by means of natural and accelerated corrosion tests (humidity, salt spray and Kesternich, 0.2 L SO 2). A traditional Zinc Chromate (ZC) pigment has also been used for comparative purposes. The cation-exchange capacity and inhibitor capacity of the Si/Ca and BT/Ca pigments has been evaluated, and the inhibiting power of both is seen to be less than that of the traditional ZC pigment. The formation of a calcium silicate film with good protective characteristics on the underlying steel is corroborated in the case of the Si/Ca pigment, whereas the anticorrosive properties of the BT/Ca pigment are deficient in the different tested environments. © 2012 Elsevier B.V.Peer Reviewe
Morcillo Manuel - One of the best experts on this subject based on the ideXlab platform.
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Exploring the corrosion inhibition of aluminium by coatings formulated with calcium exchange bentonite
'Elsevier BV', 2018Co-Authors: Vega J. M., Granizo N., Simancas Peco Joaquín, Díaz Iván, Morcillo Manuel, Daniel De La FuenteAbstract:Enviromentally friendly calcium-exchange derived from naturally occurring sodium-bentonite clays (Wyoming) are shown to significantly enhance resistance to corrosion protection in organic coatings applied on aluminium under aggressive environment typical from industrial areas. Two pigments classified as ion-exchange were also studied for comparison (Shieldex and Al-Zn-vanadate hydrotalcite) together with Zinc Chromate as reference corrosion protection pigment. Electrochemical impedance spectroscopy (EIS) is used to study the corrosion protection in the metal/coating interface of pigmented alkyd coatings and a blank coating (without corrosion inhibitor pigment) in combination with visual inspection. The protection performance of these specimens was studied using outdoor exposure (two atmospheres with different aggressiveness) and accelerated tests (condensing humidity, salt spray and Kesternich tests, respectively). Results have shown strong dependence of the coating performance with the aggressive environment (e.g. Cl, H, SO) for all coatings formulated with ion-exchange pigments. The corrosion protection of the underlying aluminium substrate provided by calcium-exchange bentonite coating was shown under the presence of cationic aggressive agents in accelerated corrosion tests (specifically in Kesternich test). However, poor performance was observed for this coating using chlorides as an aggressive agent. Therefore, the presence of bentonite pigment improves the corrosion protection due to the cation-exchange mechanism.The authors gratefully acknowledge the financial support for this work from the Ministry of Science and Innovation of Spain (CICYT-MAT 2005-06261). Authors would like to thanks to J. Guzmán of Productos Diez for coating manufacture, Tolsa SA for supplying the anticorrosive pigment and the language revision by Mrs. Mª Begoña Vega Carpintero (BSc English Philology). J.M. Vega also acknowledges the PhD scholarship financed by CSIC-MICINN.Peer Reviewe
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Corrosion inhibition of aluminum by organic coatings formulated with calcium exchange silica pigment
'Springer Science and Business Media LLC', 2013Co-Authors: Vega J. M., Daniel De La Fuente, Granizo N., Simancas Peco Joaquín, Díaz Iván, Morcillo ManuelAbstract:One of the first commercial ion-exchange anticorrosive pigments to be developed was Shieldex (Si/Ca). Its proposed corrosion protection mechanism, based on the retention of aggressive cations and the subsequent release of calcium cations, has created certain controversy. A number of studies have focused on the anticorrosive behavior of this pigment on carbon steel and galvanized steel to replace Chromates (Cr6+) as inhibitor pigment, but none has considered its performance on aluminum or aluminum alloys. In this research, alkyd coatings have been formulated with Si/ Ca pigment at different concentrations and applied on aluminum 1050 (Al 99.5%) specimens. Corrosion performance has been also evaluated in the laboratory by electrochemical impedance spectroscopy. The study has also considered an organic coating with Zinc Chromate anticorrosive pigment for comparative purposes. The results obtained with organic coatings formulated with Si/Ca pigments con- firm that they provide corrosion protection of the underlying aluminum substrate, even improving the behavior of the reference Zinc Chromate in some environmental conditionsPeer Reviewe
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Anticorrosive behaviour of alkyd paints formulated with ion-exchange pigments
'Elsevier BV', 2013Co-Authors: Chico Belén, Daniel De La Fuente, Vega J. M., Granizo N., Simancas Peco Joaquín, Díaz Iván, Morcillo ManuelAbstract:Hexavalent chromium compounds (Chromates) have been widely used as inhibitive pigments in the formulation of anticorrosive paints. However, their high toxicity and carcinogenic effects are forcing the development of effective Chromate-free organic coatings. One such alternative, which is very attractive from a scientific point of view, is the use of ion-exchangeable pigments (IEPs). The few studies conducted with this type of pigment are not conclusive about their anticorrosive efficiency and controversy surrounds their functioning mechanisms, interchange capacity and anticorrosive performance. In the present research, which focuses on the anticorrosive protection of this type of pigment, alkyd paint coatings formulated with vanadate-hydrotalcite (HT/V) (anionic) and calcium/silica (Ca/Si) (cationic) IEPs have been applied on low carbon steel specimens. A traditional Zinc Chromate pigment has also been used for comparative purposes. The effect of these non-toxic pigments on the protective properties of coatings has been tested by means of natural and accelerated corrosion tests (humidity, salt spray and Kesternich, 0.2 l SO2) and electrochemical impedance spectroscopy (EIS). None of the IEPs equalled the anticorrosive behaviour of the Zinc Chromate in the different tests. The anionic pigment (HT/V) seems to present good behaviour in chloride environments (salt spray, NaCl solutions, etc.) while the cationic pigment (Ca/Si) performs well in the humidity condensation and SO2 tests. © 2007 Elsevier B.V. All rights reserved.Peer Reviewe
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Paint systems formulated with ion-exchange pigments applied on carbon steel: Effect of surface preparation
'Elsevier BV', 2013Co-Authors: Granizo N., Daniel De La Fuente, Vega J. M., Díaz Iván, Chico Belén, Morcillo ManuelAbstract:Ion exchange pigments are a scientifically very interesting alternative to Chromates that have not yet been fully explored. This study considers the following candidate anticorrosive pigments: calcium-exchanged silica (Si/Ca), hydrotalcite/vanadate (HT/V) and calcium bentonite (Bentonite/Ca). Paint systems manufactured with these ion exchange pigments have been subjected to adhesion, permeability and accelerated corrosion laboratory tests (humidity condensation (HC) and salt fog (SF)), simulating environments of low and high corrosivity, in order to assess their anticorrosive behaviour in comparison with a Zinc Chromate reference system. For this purpose the degree of coating degradation has been monitored: blistering, underfilm corrosion and delamination from scribe. This paper focuses on the effect of several parameters of interest when designing a paint system: (a) sanding treatment of the base steel prior to application of the primer paint; (b) pigment concentration in the primer paint coating; and (c) application of a topcoat layer over the primer coating. © 2010 Elsevier B.V. All rights reserved.Peer Reviewe
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Ion-exchange pigments in primer paints for anticorrosive protection of steel in atmospheric service: Cation-exchange pigments
'Elsevier BV', 2013Co-Authors: Granizo N., Daniel De La Fuente, Vega J. M., Simancas Peco Joaquín, Morcillo ManuelAbstract:Hexavalent chromium compounds (Chromates) have been widely used as inhibitor pigments in the formulation of anticorrosive primers. However, their high toxicity and carcinogenic effects are forcing the development of effective Chromate-free organic coatings. One such alternative is the use of ion-exchangeable pigments. Studies of these pigments have not been conclusive about their anticorrosive efficiency and controversy surrounds their functional mechanisms, exchange capacity and anticorrosive performance. This paper focuses on the anticorrosive protection afforded by cation-exchange pigments. Alkyd primer coatings formulated with non-toxic silica/calcium (Si/Ca) and bentonite/calcium (BT/Ca) pigments have been applied on carbon steel specimens, and the effect of these pigments on the protective properties of the coatings has been evaluated by means of natural and accelerated corrosion tests (humidity, salt spray and Kesternich, 0.2 L SO 2). A traditional Zinc Chromate (ZC) pigment has also been used for comparative purposes. The cation-exchange capacity and inhibitor capacity of the Si/Ca and BT/Ca pigments has been evaluated, and the inhibiting power of both is seen to be less than that of the traditional ZC pigment. The formation of a calcium silicate film with good protective characteristics on the underlying steel is corroborated in the case of the Si/Ca pigment, whereas the anticorrosive properties of the BT/Ca pigment are deficient in the different tested environments. © 2012 Elsevier B.V.Peer Reviewe
Stephen C Pelsue - One of the best experts on this subject based on the ideXlab platform.
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abstract 3473 prolonged exposure to Zinc Chromate induces numerical chromosome instability via centrosome amplification in human lung cells
Cancer Research, 2010Co-Authors: Amie L Holmes, Stephen C Pelsue, Sandra S Wise, Jamie Gallagher, Wilma L Lingle, Jeffery L Salisbury, John Pierce WiseAbstract:Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Lung cancers are often characterized by numerical chromosome instability. Hexavalent chromium (Cr(VI)) is a well-known human lung carcinogen; however, its carcinogenic mechanism remains unknown. Studies show that solubility plays a key role in its carcinogenicity, with the particulate, or insoluble, compounds being the most potent carcinogens. Epidemiological and whole animal studies pinpoint particulate Zinc Chromate as the most potent Cr(VI) carcinogen; however, few studies have investigated its carcinogenic mechanism. Therefore, the goal of this study was to determine if Zinc Chromate induces numerical chromosome instability in human lung cells. We found that exposure to Zinc Chromate for 24 h did not induce aneuploidy but longer exposures induced both concentration- and time-dependent increases in aneuploid metaphases. For example, exposure to 0.1, 0.15 and 0.2 ug/cm2 Zinc Chromate for 120 h induced 28, 40 and 44 percent aneuploid metaphases, respectively, with increases in hypodiploid, hyperdiploid and tetraploid metaphases. Consistent with the aneuploidy data, a 24 h exposure to Zinc Chromate did not induce centrosome amplification but more chronic exposures induced concentration- and time-dependent increases in centrosome amplification in both interphase and mitotic cells. Exposure to 0.1, 0.15 and 0.2 ug/cm2 Zinc Chromate for 120 h induced centrosome amplification in 13.9, 18 and 21.3 percent of interphase cells and 21, 33 and 46 percent of mitotic cells. In order to determine the mechanism of centrosome amplification, we investigated the number of centrioles in each centrosome and found that cells with amplified centrosomes exhibited centrosomes with normal centriole pairs and centrosomes with centriolar defects indicating multiple mechanisms are involved in Zinc Chromate-induced centrosome amplification. Lastly, we found that chronic exposure to Zinc Chromate induced a prolonged G2 arrest. All together, these data indicate that chronic exposure to Zinc Chromate induces numerical chromosome instability via centrosome amplification in human lung cells. This work was supported by NIEHS grant ES016893 (J.P.W.), cooperative agreement #EP-08-01 through the Maine Space Grant Consortium (J.P.W.), EPA GRO Fellowship MA-91685401 (A.L.H.) and the Maine Center for Toxicology and Environmental Health at the University of Southern Maine. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3473.
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chronic exposure to Zinc Chromate induces centrosome amplification and spindle assembly checkpoint bypass in human lung fibroblasts
Chemical Research in Toxicology, 2010Co-Authors: Amie L Holmes, Stephen C Pelsue, Sandra S Wise, Abou Elmakarim Aboueissa, Wilma Lingle, Jeffery Salisbury, Jamie Gallagher, John Pierce WiseAbstract:Hexavalent chromium (Cr(VI)) compounds are known human lung carcinogens. Solubility plays an important role in its carcinogenicity with the particulate or insoluble form being the most potent. Of the particulate Cr(VI) compounds, Zinc Chromate appears to be the most potent carcinogen; however, very few studies have investigated its carcinogenic mechanism. In this study, we investigated the ability of chronic exposure to Zinc Chromate to induce numerical chromosome instability. We found no increase in aneuploidy after a 24 h exposure to Zinc Chromate, but with more chronic exposures, Zinc Chromate induced concentration- and time-dependent increases in aneuploidy in the form of hypodiploidy, hyperdiploidy, and tetraploidy. Zinc Chromate also induced centrosome amplification in a concentration- and time-dependent manner in both interphase and mitotic cells after chronic exposure, producing cells with centriolar defects. Furthermore, chronic exposure to Zinc Chromate induced concentration- and time-dependent ...
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Zinc Chromate induces chromosome instability and dna double strand breaks in human lung cells
Toxicology and Applied Pharmacology, 2009Co-Authors: Hong Xie, Amie L Holmes, Jamie L Young, Qin Qin, Kellie Joyce, Stephen C Pelsue, Cheng Peng, Sandra S Wise, Antony S Jeevarajan, William T WallaceAbstract:Hexavalent chromium Cr(VI) is a respiratory toxicant and carcinogen, with solubility playing an important role in its carcinogenic potential. Zinc Chromate, a water insoluble or 'particulate' Cr(VI) compound, has been shown to be carcinogenic in epidemiology studies and to induce tumors in experimental animals, but its genotoxicity is poorly understood. Our study shows that Zinc Chromate induced concentration-dependent increases in cytotoxicity, chromosome damage and DNA double strand breaks in human lung cells. In response to Zinc Chromate-induced breaks, MRE11 expression was increased and ATM and ATR were phosphorylated, indicating that the DNA double strand break repair system was initiated in the cells. In addition, our data show that Zinc Chromate-induced double strand breaks were only observed in the G2/M phase population, with no significant amount of double strand breaks observed in G1 and S phase cells. These data will aid in understanding the mechanisms of Zinc Chromate toxicity and carcinogenesis.
