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Sorvina A, Bader CA, Darby JRT, Lock MC, Soo JY, Johnson IRD, Caporale C, Voelcker NH, Stagni S, Massi M, Morrison JL, Plush SE, Brooks DA. Mitochondrial imaging in live or fixed tissues using a luminescent iridium complex. Sci Rep 2018; 8:8191. [PMID: 29844412 PMCID: PMC5974328 DOI: 10.1038/s41598-018-24672-w] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 03/14/2018] [Indexed: 02/06/2023] Open
Abstract
Mitochondrial morphology is important for the function of this critical organelle and, accordingly, altered mitochondrial structure is exhibited in many pathologies. Imaging of mitochondria can therefore provide important information about disease presence and progression. However, mitochondrial imaging is currently limited by the availability of agents that have the capacity to image mitochondrial morphology in both live and fixed samples. This can be particularly problematic in clinical studies or large, multi-centre cohort studies, where tissue archiving by fixation is often more practical. We previously reported the synthesis of an iridium coordination complex [Ir(ppy)2(MeTzPyPhCN)]+; where ppy is a cyclometalated 2-phenylpyridine and TzPyPhCN is the 5-(5-(4-cyanophen-1-yl)pyrid-2-yl)tetrazolate ligand; and showed that this complex (herein referred to as IraZolve-Mito) has a high specificity for mitochondria in live cells. Here we demonstrate that IraZolve-Mito can also effectively stain mitochondria in both live and fixed tissue samples. The staining protocol proposed is versatile, providing a universal procedure for cell biologists and pathologists to visualise mitochondria.
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Affiliation(s)
- Alexandra Sorvina
- Mechanisms in Cell Biology and Disease Research Group, School of Pharmacy and Medical Sciences, Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, 5001, Australia
| | - Christie A Bader
- Mechanisms in Cell Biology and Disease Research Group, School of Pharmacy and Medical Sciences, Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, 5001, Australia
| | - Jack R T Darby
- Early Origins of Adult Health Research Group, School of Pharmacy and Medical Sciences, Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, 5001, Australia
| | - Mitchell C Lock
- Early Origins of Adult Health Research Group, School of Pharmacy and Medical Sciences, Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, 5001, Australia
| | - Jia Yin Soo
- Early Origins of Adult Health Research Group, School of Pharmacy and Medical Sciences, Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, 5001, Australia
| | - Ian R D Johnson
- Mechanisms in Cell Biology and Disease Research Group, School of Pharmacy and Medical Sciences, Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, 5001, Australia
| | - Chiara Caporale
- Department of Chemistry and Curtin Institute for Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia, 6102, Australia
| | - Nicolas H Voelcker
- Future Industries Institute, University of South Australia, Adelaide, South Australia, 5095, Australia
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia
| | - Stefano Stagni
- Department of Industrial Chemistry "Toso Montanari", University of Bologna, Bologna, I-40136, Italy
| | - Massimiliano Massi
- Mechanisms in Cell Biology and Disease Research Group, School of Pharmacy and Medical Sciences, Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, 5001, Australia
- Department of Chemistry and Curtin Institute for Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia, 6102, Australia
| | - Janna L Morrison
- Early Origins of Adult Health Research Group, School of Pharmacy and Medical Sciences, Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, 5001, Australia
| | - Sally E Plush
- Mechanisms in Cell Biology and Disease Research Group, School of Pharmacy and Medical Sciences, Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, 5001, Australia.
- Future Industries Institute, University of South Australia, Adelaide, South Australia, 5095, Australia.
| | - Douglas A Brooks
- Mechanisms in Cell Biology and Disease Research Group, School of Pharmacy and Medical Sciences, Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, 5001, Australia.
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Ozkantar N, Yilmaz E, Soylak M, Tuzen M. Solid-phase extraction of iridium from soil and water samples by using activated carbon cloth prior to its spectrophotometric determination. Environ Monit Assess 2015; 187:501. [PMID: 26160741 DOI: 10.1007/s10661-015-4720-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Accepted: 06/29/2015] [Indexed: 06/04/2023]
Abstract
A solid-phase extraction method for separation and preconcentration of Ir(IV) ion by using activated carbon cloth (ACC) has been presented. Ir(IV) as their 1-(2-pyridylazo) 2-naphtol (PAN) chelate was adsorbed on ACC at pH 2.0 and was eluted from ACC with acidic dimethylformamide (DMF). The Ir(IV) concentration was determined at 536 nm as Ir(IV)-PAN complex by using UV-vis spectrophotometer. The analytical parameters including pH, sample and eluent flow rates, amount of PAN, eluent type, concentration, and sample volume were optimized. The effects of foreign ions on the recoveries of iridium were also investigated. The preconcentration factor was calculated as 60. The limit of detection (LOD) and the limit of quantification (LOQ) of the method were found as 0.039 and 0.129 μg L(-1), respectively. The method was applied to soil and water samples for iridium determination.
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Affiliation(s)
- Nebiye Ozkantar
- Chemistry Department, Faculty of Science and Arts, Gaziosmanpasa University, 60250, Tokat, Turkey
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Eakins JS, Kouroukla E. Luminescence-based retrospective dosimetry using Al2O3 from mobile phones: a simulation approach to determine the effects of position. J Radiol Prot 2015; 35:343-381. [PMID: 25884152 DOI: 10.1088/0952-4746/35/2/343] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Monte Carlo modelling has been performed in support of efforts to establish emergency dosimetry services based on optically or thermally stimulated luminescence (OSL/TL) of the Al(2)O(3) substrate present on the resistors found in mobile phones, which can act as fortuitous retrospective dosemeters for photon exposures. Specifically, a range of exposure conditions has been modelled to assess the dependence of the dosimetry on factors such as the position of resistors within a phone, the orientation of the phone relative to the source, and the location of the phone relative to its owner. Variations due to the resistors' positions and the phone's orientation were generally found to contribute just a few percent to the uncertainty on the dose assessments, though the electrical contacts surrounding the resistors could potentially enhance these by several 10s of percent. But, the location of the phone was found to impact dosimetry greatly. The largest discrepancies in the results were found for low-energy exposures: for (192)Ir, differences of up to an order-of-magnitude were found between resistor and whole body doses. The outcome of the work was to derive correction / calibration factors that can be applied to estimate whole body doses from OSL/TL readings, the accurate application of which would depend on the knowledge of the exposure geometry and the degree of conservatism acceptable for the dose assessment.
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Affiliation(s)
- J S Eakins
- Public Health England CRCE, Chilton, Didcot, OXON, UK
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Sager M, Chon HT, Marton L. Spatial variation of contaminant elements of roadside dust samples from Budapest (Hungary) and Seoul (Republic of Korea), including Pt, Pd and Ir. Environ Geochem Health 2015; 37:181-193. [PMID: 25108588 DOI: 10.1007/s10653-014-9639-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2013] [Accepted: 07/23/2014] [Indexed: 06/03/2023]
Abstract
Roadside dusts were studied to explain the spatial variation and present levels of contaminant elements including Pt, Pd and Ir in urban environment and around Budapest (Hungary) and Seoul (Republic of Korea). The samples were collected from six sites of high traffic volumes in Seoul metropolitan city and from two control sites within the suburbs of Seoul, for comparison. Similarly, road dust samples were obtained two times from traffic focal points in Budapest, from the large bridges across the River Danube, from Margitsziget (an island in the Danube in the northern part of Budapest, used for recreation) as well as from main roads (no highways) outside Budapest. The samples were analysed for contaminant elements by ICP-AES and for Pt, Pd and Ir by ICP-MS. The highest Pt, Pd and Ir levels in road dusts were found from major roads with high traffic volume, but correlations with other contaminant elements were low, however. This reflects automobile catalytic converter to be an important source. To interpret the obtained multi-element results in short, pollution index, contamination index and geo-accumulation index were calculated. Finally, the obtained data were compared with total concentrations encountered in dust samples from Madrid, Oslo, Tokyo and Muscat (Oman). Dust samples from Seoul reached top level concentrations for Cd-Zn-As-Co-Cr-Cu-Mo-Ni-Sn. Just Pb was rather low because unleaded gasoline was introduced as compulsory in 1993. Concentrations in Budapest dust samples were lower than from Seoul, except for Pb and Mg. Compared with Madrid as another continental site, Budapest was higher in Co-V-Zn. Dust from Oslo, which is not so large, contained more Mn-Na-Sr than dust from other towns, but less other metals.
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Affiliation(s)
- Manfred Sager
- Austrian Agency for Health and Food Safety, Spargelfeldstrasse 191, 1220, Vienna, Austria
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Baggaley E, Cao DK, Sykes D, Botchway SW, Weinstein JA, Ward MD. Combined two-photon excitation and d→f energy transfer in a water-soluble Ir(III)/Eu(III) dyad: two luminescence components from one molecule for cellular imaging. Chemistry 2014; 20:8898-903. [PMID: 24930403 PMCID: PMC4145666 DOI: 10.1002/chem.201403618] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Indexed: 11/18/2022]
Abstract
The first example of cell imaging using two independent emission components from a dinuclear d/f complex is reported. A water-stable, cell-permeable Ir(III) /Eu(III) dyad undergoes partial Ir→Eu energy transfer following two-photon excitation of the Ir unit at 780 nm. Excitation in the near-IR region generated simultaneously green Ir-based emission and red Eu-based emission from the same probe. The orders-of-magnitude difference in their timescales (Ir ca. μs; Eu ca. 0.5 ms) allowed them to be identified by time-gated detection. Phosphorescence lifetime imaging microscopy (PLIM) allowed the lifetime of the Ir-based emission to be measured in different parts of the cell. At the same time, the cells are simultaneously imaged by using the Eu-based emission component at longer timescales. This new approach to cellular imaging by using dual d/f emitters should therefore enable autofluorescence-free sensing of two different analytes, independently, simultaneously and in the same regions of a cell.
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Affiliation(s)
| | - Deng-Ke Cao
- Department of Chemistry, University of SheffieldSheffield S3 7HF (UK)
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing UniversityNanjing 210093 (P.R. China)
| | - Daniel Sykes
- Department of Chemistry, University of SheffieldSheffield S3 7HF (UK)
| | - Stanley W Botchway
- Rutherford Appleton Laboratory, STFC, Research Complex at Harwell, Harwell Science and Innovation CampusDidcot OX11 0FA (UK)
| | - Julia A Weinstein
- Department of Chemistry, University of SheffieldSheffield S3 7HF (UK)
| | - Michael D Ward
- Department of Chemistry, University of SheffieldSheffield S3 7HF (UK)
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Abstract
For many years now automotive exhaust catalysts have been used to reduce the significant amounts of harmful chemical substances generated by car engines, such as carbon monoxide, nitrogen oxides, and aromatic hydrocarbons. Although they considerably decrease environmental contamination with the above-mentioned compounds, it is known that catalysts contribute to the environmental load of platinum metals (essential components of catalysts), which are released with exhaust fumes. Contamination with platinum metals stems mainly from automotive exhaust converters, but other major sources also exist. Since platinum group elements (PGEs): platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru) and iridium (Ir) seem to spread in the environment and accumulate in living organisms, they may pose a threat to animals and humans. This paper discusses the modes and forms of PGE emission as well as their impact on the environment and living organisms.
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Affiliation(s)
- Justyna Pawlak
- Faculty of Biotechnology and Food Sciences, Lodz University of Technology, ul. Stefanowskiego 4/10, 90-924 Łódź, Poland.
| | - Elżbieta Łodyga-Chruścińska
- Faculty of Biotechnology and Food Sciences, Lodz University of Technology, ul. Stefanowskiego 4/10, 90-924 Łódź, Poland
| | - Jakub Chrustowicz
- Faculty of Biotechnology and Food Sciences, Lodz University of Technology, ul. Stefanowskiego 4/10, 90-924 Łódź, Poland
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Ma DL, Zhong HJ, Fu WC, Chan DSH, Kwan HY, Fong WF, Chung LH, Wong CY, Leung CH. Phosphorescent imaging of living cells using a cyclometalated iridium (III) complex. PLoS One 2013; 8:e55751. [PMID: 23457478 PMCID: PMC3573050 DOI: 10.1371/journal.pone.0055751] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 12/29/2012] [Indexed: 01/04/2023] Open
Abstract
A cell permeable cyclometalated iridium(III) complex has been developed as a phosphorescent probe for cell imaging. The iridium(III) solvato complex [Ir(phq)2(H2O]2)] preferentially stains the cytoplasm of both live and dead cells with a bright luminescence.
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Affiliation(s)
- Dik-Lung Ma
- Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.
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Soyol-Erdene TO, Huh Y, Hong S, Hur SD. A 50-year record of platinum, iridium, and rhodium in Antarctic snow: volcanic and anthropogenic sources. Environ Sci Technol 2011; 45:5929-5935. [PMID: 21662990 DOI: 10.1021/es2005732] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Antarctic snow preserves an atmospheric archive that enables the study of global atmospheric changes and anthropogenic disturbances from the past. We report atmospheric deposition rates of platinum group elements (PGEs) in Antarctica during the last ∼ 50 years based on determinations of Pt, Ir, and Rh in snow samples collected from Queen Maud Land, East Antarctica to evaluate changes in the global atmospheric budget of these noble metals. The 50-year average PGE concentrations in Antarctic snow were 17 fg g(-1) (4.7-76 fg g(-1)) for Pt, 0.12 fg g(-1) (<0.05-0.34 fg g(-1)) for Ir, and 0.71 fg g(-1) (0.12-8.8 fg g(-1)) for Rh. The concentration peaks for Pt, Ir, and Rh were observed at depths corresponding to volcanic eruption periods, indicating that PGEs can be used as a good tracer of volcanic activity in the past. A significant increase in concentrations and crustal enrichment factors for Pt and a slight enhancement in enrichment factors for Rh were observed after the 1980s. This suggests that there has been large-scale atmospheric pollution for Pt and probably for Rh since the 1980s, which may be attributed to the increasing emissions of these metals from anthropogenic sources such as automobile catalysts and metal production processes.
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Affiliation(s)
- Tseren-Ochir Soyol-Erdene
- School of Earth and Environmental Sciences, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-747, Korea
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Jakobi J, Menéndez-Manjón A, Chakravadhanula VSK, Kienle L, Wagener P, Barcikowski S. Stoichiometry of alloy nanoparticles from laser ablation of PtIr in acetone and their electrophoretic deposition on PtIr electrodes. Nanotechnology 2011; 22:145601. [PMID: 21346297 DOI: 10.1088/0957-4484/22/14/145601] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Charged Pt-Ir alloy nanoparticles are generated through femtosecond laser ablation of a Pt₉Ir target in acetone without using chemical precursors or stabilizing agents. Preservation of the target's stoichiometry in the colloidal nanoparticles is confirmed by transmission electron microscopy (TEM)-energy-dispersive x-ray spectroscopy (EDX), high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM)-EDX elemental maps, high resolution TEM and selected area electron diffraction (SAED) measurements. Results are discussed with reference to thermophysical properties and the phase diagram. The nanoparticles show a lognormal size distribution with a mean Feret particle size of 26 nm. The zeta potential of -45 mV indicates high stability of the colloid with a hydrodynamic diameter of 63 nm. The charge of the particles enables electrophoretic deposition of nanoparticles, creating nanoscale roughness on three-dimensional PtIr neural electrodes within a minute. In contrast to coating with Pt or Ir oxides, this method allows modification of the surface roughness without changing the chemical composition of PtIr.
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Affiliation(s)
- Jurij Jakobi
- Materials and Processes Department, Laser Zentrum Hannover, Hollerithallee 8, 30419 Hannover, Germany
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Kim JH, Kim CS, Whang JH. Assessment of radiation dose for surrounding organs and persons approaching implanted patients upon brachytherapy of prostate cancer with Iridium-192. Radiat Prot Dosimetry 2010; 141:283-288. [PMID: 20643801 DOI: 10.1093/rpd/ncq181] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
To assess a proper dose for radiation therapy fitting the typical physical characteristics of male Korean bodies, a mathematical phantom was prepared based on standard Korean male measurements. Upon brachytherapy of prostate cancer by implanting 192Ir into the prostate gland (the source organ), the absorbed dose of the prostate gland and surrounding organs and the expected dose of people within the vicinity were assessed. 192Ir, which has been the radionuclide of choice for prostate cancer brachytherapy, was selected for the simulation. It was assumed that 1 Ci of initial radioactivity would be administered. As a result, 1.28E-02 Gy/Ci was exhibited in the prostate gland of the source organ, and the dose to which persons within the vicinity were exposed was exhibited to be 9.19E-06 Sv at a distance of 30 cm from the front.
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Affiliation(s)
- J H Kim
- Department of Radiological Science, College of Health sciences, Catholic University of Pusan, Bugok 3-Dong, Geumjeong-gu, Busan 607-757, Republic of Korea.
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Jackson MT, Prichard HM, Sampson J. Platinum-group elements in sewage sludge and incinerator ash in the United Kingdom: assessment of PGE sources and mobility in cities. Sci Total Environ 2010; 408:1276-1285. [PMID: 19878972 DOI: 10.1016/j.scitotenv.2009.09.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 08/04/2009] [Accepted: 09/14/2009] [Indexed: 05/28/2023]
Abstract
Platinum-group element (PGE) concentrations in sewage sludge and incinerator ash compared with average PGE concentrations in road dust show a common pattern, characterized by a negative Rh anomaly. This similarity, found at 9 UK incinerators, suggests that there is a universal characteristic PGE pattern produced by common processes of dispersal of Pt, Pd and Rh derived from automobile catalytic converters. Ninety-one sewage sludge and incinerator ash samples from the sewage treatment facilities in Sheffield, Birmingham and 7 other UK cities were analyzed for PGE. The highest concentrations are 602ppb Pt and 710ppb Pd with lower maximum concentrations of 65ppb Rh, 100ppb Ru, 33ppb Ir and 12ppb Os. Ash from incinerated sewage was found to have higher PGE concentrations compared to the original sludge and the PGE ratios are preserved during incineration. Rh is more mobilized and dispersed than the other PGE as it is transported from roads into the drainage system and into sewage. Pt/Pd ratios of 1.0 in road dust and 0.9 in sewage and incinerator ash suggest that Pd is more mobile than Pt during dispersal. PGE abundances in stored incinerator ash of varying ages appear to have been affected by the variation in use of Pt, Pd and Rh in catalytic converters due to variation in their market prices. Concentrations of Os, Ir and Ru in ashes are greater in Sheffield and London than all the other city sites and may be derived from point industrial sources.
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Affiliation(s)
- M T Jackson
- School of Earth and Ocean Sciences, Cardiff University, Main Building, Cardiff, United Kingdom.
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Strnad L, Mihaljevic M, Ettler V, Barsová L, Zuna M, Sebek O. Distribution of the platinum group elements in peat deposit near a historic lead and silver mining district. Bull Environ Contam Toxicol 2008; 81:159-163. [PMID: 18373043 DOI: 10.1007/s00128-008-9407-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2007] [Accepted: 03/17/2008] [Indexed: 05/26/2023]
Abstract
Concentrations of platinum group elements (PGE) and Ag were studied in a minerotrophic peat deposit near a historic Pb-Ag mining district (Príbram, Czech Republic). The PGE determinations were performed by quadrupole ICP-MS after NiS fire assay procedure. In the individual peat layers (dated by measurement of (210)Pb activity) the PGE concentrations were low and ranged from 0.015 ng g(-1) (Ir) to 11.8 ng g(-1) (Pt). The enrichment of PGE (especially Pt) compared to the Earth crust contents were observed during two periods. The peak in the second half of 19th century was explained by massive increase of ore mining and affinity of PGE to concentrate in molten lead during Pb processing. The recent PGE enrichment in peat layers might be explained by automobile (with catalytic converters) exhaust fumes or processing of computer electronic parts by the smelter.
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Affiliation(s)
- Ladislav Strnad
- Laboratories of the Geological Institutes, Faculty of Science, Charles University, 128 43, Prague 2, Czech Republic.
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Iavicoli I, Carelli G, Bocca B, Caimi S, Fontana L, Alimonti A. Environmental and biological monitoring of iridium in the city of Rome. Chemosphere 2008; 71:568-573. [PMID: 17980403 DOI: 10.1016/j.chemosphere.2007.09.037] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Revised: 09/19/2007] [Accepted: 09/21/2007] [Indexed: 05/25/2023]
Abstract
The use of iridium in the latest catalytic converters to further reduce nitrogen oxide emission in the exhaust of lean-burn engines could result in increased atmospheric levels of this element in high-density vehicle traffic areas. The objective of this study is to assess environmental Ir pollution and its urinary levels in workers and an urban control group. Environmental monitoring inside a tram consisted in air samplings of total suspended particles (TSP), PM10 and PM2.5 carried out during November 2005. Urinary Ir levels were evaluated in 64 municipal tram drivers and in 58 administrative employees as controls. Quantification of Ir in air samples and urine was performed by means of Sector Field Inductively Coupled Plasma Mass Spectrometry. Means+/-standard deviation of Ir levels in TSP, in PM10 and PM2.5 fractions were 1.43+/-1.66, 0.44+/-0.27 and 0.36+/-0.19 pg m(-3), respectively. No statistically significant differences were observed among urinary Ir values in the exposed subjects and control group. The Ir levels in Rome air are still sufficiently low, even if the increased use of new Ir-based catalysts could be of some concern in the near future. The results of our study are of interest as they are a first attempt to explore airborne levels and urinary concentrations of Ir in an urban context at medium-high density of vehicle traffic. Particular attention should be given to the fact that Ir was found in the finest dust particles as the effects of fine particles containing Ir have not yet been studied.
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Affiliation(s)
- Ivo Iavicoli
- Institute of Occupational Medicine, Università Cattolica del Sacro Cuore, Largo Francesco Vito 1, 00168 Rome, Italy
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Firestone RB, West A, Kennett JP, Becker L, Bunch TE, Revay ZS, Schultz PH, Belgya T, Kennett DJ, Erlandson JM, Dickenson OJ, Goodyear AC, Harris RS, Howard GA, Kloosterman JB, Lechler P, Mayewski PA, Montgomery J, Poreda R, Darrah T, Hee SSQ, Smith AR, Stich A, Topping W, Wittke JH, Wolbach WS. Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling. Proc Natl Acad Sci U S A 2007; 104:16016-21. [PMID: 17901202 PMCID: PMC1994902 DOI: 10.1073/pnas.0706977104] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A carbon-rich black layer, dating to approximately 12.9 ka, has been previously identified at approximately 50 Clovis-age sites across North America and appears contemporaneous with the abrupt onset of Younger Dryas (YD) cooling. The in situ bones of extinct Pleistocene megafauna, along with Clovis tool assemblages, occur below this black layer but not within or above it. Causes for the extinctions, YD cooling, and termination of Clovis culture have long been controversial. In this paper, we provide evidence for an extraterrestrial (ET) impact event at approximately equal 12.9 ka, which we hypothesize caused abrupt environmental changes that contributed to YD cooling, major ecological reorganization, broad-scale extinctions, and rapid human behavioral shifts at the end of the Clovis Period. Clovis-age sites in North American are overlain by a thin, discrete layer with varying peak abundances of (i) magnetic grains with iridium, (ii) magnetic microspherules, (iii) charcoal, (iv) soot, (v) carbon spherules, (vi) glass-like carbon containing nanodiamonds, and (vii) fullerenes with ET helium, all of which are evidence for an ET impact and associated biomass burning at approximately 12.9 ka. This layer also extends throughout at least 15 Carolina Bays, which are unique, elliptical depressions, oriented to the northwest across the Atlantic Coastal Plain. We propose that one or more large, low-density ET objects exploded over northern North America, partially destabilizing the Laurentide Ice Sheet and triggering YD cooling. The shock wave, thermal pulse, and event-related environmental effects (e.g., extensive biomass burning and food limitations) contributed to end-Pleistocene megafaunal extinctions and adaptive shifts among PaleoAmericans in North America.
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Affiliation(s)
- R B Firestone
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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Van Wyngaardt WM, Simpson BRS. Absolute activity measurement of the electron-capture-based radionuclides 139Ce, 125I, 192Ir and 65Zn by liquid scintillation coincidence counting. Appl Radiat Isot 2006; 64:1454-8. [PMID: 16581256 DOI: 10.1016/j.apradiso.2006.02.061] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Four radionuclides with electron-capture-based decay schemes have been directly measured by a liquid scintillation coincidence extrapolation technique. 125I, 192Ir and 65Zn were measured as part of international key comparisons held under the auspices of the International Bureau of Weights and Measures (BIPM). The 139Ce measurements formed part of a regional comparison organized by the Asia Pacific Metrology Programme (APMP). Since 139Ce decays purely by electron-capture, the basic method is described for this radionuclide. Results and difficulties encountered are discussed and uncertainty budgets are presented.
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Affiliation(s)
- W M Van Wyngaardt
- Radioactivity Standards Laboratory, CSIR NML, 15 Lower Hope Road, Rosebank 7700, Cape Town, South Africa.
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Cogan SF, Troyk PR, Ehrlich J, Plante TD. In Vitro Comparison of the Charge-Injection Limits of Activated Iridium Oxide (AIROF) and Platinum-Iridium Microelectrodes. IEEE Trans Biomed Eng 2005; 52:1612-4. [PMID: 16189975 DOI: 10.1109/tbme.2005.851503] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The charge-injection limits of activated iridium oxide electrodes (AIROF) and PtIr microelectrodes with similar geometric area and shape have been compared in vitro using a stimulation waveform that delivers cathodal current pulses with current-limited control of the electrode bias potential in the interpulse period. Charge-injection limits were compared over a bias range of 0.1-0.7 V (versus Ag/AgCl) and pulse frequencies of 20, 50, and 100 Hz. The AIROF was capable of injecting between 4 and 10 times the charge of the PtIr electrode, with a maximum value of 3.9 mC/cm2 obtained at a 0.7 V bias and 20 Hz frequency.
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Affiliation(s)
- Stuart F Cogan
- EIC Laboratories Inc, 111 Downey St, Norwood, MA 02062, USA.
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Abstract
Iridium (Ir) nanocrystals were synthesized by reducing (methylcyclopentadienyl)(1,5-cyclooctadiene)lr with hexadecanediol in the presence of four different capping ligand combinations: oleic acid and oleylamine, trioctylphosphine (TOP), tetraoctylammonium bromide (TOAB), and tetraoctylphosphonium bromide (TOPB). The oleic acid/oleylamine-capped nanocrystals were of the highest quality, with the narrowest size and shape distribution. The Ir nanocrystals were tested for their ability to catalyze the hydrogenation of 1-decene as a model reaction. The oleic acid/oleylamine and TOP-capped nanocrystals were both catalytically dead. TOAB and TOPB-coated nanocrystals both catalyzed 1-decene hydrogenation, with the TOPB-coated nanocrystals exhibiting the highest turnover frequencies. Recycling through several catalytic reactions increased the catalytic activity, presumably as a result of ligand desorption and increased exposure of the metal surface, with ligand desorption eventually leading to precipitation and significantly decreased activity.
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Affiliation(s)
- Cynthia A Stowell
- Department of Chemical Engineering, Texas Materials Institute and Center for Nano and Molecular Science and Technology, The University of Texas, Austin, Texas 78712-1062, USA
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Ges IA, Ivanov BL, Schaffer DK, Lima EA, Werdich AA, Baudenbacher FJ. Thin-film IrOx pH microelectrode for microfluidic-based microsystems. Biosens Bioelectron 2004; 21:248-56. [PMID: 16023951 DOI: 10.1016/j.bios.2004.09.021] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Revised: 08/18/2004] [Accepted: 09/14/2004] [Indexed: 11/23/2022]
Abstract
Microsensors are valuable tools to monitor cell metabolism in cell culture volumes. The present research describes the fabrication and characterization of on-chip thin-film iridium oxide pH microsensors with dimensions of 20 microm x 20 microm and 20 microm x 40 microm suitable to be incorporated into nl volumes. IrOx thin films were formed on platinum microelectrodes by electrochemical deposition in galvanostatic mode. Anodically grown iridium oxide films showed a near super-Nernstian response with a slope of -77.6+/-2 mV/pH at 22 degrees C, and linear responses within the pH range of 4-11. Freshly deposited electrodes showed response times as low as 6s. Long-term studies showed a baseline drift of 2-3 mV/month, which could easily be compensated by calibration. This work demonstrated for the first time the use of planar IrOx pH microelectrodes to measure the acidification rate of CHO and fibroblast cells in an on chip cell culture volume of 25 nl with microfluidic control.
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Affiliation(s)
- Igor A Ges
- Department of Biomedical Engineering, Vanderbilt University, 6301 Stevenson Center, VU Station B 351631, Nashville, TN 37235-1631, USA
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Rauch S, Hemond HF, Peucker-Ehrenbrink B. Source characterisation of atmospheric platinum group element deposition into an ombrotrophic peat bog. ACTA ACUST UNITED AC 2004; 6:335-43. [PMID: 15054543 DOI: 10.1039/b316547g] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Platinum, palladium, rhodium, iridium and osmium were found to be enriched relative to their expected natural concentrations in peat samples from Thoreau's Bog, an ombrotrophic peat bog in Concord, Massachusetts. The source of osmium into the bog was determined from its isotopic composition (187Os/188Os). Osmium is composed of 4% lithogenic osmium from atmospheric soil dust, 41% of anthropogenic osmium and 55% of osmium from a non-lithogenic, non anthropogenic source, with rain being a likely candidate for the latter. Significant anthropogenic and rain contributions are also expected for iridium. In contrast, platinum, palladium and rhodium are almost exclusively anthropogenic. The larger enrichments of platinum, palladium and rhodium indicate that automobile catalysts are the source of platinum group elements to Thoreau's bog. The bog is located approximately 300 m from a major road and, therefore, the occurrence of platinum elements is evidence for regional dispersion of these metals. The absence of a clear trend following the introduction of catalysts indicates that platinum group elements are not quantitatively conserved in peat with downward leaching and plants playing an important role in the accumulation of platinum group elements.
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Affiliation(s)
- Sebastien Rauch
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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Affiliation(s)
- T Thulborn
- School of Geosciences, Monash University, Box 28E, Clayton, Victoria 3800, Australia
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Akita T, Okumura M, Tanaka K, Tsubota S, Haruta M. Analytical TEM observation of Au and Ir deposited on rutile TiO2. J Electron Microsc (Tokyo) 2003; 52:119-124. [PMID: 12868582 DOI: 10.1093/jmicro/52.2.119] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
As a model catalyst, gold and iridium were co-deposited on a single crystal of rutile TiO2 using the deposition precipitation method in order to clarify the synergetic effect of the combination of Au with Ir on the catalytic performance of the oxidative decomposition of odour and dioxins. Analyses by means of high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and electron energy-loss spectroscopy revealed that pillars of IrO2 grew on the TiO2 substrate to each of which one Au nanoparticle was attached. This mushroom-like structure appeared to be formed by self-organization of Au, Ir and oxygen. Epitaxial contact was observed between the Au nanoparticle/IrO2 pillar and IrO2 pillar/TiO2 substrate interfaces. The growth process of the structure was investigated by transmission electron microscope observations of the Au-Ir complex before and after heating in air.
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Affiliation(s)
- Tomoki Akita
- National Institute of Advanced Industrial Science and Technology, Special Division for Green Life Technology, 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan.
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Olsen PE, Kent DV, Sues HD, Koeberl C, Huber H, Montanari A, Rainforth EC, Fowell SJ, Szajna MJ, Hartline BW. Ascent of dinosaurs linked to an iridium anomaly at the Triassic-Jurassic boundary. Science 2002; 296:1305-7. [PMID: 12016313 DOI: 10.1126/science.1065522] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Analysis of tetrapod footprints and skeletal material from more than 70 localities in eastern North America shows that large theropod dinosaurs appeared less than 10,000 years after the Triassic-Jurassic boundary and less than 30,000 years after the last Triassic taxa, synchronous with a terrestrial mass extinction. This extraordinary turnover is associated with an iridium anomaly (up to 285 parts per trillion, with an average maximum of 141 parts per trillion) and a fern spore spike, suggesting that a bolide impact was the cause. Eastern North American dinosaurian diversity reached a stable maximum less than 100,000 years after the boundary, marking the establishment of dinosaur-dominated communities that prevailed for the next 135 million years.
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Affiliation(s)
- P E Olsen
- Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA
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Raup DM. The role of extraterrestrial phenomena in extinction. Rev Esp Paleontol 2001; 1988:99-106. [PMID: 11542144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
In the several years since the Alvarez report of anomalously high iridium concentrations at the Cretaceous-Tertiary boundary, evidence for the involvement of meteorite impacts in biological extinction has increased dramatically. Much more research will be needed, however, before meteorite impact is established as a general causal factor in extinction. Of ever greater long-term interest is the possibility that other extraterrestrial forces have had important influences on the evolution of life. To recognize the effects of such forces, it will be necessary to coordinate the research of astronomy and paleontology so that testable predictions can be formulated. It is possible that known, systematic changes in the Solar System or Galaxy have had effects on global biology and that these effects have been preserved in the paleontological record.
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Affiliation(s)
- D M Raup
- Department of Geophysical Sciences, University of Chicago, Illinois 60637, USA
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Abstract
A health risk assessment of platinum (Pt) emitted from automotive catalytic converters is presented. Following a stepwise approach, the relevant literature is discussed in order to characterize Pt emissions as well as the toxic potential of Pt and its compounds. In an exposure assessment, ambient Pt concentrations in air are predicted to range from approximately 4 pg/m3 (street canyon, typical conditions) up to approximately 112 pg/m3 (express motorway, severe conditions). These values agree well with the few measured concentrations, which are also in the low pg/m3 range. Pt is emitted from catalytic converters in very small amounts (ng/km range), mainly in the (0)-oxidation state (elemental Pt). The nanocrystalline Pt particles are attached to microm-sized aluminum oxide particles. Whether free ultrafine Pt particles may be emitted and result in biological effects has not been studied sufficiently. Hence, risk assessment can only be based on the respiratory sensitizing potential of halogenated Pt salts. The presence of such compounds in automotive Pt emissions cannot definitely be excluded. From recent occupational studies conducted in catalytic converter production, a conservative no-effect level (NOEL) of 1.5 ng/m3 can be derived for the sensitizing effect of halogenated Pt salts. In a (reasonable) worst case approach, it is assumed that such compounds comprise 1% (0.1%) of the total Pt emissions. Applying a safety factor of 10 to account for interindividual variability, a guidance value of 15 (150) ng/m3 is derived for catalyst-borne Pt. The exposure to Pt in ambient air as measured or predicted is at least two orders of magnitude below this guidance range. Rhodium is also contained in automotive catalysts, palladium has increasingly substituted Pt, and iridium-based catalysts have recently been introduced. Although the database on these platinum group metals is rather small, there is no evidence that they pose a health risk to the general population.
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Affiliation(s)
- R Merget
- Department of Internal Medicine, University Hospital Bergmannsheil, Bochum, Germany
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Abstract
Since 1982, numerous indicators of catastrophic events have been observed at the main stratigraphic boundaries in China during the Phanerozoic, i.e. Precambrian-Cambrian, Permian-Triassic, Cretaceous-Tertiary as well as Ordovician-Silurian and Devonian-Carboniferous boundaries. These markers are boundary clay layer, microspherules, high Ir anomaly, mass extinction of organisms and impact of meteorite. We support the hypothesis of the extraterrestrial origin of catastrophic events and suggest that the events at different stratigraphic boundaries might be different in features and processes.
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Affiliation(s)
- Q Zhang
- Institute of Geology, State Seismological Bureau, Beijing, China
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Ramadurai S, Lloyd D, Wallis M, Wickramasinghe NC. Extinction of dinosaurs: a possible novel cause. Adv Space Res 1995; 15:139-146. [PMID: 11539216 DOI: 10.1016/s0273-1177(99)80075-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A novel cause of mass extinction of fauna close to the (K/T) Boundary is suggested. A large amount of non-protein amino acids (AIB and ISOVAL) has been observed close to this event. It is speculated that these amino acids may be toxic and are responsible for the extinction. The toxicity level is estimated for this suggestion to be true and experimentalists are encouraged to test this level of toxicity for the amino acids.
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Affiliation(s)
- S Ramadurai
- Tata Institute of Fundamental Research, Bombay, India
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Alvarez W, Smit J, Lowrie W, Asaro F, Margolis SV, Claeys P, Kastner M, Hildebrand AR. Proximal impact deposits at the Cretaceous-Tertiary boundary in the Gulf of Mexico: a restudy of DSDP Leg 77 Sites 536 and 540. Geology 1992; 20:697-700. [PMID: 11538163 DOI: 10.1130/0091-7613(1992)020<0697:pidatc>2.3.co;2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Restudy of Deep Sea Drilling Project Sites 536 and 540 in the southeast Gulf of Mexico gives evidence for a giant wave at Cretaceous-Tertiary boundary time. Five units are recognized: (1) Cenomanian limestone underlies a hiatus in which the five highest Cretaceous stages are missing, possibly because of catastrophic K-T erosion. (2) Pebbly mudstone, 45 m thick, represents a submarine landslide possibly of K-T age. (3) Current-bedded sandstone, more than 2.5 m thick, contains anomalous iridium, tektite glass, and shocked quartz; it is interpreted as ejecta from a nearby impact crater, reworked on the deep-sea floor by the resulting tsunami. (4) A 50-cm interval of calcareous mudstone containing small Cretaceous planktic foraminifera and the Ir peak is interpreted as the silt-size fraction of the Cretaceous material suspended by the impact-generated wave. (5) Calcareous mudstone with basal Tertiary forams and the uppermost tail of the Ir anomaly overlies the disturbed interval, dating the impact and wave event as K-T boundary age. Like Beloc in Haiti and Mimbral in Mexico, Sites 536 and 540 are consistent with a large K-T age impact at the nearby Chicxulub crater.
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Affiliation(s)
- W Alvarez
- Department of Geology and Geophysics, University of California, Berkeley 94720, USA
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Abstract
We report detailed analyses on the concentrations of the noble metals Pd, Os, Ir, Pt, and Au in an early Archean spherule bed (S4) of probable impact origin from the lower Fig Tree Group, Barberton Greenstone Belt, South Africa. Compared to other sedimentary deposits of known or suspected impact origin, some noble metals are present in exceptionally high concentrations. Noble metal abundances are fractionated relative to abundances in chondrites with ratios of Os/Ir, Pt/Ir, Pd/Ir, and Au/Ir at only 80, 80, 41, and 2% of these values in CI chondrites. Although an extraterrestrial source is favored for the noble metal enrichment, the most plausible cause of the fractionation is by regional hydrothermal/metasomatic alteration.
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Affiliation(s)
- F T Kyte
- Institute of Geophysics and Planetary Physics, University of California, Los Angeles 90024
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Abstract
The iridium anomaly at the Cretaceous-Tertiary (KT) boundary was discovered in the pelagic limestone sequence at Gubbio on the basis of 12 samples analyzed by neutron activation analysis (NAA) and was interpreted as indicating impact of a large extraterrestrial object at exactly the time of the KT mass extinction. Continuing controversy over the shape of the Ir profile at the Gubbio KT boundary and its interpretation called for a more detailed follow-up study. Analysis of a 57-meter-thick, 10-million-year-old part of the Gubbio sequence using improved NAA techniques revealed that there is only one Ir anomaly at the KT boundary, but this anomaly shows an intricate fine structure, the origin of which cannot yet be entirely explained. The KT Ir anomaly peaks in a 1-centimeter-thick clay layer, where average Ir concentration is 3000 parts per trillion (ppt); this peak is flanked by tails with Ir concentrations of 20 to 80 ppt that rise above a background of 12 to 13 ppt. The fine structure of the tails is probably due in part to lateral reworking, diffusion, burrowing, and perhaps Milankovitch cyclicity.
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Affiliation(s)
- W Alvarez
- Department of Geology and Geophysics, University of California, Berkeley 94720, USA
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Alvarez W, Asaro F. An extraterrestrial impact (accumulating evidence suggests an asteroid or comet caused the Cretaceous extinction). Sci Am 1990; 263:78-84. [PMID: 11536473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Affiliation(s)
- W Alvarez
- University of California, Berkeley, USA
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Abstract
Evidence indicates that the collisions of Earth and a large piece of Solar System debris such as a meteoroid, asteroid or comet caused the great extinctions of 65 million years ago, leading to the transition from the age of the dinosaurs to the age of the mammals.
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Affiliation(s)
- L W Alvarez
- Lawrence Berkeley Laboratory, University of California, Berkeley, USA
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Arcovito G, Piermattei A, Bacci C, Pittella G, Castagnola M. [Rigid phantom dosimetry of brachytherapy sources, with special reference to 125-I]. Radiol Med 1985; 71:426-32. [PMID: 4070702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
At present, the brachytherapy dosimetry requires the highest level of accuracy in determining the physical parameters of many different radiation sources. Brachytherapy sources differ not only in the nucleus (widely ranging between 30 keV and 1 MeV), but also in the strength and geometrical and filtration characteristics. This work reports the brachytherapy dosimetry carried out in a rigid perspex phantom which allows measurements by means of solid state dosimeters (TLD, semiconductor), ionization chamber and film. Film densities were measured by means of a computerized Perkin-Elmer 1010G microdensitometer, with a spatial resolution of 50 microns. The isodensity lines were dose calibrated by TLD measurements. The dosimetry of the 125I, 192Ir and 198Au sources is reported. The dose distributions of the low energy 125I source, in two different tissues (muscle and adipose) were studied, by means of laboratory built tissue-equivalent sections of the phantoms. The experimental data suggest that this dosimetric procedure is suitable for intercomparison measurements between different radiotherapy centers using the same nuclides in different sources.
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Abstract
After reviewing the method of Hall et coll. (1966) for calculating dose rates from 192Ir wire, small changes and improvements were made and a computer program was written to calculate dose distributions. It was found that the wire position data obtained from films and supplied to the program was the largest source of inaccuracy but that with care the maximum error in the calculated dose rates was 3 per cent. If the original cross-line curves are still used for calculations the additional error introduced into the dose rates at distances of up to 4 cm from the wire is less than one per cent.
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Kruszyna H, Kruszyna R, Hurst J, Smith RP. Toxicology and pharmacology of some ruthenium compounds: Vascular smooth muscle relaxation by nitrosyl derivatives of ruthenium and iridium. J Toxicol Environ Health 1980; 6:757-73. [PMID: 7420479 DOI: 10.1080/15287398009529895] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A series of compounds were synthesized from ruthenium trichloride, and their ip LD50s were determined in mice: pentamminenitrosylruthenium(II) chloride, 8.9; chloronitrobis(2,2'-dipyridyl)ruthenium(II), 55;dichlorobis(2,2'-dipyridyl)ruthenium(II), 63; ruthenium trichloride, 108; and potassium pentachloronitrosylruthenate(II), 127 mg/kg. The two bis-bipyridyl complexes produced death in convulsions within minutes, whereas the remaining compounds resulted in long, debilitating courses with death occurring in 4-7d. When given in massive overdoses, however, the compounds with inorganic ligands also produced rapid convulsive death in mice, and when given iv to anesthetized cats, they produced respiratory arrest. The major toxic effects of all the complexes appeared to be due to the metal and not to its associated ligands. Only complexes having nitrosyl ligand specifically relaxed vascular smooth muscle. Potassium pentabromoiridate(III) also relaxed rabbit aortic strips that had been contracted by adrenergic agonists, but potassium pentachloroiridate(III) did not. None of the complexes was as active as nitroprusside in relaxing aortic strips or in decreasing arterial blood pressure in cats. No compound tested was as potent as cisplatin in antitumor activity. The pentamminenitrosylruthenium(II) complex also relaxed guinea pig ileum and frog rectus abdominus when these isolated muscles had been contracted by acetylcho line. It appears that these organoruthenium compounds may produce death in central respiratory arrest, as do the inorganic complexes when given iv or ip in massive overdoses. In minimally lethal doses, the complexes with inorganic ligands may affect a variety of contractile tissues, perhaps by a general mechanism involving Ca. These complexes are apt to be generally cytotoxic as well.
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Abstract
A method for the systematic activation analysis of seven noble metals--ruthenium, silver, rhenium, osmium, iridium, platinum and gold--in rocks were developed and examined with radiotracers and irradiated rock samples. After the fusion of the irradiated rock sample with sodium hydroxide and sodium peroxide, 10% sodium sulfide solution is added and rhenium is extracted with pyridine-benzene mixture from 6N sodium hydroxide solution. From the hydroxide-sulfide precipitate fraction, ruthenium and osmium are distilled as tetroxides, silver is precipitated as chloride, gold is extracted with ethyl acetate, and iridium and platinum are extracted with diantipyrylmethane. Each fraction is purified and subjected to the gamma-ray spectrometry. Chemical yields for the elements are more than 60%. Determination limits are given for the seven elements.
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Zinchenko TV, Miakushko TI. [Study of hedge nettles of the Ukraine (the genus Stachys L.)]. Farm Zh 1972; 27:64-8. [PMID: 4664027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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