Platinum group elements geochemistry of ultramafic and associated ...

Indian Academy of Sciences (India)

group element (PGE) and associated gold mineralization in these ultramafic rocks. A mineral ... Paleoproterozoic age, mostly emplaced into the .... tified reference materials (CRM) from the US Geo- ..... Classification diagram (Barnes et al.

The platinum group elements and gold: analysis by radiochemical and instrumental neutron activation analysis and relevance to geological exploration and related problems

Energy Technology Data Exchange (ETDEWEB)

Reeves, S; Plimer, I R [Melbourne Univ., Parkville, VIC (Australia). School of Physics

1997-12-31

This paper presents an overview of research conducted with the support of the Australian Institute of Nuclear Science and Engineering, at the University of Melbourne, School of Earth Sciences, Radiochemical Neutron Activation Laboratory. The primary objective of this research is to realize the high potential of the platinum group elements (PGE) and gold to the solution of petrogenetic problems, the study of magma generation and magmatic processes in mafic/ultramafic rock suites, as tracers in hydrothermal ore formation. The PGEs (Os, Ru, Ir, Pt, Pd and Rh) are among the least abundant of all elements on earth with unique properties such as high melting points, high electrical and thermal conductivity, high density, strength and toughness as alloys. They exhibit both siderophile and chalcophile characteristics and are valuable tools in providing information about magmatic processes, in particular S-saturation, as well as crystal fractionation trends. Two distinct groups of PGEs are discerned; the IPGEs (Ru, Os, Ir) and the PPGEs (Pt, Pd, Rh, Au) on the basis of their behaviour during fractionation processes. Using chondrite normalized PGE patterns it is possible to distinguish between sulphides that segregated from primitive magmas, such as komatiites, and sulphides which segregated from more fractionated magmas, such as tholeiites. It is critical to the understanding of these processes to be able to analyse key elements, such as the PGE and gold, in the parts per billion to parts per trillion range. Platinum group elements and Au were determined by radiochemical neutron activation analysis using a modified NiS fire-assay preconcentration technique, adapted from procedures first used by Robert, R.V. D. and van Wyk, E. (1975) . Detection limits are generally 0.005-0.01 ppb (Au and Ir), 0.1-0.2 ppb (Pd and Pt), and 0.1-0.5 ppb for Ru. 9 refs.

The platinum group elements and gold: analysis by radiochemical and instrumental neutron activation analysis and relevance to geological exploration and related problems

Energy Technology Data Exchange (ETDEWEB)

Reeves, S.; Plimer, I. R. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

1996-12-31

This paper presents an overview of research conducted with the support of the Australian Institute of Nuclear Science and Engineering, at the University of Melbourne, School of Earth Sciences, Radiochemical Neutron Activation Laboratory. The primary objective of this research is to realize the high potential of the platinum group elements (PGE) and gold to the solution of petrogenetic problems, the study of magma generation and magmatic processes in mafic/ultramafic rock suites, as tracers in hydrothermal ore formation. The PGEs (Os, Ru, Ir, Pt, Pd and Rh) are among the least abundant of all elements on earth with unique properties such as high melting points, high electrical and thermal conductivity, high density, strength and toughness as alloys. They exhibit both siderophile and chalcophile characteristics and are valuable tools in providing information about magmatic processes, in particular S-saturation, as well as crystal fractionation trends. Two distinct groups of PGEs are discerned; the IPGEs (Ru, Os, Ir) and the PPGEs (Pt, Pd, Rh, Au) on the basis of their behaviour during fractionation processes. Using chondrite normalized PGE patterns it is possible to distinguish between sulphides that segregated from primitive magmas, such as komatiites, and sulphides which segregated from more fractionated magmas, such as tholeiites. It is critical to the understanding of these processes to be able to analyse key elements, such as the PGE and gold, in the parts per billion to parts per trillion range. Platinum group elements and Au were determined by radiochemical neutron activation analysis using a modified NiS fire-assay preconcentration technique, adapted from procedures first used by Robert, R.V. D. and van Wyk, E. (1975) . Detection limits are generally 0.005-0.01 ppb (Au and Ir), 0.1-0.2 ppb (Pd and Pt), and 0.1-0.5 ppb for Ru. 9 refs.

The platinum group elements and gold: analysis by radiochemical and instrumental neutron activation analysis and relevance to geological exploration and related problems

International Nuclear Information System (INIS)

Reeves, S.; Plimer, I. R.

1996-01-01

This paper presents an overview of research conducted with the support of the Australian Institute of Nuclear Science and Engineering, at the University of Melbourne, School of Earth Sciences, Radiochemical Neutron Activation Laboratory. The primary objective of this research is to realize the high potential of the platinum group elements (PGE) and gold to the solution of petrogenetic problems, the study of magma generation and magmatic processes in mafic/ultramafic rock suites, as tracers in hydrothermal ore formation. The PGEs (Os, Ru, Ir, Pt, Pd and Rh) are among the least abundant of all elements on earth with unique properties such as high melting points, high electrical and thermal conductivity, high density, strength and toughness as alloys. They exhibit both siderophile and chalcophile characteristics and are valuable tools in providing information about magmatic processes, in particular S-saturation, as well as crystal fractionation trends. Two distinct groups of PGEs are discerned; the IPGEs (Ru, Os, Ir) and the PPGEs (Pt, Pd, Rh, Au) on the basis of their behaviour during fractionation processes. Using chondrite normalized PGE patterns it is possible to distinguish between sulphides that segregated from primitive magmas, such as komatiites, and sulphides which segregated from more fractionated magmas, such as tholeiites. It is critical to the understanding of these processes to be able to analyse key elements, such as the PGE and gold, in the parts per billion to parts per trillion range. Platinum group elements and Au were determined by radiochemical neutron activation analysis using a modified NiS fire-assay preconcentration technique, adapted from procedures first used by Robert, R.V. D. and van Wyk, E. (1975) . Detection limits are generally 0.005-0.01 ppb (Au and Ir), 0.1-0.2 ppb (Pd and Pt), and 0.1-0.5 ppb for Ru. 9 refs

Concentrations of Platinum Group Elements (Pt, Pd, Rh) in Airborne Particulate Matter (PM2.5 and PM10-2.5) Collected at Selected Canadian Urban Sites: a Case Study

OpenAIRE

Celo V.; Zhao J. J.; Dabek-Zlotorzynska E.

2013-01-01

Increasing environmental concentrations of platinum group elements (PGEs), in particular platinum (Pt), palladium (Pd) and rhodium (Rh), from catalytic converters has been reported worldwide. Initially it was believed that the emitted PGEs remain in the roadside environment, but recent studies have shown that fine PGE-containing particles can be transported and distributed at regional and long-range levels. Therefore, the monitoring of PGEs in airborne particulate matter (PM) is important for...

Investigations on the bioavailability of traffic-related platinum group elements (PGE) to the aquatic fauna with special consideration being given to palladium; Untersuchungen zur Bioverfuegbarkeit Kfz-emittierter Platingruppenelemente (PGE) fuer die aquatische Fauna unter besonderer Beruecksichtigung von Palladium

Energy Technology Data Exchange (ETDEWEB)

Sures, B.; Thielen, F.; Zimmermann, S. [Karlsruhe Univ. (T.H.) (Germany). Zoologisches Inst.

2002-07-01

The uptake and accumulation of the traffic-related platinum group elements (PGE) Pt, Pd and Rh by the aquatic fauna was investigated. Zebra mussels, eels and barbels were maintained in water containing either road dust or ground catalytic converter material. Following the exposure, samples of fish liver and kidney, as well as the soft tissues of the mussels, were analysed. Our results revealed that all three catalytic noble metals were accumulated by aquatic organisms. The highest bioavailability was found for Pd, followed by Pt and Rh. The concentration factor of Pd for Dreissena polymorpha was 5 times higher compared with Pb and only 6 times lower than the essential element Cu. With regard to the increasing emission of Pd the level of this metal has to be monitored very carefully in the environment. (orig.) [German] Die Aufnahme und Anreicherung der Kfz-buertigen Platingruppenelemente (PGE) Pt, Pd und Rh durch aquatische Tiere wurde an Dreikantmuscheln, Aalen und Barben untersucht. Hierzu wurden die Testorganismen in Wasser mit Strassenstaub einer stark befahrenen Strasse oder mit zerriebenem Autokatalysatormaterial ueber mehrere Wochen exponiert und anschliessend Leber und Niere der Fische sowie das Weichgewebe der Muscheln analysiert. Im Rahmen dieser Studien konnte nachgewiesen werden, dass alle drei Edelmetalle durch Fische wie durch Muscheln aufgenommen und angereichert werden. Fuer Pd fand sich die hoechste Bioverfuegbarkeit, gefolgt von Pt und Rh. Das Ausmass der Aufnahme von Pd durch Dreissena polymorpha war ca. 5fach hoeher als von Pb und 6fach niedriger verglichen mit dem essenziellen Element Cu. In Anbetracht der steigenden Emission von Pd sollte ein Umweltmonitoring die Verbreitung von Pd in der Umwelt klaeren. (orig.)

The use of cation exchange matrix separation coupled with ICP-MS to directly determine platinum group element (PGE) and other trace element emissions from passenger cars equipped with diesel particulate filters (DPF)

Energy Technology Data Exchange (ETDEWEB)

Cairns, Warren R.L.; Cozzi, Giulio [Institute for the Dynamics of Environmental Processes-CNR, Venice (Italy); De Boni, Antonella; Gabrieli, Jacopo [University of Venice, Department of Environmental Science, Venice (Italy); Asti, Massimo; Merlone Borla, Edoardo; Parussa, Flavio [Centro Ricerche Fiat, Orbassano (Italy); Moretto, Ezio [FIAT Powertrain Technologies S.p.A, Turin (Italy); Cescon, Paolo; Barbante, Carlo [University of Venice, Department of Environmental Science, Venice (Italy); Institute for the Dynamics of Environmental Processes-CNR, Venice (Italy); Boutron, Claude [Laboratoire de Glaciologie et Geophysique de l' Environnement, UMR CNRS 5183, B.P. 96, Saint Martin d' Heres Cedex (France)

2011-03-15

Inductively coupled plasma-mass spectrometry coupled with cation exchange matrix separation has been optimised for the direct determination of platinum group element (PGE) and trace element emissions from a diesel engine car. After matrix separation method detection limits of 1.6 ng g{sup -1} for Pd, 0.4 ng g{sup -1} for Rh and 4.3 ng g{sup -1} for Pt were achieved, the method was validated against the certified reference material BCR 723, urban road dust. The test vehicle was fitted with new and aged catalytic converters with and without diesel particulate filters (DPF). Samples were collected after three consecutive New European Driving Cycle (NEDC) of the particulate and ''soluble'' phases using a home-made sampler optimised for trace element analysis. Emission factors for the PGEs ranged from 0.021 ng km{sup -1} for Rh to 70.5 ng km{sup -1} for Pt; when a DPF was fitted, the emission factors for the PGEs actually used in the catalysts dropped by up to 97% (for Pt). Trace element emission factors were found to drop by a maximum of 92% for Ni to a minimum of 18% for Y when a DPF was fitted; a new DPF was also found to cause a reduction of up to 86% in the emission of particulate matter. (orig.)

Platinum-group elements and gold in base metal sulfides, platinum-group minerals, and Re-Os isotope compositions of the Uitkomst complex, South Africa

Czech Academy of Sciences Publication Activity Database

Trubač, Jakub; Ackerman, Lukáš; Gauert, Ch.; Ďurišová, Jana; Hrstka, Tomáš

2018-01-01

Roč. 113, č. 2 (2018), s. 439-461 ISSN 0361-0128 R&D Projects: GA ČR GA13-15390S Institutional support: RVO:67985831 Keywords : binary alloys * copper compounds * economic geology * gold * iridium * isotopes * ore deposits * osmium * palladium * platinum * platinum metals * pyrites * Rhenium * rhenium alloys * ruthenium * solid solutions * sulfur compounds * crustal materials * mass-balance calculations * massive sulfides * mineralized zone * monosulfide solid solutions * platinum group elements * platinum group elements (PGEs) * platinum group minerals Subject RIV: DB - Geology ; Mineralogy; AC - Archeology, Anthropology, Ethnology (ARUB-Q) OBOR OECD: Geology; Archaeology (ARUB-Q) Impact factor: 2.519, year: 2016

Empirical constraints on partitioning of platinum group elements between Cr-spinel and primitive terrestrial magmas

Science.gov (United States)

Park, Jung-Woo; Kamenetsky, Vadim; Campbell, Ian; Park, Gyuseung; Hanski, Eero; Pushkarev, Evgeny

2017-11-01

Recent experimental studies and in situ LA-ICP-MS analysis on natural Cr-spinel have shown that Rh and IPGEs (Ir-group platinum group elements: Ru, Ir, Os) are enriched in the lattice of Cr-spinel. However, the factors controlling the partitioning behaviour of these elements are not well constrained. In this study, we report the Rh, IPGE, and trace element contents in primitive Cr-spinel, measured by LA-ICP-MS, from nine volcanic suites covering various tectonic settings including island arc picrites, boninites, large igneous province picrites and mid-ocean ridge basalts. The aim is to understand the factors controlling the enrichment of Rh and IPGEs in Cr-spinels, to estimate empirical partition coefficients between Cr-spinel and silicate melts, and to investigate the role of Cr-spinel fractional crystallization on the PGE geochemistry of primitive magmas during the early stages of fractional crystallization. There are systematic differences in trace elements, Rh and IPGEs in Cr-spinels from arc-related magmas (Arc Group Cr-spinel), intraplate magmas (Intraplate Group Cr-spinel), and mid-ocean ridge magmas (MORB Group Cr-spinel). Arc Group Cr-spinels are systematically enriched in Sc, Co and Mn and depleted in Ni compared to the MORB Group Cr-spinels. Intraplate Group Cr-spinels are distinguished from the Arc Group Cr-spinels by their high Ni contents. Both the Arc and Intraplate Group Cr-spinels have total Rh and IPGE contents of 22-689 ppb whereas the MORB Group Cr-spinels are depleted in Rh and IPGE (total time-resolved spectra of LA-ICP-MS data for Cr-spinels mostly show constant count rates for trace element and Rh and IPGEs, suggesting homogeneous distribution of these elements in Cr-spinels. The PGE spikes observed in several Cr-spinels were interpreted to be PGE-bearing mineral inclusions and excluded from calculating the PGE contents of the Cr-spinels. On primitive mantle normalized diagrams the Arc Group Cr-spinels are characterized by a fractionated

New exploration methods for platinum and rhodium deposits poor in base-metal sulphides

DEFF Research Database (Denmark)

Ohnenstetter, M.; Johan, Z.; Cocherie, A.

1999-01-01

Platinum-group elements (PGE) are typically associated with mafic and ultramafic intrusive rocks and the main exploration targets are layers and zones rich in PGE-bearing sulphides. Some PGE occurences, however, are in sulphide-poor situations and this raises the possibility that PGE deposits may...

Occurrence model for magmatic sulfide-rich nickel-copper-(platinum-group element) deposits related to mafic and ultramafic dike-sill complexes: Chapter I in Mineral deposit models for resource assessment

Science.gov (United States)

Schulz, Klaus J.; Woodruff, Laurel G.; Nicholson, Suzanne W.; Seal, Robert R.; Piatak, Nadine M.; Chandler, Val W.; Mars, John L.

2014-01-01

Magmatic sulfide deposits containing nickel (Ni) and copper (Cu), with or without (±) platinum-group elements (PGE), account for approximately 60 percent of the world’s nickel production. Most of the remainder of the Ni production is derived from lateritic deposits, which form by weathering of ultramafic rocks in humid tropical conditions. Magmatic Ni-Cu±PGE sulfide deposits are spatially and genetically related to bodies of mafic and/or ultramafic rocks. The sulfide deposits form when the mantle-derived mafic and/or ultramafic magmas become sulfide-saturated and segregate immiscible sulfide liquid, commonly following interaction with continental crustal rocks.

High salinity volatile phases in magmatic Ni-Cu-platinum group element deposits

Science.gov (United States)

Hanley, J. J.; Mungall, J. E.

2004-12-01

The role of "deuteric" fluids (exsolved magmatic volatile phases) in the development of Ni-Cu-PGE (platinum group element) deposits in mafic-ultramafic igneous systems is poorly understood. Although considerable field evidence demonstrates unambiguously that fluids modified most large primary Ni-Cu-PGE concentrations, models which hypothesize that fluids alone were largely responsible for the economic concentration of the base and precious metals are not widely accepted. Determination of the trace element composition of magmatic volatile phases in such ore-forming systems can offer considerable insight into the origin of potentially mineralizing fluids in such igneous environments. Laser ablation ICP-MS microanalysis allows researchers to confirm the original metal budget of magmatic volatile phases and quantify the behavior of trace ore metals in the fluid phase in the absence of well-constrained theoretical or experimental predictions of ore metal solubility. In this study, we present new evidence from major deposits (Sudbury, Ontario, Canada; Stillwater Complex, Montana, U.S.A.) that compositionally distinct magmatic brines and halide melt phases were exsolved from crystallizing residual silicate melt and trapped within high-T fluid conduits now comprised of evolved rock compositions (albite-quartz graphic granite, orthoclase-quartz granophyre). Petrographic evidence demonstrates that brines and halide melts coexisted with immiscible carbonic phases at the time of entrapment (light aliphatic hydrocarbons, CO2). Brine and halide melt inclusions are rich in Na, Fe, Mn, K, Pb, Zn, Ba, Sr, Al and Cl, and homogenize by either halite dissolution at high T ( ˜450-700° C) or by melting of the salt phase (700-800° C). LA-ICPMS analyses of single inclusions demonstrate that high salinity volatile phases contained abundant base metals (Cu, Fe, Sn, Bi) and precious metals (Pt, Pd, Au, Ag) at the time of entrapment. Notably, precious metal concentrations in the inclusions

Fibrous Platinum-Group Minerals in “Floating Chromitites” from the Loma Larga Ni-Laterite Deposit, Dominican Republic

Directory of Open Access Journals (Sweden)

Thomas Aiglsperger

2016-11-01

Full Text Available This contribution reports on the observation of enigmatic fibrous platinum-group minerals (PGM found within a chromitite body included in limonite (“floating chromitite” from Ni-laterites in the Dominican Republic. Fibrous PGM have a Ru-Os-Ir-Fe dominated composition and are characterized by fibrous textures explained by grain-forming fibers which are significantly longer (1–5 µm than they are wide (~100 nm. Back-scattered electron (BSE images suggest that these nanofibers are platinum-group elements (PGE-bearing and form <5 µm thick layers of bundles which are oriented orthogonal to grains’ surfaces. Trace amounts of Si are most likely associated with PGE-bearing nanofibers. One characteristic fibrous PGM was studied in detail: XRD analyses point to ruthenian hexaferrum. However, the unpolished fibrous PGM shows numerous complex textures on its surface which are suggestive for neoformation processes: (i features suggesting growth of PGE-bearing nanofibers; (ii occurrence of PGM nanoparticles within film material (biofilm? associated with PGE-bearing nanofibers; (iii a Si-rich and crater-like texture hosting PGM nanoparticles and an Ir-rich accumulation of irregular shape; (iv complex PGM nanoparticles with ragged morphologies, resembling sponge spicules and (v oval forms (<1 µm in diameter with included PGM nanoparticles, similar to those observed in experiments with PGE-reducing bacteria. Fibrous PGM found in the limonite may have formed due to supergene (bio-weathering of fibrous Mg-silicates which were incorporated into desulphurized laurite during stages of serpentinization.

Platinum-group element geochemistry used to determine Cu and Au fertility in the Northparkes igneous suites, New South Wales, Australia

Science.gov (United States)

Hao, Hongda; Campbell, Ian H.; Park, Jung-Woo; Cooke, David R.

2017-11-01

Recent studies have shown that platinum-group elements (PGE) can be used to constrain the timing of sulfide saturation in evolving felsic systems. In this study, we report trace-element, PGE, Re and Au data for the barren and ore-associated suites of intermediate to felsic rocks from the Northparkes Cu-Au porphyry region, emphasizing the timing of sulfide saturation and its influence on the tenor of the associated hydrothermal mineralization. Two barren suites, the Goonumbla and Wombin Volcanics and associate intrusive rocks, are found in the region. Geochemical modelling shows that the barren suites are dominated by plagioclase-pyroxene fractionation, whereas the ore-associated Northparkes Cu-Au porphyry suite is characterized by plagioclase-amphibole fractionation, which requires the ore-bearing suite to have crystallized from a wetter magma than barren suites. The concentrations of PGE, Re and Au in the barren suites decrease continuously during fractional crystallization. This is attributed to early sulfide saturation with the fraction of immiscible sulfide precipitation required to produce the observed trend, being 0.13 and 0.16 wt.% for the Goonumbla and Wombin suites, respectively. The calculated partition coefficients for Au and Pd required to model the observed change in these elements with MgO are well below published values, indicating that R, the mass ratio of silicate to sulfide melt, played a significant role in controlling the rate of decline of these elements with fractionation. Palladium in the ore-associated suite, in contrast, first increases with fractionation then decreases abruptly at 1.2 wt.% MgO. The sharp decrease is attributed to the onset of sulfide precipitation. Platinum on the other hand shows a moderate decrease, starting from the highest MgO sample analysed, but then decreasing strongly from 1.2 wt.% MgO. The initial Pt decrease is attributed to precipitation of a platinum-group mineral (PGM), probably a Pt-Fe alloy, and the sharp

Re-Os isotope and platinum group elements of a FOcal ZOne mantle source, Louisville Seamounts Chain, Pacific ocean

Science.gov (United States)

Tejada, Maria Luisa G.; Hanyu, Takeshi; Ishikawa, Akira; Senda, Ryoko; Suzuki, Katsuhiko; Fitton, Godfrey; Williams, Rebecca

2015-02-01

The Louisville Seamount Chain (LSC) is, besides the Hawaiian-Emperor Chain, one of the longest-lived hotspot traces. We report here the first Re-Os isotope and platinum group element (PGE) data for Canopus, Rigil, and Burton Guyots along the chain, which were drilled during IODP Expedition 330. The LSC basalts possess (187Os/188Os)i = 0.1245-0.1314 that are remarkably homogeneous and do not vary with age. A Re-Os isochron age of 64.9 ± 3.2 Ma was obtained for Burton seamount (the youngest of the three seamounts drilled), consistent with 40Ar-39Ar data. Isochron-derived initial 187Os/188Os ratio of 0.1272 ± 0.0008, together with data for olivines (0.1271-0.1275), are within the estimated primitive mantle values. This (187Os/188Os)i range is similar to those of Rarotonga (0.124-0.139) and Samoan shield (0.1276-0.1313) basalts and lower than those of Cook-Austral (0.136-0.155) and Hawaiian shield (0.1283-0.1578) basalts, suggesting little or no recycled component in the LSC mantle source. The PGE data of LSC basalts are distinct from those of oceanic lower crust. Variation in PGE patterns can be largely explained by different low degrees of melting under sulfide-saturated conditions of the same relatively fertile mantle source, consistent with their primitive mantle-like Os and primordial Ne isotope signatures. The PGE patterns and the low 187Os/188Os composition of LSC basalts contrast with those of Ontong Java Plateau (OJP) tholeiites. We conclude that the Re-Os isotope and PGE composition of LSC basalts reflect a relatively pure deep-sourced common mantle sampled by some ocean island basalts but is not discernible in the composition of OJP tholeiites.

Platinum group element enrichments and possible chondritic Ru:Ir across the Frasnian-Famennian boundary, western New York State.

Science.gov (United States)

Over, D J; Conaway, C A; Katz, D J; Goodfellow, W D; Gregoire, D C

1997-08-01

The Frasnian-Famennian boundary is recognized as the culmination of a global mass extinction in the Late Devonian. In western New York State the boundary is a distinct horizon within a pyritic black shale bed of the upper Hanover Shale defined by the first occurrence of Palmatolepis triangularis in the absence of Frasnian conodonts. The boundary is characterized by a minor disconformity marked by a lag concentration of conodonts. Iridium at the boundary is 0.11-0.24 ng/g, two to five times background levels of <0.05 ng/g; other Ir enrichments of 0.38 ng/g and 0.49 ng/g occur within 50 cm of the conodont-constrained boundary. Numerous Ir enrichments in the boundary interval suggest extraterrestrial accretion and platinum group element (PGE) concentration at disconformities, or mobilization and concentration in organic-rich/pyritic-rich laminations from cosmic or terrestrial sources. PGE ratios of Pt/Pd and Ku/Ir at the boundary horizon approximate chondritic ratios and are suggestive of an unaltered extraterrestrial source. These values do not conclusively establish a single extraterrestrial impact as the ultimate cause of the Frasnian-Famennian mass extinction, especially given the presence of similar Ir enrichments elsewhere in the section and the absence at the boundary of microtektites and shocked mineral grains.

Magmatic ore deposits in layered intrusions - Descriptive model for reef-type PGE and contact-type Cu-Ni-PGE deposits

Science.gov (United States)

Zientek, Michael L.

2012-01-01

Layered, ultramafic to mafic intrusions are uncommon in the geologic record, but host magmatic ore deposits containing most of the world's economic concentrations of platinum-group elements (PGE) (figs. 1 and 2). These deposits are mined primarily for their platinum, palladium, and rhodium contents (table 1). Magmatic ore deposits are derived from accumulations of crystals of metallic oxides, or immiscible sulfide, or oxide liquids that formed during the cooling and crystallization of magma, typically with mafic to ultramafic compositions. "PGE reefs" are stratabound PGE-enriched lode mineralization in mafic to ultramafic layered intrusions. The term "reef" is derived from Australian and South African literature for this style of mineralization and used to refer to (1) the rock layer that is mineralized and has distinctive texture or mineralogy (Naldrett, 2004), or (2) the PGE-enriched sulfide mineralization that occurs within the rock layer. For example, Viljoen (1999) broadly defined the Merensky Reef as "a mineralized zone within or closely associated with an unconformity surface in the ultramafic cumulate at the base of the Merensky Cyclic Unit." In this report, we will use the term PGE reef to refer to the PGE-enriched mineralization, not the host rock layer. Within a layered igneous intrusion, reef-type mineralization is laterally persistent along strike, extending for the length of the intrusion, typically tens to hundreds of kilometers. However, the mineralized interval is thin, generally centimeters to meters thick, relative to the stratigraphic thickness of layers in an intrusion that vary from hundreds to thousands of meters. PGE-enriched sulfide mineralization is also found near the contacts or margins of layered mafic to ultramafic intrusions (Iljina and Lee, 2005). This contact-type mineralization consists of disseminated to massive concentrations of iron-copper-nickel-PGE-enriched sulfide mineral concentrations in zones that can be tens to hundreds

Biological role in the transformation of platinum-group mineral grains

Science.gov (United States)

Reith, Frank; Zammit, Carla M.; Shar, Sahar S.; Etschmann, Barbara; Bottrill, Ralph; Southam, Gordon; Ta, Christine; Kilburn, Matthew; Oberthür, Thomas; Ball, Andrew S.; Brugger, Joël

2016-04-01

Platinum-group elements are strategically important metals. Finding new deposits is becoming increasingly difficult owing to our limited understanding of the processes that affect their mobility in surface environments. Microorganisms have been shown to promote the mobility of metals around ore deposits. Here we show that microorganisms influence the mobility of platinum-group elements in mineral grains collected from Brazil, Australia and Colombia. Scanning electron microscopy showed biofilms covering the platinum-group mineral grains. The biofilms contained abundant platinum-group element nanoparticles and microcrystalline aggregates, and were dominated by Proteobacteria, many of which were closely related to known metal-resistant species. Some platinum-group mineral grains contained carbon, nitrogen, sulfur, selenium and iodine, suggesting the grains may be biogenic in origin. Molecular analyses show that Brazilian platinum-palladium grains hosted specific bacterial communities, which were different in composition from communities associated with gold grains, or communities in surrounding soils and sediments. Nano-phase metallic platinum accumulated when a metallophillic bacterium was incubated with a percolating platinum-containing medium, suggesting that biofilms can cause the precipitation of mobile platinum complexes. We conclude that biofilms are capable of forming or transforming platinum-group mineral grains, and may play an important role for platinum-group element dispersion and re-concentration in surface environments.

Determination of platinum-group elements in the geological standard reference materials by isotope dilution-ICPMS

Energy Technology Data Exchange (ETDEWEB)

Mingyue, Hu; Hongliao, He [National Research Center for Geoanalysis, Beijing (China)

2005-10-15

Platinum group elements (PGEs) includes platinum, palladium, iridium, osmium, rhodium and ruthenium. It has very high economic and scientific value in the field of geoscience and environmental science. But the analysis data referred by the different lab are very disperse because of the difficulty of the determination of PGEs. It makes very difficult to fix the value of the PGEs in the standard reference materials. In the article, the values of the PGEs in the standard reference materials of ocean sediment are determined by isotope dilution technique and dependable values of these elements are provided. (authors)

Determination of platinum-group elements in the geological standard reference materials by isotope dilution-ICPMS

International Nuclear Information System (INIS)

Hu Mingyue; He Hongliao

2005-01-01

Platinum group elements (PGEs) includes platinum, palladium, iridium, osmium, rhodium and ruthenium. It has very high economic and scientific value in the field of geoscience and environmental science. But the analysis data referred by the different lab are very disperse because of the difficulty of the determination of PGEs. It makes very difficult to fix the value of the PGEs in the standard reference materials. In the article, the values of the PGEs in the standard reference materials of ocean sediment are determined by isotope dilution technique and dependable values of these elements are provided. (authors)

Platinum-group elements in southern Africa: mineral inventory and an assessment of undiscovered mineral resources: Chapter Q in Global mineral resource assessment

Science.gov (United States)

Zientek, Michael L.; Causey, J. Douglas; Parks, Heather L.; Miller, Robert J.

2014-01-01

The platinum-group elements, platinum, palladium, rhodium, ruthenium, iridium, and osmium, possess unique physical and chemical characteristics that make them indispensable to modern technology and industry. However, mineral deposits that are the main sources of these elements occur only in three countries in the world, raising concerns about potential disruption in mineral supply. Using information in the public domain, mineral resource and reserve information has been compiled for mafic and ultramafic rocks in South Africa and Zimbabwe that host most of the world’s platinum-group element resources.

Determination of platinum group elements and gold in reference materials by instrumental neutron activation analysis and inductively coupled plasma-mass spectrometry with nickel sulphide fire-assay collection

International Nuclear Information System (INIS)

Morcelli, C.P.R.; Figueiredo, A.M.G.; Sarkis, J.E.S.; Kakazu, M.; Enzweiler, J.

2002-01-01

Instrumental Neutron Activation Analysis (INAA) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) after NiS fire assay were used to determine platinum group elements (PGE) and Au in the geological reference materials peridotite GPt-3 and pyroxene peridotite GPt-4 (IGGE, China). INAA has been one of the most useful analytical techniques for PGEs and Au determination, due to its high sensitivity and accuracy. After the fire assay, the NiS button is dissolved in concentrated hydrochloric acid, leaving a residue of insoluble PGE sulphides; the solution is filtered and the filter is directly irradiated with neutrons. In more recent years, ICP-MS with nickel fire assay collection and tellurium coprecipitation has been used as a mean of analysing PGE, with the main advantage of avoiding problems of losses of PGE during the HCl digestion of the NiS button. Buttons were prepared by mixing the sample (10-15 g) with fluxes, nickel and sulphur in a fire clay crucible and fused at temperatures around 1000 deg C. For NAA, the filters containing the PGEs and Au were irradiated at the IEA-R1 research nuclear reactor at IPEN. The measurements of the induced gamma-ray activity were carried out in an hyperpure Ge detector. In general, the results obtained by the two techniques were in good agreement with recommended values. INAA results exhibited higher values than the recommended values for Pd and Pt in GPt-3, while the opposite effect was observed for GPt-4 sample. Ru was not detected by INAA. On the other hand, Rh and Ir were determined more accurately by INAA (relative errors better than 10%). The ICP-MS analytical technique showed better detection limits, and all the PGE were determined. Results obtained for Pt and Pd presented accuracy better than 5% while losses were observed for Os and Ir. (author)

Simultaneous determination of platinum group elements and rhenium in rock samples using isotope dilution inductively coupled plasma mass spectrometry after cation exchange separation followed by solvent extraction

International Nuclear Information System (INIS)

Shinotsuka, Kazunori; Suzuki, Katsuhiko

2007-01-01

A simple and precise determination method for platinum group elements (PGEs) and Re in rock samples was developed using isotope dilution coupled with inductively coupled plasma mass spectrometry (ID-ICP-MS). Cation exchange separation was employed for simplicity, because it is applicable to group separation and simultaneous isotopic measurement in contrast with the widely used anion exchange separation which entails separate elution. However, its application to ID-ICP-MS has been limited due to spectral interferences from impurities retained in the PGE fraction even after ion chromatography. To overcome this limitation, solvent extraction using N-benzoyl-N-phenylhydroxylamine (BPHA) in chloroform was successfully applied for further purification. After the examination of optimum experimental parameters in cation exchange separation and solvent extraction using synthetic PGE solution, the established procedure was applied to the determination of PGEs and Re in some geochemical reference materials. The obtained results agreed well with the literature data determined using the different digestion methods (NiS fire assay and the use of a high-pressure asher) within the analytical uncertainties of each other. Significant difference in reproducibility between Ru, Ir, Pt and Os group, and Pd and Re group was observed in the results for BHVO-2 and JA-2. By considering the error factors affecting analytical reproducibility, we concluded that the difference is ascribed to the sample heterogeneity of minor minerals enriched in Ru, Ir, Pt and Os

Komatiites and nickel sulfide ores of the Black Swan area, Yilgarn Craton, Western Australia. 4. Platinum group element distribution in the ores, and genetic implications

Science.gov (United States)

Barnes, Stephen J.

2004-11-01

The Black Swan komatiite sequence, in the Eastern Goldfields province of the Archaean Yilgarn Craton in Western Australia, is a body of dominantly olivine-rich cumulates with lesser volumes of spinifex textured rocks, interpreted as a section through an extensive komatiite lava flow field. The sequence hosts a number of nickel sulfide orebodies, including the Silver Swan massive shoot and the Cygnet and Black Swan disseminated orebodies. The massive sulfide orebodies of the Black Swan Succession are pervasively depleted in all platinum group elements (PGEs), particularly Pt and Pd, despite very high Ni contents. This depletion cannot be explained by R-factor variations, which would also require relatively low Ni tenors. The PGE depletion could be explained in part if the ores are enriched in a monosulfide solid solution (MSS) cumulate component, but requires some additional fractional segregation of sulfide melt upstream from the site of deposition. The Silver Swan orebody shows a remarkably consistent vertical zonation in PGE contents, particularly in Ir, Ru, Rh, Os, which increase systematically from very low levels at the stratigraphic base of the sulfide body to maxima corresponding roughly with the top of a lower layer of the orebody rich in silicate inclusions. Platinum shows the opposite trend, but is somewhat modified by remobilisation during talc carbonate alteration. A similar pattern is also observed in the adjacent White Swan orebody. This zonation is interpreted and modelled as the result of fractional crystallisation of MSS from the molten sulfide pool. The strong IPGE depletion towards the base of the orebody may be a consequence of sulfide liquid crystallisation in an inverted thermal gradient, between a thin rapidly cooling upper rind of komatiite lava and a hot substrate.

PGE Production in Southern Africa, Part II: Environmental Aspects

Directory of Open Access Journals (Sweden)

Benedikt Buchspies

2017-11-01

Full Text Available Platinum group elements (PGEs, 6E PGE = Pt + Pd + Rh + Ru + Ir + Au are used in numerous applications that seek to reduce environmental impacts of mobility and energy generation. Consequently, the future demand for PGEs is predicted to increase. Previous studies indicate that environmental impacts of PGE production change over time emphasizing the need of up-to-date data and assessments. In this context, an analysis of environmental aspects of PGE production is needed to support the environmental assessment of technologies using PGEs, to reveal environmental hotspots within the production chain and to identify optimization potential. Therefore, this paper assesses greenhouse gas (GHG emissions, cumulative fossil energy demand (CEDfossil, sulfur dioxide (SO2 emissions and water use of primary PGE production in Southern Africa, where most of today’s supply originates from. The analysis shows that in 2015, emissions amounted to 45 t CO2-eq. and 502 kg SO2 per kg 6E PGE in the case GHG and SO2 emissions, respectively. GHG emissions are dominated by emissions from electricity provision contributing more than 90% to the overall GHG emissions. The CEDfossil amounted to 0.60 TJ per kg 6E PGE. A detailed analysis of the CEDfossil reveals that electricity provision based on coal power consumes the most fossil energy carriers among all energy forms. Results show that the emissions are directly related to the electricity demand. Thus, the reduction in the electricity demand presents the major lever to reduce the consumption of fossil energy resources and the emission of GHGs and SO2. In 2015, the water withdrawal amounted to 0.272 million L per kg 6E PGE. Additionally, 0.402 million L of recycled water were used per kg 6E PGE. All assessed indicators except ore grades and production volumes reveal increasing trends in the period from 2010 to 2015. It can be concluded that difficult market conditions (see part I of this paper series and increasing

Development of an ultratrace analysis method for elements of the platinum group contained in environmental and geological samples using an ICP-QMS with isotope dilution analysis and suitable separation techniques; Entwicklung eines Verfahrens zur Ultraspurenbestimmung der Platingruppenelemente in Umwelt- und geologischen Proben mit einem ICP-QMS unter Verwendung der Isotopenverduennungsanalyse sowie geeigneter Separationstechniken

Energy Technology Data Exchange (ETDEWEB)

Mueller, M.

2001-07-01

environment of elements of the platinum group. [German] Schwerpunkt dieser Arbeit war die Verfahrensentwicklung zur Ultraspurenbestimmung der PGE in Umwelt- und geologischen Proben unter Verwendung der massenspektrometrischen Isotopenverduennungsanalyse mit anschliessender Bestimmung an einem Quadrupol ICP-MS (ICP-QMSIVA). Das in dieser Arbeit entwickelte Verfahren zur Ultraspurenbestimmung der PGE mit ICPQMSIVA wurde im Rahmen des Projektes ''Production and certification of a road dust reference material for platinum, palladium and rhodium (PGEs) in automative catalytic converters (PACEPAC)'' der Europaeischen Union zur Zertifizierung von zwei Referenzmaterialien fuer Umweltproben eingesetzt. Hierbei wurde in der Vorrunde der Zertifizierung (''intercomparison round'') eine sehr gute Uebereinstimmung der Ergebnisse mit dem gewichteten Mittelwert der Ergebnisse fuer Pd und Pt mit den uebrigen teilnehmenden Laboratorien festgestellt. Die mit der hier entwickelten Methode erhaltenen Ergebnisse wurden ohne Ausnahme fuer alle gemessenen Elemente zur vorlaeufigen Zertifizierung herangezogen. Damit leistete die vorliegende Arbeit einen erheblichen Beitrag zum erfolgreichen Abschluss dieses Projekts. Den Erwartungen hinsichtlich Richtigkeit und Reproduzierbarkeit des entwickelten Verfahrens wurde somit voll entsprochen. Erneut konnte die grosse Bedeutung der Isotopenverduennungstechnik fuer die Zertifizierung von Referenzmaterialien aufgezeigt werden, da mit dieser Technik bei sachgerechtem Einsatz Ergebnisse hoher Richtigkeit erzielt werden. Durch vergleichende Messungen mit der NiS-Dokimasie und NAA, die in einer Kooperation mit dem Kernchemischen Institut der Universitaet Mainz durchgefuehrt wurden, und dem hier verwendeten Verfahren, konnten uebereinstimmende Daten, hinsichtlich der Abnahme der Konzentrationen von Pd und Pt in Abhaengigkeit von der Entfernung zu einer Autobahn, erzielt werden. Diese Arbeit und die Forschungsergebnisse, die

Palladium, platinum, rhodium, iridium and ruthenium in chromite- rich rocks from the Samail ophiolite, Oman.

Science.gov (United States)

Page, N.J.; Pallister, J.S.; Brown, M.A.; Smewing, J.D.; Haffty, J.

1982-01-01

30 samples of chromitite and chromite-rich rocks from two stratigraphic sections, 250 km apart, through the basal ultramafic member of the Samail ophiolite were spectrographically analysed for platinum-group elements (PGE) and for Co, Cu, Ni and V. These data are reported as are Cr/(Cr + Al), Mg/(Mg + Fe) and wt.% TiO2 for most samples. The chromitite occurs as pods or lenses in rocks of mantle origin or as discontinuous layers at the base of the overlying cumulus sequence. PGE abundances in both sections are similar, with average contents in chromite-rich rocks: Pd 8 ppb, Pt 14 ppb, Rh 6 ppb, Ir 48 ppb and Ru 135 ppb. The PGE data, combined with major-element and petrographic data on the chromitite, suggest: 1) relatively larger Ir and Ru contents and highest total PGE in the middle part of each section; 2) PGE concentrations and ratios do not correlate with coexisting silicate and chromite abundances or chromite compositions; 3) Pd/PGE, on average, increases upward in each section; 4) Samail PGE concentrations, particularly Rh, Pt and Pd, are lower than the average values for chromite-rich rocks in stratiform intrusions. 2) suggests that PGEs occur in discrete alloy or sulphide phases rather than in the major oxides or silicates, and 4) suggests that chromite-rich rocks from the oceanic upper mantle are depleted in PGE with respect to chondrites. L.C.C.

Charged particle induced delayed X-rays (DEX) for the analysis of intermediate and heavy elements

Science.gov (United States)

Pillay, A. E.; Erasmus, C. S.; Andeweg, A. H.; Sellschop, J. P. F.; Annegarn, H. J.; Dunn, J.

1988-12-01

The emission of K X-rays from proton-rich and metastable radionuclides, following proton activation of the stable isotopes of the elements of interest, has not been widely used as a means of analysis. The thrust of this paper proposes a nuclear technique using delayed X-rays for the analysis of low concentrations of intermediate and heavy elements. The method is similar to the delayed gamma-ray technique. Proton bombardment induces mainly (p, n) reactions whereas the delayed X-rays originate largely from e --capture and isomeric transition. Samples of rare earth and platinum group elements (PGE), in the form of compacted powders, were irradiated with an 11 MeV proton beam and delayed X-rays detected with a 100 mm 2 Ge detector. Single element spectra for a range of rare earths and PGEs are presented. Analytical conditions are demonstrated for Pd in the range 0.1-5%. Spectra from actual geological samples of a PGE ore, preconcentrated by fire-assay, and monazite are presented. All six platinum group elements are visible and interference-free in a single spectrum, a marked advance on other nuclear techniques for these elements, including PIXE and neutron activation analysis (NAA).

Platinum-group metals from nuclear reactions as a possible resource

International Nuclear Information System (INIS)

Jensen, G.A.

1985-03-01

Spent nuclear fuels contain significant quantities of three of the platinum-group metals (ruthenium, rhodium, and palladium), and a related element technetium, which is nearly absent in nature. Applications for ruthenium, rhodium, and palladium are well established. Since the supply of these and other platinum metals is largely from foreign sources, they are considered strategic materials. Existing and future spent nuclear fuels contain quantities of these platinum metals that exceed the United States reserve base. Technetium has properties similar to platinum metals and has unique, useful properties of its own. The technical feasibility of recovering and using fission product platinum metals (and technetium) extensively in industry depends on: thoroughly decontaminating platinum-group metals from all other radioactive materials in the waste stream; separating platinum-group metals from one another in very high purity; using applications where appropriate control of the residual radioactivity is possible; and whether or not the United States will recover or process spent fuel prior to repository storage. If the radioactivity must be removed, isotope separation or long term storage to allow decay of the contained radioisotopes may be possible. 7 figs., 7 tabs

Platinum-Group Elements in Soils and Street Dust of the Southeastern Administrative District of Moscow

Science.gov (United States)

Ladonin, D. V.

2018-03-01

The contents of five platinum-group metals (Ru, Rh, Pd, Ir, and Pt) in soils and street dust of the Southeastern administrative district (SEAD) of Moscow have been determined. The contents of these elements in soils may considerably exceed their natural abundances in the lithosphere and are characterized by considerable variability and asymmetric frequency distribution. A close correlation between Rh, Pd, and Pt contents in soils and street dust has been shown. The data on the contents of the elements and the ratios between them suggest that motor vehicles are the major source of pollution of soils and street dust in the studied district.

Neodymium and strontium isotopic stratigraphy of the neo-archean Rio Jacare Sill-Bahia, Brazil and its relation to PGE mineralization

International Nuclear Information System (INIS)

Brito, Reinaldo S.C de; Pimentel, Marcio M.; Nilson, Ariplinio A.; Gioia, Simone M

2001-01-01

Platinum-Group Elements (PGE) deposition in magma chambers is generally accepted as being triggered by sulphur immiscibility via sulfidasation and/or felsification of magmas. These processes can be related to fractional crystallization, and mixing of batches of magmas, crustal contamination or by the combination of these process. Important isotopic studies have been carried out by many authors such as Lambert (1989) and Marcantonio (1995) in the Stillwater Complex, Kruger and Marsh (1989) and Cawthorn (1996) in the Bushveld Complex. Those works set out to understand the role of isotopic changes in the genesis of PGE deposits from JM and Merensky Reefs, respectively. They attributed those PGE mineralizations to isotopically constrained mixing/contamination episodes associated to subtle changes in steady vertical fractionation trends. This work presents stratigraphycally-plotted Nd and Sr isotopic data together with evidence of mineral and whole rock geochemistry disturbance in smooth fractionations trends of the Rio Jacare Sill. Data interpretation suggest the sill was formed via fractional crystallisation and mixing of at least three magma batches, combined with some degree of host rocks assimilation. Isotopic changes were also related to PGE anomalies associated with transitional facies formed during such mixing episodes (au)

PALLADIUM, PLATINUM, RHODIUM, RUTHENIUM AND IRIDIUM IN PERIDOTITES AND CHROMITITES FROM OPHIOLITE COMPLEXES IN NEWFOUNDLAND.

Science.gov (United States)

Page, Norman J; Talkington, Raymond W.

1984-01-01

Samples of spinel lherzolite, harzburgite, dunite, and chromitite from the Bay of Islands, Lewis Hills, Table Mountain, Advocate, North Arm Mountain, White Hills Periodite Point Rousse, Great Bend and Betts Cove ophiolite complexes in Newfoundland were analyzed for the platinum-group elements (PGE) Pd, Pt, Rh, Ru and Ir. The ranges of concentration (in ppb) observed for all rocks are: less than 0. 5 to 77 (Pd), less than 1 to 120 (Pt), less than 0. 5 to 20 (Rh), less than 100 to 250 (Ru) and less than 20 to 83 (Ir). Chondrite-normalized PGE ratios suggest differences between rock types and between complexes. Samples of chromitite and dunite show relative enrichment in Ru and Ir and relative depletion in Pt and Pd.

Direct determination of platinum group elements and their distributions in geological and environmental samples at the ng g(-1) level using LA-ICP-IDMS.

Science.gov (United States)

Boulyga, Sergei F; Heumann, Klaus G

2005-10-01

Laser ablation inductively coupled plasma isotope dilution mass spectrometry (LA-ICP-IDMS) was applied to the direct and simultaneous determination of the platinum group elements (PGEs) Pt, Pd, Ru, and Ir in geological and environmental samples. A special laser ablation system with high ablation rates was used, along with sector field ICP-MS. Special attention was paid to deriving the distributions of PGEs in the pulverized samples. IDMS could not be applied to the (mono-isotopic) Rh, but the similar ablation behavior of Ru and Rh allowed Rh to be simultaneously determined via relative sensitivity coefficients. The laser ablation process produces hardly any oxide ions (which usually cause interference in PGE analysis with liquid sample injection), so the ICP-MS can be run in its low mass resolution but high-sensitivity mode. The detection limits obtained for the geological samples were 0.16 ng g(-1), 0.14 ng g(-1), 0.08 ng g(-1), 0.01 ng g(-1) and 0.06 ng g(-1) for Ru, Rh, Pd, Ir and Pt, respectively. LA-ICP-IDMS was applied to different geological reference materials (TDB-1, WGB-1, UMT-1, WMG-1, SARM-7) and the road dust reference material BCR-723, which are only certified for some of the PGEs. Comparisons with certified values as well as with indicative values from the literature demonstrated the validity of the LA-ICP-IDMS method. The PGE concentrations in subsamples of the road dust reference material correspond to a normal distribution, whereas the distributions in the geological reference materials TDB-1, WGB-1, UMT-1, WMG-1, and SARM-7 are more complex. For example, in the case of Ru, a logarithmic normal distribution best fits the analyzed concentrations in TDB-1 subsamples, whereas a pronounced nugget effect was found for Pt in most geological samples.

Concentrations of Platinum Group Elements (Pt, Pd, Rh in Airborne Particulate Matter (PM2.5 and PM10-2.5 Collected at Selected Canadian Urban Sites: a Case Study

Directory of Open Access Journals (Sweden)

Celo V.

2013-04-01

Full Text Available Increasing environmental concentrations of platinum group elements (PGEs, in particular platinum (Pt, palladium (Pd and rhodium (Rh, from catalytic converters has been reported worldwide. Initially it was believed that the emitted PGEs remain in the roadside environment, but recent studies have shown that fine PGE-containing particles can be transported and distributed at regional and long-range levels. Therefore, the monitoring of PGEs in airborne particulate matter (PM is important for the estimation of potential risks to human health and to the ecosystem. The aim of this study is to present the first results from an analysis on the concentration and distribution of Pt, Pd and Rh in PM collected on Teflon filters at two selected urban sites (Toronto, Ontario; Edmonton, Alberta collected within the Canadian National Air Pollution Surveillance (NAPS network. In this work, a quadruple inductively coupled plasma mass spectrometry (ICP-MS, combined with microwave assisted acid digestion using aqua regia was used. A cation exchange separation was used to alleviate the matrix-induced spectral and nonspectral interferences prior to ICP-MS analysis. To obtain sufficient material needed for PGEs analysis, fine PM (particles with aerodynamic diameter less than 2.5 mm; PM2.5 and coarse PM (with aerodynamic diameter between 2.5 and 10 mm; PM10-2.5 samples were combined into composite samples on a seasonal basis. The obtained results will be discussed and compared with literature data.

Mafic and ultramafic rocks, and platinum mineralisation potential, in the Longwood Range, Southland, New Zealand

International Nuclear Information System (INIS)

Ashley, P.; Craw, D.; Mackenzie, D.; Rombouts, M.; Reay, A.

2012-01-01

Intrusive rocks in the Longwood Range represent a component of the Permian Brook Street Terrane. They include diffusely layered, cumulate-textured olivine gabbro, troctolite, and gabbro, and gradations into non-cumulate gabbro and gabbronorite. Volumetrically small ultramafic layers occur (plagioclase wehrlite), and thin veins of felsic rocks ranging from quartz diorite to trondhjemite. Primary olivine, plagioclase, clinopyroxene, and subordinate orthopyroxene and hornblende are commonly altered or metamorphosed to amphiboles, minor spinel, magnetite, chlorite, biotite and clinozoisite, and serpentine in olivine-rich rocks. Accessory primary Ti-bearing magnetite and ilmenite occur, and trace Cr-magnetite is characteristic of olivine-rich rocks. Trace pyrrhotite, chalcopyrite, pentlandite, and pyrite could reflect equilibrated late magmatic, and alteration-derived phases. Key petrochemical characteristics of the rock suite are high Mg, Al, Ca, and Sr contents, and low alkali, LILE, and sulfur contents. Platinum and Pd are locally enriched in drill-hole intercepts, but zones appear unrelated to rock type, magnetic properties, or to S, Cu, Ni, Cr, or Au values. Local platinum group element (PGE) enrichment in altered rocks implies metamorphic and/or hydrothermal redistribution. Pervasive PGE enrichment in Longwood rocks is an indicator of potential 'fertility', but evidence is currently lacking for the precipitation of primary stratiform PGE accumulations from a sulfide liquid saturated magma. (author). 41 refs., 11 figs., 2 tabs.

Direct determination of platinum group elements and their distributions in geological and environmental samples at the ng g{sup -1} level using LA-ICP-IDMS

Energy Technology Data Exchange (ETDEWEB)

Boulyga, Sergei F.; Heumann, Klaus G. [Johannes Gutenberg-University Mainz, Institute of Inorganic Chemistry and Analytical Chemistry, Mainz (Germany)

2005-10-01

Laser ablation inductively coupled plasma isotope dilution mass spectrometry (LA-ICP-IDMS) was applied to the direct and simultaneous determination of the platinum group elements (PGEs) Pt, Pd, Ru, and Ir in geological and environmental samples. A special laser ablation system with high ablation rates was used, along with sector field ICP-MS. Special attention was paid to deriving the distributions of PGEs in the pulverized samples. IDMS could not be applied to the (mono-isotopic) Rh, but the similar ablation behavior of Ru and Rh allowed Rh to be simultaneously determined via relative sensitivity coefficients. The laser ablation process produces hardly any oxide ions (which usually cause interference in PGE analysis with liquid sample injection), so the ICP-MS can be run in its low mass resolution but high-sensitivity mode. The detection limits obtained for the geological samples were 0.16 ng g{sup -1}, 0.14 ng g{sup -1}, 0.08 ng g{sup -1}, 0.01 ng g{sup -1} and 0.06 ng g{sup -1} for Ru, Rh, Pd, Ir and Pt, respectively. LA-ICP-IDMS was applied to different geological reference materials (TDB-1, WGB-1, UMT-1, WMG-1, SARM-7) and the road dust reference material BCR-723, which are only certified for some of the PGEs. Comparisons with certified values as well as with indicative values from the literature demonstrated the validity of the LA-ICP-IDMS method. The PGE concentrations in subsamples of the road dust reference material correspond to a normal distribution, whereas the distributions in the geological reference materials TDB-1, WGB-1, UMT-1, WMG-1, and SARM-7 are more complex. For example, in the case of Ru, a logarithmic normal distribution best fits the analyzed concentrations in TDB-1 subsamples, whereas a pronounced nugget effect was found for Pt in most geological samples. (orig.)

Levels of platinum group elements and rare-earth elements in wild mushroom species growing in Poland.

Science.gov (United States)

Mleczek, Mirosław; Niedzielski, Przemysław; Kalač, Pavel; Siwulski, Marek; Rzymski, Piotr; Gąsecka, Monika

2016-01-01

Due to limited data-describing abilities of mushrooms to accumulate platinum group elements (PGEs) and rare-earth elements (REEs), the aim of this study was to determine, by inductively coupled plasma optical emission spectrometry followed by microwave-assisted sample digestion by nitric acid, the content of these elements in 20 mushroom species (10 above ground and 10 growing on wood), mostly edible, collected near a busy trunk road. The highest content of PGEs in above-ground mushroom species was observed in Lepista gilva and Suillus bovinus fruit bodies (0.38 ± 0.05 and 0.37 ± 0.03 mg kg(-1) DW, respectively), while in mushrooms growing on wood, the highest content was observed in Pleurotus ostreatus (0.35 ± 0.04 mg kg(-1) DW). The mean content of PGEs for both these groups was 0.23 ± 0.08 and 0.26 ± 0.07 mg kg(-1) DW, respectively. The highest content of REEs in Suillus luteus and Tricholoma equestra was 5.03 ± 0.50 and 2.18 ± 0.56 mg kg(-1) DW, respectively, but within mushrooms growing on wood in Ganoderma applanatum fruiting bodies it was 4.19 ± 0.78 mg kg(-1) DW. Mean contents of REEs were 1.39 ± 1.21 and 1.61 ± 0.97 mg kg(-1) DW in above-ground species and species growing on wood, respectively. Generally, the group of mushroom species growing on wood was capable of slightly higher accumulation of both REEs and PGEs. No limits have been established for both the groups until now.

Multi-elemental characterization of tunnel and road dusts in Houston, Texas using dynamic reaction cell-quadrupole-inductively coupled plasma–mass spectrometry: Evidence for the release of platinum group and anthropogenic metals from motor vehicles

International Nuclear Information System (INIS)

Spada, Nicholas; Bozlaker, Ayse; Chellam, Shankararaman

2012-01-01

Highlights: ► Analytical method for PGEs, main group, transition and rare earth metals developed. ► Comprehensive characterization of road and tunnel dust samples was accomplished. ► PGEs in dusts arise from autocatalyst attrition. ► Mobile sources also contributed to Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, W and Pb. ► All other elements, including rare earths arose from crustal sources. - Abstract: Platinum group elements (PGEs) including Rh, Pd, and Pt are important tracers for vehicular emissions, though their measurement is often challenging and difficult to replicate in environmental campaigns. These challenges arise from sample preparation steps required for PGE quantitation, which often cause severe isobaric interferences and spectral overlaps from polyatomic species of other anthropogenically emitted metals. Consequently, most previous road dust studies have either only quantified PGEs or included a small number of anthropogenic elements. Therefore a novel analytical method was developed to simultaneously measure PGEs, lanthanoids, transition and main group elements to comprehensively characterize the elemental composition of urban road and tunnel dusts. Dust samples collected from the vicinity of high-traffic roadways and a busy underwater tunnel restricted to single-axle (predominantly gasoline-driven) vehicles in Houston, TX were analyzed for 45 metals with the newly developed method using dynamic reaction cell-quadrupole-inductively coupled plasma–mass spectrometry (DRC-q-ICP–MS). Average Rh, Pd and Pt concentrations were 152 ± 52, 770 ± 208 and 529 ± 130 ng g −1 respectively in tunnel dusts while they varied between 6 and 8 ng g −1 , 10 and 88 ng g −1 and 35 and 131 ng g −1 in surface road dusts. Elemental ratios and enrichment factors demonstrated that PGEs in dusts originated from autocatalyst attrition/abrasion. Strong evidence is also presented for mobile source emissions of Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, W and Pb. However

Recycling of platinum group metals from the automotive catalysts

International Nuclear Information System (INIS)

Benevit, Mariana; Petter, Patricia Melo Halmenschlager; Veit, Hugo Marcelo

2014-01-01

Currently it is very important to use alternative sources of raw material for obtaining metals, avoiding the traditional mining. This work aims to characterize and evaluate the recoverability of platinum group metals present in automotive catalysts. Thus, the catalysts were divided into two groups: the first was catalysts used in 1.0 cars and the second was catalyst used in 2.0 cars. DRX and FRX techniques and chemical analysis performed by ICP/OES was used to characterized these materials. The results showed that there is a significant amount of platinum group elements in catalyst waste, which can be separated and reused. In the next step, hydro and pyrometallurgical routes, for metals extraction from catalyst waste, will be studied. (author)

Platinum group elements and gold in ferromanganese crusts from ...

Indian Academy of Sciences (India)

The strong enrichment of Pt (up to 1 ppm) relative to the other PGE and its pos- itive correlations with ... around Late Miocene as indicated by the contin- uous growth of ...... 198. 331–351. Koschinsky A and Halbach P 1995 Sequential leaching.

Segregation of the elements of the platinum group in a simulated high-level waste glass

International Nuclear Information System (INIS)

Mitamura, H.; Banba, T.; Kamizono, H.; Kiriyama, Y.; Kumata, M.; Murakami, T.; Tashiro, S.

1983-01-01

Segregation of the elements of the platinum group occurred during vitrification of the borosilicate glass containing 20 wt% simulated high-level waste oxides. The segregated materials were composed of two crystalline phases: one was the solid solution of ruthenium and rhodium dioxides and the other was that of palladium and rhodium metals also with tellurium. The segregated materials were not distributed homogeneously throughout the glass: (i) on the surface of the glass, there occurred palladium, rhodium and tellurium alloy alone; and (ii) at the inner part of the glass, the agglomerates of the two phases were concentrated in one part and dispersed in the other

Spatial and temporal distribution of platinum, palladium and rhodium in Zagreb air.

Science.gov (United States)

Rinkovec, Jasmina; Pehnec, Gordana; Godec, Ranka; Davila, Silvije; Bešlić, Ivan

2018-09-15

Platinum (Pt), palladium (Pd) and rhodium (Rh) are most widely used in the production of automotive catalytic converters that serve to reduce toxic emissions from motor vehicles. The aim of this study was to quantitatively determine the levels of platinum, palladium and rhodium in the PM 10 and PM 2.5 fraction of airborne particle matter and find their spatial and temporal distribution at different polluted areas of the city of Zagreb, Croatia. The method used in this paper included weekly sampling of airborne particle matter on quartz filters, microwave digestion in acid under high pressure and temperature, and analysis by inductively coupled plasma mass spectrometry (ICP MS). The results have shown that the highest mean values at all three sampling stations (North, Center, South) were obtained for palladium (3.856 pg m -3 , 5.396 pg m -3 , 5.600 pg m -3 ) and the lowest for rhodium (0.444 pg m -3 , 0.643 pg m -3 , 0.750 pg m -3 ). The average mass concentrations of platinum group elements (PGE) in PM 10 increased for all three elements in the direction North Zagreb are the first results of their kind for this area and will provide insights into the contribution of catalytic converters to the presence of these elements in the environment. Copyright © 2018 Elsevier B.V. All rights reserved.

Anthrobiogeochemical platinum, palladium and rhodium cycles of earth: Emerging environmental contamination

Science.gov (United States)

Mitra, Arijeet; Sen, Indra Sekhar

2017-11-01

Anthrobiogeochemical cycles have been a subject of scientific research for many decades as they are important for identifying possible sources, sinks, and pathways of an element in the environment. In this study, we quantified global cycles for the platinum group elements (PGE; platinum (Pt), palladium (Pd) and rhodium (Rh)). We quantified the stocks of Pt, Pd, and Rh in Earth's various reservoirs, such as the core, mantle, consolidated crust, biomass, seawater, unconsolidated sediments, and atmosphere, as well as coal and petroleum deposits. We further quantified their fluxes, both natural and anthropogenic, between each reservoir, by identifying the flows across the hydrosphere, geosphere, biosphere, atmosphere and anthroposphere, including from mining activities, fossil fuel and biomass burning, construction activities, soil erosion, human contributions to net primary productivity, riverine transport, aeolian dust movement, primary production, volcanic eruption, sea-salt spray, crustal subduction, crust formation at mid ocean ridges, PGE recovery from recycling processes, and cosmic dust inputs at the Earth's surface. Stocks of PGEs were quantified by multiplying the mass of the reservoir by the average Pt, Pd and Rh concentration in the reservoir, whereas Pt, Pd and Rh fluxes were calculated by multiplying the rate of mass movement across the reservoirs with the Pt, Pd and Rh concentrations of the material. Uncertainties were explicitly incorporated in stock and flow estimations through Monte Carlo simulations. Our calculations reveal that the total surficial anthropogenic Pt, Pd, and Rh mobilizations were greater than their corresponding natural surficial mobilizations. We show that crustal subduction and crustal formation is the most important natural flow and contributes 21-42% of total PGE mobilization. When Earth's surficial processes are considered, soil erosion is the dominant flow for Rh and Pt mobilization, comprising 33% and 13%, respectively, of the

In vitro investigations of platinum, palladium, and rhodium mobility in urban airborne particulate matter (PM10, PM2.5, and PM1) using simulated lung fluids.

Science.gov (United States)

Zereini, Fathi; Wiseman, Clare L S; Püttmann, Wilhelm

2012-09-18

Environmental concentrations of platinum group elements (PGE) have been increasing since the introduction of automotive catalytic converters to control harmful emissions. Assessments of the human health risks of exposures to these elements, especially through the inhalation of PGE-associated airborne particulate matter (PM), have been hampered by a lack of data on their bioaccessibility. The purpose of this study is to apply in vitro methods using simulated human lung fluids [artificial lysosomal fluid (ALF) and Gamble's solution] to assess the mobility of the PGE, platinum (Pt), palladium (Pd), and rhodium (Rh) in airborne PM of human health concern. Airborne PM samples (PM(10), PM(2.5), and PM(1)) were collected in Frankfurt am Main, Germany. For comparison, the same extraction experiments were conducted using the standard reference material, Used Auto Catalyst (monolith) (NIST 2557). Pt and Pd concentrations were measured using isotope dilution ICP-Q-MS, while Rh was measured directly with ICP-Q-MS (in collision mode with He), following established matrix separation and enrichment procedures, for both solid (filtered residues) and extracted sample phases. The mobilized fractions measured for PGE in PM(10), PM(2.5), and PM(1) were highly variable, which can be attributed to the heterogenic nature of airborne PM and its composition. Overall, the mobility of PGE in airborne PM samples was notable, with a mean of 51% Rh, 22% Pt, and 29% Pd present in PM(1) being mobilized by ALF after 24 h. For PM(1) exposed to Gamble's solution, a mean of 44% Rh, 18% Pt, and 17% Pd was measured in solution after 24 h. The mobility of PGE associated with airborne PM was also determined to be much higher compared to that measured for the auto catalyst standard reference material. The results suggest that PGE emitted from automotive catalytic converters are likely to undergo chemical transformations during and/or after being emitted in the environment. This study highlights the need

Assessment of sublethal endpoints after chronic exposure of the nematode Caenorhabditis elegans to palladium, platinum and rhodium.

Science.gov (United States)

Schertzinger, Gerhard; Zimmermann, Sonja; Grabner, Daniel; Sures, Bernd

2017-11-01

The aim of this study was to investigate chronic effects of the platinum-group elements (PGE) palladium (Pd), platinum (Pt) and rhodium (Rh) on the nematode Caenorhabditis elegans. Aquatic toxicity testing was carried out according to ISO 10872 by determining 96 h EC 50 values for sublethal endpoints, including growth, fertility and reproduction. Single PGE standard solutions were used as metal source. Based on the EC 50 values for Pt, reproduction (96 h EC 50  = 497 μg/L) was the most sensitive endpoint followed by fertility (96 h EC 50  = 726 μg/L) and growth (96 h EC 50  = 808 μg/L). For Pd, no precise EC 50 values could be calculated due to bell-shaped concentration response curves, but the 96 h EC 50 for reproduction ranged between 10 and 100 μg/L. Pd and Pt had effects on all endpoints. With raising element concentrations reproduction was inhibited first. At a certain concentration, fertility was also affected, which in turn had an additional effect on reproduction. Growth inhibition can also lead to a loss of fertility if the worms do not reach an appropriate body size to become fertile. Rhodium showed no inhibition of any endpoint between concentrations of 100 to 10,000 μg Rh/L. The results of this study allow the following order of PGE with respect to decreasing toxicity to C. elegans: Pd > Pt » Rh. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fractionation of the platinum-group elments and Re during crystallization of basalt in Kilauea Iki Lava Lake, Hawaii

Science.gov (United States)

Pitcher, L.; Helz, R.T.; Walker, R.J.; Piccoli, P.

2009-01-01

Kilauea Iki lava lake formed during the 1959 summit eruption of Kilauea Volcano, then crystallized and differentiated over a period of 35??years. It offers an opportunity to evaluate the fractionation behavior of trace elements in a uniquely well-documented basaltic system. A suite of 14 core samples recovered from 1967 to 1981 has been analyzed for 5 platinum-group elements (PGE: Ir, Os, Ru, Pt, Pd), plus Re. These samples have MgO ranging from 2.4 to 26.9??wt.%, with temperatures prior to quench ranging from 1140????C to ambient (110????C). Five eruption samples were also analyzed. Osmium and Ru concentrations vary by nearly four orders of magnitude (0.0006-1.40??ppb for Os and 0.0006-2.01??ppb for Ru) and are positively correlated with MgO content. These elements behaved compatibly during crystallization, mostly likely being concentrated in trace phases (alloy or sulfide) present in olivine phenocrysts or included chromite. Iridium also correlates positively with MgO, although less strongly than Os and Ru. The somewhat poorer correlation for Ir, compared with Os and Ru, may reflect variable loss of Ir as volatile IrF6 in some of the most magnesian samples. Rhenium is negatively correlated with MgO, behaving as an incompatible trace element. Its behavior in the lava lake is complicated by apparent volatile loss of Re, as suggested by a decrease in Re concentration with time of quenching for lake samples vs. eruption samples. Platinum and Pd concentrations are negatively, albeit weakly, correlated with MgO, so these elements were modestly incompatible during crystallization of the major silicate phases. Palladium contents peaked before precipitation of immiscible sulfide liquid, however, and decline sharply in the most differentiated samples. In contrast, Pt appears to have been unaffected by sulfide precipitation. Microprobe data confirm that Pd entered the sulfide liquid before Re, and that Pt is not strongly chalcophile in this system. Occasional high Pt values

Increase in platinum group elements in Mexico City as revealed from growth rings of Taxodium mucronatum ten.

Science.gov (United States)

Morton-Bermea, Ofelia; Beramendi-Orosco, Laura; Martínez-Reyes, Ángeles; Hernández-Álvarez, Elizabeth; González-Hernández, Galia

2016-02-01

Tree rings may be used as indicators of contamination events providing information on the chronology and the elemental composition of the contamination. In this framework, we report PGEs enrichment in growth rings of Taxodium mucronatum ten for trees growing in the central area of Mexico City as compared to trees growing in a non-urban environment. Concentrations of PGE were determined by ICP-MS analysis on microwave-digested tree rings. The element found in higher concentrations was Pd (1.13-87.98 μg kg(-1)), followed by Rh (0.28-36.81 μg kg(-1)) and Pt (0.106-7.21 μg kg(-1)). The concentration trends of PGEs in the tree-ring sequences from the urban area presented significant correlation values when comparing between trees (r between 0.618 and 0.98, P < 0.025) and between elements within individual trees (r between 0.76 and 0.994, P < 0.01). Furthermore, a clear increase was observed for rings after 1997, with enrichment of up to 60 times the mean concentration found for the sequence from the non-urban area and up to 40 times the mean concentration for the pre-1991 period in the urban trees. These results also demonstrate the feasibility of applying T. mucronatum ten to be used as a bioindicator of the increase in PGE in urban environments.

Study on the occurrence of platinum in Xinjie Cu-Ni sulfide deposits by a combination of SPM and NAA

International Nuclear Information System (INIS)

Li Xiaolin; Zhu Jieqing; Lu Rongrong; Gu Yingmei; Wu Xiankang; Chen Youhong

1997-01-01

A combination of neutron-activation analysis (NAA) and scanning proton microprobe (SPM) was used to study the distribution of platinum-group elements (PGEs) in rocks and ores from Xinjie Cu-Ni deposit. The minimum detection limits of PGEs by NAA had been much improved by means of a nickel-sulfide fire-assay technique for pre-concentration of PGEs in the ore samples. A simple and effective method was developed for true element mapping in SPM experiments. A pair of moveable absorption filters was set up in the target chamber for high sensitivities of both major and trace elements. The bulk analysis results by NNA indicated that the PGE mineralization occurred at the base of Xinjie layered intrusion in clino-pyroxenite rocks and the Cu-Ni sulfide minerals disseminated within the rocks had high abundance level of PGEs. However, the micro-PIXE analysis of the Cu-Ni sulfide mineral grains did not find PGEs above the MDL of (6-9) x 10 -6 for Rh, Ru and Pd, and 6- x 10 -6 for Pt. The search for platinum occurrence in sulfide minerals was followed by scanning analysis of SPM when some smaller platinum enriched grains were found in the sulfide minerals. The microscopic analysis results suggested that platinum occurred in the Cu-Ni sulfide matrix as independent arsenide mineral grains. The chemical formula of the arsenide sperrylite was PtAs2. The information of the platinum occurrence was helpful to future mineralogical research and mineral processing and beneficiation of the Cu-Ni deposit

Study on the occurrence of platinum in Xinjie CuNi sulfide deposits by a combination of SPM and NAA

Science.gov (United States)

Li, Xiaolin; Zhu, Jieqing; Lu, Rongrong; Gu, Yingmei; Wu, Xiankang; Chen, Youhong

1997-07-01

A combination of neutron-activation analysis (NAA) and scanning proton microprobe (SPM) was used to study the distribution of platinum-group elements (PGEs) in rocks and ores from Xinjie CuNi deposit. The minimum detection limits of PGEs by NAA had been much improved by means of a nickel-sulfide fire-assay technique for pre-concentration of PGEs in the ore samples. A simple and effective method was developed for true element mapping in SPM experiments. A pair of moveable absorption filters was set up in the target chamber for high sensitivities of both major and trace elements. The bulk analysis results by NNA indicated that the PGE mineralization occurred at the base of Xinjie layered intrusion in clinopyroxenite rocks and the CuNi sulfide minerals disseminated within the rocks had high abundance level of PGEs. However, the micro-PIXE analysis of the CuNi sulfide mineral grains did not find PGEs above the MDL of 6-9 ppm for Rh, Ru and Pd, and 60 ppm for Pt. The search for platinum occurrence in sulfide minerals was followed by scanning analysis of SPM when some smaller platinum enriched grains were found in the sulfide minerals. The microscopic analysis results suggested that platinum occurred in the CuNi sulfide matrix as independent arsenide mineral grains. The chemical formula of the arsenide sperrylite was PtAs 2. The information of the platinum occurrence was helpful to future mineralogical research and mineral processing and beneficiation of the CuNi deposit.

Behaviour of palladium(II), platinum(IV), and rhodium(III) in artificial and natural waters: Influence of reactor surface and geochemistry on metal recovery

Energy Technology Data Exchange (ETDEWEB)

Cobelo-Garcia, Antonio [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom)]. E-mail: antonio.cobelo-garcia@plymouth.ac.uk; Turner, Andrew [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Millward, Geoffrey E. [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Couceiro, Fay [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom)

2007-03-07

The recovery of dissolved platinum group elements (PGE: Pd(II), Pt(IV) and Rh(III)) added to Milli-Q[reg] water, artificial freshwater and seawater and filtered natural waters has been studied, as a function of pH and PGE concentration, in containers of varying synthetic composition. The least adsorptive and/or precipitative loss was obtained for borosilicate glass under most of the conditions employed, whereas the greatest loss was obtained for low-density polyethylene. Of the polymeric materials tested, the adsorptive and/or precipitative loss of PGE was lowest for fluorinated ethylene propylene (Teflon[reg]). The loss of Pd(II) in freshwater was significant due to its affinity for surface adsorption and its relatively low solubility. The presence of natural dissolved organic matter increases the recovery of Pd(II) but enhances the loss of Pt(IV). The loss of Rh(III) in seawater was significant and was mainly due to precipitation, whereas Pd(II) recovery was enhanced, compared to freshwater, because of its complexation with chloride. The results have important implications regarding protocols employed for sample preservation and controlled laboratory experiments used in the study of the speciation and biogeochemical behaviour of PGE.

Distribution and PGE mineralization in the formation of chromitite in ophiolite complexes (Ospina-Kitoi Kharanur and ultrabasic massifs of Eastern Sayan, Sousern Siberia)

Science.gov (United States)

Kiseleva, Olga; Zhmodik, Sergei

2015-04-01

New study of PGE in restitic ultrabasic (Kharanur and Ospin-Kitoi) massifs from North and South branches (Dobretsov et al., 1985) of the ophiolite complexes in south-eastern part of the Eastern Sayan show their presence in chromitites of both branches belonging to the different geodynamic settings. Modern concepts model includes several mechanisms of podiform chromitite origin reflected in the chemistry of Cr-spinels (Arai, Yurimoto, 1994; Ballhaus, 1998; Uysal et al., 2009 et al.): 1) partial melting of upper mantle rocks, 2) mixing of primitive melts with melts enriched in SiO2, 3) melt-rock interaction. We estimated the types of interaction of mafic melts with mantle peridotites, with the formation of chromite bodies. For ore chrome spinelides from northern branch (Al2O3) melt = 8 - 14 wt%, (TiO2) melt = 0 - 0,4 wt%, (Fe/Mg) melt = 0,5 - 2,4; Southern branch (Al2O3) melt = 10 - 13 wt%, (TiO2) melt = 0,1 wt%, (Fe/Mg) melt = 0,3 - 1 (Kiseleva, 2014). There are two types of PGE distribution Os-Ir-Ru (I) and Pt-Pd (II). Type I chromitites (mid-Al#Cr-spinels) revealed only Os-Ir-Ru distributions; type II (low-Al#Cr spinelides) show both Os-Ir-Ru and (Pt-Pd) distributions (Kiseleva et al., 2012, 2014). PGE distribution in ultramafic peridotites and chromitites reflects PGE fractionation during partial melting (Barnes et al., 1985; Rehkämper et al., 1997). Processes bringing to extreme fractionation of PGE, may be associated with fluid-saturated supra subduction environment where melting degree near 20% and above is sufficient for the release of PGE from the mantle source (Dick, Bullen, 1984; Naldrett, 2010). Enrichment in PPGE together with a high content of IPGE in same chromite bodies is attributed to the second step of melting, and formation of S-enriched and saturated in PGE melts (Hamlyn, Keays, 1986; Prichard et al., 1996). For type I chromitites platinum group minerals (PGM) are presented by Os-Ir-Ru system. In type II chromitites PGM are represented by Os

Platinum group elements in the environment: emissions and exposure.

Science.gov (United States)

Dubiella-Jackowska, Aleksandra; Polkowska, Zaneta; Namieńnik, Jacek

2009-01-01

PGEs (Pt, Pd, Ru, Ir, and Os) are a relatively new group of anthropogenic pollutants. Specific useful properties of these metals (high resistance to chemical corrosion over a wide range of temperatures, high melting point, high mechanical resistance, and high plasticity) have fomented rapid growth of new and existing applications in various economic and industrial sectors. These metals are not only used in the chemical, petrochemical, electrical, and electronics industries but also PGE use, in various industries, has dramatically increased emissions of these metals to the environment; emissions from vehicle catalytic converters and hospital wastewater discharges are particularly significant. The environmental benefits of using PGEs in vehicle catalytic converters are clear. These metals catalyze the conversion of toxic constituents of exhaust fumes (CO, HCs, NOxs) to water, CO2, and molecular nitrogen. As a result of adverse physico-chemical and mechanical influences on the catalyst surface, PGEs are released from this layer and are emitted into the environment in exhaust fumes. Research results indicate that the levels of such emissions are rather low (ng km(-1)). However, recent data show that certain chemical forms of PGEs emitted from vehicles are, or may be, bioavailable. Hence, the potential for PGEs to bioaccumulate in different environmental compartments should be studied, and, if necessary, addressed. The use of Pt in anticancerous drug preparations also contributes to environmental burdens. Pt, when administered as a drug, is excreted in a patient's urine and, as a consequence, has been observed in hospital and communal wastewater discharges. Few studies have been published that address bioavailability, mode of penetration into live organisms, or environmental fate of PGEs. The toxic effect of these metals on living organisms, including humans, is still in dispute and incompletely elucidated. Contrary to some chlorine complexes of Pt, which most

GIS-based identification of areas with mineral resource potential for six selected deposit groups, Bureau of Land Management Central Yukon Planning Area, Alaska

Science.gov (United States)

Jones, James V.; Karl, Susan M.; Labay, Keith A.; Shew, Nora B.; Granitto, Matthew; Hayes, Timothy S.; Mauk, Jeffrey L.; Schmidt, Jeanine M.; Todd, Erin; Wang, Bronwen; Werdon, Melanie B.; Yager, Douglas B.

2015-01-01

This study, covering the Bureau of Land Management (BLM) Central Yukon Planning Area (CYPA), Alaska, was prepared to aid BLM mineral resource management planning. Estimated mineral resource potential and certainty are mapped for six selected mineral deposit groups: (1) rare earth element (REE) deposits associated with peralkaline to carbonatitic intrusive igneous rocks, (2) placer and paleoplacer gold, (3) platinum group element (PGE) deposits associated with mafic and ultramafic intrusive igneous rocks, (4) carbonate-hosted copper deposits, (5) sandstone uranium deposits, and (6) tin-tungsten-molybdenum-fluorspar deposits associated with specialized granites. These six deposit groups include most of the strategic and critical elements of greatest interest in current exploration.

Induction of heat shock proteins (hsp70) in the zebra mussel (Dreissena polymorpha) following exposure to platinum group metals (platinum, palladium and rhodium): Comparison with lead and cadmium exposures

Energy Technology Data Exchange (ETDEWEB)

Singer, Christoph [Zoologisches Institut I-Oekologie, Universitaet Karlsruhe, Geb. 07.01, Kornblumenstrasse 13, D-76131 Karlsruhe (Germany); Zimmermann, Sonja [Zoologisches Institut I-Oekologie, Universitaet Karlsruhe, Geb. 07.01, Kornblumenstrasse 13, D-76131 Karlsruhe (Germany); Sures, Bernd [Zoologisches Institut I-Oekologie, Universitaet Karlsruhe, Geb. 07.01, Kornblumenstrasse 13, D-76131 Karlsruhe (Germany)]. E-mail: dc11@rz.uni-karlsruhe.de

2005-10-05

An increasing number of papers concentrate on the availability and uptake of platinum group elements (PGE) by different organisms. These metals are discharged into the environment from different anthropogenic sources, such as automobile catalytic converters, hospitals and other medical institutions. As the effects of these precious metals on organisms remain unclear, the induction of heat shock proteins (hsp70) in zebra mussels (Dreissena polymorpha) following exposure to soluble salts of platinum, palladium and rhodium was compared with the hsp70 induction in mussels following exposure to cadmium and lead. Mussels were sampled weekly during a period of 10 weeks and analyzed for their metal concentration and their hsp70 level. Highest metal uptake was found for Cd, followed by Pt, Pb and Pd. Rh demonstrated the lowest uptake rate. A clear time-dependent increase of hsp70 levels occurred in all exposed mussels. Concentrations of hsp70 started to rise between days 18 and 25, except for the Pt-exposed group, where the initial increase was between days 25 and 32. All groups reached maximal hsp70 concentrations at day 39. Subsequently, hsp70 levels decreased to initial levels for the remaining exposure period. Threshold metal levels for the hsp70 induction varied among the metals and increased in the order: Rh < Pd {<=} Pb < Pt < Cd. Highest hsp70 values were found for mussels exposed to Pd, with a 25-fold higher level than in the controls, followed by Pt- and Rh-exposed mussels, which showed a 19-fold increase. The hsp70 levels of the mussels exposed to Cd and Pb were much lower, showing 6- and 12-fold higher values than the control, respectively. The clear induction of hsp70 due to exposure to Pt, Pd and Rh gives evidence for strong cellular effects of these metals, especially, when compared with lead and cadmium. Among the metals tested, Pd seems to have the highest potential as inducer for hsp70 production due to its low threshold level in combination with the

Induction of heat shock proteins (hsp70) in the zebra mussel (Dreissena polymorpha) following exposure to platinum group metals (platinum, palladium and rhodium): Comparison with lead and cadmium exposures

International Nuclear Information System (INIS)

Singer, Christoph; Zimmermann, Sonja; Sures, Bernd

2005-01-01

An increasing number of papers concentrate on the availability and uptake of platinum group elements (PGE) by different organisms. These metals are discharged into the environment from different anthropogenic sources, such as automobile catalytic converters, hospitals and other medical institutions. As the effects of these precious metals on organisms remain unclear, the induction of heat shock proteins (hsp70) in zebra mussels (Dreissena polymorpha) following exposure to soluble salts of platinum, palladium and rhodium was compared with the hsp70 induction in mussels following exposure to cadmium and lead. Mussels were sampled weekly during a period of 10 weeks and analyzed for their metal concentration and their hsp70 level. Highest metal uptake was found for Cd, followed by Pt, Pb and Pd. Rh demonstrated the lowest uptake rate. A clear time-dependent increase of hsp70 levels occurred in all exposed mussels. Concentrations of hsp70 started to rise between days 18 and 25, except for the Pt-exposed group, where the initial increase was between days 25 and 32. All groups reached maximal hsp70 concentrations at day 39. Subsequently, hsp70 levels decreased to initial levels for the remaining exposure period. Threshold metal levels for the hsp70 induction varied among the metals and increased in the order: Rh < Pd ≤ Pb < Pt < Cd. Highest hsp70 values were found for mussels exposed to Pd, with a 25-fold higher level than in the controls, followed by Pt- and Rh-exposed mussels, which showed a 19-fold increase. The hsp70 levels of the mussels exposed to Cd and Pb were much lower, showing 6- and 12-fold higher values than the control, respectively. The clear induction of hsp70 due to exposure to Pt, Pd and Rh gives evidence for strong cellular effects of these metals, especially, when compared with lead and cadmium. Among the metals tested, Pd seems to have the highest potential as inducer for hsp70 production due to its low threshold level in combination with the

Instrumental neutron activation analysis of a nickel sulfide fire assay button to determine the platinum group elements and gold

Energy Technology Data Exchange (ETDEWEB)

Asif, M.; Parry, S.J.; Malik, H. (Imperial College of Science, Technology and Medicine, Silwood Park, Ascot (United Kingdom). Centre for Analytical Research in the Environment)

1992-08-01

Platinum group elements and gold were determined in reference materials SARM 7 and MA 1b using fire assay with 0.5 g of nickel prior to neutron activation analysis. The method is simple and rapid, avoiding the dissolution step where losses occur, particularly of gold. The problem of standardizing the button mass was overcome by using a spiking technique. The method is best suited to samples with little or no copper, when the detection limits can be as low as 0.002, 0.025, 0.018, 0.0002, 0.002, 0.020 and 0.2 mg kg[sup -1] for Rh, Pd, Pt, Ir, Au, Os and Ru, respectively. (author).

Activation analysis for platinum in gold and metals of the platinum group through 199Au

International Nuclear Information System (INIS)

Foerster, H.

1976-01-01

Platinum was determined in gold and in metals of the platinum group through 199 Au by activation analysis. The matrix was separated at the end of irradiation before the daughter nuclide was formed. Gold was separated by extraction with MIBK from 1

Recent strikes in South Africa’s platinum-group metal mines: effects upon world platinum-group metal supplies

Science.gov (United States)

Yager, Thomas R.; Soto-Viruet, Yadira; Barry, James J.

2012-01-01

The recent labor disputes over wages and working conditions that have affected South Africa’s three leading platinum-group metal (PGM) producers have affected an industry already plagued by market pressures and labor unrest and raised the specter of constraints in the world’s supply of these metals. Although low demand for these metals in 2011 and 2012 helped to offset production losses of recent years, and particularly those losses caused by the strikes in 2012, a prolonged resumption of strikes could cause severe shortages of iridium, platinum, rhodium, ruthenium, and, to a lesser extent, palladium.

A 50-year record of platinum, iridium, and rhodium in Antarctic snow: volcanic and anthropogenic sources.

Science.gov (United States)

Soyol-Erdene, Tseren-Ochir; Huh, Youngsook; Hong, Sungmin; Hur, Soon Do

2011-07-15

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) (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.

Bioaccumulation of platinum group metals in dolphins, Stenella sp ...

African Journals Online (AJOL)

Platinum group metals (PGMs) concentrations were measured in the tissues= of dolphins (Stenella sp.) caught along the Ghanaian coastline. Tissues from specimens caught by fishermen from Dixcove, western Ghana, were analysed in 2006 for palladium (Pd), platinum (Pt) and rhodium (Rh) using the Neutron Activation ...

Micrometer- and nanometer-sized platinum group nuggets in micrometeorites from deep-sea sediments of the Indian Ocean

Digital Repository Service at National Institute of Oceanography (India)

Rudraswami, N.G.; Parashar, K.; ShyamPrasad, M.

We examined 378 micrometeorites collected from deep-sea sediments of the Indian Ocean of which 175, 180, and 23 are I-type, S-type, and G-type, respectively. Of the 175 I-type spherules, 13 contained platinum group element nuggets (PGNs...

Reliability assessment of MVP-BURN and JENDL-4.0 related to nuclear transmutation of light platinum group elements

Science.gov (United States)

Terashima, Atsunori; Nilsson, Mikael; Ozawa, Masaki; Chiba, Satoshi

2017-09-01

The Aprés ORIENT research program, as a concept of advanced nuclear fuel cycle, was initiated in FY2011 aiming at creating stable, highly-valuable elements by nuclear transmutation from ↓ssion products. In order to simulate creation of such elements by (n, γ) reaction succeeded by β- decay in reactors, a continuous-energy Monte Carlo burnup calculation code MVP-BURN was employed. Then, it is one of the most important tasks to con↓rm the reliability of MVP-BURN code and evaluated neutron cross section library. In this study, both an experiment of neutron activation analysis in TRIGA Mark I reactor at University of California, Irvine and the corresponding burnup calculation using MVP-BURN code were performed for validation of the simulation on transmutation of light platinum group elements. Especially, some neutron capture reactions such as 102Ru(n, γ)103Ru, 104Ru(n, γ)105Ru, and 108Pd(n, γ)109Pd were dealt with in this study. From a comparison between the calculation (C) and the experiment (E) about 102Ru(n, γ)103Ru, the deviation (C/E-1) was signi↓cantly large. Then, it is strongly suspected that not MVP-BURN code but the neutron capture cross section of 102Ru belonging to JENDL-4.0 used in this simulation have made the big di↑erence as (C/E-1) >20%.

Automated installation for atomic emission determination of gold, silver and platinum group metals

International Nuclear Information System (INIS)

Zayakina, S.B.; Anoshin, G.N.; Gerasimov, P.A.; Smirnov, A.V.

1999-01-01

An automated installation for the direct atomic emission determination of silver, gold and platinum-group metals (Ru) in geological and geochemical materials with software for automated data acquisition and handling is designed and developed. The installation consists of a DFS-458 diffraction spectrograph, a MAES-10 multichannel analyzer of emission spectra, and a dual-jet plasmatron. A library of spectral lines of almost all elements excited in the dual-jet plasmatron is complied [ru

Comparison of misoprostol (pge1) analogue with dinoprostone (pge2) for induction of labour

International Nuclear Information System (INIS)

Tahir, N.; Afzal, B.; Chohan, S.

2013-01-01

Objective: To compare the results of induction of labour with misoprostol (PGE1 analogue) with dinoprostone (PGE2 analogue) in terms of induction delivery interval, mode of delivery, and the need for oxytocin augmentation. Setting: Department of Obstetrics and Gynaecology, Combined Military Hospital, Rawalpindi. Duration of Study: Six months Study Design: Randomized controlled trial. Subject and Method: Total 100 subjects were included in this study. These patients were divided in groups-A and B. Group-A was induced with prostin tablet i.e. dinoprostone PGE2 3 mg tablets maximum of 2 doses, 6 hours apart. Group-B induced with prosotec 50 mu gm 4 hourly, 4 doses. The subjects were full term pregnant women who were either primigravida, 2nd or 3rd gravid and had bishop score less than 5. Results: The patients included in the study were between the ages of 19 to 37 years. The mean age of group-A was 26.72 +- 4.62 years and of group-B was 28.4 +- 4.94 years (p value > 0.05). All the patients in both groups were between 37 to 42 weeks of gestation. The mean gestational age of group-A was 39.74 +- 2.09 weeks and in group-B it was 39.62 +- 1.55 weeks (p > 0.05). Oxytocin augmentation was required in late 1st stage and 2nd stage in group-A in 68% cases but it was required in only 30% cases in group-B cases. The maximum duration of labour was more than 11 hours in 24% cases in group-A but only 6% in group-B. Conclusion: Misoprostol (PGE1 analogue) is a useful drug for labour induction. There is short induction delivery interval and reduced need for the use of oxytocin augmentation. There are also less failure rates of induction with misoprostol. Rate of instrumental delivery and caesarean section is also less. (author)

Reliability assessment of MVP-BURN and JENDL-4.0 related to nuclear transmutation of light platinum group elements

Directory of Open Access Journals (Sweden)

Terashima Atsunori

2017-01-01

Full Text Available The Aprés ORIENT research program, as a concept of advanced nuclear fuel cycle, was initiated in FY2011 aiming at creating stable, highly-valuable elements by nuclear transmutation from ↓ssion products. In order to simulate creation of such elements by (n, γ reaction succeeded by β− decay in reactors, a continuous-energy Monte Carlo burnup calculation code MVP-BURN was employed. Then, it is one of the most important tasks to con↓rm the reliability of MVP-BURN code and evaluated neutron cross section library. In this study, both an experiment of neutron activation analysis in TRIGA Mark I reactor at University of California, Irvine and the corresponding burnup calculation using MVP-BURN code were performed for validation of the simulation on transmutation of light platinum group elements. Especially, some neutron capture reactions such as 102Ru(n, γ103Ru, 104Ru(n, γ105Ru, and 108Pd(n, γ109Pd were dealt with in this study. From a comparison between the calculation (C and the experiment (E about 102Ru(n, γ103Ru, the deviation (C/E-1 was signi↓cantly large. Then, it is strongly suspected that not MVP-BURN code but the neutron capture cross section of 102Ru belonging to JENDL-4.0 used in this simulation have made the big di↑erence as (C/E-1 >20%.

Isotope dilution inductively coupled plasma quadrupole mass spectrometry in connection with a chromatographic separation for ultra trace determinations of platinum group elements (Pt, Pd, Ru, Ir) in environmental samples.

Science.gov (United States)

Müller, M; Heumann, K G

2000-09-01

An isotope dilution inductively coupled plasma quadrupole mass spectrometric (ID-ICP-QMS) method was developed for the simultaneous determination of the platinum group elements Pt, Pd, Ru, and Ir in environmental samples. Spike solutions, enriched with the isotopes 194Pt, 108Pd, 99Ru, and 191Ir, were used for the isotope dilution step. Interfering elements were eliminated by chromatographic separation using an anion-exchange resin. Samples were dissolved with aqua regia in a high pressure asher. Additional dissolution of possible silicate portions by hydrofluoric acid was usually not necessary. Detection limits of 0.15 ng x g(-1), 0.075 ng x g(-1), and 0.015 ng x g(-1) were achieved for Pt, Pd, Ru, and Ir, respectively, using sample weights of only 0.2 g. The reliability of the ID-ICP-QMS method was demonstrated by analyzing a Canadian geological reference material and by participating in an interlaboratory study for the determination of platinum and palladium in a homogenized road dust sample. Surface soil, sampled at different distances from a highway, showed concentrations in the range of 0.1-87 ng x g(-1). An exponential decrease of the platinum and palladium concentration with increasing distance and a small anthropogenic contribution to the natural background concentration of ruthenium and iridium was found in these samples.

Toxicity of platinum, palladium and rhodium to Daphnia magna in single and binary metal exposure experiments.

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Zimmermann, Sonja; Wolff, Carolina; Sures, Bernd

2017-05-01

Mainly due to automobile traffic, but also due to other sources, the platinum group elements (PGE) platinum (Pt), palladium (Pd) and rhodium (Rh) are introduced into aquatic biotopes where they accumulate in sediments of lakes and rivers. However, the toxicity of these noble metals to aquatic organisms is not well understood and especially toxicity studies under standardized condition are lacking. Thus, the toxicity of Pt, Pd and Rh to Daphnia magna was tested in single metal exposure experiments according to OECD guideline 202. Immobility and lethality was recorded after 24 h and 48 h of exposure and EC 50 and LC 50 , respectively, were determined. As the nominal exposure concentration of Pd differed significantly from the quantified concentration, the control of the real exposure concentration by chemical analysis is mandatory, especially for Pd. The toxicity decreased in the order Pd > Pt ≫ Rh with e.g. LC 50 (48 h) values of 14 μg/L for Pd, 157 μg/L for Pt and 56,800 μg/L for Rh. The exposure period had a clear effect on the toxicity of Pt, Pd and Rh. For Pt and Rh the endpoint immobility was more sensitive than the endpoint lethality whereas Pd toxicity was similar for both endpoints. The Hill slopes, which are a measure for the steepness of the concentration-response curves, showed no significant discrepancies between the different metals. The binary metal exposure to Pt and Pd revealed a more-than-additive, i.e. a synergistic toxicity using the toxic unit approach. The present study is a start to understand the toxicity of interacting PGE. The modes of action behind the synergistic effect are unclear. Copyright © 2017 Elsevier Ltd. All rights reserved.

Study of the influence of platinum, palladium and rhodium on duckweed (Lemna minor).

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Bednarova, Ivana; Mikulaskova, Hana; Havelkova, Barbora; Strakova, Lenka; Beklova, Miroslava; Sochor, Jiri; Hynek, David; Adam, Vojtech; Kizek, Rene

2014-01-01

Road traffic pollutants and the residues of cytostatics that are widely used in anti-cancer therapy are a significant sources of platinum group elements (PGE; Pt, Pd and Rh) in environment. These metals can migrate into sewage and thus pollute surface waters. The purpose of our study was to evaluate the effect of PtCl4 on the antioxidant and enzymatic activity of duckweed (Lemna minor), a bioindicator of the aquatic environment. The study was performed using a 7-day conventional test based on the OECD 221 (CSN EN ISO 20079)--Lemna sp. Growth Inhibition Test. We also conducted a microbiotest to analyse the effects of PtC4, PdCl2 and RhCl3 on the morphology and vegetative growth of colonies of this plant and compared their inhibitory effects during the microbiotest. We observed inhibition of colony growth and clear morphological changes. Antioxidant and enzymatic activities increased with platinum doses increased. The 168hEC50 of PtCl4 was 12.16 μM (95% confidence interval = 9.88-14.44) and the 168hEC50 of PdCl2 was 50.39 (95% confidence interval = 23.83-76.96). The greatest inhibition of growth by RhCl3 was observed at 25 μM. The obtained results suggest that L. minor phytotoxicity tests should be widely used in the biomonitoring.

pH-dependent release of trace elements including platinum group elements (PGEs) from gasoline and diesel catalysts

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Sucha, Veronika; Mihaljevic, Martin; Ettler, Vojtech; Strnad, Ladislav

2014-05-01

The release of trace metals and platinum group elements (PGEs) from automobile exhaust catalysts represents a remarkable source of higly dispersed environmental contamination. Especially, PGEs have shown increasing research interest due to their possible bioaccessibility. In our research, we focused on leaching behaviour of trace metals from gasoline and diesel automobile catalysts. While catalysts for gasoline engines contain a mixture of Pt-Pd-Rh or Pd-Rh, catalysts for diesel engines are composed only of Pt. We used dust from two crushed gasoline and two crushed diesel catalysts (new and aged). The dust of gasoline catalysts contains significant concentrations of Pt (700 mg.kg-1), Pd (11 000 mg.kg-1) and Rh (700 mg.kg-1). And the dust of diesel catalysts are composed of Pt (3 900 mg.kg-1) and they contains negligible amounts of Pd dan Rh (leaching of trace metals from dust we used pH-stat leaching test according to the European standard CEN/TS 14997. The concentrations of cations: PGEs (Pt, Pd a Rh), K, Na, Ca, Mg, Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, La and Ce were determined by inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectrometry (AAS), and anions: F-, Cl-, SO42- and NO3- by high-performance liquid chromatography. Although the dusts from catalysts were relatively stable to acid/base influence, the leaching of trace metals from catalysts showed a dependence on pH. Generally, the highest concentrations were released under acidic conditions. The leaching of PGEs was higher for Pt in diesel catalysts and for Pd and Rh in gasoline catalysts. The highest concentrations of Zn and Pb were observed in old catalysts. The rare earth metals were released more from gasoline catalysts. Catalysts particles represent health risk especially with respect to their PGEs contents.

Development of radioactive platinum group metal catalysts

International Nuclear Information System (INIS)

Chung, H.S.; Kim, Y.S.; Kim, Y.E.

1999-03-01

The fission product nuclides generated during the irradiation of reactor fuel include many useful elements, among them platinum group metals such as ruthenium, rhodium and palladium which are of great industrial importance, occur rarely in nature and are highly valuable. In this research, the authors reviewed various PGM recovery methods. Recovery of palladium from seven-component simulated waste solutions was conducted by selective precipitation method. The recovery yield was more than 99.5% and the purity of the product was more than 99%. Wet-proof catalyst was prepared with the recovered palladium. The specific surface area of the catalyst support was more than 400m 2 /g. The content of palladium impregnated on the support was 1 to 10 wt. %. Hydrogen isotope exchange efficiency of more than 93% to equilibrium with small amount of the catalyst was obtained. It was turned out possible to consider using such palladium or other very low active PGM materials in applications where its activity is unimportant as in nuclear industries. (author). 86 refs., 44 tabs., 88 figs

Development of radioactive platinum group metal catalysts

Energy Technology Data Exchange (ETDEWEB)

Chung, H.S.; Kim, Y.S.; Kim, Y.E. [and others

1999-03-01

The fission product nuclides generated during the irradiation of reactor fuel include many useful elements, among them platinum group metals such as ruthenium, rhodium and palladium which are of great industrial importance, occur rarely in nature and are highly valuable. In this research, the authors reviewed various PGM recovery methods. Recovery of palladium from seven-component simulated waste solutions was conducted by selective precipitation method. The recovery yield was more than 99.5% and the purity of the product was more than 99%. Wet-proof catalyst was prepared with the recovered palladium. The specific surface area of the catalyst support was more than 400m{sup 2}/g.The content of palladium impregnated on the support was 1 to 10 wt. %. Hydrogen isotope exchange efficiency of more than 93% to equilibrium with small amount of the catalyst was obtained. It was turned out possible to consider using such palladium or other very low active PGM materials in applications where its activity is unimportant as in nuclear industries. (author). 86 refs., 44 tabs., 88 figs.

Recycling of platinum group metals from the automotive catalysts; Reciclagem de metais do grupo da platina proveniente de catalisadores automotivos

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Benevit, Mariana; Petter, Patricia Melo Halmenschlager; Veit, Hugo Marcelo, E-mail: patymhp@yahoo.com.br [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Faculdade de Engenharia. Departamento de Materiais

2014-07-01

Currently it is very important to use alternative sources of raw material for obtaining metals, avoiding the traditional mining. This work aims to characterize and evaluate the recoverability of platinum group metals present in automotive catalysts. Thus, the catalysts were divided into two groups: the first was catalysts used in 1.0 cars and the second was catalyst used in 2.0 cars. DRX and FRX techniques and chemical analysis performed by ICP/OES was used to characterized these materials. The results showed that there is a significant amount of platinum group elements in catalyst waste, which can be separated and reused. In the next step, hydro and pyrometallurgical routes, for metals extraction from catalyst waste, will be studied. (author)

Platinum group metal nitrides and carbides: synthesis, properties and simulation

International Nuclear Information System (INIS)

Ivanovskii, Alexander L

2009-01-01

Experimental and theoretical data on new compounds, nitrides and carbides of the platinum group 4d and 5d metals (ruthenium, rhodium, palladium, osmium, iridium, platinum), published over the past five years are summarized. The extreme mechanical properties of platinoid nitrides and carbides, i.e., their high strength and low compressibility, are noted. The prospects of further studies and the scope of application of these compounds are discussed.

A survey of the determination of the platinum group elements.

Science.gov (United States)

Kallmann, S

1987-08-01

The platinum-group metals (PGMs), Ru, Rh, Pd, Os, Ir and Pt, are widely used as catalysts in petroleum and chemical processes. They find wide applications in automotive exhaust-gas control converters and are of immense importance to the electronics industry. They are found in many items of jewellery and serve to an increasing extent as a form of investment. The PGMs are extracted in minute quantities from a limited number of ores, found mainly in S. Africa and the USSR. They are concentrated and separated from each other by elaborate chemical processes. Because of their great intrinsic value (Pt $650 per oz; Rh $1400 per oz), the recycling of the PGMs from literally hundreds of different forms of scrap is an essential factor in the overall management of the PGM economy. In this survey emphasis is placed on the need to tailor the analytical method according to (a) the environment in which the PGMs occur, (b) the individual PGM concentrations, and (c) the desired sensitivity and precision. The factors which determine the choice of chemical, physicochemical and/or instrumental approaches are discussed. They are further commented on in extensive presentations of dissolution and separation techniques and methods for the final measurement of individual PGMs. Appendices are provided which present the compositions and sources of the products most frequently encountered in PGM analysis, along with information on methods of decomposition, separations required, type of separation, and final determination.

As, Bi, Hg, S, Sb, Sn and Te geochemistry of the J-M Reef, Stillwater Complex, Montana: constraints on the origin of PGE-enriched sulfides in layered intrusions

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Zientek, M.L.; Fries, T.L.; Vian, R.W.

1990-01-01

The J-M Reef is an interval of disseminated sulfides in the Lower Banded series of the Stillwater Complex that is enriched in the platinum group elements (PGE). Palladium and Pt occur in solid solution in base-metal sulfides and as discrete PGE minerals. PGE minerals include sulfides, tellurides, arsenides, antimonides, bismuthides, and alloys with Fe, Sn, Hg, and Au. Several subpopulations can be delineated based on whole-rock chemical analyses for As, Bi, Cu, Hg, Pd, Pt, S, Sb and Te for samples collected from and adjacent to the J-M Reef. In general, samples from within the reef have higher Pt/Cu, Pd/Cu, Pd/Pt, Te/Bi and S/(Te+Bi) than those collected adjacent to the reef. Vertical compositional profiles through the reef suggest that Pd/Cu and Pt/Cu decrease systematically upsection from mineralized to barren rock. The majority of samples with elevated As, Sb and Hg occur adjacent to the reef, not within it, or in sulfide-poor rocks. Neither magma mixing nor fluid migration models readily explain why the minor quantities of sulfide minerals immediately adjacent to the sulfide-enriched layers that form the J-M Reef have different element ratios than the sulfide minerals that form the reef. If all the sulfides formed by exsolution during a magma mixing event and the modal proportion of sulfide now in the rocks are simply the result of mechanical processes that concentrated the sulfides into some layers and not others, then the composition of the sulfide would not be expected to be different. Models that rely upon ascending liquids or fluids are incompatible with the presence of sulfides that are not enriched in PGE immediately below or interlayered with the PGE-enriched sulfides layers. PGE-enriched postcumulus fluids should have reacted to the same extent with sulfides immediately outside the reef as within the reef. One explanation is that some of the sulfide minerals in the rocks outside the reef have a different origin than those that make up the reef. The

Critical metals (REE, Sc, PGE) in Ni laterites from Cuba and the Dominican Republic

Czech Academy of Sciences Publication Activity Database

Aiglsperger, T.; Proenza, J. A.; Lewis, J. F.; Labrador, M.; Svojtka, Martin; Rojas-Purón, A.; Longo, F.; Ďurišová, Jana

2016-01-01

Roč. 73, March 01 (2016), s. 127-147 ISSN 0169-1368 Institutional support: RVO:67985831 Keywords : Caribbean * Cuba * Dominican Republic * Falcondo mining area * Moa Bay mining area * Ni laterite * Platinum Group Elements * Rare Earth Elements * Scandium Subject RIV: DB - Geology ; Mineralogy Impact factor: 3.095, year: 2016

Gibbs Free Energy of Formation for Selected Platinum Group Minerals (PGM

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Spiros Olivotos

2016-01-01

Full Text Available Thermodynamic data for platinum group (Os, Ir, Ru, Rh, Pd and Pt minerals are very limited. The present study is focused on the calculation of the Gibbs free energy of formation (ΔfG° for selected PGM occurring in layered intrusions and ophiolite complexes worldwide, applying available experimental data on their constituent elements at their standard state (ΔG = G(species − ΔG(elements, using the computer program HSC Chemistry software 6.0. The evaluation of the accuracy of the calculation method was made by the calculation of (ΔGf of rhodium sulfide phases. The calculated values were found to be ingood agreement with those measured in the binary system (Rh + S as a function of temperature by previous authors (Jacob and Gupta (2014. The calculated Gibbs free energy (ΔfG° followed the order RuS2 < (Ir,OsS2 < (Pt, PdS < (Pd, PtTe2, increasing from compatible to incompatible noble metals and from sulfides to tellurides.

Trace- and rare-earth element geochemistry and Pb-Pb dating of black shales and intercalated Ni-Mo-PGE-Au sulfide ores in Lower Cambrian strata, Yangtze Platform, South China

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Jiang, Shao-Yong; Chen, Yong-Quan; Ling, Hong-Fei; Yang, Jing-Hong; Feng, Hong-Zhen; Ni, Pei

2006-08-01

The Lower Cambrian black shale sequence of the Niutitang Formation in the Yangtze Platform, South China, hosts an extreme metal-enriched sulfide ore bed that shows >10,000 times enrichment in Mo, Ni, Se, Re, Os, As, Hg, and Sb and >1,000 times enrichment in Ag, Au, Pt, and Pd, when compared to average upper continental crust. We report in this paper trace- and rare-earth-element concentrations and Pb-Pb isotope dating for the Ni-Mo-PGE-Au sulfide ores and their host black shales. Both the sulfide ores and their host black shales show similar trace-element distribution patterns with pronounced depletion in Th, Nb, Hf, Zr, and Ti, and extreme enrichment in U, Ni, Mo, and V compared to average upper crust. The high-field-strength elements, such as Zr, Hf, Nb, Ta, Sc, Th, rare-earth elements, Rb, and Ga, show significant inter-element correlations and may have been derived mainly from terrigenous sources. The redox sensitive elements, such as V, Ni, Mo, U, and Mn; base metals, such as Cu, Zn, and Pb; and Sr and Ba may have been derived from mixing of seawater and venting hydrothermal sources. The chondrite-normalized REE patterns, positive Eu and Y anomalies, and high Y/Ho ratios for the Ni-Mo-PGE-Au sulfide ores are also suggestive for their submarine hydrothermal-exhalative origin. A stepwise acid-leaching Pb-Pb isotope analytical technique has been employed for the Niutitang black shales and the Ni-Mo-PGE-Au sulfide ores, and two Pb-Pb isochron ages have been obtained for the black shales (531±24 Ma) and for the Ni-Mo-PGE-Au sulfide ores (521±54 Ma), respectively, which are identical and overlap within uncertainty, and are in good agreement with previously obtained ages for presumed age-equivalent strata.

Petrography and Geochemistry (Trace, Ree and Pge of Pedda Cherlo Palle Gabbro-Diorite Pluton, Prakasam Igneous Province, Andhra Pradesh, India

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Subramanyam K.S.V.

2015-09-01

Full Text Available Prakasam Igneous Province (PIP is an important geological domain in the Eastern Dharwar Craton (EDC, found in the junction zone between the EDC and Eastern Ghat Mobile Belt (EGMB. The Pedda Cherlo Palle (PCP gabbros are massive, leucocratic-mesocractic, and show cumulus textures with minerals plagioclase, cpx, and amphiboles. Compositionally, plagioclase is a labradorite-bytownite, cpx is diopside to augite, olivines are hyalosiderites and amphiboles are magnesiohornblendes. PCP gabbros have normal SiO2, high Al2O3, moderate to high TiO2, Na2O and medium Fe2O3, so, classified as subalkaline tholeiitic gabbros. Fractionated rare earth element (REE patterns, high abundance of large ion lithofile elements (LILE and transitional metals coupled with light REE (LREE relative enrichment over heavy REE (HREE and Nb are characteristics of partial melting of depleted mantle and melts that have undergone fractional crystalisation. These partial melts are enriched in LREE and LILE, due to the addition of slab derived sediment and fluids. PCP gabbros contain low abundance (5.1 to 24.6 ng/g of platinum group elements (PGE, and show an increase in the order Ir>Os>Pt>Ru»Pd>Rh. We propose that the subduction related intraoceanic island arc might have accreted to the southeastern margin of India to the east of Cuddapah basin in a collisional regime that took place during Ur to Rodinia amalgamations.

Platinum group metal recovery and catalyst manufacturing process

Energy Technology Data Exchange (ETDEWEB)

Chung, H. S.; Kim, Y. S.; Yoo, J. H.; Lee, H. S.; Ahn, D. H.; Kim, K. R.; Lee, S. H.; Paek, S. W.; Kang, H. S.

1998-03-01

The fission product nuclides generated during the irradiation of reactor fuel include many useful elements, among them platinum group metal such as ruthenium, rhodium and palladium which are of great industrial importance, occur rarely in nature and are highly valuable. In this research, the authors reviewed various PGM recovery methods. Recovery of palladium from seven-component simulated waste solution was conducted by selective precipitation method. The recovery yield was more than 99.5% and the purity of the product was more than 99%. Wet-proof catalyst was prepared with the recovered palladium. The specific surface area of the catalyst support was more than 400 m{sup 2}/g. The content of palladium impregnated on the support was 10 wt.%. Hydrogen isotope exchange efficiency of 93 % to equilibrium with small amount of the catalyst was obtained. It was turned out possible to consider using such palladium or other very low active PGM materials in applications where its actively is unimportant as in nuclear industries. (author). 63 refs., 38 tabs., 36 figs.

The role of sulfides in the fractionation of highly siderophile and chalcophile elements during the formation of martian shergottite meteorites

Science.gov (United States)

Baumgartner, Raphael J.; Fiorentini, Marco L.; Lorand, Jean-Pierre; Baratoux, David; Zaccarini, Federica; Ferrière, Ludovic; Prašek, Marko K.; Sener, Kerim

2017-08-01

The shergottite meteorites are ultramafic to mafic igneous rocks whose parental magmas formed from partial melting of the martian mantle. This study reports in-situ laser ablation inductively coupled plasma mass spectrometry analyses for siderophile and chalcophile major and trace elements (i.e., Co, Ni, Cu, As, Se, Ag, Sb, Te, Pb, Bi, and the highly siderophile platinum-group elements, PGE: Os, Ir, Ru, Rh, Pt and Pd) of magmatic Fe-Ni-Cu sulfide assemblages from four shergottite meteorites. They include three geochemically similar incompatible trace element- (ITE-) depleted olivine-phyric shergottites (Yamato-980459, Dar al Gani 476 and Dhofar 019) that presumably formed from similar mantle and magma sources, and one distinctively ITE-enriched basaltic shergottite (Zagami). The sulfides in the shergottites have been variably modified by alteration on Earth and Mars, as well as by impact shock-shock related melting/volatilization during meteorite ejection. However, they inherit and retain their magmatic PGE signatures. The CI chondrite-normalized PGE concentration patterns of sulfides reproduce the whole-rock signatures determined in previous studies. These similarities indicate that sulfides exerted a major control on the PGE during shergottite petrogenesis. However, depletions of Pt (and Ir) in sulfide relative to the other PGE suggest that additional phases such discrete Pt-Fe-Ir alloys have played an important role in the concentration of these elements. These alloys are expected to have enhanced stability in reduced and FeO-rich shergottite magmas, and could be a common feature in martian igneous systems. A Pt-rich PGM was found to occur in a sulfide assemblage in Dhofar 019. However, its origin may be related to impact shock-related sulfide melting and volatilisation during meteorite ejection. In the ITE-depleted olivine-phyric shergottites, positive relationships exist between petrogenetic indicators (e.g., whole-rock Mg-number) and most moderately to

Litho- and chemostratigraphy of the Flatreef PGE deposit, northern Bushveld Complex

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Grobler, D. F.; Brits, J. A. N.; Maier, W. D.; Crossingham, A.

2018-05-01

The Flatreef is a world-class platinum-group element (PGE) deposit recently discovered down-dip from existing mining and exploration operations on the northern limb of the Bushveld Complex. Current indicated resources stand at 42 Moz PGE (346 Mt with 3.8 g/t Pt+Pd+Rh+Au, 0.32% Ni and 0.16% Cu) which, in the case of Pt, is equivalent to 10 years global annual production, making it one of the largest PGE deposits on earth. The grade and thickness of the Flatreef mineralised interval is highly unusual, with some drill core intersections containing up to 4.5 g/t Pt+Pd+Rh+Au over 90 m in drill core. Here, we document the down-dip and along-strike litho- and chemostratigraphy of the Flatreef and its footwall and hanging wall rocks, based on a diamond drill core database totalling > 720 km. At the base of the sequence intersected in the drill cores are up to 700-m-thick sills of ultramafic rocks (dunite, harzburgite, pyroxenite) emplaced into pelitic, dolomitic, and locally quartzitic and evaporitic rocks belonging to the Duitschland Formation of the Transvaal Supergroup. Next is an approximately 100-200-m sequence of low-grade-sulphide-mineralised, layered mafic-ultramafic rocks containing abundant sedimentary xenoliths and, in places, several chromite seams or stringers. This is overlain by a 100-m-thick sequence of well-mineralised mafic-ultramafic rocks (the Flatreef sensu strictu), overlain by a laterally persistent mottled compositional analogies at the base of > 1 km of homogenous Main Zone gabbronorite. Based on stratigraphic, lithological and compositional alanalogies to the layered rocks in the eastern and western Bushveld Complex, we correlate the Flatreef and its chromite bearing footwall rocks with the Upper Critical Zone, notably the interval between the UG2 chromitite and the Bastard Reef as found elsewhere in the Bushveld Complex. This includes recognition of a Merensky Reef correlative. The ultramafic rocks below the main chromitite seam (UG2 correlative

Radiochemical neutron activation analysis of high pure palladium and platinum by ion exchange chromatography

International Nuclear Information System (INIS)

Sadikov, I.I.; Zinov'ev, V.G.; Sadikova, Z.O.; Salimov, M.I.

2006-01-01

Full text: The palladium and platinum are widely used for jewel manufacture because of their beautiful white color. However the most part of these metals are widely adopted in the world as catalysts. Many works on analytical chemistry of platinum group elements published during last years are devoted to determination of platinum and palladium in other materials. There are no articles on analysis technique of the palladium and platinum purity published during last 20 years. Available publications are very old and are published till 70th of the last century, and implement chemical and spectral methods. At the same time, the palladium and platinum are very suitable for NAA. Therefore the purpose of our research was development of high-sensitivity and multielement techniques of radiochemical neutron activation analysis of a high pure palladium and platinum. Research of nuclear characteristics of palladium and platinum has shown that radioactive nuclides with different yields are formed under the reactor neutrons. 109 , 111 , 111m Pd, 109m , 111 Ag, 191 , 197 , 199 Pt, 199 Au are the most important among them. 109Pd separation factor is equal to 1*10 5 at palladium analysis, whereas 197 Pt and 199 Au separation factor is equal to 1*10 4 at the platinum analysis every other day after irradiation. Palladium and platinum can be separated by precipitation, extraction and ion exchange methods. For separation of radioactive nuclide of the matrix elements from the impurity elements we used ion exchange chromatography system Dowex-1x8 - 1 M HNO 3 for palladium and Dowex-1x8 - 0.1 M HNO 3 for platinum. At the HNO 3 acid concentrations variation from 0,1 M to 1 M more then 25 elements have distribution factors less than 1 and 10 elements have distribution factors 5 while matrix elements have distribution factors higher than 100. It allows an effective separation of these elements from palladium and platinum. Optimum sizes of the chromatographic column and the column effluent

Real life experimental determination of platinum group metals content in automotive catalytic converters

Science.gov (United States)

Yakoumis, I.; Moschovi, A. M.; Giannopoulou, I.; Panias, D.

2018-03-01

The real life experimental protocol for the preparation of spent automobile catalyst samples for elemental analysis is thoroughly described in the following study. Collection, sorting and dismantling, homogenization and sample preparation for X-Ray fluorescence spectroscopy and Atomic Adsorption Spectroscopy combined with Inductive coupled plasma mass spectrometry are discussed in detail for both ceramic and metallic spent catalysts. The concentrations of Platinum Group Metals (PGMs) in spent catalytic converters are presented based on typical consignments of recycled converters (more than 45,000 pieces) from the Greek Market. The conclusions clearly denoted commercial metallic catalytic foil contains higher PGMs loading than ceramic honeycombs. On the other hand, the total PGMs loading in spent ceramic catalytic converters has been found higher than the corresponding value for the metallic ones.

Determination of platinum group metals by ICP-AES in environmental samples after preconcentration

International Nuclear Information System (INIS)

Vlasankova, R.; Sommer, L.

1999-01-01

Platinum group metal (PGM) may have toxic properties and their presence in the environment represent danger for human health. With the introduction of automobile catalytic converters containing PGM, the emission of these noble metals into atmosphere has increased. Platinum, palladium and rhodium are used in this catalytic converters to decrease toxic emissions of carbon monoxide, unburnt hydrocarbons and nitrogen oxides in vehicles exhaust gases. These catalysts are mobile sources of PGM into the environment. Thus, increased platinum concentrations have been found in various objects of environment because of the massive introduction of such catalytic converters are present. The preconcentration and separation of PGM and their determination by ICP-AES in environmental samples are described

Investigations of radiochemical methods for the platinum group metals for NAA

International Nuclear Information System (INIS)

Tredoux, M.

A radiochemical procedure for the determination of the platinum group metals and gold is outlined in this report. The sample is irradiated, treated with acids and passed through anion-exchange columns before being determined by gamma spectrometry

Platinum stable isotopes in ferromanganese crust and nodules

Science.gov (United States)

Corcoran, Loretta; Seward, Terry; Handler, Monica R.

2015-04-01

Hydrogenetic ferromanganese (Fe-Mn) crust and nodules are slow-growing chemical sediments that form by direct precipitation from seawater, resulting in a record of changing seawater chemistry. These sediments are the primary sink for platinum in the modern oxic marine environment, hosting well-documented enrichments over other platinum-group elements (PGEs): the Pt anomaly [1]. Platinum is a non-bio-essential, highly siderophile, transition metal with six stable isotopes (190Pt, 192Pt, 194Pt, 195Pt, 196Pt, and 198Pt) with several oxidation states (Pt0, Pt2+ and Pt4+). Platinum is generally considered to exist in the hydrosphere as Pt2+ although its behaviour in the marine environment is poorly constrained, and Pt4+may also be present. Variations in ocean redox state, together with changes in source fluxes to the oceans, may therefore lead to small variations (Leaching experiments conducted on platinum rich terrestrial materials underwent platinum stable isotopic measurement as an analogue for the Pt isotopic fractionation associated with continental weathering. [1] Hodge, V.F. et al. (1985) Earth and Planetary Science Letters, 72, 158-162. [2] Creech, J. et al. (2013) Journal of Analytical Atomic Spectrometry, 28. 853-865.

THE EFFECTS OF PGE1 AND INDOMETHACIN ON ORTHODONTIC TOOTH MOVEMENT IN RAT

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EA. Niaki

1999-09-01

Full Text Available  Prostaglandin £j (PGE-^ and indomethacin, a nonstroidal antiinflammatory drug, were separately administered during ortliodontic tooth movement in rats. At the beginning, an orthodontic appliance was placed and activated in male albinos rats. In tlie first examination, the experimental group received submucosal injections of PGE-y (10 mg/kg/day near the first maxillary riglit molars, and alcohol was injected to control group animals as a vehicle similarly. Jn the second examination, indomethacin (10 mg/kg/day and metiiyl cellulose subcutaneousfy injected to experimental and control groups respectively. Tooth movement was measured at 1,3,5,7,9 and 11 days. In PGE^ group, tooth movement increased significantly at the beginning of seven days as compared to the vehicle injected group and the number of osteoclast and Howship's lacunae were markedly increased. A significant iniiibition of tooth movement occurred beginning at seven days in the indomethacin group compared to the control group.

Roadside Accumulation of Pt, Pd, Rh and Other Trace Elements From Automobiles: Catalytic Converter Attrition and Platinum-Group Element Mobility in the Roadside Environment.

Science.gov (United States)

Ely, J. C.; Dahlheimer, S. R.; Neal, C. R.

2003-12-01

Elemental abundances of Pt, Pd and Rh have been documented across the industrialized world in roadside environments due to attrition of automotive catalytic converters (Zereini and Alt, 2000, Anthropogenic PGE Emissions, Springer, 308pp; Ely et al., 2001, EnvSci&Tech, 35:3816-3822; Whiteley and Murray, 2003, SciTotEnv, in press). In our ongoing study, the highest reported roadside Pt abundance 1.8 ppm has been found immediately adjacent to the road at a field site in South Bend, IN, USA. Furthermore, initial studies show positive correlations of Pt, Pd and Rh with some trace elements (Ni, Cu, Zn and Pb), which has been confirmed by further analysis for these and other elements (Ce, Cr). It has been demonstrated that elements such as Ce are present in catalytic converters at concentrations of 100's ppm to 3-wt.%. These elements are also being attrited with Pt, Pd and Rh and aerially transported and deposited. Our field site was established next to US-933 adjacent to the Notre Dame campus. Areas were cleared of the top 2-4 cm of soil (removing surficial Pt, Pd and Rh) at 1, 5, 10 and 50 meters from the roadside. Within 3 months the 1-meter site contained 67% of the initial Rh and Pt concentrations and 100% of the initial Pd concentration. The sites at 5, 10 and 50 meters showed similar results, in some cases exceeding the initial concentrations. After 6 months the concentrations of Pt, Pd and Rh were all within error of the initial concentrations, indicating steady state abundances had probably been reached. Grass samples from each site showed that washed vs. unwashed samples were within error of each other, and there may be a slight enrichment (approx. 1 ppb) in the grasses of Pd and Pt, but this enrichment was independent of distance from the road. The steady-state situation suggests that the PGEs are being removed from the immediate roadside environment, which requires that the metals are being oxidized and/or complexed in such a way to facilitate transport. The

Determination of geochemical distribution of platinum elements in chromites and related minerals using neutron activation analysis technique

International Nuclear Information System (INIS)

Agiorgitis, G.

1978-08-01

Results of Pt, Pd, Ir, Os and Ru determination in various rocks and minerals using radiochemical neutron activation method are presented and geochemical correlations of the platinum elements studied. The method of analysis was described in detail in 4 progress reports

Effect of Platinum Group Metal Doping in Magnesium Diboride Wires

DEFF Research Database (Denmark)

Grivel, Jean-Claude; Alexiou, Aikaterini; Namazkar, Shahla

2016-01-01

The effect of some platinum group metals(PGM = Rh, Pd, and Pt) on the microstructure and critical current density of Cu/Nb-sheathed MgB2 wires has been studied using Mg1-x PGMxB2 powders with low doping levels. It was found that Pt and Pd do not enter the MgB2 lattice and have only limited influe...

A rapid and practical strategy for the determination of platinum, palladium, ruthenium, rhodium, iridium and gold in large amounts of ultrabasic rock by inductively coupled plasma optical emission spectrometry combined with ultrasound extraction

Science.gov (United States)

Zhang, Gai; Tian, Min

2015-04-01

This proposed method regulated the determination of platinum, palladium, ruthenium, rhodium, iridium and gold in platinum-group ores by nickel sulfide fire assay—inductively coupled plasma optical emission spectrometry (ICP-OES) combined with ultrasound extraction for the first time. The quantitative limits were 0.013-0.023μg/g. The samples were fused to separate the platinum-group elements from matrix. The nickel sulfide button was then dissolved with hydrochloric acid and the insoluble platinum-group sulfide residue was dissolved with aqua regia by ultrasound bath and finally determined by ICP-OES. The proposed method has been applied into the determination of platinum-group element and gold in large amounts of ultrabasic rocks from the Great Dyke of Zimbabwe.

NanoSIMS multi-element imaging reveals internalisation and nucleolar targeting for a highly-charged polynuclear platinum compound.

Science.gov (United States)

Wedlock, Louise E; Kilburn, Matt R; Liu, Rong; Shaw, Jeremy A; Berners-Price, Susan J; Farrell, Nicholas P

2013-08-11

Simultaneous multi-element imaging using NanoSIMS (nano-scale secondary ion mass spectrometry), exploiting the novel combination of (195)Pt and (15)N in platinum-am(m)ine antitumour drugs, provides information on the internalisation and subcellular localisation of both metal and ligands, and allows identification of ligand exchange.

Platinum stable isotope analysis of geological standard reference materials by double-spike MC-ICPMS.

Science.gov (United States)

Creech, J B; Baker, J A; Handler, M R; Bizzarro, M

2014-01-10

We report a method for the chemical purification of Pt from geological materials by ion-exchange chromatography for subsequent Pt stable isotope analysis by multiple-collector inductively coupled plasma mass spectrometry (MC-ICPMS) using a 196 Pt- 198 Pt double-spike to correct for instrumental mass bias. Double-spiking of samples was carried out prior to digestion and chemical separation to correct for any mass-dependent fractionation that may occur due to incomplete recovery of Pt. Samples were digested using a NiS fire assay method, which pre-concentrates Pt into a metallic bead that is readily dissolved in acid in preparation for anion-exchange chemistry. Pt was recovered from anion-exchange resin in concentrated HNO 3 acid after elution of matrix elements, including the other platinum group elements (PGE), in dilute HCl and HNO 3 acids. The separation method has been calibrated using a precious metal standard solution doped with a range of synthetic matrices and results in Pt yields of ≥90% with purity of ≥95%. Using this chemical separation technique, we have separated Pt from 11 international geological standard reference materials comprising of PGE ores, mantle rocks, igneous rocks and one sample from the Cretaceous-Paleogene boundary layer. Pt concentrations in these samples range from ca. 5 ng g -1 to 4 μg g -1 . This analytical method has been shown to have an external reproducibility on δ 198 Pt (permil difference in the 198 Pt/ 194 Pt ratio from the IRMM-010 standard) of ±0.040 (2 sd) on Pt solution standards (Creech et al., 2013, J. Anal. At. Spectrom. 28, 853-865). The reproducibility in natural samples is evaluated by processing multiple replicates of four standard reference materials, and is conservatively taken to be ca. ±0.088 (2 sd). Pt stable isotope data for the full set of reference materials have a range of δ 198 Pt values with offsets of up to 0.4‰ from the IRMM-010 standard, which are readily resolved with this technique. These

MnFe(PGe) compounds: Preparation, structural evolution, and magnetocaloric effects

International Nuclear Information System (INIS)

Yue Ming; Zhang Hong-Guo; Zhang Jiu-Xing; Liu Dan-Min

2015-01-01

The interdependences of preparation conditions, magnetic and crystal structures, and magnetocaloric effects (MCE) of the MnFePGe-based compounds are reviewed. Based upon those findings, a new method for the evaluation of the MCE in these compounds, based on differential scanning calorimetry (DSC), is proposed. The MnFePGe-based compounds are a group of magnetic refrigerants with giant magnetocaloric effect (GMCE), and as such, have drawn tremendous attention, especially due to their many advantages for practical applications. Structural evolution and phase transformation in the compounds as functions of temperature, pressure, and magnetic field are reported. Influences of preparation conditions upon the homogeneity of the compounds’ chemical composition and microstructure, both of which play a key role in the MCE and thermal hysteresis of the compounds, are introduced. Lastly, the origin of the “virgin effect” in the MnFePGe-based compounds is discussed. (paper)

TP53 status and taxane-platinum versus platinum-based therapy in ovarian cancer patients: A non-randomized retrospective study

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Markowska Janina

2008-01-01

Full Text Available Abstract Background Taxane-platinum therapy (TP has replaced platinum-based therapy (PC or PAC, DNA damaging chemotherapy in the postoperative treatment of ovarian cancer patients; however, it is not always effective. TP53 protein plays a differential role in response to DNA-damaging agents and taxanes. We sought to define profiles of patients who benefit the most from TP and also of those who can be treated with PC. Methods We compared the effectiveness of PC/PAC (n = 253 and TP (n = 199 with respect to tumor TP53 accumulation in ovarian cancer patients with FIGO stage IIB-IV disease; this was a non-randomized retrospective study. Immunohistochemical analysis was performed on 452 archival tumors; univariate and multivariate analysis by the Cox's and logistic regression models was performed in all patients and in subgroups with [TP53(+] and without TP53 accumulation [TP53(-]. Results The advantage of taxane-platinum therapy over platinum-based therapy was seen in the TP53(+, and not in the TP53(- group. In the TP53(+ group taxane-platinum therapy enhanced the probability of complete remission (p = .018, platinum sensitivity (p = .014, platinum highly sensitive response (p = .038 and longer survival (OS, p = .008. Poor tumor differentiation diminished the advantage from taxane-platinum therapy in the TP53(+ group. In the TP53(- group PC/PAC was at least equally efficient as taxane-platinum therapy and it enhanced the chance of platinum highly sensitive response (p = .010. However, in the TP53(- group taxane-platinum therapy possibly diminished the risk of death in patients over 53 yrs (p = .077. Among factors that positively interacted with taxane-platinum therapy in some analyses were endometrioid and clear cell type, FIGO III stage, bulky residual tumor, more advanced age of patient and moderate tumor differentiation. Conclusion Our results suggest that taxane-platinum therapy is particularly justified in patients with TP53(+ tumors or older

The unit group of group algebra $F_qSL(2;Z_3$

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Swati Maheshwari

2016-01-01

Full Text Available Let $\\F_q$ be a finite field of characteristic $p$ having $q$ elements, where $q = p^k$ and $p\\ge 5$. Let $ SL(2,\\Z_3$ be the special linear group of $2\\times2$ matrices with determinant $1$ over $\\Z_3$. In this note we establish the structure of the unit group of $\\F_q SL(2,\\Z_3$.

Teaching - methodical and research center of hydrogen power engineering and platinum group metals in the former Soviet Union countries

International Nuclear Information System (INIS)

Evdokimov, A.A; Sigov, A.S; Shinkarenko, V.V.

2005-01-01

Full text: Teaching - Methodical and Research Center (TMRC) 'Sokolinaja Gora' is founded in order to provide methodical-information and scientific support of institutes of higher education in the field of hydrogen power engineering and platinum group metals in Russia and in the countries of the Former Soviet union. It is independent association of creative communities of scientist of higher educational specialists. The main directions of the Center activity are: 1. Teaching-methodological support and development of teaching in the field of hydrogen power engineering and platinum group metals in Russia in the countries of the Former Soviet Union. Themes of teaching includes the basic of safe using of hydrogen technologies and devices, ecological, economic and law aspects of new hydrogen power engineering, transition to which in 21 century is one of the central problems of mankind survival; 2. Organizing of joint researches by independent creative communities of scientists in the field of hydrogen power engineering and platinum group metal; 3. Independent scientific examination, which is made by Advisory Committee of High Technologies consisting of representatives of the countries of Former Soviet Union, which are standing participants of an Annual International Symposia 'Hydrogen Power Engineering and Platinum Group Metals in the Former Soviet Union Countries'. Structure of the Center: 1. Center of strategic development in the field of high technologies; 2. Scientific Research Institute of Hydrogen Power Engineering and Platinum Group Metals; 3. Teaching-Methodical Association in specialization 'Hydrogen Power Engineering and economics' and hydrogen wide spread training; 4. Media Center 'Hydrogen Power Engineering and Platinum Group Metals', 5. Organizational Center; 6. Administrative Center. The Center will be established step-by-step in 2005-2010 on the basis of the following programs: Teaching-methodological program. On the basis of this program it is planned to

Aspirin provocation increases 8-iso-PGE2 in exhaled breath condensate of aspirin-hypersensitive asthmatics.

Science.gov (United States)

Mastalerz, Lucyna; Januszek, Rafał; Kaszuba, Marek; Wójcik, Krzysztof; Celejewska-Wójcik, Natalia; Gielicz, Anna; Plutecka, Hanna; Oleś, Krzysztof; Stręk, Paweł; Sanak, Marek

2015-09-01

Isoprostanes are bioactive compounds formed by non-enzymatic oxidation of polyunsaturated fatty acids, mostly arachidonic, and markers of free radical generation during inflammation. In aspirin exacerbated respiratory disease (AERD), asthmatic symptoms are precipitated by ingestion of non-steroid anti-inflammatory drugs capable for pharmacologic inhibition of cyclooxygenase-1 isoenzyme. We investigated whether aspirin-provoked bronchoconstriction is accompanied by changes of isoprostanes in exhaled breath condensate (EBC). EBC was collected from 28 AERD subjects and 25 aspirin-tolerant asthmatics before and after inhalatory aspirin challenge. Concentrations of 8-iso-PGF2α, 8-iso-PGE2, and prostaglandin E2 were measured using gas chromatography/mass spectrometry. Leukotriene E4 was measured by immunoassay in urine samples collected before and after the challenge. Before the challenge, exhaled 8-iso-PGF2α, 8-iso-PGE2, and PGE2 levels did not differ between the study groups. 8-iso-PGE2 level increased in AERD group only (p=0.014) as a result of the aspirin challenge. Urinary LTE4 was elevated in AERD, both in baseline and post-challenge samples. Post-challenge airways 8-iso-PGE2 correlated positively with urinary LTE4 level (p=0.046), whereas it correlated negatively with the provocative dose of aspirin (p=0.027). A significant increase of exhaled 8-iso-PGE2 after inhalatory challenge with aspirin was selective and not present for the other isoprostane measured. This is a novel finding in AERD, suggesting that inhibition of cyclooxygenase may elicit 8-iso-PGE2 production in a specific mechanism, contributing to bronchoconstriction and systemic overproduction of cysteinyl leukotrienes. Copyright © 2015 Elsevier Inc. All rights reserved.

The determination, by atomic-absorption spectrophotometry using electrothermal atomization, of platinum, palladium, rhodium, ruthenium, and iridium

International Nuclear Information System (INIS)

Haines, J.; Robert, R.V.D.

1982-01-01

A method that involves measurement by atomic-absorption spectrophotometry using electrothermal atomization has been developed for the determination of trace quantities of platinum, palladium, rhodium, ruthenium, and iridium in mineralogical samples. The elements are separated and concentrated by fusion, nickel sulphide being used as the collector, and the analyte elements are measured in the resulting acid solution. An organic extraction procedure was found to offer no advantages over the proposed method. Mutual interferences between the five platinum-group metals examined, as well as interferences from gold, silver, and nickel were determined. The accuracy of the measurement was established by the analysis of a platinum-ore reference material. The lower limits of determination of each of the analyte elements in a sample material are as follows: platinum 1,6μg/l, palladium 0,2μg/1, rhodium 0,5μg/l, ruthenium 3μg/l, and iridium 2,5μg/l. The relative standard deviations range from 0,05 for rhodium to 0.08 for iridium. The method, which is described in detail in the Appendix, is applicable to the determination of these elements in ores, tailings, and geological materials in which the total concentration of the noble metals is less than 1g/t

PG&E WaveConnect Program Final Report

Energy Technology Data Exchange (ETDEWEB)

Brendan P. Dooher; Edward Cheslak; Robert Booth; Doug Davy; Annette Faraglia; Ian Caliendo; Gina Morimoto; Douglas Herman

2011-12-01

The PG&E WaveConnect project was intended to demonstrate the technical and economic viability of wave power in the open ocean adjacent to PG&E's service territory. WaveConnect was conceived as a multi-stage development process leading to long-term megawatt-scale wave power production. The first-stage tasks consisted of site selection, permitting, pilot plant design, and assessment of technology and commercial readiness. The second stage would have included development of infrastructure, undersea cabling, and deployment of wave energy conversion devices (WECs). In the third stage, the most promising WEC devices would have been deployed in larger quantities and connected to the grid. This report documents the findings of Stage One. Site Selection: After studying the wave energy potential, grid interconnection and other project infrastructure along the California coast, PG&E selected two sites: one near Eureka, called the Humboldt WaveConnect (HWC) project, and another near Vandenberg Air Force Base, called the Central Coast WaveConnect project (CCWC). Permitting: FERC issued PG&E preliminary permits for HWC in 2008 and for CCWC in 2010. PG&E chose to use FERC's Pilot Project Licensing Process, which was intended to streamline licensing to allow relatively quick and easy installation, operation, and environmental testing for pilot projects. Permitting, however, proved to be complicated, time-consuming and expensive, mainly because of the uncertain impacts of WEC devices. PG&E learned that even under the PPLP the project would still require a full analysis under CEQA, including an EIR, as well as Monitoring and Adaptive Management Programs and other requirements that had significant cost and scheduling implications. A majority of efforts were expended on permitting activities. Pilot Plant Design: PG&E prepared a conceptual design for a 5-MW pilot test facility at the Humboldt site, which consisted of an off-shore deployment area where WECs of different

Palladium, platinum, and rhodium contents of rocks near the lower margin of the Stillwater complex, Montana.

Science.gov (United States)

Zientek, M.L.; Foose, M.P.; Leung, Mei

1986-01-01

Statistical summaries are reported for Pd, Pt and Rh contents of rocks from the lower part of the Stillwater complex, the underlying contact-metamorphosed sediments, and post-metamorphic dykes and sills wholly within the hornfelses. Variability of the data among the rock types is attributed largely to differences in sulphide content. Non-correlation of sulphur with platinum-group assays of many rock types leads to the suggestion that the immiscible sulphide and silicate liquids did not completely equilibrate with respect to platinum-group elements. -G.J.N.

Growth and adherence of Staphylococcus aureus were enhanced through the PGE2 produced by the activated COX-2/PGE2 pathway of infected oral epithelial cells.

Directory of Open Access Journals (Sweden)

Yuxia Wang

Full Text Available Staphylococcus aureus is a major pathogen of varieties of oral mucous infection. Prostaglandin E2 (PGE2 is a pro-inflammatory factor and Cyclooxygenase 2 (COX-2 is a critical enzyme of PGE2 biosynthesis. The purpose of this study is to investigate whether Staphylococcus aureus can increase PGE2 production of oral epithelial cells and how PGE2 functions in the growth and adherence of Staphylococcus aureus. mRNA levels of COX-2, fnbpA and fnbpB were estimated by quantitative PCR. PGE2 production was measured by Enzyme Linked Immunosorbent Assay (ELISA. The binding biomass of Staphylococcus aureus to human fibronectin was investigated by crystal violet staining and confocal laser scanning microscopy and the adherent force was measured by atomic force microscope (AFM. The COX-2 mRNA level and PGE2 production were increased by Staphylococcus aureus. PGE2 promoted the growth and biofilm formation of Staphylococcus aureus, enhanced the attachment of Staphylococcus aureus to the human fibronectin as well as to the HOK cells. The transcription of fnbpB was up-regulated by PGE2 in both early and middle exponential phase but not fnbpA. These results suggest that the activation of COX-2/PGE2 pathway in oral epithelial cell by Staphylococcus aureus can in turn facilitate the growth and the ability to adhere of the pathogen. These findings uncover a new function of PGE2 and may lead to the potential of COX-2/PGE2 targeting in the therapy of inflammation and cancer in both which the COX-2/PGE2 pathway were observed activated.

Effects of balneotherapy on serum IL-1, PGE2 and LTB4 levels in fibromyalgia patients.

Science.gov (United States)

Ardiç, Füsum; Ozgen, Merih; Aybek, Hülya; Rota, Simin; Cubukçu, Duygu; Gökgöz, Ali

2007-03-01

The purpose of this study was to investigate the clinical effects of balneotherapy in the treatment of Fibromyalgia Syndrome (FMS) and to determine if balneotherapy influences serum levels of inflammation markers, IL-1, PGE2 and LTB4. 24 primary fibromyalgia female patients diagnosed according to American College of Rheumatology criteria were included to the study. Their ages ranged between 33 and 55 years. FMS patients were randomly assigned in two groups as, group 1 (n = 12) and group 2 (n = 12). Group 1 received 20-min bathing, once in a day for five days per week. Patients participated in the study for 3 weeks (total of 15 sessions) in Denizli. Group 2 did not receive balneotherapy. FMS patients were evaluated by tenderness measurements (tender point count and algometry), Visual Analogue Scale, Beck's Depression Index, Fibromyalgia Impact Questionnaire. Ten healthy women recruited group three as the controls. Serum PGE2, LTB4 and IL1-alpha levels were measured in all three groups. The biochemical measurements and clinical assessments were performed before and at the end of general period of therapy. Statistically significant alterations in algometric score, Visual Analogue score, Beck's Depression Index and PGE2 levels (P balneotherapy between group 1 and 2. Mean PGE2 level of FMS patients were higher compared to healthy control group (P balneotherapy IL-1 and LTB4 significantly decreased in group 1 (P balneotherapy is an effective choice of treatment in patients with FMS relieving the clinical symptoms, and possibly influencing the inflammatory mediators.

Contamination from gold and platinum-group metals mining in the Gulf of Darién, Colombia

Science.gov (United States)

Vasquez-Bedoya, L.; Palacio Baena, J.

2013-12-01

Gulf of Darién, triangular southernmost extension of the Caribbean Sea, bounded by Panama on the southwest and by Colombia on the southeast and east. The Gulf is made up of 17 municipalities in the department of Choco and Antioquia. The Gulf of Darién is a geostrategic region, rich in biodiversity, known for its natural resources of minerals, oil, lumber as well as its water and fertile land. The Darién also acts as the bridge between South America and Central America and has access to the Pacific Ocean and the Caribbean Sea. The economy in the region is based mainly on agribusinesses, tourism and mining activities, mainly the 'mining of gold and platinum-group metals'. In our study we determined the degree of trace element contamination in estuarine sediment samples originated from mining activities and municipal waste water discharges of effluents on the gulf of Darién. . Surface samples were taken from 17 locations through the entire Gulf. Grain size, Corg, Ag, Al, Ca , Cr, Cu, Fe, Mg, Mn, Na, Ni, Pb and Zn concentrations were analyzed, and enrichment factors (EF) as well as geo-accumulation indices (Igeo) were calculated. Concentrations of Pb, Zn, Ni, Cu and Cr show levels that are consistent with those typically found in urbanized marine environments. EF and Igeo values revealed that the Gulf is extremely contaminated with Ag and moderately contaminated with Cr and Zn. The sources of Cr, Ag, Hg and Zn are associated with the development of mining activities in the Atrato River basin. The observed enrichment of Ag may be explained as a residue of the extraction of gold and platinum-group metals.

The Dovyren Intrusive Complex (Southern Siberia, Russia): Insights into dynamics of an open magma chamber with implications for parental magma origin, composition, and Cu-Ni-PGE fertility

Science.gov (United States)

Ariskin, Alexey; Danyushevsky, Leonid; Nikolaev, Georgy; Kislov, Evgeny; Fiorentini, Marco; McNeill, Andrew; Kostitsyn, Yuri; Goemann, Karsten; Feig, Sandrin T.; Malyshev, Alexey

2018-03-01

The Dovyren Intrusive Complex (DIC, Northern Baikal region, 728 Ma) includes the layered dunite-troctolite-gabbronorite Yoko-Dovyren massif (YDM), associated mafic-ultramafic sills, and dykes of olivine-rich to olivine-free gabbronorite. Major rock types of the DIC are presented, including a diversity of olivine orthocumulates to olivine-plagioclase and gabbroic adcumulates, carbonate-contaminated ultramafics and Cu-Ni-PGE mineralisation. Detailed comparisons of complete cross-sections of the YDM in its centre and at the NE and SW margins demonstrate differences in the cumulate succession, mineral chemistry, and geochemical structure that likely reflect variations in parental magma compositions. Combining petrochemical reconstructions for most primitive rocks and calculations using the COMAGMAT-5 model, it is shown that the central and peripheral parts of the intrusion formed by olivine-laden parental magmas ranged in their temperatures by 100 °C, approximately from 1290 °C ( 11 wt% MgO, olivine Fo88) to 1190 °C ( 8 wt% MgO, olivine Fo86). Thermodynamic modelling suggests that the most primitive high-Mg magma was S-undersaturated, whereas its derivatives became S-saturated at T piles to generate poorly-mineralised plagiodunite. In the troctolite and gabbroic parts of the Dovyren chamber, sulphide immiscibility likely occurred at lower temperatures, producing Cu-rich sulphide precursors, which gave rise to the 'platinum group mineral' (PGM-containing) troctolite and low-mineralised PGE-rich anorthosite in the Main Reef. The geochemical structure of the YDM demonstrates C-shaped distributions of TiO2, K2O, P2O5, and incompatible trace elements, which are 3-5 fold depleted in the cumulate rocks from the inner horizons of the intrusion with respect to the relatively thin lower and upper contact zones. In addition, a marked misbalance between estimates of the average composition of the YDM and that of the proposed olivine-laden parental magmas is established. This

Magma Fertility is the First-Order Factor for the Formation of Porphyry Cu±Au Deposits

Science.gov (United States)

Park, J. W.; Campbell, I. H.; Malaviarachchi, S. P. K.; Cocker, H.; Nakamura, E.; Kay, S. M.

2017-12-01

Magma fertility, the metal abundance in magma, has been considered to be one of the key factors for the formation of porphyry Cu±Au deposits. In this study we provide clear evidence to support the hypothesis that the platinum group element (PGE) can be used to distinguish barren from ore-bearing Cu±Au felsic suites. We determined the PGE contents of three barren volcanic and subvolcanic suites from Argentina and Japan, and compare the results with two porphyry Cu-bearing subvolcanic suites from Chile and two porphyry Cu-Au-bearing suites from Australia. The barren suites are significantly depleted in PGE abundances by the time of fluid exsolution, which is attributed to early sulfide saturation at mid to lower crust depths or assimilation of chalcophile element-poor crustal materials. Barren magma, produced by melting continental crust, may have been initially deficient in chalcophile elements. In contrast, the Cu±Au ore-bearing suites contain at least an order of magnitude higher PGE contents than those of the barren suites by the time of fluid saturation. They are characterized by late sulfide saturation in a shallow magma chamber, which allows the chalcophile elements to concentrate in the fractionating magma from which they are sequestered by ore-forming fluids. We suggest the Pd/MgO and Pd/Pt ratios of igneous rocks can be used as magma fertility indicators, and to distinguish between barren, porphyry Cu and porphyry Cu-Au magmatic systems.

High pressure stability of the monosilicides of cobalt and the platinum group elements

International Nuclear Information System (INIS)

Hernandez, J.A.; Vočadlo, L.; Wood, I.G.

2015-01-01

Highlights: • We model the high-pressure phases of cobalt- and platinum-group-monosilicides. • CoSi, RuSi, OsSi transform with pressure from the ε-FeSi to the CsCl structure. • RhSi and IrSi transform with pressure from the MnP structure to the ε-FeSi structure. • PdSi and PtSi transform with pressure from the MnP structure to the CuTi structure. - Abstract: The high pressure stability of CoSi, RuSi, RhSi, PdSi, OsSi, IrSi and PtSi was investigated by static first-principles calculations up to 300 GPa at 0 K. As found experimentally, at atmospheric pressure, CoSi, RuSi and OsSi were found to adopt the cubic ε-FeSi structure (P2 1 3) whereas RhSi, PdSi, IrSi and PtSi were found to adopt the orthorhombic MnP (Pnma) structure. At high pressure, CoSi, RuSi and OsSi show a phase transition to the CsCl structure (Pm3 ¯ m) structure at 270 GPa, 7 GPa and 6 GPa respectively. RhSi and IrSi were found to transform to an ε-FeSi structure at 10 GPa and 25 GPa. For PdSi and PtSi, a transformation from the MnP structure to the tetragonal CuTi structure (P4/nmm) occurs at 13 GPa and 20 GPa. The pressure dependence of the electronic density of states reveals that RuSi and OsSi are semiconductors in the ε-FeSi structure and become metallic in the CsCl structure. RhSi and IrSi are metals in the MnP structure and become semimetals in their high pressure ε-FeSi form. CoSi in the ε-FeSi configuration is a semimetal. PdSi and PtSi remain metallic throughout up to 300 GPa

Platinum-Resistor Differential Temperature Sensor

Science.gov (United States)

Kolbly, R. B.; Britcliffe, M. J.

1985-01-01

Platinum resistance elements used in bridge circuit for measuring temperature difference between two flowing liquids. Temperature errors with circuit are less than 0.01 degrees C over range of 100 degrees C.

The effect of watermelon frost on prostaglandin E2 (PGE2 in inflamed pulp tissue (in vitro study

Directory of Open Access Journals (Sweden)

Dennis Dennis

2009-06-01

Full Text Available Background: Pulp inflammation can be marked by the increase of prostaglandin E2(PGE2 level compared to normal pulp. The increase of PGE2 may lead to vasodilatation, increase of vascular permeability, pain and bone resorption. Watermelon frost has been well known in Chinese society for pain relief and inflammation in oral cavity and teeth. Purpose: The aim of this study was to investigate that watermelon frost can be used to decrease the PGE2 level. Method: 27 samples of pulp tissues used in this in-vitro study, were extirpated from the patients’ teeth with symptomatic irreversible pulpitis referred to clinic of Conservative Dentistry, RSPGM Faculty of Dentistry, USU. Trial materials were applied to 27 samples i.e. watermelon frost as a trial material and commercial watermelon frost and eugenol to observe their effect on PGE2. PGE2 level of each material was detected through ELISA method by measuring and comparing the absorbance reading of the wells of the samples against standards with a micro plate reader at W1 = 650 nm and W2 = 490 nm. Result: The result showed the biggest effect was found in the third group (eugenol, mean 4.6933, followed by the first group (watermelon frost as a trial material, mean 18,1578 then the second group (commercial watermelon frost, mean 82,2689. OneWay ANOVA revealed that there were significant differences among all trial materials (p < 0.001 on PGE2 level. Conclusion: This study demonstrated that watermelon frost can be used to decrease the PGE2 level in inflamed pulp tissue and led to the acceptance of traditional medicine and natural products as an alternative form of dental care.

Micro-SR-XRF and micro-PIXE studies for archaeological gold identification - The case of Carpathian (Transylvanian) gold and of Dacian bracelets

International Nuclear Information System (INIS)

Constantinescu, B.; Bugoi, R.; Cojocaru, V.; Radtke, M.; Calligaro, T.; Salomon, J.; Pichon, L.; Roehrs, S.; Ceccato, D.; Oberlaender-Tarnoveanu, E.

2008-01-01

Trace-elements are more significant for provenancing archaeological metallic artifacts than the main components. For gold, the most promising elements are platinum group elements (PGE), Sn, Te, Sb, Hg and Pb. Several small fragments of natural Transylvanian gold - placer and primary - were studied by using micro-PIXE technique at the Legnaro National Laboratory AN2000 microbeam facility, Italy and at the AGLAE accelerator, C2RMF, Paris, France and by using micro synchrotron radiation X-ray fluorescence (micro-SR-XRF) at BESSY synchrotron, Berlin, Germany. The goal of the study was to identify the trace-elements, especially Sn, Sb and Te. A spectacular application to five Dacian gold bracelets authentication is presented (Sn and Sb traces)

Urinary excretion of platinum, arsenic and selenium of cancer patients from the Antofagasta region in Chile treated with platinum-based drugs

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Román Domingo A

2012-04-01

Full Text Available Abstract Background Arsenic exposure increases the risk of non-cancerous and cancerous diseases. In the Antofagasta region in Chile, an established relationship exists between arsenic exposure and the risk of cancer of the bladder, lung and skin. Platinum-based drugs are first-line treatments, and many works recognise selenium as a cancer-fighting nutrient. We characterised the short-term urinary excretion amounts of arsenic, selenium and platinum in 24-h urine samples from patients with lung cancer and those with cancer other than lung treated with cisplatin or/and carboplatin. As - Se - Pt inter-element relationships were also investigated. Results The amounts of platinum excreted in urine were not significantly different between patients with lung cancer and those with other cancers treated with cisplatin, despite the significant variation in platinum amounts supplied from platinum-based drugs. In general, the analytical amounts of excreted selenium were greater than those for arsenic, which could imply that platinum favours the excretion of selenium. For other types of cancers treated with drugs without platinum, excretion of selenium was also greater than that of arsenic, suggesting an antagonist selenium-anti-cancer drug relationship. Conclusions Regards the baseline status of patients, the analytical amounts of excreted Se is greater than those for As, particularly, for cisplatin chemotherapy. This finding could imply that for over the As displacement Pt favours the excretion of Se. The analytical amounts of excreted Se were greater than those for As, either with and without Pt-containing drugs, suggesting an antagonist Se-anti-cancer drug relationship. However, it seemed that differences existed between As - Se - Pt inter-element associations in patients treated for lung cancer in comparison with those treated for cancer other than lung. Therefore, knowledge obtained in this work, can contribute to understanding the arsenic cancer

Increase in intracellular PGE2 induces apoptosis in Bax-expressing colon cancer cell

International Nuclear Information System (INIS)

Lalier, Lisenn; Pedelaborde, François; Braud, Christophe; Menanteau, Jean; M Vallette, François; Olivier, Christophe

2011-01-01

NSAIDs exhibit protective properties towards some cancers, especially colon cancer. Yet, it is not clear how they play their protective role. PGE 2 is generally shown as the only target of the NSAIDs anticancerous activity. However, PGE 2 known targets become more and more manifold, considering both the molecular pathways involved and the target cells in the tumour. The role of PGE 2 in tumour progression thus appears complex and multipurpose. To gain understanding into the role of PGE 2 in colon cancer, we focused on the activity of PGE 2 in apoptosis in colon cancer cell lines. We observed that an increase in intracellular PGE 2 induced an apoptotic cell death, which was dependent on the expression of the proapoptotic protein Bax. This increase was induced by increasing PGE 2 intracellular concentration, either by PGE 2 microinjection or by the pharmacological inhibition of PGE 2 exportation and enzymatic degradation. We present here a new sight onto PGE 2 in colon cancer cells opening the way to a new prospective therapeutic strategy in cancer, alternative to NSAIDs

PGE2-induced colon cancer growth is mediated by mTORC1

International Nuclear Information System (INIS)

Dufour, Marc; Faes, Seraina; Dormond-Meuwly, Anne; Demartines, Nicolas; Dormond, Olivier

2014-01-01

Highlights: • PGE 2 activates mTORC1 in colon cancer cells. • Inhibition of mTORC1 blocks PGE 2 induced colon cancer cell growth. • mTORC1 is a signaling intermediary in PGE 2 induced colon cancer cell responses. - Abstract: The inflammatory prostaglandin E 2 (PGE 2 ) cytokine plays a key role in the development of colon cancer. Several studies have shown that PGE 2 directly induces the growth of colon cancer cells and furthermore promotes tumor angiogenesis by increasing the production of the vascular endothelial growth factor (VEGF). The signaling intermediaries implicated in these processes have however not been fully characterized. In this report, we show that the mechanistic target of rapamycin complex 1 (mTORC1) plays an important role in PGE 2 -induced colon cancer cell responses. Indeed, stimulation of LS174T cells with PGE 2 increased mTORC1 activity as observed by the augmentation of S6 ribosomal protein phosphorylation, a downstream effector of mTORC1. The PGE 2 EP 4 receptor was responsible for transducing the signal to mTORC1. Moreover, PGE 2 increased colon cancer cell proliferation as well as the growth of colon cancer cell colonies grown in matrigel and blocking mTORC1 by rapamycin or ATP-competitive inhibitors of mTOR abrogated these effects. Similarly, the inhibition of mTORC1 by downregulation of its component raptor using RNA interference blocked PGE 2 -induced LS174T cell growth. Finally, stimulation of LS174T cells with PGE 2 increased VEGF production which was also prevented by mTORC1 inhibition. Taken together, these results show that mTORC1 is an important signaling intermediary in PGE 2 mediated colon cancer cell growth and VEGF production. They further support a role for mTORC1 in inflammation induced tumor growth

Creatine supplementation reduces plasma levels of pro-inflammatory cytokines and PGE2 after a half-ironman competition.

Science.gov (United States)

Bassit, R A; Curi, R; Costa Rosa, L F B P

2008-08-01

The effect of creatine supplementation upon plasma levels of pro-inflammatory cytokines: Interleukin (IL) 1 beta and IL-6, Tumor Necrosis Factor alpha (TNFalpha), and Interferon alpha (INF alpha) and Prostaglandin E(2) (PGE(2)) after a half-ironman competition were investigated. Eleven triathletes, each with at least three years experience of participation in this sport were randomly divided between the control and experimental groups. During 5 days prior to competition, the control group (n = 6) was supplemented with carbohydrate (20 g x d(-1)) whereas the experimental group (n = 5) received creatine (20 g x d(-1)) in a double-blind trial. Blood samples were collected 48 h before and 24 and 48 h after competition and were used for the measurement of cytokines and PGE(2). Forty-eight hours prior to competition there was no difference between groups in the plasma concentrations (pg x ml(-1), mean +/- SEM) of IL-6 (7.08 +/- 0.63), TNFalpha (76.50 +/- 5.60), INF alpha (18.32 +/- 1.20), IL-1 beta (23.42 +/- 5.52), and PGE(2) (39.71 +/- 3.8). Twenty-four and 48 h after competition plasma levels of TNFalpha, INF alpha, IL-1 beta and PGE(2) were significantly increased (P long distance triathlon competition may reduce the inflammatory response induced by this form of strenuous of exercise.

PGE2, Kidney Disease, and Cardiovascular Risk: Beyond Hypertension and Diabetes

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Nasrallah, Rania; Hassouneh, Ramzi

2016-01-01

An important measure of cardiovascular health is obtained by evaluating the global cardiovascular risk, which comprises a number of factors, including hypertension and type 2 diabetes, the leading causes of illness and death in the world, as well as the metabolic syndrome. Altered immunity, inflammation, and oxidative stress underlie many of the changes associated with cardiovascular disease, diabetes, and the metabolic syndrome, and recent efforts have begun to elucidate the contribution of PGE2 in these events. This review summarizes the role of PGE2 in kidney disease outcomes that accelerate cardiovascular disease, highlights the role of cyclooxygenase-2/microsomal PGE synthase 1/PGE2 signaling in hypertension and diabetes, and outlines the contribution of PGE2 to other aspects of the metabolic syndrome, particularly abdominal adiposity, dyslipidemia, and atherogenesis. A clearer understanding of the role of PGE2 could lead to new avenues to improve therapeutic options and disease management strategies. PMID:26319242

HIGHLY REFRACTORY CRUCIBLES OF STABILIZED ZIRCONIA FOR INDUCTION MELTING OF THE PLATINUM GROUP METALS, FABRICATED BY VIBROCASTING

OpenAIRE

V. V. Primachenko; V. V. Martynenko; I. G. Szulik; I. A. Kushchenko

2012-01-01

As the result of the studies at PJSC « UKRNIIO them. A.S.Berezhnogo» the technology and commercial production of crucibles from stabilized zirconia for the smelting of platinum group metals are develop

Randomized Comparison of Isosorbide Mononitrate and PGE2 Gel for Cervical Ripening at Term including High Risk Pregnancy

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Kavita Agarwal

2014-01-01

Full Text Available Aims. Prostaglandin E2 is the most commonly used drug for cervical ripening prior to labour induction. However, there are concerns regarding uterine tachysystole and nonreassuring fetal heart (N-RFH. Isosorbide mononitrate (IMN has been used successfully for cervical ripening. The present study was conducted to compare the two drugs for cervical ripening at term in hospital. Methods. Two hundred women with term pregnancies referred for induction of labour with Bishop score less than 6 were randomly allocated to receive either 40 mg IMN tablet vaginally (n=100 or 0.5 mg PGE2 gel intracervically (n=100. Adverse effects, progress, and outcomes of labour were assessed. Results. PGE2 group had significantly higher postripening mean Bishop score, shorter time from start of medication to vaginal delivery (13.37 ± 10.67 hours versus 30.78 ± 17.29 hours, and shorter labour-delivery interval compared to IMN group (4.53 ± 3.97 hours versus 7.34 ± 5.51 hours. However, PGE2 group also had significantly higher incidence of uterine tachysystole (15% and N-RFH (11% compared to none in IMN group, as well as higher caesarean section rate (27% versus 17%. Conclusions. Cervical ripening with IMN was less effective than PGE2 but resulted in fewer adverse effects and was safer especially in high risk pregnancies.

Same-Side Platinum Electrodes for Metal Assisted Etching of Porous Silicon

Science.gov (United States)

2015-11-01

Platinum Electrodes for Metal Assisted Etching of Porous Silicon by Matthew H Ervin and Brian Isaacson Sensors and Electron Devices Directorate...SUBTITLE Same-Side Platinum Electrodes for Metal Assisted Etching of Porous Silicon 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT

HIGHLY REFRACTORY CRUCIBLES OF STABILIZED ZIRCONIA FOR INDUCTION MELTING OF THE PLATINUM GROUP METALS, FABRICATED BY VIBROCASTING

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V. V. Primachenko

2012-01-01

Full Text Available As the result of the studies at PJSC « UKRNIIO them. A.S.Berezhnogo» the technology and commercial production of crucibles from stabilized zirconia for the smelting of platinum group metals are develop

PGE{sub 2}-induced colon cancer growth is mediated by mTORC1

Energy Technology Data Exchange (ETDEWEB)

Dufour, Marc, E-mail: Marc.dufour@chuv.ch; Faes, Seraina, E-mail: Seraina.faes@chuv.ch; Dormond-Meuwly, Anne, E-mail: Anne.meuwly-Dormond@chuv.ch; Demartines, Nicolas, E-mail: Demartines@chuv.ch; Dormond, Olivier, E-mail: Olivier.dormond@chuv.ch

2014-09-05

Highlights: • PGE{sub 2} activates mTORC1 in colon cancer cells. • Inhibition of mTORC1 blocks PGE{sub 2} induced colon cancer cell growth. • mTORC1 is a signaling intermediary in PGE{sub 2} induced colon cancer cell responses. - Abstract: The inflammatory prostaglandin E{sub 2} (PGE{sub 2}) cytokine plays a key role in the development of colon cancer. Several studies have shown that PGE{sub 2} directly induces the growth of colon cancer cells and furthermore promotes tumor angiogenesis by increasing the production of the vascular endothelial growth factor (VEGF). The signaling intermediaries implicated in these processes have however not been fully characterized. In this report, we show that the mechanistic target of rapamycin complex 1 (mTORC1) plays an important role in PGE{sub 2}-induced colon cancer cell responses. Indeed, stimulation of LS174T cells with PGE{sub 2} increased mTORC1 activity as observed by the augmentation of S6 ribosomal protein phosphorylation, a downstream effector of mTORC1. The PGE{sub 2} EP{sub 4} receptor was responsible for transducing the signal to mTORC1. Moreover, PGE{sub 2} increased colon cancer cell proliferation as well as the growth of colon cancer cell colonies grown in matrigel and blocking mTORC1 by rapamycin or ATP-competitive inhibitors of mTOR abrogated these effects. Similarly, the inhibition of mTORC1 by downregulation of its component raptor using RNA interference blocked PGE{sub 2}-induced LS174T cell growth. Finally, stimulation of LS174T cells with PGE{sub 2} increased VEGF production which was also prevented by mTORC1 inhibition. Taken together, these results show that mTORC1 is an important signaling intermediary in PGE{sub 2} mediated colon cancer cell growth and VEGF production. They further support a role for mTORC1 in inflammation induced tumor growth.

Platinum recycling in the United States in 1998

Science.gov (United States)

Hilliard, Henry E.

2001-01-01

In the United States, catalytic converters are the major source of secondary platinum for recycling. Other sources of platinum scrap include reforming and chemical process catalysts. The glass industry is a small but significant source of platinum scrap. In North America, it has been estimated that in 1998 more than 20,000 kilograms per year of platinum-group metals from automobile catalysts were available for recycling. In 1998, an estimated 7,690 kilograms of platinum were recycled in the United States. U.S. recycling efficiency was calculated to have been 76 percent in 1998; the recycling rate was estimated at 16 percent.

Regional tectonics, geology, magma chamber processes and mineralisation of the Jinchuan nickel-copper-PGE deposit, Gansu Province, China: A review

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T.M. (Mike Porter

2016-05-01

The Jinchuan ultramafic intrusion was injected into three interconnected sub-chambers, each containing a separate orebody. It essentially comprises an olivine-orthopyroxene-chromite cumulate, with interstitial orthopyroxene, clinopyroxene, plagioclase and phlogopite, and is predominantly composed of lherzolite (∼80%, with an outer rim of olivine pyroxenite and cores of mineralised dunite. Mineralisation occurs as disseminated and net-textured sulphides, predominantly within the dunite, with lesser, PGE rich lenses, late massive sulphide accumulations, small copper rich pods and limited mineralised diopside skarn in wall rock marbles. The principal ore minerals are pyrrhotite (the dominant sulphide, pentlandite, chalcopyrite, cubanite, mackinawite and pyrite, with a variety of platinum group minerals and minor gold. The deposit underwent significant post-magmatic tremolite-actinolite, chlorite, serpentine and magnetite alteration. The volume of the Jinchuan intrusion accounts for <3% of the total parental magma required to generate the contained olivine and sulphide. It is postulated that mafic melt, intruded into the lower crust, hydraulically supported by density contrast buoyancy from below the Moho, ponded in a large staging chamber, where crystallisation and settling formed a lower sulphide rich mush. This mush was subsequently injected into nearby shallow dipping faults to form the Jinchuan intrusion.

Dipyrone metabolite 4-MAA induces hypothermia and inhibits PGE2 -dependent and -independent fever while 4-AA only blocks PGE2 -dependent fever.

Science.gov (United States)

Malvar, David do C; Aguiar, Fernando A; Vaz, Artur de L L; Assis, Débora C R; de Melo, Miriam C C; Jabor, Valquíria A P; Kalapothakis, Evanguedes; Ferreira, Sérgio H; Clososki, Giuliano C; de Souza, Glória E P

2014-08-01

The antipyretic and hypothermic prodrug dipyrone prevents PGE2 -dependent and -independent fever induced by LPS from Escherichia coli and Tityus serrulatus venom (Tsv) respectively. We aimed to identify the dipyrone metabolites responsible for the antipyretic and hypothermic effects. Male Wistar rats were treated i.p. with indomethacin (2 mg·kg(-1) ), dipyrone, 4-methylaminoantipyrine (4-MAA), 4-aminoantipyrine (4-AA) (60-360 mg·kg(-1) ), 4-formylaminoantipyrine, 4-acethylaminoantipyrine (120-360 mg·kg(-1) ) or vehicle 30 min before i.p. injection of LPS (50 μg·kg(-1) ), Tsv (150 μg·kg(-1) ) or saline. Rectal temperatures were measured by tele-thermometry and dipyrone metabolite concentrations determined in the plasma, CSF and hypothalamus by LC-MS/MS. PGE2 concentrations were determined in the CSF and hypothalamus by elisa. In contrast to LPS, Tsv-induced fever was not followed by increased PGE2 in the CSF or hypothalamus. The antipyretic time-course of 4-MAA and 4-AA on LPS-induced fever overlapped with the period of the highest concentrations of 4-MAA and 4-AA in the hypothalamus, CSF and plasma. These metabolites reduced LPS-induced fever and the PGE2 increase in the plasma, CSF and hypothalamus. Only 4-MAA inhibited Tsv-induced fever. The higher doses of dipyrone and 4-MAA also induced hypothermia. The presence of 4-MAA and 4-AA in the CSF and hypothalamus was associated with PGE2 synthesis inhibition and a decrease in LPS-induced fever. 4-MAA was also shown to be an antipyretic metabolite for PGE2 -independent fever induced by Tsv suggesting that it is responsible for the additional antipyretic mechanism of dipyrone. Moreover, 4-MAA is the hypothermic metabolite of dipyrone. © 2014 The British Pharmacological Society.

Osteoblast Differentiation Decreases Hypergravity-Stimulated Release of PGE(sub 2)

Science.gov (United States)

Searby, Nancy D.; Steele, Charles R.; Globus, Ruth K.

2002-01-01

We determined if progressive differentiation of osteoblasts influences their sensitivity to gravitational loading. Osteoblasts were cultured for 4 days (confluent monolayer), 6 days (prenodules), 9 days (nodules) and 19 days (mineralized nodules), then centrifuged at 10 times gravity (g) or 50-g for 3 hours using the NASA Ames 1-ft. Diameter Centrifuge. Stationary controls were placed in an adjacent incubator. Following centrifugation, conditioned media were collected and analyzed for PGE, by ELISA. Microtubules were fluorescently labeled and analyzed by confocal microscopy to determine microtubule network morphology and height. Centrifugation at 10-g reduced microtubule network height by 15% on d4 and 10% on d6, with variable changes in more mature cultures. No major changes in microtubule morphology were observed. PGE(sub 2) release by d4 cultures increased in a dose-dependent fashion (3-fold at 10-g and 6-fold at 50-g relative to controls). D6 cultures produced a 5-fold increase for both 10-g and 50-g. PGE(sub 2) increased only 1.5-fold by d9, and by d19, PGE(sub 2) was not delectable in either the control or hypergravity-stimulated cells. Thus, as osteoblasts differentiate in culture, responsiveness of the microtubule cytoskeleton and the PGE(sub 2) pathway to hypergravity declines.

Global exploration and production capacity for platinum-group metals from 1995 through 2015

Science.gov (United States)

Wilburn, David R.

2012-01-01

Platinum-group metals (PGMs) are required in a variety of commercial, industrial, and military applications for many existing and emerging technologies, yet the United States is highly dependent on foreign sources of PGMs. Information on global exploration for PGMs since 1995 has been used in this study as a basis for identifying locations where the industry has determined that exploration has provided data sufficient to warrant development of a new mine or expansion of an existing operation or where a significant increase in capacity for PGMs is anticipated by 2015. Discussions include an overview of the industry and the selected sites, factors affecting mineral supply, and circumstances leading to the development of mineral properties with the potential to affect mineral supply. Of the 52 sites or regional operations that were considered in this analysis, 16 sites were producing before 1995, 28 sites commenced production from 1995 through 2010, and 8 sites were expected to begin production from 2011 through 2015 if development plans came to fruition. The United States imports PGMs primarily from Canada, Russia, South Africa, and Zimbabwe to meet increasing demand for these materials in a variety of specialized and high-tech applications. Feed sources of PGMs are changing in South Africa and Russia, which together accounted for about 89 percent of platinum production and 82 percent of palladium production in 2009. A greater amount of South African PGM capacity is likely to come from deeper, higher cost Upper Group Reef seam 2 deposits and deposits in the Eastern Bushveld area. Future Russian PGM capacity is likely to come from ore zones with generally lower PGM content and different platinum-to-palladium ratios than the nickel-rich ore that dominated PGM supply in the 1990s. Because PGM supply from Canada and Russia is derived as a byproduct of copper and nickel mining, the PGM supply from these countries is influenced by economic, environmental, political, and

GIS-based identification of areas that have resource potential for critical minerals in six selected groups of deposit types in Alaska

Science.gov (United States)

Karl, Susan M.; Jones, James V.; Hayes, Timothy S.

2016-11-16

Alaska has considerable potential for undiscovered mineral resources. This report evaluates potential for undiscovered critical minerals in Alaska. Critical minerals are those for which the United States imports more than half of its total supply and which are largely derived from nations that cannot be considered reliable trading partners. In this report, estimated resource potential and certainty for the state of Alaska are analyzed and mapped for the following six selected mineral deposit groups that may contain one or more critical minerals: (1) rare earth elements-thorium-yttrium-niobium(-uranium-zirconium) [REE-Th-Y-Nb(-U-Zr)] deposits associated with peralkaline to carbonatitic igneous intrusive rocks; (2) placer and paleoplacer gold (Au) deposits that in some places might also produce platinum group elements (PGE), chromium (Cr), tin (Sn), tungsten (W), silver (Ag), or titanium (Ti); (3) platinum group elements(-cobalt-chromium-nickel-titanium-vanadium) [PGE(-Co-Cr-Ni-Ti-V)] deposits associated with mafic to ultramafic intrusive rocks; (4) carbonate-hosted copper(-cobalt-silver-germanium-gallium) [Cu(-Co-Ag-Ge-Ga)] deposits; (5) sandstone-hosted uranium(-vanadium-copper) [U(-V-Cu)] deposits; and (6) tin-tungsten-molybdenum(-tantalum-indium-fluorspar) [Sn-W-Mo(-Ta-In-fluorspar)] deposits associated with specialized granites.This study used a data-driven, geographic information system (GIS)-implemented method to identify areas that have mineral resource potential in Alaska. This method systematically and simultaneously analyzes geoscience data from multiple geospatially referenced datasets and uses individual subwatersheds (12-digit hydrologic units) as the spatial unit of classification. The final map output uses a red, yellow, green, and gray color scheme to portray estimated relative potential (High, Medium, Low, Unknown) for each of the six groups of mineral deposit types, and it indicates the relative certainty (High, Medium, Low) of that estimate for

Efeitos da prostaglandina E1 (PGE1 na gênese de capilares sanguíneos em músculo esquelético isquêmico de ratos: estudo histológico Effects of prostaglandin E1 (PGE1 in the genesis of blood capillaries in rat ischemic skeletal muscle: histological study

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Dorival Moreschi Jr.

2007-12-01

purpose. OBJECTIVE: To study morphologic aspects in the genesis of blood capillaries in the lower limb skeletal muscle of rats submitted to ischemia under the action of intramuscular (IM or endovenous (EV PGE1. METHODS: Forty-eight Wistar-UEM rats were randomly distributed into three groups of 16, equally redistributed into two subgroups, observed at the 7th and 14th days as follows: one control group, which had only limb ischemia; one group with ischemia and IM injection of PGE1; and one group with ischemia and EV injection of PGE1. To analyze the results, hematoxylin-eosin (HE and immunohistochemical staining were used. RESULTS: There was a statistically significant increase in the number of capillaries in the subgroups using IM or EV PGE1, through counting in the samples containing HE staining. Immunostaining was not efficient for the quantification of capillaries. CONCLUSIONS: IM or EV PGE1 resulted in an increase in number of capillaries in the skeletal muscle of rats submitted to ischemia after 14 days of observation, which was histologically identifiable through HE staining. Immunostaining was not successful in establishing a correlation with the increase in vessels found in HE staining.

Outstanding low temperature HC-SCR of NOx over platinum-group catalysts supported on mesoporous materials expecting diesel-auto emission regulation

International Nuclear Information System (INIS)

Komatsu, Tamikuni; Tomokuni, Keizou; Yamada, Issaku

2006-01-01

Outstanding low temperature HC-SCR of NOx over platinum-group catalysts supported on mesoporous materials, which does not rely on the conventional NOx-absorption-reduction-catalysts, is presented for the purpose of de-NOx of diesel-auto emissions. The established catalysts basically consist of mesoporous silica or metal-substituted mesoporous silicates for supports and platinum for active species, which is operated under lean- and rich-conditions. The new catalysts are very active at 150-200 o C and free from difficult problems of SOx-deactivation and hydrothermal ageing of the NOx-absorption-reduction catalyst. (author)

THE INVESTIGATION OF EFFECT OF FLURBIPROFEN AXETIL ON THE TISSUE GROWTH AND THE CONTENT OF PGE2 IN CERVICAL CANCER.

Science.gov (United States)

Lu, Jing; Wang, Shenggang; Chen, Guiying; Sun, Xiaofeng; Li, Kezhong

2016-11-01

The aim of this study was to investigate whether flurbiprofen axetil can inhibit the tissue growth and the content of PGE2 in cervical cancer or not. Fifty female BALB/c nude mice were randomly divided into control group (C), tumor + saline group (T), tumor + flurbiprofen axetil 10 mg/kg (Cfl0) group, tumor + flurbiprofen axetil 25 mg/kg (Cf25) group, tumor + flurbiprofen axetil tumor 50 mg/kg (Cf50), so that each group had 10 animals. Then, the animal model of human cervical carcinoma was established, and the relative tumor volume (RTV), relative tumor proliferation rate (T/C) and tumor inhibition rate were measured. The content of PGE2 in tumor tissue was determined by using enzyme-linked immunosorbent assay. There was no tumor formation in group C, and the time of tumor growth in other groups was non-statistically different. The RVT in Cf50 group was lower than in other groups. It was evident from the curve of tumor growth that the tumor weight in T group was evidently higher than that of administration groups (p Flurbiprofen axetil can inhibit the growth of cervical cancer transplanted tumor in nude mice and this inhibitory effect was maximal in Cf50 group. Flurbiprofen axetil can inhibit the production of PGE2 in tumor tissue of cervical carcinoma in nude mice.

First determination of the levels of platinum group metals in Manta birostris (manta ray) caught along the Ghanaian coastline.

Science.gov (United States)

Essumang, D K

2010-06-01

Tissues from Manta birostris caught by fishermen from Dixcove in the western part of Ghana were analyzed for their Platinum, palladium and rhodium concentrations (PGM). The use of chondrichthyan fish has permitted the study of trace levels of Platinum group metals (PGMs) which have travelled very far into the sea. The analysis showed that Ghana's coastline is fairly polluted with these platinum group metals (PGMs). PGM concentration in manta ray recorded a range of (0.15-0.85) microg/g for Pt, (0.033-0.67) microg/g for Pd and (0.007-0.145) microg/g for Rh. Comparing these values to the UK dietary intake of 0.2 microg/day for Pt and Rh and 1.0 microg/day for Pd, its indicates that the values obtained from the analysis for Pt was above the required level. This is the first study to show the accumulation of PGM in chondrichthyan fish, although the sources of this pollution are not clear as manta birostris is migratory and therefore need to be investigated further. The presence of the PGM is very significant, since manta ray meat is consumed in Ghana. This may presents a health risk, due to a possible accumulation of PGMs in humans.

Catalytic polarographic currents of platinum metal complexes and their application to determination of trace concentrations of the elements

International Nuclear Information System (INIS)

Ezerskaya, N.A.; Kiseleva, I.N.

1984-01-01

Several types of catalytic electrode processes with the participation of platinum metal complexes and used for the determination of the element microconcentrations have been considered in the review. It is pointed out that to measure catalytic currents of hydrogen solutions nitroso compounds, which are prepared by heating chloride complexes of Ru(3) and (4) with NaNO 2 are used. The method is applicable for ruthenium determination in commercial nitric acid solutions. Ru determination in solution of ruthenium (4) dimeric chloride complex on graphite electrode, using catalytic currents of hydrogen, surpasses in sensitivity the determination of the element, using the method of inversion voltammetry. Certain other complexes of Ru and determination methods of ruthenium in them are considered. Hydrogen catalytic currents in the complexes solutions with organic ligands are the most perspective for analysis

Induction of labour by balloon catheter with extra-amniotic saline infusion (BCEAS): a randomised comparison with PGE2 vaginal pessaries

DEFF Research Database (Denmark)

Lyndrup, J; Nickelsen, Carsten Nahne Amtof; Weber, Tom

1994-01-01

OBJECTIVE: A new method for induction of labour--balloon catheter with extra-amniotic saline infusion (BCEAS)--is evaluated in randomised comparison with prostaglandin E2 (PGE2) in vaginal pessaries. STUDY GROUP: One-hundred and nine pregnant women with unfavourable cervices. MAJOR OUTCOME MEASURES......: The efficiency of inducing vaginal delivery and the level of 'disadvantages following induction of labour' (DisFIL scorings). RESULTS: Overall, BCEAS was less efficient inducing vaginal delivery than vaginal PGE2 (P women (P ...) primiparous women group, and particularly in the subgroup of these having very low pelvic scores (Lange score,

Lipo-PGE1 suppresses collagen production in human dermal fibroblasts via the ERK/Ets-1 signaling pathway.

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Yoolhee Yang

Full Text Available Dysregulation of collagen production contributes to various pathological processes, including tissue fibrosis as well as impaired wound healing. Lipo-prostaglandin E1 (Lipo-PGE1, a lipid microsphere-incorporated prostaglandin E1, is used as a vasodilator for the treatment of peripheral vascular diseases. Lipo-PGE1 was recently shown to enhance human dermal fibroblast (HDF migration and in vivo wound healing. No published study has characterized the role of Lipo-PGE1 in collagen regulation in HDFs. Here, we investigated the cellular signaling mechanism by which Lipo-PGE1 regulates collagen in HDFs. Collagen production was evaluated by the Sircol collagen assay, Western blot analysis of type I collagen and real time PCR. Unexpectedly, Lipo-PGE1 decreased mRNA expression of collagen 1A1, 1A2, and 3A1. Lipo-PGE1 markedly inhibited type I collagen and total soluble collagen production. In addition, Lipo-PGE1 inhibited transforming growth factor-β-induced collagen expression via Smad2 phosphorylation. To further investigate whether extracellular signal-regulated kinase (ERK/Ets-1 signaling, a crucial pathway in collagen regulation, is involved in Lipo-PGE1-inhibited collagen production, cells were pretreated with an ERK-specific inhibitor, PD98059, prior to the addition of Lipo-PGE1. Lipo-PGE1-inhibited collagen mRNA expression and total soluble collagen production were recovered by pretreatment with PD98059. Moreover, Lipo-PGE1 directly induced the phosphorylation of ERK. Furthermore, silencing of Ets-1 recovered Lipo-PGE1-inhibited collagen production and PD98059 blocked Lipo-PGE1-enhanced Ets-1 expression. The present study reveals an important role for Lipo-PGE1 as a negative regulator of collagen gene expression and production via ERK/Ets-1 signaling. These results suggest that Lipo-PGE1 could potentially be a therapeutic target in diseases with deregulated collagen turnover.

A combined radiation and platinum chemotherapy for esophageal carcinoma

International Nuclear Information System (INIS)

Takamura, Akio; Saito, Hiroya; Sakurai, Yasuo; Horio, Keiji; Mizoe, Junetsu.

1993-01-01

The prognosis of the patients with advanced esophageal carcinoma treated by definitive radiotherapy is still dismal with a reported 5-year survival rate of 5-10% in most series. Since 1986, combined radiotherapy with chemotherapy using platinum analogue was initiated at Asahikawa and Obihiro Kosei Hospitals in order to improve local-regional control and the survival of the patients. From 1980 to 1992, 81 patients with unresectable esophageal carcinoma were treated with radiotherapy. Since April 1986, 37 out of the 81 patients received both radiotherapy and chemotherapy with platinum. Platinum was used during the course of radiotherapy. The method of administration of platinum was as follows; Cisplatin intravenously (50 mg, weekly, total 200 mg) in 9 patients, Carboplatin intravenously (100-150 mg, weekly, total 400-900 mg) in 11 patients and Cisplatin intraarterially (100 mg, at a 3-4 week interval, total 100-300 mg) in 17 patients. These 37 patients (Group A) were compared to 44 patients treated by radiotherapy alone (Group B) with respect to initial response and survival rate. Response was defined according to the guidelines recommended by Japanese Society for Esophageal Diseases. Response rates were 59.1% (19 CR and 7 PR) in Group B and 70.3% (7 CR and 19 PR) in Group A. Primary relapse-free rates were 36.4% in Group B and 37.8% in Group A. The cumulative survival at 3 years were 11.7% in Group B and 10.6% in Group A. Enhancement of side effects by chemotherapy was minimal and acceptable. Improvement of local-regional control and survival was not obvious by adding a concomitant platinum-chemotherapy. A definite conclusion, however, could not be drawn because of the retrospective, non-controlled nature of this study. Introduction of more intensive, multiple agents chemotherapy seems necessary if one aims at improving the results. (author)

Induction of labour by balloon catheter with extra-amniotic saline infusion (BCEAS): a randomised comparison with PGE2 vaginal pessaries

DEFF Research Database (Denmark)

Lyndrup, J; Nickelsen, Carsten Nahne Amtoft; Weber, Tom

1994-01-01

section followed BCEAS than PGE2 (29% and 10%, respectively; P infectious complications were not recorded following BCEAS. No difference was apparent in the status of the neonates (judging from Apgar scores and umbilical artery pH and SBE). The women, delivering vaginally, commented......OBJECTIVE: A new method for induction of labour--balloon catheter with extra-amniotic saline infusion (BCEAS)--is evaluated in randomised comparison with prostaglandin E2 (PGE2) in vaginal pessaries. STUDY GROUP: One-hundred and nine pregnant women with unfavourable cervices. MAJOR OUTCOME MEASURES......: The efficiency of inducing vaginal delivery and the level of 'disadvantages following induction of labour' (DisFIL scorings). RESULTS: Overall, BCEAS was less efficient inducing vaginal delivery than vaginal PGE2 (P

Action of iloprost and PGE1 on global ischemic and reperfused myocardium: a 31P-NMR-study.

Science.gov (United States)

Pissarek, M; Gründer, W; Keller, T; Goos, H; Mest, H J; Krause, E G

1988-01-01

The influence of iloprost, PGE1 and of the combined application of iloprost and PGE1 on high energy phosphate contents was investigated in isolated rat hearts perfused aerob at 37 degrees C in Langendorff mode. Changes in creatine phosphate, ATP and inorganic phosphate were registered during 20 minutes of global ischemia and 56 minutes of reperfusion with 31P-NMR-spectroscopic methods starting drug application prior to ischemia simultaneously with onset of heart perfusion. Most effective in preservation of high energy phosphates was the combined application of PGE1 and iloprost resulting in a creatine phosphate/inorganic phosphate ratio of 103.2 +/- 30.9% of pre-ischemia values compared to 52.5 +/- 6.1% in control group without drug application 0-5 minutes after onset of reperfusion, 148.8 +/- 24.8% vs 78.8 +/- 15.2% at 6-11 minutes of reperfusion and 116.6 +/- 16% vs 68.9 +/- 12.7% at 12-17 minutes of reperfusion. The same trend was observed employing ATP/inorganic phosphate ratio. The improved energy state in reperfused hearts following application of PGE1 and iloprost in combination is presumed to be supported by a reduction of the loss of high energy phosphates (HEP) during global ischemia and by a cytoprotective effect of iloprost immediately after starting reperfusion.

Compositional and isotopic heterogeneities in the Neo-Tethyan upper mantle recorded by coexisting Al-rich and Cr-rich chromitites in the Purang peridotite massif, SW Tibet (China)

Science.gov (United States)

Xiong, Fahui; Yang, Jingsui; Xu, Xiangzhen; Kapsiotis, Argyrios; Hao, Xiaolin; Liu, Zhao

2018-06-01

The Purang harzburgite massif in SW Tibet (China) hosts abundant chrome ore deposits. Ores consist of 20 to >95% modal chromian spinel (Cr-spinel) with mylonitic fabric in imbricate shaped pods. The composition of Cr-spinel in these ores ranges from Al-rich [Cr#Sp or Cr/(Cr + Al) × 100 = 47.60-57.56] to Cr-rich (Cr#Sp: 62.55-79.57). Bulk platinum-group element (PGE) contents of chromitites are also highly variable ranging from 17.5 ppb to ∼2.5 ppm. Both metallurgical and refractory chromitites show a general enrichment in the IPGE (Os, Ir and Ru) with respect to the PPGE (Rh, Pt and Pd), resulting mostly in right-sloping primitive mantle (PM)-normalized PGE profiles. The platinum-group mineral (PGM) assemblages of both chromitite types are dominated by heterogeneously distributed, euhedral Os-bearing laurite inclusions in Cr-spinel. The Purang chromitites have quite inhomogeneous 187Os/188Os ratios (0.12289-0.13194) that are within the range of those reported for mantle-hosted chromitites from other peridotite massifs. Geochemical calculations demonstrate that the parental melts of high-Cr chromitites were boninitic, whereas those of high-Al chromitites had an arc-type tholeiitic affinity. Chromite crystallization was most likely stimulated by changes in magma compositions due to melt-peridotite interaction, leading to the establishment of a heterogeneous physicochemical environment during the early crystallization of the PGM. The highly variable PGE contents, inhomogeneous Os-isotopic compositions and varying Cr#Sp ratios of these chromitites imply a polygenetic origin for them from spatially distinct melt inputs. The generally low γOs values (different sections of a heterogeneously depleted mantle source region. These melts were most likely produced in the mantle wedge above a downgoing lithospheric slab.

DMPD: Cytokines, PGE2 and endotoxic fever: a re-assessment. [Dynamic Macrophage Pathway CSML Database

Lifescience Database Archive (English)

Full Text Available 15967158 Cytokines, PGE2 and endotoxic fever: a re-assessment. Blatteis CM, Li S, L... (.svg) (.html) (.csml) Show Cytokines, PGE2 and endotoxic fever: a re-assessment. PubmedID 15967158 Title C...ytokines, PGE2 and endotoxic fever: a re-assessment. Authors Blatteis CM, Li S, L

On the nature of oxygen-containing surface groups on carbon nanofibers and their role for platinum deposition—an xps and titration study

NARCIS (Netherlands)

Plomp, A.J.; Su, D.S.; de Jong, K.P.; Bitter, J.H.

2009-01-01

XPS and acid−base titrations were used to investigate the nature and stability of oxygen-containing surface groups on carbon nanofibers (CNF) and platinum-containing CNF. During heat treatments in inert atmosphere at 973 K all acidic (carboxylic) oxygen surface groups were removed for CNF.

A comparative study of the elemental composition of the exhaust emissions of cars powered by liquefied petroleum gas and unleaded petrol

Science.gov (United States)

Lim, McKenzie C. H.; Ayoko, Godwin A.; Morawska, Lidia; Ristovski, Zoran D.; Jayaratne, E. Rohan; Kokot, Serge

Elements emitted from the exhausts of new Ford Falcon Forte cars powered by unleaded petrol (ULP) and liquefied petroleum gas (LPG) were measured on a chassis dynamometer. The measurements were carried out in February, June and August 2001, and at two steady state driving conditions (60 and 80 km h -1). Thirty seven elements were quantified in the exhaust samples by inductively coupled plasma mass spectrometry (ICPMS). The total emission factors of the elements from the exhausts of ULP cars were higher than those of LPG cars at both engine speeds even though high variability in the exhaust emissions from different cars was noted. The effect of the operating conditions such as mileage of the cars, engine speed, fuel and lubricating oil compositions on the emissions was studied. To investigate the effects of these conditions, multivariate data analysis methods were employed including exploratory principal component analysis (PCA), and the multi-criteria decision making methods (MCDM), preference ranking organization method for enrichment evaluation (PROMETHEE) and geometrical analysis for interactive aid (GAIA), for ranking the cars on the basis of the emission factors of the elements. PCA biplot of the complete data matrix showed a clear discrimination of the February, June and August emission test results. In addition, (i) platinum group elements (PGE) emissions were separated from each other in the three different clusters viz. Pt with February, Pd with June and Rh with August; (ii) the motor oil related elements, Zn and P, were particularly associated with the June and August tests (these vectors were also grouped with V, Al and Cu); and (iii) highest emissions of most major elements were associated with the August test after the cars have recorded their highest mileage. Extensive analysis with the aid of the MCDM ranking methods demonstrated clearly that cars powered by LPG outperform those powered by ULP. In general, cars tested in June perform better than

Platinum-Group Minerals and Other Accessory Phases in Chromite Deposits of the Alapaevsk Ophiolite, Central Urals, Russia

Directory of Open Access Journals (Sweden)

Federica Zaccarini

2016-10-01

Full Text Available An electron microprobe study has been carried out on platinum-group minerals, accessory phases, and chromite in several chromite deposits of the Alapaevsk ophiolite (Central Urals, Russia namely the Bakanov Kluch, Kurmanovskoe, Lesnoe, 3-d Podyony Rudnik, Bol’shaya Kruglyshka, and Krest deposits. These deposits occur in partially to totally serpentinized peridotites. The microprobe data shows that the chromite composition varies from Cr-rich to Al-rich. Tiny platinum-group minerals (PGM, 1–10 µm in size, have been found in the chromitites. The most abundant PGM is laurite, accompanied by minor cuproiridsite and alloys in the system Os–Ir–Ru. A small grain (about 20 μm was found in the interstitial serpentine of the Bakanov Kluch chromitite, and its calculated stoichiometry corresponds to (Ni,Fe5P. Olivine, occurring in the silicate matrix or included in fresh chromite, has a mantle-compatible composition in terms of major and minor elements. Several inclusions of amphibole, Na-rich phlogopite, and clinopyroxene have been identified. The bimodal Cr–Al composition of chromite probably corresponds to a vertical distribution in the ophiolite sequence, implying formation of Cr-rich chromitites in the deep mantle, and Al-rich chromitites close to the Moho-transition zone, in a supra-subduction setting. The presence of abundant hydrous silicate inclusions, such as amphibole and phlogopite, suggests that the Alapaevsk chromitites crystallized as a result of the interaction between a melt enriched in fluids and peridotites. Laurite and cuproiridsite are considered to be magmatic in origin, i.e., entrapped as solid phases during the crystallization of chromite at high temperatures. The sulfur fugacity was relatively high to allow the precipitation of Ir-bearing sulfides, but below the Os–OsS2 buffer. The alloys in the system Os–Ir–Ru are classified as secondary PGM, i.e., formed at low temperature during the serpentinization process. The

Solvent extraction of platinum with thiobenzanilide. Separation of platinum from copper

International Nuclear Information System (INIS)

Shkil', A.N.; Zolotov, Yu.A.

1989-01-01

The solvent extraction of micro concentrations of platinum has been investigated from hydrochloric acid media using thiobenzanilide in the presence of SnCl 2 and KI. In the presence of SnCl 2 platinum is extracted rapidly and to significant completion. Conditions have been developed for the quantitative extraction of platinum. The authors have also examined the solvent extraction of copper(II) using thiobenzanilide, interference due to copper(II) and iron(III) on solvent extraction of platinum, and methods to suppress this interference. A procedure has also been developed for the separation of platinum from copper. Solvent extraction of metals was studied using radioactive isotopes: 197 Pt, 64 Cu, 59 Fe, 198 Au, 109 Pd, 110m Ag

Gram-negative, but not Gram-positive, bacteria elicit strong PGE2 production in human monocytes.

Science.gov (United States)

Hessle, Christina C; Andersson, Bengt; Wold, Agnes E

2003-12-01

Gram-positive and Gram-negative bacteria induce different cytokine patterns in human mononuclear cells. We have seen that Gram-positives preferentially induce IL-12 and TNF-alpha, whereas Gram-negatives induce more IL-10, IL-6, and IL-8. In this study, we compared the capacity of these two groups of bacteria to induce PGE2. Monocytes stimulated with Gram-negative bacterial species induced much more PGE2 than did Gram-positive bacteria (5600 +/- 330 vs. 1700 +/- 670 pg/mL, p Gram-positive and Gram-negative bacteria. We suggest that Gram-positive and Gram-negative bacteria may stimulate different innate effector functions; Gram-positive bacteria promoting cell-mediated effector functions whereas Gram-negative bacteria inducing mediators inhibiting the same.

MYEOV (myeloma overexpressed gene) drives colon cancer cell migration and is regulated by PGE2.

LENUS (Irish Health Repository)

Lawlor, Garrett

2010-01-01

INTRODUCTION: We have previously reported that Myeov (MYEloma OVerexpressed gene) expression is enhanced in colorectal cancer (CRC) and that it promotes CRC cell proliferation and invasion. The role of Myeov in CRC migration is unclear. ProstaglandinE2 (PGE 2) is a known factor in promoting CRC carcinogenesis. The role of PGE 2 in modulating Myeov expression has also not been defined. AIM: To assess the role of Myeov expression in CRC cell migration and to evaluate the role of PGE 2 in Myeov bioactivity. METHODS: siRNA mediated Myeov knockdown was achieved in T84 CRC cells. Knockdown was assessed using quantitative real time PCR. The effect of knockdown on CRC cell migration was assessed using a scratch wound healing assay. Separately, T84 cells were treated with PGE 2 (0.00025 micro M, 0.1 micro M and 1 micro M) from 30 min to 3 hours and the effect on Myeov gene expression was assessed using real time PCR. RESULTS: Myeov knockdown resulted in a significant reduction in CRC cell migration, observable as early as 12 hours (P < 0.05) with a 39% reduction compared to control at 36 hours (p < 0.01). Myeov expression was enhanced after treatment with PGE 2, with the greatest effect seen at 60 mins for all 3 PGE 2 doses. This response was dose dependent with a 290%, 550% & 1,000% increase in Myeov expression for 0.00025 micro M, 0.1 micro M and 1 micro M PGE 2 respectively. CONCLUSION: In addition to promoting CRC proliferation and invasion, our findings indicate that Myeov stimulates CRC cell migration, and its expression may be PGE 2 dependant.

Myeov (myeloma overexpressed gene) drives colon cancer cell migration and is regulated by PGE2

LENUS (Irish Health Repository)

Lawlor, Garrett

2010-06-22

Abstract Introduction We have previously reported that Myeov (MYEloma OVerexpressed gene) expression is enhanced in colorectal cancer (CRC) and that it promotes CRC cell proliferation and invasion. The role of Myeov in CRC migration is unclear. ProstaglandinE2 (PGE 2) is a known factor in promoting CRC carcinogenesis. The role of PGE 2 in modulating Myeov expression has also not been defined. Aim To assess the role of Myeov expression in CRC cell migration and to evaluate the role of PGE 2 in Myeov bioactivity. Methods siRNA mediated Myeov knockdown was achieved in T84 CRC cells. Knockdown was assessed using quantitative real time PCR. The effect of knockdown on CRC cell migration was assessed using a scratch wound healing assay. Separately, T84 cells were treated with PGE 2 (0.00025 μ M, 0.1 μ M and 1 μ M) from 30 min to 3 hours and the effect on Myeov gene expression was assessed using real time PCR. Results Myeov knockdown resulted in a significant reduction in CRC cell migration, observable as early as 12 hours (P < 0.05) with a 39% reduction compared to control at 36 hours (p < 0.01). Myeov expression was enhanced after treatment with PGE 2, with the greatest effect seen at 60 mins for all 3 PGE 2 doses. This response was dose dependent with a 290%, 550% & 1,000% increase in Myeov expression for 0.00025 μ M, 0.1 μ M and 1 μ M PGE 2 respectively. Conclusion In addition to promoting CRC proliferation and invasion, our findings indicate that Myeov stimulates CRC cell migration, and its expression may be PGE 2 dependant.

Group theoretical classification of chemical elements

International Nuclear Information System (INIS)

Byakov, V.M.; Kulakov, V.I.; Rumer, Y.B.; Fet, A.L.

1977-01-01

The method of classification of chemical elements, based on group symmetry principles, is compared with element properties. Elements are considered to be states of a single quantum system, the atomic structure being ignored. Elements treated as states of the system, break down into successively diminishing subsystems, big and small multiplets. The theory, being a group classification, does not describe in detail any of element properties, but leads to a unified qualitative description of all of them simultaneously

Factors Governing concentration of platinum group elements in layered complexes

DEFF Research Database (Denmark)

Makovicky, E.; Rose-Hansen, J.; Karup-Møller, Sven

1996-01-01

This report covers the synthetic research results obtained by the Danish group on: (1) The phase system Fe-Ir-S at 1100o, 1000o and 800oC, (2) Metal-rich portions of the phase system Pt-Ir-Fe-S: Pt-Fe-Ir alloys and associated sulfides at 1000oC and 1100oC, (3) The Fe (Cu)-Pt-Rh-S system: alloys...

mPGES-1-derived PGE2 mediates dehydration natriuresis

Science.gov (United States)

Jia, Zhanjun; Liu, Gang; Sun, Ying; Kakizoe, Yutaka; Guan, Guangju; Zhang, Aihua; Zhou, Shu-Feng

2013-01-01

PGE2 is a natriuretic factor whose production is elevated after water deprivation (WD) but its role in dehydration natriuresis is not well-defined. The goal of the present study was to investigate the role of microsomal prostaglandin E synthase-1 (mPGES-1) in dehydration natriuresis. After 24-h WD, wild-type (WT) mice exhibited a significant increase in 24-h urinary Na+ excretion accompanied with normal plasma Na+ concentration and osmolality. In contrast, WD-induced elevation of urinary Na+ excretion was completely abolished in mPGES-1 knockout (KO) mice in parallel with increased plasma Na+ concentration and a trend increase in plasma osmolality. WD induced a 1.8-fold increase in urinary PGE2 output and a 1.6-fold increase in PGE2 content in the renal medulla of WT mice, both of which were completely abolished by mPGES-1 deletion. Similar patterns of changes were observed for urinary nitrate/nitrite and cGMP. The natriuresis in dehydrated WT mice was associated with a significant downregulation of renal medullary epithelial Na channel-α mRNA and protein, contrasting to unaltered expressions in dehydrated KO mice. By quantitative RT-PCR, WD increased the endothelial nitric oxide synthase (eNOS), inducible NOS, and neuronal NOS expressions in the renal medulla of WT mice by 3.9-, 1.48-, and 2.6-fold, respectively, all of which were significantly blocked in mPGES-1 KO mice. The regulation of eNOS expression was further confirmed by immunoblotting. Taken together, our results suggest that mPGES-1-derived PGE2 contributes to dehydration natriuresis likely via NO/cGMP. PMID:23171554

PGE decides to close plant now, not in 1996

International Nuclear Information System (INIS)

Anon.

1993-01-01

On January 4, two months and a day after the Trojan nuclear power reactor survived two ballot initiatives that sought to have the 1095-MWe pressurized water reactor closed immediately, the board of directors of Portland General Electric Company voted to do what those initiatives had wanted done. Trojan went off line on November 9 because of a leak in a steam generator tube. It will not return to service ever again, even though PGE had originally planned to keep running the plant until 1996. The utility announced that immediate closure was now the least-cost choice for ratepayers, mainly because of uncertainty over what would have to be done at the plant to satisfy the Nuclear Regulatory Commission - within which, according to PGE, there was a scientific disagreement over the adequacy of the plant's steam generators to support operation until 1996. PGE has not yet firmed up its decommissioning plan for Trojan. Also, at this writing, there had been no indication whether the absence of Trojan might improve the chances for completion of the region's two mothballed nuclear projects, Washington Public Power Supply System's WNP-1 and -3

The effect of PGE2, gastrin and CCK-8 on postirradiation recovery of small intestine epithelium

International Nuclear Information System (INIS)

Dziekiewicz, M.; Chomiczewski, K.; Jablonska, H.

1997-01-01

The role of some natural factors in the postirradiation recovery of intestinal epithelium is a very interesting and inscrutable problem. In our experiment the comparative effect of PGE 2 , Gastrin and CCK-8 fragment of Cholecystokinin on this problem has been investigated. Male Swiss PZH mice 8 weeks old were irradiated to the whole body with a dose of 5.5 Gy and to abdomen with a dose of 12 Gy of gamma rays. The first experimental group received PGE 2 before 30 min. irradiation, the second received Gastrin after irradiation during 5 days, the third was injected with CCK-8 after irradiation during 5 days too. Unirradiated and only irradiated animals served as control groups. Survival of 30 mice in every group was registered during 30 days after irradiation. The another part of animals in every group were killed between 1 and 12 days after irradiation. Changes in the body weight were registered. Using computer image analysis system , some histological slides were examined, adding the statistical analysis of results. The preliminary results suggest that all those factors are able to stimulate the postirradiation regeneration of small intestinal epithelium (author)

DMPD: Mechanism of age-associated up-regulation in macrophage PGE2 synthesis. [Dynamic Macrophage Pathway CSML Database

Lifescience Database Archive (English)

Full Text Available 15331118 Mechanism of age-associated up-regulation in macrophage PGE2 synthesis. Wu...e-associated up-regulation in macrophage PGE2 synthesis. PubmedID 15331118 Title Mechanism of age-associated... up-regulation in macrophage PGE2 synthesis. Authors Wu D, Meydani SN. Publicatio

Ni MINERALIZATION AND PGE CHARACTERIZATION IN THE ...

African Journals Online (AJOL)

Mgina

fractionation, (2) the IPGEs are often associated with chromites as alloys or sulfides in ... Key words: Tanzania, Kabanga, Luhuma, PGE, Ni-Cu sulfides .... massive sulfide based on size of ore zone ... to ≤ 0.1 wt% and Fe2O3T = 80- ≈ 87 wt%.

Peruvian perovskite Between Transition-metal to PGM/PlatinumGroupMetal Catalytic Fusion

Science.gov (United States)

Maksoed, Wh-

2016-11-01

Strongly correlated electronic materials made of simple building blocks, such as a transition-metal ion in an octahedral oxygen cage forming a perovskite structure- Dagotto & Tokura for examples are the high-temperature superconductivity & the CMR/Colossal Magnetoresistance . Helium-4 denotes from LC Case,ScD: "Catalytic Fusion of Deuterium into Helium-4"- 1998 dealt with gaseous D2- "contacted with a supported metallic catalyst at superatmospheric pressure". The catalyst is a platinum-group metal, at about 0.5% - 1% by weight, on activated C. Accompanies Stephen J Geier, 2010 quotes "transition metal complexes", the Energy thus produced is enormous, and because the deuterium is very cheap in the form of heavy water (less than US 1/g), the fuel cost is very low (seas &Deuteronomy to be eternally preserves. Heartfelt Gratitudes to HE. Mr. Prof. Ir. HANDOJO.

A new approach to precious metals recovery from brown coals: Correlation of recovery efficacy with the mechanism of metal-humic interactions

Science.gov (United States)

Bratskaya, Svetlana Yu.; Volk, Alexandra S.; Ivanov, Vladimir V.; Ustinov, Alexander Yu.; Barinov, Nikolay N.; Avramenko, Valentin A.

2009-06-01

The presence of gold and platinum group elements (PGE) in low-rank brown coals around the world has promoted interest in the industrial exploitation of this alternative source of precious metals. However, due to low efficacy of the methods traditionally used for the processing of mineral ores, there exists a high demand for new strategies of precious metal recovery from refractory carbonaceous materials that could significantly increase the economic potential of gold- and PGE-bearing organic resources. Here we discuss the possibility of gold and PGE recovery from alkaline extracts of brown coals using the difference in colloidal stability of bulk organic matter and its fractions enriched with precious metals. This approach enables one to avoid complete oxidation or combustion of brown coals prior to gold recovery, to minimize organic content in gold concentrate, and to obtain a valuable by-product - humic extracts. Using gold-bearing brown coals from several deposits located in the South Far East of Russia, we show that up to 95% of gold can be transferred to alkaline extracts of humic acids (HA) and up to 85% of this gold can be recovered by centrifugation at pH 4.0-6.0, when only 5-15% of HA precipitated simultaneously. We have shown that the high efficacy of gold recovery can be attributed to the occurrence of fine-dispersed elemental gold particles stabilized by HA, which differ significantly in colloidal stability from the bulk organic matter and, thus, can be separated by centrifugation.

Low-density geochemical mapping at continental scale reveals background for emerging tech-critical elements

OpenAIRE

Négrel , Philippe; Ladenberger , Anna; Reimann , Clemens; Birke , Manfred; Demetriades , Alecos; Sadeghi , Martiya

2018-01-01

International audience; The demand for a variety of mineral and/or element resources (e.g., rare earth elements, platinum group elements, cobalt, beryllium, lithium.. .) has increased with the continued consumption in developed countries and the emergence of developing economies. These elements are essential for maintaining and improving future quality of life, including many high-technology yet low-carbon industries. Two factors have been used by the NRC (National Research Council) to rank c...

Adsorption and temperature-programmed desorption of hydrogen with dispersed platinum and platinum-gold catalysts

Energy Technology Data Exchange (ETDEWEB)

Anderson, J.R.; Foger, K.; Breakspere, R.J.

1979-05-01

Adsorption and temperature-programmed desorption of hydrogen with dispersed platinum and platinum-gold catalysts was studied with 0.9-3Vertical Bar3< platinum on silica gel, aerosil, sodium and lanthanum Y zeolites, and ..gamma..-alumina, and on aerosil-supported gold-platinum alloys containing 2, 10, 24, 33, and 85Vertical Bar3< gold. Surface enrichment with gold in the alloy systems, as derived from hydrogen adsorption data and predicted from surface enrichment theory and electron microscopic measurements of particle size, were in good agreement, which indicated that equilibrium was achieved by the thermal treatment (oxygen at 573/sup 0/K, hydrogen at 620/sup 0/K, repeated cycles) used. Hydrogen spillover to gold was observed at the higher hydrogen pressures tested on the alloys with high gold content, and to the zeolite supports. The temperature-programed desorption profiles were independent of gold content, which indicated that gold acts only as diluent, and that isolated surface platinum atoms become populated with hydrogen atoms either by hydrogen atom spillover from platinum ensembles to gold and from the gold to the isolated platinum, and/or by adsorption of a molecule directly on the isolated platinum and chemisorption of one H atom at an adjacent gold atom. The distribution of surface platinum ensembles was evaluated by a computer simulation method.

Competitive platinum-group-metal (PGM) supply from the Eastern Limb, Bushveld Complex: Geological, mining and mineral economic aspects

CSIR Research Space (South Africa)

McGill, JE

2011-08-01

Full Text Available -GROUP-METAL (PGM) SUPPLY FROM THE EASTERN LIMB, BUSHVELD COMPLEX: GEOLOGICAL, MINING, AND MINERAL ECONOMIC ASPECTS Dr. Jeannette E. McGill & Prof. Murray W. Hitzman ACKNOWLEDGEMENTS ? COUNCIL FOR SCIENTIFIC AND INDUSTRIAL RESEARCH (CSIR) ? Centre for Mining... Innovation ? Office of Graduate Studies, Fogarty Endowment ? Mr. VISHNU PILLAY (EXECUTIVE HEAD: JV?S ? Anglo Platinum) ? ACADEMIC ADVISORS Prof. Murray Hitzman (Economic Geology); Dr. Hugh Miller (Mining Engineering); Prof. Rodderick Eggert (Mineral...

The PGE(2)-EP4 receptor is necessary for stimulation of the renin-angiotensin-aldosterone system in response to low dietary salt intake in vivo

DEFF Research Database (Denmark)

Pöschke, Antje; Kern, Niklas; Maruyama, Takayuki

2012-01-01

, creatinine clearance, and plasma antidiuretic hormone (ADH) concentration. Following salt restriction, plasma renin and aldosterone concentrations and kidney renin mRNA level rose significantly in EP4(+/+) but not in EP4(-/-) and in wild-type mice treated with EP4 antagonist ONO-AE3-208. In the latter two...... groups, the low-salt diet caused a significantly greater rise in PGE(2) excretion. Furthermore, mRNA expression for COX-2 and PGE(2) synthetic activity was significantly greater in EP4(-/-) than in EP4(+/+) mice. We conclude that low dietary salt intake induces expression of COX-2 followed by enhanced...... renal PGE(2) synthesis, which stimulates the renin-angiotensin-aldosterone system by activation of EP4 receptor. Most likely, defects at the step of EP4 receptor block negative feedback mechanisms on the renal COX system, leading to persistently high PGE(2) levels, diuresis, and K(+) loss....

Determination of phosphorus traces in platinum alloys by two-phase isotope exchange

International Nuclear Information System (INIS)

Vlacil, F.

1980-01-01

The method of ZEMAN and KRATZER for the determination of phosphorus traces by means of two-phase isotope exchange was modified for the determination of phosphorus in pure platinum or pure platinum alloys. It was found that Pt, Rh, Ag and As do not interfere with the determination. Among the elements usually present in platinum metal or platinum alloys, only gold interferes. It was removed by extraction from 7M HCl by MIBK and AmOAc. Hydrochloric acid also interferes but it can be removed by evaporation. The analytical procedure is given for the solution obtained by pressure decomposition of the sample (0.5 g) in a steel bomb with PTFE inlay. It is possible to determine > 2 ppm P (approximate error -10%). If using calibration dependence instead of the well known equation for isotope exchange it is not necessary to know the content of P in the standard solution labelled with 32 P. (author)

Preparation and Analysis of Platinum Thin Films for High Temperature Sensor Applications

Science.gov (United States)

Wrbanek, John D.; Laster, Kimala L. H.

2005-01-01

A study has been made of platinum thin films for application as high temperature resistive sensors. To support NASA Glenn Research Center s high temperature thin film sensor effort, a magnetron sputtering system was installed recently in the GRC Microsystems Fabrication Clean Room Facility. Several samples of platinum films were prepared using various system parameters to establish run conditions. These films were characterized with the intended application of being used as resistive sensing elements, either for temperature or strain measurement. The resistances of several patterned sensors were monitored to document the effect of changes in parameters of deposition and annealing. The parameters were optimized for uniformity and intrinsic strain. The evaporation of platinum via oxidation during annealing over 900 C was documented, and a model for the process developed. The film adhesion was explored on films annealed to 1000 C with various bondcoats on fused quartz and alumina. From this compiled data, a list of optimal parameters and characteristics determined for patterned platinum thin films is given.

Elevated COX2 expression and PGE2 production by downregulation of RXRα in senescent macrophages

International Nuclear Information System (INIS)

Chen, Huimin; Ma, Feng; Hu, Xiaona; Jin, Ting; Xiong, Chuhui; Teng, Xiaochun

2013-01-01

Highlights: •Downregulation of RXRα in senescent macrophage. •RXRα suppresses NF-κB activity and COX2 expression. •Increased PGE2 production due to downregulation of RXRα. -- Abstract: Increased systemic level of inflammatory cytokines leads to numerous age-related diseases. In senescent macrophages, elevated prostaglandin E2 (PGE2) production contributes to the suppression of T cell function with aging, which increases the susceptibility to infections. However, the regulation of these inflammatory cytokines and PGE2 with aging still remains unclear. We have verified that cyclooxygenase (COX)-2 expression and PGE2 production are higher in LPS-stimulated macrophages from old mice than that from young mice. Downregulation of RXRα, a nuclear receptor that can suppress NF-κB activity, mediates the elevation of COX2 expression and PGE2 production in senescent macrophages. We also have found less induction of ABCA1 and ABCG1 by RXRα agonist in senescent macrophages, which partially accounts for high risk of atherosclerosis in aged population. Systemic treatment with RXRα antagonist HX531 in young mice increases COX2, TNF-α, and IL-6 expression in splenocytes. Our study not only has outlined a mechanism of elevated NF-κB activity and PGE2 production in senescent macrophages, but also provides RXRα as a potential therapeutic target for treating the age-related diseases

Prostaglandin transporter (OATP2A1/SLCO2A1) contributes to local disposition of eicosapentaenoic acid-derived PGE3.

Science.gov (United States)

Gose, Tomoka; Nakanishi, Takeo; Kamo, Shunsuke; Shimada, Hiroaki; Otake, Katsumasa; Tamai, Ikumi

2016-01-01

Eicosapentaenoic acid (EPA)-derived prostaglandin E3 (PGE3) possesses an anti-inflammatory effect; however, information for transporters that regulate its peri-cellular concentration is limited. The present study, therefore, aimed to clarify transporters involved in local disposition of PGE3. PGE3 uptake was assessed in HEK293 cells transfected with OATP2A1/SLCO2A1, OATP1B1/SLCO1B1, OATP2B1/SLCO2B1, OAT1/SLC22A6, OCT1/SLC22A1 or OCT2/SLC22A2 genes, compared with HEK293 cells transfected with plasmid vector alone (Mock). PGE3 uptake by OATP2A1-expressing HEK293 cells (HEK/2A1) was the highest and followed by HEK/1B1, while no significantly higher uptake of PGE3 than Mock cells was detected by other transporters. Saturation kinetics in PGE3 uptake by HEK/2A1 estimated the Km as 7.202 ± 0.595 μM, which was 22 times higher than that of PGE2 (Km=0.331 ± 0.131 μM). Furthermore, tissue disposition of PGE3 was examined in wild-type (WT) and Slco2a1-deficient (Slco2a1(-/-)) mice after oral administration of EPA ethyl ester (EPA-E) when they underwent intraperitoneal injection of endotoxin (e.g., lipopolysaccharide). PGE3 concentration was significantly higher in the lung, and tended to increase in the colon, stomach, and kidney of Slco2a1(-/-), compared to WT mice. Ratio of PGE2 metabolite 15-keto PGE2 over PGE2 concentration was significantly lower in the lung and colon of Slco2a1(-/-) than that of WT mice, suggesting that PGE3 metabolism is downregulated in Slco2a1(-/-) mice. In conclusion, PGE3 was found to be a substrate of OATP2A1, and local disposition of PGE3 could be regulated by OATP2A1 at least in the lung. Copyright © 2015 Elsevier Inc. All rights reserved.

Graphite-supported platinum catalysts: Effects of gas and aqueous phase treatments

Energy Technology Data Exchange (ETDEWEB)

Vleeming, J.H.; Kuster, B.F.M.; Marin, G.B. [Eindhoven Univ. of Technology (Netherlands)] [and others

1997-03-01

The effects on the platinum particle diameter and the available platinum surface area of a graphite-supported platinum catalyst resulting from pretreatments and from performing a selective oxidation reaction are investigated. In the gas phase considerable catalyst sintering occurs only in the presence of oxygen at 773 K due to extensive carbon burn-off, whereas in an aqueous phase platinum particle growth is limited upon oxidative treatment. A hydrogen treatment in aqueous phase at 363 K causes platinum particle growth, aggregate formation, and covering of metal sites. These phenomena become more important with increasing pH. Platinum particle growth and aggregate formation are attributed to platinum particle rather than platinum adatom mobility and is caused by the destruction of the oxygen-containing surface groups on the graphite support, which serve as anchorage sites for the platinum particles. Site covering is caused by products originating from the graphite support, which are formed as a result of the reductive treatments. When performing the aqueous phase oxidation of methyl {alpha}-D-glucopyranoside at 323 K and a pH of 9, catalyst modifications are small under oxidative conditions. Exposure of the catalyst for several hours to methyl {alpha}-D-glucopyranoside under the same conditions but in the absence of oxygen causes site covering. 50 refs., 9 figs., 1 tab.

Electrochemical DNA biosensors based on platinum nanoparticles combined carbon nanotubes

International Nuclear Information System (INIS)

Zhu Ningning; Chang Zhu; He Pingang; Fang Yuzhi

2005-01-01

Platinum nanoparticles were used in combination with multi-walled carbon nanotubes (MWCNTs) for fabricating sensitivity-enhanced electrochemical DNA biosensor. Multi-walled carbon nanotubes and platinum nanoparticles were dispersed in Nafion, which were used to fabricate the modification of the glassy carbon electrode (GCE) surface. Oligonucleotides with amino groups at the 5' end were covalently linked onto carboxylic groups of MWCNTs on the electrode. The hybridization events were monitored by differential pulse voltammetry (DPV) measurement of the intercalated daunomycin. Due to the ability of carbon nanotubes to promote electron-transfer reactions, the high catalytic activities of platinum nanoparticles for chemical reactions, the sensitivity of presented electrochemical DNA biosensors was remarkably improved. The detection limit of the method for target DNA was 1.0 x 10 -11 mol l -1

Platinum-bearing chromite layers are caused by pressure reduction during magma ascent.

Science.gov (United States)

Latypov, Rais; Costin, Gelu; Chistyakova, Sofya; Hunt, Emma J; Mukherjee, Ria; Naldrett, Tony

2018-01-31

Platinum-bearing chromitites in mafic-ultramafic intrusions such as the Bushveld Complex are key repositories of strategically important metals for human society. Basaltic melts saturated in chromite alone are crucial to their generation, but the origin of such melts is controversial. One concept holds that they are produced by processes operating within the magma chamber, whereas another argues that melts entering the chamber were already saturated in chromite. Here we address the problem by examining the pressure-related changes in the topology of a Mg 2 SiO 4 -CaAl 2 Si 2 O 8 -SiO 2 -MgCr 2 O 4 quaternary system and by thermodynamic modelling of crystallisation sequences of basaltic melts at 1-10 kbar pressures. We show that basaltic melts located adjacent to a so-called chromite topological trough in deep-seated reservoirs become saturated in chromite alone upon their ascent towards the Earth's surface and subsequent cooling in shallow-level chambers. Large volumes of these chromite-only-saturated melts replenishing these chambers are responsible for monomineralic layers of massive chromitites with associated platinum-group elements.

Vaginal Lactoferrin Modulates PGE2, MMP-9, MMP-2, and TIMP-1 Amniotic Fluid Concentrations

Directory of Open Access Journals (Sweden)

Alessandro Trentini

2016-01-01

Full Text Available Inflammation plays an important role in pregnancy, and cytokine and matrix metalloproteases (MMPs imbalance has been associated with premature rupture of membranes and increased risk of preterm delivery. Previous studies have demonstrated that lactoferrin (LF, an iron-binding protein with anti-inflammatory properties, is able to decrease amniotic fluid (AF levels of IL-6. Therefore, we aimed to evaluate the effect of vaginal LF administration on amniotic fluid PGE2 level and MMP-TIMP system in women undergoing genetic amniocentesis. One hundred and eleven women were randomly divided into controls (n=57 or treated with LF 4 hours before amniocentesis (n=54. Amniotic fluid PGE2, active MMP-9 and MMP-2, and TIMP-1 and TIMP-2 concentrations were determined by commercially available assays and the values were normalized by AF creatinine concentration. PGE2, active MMP-9, and its inhibitor TIMP-1 were lower in LF-treated group than in controls (p<0.01, p<0.005, and p<0.001, resp.. Conversely, active MMP-2 (p<0.0001 and MMP-2/TIMP-2 molar ratio (p<0.001 were increased, whilst TIMP-2 was unchanged. Our data suggest that LF administration is able to modulate the inflammatory response following amniocentesis, which may counteract cytokine and prostanoid imbalance that leads to abortion. This trial is registered with Clinical Trial number NCT02695563.

Photophysics of organometallic platinum(II) derivatives of the diketopyrrolopyrrole chromophore

KAUST Repository

Goswami, Subhadip; Winkel, Russell W.; Alarousu, Erkki; Ghiviriga, Ion; Mohammed, Omar F.; Schanze, Kirk S.

2014-01-01

A pair of diketopyrrolopyrrole (DPP) chromophores that are end-functionalized with platinum containing "auxochromes" were subjected to electrochemical and photophysical study. The chromophores contain either platinum acetylide or ortho-metalated 2-thienylpyridinyl(platinum) end-groups (DPP-Pt(CC) and DPP-Pt(acac), respectively). The ground state redox potentials of the chromophores were determined by solution electrochemistry, and the HOMO and LUMO levels were estimated. The chromophores' photophysical properties were characterized by absorption, photoluminescence, and time-resolved absorption spectroscopy on time scales from sub-picoseconds to microseconds. Density functional theory (DFT) computations were performed to understand the molecular orbitals involved in both the singlet and triplet excited state photophysics. The results reveal that in both platinum DPP derivatives the organometallic auxochromes have a significant effect on the chromophores' photophysics. The most profound effect is a reduction in the fluorescence yields accompanied by enhanced triplet yields due to spin-orbit coupling induced by the metal centers. The effects are most pronounced in DPP-Pt(acac), indicating that the orthometalated platinum auxochrome is able to induce spin-orbital coupling to a greater extent compared to the platinum acetylide units. (Figure Presented).

In vitro permeation of platinum and rhodium through Caucasian skin.

Science.gov (United States)

Franken, A; Eloff, F C; Du Plessis, J; Badenhorst, C J; Jordaan, A; Du Plessis, J L

2014-12-01

During platinum group metals (PGMs) refining the possibility exists for dermal exposure to PGM salts. The dermal route has been questioned as an alternative route of exposure that could contribute to employee sensitisation, even though literature has been focused on respiratory exposure. This study aimed to investigate the in vitro permeation of platinum and rhodium through intact Caucasian skin. A donor solution of 0.3mg/ml of metal, K2PtCl4 and RhCl3 respectively, was applied to the vertical Franz diffusion cells with full thickness abdominal skin. The receptor solution was removed at various intervals during the 24h experiment, and analysed with high resolution ICP-MS. Skin was digested and analysed by ICP-OES. Results indicated cumulative permeation with prolonged exposure, with a significantly higher mass of platinum permeating after 24h when compared to rhodium. The mass of platinum retained inside the skin and the flux of platinum across the skin was significantly higher than that of rhodium. Permeated and skin retained platinum and rhodium may therefore contribute to sensitisation and indicates a health risk associated with dermal exposure in the workplace. Copyright © 2014 Elsevier Ltd. All rights reserved.

Photophysics of organometallic platinum(II) derivatives of the diketopyrrolopyrrole chromophore

KAUST Repository

Goswami, Subhadip

2014-12-18

A pair of diketopyrrolopyrrole (DPP) chromophores that are end-functionalized with platinum containing "auxochromes" were subjected to electrochemical and photophysical study. The chromophores contain either platinum acetylide or ortho-metalated 2-thienylpyridinyl(platinum) end-groups (DPP-Pt(CC) and DPP-Pt(acac), respectively). The ground state redox potentials of the chromophores were determined by solution electrochemistry, and the HOMO and LUMO levels were estimated. The chromophores\\' photophysical properties were characterized by absorption, photoluminescence, and time-resolved absorption spectroscopy on time scales from sub-picoseconds to microseconds. Density functional theory (DFT) computations were performed to understand the molecular orbitals involved in both the singlet and triplet excited state photophysics. The results reveal that in both platinum DPP derivatives the organometallic auxochromes have a significant effect on the chromophores\\' photophysics. The most profound effect is a reduction in the fluorescence yields accompanied by enhanced triplet yields due to spin-orbit coupling induced by the metal centers. The effects are most pronounced in DPP-Pt(acac), indicating that the orthometalated platinum auxochrome is able to induce spin-orbital coupling to a greater extent compared to the platinum acetylide units. (Figure Presented).

Enhanced Dissolution of Platinum Group Metals Using Electroless Iron Deposition Pretreatment

Science.gov (United States)

Taninouchi, Yu-ki; Okabe, Toru H.

2017-12-01

In order to develop a new method for efficiently recovering platinum group metals (PGMs) from catalyst scraps, the authors investigated an efficient dissolution process where the material was pretreated by electroless Fe deposition. When Rh-loaded alumina powder was kept in aqua regia at 313 K (40 °C) for 30 to 60 minutes, the Rh hardly dissolved. Meanwhile, after electroless Fe plating using a bath containing sodium borohydride and potassium sodium tartrate as the reducing and complexing agents, respectively, approximately 60 pct of Rh was extracted by aqua regia at 313 K (40 °C) after 30 minutes. Furthermore, when heat treatment was performed at 1200 K (927 °C) for 60 minutes in vacuum after electroless plating, the extraction of Rh approached 100 pct for the same leaching conditions. The authors also confirmed that the Fe deposition pretreatment enhanced the dissolution of Pt and Pd. These results indicate that an effective and environmentally friendly process for the separation and extraction of PGMs from catalyst scraps can be developed utilizing this Fe deposition pretreatment.

Neutron activation analysis and the geochemistry of common and trace elements at extinction boundaries in the geological record

International Nuclear Information System (INIS)

Attrep, M. Jr.; Orth, C.J.; Quintana, L.R.

1994-01-01

The discovery of the iridium anomaly at the 65-Ma Cretaceous-Tertiary (K-T) extinction boundary initiated numerous investigations, including the search for the coupling of these extinctions with other astronomical events. One hypothesis is that these periodic extinctions are coupled to terrestrial impacts from cyclic swarms of comets or asteroids. The studies have focused on elucidating the conditions and causes of extinction of life at these geological boundaries using elemental abundance patterns. The authors use instrumental neutron activation methods to determine whole-rock abundances for about 40 trace and common elements in thousands of samples. The platinum group elements (iridium, gold, platinum, and osmium) and nickel are measured by radiochemical activation analysis. The authors can measure iridium at levels down to 1 picogram/gram level

Neutron activation analysis in trace element determinaton in studies of wound healing and in the framework of dose-effect studies on platinum-containing cancer chemotherapeutics

International Nuclear Information System (INIS)

Trebert Haeberlin, S.

1986-01-01

The origin of the iron concentration in wound tissues was studied. To differentiate between blood and tissue iron the erythrocytes of a rabbit were marked with radioactive 55 Fe. Under the assumption that the half-life of rabbit erythrocytes of 34.5 days would not be changed by 55 Fe marking, the 55 Fe activity found in samples taken from the wound area of muscle cut wounds in a healing time of up to 14 days should be a measure for the blood iron share in the wound. The total iron content was determined be measuring 59 Fe with the help of NAA. The portion of iron which was from the tissues was found as the difference between total iron (NAA) and blood iron ( 55 Fe). The activation analysis of the samples from the wound tissues was supposed to give information about the participation of other essential trace elements in wound healing. In the framework of the development of new cancer chemotherapeutics with a specific effect on hormone-dependent mammary carcinoma, the distribution of the respective medications in tumor tissues and organs of rats and mice based on the activation analysis determination of platinum content in tissues of interest was ascertained. In the activation analyses for platinum determination the amounts in the samples of other essential trace elements was also determined, in order to ascertain characteristic accumulation or reduction of trace elements in various tissues as a result of tumor development or in connection with therapy. (orig./MG) [de

Platinum Group Metal Recycling Technology Development - Final Report

Energy Technology Data Exchange (ETDEWEB)

Lawrence Shore

2009-08-19

BASF Catalysts LLC, formerly Engelhard Corporation, has completed a project to recover Pt from PEM fuel cell membrane electrode assemblies. The project, which began in 2003, has met the project objective of an environmentally-friendly, cost-effective method for recovery of platinum without release of hydrogen fluoride. This has been achieved using a combination of milling, dispersion and acid leaching. 99% recovery of Pt was achieved, and this high yield can be scaled up using one vessel for a single leach and rinse. Leaching was been successfully achieved using a 10% solids level, double the original target. At this solids content, the reagent and utility costs represent ~0.35% of the Pt value of a lot, using very conservative assumptions. The main cost of the process is capital depreciation, followed by labor.

Gas chromatographic--mass spectrometric quantitation of 16, 16-dimethyl-trans-delta 2-PGE1

Energy Technology Data Exchange (ETDEWEB)

Dimov, V.; Green, K.; Bygdeman, M.; Konishi, Y.; Imaki, K.; Hayashi, M.

1983-02-01

Di-deuterated and di-tritiated 16,16-dimethyl-trans-delta 2-PGE1 has been synthesized and used for development of a GC-MS method for quantitation of corresponding unlabelled drug in patient plasma. Although these carrier/internal standard molecules only contain 2 deuterium atoms the lower limit of detection at each injection is as low as about 40 pg. The maximum plasma levels of this drug following administration of vaginal suppositories used in clinical studies (1 mg 16,16-dimethyl-trans-delta 2-PGE1 methyl ester in 0.8 g Witepsol S-52) were 100-350 pg/ml i.e. in the same order of magnitude as earlier seen for 16,16-dimethyl-PGE2.

Gas chromatographic--mass spectrometric quantitation of 16, 16-dimethyl-trans-delta 2-PGE1

International Nuclear Information System (INIS)

Dimov, V.; Green, K.; Bygdeman, M.; Konishi, Y.; Imaki, K.; Hayashi, M.

1983-01-01

Di-deuterated and di-tritiated 16,16-dimethyl-trans-delta 2-PGE1 has been synthesized and used for development of a GC-MS method for quantitation of corresponding unlabelled drug in patient plasma. Although these carrier/internal standard molecules only contain 2 deuterium atoms the lower limit of detection at each injection is as low as about 40 pg. The maximum plasma levels of this drug following administration of vaginal suppositories used in clinical studies (1 mg 16,16-dimethyl-trans-delta 2-PGE1 methyl ester in 0.8 g Witepsol S-52) were 100-350 pg/ml i.e. in the same order of magnitude as earlier seen for 16,16-dimethyl-PGE2

Reactions of neopentane and neohexane on platinum/Y-zeolite and platinum/silica catalysts

Energy Technology Data Exchange (ETDEWEB)

Foger, K.; Anderson, J.R.

1978-10-13

The hydrocracking/hydroisomerization reaction of 20:1 hydrogen/neopentane at 455-625/sup 0/K was studied on platinum-exchanged sodium, calcium, and lanthanum Y zeolites and Aerosil-supported platinum of 1-20 nm average platinum particle size, by analysis of the product distribution, ESCA, and temperature-programed desorption. The results suggested that the reaction occurs only on platinum and that it proceeds by two parallel pathways which have different activation energies and whose relative proportion depends on the particle size. One pathway is the conventionally accepted one on low-index crystallite facets; the other proceeds on single-surface platinum atoms of low coordination (corner or edge atoms) which become more abundant at lower crystallite size. In both cases, the adsorbed intermediate may undergo either isomerization or hydrogenolysis; the selectivity depends on the hydrogen partial pressure and the relative strength of adsorption of hydrogen and neopentane. Neohexane isomerization selectivity on the same catalysts is consistent with a carbonium ion mechanism on a dual-function catalyst.

Impurities determination in precious metals like rhodium, palladium and platinum by neutron activation without separation

International Nuclear Information System (INIS)

May, S.; Piccot, D.; Pinte, G.

1978-01-01

The possibilities of the method explored using an installation of gamma or X ray spectrometry of good performance. The irradiations were realized in the reactors EL.3 (flux approximately 6.10 12 n.cm -2 .s -1 ) and Osiris (flux > 10 14 n.cm -2 .s -1 ) of the CEN Saclay. In rhodium the presence of iridium limits the analysis possibilities. However gold, silver and platinum are easily determined, just as the other elements (As, Br, Cl, Co, Mn, Na, Sb). In platinum it is possible to determine the elements of long period, especially antimony, silver, cobalt, iridium, tantalum and zinc. As for palladium the principal impurities are gold, silver and ruthenium for what is of precious metals and particularly zinc among the other metals. For the three matrices considered the detection limits of a certain number of elements are indicated [fr

Suppression of the cutaneous immune response following topical application of the prostaglandin PGE2

International Nuclear Information System (INIS)

Rheins, L.A.; Barnes, L.; Amornsiripanitch, S.; Collins, C.E.; Nordlund, J.J.

1987-01-01

UVB irradiation (290-320 nm) and topical applications of arachidonic acid (AA) in mice decrease the number of identifiable Langerhans cells and alter the cutaneous immune response. Application of contact allergens such as dinitrofluorobenzene (DNFB) to irradiated or AA-treated skin induces antigen-specific tolerance. Indomethacin (IM), a cyclooxygenase inhibitor, administered orally to mice prior to UVB irradiation or prior to the topical application of arachidonic acid, abrogates suppression of contact hypersensitivity (CHS) to DNFB. This suggests a byproduct of arachidonic acid generated through the cyclooxygenase pathway may be involved in the immune suppression. Topical application of various prostaglandins (PGE2, PGD2, PGF2 alpha, and CTXA2) did not cause alterations in the population density of the identifiable Ia+ dendritic Langerhans cells. PGE2, but no other tested agent, produced a suppression of the CHS response to DNFB. These observations suggests that of the various prostaglandins, PGE2 might be one of several biochemical signals which mediate the suppression of contact hypersensitivity reactions following ultraviolet radiation exposure. However, the mechanisms by which PGE2 produces its suppressive effects have not been identified

Hydrogenation of hexene over platinum on alumina vs. platinum in a Na-Y zeolite

International Nuclear Information System (INIS)

Miner, R.S. Jr.; Ione, K.G.; Namba, S.; Turkevich, J.

1978-01-01

In order to study the efficacy of zeolites as supports, several platinum H--Y zeolites were prepared by ion exchanging an H--Y zeolite with Pt(NH 3 ) 4 Cl 2 and reducing these products with hydrazine hydrate (A, B, C). Another preparation was made by adsorbing 32-A platinum sol on the zeolite crystallites (D). These catalysts were studied for hydrogenation and isomerization of hexene-1, ethylene hydrogenation, hydrogen chemisorption, and poison titration. They were compared with monodisperse Pt (32 A diameter) on alumina. A marked difference was found between the behavior of hexene-1 with the platinum-in-zeolite and with the platinum-on-alumina

Proneoplastic effects of PGE2 mediated by EP4 receptor in colorectal cancer.

LENUS (Irish Health Repository)

Doherty, Glen A

2009-01-01

BACKGROUND: Prostaglandin E2 (PGE2) is the major product of Cyclooxygenase-2 (COX-2) in colorectal cancer (CRC). We aimed to assess PGE2 cell surface receptors (EP 1-4) to examine the mechanisms by which PGE2 regulates tumour progression. METHODS: Gene expression studies were performed by quantitative RT-PCR. Cell cycle was analysed by flow cytometry with cell proliferation quantified by BrdU incorporation measured by enzyme immunoassay. Immunohistochemistry was employed for expression studies on formalin fixed paraffin embedded tumour tissue. RESULTS: EP4 was the most abundant subtype of PGE2 receptor in HT-29 and HCA7 cells (which show COX-2 dependent PGE2 generation) and was consistently the most abundant transcript in human colorectal tumours (n = 8) by qRT-PCR (ANOVA, p = 0.01). G0\\/G1 cell cycle arrest was observed in HT-29 cells treated with SC-236 5 microM (selective COX-2 inhibitor) for 24 hours (p = 0.02), an effect abrogated by co-incubation with PGE2 (1 microM). G0\\/G1 arrest was also seen with a specific EP4 receptor antagonist (EP4A, L-161982) (p = 0.01). Treatment of HT-29 cells with either SC-236 or EP4A caused reduction in intracellular cAMP (ANOVA, p = 0.01). Early induction in p21WAF1\\/CIP1 expression (by qRT-PCR) was seen with EP4A treatment (mean fold increase 4.4, p = 0.04) while other genes remained unchanged. Similar induction in p21WAF1\\/CIP1 was also seen with PD153025 (1 microM), an EGFR tyrosine kinase inhibitor, suggesting EGFR transactivation by EP4 as a potential mechanism. Additive inhibition of HCA7 proliferation was observed with the combination of SC-236 and neutralising antibody to amphiregulin (AR), a soluble EGFR ligand. Concordance in COX-2 and AR localisation in human colorectal tumours was noted. CONCLUSION: COX-2 regulates cell cycle transition via EP4 receptor and altered p21WAF1\\/CIP1 expression. EGFR pathways appear important. Specific targeting of the EP4 receptor or downstream targets may offer a safer alternative

Minor elements in magnetic concentrates from the Syenite-Shonkinite Province, southern Asir, Kingdom of Saudi Arabia

Science.gov (United States)

Overstreet, W.C.; Day, G.W.; Botinelly, Theodore; VanTrump, George

1987-01-01

Magnetic concentrates from 106 localities in three plutons of syenite and one pluton of shonkinite in the southern Asir were analyzed spectrographically for 31 elements to determine if anomaly-enhancement techniques would identify mineralization not disclosed by conventional geochemical sample media. Positive anomalies are lacking for all elements except vanadium. Vanadium contents as high as 0.7 percent were identified in magnetic concentrates from the syenite pluton to the southeast of Suq al Ithnayn, but magnetite is sparse. This observation indicates a need to reexamine magnetite-rich drill core for possible ore-grade tenors in vanadium from the zoned pluton at Lakathah. Experimental analyses for platinum-group metals in magnetic concentrates from layered mafic plutons at Jabal Sha'i', Jabal al Ashshar, and Hishshat al Hawi should be performed to determine whether micron-size particles of the platinum-group metals are present in mafic rocks of the Arabian Shield.

BLOCKADE OF PGE2, PGD2 RECEPTORS CONFERS PROTECTION AGAINST PREPATENT SCHISTOSOMIASIS MANSONI IN MICE.

Science.gov (United States)

Abdel-Ghany, Rasha; Rabia, Ibrahim; El-Ahwany, Eman; Saber, Sameh; Gamal, Rasha; Nagy, Faten; Mahmoud, Olaa; Hamad, Rabab Salem; Barakat, Walled

2015-12-01

Schistosomiasis is a chronic disease with considerable social impact. Despite the availability of affordable chemotherapy, drug treatment has not significantly reduced the overall number of disease cases. Among other mechanisms, the parasite produces PGE2 and PGD2 to evade host immune defenses. To investigate the role of PGE2 and PGD2 in schistosomiasis, we evaluated the effects of L-161,982, Ah6809 (PGE2 receptor antagonists alone of combined with each other) and MK-0524 (PGD2 receptor antagonist) during prepatent Schistosoma mansoni infection. Drugs were administered intraperitoneally an hour before and 24 hours after infection of C57BL/6 mice with 100 Schistosoma mansoni cercariae. L-161,982, Ah6809, their combination and MK-0524 caused partial protection against pre-patent S. mansoni infection which was mediated by biasing the immune response towards Th1 phenotype. These results showed that blockade of PGE2 and PGD2 receptors confers partial protection against pre-patent S. mansoni infection in mice and that they may be useful as adjunctive therapy to current anti-schistosomal drugs or vaccines.

Phosphoric acid fuel cell platinum use study

Science.gov (United States)

Lundblad, H. L.

1983-05-01

The U.S. Department of Energy is promoting the private development of phosphoric acid fuel cell (PAFC) power plants for terrestrial applications. Current PAFC technology utilizes platinum as catalysts in the power electrodes. The possible repercussions that the platinum demand of PAFC power plant commercialization will have on the worldwide supply and price of platinum from the outset of commercialization to the year 2000 are investigated. The platinum demand of PAFC commercialization is estimated by developing forecasts of platinum use per unit of generating capacity and penetration of PAFC power plants into the electric generation market. The ability of the platinum supply market to meet future demands is gauged by assessing the size of platinum reserves and the capability of platinum producers to extract, refine and market sufficient quantities of these reserves. The size and timing of platinum price shifts induced by the added demand of PAFC commercialization are investigated by several analytical methods. Estimates of these price shifts are then used to calculate the subsequent effects on PAFC power plant capital costs.

Determination of platinum, palladium, iridium and gold on selected geological reference materials by radiochemical neutron activation analysis: comparison of procedures based on aqua regia leaching and sodium peroxide sintering

International Nuclear Information System (INIS)

Nogueira, C.A.; Figueiredo, A.M.G.

1995-01-01

A rapid and sensitive neutron activation method for the determination of platinum, palladium, iridium and gold in rocks is described. The procedure consists of thermal neutron irradiation of about 250 mg of sample, followed by chemical treatment of the rock, precipitation of gold and the platinum group elements with tellurium and high-resolution gamma-ray spectrometry with a hyper-pure Ge detector. Two different methods were used for the chemical treatment of the rock: aqua regia leaching and sintering with sodium peroxide. The procedures were evaluated by analysis of the certified reference material SARM-7 and the reference material CHR-Pt+. (author)

Determination of platinum, palladium, iridium and gold on selected geological reference materials by radiochemical neutron activation analysis: comparison of procedures based on aqua regia leaching and sodium peroxide sintering

Energy Technology Data Exchange (ETDEWEB)

Nogueira, C.A.; Figueiredo, A.M.G. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

1995-05-01

A rapid and sensitive neutron activation method for the determination of platinum, palladium, iridium and gold in rocks is described. The procedure consists of thermal neutron irradiation of about 250 mg of sample, followed by chemical treatment of the rock, precipitation of gold and the platinum group elements with tellurium and high-resolution gamma-ray spectrometry with a hyper-pure Ge detector. Two different methods were used for the chemical treatment of the rock: aqua regia leaching and sintering with sodium peroxide. The procedures were evaluated by analysis of the certified reference material SARM-7 and the reference material CHR-Pt+. (author).

Niraparib Maintenance Therapy in Platinum-Sensitive, Recurrent Ovarian Cancer

DEFF Research Database (Denmark)

Mirza, Mansoor R; Monk, Bradley J; Herrstedt, Jørn

2016-01-01

Background Niraparib is an oral poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) 1/2 inhibitor that has shown clinical activity in patients with ovarian cancer. We sought to evaluate the efficacy of niraparib versus placebo as maintenance treatment for patients with platinum-sensitive, ......Background Niraparib is an oral poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) 1/2 inhibitor that has shown clinical activity in patients with ovarian cancer. We sought to evaluate the efficacy of niraparib versus placebo as maintenance treatment for patients with platinum...... or 4 adverse events that were reported in the niraparib group were thrombocytopenia (in 33.8%), anemia (in 25.3%), and neutropenia (in 19.6%), which were managed with dose modifications. Conclusions Among patients with platinum-sensitive, recurrent ovarian cancer, the median duration of progression...

Cytotoxic evaluation upon cis-platinum aminodiacetic acid complexes

International Nuclear Information System (INIS)

Almah binti Awaluddin; Parsons, Peter G.; Lean, Jenny M.; Jacobs, Jeffrey J.

1990-01-01

Cytoxic study of cis-platinum aminodiacetic acid complexes. Three novel platinum complexes have been synthesised and characterised by Awaluddin et. al (1987). This introduces a new area of radiopharmaceuticals based on technician and platinum. Cytotoxic studies were conducted on these complexes using four different types of cell lines. The para amina was found to be highly active against multi-resistant ovarian tumor cells compared to normal cells (fibroblast) and other tumor cells. The chemical structure of para-amina appears to be devoid of any functional group resembling current antitumor drugs except for a distant similarity to metotrexate with respect to the p-aminobenzoic type structure. However cell lines such as Hela and MM 253c-1, which is sensitive to metotrexate, were not sensitive to the para amina. Preliminary studies have shown that cells are blocked in the G phase of the cell cycle, suggesting an antimetabolite effect

AMS-measurements of stable platinum isotopes in presolar nanodiamonds with the help of a negative-ion-injector for VERA

International Nuclear Information System (INIS)

Melber, K.

2011-01-01

The Vienna Environmental Research Accelerator (VERA) is a universal facility for Accelerator Mass Spectrometry (AMS). VERA is based on a 3-MV tandemaccelerator and enables one to investigate isotope ratios down to 10 -16 over the whole mass range of the elements. The main application is the measurement of long-lived radioisotopes of cosmogenic or anthropogenic origin (e.g. 10 Be, 14 C, 26 Al, 36 Cl, 41 Ca, 129 I, 236 U, 244 Pu). In principle it is also possible to detect stable isotopes of trace elements (Trace Element AMS: TEAMS). TEAMS is of particular interest with regard to so-called presolar grains in meteorites. Presolar grains contain trace elements whose isotope compositions differ substantially from those of our solar system. This points to a presolar origin of these grains. Among presolar grains, nanodiamonds are still poorly understood. They are composed of only a few thousand carbon atoms and contain platinum as one of the trace elements. There are still questions on their origin. E.g. were they 'doped' with the trace elements in the environment of a supernova? Which nucleosynthetic processes have taken place? Here the isotope signatures could deliver additional information. The aim of the present work was to establish conditions at VERA for the measurement of stable platinum isotopes in presolar nanodiamonds. The difficulty of such a measurement lies in the fact that trace analyses of stable Pt isotopes are only possible if the platinum background of the ion source is low. Hence, a new negative ion injector with a new sputtersource in which platinum was never used as a test material was build up at VERA. It was then possible to carry out Pt-isotope measurements in nanodiamonds for the first time. The sample material originates from the Allende-meteorite and was purified for nanodiamonds by the cosmochemistry group of the Max Planck Institute of Chemistry in Mainz. As a main result of the measurements it was possible to detect an access of the heaviest

Preliminary study of platinum accumulation in the fruitbodies of a model fungal species: king oyster mushroom (Pleurotus eryngii)

International Nuclear Information System (INIS)

Urban, P.L.; Bazala, M.A.; Bystrzejewska-Piotrowska, G.; Pianka, D.; Steborowski, R.; Asztemborska, M.; Kowalska, J.; Manjon, J.L.; Kuthan, R.T.

2005-01-01

A model species of saprophytic fungus, king oyster mushroom (Pleurotus eryngii), was cultivated on barley substrate supplied with [Pt(NH 3 ) 4 ](NO 3 ) 2 , under well defined conditions. The samples of the collected fruiting bodies were digested and analyzed for total platinum content by means of ICP-MS. The results proved that platinum is not accumulated in the fruitbodies of Pleurotus eryngii for a wide range of Pt concentrations in the culture substrate (100-1000 ppb Pt in 50 ml of water solution added to ca. 450 g of hydrated barley seeds per container). Observable levels of Pt were only found in the fruitbodies obtained from the medium contaminated with 10000 ppb (10 ppm) platinum solution. This demonstrates significant difference in the effectiveness of platinum extraction in fungi and plants, which are capable to accumulate platinum even when supplied at lower concentration (<500 ppb). It also shows different physiological pathways of platinum and other elements which are easily accumulated in the fruitbodies of the same species. (author)

Chemical reactions on platinum-group metal surfaces studied by synchrotron-radiation-based spectroscopy

International Nuclear Information System (INIS)

Kondoh, Hiroshi; Nakai, Ikuyo; Nagasaka, Masanari; Amemiya, Kenta; Ohta, Toshiaki

2009-01-01

A new version of synchrotron-radiation-based x-ray spectroscopy, wave-length-dispersive near-edge x-ray absorption fine structure (dispersive-NEXAFS), and fast x-ray photoelectron spectroscopy have been applied to mechanistic studies on several surface catalytic reactions on platinum-group-metal surfaces. In this review, our approach using above techniques to understand the reaction mechanism and actual application studies on three well-known catalytic surface reactions, CO oxidation on Pt(111) and Pd(111), NO reduction on Rh(111), and H 2 O formation on Pt(111), are introduced. Spectroscopic monitoring of the progress of the surface reactions enabled us to detect reaction intermediates and analyze the reaction kinetics quantitatively which provides information on reaction order, rate constant, pre-exponential factor, activation energy and etc. Such quantitative analyses combined with scanning tunneling microscopy and kinetic Monte Carlo simulations revealed significant contribution of the adsorbate configurations and their dynamic changes to the reaction mechanisms of the above fundamental catalytic surface reactions. (author)

Developments in platinum anticancer drugs

Science.gov (United States)

Tylkowski, Bartosz; Jastrząb, Renata; Odani, Akira

2018-01-01

Platinum compounds represent one of the great success stories of metals in medicine. Following the unexpected discovery of the anticancer activity of cisplatin (Fig. 1) in 1965 by Prof. Rosenberg [1], a large number of its variants have been prepared and tested for their ability to kill cancer cells and inhibit tumor growth. Although cisplatin has been in use for over four decades, new and more effective platinum-based therapeutics are finally on the horizon. A wide introduction to anticancer studies is given by the authors of the previous chapter. This chapter aims at providing the readers with a comprehensive and in-depth understanding of recent developments of platinum anticancer drugs and to review the state of the art. The chapter is divided into two parts. In the first part we present a historical aspect of platinum and its complexes, while in the second part we give an overview of developments in the field of platinum anticancer agents.

Hall Measurements on Carbon Nanotube Paper Modified With Electroless Deposited Platinum

Directory of Open Access Journals (Sweden)

Iwuoha Emmanuel

2009-01-01

Full Text Available Abstract Carbon nanotube paper, sometimes referred to as bucky paper, is a random arrangement of carbon nanotubes meshed into a single robust structure, which can be manipulated with relative ease. Multi-walled carbon nanotubes were used to make the nanotube paper, and were subsequently modified with platinum using an electroless deposition method based on substrate enhanced electroless deposition. This involves the use of a sacrificial metal substrate that undergoes electro-dissolution while the platinum metal deposits out of solution onto the nanotube paper via a galvanic displacement reaction. The samples were characterized using SEM/EDS, and Hall-effect measurements. The SEM/EDS analysis clearly revealed deposits of platinum (Pt distributed over the nanotube paper surface, and the qualitative elemental analysis revealed co-deposition of other elements from the metal substrates used. When stainless steel was used as sacrificial metal a large degree of Pt contamination with various other metals was observed. Whereas when pure sacrificial metals were used bimetallic Pt clusters resulted. The co-deposition of a bimetallic system upon carbon nanotubes was a function of the metal type and the time of exposure. Hall-effect measurements revealed some interesting fluctuations in sheet carrier density and the dominant carrier switched from N- to P-type when Pt was deposited onto the nanotube paper. Perspectives on the use of the nanotube paper as a replacement to traditional carbon cloth in water electrolysis systems are also discussed.

COST action TD1407: network on technology-critical elements (NOTICE)—from environmental processes to human health threats

OpenAIRE

Cobelo-García, A.; Filella, M.; Croot, P.; Frazzoli, C.; Du Laing, G.; Ospina-Alvarez, N.; Rauch, S.; Salaun, P.; Schäfer, J.; Zimmermann, S.

2015-01-01

The current socio-economic, environmental and public health challenges that countries are facing clearly need common-defined strategies to inform and support our transition to a sustainable economy. Here, the technology-critical elements (which includes Ga, Ge, In, Te, Nb, Ta, Tl, the Platinum Group Elements and most of the rare-earth elements) are of great relevance in the development of emerging key technologies—including renewable energy, energy efficiency, electronics or the aerospace ind...

Problems, possibilities and limitations of inductively coupled plasma atomic emission spectrometry in the determination of platinum, palladium and rhodium in samples with different matrix composition

Energy Technology Data Exchange (ETDEWEB)

Petrova, P.; Velichkov, S. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bontchev Str. bl. 11, 1113 Sofia (Bulgaria); Velitchkova, N. [Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bontchev Str., bl.24, 1113 Sofia (Bulgaria); Havezov, I. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bontchev Str. bl. 11, 1113 Sofia (Bulgaria); Daskalova, N., E-mail: das15482@svr.igic.bas.b [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bontchev Str. bl. 11, 1113 Sofia (Bulgaria)

2010-02-15

The economic and geological importance of platinum group of elements has led to the development of analytical methods to quantify them in different types of samples. In the present paper the quantitative information for spectral interference in radial viewing 40.68 MHz inductively coupled plasma atomic emission spectrometry in the determination of Pt, Pd and Rh in the presence of complex matrix, containing Al, Ca, Fe, Mg, Mn, P and Ti as matrix constituents was obtained. The database was used for optimum line selections. By using the selected analysis lines the following detection limits in ng g{sup -1} were obtained: Pt 1700, Pd-1440, Rh-900. The reached detection limits determine the possibilities and limitation of the direct ICP-AES method in the determination of Pt, Pd and Rh in geological and environmental materials. The database for spectral interferences in the presence of aluminum can be used for the determination of platinum group of elements in car catalysts. The accuracy of the analytical results was experimentally demonstrated by two certified reference materials that were analyzed: SARM 7, Pt ore and recycled auto-catalyst certified reference material SRM 2556.

Misoprostol, an anti-ulcer agent and PGE2 receptor agonist, protects against cerebral ischemia

OpenAIRE

Li, Jun; Liang, Xibin; Wang, Qian; Breyer, Richard M.; McCullough, Louise; Andreasson, Katrin

2008-01-01

Induction of COX-2 activity in cerebral ischemia results in increased neuronal injury and infarct size. Recent studies investigating neurotoxic mechanisms of COX-2 demonstrate both toxic and paradoxically protective effects of downstream prostaglandin receptor signaling pathways. We tested whether misoprostol, a PGE2 receptor agonist that is utilized clinically as an anti-ulcer agent and signals through the protective PGE2 EP2, EP3, and EP4 receptors, would reduce brain injury in the murine m...

Removal of platinum group metals contained in molten glass using copper

International Nuclear Information System (INIS)

Uruga, Kazuyoshi; Sawada, Kayo; Arita, Yuji; Enokida, Youichi; Yamamoto, Ichiro

2007-01-01

Removal of platinum group metals (PGMs) such as Pd, Ru, and RuO 2 from molten glass by using various amounts of liquid Cu was done as a basic study on a new vitrification process for a high-level radio-active waste. We prepared two types of borosilicate glasses containing PGMs and Cu, respectively. These glasses were mixed together and heated at 1,473 K for 4h in Ar atmosphere. More than 95% of Pd were removed as a spherical metal button composed of Pd-Cu alloy when Cu was added in an amount 0.5 times the weight of Pd. Nearly 95% of Ru was also removed as a spherical button with 2.5-5 times as much Cu addition as Ru in weight. Ruthenium oxide was reduced to metallic Ru by a reaction with Cu in the molten glass. The removal fraction was increased by increasing the amount of Cu and reached 63% when Cu addition was 7.5 times as much as RuO 2 in weight. By addition of Si as a reducing agent, nearly 90% of Pd and Ru were removed with Cu and Si metal composites even under O 2 :Ar=20:80 (v/v) condition. (author)

The Nokomis Cu-Ni-PGE Deposit, Duluth Complex: A sulfide-bearing, crystal-laden magmatic slurry

Science.gov (United States)

Peterson, D. M.

2009-12-01

Duluth Metals Limited’s Nokomis deposit is the most recently discovered Cu-Ni-PGE deposit in the 1.1 Ga. Duluth Complex, Minnesota. The deposit was discovered utilizing a genetic ore deposit model that identified and back-tracked channelized magma flow within the basal zone of the South Kawishiwi intrusion (SKI). The model led to exploratory drilling in 2006, deposit discovery and initial resource estimation in 2007, and significant resource expansion in 2008, all in a period of 18 months. The deposit’s updated 2008 NI 43-101 compliant Resource Estimate, based on 108 holes drilled by Duluth Metals and 52 historic drill holes on and off the property, contains 449 million tonnes of Indicated Resources grading 0.624% copper, 0.199% nickel, and 0.600 grams per tonne of total precious metals (TPM = Platinum+Palladium+Gold), and an additional 284 million tonnes of Inferred Resources grading 0.627% copper, 0.194% nickel, and 0.718 grams per tonne of TPM. The combined Indicated and Inferred Resources contain approximately 10 billion lbs Cu, 3.1 billion lbs Ni, 165 million lbs Co, 4 million ounces Pt, 9 million ounces Pd, and 2 million ounces of Au. Within these NI 43-101 resources are large tonnages of higher grade material, and the company has commenced an internal research program to identify the geologic controls on the formation nickel-rich and PGE-rich mineralization in the SKI, as well as copper-PGE rich mineralization in the footwall Archean rocks. To date, Duluth Metals has drilled more than 500,000 Ft. (~155,000 m) of core in 155 holes into the deposit, and has only drilled about half of the property. The ore deposit model was developed in cooperation with researchers from the Natural Resources Research Institute of the University of Minnesota, Duluth. As well, research and collaboration with faculty and students at Johns Hopkins University on the Ferrar Dolerites of the Antarctic Dry Valleys has played a key role in developing the magmatic model for the

Regulation of insulin-like growth factor I transcription by cyclic adenosine 3',5'-monophosphate (cAMP) in fetal rat bone cells through an element within exon 1: protein kinase A-dependent control without a consensus AMP response element

Science.gov (United States)

McCarthy, T. L.; Thomas, M. J.; Centrella, M.; Rotwein, P.

1995-01-01

Insulin-like growth factor I (IGF-I) is a locally synthesized anabolic growth factor for bone. IGF-I synthesis by primary fetal rat osteoblasts (Ob) is stimulated by agents that increase the intracellular cAMP concentration, including prostaglandin E2 (PGE2). Previous studies with Ob cultures demonstrated that PGE2 enhanced IGF-I transcription through selective use of IGF-I promoter 1, with little effect on IGF-I messenger RNA half-life. Transient transfection of Ob cultures with an array of promoter 1-luciferase reporter fusion constructs has now allowed localization of a potential cis-acting promoter element(s) responsible for cAMP-stimulated gene expression to the 5'-untranslated region (5'-UTR) of IGF-I exon 1, within a segment lacking a consensus cAMP response element. Our evidence derives from three principal observations: 1) a transfection construct containing only 122 nucleotides (nt) of promoter 1 and 328 nt of the 5'-UTR retained full PGE2-stimulated reporter expression; 2) maximal PGE2-driven reporter expression required the presence of nt 196 to 328 of exon 1 when tested within the context of IGF-I promoter 1; 3) cotransfection of IGF-I promoter-luciferase-reporter constructs with a plasmid encoding the alpha-isoform of the catalytic subunit of murine cAMP-dependent protein kinase (PKA) produced results comparable to those seen with PGE2 treatment, whereas cotransfection with a plasmid encoding a mutant regulatory subunit of PKA that cannot bind cAMP blocked PGE2-induced reporter expression. Deoxyribonuclease I footprinting of the 5'-UTR of exon 1 demonstrated protected sequences at HS3A, HS3B, and HS3D, three of six DNA-protein binding sites previously characterized with rat liver nuclear extracts. Of these three regions, only the HS3D binding site is located within the functionally identified hormonally responsive segment of IGF-I exon 1. These results directly implicate PKA in the control of IGF-I gene transcription by PGE2 and identify a segment of

Prostaglandin PGE2: a possible mechanism for bone destruction in calcinosis circumscripta.

Science.gov (United States)

Caniggia, A; Gennari, C; Vattimo, A; Runci, F; Bombardieri, S

1978-02-28

A patient showed evident osteolysis in phalanges and heavy periarticular calcium deposits of the fingers, wrists and toes which avidly took up 47Ca. The dense, white, tooth-paste like fluid contained in the periarticular calcium deposits has been studied by two different X-ray diffraction methods, by Ubatuba's bioassay for prostaglandin, by thin layer chromatography and by mass spectrometry. The calcium deposits were hydroxyapatite and prostaglandin PGE2 was detected in them. The bone resorption stimulating activity of PGE2 would be expected to result in increased bone destruction with release of calcium salts and this could be a working hypothesis of the pathogenesis of calcinosis circumscripta.

Novel non-platinum metal catalyst material

DEFF Research Database (Denmark)

2014-01-01

The present invention relates to a novel non-platinum metal catalyst material for use in low temperature fuel cells and electrolysers and to fuel cells and electrolysers comprising the novel non-platinum metal catalyst material. The present invention also relates to a novel method for synthesizing...... the novel non-platinum metal catalyst material....

Design, synthesis and anticancer activity of diam(m)ine platinum(II) complexes bearing a small-molecular cell apoptosis inducer dichloroacetate.

Science.gov (United States)

Liu, Weiping; Jiang, Jing; Xu, Yongping; Hou, Shuqian; Sun, Liping; Ye, Qingsong; Lou, Liguang

2015-05-01

Four new diam(m)ine platinum complexes containing the dichloroacetate moiety in 3-dichoroacetoxylcyclobutane-1,1-dicarboxylate as the leaving group were synthesized, characterized by elemental analysis as well as by ESI(+)-MS (electrospray ionization mass spectrometry in positive mode), FT-IR, (1)H- and (13)C-NMR, and evaluated for their in vitro anticancer activity against human lung cancer cell line (A549) and ovarian cancer cell lines (SK-OV-3, SK-OV-3/DDP). Diam(m)ines used in the present study belong to the carriers of six clinically approved platinum drugs. Among the complexes synthesized, complex 2, cis-[Pt(II)(1R,2R-diaminocyclohexane)·(3-dichoroacetoxylcyclobutane-1,1-dicarboxylate)] is the most promising in terms of water solubility and potential of being totally devoid of cross-drug resistance with cisplatin. Therefore, complex 2 was selected for the dichloroacetate release test. The test shows dichloroacetate can be efficiently released from complex 2 under physiological conditions via the hydrolysis of an ester bond bridging the dichloroacetate moiety and platinum pharmacophores together. Our study supports the further evaluation of this complex as a drug candidate. Copyright © 2015 Elsevier Inc. All rights reserved.

High Performance Platinum Group Metal Free Membrane Electrode Assemblies through Control of Interfacial Processes

Energy Technology Data Exchange (ETDEWEB)

Ayers, Katherine [Proton Energy Systems, Wallingford, CT (United States); Capuano, Christopher [Proton Energy Systems, Wallingford, CT (United States); Atanassov, Plamen [Univ. of New Mexico, Albuquerque, NM (United States); Mukerjee, Sanjeev [Northeastern Univ., Boston, MA (United States); Hickner, Michael [Pennsylvania State Univ., University Park, PA (United States)

2017-11-29

The quantitative goal of this project was to produce a high-performance anion exchange membrane water electrolyzer (AEM-WE) completely free of platinum group metals (PGMs), which could operate for at least 500 hours with less than 50 microV/hour degradation, at 500 mA/cm². To achieve this goal, work focused on the optimization of electrocatalyst conductivity, with dispersion and utilization in the membrane electrode assembly (MEA) improved through refinement of deposition techniques. Critical factors were also explored with significant work undertaken by Northeastern University to further understand catalyst-membrane-ionomer interfaces and how they differ from liquid electrolyte. Water management and optimal cell operational parameters were established through the design, fabrication, and test of a new test station at Proton specific for AEM evaluation. Additionally, AEM material stability and robustness at high potentials and gas evolution conditions were advanced at Penn State.

Does PGE1 Vasodilator Prevent Orthopaedic Implant-Related Infection in Diabetes? Preliminary Results in a Mouse Model

Science.gov (United States)

Lovati, Arianna B.; Romanò, Carlo L.; Monti, Lorenzo; Vassena, Christian; Previdi, Sara; Drago, Lorenzo

2014-01-01

Background Implant-related infections are characterized by bacterial colonization and biofilm formation on the prosthesis. Diabetes represents one of the risk factors that increase the chances of prosthetic infections because of related severe peripheral vascular disease. Vasodilatation can be a therapeutic option to overcome diabetic vascular damages and increase the local blood supply. In this study, the effect of a PGE1 vasodilator on the incidence of surgical infections in diabetic mice was investigated. Methodology A S. aureus implant-related infection was induced in femurs of diabetic mice, then differently treated with a third generation cephalosporin alone or associated with a PGE1 vasodilator. Variations in mouse body weight were evaluated as index of animal welfare. The femurs were harvested after 28 days and underwent both qualitative and quantitative analysis as micro-CT, histological and microbiological analyses. Results The analysis performed in this study demonstrated the increased host response to implant-related infection in diabetic mice treated with the combination of a PGE1 and antibiotic. In this group, restrained signs of infections were identified by micro-CT and histological analysis. On the other hand, the diabetic mice treated with the antibiotic alone showed a severe infection and inability to successfully respond to the standard antimicrobial treatment. Conclusions The present study revealed interesting preliminary results in the use of a drug combination of antibiotic and vasodilator to prevent implant-related Staphylococcus aureus infections in a diabetic mouse model. PMID:24718359

Evidence of Increased Anthropogenic Emissions of Platinum in Coastal Systems from Time-Series Analysis of Mussels Samples (1991-2011

Directory of Open Access Journals (Sweden)

Patricia Neira Del Río

2014-06-01

Full Text Available The Platinum Group Elements (PGEs, which include platinum (Pt, palladium (Pd, iridium (Ir, rhodium (Rh, osmium (Os and ruthenium (Ru, are amongst the rarest trace elements in the Earth’s crust. They have similar physical and chemical properties, and tend to occur together in the same mineral deposits. Their properties are resistance to chemical corrosion over a wide temperature range, high melting point, high mechanical strength and good ductility, as well as outstanding catalytic properties, being therefore critical in many emerging technologies. Although natural environmental concentrations of PGEs are extremely low – generally at or below the ng/g –, levels of Pt, Pd and Rh are increasing, mainly because of their use in catalytic converters of motor vehicles (Zereini et al., 2007. The automobile catalysts converters use noble metals as active components, and were developed with the aim of reducing emissions of hydrocarbons, carbon monoxide and nitrogen oxides (Sures et al., 2005. Since the beginning of the 1980s, the PGEs represent a relatively new category of trace metals in the environment, especially in relation to automobile traffic (Haus et al., 2007. The PGEs of automobile catalytic converters are eroded from the surface of the catalyst and subsequently emitted in metallic form or as oxides (Turner and Price, 2008. The PGEs are subject to various physical and chemical transformations after deposition, and can potentially result in migration into environmental compartments (Moldovan et al., 2001; Vaughan and Florence, 1992. The concentration of PGEs has much increased in traffic exposed environmental samples (Lesniewska et al., 2004; Ely et al., 2001; Zereini et al., 2001; Schäfer et al., 1999; Fritsche and Meisel, 2004. However, what constituted a decrease in greenhouse gas emissions has resulted in increased levels of PGEs in the environment as shown in some studies in the dust of the road, roadsides, river sediments, sewage

Redox reactions for group 5 elements, including element 105, in aqueous solutions

International Nuclear Information System (INIS)

Ionova, G.V.; Pershina, V.; Johnson, E.; Fricke, B.; Schaedel, M.

1992-08-01

Standard redox potentials Edeg(M z+x /M z+ ) in acidic solutions for group 5 elements including element 105 (Ha) and the actinide, Pa, have been estimated on the basis of the ionization potentials calculated via the multiconfiguration Dirac-Fock method. Stability of the pentavalent state was shown to increase along the group from V to Ha, while that of the tetra- and trivalent states decreases in this direction. Our estimates have shown no extra stability of the trivalent state of hahnium. Element 105 should form mixed-valence complexes by analogy with Nb due to the similar values of their potentials Edeg(M 3+ /M 2+ ). The stability of the maximum oxidation state of the elements decreases in the direction 103 > 104 > 105. (orig.)

PGE mineralization and melt composition of chromitites in Proterozoic ophiolite complexes of Eastern Sayan, Southern Siberia

Directory of Open Access Journals (Sweden)

O. Kiseleva

2017-07-01

Full Text Available The Ospino-Kitoi and Kharanur ultrabasic massifs represent the northern and southern ophiolite branches respectively of the Upper Onot ophiolitic nappe and they are located in the southeastern part of the Eastern Sayan (SEPES ophiolites. Podiform chromitites with PGE mineralization occur as lensoid pods within dunites and rarely in harzburgites or serpentinized peridotites. The chromitites are classified into type I and type II based on their Cr#. Type I (Cr# = 59–85 occurs in both northern and southern branches, whereas type II (Cr# = 76–90 occurs only in the northern branch. PGE contents range from ∑PGE 88–1189 ppb, Pt/Ir 0.04–0.42 to ∑PGE 250–1700 ppb, Pt/Ir 0.03–0.25 for type I chromitites of the northern and southern branches respectively. The type II chromitites of the northern branch have ∑PGE contents higher than that of type I (468–8617 ppb, Pt/Ir 0.1–0.33. Parental melt compositions, in equilibrium with podiform chromitites, are in the range of boninitic melts and vary in Al2O3, TiO2 and FeO/MgO contents from those of type I and type II chromitites. Calculated melt compositions for type I chromitites are (Al2O3melt = 10.6–13.5 wt.%, (TiO2melt = 0.01–0.44 wt.%, (Fe/Mgmelt = 0.42–1.81; those for type II chromitites are: (Al2O3melt = 7.8–10.5 wt.%, (TiO2melt = 0.01–0.25 wt.%, (Fe/Mgmelt = 0.5–2.4. Chromitites are further divided into Os-Ir-Ru (I and Pt-Pd (II based on their PGE patterns. The type I chromitites show only the Os-Ir-Ru pattern whereas type II shows both Os-Ir-Ru and Pt-Pd patterns. PGE mineralization in type I chromitites is represented by the Os-Ir-Ru system, whereas in type II it is represented by the Os-Ir-Ru-Rh-Pt system. These results indicate that chromitites and PGE mineralization in the northern branch formed in a suprasubduction setting from a fluid-rich boninitic melt during active subduction. However, the chromitites and PGE mineralization of the southern

Novel platinum black electroplating technique improving mechanical stability.

Science.gov (United States)

Kim, Raeyoung; Nam, Yoonkey

2013-01-01

Platinum black microelectrodes are widely used as an effective neural signal recording sensor. The simple fabrication process, high quality signal recording and proper biocompatibility are the main advantages of platinum black microelectrodes. When microelectrodes are exposed to actual biological system, various physical stimuli are applied. However, the porous structure of platinum black is vulnerable to external stimuli and destroyed easily. The impedance level of the microelectrode increases when the microelectrodes are damaged resulting in decreased recording performance. In this study, we developed mechanically stable platinum black microelectrodes by adding polydopamine. The polydopamine layer was added between the platinum black structures by electrodeposition method. The initial impedance level of platinum black only microelectrodes and polydopamine added microelectrodes were similar but after applying ultrasonication the impedance value dramatically increased for platinum black only microelectrodes, whereas polydopamine added microelectrodes showed little increase which were nearly retained initial values. Polydopamine added platinum black microelectrodes are expected to extend the availability as neural sensors.

[Labor induction with extra-amnial administration of PGE2 vaginal tablets].

Science.gov (United States)

Roztocil, A; Koudelka, M; Jelínek, J; Miklica, J; Pilka, L

1996-08-01

During the period between Jan. 1 1992 and Dec. 31, 1995 at the Second Department of Gynaecology and Obstetrics in Brno labour was induced in 1159 patients by extraamnial fractionated administration of PGE2 vaginal tablets. After assessment of the indication and the baseline examination (NST, amnioscopy, US biometry and cervical score) according to the CS to the patient the first dose of PGE2 was administered into the extraamnial space beyond the inner os uteri (CS 5-8:1.0 mg PGE2, CS > 8 : 0.5 mg PGE2). After two hours the patient was examined again and if regular uterine contractions had started or the finding on the os uteri was larger than 2 cm, the amniotic sac was disrupted. If not, another dose was administered. After two hours the patient was re-examined and if the os was larger than 2 cm, and there were regular uterine contractions, the amniotic sac was disrupted. If the changes did not take place, the induction was considered a failure. there were 1007 successful inductions (95.5%), the mean period from the onset of induction to the onset of uterine contractions was 180 mins.: 322 (29.5%). The mean period of the first stage of labour was 228 mins., stage II 10 mins., stage III 8 mins. Five times uterine hypertonus was recorded and a blood loss greater than 500 ml occurred in four patients. Forty-nine Caesarean sections were made (4.2%) and 51 (4.4%) forceps deliveries. The rate of epidural analgesia was 27 (2.3%). Revision of the uterine cavity was made in 39 patients (3.4%) and manual lysis of the placenta in 30 (2.6%). The Apgar score was inferior to 6 in 10 neonates (0.9%). The protocol of induction of labour described by the authors is effective and associated with a minimum of side-effects, safe for the mother and foetus, well tolerated by patients and cost-effective.

Problems connected with the production of highly specific antisera against prostaglandin E2 (PGE2) and prostaglandin A2 (PGA2) for radioimmunoassay

International Nuclear Information System (INIS)

Kopp, H.G.; Vetter, W.; Siegenthaler, W.

1978-01-01

To obtain sensitive and specific antisera against PGE 2 and PGA 2 these substances were coupled to thyroglobulin (Tg). Coupling reactions were performed by using either a hydroxy-succinimide-ester as intermediate step leading to a complex carrying 170mol PGE 2 per mol Tg (''PGE 2 -OSU-Tg'') and 240mol PGA 2 per mol Tg (''PGA 2 -OSU-Tg''), or N, N'-carbonyl-diimidazole resulting in ''PGE 2 -CDI-Tg'' (400mol PGE 2 per mol Tg) and ''PGA 2 -CDI-Tg'' (600mol PGA 2 per mol Tg). Two tracer systems ( 3 H-prostaglandin and 125 I-histamine-prostaglandin) were used for analysis of antibody activity. The PGE 2 -CDI-Tg and PGA 2 -CDI-Tg complexes were both poor immunogens in rabbits. The PGE 2 -OSU-Tg and PGA 2 -OSU-Tg conjugates were injected in rabbits and in guinea-pigs. These two compounds resulted in very high antibody titres in both animal species. However, in guinea-pigs a markedly higher antibody sensitivity and antibody specificity were observed than in rabbits. Our results indicate that the guinea-pig may be the animal of choice for immunization against prostaglandins. Antibody specificity of guinea-pig antisera may be high enough to measure the concentration of PGE 2 and PGA 2 in the presence of other prostaglandins or prostaglandin metabolites. (author)

Problems connected with the production of highly specific antisera against prostaglandin E2 (PGE2) and prostaglandin A2 (PGA2) for radioimmunoassay

International Nuclear Information System (INIS)

Kopp, H.G.; Vetter, W.; Siegenthaler, W.

1977-01-01

To obtain sensitive and specific antisera against PGE 2 and PGA 2 these substances were coupled to thyroglobulin (Tg). Coupling reactions were either performed by using a hydroxysuccinimideester as intermediate step leading to a complex carrying 170 mol PGE 2 per mol Tg ('PGE 2 -OSU-Tg') and 240 mol PGA 2 per mol Tg ('PGA 2 -OSU-Tg') or alternatively by using N,N'-carbonyl-diimidazole resulting in 'PGE 2 -CDI-Tg' (400 mol PGE 2 per mol Tg) and 'PGA 2 -CDI-Tg' (600 mol PGA 2 per mol Tg). Two tracer systems ( 3 H-prostaglandin, 125 I-histamine-prostaglandin) were used for analysis of antibody activity. Both PGE 2 - and PGA 2 -CDI-Tg complexes were poor immunogens in rabbits. The PGE 2 - and PGA 2 -OSU-Tg conjugates were injected both in rabbits and in guinea pigs. These two compounds resulted in very high antibody titers in both animal species. However, in guinea pigs markedly higher antibody sensitivity and antibody specificity were observed than in rabbits. Our results indicate that the guinea pig may be the animal of choice for immunization against prostaglandins. Antibody specificity of guinea pig antisera may be perhaps high enough to measure the concentration of PGE 2 and PGA 2 in the presence of other prostaglandins or prostaglandin metabolites. (orig.) [de

Oscillatory instabilities in the electrooxidation of borohydride on platinum

Energy Technology Data Exchange (ETDEWEB)

Machado, Eduardo G.; Varela, Hamilton, E-mail: varela@iqsc.usp.br [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Instituto de Quimica

2014-03-15

The borohydride ion has been pointed as a promising alternative fuel. Most of the investigation on its electrochemistry is devoted to the electrocatalytic aspects of its electrooxidation on platinum and gold surfaces. Besides the known kinetic limitations and intricate mechanism, our Group has recently found the occurrence of two regions of bi-stability and autocatalysis in the electrode potential during the open circuit interaction of borohydride and oxidized platinum surfaces. Following this previous contribution, the occurrence of more complicated phenomena is here presented: namely the presence of electrochemical oscillations during the electrooxidation of borohydride on platinum in alkaline media. Current oscillations were found to be associated to two distinct instability windows and characterized in the resistance-potential parameter plane. The dynamic features of such oscillations suggest the existence of distinct mechanisms according to the potential region. Previously published results obtained under non-oscillatory regime were used to give some hints on the surface chemistry behind the observed dynamics. (author)

BOWIEITE: A NEW RHODIUM-IRIDIUM-PLATINUM SULFIDE IN PLATINUM-ALLOY NUGGETS, GOODNEWS BAY, ALASKA.

Science.gov (United States)

Desborough, George A.; Criddle, Alan J.

1984-01-01

Bowieite (Rh,Ir,Pt)//2S//3, a new mineral species, is found in three nuggets of platinum from Goodnews Bay, Alaska. In linearly polarized reflected light, and compared to the host, higher reflecting white platinum-iridium alloy, bowieite is pale gray to pale gray-brown; neither bireflectance nor reflectance pleochroism is apparent. With polars crossed, its anisotropic rotation tints vary from gray to dark brown. Luminance values (relative to the CIE illuminant C) for R//1 and R//2, computed from full spectral data for the most bireflectant grain, are 45. 8% and 48. 2% in air, and 30. 5% and 33. 0% in oil, respectively. VHN//1//0//0 1288 (858 to 1635). Bowieite is orthorhombic, space group Pnca, with a 8. 454(7) -8. 473(8), b 5. 995(1)-6. 002(7), c 6. 143(1)-6. 121(8) A, Z equals 4. Some grains that are 2. 6 to 3. 8 atomic % metal-deficient occur as an optically coherent rim on bowieite; the rim and the bowieite grain are not optically continuous.

Multistage electrodeposition of supported platinum-based nanostructured systems for electrocatalytic applications

CSIR Research Space (South Africa)

Mkwizu, TS

2011-05-01

Full Text Available .R. Modibedi and Mkhulu K. Mathe* *kmathe@csir.co.za 219th ECS Meeting, 1 ? 6 May, 2011, Montreal, Canada Multistage Electrodeposition of Supported Platinum-based Nanostructured Systems for Electrocatalytic Applications Overview ? Acknowledgements... of constituent elements of the given electrode surface. ? Applications areas: Fuel cells, electrochemical sensors, electrolyzers Introduction e- A B 5 Introduction Atomic-level processes during electrocatalysis www...

PGE2 maintains self-renewal of human adult stem cells via EP2-mediated autocrine signaling and its production is regulated by cell-to-cell contact.

Science.gov (United States)

Lee, Byung-Chul; Kim, Hyung-Sik; Shin, Tae-Hoon; Kang, Insung; Lee, Jin Young; Kim, Jae-Jun; Kang, Hyun Kyoung; Seo, Yoojin; Lee, Seunghee; Yu, Kyung-Rok; Choi, Soon Won; Kang, Kyung-Sun

2016-05-27

Mesenchymal stem cells (MSCs) possess unique immunomodulatory abilities. Many studies have elucidated the clinical efficacy and underlying mechanisms of MSCs in immune disorders. Although immunoregulatory factors, such as Prostaglandin E2 (PGE2), and their mechanisms of action on immune cells have been revealed, their effects on MSCs and regulation of their production by the culture environment are less clear. Therefore, we investigated the autocrine effect of PGE2 on human adult stem cells from cord blood or adipose tissue, and the regulation of its production by cell-to-cell contact, followed by the determination of its immunomodulatory properties. MSCs were treated with specific inhibitors to suppress PGE2 secretion, and proliferation was assessed. PGE2 exerted an autocrine regulatory function in MSCs by triggering E-Prostanoid (EP) 2 receptor. Inhibiting PGE2 production led to growth arrest, whereas addition of MSC-derived PGE2 restored proliferation. The level of PGE2 production from an equivalent number of MSCs was down-regulated via gap junctional intercellular communication. This cell contact-mediated decrease in PGE2 secretion down-regulated the suppressive effect of MSCs on immune cells. In conclusion, PGE2 produced by MSCs contributes to maintenance of self-renewal capacity through EP2 in an autocrine manner, and PGE2 secretion is down-regulated by cell-to-cell contact, attenuating its immunomodulatory potency.

Molecular clusters of the main group elements

CERN Document Server

Driess, Matthias

2008-01-01

""To summarize, Molecular Clusters of the Main Group Elements is certainly not a popular science book, nor is it a textbook; it is a very good, up-to-date collection of articles for the specialist. Als Fazit bleibt: Molecular Clusters of the Main Group Elements ist sicher kein populissenschaftliches Werk, auch kein Lehrbuch, aber eine gelungene, hoch aktuelle Zusammenstellung fen interessierten Fachmann."" -Michael Ruck, TU Dresden, Angewandte Chemie, 2004 - 116/36 + International Edition 2004 - 43/36

C14–22 n-Alkanes in Soil from the Freetown Layered Intrusion, Sierra Leone: Products of Pt Catalytic Breakdown of Natural Longer Chain n-Alkanes?

Directory of Open Access Journals (Sweden)

John F. W. Bowles

2018-03-01

Full Text Available Soil above a platinum-group element (PGE-bearing horizon within the Freetown Layered Intrusion, Sierra Leone, contains anomalous concentrations of n-alkanes (CnH2n+2 in the range C14 to C22 not readily attributable to an algal or lacustrine origin. Longer chain n-alkanes (C23 to C31 in the soil were derived from the breakdown of leaf litter beneath the closed canopy humid tropical forest. Spontaneous breakdown of the longer chain n-alkanes to form C14–22 n-alkanes without biogenic or abiogenic catalysts is unlikely as the n-alkanes are stable. In the Freetown soil, the catalytic properties of the PGE (Pt in particular may lower the temperature at which oxidation of the longer chain n-alkanes can occur. Reaction between these n-alkanes and Pt species, such as Pt2+(H2O2(OH2 and Pt4+(H2O2(OH4 can bend and twist the alkanes, and significantly lower the Heat of Formation. Microbial catalysis is a possibility. Since a direct organic geochemical source of the lighter n-alkanes has not yet been identified, this paper explores the theoretical potential for abiogenic Pt species catalysis as a mechanism of breakdown of the longer n-alkanes to form C14–22 alkanes. This novel mechanism could offer additional evidence for the presence of the PGE in solution, as predicted by soil geochemistry.

Human mesenchymal stem cell proliferation is regulated by PGE2 through differential activation of cAMP-dependent protein kinase isoforms

International Nuclear Information System (INIS)

Kleiveland, Charlotte Ramstad; Kassem, Moustapha; Lea, Tor

2008-01-01

The conditions used for in vitro differentiation of hMSCs contain substances that affect the activity and expression of cyclooxygenase enzymes (COX1/COX2) and thereby the synthesis of prostanoids. hMSC constitutively produce PGE2 when cultivated in vitro. In this study we have investigated effects of PGE2 on proliferation of hMSC. We here demonstrate that one of the main control molecules in the Wnt pathway, GSK-3β, is phosphorylated at the negative regulatory site ser-9 after treating the cells with PGE2. This phosphorylation is mediated by elevation of cAMP and subsequent activation of PKA. Furthermore, PGE2 treatment leads to enhanced nuclear translocation of β-catenin, thus influencing cell proliferation. The presence of two PKA isoforms, types I and II, prompted us to investigate their individual contribution in PGE2-mediated regulation of proliferation. Specific activation of PKA type II with synthetic cAMP analogues, resulted in enhancement of proliferation. On the other side, we found that treatment of hMSC with high concentrations of PGE2 inhibited cell proliferation by arresting the cells in G 0 /G 1 phase, an effect we found to be mediated by PKA I. Hence, the two different PKA isoforms seem to have opposing functions in the regulation of proliferation and differentiation in these cells

Low platinum catalyst and method of preparation

Energy Technology Data Exchange (ETDEWEB)

Liu, Di-Jia; Chong, Lina

2017-11-21

A low platinum catalyst and method for making same. The catalyst comprises platinum-transition metal bimetallic alloy microcrystallites over a transition metal-nitrogen-carbon composite. A method of making a catalyst comprises preparation of transition metal organic frameworks, infusion of platinum, thermal treatment, and reduction to form the microcrystallites and composite.

Redeposition of electrochemically dissolved platinum as nanoparticles on carbon

DEFF Research Database (Denmark)

Norgaard, C. F.; Stamatin, S. N.; Skou, E. M.

2014-01-01

communication reports a simple chemical method for reprecipitating platinum as nanoparticles of reasonable particle size on a carbon substrate without intermediary separation and handling of solid platinum salt. After electrochemical dissolution, platinum was reprecipitated using a polyol based method. Platinum...

Rapid and Efficient Collection of Platinum from Karstedt's Catalyst Solution via Ligands-Exchange-Induced Assembly.

Science.gov (United States)

Yang, Gonghua; Wei, Yanlong; Huang, Zhenzhu; Hu, Jiwen; Liu, Guojun; Ou, Ming; Lin, Shudong; Tu, Yuanyuan

2018-02-21

Reported herein is a novel strategy for the rapid and efficient collection of platinum from Karstedt's catalyst solution. By taking advantage of a ligand-exchange reaction between alkynols and the 1,3-divinyltetramethyldisiloxane ligand (M Vi M Vi ) that coordinated with platinum (Pt(0)), the Karstedt's catalyst particles with a size of approximately 2.5 ± 0.7 nm could be reconstructed and assembled into larger particles with a size of 150 ± 35 nm due to the hydrogen bonding between the hydroxyl groups of the alkynol. In addition, because the silicone-soluble M Vi M Vi ligand of the Karstedt's catalyst was replaced by water-soluble alkynol ligands, the resultant large particles were readily dispersed in water, resulting in rapid, efficient, and complete collection of platinum from the Karstedt's catalyst solutions with platinum concentrations in the range from ∼20 000 to 0.05 ppm. Our current strategy not only was used for the rapid and efficient collection of platinum from the Karstedt's catalyst solutions, but it also enabled the precise evaluation of the platinum content in the Karstedt's catalysts, even if this platinum content was extremely low (i.e., 0.05 ppm). Moreover, these platinum specimens that were efficiently collected from the Karstedt's catalyst solutions could be directly used for the evaluation of platinum without the need for pretreatment processes, such as calcination and digestion with hydrofluoric acid, that were traditionally used prior to testing via inductively coupled plasma mass spectrometry in conventional methods.

Exposure of the German general population to platinum and rhodium - Urinary levels and determining factors.

Science.gov (United States)

Munker, Sven; Kilo, Sonja; Röß, Christoph; Jeitner, Peter; Schierl, Rudolf; Göen, Thomas; Drexler, Hans

2016-11-01

In this study the exposure of the general population in Germany to platinum and rhodium and its determinants was investigated in 259 participants (subdivided in three groups) by urine analyses and assessment of the dental status. Complementary, an interview including questions characterising possible exposure to traffic exhaust was conducted. The median excretion was 2.42ng platinum/g creatinine and 7.27ng rhodium/g creatinine. The detailed analysis of the collected data showed significant higher platinum excretion values with increasing number of surfaces covered with restorations containing precious metals (R=0.389; prhodium excretion values (median=7.27ng/g; 95th percentile=13.5 ng/g). In summary, the study showed that exhaust emissions have an influence on platinum and rhodium excretion, but for platinum this influence is rather low compared to the influence of precious metals containing restorations. Copyright © 2016 Elsevier GmbH. All rights reserved.

Strategies for the fabrication of porous platinum electrodes

Energy Technology Data Exchange (ETDEWEB)

Kloke, Arne; Stetten, Felix von; Kerzenmacher, Sven [Laboratory for MEMS Applications, Department of Microsystems Engineering-IMTEK, University of Freiburg, Freiburg (Germany); Zengerle, Roland [Laboratory for MEMS Applications, Department of Microsystems Engineering-IMTEK, University of Freiburg, Freiburg (Germany); BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universitaet Freiburg (Germany)

2011-11-16

Porous platinum is of high technological importance due to its various applications in fuel cells, sensors, stimulation electrodes, mechanical actuators and catalysis in general. Based on a discussion of the general principles behind the reduction of platinum salts and corresponding deposition processes this article discusses techniques available for platinum electrode fabrication. The numerous, different strategies available to fabricate platinum electrodes are reviewed and discussed in the context of their tuning parameters, strengths and weaknesses. These strategies comprise bottom-up approaches as well as top-down approaches. In bottom-up approaches nanoparticles are synthesized in a first step by chemical, photochemical or sonochemical means followed by an electrode formation step by e.g. thin film technology or network formation to create a contiguous and conducting solid electrode structure. In top-down approaches fabrication starts with an already conductive electrode substrate. Corresponding strategies enable the fabrication of substrate-based electrodes by e.g. electrodeposition or the fabrication of self-supporting electrodes by dealloying. As a further top-down strategy, this review describes methods to decorate porous metals other than platinum with a surface layer of platinum. This way, fabrication methods not performable with platinum can be applied to the fabrication of platinum electrodes with the special benefit of low platinum consumption. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Platinum nanoparticles: a non-toxic, effective and thermally stable alternative plasmonic material for cancer therapy and bioengineering.

Science.gov (United States)

Samadi, Akbar; Klingberg, Henrik; Jauffred, Liselotte; Kjær, Andreas; Bendix, Poul Martin; Oddershede, Lene B

2018-05-17

Absorption of near infrared (NIR) light by metallic nanoparticles can cause extreme heating and is of interest for instance in cancer treatment since NIR light has a relatively large penetration depth into biological tissue. Here, we quantify the extraordinary thermoplasmonic properties of platinum nanoparticles and demonstrate their efficiency in photothermal cancer therapy. Although platinum nanoparticles are extensively used for catalysis, they are much overlooked in a biological context. Via direct measurements based on a biological matrix we show that individual irradiated platinum nanoparticles with diameters of 50-70 nm can easily reach surface temperatures up to 900 K. In contrast to gold nanoshells, which are often used for photothermal purposes, we demonstrate that the platinum particles remain stable at these extreme temperatures. The experiments are paralleled by finite element modeling confirming the experimental results and establishing a theoretical understanding of the particles' thermoplasmonic properties. At extreme temperatures it is likely that a vapor layer will form around the plasmonic particle, and we show this scenario to be consistent with direct measurements and simulations. Viability studies demonstrate that platinum nanoparticles themselves are non-toxic at therapeutically relevant concentrations, however, upon laser irradiation we show that they efficiently kill human cancer cells. Therefore, platinum nanoparticles are highly promising candidates for thermoplasmonic applications in the life sciences, in nano-medicine, and for bio-medical engineering.

Functional conjugated pyridines via main-group element tuning.

Science.gov (United States)

Stolar, Monika; Baumgartner, Thomas

2018-03-29

Pyridine-based materials have seen widespread attention for the development of n-type organic materials. In recent years, the incorporation of main-group elements has also explored significant advantages for the development and tunability of organic conjugated materials. The unique chemical and electronic structure of main-group elements has led to several enhancements in conventional organic materials. This Feature article highlights recent main-group based pyridine materials by discussing property enhancements and application in organic electronics.

Zinc and group V element co-implantation in indium phosphide

International Nuclear Information System (INIS)

Yu, Kin Man; Ridgway, M.C.

2000-01-01

Group V elements with mass ranging from 35 to 122 amu have been co-implanted with Zn in InP substrates. Co-implantation with all group V elements drastically reduced Zn out-diffusion and to a certain extent also inhibited Zn in-diffusion. The reduction in out-diffusion was insensitive to the group V element mass and thus, to implantation-induced damage. We believe the group V element excess created an In-vacancy excess that enhanced Zn substitution into the In sublattice. A maximum hole concentration of 7x10 18 cm -3 was achieved with P co-implantation. Electrochemical capacitance-voltage profiling clearly showed a decrease in hole concentration as a function of increasing group V element mass. This was attributed to differences in compensating residual implantation-induced damage

Modification of an ancient subcontinental lithospheric mantle by continental subduction: Insight from the Maowu garnet peridotites in the Dabie UHP belt, eastern China

Science.gov (United States)

Chen, Yi; Su, Bin; Chu, Zhuyin

2017-05-01

Orogenic mantle-derived peridotites commonly originate from the subcontinental lithospheric mantle (SCLM) and thus provide a key target to investigate the modification of the SCLM by a subducting slab. The Maowu ultramafic rocks from the Dabie ultrahigh-pressure (UHP) metamorphic belt have formerly been debated as representing cumulates or mantle-derived peridotites. Detailed petrological and geochemical data presented in this study provide new constraints on the origin and formation of the peridotites involving melt depletion in the ancient SCLM and deep crustal metasomatism. The Maowu garnet dunites have refractory bulk compositions characterized by high Mg# (91.9-92.0) and Ni (2537-2892 ppm) values and low Al2O3 (0.26-0.76 wt.%), CaO (0.05-0.32 wt.%), TiO2 (China craton. Many garnet orthopyroxenite veins crosscutting the Maowu dunites preserve abundant metasomatic textures and show variable enrichment in incompatible elements. Mineral and whole-rock chemistry indicate that these veins represent metasomatic products between the wall dunites and silica-rich hydrous melts under UHP conditions. The veins show large variations in platinum-group element (PGE) signatures and Re-Os isotopes. The garnet-poor orthopyroxenite veins are characterized by low Al2O3 ( 6 wt.%) and S (99-306 ppm) contents and show melt-like PGE patterns and high 187Os/188Os ratios (up to 0.36910). These features, combined with the occurrence of interstitial sulfides in the garnet-rich orthopyroxenite veins, suggest that crust-derived sulfur-saturated silicate melts may have significantly modified the PGE signature and destroyed the Re-Os systematics of the SCLM. However, when the crust-derived silicate melts became sulfur-depleted, such melts would not significantly modify the PGE patterns, radiogenic Os-isotope compositions or the Re-depletion model ages of the SCLM. Consequently, deep crust-mantle interactions in continental subduction zones could induce high degrees of Os isotopic

Study of half-sandwich mono and dinuclear complexes of platinum ...

Indian Academy of Sciences (India)

of platinum group metals containing pyrazolyl pyridine analogues: Synthesis ... sis for specific reactions. Inclusion of ... was poured in to 100 ml of water, resulted in whitish precipitate ..... condition in the presence of potassium carbonate and.

A phenyl-sulfonic acid anchored carbon-supported platinum catalyst for polymer electrolyte fuel cell electrodes

International Nuclear Information System (INIS)

Selvarani, G.; Sahu, A.K.; Choudhury, N.A.; Sridhar, P.; Pitchumani, S.; Shukla, A.K.

2007-01-01

A method, to anchor phenyl-sulfonic acid functional groups with the platinum catalyst supported onto a high surface-area carbon substrate, is reported. The use of the catalyst in the electrodes of a polymer electrolyte fuel cell (PEFC) helps enhancing its performance. Characterization of the catalyst by Fourier transform infra red (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and point-of-zero-charge (PZC) studies suggests that the improvement in performance of the PEFC is facilitated not only by enlarging the three-phase boundary in the catalyst layer but also by providing ionic-conduction paths as well as by imparting negative charge to platinum sites with concomitant oxidation of sulfur present in the carbon support. It is argued that the negatively charged platinum sites help repel water facilitating oxygen to access the catalyst sites. The PEFC with modified carbon-supported platinum catalyst electrodes exhibits 40% enhancement in its power density as compared to the one with unmodified carbon-supported platinum catalyst electrodes

Flow Injection Analysis with Electrochemical Detection for Rapid Identification of Platinum-Based Cytostatics and Platinum Chlorides in Water

Directory of Open Access Journals (Sweden)

Marketa Kominkova

2014-02-01

Full Text Available Platinum-based cytostatics, such as cisplatin, carboplatin or oxaliplatin are widely used agents in the treatment of various types of tumors. Large amounts of these drugs are excreted through the urine of patients into wastewaters in unmetabolised forms. This phenomenon leads to increased amounts of platinum ions in the water environment. The impacts of these pollutants on the water ecosystem are not sufficiently investigated as well as their content in water sources. In order to facilitate the detection of various types of platinum, we have developed a new, rapid, screening flow injection analysis method with electrochemical detection (FIA-ED. Our method, based on monitoring of the changes in electrochemical behavior of analytes, maintained by various pH buffers (Britton-Robinson and phosphate buffer and potential changes (1,000, 1,100 and 1,200 mV offers rapid and cheap selective determination of platinum-based cytostatics and platinum chlorides, which can also be present as contaminants in water environments.

Perubahan Kadar Prostaglandin E2 (PGE2) Setelah Aplikasi Ekstrak Gambir (Uncaria Gambir ROXB) Pada Kasus Pulpitis Ireversible.

OpenAIRE

Samad, Rasmidar

2017-01-01

The dental pulp was soft tissue, reside in the cental of tooth, enclosed by, email, dentine and cementum, Inflammation of dental pulp was called pulpitis. Two groups of pulpitis, among these pulpitis, irreversible pulpitis. Design of this researc pre and post test to evaluate change the levels of prostaglandin E2 (PGE2) post application gambier (Uncaria Gambier Roxb) extract, in January-April 2016 in the Biofarmaca Laboratory Research Center Activities Faclty of Pharmacy.

The effects of thermal-neutron irradiation on platinum and dilute platinum-gold alloys

International Nuclear Information System (INIS)

Piani, C.S.B.

1978-12-01

The effect of varying defect concentrations on the recovery spectrum of thermal-neutron-irradiated pure platinum after isochronal anneals was investigated. The dose-independence of substages I(A), I(B) and I(C), and the dose dependence of substage I(D) and I(E), were observed to be in agreement with electron-irradiated studies. The 120 K substage in pure platinum was shown not to be due to interstitial-interstitial reactions, but could possibly be accounted for in terms of detrapping of interstitials from impurities or intrinsic immobile defects. The 360 K stage was shown to shift and was suppressed with increasing defect concentration. The possible conversion of the crowdion to a dumbbell near 160 K in Stage ll in platinum, as predicted by the two-interstitial model, was investigated by consideration of the initial slopes of the production curves between 80 K and 300 K. A minimum in these slopes was observed near 160 K and could be interpreted as due to the conversion of the highly mobile crowdion to an immobile dumbbell at this temperature. The influence of varying gold concentrations on the recovery spectrum of platinum was investigated in dilute platinum-gold alloys. The characteristics of several additional substages in Stage ll, due to the gold alloying were comparable to the results of electron-irradiation experiments. The observations made with regard to the impurity (gold) dependence of these substages could be interpreted in terms of the concentrations of the interstitials, vacancies and impurities present in the material. The interpretation of these substages was found to be consistent, if the recovery spectrum was investigated as a function of defect concentration [af

A Meta-Analysis of Platinum Plus Gemcitabine or Vinorelbine for Advanced Non-small Cell Lung Cancer

Directory of Open Access Journals (Sweden)

Guanghui GAO

2009-01-01

Full Text Available Background and objective Platinum plus the third-generation agent doublet chemotherapy is the standard regimens and first line chemotherapy for advanced non-small cell lung cancer (NSCLC. The aim of this study is to determine the benefits and harms of platinum plus gemcitabine or vinorelbine for advanced NSCLC. Methods Thedatabases PubMed, CENTRAL, EMBASE and Chinese Biomedical Literature database were retrieved by using the key words "non small cell lung cancer" or "Carcinoma, Non Small Cell Lung" so as to search the studies about the randomized controlled clinical trials (RCT that had compared the gemcitabine plus platinum versus vinorelbine plus platinum for advanced NSCLC. A meta-analysis was conducted. Results Nine randomized controlled trials, with total 2 186 patients,were included. The overall response rate and one-year survival rate of the gemcitabine group were not significantly different from that of vinorelbine regimen (RR=0.91, 95%CI: 0.81-1.03, P =0.15; RR=1.06, 95%CI: 0.96-1.18, P =0.27, respectively. The incidence rate of grade 3-4 netropenia, constipation, phlebitis and grade 1-4 neuropathy were higher in vinorelbine group, just like higher incidence rate of grade 3-4 thrombocytopenia in the gemcitabine group. Conclusion The curative effects of the gemcitabine or vinorelbine plus platinum regimens are similar. The choice of gemcitabine or vinorelbine depends on the toxicity of the drugs and patients' tolerance.

Superconductivity observed in platinum-silicon interface

Energy Technology Data Exchange (ETDEWEB)

Kuo, Pai-Chia, E-mail: paichia@phys.sinica.edu.tw [Research Program on Nanoscience and Nanotechnology, Academia Sinica, Taipei 11529, Taiwan (China); Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China); Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Chen, Chun-Wei [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Lee, Ku-Pin; Shiue, Jessie, E-mail: yshiue@phys.sinica.edu.tw [Research Program on Nanoscience and Nanotechnology, Academia Sinica, Taipei 11529, Taiwan (China); Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China)

2014-05-26

We report the discovery of superconductivity with an onset temperature of ∼0.6 K in a platinum-silicon interface. The interface was formed by using a unique focused ion beam sputtering micro-deposition method in which the energies of most sputtered Pt atoms are ∼2.5 eV. Structural and elemental analysis by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy reveal a ∼ 7 nm interface layer with abundant Pt, which is the layer likely responsible for the superconducting transport behavior. Similar transport behavior was also observed in a gold-silicon interface prepared by the same technique, indicating the possible generality of this phenomenon.

Genetic deletion of the P2Y2 receptor offers significant resistance to development of lithium-induced polyuria accompanied by alterations in PGE2 signaling.

Science.gov (United States)

Zhang, Yue; Pop, Ioana L; Carlson, Noel G; Kishore, Bellamkonda K

2012-01-01

Lithium (Li)-induced polyuria is due to resistance of the medullary collecting duct (mCD) to the action of arginine vasopressin (AVP), apparently mediated by increased production of PGE(2). We previously reported that the P2Y(2) receptor (P2Y(2)-R) antagonizes the action of AVP on the mCD and may play a role in Li-induced polyuria by enhancing the production of PGE(2) in mCD. Hence, we hypothesized that genetic deletion of P2Y(2)-R should ameliorate Li-induced polyuria. Wild-type (WT) or P2Y(2)-R knockout (KO) mice were fed normal or Li-added diets for 14 days and euthanized. Li-induced polyuria, and decreases in urine osmolality and AQP2 protein abundance in the renal medulla, were significantly less compared with WT mice despite the lack of differences in Li intake or terminal serum or inner medullary tissue Li levels. Li-induced increased urinary excretion of PGE(2) was not affected in KO mice. However, prostanoid EP(3) receptor (EP3-R) protein abundance in the renal medulla of KO mice was markedly lower vs. WT mice, irrespective of the dietary regimen. The protein abundances of other EP-Rs were not altered across the groups irrespective of the dietary regimen. Ex vivo stimulation of mCD with PGE(2) generated significantly more cAMP in Li-fed KO mice (130%) vs. Li-fed WT mice (100%). Taken together, these data suggest 1) genetic deletion of P2Y(2)-R offers significant resistance to the development of Li-induced polyuria; and 2) this resistance is apparently due to altered PGE(2) signaling mediated by a marked decrease in EP3-R protein abundance in the medulla, thus attenuating the EP3-mediated decrease in cAMP levels in mCD.

Dissolved Platinum Concentrations in Coastal Seawater: Boso to Sanriku Areas, Japan.

Science.gov (United States)

Mashio, Asami Suzuki; Obata, Hajime; Gamo, Toshitaka

2017-08-01

Platinum, one of the rarest elements in the earth's crust, is now widely used in a range of products, such as catalytic converters in automobiles and anticancer drugs. Increasing use and dispersal of platinum has the potential to affect aquatic environments. Platinum concentrations in open ocean seawater have been found to be very low (approximately 0.2 pmol/L); however, Pt distributions and biogeochemical cycles in coastal areas are unknown. In this study, we investigated Pt concentrations in coastal waters between the Boso and Sanriku areas, Japan, after the 2011 tsunami. We determined sub-picomolar levels of dissolved Pt using isotope-dilution Inductively coupled plasma mass spectrometry after column preconcentration with an anion exchange resin. Dissolved Pt concentrations were found to be in the range 0.20-1.5 pmol/L, with the highest concentration in bottom water of the Boso coastal area, and at stations close to Tokyo Bay. Assuming thermodynamical equilibrium, Pt was determined to be present in the form PtCl 5 (OH) 2- , even in low-oxygen coastal waters. Vertical profiles indicated Pt levels increased toward seafloors near coastal stations and were similar to those of the open ocean at trench stations. High concentrations of dissolved Pt are thought to be derived from coastal sediments.

Regulation of PGE(2) and PGI(2) release from human umbilical vein endothelial cells by actin cytoskeleton

Science.gov (United States)

Sawyer, S. J.; Norvell, S. M.; Ponik, S. M.; Pavalko, F. M.

2001-01-01

Disruption of microfilaments in human umbilical vein endothelial cells (HUVEC) with cytochalasin D (cytD) or latrunculin A (latA) resulted in a 3.3- to 5.7-fold increase in total synthesis of prostaglandin E(2) (PGE(2)) and a 3.4- to 6.5-fold increase in prostacyclin (PGI(2)) compared with control cells. Disruption of the microtubule network with nocodazole or colchicine increased synthesis of PGE(2) 1.7- to 1.9-fold and PGI(2) 1.9- to 2.0-fold compared with control cells. Interestingly, however, increased release of PGE(2) and PGI(2) from HUVEC into the media occurred only when microfilaments were disrupted. CytD treatment resulted in 6.7-fold more PGE(2) and 3.8-fold more PGI(2) released from HUVEC compared with control cells; latA treatment resulted in 17.7-fold more PGE(2) and 11.2-fold more PGI(2) released compared with control cells. Both increased synthesis and release of prostaglandins in response to all drug treatments were completely inhibited by NS-398, a specific inhibitor of cyclooxygenase-2 (COX-2). Disruption of either microfilaments using cytD or latA or of microtubules using nocodazole or colchicine resulted in a significant increase in COX-2 protein levels, suggesting that the increased synthesis of prostaglandins in response to drug treatments may result from increased activity of COX-2. These results, together with studies demonstrating a vasoprotective role for prostaglandins, suggest that the cytoskeleton plays an important role in maintenance of endothelial barrier function by regulating prostaglandin synthesis and release from HUVEC.

Incorporation of transition and platinum group elements (PGE) in Co-rich Mn crusts at Afanasiy-Nikitin Seamount (AFS) in the equatorial S Indian Ocean

Digital Repository Service at National Institute of Oceanography (India)

Glasby, G.P.

in the western Pacific. These mineral grains are typically in the size range 10–20 mm but large grains of sulfides up to 1 mm were found in some cases. These authors also noted that ferromanganese crusts have rough surfaces with low relief (0.1–0.15 mm...-ferrous metals of different composition. Native silver was a major constituent but small amounts of gold, iron, copper, tungsten, Fe-Sb oxides, Zn-Ag-Cu sulfides, rare earth phosphates as well as intermetallic Cu-Zn, Cu-Ni, Sn-Pb-Cu-Ni, Ni-Cr-Mo, Fe-Cr-Ni and Au...

PGE2 mediates EGFR internalization and nuclear translocation via caveolin endocytosis promoting its transcriptional activity and proliferation in human NSCLC cells.

Science.gov (United States)

Bazzani, Lorenzo; Donnini, Sandra; Giachetti, Antonio; Christofori, Gerhard; Ziche, Marina

2018-03-13

Prostaglandin E 2 (PGE 2 ) contributes to tumor progression by promoting cancer cell growth, invasion and by creating a favorable pro-tumor microenvironment. PGE 2 has been reported to transactivate and internalize into the nucleus receptor tyrosine kinases such as Epidermal growth factor receptor (EGFR), thereby supporting tumor progression. Here we demonstrate that in non-small cell lung carcinoma (NSCLC) cells, PGE 2 induces EGFR nuclear translocation via different dynamin-dependent endocytic pathways, promotes the formation of an EGFR-STAT3 complex, affects nuclear EGFR target gene expression and mediates tumor cell proliferation. Indeed, we find that PGE 2 induces EGFR internalization and consequent nuclear import through Clathrin- and Caveolin-mediated endocytosis and through the interaction of EGFR with Importin β1. Within the nucleus, EGFR forms a complex with STAT3, an event blocked by ablation of Clathrin Heavy Chain or Caveolin-1. The combination of EGF and PGE 2 prolongs nuclear EGFR transcriptional activity manifested by the upregulation of CCND1 , PTGS2 , MYC and NOS2 mRNA levels and potentiates nuclear EGFR-induced NSCLC cell proliferation. Additionally, NSCLC patients with high expression of a nuclear EGFR gene signature display shorter survival times than those with low expression, thus showing a putative correlation between nuclear EGFR and poor prognosis in NSCLC. Together, our findings indicate a complex mechanism underlying PGE 2 -induced EGF/EGFR signaling and transcriptional control, which plays a key role in cancer progression.

Human umbilical cord mesenchymal stem cells hUC-MSCs exert immunosuppressive activities through a PGE2-dependent mechanism.

Science.gov (United States)

Chen, Ke; Wang, Ding; Du, Wei Ting; Han, Zhi-Bo; Ren, He; Chi, Ying; Yang, Shao Guang; Zhu, Delin; Bayard, Francis; Han, Zhong Chao

2010-06-01

Human umbilical-cord-derived mesenchymal stem cells (hUC-MSCs) constitute an attractive alternative to bone-marrow-derived MSCs for potential clinical applications because of easy preparation and lower risk of viral contamination. In this study, both proliferation of human peripheral blood mononuclear cells (hPBMCs) and their IFN-gamma production in response to mitogenic or allogeneic stimulus were effectively inhibited by hUC-MSCs. Co-culture experiments in transwell systems indicated that the suppression was largely mediated by soluble factor(s). Blocking experiments identified prostaglandin E(2) (PGE(2)) as the major factor, because inhibition of PGE(2) synthesis almost completely mitigated the immunosuppressive effects, whereas neutralization of TGF-beta, IDO, and NO activities had little effects. Moreover, the inflammatory cytokines, IFN-gamma and IL-1beta, produced by hPBMCs upon activation notably upregulated the expression of cyclooxygenase-2 (COX-2) and the production of PGE(2) by hUC-MSCs. In conclusion, our data have demonstrated for the first time the PGE(2)-mediated mechanism by which hUC-MSCs exert their immunomodulatory effects. Copyright 2010 Elsevier Inc. All rights reserved.

Molecular absorption spectra of beryllium, cerium, lanthanum, iron, and platinum salts

International Nuclear Information System (INIS)

Daidoji, Hidehiro

1980-01-01

The absorption spectra of some salts of beryllium, cerium, lanthanum, iron and platinum in air-acetylene flame were measured in the wavelength range from 200 to 400 nm. A Hitachi 207 type atomic absorption spectrophotometer was used. A deuterium lamp, a home-made continuous radiation lamp and some hollow cathode lamps were used as light sources. The new molecular absorption spectra of cerium, lanthanum and platinum and the absorption spectra due to Be(OH) 2 , LaO, PtH, FeO and FeCl in 200-400 nm region were obtained. Emission spectra of CeO, LaO and FeOH were also obtained. These molecular absorption bands were estimated as absorption errors of maximum 15 times to the sensitivity of each elements in atomic absorption spectrometry. In addition, spectral line interferences of iron were observed in atomic absorption spectrometry of Zn, Cd, Ni, Cu and Cr. (author)

Gut Microbiota Promotes Obesity-Associated Liver Cancer through PGE2-Mediated Suppression of Antitumor Immunity.

Science.gov (United States)

Loo, Tze Mun; Kamachi, Fumitaka; Watanabe, Yoshihiro; Yoshimoto, Shin; Kanda, Hiroaki; Arai, Yuriko; Nakajima-Takagi, Yaeko; Iwama, Atsushi; Koga, Tomoaki; Sugimoto, Yukihiko; Ozawa, Takayuki; Nakamura, Masaru; Kumagai, Miho; Watashi, Koichi; Taketo, Makoto M; Aoki, Tomohiro; Narumiya, Shuh; Oshima, Masanobu; Arita, Makoto; Hara, Eiji; Ohtani, Naoko

2017-05-01

Obesity increases the risk of cancers, including hepatocellular carcinomas (HCC). However, the precise molecular mechanisms through which obesity promotes HCC development are still unclear. Recent studies have shown that gut microbiota may influence liver diseases by transferring its metabolites and components. Here, we show that the hepatic translocation of obesity-induced lipoteichoic acid (LTA), a Gram-positive gut microbial component, promotes HCC development by creating a tumor-promoting microenvironment. LTA enhances the senescence-associated secretory phenotype (SASP) of hepatic stellate cells (HSC) collaboratively with an obesity-induced gut microbial metabolite, deoxycholic acid, to upregulate the expression of SASP factors and COX2 through Toll-like receptor 2. Interestingly, COX2-mediated prostaglandin E 2 (PGE 2 ) production suppresses the antitumor immunity through a PTGER4 receptor, thereby contributing to HCC progression. Moreover, COX2 overexpression and excess PGE 2 production were detected in HSCs in human HCCs with noncirrhotic, nonalcoholic steatohepatitis (NASH), indicating that a similar mechanism could function in humans. Significance: We showed the importance of the gut-liver axis in obesity-associated HCC. The gut microbiota-driven COX2 pathway produced the lipid mediator PGE 2 in senescent HSCs in the tumor microenvironment, which plays a pivotal role in suppressing antitumor immunity, suggesting that PGE 2 and its receptor may be novel therapeutic targets for noncirrhotic NASH-associated HCC. Cancer Discov; 7(5); 522-38. ©2017 AACR. This article is highlighted in the In This Issue feature, p. 443 . ©2017 American Association for Cancer Research.

Prevention of blood transfusion with intravenous iron in gynecologic cancer patients receiving platinum-based chemotherapy.

Science.gov (United States)

Athibovonsuk, Punnada; Manchana, Tarinee; Sirisabya, Nakarin

2013-12-01

To compare the efficacy of intravenous iron and oral iron for prevention of blood transfusions in gynecologic cancer patients receiving platinum-based chemotherapy. Sixty-four non anemic gynecologic cancer patients receiving adjuvant platinum-based chemotherapy were stratified and randomized according to baseline hemoglobin levels and chemotherapy regimen. The study group received 200mg of intravenous iron sucrose immediately after each chemotherapy infusion. The control group received oral ferrous fumarate at a dose of 200mg three times a day. Complete blood count was monitored before each chemotherapy infusion. Blood transfusions were given if hemoglobin level was below 10mg/dl. There were 32 patients in each group. No significant differences in baseline hemoglobin levels and baseline characteristics were demonstrated between both groups. Nine patients (28.1%) in the study group and 18 patients (56.3%) in the control group required blood transfusion through 6 cycles of chemotherapy (p=0.02). Fewer median number of total packed red cell units were required in the study group compared to the control group (0 and 0.5 unit, respectively, p=0.04). Serious adverse events and hypersensitivity reactions were not reported. However, constipation was significantly higher in the control group (3.1% and 40.6%, p=gynecologic cancer patients receiving platinum-based chemotherapy, associated with less constipation than the oral formulation. © 2013 Elsevier Inc. All rights reserved.

Respective roles and interactions of T-lymphocyte and PGE2-mediated monocyte suppressive activities in human newborns and mothers at the time of delivery

International Nuclear Information System (INIS)

Durandy, A.; Fischer, A.; Mamas, S.; Dray, F.; Griscelli, C.

1982-01-01

Recently the concept of a poorly functional humoral immune response in the newborn was proposed. Data have been presented indicating that the impaired newborn B cell maturation, as shown in vitro in a pokeweed mitogen-induced B cell maturation system, is due both to an immaturity of lymphocyte subsets and to an increased suppressive T activity. In the present work, we present evidence that there exists a predominance of a naturally occurring T lymphocyte suppressive activity in the cord blood in that the removal of the suppressive activity by irradiation allows a normal maturation of newborn B cells. Such normal maturation of newborn B cells can also be obtained using mixed cultures of adult T cells and newborn B cells. Newborn suppressor T cells belong to both EA gamma (+) and EA gamma (-) fractions, and it is not known whether these two groups do or do not belong to different subsets. The PGE2-dependent monocyte suppressive activity does not play any role in the suppression observed in newborns since newborn monocytes are poorly suppressive and since they produce a smaller amount of PGE2 than adult monocytes. Some observations suggest, on the contrary, that the suppressive T lymphocytes can regulate the level of the PGE2-dependent monocyte suppressive activity. It should be noticed that similar observations about T lymphocyte and PGE2-dependent monocyte suppressive activities have been made at the same time using mothers' cells. These observations suggest the possibility that such changes in B cell immune regulation may result from an interaction between maternal and fetal lymphoid cells

Characterization of electrochemically modified polycrystalline platinum surfaces

Energy Technology Data Exchange (ETDEWEB)

Krebs, L.C.; Ishida, Takanobu.

1991-12-01

The characterization of electrochemically modified polycrystalline platinum surfaces has been accomplished through the use of four major electrochemical techniques. These were chronoamperometry, chronopotentiommetry, cyclic voltammetry, and linear sweep voltammetry. A systematic study on the under-potential deposition of several transition metals has been performed. The most interesting of these were: Ag, Cu, Cd, and Pb. It was determined, by subjecting the platinum electrode surface to a single potential scan between {minus}0.24 and +1.25 V{sub SCE} while stirring the solution, that the electrocatalytic activity would be regenerated. As a consequence of this study, a much simpler method for producing ultra high purity water from acidic permanganate has been developed. This method results in water that surpasses the water produced by pyrocatalytic distillation. It has also been seen that the wettability of polycrystalline platinum surfaces is greatly dependent on the quantity of oxide present. Oxide-free platinum is hydrophobic and gives a contact angle in the range of 55 to 62 degrees. We have also modified polycrystalline platinum surface with the electrically conducting polymer poly-{rho}-phenylene. This polymer is very stable in dilute sulfuric acid solutions, even under applied oxidative potentials. It is also highly resistant to electrochemical hydrogenation. The wettability of the polymer modified platinum surface is severely dependent on the choice of supporting electrolyte chosen for the electrochemical polymerization. Tetraethylammonium tetrafluoroborate produces a film that is as hydrophobic as Teflon, whereas tetraethylammonium perchlorate produces a film that is more hydrophilic than oxide-free platinum.

Characterization of electrochemically modified polycrystalline platinum surfaces

Energy Technology Data Exchange (ETDEWEB)

Krebs, Leonard C. [State Univ. of New York (SUNY), Stony Brook, NY (United States); Ishida, Takanobu [State Univ. of New York (SUNY), Stony Brook, NY (United States)

1991-12-01

The characterization of electrochemically modified polycrystalline platinum surfaces has been accomplished through the use of four major electrochemical techniques. These were chronoamperometry, chronopotentiommetry, cyclic voltammetry, and linear sweep voltammetry. A systematic study on the under-potential deposition of several transition metals has been performed. The most interesting of these were: Ag, Cu, Cd, and Pb. It was determined, by subjecting the platinum electrode surface to a single potential scan between -0.24 and +1.25 V_SCE while stirring the solution, that the electrocatalytic activity would be regenerated. As a consequence of this study, a much simpler method for producing ultra high purity water from acidic permanganate has been developed. This method results in water that surpasses the water produced by pyrocatalytic distillation. It has also been seen that the wettability of polycrystalline platinum surfaces is greatly dependent on the quantity of oxide present. Oxide-free platinum is hydrophobic and gives a contact angle in the range of 55 to 62 degrees. We have also modified polycrystalline platinum surface with the electrically conducting polymer poly-ρ-phenylene. This polymer is very stable in dilute sulfuric acid solutions, even under applied oxidative potentials. It is also highly resistant to electrochemical hydrogenation. The wettability of the polymer modified platinum surface is severely dependent on the choice of supporting electrolyte chosen for the electrochemical polymerization. Tetraethylammonium tetrafluoroborate produces a film that is as hydrophobic as Teflon, whereas tetraethylammonium perchlorate produces a film that is more hydrophilic than oxide-free platinum.

Solutions of group IV elements in liquid lithium

International Nuclear Information System (INIS)

Dadd, A.T.; Hubberstey, P.; Roberts, P.G.

1982-01-01

The solubilities of tin (0.00 = 22 Sn 5 . A simple thermochemical cycle is used to demonstrate that, whereas carbon dissolves endothermically in both liquid lithium and liquid sodium, the heavier Group IV elements dissolve exothermically. A similar cycle is used to derive solvation enthalpies (for the neutral gaseous species) for all Group IV elements in the two solvents. The trend in solvation enthalpy: C > Si > Ge > Sn > Pb is indicative of a diminishing affinity of solvent for solute and is attributed to the increasing metallic character of the solute as the Group is descended. (author)

A positive feedback loop between progesterone and microsomal prostaglandin E synthase-1-mediated PGE2 promotes production of both in mouse granulosa cells.

Science.gov (United States)

Tamura, Kazuhiro; Naraba, Hiroaki; Hara, Takahiko; Nakamura, Kota; Yoshie, Mikihiro; Kogo, Hiroshi; Tachikawa, Eiichi

2016-03-01

Microsomal prostaglandin E synthase-1 (mPGES-1) is primarily expressed in granulosa cells (GCs) in the preovulatory follicle. Both prostaglandin E2 (PGE2) and progesterone (P4) are implicated in various reproductive functions. Here, we demonstrate that mPges-1 may be a direct downstream target gene of the P4 receptor and P4-stimulated PGE2 secretion can stimulate P4 production in a newly generated mouse GC line (GtsT). Treatment of GtsT cells with a P4 receptor agonist, norgestrel, markedly increased mPGES-1 expression detected by RT-PCR analysis. PGE2 secretion measured by an enzyme-linked immunosorbent assay was enhanced by P4 treatment. Luciferase assays revealed that the proximal promoter region of the mPges-1 gene was responsible for the effects of P4 treatment. Conversely, PGE2 treatment stimulated P4 secretion, which coordinated with mRNA expression of steroidogenic acute regulatory protein. Taken together, P4 may regulate mPGES-1 expression to increase PGE2 secretion and in turn P4 production. An autocrine loop between P4 and PGE2 might function to maintain the increased levels of both in GCs. Copyright © 2016 Elsevier Inc. All rights reserved.

Ultratrace determination of platinum in biological materials via neutron activation and radiochemical separation

International Nuclear Information System (INIS)

Zeisler, R.; Greenberg, R.R.

1982-01-01

A neutron activation analysis scheme based upon a radiochemical separation of the activation products has been developed. The method utilizes the inherent sensitivity of the activation reaction 198 Pt(n,ν) 199 Pt and counting of the daughter nuclide 199 Au. This nuclide is radiochemically separated from interfering activities by homogeneous precipitation as elemental gold. The remaining interference of the secondary reaction 197 Au(n,ν) 198 Au(n,ν) 199 Au from gold in the samples is quantitatively assessed and corrected. During this process accurate gold concentrations in the samples are obtained at ultratrace levels. The analysis scheme is applied to gold and platinum determinations in biological Standard Reference Materials and human liver specimens. Gold and platinum are determined at concentrations of 5x10 - 11 g/g, and at higher levels. (author)

Elements of theory of abelian groups

International Nuclear Information System (INIS)

Lebedenko, V.M.

1977-01-01

Some methods and results of studies on the abelian group theory being an important branch of modern algebra are presented. Some examples of the application of the abelian groups in physics are given. A primary information on commutative groups is presented. The concepts of a group, a subgroup, homomorphism, an order of element are given; those of torsion, torsion-free and mixed groups are considered, as well as the concepts of direct and full direct sums. The concepts of a free group and defining relations, of linear dependence and a rank are given. The main classes of abelian groups and subgroup types are described. Some classical results on the abelian group theory are presented, its modern state is described, the links with other regions of algebra are presented

Corrosion Studies of Platinum Nano-Particles for Fuel Cells

DEFF Research Database (Denmark)

Shim, Signe Sarah

The main focus of the present thesis is on corrosion and prevention of corrosion of platinum particles supported on carbon. This is important for instance in connection with start up and shutdown of fuel cells. The degradation mechanism of platinum particles supported on carbon has been character......The main focus of the present thesis is on corrosion and prevention of corrosion of platinum particles supported on carbon. This is important for instance in connection with start up and shutdown of fuel cells. The degradation mechanism of platinum particles supported on carbon has been...... characterized during oxygen reduction reaction (ORR) condition using identical location (IL) transmission electron microscopy (TEM). A TEM grid was used as the working electrode in an electrochemical setup allowing a direct correlation between the electrochemical response and the TEM analysis. The main results...... thirds and one monolayer of gold on platinum supported on carbon were synthesized by an inverse micelle method. The results obtained appear independent of the gold coverage. It has been shown that the electrochemical active surface areas of the platinum and platinum gold particles synthesized...

Reaction pathways for reduction of nitrate ions on platinum, rhodium, and platinum-rhodium alloy electrodes

International Nuclear Information System (INIS)

Cunha, M.C.P.M. da; De Souza, J.P.I.; Nart, F.C.

2000-01-01

The reduction of nitrate ions on platinum, rhodium, and platinum-rhodium alloy electrodes has been investigated using differential electrochemical mass spectrometry and in situ FTIR measurements. For 3 M HNO 3 concentration it has been found that nitrate starts the reduction with partial N-O bond dissociation and N-N bond formation generating NO and N 2 O. At potentials lower than 0.2 V the reaction proceeds forming dissolved NH 4 + . For potentials lower than 0 V the reduction continues via a multiple pathway reaction leading to the nonselective production of N 2 , NH 2 OH, and N 2 H 2 . On the alloyed electrodes, the production of NO and N 2 O has been observed in both cathodic and anodic scans, while on pure platinum and rhodium electrodes the reaction has been observed only during the cathodic scan. Contrasting with the pure platinum and rhodium alloys, where the N-O bond break starts forming NO and N 2 O, on the alloys HNO 2 has been observed as the first reaction step. For alloys with higher rhodium composition, like Pt 75 Rh 25 , no N 2 has been detected for potentials lower than 0 V

Outpatient desensitization in selected patients with platinum hypersensitivity reactions.

Science.gov (United States)

O'Malley, David M; Vetter, Monica Hagan; Cohn, David E; Khan, Ambar; Hays, John L

2017-06-01

Platinum-based chemotherapies are a standard treatment for both initial and recurrent gynecologic cancers. Given this widespread use, it is important to be aware of the features of platinum hypersensitivity reactions and the subsequent treatment of these reactions. There is also increasing interest in the development of desensitization protocols to allow patients with a history of platinum hypersensitivity to receive further platinum based therapy. In this review, we describe the management of platinum hypersensitivity reactions and the desensitization protocols utilized at our institution. We also describe the clinical categorizations utilized to triage patients to appropriate desensitization protocols. Copyright © 2017 Elsevier Inc. All rights reserved.

Misoprostol, an anti-ulcer agent and PGE2 receptor agonist, protects against cerebral ischemia.

Science.gov (United States)

Li, Jun; Liang, Xibin; Wang, Qian; Breyer, Richard M; McCullough, Louise; Andreasson, Katrin

2008-06-20

Induction of COX-2 activity in cerebral ischemia results in increased neuronal injury and infarct size. Recent studies investigating neurotoxic mechanisms of COX-2 demonstrate both toxic and paradoxically protective effects of downstream prostaglandin receptor signaling pathways. We tested whether misoprostol, a PGE(2) receptor agonist that is utilized clinically as an anti-ulcer agent and signals through the protective PGE(2) EP2, EP3, and EP4 receptors, would reduce brain injury in the murine middle cerebral artery occlusion-reperfusion (MCAO-RP) model. Administration of misoprostol, at the time of MCAO or 2h after MCAO, resulted in significant rescue of infarct volume at 24 and 72h. Immunocytochemistry demonstrated dynamic regulation of the EP2 and EP4 receptors during reperfusion in neurons and endothelial cells of cerebral cortex and striatum, with limited expression of EP3 receptor. EP3-/- mice had no significant changes in infarct volume compared to control littermates. Moreover, administration of misoprostol to EP3+/+ and EP3-/- mice showed similar levels of infarct rescue, indicating that misoprostol protection was not mediated through the EP3 receptor. Taken together, these findings suggest a novel function for misoprostol as a protective agent in cerebral ischemia acting via the PGE(2) EP2 and/or EP4 receptors.

Direct alcohol fuel cells: Increasing platinum performance by modification with sp-group metals

Science.gov (United States)

Figueiredo, Marta C.; Sorsa, Olli; Doan, Nguyet; Pohjalainen, Elina; Hildebrand, Helga; Schmuki, Patrik; Wilson, Benjamin P.; Kallio, Tanja

2015-02-01

By using sp group metals as modifiers, the catalytic properties of Pt can be improved toward alcohols oxidation. In this work we report the performance increase of direct alcohol fuel cells (DAFC) fuelled with ethanol or 2-propanol with platinum based anode electrodes modified with Bi and Sb adatoms. For example, by simply adding Sb to the Pt/C based anode ink during membrane electrode assembly fabrication of a direct ethanol fuel cell (DEFC) its performance is improved three-fold, with more than 100 mV increase in the open circuit potential. For the fuel cell fuelled with 2-propanol high power densities are obtained at very high potentials with these catalyst materials suggesting a great improvement for practical applications. Particularly in the case of Pt/C-Bi, the improvement is such that within 0.6 V (from 0.7 to 0.1 V) the power densities are between 7 and 9 mW/cm2. The results obtained with these catalysts are in the same range as those obtained with other bimetallic catalysts comprising of PtRu and PtSn, which are currently considered to be the best for these type of fuel cells and that are obtained by more complicated (and consequently more expensive) methods.

Recovery of Platinum Group Metals from Spent Catalysts Using Iron Chloride Vapor Treatment

Science.gov (United States)

Taninouchi, Yu-ki; Okabe, Toru H.

2018-05-01

The recovery of platinum group metals (PGMs) from spent automobile catalysts is a difficult process because of their relatively low contents in the scrap. In this study, to improve the efficiency of the existing recycling techniques, a novel physical concentration method involving treatment with FeCl2 vapor has been examined. The reactions occurring between typical catalyst components and FeCl2 vapor are discussed from the thermodynamic point of view, and the validity of the proposed technique was experimentally verified. The obtained results indicate that the vapor treatment at around 1200 K (927 °C) can effectively alloy PGMs (Pt, Pd, and Rh) with Fe, resulting in the formation of a ferromagnetic alloy. It was also confirmed that cordierite and alumina (the major catalyst components) remained unreacted after the vapor treatment, while ceria species were converted into oxychlorides. The samples simulating the automobile catalyst were also subjected to magnetic separation after the treatment with FeCl2 vapor; as a result, PGMs were successfully extracted and concentrated in the form of a magnetic powder. Thus, the FeCl2 vapor treatment followed by magnetic separation can be utilized for recovering PGMs directly from spent catalysts as an effective pretreatment for the currently used recycling methods.

Influence of platinum group metal-free catalyst synthesis on microbial fuel cell performance

Science.gov (United States)

Santoro, Carlo; Rojas-Carbonell, Santiago; Awais, Roxanne; Gokhale, Rohan; Kodali, Mounika; Serov, Alexey; Artyushkova, Kateryna; Atanassov, Plamen

2018-01-01

Platinum group metal-free (PGM-free) ORR catalysts from the Fe-N-C family were synthesized using sacrificial support method (SSM) technique. Six experimental steps were used during the synthesis: 1) mixing the precursor, the metal salt, and the silica template; 2) first pyrolysis in hydrogen rich atmosphere; 3) ball milling; 4) etching the silica template using harsh acids environment; 5) the second pyrolysis in ammonia rich atmosphere; 6) final ball milling. Three independent batches were fabricated following the same procedure. The effect of each synthetic parameters on the surface chemistry and the electrocatalytic performance in neutral media was studied. Rotating ring disk electrode (RRDE) experiment showed an increase in half wave potential and limiting current after the pyrolysis steps. The additional improvement was observed after etching and performing the second pyrolysis. A similar trend was seen in microbial fuel cells (MFCs), in which the power output increased from 167 ± 2 μW cm-2 to 214 ± 5 μW cm-2. X-ray Photoelectron Spectroscopy (XPS) was used to evaluate surface chemistry of catalysts obtained after each synthetic step. The changes in chemical composition were directly correlated with the improvements in performance. We report outstanding reproducibility in both composition and performance among the three different batches.

Electrochemical behavior of platinum nanoparticles on a carbon xerogel support modified with a [(trifluoromethyl)-benzenesulfonyl]imide electrolyte.

Science.gov (United States)

Liu, Bing; Mei, Hua; DesMarteau, Darryl; Creager, Stephen E

2014-12-11

A monoprotic [(trifluoromethyl)benzenesulfonyl]imide (SI) superacid electrolyte was used to covalently modify a mesoporous carbon xerogel (CX) support via reaction of the corresponding trifluoromethyl aryl sulfonimide diazonium zwitterion with the carbon surface. Electrolyte attachment was demonstrated by elemental analysis, acid-base titration, and thermogravimetric analysis. The ion-exchange capacity of the fluoroalkyl-aryl-sulfonimide-grafted carbon xerogel (SI-CX) was ∼0.18 mequiv g(-1), as indicated by acid-base titration. Platinum nanoparticles were deposited onto the SI-grafted carbon xerogel samples by the impregnation and reduction method, and these materials were employed to fabricate polyelectrolyte membrane fuel-cell (PEMFC) electrodes by the decal transfer method. The SI-grafted carbon-xerogel-supported platinum (Pt/SI-CX) was characterized by X-ray diffraction and transmission electron microscopy to determine platinum nanoparticle size and distribution, and the findings are compared with CX-supported platinum catalyst without the grafted SI electrolyte (Pt/CX). Platinum nanoparticle sizes are consistently larger on Pt/SI-CX than on Pt/CX. The electrochemically active surface area (ESA) of platinum catalyst on the Pt/SI-CX and Pt/CX samples was measured with ex situ cyclic voltammetry (CV) using both hydrogen adsorption/desorption and carbon monoxide stripping methods and by in situ CV within membrane electrode assemblies (MEAs). The ESA values for Pt/SI-CX are consistently lower than those for Pt/CX. Some possible reasons for the behavior of samples with and without grafted SI layers and implications for the possible use of SI-grafted carbon layers in PEMFC devices are discussed.

TGF-β1 downregulates COX-2 expression leading to decrease of PGE2 production in human lung cancer A549 cells, which is involved in fibrotic response to TGF-β1.

Directory of Open Access Journals (Sweden)

Erina Takai

Full Text Available Transforming growth factor-ß1 (TGF-β1 is a multifunctional cytokine that is involved in various pathophysiological processes, including cancer progression and fibrotic disorders. Here, we show that treatment with TGF-β1 (5 ng/mL induced downregulation of cyclooxygenase-2 (COX-2, leading to reduced synthesis of prostaglandin E2 (PGE2, in human lung cancer A549 cells. Treatment of cells with specific inhibitors of COX-2 or PGE2 receptor resulted in growth inhibition, indicating that the COX-2/PGE2 pathway contributes to proliferation in an autocrine manner. TGF-β1 treatment induced growth inhibition, which was attenuated by exogenous PGE2. TGF-β1 is also a potent inducer of epithelial mesenchymal transition (EMT, a phenotype change in which epithelial cells differentiate into fibroblastoid cells. Supplementation with PGE2 or PGE2 receptor EP4 agonist PGE1-alcohol, as compared with EP1/3 agonist sulprostone, inhibited TGF-β1-induced expression of fibronectin and collagen I (extracellular matrix components. Exogenous PGE2 or PGE2 receptor agonists also suppressed actin remodeling induced by TGF-β1. These results suggest that PGE2 has an anti-fibrotic effect. We conclude that TGF-β1-induced downregulation of COX-2/PGE2 signaling is involved in facilitation of fibrotic EMT response in A549 cells.

The probability that a pair of group elements is autoconjugate

Indian Academy of Sciences (India)

[1] Alghamdi A M and Russo F G, A generalization of the probability that the commutator of two group elements is equal to a given element, Bull. Iranian Math. Soc. 38 (2012). 973–986. [2] Blackburn S R, Britnell J R and Wildon M, The probability that a pair of elements of a finite group are conjugate, J. London Math. Soc.

Platinum Group Thiophenoxyimine Complexes: Syntheses,Crystallographic and Computational Studies of Structural Properties

Energy Technology Data Exchange (ETDEWEB)

Krinsky, Jamin L.; Arnold, John; Bergman, Robert G.

2006-10-03

Monomeric thiosalicylaldiminate complexes of rhodium(I) and iridium(I) were prepared by ligand transfer from the homoleptic zinc(II) species. In the presence of strongly donating ligands, the iridium complexes undergo insertion of the metal into the imine carbon-hydrogen bond. Thiophenoxyketimines were prepared by non-templated reaction of o-mercaptoacetophenone with anilines, and were complexed with rhodium(I), iridium(I), nickel(II) and platinum(II). X-ray crystallographic studies showed that while the thiosalicylaldiminate complexes display planar ligand conformations, those of the thiophenoxyketiminates are strongly distorted. Results of a computational study were consistent with a steric-strain interpretation of the difference in preferred ligand geometries.

Evidence of substance P autocrine circuitry that involves TNF-α, IL-6, and PGE2 in endogenous pyrogen-induced fever.

Science.gov (United States)

Brito, Haissa Oliveira; Barbosa, Felipe L; Reis, Renata Cristiane Dos; Fraga, Daniel; Borges, Beatriz S; Franco, Celia R C; Zampronio, Aleksander Roberto

2016-04-15

Substance P (SP) is involved in fever that is induced by lipopolysaccharide (LPS) but not by interleukin-1β or macrophage inflammatory protein-1α. Intracerebroventricular (i.c.v.) administration of the neurokinin-1 (NK1) receptor antagonist SR140333B in rats reduced fever that was induced by an i.c.v. injection of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), prostaglandin E2 (PGE2), corticotropin-releasing factor (CRF), endothelin-1 (ET-1), and morphine (MOR). Furthermore, an i.c.v. injection of SP induced a febrile response that was inhibited by indomethacin concomitant with an increase in PGE2 levels in cerebrospinal fluid. Lipopolysaccharide and PGE2 caused higher expression and internalization of NK1 receptors in the hypothalamus which were prevented by SR140333B. These data suggest that SP is an important mediator of fever, in which it induces a prostaglandin-dependent response and is released after TNF-α, IL-6, PGE2, CRF, endogenous opioids, and ET-1. Copyright © 2016 Elsevier B.V. All rights reserved.

Prostaglandin E 2 (PgE 2 ) Inhibition By Crude Extracts Of Selected ...

African Journals Online (AJOL)

This study was undertaken to assess anti-inflammatory activity of crude extracts of Cassine transvaalensis Burtt-Davy, Clerodendrum uncinatum Schinz and Commiphora glandulosa Schinz using COX inhibition assay. Water extract of C. transvaalensis root bark (125mg/ml) exhibited a (90%) PGE2 inhibition in ...

Iodometric determination of platinum(4) using amperometry

International Nuclear Information System (INIS)

Zakharov, V.A.; Gavva, N.F.; Songina, O.A.

1976-01-01

The possibility of iodometric determination of platinum (4) by amperometric titration has been investigated. Titration has been conducted at zero potential of platinum reference electrode. Voltampere curves and absorption spectra of the solutions have been recorded to elucidate the nature of platinum (4) interaction with iodide-ion. It has been established that in the case of small excess of iodide complex [PtI 6 ] 2- is formed. When there is a considerable excess of KI, platinum (4) is reduced to Pt(2) with the formation of [PtI 4 ] 2 - and liberation of free iodine. Optimal for iodometric titration of Pt(4) is the use of acetate ot phosphate background solution with pH 6-8 with respect to 1M KI which is attained by adding 3 g of solid KI to 20 ml of the solution being titrated. Under these conditions the limit of platinum detection is 0.5 mkg/ml. Determination of Pt (4) is not hindered by the presence of 200-fold amounts of Cr(6), V(5), and Ni(2) as well as by 20-10-fold amounts of As(5), Sb(5), Se(4), Te(4), Rh(3), and Ir(3), Determination is hindered by the presence of Pd(2), Fe(3), Ir(4), and Cu(2) which, however, can easily be overcome. The possibility has been shown of using the developed technique for analysis of platinum catalysts and alloys

Rhenium–platinum antitumor systems

Directory of Open Access Journals (Sweden)

A. V. Shtemenko

2017-04-01

Full Text Available This review provides an overlook of design (in short, antitumor and other biological activity of quadruple-bonded cluster dirhenium(III compounds and their synergism with cisplatin. In particular, we describe the work of the rhenium-platinum antitumor system (introduction of rhenium and platinum compounds. Among known metal-based anticancer drugs and drug candidates dirhenium(III compounds differ profoundly due to their strong antiradical and antioxidant properties determined by quadruple bond unsaturation. Such advantages of metal complexes as more expressed redox chemical propertie should be exploited for creating more efficient anticancer drugs. Combination of drugs leads to synergistic effects and/or to lowe­ring toxicity of platinides and is very promising in cancer chemotherapy. The review covers the follo­wing items: design of quadruple bonded dirhenium(III clusters, their spectral and antiradical properties (in short; interaction of the dirhenium(III compounds with lipids and formation of liposomes; interaction of the dirhenium(III compounds with erythrocytes and their antihemolytic activity in the models of hemolytic anemia; anticancer activity of dirhenium clusters and work of the rhenium-platinum antitumor system; antianemic and antioxidant properties of the dirhenium(III compounds in the model of tumor growth; interaction of the dirhenium(III compounds with nucleobases and DNA. Some modern trends in the field of bioinorganic and medicinal chemi­stry are also considered regarding their connection to the rhenium-platinum system efficiency: use of combinational therapy and nanomaterials; involvement of some biologically active ligands and redox-activation strategy, etc.

A NEW EMPIRICAL INVESTIGATION OF THE PLATINUM SPOT RETURNS

Directory of Open Access Journals (Sweden)

Simone Kruse

2017-08-01

Full Text Available The global platinum market has been in downturn and unstable for five consecutive years, and thus market participants are demanding effective quantitative risk management tools. Since platinum is so widely used and serves as an important investment vehicle, the importance of risk management of platinum spot returns cannot be understated. In this paper, we take advantage of a very popular econometric model, the generalized autoregressive conditional heteroscedasticity (GARCH model, for platinum returns. We received two important findings by using the conventional GARCH models in explain daily platinum spot returns. First, it is crucial to introduce heavy-tailed distribution to explain conditional heavy tails; and second, the NRIG distribution performs better than the most widely-used heavy-tailed distribution, the Student’s t distribution.

Mechanism of Platinum Derivatives Induced Kidney Injury

Directory of Open Access Journals (Sweden)

Feifei YAN

2015-09-01

Full Text Available Platinum derivatives are the most widely used chemotherapeutic agents to treat solid tumors including ovarian, head and neck, and testicular germ cell tumors, lung cancer, and colorectal cancer. Two major problems exist, however, in the clinic use of platinum derivatives. One is the development of tumor resistance to the drug during therapy, leading to treatment failure. The other is the drug’s toxicity such as the cisplatin’s nephrotoxicity, which limits the dose that can be administered. This paper describes the mechanism of platinum derivatives induced kidney injury.

Employee perceptions of symbolic corporate identity elements and employer-employee relationships at Lonmin Platinum / L. Holtzhausen

OpenAIRE

Holtzhausen, Lida

2007-01-01

Large multi-national corporations experience more and more pressure to maintain good relationships with their stakeholders, including employees. Concurrent with this, the focus of Corporate Communication management has shifted from pure communication management to relationship management. Lonmin Platinum, a mining company within the South African mining and minerals sector is no exception in this regard. In fact, due to the apartheid legacy and government regulations that ar...

Prostaglandin E (dmPGE{sub 2}) action in vitro on the activity of rat liver Golgi apparatus galactosyltransferase

Energy Technology Data Exchange (ETDEWEB)

Kordowiak, A.M.; Tomecki, J.; Procyk, K.; Kapusta, P. [Uniwersytet Jagiellonski, Cracow (Poland)

1993-12-31

In vitro addition of 16,16`-dimethyl prostaglandin E{sub 2} to Golgi-rich membrane fraction in final concentration of 0.1 {mu}g/1 mg of protein increased generally the activity of galactosyltransferase in comparison with control. The percentage of phospholipids in the whole fraction was similar in both investigated groups, only the sum of phosphatidylenoamine + phosphatidic acid was significantly lower after addition of dmPGE{sub 2} than in the control (0.001 < P < 0.01). (author). 25 refs, 2 figs, 1 tab.

Highly siderophile element geochemistry of peridotites and pyroxenites from Horní Bory, Bohemian Massif: Implications for HSE behaviour in subduction-related upper mantle

Czech Academy of Sciences Publication Activity Database

Ackerman, Lukáš; Pitcher, L.; Strnad, L.; Puchtel, I. S.; Jelínek, E.; Walker, R. J.; Rohovec, Jan

2013-01-01

Roč. 100, č. 1 (2013), s. 158-175 ISSN 0016-7037 R&D Projects: GA AV ČR KJB300130902 Institutional research plan: CEZ:AV0Z30130516 Institutional support: RVO:67985831 Keywords : alloy * high pressure * high temperature * igneous geochemistry * isotopic composition * mass balance * nappe * osmium isotope * peridotite * petrography * platinum group element * precipitation (chemistry) * pyroxenite * siderophile element * subduction * sulfide * upper mantle Subject RIV: DD - Geochemistry Impact factor: 4.250, year: 2013

Collective Behavior of Water on Platinum

Science.gov (United States)

Limmer, David; Willard, Adam; Chandler, David

2012-02-01

We present the results of molecular dynamics simulations of a interface between water and a platinum electrode. Using importance sampling techniques we probe a variety of collective phenomenon that emerge at the interface. We consider platinum electrodes with two different geometries and discuss how different behaviors result from a competition between geometrical frustration and favorable local interactions.

Novel 3-(aminomethyl)naphthoquinone mannich base-platinum(IV) complexes: synthesis, characterization, electrochemical and cytotoxic studies

International Nuclear Information System (INIS)

Silva, Gustavo B. da; Neves, Amanda P.; Vargas, Maria D.; Alves, Wagner A.; Marinho-Filho, Jose D.B.; Pessoa, Claudia; Moraes, Manoel O.; Costa-Lotufo, Leticia V.

2013-01-01

Three novel platinum(IV) complexes cis,cis,trans-[Pt(HL1-3)Cl 2 (OH) 2 ] 1b-3b(HL = 2-hydroxy-3-[(R 1 -amino)(pyridin-2-yl)methyl]-1,4-naphthoquinone, R 1 = n-butyl, HL1; n-heptyl, HL2 and n-decyl, HL3) have been obtained from the oxidation of the respective precursors cis-[Pt(HL1-3)Cl 2 ] 1a-3a. Cyclic voltammetry studies of 1b-3b in MeCN showed the quasi reversible naphthoquinonate (NQO - , i.e., L - ) redox process and irreversible process attributed to the reduction of the Pt 4+ /Pt 2+ pair, at potentials about 400 mV less negative than for the cisplatin precursor cis,cis,trans-[Pt(NH 3 ) 2 Cl 2 (OH) 2 ]. Hydrogen bond interaction between the naphthoquinone 2-hydroxyl group and an axially coordinated hydroxide ligand in 1b-3b has been proposed to favor the Pt 4+ /Pt 2+ reduction. The cytotoxicity studies against four human cancer cell lines have shown that in general the platinum(IV) and platinum(II)derivatives exhibit the same cytotoxic profile and are all more active than cisplatin. The lowest in vitro IC 50 values have been observed for 2b-3b, which bear ligands with the largest R 1 groups (HL2-HL3) being the most lipophilic. Furthermore similar IC 50 values for platinum(II) and platinum(IV) complexes of the same ligands have been associated with rapid in vitro reduction of the latter complexes to afford 1a-3a. (author)

Study of gold-platinum and platinum-gold surface modification and its influence on hydrogen evolution and oxygen reduction

Directory of Open Access Journals (Sweden)

BRANIMIR N. GRGUR

2005-02-01

Full Text Available Surface modification of the electrodes was conducted from sulfuric acid solutions containing the corresponding metal–chloride complexes using cyclic voltammetry. Comparing the charges of the hydrogen underpotential deposition region, and the corresponding oxide reduction regions, it is concluded that a platinum overlayer on gold forms 3D islands, while gold on platinum forms 2D islands. Foreign metals present in an amount of up to one monolayer exert an influence on the change in reaction rate with respect to both hydrogen evolution (HER and oxygen reduction (ORR reactions. Aplatinum overlayer on a gold substrate increases the activity forHER and for ORR, compared with pure gold. These results can be understood in terms of a simple model, in which the change in the H and OH binding energies are directly proportional to the shift of the d-bond center of the overlayer. On the contrary, a gold layer on platinum slightly decreases the activity for both reactions compared with pure platinum.

Overexpression of BLM promotes DNA damage and increased sensitivity to platinum salts in triple negative breast and serous ovarian cancers

DEFF Research Database (Denmark)

Birkbak, N. J.; Li, Y.; Pathania, S

2018-01-01

inhibitor treatment. We identified two genes, the Bloom helicase (BLM) and Fanconi anemia complementation group I (FANCI), that have both increased DNA copy number and gene expression in the platinum sensitive cases. Increased level of expression of these two genes was also associated with platinum...

PGE2 maintains the tone of the guinea pig trachea through a balance between activation of contractile EP1 receptors and relaxant EP2 receptors

Science.gov (United States)

Säfholm, J; Dahlén, S-E; Delin, I; Maxey, K; Stark, K; Cardell, L-O; Adner, M

2013-01-01

Background and Purpose The guinea pig trachea (GPT) is commonly used in airway pharmacology. The aim of this study was to define the expression and function of EP receptors for PGE2 in GPT as there has been ambiguity concerning their role. Experimental Approach Expression of mRNA for EP receptors and key enzymes in the PGE2 pathway were assessed by real-time PCR using species-specific primers. Functional studies of GPT were performed in tissue organ baths. Key Results Expression of mRNA for the four EP receptors was found in airway smooth muscle. PGE2 displayed a bell-shaped concentration–response curve, where the initial contraction was inhibited by the EP1 receptor antagonist ONO-8130 and the subsequent relaxation by the EP2 receptor antagonist PF-04418948. Neither EP3 (ONO-AE5-599) nor EP4 (ONO-AE3-208) selective receptor antagonists affected the response to PGE2. Expression of COX-2 was greater than COX-1 in GPT, and the spontaneous tone was most effectively abolished by selective COX-2 inhibitors. Furthermore, ONO-8130 and a specific PGE2 antibody eliminated the spontaneous tone, whereas the EP2 antagonist PF-04418948 increased it. Antagonists of other prostanoid receptors had no effect on basal tension. The relaxant EP2 response to PGE2 was maintained after long-term culture, whereas the contractile EP1 response showed homologous desensitization to PGE2, which was prevented by COX-inhibitors. Conclusions and Implications Endogenous PGE2, synthesized predominantly by COX-2, maintains the spontaneous tone of GPT by a balance between contractile EP1 receptors and relaxant EP2 receptors. The model may be used to study interactions between EP receptors. PMID:22934927

Effects of para-substituents of styrene derivatives on their chemical reactivity on platinum nanoparticle surfaces

Science.gov (United States)

Hu, Peiguang; Chen, Limei; Deming, Christopher P.; Lu, Jia-En; Bonny, Lewis W.; Chen, Shaowei

2016-06-01

Stable platinum nanoparticles were successfully prepared by the self-assembly of para-substituted styrene derivatives onto the platinum surfaces as a result of platinum-catalyzed dehydrogenation and transformation of the vinyl groups to the acetylene ones, forming platinum-vinylidene/-acetylide interfacial bonds. Transmission electron microscopic measurements showed that the nanoparticles were well dispersed without apparent aggregation, suggesting sufficient protection of the nanoparticles by the organic capping ligands, and the average core diameter was estimated to be 2.0 +/- 0.3 nm, 1.3 +/- 0.2 nm, and 1.1 +/- 0.2 nm for the nanoparticles capped with 4-tert-butylstyrene, 4-methoxystyrene, and 4-(trifluoromethyl)styrene, respectively, as a result of the decreasing rate of dehydrogenation with the increasing Taft (polar) constant of the para-substituents. Importantly, the resulting nanoparticles exhibited unique photoluminescence, where an increase of the Hammett constant of the para-substituents corresponded to a blue-shift of the photoluminescence emission, suggesting an enlargement of the HOMO-LUMO band gap of the nanoparticle-bound acetylene moieties. Furthermore, the resulting nanoparticles exhibited apparent electrocatalytic activity towards oxygen reduction in acidic media, with the best performance among the series of samples observed with the 4-tert-butylstyrene-capped nanoparticles due to an optimal combination of the nanoparticle core size and ligand effects on the bonding interactions between platinum and oxygen species.Stable platinum nanoparticles were successfully prepared by the self-assembly of para-substituted styrene derivatives onto the platinum surfaces as a result of platinum-catalyzed dehydrogenation and transformation of the vinyl groups to the acetylene ones, forming platinum-vinylidene/-acetylide interfacial bonds. Transmission electron microscopic measurements showed that the nanoparticles were well dispersed without apparent

Platinum stable isotope ratio measurements by double-spike multiple collector ICPMS

DEFF Research Database (Denmark)

Creech, John; Baker, Joel; Handler, Monica

2013-01-01

We present a new technique for the precise determination of platinum (Pt) stable isotope ratios by multiple-collector inductively coupled plasma mass spectrometry (MC-ICPMS) using two different Pt double-spikes ( Pt-Pt and Pt-Pt). Results are expressed relative to the IRMM-010 Pt isotope standard......) can be obtained on Pt stable isotope ratios with either double-spike. Elemental doping tests reveal that double-spike corrected Pt stable isotope ratios are insensitive to the presence of relatively high (up to 10%) levels of matrix elements, although the Pt-Pt double-spike is affected by an isobaric...... = 7.308%) results in a redefined Pt atomic weight of 195.08395 ± 0.00068. Using our technique we have measured small, reproducible and statistically significant offsets in Pt stable isotope ratios between different Pt element standards and the IRMM-010 standard, which potentially indicates...

Regulation of PGE2 signaling pathways and TNF-alpha signaling pathways on the function of bone marrow-derived dendritic cells and the effects of CP-25.

Science.gov (United States)

Li, Ying; Sheng, Kangliang; Chen, Jingyu; Wu, Yujing; Zhang, Feng; Chang, Yan; Wu, Huaxun; Fu, Jingjing; Zhang, Lingling; Wei, Wei

2015-12-15

This study was to investigate PGE2 and TNF-alpha signaling pathway involving in the maturation and activation of bone marrow dendritic cells (DCs) and the effect of CP-25. Bone marrow DCs were isolated and stimulated by PGE2 and TNF-alpha respectively. The markers of maturation and activation expressed on DCs, such as CD40, CD80, CD83, CD86, MHC-II, and the ability of antigen uptake of DCs were analyzed by flow cytometry. The proliferation of T cells co-cultured with DCs, the signaling pathways of PGE2-EP4-cAMP and TNF-alpha-TRADD-TRAF2-NF-κB in DCs were analyzed. The results showed that both PGE2 and TNF-alpha up-regulated the expressions of CD40, CD80, CD83, CD86, and MHC-II, decreased the antigen uptake of DCs, and DCs stimulated by PGE2 or TNF-alpha could increase T cell proliferation. CP-25 (10(-5), 10(-6), and 10(-7)mol/l) decreased significantly the expressions of CD40, CD80, CD83, CD86 and MHC-II, increased the antigen uptake of DCs, and suppressed T cell proliferation induced by DCs. PGE2 increased the expressions of EP4, NF-κB and down-regulated cAMP level of DCs. TNF-alpha could also up-regulate TNFR1, TRADD, TRAF2, and NF-κB expression of DCs. CP-25 (10(-5), 10(-6), and 10(-7)mol/l) decreased the expressions of EP4 and NF-κB, increased cAMP level in DCs stimulated by PGE2. CP-25 (10(-5), 10(-6), and 10(-7)mol/l) also could down-regulate significantly TNFR1, TRADD, TRAF2, and NF-κB expression in DCs stimulated by TNF-alpha. These results demonstrate that PGE2 and TNF-alpha could enhance DCs functions by mediating PGE2-EP4-cAMP pathway, TNF-alpha-TNFR1-TRADD-TRAF2-NF-κB pathway respectively. CP-25 might inhibit the function of DCs through regulating PGE2-EP4-cAMP and TNF-alpha-TNFR1-TRADD-TRAF2-NF-κB pathways. Copyright © 2015 Elsevier B.V. All rights reserved.

Single electron detachment of carbon group and oxygen group elements incident on helium

International Nuclear Information System (INIS)

Huang Yongyi; Li Guangwu; Gao Yinghui; Yang Enbo; Gao Mei; Lu Fuquan; Zhang Xuemei

2006-01-01

The absolute single electron detachment (SED) cross sections of carbon group elements C - , Si - , Ge - in the energy range of 0.05-0.29 a.u. (5 keV-30 keV) and oxygen group elements O - and S - 0.08-0.27 a.u. (5 keV-30 keV), incident on helium are measured with growth rate method. In our energy region, the SED cross sections of C - , Si - , S - and Ge - increase with the projectiles velocity, at the same time, O - cross sections reach a conspicuous maximum at 0.18 a.u. Some abnormal behavior occurs in measurement of SED cross sections for the oxygen group collision with helium. Our results have been compared with a previous work

Platinum, palladium, and rhodium in volcanic and plutonic rocks from the Gravina-Nutzotin belt, Alaska

Science.gov (United States)

Page, Norman J; Berg, Henry C.; Haffty, Joseph

1977-01-01

The Gravina-Nutzotin belt of Middle (?) Jurassic to middle Cretaceous sedimentary and volcanic rocks in south and southeastern Alaska includes concentrically zoned ultramafic complexes known to contain platinum-group metals. Previous isotopic, petrologic, and geologic studies suggested a close relation in time and space between the volcanic rocks and the ultramafic complexes. Interpretation of 40 analyses for platinum, palladium, and rhodium in volcanic and plutonic rocks of the belt indicates a strong geochemical correlation between the two groups of rocks and is in support of their being cogenetic either from directly connected magma chambers and flows or indirectly by selective concentration processes from similar mantle material.

Nano carbon supported platinum catalyst interaction behavior with perfluorosulfonic acid ionomer and their interface structures

DEFF Research Database (Denmark)

Andersen, Shuang Ma

2016-01-01

behavior of Nafion ionomer on platinized carbon nano fibers (CNFs), carbon nano tubes (CNTs) and amorphous carbon (Vulcan). The interaction is affected by the catalyst surface oxygen groups as well as porosity. Comparisons between the carbon supports and platinized equivalents are carried out. It reveals......The interaction between perfluorosulfonic acid ionomer and supported platinum catalyst is essential. It directly influences platinum accessibility, stability of carbon support and platinum, proton conductivity and electron conductivity in an electrode. In this study, we compare the adsorption...... that the platinization step modifies the surface nature of the carbon supports in terms of specific surface area, crystallinity and especially porosity; therefore, ionomer adsorption over carbon is not always representative for the ionomer adsorption over carbon supported catalyst, though indicative. Moreover...

Recovery of Platinum from Dilute Chloride Media Using Biosorbents

Science.gov (United States)

Zeytuncu, B.; Morcali, M. H.; Yucel, O.

Pistachio nut shells and Rice husk, a biomass residue, were investigated as adsorbents for the platinum uptake from synthetically prepared dilute chloroplatinic acid solutions. The effects of the different uptake parameters on platinum uptake (%) were studied in detail on a batch sorption. Before the pistachio nut shell material was activated, platinum uptake (%) was poor compared with rice husk. However, after the pistachio nut shell material was activated at 1000°C under an argon atmosphere, the platinum uptake (%) increased two-fold. The pistachio nut shell (inactivated and activated) and rice husk were characterized by Attenuated Total Reflection-Fourier transform infrared spectroscopy (ATR-FTIR).

Bio-inspired routes for synthesizing efficient nanoscale platinum electrocatalysts

Energy Technology Data Exchange (ETDEWEB)

Cha, Jennifer N. [Univ. of California, San Diego, CA (United States); Wang, Joseph [Univ. of California, San Diego, CA (United States)

2014-08-31

The overall objective of the proposed research is to use fundamental advances in bionanotechnology to design powerful platinum nanocrystal electrocatalysts for fuel cell applications. The new economically-viable, environmentally-friendly, bottom-up biochemical synthetic strategy will produce platinum nanocrystals with tailored size, shape and crystal orientation, hence leading to a maximum electrochemical reactivity. There are five specific aims to the proposed bio-inspired strategy for synthesizing efficient electrocatalytic platinum nanocrystals: (1) isolate peptides that both selectively bind particular crystal faces of platinum and promote the nucleation and growth of particular nanocrystal morphologies, (2) pattern nanoscale 2-dimensional arrays of platinum nucleating peptides from DNA scaffolds, (3) investigate the combined use of substrate patterned peptides and soluble peptides on nanocrystal morphology and growth (4) synthesize platinum crystals on planar and large-area carbon electrode supports, and (5) perform detailed characterization of the electrocatalytic behavior as a function of catalyst size, shape and morphology. Project Description and Impact: This bio-inspired collaborative research effort will address key challenges in designing powerful electrocatalysts for fuel cell applications by employing nucleic acid scaffolds in combination with peptides to perform specific, environmentally-friendly, simultaneous bottom-up biochemical synthesis and patterned assembly of highly uniform and efficient platinum nanocrystal catalysts. Bulk synthesis of nanoparticles usually produces a range of sizes, accessible catalytic sites, crystal morphologies, and orientations, all of which lead to inconsistent catalytic activities. In contrast, biological systems routinely demonstrate exquisite control over inorganic syntheses at neutral pH and ambient temperature and pressures. Because the orientation and arrangement of the templating biomolecules can be precisely

Radiation and platinum drug interaction

International Nuclear Information System (INIS)

Nias, A.H.W.

1985-01-01

The ideal platinum drug-radiation interaction would achieve radiosensitization of hypoxic tumour cells with the use of a dose of drug which is completely non-toxic to normal tissues. Electron-affinic agents are employed with this aim, but the commoner platinum drugs are only weakly electron-affinic. They do have a quasi-alkylating action however, and this DNA targeting may account for the radiosensitizing effect which occurs with both pre- and post-radiation treatments. Because toxic drug dosage is usually required for this, the evidence of the biological responses to the drug and to the radiation, as well as to the combination, requires critical analysis before any claim of true enhancement, rather than simple additivity, can be accepted. The amount of enhancement will vary with both the platinum drug dose and the time interval between drug administration and radiation. Clinical schedules may produce an increase in tumour response and/or morbidity, depending upon such dose and time relationships. (author)

CYP2S1 depletion enhances colorectal cell proliferation is associated with PGE2-mediated activation of β-catenin signaling

International Nuclear Information System (INIS)

Yang, Chao; Li, Changyuan; Li, Minle; Tong, Xuemei; Hu, Xiaowen; Yang, Xuhan; Yan, Xiaomei; He, Lin; Wan, Chunling

2015-01-01

Colorectal epithelial cancer is one of the most common cancers in the world and its 5-year survival rate is still relatively low. Cytochrome P450 (CYP) enzymes in epithelial cells lining the alimentary tract play an important role in the oxidative metabolism of a wide range of xenobiotics, including (pro-)carcinogens and endogenous compounds. Although CYP2S1, a member of CYP family, strongly expressed in many extrahepatic tissues, the role of CYP2S1 in cancer remains unclear. To investigate whether CYP2S1 involves in colorectal carcinogenesis, cell proliferation was analyzed in HCT116 cells depleted of CYP2S1 using small hairpin interfering RNA. Our data show that CYP2S1 knockdown promotes cell proliferation through increasing the level of endogenous prostaglandin E2(PGE2). PGE2, in turn, reduces phosphorylation of β-catenin and activates β-catenin signaling, which contributes to the cell proliferation. Furthermore, CYP2S1 knockdown increase tumor growth in xenograft mouse model. In brief, these results demonstrate that CYP2S1 regulates colorectal cancer growth through associated with PGE2-mediated activation of β-catenin signaling. - Highlights: • Knockdown of CYP2S1 expression improve HCT116 cell proliferation in vitro and in vivo. • Elevate PGE2 production in CYP2S1 knockdown cell is associated with its proliferation. • Elevate PGE2 level in CYP2S1 knockdown cells enhance β-catenin accumulation. • β-catenin activate TCF/LEF and target gene expression thus promote cell proliferation

CYP2S1 depletion enhances colorectal cell proliferation is associated with PGE2-mediated activation of β-catenin signaling

Energy Technology Data Exchange (ETDEWEB)

Yang, Chao [Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai 200030 (China); College of Life Science, Anhui Normal University, Wuhu 241000, Anhui (China); Li, Changyuan [College of Life Science, Anhui Normal University, Wuhu 241000, Anhui (China); Li, Minle; Tong, Xuemei [Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, Shanghai 200025 (China); Hu, Xiaowen; Yang, Xuhan [Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai 200030 (China); Yan, Xiaomei [School of Life Sciences & Biotechnology, Shanghai JiaoTong University, Shanghai 200240 (China); He, Lin, E-mail: helinhelin@gmail.com [Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai 200030 (China); Wan, Chunling, E-mail: clwan@sjtu.edu.cn [Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai 200030 (China)

2015-02-15

Colorectal epithelial cancer is one of the most common cancers in the world and its 5-year survival rate is still relatively low. Cytochrome P450 (CYP) enzymes in epithelial cells lining the alimentary tract play an important role in the oxidative metabolism of a wide range of xenobiotics, including (pro-)carcinogens and endogenous compounds. Although CYP2S1, a member of CYP family, strongly expressed in many extrahepatic tissues, the role of CYP2S1 in cancer remains unclear. To investigate whether CYP2S1 involves in colorectal carcinogenesis, cell proliferation was analyzed in HCT116 cells depleted of CYP2S1 using small hairpin interfering RNA. Our data show that CYP2S1 knockdown promotes cell proliferation through increasing the level of endogenous prostaglandin E2(PGE2). PGE2, in turn, reduces phosphorylation of β-catenin and activates β-catenin signaling, which contributes to the cell proliferation. Furthermore, CYP2S1 knockdown increase tumor growth in xenograft mouse model. In brief, these results demonstrate that CYP2S1 regulates colorectal cancer growth through associated with PGE2-mediated activation of β-catenin signaling. - Highlights: • Knockdown of CYP2S1 expression improve HCT116 cell proliferation in vitro and in vivo. • Elevate PGE2 production in CYP2S1 knockdown cell is associated with its proliferation. • Elevate PGE2 level in CYP2S1 knockdown cells enhance β-catenin accumulation. • β-catenin activate TCF/LEF and target gene expression thus promote cell proliferation.

Structures of 38-atom gold-platinum nanoalloy clusters

Energy Technology Data Exchange (ETDEWEB)

Ong, Yee Pin; Yoon, Tiem Leong [School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Lim, Thong Leng [Faculty of Engineering and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia)

2015-04-24

Bimetallic nanoclusters, such as gold-platinum nanoclusters, are nanomaterials promising wide range of applications. We perform a numerical study of 38-atom gold-platinum nanoalloy clusters, Au{sub n}Pt{sub 38−n} (0 ≤ n ≤ 38), to elucidate the geometrical structures of these clusters. The lowest-energy structures of these bimetallic nanoclusters at the semi-empirical level are obtained via a global-minimum search algorithm known as parallel tempering multi-canonical basin hopping plus genetic algorithm (PTMBHGA), in which empirical Gupta many-body potential is used to describe the inter-atomic interactions among the constituent atoms. The structures of gold-platinum nanoalloy clusters are predicted to be core-shell segregated nanoclusters. Gold atoms are observed to preferentially occupy the surface of the clusters, while platinum atoms tend to occupy the core due to the slightly smaller atomic radius of platinum as compared to gold’s. The evolution of the geometrical structure of 38-atom Au-Pt clusters displays striking similarity with that of 38-atom Au-Cu nanoalloy clusters as reported in the literature.

An experimental study on the geochemical behavior of highly siderophile elements (HSE) and metalloids (As, Se, Sb, Te, Bi) in a mss-iss-pyrite system at 650 °C: A possible magmatic origin for Co-HSE-bearing pyrite and the role of metalloid-rich phases in the fractionation of HSE

Science.gov (United States)

Cafagna, Fabio; Jugo, Pedro J.

2016-04-01

Pyrite, the most abundant sulfide in the Earth's crust, is an accessory mineral in several magmatic sulfide deposits. Although most pyrite is hydrothermal, previous experimental studies have shown that pyrite can also have a primary magmatic origin, by exsolving from monosulfide solid solution (mss) during cooling of a sulfide melt, if sulfur fugacity is sufficiently high. Pyrite from some localities has significant amounts of Co, and complex zonation in some low-melting-point chalcophile elements (LMCE), such as As, Se, Sb, Te, Bi (henceforth referred to as metalloids) and some platinum-group elements (PGE: Ru, Rh, Pd, Os, Ir, Pt). However, the origin of such pyrite and the causes of zonation are not clear. Because the distribution of some of these elements is heterogeneous and seems to be developed in concentric zones, the zonation has been interpreted to represent growth stages, some of them secondary and caused partly by hydrothermal fluids. Better constraints on the origin of Co-PGE-bearing pyrite could help unravel the geochemical processes affecting the sulfide assemblages in which it is found; thus, an experimental study was undertaken to characterize pyrite formation in magmatic sulfide environments and its relationship with metalloids and highly siderophile elements (HSE: PGE, Re, Au). Natural pyrrhotite, chalcopyrite, pentlandite and elemental S were mixed and doped with approximately 50 ppm of each HSE. A mixture of metalloids was added at 0.2 wt.% or 3 wt.% to aliquots of sulfide mixtures. Starting materials were sealed in evacuated silica tubes and fused at 1200 °C. The temperature was subsequently reduced to 750 °C (at 60 °C/h), then to 650 °C (at 0.5 °C/h) to produce relatively large euhedral pyrite crystals, then quenched. The experiments were analyzed using reflected light, SEM, EPMA and LA-ICP-MS. Experimental products contained euhedral pyrite, mss, intermediate solid solution (iss) and metalloid-rich phases, interpreted as quench product

Levels and Speciation of Platinum in Size-Fractionated Atmospheric Aerosol in Urban and Rural Sites across Europe

Science.gov (United States)

Shafer, Martin; Antkiewicz, Dagmara; Overdier, Joel; Schauer, James

2016-04-01

In this study we characterized the levels and speciation of platinum in a unique set of size-resolved atmospheric aerosol (PM) samples obtained from urban environments across Europe. From April-July 2012 we collected PM from roadside canyon, roadside motorway, and background urban sites in each of six European cities (Amsterdam, Frankfurt, London, Milan, Stockholm, and Thessaloniki). A Hi-Vol sampler was used to collect PM in three size classes (>PM7, PM7-PM3, PM3) and characterized for total platinum, soluble platinum (in a suite of physiologically relevant fluids - lung fluid (ALF), Gambles saline, 0.07M HCl, and MQ) and speciated forms (colloidal and anionic) within the soluble fractions. In addition we measured 50 other elements by SF-ICPMS, soluble ions by IC, and soluble organic carbon in the PM. Order-of-magnitude differences in air concentrations of total platinum were observed between urban sites, ranging from 4 to over 45 pg/m3; with a median level of 6 pg/m3. When platinum concentrations are normalized to PM mass the cross Europe and site-to-site variability was substantially reduced - a 3-fold variation from 200 to 600 ng/g was observed. Roadside canyon sites in London, Stockholm and Thessaloniki exhibited the highest concentrations; however levels at urban background sites were remarkably similar across the cities. Relatively consistent and low concentrations (1 to 2 pg/m3) of total platinum were observed at rural background sites across Europe. The contribution of coarse particles (>7 micron and 7-3 micron) to air concentrations of total platinum was very significant (>35% at nearly all sites). Soluble platinum fractions ranged from 2 to 6% (MQ to HCl) in rural background sites to 5 to 20% (MQ to HCl) in roadway canyon sites in London and Thessaloniki; with the extractable platinum fractions a strong function of pH. With the exception of urban canyon sites in London and Thessaloniki, soluble platinum concentrations in the fine aerosol (PM3) were all

A rapid NiS bead technique for measurements of picogram concentrations of platinum group elements (PGEs) following neutron activation

International Nuclear Information System (INIS)

Das, A.; Shukla, A.D.

1999-01-01

To measure picogram amounts of PGEs in terrestrial and extraterrestrial samples we have modified the NiS fire assay technique in conjunction with neutron activation analysis. Os, Ir and Ru are almost quantitatively concentrated in the NiS bead. The method should be applicable to other elements (Pt, Pd, and Rh) but these could not be analyzed because of the short half life of their daughter isotopes. The results also show that the chalcophhile elements like Ag also can be quantitatively estimated using this method. (author)

Chemical evolution of soil profile from humid regions: The role of the rare elements

Directory of Open Access Journals (Sweden)

Yu.N. Vodyanitskii

2016-06-01

Full Text Available Eluvial-illuvial distribution of rare metals in forest soils is expressed more vividly than the distribution of Fe and Al the more. This is applies primarily to lanthanides: Y, La, Ce. In particular, this difference is noticeable in light Al–Fe-humus podzols, where highly differentiated elements of platinum group. The type of metals exposed to eluvial-illuvial distribution depends on the mineralogical composition of the parent rock and has a pronounced regional dimension.

HydroCoil as an adjuvant to bare platinum coil treatment of 100 cerebral aneurysms

International Nuclear Information System (INIS)

Fanning, Noel F.; Berentei, Zsolt; Brennan, Paul R.; Thornton, John

2007-01-01

Introduction The overall safety of the HydroCoil, an expansile hybrid hydrogel-platinum coil, is unknown. We report a prospective observational study of our first 100 cerebral aneurysms treated with HydroCoils, focusing on safety and initial efficacy.Methods Indications, procedural complications, clinical and angiographic outcomes were recorded. Packing density, number of coils deployed and angiographic results were compared with those in a matched control group of 100 aneurysms treated solely with bare platinum coils. HydroCoil complication rates were compared to bare platinum coil rates at our institution and in published series. Results Adjuvant HydroCoil treatment led to increased mean percentage aneurysm filling compared to controls (50 ± 21% versus 27 ± 13%, P < 0.001). Immediate posttreatment angiographic results showed significantly (P < 0.001) more complete occlusions and fewer incomplete (<95%) occlusions compared to controls. Intermediate follow-up angiograms (median 7.5 months) in 63 aneurysms showed a trend towards fewer incomplete occlusions with HydroCoil treatment. There were significantly fewer major recurrences with HydroCoil treatment compared to the control treatment (9.5% versus 22.6%, P 0.046). In the adjuvant HydroCoil group, major recurrent aneurysms had significantly less percentage volume packing with HydroCoils than non-recurrent aneurysms (50.3 ± 5.0% versus 65.3 ± 18.0%, P = 0.04). There was a 12% procedural complication rate, 6% procedural morbidity and 1% mortality rate, similar to institutional and reported bare platinum coil complication rates.Conclusion HydroCoils can be safely deployed with a similar complication rate to bare platinum coils. They result in improved aneurysm filling. Intermediate follow-up angiography showed significantly fewer major recurrences. Long-term follow-up is required to confirm initial improved stability. (orig.)

Platinum group elements and gold in ferromanganese crusts from Afanasiy-Nikitin seamount, equatorial Indian Ocean: Sources and fractionation

Digital Repository Service at National Institute of Oceanography (India)

Banakar, V.K.; Hein, J.R.; Rajani, R.P.; Chodankar, A.R.

The major element relationships in ferromanganese (Fe–Mn) crusts from Afanasiy–Nikitin seamount (ANS), eastern equatorial Indian Ocean, appear to be atypical. High positive correlations (r = 0.99) between Mn/Co and Fe/Co ratios, and lack...

Determination of trace platinum by supramolecular catalytic kinetic spectrofluorimetry of {beta}-cyclodextrin-platinum-KBrO{sub 3}-salicylaldehyde furfuralhydrazone

Energy Technology Data Exchange (ETDEWEB)

Tang, Bo; Zhang, Ning; Chen, Zhen-Zhen; Kong, Qing-Cheng [Shandong Normal University, College of Chemistry, Chemical Engineering and Materials Science, Jinan (China)

2006-02-01

A supramolecular catalytic kinetic spectrofluorimetric method was developed for the determination of platinum(IV) and the possible mechanism of catalytic reaction was discussed. The method was based on the fluorescence-enhancing reaction of salicylaldehyde furfuralhydrazone (SAFH) with potassium bromate, which was catalysed by platinum(IV) in a water-ethanol medium. {beta}-Cyclodextrin ({beta}-CD) obviously sensitized the determination at pH 5.20 and 25 C. Under optimum conditions, the {beta}-CD-platinum-KBrO{sub 3}-SAFH supramolecular kinetic catalytic reaction system had excitation and emission maxima at 372 and 461 nm, respectively. The linear range of this method was 0.60-180 ng ml{sup -1} with a relative standard deviation of 1.2%, and the detection limit was 0.18 ng ml{sup -1}. Investigation of the mechanism and the effects of interferences is presented. The proposed method was applied successfully to determine trace platinum(IV) in the chemotherapeutic drug cisplatin and serum from patients with satisfactory results. (orig.)

Novel 3-(aminomethyl)naphthoquinone mannich base-platinum(IV) complexes: synthesis, characterization, electrochemical and cytotoxic studies

Energy Technology Data Exchange (ETDEWEB)

Silva, Gustavo B. da; Neves, Amanda P.; Vargas, Maria D., E-mail: mdvargas@vm.uff.br [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Instituto de Quimica; Alves, Wagner A. [Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropedica, RJ (Brazil). Departamento de Quimica; Marinho-Filho, Jose D.B.; Pessoa, Claudia; Moraes, Manoel O.; Costa-Lotufo, Leticia V. [Universidade Federal do Ceara (UFCE), Fortaleza, CE (Brazil). Centro de Ciencias da Saude. Departamento de Fisiologia e Farmacologia

2013-04-15

Three novel platinum(IV) complexes cis,cis,trans-[Pt(HL1-3)Cl{sub 2}(OH){sub 2}] 1b-3b(HL = 2-hydroxy-3-[(R{sup 1} -amino)(pyridin-2-yl)methyl]-1,4-naphthoquinone, R{sup 1} = n-butyl, HL1; n-heptyl, HL2 and n-decyl, HL3) have been obtained from the oxidation of the respective precursors cis-[Pt(HL1-3)Cl{sub 2}] 1a-3a. Cyclic voltammetry studies of 1b-3b in MeCN showed the quasi reversible naphthoquinonate (NQO{sup -}, i.e., L{sup -}) redox process and irreversible process attributed to the reduction of the Pt{sup 4+}/Pt{sup 2+} pair, at potentials about 400 mV less negative than for the cisplatin precursor cis,cis,trans-[Pt(NH{sub 3}){sub 2}Cl{sub 2}(OH){sub 2}]. Hydrogen bond interaction between the naphthoquinone 2-hydroxyl group and an axially coordinated hydroxide ligand in 1b-3b has been proposed to favor the Pt{sup 4+}/Pt{sup 2+} reduction. The cytotoxicity studies against four human cancer cell lines have shown that in general the platinum(IV) and platinum(II)derivatives exhibit the same cytotoxic profile and are all more active than cisplatin. The lowest in vitro IC{sub 50} values have been observed for 2b-3b, which bear ligands with the largest R{sup 1} groups (HL2-HL3) being the most lipophilic. Furthermore similar IC{sub 50} values for platinum(II) and platinum(IV) complexes of the same ligands have been associated with rapid in vitro reduction of the latter complexes to afford 1a-3a. (author)

The influence of platinum washing-out time on its recovery from used auto catalytic converters

Directory of Open Access Journals (Sweden)

A. Fornalczyk

2014-07-01

Full Text Available The used catalytic converters contain small amounts of precious metals. Recovery of these metals is essential for environmental and economic reasons. This work presents a method of Platinum Group Metals (PGM recovery from auto catalytic converters in which they are washed out by a liquid metal. The magneto-hydro-dynamic pump was used to force circulation of liquid metal under the influence of electromagnetic fields The influence of process time on platinum recovery was also carried out.

High performance platinum single atom electrocatalyst for oxygen reduction reaction

Science.gov (United States)

Liu, Jing; Jiao, Menggai; Lu, Lanlu; Barkholtz, Heather M.; Li, Yuping; Wang, Ying; Jiang, Luhua; Wu, Zhijian; Liu, Di-Jia; Zhuang, Lin; Ma, Chao; Zeng, Jie; Zhang, Bingsen; Su, Dangsheng; Song, Ping; Xing, Wei; Xu, Weilin; Wang, Ying; Jiang, Zheng; Sun, Gongquan

2017-07-01

For the large-scale sustainable implementation of polymer electrolyte membrane fuel cells in vehicles, high-performance electrocatalysts with low platinum consumption are desirable for use as cathode material during the oxygen reduction reaction in fuel cells. Here we report a carbon black-supported cost-effective, efficient and durable platinum single-atom electrocatalyst with carbon monoxide/methanol tolerance for the cathodic oxygen reduction reaction. The acidic single-cell with such a catalyst as cathode delivers high performance, with power density up to 680 mW cm-2 at 80 °C with a low platinum loading of 0.09 mgPt cm-2, corresponding to a platinum utilization of 0.13 gPt kW-1 in the fuel cell. Good fuel cell durability is also observed. Theoretical calculations reveal that the main effective sites on such platinum single-atom electrocatalysts are single-pyridinic-nitrogen-atom-anchored single-platinum-atom centres, which are tolerant to carbon monoxide/methanol, but highly active for the oxygen reduction reaction.

Mineral potential for nickel, copper, platinum group elements(PGE), and chromium deposits hosted in ultramafic rocks in the Islamic Republic of Mauritania (phase V, deliverable 67): Chapter G in Second projet de renforcement institutionnel du secteur minier de la République Islamique de Mauritanie (PRISM-II)

Science.gov (United States)

Taylor, Cliff D.; Marsh, Erin; Anderson, Eric D.

2015-01-01

PRISM-I summary documents mention the presence of mafic-ultramafic igneous intrusive rocks in several areas of Mauritania and a number of chromium (Cr) and copper-nickel (Cu-Ni (±Co, Au)) occurrences associated with them. Permissive geologic settings generally include greenstone belts of any age, layered mafic-ultramafic and unlayered gabbro-anorthosite intrusive complexes in cratonic settings, ophiolite complexes, flood basalt provinces, and fluid-rich shear zones cutting accumulations of mafic-ultramafic rocks. Regions of Mauritania having these characteristics that are discussed in PRISM-I texts include the Mesoarchean greenstone belts of the TasiastTijirit terrane in the southwestern Rgueïbat Shield, two separate layered ultramafic complexes in the Amsaga Complex west of Atar, serpentinized metadunites in Mesoarchean rocks of the Rgueïbat Shield in the Zednes map sheet, several lateritized annular mafic-ultramafic complexes in the Paleoproterozoic northwestern portion of the Rgueïbat Shield, and the serpentinized ophiolitic segments of the Gorgol Noir Complex in the axial portion of the southern Mauritanides. Bureau de Recherches Géologiques et Minières (BRGM) work in the “Extreme Sud” zone also suggests that small copper occurrences associated with the extensive Jurassic microgabbroic intrusive rocks in the Taoudeni Basin of southeastern Mauritania could have potential for magmatic Cu-Ni (PGE, Co, Au) sulfide mineralization. Similarly, Jurassic mafic intrusive rocks in the northeastern Taoudeni Basin may be permissive. Known magmatic Cu-Ni deposits of these types in Mauritania are few in number and some uncertainty exists as to the nature of several of the more important ones.

Platinum uptake from chloride solutions using biosorbents

Directory of Open Access Journals (Sweden)

Mehmet Hakan Morcali

2013-04-01

Full Text Available Present work investigates platinum uptake from synthetically prepared, dilute platinum-bearing solutions using biomass residues, i.e. pistachio nut shell and rice husk, which are abundant in Turkey, and provides a comparison between these two biosorbents. Effects of the different uptake parameters, sorbent dosage, contact time, temperature and pH of solution on platinum uptake (% were studied in detail on a batch sorption. Before the pistachio nut shell was activated, platinum uptake (% was poor compared to the rice husk. However, after the pistachio nut shell was activated at 1000 °C under an argon atmosphere, the platinum uptake (% increased two-fold. The pistachio nut shell (original and activated and rice husk were shown to be better than commercially available activated carbon in terms of adsorption capacity. These two sorbents have also been characterized by FTIR and SEM. Adsorption equilibrium data best complied with the Langmuir isotherm model. Maximum adsorption capacities, Qmax, at 25 °C were found to be 38.31 and 42.02 mg.g- 1for the activated pistachio nut shell and rice husk, respectively. Thermodynamic calculations using the measured ∆H°, ∆S° and ∆G° values indicate that the uptake process was spontaneous and endothermic. The experimental data were shown to be fit the pseudo-second-order kinetic model.

OFFGEL isoelectric focusing and polyacrylamide gel electrophoresis separation of platinum-binding proteins.

Science.gov (United States)

Mena, Ma Luz; Moreno-Gordaliza, Estefanía; Moraleja, Irene; Cañas, Benito; Gómez-Gómez, Ma Milagros

2011-03-04

In this work a 2D electrophoretic separation procedure able to maintain the integrity of platinum-protein bonds has been developed. The method is based on the use of sequential OFFGEL isoelectric focussing (IEF) and PAGE. A systematic study of the reagents used for PAGE, for OFFGEL-IEF separation, and post-separation treatment of gels (such as enzymatic digestion and sample preparation for MS analysis) was tackled regarding their suitability for the identification of platinum binding proteins using standard proteins incubated with cisplatin. The distribution of platinum in high and low molecular weight fractions (separated by cut-off filters) was determined by ICP-MS, which allows evaluating platinum-protein bond stability under the conditions studied. SDS-PAGE in the absence of β-mercaptoethanol or dithiotreitol preserved the platinum-protein bonds. In addition, neither the influence of the electric field during the electrophoretic separation, nor the processes of fixing, staining and destaining of proteins in the gel did result in the loss of platinum from platinum binding proteins. SDS-PAGE under non-reducing conditions provides separation of platinum-binding proteins in very narrow bands with quantitative recoveries. Different amounts of platinum-bound proteins covering the range 0.3-2.0 μg were separated and mineralised for platinum determination, showing good platinum linearity. Limits of detection for a mixture of five standard proteins incubated with cisplatin were between the range of 2.4 and 13.9 pg of platinum, which were satisfactory for their application to biological samples. Regarding OFFGEL-IEF, a denaturing solution without thiourea and without dithiotreitol is recommended. The suitability of the OFFGEL-IEF for the separation of platinum binding proteins of a kidney cytosol was demonstrated. Copyright © 2011 Elsevier B.V. All rights reserved.

Room temperature synthesis of colloidal platinum nanoparticles

Indian Academy of Sciences (India)

Unknown

platinum cation used. ... Particle size increased with low reagent concentration. ... 2,100) was added separately to the starting solution. Argon gas was bubbled in the solution for 20 min. Later, reduction of platinum ions was carried out by bubbling hydrogen gas ... plex to aquate (Cl– → H2O ligand exchange). ... copper grid.

Point defects in platinum

International Nuclear Information System (INIS)

Piercy, G.R.

1960-01-01

An investigation was made of the mobility and types of point defect introduced in platinum by deformation in liquid nitrogen, quenching into water from 1600 o C, or reactor irradiation at 50 o C. In all cases the activation energy for motion of the defect was determined from measurements of electrical resistivity. Measurements of density, hardness, and x-ray line broadening were also made there applicable. These experiments indicated that the principal defects remaining in platinum after irradiation were single vacant lattice sites and after quenching were pairs of vacant lattice sites. Those present after deformation In liquid nitrogen were single vacant lattice sites and another type of defect, perhaps interstitial atoms. (author)

Platinum uptake by the freshwater isopod Asellus Aquaticus in urban rivers

Energy Technology Data Exchange (ETDEWEB)

Rauch, S.; Morrison, G.M. [Department of Sanitary Engineering, Chalmers University of Technology, S-412 96 Goeteborg (Sweden)

1999-09-01

Platinum has been increasing in the environment as a result of emissions from catalytic converters. The platinum emitted is principally located in the vicinity of roads but might be transported to urban rivers through highway and urban run-off water. Platinum concentrations in the freshwater isopod Asellus aquaticus were measured for two urban rivers and a stormwater detention pond. Concentrations ranged from 0.04 to 12.4 {mu}g g{sup -1} for direct analysis and from 0.16 to 4.5 {mu}g g{sup -1} after depuration. Analyses of water, pore water and sediments indicate that platinum in urban rivers is mostly found in the sediments and these provide the major contribution of platinum to Asellus aquaticus. Exposure experiments showed the importance of platinum speciation for uptake.

Synthesis of platinum nanowire networks using a soft template.

Science.gov (United States)

Song, Yujiang; Garcia, Robert M; Dorin, Rachel M; Wang, Haorong; Qiu, Yan; Coker, Eric N; Steen, William A; Miller, James E; Shelnutt, John A

2007-12-01

Platinum nanowire networks have been synthesized by chemical reduction of a platinum complex using sodium borohydride in the presence of a soft template formed by cetyltrimethylammonium bromide in a two-phase water-chloroform system. The interconnected polycrystalline nanowires possess the highest surface area (53 +/- 1 m2/g) and electroactive surface area (32.4 +/- 3.6 m2/g) reported for unsupported platinum nanomaterials; the high surface area results from the small average diameter of the nanowires (2.2 nm) and the 2-10 nm pores determined by nitrogen adsorption measurements. Synthetic control over the network was achieved simply by varying the stirring rate and reagent concentrations, in some cases leading to other types of nanostructures including wormlike platinum nanoparticles. Similarly, substitution of a palladium complex for platinum gives palladium nanowire networks. A mechanism of formation of the metal nanowire networks is proposed based on confined metal growth within a soft template consisting of a network of swollen inverse wormlike micelles.

Synthesis of platinum nanowheels using a bicellar template.

Science.gov (United States)

Song, Yujiang; Dorin, Rachel M; Garcia, Robert M; Jiang, Ying-Bing; Wang, Haorong; Li, Peng; Qiu, Yan; van Swol, Frank; Miller, James E; Shelnutt, John A

2008-09-24

Disk-like surfactant bicelles provide a unique meso-structured reaction environment for templating the wet-chemical reduction of platinum(II) salt by ascorbic acid to produce platinum nanowheels. The Pt wheels are 496 +/-55 nm in diameter and possess thickened centers and radial dendritic nanosheets (about 2-nm in thickness) culminating in flared dendritic rims. The structural features of the platinum wheels arise from confined growth of platinum within the bilayer that is also limited at edges of the bicelles. The size of CTAB/FC7 bicelles is observed to evolve with the addition of Pt(II) complex and ascorbic acid. Synthetic control is demonstrated by varying the reaction parameters including metal salt concentration, temperature, and total surfactant concentration. This study opens up opportunities for the use of other inhomogeneous soft templates for synthesizing metals, metal alloys, and possibly semiconductors with complex nanostructures.

Effect of Lactobacillus reuteri on Cell Viability and PGE2 Production in Human Gingival Fibroblasts.

Science.gov (United States)

A Castiblanco, Gina; Yucel-Lindberg, Tulay; Roos, Stefan; Twetman, Svante

2017-09-01

Emerging evidence suggests that probiotic therapy can play a role in the prevention and management of oral inflammatory diseases through immunomodulation and down-regulation of the inflammatory cascade. The aim of this in vitro study was to investigate the viability of human gingival fibroblasts (HGF) and its production of prostaglandin E 2 (PGE 2 ), when exposed to supernatants of two mixed Lactobacillus reuteri strains (ATCC PTA 5289 and DSM 17938). The experiments were conducted in the presence and absence of the pro-inflammatory cytokine IL-1β. L. reuteri strains were grown and the bacterial supernatant was collected. The cell-free supernatant was diluted to concentrations equivalent to the ones produced by 0.5 to 5.0 × 10 7  CFU/mL bacteria. Cell viability was assessed with the MTT colorimetric assay and the amount of PGE 2 in the cell culture medium was determined using the monoclonal enzyme immune assay kits. Our findings showed that none of the L. reuteri supernatants were cytotoxic or affected the viability of HGF. The most concentrated bacterial supernatant stimulated the production of PGE 2 by the gingival cells in a significant way in the presence of IL-1β (p reuteri might play a role in the resolution of inflammation in HGF. Thus, our findings justify further investigations on the influence of probiotic bacteria on gingival inflammatory reactions.

Impact of humic substances on the aqueous solubility, uptake and bioaccumulation of platinum, palladium and rhodium in exposure studies with Dreissena polymorpha

International Nuclear Information System (INIS)

Sures, Bernd; Zimmermann, Sonja

2007-01-01

Zebra mussels (Dreissena polymorpha) were exposed to different types of water containing PGE salts (PtCl 4 , PdSO 4 , RhCl 3 ) to investigate the influence of humic substances on the aqueous solubility, uptake and bioaccumulation of noble metals. The results showed a time dependent decrease of the aqueous PGE concentrations in tank water for all groups. This could mainly be related to non-biological processes. The aqueous solubility of Pd and Rh was higher in humic water compared with non-chlorinated tap water, whereas Pt showed opposing results. Highest metal uptake rates and highest bioaccumulation plateaus were found for Pd, followed by Pt and Rh. Pd uptake and bioaccumulation was significantly hampered by humic substances, whose presence appear to increase Pt uptake and bioaccumulation. No clear trend emerged for Rh. Differences in effects of humic matter among the PGE may be explained by formation of metal complexes with different fractions of humic substances. - Precious metal accumulation in Dreissena polymorpha is affected by humic substances

Immiscibility of Fluid Phases at Magmatic-hydrothermal Transition: Formation of Various PGE-sulfide Mineralization for Layered Basic Intrusions

Science.gov (United States)

Zhitova, L.; Borisenko, A.; Morgunov, K.; Zhukova, I.

2007-12-01

Fluid inclusions in quartz of the Merensky Reef (Bushveld Complex, South Africa) and the Chineisky Pluton (Transbaikal Region, Russia) were studied using cryometry, microthermometry, Raman-spectroscopy, LA ICP- MS, scanning electronic microscopy, gas-chromatography and isotopic methods. This allowed us to document some examples of fluid phase separation resulting in formation of different types of PGE-sulfide mineralization for layered basic intrusions. The results obtained show at least three generations of fluid separated from boiling residual alumosilicate intercumulus liquid of the Merensky Reef. The earliest fluid phase composed of homogenous high-dense methane and nitrogen gas mixture was identified in primary gas and co-existing anomalous fluid inclusions from symplectitic quartz. The next generation, heterophase fluid, composed of brines containing a free low-dense (mostly of carbon dioxide) gas phase, was observed in primary multiphase and coexisting gas-rich inclusions of miarolitic quartz crystals. The latest generation was also a heterophase fluid (low salinity water-salt solution and free low-dense methane gas phase) found in primary water-salt and syngenetic gas inclusions from peripheral zones of miarolitic quartz crystals. For the Chineisky Pluton reduced endocontact magmatogene fluids changed to oxidized low salinity hydrothermal fluids in exocontact zone. This resulted in formation of sulfide-PGE enrichment marginal zones of intrusion. The results obtained give us a possibility to suggest that: 1) Fluid phase separation is a typical feature of magmatogene fluids for layered basic intrusions. 2) Reduced fluids can extract and transport substantial PGE and sulfide concentrations. 3) Oxidation of reduced fluids is one of the most important geochemical barriers causing abundant PGE minerals and sulfides precipitation. This in turn results in both formation of PGE reefs or enriched contact zones of layered basic intrusions. This work was supported by

Arco to enter European PGE production with new Rotterdam plant

International Nuclear Information System (INIS)

Young, I.

1993-01-01

Arco Chemical (Newtown Square, PA) will enter production of propylene glycol ethers (PGEs) in Europe by building a 70,000-m.t./year plant at its Rotterdam site. Arco's board has approved the project, with construction to begin this year and completion expected in mid-1995. 'This new plant supports the company's long-standing strategy to increase its downstream integration in value-added derivatives of propylene oxide,' says Jack Oppasser, president of Arco Chemical Europe (Maidenhead, U.K.). 'It allows the company to sustain its strong position in the growing European glycol ether market.' Arco's move represents a challenge to Dow Europe (Horgen, Switzerland), which dominates the European PGE market. Dow is Europe's biggest producer of PGEs, with its Dowanol brands commanding a share greater than 50% of the estimated 90,000-m.t./year methyl-based PGE market. This was recently boosted by completion of the expansion of its plant at Stade, Germany, from 60,000 m.t./year to 110,000 m.t./year. While Arco does not currently make PGEs in Europe, it is the second-largest supplier, with about 15,000 m.t.-20,000 m.t./year, via 'third-party manufacturing arrangements' with European producers, including BP Chemicals, and imports from its 90-million lbs/year plant at Bayport, TX. However, Arco refuses to comment on this because of 'antitrust aspects.'

Finite groups with three conjugacy class sizes of some elements

Indian Academy of Sciences (India)

Conjugacy class sizes; p-nilpotent groups; finite groups. 1. Introduction. All groups ... group G has exactly two conjugacy class sizes of elements of prime power order. .... [5] Huppert B, Character Theory of Finite Groups, de Gruyter Exp. Math.

A Change to the Platinum Publications | Poster

Science.gov (United States)

Please be advised that the Poster will no longer publish the “Platinum Publications” series listing recent NCI at Frederick publications. All published research represents a valuable addition to the fight against cancer, AIDS, and infectious diseases—thus, the “Platinum Publications” did not adequately commend all of the important work done by NCI at Frederick researchers.

In vitro permeation of platinum through African and Caucasian skin.

Science.gov (United States)

Franken, A; Eloff, F C; du Plessis, J; Badenhorst, C J; Du Plessis, J L

2015-02-03

The majority of the South African workforce are Africans, therefore potential racial differences should be considered in risk and exposure assessments in the workplace. Literature suggests African skin to be a superior barrier against permeation and irritants. Previous in vitro studies on metals only included skin from Caucasian donors, whereas this study compared the permeation of platinum through African and Caucasian skin. A donor solution of 0.3 mg/ml of potassium tetrachloroplatinate (K₂PtCl₄) dissolved in synthetic sweat was applied to the vertical Franz diffusion cells with full thickness abdominal skin. Skin from three female African and three female Caucasian donors were included (n=21). The receptor solution was removed at various intervals during the 24 h experiment, and analysed with high resolution inductively coupled plasma-mass spectrometry (ICP-MS). Skin was digested and analysed by inductively coupled plasma-optical emission spectrometry (ICP-OES). Significantly higher permeation of platinum through intact African skin (p=0.044), as well as a significantly higher mass of platinum retention in African skin in comparison with Caucasian skin (p=0.002) occurred. Significant inter-donor variation was found in both racial groups (pskin and further investigation is necessary to explain the higher permeation through African skin. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Dissolution of Platinum in Hydrochloric Acid Under Industrial-Scale Alternating Current Polarization

Science.gov (United States)

Myrzabekov, B. E.; Bayeshov, A. B.; Makhanbetov, A. B.; Mishra, B.; Baigenzhenov, O. S.

2018-02-01

The electrochemical behavior of platinum in a hydrochloric acid solution under polarization by an industrial-scale alternating current has been investigated. For the electrical dissolution of platinum, titanium is used as an auxiliary electrode, which increases the yield of platinum dissolution by 12.5 pct. The influence of the concentration of hydrochloric acid, the current densities of the platinum and titanium electrodes, and the temperature of the electrolyte on the efficiency of the process of dissolving platinum have all been studied.

Evaluation of the antitumor activity of platinum nanoparticles in the treatment of hepatocellular carcinoma induced in rats.

Science.gov (United States)

Medhat, Amina; Mansour, Somaya; El-Sonbaty, Sawsan; Kandil, Eman; Mahmoud, Mustafa

2017-07-01

This study aimed to evaluate the antitumor activity of platinum nanoparticles compared with cis-platin both in vitro and in vivo in the treatment of hepatocellular carcinoma induced in rats. The treatment efficacy of platinum nanoparticles was evaluated by measuring antioxidant activities against oxidative stress caused by diethylnitrosamine in liver tissue. The measurements included reduced glutathione content and superoxide dismutase activity, as well as malondialdehyde level. Liver function tests were also determined, in addition to the evaluation of serum alpha-fetoprotein, caspase-3, and cytochrome c in liver tissue. Total RNA extraction from liver tissue samples was also done for the relative quantification of B-cell lymphoma 2, matrix metallopeptidase 9, and tumor protein p53 genes. Histopathological examination was also performed for liver tissue. Results showed that platinum nanoparticles are more potent than cis-platin in treatment of hepatocellular carcinoma induced by diethylnitrosamine in rats as it ameliorated the investigated parameters toward normal control animals. These findings were well appreciated with histopathological studies of diethylnitrosamine group treated with platinum nanoparticles, suggesting that platinum nanoparticles can serve as a good therapeutic agent for the treatment of hepatocellular carcinoma which should attract further studies.

Electrochemical behaviour of gamma hydroxybutyric acid at a platinum electrode in acidic medium

International Nuclear Information System (INIS)

Jiménez-Pérez, R.; Sevilla, J.M.; Pineda, T.; Blázquez, M.; González-Rodríguez, J.

2013-01-01

Highlights: • This is the first reported electrochemical study of the behaviour of GHB. • The first study of the interaction of GHB on solid electrodes. • The GHB oxidation process in platinum electrodes is a complex process. • Re-dissolution and reduction of Pt oxides and oxidation of the GHB OH group. • The oxidation process is also influenced by pH and GHB concentration. -- Abstract: The electrooxidation of gamma hydroxybutyric acid (GHB) on a polycrystalline platinum electrode is studied by cyclic voltammetry in acidic medium. Two oxidation peaks, A and B, are obtained in the positive scan within the potential range of the double layer region and of the platinum oxide region, respectively. In the negative going potential sweep an inverted oxidation peak with an onset partially overlapping with the tail of the cathodic peak for the reduction of the platinum oxide formed during the anodic scan is obtained (peak C). This inverted peak can be observed at a potential close to +0.2 V (vs Ag/AgCl at pH 2) and separated 0.4 and 0.8 V from the two other oxidation peaks obtained during the anodic scan and in such conditions that the surface is particularly activated to favour this electrochemical process. The response obtained in the electronic current for the different peaks when GHB concentration and scan rate were changed to allows inferring that these are the result of a potential dependent mechanism. The behaviour observed is according with the oxidation of the alcohol group to the corresponding aldehyde and carboxylic acid (succinic acid) as main products

Real Elements and p-Nilpotence of Finite Groups

Directory of Open Access Journals (Sweden)

Adolfo Ballester-Bolinches

2016-12-01

Full Text Available Our first main result proves that every element of order 4 of a Sylow 2-subgroup S of a minimal non-2-nilpotent group G, is a real element of S. This allows to give a character-free proof of a theorem due to Isaacs and Navarro (see [9, Theorem B]. As an application, the authors show a common extension of the p-nilpotence criteria proved in [3] and [9].

Long-term program for research and development of group separation and disintegration techniques

International Nuclear Information System (INIS)

1988-01-01

In Japan, the basic guidelines state that high-level radioactive wastes released from reprocessing of spent fuel should be processed into stable solid material, followed by storage for cooling for 30-50 years and disposal in the ground at a depth of several hundreds of meters. The Long-Term Program for Research and Development of Group Separation and Disintegration Techniques is aimed at efficient disposal of high-level wastes, reutilization of useful substances contained, and improved safety. Important processes include separation of nuclides (group separation, individual nuclide separation) and conversion (disintegration) of long-lived nuclides into short-lived or non-radioactive one. These processes can reduce the volume of high-level wastes to be left for final disposal. Research and development projects have been under way to provide techniques to separate high-level waste substances into four groups (transuranic elements, strontium/cesium, technetium/platinum group elements, and others). These projects also cover recovery of useful metals and efficient utilization of separated substances. For disintegration, conceptual studies have been carried out for the application of fast neutron beams to conversion of long half-life transuranium elements into short half-life or non-radioactive elements. (N.K.)

Preparation of platinum/iridium scanning probe microscopy tips

DEFF Research Database (Denmark)

Sørensen, Alexis Hammer; Hvid, U.; Mortensen, M.W.

1999-01-01

oxide layer. In order to explain the relatively high etching rates observed for the otherwise noble metal platinum we suggest that besides anodic corrosion of the platinum by the electrolyte containing chloride ions, a different etching mechanism causes a substantial increase of the etching rate...

Exosomes as mediators of platinum resistance in ovarian cancer.

Science.gov (United States)

Crow, Jennifer; Atay, Safinur; Banskota, Samagya; Artale, Brittany; Schmitt, Sarah; Godwin, Andrew K

2017-02-14

Exosomes have been implicated in the cell-cell transfer of oncogenic proteins and genetic material. We speculated this may be one mechanism by which an intrinsically platinum-resistant population of epithelial ovarian cancer (EOC) cells imparts its influence on surrounding tumor cells. To explore this possibility we utilized a platinum-sensitive cell line, A2780 and exosomes derived from its resistant subclones, and an unselected, platinum-resistant EOC line, OVCAR10. A2780 cells demonstrate a ~2-fold increase in viability upon treatment with carboplatin when pre-exposed to exosomes from platinum-resistant cells as compared to controls. This coincided with increased epithelial to mesenchymal transition (EMT). DNA sequencing of EOC cell lines revealed previously unreported somatic mutations in the Mothers Against Decapentaplegic Homolog 4 (SMAD4) within platinum-resistant cells. A2780 cells engineered to exogenously express these SMAD4 mutations demonstrate up-regulation of EMT markers following carboplatin treatment, are more resistant to carboplatin, and release exosomes which impart a ~1.7-fold increase in resistance in naive A2780 recipient cells as compared to controls. These studies provide the first evidence that acquired SMAD4 mutations enhance the chemo-resistance profile of EOC and present a novel mechanism in which exchange of tumor-derived exosomes perpetuates an EMT phenotype, leading to the development of subpopulations of platinum-refractory cells.

Oxidative Addition and Reductive Elimination at Main-Group Element Centers.

Science.gov (United States)

Chu, Terry; Nikonov, Georgii I

2018-04-11

Oxidative addition and reductive elimination are key steps in a wide variety of catalytic reactions mediated by transition-metal complexes. Historically, this reactivity has been considered to be the exclusive domain of d-block elements. However, this paradigm has changed in recent years with the demonstration of transition-metal-like reactivity by main-group compounds. This Review highlights the substantial progress achieved in the past decade for the activation of robust single bonds by main-group compounds and the more recently realized activation of multiple bonds by these elements. We also discuss the significant discovery of reversible activation of single bonds and distinct examples of reductive elimination at main-group element centers. The review consists of three major parts, starting with oxidative addition of single bonds, proceeding to cleavage of multiple bonds, and culminated by the discussion of reversible bond activation and reductive elimination. Within each subsection, the discussion is arranged according to the type of bond being cleaved or formed and considers elements from the left to the right of each period and down each group of the periodic table. The majority of results discussed in this Review come from the past decade; however, earlier reports are also included to ensure completeness.

One-step electrochemically-codeposited polyaniline-platinum for dye-sensitized solar cell applications

Energy Technology Data Exchange (ETDEWEB)

Thiangkaew, Anongnad; Keothongkham, Khamsone; Maiaugree, Wasan; Jarernboon, Wirat [Khon Kaen University, Khon Kaen (Thailand); Kamwanna, Teerasak; Pimanpang, Samuk; Amornkitbamrung, Vittaya [Khon Kaen University, Khon Kaen (Thailand); Nanotec-KKU Center of Excellence on Advanced Nanomaterials for Energy Production and Storage, Khon Kaen (Thailand)

2014-05-15

Platinum, polyaniline and composite polyaniline-platinum films were coated on conductive glass by using electrochemical deposition. They were then used as dye-sensitized solar cell counter electrodes. The efficiencies of platinum, polyaniline and composite polyaniline-platinum cells were 2.47, 4.47 and 6.62%, respectively. The improvement of composite polyaniline-platinum solar cell efficiency over pure polyaniline and platinum cells is because of an increase in the film's catalytic activity and a decrease in charge-transfer resistance between its counter electrode and electrolyte, as observed by using cyclic voltammogram and electrochemical impedance spectroscopy measurements, respectively. Co-deposition of polyaniline and Pt catalysts was confirmed by the presence of Pt and N peaks in the X-ray photoelectron spectroscopy spectrum.

Stabilization of 200-atom platinum nanoparticles by organosilane fragments

KAUST Repository

Pelzer, Katrin

2011-04-19

Three\\'s a charm: Platinum nanoparticles of 2 nm diameter and containing approximately 200 atoms covered with n-octylsilyl groups (see picture, right; Pt blue, Si red, C gray, H turquoise) form when [Pt(dba)2] (dba=dibenzylideneacetone) decomposes in the presence of n-octylsilane. The particles adopt a cuboctahedral structure with an edge length of three atoms. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stabilization of 200-atom platinum nanoparticles by organosilane fragments

KAUST Repository

Pelzer, Katrin; Hä vecker, Michael; Boualleg, Malika; Candy, Jean Pierre; Basset, Jean-Marie

2011-01-01

Three's a charm: Platinum nanoparticles of 2 nm diameter and containing approximately 200 atoms covered with n-octylsilyl groups (see picture, right; Pt blue, Si red, C gray, H turquoise) form when [Pt(dba)2] (dba=dibenzylideneacetone) decomposes in the presence of n-octylsilane. The particles adopt a cuboctahedral structure with an edge length of three atoms. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Phase-field model for deposition process of platinum nanoparticles on carbon substrate

International Nuclear Information System (INIS)

Yamakawa, S; Hyodo, S; Okazaki-Maeda, K; Kohyama, M

2008-01-01

Platinum supported on a carbon carrier is widely used as a catalyst for polymer electrolyte membrane fuel cells. The catalytic activity is significantly affected by the size distribution and morphologies of the platinum particles. The objective of this study is to extend the phase-field approach to describe the formation process of platinum particles onto the substrate. The microstructural evolution of a nanoparticle was represented by the temporal evolution of the field variables related to the platinum concentration, long-range crystallographic ordering and phase transition. First-principles calculations were performed in order to estimate the interaction energies between several different types of platinum clusters and a graphene sheet. The platinum density profile concentrated over the substrate surface led to the formation of three-dimensional islands in accordance with the Volmer-Weber mode of growth. The size distributions of the platinum particles were sensitive to the heterogeneity of the substrate surface and to the competitive nucleation and growth processes

An impending platinum crisis and its implications for the future of the automobile

International Nuclear Information System (INIS)

Yang, C.-J.

2009-01-01

The global demand for platinum has consistently outgrown supply in the past decade. This trend likely will continue and the imbalance may possibly escalate into a crisis. Platinum plays pivotal roles in both conventional automobile emissions control and the envisioned hydrogen economy. A platinum crisis would have profound implications on energy and environment. On the one hand, inadequate platinum supply will prevent widespread commercialization of hydrogen fuel-cell vehicles. On the other hand, expensive platinum may enhance the competitiveness of hybrid, plug-in hybrid, and battery-powered electric cars. Policymakers should weigh the potential impacts of a platinum crisis in energy policy.

Effect of Lactobacillus reuteri on Cell Viability and PGE2 Production in Human Gingival Fibroblasts

DEFF Research Database (Denmark)

Castiblanco, Gina A.; Yucel-Lindberg, Tulay; Roos, Stefan

2017-01-01

Emerging evidence suggests that probiotic therapy can play a role in the prevention and management of oral inflammatory diseases through immunomodulation and down-regulation of the inflammatory cascade. The aim of this in vitro study was to investigate the viability of human gingival fibroblasts...... (HGF) and its production of prostaglandin E2 (PGE2), when exposed to supernatants of two mixed Lactobacillus reuteri strains (ATCC PTA 5289 and DSM 17938). The experiments were conducted in the presence and absence of the pro-inflammatory cytokine IL-1β. L. reuteri strains were grown and the bacterial...... immune assay kits. Our findings showed that none of the L. reuteri supernatants were cytotoxic or affected the viability of HGF. The most concentrated bacterial supernatant stimulated the production of PGE2 by the gingival cells in a significant way in the presence of IL-1β (p

Platinum boride nanowires: Synthesis and characterization

International Nuclear Information System (INIS)

Ding Zhanhui; Qiu Lixia; Zhang Jian; Yao Bin; Cui Tian; Guan Weiming; Zheng Weitao; Wang Wenquan; Zhao Xudong; Liu Xiaoyang

2012-01-01

Highlights: ► Platinum boride nanowires have been synthesized via the direct current arc discharge method. ► XRD, TEM and SAED indicate that the nanowires are single-crystal PtB. ► Two broad photoluminescence emission peaks at about 586 nm and 626 nm have been observed in the PL spectroscopy of PtB nanowires. - Abstract: Platinum boride (PtB) nanowires have been successfully fabricated with direct current arc discharge method using a milled mixture of platinum (Pt) and boron nitride (BN) powders. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the compositions, morphology, and structures of the samples. The results show that PtB nanowires are 30–50 nm thick and 20–30 μm long. TEM and selected area electron diffraction (SAED) patterns identify that the PtB nanowires are single-crystalline in nature. A growth mechanism based on vapor–liquid–solid (VLS) process is proposed for the formation of nanowires.

Adenosine triphosphate-based chemotherapy response assay (ATP-CRA)-guided platinum-based 2-drug chemotherapy for unresectable nonsmall-cell lung cancer.

Science.gov (United States)

Moon, Yong Wha; Choi, Sung Ho; Kim, Yong Tai; Sohn, Joo Hyuk; Chang, Joon; Kim, Se Kyu; Park, Moo Suk; Chung, Kyung Young; Lee, Hyoun Ju; Kim, Joo-Hang

2007-05-01

The study investigated correlations between adenosine triphosphate / chemotherapy response assay (ATP-CRA) and clinical outcomes after ATP-CRA-guided platinum-based chemotherapy for unresectable nonsmall-cell lung cancer (NSCLC). The authors performed an in vitro chemosensitivity test, ATP-CRA, to evaluate the chemosensitivities of anticancer drugs such as cisplatin, carboplatin, paclitaxel, docetaxel, gemcitabine, and vinorelbine for chemonaive, unresectable NSCLC. The cell death rate was determined by measuring the intracellular ATP levels of drug-exposed cells compared with untreated controls. A sensitive drug was defined as a drug producing 30% or more reduction in ATP compared with untreated controls. Assay-guided platinum-based 2-drug chemotherapy was given to patients with pathologically confirmed NSCLC. Thirty-four patients were enrolled. Thirty tumor specimens were obtained by bronchoscopic biopsies and 4 obtained surgically. The median age was 61 years and 27 patients had an Eastern Cooperative Oncology Group (ECOG) performance status of 0-1. The response rate was 43.8%. At a median follow-up period of 16.9 months, the median progression-free and overall survivals were 3.6 and 11.2 months, respectively. Patients were dichotomized into the platinum-sensitive (S; 20 patients) and resistant (R; 14 patients) groups. The positive/negative predictive values were 61.1% and 78.6% with a predictive accuracy of 68.8%. Although without significant differences in pretreatment parameters, the S-group showed better clinical response (P=.036), longer progression-free survival (P=.060), and longer overall survival (P=.025). Despite using bronchoscopic biopsied specimens, ATP-CRA and clinical outcomes correlated well after assay-guided platinum-based 2-drug chemotherapy for unresectable NSCLC. There was a favorable response and survival in the platinum-sensitive vs resistant groups. Copyright (c) 2007 American Cancer Society

Determination of trace and ultra-trace elements in Dergaon meteorite by inductively coupled plasma mass spectrometry

International Nuclear Information System (INIS)

Balaram, V.; Gnaneswara Rao, T.; Anjaiah, K.V.; Phukon, N.; Majumdar, A.C.

2003-01-01

In this paper, a detailed methodology for high precision measurement of several trace and ultra-trace elements including REE and PGE have been presented using effective sample preparation techniques and inductively coupled plasma mass spectrometry. Discussion is focussed on aspects, such as total dissolution and recovery of all elements, minimization of oxide and doubly-charged and other polyatomic ion interferences, calibration by matrix matching standards, accuracy and precision

Activity targets for nanostructured platinum-group-metal-free catalysts in hydroxide exchange membrane fuel cells

Science.gov (United States)

Setzler, Brian P.; Zhuang, Zhongbin; Wittkopf, Jarrid A.; Yan, Yushan

2016-12-01

Fuel cells are the zero-emission automotive power source that best preserves the advantages of gasoline automobiles: low upfront cost, long driving range and fast refuelling. To make fuel-cell cars a reality, the US Department of Energy has set a fuel cell system cost target of US$30 kW-1 in the long-term, which equates to US$2,400 per vehicle, excluding several major powertrain components (in comparison, a basic, but complete, internal combustion engine system costs approximately US$3,000). To date, most research for automotive applications has focused on proton exchange membrane fuel cells (PEMFCs), because these systems have demonstrated the highest power density. Recently, however, an alternative technology, hydroxide exchange membrane fuel cells (HEMFCs), has gained significant attention, because of the possibility to use stable platinum-group-metal-free catalysts, with inherent, long-term cost advantages. In this Perspective, we discuss the cost profile of PEMFCs and the advantages offered by HEMFCs. In particular, we discuss catalyst development needs for HEMFCs and set catalyst activity targets to achieve performance parity with state-of-the-art automotive PEMFCs. Meeting these targets requires careful optimization of nanostructures to pack high surface areas into a small volume, while maintaining high area-specific activity and favourable pore-transport properties.

Release of LHRH-activity from human fetal membranes upon exposure to PGE/sub 2/, oxytocin and isoproterenol

Energy Technology Data Exchange (ETDEWEB)

Poisner, A.M.; Poisner, R.; Becca, C.R.; Conn, P.M.

1986-03-01

The authors have previously reported that superfused chorion laeve (fetal membranes) release LHRH-like immunoreactivity upon exposure to angiotensin II. They have now studied the effects of other agonists on the release of LHRH-activity and something of its chemical nature. Fetal membranes were obtained from placentas delivered by cesarean section, the amnion stripped from the chorion, and the chorion superfused in an Amicon thin-channel device with the maternal surface facing up. The whole device was submerged in a 37 C water bath and perfused with a modified Locke's solution at 0.4 - 1.0 ml/min. LHRH-activity was measured by radioimmunoassay using three different antisera against LHRH. The release of LHRH-activity was stimulated by 6-10 min exposure to PGE/sub 2/, oxytocin, and isoproterenol. Extracts of chorion were studied using gel filtration on Sephacryl S-200 and ultrafiltration with Amicon PM-10 filters. The bulk of the LHRH-activity appeared as a higher molecular weight form (about 70,000 daltons). Since oxytocin has been reported to release PGE/sub 2/ from chorion, it may release LHRH-activity by virtue of liberating endogenous PGE/sub 2/. The chemical nature of the LHRH-activity is presently under investigation.

Electrical Discharge Platinum Machining Optimization Using Stefan Problem Solutions

Directory of Open Access Journals (Sweden)

I. B. Stavitskiy

2015-01-01

Full Text Available The article presents the theoretical study results of platinum workability by electrical discharge machining (EDM, based on the solution of the thermal problem of moving the boundary of material change phase, i.e. Stefan problem. The problem solution enables defining the surface melt penetration of the material under the heat flow proceeding from the time of its action and the physical properties of the processed material. To determine the rational EDM operating conditions of platinum the article suggests relating its workability with machinability of materials, for which the rational EDM operating conditions are, currently, defined. It is shown that at low densities of the heat flow corresponding to the finishing EDM operating conditions, the processing conditions used for steel 45 are appropriate for platinum machining; with EDM at higher heat flow densities (e.g. 50 GW / m2 for this purpose copper processing conditions are used; at the high heat flow densities corresponding to heavy roughing EDM it is reasonable to use tungsten processing conditions. The article also represents how the minimum width of the current pulses, at which platinum starts melting and, accordingly, the EDM process becomes possible, depends on the heat flow density. It is shown that the processing of platinum is expedient at a pulse width corresponding to the values, called the effective pulse width. Exceeding these values does not lead to a substantial increase in removal of material per pulse, but considerably reduces the maximum repetition rate and therefore, the EDM capacity. The paper shows the effective pulse width versus the heat flow density. It also presents the dependences of the maximum platinum surface melt penetration and the corresponding pulse width on the heat flow density. Results obtained using solutions of the Stephen heat problem can be used to optimize EDM operating conditions of platinum machining.

Chemotherapy alters monocyte differentiation to favor generation of cancer-supporting M2 macrophages in the tumor microenvironment

NARCIS (Netherlands)

Dijkgraaf, Eveline M.; Heusinkveld, Moniek; Tummers, Bart; Vogelpoel, Lisa T. C.; Goedemans, Renske; Jha, Veena; Nortier, Johan W. R.; Welters, Marij J. P.; Kroep, Judith R.; van der Burg, Sjoerd H.

2013-01-01

Current therapy of gynecologic malignancies consists of platinum-containing chemotherapy. Resistance to therapy is associated with increased levels of interleukin (IL)-6 and prostaglandin E2 (PGE(2)), 2 inflammatory mediators known to skew differentiation of monocytes to tumor-promoting M2

The RSC Faraday prize lecture of 1989 on platinum.

Science.gov (United States)

Thomas, John Meurig

2017-08-25

In 1861, Michael Faraday gave one of his last Friday Evening Discourses at the Royal Institution of Great Britain, London, on platinum, which he described as "this beautiful, magnificent and valuable metal". More than a hundred and twenty years later (in 1989), the author re-enacted, at the Royal Institution, many of the demonstrations that Faraday carried out in his memorable Discourse. This article outlines many of Faraday's views on, and experiments with, platinum. It also describes the continuing importance and utilization of platinum, both as perceived in 1989 and from present perspectives.

Impact of humic substances on the aqueous solubility, uptake and bioaccumulation of platinum, palladium and rhodium in exposure studies with Dreissena polymorpha

Energy Technology Data Exchange (ETDEWEB)

Sures, Bernd [Department of Applied Zoology/Hydrobiology, University of Duisburg-Essen, D-45177 Essen (Germany)]. E-mail: bernd.sures@uni-due.de; Zimmermann, Sonja [Department of Applied Zoology/Hydrobiology, University of Duisburg-Essen, D-45177 Essen (Germany)

2007-03-15

Zebra mussels (Dreissena polymorpha) were exposed to different types of water containing PGE salts (PtCl{sub 4}, PdSO{sub 4}, RhCl{sub 3}) to investigate the influence of humic substances on the aqueous solubility, uptake and bioaccumulation of noble metals. The results showed a time dependent decrease of the aqueous PGE concentrations in tank water for all groups. This could mainly be related to non-biological processes. The aqueous solubility of Pd and Rh was higher in humic water compared with non-chlorinated tap water, whereas Pt showed opposing results. Highest metal uptake rates and highest bioaccumulation plateaus were found for Pd, followed by Pt and Rh. Pd uptake and bioaccumulation was significantly hampered by humic substances, whose presence appear to increase Pt uptake and bioaccumulation. No clear trend emerged for Rh. Differences in effects of humic matter among the PGE may be explained by formation of metal complexes with different fractions of humic substances. - Precious metal accumulation in Dreissena polymorpha is affected by humic substances.

Studies on Romanian archaeological objects using atomic methods: the cases of the Pietroasa hoard and Cucuteni ceramics

International Nuclear Information System (INIS)

Constantinescu, B.; Cojocaru, V.; Dumitriu, D.E.; Bugoi, R.; Seclaman, D.; Popovici, D.; Grambole, D.; Herrmann, F.

2004-01-01

Five fragments of ancient gold objects coming from the famous Pietroasa 'Closca cu Puii de aur' (The Golden Brood Hen with its Chickens') Romanian hoard were analyzed using micro-PIXE (Particle Induced X-ray Emission) technique. The purpose of the study was to clarify the metal provenance. To reach this goal, the presence of trace elements (Cu, Te, Cr, Nb, Ta) and PGE (Platinum Group Elements) was analyzed. The existence of inclusions (micrometer size areas of composition different from the surroundings) was also checked. We found Ta, Nb, and Cr inclusions on three samples and Pd inclusions on one sample. The measurements led to some conclusions for possible three gold ore sources of the Pietroasa treasury: South-Ural Mountains, Nubia (Sudan) deposits and Roman imperial coins. The composition of black, white and red pigments from the Neolithic Cucuteni ceramics shards found in Moldavia and South-Eastern Transylvania was determined using Synchrotron Radiation induced X-ray Powder Diffraction (SR-XRD) at MAX II synchrotron in Lund, Sweden. Different manganese oxides, animal carbon and graphite were detected in the black pigments, calcite and aluminium silicates in the white pigments and iron oxides (mainly hematite) in the red pigments. (authors)

Blood hsCRP And PGE2 Content With Clinical Outcome Using Modified Fenestrat Restorative Spinoplasty Better Than Lamonectomy-Fusion In Lumbar Stenosis

Directory of Open Access Journals (Sweden)

T Mahadewa

2012-05-01

Full Text Available Objective: Modified Fenestration-Restorative Spinoplasty (MFRS technique is an alternative to lumbar stenosis treatment, providing the equal decompression comparing with laminectomy techniques, without the implant, less expensive and complication rates. The purpose of this study was to determine which technique gives better inflammation and clinical outcome based on high sensitive C-Reactive Protein biomarker (hsCRP and Prostaglandin E2 (PGE 2, Visual Analog Scale (VAS of the day 7th postsurgery and ODI scores 3rd month post surgery. Methods: This study design is an experimental pretest-posttest randomized control group design. Results: This study results showed that the mean levels of hsCRP day 7th postsurgery were differ significantly between MFRS (23,09 ± 15,3 mg/L compared to LF (39,53 ± 24,4 mg/L. Likewise for the mean levels of PGE2 day 7th postsurgery were differ significantly between MFRS (491,39 ± 528,5 pg/ml compared to LF (1103,7 ± 1033,6 pg/ml at the significance level of p <0.05. MFRS clinical outcomes better than LF (p <0.05, for means of VAS value day 7th postsurgery and ODI score 3rd month postsurgery. Perioperative variable analysis shows that MFRS was better than LF in: length of surgery, blood loss, postsurgery Hb and patient length of stay (p<0,05. Conclusions: MFRS technique is an alternative technique of lumbar stenosis treatment better than the LF, in terms of improved levels of hsCRP and PGE2, leading to faster clinical outcomes improvement, less complications and lower costs. MFRS technique should be used as a treatment of lumbar stenosis.

Linking precious metal enrichment and halogen cycling in mafic magmatic systems: insights from the Rum layered intrusion, NW Scotland

Science.gov (United States)

Kelly, A. P.; O'Driscoll, B.; Clay, P. L.; Burgess, R.

2017-12-01

Layered intrusions host the world's largest known concentrations of the platinum-group elements (PGE). Emphasis has been attached to the role of halogen-bearing fluids in concentrating the precious metals, but whether this occurs at the magmatic stage, or via subsequent metasomatism, is actively debated. One obstacle to progress has been the analytical difficulty of measuring low abundances of the halogens in the cumulate products of layered intrusions. To elucidate the importance of the halogens in facilitating PGE-mineralisation, as well as fingerprint halogen provenance and assess the importance of halogen cycling in mafic magma systems more generally, a suite of samples encompassing different stages of activity of the Palaeogene Rum layered intrusion was investigated. Halogen abundances were measured by neutron irradiation noble gas mass spectrometric analysis, permitting the detection of relatively low (ppm-ppb) abundances of Cl, Br and I in mg-sized samples. The samples include PGE-enriched chromite seams, various cumulates (e.g., peridotites), picrites (approximating the Rum parental magma), and pegmatites representing volatile-rich melts that circulated the intrusion at a late-stage in its solidification history. The new data reveal that PGE-bearing chromite seams contain relatively low Cl concentrations (2-3 ppm), with high molar ratios of Br/Cl and I/Cl (0.005 and 0.009, respectively). The picrites and cumulates have Br/Cl and I/Cl ratios close to sub-continental lithospheric mantle values of approximately 0.0013 and 0.00002, respectively, and thus likely reflect the Rum magma source region. A positive correlation between Cl and Br signifies comparable partitioning behaviour in all samples. However, I is more variable, displaying a positive correlation with Cl for more primitive samples (e.g. picrite and peridotite), and seemingly decoupling from Br and Cl in chromite seams and pegmatites. The relative enrichment of I over Cl in the chromite seams points

Single-Atom Catalyst of Platinum Supported on Titanium Nitride for Selective Electrochemical Reactions.

Science.gov (United States)

Yang, Sungeun; Kim, Jiwhan; Tak, Young Joo; Soon, Aloysius; Lee, Hyunjoo

2016-02-05

As a catalyst, single-atom platinum may provide an ideal structure for platinum minimization. Herein, a single-atom catalyst of platinum supported on titanium nitride nanoparticles were successfully prepared with the aid of chlorine ligands. Unlike platinum nanoparticles, the single-atom active sites predominantly produced hydrogen peroxide in the electrochemical oxygen reduction with the highest mass activity reported so far. The electrocatalytic oxidation of small organic molecules, such as formic acid and methanol, also exhibited unique selectivity on the single-atom platinum catalyst. A lack of platinum ensemble sites changed the reaction pathway for the oxygen-reduction reaction toward a two-electron pathway and formic acid oxidation toward direct dehydrogenation, and also induced no activity for the methanol oxidation. This work demonstrates that single-atom platinum can be an efficient electrocatalyst with high mass activity and unique selectivity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cold and semi-hot tests of 4-group partitioning process at NUCEF

Energy Technology Data Exchange (ETDEWEB)

Morita, Yasuji; Yamaguchi, Isoo; Fujiwara, Takeshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Mizoguchi, Kenichi [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan); Kubota, Masumitsu [Research Organization for Information Science and Technology, Tokai, Ibaraki (Japan)

2000-06-01

The 4-Group Partitioning Process was tested in the Partitioning Test Facility installed in a hot cell at NUCEF (Nuclear Fuel Cycle Safety Engineering Research Facility) using simulated high-level liquid waste (HLLW) or the simulated HLLW added with a small amount of real HLLW and Tc. Behavior of each element was examined in a series of the following separation steps: pretreatment for HLLW to prepare the feed solution to extraction step, extraction with diisodecylphosphoric acid for the separation of transuranium elements, precipitation by denitration and adsorption step with active carbon for the separation of Tc and platinum group metals, and adsorption with inorganic ion exchangers for the separation of Sr and Cs. It was confined that each element behaved as expected. More than 99.99% of Am were extracted with DIDPA and 99.92% of Am were back-extracted with 4 M nitric acid. In the precipitation step by denitration, ratio of Tc precipitated was 96.2%. The present tests confined the expected performance of each equipment in the Partitioning Test Facility for the separation of elements and gave useful data for the comparison of element behavior with a result of a partitioning test using real HLLW. (author)

Bimetallic alloy electrocatalysts with multilayered platinum-skin surfaces

Science.gov (United States)

Stamenkovic, Vojislav R.; Wang, Chao; Markovic, Nenad M.

2016-01-26

Compositions and methods of preparing a bimetallic alloy having enhanced electrocatalytic properties are provided. The composition comprises a PtNi substrate having a surface layer, a near-surface layer, and an inner layer, where the surface layer comprises a nickel-depleted composition, such that the surface layer comprises a platinum skin having at least one atomic layer of platinum.

Origin and mixing timescale of Earth's late veneer

Science.gov (United States)

Prescher, C.; Allu Peddinti, D.; Bell, E. A.; Bello, L.; Cernok, A.; Ghosh, N.; Tucker, J.; Wielicki, M. M.; Zahnle, K. J.

2012-12-01

Experimental studies on the partitioning behavior of highly siderophile elements (HSE) between silicate and metallic melts imply that the Earth's mantle should have been highly depleted in these elements by core formation in an early magma ocean. However, present HSE contents of the Earth's mantle are ~3 orders of magnitude higher than that expected by experiments. The apparent over-abundance of HSE has commonly been explained by the addition of meteoritic material in the "late veneer" which describes the exogenous mass addition following the moon forming impact and concluding with the late heavy bombardment at ~3.8-3.9 Ga. The strongest evidence for this theory is that the platinum group element (PGE) contents in today's mantle are present in chondritic relative abundances, as opposed to a fractionated pattern expected with metal-silicate partitioning. Archean komatiites indicate that the PGE content of the Earth's mantle increased from about half their present abundances at 3.5 Ga to their present abundances at 2.9 Ga. This secular increase in PGE content suggests a progressive mixing of the late veneer material into the Earth's mantle. However, this time scale also implies that the whole mantle was relatively well mixed by 2.9 Ga. We use a compilation of existing isotopic and trace element data in order to constrain the origin and composition of the late veneer. We use PGE abundances, W abundances and W isotopic compositions in chondritic meteorites and the primitive upper mantle to compute the amount of mass delivered during the late veneer and find the late veneer mass to be ~0.6 % the mass of the bulk silicate Earth (consistent with earlier estimates). We also use the 187Re-187Os and 190Pt-186Os systems to constrain the composition and timing of delivery of the impacting population. We model the efficiency of mantle mixing in this time frame by using 3-dimensional numerical geodynamical simulations and geochemical constraints. Initial parameters include the

Studies on the distribution of platinum in tumour-bearing rats after the administration of platinum co-ordination complexes used in cancer chemotherapy

International Nuclear Information System (INIS)

Zeisler, R.; Lux, F.; Beck, W.

1979-01-01

Platinum co-ordination complexes like dichlorodiamineplatinum(II) (DDP) feature broad spectrum antitumour activity which, however, is marred by a certain toxicity related especially to renal tubular damage. The activity of such drugs depends on the chemical structure of the complexes, with changes in the ligands resulting in changes in their antitumour activity and toxicity. Assessments of the biological and toxicological effects of recently synthesized complexes must include distribution studies of platinum in the body. It is demonstrated that instrumental neutron activation analysis can be used for these studies because of its accuracy, precision and the low detection limit for platinum (approximately equal to 2 ng), when a standardized method is used. The time-dependent retention of platinum was determined in blood, liver, kidneys and cells of ascitic Walker 256 carcinosarcoma in tumour-bearing rats and controls after the administration of the cis-Pt(Gly-Gly-0Et) 2 Cl 2 complex. Two series of experiments, one with the therapeutic amount of the drug (80 mg/kg body weight) and one low-dose experiment with 1/100 of this amount, were carried out. The results of both experiments are discussed with regard to changes in the platinum concentration with time (0-48 h) in the different samples. From the data a selective uptake of the drug by the tumour cells, causing their destruction, is deduced. Because this drug has shown excellent antitumour activity, this observed selectivity suggests promise for its application in cancer chemotherapy, although platinum retention is still found in the kidneys, which might cause renal tubular damage. This latter aspect requires further clinical research to evaluate fully its effects. (author)

Structure-activity relationships of carbon-supported platinum-bismuth and platinum-antimony oxidation catalysts

CSIR Research Space (South Africa)

Maphoru, MV

2017-04-01

Full Text Available Compositional and morphological studies on supported platinum are important for the improvement and expanded use of catalysts for oxidative coupling reactions. Nanocomposites consisting of 5% Pt supported on activated carbon and promoted with 5% Bi...

Preparation of Carbon-Platinum-Ceria and Carbon-Platinum-Cerium catalysts and its application in Polymer Electrolyte Fuel Cell: Hydrogen, Methanol, and Ethanol

Science.gov (United States)

Guzman Blas, Rolando Pedro

This thesis is focused on fuel cells using hydrogen, methanol and ethanol as fuel. Also, in the method of preparation of catalytic material for the anode: Supercritical Fluid Deposition (SFD) and impregnation method using ethylenediaminetetraacetic acid (EDTA) as a chelating agent. The first part of the thesis describes the general knowledge about Hydrogen Polymer Exchange Membrane Fuel Cell (HPEMFC),Direct Methanol Fuel Cell (DMFC) and Direct Ethanol Fuel Cell (DEFC), as well as the properties of Cerium and CeO2 (Ceria). The second part of the thesis describes the preparation of catalytic material by Supercritical Fluid Deposition (SFD). SFD was utilized to deposit Pt and ceria simultaneously onto gas diffusion layers. The Pt-ceria catalyst deposited by SFD exhibited higher methanol oxidation activity compared to the platinum catalyst alone. The linear sweep traces of the cathode made for the methanol cross over study indicate that Pt-Ceria/C as the anode catalyst, due to its better activity for methanol, improves the fuel utilization, minimizing the methanol permeation from anode to cathode compartment. The third and fourth parts of the thesis describe the preparation of material catalytic material Carbon-Platinum-Cerium by a simple and cheap impregnation method using EDTA as a chelating agent to form a complex with cerium (III). This preparation method allows the mass production of the material catalysts without additional significant cost. Fuel cell polarization and power curves experiments showed that the Carbon-Platinum-Cerium anode materials exhibited better catalytic activity than the only Vulcan-Pt catalysts for DMFC, DEFC and HPEMFC. In the case of Vulcan-20%Pt-5%w Cerium, this material exhibits better catalytic activity than the Vulcan-20%Pt in DMFC. In the case of Vulcan-40% Pt-doped Cerium, this material exhibits better catalytic activity than the Vulcan-40% Pt in DMFC, DEFC and HPEMFC. Finally, I propose a theory that explains the reason why the

PGE2 suppresses intestinal T cell function in thermal injury: a cause of enhanced bacterial translocation.

Science.gov (United States)

Choudhry, M A; Fazal, N; Namak, S Y; Haque, F; Ravindranath, T; Sayeed, M M

2001-09-01

Increased gut bacterial translocation in burn and trauma patients has been demonstrated in a number of previous studies, however, the mechanism for such an increased gut bacterial translocation in injured patients remains poorly understood. Utilizing a rat model of burn injury, in the present study we examined the role of intestinal immune defense by analyzing the T cell functions. We investigated if intestinal T cells dysfunction contributes to bacterial translocation after burn injury. Also our study determined if burn-mediated alterations in intestinal T cell functions are related to enhanced release of PGE2. Finally, we examined whether or not burn-related alterations in intestinal T cell function are due to inappropriate activation of signaling molecule P59fyn, which is required for T cell activation and proliferation. The results presented here showed an increase in gut bacterial accumulation in mesenteric lymph nodes after thermal injury. This was accompanied by a decrease in the intestinal T cell proliferative responses. Furthermore, the treatments of burn-injured animals with PGE2 synthesis blocker (indomethacin or NS398) prevented both the decrease in intestinal T cell proliferation and enhanced bacterial translocation. Finally, our data suggested that the inhibition of intestinal T cell proliferation could result via PGE2-mediated down-regulation of the T cell activation-signaling molecule P59fyn. These findings support a role of T cell-mediated immune defense against bacterial translocation in burn injury.

Medical and health-related trace element analysis by TXRF

International Nuclear Information System (INIS)

Greaves, E.D.

2000-01-01

The advantages offered with TXRF analysis by direct irradiation with monochromatic X-rays of tissue homogenates and body fluids make the technique appropriate for a number of medical and health related applications. The ability to detect low levels of toxic heavy elements is being used as an aid in accidental poisoning diagnosis and treatment, in treatment-induced toxicity control and as an accessory in medical and health research. Thus lead-in-whole-blood analysis is used in confirmation of diagnosis of victims of poisoning, or monitoring the evolution and efficiency of the clinical treatment. Measurement and control of plasma platinum levels of cancer patients undergoing chemotherapy with Pt-containing drugs includes: establishment of the drug level-tumor remission response, measurement of Pt plasma level curves and establishment of optimum dosage to minimize the nephrotoxicity of platinum, and bioequivalence comparisons of different commercially available platinum containing anticancer drugs. Analysis as an aid in clinical research applications includes: trace element determination of amniotic fluid in fetus malformation studies; analysis of brain specimens and cerebrospinal fluid in diagnosis of central nervous system disorders; the influence of trace elements in cataract genesis and the influence of heavy elements in semen quality in human reproduction studies. Human body samples require the use of monochromatized beams of x-rays in order to derive the special advantage of its use: i) The reduction in the spectrum background allowing direct irradiation of organic matter specimens. Hence human tissue and body fluids are prepared by simple procedures involving dilution, homogenization and standard addition avoiding the need for specimen digestion. This results in faster, cheaper methods that decrease sample contamination problems. ii) The presence of a large Compton scattered signal in the spectrum and its use as an internal standard reference allows further

Atomically flat platinum films grown on synthetic mica

Science.gov (United States)

Tanaka, Hiroyuki; Taniguchi, Masateru

2018-04-01

Atomically flat platinum thin films were heteroepitaxially grown on synthetic fluorophlogopite mica [KMg3(AlSi3O10)F2] by van der Waals epitaxy. Platinum films deposited on a fluorophlogopite mica substrate by inductively coupled plasma-assisted sputtering with oxygen introduction on a synthetic mica substrate resulted in the growth of twin single-crystalline epitaxial Pt(111) films.

Major, trace and platinum group element (PGE) geochemistry of Archean Iron Ore Group and Proterozoic Malangtoli metavolcanic rocks of Singhbhum Craton, Eastern India: Inferences on mantle melting and sulphur saturation history

Digital Repository Service at National Institute of Oceanography (India)

Singh, M.R.; Manikyamba, C.; Ray, J.; Ganguly, S.; Santosh, M.; Saha, A.; Rambabu, S.; Sawant, S.S.

.86 0.90 0.84 3.93 0.87 0.86 0.86 0.85 0.91 Y 26.1 26.4 29.7 25.8 26.8 26.6 26.3 29.0 26.2 29.3 La 20.17 20.32 21.84 19.45 20.18 20.06 20.17 20.93 20.10 21.38 Ce 42.56 43.25 45.28 41.55 43.10 42.44 42.95 42.48 42.59 44.13 Pr 3.79 3.88 4.24 3.78 3.86 3....82 3.86 4.05 3.84 4.11 Nd 19.56 19.92 21.82 19.38 20.18 19.88 19.84 21.25 19.82 21.16 Sm 4.23 4.39 4.76 4.27 4.44 4.41 4.42 4.66 4.34 4.57 Eu 1.43 1.17 1.25 1.08 1.27 1.21 1.17 1.30 1.23 1.21 Gd 5.47 5.66 6.02 5.34 5.56 5.46 5.47 5.82 5.59 5.85 Tb 0...

On the enzymatic formation of platinum nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Govender, Y.; Riddin, T. L. [Rhodes University, Department of Biochemistry, Microbiology and Biotechnology (South Africa); Gericke, M. [MINTEK (South Africa); Whiteley, C. G., E-mail: C.Whiteley@ru.ac.z [Rhodes University, Department of Biochemistry, Microbiology and Biotechnology (South Africa)

2010-01-15

A dimeric hydrogenase enzyme (44.5 and 39.4 kDa sub units) was isolated in a 39.5% yield from the fungus Fusarium oxysporum and purified 4.64-fold by ion exchange chromatography on Sephacryl S-200. Characterisation of the enzyme afforded pH and temperature optima of 7.5 and 38 {sup o}C, respectively, a half-life stability of 36 min and a V{sub max} and K{sub m} of 3.57 nmol min{sup -1} mL{sup -1} and 2.25 mM, respectively. This enzyme was inhibited (non-competitively) by hydrogen hexachloroplatinic acid (H{sub 2}PtCl{sub 6}) at 1 or 2 mM with a K{sub i} value of 118 {mu}M. Incubation of the platinum salt with the pure enzyme under an atmosphere of hydrogen and optimum enzyme conditions (pH 7.5, 38 {sup o}C) afforded <10% bioreduction after 8 h while at conditions suitable for platinum nanoparticle formation (pH 9, 65 {sup o}C) over 90% reduction took place after the same length of time. Cell-free extract from the fungal isolates produced nearly 90% bioreduction of the platinum salt under both pH and temperature conditions. The bioreduction of the platinum salt by a hydrogenase enzyme takes place by a passive process and not an active one as previously understood.

Isoliquiritigenin, a flavonoid from licorice, blocks M2 macrophage polarization in colitis-associated tumorigenesis through downregulating PGE{sub 2} and IL-6

Energy Technology Data Exchange (ETDEWEB)

Zhao, Haixia [Department of Pharmacology, School of Medicine, Wuhan University, Wuhan 430071 (China); Zhang, Xinhua [Department of Liver, Biliary And Pancreatic Tumors, Hubei Cancer Hospital, Wuhan 430079 (China); Chen, Xuewei; Li, Ying; Ke, Zunqiong [Department of Pharmacology, School of Medicine, Wuhan University, Wuhan 430071 (China); Tang, Tian [Department of Oncology, Renmin Hospital of Wuhan University, Wuhan 430060 (China); Chai, Hongyan [Center for Gene Diagnosis, Zhongnan Hospital, Wuhan University, Wuhan 430071 (China); Guo, Austin M. [Department of Pharmacology, School of Medicine, Wuhan University, Wuhan 430071 (China); Department of Pharmacology, New York Medical College, Valhalla, NY 10595 (United States); Chen, Honglei, E-mail: hl-chen@whu.edu.cn [Department of Pathology and Pathophysiology, School of Medicine, Wuhan University, Wuhan 430071 (China); Yang, Jing, E-mail: yangjingliu2013@163.com [Department of Pharmacology, School of Medicine, Wuhan University, Wuhan 430071 (China)

2014-09-15

M2 macrophage polarization is implicated in colorectal cancer development. Isoliquiritigenin (ISL), a flavonoid from licorice, has been reported to prevent azoxymethane (AOM) induced colon carcinogenesis in animal models. Here, in a mouse model of colitis-associated tumorigenesis induced by AOM/dextran sodium sulfate (DSS), we investigated the chemopreventive effects of ISL and its mechanisms of action. Mice were treated with AOM/DSS and randomized to receive either vehicle or ISL (3, 15 and 75 mg/kg). Tumor load, histology, immunohistochemistry, and gene and protein expressions were determined. Intragastric administration of ISL for 12 weeks significantly decreased colon cancer incidence, multiplicity and tumor size by 60%, 55.4% and 42.6%, respectively. Moreover, ISL inhibited M2 macrophage polarization. Such changes were accompanied by downregulation of PGE{sub 2} and IL-6 signaling. Importantly, depletion of macrophages by clodronate (Clod) or zoledronic acid (ZA) reversed the effects of ISL. In parallel, in vitro studies also demonstrated that ISL limited the M2 polarization of RAW264.7 cells and mouse peritoneal macrophages with concomitant inactivation of PGE{sub 2}/PPARδ and IL-6/STAT3 signaling. Conversely, exogenous addition of PGE{sub 2} or IL-6, or overexpression of constitutively active STAT3 reversed ISL-mediated inhibition of M2 macrophage polarization. In summary, dietary flavonoid ISL effectively inhibits colitis-associated tumorigenesis through hampering M2 macrophage polarization mediated by the interplay between PGE{sub 2} and IL-6. Thus, inhibition of M2 macrophage polarization is likely to represent a promising strategy for chemoprevention of colorectal cancer. - Highlights: • Isoliquiritigenin (ISL) prevents colitis-associated tumorigenesis. • ISL inhibits M2 macrophage polarization in vivo and in vitro. • ISL inhibits PGE{sub 2} and IL-6 signaling in colitis-associated tumorigenesis. • ISL may be an attractive candidate agent for

Investigation of a combined platinum and electron lifetime control treatment for silicon

International Nuclear Information System (INIS)

Jia, Yunpeng; Cui, Zhihang; Yang, Fei; Zhao, Bao; Zou, Shikai; Liang, Yongsheng

2017-01-01

In silicon, the effect of Combined Lifetime Treatment (CLT) involving platinum diffusion and subsequent electron irradiation is different from the separate treatments of platinum diffusion and electron irradiation, even the treatment of electron irradiation followed by platinum diffusion. In this paper, we investigated the experimental behavior of different kinds of lifetime treated samples. We found that the reverse leakage current (I rr ) increases with the increasing platinum diffusion temperature or electron irradiation dose in the separate treatments. Conversely, I rr of the CLT samples decreased with rising platinum diffusion temperature at the same dose of subsequent electron irradiation. By deep-level transient spectroscopy (DLTS), a new energy level E7 (Ec −0.376 eV) was found in our CLT samples. The new level E7 suppresses the dominance of the deeper level E8 (Ec −0.476 eV), which is caused by electron irradiation directly and results in I rr ’s increase. The formation of the level E7 comes from the complex defect-combined effect between platinum atoms and silicon vacancies, and it affects device’s characteristics finally. These research will be helpful to the development of platinum-diffused devices used in intense electron irradiation environments.

Investigation of a combined platinum and electron lifetime control treatment for silicon

Energy Technology Data Exchange (ETDEWEB)

Jia, Yunpeng [College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing 100124 (China); Cui, Zhihang, E-mail: czhczh321321@126.com [College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing 100124 (China); Yang, Fei [State Grid Smart Electrical Engineering, Beijing 100192 (China); Zhao, Bao; Zou, Shikai; Liang, Yongsheng [College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing 100124 (China)

2017-02-01

In silicon, the effect of Combined Lifetime Treatment (CLT) involving platinum diffusion and subsequent electron irradiation is different from the separate treatments of platinum diffusion and electron irradiation, even the treatment of electron irradiation followed by platinum diffusion. In this paper, we investigated the experimental behavior of different kinds of lifetime treated samples. We found that the reverse leakage current (I{sub rr}) increases with the increasing platinum diffusion temperature or electron irradiation dose in the separate treatments. Conversely, I{sub rr} of the CLT samples decreased with rising platinum diffusion temperature at the same dose of subsequent electron irradiation. By deep-level transient spectroscopy (DLTS), a new energy level E7 (Ec −0.376 eV) was found in our CLT samples. The new level E7 suppresses the dominance of the deeper level E8 (Ec −0.476 eV), which is caused by electron irradiation directly and results in I{sub rr}’s increase. The formation of the level E7 comes from the complex defect-combined effect between platinum atoms and silicon vacancies, and it affects device’s characteristics finally. These research will be helpful to the development of platinum-diffused devices used in intense electron irradiation environments.

Relaxant effect of ghrelin on guinea pig isolated tracheal smooth muscle: role of epithelial NO and PGE2.

Science.gov (United States)

Al-Ayed, Mohammed Saeed Zayed

2018-06-01

This study aimed at investigating the potential ghrelin relaxing effect on guinea pig isolated tracheal smooth muscle (TSM). Using an in vitro experimental approach, the physiological role of the airway epithelium on smooth muscle relaxation has been investigated by analyzing the dose-response curves for carbachol- or histamine-induced contractions on epithelium intact versus denuded tracheal tissue. The relaxant effect of ghrelin (5-200 μmol/L) then investigated on carbachol-contracted, non-sensitized, and ovalbumin (OVA)-sensitized guinea pig TSM with an intact or denuded epithelium. The isolated TSMs from identical guinea pigs were incubated in Krebs solution aerated with 95% O 2 and 5% CO 2 through an automated tissue organ bath system (n = 6 for each group). The ghrelin relaxation mechanism was assessed by adding L-NAME, indomethacin, and YIL-781 for GHS-R1 into the tissue chamber. The spasmogens carbachol and histamine have shown a significantly higher contracting effect on epithelium-denuded than in epithelium-intact TSM confirmed by the significantly higher mean pEC50 of both agonists on the epithelium-denuded trachea (p < 0.05). Ghrelin has shown a concentration-dependent relaxing effect on carbachol-contracted TSM (r = 0.96, p = 0.00). The effect was more evident in the intact non-sensitized than in epithelium-denuded or OVA-sensitized groups (p < 0.05). Preincubation with nitric oxide (NO) and prostaglandin E 2 (PGE 2 ) inhibitors has significantly reduced the ghrelin-induced relaxation on epithelium-intact TSM suggesting an epithelium-dependant mechanism. However, GHS-R1a antagonist has also succeeded to reduce ghrelin relaxant effect, which needs further clarification. Ghrelin proved to have a potential TSM relaxant effect possibly through epithelium-dependant mechanisms involving NO and PGE 2 .

Some Chemical Group Separations of Radioactive Trace Elements

Energy Technology Data Exchange (ETDEWEB)

Samsahl, K

1962-06-15

As a pretreatment for gamma spectrometric analysis methods have been developed for the chemical separation of traces of P, Sc, Ge, As, Se, Br, Zr, Nb, Ru, Ag, Cd, Sn, Sb, I, Hf, Ta, Re, Os, Au and Hg into 9 different groups. By combining the present methods with already existing chemical group separation methods for traces of Na, K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Rb, Sr, Mo, In, Fe, Cs, Ba, L.a, the rare earths, W and Ir, a complete separation scheme comprising 15 groups of elements has been worked out. The chemical 15-group separation method has been advantageously used in gamma spectrometric routine analysis of biological materials.

Some Chemical Group Separations of Radioactive Trace Elements

International Nuclear Information System (INIS)

Samsahl, K.

1962-06-01

As a pretreatment for gamma spectrometric analysis methods have been developed for the chemical separation of traces of P, Sc, Ge, As, Se, Br, Zr, Nb, Ru, Ag, Cd, Sn, Sb, I, Hf, Ta, Re, Os, Au and Hg into 9 different groups. By combining the present methods with already existing chemical group separation methods for traces of Na, K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Rb, Sr, Mo, In, Fe, Cs, Ba, L.a, the rare earths, W and Ir, a complete separation scheme comprising 15 groups of elements has been worked out. The chemical 15-group separation method has been advantageously used in gamma spectrometric routine analysis of biological materials

The probability that a pair of group elements is autoconjugate

Indian Academy of Sciences (India)

Let and ℎ be arbitrary elements of a given finite group . Then and ℎ are said to be autoconjugate if there exists some automorphism of such that ℎ = . In this article, we construct some sharp bounds for the probability that two random elements of are autoconjugate, denoted by P a ( G ) . It is also shown that P ...

DMPD: Pivotal role of PGE2 and IL-10 in the cross-regulation of dendritic cell-derivedinflammatory mediators. [Dynamic Macrophage Pathway CSML Database

Lifescience Database Archive (English)

Full Text Available l) (.csml) Show Pivotal role of PGE2 and IL-10 in the cross-regulation of dendritic cell-derivedinflammatory mediator...egulation of dendritic cell-derivedinflammatory mediators. Authors Harizi H, Gualde N. Publication Cell Mol ...16978535 Pivotal role of PGE2 and IL-10 in the cross-regulation of dendritic cell-derivedinflammatory mediat...ors. Harizi H, Gualde N. Cell Mol Immunol. 2006 Aug;3(4):271-7. (.png) (.svg) (.htm

Platinum catalyst formed on carbon nanotube by the in-liquid plasma method for fuel cell

Energy Technology Data Exchange (ETDEWEB)

Show, Yoshiyuki; Hirai, Akira; Almowarai, Anas; Ueno, Yutaro

2015-12-01

In-liquid plasma was generated in the carbon nanotube (CNT) dispersion fluid using platinum electrodes. The generated plasma spattered the surface of the platinum electrodes and dispersed platinum particles into the CNT dispersion. Therefore, the platinum nanoparticles were successfully formed on the CNT surface in the dispersion. The platinum nanoparticles were applied to the proton exchange membrane fuel cell (PEMFC) as a catalyst. The electrical power of 108 mW/cm{sup 2} was observed from the fuel cell which was assembled with the platinum catalyst formed on the CNT by the in-liquid plasma method. - Highlights: • The platinum catalyst was successfully formed on the CNT surface in the dispersion by the in-liquid plasma method. • The electrical power of 108 mW/cm{sup 2} was observed from the fuel cell which was assembled with the platinum catalyst formed on the CNT by the in-liquid plasma method.

Efficient organic light-emitting devices with platinum-complex emissive layer

KAUST Repository

Yang, Xiaohui

2011-01-18

We report efficient organic light-emitting devices having a platinum-complex emissive layer with the peak external quantum efficiency of 17.5% and power efficiency of 45 lm W−1. Variation in the device performance with platinum-complex layer thickness can be attributed to the interplay between carrier recombination and intermolecular interactions in the layer. Efficient white devices using double platinum-complex layers show the external quantum efficiency of 10%, the Commission Internationale d’Énclairage coordinates of (0.42, 0.41), and color rendering index of 84 at 1000 cd m−2.

Efficient organic light-emitting devices with platinum-complex emissive layer

KAUST Repository

Yang, Xiaohui; Wu, Fang-Iy; Haverinen, Hanna; Li, Jian; Cheng, Chien-Hong; Jabbour, Ghassan E.

2011-01-01

We report efficient organic light-emitting devices having a platinum-complex emissive layer with the peak external quantum efficiency of 17.5% and power efficiency of 45 lm W−1. Variation in the device performance with platinum-complex layer thickness can be attributed to the interplay between carrier recombination and intermolecular interactions in the layer. Efficient white devices using double platinum-complex layers show the external quantum efficiency of 10%, the Commission Internationale d’Énclairage coordinates of (0.42, 0.41), and color rendering index of 84 at 1000 cd m−2.

Enzymatic recovery of platinum (IV) from industrial wastewater using ...

African Journals Online (AJOL)

highest hydrogen-dependent platinum (IV) reducing activity in the presence of hydrogenase and its physiological electron carrier, cytochrome c3. When the purified hydrogenase enzyme (with and without cytochrome c3) was used with the industrial effluent, containing 7.9 mg.l-1 platinum, only 10 – 15% recovery was noted ...

Method to determine trace elements in water samples by neutron activation analysis

International Nuclear Information System (INIS)

Kueppers, G.; Erdtmann, G.

1981-05-01

For the determination of trace elements in water by neutron activation analysis irradiation porcedures and chemical separation procedures have been developed. Irradiation in melted quarz glass ampoules in the presence of a platinum wire (for recombination of the oxyhydrogen gas produced by radiolysis) proved successfull with different variants of the irradiation methods, as long irradiation periods without pressure build-up could be achieved. Possible falsifications of the analysis results were investigated in detail (losses by absorption on vessel walls etc.). The irradiated samples can be measured directly with a gamma ray spectrometer and from the radionuclides found the trace element contents may be calculated. More sensitive determinations are possible if the radionuclides are chemically separated. Procedures for removing the matrix activities, for the separation of the radionuclides in groups of elements and for the isolation of single elements have been developed. For especially sensitive determination of some elements selective separation procedures for antimony, cadmium, selenium, mercury and uranium have been developed. The analytical procedures described have been applied to trace element determinations in river water, glacier ice and water solutions from technical processes. (orig./RB) [de

Parallel and Serial Grouping of Image Elements in Visual Perception

Science.gov (United States)

Houtkamp, Roos; Roelfsema, Pieter R.

2010-01-01

The visual system groups image elements that belong to an object and segregates them from other objects and the background. Important cues for this grouping process are the Gestalt criteria, and most theories propose that these are applied in parallel across the visual scene. Here, we find that Gestalt grouping can indeed occur in parallel in some…

Research sources of ionizing radiation based on transplutonium elements

Science.gov (United States)

Radchenko, V. M.; Ryabinin, M. A.

2010-03-01

Scientific and technical demand stimulates an extension of the practical implementation field of TPE, requirements to their ecological safety calling for the development of such materials which could be most resistant to the environment and most suitable for the production of a wide range of sources different in their application and design. Such materials can involve pure metals of transplutonium elements and their alloys with metals of platinum group as well as their chemically stable compounds (such as silicides, carbides etc.) At SSC RIAR production processes of sources of different type and application have been implemented. Examples of the most recent developments of the sources are presented below. Presented is the analysis of the current state of issues related to designing, production and application of radionuclide research sources based on transplutonium elements. Examples of the development of the most up-to-date sources of alpha-, gamma- and neutron radiation and also fission ones are considered.

Efecto del ácido linoléico sobre la producción de las prostaglandinas PGF2α y PGE2 en células endometriales

Directory of Open Access Journals (Sweden)

Yasser Lenis S.

2013-08-01

Full Text Available Objetivo. Evaluar el efecto in vitro del ácido linoléico sobre la producción de PGF2α y PGE2 en células endometriales epiteliales bovinas (CEEP. Materiales y métodos. Se cultivaron CEEP aisladas de tejido uterino y se suplementaron con AL a diferentes concentraciones (1 μM, 10 μM, 100 μM, oxitocina (OT (0.1 μM e interferón trofoectodérmico bovino (bINT-τ (50 ng/ml. Se cuantificó la PGF2α y PGE2 a distintos tiempos (12, 24 y 36h. En el control, la PGF2α en el sobrenadante aumentó en el tiempo de cultivo y fue 1.2 veces mayor que la producción de PGE2. Resultados. El ácido linoléico disminuyó la concentración de PGF2α (p0.05 la producción de PGE2. El efecto conjunto de AL y OT sobre la producción de PGF2α difirió para cada uno de los tiempos; el ácido linoléico inhibió parcialmente el efecto estimulante de la OT sobre la producción de PGE2, el efecto conjunto del AL y el bINT-τ aumentó (p<0.05 esta inhibición hasta la hora 24. Conclusiones. El ácido linoléico afecta negativamente la concentración de PGF2α en el sobrenadante a través del tiempo. Respecto a la PGE2 se concluye que el ácido linoléico por sí solo no afecta la concentración en el sobrenadante.

BPA/PGE transmission support project: Final environmental assessment

International Nuclear Information System (INIS)

1996-12-01

This Mitigation Action Plan describes the mitigation measures identified in the BPA/PGE Transmission Support Project Environmental Assessment. These measures commit to actions that will reduce the environmental impacts that could occur by constructing, operating and maintaining the transmission line and related facilities. They have been developed in coordination with environmental specialists, design and construction engineers and maintenance personnel. The measures will be written into the construction specifications for the project, which is expected to be constructed by contract personnel. Unless noted in the plan, the construction inspector or the line foreman would be responsible for carrying out the mitigation; environmental staff would also monitor the area for mitigation effectiveness. The right-of-way would be cleared in 1997 or 1998, and construction would begin in the spring of 1998 and be completed later that fall

Structural property of platinum mononitride

International Nuclear Information System (INIS)

Yu, L.H.; Yao, K.L.; Liu, Z.L.; Zhang, Y.S.

2007-01-01

The structural stability and pressure-induced structural phase transition of platinum mononitride (PtN), as well as its electronic structure, were studied using the full potential augmented plane wave plus local orbitals method with the generalized gradient approximation (GGA) exchange-correlation functional. The total energy calculations show that the optimized wurtzite structure is most stable energetically among four structures: zinc blende, rocksalt, CsCl and wurtzite, which reveals the platinum mononitride PtN perhaps crystallizes in the wurtzite structure; the pressure of phase transition from wurtzite to rocksalt is predicted to be 41.4 GPa.The calculated bulk modulus of the wurtzite structure is 99.41 GPa, which is smaller than that of the other three structures and face-centered cubic Pt. The band structure calculations show wurtzite PtN is metallic

Determination of iridium at low levels (sub ng g-1) in geological materials by neutron activation analysis

International Nuclear Information System (INIS)

Morcelli, Claudia Petronilho Ribeiro

1999-01-01

The analysis of the platinum group elements (PGE: Ru, Rh, Pd, Os, Ir and Pt) in geological materials is difficult, due to the low concentrations of these elements (ng g -1 or sub ng g -1 ) and their heterogeneous distribution in many geological matrices. The determination of PGE has attracted great interest due not only to the increasing utilization of these elements in modern industry, but also to the information that these elements can provide on mantle processes. The determination of very low amounts of iridium is particularly important on account of some anomalous concentrations of iridium in sedimentary rock samples, related to the impact of an extraterrestrial object responsible for extinctions at the Cretaceous-Tertiary (K-T) boundary. In the present paper, a radiochemical neutron activation method for the determination of iridium in geological materials is presented. The procedure consisted of thermal neutron irradiation of about 500 mg of the sample, followed by sintering with sodium peroxide, precipitation with tellurium and high resolution gamma-ray spectrometry with a hyper-pure Ge detector. The accuracy and precision of the procedure were evaluated by analysis of the certified reference material SARM-7 (South Africa Bureau of Standards) and W-1 (USGS). The detection limit for the analytical conditions employed was 0.004 ng g -1 . The procedure was applied to the reference materials TDB-1 and WGB-1 (CANMET), which present provisional values for Ir, and to the reference materials GXR-3, GXR-5 and GXR- 6 (USGS), which do not present information values for Ir. This work is a contribution to Ir values in these reference materials. As an example of application of the method to real samples, the developed procedure was employed in the determination of iridium in basalts from Parana basin, collected in Bom Guara do Sul, Santa Catarina, provided by the Geosciences Institute of the University of Campinas. (author)

Quantum Chemical Calculations and Molecular Docking Studies of Some NSAID Drugs (Aceclofenac, Salicylic Acid, and Piroxicam as 1PGE Inhibitors

Directory of Open Access Journals (Sweden)

S. Suresh

2016-01-01

Full Text Available The molecular structure of the three compounds Aceclofenac (I, Salicylic Acid (II, and Piroxicam (III has been determined using Gaussian 03W program with B3LYP method using 6-311++G (d,p basis set calculations. The molecular structures were fully optimized with atomic numbering scheme adopted in the study. To understand the mode of binding and molecular interaction, the docking studies of compounds Aceclofenac (I, Salicylic Acid (II, and Piroxicam (III have been carried out with prostaglandin H2 synthase-1 (1PGE as target using induced fit docking. The molecular docking results show that the interactions and energy for Aceclofenac, Salicylic Acid, and Piroxicam show the best results when docked with prostaglandin H2 synthase-1 (1PGE. The hydrogen bonding interactions of compound I (Aceclofenac are prominent with Arginine moiety, those of compound II (Salicylic Acid are prominent with Tyrosine and Serine moieties, and compound III (Piroxicam shows such interaction with Tyrosine and Arginine moieties. These interactions of prostaglandin H2 synthase-1 (1PGE with substrates are responsible for governing COX-1 inhibitor potency which in turn is a direct measure of the potency of the drug.

Tripodal osmium polypyridyl complexes for self-assembly on platinum nanoparticles

NARCIS (Netherlands)

Contreras-Carballada, P.; Edafe, F.; Tichelaar, F.D.; Belser, P.; De Cola, L.; Williams, R.M.

2011-01-01

The combination of platinum nanoparticles with a tripodal osmium complex that anchors to the metal surface leads, under visible light irradiation, to the formation of solvated electrons. The formation kinetics is limited by the detachment of the electron from the platinum surface into the solution,

The 5th Symposium on Post-Transcriptional Regulation of Plant Gene Expression (PTRoPGE)

Energy Technology Data Exchange (ETDEWEB)

Karen S. Browning; Marie Petrocek; Bonnie Bartel

2006-06-01

The 5th Symposium on Post-Transcriptional Regulation of Plant Gene Expression (PTRoPGE) will be held June 8-12, 2005 at the University of Texas at Austin. Exciting new and ongoing discoveries show significant regulation of gene expression occurs after transcription. These post-transcriptional control events in plants range from subtle regulation of transcribed genes and phosphorylation, to the processes of gene regulation through small RNAs. This meeting will focus on the regulatory role of RNA, from transcription, through translation and finally degradation. The cross-disciplinary design of this meeting is necessary to encourage interactions between researchers that have a common interest in post-transcriptional gene expression in plants. By bringing together a diverse group of plant molecular biologist and biochemists at all careers stages from across the world, this meeting will bring about more rapid progress in understanding how plant genomes work and how genes are finely regulated by post-transcriptional processes to ultimately regulate cells.

Parallel and serial grouping of image elements in visual perception

NARCIS (Netherlands)

Houtkamp, R.; Roelfsema, P.R.

2010-01-01

The visual system groups image elements that belong to an object and segregates them from other objects and the background. Important cues for this grouping process are the Gestalt criteria, and most theories propose that these are applied in parallel across the visual scene. Here, we find that

Platinum single crystal electrodes for the electrocatalysis of methane oxidation

Directory of Open Access Journals (Sweden)

Mayara Munaretto

2011-03-01

Full Text Available The main objective of this paper is to characterize the voltammetric profiles of platinum single crystals of low Miller indexes Pt(100 and Pt(110 and study their catalytic activities on the oxidation of methane. In this way, it was developed a metallic surface modified by presence of other metal oxide, which presents catalytic activity for this reaction. It is well known that the electrooxidation of methane (CH4 leads mainly to the formation of CO2 and H2O, however, the oxidation can also lead to the formation of CO, a reaction intermediate that has strong interaction with metal surfaces, such as platinum. This molecule tends to accumulate on the platinum surface and to passive it, due to the self-poisoning, decreasing its catalytic activity. Therefore, the main aim of this work was the development of a platinum electrode modified by deposition of titanium oxide, which presented electrocatalytic properties for the oxidation of methane.

Universal dependence of hydrogen oxidation and evolution reaction activity of platinum-group metals on pH and hydrogen binding energy.

Science.gov (United States)

Zheng, Jie; Sheng, Wenchao; Zhuang, Zhongbin; Xu, Bingjun; Yan, Yushan

2016-03-01

Understanding how pH affects the activity of hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) is key to developing active, stable, and affordable HOR/HER catalysts for hydroxide exchange membrane fuel cells and electrolyzers. A common linear correlation between hydrogen binding energy (HBE) and pH is observed for four supported platinum-group metal catalysts (Pt/C, Ir/C, Pd/C, and Rh/C) over a broad pH range (0 to 13), suggesting that the pH dependence of HBE is metal-independent. A universal correlation between exchange current density and HBE is also observed on the four metals, indicating that they may share the same elementary steps and rate-determining steps and that the HBE is the dominant descriptor for HOR/HER activities. The onset potential of CO stripping on the four metals decreases with pH, indicating a stronger OH adsorption, which provides evidence against the promoting effect of adsorbed OH on HOR/HER.

LDRD final report on synthesis of shape-and size-controlled platinum and platinum alloy nanostructures on carbon with improved durability.

Energy Technology Data Exchange (ETDEWEB)

Shelnutt, John Allen; Garcia, Robert M.; Song, Yujiang; Moreno, Andres M.; Stanis, Ronald J.

2008-10-01

This project is aimed to gain added durability by supporting ripening-resistant dendritic platinum and/or platinum-based alloy nanostructures on carbon. We have developed a new synthetic approach suitable for directly supporting dendritic nanostructures on VXC-72 carbon black (CB), single-walled carbon nanotubes (SWCNTs), and multi-walled carbon nanotubes (MWCNTs). The key of the synthesis is to creating a unique supporting/confining reaction environment by incorporating carbon within lipid bilayer relying on a hydrophobic-hydrophobic interaction. In order to realize size uniformity control over the supported dendritic nanostructures, a fast photocatalytic seeding method based on tin(IV) porphyrins (SnP) developed at Sandia was applied to the synthesis by using SnP-containing liposomes under tungsten light irradiation. For concept approval, one created dendritic platinum nanostructure supported on CB was fabricated into membrane electrode assemblies (MEAs) for durability examination via potential cycling. It appears that carbon supporting is essentially beneficial to an enhanced durability according to our preliminary results.

Invited: Tailoring Platinum Group Metals Towards Optimal Activity for Oxygen Electroreduction to H2o and H2O2: From Extended Surfaces to Nanoparticles

DEFF Research Database (Denmark)

Stephens, Ifan

2014-01-01

). The figure shows transmission electron miscroscopy images of 9 nm diameter PtxY nanoparticles, based on high angle annular dark field –scanning transmission electron microscopy (left) and Y, Pt and combined Pt+Y X-ray energy dispersive X-ray spectroscopy elemental maps. (a) as-prepared catalyst and (b) after......The slow kinetics of the 4-electron reduction of oxygen to H2O imposes a bottleneck against the widespread uptake of low temperature fuel cells in automotive vehicles. High loadings of platinum are required to drive the reaction; the limited supply of this precious metal limits the extent to which...... fuel cell technology could be scaled up.(1) The most widely used strategy towards decreasing the Pt loading is to alloy Pt with other late transition metals, in particular Ni or Co. (2-5) However, when tested in a fuel cell, these alloys are often susceptible towards degradation via dealloying.(6, 7...

Platinum-Bismuth Bimetallic Catalysts: Synthesis, Characterization and Applications

OpenAIRE

Saucedo, Jose A, Jr; Xiao, Yang; Varma, Arvind

2015-01-01

Bimetallic catalysts have been explored and shown to exhibit unique characteristics which are not present in monometallic catalysts. Platinum is well known as an effective catalyst for oxidation and reduction reactions, and it can be made more effective when bismuth is introduced as a promotor. Thus, the effectiveness of the Pt-Bi catalyst was demonstrated in prior work. What is not clear, however, is the mechanism behind the catalyst function; why addition of bismuth to platinum decreases de...

Microstructural Study on Oxidation Resistance of Nonmodified and Platinum Modified Aluminide Coating

Science.gov (United States)

Zagula-Yavorska, Maryana; Sieniawski, Jan

2014-03-01

Platinum electroplating layers (3 and 7 μm thick) were deposited on the surface of the Inconel 713 LC, CMSX 4, and Inconel 625 Ni-base superalloys. Diffusion treatment at 1050°C for 2 h under argon atmosphere was performed after electroplating. Diffusion treated samples were aluminized according to the low activity CVD process at 1050°C for 8 h. The nonmodified aluminide coatings consist of NiAl phase. Platinum modification let to obtain the (Ni,Pt)Al phase in coatings. The coated samples were subjected to cyclic oxidation testing at 1100°C. It was discovered that increase of the platinum electroplating thickness from 3 to 7 μm provides the improvement of oxidation resistance of aluminide coatings. Increase of the platinum thickness causes decreases in weight change and decreases in parabolic constant during oxidation. The platinum provides the pure Al2O3 oxide formation, slow growth oxide layer, and delay the oxide spalling during heating-cooling thermal cycles.

Origin of the different behavior of some platinum decorated nanocarbons towards the electrochemical oxidation of hydrogen peroxide

International Nuclear Information System (INIS)

Malara, A.; Leonardi, S.G.; Bonavita, A.; Fazio, E.; Stelitano, S.; Neri, G.; Neri, F.; Santangelo, S.

2016-01-01

The electrochemical behavior of different platinum-decorated nanocarbons (Pt@C) towards the oxidation of hydrogen peroxide (H_2O_2) was investigated. Three different types of nanocarbons were considered: i) carbon black, ii) dahlia-like carbon nanohorns and iii) carbon nanotubes, which included both commercial (single-wall and multi-wall) and laboratory prepared (multi-wall) samples. Shape and size distribution of the platinum nanoparticles and morphology of the nanocarbons were analyzed by transmission electron microscopy. Their nanostructure was investigated by micro-Raman spectroscopy, while elemental composition of the samples and chemical bonding states were studied by X-ray photoelectron spectroscopy. Electrochemical behavior towards H_2O_2 oxidation was evaluated by means of cyclic voltammetry modifying the working screen-printed carbon electrode surface with the prepared Pt@C nanocomposites. Data obtained suggest that the size and dispersion of the Pt nanoparticles play a key role in increasing the sensitivity towards H_2O_2 detection. Thanks to the presence of smaller and more dispersed platinum particles and of a greater amount of platinum hydroxide, acting as intermediary in the H_2O_2 oxidation process, Pt@dahlia-like carbon nanohorns result to be the most promising platform for the development of H_2O_2 electrochemical sensors. - Highlights: • Different nanocarbons are decorated with Pt nanoparticles by wet impregnation method. • Pt@C-based hybrids are tested as active materials for sensing of hydrogen peroxide. • Sensor based on Pt@dahlia-like carbon nanohorns is the most performing device. • The origin of the different electrochemical behaviour is investigated. • Pt@C sensing performances are correlated with their structural and surface properties.

The development of platinum-based alloys and their thermodynamic database

Directory of Open Access Journals (Sweden)

Cornish L.A.

2002-01-01

Full Text Available A series of quaternary platinum-based alloys have been demonstrated to exhibit the same two-phase structure as Ni-based superalloys and showed good mechanical properties. The properties of ternary alloys were a good indication that the quaternary alloys, with their better microstructure, will be even better. The quaternary alloy composition has been optimised at Pt84:Al11:Ru2:Cr3 for the best microstructure and hardness. Work has begun on establishing a thermodynamic database for Pt-Al-Ru-Cr alloys, and further work will be done to enhance the mechanical and oxidation properties of the alloys by adding small amounts of other elements to the base composition of Pt84:Al11:Ru2:Cr3.

Critical Factors Controlling Pd and Pt Potential in Porphyry Cu–Au Deposits: Evidence from the Balkan Peninsula

Directory of Open Access Journals (Sweden)

Demetrios G. Eliopoulos

2014-03-01

Full Text Available Porphyry Cu–Au–Pd±Pt deposits are significant Au resources, but their Pd and Pt potential is still unknown. Elevated Pd, Pt (hundreds of ppb and Au contents are associated with typical stockwork magnetite-bornite-chalcopyrite assemblages, at the central parts of certain porphyry deposits. Unexpected high grade Cu–(Pd+Pt (up to 6 ppm mineralization with high Pd/Pt ratios at the Elatsite porphyry deposit, which is found in a spatial association with the Chelopech epithermal deposit (Bulgaria and the Skouries porphyry deposit, may have formed during late stages of an evolved hydrothermal system. Estimated Pd, Pt and Au potential for porphyry deposits is consistent with literature model calculations demonstrating the capacity of aqueous vapor and brine to scavenge sufficient quantities of Pt and Pd, and could contribute to the global platinum-group element (PGE production. Critical requirements controlling potential of porphyry deposits may be from the metals contained in magma (metasomatized asthenospheric mantle wedge as indicated by significant Cr, Co, Ni and Re contents. The Cr content may be an indicator for the mantle input.

Properties of Group Five and Group Seven transactinium elements

International Nuclear Information System (INIS)

Wilk, Philip A.

2001-01-01

The detection and positive identification of the short-lived, low cross section isotopes used in the chemical studies of the heaviest elements are usually accomplished by measuring their alpha-decay, thus the nuclear properties of the heaviest elements must be examined simultaneously with their chemical properties. The isotopes 224 Pa and 266,267 Bh have been studied extensively as an integral part of the investigation of the heaviest members of the groups five and seven of the periodic table. The half-life of 224 Pa was determined to be 855 plus/minus19 ms by measuring its alpha-decay using our rotating wheel, solid state detector system at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. Protactinium was produced by bombardment of a bismuth target. New neutron rich isotopes, 267 Bh and 266 Bh, were produced in bombardments of a 249 Bk target and their decay was observed using the rotating wheel system. The 266 Bh that was produced decays with a half-life of approximately 1 s by emission of alpha particles with an average energy of 9.25 plus/minus 0.03 MeV. 267 Bh was observed to decay with a 17 s half-life by emission of alpha-particles with an average energy of 8.83 plus/minus 0.03 MeV. The chemical behavior of hafnium, Ha (element 105) was investigated using the fast on-line continuous liquid extraction and detection system SISAK-LISSY. Hafnium was not observed in this experiment following transport and extraction. Protactinium was used as on-line test of the apparatus to determine the experimental efficiency of the entire system. Unfortunately, the amount of protactinium observed after the extraction, compared to the amount produced, was extremely small, only 2.5%. The extraction of the protactinium isotope indicated the efficiency of the apparatus was too low to observe the extraction of hafnium. The chemical behavior of oxychloride compounds of bohrium was investigated by isothermal gas adsorption chromatography in a quartz column at 180, 150

Molecules and Models The molecular structures of main group element compounds

CERN Document Server

Haaland, Arne

2008-01-01

This book provides a systematic description of the molecular structures and bonding in simple compounds of the main group elements with particular emphasis on bond distances, bond energies and coordination geometries. The description includes the structures of hydrogen, halogen and methyl derivatives of the elements in each group, some of these molecules are ionic, some polar covalent. The survey of molecules whose structures conform to well-established trends is followed byrepresentative examples of molecules that do not conform. We also describe electron donor-acceptor and hydrogen bonded co

Synthesis and Properties of Platinum Nanoparticles by Pulsed Laser Ablation in Liquid

Directory of Open Access Journals (Sweden)

Maria Isabel Mendivil Palma

2016-01-01

Full Text Available Platinum (Pt nanoparticles were synthesized by pulsed laser ablation in liquid (PLAL technique in different liquids (acetone, ethanol, and methanol. Ablation was performed using a Q-switched Nd:YAG laser with output energy of 230 mJ/pulse for 532 nm wavelength. Ablation time and laser energy fluence were varied for all the liquids. Effects of laser energy fluence, ablation time, and nature of the liquid were reported. The mean size, size distributions, shape, elemental composition, and optical properties of Pt nanoparticles synthesized by PLAL were examined by transmission electron microscopy (TEM, X-ray photoelectron spectroscopy (XPS, and UV-Visible absorption spectroscopy.

Synthesis, crystal structure and anticancer activity of tetrakis(N-isopropylimidazolidine-2-selenone)platinum(II) chloride

Science.gov (United States)

Ahmad, Saeed; Altoum, Ali Osman S.; Vančo, Ján; Křikavová, Radka; Trávníček, Zdeněk; Dvořák, Zdeněk; Altaf, Muhammad; Sohail, Manzar; Isab, Anvarhusein A.

2018-01-01

A Platinum(II) complex of N-isopropylimidazolidine-2-selenone (i-PrImSe), [Pt(i-PrImSe)4]Cl2 (1) was prepared and characterized by elemental analysis, IR and NMR (1H, 13C, 77Se &195Pt) spectroscopy, and X-ray crystallography. The structure of 1 consists of [Pt(i-PrImSe)4]2+ complex ion and chloride counter ions. The platinum(II) atom adopts a distorted square planar geometry. The in vitro antitumor activity of 1 as well as cisplatin, was evaluated by MTT assay against human; ovarian carcinoma A2780 and its cisplatin-resistant subline A2780R, prostate cancer 22Rv1 and breast cancer MCF-7 cell lines. The title complex displayed the activity against the A2780 cells (IC50 = 30.8 μM) at the level comparable to cisplatin (IC50 = 26.8 μM). The interaction studies with sulfur-containing biomolecules revealed its ability to form a variety of intermediates and oxidized species with L-cysteine and reduced glutathione.

The effect of complexation with platinum in polyfluorene derivatives: A photo- and electro-luminescence study

International Nuclear Information System (INIS)

Assaka, Andressa M.; Hu Bin; Mays, Jimmy; Iamazaki, Eduardo T.; Atvars, Teresa D.Z.; Akcelrud, Leni

2011-01-01

The synthesis and characterization of a polymeric structure containing fluorene units statistically linked to 3-cyclohexyl-thiophene and bipyridine PFOTBipy-poly[(4-hexylthiophene-2,5-diyl)(9,9-dihexyl-fluoren-2,7-diyl) -co-(bipyridine-5.5'-diyl)(9,9-dihexyl-fluoren-2,7-diyl)], is reported. The complexation with platinum was possible through the bipyridil units present in 10%, 50% and 100% content. The structure has a fluorenyl moiety between each bipyridine and thiophene groups resulting in a stable and efficient light-emitting polymeric material combining the well known emissive properties of fluorene, the charge mobility generated by thiophene and the electron-transfer properties of a metal complex as well. All the polymers were photo and electroluminescent materials, and showed phosphorescence at low temperatures. Photoluminescence properties were studied by steady state and time resolved spectroscopy and showed changes of both emission peak and relative intensity of the emission bands depending on the relative amount of the platinum complex. The electroluminescence followed the trends found for photoluminescence. The blue emission of the copolymer without platinum is due to the fluorenyl segments and for higher complex contents the emission is characteristic of the aggregates involving the bipyridinyl moieties. Therefore, emission color can be tuned by the complex content. The turn-on voltage was strongly reduced from 22 to 8 V for the 100% complexed copolymer, as compared to the device made with the non complexed one, but the luminance decreased, due to quenching or trapping effects. - Research Highlights: →Statistic copolymer containing fluorine, thiophene and bipyridine. →Complexation of platinum with platinum with bipyridine. →Electroluminescence and electrophosphorescence at low temperatures. →Emission color can be tuned by the complex content.

Inhibition of cartilage degradation and suppression of PGE2 and MMPs expression by pomegranate fruit extract in a model of posttraumatic osteoarthritis.

Science.gov (United States)

Akhtar, Nahid; Khan, Nazir M; Ashruf, Omer S; Haqqi, Tariq M

2017-01-01

Osteoarthritis (OA) is characterized by cartilage degradation in the affected joints. Pomegranate fruit extract (PFE) inhibits cartilage degradation in vitro. The aim of this study was to determine whether oral consumption of PFE inhibits disease progression in rabbits with surgically induced OA. OA was surgically induced in the tibiofemoral joints of adult New Zealand White rabbits. In one group, animals were fed PFE in water for 8 wk postsurgery. In the second group, animals were fed PFE for 2 wk before surgery and for 8 wk postsurgery. Histologic assessment and scoring of the cartilage was per Osteoarthritis Research Society International guidelines. Gene expression and matrix metalloproteinases (MMP) activity were determined using quantitative reverse transcriptase polymerase chain reaction and fluorometric assay, respectively. Interleukin (IL)-1 β, MMP-13, IL-6, prostaglandin (PG)E 2 , and type II collagen (COL2A1) levels in synovial fluid/plasma/culture media were quantified using enzyme-linked immunosorbent assay. Expression of active caspase-3 and poly (ADP-ribose) polymerase p85 was determined by immunohistochemistry. Effect of PFE and inhibitors of MMP-13, mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-κB was studied in IL-1 β-stimulated rabbit articular chondrocytes. Safranin-O-staining and chondrocyte cluster formation was significantly reduced in the anterior cruciate ligament transaction plus PFE fed groups. Expression of MMP-3, MMP-9, and MMP-13 mRNA was higher in the cartilage of rabbits given water alone but was significantly lower in the animals fed PFE. PFE-fed rabbits had lower IL-6, MMP-13, and PGE 2 levels in the synovial fluid and plasma, respectively, and showed higher expression of aggrecan and COL2A1 mRNA. Significantly higher numbers of chondrocytes were positive for markers of apoptosis in the joints of rabbits with OA given water only compared with those in the PFE-fed groups. PFE pretreatment significantly

Dose-response relationships determined in growing rats for various platinum compounds administered with the food. Untersuchungen zu Dosis-Wirkungsbeziehungen verschiedener alimentaer zugefuehrter Platinverbindungen bei wachsenden Ratten

Energy Technology Data Exchange (ETDEWEB)

Bader, R.

1991-02-08

Forming part of a research project entitled 'Emissions of Precious Metals', this study had the aim to describe dose-related responses that occur in growing rats following administration of platinum with the food. The oral intake of diets containing up to to 50 mg platinum/kg food had no detectable influence on the food consumption of the animals, nor were there any deviations from the normal growth curves that could be related to the addition of platinum. Comparisons with the control group pointed to a decline in erythrocytes from 5.88 {+-} 0.55 x 10{sup 6}/{mu}l to 5.11 {+-} 0.50 x 10{sup 6}/{mu}l following administration of 50 ppm PtCl{sub 4} over a period of four weeks. There were no other changes in hematological parameters that attained statistical significance. The treatment group receiving platinum amounts of 50 mg/kg with the diet showed a plasma creatinine value of 1.45 {+-} 0.19 {mu}g/dl, which significantly (p < 0.05) exceeded that of the control group, where creatinine levels remained at 0.70 {+-} 0.50 {mu}g/dl. This leads to the conclusion that the possibility of renal impairment after high oral doses of PtCl{sub 4} is not very remote. (orig./VT).

Combined chemotherapy including platinum derivatives for medulloblastoma. The usefulness as maintenance chemotherapy

International Nuclear Information System (INIS)

Sasaki, Hikaru; Otani, Mitsuhiro; Yoshida, Kazunari; Kagami, Hiroshi; Shimazaki, Kenji; Toya, Shigeo; Kawase, Takeshi

1997-01-01

The authors reviewed 24 cerebellar medulloblastoma patients treated at Keio University to determine usefulness of combined chemotherapy including platinum derivatives (cisplatin, carboplatin) as the induction and maintenance treatment. All patients underwent radical surgery and craniospinal irradiation. Ten received adjuvant chemotherapy other than platinum derivatives (mainly with nitrosourea compounds), five were treated by induction and maintenance chemotherapy including platinum derivatives, and nine patients did not undergo chemotherapy. The progression-free survival rate of patients treated with platinum derivatives was better than that of patients treated with other modes of chemotherapy and also that of patients who did not receive chemotherapy. The results were especially good in the case of four patients treated with maintenance chemotherapy consisting of carboplatin and etoposide, two of whom had been free from relapse beyond the risk period of Collins. The occurrences of toxicity in maintenance chemotherapy with carboplatin and etoposide were limited to transient leucopenia. The present study indicates combined chemotherapy including platinum derivatives benefits patients with medulloblastoma, and could be useful, especially as maintenance treatment. (author)

Synthesis and properties of platinum on multiwall carbon nanotube modified by chitosan

Science.gov (United States)

Fikriyyah, A. K.; Chaldun, E. R.; Indriyati

2018-03-01

Platinum nanoparticles on multiwall carbon nanotubes (Pt/MWCNT) play an important role in fuel cell to convert the chemical energy from a fuel into electricity. In this study, Pt/MWCNT electrocatalysts were prepared by chemical reduction of the metal salts in chitosan as the support. Firstly, commercial MWCNTs were functionalized by oxidative process using a mixture of nitric acid and sulfuric acid. Then, functionalized MWCNTs were mixed with chitosan-acetic acid solution to conduct grafting reaction with NH2 groups in chitosan by solution polymerization method. Platinum nanoparticles were loaded onto the surface of the MWCNTs after hexachloroplatinic acid was reduced by sodium hydroxide solution. The result showed that Pt was attached on MWCNT based on analysis from EDS, XRD, and UV Vis Spectroscopy. UV Vis analysis indicates the plasmon absorbance band of Pt nanoparticles in Pt/MWCNT, while XRD analysis confirmed the size of Pt particle in nanometer. This elucidates the potential procedure to synthesize Pt/MWCNT using chitosan.

Structure of matrix metalloproteinase-3 with a platinum-based inhibitor.

Science.gov (United States)

Belviso, Benny Danilo; Caliandro, Rocco; Siliqi, Dritan; Calderone, Vito; Arnesano, Fabio; Natile, Giovanni

2013-06-18

An X-ray investigation has been performed with the aim of characterizing the binding sites of a platinum-based inhibitor (K[PtCl3(DMSO)]) of matrix metalloproteinase-3 (stromelysin-1). The platinum complex targets His224 in the S1' specificity loop, representing the first step in the selective inhibition process (PDB ID code 4JA1).

75 FR 23710 - Order Finding That the ICE PG&E Citygate Financial Basis Contract Traded on the...

Science.gov (United States)

2010-05-04

... ICE maintains exclusive rights over IPI's bidweek price indices. As a result, no other exchange can... this contract has the exclusive right to base its settlement on the IPI PG&E Citygate Index price... Contract Traded on the IntercontinentalExchange, Inc., Performs a Significant Price Discovery Function...

Geochronology and characteristics of Ni-Cu-(PGE) mineralization at Rožany, Lusatian Granitoid Complex, Czech Republic

Czech Academy of Sciences Publication Activity Database

Haluzová, Eva; Ackerman, Lukáš; Pašava, J.; Jonášová, Šárka; Svojtka, Martin; Hrstka, Tomáš; Veselovský, F.

2015-01-01

Roč. 60, č. 4 (2015), s. 219-236 ISSN 1802-6222 R&D Projects: GA ČR GA13-15390S Institutional support: RVO:67985831 Keywords : Ni-Cu-(PGE) * Lusatia * Re-Os * Bohemian Massif * sulphur Subject RIV: DD - Geochemistry Impact factor: 1.326, year: 2015

Optimising the treatment of the partially platinum-sensitive relapsed ovarian cancer patient

Directory of Open Access Journals (Sweden)

Nicoletta Colombo

2014-12-01

Full Text Available The choice of second-line chemotherapy in patients with recurrent ovarian cancer (ROC is complex, with several factors to be considered, the most important of which is the length of the platinum-free treatment interval (PFI. Recently ROC patients have been further stratified into platinum sensitive (PS, partially platinum sensitive (PPS and platinum resistant (PR subgroups depending on the length of the PFI. Response to second-line therapy, progression-free survival (PFS and overall survival (OS are linked to the PFI, all of them improving as the PFI increases. Consequently, there is increasing interest in PFI extension strategies with platinum-free therapeutic options. Such strategies are currently being studied in patients with partially platinum-sensitive disease (PFI 6-12 months, as the treatment of these patients remains clinically challenging. A non-platinum option, trabectedin + pegylated liposomal doxorubicin (PLD combination, has been evaluated in ROC patients in the pivotal phase III OVA-301 study. The OVA-301 study differed from previous trials in the same setting as it included only patients who were not expected to benefit from or who were ineligible for or who were unwilling to receive re-treatment with platinum-based chemotherapy, including those with PPS and PR disease. Subset analysis of patients with PPS disease in OVA-301 showed that the trabectedin + PLD combination significantly improved PFS compared with PLD alone; median PFS 7.4 versus 5.5 months, p=0.0152. Final survival data from the same subset of patients, showed that trabectedin + PLD also achieved a significant 36% decrease in the risk of death compared with PLD alone (HR=0.64; 95% CI, 0.47–0.88; p=0.0027. Median overall survival (OS was 22.4 months in the trabectedin + PLD arm versus 16.4 months in the PLD arm. This represents a statistically significant 6-month improvement in median OS in patients treated with trabectedin + PLD compared to those treated with PLD

Electrochemical behaviour of platinum in hydrogen peroxide solution (1963)

International Nuclear Information System (INIS)

Prost, G.H.

1963-06-01

The relative stability of hydrogen peroxide in aqueous solution at 25 deg. C, allows its amperometric determination from the theory, using either its cathodic reduction or its anodic oxidation. The cathodic reduction yields a wave on a platinum electrode only when some oxygen is present in the solution. It cannot, therefore, be used for electrochemical determination. On the other hand, the anodic oxidation on platinum produces a wave which might be used. However, a passivation of platinum occurs at the same time. This passivation process is studied by means of potentio-kinetic, potentio-static, intensio-static curves and of pH measurements in the vicinity of the anode. A mechanism for passivation is presented, which takes into account the role of hydrogen peroxide as a reducing agent. This passivation rules out any analytical application of the oxidation reaction of hydrogen peroxide. (author) [fr

Properties of Group Five and Group Seven transactinium elements

Energy Technology Data Exchange (ETDEWEB)

Wilk, Philip A. [Univ. of California, Berkeley, CA (United States)

2001-05-01

The detection and positive identification of the short-lived, low cross section isotopes used in the chemical studies of the heaviest elements are usually accomplished by measuring their alpha-decay, thus the nuclear properties of the heaviest elements must be examined simultaneously with their chemical properties. The isotopes ²²⁴ Pa and ^266,267 Bh have been studied extensively as an integral part of the investigation of the heaviest members of the groups five and seven of the periodic table. The half-life of ²²⁴ Pa was determined to be 855 ±19 ms by measuring its alpha-decay using our rotating wheel, solid state detector system at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. Protactinium was produced by bombardment of a bismuth target. New neutron rich isotopes, ²⁶⁷ Bh and ²⁶⁶ Bh, were produced in bombardments of a ²⁴⁹ Bk target and their decay was observed using the rotating wheel system. The ²⁶⁶ Bh that was produced decays with a half-life of approximately 1 s by emission of alpha particles with an average energy of 9.25 plus/minus 0.03 MeV. ²⁶⁷ Bh was observed to decay with a 17 s half-life by emission of alpha-particles with an average energy of 8.83 plus/minus 0.03 MeV. The chemical behavior of hafnium, Ha (element 105) was investigated using the fast on-line continuous liquid extraction and detection system SISAK-LISSY. Hafnium was not observed in this experiment following transport and extraction. Protactinium was used as on-line test of the apparatus to determine the experimental efficiency of the entire system. Unfortunately, the amount of protactinium observed after the extraction, compared to the amount produced, was extremely small, only 2.5%. The extraction of the protactinium isotope indicated the efficiency of the apparatus was too low to observe the extraction of hafnium. The chemical behavior of oxychloride compounds of bohrium was

Origin of the different behavior of some platinum decorated nanocarbons towards the electrochemical oxidation of hydrogen peroxide

Energy Technology Data Exchange (ETDEWEB)

Malara, A. [Dipartimento di Ingegneria dell' Informazione, delle Infrastrutture e dell' Energia Sostenibile (DIIES), Università “Mediterranea”, 89122 Reggio Calabria (Italy); Leonardi, S.G.; Bonavita, A. [Dipartimento di Ingegneria Elettronica, Chimica ed Ingegneria Industriale (DIECII), Università di Messina, 98166 Messina (Italy); Fazio, E. [Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra (MIFT), Università di Messina, 98166 Messina (Italy); Stelitano, S. [Dipartimento di Fisica (DF), Università della Calabria, 87036 Arcavacata di Rende (Italy); Neri, G. [Dipartimento di Ingegneria Elettronica, Chimica ed Ingegneria Industriale (DIECII), Università di Messina, 98166 Messina (Italy); Neri, F. [Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra (MIFT), Università di Messina, 98166 Messina (Italy); Santangelo, S., E-mail: saveria.santangelo@unirc.it [Dipartimento di Ingegneria Civile, dell' Energia, dell' Ambiente e dei Materiali (DICEAM), Università “Mediterranea”, 89122 Reggio Calabria (Italy)

2016-12-01

The electrochemical behavior of different platinum-decorated nanocarbons (Pt@C) towards the oxidation of hydrogen peroxide (H{sub 2}O{sub 2}) was investigated. Three different types of nanocarbons were considered: i) carbon black, ii) dahlia-like carbon nanohorns and iii) carbon nanotubes, which included both commercial (single-wall and multi-wall) and laboratory prepared (multi-wall) samples. Shape and size distribution of the platinum nanoparticles and morphology of the nanocarbons were analyzed by transmission electron microscopy. Their nanostructure was investigated by micro-Raman spectroscopy, while elemental composition of the samples and chemical bonding states were studied by X-ray photoelectron spectroscopy. Electrochemical behavior towards H{sub 2}O{sub 2} oxidation was evaluated by means of cyclic voltammetry modifying the working screen-printed carbon electrode surface with the prepared Pt@C nanocomposites. Data obtained suggest that the size and dispersion of the Pt nanoparticles play a key role in increasing the sensitivity towards H{sub 2}O{sub 2} detection. Thanks to the presence of smaller and more dispersed platinum particles and of a greater amount of platinum hydroxide, acting as intermediary in the H{sub 2}O{sub 2} oxidation process, Pt@dahlia-like carbon nanohorns result to be the most promising platform for the development of H{sub 2}O{sub 2} electrochemical sensors. - Highlights: • Different nanocarbons are decorated with Pt nanoparticles by wet impregnation method. • Pt@C-based hybrids are tested as active materials for sensing of hydrogen peroxide. • Sensor based on Pt@dahlia-like carbon nanohorns is the most performing device. • The origin of the different electrochemical behaviour is investigated. • Pt@C sensing performances are correlated with their structural and surface properties.

4-aminoquinoline analogues and its platinum (II) complexes as antimalarial agents.

Science.gov (United States)

de Souza, Nicolli Bellotti; Carmo, Arturene M L; Lagatta, Davi C; Alves, Márcio José Martins; Fontes, Ana Paula Soares; Coimbra, Elaine Soares; da Silva, Adilson David; Abramo, Clarice

2011-07-01

The high incidence of malaria and drug-resistant strains of Plasmodium have turned this disease into a problem of major health importance. One of the approaches used to control it is to search for new antimalarial agents, such as quinoline derivates. This class of compounds composes a broad group of antimalarial agents, which are largely employed, and inhibits the formation of β-haematin (malaria pigment), which is lethal to the parasite. More specifically, 4-aminoquinoline derivates represent potential sources of antimalarials, as the example of chloroquine, the most used antimalarial worldwide. In order to assess antimalarial activity, 12 4-aminoquinoline derived drugs were obtained and some of these derivatives were used to obtain platinum complexes platinum (II). These compounds were tested in vivo in a murine model and revealed remarkable inhibition of parasite multiplication values, whose majority ranged from 50 to 80%. In addition they were not cytotoxic. Thus, they may be object of further research for new antimalarial agents. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Cerium oxide and platinum nanoparticles protect cells from oxidant-mediated apoptosis

International Nuclear Information System (INIS)

Clark, Andrea; Zhu Aiping; Sun Kai; Petty, Howard R.

2011-01-01

Catalytic nanoparticles represent a potential clinical approach to replace or correct aberrant enzymatic activities in patients. Several diseases, including many blinding eye diseases, are promoted by excessive oxidant stress due to reactive oxygen species (ROS). Cerium oxide and platinum nanoparticles represent two potentially therapeutic nanoparticles that de-toxify ROS. In the present study, we directly compare these two classes of catalytic nanoparticles. Cerium oxide and platinum nanoparticles were found to be 16 ± 2.4 and 1.9 ± 0.2 nm in diameter, respectively. Using surface plasmon-enhanced microscopy, we find that these nanoparticles associate with cells. Furthermore, cerium oxide and platinum nanoparticles demonstrated superoxide dismutase catalytic activity, but did not promote hemolytic or cytolytic pathways in living cells. Importantly, both cerium oxide and platinum nanoparticles reduce oxidant-mediated apoptosis in target cells as judged by the activation of caspase 3. The ability to diminish apoptosis may contribute to maintaining healthy tissues.

A novel reusable platinum nanocatalyst

International Nuclear Information System (INIS)

Zhou Weiqiang; Wang Jing; Wang Chuanyi; Du Yukou; Xu Jingkun; Yang Ping

2010-01-01

Recyclability of noble metal catalysts is a challenging issue when dealing with their industrial applications. Smart pH-sensitive Pt nanoparticles were successfully prepared for the first time by using octa(N,N-diacetic acid phenylamine)silsesquioxane (OAPAS) as a macromolecular protective agent. As-prepared Pt nanoparticles can self-aggregate or redisperse by only changing the pH of the system solution. In the weak acidic or alkaline solution (pH > 4.0), the Pt nanoparticles dispersed homogenously; while in the acidic solution (pH = 2.5), they self-aggregated. The dynamic self-aggregation and redispersion processes of the Pt nanoparticles driven by pH changes were revealed by transmission electron microscopy measurements. Electrocatalytic experiments proved that the platinum nanoparticles as a recyclable catalyst showed excellent activity for the hydrogenation of aldehyde after runs of five times. Such platinum nanoparticles are thereby anticipated to have great potential functioning as 'smart' catalysts for industrial applications.

RIA of PGFsub(2α) and PGE2 in biological samples of different origin: comparison with the mass fragmentographic technique

International Nuclear Information System (INIS)

Cattabeni, F.; Borghi, C.; Folco, G.C.; Nicosia, S.; Spagnuolo, C.

1979-01-01

The aim of this paper is to describe some results obtained measuring PGFsub(2α) and PGE 2 with bioassay, RIA and mass fragmentography in samples of different biological origin such as rat brain cortex and human urine of normal subjects and patients with Bartter's Syndrome. The results reported here clearly indicate that the assay of PGFsub(2α) and PGE 2 require an accurate validation with different analytical techniques. In fact, RIA of PGFsub(2α) gave different results if the samples were of different origin. It can be concluded that all the methods today available for PGs measurements need to be accurately validated utilizing different assays and that this validation is required everytime the sample matrix is changed. (Auth.)

Stability of Porous Platinum Nanoparticles: Combined In Situ TEM and Theoretical Study

DEFF Research Database (Denmark)

Chang, Shery L. Y.; Barnard, Amanda S.; Dwyer, Christian

2012-01-01

Porous platinum nanoparticles provide a route for the development of catalysts that use less platinum without sacrificing catalytic performance. Here, we examine porous platinum nanoparticles using a combination of in situ transmission electron microscopy and calculations based on a first-principles......-parametrized thermodynamic model. Our experimental observations show that the initially irregular morphologies of the as-sythesized porous nanoparticles undergo changes at high temperatures to morphologies having faceted external surfaces with voids present in the interior of the particles. The increasing size of stable...

78 FR 42436 - Procedures To Establish Appropriate Minimum Block Sizes for Large Notional Off-Facility Swaps and...

Science.gov (United States)

2013-07-16

... (ICE). Gold (COMEX and NYSE Liffe).. 2,500 troy oz. Goldman Sachs Commodity Index 5,000 times dollars... (NYMEX) 1,000 troy oz. PG&E Citygate Basis (ICE and 62,500 MMBtu. NYMEX). PJM Western Hub Real Time Off...). Platinum (NYMEX) 500 troy oz. Rainfall Index (CME)......... 10,000 times dollars. index. Rough Rice (CBOT...

In vitro effects of platinum compounds on renal cellular respiration in mice.

Science.gov (United States)

Almarzooqi, Saeeda-S; Alfazari, Ali-S; Abdul-Kader, Hidaya-M; Saraswathiamma, Dhanya; Albawardi, Alia-S; Souid, Abdul-Kader

2015-01-01

Cisplatin, carboplatin and oxaliplatin are structurally-related compounds, which are commonly used in cancer therapy. Cisplatin (Platinol(®)) has Boxed Warning stating: "Cumulative renal toxicity associated with PLATINOL is severe", while carboplatin and oxaliplatin are less nephrotoxic. These drugs form platinum adducts with cellular DNA. Their bindings to cellular thiols (e.g., glutathione and metallothionein) are known to contribute to drug resistance while thiol depletion augments platinum toxicity. Using phosphorescence oxygen analyzer, this study investigated the effects of platinum drugs on renal cellular respiration (mitochondrial O2 consumption) in the presence and absence of the thiol blocking agent N-ethylmaleimide (used here as a model for thiol depletion). Renal cellular ATP was also determined. Kidney fragments from C57BL/6 mice were incubated at 37 °C in Krebs-Henseleit buffer (gassed with 95% O2:5% CO2) with and without 100 μM platinum drug in the presence and absence of 100 μM N-ethylmaleimide for ≤ 6 h. Platinum drugs alone had no effects on cellular respiration (P ≥ 0.143) or ATP (P ≥ 0.161). N-ethylmaleimide lowered cellular respiration (P ≤ 0.114) and ATP (P = 0.008). The combination of platinum drug and N-ethylmaleimide significantly lowered both cellular respiration (P ≤ 0.006) and ATP (P ≤ 0.003). Incubations with N-ethylmaleimide alone were associated with moderate-to-severe tubular necrosis. Incubations with cisplatin+N-ethylmaleimide vs. cisplatin alone produced similar severities of tubular necrosis. Tubular derangements were more prominent in carboplatin+N-ethylmaleimide vs. carboplatin alone and in oxaliplatin+N-ethylmaleimide vs. oxaliplatin alone. These results demonstrate the adverse events of thiol depletion on platinum-induced nephrotoxicities. The results suggest cellular bioenergetics is a useful surrogate biomarker for assessing drug-induced nephrotoxicities.

Electrodeposition of platinum metals and alloys from chloride melts

Directory of Open Access Journals (Sweden)

Saltykova N.A.

2003-01-01

Full Text Available The structure of platinum metals and their alloys deposited by the electrolysis of chloride melts have been investigated. The cathodic deposits were both in the form of compact layers and dendrites. All the alloys of platinum metals obtained are solid solutions in the whole range of composition. Depending on the experimental conditions the layers had columnar, stratum and spiral (dissipative structures. The stratum and dissipative structures were observed in the case of alloys only.

The exchange reaction between deuterium and water vapour on platinum deposited over a hydrophobic support

International Nuclear Information System (INIS)

Itsuo, Iida; Junko, Kato; Kenzi, Tamuru

1977-01-01

Isotope exchange reaction between deuterium gas and water vapour at room temperature and below on platinum deposited on hydrophobic supports such as polytetrafluoroethylene (PTFE) or Porapak Q (copolymer of styrene and divinylbenzene) was studied and the results were compared with those of the exchange reaction on platinum over hydrophilic support such as alumina. It was demonstrated that the exchange reaction at temperatures below the boiling point of water is markedly retarded by the multilayer adsorption of water over the platinum catalyst deposited on hydrophilic support, whereas the platinum catalyst on hydrophobic support exhibited a high catalytic activity, being not retarded by the water, forming no multilayer of adsorbed water over platinum surface. Therefore in the case of the hydrogen isotope exchange reaction on platinum over hydrophobic support, the chemical exchange rate can be measured even under a saturated vapour pressure of water. The surface area of platinum was estimated by hydrogen chemisorption and hydrogen titration and specific activities of the catalyst were calculated at both room temperature and freezing point of water, which revealed that the specific rate of this reaction does not differ so much over various supports. (orig.) [de

Electrochemical behavior of titanium implanted with platinum

International Nuclear Information System (INIS)

Thompson, N.G.; Lichter, B.D.; Appleton, B.R.; Kelly, E.J.; White, C.W.

1979-01-01

The following conclusions apply to Ti(Pt) near-surface alloys studied. (1) Open-circuit corrosion measurements show that accumulation of platinum may occur at a surface concentration of 0.32 atomic percent Pt while no accumulation occurs at 0.16 atomic percent Pt. However, these results do not allow a distinction as to cause of accumulation to be made between concentration effects and effects due to the presence of an oxide film. (2) Potentiostatic corrosion at -0.450 V (active corrosion) establish that little or no accumulation of platinum occurs at an oxide-free surface for concentrations less than 0.086 atomic percent Pt; whereas, a large amount of accumulation occurs for a distribution with a peak concentration of 0.83 atomic percent Pt. (3) An initial distribution having a peak concentration of 0.32 atomic percent platinum is sufficient to induce natural passivity in titanium and bring a freely corroding sample to a potential of 0.269 V. This is nearly the applicable reversible potential (-0.260 V) for the hydrogen reaction in 1N H 2 SO 4 . (4) Of three samples which showed accumulation, platinum was eventually lost for two of these samples (0.32 atomic percent, open-circuit corrosion; 0.83 atomic percent, potentiostatic corrosion). The remaining sample (9.1 atomic percent, open-circuit corrosion) maintained the maximum possible potential of -0.260 V for the length of the experiment (approx. 30 days). (5) For samples which had been polarized at -0.300 to -0.340 V and which had eventually reverted to the behavior of pure Ti, post corrosion RBS measurements reveal that a substantial fraction of the Pt fluence is retained on the surface in an electrochemically inactive state

Aerosolized PGE1, PGI2 and nitroprusside protect against vascular leakage in lung ischaemia-reperfusion.

Science.gov (United States)

Schütte, H; Löckinger, A; Seeger, W; Grimminger, F

2001-07-01

High permeability oedema is an important feature in lung injury secondary to ischaemia-reperfusion. This study investigated the influence of aerosolized prostaglandin E1 (PGE1), prostaglandin I2 (PCI2) and the nitric oxide (NO)-donor, sodium nitroprusside (SNP) on microvascular barrier function in pulmonary ischaemia-reperfusion. Buffer-perfused rabbit lungs were exposed to 180 or 210 min of warm ischaemia while maintaining anoxic ventilation and a positive intravascular pressure. Reperfusion provoked a transient, mostly precapillary elevation of vascular resistance, followed by a severe increase of the capillary filtration coefficient (Kfc) versus nonischaemic controls (3.17+/-0.34 versus 0.85+/-0.05 cm3 x s(-1) cmH2O(-1) x g(-1) x 10(-4) after 30 min of reperfusion), and progressive oedema formation. Short-term aerosolization of SNP, PGE1 or PGI2 at the beginning of ischaemia largely suppressed the Kfc increase (1.36+/-0.22, 1.32+/-0.23 and 1.32+/-0.22 cm3 x s(-1) x cmH2O(-1) x g(-1) x 10(-4), respectively) and oedema formation. In contrast, application prior to reperfusion was much less effective, with some reduction of Kfc increase by PGI2 and SNP and no effect of PGE, (1.79+/-0.31, 2.2+/-0.53 and 3.2+/-0.05 cm3 x s(-1) x cmH2O(-1) x g(-1) x 10(-4), respectively). Haemodynamics, including microvascular pressure, were only marginally affected by the chosen doses of aerosolized vasodilators. It is concluded that short-term aerosolization of prostaglandin E1, prostaglandin I2 and sodium nitroprusside at the onset of ischaemia is highly effective in maintaining endothelial barrier properties in pulmonary ischaemia-reperfusion. This effect is apparently attributable to nonvasodilatory mechanisms exerted by these agents. Alveolar deposition of prostaglandins and/or nitric oxide donors by the aerosol technique may offer pulmonary protection in ischaemia-reperfusion injury.

Increased synthesis of high-molecular-weight cPLA2 mediates early UV-induced PGE2 in human skin.

Science.gov (United States)

Gresham, A; Masferrer, J; Chen, X; Leal-Khouri, S; Pentland, A P

1996-04-01

Ultraviolet light (UV) B-induced inflammation is characterized by dramatic increases in prostaglandin E2 (PGE2) synthesis due to enhanced arachidonate deacylation from the membrane. Therefore, the effect of UV on sythesis, mass, and distribution of the high-molecular-weight phospholipase A2 (cPLA2) in cultured human keratinocytes and human skin was studied. The 105-kDa cPLA2 was demonstrated to be the critical enzyme in UV-induced PGE2 synthesis and erythema in the first 6 h postirradiation. Immunoprecipitation of 35S-labeled protein showed cPLA2 synthesis increased three- to fourfold 6 h after irradiation. Immunoprecipitated 32P-labeled cPLA2 demonstrated phosphorylation of cPLA2 was concurrently induced, suggesting that UV also activates cPLA2. This increase in cPLA2 synthesis and activation also closely correlated with increased PGE2 synthesis and [3H]arachidonic acid release and was effectively blocked by both an S-oligonucleotide antisense to cPLA2 and methyl arachidonate fluorophosphate, a specific inhibitor of cPLA2. Biopsy and histochemical examination of erythematous sites expressed increased amounts of cPLA2 whereas nonerythematous irradiated sites did not. In contrast, cyclooxygenase-1 and -2 in cultures and skin explants were unaffected 6 h post-UV, and no change in cyclooxygenase activity was observed at this time. These results suggest that increased cPLA2 synthesis occurs only when skin is exposed to UV doses that are sufficient to cause erythema and indicate expression of cPLA2 participates in acute UV inflammation.

Electrochemical and microstructural characterization of platinum supported on glassy carbon

Directory of Open Access Journals (Sweden)

Terzić Sanja

2007-01-01

Full Text Available The effect of the electrochemical oxidation of glassy carbon on the deposition of platinum particles and the electrocatalytic activity of platinum supported on oxidized glassy carbon were studied for methanol oxidation in H2SO4 solution. Platinum was potentiostatically deposited from H2SO4 + 6mM H2PtCl6 solution. Glassy carbon was anodically polarized in 1 M NaOH at 1.41 V (SCE for 35 and 95 s and in 0.5 M H2SO4 at 2V (SCE for 35; 95 s and 2.25 V for 35 and 95 s. Electrochemical treatment of the GC support leads to a better distribution of platinum on the substrate and has remarkable effect on the activity. The activity of the Pt/GCox electrode for methanol oxidation is larger than that of polycrystalline Pt and by more than one order of magnitude larger than that of a Pt/GC electrode. This increase in activity indicates the pronounced role of the organic residues of the GC support on the properties of Pt particles deposited on glassy carbon.

Enhancement of micropore filling of water on carbon black by platinum loading

Energy Technology Data Exchange (ETDEWEB)

Miyajima, Naoya, E-mail: miyajima@yamanashi.ac.jp [Interdisciplinary Graduate School of Medicine and Engineering, 4-3-11 Takeda, Kofu, Yamanashi 400-8511 (Japan); Hatori, Hiroaki [Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan); Radovic, Ljubisa R. [Department of Energy and Geo-Environmental Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Yamada, Yoshio [Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan)

2010-10-15

Two kinds of typical carbons, carbon black and activated carbon fibers, were modified with platinum nanoparticles without changing their original pore structures. The surface properties of the modified carbons were investigated by measuring of water adsorption isotherms. Micropore filling of water was facilitated by the presence of platinum nanoparticles on the surface of the carbon black. On the other hand, such a filling effect was not observed in the case of the activated carbon fibers. A critical content and/or size of platinum nanoparticles could be required to promote efficiently the water adsorption.

Determination of trace elements: Neutron-activation analysis in geochemistry and cosmochemistry

International Nuclear Information System (INIS)

Kolesov, G.M.

1994-01-01

Geochemistry, like cosmochemistry, open-quotes studies chemical elements hor-ellipsis of the crust and hor-ellipsis the Earth hor-ellipsis their history, their distribution hor-ellipsis their genetic hor-ellipsis connectionsclose quotes and is based on data on the abundance and distribution of elements obtained by various analytical methods. Neutron-activation analysis (NAA) plays a particular role in this respect. This is due to its high sensitivity (detection limit as small as 10 -14 g), which makes possible the use of samples of arbitrary mass, and also due to the possibility of obtaining information about composition without destruction of the object, conserving, if required, the unique material under investigation. Of the most interest are the data on the contents for a number of trace elements (at a level of 10 -7 - 10 -4 %), among which are rare-earth elements (REE), U, Th, Zr, Hf, Ta, W, Ga, Ni, Rb, Cs, platinum-group metals, Ag, Au, etc. These elements are considered as indicators of geochemical processes associated with the genesis and evolution of solar system bodies in early and more recent stages of evolution; they are also used to study processes and phenomena at zone boundaries: river-sea, ocean-atmosphere, and so on. The aim of this work is to show the capabilities of NAA in the determination of trace elements

Binding of dioxouranium(VI) and platinum(II) to ribonuclease-S

Energy Technology Data Exchange (ETDEWEB)

Marzotto, A [Consiglio Nazionale delle Ricerche, Padua (Italy). Lab. di Chimica e Tecnologia dei Radioelementi

1976-12-01

The preferred binding sites of RNase-S to dioxouranium(VI) and platinum(II) has been determined by Wyckoff et al., (J.Biol.Chem., v242, 1967, p.3749; ibid p.3984; ibid v245, 1970, p.305) elaborating protein and of heavy-atom derivatives reported by Wyckoff and coworkers. The major sites are exposed at the surface of the protein molecule and are not directly involved in the biological properties; the coordination geometry of the groups bound to the metal ions have been examined in comparison with model compounds.

On the enzymatic formation of platinum nanoparticles

International Nuclear Information System (INIS)

Govender, Y.; Riddin, T. L.; Gericke, M.; Whiteley, C. G.

2010-01-01

A dimeric hydrogenase enzyme (44.5 and 39.4 kDa sub units) was isolated in a 39.5% yield from the fungus Fusarium oxysporum and purified 4.64-fold by ion exchange chromatography on Sephacryl S-200. Characterisation of the enzyme afforded pH and temperature optima of 7.5 and 38 o C, respectively, a half-life stability of 36 min and a V max and K m of 3.57 nmol min -1 mL -1 and 2.25 mM, respectively. This enzyme was inhibited (non-competitively) by hydrogen hexachloroplatinic acid (H 2 PtCl 6 ) at 1 or 2 mM with a K i value of 118 μM. Incubation of the platinum salt with the pure enzyme under an atmosphere of hydrogen and optimum enzyme conditions (pH 7.5, 38 o C) afforded o C) over 90% reduction took place after the same length of time. Cell-free extract from the fungal isolates produced nearly 90% bioreduction of the platinum salt under both pH and temperature conditions. The bioreduction of the platinum salt by a hydrogenase enzyme takes place by a passive process and not an active one as previously understood.

A randomized phase II study of carboplatin plus pegylated liposomal doxorubicin versus carboplatin plus paclitaxel in platinum sensitive ovarian cancer patients: a Hellenic Cooperative Oncology Group study

Directory of Open Access Journals (Sweden)

Briasoulis Evangelos

2010-01-01

Full Text Available Abstract Background Platinum-based combinations are the standard second-line treatment for platinum-sensitive ovarian cancer (OC. This randomized phase II study was undertaken in order to compare the combination of carboplatin and pegylated liposomal doxorubicin (LD with carboplatin and paclitaxel (CP in this setting. Methods Patients with histologically confirmed recurrent OC, at the time of or more than 6 months after platinum-based chemotherapy, were randomized to six cycles of CP (carboplatin AUC5 + paclitaxel 175 mg/m2, d1q21 or CLD (carboplatin AUC5 + pegylated LD 45 mg/m2, d1q28. Results A total of 189 eligible patients (CP 96, CLD 93, with a median age of 63 years, median Performance Status (PS 0 and a median platinum free interval (PFI of 16.5 months, entered the study. Discontinuation due to toxicity was higher in the CP patients (13.5% versus 3%, P = 0.016. The overall response rate was similar: CP 58% versus CLD 51%, P = 0.309 (Complete Response; CR 34% versus 23% and there was no statistical difference in time-to-progression (TTP or overall survival (OS; TTP 10.8 months CP versus 11.8 CLD, P = 0.904; OS 29.4 months CP versus 24.7 CLD, P = 0.454. No toxic deaths were recorded. Neutropenia was the most commonly seen severe toxicity (CP 30% versus CLD 35%. More frequent in CLD were severe thrombocytopenia (11% versus 2%, P = 0.016, skin toxicity and Palmar-plantar erythrodysesthesia (PPE grade 1-2 (38% versus 9%, PP = 0.029, 20% versus 5%, P = 0.003. PS and PFI were independent prognostic factors for TTP and OS. Conclusions The combination of pegylated LD with carboplatin is effective, showing less neurotoxicity and alopecia than paclitaxel-carboplatin. It thus warrants a further phase III evaluation as an alternative treatment option for platinum-sensitive OC patients. Trial Registration Australian New Zealand Clinical Trials Registry: ACTRN12609000436279

Rhodium in car exhaust tips by total automatic activation analysis

International Nuclear Information System (INIS)

Grass, F.; Westphal, G.P.; Lemmel, H.; Sterba, J.

2007-01-01

Exhaust systems of modern cars contain catalysts for the reduction of CO, NO x and hydrocarbons. These catalysts are made of ceramic materials with a large surface on which platinum metals catalyse the oxidation. The catalysts contain approximately 2 g of platinum and 0.4 g of rhodium. Recently platinum is being replaced by palladium. During driving the platinum-group elements (PGEs) are expelled from the tip in fine particles and are deposited in the environment. For a projected study of emissions from cars driven on streets and highways it is important to know which elements can be measured by short time activation analysis without any chemical procedure. (author)

Production of atomic negative ion beams of the Group IA elements

International Nuclear Information System (INIS)

Alton, G.D.; Mills, G.D.

1988-01-01

A method has been developed which enables the direct sputter generation of atomic negative ion beams of all members of the Group IA elements (Li, Na, K, Rb, and Cs). The method consists of the use of sputter samples formed by pressing mixtures of the carbonates of the Group IA elements and 10% (atomic) Cu, Ag, or other metal powder. The following intensities are typical of those observed from carbonate samples subjected to /approximately/3 KeV cesium ion bombardment: Li - : ≥0.5 μA; Na - : ≥0.5 μA; K - : ≥0.5 μA; Rb - : ≥0.5 μA; Cs - : ≥0.2 μA. 7 refs., 2 figs., 1 tab

Discovery of the calcium, indium, tin, and platinum isotopes

International Nuclear Information System (INIS)

Amos, S.; Gross, J.L.; Thoennessen, M.

2011-01-01

Currently, twenty-four calcium, thirty-eight indium, thirty-eight tin, and thirty-nine platinum isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented. - Highlights: Documentation of the discovery of all calcium, indium, tin and platinum isotopes. → Summary of author, journal, year, place and country of discovery for each isotope. → Brief description of discovery history of each isotope.

The relationship between debt levels and total shareholder return of JSE-listed platinum companies

Directory of Open Access Journals (Sweden)

Sandra Jooste

2016-02-01

Full Text Available The purpose of this study is to investigate empirically whether there is a positive correlation between debt levels and total shareholder return (TSR of platinum JSE-listed companies. The study field comprised annual analyses for 12 companies listed under the Platinum and Precious Metals sector on the JSE Ltd for the 14-year period 2000 to 2013. The results of the study were inconclusive as a statistically significant positive correlation between changes in debt levels and changes in TSR could only be found in two of these years. The core audience of the study will be the management of South African platinum companies considering changes in their capital structure, and investors considering investment in a listed platinum company. The contribution of the study is therefore to add to the body of literature on capital structure decisions from a South African platinum mine context

Studies of kinematic elements in two multicenter sunspot groups

International Nuclear Information System (INIS)

Korobova, Z.B.

1983-01-01

Some features of kinematic elements (KE) in two multicenter sunspot groups were studied using Tashkent full-disc white light heliograms. KE and morphological elements do not reveal any relationship. A KE coincides with a unipolar or multipolar spot or with part of a spot. It may also contain an extended stream including several spots. Relation of KE to large-scale photospheric magnetic fields is less clear. The line of polarity reversal is, in most cases, the deviding line between two adjacent KE. At the same time, a KE can contain spots of both polarities. Sunspot trajectories in the leading polarity regions show the best similarity. Interactions of KE are greatly influenced by the meridional drift. (author)

Platinum-induced structural collapse in layered oxide polycrystalline films

International Nuclear Information System (INIS)

Wang, Jianlin; Liu, Changhui; Huang, Haoliang; Fu, Zhengping; Peng, Ranran; Zhai, Xiaofang; Lu, Yalin

2015-01-01

Effect of a platinum bottom electrode on the SrBi 5 Fe 1−x Co x Ti 4 O 18 layered oxide polycrystalline films was systematically studied. The doped cobalt ions react with the platinum to form a secondary phase of PtCoO 2 , which has a typical Delafossite structure with a weak antiferromagnetism and an exceptionally high in-plane electrical conductivity. Formation of PtCoO 2 at the interface partially consumes the cobalt dopant and leads to the structural collapsing from 5 to 4 layers, which was confirmed by X-ray diffraction and high resolution transmission electron microscopy measurements. Considering the weak magnetic contribution from PtCoO 2 , the observed ferromagnetism should be intrinsic of the Aurivillius compounds. Ferroelectric properties were also indicated by the piezoresponse force microscopy. In this work, the platinum induced secondary phase at the interface was observed, which has a strong impact on Aurivillius structural configuration and thus the ferromagnetic and ferroelectric properties

VB Platinum Tile & Carpet, Inc. Information Sheet

Science.gov (United States)

VB Platinum Tile & Carpet, Inc. (the Company) is located in Bristow, Virginia. The settlement involves renovation activities conducted at a property constructed prior to 1978, located in Washington, DC.

Nanoporous sputtered platinum-iridium-thinfilms for medical and energy applications; Nanoporoese gesputterte Platin-Iridium-Schichten fuer Anwendungen in der Medizin- und Energietechnik