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Sample records for osmium phosphides

  1. Aluminum phosphide

    Integrated Risk Information System (IRIS)

    Aluminum phosphide ; CASRN 20859 - 73 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinoge

  2. Osmium in the rivers

    SciTech Connect

    Sharma, M. |; Wasserburg, G.J.

    1997-12-01

    There is a large uncertainty in our understanding of the behavior of osmium during weathering and transport into deep oceans and the osmium budget of the oceans. The problem stems chiefly from the lack of osmium data on the dissolved load in the rivers and in the estuaries. In this study, the concentration and isotopic composition of osmium have been determined in three North American rivers (the Mississippi, the Columbia, and the Connecticut) and one river draining central Europe and flowing into the Baltic Sea (the Vistula). Osmium concentration in the Mississippi and the Vistula is about 45 femto mol kg{sup -1}; it is about 14 and 15 femto mol kg{sup -1} for the Connecticut and the Columbia, respectively. The {sup 187}Os/{sup 186}Os ratios estimated for the Mississippi and the Vistula are 10.4 and 10.7, respectively. For the Connecticut and the Columbia {sup 187}Os/{sup 186}Os = 8.8 and 14.4, respectively. Of all the rivers examined, the Mississippi is by far the largest, supplying {approximately}1.6% of the total annual world river flow. Its osmium isotopic composition is identical to the upper Mississippi valley loesses indicating (1) congruent dissolution of the bedrock and (2) little or no impact of anthropogenic sources on the osmium isotopic composition of the dissolved load. The latter observation indicates that the upper limit of the anthropogenic input in the dissolved osmium load of the Mississippi outflow is about 250 g yr{sup -1}. While the osmium concentration of the Vistula is high the isotopic composition does not appear to have been affected by substantial pollution. The river data can be used to put limits on the mean residence time of osmium in the oceans ({bar {tau}}{sub Os}) and on the osmium budget of the oceans. 17 refs., 1 fig., 1 tab.

  3. Photovoltaic cells employing zinc phosphide

    DOEpatents

    Barnett, Allen M.; Catalano, Anthony W.; Dalal, Vikram L.; Masi, James V.; Meakin, John D.; Hall, Robert B.

    1984-01-01

    A photovoltaic cell having a zinc phosphide absorber. The zinc phosphide can be a single or multiple crystal slice or a thin polycrystalline film. The cell can be a Schottky barrier, heterojunction or homojunction device. Methods for synthesizing and crystallizing zinc phosphide are disclosed as well as a method for forming thin films.

  4. Osmium Recycling in Subduction Zones

    PubMed

    Brandon; Creaser; Shirey; Carlson

    1996-05-10

    Peridotite xenoliths from the Cascade arc in the United States and in the Japan arc have neodymium and osmium isotopic compositions that are consistent with addition of 5 to 15 percent of subducted material to the present-day depleted mantle. These observations suggest that osmium can be partitioned into oxidized and chlorine-rich slab-derived fluids or melts. These results place new constraints on the behavior of osmium (and possibly other platinum group elements) during subduction of oceanic crust by showing that osmium can be transported into the mantle wedge. PMID:8662577

  5. Solar abundance of osmium

    PubMed Central

    Jacoby, George; Aller, Lawrence H.

    1976-01-01

    The abundance parameter, log gfA, where g is the statistical weight of the lower level, f is the oscillator strength, and A is the abundance (by numbers of atoms with respect to hydrogen), has been derived for three lines of osmium by a method of spectrum synthesis. An apparent discordance of the derived abundance with that found from the carbonaceous chondrites is probably to be attributed primarily to errors in the f-values, and blending with unknown contributors. PMID:16592314

  6. Fatal aluminium phosphide poisoning

    PubMed Central

    Mittal, Sachin; Rani, Yashoda

    2015-01-01

    Aluminium phosphide (AlP) is a cheap solid fumigant and a highly toxic pesticide which is commonly used for grain preservation. AlP has currently aroused interest with a rising number of cases in the past four decades due to increased use for agricultural and non-agricultural purposes. Its easy availability in the markets has increased also its misuse for committing suicide. Phosphine inhibits cellular oxygen utilization and can induce lipid peroxidation. Poisoning with AlP has often occurred in attempts to commit suicide, and that more often in adults than in teenagers. This is a case of suicidal consumption of aluminium phosphide by a 32-year-old young medical anesthetist. Toxicological analyses detected aluminium phosphide. We believe that free access of celphos tablets in grain markets should be prohibited by law. PMID:27486362

  7. Zinc Phosphide Poisoning

    PubMed Central

    Doğan, Erdal; Güzel, Abdulmenap; Çiftçi, Taner; Aycan, İlker; Çetin, Bedri; Kavak, Gönül Ölmez

    2014-01-01

    Zinc phosphide has been used widely as a rodenticide. Upon ingestion, it gets converted to phosphine gas in the body, which is subsequently absorbed into the bloodstream through the stomach and the intestines and gets captured by the liver and the lungs. Phosphine gas produces various metabolic and nonmetabolic toxic effects. Clinical symptoms are circulatory collapse, hypotension, shock symptoms, myocarditis, pericarditis, acute pulmonary edema, and congestive heart failure. In this case presentation, we aim to present the intensive care process and treatment resistance of a patient who ingested zinc phosphide for suicide purposes. PMID:25101186

  8. Osmium: an appraisal of environmental exposure.

    PubMed

    Smith, I C; Carson, B L; Ferguson, T L

    1974-08-01

    In the U.S., the chief source of new osmium is copper refining, where this metal is produced as a byproduct. Probably less than 10% of the osmium in the original copper ore is recovered, and 1000-3000 oz troy of osmium is lost each year to the environment as the toxic, volatile tetroxide from copper smelters. In 1971, about 2000 oz troy of osmium was domestically refined, most of which was from secondary sources. An additional 4169 oz troy of osmium was toll-refined. Major uses for osmium tetroxide identified are for catalysis, especially in steroid synthesis, and for tissue staining. Minor uses of osmium metal are for electrical contacts and for imparting hardness to alloys for mechanical pivots, etc. Unreclaimed osmium tetroxide that reaches wastewater streams is probably rapidly reduced by organic matter to nontoxic osmium dioxide or osmium metal, which would settle out in the sediment of the water course. Waste osmium metal, itself innocuous and chemically resistant, would be oxidized to the toxic tetroxide if incinerated. Because of the small amounts used and their wide dispersal, the amounts of osmium tetroxide in wastewater and air should pose no hazard to man or the environment. The chief acute toxic effects of osmium tetroxide are well known and include eye and respiratory-tract damage. Few data are available that provide information on possible effects of nonacute exposure resulting from environmental contamination by osmium. However, workers continually exposed to osmium tetroxide vapors (refiners and histologists) and rheumatoid arthritis patients who have received intra-articular injections of osmic acid solutions have shown no apparent damage from exposure to low levels of osmium. PMID:4470919

  9. Osmium: An Appraisal of Environmental Exposure

    PubMed Central

    Smith, Ivan C.; Carson, Bonnie L.; Ferguson, Thomas L.

    1974-01-01

    In the U.S., the chief source of new osmium is copper refining, where this metal is produced as a byproduct. Probably less than 10% of the osmium in the original copper ore is recovered, and 1000–3000 oz troy of osmium is lost each year to the environment as the toxic, volatile tetroxide from copper smelters. In 1971, about 2000 oz troy of osmium was domestically refined, most of which was from secondary sources. An additional 4169 oz troy of osmium was toll-refined. Major uses for osmium tetroxide identified are for catalysis, especially in steroid synthesis, and for tissue staining. Minor uses of osmium metal are for electrical contacts and for imparting hardness to alloys for mechanical pivots, etc. Unreclaimed osmium tetroxide that reaches wastewater streams is probably rapidly reduced by organic matter to nontoxic osmium dioxide or osmium metal, which would settle out in the sediment of the water course. Waste osmium metal, itself innocuous and chemically resistant, would be oxidized to the toxic tetroxide if incinerated. Because of the small amounts used and their wide dispersal, the amounts of osmium tetroxide in wastewater and air should pose no hazard to man or the environment. The chief acute toxic effects of osmium tetroxide are well known and include eye and respiratory-tract damage. Few data are available that provide information on possible effects of nonacute exposure resulting from environmental contamination by osmium. However, workers continually exposed to osmium tetroxide vapors (refiners and histologists) and rheumatoid arthritis patients who have received intra-articular injections of osmic acid solutions have shown no apparent damage from exposure to low levels of osmium. PMID:4470919

  10. Gallium phosphide energy converters

    NASA Technical Reports Server (NTRS)

    Sims, P. E.; DiNetta, Louis C.; DuganCavanagh, K.; Goetz, M. A.

    1996-01-01

    Betavoltaic power supplies based on gallium phosphide can supply long term low-level power with high reliability. Results are presented for GaP devices powered by Ni-63 and tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/cm(exp 2) have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. A small demonstration system has been assembled that generates and stores enough electricity to light up an LED.

  11. Osmium-187/osmium-186 in manganese nodules and the Cretaceous-Tertiary boundary

    SciTech Connect

    Luck, J.M.; Turekian, K.K.

    1983-11-11

    As a result of the radioactive decay of rhenium-187 (4.6 x 10/sup 10/ years) the osmium-187/osmium-186 ratio changes in planetary systems as a function of time and the rhenium-187/osmium-186 ratio. For a value of the rhenium-187/osmium-186 ratio of about 3.2, typical of meteorites and the earth's mantle, the present-day osmium-187/osmium-186 ratio is about 1. The earth's continental crust has an estimated rhenium-187/osmium-186 ratio of about 400, so that for a mean age of the continent of 2 x 10/sup 9/ years, a present-day osmium-187/osmium-186 ratio of about 10 is expected. Marine manganese nodules show values (6 to 8.4) compatible with this expectation if allowance for a 25 percent mantle osmium supply to the oceans is allowed. The Cretaceous-Tertiary boundary iridium-rich layer in the marine section at Stevns Klint, Denmark, yields an osmium-187/osmium-186 ratio of 1.65, and the one in a continental section in the Raton Basin, Colorado, is 1.29. The simplest explanation is that these represent osmium imprints of predominantly meteoritic origin.

  12. Gallium phosphide energy converters

    NASA Technical Reports Server (NTRS)

    Sims, P. E.; Dinetta, L. C.; Goetz, M. A.

    1995-01-01

    Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.

  13. Managing aluminum phosphide poisonings

    PubMed Central

    Gurjar, Mohan; Baronia, Arvind K; Azim, Afzal; Sharma, Kalpana

    2011-01-01

    Aluminum phosphide (AlP) is a cheap, effective and commonly used pesticide. However, unfortunately, it is now one of the most common causes of poisoning among agricultural pesticides. It liberates lethal phosphine gas when it comes in contact either with atmospheric moisture or with hydrochloric acid in the stomach. The mechanism of toxicity includes cellular hypoxia due to the effect on mitochondria, inhibition of cytochrome C oxidase and formation of highly reactive hydroxyl radicals. The signs and symptoms are nonspecific and instantaneous. The toxicity of AlP particularly affects the cardiac and vascular tissues, which manifest as profound and refractory hypotension, congestive heart failure and electrocardiographic abnormalities. The diagnosis of AlP usually depends on clinical suspicion or history, but can be made easily by the simple silver nitrate test on gastric content or on breath. Due to no known specific antidote, management remains primarily supportive care. Early arrival, resuscitation, diagnosis, decrease the exposure of poison (by gastric lavage with KMnO4, coconut oil), intensive monitoring and supportive therapy may result in good outcome. Prompt and adequate cardiovascular support is important and core in the management to attain adequate tissue perfusion, oxygenation and physiologic metabolic milieu compatible with life until the tissue poison levels are reduced and spontaneous circulation is restored. In most of the studies, poor prognostic factors were presence of acidosis and shock. The overall outcome improved in the last decade due to better and advanced intensive care management. PMID:21887030

  14. Managing aluminum phosphide poisonings.

    PubMed

    Gurjar, Mohan; Baronia, Arvind K; Azim, Afzal; Sharma, Kalpana

    2011-07-01

    Aluminum phosphide (AlP) is a cheap, effective and commonly used pesticide. However, unfortunately, it is now one of the most common causes of poisoning among agricultural pesticides. It liberates lethal phosphine gas when it comes in contact either with atmospheric moisture or with hydrochloric acid in the stomach. The mechanism of toxicity includes cellular hypoxia due to the effect on mitochondria, inhibition of cytochrome C oxidase and formation of highly reactive hydroxyl radicals. The signs and symptoms are nonspecific and instantaneous. The toxicity of AlP particularly affects the cardiac and vascular tissues, which manifest as profound and refractory hypotension, congestive heart failure and electrocardiographic abnormalities. The diagnosis of AlP usually depends on clinical suspicion or history, but can be made easily by the simple silver nitrate test on gastric content or on breath. Due to no known specific antidote, management remains primarily supportive care. Early arrival, resuscitation, diagnosis, decrease the exposure of poison (by gastric lavage with KMnO(4), coconut oil), intensive monitoring and supportive therapy may result in good outcome. Prompt and adequate cardiovascular support is important and core in the management to attain adequate tissue perfusion, oxygenation and physiologic metabolic milieu compatible with life until the tissue poison levels are reduced and spontaneous circulation is restored. In most of the studies, poor prognostic factors were presence of acidosis and shock. The overall outcome improved in the last decade due to better and advanced intensive care management. PMID:21887030

  15. Aluminium phosphide-induced leukopenia.

    PubMed

    Ntelios, Dimitrios; Mandros, Charalampos; Potolidis, Evangelos; Fanourgiakis, Panagiotis

    2013-01-01

    Acute intoxication from the pesticide aluminium phosphide is a relatively rare, life-threatening condition in which cardiovascular decompensation is the most feared problem. We report the case of a patient exposed to aluminium phosphide-liberated phosphine gas. It resulted in the development of a gastroenteritis-like syndrome accompanied by severe reduction in white blood cell numbers as an early and prominent manifestation. By affecting important physiological processes such as mitochondrial function and reactive oxygen species homeostasis, phosphine could cause severe toxicity. After presenting the characteristics of certain leucocyte subpopulations we provide the current molecular understanding of the observed leukopenia which in part seems paradoxical. PMID:24172776

  16. Aluminium phosphide-induced leukopenia

    PubMed Central

    Ntelios, Dimitrios; Mandros, Charalampos; Potolidis, Evangelos; Fanourgiakis, Panagiotis

    2013-01-01

    Acute intoxication from the pesticide aluminium phosphide is a relatively rare, life-threatening condition in which cardiovascular decompensation is the most feared problem. We report the case of a patient exposed to aluminium phosphide-liberated phosphine gas. It resulted in the development of a gastroenteritis-like syndrome accompanied by severe reduction in white blood cell numbers as an early and prominent manifestation. By affecting important physiological processes such as mitochondrial function and reactive oxygen species homeostasis, phosphine could cause severe toxicity. After presenting the characteristics of certain leucocyte subpopulations we provide the current molecular understanding of the observed leukopenia which in part seems paradoxical. PMID:24172776

  17. Residence time of osmium in the oceans

    NASA Astrophysics Data System (ADS)

    Oxburgh, Rachel

    2001-06-01

    Estimates of osmium residence time in the oceans that are based on oceanic mass balance calculations (35-50 kyr) appear irreconcilable with those inferred from the recent evolution of the osmium isotope composition of seawater (3-4 kyr). It is argued that the osmium budget of the oceans is currently close to steady state and thus that the estimates made by the two methods should agree. As the inventory of osmium in the oceans is relatively well constrained, these disparate residence time estimates imply wildly different osmium input fluxes to the oceans. An osmium residence time of 8-10 kyr is proposed by evaluating the uncertainties and limitations of both methods, and it is argued that osmium inputs to the ocean are currently underestimated by a factor of ˜3. This reflects in part the underestimation of the river input of osmium to the oceans owing to a bias within the existing data set and in part the probable existence of sources of osmium to the oceans that have not yet been identified. The very short residence time of 3-4 kyr inferred from the postglacial change in seawater composition (assuming a single step change in input flux) is rejected as it implies unreasonably high osmium input fluxes to the oceans. It is concluded that a postglacial spike in osmium flux, associated with a meltwater event, must have driven part of the change in seawater composition. However, it is also shown that such a spike cannot be the dominant cause of the most recent shift in seawater 187Os/188Os.

  18. Phonon properties of americium phosphide

    NASA Astrophysics Data System (ADS)

    Arya, B. S.; Aynyas, Mahendra; Sanyal, S. P.

    2016-05-01

    Phonon properties of AmP have been studied by using breathing shell models (BSM) which includes breathing motion of electrons of the Am atoms due to f-d hybridization. The phonon dispersion curves, specific heat calculated from present model. The calculated phonon dispersion curves of AmP are presented follow the same trend as observed in uranium phosphide. We discuss the significance of this approach in predicting the phonon dispersion curves of these compounds and examine the role of electron-phonon interaction.

  19. Development of anticancer agents: wizardry with osmium.

    PubMed

    Hanif, Muhammad; Babak, Maria V; Hartinger, Christian G

    2014-10-01

    Platinum compounds are one of the pillars of modern cancer chemotherapy. The apparent disadvantages of existing chemotherapeutics have led to the development of novel anticancer agents with alternative modes of action. Many complexes of the heavy metal osmium (Os) are potent growth inhibitors of human cancer cells and are active in vivo, often superior or comparable to cisplatin, as the benchmark metal-based anticancer agent, or clinically tested ruthenium (Ru) drug candidates. Depending on the choice of ligand system, osmium compounds exhibit diverse modes of action, including redox activation, DNA targeting or inhibition of protein kinases. In this review, we highlight recent advances in the development of osmium anticancer drug candidates and discuss their cellular mechanisms of action. PMID:24955838

  20. Can Ni phosphides become viable hydroprocessing catalysts?

    SciTech Connect

    Soled, S.; Miseo, S.; Baumgartner, J.; Guzman, J.; Bolin, T.; Meyer, R.

    2015-05-15

    We prepared higher surface area nickel phosphides than are normally found by reducing nickel phosphate. To do this, we hydrothermally synthesized Ni hydroxy phosphite precursors with low levels of molybdenum substitution. The molybdenum substitution increases the surface area of these precursors. During pretreatment in a sulfiding atmosphere (such as H2S/H2) dispersed islands of MoS2 segregate from the precursor and provide a pathway for H2 dissociation that allows reduction of the phosphite precursor to nickel phosphide at substantially lower temperatures than in the absence of MoS2. The results reported here show that to create nickel phosphides with comparable activity to conventional supported sulfide catalysts, one would have to synthesize the phosphide with surface areas exceeding 400 m2/g (i.e. with nanoparticles less than 30 Å in lateral dimension).

  1. The concentration and isotopic composition of osmium in the oceans

    SciTech Connect

    Sharma, M.; Papanastassiou, D.A.; Wasserburg, G.J.

    1997-08-01

    Osmium is one of the rarer elements in seawater. Analytical difficulties have previously prevented the direct measurement of the osmium concentration and isotopic composition in seawater. We report a chemical separation procedure that yields quantitative extraction of osmium standard and of osmium tracer by iron hydroxide precipitation from seawater doped with osmium standard, osmium tracer, and FeCl{sub 3}. The iron hydroxide precipitate is processed to extract osmium, using techniques developed for iron meteorites. Utilizing this procedure, water samples from the Pacific and Atlantic oceans were analyzed for osmium concentration and isotopic composition. Direct determination of the osmium concentration of seawater gives between 15 and 19 fM kg{sup -1}. Detailed experiments on different aliquots of one seawater sample from the North Atlantic Ocean, keeping the amounts of reagents constant, yield concentrations from 16 to 19 fM kg{sup -1}. The variability in concentration is outside the uncertainty introduced because of blanks and indicates a lack of full equilibration between the osmium tracer and seawater osmium. The most reliable osmium concentration of the North Atlantic deep ocean water is 19 fM kg {sup -1} with the {sup 187}Os/{sup 186}Os ratio being 8.7{+-}2 (2{sigma}). Detailed experiments on one seawater sample from the Central Pacific Ocean indicate that the most reliable osmium concentration of the deep ocean water from the Central Pacific is 19 fM kg{sup -1} with the {sup 187}Os/{sup 186}Os ratio being 8.7{+-}0.3 (2{sigma}). The directly measured osmium isotopic composition of the oceans is in good agreement with that obtained from the analysis of some rapidly accumulating organic rich sediments. A sample of ambient seawater around the Juan de Fuca Ridge gave {sup 187}Os/{sup 186}Os = 6.9{+-} 0.4. 42 refs., 6 figs., 4 tabs.

  2. Osmium-191/iridium-191m radionuclide

    DOEpatents

    Knapp, Jr., Furn F.; Butler, Thomas A.; Brihaye, Claude

    1987-01-01

    A generator system to provide iridium-191m for clinical imaging applications comprises an activated carbon adsorbent loaded with a compound containing the parent nuclide, osmium-191. The generator, which has a shelf-life in excess of two weeks and does not require a scavenger column, can be eluted with physiologically compatible saline.

  3. Osmium-191/iridium-191m radionuclide

    DOEpatents

    Knapp, F.F. Jr.; Butler, T.A.; Brihaye, C.

    1985-08-26

    A generator system to provide iridium-191m for clinical imaging applications comprises an activated carbon adsorbent loaded with a compound containing the parent nuclide, osmium-191. The generator, which has a shelf-life in excess of two weeks and does not require a scavenger column, can be eluted with physiologically compatible saline. 4 figs. 3 tabs.

  4. 40 CFR 180.284 - Zinc phosphide; tolerances for residues.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Zinc phosphide; tolerances for... § 180.284 Zinc phosphide; tolerances for residues. (a) General. Tolerances are established for residues of the phosphine resulting from the use of the rodenticide zinc phosphide in or on the...

  5. 40 CFR 180.284 - Zinc phosphide; tolerances for residues.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Zinc phosphide; tolerances for... § 180.284 Zinc phosphide; tolerances for residues. (a) General. Tolerances are established for residues of the phosphine resulting from the use of the rodenticide zinc phosphide in or on the...

  6. 40 CFR 180.284 - Zinc phosphide; tolerances for residues.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Zinc phosphide; tolerances for... § 180.284 Zinc phosphide; tolerances for residues. (a) General. Tolerances are established for residues of the phosphine resulting from the use of the rodenticide zinc phosphide in or on the...

  7. 40 CFR 180.284 - Zinc phosphide; tolerances for residues.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Zinc phosphide; tolerances for... § 180.284 Zinc phosphide; tolerances for residues. (a) General. Tolerances are established for residues of the phosphine resulting from the use of the rodenticide zinc phosphide in or on the...

  8. Synthesis and controlled growth of osmium nanoparticles by electron irradiation.

    PubMed

    Pitto-Barry, Anaïs; Perdigao, Luis M A; Walker, Marc; Lawrence, James; Costantini, Giovanni; Sadler, Peter J; Barry, Nicolas P E

    2015-12-21

    We have synthesised osmium nanoparticles of defined size (1.5-50 nm) on a B- and S-doped turbostratic graphitic structure by electron-beam irradiation of an organometallic osmium complex encapsulated in self-spreading polymer micelles, and characterised them by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and atomic force microscopy (AFM) on the same grid. Oxidation of the osmium nanoparticles after exposure to air was detected by X-ray photoelectron spectroscopy (XPS). PMID:26418726

  9. Isoelectronic Traps in Gallium Phosphide

    NASA Astrophysics Data System (ADS)

    Christian, Theresa; Alberi, Kirstin; Beaton, Daniel; Fluegel, Brian; Mascarenhas, Angelo

    2015-03-01

    Isoelectronic substitutional dopants can result in strongly localized exciton traps within a host bandstructure such as gallium arsenide (GaAs) or gallium phosphide (GaP). These traps have received great attention for their role in the anomalous bandgap bowing of nitrogen or bismuth-doped GaAs, creating the dramatic bandgap tunability of these unusual dilute alloys. In the wider, indirect-bandgap host material GaP, these same isoelectronic dopants create bound states within the gap that can have very high radiative efficiency and a wealth of discrete spectral transitions illuminating the symmetry of the localized excitonic trap state. We will present a comparative study of nitrogen and bismuth isoelectronic traps in GaP. Research was supported by the U. S. Department of Energy, Basic Energy Sciences, Materials Sciences and Engineering Division under contract DE-AC36-08GO28308 and by the Department of Energy Office of Science Graduate Fellowship Program (DOE SCGF), made possible in part by the American Recovery and Reinvestment Act of 2009, administered by ORISE-ORAU under contract no. DE-AC05-06OR23100.

  10. Transition Metal Phosphide Hydroprocessing Catalysts: A review

    SciTech Connect

    Oyama, S.; Gott, T; Zhao, H; Lee, Y

    2009-01-01

    The diminishing quality of oil feedstocks coupled with increasingly more stringent environmental regulations limiting the content of sulfur in transportation fuels have given rise to a need for improved hydroprocessing technology. This review begins with a summary of the major improvements in hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) catalysts and processes that have been reported in recent years. It then describes a new class of hydroprocessing catalysts, the transition metal phosphides, which have emerged as a promising group of high-activity, stable catalysts. The phosphides have physical properties resembling ceramics, so are strong and hard, yet retain electronic and magnetic properties similar to metals. Their crystal structures are based on trigonal prisms, yet they do not form layered structures like the sulfides. They display excellent performance in HDS and HDN, with the most active phosphide, Ni{sub 2}P, having activity surpassing that of promoted sulfides on the basis of sites titrated by chemisorption (CO for the phosphides, O{sub 2} for the sulfides). In the HDS of difficult heteroaromatics like 4,6-dimethyldibenzothiophene Ni{sub 2}P operates by the hydrogenation pathway, while in the HDN of substituted nitrogen compounds like 2-methylpiperidine it carries out nucleophilic substitution. The active sites for hydrogenation in Ni{sub 2}P have a square pyramidal geometry, while those for direct hydrodesulfurization have a tetrahedral geometry. Overall, Ni{sub 2}P is a promising catalyst for deep HDS in the presence of nitrogen and aromatic compounds.

  11. Sinterless Formation Of Contacts On Indium Phosphide

    NASA Technical Reports Server (NTRS)

    Weizer, Victor G.; Fatemi, Navid S.

    1995-01-01

    Improved technique makes it possible to form low-resistivity {nearly equal to 10(Sup-6) ohm cm(Sup2)} electrical contacts on indium phosphide semiconductor devices without damaging devices. Layer of AgP2 40 Angstrom thick deposited on InP before depositing metal contact. AgP2 interlayer sharply reduces contact resistance, without need for sintering.

  12. Development of gallium aluminum phosphide electroluminescent diodes

    NASA Technical Reports Server (NTRS)

    Chicotka, R. J.; Lorenz, M. R.; Nethercot, A. H.; Pettit, G. D.

    1972-01-01

    Work done on the development of gallium aluminum phosphide alloys for electroluminescent light sources is described. The preparation of this wide band gap semiconductor alloy, its physical properties (particularly the band structure, the electrical characteristics, and the light emitting properties) and work done on the fabrication of diode structures from these alloys are broadly covered.

  13. InP (Indium Phosphide): Into the future

    NASA Technical Reports Server (NTRS)

    Brandhorst, Henry W., Jr.

    1989-01-01

    Major industry is beginning to be devoted to indium phosphide and its potential applications. Key to these applications are high speed and radiation tolerance; however the high cost of indium phosphide may be an inhibitor to progress. The broad applicability of indium phosphide to many devices will be discussed with an emphasis on photovoltaics. Major attention is devoted to radiation tolerance and means of reducing cost of devices. Some of the approaches applicable to solar cells may also be relevant to other devices. The intent is to display the impact of visionary leadership in the field and enable the directions and broad applicability of indium phosphide.

  14. Efficient water reduction with gallium phosphide nanowires

    PubMed Central

    Standing, Anthony; Assali, Simone; Gao, Lu; Verheijen, Marcel A.; van Dam, Dick; Cui, Yingchao; Notten, Peter H. L.; Haverkort, Jos E. M.; Bakkers, Erik P. A. M.

    2015-01-01

    Photoelectrochemical hydrogen production from solar energy and water offers a clean and sustainable fuel option for the future. Planar III/V material systems have shown the highest efficiencies, but are expensive. By moving to the nanowire regime the demand on material quantity is reduced, and new materials can be uncovered, such as wurtzite gallium phosphide, featuring a direct bandgap. This is one of the few materials combining large solar light absorption and (close to) ideal band-edge positions for full water splitting. Here we report the photoelectrochemical reduction of water, on a p-type wurtzite gallium phosphide nanowire photocathode. By modifying geometry to reduce electrical resistance and enhance optical absorption, and modifying the surface with a multistep platinum deposition, high current densities and open circuit potentials were achieved. Our results demonstrate the capabilities of this material, even when used in such low quantities, as in nanowires. PMID:26183949

  15. Efficient water reduction with gallium phosphide nanowires

    NASA Astrophysics Data System (ADS)

    Standing, Anthony; Assali, Simone; Gao, Lu; Verheijen, Marcel A.; van Dam, Dick; Cui, Yingchao; Notten, Peter H. L.; Haverkort, Jos E. M.; Bakkers, Erik P. A. M.

    2015-07-01

    Photoelectrochemical hydrogen production from solar energy and water offers a clean and sustainable fuel option for the future. Planar III/V material systems have shown the highest efficiencies, but are expensive. By moving to the nanowire regime the demand on material quantity is reduced, and new materials can be uncovered, such as wurtzite gallium phosphide, featuring a direct bandgap. This is one of the few materials combining large solar light absorption and (close to) ideal band-edge positions for full water splitting. Here we report the photoelectrochemical reduction of water, on a p-type wurtzite gallium phosphide nanowire photocathode. By modifying geometry to reduce electrical resistance and enhance optical absorption, and modifying the surface with a multistep platinum deposition, high current densities and open circuit potentials were achieved. Our results demonstrate the capabilities of this material, even when used in such low quantities, as in nanowires.

  16. Anthropogenic forcings on the surficial osmium cycle.

    PubMed

    Rauch, Sebastien; Peucker-Ehrenbrink, Bernhard; Kylander, Malin E; Weiss, Dominik J; Martinez-Cortizas, Antonio; Heslop, David; Olid, Carolina; Mighall, Tim M; Hemond, Harold F

    2010-02-01

    Osmium is among the least abundant elements in the Earth's continental crust. Recent anthropogenic Os contamination of the environment from mining and smelting activities, automotive catalytic converter use, and hospital discharges has been documented. Here we present evidence for anthropogenic overprinting of the natural Os cycle using a ca. 7000-year record of atmospheric Os deposition and isotopic composition from an ombrotrophic peat bog in NW Spain. Preanthropogenic Os accumulation in this area is 0.10 +/- 0.04 ng m(-2) y(-1). The oldest strata showing human influence correspond to early metal mining and processing on the Iberian Peninsula (ca. 4700-2500 cal. BP). Elevated Os accumulation rates are found thereafter with a local maximum of 1.1 ng m(-2) y(-1) during the Roman occupation of the Iberian Peninsula (ca. 1930 cal. BP) and a further increase starting in 1750 AD with Os accumulation reaching 30 ng m(-2) y(-1) in the most recent samples. Osmium isotopic composition ((187)Os/(188)Os) indicates that recent elevated Os accumulation results from increased input of unradiogenic Os from industrial and automotive sources as well as from enhanced deposition of radiogenic Os through increased fossil fuel combustion and soil erosion. We posit that the rapid increase in catalyst-equipped vehicles, increased fossil fuel combustion, and changes in land-use make the changes observed in NW Spain globally relevant. PMID:19995091

  17. Aluminum phosphide poisoning: an unsolved riddle.

    PubMed

    Anand, R; Binukumar, B K; Gill, Kiran Dip

    2011-08-01

    Aluminum phosphide (ALP), a widely used insecticide and rodenticide, is also infamous for the mortality and morbidity it causes in ALP-poisoned individuals. The toxicity of metal phosphides is due to phosphine liberated when ingested phosphides come into contact with gut fluids. ALP poisoning is lethal, having a mortality rate in excess of 70%. Circulatory failure and severe hypotension are common features of ALP poisoning and frequent cause of death. Severe poisoning also has the potential to induce multi-organ failure. The exact site or mechanism of its action has not been proved in humans. Rather than targeting a single organ to cause gross damage, ALP seems to work at the cellular level, resulting in widespread damage leading to multiorgan dysfunction (MOD) and death. There has been proof in vitro that phosphine inhibits cytochrome c oxidase. However, it is unlikely that this interaction is the primary cause of its toxicity. Mitochondria could be the possible site of maximum damage in ALP poisoning, resulting in low ATP production followed by metabolic shutdown and MOD; also, owing to impairment in electron flow, there could be free radical generation and damage, again producing MOD. Evidence of reactive oxygen species-induced toxicity owing to ALP has been observed in insects and rats. A similar mechanism could also play a role in humans and contribute to the missing link in the pathogenesis of ALP toxicity. There is no specific antidote for ALP poisoning and supportive measures are all that are currently available. PMID:21607993

  18. Microwave-assisted synthesis of transition metal phosphide

    SciTech Connect

    Viswanathan, Tito

    2014-12-30

    A method of synthesizing transition metal phosphide. In one embodiment, the method has the steps of preparing a transition metal lignosulfonate, mixing the transition metal lignosulfonate with phosphoric acid to form a mixture, and subjecting the mixture to a microwave radiation for a duration of time effective to obtain a transition metal phosphide.

  19. SINGLE-LABORATORY EVALUATION OF OSMIUM ANALYTICAL METHODS

    EPA Science Inventory

    The results of a single-laboratory study of osmium analytical methods are described. The methods studied include direct-aspiration atomic absorption spectroscopy (EPA Method 7550), furnace atomic absorption spectroscopy and inductively coupled plasma atomic emission spectroscopy ...

  20. Anthropogenic Osmium in Airborne Particles from Woods Hole, Massachusetts, USA

    NASA Astrophysics Data System (ADS)

    Peucker-Ehrenbrink, B.; Sen, I. S.; Geboy, N.

    2012-12-01

    The global geochemical cycle of osmium has been significantly disturbed by the introduction of automobile exhaust catalysts to convert noxious gas emissions into more benign forms. Anthropogenic osmium has been reported in rainwater, snow, and in the urban airborne particles from around the world to reveal global-scale osmium pollution [1, 2]. In this study, we report on the platinum group element (PGE) concentrations and osmium isotope ratios of airborne particles (PM10) collected in Woods Hole, a small coastal town in Massachusetts to better understand inputs of anthropogenic osmium to rural environments. We further investigate the use of osmium isotopes to track sources of airborne particles and support source apportionment studies on a continental scale. The samples used in this study were collected at Woods Hole Oceanographic Institution over one year (2008-2009). From this collection twelve samples for which the backward air mass trajectories have been determined were selected for osmium isotope analyses. Our results show that the osmium and platinum concentrations are an order of magnitude lower when compared to downtown Boston [2]. The average Os, Pt and Ir concentrations are 0.006±0.012, 0.019±0.023, and 0.685±0.634 pg m-3, respectively. The 187Os/188Os of the aerosols range from 0.275 to 0.788. As continental crust is radiogenic (187Os/188Os >1) and PGE ore bodies generally have unradiogenic 187Os/188Os (~0.2), the unradiogenic 187Os/188Os signature of the aerosols indicates anthropogenic contributions. With 95% of the total osmium mobilization on land being attributed to human activities [3], it is clear that human imprint on airborne particles is not restricted to urban centers with high traffic flows, but also affects rural environments. Aerosol particles that have backward air mass trajectories from the Southwest, the densely populated and industrialized Eastern seaboard, are characterized by unradiogenic osmium, while air masses from the North

  1. Stability and bonding of new superalkali phosphide species.

    PubMed

    Cochran, Elizabeth; Muller, Giel; Meloni, Giovanni

    2015-09-01

    New superalkali phosphide species with the molecular formulas F2Li3P, F2Li3P2, and F4Li6P were investigated. Using the CBS-QB3 composite method to optimize geometry and energetic parameters, four monophosphides, two diphosphides, and one disuperalkali phosphide were discovered that contain intriguing structural features, including hyperlithiation, phosphorus-phosphorus bonds, and planar tetracoordinated phosphorus. It is believed that these features lend to the stability of these structures and may warrant further experimental investigation of these phosphide species to determine if they could play some role in the development of novel chemical reactions and/or materials. PMID:26219751

  2. A systematic review of aluminium phosphide poisoning.

    PubMed

    Mehrpour, Omid; Jafarzadeh, Mostafa; Abdollahi, Mohammad

    2012-03-01

    Every year, about 300,000 people die because of pesticide poisoning worldwide. The most common pesticide agents are organophosphates and phosphides, aluminium phosphide (AlP) in particular. AlP is known as a suicide poison that can easily be bought and has no effective antidote. Its toxicity results from the release of phosphine gas as the tablet gets into contact with moisture. Phosphine gas primarily affects the heart, lungs, gastrointestinal tract, and kidneys. Poisoning signs and symptoms include nausea, vomiting, restlessness, abdominal pain, palpitation, refractory shock, cardiac arrhythmias, pulmonary oedema, dyspnoea, cyanosis, and sensory alterations. Diagnosis is based on clinical suspicion, positive silver nitrate paper test to phosphine, and gastric aspirate and viscera biochemistry. Treatment includes early gastric lavage with potassium permanganate or a combination with coconut oil and sodium bicarbonate, administration of charcoal, and palliative care. Specific therapy includes intravenous magnesium sulphate and oral coconut oil. Moreover, acidosis can be treated with early intravenous administration of sodium bicarbonate, cardiogenic shock with fluid, vasopresor, and refractory cardiogenic shock with intra-aortic baloon pump or digoxin. Trimetazidine may also have a useful role in the treatment, because it can stop ventricular ectopic beats and bigeminy and preserve oxidative metabolism. This article reviews the epidemiological, toxicological, and clinical/pathological aspects of AlP poisoning and its management. PMID:22450207

  3. Osmium coated diffraction grating in the Space Shuttle environment - Performance

    NASA Technical Reports Server (NTRS)

    Torr, M. R.

    1985-01-01

    Samples coated with osmium were flown on the early Shuttle test flights, and on the return of these samples, the osmium coating was found to have disappeared, evidently due to the oxidation of the material in the atomic oxygen atmosphere. An instrument flown on the Spacelab 1 mission comprised an array of five spectrometers covering the extreme ultraviolet (EUV) to near-IR wavelengths. The EUV spectrometer contained an osmium-coated reflective grating located fairly deep within the instruments. Here, results of an assessment of the reflectivity and stability of the osmium surface over the course of the ten-day mission are reported. It is concluded that the osmium reflective coating remained stable relative to the spectrometer coated with MgF2 over the course of the mission. In addition, the ratio of sensitivity of these two spectrometers did not change in any major way from the time of the laboratory calibration until the time of flight two years later. Any changes are within the 50-percent calibration uncertainty.

  4. Doping of indium phosphide with group IV elements

    SciTech Connect

    Zakharenkov, L.F.; Samorukov, B.E.; Zykov, A.M.

    1985-06-01

    This paper studies the doping of single crystals of indium phosphide (InP) with group IV elements using data obtained by measuring the total charge concentration of additives and carriers. Single crystals of indium phosphide were grown by the Czochralski method from liquid melts with a liquid hermetic seal in quartz cubicles. The total impurity concentration was determined by atomic-absorption analysis with + or - 10% error. In order to explain the behavior of germanium and tin in indium phosphide, the authors consider the bond energies of additives in indium phosphide and their tetrahedral radii. The authors conclude that the established higher amphoteric character of germanium with respect to tin is probably explained by the moduli of elasticity of the doped crystal.

  5. Thin boron phosphide coating as a corrosion-resistant layer

    DOEpatents

    Not Available

    1982-08-25

    A surface prone to corrosion in corrosive environments is rendered anticorrosive by CVD growing a thin continuous film, e.g., having no detectable pinholes, thereon, of boron phosphide. In one embodiment, the film is semiconductive. In another aspect, the invention is an improved photoanode, and/or photoelectrochemical cell with a photoanode having a thin film of boron phosphide thereon rendering it anticorrosive, and providing it with unexpectedly improved photoresponsive properties.

  6. BP: synthesis and properties of boron phosphide

    NASA Astrophysics Data System (ADS)

    Woo, Katherine; Lee, Kathleen; Kovnir, Kirill

    2016-07-01

    Cubic boron phosphide, BP, is notorious for its difficult synthesis, thus preventing it from being a widely used material in spite of having numerous favorable technological properties. In the current work, three different methods of synthesis are developed and compared: from the high temperature reaction of elements, Sn flux assisted synthesis, and a solid state metathesis reaction. Structural and optical properties of the products synthesized from the three methods were thoroughly characterized. Solid state metathesis is shown to be the cleanest and most efficient method in terms of reaction temperature and time. Synthesis by Sn flux resulted in a novel Sn-doped BP compound. Undoped BP samples exhibit an optical bandgap of ∼2.2 eV while Sn-doped BP exhibits a significantly smaller bandgap of 1.74 eV. All synthesized samples show high stability in concentrated hydrochloric acid, saturated sodium hydroxide solutions, and fresh aqua regia.

  7. Cavity optomechanics in gallium phosphide microdisks

    NASA Astrophysics Data System (ADS)

    Mitchell, Matthew; Hryciw, Aaron C.; Barclay, Paul E.

    2014-04-01

    We demonstrate gallium phosphide (GaP) microdisk optical cavities with intrinsic quality factors >2.8 × 105 and mode volumes <10(λ/n)3, and study their nonlinear and optomechanical properties. For optical intensities up to 8.0 × 104 intracavity photons, we observe optical loss in the microcavity to decrease with increasing intensity, indicating that saturable absorption sites are present in the GaP material, and that two-photon absorption is not significant. We observe optomechanical coupling between optical modes of the microdisk around 1.5 μm and several mechanical resonances, and measure an optical spring effect consistent with a theoretically predicted optomechanical coupling rate g0/2π˜30 kHz for the fundamental mechanical radial breathing mode at 488 MHz.

  8. Cavity optomechanics in gallium phosphide microdisks

    SciTech Connect

    Mitchell, Matthew; Barclay, Paul E.; Hryciw, Aaron C.

    2014-04-07

    We demonstrate gallium phosphide (GaP) microdisk optical cavities with intrinsic quality factors >2.8 × 10{sup 5} and mode volumes <10(λ/n){sup 3}, and study their nonlinear and optomechanical properties. For optical intensities up to 8.0 × 10{sup 4} intracavity photons, we observe optical loss in the microcavity to decrease with increasing intensity, indicating that saturable absorption sites are present in the GaP material, and that two-photon absorption is not significant. We observe optomechanical coupling between optical modes of the microdisk around 1.5 μm and several mechanical resonances, and measure an optical spring effect consistent with a theoretically predicted optomechanical coupling rate g{sub 0}/2π∼30 kHz for the fundamental mechanical radial breathing mode at 488 MHz.

  9. Direct Band Gap Wurtzite Gallium Phosphide Nanowires

    PubMed Central

    2013-01-01

    The main challenge for light-emitting diodes is to increase the efficiency in the green part of the spectrum. Gallium phosphide (GaP) with the normal cubic crystal structure has an indirect band gap, which severely limits the green emission efficiency. Band structure calculations have predicted a direct band gap for wurtzite GaP. Here, we report the fabrication of GaP nanowires with pure hexagonal crystal structure and demonstrate the direct nature of the band gap. We observe strong photoluminescence at a wavelength of 594 nm with short lifetime, typical for a direct band gap. Furthermore, by incorporation of aluminum or arsenic in the GaP nanowires, the emitted wavelength is tuned across an important range of the visible light spectrum (555–690 nm). This approach of crystal structure engineering enables new pathways to tailor materials properties enhancing the functionality. PMID:23464761

  10. Successful management of zinc phosphide poisoning.

    PubMed

    Shakoori, Vahid; Agahi, Mahsa; Vasheghani-Farahani, Maryam; Marashi, Sayed Mahdi

    2016-06-01

    Zinc phosphide (Zn2P3) rodenticide, is generally misused intentionally for suicidal purpose in Iran. For many years, scientists believe that liberation of phosphine (PH3) on contact with acidic content of the stomach is responsible for clinical presentations. However, relatively long time interval between ingestion of Zn2P3 and presentation of its systemic toxicity, and progression of acute liver failure could not be explained by the current opinion. Hence, an innovative theory intended that phosphonium, as an intermediate product will create and pass through the stomach, which then will reduce to produce PH3in the luminal tract. Here, we present a case of massive Zn2P3 poisoning. In our case, we used repeated doses of castor oil to induce bowel movement with an aim of removing unabsorbed toxin, which was proved by radiography. Interestingly, the patient presents only mild symptoms of toxicity such as transient metabolic acidosis and hepatic dysfunction. PMID:27390464

  11. Successful management of zinc phosphide poisoning

    PubMed Central

    Shakoori, Vahid; Agahi, Mahsa; Vasheghani-Farahani, Maryam; Marashi, Sayed Mahdi

    2016-01-01

    Zinc phosphide (Zn2P3) rodenticide, is generally misused intentionally for suicidal purpose in Iran. For many years, scientists believe that liberation of phosphine (PH3) on contact with acidic content of the stomach is responsible for clinical presentations. However, relatively long time interval between ingestion of Zn2P3 and presentation of its systemic toxicity, and progression of acute liver failure could not be explained by the current opinion. Hence, an innovative theory intended that phosphonium, as an intermediate product will create and pass through the stomach, which then will reduce to produce PH3in the luminal tract. Here, we present a case of massive Zn2P3 poisoning. In our case, we used repeated doses of castor oil to induce bowel movement with an aim of removing unabsorbed toxin, which was proved by radiography. Interestingly, the patient presents only mild symptoms of toxicity such as transient metabolic acidosis and hepatic dysfunction. PMID:27390464

  12. Ab initio melting curve of osmium

    NASA Astrophysics Data System (ADS)

    Burakovsky, L.; Burakovsky, N.; Preston, D. L.

    2015-11-01

    The melting curve of osmium up to a pressure P of 500 GPa is obtained from an extensive suite of ab initio quantum molecular dynamics (QMD) simulations using the Z method. The ab initio P =0 melting point of Os is 3370 ±75 K; this range encompasses all of the available data in the literature and corroborates the conclusion of J. W. Arblaster [Platinum Metals Rev. 49, 166 (2005)], 10.1595/147106705X70264 that the melting temperature of pure Os is 3400 ±50 K and that the 3300 K typically quoted in the literature is the melting point of impure Os. The T =0 equation of state (EOS) of Os and the P dependence of the optimized c /a ratio for the hexagonal unit cell, both to pressures ˜900 GPa, are obtained in the ab initio approach as validation of its use. Although excellent agreement with the available experimental data (P ≲80 GPa) is found, it is the third-order Birch-Murnaghan EOS with B0'=5 rather than the more widely accepted B0'=4 that describes the QMD data to higher pressures, in agreement with the more recent experimental EOS by Godwal et al. The theoretical melting curve of Os obtained earlier by Joshi et al. is shown to be inconsistent with our QMD results, and the possible reason for this discrepancy is suggested. Regularities in the melting curves of Os and five other third-row transition metals (Ta, W, Re, Pt, Au) could be used to estimate the currently unknown melting curves of Hf and Ir.

  13. Method for production of free-standing polycrystalline boron phosphide film

    DOEpatents

    Baughman, Richard J.; Ginley, David S.

    1985-01-01

    A process for producing a free-standing polycrystalline boron phosphide film comprises growing a film of boron phosphide in a vertical growth apparatus on a metal substrate. The metal substrate has a coefficient of thermal expansion sufficiently different from that of boron phosphide that the film separates cleanly from the substrate upon cooling thereof, and the substrate is preferably titanium. The invention also comprises a free-standing polycrystalline boron phosphide film for use in electronic device fabrication.

  14. Free-standing polycrystalline boron phosphide film and method for production thereof

    DOEpatents

    Baughman, R.J.; Ginley, D.S.

    1982-09-09

    A process for producing a free-standing polycrystalline boron phosphide film comprises growing a film of boron phosphide in a vertical growth apparatus on a metal substrate. The metal substrate has a coefficient of thermal expansion sufficiently different from that of boron phosphide that the film separates cleanly from the substrate upon cooling thereof, and the substrate is preferably titanium. The invention also comprises a free-standing polycrystalline boron phosphide film for use in electronic device fabrication.

  15. Discovery of tantalum, rhenium, osmium, and iridium isotopes

    SciTech Connect

    Robinson, R.; Thoennessen, M.

    2012-09-15

    Currently, thirty-eight tantalum, thirty-eight rhenium, thirty-nine osmium, and thirty-eight iridium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  16. Osmium isotopic tracing of atmospheric emissions from an aluminum smelter

    NASA Astrophysics Data System (ADS)

    Gogot, Julien; Poirier, André; Boullemant, Amiel

    2015-09-01

    We present for the first time the use of osmium isotopic composition as a tracer of atmospheric emissions from an aluminum smelter, where alumina (extracted from bauxite) is reduced through electrolysis into metallic aluminum using carbonaceous anodes. These anodes are consumed in the process; they are made of petroleum coke and pitch and have high Re/Os elementary ratio. Due to the relatively large geological age of their source material, their osmium shows a high content of radiogenic 187Os produced from in situ187Re radioactive decay. The radiogenic isotopic composition (187Os/188Os ∼ 2.5) of atmospheric particulate emissions from this smelter is different from that of other typical anthropogenic osmium sources (that come from ultramafic geological contexts with unradiogenic Os isotopes, e.g., 187Os/188Os < 0.2) and also different from average eroding continental crust 187Os/188Os ratios (ca. 1.2). This study demonstrates the capacity of osmium measurements to monitor particulate matter emissions from the Al-producing industry.

  17. Himalayan uplift and osmium isotopes in oceans and rivers

    SciTech Connect

    Sharma, M.; Wasserburg, G.J.; Hofmann, A.W.; Chakrapani, G.J.

    1999-12-01

    Previous studies have shown that {sup 187}Os/{sup 188}Os in seawater has become increasingly radiogenic over the last 409 Ma in a manner analogous to strontium. This rapid rise in the marine {sup 187}Os/{sup 188}Os over the last 17 Ma has been attributed to an increase in the bulk silicate weathering rates resulting from the rise of the Himalayas and/or selective weathering and erosion of highly radiogenic organic rich ancient sediments. The key test of this hypothesis is the {sup 187}Os/{sup 188}Os and the total osmium concentration of the Himalayan rivers. The authors report the concentration and isotopic composition of osmium in the Ganges, the Brahmaputra, and the Indus rivers. The {sup 187}Os/{sup 188}Os of the Ganges close to its source (at Kaudiyal) is 2.65 and [Os] = 45 fM/kg. A second sample of the lower reaches of the Ganges at Patna gives {sup 187}Os/{sup 188}Os = 1.59 and [Os] = 171 fM/kg. The {sup 187}Os/{sup 188}Os of the Brahmaputra at Guwahati is 1.07 and [Os] = 52 fM/kg. A sample of the Indus (Besham) has a {sup 187}Os/{sup 188}Os of 1.2 and [Os] = 59 fM/kg. The authors infer that the Himalayas do not provide either a high flow of osmium of a highly radiogenic osmium component to the oceans. The overall trend for osmium and strontium could be explained by a regularly increasing input of global continental weathering sources but the Himalayas themselves appear not to be the dominant source.

  18. Successful Management of Aluminium Phosphide Poisoning Resulting in Cardiac Arrest

    PubMed Central

    Hakimoğlu, Sedat; Dikey, İsmail; Sarı, Ali; Kekeç, Leyla; Tuzcu, Kasım; Karcıoğlu, Murat

    2015-01-01

    Aluminum phosphide has high toxicity when it is ingested, and in case of contact with moisture, phosphine gas is released. Aluminum phosphide poisoning causes metabolic acidosis, arrhythmia, acute respiratory distress syndrome and shock, and there is no specific antidote. A 17-year-old male patient was referred to our hospital because of aluminum phosphide poisoning with 1500 mg of aluminum phosphide tablets. The patient’s consciousness was clear but he was somnolent. Vital parameters were as follows: blood pressure: 85/56 mmHg, pulse: 88 beats/min, SpO2: 94%, temperature: 36.4°C. Because of hypotension, noradrenaline and dopamine infusions were started. The patient was intubated because of respiratory distress and loss of consciousness. Severe metabolic acidosis was determined in the arterial blood gas, and metabolic acidosis was corrected by sodium bicarbonate treatment. In addition to supportive therapy of the poisoning, haemodialysis was performed. Cardiac arrest occurred during follow-ups in the intensive care unit, and sinus rhythm was achieved after 10 min of cardiopulmonary resuscitation. The patient was discharged after three sessions of haemodialysis on the ninth day. As a result, haemodialysis contributed to symptomatic treatment of aluminum phosphide poisoning in this case report. PMID:27366514

  19. Successful Management of Aluminium Phosphide Poisoning Resulting in Cardiac Arrest.

    PubMed

    Hakimoğlu, Sedat; Dikey, İsmail; Sarı, Ali; Kekeç, Leyla; Tuzcu, Kasım; Karcıoğlu, Murat

    2015-08-01

    Aluminum phosphide has high toxicity when it is ingested, and in case of contact with moisture, phosphine gas is released. Aluminum phosphide poisoning causes metabolic acidosis, arrhythmia, acute respiratory distress syndrome and shock, and there is no specific antidote. A 17-year-old male patient was referred to our hospital because of aluminum phosphide poisoning with 1500 mg of aluminum phosphide tablets. The patient's consciousness was clear but he was somnolent. Vital parameters were as follows: blood pressure: 85/56 mmHg, pulse: 88 beats/min, SpO2: 94%, temperature: 36.4°C. Because of hypotension, noradrenaline and dopamine infusions were started. The patient was intubated because of respiratory distress and loss of consciousness. Severe metabolic acidosis was determined in the arterial blood gas, and metabolic acidosis was corrected by sodium bicarbonate treatment. In addition to supportive therapy of the poisoning, haemodialysis was performed. Cardiac arrest occurred during follow-ups in the intensive care unit, and sinus rhythm was achieved after 10 min of cardiopulmonary resuscitation. The patient was discharged after three sessions of haemodialysis on the ninth day. As a result, haemodialysis contributed to symptomatic treatment of aluminum phosphide poisoning in this case report. PMID:27366514

  20. Phosphine by bio-corrosion of phosphide-rich iron.

    PubMed

    Glindemann, D; Eismann, F; Bergmann, A; Kuschk, P; Stottmeister, U

    1998-01-01

    Phosphine is a toxic agent and part of the phosphorus cycle. A hitherto unknown formation mechanism for phosphine in the environment was investigated. When iron samples containing iron phosphide were incubated in corrosive aquatic media affected by microbial metabolites, phosphine was liberated and measured by gas chromatography. Iron liberates phosphine especially in anoxic aquatic media under the influence of sulfide and an acidic pH. A phosphine-forming mechanism is suggested: Phosphate, an impurity of iron containing minerals, is reduced abioticly to iron phosphide. When iron is exposed to the environment (e.g. as outdoor equipment, scrap, contamination in iron milled food or as iron meteorites) and corrodes, the iron phosphide present in the iron is suspended in the medium and can hydrolyze to phosphine. Phosphine can accumulate to measurable quantities in anoxic microbial media, accelerating corrosion and preserving the phosphine formed from oxidation. PMID:19005813

  1. Osmium-187 enrichment in some plumes: Evidence for core-mantle interaction?

    USGS Publications Warehouse

    Walker, R.J.; Morgan, J.W.; Horan, M.F.

    1995-01-01

    Calculations with data for asteroidal cores indicate that Earth's outer core may have a rhenium/osmium ratio at least 20 percent greater than that of the chondritic upper mantle, potentially leading to an outer core with an osmium-187/osmium-188 ratio at least 8 percent greater than that of chondrites. Because of the much greater abundance of osmium in the outer core relative to the mantle, even a small addition of metal to a plume ascending from the D??? layer would transfer the enriched isotopic signature to the mixture. Sources of certain plume-derived systems seem to have osmium-187/osmium-188 ratios 5 to 20 percent greater than that for chondrites, consistent with the ascent of a plume from the core-mantle boundary.

  2. Carbon phosphide monolayers with superior carrier mobility.

    PubMed

    Wang, Gaoxue; Pandey, Ravindra; Karna, Shashi P

    2016-04-28

    Two dimensional (2D) materials with a finite band gap and high carrier mobility are sought after materials from both fundamental and technological perspectives. In this paper, we present the results based on the particle swarm optimization method and density functional theory which predict three geometrically different phases of the carbon phosphide (CP) monolayer consisting of sp2 hybridized C atoms and sp3 hybridized P atoms in hexagonal networks. Two of the phases, referred to as α-CP and β-CP with puckered or buckled surfaces are semiconducting with highly anisotropic electronic and mechanical properties. More remarkably, they have the lightest electrons and holes among the known 2D semiconductors, yielding superior carrier mobility. The γ-CP has a distorted hexagonal network and exhibits a semi-metallic behavior with Dirac cones. These theoretical findings suggest that the binary CP monolayer is a yet unexplored 2D material holding great promise for applications in high-performance electronics and optoelectronics. PMID:27067002

  3. Fabrication challenges for indium phosphide microsystems

    NASA Astrophysics Data System (ADS)

    Siwak, N. P.; Fan, X. Z.; Ghodssi, R.

    2015-04-01

    From the inception of III-V microsystems, monolithically integrated device designs have been the motivating drive for this field, bringing together the utility of single-chip microsystems and conventional fabrication techniques. Indium phosphide (InP) has a particular advantage of having a direct bandgap within the low loss telecommunication wavelength (1550 nm) range, able to support passive waveguiding and optical amplification, detection, and generation depending on the exact alloy of In, P, As, Ga, or Al materials. Utilizing epitaxy, one can envision the growth of a substrate that contains all of the components needed to establish a single-chip optical microsystem, containing detectors, sources, waveguides, and mechanical structures. A monolithic InP MEMS system has, to our knowledge, yet to be realized due to the significant difficulties encountered when fabricating the integrated devices. In this paper we present our own research and consolidate findings from other research groups across the world to give deeper insight into the practical aspects of InP monolithic microsystem development: epitaxial growth of InP-based alloys, etching techniques, common MEMS structures realized in InP, and future applications. We pay special attention to shedding light on considerations that must be taken when designing and fabricating a monolithic InP MEMS device.

  4. An update on toxicology of aluminum phosphide

    PubMed Central

    2012-01-01

    Aluminum phosphide (AlP) is a cheap solid fumigant and a highly toxic pesticide which is commonly used for grain preservation. In Iran it is known as the “rice tablet”. AlP has currently aroused interest with increasing number of cases in the past four decades due to increased use in agricultural and non-agricultural purposesand also its easy availability in the markets has increased its misuse to commit suicide. Upon contact with moisture in the environment, AlP undergoes a chemical reaction yielding phosphine gas, which is the active pesticidal component. Phosphine inhibits cellular oxygen utilization and can induce lipid peroxidation. It was reported that AlP has a mortality rate more than 50% of intoxication cases. Poisoning with AlP has usually occurred in attempts to suicide. It is a more common case in adults rather than teen agers. In some eastern countries it is a very common agent with rapid action for suicide. Up to date, there is no effective antidote or treatment for its intoxication. Also, some experimental results suggest that magnesium sulfate, N-acetyl cysteine (NAC), glutathione, vitamin C and E, beta-carotenes, coconut oil and melatonin may play an important role in reducing the oxidative outcomes of phosphine. This article reviews the experimental and clinical features of AlP intoxication and tries to suggest a way to encounter its poisoning. PMID:23351193

  5. A mild reduction phosphidation approach to nanocrystalline GaP

    NASA Astrophysics Data System (ADS)

    Chen, Luyang; Luo, Tao; Huang, Mingxing; Gu, Yunle; Shi, Liang; Qian, Yitai

    2004-12-01

    Nanocrystalline gallium phosphide (GaP) has been prepared through a reduction-phosphidation by using Ga, PCl 3 as gallium and phosphorus sources and metallic sodium as reductant at 350 °C. The XRD pattern can be indexed as cublic GaP with the lattice constant of a=5.446 Å. The TEM image shows particle-like polycrystals and flake-like single crystals. The PL spectrum exhibits one peak at 330 nm for the as-prepared nanocrystalline GaP.

  6. Osmium Isotope Straigraphy of Ferromanganese Crusts

    NASA Astrophysics Data System (ADS)

    Bolz, V.; Levasseur, S.; Frank, M.; Hein, J.; Halliday, A.

    2004-12-01

    To interpret the changes in isotopic compositions recorded in hydrogenetic ferromanganese (Fe-Mn) crusts over time it is essential to calibrate them in terms of time. The 10Be method is only reliable for the first 10 Myr. For older parts of the crusts the Co-constant flux method is used. Both approaches however, will fail to account for any growth hiatus or erosion in the sections older than 10 Ma. Attempts at using Sr isotope stratigraphy failed because of post-depositional exchange. For osmium (Os) isotopes on the other hand, calculations of the rate of post-depositional exchange suggest that long-term records in Fe-Mn crusts are reliable. This would allow the 187Os/188Os profile of any hydrogeneous Fe-Mn crust to be fitted against the 187Os/188Os seawater record established for the last 80 Myr. This stratigraphic method would determine the age of crusts at any depth and identify changes in growth rate, cessation of growth and/or intervals of crust erosion. We tested this hypothesis on the hydrogeneous crust CD29-2 from the Central Pacific Ocean which had been subject to many previous radiogenic isotope studies. CD29-2 is a 105mm thick crust with a growth rate of 2.1mm/Myr, as determined from 10Be/9Be ratios and the Co-constant flux method. This gives a minimum age of 50 Ma for the lowermost portions of the crust. Samples were taken every 2mm through the crust which results in a time-spacing of 1Myr assuming a constant growth. For each sample the 187Os/188Os ratio and the 187Os concentration ([187Os]) were determined by ID-NTIMS. The [187Re] was measured by MC-ICPMS, allowing correction for 187 Re-decay. The corrected 187Os/188Os ratios were compared to the seawater record. Using the Be and Co time scales, the 187Os/188Os curve obtained from the crust shows a distorted version of the established seawater record. A good match is found if three hiatuses are allowed. The first hiatus of 15 Myr is assigned to the period between 13 and 28 Ma, a second one of 3 Myr to

  7. Osmium isotope constraints on Earth's late accretionary history

    USGS Publications Warehouse

    Morgan, J.W.

    1985-01-01

    Osmium isotope measurements reported by Alle??gre and Luck 1,2 indicate that terrestrial osmiridiums evolved in a mantle source region in which the osmium/rhenium ratio falls strictly within the range found in chondrites. This suggests that the highly siderophile elements in the Earth's mantle were introduced by a late influx of chondritic material and are not a result of endogenous processes. I have now examined the available data in more detail and conclude that the inferred Os/Re ratio of the Earth's mantle matches the E group and C3 chondrites, but that C1 and probably C2 chondrites were not major components of the material accreted in the late stages of mantle formation. ?? 1985 Nature Publishing Group.

  8. Migration of rhenium and osmium interstitials in tungsten

    NASA Astrophysics Data System (ADS)

    Suzudo, Tomoaki; Yamaguchi, Masatake; Hasegawa, Akira

    2015-12-01

    Tungsten is expected to be a promising plasma-facing material for future fusion devices, but radiation-induced precipitation (RIP), which leads the material to hardening, is a concern at their practical use. One of the keys to accurate prediction of the emergence of RIP is migration of solute atoms, rhenium and osmium, that are produced by nuclear transmutation through irradiation. We conduct a series of numerical simulations using an atomic kinetic Monte Carlo method and investigate the migration of these solute atoms in the form of tungsten-rhenium and tungsten-osmium mixed dumbbells, considered to be the most efficient "carriers" of the solute atoms. We find that the low rotation energy barrier of these mixed dumbbells leading to three-dimensional migration greatly influences their diffusivities. The result also suggests that, although these dumbbells have three-dimensional motion, one cannot simply reduce their migration behavior to that of vacancy-like spherical objects.

  9. Anticancer Organometallic Osmium(II)-p-cymene Complexes.

    PubMed

    Păunescu, Emilia; Nowak-Sliwinska, Patrycja; Clavel, Catherine M; Scopelliti, Rosario; Griffioen, Arjan W; Dyson, Paul J

    2015-09-01

    Osmium compounds are attracting increasing attention as potential anticancer drugs. In this context, a series of bifunctional organometallic osmium(II)-p-cymene complexes functionalized with alkyl or perfluoroalkyl groups were prepared and screened for their antiproliferative activity. Three compounds from the series display selectivity toward cancer cells, with moderate cytotoxicity observed against human ovarian carcinoma (A2780) cells, whereas no cytotoxicity was observed on non-cancerous human embryonic kidney (HEK-293) cells and human endothelial (ECRF24) cells. Two of these three cancer-cell-selective compounds induce cell death largely via apoptosis and were also found to disrupt vascularization in the chicken embryo chorioallantoic membrane (CAM) model. Based on these promising properties, these compounds have potential clinical applications. PMID:26190176

  10. Carbon phosphide monolayers with superior carrier mobility

    NASA Astrophysics Data System (ADS)

    Wang, Gaoxue; Pandey, Ravindra; Karna, Shashi P.

    2016-04-01

    Two dimensional (2D) materials with a finite band gap and high carrier mobility are sought after materials from both fundamental and technological perspectives. In this paper, we present the results based on the particle swarm optimization method and density functional theory which predict three geometrically different phases of the carbon phosphide (CP) monolayer consisting of sp2 hybridized C atoms and sp3 hybridized P atoms in hexagonal networks. Two of the phases, referred to as α-CP and β-CP with puckered or buckled surfaces are semiconducting with highly anisotropic electronic and mechanical properties. More remarkably, they have the lightest electrons and holes among the known 2D semiconductors, yielding superior carrier mobility. The γ-CP has a distorted hexagonal network and exhibits a semi-metallic behavior with Dirac cones. These theoretical findings suggest that the binary CP monolayer is a yet unexplored 2D material holding great promise for applications in high-performance electronics and optoelectronics.Two dimensional (2D) materials with a finite band gap and high carrier mobility are sought after materials from both fundamental and technological perspectives. In this paper, we present the results based on the particle swarm optimization method and density functional theory which predict three geometrically different phases of the carbon phosphide (CP) monolayer consisting of sp2 hybridized C atoms and sp3 hybridized P atoms in hexagonal networks. Two of the phases, referred to as α-CP and β-CP with puckered or buckled surfaces are semiconducting with highly anisotropic electronic and mechanical properties. More remarkably, they have the lightest electrons and holes among the known 2D semiconductors, yielding superior carrier mobility. The γ-CP has a distorted hexagonal network and exhibits a semi-metallic behavior with Dirac cones. These theoretical findings suggest that the binary CP monolayer is a yet unexplored 2D material holding great

  11. Enzyme Biosensor Based on an Electropolymerized Osmium Redox Polymer

    NASA Astrophysics Data System (ADS)

    Tsujimoto, Masaki; Maruyama, Kenichi; Mishima, Yuji; Motonaka, Junko

    Electrochemical polymerizations of metal complex as electron mediator in aqueous solution have been developed. The metal complexes as electron mediator of biosensor for practical application have a rapid electron transfer rate, a chemical stability, and an accessible manipulation. The electro-polymerized redox polymer relatively decreased the enzyme and catalytic activity, although these could be treated in organic solvent. In this work, the water-soluble osmium complex-modified pyrrole derivatives with long, flexible spacer chain were synthesized. The electro-polymerized redox polymer was generally produced by potential sweep copolymerization (-400 mV -/+1200 mV (vs. Ag|AgCl(sat.KCl))) of water-soluble osmium complex-modified pyrrole monomer and glucose oxidase (GOD) on the top of a Pt electrode in aqueous solution. With the electro-polymerized osmium redox polymer modified electrode, calibration graphs for measurements of glucose and the effect of concomitant compounds, dissolved oxygen and the lifetimes of the sensor were electrochemistry examined, respectively. Under optimal conditions, the response of the sensors was in the concentration ranges of 0.6 mM-100 mM for glucose.

  12. Manganese phosphide thin films and nanorods grown on gallium phosphide and on glass substrates

    NASA Astrophysics Data System (ADS)

    Nateghi, N.; Lambert-Milot, S.; Ménard, D.; Masut, R. A.

    2016-05-01

    We report a simple and fast route to grow ferromagnetic manganese phosphide polycrystalline films and nanorods on GaP and on glass substrates using metalorganic vapor phase deposition. Increasing the growth temperature (≥600 °C) and growth time (≥30 min) results in nucleation of secondary MnP crystals on the primary grains. The secondary crystals grow faster along a specific direction of orthorhombic MnP (c-axis) and form long rods (up to ~10 μm) whose diameters are in the nanoscale (20-100 nm). The nanorods can be easily detached from the glass substrate. The films exhibit ferromagnetic behavior with a range of transition temperatures, depending on the growth conditions.

  13. Solvo-thermal synthesis of crystalline dinickel phosphide

    NASA Astrophysics Data System (ADS)

    Lü, Bo; Bai, Yu-Jun; Feng, Xin; Zhao, Yong-Rui; Yang, Jie; Chi, Jie-Ru

    2004-01-01

    Nanocrystalline dinickel phosphide was synthesized via a solvo-thermal route using PCl 3 and NiCl 2 as precursors, and Na as reductant. The crystals were characterized by X-ray powder diffraction and transmission electronic microscopy. It was shown that the product is pure Ni 2P which crystallizes very well with an average size of about 80 nm.

  14. Isotopic determinations of rhenium and osmium in meteorites by using fusion, distillation and ion-exchange separations

    USGS Publications Warehouse

    Morgan, J.W.; Walker, R.J.

    1989-01-01

    A stable isotope-dilution method using resonance ionization mass spectrometry is suitable for the determination of rhenium and osmium abundances and osmium isotopic composition in carbonaceous chondrites and iron meteorites. The chemical procedure involves sodium peroxide fusion, followed by distillation of osmium from sulfuric acid/hydrogen peroxide and subsequent anion-exchange separation of rhenium from the same solution. ?? 1989.

  15. Methods for the separation of rhenium, osmium and molybdenum applicable to isotope geochemistry

    USGS Publications Warehouse

    Morgan, J.W.; Golightly, D.W.; Dorrzapf, A.F., Jr.

    1991-01-01

    Effective methods are described for the chemical separation of rhenium, osmium and molybdenum. The methods are based on distillation and anion-exchange chromatography, and have been the basis for rhenium-osmium isotope studies of ore deposits and meteorites. Successful anion-exchange separation of osmium requires both recognition and careful control of the osmium species in solution; thus, distillation of osmium tetroxide from a mixture of sulfuric acid and hydrogen peroxide is preferred to anion-exchange. Distribution coefficients measured for perrhenate in sulfuric acid media are sufficiently high (Kd > 500) for rhenium to be directly loaded onto an ion-exchange column from a distillation residue and subsequently eluted with nitric acid. Polymerization of molybdenum species during elution is prevented by use of a solution that is 1M in hydrochloric acid and 1M in sodium chloride. ?? 1991.

  16. 3D Nanoporous Metal Phosphides toward High-Efficiency Electrochemical Hydrogen Production.

    PubMed

    Tan, Yongwen; Wang, Hao; Liu, Pan; Cheng, Chun; Zhu, Fan; Hirata, Akihiko; Chen, Mingwei

    2016-04-01

    Free-standing nanoporous metal phosphides are fabricated by a novel top-down method, by selectively leaching less-stable metal phases from rapidly solidified two-phase metal-phosphorus alloys. The phosphide phases with relatively high electrochemical stability are left as the skeletons of nanoporous structures. The resultant nanoporous phosphides with tunable pore size and porosity show superior catalytic activities toward electrochemical hydrogen production. PMID:26889914

  17. Incompressibility of osmium metal at ultrahigh pressures and temperatures

    SciTech Connect

    Armentrout, Matt M.; Kavner, Abby

    2010-07-23

    Osmium is one of the most incompressible elemental metals, and is used as a matrix material for synthesis of ultrahard materials. To examine the behavior of osmium metal under extreme conditions of high pressure and temperature, we measured the thermal equation of state of osmium metal at pressures up to 50 GPa and temperatures up to 3000 K. X-ray diffraction measurements were conducted in the laser heated diamond anvil cell at GeoSoilEnviroCARS and the High Pressure at the Advanced Photon Source and beamline 12.2.2 at the advanced light source. Ambient temperature data give a zero pressure bulk modulus of 421 (3) GPa with a first pressure derivative fixed at 4. Fitting to a high temperature Birch-Murnaghan equation of state gives a room pressure thermal expansion of 1.51(0.06) x 10{sup -5} K{sup -1} with a first temperature derivative of 4.9(0.7) x 10{sup -9} K{sup -2} and the first temperature derivative of bulk modulus of be dK{sub 0}/dT = -0.055 (0.004). Fitting to a Mie-Grueneisen-Debye equation of state gives a Grueneisen parameter of 2.32 (0.08) with a q of 7.2 (1.4). A comparison of the high pressure, temperature behavior among Re, Pt, Os, shows that Os has the highest bulk modulus and lowest thermal expansion of the three, suggesting that Os-based ultrahard materials may be especially mechanically stable under extreme conditions.

  18. Osmium Metal Studied under High Pressure and Nonhydrostatic Stress

    SciTech Connect

    Weinberger,M.; Tolbert, S.; Kavner, A.

    2008-01-01

    Interest in osmium as an ultra-incompressible material and as an analog for the behavior of iron at high pressure has inspired recent studies of its mechanical properties. We have measured elastic and plastic deformation of Os metal at high pressures using in situ high pressure x-ray diffraction in the radial geometry. We show that Os has the highest yield strength observed for any pure metal, supporting up to 10 GPa at a pressure of 26 GPa. Furthermore, our data indicate changes in the nonhydrostatic apparent c/a ratio and clear lattice preferred orientation effects at pressures above 15 GPa.

  19. Osmium isotope constraints on ore metal recycling in subduction zones

    PubMed

    McInnes; McBride; Evans; Lambert; Andrew

    1999-10-15

    Veined peridotite xenoliths from the mantle beneath the giant Ladolam gold deposit on Lihir Island, Papua New Guinea, are 2 to 800 times more enriched in copper, gold, platinum, and palladium than surrounding depleted arc mantle. Gold ores have osmium isotope compositions similar to those of the underlying subduction-modified mantle peridotite source region, indicating that the primary origin of the metals was the mantle. Because the mantle is relatively depleted in gold, copper, and palladium, tectonic processes that enhance the advective transport and concentration of these fluid soluble metals may be a prerequisite for generating porphyry-epithermal copper-gold deposits. PMID:10521343

  20. A quantitative link between recycling and osmium isotopes.

    PubMed

    Sobolev, Alexander V; Hofmann, Albrecht W; Brügmann, Gerhard; Batanova, Valentina G; Kuzmin, Dmitry V

    2008-07-25

    Recycled subducted ocean crust has been traced by elevated 187Os/188Os in some studies and by high nickel and low manganese contents in others. Here, we show that these tracers are linked for Quaternary lavas of Iceland, strengthening the recycling model. An estimate of the osmium isotopic composition of both the recycled crust and the mantle peridotite implies that Icelandic Quaternary lavas are derived in part from an ancient crustal component with model ages between 1.1 _ 109 and 1.8 _ 109 years and from a peridotitic end-member close to present-day oceanic mantle. PMID:18653885

  1. Histopathological changes in cases of aluminium phosphide poisoning.

    PubMed

    Sinha, U S; Kapoor, A K; Singh, A K; Gupta, A; Mehrotra, Ravi

    2005-04-01

    Of a total of 205 poisoning deaths in our hospital in 2003, 83 cases were due to Aluminium phosphide poisoning and were further analyzed. Most vulnerable age group was 21-40 years and M:F ratio was 2:1. On naked eye examination, almost all the vital organs were found to be congested. On microscopic study, the liver showed central venous congestion, degeneration, haemorrhage, sinusoidal dilation, bile stasis, centrilobular necrosis, Kupffer cell hyperplasia, infiltration by mononuclear cells and fatty change. Microscopy of the lungs revealed alveolar thickening, oedema, dilated capillaries, collapsed alveoli and haemorrhage. In the kidney, changes were degeneration, infiltration, tubular dilation and cloudy swelling. Changes in the brain included congestion and coagulative necrosis and in the stomach, congestion and haemorrhage. Easy availability of this cheap and highly toxic substance was responsible for the sudden spurt of poisoning with aluminium phosphide. PMID:16758658

  2. Determination of series resistance of indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Jain, Raj K.; Weinberg, Irving

    1991-01-01

    The series resistance of a solar cell is an important parameter, which must be minimized to achieve high cell efficiencies. The cell series resistance is affected by the starting material, its design, and processing. The theoretical approach proposed by Jia, et. al., is used to calculate the series resistance of indium phosphide solar cells. It is observed that the theoretical approach does not predict the series resistance correctly in all cases. The analysis was modified to include the use of effective junction ideality factor. The calculated results were compared with the available experimental results on indium phosphide solar cells processed by different techniques. It is found that the use of process dependent junction ideality factor leads to better estimation of series resistance. An accurate comprehensive series resistance model is warranted to give proper feedback for modifying the cell processing from the design state.

  3. Synthesis and Hydrodeoxygenation Properties of Ruthenium Phosphide Catalysts

    SciTech Connect

    Bowker, Richard H.; Smith, Mica C.; Pease, Melissa; Slenkamp, Karla M.; Kovarik, Libor; Bussell, Mark E.

    2011-07-01

    Ru2P/SiO2 and RuP/SiO2 catalysts were prepared by the temperature-programmed reduction (TPR) of uncalcined precursors containing hypophosphite ion (H2PO2-) as the phosphorus source. The Ru2P/SiO2 and RuP/SiO2 catalysts had small average particle sizes (~4 nm) and high CO chemisorption capacities (90-110 umol/g). The Ru phosphide catalysts exhibited similar or higher furan (C4H4O) hydrodeoxygenation (HDO) activities than did a Ru/SiO2 catalyst, and the phosphide catalysts favored C4 hydrocarbon products while the Ru metal catalyst produced primarily C3 hydrocarbons.

  4. Status of indium phosphide solar cell development at Spire

    NASA Technical Reports Server (NTRS)

    Spitzer, M. B.; Keavney, C. J.; Vernon, S. M.

    1987-01-01

    On-going development of indium phosphide solar cells for space applications is presented. The development is being carried out with a view towards both high conversion efficiency and simplicity of manufacture. The cell designs comprise the ion-implanted cell, the indium tin oxide top contact cell, and the epitaxial cell grown by metal organic chemical vapor deposition. Modelling data on the limit to the efficiency are presented and comparison is made to measured performance data.

  5. Heat capacity and absolute entropy of iron phosphides

    SciTech Connect

    Dobrokhotova, Z.V.; Zaitsev, A.I.; Litvina, A.D.

    1994-09-01

    There is little or no data on the thermodynamic properties of iron phosphides despite their importance for several areas of science and technology. The information available is of a qualitative character and is based on assessments of the heat capacity and absolute entropy. In the present work, we measured the heat capacity over the temperature range of 113-873 K using a differential scanning calorimeter (DSC) and calculated the absolute entropy.

  6. Predicting crystal structures ab initio: group 14 nitrides and phosphides.

    PubMed

    Hart, Judy N; Allan, Neil L; Claeyssens, Frederik

    2010-08-14

    Crystal structures are predicted for a range of group 14 nitrides and phosphides with 1 : 1 stoichiometry, following our method of starting from the known structures for a range of binary compounds and looking for trends in the preferred local bonding environments in the optimised structures. We have previously applied this method to predict the structures of carbon nitride and phosphorus carbide. Here, we use a similar approach to predict the structures of silicon and germanium nitrides and phosphides with 1 : 1 stoichiometry. We find that the local bonding environments in the preferred structures for the nitrides are the same as those for the 3 : 4 stoichiometry. For the phosphides, we have found several possible structures with similar energies. Structures containing hypervalent phosphorus must be considered as these are often low in energy, particularly for GeP; these have not been included in previous work. The greater tendency to form hypervalent phosphorus in GeP than SiP can be rationalised by considering the bond enthalpies for the two compositions. PMID:20603659

  7. Indium phosphide nanowires and their applications in optoelectronic devices

    PubMed Central

    Zafar, Fateen

    2016-01-01

    Group IIIA phosphide nanocrystalline semiconductors are of great interest among the important inorganic materials because of their large direct band gaps and fundamental physical properties. Their physical properties are exploited for various potential applications in high-speed digital circuits, microwave and optoelectronic devices. Compared to II–VI and I–VII semiconductors, the IIIA phosphides have a high degree of covalent bonding, a less ionic character and larger exciton diameters. In the present review, the work done on synthesis of III–V indium phosphide (InP) nanowires (NWs) using vapour- and solution-phase approaches has been discussed. Doping and core–shell structure formation of InP NWs and their sensitization using higher band gap semiconductor quantum dots is also reported. In the later section of this review, InP NW-polymer hybrid material is highlighted in view of its application as photodiodes. Lastly, a summary and several different perspectives on the use of InP NWs are discussed. PMID:27118920

  8. Diphacinone and zinc phosphide toxicity in a flock of Peafowl.

    PubMed

    Shivaprasad, H L; Galey, F

    2001-12-01

    Toxicity probably due to a combination of diphacinone and zinc phosphide was diagnosed in a flock of peafowl, in which 35 birds in a flock of 80 died over a span of 10 days without any apparent clinical signs. Chickens and guinea fowl, 30 each on the same premises, were not affected. Plastic tubes containing diphacinone and zinc phosphide were used on the premises to control ground squirrels. Most of the six dead peafowl, which ranged in age from 6 months to 4 years, had an accumulation of serosanguinous fluid in the abdominal cavity, semi-clotted blood over the liver lobes, increased pericardial fluid, and enlarged and pale kidneys. Pellets of diphacinone and zinc phosphide were found in the crop and gizzard contents from most of the birds. Microscopically, most of the birds had mild to moderate centrolobular degeneration of hepatocytes and multifocal degeneration of myofibres in the heart with infiltration by a few mononuclear cells. Acute nephrosis and mucosal oedema in the oesophagus and crop were also observed. Toxicological analysis of the crop and gizzard contents revealed the presence of diphacinone and phosphine gas, and analysis of the crop contents from two birds for heavy metals revealed zinc levels of up to 6600 parts/10 6 . It was suspected that only the peafowl and not the chickens and guinea fowl were affected because peafowl, with their longer necks, were able to reach into the plastic tubes and eat the pellets. PMID:19184953

  9. Recent advances in osmium-catalyzed hydrogenation and dehydrogenation reactions.

    PubMed

    Chelucci, Giorgio; Baldino, Salvatore; Baratta, Walter

    2015-02-17

    CONSPECTUS: A current issue in metal-catalyzed reactions is the search for highly efficient transition-metal complexes affording high productivity and selectivity in a variety of processes. Moreover, there is also a great interest in multitasking catalysts that are able to efficiently promote different organic transformations by careful switching of the reaction parameters, such as temperature, solvent, and cocatalyst. In this context, osmium complexes have shown the ability to catalyze efficiently different types of reactions involving hydrogen, proving at the same time high thermal stability and simple synthesis. In the catalytic reduction of C═X (X = O, N) bonds by both hydrogenation (HY) and transfer hydrogenation (TH) reactions, the most interest has been focused on homogeneous systems based on rhodium, iridium, and in particular ruthenium catalysts, which have proved to catalyze chemo- and stereoselective hydrogenations with remarkable efficiency. By contrast, osmium catalysts have received much less attention because they are considered less active on account of their slower ligand exchange kinetics. Thus, this area remained almost neglected until recent studies refuted these prejudices. The aim of this Account is to highlight the impressive developments achieved over the past few years by our and other groups on the design of new classes of osmium complexes and their applications in homogeneous catalytic reactions involving the hydrogenation of carbon-oxygen and carbon-nitrogen bonds by both HY and TH reactions as well as in alcohol deydrogenation (DHY) reactions. The work described in this Account demonstrates that osmium complexes are emerging as powerful catalysts for asymmetric and non-asymmetric syntheses, showing a remarkably high catalytic activity in HY and TH reactions of ketones, aldehydes, imines, and esters as well in DHY reactions of alcohols. Thus, for instance, the introduction of ligands with an NH function, possibly in combination with a

  10. Indium phosphide space solar cell research: Where we are and where we are going

    NASA Technical Reports Server (NTRS)

    Jain, R. K.; Flood, D. J.; Weinberg, Irving

    1995-01-01

    Indium phosphide is considered to be a strong contender for many photovoltaic space applications because of its radiation resistance and its potential for high efficiency. An overview of recent progress is presented, and possible future research directions for indium phosphide space solar cells are discussed. The topics considered include radiation damage studies and space flight experiments.

  11. Ruthenium or osmium complexes and their uses as catalysts for water oxidation

    DOEpatents

    Corbea, Javier Jesus Concepcion; Chen, Zoufeng; Jurss, Jonah Wesley; Templeton, Joseph L.; Hoertz, Paul; Meyer, Thomas J.

    2016-06-07

    The present invention provides ruthenium or osmium complexes and their uses as a catalyst for catalytic water oxidation. Another aspect of the invention provides an electrode and photo-electrochemical cells for electrolysis of water molecules.

  12. A Terminal Osmium(IV) Nitride: Ammonia Formation and Ambiphilic Reactivity.

    PubMed

    Schendzielorz, Florian S; Finger, Markus; Volkmann, Christian; Würtele, Christian; Schneider, Sven

    2016-09-12

    Low-valent osmium nitrides are discussed as intermediates in nitrogen fixation schemes. However, rational synthetic routes that lead to isolable examples are currently unknown. Here, the synthesis of the square-planar osmium(IV) nitride [OsN(PNP)] (PNP=N(CH2 CH2 P(tBu)2 )2 ) is reported upon reversible deprotonation of osmium(VI) hydride [Os(N)H(PNP)](+) . The Os(IV) complex shows ambiphilic nitride reactivity with SiMe3 Br and PMe3 , respectively. Importantly, the hydrogenolysis with H2 gives ammonia and the polyhydride complex [OsH4 (HPNP)] in 80 % yield. Hence, our results directly demonstrate the role of low-valent osmium nitrides and of heterolytic H2 activation for ammonia synthesis with H2 under basic conditions. PMID:27529412

  13. Ruthenium or osmium complexes and their uses as catalysts for water oxidation

    DOEpatents

    Concepcion Corbea, Javier Jesus; Chen, Zuofeng; Jurss, Jonah Wesley; Templeton, Joseph L; Hoertz, Paul; Meyer, Thomas J

    2014-10-28

    The present invention provides ruthenium or osmium complexes and their uses as a catalyst for catalytic water oxidation. Another aspect of the invention provides an electrode and photo-electrochemical cells for electrolysis of water molecules.

  14. Ruthenium or osmium complexes and their uses as catalysts for water oxidation

    DOEpatents

    Corbea, Javier Jesus Concepcion; Chen, Zuofeng; Jurss, Jonah Wesley; Templeton, Joseph L.; Hoertz, Paul; Meyer, Thomas J.

    2013-09-03

    The present invention provides ruthenium or osmium complexes and their uses as a catalyst for catalytic water oxidation. Another aspect of the invention provides an electrode and photo-electrochemical cells for electrolysis of water molecules.

  15. Cyclometalated Osmium-Amine Electronic Communication through the p-Oligophenylene Wire.

    PubMed

    Shen, Jun-Jian; Shao, Jiang-Yang; Gong, Zhong-Liang; Zhong, Yu-Wu

    2015-11-16

    A series of bis-tridentate cyclometalated osmium complexes with a redox-active triarylamine substituent have been prepared, where the amine substituent is separated from the osmium ion by a p-oligophenylene wire of various lengths. X-ray crystallographic data of complexes 3(PF6) and 4(PF6) with three or four repeating phenyl units between the osmium ion and the amine substituent are presented. These complexes show two consecutive anodic redox couples between +0.1 and +0.9 V vs Ag/AgCl, with the potential splitting in the range of 300-390 mV. A combined experimental and theoretical study suggests that, in the one-electron-oxidized state, the odd electron is delocalized for short congeners and localized on the osmium component for long congeners. The electronic coupling parameter (Vab) was estimated by the Marcus-Hush analysis. The distance dependence plot of ln(Vab) versus the osmium-amine geometrical distance (Rab) gives a negative linear relationship with a decay slope of -0.19 Å(-1), which is slightly steeper with respect to the previously reported ruthenium-amine series with the same molecular wire. DFT calculations with the long-range-corrected UCAM-B3LYP functional gave more reasonable results for the osmium complexes with respect to those with UB3LYP. PMID:26567859

  16. Similar Biological Activities of Two Isostructural Ruthenium and Osmium Complexes

    SciTech Connect

    Maksimoska,J.; Williams, D.; Atilla-Gokcumen, G.; Smalley, K.; Carroll, P.; Webster, R.; Filippakopoulos, P.; Knapp, S.; Herlyn, M.; Meggers, E.

    2008-01-01

    In this study, we probe and verify the concept of designing unreactive bioactive metal complexes, in which the metal possesses a purely structural function, by investigating the consequences of replacing ruthenium in a bioactive half-sandwich kinase inhibitor scaffold by its heavier congener osmium. The two isostructural complexes are compared with respect to their anticancer properties in 1205?Lu melanoma cells, activation of the Wnt signaling pathway, IC50 values against the protein kinases GSK-3? and Pim-1, and binding modes to the protein kinase Pim-1 by protein crystallography. It was found that the two congeners display almost indistinguishable biological activities, which can be explained by their nearly identical three-dimensional structures and their identical mode of action as protein kinase inhibitors. This is a unique example in which the replacement of a metal in an anticancer scaffold by its heavier homologue does not alter its biological activity.

  17. A gallium phosphide high-temperature bipolar junction transistor

    NASA Technical Reports Server (NTRS)

    Zipperian, T. E.; Dawson, L. R.; Chaffin, R. J.

    1981-01-01

    Preliminary results are reported on the development of a high temperature (350 C) gallium phosphide bipolar junction transistor (BJT) for geothermal and other energy applications. This four-layer p(+)n(-)pp(+) structure was formed by liquid phase epitaxy using a supercooling technique to insure uniform nucleation of the thin layers. Magnesium was used as the p-type dopant to avoid excessive out-diffusion into the lightly doped base. By appropriate choice of electrodes, the device may also be driven as an n-channel junction field-effect transistor. The initial design suffers from a series resistance problem which limits the transistor's usefulness at high temperatures.

  18. Hydrogenated microcrystalline silicon electrodes connected by indium phosphide nanowires

    NASA Astrophysics Data System (ADS)

    Kobayashi, Nobuhiko P.; VJ, Logeeswaran; Saif Islam, M.; Li, Xuema; Straznicky, Joseph; Wang, Shih-Yuan; Stanley Williams, R.; Chen, Yong

    2007-09-01

    The authors report the connection of two planar hydrogenated silicon (Si:H) electrodes by intersecting and bridging indium phosphide nanowires (InP NWs). A simple metal-semiconductor-metal photoconductor was used as a test vehicle to measure electrical and optical characteristics of the connected InP NWs. This implementation of III-V compound semiconductor nanowires on Si:H combines the characteristics of a direct bandgap semiconductor with the flexible fabrication processes of non-single-crystal silicon platforms that do not require single-crystal substrates.

  19. Radiation damage in proton irradiated indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Swartz, C. K.; Hart, R. E., Jr.; Yamaguchi, Masafumi

    1986-01-01

    Indium phosphide solar cells exposed to 10 MeV proton irradiations were found to have significantly greater radiation resistance than either GaAs or Si. Performance predictions were obtained for two proton dominated orbits and one in which both protons and electrons were significant cell degradation factors. Array specific power was calculated using lightweight blanket technology, a SEP array structure, and projected cell efficiencies. Results indicate that arrays using fully developed InP cells should out-perform those using GaAs or Si in orbits where radiation is a significant cell degradation factor.

  20. Indium phosphide solar cells for laser power beaming applications

    NASA Technical Reports Server (NTRS)

    Jain, Raj K.; Landis, Geoffrey A.

    1992-01-01

    Lasers can be used to transmit power to photovoltaic cells. Solar cell efficiencies are enhanced significantly under monochromatic light, and therefore a laser beam of proper wavelength could be a very effective source of illumination for a solar array operating at very high efficiencies. This work reviews the modeling studies made on indium phosphide solar cells for such an application. These cells are known to be very radiation resistant and have a potential for high efficiency. Effects of cell series resistance, laser intensity, and temperature on cell performance have been discussed.

  1. Aluminum Phosphide Poisoning-Related Deaths in Tehran, Iran, 2006 to 2013

    PubMed Central

    Etemadi-Aleagha, Afshar; Akhgari, Maryam; Iravani, Fariba Sardari

    2015-01-01

    Abstract Metal phosphides such as aluminum phosphide are potent insecticides. This highly toxic substance is used for rice and other grains protection in Iran. Due to its high toxicity potential and easy availability, it is widely used as a suicide poison. This substance has no effective antidote and the incidence of deaths due to its poisoning is increasing day by day in Iran. The present study was conducted to show the increasing incidence of fatal aluminum phosphide poisoning and its toxicological and forensic aspects in an 8-year study, 2006 to 2013. Autopsy sheets were reviewed and cases with the history of aluminum phosphide poisoning were selected. Toxicological analysis results, demographic and necroscopic examination findings were studied. A total of 51.8% of studied cases were female. Most of the cases were between 10 and 40 years old. The manner of death was self-poisoning in 85% of cases. Morphine, ethanol, and amitriptyline were the most common additional drugs detected in toxicological analysis. The incidence of fatal aluminum phosphide poisoning cases referred for phosphine analysis was 5.22 and 37.02 per million of population of Tehran in 2006 and 2013, respectively. The results of this study showed that in spite of ban and restrictions, there was a dramatic increase in the incidence of fatal aluminum phosphide poisoning in Tehran from 2006 to 2013. Safety alert should be highlighted in training program for all population groups about the toxic effects of aluminum phosphide tablets. PMID:26402837

  2. Aluminum Phosphide Poisoning-Related Deaths in Tehran, Iran, 2006 to 2013.

    PubMed

    Etemadi-Aleagha, Afshar; Akhgari, Maryam; Iravani, Fariba Sardari

    2015-09-01

    Metal phosphides such as aluminum phosphide are potent insecticides. This highly toxic substance is used for rice and other grains protection in Iran. Due to its high toxicity potential and easy availability, it is widely used as a suicide poison. This substance has no effective antidote and the incidence of deaths due to its poisoning is increasing day by day in Iran. The present study was conducted to show the increasing incidence of fatal aluminum phosphide poisoning and its toxicological and forensic aspects in an 8-year study, 2006 to 2013. Autopsy sheets were reviewed and cases with the history of aluminum phosphide poisoning were selected. Toxicological analysis results, demographic and necroscopic examination findings were studied. A total of 51.8% of studied cases were female. Most of the cases were between 10 and 40 years old. The manner of death was self-poisoning in 85% of cases. Morphine, ethanol, and amitriptyline were the most common additional drugs detected in toxicological analysis. The incidence of fatal aluminum phosphide poisoning cases referred for phosphine analysis was 5.22 and 37.02 per million of population of Tehran in 2006 and 2013, respectively. The results of this study showed that in spite of ban and restrictions, there was a dramatic increase in the incidence of fatal aluminum phosphide poisoning in Tehran from 2006 to 2013. Safety alert should be highlighted in training program for all population groups about the toxic effects of aluminum phosphide tablets. PMID:26402837

  3. Recent developments in indium phosphide space solar cell research

    NASA Technical Reports Server (NTRS)

    Brinker, David J.; Weinberg, Irving

    1987-01-01

    Recent developments and progress in indium phosphide solar cell research for space application are reviewed. Indium phosphide homojunction cells were fabricated in both the n + p and p + n configurations with total area efficiencies of 17.9 and 15.9 percent (air mass 0 and 25 C) respectively. Organometallic chemical vapor deposition, liquid phase epitaxy, ion implantation and diffusion techniques were employed in InP cell fabrication. A theoretical model of a radiation tolerant, high efficiency homojunction cell was developed. A realistically attainable AM0 efficiency of 20.5 percent was calculated using this model with emitter and base doping of 6 x 10 to the 17th power and 5 x 10 to the 16th power/cu cm, respectively. Cells of both configurations were irradiated with 1 MeV electrons and 37 MeV protons. For both proton and electron irradiation, the n + p cells are more radiation resistant at higher fluences than the p + n cells. The first flight module of four InP cells was assembled for the Living Plume Shield III satellite.

  4. Recent developments in indium phosphide space solar cell research

    NASA Technical Reports Server (NTRS)

    Brinker, David J.; Weinberg, Irving

    1987-01-01

    Recent developments and progress in indium phosphide solar cell research for space application are reviewed. Indium phosphide homojunction cells were fabricated in both the n+p and p+n configurations with total area efficiencies of 17.9 and 15.9% (air mass 0 and 25 C) respectively. Organometallic chemical vapor deposition, liquid phase epitaxy, ion implantation and diffusion techniques were employed in InP cell fabrication. A theoretical model of a radiation tolerant, high efficiency homojunction cell was developed. A realistically attainable AMO efficiency of 20.5% was calculated using this model with emitter and base doping of 6 x 10 to the 17th power and 5 x 10 the the 16th power/cu cm respectively. Cells of both configurations were irradiated with 1 MeV electrons and 37 MeV protons. For both proton and electron irradiation, the n+p cells are more radiation resistant at higher fluences than the p+n cells. The first flight module of four InP cells was assembled for the Living Plume Shield III satellite.

  5. Optimal design study of high efficiency indium phosphide space solar cells

    NASA Technical Reports Server (NTRS)

    Jain, Raj K.; Flood, Dennis J.

    1990-01-01

    Recently indium phosphide solar cells have achieved beginning of life AMO efficiencies in excess of 19 pct. at 25 C. The high efficiency prospects along with superb radiation tolerance make indium phosphide a leading material for space power requirements. To achieve cost effectiveness, practical cell efficiencies have to be raised to near theoretical limits and thin film indium phosphide cells need to be developed. The optimal design study is described of high efficiency indium phosphide solar cells for space power applications using the PC-1D computer program. It is shown that cells with efficiencies over 22 pct. AMO at 25 C could be fabricated by achieving proper material and process parameters. It is observed that further improvements in cell material and process parameters could lead to experimental cell efficiencies near theoretical limits. The effect of various emitter and base parameters on cell performance was studied.

  6. Earth's Phosphides in Levant and insights into the source of Archean prebiotic phosphorus

    PubMed Central

    Britvin, Sergey N.; Murashko, Michail N.; Vapnik, Yevgeny; Polekhovsky, Yury S.; Krivovichev, Sergey V.

    2015-01-01

    Natural phosphides - the minerals containing phosphorus in a redox state lower than zero – are common constituents of meteorites but virtually unknown on the Earth. Herein we present the first rich occurrence of iron-nickel phosphides of terrestrial origin. Phosphide-bearing rocks are exposed in three localities in the surroundings of the Dead Sea, Levant: in the northern Negev Desert, Israel and Transjordan Plateau, south of Amman, Jordan. Seven minerals from the ternary Fe-Ni-P system have been identified with five of them, NiP2, Ni5P4, Ni2P, FeP and FeP2, previously unknown in nature. The results of the present study could provide a new insight on the terrestrial origin of natural phosphides – the most likely source of reactive prebiotic phosphorus at the times of the early Earth. PMID:25667163

  7. Photoelectrochemical cell having photoanode with thin boron phosphide coating as a corrosion resistant layer

    DOEpatents

    Baughman, Richard J.; Ginley, David S.

    1984-01-01

    A surface prone to corrosion in corrosive environments is rendered anticorrosive by CVD growing a thin continuous film, e.g., having no detectable pinholes, thereon, of boron phosphide. In one embodiment, the film is semiconductive. In another aspect, the invention is an improved photoanode, and/or photoelectrochemical cell with a photoanode having a thin film of boron phosphide thereon rendering it anitcorrosive, and providing it with unexpectedly improved photoresponsive properties.

  8. Surface reactions of molecular and atomic oxygen with carbon phosphide films.

    PubMed

    Gorham, Justin; Torres, Jessica; Wolfe, Glenn; d'Agostino, Alfred; Fairbrother, D Howard

    2005-11-01

    The surface reactions of atomic and molecular oxygen with carbon phosphide films have been studied using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Carbon phosphide films were produced by ion implantation of trimethylphosphine into polyethylene. Atmospheric oxidation of carbon phosphide films was dominated by phosphorus oxidation and generated a carbon-containing phosphate surface film. This oxidized surface layer acted as an effective diffusion barrier, limiting the depth of phosphorus oxidation within the carbon phosphide film to < 3 nm. The effect of atomic oxygen (AO) exposure on this oxidized carbon phosphide layer was subsequently probed in situ using XPS. Initially AO exposure resulted in a loss of carbon atoms from the surface, but increased the surface concentration of phosphorus atoms as well as the degree of phosphorus oxidation. For more prolonged AO exposures, a highly oxidized phosphate surface layer formed that appeared to be inert toward further AO-mediated erosion. By utilizing phosphorus-containing hydrocarbon thin films, the phosphorus oxides produced during exposure to AO were found to desorb at temperatures >500 K under vacuum conditions. Results from this study suggest that carbon phosphide films can be used as AO-resistant surface coatings on polymers. PMID:16853637

  9. Rhenium-osmium isotope systematics of carbonaceous chondrites

    USGS Publications Warehouse

    Walker, R.J.; Morgan, J.W.

    1989-01-01

    Rhenium and osmium concentrations and Os isotopic compositions of eight carbonaceous chondrites, one LL3 ordinary chondrite, and two iron meteorites were determined by resonance ionization mass spectrometry. Iron meteorite 187Re/186Os and 187OS/186Os ratios plot on the previously determined iron meteorite isochron, but most chondrite data plot 1 to 2 percent above this meteorite isochron. This suggests either that irons have significantly younger Re-Os closure ages than chondrites or that chondrites were formed from precursor materials with different chemical histories from the precursors of irons. Some samples of Semarkona (LL3) and Murray (C2M) meteorites plot 4 to 6 percent above the iron meteorite isochron, well above the field delineated by other chondrites. Murray may have lost Re by aqueous leaching during its preterrestrial history. Semarkona could have experienced a similar loss of Re, but only slight aqueous alteration is evident in the meteorite. Therefore, the isotopic composition of Semarkona could reflect assembly of isotopically heterogeneous components subsequent to 4.55 billion years ago or Os isotopic heterogeneities in the primordial solar nebula.

  10. Theoretical survey of the reaction between osmium and acetaldehyde

    NASA Astrophysics Data System (ADS)

    Dai, Guo-Liang; Wang, Chuan-Feng

    2012-05-01

    The mechanism of the reaction of osmium atom with acetaldehyde has been investigated with a DFT approach. All the stationary points are determined at the UB3LYP/ sdd/6-311++G** level of the theory. Both ground and excited state potential energy surfaces are investigated in detail. The present results show that the title reaction start with the formation of a CH3CHO-metal complex followed by C-C, aldehyde C-H, C-O, and methyl C-H activation. These reactions can lead to four different products (HOsCH3 + CO, OsCO + CH4, OsCOCH3 + H, and OsO + C2H4). The minimum energy reaction path is found to involve the spin inversion in the initial reaction step. This potential energy curve-crossing dramatically affects reaction exothermic. The present results may be helpful in understanding the mechanism of the title reaction and further experimental investigation of the reaction.

  11. Osmium isotope stratigraphy of a marine ferromanganese crust

    USGS Publications Warehouse

    Klemm, V.; Levasseur, S.; Frank, M.; Hein, J.R.; Halliday, A.N.

    2005-01-01

    Ferromanganese crusts provide records of long term change in ocean circulation and continental weathering. However, calibrating their age prior to 10 Ma has been entirely based on empirical growth rate models using Co concentrations, which have inherently large uncertainties and fail to detect hiatuses and erosional events. We present a new method for dating these crusts by measuring their osmium (Os) isotope record and matching it to the well-known marine Os isotope evolution of the past 80 Ma. The well-characterised crust CD29-2 from the central Pacific, was believed to define a record of paleooceanographic change from 50 Ma. Previous growth rate estimates based on the Co method are consistent with the new Os isotope stratigraphy but the dating was grossly inaccurate due to long hiatuses that are now detectable. The new chronology shows that it in fact started growing prior to 70 Ma in the late Cretaceous and stopped growing or was eroded between 13.5 and 47 Ma. With this new technique it is now possible to exploit the full potential of the oceanographic and climatic records stored in Fe-Mn crusts. ?? 2005 Elsevier B.V. All rights reserved.

  12. Osmium isotope evidence for a large Late Triassic impact event.

    PubMed

    Sato, Honami; Onoue, Tetsuji; Nozaki, Tatsuo; Suzuki, Katsuhiko

    2013-01-01

    Anomalously high platinum group element concentrations have previously been reported for Upper Triassic deep-sea sediments, which are interpreted to be derived from an extraterrestrial impact event. Here we report the osmium (Os) isotope fingerprint of an extraterrestrial impact from Upper Triassic chert successions in Japan. Os isotope data exhibit a marked negative excursion from an initial Os isotope ratio ((187)Os/(188)Osi) of ~0.477 to unradiogenic values of ~0.126 in a platinum group element-enriched claystone layer, indicating the input of meteorite-derived Os into the sediments. The timing of the Os isotope excursion coincides with both elevated Os concentrations and low Re/Os ratios. The magnitude of this negative Os isotope excursion is comparable to those found at Cretaceous-Paleogene boundary sites. These geochemical lines of evidence demonstrate that a large impactor (3.3-7.8 km in diameter) produced a global decrease in seawater (187)Os/(188)Os ratios in the Late Triassic. PMID:24036603

  13. Flow injection kinetic spectrofluorimetric determination of trace amounts of osmium

    NASA Astrophysics Data System (ADS)

    Tang, Bo; Zhang, Hui; Wang, Yan

    2005-07-01

    A flow injection (FI) kinetic spectrofluorimetric method is described for the determination of osmium(IV) and the possible mechanism of catalytic reaction is discussed. The method is based on the fluorescence enhancing reaction of o-vanillin furfuralhydrazone (OVFH) with potassium bromate, which is catalyzed by Os(IV) in water medium at pH 6.10 and 45 °C. OVFH is newly synthesized and its ionization, IR and elemental analysis are established. Under these experimental conditions, the oxidized product of OVFH has excitation and emission maxima at 337 and 490 nm, respectively. The linear range of this method is 0-600 ng ml -1 with the R.S.D. of 1.2%. The detection limit is 1.0 ng ml -1 of Os(IV). A high analysis rate of 24 samples h -1 is obtained by the FI method. The proposed method is applied successfully to determine Os(IV) in synthetic mixture and mineral samples, and the results are well consistent with the standard values.

  14. Allende meteorite: Isotopically anomalous xenon is accompanied by normal osmium

    PubMed Central

    Takahashi, H.; Higuchi, H.; Gros, Jacques; Morgan, John W.; Anders, Edward

    1976-01-01

    The 184Os/190Os ratio of six Allende meteorite samples was determined by neutron activation analysis. Four chromite concentrates gave a ratio differing from the terrestrial ratio by only -0.1 ± 0.4%, although they contained highly anomalous xenon enriched by up to 67% in 124Xe and 93% in 136Xe. In view of this result and the normal isotopic composition of carbon and oxygen in these fractions, it seems very unlikely that the xenon anomalies were produced in a supernova by the p and r processes. More probably, the xenon anomalies were established in the early solar system, by mass fractionation during trapping of noble gases in solids and by spontaneous fission of a superheavy element. Two other samples, containing osmium from the calcium,aluminum-rich inclusions, also gave an 184Os/190Os ratio within -0.1 ± 0.5% of the terrestrial value, although these inclusions show well-established anomalies in the light elements oxygen and magnesium, which appear to be due to pre-solar dust grains of distinctive nuclear history. Apparently the stellar source of the anomalous oxygen and magnesium did not synthesize heavier elements. PMID:16592365

  15. Osmium isotope evidence for a large Late Triassic impact event

    PubMed Central

    Sato, Honami; Onoue, Tetsuji; Nozaki, Tatsuo; Suzuki, Katsuhiko

    2013-01-01

    Anomalously high platinum group element concentrations have previously been reported for Upper Triassic deep-sea sediments, which are interpreted to be derived from an extraterrestrial impact event. Here we report the osmium (Os) isotope fingerprint of an extraterrestrial impact from Upper Triassic chert successions in Japan. Os isotope data exhibit a marked negative excursion from an initial Os isotope ratio (187Os/188Osi) of ∼0.477 to unradiogenic values of ∼0.126 in a platinum group element-enriched claystone layer, indicating the input of meteorite-derived Os into the sediments. The timing of the Os isotope excursion coincides with both elevated Os concentrations and low Re/Os ratios. The magnitude of this negative Os isotope excursion is comparable to those found at Cretaceous–Paleogene boundary sites. These geochemical lines of evidence demonstrate that a large impactor (3.3–7.8 km in diameter) produced a global decrease in seawater 187Os/188Os ratios in the Late Triassic. PMID:24036603

  16. Metal and phosphide phases in Luna 24 soil fragments

    NASA Astrophysics Data System (ADS)

    Axon, H. J.; Nasir, M. J.; Knowles, F.

    1980-06-01

    Soil fragments in the 106-150 and 150-250 micron size ranges were selected for metallographic and microprobe examination on the basis of their magnetic properties. Serial sections of the mounted fragments were examined. One fragment proved to be a compositionally zoned crystal of phosphide with no metal phase but partly embedded in glass. Another was a coarse-grained association of silica with ilmenite and fayalite with a 5-micron particle of metallic iron in troilite. One splinter of oxide contained a central spine of metallic iron. The remaining six fragments contained 10-micron particles of iron-nickel-cobalt alloy with compositions in either the 'meteoritic' or the low Ni-low Co sub-meteoritic composition ranges of Ni, Co content. In some fragments separate particles of alloy had different Ni, Co contents. No particles of high Co metal were encountered.

  17. Vapor-Phase Synthesis of Gallium Phosphide Nanowires

    SciTech Connect

    Gu, Dr Zhanjun; Paranthaman, Mariappan Parans; Pan, Zhengwei

    2009-01-01

    Gallium phosphide (GaP) nanowires were synthesized in a high yield by vapor-phase reaction of gallium vapor and phosphorus vapor at 1150 C in a tube furnace system. The nanowires have diameters in the range of 25-100 nm and lengths of up to tens of micrometers. Twinning growth occurs in GaP nanowires, and as a result most nanowires contain a high density of twinning faults. Novel necklacelike GaP nanostructures that were formed by stringing tens of amorphous Ga-P-O microbeads upon one crystalline GaP nanowires were also found in some synthesis runs. This simple vapor-phase approach may be applied to synthesize other important group III-V compound nanowires.

  18. Band structures in silicene on monolayer gallium phosphide substrate

    NASA Astrophysics Data System (ADS)

    Ren, Miaojuan; Li, Mingming; Zhang, Changwen; Yuan, Min; Li, Ping; Li, Feng; Ji, Weixiao; Chen, Xinlian

    2016-07-01

    Opening a sizable band gap in the zero-gap silicene is a key issue for its application in nanoelectronics. We design new 2D silicene and GaP heterobilayer (Si/GaP HBL) composed of silicene and monolayer (ML) GaP. Based on first-principles calculations, we find that the interaction energies are in the range of -295.5 to -297.5 meV per unit cell, indicating a weak interaction between silicene and gallium phosphide (GaP) monolayer. The band gap changes ranging from 0.06 to 0.44 eV in hybrid HBLs. An unexpected indirect-direct band gap crossover is also observed in HBLs, dependent on the stacking pattern. These provide a possible way to design effective FETs out of silicene on GaP monolayer.

  19. Fabrication and properties of gallium phosphide variable colour displays

    NASA Technical Reports Server (NTRS)

    Effer, D.; Macdonald, R. A.; Macgregor, G. M.; Webb, W. A.; Kennedy, D. I.

    1973-01-01

    The unique properties of single-junction gallium phosphide devices incorporating both red and green radiative recombination centers were investigated in application to the fabrication of monolithic 5 x 7 displays capable of displaying symbolic and alphanumeric information in a multicolor format. A number of potentially suitable material preparation techniques were evaluated in terms of both material properties and device performance. Optimum results were obtained for double liquid-phase-epitaxial process in which an open-tube dipping technique was used for n-layer growth and a sealed tipping procedure for subsequent p-layer growth. It was demonstrated that to prepare devices exhibiting a satisfactory range of dominant wavelengths which can be perceived as distinct emission colors extending from the red through green region of the visible spectrum involves a compromise between the material properties necessary for efficient red emission and those considered optimum for efficient green emission.

  20. A model for pore growth in anodically etched gallium phosphide

    NASA Astrophysics Data System (ADS)

    Ricci, P. C.; Salis, M.; Anedda, A.

    2005-06-01

    The electrochemical etching process of porous gallium phosphide was studied by means of the characteristic current-potential (I-V) curves. Measurements were performed in H2SO4 0.5-M aqueous solution both in the dark and by illuminating the samples with the 351-nm line of an argon laser. Raman spectroscopy was applied to investigate the surface morphology of the samples prepared under different anodizing conditions within the potentiostatic regime. Based on a few reasonable assumptions, a simple model of pore growth is proposed. The enhancing effect in current intensity due to the branching of pores and the opposite effect due to a concomitant decrease in the effective cross area available for carrier transport are accounted for to explain the main features of the recorded I -V curves.

  1. Osmium isotopic ratio measurements by inductively coupled plasma source mass spectrometry

    SciTech Connect

    Russ, G.P. III; Bazan, J.M.; Date, A.R.

    1987-04-01

    The isotopic composition of nanogram quantities of osmium was measured by using an inductively coupled plasma source mass spectrometer. Sensitivity was enhanced a factor of approx.100 by the use of an osmium tetraoxide vapor generator rather than nebulization of solution. For samples less than or equal to5 ng, the ratios /sup 190/Os//sup 192/Os, /sup 189/Os//sup 192/Os, and /sup 188/Os//sup 192/Os were determined to better than +/- 0.5% (1sigma/sub m/) precision. For the minor isotopes, the ratios /sup 187/Os//sup 192/Os and /sup 186/Os//sup 192/Os were determined to +/-1%, and /sup 184/Os//sup 192/Os (4 x 10/sup -4/) was determined to approx.10%. Isotope ratios for common osmium are reported.

  2. Rhenium-osmium isotope constraints on the age of iron meteorites

    USGS Publications Warehouse

    Horan, M.F.; Morgan, J.W.; Walker, R.J.; Grossman, J.N.

    1992-01-01

    Rhenium and osmium concentrations and the osmium isotopic compositions of iron meteorites were determined by negative thermal ionization mass spectrometry. Data for the IIA iron meteorites define an isochron with an uncertainty of approximately ??31 million years for meteorites ???4500 million years old. Although an absolute rhenium-osmium closure age for this iron group cannot be as precisely constrained because of uncertainty in the decay constant of 187Re, an age of 4460 million years ago is the minimum permitted by combined uncertainties. These age constraints imply that the parent body of the IIAB magmatic irons melted and subsequently cooled within 100 million years after the formation of the oldest portions of chondrites. Other iron meteorites plot above the IIA isochron, indicating that the planetary bodies represented by these iron groups may have cooled significantly later than the parent body of the IIA irons.

  3. Estimating the Compressibility of Osmium from Recent Measurements of Ir-Os Alloys under High Pressure.

    PubMed

    Sarlis, Nicholas V; Skordas, Efthimios S

    2016-03-10

    Several fcc- and hcp-structured Ir-Os alloys have been recently studied up to 30 GPa at room temperature by means of synchrotron-based X-ray powder diffraction in diamond anvil cells. Using their bulk moduli, which increase with increasing osmium content, showing a deviation from linearity, and after employing a thermodynamical model, it was concluded that the bulk modulus for osmium is slightly smaller than that for diamond. Here, a similar conclusion is obtained upon employing an alternative model, thus strengthening the conclusion that osmium is the densest but not the most incompressible element. This is particularly interesting for Earth Sciences because it may be of key importance toward clarifying the anomalous elastic properties of the Earth's core. PMID:26890719

  4. Rhenium-osmium-isotope constraints on the age of iron meteorites

    NASA Technical Reports Server (NTRS)

    Horan, M. F.; Morgan, J. W.; Walker, R. J.; Grossman, J. N.

    1992-01-01

    Rhenium and osmium concentrations and the osmium isotopic compositions of iron meteorites were determined by negative thermal ionization mass spectrometry. Data for the IIA iron meteorites define an isochron with an uncertainty of approximately +/-31 million years for meteorites about 4500 million years old. Although an absolute rhenium-osmium closure age for this iron group cannot be as precisely constrained because of uncertainty in the decay constant of Re-187, an age of 4460 million years ago is the minimum permitted by combined uncertainties. These age constraints imply that the parent body of the IIAB magmatic irons melted and subsequently cooled within 100 million years after the formation of the oldest portions of chondrites. Other iron meteorites plot above the IIA isochron, indicating that the planetary bodies represented by these iron groups may have cooled significantly later than the parent body of the IIA irons.

  5. Cluster decay in osmium isotopes using Hartree-Fock-Bogoliubov theory

    NASA Astrophysics Data System (ADS)

    Ashok, Nithu; Joseph, Deepthy Maria; Joseph, Antony

    2016-02-01

    Cluster radioactivity is a rare cold nuclear process which is intermediate between alpha decay and spontaneous fission. The present work is a theoretical investigation of the feasibility of alpha decay and cluster radioactivity from proton rich Osmium (Os) isotopes with mass number ranging from 162-190. Osmium forms a part of the transition region between highly deformed and spherical nuclei. Calculations have been done using unified fission model and Hartree-Fock-Bogoliubov (HFB) theory. We have chosen only those decays with half-lives falling in measurable range. Geiger-Nuttall plot has been successfully reproduced. The isotope which is most favorable to each decay mode has a magic daughter nucleus.

  6. Low earth orbit environmental effects on osmium and related optical thin-film coatings

    NASA Technical Reports Server (NTRS)

    Gull, T. R.; Herzig, H.; Osantowski, J. F.; Toft, A. R.

    1985-01-01

    A number of samples of optical thin film materials were flown on Shuttle flight STS-8 as part of an experiment to evaluate their interaction with residual atomic oxygen in low earth orbit. Osmium was selected because of its usefulness as a reflective optical coating for far-UV instruments and for confirmation of results from previous Shuttle flights in which such coatings disappeared. Reflectance data and photographic evidence are presented to support the hypothesis that the osmium disappearance is due to reaction with oxygen to form a volatile oxide. Platinum and iridium, which were included for comparison, fared much better.

  7. Conductive polymers derived from iron, ruthenium, and osmium metalloporphyrins: The shish-kebab approach

    PubMed Central

    Collman, James P.; McDevitt, John T.; Yee, Gordon T.; Leidner, Charles R.; McCullough, Laughlin G.; Little, William A.; Torrance, Jerry B.

    1986-01-01

    The synthesis and characterization of pyrazine-bridged polymers of iron(II/III), ruthenium(II/III), and osmium(II/III) octaethylporphyrin (dubbed “shish-kebab” polymers) are presented. Optical and dc conductivity measurements reveal that the ruthenium and osmium polymers, when partially oxidized, are highly conductive. Electrochemical and ESR results are presented that indicate the existence of an interesting metal-centered conduction pathway. Unlike most of the previously reported porphyrinic molecular metals in which the conduction electrons are macrocyclic-based, electron transport in these materials proceeds exclusively along the metal-pyrazine backbone. PMID:16593717

  8. Osmium isotopic evidence for ancient subcontinental lithospheric mantle beneath the kerguelen islands, southern indian ocean

    PubMed

    Hassler; Shimizu

    1998-04-17

    Upper mantle xenoliths found in ocean island basalts are an important window through which the oceanic mantle lithosphere may be viewed directly. Osmium isotopic data on peridotite xenoliths from the Kerguelen Islands, an archipelago that is located on the northern Kerguelen Plateau in the southern Indian Ocean, demonstrate that pieces of mantle of diverse provenance are present beneath the Islands. In particular, peridotites with unradiogenic osmium and ancient rhenium-depletion ages (to 1.36 x 10(9) years old) may be pieces of the Gondwanaland subcontinental lithosphere that were incorporated into the Indian Ocean lithosphere as a result of the rifting process. PMID:9545216

  9. Reply to "Comment on two-phonon gamma-vibrational strength in osmium nuclei"

    SciTech Connect

    Wu, C.Y.; Cline, D.; Hayes, A.B.; Simon, M.W.; Krueken, R.; Cooper, J.R.; Barton, C.J.; Beausang, C.W.; Bialik, C.; Caprio, M.A.; Casten, R.F.; Hecht, A.A.; Newman, H.; Novak, J.; Pietralla, N.; Zyromski, K.; Zamfir, N.V.

    2002-09-03

    The claim that the two-phonon gamma-vibrational configuration constitutes a major component for the I=4+ states in osmium nuclei is based on solid experimental evidence. A non-negligible two-quasiparticle or hexadecapole component must also exist in order to explain the data.

  10. Anthropogenic osmium in rain and snow reveals global-scale atmospheric contamination

    PubMed Central

    Chen, Cynthia; Sedwick, Peter N.; Sharma, Mukul

    2009-01-01

    Osmium is one of the rarer elements in seawater, with typical concentration of ≈10 × 10−15 g g−1 (5.3 × 10−14 mol kg−1). The osmium isotope composition (187Os/188Os ratio) of deep oceans is 1.05, reflecting a balance between inputs from continental crust (≈1.3) and mantle/cosmic dust (≈0.13). Here, we show that the 187Os/188Os ratios measured in rain and snow collected around the world range from 0.16 to 0.48, much lower than expected (>1), but similar to the isotope composition of ores (≈0.2) that are processed to extract platinum and other metals to be used primarily in automobile catalytic converters. Present-day surface seawater has a lower 187Os/188Os ratio (≈0.95) than deep waters, suggesting that human activities have altered the isotope composition of the world's oceans and impacted the global geochemical cycle of osmium. The contamination of the surface ocean is particularly remarkable given that osmium has few industrial uses. The pollution may increase with growing demand for platinum-based catalysts. PMID:19416862

  11. Andreyivanovite: A Second New Phosphide from the Kaidun Meteorite

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael

    2008-01-01

    Andreyivanovite (ideally FeCrP) is another new phosphide species from the Kaidun meteorite, which fell in South Yemen in 1980. Kaidun is a unique breccia containing an unprecedented variety of fragments of different chondritic as well as achondritic lithologies. Andreyivanovite was found as individual grains and linear arrays of grains with a maximum dimension of 8 m within two masses of Fe-rich serpentine. In one sample it is associated with Fe-Ni-Cr sulfides and florenskyite (FeTiP). Andreyivanovite is creamy white in reflected light, and its luster is metallic. The average of nine electron microprobe analyses yielded the formula Fe(Cr0.587 Fe0.150 V0.109 Ti0.081 Ni0.060 Co0.002)P. Examination of single grains of andreyivanovite using Laue patterns collected by in-situ synchrotron X-ray diffraction (XRD), and by electron backscattered diffraction revealed that it is isostructural with florenskyite; we were unable to find single crystals of sufficient quality to perform a complete structure analysis. Andreyivanovite crystallizes in the space group Pnma, and has the anti-PbCl2 structure. Previously-determined cell constants of synthetic material [a = 5.833(1), b = 3.569(1), c = 6.658(1) A] were consistent with our XRD work. We used the XPOW program to calculate a powder XRD pattern; the 5 most intense reflections are d = 2.247 (I = 100), 2.074 (81), 2.258 (46), 1.785 (43), and 1.885 A (34). Andreyivanovite is the second new phosphide to be described from the Kaidun meteorite. Andreyivanovite could have formed as a result of cooling and crystallization of a melted precursor consisting mainly of Fe-Ni metal enriched in P, Ti, and Cr. Serpentine associated with andreyivanovite would then have formed during aqueous alteration on the parent asteroid. It is also possible that the andreyivanovite could have formed during aqueous alteration, however, artificial FeTiP has been synthesized only during melting experiments, at low oxygen fugacity, and there is no evidence that

  12. The potential impact of municipal solid waste incinerators ashes on the anthropogenic osmium budget.

    PubMed

    Funari, Valerio; Meisel, Thomas; Braga, Roberto

    2016-01-15

    Osmium release from Municipal Solid Waste Incinerators (MSWI), even if acknowledged to occur at least over the last fifteen years, remains overlooked in the majority of recent studies. We present the osmium concentration and (187)Os/(188)Os isotopic measurements of different kinds of bottom and fly ash samples from MSWI plants and reference materials of incinerator fly ash (BCR176 and BCR176R). The analysis of the unknown ash samples shows a relatively wide range of (187)Os/(188)Os ratios (0.24-0.70) and Os concentrations (from 0.026 ng/g to 1.65 ng/g). Osmium concentrations and isotopic signatures differ from those of other known Os sources, either natural or manmade, suggesting a mixture of both contributions in the MSWI feedstock material. Furthermore, the comparison between the BCR176 and the renewed BCR176R indicates a decrease in Os concentration of one order of magnitude over the years (from 1 to 0.1 ng/g) due to improved recycling efficiency of Os-bearing waste. The estimated annual amount of Os from a typical incinerator (using average Os values and MSWI mass balance) is 13.4 g/a. The osmium potentially released from MSWI smokestacks is predicted to be from 16 to 38 ng Os/m(2)/a, considering a medium size country having 50 MSWI facilities; therefore much higher than the naturally transported osmium from continental dust in the atmosphere (about 1 pg Os/m(2)/a). MSWI systems are considered one of the best options for municipal solid waste management in industrialised countries, but their contribution to the Os budget can be significant. PMID:26490532

  13. An Entry to Stable Mixed Phosphine-Osmium-NHC Polyhydrides.

    PubMed

    Buil, María L; Cardo, Juan J F; Esteruelas, Miguel A; Fernández, Israel; Oñate, Enrique

    2016-05-16

    An entry to mixed phosphine-osmium-NHC polyhydride complexes is described, starting from the five-coordinate hydrido-alkylidyne compounds [OsHCl(≡CPh)(IPr)(PR3)]OTf (IPr = 1,3-bis(2,6-disopropylphenyl)imidazolylidene; OTf = CF3SO3; PR3 = P(i)Pr3 (1), PPh3 (2)). The experimental procedure involves the borylation of the Os-C triple bond of 1 and 2 with NaBH4 and the subsequent alcoholysis of the borylation products OsH2Cl(η(2)-H-BCH2Ph)(IPr)(PR3) (PR3 = P(i)Pr3 (3), PPh3 (4)) or OsH2(η(2):η(2):H2BCH2Ph)(IPr)(P(i)Pr3) (5). Stirring of 3 in 2-propanol affords the five coordinate chloride-trihydride OsH3Cl(IPr)(P(i)Pr3)2 (6), which reacts with NaBH4 to give OsH3(κ(2)-H2BH2)(IPr)(P(i)Pr3) (7). This trihydride-tetrahydrideborate derivative and its PPh3 counterpart OsH3(κ(2)-H2BH2)(IPr)(PPh3) (8) can be also obtained in a one-pot procedure, starting from 1 and 2 and using methanol at -60 °C instead of 2-propanol as alcoholysis agent. The bonding situation in 7 and 8, analyzed by DFT calculations using AIM and NBO methods, resembles that found in B2H6 and contrasts with the bonding situation in the bis-σ-borane derivative 5. Stirring of 7 and 8 in 2-propanol leads to the corresponding d(2)-hexahydride derivatives OsH6(IPr)(PR3) (PR3 = P(i)Pr3 (9), PPh3 (10)), which reduce the C≡N triple bond of benzonitrile and promote the subsequent chelate-assisted ortho-CH bond activation of the resulting phenylmethanimine, to form the trihydride compounds OsH3{κ(2)-N,C-(NH═CH-C6H4)}(IPr)(PR3)2 (PR3 = P(i)Pr3 (11), PPh3 (12)), containing a stabilized orthometalated aldimine. PMID:27145380

  14. A case of accidental fatal aluminum phosphide poisoning involving humans and dogs.

    PubMed

    Behera, Chittaranjan; Krishna, Karthik; Bhardwaj, Daya Nand; Rautji, Ravi; Kumar, Arvind

    2015-05-01

    Aluminum phosphide is one of the commonest poisons encountered in agricultural areas, and manner of death in the victims is often suicidal and rarely homicidal or accidental. This paper presents an unusual case, where two humans (owner and housemaid) and eight dogs were found dead in the morning hours inside a room of a house, used as shelter for stray dogs. There was allegation by the son of the owner that his father had been killed. Crime scene visit by forensic pathologists helped to collect vital evidence. Autopsies of both the human victims and the dogs were conducted. Toxicological analysis of viscera, vomitus, leftover food, and chemical container at the crime scene tested positive for aluminum phosphide. The cause of death in both humans and dogs was aluminum phosphide poisoning. Investigation by police and the forensic approach to the case helped in ascertaining the manner of death, which was accidental. PMID:25707792

  15. Method of synthesizing bulk transition metal carbide, nitride and phosphide catalysts

    DOEpatents

    Choi, Jae Soon; Armstrong, Beth L; Schwartz, Viviane

    2015-04-21

    A method for synthesizing catalyst beads of bulk transmission metal carbides, nitrides and phosphides is provided. The method includes providing an aqueous suspension of transition metal oxide particles in a gel forming base, dropping the suspension into an aqueous solution to form a gel bead matrix, heating the bead to remove the binder, and carburizing, nitriding or phosphiding the bead to form a transition metal carbide, nitride, or phosphide catalyst bead. The method can be tuned for control of porosity, mechanical strength, and dopant content of the beads. The produced catalyst beads are catalytically active, mechanically robust, and suitable for packed-bed reactor applications. The produced catalyst beads are suitable for biomass conversion, petrochemistry, petroleum refining, electrocatalysis, and other applications.

  16. Ab-initio Calculations of Electronic Properties of Boron Phosphide (BP)

    NASA Astrophysics Data System (ADS)

    Ejembi, John; Franklin, Lashaunda; Malozovsky, Yuriy; Bagayoko, Diola

    2014-03-01

    We present results from ab-initio, self consistent local density approximation (LDA) calculations of electronic and related properties of zinc blende boron phosphide (BP). We employed a local density approximation (LDA) potential and implemented the linear combination of atomic orbitals (LCAO) formalism. This implementation followed the Bagayoko, Zhao, and Williams (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF). We discuss our preliminary results for the indirect band gap, from Γ to X, of Boron Phosphide. We also report calculated electron and hole effective masses for Boron Phosphide and total (DOS) and partial (pDOS) density of states. Acknowledgments: This research is funded in part by the National Science Foundation (NSF) and the Louisiana Board of Regents, through LASiGMA [Award Nos. EPS- 1003897, NSF (2010-15)-RII-SUBR] and NSF HRD-1002541, the US Department of Energy - National, Nuclear Security Administration (NNSA) (Award No. DE-NA0001861), LaSPACE, and LONI-SUBR.

  17. Photonic integration in indium-phosphide membranes on silicon (IMOS)

    NASA Astrophysics Data System (ADS)

    van der Tol, Jos; Pello, Josselin; Bhat, Shrivatsa; Jiao, Yuqing; Heiss, Dominik; Roelkens, Gunther; Ambrosius, Huub; Smit, Meint

    2014-03-01

    A new photonic integration technique is presented, based on the use of an indium phosphide membrane on top of a silicon chip. This can provide electronic chips (CMOS) with an added optical layer (IMOS) for resolving the communication bottleneck. A major advantage of InP is the possibility to integrate passive and active components (SOAs, lasers) in a single membrane. In this paper we describe progress achieved in both the passive and active components. For the passive part of the circuit we succeeded to bring the propagation loss of our circuits close to the values obtained with silicon; we achieved propagation loss as low as 3.3 dB/cm through optimization of the lithography and the introduction of C60 (fullerene) in an electro resist. Further we report the smallest polarisation converter reported for membrane waveguides ( <10 μm) with low-loss (< 1 dB from 1520- 1550 nm), > 95% polarisation conversion efficiency over the whole C-band and tolerant fabrication. We also demonstrate an InP-membrane wavelength demultiplexer with a loss of 2.8 dB, a crosstalk level of better than 18 dB and a uniformity over the 8 channels of better than 1.2 dB. For the integration of active components we are testing a twin guide integration scheme. We present our design based on optical and electrical simulations and the fabrication techniques.

  18. Comparative performance of diffused junction indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Swartz, C. K.; Hart, R. E., Jr.; Ghandhi, S. K.; Borrego, J. M.; Parat, K. K.

    1987-01-01

    A comparison is made between indium phosphide solar cells whose p-n junctions were processed by open tube capped diffusion, and closed tube uncapped diffusion, of sulfur into Czochralski grown p-type substrates. Air mass zero, total area, efficiencies ranged from 10 to 14.2 percent, the latter value attributed to cells processed by capped diffusion. The radiation resistance of these latter cells was slightly better, under 1 MeV electron irradiation. However, rather than being process dependent, the difference in radiation resistance could be attributed to the effects of increased base dopant concentration. In agreement with previous results, both cells exhibited radiation resistance superior to that of gallium arsenide. The lowest temperature dependency of maximum power was exhibited by the cells prepared by open tube capped diffusion. Contrary to previous results, no correlation was found between open circuit voltage and the temperature dependency of Pmax. It was concluded that additional process optimization was necessary before concluding that one process was better than another.

  19. Optical Properties of Strained Wurtzite Gallium Phosphide Nanowires

    PubMed Central

    2016-01-01

    Wurtzite gallium phosphide (WZ GaP) has been predicted to exhibit a direct bandgap in the green spectral range. Optical transitions, however, are only weakly allowed by the symmetry of the bands. While efficient luminescence has been experimentally shown, the nature of the transitions is not yet clear. Here we apply tensile strain up to 6% and investigate the evolution of the photoluminescence (PL) spectrum of WZ GaP nanowires (NWs). The pressure and polarization dependence of the emission together with a theoretical analysis of strain effects is employed to establish the nature and symmetry of the transitions. We identify the emission lines to be related to localized states with significant admixture of Γ7c symmetry and not exclusively related to the Γ8c conduction band minimum (CBM). The results emphasize the importance of strongly bound state-related emission in the pseudodirect semiconductor WZ GaP and contribute significantly to the understanding of the optoelectronic properties of this novel material. PMID:27175743

  20. Optical Properties of Strained Wurtzite Gallium Phosphide Nanowires.

    PubMed

    Greil, J; Assali, S; Isono, Y; Belabbes, A; Bechstedt, F; Valega Mackenzie, F O; Silov, A Yu; Bakkers, E P A M; Haverkort, J E M

    2016-06-01

    Wurtzite gallium phosphide (WZ GaP) has been predicted to exhibit a direct bandgap in the green spectral range. Optical transitions, however, are only weakly allowed by the symmetry of the bands. While efficient luminescence has been experimentally shown, the nature of the transitions is not yet clear. Here we apply tensile strain up to 6% and investigate the evolution of the photoluminescence (PL) spectrum of WZ GaP nanowires (NWs). The pressure and polarization dependence of the emission together with a theoretical analysis of strain effects is employed to establish the nature and symmetry of the transitions. We identify the emission lines to be related to localized states with significant admixture of Γ7c symmetry and not exclusively related to the Γ8c conduction band minimum (CBM). The results emphasize the importance of strongly bound state-related emission in the pseudodirect semiconductor WZ GaP and contribute significantly to the understanding of the optoelectronic properties of this novel material. PMID:27175743

  1. Unresponsive ventricular tachycardia associated with aluminum phosphide poisoning.

    PubMed

    Jadhav, Amar P; Nusair, Maein B; Ingole, Apekshe; Alpert, Martin A

    2012-05-01

    Inhalation or ingestion of aluminum phosphide (AP) generates phosphine gas on exposure to moisture, which, in turn, produces widespread organ toxicity primarily involving the lungs, heart, liver, and kidneys. Cardiac manifestations of AP poisoning include toxic myocarditis, refractory heart failure, bradyarrhythmias, and tachyarrhythmias including ventricular tachycardia (VT). A 19-year-old depressed male farm worker ingested ten 500-mg tablets of Celphos in a suicide attempt. Each Celphos tablet contains 56% AP. Over the course of 10 hours, the patient developed heart failure and respiratory failure associated with a rise in serum troponin level to 12.7 ng/mL. Serum electrolytes (including magnesium) and serum creatinine levels were normal throughout. His course was further complicated by acidemia and hypotension. These hemodynamic and metabolic abnormalities were initially corrected by assisted ventilation and continuous veno-venous hemofiltration. However, he developed hemodynamically stable sustained monomorphic VT, which proved unresponsive to treatment with intravenous magnesium sulfate and intravenous amiodarone therapy. After a decline in blood pressure, 6 attempts at electrocardioversion failed to restore sinus rhythm, and he died. Postmortem histologic examination of myocardium showed contraction band necrosis, early coagulation necrosis, edema, hemorrhage, and pyknosis of cardiac myocyte nuclei. Ventricular tachycardia associated with AP poisoning has been successfully treated with magnesium sulfate, amiodarone, and electrocardioversion. This case report documents failure of all 3 of these therapeutic modalities. PMID:21406319

  2. Superconductivity in the Hexagonal Ternary Phosphide ScIrP

    NASA Astrophysics Data System (ADS)

    Okamoto, Yoshihiko; Inohara, Takumi; Yamakawa, Youichi; Yamakage, Ai; Takenaka, Koshi

    2016-01-01

    We report the discovery of a bulk superconducting transition at 3.4 K in the ternary phosphide, ScIrP, which crystallizes in a hexagonal ZrNiAl-type structure without spatial inversion symmetry. On the basis of heat capacity data in a zero magnetic field, ScIrP is suggested to be a weakly-coupled Bardeen-Cooper-Schrieffer superconductor. Alternatively, experimental results under magnetic fields indicate that this material is a type-II superconductor with an upper critical field Hc2 at magnetic fields above 5 T at zero temperature. This moderately high Hc2 does not violate the Pauli limit, but it does imply that there is a significant effect from the strong spin-orbit interaction of Ir 5d electrons in the noncentrosymmetric crystal structure. Electronic structure calculations show an interesting feature of ScIrP, where both the Sc 3d and Ir 5d orbitals contribute to the electronic density of states at the Fermi level.

  3. Therapeutic role of hyperinsulinemia/euglycemia in aluminum phosphide poisoning

    PubMed Central

    Hassanian-Moghaddam, Hossein; Zamani, Nasim

    2016-01-01

    Abstract Background: Different protocols have been suggested to treat aluminum phosphide (ALP) poisoning. We aimed to evaluate the possible therapeutic effect of hyperinsulinemia/euglycemia (HIE) in treatment of ALP poisoning. Methods: In a prospective interventional study, a total of 88 ALP-poisoned patients were included and assigned into HIE group undergoing glucose/insulin/potassium (GIK) protocol and a control group that was managed by routine conventional treatments. The 2 groups were then compared regarding the signs and symptoms of toxicity and their progression, development of complications, and final outcome to detect the possible effect of GIK protocol on the patients’ course of toxicity and outcome. Results: The 2 groups were similar in terms of demographic characteristics and on-arrival vital signs and lab tests. Using GIK protocol resulted in significantly longer hospital stays (24 vs 60 hours; P < 0.001) and better outcomes (72.7% vs 50% mortality; P = 0.03). Regression analysis showed that GIK duration was an independent variable that could prognosticate mortality (odds ratio [95% confidence interval] = 1.045 [1.004,1.087]). The risk of mortality decreased by 4.5% each hour after initiation of GIK. Conclusion: GIK protocol improves the outcome of ALP poisoning and increases the length of hospital stay. PMID:27495040

  4. Successful Treatment of Aluminium Phosphide Poisoning by Extracorporeal Membrane Oxygenation.

    PubMed

    Hassanian-Moghaddam, Hossein; Zamani, Nasim; Rahimi, Mitra; Hajesmaeili, Mohammadreza; Taherkhani, Maryam; Sadeghi, Roxana

    2016-03-01

    Aluminium phosphide (ALP) is one of the most commonly used pesticides worldwide with high mortality rates. Cellular damage and cardiorespiratory failure are the most common causes of mortality and morbidity after poisoning. It is supposed that giving enough time to the patient to survive, the most critical hours after exposure may help the cardiovascular system to recover itself and save the patient's life. During a training workshop for medical extracorporeal membrane oxygenation (ECMO), a 28-year-old ALP-poisoned male was referred to us. Fifty minutes after admission, he developed hypotension and bradycardia and was transferred to ICU. On the second venous blood gas, he had severe metabolic acidosis. After starting the patient on the routine treatment of ALP poisoning, he was a candidate for veno-arterial (VA) ECMO. After three days, lactate level decreased and his general condition improved. On day four, the patient was completely separated from the ECMO machine with acceptable echocardiography and ejection fraction of 40%. One day later, he was extubated, sent to the ward and subsequently discharged in good condition. We suggest this method of treatment for severe ALP poisoning as well as any other poisoning that causes cell toxicity and abrupt cardiovascular or respiratory failure. PMID:26335576

  5. Unexpected Stable Two-dimensional Silicon Phosphides with Different Stoichiometries

    DOE PAGESBeta

    Yoon, Mina; Wei, Su-Huai; Sumpter, Bobby G

    2015-01-01

    The discovery of stable two-dimensional, earth-abundant, semiconducting materials is of great interest and may impact future electronic technologies. By combining global structural prediction and first-principles calculations, we have theoretically discovered several previously unknown semiconducting silicon phosphides (SixPy) monolayers, which could be formed stably at the stoichiometries of y/x1. Unexpectedly, some of these compounds, i.e., P-6m2 Si1P1 and Pm Si1P2, have comparable or even lower formation enthalpies than their previously known bulk allotropes. The band gaps (Eg) of SixPy compounds can be dramatically tuned in an extremely wide range (0< Eg < 3 eV) by simply changing the number of layersmore » or applying an in-plane strain. Moreover, we find that carrier doping can drive the ground state of C2/m Si1P3 from a nonmagnetic state into a robust half-metallic spin-polarized state, originating from its unique valence band structure, which can extend the use of Si-related compounds for spintronics.« less

  6. Spectrophotometric reaction rate method for the determination of osmium by its catalytic effect on the oxidation of gallocyanine by bromate.

    PubMed

    Ensafi, A A; Shamss-E-Sollari, E

    1994-10-01

    A simple kinetic spectrophotometric method was developed for the determination of osmium. The method is based on the catalytic effect of osmium as osmium tetroxide on the oxidation of gallocyanine by bromate at pH 7. The reaction is monitored spectrophotometrically by measuring the decreasing absorbance of gallocyanine at 620 nm by the fixed-time method. A detection limit of 0.01 ng/ml and linear calibration curve from 0.1 to 100 and from 100 to 1200 ng/ml Os(VIII) is reported. The relative standard deviation for 0.0100 microg/ml Os(VIII) is 0.8% (N = 10). The method is free from most interferences. Osmium in synthetic samples is determined by this method, with satisfactory results. PMID:18966116

  7. On line vapor generation of osmium based on solution cathode glow discharge for the determination by ICP-OES.

    PubMed

    Zhu, Zhenli; Huang, Chunying; He, Qian; Xiao, Qing; Liu, Zhifu; Zhang, Suicheng; Hu, Shenghong

    2013-03-15

    A novel plasma induced vapor generation method is proposed to determine osmium in solutions. Without any chemical oxidizing agents, osmium ion can be readily converted to volatile osmium tetraoxide vapor in the solution cathode glow discharge (SCGD) system. The generated osmium vapor is then transported to inductively coupled plasma for determination by optical emission spectrometry. The influences of background electrolyte, carrier gas flow rate, sample flow rate, ICP power and discharge current were investigated. The analytical performances of this proposed technique were evaluated under optimized conditions. The detection limit of Os was calculated to be 0.51 ng mL(-1). The reproducibility, expressed as the relative standard deviation (n=11) of a 2.0 μg mL(-1) standard solution, was 1.9%. This SCGD induced vapor generation is sensitive and simple, oxidation reagents free, providing an alternative analytical method for measuring Os in geological or environmental water samples. PMID:23598105

  8. Severe reversible myocardial injury associated with aluminium phosphide toxicity: A case report and review of literature.

    PubMed

    Elabbassi, Wael; Chowdhury, Mohammed Andaleeb; Fachtartz, Arif Al Nooryani

    2014-10-01

    Aluminium phosphide is commonly used as an insecticide and can be toxic to humans at the cellular level by interfering with mitochondrial energy metabolism. We report on three cases of severe aluminium phosphide cardio-toxicity, resulting in severe decrease in both ventricular heart functions. The first case succumbed to intractable ventricular arrhythmias complicated by multi-organ failure before she died; while the other two cases required invasive hemodynamic support and eventually improved over the course of 10-14 days. We describe our experience and the challenges faced while managing one of them. PMID:25278724

  9. Indium phosphide solar cells - Recent developments and estimated performance in space

    NASA Technical Reports Server (NTRS)

    Weinberg, Irving; Brinker, David J.

    1990-01-01

    The current status of indium phosphide solar cell research is reviewed. In the NASA research program, efficiencies of 18.8 percent were achieved for standard n/p homojunction InP cells while 17 percent was achieved for ITO/InP cells processed by sputtering n-type indium tin oxide onto p-type indium phosphide. The latter represents a cheaper, simpler processing alternative. Computer modeling calculations indicate that efficiencies of over 21 percent are feasible. Relatively large area cells are produced in Japan with a maximum efficiency of 16.6 percent.

  10. New method for the measurement of osmium isotopes applied to a New Zealand Cretaceous/Tertiary boundary shale

    USGS Publications Warehouse

    Lichte, F.E.; Wilson, S.M.; Brooks, R.R.; Reeves, R.D.; Holzbecher, J.; Ryan, D.E.

    1986-01-01

    The determination of osmium content and isotopic abundances in geological materials has received increasing attention in recent years following the proposal of Alvarez et al.1 that mass extinctions at the end of the Cretaceous period were caused by the impact of a large (???10km) meteorite which left anomalously high iridium levels as a geochemical signature in the boundary shales. Here we report a new and simple method for measuring osmium in geological materials, involving fusion of the sample with sodium peroxide, distillation of the osmium as the tetroxide using perchloric acid, extraction into chloroform, and absorption of the chloroform extract onto graphite powder before instrumental neutron activation analysis. In a variant of this technique, the chloroform extract is back-extracted into an aqueous phase and the osmium isotopes are determined by plasma-source mass spectrometry (ICPMS). We have used this method on the Woodside Creek (New Zealand) Cretaceous/Tertiary boundary clay and have obtained the first osmium content (6g ng g-1) for this material. The 187Os/186Os ratio is 1.12??0.16, showing a typical non-crustal signature. This combined distillation-extraction- ICPMS method will prove to be useful for measuring osmium isotopes in other geological materials. ?? 1986 Nature Publishing Group.

  11. Boron Arsenide and Boron Phosphide for High Temperature and Luminescent Devices. [semiconductor devices - crystal growth/crystal structure

    NASA Technical Reports Server (NTRS)

    Chu, T. L.

    1975-01-01

    The crystal growth of boron arsenide and boron phosphide in the form of bulk crystals and epitaxial layers on suitable substrates is discussed. The physical, chemical, and electrical properties of the crystals and epitaxial layers are examined. Bulk crystals of boron arsenide were prepared by the chemical transport technique, and their carrier concentration and Hall mobility were measured. The growth of boron arsenide crystals from high temperature solutions was attempted without success. Bulk crystals of boron phosphide were also prepared by chemical transport and solution growth techniques. Techniques required for the fabrication of boron phosphide devices such as junction shaping, diffusion, and contact formation were investigated. Alloying techniques were developed for the formation of low-resistance ohmic contacts to boron phosphide. Four types of boron phosphide devices were fabricated: (1) metal-insulator-boron phosphide structures, (2) Schottky barriers; (3) boron phosphide-silicon carbide heterojunctions; and (4) p-n homojunctions. Easily visible red electroluminescence was observed from both epitaxial and solution grown p-n junctions.

  12. Osmium isotopes and the Upper Devonian "Kellwasser" event

    NASA Astrophysics Data System (ADS)

    Brauns, M.

    2001-12-01

    at least for the studied localities: (I) The Os isotopic composition of all limestone and shale samples as well as separated biogenic/diagenetic rock components is very radiogenic. Even the conodonts reveal no obvious contribution of primitive Os supplied by extraterrestrial material, as would be expected when considering the meteoric impact theory. Thus, such an event at the Frasne/Famenne boundary appears to be highly improbable. (II) A drastic peak reflecting elevated Re, Os concentrations during the upper gigas subzone may point to an enhanced clastic input of upper crustal material to the Kellwasser sea. Brauns, M. (2001): A rapid, low-blank technique for the extraction of Osmium from geological samples. Chem. Geol. In press. Schindler, E. (1990): Die Kellwasser - Krise (hohe Frasne-Stufe, Ober-Devon). Diss. Göttingen. 116 S. Tagami, K. & Uchida, S. (2000): Separation of rhenium by an extraction chromatograpic resin for determination by inductively coupled plasma-mass-spectrometry. Anal. Chim. Acta. 405, 227-229.

  13. Indium Phosphide Window Layers for Indium Gallium Arsenide Solar Cells

    NASA Technical Reports Server (NTRS)

    Jain, Raj K.

    2005-01-01

    Window layers help in reducing the surface recombination at the emitter surface of the solar cells resulting in significant improvement in energy conversion efficiency. Indium gallium arsenide (In(x)Ga(1-x)As) and related materials based solar cells are quite promising for photovoltaic and thermophotovoltaic applications. The flexibility of the change in the bandgap energy and the growth of InGaAs on different substrates make this material very attractive for multi-bandgap energy, multi-junction solar cell approaches. The high efficiency and better radiation performance of the solar cell structures based on InGaAs make them suitable for space power applications. This work investigates the suitability of indium phosphide (InP) window layers for lattice-matched In(0.53)Ga(0.47)As (bandgap energy 0.74 eV) solar cells. We present the first data on the effects of the p-type InP window layer on p-on-n lattice-matched InGaAs solar cells. The modeled quantum efficiency results show a significant improvement in the blue region with the InP window. The bare InGaAs solar cell performance suffers due to high surface recombination velocity (10(exp 7) cm/s). The large band discontinuity at the InP/InGaAs heterojunction offers a great potential barrier to minority carriers. The calculated results demonstrate that the InP window layer effectively passivates the solar cell front surface, hence resulting in reduced surface recombination and therefore, significantly improving the performance of the InGaAs solar cell.

  14. Rhenium-osmium concentration and isotope systematics in group IIAB iron meteorites

    USGS Publications Warehouse

    Morgan, J.W.; Horan, M.F.; Walker, R.J.; Grossman, J.N.

    1995-01-01

    Rhenium and osmium abundances, and osmium isotopic compositions were measured by negative thermal ionization mass spectrometry in thirty samples, including replicates, of five IIA and eight IIB iron meteorites. Log plots of Os vs. Re abundances for IIA and IIB irons describe straight lines that approximately converge on Lombard, which has the lowest Re and Os abundances and highest 187Re/188Os measured in a IIA iron to date. The linear IIA trend may be exactly reproduced by fractional crystallization, but is not well fitted using variable partition coefficients. The IIB iron trend, however, cannot be entirely explained by simple fractional crystallization. One explanation is that small amounts of Re and Os were added to the asteroid core during the final stages of crystallization. Another possibility is that diffusional enrichment of Os may have occurred in samples most depleted in Re and Os. -from Authors

  15. Bidentate Ligands on Osmium(VI) Nitrido Complexes Control Intracellular Targeting and Cell Death Pathways

    PubMed Central

    Suntharalingam, Kogularamanan; Johnstone, Timothy C.; Bruno, Peter M.; Lin, Wei; Hemann, Michael T.; Lippard, Stephen J.

    2013-01-01

    The cellular response evoked by anti-proliferating osmium(VI) nitrido compounds of general formula OsN(N^N)Cl3 (N^N = 2,2′-bipyridine 1, 1,10-phenanthroline 2, 3,4,7,8-tetramethyl-1,10-phenanthroline 3, or 4,7-diphenyl-1,10-phenanthroline 4) can be tuned by subtle ligand modifications. Complex 2 induces DNA damage, resulting in activation of the p53 pathway, cell cycle arrest at the G2/M phase, and caspase-dependent apoptotic cell death. In contrast, 4 evokes ER stress leading to the upregulation of proteins of the unfolded protein response pathway, increase in ER size, and p53-independent apoptotic cell death. To the best of our knowledge, 4 is the first osmium compound to induce ER stress in cancer cells. PMID:24041161

  16. Facile synthesis of iron phosphide nanorods for efficient and durable electrochemical oxygen evolution.

    PubMed

    Xiong, Dehua; Wang, Xiaoguang; Li, Wei; Liu, Lifeng

    2016-07-01

    Iron phosphide (FeP) nanorods have been fabricated by a facile hydrothermal synthesis of iron oxyhydroxide precursors, followed by a convenient phosphorization process. The FeP nanorods dispersed on carbon fiber paper current collectors exhibit outstanding catalytic activity and excellent long-term stability toward the oxygen evolution reaction (OER). PMID:27333123

  17. General Strategy for the Synthesis of Transition Metal Phosphide Films for Electrocatalytic Hydrogen and Oxygen Evolution.

    PubMed

    Read, Carlos G; Callejas, Juan F; Holder, Cameron F; Schaak, Raymond E

    2016-05-25

    Transition metal phosphides recently have been identified as promising Earth-abundant electrocatalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Here, we present a general and scalable strategy for the synthesis of transition metal phosphide electrodes based on the reaction of commercially available metal foils (Fe, Co, Ni, Cu, and NiFe) with various organophosphine reagents. The resulting phosphide electrodes were found to exhibit excellent electrocatalytic HER and OER performance. The most active electrodes required overpotentials of only -128 mV for the HER in acid (Ni2P), -183 mV for the HER in base (Ni2P), and 277 mV for the OER in base (NiFeP) to produce operationally relevant current densities of 10 mA cm(-2). Such HER and OER performance compares favorably with samples prepared using significantly more elaborate and costly procedures. Furthermore, we demonstrate that the approach can also be utilized to obtain highly active and conformal metal phosphide coatings on photocathode materials, such as highly doped Si, that are relevant to solar fuels production. PMID:27156388

  18. Ligand-free osmium clusters supported on MgO. A density functional study

    SciTech Connect

    Goellner, J.F.; Neyman, K.M.; Mayer, M.; Noertemann, F.; Gates, B.C.; Roesch, N.

    2000-03-21

    The interactions of Os{sub 4}, Os{sub 5}, and Os{sub 5}C clusters with various sites of a MgO(001) support were investigated theoretically with the aid of a scalar-relativistic density functional cluster model method. Adsorption geometries of C{sub 4{upsilon}} clusters centered above a magnesium cation and the Os atoms oriented either to the nearest surface oxygen anions (A) or between them (B) were considered. The influence of surface V{sub s} and V{sub s}{sup 2{minus}} defects on the adsorption of the clusters was also investigated. The calculated base Os-Os distances in supported Os{sub 5} and Os{sub 5}C square-pyramidal clusters are at most 0.1 {angstrom} longer (2.5--2.6{angstrom}) than the values calculated for the corresponding free osmium cluster but about 0.4{angstrom} (or more) shorter than the values determined by EXAFS spectroscopy for MgO-powder-supported clusters formed by decarbonylation of [Os{sub 5}C(CO){sub 14}]{sup 2{minus}} and shown to retains the Os{sub 5}C frame. The experimental Os-Os distances characterizing the supported clusters are close to the experimental and calculated bond lengths for coordinatively saturated osmium carbonyl clusters; the result favors the suggestion that the supported clusters characterized by EXAFS spectroscopy were not entirely ligand-free. The models reported here are inferred to be too simplified to capture all the pertinent structural details of MgO-powder-supported osmium clusters, but they are sufficient to indicate a significant role of defect sites in the adsorption of supported osmium clusters and, the authors infer, other transition metal clusters.

  19. Osmium and neodymium isotopic constraints on the temporal and spatial evolution of Siberian flood basalt sources

    USGS Publications Warehouse

    Horan, M.F.; Walker, R.J.; Fedorenko, V.A.; Czamanske, G.K.

    1995-01-01

    Picrites from the Gudchikhinsky suite, the oldest rocks examined, have ??Os of +5.3 to +6.1 and ??Nd of +3.7 to +4.0. The osmium and neodymium isotopic compositions of these rocks are similar to some modern ocean-island basalts (OIB), consistent with their derivation from an mantle plume. Picrites from the stratigraphically higher Tuklonsky suite have similar ??Os of +3.4 to +6.5, but ??Nd of -0.9 to -2.6. The similar ??Os, but lower ??Nd , suggest that some magmas from the same OIB-type, mantle source were contaminated by lithospheric components. A differentiated ankaramite flow, associated with the top of the stratigraphically higher Morongovsky suite, has ??Os of +9.8 to +10.2 and ??Nd of +1.3 to +1.4. The higher ??Os may indicate that the plume source was heterogeneous with respect to osmium isotopic composition, consistent with osmium isotopic measurements in rocks from other plume sources. Mg-rich, alkaline rocks (meymechites) from the Guli area that erupted much nearer the end of the flood-basalt event have ??Os of -1.2 to -2.6 and ??Nd of +3.7 to +4.9. These rocks were probably produced by low degrees of partial melting of mantle after the main stages of flood-basalt production. -from Authors

  20. Biological properties of novel ruthenium- and osmium-nitrosyl complexes with azole heterocycles.

    PubMed

    Novak, Maria S; Büchel, Gabriel E; Keppler, Bernhard K; Jakupec, Michael A

    2016-06-01

    Since the discovery that nitric oxide (NO) is a physiologically relevant molecule, there has been great interest in the use of metal nitrosyl compounds as antitumor pharmaceuticals. Particularly interesting are those complexes which can deliver NO to biological targets. Ruthenium- and osmium-based compounds offer lower toxicity compared to other metals and show different mechanisms of action as well as different spectra of activity compared to platinum-based drugs. Novel ruthenium- and osmium-nitrosyl complexes with azole heterocycles were studied to elucidate their cytotoxicity and possible interactions with DNA. Apoptosis induction, changes of mitochondrial transmembrane potential and possible formation of reactive oxygen species were investigated as indicators of NO-mediated damage by flow cytometry. Results suggest that ruthenium- and osmium-nitrosyl complexes with the general formula (indazolium)[cis/trans-MCl4(NO)(1H-indazole)] have pronounced cytotoxic potency in cancer cell lines. Especially the more potent ruthenium complexes strongly induce apoptosis associated with depolarization of mitochondrial membranes, and elevated reactive oxygen species levels. Furthermore, a slight yet not unequivocal trend to accumulation of intracellular cyclic guanosine monophosphate attributable to NO-mediated effects was observed. PMID:26961253

  1. Glycosaminoglycans in the rat aorta. Ultrastructural localization with toluidine blue O and osmium--ferrocyanide procedure.

    PubMed Central

    Coltoff-Schiller, B.; Goldfischer, S.

    1981-01-01

    Glycosaminoglycans (GAGs) have been implicated in the pathogenesis of sclerotic vascular disease. The localization of GAGs in the rat aorta was examined by two different ultrastructural cytochemical approaches. These procedures are believed to demonstrate 1) anionic sites, with fixatives that contain either toluidine blue or ruthenium red, both cationic dyes, and 2) polysaccharides, proteoglycans, and glycoproteins, with an osmium--ferrocyanide mixture that binds to vicinal diols. Both procedures stain a network of insoluble, 2--8-nm filaments that bridge collagen fibers, elastin, basement membranes, and plasma membranes. These structures resist digestion with chondroitinase ABC and appear to be identical to the filaments that have previously been demonstrated with ruthenium red. Focal 6--12-nm densities are present where filaments intersect. However, the large granules that are made visible with ruthenium red are not seen in toluidine blue or osmium--ferrocyanide preparations. A soluble and relatively amorphous component surrounds the tightly packed bundles of collagen in the media and is preserved and stained by toluidine blue and osmium--ferrocyanide mixtures. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 PMID:6172040

  2. Scaling Mesa Indium Phosphide DHBTs to Record Bandwidths

    NASA Astrophysics Data System (ADS)

    Lobisser, Evan

    Indium phosphide heterojunction bipolar transistors are able to achieve higher bandwidths at a given feature size than transistors in the Silicon material system for a given feature size. Indium phosphide bipolar transistors demonstrate higher breakdown voltages at a given bandwidth than both Si bipolars and field effect transistors in the InP material system. The high bandwidth of InP HBTs results from both intrinsic material parameters and bandgap engineering through epitaxial growth. The electron mobility in the InGaAs base and saturation velocity in the InP collector are both approximately three times higher than their counterparts in the SiGe material system. Resistance of the base can be made very low due to the large offset in the valence band between the InP emitter and the InGaAs base, which allows the base to be doped on the order of 1020 cm-3 with negligible reduction in emitter injection efficiency. This thesis deals with type-I, NPN dual-heterojunction bipolar transistors. The emitters are InP, and the base is InGaAs. There is a thin (˜ 10 nm) n-type InGaAs "setback" region, followed by a chirped superlattice InGaAs/InAlAs grade to the InP collector. The setback, grade, and collector are all lightly doped n-type. The emitter and collector are contacted through thin (˜ 5 nm) heavily doped n-type InGaAs layers to reduce contact resistivity. The primary focus of this work is increasing the bandwidth of InP HBTs through the proportional scaling of the device dimensions, both layer thicknesses and junction areas, as well as the reduction of the contact resistivities associated with the transistor. Essentially, all RC time constants and transit times must be reduced by a factor of two to double a transistor's bandwidth. Chapter 2 describes in detail the scaling laws and design principles for high frequency bipolar transistor design. A low-stress, blanket sputter deposited composite emitter metal process was developed. Refractory metal base contacts were

  3. Molecular beam epitaxy growth and characterization of dysprosium phosphide and dysprosium arsenide in gallium arsenide and gallium phosphide

    NASA Astrophysics Data System (ADS)

    Lee, Paul Piyawong

    The ability to grow thermally stable Schottky/ohmic contacts and buried, epitaxial metallic or semimetallic layers on semiconductors has many potential applications in novel device structures. Many rare earth group-V compounds with the sodium chloride structure possess the properties that make them potential candidates for stable contacts, buried layers, and other applications. In this work, two novel rare earth compounds, namely dysprosium phosphide (DyP) and dysprosium arsenide (DyAs) have been studied for high temperature ohmic/Schottky contacts to III-V semiconductors as well as for buried metal layers in semiconductor/metal/semiconductor structures. DyP and DyAs have been grown by molecular beam epitaxy on GaAs and GaP substrates. Both DyP and DyAs display metallic behavior and have room temperature resistivities of 8 x 10--5 and 1 x 10--4 Ocm, respectively. The electron concentrations for DyP and DyAs are about 4 x 1020 and 1 x 1021 cm--3, respectively. High quality DyP films as determined by XRD, AFM, and TEM can be achieved at a wide range of substrate temperatures (500°C to 600°C) with excess phosphorus pressure. Unlike most rare earth-group V compounds, DyP films are stable in air with no sign of oxidation. DyP films deposited on n-type GaAs and GaP exhibit Schottky behavior with room temperature barrier heights of 0.83 and 0.90 eV, respectively, with ideality factors close to unity and low reverse bias leakage current densities. These contacts are stable up to 250°C and 350°C for GaAs and GaP, respectively. DyAs films on the other hand, oxidize in air and display weak Schottky behavior on n-type GaAs. DyP has been grown as buried layers in both GaAs/DyP/GaAs and GaAs/DyP/GaP structures. Although high quality DyP layers have been achieved, the GaAs overlayers contain defects such as twins. The poor wetting of GaAs on DyP and the crystal symmetry between the two materials are responsible for the three-dimensional growth and the defects found in the Ga

  4. Cobalt phosphide nanowires: an efficient electrocatalyst for enzymeless hydrogen peroxide detection

    NASA Astrophysics Data System (ADS)

    Liu, Danni; Chen, Tao; Zhu, Wenxin; Cui, Liang; Asiri, Abdullah M.; Lu, Qun; Sun, Xuping

    2016-08-01

    In this letter, we demonstrate for the first time that cobalt phosphide nanowires (CoP NWs) exhibit remarkable catalytic activity toward electrochemical detection of hydrogen peroxide (H2O2). As an enzymeless H2O2 sensor, such CoP NWs show a fast amperometric response within 5 s and a low detection limit of 0.48 μM. In addition, this nonenzymatic sensor displays good selectivity, long-term stability and excellent reproducibility.

  5. Successful management of aluminium phosphide poisoning using intravenous lipid emulsion: Report of two cases

    PubMed Central

    Baruah, Udismita; Sahni, Ameeta; Sachdeva, Harish C.

    2015-01-01

    Aluminum phosphide (ALP) is a cheap, easily available agricultural pesticide which causes lethal poisoning by liberation of phosphine and inhibition of cytochrome c oxidase thereby leading to cellular hypoxia. Although there is no known specific antidote, clinical trials are still going on. We present here two cases of ALP poisoning who were successfully managed by treatment with lipid emulsion and intravenous magnesium sulfate. PMID:26816450

  6. Cobalt phosphide nanowires: an efficient electrocatalyst for enzymeless hydrogen peroxide detection.

    PubMed

    Liu, Danni; Chen, Tao; Zhu, Wenxin; Cui, Liang; Asiri, Abdullah M; Lu, Qun; Sun, Xuping

    2016-08-19

    In this letter, we demonstrate for the first time that cobalt phosphide nanowires (CoP NWs) exhibit remarkable catalytic activity toward electrochemical detection of hydrogen peroxide (H2O2). As an enzymeless H2O2 sensor, such CoP NWs show a fast amperometric response within 5 s and a low detection limit of 0.48 μM. In addition, this nonenzymatic sensor displays good selectivity, long-term stability and excellent reproducibility. PMID:27386800

  7. Ultra-fast mechanochemical synthesis of boron phosphides, BP and B12P2.

    PubMed

    Mukhanov, Vladimir A; Vrel, Dominique; Sokolov, Petr S; Le Godec, Yann; Solozhenko, Vladimir L

    2016-06-21

    Here we propose a new approach to the synthesis of single-phase boron phosphides (BP and B12P2) by mechanochemical reactions between boron phosphate and magnesium/magnesium diboride in the presence of an inert diluent (sodium chloride). The proposed method is characterized by the simplicity of implementation, high efficiency, low cost of the product, and good perspectives for large-scale production. PMID:27157207

  8. Hepatotoxicity due to zinc phosphide poisoning in two patients: role of N-acetylcysteine.

    PubMed

    Oghabian, Zohreh; Afshar, Arefeh; Rahimi, Hamid Reza

    2016-08-01

    Zinc phosphide (Zn3P2/ZnP) is used as a rodenticide. The most common signs of toxicity are nausea, vomiting, hypotension, and metabolic acidosis; patients presenting such signs are referred to the emergency department (ED) of the hospitals. Therefore, this study aimed to report two cases of hepatotoxicity following accidental and intentional ZnP poisoning and successful management with N-acetylcysteine (NAC). PMID:27525081

  9. Analysis of uranium-bearing Fe-phosphide from a submerged arc furnace for phosphorus production

    NASA Astrophysics Data System (ADS)

    Voncken, J. H. L.; Scheepers, E.; Yang, Y.

    2006-10-01

    During a study on the Fe-phosphide phase formed during phosphorus production in a submerged arc furnace, a sample of ferrophosphorus was found which contains a so far unknown uranium-bearing Fe-phosphide. Uranium, as well as other trace metals like Mn, V, Cr, Ni, Zr, originates from the apatite ore used. Ti originates partly from the silica and coke used in the reduction process, but mainly from the clay used to produce ore pellets. In this paper the ferrophosphorus is described with respect to composition and crystalline compounds present. The crystallization sequence is discussed with respect to the FeP-phase diagram. The main phases found in the ferrophosphorus are FeP and Fe2P. With respect to trace and minor metals, it is observed that Si preferably enters the FeP-phase, whereas Ti, V, Cr, Mn and Ni preferably enter the Fe2P-phase, which is an analogue of the mineral barringerite. This study gives some insight into the behavior of impurities during crystallization of an iron-rich Fe-phosphide melt. The uranium-bearing phase has an overall Me2P-stoichiometry (Fe1.59, Ti0.06, V0.03, Cr0.02, Mn0.06, Ni0.02, U0.15, Zr0.09)2.02 (P0.96, Si0.02)0.98. An X-ray diffraction pattern of this phase is given for identification purposes.

  10. Ingestion of gallium phosphide nanowires has no adverse effect on Drosophila tissue function

    NASA Astrophysics Data System (ADS)

    Adolfsson, Karl; Schneider, Martina; Hammarin, Greger; Häcker, Udo; Prinz, Christelle N.

    2013-07-01

    Engineered nanoparticles have been under increasing scrutiny in recent years. High aspect ratio nanoparticles such as carbon nanotubes and nanowires have raised safety concerns due to their geometrical similarity to asbestos fibers. III-V epitaxial semiconductor nanowires are expected to be utilized in devices such as LEDs and solar cells and will thus be available to the public. In addition, clean-room staff fabricating and characterizing the nanowires are at risk of exposure, emphasizing the importance of investigating their possible toxicity. Here we investigated the effects of gallium phosphide nanowires on the fruit fly Drosophila melanogaster. Drosophila larvae and/or adults were exposed to gallium phosphide nanowires by ingestion with food. The toxicity and tissue interaction of the nanowires was evaluated by investigating tissue distribution, activation of immune response, genome-wide gene expression, life span, fecundity and somatic mutation rates. Our results show that gallium phosphide nanowires applied through the diet are not taken up into Drosophila tissues, do not elicit a measurable immune response or changes in genome-wide gene expression and do not significantly affect life span or somatic mutation rate.

  11. Evaluation of Metal Phosphide Nanocrystals as Anode Materials for Na-ion Batteries.

    PubMed

    Walter, Marc; Bodnarchuk, Maryna I; Kravchyk, Kostiantyn V; Kovalenko, Maksym V

    2015-01-01

    Sodium-ion batteries (SIBs) are potential low-cost alternatives to lithium-ion batteries (LIBs) because of the much greater natural abundance of sodium salts. However, developing high-performance electrode materials for SIBs is a challenging task, especially due to the ∼50% larger ionic radius of the Na(+) ion compared to Li(+), leading to vastly different electrochemical behavior. Metal phosphides such as FeP, CoP, NiP(2), and CuP(2) remain unexplored as electrode materials for SIBs, despite their high theoretical charge storage capacities of 900-1300 mAh g(-1). Here we report on the synthesis of metal phosphide nanocrystals (NCs) and discuss their electrochemical properties as anode materials for SIBs, as well as for LIBs. We also compare the electrochemical characteristics of phosphides with their corresponding sulfides, using the environmentally benign iron compounds, FeP and FeS(2), as a case study. We show that despite the appealing initial charge storage capacities of up to 1200 mAh g(-1), enabled by effective nanosizing of the active electrode materials, further work toward optimization of the electrode/electrolyte pair is needed to improve the electrochemical performance upon cycling. PMID:26842319

  12. Features of the band structure for semiconducting iron, ruthenium, and osmium monosilicides

    SciTech Connect

    Shaposhnikov, V. L. Migas, D. B.; Borisenko, V. E.; Dorozhkin, N. N.

    2009-02-15

    The pseudopotential method has been used to optimize the crystal lattice and calculate the energy band spectra for iron, ruthenium and, osmium monosilicides. It is found that all these compounds are indirect-gap semiconductors with band gaps of 0.17, 0.22, and 0.50 eV (FeSi, RuSi, and OsSi, respectively). A distinctive feature of their band structure is the 'loop of extrema' both in the valence and conduction bands near the center of the cubic Brillouin zone.

  13. Easy To Synthesize, Robust Organo‐osmium Asymmetric Transfer Hydrogenation Catalysts

    PubMed Central

    Coverdale, James P. C.; Sanchez‐Cano, Carlos; Clarkson, Guy J.; Soni, Rina

    2015-01-01

    Abstract Asymmetric transfer hydrogenation (ATH) is an important process in organic synthesis for which the Noyori‐type RuII catalysts [(arene)Ru(Tsdiamine)] are now well established and widely used. We now demonstrate for the first time the catalytic activity of the osmium analogues. X‐ray crystal structures of the 16‐electron OsII catalysts are almost identical to those of RuII. Intriguingly the precursor complex was isolated as a dichlorido complex with a monodentate amine ligand. The OsII catalysts are readily synthesised (within 1 h) and exhibit excellent enantioselectivity in ATH reactions of ketones. PMID:25853228

  14. Photocurrent generation from thylakoid membranes on osmium-redox-polymer-modified electrodes.

    PubMed

    Hamidi, Hassan; Hasan, Kamrul; Emek, Sinan Cem; Dilgin, Yusuf; Åkerlund, Hans-Erik; Albertsson, Per-Åke; Leech, Dónal; Gorton, Lo

    2015-03-01

    Thylakoid membranes (TMs) are uniquely suited for photosynthesis owing to their distinctive structure and composition. Substantial efforts have been directed towards use of isolated photosynthetic reaction centers (PRCs) for solar energy harvesting, however, few studies investigate the communication between whole TMs and electrode surfaces, due to their complex structure. Here we report on a promising approach to generate photosynthesis-derived bioelectricity upon illumination of TMs wired with an osmium-redox-polymer modified graphite electrode, and generate a photocurrent density of 42.4 μA cm(-2). PMID:25703722

  15. Structure and reactivity of distanna[2]metallocenophanes of ruthenium and osmium.

    PubMed

    Braunschweig, Holger; Hupp, Florian; Kramer, Thomas; Mager, Julian

    2013-08-01

    We report the molecular structures of 1,1'-dilithiometallocenes of ruthenium and osmium. These compounds served as precursors for the synthesis and subsequent structural characterization of the first [2]osmocenophanes with disilane and distannane bridges, as well as of a distanna[2]ruthenocenophane. In addition, the insertion of sulfur and selenium into the Sn-Sn bridges was studied and it was observed that the presence of the Lewis base pmdta (N,N,N',N″,N″-pentamethyldiethylenetriamine) dramatically accelerates the reaction. PMID:23876041

  16. Osmium(II) polypyridyl polyarginine conjugate as a probe for live cell imaging; a comparison of uptake, localization and cytotoxicity with its ruthenium(II) analogue.

    PubMed

    Byrne, Aisling; Dolan, Ciarán; Moriarty, Roisin D; Martin, Aaron; Neugebauer, Ute; Forster, Robert J; Davies, Anthony; Volkov, Yuri; Keyes, Tia E

    2015-08-28

    A first investigation into the application of a luminescent osmium(ii) bipyridine complex to live cell imaging is presented. Osmium(ii) (bis-2,2-bipyridyl)-2(4-carboxylphenyl) imidazo[4,5f][1,10]phenanthroline was prepared and conjugated to octaarginine, a cell penetrating peptide. The photophysics, cell uptake and cytotoxicity of this osmium complex conjugate were performed and compared with its ruthenium analogue. Cell uptake and distribution of both ruthenium and osmium conjugates were very similar with rapid transmembrane transport of the osmium probe (complete within approx. 20 min) and dispersion throughout the cytoplasm and organelles. The near-infrared (NIR) emission of the osmium complex (λmax 726 nm) coincides well with the biological optical window and this facilitated luminescent and luminescence lifetime imaging of the cell which was well resolved from cell autofluorescence. The large Stokes shift of the emission also permitted resonance Raman mapping of the dye within CHO cells. Rather surprisingly, the osmium conjugate exhibited very low cytotoxicity when incubated both in the dark and under visible irradiation. This was attributed to the remarkable stability of this complex which was reflected by the complete absence of photo-bleaching of the complex even under extended continuous irradiation. In addition, when compared to its ruthenium analogue its luminescence was short-lived in water therefore rendering it insensitive to O2. PMID:26197944

  17. Evaluation of Potential Oxidative Stress in Egyptian Patients with Acute Zinc Phosphide Poisoning and the Role of Vitamin C

    PubMed Central

    Sagah, Ghada A.; Oreby, Merfat M.; El-Gharbawy, Rehab M.; Ahmed Fathy, Amal S.

    2015-01-01

    Objective To evaluate potential oxidative stress in patients with acute phosphide poisoning and the effect of vitamin C. Methods Participants were females and divided into three groups; group I: healthy volunteers group II: healthy volunteers received vitamin C, group III: patients with acute phosphide poisoning received the supportive and symptomatic treatment and group IV: patients with acute phosphide poisoning received the supportive and symptomatic treatment in addition to vitamin C. All the participants were subjected to thorough history, clinical examination, ECG and laboratory investigations were carried on collected blood and gastric lavage samples on admission. Blood samples were divided into two parts, one for measurement of routine investigations and the second part was used for evaluation of malondialdehyde and total thiol levels before and after receiving the treatment regimen. Results Most of the cases in this study were among the age group of 15–25 years, females, single, secondary school education, from rural areas and suicidal. All vital signs were within normal range and the most common complaint was vomiting and abdominal pain. All cases in this study showed normal routine investigations. The mean MDA levels after receiving treatment decreased significantly in groups II and IV. The mean total thiol levels increased significantly after receiving treatment in groups II and IV. Conclusion It can be concluded that vitamin C has a potential benefit due to its antioxidant property on zinc phosphide induced-oxidative stress in acute zinc phosphide poisoned patients. PMID:26715917

  18. Enhanced multiplexing in mass cytometry using osmium and ruthenium tetroxide species.

    PubMed

    Catena, Raúl; Özcan, Alaz; Zivanovic, Nevena; Bodenmiller, Bernd

    2016-05-01

    Mass cytometry facilitates high-dimensional, quantitative, single-cell analysis. The method for sample multiplexing in mass cytometry, called mass-tag cellular barcoding (MCB), relies on the covalent reaction of bifunctional metal chelators with intracellular proteins. Here, we describe the use of osmium and ruthenium tetroxides (OsO4 and RuO4 ) that bind covalently with fatty acids in the cellular membranes and aromatic amino acids in proteins. Both OsO4 and RuO4 rapidly reacted and allowed for MCB with live cells, crosslinked cells, and permeabilized cells. Given the covalent nature of the labeling reaction, isotope leaching was not observed. OsO4 and RuO4 were used in a 20-sample barcoding protocol together with palladium isotopes. As mass channels occupied by osmium and ruthenium are not used for antibody detection the number of masses effectively utilized in a single experiment is expanded. OsO4 and RuO4 can therefore be used as MCB reagents for a wide range of mass cytometry workflows. © 2016 International Society for Advancement of Cytometry. PMID:27018769

  19. Aerobic Oxidation of an Osmium(III) N-Hydroxyguanidine Complex To Give Nitric Oxide.

    PubMed

    Xiang, Jing; Wang, Qian; Yiu, Shek-Man; Man, Wai-Lun; Kwong, Hoi-Ki; Lau, Tai-Chu

    2016-05-16

    The aerobic oxidation of the N-hydroxyguanidinum moiety of N-hydroxyarginine to NO is a key step in the biosynthesis of NO by the enzyme nitric oxide synthase (NOS). So far, there is no chemical system that can efficiently carry out similar aerobic oxidation to give NO. We report here the synthesis and X-ray crystal structure of an osmium(III) N-hydroxyguanidine complex, mer-[Os(III){NH═C(NH2)(NHOH)}(L)(CN)3](-) (OsGOH, HL = 2-(2-hydroxyphenyl)benzoxazole), which to the best of our knowledge is the first example of a transition metal N-hydroxyguanidine complex. More significantly, this complex readily undergoes aerobic oxidation at ambient conditions to generate NO. The oxidation is pH-dependent; at pH 6.8, fac-[Os(NO)(L)(CN)3](-) is formed in which the NO produced is bound to the osmium center. On the other hand, at pH 12, aerobic oxidation of OsGOH results in the formation of the ureato complex [Os(III)(NHCONH2)(L)(CN)3](2-) and free NO. Mechanisms for this aerobic oxidation at different pH values are proposed. PMID:27135258

  20. Osmium-Based Pyrimidine Contrast Tags for Enhanced Nanopore-Based DNA Base Discrimination.

    PubMed

    Henley, Robert Y; Vazquez-Pagan, Ana G; Johnson, Michael; Kanavarioti, Anastassia; Wanunu, Meni

    2015-01-01

    Nanopores are a promising platform in next generation DNA sequencing. In this platform, an individual DNA strand is threaded into nanopore using an electric field, and enzyme-based ratcheting is used to move the strand through the detector. During this process the residual ion current through the pore is measured, which exhibits unique levels for different base combinations inside the pore. While this approach has shown great promise, accuracy is not optimal because the four bases are chemically comparable to one another, leading to small differences in current obstruction. Nucleobase-specific chemical tagging can be a viable approach to enhancing the contrast between different bases in the sequence. Herein we show that covalent modification of one or both of the pyrimidine bases by an osmium bipyridine complex leads to measureable differences in the blockade amplitudes of DNA molecules. We qualitatively determine the degree of osmylation of a DNA strand by passing it through a solid-state nanopore, and are thus able to gauge T and C base content. In addition, we show that osmium bipyridine reacts with dsDNA, leading to substantially different current blockade levels than exhibited for bare dsDNA. This work serves as a proof of principle for nanopore sequencing and mapping via base-specific DNA osmylation. PMID:26657869

  1. Detection of a meteoritic component in ivory coast tektites with rhenium-osmium isotopes.

    PubMed

    Koeberl, C; Shirey, S B

    1993-07-30

    Measurement of rhenium (Re) and osmium (Os) concentrations and Os isotopic compositions in Ivory Coast tektites (natural glasses with upper crustal compositions that are ejected great distances during meteorite impact) and rocks from the inferred source crater, Lake Bosumtwi, Ghana, show that these tektites incorporate about 0.6 percent of a meteoritic component. Analysis of elemental abundances of noble metals alone gives equivocal results in the detection of meteoritic components because the target rocks already have relatively large amounts of noble metals. The Re-Os system is ideally suited for the study of meteorite impacts on old continental crust for three reasons. (i) The isotopic compositions of the target rocks and the meteoritic impactor are significantly different. (ii) Closed-system mixing of target rocks and meteorites is linear on Re-Os isochron diagrams, which thus permits identification of the loss of Re or Os. (iii) Osmium isotopic compositions are not likely to be altered during meteorite impact even if Re and Os are lost. PMID:17758170

  2. Detection of a meteoritic component in Ivory Coast tektites with rhenium-osmium isotopes

    NASA Astrophysics Data System (ADS)

    Koeberl, Christian; Shirey, Steven B.

    1993-07-01

    Measurement of rhenium (Re) and osmium (Os) concentrations and Os isotopic compositions in Ivory Coast tektites (natural glasses with upper crustal compositions that are ejected great distances during meteorite impact) and rocks from the inferred source crater, Lake Bosumtwi, Ghana, show that these tektites incorporate about 0.6 percent of a meteoritic component. Analysis of elemental abundances of noble metals alone gives equivocal results in the detection of meteoritic components because the target rocks already have relatively large amounts of noble metals. The Re-Os system is ideally suited for the study of meteorite impacts on old continental crust for three reasons. The isotopic compositions of the target rocks and the meteoritic impactor are significantly different. Closed-system mixing of target rocks and meteorites is linear on Re-Os isochron diagrams, which thus permits identification of the loss of Re or Os. Osmium isotopic compositions are not likely to be altered during meteorite impact even if Re and Os are lost.

  3. Osmium ferricyanide fixation improves microfilament preservation and membrane visualization in a variety of animal cell types.

    PubMed

    McDonald, K

    1984-02-01

    Using a fixation formula which includes adding potassium ferricyanide (K3Fe(CN)6) to the osmium step and an en bloc aqueous uranyl acetate step before dehydration we have looked at cells from mammals, birds, amphibia, algae, and higher plants and we have collaborated in fixing cells of teleost fish. In every cell type except the algae and higher plants the final EM image was improved by the OsFeCN-uranium method. The most common improvement was an increase in the membrane contrast but more significantly, some cells show improved preservation of microfilaments. We conclude that the OsFeCN adds contrast to all classes of membrane and does not destroy microfilaments to the extent that osmium alone does. Adding uranyl acetate to the cells may protect delicate filamentous structures from collapse during dehydration and embedding. We have preliminary evidence in PtK1 cells that addition of tannic acid after OsFeCN may function in a similar manner. This method is recommended for any animal cell type where improved visualization of membranes and filaments is required. PMID:6539826

  4. Investigation of Luminescence Characteristics of Osmium(II) Complexes in the Presence of Heparin Polyanions

    PubMed Central

    Xie, Yixi; Lei, Yu; Shah, Shalini; Wu, Hao; Wu, Jian; Megehee, Elise; Wang, Enju

    2013-01-01

    The luminescence characteristics of six osmium carbonyl complexes with phenanthroline (phen) or bipyridine (bpy) and pyridine (py), 4-phenylpyridine (4-phpy), or triphenylphosphine (PPh3) complexes in the presence of polyanion heparin were studied in both ethanol and aqueous solutions. The influence of heparin on the luminescence of the complexes is heavily dependent on the type of ligands in the complexes and the solvent used. In the ethanol solutions, the heparin solution enhanced the luminescence of the five osmium complexes, with the strongest enhancement to the 4-phenylpyridine complexes; linear curves were obtained in the luminescence enhancement ratio (F/F0) versus the heparin concentration range of 1–40 μg/mL. In aqueous solutions, heparin quenching of the complexes was more significant; a linear quenching curve was obtained with [Os(phen)2CO(PPh3)](PF6)2 in the lower concentration range of 1–12 μg/mL. The interaction of these complexes with heparin in the solutions is discussed. The complexes are shown to be successful in the fast and sensitive detection of heparin in commercial injectable samples. PMID:23956748

  5. Osmium-Based Pyrimidine Contrast Tags for Enhanced Nanopore-Based DNA Base Discrimination

    PubMed Central

    Henley, Robert Y.; Vazquez-Pagan, Ana G.; Johnson, Michael; Kanavarioti, Anastassia; Wanunu, Meni

    2015-01-01

    Nanopores are a promising platform in next generation DNA sequencing. In this platform, an individual DNA strand is threaded into nanopore using an electric field, and enzyme-based ratcheting is used to move the strand through the detector. During this process the residual ion current through the pore is measured, which exhibits unique levels for different base combinations inside the pore. While this approach has shown great promise, accuracy is not optimal because the four bases are chemically comparable to one another, leading to small differences in current obstruction. Nucleobase-specific chemical tagging can be a viable approach to enhancing the contrast between different bases in the sequence. Herein we show that covalent modification of one or both of the pyrimidine bases by an osmium bipyridine complex leads to measureable differences in the blockade amplitudes of DNA molecules. We qualitatively determine the degree of osmylation of a DNA strand by passing it through a solid-state nanopore, and are thus able to gauge T and C base content. In addition, we show that osmium bipyridine reacts with dsDNA, leading to substantially different current blockade levels than exhibited for bare dsDNA. This work serves as a proof of principle for nanopore sequencing and mapping via base-specific DNA osmylation. PMID:26657869

  6. Magneto-Transport Studies of Molecular Beam Epitaxial Grown Osmium Silicides

    NASA Astrophysics Data System (ADS)

    Cottier, Ryan; Zhao, Wei; Amir, Fatima; Hossain, Khalid; Anibou, Noureddine; Donner, Wolfgang; Golding, Terry

    2006-03-01

    Semiconducting transition metal silicides present a possible solution to on-chip integration of optical and electronic Si-based circuitry. Two phases of osmium silicide (OsSi2 and Os2Si3) are predicted to have promising optical characteristics but require additional development to fully determine their feasibility for high-quality devices. This study has been motivated by reports that OsSi2 has a bandgap between 1.4--1.8eV [1, 2] and Os2Si3 may have a direct bandgap of 0.95 eV [3] or 2.3 eV [1]. In this paper we will present temperature dependent (20 < T < 300 K) magneto Hall measurements of molecular beam epitaxial grown osmium silicide thin films. Os and Si were coevaporated onto Si(100) substrates at varying growth rates and temperatures. XRD was performed in order to identify the silicide phases present. We will discuss our results in relation to the known phase diagrams and our growth parameters. [1] L. Schellenberg et al., J. Less-Common Met. 144, 341 (1988). [2] K. Mason and G. Müller-Vogt, J. Appl. Phys. 63, 34 (1983). [3] A. B. Filonov et al., Phys. Rev. B 60(24), 16494 (1999).

  7. Short review of high-pressure crystal growth and magnetic and electrical properties of solid-state osmium oxides

    NASA Astrophysics Data System (ADS)

    Yamaura, Kazunari

    2016-04-01

    High-pressure crystal growth and synthesis of selected solid-state osmium oxides, many of which are perovskite-related types, are briefly reviewed, and their magnetic and electrical properties are introduced. Crystals of the osmium oxides, including NaOsO3, LiOsO3, and Na2OsO4, were successfully grown under high-pressure and high-temperature conditions at 6 GPa in the presence of an appropriate amount of flux in a belt-type apparatus. The unexpected discovery of a magnetic metal-insulator transition in NaOsO3, a ferroelectric-like transition in LiOsO3, and high-temperature ferrimagnetism driven by a local structural distortion in Ca2FeOsO6 may represent unique features of the osmium oxides. The high-pressure and high-temperature synthesis and crystal growth has played a central role in the development of solid-state osmium oxides and the elucidation of their magnetic and electronic properties toward possible use in multifunctional devices.

  8. Three-Dimensional Structural Analysis of MgO-Supported Osmium Clusters by Electron Microscopy with Single-Atom Sensitivity

    SciTech Connect

    Aydin, C.; Kulkarni, Apoorva; Chi, Miaofang; Browning, Nigel D.; Gates, Bruce C.

    2013-05-10

    Size, shape, nuclearity: Aberration-corrected scanning transmission electron microscopy was used to determine the 3D structures of MgO-supported Os3, Os4, Os5, and Os10 clusters, which have structures nearly matching those of osmium carbonyl compounds with known crystal structures. The samples are among the best-defined supported catalysts.

  9. A New Lifshitz Transition and the Equation of State of Osmium

    SciTech Connect

    Occelli, F; Aracne, C M; Teter, D M; Hanfland, M; Canny, B; Couzinet, B; Chervin, J; Badro, J; Farber, D L

    2003-11-05

    We have measured the equation of state (EoS) of osmium to 75 GPa under hydrostatic conditions at room temperature using angle dispersive x-ray diffraction. A least-squares fit of the data using a third order Birch-Murnaghan EoS yields K{sub 0} = 411 {+-} 6 GPa and K'{sub 0} = 4.0 {+-} 0.2, showing osmium is in fact more compressible than diamond. Most importantly, we have documented an anomaly in the compressibility at 20.3 GPa associated with a large discontinuity in the first pressure derivative of the c/a ratio. This discontinuity likely arises from the collapse of the small hole-ellipsoid in the Fermi surface near the L point. There has been much interest in the possibility of a Lifshitz [1] or electronic topological transition (ETT) in zinc at high-pressure near 10 GPa. Interestingly, while the experimental data remain somewhat ambiguous [2-5], most simulations suggest the ETT exists in this pressure range [6-8]. Recently, Steinle-Neumann et al. [8] have shown that the transition arises from changes in the band structure near the high-symmetry point K where three bands cross the Fermi surface upon compression. Thus one might expect that other hcp metals should exhibit similar phenomena. The hcp 4d and 5d transition elements Re, Os and Ru are known to be among the densest and stiffest metals [9,10] suggesting that these might in fact be poor candidates in which to look for such effects. In osmium however, experimental and theoretical results [11,12] have shown the existence of small local maxima in the band structure just above the Fermi energy near the high-symmetry point L on the zone boundary [11]. These structures might potentially fall below the Fermi energy upon compression and give rise to an ETT. Osmium is of further interest as recent EoS measurements by Cynn et al. [13] have suggested that Os (K{sub 0} = 462 GPa and K'{sub 0} = 2.4) has the lowest known compressibility, lower even than diamond (K{sub 0} = 446 GPa and K'{sub 0} = 3) [14]. This

  10. Osmium(0) nanoclusters stabilized by zeolite framework; highly active catalyst in the aerobic oxidation of alcohols under mild conditions.

    PubMed

    Zahmakiran, Mehmet; Akbayrak, Serdar; Kodaira, Tetsuya; Ozkar, Saim

    2010-08-28

    Osmium(0) nanoclusters stabilized by zeolite-Y framework were reproducibly prepared by a simple two step procedure involving the incorporation of osmium(III) cations into the zeolite matrix by ion-exchange, followed by their reduction within the cavities of zeolite with sodium borohydride in aqueous solution all at room temperature. The composition and morphology of osmium(0) nanoclusters stabilized by zeolite framework, as well as the integrity and crystallinity of the host material were investigated by using ICP-OES, XRD, XPS, SEM, TEM, HRTEM, TEM/EDX, mid-IR, far-IR spectroscopies, and N(2)-adsorption/desorption technique. The results of the multiprong analysis reveal the formation of osmium(0) nanoclusters within the cavities of zeolite-Y without causing alteration in the framework lattice, formation of mesopores, or loss in the crystallinity of the host material. More importantly, far-IR studies showed that after the reduction of Os(3+) cations by sodium borohydride the Na(+) cations reoccupy their authentic cation sites restoring the integrity of zeolite-Y. The catalytic activity of osmium(0) nanoclusters stabilized by zeolite framework was tested in the aerobic oxidation of activated, unactivated and heteroatom containing alcohols to carbonyl compounds and was found to provide high activity and selectivity even under mild conditions (80 degrees C and 1 atm O(2) or air). Moreover, they were found to be stable enough to be isolated and bottled as solid material, which can be reused as active catalyst under the identical conditions of the first run. PMID:20614055

  11. Measurement of charge-carrier concentration in indium phosphide by means of an electrolyte-semiconductor contact

    SciTech Connect

    Asanov, O.M.; Gaman, V.I.; Zorkal'tseva, N.N.; Korableva, T.V.; Petrova, N.G.

    1987-11-01

    An electrolyte-semiconductor contact is used to study the conductivity of epitaxial layers and single crystals of n-type indium phosphide obtained by gas transport. Some of the specimens were alloyed with tin and sulfur. The volt-farad characteristics are used to find the potentials of planar zones, which amount to 0.8-1.3 V for different electrolytes. Values of concentration of charge carriers calculated from measured values of capacitance of the electrolyte-indium-phosphide contact showed good agreement with measurements of the Hall effect on single crystals in the range 10/sup 16/-10/sup 18/ cm/sup -3/. The use of measurements of the capacitance of the electrolyte-semiconductor contact with simultaneous etching of a local region made it possible to study the electron distribution in epitaxial layers of indium phosphide.

  12. One-Step Synthesis of Self-Supported Nickel Phosphide Nanosheet Array Cathodes for Efficient Electrocatalytic Hydrogen Generation.

    PubMed

    Wang, Xiaoguang; Kolen'ko, Yury V; Bao, Xiao-Qing; Kovnir, Kirill; Liu, Lifeng

    2015-07-01

    Nickel phosphide is an emerging low-cost, earth-abundant catalyst that can efficiently reduce water to generate hydrogen. However, the synthesis of nickel phosphide catalysts usually involves multiple steps and is laborious. Herein, a convenient and straightforward approach to the synthesis of a three-dimensional (3D) self-supported biphasic Ni5 P4 -Ni2 P nanosheet (NS) array cathode is presented, which is obtained by direct phosphorization of commercially available nickel foam using phosphorus vapor. The synthesized 3D Ni5 P4 -Ni2 P-NS array cathode exhibits outstanding electrocatalytic activity and long-term durability toward the hydrogen evolution reaction (HER) in acidic medium. The fabrication procedure reported here is scalable, showing substantial promise for use in water electrolysis. More importantly, the approach can be readily extended to synthesize other self-supported transition metal phosphide HER cathodes. PMID:26032688

  13. Engineering absorption and blackbody radiation in the far-infrared with surface phonon polaritons on gallium phosphide

    SciTech Connect

    Streyer, W.; Law, S.; Rosenberg, A.; Wasserman, D.; Roberts, C.; Podolskiy, V. A.; Hoffman, A. J.

    2014-03-31

    We demonstrate excitation of surface phonon polaritons on patterned gallium phosphide surfaces. Control over the light-polariton coupling frequencies is demonstrated by changing the pattern periodicity and used to experimentally determine the gallium phosphide surface phonon polariton dispersion curve. Selective emission via out-coupling of thermally excited surface phonon polaritons is experimentally demonstrated. Samples are characterized experimentally by Fourier transform infrared reflection and emission spectroscopy, and modeled using finite element techniques and rigorous coupled wave analysis. The use of phonon resonances for control of emissivity and excitation of bound surface waves offers a potential tool for the exploration of long-wavelength Reststrahlen band frequencies.

  14. Correction: Unexpected higher stabilisation of two classical antiaromatic frameworks with a ruthenium fragment compared to the osmium counterpart: origin probed by DFT calculations.

    PubMed

    Wu, Jingjing; Hao, Yulei; An, Ke; Zhu, Jun

    2016-01-25

    Correction for 'Unexpected higher stabilisation of two classical antiaromatic frameworks with a ruthenium fragment compared to the osmium counterpart: origin probed by DFT calculations' by Jingjing Wu et al., Chem. Commun., 2016, 52, 272-275. PMID:26699929

  15. An approach to preparing porous and hollow metal phosphides with higher hydrodesulfurization activity

    SciTech Connect

    Song Limin; Zhang Shujuan; Wei Qingwu

    2011-06-15

    This paper describes an effective method for the synthesis of metal phosphides. Bulk and supported Ni{sub 2}P, Cu{sub 3}P, and CoP were prepared by thermal treatment of metal and the amorphous red phosphorus mixtures. Porous and hollow Ni{sub 2}P particles were also synthesized successfully using this method. The structural properties of these products are investigated using X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), inductively coupled plasma (ICP-AES) and X-ray photoemission spectroscopy (XPS). A rational mechanism was proposed for the selective formation of Ni{sub 2}P particles. In experimental conditions, the Ni{sub 2}P/SiO{sub 2} catalyst exhibits excellent hydrodesulfurization (HDS) activity for dibenzothiophene (DBT). - Graphical abstract: Bulk and supported Ni{sub 2}P, Cu{sub 3}P, and CoP were prepared by thermal treatment of their metal and amorphous red phosphorus mixtures. Porous and hollow Ni{sub 2}P particles were successfully synthesized by this method also. In the experimental condition, a Ni{sub 2}P/SiO{sub 2} catalyst exhibits excellent hydrodesulfurization activity for dibenzothiophene. Highlights: > A new synthetic route by heat treating mixtures of metal and red phosphorus in flowing N{sub 2} to prepare corresponding metal phosphides. > Porous and hollow Ni{sub 2}P particles may successfully be obtained using the route. > It is very easy to synthesize other bulk and supported metal phosphides using the mixing of bulk and supported metal and red phosphorus by the method. > The Ni{sub 2}P/SiO{sub 2} catalyst synthesized by the route shows a good HDS of dibenzothiophene. > Its operation is simple (only heat treating pure metal and red phosphorus), and the reaction time is short (only 0.5 h).

  16. Annealing behavior of the hydrogen-vacancy complex in bulk indium phosphide crystals

    SciTech Connect

    Ye, Q.; Wolk, J.A.; Bourret-Courchesne, E.D.; Bliss, D.F.

    1998-12-31

    In order to explain the effects of hydrogen on the electrical properties of bulk indium phosphide crystals, they have performed a series of high temperature annealing studies with both undoped and iron-doped indium phosphide crystals. The samples were annealed at 900 C for 6, 36, and 72 hours, respectively, under a phosphorus overpressure of five atmospheres. Samples were characterized at 10 K by Fourier transform infrared absorption spectroscopy which allowed us to measure the concentrations of both the Fe{sup 2+} and V{sub In}-H{sub 4} defects simultaneously. Undoped samples were further characterized by the Hall effect measurements. The authors find in the iron-doped samples that the [Fe{sup 2+}]/[Fe{sup 3+}] ratio decreases gradually with increasing annealing time, indicating a reduction in the number of donors in the samples. In the undoped samples, annealing leads to a reduction of the free electron concentration accompanied by an increase in the 77 K mobility. The increase of the sample`s mobility eliminates the possibility that the reduction of the free electron concentration is due to an increase in the concentration of the compensating acceptors. The explanation for the observed behavior in all samples is that hydrogen acts as a donor and it diffuses out of the crystal during the annealing process. Based on the experimental data, they propose a calibration equation of [V{sub In}-H{sub 4}] = 4.2 {times} 10{sup 16} cm{sup {minus}1} {times} Absorbance (cm{sup {minus}1}) which is used to correlate the hydrogen-vacancy complex concentrations with the changes of the V{sub In}-H{sub 4} absorption peak in both the iron-doped and the undoped samples. Their results confirm the donor nature of the hydrogen-vacancy complex and provide strong evidence regarding the reduction mechanism of free carrier concentrations in bulk indium phosphide crystals during high temperature annealing under a phosphorus atmosphere.

  17. Essential elucidation for preparation of supported nickel phosphide upon nickel phosphate precursor

    SciTech Connect

    Liu, Xuguang; Xu, Lei; Zhang, Baoquan

    2014-04-01

    Preparation of supported nickel phosphide (Ni{sub 2}P) depends on nickel phosphate precursor, generally related to its chemical composition and supports. Study of this dependence is essential and meaningful for the preparation of supported Ni{sub 2}P with excellent catalytic activity. The chemical nature of nickel phosphate precursor is revealed by Raman and UV–vis spectra. It is found that initial P/Ni mole ratio ≥0.8 prohibits the Ni-O-Ni bridge bonding (i.e., nickel oxide). This chemical bonding will not result in Ni{sub 2}P structure, verified by XRD characterization results. The alumina (namely, γ-Al{sub 2}O{sub 3}, θ-Al{sub 2}O{sub 3}, or α-Al{sub 2}O{sub 3}) with distinct physiochemical properties also results in diverse chemical nature of nickel phosphate, and then different nickel phosphides. The influence of alumina support on producing Ni{sub 2}P was explained by the theory of surface energy heterogeneity, calculated by the NLDFT method based on N{sub 2}-sorption isotherm. The uniform surface energy of α-Al{sub 2}O{sub 3} results only in the nickel phosphosate precursor and thus the Ni{sub 2}P phase. - Graphical abstract: Surface energy heterogeneity in alumina (namely α-Al{sub 2}O{sub 3}, θ-Al{sub 2}O{sub 3}, and γ-Al{sub 2}O{sub 3}) supported multi-oxidic precursors with different reducibilities and thus diverse nickel phosphides (i.e., Ni{sub 3}P, Ni{sub 12}P{sub 5}, Ni{sub 2}P). - Highlights: • Preparing pure Ni{sub 2}P. • Elucidating nickel phosphate precursor. • Associating with surface energy.

  18. Comparative radiation resistance, temperature dependence and performance of diffused junction indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Swartz, C. K.; Hart, R. E., Jr.; Ghandhi, S. K.; Borrego, J. M.

    1987-01-01

    Indium phosphide solar cells whose p-n junctions were processed by the open tube capped diffusion and by the closed tube uncapped diffusion of sulfur into Czochralski-grown p-type substrates are compared. Differences found in radiation resistance were attributed to the effects of increased base dopant concentration. Both sets of cells showed superior radiation resistance to that of gallium arsenide cells, in agreement with previous results. No correlation was, however, found between the open-circuit voltage and the temperature dependence of the maximum power.

  19. Theoretical Investigations on the Elastic and Thermodynamic Properties of Rhenium Phosphide

    NASA Astrophysics Data System (ADS)

    Wei, Qun; Yan, Haiyan; Zhu, Xuanmin; Lin, Zhengzhe; Yao, Ronghui

    2016-01-01

    Structural, mechanical, and electronic properties of orthorhombic rhenium phosphide (Re2P) are systematically investigated by using first principles calculations. The elastic constants and anisotropy of elastic properties are obtained. The metallic character of Re2P is demonstrated by density of state calculations. The quasi-harmonic Debye model is applied to the study of the thermodynamic properties. The thermal expansion, heat capacities, and Grüneisen parameter on the temperature and pressure have been determined as a function of temperature and pressure in the pressure range from 0 to 100 GPa and the temperature range from 0 to 1600 K.

  20. An efficient bifunctional electrocatalyst for water splitting based on cobalt phosphide

    NASA Astrophysics Data System (ADS)

    Yang, Libin; Qi, Honglan; Zhang, Chengxiao; Sun, Xuping

    2016-06-01

    The development of highly efficient electrocatalysts for water splitting is critical for various renewable-energy technologies. In this letter, we demonstrate a cobalt phosphide nanowire array grown on a Ti mesh (CoP/TM) behaving as a bifunctional electrocatalyst for water splitting. The CoP/TM electrode delivers 10 mA cm‑2 at an overpotential of 72 mV for the hydrogen evolution reaction (HER) and 310 mV for the oxygen evolution reaction (OER) in 1.0 M KOH. Furthermore, its corresponding two-electrode alkaline electrolyzer displays 10 mA cm‑2 at 1.64 V.

  1. Solution-based synthesis and purification of zinc tin phosphide nanowires

    NASA Astrophysics Data System (ADS)

    Sheets, Erik J.; Balow, Robert B.; Yang, Wei-Chang; Stach, Eric A.; Agrawal, Rakesh

    2015-11-01

    The solution-based synthesis of nanoscale earth-abundant semiconductors has the potential to unlock simple, scalable, and tunable material processes which currently constrain development of novel compounds for alternative energy devices. One such promising semiconductor is zinc tin phosphide (ZnSnP2). We report the synthesis of ZnSnP2 nanowires via a solution-liquid-solid mechanism utilizing metallic zinc and tin in decomposing trioctylphosphine (TOP). Dried films of the reaction product are purified of binary phosphide phases by annealing at 345 °C. Tin is removed using a 0.1 M nitric acid treatment leaving pure ZnSnP2 nanowires. Diffuse reflectance spectroscopy indicates ZnSnP2 has a direct bandgap energy of 1.24 eV which is optimal for solar cell applications. Using a photoelectrochemical cell, we demonstrate cathodic photocurrent generation at open circuit conditions from the ZnSnP2 nanowires upon solar simulated illumination confirming p-type conductivity.The solution-based synthesis of nanoscale earth-abundant semiconductors has the potential to unlock simple, scalable, and tunable material processes which currently constrain development of novel compounds for alternative energy devices. One such promising semiconductor is zinc tin phosphide (ZnSnP2). We report the synthesis of ZnSnP2 nanowires via a solution-liquid-solid mechanism utilizing metallic zinc and tin in decomposing trioctylphosphine (TOP). Dried films of the reaction product are purified of binary phosphide phases by annealing at 345 °C. Tin is removed using a 0.1 M nitric acid treatment leaving pure ZnSnP2 nanowires. Diffuse reflectance spectroscopy indicates ZnSnP2 has a direct bandgap energy of 1.24 eV which is optimal for solar cell applications. Using a photoelectrochemical cell, we demonstrate cathodic photocurrent generation at open circuit conditions from the ZnSnP2 nanowires upon solar simulated illumination confirming p-type conductivity. Electronic supplementary information (ESI

  2. Efficient telecom to visible wavelength conversion in doubly resonant gallium phosphide microdisks

    NASA Astrophysics Data System (ADS)

    Lake, David P.; Mitchell, Matthew; Jayakumar, Harishankar; dos Santos, Laís Fujii; Curic, Davor; Barclay, Paul E.

    2016-01-01

    Resonant second harmonic generation between 1550 nm and 775 nm with normalized outside efficiency > 3.8 × 10 - 4 mW - 1 is demonstrated in a gallium phosphide microdisk supporting high-Q modes at visible ( Q ˜ 10 4 ) and infrared ( Q ˜ 10 5 ) wavelengths. The double resonance condition is satisfied for a specific pump power through intracavity photothermal temperature tuning using ˜ 360 μ W of 1550 nm light input to a fiber taper and coupled to a microdisk resonance. Power dependent efficiency consistent with a simple model for thermal tuning of the double resonance condition is observed.

  3. An efficient bifunctional electrocatalyst for water splitting based on cobalt phosphide.

    PubMed

    Yang, Libin; Qi, Honglan; Zhang, Chengxiao; Sun, Xuping

    2016-06-10

    The development of highly efficient electrocatalysts for water splitting is critical for various renewable-energy technologies. In this letter, we demonstrate a cobalt phosphide nanowire array grown on a Ti mesh (CoP/TM) behaving as a bifunctional electrocatalyst for water splitting. The CoP/TM electrode delivers 10 mA cm(-2) at an overpotential of 72 mV for the hydrogen evolution reaction (HER) and 310 mV for the oxygen evolution reaction (OER) in 1.0 M KOH. Furthermore, its corresponding two-electrode alkaline electrolyzer displays 10 mA cm(-2) at 1.64 V. PMID:27146428

  4. A Flexible Electrode Based on Iron Phosphide Nanotubes for Overall Water Splitting.

    PubMed

    Yan, Ya; Xia, Bao Yu; Ge, Xiaoming; Liu, Zhaolin; Fisher, Adrian; Wang, Xin

    2015-12-01

    The design of cheap and efficient water splitting systems for sustainable hydrogen production has attracted increasing attention. A flexible electrode, based on carbon cloth substrate and iron phosphide nanotubes coated with an iron oxide/phosphate layer, is shown to catalyze overall water splitting. The as-prepared flexible electrode demonstrates remarkable electrocatalytic activity for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) at modest overpotentials. The surface iron oxide/phosphate, which is formed in situ, is proposed to improve the HER activity by facilitating the water-dissociation step and serves directly as the catalytically-active component for the OER process. PMID:26493157

  5. Osmium isotopes in Ivory Coast tektites: Confirmation of a meteoritic component and rhenium depletion

    NASA Astrophysics Data System (ADS)

    Koeberl, Christian; Shirey, Steven B.

    1993-03-01

    The sensitive negative thermal ionization mass spectrometry method was used for the measurement of concentrations and isotopic ratios of osmium and rhenium in four Ivory Coast tektites. These tektites have crustal major and trace element composition, as well as large negative epsilonNd(-20) and positive epsilonSr(+260 to +300) which are characteristic for old continental crust. Os concentrations ranging from 0.09 to 0.30 ppb were found, clearly much higher than average crustal values, Os-187/Os-186 ratios of about 1.2-1.7, and low Re-187/Os-186 ratios. These results show unambiguously the existence of a meteoritic component (on the order of 0.06%) in the Ivory Coast tektites. Low Re abundances are the result of fractionation of Re during the impact.

  6. Q -dependent electronic excitations in osmium: Pressure- and temperature-induced effects

    NASA Astrophysics Data System (ADS)

    Ponosov, Yu. S.; Struzhkin, V. V.; Goncharov, A. F.; Streltsov, S. V.

    2008-12-01

    Raman scattering by electrons and phonons has been studied in single crystals of the 5d transition-metal osmium under pressures up to 60 GPa in the temperature range of 10-300 K. An anomalous increase in the electronic light-scattering cross section was found in the pressure range of 20-30 GPa with the use of green and blue excitation wavelengths. At these conditions, we observe an appearance of well-defined electronic peaks at ˜580cm-1 for the wave-vector direction q∥[0001] and at ˜350cm-1 for q∥[101¯0] . The comparison of q dependencies measured and calculated from the first-principles spectra suggests a strong volume- and temperature-dependent renormalization of the energies and damping of the electronic states near the Fermi level.

  7. Osmium isotopes in Ivory Coast tektites: Confirmation of a meteoritic component and rhenium depletion

    NASA Technical Reports Server (NTRS)

    Koeberl, Christian; Shirey, Steven B.

    1993-01-01

    The sensitive negative thermal ionization mass spectrometry method was used for the measurement of concentrations and isotopic ratios of osmium and rhenium in four Ivory Coast tektites. These tektites have crustal major and trace element composition, as well as large negative epsilon(sub Nd)(-20) and positive epsilon(sub Sr)(+260 to +300) which are characteristic for old continental crust. Os concentrations ranging from 0.09 to 0.30 ppb were found, clearly much higher than average crustal values, Os-187/Os-186 ratios of about 1.2-1.7, and low Re-187/Os-186 ratios. These results show unambiguously the existence of a meteoritic component (on the order of 0.06%) in the Ivory Coast tektites. Low Re abundances are the result of fractionation of Re during the impact.

  8. Striking difference in antiproliferative activity of ruthenium- and osmium-nitrosyl complexes with azole heterocycles.

    PubMed

    Büchel, Gabriel E; Gavriluta, Anatolie; Novak, Maria; Meier, Samuel M; Jakupec, Michael A; Cuzan, Olesea; Turta, Constantin; Tommasino, Jean-Bernard; Jeanneau, Erwann; Novitchi, Ghenadie; Luneau, Dominique; Arion, Vladimir B

    2013-06-01

    Ruthenium nitrosyl complexes of the general formulas (cation)(+)[cis-RuCl4(NO)(Hazole)](-), where (cation)(+) = (H2ind)(+), Hazole = 1H-indazole (Hind) (1c), (cation)(+) = (H2pz)(+), Hazole = 1H-pyrazole (Hpz) (2c), (cation)(+) = (H2bzim)(+), Hazole = 1H-benzimidazole (Hbzim) (3c), (cation)(+) = (H2im)(+), Hazole = 1H-imidazole (Him) (4c) and (cation)(+)[trans-RuCl4(NO)(Hazole)](-), where (cation)(+) = (H2ind)(+), Hazole = 1H-indazole (1t), (cation)(+) = (H2pz)(+), Hazole = 1H-pyrazole (2t), as well as osmium analogues of the general formulas (cation)(+)[cis-OsCl4(NO)(Hazole)](-), where (cation)(+) = (n-Bu4N)(+), Hazole =1H-indazole (5c), 1H-pyrazole (6c), 1H-benzimidazole (7c), 1H-imidazole (8c), (cation)(+) = Na(+); Hazole =1H-indazole (9c), 1H-benzimidazole (10c), (cation)(+) = (H2ind)(+), Hazole = 1H-indazole (11c), (cation)(+) = H2pz(+), Hazole = 1H-pyrazole (12c), (cation)(+) = (H2im)(+), Hazole = 1H-imidazole (13c), and (cation)(+)[trans-OsCl4(NO)(Hazole)](-), where (cation)(+) = n-Bu4N(+), Hazole = 1H-indazole (5t), 1H-pyrazole (6t), (cation)(+) = Na(+), Hazole = 1H-indazole (9t), (cation)(+) = (H2ind)(+), Hazole = 1H-indazole (11t), (cation)(+) = (H2pz)(+), Hazole = 1H-pyrazole (12t), have been synthesized. The compounds have been comprehensively characterized by elemental analysis, ESI mass spectrometry, spectroscopic techniques (IR, UV-vis, 1D and 2D NMR) and X-ray crystallography (1c·CHCl3, 1t·CHCl3, 2t, 3c, 6c, 6t, 8c). The antiproliferative activity of water-soluble compounds (1c, 1t, 3c, 4c and 9c, 9t, 10c, 11c, 11t, 12c, 12t, 13c) in the human cancer cell lines A549 (nonsmall cell lung carcinoma), CH1 (ovarian carcinoma), and SW480 (colon adenocarcinoma) has been assayed. The effects of metal (Ru vs Os), cis/trans isomerism, and azole heterocycle identity on cytotoxic potency and cell line selectivity have been elucidated. Ruthenium complexes (1c, 1t, 3c, and 4c) yielded IC50 values in the low micromolar concentration range. In contrast to most

  9. Striking Difference in Antiproliferative Activity of Ruthenium- and Osmium-Nitrosyl Complexes with Azole Heterocycles

    PubMed Central

    2013-01-01

    Ruthenium nitrosyl complexes of the general formulas (cation)+[cis-RuCl4(NO)(Hazole)]−, where (cation)+ = (H2ind)+, Hazole = 1H-indazole (Hind) (1c), (cation)+ = (H2pz)+, Hazole = 1H-pyrazole (Hpz) (2c), (cation)+ = (H2bzim)+, Hazole = 1H-benzimidazole (Hbzim) (3c), (cation)+ = (H2im)+, Hazole = 1H-imidazole (Him) (4c) and (cation)+[trans-RuCl4(NO)(Hazole)]−, where (cation)+ = (H2ind)+, Hazole = 1H-indazole (1t), (cation)+ = (H2pz)+, Hazole = 1H-pyrazole (2t), as well as osmium analogues of the general formulas (cation)+[cis-OsCl4(NO)(Hazole)]−, where (cation)+ = (n-Bu4N)+, Hazole =1H-indazole (5c), 1H-pyrazole (6c), 1H-benzimidazole (7c), 1H-imidazole (8c), (cation)+ = Na+; Hazole =1H-indazole (9c), 1H-benzimidazole (10c), (cation)+ = (H2ind)+, Hazole = 1H-indazole (11c), (cation)+ = H2pz+, Hazole = 1H-pyrazole (12c), (cation)+ = (H2im)+, Hazole = 1H-imidazole (13c), and (cation)+[trans-OsCl4(NO)(Hazole)]−, where (cation)+ = n-Bu4N+, Hazole = 1H-indazole (5t), 1H-pyrazole (6t), (cation)+ = Na+, Hazole = 1H-indazole (9t), (cation)+ = (H2ind)+, Hazole = 1H-indazole (11t), (cation)+ = (H2pz)+, Hazole = 1H-pyrazole (12t), have been synthesized. The compounds have been comprehensively characterized by elemental analysis, ESI mass spectrometry, spectroscopic techniques (IR, UV–vis, 1D and 2D NMR) and X-ray crystallography (1c·CHCl3, 1t·CHCl3, 2t, 3c, 6c, 6t, 8c). The antiproliferative activity of water-soluble compounds (1c, 1t, 3c, 4c and 9c, 9t, 10c, 11c, 11t, 12c, 12t, 13c) in the human cancer cell lines A549 (nonsmall cell lung carcinoma), CH1 (ovarian carcinoma), and SW480 (colon adenocarcinoma) has been assayed. The effects of metal (Ru vs Os), cis/trans isomerism, and azole heterocycle identity on cytotoxic potency and cell line selectivity have been elucidated. Ruthenium complexes (1c, 1t, 3c, and 4c) yielded IC50 values in the low micromolar concentration range. In contrast to most pairs of analogous ruthenium and osmium complexes known, they turned

  10. Osmium, ruthenium, iridium and uranium in silicates and chromite from the eastern Bushveld Complex, South Africa

    USGS Publications Warehouse

    Gijbels, R.h.; Millard, H.T., Jr.; Desborough, G.A.; Bartel, A.J.

    1974-01-01

    Osmium, ruthenium, iridium and uranium contents were determined in eight ortho pyroxene, seven plagioclase, and three chromite mineral separates from the eastern Bushveld Complex. Neutron activation analysis was used to measure the platinum metals, and uranium was determined by a fission track technique. The platinum metals were found to be present within each mine??ral in the proportions Os:Ru:Ir = 1:7:1, while the concentrations of these metals in the minerals are in the ratios orthopyroxene:plagioclase:chromite = 1:16:700. The concentration of uranium was found to range from 11 to 66 ppb (parts per billion) and not to vary significantly from mineral to mineral. The data for the platinum metals are consistent with a model in which the eastern Bushveld Complex was formed by the fractional crystallization of two separately injected magmas. A computer fit of this model to these data indicates that the initial concentrations of Os, Ru and Ir in the first magma were 0.24, 2.0 and 0.21 ppb and in the second magma were 0.16, 1.1 and 0.18 ppb, respectively. The fit also yields the distribution coefficients for the partitioning between the liquid and cumulus orthopyroxene, cumulus plagioclase and cumulus chromite. These coefficients (mineral/liquid) for osmium are 4.5, 66 and 2700; for ruthenium, they are 5, 65 and 2700; and for iridium, they are 4, 60 and 1600. To make this fit, it was necessary to hypothesize the existence of two types of chromite: one type with a large distribution coefficient, presumably formed as a cumulus phase at high temperature, and another, more prevalent type with a smaller distribution coefficient, which may have been formed by postcumulus growth at a lower temperature. This hypothesis is supported by data for coexisting chromite-silicate pairs, which indicate that the chromite grains expelled these platinum metals as they cooled. ?? 1974.

  11. Potent organo-osmium compound shifts metabolism in epithelial ovarian cancer cells

    PubMed Central

    Hearn, Jessica M.; Romero-Canelón, Isolda; Munro, Alison F.; Fu, Ying; Pizarro, Ana M.; Garnett, Mathew J.; McDermott, Ultan; Carragher, Neil O.; Sadler, Peter J.

    2015-01-01

    The organometallic “half-sandwich” compound [Os(η6-p-cymene)(4-(2-pyridylazo)-N,N-dimethylaniline)I]PF6 is 49× more potent than the clinical drug cisplatin in the 809 cancer cell lines that we screened and is a candidate drug for cancer therapy. We investigate the mechanism of action of compound 1 in A2780 epithelial ovarian cancer cells. Whole-transcriptome sequencing identified three missense mutations in the mitochondrial genome of this cell line, coding for ND5, a subunit of complex I (NADH dehydrogenase) in the electron transport chain. ND5 is a proton pump, helping to maintain the coupling gradient in mitochondria. The identified mutations correspond to known protein variants (p.I257V, p.N447S, and p.L517P), not reported previously in epithelial ovarian cancer. Time-series RNA sequencing suggested that osmium-exposed A2780 cells undergo a metabolic shunt from glycolysis to oxidative phosphorylation, where defective machinery, associated with mutations in complex I, could enhance activity. Downstream events, measured by time-series reverse-phase protein microarrays, high-content imaging, and flow cytometry, showed a dramatic increase in mitochondrially produced reactive oxygen species (ROS) and subsequent DNA damage with up-regulation of ATM, p53, and p21 proteins. In contrast to platinum drugs, exposure to this organo-osmium compound does not cause significant apoptosis within a 72-h period, highlighting a different mechanism of action. Superoxide production in ovarian, lung, colon, breast, and prostate cancer cells exposed to three other structurally related organo-Os(II) compounds correlated with their antiproliferative activity. DNA damage caused indirectly, through selective ROS generation, may provide a more targeted approach to cancer therapy and a concept for next-generation metal-based anticancer drugs that combat platinum resistance. PMID:26162681

  12. THE FINE STRUCTURE OF CHLOROPLAST STROMA FOLLOWING ALDEHYDE OSMIUM-TETROXIDE FIXATION.

    PubMed

    GUNNING, B E

    1965-01-01

    Markedly improved fixation of leaf tissues is obtained by means of a glutaraldehyde (or acrolein)-osmium tetroxide procedure, as compared with the results of potassium permanganate or osmium tetroxide fixation methods. The procedure has proved useful in all species so far examined. Chloroplasts are particularly well preserved. In this paper details of components of the ground-substance of Avena sativa plastids are presented. They include the following:-(i) The "tromacentre" is an area of aggregated fibrils, each 85 A in diameter, and of uncertain length. Individual fibrils may be composed of subunits. The whole aggregate is usually up to 1 micro in diameter, and is visible in thin sections in the light microcope. It is present at all stages of plastid development, and, under conditions of rapid synthesis in the plastid, it may be up to 2 micro in diameter. Evidence that it is proteinaceous is presented. Osmiophilic globules are often associated with it. (ii) Areas which resemble bacterial and blue-green algal nucleoplasms, containing fibrils approximately 30 A wide. These regions are smaller than the stromacentre and, like that structure, they occur in all stages of plastid development. Unlike it, there are several such areas per chloroplast. (iii) Particles which have some of the morphological and staining characteristics of ribosomes. Present at all stages of development, they are approximately two-thirds the size of the cytoplasmic ribosomes. They can occur in groups, thus resembling polyribosomes. (iv) The remaining material is granular, and may include dissociated portions of stromacentre material. The validity of the observations and their significance is discussed. PMID:14286298

  13. Potent organo-osmium compound shifts metabolism in epithelial ovarian cancer cells.

    PubMed

    Hearn, Jessica M; Romero-Canelón, Isolda; Munro, Alison F; Fu, Ying; Pizarro, Ana M; Garnett, Mathew J; McDermott, Ultan; Carragher, Neil O; Sadler, Peter J

    2015-07-21

    The organometallic "half-sandwich" compound [Os(η(6)-p-cymene)(4-(2-pyridylazo)-N,N-dimethylaniline)I]PF6 is 49× more potent than the clinical drug cisplatin in the 809 cancer cell lines that we screened and is a candidate drug for cancer therapy. We investigate the mechanism of action of compound 1 in A2780 epithelial ovarian cancer cells. Whole-transcriptome sequencing identified three missense mutations in the mitochondrial genome of this cell line, coding for ND5, a subunit of complex I (NADH dehydrogenase) in the electron transport chain. ND5 is a proton pump, helping to maintain the coupling gradient in mitochondria. The identified mutations correspond to known protein variants (p.I257V, p.N447S, and p.L517P), not reported previously in epithelial ovarian cancer. Time-series RNA sequencing suggested that osmium-exposed A2780 cells undergo a metabolic shunt from glycolysis to oxidative phosphorylation, where defective machinery, associated with mutations in complex I, could enhance activity. Downstream events, measured by time-series reverse-phase protein microarrays, high-content imaging, and flow cytometry, showed a dramatic increase in mitochondrially produced reactive oxygen species (ROS) and subsequent DNA damage with up-regulation of ATM, p53, and p21 proteins. In contrast to platinum drugs, exposure to this organo-osmium compound does not cause significant apoptosis within a 72-h period, highlighting a different mechanism of action. Superoxide production in ovarian, lung, colon, breast, and prostate cancer cells exposed to three other structurally related organo-Os(II) compounds correlated with their antiproliferative activity. DNA damage caused indirectly, through selective ROS generation, may provide a more targeted approach to cancer therapy and a concept for next-generation metal-based anticancer drugs that combat platinum resistance. PMID:26162681

  14. Silicon nanowire arrays coupled with cobalt phosphide spheres as low-cost photocathodes for efficient solar hydrogen evolution.

    PubMed

    Bao, Xiao-Qing; Fatima Cerqueira, M; Alpuim, Pedro; Liu, Lifeng

    2015-07-01

    We demonstrate the first example of silicon nanowire array photocathodes coupled with hollow spheres of the emerging earth-abundant cobalt phosphide catalysts. Compared to bare silicon nanowire arrays, the hybrid electrodes exhibit significantly improved photoelectrochemical performance toward the solar-driven H2 evolution reaction. PMID:26050844

  15. Three-dimensional interconnected nickel phosphide networks with hollow microstructures and desulfurization performance

    SciTech Connect

    Zhang, Shuna; Zhang, Shujuan; Song, Limin; Wu, Xiaoqing; Fang, Sheng

    2014-05-01

    Graphical abstract: Three-dimensional interconnected nickel phosphide networks with hollow microstructures and desulfurization performance. - Highlights: • Three-dimensional Ni{sub 2}P has been prepared using foam nickel as a template. • The microstructures interconnected and formed sponge-like porous networks. • Three-dimensional Ni{sub 2}P shows superior hydrodesulfurization activity. - Abstract: Three-dimensional microstructured nickel phosphide (Ni{sub 2}P) was fabricated by the reaction between foam nickel (Ni) and phosphorus red. The as-prepared Ni{sub 2}P samples, as interconnected networks, maintained the original mesh structure of foamed nickel. The crystal structure and morphology of the as-synthesized Ni{sub 2}P were characterized by X-ray diffraction, scanning electron microscopy, automatic mercury porosimetry and X-ray photoelectron spectroscopy. The SEM study showed adjacent hollow branches were mutually interconnected to form sponge-like networks. The investigation on pore structure provided detailed information for the hollow microstructures. The growth mechanism for the three-dimensionally structured Ni{sub 2}P was postulated and discussed in detail. To investigate its catalytic properties, SiO{sub 2} supported three-dimensional Ni{sub 2}P was prepared successfully and evaluated for the hydrodesulfurization (HDS) of dibenzothiophene (DBT). DBT molecules were mostly hydrogenated and then desulfurized by Ni{sub 2}P/SiO{sub 2}.

  16. ANALYSIS OF THE WATER-SPLITTING CAPABILITIES OF GALLIUM INDIUM PHOSPHIDE NITRIDE (GaInPN)

    SciTech Connect

    Head, J.; Turner, J.

    2007-01-01

    With increasing demand for oil, the fossil fuels used to power society’s vehicles and homes are becoming harder to obtain, creating pollution problems and posing hazard’s to people’s health. Hydrogen, a clean and effi cient energy carrier, is one alternative to fossil fuels. Certain semiconductors are able to harness the energy of solar photons and direct it into water electrolysis in a process known as photoelectrochemical water-splitting. P-type gallium indium phosphide (p-GaInP2) in tandem with GaAs is a semiconductor system that exhibits water-splitting capabilities with a solar-tohydrogen effi ciency of 12.4%. Although this material is effi cient at producing hydrogen through photoelectrolysis it has been shown to be unstable in solution. By introducing nitrogen into this material, there is great potential for enhanced stability. In this study, gallium indium phosphide nitride Ga1-yInyP1-xNx samples were grown using metal-organic chemical vapor deposition in an atmospheric-pressure vertical reactor. Photocurrent spectroscopy determined these materials to have a direct band gap around 2.0eV. Mott-Schottky analysis indicated p-type behavior with variation in fl atband potentials with varied frequencies and pH’s of solutions. Photocurrent onset and illuminated open circuit potential measurements correlated to fl atband potentials determined from previous studies. Durability analysis suggested improved stability over the GaInP2 system.

  17. Could hydroxyethyl starch be a therapeutic option in management of acute aluminum phosphide toxicity?

    PubMed

    Marashi, Sayed Mahdi; Arefi, Mohammad; Behnoush, Behnam; Nasrabad, Mahdi Ghazanfari; Nasrabadi, Zeynab Nasri

    2011-04-01

    Acute aluminum phosphide poisoning is a serious toxicity and results in high mortality rate despite the progress of critical care. After ingestion, phosphine gas is released and absorbed quickly, causing systemic poisoning and cell hypoxia. Excessive thirst, severe hypotension, arrhythmias, tachypnea, and severe metabolic acidosis are the common clinical manifestations. We think acute metabolic response which characteristically occurs in severe injury also happens in aluminum phosphide poisoning. Necropsy examinations indicate congestion in almost all vital organs because of leakage of fluids from intravascular to extravascular space. The most favorable type of fluid for intravascular volume resuscitation persists and is disputed. Colloids remain in the intravascular space rather than crystalloids, and provide more rapid hemodynamic stabilization. Furthermore, hydroxyethyl starch solution may have other benefits e.g. it can reduce the extra vascular leak of albumin and fluids from an endothelial injury site. As refractory hypotension and cardiovascular collapse, because leakage of fluids from intravascular to extravascular space are common cause of death in this toxicity, we propose that hydroxyethyl starch can dominate this refractory hypotension and consequently acute metabolic response. PMID:21288649

  18. Atomically Resolved Site-Isolated Catalyst on MgO: Mononuclear Osmium Dicarbonyls formed from Os3(CO)12

    SciTech Connect

    Aydin, Ceren; kulkarni, Apoorva; Chi, Miaofang; Browning, Nigel D.; Gates, Bruce C.

    2012-01-01

    Supported triosmium clusters, formed from Os{sub 3}(CO){sub 12} on MgO, were treated in helium at 548 K for 2 h, causing fragmentation of the cluster frame and the formation of mononuclear osmium dicarbonyls. The cluster breakup and the resultant fragmented species were characterized by infrared and X-ray absorption spectroscopies, and the fragmented species were imaged by scanning transmission electron microscopy. The spectra identify the surface osmium complexes as Os(CO){sub 2}{l_brace}O{sub support}{r_brace}{sub n} (n = 3 or 4) (where the braces denote support surface atoms). The images show site-isolated Os atoms in mononuclear osmium species on MgO. The intensity analysis on the images of the MgO(110) face showed that the Os atoms were located atop Mg columns. This information led to a model of the Os(CO){sub 2} on MgO(110), with the distances approximated as those determined by EXAFS spectroscopy, which are an average over the whole MgO surface; the results imply that these complexes were located at Mg vacancies.

  19. Wiring microbial biofilms to the electrode by osmium redox polymer for the performance enhancement of microbial fuel cells.

    PubMed

    Yuan, Yong; Shin, Hyosul; Kang, Chan; Kim, Sunghyun

    2016-04-01

    An osmium redox polymer, PAA-PVI-[Os(4,4'-dimethyl-2,2'-bipyridine)2Cl]+/2+ that has been used in enzymatic fuel cells and microbial sensors, was applied for the first time to the anode of single-chamber microbial fuel cells with the mixed culture inoculum aiming at enhancing performance. Functioning as a molecular wire connecting the biofilm to the anode, power density increased from 1479 mW m(-2) without modification to 2355 mW m(-2) after modification of the anode. Evidence from cyclic voltammetry showed that the catalytic activity of an anodic biofilm was greatly enhanced in the presence of an osmium redox polymer, indicating that electrons were more efficiently transferred to the anode via co-immobilized osmium complex tethered to wiring polymer chains at the potential range of -0.3 V-+0.1 V (vs. SCE). The optimum amount of the redox polymer was determined to be 0.163 mg cm(-2). PMID:26599210

  20. Characterization of a glucose sensor prepared by electropolymerization of pyrroles containing a tris-bipyridine osmium complex.

    PubMed

    Tsujimoto, Masaki; Yabutani, Tomoki; Sano, Atsushi; Tani, Yuji; Murotani, Hiroki; Mishima, Yuji; Maruyama, Kenichi; Yasuzawa, Mikito; Motonaka, Junko

    2007-01-01

    A glucose sensor was developed by electrocopolymerization using pyrroles containing a tris-bipyridine (bpy) osmium complex (Os-py), pyrrole (py), pyrrole propanoic acid (PPA) and glucose oxidase (GOx) to improve the key performance characteristics, such as the sensitivity, selectivity, and long-term stability. Tris-bipyridine osmium pyrrole complexes with four different methylene moieties were utilized to correlate the methylene length with the glucose sensor performance. The electrocatalytic response of glucose was clearly observed at electrodes modified with Os-py, except for the electrode immobilized with the Os-py complex containing the shortest methylene moiety. The current response to glucose increased up to a concentration of 100 mmol dm(-3). The electrocatalytic response to glucose at the [Os(bpy)(2)(py(6)-bpy)](2+/3+)/py/PPA/GOx electrode was stable for more than 100 days. Dissolved oxygen and potential interference compounds (ascorbic acid, uric acid, and acetaminophen) minimally perturbed the current response to glucose at the [Os(DM-bpy)(2)(py(6)-bpy)](2+/3+)/py/PPA/GOx electrode. Based on these results, a longer methylene moiety appears to improve the performance characteristics of a glucose sensor fabricated via the electropolymerization of tris-bipyridine osmium pyrrole complexes. PMID:17213625

  1. The cyro-thermochromatographic separator (CTS): A new detectionand separation system for highly volatile osmium and hassium (element108) tetroxides

    SciTech Connect

    Kirbach, U.W.; Folden III, C.M.; Ginter, T.N.; Gregorich, K.E.; Lee, D.M.; Ninov, V.; Omtvedt, J.P.; Patin, J.B.; Seward, N.K.; Strellis,D.A.; Sudowe, R.; Wilk, P.A.; Zielinski, P.M.; Hoffman, D.C.; Nitsche, H.

    2002-03-08

    We implemented a new concept for heavy element chemistry research using an ion separator to separate the desired products from the beam, transfer products and other undesirable by-products prior to chemical studies. First, a Recoil product Transfer Chamber (RTC) was designed and attached to the Berkeley Gas-filled Separator (BGS) to collect and transfer the recoiling products to the chemical separation system. The RTC consists of a wire-grid-supported thin mylar foil ({le}) 200 {micro}g/cm{sup 2} that separates the BGS detector chamber, at 1.3 mbar pressure, from the chemistry system at different pressures ranging from 480 mbar to 2000 mbar. The overall transport efficiency ranged between 30% and 15%, compared to the activity measured in the focal plane detector of the BGS. The CTS was designed as a separation and {alpha}-decay detection system for the highly volatile tetroxides of osmium and hassium, element 108. The CTS, shown in figure 1, consists of two rows of 32-{alpha} detectors arranged along a negative temperature gradient. The tetroxides adsorb on the surface of one of the silicone photodiodes at a certain deposition temperature, and the nuclide is then identified by the {alpha}-decay. To test the CTS with the expected hassium homologue osmium, different {alpha}-active osmium isotopes were produced using the nuclear reactions {sup 118}Sn({sup 56}Fe, 4,5n) {sup 170,169}Os and {sup 120}Sn({sup 56}Fe, 4,5n) {sup 172,171}Os. After preseparation in the BGS, a mixture of 90% helium and 10% oxygen was used to transport the osmium to a quartz tube heated to 1225 K, where OsO{sub 4} was formed. The negative temperature gradient in the CTS ranged from 248 K to 173 K. Using a flow rate of 500 mL/min, most of the osmium activity was adsorbed at a temperature of about 203 K. From the measured {alpha}-activity distribution, an adsorption enthalpy of 40 {+-} 1 kJ/mol for OsO{sub 4} on the detector surface was calculated using Monte Carlo simulations. The results show

  2. Amide-Directed Formation of Five-Coordinate Osmium Alkylidenes from Alkynes

    PubMed Central

    2015-01-01

    The amide-directed synthesis of five-coordinate osmium alkylidene derivatives from alkynes is reported. These types of complexes, which have been elusive until now because of the tendency of osmium to give hydride alkylidyne species, are prepared by reaction of the dihydride OsH2Cl2(PiPr3)2 (1) with terminal alkynes containing a distal amide group. Complex 1 reacts with N-phenylhex-5-ynamide and N-phenylhepta-6-ynamide to give OsCl2{=C(CH3)(CH2)nNH(CO)Ph}(PiPr3)2 (n = 3 (2), 4 (3)). The relative position of carbonyl and NH groups in the organic substrates has no influence on the reaction. Thus, treatment of 1 with N-(pent-4-yn-1-yl)benzamide leads to OsCl2{=C(CH3)(CH2)3NHC(O)Ph}(PiPr3)2 (4). The new compounds are intermediate species in the cleavage of the C–C triple bond of the alkynes. Under mild conditions, they undergo the rupture of the Cα–CH3 bond of the alkylidene, which comes from the alkyne triple bond, to afford six-coordinate hydride–alkylidyne derivatives. In dichloromethane, complex 2 gives a 10:7 mixture of OsHCl2{≡C(CH2)3C(O)NHPh}(PiPr3)2 (5) and OsHCl2{≡CCH(CH3)(CH2)2C(O)NHPh}(PiPr3)2 (6). The first complex contains a linear separation between the alkylidyne Cα atom and the amide group, whereas the spacer is branched in the second complex. In contrast to the case for 2, complex 4 selectively affords OsHCl2{≡C(CH2)3NHC(O)Ph}(PiPr3)2 (7). In spite of their instability, these compounds give the alkylidene–allene metathesis, being a useful entry to five-coordinate vinylidene complexes, including the dicarbon-disubstituted OsCl2(=C=CMe2)(PiPr3)2 (8) and the monosubstituted OsCl2(=C=CHCy)(PiPr3)2 (9). PMID:26877575

  3. Origin of platinum-group mineral assemblages in a mantle tectonite at Unst deduced from mineral chemistry and osmium isotopes

    NASA Astrophysics Data System (ADS)

    Badanina, Inna Yu.; Lord, Richard A.; Malitch, Kreshimir N.; Meisel, Thomas C.

    2013-04-01

    This study assesses textural and mineral chemistry data, whole-rock and mineral separate Os-isotope compositions for distinct platinum-group mineral (PGM) inclusion assemblages in an isolated chromitite pod at Harold's Grave, which occurrs in a mantle tectonite at Unst in the Shetland Ophiolite Complex, Scotland. The investigation employed a multi-technique approach and utilized a number of analytical techniques, including electron microprobe analysis, ID ICP-MS after high pressure acid digestion, and LA MC-ICP-MS. Two distinct PGM assemblages have been recognized. They comprise a 'primary' euhedrally shaped (up to 15 μm in size) PGM assemblage, which occur as inclusions in chromite, and a modified 'secondary' subeuhedral to anhedral PGM assemblage (up to 100 μm) associated with Ru-rich pentlandite observed in cracks filled by chlorite or serpentine, interstitially to chromite grains. A 'primary' PGM assemblage is represented by solitary grains of laurite or iridian osmium and composite grains that display well defined phase boundaries between two or three distinct PGM. The latter are dominated by laurite and iridian osmium, with subordinate laurite + osmian iridium + iridian osmium and rare laurite + Ir-Rh alloy + Rh-rich sulphide (possibly prassoite). The compositional variability of associated laurite and Os-rich alloys at Harold's Grave fit the predicted compositions of experiment W-1200-0.37 of Andrews and Brenan (2002) providing unequivocal information on conditions of their genesis, with the upper thermal stability of laurite in equilibrium with Os-rich alloys estimated at 1200 - 1250° C and f(S2) of 10-0.39-10-0.07. The inconsistent grouping of different primary PGM grains argues against an origin by subsolidus exsolution from the chromite host, providing useful information on conditions of their genesis. The 'secondary' PGM assemblage is polyphase, with dominant laurite, intimately intergrown with native osmium, irarsite and Ru-rich pentlandite. This

  4. Development of a reliable analytical method for the precise extractive spectrophotometric determination of osmium(VIII) with 2-nitrobenzaldehydethiocarbohydrazone: Analysis of alloys and real sample.

    PubMed

    Zanje, Sunil B; Kokare, Arjun N; Suryavanshi, Vishal J; Waghmode, Duryodhan P; Joshi, Sunil S; Anuse, Mansing A

    2016-12-01

    The proposed method demonstrates that the osmium(VIII) forms complex with 2-NBATCH from 0.8molL(-1) HCl at room temperature. The complex formed was extracted in 10mL of chloroform with a 5min equilibration time. The absorbance of the red colored complex was measured at 440nm against the reagent blank. The Beer's law was obeyed in the range of 5-25μgmL(-1), the optimum concentration range was 10-20μgmL(-1) of osmium(VIII) as evaluated by Ringbom's plot. Molar absorptivity and Sandell's sensitivity of osmium(VIII)-2NBATCH complex in chloroform is 8.94×10(3)Lmol(-1)cm(-1) and 0.021μgcm(-2), respectively. The composition of osmium(VIII)-2NBATCH complex was 1:2 investigated from Job's method of continuous variation, Mole ratio method and slope ratio method. The interference of diverse ions was studied and masking agents were used wherever necessary. The present method was successfully applied for determination of osmium(VIII) from binary, ternary and synthetic mixtures corresponding to alloys and real samples. The validity of the method was confirmed by finding the relative standard deviation for five determinations which was 0.29%. PMID:27380306

  5. Backscattered electron image of osmium-impregnated/macerated tissues as a novel technique for identifying the cis-face of the Golgi apparatus by high-resolution scanning electron microscopy.

    PubMed

    Koga, D; Bochimoto, H; Watanabe, T; Ushiki, T

    2016-07-01

    The osmium maceration method with scanning electron microscopy (SEM) enabled to demonstrate directly the three-dimensional (3D) structure of membranous cell organelles. However, the polarity of the Golgi apparatus (that is, the cis-trans axis) can hardly be determined by SEM alone, because there is no appropriate immunocytochemical method for specific labelling of its cis- or trans-faces. In the present study, we used the osmium impregnation method, which forms deposits of reduced osmium exclusively in the cis-Golgi elements, for preparation of specimens for SEM. The newly developed procedure combining osmium impregnation with subsequent osmium maceration specifically visualised the cis-elements of the Golgi apparatus, with osmium deposits that were clearly detected by backscattered electron-mode SEM. Prolonged osmication by osmium impregnation (2% OsO4 solution at 40°C for 40 h) and osmium maceration (0.1% OsO4 solution at 20°C for 24 h) did not significantly impair the 3D ultrastructure of the membranous cell organelles, including the Golgi apparatus. This novel preparation method enabled us to determine the polarity of the Golgi apparatus with enough information about the surrounding 3D ultrastructure by SEM, and will contribute to our understanding of the global organisation of the entire Golgi apparatus in various differentiated cells. PMID:26807791

  6. Transition Metal Phosphide Nanoparticles Supported on SBA-15 as Highly Selective Hydrodeoxygenation Catalysts for the Production of Advanced Biofuels.

    PubMed

    Yang, Yongxing; Ochoa-Hernández, Cristina; de la Peña O'Shea, Víctor A; Pizarro, Patricia; Coronado, Juan M; Serrano, David P

    2015-09-01

    A series of catalysts constituted by nanoparticles of transition metal (M = Fe, Co, Ni and Mo) phosphides (TMP) dispersed on SBA-15 were synthesized by reduction of the corresponding metal phosphate precursors previously impregnated on the mesostructured support. All the samples contained a metal-loading of 20 wt% and with an initial M/P mole ratio of 1, and they were characterized by X-ray diffraction (XRD), N2 sorption, H2-TPR and transmission electron microscopy (TEM). Metal phosphide nanocatalysts were tested in a high pressure continuous flow reactor for the hydrodeoxygenation (HDO) of a methyl ester blend containing methyl oleate (C17H33-COO-CH3) as main component (70%). This mixture constitutes a convenient surrogate of triglycerides present in vegetable oils, and following catalytic hydrotreating yields mainly n-alkanes. The results of the catalytic assays indicate that Ni2P/SBA-15 catalyst presents the highest ester conversion, whereas the transformation rate is about 20% lower for MoP/SBA-15. In contrast, catalysts based on Fe and Co phosphides show a rather limited activity. Hydrocarbon distribution in the liquid product suggests that both hydrodeoxygenation and decarboxylation/decarbonylation reactions occur simultaneously over the different catalysts, although MoP/SBA-15 possess a selectivity towards hydrodeoxygenation exceeding 90%. Accordingly, the catalyst based on MoP affords the highest yield of n-octadecane, which is the preferred product in terms of carbon atom economy. Subsequently, in order to conjugate the advantages of both Ni and Mo phosphides, a series of catalysts containing variable proportions of both metals were prepared. The obtained results reveal that the mixed phosphides catalysts present a catalytic behavior intermediate between those of the monometallic phosphides. Accordingly, only marginal enhancement of the yield of n-octadecane is obtained for the catalysts with a Mo/Ni ratio of 3. Nevertheless, owing to this high selectivity

  7. Synthesis and Superconducting Properties of a Hexagonal Phosphide ScRhP

    NASA Astrophysics Data System (ADS)

    Inohara, Takumi; Okamoto, Yoshihiko; Yamakawa, Youichi; Takenaka, Koshi

    2016-09-01

    We report the synthesis and superconducting properties of the ternary phosphide ScRhP. The crystal structure of ScRhP is determined to be the ordered Fe2P type with the hexagonal Pbar{6}2m space group by powder X-ray diffraction experiments. Resistivity, magnetization, and heat capacity data indicate that ScRhP is a bulk superconductor with a transition temperature Tc of 2 K. This Tc is lower than that of its 5d analogue, ScIrP (Tc = 3.4 K), although ScRhP is found to have larger electronic density of states at the Fermi energy and a higher Debye temperature than those of ScIrP.

  8. Bragg coherent x-ray diffractive imaging of a single indium phosphide nanowire

    NASA Astrophysics Data System (ADS)

    Dzhigaev, D.; Shabalin, A.; Stankevič, T.; Lorenz, U.; Kurta, R. P.; Seiboth, F.; Wallentin, J.; Singer, A.; Lazarev, S.; Yefanov, O. M.; Borgström, M.; Strikhanov, M. N.; Samuelson, L.; Falkenberg, G.; Schroer, C. G.; Mikkelsen, A.; Feidenhans‘l, R.; Vartanyants, I. A.

    2016-06-01

    Three-dimensional (3D) Bragg coherent x-ray diffractive imaging (CXDI) with a nanofocused beam was applied to quantitatively map the internal strain field of a single indium phosphide nanowire. The quantitative values of the strain were obtained by pre-characterization of the beam profile with transmission ptychography on a test sample. Our measurements revealed the 3D strain distribution in a region of 150 nm below the catalyst Au particle. We observed a slight gradient of the strain in the range of ±0.6% along the [111] growth direction of the nanowire. We also determined the spatial resolution in our measurements to be about 10 nm in the direction perpendicular to the facets of the nanowire. The CXDI measurements were compared with the finite element method simulations and show a good agreement with our experimental results. The proposed approach can become an effective tool for in operando studies of the nanowires.

  9. Ab-initio calculations of electronic, transport, and structural properties of boron phosphide

    SciTech Connect

    Ejembi, J. I.; Nwigboji, I. H.; Franklin, L.; Malozovsky, Y.; Zhao, G. L.; Bagayoko, D.

    2014-09-14

    We present results from ab-initio, self-consistent density functional theory calculations of electronic and related properties of zinc blende boron phosphide (zb-BP). We employed a local density approximation potential and implemented the linear combination of atomic orbitals formalism. This technique follows the Bagayoko, Zhao, and Williams method, as enhanced by the work of Ekuma and Franklin. The results include electronic energy bands, densities of states, and effective masses. The calculated band gap of 2.02 eV, for the room temperature lattice constant of a=4.5383 Å, is in excellent agreement with the experimental value of 2.02±0.05 eV. Our result for the bulk modulus, 155.7 GPa, agrees with experiment (152–155 GPa). Our predictions for the equilibrium lattice constant and the corresponding band gap, for very low temperatures, are 4.5269 Å and 2.01 eV, respectively.

  10. Molybdenum Disulfide as a Protection Layer and Catalyst for Gallium Indium Phosphide Solar Water Splitting Photocathodes.

    PubMed

    Britto, Reuben J; Benck, Jesse D; Young, James L; Hahn, Christopher; Deutsch, Todd G; Jaramillo, Thomas F

    2016-06-01

    Gallium indium phosphide (GaInP2) is a semiconductor with promising optical and electronic properties for solar water splitting, but its surface stability is problematic as it undergoes significant chemical and electrochemical corrosion in aqueous electrolytes. Molybdenum disulfide (MoS2) nanomaterials are promising to both protect GaInP2 and to improve catalysis because MoS2 is resistant to corrosion and also possesses high activity for the hydrogen evolution reaction (HER). In this work, we demonstrate that GaInP2 photocathodes coated with thin MoS2 surface protecting layers exhibit excellent activity and stability for solar hydrogen production, with no loss in performance (photocurrent onset potential, fill factor, and light-limited current density) after 60 h of operation. This represents a 500-fold increase in stability compared to bare p-GaInP2 samples tested in identical conditions. PMID:27196435

  11. Indium phosphide solar cells: status and prospects for use in space

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Brinker, D. J.

    1986-01-01

    The current status of indium phosphide cell research is reviewed and state of the art efficiencies compared to those of GaAs and Si. It is shown that the radiation resistance of InP cells is superior to that of either GaAs or Si under 1 MeV electron and 10 MeV proton irradiation. Using lightweight blanket technology, a SEP array structure and projected cell efficiencies, array specific powers are obtained for all three cell types. Array performance is calculated as a function of time in orbit. The results indicate that arrays using InP cells can outperform those using GaAs or Si in orbits where radiation is a significant cell degradation factor. It is concluded that InP solar cells are excellent prospects for future use in the space radiation environment.

  12. Sc-Sc bonding in the new ternary phosphide ScNiP

    SciTech Connect

    Kleinke, H.; Franzen, H.F.

    1998-05-01

    The new phosphide ScNiP can be synthesized by arc-melting of ScP and Ni, or by arc-melting of Sc with NiP. The lattice constants, as obtained from the bulk sample, are a = 6.3343(8) {angstrom}, b = 3.7375(7) {angstrom}, c = 7.0917(8), and V = 167.89(4) {angstrom}{sup 3}. ScNiP crystallizes in the Co{sub 2}Si structure type. Although one might assign the trivalent state to Sc, corresponding to a formal ionic formula of Sc{sup 3+}Ni{sup {+-}0}P{sup 3{minus}}, the structure of ScNiP contains Sc-Sc bonds and shows weak metallic properties, as expected based on extended Hueckel calculations.

  13. Synthesis of the titanium phosphide telluride Ti 2PTe 2: A thermochemical approach

    NASA Astrophysics Data System (ADS)

    Philipp, Frauke; Schmidt, Peer; Milke, Edgar; Binnewies, Michael; Hoffmann, Stefan

    2008-04-01

    The phosphide telluride Ti 2PTe 2 can be synthesised from the elements or from oxides in a thermite type reaction. Both ways have been optimised by consideration of the thermodynamic behaviour of the compound. Hence, the investigation of phase equilibria in the ternary system Ti/P/Te and of the thermal decomposition of Ti 2PTe 2 was necessary. This investigation was performed by using different experimental approaches as total pressure measurements, thermal analysis and mass spectrometry. The results were supported and further analysed by thermodynamic modelling of the ternary system. It was shown that Ti 2PTe 2(s) decomposes to Ti 2P (s) and Te 2(g) in six consecutive steps. The growth of single crystals of Ti 2PTe 2 is thermodynamically described as a chemical vapour transport with TiCl 4(g) acting as the transport agent.

  14. An approach to preparing porous and hollow metal phosphides with higher hydrodesulfurization activity

    NASA Astrophysics Data System (ADS)

    Song, Limin; Zhang, Shujuan; Wei, Qingwu

    2011-06-01

    This paper describes an effective method for the synthesis of metal phosphides. Bulk and supported Ni 2P, Cu 3P, and CoP were prepared by thermal treatment of metal and the amorphous red phosphorus mixtures. Porous and hollow Ni 2P particles were also synthesized successfully using this method. The structural properties of these products are investigated using X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), inductively coupled plasma (ICP-AES) and X-ray photoemission spectroscopy (XPS). A rational mechanism was proposed for the selective formation of Ni 2P particles. In experimental conditions, the Ni 2P/SiO 2 catalyst exhibits excellent hydrodesulfurization (HDS) activity for dibenzothiophene (DBT).

  15. Redox mechanism in the binary transition metal phosphide Cu3P

    NASA Astrophysics Data System (ADS)

    Mauvernay, B.; Doublet, M.-L.; Monconduit, L.

    2006-05-01

    The electrochemical behaviour of the binary transition metal phosphide Cu3P towards lithium is investigated through galvano- and potentiostatic measurements. Obtained through high-temperature synthesis, this system shows a better volumetric capacity than graphite and a good capacity retention. In situ X-ray diffraction and first-principles electronic structure calculations are combined with the electrochemical results to show that the complete insertion of 3Li+ in the Cu3P electrode proceeds with the formation of three intermediate phases of lithium composition LixCu(3-x)P (x=1,2,3). The extra capacity previously observed in discharge is now clearly assigned to lithium insertion into the CuP2 impurity and to SEI reactions.

  16. Aluminum phosphide poisoning: Possible role of supportive measures in the absence of specific antidote

    PubMed Central

    Agrawal, Vijay Kumar; Bansal, Abhishek; Singh, Ranjeet Kumar; Kumawat, Bhanwar Lal; Mahajan, Parul

    2015-01-01

    Aluminum phosphide (ALP) poisoning is one of the major causes of suicidal deaths. Toxicity by ALP is caused by the liberation of phosphine gas, which rapidly causes cell hypoxia due to inhibition of oxidative phosphorylation, leading to circulatory failure. Treatment of ALP toxicity is mainly supportive as there is no specific antidote. We recently managed 7 cases of ALP poisoning with severe hemodynamic effects. Patients were treated with supportive measures including gastric lavage with diluted potassium permanganate, coconut oil and sodium-bicarbonate first person account should be avoided in a scientific paper. Intravenous magnesium sulfate, proper hemodynamic monitoring and vasopressors. Four out of 7 survived thus suggesting a role of such supportive measures in the absence of specific antidote for ALP poisoning. PMID:25722553

  17. High-efficiency indium tin oxide/indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Li, X.; Wanlass, M. W.; Gessert, T. A.; Emery, K. A.; Coutts, T. J.

    1989-01-01

    Improvements in the performance of indium tin oxide (ITO)/indium phosphide solar cells have been realized by the dc magnetron sputter deposition of n-ITO onto an epitaxial p/p(+) structure grown on commercial p(+) bulk substrates. The highest efficiency cells were achieved when the surface of the epilayer was exposed to an Ar/H2 plasma before depositing the bulk of the ITO in a more typical Ar/O2 plasma. With H2 processing, global efficiencies of 18.9 percent were achieved. It is suggested that the excellent performance of these solar cells results from the optimization of the doping, thickness, transport, and surface properties of the p-type base, as well as from better control over the ITO deposition procedure.

  18. Effect of emitter parameter variation on the performance of heteroepitaxial indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Jain, R. K.; Flood, D. J.

    1990-01-01

    Metalorganic chemical-vapor-deposited heteroepitaxial indium phosphide (InP) solar cell experimental results were simulated by using a PC-1D computer model. The effect of emitter parameter variation on the performance of n(+)/p/p(+) heteroepitaxial InP/GaAs solar cell was presented. The thinner and lighter doped emitters were observed to offer higher cell efficiencies. The influence of emitter thickness and minority carrier diffusion length on the cell efficiency with respect to dislocation density was studied. Heteroepitaxial cells with efficiencies similar to present day homojunction InP efficiencies (greaater than 16 percent AM0) were shown to be attainable if a dislocation density lower than 10(exp 6)/sq cm could be achieved. A realistic optimized design study yielded InP solar cells of over 22 percent AM0 efficiency at 25 C.

  19. Effect of InAlAs window layer on efficiency of indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Jain, Raj K.; Landis, Geoffrey A.

    1992-01-01

    Indium phosphide (InP) solar cell efficiencies are limited by surface recombination. The effect of a wide bandgap, lattice-matched indium aluminum arsenide (In(0.52)Al(0.48)As) window layer on the performance of InP solar cells was investigated by using the numerical code PC-1D. The p(+)n InP solar cell performance improved significantly with the use of the window layer. No improvement was seen for the n(+)p InP cells. The cell results were explained by the band diagram of the heterostructure and the conduction band energy discontinuity. The calculated current voltage and internal quantum efficiency results clearly demonstrated that In(0.52)Al(0.48)As is a very promising candidate for a window layer material for p(+)n InP solar cells.

  20. Effect of emitter parameter variation on the performance of heteroepitaxial indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Jain, Raj K.; Flood, Dennis J.

    1990-01-01

    Metallorganic chemical-vapor-deposited heteroepitaxial indium phosphide (InP) solar cell experimental results were simulated by using a PC-1D computer model. The effect of emitter parameter variation on the performance of n(+)/p/p(+) heteroepitaxial InP/GaAs solar cell was presented. The thinner and lighter doped emitters were observed to offer higher cell efficiencies. The influence of emitter thickness and minority carrier diffusion length on the cell efficiency with respect to dislocation density was studied. Heteroepitaxial cells with efficiencies similar to present day homojunction InP efficiencies (greater than 16 percent AMO) were shown to be attainable if a dislocation density lower than 10(exp 6)/sq cm could be achieved. A realistic optimized design study yielded InP solar cells of over 22 percent AMO efficiency at 25 C.

  1. Effect of InAlAs window layer on the efficiency of indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Jain, R. K.; Landis, G. A.

    1991-01-01

    Indium phosphide (InP) solar cell efficiencies are limited by surface recombination. The effect of a wide-bandgap lattice-matched indium aluminum arsenide (In0.52Al0.48As) window layer on the performance of InP solar cells was investigated using a numerical code PC-1D. The p(+)n InP solar cell performance improves significantly with the use of a window layer. No improvement is seen for n(+)p InP cells. Cell results are explained by the band diagram of the heterostructure and the conduction-band energy discontinuity. The calculated I-V and internal quantum efficiency results clearly demonstrate that In0.52Al0.48As is a promising candidate as a window layer material for p(+)n InP solar cells.

  2. Treatment of Aluminium Phosphide Poisoning with a Combination of Intravenous Glucagon, Digoxin and Antioxidant Agents.

    PubMed

    Oghabian, Zohreh; Mehrpour, Omid

    2016-08-01

    Aluminium phosphide (AlP) is used to protect stored grains from rodents. It produces phosphine gas (PH3), a mitochondrial poison thought to cause toxicity by blocking the cytochrome c oxidase enzyme and inhibiting oxidative phosphorylation, which results in cell death. AlP poisoning has a high mortality rate among humans due to the rapid onset of cardiogenic shock and metabolic acidosis, despite aggressive treatment. We report a 21-year-old male who was referred to the Afzalipour Hospital, Kerman, Iran, in 2015 after having intentionally ingested a 3 g AlP tablet. He was successfully treated with crystalloid fluids, vasopressors, sodium bicarbonate, digoxin, glucagon and antioxidant agents and was discharged from the hospital six days after admission in good clinical condition. For the treatment of AlP poisoning, the combination of glucagon and digoxin with antioxidant agents should be considered. However, evaluation of further cases is necessary to optimise treatment protocols. PMID:27606117

  3. Treatment of Aluminium Phosphide Poisoning with a Combination of Intravenous Glucagon, Digoxin and Antioxidant Agents

    PubMed Central

    Oghabian, Zohreh; Mehrpour, Omid

    2016-01-01

    Aluminium phosphide (AlP) is used to protect stored grains from rodents. It produces phosphine gas (PH3), a mitochondrial poison thought to cause toxicity by blocking the cytochrome c oxidase enzyme and inhibiting oxidative phosphorylation, which results in cell death. AlP poisoning has a high mortality rate among humans due to the rapid onset of cardiogenic shock and metabolic acidosis, despite aggressive treatment. We report a 21-year-old male who was referred to the Afzalipour Hospital, Kerman, Iran, in 2015 after having intentionally ingested a 3 g AlP tablet. He was successfully treated with crystalloid fluids, vasopressors, sodium bicarbonate, digoxin, glucagon and antioxidant agents and was discharged from the hospital six days after admission in good clinical condition. For the treatment of AlP poisoning, the combination of glucagon and digoxin with antioxidant agents should be considered. However, evaluation of further cases is necessary to optimise treatment protocols. PMID:27606117

  4. Strain tunable electronic and magnetic properties of pristine and semihydrogenated hexagonal boron phosphide

    SciTech Connect

    Yu, Jin; Guo, Wanlin

    2015-01-26

    Tunable electromagnetic properties of pristine two-dimensional boron phosphide (h-BP) nanosheet and its semihydrogenated structure were studied by density functional theory computations. In sharp contrast to previously reported tensile strain-induced red shift in two-dimensional semiconductors, the direct gap of h-BP undergoes blue shift under biaxial tensile strain. Once semihydrogenated, the h-BP not only transform from the nonmagnetic semiconductor into metal which is spin-resolved but also exhibits linear response between the magnetic moment and biaxial strain with a slope up to 0.005 μB/1%. These findings provide a simple and effective route to tune the electronic and magnetic properties of h-BP nanostructures in a wide range and should inspire experimental enthusiasm.

  5. Aluminum phosphide poisoning: Possible role of supportive measures in the absence of specific antidote.

    PubMed

    Agrawal, Vijay Kumar; Bansal, Abhishek; Singh, Ranjeet Kumar; Kumawat, Bhanwar Lal; Mahajan, Parul

    2015-02-01

    Aluminum phosphide (ALP) poisoning is one of the major causes of suicidal deaths. Toxicity by ALP is caused by the liberation of phosphine gas, which rapidly causes cell hypoxia due to inhibition of oxidative phosphorylation, leading to circulatory failure. Treatment of ALP toxicity is mainly supportive as there is no specific antidote. We recently managed 7 cases of ALP poisoning with severe hemodynamic effects. Patients were treated with supportive measures including gastric lavage with diluted potassium permanganate, coconut oil and sodium-bicarbonate first person account should be avoided in a scientific paper. Intravenous magnesium sulfate, proper hemodynamic monitoring and vasopressors. Four out of 7 survived thus suggesting a role of such supportive measures in the absence of specific antidote for ALP poisoning. PMID:25722553

  6. Structure characterization and strain relief analysis in CVD growth of boron phosphide on silicon carbide

    NASA Astrophysics Data System (ADS)

    Li, Guoliang; Abbott, Julia K. C.; Brasfield, John D.; Liu, Peizhi; Dale, Alexis; Duscher, Gerd; Rack, Philip D.; Feigerle, Charles S.

    2015-02-01

    Boron phosphide (BP) is a material of interest for development of a high-efficiency solid-state thermal neutron detector. For a thick film-based device, microstructure evolution is key to the engineering of material synthesis. Here, we report epitaxial BP films grown on silicon carbide with vicinal steps and provide a detailed analysis of the microstructure evolution and strain relief. The BP film is epitaxial in the near-interface region but deviates from epitaxial growth as the film develops. Defects such as coherent and incoherent twin boundaries, dislocation loops, stacking faults concentrate in the near-interface region and segment this region into small domains. The formation of defects in this region do not fully release the strain originated from the lattice mismatch. Large grains emerge above the near-interface region and grain boundaries become the main defects in the upper part of the BP film.

  7. Materials Development for Boron Phosphide Based Neutron Detectors: Final Technical Report

    SciTech Connect

    Edgar, James Howard

    2014-09-12

    The project goal was to improve the quality of boron phosphide (BP) by optimizing its epitaxial growth on single crystal substrates and by producing bulk BP single crystals with low dislocation densities. BP is potentially a good semiconductor for high efficiency solid state neutron detectors by combining neutron capture and charge creation within the same volume. The project strategy was to use newly available single crystal substrates, silicon carbide and aluminum nitride, engineered to produce the best film properties. Substrate variables included the SiC polytype, crystallographic planes, misorientation of the substrate surface (tilt direction and magnitude) from the major crystallographic plane, and surface polarity (Si and C). The best films were (111)BP on silicon-face (0001) 4H-SiC misoriented 4° in the [1-100] direction, and BP on (100) and (111) 3C-SiC/Si; these substrates resulted in films that were free of in-plane twin defects, as determined by x-ray topography. The impact of the deposition temperature was also assessed: increasing the temperature from 1000 °C to 1200 °C produced films that were more ordered and more uniform, and the size of individual grains increased by more than a factor of twenty. The BP films were free of other compounds such as icosahedral boron phosphide (B12P2) over the entire temperature range, as established by Raman spectroscopy. The roughness of the BP films was reduced by increasing the phosphine to diborane ratio from 50 to 200. Bulk crystals were grown by reacting boron dissolved in nickel with phosphorus vapor to precipitate BP. Crystals with dimensions up to 2 mm were produced.

  8. Process Development of Gallium Nitride Phosphide Core-Shell Nanowire Array Solar Cell

    NASA Astrophysics Data System (ADS)

    Chuang, Chen

    Dilute Nitride GaNP is a promising materials for opto-electronic applications due to its band gap tunability. The efficiency of GaNxP1-x /GaNyP1-y core-shell nanowire solar cell (NWSC) is expected to reach as high as 44% by 1% N and 9% N in the core and shell, respectively. By developing such high efficiency NWSCs on silicon substrate, a further reduction of the cost of solar photovoltaic can be further reduced to 61$/MWh, which is competitive to levelized cost of electricity (LCOE) of fossil fuels. Therefore, a suitable NWSC structure and fabrication process need to be developed to achieve this promising NWSC. This thesis is devoted to the study on the development of fabrication process of GaNxP 1-x/GaNyP1-y core-shell Nanowire solar cell. The thesis is divided into two major parts. In the first parts, previously grown GaP/GaNyP1-y core-shell nanowire samples are used to develop the fabrication process of Gallium Nitride Phosphide nanowire solar cell. The design for nanowire arrays, passivation layer, polymeric filler spacer, transparent col- lecting layer and metal contact are discussed and fabricated. The property of these NWSCs are also characterized to point out the future development of Gal- lium Nitride Phosphide NWSC. In the second part, a nano-hole template made by nanosphere lithography is studied for selective area growth of nanowires to improve the structure of core-shell NWSC. The fabrication process of nano-hole templates and the results are presented. To have a consistent features of nano-hole tem- plate, the Taguchi Method is used to optimize the fabrication process of nano-hole templates.

  9. Rapid adaptation of some phytoplankton species to osmium as a result of spontaneous mutations.

    PubMed

    Marvá, Fernando; García-Balboa, Camino; Baselga-Cervera, Beatriz; Costas, Eduardo

    2014-03-01

    To understand the vulnerability of individual species to anthropogenic contamination, it is important to evaluate the different abilities of phytoplankton to respond to environmental changes induced by pollution. The ability of a species to adapt, rather than its initial tolerance, is the basis for survival under rapidly increasing levels of anthropogenic contamination. High doses of osmium (Os) cause massive destruction of diverse phytoplankton groups. In this study, we found that the coastal chlorophyte Tetraselmis suecica and the continental chlorophyte Dictyosphaerium chlorelloides were able to adapt to a lethal dose of Os. In these species, Os-resistant cells arose as a result of rare spontaneous mutations (at rates of approximately 10(-6) mutants per cell division) that occurred before exposure to Os. The mutants remained in the microalgal populations by means of mutation-selection balance. The huge size of phytoplankton populations ensures that there are always enough Os-resistant mutants to guarantee the survival of the population under Os pollution. In contrast, we observed that neither a haptophyte species from open ocean regions nor a cyanobacterium from continental freshwater were able to adapt to the lethal Os dose. Adaptation of phytoplankton to Os contamination is relevant because industrial activities are leading to a rapid increase in Os pollution worldwide. PMID:24357237

  10. The most incompressible metal osmium at static pressures above 750 gigapascals

    NASA Astrophysics Data System (ADS)

    Dubrovinsky, L.; Dubrovinskaia, N.; Bykova, E.; Bykov, M.; Prakapenka, V.; Prescher, C.; Glazyrin, K.; Liermann, H.-P.; Hanfland, M.; Ekholm, M.; Feng, Q.; Pourovskii, L. V.; Katsnelson, M. I.; Wills, J. M.; Abrikosov, I. A.

    2015-09-01

    Metallic osmium (Os) is one of the most exceptional elemental materials, having, at ambient pressure, the highest known density and one of the highest cohesive energies and melting temperatures. It is also very incompressible, but its high-pressure behaviour is not well understood because it has been studied so far only at pressures below 75 gigapascals. Here we report powder X-ray diffraction measurements on Os at multi-megabar pressures using both conventional and double-stage diamond anvil cells, with accurate pressure determination ensured by first obtaining self-consistent equations of state of gold, platinum, and tungsten in static experiments up to 500 gigapascals. These measurements allow us to show that Os retains its hexagonal close-packed structure upon compression to over 770 gigapascals. But although its molar volume monotonically decreases with pressure, the unit cell parameter ratio of Os exhibits anomalies at approximately 150 gigapascals and 440 gigapascals. Dynamical mean-field theory calculations suggest that the former anomaly is a signature of the topological change of the Fermi surface for valence electrons. However, the anomaly at 440 gigapascals might be related to an electronic transition associated with pressure-induced interactions between core electrons. The ability to affect the core electrons under static high-pressure experimental conditions, even for incompressible metals such as Os, opens up opportunities to search for new states of matter under extreme compression.

  11. The most incompressible metal osmium at static pressures above 750 gigapascals.

    PubMed

    Dubrovinsky, L; Dubrovinskaia, N; Bykova, E; Bykov, M; Prakapenka, V; Prescher, C; Glazyrin, K; Liermann, H-P; Hanfland, M; Ekholm, M; Feng, Q; Pourovskii, L V; Katsnelson, M I; Wills, J M; Abrikosov, I A

    2015-09-10

    Metallic osmium (Os) is one of the most exceptional elemental materials, having, at ambient pressure, the highest known density and one of the highest cohesive energies and melting temperatures. It is also very incompressible, but its high-pressure behaviour is not well understood because it has been studied so far only at pressures below 75 gigapascals. Here we report powder X-ray diffraction measurements on Os at multi-megabar pressures using both conventional and double-stage diamond anvil cells, with accurate pressure determination ensured by first obtaining self-consistent equations of state of gold, platinum, and tungsten in static experiments up to 500 gigapascals. These measurements allow us to show that Os retains its hexagonal close-packed structure upon compression to over 770 gigapascals. But although its molar volume monotonically decreases with pressure, the unit cell parameter ratio of Os exhibits anomalies at approximately 150 gigapascals and 440 gigapascals. Dynamical mean-field theory calculations suggest that the former anomaly is a signature of the topological change of the Fermi surface for valence electrons. However, the anomaly at 440 gigapascals might be related to an electronic transition associated with pressure-induced interactions between core electrons. The ability to affect the core electrons under static high-pressure experimental conditions, even for incompressible metals such as Os, opens up opportunities to search for new states of matter under extreme compression. PMID:26302297

  12. Lattice strain of osmium diboride under high pressure and nonhydrostatic stress

    SciTech Connect

    Kavner, Abby; Weinberger, Michelle B.; Shahar, Anat; Cumberland, Robert W.; Levine, Jonathan B.; Kaner, Richard B.; Tolbert, Sarah H.

    2012-01-01

    The lattice strain behavior of osmium diboride—a member of a group of third-row transition metal borides associated with hard/superhard behavior—has been studied using radial diffraction in a diamond anvil cell under high pressure and non-hydrostatic stress. We interpret the average values of the measured lattice strains as a lower-bound to the lattice-plane dependent yield strengths using existing estimates for the elastic constants of OsB2, with a yield strength of 11 GPa at 27.5 GPa of hydrostaticpressure. The measured differential lattice strains show significant plane-dependent anisotropy, with the (101) lattice plane showing the largest differential strain and the (001) lattice plane showing the least strain. At the highest pressure, the a-axis develops a larger compressive strain and supports a larger differential strain than either the b or c axes. This causes an increase in the c/a ratio and a decrease in the a/b ratio especially in the maximum stress direction. The large strength anisotropy of this material points to possible ways to modulate directional mechanical properties by taking advantage of the interplay between aggregate polycrystalline texture with directional mechanical properties.

  13. Rhenium-osmium and samarium-neodymium isotopic systematics of the stillwater complex

    USGS Publications Warehouse

    Lambert, D.D.; Morgan, J.W.; Walker, R.J.; Shirey, S.B.; Carlson, R.W.; Zientek, M.L.; Koski, M.S.

    1989-01-01

    Isotopic data for the Stillwater Complex, Montana , which formed about 2700 Ma (million years ago), were obtained to evaluate the role of magma mixing in the formation of strategic platinum-group element (PGE) ore deposits. Neodymium and osmium isotopic data indicate that the intrusion formed from at least two geochemically distinct magmas. Ultramafic affinity (U-type) magmas had initial ??Nd of -0.8 to -3.2 and a chondritic initial 187Os/186Os ratio of ???0.88, whereas anorthositic affinity (A-type) magmas had ??Nd of -0.7 to +1.7 and an initial 187Os/186Os ratio of ???1.13. These data suggest that U-type magmas were derived from a lithospheric mantle source containing recycled crustal materials whereas A-type magmas originated either by crustal contamination of basaltic magmas or by partial melting of basalt in the lower crust. The Nd and Os isotopic data also suggest that Os, and probably the other PGEs in ore horizons such as the J-M Reef, was derived from A-type magmas. The Nd and Os isotopic heterogeneity observed in rocks below the J-M Reef also suggests that A-type magmas were injected into the Stillwater U-type magma chamber at several stages during the development of the Ultramafic series.

  14. Alkyl Chain Growth on a Transition Metal Center: How Does Iron Compare to Ruthenium and Osmium?

    PubMed

    Sainna, Mala A; de Visser, Sam P

    2015-01-01

    Industrial Fischer-Tropsch processes involve the synthesis of hydrocarbons usually on metal surface catalysts. On the other hand, very few homogeneous catalysts are known to perform a Fischer-Tropsch style of reaction. In recent work, we established the catalytic properties of a diruthenium-platinum carbene complex, [(CpRu)₂(μ²-H) (μ²-NHCH₃)(μ³-C)PtCH₃(P(CH₃)₃)₂](CO)n⁺ with n=0, 2 and Cp=η⁵-C₅(CH₃)₅, and showed it to react efficiently by initial hydrogen atom transfer followed by methyl transfer to form an alkyl chain on the Ru-center. In particular, the catalytic efficiency was shown to increase after the addition of two CO molecules. As such, this system could be viewed as a potential homogeneous Fischer-Tropsch catalyst. Herein, we have engineered the catalytic center of the catalyst and investigated the reactivity of trimetal carbene complexes of the same type using iron, ruthenium and osmium at the central metal scaffold. The work shows that the reactivity should increase from diosmium to diruthenium to diiron; however, a non-linear trend is observed due to multiple factors contributing to the individual barrier heights. We identified all individual components of these reaction steps in detail and established the difference in reactivity of the various complexes. PMID:26426009

  15. Ring opening of strained-ring heterocycles containing nitrogen by an osmium cluster complex

    SciTech Connect

    Adams, R.D.; Chen, Gong

    1992-11-01

    The osmium cluster complex Os{sub 3}(CO){sub 10}({mu}-NCH{sub 2}CH{sub 2}CH{sub 2})({mu}-H) (1) was obtained in 34% yield from the reaction of Os{sub 3}(CO){sub 10}(NCMe){sub 2} with azetidine. Complex 1 was characterized crystallographically and shown to contain a four-membered NCH{sub 2}CH{sub 2}CH{sub 2} ring bridging two of the metal atoms via the nitrogen atom. When heated to 125{degrees}C, 1 was transformed to the new complex Os{sub 3}(CO){sub 10}[{mu}-N=C(H)Et]({mu}-H) (2; 27% yield) by an opening of the four-membered ring and a hydrogen shift. Crystal data: for 1, space group P2{sub 1}/c, a = 8.793 (2) A, b = 16.265 (2) A, c = 13.766 (4) A, {Beta} = 110.56 (1){degrees}, Z = 4, 1872 reflections, R = 0.039; for 2, space group P1, a = 92.73 (2){degrees}, {Beta} = 99.03 (2){degrees}, {gamma} = 81.52 (2){degrees}, Z = 6, 4862 reflections, R = 0.024. 16 refs. 2 figs.

  16. Coronary wall imaging in mice using osmium tetroxide and micro-computed tomography

    NASA Astrophysics Data System (ADS)

    Kozlowski, Megan; Donohue, Danielle; Chen, Marcus; Daniels, Mathew; Connelly, Patricia; Jeffries, Kenneth; Clevenger, Randall; Wen, Han H.; Pai, Vinay M.

    2011-07-01

    Coronary artery disease (CAD) is a major cause of death in the United States and results from the accumulation of atherosclerotic plaques in the arteries of the heart. Plaques accumulate as the result of the retention of low-density lipoprotein (LDL) particles in the sub-endothelium of the arterial wall. In mouse aorta, these lesions form primarily at the branching sites or bifurcations. However, in the coronary system, data has shown that late-stage plaque formation occurs throughout the proximal segments of the arteries. In order to better understand plaque formation in the coronary arteries, we have developed an osmium tetroxide (OsO4) stained coronary wall imaging protocol performed using microcomputed tomography (microCT). OsO4 is a heavy metal contrast agent that readily binds to lipids. Our data in 3- to 25-week old C57BL6 wild-type mice shows that the coronary vessel walls are highlighted by the use of the contrast agent. We expect that this combination of OsO4 and microCT will allow us to investigate the coronary artery wall in atherogenesis models of mice to characterize plaque formation.

  17. Alkyl Chain Growth on a Transition Metal Center: How Does Iron Compare to Ruthenium and Osmium?

    PubMed Central

    Sainna, Mala A.; de Visser, Sam P.

    2015-01-01

    Industrial Fischer-Tropsch processes involve the synthesis of hydrocarbons usually on metal surface catalysts. On the other hand, very few homogeneous catalysts are known to perform a Fischer-Tropsch style of reaction. In recent work, we established the catalytic properties of a diruthenium-platinum carbene complex, [(CpRu)2(μ2-H)(μ2-NHCH3)(μ3-C)PtCH3(P(CH3)3)2](CO)n+ with n = 0, 2 and Cp = η5-C5(CH3)5, and showed it to react efficiently by initial hydrogen atom transfer followed by methyl transfer to form an alkyl chain on the Ru-center. In particular, the catalytic efficiency was shown to increase after the addition of two CO molecules. As such, this system could be viewed as a potential homogeneous Fischer-Tropsch catalyst. Herein, we have engineered the catalytic center of the catalyst and investigated the reactivity of trimetal carbene complexes of the same type using iron, ruthenium and osmium at the central metal scaffold. The work shows that the reactivity should increase from diosmium to diruthenium to diiron; however, a non-linear trend is observed due to multiple factors contributing to the individual barrier heights. We identified all individual components of these reaction steps in detail and established the difference in reactivity of the various complexes. PMID:26426009

  18. Highly fluorous complexes of ruthenium and osmium and their solubility in supercritical carbon dioxide.

    PubMed

    Berven, Bradley M; Koutsantonis, George A; Skelton, Brian W; Trengove, Robert D; White, Allan H

    2009-12-21

    A series of ruthenium and osmium complexes containing highly fluorous diphosphine ligands (F)P(wedge)P(F) = (F(13)C(6)C(6)H(4)-p)(2)P(CH(2))(2)P(p-C(6)H(4)C(6)F(13))(2) (dfppe) and (F(13)C(6)C(6)H(4)-p)(2)P(CH(2))(3)P(p-C(6)H(4)C(6)F(13))(2) (dfppp) has been prepared. The fluorous diphosphine ligands incorporate four C(6)F(13) "fluoro-ponytails", and these have been effective in solubilizing the complexes in supercritical carbon dioxide (scCO(2)). Precise solubility measurements in scCO(2) were performed for some of the complexes. The new complexes [MX(2)((F)P(wedge)P(F))(2)] and [MX((F)P(wedge)P(F))(eta-C(5)H(5))], M = Ru, Os, X = Cl, Br, have been characterized by a number of spectroscopic techniques and their electrochemical properties measured, three of the ruthenium complexes also being characterized by single-crystal X-ray studies. The noncovalent interactions observed in the X-ray structures have been analyzed by the Hirshfeld surface approach, putting them on a more solid footing. The fluorinated complexes show significantly different solvation properties from those of the analogous unfluorinated compounds, particularly with respect to their behavior in common organic solvents and their good scCO(2) solubility. PMID:19938863

  19. Osmium-191/iridium-191m radionuclide generator using an oxalato osmate parent complex

    SciTech Connect

    Packard, A.B.; Treves, S.T.; O'Brien, G.M.; Lim, K.S.

    1987-10-01

    A new osmium-191/iridium-191m (/sup 191/Os//sup 191/mIr) radionuclide generator has been developed that offers high /sup 191/mIr yield (greater than 20%/ml) and low /sup 191/Os breakthrough (less than 5 X 10(-4)%/ml) when eluted with a solution of 0.001 M oxalic acid and 0.9% (normal) saline. This is the first /sup 191/Os//sup 191/mIr generator that combines the advantages of high /sup 191/mIr yield, extremely low /sup 191/Os breakthrough, and an eluate that does not require buffering prior to injection. These improvements in performance were accomplished through use of the chelate transdioxobisoxalatoosmate(VI) as the parent complex on the generator. The clinical result of the combination of higher yield and lower breakthrough is a 100-fold decrease in the estimated patient radiation dose compared with the same study performed with technetium-99m (/sup 99m/Tc), and the injectable eluate makes the generator easier to use. Acute and subacute toxicity studies performed on this generator eluate have shown no adverse effects attributable to the eluate.

  20. An osmium-191/iridium-191m radionuclide generator using an oxalato osmate parent complex.

    PubMed

    Packard, A B; Treves, S T; O'Brien, G M; Lim, K S

    1987-10-01

    A new osmium-191/iridium-191m (191Os/191mIr) radionuclide generator has been developed that offers high 191mIr yield (greater than 20%/ml) and low 191Os breakthrough (less than 5 X 10(-4)%/ml) when eluted with a solution of 0.001 M oxalic acid and 0.9% (normal) saline. This is the first 191Os/191mIr generator that combines the advantages of high 191mIr yield, extremely low 191Os breakthrough, and an eluate that does not require buffering prior to injection. These improvements in performance were accomplished through use of the chelate transdioxobisoxalatoosmate(VI) as the parent complex on the generator. The clinical result of the combination of higher yield and lower breakthrough is a 100-fold decrease in the estimated patient radiation dose compared with the same study performed with technetium-99m (99mTc), and the injectable eluate makes the generator easier to use. Acute and subacute toxicity studies performed on this generator eluate have shown no adverse effects attributable to the eluate. PMID:3655910

  1. Novel synthesis of dispersed molybdenum and nickel phosphides from thermal carbonization of metal- and phosphorus-containing resins.

    PubMed

    Yao, Zhiwei; Tong, Jin; Qiao, Xue; Jiang, Jun; Zhao, Yu; Liu, Dongmei; Zhang, Yichi; Wang, Haiyan

    2015-11-28

    Dispersed pure phases of MoP and Ni2P nanoparticles supported by carbon were synthesized by carbonization of metal- and phosphorus-containing resins under an inert atmosphere. The solid products and the evolution of gases during the carbonization process were investigated by various techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), N2 adsorption-desorption analysis, and mass spectrometry (MS). The resins underwent two carbonization stages: the low-temperature carbonization stage (<650 °C) and the high-temperature carbonization stage (≥650 °C). There was an initial reduction of Mo and Ni precursors in the low-temperature region. However, the formation of phosphides was observed in the high-temperature carbonization stage, in which Mo(Ni) and POx species were further reacted with the carbonization products (C, H2 and CH4) to yield Mo(Ni) phosphide. Note that compared with the traditional H2-temperature-programmed reduction (H2-TPR) method, this novel synthesis route produced a large amount of CO(x) besides H2O, leading to a lower water vapor pressure. In addition, the residual carbon produced from resin can play a role in bonding of nanoparticle aggregation. Therefore, the better dispersions and higher surface areas of the as-prepared phosphide nanoparticles were attributed to the mitigation of hydrothermal sintering and the intimate contact between phosphide nanoparticles and carbon species. PMID:26501890

  2. Zinc phosphide

    Integrated Risk Information System (IRIS)

    Zinc phoshide ; CASRN 1314 - 84 - 7 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  3. Mechanism Elucidation of the cis–trans Isomerization of an Azole Ruthenium–Nitrosyl Complex and Its Osmium Counterpart

    PubMed Central

    2013-01-01

    Synthesis and X-ray diffraction structures of cis and trans isomers of ruthenium and osmium metal complexes of general formulas (nBu4N)[cis-MCl4(NO)(Hind)], where M = Ru (1) and Os (3), and (nBu4N)[trans-MCl4(NO)(Hind)], where M = Ru (2) and Os (4) and Hind = 1H-indazole are reported. Interconversion between cis and trans isomers at high temperatures (80–130 °C) has been observed and studied by NMR spectroscopy. Kinetic data indicate that isomerizations correspond to reversible first order reactions. The rates of isomerization reactions even at 110 °C are very low with rate constants of 10–5 s–1 and 10–6 s–1 for ruthenium and osmium complexes, respectively, and the estimated rate constants of isomerization at room temperature are of ca. 10–10 s–1. The activation parameters, which have been obtained from fitting the reaction rates at different temperatures to the Eyring equation for ruthenium [ΔHcis-trans‡= 122.8 ± 1.3; ΔHtrans-cis‡= 138.8 ± 1.0 kJ/mol; ΔScis-trans‡= −18.7 ± 3.6; ΔStrans-cis‡= 31.8 ± 2.7 J/(mol·K)] and osmium [ΔHcis-trans‡= 200.7 ± 0.7; ΔHtrans-cis‡= 168.2 ± 0.6 kJ/mol; ΔScis-trans‡= 142.7 ± 8.9; ΔStrans-cis‡= 85.9 ± 3.9 J/(mol·K)] reflect the inertness of these systems. The entropy of activation for the osmium complexes is highly positive and suggests the dissociative mechanism of isomerization. In the case of ruthenium, the activation entropy for the cis to trans isomerization is negative [−18.6 J/(mol·K)], while being positive [31.0 J/(mol·K)] for the trans to cis conversion. The thermodynamic parameters for cis to trans isomerization of [RuCl4(NO)(Hind)]−, viz. ΔH° = 13.5 ± 1.5 kJ/mol and ΔS° = −5.2 ± 3.4 J/(mol·K) indicate the low difference between the energies of cis and trans isomers. The theoretical calculation has been carried out on isomerization of ruthenium complexes with DFT methods. The dissociative, associative, and intramolecular twist isomerization mechanisms have

  4. Mechanism elucidation of the cis-trans isomerization of an azole ruthenium-nitrosyl complex and its osmium counterpart.

    PubMed

    Gavriluta, Anatolie; Büchel, Gabriel E; Freitag, Leon; Novitchi, Ghenadie; Tommasino, Jean Bernard; Jeanneau, Erwann; Kuhn, Paul-Steffen; González, Leticia; Arion, Vladimir B; Luneau, Dominique

    2013-06-01

    Synthesis and X-ray diffraction structures of cis and trans isomers of ruthenium and osmium metal complexes of general formulas (nBu4N)[cis-MCl4(NO)(Hind)], where M = Ru (1) and Os (3), and (nBu4N)[trans-MCl4(NO)(Hind)], where M = Ru (2) and Os (4) and Hind = 1H-indazole are reported. Interconversion between cis and trans isomers at high temperatures (80-130 °C) has been observed and studied by NMR spectroscopy. Kinetic data indicate that isomerizations correspond to reversible first order reactions. The rates of isomerization reactions even at 110 °C are very low with rate constants of 10(-5) s(-1) and 10(-6) s(-1) for ruthenium and osmium complexes, respectively, and the estimated rate constants of isomerization at room temperature are of ca. 10(-10) s(-1). The activation parameters, which have been obtained from fitting the reaction rates at different temperatures to the Eyring equation for ruthenium [ΔH(cis-trans)‡ = 122.8 ± 1.3; ΔH(trans-cis)‡ = 138.8 ± 1.0 kJ/mol; ΔS(cis-trans)‡ = -18.7 ± 3.6; ΔS(trans-cis)‡ = 31.8 ± 2.7 J/(mol·K)] and osmium [ΔH(cis-trans)‡ = 200.7 ± 0.7; ΔH(trans-cis)‡ = 168.2 ± 0.6 kJ/mol; ΔS(cis-trans)‡ = 142.7 ± 8.9; ΔS(trans-cis)‡ = 85.9 ± 3.9 J/(mol·K)] reflect the inertness of these systems. The entropy of activation for the osmium complexes is highly positive and suggests the dissociative mechanism of isomerization. In the case of ruthenium, the activation entropy for the cis to trans isomerization is negative [-18.6 J/(mol·K)], while being positive [31.0 J/(mol·K)] for the trans to cis conversion. The thermodynamic parameters for cis to trans isomerization of [RuCl4(NO)(Hind)]-, viz. ΔH° = 13.5 ± 1.5 kJ/mol and ΔS° = -5.2 ± 3.4 J/(mol·K) indicate the low difference between the energies of cis and trans isomers. The theoretical calculation has been carried out on isomerization of ruthenium complexes with DFT methods. The dissociative, associative, and intramolecular twist isomerization

  5. Investigation of Neutron-Rich Osmium Isotopes in the Reaction 136Xe+208Pb at the Energies Close to Coulomb Barrier

    NASA Astrophysics Data System (ADS)

    Novikov, K.; Kozulin, E.; Dmitriev, S.; Greenlees, P.; Hannape, F.; Itkis, I. M.; Khlebnikov, S.; Knyazheva, G.; Loktev, T.; Maurer, J.; di Nitto, A.; Pakarinen, J.; Ruotsalainen, P.; Sandzelius, M.; Sorri, J.; Trzaska, W. H.; Vardaci, E.; Zagrebaev, V.

    2013-06-01

    At the present time, a great interest is paid to the research of the properties of atomic nuclei (isotopes) located far from the beta stability line. Neutron-rich osmium isotopes of multi-nucleon transfer reactions investigated in this work. The reaction 136Xe+208Pb with energy near Coulomb barrier is used for production osmium isotopes. The CORSAR-V setup was created in framework of our investigations. Method of separation volatile reaction products from non-volatile products was realized from experimental setup. The fist experimental results were obtained at this time.

  6. Osmium-Isotope and Platinum-Group-Element Systematics of Impact-Melt Rocks, Chesapeake Bay Impact Structure, Virginia, USA

    NASA Technical Reports Server (NTRS)

    Lee, Seung Ryeol; Wright Horton, J., Jr.; Walker, Richard J.

    2005-01-01

    Osmium (Os) isotopes and platinum-group elements (PGEs) are useful for geochemically identifying a meteoritic component within impact structures, because meteorites are typically characterized by low (187)Os/(188)Os ratios and high PGE concentrations. In contrast, most types of crustal target rocks have high radiogenic Os and very low PGE concentrations. We have examined Os isotope and PGE systematics of impact-melt rocks and pre-impact target rocks from a 2004 test hole in the late Eocene Chesapeake Bay impact structure and from nearby coreholes. Our goal is to determine the proportion of the projectile component in the melt rock Additional information is included in the original extended abstract.

  7. Abundances and isotopic compositions of rhenium and osmium in pyrite samples from the Huaibei coalfield, Anhui, China

    USGS Publications Warehouse

    Liu, Gaisheng; Chou, C.-L.; Peng, Z.; Yang, G.

    2008-01-01

    Two pyrite samples from the Shihezi Formation (Lower Permian), Huaibei coalfield, Anhui, China, have been analyzed for abundances and isotopic compositions of rhenium and osmium using negative thermal ion mass spectrometry. The Re-Os ages of the pyrites are 64.4 and 226 Ma, which are younger than the formation age of the coal seam. The pyrite samples may consist of pyrite formed at various stages during the history of coal formation. The ??Osvalues of the two pyrite samples are +17 and +18, respectively. Such high ??Osvalues are reported for the first time for recycles crustal materials from a sedimentary basin. ?? Springer-Verlag 2007.

  8. Biological activity of ruthenium and osmium arene complexes with modified paullones in human cancer cells.

    PubMed

    Mühlgassner, Gerhard; Bartel, Caroline; Schmid, Wolfgang F; Jakupec, Michael A; Arion, Vladimir B; Keppler, Bernhard K

    2012-11-01

    In an attempt to combine the ability of indolobenzazepines (paullones) to inhibit cyclin-dependent kinases (Cdks) and that of platinum-group metal ions to interact with proteins and DNA, ruthenium(II) and osmium(II) arene complexes with paullones were prepared, expecting synergies and an increase of solubility of paullones. Complexes with the general formula [M(II)Cl(η(6)-p-cymene)L]Cl, where M=Ru (1, 3) or Os (2, 4), and L=L(1) (1, 2) or L(2) (3, 4), L(1)=N-(9-bromo-7,12-dihydroindolo[3,2-d][1]-benzazepin-6(5H)-yliden-N'-(2-hydroxybenzylidene)azine and L(2)=N-(9-bromo-7,12-dihydroindolo[3,2-d][1]benzazepin-6-yl)-N'-[3-hydroxy-5-(hydroxymethyl)-2-methylpyridin-4-yl-methylene]azinium chloride (L(2)(*)HCl), were now investigated regarding cytotoxicity and accumulation in cancer cells, impact on the cell cycle, capacity of inhibiting DNA synthesis and inducing apoptosis as well as their ability to inhibit Cdk activity. The MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide) assay yielded IC(50) values in the nanomolar to low micromolar range. In accordance with cytotoxicity data, the BrdU assay showed that 1 is the most and 4 the least effective of these compounds regarding inhibition of DNA synthesis. Effects on the cell cycle are minor, although concentration-dependent inhibition of Cdk2/cyclin E activity was observed in cell-free experiments. Induction of apoptosis is most pronounced for complex 1, accompanied by a low fraction of necrotic cells, as observed by annexin V-fluorescein isothiocyanate/propidium iodide staining and flow cytometric analysis. PMID:23037896

  9. Biological activity of ruthenium and osmium arene complexes with modified paullones in human cancer cells

    PubMed Central

    Mühlgassner, Gerhard; Bartel, Caroline; Schmid, Wolfgang F.; Jakupec, Michael A.; Arion, Vladimir B.; Keppler, Bernhard K.

    2012-01-01

    In an attempt to combine the ability of indolobenzazepines (paullones) to inhibit cyclin-dependent kinases (Cdks) and that of platinum-group metal ions to interact with proteins and DNA, ruthenium(II) and osmium(II) arene complexes with paullones were prepared, expecting synergies and an increase of solubility of paullones. Complexes with the general formula [MIICl(η6-p-cymene)L]Cl, where M = Ru (1, 3) or Os (2, 4), and L = L1 (1, 2) or L2 (3, 4), L1 = N-(9-bromo-7,12-dihydroindolo[3,2-d][1]-benzazepin-6(5H)-yliden-N′-(2-hydroxybenzylidene)azine and L2 = N-(9-bromo-7,12-dihydroindolo[3,2-d][1]benzazepin-6-yl)-N′-[3-hydroxy-5-(hydroxymethyl)-2-methylpyridin-4-yl-methylene]azinium chloride (L2*HCl), were now investigated regarding cytotoxicity and accumulation in cancer cells, impact on the cell cycle, capacity of inhibiting DNA synthesis and inducing apoptosis as well as their ability to inhibit Cdk activity. The MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide) assay yielded IC50 values in the nanomolar to low micromolar range. In accordance with cytotoxicity data, the BrdU assay showed that 1 is the most and 4 the least effective of these compounds regarding inhibition of DNA synthesis. Effects on the cell cycle are minor, although concentration-dependent inhibition of Cdk2/cyclin E activity was observed in cell-free experiments. Induction of apoptosis is most pronounced for complex 1, accompanied by a low fraction of necrotic cells, as observed by annexin V–fluorescein isothiocyanate/propidium iodide staining and flow cytometric analysis. PMID:23037896

  10. Seawater osmium isotope evidence for a middle Miocene flood basalt event in ferromanganese crust records

    USGS Publications Warehouse

    Klemm, V.; Frank, M.; Levasseur, S.; Halliday, A.N.; Hein, J.R.

    2008-01-01

    Three ferromanganese crusts from the northeast, northwest and central Atlantic were re-dated using osmium (Os) isotope stratigraphy and yield ages from middle Miocene to the present. The three Os isotope records do not show evidence for growth hiatuses. The reconstructed Os isotope-based growth rates for the sections older than 10??Ma are higher than those determined previously by the combined beryllium isotope (10Be/9Be) and cobalt (Co) constant-flux methods, which results in a decrease in the maximum age of each crust. This re-dating does not lead to significant changes to the interpretation of previously determined radiogenic isotope neodymium, lead (Nd, Pb) time series because the variability of these isotopes was very small in the records of the three crusts prior to 10??Ma. The Os isotope record of the central Atlantic crust shows a pronounced minimum during the middle Miocene between 15 and 12??Ma, similar to a minimum previously observed in two ferromanganese crusts from the central Pacific. For the other two Atlantic crusts, the Os isotope records and their calibration to the global seawater curve for the middle Miocene are either more uncertain or too short and thus do not allow for a reliable identification of an isotopic minimum. Similar to pronounced minima reported previously for the Cretaceous/Tertiary and Eocene/Oligocene boundaries, possible interpretations for the newly identified middle Miocene Os isotope minimum include changes in weathering intensity and/or a meteorite impact coinciding with the formation of the No??rdlinger Ries Crater. It is suggested that the eruption and weathering of the Columbia River flood basalts provided a significant amount of the unradiogenic Os required to produce the middle Miocene minimum. ?? 2008 Elsevier B.V.

  11. Distribution of coniferin in differentiating normal and compression woods using MALDI mass spectrometric imaging coupled with osmium tetroxide vapor treatment.

    PubMed

    Yoshinaga, Arata; Kamitakahara, Hiroshi; Takabe, Keiji

    2016-05-01

    Matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI) was employed to detect monolignol glucosides in differentiating normal and compression woods of two Japanese softwoods, Chamaecyparis obtusa and Cryptomeria japonica Comparison of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry collision-induced dissociation fragmentation analysis and structural time-of-flight (MALDI-TOF CID-FAST) spectra between coniferin and differentiating xylem also confirmed the presence of coniferin in differentiating xylem. However, as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and MALDI-TOF CID-FAST spectra of sucrose were similar to those of coniferin, it was difficult to distinguish the distribution of coniferin and sucrose using MALDI-MSI and collision-induced dissociation measurement only. To solve this problem, osmium tetroxide vapor was applied to sections of differentiating xylem. This vapor treatment caused peak shifts corresponding to the introduction of two hydroxyl groups to the C=C double bond in coniferin. The treatment did not cause a peak shift for sucrose, and therefore was effective in distinguishing coniferin and sucrose. Thus, it was found that MALDI-MSI combined with osmium tetroxide vapor treatment is a useful method to detect coniferin in differentiating xylem. PMID:26507270

  12. Osmium isotopes and silver as tracers of anthropogenic metals in sediments from Massachusetts and Cape Cod bays

    USGS Publications Warehouse

    Ravizza, G.E.; Bothner, Michael H.

    1996-01-01

    High concentrations of osmium (Os) and silver (Ag) and low 187Os/186Os ratios in Boston sewage make these elements sensitive tracers of the influence of sewage on marine sediments in Massachusetts and Cape Cod bays. Pristine marine sediments have Ag concentrations more than 200 times lower than sewage sludge, Os concentrations 10-40 times lower, and 187Os/186Os ratios six times higher. Surface sediments from both Massachusetts and Cape Cod bays exhibit both high Ag concentrations and low 187Os/186Os ratios indicating the influence of sewage particles on marine sediments in this region extends some 70 km from the point of sewage release. In detail, the distribution of Os and Ag do not support a model of simple physical mixing of sewage particles with normal marine sediments. Deviations from the mixing model may be the result of fractionation of Os and Ag in the marine environment, and [or] independent temporal variations in the Os and Ag content of the waste stream. The results of this investigation suggest that osmium isotopes may be widely applicable as tracers of the influence of sewage on sediments in estuarine environments and that subtle variations in the isotopic composition of Os in the waste stream may help constrain the sources of Os and other metals delivered to the environment.

  13. Osmium isotopes and silver as tracers of anthropogenic metals in sediments from Massachusetts and Cape Cod bays

    NASA Astrophysics Data System (ADS)

    Ravizza, G. E.; Bothner, M. H.

    1996-08-01

    High concentrations of osmium (Os) and silver (Ag) and low 187Os/ 186Os ratios in Boston sewage make these elements sensitive tracers of the influence of sewage on marine sediments in Massachusetts and Cape Cod bays. Pristine marine sediments have Ag concentrations more than 200 times lower than sewage sludge, Os concentrations 10-40 times lower, and 187OS/ 186Os ratios six times higher. Surface sediments from both Massachusetts and Cape Cod bays exhibit both high Ag concentrations and low 187OS/ 186Os ratios indicating the influence of sewage particles on marine sediments in this region extends some 70 km from the point of sewage release. In detail, the distribution of Os and Ag do not support a model of simple physical mixing of sewage particles with normal marine sediments. Deviations from the mixing model may be the result of fractionation of Os and Ag in the marine environment, and [or] independent temporal variations in the Os and Ag content of the waste stream. The results of this investigation suggest that osmium isotopes may be widely applicable as tracers of the influence of sewage on sediments in estuarine environments and that subtle variations in the isotopic composition of Os in the waste stream may help constrain the sources of Os and other metals delivered to the environment.

  14. Design, synthesis, crystal structure and magnetic properties of novel osmium-based B-site ordered double perovskites

    NASA Astrophysics Data System (ADS)

    Russell, David D.

    Transition metal oxides (TMOs) with face centered cubic arrangement of magnetic ions are composed of triangular sub-lattices. When antiferromagnetic (AFM) interactions of the same strengths between all three pathways in triangular settings are in place, spin constraints cannot be fulfilled simultaneously and the system undergoes geometric magnetic frustration (GMF). The purpose of the work presented in this thesis is to better understand the criteria for a system to undergo GMF. To achieve this, the novel B-site ordered double perovskites Ca2ScOsO6 and Ca2.2Mg0.8 OsO6 were synthesized in polycrystalline form utilizing the conventional solid-state method. The crystal structure of these compounds were characterized through X-ray diffraction, and magnetic properties were explored through magnetic susceptibility measurements. Employing the spin-dimer analysis method, relative magnetic exchange interactions were calculated and modeled. These novel osmium-based B-site ordered double perovskites were then compared to isostructural compounds to study the effects of the osmium oxidation state on crystal structure and the exhibited properties.

  15. Unexpected higher stabilisation of two classical antiaromatic frameworks with a ruthenium fragment compared to the osmium counterpart: origin probed by DFT calculations.

    PubMed

    Wu, Jingjing; Hao, Yulei; An, Ke; Zhu, Jun

    2016-01-01

    Density functional theory (DFT) calculations were carried out to investigate the stability and aromaticity of metallapentalocyclobutadienes. The results reveal unexpected higher stabilisation achieved with a 4d ruthenium fragment compared to the 5d [corrected] osmium counterpart. Moreover, direct 1-3 metal-carbon bonding in the metallabutadiene unit of these two complexes is negligible. PMID:26505956

  16. Effect of dislocations on the open-circuit voltage, short-circuit current and efficiency of heteroepitaxial indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Jain, Raj K.; Flood, Dennis J.

    1990-01-01

    Excellent radiation resistance of indium phosphide solar cells makes them a promising candidate for space power applications, but the present high cost of starting substrates may inhibit their large scale use. Thin film indium phosphide cells grown on Si or GaAs substrates have exhibited low efficiencies, because of the generation and propagation of large number of dislocations. Dislocation densities were calculated and its influence on the open circuit voltage, short circuit current, and efficiency of heteroepitaxial indium phosphide cells was studied using the PC-1D. Dislocations act as predominant recombination centers and are required to be controlled by proper transition layers and improved growth techniques. It is shown that heteroepitaxial grown cells could achieve efficiencies in excess of 18 percent AMO by controlling the number of dislocations. The effect of emitter thickness and surface recombination velocity on the cell performance parameters vs. dislocation density is also studied.

  17. Phase-controllable synthesis of nanosized nickel phosphides and comparison of photocatalytic degradation ability

    NASA Astrophysics Data System (ADS)

    Ni, Yonghong; Jin, Lina; Hong, Jianming

    2011-01-01

    In this paper, we employed a facile hydrothermal route to successfully synthesize nanosized nickel phosphide particles with controlled phases via selecting different surfactants at different temperatures and times. The phases of the as-obtained products were determined by X-ray powder diffraction (XRD) patterns and Rietveld refinement of XRD data. The morphologies of the products were characterized by (high resolution) transmission electron microscopy (HR/TEM) and field emission scanning electron microscopy (FESEM). Experiments indicated that pure Ni2P phase could be prepared when nontoxic red phosphorus and nickel dichloride were used as starting materials in the presence of polyvinylpyrrolidone (PVP, 30 K), sodium dodecylbenzene sulfonate (SDBS), cetyltrimethylammonium bromide (CTAB) or polyethylene glycol 10000 (PEG-10000) at 160 °C for 10 h. When acrylamide (AM) was selected as the surfactant, however, pure Ni12P5 phase could be prepared by prolonging the reaction time to 20 h at 160 °C, or enhancing the reaction temperature to 180 °C for 10 h. Furthermore, the experiments indicated that the pure Ni2P phase possessed a stronger photocatalytic degradation ability than the pure Ni12P5 phase.

  18. Highly stable two-dimensional silicon phosphides: Different stoichiometries and exotic electronic properties

    SciTech Connect

    Huang, Bing; Zhuang, Houlong L.; Yoon, Mina; Sumpter, Bobby G.; Wei, Su-Huai

    2015-03-03

    We report that the discovery of stable two-dimensional, earth-abundant, semiconducting materials is of great interest and may impact future electronic technologies. By combining global structural prediction and first-principles calculations, we have theoretically discovered several previously unknown semiconducting silicon phosphides (SixPy) monolayers, which could be formed stably at the stoichiometries of y/x ≥1. Unexpectedly, some of these compounds, i.e., P-6m2 Si1P1 and Pm Si1P2, have comparable or even lower formation enthalpies than their previously known bulk allotropes. The band gaps (Eg) of SixPy compounds can be dramatically tuned in an extremely wide range (0< Eg < 3 eV) by simply changing the number of layers or applying an in-plane strain. Furthermore, we find that carrier doping can drive the ground state of C2/m Si1P3 from a nonmagnetic state into a robust half-metallic spin-polarized state, originating from its unique valence band structure, which can extend the use of Si-related compounds for spintronics.

  19. Direct Band Gap Gallium Antimony Phosphide (GaSbxP1−x) Alloys

    PubMed Central

    Russell, H. B.; Andriotis, A. N.; Menon, M.; Jasinski, J. B.; Martinez-Garcia, A.; Sunkara, M. K.

    2016-01-01

    Here, we report direct band gap transition for Gallium Phosphide (GaP) when alloyed with just 1–2 at% antimony (Sb) utilizing both density functional theory based computations and experiments. First principles density functional theory calculations of GaSbxP1−x alloys in a 216 atom supercell configuration indicate that an indirect to direct band gap transition occurs at x = 0.0092 or higher Sb incorporation into GaSbxP1−x. Furthermore, these calculations indicate band edge straddling of the hydrogen evolution and oxygen evolution reactions for compositions ranging from x = 0.0092 Sb up to at least x = 0.065 Sb making it a candidate for use in a Schottky type photoelectrochemical water splitting device. GaSbxP1−x nanowires were synthesized by reactive transport utilizing a microwave plasma discharge with average compositions ranging from x = 0.06 to x = 0.12 Sb and direct band gaps between 2.21 eV and 1.33 eV. Photoelectrochemical experiments show that the material is photoactive with p-type conductivity. This study brings attention to a relatively uninvestigated, tunable band gap semiconductor system with tremendous potential in many fields. PMID:26860470

  20. Electronic Structures of Free-Standing Nanowires made from Indirect Bandgap Semiconductor Gallium Phosphide

    NASA Astrophysics Data System (ADS)

    Liao, Gaohua; Luo, Ning; Chen, Ke-Qiu; Xu, H. Q.

    2016-06-01

    We present a theoretical study of the electronic structures of freestanding nanowires made from gallium phosphide (GaP)—a III-V semiconductor with an indirect bulk bandgap. We consider [001]-oriented GaP nanowires with square and rectangular cross sections, and [111]-oriented GaP nanowires with hexagonal cross sections. Based on tight binding models, both the band structures and wave functions of the nanowires are calculated. For the [001]-oriented GaP nanowires, the bands show anti-crossing structures, while the bands of the [111]-oriented nanowires display crossing structures. Two minima are observed in the conduction bands, while the maximum of the valence bands is always at the Γ-point. Using double group theory, we analyze the symmetry properties of the lowest conduction band states and highest valence band states of GaP nanowires with different sizes and directions. The band state wave functions of the lowest conduction bands and the highest valence bands of the nanowires are evaluated by spatial probability distributions. For practical use, we fit the confinement energies of the electrons and holes in the nanowires to obtain an empirical formula.

  1. Pure and carbon-doped boron phosphide (6,0) zigzag nanotube: A computational NMR study

    NASA Astrophysics Data System (ADS)

    Arshadi, S.; Bekhradnia, A. R.; Alipour, F.; Abedini, S.

    2015-11-01

    Calculations were performed for investigation of the properties of the electronic structure of Carbon- Doped Boron Phosphide Nanotube (CDBPNT). Pristine and three models of C-doped structures of (6,0) zigzag BPNT were studied at density functional theory (DFT) in combination with 6-311G* basis set using Gaussian package of program. The calculated parameters reveal that various 11B and 31P nuclei are divided into some layers with equivalent electrostatic properties. The electronic structure properties are highly influenced by replacement of 11B and 31P atoms by 12C atoms in pristine model. Furthermore, the HOMO-LUMO gap energy for suggested doped models (I), (II) and (III) were lower than pure BPNT pristine systems. The dipole moment values of models (II) and (III) were decreased to 1.788 and 1.789, respectively while the dipole moments of model (I) were enhanced to 4.373, in compare to pure pristine one (2.586). The magnitude of changes in Chemical Shielding (CS) tensor parameters revealed that the electron density at the site of 31P was higher than that at the site of 11B due to carbon doping.

  2. Aluminum oxide coating for post-growth photo emission wavelength tuning of indium phosphide nanowire networks

    NASA Astrophysics Data System (ADS)

    Fryauf, David M.; Zhang, Junce; Norris, Kate J.; Diaz Leon, Juan; Kobayashi, Nobuhiko P.

    2013-09-01

    Semiconductor-oxide nanostructure devices can be a very intriguing material platform if optoelectronic properties of the original semiconductor nanostructures can be tuned by explicitly controlling properties of the oxide coating. This paper describes our finding that optical properties of semiconductor nanowires can be tuned by depositing a thin layer of metal oxide. In this experiment, indium phosphide nanowires were grown by metal organic chemical vapor deposition on silicon substrates with gold catalyst. The nanowires formed three-dimensional nanowire networks from which collective optical properties were obtained. The nanowire network was coated with an aluminum oxide thin film deposited by plasma-enhanced atomic layer deposition. We studied the dependence of the peak wavelength of photoluminescence spectra on the thickness of the oxide coatings. We observed continuous blue shift in photoluminescence spectra when the thickness of the oxide coating was increased. The observed blue shift is attributed to the Burstein-Moss effect due to increased carrier concentration in the nanowire cores caused by repulsion from an intrinsic negative fixed charge from the oxide surface. Samples were further characterized by scanning electron microscopy, transmission electron microscopy, and selective area diffractometry in an attempt to explain the physical mechanisms for the blue shift.

  3. Elastic, magnetic and electronic properties of iridium phosphide Ir2P

    DOE PAGESBeta

    Wang, Pei; Wang, Yonggang; Wang, Liping; Zhang, Xinyu; Yu, Xiaohui; Zhu, Jinlong; Wang, Shanmin; Qin, Jiaqian; Leinenweber, Kurt; Chen, Haihua; et al

    2016-02-24

    Cubic (space group: Fm3¯m) iridium phosphide, Ir2P, has been synthesized at high pressure and high temperature. Angle-dispersive synchrotron X-ray diffraction measurements on Ir2P powder using a diamond-anvil cell at room temperature and high pressures (up to 40.6 GPa) yielded a bulk modulus of B0 = 306(6) GPa and its pressure derivative B0'= 6.4(5). Such a high bulk modulus attributed to the short and strongly covalent Ir-P bonds as revealed by first – principles calculations and three-dimensionally distributed [IrP4] tetrahedron network. Indentation testing on a well–sintered polycrystalline sample yielded the hardness of 11.8(4) GPa. Relatively low shear modulus of ~64 GPamore » from theoretical calculations suggests a complicated overall bonding in Ir2P with metallic, ionic, and covalent characteristics. Additionally, a spin glass behavior is indicated by magnetic susceptibility measurements.« less

  4. Recent advances in transition metal phosphide nanomaterials: synthesis and applications in hydrogen evolution reaction.

    PubMed

    Shi, Yanmei; Zhang, Bin

    2016-03-14

    The urgent need of clean and renewable energy drives the exploration of effective strategies to produce molecular hydrogen. With the assistance of highly active non-noble metal electrocatalysts, electrolysis of water is becoming a promising candidate to generate pure hydrogen with low cost and high efficiency. Very recently, transition metal phosphides (TMPs) have been proven to be high performance catalysts with high activity, high stability, and nearly ∼100% Faradic efficiency in not only strong acidic solutions, but also in strong alkaline and neutral media for electrochemical hydrogen evolution. In this tutorial review, an overview of recent development of TMP nanomaterials as catalysts for hydrogen generation with high activity and stability is presented. The effects of phosphorus (P) on HER activity, and their synthetic methods of TMPs are briefly discussed. Then we will demonstrate the specific strategies to further improve the catalytic efficiency and stability of TMPs by structural engineering. Making use of TMPs as cocatalysts and catalysts in photochemical and photoelectrochemical water splitting is also discussed. Finally, some key challenges and issues which should not be ignored during the rapid development of TMPs are pointed out. These strategies and challenges of TMPs are instructive for designing other high-performance non-noble metal catalysts. PMID:26806563

  5. Highly stable two-dimensional silicon phosphides: Different stoichiometries and exotic electronic properties

    DOE PAGESBeta

    Huang, Bing; Zhuang, Houlong L.; Yoon, Mina; Sumpter, Bobby G.; Wei, Su-Huai

    2015-03-03

    We report that the discovery of stable two-dimensional, earth-abundant, semiconducting materials is of great interest and may impact future electronic technologies. By combining global structural prediction and first-principles calculations, we have theoretically discovered several previously unknown semiconducting silicon phosphides (SixPy) monolayers, which could be formed stably at the stoichiometries of y/x ≥1. Unexpectedly, some of these compounds, i.e., P-6m2 Si1P1 and Pm Si1P2, have comparable or even lower formation enthalpies than their previously known bulk allotropes. The band gaps (Eg) of SixPy compounds can be dramatically tuned in an extremely wide range (0< Eg < 3 eV) by simply changingmore » the number of layers or applying an in-plane strain. Furthermore, we find that carrier doping can drive the ground state of C2/m Si1P3 from a nonmagnetic state into a robust half-metallic spin-polarized state, originating from its unique valence band structure, which can extend the use of Si-related compounds for spintronics.« less

  6. Boron phosphide under pressure: In situ study by Raman scattering and X-ray diffraction

    SciTech Connect

    Solozhenko, Vladimir L.; Kurakevych, Oleksandr O.; Le Godec, Yann; Kurnosov, Aleksandr V.; Oganov, Artem R.

    2014-07-21

    Cubic boron phosphide, BP, has been studied in situ by X-ray diffraction and Raman scattering up to 55 GPa at 300 K in a diamond anvil cell. The bulk modulus of B{sub 0} = 174(2) GPa has been established, which is in excellent agreement with our ab initio calculations. The data on Raman shift as a function of pressure, combined with equation-of-state (EOS) data, allowed us to estimate the Grüneisen parameters of the TO and LO modes of zinc-blende structure, γ{sub G}{sup TO }= 1.26 and γ{sub G}{sup LO }= 1.13, just like in the case of other A{sup III}B{sup V} diamond-like phases, for which γ{sub G}{sup TO }> γ{sub G}{sup LO }≅ 1. We also established that the pressure dependence of the effective electro-optical constant α is responsible for a strong change in relative intensities of the TO and LO modes from I{sub TO}/I{sub LO} ∼ 0.25 at 0.1 MPa to I{sub TO}/I{sub LO} ∼ 2.5 at 45 GPa, for which we also find excellent agreement between experiment and theory.

  7. Elastic, magnetic and electronic properties of iridium phosphide Ir2P

    DOE PAGESBeta

    Wang, Pei; Wang, Yonggang; Wang, Liping; Zhang, Xinyu; Yu, Xiaohui; Zhu, Jinlong; Wang, Shanmin; Qin, Jiaqian; Leinenweber, Kurt; Chen, Haihua; et al

    2016-02-24

    Cubic (space group: Fm3¯m) iridium phosphide, Ir2P, has been synthesized at high pressure and high temperature. Angle-dispersive synchrotron X-ray diffraction measurements on Ir2P powder using a diamond-anvil cell at room temperature and high pressures (up to 40.6 GPa) yielded a bulk modulus of B0 = 306(6) GPa and its pressure derivative B0' = 6.4(5). Such a high bulk modulus attributed to the short and strongly covalent Ir-P bonds as revealed by first – principles calculations and three-dimensionally distributed [IrP4] tetrahedron network. Indentation testing on a well–sintered polycrystalline sample yielded the hardness of 11.8(4) GPa. Relatively low shear modulus of ~64more » GPa from theoretical calculations suggests a complicated overall bonding in Ir2P with metallic, ionic, and covalent characteristics. Additionally, a spin glass behavior is indicated by magnetic susceptibility measurements.« less

  8. Electronic Structures of Free-Standing Nanowires made from Indirect Bandgap Semiconductor Gallium Phosphide

    PubMed Central

    Liao, Gaohua; Luo, Ning; Chen, Ke-Qiu; Xu, H. Q.

    2016-01-01

    We present a theoretical study of the electronic structures of freestanding nanowires made from gallium phosphide (GaP)—a III-V semiconductor with an indirect bulk bandgap. We consider [001]-oriented GaP nanowires with square and rectangular cross sections, and [111]-oriented GaP nanowires with hexagonal cross sections. Based on tight binding models, both the band structures and wave functions of the nanowires are calculated. For the [001]-oriented GaP nanowires, the bands show anti-crossing structures, while the bands of the [111]-oriented nanowires display crossing structures. Two minima are observed in the conduction bands, while the maximum of the valence bands is always at the Γ-point. Using double group theory, we analyze the symmetry properties of the lowest conduction band states and highest valence band states of GaP nanowires with different sizes and directions. The band state wave functions of the lowest conduction bands and the highest valence bands of the nanowires are evaluated by spatial probability distributions. For practical use, we fit the confinement energies of the electrons and holes in the nanowires to obtain an empirical formula. PMID:27307081

  9. Elastic, magnetic and electronic properties of iridium phosphide Ir2P

    NASA Astrophysics Data System (ADS)

    Wang, Pei; Wang, Yonggang; Wang, Liping; Zhang, Xinyu; Yu, Xiaohui; Zhu, Jinlong; Wang, Shanmin; Qin, Jiaqian; Leinenweber, Kurt; Chen, Haihua; He, Duanwei; Zhao, Yusheng

    2016-02-01

    Cubic (space group: Fmm) iridium phosphide, Ir2P, has been synthesized at high pressure and high temperature. Angle-dispersive synchrotron X-ray diffraction measurements on Ir2P powder using a diamond-anvil cell at room temperature and high pressures (up to 40.6 GPa) yielded a bulk modulus of B0 = 306(6) GPa and its pressure derivative B0‧ = 6.4(5). Such a high bulk modulus attributed to the short and strongly covalent Ir-P bonds as revealed by first - principles calculations and three-dimensionally distributed [IrP4] tetrahedron network. Indentation testing on a well-sintered polycrystalline sample yielded the hardness of 11.8(4) GPa. Relatively low shear modulus of ~64 GPa from theoretical calculations suggests a complicated overall bonding in Ir2P with metallic, ionic, and covalent characteristics. In addition, a spin glass behavior is indicated by magnetic susceptibility measurements.

  10. Size-dependent magnetic and electrocatalytic properties of nickel phosphide nanoparticles

    NASA Astrophysics Data System (ADS)

    Pan, Yuan; Lin, Yan; Liu, Yunqi; Liu, Chenguang

    2016-03-01

    Nickel phosphide (Ni2P) nanoparticles (NPs) with different sizes were synthesized via thermal decomposition of bis(triphenylphosphine)nickel dichloride precursor in the presence of oleylamine. The size of the as-synthesized Ni2P NPs could easily be controlled by increasing the reaction temperature from 300 to 340 °C. The structure and morphology were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption-desorption and X-ray photoelectron spectroscopy (XPS). Then the influences of the size of the Ni2P NPs on the magnetic and electrocatalytic properties were investigated systematically. The results indicate that the as-synthesized Ni2P NPs exhibit ferromagnetic characteristic at 5 K. The Ni2P NPs with small size exhibit superparamagnetism and the larger size exhibit ferromagnetic characteristic at 300 K. The blocking temperature, saturation magnetization, remanent magnetization and coercivity increased significantly with the increase of size of Ni2P NPs, indicating the strong size effect of Ni2P NPs for magnetic properties. Electrochemical tests indicate that the catalytic activity can be enhanced by decreasing the size of Ni2P NPs. Due to the larger electrochemical active surface area and higher electrical conductivity, the Ni2P NPs with small size exhibit higher electrocatalytic activity. This work suggests that the size of Ni2P NPs is an important factor to affect the magnetic and electrocatalytic properties.

  11. Highly Efficient and Robust Nickel Phosphides as Bifunctional Electrocatalysts for Overall Water-Splitting.

    PubMed

    Li, Jiayuan; Li, Jing; Zhou, Xuemei; Xia, Zhaoming; Gao, Wei; Ma, Yuanyuan; Qu, Yongquan

    2016-05-01

    To search for the efficient non-noble metal based and/or earth-abundant electrocatalysts for overall water-splitting is critical to promote the clean-energy technologies for hydrogen economy. Herein, we report nickel phosphide (NixPy) catalysts with the controllable phases as the efficient bifunctional catalysts for water electrolysis. The phases of NixPy were determined by the temperatures of the solid-phase reaction between the ultrathin Ni(OH)2 plates and NaH2PO2·H2O. The NixPy with the richest Ni5P4 phase synthesized at 325 °C (NixPy-325) delivered efficient and robust catalytic performance for hydrogen evolution reaction (HER) in the electrolytes with a wide pH range. The NixPy-325 catalysts also exhibited a remarkable performance for oxygen evolution reaction (OER) in a strong alkaline electrolyte (1.0 M KOH) due to the formation of surface NiOOH species. Furthermore, the bifunctional NixPy-325 catalysts enabled a highly performed overall water-splitting with ∼100% Faradaic efficiency in 1.0 M KOH electrolyte, in which a low applied external potential of 1.57 V led to a stabilized catalytic current density of 10 mA/cm(2) over 60 h. PMID:27064172

  12. Elastic, magnetic and electronic properties of iridium phosphide Ir2P

    PubMed Central

    Wang, Pei; Wang, Yonggang; Wang, Liping; Zhang, Xinyu; Yu, Xiaohui; Zhu, Jinlong; Wang, Shanmin; Qin, Jiaqian; Leinenweber, Kurt; Chen, Haihua; He, Duanwei; Zhao, Yusheng

    2016-01-01

    Cubic (space group: Fmm) iridium phosphide, Ir2P, has been synthesized at high pressure and high temperature. Angle-dispersive synchrotron X-ray diffraction measurements on Ir2P powder using a diamond-anvil cell at room temperature and high pressures (up to 40.6 GPa) yielded a bulk modulus of B0 = 306(6) GPa and its pressure derivative B0′ = 6.4(5). Such a high bulk modulus attributed to the short and strongly covalent Ir-P bonds as revealed by first – principles calculations and three-dimensionally distributed [IrP4] tetrahedron network. Indentation testing on a well–sintered polycrystalline sample yielded the hardness of 11.8(4) GPa. Relatively low shear modulus of ~64 GPa from theoretical calculations suggests a complicated overall bonding in Ir2P with metallic, ionic, and covalent characteristics. In addition, a spin glass behavior is indicated by magnetic susceptibility measurements. PMID:26905444

  13. Hydrodesulfurization Properties of Rhodium Phosphide: Comparison with Rhodium Metal and Sulfide Catalysts

    SciTech Connect

    Hayes, John R.; Bowker, Richard H.; Gaudette, Amy F.; Smith, Mica C.; Moak, Cameron E.; Nam, Charles Y.; Pratum, Thomas K.; Bussell, Mark E.

    2010-12-15

    Silica-supported rhodium phosphide (Rh2P/SiO2) catalysts were prepared and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), 31P solid-state NMR spectroscopy, X-ray photoelectron spectroscopy (XPS), and chemisorption measurements. XRD and TEM analysis of a 5 wt.% Rh2P/SiO2 catalyst confirmed the presence of well-dispersed Rh2P crystallites on the silica support having an average crystallite size of 10 nm. NMR spectroscopy showed unsupported and silica-supported Rh2P to be metallic and XPS spectroscopy yielded a surface composition of Rh1.94P1.00 that is similar to that expected from the bulk stoichiometry. The 5 wt.% Rh2P/SiO2 catalyst exhibited a higher dibenzothiophene (DBT) hydrodesulfurization (HDS) activity than did Rh/SiO2 and sulfided Rh/SiO2 catalysts having a similar Rh loading and was also more active than a commercial NiAMo/Al2O3 catalyst. The Rh2P/SiO2 catalyst showed excellent stability over a 100 h DBT HDS activity measurement and was more S tolerant than the Rh/SiO2 catalyst. The Rh2P/SiO2 catalyst strongly favored the hydrogenation pathway for DBT HDS, while the Rh/SiO2 and sulfided Rh/SiO2 catalysts favored the direct desulfurization pathway.

  14. Low resistance silver contacts to indium phosphide - Electrical and metallurgical considerations

    NASA Technical Reports Server (NTRS)

    Weizer, Victor G.; Fatemi, Navid S.

    1993-01-01

    The electrical and metallurgical behavior of the Ag-InP contact system has been investigated. Specific contact resistivity (Rc) values in the low 10 exp -6 Ohm sq cm range are readily achieved on n-InP (Si: 1.7 x 10 exp 18/cu cm) after sintering at 400 C for several minutes. The low Rc values, however, are shown to be accompanied by dissolution of InP into the metallization, resulting in device degradation. An analysis of the sinter-induced metallurgical interactions shows this system to be similar to the well-characterized Au-InP system, albeit with fundamental differences. The similarities include the dissociative diffusion of In, the reaction-suppressing effect of SiO2 capping, and especially, the formation of a phosphide layer at the metal-InP interface. The low post-sinter Rc values in the Ag-InP system may be due to the presence of a AgP2 layer at the metal-InP interface; low values of Rc can be achieved without incurring device degrading metallurgical interactions by introducing a thin AgP2 layer between the InP and the current carrying metallization.

  15. Submillimeter sources for radiometry using high power Indium Phosphide Gunn diode oscillators

    NASA Technical Reports Server (NTRS)

    Deo, Naresh C.

    1990-01-01

    A study aimed at developing high frequency millimeter wave and submillimeter wave local oscillator sources in the 60-600 GHz range was conducted. Sources involved both fundamental and harmonic-extraction type Indium Phosphide Gunn diode oscillators as well as varactor multipliers. In particular, a high power balanced-doubler using varactor diodes was developed for 166 GHz. It is capable of handling 100 mW input power, and typically produced 25 mW output power. A high frequency tripler operating at 500 GHz output frequency was also developed and cascaded with the balanced-doubler. A dual-diode InP Gunn diode combiner was used to pump this cascaded multiplier to produce on the order of 0.5 mW at 500 GHz. In addition, considerable development and characterization work on InP Gunn diode oscillators was carried out. Design data and operating characteristics were documented for a very wide range of oscillators. The reliability of InP devices was examined, and packaging techniques to enhance the performance were analyzed. A theoretical study of a new class of high power multipliers was conducted for future applications. The sources developed here find many commercial applications for radio astronomy and remote sensing.

  16. Forward-biased current annealing of radiation degraded indium phosphide and gallium arsenide solar cells

    NASA Technical Reports Server (NTRS)

    Michael, Sherif; Cypranowski, Corinne; Anspaugh, Bruce

    1990-01-01

    The preliminary results of a novel approach to low-temperature annealing of previously irradiated indium phosphide and gallium arsenide solar cells are reported. The technique is based on forward-biased current annealing. The two types of III-V solar cells were irradiated with 1-MeV electrons to a fluence level of (1-10) x 10 to the 14th electrons/sq cm. Several annealing attempts were made, varying all conditions. Optimum annealing was achieved when cells were injected with minority currents at a constant 90 C. The current density for each type of cell was also determined. Significant recovery of degraded parameters was achieved in both cases. However, the InP cell recovery notably exceeded the recovery in GaAs cells. The recovery is thought to be caused by current-stimulated reordering of the radiator-induced displacement damage. Both types of cell were then subjected to several cycles of irradiation and annealing. The results were also very promising. The significant recovery of degraded cell parameters at low temperature might play a major role in considerably extending the end of life of future spacecraft.

  17. Phase-controllable synthesis of nanosized nickel phosphides and comparison of photocatalytic degradation ability.

    PubMed

    Ni, Yonghong; Jin, Lina; Hong, Jianming

    2011-01-01

    In this paper, we employed a facile hydrothermal route to successfully synthesize nanosized nickel phosphide particles with controlled phases via selecting different surfactants at different temperatures and times. The phases of the as-obtained products were determined by X-ray powder diffraction (XRD) patterns and Rietveld refinement of XRD data. The morphologies of the products were characterized by (high resolution) transmission electron microscopy (HR/TEM) and field emission scanning electron microscopy (FESEM). Experiments indicated that pure Ni2P phase could be prepared when nontoxic red phosphorus and nickel dichloride were used as starting materials in the presence of polyvinylpyrrolidone (PVP, 30 K), sodium dodecylbenzene sulfonate (SDBS), cetyltrimethylammonium bromide (CTAB) or polyethylene glycol 10000 (PEG-10000) at 160 °C for 10 h. When acrylamide (AM) was selected as the surfactant, however, pure Ni12P5 phase could be prepared by prolonging the reaction time to 20 h at 160 °C, or enhancing the reaction temperature to 180 °C for 10 h. Furthermore, the experiments indicated that the pure Ni2P phase possessed a stronger photocatalytic degradation ability than the pure Ni12P5 phase. PMID:21049133

  18. Theoretical investigation of indium phosphide buried ring resonators for new angular velocity sensors

    NASA Astrophysics Data System (ADS)

    Dell'Olio, Francesco; Ciminelli, Caterina; Armenise, Mario Nicola

    2013-02-01

    Here, we report the guidelines to be followed to optimize the design of a new angular velocity sensor based on an indium phosphide (InP) ring resonator. Optical properties of InP ring resonators have been investigated together with some significant physical effects for improving the sensor sensitivity. Three-dimensional algorithms have been utilized for the theoretical estimation of the waveguide loss. An optimized waveguide with propagation loss <0.3 dB/cm and a ring resonator with a quality factor of 1.5×106 have been designed. Performance of angular velocity sensors based on InP low-loss ring resonators has been estimated and discussed. Resolution of 10 deg/h and bias drift in the range of 0.1 to 0.3 deg/h have been evaluated for a fully integrated optical gyro including an InGaAsP/InP optical cavity having a footprint less than 24 cm2.

  19. Elastic, magnetic and electronic properties of iridium phosphide Ir2P.

    PubMed

    Wang, Pei; Wang, Yonggang; Wang, Liping; Zhang, Xinyu; Yu, Xiaohui; Zhu, Jinlong; Wang, Shanmin; Qin, Jiaqian; Leinenweber, Kurt; Chen, Haihua; He, Duanwei; Zhao, Yusheng

    2016-01-01

    Cubic (space group: Fmm) iridium phosphide, Ir2P, has been synthesized at high pressure and high temperature. Angle-dispersive synchrotron X-ray diffraction measurements on Ir2P powder using a diamond-anvil cell at room temperature and high pressures (up to 40.6 GPa) yielded a bulk modulus of B0 = 306(6) GPa and its pressure derivative B0' = 6.4(5). Such a high bulk modulus attributed to the short and strongly covalent Ir-P bonds as revealed by first - principles calculations and three-dimensionally distributed [IrP4] tetrahedron network. Indentation testing on a well-sintered polycrystalline sample yielded the hardness of 11.8(4) GPa. Relatively low shear modulus of ~64 GPa from theoretical calculations suggests a complicated overall bonding in Ir2P with metallic, ionic, and covalent characteristics. In addition, a spin glass behavior is indicated by magnetic susceptibility measurements. PMID:26905444

  20. Cobalt Phosphide Hollow Polyhedron as Efficient Bifunctional Electrocatalysts for the Evolution Reaction of Hydrogen and Oxygen.

    PubMed

    Liu, Mengjia; Li, Jinghong

    2016-01-27

    The development of efficient and low-cost hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts for renewable-energy conversion techniques is highly desired. A kind of hollow polyhedral cobalt phosphide (CoP hollow polyhedron) is developed as efficient bifunctional electrocatalysts for HER and OER templated by Co-centered metal-organic frameworks. The as-prepared CoP hollow polyhedron, which have large specific surface area and high porosity providing rich catalytic active sites, show excellent electrocatalytic performances for both HER and OER in acidic and alkaline media, respectively, with onset overpotentials of 35 and 300 mV, Tafel slopes of 59 and 57 mV dec(-1), and a current density of 10 mA cm(-2) at overpotentials of 159 and 400 mV for HER and OER, respectively, which are remarkably superior to those of particulate CoP (CoP particles) and comparable to those of commercial noble-metal catalysts. In addition, the CoP hollow polyhedron also show good durability after long-term operations. PMID:26711014

  1. Highly stable two-dimensional silicon phosphides: Different stoichiometries and exotic electronic properties

    NASA Astrophysics Data System (ADS)

    Huang, Bing; Zhuang, Houlong L.; Yoon, Mina; Sumpter, Bobby G.; Wei, Su-Huai

    2015-03-01

    The discovery of stable two-dimensional, earth-abundant, semiconducting materials is of great interest and may impact future electronic technologies. By combining global structural prediction and first-principles calculations, we have theoretically discovered several semiconducting silicon phosphide (SixPy ) monolayers, which could be formed stably at the stoichiometries of y /x ≥1 . Interestingly, some of these compounds, i.e., P -6 m 2 Si1P1 and P m Si1P2 , have comparable or even lower formation enthalpies than their known allotropes. The band gaps (Eg) of SixPy compounds can be dramatically tuned in an extremely wide range (0

  2. Growth and Photoelectrochemical Energy Conversion of Wurtzite Indium Phosphide Nanowire Arrays.

    PubMed

    Kornienko, Nikolay; Gibson, Natalie A; Zhang, Hao; Eaton, Samuel W; Yu, Yi; Aloni, Shaul; Leone, Stephen R; Yang, Peidong

    2016-05-24

    Photoelectrochemical (PEC) water splitting into hydrogen and oxygen is a promising strategy to absorb solar energy and directly convert it into a dense storage medium in the form of chemical bonds. The continual development and improvement of individual components of PEC systems is critical toward increasing the solar to fuel efficiency of prototype devices. Within this context, we describe a study on the growth of wurtzite indium phosphide (InP) nanowire (NW) arrays on silicon substrates and their subsequent implementation as light-absorbing photocathodes in PEC cells. The high onset potential (0.6 V vs the reversible hydrogen electrode) and photocurrent (18 mA/cm(2)) of the InP photocathodes render them as promising building blocks for high performance PEC cells. As a proof of concept for overall system integration, InP photocathodes were combined with a nanoporous bismuth vanadate (BiVO4) photoanode to generate an unassisted solar water splitting efficiency of 0.5%. PMID:27124203

  3. High pressure study of the zinc phosphide semiconductor compound in two different phases

    NASA Astrophysics Data System (ADS)

    Mokhtari, Ali

    2009-07-01

    Electronic and structural properties of the zinc phosphide semiconductor compound are calculated at hydrostatic pressure using the full-potential all-electron linearized augmented plane wave plus local orbital (FP-LAPW+lo) method in both cubic and tetragonal phases. The exchange-correlation potential is treated by the generalized gradient approximation within the scheme of Perdew, Burke and Ernzerhof, GGA96 (1996 Phys. Rev. Lett. 77 3865). Also, the Engel and Vosko GGA formalism, EV-GGA (Engel and Vosko 1993 Phys. Rev. B 47 13164), is used to improve the band-gap results. Internal parameters are optimized by relaxing the atomic positions in the force directions using the Hellman-Feynman approach. The lattice constants, internal parameters, bulk modulus, cohesive energy and band structures have been calculated and compared to the available experimental and theoretical results. The structural calculations predict that the stable phase is tetragonal. The effects of hydrostatic pressure on the behavior of band parameters such as band-gap, valence bandwidths and internal gaps (the energy gap between different parts of the valence bands) are studied using both GGA96 and EV-GGA.

  4. Electronic Structures of Free-Standing Nanowires made from Indirect Bandgap Semiconductor Gallium Phosphide.

    PubMed

    Liao, Gaohua; Luo, Ning; Chen, Ke-Qiu; Xu, H Q

    2016-01-01

    We present a theoretical study of the electronic structures of freestanding nanowires made from gallium phosphide (GaP)-a III-V semiconductor with an indirect bulk bandgap. We consider [001]-oriented GaP nanowires with square and rectangular cross sections, and [111]-oriented GaP nanowires with hexagonal cross sections. Based on tight binding models, both the band structures and wave functions of the nanowires are calculated. For the [001]-oriented GaP nanowires, the bands show anti-crossing structures, while the bands of the [111]-oriented nanowires display crossing structures. Two minima are observed in the conduction bands, while the maximum of the valence bands is always at the Γ-point. Using double group theory, we analyze the symmetry properties of the lowest conduction band states and highest valence band states of GaP nanowires with different sizes and directions. The band state wave functions of the lowest conduction bands and the highest valence bands of the nanowires are evaluated by spatial probability distributions. For practical use, we fit the confinement energies of the electrons and holes in the nanowires to obtain an empirical formula. PMID:27307081

  5. Osmium isotope variations in the oceans recorded by Fe-Mn crusts

    USGS Publications Warehouse

    Burton, K.W.; Bourdon, B.; Birck, J.-L.; Allegre, C.J.; Hein, J.R.

    1999-01-01

    This study presents osmium (Os) isotope data for recent growth surfaces of hydrogenetic ferromanganese (Fe-Mn) crusts from the Pacific, Atlantic and Indian Oceans. In general, these data indicate a relatively uniform Os isotopic composition for modern seawater, but suggest that North Atlantic seawater is slightly more radiogenic than that of the Pacific and Indian Oceans. The systematic difference in the Os isotopic composition between the major oceans probably reflects a greater input of old continental material with a high Re/Os ratio in the North Atlantic Ocean, consistent with the distribution of Nd and Pb isotopes. This spatial variation in the Os isotope composition in seawater is consistent with a residence time for Os of between 2 and 60 kyr. Indian Ocean samples show no evidence of a local source of radiogenic Os, which suggests that the present-day riverine input from the Himalaya-Tibet region is not a major source for Os. Recently formed Fe-Mn crusts from the TAG hydrothermal field in the North Atlantic yield an Os isotopic composition close to that of modern seawater, which indicates that, in this area, the input of unradiogenic Os from the hydrothermal alteration of oceanic crust is small. However, some samples from the deep Pacific (???4 km) possess a remarkably unradiogenic Os isotope composition (187Os/186Os ratios as low as 4.3). The compositional control of Os incorporation into the crusts and mixing relationships suggest that this unradiogenic composition is most likely due to the direct incorporation of micrometeoritic or abyssal peridotite particles, rather than indicating the presence of an unradiogenic deep-water mass. Moreover, this unradiogenic signal appears to be temporary, and local, and has had little apparent effect on the overall evolution of seawater. These results confirm that input of continental material through erosion is the dominant source of Os in seawater, but it is not clear whether global Os variations are due to the input

  6. Osmium isotope and highly siderophile element systematics of the lunar crust

    USGS Publications Warehouse

    Day, J.M.D.; Walker, R.J.; James, O.B.; Puchtel, I.S.

    2010-01-01

    Coupled 187Os/188Os and highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, and Re) abundance data are reported for pristine lunar crustal rocks 60025, 62255, 65315 (ferroan anorthosites, FAN) and 76535, 78235, 77215 and a norite clast in 15455 (magnesian-suite rocks, MGS). Osmium isotopes permit more refined discrimination than previously possible of samples that have been contaminated by meteoritic additions and the new results show that some rocks, previously identified as pristine, contain meteorite-derived HSE. Low HSE abundances in FAN and MGS rocks are consistent with derivation from a strongly HSE-depleted lunar mantle. At the time of formation, the lunar floatation crust, represented by FAN, had 1.4 ?? 0.3 pg g- 1 Os, 1.5 ?? 0.6 pg g- 1 Ir, 6.8 ?? 2.7 pg g- 1 Ru, 16 ?? 15 pg g- 1 Pt, 33 ?? 30 pg g- 1 Pd and 0.29 ?? 0.10 pg g- 1 Re (??? 0.00002 ?? CI) and Re/Os ratios that were modestly elevated (187Re/188Os = 0.6 to 1.7) relative to CI chondrites. MGS samples are, on average, characterised by more elevated HSE abundances (??? 0.00007 ?? CI) compared with FAN. This either reflects contrasting mantle-source HSE characteristics of FAN and MGS rocks, or different mantle-crust HSE fractionation behaviour during production of these lithologies. Previous studies of lunar impact-melt rocks have identified possible elevated Ru and Pd in lunar crustal target rocks. The new results provide no supporting evidence for such enrichments. If maximum estimates for HSE in the lunar mantle are compared with FAN and MGS averages, crust-mantle concentration ratios (D-values) must be ??? 0.3. Such D-values are broadly similar to those estimated for partitioning between the terrestrial crust and upper mantle, with the notable exception of Re. Given the presumably completely different mode of origin for the primary lunar floatation crust and tertiary terrestrial continental crust, the potential similarities in crust-mantle HSE partitioning for the Earth and Moon are somewhat

  7. First Measurements of Osmium Concentration and Isotopic Composition in a Summit, Greenland Ice Core

    NASA Astrophysics Data System (ADS)

    Osterberg, E. C.; Sharma, M.; Hawley, R. L.; Courville, Z.

    2010-12-01

    Osmium (Os) is one of the rarer elements in the environment and therefore one of the most difficult to accurately measure, but its isotopically distinctive crustal, mantle-derived, and extra-terrestrial sources make it a valuable geochemical tracer. Recent state-of-the-art analyses of precipitation, river water, and ocean water samples from around the world have revealed elevated concentrations of Os with a characteristically low (unradiogenic) Os isotopic signature (187Os/188Os). This unusual low Os isotopic signal has been interpreted as evidence for widespread Os pollution due to the smelting of Platinum Group Element (PGE) sulfide ores for use in automobile catalytic converters. However, an environmental time series of Os concentrations and isotopic composition spanning the pre-industrial to modern era has not previously been developed to evaluate changes in atmospheric Os sources through time. Here we present the first measurements of Os concentration and isotopic composition (to our knowledge) in a 100 m-long ice core collected from Summit, Greenland, spanning from ca. 1700 to 2010 AD. Due to the extremely low Os concentrations in snow (10-15 g/g), these analyses have only recently become possible with advances in Thermal Ionization Mass Spectrometry (TIMS) and ultra-clean analytical procedures. Initial results indicate that the 187Os/188Os of Greenland snow was unradiogenic (187Os/188Os = 0.13-0.15) for at least several periods over the past 300 years, including both pre-anthropogenic and modern times. Os concentrations in the Summit ice core are relatively high (11-52 pg/kg) compared to previously measured precipitation in North America, Europe, Asia and Antarctic sea ice (0.35-23 pg/kg). The low (unradiogenic) isotopic composition are consistent with extraterrestrial (cosmic dust and meteorites; 187Os/188Os = 0.13) and possibly volcanic (187Os/188Os = 0.15-0.6) Os sources, although the Os isotopic composition of volcanic emissions is poorly constrained

  8. A comparative field trial, conducted without pre-treatment census baiting, of the rodenticides zinc phosphide, thallium sulphate and gophacide against Rattus norvegicus.

    PubMed Central

    Rennison, B. D.

    1976-01-01

    The effectiveness of the single-dose poison treatments of farm rat infestations, analysed by comparing the weights of the post-treatment census bait takes in covariance with the weights of the prebait takes, showed that treatments with 2-5% zinc phosphide, 0-3% thallium sulphate or 0-3% gophacide were equally effective and significantly better than were treatments with 1% zinc phosphide or 0-1% thallium sulphate. The methodology and sensitivity of different analyses are also considered. PMID:1068192

  9. ROLE OF C AND P SITES ON THE CHEMICAL ACTIVITY OF METAL CARBIDE AND PHOSPHIDES: FROM CLUSTERS TO SINGLE-CRYSTAL SURFACES

    SciTech Connect

    RODRIGUEZ,J.A.; VINES, F.; LIU, P.; ILLAS, F.

    2007-07-01

    Transition metal carbides and phosphides have shown tremendous potential as highly active catalysts. At a microscopic level, it is not well understood how these new catalysts work. Their high activity is usually attributed to ligand or/and ensemble effects. Here, we review recent studies that examine the chemical activity of metal carbide and phosphides as a function of size, from clusters to extended surfaces, and metal/carbon or metal/phosphorous ratio. These studies reveal that the C and P sites in these compounds cannot be considered as simple spectators. They moderate the reactivity of the metal centers and provide bonding sites for adsorbates.

  10. Diffusion length variation in 0.5- and 3-MeV-proton-irradiated, heteroepitaxial indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Jain, Raj K.; Weinberg, Irving; Flood, Dennis J.

    1993-01-01

    Indium phosphide (InP) solar cells are more radiation resistant than gallium arsenide (GaAs) and silicon (Si) solar cells, and their growth by heteroepitaxy offers additional advantages leading to the development of light weight, mechanically strong, and cost-effective cells. Changes in heteroepitaxial InP cell efficiency under 0.5- and 3-MeV proton irradiations have been explained by the variation in the minority-carrier diffusion length. The base diffusion length versus proton fluence was calculated by simulating the cell performance. The diffusion length damage coefficient, K(sub L), was also plotted as a function of proton fluence.

  11. Antimalarial activity of ruthenium(II) and osmium(II) arene complexes with mono- and bidentate chloroquine analogue ligands.

    PubMed

    Ekengard, Erik; Glans, Lotta; Cassells, Irwin; Fogeron, Thibault; Govender, Preshendren; Stringer, Tameryn; Chellan, Prinessa; Lisensky, George C; Hersh, William H; Doverbratt, Isa; Lidin, Sven; de Kock, Carmen; Smith, Peter J; Smith, Gregory S; Nordlander, Ebbe

    2015-11-28

    Eight new ruthenium and five new osmium p-cymene half-sandwich complexes have been synthesized, characterized and evaluated for antimalarial activity. All complexes contain ligands that are based on a 4-chloroquinoline framework related to the antimalarial drug chloroquine. Ligands HL(1-8) are salicylaldimine derivatives, where HL(1) = N-(2-((2-hydroxyphenyl)methylimino)ethyl)-7-chloroquinolin-4-amine, and HL(2-8) contain non-hydrogen substituents in the 3-position of the salicylaldimine ring, viz. F, Cl, Br, I, NO2, OMe and (t)Bu for HL(2-8), respectively. Ligand HL(9) is also a salicylaldimine-containing ligand with substitutions in both 3- and 5-positions of the salicylaldimine moiety, i.e. N-(2-((2-hydroxy-3,5-di-tert-butylphenyl)methyl-imino)ethyl)-7-chloroquinolin-4-amine, while HL(10) is N-(2-((1-methyl-1H-imidazol-2-yl)methylamino)ethyl)-7-chloroquinolin-4-amine) The half sandwich metal complexes that have been investigated are [Ru(η(6)-cym)(L(1-8))Cl] (Ru-1-Ru-8, cym = p-cymene), [Os(η(6)-cym)(L(1-3,5,7))Cl] (Os-1-Os-3, Os-5, and Os-7), [M(η(6)-cym)(HL(9))Cl2] (M = Ru, Ru-HL(9); M = Os, Os-HL(9)) and [M(η(6)-cym)(L(10))Cl]Cl (M = Ru, Ru-10; M = Os, Os-10). In complexes Ru-1-Ru-8 and Ru-10, Os-1-Os-3, Os-5 and Os-7 and Os-10, the ligands were found to coordinate as bidentate N,O- and N,N-chelates, while in complexes Ru-HL(9) and Os-HL(9), monodentate coordination of the ligands through the quinoline nitrogen was established. The antimalarial activity of the new ligands and complexes was evaluated against chloroquine sensitive (NF54 and D10) and chloroquine resistant (Dd2) Plasmodium falciparum malaria parasite strains. Coordination of ruthenium and osmium arene moieties to the ligands resulted in lower antiplasmodial activities relative to the free ligands, but the resistance index is better for the ruthenium complexes compared to chloroquine. Overall, osmium complexes appeared to be less active than the corresponding ruthenium complexes. PMID:26491831

  12. Ternary Phosphide Ho 2Cu 6- xP 5- y, Its Crystal Structure, and REm+ n(Cu 2P 3) m(Cu 4P 2) n Relationship with Other Rhombohedral Rare-Earth Copper Phosphides

    NASA Astrophysics Data System (ADS)

    Mozharivskyj, Yurij; Kuz'ma, Yurij B.

    2000-04-01

    Crystals of the phosphide Ho2Cu6-xP5-y (x=0.41, y=0.50) have been prepared by annealing pressed powders of the elements at 800°C for 2 weeks. The structure was determined by single-crystal methods: space group Roverline3m (No. 166), Z=3, a=3.976(1) Å, c=40.554(8) Å, R=0.045 for 243 independent reflections [F>4σ(F)]. The unit cell of Ho2Cu6-xP5-y can be built from a close packing of Ho atoms and fragments of Cu3P, with one of the fragments containing additional P atoms. It can be also considered as an intercalation of additional P atoms in the YbCu3-xP2 structure (P. Klüfers, A. Mewis, and H. U. Schuster, Z. Kristallogr. 149, 211 (1979)). The REm+n(Cu2P3)m(Cu4P2)n relationship with other rare-earth copper phosphides, having similar structural characteristics is discussed.

  13. CVD growth and properties of boron phosphide on 3C-SiC

    NASA Astrophysics Data System (ADS)

    Padavala, Balabalaji; Frye, C. D.; Wang, Xuejing; Raghothamachar, Balaji; Edgar, J. H.

    2016-09-01

    Improving the crystalline quality of boron phosphide (BP) is essential for realizing its full potential in semiconductor device applications. In this study, 3C-SiC was tested as a substrate for BP epitaxy. BP films were grown on 3C-SiC(100)/Si, 3C-SiC(111)/Si, and 3C-SiC(111)/4H-SiC(0001) substrates in a horizontal chemical vapor deposition (CVD) system. Films were produced with good crystalline orientation and morphological features in the temperature range of 1000-1200 °C using a PH3+B2H6+H2 mixture. Rotational twinning was absent in the BP due to the crystal symmetry-matching with 3C-SiC. Confocal 3D Raman imaging of BP films revealed primarily uniform peak shift and peak widths across the scanned area, except at defects on the surface. Synchrotron white beam X-ray topography showed the epitaxial relationship between BP and 3C-SiC was (100) < 011 > BP||(100) < 011 > 3C-SiC and (111) < 11 2 ̅ > BP||(111) < 11 2 ̅ > 3C-SiC. Scanning electron microscopy, Raman spectroscopy and X-ray diffraction analysis indicated residual tensile strain in the films and improved crystalline quality at temperatures below 1200 °C. These results indicated that BP properties could be further enhanced by employing high quality bulk 3C-SiC or 3C-SiC epilayers on 4H-SiC substrates.

  14. Elevated Carboxyhaemoglobin Concentrations by Pulse CO-Oximetry is Associated with Severe Aluminium Phosphide Poisoning.

    PubMed

    Mashayekhian, Mohammad; Hassanian-Moghaddam, Hossein; Rahimi, Mitra; Zamani, Nasim; Aghabiklooei, Abbas; Shadnia, Shahin

    2016-09-01

    In pulse CO-oximetry of aluminium phosphide (ALP)-poisoned patients, we discovered that carboxyhaemoglobin (CO-Hb) level was elevated. We aimed to determine whether a higher CO level was detected in patients with severe ALP poisoning and if this could be used as a prognostic factor in these patients. In a prospective case-control study, 96 suspected cases of ALP poisoning were evaluated. In the ALP-poisoned group, demographic characteristics, gastric and exhalation silver nitrate test results, average CO-Hb saturation, methaemoglobin saturation, and blood pressure and blood gas analysis until death/discharge were recorded. Severely poisoned patients were defined as those with systolic blood pressure ≤80 mmHg, pH ≤7.2, or HCO3 ≤15 meq/L or those who died, while patients with minor poisoning were those without any of these signs/symptoms. A control group (37 patients) was taken from other medically ill patients to detect probable effects of hypotension and metabolic acidosis on CO-Hb and methaemoglobin saturations. Of 96 patients, 27 died and 37 fulfilled the criteria for severe poisoning. All patients with carbon monoxide saturation >18% met the criteria to be included in the severe poisoning group and all with a SpCO >25% died. Concerning all significant variables in univariate analysis of severe ALP toxicity, the only significant variable which could independently predict death was carbon monoxide saturation. Due to high mortality rate and need for intensive care support, early prediction of outcome is vital for choosing an appropriate setting (ICU or ordinary ward). CO-oximetry is a good diagnostic and prognostic factor in patients with ALP poisoning even before any clinical evidence of toxicity will develop. PMID:26899262

  15. A numerical simulation study of gallium-phosphide/silicon heterojunction passivated emitter and rear solar cells

    SciTech Connect

    Wagner, Hannes; Ohrdes, Tobias; Dastgheib-Shirazi, Amir; Puthen-Veettil, Binesh; König, Dirk; Altermatt, Pietro P.

    2014-01-28

    The performance of passivated emitter and rear (PERC) solar cells made of p-type Si wafers is often limited by recombination in the phosphorus-doped emitter. To overcome this limitation, a realistic PERC solar cell is simulated, whereby the conventional phosphorus-doped emitter is replaced by a thin, crystalline gallium phosphide (GaP) layer. The resulting GaP/Si PERC cell is compared to Si PERC cells, which have (i) a standard POCl{sub 3} diffused emitter, (ii) a solid-state diffused emitter, or (iii) a high efficiency ion-implanted emitter. The maximum efficiencies for these realistic PERC cells are between 20.5% and 21.2% for the phosphorus-doped emitters (i)–(iii), and up to 21.6% for the GaP emitter. The major advantage of this GaP hetero-emitter is a significantly reduced recombination loss, resulting in a higher V{sub oc}. This is so because the high valence band offset between GaP and Si acts as a nearly ideal minority carrier blocker. This effect is comparable to amorphous Si. However, the GaP layer can be contacted with metal fingers like crystalline Si, so no conductive oxide is necessary. Compared to the conventional PERC structure, the GaP/Si PERC cell requires a lower Si base doping density, which reduces the impact of the boron-oxygen complexes. Despite the lower base doping, fewer rear local contacts are necessary. This is so because the GaP emitter shows reduced recombination, leading to a higher minority electron density in the base and, in turn, to a higher base conductivity.

  16. Effect of acute aluminum phosphide exposure on rats: a biochemical and histological correlation.

    PubMed

    Anand, R; Kumari, Priyanka; Kaushal, Alka; Bal, Amanjit; Wani, Willayat Y; Sunkaria, Aditya; Dua, Raina; Singh, Surjit; Bhalla, Ashish; Gill, Kiran Dip

    2012-11-23

    Aluminum phosphide (AlP), a widely used fumigant and rodenticide leads to high mortality if ingested. Its toxicity is due to phosphine liberated when it comes in contact with moisture. The exact mechanism of action of phosphine is not known. In this study male Wistar rats were used. The animals received a single dose (20mg AlP/kg body weight i.g.) orally. Basic serum biochemical parameters, activity of mitochondrial complexes, antioxidant enzymes and parameters of oxidative stress, individual mitochondrial cytochrome levels were measured along with tissue histopathology and immunostaining for cytochrome c and compared with controls. The serum levels of creatinine kinase-MB, lactate dehydrogenase, magnesium and cortisol were higher (p<0.01); the activities of mitochondrial complexes I, II, IV were observed to be significantly decreased in liver tissue in treated rats (p<0.01). The activity of catalase was lower (p<0.05) with a significant increase in lipid peroxidation (p<0.05) whereas superoxide dismutase and glutathione peroxidase were unaffected in them. There was a significant decrease in all the cytochromes in brain and liver tissues (p<0.05) with the exception of cytochrome b in brain, the levels of which remained same. Histopathology revealed congestion in most organs with centrizonal hemorrhagic necrosis in liver. Ultra structural changes indicating mitochondrial injury was observed in heart, liver and kidney tissues. There was also a marked reduction in the cytochrome-c immunostaining compared to the controls. Toxicity due to AlP appears to result as a consequence of both-energy insufficiency and oxidative stress, with a possible and preferential interaction with the tissue cytochromes. PMID:23041170

  17. Hydroxyethyl Starch Could Save a Patient With Acute Aluminum Phosphide Poisoning.

    PubMed

    Marashi, Sayed Mahdi; Nasri Nasrabadi, Zeynab; Jafarzadeh, Mostafa; Mohammadi, Sogand

    2016-07-01

    A 40-year-old male patient with suicidal ingestion of one tablet of aluminium phosphide was referred to the department of toxicology emergency of Baharloo Hospital, Tehran, Iran. The garlic odor was smelled from the patient and abdominal pain and continuous vomiting as well as agitation and heartburn were the first signs and symptoms. Systolic and diastolic blood pressures at the arrival time were 95 and 67 mmHg, respectively. Gastric lavage with potassium permanganate (1:10,000), and 2 vials of sodium bicarbonate through a nasogastric tube was started for the patient and the management was continued with free intravenous infusion of 1 liter of NaCl 0.9% serum plus NaHCO3, hydrocortisone acetate (200 mg), calcium gluconate (1 g) and magnesium sulfate (1 g). Regarding the large intravenous fluid therapy and vasoconstrictor administering (norepinephrine started by 5 µg/min and continued till 15 µg/min), there were no signs of response and the systolic blood pressure was 49 mmHg. At this time, hydroxyethyl starch (HES) (6% hetastarch 600/0.75 in 0.9% sodium chloride) with a dose of 600 cc in 6 hours was started for the patient. At the end of therapy with HES, the patient was stable with systolic and diastolic blood pressure of 110 and 77 mmHg, respectively. He was discharged on the 6th day after the psychological consultation, with normal clinical and paraclinical examinations. This is the first report of using HES in the management of AlP poisoning and its benefit to survive the patient. PMID:27424021

  18. Search for a meteoritic component in impact-melt rocks from the Lonar crater, India - Evidence from osmium isotope systematics

    NASA Astrophysics Data System (ADS)

    Schulz, T.; Luguet, A.; Koeberl, C.

    2013-12-01

    Introduction: The Lonar crater in western India (Maharashtra) is a bowl-shaped simple impact structure of 1830 m diameter and a depth of 120 m below the rim crest. The crater formed 0.656 × 0.081 Ma ago on the 65 Ma old basaltic lava flows of the Deccan Traps (Jourdan et al. 2010) and is one of the few terrestrial impact structures to have formed in basaltic host-rocks. In the absence of actual meteorite fragments, the impact origin of this structure was supported by the identification of a variety of shock metamorphic features (e.g. Fredriksson et al. 1973). However, clear indications of an extraterrestrial component in impactites based on geochemical studies are absent or remained ambiguous so far (e.g. Osae et al. 2005). As the Os isotope tool has the potential to provide firm constraints on the presence or absence of even very small (<<1%) contributions of meteoritic matter to impactite lithologies (e.g. Koeberl et al. 2002), we conduct a detailed Os isotope study of a variety of unshocked host-basalts (target rocks) and impactites (impact-melt rocks) from the Lonar crater. Samples and Method: All samples analyzed in this study were collected in 2000 and 2001 and were geochemically characterized by Osae et al. (2005). Osmium (and additional PGE) analyses were performed on about 2 g whole rock powders, which were spiked with a mixed 190Os,185Re,191Ir,194Pt tracer, and digested via high pressure Asher using inverse aqua regia. Osmium solvent extraction and microdistillation were performed as described by Cohen and Waters (1996). Osmium isotopic compositions were measured using a TRITON N-TIMS at the Department of Lithospheric Research in Vienna. Results and Discussion: Osmium data on seven target and nine impact melt rocks reveal 187Os/188Os ratios ranging from ~0.38 to ~2.23 for the target rocks and from ~0.22 to ~0.59 for the nine analyzed impact melt rocks, whereas Os concentrations range from ~7.1 to ~31.6 ppt and ~7.2 to ~134 ppt, respectively. Although in

  19. Proto-Pacific OAE2 osmium isotope records revealed: global correlation and basin dynamics

    NASA Astrophysics Data System (ADS)

    Du Vivier, A.; Selby, D. S.; Takashima, R.; Condon, D. J.; Nishi, H.

    2013-12-01

    Globally the marine realm across the Cenomanian-Turonian boundary interval records the oceanic anoxic event (OAE) 2. This event has been studied using several geochemical proxies at several sites from the proto-Atlantic. In contrast, there are limited studies from the proto-Pacific. We present initial osmium isotope stratigraphy (Osi) from two proto-Pacific sites: the Yezo Group (YG) section, Hokkaido, Japan, and the Great Valley Sequence (GVS), California, USA; to evaluate the Os seawater chemistry of the proto-Pacific with that of the proto-Atlantic. For the YG section the Osi prior to OAE2 are moderately radiogenic and heterogeneous. Synchronous with OAE2 onset the Osi abruptly become unradiogenic and remain homogenous before showing a gradual return to more radiogenic Osi throughout the middle to late OAE2. The Osi profile from the YG is analogous to the record from the Portland #1 core of the Western Interior Seaway (WIS). In contrast, the Osi profile from the GVS is disparate to the YG profile and those of several proto-Atlantic locations. The Osi for the GVS oscillate from radiogenic to unradiogenic values across the OAE2. We suggest the Osi of the GVS was influenced interchangeably by both unradiogenic and radiogenic Os; where radiogenic Osi is associated with weathered evolved continental rocks and unradiogenic Osi is derived from a submarine hydrothermal input associated with the Caribbean Large Igneous Province (CLIP). All proto-Atlantic sections show a synchronous correlation between Osi and δ13Corg excursions. However, this is not the case for the YG. As such we infer that the OAE2 excursion has been misidentified in the δ13Cwood analysis for the YG and thus the onset is ~24 m higher in the section. In order to further facilitate correlation we identified a number of zircon bearing tuff horizons throughout the YG for U-Pb ID-TIMS zircon geochronology. The Osi data and U-Pb age(s) combined, improves the correlation and the identification of the OAE2

  20. Electronic structures of ruthenium and osmium complexes of 9,10-phenanthrenequinone.

    PubMed

    Biswas, Manas Kumar; Patra, Sarat Chandra; Maity, Amarendra Nath; Ke, Shyue-Chu; Adhikary, Nirmal Das; Ghosh, Prasanta

    2012-06-18

    The reaction of 9,10-phenanthrenequinone (PQ) with [M(II)(H)(CO)(X)(PPh(3))(3)] in boiling toluene leads to the homolytic cleavage of the M(II)-H bond, affording the paramagnetic trans-[M(PQ)(PPh(3))(2)(CO)X] (M = Ru, X = Cl, 1; M = Os, X = Br, 3) and cis-[M(PQ)(PPh(3))(2)(CO)X] (M = Ru, X = Cl, 2; M = Os, X = Br, 4) complexes. Single-crystal X-ray structure determinations of 1, 2·toluene, and 4·CH(2)Cl(2), EPR spectra, and density functional theory (DFT) calculations have substantiated that 1-4 are 9,10-phenanthrenesemiquinone radical (PQ(•-)) complexes of ruthenium(II) and osmium(II) and are defined as trans-[Ru(II)(PQ(•-))(PPh(3))(2)(CO)Cl] (1), cis-[Ru(II)(PQ(•-))(PPh(3))(2)(CO)Cl] (2), trans-[Os(II)(PQ(•-))(PPh(3))(2)(CO) Br] (3), and cis-[Os(II)(PQ(•-))(PPh(3))(2)(CO)Br] (4). Two comparatively longer C-O [average lengths: 1, 1.291(3) Å; 2·toluene, 1.281(5) Å; 4·CH(2)Cl(2), 1.300(8) Å] and shorter C-C lengths [1, 1.418(5) Å; 2·toluene, 1.439(6) Å; 4·CH(2)Cl(2), 1.434(9) Å] of the OO chelates are consistent with the presence of a reduced PQ(•-) ligand in 1-4. A minor contribution of the alternate resonance form, trans- or cis-[M(I)(PQ)(PPh(3))(2)(CO)X], of 1-4 has been predicted by the anisotropic X- and Q-band electron paramagnetic resonance spectra of the frozen glasses of the complexes at 25 K and unrestricted DFT calculations on 1, trans-[Ru(PQ)(PMe(3))(2)(CO)Cl] (5), cis-[Ru(PQ)(PMe(3))(2)(CO)Cl] (6), and cis-[Os(PQ)(PMe(3))(2)(CO)Br] (7). However, no thermodynamic equilibria between [M(II)(PQ(•-))(PPh(3))(2)(CO)X] and [M(I)(PQ)(PPh(3))(2)(CO)X] tautomers have been detected. 1-4 undergo one-electron oxidation at -0.06, -0.05, 0.03, and -0.03 V versus a ferrocenium/ferrocene, Fc(+)/Fc, couple because of the formation of PQ complexes as trans-[Ru(II)(PQ)(PPh(3))(2)(CO)Cl](+) (1(+)), cis-[Ru(II)(PQ)(PPh(3))(2)(CO)Cl](+) (2(+)), trans-[Os(II)(PQ)(PPh(3))(2)(CO)Br](+) (3(+)), and cis-[Os(II)(PQ)(PPh(3))(2)(CO)Br](+) (4(+)). The trans

  1. Marine osmium isotopic record of cherts across the Triassic-Jurassic boundary: implications for environmental change

    NASA Astrophysics Data System (ADS)

    Suzuki, K.; Kuroda, J.; Hori, R. S.; Ohkouchi, N.; Grocke, D. R.

    2010-12-01

    Attention has long been focused on relationships between massive volcanisms and major environmental change such as large mass extinctions (e.g., Wignall, 2001). The Triassic-Jurassic (T-J) boundary at c.a. 200 Ma has been regarded as one of the five biggest mass extinction events in the Phanerozoic when a substantial proportion of marine and terrestrial species became extinct. This period also marks extensive magmatic activities associated with the emplacement of the Central Atlantic Magmatic Province (CAMP). These magmatic activities are likely to be a possible forcing mechanism for the climatic changes in the T-J transition. However, the mechanism triggering the T-J mass extinction is still under debate, because there are remarkable difficulties in correlating the timing of the widespread CAMP volcanic activity with the environmental events, and in estimating the environmental impact of large-scale igneous activity. Since seawater Os isotopic composition varies in response to change in balance of Os supply from continental, mantle and extraterrestrial sources, Os isotopic record from hydrogenous fraction of marine sediments is useful to reconstruct secular changes in the relative contribution from these sources (Ravizza and Peucker-Ehrenbrink, 2003; Tugeon and Creaser, 2008; Tejada et al., 2009). Such information possibly provides us important constraints on the mechanism of the environmental change and mass extinction. Although Cohen and Coe (2007) have reported Os isotopic records across the T-J boundary from southern England, no data have been reported from the Paleo-Pacific (Panthalassa) pelagic basin that covered approximately half of the Earth’s surface. Here we present a high-resolution isotopic record of osmium extracted from bedded chert successions across the T-J boundary in Kurusu section, central Japan, deposited on a Panthalassa deep basin. Our new dataset show a gradual decrease in seawater 187Os/188Os values through the Rhaetian and subsequent

  2. Osmium Isotopic Composition of the K/T Boundary Sediments from Sumbar: A Progress Report

    NASA Astrophysics Data System (ADS)

    Meisel, T.; Krahenbuhl, U.; Nazarov, M. A.

    1993-07-01

    Osmium isotope measurements have been performed on the boundary clay at different Cretaceous-Tertiary boundary (KTB) sites [1-5] since [6] suggested that Os isotopes are an indicator of an extraterrestrial component. The debate over "impact vs. volcanic" could not be resolved, but an isotope ratio close to chondritic could be demonstrated. The study of the distribution of iridium in the stratigraphy of the KTB cannot distinguish the contribution of chondritic and/or terrestrial Ir respectively, whereas the Os isotopes allow us to better constrain a mixing model. The ^187Os/^186Os ratio of the continental crust and chondritic reservoirs differ by at least 10-30 times. Assuming certain parameters, we should be able to calculate the proportion of the reservoirs making up the sediments of the KTB section. We studied a complete section of the KTB of Sumbar, Turkmenistan [7], for its Os isotopic composition. In the section 0-30 cm above the boundary clay, the ^187Os/^186Os ratio increases from 1.15 to 1.47, whereas the Ir concentration decreases from 66 to 1.4 ng/g or 66 to 4.7 ng/g on a carbonate-free basis respectively. Calculations show that the chondritic component makes up 9% at the boundary layer and decreases down to 0.6% at +30 cm. The data cannot be simply explained by varying admixtures of a chondritic component to a sediment of constant Os concentration and isotopic signature. To explain the Os ratios completely it is necessary to consider a mixture of four components (extraterrestrial, ejecta material, local terrigeneous, and carbonacous sediments) with certain assumptions: (1) The extraterrestrial source is chondritic in its Os and Re content and has an initial Os isotope ratio of 1.12 at 65 Ma (time of impact), which is above the average for normal chondrites but is within the range measured so far (e.g., Murray). (2) The ejecta material has a higher Os concentration (0.2 ng/g) than the sediments and is only present in the first 5 cm of the sequence above

  3. Electrocatalytic and photocatalytic hydrogen production from acidic and neutral-pH aqueous solutions using iron phosphide nanoparticles.

    PubMed

    Callejas, Juan F; McEnaney, Joshua M; Read, Carlos G; Crompton, J Chance; Biacchi, Adam J; Popczun, Eric J; Gordon, Thomas R; Lewis, Nathan S; Schaak, Raymond E

    2014-11-25

    Nanostructured transition-metal phosphides have recently emerged as Earth-abundant alternatives to platinum for catalyzing the hydrogen-evolution reaction (HER), which is central to several clean energy technologies because it produces molecular hydrogen through the electrochemical reduction of water. Iron-based catalysts are very attractive targets because iron is the most abundant and least expensive transition metal. We report herein that iron phosphide (FeP), synthesized as nanoparticles having a uniform, hollow morphology, exhibits among the highest HER activities reported to date in both acidic and neutral-pH aqueous solutions. As an electrocatalyst operating at a current density of -10 mA cm(-2), FeP nanoparticles deposited at a mass loading of ∼1 mg cm(-2) on Ti substrates exhibited overpotentials of -50 mV in 0.50 M H2SO4 and -102 mV in 1.0 M phosphate buffered saline. The FeP nanoparticles supported sustained hydrogen production with essentially quantitative faradaic yields for extended time periods under galvanostatic control. Under UV illumination in both acidic and neutral-pH solutions, FeP nanoparticles deposited on TiO2 produced H2 at rates and amounts that begin to approach those of Pt/TiO2. FeP therefore is a highly Earth-abundant material for efficiently facilitating the HER both electrocatalytically and photocatalytically. PMID:25250976

  4. Exploiting the Brønsted Acidity of Phosphinecarboxamides for the Synthesis of New Phosphides and Phosphines

    PubMed Central

    Jupp, Andrew R; Trott, Gemma; Payen de la Garanderie, Éléonore; Holl, James D G; Carmichael, Duncan; Goicoechea, Jose M

    2015-01-01

    We demonstrate that the synthesis of new N-functionalized phosphinecarboxamides is possible by reaction of primary and secondary amines with PCO− in the presence of a proton source. These reactions proceed with varying degrees of success, and although primary amines generally afford the corresponding phosphinecarboxamides in good yields, secondary amines react more sluggishly and often give rise to significant decomposition of the 2-phosphaethynolate precursor. Of the new N-derivatized phosphinecarboxamides available, PH2C(O)NHCy (Cy=cyclohexyl) can be obtained in sufficiently high yields to allow for the exploration of its Brønsted acidity. Thus, deprotonating PH2C(O)NHCy with one equivalent of potassium bis(trimethylsilyl)amide (KHMDS) gave the new phosphide [PHC(O)NHCy]−. In contrast, deprotonation with half of an equivalent gives rise to [P{C(O)NHCy}2]− and PH3. These phosphides can be employed to give new phosphines by reactions with electrophiles, thus demonstrating their enormous potential as chemical building blocks. PMID:25892576

  5. Electrical Wiring of the Aldehyde Oxidoreductase PaoABC with a Polymer Containing Osmium Redox Centers: Biosensors for Benzaldehyde and GABA

    PubMed Central

    Badalyan, Artavazd; Dierich, Marlen; Stiba, Konstanze; Schwuchow, Viola; Leimkühler, Silke; Wollenberger, Ulla

    2014-01-01

    Biosensors for the detection of benzaldehyde and γ−aminobutyric acid (GABA) are reported using aldehyde oxidoreductase PaoABC from Escherichia coli immobilized in a polymer containing bound low potential osmium redox complexes. The electrically connected enzyme already electrooxidizes benzaldehyde at potentials below −0.15 V (vs. Ag|AgCl, 1 M KCl). The pH-dependence of benzaldehyde oxidation can be strongly influenced by the ionic strength. The effect is similar with the soluble osmium redox complex and therefore indicates a clear electrostatic effect on the bioelectrocatalytic efficiency of PaoABC in the osmium containing redox polymer. At lower ionic strength, the pH-optimum is high and can be switched to low pH-values at high ionic strength. This offers biosensing at high and low pH-values. A “reagentless” biosensor has been formed with enzyme wired onto a screen-printed electrode in a flow cell device. The response time to addition of benzaldehyde is 30 s, and the measuring range is between 10–150 µM and the detection limit of 5 µM (signal to noise ratio 3:1) of benzaldehyde. The relative standard deviation in a series (n = 13) for 200 µM benzaldehyde is 1.9%. For the biosensor, a response to succinic semialdehyde was also identified. Based on this response and the ability to work at high pH a biosensor for GABA is proposed by coimmobilizing GABA-aminotransferase (GABA-T) and PaoABC in the osmium containing redox polymer. PMID:25587431

  6. Rhenium and osmium isotopes in black shales and Ni-Mo-PGE-rich sulfide layers, Yukon Territory, Canada, and Hunan and Guizhou provinces, China

    USGS Publications Warehouse

    Horan, M.F.; Morgan, J.W.; Grauch, R.I.; Coveney, R.M., Jr.; Murowchick, J.B.; Hulbert, L.J.

    1994-01-01

    Rhenium and osmium abundances and osmium isotopic compositions were determined by negative thermal ionization mass spectrometry for samples of Devonian black shale and an associated Ni-enriched sulfide layer from the Yukon Territory, Canada. The same composition information was also obtained for samples of early Cambrian Ni-Mo-rich sulfide layers hosted in black shale in Guizhou and Hunan provinces, China. This study was undertaken to constrain the origin of the PGE enrichment in the sulfide layers. Samples of the Ni sulfide layer from the Yukon Territory are highly enriched in Re, Os, and other PGE, with distinctly higher Re/192Os but similar Pt/Re, compared to the black shale host. Re-Os isotopic data of the black shale and the sulfide layer are approximately isochronous, and the data plot close to reference isochrons which bracket the depositional age of the enclosing shales. Samples of the Chinese sulfide layers are also highly enriched in Re, Os, and the other PGE. Re/192Os are lower than in the Yukon sulfide layer. Re-Os isotopic data for the sulfide layers lie near a reference isochron with an age of 560 Ma, similar to the depositional age of the black shale host. The osmium isotopic data suggest that Re and PGE enrichment of the brecciated sulfide layers in both the Yukon Territory and in southern China may have occurred near the time of sediment deposition or during early diagenesis, during the middle to late Devonian and early Cambrian, respectively. ?? 1994.

  7. Photocatalytic performance of nitrogen, osmium co-doped TiO2 for removal of eosin yellow in water under simulated solar radiation.

    PubMed

    Kuvarega, Alex T; Krause, Rui W M; Mamba, Bhekie B

    2013-07-01

    Nitrogen, osmium co-doped TiO2 photocatalysts were prepared by a modified sol-gel method using ammonia as the nitrogen source and osmium tetroxide as the source of osmium. The role of rutile phase OsO2 in enhancing the photocatalytic activity of rutile TiO2 towards the degradation of Eosin Yellow was investigated. The materials were characterised by various techniques that include FTIR, Raman, XRD, SEM, EDS, TEM, TGA and DRUV-Vis. The amorphous, oven dried sample was transformed to the anatase and then the rutile phase with increasing calcination temperature. DRUV-Vis analysis revealed a red shift in absorption with increasing calcination temperature, confirmed by a decrease in the band gap of the material. The photocatalytic activity of N, Os co-doped TiO2 was evaluated using eosin yellow degradation and activity increased with increase in calcination temperature under simulated solar irradiation. The rutile phase of the co-doped TiO2 was found to be more effective in degrading the dye (k(a) = 1.84 x 10(-2) min(-1)) compared to the anatase co-doped phase (k(a) = 9.90 x 10(-3) min(-1)). The enhanced photocatalytic activity was ascribed to the synergistic effects of rutile TiO2 and rutile OsO2 in the N, Os co-doped TiO2. PMID:23901525

  8. Ab initio study of high-pressure behavior of a low compressibility metal and a hard material: Osmium and diamond

    NASA Astrophysics Data System (ADS)

    Hebbache, M.; Zemzemi, M.

    2004-12-01

    We performed Density-Functional electronic structure calculations in order to investigate the high pressure behavior of Os beyond what is tractable experimentally with a diamond-anvil cell. In addition to the room-temperature and pressure structure hcp, two hypothetical structures of Os have been considered: fcc and ω (hexagonal phase with three atoms by unit cell). Phase transitions are suggested by these calculations. For calculating the bulk modulus, the reciprocal of the compressibility, of Os and that of diamond, the computed total energies vs volume curves were fit to three different equations of state. Several volume ranges have been considered during the fitting procedure. First, it is shown that the claim of Cynn and co-workers [Phys. Rev. Lett. 88, 135701 (2002)] is confirmed at weak compression. Osmium is less compressible than diamond which is known as the hardest and the least compressible material. However, with increasing pressure osmium becomes more compressible than diamond. At strong compression, osmium transforms to the ω phase. It is also shown that the reconstructive phase transition hcp→fcc could be induced by cooling in this low compressibility material.

  9. Toxicology and carcinogenesis studies of indium phosphide (CAS No. 22398-90-7) in F344/N rats and B6C3F1 mice (inhalation studies).

    PubMed

    2001-07-01

    Indium phosphide is used to make semiconductors,injection lasers, solar cells, photodiodes, and light-emittingdiodes. Indium phosphide was nominated for study because of its widespread use in the microelectronics industry, the potential for worker exposure,and the absence of chronic toxicity data. Male and female F344/N rats and B6C3F1 mice were exposed to indium phosphide (greater than 99% pure) by inhalation for 14 weeks or 2 years. The frequency of micronuclei was determined in the peripheral blood of mice exposed to indium phosphide for 14 weeks. 14-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were exposed to particulate aerosols of indium phosphide with amass median aerodynamic diameter of approximately 1.2 microm at concentrations of 0, 1, 3, 10, 30, or 100 mg/m3 by inhalation, 6 hours per day, 5 days per week (weeks 1 through 4 and weeks 10 through 14) or 7 days per week (weeks 5 through 9) to accommodate a concurrent teratology study. One male in the 100 mg/m3 group died before the end of the study. Body weight gains of all males and females exposed to 100 mg/m3 were less than those of the chamber controls. As a result of indium phosphide exposure, the lungs of all exposed rats had a gray to black discoloration and were significantly enlarged, weighing 2.7- to 4.4-fold more than those of the chamber controls. Indium phosphide particles were observed throughout the respiratory tract and in the lung-associated lymph nodes. A spectrum of inflammatory and proliferative lesions generally occurred in the lungs of all exposed groups of rats and consisted of alveolar proteinosis, chronic inflammation, interstitial fibrosis, and alveolar epithelial hyperplasia. Pulmonary inflammation was attended by increased leukocyte and neutrophil counts in the blood. The alveolar proteinosis was the principal apparent reason for the increase in lung weights. Indium phosphide caused inflammation at the base of the epiglottis of the larynx and hyperplasia of the

  10. Mössbauer Spectroscopy Investigation and Hydrodesulfurization Properties of Iron–nickel Phosphide Catalysts

    SciTech Connect

    Gaudette, Amy F.; Burns, Autumn W.; Hayes, John R.; Smith, Mica C.; Bowker, Richard H.; Seda, Takele; Bussell, Mark E.

    2010-05-25

    Unsupported and silica-supported FexNi2-xPy catalysts having a range of metal compositions (0 < x 6 2.0) were investigated using Mössbauer spectroscopy, and the results correlated with the surface and hydrodesulfurization (HDS) properties of the supported catalysts. Mössbauer spectroscopy permits determination of the relative site occupancy of Fe atoms in tetrahedral (M(1)) and pyramidal (M(2)) sites in the FexNi2-xPy materials. Fe atoms preferentially occupy M(2) sites for materials with significant Fe contents (x > ~0.60), but the Fe site preference reverses as the Fe content decreases (x < ~0.60). Similar occupation trends are observed for the unsupported and silica-supported FexNi2-xPy materials. Thiophene HDS measurements of the FexNi2-xPy/SiO2 catalysts revealed catalysts with high Fe contents (0.80 6 x 6 2.00) to have low activities, while the activities of Ni-rich catalysts increased dramatically with increased Ni content (0.03 6 x 6 0.60). The highest HDS activity was measured for a catalyst having a nominal precursor composition of Fe0.03Ni1.97P2.00/SiO2; this catalyst was 40% more active than a optimized nickel phosphide catalyst prepared from a precursor having a nominal composition of Ni2.00P1.60/SiO2. The 25 wt.% Fe0.03Ni1.97P2.00/SiO2 catalyst also had a dibenzothiophene HDS activity just over 10% higher than that of the 25 wt.% Ni2.00P1.60/SiO2 catalyst at 548 K. The trend of increasing HDS activity for the FexNi2-xPy/ SiO2 catalysts correlates with preferential Fe occupation of M(1) sites (and, therefore, Ni occupation of M(2) sites). Supported by X-ray photoelectron spectroscopy and oxygen chemisorption measurements, we conclude that the high activity of Ni-rich FexNi2-xPy/SiO2 catalysts can be traced to a high surface density of Ni in M(2) sites that are resistant to site blockage due to S incorporation.

  11. Sniffing for Clues to the Dinosaurs Demise: Measurement of Osmium Isotope Compositions and Platinum Group Element Abundances in Volcanic Emissions

    NASA Astrophysics Data System (ADS)

    Sims, K. W.; Peucker-Ehrenbrink, B.; Mather, T.; Pyle, D.; Martin, R.; Gauthier, P.; Aiuppa, A.

    2005-12-01

    Platinum Group Elements (PGE: Os, Ir, Rh, Ru, Pt, Pd) and osmium isotopes measured in marine and terrestrial sediment, snow and ice records are important paleo-tracers of riverine, hydrothermal, extraterrestrial, volcanic and anthropogenic inputs into the global surficial environment. For instance, the marine Os isotope record across the Cretaceous-Tertiary Boundary (KTB) indicates that the onset of the main phase of Deccan volcanism and the transient late Maastrichtian warming preceded the large extraterrestrial impact and the related KTB mass extinction by several hundred thousand years [Ravizza and Peucker-Ehrenbrink, 2003]. Distinguishing extraterrestrial from volcanic PGE sources has been difficult due to the similarity in Os isotopic compositions, complex PGE fractionations, and our lack of knowledge of the Os isotopic composition and PGE abundances in volcanic aerosols. These difficulties have fueled vigorous debate about extraterrestrial vs. volcanic triggers of mass extinctions in the geologic record. To assess the volcanic contribution to the global Re-Os-PGE cycle we have initiated a study of Os isotopic compositions and PGE abundances in volcanic emissions from volcanoes around the globe. Here we report preliminary data on PGE abundances and Os isotopes measured in gas and aerosol filter samples from Vulcan Masaya, Nicaragua and Mt Etna, Italy. Samples were analyzed by ID-ICPMS (ThermoFinnigan ELEMENT 2 and NEPTUNE) at the Woods Hole Oceanographic Institution. Osmium isotope compositions of the filters are unradiogenic (0.1272 to 0.187). Osmium concentrations range from 28 to 97 pg/cubic meter and are 3-4 orders of magnitude lower than those measured by Krahenbuhl et al. [1992] during the spring 1984 eruption of Mauna Loa just after the lava fountaining phase. Normalized PGE abundance patterns are fractionated relative to carbonaceous chondrites and two important features distinguish the pattern from other important PGE sources: 1) Os/Ir is much higher

  12. Synthesis and x-ray characterization of cobalt phosphide (Co₂P) nanorods for the oxygen reduction reaction

    SciTech Connect

    Doan-Nguyen, Vicky V.T.; Su, Dong; Zhang, Sen; Trigg, Edward B.; Agarwal, Rahul; Li, Jing; Winey, Karen I.; Murray, Christopher B.

    2015-07-14

    Low temperature fuel cells are clean, effective alternative fuel conversion technology. Oxygen reduction reaction (ORR) at the fuel cell cathode has required Pt as the electrocatalyst for high activity and selectivity of the four-electron reaction pathway. Targeting a less expensive, earth abundant alternative, we have developed the synthesis of cobalt phosphide (Co₂P) nanorods for ORR. Characterization techniques that include total X-ray scattering and extended X-ray absorption fine structure revealed a deviation of the nanorods from bulk crystal structure with a contraction along the b orthorhombic lattice parameter. The carbon supported nanorods have comparable activity but are remarkably more stable than conventional Pt catalysts for the oxygen reduction reaction in alkaline environments.

  13. Synthesis and x-ray characterization of cobalt phosphide (Co₂P) nanorods for the oxygen reduction reaction

    DOE PAGESBeta

    Doan-Nguyen, Vicky V.T.; Su, Dong; Zhang, Sen; Trigg, Edward B.; Agarwal, Rahul; Li, Jing; Winey, Karen I.; Murray, Christopher B.

    2015-07-14

    Low temperature fuel cells are clean, effective alternative fuel conversion technology. Oxygen reduction reaction (ORR) at the fuel cell cathode has required Pt as the electrocatalyst for high activity and selectivity of the four-electron reaction pathway. Targeting a less expensive, earth abundant alternative, we have developed the synthesis of cobalt phosphide (Co₂P) nanorods for ORR. Characterization techniques that include total X-ray scattering and extended X-ray absorption fine structure revealed a deviation of the nanorods from bulk crystal structure with a contraction along the b orthorhombic lattice parameter. The carbon supported nanorods have comparable activity but are remarkably more stable thanmore » conventional Pt catalysts for the oxygen reduction reaction in alkaline environments.« less

  14. Simulation of high-efficiency n[sup +]p indium phosphide solar cell results and future improvements

    SciTech Connect

    Jain, R.K.; Flood, D.J. )

    1994-12-01

    A simulation of the highest efficiency (19.1% AM0) n[sup +]p indium phosphide (InP) solar cell was made using a computer code PC-1D in order to understand it and suggest future improvements to it. Available cell design and process data was used in the simulation. Minority carrier diffusion lengths in the emitter and base have been varied to match the experimental cell I-V characteristics with the calculated results. To further understand and improve the InP cell efficiency, simulations were performed using improved values of cell material and process parameters. The authors show that the efficiency of this cell could be increased to more than 23% AM0 by incorporating the suggested cell material, design and process improvements. At these high efficiencies InP cell technology will be very attractive for space use.

  15. Chemical nature of silicon nitride-indium phosphide interface and rapid thermal annealing for InP MISFETs

    NASA Technical Reports Server (NTRS)

    Biedenbender, M. D.; Kapoor, V. J.

    1990-01-01

    A rapid thermal annealing (RTA) process in pure N2 or pure H2 was developed for ion-implanted and encapsulated indium phosphide compound semiconductors, and the chemical nature at the silicon nitride-InP interface before and after RTA was examined using XPS. Results obtained from SIMS on the atomic concentration profiles of the implanted silicon in InP before and after RTA are presented, together with electrical characteristics of the annealed implants. Using the RTA process developed, InP metal-insulator semiconductor FETs (MISFETS) were fabricated. The MISFETS prepared had threshold voltages of +1 V, transconductance of 27 mS/mm, peak channel mobility of 1200 sq cm/V per sec, and drain current drift of only 7 percent.

  16. Characterization of the Absolute Crystal Polarity across Twin Boundaries in Gallium Phosphide Using Convergent-Beam Electron Diffraction.

    PubMed

    Cohen; McKernan; Carter

    1999-05-01

    : The measurement of absolute crystal polarity is crucial to understanding the structural properties of many planar defects in compound semiconductors. Grain boundaries, including twin boundaries, in the sphalerite lattice are uniquely characterized by the crystallographic misorientation of individual grains and the direction of the crystal polarity in domains adjoining the grain boundary. To evaluate crystal polarity in gallium phosphide (GaP), asymmetrical interference contrast in convergent-beam electron-diffraction (CBED) patterns was used to ascertain the nature and direction of polar bonds. The direction of the asymmetry in the electron diffraction reflections was correlated with the crystal polarity of a sample with known polarity. The CBED technique was applied to determine the polar orientation of grains adjoining Sigma = 3 coherent and lateral twin boundaries in polycrystalline GaP. PMID:10383990

  17. Probing hydrodesulfurization over bimetallic phosphides using monodisperse Ni2-xMxP nanoparticles encapsulated in mesoporous silica

    NASA Astrophysics Data System (ADS)

    Danforth, Samuel J.; Liyanage, D. Ruchira; Hitihami-Mudiyanselage, Asha; Ilic, Boris; Brock, Stephanie L.; Bussell, Mark E.

    2016-06-01

    Metal phosphide nanoparticles encapsulated in mesoporous silica provide a well-defined system for probing the fundamental chemistry of the hydrodesulfurization (HDS) reaction over this new class of hydrotreating catalysts. To investigate composition effects in bimetallic phosphides, the HDS of dibenzothiophene (DBT) was carried out over a series of Ni-rich Ni2-xMxP@mSiO2 (M = Co, Fe) nanocatalysts (x ≤ 0.50). The Ni2-xMxP nanoparticles (average diameters: 11-13 nm) were prepared by solution-phase arrested precipitation and encapsulated in mesoporous silica, characterized by a range of techniques (XRD, TEM, IR spectroscopy, BET surface area, CO chemisorption) and tested for DBT HDS activity and selectivity. The highest activity was observed for a Ni1.92Co0.08P@mSiO2 nanocatalyst, but the overall trend was a decrease in HDS activity with increasing Co or Fe content. In contrast, the highest turnover frequency (TOF) was observed for the most Co- and Fe-rich compositions based on sites titrated by CO chemisorption. IR spectral studies of adsorbed CO on the Ni2-xMxP@mSiO2 catalysts indicate that an increase in electron density occurs on Ni sites as the Co or Fe content is increased, which may be responsible for the increased TOFs of the catalytic sites. The Ni2-xMxP@mSiO2 nanocatalysts exhibit a strong preference for the direct desulfurization pathway (DDS) for DBT HDS that changes only slightly with increasing Co or Fe content.

  18. Tracking millennial-scale Holocene glacial advance and retreat using Osmium isotopes: Insights from the Greenland Ice Sheet

    NASA Astrophysics Data System (ADS)

    Rooney, Alan; Selby, David; Lloyd, Jeremy; Roberts, David; Lückge, Andreas; Sageman, Bradley; Prouty, Nancy

    2016-04-01

    Using new high-resolution osmium (Os) isotope stratigraphy from cores adjacent to the Greenland ice sheet we highlight the potential for chemostratigraphy to contribute to our understanding of ice sheet dynamics. This study utilizes sediment cores that have excellent chronological controls and demonstrates the role of local and regional weathering fluxes on the marine Os residence time. Distal to the Greenland ice streams core MSM-520 displays a steady lowering of the Os isotope composition during the Holocene. In contrast, proximal to the calving front of Jakobshavn Isbræ (core DA00-06), the Os isotope stratigraphy highlights four stages of ice stream retreat and advance. Our chemostratigraphic records provide vital benchmarks as we attempt to better constrain the future response of major ice sheets to climate change. Variations in Os isotope composition from sediment and macro-algae (seaweed) sourced from both near-field and far-field settings emphasize the overwhelming effect local weathering sources have on seawater Os isotope composition.

  19. Fiber-optic infrared reflectance spectroelectrochemical studies of osmium and ruthenium nitrosyl porphyrins containing alkoxide and thiolate ligands.

    PubMed

    Carter, Shawn M; Lee, Jonghyuk; Hixson, Christopher Adam; Powell, Douglas R; Wheeler, Ralph A; Shaw, Michael J; Richter-Addo, George B

    2006-03-14

    We have examined the redox behavior of the osmium and ruthenium compounds (OEP)M(NO)(OEt) and (OEP)M(NO)(SEt) (OEP = octaethylporphyrinato dianion; M = Os, Ru) by cyclic voltammetry and infrared spectroelectrochemistry. The compound (OEP)Os(NO)(OEt) undergoes a single reversible oxidation process in dichloromethane. In contrast, the thiolate compound (OEP)Os(NO)(SEt) undergoes a net irreversible oxidation resulting in formal loss of the SEt ligand. Extended Hückel calculations on crystal structures of these two compounds provide insight into the nature of their HOMOs. In the case of the alkoxide compound, the HOMO is largely metal centered, with 70% of the charge located in the metal's orbital and approximately 25% on the porphyrin ring. However, the HOMO of the thiolate compound consists of a pi bonding interaction between the metal dxz orbital and the px orbital on the sulfur, and a pi antibonding interaction between the metal d orbital and a pi* orbital on NO. The redox behavior of the Ru analogues have been determined, and are compared with those of the Os compounds. PMID:16505913

  20. Electrochemical proton-coupled electron transfer of an osmium aquo complex: theoretical analysis of asymmetric tafel plots and transfer coefficients.

    PubMed

    Ludlow, Michelle K; Soudackov, Alexander V; Hammes-Schiffer, Sharon

    2010-02-01

    Electrochemical proton-coupled electron transfer of an osmium aquo complex attached to a self-assembled monolayer on a gold electrode is studied with a recently developed theoretical formulation. The calculated hydrogen/deuterium kinetic isotope effect for the standard rate constant, the cathodic transfer coefficient at zero overpotential, and the Tafel plot are in excellent agreement with experimental data. The input quantities to the heterogeneous rate constant expressions were calculated with density functional theory in conjunction with dielectric continuum models, and no parameters were fit to experimental data. The theoretical calculations indicate that the asymmetry of the Tafel plot and the deviation of the transfer coefficient at zero overpotential from the standard value of one-half arise from the change in the equilibrium proton donor-acceptor distance upon electron transfer. The direction of the asymmetry and deviation from one-half is determined by the sign of this distance change, and the magnitude of these effects is determined by the magnitude of this distance change, as well as the reorganization energy and the distance dependence of the overlap between the initial and final proton vibrational wave functions. This theory provides experimentally testable predictions for the impact of specific system properties on the qualitative behavior of the Tafel plots. PMID:20067257

  1. Osmium isotope ratios of PGM grains associated with the Freetown Layered Complex, Sierra Leone, and their origin

    NASA Astrophysics Data System (ADS)

    Hattori, Keiko; Cabri, Louis J.; Hart, Stanley R.

    1991-03-01

    Osmium isotope ratios for two types of platinum group mineral (PGM) nuggets of eluvial (residual) origin, associated with the Freetown Layered Gabbro Complex, were determined in-situ using an ion microprobe. The values for erlichmanite nuggets are ≈1.08. Those for PGM inclusions in Pt-Fe alloy nuggets are higher, ranging from 1.2 to 2.1. Ratios of187Os/186Os vary between the nuggets, but they are consistent within individual nuggest. The data suggest early formation of the erlichmanite nuggets, prior to a postulated substantial contribution of crustal Os. The Pt-Fe alloy nuggets, on the other hand, were formed later in a residual melt which was contaminated by crustal Os due to the assimilation (<10%) or the gaseous/fluid transport of Os from Archaean host rocks into the magma. The lack of systematic mineralogical and chemical changes of the Complex and extensive granulitization in the adjacent host rocks and xenoliths may favor the latter process. The lack of high187Os/186Os ratios, consistent187Os/186Os values within individual nuggets and their textures and mineralogy suggest that the studied PGM nuggets were not formed during lateritization or in low-temperature depositional environments.

  2. Topotactic Conversion of Copper(I) Phosphide Nanowires for Sensitive Electrochemical Detection of H2O2 Release from Living Cells.

    PubMed

    Li, Zhenzhen; Xin, Yanmei; Wu, Wenlong; Fu, Baihe; Zhang, Zhonghai

    2016-08-01

    In this work, we clearly demonstrate for the first time the use of transition-metal phosphides to set up a new cathodic analysis platform for sensitive and selective electrochemical nonenzymatic detection of H2O2. With the help of a facile topotactic conversion method, the noble metal-free electrocatalyst of copper(I) phosphide nanowires on three-dimensional porous copper foam (Cu3P NWs/CF) is fabricated with electrochemical anodized Cu(OH)2 NWs as precursor. The Cu3P NWs/CF-based sensor presents excellent electrocatalytic activity for H2O2 reduction with a detection limit of 2 nM, the lowest detection limit achieved by noble-metal free electrocatalyst, which guarantees the possibility of sensitive and reliable detection of H2O2 release from living tumorigenic cells, thus showing the potential application as a sensitive cancer cell detection probe. PMID:27377605

  3. Cluster-like molybdenum phosphide anchored on reduced graphene oxide for efficient hydrogen evolution over a broad pH range.

    PubMed

    Yan, Haijing; Jiao, Yanqing; Wu, Aiping; Tian, Chungui; Zhang, Xiaomeng; Wang, Lei; Ren, Zhiyu; Fu, Honggang

    2016-07-21

    Cluster-like molybdenum phosphide particles were anchored on reduced graphene oxide (MoP/rGO) with high uniformity by using phosphomolybdic acid as a molybdenum precursor based on a robust assembly-immobilization method. Benefiting from the small size, and even distribution of the MoP particles, the MoP/rGO hybrid exhibits superior electrocatalytic activity towards the hydrogen evolution reaction both in acidic and alkaline media. PMID:27380736

  4. Aqueous corrosion of phosphide minerals from iron meteorites: a highly reactive source of prebiotic phosphorus on the surface of the early Earth.

    PubMed

    Pasek, Matthew A; Lauretta, Dante S

    2005-08-01

    We present the results of an experimental study of aqueous corrosion of Fe-phosphide under conditions relevant to the early Earth. The results strongly suggest that iron meteorites were an important source of reactive phosphorus (P), a requirement for the formation of P-based life. We further demonstrate that iron meteorites were an abundant source of phosphide minerals early in Earth history. Phosphide corrosion was studied in five different solutions: deionized water, deionized water buffered with sodium bicarbonate, deionized water with dissolved magnesium and calcium chlorides, deionized water containing ethanol and acetic acid, and deionized water containing the chlorides, ethanol, and acetic acid. Experiments were performed in the presence of both air and pure Ar gas to evaluate the effect of atmospheric chemistry. Phosphide corrosion in deionized water results in a metastable mixture of mixed-valence, P-bearing ions including pyrophosphate and triphosphate, key components for metabolism in modern life. In a pH-buffered solution of NaHCO(3), the condensed and reduced species diphosphonate is an abundant corrosion product. Corrosion in ethanol- and acetic acid-containing solutions yields additional P-bearing organic molecules, including acetyl phosphonate and a cyclic triphosphorus molecule. Phosphonate is a major corrosion product of all experiments and is the only P-bearing molecule that persists in solutions with high concentrations of magnesium and calcium chlorides, which suggests that phosphonate may have been a primitive oceanic source of P. The stability and reactivity of phosphonate and hypophosphite in solution were investigated to elucidate reaction mechanisms and the role of mineral catalysts on P-solution chemistry. Phosphonate oxidation is rapid in the presence of Fe metal but negligible in the presence of magnetite and in the control sample. The rate of hypophosphite oxidation is independent of reaction substrate. PMID:16078869

  5. Aqueous Corrosion of Phosphide Minerals from Iron Meteorites: A Highly Reactive Source of Prebiotic Phosphorus on the Surface of the Early Earth

    NASA Astrophysics Data System (ADS)

    Pasek, Matthew A.; Lauretta, Dante S.

    2005-08-01

    We present the results of an experimental study of aqueous corrosion of Fe-phosphide under conditions relevant to the early Earth. The results strongly suggest that iron meteorites were an important source of reactive phosphorus (P), a requirement for the formation of P-based life. We further demonstrate that iron meteorites were an abundant source of phosphide minerals early in Earth history. Phosphide corrosion was studied in five different solutions: deionized water, deionized water buffered with sodium bicarbonate, deionized water with dissolved magnesium and calcium chlorides, deionized water containing ethanol and acetic acid, and deionized water containing the chlorides, ethanol, and acetic acid. Experiments were performed in the presence of both air and pure Ar gas to evaluate the effect of atmospheric chemistry. Phosphide corrosion in deionized water results in a metastable mixture of mixed-valence, P-bearing ions including pyrophosphate and triphosphate, key components for metabolism in modern life. In a pH-buffered solution of NaHCO3, the condensed and reduced species diphosphonate is an abundant corrosion product. Corrosion in ethanol- and acetic acid-containing solutions yields additional P-bearing organic molecules, including acetyl phosphonate and a cyclic triphosphorus molecule. Phosphonate is a major corrosion product of all experiments and is the only P-bearing molecule that persists in solutions with high concentrations of magnesium and calcium chlorides, which suggests that phosphonate may have been a primitive oceanic source of P. The stability and reactivity of phosphonate and hypophosphite in solution were investigated to elucidate reaction mechanisms and the role of mineral catalysts on P-solution chemistry. Phosphonate oxidation is rapid in the presence of Fe metal but negligible in the presence of magnetite and in the control sample. The rate of hypophosphite oxidation is independent of reaction substrate.

  6. X-Ray Emission Spectra and Electronic Structures of Red Phosphorus, 3d Transition-Metal Phosphides and III V Compounds

    NASA Astrophysics Data System (ADS)

    Sugiura, Chikara

    1995-07-01

    The P Kβ emission spectra in fluorescence from red amorphous phosphorus, 3d transition-metal phosphides TiP, CrP, FeP, Fe2P, Fe3P, CoP, Co2P, Ni5P4, Ni2P, Ni3P, Cu3P, ZnP2 (black) and Zn3P2, and the semiconducting phosphides of the III-V type, BP, AlP, GaP and InP are measured with a high-resolution two-crystal vacuum spectrometer equipped with Ge(111) crystals. The influence of the metal atoms appears distinctly on the P Kβ fluorescence emission spectra. The measured spectra are compared with available X-ray emission and XPS valence-band spectra and theoretical energy-band calculations on a common energy scale. It is shown that considerable p-d, s mixing occurs in the valence bands of the 3d transition-metal phosphides and the P 3p states mix fairly with the P 3s states in the valence bands of red phosphorus, Gap and InP

  7. Ionic liquids as a convenient new medium for the catalytic asymmetric dihydroxylation of olefins using a recoverable and reusable osmium/ligand.

    PubMed

    Branco, Luís C; Afonso, Carlos A M

    2004-06-25

    The use of room-temperature ionic liquids (RTILs) in the Sharpless catalytic asymmetric dihydroxylation (AD) as a cosolvent or replacement of the tert-butanol was studied in detail by screening 11 different RTILs. The AD reaction is faster in 1-n-butyl-3-methylimidazolium hexafluorophosphate [C(4)mim][PF(6)] as a cosolvent than in the conventional system of tert-butanol/H(2)O. For the range of six substrates tested, comparable or even higher yields and enantiomeric excess (ee) were found using [C(4)mim][PF(6)] or 1-n-octyl-3-methylimidazolium hexafluorophosphate [C(8)mim][PF(6)] compared to the conventional solvent system. Due to high affinity of the catalytic osmium/quiral ligand system to the ionic liquid, the use of ionic liquid/water (biphasic) or ionic liquid/water/tert-butanol (monophasic) solvent systems provides a recoverable, reusable, robust, efficient, and simple system for the AD reaction. Using 1-hexene and [C(4)mim][PF(6)] as RTIL it was possible to reuse the catalytic system for 9 cycles with only a 5% of yield reduction from the first cycle, allowing an overall yield of 87%, TON = 1566, and with similar ee. Additionally, for each cycle, after extraction of the reaction mixture with diethyl ether, the osmium content in the organic phase (containing the AD product) and in the aqueous phase was in the range of the detection limit (osmium content of the previous cycle. PMID:15202893

  8. Confirmation of a meteoritic component in impact-melt rocks of the Chesapeake Bay impact structure, Virginia, USA - Evidence from osmium isotopic and PGE systematics

    USGS Publications Warehouse

    Lee, S.R.; Horton, J.W., Jr.; Walker, R.J.

    2006-01-01

    The osmium isotope ratios and platinum-group element (PGE) concentrations of impact-melt rocks in the Chesapeake Bay impact structure were determined. The impact-melt rocks come from the cored part of a lower-crater section of suevitic crystalline-clast breccia in an 823 m scientific test hole over the central uplift at Cape Charles, Virginia. The 187Os/188Os ratios of impact-melt rocks range from 0.151 to 0.518. The rhenium and platinum-group element (PGE) concentrations of these rocks are 30-270?? higher than concentrations in basement gneiss, and together with the osmium isotopes indicate a substantial meteoritic component in some impact-melt rocks. Because the PGE abundances in the impact-melt rocks are dominated by the target materials, interelemental ratios of the impact-melt rocks are highly variable and nonchondritic. The chemical nature of the projectile for the Chesapeake Bay impact structure cannot be constrained at this time. Model mixing calculations between chondritic and crustal components suggest that most impact-melt rocks include a bulk meteoritic component of 0.01-0.1% by mass. Several impact-melt rocks with lowest initial 187Os/188Os ratios and the highest osmium concentrations could have been produced by additions of 0.1%-0.2% of a meteoritic component. In these samples, as much as 70% of the total Os may be of meteoritic origin. At the calculated proportions of a meteoritic component (0.01-0.1% by mass), no mixtures of the investigated target rocks and sediments can reproduce the observed PGE abundances of the impact-melt rocks, suggesting that other PGE enrichment processes operated along with the meteoritic contamination. Possible explanations are 1) participation of unsampled target materials with high PGE abundances in the impact-melt rocks, and 2) variable fractionations of PGE during syn- to post-impact events. ?? The Meteoritical Society, 2006.

  9. A new probe of solvent accessibility of bound photosensitizers. 1. Ruthenium(II) and osmium(II) photosensitizers in sodium lauryl sulfate micelles

    SciTech Connect

    Hauenstein, B.L. Jr.; Dressick, W.J.; Buell, S.L.; Demas, J.N.; DeGraff, B.A.

    1983-06-29

    A new method of measuring solvent accessibility of photosensitizers bound to organized media is presented. In particular, the solvent accessibility of a series of ruthenium(II) and osmium(II) photosensitizers bound to sodium lauryl sulfate micelles has been determined. The method takes advantage of the large solvent deuterium effect on the excited-state lifetimes of these complexes. The solvent accessibility of the bound complexes correlates with the hydrophobicity of the ligands. The potential application of this method to a variety of other systems is mentioned.

  10. Catalytic oxidation of alkanes by a (salen)osmium(VI) nitrido complex using H2O2 as the terminal oxidant.

    PubMed

    Chen, Man; Pan, Yi; Kwong, Hoi-Ki; Zeng, Raymond J; Lau, Kai-Chung; Lau, Tai-Chu

    2015-09-14

    The osmium(VI) nitrido complex, [Os(VI)(N)(L)(CH3OH)](+) (1, L = N,N'-bis(salicylidene)-o-cyclohexyldiamine dianion) is an efficient catalyst for the oxidation of alkanes under ambient conditions using H2O2 as the oxidant. Alkanes are oxidized to the corresponding alcohols and ketones, with yields up to 75% and turnover numbers up to 2230. Experimental and computational studies are consistent with a mechanism that involves O-atom transfer from H2O2 to [Os(VI)(N)(L)](+) to generate an [Os(VIII)(N)(O)(L)](+) active intermediate. PMID:26229990

  11. Osmium-isotope Evidence for a Projectile Component in Impact-melt Rocks, Chesapeake Bay Impact Structure, Virginia, USA

    NASA Astrophysics Data System (ADS)

    Lee, S.; Horton, J. W.; Walker, R. J.

    2004-12-01

    The late Eocene Chesapeake Bay impact structure (CBIS) is preserved beneath post-impact sediments on the Atlantic margin of Virginia. This 85-km-diameter complex crater formed on the continental shelf of a passive margin in a layered target consisting of ocean water, Cretaceous and Tertiary sediments (mainly siliciclastic), and crystalline basement rocks. The basement rocks include Neoproterozoic granitoids and felsite as well as gneiss of undetermined age. In May, 2004, the USGS drilled an 823-m test hole in the central uplift of the CBIS at Cape Charles, Va., providing drill cuttings and limited core. The core from 744 to 823 m depth contains crystalline-clast breccia and brecciated gneiss that are distinct from sediment-clast breccias recovered from coreholes in the annular trough of the CBIS. Rocks interpreted to be impact-melt clasts and dikes in the crystalline-clast breccia were sampled for analyses of osmium (Os) concentrations and 187Os/188Os ratios to test for evidence of the projectile. These analyses were conducted on samples from a dike (aphanitic to partly hyaline, ST2440.8C) within a gneissic block, from a block of holocrystalline mafic rock (aphanitic, ST2453.3C), and from a flow-laminated bomb (aphanitic to partly hyaline, ST2570.0C). The Os concentrations and 187Os/188Os ratios for samples ST2440.8C, ST2453.3C and ST2570.0C are 0.928, 0.711 and 0.312 ppb, and 0.15205, 0.15545 and 0.22345, respectively. These values are much higher (Os) or lower (187Os/188Os) than those reported for rocks of the upper continental crust, suggesting a significant contribution of osmium from the projectile in these impact-melt rocks. Moreover, a strong negative correlation between 187Os/188Os and Os for these samples suggests that it may be possible to use mixing curves to calculate the proportions of projectile and target-rock components. Our results from the CBIS contrast with those from the Chicxulub crater, where there is little or no evidence for the

  12. Osmium isotope perturbations during the Pliensbachian-Toarcian (Early Jurassic): Relationships between volcanism, weathering, and climate change

    NASA Astrophysics Data System (ADS)

    Percival, Lawrence; Cohen, Anthony; Davies, Marc; Dickson, Alexander; Jenkyns, Hugh; Hesselbo, Stephen; Mather, Tamsin; Xu, Weimu; Storm, Marisa

    2016-04-01

    The Mesozoic Era marked a time of greenhouse conditions on Earth, punctuated by a number of abrupt perturbations to the carbon cycle, such as Ocean Anoxic Events (OAEs). OAEs are typically marked in the stratigraphic record by the appearance of organic-rich shales, and excursions in carbon-isotope ratios registered in carbonates and organic matter. A range of geochemical evidence indicates changes to global temperatures, typically featuring abrupt warming possibly caused by CO2 emissions resulting from Large Igneous Province (LIP) volcanism. A warmer atmosphere is thought to have led to changes in the global hydrological cycle, which would likely have enhanced global weathering rates. The Toarcian OAE (T-OAE) is inferred, from osmium isotope ratios in organic-rich mudrocks from Yorkshire and western North America, to have been a time of such increased weathering rates. However, it is likely that the sediments at these locations were deposited in relatively hydrographically restricted environments, potentially more susceptible to the influence of local input; consequently, they may not offer the best representation of the global seawater Os-isotope composition at that time. In this study, we have measured the osmium isotope composition of siciliclastic mudrocks in a core from the Mochras borehole (Llanbedr Farm, Cardigan Bay Basin, Wales), which constitutes a sedimentary record for a fully open-marine seaway that connected Tethys to the Boreal ocean during the Toarcian. We analysed samples from strata including both the T-OAE and preceding Pliensbachian-Toarcian boundary (Pl-To), both of which record multiple geochemical excursions and records of elevated extinction amongst benthic fauna. We find that the latest Pliensbachian records seawater 187Os/188Os of ~0.35-0.4, rising to ~0.5 at the Pl-To boundary, before a further rise to ~0.7 during the T-OAE. We conclude that such increases in radiogenic Os flux to the ocean system resulted from enhanced continental

  13. Coronary artery wall imaging in mice using osmium tetroxide and micro-computed tomography (micro-CT)

    SciTech Connect

    Pai, Vinay M.; Kozlowski, Megan; Donahue, Danielle; Miller, Elishiah; Xiao, Xianghui; Chen, Marcus Y.; Yu, Zu-Xi; Connelly, Patricia; Jeffries, Kenneth; Wen, Han

    2012-05-10

    The high spatial resolution of micro-computed tomography (micro-CT) is ideal for 3D imaging of coronary arteries in intact mouse heart specimens. Previously, micro-CT of mouse heart specimens utilized intravascular contrast agents that hardened within the vessel lumen and allowed a vascular cast to be made. However, for mouse coronary artery disease models, it is highly desirable to image coronary artery walls and highlight plaques. For this purpose, we describe an ex vivo contrast-enhanced micro-CT imaging technique based on tissue staining with osmium tetroxide (OsO{sub 4}) solution. As a tissue-staining contrast agent, OsO{sub 4} is retained in the vessel wall and surrounding tissue during the fixation process and cleared from the vessel lumens. Its high X-ray attenuation makes the artery wall visible in CT. Additionally, since OsO{sub 4} preferentially binds to lipids, it highlights lipid deposition in the artery wall. We performed micro-CT of heart specimens of 5- to 25-week-old C57BL/6 wild-type mice and 5- to 13-week-old apolipoprotein E knockout (apoE{sup -/-}) mice at 10 {mu}m resolution. The results show that walls of coronary arteries as small as 45 {mu}m in diameter are visible using a table-top micro-CT scanner. Similar image clarity was achieved with 1/2000th the scan time using a synchrotron CT scanner. In 13-week-old apoE mice, lipid-rich plaques are visible in the aorta. Our study shows that the combination of OsO{sub 4} and micro-CT permits the visualization of the coronary artery wall in intact mouse hearts.

  14. Studies of high temperature ternary phases in mixed-metal-rich early transition metal sulfide and phosphide systems

    SciTech Connect

    Marking, G.A.

    1994-01-04

    Investigations of ternary mixed early transition metal-rich sulfide and phosphide systems resulted in the discovery of new structures and new phases. A new series of Zr and Hf - group V transition metal - sulfur K-phases was synthesized and crystallographically characterized. When the group V transition metal was Nb or Ta, the unit cell volume was larger than any previously reported K-phase. The presence of adventitious oxygen was determined in two K-phases through a combination of neutron scattering and X-ray diffraction experiments. A compound Hf{sub 10}Ta{sub 3}S{sub 3} was found to crystallize in a new-structure type similar to the known gamma brasses. This structure is unique in that it is the only reported {open_quotes}stuffed{close_quotes} gamma-brass type structure. The metal components, Hf and Ta, are larger in size and more electropositive than the metals found in normal gamma brasses (e.g. Cu and Zn) and because of the larger metallic radii, sulfur can be incorporated into the structure where it plays an integral role in stabilizing this phase relative to others. X-ray single-crystal, X-ray powder and neutron powder refinements were performed on this structure. A new structure was found in the ternary Nb-Zr-P system which has characteristics in common with many known early transition metal-rich sulfides, selenides, and phosphides. This structure has the simplest known interconnection of the basic building blocks known for this structural class. Anomalous scattering was a powerful tool for differentiating between Zr and Nb when using Mo K{alpha} X-radiation. The compounds ZrNbP and HfNbP formed in the space group Prima with the simple Co{sub 2}Si structure which is among the most common structures found for crystalline solid materials. Solid solution compounds in the Ta-Nb-P, Ta-Zr-P, Nb-Zr-P, Hf-Nb-P, and Hf-Zr-S systems were crystallographically characterized. The structural information corroborated ideas about bonding in metal-rich compounds.

  15. MRT letter: high resolution SEM imaging of nano-architecture of cured urea-formaldehyde resin using plasma coating of osmium.

    PubMed

    Park, Byung-Dae; Singh, Adya P; Nuryawan, Arif; Hwang, Kiju

    2013-11-01

    Nanoarchitecture of cured urea-formaldehyde (UF) resins was examined with a field-emission scanning electron microscope (FE-SEM) after coating samples with osmium, which is considered to produce particles of considerably smaller size compared to other metal coatings used in SEM studies. This method enabled comparison of the nanoarchitecture of UF resins of low (1.0) and high (1.6) formaldehyde/urea (F/U) mole ratios to be made, based on imaging of extremely small size particles as part of UF resin architecture, not described before. Imaging revealed presence of relatively large globular particles (148.084-703.983 nm size range) as well as smaller substructures (28.004-39.604 nm size range) as part of the architecture of 1.0-mole UF resin. Globular particles were also present in 1.6 mole UF resin, but of considerably smaller size (14.760-50.269 nm). The work presented demonstrates usefulness of osmium coating in unraveling the intricacies of the nanostructural organization of cured UF resins, prompting wider application of this immensely useful but grossly underutilized metal coating type in high resolution SEM examination of biological and materials samples. PMID:23922188

  16. Antiferromagnetic transitions of osmium-containing rare earth double perovskites Ba{sub 2}LnOsO{sub 6} (Ln=rare earths)

    SciTech Connect

    Hinatsu, Yukio Doi, Yoshihiro; Wakeshima, Makoto

    2013-10-15

    The perovskite-type compounds containing both rare earth and osmium Ba{sub 2}LnOsO{sub 6} (Ln=Pr, Nd, Sm–Lu) have been prepared. Powder X-ray diffraction measurements and Rietveld analysis show that Ln{sup 3+} and Os{sup 5+} ions are structurally ordered at the M site of the perovskite BaMO{sub 3}. Magnetic susceptibility and specific heat measurements show that an antiferromagnetic ordering of Os{sup 5+} ions has been observed for Ba{sub 2}LnOsO{sub 6} (Ln=Pr, Nd, Sm, Eu, Gd, Lu) at 65–71 K. Magnetic ordering of Ln{sup 3+} moments occurs when the temperature is furthermore decreased. - Graphical abstract: The perovskite-type compounds containing both rare earth and osmium Ba{sub 2}LnOsO{sub 6} (Ln=Pr, Nd, Sm–Lu) have been prepared. An antiferromagnetic ordering of Os{sup 5+} ions has been observed for Ba{sub 2}LnOsO{sub 6} (Ln=Pr, Nd, Sm, Eu, Gd, Lu) at 65–71 K. Measurements and analysis of the specific heat for Ba{sub 2}PrOsO{sub 6} show that magnetic ordering of the Pr{sup 3+} moments should have occurred at ∼20 K. Display Omitted.

  17. Luminescence response of an osmium(II) complex to macromolecular polyanions for the detection of heparin and chondroitin sulfate in biomedical preparations.

    PubMed

    Wu, Hao; Wu, Jain; Saez, Christopher; Campana, Maria; Megehee, Elise G; Wang, Enju

    2013-12-01

    Heparin, dextran sulfate (DS), chondroitin sulfate (CS), and carrageenan are found to enhance the luminescence intensity of an osmium(II) carbonyl complex with phenanthroline (phen) and 4-phenylpyridine (4-phpy) ligands in aqueous and ethanol solutions. The enhancing effect of the polyanions on the luminescence of the complex is heavily dependent on the sulfate content and other factors such as structure, solubility, and counter ions of the polyanion. The highly sulfated dextran and ι-carrageenan have the most profound effect, while the low charged κ-carrageenan and CS have the least response in aqueous solution. All polyanions exhibited enhanced luminescence intensity of the complex in ethanol solutions, and even the low charged CS and κ-carrageenan enhanced the luminescence more than 4 times. DS contamination of the sodium heparin at 5% can show a significant increase in luminescence response. The osmium complex is found to be highly successful in the fast and sensitive detection of heparin in commercial injectable samples with various backgrounds as well as the detection of CS in over the counter food supplement tablets. PMID:24267085

  18. Constraints on the genesis of gold mineralization at the Homestake Gold Deposit, Black Hills, South Dakota from rhenium-osmium sulfide geochronology

    NASA Astrophysics Data System (ADS)

    Morelli, Ryan M.; Bell, Chris C.; Creaser, Robert A.; Simonetti, Antonio

    2010-06-01

    The Homestake gold deposit, located in the Black Hills, South Dakota, USA, is one of the largest known hydrothermal gold deposits globally, with total mining production exceeding 40 Moz Au. Rhenium-osmium geochronology of ore-associated arsenopyrite and pyrrhotite was performed in an effort to delineate the timing of gold mineralization in relation to known tectonothermal events in the northern Black Hills. Arsenopyrite yields a rhenium-osmium (Re-Os) age of 1,736 ± 8 Ma (mean squared weighted deviation = 1.6), consistent with existing age constraints for gold mineralization, whereas Re-Os pyrrhotite data are highly scattered and do not yield a meaningful mineralization age. This is taken to indicate that the Re-Os arsenopyrite chronometer is robust to at least 400°C, whereas the Re-Os pyrrhotite chronometer is likely disturbed by temperatures of 300-350°C. The Re-Os arsenopyrite age and initial Os ratio (0.28 ± 0.15) are interpreted to indicate that gold was introduced at ca. 1,730 Ma, coincident with the onset of exhumation of crustal blocks and, possibly, the earliest intrusive phases of Harney Peak granite magmatism. New in situ U-Pb monazite analyses from an aplite dike in the east-central Black Hills indicate that granite magmatism was a protracted event, persisting until at least ca. 1,690 Ma.

  19. Chemical Reaction between Boric Acid and Phosphine Indicates Boric Acid as an Antidote for Aluminium Phosphide Poisoning

    PubMed Central

    Soltani, Motahareh; Shetab-Boushehri, Seyed F.; Shetab-Boushehri, Seyed V.

    2016-01-01

    Objectives: Aluminium phosphide (AlP) is a fumigant pesticide which protects stored grains from insects and rodents. When it comes into contact with moisture, AlP releases phosphine (PH3), a highly toxic gas. No efficient antidote has been found for AlP poisoning so far and most people who are poisoned do not survive. Boric acid is a Lewis acid with an empty p orbital which accepts electrons. This study aimed to investigate the neutralisation of PH3 gas with boric acid. Methods: This study was carried out at the Baharlou Hospital, Tehran University of Medical Sciences, Tehran, Iran, between December 2013 and February 2014. The volume of released gas, rate of gas evolution and changes in pH were measured during reactions of AlP tablets with water, acidified water, saturated boric acid solution, acidified saturated boric acid solution, activated charcoal and acidified activated charcoal. Infrared spectroscopy was used to study the resulting probable adduct between PH3 and boric acid. Results: Activated charcoal significantly reduced the volume of released gas (P <0.01). Although boric acid did not significantly reduce the volume of released gas, it significantly reduced the rate of gas evolution (P <0.01). A gaseous adduct was formed in the reaction between pure AlP and boric acid. Conclusion: These findings indicate that boric acid may be an efficient and non-toxic antidote for PH3 poisoning. PMID:27606109

  20. Aluminium phosphide-induced genetic and oxidative damages in vitro: Attenuation by Laurus nobilis L. leaf extract

    PubMed Central

    Türkez, Hasan; Toğar, Başak

    2013-01-01

    Objective: The present investigation was undertaken to assess the protective effect of Laurus nobilis leaf extract (LNE) against aluminum phosphide (AIP)-induced genotoxic and oxidative damages stress in cultured human blood cells in the presence of a metabolic activator (S9 mix). Materials and Methods: Sister chromatid exchange (SCE) and chromosome aberration (CA) assays were used to assess AlP-induced genotoxicity and to establish the protective effects of LNE. In addition, we determined total antioxidant capacity (TAC) and total oxidative status (TOS) levels in AlP and LNE treated cultures for biomonitoring the oxidative alterations. Results: There was significant increases (P < 0.05) in both SCE and CA frequencies of cultures treated with AlP as compared to controls. Our results also showed that AlP (58 mg/l) caused oxidative stress by altering TAC and TOS levels. However, co-application of LNE (25, 50, 100 and 200 mg/l) and AlP resulted in decreases of SCE, CA rates and TOS level and increases of TAC level as compared to the group treated with AlP alone. Conclusion: The preventive role of LNE in alleviating AlP-induced DNA and oxidative damages was indicated for the first time in the present study. PMID:23543905

  1. Lattice-mismatched In(0. 40)Al(0. 60)As window layers for indium phosphide solar cells

    SciTech Connect

    Jain, R.K.; Landis, G.A.; Wilt, D.M.; Flood, D.J.

    1993-11-01

    The efficiency of indium phosphide (InP) solar cells is limited by its high surface recombination velocity (approximately 10(exp 7) cm/s). This might be reduced by a wide-bandgap window layer. The performance of InP solar cells with wide-bandgap (1.8 eV) lattice-mismatched In(0.40)Al(0.60)As as a window layer was calculated. Because the required window layer thickness is less than the critical layer thickness, growth of strained (pseudomorphic) layers without interfacial misfit dislocations should be possible. Calculations using the PC-lD numerical code showed that the efficiencies of baseline and optimized p(+)n (p-on-n) cells are increased to more than 22 and 24 percent, (air mass zero (AMO), 25 C), respectively for a lattice-mismatched In(0.40)Al(0.60)As window layer of 10-nm thickness. Currently, most cell development work has been focused on n(+)p (n-on-p) structures although comparatively little improvement has been found for n(+)p cells.

  2. Acute liver failure due to zinc phosphide containing rodenticide poisoning: Clinical features and prognostic indicators of need for liver transplantation.

    PubMed

    Saraf, Vivek; Pande, Supriya; Gopalakrishnan, Unnikrishnan; Balakrishnan, Dinesh; Menon, Ramachandran N; Sudheer, O V; Dhar, Puneet; Sudhindran, S

    2015-07-01

    Zinc phosphide (ZnP) containing rodenticide poisoning is a recognized cause of acute liver failure (ALF) in India. When standard conservative measures fail, the sole option is liver transplantation. Records of 41 patients admitted to a single centre with ZnP-induced ALF were reviewed to identify prognostic indicators for requirement of liver transplantation. Patients were analyzed in two groups: group I (n = 22) consisted of patients who either underwent a liver transplant (n = 14) or died without a transplant (n = 8); group II (n = 19) comprised those who survived without liver transplantation. International normalized ratio (INR) in group I was 9 compared to 3 in group II (p < 0.001). Encephalopathy occurred only in group I. Model for End-Stage Liver Disease (MELD) score in group I was 41 compared to 24 in group II (p < 0.001). MELD score of 36 (sensitivity of 86.7 %, specificity of 90 %) or a combination of INR of 6 and encephalopathy (sensitivity of 100 %, specificity of 83 %) were the best indicators of mortality. Such patients should undergo urgent liver transplantation. PMID:26310868

  3. A review of episodes of zinc phosphide toxicosis in wild geese (Branta spp.) in Oregon (2004−2011)

    USGS Publications Warehouse

    Bildfell, Rob J.; Rumbeiha, Wilson K.; Schuler, Krysten L.; Meteyer, Carol U.; Wolff, Peregrine L.; Gillin, Colin M.

    2013-01-01

    Epizootic mortality in several geese species, including cackling geese (Branta hutchinsii) and Canada geese (Branta canadensis), has been recognized in the Willamette Valley of Oregon for over a decade. Birds are generally found dead on a body of water or are occasionally observed displaying neurologic clinical signs such as an inability to raise or control the head prior to death. Investigation of these epizootic mortality events has revealed the etiology to be accidental poisoning with the rodenticide zinc phosphide (Zn3P2). Gross and histologic changes are restricted to acute pulmonary congestion and edema, sometimes accompanied by distension of the upper alimentary tract by fresh grass. Geese are unusually susceptible to this pesticide; when combined with an epidemiologic confluence of depredation of specific agricultural crops by rodents and seasonal avian migration pathways, epizootic toxicosis may occur. Diagnosis requires a high index of suspicion, appropriate sample collection and handling, plus specific test calibration for this toxicant. Interagency cooperation, education of farmers regarding pesticide use, and enforcement of regulations has been successful in greatly decreasing these mortality events since 2009.

  4. Mitochondrial electron transport chain complexes, catalase and markers of oxidative stress in platelets of patients with severe aluminum phosphide poisoning.

    PubMed

    Anand, R; Sharma, D R; Verma, D; Bhalla, A; Gill, K D; Singh, S

    2013-08-01

    Aluminum phosphide (ALP), a widely used fumigant and rodenticide, leads to high mortality if ingested. Its toxicity is due to phosphine that is liberated when it comes in contact with moisture. The exact site or mechanism of action of phosphine is not known, although it is widely believed that it affects mitochondrial oxidative phosphorylation. Basic serum biochemical parameters, activity of mitochondrial complexes, antioxidant enzymes and parameters of oxidative stress were estimated in the platelets of 21 patients who developed severe poisoning following ALP ingestion. These parameters were compared with 32 healthy controls and with 22 patients with shock due to other causes (cardiogenic shock (11), septic shock (9) and hemorrhagic shock (2)). The serum levels of creatine kinase-muscle brain and lactate dehydrogenase were higher in patients poisoned with ALP, whereas a significant decrease was observed in the activities of mitochondrial complexes I, II and IV. The activity of catalase was lower but the activities of superoxide dismutase and glutathione peroxidase were unaffected in them. A significant increase in lipid peroxidation and protein carbonylation was observed, whereas total blood thiol levels were lower. In patients severely poisoned with ALP, not only cytochrome c oxidase but also other complexes are involved in mitochondrial electron transport, and enzymes are also inhibited. PMID:23821638

  5. Potential health and safety hazards associated with the production of cadmium telluride, copper indium diselenide, and zinc phosphide photovoltaic cells

    SciTech Connect

    Moskowitz, P.D.; Fthenakis, V.M.; Lee, J.C.

    1985-04-01

    In large-scale manufacture of cadmium telluride, copper indium diselenide, and zinc phosphide photovoltaic cells, the materials and equipment used may present potential health and safety hazards to workers and the public. These hazards were identified by reviewing data on process materials, availability of control technology, biomedical effects, and health and environmental standards. Quantitative estimates of material inputs and outputs, and control technology costs for selected processes were based on preliminary engineering designs for hypothetical 10-MWp/yr photovoltaic cell production facilities. In the fabrication of these devices, unusually large quantities of some toxic gases may be used; large demands for phosphine and hydrogen selenide are of special concern. Because projected usage of these materials is much larger than the current one, a thorough evaluation of engineering controls will be needed before the technologies are commercialized. These materials could also present occupational health hazards. Some management options to reduce occupational exposures to these materials are presented. Although specific federal and state regulations have not been promulgated for emissions from the photovoltaic industry, prudent engineering practice should be applied to all waste streams - solid, atmospheric, or liquid - containing toxic pollutants to limit discharges of these materials. Control costs for most atmospheric waste streams should not be large (<0.01 cent per watt); for phosphine, however, costs are potentially much larger (4.4 cents per watt). Some processes may also produce large quantities of solid waste defined as toxic or hazardous under US Environmental Protection Agency guidelines. Disposal costs for these materials are presented.

  6. PLEURAL EFFECTS OF INDIUM PHOSPHIDE IN B6C3F1 MICE: NONFIBROUS PARTICULATE INDUCED PLEURAL FIBROSIS

    PubMed Central

    Kirby, Patrick J.; Shines, Cassandra J.; Taylor, Genie J.; Bousquet, Ronald W.; Price, Herman C.; Everitt, Jeffrey I.; Morgan, Daniel L.

    2010-01-01

    The mechanism(s) by which chronic inhalation of indium phosphide (InP) particles causes pleural fibrosis is not known. Few studies of InP pleural toxicity have been conducted because of the challenges in conducting particulate inhalation exposures, and because the pleural lesions developed slowly over the 2-year inhalation study. The authors investigated whether InP (1 mg/kg) administered by a single oropharyngeal aspiration would cause pleural fibrosis in male B6C3F1 mice. By 28 days after treatment, protein and lactate dehydrogenase (LDH) were significantly increased in bronchoalveolar lavage fluid (BALF), but were unchanged in pleural lavage fluid (PLF). A pronounced pleural effusion characterized by significant increases in cytokines and a 3.7-fold increase in cell number was detected 28 days after InP treatment. Aspiration of soluble InCl3 caused a similar delayed pleural effusion; however, other soluble metals, insoluble particles, and fibers did not. The effusion caused by InP was accompanied by areas of pleural thickening and inflammation at day 28, and by pleural fibrosis at day 98. Aspiration of InP produced pleural fibrosis that was histologically similar to lesions caused by chronic inhalation exposure, and in a shorter time period. This oropharyngeal aspiration model was used to provide an initial characterization of the progression of pleural lesions caused by InP. PMID:19995279

  7. Lattice-mismatched In(0.40)Al(0.60)As window layers for indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Jain, Raj K.; Landis, Geoffrey A.; Wilt, David M.; Flood, Dennis J.

    1993-01-01

    The efficiency of indium phosphide (InP) solar cells is limited by its high surface recombination velocity (approximately 10(exp 7) cm/s). This might be reduced by a wide-bandgap window layer. The performance of InP solar cells with wide-bandgap (1.8 eV) lattice-mismatched In(0.40)Al(0.60)As as a window layer was calculated. Because the required window layer thickness is less than the critical layer thickness, growth of strained (pseudomorphic) layers without interfacial misfit dislocations should be possible. Calculations using the PC-lD numerical code showed that the efficiencies of baseline and optimized p(+)n (p-on-n) cells are increased to more than 22 and 24 percent, (air mass zero (AMO), 25 C), respectively for a lattice-mismatched In(0.40)Al(0.60)As window layer of 10-nm thickness. Currently, most cell development work has been focused on n(+)p (n-on-p) structures although comparatively little improvement has been found for n(+)p cells.

  8. The achievement of low contact resistance to indium phosphide: The roles of Ni, Au, Ge, and combinations thereof

    NASA Technical Reports Server (NTRS)

    Fatemi, Navid S.; Weizer, Victor G.

    1992-01-01

    We have investigated the electrical and metallurgical behavior of Ni, Au-Ni, and Au-Ge-Ni contacts on n-InP. We have found that very low values of contact resistivity rho(sub c) in the E-7 omega-sq cm range are obtained with Ni-only contacts. We show that the addition of Au to Ni contact metallization effects an additional order of magnitude reduction in rho(sub c). Ultra-low contact resistivities in the E-8 omega-sq cm range are obtained with both the Au-Ni and the Au-Ge-Ni systems, effectively eliminating the need for the presence of Ge in the Au-Ge-Ni system. The formation of various nickel phosphides at the metal-InP interface is shown to be responsible for the observed rho(sub c) values in the Ni and Au-Ni systems. We show, finally, that the order in which the constituents of Au-Ni and Au-Ge-Ni contacts are deposited has a significant bearing on the composition of the reaction products formed at the metal-InP interface and therefore on the contact resistivity at that interface.

  9. An electrocardiographic, molecular and biochemical approach to explore the cardioprotective effect of vasopressin and milrinone against phosphide toxicity in rats.

    PubMed

    Jafari, Abbas; Baghaei, Amir; Solgi, Reza; Baeeri, Maryam; Chamanara, Mohsen; Hassani, Shokoufeh; Gholami, Mahdi; Ostad, Seyed Nasser; Sharifzadeh, Moahmmad; Abdollahi, Mohammad

    2015-06-01

    The present study was conducted to identify the protective effect of vasopressin (AVP) and milrinone on cardiovascular function, mitochondrial complex activities, cellular ATP reserve, oxidative stress, and apoptosis in rats poisoned by aluminum phosphide (AlP). Rats were divided into five groups (n = 12) including control, AlP (12.5 mg/kg), AlP + AVP (2.0 Units/kg), AlP + milrinone (0.25 mg/kg) and AlP + AVP + milrinone. After treatment, the animals were connected to an electronic cardiovascular monitoring device to monitor electrocardiographic (ECG) parameter. Finally, oxidative stress biomarkers, mitochondrial complex activities, ADP/ATP ratio and apoptosis were evaluated on the heart tissues. Results indicated that AlP administration induced ECG abnormalities along with a decline in blood pressure and heart rate. AVP and milrinone significantly ameliorated these changes in all treated groups. Considerable protective effects on oxidative stress biomarkers, complex IV activity, ADP/ATP ratio and caspase-3 and -9 activities in treated groups were also found. These findings were supported by flow cytometry assay of cardiomyocytes. In conclusion, administration of AVP and milrinone, not only improve cardiovascular functions in AlP poisoned rats in the short time, but after a long time can also restore mitochondrial function and ATP level and reduce the oxidative damage, which prevent cardiomyocytes from entering the apoptotic phase. PMID:25796571

  10. Epitaxial dysprosium phosphide grown by gas-source and solid-source MBE on gallium arsenide substrates

    NASA Astrophysics Data System (ADS)

    Sadwick, L. P.; Lee, P. P.; Patel, M.; Nikols, M.; Hwu, R. J.; Shield, J. E.; Streit, D. C.; Brehmer, D.; McCormick, K.; Allen, S. J.; Gedridge, R. W.

    1996-07-01

    We report the first known study of the growth of epitaxial dysprosium phosphide (DyP) grown on gallium arsenide (GaAs). DyP is lattice matched to GaAs, with the room-temperature mismatch being less than 0.01%. We have grown DyP on GaAs by gas-source and by solid-source molecular beam epitaxy using custom-designed group V thermal cracker cells and group III high temperature effusion cells. X-ray diffraction results show the DyP epilayer to be (001) single crystal on GaAs(001) substrate. Electrical and optical measurements performed to date are inconclusive as to whether DyP is a semi-metal or a semiconductor with a small band gap. The undoped films are n-type with measured electron concentrations on the order of 5 × 10 19-6 × 10 20cm -3 with mobilities of 1-10 cm 2/V · s. {DyP}/{GaAs} is stable in air with no apparent oxidation taking place, even after months of exposure to ambient untreated air. Material and surface science properties measured for {DyP}/{GaAs} include Hall measurements, 2ϑ and double-crystal X-ray diffraction spectra and photothermal deflection spectroscopy.

  11. Boron nitride phosphide thin films grown on quartz substrate by hot-filament and plasma-assisted chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Zhang, X. W.; Xu, S. Y.; Han, G. R.

    2004-10-01

    Boron nitride phosphide films are, for the first time, grown on transparent quartz substrate by hot filament and radio-frequency plasma co-assisted chemical vapor deposition technique. XPS, XRD, SEM, and UV measurements are performed to study the chemical composition, crystallization, microstructure, and optical absorption, respectively. A centipede-like microstructure and undulating ground morphology on the film surface are observed, and their growth mechanism is speculated upon. The chemical composition is determined as BN1-xPx, whose characteristic XRD peak is preliminarily identified. The optical band gap can be modulated between 5.52 eV and 3.74 eV, simply by adjusting the phosphorus content in BN1-xPx through modifying the PH3 flux during the film-deposition process. The merits of the BN1-xPx film, such as high ultraviolet photoelectric sensitivity with negligible sensitivity in the visible region, modifiable wide optical band gap, and good adhesion on transparent substrate, suggest potential applications for ultraviolet photo-electronics.

  12. Silver catalyzed gallium phosphide nanowires integrated on silicon and in situ Ag-alloying induced bandgap transition.

    PubMed

    Huang, Kangrong; Zhang, Zhang; Zhou, Qingwei; Liu, Liwei; Zhang, Xiaoyan; Kang, Mengyang; Zhao, Fuli; Lu, Xubing; Gao, Xingsen; Liu, Junming

    2015-01-26

    In this work, we demonstrate a silver catalyzed heteroepitaxial growth of gallium phosphide nanowires (GaP NWs) on silicon. The morphology and growth direction of GaP NWs on differently orientated Si substrates were investigated. From crystallographic analysis, we inferred that Ag from catalyst is incorporated into the GaP during the chemical beam epitaxy (CBE) process. Using the PL spectrum and time-resolved emission spectroscopy, the optical properties of Ag-catalyzed GaP NWs were greatly modified, with bandgap transitions in the blue range. The Raman characterizations further confirmed the Ag incorporation into GaP during the growth. From the bandgap calculations, it was deduced that Ag was substituted on the Ga site with bandgap broadening. The in situ Ag-alloying during the growth of Ag-catalyzed GaP NWs greatly modified the band structure of GaP, and could lead to further applications in optoelectronics for low-dimensional GaP-based nanomaterials. PMID:26044077

  13. Solar Hydrogen Production Using Molecular Catalysts Immobilized on Gallium Phosphide (111)A and (111)B Polymer-Modified Photocathodes.

    PubMed

    Beiler, Anna M; Khusnutdinova, Diana; Jacob, Samuel I; Moore, Gary F

    2016-04-20

    We report the immobilization of hydrogen-producing cobaloxime catalysts onto p-type gallium phosphide (111)A and (111)B substrates via coordination to a surface-grafted polyvinylimidazole brush. Successful grafting of the polymeric interface and subsequent assembly of cobalt-containing catalysts are confirmed using grazing angle attenuated total reflection Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Photoelectrochemical testing in aqueous conditions at neutral pH shows that cobaloxime modification of either crystal face yields a similar enhancement of photoperformance, achieving a greater than 4-fold increase in current density and associated rates of hydrogen production as compared to results obtained using unfunctionalized electrodes tested under otherwise identical conditions. Under simulated solar illumination (100 mW cm(-2)), the catalyst-modified photocathodes achieve a current density ≈ 1 mA cm(-2) when polarized at 0 V vs the reversible hydrogen electrode reference and show near-unity Faradaic efficiency for hydrogen production as determined by gas chromatography analysis of the headspace. This work illustrates the modularity and versatility of the catalyst-polymer-semiconductor approach for directly coupling light harvesting to fuel production and the ability to export this chemistry across distinct crystal face orientations. PMID:26998554

  14. Substituent directed selectivity in anion recognition by a new class of simple osmium-pyrazole derived receptors.

    PubMed

    Das, Ankita; Mondal, Prasenjit; Dasgupta, Moumita; Kishore, Nand; Lahiri, Goutam Kumar

    2016-02-14

    The present article deals with the structurally, spectroscopically and electrochemically characterised osmium-bipyridyl derived complexes [(bpy)2Os(II)(HL1)Cl]ClO4 [1]ClO4 and [(bpy)2Os(II)(HL2)Cl]ClO4 [2]ClO4 incorporating neutral and monodentate pyrazole derivatives (HL) with one free NH function (bpy = 2,2'-bipyridine, HL1 = pyrazole, HL2 = 3,5-dimethylpyrazole). The crystal structures of [1]ClO4 and [2]ClO4 reveal intramolecular hydrogen bonding interactions between the free NH proton of HL and the equatorially placed Cl(-) ligand (N-HCl) with donor-acceptor distances of 3.114(7) Å and 3.153(6) Å as well as intermolecular hydrogen bonding interactions between the NH proton and one of the oxygen atoms of ClO4(-) (N-HO) with donor-acceptor distances of 2.870(10) Å and 3.024(8) Å, respectively. The effect of hydrogen bonding interactions has translated into the less acidic nature of the NH proton of the coordinated HL with estimated pKa > 12. 1(+) and 2(+) exhibit reversible Os(II)/(III) and irreversible Os(III)/(IV) processes in CH3CN within ± 2.0 V versus SCE. The effect of 3,5-dimethyl substituted HL2 on 2(+) has been reflected in the appreciable lowering (40 mV) of the Os(II/III) potential, along with the further decrease in the acidity of the NH proton (pKa > 13.0) with regard to HL1 coordinated 1(+) (pKa: ∼ 12.3). The electronic spectral features of Os(ii) (1(+)/2(+)) and electrochemically generated Os(III) (1(2+)/2(2+)) derived complexes have been analysed by TD-DFT calculations. The efficacy of the 1(+) and 2(+) encompassing free NH proton towards the anion recognition process has been evaluated by different experimental investigations using a wide variety of anions. It however establishes that receptor 1(+) can recognise both F(-) and OAc(-) in acetonitrile solution, while 2(+) is exclusively selective for the F(-) ion. PMID:26733437

  15. Theoretical modeling, near-optimum design and predicted performance of n(+)pp(+) and p(+)nn(+) indium phosphide homojunction solar cells

    NASA Technical Reports Server (NTRS)

    Goradia, Chandra; Thesling, William; Weinberg, Irving

    1991-01-01

    Using a detailed simulation model of p(+)nn(+) and n(+)pp(+) indium phosphide (InP) homojunction solar cells, extensive parametric variation computer simulation runs are conducted to help arrive at near-optimum designs of these two solar cell configurations. Values of all the geometrical and material parameters corresponding to the near-optimal designs of both these configurations are presented. For each configuration, results are given for parametric variation runs showing how the performance parameters JSC, VOC, and eta vary with each of the cell parameters for the near-optimally designed cell.

  16. 9,10-phenanthrenesemiquinone radical complexes of ruthenium(III), osmium(III) and rhodium(III) and redox series.

    PubMed

    Biswas, Manas Kumar; Patra, Sarat Chandra; Maity, Amarendra Nath; Ke, Shyue-Chu; Weyhermüller, Thomas; Ghosh, Prasanta

    2013-05-14

    Reactions of 9,10-phenanthrenequinone (PQ) in toluene with [M(II)(PPh3)3X2] at 298 K afford green complexes, trans-[M(PQ)(PPh3)2X2] (M = Ru, X = Cl, 1; M = Os, X = Br, 2) in moderate yields. Reaction of anhydrous RhCl3 with PQ and PPh3 in boiling ethanol affords the dark brown paramagnetic complex, cis-[Rh(PQ)(PPh3)2Cl2] (3) in good yields. Diffusion of iodine solution in n-hexane to the trans-[Os(PQ) (PPh3)2(CO)(Br)] solution in CH2Cl2 generates the crystals of trans-[Os(PQ)(PPh3)2(CO)(Br)](+)I3(-), (4(+))I3(-)), in lower yields. Single crystal X-ray structure determinations of 1·2toluene, 2·CH2Cl2 and 4(+)I3(-), UV-vis/NIR absorption spectra, EPR spectra of 3, electrochemical activities and DFT calculations on 1, 2, trans-[Ru(PQ)(PMe3)2Cl2] (1Me), trans-[Os(PQ)(PMe3)2Br2] (2Me), cis-[Rh(PQ)(PMe3)2Cl2] (3Me) and their oxidized and reduced analogues including trans-[Os(PQ)(PMe3)2(CO)(Br)](+) (4Me(+)) substantiated that 1-3 are the 9,10-phenanthrenesemiquinone radical (PQ(˙-)) complexes of ruthenium(III), osmium(III) and rhodium(III) and are defined as trans/cis-[M(III)(PQ(˙-))(PPh3)2X2] with a minor contribution of the resonance form trans/cis-[M(II)(PQ)(PPh3)2X2]. Two comparatively longer C-O (1.286(4) Å) and the shorter C-C lengths (1.415(7) Å) of the OO-chelate of 1·2toluene and 2·CH2Cl2 and the isotropic fluid solution EPR signal at g = 1.999 of 3 are consistent with the existence of the reduced PQ(˙-) ligand in 1-3 complexes. Anisotropic EPR spectra of the frozen glasses (g11 = g22 = 2.0046 and g33 = 1.9874) and solids (g11 = g22 = 2.005 and g33 = 1.987) instigate the contribution of the resonance form, cis-[Rh(II)(PQ)(PPh3)2Cl2] in 3. DFT calculations established that the closed shell singlet (CSS) solutions of 1Me and 2Me are unstable due to open shell singlet (OSS) perturbation. However, the broken symmetry (BS) (1,1) Ms = 0 solutions of 1Me and 2Me are respectively 22.6 and 24.2 kJ mole(-1) lower in energy and reproduced the experimental bond

  17. Escape of unradiogenic osmium during sub-aerial lava degassing: Evidence from fumarolic deposits, Piton de la Fournaise, Réunion Island

    NASA Astrophysics Data System (ADS)

    Gannoun, Abdelmouhcine; Vlastélic, Ivan; Schiano, Pierre

    2015-10-01

    This study presents new Re-Os isotope and elemental data in gas condensates and corresponding lavas in order to examine the geochemical behavior of these two elements during magma degassing at Piton de la Fournaise, Réunion Island. Gas sublimates formed between 2007 and 2011 at temperature ranging from 400 to ca. 100 °C include Na-K sulfate (aphthitalite), Na sulfate (thenardite), Ca-Cu sulfate (e.g. gypsum), Ca-Mg-Al-Fe fluoride (e.g. ralstonite) and native sulfur. The high temperature deposits show trace element typical of volcanic gas with high enrichment in Re (24 to 79 ppb), almost two order of magnitude higher than the corresponding lavas but with Os abundances similar to those of the lavas (14-132 ppt). In contrast the Os contents of the low temperature fluoride deposits (13-77 ppb) are higher than any of the other condensates. The fluorides are also enriched in Re, albeit to lesser extent than Os (2.9-15.3 ppb). Based on high-temperature samples, the fluid/melt partition coefficients estimated for Re and Os are 100 ± 80 and 1 ± 2, respectively. Considering 1% of fluid loss, these partition coefficients translate into emanation coefficients of 0.50 (0.17-0.65) for Re and 0.01 (0-0.03) for Os. These results indicate that Re, unlike Os, is highly volatile at Piton de la Fournaise. Osmium isotopic compositions of samples collected at medium and low temperature (<350 °C) are very uniform and unfractionated (187Os/188Os between 0.130-0.135) and plot within the range of the April 2007 lava flow and the historical lavas of Piton de la Fournaise (i.e. 0.130-0.137). However the highest temperature condensates (Na-K sulfates with T of 384-400°C) yield lower 187Os/188Os ratios (i.e. 0.124-0.129) within the field of mantle signal. Such unradiogenic compositions are best explained if old mantle sulfides occur in lavas and contribute to volcanic gases. Within the general frame of osmium mantle geochemistry, loss of unradiogenic Os during magmas degassing could help

  18. Monometallic osmium(II) complexes with bis(N-methylbenzimidazolyl)benzene or -pyridine: a comparison study with ruthenium(II) analogues.

    PubMed

    Shao, Jiang-Yang; Zhong, Yu-Wu

    2013-06-01

    Seven bis-tridentate osmium complexes with Mebib or Mebip (Mebib is the 2-deprotonated form of 1,3-bis(N-methylbenzimidazolyl)benzene and Mebip is bis(N-methylbenzimidazolyl)pyridine) have been prepared, and their electrochemical and spectroscopic properties are compared with ruthenium structural analogues. Among them, four complexes have the [Os(NCN)(NNN)]-type coordination, including [Os(Mebib)(Mebip)](PF6)2 (1(PF6)2), [Os(dpb)(Mebip)](PF6) (2(PF6), dpb is the 2-deprotonated form of 1,3-di(pyrid-2-yl)benzene), [Os(Mebib)(ttpy)](PF6) (3(PF6), ttpy = 4'-tolyl-2,2':6',2"-terpyridine), and [Os(dpb)(ttpy)](PF6) (4(PF6)). The other three complexes are [Os(Mebip)2](PF6)2 (5(PF6)2), [Os(Mebip)(tpy)](PF6)2 (6(PF6)2, tpy = 2,2':6',2"-terpyridine), and [Os(ttpy)2](PF6)2 (7(PF6)2) with the [Os(NNN)(NNN)]-type coordination. Single crystals of 2(PF6) and 6(PF6)2 have been obtained, and their structures are studied by X-ray crystallographic analysis. The Os(II/III) redox potentials of 1(PF6)2 to 7(PF6)2 progressively increase from +0.04, +0.23, +0.24, +0.36, +0.56, +0.79 to +0.94 V vs Ag/AgCl, which are 200-300 mV less positive relative to the Ru(II/III) potentials of their ruthenium counterparts. The highest occupied molecular orbital energy levels of 1(+)-7(2+) are calculated to vary in a descending order. The ruthenium and osmium complexes have singlet metal-to-ligand charge-transfer (MLCT) transitions of similar energies and band shapes, while the osmium complexes display additional (3)MLCT transitions in the lower-energy region. Complexes 6(PF6)2 and 7(PF6)2 emit weakly at 780 and 740 nm, respectively. Complex 1(PF6)2 was synthesized as the oxidized Os(III) salt because of the low Os(II/III) potential. The transformation of 1(2+) to 1(+) by chemical reduction or electrolysis led to the emergence of the (1)MLCT transitions in the visible region. PMID:23688019

  19. Oxidative stress determined through the levels of antioxidant enzymes and the effect of N-acetylcysteine in aluminum phosphide poisoning

    PubMed Central

    Agarwal, Avinash; Robo, Roto; Jain, Nirdesh; Gutch, Manish; Consil, Shuchi; Kumar, Sukriti

    2014-01-01

    Introduction: The primary objective of this study was to determine the serum level of antioxidant enzymes and to correlate them with outcome in patients of aluminum phosphide (ALP) poisoning and, secondly, to evaluate the effect of N-acetylcysteine (NAC) given along with supportive treatment of ALP poisoning. Design: We conducted a cohort study in patients of ALP poisoning hospitalized at a tertiary care center of North India. The treatment group and control group were enrolled during the study period of 1 year from May 2011 to April 2012. Interventions: Oxidative stress was evaluated in each subject by estimating the serum levels of the enzymes, viz. catalase, superoxide dismutase (SOD) and glutathione reductase (GR). The treatment group comprised of patients who were given NAC in addition to supportive treatment (magnesium sulfate and vasopressors, if required), while in the control group, only supportive treatment was instituted. The primary endpoint of the study was the survival of the patients. Measurements and Results: The baseline catalase (P = 0.008) and SOD (P < 0.01) levels were higher among survivors than non-survivors. Of the total patients in the study, 31 (67.4%) expired and 15 (32.6%) survived. Among those who expired, the mean duration of survival was 2.92 ± 0.40 days in the test group and 1.82 ± 0.33 days in the control group (P = 0.043). Conclusions: This study suggests that the baseline level of catalase and SOD have reduced in ALP poisoning, but baseline GR level has not suppressed but is rather increasing with due time, and more so in the treatment group. NAC along with supportive treatment may have improved survival in ALP poisoning. PMID:25316977

  20. N-acetylcysteine, Ascorbic Acid, and Methylene Blue for the Treatment of Aluminium Phosphide Poisoning: Still Beneficial?

    PubMed Central

    Gheshlaghi, Farzad; Lavasanijou, Mohamad Reza; Moghaddam, Noushin Afshar; Khazaei, Majid; Behjati, Mohaddeseh; Farajzadegan, Ziba; Sabzghabaee, Ali Mohammad

    2015-01-01

    Objectives: Intentional and accidental intoxication with aluminium phosphide (ALP) remains a clinical problem, especially in the Middle East region. Considering the high mortality rate besides lack of any recommended first option drug for its treatment, this study was aimed to compare the therapeutic effects of N-acetylcysteine (NAC), vitamin C (Vit C), and methylene blue; both in isolate and also in combination, for the treatment of ALP intoxication in a rat model. Materials and Methods: In this experimental animal study, 80 male Wistar rats in eight groups were intoxicated with ALP (12.5 mg/kg) and treated with a single dose of NAC (100 mg/kg) or Vit C (500–1,000 mg/kg) or methylene blue (1 mg/kg/5 min, 0.1%) or two of these agents or all three of them (controls were not treated). Rats were monitored regarding the parameters of drug efficacy as increased survival time and reduced morbidity and mortality rate for 3 consecutive days to ensure toxin neutralization. Macroscopic changes were recorded and biopsy sections were taken from brain, cerebellum, kidney, liver, and heart for microscopic evaluation regarding cellular hypoxia. Results: The mean survival times of rats exposed to ALP and treated with VitC + NAC was 210.55±236.22 minutes. In analysis of survival times, there was a significant difference between Group 5 which received VitC + NAC and the other groups (P < 0.01). Serum magnesium levels after death were higher than normal (P = 0.01). Conclusions: Despite the higher survival rate of antioxidant-treated rats compared with controls, this difference was not statistically significant. PMID:26862259

  1. Electron-phonon superconductivity in the ternary phosphides Ba M2P2 (M =Ni,Rh,and Ir)

    NASA Astrophysics Data System (ADS)

    Karaca, Ertuǧrul; Tütüncü, H. M.; Srivastava, G. P.; Uǧur, S.

    2016-08-01

    Ab initio plane-wave pseudopotential calculations of electronic and vibrational properties have been carried out for the ternary phosphides Ba M2P2 (M =Ni,Rh and Ir) with a ThCr2Si2 -type structure. The calculated electronic results show the metallic character of Ba M2P2 , and the plots of total and partial density of states of Ba M2P2 exhibit strong hybridization between the d states of the M atom and the p states of the P atom below the Fermi energy. Differences in the phonon spectrum and density of states both in the acoustical and optical ranges for these compounds are presented and discussed. The Eliashberg spectral function for these compounds has been calculated by using a linear response approach based on the density functional theory. By integrating the Eliashberg spectral function, the average electron-phonon coupling parameter (λ ) is determined to be 0.61 for BaNi2P2 , 0.55 for BaIr2P2 , and 0.43 for BaRh2P2 . Using the calculated values of λ and the logarithmically averaged phonon frequency ωln the superconducting critical temperature (Tc) values for BaNi2P2,BaIr2P2 , and BaRh2P2 are obtained to be 2.80, 1.97, and 0.70 K, respectively, which compare very well with their experimental values of 3.0, 2.1, and 1.0 K.

  2. Solvothermal preparation of tin phosphide as a long-life anode for advanced lithium and sodium ion batteries

    NASA Astrophysics Data System (ADS)

    Liu, Shuling; Zhang, Hongzhe; Xu, Liqiang; Ma, Lanbing; Chen, Xiaoxia

    2016-02-01

    Tin phosphide (Sn4P3) nanoparticles with different sizes are synthesized via a facile solvothermal method at 180 °C for 10 h. The as-prepared Sn4P3 nanoparticles have an average size of about 15 nm. Meanwhile, their size could be easily controlled by the solvent ratio. The long cycle stability and rate performance of the as-obtained Sn4P3 nanoparticles have been tested as an anode material for lithium ion batteries for the first time. Electrochemical measurements show that the Sn4P3 nanoparticles with a smallest size give the best cycling and rate performances. They deliver a discharge capacity of 612 mAh g-1 after 10 cycles and could still maintain 442 mAh g-1 after 320 cycles at the current density of 100 mA g-1 within voltage limit of 0.01-3.0 V. Even after 200 cycles at a current density of 200 mA g-1, the specific capacity still could be remained at 315 mAh g-1. The improved electrochemical performances of Sn4P3 electrode might be largely attributed to their small-size. Furthermore, the as-prepared Sn4P3 nanoparticles have also been tested as an anode material for Na-ion batteries, this Sn4P3 anode can deliver a reversible capacity of 305 mAh g-1 after 10 cycles at the current density of 50 mA g-1.

  3. Oxidative Cyclization of 1,5-Dienes with Hydrogen Peroxide Catalyzed by an Osmium(III) Complex: Synthesis of cis-Tetrahydrofurans.

    PubMed

    Sugimoto, Hideki; Kanetake, Takayuki; Maeda, Kazuki; Itoh, Shinobu

    2016-03-18

    Stereoselective oxidative cyclization of 1,5-dienes with hydrogen peroxide catalyzed by [Os(III)(OH)(H2O)(L-N4Me2)](PF6)2 (1: L-N4Me2 = N,N'-dimethyl-2,11-diaza-[3,3](2,6)pyridinophane) is explored. 1,5-Dienes involving geraniol derivatives are converted to the corresponding tetrahydrofurans in modest to high yields. The products exclusively have the cis-conformation with respect to the substituents at the 2- and 5-positions of the tetrahydrofuran ring. The products also have a syn-conformation with respect to the furan oxygen atom and the hydroxyl groups. Mechanistic studies including a direct reaction of the oxo-hydroxo-osmium(V) complex, 2, with a dihydroxylated geraniol derivative are performed. PMID:26950609

  4. Subsurface modifications in indium phosphide induced by single and multiple femtosecond laser pulses: A study on the formation of periodic ripples

    SciTech Connect

    Couillard, M.; Borowiec, A.; Haugen, H. K.; Preston, J. S.; Griswold, E. M.; Botton, G. A.

    2007-02-01

    We use cross-sectional transmission electron microscopy to study the damage induced below the surface of indium phosphide (InP) samples by single and multiple femtosecond laser pulses with a photon energy lower than the InP band gap. Single-pulse irradiation creates a {approx}100 nm deep crater with a resolidified surface layer consisting of quasiamorphous indium phosphide. The resolidified layer has a thickness of {approx}60 nm at the center and extends laterally beyond the edge of the crater rim. Exposure to multiple femtosecond pulses of 2050 nm center wavelength results in the formation of laser-induced periodic surface structures (LIPSS) with two different periods, one ({approx}1730 nm) less than but close to the laser wavelength and one ({approx}470 nm) four times smaller. Segregation beneath both types of ripples leads to the formation of In-rich particles embedded in the resolidified surface layer. Extended defects are detected only below the center of the multiple-pulse crater and their distribution appears to be correlated with the LIPSS modulation. Finally, LIPSS formation is discussed in terms of the observed subsurface microstructures.

  5. Tailored surface structure of LiFePO4/C nanofibers by phosphidation and their electrochemical superiority for lithium rechargeable batteries.

    PubMed

    Lee, Yoon Cheol; Han, Dong-Wook; Park, Mihui; Jo, Mi Ru; Kang, Seung Ho; Lee, Ju Kyung; Kang, Yong-Mook

    2014-06-25

    We offer a brand new strategy for enhancing Li ion transport at the surface of LiFePO4/C nanofibers through noble Li ion conducting pathways built along reduced carbon webs by phosphorus. Pristine LiFePO4/C nanofibers composed of 1-dimensional (1D) LiFePO4 nanofibers with thick carbon coating layers on the surfaces of the nanofibers were prepared by the electrospinning technique. These dense and thick carbon layers prevented not only electrolyte penetration into the inner LiFePO4 nanofibers but also facile Li ion transport at the electrode/electrolyte interface. In contrast, the existing strong interactions between the carbon and oxygen atoms on the surface of the pristine LiFePO4/C nanofibers were weakened or partly broken by the adhesion of phosphorus, thereby improving Li ion migration through the thick carbon layers on the surfaces of the LiFePO4 nanofibers. As a result, the phosphidated LiFePO4/C nanofibers have a higher initial discharge capacity and a greatly improved rate capability when compared with pristine LiFePO4/C nanofibers. Our findings of high Li ion transport induced by phosphidation can be widely applied to other carbon-coated electrode materials. PMID:24786736

  6. Evaluation of the rhenium-osmium geochronometer in the Phosphoria petroleum system, Bighorn Basin of Wyoming and Montana, USA

    USGS Publications Warehouse

    Lillis, Paul G.; Selby, David

    2013-01-01

    Rhenium-osmium (Re-Os) geochronometry is applied to crude oils derived from the Permian Phosphoria Formation of the Bighorn Basin in Wyoming and Montana to determine whether the radiogenic age reflects the timing of petroleum generation, timing of migration, age of the source rock, or the timing of thermochemical sulfate reduction (TSR). The oils selected for this study are interpreted to be derived from the Meade Peak Phosphatic Shale and Retort Phosphatic Shale Members of the Phosphoria Formation based on oil-oil and oil-source rock correlations utilizing bulk properties, elemental composition, δ13C and δ34S values, and biomarker distributions. The δ34S values of the oils range from -6.2‰ to +5.7‰, with oils heavier than -2‰ interpreted to be indicative of TSR. The Re and Os isotope data of the Phosphoria oils plot in two general trends: (1) the main trend (n = 15 oils) yielding a Triassic age (239 ± 43 Ma) with an initial 187Os/188Os value of 0.85 ± 0.42 and a mean square weighted deviation (MSWD) of 1596, and (2) the Torchlight trend (n = 4 oils) yielding a Miocene age (9.24 ± 0.39 Ma) with an initial 187Os/188Os value of 1.88 ± 0.01 and a MSWD of 0.05. The scatter (high MSWD) in the main-trend regression is due, in part, to TSR in reservoirs along the eastern margin of the basin. Excluding oils that have experienced TSR, the regression is significantly improved, yielding an age of 211 ± 21 Ma with a MSWD of 148. This revised age is consistent with some studies that have proposed Late Triassic as the beginning of Phosphoria oil generation and migration, and does not seem to reflect the source rock age (Permian) or the timing of re-migration (Late Cretaceous to Eocene) associated with the Laramide orogeny. The low precision of the revised regression (±21 Ma) is not unexpected for this oil family given the long duration of generation from a large geographic area of mature Phosphoria source rock, and the possible range in the initial 187Os/188Os

  7. Rhenium - osmium heterogeneity of enriched mantle basalts explained by composition and behaviour of mantle-derived sulfides

    NASA Astrophysics Data System (ADS)

    Harvey, J.; Dale, C. W.; Gannoun, A.; Burton, K. W.

    2010-12-01

    Analyses of enriched mantle (EM) -basalts, using lithophile element-based isotope systems have long provided evidence for discrete, but variable mantle reservoirs [1]. Upon partial melting, the isotopic fingerprint of each reservoir is imparted upon the partial melt produced. However, recent work involving the Re-Os isotope systematics of EM-basalts [2] suggests that it may not be so simple to delimit these previously well defined mantle reservoirs; the “mantle zoo” [3] may contain more reservoirs than previously envisaged. However, a simple model, with varying contributions from two populations of compositionally distinct mantle sulfides can readily account for the observed heterogeneities in Re-Os isotope systematics of such basalts without additional mantle reservoirs. Rhenium-osmium elemental and isotopic analyses of individual sulfide grains separated from spinel lherzolites from Kilbourne Hole, NM, USA demonstrate that two discrete populations of mantle sulfide exist in terms of both Re-Os systematics and textural relationship with co-existing silicates. One population, with a rounded morphology, is preserved in silicate grains and typically possesses high [Os], low [Re] with unradiogenic, typically sub-chondritic, 187Os/188Os attributable to long term isolation in a low-Re environment. By contrast, irregular-shaped sulfides, preserved along silicate grain boundaries, possess low [Os], higher [Re] and a wider range of, but generally supra-chondritic, 187Os/188Os ([Os] typically ≤ 1-2 ppm, 187Os/188Os ≤ 0.3729; this study). This population is thought to represent metasomatic sulfide (e.g. [4,5]). Uncontaminated silicate phases contain negligible Os (<100 ppt) therefore the Os elemental and isotope composition of basalts is dominated by volumetrically insignificant sulfide ([Os] ≤ 37 ppm, this study). During the early stages of partial melting, supra-chondritic interstitial sulfides are mobilized and incorporated into the melt, adding their radiogenic

  8. Ruthenium, osmium and rhodium complexes of 1,4-diaryl 1,4-diazabutadiene: radical versus non-radical states.

    PubMed

    Chandra Patra, Sarat; Saha Roy, Amit; Manivannan, Vadivelu; Weyhermüller, Thomas; Ghosh, Prasanta

    2014-09-28

    Ruthenium, osmium and rhodium complexes of 1,4-di(3-nitrophenyl)-1,4-diazabutadiene (LDAB) of types trans-[RuII(LDAB)(PPh3)2Cl2] (1), trans-[OsII(LDAB)(PPh3)2Br2] (2) and trans-[Rh(LDAB)(PPh3)2Cl2] (3) are isolated and characterized by elemental analyses, IR, mass and 1H NMR spectra including the single crystal X-ray structure determination of 1·2toluene. The α-diimine fragment of the LDAB ligand in 1·2toluene is deformed, showing a relatively longer -C=N- bond, 1.320 Å, and a shorter =CH–CH= bond, 1.395 Å. Density functional theory (DFT) calculations on trans-[Ru(LDAB)(PMe3)2Cl2] (1Me) and trans-[Os(LDAB)(PMe3)2Br2] (2Me) with singlet spin states authenticated that the closed shell singlet state (CSS) solutions of 1 and 2 are stable and no perturbation occurs because of the diradical open shell singlet (OSS) state. The EPR spectra of 3 and the Mulliken spin density distribution obtained from the DFT calculation on trans-[Rh(LDAB)(PMe3)2Cl2] (3Me) imply that the ground electronic state of 3 can be defined by the [RhIII(LDAB˙−)(PPh3)2Cl2] (3RhL˙) ↔ [RhII(LDAB)(PPh3)2Cl2] (3Rh˙L) resonating states. In solid, the contribution of 3RhL˙ is higher and the gav is 2.018 with Δg = 0.10, whereas in frozen glasses the contribution of 3Rh˙L is higher and the gav is 2.026 with Δg (frozen glasses) = 0.13. The g parameters of the electrogenerated [1]+ (g1 = 2.456, g2 = 2.128 and g3 = 1.624, Δg = 0.824), [2]+ (g1 = 2.599, g2 = 2.041 and g3 = 1.965, Δg = 0.634), [1]− (g1 = 2.138, g2 = 2.109, g3 = 1.978 and Δg = 0.160) and [2]− (g1 = 2.168, g2 = 2.097, g3 = 1.987 and Δg = 0.181) ions and the spin density distributions obtained from the DFT calculations on [1Me]+, [2Me]+, [1Me]− and [2Me]− reveal that the reversible anodic peaks of 1 and 2 at 0.11 and 0.34 V, referenced versus Fc+/Fc couple, are due to the M(III)/M(II) redox couple, while the reversible cathodic waves at −1.27 V and −0.82 V of 1 and 2 are caused by the LDAB/LDAB˙− redox couple

  9. Ruthenium, rhodium, osmium, and iridium complexes of osazones (osazones = bis-arylhydrazones of glyoxal): radical versus nonradical states.

    PubMed

    Patra, Sarat Chandra; Weyhermüller, Thomas; Ghosh, Prasanta

    2014-03-01

    Phenyl osazone (L(NHPh)H2), phenyl osazone anion radical (L(NHPh)H2(•-)), benzoyl osazone (L(NHCOPh)H2), benzoyl osazone anion radical (L(NHCOPh)H2(•-)), benzoyl osazone monoanion (L(NCOPh)HMe(-)), and anilido osazone (L(NHCONHPh)HMe) complexes of ruthenium, osmium, rhodium, and iridium of the types trans-[Os(L(NHPh)H2)(PPh3)2Br2] (3), trans-[Ir(L(NHPh)H2(•-))(PPh3)2Cl2] (4), trans-[Ru(L(NHCOPh)H2)(PPh3)2Cl2] (5), trans-[Os(L(NHCOPh)H2)(PPh3)2Br2] (6), trans- [Rh(L(NHCOPh)H2(•-))(PPh3)2Cl2] (7), trans-[Rh(L(NHCOPh)HMe(-))(PPh3)2Cl]PF6 ([8]PF6), and trans-[Ru(L(NHCONHPh)HMe)(PPh3)2Cl]Cl ([9]Cl) have been isolated and compared (osazones = bis-arylhydrazones of glyoxal). The complexes have been characterized by elemental analyses and IR, mass, and (1)H NMR spectra; in addition, single-crystal X-ray structure determinations of 5, 6, [8]PF6, and [9]Cl have been carried out. EPR spectra of 4 and 7 reveal that in the solid state they are osazone anion radical complexes (4, gav = 1.989; 7, 2.028 (Δg = 0.103)), while in solution the contribution of the M(II) ions is greater (4, gav = 2.052 (Δg = 0.189); 7, gav = 2.102 (Δg = 0.238)). Mulliken spin densities on L(NHPh)H2 and L(NHCOPh)H2 obtained from unrestricted density functional theory (DFT) calculations on trans-[Ir(L(NHPh)H2)(PMe3)2Cl2] (4(Me)) and trans-[Rh(L(NHCOPh)H2)(PMe3)2Cl2] (7(Me)) in the gas phase with doublet spin states authenticated the existence of L(NHPh)H2(•-) and L(NHCOPh)H2(•-) anion radicals in 4 and 7 coordinated to iridium(III) and rhodium(III) ions. DFT calculations on trans-[Os(L(NHPh)H2)(PMe3)2Br2] (3(Me)), trans-[Os(L(NHCOPh)H2)(PMe3)2Br2] (6(Me)), and trans-[Ru(L(NHCONHPh)HMe(-))(PMe3)2Cl] [9(Me)](+) with singlet spin states established that the closed-shell singlet state (CSS) solutions of 3, 5, 6, and [9]Cl are stable. The lower value of M(III)/M(II) reduction potentials and lower energy absorption bands corroborate the higher extent of mixing of d orbitals with the π* orbital

  10. Metal-rich phosphides RE{sub 5}Ir{sub 19}P{sub 12} with Sc{sub 5}Co{sub 19}P{sub 12} type structure

    SciTech Connect

    Pfannenschmidt, Ulrike; Rodewald, Ute Ch.; Hoffmann, Rolf-Dieter; Poettgen, Rainer

    2011-10-15

    The iridium-rich phosphides RE{sub 5}Ir{sub 19}P{sub 12} (RE=Sc, Y, La-Nd, Sm-Lu) with Sc{sub 5}Co{sub 19}P{sub 12} type structure, space group P62-bar m were synthesized by solid state reactions of the elements in tantalum crucibles. Well shaped single crystals were obtained in bismuth fluxes. All phosphides were characterized on the basis of X-ray powder data. The structures of RE{sub 5}Ir{sub 19}P{sub 12} with RE=Sc, La, Ce, Dy, Er, Tm, and Yb were refined from single crystal diffractometer data. The complex structure of these phosphides can be described by an intergrowth of simpler ThCr{sub 2}Si{sub 2} and SrPtSb related slabs. Striking structural motifs of the RE{sub 5}Ir{sub 19}P{sub 12} structures are slightly distorted tricapped trigonal prisms of the metal atoms around the phosphorus atoms. The iridium and phosphorus atoms build up three-dimensional [Ir{sub 19}P{sub 12}] polyanionic networks (230-286 pm Ir-P and 282-296 pm Ir-Ir in La{sub 5}Ir{sub 19}P{sub 12}) which leave cavities of coordination numbers 16 and 15 for the rare earth atoms. - Graphical Abstract: The intergrowth structure La{sub 5}Ir{sub 19}P{sub 12}. Highlights: > Metal flux syntheses of intermetallic compounds. > Synthesis and structure of new phosphides RE{sub 5}Ir{sub 19}P{sub 12}. > Crystal chemistry of metal-rich phosphides. > Description of the RE{sub 5}Ir{sub 19}P{sub 12} structure as an intergrowth variant.

  11. Cross sections for (n, 2n), (n, p) and (n, ) reactions on osmium isotopes in the neutron energy range of 13.5-14.8 MeV.

    PubMed

    Zhao, Liangyong; Yuan, Jilong; Tuo, Fei; Zhang, Yanbin; Kong, Xiangzhong; Liu, Rong; Jiang, Li

    2008-10-01

    Cross sections for (n, 2n), (n, p) and (n, alpha) reactions on the osmium isotopes were measured in the neutron energies 13.5-14.8 MeV by the activation technique with the monitor reaction (93)Nb(n, 2n)(92 m)Nb. Our measurements were carried out by gamma-detection using a coaxial high-purity germanium (HPGe) detector. Natural high-purity osmium powder (99.9%) was fabricated as the samples. The neutron energies were determined by the cross-section ratios for (93)Nb(n, 2n)(92 m)Nb and (90)Zr(n, 2n)(89 m+g)Zr reactions. The fast neutrons were produced by the T(d, n)(4)He reaction. The results obtained were compared with previous data. PMID:18468910

  12. Defect Analysis of Boron Phosphide Thin Films and Sapphire Single Crystal Using Synchrotron X-ray Topography

    NASA Astrophysics Data System (ADS)

    Ding, Zihao

    Boron phosphide is an ideal semiconductor material used for neutron detectors because of its superior material properties, such as wide band gap and large thermal neutron capture cross-section of 10B. Since bulk BP is not readily available for neutron detector application, BP thin films are mainly synthesized by chemical vapor deposition (CVD). Among all the feasible substrates for BP deposition, SiC stands out due to its small lattice mismatch (4.5%) with BP, however it is necessary to optimize the growth condition to synthesize high quality BP thin films on SiC. In chapter III, BP thin film samples deposited on 4H-SiC and 6H-SiC under different growth conditions are characterized, mainly using synchrotron X-ray topography and other techniques such as optical microscopy and scanning electron microscopy. The relationship between BP thin film crystal quality and substrate material and orientation and other growth conditions is investigated. It can be concluded from the experimental data that the crystal quality of BP thin films on 4H-SiC substrate is much better than that on 6H-SiC substrate. Besides, poor crystalline quality of substrate will likely degrade the crystalline quality of epitaxial thin films. Sapphire single crystal has been widely used in high-technology industry because of its excellent combination between optical, electrical and mechanical properties. In this thesis, a-plane sapphire ribbon grown by Edge-defined Film-fed Growth method (EFG) is analyzed by characterizing the seed crystals used and the quality of as-grown ribbon, by reflection X-ray topography. Distributions and formation mechanisms of defects inside both the sapphire seed crystal and ribbon crystal are studied. Transmission topographs reveal the presence of two sets of slip bands that are nucleated from either edge, the distribution of which is symmetric in the used seed crystal and asymmetric in the pristine seed crystal. This phenomenon could be caused by the unstable growth

  13. Polarizability evolution on natural and artificial low dimensional binary semiconductor systems: A case study of stoichiometric aluminum phosphide semiconductor clusters.

    PubMed

    Karamanis, Panaghiotis; Xenides, Demetrios; Leszczynski, Jerzy

    2008-09-01

    The dependences of the static dipole polarizabilities per atom (PPAs) on the bonding and shape of selected stoichiometric aluminum phosphide clusters (ground states and higher lying species) of small and medium sizes have been comprehensively studied at Hartree-Fock and the second order Moller-Plesset perturbation levels of theory. It is shown that the nonmonotonic size variations in the mean PPAs of AlP species which maintain closed cagelike structures, frequently observed in clusters, are directly related to covalent homoatomic bonds inside each cluster's framework. Accordingly, the PPAs of clusters which are characterized by one or more bonds between the Al and P atoms are larger than the PPAs of clusters with the uniform alternating Al-P bond matrix. This is caused by the electron transfer increase from the electropositive Al to the electronegative P atom with the cluster growth. This transfer is larger for the clusters characterized by alternating Al-P bonding. The later effect explains the decrease in the PPA of AlP species which maintain closed cage-like structures, with the cluster growth. However, this picture drastically changes for artificial metastable prolate species built up by the ground states of smaller clusters. It is demonstrated that for prolate binary AlP clusters of medium size, the shape dominates against any other structural or bonding factor, forcing the PPA to increase with the cluster size. Nonetheless, as the cluster size grows, it is predicted that the PPAs of the studied prolate clusters will saturate eventually with the cluster size. Also, it is verified that the theoretical predicted polarizabilities of AlP semiconductor clusters are larger than the bulk polarizability in accord with other theoretical predictions for similar systems. Lastly, it is pointed out that major bonding or structural changes should take place in order the convergence with the bulk polarizability to be accomplished since it is revealed that the size increase

  14. Hessian Fly (Diptera: Cecidomyiidae) Mortality in Export Bale Compressors and Response to a Hydrogen Phosphide and Carbon Dioxide Gas Mixture.

    PubMed

    Yokoyama, Victoria Y; Cambron, Sue E; Muhareb, Jeannette

    2015-02-01

    Hessian fly, Mayetiola destructor (Say), puparial mortality was evaluated in three modern hay compressors that produce compressed standard and large-size bales for export to Asia-Pacific countries. Pressure on bales ranged from 93.4 to 139.4 kg/cm2, causing 90.0-99.9% mortality of 10,891-23,164 puparia. Puparial response to a cylinderized hydrogen phosphide (1.8-2%) and carbon dioxide (97.8-98%) gas mixture was evaluated as a potential quarantine treatment using 2-4 d-exposures to low, medium, and high doses of 0.73-0.86, 1.05-1.26, and 1.39-1.56 mg/liter, and temperatures of 5.87±1.14, 9.84±0.05, 16.14±0.14, and 20.35±0.11°C. Accumulative concentration multiplied by time products (mg h/liter) at all fumigation temperatures for low, medium, and high fumigant doses were 34.9-37.7, 52.2-54.3, and 67.9-73.1 for 2 d; 52.7-60.6, 77.9-89.2, and 102.1-110.7 for 3 d; and 69.9-82.0, 99.4-118.2, and 132.3-146.8 for 4 d, respectively. An increase in mortality was significantly related to an increase in fumigation duration at 5, 10, and 15°C, and an increase in fumigant dose at 10 and 15°C. Puparial mortality ranged from 97.2 to 100% at all doses and durations at 20°C with no survivors at the highest dose for 3 d and the mid- and highest dose for 4 d. Bale compression is currently used in the first phase of a multiple quarantine treatment to control potential Hessian fly contaminants in exported hay. The novel fumigant may have application as a single quarantine treatment for noncompressed, standard exported bales. PMID:26470109

  15. 16 CFR 23.7 - Misuse of the words “platinum,” “iridium,” “palladium,” “ruthenium,” “rhodium,” and “osmium.”

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... § 23.7 Misuse of the words “platinum,” “iridium,” “palladium,” “ruthenium,” “rhodium,” and “osmium.” (a) It is unfair or deceptive to use the words “platinum,” “iridium,” “palladium,” “ruthenium,” “rhodium... marking or description misrepresents the product's true composition. The Platinum Group Metals (PGM)...

  16. 16 CFR 23.7 - Misuse of the words “platinum,” “iridium,” “palladium,” “ruthenium,” “rhodium,” and “osmium.”

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... § 23.7 Misuse of the words “platinum,” “iridium,” “palladium,” “ruthenium,” “rhodium,” and “osmium.” (a) It is unfair or deceptive to use the words “platinum,” “iridium,” “palladium,” “ruthenium,” “rhodium... marking or description misrepresents the product's true composition. The Platinum Group Metals (PGM)...

  17. 16 CFR 23.7 - Misuse of the words “platinum,” “iridium,” “palladium,” “ruthenium,” “rhodium,” and “osmium.”

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... § 23.7 Misuse of the words “platinum,” “iridium,” “palladium,” “ruthenium,” “rhodium,” and “osmium.” (a) It is unfair or deceptive to use the words “platinum,” “iridium,” “palladium,” “ruthenium,” “rhodium... marking or description misrepresents the product's true composition. The Platinum Group Metals (PGM)...

  18. 16 CFR 23.7 - Misuse of the words “platinum,” “iridium,” “palladium,” “ruthenium,” “rhodium,” and “osmium.”

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... § 23.7 Misuse of the words “platinum,” “iridium,” “palladium,” “ruthenium,” “rhodium,” and “osmium.” (a) It is unfair or deceptive to use the words “platinum,” “iridium,” “palladium,” “ruthenium,” “rhodium... marking or description misrepresents the product's true composition. The Platinum Group Metals (PGM)...

  19. 16 CFR 23.7 - Misuse of the words “platinum,” “iridium,” “palladium,” “ruthenium,” “rhodium,” and “osmium.”

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... § 23.7 Misuse of the words “platinum,” “iridium,” “palladium,” “ruthenium,” “rhodium,” and “osmium.” (a) It is unfair or deceptive to use the words “platinum,” “iridium,” “palladium,” “ruthenium,” “rhodium... marking or description misrepresents the product's true composition. The Platinum Group Metals (PGM)...

  20. Metal–Arene Complexes with Indolo[3,2-c]-quinolines: Effects of Ruthenium vs Osmium and Modifications of the Lactam Unit on Intermolecular Interactions, Anticancer Activity, Cell Cycle, and Cellular Accumulation

    PubMed Central

    2013-01-01

    Six novel ruthenium(II)– and osmium(II)–arene complexes with three modified indolo[3,2-c]quinolines have been synthesized in situ starting from 2-aminoindoloquinolines and 2-pyridinecarboxaldehyde in the presence of [M(p-cymene)Cl2]2 (M = Ru, Os) in ethanol. All complexes have been characterized by elemental analysis, spectroscopic techniques (1H, 13C NMR, IR, UV–vis), and ESI mass spectrometry, while four complexes were investigated by X-ray diffraction. The complexes have been tested for antiproliferative activity in vitro in A549 (non-small cell lung), SW480 (colon), and CH1 (ovarian) human cancer cell lines and showed IC50 values between 1.3 and >80 μM. The effects of Ru vs Os and modifications of the lactam unit on intermolecular interactions, antiproliferative activity, and cell cycle are reported. One ruthenium complex and its osmium analogue have been studied for anticancer activity in vivo applied both intraperitoneally and orally against the murine colon carcinoma model CT-26. Interestingly, the osmium(II) complex displayed significant growth-inhibitory activity in contrast to its ruthenium counterpart, providing stimuli for further investigation of this class of compounds as potential antitumor drugs. PMID:23431223

  1. Re-Os in FeNi, Sulfide, and Phosphide: The Possible Determination of Internal Isochrons for Iron Meteorites

    NASA Astrophysics Data System (ADS)

    Papanastassiou, D. A.; Shen, J. J.; Wasserburg, G. J.

    1995-09-01

    For age determinations of specific events in the evolution of iron meteorites it is essential to obtain a reasonable range of physical-chemical fractionation of Re/Os. The possible stages of iron meteorite evolution which can, in principle, result in Re-Os fractionation include: a) condensation of PGE and of FeNi in the solar nebula; b) subsequent oxidation of part of the Fe by reaction with S; c) segregation and partial removal of massive FeS during melting on parent planetesimals; d) melting followed by fractional crystallization of the metal phase and crystallization of the remaining FeS; e) element redistribution during subsolidus phase transformations to produce schreibersite sheaves and finally precipitation or exsolution of minor micro-phases, e.g., rhabdite, at a later stage. Using negative ion, thermal ionization, we have determined the Re and Os concentrations and Os isotopic compositions in metal samples of iron meteorites. We have also analyzed metal-FeS pairs from two IA iron meteorites and a metal-phosphide pair from one IIIA iron. The analytical results for the paired analyses are shown in Table 1. The Re, Os partition coefficients between these coexisting phases are shown in Table 2. The whole-rock, metal samples for group IA, IIA, IIIA, IVA and IVB irons are consistent with a single, well-defined best fit line which yields a slope of 0.07863+/-0.00031 (corresponding to an age of 4.62+/-0.02 AE;lambda=1.64x10^(-11) a^(-1)) and an initial ^(187)Os/^(188)Os = 0.09560+/-0.00018 (all uncertainties are 2 sigma). There is also a suggestion from the data for the IIA and IVA groups of a difference in ages of 60+/-45 m.y. We find that, in the presence of the metal phase, neither Re nor Os enter into the sulphide. Therefore, the production or segregation of sulphide [e.g., under steps (b) and (c), above] act only as diluents for the Re and Os concentrations and can have no influence on the Re-Os isotope systematics and age determinations. Given the refractory

  2. Effect of the piperazine unit and metal-binding site position on the solubility and anti-proliferative activity of ruthenium(II)- and osmium(II)- arene complexes of isomeric indolo[3,2-c]quinoline-piperazine hybrids.

    PubMed

    Filak, Lukas K; Kalinowski, Danuta S; Bauer, Theresa J; Richardson, Des R; Arion, Vladimir B

    2014-07-01

    In this study, the indoloquinoline backbone and piperazine were combined to prepare indoloquinoline-piperazine hybrids and their ruthenium- and osmium-arene complexes in an effort to generate novel antitumor agents with improved aqueous solubility. In addition, the position of the metal-binding unit was varied, and the effect of these structural alterations on the aqueous solubility and antiproliferative activity of their ruthenium- and osmium-arene complexes was studied. The indoloquinoline-piperazine hybrids L(1-3) were prepared in situ and isolated as six ruthenium and osmium complexes [(η(6)-p-cymene)M(L(1-3))Cl]Cl, where L(1) = 6-(4-methylpiperazin-1-yl)-N-(pyridin-2-yl-methylene)-11H-indolo[3,2-c]quinolin-2-N-amine, M = Ru ([1a]Cl), Os ([1b]Cl), L(2) = 6-(4-methylpiperazin-1-yl)-N-(pyridin-2-yl-methylene)-11H-indolo[3,2-c]quinolin-4-N-amine, M = Ru ([2a]Cl), Os ([2b]Cl), L(3) = 6-(4-methylpiperazin-1-yl)-N-(pyridin-2-yl-methylene)-11H-indolo[3,2-c]quinolin-8-N-amine, M = Ru ([3a]Cl), Os ([3b]Cl). The compounds were characterized by elemental analysis, one- and two-dimensional NMR spectroscopy, ESI mass spectrometry, IR and UV-vis spectroscopy, and single-crystal X-ray diffraction. The antiproliferative activity of the isomeric ruthenium and osmium complexes [1a,b]Cl-[3a,b]Cl was examined in vitro and showed the importance of the position of the metal-binding site for their cytotoxicity. Those complexes containing the metal-binding site located at the position 4 of the indoloquinoline scaffold ([2a]Cl and [2b]Cl) demonstrated the most potent antiproliferative activity. The results provide important insight into the structure-activity relationships of ruthenium- and osmium-arene complexes with indoloquinoline-piperazine hybrid ligands. These studies can be further utilized for the design and development of more potent chemotherapeutic agents. PMID:24927493

  3. Effect of the Piperazine Unit and Metal-Binding Site Position on the Solubility and Anti-Proliferative Activity of Ruthenium(II)- and Osmium(II)- Arene Complexes of Isomeric Indolo[3,2-c]quinoline—Piperazine Hybrids

    PubMed Central

    2014-01-01

    In this study, the indoloquinoline backbone and piperazine were combined to prepare indoloquinoline–piperazine hybrids and their ruthenium- and osmium-arene complexes in an effort to generate novel antitumor agents with improved aqueous solubility. In addition, the position of the metal-binding unit was varied, and the effect of these structural alterations on the aqueous solubility and antiproliferative activity of their ruthenium- and osmium-arene complexes was studied. The indoloquinoline–piperazine hybrids L1–3 were prepared in situ and isolated as six ruthenium and osmium complexes [(η6-p-cymene)M(L1–3)Cl]Cl, where L1 = 6-(4-methylpiperazin-1-yl)-N-(pyridin-2-yl-methylene)-11H-indolo[3,2-c]quinolin-2-N-amine, M = Ru ([1a]Cl), Os ([1b]Cl), L2 = 6-(4-methylpiperazin-1-yl)-N-(pyridin-2-yl-methylene)-11H-indolo[3,2-c]quinolin-4-N-amine, M = Ru ([2a]Cl), Os ([2b]Cl), L3 = 6-(4-methylpiperazin-1-yl)-N-(pyridin-2-yl-methylene)-11H-indolo[3,2-c]quinolin-8-N-amine, M = Ru ([3a]Cl), Os ([3b]Cl). The compounds were characterized by elemental analysis, one- and two-dimensional NMR spectroscopy, ESI mass spectrometry, IR and UV–vis spectroscopy, and single-crystal X-ray diffraction. The antiproliferative activity of the isomeric ruthenium and osmium complexes [1a,b]Cl–[3a,b]Cl was examined in vitro and showed the importance of the position of the metal-binding site for their cytotoxicity. Those complexes containing the metal-binding site located at the position 4 of the indoloquinoline scaffold ([2a]Cl and [2b]Cl) demonstrated the most potent antiproliferative activity. The results provide important insight into the structure–activity relationships of ruthenium- and osmium-arene complexes with indoloquinoline–piperazine hybrid ligands. These studies can be further utilized for the design and development of more potent chemotherapeutic agents. PMID:24927493

  4. Reactivity of nitrido complexes of ruthenium(VI), osmium(VI), and manganese(V) bearing Schiff base and simple anionic ligands.

    PubMed

    Man, Wai-Lun; Lam, William W Y; Lau, Tai-Chu

    2014-02-18

    Nitrido complexes (M≡N) may be key intermediates in chemical and biological nitrogen fixation and serve as useful reagents for nitrogenation of organic compounds. Osmium(VI) nitrido complexes bearing 2,2':6',2″-terpyridine (terpy), 2,2'-bipyridine (bpy), or hydrotris(1-pyrazolyl)borate anion (Tp) ligands are highly electrophilic: they can react with a variety of nucleophiles to generate novel osmium(IV)/(V) complexes. This Account describes our recent results studying the reactivity of nitridocomplexes of ruthenium(VI), osmium(VI), and manganese(V) that bear Schiff bases and other simple anionic ligands. We demonstrate that these nitrido complexes exhibit rich chemical reactivity. They react with various nucleophiles, activate C-H bonds, undergo N···N coupling, catalyze the oxidation of organic compounds, and show anticancer activities. Ruthenium(VI) nitrido complexes bearing Schiff base ligands, such as [Ru(VI)(N)(salchda)(CH3OH)](+) (salchda = N,N'-bis(salicylidene)o-cyclohexyldiamine dianion), are highly electrophilic. This complex reacts readily at ambient conditions with a variety of nucleophiles at rates that are much faster than similar reactions using Os(VI)≡N. This complex also carries out unique reactions, including the direct aziridination of alkenes, C-H bond activation of alkanes and C-N bond cleavage of anilines. The addition of ligands such as pyridine can enhance the reactivity of [Ru(VI)(N)(salchda)(CH3OH)](+). Therefore researchers can tune the reactivity of Ru≡N by adding a ligand L trans to nitride: L-Ru≡N. Moreover, the addition of various nucleophiles (Nu) to Ru(VI)≡N initially generate the ruthenium(IV) imido species Ru(IV)-N(Nu), a new class of hydrogen-atom transfer (HAT) reagents. Nucleophiles also readily add to coordinated Schiff base ligands in Os(VI)≡N and Ru(VI)≡N complexes. These additions are often stereospecific, suggesting that the nitrido ligand has a directing effect on the incoming nucleophile. M≡N is also

  5. Aspects of the cleavage of phosphines with potassium: Synthesis and reactivity of lithium and potassium bis(p-(dimethylamino)phenyl)phosphide

    SciTech Connect

    Toth, I.; Hanson, B.E.; Davis, M.E. )

    1990-03-01

    The cleavage of the triarylphosphines P(p-C{sub 6}H{sub 4}NMe{sub 2}){sub 3} and PhP(p-C{sub 6}H{sub 4}NMe{sub 2}){sub 2} with potassium in ether solvents was found to occur at room temperature. Cleavage of the mixed phosphine PhP(p-C{sub 6}H{sub 4}NMe{sub 2}){sub 2} was found to give a mixture of products that reflects the relative stability of the phosphides KP(Ph)(p-C{sub 6}H{sub 4}NMe{sub 2}) and KP(p-C{sub 6}H{sub 4}NMe{sub 2}){sub 2}. Cleavage with lithium resulted in the scrambling of the aryl groups so that the products LiPPh{sub 2} and P(Ph){sub 2}(p-C{sub 6}H{sub 4}NMe{sub 2}) also were obtained.

  6. Results from Coupled Optical and Electrical Sentaurus TCAD Models of a Gallium Phosphide on Silicon Electron Carrier Selective Contact Solar Cell

    SciTech Connect

    Limpert, Steven; Ghosh, Kunal; Wagner, Hannes; Bowden, Stuart; Honsberg, Christiana; Goodnick, Stephen; Bremner, Stephen; Green, Martin

    2014-06-09

    We report results from coupled optical and electrical Sentaurus TCAD models of a gallium phosphide (GaP) on silicon electron carrier selective contact (CSC) solar cell. Detailed analyses of current and voltage performance are presented for devices having substrate thicknesses of 10 μm, 50 μm, 100 μm and 150 μm, and with GaP/Si interfacial quality ranging from very poor to excellent. Ultimate potential performance was investigated using optical absorption profiles consistent with light trapping schemes of random pyramids with attached and detached rear reflector, and planar with an attached rear reflector. Results indicate Auger-limited open-circuit voltages up to 787 mV and efficiencies up to 26.7% may be possible for front-contacted devices.

  7. A theoretical comparison of the near-optimum design and predicted performance of n/p and p/n indium phosphide homojunction solar cells

    NASA Technical Reports Server (NTRS)

    Goradia, Chandra; Thesling, William; Weinberg, Irving

    1991-01-01

    Using a detailed simulation model of p(+)nn(+) and n(+)pp(+) indium phosphide (InP) homojunction solar cells, extensive parametric variation computer simulation runs were performed to aid in making near-optimum designs for these two solar cell configurations. The values of all the geometrical and material parameters corresponding to the near-optimal designs of both these configurations are presented. The results of parametric variation runs are presented for each configuration showing how the performance parameters J(sub sc), V(sub oc), and eta vary with each of the cell design parameters for the near-optimally designed cell. Finally, the theoretically obtained results are discussed, and the relative merits and drawbacks of the two configurations are compared.

  8. Arene-metal-carborane triple-decker sandwiches. Designed synthesis of homo- and heterobimetallic complexes of cobalt, iron, ruthenium, and osmium

    SciTech Connect

    Davis, J.H. Jr.; Sinn, E.; Grimes, R.N. )

    1989-06-21

    This paper describes the systematic preparation and characterization of new families of triple-decker sandwich complexes incorporating formal cyclo-Et{sub 2}C{sub 2}B{sub 3}H{sub 3}{sup 4{minus}} bridging ligands, including the first species of this class containing second- or third-row transition metals. Complexes of general formula (L)M(Et{sub 2}C{sub 2}B{sub 3}H{sub 3})M{prime}(L) (M = Ru, Os; M{prime} = Co, Ru; L = cymene (p-isopropyltoluene), Cp, or C{sub 5}Me{sub 5}) were obtained in stepwise fashion via (1) synthesis of closo-(L)M(Et{sub 2}C{sub 2}B{sub 4}H{sub 4}) metallacarboranes, (2) decapitation (apex BH removal) of these complexes to give nido-(L)M(Et{sub 2}C{sub 2}B{sub 3}H{sub 5}), (3) bridge deprotonation to form the corresponding mono- or dianion, and (4) reaction of the anion with an arene metal halide to generate the desired triple-decker compound. In addition, the cobalt-iron triple-decker CpCo(Et{sub 2}C{sub 2}B{sub 3}H{sub 3})FeCp was prepared via treatment of ({eta}{sup 6}-C{sub 8}H{sub 10})Fe(Et{sub 2}C{sub 2}B{sub 3}H{sub 4}){sup {minus}} with Na{sup +}Cp{sup {minus}} and CoCl{sub 2} followed by air oxidation. The reaction of (CO){sub 3}RuCl{sub 2} with (C{sub 5}me{sub 5})Co(Et{sub 2}C{sub 2}B{sub 3}H{sub 3}){sup 2{minus}} gave the pseudo-triple-decker complex (C{sub 5}Me{sub 5})Co(Et{sub 2}C{sub 2}B{sub 3}H{sub 3})Ru(CO){sub 3}. The triple-deckers, especially those containing osmium, are susceptible to chlorination by RuCl{sub 3}, OsCl{sub 3}, or dichloromethane, forming exclusively the 4-chloro derivatives. All of the characterized triple-decker complexes are air-stable crystalline solids (except for the osmium-ruthenium species, which are air sensitive) and have been structurally characterized from their {sup 11}B and {sup 1}H NMR, infrared, visible-UV, and unit- and high-resolution mass spectra.

  9. A potential link between magmatic volatiles and mantle source lithology in the Hawaiian Plume: a view from olivine-hosted melt inclusions and osmium isotopes

    NASA Astrophysics Data System (ADS)

    Marske, J. P.; Hauri, E. H.; Garcia, M. O.; Pietruszka, A. J.

    2013-12-01

    Variations in radiogenic isotope ratios and magmatic volatile abundances (e.g., CO2 or H2O) in lavas from Hawaiian volcanoes reveal important magmatic processes (e.g., melting of a heterogeneous source and magma degassing). Based on variations in ratios of highly incompatible trace elements (e.g., Nb/La) and radiogenic isotopes (e.g., 206Pb/204Pb), shield-stage Hawaiian lavas likely originate from a plume source containing peridotite and ancient recycled oceanic crust (pyroxenite). The source region may also be heterogeneous with respect to volatile concentrations. However, shallow magma degassing makes it difficult to determine if there is a link between mantle source composition and the volatile budget. We analyzed osmium isotopic ratios and volatile contents in olivines and glasses for 34 samples from Koolau, Mauna Kea, Mauna Loa, Hualalai, Kilauea, and Loihi to determine if volatiles in magmas correlate with geochemical tracers of source lithology. For a given volcano, most 187Os/188Os values of olivines (0.127-0.134) are similar to the whole-rock values, yet some Mauna Loa and Loihi olivines display the lower ratios (0.116-0.118) that may reflect partial melts of ancient recycled mantle lithosphere. SIMS analyses of Hawaiian glasses reveal a range in abundances of CO2 (10-250 ppm), H2O (0.2-1.2 wt.%), S (38-2960 ppm), and Cl (39-2960 ppm). However, most samples have low CO2 contents (<100 ppm) indicating that the lavas are degassed. Olivine-hosted melt inclusions from the same Hawaiian samples display a wider range of volatile abundances (i.e. 10-760 ppm CO2) than matrix glasses that may reflect mixing of undegassed to moderately degassed magmas. The average CO2 and H2O/CO2 contents in the least degassed olivine-hosted melt inclusions (with >200 ppm CO2) display a broad correlation with the osmium isotopic compositions of the olivines. This indicates a potential link between pre-eruptive volatile budgets and mantle sources lithology may exist within the

  10. Growth of Zinc Phosphide (Zn3P2) and Iron Disulfide (FeS2) using pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Vaddi, Rajesh

    The growing energy needs of society have triggered tremendous interest in the development of photovoltaics formed from earth abundant materials. Zinc Phosphide (Zn3P2) and Iron Pyrite (FeS2) are two materials formed from elements with large Earth crustal abundances that have nearly ideal band gap energies (1.5eV and 0.96 eV, respectively) and optical absorption coefficients (~104 /cm) for use as absorber layers in solar cells. In this work, the structural, optical, and electronic properties of these materials produced in thin film form using pulsed laser deposition have been explored. Stoichiometric Zn3P2 thin films were obtained at a laser energy density of 3 J/cm2. However, these films were found to be amorphous. Crystallization of these highly resistive amorphous thin films was possible after rapid thermal annealing (RTA). A near optimal band gap of 1.6 eV and a high absorption coefficient of >104/cm were observed for samples annealed at 500 C for 60 seconds when high ramp rates of 150 °C/sec were used for annealing. XPS studies showed the presence of a trace amount of oxygen in the samples upon depth profiling. Schottky barrier heights were extracted for samples annealed at 350 °C and 500 °C with different metals. Al and Mg showed higher barrier heights with good diode rectification behavior. Fermi level pinning was shown to be a significant concern in both cases due to the large values of interface states observed (> 1013/cm2-eV). A Schottky barrier solar cell was fabricated using these films and showed low efficiency with a low Voc of 410 mV that was impacted by Fermi level pinning. Growth of Iron pyrite thin films from an FeS target was demonstrated for the first time using pulsed laser deposition. For the different laser energy densities and substrate temperatures explored, amorphous FeS (Pyrrhotite) was mainly produced. Conversion of FeS to FeS2 was obtained by sulfurization of thin films at 350 °C for times of 30 minutes at a N2 flow rates of 200

  11. Reversible Redox-Based Optical Sensing of Parts per Million Levels of Nitrosyl Cation in Organic Solvents by Osmium Chromophore-Based Monolayers

    SciTech Connect

    Gupta,T.; Cohen, R.; Evmenenko, G.; Dutta, P.; van der Boom, M.

    2007-01-01

    Exposure of an osmium(II)-based monolayer on glass to organic solvents containing 0.36-116 ppm of NOBF{sub 4} results in one-electron transfer from the covalently immobilized complexes to the inorganic analyte with concurrent optical changes. The NO{sup +} induced oxidation of the monolayer can be detected optically with an off-the-self-UV/vis spectrophotometer (260-800 nm). The redox-based NO{sup +} detection and quantification system can be reset with water within {approx}20 s for at least 40 times. The reaction of the monolayer with a THF solution containing 5 ppm of NOBF{sub 4} follows pseudo first-order kinetics in the monolayer with {Delta}G{sup {double_dagger}}{sub 298K} = 21.5 {+-} 0.7 kcal/mol, {Delta}H{sup {double_dagger}} = 9.5 {+-} 0.3 kcal/mol, and {Delta}S{sup {double_dagger}} = -40.6 {+-} 1.1 eu. The monolayer structure and properties have been resolved by electrochemical measurements and synchrotron X-ray reflectivity measurements in combination with density functional theory calculations (B3LYP/SDD level of theory).

  12. Three-dimensional shape of the Golgi apparatus in different cell types: serial section scanning electron microscopy of the osmium-impregnated Golgi apparatus.

    PubMed

    Koga, Daisuke; Kusumi, Satoshi; Ushiki, Tatsuo

    2016-04-01

    Although many studies of the Golgi apparatus structure have been performed by light and electron microscopy, the full shape of the Golgi apparatus remained unclear due to the technical limitations of the previously applied microscopy techniques. In this study, we used serial section scanning electron microscopy (SEM) for the morphological study of the Golgi apparatus. This method is useful for three-dimensional (3D) reconstruction of cellular structures without requiring specialized instruments, unlike focused ion beam SEM (FIB-SEM) and serial block face SEM (SBF-SEM). Using the serial section SEM method developed by our laboratory, we investigate the 3D shape of the osmium-impregnated Golgi apparatus in rat epididymal cells, pancreatic acinar cells and gonadotropes. The combination of serial section SEM and a 3D reconstruction technique enabled us to elucidate the entire shape of the Golgi apparatus in these cells. The full shape of the Golgi apparatus in epididymal cells formed a basket-like structure with oval-shaped cisterns, while the Golgi apparatus in an acinar cell from the pancreas was composed of elongated ribbon-like structures that were connected to each other, making a coarse network. The overall image of the Golgi apparatus cisterns from a gonadotrope looked like a spherical cage. This study has clearly shown that entire 3D shape of the Golgi apparatus varies depending on the cell type and that the Golgi cisterns network appears as a single mass located in the large region of the cytoplasm. PMID:26609075

  13. Ruthenium- and osmium-arene complexes of 8-substituted indolo[3,2-c]quinolines: Synthesis, X-ray diffraction structures, spectroscopic properties, and antiproliferative activity

    PubMed Central

    Filak, Lukas K.; Göschl, Simone; Hackl, Stefanie; Jakupec, Michael A.; Arion, Vladimir B.

    2012-01-01

    Six novel ruthenium(II)- and osmium(II)-arene complexes with indoloquinoline modified ligands containing methyl and halo substituents in position 8 of the molecule backbone have been synthesised and comprehensively characterised by spectroscopic methods (1H, 13C NMR, UV–Vis), ESI mass spectrometry and X-ray crystallography. Binding of indoloquinolines to a metal-arene scaffold makes the products soluble enough in biological media to allow for assaying their antiproliferative activity. The complexes were tested in three human cancer cell lines, namely A549 (non-small cell lung cancer), SW480 (colon carcinoma) and CH1 (ovarian carcinoma), yielding IC50 values in the 10−6–10−7 M concentration range after continuous exposure for 96 h. Compounds with halo substituents in position 8 are more effective cytotoxic agents in vitro than the previously reported species halogenated in position 2 of the indoloquinoline backbone. High antiproliferative activity of both series of substances may be due at least in part to their potential to act as DNA intercalators. PMID:23471093

  14. Layer-by-layer self-assembled osmium polymer-mediated laccase oxygen cathodes for biofuel cells: the role of hydrogen peroxide.

    PubMed

    Scodeller, Pablo; Carballo, Romina; Szamocki, Rafael; Levin, Laura; Forchiassin, Flavia; Calvo, Ernesto J

    2010-08-18

    High potential purified Trametes trogii laccase has been studied as a biocatalyst for oxygen cathodes composed of layer-by-layer self-assembled thin films by sequential immersion of mercaptopropane sulfonate-modified Au electrode surfaces in solutions containing laccase and osmium-complex bound to poly(allylamine), (PAH-Os). The polycation backbone carries the Os redox relay, and the polyanion is the enzyme adsorbed from a solution of a suitable pH so that the protein carries a net negative charge. Enzyme thin films were characterized by quartz crystal microbalance, ellipsometry, cyclic voltammetry, and oxygen reduction electrocatalysis under variable oxygen partial pressures with a rotating disk electrode. New kinetic evidence relevant to biofuel cells is presented on the detection of traces of H(2)O(2), intermediate in the O(2) reduction, with scanning electrochemical microscopy (SECM). Furthermore the inhibitory effect of peroxide on the biocatalytic current resulted in abnormal current dependence on the O(2) partial pressure and peak shape with hysteresis in the polarization curves under stagnant conditions, which is offset upon stirring with the RDE. The new kinetic evidence reported in the present work is very relevant for the operation of biofuel cells under stagnant conditions of O(2) mass transport. PMID:20698679

  15. The Rare Earth Osmium Carbides Ln5Os 3C 4- x( Ln=La-Nd, Sm) with a New Type of Filled Mn 3Si 3Structure

    NASA Astrophysics Data System (ADS)

    Wachtmann, Klaus H.; Hüfken, Thomas; Jeitschko, Wolfgang

    1997-06-01

    The five compoundsLn5Os3C4-x(Ln=La-Nd, Sm) have been prepared by arc-melting cold-pressed pellets of the elemental components and subsequent annealing. They crystallize with a new hexagonal structure type (P63/mcm,Z=2), which has been determined from single-crystal X-ray data ofLn5Os3C3.25(4)(a=919.57(8) pm,c=673.86(4) pm,R=0.015 for 293 structure factors and 14 variable parameters) and also refined for Nd5Os3C3.17(7)(a=897.8(1) pm,c=667.42(9) pm,R=0.028, 440 F values, 14 variables). The metal positions correspond to the positions of the Mn5Si3structure. The carbon position of the Mo5Si3C1-xstructure is partially filled. The three additional carbon atoms of the formula La5Os3C4-xoccupy distorted octahedral La4Os2voids. The linear Os-C-Os units of these La4Os2C octahedra have Os-C bond lengths of 191 pm. They are linked via common osmium atoms, thus forming a new kind of zig-zag-shaped polyanion. Using oxidation numbers the compound may be rationalized with the formula (5La+3)+15(Os3C3)-14(0.25C-4)-1.

  16. Indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Weinberg, Irving

    1991-01-01

    The direction for InP solar cell research; reduction of cell cost; increase of cell efficiency; measurements needed to better understand cell performance; n/p versus p/n; radiation effects; major problems in cell contacting; and whether the present level of InP solar cell research in the USA should be maintained, decreased, or increased were considered.

  17. A major and trace element and strontium, neodymium, and osmium isotopic study of a thick pyroxenite layer from the Beni Bousera Ultramafic Complex of northern Morocco

    NASA Astrophysics Data System (ADS)

    Kumar, Niraj; Reisberg, Laurie; Zindler, Alan

    1996-04-01

    Major and trace element concentrations and strontium, neodymium, and osmium isotopic compositions were determined for a series of samples from a thick, symmetrically zoned pyroxenite layer from the Beni Bousera massif. The two main rock types included in the layer, garnet pyroxenites and websterites, have distinct, well-defined elemental and isotopic compositions. The websterites are, in most respects, more refractory than the garnet pyroxenites, but, surprisingly, are more enriched in the highly incompatible elements. The observed characteristics can be explained by formation of the layer by crystal deposition along a magma conduit at medium to high pressures, given that the source and composition of the magma varies with time. Re-Os model ages for three samples of different lithology converge to about 1.3 b.y., which is interpreted as the age of formation of the layer. In contrast, Sm-Nd model ages from the layer are mutually conflicting or indeterminate, largely due to the similarity between the measured neodymium isotopic ratios and that of the depleted mantle. On the other hand, the Sm-Nd model age obtained from an extremely depleted peridotite ( 143Nd/ 144Nd = 0.51391) located about 30 m from the layer falls within error of the Re-Os ages, providing support for an extensive magmatic event at about that time. This same age was obtained by several techniques from the closely related Ronda Ultramafic Complex of southern Spain. This may suggest that the mantle lithosphere currently exposed along the southern margin of Spain and the northern margin of Morocco has been linked for over a billion years.

  18. Multi-component nanoporous platinum-ruthenium-copper-osmium-iridium alloy with enhanced electrocatalytic activity towards methanol oxidation and oxygen reduction

    NASA Astrophysics Data System (ADS)

    Chen, Xiaoting; Si, Conghui; Gao, Yulai; Frenzel, Jan; Sun, Junzhe; Eggeler, Gunther; Zhang, Zhonghua

    2015-01-01

    Multi-component nanoporous platinum-ruthenium-copper-osmium-iridium (np-PtRuCuOsIr) electrocatalyst has been facilely fabricated by chemical dealloying of mechanically alloyed AlCuPtRuOsIr precursor. The np-PtRuCuOsIr catalyst exhibits a typical three-dimensional bi-continuous interpenetrating ligament/channel structure with a length scale of ∼2.5 nm. The np-PtRuCuOsIr catalyst reaches a higher level in the mass activity (857.5 mA mgPt-1) and specific activity (3.0 mA cm-2) towards methanol oxidation compared to the commercial PtC catalyst (229.5 mA mgPt-1 and 0.5 mA cm-2 respectively). Moreover, the CO stripping peak of np-PtRuCuOsIr is 0.54 V (vs. SCE), 130 mV negative shift in comparison with the commercial PtC (0.67 V vs. SCE). The half-wave potential of np-PtRuCuOsIr is 0.900 V vs. RHE, 36 mV positive compared with that of the commercial PtC (0.864 V vs. RHE). The np-PtRuCuOsIr catalyst also shows 1.8 and 3.8 times enhancement in the mass and specific activity towards oxygen reduction than the commercial PtC. Moreover, the np-PtRuCuOsIr alloy exhibits superior oxygen reduction activities even after 15 K cycles, indicating its excellent long-term stability. The present np-PtRuCuOsIr can act as a promising candidate for the electrocatalyst in direct methanol fuel cells (DMFCs).

  19. Ruthenium(II) and osmium(II) vinyl complexes as highly sensitive and selective chromogenic and fluorogenic probes for the sensing of carbon monoxide in air.

    PubMed

    Toscani, Anita; Marín-Hernández, Cristina; Moragues, María E; Sancenón, Félix; Dingwall, Paul; Brown, Neil J; Martínez-Máñez, Ramón; White, Andrew J P; Wilton-Ely, James D E T

    2015-10-01

    The detection of carbon monoxide in solution and air has been achieved using simple, inexpensive systems based on the vinyl complexes [M(CHCHR)Cl(CO)(BTD)(PPh3 )2 ] (R=aryl, BTD=2,1,3-benzothiadiazole). Depending on the nature of the vinyl group, chromogenic and fluorogenic responses signalled the presence of this odourless, tasteless, invisible, and toxic gas. Solutions of the complexes in CHCl3 underwent rapid change between easily differentiated colours when exposed to air samples containing CO. More significantly, the adsorption of the complexes on silica produced colorimetric probes for the naked-eye detection of CO in the gas phase. Structural data for key species before and after the addition of CO were obtained by means of single X-ray diffraction studies. In all cases, the ruthenium and osmium vinyl complexes studied showed a highly selective response to CO with exceptionally low detection limits. Naked-eye detection of CO at concentrations as low as 5 ppb in air was achieved with the onset of toxic levels (i.e., 100 ppm), thus resulting in a remarkably clear colour change. Moreover, complexes bearing pyrenyl, naphthyl, and phenanthrenyl moieties were fluorescent, and greater sensitivities were achieved (through turn-on emission fluorescence) in the presence of CO both in solution and air. This behaviour was explored computationally using time-dependent density functional theory (TDDFT) experiments. In addition, the systems were shown to be selective for CO over all other gases tested, including water vapour and common organic solvents. Supporting the metal complexes on cellulose strips for use in an existing optoelectronic device allows numerical readings for the CO concentration to be obtained and provision of an alarm system. PMID:26270512

  20. Luminescent osmium(ii) bi-1,2,3-triazol-4-yl complexes: photophysical characterisation and application in light-emitting electrochemical cells.

    PubMed

    Ross, Daniel A W; Scattergood, Paul A; Babaei, Azin; Pertegás, Antonio; Bolink, Henk J; Elliott, Paul I P

    2016-05-01

    The series of osmium(ii) complexes [Os(bpy)3-n(btz)n][PF6]2 (bpy = 2,2'-bipyridyl, btz = 1,1'-dibenzyl-4,4'-bi-1,2,3-triazolyl, n = 0, n = 1, n = 2, n = 3), have been prepared and characterised. The progressive replacement of bpy by btz leads to blue-shifted UV-visible electronic absorption spectra, indicative of btz perturbation of the successively destabilised bpy-centred LUMO. For , a dramatic blue-shift relative to the absorption profile for is observed, indicative of the much higher energy LUMO of the btz ligand over that of bpy, mirroring previously reported data on analogous ruthenium(ii) complexes. Unlike the previously reported ruthenium systems, heteroleptic complexes and display intense emission in the far-red/near-infrared (λmax = 724 and 713 nm respectively in aerated acetonitrile at RT) as a consequence of higher lying, and hence less thermally accessible, (3)MC states. This assertion is supported by ground state DFT calculations which show that the dσ* orbitals of to are destabilised by between 0.60 and 0.79 eV relative to their Ru(ii) analogues. The homoleptic complex appears to display extremely weak room temperature emission, but on cooling to 77 K the complex exhibits highly intense blue emission with λmax 444 nm. As complexes to display room temperature luminescent emission and readily reversible Os(ii)/(iii) redox couples, light-emitting electrochemical cell (LEC) devices were fabricated. All LECs display electroluminescent emission in the deep-red/near-IR (λmax = 695 to 730 nm). Whilst devices based on and show inferior current density and luminance than LECs based on , the device utilising shows the highest external quantum efficiency at 0.3%. PMID:27055067

  1. A pyrene-substituted tris(bipyridine)osmium(II) complex as a versatile redox probe for characterizing and functionalizing carbon nanotube- and graphene-based electrodes.

    PubMed

    Le Goff, Alan; Reuillard, Bertrand; Cosnier, Serge

    2013-07-01

    We report the functionalization of nanostructured graphene-based electrode with an original (bis(2,2'-bipyridine)(4,4'-bis(4-pyrenyl-1-ylbutyloxy)-2,2'-bipyridine]osmium(II) hexafluorophosphate complex bearing pyrene groups. Graphene oxide (GO) and chemically reduced graphene oxide (c-RGO) paper electrodes were prepared by the flow-directed filtration method. After film transfer via the soluble membrane technique, the homogeneous and stable GO electrode was electrochemically reduced in water to achieve electrochemically reduced graphene oxide (e-RGO) film on the electrode. The electrochemical properties of GO, c-RGO, and e-RGO electrodes were characterized by scanning electron microscopy and electrochemistry. Cyclic voltammetry of the Ru(NH3)6(2+/3+) redox probe underlines the important influence of the RGO preparation method on electrochemical properties. We finally achieved the flexible functionalization of graphene-based electrodes using either supramolecular binding of the Os(II) complex bearing pyrene groups or its electropolymerization via the irreversible oxidation of pyrene. The properties of these functionalized graphene paper electrodes were compared to glassy carbon (GC) and multiwalled carbon nanotube (MWCNT) electrodes. Thanks to its divalent binding sites, the Os(II) complex constitutes a useful tool to probe the π-extended graphitic surface of RGO and MWCNT films. The Os(II) complex interacts strongly via noncovalent π-π interactions, with π-extended graphene planes, thus acting as a marker to quantify the electroactive surface of both MWCNT and RGO electrodes and to illustrate their ease of functionalization. PMID:23767958

  2. Emissive osmium(II) complexes supported by N-heterocyclic carbene-based C^C^C-pincer ligands and aromatic diimines.

    PubMed

    Chung, Lai-Hon; Chan, Siu-Chung; Lee, Wing-Chun; Wong, Chun-Yuen

    2012-08-20

    Osmium(II) complexes containing N-heterocyclic carbene (NHC)-based pincer ligand 1,3-bis(1-methylimidazolin-2-ylidene)phenyl anion (C(1)^C^C(1)) or 1,3-bis(3-methylbenzimidazolin-2-ylidene)phenyl anion (C(2)^C^C(2)) and aromatic diimine (2,2'-bipyridine (bpy), 1,10-phenanthroline (phen), or 4,4'-diphenyl-2,2'-bipyridine (Ph(2)bpy)) in the form of [Os(C^C^C)(N^N)(CO)](+) have been prepared. Crystal structures for these complexes show that the Os-C(NHC) bonds are essentially single (Os-C(NHC) distances = 2.079(5)-2.103(7) Å). Spectroscopic comparisons and time-dependent density functional theory (TD-DFT) calculations suggest that the lowest-energy electronic transition associated with these complexes (λ(max) = 493-536 nm, ε(max) = (5-10) × 10(3) dm(3) mol(-1) cm(-1), solvent = CH(3)CN) originate from a d(π)(Os(II)) → π*(N^N) metal-to-ligand charge transfer transition, where the d(π)(Os(II)) and π*(N^N) levels contain significant contribution from the C^C^C ligands. All these complexes are emissive in the red-spectral region (674-731 nm) with quantum yields of 10(-4)-10(-2) and emission lifetimes of around 1-6 μs. Transient absorption spectroscopy and spectroelectrochemical measurements have also been used to probe the nature of the emissive excited-states. Overall, this joint experimental and theoretical investigation reveals that the C^C^C ligands can be used to modulate the photophysical properties of a [Os(N^N)] core via the formation of the hybrid [Os + C^C^C] frontier orbitals. PMID:22873818

  3. A Mechanistic Study of CO2 Reduction at the Interface of a Gallium Phosphide (GaP) Surface using Core-level Spectroscopy - Oral Presentation

    SciTech Connect

    Flynn, Kristen

    2015-08-19

    Carbon dioxide (CO2) emission into the atmosphere has increased tremendously through burning of fossil fuels, forestry, etc.. The increased concentration has made CO2 reductions very attractive though the reaction is considered uphill. Utilizing the sun as a potential energy source, CO2 has the possibility to undergo six electron and four proton transfers to produce methanol, a useable resource. This reaction has been shown to occur selectively in an aqueous pyridinium solution with a gallium phosphide (GaP) electrode. Though this reaction has a high faradaic efficiency, it was unclear as to what role the GaP surface played during the reaction. In this work, we aim to address the fundamental role of GaP during the catalytic conversion, by investigating the interaction between a clean GaP surface with the reactants, products, and intermediates of this reaction using X-ray photoelectron spectroscopy. We have determined a procedure to prepare atomically clean GaP and our initial CO2 adsorption studies have shown that there is evidence of chemisorption and reaction to form carbonate on the clean surface at LN2 temperatures (80K), in contrast to previous theoretical calculations. These findings will enable future studies on CO2 catalysis.

  4. Effect of multilayer structure, stacking order and external electric field on the electrical properties of few-layer boron-phosphide.

    PubMed

    Chen, Xianping; Tan, Chunjian; Yang, Qun; Meng, Ruishen; Liang, Qiuhua; Jiang, Junke; Sun, Xiang; Yang, D Q; Ren, Tianling

    2016-06-28

    Development of nanoelectronics requires two-dimensional (2D) systems with both direct-bandgap and tunable electronic properties as they act in response to the external electric field (E-field). Here, we present a detailed theoretical investigation to predict the effect of atomic structure, stacking order and external electric field on the electrical properties of few-layer boron-phosphide (BP). We demonstrate that the splitting of bands and bandgap of BP depends on the number of layers and the stacking order. The values for the bandgap show a monotonically decreasing relationship with increasing layer number. We also show that AB-stacking BP has a direct-bandgap, while ABA-stacking BP has an indirect-bandgap when the number of layers n > 2. In addition, for a bilayer and a trilayer, the bandgap increases (decreases) as the electric field increases along the positive direction of the external electric field (E-field) (negative direction). In the case of four-layer BP, the bandgap exhibits a nonlinearly decreasing behavior as the increase in the electric field is independent of the electric field direction. The tunable mechanism of the bandgap can be attributed to a giant Stark effect. Interestingly, the investigation also shows that a semiconductor-to-metal transition may occur for the four-layer case or more layers beyond the critical electric field. Our findings may inspire more efforts in fabricating new nanoelectronics devices based on few-layer BP. PMID:27250915

  5. A Mechanistic Study of CO2 Reduction at the Interface of a Gallium Phosphide (GaP) Surface using Core-level Spectroscopy

    SciTech Connect

    Flynn, Kristen

    2015-08-18

    Carbon dioxide (CO2) emission into the atmosphere has increased tremendously through burning of fossil fuels, forestry, etc.. The increased concentration has made CO2 reductions very attractive though the reaction is considered uphill. Utilizing the sun as a potential energy source, CO2 has the possibility to undergo six electron and four proton transfers to produce methanol, a useable resource. This reaction has been shown to occur selectively in an aqueous pyridinium solution with a gallium phosphide (GaP) electrode. Though this reaction has a high faradaic efficiency, it was unclear as to what role the GaP surface played during the reaction. In this work, we aim to address the fundamental role of GaP during the catalytic conversion, by investigating the interaction between a clean GaP surface with the reactants, products, and intermediates of this reaction using X-ray photoelectron spectroscopy. We have determined a procedure to prepare atomically clean GaP and our initial CO2 adsorption studies have shown that there is evidence of chemisorption and reaction to form carbonate on the clean surface at LN2 temperatures (80K), in contrast to previous theoretical calculations. These findings will enable future studies on CO2 catalysis.

  6. New Intermetallic Ternary Phosphide Chalcogenide AP2-xXx (A = Zr, Hf; X = S, Se) Superconductors with PbFCl-Type Crystal Structure

    NASA Astrophysics Data System (ADS)

    Kitô, Hijiri; Yanagi, Yousuke; Ishida, Shigeyuki; Oka, Kunihiko; Gotoh, Yoshito; Fujihisa, Hiroshi; Yoshida, Yoshiyuki; Iyo, Akira; Eisaki, Hiroshi

    2014-07-01

    We have synthesized a series of intermetallic ternary phosphide chalcogenide superconductors, AP2-xXx (A = Zr, Hf; X = S, Se), using the high-pressure synthesis technique. These materials have a PbFCl-type crystal structure (space group P4/nmm) when x is greater than 0.3. The superconducting transition temperature Tc changes systematically with x, yielding dome-like phase diagrams. The maximum Tc is achieved at approximately x = 0.7, at which point the Tc is 6.3 K for ZrP2-xSex (x = 0.75), 5.5 K for HfP2-xSex (x = 0.7), 5.0 K for ZrP2-xSx (x = 0.675), and 4.6 K for Hfp2-xSx (x = 0.5). They are typical type-II superconductors and the upper and lower critical fields are estimated to be 2.92 T at 0 K and 0.021 T at 2 K for ZrP2-xSex (x = 0.75), respectively.

  7. Power recovery of radiation damaged MOCVD grown indium phosphide on silicon solar cells through argon-ion laser annealing. Master`s thesis

    SciTech Connect

    Boyer, L.L.

    1996-06-01

    This thesis reports the results of a laser annealing technique used to remove defect sites from radiation damaged indium phosphide on silicon MOCVD grown solar cells. This involves the illumination of damaged solar cells with a continuous wave laser to produce a large forward-biased current. The InP/Si cells were irradiated with 1 MeV electrons to a given fluence, and tested for degradation. Light from an argon laser was used to illuminate four cells with an irradiance of 2.5 W/sq cm, producing a current density 3 to 5 times larger than AMO conditions. Cells were annealed at 19 deg C with the laser and at 25 deg C under AMO conditions. Annealing under laser illumination of n/p-type cells resulted in recovery of 48%. P/n type cells lost 4 to 12% of the assumed degradaton. Annealing under AMO conditions resulted in power recovery of 70% in n/p type cells. P/n-type cells recovered approximately 16% of lost power. Results indicate that significant power recovery results from the annealing of defects within n/p type InP/Si solar cells.

  8. Characteristic intraepidermal nerve fibre endings of the intervibrissal fur in the mystacial pad of the rat: morphological details revealed by intravital methylene blue staining and the zinc iodide-osmium tetroxide technique

    PubMed Central

    MÜLLER, T.

    1999-01-01

    Light microscopic observations employing intravital methylene blue staining and impregnation by the zinc iodide-osmium tetroxide technique are presented for intraepidermal nerve fibre endings of the intervibrissal fur in the mystacial pad of the rat snout. Both procedures revealed anatomical details of the intraepidermal nerve fibre plexus in epidermal hillocks often located very close to the mouths of hairs. These nerve fibres appeared to resemble those described in previous immunohistochemical studies as cluster or bush endings. The methylene blue preparations demonstrated the existence of an intensely stained enlargement at the site of the branching point of the nerve fibres which seemed to be functionally related to the development of such nerve fibre plexuses. Due to their close association with hairs, these nerve fibre plexuses are most likely to be mechanoreceptive. Additionally, solitary varicose nerve fibres were found loosely distributed within the epidermis. The visualisation of 2 different morphological types of nerve fibre endings extends the validity of the concept of punctate sensibility into the epidermis. Methylene blue staining appeared to be somewhat superior to the zinc iodide-osmium tetroxide technique. Due to their selectivity for intraepidermal nerve fibres, the methods applied here supplement immunohistochemical procedures in a helpful manner. PMID:10473302

  9. Next-nearest neighbour contributions to P 2p{sub 3/2} X-ray photoelectron binding energy shifts of mixed transition-metal phosphides M{sub 1-x}M'{sub x}P with the MnP-type structure

    SciTech Connect

    Grosvenor, Andrew P. Cavell, Ronald G.; Mar, Arthur

    2007-10-15

    X-ray photoelectron (XPS) and X-ray absorption (XANES) spectroscopic measurements have been made for several series of mixed transition-metal phosphides M{sub 1-x}M'{sub x}P (Co{sub 1-x}Mn{sub x}P, Mn{sub 1-x}V{sub x}P, and Co{sub 1-x}V{sub x}P), which adopt the MnP-type structure (M is more electronegative than M'). The P 2p binding energy shifts displayed by the mixed metal phosphide members do not follow the trend shown by the simple binary phosphides, a deviation which arises from the contribution of next-nearest neighbour effects operating on the primary photoemission site. The magnitude of this contribution can be derived from a simple charge potential model taking the metal electronegativity differences into account. It is suggested that these next-nearest neighbour contributions induce a charge transfer between the two dissimilar metals via metal-metal bonding, which modifies the Madelung potential experienced at the photoemission site. This charge transfer has been confirmed by analysis of the Co 2p XPS spectra as well as the P and Mn K-edge XANES spectra. - Graphical abstract: The mixed phosphides Co{sub 1-x}Mn{sub x}P, Mn{sub 1-x}V{sub x}P, and Co{sub 1-x}V{sub x}P with the MnP-type structure have been studied by use of XPS and XANES. The P 2p binding energies in the mixed phosphides display shifts relative to the binary phosphides that cannot be explained by interaction of the nearest neighbours alone.

  10. Synthesis, X-ray structure, and spectroscopic and electrochemical properties of novel heteronuclear ruthenium-osmium complexes with an asymmetric triazolate bridge

    SciTech Connect

    Hage, R.; Haasnoot, J.G.; Nieuwenhuis, H.A.; Reedijk, J. ); De Ridder, D.J.A. ); Vos, J.G. )

    1990-12-05

    The heterodinuclear compounds ((bpy){sub 2}Ru(bpt)Os(bpy){sub 2})(PF{sub 6}){sub 3} (RuOs) and ((bpy){sub 2}Os(bpt)Ru(bpy){sub 2})(PF{sub 6}){sub 3} (OsRu), where Hbpt = 3,5-bis(pyridin-2-yl)-1,2,4-triazole and bpy = 2,2{prime}-bipyridine, have been prepared and characterized. The crystal and molecular structures of ((Ru(bpy){sub 2}){sub 2}(bpt))(CF{sub 3}SO{sub 3}){sub 3}{center dot}4H{sub 2}O and ((bpy){sub 2}Ru(bpt)Os(bpy){sub 2})(CF{sub 3}SO{sub 3}){sub 3}{center dot}4H{sub 2}O have been determined. Only one of the two possible geometrical isomers of the ruthenium dinuclear compound was found in the crystal structure. The two metal centers are coordinated via N(1) and N(4) of the triazole ring. The metal-metal distance is 6.184 (2) {angstrom}. The NMR data revealed that the OsRu isomer has a similar structure, but with the osmium center bound via N(1) and the ruthenium ion coordinated via N(4) of the triazole ring. The electrochemical potentials of the two heterodinuclear compounds are significantly different; for the RuOs compound the oxidation potentials are 0.73 and 1.20 V, while for the OsRu isomer the oxidation potentials are at 0.65 and 1.30 V vs SCE. These differences in electrochemical behavior between the two isomeric RuOs and OsRu compounds suggest that the N(1) atom of the triazole ring is a better {sigma}-donor than N(4). The mixed-valence dinuclear systems all exhibit rather intense intervalence transition (IT) bands in the near-infrared region, suggesting a moderately strong metal-metal interaction for the bpt systems. A correlation between the energy of the IT bands of the mixed-valence dinuclear complexes and the oxidation potentials has been observed.

  11. Silicon dioxide with a silicon interfacial layer as an insulating gate for highly stable indium phosphide metal-insulator-semiconductor field effect transistors

    NASA Technical Reports Server (NTRS)

    Kapoor, V. J.; Shokrani, M.

    1991-01-01

    A novel gate insulator consisting of silicon dioxide (SiO2) with a thin silicon (Si) interfacial layer has been investigated for high-power microwave indium phosphide (InP) metal-insulator-semiconductor field effect transistors (MISFETs). The role of the silicon interfacial layer on the chemical nature of the SiO2/Si/InP interface was studied by high-resolution X-ray photoelectron spectroscopy. The results indicated that the silicon interfacial layer reacted with the native oxide at the InP surface, thus producing silicon dioxide, while reducing the native oxide which has been shown to be responsible for the instabilities in InP MISFETs. While a 1.2-V hysteresis was present in the capacitance-voltage (C-V) curve of the MIS capacitors with silicon dioxide, less than 0.1 V hysteresis was observed in the C-V curve of the capacitors with the silicon interfacial layer incorporated in the insulator. InP MISFETs fabricated with the silicon dioxide in combination with the silicon interfacial layer exhibited excellent stability with drain current drift of less than 3 percent in 10,000 sec, as compared to 15-18 percent drift in 10,000 sec for devices without the silicon interfacial layer. High-power microwave InP MISFETs with Si/SiO2 gate insulators resulted in an output power density of 1.75 W/mm gate width at 9.7 GHz, with an associated power gain of 2.5 dB and 24 percent power added efficiency.

  12. Synthesis of osmium and ruthenium complexes bearing dimethyl (S,S)-2,2'-(pyridine-2,6-diyl)-bis-(4,5-dihydrooxazol-4-carboxylate) ligand and application to catalytic H/D exchange

    SciTech Connect

    Young, Kenneth J. H.; Lokare, Kapil S.; Leung, Chin Hin; Cheng, Mu-Jeng; Nielsen, Robert J.; Petasis, Nicos A.; Goddard, William A.; Periana, Roy A.

    2011-01-01

    Using tridentate, neutral PyBox ligands, several new osmium and ruthenium complexes [M(PyBox)Cl₂(C₂H₄), where M = Ru, Os] have been prepared, all thermally stable. Some of these PyBox compounds are active for C–H activation of benzene. The Os(PyBox)Cl₂(C₂H₄) complex was characterized by X-ray diffraction. DFT calculations (B3LYP and M06 including Poisson–Boltzmann solvation) corroborate that the Os/PyBox complex in acetic acid (ΔG = 32.0 kcal/mol) is more reactive for benzene C–H activation than Ru/PyBox in basic conditions (ΔG = 34.8 kcal/mol at pH = 13). The stability of hydroxide- and chloride-bridged dinuclear resting states determines calculated barriers.

  13. Osmium Isotope Systematics of Ureilites

    NASA Technical Reports Server (NTRS)

    Rankenburg, K.; Brandon, A. d.; Humayun, M.

    2007-01-01

    The Os-187/Os-188 for twenty-two ureilite whole rock samples, including monomict, augite-bearing, and polymict lithologies, were examined in order to constrain the provenance and subsequent magmatic processing of the ureilite parent body (or bodies). The Re/Os ratios of most ureilites show evidence for a recent disturbance, probably related to Re mobility during weathering, and no meaningful chronological information can be extracted from the present data set. The ureilite Os-187/Os-188 ratios span a range from 0.11739 to 0.13018, with an average of 0.1258+/-0.0023 (1(sigma)), similar to typical carbonaceous chondrites, and distinct from ordinary or enstatite chondrites. The similar mean of Os-187/Os-188 measured for the ureilites and carbonaceous chondrites suggests that the ureilite parent body probably formed within the same region of the solar nebula as carbonaceous chondrites. From the narrow range of the 187Os/188Os distribution in ureilite meteorites it is further concluded that Re was not significantly fractionated from Os during planetary differentiation and was not lost along with the missing ureilitic melt component. The lack of large Re/Os fractionations requires that Re/Os partitioning was controlled by a metal phase, and thus metal had to be stable throughout the interval of magmatic processing on the ureilite parent body.

  14. Phosphide oxides RE2AuP2O (RE = La, Ce, Pr, Nd): synthesis, structure, chemical bonding, magnetism, and 31P and 139La solid state NMR.

    PubMed

    Bartsch, Timo; Wiegand, Thomas; Ren, Jinjun; Eckert, Hellmut; Johrendt, Dirk; Niehaus, Oliver; Eul, Matthias; Pöttgen, Rainer

    2013-02-18

    Polycrystalline samples of the phosphide oxides RE(2)AuP(2)O (RE = La, Ce, Pr, Nd) were obtained from mixtures of the rare earth elements, binary rare earth oxides, gold powder, and red phosphorus in sealed silica tubes. Small single crystals were grown in NaCl/KCl fluxes. The samples were studied by powder X-ray diffraction, and the structures were refined from single crystal diffractometer data: La(2)AuP(2)O type, space group C2/m, a = 1515.2(4), b = 424.63(8), c = 999.2(2) pm, β = 130.90(2)°, wR2 = 0.0410, 1050 F(2) values for Ce(2)AuP(2)O, and a = 1503.6(4), b = 422.77(8), c = 993.0(2) pm, β = 130.88(2)°, wR2 = 0.0401, 1037 F(2) values for Pr(2)AuP(2)O, and a = 1501.87(5), b = 420.85(5), c = 990.3(3) pm, β = 131.12(1)°, wR2 = 0.0944, 1143 F(2) values for Nd(2)AuP(2)O with 38 variables per refinement. The structures are composed of [RE(2)O](4+) polycationic chains of cis-edge-sharing ORE(4/2) tetrahedra and polyanionic strands [AuP(2)](4-), which contain gold in almost trigonal-planar phosphorus coordination by P(3-) and P(2)(4-) entities. The isolated phosphorus atoms and the P(2) pairs in La(2)AuP(2)O could clearly be distinguished by (31)P solid state NMR spectroscopy and assigned on the basis of a double quantum NMR technique. Also, the two crystallographically inequivalent La sites could be distinguished by static (139)La NMR in conjunction with theoretical electric field gradient calculations. Temperature-dependent magnetic susceptibility measurements show diamagnetic behavior for La(2)AuP(2)O. Ce(2)AuP(2)O and Pr(2)AuP(2)O are Curie-Weiss paramagnets with experimental magnetic moments of 2.35 and 3.48 μ(B) per rare earth atom, respectively. Their solid state (31)P MAS NMR spectra are strongly influenced by paramagnetic interactions. Ce(2)AuP(2)O orders antiferromagnetically at 13.1(5) K and shows a metamagnetic transition at 11.5 kOe. Pr(2)AuP(2)O orders ferromagnetically at 7.0 K. PMID:23374070

  15. Gallium phosphide high temperature diodes

    SciTech Connect

    Chaffin, R.J.; Dawson, L.R.

    1981-01-01

    The purpose of this work is to develop high temperature (> 300/sup 0/C) diodes for geothermal and other energy applications. A comparison of reverse leakage currents of Si, GaAs and GaP is made. Diodes made from GaP should be usable to > 500/sup 0/C. An LPE process for producing high quality, grown junction GaP diodes is described. This process uses low vapor pressure Mg as a dopant which allows multiple boat growth in the same LPE run. These LPE wafers have been cut into die and metallized to make the diodes. These diodes produce leakage currents below 10/sup -3/ A/cm/sup 2/ at 400/sup 0/C while exhibiting good high temperature rectification characteristics. High temperature life test data is presented which shows exceptional stability of the V-I characteristics.

  16. K2NaOsO5.5 and K3NaOs2O9: The first osmium perovskites containing alkali cations at the “A” site

    NASA Astrophysics Data System (ADS)

    Mogare, Kailash M.; Klein, Wilhelm; Jansen, Martin

    2012-07-01

    K2NaOsO5.5 and K3NaOs2O9 were obtained from solid-state reactions of potassium superoxide, sodium peroxide and osmium metal at elevated oxygen pressures. K2NaOsO5.5 crystallizes as an oxygen-deficient cubic double perovskite in space group Fm3¯m with a=8.4184(5) Å and contains isolated OsO6 octahedra. K3NaOs2O9 crystallizes hexagonally in P63/mmc with a=5.9998(4) Å and c=14.3053(14) Å. K3NaOs2O9 consists of face sharing Os2O9 pairs of octahedra. According to magnetic measurements K2NaOsO5.5 is diamagnetic, whereas K3NaOs2O9 displays strong antiferromagnetic coupling (TN=140 K), indicating enhanced magnetic interactions within the octahedral pair.

  17. Crystal and electronic structures of CaAl{sub 2}Si{sub 2}-type rare-earth copper zinc phosphides RECuZnP{sub 2} (RE=Pr, Nd, Gd-Tm, Lu)

    SciTech Connect

    Blanchard, Peter E.R.; Stoyko, Stanislav S.; Cavell, Ronald G.; Mar, Arthur

    2011-01-15

    The quaternary rare-earth phosphides RECuZnP{sub 2} (RE=Pr, Nd, Gd-Tm, Lu) have been prepared by reaction of the elements at 900 {sup o}C, completing this versatile series which forms for nearly all RE metals. They adopt the trigonal CaAl{sub 2}Si{sub 2}-type structure (Pearson symbol hP5, space group P3-bar m1, Z=1), as confirmed by single-crystal X-ray diffraction analysis on ErCuZnP{sub 2} and powder X-ray diffraction analysis on the remaining members. The Cu and Zn atoms are assumed to be disordered over the single transition-metal site. Band structure calculations on a hypothetically ordered YCuZnP{sub 2} model suggest a semimetal, with a zero band gap between the valence and conduction bands. This electronic structure is supported by XPS valence band spectra for RECuZnP{sub 2} (RE=Gd-Er), in which the intensity drops off smoothly at the Fermi edge. The absence of a band gap permits the electron count to deviate from the precise value of 16 e{sup -} per formula unit, as demonstrated by the formation of a solid solution in GdCu{sub x}Zn{sub 2-x}P{sub 2} (1.0{<=}x{<=}1.3), while still retaining the CaAl{sub 2}Si{sub 2}-type structure. Because the Cu 2p XPS spectra indicate that the Cu atoms are always monovalent, the substitution of Cu for Zn leads to a decrease in electron count and a lowering of the Fermi level in the valence band. The magnetic susceptibility of RECuZnP{sub 2} (RE=Gd-Er), which obeys the Curie-Weiss law, confirms the presence of trivalent RE atoms. -- Graphical abstract: The absence of a band gap in the semimetallic quaternary rare-earth phosphides RECuZnP{sub 2} permits the formation of a solid solution such as GdCu{sub x}Zn{sub 2-x}P{sub 2} through hole-doping of the valence band. Display Omitted

  18. Photoinduced and chemical oxidation of coordinated imine to amide in isomeric osmium(II) complexes of N-arylpyridine-2-carboxaldimines. Synthesis, characterization, electron transfer properties, and structural studies.

    PubMed

    Ghosh, Amit K; Kamar, Kunal K; Paul, Parimal; Peng, Shie-Ming; Lee, Gene-Hsiang; Goswami, Sreebrata

    2002-12-01

    The reaction of N-arylpyridine-2-carboxaldimine [C(5)H(4)NC(H)NC(6)H(4)R] (HL) with ammonium hexabromoosmate (NH(4))(2)[OsBr(6)] in boiling 2-methoxyethanol afforded a violet solution from which two geometrical isomers of [OsBr(2)(HL)(2)] (1 and 2) were isolated. These are characterized by analytical and spectroscopic data. (1)H NMR spectral data were used for the identification of the isomers. The blue-violet isomer, 1 (designated as ctc), has a 2-fold symmetry axis and gave rise to resonances for only one coordinated HL. The geometry of the ctc-isomer was, however, revealed from the X-ray structure determination of a representative example. The red-violet isomer (2, designated as ccc), on the other hand, is unsymmetrical and gave rise to a large number of proton resonances. The isomeric complexes, [OsBr(2)(HL)(2)], showed intense MLCT transitions in the visible region. This transition, in the ccc-isomer, is slightly (10 nm) red shifted in comparison to the ctc-isomer. These diimine complexes showed one metal based reversible oxidation assignable to the Os(III)/Os(II) process followed by two irreversible oxidations at more anodic potentials (>1.4 V). In addition to these, the complexes also showed two irreversible ligand reductions at high cathodic potentials (<-1.4 V). An unusual type of photochemical transformation of the azomethine function of coordinated HL in osmium compounds 1 is studied. When an air equilibrated acetonitrile solution of 1 was exposed to a xenon lamp, it underwent oxidation affording the mixed ligand, amido complexes of general formula [OsBr(2)(HL)(LO)], 3 (LO = C(5)H(4)NC(O)-N-C(6)H(4)R), in an excellent yield (>95%). This transformation (1 --> 3) was achieved chemically when H(2)O(2) was used as an oxidant. Notably, the chemical oxidation with H(2)O(2) also led to the formation of a tetravalent complex, [OsBr(2)(LO)(2)], 4, as a minor product. Compound 3 was characterized by various spectroscopic and analytical techniques. The room

  19. Determination of osmium concentrations and (187)Os/(188)Os of crude oils and source rocks by coupling high-pressure, high-temperature digestion with sparging OsO(4) into a multicollector inductively coupled plasma mass spectrometer.

    PubMed

    Sen, Indra S; Peucker-Ehrenbrink, Bernhard

    2014-03-18

    The (187)Os/(188)Os ratio that is based on the β(-)-decay of (187)Re to (187)Os (t1/2 = 41.6 billion years) is widely used to investigate petroleum system processes. Despite its broad applicability to studies of hydrocarbon deposits worldwide, a suitable matrix-matched reference material for Os analysis does not exist. In this study, a method that enables Os isotope measurement of crude oil with in-line Os separation and purification from the sample matrix is proposed. The method to analyze Os concentration and (187)Os/(187)Os involves sample digestion under high pressure and high temperature using a high pressure asher (HPA-S, Anton Paar), sparging of volatile osmium tetroxide from the sample solution, and measurements using multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). This methods significantly reduced the total procedural time compared to conventional Carius tube digestion followed by Os separation and purification using solvent extraction, microdistillation and N-TIMS analysis. The method yields Os concentration (28 ± 4 pg g(-1)) and (187)Os/(188)Os (1.62 ± 0.15) of commercially available crude oil reference material NIST 8505 (1 S.D., n = 6). The reference material NIST 8505 is homogeneous with respect to Os concentration at a test portion size of 0.2 g. Therefore, (187)Os/(188)Os composition and Os concentration of NIST 8505 can serve as a matrix-matched reference material for Os analysis. Data quality was assessed by repeated measurements of the USGS shale reference material SCo-1 (sample matrix similar to petroleum source rock) and the widely used Liquid Os Standard solution (LOsSt). The within-laboratory reproducibility of (187)Os/(188)Os for a 5 pg of LOsSt solution, analyzed with this method over a period of 12 months was ∼1.4% (1 S.D., n = 26), respectively. PMID:24552484

  20. Homo- and Heterobimetallic Ruthenium(II) and Osmium(II) Complexes Based on a Pyrene-Biimidazolate Spacer as Efficient DNA-Binding Probes in the Near-Infrared Domain.

    PubMed

    Mardanya, Sourav; Karmakar, Srikanta; Mondal, Debiprasad; Baitalik, Sujoy

    2016-04-01

    We report in this work a new family of homo- and heterobimetallic complexes of the type [(bpy)2M(Py-Biimz)M'(II)(bpy)2](2+) (M = M' = Ru(II) or Os(II); M = Ru(II) and M' = Os(II)) derived from a pyrenyl-biimidazole-based bridge, 2-imidazolylpyreno[4,5-d]imidazole (Py-BiimzH2). The homobimetallic Ru(II) and Os(II) complexes were found to crystallize in monoclinic form with space group P21/n. All the complexes exhibit strong absorptions throughout the entire UV-vis region and also exhibit luminescence at room temperature. For osmium-containing complexes (2 and 3) both the absorption and emission band stretched up to the NIR region and thus afford more biofriendly conditions for probable applications in infrared imaging and phototherapeutic studies. Detailed luminescence studies indicate that the emission originates from the respective (3)MLCT excited state mainly centered in the [M(bpy)2](2+) moiety of the complexes and is only slightly affected by the pyrene moiety. The bimetallic complexes show two successive one-electron reversible metal-centered oxidations in the positive potential window and several reduction processes in the negative potential window. An efficient intramolecular electronic energy transfer is found to occur from the Ru center to the Os-based component in the heterometallic dyad. The binding studies of the complexes with DNA were thoroughly studied through different spectroscopic techniques such as UV-vis absorption, steady-state and time-resolved emission, circular dichroism, and relative DNA binding study using ethidium bromide. The intercalative mode of binding was suggested to be operative in all cases. Finally, computational studies employing DFT and TD-DFT were also carried out to interpret the experimentally observed absorption and emission bands of the complexes. PMID:27011117

  1. K{sub 2}NaOsO{sub 5.5} and K{sub 3}NaOs{sub 2}O{sub 9}: The first osmium perovskites containing alkali cations at the 'A' site

    SciTech Connect

    Mogare, Kailash M.; Klein, Wilhelm; Jansen, Martin

    2012-07-15

    K{sub 2}NaOsO{sub 5.5} and K{sub 3}NaOs{sub 2}O{sub 9} were obtained from solid-state reactions of potassium superoxide, sodium peroxide and osmium metal at elevated oxygen pressures. K{sub 2}NaOsO{sub 5.5} crystallizes as an oxygen-deficient cubic double perovskite in space group Fm3{sup Macron }m with a=8.4184(5) A and contains isolated OsO{sub 6} octahedra. K{sub 3}NaOs{sub 2}O{sub 9} crystallizes hexagonally in P6{sub 3}/mmc with a=5.9998(4) A and c=14.3053(14) A. K{sub 3}NaOs{sub 2}O{sub 9} consists of face sharing Os{sub 2}O{sub 9} pairs of octahedra. According to magnetic measurements K{sub 2}NaOsO{sub 5.5} is diamagnetic, whereas K{sub 3}NaOs{sub 2}O{sub 9} displays strong antiferromagnetic coupling (T{sub N}=140 K), indicating enhanced magnetic interactions within the octahedral pair. - Graphical abstract: High oxidation states of Os, obtained by high oxygen pressure synthesis, are accommodated in double and triple perovskite matrices. K{sub 3}NaOs{sub 2}O{sub 9} displays enhanced magnetic interactions. Highlights: Black-Right-Pointing-Pointer New osmates containing highly oxidized Os were obtained by high O{sub 2} pressure synthesis. Black-Right-Pointing-Pointer High oxidation states of Os are accommodated in double and triple perovskite matrices. Black-Right-Pointing-Pointer Both compounds represent the first Os perovskites with an alkali metal at the A site. Black-Right-Pointing-Pointer K{sub 3}NaOs{sub 2}O{sub 9} displays enhanced magnetic interactions within the octahedral pair.

  2. Use of Tris(2,2′-bipyridine)osmium as a Photoluminescence-Following Electron-Transfer Reagent for Postcolumn Detection in Capillary High-Performance Liquid Chromatography

    PubMed Central

    Jung, Moon Chul; Munro, Nicole; Shi, Guoyue; Michael, Adrian C.; Weber, Stephen G.

    2006-01-01

    The photoluminescence-following electron-transfer (PFET) technique, developed in our laboratory, is a sensitive chromatographic detection method for oxidizable analytes. Because the oxidations are homogeneous, the technique avoids the problem of electrode fouling. A liquid-phase oxidant reacts with the electrochemically active analytes after separation, becoming capable of photoluminescence. Laser-induced photoluminescence is measured to quantitate the analytes. Thus, the electrochemical properties of the oxidant determine the detection selectivity, and the spectroscopic properties define the sensitivity. The properties of tris(2,2′-bipyridine)osmium (1) were investigated for use as the liquid-phase oxidant in the PFET system. The redox potential of the complex is less positive than that of tris(2,2′-bipyridine)ruthenium (2); thus, on-line generation of 13+ by reaction with PbO2, and selective oxidation of catechols by 13+, was possible. The mild oxidizing power of 13+ led to a lower background signal (compared to 23+) when mixed with acidic mobile phases. Photoluminescence from 12+ was much weaker than that from 22+; nonetheless, the system achieved subnanomolar detection limits for dopamine, 3-methoxytyramine, and serotonin. Dopamine and 3-methoxytyramine in rat brain striatal dialysates were determined before and after the injection of nomifensine. The pH of the mobile phase can govern the detection selectivity, since oxidation of most organics is accompanied by proton transfer. Reaction of 1 with catechols showed pH-dependent sensitivity resulting from pH-dependent reaction rate changes. Since the reaction rate is also temperature dependent, increased temperature at the mixer resulted in higher sensitivity. However, the noise level also increased at elevated temperature; thus, the detection limit did not improve. PMID:16536409

  3. Rare-earth manganese copper phosphides REMnCu4P3 (RE = Gd-Ho): the first quaternary ordered variants of the YCo5P3-type structure.

    PubMed

    Ramachandran, Krishna K; Stoyko, Stanislav S; Mullen, C Scott; Mar, Arthur

    2015-02-01

    The quaternary rare-earth phosphides REMnCu(4)P(3) (RE = Gd-Ho) were obtained from direct reactions of the elements at 800 °C. They are the first examples in which ordering of two different transition-metal atoms takes place within the orthorhombic YCo(5)P(3)-type structure [Pearson symbol oP36, space group Pnma, Z = 4; a = 12.667(2)-12.6489(4) Å, b = 3.8119(7)-3.7755(1) Å, and c = 10.895(2)-10.8632(4) Å for RE = Gd-Ho]. Columns of trigonal prisms centered by P atoms are connected in propellor-shaped units in zigzag arrangements to generate square-pyramidal (CN5) sites that are occupied by Mn atoms and tetrahedral sites (CN4) that are occupied by Cu atoms. Spin-polarized band-structure calculations predict that the hypothetical compound YMnCu(4)P(3) will exhibit magnetic ordering. Electrical resistivity measurements on TbMnCu(4)P(3) indicate a poor metal. PMID:25350850

  4. Structure and behavior of the barringerite Ni end-member, Ni[subscript 2]P, at deep Earth conditions and implications for natural Fe-Ni phosphides in planetary cores

    SciTech Connect

    Dera, P.; Lavina, B.; Borkowski, L.A.; Prakapenka, V.B.; Sutton, S.R.; Rivers, M.L.; Downs, R.T.; Boctor, N.Z.; Prewitt, C.T.

    2009-06-01

    High pressure and high temperature behavior of synthetic Ni{sub 2}P has been studied in a laser-heated diamond anvil cell up to 50 GPA and 2200 K. Incongruent melting associated with formation of pyrite-type NiP{sub 2} and amorphous Ni-P alloy was found at an intermediate pressure range, between 6.5 and 40 GPa. Above GPa, Ni{sub 2}P melts congruently. At room conditions, Ni{sub 2}P has hexagonal C22-type structure, and without heating it remains in this structure to at least 50 GPa. With a bulk modulus K{sub 0} = 201(8) GPa and K' = 4.2(6), Ni{sub 2}P is noticeable less compressible than hcp Fe, as well as all previously described iron phosphides, and its presence in the Earth core would favorable lower the core density. In contrast to Fe{sub 2}P, the c/a ratio in Ni{sub 2}P decreases on compression because of the lack of ferromagnetic interaction along the c direction. Lack of the C22{yields}C23 transition in the Ni{sub 2}P rules out a stabilizing effect of Ni on the orthorhombic phase of natural (Fe{sub 1-x}Ni{sub x}){sub 2}P allabogdanite.

  5. GeP and (Ge{sub 1−x}Sn{sub x})(P{sub 1−y}Ge{sub y}) (x≈0.12, y≈0.05): Synthesis, structure, and properties of two-dimensional layered tetrel phosphides

    SciTech Connect

    Lee, Kathleen; Synnestvedt, Sarah; Bellard, Maverick; Kovnir, Kirill

    2015-04-15

    GeP and Sn-doped GeP were synthesized from elements in bismuth and tin flux, respectively. The layered crystal structures of these compounds were characterized by single crystal X-ray diffraction. Both phosphides crystallize in a GaTe structure type in the monoclinic space group C2/m (No. 12) with GeP: a=15.1948(7) Å, b=3.6337(2) Å, c=9.1941(4) Å, β=101.239(2)°; Ge{sub 0.93(3)}P{sub 0.95(1)}Sn{sub 0.12(3)}: a=15.284(9) Å, b=3.622(2) Å, c=9.207(5) Å, β=101.79(1)°. The crystal structure of GeP consists of 2-dimensional GeP layers held together by weak electron lone pair interactions between the phosphorus atoms that confine the layer. Each layer is built of Ge–Ge dumbbells surrounded by a distorted antiprism of phosphorus atoms. Sn-doped GeP has a similar structural motif, but with a significant degree of disorder emphasized by the splitting of all atomic positions. Resistivity measurements together with quantum-chemical calculations reveal semiconducting behavior for the investigated phosphides. - Graphical abstract: Layered phosphides GeP and Sn-doped GeP were synthesized from elements in bismuth and tin flux, respectively. The crystal structure of GeP consists of 2-dimensional GeP layers held together by weak electron lone pair interactions between the phosphorus atoms that confine the layer. Sn-doped GeP has a similar structural motif with a significant degree of disorder emphasized by the splitting of all atomic positions. Resistivity measurements together with quantum-chemical calculations reveal semiconducting behavior for the investigated phosphides. - Highlights: • GeP crystallizes in a layered crystal structure. • Doping of Sn into GeP causes large structural distortions. • GeP is narrow bandgap semiconductor. • Sn-doped GeP exhibits an order of magnitude higher resistivity due to disorder.

  6. Crystal and electronic structures of CaAl 2Si 2-type rare-earth copper zinc phosphides RECuZnP 2 ( RE=Pr, Nd, Gd-Tm, Lu)

    NASA Astrophysics Data System (ADS)

    Blanchard, Peter E. R.; Stoyko, Stanislav S.; Cavell, Ronald G.; Mar, Arthur

    2011-01-01

    The quaternary rare-earth phosphides RECuZnP 2 ( RE=Pr, Nd, Gd-Tm, Lu) have been prepared by reaction of the elements at 900 °C, completing this versatile series which forms for nearly all RE metals. They adopt the trigonal CaAl 2Si 2-type structure (Pearson symbol hP5, space group P3¯ m1, Z=1), as confirmed by single-crystal X-ray diffraction analysis on ErCuZnP 2 and powder X-ray diffraction analysis on the remaining members. The Cu and Zn atoms are assumed to be disordered over the single transition-metal site. Band structure calculations on a hypothetically ordered YCuZnP 2 model suggest a semimetal, with a zero band gap between the valence and conduction bands. This electronic structure is supported by XPS valence band spectra for RECuZnP 2 ( RE=Gd-Er), in which the intensity drops off smoothly at the Fermi edge. The absence of a band gap permits the electron count to deviate from the precise value of 16 e - per formula unit, as demonstrated by the formation of a solid solution in GdCu xZn 2- xP 2 (1.0≤ x≤1.3), while still retaining the CaAl 2Si 2-type structure. Because the Cu 2 p XPS spectra indicate that the Cu atoms are always monovalent, the substitution of Cu for Zn leads to a decrease in electron count and a lowering of the Fermi level in the valence band. The magnetic susceptibility of RECuZnP 2 ( RE=Gd-Er), which obeys the Curie-Weiss law, confirms the presence of trivalent RE atoms.

  7. Is osmium chemically fractionated in the moon

    NASA Technical Reports Server (NTRS)

    Hertogen, J.; Janssens, M.-J.

    1977-01-01

    An investigation was conducted involving the determination of Os in 53 highland samples from the Apollo 14-17 missions. The Os/Ir ratio was found to remain essentially constant at 1.05 as Os and Ir abundances vary over four orders of magnitude. The Os-Au and the Os-Ni correlation in highland samples is presented in graphs. The graphs show that the majority of highland samples have Os/Au and Os/Ni ratios somewhat below the cosmic value. But there is no reason to attribute this trend to a loss of Os by local processes, because two other refractory siderophiles, Ir and Re, show exactly the same trend. Results on more than 150 analyzed highland samples show that meteoritic groups of low (Ir, Re, Os)/Au ratio are much more common at the Apollo landing sites than are groups of high ratio.

  8. Progress in indium phosphide solar cell research

    NASA Technical Reports Server (NTRS)

    Weinberg, Irving; Swartz, Clifford K.; Hart, R. E., Jr.

    1989-01-01

    Progress, dating from the start of the Lewis program, is reviewed emphasizing processing techniques which have achieved the highest efficiencies in a given year. To date, the most significant achievement has been attainment of AM0 total area efficiencies approaching 19 percent. Although closed tube diffusion is not considered to be an optimum process, reasonably efficient 2cm x 2cm and 1cm x 2cm InP cells have been produced in quantity by this method with a satellite to be launched in 1990 using these cells. Proton irradiation of these relatively large area cells indicates radiation resistance comparable to that previously reported for smaller InP cells. A similar result is found for the initial proton irradiations of ITO/InP cells processed by D. C. sputtering. With respect to computer modelling, a comparison of n/p homojunction InP and GaAs cells of identical geometries and dopant concentrations has confirmed the superior radiation resistance of InP cells under 1 MeV electron irradiations.

  9. Development of high temperature gallium phosphide rectifiers

    NASA Technical Reports Server (NTRS)

    Craford, M. G.; Keune, D. L.

    1972-01-01

    Large area high performance, GaP rectifiers were fabricated by means of Zn diffusion into vapor phase epitaxial GaP. Devices with an active area of 0.01 sq cm typically exhibit forward voltages of 3 volts for a bias current of 1 ampere and have reverse breakdown voltages of 300 volts for temperatures from 27 C to 400 C. Typical device reverse saturation current at a reverse bias of 150 volts is less than 10 to the minus 9th power amp at 27 C and less than 0.000050 amp at 400 C.

  10. Minority carrier lifetime in indium phosphide

    NASA Technical Reports Server (NTRS)

    Jenkins, Phillip; Landis, Geoffrey A.; Weinberg, Irving; Kneisel, Keith

    1991-01-01

    Transient photoluminescence is used to measure the minority carrier lifetime on n-type and p-type InP wafers. The measurements show that unprocessed InP wafers have very high minority carrier lifetimes. Lifetimes of 200 ns and 700 ns were observed for lightly-doped p- and n-type material respectively. Lifetimes over 5 ns were found in heavily doped n-type material.

  11. Miocene to Pliocene osmium isotopic records of Mediterranean sediments

    NASA Astrophysics Data System (ADS)

    Kuroda, Junichiro; Jiménez-Espejo, Francisco J.; Nozaki, Tatsuo; Gennari, Rocco; Lugli, Stefano; Manzi, Vinicio; Roveri, Marco; Flecker, Rachel; Suzuki, Katsuhiko; Yoshimura, Toshihiro; Sierro, Francisco; Ohkouchi, Naohiko

    2015-04-01

    In the late Miocene the Mediterranean Sea experienced a salinity crisis and thick sequences of evaporites precipitated across the basin. In this study we report Os isotopic records from drilled cores in the Mediterranean; the Balearic Sea, the Tyrrhenian Sea, the Ionian Basin and the Florence Rise. Pliocene sediments at all sites show 187Os/188Os values close to that of the coeval ocean water, indicating that the Mediterranean was connected to the North Atlantic. Evaporitic sediments deposited during the late Miocene however, have 187Os/188Os values lower than coeval ocean water values and samples from the eastern Mediterranean and Ionian basins are particularly low. Os isotopic ratios of the pre-evaporite sediments in the western Mediterranean are almost identical to that of the coeval ocean water. In contrast, equivalent sediments from the Florence Rise have significantly lower 187Os/188Os values. The offset of Mediterranean evaporite 187Os/188Os is attributed to limited exchange with the North Atlantic during the Messinian Salinity Crisis (MSC). The source of unradiogenic Os is likely to be weathering of ultramafic rocks (ophiolites) cropping out in the Mediterranean's drainage basins. The offset in the Os ratio on the Florence Rise is attributed either to limited water exchange between eastern and western Mediterranean, or to local effects associated with exhumation of ophiolites around the eastern Mediterranean Sea.

  12. Miocene to Pleistocene osmium isotopic records of the Mediterranean sediments

    NASA Astrophysics Data System (ADS)

    Kuroda, Junichiro; Jiménez-Espejo, Francisco J.; Nozaki, Tatsuo; Gennari, Rocco; Lugli, Stefano; Manzi, Vinicio; Roveri, Marco; Flecker, Rachel; Sierro, Francisco J.; Yoshimura, Toshihiro; Suzuki, Katsuhiko; Ohkouchi, Naohiko

    2016-01-01

    In the late Miocene the Mediterranean Sea experienced a salinity crisis and thick sequences of evaporites precipitated across the deep and marginal basins. In this study we report Os isotopic records from Deep Sea Drilling Project and Ocean Drilling Project cores in the Mediterranean: the Balearic Sea (Site 372), the Tyrrhenian Sea (Site 654), the Ionian Basin (Site 374), and the Florence Rise (Sites 375-376), as well as Integrated Ocean Drilling Project Site U1387 in Gulf of Cadiz, North Atlantic. Pliocene-Pleistocene sediments at all sites show 187Os/188Os values close to that of the coeval ocean water, indicating that the Mediterranean was connected to the North Atlantic. Evaporitic sediments deposited during the latest Miocene, however, have 187Os/188Os values significantly lower than coeval ocean water values. The offset of the Mediterranean evaporite 187Os/188Os is attributed to limited exchange with the North Atlantic during the Messinian salinity crisis. The source of unradiogenic Os is likely to be weathering of ultramafic rocks (ophiolites) cropping out in the Mediterranean's drainage basins. Based on a box model we estimated the amount of unradiogenic Os and the Atlantic-Mediterranean exchange rate to explain this offset. Os isotopic ratios of the pre-evaporite sediments in the western Mediterranean are almost identical to that of the coeval ocean water. In contrast, equivalent sediments from the Florence Rise have significantly lower 187Os/188Os values. The offset in the Os isotopic ratio on the Florence Rise is attributed either to limited water exchange between eastern and western Mediterranean or to local effects associated with exhumation of the Troodos ophiolites (Cyprus).

  13. High-Resolution Laser Spectroscopy on the Negative Osmium Ion

    SciTech Connect

    Warring, U.; Amoretti, M.; Canali, C.; Fischer, A.; Heyne, R.; Meier, J. O.; Morhard, Ch.; Kellerbauer, A.

    2009-01-30

    We have applied a combination of laser excitation and electric-field detachment to negative atomic ions for the first time, resulting in an enhancement of the excited-state detection efficiency for spectroscopy by at least 2 orders of magnitude. Applying the new method, a measurement of the bound-bound electric-dipole transition frequency in {sup 192}Os{sup -} was performed using collinear spectroscopy with a narrow-bandwidth cw laser. The transition frequency was found to be 257.831 190(35) THz [wavelength 1162.747 06(16) nm, wave number 8600.3227(12) cm{sup -1}], in agreement with the only prior measurement, but with more than 100-fold higher precision.

  14. Negative thermal ion mass spectrometry of osmium, rhenium, and iridium

    NASA Technical Reports Server (NTRS)

    Creaser, R. A.; Papanastassiou, D. A.; Wasserburg, G. J.

    1991-01-01

    This paper describes a technique for obtaining, in a conventional surface ionization mass spectrometer, intense ion beams of negatively charged oxides of Os, Re, and Ir by thermal ionization. It is shown that the principal ion species of these ions are OsO3(-), ReO4(-), and IrO2(-), respectively. For Re-187/Os-187 studies, this technique offers the advantage of isotopic analyses without prior chemical separation of Re from Os.

  15. Cationic Dihydrogen/Dihydride Complexes of Osmium: Structure and Dynamics

    SciTech Connect

    Egbert, Jonathan D.; Bullock, R. Morris; Heinekey, D. M.

    2007-03-22

    Reaction of Cp*Os(CO)2Cl with (Et3Si )(BArF4) under hydrogen gas affords the cationic hydrogen complex [Cp*Os(CO)2(H2)][BArF4] (1), (Cp* = C5Me5; ArF = C6F5). When this reaction is carried out with HD gas, complex 1-d1 results, with JHD = 24.5 Hz. When solutions of complex 1 are monitored by 1H NMR spectroscopy over several days, the gradual formation of a trans dihydride species is observed. Similarly, reaction of CpOs(dppm)Br with NaBArF*4 (ArF* = 3,5-(CF3)2C6H3) under hydrogen affords the cationic dihydride complex [CpOs(dppm)H2]BArF*4 (2). At 295 K, complex 2 exists as a 10:1 mixture of cis and trans isomers. The 1H NMR spectrum of the cis form in the hydride region exhibits a triplet with JHP = 6.5 Hz, due to rapid exchange of the hydrogen atoms. At low temperature, static spectra of the HH'PP' spin system can be obtained, revealing quantum mechanical exchange coupling between the two hydride ligands. The observed JHH' is temperature dependent, varying from 133 Hz at 141 K to 176 Hz at 198 K. This is the first report of detectable exchange coupling between pairs of chemically equivalent hydrogen atoms. Research at the University of Washington was supported by the National Science Foundation. Research at Brookhaven National Laboratory was carried out under contract DE-AC02-98CH10886 with the U.S. Department of Energy and was supported by its Division of Chemical Sciences, Office of Basic Energy Sciences. Research at Pacific Northwest National Laboratory (PNNL) was funded by LDRD funds. PNNL is operated by Battelle for the US Department of Energy.

  16. Subnanosecond isomerization in an osmium-dimethyl sulfoxide complex.

    PubMed

    Mockus, Nicholas V; Petersen, Jeffrey L; Rack, Jeffrey J

    2006-01-01

    We report the structure, spectroscopy, and electrochemistry of cis-[Os(bpy)(2)(DMSO)(2)](OTf)(2), where bpy is 2,2'-bipyridine, DMSO is dimethyl sulfoxide, and OTf is trifluoromethanesulfonate. Electrochemical measurements are consistent with S-to-O isomerization following the oxidation of Os(2+) (1.8 V vs Ag/AgCl). Visible irradiation of the metal-to-ligand charge-transfer transition (355 nm) of [Os(bpy)(2)(DMSO)(2)](2+) in the solid state and solution yields an emissive S-bonded excited state and S-to-O excited-state isomerization on a subnanosecond time scale. These results and a comparison to the nonphotoactive [Os(bpy)(2)Cl(DMSO)](+) are discussed. PMID:16390034

  17. Osmium Solubility in Silicate Melts: New Efforts and New Results

    NASA Technical Reports Server (NTRS)

    Borisov, A.; Walker, R. J.

    1998-01-01

    In a recent paper, Borisov and Palme reported the first experimental results on the partitioning of Os between metal (Ni-rich OsNi alloys) and silicate melt of anorthite-diopside eutectic composition at 1400 C and 1 atm total pressure and and at function of O2 from 10(exp -8) to 10(exp -12) atm. Experiments were done by equilibrating OsNi metal loops with silicate melt. Metal and glass were analyzed separately by INAA. D(sup 0s) ranged from 10(exp 6) to 10(exp 7), which is inconsistent with core/ mantle equilibrium for HSEs and favors the late veneer hypothesis. Unfortunately, there was practically no function of O2 dependence of Os partitioning, and the scatter of experimental results was quite serious, so the formation of Os nuggets was suspected. This new set of experiments was specifically designed to avoid of at least minimize the nugget problem

  18. Systematic Osmium Isotope Binary Mixing Arrays in Arc Volcanism

    NASA Astrophysics Data System (ADS)

    Alves, S.; Alves, S.; Schiano, P.; Capmas, F.; Allegre, C. J.

    2001-12-01

    Isotopic and geochemical studies on subduction-related lavas aim at constraining the nature of their mantle sources and the respective roles of source heterogeneity and petrogenetic processes in their compositions. Many components are potentially involved in producing the geochemical signatures of arc lavas: depleted mantle, subducted oceanic crust and sediments, and the overlying continental or oceanic crust. A further complication in characterizing mantle sources of arc lavas is complex mixing of some component parts via derivative fluids or melts released from the slab. Os isotope ratios are potential tracers of slab contribution in arc lavas because 1) subducted sediments are very radiogenic in Os compared to the upper mantle, and 2) Re behaves as a moderately incompatible element during mantle partial melting, whereas Os is highly compatible. Therefore, MORB have much higher Re/Os ratios than peridotites. Consequently, old oceanic crust is likely to be extremely more radiogenic than the depleted upper mantle so that recycled basaltic components should be identified by their elevated 187Os/188Os ratios. Os isotope ratios and Os and Re concentrations have been measured in 55 lavas coming from 10 different subduction zones. Samples span a large range of major element concentrations (from basalts to dacites) and Mg# (from 0.32 to 0.81). The 10 subduction zones, namely the Lesser Antilles, Java, Papua-New Guinea, the Philippines, Izu-Bonin, Kamchatka, the Aleutians, Mexico, Colombia and Peru-Chile, have a range of basement nature and thickness, as well as a range of age and sediment cover of the subducting plate. Measured 187Os/188Os ratios range from 0.130 to 1.524 and Os concentrations range from 0.048 to 46 ppt. Re concentrations range from 37 to 915 ppt. Os initial isotope ratios are systematically positively and linearly correlated with the inverse of Os concentrations in arc lavas from a given volcano, indicating that the Os isotopic compositions always reflect a binary mixing process. All trends converge towards unradiogenic compositions similar to those of upper mantle peridotites. These mixing relationships might be ascribed to a general contamination process; however, a single shallow-level process of crustal assimilation is hardly reconciled with the diversity of basements (from oceanic crust to continental crust compositions) of the selected arc volcanoes, the occurrence of the mixing lines for both primary and differentiated samples, the temporal variations observed for a given volcano, and the absence of co-variations between Os contents, isotope ratios, and indices of differentiation. On the other hand, the radiogenic components may be simply explained by varying the amount of oceanic crust and sediments in the source of these arc lavas. Similar mixing relationships are also seen at the sample scale, which suggests that the Os distribution in the magma prevents the mantle unradiogenic Os to equilibrate with the radiogenic Os coming from the subducted materials transferred via fluids or melts.

  19. Osmium isotope binary mixing arrays in arc volcanism

    NASA Astrophysics Data System (ADS)

    Alves, Sophie; Schiano, Pierre; Capmas, Françoise; Allègre, Claude J.

    2002-05-01

    Os isotope ratios and Os and Re concentrations were measured in 56 lavas coming from 10 different subduction zones. Samples span a large range of major element concentrations (from basalts to dacites) and Mg# (from 0.32 to 0.81). The 10 subduction zones, namely the Lesser Antilles, Java, Papua New Guinea, the Philippines, Izu-Bonin, Kamchatka, the Aleutians, Mexico, Colombia and Peru-Chile, have a range of geodynamic settings. Measured 187Os/ 188Os ratios range from 0.130 to 1.524 and Os concentrations range from 0.05 to 46 ppt. Re concentrations range from 24 to 915 ppt. Os initial isotope ratios are systematically positively and linearly correlated with the inverse of Os concentrations in arc lavas from a given volcano, indicating that the Os isotopic compositions always reflect a binary mixing process. Similar mixing relationships are also seen at the sample scale. All trends converge towards unradiogenic compositions similar to those of upper mantle peridotites. These mixing relationships might be ascribed to a general contamination process; however, a single shallow-level process of crustal assimilation is hardly reconciled with the diversity of basements (from oceanic crust to continental crust compositions) of the selected arc volcanoes, the occurrence of the mixing lines for both primary and differentiated samples, and the absence of covariations between Os contents, isotope ratios, and indices of contamination and differentiation. On the other hand, because subducted components are very radiogenic and differ from one zone to another, the radiogenic components may be explained by varying amounts and natures of oceanic crust and sediments in the source of arc lavas. However, this explanation implies two disequilibrium processes, first during magma formation in order to produce heterogeneous lavas, and second during magma ascent to the surface to preserve slab signatures.

  20. Evidence for an ancient osmium isotopic reservoir in Earth.

    PubMed

    Meibom, Anders; Frei, Robert

    2002-04-19

    Iridosmine grains from placer deposits associated with peridotite-bearing ophiolites in the Klamath mountains have extremely radiogenic 186Os/188Os ratios and old Re-Os minimum ages, from 256 to 2644 million years. This indicates the existence of an ancient platinum group element reservoir with a supra-chondritic Pt/Os ratio. Such a ratio may be produced in the outer core as a result of inner core crystallization that fractionates Os from Pt. However, if the iridosmine Os isotopic compositions are a signature of the outer core, then the inner core must have formed very early, within several hundred million years after the accretion of Earth. PMID:11964475

  1. Hydrodechlorination of polychlorinated molecules using transition metal phosphide catalysts.

    PubMed

    Cecilia, J A; Infantes-Molina, A; Rodríguez-Castellón, E

    2015-10-15

    Ni2P and CoP catalysts (5 wt.% of metal) supported on a commercial SiO2 were tested in the gas phase catalytic hydrodechlorination (HDCl) of mono (chlorobenzene-ClB) and polychlorobenzenes (PCBs) (1,2- dichlorobenzene (1,2-DClB), 1,3-dichlorobenzene (1,3-DClB), 1,4-dichlorobenzene (1,4-DClB), and 1,2,4-trichlorobenzene (1,2,4-TClB)) at atmospheric pressure. It was investigated how the number and position of chlorine atoms in the molecule influence the HDCl activity. The prepared catalysts were characterized by X-ray diffraction (XRD), CO chemisorption, N2 adsorption-desorption at -196°C, and X-ray photoelectron spectroscopy (XPS). Characterization results indicated better active phase dispersion and greater amount of P on the Ni2P catalyst surface. Catalytic results showed that the Ni2P was more active and stable in this type of reactions. The hydrodechlorination activity decreased by increasing the number of chlorine atoms in the molecule and chlorine substituents in close proximity. The observed trend in the HDCl activity was: ClB>1,4-DClB>1,3-DClB>1,2-DClB>1,2,4-TClB. The exception was the catalytic response after 24h on stream observed for the Ni2P in the HDCl reaction of 1,2,4-TClB, which was equal to that observed for the 1,4-DClB molecule, and also yielding benzene as the main reaction product. PMID:25913677

  2. Spectroscopic properties of colloidal indium phosphide quantum wires

    SciTech Connect

    Wang, Lin-Wang; Wang, Fudong; Yu, Heng; Li, Jingbo; Hang, Qingling; Zemlyanov, Dmitry; Gibbons, Patrick C.; Wang, Lin-Wang; Janes, David B.; Buhro, William E.

    2008-07-11

    Colloidal InP quantum wires are grown by the solution-liquid-solid (SLS) method, and passivated with the traditional quantum dots surfactants 1-hexadecylamine and tri-n-octylphosphine oxide. The size dependence of the band gaps in the wires are determined from the absorption spectra, and compared to other experimental results for InP quantum dots and wires, and to the predictions of theory. The photoluminescence behavior of the wires is also investigated. Efforts to enhance photoluminescence efficiencies through photochemical etching in the presence of HF result only in photochemical thinning or photo-oxidation, without a significant influence on quantum-wire photoluminescence. However, photo-oxidation produces residual dot and rod domains within the wires, which are luminescent. The results establish that the quantum-wire band gaps are weakly influenced by the nature of the surface passivation, and that colloidal quantum wires have intrinsically low photoluminescence efficiencies.

  3. Room temperature particle detectors based on indium phosphide

    NASA Astrophysics Data System (ADS)

    Yatskiv, R.; Grym, J.; Zdansky, K.; Pekarek, L.

    2010-01-01

    A study of electrical properties and detection performance of particle detectors based on bulk InP and semiconducting LPE layers operated at room temperature is presented. Bulk detectors were fabricated on semi-insulating InP crystals grown by liquid-encapsulated Czochralski (LEC) technique. High purity InP layers of both n- and p-type conductivity were used to fabricate detector structures with p-n junction. The detection performance of particle detectors was measured by pulse-height spectra with alpha particles emitted from 241Am source at room temperature. Better noise properties were achieved for detectors with p-n junctions due to better quality contacts on p-type layers.

  4. The Cleaning of Indium Phosphide Substrates for Growth by MBE

    NASA Astrophysics Data System (ADS)

    Hofstra, Peter

    1995-11-01

    A novel technique of using an in-situ ECR generated H-plasma to produce high quality surfaces on InP substrates, for growth of n-and p-type InP layers by GSMBE, has been investigated. The initial substrate surface quality determines the quality of the subsequently grown layers and therefore, the cleaning procedure is of critical importance. The standard approach entails a thermal desorption of a passivating oxide; however, this technique leaves carbon on the surface and, because oxides may vary in composition depending on the growth conditions, a consistent temperature for desorption may not be obtained. The desorption process is also dependent on the atmosphere in which it is carried out; i.e. whether an overpressure of P_2 or As _2 is used. Thermal desorption of oxides from InP requires the substrate to reach temperatures higher than normal GSMBE growth temperatures which can lead to substrate decomposition and, for regrowth applications, can alter dopant profiles and layer composition in ternary and quaternary layer growths. As an alternative, H-plasmas in separate vacuum chambers have been used to remove oxides from InP but this typically produces highly defective substrates due to a loss of phosphorus from the substrate. In this work the combination of an in-situ H-plasma with a stabilizing atmosphere of P_2 is used for the removal of oxides at temperatures equal to growth temperature and below. The mechanism involved in the thermal desorption of an oxide is first clarified and this procedure is compared with oxide removal by H-plasma etch in a phosphorus atmosphere. The ECR source can produce various plasma modes which have been thoroughly characterized. The effect of the different plasma conditions on clean InP is determined. These modes have different properties which result in different oxide etch rates. Various modes are compared and the mechanism of oxide removal is documented. As an alternative to oxide growth S-passivation has recently received attention as a surface passivation technique. Application of this surface, with and without H-plasma cleaning, has been investigated. The above treatments and other wet chemical surface treatments are compared to determine the optimal surface cleaning technique. The results indicate that thermal desorptions are driven by reaction with phosphorus from the substrate and therefore require high temperatures to promote significant phosphorus evaporation from the substrate. A H-plasma etch of the oxide is driven by the presence of atomic M in the plasma and results in the formation of water. Oxide removal rates were determine at various temperatures from 250^circC-490^ circC. The plasma etch was found to remove carbon contamination from the surface whereas, thermal desorptions do not. Defect levels in the underlying InP are sensitive to the plasma properties but with careful choice of plasma conditions defect states can be minimized. An optimal surface cleaning procedure has been developed which involves a UV-ozone treatment and H-plasma cleaning, resulting in interfaces free of electrically active defects in n -type material and a defect concentration of 8times10 ^{11} cm^{ -2} in p-type material.

  5. Indium Phosphide Nanocrystals Formed in Silica by Sequential Ion Implantation

    SciTech Connect

    Denmark, D.; Ueda, A.; Shao, C. L.; Wu, M. H.; Mu, R.; White, Clark W; Vlahovic, B.; Muntele, C. I.; Ila, Dr. Daryush; Liu, Y. C.

    2005-01-01

    Fused silica substrates were implanted with: (1) phosphorus only, (2) indium only, and (3) phosphorus plus indium ions. Vibrational and electronic characterizations have been performed on the P only and In only samples to obtain an understanding of the thermal annealing behavior in order to obtain a meaningful guide for the fabrication of InP quantum dots (QDs) formed by sequential ion implantation of In and P in SiO{sub 2}. Thermal annealing procedures for InP synthesis have been established and InP quantum dots are confirmed by TEM, XRD and far infrared measurements. Far IR spectra show a single resonance at 323 cm{sup -1} rather than two absorption peaks in its counterpart of bulk InP crystals. The single band absorption is attributed to the surface phonon of InP quantum dots which will appear between transverse optical (TO) and longitudinal optical (LO) phonon modes of the bulk.

  6. Observation of Weyl nodes and Fermi arcs in tantalum phosphide

    PubMed Central

    Xu, N.; Weng, H. M.; Lv, B. Q.; Matt, C. E.; Park, J.; Bisti, F.; Strocov, V. N.; Gawryluk, D.; Pomjakushina, E.; Conder, K.; Plumb, N. C.; Radovic, M.; Autès, G.; Yazyev, O. V.; Fang, Z.; Dai, X.; Qian, T.; Mesot, J.; Ding, H.; Shi, M.

    2016-01-01

    A Weyl semimetal possesses spin-polarized band-crossings, called Weyl nodes, connected by topological surface arcs. The low-energy excitations near the crossing points behave the same as massless Weyl fermions, leading to exotic properties like chiral anomaly. To have the transport properties dominated by Weyl fermions, Weyl nodes need to locate nearly at the chemical potential and enclosed by pairs of individual Fermi surfaces with non-zero Fermi Chern numbers. Combining angle-resolved photoemission spectroscopy and first-principles calculation, here we show that TaP is a Weyl semimetal with only a single type of Weyl fermions, topologically distinguished from TaAs where two types of Weyl fermions contribute to the low-energy physical properties. The simple Weyl fermions in TaP are not only of fundamental interests but also of great potential for future applications. Fermi arcs on the Ta-terminated surface are observed, which appear in a different pattern from that on the As-termination in TaAs and NbAs. PMID:26983910

  7. Synthesis of actinide nitrides, phosphides, sulfides and oxides

    DOEpatents

    Van Der Sluys, William G.; Burns, Carol J.; Smith, David C.

    1992-01-01

    A process of preparing an actinide compound of the formula An.sub.x Z.sub.y wherein An is an actinide metal atom selected from the group consisting of thorium, uranium, plutonium, neptunium, and americium, x is selected from the group consisting of one, two or three, Z is a main group element atom selected from the group consisting of nitrogen, phosphorus, oxygen and sulfur and y is selected from the group consisting of one, two, three or four, by admixing an actinide organometallic precursor wherein said actinide is selected from the group consisting of thorium, uranium, plutonium, neptunium, and americium, a suitable solvent and a protic Lewis base selected from the group consisting of ammonia, phosphine, hydrogen sulfide and water, at temperatures and for time sufficient to form an intermediate actinide complex, heating said intermediate actinide complex at temperatures and for time sufficient to form the actinide compound, and a process of depositing a thin film of such an actinide compound, e.g., uranium mononitride, by subliming an actinide organometallic precursor, e.g., a uranium amide precursor, in the presence of an effectgive amount of a protic Lewis base, e.g., ammonia, within a reactor at temperatures and for time sufficient to form a thin film of the actinide compound, are disclosed.

  8. Experimental study of the hydrogen complexes in indium phosphide

    NASA Astrophysics Data System (ADS)

    Darwich, R.; Pajot, B.; Rose, B.; Robein, D.; Theys, B.; Rahbi, R.; Porte, C.; Gendron, F.

    1993-12-01

    The structure of the H-related complexes in p-type InP and in liquid encapsulated Czochralski semi-insulating InP:Fe has been studied from the vibrational absorption of their PH stretching modes. The acceptor complexes are produced by plasma hydrogenation so that PD modes have been investigated also. The study has first been performed at 6 K on the fundamentals and on the most intense of the first overtones. The trends in the frequencies and widths of the PH modes of the H-acceptor complexes for Be, Zn, and Cd acceptors are discussed and explained qualitatively. In InP:Fe, the PH intrinsic modes are sharper than those of the acceptor complexes indicating a weaker interaction with the environment. This study has been followed by the measurement of the temperature dependence of the frequencies and of the linewidths for increasing temperatures. The frequency shifts and the broadenings of the lines are interpreted by the temperature-dependent random dephasing of the vibration of the high-frequency oscillators in the excited state. The analysis shows that the PH mode in the acceptor complexes couples to TA phonons of the InP lattice while the one in the complexes involving a vacancy couples to a two TA phonon combination. The anharmonicity of the P-H bonds is comparable to the one in phosphine. A comparison of the anharmonicity parameters derived from the overtone measurements with those derived from the hydrogen isotope effects gives evidence of the interaction between the H atom and the lattice. The amplitude of vibration of the D atom is smaller than that of the H atom and this explains why the interaction of the D atom with the lattice is smaller. This is the reason why the width of the PD modes is smaller than that of the corresponding PH modes. The splitting of some of the PH lines in samples subjected to a uniaxial stress has been studied. The splitting of the PH;Zn mode is in full agreement with a P-H bond along a <111> axis. The same <111> orientation of the P-H bond is also found from the splitting of a line attributed to an In vacancy ``decorated'' by a H atom (VIn(PH)). The splitting of the strongest line in InP:Fe leads to its attribution to a PH mode in a cubic center containing four H atoms (VIn(PH)4). The presence of this center seems to account for most of the hydrogen present in InP:Fe. Upon annealing of the InP:Fe samples, VIn(PH)4 is a source of atomic hydrogen that can be trapped by other defects and it can leave partially hydrogenated In vacancies.

  9. Indium phosphide negative electron affinity photocathodes: Surface cleaning and activation

    NASA Astrophysics Data System (ADS)

    Sun, Yun

    InP(100) is a very important semi-conductor for many applications. When activated by Cs and oxygen, the InP surface achieves the state of Negative Electron Affinity (NEA) making the Cs+O/InP system a very efficient electron source. Despite many years of study, the chemical cleaning and activation of InP are still not well understood. In our work, we have established an understanding of the basic physics and chemistry for the chemical cleaning and activation of the InP(100) surface. Synchrotron Radiation Photoelectron Spectroscopy is the main technique used in this study because of its high surface sensitivity and ability to identify chemical species present on the surface at each stage of our process. A clean, stoichiometric InP(100) surface is crucial for obtaining high performance of NEA photocathodes. Therefore, the first part of our study focused on the chemical cleaning of InP(100). We found that hydrogen peroxide based solutions alone, originally developed to clean GaAs(100) surfaces and widely used for InP(100), do not result in clean InP(I00) surfaces because oxide is left on the surface. A second cleaning step, which uses acid solutions like HCl or H2SO4, can remove all the oxide and leave a 0.4 ML protective layer of elemental phosphorous on the surface. The elemental phosphorous can be removed by annealing at 330°C and a clean InP(100) surface can be obtained. Cs deposition on InP(100) surface shows clear charge transfer from the Cs ad-atoms to the substrate. When the Cs/InP(100) surface is dosed with oxygen, the charge transfer from the Cs to substrate is reduced and substrate is oxidized. The activation of InP as a NEA photocathode is carried out by an alternating series of steps consisting of Cs deposition and Cs+O co-deposition. Two types of oxygen are found after activation. The first is dissociated oxygen and the other is a di-oxygen species (peroxide or superoxide). The decay of quantum-yield with time and with annealing is studied and changes in both the Cs oxide and oxidation of substrate are observed, which we conclude are the causes for the decrease of the quantum yield.

  10. Zinc and phosphorus co-implantation in indium phosphide

    SciTech Connect

    Yu, K.M.; Ridgway, M.C.

    1998-07-01

    Electrical activation and dopant diffusion in Zn-implanted InP after rapid thermal annealing have been investigated. For an as-implanted Zn concentration of {approximately}4{times}10{sup 19}thinspcm{sup {minus}3}, only {approximately}7{percent} of the implanted Zn atoms formed electrically active shallow acceptors following a 950thinsp{degree}C/5 s annealing cycle. The low activation was the result of rapid Zn out-diffusion{emdash}only {approximately}14{percent} of the implanted dopant was retained after annealing. A significant enhancement in electrical activation and a reduction in Zn loss were achieved in Zn+P co-implanted samples which yielded a net hole concentration of {le}6{times}10{sup 18}thinspcm{sup {minus}3} and {gt}50{percent} Zn retention. The saturation of the free hole concentration in Zn+P co-implanted samples was attributed to the formation of Zn interstitial donors and Group-V-related donor-type native defects. For comparison, Zn+Al and Zn+Al+P co-implanted samples were also examined to distinguish the relative influences of implantation-induced disorder and nonstoichiometry on electrical activation and dopant diffusion. For the given implant conditions, we found that nonstoichiometry was the dominant influence. {copyright} {ital 1998 American Institute of Physics.}

  11. Modelling and design of high performance indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Rhoads, Sandra L.; Barnett, Allen M.

    1989-01-01

    A first principles pn junction device model has predicted new designs for high voltage, high efficiency InP solar cells. Measured InP material properties were applied and device parameters (thicknesses and doping) were adjusted to obtain optimal performance designs. Results indicate that p/n InP designs will provide higher voltages and higher energy conversion efficiencies than n/p structures. Improvements to n/p structures for increased efficiency are predicted. These new designs exploit the high absorption capabilities, relatively long diffusion lengths, and modest surface recombination velocities characteristic of InP. Predictions of performance indicate achievable open-circuit voltage values as high as 943 mV for InP and a practical maximum AM0 efficiency of 22.5 percent at 1 sun and 27 C. The details of the model, the optimal InP structure and the effect of individual parameter variations on device performance are presented.

  12. Ion-implanted high microwave power indium phosphide transistors

    NASA Technical Reports Server (NTRS)

    Biedenbender, Michael D.; Kapoor, Vik J.; Messick, Louis J.; Nguyen, Richard

    1989-01-01

    Encapsulated rapid thermal annealing (RTA) has been used in the fabrication of InP power MISFETs with ion-implanted source, drain, and active-channel regions. The MISFETs had a gate length of 1.4 microns. Six to ten gate fingers per device, with individual gate finger widths of 100 or 125 microns, were used to make MISFETs with total gate widths of 0.75, 0.8, or 1 mm. The source and drain contact regions and the channel region of the MISFETs were fabricated using Si implants in InP at energies from 60 to 360 keV with doses of (1-560) x 10 to the 12th/sq cm. The implants were activated using RTA at 700 C for 30 sec in N2 or H2 ambients using an Si3N4 encapsulant. The high-power high-efficiency MISFETs were characterized at 9.7 GHz, and the output microwave power density for the RTA conditions used was as high as 2.4 W/mm. For a 1-W input at 9.7 GHz gains up to 3.7 dB were observed, with an associated power-added efficiency of 29 percent and output power density 70 percent greater than that of GaAs MESFETs.

  13. A review of indium phosphide space solar cell fabrication technology

    NASA Technical Reports Server (NTRS)

    Spitzer, M. B.; Dingle, B.; Dingle, J.; Morrison, R.

    1990-01-01

    A review of the status of InP cell efficiency and of approaches to the reduction of cell cost is presented. The use of heteroepitaxial techniques such as InP-on-GaAs and InP-on-Si is discussed along with the use of chemical and mechanical techniques for removal and recovery of the substrate. The efficiency ultimately obtainable with designs made possible by such an approach is calculated.

  14. Plasma deposited silicon nitride for indium phosphide encapsulation

    NASA Technical Reports Server (NTRS)

    Valco, G. J.; Kapoor, V. J.; Biedenbender, M. D.; Williams, W. D.

    1989-01-01

    The composition and the annealing characteristics of plasma-deposited silicon-nitride encapsulating films on the ion-implanted InP substrates were investigated, using two different substrate-cleaning procedures (organic solvents and HF or HIO3 solutions) prior to encapsulation. The effect of plasma deposition of silicon nitride on the InP substrates was assessed through the current-voltage characteristics of Schottky diodes. Results of XPS analyses showed that the cleaning procedure that employed HF solution left less oxygen on the InP surface than the procedure involving HIO3. No chemical interaction between the film and the substrate was observed before or after annealing.

  15. 40 CFR 180.284 - Zinc phosphide; tolerances for residues.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... agricultural commodities as follows: Commodity Parts per million Alfalfa, forage 0.2 Alfalfa, hay 0.2 Barley... Expiration/Revocation Date Alfalfa, forage 1.0 12/31/05 Alfalfa, hay 1.0 12/31/05 Clover, forage 0.1...

  16. Structure of the (110) antiphase boundary in gallium phosphide.

    PubMed

    Cohen, D; Carter, C B

    2002-11-01

    The morphology of antiphase boundaries in GaP films grown by molecular beam epitaxy on Si (001) has been studied by transmission electron microscopy. The inversion of the crystal polarity between antiphase domains was confirmed by convergent-beam electron diffraction. The APBs were often found to facet parallel to [110] planes. Strong-beam alpha-fringe contrast observed along the (110) facets indicates that adjacent antiphase domains are related by an additional rigid-body lattice translation. Diffraction-contrast analysis shows that this R corresponds to a shear parallel to the [001] direction and a small expansion. The magnitude of the translation was inferred, quantitatively, through a comparison between energy-filtered zero-loss images of the alpha-fringe contrast with numerical calculations. The components of the rigid-body lattice translation were determined to be 0.023 +/- 0.0033 nm in the [001] direction and 0.005 +/- 0.002 nm in the 0 direction. Based upon a geometric model of the [110] antiphase boundary, the lengths of the Ga and P antisite bonds were calculated to be 254 +/- 2 pm and 227 +/- 4 pm, respectively. PMID:12423259

  17. The β-polymorph of uranium phosphide selenide

    PubMed Central

    Oh, George N.; Ibers, James A.

    2011-01-01

    β-UPSe was synthesized from the reaction of U2Se3, P and Se in a CsCl flux in a fused-silica tube. It crystallizes with four formula units in the tetra­gonal space group I4/mmm in the UGeTe structure type. The asymmetric unit comprises one U (site symmetry 4mm), one Se (4mm), and one P (mmm.) atom. The U atom is coordinated in a monocapped square-anti­prismatic arrangement, where the square face is formed by P atoms and the other five vertices are Se atoms. The P site is disordered about a mirror plane, showing half-ocupancy for each of the two resulting P atoms. The title structure is related to that of α-UPSe, which crystallizes with two formula units in the tetra­gonal space group P4/nmm in the PbFCl structure type. PMID:22199473

  18. Measurement of surface recombination velocity on heavily doped indium phosphide

    NASA Technical Reports Server (NTRS)

    Jenkins, Phillip; Ghalla-Goradia, Manju; Faur, Mircea; Faur, Maria; Bailey, Sheila

    1990-01-01

    Surface recombination velocity (SRV) on heavily doped n-type and p-type InP was measured as a function of surface treatment. For the limited range of substrates and surface treatments studied, SRV and surface stability depend strongly on the surface treatment. SRVs of 100,000 cm/sec in both p-type and n-type InP are obtainable, but in n-type the low-SRV surfaces were unstable, and the only stable surfaces on n-type had SRVs of more than 10to the 6th cm/sec.

  19. Indium phosphide/cadmium sulfide thin-film solar cells

    SciTech Connect

    Zanio, K.

    1980-02-01

    Thin-film InP/CdS structures were prepared by depositing, in sequence, ITO on a low-cost glass substrate, CdS on the ITO by thermal evaporation, and InP on the CdS by planar reactive deposition (PRD). Films of CdS, 15 ..mu..m thick, were recrystallized in flowing H/sub 2//H/sub 2/S at 500/sup 0/C. Lateral dimensions of typical grains were 50..mu..m with values up to 200 ..mu..m. The sheet resistance of the recrystallized CdS (RXCdS) was lowered from greater than 10/sup 5/ ..cap omega../O = cm/sup 2/ to values as low as 16 ..cap omega../O = cm/sup 2/ by annealing in either H/sub 2/ Cd atmospheres. Epitaxy of InP was undertaken on (100) InP at a substrate temperature of 320/sup 0/C. Room-temperature electron mobilities of about 2000 cm/sup 2//V-sec were found. Mobilities and hole concentrations of 60 cm/sup 2//V-sec and 10/sup 17/ cm-/sup 3/, respectively, were achieved with Be-doped films. P-type films with hole concentrations as high as a few times 10/sup 18/cm-/sup 3/ were achieved with increased doping. Be-doped InP was deposited onto the RXCdS/ITO/GLASS substrate to form a thin-film cell. However, p-type InP could not be prepared with CdS as a substrat4e, presumably due to interdiffusion or vapor transport of sulfur. Consequently, blocking action and a photovoltage could only be achieved using a gold Schottky barrier on the InP/RXCdS/ITO/GLASS structure. Plans for the next quarter include determining whether n-type doping from the CdS occurs by either interdiffusion or vapor transport, characterizing InP epitaxy on the RXCdS, and preparing additional thin-film structures.

  20. Electron microscopy imaging of proteins on gallium phosphide semiconductor nanowires

    NASA Astrophysics Data System (ADS)

    Hjort, Martin; Bauer, Mikael; Gunnarsson, Stefan; Mårsell, Erik; Zakharov, Alexei A.; Karlsson, Gunnel; Sanfins, Elodie; Prinz, Christelle N.; Wallenberg, Reine; Cedervall, Tommy; Mikkelsen, Anders

    2016-02-01

    We have imaged GaP nanowires (NWs) incubated with human laminin, serum albumin (HSA), and blood plasma using both cryo-transmission electron microscopy and synchrotron based X-ray photoemission electron microscopy. This extensive imaging methodology simultaneously reveals structural, chemical and morphological details of individual nanowires and the adsorbed proteins. We found that the proteins bind to NWs, forming coronas with thicknesses close to the proteins' hydrodynamic diameters. We could directly image how laminin is extending from the NWs, maximizing the number of proteins bound to the NWs. NWs incubated with both laminin and HSA show protein coronas with a similar appearance to NWs incubated with laminin alone, indicating that the presence of HSA does not affect the laminin conformation on the NWs. In blood plasma, an intermediate sized corona around the NWs indicates a corona with a mixture of plasma proteins. The ability to directly visualize proteins on nanostructures in situ holds great promise for assessing the conformation and thickness of the protein corona, which is key to understanding and predicting the properties of engineered nanomaterials in a biological environment.We have imaged GaP nanowires (NWs) incubated with human laminin, serum albumin (HSA), and blood plasma using both cryo-transmission electron microscopy and synchrotron based X-ray photoemission electron microscopy. This extensive imaging methodology simultaneously reveals structural, chemical and morphological details of individual nanowires and the adsorbed proteins. We found that the proteins bind to NWs, forming coronas with thicknesses close to the proteins' hydrodynamic diameters. We could directly image how laminin is extending from the NWs, maximizing the number of proteins bound to the NWs. NWs incubated with both laminin and HSA show protein coronas with a similar appearance to NWs incubated with laminin alone, indicating that the presence of HSA does not affect the laminin conformation on the NWs. In blood plasma, an intermediate sized corona around the NWs indicates a corona with a mixture of plasma proteins. The ability to directly visualize proteins on nanostructures in situ holds great promise for assessing the conformation and thickness of the protein corona, which is key to understanding and predicting the properties of engineered nanomaterials in a biological environment. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08888g

  1. Observation of Weyl nodes and Fermi arcs in tantalum phosphide

    NASA Astrophysics Data System (ADS)

    Xu, N.; Weng, H. M.; Lv, B. Q.; Matt, C. E.; Park, J.; Bisti, F.; Strocov, V. N.; Gawryluk, D.; Pomjakushina, E.; Conder, K.; Plumb, N. C.; Radovic, M.; Autès, G.; Yazyev, O. V.; Fang, Z.; Dai, X.; Qian, T.; Mesot, J.; Ding, H.; Shi, M.

    2016-03-01

    A Weyl semimetal possesses spin-polarized band-crossings, called Weyl nodes, connected by topological surface arcs. The low-energy excitations near the crossing points behave the same as massless Weyl fermions, leading to exotic properties like chiral anomaly. To have the transport properties dominated by Weyl fermions, Weyl nodes need to locate nearly at the chemical potential and enclosed by pairs of individual Fermi surfaces with non-zero Fermi Chern numbers. Combining angle-resolved photoemission spectroscopy and first-principles calculation, here we show that TaP is a Weyl semimetal with only a single type of Weyl fermions, topologically distinguished from TaAs where two types of Weyl fermions contribute to the low-energy physical properties. The simple Weyl fermions in TaP are not only of fundamental interests but also of great potential for future applications. Fermi arcs on the Ta-terminated surface are observed, which appear in a different pattern from that on the As-termination in TaAs and NbAs.

  2. THz sources using indium phosphide high electron mobility transistors

    NASA Astrophysics Data System (ADS)

    Deal, W. R.

    2013-09-01

    In the last few years, InP HEMT maximum frequency of oscillation (fMAX) has pushed well beyond 1 THz (1000 GHz). This implies that solid state amplification is possible to frequencies approaching 1 THz. In this paper, we provide an overview of power amplifier and power generation work which has been done using InP HEMT technology. In particular, power generation has been demonstrated to 0.67 THz

  3. Observation of Weyl nodes and Fermi arcs in tantalum phosphide.

    PubMed

    Xu, N; Weng, H M; Lv, B Q; Matt, C E; Park, J; Bisti, F; Strocov, V N; Gawryluk, D; Pomjakushina, E; Conder, K; Plumb, N C; Radovic, M; Autès, G; Yazyev, O V; Fang, Z; Dai, X; Qian, T; Mesot, J; Ding, H; Shi, M

    2016-01-01

    A Weyl semimetal possesses spin-polarized band-crossings, called Weyl nodes, connected by topological surface arcs. The low-energy excitations near the crossing points behave the same as massless Weyl fermions, leading to exotic properties like chiral anomaly. To have the transport properties dominated by Weyl fermions, Weyl nodes need to locate nearly at the chemical potential and enclosed by pairs of individual Fermi surfaces with non-zero Fermi Chern numbers. Combining angle-resolved photoemission spectroscopy and first-principles calculation, here we show that TaP is a Weyl semimetal with only a single type of Weyl fermions, topologically distinguished from TaAs where two types of Weyl fermions contribute to the low-energy physical properties. The simple Weyl fermions in TaP are not only of fundamental interests but also of great potential for future applications. Fermi arcs on the Ta-terminated surface are observed, which appear in a different pattern from that on the As-termination in TaAs and NbAs. PMID:26983910

  4. Strongly-guided indium phosphide/indium gallium arsenic phosphide Mach-Zehnder modulator for optical communications

    NASA Astrophysics Data System (ADS)

    Betty, Ian Brian

    2006-12-01

    The development of strongly-guided InP/In1-x GaxAsyP 1-y based Mach-Zehnder optical modulators for 10Gb/s telecommunications is detailed. The modulators have insertion losses including coupling as low as 4.5dB, due to the incorporation of monolithically integrated optical mode spot-size converters (SSC's). The modulators are optimized to produce system performance that is independent of optical coupling alignment and for wavelength operation between 1525nm and 1565nm. A negatively chirped Mach-Zehnder modulator design is demonstrated, giving optimal dispersion-limited reach for 10Gb/s ON/OFF-keying modulation. It is shown that the optical system performance for this design can be determined from purely DC based optical measurements. A Mach-Zehnder modulator design invoking nearly no transient frequency shifts under intensity modulation is also presented, for the first time, using phase-shifter implementations based on the Quantum-Confined-Stark-Effect (QCSE). The performance impact on the modulator from the higher-order vertical and lateral waveguide modes found in strongly-guided waveguides has been determined. The impact of these higher-order modes has been minimized using the design of the waveguide bends, MMI structures, and doping profiles. The fabrication process and optical design for the spot-size mode converters are also thoroughly explored. The SSC structures are based on butt-joined vertically tapered passive waveguide cores within laterally flared strongly-guided ridges, making them compatible with any strong-guiding waveguide structure. The flexibility of the SSC process is demonstrated by the superior performance it has also enabled in a 40Gb/s electro-absorption modulator. The presented electro-absorption modulator has 3.6dB fiber-to-fiber insertion loss, polarization dependent loss (PDL) of only 0.3dB over 15dB extinction, and low absolute chirp (|alpha H| < 0.6) over the full dynamic range.

  5. Cluster synthesis. 38. Formation of high-nuclearity platinum-osmium cluster complexes. Synthesis, structural characterizations, and interrelationships of Pt[sub 4]Os[sub 6](CO)[sub 22](COD), Pt[sub 5]Os[sub 6](CO)[sub 21](COD)[sub 2], Pt[sub 4]Os[sub 6](CO)[sub 19](COD)[sub 2], and Pt[sub 7]Os[sub 6](CO)[sub 21](COD)[sub 2] (COD = cycloocta-1,5-diene)

    SciTech Connect

    Adams, R.D.; Jauching Lii; Wengan Wu )

    1992-06-10

    The chemistry of heteronuclear cluster complexes containing Pt has attracted a great deal of interest becasue of the importance of Pt alloys to the process of catalytic petroleum reforming. Three new high-nuclearity Pt-Os carbonyl cluster complexes Pt[sub 4]Os[sub 6](CO)[sub 22](COD) (2), Pt[sub 5]Os[sub 6](CO)[sub 21](COD)[sub 2] (3), and Pt[sub 4]Os[sub 6](CO)[sub 19](COD)[sub 2] (4) were obtained in 17%, 13%, and 9% yields, respectively, from the pyrolysis of Pt[sub 2]Os[sub 3](CO)[sub 10](COD)[sub 2] (1) under a CO atmosphere at 128C. Compounds 2-4 were characterized by IR, [sup 1]H NMR, and single-crystal X-ray diffraction analyses. Compound 2 consists of two Pt[sub 3]Os[sub 3] octahedra sharing a Pt[sub 3] triangular face. A Pt(COD) group caps one of the Os[sub 3] triangular faces. Compound 3 is structurally similar to compound 2 but has an additional Pt(COD) group capping one of the PtOs[sub 2] triangular faces. The cluster of compound 4 can be viewed as a meta-bicapped Pt[sub 2]Os[sub 4] octahedron with an additional Pt(COD) group capping a PtOs[sub 2] traingle to one of the capping groups on the octahedron and a Pt(COD) group bridging the Pt-Pt edge of the octahedron. Compound 2 was converted to 4 in 65% yield, when it was irradiated in the presence of COD. When compound 2 was treated with 1 equiv of trimethylamine N-oxide and 2 equiv of Pt(COD)[sub 2], compound 3 and a new higher nuclearity platinum-osmium carbonyl complex Pt[sub 7]Os[sub 6](CO)[sub 21](COD)[sub 2] (5; 8% yeild) were obtained. Compound 5 was characterized by a single-crystal X-ray diffraction analysis. It was formed by the loss of one CO from 2 and the addition of three Pt atoms and one COD ligand. Compound 2 was converted to the known compound Pt[sub 4]Os[sub 6](CO)[sub 21](COD)([mu]-H)[sub 2] in good yield (79%) by reacting with trimethylamine N-oxide and hydrogen.

  6. Square-Planar Alkylidyne-Osmium and Five-Coordinate Alkylidene-Osmium Complexes: Controlling the Transformation from Hydride-Alkylidyne to Alkylidene.

    PubMed

    Buil, María L; Cardo, Juan J F; Esteruelas, Miguel A; Oñate, Enrique

    2016-08-01

    Square-planar alkylidyne and five-coordinate alkylidene mixed (i)Pr3P-Os-IPr (IPr = 1,3-bis(diisopropylphenyl)imidazolylidene) complexes have been discovered and characterized, and their formation has been rationalized. The cationic five-coordinate hydride-alkylidyne compounds [OsHX(≡CPh)(IPr)(P(i)Pr3)]OTf (X = Cl (1), F (4); OTf = CF3SO3) undergo deprotonation with KO(t)Bu to afford the trans-halide-alkylidyne square-planar derivatives OsX(≡CPh)(IPr)(P(i)Pr3) (X = Cl (2), F (5)). Oxidative addition of the C(sp)-H bond of phenylacetylene and methyl propiolate along the Cl-Os-CPh axis of 2 with the hydrogen atom directed to the alkylidyne leads to alkynyl-cis-hydride-alkylidyne intermediates, which rapidly evolve into the five-coordinate alkylidene complexes Os(C≡CR)Cl(═CHPh)(IPr)(P(i)Pr3) (R = Ph (6), CO2Me (7)) as a consequence of the migration of the hydride from the metal center to the Cα atom of the alkylidyne. Oxidative addition of the C(sp)-H bond of methyl propiolate along the X-Os-CPh axis of 2 and 5 with the hydrogen atom directed to the halide gives the alkynyl-trans-hydride-alkylidyne derivatives OsH(C≡CCO2Me)X(≡CPh)(IPr)(P(i)Pr3) (X = Cl (8), F (9)). Complex 8 evolves into 7. However, complex 9 containing the stronger π-donor fluoride is stable. The oxidative addition of HCl to 2 selectively yields the cis-hydride-alkylidyne compound OsHCl2(≡CPh)(IPr)(P(i)Pr3) (10), which is also stable. PMID:27405004

  7. Production of tungsten-188 and osmium-194 in a nuclear reactor for new clinical generators

    SciTech Connect

    Mirzadeh, S.; Knapp, F.F. Jr.; Callahan, A.P.

    1991-01-01

    Rhenium-188 and iridium-194 are potential candidates for radioimmunotherapy with monoclonal antibodies directed against tumor-associated antigens. Both nuclei are short-lived and decay by high energy {Beta}{minus} emission. In addition, both nuclei emit {gamma}-rays with energy suitable for imaging. An important characteristics is availability of {sup 188}Re and {sup 194}Ir from decay of reactor-produced parents ({sup 188}W and {sup 194}Os, respectively) in convenient generator systems. The {sup 188}W and {sup 194}Os are produced by double neutron capture of {sup 186}W and {sup 192}Os, respectively. The large scale production yields of {sup 188}W in several nuclear reactors will be presented. We also report a new management for the cross-section of {sup 193}Os(n,{gamma}){sup 194}Os reaction and discuss the feasibility of producing sufficient quantities of {sup 194}Os. 17 refs., 1 fig., 2 tabs.

  8. Oxygen - Osmium Isotopic Compositions of West Maui Lavas and the Link to Oceanic Lithosphere

    NASA Astrophysics Data System (ADS)

    Gaffney, A. M.; Nelson, B. K.; Reisberg, L.; Eiler, J. M.

    2003-12-01

    We use stratigraphically-controlled sequences of late shield-stage lavas from West Maui to investigate age-dependence and fine-scale complexity of chemical variation within this Kea-type Hawaiian volcano. With new O and Os isotope data we identify unique geochemical signals indicative of complex processes of mixing among source components. In W. Maui lavas, δ 18O and 187Os/188Os range from 4.5 to 5.2 and 0.1316 to 0.1394, respectively. One sample (187Os/188Os =0.158) has very low [Os] (20 ppt) and likely has been severely contaminated by shallow oceanic crust. These compositions, as well as 87Sr/86Sr (0.7034-0.7037) and 206Pb/204Pb (18.36-18.54), are typical of shield-stage lavas from other Kea-type volcanoes. Some W. Maui compositional variability correlates with stratigraphic height. All shallow samples have 187Os/188Os>=0.1333, and all deep samples have 187Os/188Os<=0.1330. The deep samples show a negative 187Os/188Os - 87Sr/86Sr correlation, but the shallow samples show no Os - Sr isotopic correlation. 187Os/188Os correlates with no other measured isotopic compositions except for δ 18O, for which the deep and shallow samples define two sub-parallel inversely correlated trends. δ 18O shows no other correlation with stratigraphy or other measured isotopic tracers. The inverse O-Os isotopic correlation of W. Maui is distinct from that observed for other Hawaiian volcanoes (e.g. Mauna Kea, Koolau) or within the Hawaiian suite as a whole. Age-dependent sampling of at least three components is required to describe the O-Os-Sr isotopic variation we observe at W. Maui. Similar intra-volcano correlation in 87Sr/86Sr - 206Pb/204Pb - trace element compositions is consistent with mixing of small-degree partial melts of gabbroic oceanic crust with plume-derived Kea-type magmas. We infer that this gabbroic endmemember is characterized by δ 18O < 4.5 and 187Os/188Os > 0.133. The remainder of the variability is the result of short-lived chemical heterogeneities in the Kea plume endmember.

  9. Mirror-Image Organometallic Osmium Arene Iminopyridine Halido Complexes Exhibit Similar Potent Anticancer Activity

    PubMed Central

    Fu, Ying; Soni, Rina; Romero, María J; Pizarro, Ana M; Salassa, Luca; Clarkson, Guy J; Hearn, Jessica M; Habtemariam, Abraha; Wills, Martin; Sadler, Peter J

    2013-01-01

    Four chiral OsII arene anticancer complexes have been isolated by fractional crystallization. The two iodido complexes, (SOs,SC)-[Os(η6-p-cym)(ImpyMe)I]PF6 (complex 2, (S)-ImpyMe: N-(2-pyridylmethylene)-(S)-1-phenylethylamine) and (ROs,RC)-[Os(η6-p-cym)(ImpyMe)I]PF6 (complex 4, (R)-ImpyMe: N-(2-pyridylmethylene)-(R)-1-phenylethylamine), showed higher anticancer activity (lower IC50 values) towards A2780 human ovarian cancer cells than cisplatin and were more active than the two chlorido derivatives, (SOs,SC)-[Os(η6-p-cym)(ImpyMe)Cl]PF6, 1, and (ROs,RC)-[Os(η6-p-cym)(ImpyMe)Cl]PF6, 3. The two iodido complexes were evaluated in the National Cancer Institute 60-cell-line screen, by using the COMPARE algorithm. This showed that the two potent iodido complexes, 2 (NSC: D-758116/1) and 4 (NSC: D-758118/1), share surprisingly similar cancer cell selectivity patterns with the anti-microtubule drug, vinblastine sulfate. However, no direct effect on tubulin polymerization was found for 2 and 4, an observation that appears to indicate a novel mechanism of action. In addition, complexes 2 and 4 demonstrated potential as transfer-hydrogenation catalysts for imine reduction. PMID:24114923

  10. Development of the Osmium-191->Iridium-191m radionuclide generator. Annual report

    SciTech Connect

    Treves, S.; Packard, A.

    1984-05-01

    The use of the ultrashort-lived radionuclide IR-191m (T/sub 1/2/=5s) for radionuclide angiography results in a lower patient radiation dose, higher photon flux, and allows repeated studies that are not possible with the radionuclide currently employed for these studies (Tc-99m, T/sub 1/2/=6h). The Os-191->Ir-191m generator currently being used in clinical studies suffers, however, from low Ir-191m yield (10%), high Os-191 breakthrough (5 x 10/sup -3/%), and an eluent (at pH 1) that must be buffered prior to injection. Initial efforts to improve the performance of this generator met with only limited success. We have, therefore, concentrated on the development of a completely new generator system. In the last year these investigations have led to a new generator of improved Ir-191m yield (20 to 25%), dramatically lower Os-191 breakthrough (5 x 10/sup -4/%), and an eluent that does not require buffering prior to injection. In addition, this generator has been found to be stable for at least 10 days and does not require a scavenger column to achieve low breakthrough. Clinical studies have continued at Children's Hospital in pediatric patients and at Beth Israel Hospital in adult patients. 19 references, 1 figure, 10 tables.

  11. Osmium(ii) complexes for light-driven aerobic oxidation of amines to imines.

    PubMed

    Li, Yong-Hui; Liu, Xiao-Le; Yu, Zhen-Tao; Li, Zhao-Sheng; Yan, Shi-Cheng; Chen, Guang-Hui; Zou, Zhi-Gang

    2016-08-01

    Herein, we describe the synthesis and characterization of three Os(ii) complexes (i.e., [Os(fptz)2(PPhMe2)2] (1, fptzH = 3-trifluoromethyl-5-pyridyl-1,2,4-triazole), [Os(fptz)2(CO)(L1)] (2, L1 = PPh3; 3, L1 = pyridine)) that have been successfully utilized as good photocatalysts to promote aerobic oxidative coupling of amines to imines with molecular oxygen in air as a green oxidant. Complex 1 is the most effective catalyst for the oxidative coupling of benzylamine with molecular O2 (air) as the oxidant because of the complex's strong absorption of visible light and long-lived triplet state. The application of a low catalyst loading (0.06 mol%) of complex 1 to the oxidative coupling of a wide range of amines affords the corresponding imines efficiently and selectively in most cases. The reaction mechanism was investigated via relevant control and quenching experiments. The results indicated that the reaction occurs via an active (1)O2-involved pathway. The (1)O2-generating ability of complex 1 as a photosensitizer was evaluated using 9,10-dimethylanthracene (DMA) as a chemical trap for (1)O2. PMID:27431765

  12. Osmium Isotope and Highly Siderophile Element Compositions of Lunar Orange and Green Glasses

    NASA Technical Reports Server (NTRS)

    Walker, R. J.; Horan, M. F.; Shearer, C. K.; Papike, J. J.

    2003-01-01

    The absolute and relative abundances of the highly siderophile elements (HSE) present in planetary mantles are primarily controlled by: 1) silicate-metal partitioning during core-mantle differentiation, 2) the subsequent addition of HSE to mantles via continued planetary accretion. Consequently, constraints on the absolute and relative abundances of the HSE in the lunar mantle will provide unique insights to the formation and late accretionary history of not only the Moon, but also Earth. Determining the HSE content of the lunar mantle, however, has proven difficult, because no bona fide mantle rocks have been collected from the moon. The only materials presently available for constraining mantle abundances are lunar volcanic rocks. Lunar basalts typically have very low concentrations of HSE and highly fractionated HSE patterns. Because of our extremely limited understanding of mantle melt partitioning of the HSE, even for terrestrial systems, extrapolations to mantle compositions from basaltic compositions are difficult, except possibly for the less compatible HSE Pt and Pd. Primitive, presumably less fractionated materials, such as picritic glasses are potentially more diagnostic of the lunar interior. Here we report Os isotopic composition data and Re, Os, Ir, Ru, Pt and Pd concentration data for green glass (15426,164) and orange glass (74001,1217). As with previous studies utilizing neutron activation analysis, we are examining different size fractions of the spherules to assess the role of surface condensation in the generation of the HSE abundances.

  13. Sources of osmium to the modern oceans: New evidence from the 190Pt-186Os system

    USGS Publications Warehouse

    McDaniel, D.K.; Walker, R.J.; Hemming, S.R.; Horan, M.F.; Becker, H.; Grauch, R.I.

    2004-01-01

    High precision Os isotope analysis of young marine manganese nodules indicate that whereas the composition of modern seawater is radiogenic with respect to 187Os/188Os, it has 186Os/188Os that is within uncertainty of the chondritic value. Marine Mn nodule compositions thus indicate that the average continental source of Os to modern seawater had long-term high Re/Os compared to Pt/Os. Analyses of loess and freshwater Mn nodules support existing evidence that average upper continental crust (UCC) has resolvably suprachondritic 186Os/188Os, as well as radiogenic 187Os/188Os. Modeling the composition of seawater as a two-component mixture of oceanic/cosmic Os with chondritic Os compositions and continentally-derived Os demonstrates that, insofar as estimates for the composition of average UCC are accurate, congruently weathered average UCC cannot be the sole continental source of Os to seawater. Our analysis of four Cambrian black shales confirm that organic-rich sediments can have 187Os/188Os ratios that are much higher than average UCC, but 186Os/188Os compositions that are generally between those of chondrites and average-UCC. Preferential weathering of black shales can result in dissolved Os discharged to the ocean basins that has a much lower 186Os/188Os than does average upper crust. Modeling the available data demonstrates that augmentation of estimated average UCC compositions with less than 0.1% additional black shale and 1.4% additional ultramafic rock can produce a continental end-member Os isotopic composition that satisfies the requirements imposed by the marine Mn nodule data. The interplay of these two sources provides a mechanism by which the 187Os/188Os of seawater can change as sources and weathering conditions change, yet seawater 186Os/188Os varies only minimally. ?? 2004 Elsevier Ltd.

  14. Highly Siderophile Elements and Osmium Isotope Systematics in Ureilites: Are the Carbonaceous Veins Primary Components?

    NASA Technical Reports Server (NTRS)

    Rankenburg, K.; Brandon, A. D.; Humayun, M.

    2005-01-01

    Ureilites are an enigmatic group of primitive carbon-bearing achondrites of ultramafic composition. The majority of the 143 ureilite meteorites consist primarily of olivine and pyroxene (and occasionally chromite) [1]. They are coarse-grained, slowly cooled, and depleted in incompatible lithophile elements. Minor amounts of dark interstitial material consisting of carbon, metal, sulfides, and fine-grained silicates occur primarily along silicate grain boundaries, but also intrude the silicates along fractures and cleavage planes. Variable degrees of impact shock features have also been imparted on ureilites. The prevailing two origins proposed for these rocks are either as melting residues of carbonaceous chondritic material [2], [3], or alternatively, derivation as mineral cumulates from such melts [4], [5], [6]. It has recently been proposed that ureilites are the residues of a smelting event, i.e. residues of a partial melting event under highly reducing conditions, where a solid Fe-bearing phase reacts with a melt and carbon to form Fe metal and carbon monoxide [7]. Rapid, localized extraction and loss of the basaltic component into space resulting from high eruption velocities could preserve unequilibrated oxygen isotopes and produce the observed olivine-pyroxene residues via 25-30% partial melting of chondritic-like precursor material.

  15. The synthesis and unexpected solution chemistry of thermochromic carborane-containing osmium half-sandwich complexes.

    PubMed

    Pitto-Barry, Anaïs; South, Amy; Rodger, Alison; Barry, Nicolas P E

    2016-01-28

    The functionalisation of the 16-electron complex [Os(η(6)-p-cymene)(1,2-dicarba-closo-dodecarborane-1,2-dithiolato)] (1) with a series of Lewis bases to give the 18-electron complexes of general formula [Os(η(6)-p-cymene)(1,2-dicarba-closo-dodecarborane-1,2-dithiolato)(L)] (L = pyridine (2), 4-dimethylaminopyridine (3), 4-cyanopyridine (4), 4-methoxypyridine (5), pyrazine (6), pyridazine (7), 4,4'-bipyridine (8) and triphenylphosphine (9)) is reported. All 18-electron complexes are in equilibrium in solution with the 16-electron precursor, and thermochromic properties are observed in some cases (2, 3, 5, 8, and 9). The binding constants and Gibbs free energies of the equilibria are determined using UV-visible titrations and their stabilities investigated. Synthetic routes for forcing the formation of the 18-electron species are proposed, and analytical methods to characterise the equilibria are described. PMID:26700880

  16. CHIRAL-AT-METAL OSMIUM(VI) PHOSPHINE COMPLEXES. (R829553)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  17. Rhenium-osmium isotope systematics in meteorites I: Magmatic iron meteorite groups IIAB and IIIAB

    USGS Publications Warehouse

    Morgan, J.W.; Walker, R.J.; Grossman, J.N.

    1992-01-01

    Using resonance ionization mass spectrometry (RIMS), Re and Os abundances were determined by isotope dilution (ID) and 187Os 186Os ratios measured in nineteen iron meteorites: eight from group IIAB, ten from group IIIAB, and Treysa (IIIB anomalous). Abundances range from 1.4 to 4800 ppb Re, and from 13 to 65000 ppb Os, and generally agree well with previous ID and neutron activation (NAA) results. The Re and Os data suggest that abundance trends in these iron groups may be entirely explained by fractional crystallization. Addition of late-formed metal to produce ReOs variation in the B subgroups is not essential but cannot be excluded. Whole-rock isochrons for the IIAB and IIIAB groups are statistically indistinguishable. Pooled data yield an initial 187Os 186Os of 0.794 ?? 0.010, with a slope of (7.92 ?? 0.20) ?? 10-2 corresponding to a magmatic iron meteorite age of 4.65 ?? 0.11 Ga (using a decay constant of 1.64 ?? 10-11 a-1). Given the errors in the slope and half life, this age does not differ significantly from the canonical chondrite age of 4.56 Ga, but could be as young as 4.46 Ga. ?? 1992.

  18. Xenon, osmium, and lead formed in O-shells and C-shells of massive stars

    NASA Technical Reports Server (NTRS)

    Heymann, D.; Dziczkaniec, M.

    1980-01-01

    In this paper it is shown that the explosive products from O-shells of massive stars which contain Xe-124 with large overproduction factors do not contain any of the naturally occurring isotopes of Os and Pb. Further, it is shown that the explosive products from C-shells (explosive carbon burning) do contain Os and Pb along with Xe which is strongly enriched in r-Xe of anomalous isotopic composition. The composition of Os in this matter is probably s-like rather than r-like. Pb in this matter is enriched in Pb-208. The results and arguments of this paper have implications for studies of isotopic compositions of Xe, Os, and Pb in residues of the Allende and other carbonaceous chondrites.

  19. The Osmium Isotopic Composition of Tagish Lake and Other Chondrites, Implications for Late Terrestrial Planetary Accretion

    NASA Technical Reports Server (NTRS)

    Brandon, A. D.

    2003-01-01

    The goals of this investigation are twofold. First, obtain high-precision Os isotope measurements of Tagish Lake and other chondrites by TIMS. Second, measure Re, Os, Pt, and other HSE concentrations by isotope dilution using TIMS and ICPMS. These measurements will determine whether this meteorite does in fact represent C-chondrite material with timeintegrated elevated Re/Os and Pt/Os with the implications to late accretion material characteristics.

  20. Rhenium-osmium and samarium-neodymium isotopic systematics of the Stillwater complex

    NASA Technical Reports Server (NTRS)

    Lambert, David D.; Shirey, Steven B.; Carlson, Richard W.; Morgan, John W.; Walker, Richard J.

    1989-01-01

    The role of magma mixing in the formation of strategic platinum-group element ore deposits is examined using isotopic data from the Stillwater Complex, Montana. Nd and Os isotopic data show that the intrusion formed from at least two distinct magmas: ultramafic (U-type) affinity magmas and anorthositic (A-type) affinity magmas. The U-type magmas formed from a lithospheric mantle source containing recycled crustal materials and the A-type magmas originated either by crustal contamination of basaltic magmas or by partial melting of basalt in the lower crust. The results also suggest that the platinum-group element ore deposits were derived from A-type magmas which were injected into the U-type magma chamber at several stages during the development of the ultramafic series.