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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. 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.

  11. 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.

  12. 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.

  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. 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.

  7. 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.

  8. 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.

  9. 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

  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. 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

  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. 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.

  1. 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

  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. 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

  9. 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.

  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

    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.

  12. 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.

  13. 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.

  14. 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

  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. 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.

  18. 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.

  19. 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.

  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

    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

  2. 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

  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. 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

  6. 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.

  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. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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

  14. 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.

  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. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  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. 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

  8. 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

  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. 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.

  15. 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.

  16. 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

  17. 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

  18. 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

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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

  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. 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

  15. 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

  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. 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

  20. 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

  1. 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

  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. 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

  8. 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

  9. 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

  10. 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

  11. 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.

  12. 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

  13. 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

  14. 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.

  15. 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.

  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. 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

  19. 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

  20. 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

  1. 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

  2. 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

  3. 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

  4. 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.

  5. 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).

  6. 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

  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. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  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. 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.

  6. 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.

  7. 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.

  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. 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

  11. 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

  12. 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.

  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. 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

  16. 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}.

  17. 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.

  18. 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

  19. 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.

  20. 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

  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. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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).

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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