Study of fine structure of deformed hafnium

International Nuclear Information System (INIS)

Voskresenskaya, L.A.; Petukhova, A.S.; Kovalev, K.S.

1978-01-01

Variations in the hafnium fine structure following the cold plastic deformation have been studied. The fine structure condition has been studied through the harmonic analysis of the profile of the X-ray diffraction line, obtained at the DRON-I installation. Received has been the dependence of the crystal lattice microdistortions value on the deformation extent for hafnium. This dependence is compared with the corresponding one for zirconium. It is found out that at all the deformations the microdistortion distribution is uniform. The microdistortion value grows with the increase in the compression. During the mechanical impact higher microdistortions of the crystal lattice occur in the hafnium rather than in zirconium

Properties of filmogen solutions and films of hafnium compounds

International Nuclear Information System (INIS)

Sviridova, A.I.

1986-01-01

Study on hafnium hydrolizing compound solutions, used for hafnium oxide homogeneous layer formation, is conducted. In particular, electric conductivity, acidity and refractive index were investigated depending on the sal on ether concentration and the storage time. Oxyhafnium nitrate, hafnium chloride in ethanol, dichlorodiethoxyhafnium, hafnium oxychloride were used as initial compounds. Hydrolysis of hafnium compounds in solution occurs partially; further process occurs in the thin layer on the optical element surface; final decomposition is performed under heat treatment. It is ascertained, that alcoholic-aqueous solutions of inorganic salts can be filmogen only at definite acidity, density and viscosity (1.33-2.5 cp.). It is also ascertained that refractive index values and transmission spectral boundary of coatings, produced from alkoxy compound solutions and from chloride salt solutions, are practically the same. Transmittance boundary in ultraviolet region of spectrum of oxide films produced from nitrate and chloride solutions, varies with the heating temperature increase differently

Investigation of ferromagnetism in oxygen deficient hafnium oxide thin films

Energy Technology Data Exchange (ETDEWEB)

Hildebrandt, Erwin; Kurian, Jose; Krockenberger, Yoshiharu; Alff, Lambert [Institut fuer Materialwissenschaft, TU Darmstadt (Germany); Suter, Andreas [PSI, Villingen (Switzerland); Wilhelm, Fabrice; Rogalev, Andrei [ESRF, Grenoble (France)

2008-07-01

Oxygen deficient thin films of hafnium oxide were grown on single crystal r-cut and c-cut sapphire by reactive molecular beam epitaxy. RF-activated oxygen was used for the in situ oxidation of hafnium oxide thin films. Oxidation conditions were varied substantially in order to create oxygen deficiency in hafnium oxide films intentionally. The films were characterized by X-ray and magnetic measurements. X-ray diffraction studies show an increase in lattice parameter with increasing oxygen deficiency. Oxygen deficient hafnium oxide thin films also showed a decreasing bandgap with increase in oxygen deficiency. The magnetisation studies carried out with SQUID did not show any sign of ferromagnetism in the whole oxygen deficiency range. X-ray magnetic circular dichroism measurements also confirmed the absence of ferromagnetism in oxygen deficient hafnium oxide thin films.

Titanium zirconium and hafnium coordination compounds with vanillin thiosemicarbazone

International Nuclear Information System (INIS)

Konunova, Ts.B.; Kudritskaya, S.A.

1987-01-01

Coordination compounds of titanium zirconium and hafnium tetrachlorides with vanillin thiosemicarbazone of MCl 4 x nLig composition, where n=1.5, 4 for titanium and 1, 2, 4 for zirconium and hafnium, are synthesized. Molar conductivity of ethanol solutions is measured; IR spectroscopic and thermochemical investigation are carried out. The supposition about ligand coordination via sulfur and azomethine nitrogen atoms is made. In all cases hafnium forms stable compounds than zirconium

Hafnium - material for chemical apparatus engineering

International Nuclear Information System (INIS)

Jennert, D.

1981-01-01

This work describes - on the background of available literature - the properties of hafnium in technical quality (DIN-material No. 2.6400) as material for chemical apparatus engineering. The occurence, refining, physical and chemical properties will be described as well as the material behavior. In conclusion, it has been found that there is, at present, sufficient information for the engineering of hafnium which has to be completed by additional investigations for special applications. (orig.) [de

Internal Dosimetry for Inhalation of Hafnium Tritide Aerosols

Energy Technology Data Exchange (ETDEWEB)

Inkret, W.C.T.; Schillaci, M.E.; Boyce, M.K.; Cheng, Y.S.; Efurd, D.W.; Little, T.T.; Miller, G.; Musgrave, J.A.; Wermer, J.R

2001-07-01

Metal tritides with low dissolution rates may have residence times in the lungs which are considerably longer than the biological half-time normally associated with tritium in body water, resulting in long-term irradiation of the lungs by low energy {beta} particles and bremsstrahlung X rays. Samples of hafnium tritide were placed in a lung simulant fluid to determine approximate lung dissolution rates. Hafnium hydride samples were analysed for particle size distribution with a scanning electron microscope. Lung simulant data indicated a biological dissolution half-time for hafnium tritide on the order of 10{sup 5}d. Hafnium hydride particle sizes ranged between 2 and 10 {mu}m, corresponding to activity median aerodynamic diameters of 5 to 25 {mu}m. Review of in vitro dissolution data, development of a biokinetic model, and determination of secondary limits for 1 {mu}m AMAD particles are presented and discussed. (author)

Titanium(IV), zirconium, hafnium and thorium

International Nuclear Information System (INIS)

Brown, Paul L.; Ekberg, Christian

2016-01-01

Titanium can exist in solution in a number of oxidation states. The titanium(IV) exists in acidic solutions as the oxo-cation, TiO 2+ , rather than Ti 4+ . Zirconium is used in the ceramics industry and in nuclear industry as a cladding material in reactors where its reactivity towards hydrolysis reactions and precipitation of oxides may result in degradation of the cladding. In nature, hafnium is found together with zirconium and as a consequence of the contraction in ionic radii that occurs due to the 4f -electron shell, the ionic radius of hafnium is almost identical to that of zirconium. All isotopes of thorium are radioactive and, as a consequence of it being fertile, thorium is important in the nuclear fuel cycle. The polymeric hydrolysis species that have been reported for thorium are somewhat different to those identified for zirconium and hafnium, although thorium does form the Th 4 (OH) 8 8+ species.

Ferroelectricity in undoped hafnium oxide

International Nuclear Information System (INIS)

Polakowski, Patrick; Müller, Johannes

2015-01-01

We report the observation of ferroelectric characteristics in undoped hafnium oxide thin films in a thickness range of 4–20 nm. The undoped films were fabricated using atomic layer deposition (ALD) and embedded into titanium nitride based metal-insulator-metal (MIM) capacitors for electrical evaluation. Structural as well as electrical evidence for the appearance of a ferroelectric phase in pure hafnium oxide was collected with respect to film thickness and thermal budget applied during titanium nitride electrode formation. Using grazing incidence X-Ray diffraction (GIXRD) analysis, we observed an enhanced suppression of the monoclinic phase fraction in favor of an orthorhombic, potentially, ferroelectric phase with decreasing thickness/grain size and for a titanium nitride electrode formation below crystallization temperature. The electrical presence of ferroelectricity was confirmed using polarization measurements. A remanent polarization P r of up to 10 μC cm −2 as well as a read/write endurance of 1.6 × 10 5 cycles was measured for the pure oxide. The experimental results reported here strongly support the intrinsic nature of the ferroelectric phase in hafnium oxide and expand its applicability beyond the doped systems

Hafnium-Based Contrast Agents for X-ray Computed Tomography.

Science.gov (United States)

Berger, Markus; Bauser, Marcus; Frenzel, Thomas; Hilger, Christoph Stephan; Jost, Gregor; Lauria, Silvia; Morgenstern, Bernd; Neis, Christian; Pietsch, Hubertus; Sülzle, Detlev; Hegetschweiler, Kaspar

2017-05-15

Heavy-metal-based contrast agents (CAs) offer enhanced X-ray absorption for X-ray computed tomography (CT) compared to the currently used iodinated CAs. We report the discovery of new lanthanide and hafnium azainositol complexes and their optimization with respect to high water solubility and stability. Our efforts culminated in the synthesis of BAY-576, an uncharged hafnium complex with 3:2 stoichiometry and broken complex symmetry. The superior properties of this asymmetrically substituted hafnium CA were demonstrated by a CT angiography study in rabbits that revealed excellent signal contrast enhancement.

40 CFR 471.90 - Applicability; description of the zirconium-hafnium forming subcategory.

Science.gov (United States)

2010-07-01

... zirconium-hafnium forming subcategory. 471.90 Section 471.90 Protection of Environment ENVIRONMENTAL... POINT SOURCE CATEGORY Zirconium-Hafnium Forming Subcategory § 471.90 Applicability; description of the zirconium-hafnium forming subcategory. This subpart applies to discharges of pollutants to waters of the...

Calorimetric measurements on hafnium titanate

International Nuclear Information System (INIS)

Kandan, R.; Prabhakara Reddy, B.; Panneerselvam, G.; Nagarajan, K.

2012-01-01

Owing to its desirable nuclear and mechanical properties such as good absorption cross-section for thermal neutrons (105 barns), hafnium titanate (HfTiO 4 ) finds application as control rods for nuclear reactors. An accurate knowledge of the thermo physical properties of this material is necessary for design of control rod and for modeling its performance. Heat capacity is an important thermodynamic property that determines the temperature dependent variation of all other thermodynamic properties. Hence enthalpy increments of hafnium titanate (HfTiO 4 ) were measured in the temperature range 803-1663 K by employing the method of inverse drop calorimetry using high temperature differential calorimeter

Preparation of complexes of zirconium and hafnium tetrachlorides with phosphorus oxychloride

International Nuclear Information System (INIS)

Snyder, T.S.; Stoltz, R.A.

1989-01-01

This patent describes an improvement in a method for separating hafnium chloride from zirconium chloride using a distillation column, with a hafnium chloride enriched vapor stream taken from the top of the column and a zirconium enriched chloride stream taken from the bottom of the column. The improvement comprising: purifying the zirconium-hafnium chloride in a molten salt purification vessel prior to or after introduction into the distillation column to substantially eliminate iron chloride from the zirconium-hafnium chloride by at least periodically removing iron chloride from the molten salt purification vessel by electrochemically plating iron onto an electrode in the molten salt purification vessel. The molten salt in the molten salt purification vessel consisting essentially of a mixture of chlorides selected from the group consisting of alkali metals, alkaline earth metals, zirconium, hafnium, aluminum, manganese, and zinc

Method of purifying zirconium tetrachloride and hafnium tetrachloride in a vapor stream

International Nuclear Information System (INIS)

Snyder, T.S.; Stolz, R.A.

1992-01-01

This patent describes a method of purifying zirconium tetrachloride and hafnium tetrachloride in a vapor stream from a sand chlorinator in which the silicon and metals present in sand fed to the chlorinator are converted to chlorides at temperatures over about 800 degrees C. It comprises cooling a vapor stream from a sand chlorinator, the vapor stream containing principally silicon tetrachloride, zirconium tetrachloride, and hafnium tetrachloride contaminated with ferric chloride, to a temperature of from about 335 degrees C to about 600 degrees C; flowing the vapor stream through a gaseous diffusion separative barrier to produce a silicon tetrachloride-containing vapor stream concentrated in zirconium tetrachloride and hafnium tetrachloride and a silicon tetrachloride-containing vapor stream depleted in zirconium tetrachloride and hafnium tetrachloride; adsorbing the ferric chloride in the separative barrier; and recovering the silicon tetrachloride stream concentrated in zirconium tetrachloride and hafnium tetrachloride separately from the silicon tetrachloride stream depleted in zirconium tetrachloride and hafnium tetrachloride

Spectrofluorimetric determination of hafnium and zirconium with 3,7-dihydroxyflavone

Energy Technology Data Exchange (ETDEWEB)

Ito, Takushi; Suzuki, Osamu; Seuzuki, Tetsuo; Murata, Akira

1986-04-01

The absorptive and fluorescent characteristics of the hafnium and zirconium complexes of 3-hydroxyflavone and its 12 hydroxy and methoxy derivatives have been studied. The fluorescence of the 1:1 hafnium - 3,7-dihydroxyflavone complex (lambdasub(ex.)397 nm,lambdasub(em.) 465 nm) in 3 M hydrochloric acid has been used to determine 2-40 ng ml/sup -1/ of hafnium. The fluorescence of the 1:1 zirconium - 3,7-dihydroxyflavone complex (lambdasub(ex.) 395 nm, lambda sub(em.) 465 nm) at pH 2.0 in 0.02 M sulphate solution has been used to determine 2-40 ng ml/sup -1/ of zirconium. These methods are very sensitive and can be used for the simultaneous determination of hafnium and zirconium with an error of about 5%.

Molten salt extractive distillation process for zirconium-hafnium separation

International Nuclear Information System (INIS)

McLaughlin, D.F.; Stoltz, R.A.

1989-01-01

This patent describes an improvement in a process for zirconium-hafnium separation. It utilizes an extractive distillation column with a mixture of zirconium and hafnium tetrachlorides introduced into a distillation column having a top and bottom with hafnium enriched overheads taken from the top of the column and a molten salt solvent circulated through the column to provide a liquid phase, and with molten salt solvent containing zirconium chloride being taken from the bottom of the distillation column. The improvements comprising: utilizing a molten salt solvent consisting principally of lithium chloride and at least one of sodium, potassium, magnesium and calcium chlorides; stripping of the zirconium chloride taken from the bottom of the distillation column by electrochemically reducing zirconium from the molten salt solvent; and utilizing a pressurized reflux condenser on the top of the column to add the hafnium chloride enriched overheads to the molten salt solvent previously stripped of zirconium chloride

40 CFR 421.330 - Applicability: Description of the primary zirconium and hafnium subcategory.

Science.gov (United States)

2010-07-01

... primary zirconium and hafnium subcategory. 421.330 Section 421.330 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Zirconium and Hafnium Subcategory § 421.330 Applicability: Description of the primary zirconium and hafnium subcategory. The provisions of this subpart are applicable to discharges resulting...

Design and fabrication of hafnium tube to control the power of the irradiation test fuel in HANARO

Energy Technology Data Exchange (ETDEWEB)

Kim, D. H.; Lee, C. B.; Kim, Y. M.; Yang, Y. S.; Jung, Y. H

2003-05-01

For the irradiation test at HANARO, non-instrumentation capsule was manufactured and hafnium tube was used to control LHGR of HANARO. Hafnium tube can control the irradiation condition of HANARO similar to that of commercial reactor. Hafnium tube thickness was determined by the LHGR calculated at OR-4 irradiation hole to be installed the non-instrumented capsule. To fabricate the hafnium tube with hafnium plate, the fabrication method was determined by using the hafnium mechanical properties. And the tensile strength of hafnium was confirmed by tensile test. This report is confirmed the LHGR control at the OR-4 and the Hafnium fabrication for in used which the AFPCAP non-instrumented irradiation capsule.

Use of X-ray fluorescence analysis for the determination of hafnium in zircalloys

International Nuclear Information System (INIS)

Sato, I.M.; Salvador, V.L.R.; Lordello, A.R.

1985-01-01

The determination of hafnium at trace levels (ppm) in the presence of zirconium by X-ray fluorescence technique is presented. The samples were prepared in the form of double-layer pellets, with boric acid as the binding material. The most sensitive first order line of hafnium HfLα (0.157 nm), which is used analyticaly, has approximately 67% overlapping with second order line of zirconium ZrKα 1 , (0.079 nm). As the excitation potencial of zirconium is larger than hafnium, the best condition was selected, so that the interference of zirconium intensity would not be significant in hafnium analytical line. The method allowed the determination of hafnium above 5.0 ppm (LLd = 1.5 ppm) with an accuracy of less than 10%. (Author) [pt

Use of hafnium in control bars of nuclear reactors

International Nuclear Information System (INIS)

Ramirez S, J.R.; Alonso V, G.

2003-01-01

Recently the use of hafnium as neutron absorber material in nuclear reactors has been reason of investigation by virtue of that this material has nuclear properties as to the neutrons absorption and structural that can prolong the useful life of the control mechanisms of the nuclear reactors. In this work some of those more significant hafnium properties are presented like nuclear material. Also there are presented calculations carried out with the HELIOS code for fuel cells of uranium oxide and of uranium and plutonium mixed oxides under controlled conditions with conventional bars of boron carbide and also with similar bars to which are substituted the absorbent material by metallic hafnium, the results are presented in this work. (Author)

The corrosion behavior of hafnium in high-temperature-water environments

Energy Technology Data Exchange (ETDEWEB)

Rishel, D.M.; Smee, J.D.; Kammenzind, B.F.

1999-10-01

The high-temperature-water corrosion performance of hafnium is evaluated. Corrosion kinetic data are used to develop correlations that are a function of time and temperature. The evaluation is based on corrosion tests conducted in out-of-pile autoclaves and in out-of-flux locations of the Advanced Test Reactor (ATR) at temperatures ranging from 288 to 360 C. Similar to the corrosion behavior of unalloyed zirconium, the high-temperature-water corrosion response of hafnium exhibits three corrosion regimes: pretransition, posttransition, and spalling. In the pretransition regime, cubic corrosion kinetics are exhibited, whereas in the posttransition regime, linear corrosion kinetics are exhibited. Because of the scatter in the spalling regime data, it is not reasonable to use a best fit of the data to describe spalling regime corrosion. Data also show that neutron irradiation does not alter the corrosion performance of hafnium. Finally, the data illustrate that the corrosion rate of hafnium is significantly less than that of Zircaloy-2 and Zircaloy-4.

Corrosion potentials of hafnium in molten alkaline-earth metal chlorides

International Nuclear Information System (INIS)

Kovalik, O.Yu.; Tkhaj, V.D.

2000-01-01

Corrosion potentials of hafnium in molten calcium, strontium and barium chlorides are measured and their temperature dependences are determined. It is stated that the corrosion potential of hafnium becomes more electropositive with an increase of the environment temperature. If the temperature is the same the potential shifts to the interval of more electronegative values in the row of CaCl 2 , SrCl 2 , BaCl 2 which corresponds to a lesser corrosion rate in environments positioned from left to right. the comparison of hafnium corrosion potentials with previously measured values for titanium and zirconium shows that a metal activity decrease results in a more electronegative corrosion potential [ru

Electronic structure of pentacene on hafnium studied by ultraviolet photoelectron spectroscopy

International Nuclear Information System (INIS)

Kang, Seong Jun; Yi, Yeon Jin; Kim, Chung Yi; Whang, Chung Nam

2005-01-01

The electronic structure of pentacene on hafnium, which is a low work function metal, was analyzed by using ultraviolet photoelectron spectroscopy. The energy level alignment was studied by using the onset of the highest occupied molecular orbital level and the shift of the vacuum level of the pentacene layer, which was deposited on a clean hafnium surface in a stepwise manner. The measured onset of the highest occupied molecular orbital energy level was 1.52 eV from the Fermi level of hafnium. The vacuum level was shifted 0.28 eV toward higher binding energy with additional pentacene layers, which means an interfacial dipole exists at the interface between pentacene and hafnium. We confirm that a small electron injection barrier can be achieved by inserting a low work function metal in a pentacene thin-film transistor.

Synthesis of Hafnium-Based Ceramic Materials for Ultra-High Temperature Aerospace Applications

Science.gov (United States)

Johnson, Sylvia; Feldman, Jay

2004-01-01

This project involved the synthesis of hafnium (Hf)-based ceramic powders and Hf-based precursor solutions that were suitable for preparation of Hf-based ceramics. The Hf-based ceramic materials of interest in this project were hafnium carbide (with nominal composition HE) and hafnium dioxide (HfO2). The materials were prepared at Georgia Institute of Technology and then supplied to research collaborators Dr. Sylvia Johnson and Dr. Jay Feldman) at NASA Ames Research Center.

Application of hafnium hydride control rod to large sodium cooled fast breeder reactor

Energy Technology Data Exchange (ETDEWEB)

Ikeda, Kazumi, E-mail: kazumi_ikeda@mfbr.mhi.co.jp [Mitsubishi FBR Systems, Inc., 34-17, Jingumae 2-Chome, Shibuya-ku, Tokyo 150-0001 (Japan); Moriwaki, Hiroyuki, E-mail: hiroyuki_moriwaki@mfbr.mhi.co.jp [Mitsubishi FBR Systems, Inc., 34-17, Jingumae 2-Chome, Shibuya-ku, Tokyo 150-0001 (Japan); Ohkubo, Yoshiyuki, E-mail: yoshiyuki_okubo@mfbr.mhi.co.jp [Mitsubishi FBR Systems, Inc., 34-17, Jingumae 2-Chome, Shibuya-ku, Tokyo 150-0001 (Japan); Iwasaki, Tomohiko, E-mail: tomohiko.iwasaki@qse.tohoku.ac.jp [Department of Quantum Science and Energy Engineering, Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai-shi, Miyagi-ken 980-8579 (Japan); Konashi, Kenji, E-mail: konashi@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, Narita-cho, Oarai-machi, Higashi-Ibaraki-gun, Ibaraki-ken 311-1313 (Japan)

2014-10-15

Highlights: • Application of hafnium hydride control rod to large sodium cooled fast breeder reactor. • This paper treats application of an innovative hafnium hydride control rod to a large sodium cooled fast breeder reactor. • Hydrogen absorption triples the reactivity worth by neutron spectrum shift at H/Hf ratio of 1.3. • Lifetime of the control rod quadruples because produced daughters of hafnium isotopes are absorbers. • Nuclear and thermal hydraulic characteristics of the reactor are as good as or better than B-10 enriched boron carbide. - Abstract: This study treats the feasibility of long-lived hafnium hydride control rod in a large sodium-cooled fast breeder reactor by nuclear and thermal analyses. According to the nuclear calculations, it is found that hydrogen absorption of hafnium triples the reactivity by the neutron spectrum shift at the H/Hf ratio of 1.3, and a hafnium transmutation mechanism that produced daughters are absorbers quadruples the lifetime due to a low incineration rate of absorbing nuclides under irradiation. That is to say, the control rod can function well for a long time because an irradiation of 2400 EFPD reduces the reactivity by only 4%. The calculation also reveals that the hafnium hydride control rod can apply to the reactor in that nuclear and thermal characteristics become as good as or better than 80% B-10 enriched boron carbide. For example, the maximum linear heat rate becomes 3% lower. Owing to the better power distribution, the required flow rate decreases approximately by 1%. Consequently, it is concluded on desk analyses that the long lived hafnium hydride control rod is feasible in the large sodium-cooled fast breeder reactor.

X-Ray Photoemission Study of the Oxidation of Hafnium

International Nuclear Information System (INIS)

Chourasia, R.; Hickman, J.L.; Miller, R.L.; Nixon, G.A.; Seabolt, M.A.

2011-01-01

About 20 angstrom of hafnium were deposited on silicon substrates using the electron beam evaporation technique. Two types of samples were investigated. In one type, the substrate was kept at the ambient temperature. After the deposition, the substrate temperature was increased to 100, 200, and 300 degree C. In the other type, the substrate temperature was held fixed at some value during the deposition. For this type, the substrate temperatures used were 100, 200, 300, 400, 500, 550, and 600 degree C. The samples were characterized in situ by the technique of X-ray photoelectron spectroscopy. No trace of elemental hafnium is observed in the deposited overlayer. Also, there is no evidence of any chemical reactivity between the overlayer and the silicon substrate over the temperature range used. The hafnium overlayer shows a mixture of the dioxide and the suboxide. The ratio of the suboxide to dioxide is observed to be more in the first type of samples. The spectral data indicate that hafnium has a strong affinity for oxygen. The overlayer gets completely oxidized to form HfO 2 at substrate temperature around 300 degree C for the first type of samples and at substrate temperature greater than 550 degree C for the second type

X-Ray Photoemission Study of the Oxidation of Hafnium

Directory of Open Access Journals (Sweden)

A. R. Chourasia

2009-01-01

Full Text Available About 20 Å of hafnium were deposited on silicon substrates using the electron beam evaporation technique. Two types of samples were investigated. In one type, the substrate was kept at the ambient temperature. After the deposition, the substrate temperature was increased to 100, 200, and 300∘C. In the other type, the substrate temperature was held fixed at some value during the deposition. For this type, the substrate temperatures used were 100, 200, 300, 400, 500, 550, and 600∘C. The samples were characterized in situ by the technique of X-ray photoelectron spectroscopy. No trace of elemental hafnium is observed in the deposited overlayer. Also, there is no evidence of any chemical reactivity between the overlayer and the silicon substrate over the temperature range used. The hafnium overlayer shows a mixture of the dioxide and the suboxide. The ratio of the suboxide to dioxide is observed to be more in the first type of samples. The spectral data indicate that hafnium has a strong affinity for oxygen. The overlayer gets completely oxidized to form HfO2 at substrate temperature around 300∘C for the first type of samples and at substrate temperature greater than 550∘C for the second type.

High temperature diffusion of hafnium in tungsten and a tungsten-hafnium carbide alloy

International Nuclear Information System (INIS)

Ozaki, Y.; Zee, R.H.

1994-01-01

Refractory metals and ceramics are used extensively in energy systems due to their high temperature properties. This is particularly important in direct conversion systems where thermal to electric conversion efficiency is a direct function of temperature. Tungsten, which has the highest melting temperature among elemental metals, does not possess sufficient creep resistance at temperature above 1,600 K. Different dispersion strengthened tungsten alloys have been developed to extend the usefulness of tungsten to higher temperatures. One of these alloys, tungsten with 0.4 mole percent of finely dispersed HfC particles (W-HfC), has the optimum properties for high temperature applications. Hafnium carbide is used as the strengthening agent due to its high chemical stability and its compatibility with tungsten. The presence of HfC particles retards the rate of grain growth as well as restricting dislocation motion. Both of which are beneficial for creep resistance. The long term behavior of this alloy depends largely on the evolution of its microstructure which is governed by the diffusion of its constituents. Data on the diffusion of carbon in tungsten and tungsten self-diffusion are available, but no direct measurements have been made on the diffusion of hafnium in tungsten. The only diffusion data available are estimated from a coarsening study and these data are highly unreliable. In this study, the diffusion behavior of hafnium in pure tungsten and in a W-HfC alloy was directly measured by means of Secondary Ion Mass Spectroscopy (SIMS). The selection of the W-HfC alloy is due to its importance in high temperature engineering applications, and its higher recrystallization temperature. The presence of HfC particles in tungsten restricts grain growth resulting in better high temperature creep resistance. The higher recrystallization temperature allows measurements to be made over a wider range of temperatures at a relatively constant grain size

Decay of mass-separated 187Au (8.4 min) to 187Pt

International Nuclear Information System (INIS)

Gnade, B.E.; Fink, R.W.; Wood, J.L.

1983-01-01

The decay of 187 Au to 187 Pt has been studied with mass-separated sources from the UNISOR facility. Multiscaled spectra of γ-rays, X-rays, and conversion electrons, as well as γγt, Xγt, eγt, and eXt coincidences were obtained. The half-life of the 187 Au ground state was measured to be 8.4 +- 0.3 min. A decay scheme has been constructed incorporating 88% of the decay intensity assigned to 187 Au. The isub(13/2) band in 187 Pt is populated through low-spin band members. The levels at 260 and 288 keV are found to de-excite by EO transitions. From a γ-ray-gated K/β + ratio, the β-decay energy of 8.4 min 187 Au is deduced to be Qsub(EC)=3.90 +- 0.15 MeV. The positive-parity states in 187 Pt are compared with calculations made using the Nilsson model with a triaxial degree of freedom. The possibility that shape coexistence is present at low energy in 187 Pt is discussed. (orig.)

Elaboration and characterisation of yttrium oxide and hafnium oxide powders by the sol-gel process

International Nuclear Information System (INIS)

Hours, T.

1988-01-01

The two classical sol-gel processes, colloidal and polymeric are studied for the preparation of yttrium oxide and hafnium oxide high performance powders. In the colloidal process, controlled and reproducible conditions for the preparation of yttrium oxide and hafnium oxide sols from salts or alkoxides are developed and the hydrothermal synthesis monodisperse hafnium oxide colloids is studied. The polymeric process is studied with hafnium ethyl-hexylate, hydrolysis kinetics for controlled preparation of sols and gels is investigated. Each step of preparation is detailed and powders obtained are characterized [fr

Modelling of Zirconium and Hafnium separation using continuous annular chromatography

International Nuclear Information System (INIS)

Moch-Setyadji; Endang Susiantini

2014-01-01

Nuclear degrees of zirconium in the form of a metal alloy is the main material for fuel cladding of NPP. Zirconium is also used as sheathing UO 2 kernel in the form of ZrC as a substitute of SiC in the fuel elements of High Temperature Reactor (HTR). Difficulty separating hafnium from zirconium because it has a lot of similarities in the chemical properties of Zr and Hf. Annular chromatography is a device that can be used for separating of zirconium and hafnium to obtain zirconium nuclear grade. Therefore, it is necessary to construct the mathematical modelling that can describe the separation of zirconium and hafnium in the annular chromatography containing anion resin dowex-1X8. The aim of research is to perform separation simulation by using the equilibrium model and mass transfer coefficient resulted from research. Zr and Hf feed used in this research were 26 and 1 g/l, respectively. Height of resin (L), angular velocity (ω) and the superficial flow rate (uz) was varied to determine the effect of each parameter on the separation of Zr and Hf. By using Kd and Dv values resulted previous research. Simulation results showed that zirconium and hafnium can be separated using a continuous annular chromatography with high resin (long bed) 50 cm, superficial flow rate of 0.001 cm/s, the rotation speed of 0.006 rad/min and 20 cm diameter annular. In these conditions the results obtained zirconium concentration of 10,303.226 g/m 3 and hafnium concentration of 12.324 g/m 3 (ppm). (author)

Joint titrimetric determination of zirconium and hafnium

International Nuclear Information System (INIS)

Vazquez, Cristina; Botbol, Moises; Bianco de Salas, G.N.; Cornell de Casas, M.I.

1980-01-01

A method for the joint titrimetric determination of zirconium and hafnium, which are elements of similar chemical behaviour, is described. The disodic salt of the ethylendiaminetetracetic acid (EDTA) is used for titration, while xilenol orange serves as final point indicator. Prior to titration it is important to evaporate with sulfuric acid, the solution resulting from the zirconium depolymerization process, to adjust the acidity and to eliminate any interferences. The method, that allows the quick and precise determination of zirconium and hafnium in quantities comprised between 0.01 and mg, was applied to the analysis of raw materials and of intermediate and final products in the fabrication of zirconium sponge and zircaloy. (M.E.L.) [es

Compositional characterization of hafnium alloy used as control rod material in nuclear reactor

International Nuclear Information System (INIS)

Sharma, P.K.; Bassan, M.K.T.; Avhad, D.K.; Singhal, R.K.

2014-01-01

Hafnium (Hf) is a heavy, steel-gray metal in the reactive metals group that is very closely related to zirconium (Zr) and forms a continuous solid-solution at all concentrations of zirconium and hafnium. Hafnium occurs naturally with zirconium at a ratio of approximately 1:50 and is produced exclusively as a co-product of nuclear-grade zirconium. It is used in a variety of applications where few substitutes are available. Thus with its relatively high thermal neutron absorption cross-section, hafnium's biggest application is as control rod material in nuclear reactors. During this work, major (Zirconium (Zr), Cobalt (Co) and Molybdenum (Mo)) and trace ((Iron (Fe), Nickel (Ni) and Titanium (Ti)) elements were measured in the bulk matrices of Hf. These materials are also associated with other impurities such as O, N, H etc.

Shape coexistence near the Z-82 closed shell: a study of the excited states of 187Au and 187Pt in the β+ decay of 187Hg and 187Au

International Nuclear Information System (INIS)

Grimm, M.A. Jr.

1978-11-01

The decays of mass-separated (2.4, 2.2 min)/sup 187m,g/Hg and (8.4 min) 187 Au were studied. Both high- and low-spin states in 187 Au are fed in the (β + , EC) decay of /sup 187m,g/Hg isomers. The h/sub 11/2/, h/sub 9/2/, s/sub 1/2/, d/sub 3/2/, and d/sub 5/2/ collective bands, which are systematically observed throughout the odd-mass gold isotopes, are now extended to 187 Au. In 187 Au, the h/sub 9/2/ bandhead is below the h/sub 11/2/ bandhead, and the transition between the two is found to proceed via a hindered M1 transition due to the change in nuclear shape involved in the transition. One of the most important results of the present study is the discovery of the coupling of the odd proton in an h/sub 9/2/ particle state to the excited O + state of the 186 Pt core. Only the low spin states in 187 Pt appear to be populated in the beta decay of 187 Au. The nature of these low-spin states is not understood at present. One aspect of the levels of 187 Pt not previously reported is a delayed transition of 251 keV energy observed in the present study. 111 references

Bond formation in hafnium atom implantation into SiC induced by high-energy electron irradiation

International Nuclear Information System (INIS)

Yasuda, H.; Mori, H.; Sakata, T.; Naka, M.; Fujita, H.

1992-01-01

Bilayer films of Hf (target atoms)/α-SiC (substrate) were irradiated with 2 MeV electrons in an ultra-high voltage electron microscope (UHVEM), with the electron beam incident on the hafnium layer. As a result of the irradiation, hafnium atoms were implanted into the SiC substrate. Changes in the microstructure and valence electronic states associated with the implantation were studied by a combination of UHVEM and Auger valence electron spectroscopy. The implantation process is summarized as follows. (1) Irradiation with 2 MeV electrons first induces a crystalline-to-amorphous transition in α-SiC. (2) Hafnium atoms which have been knocked-off from the hafnium layer by collision with the 2 MeV electrons are implanted into the resultant amorphous SiC. (3) The implanted hafnium atoms make preferential bonding to carbon atoms. (4) With continued irradiation, the hafnium atoms repeat the displacement along the beam direction and the subsequent bonding with the dangling hybrids of carbon and silicon. The repetition of the displacement and subsequent bonding lead to the deep implantation of hafnium atoms into the SiC substrate. It is concluded that implantation successfully occurs when the bond strength between a constituent atom of a substrate and an injected atom is stronger than that between constituent atoms of a substrate. (Author)

Hafnium Resonance Parameter Analysis Using Neutron Capture and Transmission Experiments

International Nuclear Information System (INIS)

MJ Trbovich; DP Barry; RE Slovacck; Y Danon; RC Block; JA Burke; NJ Drindak; G Leinweber; RV Ballad

2004-01-01

The focus of this work is to determine resonance parameters for stable hafnium isotopes in the 0.005-200 eV region, with special emphasis on the overlapping 176 Hf and 178 Hf resonances near 8 eV. The large neutron cross section of hafnium, combined with its corrosion resistance and excellent mechanical properties, make it a useful material for controlling nuclear reactions. Experiments measuring neutron capture and transmission were performed at the Rensselaer Polytechnic Institute (RPI) electron linear accelerator (LINAC) using the time of flight method. 6 Li glass scintillation detectors were used for transmission experiments at flight path lengths of 15 and 25 m. Capture experiments were done using a sixteen section NaI(Tl) multiplicity detector at a flight path length of 25 m. These experiments utilized various thicknesses of metallic and isotopically-enriched liquid samples. The liquid samples were designed to provide information on the 176 Hf and 178 Hf contributions to the 8 eV doublet without saturation. Data analysis was done using the R-matrix Bayesian code SAMMY version M6 beta. SAMMY is able to account for experimental resolution effects for each of the experimental setups at the RPI LINAC, and also can correct for multiple scattering effects in neutron capture yield data. The combined capture and transmission data analysis yielded resonance parameters for all hafnium isotopes from 0.005-200 eV. Resonance integrals were calculated along with errors for each hafnium isotope using the NJOY [1] and INTER [2] codes. The isotopic resonance integrals calculated were significantly different than previously published values; however the calculated elemental hafnium resonance integral changed very little

Zirconium and hafnium in the southeastern Atlantic States

Science.gov (United States)

Mertie, J.B.

1958-01-01

The principal source of zirconium and hafnium is zircon, though a minor source is baddeleyite, mined only in Brazil. Zircon is an accessory mineral in igneous, metamorphic, and sedimentary rocks, but rarely occurs in hardrock in minable quantities. The principal sources of zircon are therefore alluvial deposits, which are mined in many countries of five continents. The principal commercial deposits in the United States are in Florida, though others exist elsewhere in the southeastern Coastal Plain. The evidence indicates that conditions for the accumulation of workable deposits of heavy minerals were more favorable during the interglacial stages of the Pleistocene epoch than during Recent time. Therefore detrital ores of large volume and high tenor are more likely to be found in the terrace deposits than along the present beaches. Other concentrations of heavy minerals, however, are possible at favored sites close to the Fall Line where the Tuscaloosa formation rests upon the crystalline rocks of the Piedmont province. A score of heavy and semiheavy minerals occur in the detrital deposits of Florida, but the principal salable minerals are ilmenite, leucoxene, rutile, and zircon, though monazite and staurolite are saved at some mining plants. Commercial deposits of heavy minerals are generally required to have a tenor of 4 percent, though ores with a lower tenor can be mined at a profit if the content of monazite is notably high. The percentages of zircon in the concentrates ranges from 10 to 16 percent, and in eastern Florida from 13 to 15 percent. Thus the tenor in zircon of the ore-bearing sands ranges from 0.4 to 0.6 percent. The content of hafnium in zircon is immaterial for many uses, but for some purposes very high or very low tenors in hafnium are required. Alluvial zircon cannot be separated into such varieties, which, if needed, must be obtained from sources in bedrock. It thus becomes necessary to determine the Hf : Zr ratios in zircon from many kinds of

Niobium and hafnium grown on porous membranes

International Nuclear Information System (INIS)

Morant, C.; Marquez, F.; Campo, T.; Sanz, J.M.; Elizalde, E.

2010-01-01

In this work we report on a method for fabricating highly ordered nanostructures of niobium and hafnium metals by physical vapour deposition using two different templates: anodized aluminum oxide membranes (AAO) and zirconium onto AAO membranes (Zr/AAO). The growth mechanism of these metal nanostructures is clearly different depending on the material used as a template. A different morphology was obtained by using AAO or Zr/AAO templates: when the metal is deposited onto AAO membranes, nanospheres with ordered hexagonal regularity are obtained; however, when the metal is deposited onto a Zr/AAO template, highly ordered nanocones are formed. The experimental approach described in this work is simple and suitable for synthesizing nanospheres or nanoholes of niobium and hafnium metals in a highly ordered structure.

Analytical study of zirconium and hafnium α-hydroxy carboxylates

International Nuclear Information System (INIS)

Terra, V.R.

1991-01-01

The analytical study of zirconium and hafnium α-hydroxy carboxylates was described. For this purpose dl-mandelic, dl-p-bromo mandelic, dl-2-naphthyl glycolic, and benzilic acids were prepared. These were used in conjunction with glycolic, dl-lactic, dl-2-hydroxy isovaleric, dl-2-hydroxy hexanoic, and dl-2-hydroxy dodecanoic acids in order to synthesize the zirconium(IV) and hafnium(IV) tetrakis(α-hydroxy carboxylates). The compounds were characterized by melting point determination, infrared spectroscopy, thermogravimetric analysis, calcination to oxides and X-ray diffractometry by the powder method. (C.G.C)

High temperature evaporation of titanium, zirconium and hafnium carbides

International Nuclear Information System (INIS)

Gusev, A.I.; Rempel', A.A.

1991-01-01

Evaporation of cubic nonstoichiometric carbides of titanium, zirconium and hafnium in a comparatively low-temperature interval (1800-2700) with detailed crystallochemical sample certification is studied. Titanium carbide is characterized by the maximum evaporation rate: at T>2300 K it loses 3% of sample mass during an hour and at T>2400 K titanium carbide evaporation becomes extremely rapid. Zirconium and hafnium carbide evaporation rates are several times lower than titanium carbide evaporation rates at similar temperatures. Partial pressures of metals and carbon over the carbides studied are calculated on the base of evaporation rates

Determination of hafnium, molybdenum, and vanadium in niobium and niobium-based alloys by atomic absorption spectrometry

International Nuclear Information System (INIS)

Ide, Kunikazu; Kobayashi, Takeshi; Sudo, Emiko.

1985-01-01

The analytical procedure is as follows: Weigh 1 g of a sample and put it into a 100 cm 3 PTFE beaker. Add 5 ml of distilled water and 5 ml of hydrofluoric acid, and then heat the solution on a hot plate, adding 3 ml of nitric acid dropwise. Dilute the solution to 100 cm 3 with distilled water. When hafnium is determined, add 2 g of diammonium titanium hexafluoride ((NH 4 ) 2 TiF 6 )) before dilution. Working standard solutions are prepared by adding the stock standard solutions of hafnium, molybdenum, and vanadium into niobium solutions. When hafnium is determined, add 2 g of (NH 4 ) 2 TiF 6 and the alloying elements in amounts corresponding to those in sample solutions into the working standard solutions. The tolerable amounts of hydrofluoric acid were 2.9 M, 2.1 M, and 3.1 M and those of nitric acid were 1.0 M, 1.6 M, and 1.6 M for hafnium, molybdenum, and vanadium, respectively. It was found that (NH 4 ) 2 TiF 6 greatly increased the sensitivity for hafnium determination. Niobium showed minus effect for hafnium and plus effect for molybdenum and vanadium. The atomic absorption of molybdenum and vanadium were not influenced by the presence of 20 % of each alloying element, while the atomic absorption of hafnium was given plus effect by 20 % of zirconium, iron, cobalt, nickel, manganese, chromium or vanadium and minus effect by 20 % tungsten. The analytical values of hafnium, molybdenum, and vanadium in niobium-based alloys by this method showed a good agreement with those by X-ray fluorescence analysis. The lower limits of determination (S/N=2) were 0.05, 0.001, and 0.002 % and the relative standard deviation were 3, 1, and 1.5 % for hafnium, molybdenum, and vanadium, respectively. (author)

Separation of zirconium from hafnium by ion exchange

Energy Technology Data Exchange (ETDEWEB)

Felipe, Elaine C.B.; Palhares, Hugo G.; Ladeira, Ana Claudia Q., E-mail: elainecfelipe@yahoo.com.br, E-mail: hugopalhares@gmail.com, E-mail: ana.ladeira@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2013-07-01

Zirconium and hafnium are two of the most important metals for the nuclear industry. Hafnium occurs in all zirconium ores usually in the range 2 - 3%. However, for the most nuclear industry applications, it is necessary to use a zirconium of extremely pure level. The current work consists in the separation of zirconium and hafnium by the ion exchange method in order to obtain a zirconium concentrate of high purity. The zirconium and hafnium liquors were produced from the leaching of the Zr(OH){sub 4} and Hf(OH){sub 4} with nitric acid for 24 hours. From these two liquors it was prepared one solution containing 7.5 x 10{sup -2} mol L{sup -1} of Zr and 5.8 x 10{sup -3} mol L{sup -1} of Hf with acidity of 1 M. Ion exchange experiments were carried out in batch with the resins Dowex 50WX4, Dowex 50WX8 100, Dowex 50WX8 50, Amberlite IR-120 and Marathon C at constant temperature 28 deg C. Other variables such as, acidity and agitation were kept constant. The data were adjusted to Langmuir equation in order to calculate the maximum loading capacity (q{sub max}) of the resins, the distribution coefficient (K{sub d}) for Zr and Hf and the separation factor (α{sub Hf}{sup Zr} ). The results of maximum loading capacity (q{sub max}) for Zr and Hf, in mmol g{sup -}1, showed that the most suitable resins for columns experiments are: Dowex 50WX4 50 (q{sub max} Z{sub r} = 2.21, Hf = 0.18), Dowex 50WX8 50 (q{sub max} Zr = 1.89, Hf = 0.13) and Amberlite (q{sub max} Zr = 1.64, Hf = 0.12). However, separations factors, α{sub Hf}{sup Zr}, showed that the resins are not selective. (author)

On the stabilization of niobium(V) solutions by zirconium(IV) and hafnium(IV)

DEFF Research Database (Denmark)

Sørensen, E.; Bjerre, A.B.

1992-01-01

Niobium cannot be separated from zirconium or hafnium when these elements occur together in solution with common anions such as chloride and sulphate. This is ascribed to the co-polymerization of niobium(V) and the hydrolysed ionic species of zirconium(IV) and hafnium(IV) to form colloidal...

Analysis of hafnium in zirconium alloys

International Nuclear Information System (INIS)

Kondo, Isao; Sakai, Fumiaki; Ohuchi, Yoshifusa; Nakamura, Hisashi

1977-01-01

It is required to analyse alloying components and impurity elements in the acceptance analysis of zirconium alloys as the material for fuel cladding tubes and pressure tubes for advanced thermal reactors. Because of extreme similarity in chemical properties between zirconium and hafnium, about 100 ppm of hafnium is usually contained in zirconium alloys. Zircaloy-2 alloy and 2.5% Nb-zirconium with the addition of hafnium had been prepared as in-house standard samples for rapid analysis. Study was made on fluorescent X-ray analysis and emission spectral analysis to establish the analytical method. By using these in-house standard samples, acceptance analysis was successfully carried out for the fuel cladding tubes for advanced thermal reactors. Sulfuric acid solution was prepared from JAERI-Z 1, 2 and 3, the standard sample for zircaloy-2 prepared by the Analytical Committee on Nuclear Fuel and Reactor Materials, JAERI, and zirconium oxide (Hf 1 ppm/Zr). Standard Hf solution was added to the sulfuric acid solution step by step, to make up a series of the standard oxide samples by the precipitation process. By the use of these standard samples, the development of the analytical method and joint analysis were made by the three-member analytical technique research group including PNC. The analytical precision for the fluorescent X-ray analysis was improved by attaching a metallic yttrium filter to the window of an X-ray tube so as to suppress the effect due to zirconium matrix. The variation factor of the joint analysis was about 10% to show good agreement, and the indication value was determined. (Kobatake, H.)

Knight shift in scandium and its alloys with hafnium and titanium

International Nuclear Information System (INIS)

Chachkhiani, Z.B.; Chechernikov, V.I.; Martynova, L.F.; Nidel'ko, V.I.; Chachkhiani, L.G.; Georgadze, G.S.

1981-01-01

Results of the investigation of NMR on 45 Sc nuclei and magnetic susceptibility of scandium and its solid solutions with titanium and hafnium are presented. It is shown that the existing hybridization of S and d zones in pure scandium and its alloys with titanium and hafnium affects the Knight shift reducing the value of the contact contribution. The temperature behaviour of the Knight shift from the temperature dependence and spin susceptibility of collectivized d electrons [ru

Composition and microstructure of zirconium and hafnium germanates obtained by different chemical routes

International Nuclear Information System (INIS)

Utkin, A.V.; Prokip, V.E.; Baklanova, N.I.

2014-01-01

The phase composition and morphology of zirconium and hafnium germanates synthesized by ceramic and co-precipitation routes were studied. The products were characterized using high-temperature X-ray diffraction analysis (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and thermal (TG/DTA) analysis. To investigate the phase composition and stoichiometry of compounds the unit cell parameters were refined by full-profile Rietveld XRD analysis. The morphology of products and its evolution during high-temperature treatment was examined by SEM analysis. It was stated that there is the strong dependence of the phase composition and morphology of products on the preparation route. The ceramic route requires a multi-stage high-temperature treatment to obtain zirconium and hafnium germanates of 95% purity or more. Also, there are strong diffusion limitations to obtain hafnium germanate Hf 3 GeO 8 by ceramic route. On the contrary, the co-precipitation route leads to the formation of nanocrystalline single phase germanates of stoichiometric composition at a relatively low temperatures (less than 1000 °C). The results of quantitative XRD analysis showed the hafnium germanates are stoichiometric compounds in contrast to zirconium germanates that form a set of solid solutions. This distinction may be related to the difference in the ion radii of Zr and Hf. - Graphical abstract: The phase composition and morphology of zirconium and hafnium germanates synthesized by ceramic and co-precipitation routes were studied. It was stated that there is the strong dependence of the phase composition and morphology of products on the preparation route. Display Omitted - Highlights: • Zr and Hf germanates were synthesized by ceramic and co-precipitation routes. • The morphology of products depends on the synthesis parameters. • Zirconium germanates forms a set of solid solutions. • Hafnium germanates are stoichiometric compounds

Recovery of hafnium radioisotopes from a proton irradiated tantalum target

International Nuclear Information System (INIS)

Taylor, W.A.; Garcia, J.G.; Hamilton, V.T.; Heaton, R.C.; Jamriska, D.J.; Ott, M.A.; Philips, D.R.; Radzinski, S.D.

1998-01-01

The 178m2 Hf nucleus, with its long half-life (31 y) and high-spin isomeric state (16 + ) is desired for new and exotic nuclear physics studies. The Los Alamos Radioisotope Program irradiated a kilogram of natural tantalum at the Los Alamos Meson Physics Facility in early 1981. After fifteen years of decay, this target was ideal for the recovery of 178m2 Hf. There was more than a millicurie of 178m2 Hf produced during this irradiation and there has been a sufficient period of time for most of the other hafnium radioisotopes to decayed away. Traditionally, separation techniques for recovering hafnium isotopes from tantalum targets employ solvent extractions with reagents that are considered hazardous. These techniques are no longer condoned because they generate a mixed-waste (radioactive and hazardous components) that can not be treated for disposal. In this paper we describe a new and unique procedure for the recovery of hafnium radioisotopes from a highly radioactive, proton irradiated, tantalum target using reagents that do not contribute a hazardous waste component. (author)

1 CFR 18.7 - Signature.

Science.gov (United States)

2010-01-01

... 1 General Provisions 1 2010-01-01 2010-01-01 false Signature. 18.7 Section 18.7 General Provisions... PREPARATION AND TRANSMITTAL OF DOCUMENTS GENERALLY § 18.7 Signature. The original and each duplicate original... stamped beneath the signature. Initialed or impressed signatures will not be accepted. Documents submitted...

28 CFR 18.7 - Discovery.

Science.gov (United States)

2010-07-01

... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Discovery. 18.7 Section 18.7 Judicial Administration DEPARTMENT OF JUSTICE OFFICE OF JUSTICE PROGRAMS HEARING AND APPEAL PROCEDURES § 18.7 Discovery.... Such order may be entered upon a showing that the deposition is necessary for discovery purposes, and...

Investigation of colourless complexes of thorium, hafnium and zirconium

International Nuclear Information System (INIS)

Kiciak, S.; Stefanowicz, T.; Gontarz, H.; Swit, Z.

1980-01-01

The investigations conducted in the Institute of General Chemistry of Poznan Technical University in partial cooperation with Kharkhof Technical University related with thorium, hafnium and zirconium complexes are reviewed. (author)

Separation process of zirconium and hafnium; Procede de separation du zirconium et du hafnium

Energy Technology Data Exchange (ETDEWEB)

Hure, J; Saint-James, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1955-07-01

About the separation different processes of zirconium-hafnium, the extraction by solvent in cross-current is the most easily the process usable on an industrial scale. It uses tributyl phosphate as solvent, diluted with white spirit to facilitate the decanting. Some exploratory tests showed that nitric environment seemed the most favorable for extraction; but a lot of other factors intervene in the separation process. We studied the influence of the acidity successively, the NO{sub 3}{sup -} ions concentration, the role of the cation coming with NO{sub 3}{sup -}, as well as the influence of the concentration of zirconium in the solution on the separation coefficient {beta} = {alpha}{sub Zr} / {alpha}{sub Hf}. (M.B.) [French] Des differents procedes de separation zirconium-hafnium, l'extraction par solvant en contre-courant est le procede le plus facilement utilisable a l'echelle industrielle. On utilise comme solvant le phosphate de tributyle, dilue avec du white spirit pour faciliter les decantations. Des essais preliminaires ont montre que le milieu nitrique semblait le plus favorable a l'extraction; mais beaucoup d'autres facteurs interviennent dans le processus de separation. Nous avons etudie successivement l'influence de l'acidite, celle de la concentration en ions NO{sub 3}{sup -}, le role du cation accompagnant NO{sub 3}{sup -}, ainsi que l'influence de la concentration en zirconium de la solution sur le coefficient de separation {beta} = {alpha}{sub Zr} / {alpha}{sub Hf}. (MB)

Strong influence of polymer architecture on the microstructural evolution of hafnium-alkoxide-modified silazanes upon ceramization.

Science.gov (United States)

Papendorf, Benjamin; Nonnenmacher, Katharina; Ionescu, Emanuel; Kleebe, Hans-Joachim; Riedel, Ralf

2011-04-04

The present study focuses on the synthesis and ceramization of novel hafnium-alkoxide-modified silazanes as well as on their microstructure evolution at high temperatures. The synthesis of hafnia-modified polymer-derived SiCN ceramic nanocomposites is performed via chemical modification of a polysilazane and of a cyclotrisilazane, followed by cross-linking and pyrolysis in argon atmosphere. Spectroscopic investigation (i.e., NMR, FTIR, and Raman) shows that the hafnium alkoxide reacts with the N-H groups of the cyclotrisilazane; in the case of polysilazane, reactions of N-H as well as Si-H groups with the alkoxide are observed. Consequently, scanning and transmission electron microscopy studies reveal that the ceramic nanocomposites obtained from cyclotrisilazane and polysilazane exhibited markedly different microstructures, which is a result of the different reaction pathways of the hafnium alkoxide with cyclotrisilazane and with polysilazane. Furthermore, the two prepared ceramic nanocomposites are unexpectedly found to exhibit extremely different high-temperature behavior with respect to decomposition and crystallization; this essential difference is found to be related to the different distribution of hafnium throughout the ceramic network in the two samples. Thus, the homogeneous distribution of hafnium observed in the polysilazane-derived ceramic leads to an enhanced thermal stability with respect to decomposition, whereas the local enrichment of hafnium within the matrix of the cyclotrisilazane-based sample induces a pronounced decomposition upon annealing at high temperatures. The results indicate that the chemistry and architecture of the precursor has a crucial effect on the microstructure of the resulting ceramic material and consequently on its high-temperature behavior. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Separation of hafnium from zirconium in sulfuric acid solutions using pressurized ion exchange

International Nuclear Information System (INIS)

Hurst, F.J.

1981-01-01

High-resolution pressurized ion exchange has been used successfully to study and separate hafnium and zirconium sulfate complexes by chromatographic elution from Dowex 50W-X8 (15 to 25 μm) resin with sulfuric acid solutions. Techniques were developed to continuously monitor the column effluents for zirconium and hafnium by reaction with fluorometric and colorimetric reagents. Since neither reagent was specific for either metal ion, peak patterns were initially identified by using the stable isotopes 90 Zr and 180 Hf as fingerprints of their elution position. Distribution ratios for both zirconium and hafnium decrease as the inverse fourth power of the sulfuric acid concentration below 2N and as the inverse second power at higher acid concentration. The hafnium-to-zirconium separation factor is approximately constant (approx. 8) over the 0.5 to 3N range. Under certain conditions, an unseparated fraction was observed that was not retained by the resin. The amount of this fraction which is thought to be a polymeric hydrolysis product appears to be a function of metal and sulfuric acid concentrations. Conditions are being sought to give the highest zirconium concentration and the lowest acid concentration that can be used as a feed material for commercial scale-up in the continuous annular chromatographic (CAC) unit without formation of the polymer

Separation of zirconium and hafnium from acompanying elements by paper chromatography in the systems of alcohol-acid

International Nuclear Information System (INIS)

Lebedeva, G.G.; Viktorova, M.E.

1980-01-01

Solvents have been chosen and investigated which provide expressed separation of zirconium and hafnium at the analysis of mineral raw materials by paper chromatography. The systems with HNO 3 and HCl containing methyl, ethyl, propyl and butyl alcohols have been studied as mobile phases for separation of zirconium and hafnium. It has been shown that alcohol contents and solvent acidity affect the Rsub(f) value of these elements. The C 2 H 5 OH-5MHCl and C 2 H 5 OH-5MHNO 3 systems are most optimal for pre-concentration of zirconium and hafnium

187Re-187Os systematics in meteorites and cosmo-chemical consequences

International Nuclear Information System (INIS)

Luck, J.-M.; Allegre, C.J.

1983-01-01

Using a recently published technique (Luck et al. Nature; 283:256 (1980)) based on isotope dilution, 187 Re- 187 Os systematics in meteorites have been measured with an improved analytical procedure and a recalibrated osmium spike. Using previous results, corrected for this change in spike calibration, in addition to the present data from analyses of irons and the iron phases of 10 chondrites and of one mesosiderite, a revised and more precise value is proposed for the rhenium decay constant, together with a new estimate for the age of the Galaxy. (U.K.)

Low-voltage bendable pentacene thin-film transistor with stainless steel substrate and polystyrene-coated hafnium silicate dielectric.

Science.gov (United States)

Yun, Dong-Jin; Lee, Seunghyup; Yong, Kijung; Rhee, Shi-Woo

2012-04-01

The hafnium silicate and aluminum oxide high-k dielectrics were deposited on stainless steel substrate using atomic layer deposition process and octadecyltrichlorosilane (OTS) and polystyrene (PS) were treated improve crystallinity of pentacene grown on them. Besides, the effects of the pentacene deposition condition on the morphologies, crystallinities and electrical properties of pentacene were characterized. Therefore, the surface treatment condition on dielectric and pentacene deposition conditions were optimized. The pentacene grown on polystyrene coated high-k dielectric at low deposition rate and temperature (0.2-0.3 Å/s and R.T.) showed the largest grain size (0.8-1.0 μm) and highest crystallinity among pentacenes deposited various deposition conditions, and the pentacene TFT with polystyrene coated high-k dielectric showed excellent device-performance. To decrease threshold voltage of pentacene TFT, the polystyrene-thickness on high-k dielectric was controlled using different concentration of polystyrene solution. As the polystyrene-thickness on hafnium silicate decreases, the dielectric constant of polystyrene/hafnium silicate increases, while the crystallinity of pentacene grown on polystyrene/hafnium silicate did not change. Using low-thickness polystyrene coated hafnium silicate dielectric, the high-performance and low voltage operating (pentacene thin film transistor (μ: ~2 cm(2)/(V s), on/off ratio, >1 × 10(4)) and complementary inverter (DC gains, ~20) could be fabricated.

Primary hafnium metal sponge and other forms, approved standard 1973

International Nuclear Information System (INIS)

Anon.

1975-01-01

A specification is presented covering virgin hafnium metal commonly designated as sponge because of its porous, sponge-like texture; it may also be in other forms such as chunklets. The specification does not cover crystal bar

Dicty_cDB: VFB187 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available VF (Link to library) VFB187 (Link to dictyBase) - - - - VFB187P (Link to Original s...ite) VFB187F 556 VFB187Z 289 VFB187P 845 - - Show VFB187 Library VF (Link to library) Clone ID VFB187 (Link to dict...yBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig - Original site URL http://dictycdb.biol.ts...25 Homology vs DNA Score E Sequences producing significant alignments: (bits) Val...alar cDNA clone LRR7-f02 5' similar to Calreticulin, mRNA sequence. 56 8e-04 1 CB937139 |CB937139.1 IpCGJx13_12_E07_23 IpCGJx13 Ict

Evolution of the hafnium isotopic composition in the RBMK reactor

International Nuclear Information System (INIS)

Jurkevicius, A.; Remeikis, V.

2002-01-01

The isotopic composition of hafnium in the radial neutron flux sensor of the RBMK-1500 reactor, the rates of the neutron absorption on Hf isotopes and the neutron spectrum in the sensor were numerically modeled. The sequence SAS2 (Shielding Analysis Sequence) program from the package SCALE 4.4A and the HELIOS code system were used for calculations. It has been obtained that the overall neutron absorption rates in hafnium for the sensors located in the 2.4 % and 2.6 % enrichment uranium-erbium nuclear fuel assemblies are by 16 % and 19 % lower than in the 2.0 % enrichment uranium nuclear fuel assemblies. The overall neutron absorption rate in hafnium decreases 2.70-2.75 times due to the sensor burnup to 5800 MW d. The sensitivity of the Hf sensors to the thermal neutron flux increases twice due to the nuclear fuel assembly burnup to 3000 MW d. The corrective factors ξ d (I) at the different integral current I of the sensors and ξ td (E) at the different burnup E of the nuclear fuel assemblies were calculated. The obtained dependence ξ d (I) calculated numerically was compared to the experimental one determined by comparing signals of the fresh sensor and the sensor with the integral current I and by processing repeated calibration results of Hf sensors in RBMK-1500 reactors. The relative relationship coefficients K T (T FA ) were found for all RBMK-1500 nuclear fuel types. (author)

Preparation of hafnium metal by calciothermic reduction of HfO2

International Nuclear Information System (INIS)

Sharma, I.G.; Vijay, P.L.; Sehra, J.C.; Sundaram, C.V.

1975-01-01

Hafnium metal powder has been produced by the calciothermic reduction of hafnium oxide. The influence of various experimental parameters - such as amount of calcium in excess of stoichiometric requirement, temperature, and time of reduction - on the yield and purity of the metal has been studied. The metal powder obtained by reduction at 960 0 C (two hours) with a calcium excess of 70% analysed 600 ppm of oxygen and 147 ppm of nitrogen. A reduction efficiency of 96% has been achieved under these conditions. The refining of the powder by electron beam melting, fused salt electrolysis, and iodide process has been studied. The oxygen content in the metal could be brought down from 6900 to 148 ppm by electron beam melt-refining. (author)

ENTIRELY AQUEOUS SOLUTION-GEL ROUTE FOR THE PREPARATION OF ZIRCONIUM CARBIDE, HAFNIUM CARBIDE AND THEIR TERNARY CARBIDE POWDERS

Directory of Open Access Journals (Sweden)

Zhang Changrui

2016-07-01

Full Text Available An entirely aqueous solution-gel route has been developed for the synthesis of zirconium carbide, hafnium carbide and their ternary carbide powders. Zirconium oxychloride (ZrOCl₂.8H₂O, malic acid (MA and ethylene glycol (EG were dissolved in water to form the aqueous zirconium carbide precursor. Afterwards, this aqueous precursor was gelled and transformed into zirconium carbide at a relatively low temperature (1200 °C for achieving an intimate mixing of the intermediate products. Hafnium and the ternary carbide powders were also synthesized via the same aqueous route. All the zirconium, hafnium and ternary carbide powders exhibited a particle size of ∼100 nm.

On the phase formation of sputtered hafnium oxide and oxynitride films

International Nuclear Information System (INIS)

Sarakinos, K.; Music, D.; Mraz, S.; Baben, M. to; Jiang, K.; Nahif, F.; Braun, A.; Zilkens, C.; Schneider, J. M.; Konstantinidis, S.; Renaux, F.; Cossement, D.; Munnik, F.

2010-01-01

Hafnium oxynitride films are deposited from a Hf target employing direct current magnetron sputtering in an Ar-O 2 -N 2 atmosphere. It is shown that the presence of N 2 allows for the stabilization of the transition zone between the metallic and the compound sputtering mode enabling deposition of films at well defined conditions of target coverage by varying the O 2 partial pressure. Plasma analysis reveals that this experimental strategy facilitates control over the flux of the O - ions which are generated on the oxidized target surface and accelerated by the negative target potential toward the growing film. An arrangement that enables film growth without O - ion bombardment is also implemented. Moreover, stabilization of the transition sputtering zone and control of the O - ion flux without N 2 addition is achieved employing high power pulsed magnetron sputtering. Structural characterization of the deposited films unambiguously proves that the phase formation of hafnium oxide and hafnium oxynitride films with the crystal structure of HfO 2 is independent from the O - bombardment conditions. Experimental and theoretical data indicate that the presence of vacancies and/or the substitution of O by N atoms in the nonmetal sublattice favor the formation of the cubic and/or the tetragonal HfO 2 crystal structure at the expense of the monoclinic HfO 2 one.

Solvent extraction of titanium(IV), zirconium(IV) and hafnium(IV) salicylates using liquid ion exchangers

Energy Technology Data Exchange (ETDEWEB)

Sundaramurthi, N M; Shinde, V M

1989-02-01

A solvent extraction method is proposed for the extraction of quadrivalent titanium, zirconium an hafnium from salicylate media using liquid ion exchangers such as Aliquat 336 and trioctylamine dissolved in xylene. The optimum conditions were evaluated from a critical study of the following: pH, salicylate concentration, amine concentration, diluent and period of equilibration. The method allows the separation of titanium, zirconium and hafnium from binary mixtures containing commonly associated metal ions and is applicable to the analysis of real samples such as BCS-CRM 387 nimonic 901, BCS-CRM 243/4 ferro-titanium, BCS-CRM 307 magnesium alloy and BCS-CRM 388 zircon. Titanium is determined either with hydrogen peroxide or by atomic absorption spectrometry whereas zirconium and hafnium are determined spectrophotometrically with Alizarin Red S and Zylenol Orange, respectively. The results of both separation and analysis are reported. The method is precise, accurate and fast.

Solvent extraction of zirconium and hafnium using MIBK-HSCN-HCL process

International Nuclear Information System (INIS)

Borges, J.A.L.; Cunha, O.G.C. da

1985-01-01

The separation process of zirconium and hafnium, using MIBK as extractant in a set of mixer-settler is described. The chemical analysis was done by X-ray fluorescence and emission spectrography. (Author) [pt

Radiation effects on the electrical properties of hafnium oxide based MOS capacitors.

Energy Technology Data Exchange (ETDEWEB)

Petrosky, J. C. (Air Force Institute of Technology, Wright-Patterson Air Force Base, OH); McClory, J. W. (Air Force Institute of Technology, Wright-Patterson Air Force Base, OH); Bielejec, Edward Salvador; Foster, J. C. (Air Force Institute of Technology, Wright-Patterson Air Force Base, OH)

2010-10-01

Hafnium oxide-based MOS capacitors were investigated to determine electrical property response to radiation environments. In situ capacitance versus voltage measurements were analyzed to identify voltage shifting as a result of changes to trapped charge with increasing dose of gamma, neutron, and ion radiation. In situ measurements required investigation and optimization of capacitor fabrication to include dicing, cleaning, metalization, packaging, and wire bonding. A top metal contact of 200 angstroms of titanium followed by 2800 angstroms of gold allowed for repeatable wire bonding and proper electrical response. Gamma and ion irradiations of atomic layer deposited hafnium oxide on silicon devices both resulted in a midgap voltage shift of no more than 0.2 V toward less positive voltages. This shift indicates recombination of radiation induced positive charge with negative trapped charge in the bulk oxide. Silicon ion irradiation caused interface effects in addition to oxide trap effects that resulted in a flatband voltage shift of approximately 0.6 V also toward less positive voltages. Additionally, no bias dependent voltage shifts with gamma irradiation and strong oxide capacitance room temperature annealing after ion irradiation was observed. These characteristics, in addition to the small voltage shifts observed, demonstrate the radiation hardness of hafnium oxide and its applicability for use in space systems.

Investigation of chlorination of zirconium and hafnium and their compounds in discharge from hollow cathode

International Nuclear Information System (INIS)

Ioffe, R.B.; Korovin, Yu.I.

1978-01-01

The possibility is investigated of chlorinating various zirconium and hafnium compounds (metal, oxide, carbide) in a hot discharge from a hollow cathode with various chlorinating reagents: copper monochloride, nickel chloride, magnesium chloride, for the purpose of accelerating their entrance into the excitation zone. It has been shown thermodynamically and experimentally that chlorination of metal zirconium and hafnium and their carbides with copper monochloride in hot hollow cathode conditions provides a sharp increase in the intensity of the lines of these elements

Development and characterization of ultrathin hafnium titanates as high permittivity gate insulators

Science.gov (United States)

Li, Min

High permittivity or high-kappa materials are being developed for use as gate insulators for future ultrascaled metal oxide semiconductor field effect transistors (MOSFETs). Hafnium containing compounds are the leading candidates. Due to its moderate permittivity, however, it is difficult to achieve HfO2 gate structures with an EOT well below 1.0 nm. One approach to increase HfO2 permittivity is combining it with a very high-kappa material, such as TiO2. In this thesis, we systematically studied the electrical and physical characteristics of high-kappa hafnium titanates films as gate insulators. A series of HfxTi1-xO2 films with well-controlled composition were deposited using an MOCVD system. The physical properties of the films were analyzed using a variety of characterization techniques. X-ray micro diffraction indicates that the Ti-rich thin film is more immune to crystallization. TEM analysis showed that the thick stoichiometric HfTiO 4 film has an orthorhombic structure and large anisotropic grains. The C-V curves from the devices with the hafnium titanates films displayed relatively low hysteresis. In a certain composition range, the interfacial layer (IL) EOT and permittivity of HfxTi1-x O2 increases linearly with increasing Ti. The charge is negative for HfxTi1-xO2/IL and positive for Si/IL interface, and the magnitude increases as Hf increases. For ultra-thin films (less than 2 nm EOT), the leakage current increases with increasing HE Moreover, the Hf-rich sample has weaker temperature dependence of the current. In the MOSFET devices with the hafnium titanates films, normal transistor characteristics were observed, also electron mobility degradation. Next, we investigated the effects that different pre-deposition surface treatments, including HF dipping, NH3 surface nitridation, and HfO2 deposition, have on the electrical properties of hafnium titanates. Surface nitridation shows stronger effect than the thin HfO2 layer. The nitrided samples displayed a

Separation of zirconium and hafnium using paper distribution chromatography

International Nuclear Information System (INIS)

Lebedeva, G.G.; Viktorova, M.E.

1981-01-01

A method is suggested of chromatographic separation of zirconium and hafnium in a CCl 4 -tributyl phosphate system (1:9) containing KCl as a salting-out agent in 5 M HNO 3 at 28-30 deg C. Zr and Hf are deterfmined in articiial mixtures under optimal chromatography conditions using visual colorimetry [ru

21 CFR 146.187 - Canned prune juice.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Canned prune juice. 146.187 Section 146.187 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Beverages § 146.187 Canned prune juice. (a) Canned prune juice is the food prepared from a water extract of...

Hafnium as a prospective absorber for VVER-1000 reactors of Ukraine

International Nuclear Information System (INIS)

Afanas'ev, A.A.; Konotop, Yu.F.; Odejchuk, N.L.

2000-01-01

Nuclear-physical parameters of hafnium having in mind its use as an absorber, are considered. Technical aspects of Hf production are exposed. Use of B 4 C/Hf absorber is twice cheaper than a standard one

/sup 187/Re-/sup 187/Os systematics in meteorites and cosmo-chemical consequences

Energy Technology Data Exchange (ETDEWEB)

Luck, J M; Allegre, C J [Paris-6 Univ., 75 (France). Inst. de Physique du Globe

1983-03-10

Using a recently published technique (Luck et al. Nature; 283:256 (1980)) based on isotope dilution, /sup 187/Re-/sup 187/Os systematics in meteorites have been measured with an improved analytical procedure and a recalibrated osmium spike. Using previous results, corrected for this change in spike calibration, in addition to the present data from analyses of irons and the iron phases of 10 chondrites and of one mesosiderite, a revised and more precise value is proposed for the rhenium decay constant, together with a new estimate for the age of the Galaxy.

Evaluation of thermodynamic data on zirconium and hafnium halides and oxyhalides by means of transport experiments

International Nuclear Information System (INIS)

Dittmer, G.; Niemann, U.

1987-01-01

A consistent set of thermodynamic data for zirconium and hafnium halides, oxides and oxyhalides was achieved. It was found that formation enthalpies of gaseous compounds could be derived from solubility measurements together with theoretical estimations and a revision of literature data. Free energy functions were calculated employing statistical mechanics. Data for liquid and solid compounds were obtained via sublimation and vaporization data. Chemical equilibria of zirconium and hafnium with halogens are discussed. 51 refs.; 16 figs.; 14 tabs

Electrodeposition in molten salts of metals used in nuclear industry: hafnium and uranium

International Nuclear Information System (INIS)

Serrano, K.

1998-01-01

The aim of this work is to study the electrodeposition in molten salts of metals used in nuclear industry: hafnium and uranium. The experiment is carried out in a molten alkaline halogenide medium in a temperature range between 670 and 750 degrees Celsius. The first part of this work concerns more particularly the electrochemical behaviour of the hafnium and uranium ions in the electrolytic solution. The reduction mechanisms of these ions have been studied by the use of three methods: cyclic voltametry, chrono-potentiometry and square wave voltametry. Results have shown that the process of metal deposition is difficult to explain because secondary reactions (as for instance: adsorption phenomena or cathodic deposit dissolution) occur. The uranium germination has then been studied by modelling of chrono-amperograms. The experiments have shown that the deposition is the result of the initial uranium crystal growth and depends on the electrolyte diffusion. The second part of this work deals with the implementation of hafnium and uranium deposition taking into account the preceding mechanistic studies. Depositions have all been observed by physical methods as for instance scanning electron microscopy. Particular experimental solutions (soluble anode, addition of fluoride ions to the electrolyte) have been used. The obtained deposition of hafnium is smooth and adheres very well to the substrate. The uranium depositions have been implemented with the use of a soluble anode. Uranium is deposited in a dendritic shape to the cathode. It has also been shown that the electro-kinetic parameters (temperature, uranium ions concentration, current density) have not an important influence on the dendritic morphology of the deposition. This morphology could be the consequence of particular convection movements to the surface of the cathode. (O.M.)

Synthesis and characterization of Ho3+ doped hafnium oxide TLD for radiation dosimeter

International Nuclear Information System (INIS)

Sekar, Nandakumar; Ganesan, Bharanidharan; Sahib, Hajee Reyaz Ali; Aruna, Prakasarao; Ganesan, Singaravelu; Thamilkumar, P.; Rai, R.R.

2017-01-01

Cancer is a dreaded disease which is treated by Radiotherapy, Chemotherapy and Surgery. Radiotherapy plays a vital role in treatment of cancer and recently measurements of invivo radiation dosimetric in patient is of great interest due to high dose gradients in advanced technology like IMRT, IGRT etc. Hence, for the last few decades, a great degree of interest has been shown for the hafnium oxide for radiation dosimetric applications, due to its high dielectric constant, wide band gap and better interface properties such as chemical stability, conduction band offset and thermodynamic stability. In the present study, Synthesis and characterization of Ho 3+ doped Hafnium oxide were carried out and its applications towards radiation dosimeter were investigated

Use of hafnium in control bars of nuclear reactors; Uso de hafnio en barras de control de reactores nucleares

Energy Technology Data Exchange (ETDEWEB)

Ramirez S, J.R.; Alonso V, G. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)]. e-mail: jrrs@nuclear.inin-mx

2003-07-01

Recently the use of hafnium as neutron absorber material in nuclear reactors has been reason of investigation by virtue of that this material has nuclear properties as to the neutrons absorption and structural that can prolong the useful life of the control mechanisms of the nuclear reactors. In this work some of those more significant hafnium properties are presented like nuclear material. Also there are presented calculations carried out with the HELIOS code for fuel cells of uranium oxide and of uranium and plutonium mixed oxides under controlled conditions with conventional bars of boron carbide and also with similar bars to which are substituted the absorbent material by metallic hafnium, the results are presented in this work. (Author)

Plasma spraying of zirconium carbide – hafnium carbide – tungsten cermets

Czech Academy of Sciences Publication Activity Database

Brožek, Vlastimil; Ctibor, Pavel; Cheong, D.-I.; Yang, S.-H.

2009-01-01

Roč. 9, č. 1 (2009), s. 49-64 ISSN 1335-8987 Institutional research plan: CEZ:AV0Z20430508 Keywords : Plasma spraying * cermet coatings * microhardness * zirconium carbide * hafnium carbide * tungsten * water stabilized plasma Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

Study of the radioactive disintegration of /sup 187/Au existence of E0 transitions in /sup 187/Pt?

CERN Document Server

Braham, A B; Bourgeois, C; Desthuilliers-Porquet, M G; Höglund, A; Huck, A; Kilcher, P; Knipper, A; Letessier, J; Serre, Claude; Schuck, C

1979-01-01

The decay /sup 187/Au to /sup 187/Pt has been studied using on-line mass-separated sources produced at ISOCELE (ORSAY) and ISOLDE (CERN). Lifetime measurements are performed with a Gerholm spectrometer and precise conversion electron determination with a 180 degrees spectrograph. A decay scheme is proposed. Low-lying low-spin states in /sup 187/Pt are discussed. Special attention is given to four highly converted transitions (260.3, 262.5, 498.2 and 498.8 keV) which are tentatively considered to have large E0 components. (41 refs).

The study of molybdenites through the 187Re-187Os chronometer

International Nuclear Information System (INIS)

Luck, J.M.; Allegre, C.J.

1982-01-01

We determined the Re and Os concentrations in 11 molybdenites of various ages (30-2700 m.y.) and from various areas. No 'common' osmium has been detected and Os was found to be purely radiogenic. Therefore, by comparing the concentrations, we were able to determine 187 Re- 187 Os ages. For most samples these ages are in good agreement with those measured in surrounding rocks and probably correspond to the age of mineralization. However, two or three Re-Os ages seem unreliable being probably related to some rhenium leaching through later metamorphic and/or hydrothermal events: this shows that the petrographic characteristics of ores and the type of crystallization of MoS 2 are important in choosing samples suitable for dating. Re and Os determinations combined with careful petrographic investigations may give important clues on the genesis and evolution of molybdenum ores. (orig.)

Comparative 187Re-187Os systematics of chondrites: Implications regarding early solar system processes

Science.gov (United States)

Walker, R.J.; Horan, M.F.; Morgan, J.W.; Becker, H.; Grossman, J.N.; Rubin, A.E.

2002-01-01

A suite of 47 carbonaceous, enstatite, and ordinary chondrites are examined for Re-Os isotopic systematics. There are significant differences in the 187Re/188Os and 187Os/188Os ratios of carbonaceous chondrites compared with ordinary and enstatite chondrites. The average 187Re/188Os for carbonaceous chondrites is 0.392 ?? 0.015 (excluding the CK chondrite, Karoonda), compared with 0.422 ?? 0.025 and 0.421 ?? 0.013 for ordinary and enstatite chondrites (1?? standard deviations). These ratios, recast into elemental Re/Os ratios, are as follows: 0.0814 ?? 0.0031, 0.0876 ?? 0.0052 and 0.0874 ?? 0.0027 respectively. Correspondingly, the 187Os/188Os ratios of carbonaceous chondrites average 0.1262 ?? 0.0006 (excluding Karoonda), and ordinary and enstatite chondrites average 0.1283 ?? 0.0017 and 0.1281 ?? 0.0004, respectively (1?? standard deviations). The new results indicate that the Re/Os ratios of meteorites within each group are, in general, quite uniform. The minimal overlap between the isotopic compositions of ordinary and enstatite chondrites vs. carbonaceous chondrites indicates long-term differences in Re/Os for these materials, most likely reflecting chemical fractionation early in solar system history. A majority of the chondrites do not plot within analytical uncertainties of a 4.56-Ga reference isochron. Most of the deviations from the isochron are consistent with minor, relatively recent redistribution of Re and/or Os on a scale of millimeters to centimeters. Some instances of the redistribution may be attributed to terrestrial weathering; others are most likely the result of aqueous alteration or shock events on the parent body within the past 2 Ga. The 187Os/188Os ratio of Earth's primitive upper mantle has been estimated to be 0.1296 ?? 8. If this composition was set via addition of a late veneer of planetesimals after core formation, the composition suggests the veneer was dominated by materials that had Re/Os ratios most similar to ordinary and

Extraction of zirconium and hafnium thiocyanates by CH3COCH2CH.(CH3)2-HSCN solvent from chloride medium

International Nuclear Information System (INIS)

Okada, A.T.

1982-01-01

A zirconium-hafnium separation process for application in nuclear industry is presented. The extraction of zirconium and hafnium thiocyanates in chloride medium by hexone-HSCN solvent was studied. The extraction process was developed, varying the parameters, such as, concentrations of the metals, the thiocyanate ion, the sulphate ion and free acidity in aqueous phase. (Author) [pt

Separation process of zirconium and hafnium

International Nuclear Information System (INIS)

Hure, J.; Saint-James, R.

1955-01-01

About the separation different processes of zirconium-hafnium, the extraction by solvent in cross-current is the most easily the process usable on an industrial scale. It uses tributyl phosphate as solvent, diluted with white spirit to facilitate the decanting. Some exploratory tests showed that nitric environment seemed the most favorable for extraction; but a lot of other factors intervene in the separation process. We studied the influence of the acidity successively, the NO 3 - ions concentration, the role of the cation coming with NO 3 - , as well as the influence of the concentration of zirconium in the solution on the separation coefficient β = α Zr / α Hf . (M.B.) [fr

Synthesis and characterization of hafnium oxide films for thermo and photoluminescence applications

International Nuclear Information System (INIS)

Guzman Mendoza, J.; Aguilar Frutis, M.A.; Flores, G. Alarcon; Garcia Hipolito, M.; Maciel Cerda, A.; Azorin Nieto, J.; Rivera Montalvo, T.; Falcony, C.

2010-01-01

Hafnium oxide (HfO 2 ) films were deposited by the ultrasonic spray pyrolysis process. The films were synthesized from hafnium chloride as raw material in deionized water as solvent and were deposited on corning glass substrates at temperatures from 300 to 600 deg. C. For substrate temperatures lower than 400 deg. C the deposited films were amorphous, while for substrate temperatures higher than 450 deg. C, the monoclinic phase of HfO 2 appeared. Scanning electron microscopy showed that the film's surface resulted rough with semi-spherical promontories. The films showed a chemical composition close to HfO 2 , with an Hf/O ratio of about 0.5. UV radiation was used in order to achieve the thermoluminescent characterization of the films; the 240 nm wavelength induced the best response. In addition, preliminary photoluminescence spectra, as a function of the deposition temperatures, are shown.

A study of a production process for hafnium-free zirconium from zircon

International Nuclear Information System (INIS)

Ratanalert, N.

1985-01-01

The purpose of this experiment was to extract and purify the zirconium from zircon. The effects of time of extraction and stripping of zirconium, concentration of feed solution, concentration of hydrochloric acid in stripping process, equilibrium curve of extraction of zirconium and hafnium and equilibrium curve of stripping zirconium or scrubbing hafnium were studied from standard zirconium and hafnium. The results, subsequently were applied to the extraction procedures for zirconium from zircon. Minus 100 mesh zircon was fused with sodium hydroxide in the ratio of 1 : 6 at 700 degree C for l hour. After fusion the zirconate was leached with water and dissolved in hot concentrated hydrochloric acid. Zirconyl chloride octahydrate crystallized out when the solution was cooled. An agueons solution of zirconyl chloride was used as the feed to the hexone - thiocyanate solvent extraction process. This was prepared by dissolving zirconyl chloride octahydrate crystal in waster. This zirconium feed solution in 1 M HCl and 1 M N H 4 CNS was extracted with 2.7 m N H 4 CNS in hexone and then stripped with 3.6 M HCl the aqueous phase was got rid of thiocyanate ion by extracting with pure hexone, then the zirconium in aqueous phase was precipitated with sulfuric acid and ammonium hydroxide at pH 1.8 - 2.0 and zirconium oxide was obtained by ignition at 700 degree C. The process could be modified to improve the purity of zirconium by using cation exchange resin to get rid of thiocyanate ion after solvent extraction process

Vapor pressure, heat capacities, and phase transitions of tetrakis(tert-butoxy)hafnium

Czech Academy of Sciences Publication Activity Database

Fulem, Michal; Růžička, K.

2011-01-01

Roč. 311, Dec. (2011), s. 25-29 ISSN 0378-3812 Institutional research plan: CEZ:AV0Z10100521 Keywords : tetrakis(tert-butoxy)hafnium * MO precursor * vapor pressure * heat capacity * vaporization enthalpy * enthalpy of fusion Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.139, year: 2011

Pentamethylcyclopentadienyl Zirconium and Hafnium Polyhydride Complexes : Synthesis, Structure, and Reactivity

NARCIS (Netherlands)

Visser, Cindy; Hende, Johannes R. van den; Meetsma, Auke; Hessen, Bart; Teuben, Jan H.

2001-01-01

The half-sandwich zirconium and hafnium N,N-dimethylaminopropyl complexes Cp*M[(CH2)3NMe2]Cl2 (Cp* = η5-C5Me5, M = Zr, 1; Hf, 2) and Cp*M[(CH2)3NMe2]2Cl (M = Zr, 3; Hf, 4) were synthesized by mono- or dialkylation of Cp*MCl3 with the corresponding alkyllithium and Grignard reagents. Hydrogenolysis

Properties of neutron-rich hafnium high-spin isomers

CERN Multimedia

Tungate, G; Walker, P M; Neyens, G; Billowes, J; Flanagan, K; Koester, U H; Litvinov, Y

It is proposed to study highly-excited multi-quasiparticle isomers in neutron-rich hafnium (Z=72) isotopes. Long half-lives have already been measured for such isomers in the storage ring at GSI, ensuring their accessibility with ISOL production. The present proposal focuses on:\\\\ (i) an on-line experiment to measure isomer properties in $^{183}$Hf and $^{184}$Hf, and\\\\ (ii) an off-line molecular breakup test using REXTRAP, to provide Hf$^{+}$ beams for future laser spectroscopy and greater sensitivity for the future study of more neutron-rich isotopes.

Comment: 187 [Taxonomy Icon

Lifescience Database Archive (English)

Full Text Available Common mormon Papilio polytes Papilio_polytes_L.png 187.png Takeru Nakazato (Database Center for Life Scienc...ru Nakazato (Database Center for Life Science) bando 2010/01/12 14:04:54 2010/01/14 19:55:05 ...

Ion-bombardment-induced reduction in vacancies and its enhanced effect on conductivity and reflectivity in hafnium nitride films

Energy Technology Data Exchange (ETDEWEB)

Gu, Zhiqing; Wang, Jiafu; Hu, Chaoquan; Zhang, Xiaobo; Dang, Jianchen; Gao, Jing; Zheng, Weitao [Jilin University, School of Materials Science and Engineering, Key Laboratory of Mobile Materials, MOE, and State Key Laboratory of Superhard Materials, Changchun (China); Zhang, Sam [Nanyang Technological University, School of Mechanical and Aerospace Engineering, Singapore (Singapore); Wang, Xiaoyi [Chinese Academy of Sciences, Key Laboratory of Optical System Advanced Manufacturing Technology, Changchun Institute of Optics, Fine Mechanics and Physics, Changchun (China); Chen, Hong [Jilin University, Department of Control Science and Engineering, Changchun (China)

2016-08-15

Although the role of ion bombardment on electrical conductivity and optical reflectivity of transition metal nitrides films was reported previously, the results were controversial and the mechanism was not yet well explored. Here, we show that proper ion bombardment, induced by applying the negative bias voltage (V{sub b}), significantly improves the electrical conductivity and optical reflectivity in rocksalt hafnium nitride films regardless of level of stoichiometry (i.e., in both near-stoichiometric HfN{sub 1.04} and over-stoichiometric HfN{sub 1.17} films). The observed improvement arises from the increase in the concentration of free electrons and the relaxation time as a result of reduction in nitrogen and hafnium vacancies in the films. Furthermore, HfN{sub 1.17} films have always much lower electrical conductivity and infrared reflectance than HfN{sub 1.04} films for a given V{sub b}, owing to more hafnium vacancies because of larger composition deviation from HfN exact stoichiometry (N:Hf = 1:1). These new insights are supported by good agreement between experimental results and theoretical calculations. (orig.)

Gamma-activation analyses of 187 Os in molybdenite

International Nuclear Information System (INIS)

Dikij, N.P.; Dovbnya, A.N.; Borovlev, V.I.; Lyashko, Yu.V.; Medvedeva, E.P.; Uvarov, V.L.; Val'ter, A.A.; Storizhko, V.E.

1999-01-01

197 Os and 187 Re are used in cosmological studies. Common registration of gamma and X-ray irradiation in compositions containing these radioisotopes permits to increase the accuracy in determination of their content. The results of 187 Os gamma-activation analysis in molybdenite are presented

Results for heterogeneous poisoning of the critical HTR-test facility KAHTER using absorber elements containing hafnium and boron

International Nuclear Information System (INIS)

Drueke, V.; Filges, D.; Nabi, R.; Neef, R.D.; Paul, N.; Schaal, H.

1979-10-01

Experiments and checking computations for investigating the initial-core poisoning of the pebble bed high temperature reactor are described. Following the example of the THTR-300, THTR absorber elements poisoned with hafnium/boron were added to the THTR fuel- and graphite elements of the KAHTER core. Three different hafnium-boron poisoned core loadings, corresponding to 2.7, 5.3 and 8% reactivity compensation, were used in the experiments. For purposes of comparison, two cores exclusively boron poisoned were also studied. The poisoning of these cores correspond to 2.7 and 8% reactivity compensation. The experiments and checking computations should serve to test the accuracy of the theoretical models and data sets in modeling the reactivity effects of absorber poisoned elements in the THTR. In particular, the applicability of the nuclear data of hafnium and the treatment of resonance calculations should be verified. In addition, to determining critical masses and ksub(eff), special emphasis was placed in the experiments on the exact determination of all reactivity effects. In some cases, repeated loading of a configuration also provided a measure of the reproducibility of ksub(eff). The experiments were checked computationally using the GAMTEREX code package and the program system RSYST. These two computation packages contain different data bases, - although the hafnium data are identical -, and the computing models differ in certain phases of the calculations. Both code systems compute ksub(eff) values to within the present accuracy requirements, whereas the program system RSYST gives better agreement with experimental measurements. (orig.) 891 RW/orig. 892 RDG [de

Thermal behaviour of hafnium diethylenetriaminepentaacetate studied using the perturbed angular correlation technique

Energy Technology Data Exchange (ETDEWEB)

Chain, Cecilia Y. [Universidad Nacional de La Plata (Argentina). Dept. de Fisica; Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), La Plata (Argentina). IFLP-CCT; Consejo Nacional de Investigaciones Cientificas y Tecnicas, Buenos Aires (Argentina); Rivas, Patricia [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), La Plata (Argentina). IFLP-CCT; Consejo Nacional de Investigaciones Cientificas y Tecnicas, Buenos Aires (Argentina); Universidad Nacional de La Plata (Argentina). Facultad de Ciencias Agrarias y Forestales; Pasquevich, Alberto F. [Universidad Nacional de La Plata (Argentina). Dept. de Fisica; Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), La Plata (Argentina). IFLP-CCT; Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (CIC-PBA) (Argentina)

2014-07-01

Polyaminecarboxilic ligands like diethylenetriaminepentaacetic acid form stable complexes with many heavy metal ions, excelling as cation chelants especially in the field of radiopharmacy. The aim of this work is to characterize, by using the Time Differential Perturbed Angular Correlations (TDPAC) technique, the hyperfine interactions at hafnium sites in hafnium diethylenetriaminepentaacetate and to investigate their evolution as temperature increases. TDPAC results for KHfDTPA.3H{sub 2}O obtained by chemical synthesis yield a well defined and highly asymmetric interaction of quadrupole frequency ω{sub Q} = 141 Mrad/s, which is consistent with the existence of a unique site for the metal in the crystal lattice. The thermal behaviour of the chelate is investigated by means of differential scanning calorimetry and thermogravimetrical analyses revealing that an endothermic dehydration of KHfDTPA.3H{sub 2}O takes place in one step between 80 C and 180 C. The anhydrous KHfDTPA thus arising is characterized by a fully asymmetric and well defined interaction of quadrupole frequency ω{sub Q} = 168 Mrad/s. (orig.)

Thermal behaviour of hafnium diethylenetriaminepentaacetate studied using the perturbed angular correlation technique

International Nuclear Information System (INIS)

Chain, Cecilia Y.; Rivas, Patricia

2014-01-01

Polyaminecarboxilic ligands like diethylenetriaminepentaacetic acid form stable complexes with many heavy metal ions, excelling as cation chelants especially in the field of radiopharmacy. The aim of this work is to characterize, by using the Time Differential Perturbed Angular Correlations (TDPAC) technique, the hyperfine interactions at hafnium sites in hafnium diethylenetriaminepentaacetate and to investigate their evolution as temperature increases. TDPAC results for KHfDTPA.3H 2 O obtained by chemical synthesis yield a well defined and highly asymmetric interaction of quadrupole frequency ω Q = 141 Mrad/s, which is consistent with the existence of a unique site for the metal in the crystal lattice. The thermal behaviour of the chelate is investigated by means of differential scanning calorimetry and thermogravimetrical analyses revealing that an endothermic dehydration of KHfDTPA.3H 2 O takes place in one step between 80 C and 180 C. The anhydrous KHfDTPA thus arising is characterized by a fully asymmetric and well defined interaction of quadrupole frequency ω Q = 168 Mrad/s. (orig.)

Studies on Optical and Electrical Properties of Hafnium Oxide Nanoparticles

Science.gov (United States)

Jayaraman, Venkatachalam; Sagadevan, Suresh; Sudhakar, Rajesh

2017-07-01

In this paper, the synthesis and physico-chemical properties of hafnium oxide nanoparticles (HfO2 NPs) are analyzed and reported. The synthesis was carried out by the precipitation route by using hafnium tetrachloride (HfCl4) as precursor material with potassium hydroxide (KOH) dissolved in Millipore water. In the precipitation technique, the chemical reaction is comparatively simple, low-cost and non-toxic compared to other synthetic methods. The synthesized HfO2 NPs were characterized by using powder x-ray diffraction (PXRD), ultraviolet-visible (UV-Vis) spectroscopy, Raman analysis, and high-resolution transmission electron microscopy (HRTEM). The monoclinic structure of the HfO2 NPs was resolved utilizing x-ray diffraction (XRD). The optical properties were studied from the UV-Vis absorption spectrum. The optical band gap of the HfO2NPs was observed to be 5.1 eV. The Raman spectrum shows the presence of HfO2 NPs. The HRTEM image showed that the HfO2 NPs were of spherical shape with an average particle size of around 28 nm. The energy-dispersive x-ray spectroscopy (EDS) spectrum obviously demonstrated the presence of HfO2 NPs. Analysis and studies on the dielectric properties of the HfO2 NPs such as the dielectric constant, the dielectric loss, and alternating current (AC) conductivity were carried out at varying frequencies and temperatures.

Rare-earth hafnium oxide materials for magnetohydrodynamic (MHD) generator application

Energy Technology Data Exchange (ETDEWEB)

Marchant, D. D; Bates, J. L.

1979-01-01

Several ceramic materials based on rare-earth hafnium oxides have been identified as potential high-temperature electrodes and low-temperature current leadouts for open cycle coal-fired MHD generator channels. The electrode-current leadouts combination must operate at temperatures between 400 and 2000K with an electrical conductivity greater than 10/sup -2/ ohm/sup -1/ cm/sup -1/. The electrodes will be exposed to flowing (linear flow rates up to 100 m/s) potassium seeded coal combustion gases (plasma core temperatures between 2400 to 3200/sup 0/K) and coal slag. During operation the electrodes must conduct direct electric current at densities near 1.5 amp/cm/sup 2/. Consequently, the electrodes must be resistant to electrochemical decompositions and interactions with both the coal slag and potassium salts (e.g., K/sub 2/SO/sub 4/, K/sub 2/CO/sub 3/). The current leadout materials are placed between the hot electrodes and the water-cooled copper structural members and must have electrical conductivities greater than 10/sup -2/ ohm/sup -1/ cm/sup -1/ between 1400 and 400/sup 0/K. The current leadouts must be thermally and electrochemically compatible with the electrode, copper, and potassium salts. Ideally, the electrodes and current leadouts should exhibit minimal ionic conductivity. The fabrication, electrical conductivity, and electrochemical corrosion of rare-earth hafnium oxide materials are discussed. (WHK)

Hafnium isotope evidence for a transition in the dynamics of continental growth 3.2 Gyr ago.

Science.gov (United States)

Næraa, T; Scherstén, A; Rosing, M T; Kemp, A I S; Hoffmann, J E; Kokfelt, T F; Whitehouse, M J

2012-05-30

Earth's lithosphere probably experienced an evolution towards the modern plate tectonic regime, owing to secular changes in mantle temperature. Radiogenic isotope variations are interpreted as evidence for the declining rates of continental crustal growth over time, with some estimates suggesting that over 70% of the present continental crustal reservoir was extracted by the end of the Archaean eon. Patterns of crustal growth and reworking in rocks younger than three billion years (Gyr) are thought to reflect the assembly and break-up of supercontinents by Wilson cycle processes and mark an important change in lithosphere dynamics. In southern West Greenland numerous studies have, however, argued for subduction settings and crust growth by arc accretion back to 3.8 Gyr ago, suggesting that modern-day tectonic regimes operated during the formation of the earliest crustal rock record. Here we report in situ uranium-lead, hafnium and oxygen isotope data from zircons of basement rocks in southern West Greenland across the critical time period during which modern-like tectonic regimes could have initiated. Our data show pronounced differences in the hafnium isotope-time patterns across this interval, requiring changes in the characteristics of the magmatic protolith. The observations suggest that 3.9-3.5-Gyr-old rocks differentiated from a >3.9-Gyr-old source reservoir with a chondritic to slightly depleted hafnium isotope composition. In contrast, rocks formed after 3.2 Gyr ago register the first additions of juvenile depleted material (that is, new mantle-derived crust) since 3.9 Gyr ago, and are characterized by striking shifts in hafnium isotope ratios similar to those shown by Phanerozoic subduction-related orogens. These data suggest a transitional period 3.5-3.2 Gyr ago from an ancient (3.9-3.5 Gyr old) crustal evolutionary regime unlike that of modern plate tectonics to a geodynamic setting after 3.2 Gyr ago that involved juvenile crust generation by plate

The interaction of fast neutrons with hafnium

International Nuclear Information System (INIS)

Smith, A.B.

2002-01-01

Elemental hafnium neutron total cross sections are measured from ∼0.75 to 4.5 MeV in steps of ∼40 keV. Differential neutron elastic-scattering cross sections are measured from ∼4.5 to 10.0 MeV in ∼0.5 MeV steps and at 40 scattering angles distributed between ∼17 and 160 deg. These data are combined with those found in the literature to construct a comprehensive experimental data base which is interpreted in terms of coupled-channels models. Physical characteristics of the resulting potentials are discussed. Comparisons are made with ENDF/B-6 (MAT 7200). A detailed report of this work is given by Smith (Smith, A., 2001. Argonne National Laboratory Report ANL/NDM-153)

Reinforcement against crack propagation of PWR absorbers by development of boron-carbon-hafnium composites

International Nuclear Information System (INIS)

Provot, B.; Herter, P.

2000-01-01

In order to improve the mechanical behaviour of materials used as neutron absorbers in nuclear reactors, we have developed CERCER or CERMET composites with boron and hafnium. Thus a new composite B 4 C/HfB 2 has been especially studied. We have identified three kinds of degradation under irradiation (thermal gradient, swelling due to fission products and accidental corrosion) that induce imposed deformations cracking phenomena. Mechanical behaviour and crack propagation resistance have been studied by ball-on-three-balls and double torsion tests. A special device was developed to enable crack propagation and associated stress intensity factor measurements. Effects of structure and of a second phase are underline. First results show that these materials present crack initiation and propagation resistance much higher than pure boron carbide or hafnium diboride. We observe R-Curves effects, crack bridging or branching, crack arrests, and toughness increases that we can relate respectively to the composite structures. (author)

Titrimetric determination of thiocyanate in solutions of the hafnium-zirconium separation process

International Nuclear Information System (INIS)

Vazquez, Cristina; Botbol, Moises; Hernandez, M.H.

1980-01-01

The control of the thiocyanate concentration is necessary during the process of separating hafnium from zirconium by the hexone-thiocyanate method. Said control is carried out by titrimetric determination of thiocyanate in aqueous and organic solutions containing hydrochloric acid and ammonium thiocyanate in presence or absence of zirconium and/or hafnium. The method consists in a redox volumetric analysis using a cerium (IV) salt as titrating agent, and ferroine as the final point indicator. Owing to the instability of thiocyanate in an acid medium it is necessary to know previously if the decomposition of solutions with different concentration of ammonium thiocyanate and hydrochloric acid may have an influence upon the analytic results or may even invalidate them. In order to obtain reliable results, it must be taken into account that the stability of the solutions depends on the thiocyanate concentration, the acidity and the time elapsed from the moment the sample is taken until the test is performed. The decomposition process can be slowed down by cooling the solutions. This method allows to control the plant and does not require any special equipment. (M.E.L) [es

Synthesis and characterization of hafnium oxide for luminescent applications

International Nuclear Information System (INIS)

Guzman Mendoza, J.; Aguilar Frutis, M.A.; Flores, G. Alarcon; Garcia Hipolito, M.; Azorin Nieto, J.; Rivera Montalvo, T.; Falcony, C.

2008-01-01

Full text: Hafnium oxide (HfO 2 ) is a material with a wide range of possible technological applications because it's chemical and physical properties such as high melting point, high chemical stability, high refraction index, high dielectric constant and hardness near to diamond in the tetragonal phase. The large energy gap and low phonon frequencies of the HfO 2 makes it appropriate as a host matrix for been doped with rare earth activators. Efficient luminescent materials find wide application in electroluminescent flat panel displays; color plasma displays panels, scintillators, cathode ray tubes, fluorescent lamps, lasers, etc. In recent years the study of luminescent materials based on HfO 2 has been intensified. Some groups have studied the optical properties of doped and undoped HfO 2 . In this contribution, Hafnium Oxide (HfO 2 ) films were prepared using the spray pyrolysis deposition technique. The material was synthesized using chlorides as raw materials in deionised water as solvent and deposited on Corning glass substrates at temperatures from 300 deg C to 600 deg C. For substrate temperatures lower than 400 deg C, the deposited films are amorphous, while for substrate temperatures higher than 450 deg C, the monoclinic phase of HfO 2 appears. Scanning electron microscopy with microprobe analysis was use to observe the microstructure and obtain the chemical composition of the films; rough surfaces with spherical particles were appreciated. UV and low energy X Ray radiations were used in order to achieve the thermoluminescent characterization of the films as a function of the deposition temperature

Titanium, zirconium- and hafnium containing initiators in the polymerization of acrylic monomers to ''living'' polymers

International Nuclear Information System (INIS)

Farnham, W.B.; Hertler, W.R.

1988-01-01

This patent describes a process for preparing ''living'' polymer. The process comprises contacting one or more acrylic monomers under polymerizing conditions with a polymerization-initiating amount of a tetra-coordinate organotitanium, organozirconium or organo-hafnium polymerization initiator, and ''living'' polymers produced thereby

Zirconium and hafnium tetrachloride separation by extractive distillation with molten zinc chloride lead chloride solvent

International Nuclear Information System (INIS)

McLaughlin, D.F.; Stoltz, R.A.

1988-01-01

In an extractive distillation method for separating hafniuim tetrachloride from zirconium tetrachloride of the type wherein a mixture of zirconium and hafnium tetrachlorides is introduced into an extractive distillation column, which extractive distillation column has a reboiler connected at the bottom and a reflux condenser connected at the top and wherein a molten salt solvent is circulated into the reflux condenser and through the column to provide a liquid phase, and wherein molten salt solvent containing zirconium tetrachloride is taken from the reboiler and run through a stripper to remove zirconium tetrachloride product from the molten salt solvent and the stripped molten salt solvent is returned to the reflux condenser and hafnium tetrachloride enriched vapor is taken as product from the reflux condenser, the improvement is described comprising: the molten salt having a composition of at least 30 mole percent zinc chloride and at least 10 mole percent of lead chloride

Atomic layer deposition of calcium oxide and calcium hafnium oxide films using calcium cyclopentadienyl precursor

International Nuclear Information System (INIS)

Kukli, Kaupo; Ritala, Mikko; Sajavaara, Timo; Haenninen, Timo; Leskelae, Markku

2006-01-01

Calcium oxide and calcium hafnium oxide thin films were grown by atomic layer deposition on borosilicate glass and silicon substrates in the temperature range of 205-300 o C. The calcium oxide films were grown from novel calcium cyclopentadienyl precursor and water. Calcium oxide films possessed refractive index 1.75-1.80. Calcium oxide films grown without Al 2 O 3 capping layer occurred hygroscopic and converted to Ca(OH) 2 after exposure to air. As-deposited CaO films were (200)-oriented. CaO covered with Al 2 O 3 capping layers contained relatively low amounts of hydrogen and re-oriented into (111) direction upon annealing at 900 o C. In order to examine the application of CaO in high-permittivity dielectric layers, mixtures of Ca and Hf oxides were grown by alternate CaO and HfO 2 growth cycles at 230 and 300 o C. HfCl 4 was used as a hafnium precursor. When grown at 230 o C, the films were amorphous with equal amounts of Ca and Hf constituents (15 at.%). These films crystallized upon annealing at 750 o C, showing X-ray diffraction peaks characteristic of hafnium-rich phases such as Ca 2 Hf 7 O 16 or Ca 6 Hf 19 O 44 . At 300 o C, the relative Ca content remained below 8 at.%. The crystallized phase well matched with rhombohedral Ca 2 Hf 7 O 16 . The dielectric films grown on Si(100) substrates possessed effective permittivity values in the range of 12.8-14.2

Separation of zirconium--hafnium by nitride precipitation

International Nuclear Information System (INIS)

Anderson, R.N.; Parlee, N.A.

1977-01-01

A method is described for the separation of a light reactive metal (e.g., zirconium) from a heavy reactive metal (e.g., hafnium) by forming insoluble nitrides of the metals in a molten metal solvent (e.g., copper) inert to nitrogen and having a suitable density for the light metal nitride to form a separate phase in the upper portion of the solvent and for the heavy metal nitride to form a separate phase in the lower portion of the solvent. Nitriding is performed by maintaining a nitrogen-containing atmosphere over the bath. The light and heavy metals may be an oxide mixture and carbothermically reduced to metal form in the same bath used for nitriding. The nitrides are then separately removed and decomposed to form the desired separate metals. 16 claims, 1 figure

Modified method for zirconium or hafnium gravimetric determination with glycolic acid derivatives

International Nuclear Information System (INIS)

Barbieri, R.S.; Rocha, J.C.; Terra, V.R.; Marques Neto, A.

1989-01-01

The conditions for gravimetric determination of zirconium or hafnium by glicolic acid derivatives were studied by thermogravimetric analysis. The method utilized shown that after precipitation, washing and drying of precipitates at 150 0 C, the resulting solid was weighed in the form of [M{RCH(OH)COO} 4 ] (M = Zr,Hf;R = C 6 H 5 , β-C 10 H 7 ,p-BrC 6 H 4 ). (author) [pt

Correlations between nuclear data and integral slab experiments: the case of hafnium; Correlations entre donnees nucleaires et experiences integrales a plaques: le cas du hafnium

Energy Technology Data Exchange (ETDEWEB)

Palau, J M

1999-07-01

The aim of this work was to evaluate how much integral slab experiments can both reduce discrepancies between experimental results and calculations, and improve the knowledge of hafnium isotopes neutronic parameters by an adapted sensitivity and uncertainty method. A statistical approach, based on the generalized least squares method and perturbation theory, has been incorporated into our calculation system in order to deduce microscopic cross-section adjustments from observed integral measurements on this particular 'mock-up' reactor.In this study it has been established that the correlations between integral parameters and hafnium capture cross-sections enable specific variations in the region of resolved resonances at the level of multigroup and punctual cross-sections recommended data (JEF-2.2 evaluation) to be highlighted. The use of determinist methods together with Monte Carlo- type simulations enabled a depth analysis of the modelling approximations to be carried out. Furthermore, the sensitivity coefficient validation technique employed leads to a reliable assessment of the quality of the new basic nuclear data. In this instance, the adjustments proposed for certain isotope {sup 177}Hf resonance parameters reduce, after error propagation, by 3 to 5 per cent the difference between experimental results and calculations related to this absorbent's efficiency. Beyond this particular application, the qualification methodology integrated in our calculation system should enable other basic sizing parameters to be treated (chemical / geometric data or other unexplored nuclear data) to make technological requirements less stringent. (author)

Correlations between nuclear data and integral slab experiments: the case of hafnium; Correlations entre donnees nucleaires et experiences integrales a plaques: le cas du hafnium

Energy Technology Data Exchange (ETDEWEB)

Palau, J.M

1999-07-01

The aim of this work was to evaluate how much integral slab experiments can both reduce discrepancies between experimental results and calculations, and improve the knowledge of hafnium isotopes neutronic parameters by an adapted sensitivity and uncertainty method. A statistical approach, based on the generalized least squares method and perturbation theory, has been incorporated into our calculation system in order to deduce microscopic cross-section adjustments from observed integral measurements on this particular 'mock-up' reactor.In this study it has been established that the correlations between integral parameters and hafnium capture cross-sections enable specific variations in the region of resolved resonances at the level of multigroup and punctual cross-sections recommended data (JEF-2.2 evaluation) to be highlighted. The use of determinist methods together with Monte Carlo- type simulations enabled a depth analysis of the modelling approximations to be carried out. Furthermore, the sensitivity coefficient validation technique employed leads to a reliable assessment of the quality of the new basic nuclear data. In this instance, the adjustments proposed for certain isotope {sup 177}Hf resonance parameters reduce, after error propagation, by 3 to 5 per cent the difference between experimental results and calculations related to this absorbent's efficiency. Beyond this particular application, the qualification methodology integrated in our calculation system should enable other basic sizing parameters to be treated (chemical / geometric data or other unexplored nuclear data) to make technological requirements less stringent. (author)

On-line separation of refractory hafnium and tantalum isotopes at the ISOCELE separator

CERN Document Server

Liang, C F; Obert, J; Paris, P; Putaux, J C

1981-01-01

By chemical evaporation technique, neutron deficient hafnium nuclei have been on-line separated at the ISOCELE facility, from the isobar rare-earth elements, in the metal-fluoride HfF/sub 3//sup +/ ion form. Half-lives of /sup 162-165/Hf have been measured. Similarly, tantalum has been selectively separated on the TaF/sub 4//sup +/ form. (4 refs) .

Self-cleaning and surface chemical reactions during hafnium dioxide atomic layer deposition on indium arsenide.

Science.gov (United States)

Timm, Rainer; Head, Ashley R; Yngman, Sofie; Knutsson, Johan V; Hjort, Martin; McKibbin, Sarah R; Troian, Andrea; Persson, Olof; Urpelainen, Samuli; Knudsen, Jan; Schnadt, Joachim; Mikkelsen, Anders

2018-04-12

Atomic layer deposition (ALD) enables the ultrathin high-quality oxide layers that are central to all modern metal-oxide-semiconductor circuits. Crucial to achieving superior device performance are the chemical reactions during the first deposition cycle, which could ultimately result in atomic-scale perfection of the semiconductor-oxide interface. Here, we directly observe the chemical reactions at the surface during the first cycle of hafnium dioxide deposition on indium arsenide under realistic synthesis conditions using photoelectron spectroscopy. We find that the widely used ligand exchange model of the ALD process for the removal of native oxide on the semiconductor and the simultaneous formation of the first hafnium dioxide layer must be significantly revised. Our study provides substantial evidence that the efficiency of the self-cleaning process and the quality of the resulting semiconductor-oxide interface can be controlled by the molecular adsorption process of the ALD precursors, rather than the subsequent oxide formation.

Ground-state structures of Hafnium clusters

Energy Technology Data Exchange (ETDEWEB)

Ng, Wei Chun; Yoon, Tiem Leong [School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Lim, Thong Leng [Faculty of Engineering and Technoloty, Multimedia University, Melaca Campus, 75450 Melaka (Malaysia)

2015-04-24

Hafnium (Hf) is a very large tetra-valence d-block element which is able to form relatively long covalent bond. Researchers are interested to search for substitution to silicon in the semi-conductor industry. We attempt to obtain the ground-state structures of small Hf clusters at both empirical and density-functional theory (DFT) levels. For calculations at the empirical level, charge-optimized many-body functional potential (COMB) is used. The lowest-energy structures are obtained via a novel global-minimum search algorithm known as parallel tempering Monte-Carlo Basin-Hopping and Genetic Algorithm (PTMBHGA). The virtue of using COMB potential for Hf cluster calculation lies in the fact that by including the charge optimization at the valence shells, we can encourage the formation of proper bond hybridization, and thus getting the correct bond order. The obtained structures are further optimized using DFT to ensure a close proximity to the ground-state.

Molecular structure, vibrational, HOMO-LUMO, MEP and NBO analysis of hafnium selenite

Science.gov (United States)

Yankova, Rumyana; Genieva, Svetlana; Dimitrova, Ginka

2017-08-01

In hydrothermal condition hafnium selenite with estimated chemical composition Hf(SeO3)2·n(H2O) was obtained and characterized by powder X-Ray diffraction, IR spectroscopy and thermogravimetrical analysis. The composition of the obtained crystalline phase was established as dihydrate of tetraaqua complex of the hafnium selenite [Hf(SeO3)2(H2O)4]·2H2O. The results of the thermogravimetrical analysis are shown that the two hydrated water molecules are released in the temperature interval 80-110°C, while the four coordinated water molecules - at 210-300°C. By DFT method, with Becke's three parameter exchange-functional combined with gradient-corrected correlation functional of Lee, Yang and Parr and 6-31G(d), 6-311 + G(d,p) basis sets and LANL2DZ for Hf atom were calculated the molecular structure, vibrational frequencies and thermodynamic properties of the structure. The UV-Vis spectra and electronic properties are presented. The energy and oscillator strength calculated by time-dependent density functional theory corresponds well with the experimental ones. Molecular electrostatic potential (MEP) was performed. Mulliken population analysis on atomic charges was also calculated. The stability and intramolecular interactions are interpreted by NBO analysis.

Near net shape processing of zirconium or hafnium metals and alloys

International Nuclear Information System (INIS)

Evans, S.C.

1992-01-01

This patent describes a process for producing a metal shape. It comprises: plasma arc melting a metal selected from zirconium, hafnium and alloys thereof comprising at least about 90 w/o of these metals to form a liquid pool; pouring the metal form the pool into a mold to form a near net shape; and reducing the metal from its near net shape to a final size while maintaining the metal temperature below the alpha-beta transition temperature throughout the size reducing step

In-Pile Experiment of a New Hafnium Aluminide Composite Material to Enable Fast Neutron Testing in the Advanced Test Reactor

Energy Technology Data Exchange (ETDEWEB)

Donna Post Guillen; Douglas L. Porter; James R. Parry; Heng Ban

2010-06-01

A new hafnium aluminide composite material is being developed as a key component in a Boosted Fast Flux Loop (BFFL) system designed to provide fast neutron flux test capability in the Advanced Test Reactor. An absorber block comprised of hafnium aluminide (Al3Hf) particles (~23% by volume) dispersed in an aluminum matrix can absorb thermal neutrons and transfer heat from the experiment to pressurized water cooling channels. However, the thermophysical properties, such as thermal conductivity, of this material and the effect of irradiation are not known. This paper describes the design of an in-pile experiment to obtain such data to enable design and optimization of the BFFL neutron filter.

33 CFR 187.321 - What are the hull identification number (HIN) provisions?

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false What are the hull identification number (HIN) provisions? 187.321 Section 187.321 Navigation and Navigable Waters COAST GUARD, DEPARTMENT... Vessel Titling Systems § 187.321 What are the hull identification number (HIN) provisions? A State must...

Complexing of zirconium and hafnium with ortho-aminobenzoic acid and paraaminobenzoic acid

International Nuclear Information System (INIS)

Alekseeva, I.I.; Nemzer, I.I.; Yuranova, L.I.; Borisova, V.V.; Prozorovskaya, Z.N.

1977-01-01

Formation of complexes between zirconium and hafnium and ortho- and para-aminobenzoic acids has been studied by the kinetic method. It has been found that at pH=1.3-2.0 and concentrations of metals 10 -5 -10 -6 mole complex compounds are formed with composition Me:L=1:2 and 1:1 (Me=Zr, Hf; L=ortho- or para-aminobenzoic acids). Stepwise constants and overall effective constants of complex formation have been calculated

Correlations between nuclear data and results of integral slab experiments. Case of hafnium; Correlations entre donnees nucleaires et experiences integrales a plaques: le cas du hafnium

Energy Technology Data Exchange (ETDEWEB)

Palau, J M

1997-10-22

The aim of this thesis was to evaluate how much integral slab experiments can both reduce discrepancies between experimental results and calculations, and improve the knowledge of hafnium isotopes neutronic parameters by an adapted sensitivity and uncertainty method. A statistical approach, based on the generalized least squares method and perturbation theory, has been incorporated into our calculation system in order to deduce microscopic cross-section adjustments from observed integral measurements on this particular `mock-up` reactor. In this study it has been established that the correlations between integral parameters and hafnium capture cross-sections enable specific variations in the region of resolved resonances at the level of multigroup and punctual cross-sections recommended data (JEF-2.2 evaluation) to be highlighted. The use of determinist methods (APOLLO2 code) together with Monte Carlo- type simulations (TRIPOLI4 code) enabled a depth analysis of the modelling approximations to be carried out. Furthermore, the sensitivity coefficient validation technique employed leads to a reliable assessment of the quality of the new basic nuclear data. In this instance, the adjustments proposed for certain isotope {sup 177}Hf resonance parameters reduce, after error propagation, by 3 to 5 per cent the difference between experimental results and calculations related to this absorbent`s efficiency. Beyond this particular application, the qualification methodology integrated in our calculation system should enable other basic sizing parameters to be treated (chemical / geometric data or other unexplored nuclear data) to make technological requirements less stringent. (author) 128 refs.

High temperature thermodynamics of solutions of oxygen in zirconium and hafnium

International Nuclear Information System (INIS)

Boureau, G.; Gerdanian, P.

1984-01-01

The Tian-Calvet microcalorimetric method has been applied to the determination at 1323 Kelvin of ΔH(O 2 ), the partial molar enthalpy of mixing of oxygen in zirconium and in hafnium. No measurable departure from Henry's law has been found for dilute solutions (ratio oxygen over metal smaller than 0.1). For concentrated solutions repulsive interactions are found in agreement with the existence of ordered structures at lower temperatures. The domain of homogeneity of zirconium has been found larger than previously assumed. (author)

RDM lifetime measurements in 187Tl

International Nuclear Information System (INIS)

Chamoli, S.K.; Joshi, P.; Kumar, A.; Govil, I.M.; Mukherjee, G.; Singh, R.P.; Muralithar, S.; Bhowmik, R.K.

2003-01-01

The present work is an attempt to study the shape changes in 187 Tl through a measurement of electromagnetic transition probabilities of the high spin states. The Doppler shifted recoil distance technique was used to measure the lifetimes

Extraction of hafnium by 1-phenyl-3-methyl-4-benzoyl-5-pyralozone from aqueous-alcoholic solutions

International Nuclear Information System (INIS)

Hala, J.; Prihoda, J.

1975-01-01

Extraction of hafnium by 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HL) in benzene, toluene, chloroform and tetrachloromethane from aqueous-alcoholic solutions of the formal acidity of 2M-HClO 4 was studied. Methyl, ethyl, n- and isopropyl, tert-butyl and allyl alcohol as well as ethylene glycol monomethyl ether and propylene glycol were used as organic components of the mixed aqueous-organic phase. Their presence in some cases resulted in a synergic increase in the distribution ratio of hafnium. The increase is interpreted using the results of a slope analysis and measurements of the alcohol distribution and the relative permittivity of the organic phase. It is suggested that HfL 4 molecules were solvated by alcohol molecules in the organic phase. At high alcohol concentration synergism changed into antagonism. This was caused by changes in the distribution of HL and its interaction with the alcohol in the organic phase. (author)

Trap state passivation improved hot-carrier instability by zirconium-doping in hafnium oxide in a nanoscale n-metal-oxide semiconductor-field effect transistors with high-k/metal gate

International Nuclear Information System (INIS)

Liu, Hsi-Wen; Tsai, Jyun-Yu; Liu, Kuan-Ju; Lu, Ying-Hsin; Chang, Ting-Chang; Chen, Ching-En; Tseng, Tseung-Yuen; Lin, Chien-Yu; Cheng, Osbert; Huang, Cheng-Tung; Ye, Yi-Han

2016-01-01

This work investigates the effect on hot carrier degradation (HCD) of doping zirconium into the hafnium oxide high-k layer in the nanoscale high-k/metal gate n-channel metal-oxide-semiconductor field-effect-transistors. Previous n-metal-oxide semiconductor-field effect transistor studies demonstrated that zirconium-doped hafnium oxide reduces charge trapping and improves positive bias temperature instability. In this work, a clear reduction in HCD is observed with zirconium-doped hafnium oxide because channel hot electron (CHE) trapping in pre-existing high-k bulk defects is the main degradation mechanism. However, this reduced HCD became ineffective at ultra-low temperature, since CHE traps in the deeper bulk defects at ultra-low temperature, while zirconium-doping only passivates shallow bulk defects.

Determination of hafnium with the inductively coupled plasma (ICP)

International Nuclear Information System (INIS)

Wuensch, G.; Pose, K.

1985-01-01

The relative intensities of 198 hafnium lines in the Ar-ICP are listed. Spectral interference tables are given for the 9 analytically best lines, covering the range of +-60 pm around the Hf-lines. They include measured (not calculated) data of the interferent equivalent concentrations (IEC) and the critical concentration ratios (CCR) for 115 lines of all 34 possibly interfering elements. In many cases, these IEC- or CCR-data differ by 1 or 2 orders of magnitude from those calculated from intensities observed in the NBS-copper arc. Since no intense Hf-line is free from spectral interferences, examples are given for the calculation of the most suitable line for a known matrix. (orig.) [de

SIMS chemical and isotopic analysis of impact features from LDEF experiments AO187-1 and AO187-2

Science.gov (United States)

Stadermann, Frank J.; Amari, Sachiko; Foote, John; Swan, Pat; Walker, Robert M.; Zinner, Ernst

1995-01-01

Previous secondary ion mass spectrometry (SIMS) studies of extended impact features from LDEF capture cell experiment AO187-2 showed that it is possible to distinguish natural and man-made particle impacts based on the chemical composition of projectile residues. The same measurement technique has now been applied to specially prepared gold target impacts from experiment AO187-1 in order to identify the origins of projectiles that left deposits too thin to be analyzed by conventional energy-dispersive x-ray (EDX) spectroscopy. The results indicate that SIMS may be the method of choice for the analysis of impact deposits on a variety of sample surfaces. SIMS was also used to determine the isotopic compositions of impact residues from several natural projectiles. Within the precision of the measurements all analyzed residues show isotopically normal compositions.

26 CFR 1.187-2 - Definitions.

Science.gov (United States)

2010-04-01

... Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME TAX (CONTINUED) INCOME TAXES Itemized Deductions for Individuals and Corporations (continued) § 1.187-2 Definitions. (a) Certified coal mine safety equipment—(1) In general—(i) The term certified coal mine safety equipment means...

Atom-vacancy ordering and magnetic susceptibility of nonstoichiometric hafnium carbide

International Nuclear Information System (INIS)

Gusev, A.I.; Zyryanova, A.N.

1999-01-01

Experimental results on magnetic susceptibility of nonstoichiometric hafnium carbide HfC y (0.6 0.71 , HfC 0.78 and HfC 0.83 in the range of 870-930 K the anomalies are revealed which are associated with superstructure short-range ordering in a non-metallics sublattice. It is shown that a short-range order in HfC 0.71 and HfC 0.78 carbides corresponds to Hf 3 C 2 ordered phase, and in HfC 0.83 carbide - to Hf 6 C 5 ordered phase. HfC 0.78 carbide is found to possesses zero magnetic susceptibility in temperature range 910-980 K [ru

Hafnium carbide nanocrystal chains for field emitters

International Nuclear Information System (INIS)

Tian, Song; Li, Hejun; Zhang, Yulei; Ren, Jincui; Qiang, Xinfa; Zhang, Shouyang

2014-01-01

A hafnium carbide (HfC) nanostructure, i.e., HfC nanocrystal chain, was synthesized by a chemical vapor deposition (CVD) method. X-ray diffractometer, field-emission scanning electron microscope, transmission electron microscope, and energy-dispersive X-ray spectrometer were employed to characterize the product. The synthesized one-dimensional (1D) nanostructures with many faceted octahedral nanocrystals possess diameters of tens of nanometers to 500 nm and lengths of a few microns. The chain-like structures possess a single crystalline structure and preferential growth direction along the [1 0 0] crystal orientation. The growth of the chains occurred through the vapor–liquid–solid process along with a negative-feedback mechanism. The field emission (FE) properties of the HfC nanocrystal chains as the cold cathode emitters were examined. The HfC nanocrystal chains display good FE properties with a low turn-on field of about 3.9 V μm −1 and a high field enhancement factor of 2157, implying potential applications in vacuum microelectronics.

Simplified method for gravimetric determination of zirconium or hafnium with α-hydroxy carboxylic acids

International Nuclear Information System (INIS)

Barbieri, R.S.; Rocha, J.C.; Terra, V.R.; Marques Netto, A.

1989-01-01

The conditions for gravimetric determination of zirconium or hafnium by glicoloc acids derivatives were studied by thermogravimetric analysis. The method utilized shownd that after precipitation, washing and drying of precipitates at 150 o C, the resulting solid was weighed in the form of [M (RCH(OH)COO) 4 ] (M = Zr, Hf; R + C 6 H 5 , β-C 10 H 7 , p-BrC 6 H 4 ). (author)

Complexonometric determination of hafnium (4) in the presence of europium(3) or tantalum(5)

International Nuclear Information System (INIS)

Oziashvili, E.D.; Ehsakiya, K.E.; Sirakanyan, N.M.

1986-01-01

Complexonometric determination of hafnium in the presence of Ta or Eu in samples which can be decomposed by acids, i.e. in double borides has been investigated. Initial solutions are prepared by fusing with K 2 S 2 O 8 excess, the fusion was leached by hot water, H 2 SO L 4 was added and Hf was titrated by complexone 3 in the presence of xylenol orange

Investigation of interaction of zirconium and hafnium tetrafluorides with strontium fluoride

International Nuclear Information System (INIS)

Ratnikova, I.D.; Korenev, Yu.M.; Novoselova, A.V.

1980-01-01

Diagrams of the condensated state of systems SrF 2 -EF 4 have been plotted, where E represents Zr, Hf. In these systems, three intermediate compounds of Sr 3 EF 10 , Sr 2 EF 8 and Sr EF 6 compositions are formed. All those compounds melt incongruently at temperatures of 982, 865 and 750 deg C, respectively - zirconium salt; at temperatures of 1000, 900 and 820 deg C - hafnium salts. Fluoro-metallates of composition 2:1, and 1:1, exist in two polymorphic forms. Tetrafluorides were found to dissolve in strontium fluoride: they form solid solutions having fluorite structure

Correlations between nuclear data and integral slab experiments: the case of hafnium

International Nuclear Information System (INIS)

Palau, J.M.

1999-01-01

The aim of this work was to evaluate how much integral slab experiments can both reduce discrepancies between experimental results and calculations, and improve the knowledge of hafnium isotopes neutronic parameters by an adapted sensitivity and uncertainty method. A statistical approach, based on the generalized least squares method and perturbation theory, has been incorporated into our calculation system in order to deduce microscopic cross-section adjustments from observed integral measurements on this particular 'mock-up' reactor.In this study it has been established that the correlations between integral parameters and hafnium capture cross-sections enable specific variations in the region of resolved resonances at the level of multigroup and punctual cross-sections recommended data (JEF-2.2 evaluation) to be highlighted. The use of determinist methods together with Monte Carlo- type simulations enabled a depth analysis of the modelling approximations to be carried out. Furthermore, the sensitivity coefficient validation technique employed leads to a reliable assessment of the quality of the new basic nuclear data. In this instance, the adjustments proposed for certain isotope 177 Hf resonance parameters reduce, after error propagation, by 3 to 5 per cent the difference between experimental results and calculations related to this absorbent's efficiency. Beyond this particular application, the qualification methodology integrated in our calculation system should enable other basic sizing parameters to be treated (chemical / geometric data or other unexplored nuclear data) to make technological requirements less stringent. (author)

Laser coating of hafnium on Ti6Al4 for biomedical applications

CSIR Research Space (South Africa)

Phume, L

2012-12-01

Full Text Available Al4V FOR BIOMEDICAL APPLICATIONS Lerato Phume 1, 2, S.L. Pityana 1, 2, C. Meacock 1, A.P.I Popoola 2 1. National Laser Centre, Council for Scientific and Industrial Research, P.O. Box 395, Pretoria, 0001, South Africa 2. Department of Chemical... and Metallurgical Engineering, Tshwane University of Technology, Private Bag X 680, Pretoria, 0001, South Africa (b) (c) (e) To investigate laser surface coating of Ti6Al4V with preplaced Hafnium powder, to determine the influence of the energy density...

Preparation, structure and properties of hafnium compounds in the system Hf-C-N-O

International Nuclear Information System (INIS)

Brundiers, G.D.

1975-08-01

Highly dense, homogenous and single phase hafnium carbonitride samples (with low oxygen content) were prepared in the whole concentration range of the ternary cubic carbonitrides. Stoichiometric hafnium oxicarbides were also prepared within the range of solubility. The procedure involved the hot pressing of powders of HfC, HfN, Hf, Hf-Oxide and carbon at temperatures of 3,000 0 C and pressures up to 550 kpf/cm 2 using a novel technique. Small single crystals of slightly substoichiometric HfN were also repared. The densification of the powders was studied as a function of the non-metal concentration. Carbonitrides with N/Hf ratio of 0.37 were prepared in a high temperature autoclave operating at medium pressures by the reaction of HfC with nitrogen. All the samples were characterized by density measurements, chemical, X-ray and metallographic analysis and in some cases with the aid of quantitative metallography and microprobe analysis. Typical properties investigated were lattice parameter, thermal expansion, microhardness and electrical resistivity as function of the non-metal content. For specific concentrations extreme values in the properties are attained. With the aid of the valence electron concentration (VEC) parameter, the properties can be correlated with the density of states of electrons at the Fermi level. (orig./HK) [de

49 CFR 37.187 - Interline service.

Science.gov (United States)

2010-10-01

... an accessible bus or equivalent service to the passenger at Point B as the rules require. Operator Y... accessible bus to the passenger at Point B, any more than that it would be had the passenger directly... DISABILITIES (ADA) Over-the-Road Buses (OTRBs) § 37.187 Interline service. (a) When the general public can...

Systematic investigation of electromagnetic properties of all stable hafnium isotopes

International Nuclear Information System (INIS)

Napiorkowski, T.J.; Choinski, J.; Czosnyka, T.; Iwanicki, J.; Kownacki, J.; Zemlo, L.; Srebrny, J.; Starosta, K.; Boer, J. de.; Gollwitzer, A.; Loewe, M.; Wuerkner, M.; Guenther, C.; Weber, T.; Hagemann, G.; Sletten, G.

1996-01-01

In a systematic investigation of the electromagnetic structure of hafnium stable isotopes enriched targets of 176, 177, 178, 179, 180 Hf were Coulomb exciting using: 67 MeV 19 F beam from NBITAL FN Tandem, 125 MeV 32 S beam from MP Tandem in Accelerator Laboratory LMU and TU Munich, 225 MeV 58 Ni beam from NBITAL FN Tandem plus 2 Liniac Boosters complex. Scattered particle-gamma as well as p-γ-γ coincidence were registered. A further simultaneous analysis of Coulomb excitation cross section as a function of scattering angle of 19 F, 32 S, 58 Ni projectiles should be sufficient to deduce reduced probabilities of E2 transitions in ground state band

Highly substituted zirconium and hafnium cyclopentadienyl bifunctional β-diketiminate complexes – Synthesis, structure, and catalytic activity towards ethylene polymerization

Czech Academy of Sciences Publication Activity Database

Havlík, A.; Lamač, Martin; Pinkas, Jiří; Varga, Vojtěch; Růžička, A.; Olejník, R.; Horáček, Michal

2015-01-01

Roč. 786, JUN 2015 (2015), s. 71-80 ISSN 0022-328X R&D Projects: GA ČR GAP106/10/0924 Institutional support: RVO:61388955 Keywords : Zirconium * Hafnium * Cyclopentadienyl Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.336, year: 2015

Wake-up effects in Si-doped hafnium oxide ferroelectric thin films

International Nuclear Information System (INIS)

Zhou, Dayu; Xu, Jin; Li, Qing; Guan, Yan; Cao, Fei; Dong, Xianlin; Müller, Johannes; Schenk, Tony; Schröder, Uwe

2013-01-01

Hafnium oxide based ferroelectric thin films have shown potential as a promising alternative material for non-volatile memory applications. This work reports the switching stability of a Si-doped HfO 2 film under bipolar pulsed-field operation. High field cycling causes a “wake-up” in virgin “pinched” polarization hysteresis loops, demonstrated by an enhancement in remanent polarization and a shift of negative coercive voltage. The rate of wake-up is accelerated by either reducing the frequency or increasing the amplitude of the cycling field. We suggest de-pinning of domains due to reduction of the defect concentration at bottom electrode interface as origin of the wake-up

40 CFR 761.187 - Reporting importers and by persons generating PCBs in excluded manufacturing processes.

Science.gov (United States)

2010-07-01

...) MANUFACTURING, PROCESSING, DISTRIBUTION IN COMMERCE, AND USE PROHIBITIONS General Records and Reports § 761.187 Reporting importers and by persons generating PCBs in excluded manufacturing processes. In addition to... generating PCBs in excluded manufacturing processes. 761.187 Section 761.187 Protection of Environment...

Correlations between nuclear data and results of integral slab experiments. Case of hafnium

International Nuclear Information System (INIS)

Palau, J.M.

1997-01-01

The aim of this thesis was to evaluate how much integral slab experiments can both reduce discrepancies between experimental results and calculations, and improve the knowledge of hafnium isotopes neutronic parameters by an adapted sensitivity and uncertainty method. A statistical approach, based on the generalized least squares method and perturbation theory, has been incorporated into our calculation system in order to deduce microscopic cross-section adjustments from observed integral measurements on this particular 'mock-up' reactor. In this study it has been established that the correlations between integral parameters and hafnium capture cross-sections enable specific variations in the region of resolved resonances at the level of multigroup and punctual cross-sections recommended data (JEF-2.2 evaluation) to be highlighted. The use of determinist methods (APOLLO2 code) together with Monte Carlo- type simulations (TRIPOLI4 code) enabled a depth analysis of the modelling approximations to be carried out. Furthermore, the sensitivity coefficient validation technique employed leads to a reliable assessment of the quality of the new basic nuclear data. In this instance, the adjustments proposed for certain isotope 177 Hf resonance parameters reduce, after error propagation, by 3 to 5 per cent the difference between experimental results and calculations related to this absorbent's efficiency. Beyond this particular application, the qualification methodology integrated in our calculation system should enable other basic sizing parameters to be treated (chemical / geometric data or other unexplored nuclear data) to make technological requirements less stringent. (author)

Extraction of hafnium with chelating agents from aqueous-alcoholic solutions

International Nuclear Information System (INIS)

Hala, J.; Prihoda, J.

1975-01-01

The extraction was studied of hafnium into solutions of N-benzoyl-N-phenylhydroxylamine, 2-thenoyltrifluoroacetone and di-n-butylphosphoric acid in benzene, toluene, chloroform and tetrachloromethane from aqueous alcoholic solutions with a formal acidity of 2M-HClO 4 . Methyl-, ethyl-, n- and isopropyl- and tert-butyl alcohol were used as organic components in the mixed aqueous-organic phase. In the extraction into N-benzoyl-N-phenylhydroxylamine the presence of the alcohols resulted in synergic effects analogous to the previously described extraction by substituted benzoylpyrazolone. With the other two extractants, the effect of the alcohols was antagonistic, due to the interaction of alcohol or water with the reagent in the organic phase, and to the decrease in the reagent distribution constant. (author)

Studies of high-K isomers in hafnium nuclei

International Nuclear Information System (INIS)

Sletten, G.; Gjoerup, N.L.

1991-01-01

K-isomeric states built on high-Ω Nilsson orbitals from deformation-aligned high-j levels near the Fermi surface are found to cluster in the neutron rich Hf, W and Os nuclei. It has been shown that some of the high seniority states of this type have decay properties that indicate strong mixing of configurations and that in Osmium nuclei γ-softness cause strong deviations from the well established K-selection rule. Also in the Hafnium nuclei is the expected forbiddenness in isomeric decays an order of magnitude smaller than expected from the K-selection rule. A new 9 quasiparticle isomer has been discovered in 175 Hf at I=57/2. This isomer has the anomalous decay as the dominant mode. Other lower seniority states are also identified. At spin 35/2 and 45/2 the deformation aligned states become yrast, but the structure of the yrast line to even higher spins is not yet understood. (author)

Luminescent determination of zirconium and hafnium with myricetin

International Nuclear Information System (INIS)

Talipov, Sh.T.; Zel'tser, L.E.; Morozova, L.A.; Tashkhodzhaev, A.T.

1978-01-01

Reaction of formation of 3, 5, 7, 3', 4', 5' - hexaoxiflavone - myricetin complexes with zirconium and hafnium ions has been the basis for development of luminescent method of determining these elements. Optimum conditions for complexing have been determined. For Hf they are : 8-9 HCl concentration, maximum fluorescence wave length (lambda fl.)of 520 nm, wave length of exciting light (lambda el) of 436 nm, for Zr lambda fl = 536nm, lambda el = 436 nm. Stable fluorescence establishes after 25 min. for Zr and after 15 min for Hf in the presence of 40% ethanol. Usage of various camouflage agents has permitted to attain high selectivity of the method. Possibility for determination of Zr with myricetin in the presence of a 10-time excess of Hf, Cr, Cu, 50-time excess of Mo and Ti is shown. Sensitivity of Zr determination is 2.0x10 μg -2 /ml, for Hf it is 9.0x10 μg -3 and mineral waters

Amorphous Hafnium-Indium-Zinc Oxide Semiconductor Thin Film Transistors

Directory of Open Access Journals (Sweden)

Sheng-Po Chang

2012-01-01

Full Text Available We reported on the performance and electrical properties of co-sputtering-processed amorphous hafnium-indium-zinc oxide (α-HfIZO thin film transistors (TFTs. Co-sputtering-processed α-HfIZO thin films have shown an amorphous phase in nature. We could modulate the In, Hf, and Zn components by changing the co-sputtering power. Additionally, the chemical composition of α-HfIZO had a significant effect on reliability, hysteresis, field-effect mobility (μFE, carrier concentration, and subthreshold swing (S of the device. Our results indicated that we could successfully and easily fabricate α-HfIZO TFTs with excellent performance by the co-sputtering process. Co-sputtering-processed α-HfIZO TFTs were fabricated with an on/off current ratio of ~106, higher mobility, and a subthreshold slope as steep as 0.55 V/dec.

Molecular Characterization of the Plant Growth Promoting Bacterium Enterobacter sp. SA187 upon Contact with Arabidopsis thaliana

KAUST Repository

Alsharif, Wiam

2018-05-01

Salt stress is a severe environmental challenge in agriculture, limiting the quality and productivity of the crops around the globe. Plant growth promoting rhizobacteria (PGPR) is proposed as a friendly solution to overcome those challenges. The desert plant endophytic bacterium, Enterobacter sp. SA187 has shown plant growth promotion and salt stress tolerance beneficial effect on the model plant Arabidopsis thaliana in vitro as well as under the field conditions on different crops. SA187 has a distinguished morphology of yellow colonies (SA187Y) that could be due to carotenoid biosynthesis. However, the bacteria tend to lose the yellow color upon incubation with the plants and the colonies turn to white (SA187W). In comparison to SA187Y, SA187W shows 50% reduction on the beneficial impact on A. thaliana fresh and dry weight of root and shoot system. By counting the CFU/plant, we showed that SA187Y and SA187W both have similar colonization rate in both shoots and roots. Under non-salt conditions, optimal bacterial colonization was observed on day 8 after inocubation, however, under the salt stress condition, the optimal colonization was observed at day 4. Moreover, during the time period of the incubation of the SA187Y with the plants, there was a consistent noticeable loss of the yellow color of the colonies. This change in color is only observed eight days after transfer and the number of white colonies increases with the increase of the incubation time. In addition, SA187W was GFP-tagged by Tn7 transposon system and visualized by confocal laser scanning microscopy. The SA187W-GFP colonies have shown a similar colonization pattern as SA187Y-GFP, bacteria were colonizing the differentiation zone and cell elongation zone in the roots. Finally, the gene expression of the carotenoid biosynthesis pathways genes in SA187Y showed an overall higher gene expression compared to SA187W. In conclusion, the color loss seems to affect the beneficial impact of the bacteria on

Differential perturbed angular correlation: use of physico-chemical study of some hafnium complexes derivates of hydroxy acids and EDTA

International Nuclear Information System (INIS)

Silveira, J.G. da.

1981-01-01

Measures of quadrupolar interaction to nucleus level of the metal, in some hafnium complexes are presented, including the analysis by combustion, microanalysis, infrared spectroscopy and thermogravimetry. The hyperfine interaction parameters, the temperature effects and the thermal neutrons capture effects over the irradiated Hf Y (Y = EDTA) are also studied. (author)

Rhodium and Hafnium Influence on the Microstructure, Phase Composition, and Oxidation Resistance of Aluminide Coatings

OpenAIRE

Maryana Zagula-Yavorska; Małgorzata Wierzbińska; Jan Sieniawski

2017-01-01

A 0.5 μm thick layer of rhodium was deposited on the CMSX 4 superalloy by the electroplating method. The rhodium-coated superalloy was hafnized and aluminized or only aluminized using the Chemical vapour deposition method. A comparison was made of the microstructure, phase composition, and oxidation resistance of three aluminide coatings: nonmodified (a), rhodium-modified (b), and rhodium- and hafnium-modified (c). All three coatings consisted of two layers: the additive layer and the interdi...

Study of bulk Hafnium oxide (HfO2) under compression

Science.gov (United States)

Pathak, Santanu; Mandal, Guruprasad; Das, Parnika

2018-04-01

Hafnium oxide (HfO2) is a technologically important material. This material has K-value of 25 and band gap 5.8 eV. A k value of 25-30 is preferred for a gate dielectric [1]. As it shows good insulating and capacitive properties, HfO2 is being considered as a replacement to SiO2 in microelectronic devices as gate dielectrics. On the other hand because of toughening mechanism due to phase transformation induced by stress field observed in these oxides, HFO2 has been a material of investigations in various configurations for a very long time. However the controversies about phase transition of HfO2 under pressure still exists. High quality synchrotron radiation has been used to study the structural phase transition of HfO2 under pressure.

Hafnium at subduction zones: isotopic budget of input and output fluxes; L'hafnium dans les zones de subduction: bilan isotopique des flux entrant et sortant

Energy Technology Data Exchange (ETDEWEB)

Marini, J.Ch

2004-05-15

Subduction zones are the primary regions of mass exchanges between continental crust and mantle of Earth through sediment subduction toward the earth's mantle and by supply of mantellic magmas to volcanic arcs. We analyze these mass exchanges using Hafnium and Neodymium isotopes. At the Izu-Mariana subduction zone, subducting sediments have Hf and Nd isotopes equivalent to Pacific seawater. Altered oceanic crust has Hf and Nd isotopic compositions equivalent to the isotopic budget of unaltered Pacific oceanic crust. At Luzon and Java subduction zones, arc lavas present Hf isotopic ratios highly radiogenic in comparison to their Nd isotopic ratios. Such compositions of the Luzon and Java arc lavas are controlled by a contamination of their sources by the subducted oceanic sediments. (author)

Hafnium at subduction zones: isotopic budget of input and output fluxes

International Nuclear Information System (INIS)

Marini, J.Ch.

2004-05-01

Subduction zones are the primary regions of mass exchanges between continental crust and mantle of Earth through sediment subduction toward the earth's mantle and by supply of mantellic magmas to volcanic arcs. We analyze these mass exchanges using Hafnium and Neodymium isotopes. At the Izu-Mariana subduction zone, subducting sediments have Hf and Nd isotopes equivalent to Pacific seawater. Altered oceanic crust has Hf and Nd isotopic compositions equivalent to the isotopic budget of unaltered Pacific oceanic crust. At Luzon and Java subduction zones, arc lavas present Hf isotopic ratios highly radiogenic in comparison to their Nd isotopic ratios. Such compositions of the Luzon and Java arc lavas are controlled by a contamination of their sources by the subducted oceanic sediments. (author)

14 CFR 187.15 - Payment of fees.

Science.gov (United States)

2010-01-01

... REGULATIONS FEES § 187.15 Payment of fees. (a) The fees of this part are payable to the Federal Aviation Administration by check, money order, wire transfers, draft, payable in U.S. currency and drawn on a U.S. bank, or by credit card payable in U.S. currency, prior to the provision of any service under this part. (b...

Thermal expansion studies on Hafnium titanate (HfTiO4)

International Nuclear Information System (INIS)

Panneerselvam, G.; Subramanian, G.G.S.; Antony, M.P.

2006-01-01

The lattice thermal expansion characteristics of hafnium titanate (HfTiO 4 ) have been studied by measuring the lattice parameter as a function of temperature by high temperature X-ray diffraction technique (HT-XRD) in the temperature range 298-1973K. Percentage linear thermal expansion and mean linear thermal expansion coefficients were computed from the lattice parameter data. The thermal expansion of HfTiO 4 is highly anisotropic. The expansivity along 'a' axis is large; as compared to the expansivity along 'b' axis which is negative below 1073 K. The percentage linear thermal expansion in the temperature range 298-1973 K along a, b and c axis are 2.74, 0.901 and 1.49 respectively. Thermal expansion values obtained in the present study are in reasonable agreement with the existing thermal expansion data. (author)

Surface State Capture Cross-Section at the Interface between Silicon and Hafnium Oxide

Directory of Open Access Journals (Sweden)

Fu-Chien Chiu

2013-01-01

Full Text Available The interfacial properties between silicon and hafnium oxide (HfO2 are explored by the gated-diode method and the subthreshold measurement. The density of interface-trapped charges, the current induced by surface defect centers, the surface recombination velocity, and the surface state capture cross-section are obtained in this work. Among the interfacial properties, the surface state capture cross-section is approximately constant even if the postdeposition annealing condition is changed. This effective capture cross-section of surface states is about 2.4 × 10−15 cm2, which may be an inherent nature in the HfO2/Si interface.

A thermally robust and thickness independent ferroelectric phase in laminated hafnium zirconium oxide

Directory of Open Access Journals (Sweden)

S. Riedel

2016-09-01

Full Text Available Ferroelectric properties in hafnium oxide based thin films have recovered the scaling potential for ferroelectric memories due to their ultra-thin-film- and CMOS-compatibility. However, the variety of physical phenomena connected to ferroelectricity allows a wider range of applications for these materials than ferroelectric memory. Especially mixed HfxZr1-xO2 thin films exhibit a broad compositional range of ferroelectric phase stability and provide the possibility to tailor material properties for multiple applications. Here it is shown that the limited thermal stability and thick-film capability of HfxZr1-xO2 can be overcome by a laminated approach using alumina interlayers.

Influence of plastic deformation on nitriding of a molybdenum-hafnium alloy

International Nuclear Information System (INIS)

Lakhtin, Yu.M.; Kogan, Ya.D.; Shashkov, D.P.; Likhacheva, T.E.

1982-01-01

The influence of a preliminary plastic strain on the structure and properties of molybdenum alloy with 0.2 wt.% Hf upon nitriding in the ammonia medium at 900-1200 deg C during 1-6 h is investigated. The study of microhardness distribution across the nitrided layer thickness has shown that with increase of the degree of preliminary plastic strain up to 50 % the nitrided layer hardness decreases and with further reduction growth up to 90 % - increases. Nitriding sharply (hundred times) increases wear resistance of molybdenum alloy with hafnium addition. At the reduction degree 25 % the wear resistance is less than at other values of percentage reduction in area owing to the minimum thickness of the nitride zone. The alloy strained before nitriding by 25 % has shown the best results during heat resistance testing

Dielectric response and ac conductivity analysis of hafnium oxide nanopowder

International Nuclear Information System (INIS)

Karahaliou, P K; Xanthopoulos, N; Krontiras, C A; Georga, S N

2012-01-01

The dielectric response of hafnium oxide nanopowder was studied in the frequency range of 10 -2 -10 6 MHz and in the temperature range of 20-180 °C. Broadband dielectric spectroscopy was applied and the experimental results were analyzed and discussed using the electric modulus (M*) and alternating current (ac) conductivity formalisms. The analyses of the dc conductivity and electric modulus data revealed the presence of mechanisms which are thermally activated, both with almost the same activation energy of 1.01 eV. A fitting procedure involving the superposition of the thermally activated dc conductivity, the universal dielectric responce and the near constant loss terms has been used to describe the frequency evolution of the real part of the specific electrical conductivity. The conductivity master curve was obtained, suggesting that the time-temperature superposition principle applies for the studied system, thus implying that the conductivity mechanisms are temperature independent.

Interface and oxide traps in high-κ hafnium oxide films

International Nuclear Information System (INIS)

Wong, H.; Zhan, N.; Ng, K.L.; Poon, M.C.; Kok, C.W.

2004-01-01

The origins of the interface trap generation and the effects of thermal annealing on the interface and bulk trap distributions are studied in detail. We found that oxidation of the HfO 2 /Si interface, removal of deep trap centers, and crystallization of the as-deposited film will take place during the post-deposition annealing (PDA). These processes will result in the removal of interface traps and deep oxide traps and introduce a large amount of shallow oxide traps at the grain boundaries of the polycrystalline film. Thus, trade-off has to be made in considering the interface trap density and oxide trap density when conducting PDA. In addition, the high interface trap and oxide trap densities of the HfO 2 films suggest that we may have to use the SiO 2 /HfO 2 stack or hafnium silicate structure for better device performance

Effects of oxygen partial pressure and annealing temperature on the residual stress of hafnium oxide thin-films on silicon using synchrotron-based grazing incidence X-ray diffraction

Energy Technology Data Exchange (ETDEWEB)

Biswas, Debaleen [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India); Sinha, Anil Kumar [ISU, Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India); Homi Bhabha National Institute, BARC, Mumbai 400 094 (India); Chakraborty, Supratic, E-mail: supratic.chakraborty@saha.ac.in [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India)

2016-10-30

Highlights: • Residual stress estimation thin hafnium oxide film with thickness of <10 nm. • A mathematical expression is proposed for stress estimation of thin-film using GIXRD. • Residual stress varies with argon content in Ar/O{sub 2} plasma and annealing temperature. • Variation of stress is explained by IL swelling and enhanced structural relaxation. - Abstract: Synchrotron radiation-based grazing incidence X-ray diffraction (GI-XRD) technique is employed here to estimate the residual stress of < 10 nm thin hafnium oxide film deposited on Si (100) substrate at different argon/oxygen ratios using reactive rf sputtering. A decrease in residual stress, tensile in nature, is observed at higher annealing temperature for the samples deposited with increasing argon ratio in the Ar/O{sub 2} plasma. The residual stress of the films deposited at higher p{sub Ar} (Ar:O{sub 2} = 4:1) is also found to be decreased with increasing annealing temperature. But the stress is more or less constant with annealing temperature for the films deposited at lower Ar/O{sub 2} (1:4) ratio. All the above phenomena can be explained on the basis of swelling of the interfacial layer and enhanced structural relaxation in the presence of excess Hf in hafnium oxide film during deposition.

Pyroelectricity of silicon-doped hafnium oxide thin films

Science.gov (United States)

Jachalke, Sven; Schenk, Tony; Park, Min Hyuk; Schroeder, Uwe; Mikolajick, Thomas; Stöcker, Hartmut; Mehner, Erik; Meyer, Dirk C.

2018-04-01

Ferroelectricity in hafnium oxide thin films is known to be induced by various doping elements and in solid-solution with zirconia. While a wealth of studies is focused on their basic ferroelectric properties and memory applications, thorough studies of the related pyroelectric properties and their application potential are only rarely found. This work investigates the impact of Si doping on the phase composition and ferro- as well as pyroelectric properties of thin film capacitors. Dynamic hysteresis measurements and the field-free Sharp-Garn method were used to correlate the reported orthorhombic phase fractions with the remanent polarization and pyroelectric coefficient. Maximum values of 8.21 µC cm-2 and -46.2 µC K-1 m-2 for remanent polarization and pyroelectric coefficient were found for a Si content of 2.0 at%, respectively. Moreover, temperature-dependent measurements reveal nearly constant values for the pyroelectric coefficient and remanent polarization over the temperature range of 0 ° C to 170 ° C , which make the material a promising candidate for IR sensor and energy conversion applications beyond the commonly discussed use in memory applications.

Implantation of titanium, chromium, yttrium, molybdenum, silver, hafnium, tantalum, tungsten and platinum ions generated by a metal vapor vacuum ion source into 440C stainless steel

International Nuclear Information System (INIS)

Sasaki, Jun; Hayashi, Kazunori; Sugiyama, Kenji; Ichiko, Osami; Hashiguchi, Yoshihiro

1992-01-01

Titanium, yttrium, molybdenum, silver, chromium, hafnium, tantalum, tungsten and platinum ions generated by a metal vapor vacuum arc (MEVVA) ion source were implanted into 440C stainless steel in the dose region 10 17 ions cm -2 with extraction voltages of up to 70 kV. Glow discharge spectroscopy (GDS), friction coefficient, and Vickers microhardness of the specimens were studied. Grooves made by friction tests were investigated by electron probe microanalysis (EPMA). GDS showed incorporation of carbon in the yttrium, hafnium, tantalum, tungsten and platinum implanted specimens, as well as titanium implanted samples. A large amount of oxygen was observed in the yttrium implanted specimen. The friction coefficient was measured by reciprocating sliding of an unimplanted 440C ball without lubricant at a load of 0.245 N. The friction decreased and achieved a stable state after implantation of titanium, hafnium and tantalum. The friction coefficient of the platinum implanted specimen showed a gradual decrease after several cycles of sliding at high friction coefficient. The yttrium implanted sample exhibited a decreased but slightly unstable friction coefficient. Results from EPMA showed that the implanted elements, which gave decreased friction, remained even after sliding of 200 cycles. Implantation of chromium, molybdenum, silver and tungsten did not provide a decrease in friction and the implants were gone from the wear grooves after the sliding tests. (orig.)

187Os-186Os and He Isotope Systematics of Iceland Picrites

Science.gov (United States)

Brandon, A. D.; Brandon, A. D.; Graham, D.; Gautason, B.

2001-12-01

Iceland is one of the longest-lived modern plumes, and seismic imaging supports a model where the roots of this plume are at the base of the lower mantle. Hence, Os isotopic data for lavas from this plume are ideal for further testing the role of core-mantle chemical exchange at the site of plume generation in the lower mantle, and for addressing the origin of Os-He isotopic variation in plumes. Recent work has shown that lavas from some plume systems (Hawaii, Noril'sk-Siberia, Gorgona) show coupled enrichments in 186Os/188Os and 187Os/188Os, not observed in upper mantle materials including abyssal peridotites. Picrites from Hawaii display a positive correlation between 186Os/188Os and He isotopes (R/Ra), where range in 186Os/188Os of 0.119834+/-28 to 0.1198475+/-29 and corresponding R/Ra from +7 to +25. These systematics are consistent with a lower mantle source for the radiogenic 186Os signal in the Hawaiian plume. The coupled Os enrichments in these plumes has been attributed to core-mantle chemical exchange, consistent with generation of the Hawaiian plume at the base of the lower mantle in D". Other potentially viable models await additional scrutiny. New He isotope and high precision 186Os/188Os and 187Os/188Os measurements for Iceland picrites show unique systematics compared to Hawaii. These picrites have 187Os/188Os ranging from 0.1297 to 0.1381 and R/Ra of +9 to +18, with generally higher R/Ra correlating with higher 187Os/188Os. Unlike the Hawaiian picrites from Hualalai and Loihi, which have coupled enrichments in 186Os/188Os and 187Os/188Os, the Iceland picrites show no enrichment 186Os/188Os - 0.1198363+/-28 (2s, n=14). Such Os-He isotopic variations require one end-member source that has high R/Ra, coupled with a long term elevated Re/Os and Pt/Os similar to that of the upper mantle. These systematics are inconsistent with either known upper mantle materials or those purported for ancient recycled slabs and may be a previously unidentified component

Critical evaluation of the determination of zirconium and hafnium by instrumental and radiochemical neutron activation analysis

International Nuclear Information System (INIS)

Burger, Mario; Kraehenbuehl, Urs

1991-01-01

Neutron activation analysis (instrument or radiochemical) is suitable for the determination of zirconium and hafnium in samples of geochemical origin only when sufficient attention is paid to inter-fering nuclides. The size of the necessary correction for INAA depends on the composition of the sample; this problem is discussed. The radio-chemical technique which is recommended involves separation of the samples, precipitations and anion-exchange separation. Results are given for various standard reference materials and for meteorites. (author). 12 refs.; 1 fig.; 9 tabs

Study of the odd mass transition nuclei: 185Hg, 187Hg, 189Hg and 183Ir

International Nuclear Information System (INIS)

Zerrouki, A.

1979-01-01

The radioactive decay of 185 Tl, 186 Tl, 187 Tl has been studied on the isotope separator Isocele II working on line with the Orsay synchrocyclotron from Au( 3 He,xn) reactions: the emitted α lines have been measured and the main γ lines belonging to the 187 Tl→ 187 Hg decay have been identified. The 185 Hg, 187 Hg, 189 Hg high spin states have been studied using the following (HI,xn) reactions obtained on the Strasbourg MP Tandem: 168 Er( 24 Mg,xn) 187 Hg, 188 Hg, 166 Er( 24 Mg,xn) 185 Hg, 186 Hg, 157 Gd( 32 S,xn) 184 Hg, 185 Hg, 158 Gd( 32 S,5n) 185 Hg and 175 Lu( 19 F,5n) 189 Hg. The excitation functions are indicated and a high spin level scheme of 189 Hg is proposed: it is compared to the 'quasiparticle + triaxial rotor' model predictions. A level scheme of 183 Ir is proposed from the data collected at Isolde II (CERN) by Dr. SCHUCK: it is analysed within the framework of the same theoretical model used above [fr

14 CFR Appendix B to Part 187 - Fees for FAA Services for Certain Flights

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Fees for FAA Services for Certain Flights B... (CONTINUED) ADMINISTRATIVE REGULATIONS FEES Pt. 187, App. B Appendix B to Part 187—Fees for FAA Services for... pay a fee for the FAA's rendering or providing certain services, including but not limited to the...

Spectroscopy of {sup 189,187}Pb from gamma-FMA coincidences

Energy Technology Data Exchange (ETDEWEB)

Janssens, R.V.F.; Davids, C.N.; Blumenthal, D. [and others

1995-08-01

The very neutron-deficient Pb isotopes are of much current interest because they exhibit shape coexistence between a spherical groundstate and a deformed prolate excited configuration located very low in excitation energy. Last year the nucleus {sup 186}Pb was studied at the FMA in an FMA-{gamma}-{gamma} coincidence experiment. The purpose of the present measurement was to delineate, for the first time, the groundstate and near groundstate excitations in the odd Pb isotopes {sup 189,187}Pb in order to identify the orbitals which have an important role in driving the nuclear shape. The experiment was performed only very recently at the FMA with 10 Compton-suppressed Ge detectors from the Argonne Notre Dame BGO Gamma-Ray facility. {sup 187}Pb was studied with the {sup 155}Gd({sup 36}Ar,4n) reaction at 179 MeV, while {sup 189}Pb was reached with the {sup 158}Gd({sup 36}Ar,5n) reaction at the same beam energy. The analysis just began. It can already be stated that transitions in both Pb isotopes were identified and that it should be possible to establish level schemes. The presence of possible isomeric states in {sup 189}Pb will be checked in a follow-up experiment planned in Canberra. A similar measurement on {sup 187}Pb appears very difficult because of the very small cross section involved.

A fast response hafnium selective polymeric membrane electrode based on N,N'-bis(α-methyl-salicylidene)-dipropylenetriamine as a neutral carrier

International Nuclear Information System (INIS)

Rezaei, B.; Meghdadi, S.; Zarandi, R. Fazel

2008-01-01

In this study a new hafnium selective sensor was fabricated from polyvinylchloride (PVC) matrix membrane containing neutral carrier N,N'-bis(α-methyl-salicylidene)-dipropylenetriamine (Mesaldpt) as a new ionophore, sodium tetraphenyl borate (NaTPB) as anionic discriminator and dioctyl phthalate (DOP) as plasticizing solvent mediator in tetrahydrofuran solvent. The electrode exhibits Nernstian response for Hf 4+ (Hafnium(IV)) over a wide concentration range (2.0 x 10 -7 to 1.0 x 10 -1 M) with the determination coefficient of 0.9966 and slope of 15.1 ± 0.1 mV decades -1 . The limit of detection is 1.9 x 10 -7 M. The electrode has a fast response time of 18 s and a working pH range of 4-8. The proposed membrane shows excellent discriminating ability towards Hf 4+ ion with regard to several alkali, alkaline earth transition and heavy metal ions. It can be used over a period of 1.5 months with good reproducibility. It is successfully applied for direct determination of Hf 4+ in solutions by standard addition method for real sample analysis

Study of hafnium (IV) oxide nanoparticles synthesized by polymerized complex and polymer precursor derived sol-gel methods

KAUST Repository

Ramos-Gonzá lez, R.; Garcí a-Cerda, L. A.; Alshareef, Husam N.; Gnade, Bruce E.; Quevedo-Ló pez, Manuel Angel Quevedo

2010-01-01

This work reports the preparation and characterization of hafnium (IV) oxide (HfO2) nanoparticles grown by derived sol-gel routes that involves the formation of an organic polymeric network. A comparison between polymerized complex (PC) and polymer precursor (PP) methods is presented. For the PC method, citric acid (CA) and ethylene glycol (EG) are used as the chelating and polymerizable reagents, respectively. In the case of PP method, poly(acrylic acid) (PAA) is used as the chelating reagent. In both cases, different precursor gels were prepared and the hafnium (IV) chloride (HfCl4) molar ratio was varied from 0.1 to 1.0 for the PC method and from 0.05 to 0.5 for the PP method. In order to obtain the nanoparticles, the precursors were heat treated at 500 and 800 °C. The thermal characterization of the precursor gels was carried out by thermogravimetric analysis (TGA) and the structural and morphological characterization by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD patterns of the samples obtained by both methods shows the formation of HfO2 at 500 °C with monoclinic crystalline phase. The PC method exhibited also the cubic phase. Finally, the HfO2 nanoparticles size (4 to 11 nm) was determined by TEM and XRD patterns. © (2010) Trans Tech Publications.

Study of hafnium (IV) oxide nanoparticles synthesized by polymerized complex and polymer precursor derived sol-gel methods

KAUST Repository

Ramos-González, R.

2010-03-01

This work reports the preparation and characterization of hafnium (IV) oxide (HfO2) nanoparticles grown by derived sol-gel routes that involves the formation of an organic polymeric network. A comparison between polymerized complex (PC) and polymer precursor (PP) methods is presented. For the PC method, citric acid (CA) and ethylene glycol (EG) are used as the chelating and polymerizable reagents, respectively. In the case of PP method, poly(acrylic acid) (PAA) is used as the chelating reagent. In both cases, different precursor gels were prepared and the hafnium (IV) chloride (HfCl4) molar ratio was varied from 0.1 to 1.0 for the PC method and from 0.05 to 0.5 for the PP method. In order to obtain the nanoparticles, the precursors were heat treated at 500 and 800 °C. The thermal characterization of the precursor gels was carried out by thermogravimetric analysis (TGA) and the structural and morphological characterization by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD patterns of the samples obtained by both methods shows the formation of HfO2 at 500 °C with monoclinic crystalline phase. The PC method exhibited also the cubic phase. Finally, the HfO2 nanoparticles size (4 to 11 nm) was determined by TEM and XRD patterns. © (2010) Trans Tech Publications.

Complete Genome Sequence Analysis of Enterobacter sp. SA187, a Plant Multi-Stress Tolerance Promoting Endophytic Bacterium

KAUST Repository

Andres-Barrao, Cristina; Lafi, Feras Fawzi; Alam, Intikhab; Zé licourt, Axel de; Eida, Abdul Aziz; Bokhari, Ameerah; Alzubaidy, Hanin S.; Bajic, Vladimir B.; Hirt, Heribert; Saad, Maged

2017-01-01

Enterobacter sp. SA187 is an endophytic bacterium that has been isolated from root nodules of the indigenous desert plant Indigofera argentea. SA187 could survive in the rhizosphere as well as in association with different plant species, and was able to provide abiotic stress tolerance to Arabidopsis thaliana. The genome sequence of SA187 was obtained by using Pacific BioScience (PacBio) single-molecule sequencing technology, with average coverage of 275X. The genome of SA187 consists of one single 4,429,597 bp chromosome, with an average 56% GC content and 4,347 predicted protein coding DNA sequences (CDS), 153 ncRNA, 7 rRNA, and 84 tRNA. Functional analysis of the SA187 genome revealed a large number of genes involved in uptake and exchange of nutrients, chemotaxis, mobilization and plant colonization. A high number of genes were also found to be involved in survival, defense against oxidative stress and production of antimicrobial compounds and toxins. Moreover, different metabolic pathways were identified that potentially contribute to plant growth promotion. The information encoded in the genome of SA187 reveals the characteristics of a dualistic lifestyle of a bacterium that can adapt to different environments and promote the growth of plants. This information provides a better understanding of the mechanisms involved in plant-microbe interaction and could be further exploited to develop SA187 as a biological agent to improve agricultural practices in marginal and arid lands.

Complete Genome Sequence Analysis of Enterobacter sp. SA187, a Plant Multi-Stress Tolerance Promoting Endophytic Bacterium

KAUST Repository

Andres-Barrao, Cristina

2017-10-20

Enterobacter sp. SA187 is an endophytic bacterium that has been isolated from root nodules of the indigenous desert plant Indigofera argentea. SA187 could survive in the rhizosphere as well as in association with different plant species, and was able to provide abiotic stress tolerance to Arabidopsis thaliana. The genome sequence of SA187 was obtained by using Pacific BioScience (PacBio) single-molecule sequencing technology, with average coverage of 275X. The genome of SA187 consists of one single 4,429,597 bp chromosome, with an average 56% GC content and 4,347 predicted protein coding DNA sequences (CDS), 153 ncRNA, 7 rRNA, and 84 tRNA. Functional analysis of the SA187 genome revealed a large number of genes involved in uptake and exchange of nutrients, chemotaxis, mobilization and plant colonization. A high number of genes were also found to be involved in survival, defense against oxidative stress and production of antimicrobial compounds and toxins. Moreover, different metabolic pathways were identified that potentially contribute to plant growth promotion. The information encoded in the genome of SA187 reveals the characteristics of a dualistic lifestyle of a bacterium that can adapt to different environments and promote the growth of plants. This information provides a better understanding of the mechanisms involved in plant-microbe interaction and could be further exploited to develop SA187 as a biological agent to improve agricultural practices in marginal and arid lands.

Rapid formation of nanocrystalline HfO2 powders from amorphous hafnium hydroxide under ultrasonically assisted hydrothermal treatment

International Nuclear Information System (INIS)

Meskin, Pavel E.; Sharikov, Felix Yu.; Ivanov, Vladimir K.; Churagulov, Bulat R.; Tretyakov, Yury D.

2007-01-01

Peculiarities of hafnium hydroxide hydrothermal decomposition were studied by in situ heat flux calorimetry for the first time. It was shown that this process occurs in one exothermal stage (ΔH = -17.95 kJ mol -1 ) at 180-250 deg. C resulting in complete crystallization of amorphous phase with formation of pure monoclinic HfO 2 . It was found that the rate of m-HfO 2 formation can be significantly increased by combining hydrothermal treatment with simultaneous ultrasonic activation

Improvement of aging kinetics and precipitate size refinement in Mg–Sn alloys by hafnium additions

Energy Technology Data Exchange (ETDEWEB)

Behdad, S. [Department of Mechanical and Materials Engineering, Florida International University, Miami, FL 33174 (United States); Zhou, L. [Department of Materials Science and Engineering and Advanced Materials Processing and Analysis Center, University of Central Florida, Orlando, FL 32816 (United States); Henderson, H.B.; Manuel, M.V. [Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611 (United States); Sohn, Y. [Department of Materials Science and Engineering and Advanced Materials Processing and Analysis Center, University of Central Florida, Orlando, FL 32816 (United States); Agarwal, A. [Department of Mechanical and Materials Engineering, Florida International University, Miami, FL 33174 (United States); Boesl, B., E-mail: bboesl@fiu.edu [Department of Mechanical and Materials Engineering, Florida International University, Miami, FL 33174 (United States)

2016-01-10

Two Mg–Sn alloys were microalloyed by addition of Hafnium and their age-hardening response was studied at 200 °C. Time to reach peak hardness was significantly reduced and improved by Hf addition. TEM study showed Hf clusters in the close vicinity and at the surface of Mg{sub 2}Sn precipitates, which confirms that Hf clusters act as additional nucleation centers for Mg{sub 2}Sn precipitate formation. Our results support the validity of thermokinetic criterion proposed by Mendis for selection of microalloying elements in order to refine precipitate size, accelerate aging kinetics and enhance peak hardness.

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

Science.gov (United States)

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.

Solvent extraction of hafnium(IV) by dinonylnaphthalene sulfonic acid from mixed aqueous-organic media

International Nuclear Information System (INIS)

Hala, J.; Piperkovova, H.

1979-01-01

The extraction of hafnium(IV) by heptane and toluene solutions of dinonylnaphthalene sulfonic acid (HD) from mixed aqueous-organic solutions has been studied. Alcohols, ketones, carboxylic acids, cyclic ethers, dimethylsulfoxide and dimethylformamide were used as the organic component of the mixed phase. Methanol, ethanol, formic acid and dioxane increased the extractability of Hf(IV) whereas other solvents showed only an antagonistic effect. The results were discussed from the point of view of the changes in micellar structure of HD, and compared with the uptake of Hf(IV) by resinous cation exchangers. The solubilization by HD of alcohols, carboxylic acids and dimethylsulfoxide was demonstrated by using the corresponding 14 C and 35 S labelled compounds. (author)

Effects of ICRF-187 and L-Carnitine on bleomycin-induced lung toxicity in rats

International Nuclear Information System (INIS)

Shouman, Samia A.; Abdel-Hamid, M.A.; Hassan, Zeinab A.; Mansour, Heba H.

2002-01-01

The possible modulatory effects of ICRF-187 and L-carnitine against bleomycin-induced pulmonary toxicity in male rats were investigated. Repeated administration of bleomycin (10 mg/kg, twice weekly for 6 consecutive weeks) produced significant lung toxicity. The toxicity was manifested by significant increase in normal contents of lipid peroxide (LPO, 91.7%) reduced glutathione (GSH, 73.2%) and oxidized glutathione (GSSG, 135.4%) as well as the activity of superoxide dismutase (SOD, 222.7%). Thirty minutes prior to bleomycin treatment, other groups of rats received either ICRF-187 (95 mg/kg) or L-carnitine (500 mg/kg) adopting the same schedule of treatment as in bleomycin-treated group. L-carnitine decreased bleomycin-induced elevations in SOD activity, GSH and GSSG contents, however, it failed to suppress the increase in LPO level. On the other hand, treatment with ICRF-187 returned back all the elevated biochemical parameters induced by bleomycin to nearly normal levels. In conclusion, the results of this study showed a potential capability of ICRF-187 to mitigate the bleomycin-induced lung injury. Moreover, despite the inability of L-carnitine to change the elevated LPO content, it was able however, to decrease the elevated endogenous antioxidant parameters. (author)

The interfacial orientation relationship of oxide nanoparticles in a hafnium-containing oxide dispersion-strengthened austenitic stainless steel

Energy Technology Data Exchange (ETDEWEB)

Miao, Yinbin, E-mail: miao2@illinois.edu [Department of Nuclear, Plasma and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Mo, Kun [Nuclear Engineering Division, Argonne National Laboratory, Lemont, IL 60493 (United States); Cui, Bai [Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Department of Material Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Chen, Wei-Ying [Department of Nuclear, Plasma and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Miller, Michael K.; Powers, Kathy A. [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37830 (United States); McCreary, Virginia; Gross, David [Department of Material Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Almer, Jonathan [X-ray Science Division, Argonne National Laboratory, Lemont, IL 60493 (United States); Robertson, Ian M. [Department of Material Science and Engineering, University of Wisconsin-Madison, Madison, WA 53706 (United States); Department of Material Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Stubbins, James F. [Department of Nuclear, Plasma and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)

2015-03-15

This work reports comprehensive investigations on the orientation relationship of the oxide nanoparticles in a hafnium-containing austenitic oxide dispersion-strengthened 316 stainless steel. The phases of the oxide nanoparticles were determined by a combination of scanning transmission electron microscopy–electron dispersive X-ray spectroscopy, atom probe tomography and synchrotron X-ray diffraction to be complex Y–Ti–Hf–O compounds with similar crystal structures, including bixbyite Y{sub 2}O{sub 3}, fluorite Y{sub 2}O{sub 3}–HfO{sub 2} solid solution and pyrochlore (or fluorite) Y{sub 2}(Ti,Hf){sub 2−x}O{sub 7−x}. High resolution transmission electron microscopy was used to characterize the particle–matrix interfaces. Two different coherency relationships along with one axis-parallel relation between the oxide nanoparticles and the steel matrix were found. The size of the nanoparticles significantly influences the orientation relationship. The results provide insight into the relationship of these nanoparticles with the matrix, which has implications for interpreting material properties as well as responses to radiation. - Highlights: • The oxide nanoparticles in a hafnium-containing austenitic ODS were characterized. • The nanoparticles are Y–Hf–Ti–O enriched phases according to APT and STEM–EDS. • Two coherency and an axis-parallel orientation relationships were found by HR-TEM. • Particle size has a prominent effect on the orientation relationship (OR). • Formation mechanism of the oxide nanoparticles was discussed based on the ORs.

Correlation between IL-10 and microRNA-187 expression in epileptic rat hippocampus and patients with temporal lobe epilepsy

Directory of Open Access Journals (Sweden)

Walid A. Alsharafi

2015-12-01

Full Text Available Accumulating evidence is emerging that microRNAs (miRs are key regulators controlling neuroinflammatory processes, which are known to play a potential role in the pathogenesis of temporal lobe epilepsy (TLE. The aim of the present study was to investigate the dynamic expression pattern of interleukin (IL–10 as an anti-inflammatory cytokine and miR-187 and post-transcriptional inflammation-related miRNA in the hippocampus of a rat model of status epilepticus (SE and patients with TLE. We performed a real-time quantitative PCR and western blot on rat hippocampus (2 hours, 7 days, 21 days and 60 days following pilocarpine-induced SE, and on hippocampus obtained from TLE patients and normal controls. To detect the relationship between IL-10 and miR-187 on neurons, lipopolysaccharide (LPS and IL-10-stimulated neurons were prepared. Furthermore, we identified the effect of antagonizing of miR-187 by its antagomir on IL-10 secretion. Here we reported that that IL-10 secretion and miR-187 expression levels are inversely correlated after SE.. In patients with TLE, the expression levels of IL-10 was also significantly upregulated, whereas miR-187 expression was significantly downregulated. Moreover, miR-187 expression was significantly reduced following IL-10 stimulation in an IL-10–dependent manner. On the other hand, antagonizing miR-187 reduced the production of IL-10 in hippocampal tissues of rat model of SE. Our findings demonstrate a critical role of miR-187 in the physiological regulation of IL-10 anti-inflammatory responses and elucidate the role of neuro-inflammation in the pathogenesis of TLE. Therefore, modulation of the IL-10 / miR-187 axis may be a new therapeutic approach for TLE.

Ethylene induced plant stress tolerance by Enterobacter sp. SA187 is mediated by 2-keto-4-methylthiobutyric acid production.

Directory of Open Access Journals (Sweden)

Axel de Zélicourt

2018-03-01

Full Text Available Several plant species require microbial associations for survival under different biotic and abiotic stresses. In this study, we show that Enterobacter sp. SA187, a desert plant endophytic bacterium, enhances yield of the crop plant alfalfa under field conditions as well as growth of the model plant Arabidopsis thaliana in vitro, revealing a high potential of SA187 as a biological solution for improving crop production. Studying the SA187 interaction with Arabidopsis, we uncovered a number of mechanisms related to the beneficial association of SA187 with plants. SA187 colonizes both the surface and inner tissues of Arabidopsis roots and shoots. SA187 induces salt stress tolerance by production of bacterial 2-keto-4-methylthiobutyric acid (KMBA, known to be converted into ethylene. By transcriptomic, genetic and pharmacological analyses, we show that the ethylene signaling pathway, but not plant ethylene production, is required for KMBA-induced plant salt stress tolerance. These results reveal a novel molecular communication process during the beneficial microbe-induced plant stress tolerance.

Simultaneous determination of 56 Mn and 187W in neutron activated steels

International Nuclear Information System (INIS)

Melo, M.C. de

1982-01-01

The simultaneous determination of the count rates due to 56 Mn and 187 W in the activation analysis of steel samples was carried out through exponential regression using least square fitting. The regression coefficients obtained corresponded to the initial count rates of 56 Mn and 187 W. Later on, the count rates of 56 Mn were correlated to the manganese content in the samples and to the count rates of the same radionuclide, obtained in a region of the gamma spectrum where only 56 Mn was apparent. The correlation coefficients were respectively .968 and .99997, thus demonstrating the applicability of the methodology adopted herein. (Author) [pt

Hafnium oxide nanoparticles: toward an in vitro predictive biological effect?

International Nuclear Information System (INIS)

Marill, Julie; Anesary, Naeemunnisa Mohamed; Zhang, Ping; Vivet, Sonia; Borghi, Elsa; Levy, Laurent; Pottier, Agnes

2014-01-01

Hafnium oxide, NBTXR3 nanoparticles were designed for high dose energy deposition within cancer cells when exposed to ionizing radiation. The purpose of this study was to assess the possibility of predicting in vitro the biological effect of NBTXR3 nanoparticles when exposed to ionizing radiation. Cellular uptake of NBTXR3 nanoparticles was assessed in a panel of human cancer cell lines (radioresistant and radiosensitive) by transmission electron microscopy. The radioenhancement of NBTXR3 nanoparticles was measured by the clonogenic survival assay. NBTXR3 nanoparticles were taken up by cells in a concentration dependent manner, forming clusters in the cytoplasm. Differential nanoparticle uptake was observed between epithelial and mesenchymal or glioblastoma cell lines. The dose enhancement factor increased with increase NBTXR3 nanoparticle concentration and radiation dose. Beyond a minimum number of clusters per cell, the radioenhancement of NBTXR3 nanoparticles could be estimated from the radiation dose delivered and the radiosensitivity of the cancer cell lines. Our preliminary results suggest a predictable in vitro biological effect of NBTXR3 nanoparticles exposed to ionizing radiation

Nano-scale Radiotherapy-NBTXR3 Hafnium Oxide Nanoparticles as Promising Cancer Therapy

International Nuclear Information System (INIS)

Maggiorella, L.; Barouch, G.; Devaux, C.; Pottier, A.; Levy, L.; Deutsch, E.; Bourhis, J.; Borghi, E.

2011-01-01

Complete text of publication follows: Background: There is considerable interest in approaches that could improve the therapeutic window of radiotherapy, which represents a crucial modality of treatment in oncology. We present the rationale for designing NBTXR3 nanoparticles activated by radiotherapy and validate the concept. We performed the Monte Carlo calculations for the first time based on the 'local model' simulation that showed a dose enhancement of radiation to tumour cells of approximately nine-fold. NBTXR3 was shown to deposit high energy when the ionizing radiation source is 'on' and to have chemically inert behavior in cellular and subcellular systems demonstrated by very good systemic tolerance, thus decreasing potential health hazards. Material and Methods: We used conventional methods, implemented in different ways, to explore interactions of high Z matter and ionizing radiation with biological systems. In addition, microtomography was performed to explore the nanoparticle volume occupancy inside the tumour and its persistence overtime in mouse tumour models. The antitumour activity of NBTXR3 and tolerance were evaluated in Ewing tumour (A673) and fibrosarcoma (HT1080) using high energy source. Results and Conclusion: We created and developed NBTXR3 nanoparticles with a crystalline hafnium oxide core which provide high electron density structure and inert behavior in biological media. NBTXR3 nanoparticles' characteristics, size, charge and shape, allow for efficient interaction with biological entities, cell membrane binding and cellular uptake. The nanoparticles were shown to form clusters at the subcellular level in tumour models. Of most importance, we show NBTXR3 intra-tumour bioavailability with dispersion of nanoparticles in the three dimensions and persistence within the tumour structure, supporting the use of NBTXR3 as effective antitumour therapeutic agent. Antitumour activity of NBTXR3 showed marked advantage in terms of survival, tumour

A fast response hafnium selective polymeric membrane electrode based on N,N'-bis({alpha}-methyl-salicylidene)-dipropylenetriamine as a neutral carrier

Energy Technology Data Exchange (ETDEWEB)

Rezaei, B. [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)], E-mail: rezaei@cc.iut.ac.ir; Meghdadi, S.; Zarandi, R. Fazel [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

2008-08-30

In this study a new hafnium selective sensor was fabricated from polyvinylchloride (PVC) matrix membrane containing neutral carrier N,N'-bis({alpha}-methyl-salicylidene)-dipropylenetriamine (Mesaldpt) as a new ionophore, sodium tetraphenyl borate (NaTPB) as anionic discriminator and dioctyl phthalate (DOP) as plasticizing solvent mediator in tetrahydrofuran solvent. The electrode exhibits Nernstian response for Hf{sup 4+} (Hafnium(IV)) over a wide concentration range (2.0 x 10{sup -7} to 1.0 x 10{sup -1} M) with the determination coefficient of 0.9966 and slope of 15.1 {+-} 0.1 mV decades{sup -1}. The limit of detection is 1.9 x 10{sup -7} M. The electrode has a fast response time of 18 s and a working pH range of 4-8. The proposed membrane shows excellent discriminating ability towards Hf{sup 4+} ion with regard to several alkali, alkaline earth transition and heavy metal ions. It can be used over a period of 1.5 months with good reproducibility. It is successfully applied for direct determination of Hf{sup 4+} in solutions by standard addition method for real sample analysis.

Ethylene induced plant stress tolerance by Enterobacter sp. SA187 is mediated by 2‐keto‐4‐methylthiobutyric acid production

KAUST Repository

Zé licourt, Axel de; Synek, Lukas; Saad, Maged; Alzubaidy, Hanin S.; Jalal, Rewaa Sauod Mohammed; Xie, Yakun; Andres-Barrao, Cristina; Rolli, Eleonora; Guerard, Florence; Mariappan, Kiruthiga; Daur, Ihsanullah; Colcombet, Jean; Benhamed, Moussa; Depaepe, Thomas; Van Der Straeten, Dominique; Hirt, Heribert

2018-01-01

of mechanisms related to the beneficial association of SA187 with plants. SA187 colonizes both the surface and inner tissues of Arabidopsis roots and shoots. SA187 induces salt stress tolerance by production of bacterial 2-keto-4-methylthiobutyric acid (KMBA

Hafnium-doped hydroxyapatite nanoparticles with ionizing radiation for lung cancer treatment.

Science.gov (United States)

Chen, Min-Hua; Hanagata, Nobutaka; Ikoma, Toshiyuki; Huang, Jian-Yuan; Li, Keng-Yuan; Lin, Chun-Pin; Lin, Feng-Huei

2016-06-01

Recently, photodynamic therapy (PDT) is one of the new clinical options by generating cytotoxic reactive oxygen species (ROS) to kill cancer cells. However, the optical approach of PDT is limited by tissue penetration depth of visible light. In this study, we propose that a ROS-enhanced nanoparticle, hafnium-doped hydroxyapatite (Hf:HAp), which is a material to yield large quantities of ROS inside the cells when the nanoparticles are bombarded with high penetrating power of ionizing radiation. Hf:HAp nanoparticles are generated by wet chemical precipitation with total doping concentration of 15mol% Hf(4+) relative to Ca(2+) in HAp host material. The results show that the HAp particles could be successfully doped with Hf ions, resulted in the formation of nano-sized rod-like shape and with pH-dependent solubility. The impact of ionizing radiation on Hf:HAp nanoparticles is assessed by using in-vitro and in-vivo model using A549 cell line. The 2',7'-dichlorofluorescein diacetate (DCFH-DA) results reveal that after being exposed to gamma rays, Hf:HAp could significantly lead to the formation of ROS in cells. Both cell viability (WST-1) and cytotoxicity (LDH) assay show the consistent results that A549 lung cancer cell lines are damaged with changes in the cells' ROS level. The in-vivo studies further demonstrate that the tumor growth is inhibited owing to the cells apoptosis when Hf:HAp nanoparticles are bombarded with ionizing radiation. This finding offer a new therapeutic method of interacting with ionizing radiation and demonstrate the potential of Hf:HAp nanoparticles in tumor treatment, such as being used in a palliative treatment after lung surgical procedure. Photodynamic therapy (PDT) is one of the new clinical options by generating cytotoxic reactive oxygen species (ROS) to kill cancer cells. Unfortunately, the approach of PDT is usually limited to the treatment of systemic disease and deeper tumor, due to the limited tissue penetration depth of visible

30 CFR 250.187 - What are MMS' incident reporting requirements?

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 2 2010-07-01 2010-07-01 false What are MMS' incident reporting requirements... Reporting Requirements § 250.187 What are MMS' incident reporting requirements? (a) You must report all... other permit issued by MMS, and that are related to operations resulting from the exercise of your...

Sub-10 nm low current resistive switching behavior in hafnium oxide stack

Energy Technology Data Exchange (ETDEWEB)

Hou, Y., E-mail: houyi@pku.edu.cn, E-mail: lfliu@pku.edu.cn [Institute of Microelectronics, Peking University, 100871 Beijing (China); IMEC, Kapeldreef 75, B-3001 Heverlee (Belgium); Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, B-3001 Heverlee (Belgium); Celano, U.; Xu, Z.; Vandervorst, W. [IMEC, Kapeldreef 75, B-3001 Heverlee (Belgium); Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, B-3001 Heverlee (Belgium); Goux, L.; Fantini, A.; Degraeve, R.; Youssef, A.; Jurczak, M. [IMEC, Kapeldreef 75, B-3001 Heverlee (Belgium); Liu, L., E-mail: houyi@pku.edu.cn, E-mail: lfliu@pku.edu.cn; Cheng, Y.; Kang, J. [Institute of Microelectronics, Peking University, 100871 Beijing (China)

2016-03-21

In this letter, a tip-induced cell relying on the conductive atomic force microscope is proposed. It is verified as a referable replica of an integrated resistive random access memory (RRAM) device. On the basis of this cell, the functionality of sub-10 nm resistive switching is confirmed in hafnium oxide stack. Moreover, the low current switching behavior in the sub-10 nm dimension is found to be more pronounced than that of a 50 × 50 nm{sup 2} device. It shows better ON/OFF ratio and low leakage current. The enhanced memory performance is ascribed to a change in the shape of the conductive filament as the device dimensions are reduced to sub-10 nm. Therefore, device downscaling provides a promising approach for the resistance optimization that benefits the RRAM array design.

Biodegradable PLGA85/15 nanoparticles as a delivery vehicle for Chlamydia trachomatis recombinant MOMP-187 peptide

International Nuclear Information System (INIS)

Taha, Murtada A; Singh, Shree R; Dennis, Vida A

2012-01-01

Development of a Chlamydia trachomatis vaccine has been a formidable task partly because of an ineffective delivery system. Our laboratory has generated a recombinant peptide of C. trachomatis major outer membrane protein (MOMP) (rMOMP-187) and demonstrated that it induced at 20 μg ml −1 maximal interleukin (IL)-6 and IL-12p40 Th1 cytokines in mouse J774 macrophages. In a continuous pursuit of a C. trachomatis effective vaccine-delivery system, we encapsulated rMOMP-187 in poly(d,l-lactic-co-glycolic acid) (PLGA, 85:15 PLA/PGA ratio) to serve as a nanovaccine candidate. Physiochemical characterizations were assessed by Fourier transform-infrared spectroscopy, atomic force microscopy, Zetasizer, Zeta potential, transmission electron microcopy and differential scanning calorimetry. The encapsulated rMOMP-187 was small (∼200 nm) with an apparently smooth uniform oval structure, thermally stable (54 °C), negatively charged ( − 27.00 mV) and exhibited minimal toxicity at concentrations −1 to eukaryotic cells (>95% viable cells) over a 24–72 h period. We achieved a high encapsulation efficiency of rMOMP-187 (∼98%) in PLGA, a loading peptide capacity of 2.7% and a slow release of the encapsulated peptide. Stimulation of J774 macrophages with a concentration as low as 1 μg ml −1 of encapsulated rMOMP-187 evoked high production levels of the Th1 cytokines IL-6 (874 pg ml −1 ) and IL-12p40 (674 pg ml −1 ) as well as nitric oxide (8 μM) at 24 h post-stimulation, and in a dose-response and time-kinetics manner. Our data indicate the successful encapsulation and characterization of rMOMP-187 in PLGA and, more importantly, that PLGA enhanced the capacity of the peptide to induce Th1 cytokines and NO in vitro. These findings make this nanovaccine an attractive candidate in pursuit of an efficacious vaccine against C. trachomatis. (paper)

Ethylene induced plant stress tolerance by Enterobacter sp. SA187 is mediated by 2‐keto‐4‐methylthiobutyric acid production

KAUST Repository

Zélicourt, Axel de

2018-03-19

Several plant species require microbial associations for survival under different biotic and abiotic stresses. In this study, we show that Enterobacter sp. SA187, a desert plant endophytic bacterium, enhances yield of the crop plant alfalfa under field conditions as well as growth of the model plant Arabidopsis thaliana in vitro, revealing a high potential of SA187 as a biological solution for improving crop production. Studying the SA187 interaction with Arabidopsis, we uncovered a number of mechanisms related to the beneficial association of SA187 with plants. SA187 colonizes both the surface and inner tissues of Arabidopsis roots and shoots. SA187 induces salt stress tolerance by production of bacterial 2-keto-4-methylthiobutyric acid (KMBA), known to be converted into ethylene. By transcriptomic, genetic and pharmacological analyses, we show that the ethylene signaling pathway, but not plant ethylene production, is required for KMBA-induced plant salt stress tolerance. These results reveal a novel molecular communication process during the beneficial microbe-induced plant stress tolerance.

Ethylene induced plant stress tolerance by Enterobacter sp. SA187 is mediated by 2‐keto‐4‐methylthiobutyric acid production

Science.gov (United States)

Xie, Yakun; Rolli, Eleonora; Guerard, Florence; Colcombet, Jean; Benhamed, Moussa; Depaepe, Thomas

2018-01-01

Several plant species require microbial associations for survival under different biotic and abiotic stresses. In this study, we show that Enterobacter sp. SA187, a desert plant endophytic bacterium, enhances yield of the crop plant alfalfa under field conditions as well as growth of the model plant Arabidopsis thaliana in vitro, revealing a high potential of SA187 as a biological solution for improving crop production. Studying the SA187 interaction with Arabidopsis, we uncovered a number of mechanisms related to the beneficial association of SA187 with plants. SA187 colonizes both the surface and inner tissues of Arabidopsis roots and shoots. SA187 induces salt stress tolerance by production of bacterial 2-keto-4-methylthiobutyric acid (KMBA), known to be converted into ethylene. By transcriptomic, genetic and pharmacological analyses, we show that the ethylene signaling pathway, but not plant ethylene production, is required for KMBA-induced plant salt stress tolerance. These results reveal a novel molecular communication process during the beneficial microbe-induced plant stress tolerance. PMID:29554117

Separation of hafnium from zirconium in their tetrachloride solution in molten alkali metal chlorides

Energy Technology Data Exchange (ETDEWEB)

Salyulev, A B; Kudyakov, V Ya; Smirnov, M V; Moskalenko, N I [AN SSSR, Sverdlovsk. Inst. Ehlektrokhimii

1984-08-01

The coefficient of HfCl/sub 4/ and ZrCl/sub 4/ separation in the process of vapour sublimation from their solutions in molten NaCl, KCl, CsCl, NaCl-KCl and NaCl-CsCl equimolar mixtures is found to vary in the series from approximately 1.10 to approximately 1.22 and practically not to depend on the temperature (in the 600-910 deg) range and concentration (2-25 mol.% ZrCl/sub 4/+HfCl/sub 4/). HfCl/sub 4/ and ZrCl/sub 4/ are shown to form almost perfect solutions with each other, which in their turn form imperfect solutions with molten alkali metal chlorides, with the strength of hafnium complex chloride anions increasing higher than that of zirconium in the series from NaCl to CsCl.

Separation of hafnium from zirconium in their tetrachloride solution in molten alkali metal chlorides

International Nuclear Information System (INIS)

Salyulev, A.B.; Kudyakov, V.Ya.; Smirnov, M.V.; Moskalenko, N.I.

1984-01-01

The coefficient of HfCl 4 and ZrCl 4 separation in the process of vapour sublimation from their solutions in molten NaCl, KCl, CsCl, NaCl-KCl and NaCl-CsCl equimolar mixtures is found to vary in the series from approximately 1.10 to approximately 1.22 and practically not to depend on the temperature (in the 600-910 deg) range and concentration (2-25 mol.% ZrCl 4 +HfCl 4 ). HfCl 4 and ZrCl 4 are shown to form almost perfect solutions with each other, which in their turn form imperfect solutions with molten alkali metal chlorides, with the strength of hafnium complex chloride anions increasing higher than that of zirconium in the series from NaCl to CsCl

Determination of (187)Os in molybdenite by ICP-MS with neutron-induced (186)Os and (188)Os spikes.

Science.gov (United States)

Qu, W; Du, A; Zhao, D

2001-10-31

The article describes a method for the determination of (187)Os in molybdenite by isotope dilution inductively coupled plasma-mass spectrometry (ID-ICP-MS) with neutron-induced (186)Os and (188)Os spike. The spike used in the present work was prepared in line with the principle by which artificial nuclides are produced in a nuclear reaction. The concentration and isotopic composition of osmium in the prepared spike were evaluated accurately with the isotope dilution method, using negative thermal ion mass spectrometry (N-TIMS). The advantage of this method is that using (186)Os and (188)Os double spikes can effectively compensate for the mass discrimination effects of ICP-MS. Thus, the common correction practice for mass bias in the isotope dilution method with a single spike is unnecessary. In addition, the method enables one to reduce the determined error arising from instrumental instability. The precision for the (187)Os/((186)Os+(188)Os) ratio was approximately 2% (2sigma, RSD), but in the case of (187)Os/(186)Os, (187)Os/(188)Os and (186)Os/(188)Os, precision ranged from 2.0 to 8% (2sigma, RSD). The results for (187)Os concentration in a molybdenite sample determined with this method showed good agreement with reference values.

Draft genome sequence of Enterobacter sp. Sa187, an endophytic bacterium isolated from the desert plant Indigofera argentea

NARCIS (Netherlands)

Lafi, Feras F.; Alam, Intikhab; Geurts, Rene; Bisseling, Ton; Bajic, Vladimir B.; Hirt, Heribert; Saad, Maged M.

2017-01-01

Enterobacter sp. Sa187 is a plant endophytic bacterium, isolated from root nodules of the desert plant Indigofera argentea, collected from the Jizan region of Saudi Arabia. Here, we report the genome sequence of Sa187, highlighting several genes involved in plant growth-promoting activity and

Draft Genome Sequence of Enterobacter sp. Sa187, an Endophytic Bacterium Isolated from the Desert Plant Indigofera argentea

KAUST Repository

Lafi, Feras Fawzi; Alam, Intikhab; Geurts, Rene; Bisseling, Ton; Bajic, Vladimir B.; Hirt, Heribert; Saad, Maged

2017-01-01

Enterobacter sp. Sa187 is a plant endophytic bacterium, isolated from root nodules of the desert plant Indigofera argentea, collected from the Jizan region of Saudi Arabia. Here, we report the genome sequence of Sa187, highlighting several genes involved in plant growth–promoting activity and environmental adaption.

Draft Genome Sequence of Enterobacter sp. Sa187, an Endophytic Bacterium Isolated from the Desert Plant Indigofera argentea

KAUST Repository

Lafi, Feras Fawzi

2017-02-17

Enterobacter sp. Sa187 is a plant endophytic bacterium, isolated from root nodules of the desert plant Indigofera argentea, collected from the Jizan region of Saudi Arabia. Here, we report the genome sequence of Sa187, highlighting several genes involved in plant growth–promoting activity and environmental adaption.

Theoretical study on rotational bands and shape coexistence of 183,185,187Tl in the particle-triaxial-rotor model

International Nuclear Information System (INIS)

Chen Guojie; Cao Hui; Liu Yuxin; Song Huichao

2006-01-01

By taking the particle-triaxial-rotor model with variable moment of inertia, we systematically investigate the energy spectra, deformations, and single-particle configurations of the nuclei 183,185,187 Tl. The calculated energy spectra agree quite well with experimental data. The obtained results indicate that the rotation-aligned bands observed in 183,185,187 Tl originate from one of the [530](1/2) - ,[532](3/2) - ,[660](1/2) + proton configurations coupled to a prolate deformed core. Furthermore, the negative parity bands built upon the (9/2) - isomeric states in 183,185,187 Tl are formed by a proton with the [505](9/2) - configuration coupled to a core with triaxial oblate deformation, and the positive parity band on the (13/2) + isomeric state in 187 Tl is generated by a proton with configuration [606](13/2) + coupled to a triaxial oblate core

Density and surface tension of melts of zirconium and hafnium fluorides with lithium fluoride

International Nuclear Information System (INIS)

Katyshev, S.F.; Artemov, V.V.; Desyatnik, V.N.

1988-01-01

A study was conducted to determine the temperature dependence of the density and surface tension of melts of LiF-ZrF 4 and LiF-HfF 4 . Density and surface tension were determined by the method of maximum pressure in an argon bubble. On the basis of experimental data over the entire concentration range the molar volumes and their relative deviations from the additive molar volumes were calculated for 1100 0 K. The positive deviations of the molar volumes from additivity in the LiF-HfF 4 system (22.45%) were greater than in the LiF-ZrF 4 system (15.75%). This indicated that the reaction with lithium fluoride is intensified with the switch to the hafnium fluoride. Results also demonstrated that the fluorides are surface-active components in the molten mixtures

Spectrum and static moments of /sup 187/Re

Energy Technology Data Exchange (ETDEWEB)

Mittal, R; Sharma, S D; Sahota, H S; Sehgal, V K [Punjabi Univ., Patiala (India). Dept. of Physics

1979-01-01

The spectrum and static moments of /sup 187/Re are calculated using extension of Davydov-Filippov model. The Hamiltonian including the coriolis coupling term is used to calculate the effective moment of inertia for various bands. The kinking effect in the excited bands is studied by mixing the pair of bands such that both bands in single pair have same k value either k = 1/2 or 3/2. The effective moment of inertia under excitation is found to change with spin. The change is found in agreement with the theoretical prediction on the basis of this model.

MicroRNA-187, down-regulated in clear cell renal cell carcinoma and associated with lower survival, inhibits cell growth and migration though targeting B7-H3

Energy Technology Data Exchange (ETDEWEB)

Zhao, Jun [Foshan Maternal and Child Health Care Hospital, Foshan (China); Lei, Ting [Zhongshan People’s Hospital, Zhongshan (China); Xu, Congjie [Department of Urology, Pepole’s Hospital of Hainan Province, Haikou (China); Li, Huan; Ma, Wenmin; Yang, Yunxia; Fan, Shuming [Foshan Maternal and Child Health Care Hospital, Foshan (China); Liu, Yuchen, E-mail: s_ycliu1@stu.edu.cn [Anhui Medical University, Hefei (China)

2013-08-23

Highlights: •miR-187 is down-regulated in clear cell renal cell carcinoma (ccRCC). •Down-regulation of miR-187 is associated with poor outcomes in patients with ccRCC. •miR-187 inhibits cell growth and migration though targeting B7-H3 in ccRCC. -- Abstract: Aberrantly expressed microRNAs (miRNAs) are frequently associated with the aggressive malignant behavior of human cancers, including clear cell renal cell carcinoma (ccRCC). Based on the preliminary deep sequencing data, we hypothesized that miR-187 may play an important role in ccRCC development. In this study, we found that miR-187 was down-regulated in both tumor tissue and plasma of ccRCC patients. Lower miR-187 expression levels were associated with higher tumor grade and stage. All patients with high miR-187 expression survived 5 years, while with low miR-187 expression, only 42% survived. Suppressed in vitro proliferation, inhibited in vivo tumor growth, and decreased motility were observed in cells treated with the miR-187 expression vector. Further studies showed that B7 homolog 3 (B7-H3) is a direct target of miR-187. Over-expression of miR-187 decreased B7-H3 mRNA level and repressed B7-H3-3′-UTR reporter activity. Knockdown of B7-H3 using siRNA resulted in similar phenotype changes as that observed for overexpression of miR-187. Our data suggest that miR-187 is emerging as a novel player in the disease state of ccRCC. miR-187 plays a tumor suppressor role in ccRCC.

MicroRNA-187, down-regulated in clear cell renal cell carcinoma and associated with lower survival, inhibits cell growth and migration though targeting B7-H3

International Nuclear Information System (INIS)

Zhao, Jun; Lei, Ting; Xu, Congjie; Li, Huan; Ma, Wenmin; Yang, Yunxia; Fan, Shuming; Liu, Yuchen

2013-01-01

Highlights: •miR-187 is down-regulated in clear cell renal cell carcinoma (ccRCC). •Down-regulation of miR-187 is associated with poor outcomes in patients with ccRCC. •miR-187 inhibits cell growth and migration though targeting B7-H3 in ccRCC. -- Abstract: Aberrantly expressed microRNAs (miRNAs) are frequently associated with the aggressive malignant behavior of human cancers, including clear cell renal cell carcinoma (ccRCC). Based on the preliminary deep sequencing data, we hypothesized that miR-187 may play an important role in ccRCC development. In this study, we found that miR-187 was down-regulated in both tumor tissue and plasma of ccRCC patients. Lower miR-187 expression levels were associated with higher tumor grade and stage. All patients with high miR-187 expression survived 5 years, while with low miR-187 expression, only 42% survived. Suppressed in vitro proliferation, inhibited in vivo tumor growth, and decreased motility were observed in cells treated with the miR-187 expression vector. Further studies showed that B7 homolog 3 (B7-H3) is a direct target of miR-187. Over-expression of miR-187 decreased B7-H3 mRNA level and repressed B7-H3-3′-UTR reporter activity. Knockdown of B7-H3 using siRNA resulted in similar phenotype changes as that observed for overexpression of miR-187. Our data suggest that miR-187 is emerging as a novel player in the disease state of ccRCC. miR-187 plays a tumor suppressor role in ccRCC

MicroRNA profiling in the dentate gyrus in epileptic rats: The role of miR-187-3p.

Science.gov (United States)

Zhang, Suya; Kou, Yubin; Hu, Chunmei; Han, Yan

2017-06-01

This study aimed to explore the role of aberrant miRNA expression in epilepsy and to identify more potential genes associated with epileptogenesis.The miRNA expression profile of GSE49850, which included 20 samples from the rat epileptic dentate gyrus at 7, 14, 30, and 90 days after electrical stimulation and 20 additional samples from sham time-matched controls, was downloaded from the Gene Expression Omnibus database. The significantly differentially expressed miRNAs were identified in stimulated samples at each time point compared to time-matched controls, respectively. The target genes of consistently differentially expressed miRNAs were screened from miRDB and microRNA.org databases, followed by Gene Ontology (GO) and pathway enrichment analysis and regulatory network construction. The overlapping target genes for consistently differentially expressed miRNAs were also identified from these 2 databases. Furthermore, the potential binding sites of miRNAs and their target genes were analyzed.Rno-miR-187-3p was consistently downregulated in stimulated groups compared with time-matched controls. The predicted target genes of rno-miR-187-3p were enriched in different GO terms and pathways. In addition, 7 overlapping target genes of rno-miR-187-3p were identified, including NFS1, PAQR4, CAND1, DCLK1, PRKAR2A, AKAP3, and KCNK10. These 7 overlapping target genes were determined to have a different number of matched binding sites with rno-miR-187-3p.Our study suggests that miR-187-3p may play an important role in epilepsy development and progression via regulating numerous target genes, such as NFS1, CAND1, DCLK1, AKAP3, and KCNK10. Determining the underlying mechanism of the role of miR-187-3p in epilepsy may make it a potential therapeutic option.

Tribo-electrochemical characterization of hafnium multilayer systems deposited on nitride/vanadium nitride AISI 4140 steel

Science.gov (United States)

Mora, M.; Vera, E.; Aperador, W.

2016-02-01

In this work is presented the synergistic behaviour among corrosion/wear (tribocorrosion) of the multilayer coatings hafnium nitride/vanadium nitride [HfN/VN]n. The multilayers were deposited on AISI 4140 steel using the technique of physical vapor deposition PVD magnetron sputtering, the tests were performed using a pin-on-disk tribometer, which has an adapted potentiostat galvanostat with three-electrode electrochemical cell. Tribocorrosive parameters such as: Friction coefficient between the coating and the counter body (100 Cr6 steel ball); Polarization resistance by means of electrochemical impedance spectroscopy technique and corrosion rate by polarization curves were determined. It was observed an increase in the polarization resistance, a decrease in the corrosion rate and a low coefficient of friction in comparison with the substrate, due to an increase on the number of bilayers.

Tribo-electrochemical characterization of hafnium multilayer systems deposited on nitride/vanadium nitride AISI 4140 steel

International Nuclear Information System (INIS)

Mora, M; Vera, E; Aperador, W

2016-01-01

In this work is presented the synergistic behaviour among corrosion/wear (tribocorrosion) of the multilayer coatings hafnium nitride/vanadium nitride [HfN/VN]n. The multilayers were deposited on AISI 4140 steel using the technique of physical vapor deposition PVD magnetron sputtering, the tests were performed using a pin-on-disk tribometer, which has an adapted potentiostat galvanostat with three-electrode electrochemical cell. Tribocorrosive parameters such as: Friction coefficient between the coating and the counter body (100 Cr6 steel ball); Polarization resistance by means of electrochemical impedance spectroscopy technique and corrosion rate by polarization curves were determined. It was observed an increase in the polarization resistance, a decrease in the corrosion rate and a low coefficient of friction in comparison with the substrate, due to an increase on the number of bilayers. (paper)

Rapid screening of nuclear grade zirconium silicate without separation of hafnium from the bulk matrix

International Nuclear Information System (INIS)

Venkatesh, Manisha; Sharma, P.K.; Avhad, D.K.; Basu, H.; Singhal, R.K.; Reddy, A.V.R.

2014-01-01

Zirconium silicate, also zirconium orthosilicate, (ZrSiO 4 ) is a chemical compound, and occurs in nature as zircon, a silicate mineral. The concentration of Hafnium in nuclear grade Zirconium must be less than 0.2% w/w of Zr. In view of this it must be accurately chemically characterized before issuing a certification for export under non nuclear category. As the chemistry of Zr and Hf is similar, it is difficult to separate Hf by direct wet chemical method. During this work, concentration of Hf in zirconium silicate was measured by Field Portable X-ray Fluorescence (FPXRF) and results obtained were validated by using detailed chemical method. FPXRF spectrometry has become a common analytical technique for on-site screening and fast turnaround analysis of contaminant elements in environmental samples

Hafnium Films and Magnetic Shielding for TIME, A mm-Wavelength Spectrometer Array

Science.gov (United States)

Hunacek, J.; Bock, J.; Bradford, C. M.; Butler, V.; Chang, T.-C.; Cheng, Y.-T.; Cooray, A.; Crites, A.; Frez, C.; Hailey-Dunsheath, S.; Hoscheit, B.; Kim, D. W.; Li, C.-T.; Marrone, D.; Moncelsi, L.; Shirokoff, E.; Steinbach, B.; Sun, G.; Trumper, I.; Turner, A.; Uzgil, B.; Weber, A.; Zemcov, M.

2018-04-01

TIME is a mm-wavelength grating spectrometer array that will map fluctuations of the 157.7-μm emission line of singly ionized carbon ([CII]) during the epoch of reionization (redshift z ˜ 5-9). Sixty transition-edge sensor (TES) bolometers populate the output arc of each of the 32 spectrometers, for a total of 1920 detectors. Each bolometer consists of gold absorber on a ˜ 3 × 3 mm silicon nitride micro-mesh suspended near the corners by 1 × 1 × 500 μm silicon nitride legs targeting a photon-noise-dominated NEP ˜ 1 × 10^{-17} W/√{Hz} . Hafnium films are explored as a lower-T_c alternative to Ti (500 mK) for TIME TESs, allowing thicker support legs for improved yield. Hf T_c is shown to vary between 250 and 450 mK when varying the resident Ar pressure during deposition. Magnetic shielding designs and simulations are presented for the TIME first-stage SQUIDs. Total axial field suppression is predicted to be 5 × 10^7.

26 CFR 1.187-1 - Amortization of certain coal mine safety equipment.

Science.gov (United States)

2010-04-01

... 26 Internal Revenue 3 2010-04-01 2010-04-01 false Amortization of certain coal mine safety... (CONTINUED) INCOME TAX (CONTINUED) INCOME TAXES Itemized Deductions for Individuals and Corporations (continued) § 1.187-1 Amortization of certain coal mine safety equipment. (a) Allowance of deduction—(1) In...

A spanish mineral of zirconium and hafnium. Separation of the two elements by liquid-liquid extraction, using tributyl phosphate as chelating agent

International Nuclear Information System (INIS)

Ruiz Sanchez, F.; Cruz Castillo, F. de la; Fernandez Cellini, R.

1962-01-01

The zirconium and Hafnium oxides are obtained from a Spanish mineral of zircon with an average contest of 55% in ZrO 2 -HfO 2 . An alkaline fusion to open the mineral, followed by a purification by crystallization as (Zr O-Hf O)Cl 2 H 2 O or as (Zr-Hf) (SO 4 ) 2 . 4H 2 O, is used. A discussion of the best experimental conditions for opening the mineral and of the purification method is made. (Author) 45 refs

Evidence for Treatable Inborn Errors of Metabolism in a Cohort of 187 Greek Patients with Autism Spectrum Disorder (ASD

Directory of Open Access Journals (Sweden)

Martha eSpilioti

2013-12-01

Full Text Available We screened for the presence of inborn errors of metabolism (IEM in 187 children (105 males; 82 females, ages 4 -14 years old who presented with confirmed features of ASD. Twelve patients (7% manifested increased 3-hydroxyisovaleric acid (3-OH-IVA excretion in urine, and minor to significant improvement in autistic features was observed in seven patients following supplementation with biotin. Five diagnoses included: Lesch Nyhan syndrome (2, succinic semialdehyde dehydrogenase (SSADH deficiency (2 and phenylketonuria (1 (2.7%. Additional metabolic disturbances suggestive of IEMs included two patients whose increased urine 3-OH-IVA was accompanied by elevated methylcitrate and lactate in sera, and 30 patients that showed abnormal glucose-loading tests. In the latter group, 16/30 patients manifested increased sera beta hydroxybutyrate (b-OH-b production and 18/30 had a paradoxical increase of sera lactate. Six patients with elevated b-OH-b in sera showed improved autistic features following implementation of a ketogenic diet. Five patients showed decreased serum ketone body production with glucose loading. Twelve of 187 patients demonstrated nonspecific MRI pathology, while 25/187 had abnormal EEG findings. Finally, family history was positive for 22/187 patients (1st or 2nd degree relative with comparable symptomatology and consanguinity was documented for 12/187 patients. Our data provide evidence for a new biomarker (3-OH-IVA and novel treatment approaches in ASD patients.Concise 1 sentence take-home message: Detailed metabolic screening in a Greek cohort of autismspectrum disorder (ASD patients revealed biomarkers (urine 3-hydroxyisovaleric acid and serum b-OH-b in 7% (13/187 of patients for whom biotin supplementation or institution of a ketogenic diet resulted in mild to significant clinical improvement in autistic features.

A Lesson in Democracy? CUFA, Proposition 187, and the Boycott of California.

Science.gov (United States)

Ross, E. Wayne

1997-01-01

Discusses the boycott of meetings in California by the College and University Faculty Assembly (CUFA) of the National Council for the Social Studies (NCSS) because of the passage of Proposition 187. Uses the decision for the boycott as a means to explore the notions of democracy, citizenship, and citizenship education. (CMK)

Chimeric Ply187 endolysin kills Staphylococcus aureus more effectively than the parental enzyme.

Science.gov (United States)

Peptidoglycan hydrolases are an effective new source of antimicrobials. A chimeric fusion protein of the Ply187 endopeptidase domain and LysK SH3b cell wall binding domain is a potent agent against Staphylococcus aureus in three functional assays....

Calculation and evaluation of the activation cross sections for 187Re(n,2n)186m,gRe reactions

International Nuclear Information System (INIS)

Huang Xiaolong; Lu Hanlin; Zhou Chunmei

1998-01-01

The activation cross sections for 187 Re(n,2n) 186m,g Re reactions are calculated using UNF code. The calculations are in good agreement with the re-evaluated measured data. Finally the excitation function for 187 Re(n,2n) 186m,g Re reactions are evaluated and recommended based on present calculations and evaluated decay data

George de Hevesy (1885-1966). Discoverer of hafnium, founder of radioanalytical chemistry and X-ray fluorescence analysis and father of nuclear medicine

International Nuclear Information System (INIS)

Niese, Siegfried

2017-01-01

George de Hevesy known as discoverer of hafnium, founder of radioanalytical chemistry and X-ray fluorescence analysis and father of nuclear medicine has done important research work in inorganic, physical and radioanalytical and physiological chemistry as well as in geochemistry, radiation biology and medicine. When he must flee for political reasons from a country he must change his colleagues, his equipments, and the topic of his work. It is extremely surprising that he could receive important results under such circumstances even at an advanced age. (author)

PKCδ-mediated phosphorylation of BAG3 at Ser187 site induces epithelial-mesenchymal transition and enhances invasiveness in thyroid cancer FRO cells.

Science.gov (United States)

Li, N; Du, Z-X; Zong, Z-H; Liu, B-Q; Li, C; Zhang, Q; Wang, H-Q

2013-09-19

Protein kinase C delta (PKCδ) is a serine (Ser)/threonine kinase, which regulates numerous cellular processes, including proliferation, differentiation, migration and apoptosis. In the current study, Chinese hamster ovary cells were transfected with either a constitutively activated PKCδ or a dominant negative PKCδ, phosphoprotein enrichment, two-dimensional difference gel electrophoresis and mass spectrometry was combined to globally identified candidates of PKCδ cascade. We found that Bcl-2 associated athanogene 3 (BAG3) was one of the targets of PKCδ cascade, and BAG3 interacted with PKCδ in vivo. In addition, we clarified that BAG3 was phosphorylate at Ser187 site in a PKCδ-dependent manner in vivo. BAG3 has been implicated in multiple cellular functions, including proliferation, differentiation, apoptosis, migration, invasion, macroautophagy and so on. We generated wild-type (WT)-, Ser187Ala (S187A)- or Ser187Asp (S187D)-BAG3 stably expressing FRO cells, and noticed that phosphorylation state of BAG3 influenced FRO morphology. Finally, for the first time, we showed that BAG3 was implicated in epithelial-mesenchymal transition (EMT) procedure, and phosphorylation state at Ser187 site had a critical role in EMT regulation by BAG3. Collectively, the current study indicates that BAG3 is a novel substrate of PKCδ, and PKCδ-mediated phosphorylation of BAG3 is implicated in EMT and invasiveness of thyroid cancer cells.

Silicon-doped hafnium oxide anti-ferroelectric thin films for energy storage

Science.gov (United States)

Ali, Faizan; Liu, Xiaohua; Zhou, Dayu; Yang, Xirui; Xu, Jin; Schenk, Tony; Müller, Johannes; Schroeder, Uwe; Cao, Fei; Dong, Xianlin

2017-10-01

Motivated by the development of ultracompact electronic devices as miniaturized energy autonomous systems, great research efforts have been expended in recent years to develop various types of nano-structural energy storage components. The electrostatic capacitors characterized by high power density are competitive; however, their implementation in practical devices is limited by the low intrinsic energy storage density (ESD) of linear dielectrics like Al2O3. In this work, a detailed experimental investigation of energy storage properties is presented for 10 nm thick silicon-doped hafnium oxide anti-ferroelectric thin films. Owing to high field induced polarization and slim double hysteresis, an extremely large ESD value of 61.2 J/cm3 is achieved at 4.5 MV/cm with a high efficiency of ˜65%. In addition, the ESD and the efficiency exhibit robust thermal stability in 210-400 K temperature range and an excellent endurance up to 109 times of charge/discharge cycling at a very high electric field of 4.0 MV/cm. The superior energy storage performance together with mature technology of integration into 3-D arrays suggests great promise for this recently discovered anti-ferroelectric material to replace the currently adopted Al2O3 in fabrication of nano-structural supercapacitors.

Tuning the magnetic properties of pure hafnium by high pressure torsion

International Nuclear Information System (INIS)

Cepeda-Jiménez, C.M.; Beltrán, J.I.; Hernando, A.; García, M.A.; Ynduráin, F.; Zhilyaev, A.; Pérez-Prado, M.T.

2017-01-01

This work demonstrates that room temperature (RT) ferromagnetism might be triggered in pure hafnium (Hf), a classic paramagnet, by severe plastic deformation (SPD) via high pressure torsion (HPT). The origin of this phenomenon is elucidated by a combined approach including density functional theory (DFT) calculations and transmission electron microscopy (TEM). In particular, it is shown that the elastic lattice distorsions induced in pure Hf as a consequence of grain refinement down to the nanocrystalline regime by HPT lead to the development of a new monoclinic crystalline structure that exhibits a spontaneous magnetization at RT. DFT calculations are utilized to prove that local stretching of the original pure Hf hexagonal close packed (hcp) lattice along specific pyramidal directions, due to the presence of internal stresses in the deformed nanostructure, may give rise to the emergence of the monoclinic phase, which is endowed with a net magnetic moment. An excellent agreement is found between DFT calculations and experimental TEM observations, which provide a first evidence of the presence of the pure Hf monoclinic crystal lattice. This work shows that SPD may constitute a viable, yet widely unexplored, strategy to tune the magnetic properties and, in particular, to induce RT ferromagnetism in bulk non-magnetic metals.

Characterization of hafnium oxide resistive memory layers deposited on copper by atomic layer deposition

Energy Technology Data Exchange (ETDEWEB)

Briggs, B.D.; Bishop, S.M. [SUNY College of Nanoscale Science and Engineering, 255 Fuller Road, Albany, NY 12203 (United States); Leedy, K.D. [Air Force Research Laboratory, 2241 Avionics Circle, Wright Patterson Air Force Base, Dayton, OH 45433 (United States); Cady, N.C., E-mail: ncady@albany.edu [SUNY College of Nanoscale Science and Engineering, 255 Fuller Road, Albany, NY 12203 (United States)

2014-07-01

Hafnium oxide-based resistive memory devices have been fabricated on copper bottom electrodes. The HfO{sub x} active layers in these devices were deposited by atomic layer deposition (ALD) at 250 °C with tetrakis(dimethylamido)hafnium(IV) as the metal precursor and an O{sub 2} plasma as the reactant. Depth profiles of the HfO{sub x} by X-ray photoelectron spectroscopy and secondary ion mass spectroscopy revealed a copper concentration on the order of five atomic percent throughout the HfO{sub x} film. In addition to the Cu doped HfO{sub x}, a thin layer (20 nm) of Cu{sub x}O is present at the surface. This surface layer is believed to have formed during the ALD process, and greatly complicates the analysis of the switching mechanism. The resistive memory structures fabricated from the ALD HfO{sub x} exhibited non-polar resistive switching, independent of the top metal electrode (Ni, Pt, Al, Au). Resistive switching current voltage (I–V) curves were analyzed using Schottky emission and ionic hopping models to gain insight into the physical mechanisms underpinning the device behavior. During the forming process it was determined that, at voltages in excess of 2.5 V, an ionic hopping model is in good agreement with the I–V data. The extracted ion hopping distance ∼ 4 Å was within the range of interatomic spacing of HfO{sub 2} during the forming process consistent with ionic motion of Cu{sup 2+} ions. Lastly the on state I–V data was dominated at larger voltages by Schottky emission with an estimated barrier height of ∼ 0.5 eV and a refractive index of 2.59. The consequence of the Schottky emission analysis indicates the on state resistance to be a product of a Pt/Cu{sub 2}O/Cu filament(s)/Cu{sub 2}O/Cu structure. - Highlights: • HfO{sub 2} was grown via atomic layer deposition at 250 and 100 °C on Cu substrates. • A Cu{sub 2}O surface layer and Cu doping were observed in post-deposition of HfO{sub 2}. • Resistive memory devices were fabricated and

Thermodynamic and kinetic studies in the systems alkali chloride-zinconium (or hafnium) tetrachloride: Part I. Vapour pressure measurements over hexachloro compounds and use of vapour pressure data in fractional decomposition

International Nuclear Information System (INIS)

Ray, H.S.; Bhat, B.G.; Reddy, G.S.; Biswas, A.K.

1978-01-01

A molten tin isoteniscope has been used to measure the vapour pressures over ZrCl 4 , HfCl 4 and the hexachlore zirconates (M 2 ZrCl 6 ) and the hexachloro hafnates (M 2 HfCl 6 ) of four alkali metals (M = Na,K,Rb,Cs). The method of preparation of these compounds and the effect of small amounts of residual alkali chlorides on the their vapour pressure are discussed. The pressure-temperature plots are examined in the light of some theoretical postulates. A scheme for separation of hafnium from zirconoium by multistage fractional decomposition of the hexachlore compounds of any alkali metal is described. The scheme, which is analogous to rectification in liquid-vapour systems, employs a countercurrent flow of Zr(Hf)Cl 4 in a gas stream and a moving bed of alkali chlorides. The separation is based on the difference in the dissociation equilibrium for zirconium and hafnium compounds. Stage calculations for such a scheme and the main conclusions of a computational work are presented. (author)

Implications of 187Os isotopic heterogeneities in a mantle plume: evidence from Gorgona Island and Curaçao

Science.gov (United States)

Walker, Richard J.; Storey, Michael; Kerr, Andrew C.; Tarney, John; Arndt, Nicholas T.

1999-03-01

Recent work has suggested that the mafic-ultramafic volcanism in evidence throughout portions of the Caribbean, Central America, and northern South America, including the islands of Gorgona and Curaçao, was generated as part of a middle-Cretaceous, large igneous province. New Re-Os isochron results for tholeiitic basalts from Gorgona and Curaçao indicate crystallization ages of 89.2 ± 5.2 and 85.6 ± 8.1 Ma, respectively, consistent with reported Ar ages. The Gorgona ultramafic suite shows a large range in initial Os isotopic composition, with γ Os values ranging from -0.5 to +12.4. This large range reflects isotopic heterogeneities in the mantle source similar to those observed for modern ocean island basalts. In contrast to ocean island basalts, however, Os isotopic compositions do not correlate with variations in Nd, Sr, or Pb isotopic compositions, which are within the range of depleted mid-ocean ridge basalts. The processes that produced these rocks evidently resulted in the decoupling of Os isotopes from the Nd, Sr, and Pb isotopic systems. Picrites from Curaçao have very uniform, chondritic initial Os isotopic compositions, with initial γ Os values ranging only from -0.4 to ±1.4. Basalts from Curaçao, however, define an isochron with a 187Os-enriched initial isotopic composition (γ Os = +9.5). In contrast to the 187Os-enriched ultramafic rocks from Gorgona, the enrichment in these basalts could have resulted from lithospheric contamination. If the Gorgona and Curaçao rocks were derived from the same plume, Os results, combined with Sr, Nd, and Pb data indicate a heterogeneous plume, with multiple compositionally and isotopically distinct domains. The Os isotopic results require derivation of Os from a minimum of two distinct reservoirs, one with a composition very similar to the chondritic average and one with long-term enriched Re/Os. Oceanic crustal recycling has been invoked to explain most of the 187Os enrichments that have been observed in

National Ignition Facility subsystem design requirements final optics assembly subsystem SSDR 1.8.7

International Nuclear Information System (INIS)

Adams, C.

1996-01-01

This SSDR establishes the performance, design, development and test requirements for the Final Optic Assembly (FOA). The FOA (WBS 1.8.7) as part of the Target Experimental System (1.8) includes vacuum windows, frequency conversion crystals, focus lens, debris shields and supporting mechanical equipment

The biological effect of 125I seed continuous low dose rate irradiation in CL187 cells

Directory of Open Access Journals (Sweden)

Zhuang Hong-Qing

2009-01-01

Full Text Available Abstract Background To investigate the effectiveness and mechanism of 125I seed continuous low-dose-rate irradiation on colonic cell line CL187 in vitro. Methods The CL187 cell line was exposed to radiation of 60Coγ ray at high dose rate of 2 Gy/min and 125I seed at low dose rate of 2.77 cGy/h. Radiation responses to different doses and dose rates were evaluated by colony-forming assay. Under 125I seed low dose rate irradiation, a total of 12 culture dishes were randomly divided into 4 groups: Control group, and 2, 5, and 10 Gy irradiation groups. At 48 h after irradiation, apoptosis was detected by Annexin and Propidium iodide (PI staining. Cell cycle arrests were detected by PI staining. In order to investigate the influence of low dose rate irradiation on the MAPK signal transduction, the expression changes of epidermal growth factor receptor (EGFR and Raf under continuous low dose rate irradiation (CLDR and/or EGFR monoclonal antibodies were determined by indirect immunofluorescence. Results The relative biological effect (RBE for 125I seeds compared with 60Co γ ray was 1.41. Apoptosis rates of CL187 cancer cells were 13.74% ± 1.63%, 32.58% ± 3.61%, and 46.27% ± 3.82% after 2 Gy, 5 Gy, and 10 Gy irradiation, respectively; however, the control group apoptosis rate was 1.67% ± 0.19%. G2/M cell cycle arrests of CL187 cancer cells were 42.59% ± 3.21%, 59.84% ± 4.96%, and 34.61% ± 2.79% after 2 Gy, 5 Gy, and 10 Gy irradiation, respectively; however, the control group apoptosis rate was 26.44% ± 2.53%. P 2/M cell cycle arrest. After low dose rate irradiation, EGFR and Raf expression increased, but when EGFR was blocked by a monoclonal antibody, EGFR and Raf expression did not change. Conclusion 125I seeds resulted in more effective inhibition than 60Co γ ray high dose rate irradiation in CL187 cells. Apoptosis following G2/M cell cycle arrest was the main mechanism of cell-killing effects under low dose rate irradiation. CLDR could

Metallorganic chemical vapor deposition and atomic layer deposition approaches for the growth of hafnium-based thin films from dialkylamide precursors for advanced CMOS gate stack applications

Science.gov (United States)

Consiglio, Steven P.

To continue the rapid progress of the semiconductor industry as described by Moore's Law, the feasibility of new material systems for front end of the line (FEOL) process technologies needs to be investigated, since the currently employed polysilicon/SiO2-based transistor system is reaching its fundamental scaling limits. Revolutionary breakthroughs in complementary-metal-oxide-semiconductor (CMOS) technology were recently announced by Intel Corporation and International Business Machines Corporation (IBM), with both organizations revealing significant progress in the implementation of hafnium-based high-k dielectrics along with metal gates. This announcement was heralded by Gordon Moore as "...the biggest change in transistor technology since the introduction of polysilicon gate MOS transistors in the late 1960s." Accordingly, the study described herein focuses on the growth of Hf-based dielectrics and Hf-based metal gates using chemical vapor-based deposition methods, specifically metallorganic chemical vapor deposition (MOCVD) and atomic layer deposition (ALD). A family of Hf source complexes that has received much attention recently due to their desirable properties for implementation in wafer scale manufacturing is the Hf dialkylamide precursors. These precursors are room temperature liquids and possess sufficient volatility and desirable decomposition characteristics for both MOCVD and ALD processing. Another benefit of using these sources is the existence of chemically compatible Si dialkylamide sources as co-precursors for use in Hf silicate growth. The first part of this study investigates properties of MOCVD-deposited HfO2 and HfSixOy using dimethylamido Hf and Si precursor sources using a customized MOCVD reactor. The second part of this study involves a study of wet and dry surface pre-treatments for ALD growth of HfO2 using tetrakis(ethylmethylamido)hafnium in a wafer scale manufacturing environment. The third part of this study is an investigation of

Recoil Induced Room Temperature Stable Frenkel Pairs in a-Hafnium Upon Thermal Neutron Capture

Science.gov (United States)

Butz, Tilman; Das, Satyendra K.; Dey, Chandi C.; Ghoshal, Shamik

2013-11-01

Ultrapure hafnium metal (110 ppm zirconium) was neutron activated with a thermal neutron flux of 6:6 · 1012 cm-2s-1 in order to obtain 181Hf for subsequent time differential perturbed angular correlation (TDPAC) experiments using the nuclear probe 181Hf(β-) 181Ta. Apart from the expected nuclear quadrupole interaction (NQI) signal for a hexagonal close-packed (hcp) metal, three further discrete NQIs were observed with a few percent fraction each. The TDPAC spectra were recorded for up to 11 half lives with extreme statistical accuracy. The fitted parameters vary slightly within the temperature range between 248 K and 373 K. The signals corresponding to the three additional sites completely disappear after `annealing' at 453 K for one minute. Based on the symmetry of the additional NQIs and their temperature dependencies, they are tentatively attributed to Frenkel pairs produced by recoil due to the emission of a prompt 5:694 MeV -ray following thermal neutron capture and reported by the nuclear probe in three different positions. These Frenkel pairs are stable up to at least 373 K.

The energy landscape of glassy dynamics on the amorphous hafnium diboride surface

Science.gov (United States)

Nguyen, Duc; Mallek, Justin; Cloud, Andrew N.; Abelson, John R.; Girolami, Gregory S.; Lyding, Joseph; Gruebele, Martin

2014-11-01

Direct visualization of the dynamics of structural glasses and amorphous solids on the sub-nanometer scale provides rich information unavailable from bulk or conventional single molecule techniques. We study the surface of hafnium diboride, a conductive ultrahigh temperature ceramic material that can be grown in amorphous films. Our scanning tunneling movies have a second-to-hour dynamic range and single-point current measurements extend that to the millisecond-to-minute time scale. On the a-HfB2 glass surface, two-state hopping of 1-2 nm diameter cooperatively rearranging regions or "clusters" occurs from sub-milliseconds to hours. We characterize individual clusters in detail through high-resolution (single cluster vertical displacements, we can reconstruct the local free energy landscape of individual clusters, complete with activation barrier height, a reaction coordinate in nanometers, and the shape of the free energy landscape basins between which hopping occurs. The experimental images are consistent with the compact shape of α-relaxors predicted by random first order transition theory, whereas the rapid hopping rate, even taking less confined motion at the surface into account, is consistent with β-relaxations. We make a proposal of how "mixed" features can show up in surface dynamics of glasses.

About the structure and stability of complex carbonates of thorium (IV), cerium (IV), zirconium (IV), hafnium (IV)

International Nuclear Information System (INIS)

Dervin, Jacqueline

1972-01-01

This research thesis addressed the study of complex carbonates of cations of metals belonging to the IV A column, i.e. thorium (IV), zirconium (IV), hafnium (IV), and also cerium (IV) and uranium (VI), and more particularly focused on ionic compounds formed in solution, and also on the influence of concentration and nature of cations on stability and nature of the formed solid. The author first presents methods used in this study, discusses their precision and scope of validity. She reports the study of the formation of different complex ions which have been highlighted in solution, and the determination of their formation constants. She reports the preparation and study of the stability domain of solid complexes. The next part reports the use of thermogravimetric analysis, IR spectrometry, and crystallography for the structural study of these compounds

A search for long-lived radionuclides produced by fast-neutron irradiations of copper, silver, europium, terbium, and hafnium

International Nuclear Information System (INIS)

Meadows, J.W.; Smith, D.L.; Ikeda, Y.; Konno, C.

1990-01-01

Identical sample packets, each containing samples of elemental copper, silver, europium, terbium, and hafnium, as well as titanium, iron and nickel as dosimeters, have been irradiated in three distinct accelerator neutron fields (at Argonne National Laboratory and Los Alamos National Laboratory in the U.S.A., and Japan Atomic Energy Research Institute, Tokai, Japan) as part of an interlaboratory research collaboration to search for the production of long-lived radionuclides for fusion waste disposal applications. This paper is a progress report on this project. To date, we have detected the following activities, and have obtained preliminary experimental cross section values for several of these: Ag-106m,108m,110m; Eu-150m,152g,154; Tb-158,160; and Hf-175,178m2,179m2,181. (author). 11 refs, 1 fig., 4 tabs

Intravitreal injection of a chimeric phage endolysin Ply187 protects mice from Staphylococcus aureus endophthalmitis

Science.gov (United States)

Objectives: The treatment of endophthalmitis is becoming very challenging due to the emergence of multidrug-resistant bacteria. Hence, the development of novel therapeutic alternatives for ocular use is essential. Here, we evaluated the therapeutic potential of Ply187AN-KSH3b, a chimeric phage endol...

In vitro metabolism of 2,2',3,4',5,5',6-heptachlorobiphenyl(CB187) with liver microsomes of rats, hamsters and guinea pigs

Energy Technology Data Exchange (ETDEWEB)

Koga, N.; Ohta, C.; Kanamaru, T. [Nakamura Gakuen Univ., Fukuoka (Japan); Haraguchi, K. [Daiichi Coll. of Pharmaceutical Sciences, Fukuoka (Japan); Kato, Y.; Yamada, S. [Univ. of Shizuoka, Shizuoka (Japan)

2004-09-15

PCB congeners possess extremely high lipophilicity and biological stability, and as a result they are not easily eliminated from the body once ingested. In particular, not only 2,4,5-trichlorosubstituted but also 6 or more chlorine-substituted PCBs such as 2,2',3',4,4',5-hexa-chlorobiphenyl (hexaCB) (CB138), 2,2',4,4',5,5'-hexaCB (CB153), 2,2',3,4,4',5,5'-heptachloro-biphenyl (heptaCB) (CB180) and 2,2',3,4',5,5',6-heptaCB (CB187) have been detected in blood and adipose tissues of mammals and human mother's milk at higher concentration. In addition, the 4-hydroxy (OH)-metabolite of CB187 has been reported to be present in human blood at the highest concentration of that derived from other PCB congeners. Although CB187, a tri-ortho-PCB, is one of the minor component in the commercial PCB preparations such as Clophen, Aroclor and Kanechlor, the toxic equivalency factor (TEF) which is used for dioxin-like PCB congeners including coplanar-PCBs and mono-ortho-PCBs to assess the potency of the toxicity has not been set up for di- and tri-ortho-PCB congeners. These facts indicate that 4-OH-PCB187 become more persistent and more important toxicologically than the parent CB187. However, there is little report about biotransformation in vivo or in vitro of CB187 in animals. Therefore, we examined CB187 metabolism by liver microsomes of rats, hamsters and guinea pigs.

Ferroelectric transistors with monolayer molybdenum disulfide and ultra-thin aluminum-doped hafnium oxide

Science.gov (United States)

Yap, Wui Chung; Jiang, Hao; Liu, Jialun; Xia, Qiangfei; Zhu, Wenjuan

2017-07-01

In this letter, we demonstrate ferroelectric memory devices with monolayer molybdenum disulfide (MoS2) as the channel material and aluminum (Al)-doped hafnium oxide (HfO2) as the ferroelectric gate dielectric. Metal-ferroelectric-metal capacitors with 16 nm thick Al-doped HfO2 are fabricated, and a remnant polarization of 3 μC/cm2 under a program/erase voltage of 5 V is observed. The capability of potential 10 years data retention was estimated using extrapolation of the experimental data. Ferroelectric transistors based on embedded ferroelectric HfO2 and MoS2 grown by chemical vapor deposition are fabricated. Clockwise hysteresis is observed at low program/erase voltages due to slow bulk traps located near the 2D/dielectric interface, while counterclockwise hysteresis is observed at high program/erase voltages due to ferroelectric polarization. In addition, the endurances of the devices are tested, and the effects associated with ferroelectric materials, such as the wake-up effect and polarization fatigue, are observed. Reliable writing/reading in MoS2/Al-doped HfO2 ferroelectric transistors over 2 × 104 cycles is achieved. This research can potentially lead to advances of two-dimensional (2D) materials in low-power logic and memory applications.

Os{sup 187}-isotope abundances in terrestrial and meteoritic osmium and an attempt to determine Re/Os-ages of iron meteorites; Anomalies dans l'abondance isotopique de l'osmium-187 dans l'osmium terrestre et meteoritique - Essai de determination de l'age des meteorites de fer au moyen du rapport Re/Os; Anomalii v rasprostranennosti izotopa osmiya-187 v zemnom i meteoritnom osmie i popytka opredeleniya vozrastov reniya/osmiya v zheleznykh meteoritakh; Anomalias en la abundancia isotopica del {sup 187}Os en el osmio terrestre y meteoritico. Ensayo para determinar la edad de los meteoritos de hierro por medio de la razon Re Os

Energy Technology Data Exchange (ETDEWEB)

Herr, W; Hoffmeister, W; Langhoff, J [Max-Planck-Institut fuer Chemie (Otto-Hahn-Institut) Mainz, Federal Republic of Germany (Germany); Geiss, J; Hirt, B; Houtermans, F G [Physikalisches Institut der Universitaet Bern (Switzerland)

1962-01-15

The isotopic composition of a large number of Os-samples from terrestrial platinum ores and from iron meteorites has been investigated by mass-spectrometry. The observed isotope-ratios Os{sup 187}:Os{sup 186} in Os/Ir-ores and in Os-samples, extracted quantitatively from iron meteorites, vary in limit from 0.88 to 1.41. These variations may be explained by the production of radiogenic Os following the decay of Re{sup 187}, a natural {beta}-emitter with the lowest known {beta}-energy. Neutron activation analysis proves that Re and Os are common trace elements in iron meteorites. As dating of these bodies by conventional methods suffers from enormous difficulties, the application of the Re/Os method has been studied. From our experiments a primordial Os{sup 187}:Os{sup 186} ratio is assumed and 'minimum ages' are discussed. They differ widely and are found presumably in the range from 3.7 to 5.6x10{sup 9} yr. (author) [French] Les auteurs ont etudie au moyen de la spectrometrie de masse la composition isotopique d'un grand nombre d'echantillons d'osmium provenant de minerais terrestres de platine et d'holosideres. Le rapport isotopique osmium-187/ osmium-186 observe dans l'osmiure d'iridium et dans les echantillons d'osmium extraits en quantite mesurable des holosideres varie entre 0,88 et 1,41. Ces variations peuvent etre expliquees par la production d'osmium radiogenicjue resultant de la desintegration du rhenium-187, emetteur naturel de rayonnements beta connu comme ayant la plus faible energie beta. L'analyse par activation des neutrons montre que le rhenium et l'osmium se trouvent communement a l'etat de traces dans les holosideres. Comme il est extremement difficile d'evaluer l'age de ces corps en recourant aux methodes classiques, les auteurs du memoire ont examine la possibilite d'utiliser le rapport Re/Os. Apres avoir assume de leurs experiences le rapport osmium-187/osmium-186, ils examinent la question des . Ceux-ci different sensiblement et

187Os/188Os of boninites from the Izu-Bonin-Mariana forearc, IODP Exp 352

Science.gov (United States)

Niles, D. E.; Nelson, W. R.; Reagan, M. K.; Pearce, J. A.; Godard, M.; Shervais, J. W.

2016-12-01

The Izu-Bonin-Mariana (IBM) subduction zone is an ideal laboratory in which to study the evolution of a subduction zone from its initiation to the development of modern-day arc volcanism. Boninite lavas were produced in the IBM forearc region during the early stages of subduction and are thought to have been generated by flux melting the previously depleted mantle wedge. Mariana forearc mantle peridotites record unradiogenic 187Os/188Os signatures (0.1193-0.1273) supporting the existence of variably depleted mantle in this region (Parkinson et al., 1998). In order to understand the connection between the regional mantle, slab-derived fluids, and the generation of boninites, Re-Os isotopic data were measured on subset of boninite-series lavas obtained during IODP Expedition 352. Preliminary age-corrected (48 Ma) 187Os/188Os isotopic data for boninite-series lavas (sites U1439C and U1442A) are unradiogenic to modestly radiogenic (0.1254-0.1390) compared to primitive mantle (0.1296), consistent with Os isotopic data from boninite sands from the Bonin Islands (0.1279-0.1382; Suzuki et al., 2011). The least radiogenic boninites have 187Os/188Os (< 0.1296) values consistent with average MORB mantle recorded globally by abyssal peridotites (0.1238 ± 0.0042; Rudnick & Walker, 2009). However, boninite lavas were not derived from the most refractory ancient mantle recorded by Mariana peridotites. Unradiogenic boninites generally have higher Os abundances (0.043-0.567 ppb), whereas more radiogenic boninites have low Os abundances (0.015-0.036). Due to their low Os abundances, the moderately radiogenic isotopic signatures may be the result of interaction with highly radiogenic seawater or incorporation of radiogenic sediment (e.g. Suzuki et al. 2011). However, the radiogenic values could also be the result of fluid flux from the subducting Pacific plate.

Outline of ATE Novoronezh Training Centre simulator V-187 upgrade project

International Nuclear Information System (INIS)

2006-01-01

Full-scope simulator V-187 was put into operation in 1987. Novovoronezh NPP Unit 5 is the reference unit for the simulator. The following is included into the simulator computer engineering: - central computer IBM 4381 to calculate the simulator mathematical models and to maintain the Instructor's Workstation; - 2 computers CM-2M to control the graphical information display subsystem; - 3 computers (object link computing terminal) to control the analog and discrete information input-output; - specially designed devices of discrete information compression to connect OLCT computers with control panel; - alpha-digital display of IBM 4381 computer is used as Instructor's Work-station. Computer languages: FORTRAN, Assembler

Temporal record of osmium concentrations and 187Os/188Os in organic-rich mudrocks: Implications for the osmium geochemical cycle and the use of osmium as a paleoceanographic tracer

Science.gov (United States)

Lu, Xinze; Kendall, Brian; Stein, Holly J.; Hannah, Judith L.

2017-11-01

We present a compilation of 192Os concentrations (representing non-radiogenic Os) and initial 187Os/188Os isotope ratios from organic-rich mudrocks (ORM) to explore the evolution of the Os geochemical cycle during the past three billion years. The initial 187Os/188Os isotope ratio of a Re-Os isochron regression for ORM constrains the local paleo-seawater 187Os/188Os, which is governed by the relative magnitudes of radiogenic Os (old continental crust) and unradiogenic Os (mantle, extraterrestrial, and juvenile/mafic/ultramafic crust) fluxes to seawater. A first-order increase in seawater 187Os/188Os ratios occurs from the Archean to the Phanerozoic, and may reflect a combination of increasing atmosphere-ocean oxygenation and weathering of progressively more radiogenic continental crust due to in-growth of 187Os from radioactive decay of 187Re. Superimposed on this long-term trend are shorter-term fluctuations in seawater 187Os/188Os ratios as a result of climate change, emplacement of large igneous provinces, bolide impacts, tectonic events, changes in seafloor spreading rates, and lithological changes in crustal terranes proximal to sites of ORM deposition. Ediacaran-Phanerozoic ORM have mildly higher 192Os concentrations overall compared with pre-Ediacaran Proterozoic ORM based on the mean and 95% confidence interval of 10,000 median values derived using a bootstrap analysis for each time bin (insufficient Archean data exist for robust statistical comparisons). However, there are two groups with anomalously high 192Os concentrations that are distinguished by their initial 187Os/188Os isotope ratios. Ediacaran-Cambrian ORM from South China have radiogenic initial 187Os/188Os, suggesting their high 192Os concentrations reflect proximal Os-rich crustal source(s), ultraslow sedimentation rates, and/or other unusual depositional conditions. In contrast, the unradiogenic initial 187Os/188Os and high 192Os concentrations of some Mesozoic ORM can be tied to emplacement

IER-297 CED-2: Final Design for Thermal/Epithermal eXperiments with Jemima Plates with Polyethylene and Hafnium

Energy Technology Data Exchange (ETDEWEB)

Nelson, A. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Percher, C. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Zywiec, W. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Heinrichs, D. P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2018-01-11

This report presents the final design (CED-2) for IER-297, and focuses on 15 critical configurations using highly enriched uranium (HEU) Jemima plates moderated by polyethylene with and without hafnium diluent. The goal of the U.S. Nuclear Criticality Safety Program’s Thermal/Epithermal eXperiments (TEX) is to design and conduct new critical experiments to address high priority nuclear data needs from the nuclear criticality safety and nuclear data communities, with special emphasis on intermediate energy (0.625 eV – 100 keV) assemblies that can be easily modified to include various high priority diluent materials. The TEX (IER 184) CED-1 Report [1], completed in 2012, demonstrated the feasibility of meeting the TEX goals with two existing NCSP fissile assets, plutonium Zero Power Physics Reactor (ZPPR) plates and highly enriched uranium (HEU) Jemima plates. The first set of TEX experiments will focus on using the plutonium ZPPR plates with polyethylene moderator and tantalum diluents.

Improved DC performance of AlGaN/GaN high electron mobility transistors using hafnium oxide for surface passivation

International Nuclear Information System (INIS)

Liu, Chang; Chor, Eng Fong; Tan, Leng Seow

2007-01-01

Improved DC performance of AlGaN/GaN high electron mobility transistors (HEMTs) have been demonstrated using reactive-sputtered hafnium oxide (HfO 2 ) thin film as the surface passivation layer. Hall data indicate a significant increase in the product of sheet carrier concentration (n s ) and electron mobility (μ n ) in the HfO 2 -passivated HEMTs, compared to the unpassivated HEMTs. This improvement in electron carrier characteristics gives rise to a 22% higher I Dmax and an 18% higher g mmax in HEMTs with HfO 2 passivation relative to the unpassivated devices. On the other hand, I gleak of the HEMTs decreases by nearly one order of magnitude when HfO 2 passivation is applied. In addition, drain current is measured in the subthreshold regime. Compared to the unpassivated HEMTs, HfO 2 -passivated HEMTs exhibit a much smaller off-state I D , indicating better turn-off characteristics

Protective coatings of hafnium dioxide by atomic layer deposition for microelectromechanical systems applications

Energy Technology Data Exchange (ETDEWEB)

Berdova, Maria, E-mail: maria.berdova@aalto.fi [Aalto University, Department of Materials Science and Engineering, 02150, Espoo (Finland); Wiemer, Claudia; Lamperti, Alessio; Tallarida, Grazia; Cianci, Elena [Laboratorio MDM, IMM CNR, Via C. Olivetti 2, 20864, Agrate Brianza, MB (Italy); Lamagna, Luca; Losa, Stefano; Rossini, Silvia; Somaschini, Roberto; Gioveni, Salvatore [STMicroelectronics, Via C. Olivetti 2, 20864, Agrate Brianza, MB (Italy); Fanciulli, Marco [Laboratorio MDM, IMM CNR, Via C. Olivetti 2, 20864, Agrate Brianza, MB (Italy); Università degli studi di Milano Bicocca, Dipartimento di Scienza dei Materiali, 20126, Milano (Italy); Franssila, Sami, E-mail: sami.franssila@aalto.fi [Aalto University, Department of Materials Science and Engineering, 02150, Espoo (Finland)

2016-04-15

Graphical abstract: - Highlights: • Atomic layer deposition of HfO{sub 2} from (CpMe){sub 2}Hf(OMe)Me or Hf(NMeEt){sub 4} and ozone for potential applications in microelectromechanical systems. • ALD HfO{sub 2} protects aluminum substrates from degradation in moist environment and at the same time retains good reflectance properties of the underlying material. • The resistance of hafnium dioxide to moist environment is independent of chosen precursors. - Abstract: This work presents the investigation of HfO{sub 2} deposited by atomic layer deposition (ALD) from either HfD-CO4 or TEMAHf and ozone for microelectromechanical systems (MEMS) applications, in particular, for environmental protection of aluminum micromirrors. This work shows that HfO{sub 2} films successfully protect aluminum in moist environment and at the same time retain good reflectance properties of underlying material. In our experimental work, the chemical composition, crystal structure, electronic density and roughness of HfO{sub 2} films remained the same after one week of humidity treatment (relative humidity of 85%, 85 °C). The reflectance properties underwent only minor changes. The observed shift in reflectance was only from 80–90% to 76–85% in 400–800 nm spectral range when coated with ALD HfO{sub 2} films grown with Hf(NMeEt){sub 4} and no shift (remained in the range of 68–83%) for films grown from (CpMe){sub 2}Hf(OMe)Me.

Effect of tungsten-187 in primary coolant on dose rate build-up in Vandellos 2

International Nuclear Information System (INIS)

Fernandez Lillo, E.; Llovet, R.; Boronat, M.

1994-01-01

The present work proposes a relationship between the Cobalt-60 piping deposited activity and the relatively high levels of Tungsten-187 in the coolant of Vandellos 2. The conclusions of this work can be applicable to other plants, since it proposes a tool to estimate and quantify the contribution of stellite to the generation of Cobalt-60 and the radiation dose build-up. (authors). 7 figs., 6 refs

Addendum 2 to CSER 79-002: Extension of the 150 gram fissile limit used in room 187 of PFP

International Nuclear Information System (INIS)

Friar, D.E.

1994-01-01

The PFP operating organization requests that the limit set permitting 150 grams fissile be extended to the Hoods 4 and 5 of Room 187. The request for the limit change is explained in the attached request for analysis

Efficient UV-emitting X-ray phosphors: octahedral Zr(PO4)6 luminescence centers in potassium hafnium-zirconium phosphates K2Hf1-xZrx(PO4)2 and KHf2(1-x)Zr2x(PO4)3

International Nuclear Information System (INIS)

Torardi, C.C.; Miao, C.R.; Li, J.

2003-01-01

Potassium hafnium-zirconium phosphates, K 2 Hf 1-x Zr x (PO 4 ) 2 and KHf 2(1-x) Zr 2x (PO 4 ) 3 , are broad-band UV-emitting phosphors. At room temperature, they have emission peak maxima at approximately 322 and 305 nm, respectively, under 30 kV peak molybdenum X-ray excitation. Both phosphors demonstrate luminescence efficiencies that make them up to ∼60% as bright as commercially available CaWO 4 Hi-Plus. The solid-state and flux synthesis conditions, and X-ray excited UV luminescence of these two phosphors are discussed. Even though the two compounds have different atomic structures, they contain zirconium in the same active luminescence environment as that found in highly efficient UV-emitting BaHf 1-x Zr x (PO 4 ) 2 . All the three materials have hafnium and zirconium in octahedral coordination via oxygen-atom corner sharing with six separate PO 4 tetrahedra. This octahedral Zr(PO 4 ) 6 moiety appears to be an important structural element for efficient X-ray excited luminescence, as are the edge-sharing octahedral TaO 6 chains for tantalate emission

187Re - 232Th - 238U nuclear geochronometry: constraining magmatism in East-Antarctica and the break-up of Gondwana

Science.gov (United States)

Roller, Goetz

2017-04-01

187Re - 232Th - 238U nuclear geochronometry is a new dating method for astronomy, earth and planetary sciences [1-4]. Nucleogeochronometric Rhenium-Osmium two-point-isochron (TPI) ages are calculated using a nuclear geochronometer as one data point in a two-point-isochron diagram [5-7]. The IVREA chronometer, for example, is one of five terrestrial nuclear geochronometers identified so far [8]. Here, it is used to constrain the magmatism of the Ferrar flood basalt province, which has been related to continental rifting and the break-up of Gondwana in the Jurassic.TPI ages for seven (basaltic) andesite whole rock samples from the Prince Albert Mountains (Victoria Land, Antarctica) are calculated. An isochron age of 172 ± 5 Ma (187Os/188Osi = 0.194 ± 0.023) has previously been published for these rocks [9]. Initial TPI 187Os/188Osi ratios show only minor scatter between 187Os/188Osi = 0.2149 ± 0.0064 and 187Os/188Osi = 0.22231 ± 0.00080, in agreement with the enigmatic, suprachondritic 187Os/188Osi = 0.194 ± 0.023 from the isochron [9]. TPI ages for the Mount Joyce samples range from 125.4 ± 9.9 Ma to 139 ± 17 Ma and thus constrain the youngest magmatic event(s) in the Transantarctic Mountains. For the Thumb Point basalt, a TPI age of 219 ± 81 Ma is calculated. Despite of its large uncertainty, the age itself is in agreement with the Triassic 224 Ma and 240 Ma events reported from North Patagonia [10]. The TPI age of 186.1 ± 8.1 Ma from the Ricker Hill basalt can be clearly distinguished from the Mount Murray TPI age of 158 ± 14 Ma, while at Brimstone Peak two TPI age groups of 155 ± 14 Ma and 175.3 ± 3.1 Ma are observed. From this it may be concluded that the seven TPI ages indicate episodic magmatic activity in East-Antarctica between 125 Ma and 219 Ma, leading to the break-up of Gondwana. This picture is consistent with the geochronology of the Antarctic Peninsula, Patagonia, the Karoo and the Ferrar mafic rocks [10]. Thus, besides constraining

Carriers of the Complex Allele HFE c.[187C>G;340+4T>C] Have Increased Risk of Iron Overload in São Miguel Island Population (Azores, Portugal).

Science.gov (United States)

Branco, Claudia C; Gomes, Cidália T; De Fez, Laura; Bulhões, Sara; Brilhante, Maria José; Pereirinha, Tânia; Cabral, Rita; Rego, Ana Catarina; Fraga, Cristina; Miguel, António G; Brasil, Gracinda; Macedo, Paula; Mota-Vieira, Luisa

2015-01-01

Iron overload is associated with acquired and genetic conditions, the most common being hereditary hemochromatosis (HH) type-I, caused by HFE mutations. Here, we conducted a hospital-based case-control study of 41 patients from the São Miguel Island (Azores, Portugal), six belonging to a family with HH type-I pseudodominant inheritance, and 35 unrelated individuals fulfilling the biochemical criteria of iron overload compatible with HH type-I. For this purpose, we analyzed the most common HFE mutations- c.845G>A [p.Cys282Tyr], c.187C>G [p.His63Asp], and c.193A>T [p.Ser65Cys]. Results revealed that the family's HH pseudodominant pattern is due to consanguineous marriage of HFE-c.845G>A carriers, and to marriage with a genetically unrelated spouse that is a -c.187G carrier. Regarding unrelated patients, six were homozygous for c.845A, and three were c.845A/c.187G compound heterozygous. We then performed sequencing of HFE exons 2, 4, 5 and their intron-flanking regions. No other mutations were observed, but we identified the -c.340+4C [IVS2+4C] splice variant in 26 (74.3%) patients. Functionally, the c.340+4C may generate alternative splicing by HFE exon 2 skipping and consequently, a protein missing the α1-domain essential for HFE/ transferrin receptor-1 interactions. Finally, we investigated HFE mutations configuration with iron overload by determining haplotypes and genotypic profiles. Results evidenced that carriers of HFE-c.187G allele also carry -c.340+4C, suggesting in-cis configuration. This data is corroborated by the association analysis where carriers of the complex allele HFE-c.[187C>G;340+4T>C] have an increased iron overload risk (RR = 2.08, 95% CI = 1.40-2.94, poverload because they will produce two altered proteins--the p.63Asp [c.187G], and the protein lacking 88 amino acids encoded by exon 2. In summary, we provide evidence that the complex allele HFE-c.[187C>G;340+4T>C] has a role, as genetic predisposition factor, on iron overload in the S�

186Os and 187Os enrichments and high-3He/4He sources in the Earth's mantle

DEFF Research Database (Denmark)

Brandon, A.D.; Graham, D.W.; Waight, Tod Earle

2007-01-01

at present remains core-mantle interaction. While some plumes with high 3He/4He, such as Hawaii, appear to have been subjected to detectable addition of Os (and possibly He) from the outer core, others such as Iceland do not. A positive correlation between 187Os/188Os and 3He/4He from 9.6 to 19 Ra in Iceland...

Recovery of metal chlorides from their complexes by molten salt displacement

International Nuclear Information System (INIS)

McLaughlin, D.F.; Stoltz, R.A.

1989-01-01

This patent describes a process for recovering zirconium or hafnium chloride from a complex of zirconium or hafnium tetrachloride and phosphorus oxychloride. The process comprising: introducing liquid complex of zirconium or hafnium tetrachloride and phosphorus oxychloride into an upper portion of a feed column containing zirconium or hafnium tetrachloride vapor and phosphorus oxychloride vapor. The liquid complex absorbing zirconium or hafnium tetrachloride vapor and producing a bottoms liquid and also producing a phosphorus oxychloride vapor stripped of zirconium or hafnium tetrachloride; introducing the bottoms liquid into a molten salt containing displacement reactor, the reactor containing molten salt comprising at least 30 mole percent lithium chloride and at least 30 mole percent of at least one other alkali metal chloride, the reactor being heated to 30-450 0 C to displace phosphorus oxychloride from the complex and product zirconium or hafnium tetrachloride vapor and phosphorus oxychloride vapor and zirconium or hafnium tetrachloride-containing molten salt; introducing the zirconium or hafnium tetrachloride vapor and the phosphorus oxychloride vapor into the feed column below the point of introduction of the liquid stream; introducing the zirconium or hafnium tetrachloride containing-molten salt into a recovery vessel where zirconium or hafnium tetrachloride is removed from the molten salt to produce zirconium or hafnium tetrachloride product and zirconium or hafnium chloride-depleted molten salt; and recycling the zirconium or hafnium tetachloride-depleted molten salt to the displacement reactor

Determination of osmium concentrations and (187)Os/(188)Os of crude oils and source rocks by coupling high-pressure, high-temperature digestion with sparging OsO(4) into a multicollector inductively coupled plasma mass spectrometer.

Science.gov (United States)

Sen, Indra S; Peucker-Ehrenbrink, Bernhard

2014-03-18

The (187)Os/(188)Os ratio that is based on the β(-)-decay of (187)Re to (187)Os (t1/2 = 41.6 billion years) is widely used to investigate petroleum system processes. Despite its broad applicability to studies of hydrocarbon deposits worldwide, a suitable matrix-matched reference material for Os analysis does not exist. In this study, a method that enables Os isotope measurement of crude oil with in-line Os separation and purification from the sample matrix is proposed. The method to analyze Os concentration and (187)Os/(187)Os involves sample digestion under high pressure and high temperature using a high pressure asher (HPA-S, Anton Paar), sparging of volatile osmium tetroxide from the sample solution, and measurements using multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). This methods significantly reduced the total procedural time compared to conventional Carius tube digestion followed by Os separation and purification using solvent extraction, microdistillation and N-TIMS analysis. The method yields Os concentration (28 ± 4 pg g(-1)) and (187)Os/(188)Os (1.62 ± 0.15) of commercially available crude oil reference material NIST 8505 (1 S.D., n = 6). The reference material NIST 8505 is homogeneous with respect to Os concentration at a test portion size of 0.2 g. Therefore, (187)Os/(188)Os composition and Os concentration of NIST 8505 can serve as a matrix-matched reference material for Os analysis. Data quality was assessed by repeated measurements of the USGS shale reference material SCo-1 (sample matrix similar to petroleum source rock) and the widely used Liquid Os Standard solution (LOsSt). The within-laboratory reproducibility of (187)Os/(188)Os for a 5 pg of LOsSt solution, analyzed with this method over a period of 12 months was ∼1.4% (1 S.D., n = 26), respectively.

Growth of HfO{sub x} thin films by reactive molecular beam epitaxy

Energy Technology Data Exchange (ETDEWEB)

Hildebrandt, Erwin; Kurian, Jose; Alff, Lambert [Institut fuer Materialwissenschaft, TU Darmstadt (Germany)

2008-07-01

Thin films of hafnium oxide were grown on single crystal r-cut and c-cut sapphire by reactive molecular beam epitaxy. The conditions for the growth of single oriented hafnium oxide thin films have been established. Hafnium oxide thin films were characterized by X-ray diffraction and optical absorption measurements. It was found that hafnium oxide thin films grown on r-cut sapphire were (00l) oriented whereas, on c-cut sapphire, hafnium oxide films showed different orientations depending on the growth temperature and oxidation conditions. The hafnium oxide films grown at higher temperature and under strong oxidation conditions yielded (001) oriented films on c-cut sapphire whereas slightly weaker oxidation condition leads to (111) oriented hafnium oxide films. The bandgap deducted from optical absorption measurement carried out on hafnium oxide films grown under optimized conditions agreed well with the values reported in literature. A range of oxygen deficient thin films of hafnium oxide were also grown on single crystal sapphire substrates in order to investigate the effect of oxygen vacancies on dielectric properties of hafnium oxide. The oxygen deficient thin films of hafnium oxide show a decrease in bandgap with increase in oxygen deficiency.

Crystal structure of the S187F variant of human liver alanine: Aminotransferase associated with primary hyperoxaluria type I and its functional implications

Science.gov (United States)

Oppici, Elisa; Fodor, Krisztian; Paiardini, Alessandro; Williams, Chris; Voltattorni, Carla Borri; Wilmanns, Matthias; Cellini, Barbara

2013-01-01

The substitution of Ser187, a residue located far from the active site of human liver peroxisomal alanine:glyoxylate aminotransferase (AGT), by Phe gives rise to a variant associated with primary hyperoxaluria type I. Unexpectedly, previous studies revealed that the recombinant form of S187F exhibits a remarkable loss of catalytic activity, an increased pyridoxal 5′-phosphate (PLP) binding affinity and a different coenzyme binding mode compared with normal AGT. To shed light on the structural elements responsible for these defects, we solved the crystal structure of the variant to a resolution of 2.9 Å. Although the overall conformation of the variant is similar to that of normal AGT, we noticed: (i) a displacement of the PLP-binding Lys209 and Val185, located on the re and si side of PLP, respectively, and (ii) slight conformational changes of other active site residues, in particular Trp108, the base stacking residue with the pyridine cofactor moiety. This active site perturbation results in a mispositioning of the AGT-pyridoxamine 5′-phosphate (PMP) complex and of the external aldimine, as predicted by molecular modeling studies. Taken together, both predicted and observed movements caused by the S187F mutation are consistent with the following functional properties of the variant: (i) a 300- to 500-fold decrease in both the rate constant of L-alanine half-transamination and the kcat of the overall transamination, (ii) a different PMP binding mode and affinity, and (iii) a different microenvironment of the external aldimine. Proposals for the treatment of patients bearing S187F mutation are discussed on the basis of these results. Proteins 2013; 81:1457–1465. © 2013 Wiley Periodicals, Inc. PMID:23589421

Evaluation and Enhancement of the Oxygen Reduction Reaction Activity on Hafnium Oxide Nanoparticles Assisted by L(+)-lysine

International Nuclear Information System (INIS)

Chisaka, Mitsuharu; Itagaki, Noriaki

2016-01-01

Evaluation of the oxygen reduction reaction (ORR) on oxide compounds is difficult owing to the insulating nature of oxides. In this study, various amounts of L(+)-lysine were added to the precursor dispersion for the hydrothermal synthesis of hafnium oxide nanoparticles on reduced graphene oxide sheets (HfO_x–rGO) to coat the HfO_x catalysts with layers of carbon, thereby increasing the conductivity and number of active sites. When the mass ratio of L(+)-lysine to GO, R, was above 26, carbon layers were formed and the amount monotonically increased with increasing R, as noted by cyclic voltammogrametry. X-ray photoelectron spectroscopy and rotating disk electrode analyses revealed that pyrolysis produced ORR-active oxygen defects, whose formation was proposed to involve carbothermal reduction. When 53 ≤ R ≤ 210, HfO_x–rGO contained a similar amount of oxygen defects and ORR activity, as represented by an onset potential of 0.9 V versus the reversible hydrogen electrode in 0.1 mol dm"−"3 H_2SO_4. However, the number of active sites depended on R due to the amount of L(+)-lysine-derived carbon layers that increased both the number of active sites and resistivity towards oxygen diffusion.

Mechanistic Studies of Hafnium-Pyridyl Amido-Catalyzed 1-Octene Polymerization and Chain Transfer Using Quench-Labeling Methods.

Science.gov (United States)

Cueny, Eric S; Johnson, Heather C; Anding, Bernie J; Landis, Clark R

2017-08-30

Chromophore quench-labeling applied to 1-octene polymerization as catalyzed by hafnium-pyridyl amido precursors enables quantification of the amount of active catalyst and observation of the molecular weight distribution (MWD) of Hf-bound polymers via UV-GPC analysis. Comparison of the UV-detected MWD with the MWD of the "bulk" (all polymers, from RI-GPC analysis) provides important mechanistic information. The time evolution of the dual-detection GPC data, concentration of active catalyst, and monomer consumption suggests optimal activation conditions for the Hf pre-catalyst in the presence of the activator [Ph 3 C][B(C 6 F 5 ) 4 ]. The chromophore quench-labeling agents do not react with the chain-transfer agent ZnEt 2 under the reaction conditions. Thus, Hf-bound polymeryls are selectively labeled in the presence of zinc-polymeryls. Quench-labeling studies in the presence of ZnEt 2 reveal that ZnEt 2 does not influence the rate of propagation at the Hf center, and chain transfer of Hf-bound polymers to ZnEt 2 is fast and quasi-irreversible. The quench-label techniques represent a means to study commercial polymerization catalysts that operate with high efficiency at low catalyst concentrations without the need for specialized equipment.

Facile solvothermal synthesis of highly active and robust Pd1.87Cu0.11Sn electrocatalyst towards direct ethanol fuel cell applications

Science.gov (United States)

Jana, Rajkumar; Dhiman, Shikha; Peter, Sebastian C.

2016-08-01

Ordered intermetallic Pd1.87Cu0.11Sn ternary electrocatalyst has been synthesized by sodium borohydride reduction of precursor salts Pd(acac)2, CuCl2.2H2O and SnCl2 using one-pot solvothermal synthesis method at 220 °C with a reaction time of 24 h. To the best of our knowledge, here for the first time we report surfactant free synthesis of a novel ordered intermetallic ternary Pd1.87Cu0.11Sn nanoparticles. The ordered structure of the catalyst has been confirmed by powder x-ray diffraction, transmission electron microscopy (TEM). Composition and morphology of the nanoparticles have been confirmed through field emission scanning electron microscopy, energy-dispersive spectrometry and TEM. The electrocatalytic activity and stability of the ternary electrocatalyst towards ethanol oxidation in alkaline medium was investigated by cyclic voltammetry and chronoamperometry techniques. The catalyst is proved to be highly efficient and stable upto 500th cycle and even better than commercially available Pd/C (20 wt%) electrocatalysts. The specific and mass activity of the as synthesized ternary catalyst are found to be ∼4.76 and ∼2.9 times better than that of commercial Pd/C. The enhanced activity and stability of the ordered ternary Pd1.87Cu0.11Sn catalyst can make it as a promising candidate for the alkaline direct ethanol fuel cell application.

Characteristics of laser produced plasmas of hafnium and tantalum in the 1-7 nm region

Science.gov (United States)

Li, Bowen; Otsuka, Takamitsu; Sokell, Emma; Dunne, Padraig; O'Sullivan, Gerry; Hara, Hiroyuki; Arai, Goki; Tamura, Toshiki; Ono, Yuichi; Dinh, Thanh-Hung; Higashiguchi, Takeshi

2017-11-01

Soft X-ray (SXR) spectra from hafnium and tantalum laser produced plasmas were recorded in the 1-7 nm region using two Nd:YAG lasers with pulse lengths of 170 ps and 10 ns, respectively, operating at a range of power densities. The maximum focused peak power density was 2. 3 × 1014 W cm-2 for 170 ps pulses and 1. 8 × 1012 W cm-2 for 10 ns pulses, respectively. Two intense quasicontinuous intensity bands resulting from n = 4 - n = 4 and n = 4 - n = 5 unresolved transition arrays (UTAs) dominate both sets of experimental spectra. Comparison with calculations performed with the Cowan suite of atomic structure codes as well as consideration of previous experimental and theoretical results aided identification of the most prominent features in the spectra. For the 10 ns spectrum, the highest ion stage that could be identified from the n = 4 - n = 5 arrays were lower than silver-like Hf25+ and Ta26+ (which has a 4 d 104 f ground configuration) indicating that the plasma temperature attained was too low to produce ions with an outermost 4 d subshell, while for the 170 ps plasmas the presence of significantly higher stages was deduced and lines due to 4 d-5 p transitions were clearly evident. Furthermore, we show an enhancement of emission from tantalum using dual laser irradiation, and the effect of pre-pulse durations and delay times between two pulses are demonstrated.

X-ray tube target

International Nuclear Information System (INIS)

Weber, R.G.

1980-01-01

A target with an improved heat emissive surface for use in a rotating anode type x-ray tube is described. The target consists of a body having a first surface portion made of x-ray emissive material and a second surface portion made of a heat emissive material comprising at least one of hafnium boride, hafnium oxide, hafnium nitride, hafnium silicide, and hafnium aluminide. (U.K.)

Materials properties of hafnium and zirconium silicates: Metal interdiffusion and dopant penetration studies

Science.gov (United States)

Quevedo Lopez, Manuel Angel

Hafnium and Zirconium based gate dielectrics are considered potential candidates to replace SiO2 or SiON as the gate dielectric in CMOS processing. Furthermore, the addition of nitrogen into this pseudo-binary alloy has been shown to improve their thermal stability, electrical properties, and reduce dopant penetration. Because CMOS processing requires high temperature anneals (up to 1050°C), it is important to understand the diffusion properties of any metal associated with the gate dielectric in silicon at these temperatures. In addition, dopant penetration from the doped polysilicon gate into the Si channel at these temperatures must also be studied. Impurity outdiffusion (Hf, Zr) from the dielectric, or dopant (B, As, P) penetration through the dielectric into the channel region would likely result in deleterious effects upon the carrier mobility. In this dissertation extensive thermal stability studies of alternate gate dielectric candidates ZrSixOy and HfSixO y are presented. Dopant penetration studies from doped-polysilicon through HfSixOy and HfSixOyNz are also presented. Rutherford Backscattering Spectroscopy (RBS), Heavy Ion RBS (HI-RBS), X-ray Photoelectron Spectroscopy (XPS), High Resolution Transmission Electron Microscopy (HR-TEM), and Time of Flight and Dynamic Secondary Ion Mass Spectroscopy (ToF-SIMS, D-SIMS) methods were used to characterize these materials. The dopant diffusivity is calculated by modeling of the dopant profiles in the Si substrate. In this disseration is reported that Hf silicate films are more stable than Zr silicate films, from the metal interdiffusion point of view. On the other hand, dopant (B, As, and P) penetration is observed for HfSixO y films. However, the addition of nitrogen to the Hf - Si - O systems improves the dopant penetration properties of the resulting HfSi xOyNz films.

186Os- 187Os systematics of Gorgona Island komatiites: implications for early growth of the inner core

Science.gov (United States)

Brandon, Alan D.; Walker, Richard J.; Puchtel, Igor S.; Becker, Harry; Humayun, Munir; Revillon, Sidonie

2003-02-01

The presence of coupled enrichments in 186Os/ 188Os and 187Os/ 188Os in some mantle-derived materials reflects long-term elevation of Pt/Os and Re/Os relative to the primitive upper mantle. New Os data for the 89 Ma Gorgona Island, Colombia komatiites indicate that these lavas are also variably enriched in 186Os and 187Os, with 186Os/ 188Os ranging between 0.1198397±22 and 0.1198470±38, and with γOs correspondingly ranging from +0.15 to +4.4. These data define a linear trend that converges with the previously reported linear trend generated from data for modern Hawaiian picritic lavas and a sample from the ca. 251 Ma Siberian plume, to a common component with a 186Os/ 188Os of approximately 0.119870 and γOs of +17.5. The convergence of these data to this Os isotopic composition may imply a single ubiquitous source in the Earth's interior that mixes with a variety of different mantle compositions distinguished by variations in γOs. The 187Os- and 186Os-enriched component may have been generated via early crystallization of the solid inner core and consequent increases in Pt/Os and Re/Os in the liquid outer core, with time leading to suprachondritic 186Os/ 188Os and γOs in the outer core. The presence of Os from the outer core in certain portions of the mantle would require a mechanism that could transfer Os from the outer core to the lower mantle, and thence to the surface. If this is the process that generated the isotopic enrichments in the mantle sources of these plume-derived systems, then the current understanding of solid metal-liquid metal partitioning of Pt, Re and Os requires that crystallization of the inner core began prior to 3.5 Ga. Thus, the Os isotopic data reported here provide a new source of data to better constrain the timing of inner core formation, complementing magnetic field paleo-intensity measurements as data sources that constrain models based on secular cooling of the Earth.

Lifetime in 181Ir and 187Au: enhanced deformation of the πi 13/2 intruder orbital

International Nuclear Information System (INIS)

Walpe, J.C.; Garg, U.; Naguleswaran, S.; Ren, Q.W.

1995-01-01

Lifetimes have been measured in the πh 9/2 (yrast) and πi 13/2 (excited) bands in the nuclei 181 Ir and 187 Au using the Recoil Distance Method (RDM). The results clearly indicate that the πi 13/2 band exhibits an increased deformation over the πh 9/2 band, in keeping with the premise that the delayed crossing in this band is due to enhanced quadrupole deformation. (author). 3 refs, 1 fig, 2 tab

Lifetime embrittlement of reactor core materials

International Nuclear Information System (INIS)

Kreyns, P.H..; Bourgeois, W.F.; Charpentier, P.L.; Kammenzind, B.F.; Franklin, D.G.; White, C.J.

1994-08-01

Over a core lifetime, the reactor materials Zircaloy-2, Zircaloy-4, and hafnium may become embrittled due to the absorption of corrosion- generated hydrogen and to neutron irradiation damage. Results are presented on the effects of fast fluence on the fracture toughness of wrought Zircaloy-2, Zircaloy-4, and hafnium; Zircaloy-4 to hafnium butt welds; and hydrogen precharged beta treated and weld metal Zircaloy-4 for fluences up to a maximum of approximately 150 x 10 24 n/M 2 (> 1 Mev). While Zircaloy-4 did not exhibit a decrement in K IC due to irradiation, hafnium and butt welds between hafnium and Zircaloy-4 are susceptible to embrittlement with irradiation. The embrittlement can be attributed to irradiation strengthening, which promotes cleavage fracture in hafnium and hafnium-Zircaloy welds, and, in part, to the lower chemical potential of hydrogen in Zircaloy-4 compared to hafnium, which causes hydrogen, over time, to drift from the hafnium end toward the Zircaloy-4 end and to precipitate at the interface between the weld and base-metal interface. Neutron radiation apparently affects the fracture toughness of Zircaloy-2, Zircaloy-4, and hafnium in different ways. Possible explanations for these differences are suggested. It was found that Zircaloy-4 is preferred over Zircaloy-2 in hafnium-to- Zircaloy butt-weld applications due to its absence of a radiation- induced reduction in K IC plus its lower hydrogen absorption characteristics compared with Zircaloy-2

The energy landscape of glassy dynamics on the amorphous hafnium diboride surface

International Nuclear Information System (INIS)

Nguyen, Duc; Girolami, Gregory S.; Mallek, Justin; Cloud, Andrew N.; Abelson, John R.; Lyding, Joseph; Gruebele, Martin

2014-01-01

Direct visualization of the dynamics of structural glasses and amorphous solids on the sub-nanometer scale provides rich information unavailable from bulk or conventional single molecule techniques. We study the surface of hafnium diboride, a conductive ultrahigh temperature ceramic material that can be grown in amorphous films. Our scanning tunneling movies have a second-to-hour dynamic range and single-point current measurements extend that to the millisecond-to-minute time scale. On the a-HfB 2 glass surface, two-state hopping of 1–2 nm diameter cooperatively rearranging regions or “clusters” occurs from sub-milliseconds to hours. We characterize individual clusters in detail through high-resolution (<0.5 nm) imaging, scanning tunneling spectroscopy and voltage modulation, ruling out individual atoms, diffusing adsorbates, or pinned charges as the origin of the observed two-state hopping. Smaller clusters are more likely to hop, larger ones are more likely to be immobile. HfB 2 has a very high bulk glass transition temperature T g , and we observe no three-state hopping or sequential two-state hopping previously seen on lower T g glass surfaces. The electronic density of states of clusters does not change when they hop up or down, allowing us to calibrate an accurate relative z-axis scale. By directly measuring and histogramming single cluster vertical displacements, we can reconstruct the local free energy landscape of individual clusters, complete with activation barrier height, a reaction coordinate in nanometers, and the shape of the free energy landscape basins between which hopping occurs. The experimental images are consistent with the compact shape of α-relaxors predicted by random first order transition theory, whereas the rapid hopping rate, even taking less confined motion at the surface into account, is consistent with β-relaxations. We make a proposal of how “mixed” features can show up in surface dynamics of glasses

Three-dimensional superconductivity and vortex glass transition in La1.87Y0.13CuO4

International Nuclear Information System (INIS)

Lee, Hyun-Sook; Kim, Heon-Jung; Kim, Hyun-Jung; Jung, Myung-Hwa; Jo, Younghun; Lee, Sung-Ik; Tsukada, Akio; Naito, Michio

2006-01-01

The angular dependence of the critical current density (J c (θ)) and the vortex glass transition temperature (T g (θ)) in La 1.87 Y 0.13 CuO 4 were measured at different fields and temperatures. Both J c (θ) and T g (θ) showed a strong angular variation, which is typical for anisotropic superconductors. The angular variation could be described by using the anisotropic three-dimensional Ginzburg-Landau theory. From our analysis, we were able to estimate the anisotropy ratio

Cervical intervertebral disk herniation in chondrodystrophoid and nonchondrodystrophoid small-breed dogs: 187 cases (1993-2013).

Science.gov (United States)

Hakozaki, Takaharu; Iwata, Munetaka; Kanno, Nobuo; Harada, Yasuji; Yogo, Takuya; Tagawa, Masahiro; Hara, Yasushi

2015-12-15

To identify characteristics of chondrodystrophoid and nonchondrodystrophoid small-breed dogs with cervical intervertebral disk herniation (IVDH). Retrospective case series. 187 small-breed (≤ 15 kg [33 lb]) dogs that underwent surgery because of cervical IVDH. Medical records were reviewed for information on breed, sex, age, weight, location of affected intervertebral disks, duration and severity of neurologic signs, and recovery time. 55 of the 187 (29.4%) dogs were Beagles. The most frequently affected intervertebral disk was C2-3 (81/253 [32.0%]), and this was the more frequently affected intervertebral disk in dogs of several chondrodystrophoid breeds, including Beagles (29/66 [43.9%]), Dachshunds (13/37 [35.1%]), Shih Tzus (16/41 [39.0%]), and Pekingese (3/10 [30.0%]). However, caudal disks (C5-6 or C6-7) were more frequently affected in Yorkshire Terriers (13/24 [54.2%]) and Chihuahuas (9/13 [69%]). Shih Tzus and Yorkshire Terriers were significantly older at the time of surgery (mean ± SD age, 9.6 ± 2.3 years and 9.5 ± 2.5 years, respectively) than were Pomeranians (6.2 ± 2.3 years), and Yorkshire Terriers had a significantly higher number of affected disks (2.0 ± 0.9) than did Dachshunds (1.1 ± 0.3). Mean recovery time was significantly longer in Yorkshire Terriers (36.7 ± 13.0 days) than in Beagles (16.5 ± 17.1 days), Shih Tzus (17.8 ± 14.5 days), or Chihuahuas (12.2 ± 7. 2 days). Results suggested that there may be breed-specific differences in the characteristics of cervical IVDH in small-breed dogs.

Osteogenesis imperfecta Type IV: a newly identified variant at position c.560 (G > T; p.Gly187Val) in the COL1A2 gene.

Science.gov (United States)

Usta, Akin; Karademir, Dilay; Sen, Eylem; Yazici, Selcuk; Adali, Ertan; Erdem, Erkan; Karacan, Meric

2017-01-01

Osteogenesis imperfecta is a clinically heterogenous disease caused by defective collagen syntesis associated with a mutation in the COL1A1 or COL1A2 genes. In this report, we present a case of osteogenesis imperfecta (OI) type IV, seen in a female fetus with incurved femurs at 18 weeks of gestation. Molecular analysis of the newborn revealed a novel mutation at position c.560 (c.560 G > T) of the exon 12 in the COL1A2 gene; which lead to the glycine modification with valine (p.Gly187Val) at codon 187. The pregnancy follow-up was uneventful. After delivery, the newborn underwent biphosponat therapy and no fracture was detected until 1 year old.

MTH187 from Methanobacterium thermoautotrophicum has three HEAT-like Repeats

Energy Technology Data Exchange (ETDEWEB)

Julien, Olivier; Gignac, Isabelle [Universite Laval, Departement de biochimie et de microbiologie and CREFSIP (Canada); Hutton, Anna [University of Alberta, Institute for Biomolecular Design (Canada); Yee, Adelinda; Arrowsmith, Cheryl H. [University of Toronto, Division of Molecular and Structural Biology, Department of Medical Biophysics, Ontario Cancer Institute (Canada); Gagne, Stephane M. [Universite Laval, Departement de biochimie et de microbiologie and CREFSIP (Canada)], E-mail: sgagne@rsvs.ulaval.ca

2006-06-15

With the completion of genome sequencing projects, there are a large number of proteins for which we have little or no functional information. Since protein function is closely related to three-dimensional conformation, structural proteomics is one avenue where the role of proteins with unknown function can be investigated. In the present structural project, the structure of MTH187 has been determined by solution-state NMR spectroscopy. This protein of 12.4 kDa is one of the 424 non-membrane proteins that were cloned and purified for the structural proteomic project of Methanobacterium thermoautotrophicum [Christendat, D., Yee, A., Dharamsi, A., Kluger, Y., Gerstein, M., Arrowsmith, C.H. and Edwards, A.M. (2000) Prog. Biophys. Mol. Biol., 73, 339-345]. Methanobacterium thermoautotrophicum is a thermophilic archaeon that grows optimally at 65 deg. C. A particular characteristic of this microorganism is its ability to generate methane from carbon dioxide and hydrogen [Smith, D.R., Doucette-Stamm, L.A., Deloughery, C., Lee, H., Dubois, J., Aldredge, T., Bashirzadeh, R., Blakely, D., Cook, R., Gilbert, K., Harrison, D., Hoang, L., Keagle, P., Lumm, W., Pothier, B., Qiu, D., Spadafora, R., Vicaire, R., Wang, Y., Wierzbowski, J., Gibson, R., Jiwani, N., Caruso, A., Bush, D., Reeve, J. N. et al. (1997) J. Bacteriol., 179, 7135-7155].

The crystallochemical factor of strong keeping of radiogenic 187Os in the structure of rhenium-bearing molybdenites

International Nuclear Information System (INIS)

Val'ter, A.A.; Pisanskij, A.I.; Podberezskaya, N.V.

2007-01-01

To understand the possible cause of the strong keeping of radiogenic Os in comparison with initial Re in the molybdenite structure, we compare the cation positions in MoS 2 , ReS 2 , and OsS 2 and the geometry of 'empty' octahedra of the molybdenite structure. The similarity of 'empty' octahedra of MoS 2 and the Os environment in OsS 2 is determined. So, one can assume that knock-on atoms of 187 Os can be fixed in 'empty' octahedra by recoiling or the later thermal action

An Auger electron spectroscopy study on the anodization process of high-quality thin-film capacitors made of hafnium

International Nuclear Information System (INIS)

Noya, Atsushi; Sasaki, Katsutaka; Umezawa, Toshiji

1989-01-01

Formation process of the anodic oxide film of hafnium for use as a thin-film capacitor has been examined by the current-voltage characteristics of the anodization and the in-depth analysis of formed oxide using Auger electron spectroscopy. It is found that the oxide growth obeys three different rate laws such as the linear rate law at first and next the parabolic rate law during the constant current anodization, and then the reciprocal logarithmic rate law during the constant voltage anodization following after the constant current process. From the Auger electron spectroscopy analysis, it is found that the shape of the compositional depth profile of the grown oxide film varies associating with the rate law of oxidation obeyed. The variation of depth profile correlating with the rate law is discussed with respect to each elementary process such as the transport and/or the reaction of chemical species interpreted from the over-all behavior of anodization process. It is revealed that the stoichiometric film having an interface with sharp transition, which is favorable for obtaining excellent electrical properties of the capacitor, can be obtained under the condition that the phase-boundary reaction is the rate-determining step of the anodization. The constant voltage anodization process also satisfies such circumstances and therefore can be favorable method for preparing highquality thin-film capacitors. (author)

[Epidemiologic profile of the newborn of unmarried mother in Bizerta. About 187 cases].

Science.gov (United States)

Boujemaa, Zied; Aoun, Saida; Hammami, Olfa; Chebbi, Yasser; Zaghbib, A; Gandoura, Najoie

2006-10-01

The aim of this study is to establish the epidemiologic profile of 187 illegitimatepregnancies compared topregnancies from married mothers. A transversal retrospective study was carried out in Bizerta from 1990 to 2003. The witness group was constitued by women whose gonna delivery at the same period with p married mothers and has a rural origin and primiparous status. Pregnancy was not followed-up in 70.6% vs. 1.6% and maternal serology was done in 17% vs. 96.8%. 38.4% of new-borns of single mothers were hospitalised (vs. 13.2% in the group witness) for materno-foetal infection (14.4%), respiratory distress syndrome (11.7%), prematurity (9.6%) and intra-uterine growth delay (2.1%). The mortality rate in newborns of single mothers was 5.3%. Illegitimate pregnancy is not well followed-up, worst to live and comport a risk for the health and mental in mothers and newborns.

Contribution towards ALD and MOCVD of rare earth oxides and hafnium oxide. From precursor evaluation to process development and thin film characterization

International Nuclear Information System (INIS)

Xu, Ke

2013-01-01

elements for ALD applications. A possible synthesis route is the salt metatheses route. It could be expected that the monodentate guanidine ligand would provide increased reactivity towards water, where the bulky guanidine ligands will shield the RE center providing self-limiting growth behavior. In Chapter 4 and 7, ALD of rare earth oxides and hafnium oxide using corresponding guanidinate precursors are in detail investigated. According to the measurements, these processes are true ALD processes with broad ALD windows, high growth per cycle in the saturated area. Furthermore, the rare earth guanidinate and hafnium guanidinate precursors exhibit matching ALD window in the temperature range of 200 - 225 C. This motivated us to deposite trinary oxide thin films (HfREOx) using corresponding precursor combinations.

Human small cell lung cancer NYH cells selected for resistance to the bisdioxopiperazine topoisomerase II catalytic inhibitor ICRF-187 demonstrate a functional R162Q mutation in the Walker A consensus ATP binding domain of the alpha isoform

DEFF Research Database (Denmark)

Wessel, I; Jensen, L H; Jensen, P B

1999-01-01

in expression of the beta isoform. Sequencing of the entire topoisomerase IIalpha cDNA from NYH/187 cells demonstrated a homozygous G-->A point mutation at nucleotide 485, leading to a R162Q conversion in the Walker A consensus ATP binding site (residues 161-165 in the alpha isoform), this being the first drug......-selected mutation described at this site. Western blotting after incubation with ICRF-187 showed no depletion of the alpha isoform in NYH/187 cells in contrast to wild-type (wt) cells, whereas equal depletion of the beta isoform was observed in the two sublines. Alkaline elution assay demonstrated a lack...... of inhibition of etoposide-induced DNA single-stranded breaks in NYH/187 cells, whereas this inhibition was readily apparent in NYH cells. Site-directed mutagenesis in human topoisomerase IIalpha introduced into a yeast Saccharomyces cerevisiae strain with a temperature-conditional yeast TOP2 mutant...

Nano-crystals of cerium–hafnium binary oxide: Their size-dependent structure

Energy Technology Data Exchange (ETDEWEB)

Raitano, Joan M. [Department of Applied Physics and Applied Mathematics, Materials Science and Engineering Program, Columbia University, New York, NY 10027 (United States); Khalid, Syed [National Synchrotron Light Source, Brookhaven National Laboratory, Upton, NY 11973 (United States); Marinkovic, Nebojsa [Chemical Engineering Department, Columbia University, 500 W 120th St, Mudd 801, New York, NY 10027 (United States); Chan, Siu-Wai, E-mail: sc174@columbia.edu [Department of Applied Physics and Applied Mathematics, Materials Science and Engineering Program, Columbia University, New York, NY 10027 (United States)

2015-09-25

Highlights: • (1 − x)CeO{sub 2}–xHfO{sub 2} was precipitated (0 < x < 1) and calcined in air. • For x ⩽ 0.14, crystallites ⩽140 nm in size exhibit only the fluorite structure. • This low hafnia solubility is attributable to no auto-reduction (Ce{sup 3+} = 0). • The low solubility is also due to the high temperature required for homogenization. • Coarsening is lessened as Hf{sup 4+} ions slow cation diffusion in these crystallites. - Abstract: Cerium oxide (CeO{sub 2}, “ceria”) and hafnium oxide (HfO{sub 2}, “hafnia”) were aqueously co-precipitated and subsequently calcined to allow for homogenization. The size of the (1−x)CeO{sub 2}–xHfO{sub 2} crystallites, determined by the Scherrer equation, varied from 140 nm for x = 0 to 15 nm for x = 0.73. For x ⩽ 0.14, only cubic structures are visible in X-ray diffractograms, and the lattice parameters are consistent with the values expected for structurally cubic solid solutions of hafnia in ceria. At x = 0.26, tetragonal and monoclinic phases nucleated with the former not being observed in the bulk phase diagram for ceria–hafnia. Therefore, the solubility limit of the cubic structure is between x = 0.14 and x = 0.26 for 40–61 nm crystallites, the sizes of these respective compositions. More specifically, for the 40 nm crystallites of x = 0.26 (1 − x)CeO{sub 2}–xHfO{sub 2}, 15% of the hafnia remains in a structurally cubic solid solution with ceria based on the observed cubic lattice parameter. The compositional domain for the cubic fluorite structure in this study is narrower than other nanostructured (1 − x)CeO{sub 2}–xHfO{sub 2} studies, especially studies with crystallite sizes less than 10 nm, but wider than observed in the bulk and helps to expand the size regime over which the relationship between crystallite size and phase stability is known. The extent of this cubic-structure domain is mainly attributable to the intermediate crystallite size and the roughly zero Ce{sup 3

TEM-187, a new extended-spectrum β-lactamase with weak activity in a Proteus mirabilis clinical strain.

Science.gov (United States)

Corvec, Stéphane; Beyrouthy, Racha; Crémet, Lise; Aubin, Guillaume Ghislain; Robin, Frédéric; Bonnet, Richard; Reynaud, Alain

2013-05-01

A Proteus mirabilis clinical strain (7001324) was isolated from urine sample of a patient hospitalized in a long-term-care facility. PCR and cloning experiments performed with this strain identified a novel TEM-type β-lactamase (TEM-187) differing by four amino acid substitutions (Leu21Phe, Arg164His, Ala184Val, and Thr265Met) from TEM-1. This characterization provides further evidence for the diversity of extended-spectrum β-lactamases (ESBL) produced by P. mirabilis and for their potential spread to other Enterobacteriaceae due to a lack of sensitive detection methods used in daily practice.

Thermal neutron radiative capture cross-section of 186W(n, γ)187W reaction

International Nuclear Information System (INIS)

Tan, V H; Son, P N

2016-01-01

The thermal neutron radiative capture cross section for 186 W(n, γ) 187 W reaction was measured by the activation method using the filtered neutron beam at the Dalat research reactor. An optimal composition of Si and Bi, in single crystal form, has been used as neutron filters to create the high-purity filtered neutron beam with Cadmium ratio of R cd = 420 and peak energy E n = 0.025 eV. The induced activities in the irradiated samples were measured by a high resolution HPGe digital gamma-ray spectrometer. The present result of cross section has been determined relatively to the reference value of the standard reaction 197 Au(n, γ) 198 Au. The necessary correction factors for gamma-ray true coincidence summing, and thermal neutron self-shielding effects were taken into account in this experiment by Monte Carlo simulations. (paper)

L2₁ and XA Ordering Competition in Hafnium-Based Full-Heusler Alloys Hf₂VZ (Z = Al, Ga, In, Tl, Si, Ge, Sn, Pb).

Science.gov (United States)

Wang, Xiaotian; Cheng, Zhenxiang; Wang, Wenhong

2017-10-20

For theoretical designing of full-Heusler based spintroinc materials, people have long believed in the so-called Site Preference Rule (SPR). Very recently, according to the SPR, there are several studies on XA-type Hafnium-based Heusler alloys X₂YZ, i.e., Hf₂VAl, Hf₂CoZ (Z = Ga, In) and Hf₂CrZ (Z = Al, Ga, In). In this work, a series of Hf₂-based Heusler alloys, Hf₂VZ (Z = Al, Ga, In, Tl, Si, Ge, Sn, Pb), were selected as targets to study the site preferences of their atoms by first-principle calculations. It has been found that all of them are likely to exhibit the L2₁-type structure instead of the XA one. Furthermore, we reveal that the high values of spin-polarization of XA-type Hf₂VZ (Z = Al, Ga, In, Tl, Si, Ge, Sn, Pb) alloys have dropped dramatically when they form the L2₁-type structure. Also, we prove that the electronic, magnetic, and physics nature of these alloys are quite different, depending on the L2₁-type or XA-type structures.

Growth of conductive HfO{sub 2-x} thin films by reactive molecular beam epitaxy

Energy Technology Data Exchange (ETDEWEB)

Hildebrandt, Erwin; Kurian, Jose; Alff, Lambert [Institut fuer Materialwissenschaft, TU Darmstadt (Germany); Kleebe, Hans-Joachim [Institut fuer Angewandte Geowissenschaften, TU Darmstadt (Germany)

2009-07-01

Thin films of oxygen deficient hafnium oxide were grown on single crystal c-cut and r-cut sapphire substrates by reactive molecular beam epitaxy. The oxidation conditions during growth were varied within a wide range using RF-activated oxygen. Hafnium oxide thin films were characterized using X-ray diffraction, resistivity measurements ({rho}-T) and transmission electron microscopy (TEM). The results show a dramatic increase in conductivity of the deposited oxygen deficient hafnium oxide thin films with decreasing oxidation conditions during growth. The electrical properties of deficient hafnium oxide thin films varied from insulating over semiconducting to conducting. X-ray diffraction data as well as TEM data rule out the possibility of conductivity due to metallic hafnium.

Hafnium in peralkaline and peraluminous boro-aluminosilicate glass, and glass subcomponents: a solubility study

International Nuclear Information System (INIS)

Davis, Linda L.; Darab, John G.; Qian, Maoxu; Zhao, Donggao; Palenik, Christopher S.; Li, Hong; Strachan, Denis M.; Li, Liyu

2003-01-01

A relationship between the solubility of hafnia (HfO2) and the host glass composition was explored by determining the solubility limits of HfO2 in peralkaline and peraluminous borosilicate glasses in the system SiO2-Al2O3-B2O3-Na2O, and in glasses in the system SiO2-Na2O-Al2O3 in air at 1450 C. The only Hf-bearing phase to crystallize in the peralkaline borosilicate melts is hafnia, while in the boron-free melts sodium-hafnium silicates crystallize. All peraluminous borosilicate melts crystallize hafnia, but the slightly peraluminous glasses also have sector-zoned hafnia crystals that contain Al and Si. The more peraluminous borosilicate glasses also crystallize a B-containing mullite. The general morphology of the hafnia crystals changes as peralkalinity (Na2O/(Na2O+Al2O3)) decreases, as expected in melts with increasing viscosity. In all of the glasses with Na2O > Al2O3, the solubility of hafnia is linearly and positively correlated with Na2O/(Na2O + Al2O3) or Na2O - Al2O3 (excess sodium), despite the presence of 5 to 16 mol% B2O3. The solubility of hafnia is higher in the sodium-aluminum borosilicate glasses than in the sodium-aluminosilicate glasses, suggesting that the boron is enhancing the effect that excess sodium has on the incorporation of Hf into the glass structure. The results of this solubility study are compared to other studies of high-valence cation solubility in B-free silicate melts. From this, for peralkaline B-bearing glasses, it is shown that, although the solubility limits are higher, the solution behavior of hafnia is the same as in B-free silicate melts previously studied. By comparison, also, it is shown that in peraluminous melts, there must be a different solution mechanism for hafnia: different than for peralkaline sodium-aluminum borosilicate glasses and different than for B-free silicate melts studied by others

The geological record of base metal sulfides in the cratonic mantle: A microscale 187Os/188Os study of peridotite xenoliths from Somerset Island, Rae Craton (Canada)

Science.gov (United States)

Bragagni, A.; Luguet, A.; Fonseca, R. O. C.; Pearson, D. G.; Lorand, J.-P.; Nowell, G. M.; Kjarsgaard, B. A.

2017-11-01

We report detailed petrographic investigations along with 187Os/188Os data in Base Metal Sulfide (BMS) on four cratonic mantle xenoliths from Somerset Island (Rae Craton, Canada). The results shed light on the processes affecting the Re-Os systematics and provide time constraints on the formation and evolution of the cratonic lithospheric mantle beneath the Rae craton. When devoid of alteration, BMS grains mainly consist of pentlandite + pyrrhotite ± chalcopyrite. The relatively high BMS modal abundance of the four investigated xenoliths cannot be reconciled with the residual nature of these peridotites, but requires addition of metasomatic BMS. This is especially evident in the two peridotites with the highest bulk Pd/Ir and Pd/Pt. Metasomatic BMS likely formed during melt/fluid percolation in the Sub Continental Lithospheric Mantle (SCLM) as well as during infiltration of the host kimberlite magma, when djerfisherite crystallized around older Fe-Ni-sulfides. On the whole-rock scale, kimberlite metasomatism is visible in a subset of bulk xenoliths, which defines a Re-Os errorchron that dates the host magma emplacement. The 187Os/188Os measured in the twenty analysed BMS grains vary from 0.1084 to >0.17 and it shows no systematic variation depending on the sulfide mineralogical assemblage. The largest range in 187Os/188Os is observed in BMS grains from the two xenoliths with the highest Pd/Ir, Pd/Pt, and sulfide modal abundance. The whole-rock TRD ages of these two samples underestimate the melting age obtained from BMS, demonstrating that bulk Re-Os model ages from peridotites with clear evidence of metasomatism should be treated with caution. The TRD ages determined in BMS grains are clustered around 2.8-2.7, ∼2.2 and ∼1.9 Ga. The 2.8-2.7 Ga TRD ages document the main SCLM building event in the Rae craton, which is likely related to the formation of the local greenstone belts in a continental rift setting. The Paleoproterozoic TRD ages can be explained by

Comparison of HfCl4, HfI4, TEMA-Hf, and TDMA-Hf as precursors in early growing stages of HfO2 films deposited by ALD: A DFT study

International Nuclear Information System (INIS)

Cortez-Valadez, M.; Fierro, C.; Farias-Mancilla, J.R.; Vargas-Ortiz, A.; Flores-Acosta, M.; Ramírez-Bon, R.; Enriquez-Carrejo, J.L.

2016-01-01

Highlights: • Hafnium oxide growth on Si(100) by atomic layer deposition was simulated. • The interface structure was considered as silicate and silicide. • The interface was studied employing DFT. • TDMA-Hf precursor show better interface stability. - Abstract: The final structure of HfO 2 films grown by atomic layer deposition (ALD) after reaction with OH − ions has been analyzed by DFT (density functional theory). The interaction of the precursors: HfCl 4 (hafnium tetrachloride), HfI 4 (hafnium tetraiodide), TEMA-Hf (tetrakis-ethylmethylamino hafnium), and TDMA-Hf (tetrakis-dimethylamino hafnium) with HO–H was studied employing the B3LYP (Becke 3-parameter, Lee–Yang–Parr) hybrid functional and the PBE (Perdew–Burke–Ernzerhof) generalized gradient functional. The structural evolution at the Si(100) surface has been analyzed by LDA (local density approximation). The structural parameters: bond length and bond angle, and the vibrational parameters for the optimized structures are also reported. The presence of hafnium silicate at the interface was detected. The infrared spectra and structural parameters obtained in this work agree with previously reported experimental results.

O regime do recurso de agravo a partir das alteraçãoes introduzidas pela lei 11.187/2005

OpenAIRE

Ana Luiza Duarte Pires de Castro

2011-01-01

O direito processual civil é um ramo dinâmico do direito que busca ajustar-se às mudanças da sociedade e tem o fito de, pacificamente, solucionar os litígios que a ela se apresentam. Nesse norte, em virtude de estar sempre em busca de prestar uma tutela jurisdicional mais eficaz, o legislador pretendeu, através da edição da Lei 11.187/2005 - a qual disciplina o novo regime do recurso de agravo, dar maior celeridade processual. Para tanto, restringiu o uso do agravo de instrumento (caput do...

Synthesis and characterization of hafnium carbide microcrystal chains with a carbon-rich shell via CVD

International Nuclear Information System (INIS)

Tian, Song; Li, Hejun; Zhang, Yulei; Liu, Sen; Fu, Yangxi; Li, Yixian; Qiang, Xinfa

2013-01-01

Graphical abstract: Novel HfC microcrystal chains have been synthesized via a catalyst-assisted chemical vapor deposition process. SEM results show the chains have a periodically changing diameter and a nanoscale sharpening tip. Analysis of TEM/SAED/EELS/EDX data shows the single-crystal chains grow along a [0 0 1] direction and consist of a HfC core and a thin carbon-rich shell with embedded HfC nanocrystallites surrounding the core. This work achieves the controllable preparation of nanoscale HfC sharpening tips for application as a point electron emission source and facilitates the application of HfC ultrafast laser-triggered tips in attosecond science. Highlights: •HfC microcrystal chains were synthesized by a catalyst-assisted CVD. •The chains grow along a [0 0 1] direction and have a periodically changing diameter. •Single-crystal HfC core is sheathed by a thin carbon-rich shell. •A growth mechanism model is proposed to explain the growth of microcrystal chians. •This work achieves the controllable preparation of nanoscale HfC sharpening tips. -- Abstract: Novel hafnium carbide (HfC) microcrystal chains, with a periodically changing diameter and a nanoscale sharpening tip at the chain end, have been synthesized via a catalyst-assisted chemical vapor deposition (CVD) process. The as-synthesized chains with many octahedral microcrystals have diameters of between several hundreds of nm and 6 μm and lengths of ∼500 μm. TEM diffraction studies show that the chains are single-crystalline HfC and preferentially grow along a [0 0 1] crystal orientation. TEM/EELS/EDX analysis proves the chains are composed of a HfC core and a thin (several tens of nm to 100 nm) carbon-rich shell with the embedded HfC nanocrystallites (typically below 10 nm) surrounding the core. The growth mechanism model for the chains based on the vapor–liquid–solid process, the vapor–solid process, and the HfC crystal growth characteristics is discussed

Design of an Extractive Distillation Column for the Environmentally Benign Separation of Zirconium and Hafnium Tetrachloride for Nuclear Power Reactor Applications

Directory of Open Access Journals (Sweden)

Le Quang Minh

2015-09-01

Full Text Available Nuclear power with strengthened safety regulations continues to be used as an important resource in the world for managing atmospheric greenhouse gases and associated climate change. This study examined the environmentally benign separation of zirconium tetrachloride (ZrCl4 and hafnium tetrachloride (HfCl4 for nuclear power reactor applications through extractive distillation using a NaCl-KCl molten salt mixture. The vapor–liquid equilibrium behavior of ZrCl4 and HfCl4 over the molten salt system was correlated with Raoult’s law. The molten salt-based extractive distillation column was designed optimally using a rigorous commercial simulator for the feasible separation of ZrCl4 and HfCl4. The molten salt-based extractive distillation approach has many potential advantages for the commercial separation of ZrCl4 and HfCl4 compared to the conventional distillation because of its milder temperatures and pressure conditions, smaller number of required separation trays in the column, and lower energy requirement for separation, while still taking the advantage of environmentally benign feature by distillation. A heat-pump-assisted configuration was also explored to improve the energy efficiency of the extractive distillation process. The proposed enhanced configuration reduced the energy requirement drastically. Extractive distillation can be a promising option competing with the existing extraction-based separation process for zirconium purification for nuclear power reactor applications.

Cobalt(II), nickel(II), copper(II), zinc(II) and hafnium(IV) complexes of N'-(furan-3-ylmethylene)-2-(4-methoxyphenylamino)acetohydrazide.

Science.gov (United States)

Emam, Sanaa M; El-Saied, Fathy A; Abou El-Enein, Saeyda A; El-Shater, Heba A

2009-03-01

Cobalt(II), nickel(II), copper(II), zinc(II) and hafnium(IV) complexes of furan-2-carbaldehyde 4-methoxy-N-anilinoacetohydrazone were synthesized and characterized by elemental and thermal (TG and DTA) analyses, IR, UV-vis and (1)H NMR spectra as well as magnetic moment and molar conductivity. Mononuclear complexes are obtained with 1:1 molar ratio except complexes 3 and 9 which are obtained with 1:2 molar ratios. The IR spectra of ligand and metal complexes reveal various modes of chelation. The ligand behaves as a neutral bidentate one and coordination occurs via the carbonyl oxygen atom and azomethine nitrogen atom. The ligand behaves also as a monobasic tridentate one and coordination occurs through the enolic oxygen atom, azomethine nitrogen atom and the oxygen atom of furan ring. Moreover, the ligand behaves as a neutral tridentate and coordination occurs via the carbonyl oxygen, azomethine nitrogen and furan oxygen atoms as well as a monobasic bidentate and coordination occurs via the enolic oxygen atom and azomethine nitrogen atom. The electronic spectra and magnetic moment measurements reveal that all complexes possess octahedral geometry except the copper complex 10 possesses a square planar geometry. The thermal studies showed the type of water molecules involved in metal complexes as well as the thermal decomposition of some metal complexes.

Comparison of HfCl4, HfI4, TEMA-Hf, and TDMA-Hf as precursors in early growing stages of HfO2 films deposited by ALD: A DFT study

Science.gov (United States)

Cortez-Valadez, M.; Fierro, C.; Farias-Mancilla, J. R.; Vargas-Ortiz, A.; Flores-Acosta, M.; Ramírez-Bon, R.; Enriquez-Carrejo, J. L.; Soubervielle-Montalvo, C.; Mani-Gonzalez, P. G.

2016-06-01

The final structure of HfO2 films grown by atomic layer deposition (ALD) after reaction with OH- ions has been analyzed by DFT (density functional theory). The interaction of the precursors: HfCl4 (hafnium tetrachloride), HfI4 (hafnium tetraiodide), TEMA-Hf (tetrakis-ethylmethylamino hafnium), and TDMA-Hf (tetrakis-dimethylamino hafnium) with HO-H was studied employing the B3LYP (Becke 3-parameter, Lee-Yang-Parr) hybrid functional and the PBE (Perdew-Burke-Ernzerhof) generalized gradient functional. The structural evolution at the Si(100) surface has been analyzed by LDA (local density approximation). The structural parameters: bond length and bond angle, and the vibrational parameters for the optimized structures are also reported. The presence of hafnium silicate at the interface was detected. The infrared spectra and structural parameters obtained in this work agree with previously reported experimental results.

A spanish mineral of zirconium and hafnium. Separation of the two elements by liquid-liquid extraction, using tributyl phosphate as chelating agent; Beneficio de un mineral espanol de circonio-hafnio. Separacion de ambos elementos por extraccion liquido-liquido, empleando fosfato de tributilo como agente de quelacion

Energy Technology Data Exchange (ETDEWEB)

Ruiz Sanchez, F; Cruz Castillo, F. de la; Fernandez Cellini, R

1962-07-01

The zirconium and Hafnium oxides are obtained from a Spanish mineral of zircon with an average contest of 55% in ZrO{sub 2}-HfO{sub 2}. An alkaline fusion to open the mineral, followed by a purification by crystallization as (Zr O-Hf O)Cl{sub 2} H{sub 2}O or as (Zr-Hf) (SO{sub 4}){sub 2}. 4H{sub 2}O, is used. A discussion of the best experimental conditions for opening the mineral and of the purification method is made. (Author) 45 refs.

6-Peroxo-6-zirconium crown and its hafnium analogue embedded in a triangular polyanion: [M6(O2)6(OH)6(gamma-SiW10O36)3]18- (M = Zr, Hf).

Science.gov (United States)

Bassil, Bassem S; Mal, Sib Sankar; Dickman, Michael H; Kortz, Ulrich; Oelrich, Holger; Walder, Lorenz

2008-05-28

We have synthesized and structurally characterized the unprecedented peroxo-zirconium(IV) containing [Zr6(O2)6(OH)6(gamma-SiW10O36)3]18- (1). Polyanion 1 comprises a cyclic 6-peroxo-6-zirconium core stabilized by three decatungstosilicate units. We have also prepared the isostructural hafnium(IV) analogue [Hf6(O2)6(OH)6(gamma-SiW10O36)3]18- (2). We investigated the acid/base and redox properties of 1 by UV-vis spectroscopy and electrochemistry studies. Polyanion 1 represents the first structurally characterized Zr-peroxo POM with side-on, bridging peroxo units. The simple, one-pot synthesis of 1 and 2 involving dropwise addition of aqueous hydrogen peroxide could represent a general procedure for incorporating peroxo groups into a large variety of transition metal and lanthanide containing POMs.

Comparison of HfCl{sub 4}, HfI{sub 4}, TEMA-Hf, and TDMA-Hf as precursors in early growing stages of HfO{sub 2} films deposited by ALD: A DFT study

Energy Technology Data Exchange (ETDEWEB)

Cortez-Valadez, M. [Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-88, 83190 Hermosillo, Son. (Mexico); Fierro, C.; Farias-Mancilla, J.R. [Instituto de Ingeniería y Tecnología, Departamento de Física y Matemáticas, Universidad Autónoma de Ciudad Juárez, Av. del Charro 450, Cd. Juárez C.P. 32310, Chihuahua (Mexico); Vargas-Ortiz, A. [Universidad Autónoma de Sinaloa, Facultad de Ingeniería Mochis, Ciudad Universitaria, C.P. 81223 Los Mochis, Sinaloa (Mexico); Flores-Acosta, M. [Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-88, 83190 Hermosillo, Son. (Mexico); Ramírez-Bon, R. [Centro de Investigación y Estudios Avanzados del IPN, Unidad Querétaro, Apdo. Postal 1-798, 76001 Querétaro, Qro. (Mexico); Enriquez-Carrejo, J.L. [Instituto de Ingeniería y Tecnología, Departamento de Física y Matemáticas, Universidad Autónoma de Ciudad Juárez, Av. del Charro 450, Cd. Juárez C.P. 32310, Chihuahua (Mexico); and others

2016-06-15

Highlights: • Hafnium oxide growth on Si(100) by atomic layer deposition was simulated. • The interface structure was considered as silicate and silicide. • The interface was studied employing DFT. • TDMA-Hf precursor show better interface stability. - Abstract: The final structure of HfO{sub 2} films grown by atomic layer deposition (ALD) after reaction with OH{sup −} ions has been analyzed by DFT (density functional theory). The interaction of the precursors: HfCl{sub 4} (hafnium tetrachloride), HfI{sub 4} (hafnium tetraiodide), TEMA-Hf (tetrakis-ethylmethylamino hafnium), and TDMA-Hf (tetrakis-dimethylamino hafnium) with HO–H was studied employing the B3LYP (Becke 3-parameter, Lee–Yang–Parr) hybrid functional and the PBE (Perdew–Burke–Ernzerhof) generalized gradient functional. The structural evolution at the Si(100) surface has been analyzed by LDA (local density approximation). The structural parameters: bond length and bond angle, and the vibrational parameters for the optimized structures are also reported. The presence of hafnium silicate at the interface was detected. The infrared spectra and structural parameters obtained in this work agree with previously reported experimental results.

Multiple Sclerosis (M.S.: Epidemiologic Research in 187 Patients Who Admitted in University Cnters of Tehran in 1998

Directory of Open Access Journals (Sweden)

Homeira Sajjadi

2001-01-01

Full Text Available Objective: Multiple Sclerosis (M.S. is a chronic disease which most commonly involves females. Prevalence of disease begins from adolescent, gradually increases until 35 years old and then decreases. Its geographical distribution is non homogen and prevalence changes from 5/100000 to 250/100000. Iran is a low incident region with prevalence of 5/100000 or at least 3000 patients. Materials & Methods: This research has been done on 187 patients who admitted in Tehran university centers in 1998. Results: Results show that 63.3% of patients were female and most of them were married. The average age at beginning was 28y. Conclusion: Manifestation of disease were: Extremity weakness (44.2%, vision cloudiness and diplopia (33.7% and sensory disturbances (32.2%.

Neutron capture cross section measurements and theoretical calculation for the {sup 186}W(n,γ){sup 187}W reaction

Energy Technology Data Exchange (ETDEWEB)

Al-abyad, Mogahed; Mohamed, Gehan Y. [Atomic Energy Authority, Cairo (Egypt). Experimental Nuclear Physics Dept.

2017-08-01

Neutron capture cross section (σ{sub 0}) and resonance integral (I{sub 0}) of the reaction {sup 186}W(n,γ){sup 187}W were measured experimentally using the research reactor (ETRR-2) and an Am-Be neutron source, also calculated using TALYS-1.6 code. The present results of σ{sub 0} are (39.08±2.6, 38.75±0.98 and 38.33 barn) and I{sub 0} are (418.5±74, 439.3±36 and 445.5 barn) by using the reactor, neutron source and TALYS-1.6, respectively. The present results are in acceptable agreement with most of the previous experimental and evaluated data as well as the theoretical calculations.

[Erectile dysfunction and diabetes in Conakry (Guinea): frequency and clinical characteristics from 187 diabetic patients].

Science.gov (United States)

Baldé, N M; Diallo, A B; Baldé, M C; Kaké, A; Diallo, M M; Diallo, M B; Maugendre, D

2006-09-01

Sexual dysfunction is frequent in the diabetic population. In Africa, medical care for erectile dysfunction is underprovided, profoundly altering the quality of life of the patients. We report the prevalence of erectile dysfunction in 187 diabetic patients followed in the department of Endocrinology of the Conakry teaching hospital. Prevalence was estimated from the French version of the International Index of Erectile Function (IIEF). Erectile dysfunction concerned 90 patients (48%) of whom a severe form was observed in 54%, a moderate form in 35% and a mild form in 12%. The patients who presented erectile dysfunction were significantly older, displayed longer duration of diabetes with more complications (sensorial neuropathy and macroangiopathy) and often took drugs for associated cardiovascular diseases. In 28% of the cases, erectile dysfunction was associated with a decline in libido and in 26% with ejaculation disorders. In conclusion, erectile dysfunction is frequent and severe among diabetic patients in Guinea. The medical staff plays an essential role to initiate early diagnosis, promote psychological support and provide medication, if possible.

A 1:8.7 Scale Water Tunnel Verification & Validation Test of an Axial Flow Water Turbine

Energy Technology Data Exchange (ETDEWEB)

Fontaine, Arnold A. [Pennsylvania State Univ., University Park, PA (United States); Straka, William A. [Pennsylvania State Univ., University Park, PA (United States); Meyer, Richard S. [Pennsylvania State Univ., University Park, PA (United States); Jonson, Michael L. [Pennsylvania State Univ., University Park, PA (United States)

2014-09-01

As interest in waterpower technologies has increased over the last few years, there has been a growing need for a public database of measured data for these devices. This would provide a basic understanding of the technology and means to validate analytic and numerical models. Through collaboration between Sandia National Laboratories, Penn State University Applied Research Laboratory, and University of California, Davis, a new marine hydrokinetic turbine rotor was designed, fabricated at 1:8.7-scale, and experimentally tested to provide an open platform and dataset for further study and development. The water tunnel test of this three-bladed, horizontal-axis rotor recorded power production, blade loading, near-wake characterization, cavitation effects, and noise generation. This report documents the small-scale model test in detail and provides a brief discussion of the rotor design and an initial look at the results with comparison against low-order modeling tools. Detailed geometry and experimental measurements are released to Sandia National Laboratories as a data report addendum.

Muscle MRI in neutral lipid storage disease with myopathy carrying mutation c.187+1G>A.

Science.gov (United States)

Xu, Chunxiao; Zhao, Yawen; Liu, Jing; Zhang, Wei; Wang, Zhaoxia; Yuan, Yun

2015-06-01

We describe the clinical and muscle MRI changes in 2 siblings with neutral lipid storage disease with myopathy (NLSDM) carrying the mutation c.187+1G>A. Peripheral blood smears, genetic tests, and muscle biopsies were performed. Thigh MRI was performed to observe fatty replacement, muscle edema, and muscle bulk from axial sections. Both siblings had similar fatty infiltration and edema. T1-weighted images of the gluteus maximus, adductor magnus, semitendinosus, and semimembranosus revealed marked and diffuse fatty infiltration. There was asymmetric involvement in biceps femoris and quadriceps. There was extensive fatty infiltration in the quadriceps, except for the rectus femoris. Gracilis and sartorius were relatively spared. Thigh muscle volume was decreased, while the gracilis and sartorius appeared to show compensatory hypertrophy. Compared with previous reports in NLSDM, MRI changes in this myopathy tended to be more severe. Asymmetry and relatively selective fatty infiltration were characteristics. © 2014 Wiley Periodicals, Inc.

Corrosion resistant surface for vanadium nitride and hafnium nitride layers as function of grain size

Science.gov (United States)

Escobar, C. A.; Caicedo, J. C.; Aperador, W.

2014-01-01

In this research it was studied vanadium nitride (VN) and hafnium nitride (HfN) film, which were deposited onto silicon (Si (100)) and AISI 4140 steel substrates via r.f. magnetron sputtering technique in Ar/N2 atmosphere with purity at 99.99% for both V and Hf metallic targets. Both films were approximately 1.2±0.1 μm thick. The crystallography structures that were evaluated via X-ray diffraction analysis (XRD) showed preferential orientations in the Bragg planes VN (200) and HfN (111). The chemical compositions for both films were characterized by EDX. Atomic Force Microscopy (AFM) was used to study the morphology; the results reveal grain sizes of 78±2 nm for VN and 58±2 nm for HfN and roughness values of 4.2±0.1 nm for VN and 1.5±0.1 nm for HfN films. The electrochemical performance in VN and HfN films deposited onto steel 4140 were studied by Tafel polarization curves and impedance spectroscopy methods (EIS) under contact with sodium chloride at 3.5 wt% solution, therefore, it was found that the corrosion rate decreased about 95% in VN and 99% for HfN films in relation to uncoated 4140 steel, thus demonstrating, the protecting effect of VN and HfN films under a corrosive environment as function of morphological characteristics (grain size). VN(grain size)=78±2.0 nm, VN(roughness)=4.2±0.1 nm, VN(corrosion rate)=40.87 μmy. HfN(grain size)=58±2.0 nm, HfN(roughness)=1.5±0.1 nm, HfN(corrosion rate)=0.205 μmy. It was possible to analyze that films with larger grain size, can be observed smaller grain boundary thus generating a higher corrosion rate, therefore, in this work it was found that the HfN layer has better corrosion resistance (low corrosion rate) in relation to VN film which presents a larger grain size, indicating that the low grain boundary in (VN films) does not restrict movement of the Cl- ion and in this way the corrosion rate increases dramatically.

X-ray structure of imidazolonepropionase from Agrobacterium tumefaciens at 1.87 Å resolution

Energy Technology Data Exchange (ETDEWEB)

Tyagi, Rajiv; Kumaran, Desigan; Burley, Stephen K.; Swaminathan, Subramanyam (SGX); (BNL)

2010-01-12

Histidine degradation in Agrobacterium tumefaciens involves four enzymes, including histidase (EC 4.3.1.3), urocanase (EC 4.2.1.49), imidazolonepropionase (EC 3.5.2.7), and N-formylglutamate amidohydrolase (EC 3.5.3.8). The third enzyme of the pathway, imidazolone-propionase, a 45.6 kDa protein, catalyzes conversion of imidazolone-5-propanoate to N-forminio-L-glutamate. Initial studies of the role of imidazolonepropionase in histidine degradation were published in 1953. Subsequent publications have been limited to enzyme kinetics, crystallization, and a recently reported structure determination. The imidazolonepropionases are members of metallodepenent-hydrolases (or amidohydroase) superfamily, which includs ureases, adenosine deaminases, phosphotriesterases, dihydroorotases, allantoinases, hydantoinases, adenine and cytosine deaminases, imidazolonepropionases, aryldial-kylphosphatases, chlorohydrolases, and formylmethanofuran dehydroases. Proteins belonging to this large group share a common three-dimensional structural motif (an eightfold {alpha}/{beta} or TIM barrel) with similar active sites. Most superfamily members also share a conserved metal binding site, involving four histidine residues and one aspartic acid. Imidazolonepropionase is one of the targets selected for X-ray crystallpgrahpic structure determination by the New York Structural GenomiX Research Consortium (NYSGXRC) Target ID: 9252b to correlate the structure function relationship of poorly studied by important enzyme. Here they report the crystal structure of imidazolonepropionase from Agrobacterium tumefaciens determined at 1.87 {angstrom} resolution.

Spectroscopy of exotic nuclei with A {approx} 190: single particle states and collective properties of {sup 187,189}Bi and {sup 188}Pb; Spectroscopie de noyaux exotiques dans la region de masse A {approx} 190: la structure des isotopes {sup 187,189}Bi et {sup 188}Pb

Energy Technology Data Exchange (ETDEWEB)

Huerstel, A

2002-11-01

This thesis is devoted to the study of very neutron deficient nuclei in the lead region of the nuclear chart and more precisely to the investigation of the single particle states and collective properties of the {sup 187,189}Bi isotopes by gamma-ray spectroscopy. These nuclei were produced via fusion-evaporation reaction induced by a krypton beam on a silver target. In this mass region, the cross section for producing these nuclei are very low, of the order of a few micro-barns, making experimental studies very difficult. The identification of the nuclei was done using the very powerful RDT (Recoil Decay Tagging) technique, based on the selection of the isotopes through their characteristic alpha-particle decays. The experiments were performed at the university of Jyvdskyla (Finland) with the facility combining the gamma-ray spectrometer JUROSPHERE and the magnetic gas-filled separator RITU. Isomeric states were observed in both nuclei and their life-times measured. The systematics of individual proton states in odd-mass bismuth isotopes have been reproduced with a shell model up to 20 neutrons away from the valley of stability. Furthermore, rotational bands, a signature of collective nuclear motion, have been established for the first time in these nuclei. The interpretation of these results led to the conclusion that {sup 187,189}Bi have a prolate shape at low excitation energy, unlike the heavier bismuth isotopes which have been interpreted to have oblate deformation, implying a shape transition in this mass region. Hartree-Fock-Bogolyubov calculations are consistent with the experimental indication of shape coexistence, as seen in the neighbouring even-even lead nuclei. (author)

Technical Note: A simulation study on the feasibility of radiotherapy dose enhancement with calcium tungstate and hafnium oxide nano- and microparticles.

Science.gov (United States)

Sherck, Nicholas J; Won, You-Yeon

2017-12-01

To assess the radiotherapy dose enhancement (RDE) potential of calcium tungstate (CaWO 4 ) and hafnium oxide (HfO 2 ) nano- and microparticles (NPs). A Monte Carlo simulation study was conducted to gauge their respective RDE potentials relative to that of the broadly studied gold (Au) NP. The study was warranted due to the promising clinical and preclinical studies involving both CaWO 4 and HfO 2 NPs as RDE agents in the treatment of various types of cancers. The study provides a baseline RDE to which future experimental RDE trends can be compared to. All three materials were investigated in silico with the software Penetration and Energy Loss of Positrons and Electrons (PENELOPE 2014) developed by Francesc Salvat and distributed in the United States by the Radiation Safety Information Computational Center (RSICC) at Oak Ridge National Laboratory. The work utilizes the extensively studied Au NP as the "gold standard" for a baseline. The key metric used in the evaluation of the materials was the local dose enhancement factor (DEF loc ). An additional metric used, termed the relative enhancement ratio (RER), evaluates material performance at the same mass concentrations. The results of the study indicate that Au has the strongest RDE potential using the DEF loc metric. HfO 2 and CaWO 4 both underperformed relative to Au with lower DEF loc of 2-3 × and 4-100 ×, respectively. The computational investigation predicts the RDE performance ranking to be: Au > HfO 2 > CaWO 4 . © 2017 American Association of Physicists in Medicine.

G 126.1-0.8-14: A molecular shell related to Sh2-187

Science.gov (United States)

Cichowolski, S.; Pineault, S.; Gamen, R.; Ortega, M. E.; Arnal, E. M.; Suad, L. A.

2014-10-01

We present a multi-wavelength study of a region where a well defined molecular shell, named G 126.1-0.8-14, is observed. The distance of G 126.1-0.8-14 is about 1 kpc. Based on HI and CO data we analyze the atomic and molecular gas related to the structure and estimate its main physical properties. From the radio continuum and infrared data we analyze whether the emission associated with G 126.1-0.8-14 has a thermal origin. To disentangle the possible origin of the shell, and given the lack of catalogued O-type stars in the area, we observed with GEMINI the spectra of four OB stars located in projection inside the shell, to get their accurate spectral types and distances. The young HII region Sh2-187 is located onto the densest part of this molecular shell. A search for young stellar object candidates (cYSOs) was made using infrared point source catalogs. Several cYSOs are found spread out onto the shell. Based on all the available data, we discuss the possible origin of G 126.1-0.8-14 as well as its role in the formation of a new generation of stars.

Effect of Advanced Plasma Source bias voltage on properties of HfO2 films prepared by plasma ion assisted electron evaporation from metal hafnium

International Nuclear Information System (INIS)

Zhu, Meiping; Yi, Kui; Arhilger, Detlef; Qi, Hongji; Shao, Jianda

2013-01-01

HfO 2 films, using metal hafnium as starting material, are deposited by plasma-ion assisted electron evaporation with different Advanced Plasma Source (APS) bias voltages. The refractive index and extinction coefficient are calculated, the chemical state and composition, as well as the stress and aging behavior is investigated. Laser induced damage threshold (LIDT) and damage mechanism are also evaluated and discussed. Optical, structural, mechanical and laser induced damage properties of HfO 2 films are found to be sensitive to APS bias voltage. The film stress can be tuned by varying the APS bias voltage. Damage morphologies indicate the LIDT of the HfO 2 films at 1064 nm and 532 nm are dominated by the nodular-defect density in coatings, while the 355 nm LIDT is dominated by the film absorption. HfO 2 films with higher 1064 nm LIDT than samples evaporated from hafnia are achieved with bias voltage of 100 V. - Highlights: • HfO 2 films are evaporated with different Advanced Plasma Source (APS) bias voltages. • Properties of HfO 2 films are sensitive to APS bias voltage. • With a bias voltage of 100 V, HfO 2 coatings without any stress can be achieved. • Higher 1064 nm laser induced damage threshold is achieved at a bias voltage of 100 V

Impedance Characterization of the Capacitive field-Effect pH-Sensor Based on a thin-Layer Hafnium Oxide Formed by Atomic Layer Deposition

Directory of Open Access Journals (Sweden)

Michael LEE

2014-05-01

Full Text Available As a sensing element, silicon dioxide (SiO2 has been applied within ion-sensitive field effect transistors (ISFET. However, a requirement of increasing pH-sensitivity and stability has observed an increased number of insulating materials that obtain high-k gate being applied as FETs. The increased high-k gate reduces the required metal oxide layer and, thus, the fabrication of thin hafnium oxide (HfO2 layers by atomic layer deposition (ALD has grown with interest in recent years. This metal oxide presents advantageous characteristics that can be beneficial for the advancements within miniaturization of complementary metal oxide semiconductor (CMOS technology. In this article, we describe a process for fabrication of HfO2 based on ALD by applying water (H2O as the oxygen precursor. As a first, electrochemical impedance spectroscopy (EIS measurements were performed with varying pH (2-10 to demonstrate the sensitivity of HfO2 as a potential pH sensing material. The Nyquist plot demonstrates a high clear shift of the polarization resistance (Rp between pH 6-10 (R2 = 0.9986, Y = 3,054X + 12,100. At acidic conditions (between pH 2-10, the Rp change was small due to the unmodified oxide gate (R2 = 0.9655, Y = 2,104X + 4,250. These preliminary results demonstrate the HfO2 substrate functioned within basic to neutral conditions and establishes a great potential for applying HfO2 as a dielectric material for future pH measuring FET sensors.

A silicon doped hafnium oxide ferroelectric p–n–p–n SOI tunneling field–effect transistor with steep subthreshold slope and high switching state current ratio

Directory of Open Access Journals (Sweden)

Saeid Marjani

2016-09-01

Full Text Available In this paper, a silicon–on–insulator (SOI p–n–p–n tunneling field–effect transistor (TFET with a silicon doped hafnium oxide (Si:HfO2 ferroelectric gate stack is proposed and investigated via 2D device simulation with a calibrated nonlocal band–to–band tunneling model. Utilization of Si:HfO2 instead of conventional perovskite ferroelectrics such as lead zirconium titanate (PbZrTiO3 and strontium bismuth tantalate (SrBi2Ta2O9 provides compatibility to the CMOS process as well as improved device scalability. By using Si:HfO2 ferroelectric gate stack, the applied gate voltage is effectively amplified that causes increased electric field at the tunneling junction and reduced tunneling barrier width. Compared with the conventional p–n–p–n SOI TFET, the on–state current and switching state current ratio are appreciably increased; and the average subthreshold slope (SS is effectively reduced. The simulation results of Si:HfO2 ferroelectric p–n–p–n SOI TFET show significant improvement in transconductance (∼9.8X enhancement at high overdrive voltage and average subthreshold slope (∼35% enhancement over nine decades of drain current at room temperature, indicating that this device is a promising candidate to strengthen the performance of p–n–p–n and conventional TFET for a switching performance.

Synergistic effect of carbon nanotube as sintering aid and toughening agent in spark plasma sintered molybdenum disilicide-hafnium carbide composite

Energy Technology Data Exchange (ETDEWEB)

Mukherjee, Biswajyoti; Asiq Rahman, O.S.; Sribalaji, M [Materials Science and Engineering, Indian Institute of Technology Patna, Bihta Kanpa Road, Bihta, Patna, Bihar 801103 (India); Bakshi, Srinivasa Rao [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Keshri, Anup Kumar, E-mail: anup@iitp.ac.in [Materials Science and Engineering, Indian Institute of Technology Patna, Bihta Kanpa Road, Bihta, Patna, Bihar 801103 (India)

2016-12-15

Hafnium carbide (HfC) along with sintering aids was consolidated at a relatively lower temperature i.e. 1600 °C (i.e. T=~0.41 T{sub m}) under a uniaxial load of 50 MPa by spark plasma sintering. Two different sintering aids such as molybdenum disilicide (MoSi{sub 2}) and carbon nanotube (CNT) were added to enhance the densification and lower the extent of grain growth in the sintered pellets. Density of the sintered pellet increased from 96.0±0.8% in HfC +5 wt% MoSi{sub 2} (HM) to 99.0±0.5% with the addition of 2 wt% CNT in HfC+5 wt% MoSi{sub 2} (HMC) at sintering temperature of 1600 °C. Further, the extent of grain growth drastically reduced from 204% in HM to 50% in HMC. Analysis of linear shrinkage during densification revealed that CNT addition increased densification rate and decreased the time required to reach the density of 99.0±0.5% at 1600 °C. Increased densification and lower degree of grain growth could be due to the synergistic effect offered by the CNT, which are as follows: (i) Lubrication effect of CNT, (ii) Lower activation energy for grain boundary diffusion (iii) Reduction in liquid phase sintering temperature and (iv) Grain boundary pinning. Fracture toughness of the sintered HM and HMC composite was obtained using indentation technique. By the addition of 2 wt% CNT in HM, drastic increase of 91% in fracture toughness was seen. This significant improvement in fracture toughness was due to the enhanced densification and relatively lower grain size of HMC. Also crack bridging, crack deflection, crack arrest, CNT and graphene sheet pull-out and swording played major role in toughening of HMC pellet.

X-ray tube targets

International Nuclear Information System (INIS)

Hirsch, H.H.

1980-01-01

In rotary targets for X-ray tubes warping is a problem which causes X-ray deficiency. A rotary target is described in which warping is reduced by using alloys of molybdenum with 0.05 to 10% iron, silicon, cobalt, tantalum, niobium, hafnium, stable metal oxide or mixture thereof. Suitable mixtures are 0.5 to 10% of tantalum, niobium or hafnium with from 0.5 to 5% yttrium oxide, or 0.05 to 0.3% of cobalt or silicon. Optionally 0.1 to 5% by weight of additional material may be alloyed with the molybdenum, such as tantalum or hafnium carbides. (author)

40 CFR 421.332 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Science.gov (United States)

2010-07-01

... times. (d) SiCl4 purification wet air pollution control. BPT Limitations for the Primary Zirconium and...) Sand drying wet air pollution control. BPT Limitations for the Primary Zirconium and Hafnium... chlorination off-gas wet air pollution control. BPT Limitations for the Primary Zirconium and Hafnium...

Electrochemical-metallothermic reduction of zirconium in molten salt solutions

International Nuclear Information System (INIS)

McLaughlin, D.F.; Talko, F.

1990-01-01

This patent describes a method for separating hafnium from zirconium of the type wherein a feed containing zirconium and hafnium chlorides is prepared from zirconium-hafnium chloride and the feed is introduced into a distillation column, which distillation column has a reboiler connected at the bottom and a reflux condenser connected at the top and wherein a hafnium chloride enriched stream is taken from the top of the column and a zirconium enriched chloride stream is taken from the bottom of the column. It comprises: reducing the zirconium enriched chloride stream taken from the distillation column to metal by electrochemically reducing an alkaline earth metal in a molten salt bath with the molten salt in the molten salt bath consisting essentially of a mixture of at least one alkali metal chloride and at least one alkaline earth metal chloride and zirconium chloride, with the reduced alkaline earth metal reacting with the zirconium chloride to produce zirconium metal and alkaline earth metal chloride

Determination of hafnium at the 10−4% level (relative to zirconium content) using neutron activation analysis, inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectrometry

International Nuclear Information System (INIS)

Smolik, Marek; Polkowska-Motrenko, Halina; Hubicki, Zbigniew; Jakóbik-Kolon, Agata; Danko, Bożena

2014-01-01

Graphical abstract: -- Highlights: •We worked out ICP-MS method of Hf determination in Zr and Zr compounds. •We used NAA method as reference one. •We obtained pure zirconium matrix by ion exchange (Diphonix ® resin). •These permit to determine ≥1 × 10 −4 % Hf in Zr sample by ICP MS with good precision and accuracy. -- Abstract: Hafnium at the very low level of 1–8 ppm (in relation to zirconium) was determined in zirconium sulfate solutions (originating from investigations of the separation of ca. 44 ppm Hf from zirconium by means of the ion exchange method) by using three independent methods: inductively coupled plasma mass spectrometry (ICP MS), neutron activation analysis (NAA) and inductively coupled plasma atomic emission spectrometry (ICP-AES). The results of NAA and ICP MS determinations were consistent with each other across the entire investigated range (the RSD of both methods did not exceed 38%). The results of ICP-AES determination were more diverse, particularly at less than 5 ppm Hf (RSD was significantly higher: 29–253%). The ion exchange method exploiting Diphonix ® resin proved sufficient efficiency in Zr–Hf separation when the initial concentration ratio of the elements ([Zr] 0 /[Hf] 0 ) ranged from 1200 to ca. 143,000

Perturbed angular correlation

International Nuclear Information System (INIS)

Fabris, J.D.

1977-01-01

The electric quadrupolar interaction in some hafnium complexes, measured at the metal nucleus level is studied. For that purpose, the technique of γ-γ perturbed angular correlation is used: the frequencies of quadrupolar interaction are compared with some hafnium α-hydroxicarboxilates, namely glycolate, lactate, mandelate and benzylate; the influence of the temperature on the quadrupolar coupling on the hafnium tetramandelate is studied; finally, the effects associated with the capture of thermal neutrons by hafnium tetramandelate are examined locally at the nuclear level. The first group of results shows significant differences in a series of complexes derived from glycolic acid. On the other hand, the substitution of the protons in hafnium tetramandelate structure by some alkaline cations permits to verify a correlation between the variations in the quadrupolar coupling and the electronegativities of the substituent elements. Measurements at high temperatures show that this complex is thermally stable at 100 and 150 0 C. It is possible to see the appearance of two distinct sites for the probe nucleus, after heating the sample at 100 0 C for prolonged time. This fact is attributed to a probable interconversion among the postulated structural isomers for the octacoordinated compounds. Finally, measurements of angular correlation on the irradiated complex show that there is an effective destruction of the target molecule by neutron capture [pt

Use of the on-line Moessbauer effect as a contribution to the study of recoil defects in solids

International Nuclear Information System (INIS)

Jeandey, Christian

1974-01-01

This research thesis addresses the study of effects of nuclear reactions, also known as 'after-effects' such as atomic disorders resulted from atom recoil, but also possible chemical modifications. The author more particularly focuses of recoil defects. He reports a critical review of studies of structure defects (in pure metals, ordered alloys, ionic crystals) performed by using conventional resonance absorption, and then presents an analysis of results of the defect creation dynamics as it had been proposed by other authors. He also proposes an overview of the evolution and disappearance of defects during thermal treatments. After a review of experiments based on the on-line Moessbauer effect, the author reports the study of recoil effects in pure metals (iron, hafnium), in alloys (Fe 1-x Al x , FeGe 2 , cubic, monoclinic and hexagonal FeGe), and in organic complexes (ferrous oxalate, different types of hafnium chelate, hafnium oxide). He finally discusses the electronic properties of different types of iron and hafnium chelate in solid phase [fr

Grindability of cast Ti-Hf alloys.

Science.gov (United States)

Kikuchi, Masafumi; Takahashi, Masatoshi; Sato, Hideki; Okuno, Osamu; Nunn, Martha E; Okabe, Toru

2006-04-01

As part of our systematic studies characterizing the properties of titanium alloys, we investigated the grindability of a series of cast Ti-Hf alloys. Alloy buttons with hafnium concentrations up to 40 mass% were made using an argon-arc melting furnace. Each button was cast into a magnesia-based mold using a dental titanium casting machine; three specimens were made for each metal. Prior to testing, the hardened surface layer was removed. The specimens were ground at five different speeds for 1 min at 0.98 N using a carborundum wheel on an electric dental handpiece. Grindability was evaluated as the volume of metal removed per minute (grinding rate) and the volume ratio of metal removed compared to the wheel material lost (grinding ratio). The data were analyzed using ANOVA. A trend of increasing grindability was found with increasing amounts of hafnium, although there was no statistical difference in the grindability with increasing hafnium contents. We also found that hafnium may be used to harden or strengthen titanium without deteriorating the grindability.

Radioisotopic heat source

Science.gov (United States)

Jones, G.J.; Selle, J.E.; Teaney, P.E.

1975-09-30

Disclosed is a radioisotopic heat source and method for a long life electrical generator. The source includes plutonium dioxide shards and yttrium or hafnium in a container of tantalum-tungsten-hafnium alloy, all being in a nickel alloy outer container, and subjected to heat treatment of from about 1570$sup 0$F to about 1720$sup 0$F for about one h. (auth)

High-spin nuclear target of 178m2Hf: creation and nuclear reaction studies

International Nuclear Information System (INIS)

Oganessyan, Yu.Ts.; Karamyan, S.A.; Gangrskij, Yu.P.

1993-01-01

A long-lived (31 years) four-quasiparticle isomer 178m 2 Hf(I,K π =16,16 + ) was produced in microweight quantities using the nuclear reaction 176 Yb( 4 He, 2n). Methods of precision chemistry and mass-separation for the purification of the produced Hf material have been developed. Thin targets of isomeric hafnium-178 on carbon backings were prepared and used in experiments on a neutron, proton and deuteron beams. First results on nuclear reactions on a high-spin exotic target were obtained. Experiments on electromagnetic interactions of the isomeric hafnium using methods of the collinear laser spectroscopy as well as of the nuclear orientation of hafnium implanted into a crystalline media were started. 11 refs.; 11 figs.; 2 tabs

New type of colour reactions of o,o'-dihydroxyazo compounds

International Nuclear Information System (INIS)

Dedkov, Yu.M.; Podvigina, T.I.

1977-01-01

It is shown that in the system: zirconium (hafnium)-picramine-epsilon (PE)-ethylrhodamine S (ERS), a heteroligand complex is formed, with an excess of the organic reagents, having the following ratio of components: Zr(Hf):PE:ERS=1:2:5. The molecules of ERS substitute the protons of free OH groups in binary complexes of zirconium (hafnium) with PE, while the excess molecules of ERS are added associatively. The resulting complex is floated off, the flotation product is dissolved in acetone, and its optical density is measured. The true molar extinction coefficient of the complex is equal to 6x10 5 , while the apparent one equals 3.2x10 5 . It is possible to determine submicroamounts of zirconium (hafnium) with preminary Ti and Nb masking

Evolution of E 2 transition strength in deformed hafnium isotopes from new measurements on 172Hf,174Hf, and 176Hf

Science.gov (United States)

Rudigier, M.; Nomura, K.; Dannhoff, M.; Gerst, R.-B.; Jolie, J.; Saed-Samii, N.; Stegemann, S.; Régis, J.-M.; Robledo, L. M.; Rodríguez-Guzmán, R.; Blazhev, A.; Fransen, Ch.; Warr, N.; Zell, K. O.

2015-04-01

Background: The available data for E 2 transition strengths in the region between neutron-deficient hafnium and platinum isotopes are far from complete. More and precise data are needed to enhance the picture of structure evolution in this region and to test state-of-the-art nuclear models. In a simple model, the maximum collectivity is expected at the middle of the major shell. However, for actual nuclei, particularly in heavy-mass regions, which should be highly complex, this picture may no longer be the case, and one should use a more realistic nuclear-structure model. We address this point by studying the spectroscopy of Hf as a representative case. Purpose: We remeasure the 21+ half-lives of 172,174,176Hf, for which there is some disagreement in the literature. The main goal is to measure, for the first time, the half-lives of higher-lying states of the rotational band. The new results are compared to a theoretical calculation for absolute transition strengths. Method: The half-lives were measured using γ -γ and conversion-electron-γ delayed coincidences with the fast timing method. For the determination of half-lives in the picosecond region, the generalized centroid difference method was applied. For the theoretical calculation of the spectroscopic properties, the interacting boson model is employed, whose Hamiltonian is determined based on microscopic energy-density functional calculations. Results: The measured 21+ half-lives disagree with results from earlier γ -γ fast timing measurements, but are in agreement with data from Coulomb excitation experiments and other methods. Half-lives of the 41+ and 61+ states were measured, as well as a lower limit for the 81+ states. Conclusions: This work shows the importance of a mass-dependent effective boson charge in the interacting boson model for the description of E 2 transition rates in chains of nuclei. It encourages further studies of the microscopic origin of this mass dependence. New experimental

Ceramic material suitable for repair of a space vehicle component in a microgravity and vacuum environment, method of making same, and method of repairing a space vehicle component

Science.gov (United States)

Riedell, James A. (Inventor); Easler, Timothy E. (Inventor)

2009-01-01

A precursor of a ceramic adhesive suitable for use in a vacuum, thermal, and microgravity environment. The precursor of the ceramic adhesive includes a silicon-based, preceramic polymer and at least one ceramic powder selected from the group consisting of aluminum oxide, aluminum nitride, boron carbide, boron oxide, boron nitride, hafnium boride, hafnium carbide, hafnium oxide, lithium aluminate, molybdenum silicide, niobium carbide, niobium nitride, silicon boride, silicon carbide, silicon oxide, silicon nitride, tin oxide, tantalum boride, tantalum carbide, tantalum oxide, tantalum nitride, titanium boride, titanium carbide, titanium oxide, titanium nitride, yttrium oxide, zirconium diboride, zirconium carbide, zirconium oxide, and zirconium silicate. Methods of forming the ceramic adhesive and of repairing a substrate in a vacuum and microgravity environment are also disclosed, as is a substrate repaired with the ceramic adhesive.

Neutron cross section measurements using the ORELA: 40Ar(n,x), 40Ca(n,x), 22Ne(n,γ), 187Os(n,n') 186187188Os(n,nn'γ), the stable tellurium isotopes (n,γ), and 205Tl(n,nγ). Progress report, September 1, 1982-August 31, 1983

International Nuclear Information System (INIS)

Winters, R.R.

1983-09-01

The research performed during this reporting period consisted primarily of (1) measurement, analysis, and publication of the 187 Os(n,n') cross section near 30 keV, (2) measurement and analysis of the 148 149 159 Sm(n,γ) cross sections, (3) development and publication of a significantly better approximation to the average neutron scattering function as determined by total cross section measurements at the Oak Ridge Electron Linear Accelerator (ORELA), and (4) providing support for the neutron capture facility at ORELA as in the corrections made to the 60 Ni(n,γ) data discussed in a paper included with this report. The major result of the 187 Os(n,n') cross section measurement was the 30 keV average value for that cross section anti sigma/sub nn'/ approx. = 1.5 +- 0.2 b and the implication that the duration of stellar nucleosynthesis, as derived from the 187 Re → 187 Os beta decay, is estimated to be (8.9 +- 2.0) x 10 9 year consistent with an earlier estimate reported by Winters and Macklin. The Sm(n,γ) measurement has already resulted in an estimate of the importance of branching in the s-process in the samarium mass region. We estimate the average neutron density during s-process nucleosynthesis in the vicinity of the solar system to be between less than or equal to (1.1 + 0.7) and (1.1 - 0.6) x 10 8 neutrons/cm 3 . In the optical model analysis of neutron total cross sections we continue to find that orbital angular momentum dependent well depths are required if the spherical optical model is used to describe the neutron-nucleus interaction at low neutron energies

Proton and O sup(2-) ion diffusion studied by γ-γ angular correlation and by impedance spectroscopy

International Nuclear Information System (INIS)

Oliveira Damasceno, O. de.

1988-01-01

The interaction of sup(181) Ta quadrupole momentum with electric field gradient was measured by perturbed angular correlation spectroscopy in polycrystalline samples of hafnium hydride and hafnium oxide. The measurements were done as function of the temperature, in cubic and tetragonal phases of hafnium hydride. In the cubic phase, spin relaxation effects related to proton diffusion with activation energy of 0.43 ± 0.05eV were observed, and in the tetragonal phase, the interaction was purely static. The hafnium oxide was studied in cubic phase stabilized by addition of calcium oxide or magnesium oxide. Relaxation effects probably due to O sup(2-) ion diffusion were verified. The protonic conduction in K H sub(2) PO sub(4) was studied by impedance spectroscopy, in pellets prepared by melting or powder compression using silver and platinum electrodes. In the case of silver electrodes, in the low frequency region, the impedance spectrum tends to a 45 sup(0) typical line of the diffusion process. It was attributed to hydrogen injection in the electrode. Heating k H sub(2) PO sub(4) at about 230 sup(0)C modifies significantly the electric properties. Two relaxation annealing reduced conductivities to constant values independently of preparation method. (author)

Lowering the environmental impact of high-kappa/ metal gate stack surface preparation processes

Science.gov (United States)

Zamani, Davoud

ABSTRACT Hafnium based oxides and silicates are promising high-κ dielectrics to replace SiO2 as gate material for state-of-the-art semiconductor devices. However, integrating these new high-κ materials into the existing complementary metal-oxide semiconductor (CMOS) process remains a challenge. One particular area of concern is the use of large amounts of HF during wet etching of hafnium based oxides and silicates. The patterning of thin films of these materials is accomplished by wet etching in HF solutions. The use of HF allows dissolution of hafnium as an anionic fluoride complex. Etch selectivity with respect to SiO2 is achieved by appropriately diluting the solutions and using slightly elevated temperatures. From an ESH point of view, it would be beneficial to develop methods which would lower the use of HF. The first objective of this study is to find new chemistries and developments of new wet etch methods to reduce fluoride consumption during wet etching of hafnium based high-κ materials. Another related issue with major environmental impact is the usage of large amounts of rinsing water for removal of HF in post-etch cleaning step. Both of these require a better understanding of the HF interaction with the high-κ surface during the etching, cleaning, and rinsing processes. During the rinse, the cleaning chemical is removed from the wafers. Ensuring optimal resource usage and cycle time during the rinse requires a sound understanding and quantitative description of the transport effects that dominate the removal rate of the cleaning chemicals from the surfaces. Multiple processes, such as desorption and re-adsorption, diffusion, migration and convection, all factor into the removal rate of the cleaning chemical during the rinse. Any of these processes can be the removal rate limiting process, the bottleneck of the rinse. In fact, the process limiting the removal rate generally changes as the rinse progresses, offering the opportunity to save resources

Solvent extraction columns

International Nuclear Information System (INIS)

Middleton, P.; Smith, J.R.

1979-01-01

In pulsed columns for use in solvent extraction processes, e.g. the reprocessing of nuclear fuel, the horizontal perforated plates inside the column are separated by interplate spacers manufactured from metallic neutron absorbing material. The spacer may be in the form of a spiral or concentric circles separated by radial limbs, or may be of egg-box construction. Suitable neutron absorbing materials include stainless steel containing boron or gadolinium, hafnium metal or alloys of hafnium. (UK)

[Analysis of clinical characteristics of 187 patients with Marjolin's ulcers].

Science.gov (United States)

Liu, Zan; Zhou, Yuxiang; Zhang, Pihong; Zhang, Minghua; Ren, Licheng; Zeng, Jizhang; Zhou, Jie; Liang, Pengfei; Huang, Xiaoyuan

2016-05-01

To analyze the etiology and clinical characteristics of Marjolin's ulcer, and to explore its prevention and treatment. Medical records of 187 patients with Marjolin's ulcers admitted to the Department of Burns and Reconstructive Surgery of Xiangya Hospital of Central South University from January 1998 to May 2015 were retrospectively analyzed, including gender, age of onset of initial injury or primary disease, age of onset of Marjolin's ulcer, initial injury or primary disease, length of latency, lengths of pre- and post-ulceration periods, lesion site, lesion type, lesion area, local scar tension, histopathological type, degree of carcinoma cell differentiation, bone invasion and lymphadenopathy, treatment, and prognosis. The relationships between the age of onset of initial injury or primary disease and the length of latency, and the length of pre-ulceration period and the length of post-ulceration period were assessed by Spearman correlation analysis. The recurrence rates were processed with Fisher's exact test. (1) Among the patients, the ratio of male to female was nearly 1.6:1.0. The age of onset of initial injury or primary disease was 0.17-78.00 (17±18) years, and the age of onset of Marjolin's ulcers was 18-84 (49±14) years. (2) The most common initial injury among the patients was flame burn. The length of latency was 0.25-74.00 (32±16) years, and the lengths of pre- and post-ulceration periods were 0-73.00 (26±19) years and 0.08-59.00 (6±11) years respectively. The common lesion sites were the lower limbs and head and face. The rodent ulcer was the most common lesion type, and the lesion area was 1-625 (69±110) cm(2). There were obviously negative correlations between the age of onset of initial injury or primary disease and the length of latency, as well as the length of pre-ulceration period and the length of post-ulceration period (with r values respectively -0.71 and -0.50, P values below 0.01). The pathological scars of strong tension around

Combined effects of NQO1 Pro187Ser or SULT1A1 Arg213His polymorphism and smoking on bladder cancer risk: Two meta-analyses.

Science.gov (United States)

Wang, Xiao-Chun; Wang, Jian; Tao, Hui-Hui; Zhang, Chao; Xu, Li-Fa

2017-07-14

Objectives: Cigarette smoking is the major risk factor of bladder cancer via exposure to chemical carcinogens. Nicotinamide adenine dinucleotide phosphate (NADP+): quinine oxidoreductase 1 (NQO1) and sulfotransferase 1A1 (SULT1A1) have been reported to involve in the metabolism of polycyclic aromatic hydrocarbons (PAHs) and aromatic amines. Therefore, the risk of bladder cancer (BC) may be influenced by polymorphisms in the genes that modulate metabolic detoxification in particular by interacting with cigarette smoking. Considering the limited power by the individual studies with a relatively small sample size, especially when analyzing the combined effect of polymorphisms in NQO1 and SULT1A1 genes and smoking, these 2 meta-analyses have aimed to clarify the combined effects of them on BC risk by integrating related studies. Two meta-analyses included 1341 cases and 1346 controls concerning NQO1 Pro187Ser and smoking, and 1921 cases and 1882 controls on SULT1A1 Arg213His and smoking were performed. Odds ratios (OR) and 95% confidence intervals (CI) were used for assessing the strength of the association. The result has demonstrated that smokers with NQO1 Pro/Ser or Ser/Ser genotypes have a prominent association with the risk of BC as compared with non-smokers with NQO1 Pro/Pro genotype, with OR equal to 3.71 (95% CI: 2.87-4.78, pheterogeneity = 0.376). Besides, smokers carrying SULT1A1 Arg/Arg genotypes were observed to confer 2.38 fold increased risk of BC (95% CI: 1.44-3.93, pheterogeneity = 0.001) when compared with non-smokers with SULT1A1 Arg/Arg or His/His genotypes. These findings have suggested that the NQO1 Pro187Ser or SULT1A1 Arg213His polymorphism combination with smoking significantly confer susceptibility to BC. Int J Occup Med Environ Health 2017;30(5):791-802. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Combined effects of NQO1 Pro187Ser or SULT1A1 Arg213His polymorphism and smoking on bladder cancer risk: Two meta-analyses

Directory of Open Access Journals (Sweden)

Xiao-Chun Wang

2017-10-01

Full Text Available Objectives: Objectives: Cigarette smoking is the major risk factor of bladder cancer via exposure to chemical carcinogens. Nicotinamide adenine dinucleotide phosphate (NADP+: quinine oxidoreductase 1 (NQO1 and sulfotransferase 1A1 (SULT1A1 have been reported to involve in the metabolism of polycyclic aromatic hydrocarbons (PAHs and aromatic amines. Therefore, the risk of bladder cancer (BC may be influenced by polymorphisms in the genes that modulate metabolic detoxification in particular by interacting with cigarette smoking. Considering the limited power by the individual studies with a relatively small sample size, especially when analyzing the combined effect of polymorphisms in NQO1 and SULT1A1 genes and smoking, these 2 meta-analyses have aimed to clarify the combined effects of them on BC risk by integrating related studies. Material and Methods: Two meta-analyses included 1341 cases and 1346 controls concerning NQO1 Pro187Ser and smoking, and 1921 cases and 1882 controls on SULT1A1 Arg213His and smoking were performed. Odds ratios (OR and 95% confidence intervals (CI were used for assessing the strength of the association. Results: The result has demonstrated that smokers with NQO1 Pro/Ser or Ser/Ser genotypes have a prominent association with the risk of BC as compared with non-smokers with NQO1 Pro/Pro genotype, with OR equal to 3.71 (95% CI: 2.87–4.78, pheterogeneity = 0.376. Besides, smokers carrying SULT1A1 Arg/Arg genotypes were observed to confer 2.38 fold increased risk of BC (95% CI: 1.44–3.93, pheterogeneity = 0.001 when compared with non-smokers with SULT1A1 Arg/Arg or His/His genotypes. Conclusions: These findings have suggested that the NQO1 Pro187Ser or SULT1A1 Arg213His polymorphism combination with smoking significantly confer susceptibility to BC. Int J Occup Med Environ Health 2017;30(5:791–802

High-resolution metallic magnetic calorimeters for β-spectroscopy on 187rhenium and position resolved X-ray spectroscopy

International Nuclear Information System (INIS)

Porst, Jan-Patrick

2011-01-01

This thesis describes the development of metallic magnetic calorimeters (MMCs) for high resolution spectroscopy. MMCs are energy dispersive particle detectors based on the calorimetric principle which are typically operated at temperatures below 100 mK. The detectors make use of a paramagnetic temperature sensor to transform the temperature rise upon the absorption of a particle in the detector into a measurable magnetic flux change in a dc-SQUID. The application of MMCs for neutrino mass measurements and their advantages with respect to other approaches are discussed. In view of this application the development of an MMC optimized for β-endpoint spectroscopy on 187 rhenium is presented. A fully micro-fabricated X-ray detector is characterized and performs close to design values. Furthermore, a new technique to more efficiently couple rhenium absorbers mechanically and thermally to the sensor was developed and successfully tested. By employing a metallic contact, signal rise times faster than 5 μs could be observed with superconducting rhenium absorbers. In addition to the single pixel detectors, an alternative approach of reading out multiple pixels was developed in this work, too. Here, the individual absorbers have a different thermal coupling to only one temperature sensor resulting in a distribution of different pulse shapes. Straightforward position discrimination by means of rise time analysis is demonstrated for a four pixel MMC and a thermal model of the detector is provided. Unprecedented so far, an energy resolution of less than ΔE FWHM <5 eV for 5.9 keV X-rays was achieved across all absorbers. (orig.)

Cobalt catalysts for the conversion of methanol and for Fischer-tropsch synthesis to produce hydrocarbons

International Nuclear Information System (INIS)

Mauldin, C.H.; Davis, S.M.; Arcuri, K.B.

1987-01-01

A regeneration stable catalyst is described for the conversion at reaction conditions of methanol or synthesis gas to liquid hydrocarbons which consists essentially of from about 2 percent to about 25 percent cobalt, based on the weight of the catalyst composition, composited with titania, or a titania-containing support, to which is added sufficient of a zirconium, hafnium, cerium, or uranium promoter to provide a weight ratio of the zirconium, hafnium, cerium, or uranium metal:cobalt greater than about 0.101:1

Application of energy-dispersive XRF technique in the hydrometallurgy study of local zircon

International Nuclear Information System (INIS)

Meor Yusoff Sulaiman; Kamaruddin Hussin; Azizan Aziz

1996-01-01

In this study, energy-dispersive X-ray Fluorescence (EDXR-F) was used to analyse the elemental composition of the starting zircon mineral associated elements in the leaching solution. Besides analysing the major elements i.e. of zirconium, silicon and hafnium, trace elemental analysis for iron, titanium and the naturally occurring radioactive element thorium and uranium are important in establishing the grades of Malaysian zircon. The technique was also used in determine the optimum conditions for zirconium and hafnium recovery during the leaching process

Reactive evaporation of low-defect density hafnia

International Nuclear Information System (INIS)

Chow, R.; Falabella, S.; Loomis, G.E.; Rainer, F.; Stolz, C.J.; Kozlowski, M.R.

1993-01-01

Motivation for this work includes observations at Lawrence Livermore National Laboratory of a correlation between laser damage thresholds and both the absorption and the nodular-defect density of coatings. Activated oxygen is used to increase the metal-oxidation kinetics at the coated surface during electron-beam deposition. A series of hafnia layers are made with various conditions: two μ-wave configuations, two sources (hafnium and hafnia), and two reactive oxygen pressures. Laser damage thresholds (1064-nm, 10-ns pulses), absorption (at 511 nm), and nodular-defect densities from these coatings are reported. The damage thresholds are observed to increase as the absorption of the coatings decreases. However, no significant increase in damage thresholds are observed with the coatings made from a low nodular-defect density source material (hafnium). Hafnia coatings can be made from hafnium sources that have lower nodular-defect densities, lower absorption, and damage thresholds that are comparable with coatings made from a conventional hafnia source

Study of N-cinnamoylphenylhydroxylaminate solubility in water and organic solvents

International Nuclear Information System (INIS)

Pilipenko, A.T.; Shpak, Eh.A.; Samchuk, A.I.

1975-01-01

The composition of complexes of N-cinnamoylphenylhydroxylamine with copper, cadmium, lead, indium, iron, gallium, titanium, zirconium, hafnium, niobium, tantalum, tungsten, molybdenum and vanadium was determined. The solubility products of the N-cinnamoylphenylhydroxylaminates of copper, cadmium, indium, gallium and iron were determined by the method of measuring the solubility of precipitates in acid. The solubility of N-cinnamoylphenylhydroxalaminates of cadmium, indium, iron, titanium, zirconium, hafnium, niobium, tantalum, vanadium, molybdenum and tungsten in organic solvents was studied. Two-phase constants for the stability of the complexes were calculated. (author)

Experimental Observations of Nuclear Activity in Deuterated Materials Subjected to a Low-Energy Photon Beam

Science.gov (United States)

Steinetz, Bruce M.; Benyo, Theresa L.; Pines, Vladimir; Pines, Marianna; Forsley, Lawrence P.; Westmeyer, Paul A.; Chait, Arnon; Becks, Michael D.; Martin, Richard E.; Hendricks, Robert C.;

Aperture-time of oxygen-precursor for minimum silicon incorporation into the interface-layer in atomic layer deposition-grown HfO{sub 2}/Si nanofilms

Energy Technology Data Exchange (ETDEWEB)

Mani-Gonzalez, Pierre Giovanni [CINVESTAV-Unidad Querétaro, Querétaro 76230, Querétaro, Mexico and Departamento de Física y Matemáticas, Instituto de Ingeniería y Tecnología, Universidad Autónoma de Ciudad Juárez, Ave. Del Charro 450, Cd. Juárez C.P. 32310, Chihuahua (Mexico); Vazquez-Lepe, Milton Oswaldo [CINVESTAV-Unidad Querétaro, Querétaro 76230, Querétaro, Mexico and Departamento de Ingeniería de Proyectos, Universidad de Guadalajara, Guadalajara 45100, Jalisco (Mexico); Herrera-Gomez, Alberto, E-mail: aherrera@qro.cinvestav.mx [CINVESTAV-Unidad Querétaro, Querétaro 76230, Querétaro (Mexico)

2015-01-15

Hafnium oxide nanofilms were grown with atomic layer deposition on H-terminated Si (001) wafers employing tetrakis dimethyl amino hafnium (TDMA-Hf) and water as precursors. While the number of cycles (30) and the aperture-time for TDMA-Hf (0.08 s) were kept constant, the aperture-time (τ{sub H{sub 2O}}) for the oxidant-agent (H{sub 2}O) was varied from 0 to 0.10 s. The structure of the films was characterized with robust analysis employing angle-resolved x-ray photoelectron spectroscopy. In addition to a ∼1 nm hafnium oxide layer, a hafnium silicate interface layer, also ∼1 nm thick, is formed for τ{sub H{sub 2O}} > 0. The incorporation degree of silicon into the interface layer (i.e., the value of 1 − x in Hf{sub x}Si{sub 1−x}O{sub y}) shows a minimum of 0.32 for τ{sub H{sub 2O}} = 0.04 s. By employing the simultaneous method during peak-fitting analysis, it was possible to clearly resolve the contribution from the silicate and from oxide to the O 1s spectra, allowing for the assessment of the oxygen composition of each layer as a function of oxidant aperture time. The uncertainties of the peak areas and on the thickness and composition of the layers were calculated employing a rigorous approach.

Preparation of refractory cermet structures for lithium compatibility testing

Science.gov (United States)

Heestand, R. L.; Jones, R. A.; Wright, T. R.; Kizer, D. E.

1973-01-01

High-purity nitride and carbide cermets were synthesized for compatability testing in liquid lithium. A process was developed for the preparation of high-purity hafnium nitride powder, which was subsequently blended with tungsten powder or tantalum nitride and tungsten powders and fabricated into 3 in diameter billets by uniaxial hot pressing. Specimens were then cut from the billets for compatability testing. Similar processing techniques were applied to produce hafnium carbide and zirconium carbide cermets for use in the testing program. All billets produced were characterized with respect to chemistry, structure, density, and strength properties.

The vibrational spectra of some tetrachlorides in rare gas matrices with particular reference to the molecular shapes of ThCl4 and UCl4

International Nuclear Information System (INIS)

Arthers, S.A.; Beattie, I.R.

1984-01-01

Infrared spectra of tin, lead, hafnium, thorium, and uranium tetrachlorides isolated in inert gas matrices are reported. The results obtained for the tin, lead, and hafnium compounds follow the expected isotope patterns for a tetrahedral molecule except for the observation of additional weak features to high frequency of the all- 35 Cl isotopomers. By contrast for thorium tetrachloride the observed spectrum is not characteristic of a Tsub(d) molecule but can be fitted to a species with Csub(2v) symmetry. Similar results (although less detailed) were obtained for uranium tetrachloride. (author)

Metal oxide targets produced by the polymer-assisted deposition method

Energy Technology Data Exchange (ETDEWEB)

Garcia, Mitch A., E-mail: mitch@berkeley.ed [Department of Chemistry, Room 446 Latimer Hall, University of California Berkeley, Berkeley, CA 94720-1460 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Ali, Mazhar N.; Chang, Noel N.; Parsons-Moss, T. [Department of Chemistry, Room 446 Latimer Hall, University of California Berkeley, Berkeley, CA 94720-1460 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Ashby, Paul D. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Gates, Jacklyn M. [Department of Chemistry, Room 446 Latimer Hall, University of California Berkeley, Berkeley, CA 94720-1460 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Stavsetra, Liv [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Gregorich, Kenneth E.; Nitsche, Heino [Department of Chemistry, Room 446 Latimer Hall, University of California Berkeley, Berkeley, CA 94720-1460 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

2010-02-11

The polymer-assisted deposition (PAD) method was used to create crack-free homogenous metal oxide films for use as targets in nuclear science applications. Metal oxide films of europium, thulium, and hafnium were prepared as models for actinide oxides. Films produced by a single application of PAD were homogenous and uniform and ranged in thickness from 30 to 320 nm. Reapplication of the PAD method (six times) with a 10% by weight hafnium(IV) solution resulted in an equally homogeneous and uniform film with a total thickness of 600 nm.

Metal oxide targets produced by the polymer-assisted deposition method

International Nuclear Information System (INIS)

Garcia, Mitch A.; Ali, Mazhar N.; Chang, Noel N.; Parsons-Moss, T.; Ashby, Paul D.; Gates, Jacklyn M.; Stavsetra, Liv; Gregorich, Kenneth E.; Nitsche, Heino

2010-01-01

The polymer-assisted deposition (PAD) method was used to create crack-free homogenous metal oxide films for use as targets in nuclear science applications. Metal oxide films of europium, thulium, and hafnium were prepared as models for actinide oxides. Films produced by a single application of PAD were homogenous and uniform and ranged in thickness from 30 to 320 nm. Reapplication of the PAD method (six times) with a 10% by weight hafnium(IV) solution resulted in an equally homogeneous and uniform film with a total thickness of 600 nm.

High-resolution metallic magnetic calorimeters for {beta}-spectroscopy on {sup 187}rhenium and position resolved X-ray spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Porst, Jan-Patrick

2011-02-01

This thesis describes the development of metallic magnetic calorimeters (MMCs) for high resolution spectroscopy. MMCs are energy dispersive particle detectors based on the calorimetric principle which are typically operated at temperatures below 100 mK. The detectors make use of a paramagnetic temperature sensor to transform the temperature rise upon the absorption of a particle in the detector into a measurable magnetic flux change in a dc-SQUID. The application of MMCs for neutrino mass measurements and their advantages with respect to other approaches are discussed. In view of this application the development of an MMC optimized for {beta}-endpoint spectroscopy on {sup 187}rhenium is presented. A fully micro-fabricated X-ray detector is characterized and performs close to design values. Furthermore, a new technique to more efficiently couple rhenium absorbers mechanically and thermally to the sensor was developed and successfully tested. By employing a metallic contact, signal rise times faster than 5 {mu}s could be observed with superconducting rhenium absorbers. In addition to the single pixel detectors, an alternative approach of reading out multiple pixels was developed in this work, too. Here, the individual absorbers have a different thermal coupling to only one temperature sensor resulting in a distribution of different pulse shapes. Straightforward position discrimination by means of rise time analysis is demonstrated for a four pixel MMC and a thermal model of the detector is provided. Unprecedented so far, an energy resolution of less than {delta}E{sub FWHM}<5 eV for 5.9 keV X-rays was achieved across all absorbers. (orig.)

Evaluation of T-111 forced-convection loop tested with lithium at 13700C

International Nuclear Information System (INIS)

DeVan, J.H.; Long, E.L. Jr.

1975-04-01

A T-111 alloy (Ta--8 percent W--2 percent Hf) forced-convection loop containing molten lithium was operated 3000 h at a maximum temperature of 1370 0 C. Flow velocities up to 6.3 m/s were used. The results obtained in this forced-convection loop are very similar to those observed in lower velocity thermal-convection loops of T-111 containing lithium. Weight changes were determined at 93 positions around the loop. The maximum dissolution rate occurred at the maximum wall temperature of the loop and was less than 1.3 μ m/year. Mass transfer of hafnium, nitrogen, and, to a lesser extent, carbon occurred from the hotter to cooler regions. Exposed surfaces in the highest temperature region were found to be depleted in hafnium to a depth of 60 μ m with no detectable change in tungsten content. There was some loss in room-temperature tensile strength for specimens exposed to lithium at 1370 0 C, attributable to depletion of hafnium and nitrogen and to attendant grain growth. (U.S.)

Pacific 187Os/188Os isotope chemistry and U-Pb geochronology: Synchroneity of global Os isotope change across OAE 2

Science.gov (United States)

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

2015-10-01

Studies of OAE 2 sections beyond the Atlantic Ocean, Western Interior Seaway (WIS) and European pelagic shelf are limited. Here, we present initial osmium isotope stratigraphy (187Os/188Os-Osi) from two proto-Pacific sites that span the Cenomanian-Turonian boundary interval (CTBI): the Yezo Group (YG) section, Hokkaido, Japan, and the Great Valley Sequence (GVS), California, USA; to evaluate the 187Os/188Os seawater chemistry of the proto-Pacific. Additionally we combine new 206Pb/238U zircon CA-ID-TIMS geochronology from five volcanic tuff horizons of the Yezo Group section to test and facilitate inter-basinal integration with the WIS using radio-isotopically constrained age-depth models for both sections, and quantitatively constrain the absolute timing and duration of events across the CTBI. The YG shows an almost identical Osi profile to that of the WIS, and very similar to that of other sites of the proto-Atlantic and European pelagic oceans (Turgeon and Creaser, 2008; Du Vivier et al., 2014). The characteristics of the Osi profile are radiogenic and heterogeneous (∼0.55-0.85) prior to the OAE 2, and synchronous with the inferred OAE 2 onset the Osi abruptly become unradiogenic and remain relatively homogeneous (∼0.20-0.30) before showing a gradual return to more radiogenic Osi (∼ 0.70) throughout the middle to late OAE 2. A206Pb/238U zircon age of an interbedded tuff (HK017) in the adjacent horizon to the first unradiogenic Osi value constrains the age of the Osi inflection at 94.44 ± 0.14 Ma. This age, including uncertainty, agrees with the interpolated age of the same point in the Osi profile (94.28 ± 0.25 Ma) in the only other dated OAE 2 section, the WIS; indicating a coeval shift in seawater chemistry associated with volcanism at the OAE 2 onset at the levels of temporal resolution (ca. 0.1 Myr). Further, prior to the onset of OAE 2 an enhanced radiogenic inflection in the Osi profile of the YG is correlative, within uncertainty, with a similar

Dynamic Nuclear Polarization enhanced NMR at 187 GHz/284 MHz using an Extended Interaction Klystron amplifier.

Science.gov (United States)

Kemp, Thomas F; Dannatt, Hugh R W; Barrow, Nathan S; Watts, Anthony; Brown, Steven P; Newton, Mark E; Dupree, Ray

2016-04-01

A Dynamic Nuclear Polarisation (DNP) enhanced solid-state Magic Angle Spinning (MAS) NMR spectrometer which uses a 187 GHz (corresponding to (1)H NMR frequency of 284 MHz) Extended Interaction Klystron (EIK) amplifier as the microwave source is briefly described. Its performance is demonstrated for a biomolecule (bacteriorhodopsin), a pharmaceutical, and surface functionalised silica. The EIK is very compact and easily incorporated into an existing spectrometer. The bandwidth of the amplifier is sufficient that it obviates the need for a sweepable magnetic field, once set, for all commonly used radicals. The variable power (CW or pulsed) output from the EIK is transmitted to the DNP-NMR probe using a quasi-optic system with a high power isolator and a corrugated waveguide which feeds the microwaves into the DNP-NMR probe. Curved mirrors inside the probe project the microwaves down the axis of the MAS rotor, giving a very efficient system such that maximum DNP enhancement is achieved with less than 3 W output from the microwave source. The DNP-NMR probe operates with a sample temperature down to 90K whilst spinning at 8 kHz. Significant enhancements, in excess of 100 for bacteriorhodopsin in purple membrane (bR in PM), are shown along with spectra which are enhanced by ≈25 with respect to room temperature, for both the pharmaceutical furosemide and surface functionalised silica. These enhancements allow hitherto prohibitively time consuming experiments to be undertaken. The power at which the DNP enhancement in bR in PM saturates does not change significantly between 90K and 170 K even though the enhancement drops by a factor of ≈11. As the DNP build up time decreases by a factor 3 over this temperature range, the reduction in T1n is presumably a significant contribution to the drop in enhancement. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Precise determination of the spin-transfer coefficient K sub N sub sub N sub ' for n-vector p elastic scattering at 187 MeV

CERN Document Server

Wissink, S W; Franklin, W A; Jacobs, W W; Peterson, T; Rinckel, T; Sowinski, J; Stephenson, E J; Wolanski, M; Yang, H

2000-01-01

We have measured the normal-component spin-transfer observable K sub N sub sub N sub ' for n-vector p elastic scattering to a precision of approx +-0.014 at 12 angles in the far-backward region (110 deg. <= theta sub c sub m <= 170 deg. ) at a neutron bombarding energy of 187 MeV. This kinematic regime is of particular interest in that the scattering is mediated predominantly through exchange of a single charged pion, and hence is expected to depend sensitively on the strength of the pi sup+-N N coupling constant g sup 2 sub c , a quantity whose precise value remains highly controversial. The measurements described here were carried out at the upgraded Polarized Neutron Facility at IUCF. Details of our experimental apparatus, and the analysis procedures we employed, will be discussed, paying particular attention to potential sources of systematic error and their effect on the data. Our primary result is that preliminary values for K sub N sub sub N sub ' appear to agree most closely with the predictions...

Separation of zirconium and hafnium; Separation du zirconium et de l'hafnium

Energy Technology Data Exchange (ETDEWEB)

Saint-James, D [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1959-07-01

This account is more chemical than metallurgical in character. The reason for this is that so-called 'nuclear metal' must fulfil standards of purity which only chemical processes can attain. This paper must therefore be considered as a preliminary study, from which the metallurgists can form an idea of the treatments leading to the production of the metal. (author) [French] Cet expose a un caractere chimique plutot que metallurgique. La raison en est que le metal dit 'nucleaire' a des exigences de purete que seuls des processus chimiques peuvent satisfaire. Il faut donc considerer cet expose comme un preliminaire, permettant de donner une idee aux metallurgistes des traitements qui aboutissent a l'elaboration du metal. (auteur)

Point defect engineering strategies to retard phosphorous diffusion in germanium

KAUST Repository

Tahini, H. A.; Chroneos, Alexander I.; Grimes, Robin W.; Schwingenschlö gl, Udo; Bracht, Hartmut A.

2013-01-01

The diffusion of phosphorous in germanium is very fast, requiring point defect engineering strategies to retard it in support of technological application. Density functional theory corroborated with hybrid density functional calculations are used to investigate the influence of the isovalent codopants tin and hafnium in the migration of phosphorous via the vacancy-mediated diffusion process. The migration energy barriers for phosphorous are increased significantly in the presence of oversized isovalent codopants. Therefore, it is proposed that tin and in particular hafnium codoping are efficient point defect engineering strategies to retard phosphorous migration. © the Owner Societies 2013.

PRODUCTION OF HAFNIUM METAL

Science.gov (United States)

Elger, G.W.; Boubel, R.W.

1963-01-01

This patent deals with a process of producing pure Hf metal from oxygen- contaminated gaseous Hf chloride. The oxygen compounds in the chioride gas are halogenated by contacting the gas at elevated temperature with Cl/sub 2/ in the presence of C. The Hf chloride, still in gaseous form, is contacted with molten Mg whereby Hf metal is formed and condensed on the Mg. (AEC)

MIVOC method at the mVINIS ion source

Directory of Open Access Journals (Sweden)

Jovović Jovica

2007-01-01

Full Text Available Based on the metal-ions-from-volatile-compounds (MIVOC method with the mVINIS ion source, we have produced multiply charged ion beams from solid substances. Highly in tense, stable multiply charged ion beams of several solid substances with high melting points were extracted by using this method. The spectrum of multiply charged ion beams obtained from the element hafnium is presented here. For the first time ever, hafnium ion beam spectra were recorded at an electron cyclotron resonance ion source. Multiply charged ion beams from solid substances were used to irradiate the polymer, fullerene and glassy carbon samples at the channel for the modification of materials.

Thickness independent reduced forming voltage in oxygen engineered HfO{sub 2} based resistive switching memories

Energy Technology Data Exchange (ETDEWEB)

Sharath, S. U., E-mail: sharath@oxide.tu-darmstadt.de; Kurian, J.; Komissinskiy, P.; Hildebrandt, E.; Alff, L. [Institute of Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany); Bertaud, T.; Walczyk, C.; Calka, P. [IHP, Im Technologiepark 25, 15236 Frankfurt Oder (Germany); Schroeder, T. [IHP, Im Technologiepark 25, 15236 Frankfurt Oder (Germany); Brandenburgische Technische Universität, Konrad-Zuse-Strasse 1, 03046 Cottbus (Germany)

2014-08-18

The conducting filament forming voltage of stoichiometric hafnium oxide based resistive switching layers increases linearly with layer thickness. Using strongly reduced oxygen deficient hafnium oxide thin films grown on polycrystalline TiN/Si(001) substrates, the thickness dependence of the forming voltage is strongly suppressed. Instead, an almost constant forming voltage of about 3 V is observed up to 200 nm layer thickness. This effect suggests that filament formation and switching occurs for all samples in an oxidized HfO{sub 2} surface layer of a few nanometer thickness while the highly oxygen deficient thin film itself merely serves as a oxygen vacancy reservoir.

Characterization of electron beam deposited thin films of HfO2 and binary thin films of (HfO2:SiO2) by XRD and EXAFS measurements

International Nuclear Information System (INIS)

Das, N.C.; Sahoo, N.K.; Bhattacharyya, D.; Thakur, S.; Kamble, N.M.; Nanda, D.; Hazra, S.; Bal, J.K.; Lee, J.F.; Tai, Y.L.; Hsieh, C.A.

2009-10-01

In this report, we have discussed the microstructure and the local structure of composite thin films having varying hafnia and silica compositions and prepared by reactive electron beam evaporation. XRD and EXAFS studies have confirmed that the pure hafnium oxide thin film has crystalline microstructure whereas the films with finite hafnia and silica composition are amorphous. The result of EXAFS analysis has shown that the bond lengths as well as coordination numbers around hafnium atom change with the variation of hafnia and silica compositions in the thin film. Finally, change of bond lengths has been correlated with change of refractive index and band gap of the composite thin films. (author)

Radiation protection 1/87

International Nuclear Information System (INIS)

Holeczke, F.; Kaercher, K.H.; Kainberger, F.; Mader, H.; Seyss, R.

1987-01-01

There is a paper on medical first aid after radiation accidents and another on positive effects of low-dose irradiation which are treated separately. In addition there are four contributions on question of conventional X-ray diagnosis. (G.Q.)

187 Résumé

African Journals Online (AJOL)

ANIS

Structure physicochimique et phytoplanctonique du lac dayet aoua (moyen atlas - Maroc). Anissi FAZUL1, Saâd ... Le Maroc de par sa position géographique dispose d'une grande diversité de milieux aquatiques marins et continentaux. Ainsi, il est .... transparentes ne présente aucun signe d'eutrophisation. Des résultats ...

Effect of zirconium purity on the glass-forming-ability and notch toughness of Cu{sub 43}Zr{sub 43}Al{sub 7}Be{sub 7}

Energy Technology Data Exchange (ETDEWEB)

Andersen, Laura M. [Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA (United States); Hofmann, Douglas C. [Materials Development and Manufacturing Technology Group, NASA Jet Propulsion Laboratory/California Institute of Technology, MS 18-105, 4800 Oak Grove Dr. Pasadena, CA 91109 (United States); Vecchio, Kenneth S., E-mail: kvecchio@ucsd.edu [Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA (United States)

2016-09-30

The effect of substituting standard grade zirconium lump (99.8% excluding up to 4% hafnium) for high purity zirconium crystal bar (99.5%) in a Cu{sub 43}Zr{sub 43}Al{sub 7}Be{sub 7} bulk metallic glass (BMG) is examined. The final hafnium content in the BMG specimens was found to range from 0 to 0.44 at%. Introducing low purity zirconium significantly decreased the glass-forming-ability and reduced the notch toughness of the BMG. In contrast, when adding high purity hafnium to Cu{sub 43}Zr{sub 43}Al{sub 7}Be{sub 7} made with high purity zirconium, no significant change in the glass-forming-ability or toughness was observed. This suggests that the introduction of low purity zirconium in BMGs creates a more complex response than a simple addition of hafnium. It is likely that other impurities in the material, such as oxygen, play a role in the complex crystallization kinetics and change in mechanical properties. The notch toughness was measured through four-point-bend tests, which showed a decrease in notch toughness from an average of ~53 MPa m{sup 1/2} for the high purity samples to an average of ~29 MPa m{sup 1/2} with full substitution of low purity zirconium. A similar decrease in glass-forming-ability and toughness is observed in commercially synthesized high purity Cu{sub 43}Zr{sub 43}Al{sub 7}Be{sub 7}. The large scale commercial process is expected to introduced some unintentional impurities, which decrease the properties of the BMG in the same way as the lower purity elements. Lastly, Weibull statistics are used to provide an analysis of variability in toughness for both ingots synthesized in a small laboratory arc-melter and those synthesized commercially.

Development of new extraction agents for separation of rare radioactive elements

International Nuclear Information System (INIS)

Hala, J.; Navratil, O.; Prihoda, J.; Smola, J.

1977-01-01

Certain transition elements, such as rhodium and palladium may be recovered from waste solutions produced in spent fuel reprocessing. The extraction of palladium was studied using sulfur compounds of the sulfide and sulfoxide types and the effects were investigated of the individual factors on palladium distribution between the aqueous and the organic phases. The possibility of separating hafnium in the form of extractable complexes was tested on several systems. Studied in more detail were mainly the complexes of hafnium with pyrocatechol violet, xylenol orange, and tributyl phosphate. The extraction of other metals, mainly of scandium, europium and indium was investigated in detail in the system acid aqueous phase - organophosphinic acids solution in benzene. (L.K.)

Novel Manufacturing Process for Unique Mixed Carbide Refractory Composites, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — This STTR Phase I project will establish the feasibility of an innovative manufacturing process to fabricate a range of unique hafnium/silicon based carbide...

Cobalt catalysts, and use thereof for the conversion of methanol and for fischer-tropsch synthesis, to produce hydrocarbons

International Nuclear Information System (INIS)

Mauldin, C.H.; Davis, S.M.; Arcuri, K.B.

1988-01-01

This patent describes a process useful for the conversion of methanol to hydrocarbons which comprises contacting the methanol at reaction conditions with a catalyst which comprises from about 2 percent to about 25 percent cobalt, based on the weight of the catalyst composition, composited with titania, or a titania-containing support, to which is added a zirconium, hafnium, cerium, or uranium promoter, the weight ratio of the zirconium, hafnium, cerium, or uranium metal:cobalt being greater than about 0.010:1; the reaction conditions being defined within ranges as follows: Methanol:H/sub 2/ ratio: greater than about 4:1, Space Velocities, Hr/sup -1/:about 0.1 to 10, Temperatures, 0 C.:about 150 to 350, Methanol Partial Pressure, psia: about 100 to 1000

Ceramic component for M.H.D electrode

International Nuclear Information System (INIS)

Marchant, D.D.; Bates, J.L.

1980-01-01

A ceramic component which exhibits electrical conductivity down to near room temperatures has the formula: Hfsub(x)Insub(y)Asub(z)O 2 where x = 0.1 to 0.4, y = 0.3 to 0.6, z = 0.1 to 0.4 and A is a rare earth or yttrium. The rare earth may be Yb, Tb, Pr or Ce. The component is suitable for use in the fabrication of MHD electrodes or as the current lead-out portion of a composite electrode with other ceramic components. An MHD electrode comprises a cap of a known ceramic, e.g. stabilised zirconium or hafnium oxide or terbium stabilised hafnium, a current lead-out ceramic according to the invention, and a copper frame. (author)

40 CFR 302.6 - Notification requirements.

Science.gov (United States)

2010-07-01

..., phosphate, tin, zircon, hafnium, vanadium, monazite, and rare earth mines. Land disturbance incidental to..., chromium, copper, lead, nickel, selenium, silver, thallium, or zinc is not required if the mean diameter of...

Electrochemical investigations of ion-implanted oxide films

International Nuclear Information System (INIS)

Schultze, J.W.; Danzfuss, B.; Meyer, O.; Stimming, U.

1985-01-01

Oxide films (passive films) of 40-50 nm thickness were prepared by anodic polarization of hafnium and titanium electrodes up to 20 V. Multiple-energy ion implantation of palladium, iron and xenon was used in order to obtain modified films with constant concentration profiles of the implanted ions. Rutherford backscattering, X-ray photoelectron spectroscopy measurements and electrochemical charging curves prove the presence of implanted ions, but electrochemical and photoelectrochemical measurements indicate that the dominating effect of ion implantation is the disordering of the oxide film. The capacity of hafnium electrodes increases as a result of an increase in the dielectric constant D. For titanium the Schottky-Mott analysis shows that ion implantation causes an increase in D and the donor concentration N. Additional electronic states in the band gap which are created by the implantation improve the conductivity of the semiconducting or insulating films. This is seen in the enhancement of electron transfer reactions and its disappearance during repassivation and annealing. Energy changes in the band gap are derived from photoelectrochemical measurements; the absorption edge of hafnium oxide films decreases by approximately 2 eV because of ion implantation, but it stays almost constant for titanium oxide films. All changes in electrochemical behavior caused by ion implantation show little variation with the nature of the implanted ion. Hence the dominating effect seems to be a disordering of the oxide. (Auth.)

Microstructural characterization of as-cast hf-b alloys

Directory of Open Access Journals (Sweden)

João Carlos Jânio Gigolotti

2012-04-01

Full Text Available An accurate knowledge of several metal-boron phase diagrams is important to evaluation of higher order systems such as metal-silicon-boron ternaries. The refinement and reassessment of phase diagram data is a continuous work, thus the reevaluation of metal-boron systems provides the possibility to confirm previous data from an investigation using higher purity materials and better analytical techniques. This work presents results of rigorous microstructural characterization of as-cast hafnium-boron alloys which are significant to assess the liquid composition associated to most of the invariant reactions of this system. Alloys were prepared by arc melting high purity hafnium (minimum 99.8% and boron (minimum 99.5% slices under argon atmosphere in water-cooled copper crucible with non consumable tungsten electrode and titanium getter. The phases were identified by scanning electron microscopy, using back-scattered electron image mode and X-ray diffraction. In general, a good agreement was found between our data and those from the currently accepted Hafnium-Boron phase diagram. The phases identified are αHfSS and B-RhomSS, the intermediate compounds HfB and HfB2 and the liquide L. The reactions are the eutectic L ⇔ αHfSS + HfB and L ⇔ HfB2 + B-Rhom, the peritectic L + HfB2 ⇔ HfB and the congruent formation of HfB2.

WWER-440 local power peaking experiment with/without Hf inserts in the LR-0 reactor

International Nuclear Information System (INIS)

Josek, R.; Hudec, F.; Rypar, V.

2006-01-01

One of the known issues of the WWER-440 reactors is the control rod coupler induced power peaking in the neighbouring fuel assemblies. The effect has been discovered some years ago and is believed to be the cause of several fuel failures during operation in WWER-440 reactors. The effect itself is due to over-moderation and small absorption in the region of control rod coupler, leading to increase in thermal neutron flux and hence to power flare-up in the neighbouring fuel pins. The fuel vendor tackled the problem by attaching hafnium inserts on the inside of the control assembly box. The experiment performed in the LR-0 reactor was focused on the axial and radial power profiles in the vicinity of the control assembly with and without the hafnium inserts. The results of measurements with zero boron concentration are presented. The hafnium insert causes a decrease in peaking factor of about 30% in selected pins close to the control assembly. The measurements are compared with calculations performed with the MCNP-4C code. The compared variables are: the axial fission density distributions; peking factors and peaking factor decrease due to Hf insert. The MCNP results are accurate with respect to the experimental results. A series of benchmarks is being prepared on the basis of these measurements

Design of thermoelectrically highly efficient Heusler compounds using phase separations and nano-composites under an economic point of view

Science.gov (United States)

Balke, Benjamin

Half-Heusler (HH) compounds are one of the most promising candidates for thermoelectric materials for automotive and industrial waste heat recovery applications. In this talk, I will give an overview about our recent investigations of phase separations in HH thermoelectrics, focusing on the ternary system TiNiSn-ZrNiSn-HfNiSn. I will show how we adapted this knowledge to design a p-type HH compound which exhibits a ZT that is increased by 130% compared to the best published bulk p-type Heusler. I will also present how we used the phase separation to design thermoelectric highly efficient nano-composites of different single-phase materials. Since the price for Hafnium doubled within the last year, our research focused on the design of HH compounds without Hafnium. I will present a very recent calculation on ZT per Euro and efficiency per Euro for various materials followed by our latest very promising results for n-type Heusler compunds without Hafnium resulting in 20 times higher ZT/Euro values. These results strongly underline the importance of phase separations as a powerful tool for designing highly efficient materials for thermoelectric applications that fulfill the industrial demands for a thermoelectric converter. The author gratefully acknowledges financial support by the thermoHEUSLER2 Project (Project No. 19U15006F) of the German Federal Ministry of Economics and Technology (BMWi).

Mesoporous TiO2 powders as host matrices for iron nanoparticles. Effect of the preparation procedure and doping with Hf

Czech Academy of Sciences Publication Activity Database

Dimitrov, M.; Ivanova, R.; Velinov, N.; Henych, Jiří; Slušná, Michaela; Štengl, Václav; Tolasz, Jakub; Mitov, I.; Tsoncheva, T.

2016-01-01

Roč. 7, JUL (2016), s. 56-63 ISSN 2352-507X Institutional support: RVO:61388980 Keywords : Mesoporous titania * Hafnium doping * Iron modification * Ethyl acetate oxidation * Methanol decomposition Subject RIV: CA - Inorganic Chemistry

Cathodoluminescence of Irradiated Hafnium Dioxide

Science.gov (United States)

2011-03-01

Martin and Michael Rhoby for their hard work in fixing assorted problems that cropped up during the course of my thesis work. Emily A. Purcell...Cathodoluminescence Microscopy of Inorganic Solids. New York: Plenum Press, 1990. [13] D. Drouin, A. R. Couture, D. Joly , X. Tastet, V. Aimez and R. Gauvin

Zirconium Zr and hafnium Hf

International Nuclear Information System (INIS)

Busev, A.I.; Tiptsova, V.G.; Ivanov, V.M.

1978-01-01

The basic methods for extracting and determining Zr(4) and Hf(4) are described. Diantipyrinemethane and its alkyl homologs selectively extract Zr and Hf from HNO 3 solutions in the presence of nitrates. Zr is selectively extracted with tetraethyldiamide of heptyl phosphoric acid (in benzene) as well as with 2-thenoyltrifluoroacetone (in an acid). The latter reagents is suitable for rapid determination of 95 Zr in a mixture with 95 Nb and other fragments. The complexometric determination of Zr is based on formation of a stable complex of Zr with EDTA. The titration is carried out in the presence of n-sulfobenzene-azo-pyrocatechol, eriochrome black T. The determination is hindered by Hf, fluoride-, phosphate-, oxalate- and tartrate-ions. The method is used for determining Zr in zircon and eudialyte ore. Zr is determined photometrically with the aid of xylenol orange, arsenazo 3 and pyrocatechol violet (in phosphorites). Hf is determined in the presence of Zr photometrically with the aid of xylenol orange or methyl-thymol blue. The method is based on Zr being masked with hydrogen peroxide in the presence of sulfate-ions

Alkali metal hafnium oxide scintillators

Science.gov (United States)

Bourret-Courchesne, Edith; Derenzo, Stephen E.; Taylor, Scott Edward

2018-05-08

The present invention provides for a composition comprising an inorganic scintillator comprising an alkali metal hafnate, optionally cerium-doped, having the formula A2HfO3:Ce; wherein A is an alkali metal having a valence of 1, such as Li or Na; and the molar percent of cerium is 0% to 100%. The alkali metal hafnate are scintillators and produce a bright luminescence upon irradiation by a suitable radiation.

High-pressure torsion of hafnium

International Nuclear Information System (INIS)

Edalati, Kaveh; Horita, Zenji; Mine, Yoji

2010-01-01

Pure Hf (99.99%) is processed by high-pressure torsion (HPT) under pressures of 4 and 30 GPa to form an ultrafine-grained structure with a gain size of ∼180 nm. X-ray diffraction analysis shows that, unlike Ti and Zr, no ω phase formation is detected after HPT processing even under a pressure of 30 GPa. A hydride formation is detected after straining at the pressure of 4 GPa. The hydride phase decomposes either by application of a higher pressure as 30 GPa or by unloading for prolong time after HPT processing. Microhardness, tensile and bending tests show that a high hardness (360 Hv) and an appreciable ductility (8%) as well as high tensile and bending strength (1.15 and 2.75 GPa, respectively) are achieved following the high-pressure torsion.

X-ray target with substrate of molybdenum alloy

International Nuclear Information System (INIS)

Hirsch, H.H.

1980-01-01

Rotary targets for x-ray tubes are provided comprising a molybdenum base body alloyed with a stabilizing proportion of iron, silicon, cobalt, tantalum, niobium, hafnium, stable metal oxide, or a mixture of the preceding

Control rod

International Nuclear Information System (INIS)

Igarashi, Takao; Sugawara, Satoshi; Yoshimoto, Yuichiro; Saito, Shozo; Fukumoto, Takashi.

1987-01-01

Purpose: To reduce the weight and thereby obtain satisfactory operationability of control rods by combining absorbing nuclear chain type neutron absorbers and conventional type neutron absorbers in the axial direction of blades. Constitution: Neutron absorber rods and long life type neutron absorber rods are disposed in a tie rod and a sheath. The neutron absorber rod comprises a poison tube made of stainless steels and packed with B 4 C powder. The long life type neutron absorber rod is prepared by packing B-10 enriched boron carbide powder into a hafnium metal rod, hafnium pipe, europium and stainless made poison tube. Since the long life type absorber rod uses HF as the absorbing nuclear chain type neutron absorber, it absorbs neutrons to form new neutron absorbers to increase the nuclear life. (Yoshino, Y.)

Thermodynamic study of the MWG system/components and measurement of the oxygen partial pressure in the heat source capsule

International Nuclear Information System (INIS)

David, D.J.

1980-01-01

A thermodynamic study of the Milliwatt Generator heat source capsule was performed to determine the effects of the oxide fuel on container materials at elevated temperatures in order to evaluate the factors affecting embrittlement of T-111 alloy. The study indicates that relatively slow oxidation of the T-111 of the capsule occurs during pretreatment. Yttrium added to the 238 PuO 2 fuel charge is functioning in its designed role as an oxygen getter and is stabilizing at an O/Pu ratio of 1.75. The free energy of formation of hafnium oxide has been measured and found to be -70632 cal/mole; this suggests that the ability of hafnium to strongly function as an oxygen getter may be largely determined by the kinetics, and the free energy may play a lesser role

Development of Advanced Environmental Barrier Coatings for SiC/SiC Ceramic Matrix Composites: Path Toward 2700 F Temperature Capability and Beyond

Science.gov (United States)

Zhu, Dongming; Harder, Bryan; Hurst, Janet B.; Good, Brian; Costa, Gustavo; Bhatt, Ramakrishna T.; Fox, Dennis S.

2017-01-01

Advanced environmental barrier coating systems for SiC-SiC Ceramic Matrix Composite (CMC) turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant coating development challenges is to achieve prime-reliant environmental barrier coating systems to meet the future 2700F EBC-CMC temperature stability and environmental durability requirements. This presentation will emphasize recent NASA environmental barrier coating system testing and down-selects, particularly the development path and properties towards 2700-3000F durability goals by using NASA hafnium-hafnia-rare earth-silicon-silicate composition EBC systems for the SiC-SiC CMC turbine component applications. Advanced hafnium-based compositions for enabling next generation EBC and CMCs capabilities towards ultra-high temperature ceramic coating systems will also be briefly mentioned.

Neutron cross section measurements using the ORELA: 40Ar(n,x), 40Ca(n,x), 22Ne(n,γ) 187Os(n,n'), 186187Os(n,nn'γ), the stable tellurium isotopes (n,γ) and 205Tl(n,nγ). Progress report, September 1, 1981-August 31, 1982

International Nuclear Information System (INIS)

Winters, R.R.

1982-08-01

The research reported is in two major areas, nuclear physics and astrophysics. In nuclear, studies in the use of an optical model nuclear potential to describe the experimentally determined scattering matrix, and reduced neutron widths for s/sub 1/2/ resonances in 32 S. In astrophysics, total and capture cross sections for 186 Os, 187 Os, and 188 Os, 22 Ne(n,γ) resonances, and capture cross sections for 148 Sm, 149 Sm, and 150 Sm, were measured

10 CFR Appendix L to Part 110 - Illustrative List of Byproduct Materials Under NRC Export/Import Licensing Authority a

Science.gov (United States)

2010-01-01

... material produced, extracted, or converted for use for a commercial, medical, or research activity...) Gallium 72 (Ga 72) Germanium 68 (Ge 68) Germanium 71 (Ge 71) Gold 198 (Au 198) Gold 199 (Au 199) Hafnium...

Organizing Committee Advisory Committee 187

Indian Academy of Sciences (India)

Organizing Committee. V M Datar (Chairman). Bhabha Atomic Research Centre, Mumbai, India. D C Biswas (Convener). Bhabha Atomic Research Centre, Mumbai, India. K Mahata (Secretary). Bhabha Atomic Research Centre, Mumbai, India. Z Ahmed. Bhabha Atomic Research Centre, Mumbai, India. P V Bhagwat.

32 CFR 187.3 - Definitions.

Science.gov (United States)

2010-07-01

... Defense Department of Defense OFFICE OF THE SECRETARY OF DEFENSE ENVIRONMENT ENVIRONMENTAL EFFECTS ABROAD... physical environment, and it excludes social, economic, and other environments. Social and economic effects... or jointly with any other foreign government; and any area that is the responsibility of an...

187 DISPLACEMENT AND ENVIRONMENTAL PROTECTION

African Journals Online (AJOL)

Fr. Ikenga

The national and international communities are confronted with the monumental task of ... displacement and environmental protection present a vicious cycle which today has ... Thus, issues of environmental protection viz-a-viz investment and .... out the conditions for product or process standards, the use of best available ...

GPCR Interaction: 187 [GRIPDB[Archive

Lifescience Database Archive (English)

Full Text Available tivation are reduced by activation of CXCR4 in advance. In addition, calcium mobilization assays show these cross-desensitization...tion is not responsible for desensitization between these receptors. 18533278 Calcium mobilization assay NP_001008540.1 ...

Age-specific and sex-specific mortality in 187 countries, 1970-2010: a systematic analysis for the Global Burden of Disease Study 2010.

Science.gov (United States)

Wang, Haidong; Dwyer-Lindgren, Laura; Lofgren, Katherine T; Rajaratnam, Julie Knoll; Marcus, Jacob R; Levin-Rector, Alison; Levitz, Carly E; Lopez, Alan D; Murray, Christopher J L

2012-12-15

Estimation of the number and rate of deaths by age and sex is a key first stage for calculation of the burden of disease in order to constrain estimates of cause-specific mortality and to measure premature mortality in populations. We aimed to estimate life tables and annual numbers of deaths for 187 countries from 1970 to 2010. We estimated trends in under-5 mortality rate (children aged 0-4 years) and probability of adult death (15-59 years) for each country with all available data. Death registration data were available for more than 100 countries and we corrected for undercount with improved death distribution methods. We applied refined methods to survey data on sibling survival that correct for survivor, zero-sibling, and recall bias. We separately estimated mortality from natural disasters and wars. We generated final estimates of under-5 mortality and adult mortality from the data with Gaussian process regression. We used these results as input parameters in a relational model life table system. We developed a model to extrapolate mortality to 110 years of age. All death rates and numbers have been estimated with 95% uncertainty intervals (95% UIs). From 1970 to 2010, global male life expectancy at birth increased from 56·4 years (95% UI 55·5-57·2) to 67·5 years (66·9-68·1) and global female life expectancy at birth increased from 61·2 years (60·2-62·0) to 73·3 years (72·8-73·8). Life expectancy at birth rose by 3-4 years every decade from 1970, apart from during the 1990s (increase in male life expectancy of 1·4 years and in female life expectancy of 1·6 years). Substantial reductions in mortality occurred in eastern and southern sub-Saharan Africa since 2004, coinciding with increased coverage of antiretroviral therapy and preventive measures against malaria. Sex-specific changes in life expectancy from 1970 to 2010 ranged from gains of 23-29 years in the Maldives and Bhutan to declines of 1-7 years in Belarus, Lesotho, Ukraine, and Zimbabwe

Hafnium and neodymium isotopes and REY distribution in the truly dissolved, nanoparticulate/colloidal and suspended loads of rivers in the Amazon Basin, Brazil

Science.gov (United States)

Merschel, Gila; Bau, Michael; Schmidt, Katja; Münker, Carsten; Dantas, Elton L.

2017-09-01

Radiogenic isotopes in river sediments and river waters have been widely used in provenance studies, as these samples naturally integrate the geology/chemistry of the entire catchment. While the Hf and Nd isotope systems are coupled during igneous processes, they are decoupled during supergene processes at the Earth's surface, which is reflected by the isotope composition of riverine sediments. We present the first data for both Hf and Nd isotope compositions of the dissolved (0.2 μm-filtrates rich in nanoparticles and colloids, NPCs) and the truly dissolved (1 kDa-ultrafiltrates) load of rivers. Hafnium and Nd isotope compositions and concentrations of the Rare Earths and Yttrium (REY) and Hf were determined for suspended particles (>0.2 μm) as well as for the dissolved and the truly dissolved load of the Rio Solimões, the Amazon's largest tributary draining the Andes, and of the Rio Negro, an organic NPC- and particle-rich river draining the rainforest of northern Amazonia. We also analyzed the Nd isotope compositions of suspended sediments and 0.2 μm-filtered water samples from the Amazon River and its tributaries Rio Tapajos, Rio Xingu and Rio Jari. Our novel results clearly show that the decoupling of the Hf and Nd isotope systems is related to incongruent weathering processes on the continent, as this decoupling can already be observed in the different Hf and Nd pools, i.e. in the particulate, the NPC-dominated dissolved and the truly dissolved load of rivers. In the Rio Negro and Rio Solimões, a strong particle size-dependent difference in Hf isotope composition is observed. Values of εHf become more radiogenic as filter poresize decreases, which can be related to the density- and size-dependent distribution of Hf-rich minerals, e.g. zircons, and their absence from the truly dissolved pool. In contrast, the Nd isotope composition of Amazonian river waters reflects that of their catchment geology. Tributaries draining the Precambrian Brazilian and

Fabrication of cermet bearings for the control system of a high temperature lithium cooled nuclear reactor

Science.gov (United States)

Yacobucci, H. G.; Heestand, R. L.; Kizer, D. E.

1973-01-01

The techniques used to fabricate cermet bearings for the fueled control drums of a liquid metal cooled reference-design reactor concept are presented. The bearings were designed for operation in lithium for as long as 5 years at temperatures to 1205 C. Two sets of bearings were fabricated from a hafnium carbide - 8-wt. % molybdenum - 2-wt. % niobium carbide cermet, and two sets were fabricated from a hafnium nitride - 10-wt. % tungsten cermet. Procedures were developed for synthesizing the material in high purity inert-atmosphere glove boxes to minimize oxygen content in order to enhance corrosion resistance. Techniques were developed for pressing cylindrical billets to conserve materials and to reduce machining requirements. Finishing was accomplished by a combination of diamond grinding, electrodischarge machining, and diamond lapping. Samples were characterized in respect to composition, impurity level, lattice parameter, microstructure and density.

The determination of light elements in heavy matrix using proton induced X-ray emission

International Nuclear Information System (INIS)

Levenets, V.V.; Omel'nik, A.P.; Shchur, A.A.; Chernov, A.E.; Usikov, N.P.; Zats, A.V.

2007-01-01

In this report the possibility of determination of light impurities in heavy matrixes is studied using proton induced X-Ray emission. The wide-band X-ray emission filter made from pyrolytic graphite was used in spectrometric scheme of experiment. The results of studying of filter features in energy range of X-ray emission from 4 to 12 keV were presented. The possibilities were examined of application of pyrolytic graphite filter to modify the X-rays spectrum for determination of iron, using characteristic emission of K-series, and hafnium, using L-series, in substances on base of zirconium (glasses, alloys etc.). It was shown, that the using of similar filter allows to reach the significant improving of metrological characteristics of analysis of mentioned impurities: the limits of detection of iron and hafnium were lowered single-order of magnitude. (authors)

Chemical effects in x-ray emission spectra

International Nuclear Information System (INIS)

Fernandes, N.G.

1982-01-01

The chemical bond influence in X-ray emission spectra of hafnium, iodine, iron, sulphur, aluminium and magnesium is detected. The position of one X-ray emission line is determined by three methods: parabolic profile; Gaussian distribution and extra-heavy maximum. (author)

Highly stable thin film transistors using multilayer channel structure

KAUST Repository

Nayak, Pradipta K.; Wang, Zhenwei; Anjum, Dalaver H.; Hedhili, Mohamed N.; Alshareef, Husam N.

2015-01-01

We report highly stable gate-bias stress performance of thin film transistors (TFTs) using zinc oxide (ZnO)/hafnium oxide (HfO2) multilayer structure as the channel layer. Positive and negative gate-bias stress stability of the TFTs was measured

EXPERIMENTAL ANALYSIS OF THE HEALING PROCESS IN THE AREA OF TIBIAL BONE FRACTURE

Directory of Open Access Journals (Sweden)

I. F. Аkhtyamov

2016-01-01

Full Text Available Purpose. To quantify the density of the cortical bone of the tibia in the area of reparative regeneration and the state of the vascular bed (hemodynamics of the operated limb under intramedullary osteosynthesis using pins coated with titanium and hafnium nitrides. Materials and methods. In the experiment, changes in the bone density and the characteristics of the local blood supply were studied on 40 outbred rabbits which underwent intramedullary osteosynthesis by the use of pins with a nanocoating based on superhard compounds which consist of titanium and hafnium nitrides and pins without a coating. Using color Doppler mode helped to evaluate the condition of the vascular bed proximally to the fracture site. Results. It is noted that the use of pins with the described coating above did not violate the osteoregeneration staging. The density of the cortical bone in the test group exceeded that of the comparison group by an average of 30%. Bone remodeling processes in the test group completed at an earlier date, as determined by the higher rates of its density. In the study of the vascular bed of the operated limb, it was found that on the 10th day of the experiment, an increase in the maximal velocity of the blood flow was recorded (TAMAX. In animals of the test group this index approached preoperative values on the 30th day, while in animals of the comparison group this index approached the initial values only by the 60th day. Conclusion. The use of implants coated with titanium and hafnium nitrides which are characterized by high strength, thermal and chemical stability is accompanied by the formation of a cortical bone in the area of osteotomy with higher density characteristics. The changes which are typical of the vasodilatation in the area of injury in the early postoperative period can be regarded as a positive factor in the formation of primary bone union. In the group where implants coated with titanium and hafnium nitrides were used

Behavior of uranium and its surrogates in molten aluminosilicate glasses in contact with liquid metals

International Nuclear Information System (INIS)

Chevreux, Pierrick

2016-01-01

This study concerns an innovative process used for conditioning nuclear waste that contain metallic parts contaminated with actinides. High actinides concentrations are expected to be incorporated in the glass melt in contact with the molten metals. Among these metals, aluminum and/or stainless steel impose a strongly reducing environment to the glass melt involving redox reactions. These reactions modify actinides oxidation states and therefore change their solubilities in the glass and could also reduce them into the metallic form. In this work, we focus on the behavior of uranium and its surrogates, namely hafnium and neodymium, in aluminosilicate glasses from the Na 2 O-CaO-SiO 2 -Al 2 O 3 system melted in highly reducing conditions. The first step consists in comparing the hafnium and uranium solubilities in the glass as functions of redox conditions and glass composition. A methodology has been set up and a specific device has been used to control the oxygen fugacity and the alkali content of the glass. The results show that uranium is far less soluble in the glass than hafnium (Hf(IV)) in reducing conditions. The uranium solubility ranges from 4 to 7 wt% UO 2 for an oxygen fugacity below 10 -14 atm at 1250 C-1400 C. Uranium oxidation states have been investigated by X-ray absorption spectroscopy (XANES). It has been pointed out that U(IV) is the main form in the glass for such imposed oxygen fugacities. The second step of this work is to identify the glass-metal interaction mechanisms in order to determine the localization of uranium and its surrogates (Nd, Hf) in the glass-metal system. Mechanisms are mostly ruled by the presence of metallic aluminum and are similar for uranium, neodymium and hafnium. Glass-metal interaction kinetics demonstrate that uranium and its surrogates can temporarily be reduced into the metallic form for particular conditions. A re-oxidation occurs with time which is in good agreement with thermodynamics. Regarding uranium, the re

A Fully Transparent Resistive Memory for Harsh Environments

KAUST Repository

Yang, Po-Kang; Ho, Chih-Hsiang; Lien, Der-Hsien; Duran Retamal, Jose Ramon; Kang, Chen-Fang; Chen, Kuan-Ming; Huang, Teng-Han; Yu, Yueh-Chung; Wu, Chih-I; He, Jr-Hau

2015-01-01

A fully transparent resistive memory (TRRAM) based on Hafnium oxide (HfO2) with excellent transparency, resistive switching capability, and environmental stability is demonstrated. The retention time measured at 85 °C is over 3 × 104 sec

Mafic-silicic magma interaction in the layered 1.87 Ga Soukkio Complex in Mäntsälä, southern Finland

Directory of Open Access Journals (Sweden)

Toni T. Eerola

2002-01-01

Full Text Available The Svecofennian layered Soukkio Complex (1.87 Ga in Mäntsälä, southern Finland, consists of layered tholeiitic gabbro and porphyritic calc-alkaline monzonite, quartz monzonite and granite, mingled together. The gabbro belongs to a group of ten mafic-ultramafic intrusions of Mäntsälä, part of the 150 km long and 20 km wide, linear, E-W trending Hyvinkää–Mäntsälä Gabbroic Belt(HMGB, representing syn-collisional magmatism. Structures and textures related to magma mingling and mixing occur in a 1–2 km wide zone around Lake Kilpijärvi, located at the center of the Soukkio Complex. The complex is compositionally stratified and consists of four zones:its base, found at the Western Zone, is a dynamically layered gabbro. The followingtonalite is probably a result of magma mixing. Felsic amoeboid layers and pipes, alternating with or cutting the fine-grained gabbro in the Central-Western Zone, resemble those of mafic-silicic layered intrusions in general. Mafic magmatic enclaves (MMEs and pillows form the South-Central Zone and disrupted synplutonic mafic dykes or sheets intruded the granite in the Eastern Zone. The MMEs and disrupted synplutonic mafic dykes or sheets show cuspate and chilled margins against the felsic host, quartz ocelli, corroded K-feldspar xenocrysts with or without plagioclase mantles, and acicular apatite, all typical features of magma mingling and mixing. Mixing is suggested by intermediate composition of MMEs between granitoid and gabbro, as well as by their partly linear trends in some Harker diagrams. REE composition of the MMEs is similar to that of the Soukkio Gabbro, as expected for granite hosted MMEs. The model proposed for evolution of the Soukkio Complex involves intrusion of mafic magma into the crust, causing its partial melting. This generated granitic magma above the mafic chamber. Injections of mafic magma invaded the felsic chamber and those magmas interacted mainly by intermingling. Mingling and

Influences of different oxidants on the characteristics of HfAlOx films deposited by atomic layer deposition

International Nuclear Information System (INIS)

Fan Ji-Bin; Liu Hong-Xia; Ma Fei; Zhuo Qing-Qing; Hao Yue

2013-01-01

A comparative study of two kinds of oxidants (H 2 O and O 3 ) with the combinations of two metal precursors [trimethylaluminum (TMA) and tetrakis(ethylmethylamino) hafnium (TEMAH)] for atomic layer deposition (ALD) hafnium aluminum oxide (HfAlO x ) films is carried out. The effects of different oxidants on the physical properties and electrical characteristics of HfAlO x films are studied. The preliminary testing results indicate that the impurity level of HfAlO x films grown with both H 2 O and O 3 used as oxidants can be well controlled, which has significant effects on the dielectric constant, valence band, electrical properties, and stability of HfAlO x film. Additional thermal annealing effects on the properties of HfAlO x films grown with different oxidants are also investigated. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Low-temperature fabrication of an HfO2 passivation layer for amorphous indium-gallium-zinc oxide thin film transistors using a solution process.

Science.gov (United States)

Hong, Seonghwan; Park, Sung Pyo; Kim, Yeong-Gyu; Kang, Byung Ha; Na, Jae Won; Kim, Hyun Jae

2017-11-24

We report low-temperature solution processing of hafnium oxide (HfO 2 ) passivation layers for amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). At 150 °C, the hafnium chloride (HfCl 4 ) precursor readily hydrolyzed in deionized (DI) water and transformed into an HfO 2 film. The fabricated HfO 2 passivation layer prevented any interaction between the back surface of an a-IGZO TFT and ambient gas. Moreover, diffused Hf 4+ in the back-channel layer of the a-IGZO TFT reduced the oxygen vacancy, which is the origin of the electrical instability in a-IGZO TFTs. Consequently, the a-IGZO TFT with the HfO 2 passivation layer exhibited improved stability, showing a decrease in the threshold voltage shift from 4.83 to 1.68 V under a positive bias stress test conducted over 10,000 s.

Thermodynamics of HfCl/sub 4/-KCl molten mixtures containing HfCl/sub 4/ up to 33. 3 mol. per cent

Energy Technology Data Exchange (ETDEWEB)

Smirnov, M V; Salyulev, A B; Kudyakov, V Ya [AN SSSR, Sverdlovsk. Inst. Ehlektrokhimii

1980-05-01

Based on measurements of saturated vapour pressure in components of melted mixtures of HfCl/sub 4/-KCl, depending on temperature and concentration, calculated are the results of changes in activity coefficients of hafnium tetrachloride and potassium chloride on transition from diluted solutions, where the Henry law is met, to those concentrated where the law is disobeyed. Growth in the activity coefficient of HfCl/sub 4/ is due to dissociation of complex groups of HfCl/sub 6//sup 2 -/ into complexes with a lesser number of ligands and decreasing relative binding energy of Hf/sup 4 +/-Cl/sup -/ there. In this case, marked changes take place in partial enthalpy and entropy of hafnium tetrachloride mixing. Similar dependences are observed for potassium chloride, but they are expressed considerably weaker. Evaporation enthalpy and entropy are calculated for HfCl/sub 4/ and KCl monomers from their melted mixtures of various concentrations.

Thermodynamics of HfCl4-KCl molten mixtures containing HfCl4 up to 33.3 mol. per cent

International Nuclear Information System (INIS)

Smirnov, M.V.; Salyulev, A.B.; Kudyakov, V.Ya.

1980-01-01

Based on measurements of saturated vapour pressure in components of melted mixtures of HfCl 4 -KCl, depending on temperature and concentration, calculated are the results of changes in activity coefficients of hafnium tetrachloride and potassium chloride on transition from diluted solutions, where the Henry law is met, to those concentrated where the law is disobeyed. Growth in the activity coefficient of HfCl 4 is due to dissociation of complex groups of HfCl 6 2- into complexes with a lesser number of ligands and decreasing relative binding energy of Hf 4+ -Cl - there. In this case, marked changes take place in partial enthalpy and entropy of hafnium tetrachloride mixing. Similar dependences are observed for potassium chloride, but they are expressed considerably weaker. Evaporation enthalpy and entropy are calculated for HfCl 4 and KCl monomers from their melted mixtures of various concentrations

The high-spin {sup 178m2}Hf isomer: production, chemical and isotopic separations, gamma spectrometry and internal conversion electrons spectrometry; L`isomere de haut spin {sup 178m2}Hf: production, separations chimiques et isotopiques, spectrometrie gamma et spectrometrie d`electrons de conversion interne

Energy Technology Data Exchange (ETDEWEB)

Kim, J B

1993-10-13

The high-spin isometric state of the nucleus 178Hf is a challenge for new and exotic nuclear physics studies. With its long half-life of 31 years, the production of a reasonable micro-weight quantity, with an isometric to ground state ratio as high as 5 per cent, is now regularly performed by intensive irradiations of ytterbium targets with helium ions of 36 MeV. Using sur-enriched, at 99,998 per cent, ytterbium 176 that we have prepared at the PARIS mass separator, the isomer purity has been improved. Targets of such material but also of enriched stable isotopes of hafnium have been prepared by electro-spraying of methanolic and acetic solutions. By inelastic diffusion of protons and deuton on these targets, the energy of the first state of the rotation band built on the isomer has been measured. Isotopic separations of the isomer have been performed, with a yield greater than 20 per cent, by the use of isotopically pure hafnium 176 as carrier. The separated beam of the mass 178 allowed to record the complete hyperfine spectrum of the isomer and to measure, for the first time, the magnetic dipole moment and the electric quadrupole moment. Isomer targets, implanted in various materials like copper, iron and hafnium monocrystal, provide the opportunity to accurately measure gamma and internal conversion decay of this nuclei and so to precise the multipolarity mixing of all transitions from K=16{sup +} to K=8{sup -}. (author). 49 refs., 47 figs., 11 tabs.

m manjula

Indian Academy of Sciences (India)

Home; Journals; Bulletin of Materials Science. M MANJULA. Articles written in Bulletin of Materials Science. Volume 41 Issue 1 February 2018 pp 19. Elastic and thermodynamic properties of zirconium- and hafnium-doped Rh$_3$V intermetallic compounds: potential aerospace material · M MANJULA M SUNDARESWARI ...

Structure of Zr-Hf alloys

International Nuclear Information System (INIS)

Dobromyslov, A.V.; Taluts, N.I.

1991-01-01

Structure of quenched zirconium-hafnium alloy system containing up to 2.5 at. % was studied. Existence of three morphological forms of α-phase was presented: lath, twinned, laminated. Twinning plane in the system was identified. Formation model of packet structure of lath martensite was suggested

Nanomechanical properties of hafnium nitride coating

International Nuclear Information System (INIS)

Chen Yao; Laha, Tapas; Balani, Kantesh; Agarwal, Arvind

2008-01-01

Nanomechanical properties of plasma-sprayed HfN coating with and without hot isostatic pressing (HIP) treatment were evaluated using nanoindentation. For HIPed HfN coating, the elastic modulus (E) and yield strength increase whereas the hardness (H), H/E ratio and fraction of the elastic work decrease. HIPed HfN coating shows a larger pile-up around the indent as compared to as-sprayed HfN. HIPing causes densification and improvement in inter-splat bonding which subsequently lead to increase in nanomechanical properties

Coexistence of different charge states in Ta-doped monoclinic HfO2: Theoretical and experimental approaches

DEFF Research Database (Denmark)

Taylor, M.A.; Alonso, R.E.; Errico, L.A.

2010-01-01

A combination of experiments and ab initio quantum-mechanical calculations has been applied to examine hyperfine interactions in Ta-doped hafnium dioxide. Although the properties of monoclinic HfO2 have been the subject of several earlier studies, some aspects remain open. In particular, time dif...

Temperature Effects on a-IGZO Thin Film Transistors Using HfO2 Gate Dielectric Material

Directory of Open Access Journals (Sweden)

Yu-Hsien Lin

2014-01-01

Full Text Available This study investigated the temperature effect on amorphous indium gallium zinc oxide (a-IGZO thin film transistors (TFTs using hafnium oxide (HfO2 gate dielectric material. HfO2 is an attractive candidate as a high-κ dielectric material for gate oxide because it has great potential to exhibit superior electrical properties with a high drive current. In the process of integrating the gate dielectric and IGZO thin film, postannealing treatment is an essential process for completing the chemical reaction of the IGZO thin film and enhancing the gate oxide quality to adjust the electrical characteristics of the TFTs. However, the hafnium atom diffused the IGZO thin film, causing interface roughness because of the stability of the HfO2 dielectric thin film during high-temperature annealing. In this study, the annealing temperature was optimized at 200°C for a HfO2 gate dielectric TFT exhibiting high mobility, a high ION/IOFF ratio, low IOFF current, and excellent subthreshold swing (SS.

Pressure induced phase transition in HfTiO4

International Nuclear Information System (INIS)

Mishra, A.K.; Garg, Nandini; Sharma, Surinder M.; Panneerselvam, G.

2012-01-01

Hafnium titanate is a low thermal expansion ceramic with a very good absorption cross section for thermal neutrons and a high refractoriness, thus making it a desirable nuclear material. At ambient conditions it crystallizes with the orthorhombic structure (space group Pbcn). The material properties of this ceramic have been studied as a function of temperature. However, apart from a lone shock study several decades ago there is no study at static high pressure on this compound. Since this ceramic is used as control rods in nuclear reactors it is important to understand its phase stability at different thermodynamic conditions. Therefore to understand the high pressure behaviour of hafnium titanate we have carried out diamond anvil cell based X-ray diffraction studies up to ∼20 GPa. The studies on this ceramic show that its structure is stable till 11 GPa. However, at ∼11.7 GPa appearance of new diffraction peaks indicate that it undergoes a structural phase transition to a low symmetry structure

27 CFR 44.187 - Shipping containers.

Science.gov (United States)

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 2 2010-04-01 2010-04-01 false Shipping containers. 44... Shipping containers. Each shipping case, crate, or other container in which tobacco products, or cigarette... same containers in which they were received from the factory. (72 Stat. 1418, as amended; 26 U.S.C...

187 AGRICULTURAL GROWTH AND EXTERNAL DEBT ...

African Journals Online (AJOL)

indices painted a dark picture at the middle stage of Nigerian economy. ... 1980, the oil boom that drafted away government's attention from agriculture in early 70's ..... projects, thus creating room for some selective prestigious projects of ...

Publications | Page 187 | IDRC - International Development ...

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Managing health risks on small dairy farms in Kenya ... Dietary salt reduction and cardiovascular disease rates in India : a mathematical model (open access) ... Quantifying the direct and indirect effects of Dissolved Organic Matter (DOM) on ...

Page | 187 DISPLACEMENT AND ENVIRONMENTAL PROTECTION

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Fr. Ikenga

development remain one of the greatest concerns of human beings globally.4. This urbanization which most often result in conflicts, ethnic violence, communal rife and clashes, and incessant tussle for natural and artificial resources, has also contributed to the displacement of persons. * By Obinna MBANUGO, LLM, BL, ...

FCJ-187 The Droning of Experience

Directory of Open Access Journals (Sweden)

Mark Andrejevic

2015-08-01

Full Text Available The figure of the drone is invoked as a contemporary avatar for the logics of distributed networking at a distance, automated sense-making and automated response associated with interactive platforms more generally. The case of affective apps is forwarded as an example of the generalised logic of ‘droning’ in the register of control via the modulation of affect. The argument focuses on examples of data mining in the affective frontier: apps that generate data about affective states in order to more effectively categorise and target users. The conclusion argues for a reconfigured approach to questions of alienation as one way of critiquing drone infrastructures and the logics of droning.

32 CFR 187.6 - Information requirements.

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2010-07-01

... direct exports by the Department of Defense of defense articles and services to foreign governments and... providing to a foreign nation a nuclear production or utilization facility, as defined in the Atomic Energy... utility of the environmental analysis and the need for an in-depth review diminishes as DoD's role and...

49 CFR 572.187 - Lumbar spine.

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2010-10-01

...-time history of the pendulum falls inside the corridor determined by the upper and lower boundaries... response from time-zero. (2) The maximum rotation in the lateral direction of the reference plane of the...

Mesocrystals luminescent BaZrHfO{sub 3} synthesized via hydrothermal process assisted by microwave

Energy Technology Data Exchange (ETDEWEB)

Fassbender, Rafael Uarth, E-mail: uarth.fisica@gmail.com

2016-07-01

Full text: The Barium Zirconate (BaZrO{sub 3}), is a ceramic oxide belonging to the functional group of perovskites (ABO{sub 3}), this compound can be doped with hafniun (Hf) in solid solution by microwave assisted hydrothermal method (MAH) radioluminescent increases their properties. This method allows to obtain barium zirconate at low temperature as 140 deg C and short times as 160 minutes. The choice of Hafnium (Hf) as a dopant is based on its similarity with Zirconium (Zr), another good reason for this choice is that the Hafnium has intrinsic luminescent characteristics. In general, radioluminescent materials have high density and high atomic mass (atomic number of Hafnium is 72), thereby facilitating the absorption of ionizing radiation to convert it into visible light, this characteristic is strongly dependent on the morphology and especially the electronic structure of (BaZrO{sub 3}). This work consisted in production of barium zirconate powders doped 1-2-4-8-16% (Hf) using (MAH) method. For the characterization of the powders was employed methods : a) X-ray diffraction, b) Raman Spectroscopy, c) Xanes, d) photoluminescence spectroscopy. After the electronic and structural characterization the powders were introduced in a polymeric resin (nylon-BZO), one new characterizations will be performed to validate the results obtained in the production of films to the results already obtained for the powders. We conclude so far, that the powders-doped with 16% Hf has an intense luminescent emission compared to the powders with less concentration of Hf. The small structural change that causes the Hf in (BZO) is considered as a secondary factory. (author)

Catalytic activity of metall-like carbides in carbon oxide oxidation reaction

International Nuclear Information System (INIS)

Kharlamov, A.I.; Kosolapova, T.Ya.; Rafal, A.N.; Kirillova, N.V.

1980-01-01

Kinetics of carbon oxide oxidation upon carbides of hafnium, niobium, tantalum, molybdenum, zirconium and chromium is studied. Probable mechanism of the catalysts action is suggested. The established character of the change of the carbide catalytic activity is explained by the change of d-electron contribution to the metal-metal interaction

George de Hevesy (1885 - 1966), founder of radioanalytical chemistry

International Nuclear Information System (INIS)

Niese, S.

2006-01-01

George de Hevesy has founded Radioanalytical Chemistry and Nuclear Medicine, discovered the element hafnium and first separated stable isotopes. For all these different important achievements he was nominated for the Nobel Prize. On occasion of his discovery of activation analysis 70 years ago his life and work will be illustrated. (author)

A Coincidental Discovery of a New Stable Variant (Hb Hachioji or HBB: c.187C>T) in a Patient with Chronic Hemolytic Anemia of Unexplained Origin.

Science.gov (United States)

Mella, Ferania; Yamashiro, Yasuhiro; Adhiyanto, Chris; Tanaka, Tatehiko; Nitta, Takenori; Amao, Yuki; Kimoto, Masafumi

2018-01-01

We report a new hemoglobin (Hb) variant, Hb Hachioji (HBB: c.187C>T), which was detected in a 32-year-old male with hemolytic anemia. The proband had undergone splenectomy in his childhood after being diagnosed with hereditary spherocytosis (HS) with no clinical improvement. A recent study showed that Heinz bodies were frequently observed in his red cells, however, no abnormal band was separated by isoelectric focusing (IEF), and the isopropanol (instability) test was negative. Direct sequencing revealed that the proband was a heterozygous carrier of a novel mutation (GCT>GTT) at codon 62 of the β-globin gene, leading to an alanine to valine substitution. This variant was named Hb Hachioji. Characterization at the mRNA level by cDNA sequencing detected β Hachioji mRNA, as well as β A mRNA. Subsequently, study of the proband's family indicated that his father was a carrier of this Hb variant, although unexpectedly, the father was asymptomatic and clinically healthy. Oxygen affinity measurement of total Hb showed no alteration in the P 50 and oxygen equilibrium curve. The presence of Hb Hachioji was confirmed by mass spectrometry (MS). Hb Hachioji comprised approximately 50.0% of the total Hb and was a stable variant. The phenotypic discrepancy between these two carriers suggests that Hb Hachioji may not be associated with the hemolytic involvement in the proband. P4.2Nippon, which is the primary cause of most cases of Japanese HS, was absent in the proband's parents. The coexistence of glucose-6-phosphate dehydrogenase (G6PD) deficiency was ruled out. Thus, the cause of hemolytic involvement in this patient remains unclear.

Dicty_cDB: [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available VF (Link to library) VFC187 (Link to dictyBase) - - - Contig-U12289-1 VFC187P (Link... to Original site) VFC187F 411 VFC187Z 678 VFC187P 1089 - - Show VFC187 Library VF (Link to library) Clone ID VFC187 (Link to dict...yBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig Contig-U12289-1 Original site URL http://dict... N AC117176 |AC117176.2 Dictyostelium discoideum chromosome 2 map 5018074-5200947... strain AX4, complete sequence. 36 0.008 12 AC114263 |AC114263.2 Dictyostelium discoideum chromosome 2 map 2

Global, Regional, and National Consumption of Sugar-Sweetened Beverages, Fruit Juices, and Milk: A Systematic Assessment of Beverage Intake in 187 Countries

Science.gov (United States)

Khatibzadeh, Shahab; Shi, Peilin; Lim, Stephen; Andrews, Kathryn G.; Engell, Rebecca E.; Ezzati, Majid; Mozaffarian, Dariush

2015-01-01

Background Sugar-sweetened beverages (SSBs), fruit juice, and milk are components of diet of major public health interest. To-date, assessment of their global distributions and health impacts has been limited by insufficient comparable and reliable data by country, age, and sex. Objective To quantify global, regional, and national levels of SSB, fruit juice, and milk intake by age and sex in adults over age 20 in 2010. Methods We identified, obtained, and assessed data on intakes of these beverages in adults, by age and sex, from 193 nationally- or subnationally-representative diet surveys worldwide, representing over half the world’s population. We also extracted data relevant to milk, fruit juice, and SSB availability for 187 countries from annual food balance information collected by the United Nations Food and Agriculture Organization. We developed a hierarchical Bayesian model to account for measurement incomparability, study representativeness, and sampling and modeling uncertainty, and to combine and harmonize nationally representative dietary survey data and food availability data. Results In 2010, global average intakes were 0.58 (95%UI: 0.37, 0.89) 8 oz servings/day for SSBs, 0.16 (0.10, 0.26) for fruit juice, and 0.57 (0.39, 0.83) for milk. There was significant heterogeneity in consumption of each beverage by region and age. Intakes of SSB were highest in the Caribbean (1.9 servings/day; 1.2, 3.0); fruit juice consumption was highest in Australia and New Zealand (0.66; 0.35, 1.13); and milk intake was highest in Central Latin America and parts of Europe (1.06; 0.68, 1.59). Intakes of all three beverages were lowest in East Asia and Oceania. Globally and within regions, SSB consumption was highest in younger adults; fruit juice consumption showed little relation with age; and milk intakes were highest in older adults. Conclusions Our analysis highlights the enormous spectrum of beverage intakes worldwide, by country, age, and sex. These data are

Pramana – Journal of Physics | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Pramana – Journal of Physics; Volume 68; Issue 1 ... pp 1-19 Research Articles ... Maximum yield and best quality CNTs were obtained using H2 as the carrier gas. ... Electronic structure of hafnium: A Compton profile study ... Odd–even effect in fragment angular momentum in low-energy fission of actinides.

Nanomechanical study of amorphous and polycrystalline ALD HfO2 thin films

Science.gov (United States)

K. Tapily; J.E. Jakes; D. Gu; H. Baumgart; A.A. Elmustafa

2011-01-01

Thin films of hafnium oxide (HfO2) were deposited by atomic layer deposition (ALD). The structural properties of the deposited films were characterised by transmission electron microscopy (TEM) and X-ray diffraction (XRD). We investigated the effect of phase transformations induced by thermal treatments on the mechanical properties of ALD HfO

Neutron activation analysis measurements of sub micron aerosol deposition onto a cylinder energized with an alternating electric field

Energy Technology Data Exchange (ETDEWEB)

Fila, M S [Toronto Univ., ON (Canada). Dept. of Chemical Engineering and Applied Chemistry

1994-12-31

Experimental measurements of aerosol deposition onto a cylinder energized with a 60 Hz electric field were conducted using a neutron activation analysis technique with a hafnium salt aerosol. The measured collection efficiencies were compared to theoretical expressions based on an electrostatic collection mechanism and fair agreement was found. (author). 5 refs., 1 tab., 2 figs.

Viscosity measurements of molten refractory metals using an electrostatic levitator

International Nuclear Information System (INIS)

Ishikawa, Takehiko; Paradis, Paul-François; Okada, Junpei T; Watanabe, Yuki

2012-01-01

Viscosities of several refractory metals (titanium, nickel, zirconium, niobium, ruthenium, rhodium, hafnium, iridium and platinum) and terbium have been measured by the oscillation drop method with an improved procedure. The measured data were less scattered than our previous measurements. Viscosities at their melting temperatures showed good agreement with literature values and some predicted values. (paper)

Submicrometric gratings fabrication from photosensitive organo-silica-hafnia thin films elaborated by sol-gel processing

Energy Technology Data Exchange (ETDEWEB)

Franc, Janyce [Universite de Lyon, F-42023 Saint-Etienne (France); CNRS, UMR 5516, Laboratoire Hubert Curien, 42023 Saint-Etienne (France); Universite de Saint-Etienne, Jean-Monnet, F-42023 Saint-Etienne (France); Barnier, Vincent, E-mail: barnier@emse.fr [Ecole Nationale Superieure des Mines, SMS-EMSE, CNRS:UMR 5146, LCG, F-42023 Saint-Etienne (France); Vocanson, Francis, E-mail: francis.vocanson@univ-st-etienne.fr [Universite de Lyon, F-42023 Saint-Etienne (France); CNRS, UMR 5516, Laboratoire Hubert Curien, 42023 Saint-Etienne (France); Universite de Saint-Etienne, Jean-Monnet, F-42023 Saint-Etienne (France); Gamet, Emilie; Lesage, Maryline [Universite de Lyon, F-42023 Saint-Etienne (France); CNRS, UMR 5516, Laboratoire Hubert Curien, 42023 Saint-Etienne (France); Universite de Saint-Etienne, Jean-Monnet, F-42023 Saint-Etienne (France); Jamon, Damien [Universite de Lyon, F-42023 Saint-Etienne (France); Laboratoire Claude Chappe, Telecom Saint-Etienne, 42000 Saint-Etienne Cedex 2 (France); Universite de Saint-Etienne, Jean-Monnet, F-42023 Saint-Etienne (France); Jourlin, Yves [Universite de Lyon, F-42023 Saint-Etienne (France); CNRS, UMR 5516, Laboratoire Hubert Curien, 42023 Saint-Etienne (France); Universite de Saint-Etienne, Jean-Monnet, F-42023 Saint-Etienne (France)

2012-07-31

The aim of this study is the elaboration of a high index sol-gel material in order to prepare submicrometric grating. The gratings were obtained after few seconds of UV exposure in one step using an organically modified silica-hafnia matrix. The chemical composition of thin films after UV and annealing treatments were studied using Fourier Transform Infrared Spectroscopy and X-Ray Photoelectron Spectroscopy. The study of optical properties revealed that the annealed films are transparent from 200 to 1000 nm and have a refractive index from 1.550 to 1.701 depending on the hafnium concentration. - Highlights: Black-Right-Pointing-Pointer Silica-hafnia matrix with high refractive index was prepared using sol-gel process. Black-Right-Pointing-Pointer Organic and inorganic networks formation of thin films was investigated. Black-Right-Pointing-Pointer Optical properties are influenced by annealing treatment and initial hafnium amount. Black-Right-Pointing-Pointer The use of high Si:Hf molar ratio can lead to a loss transmittance below 300 nm. Black-Right-Pointing-Pointer Submicrometric grating period can be prepared using a holographic method.

Dissolution kinetics of small amounts of oxygen in tantalum alloy T-111 and internal oxide displacement reactions during annealing

Science.gov (United States)

Stecura, S.

1976-01-01

Oxygen was added to T-111 (Ta-8W-2Hf, wt. %) at 820 and 990 C at an oxygen pressure of about 0.0003 torr. The technique employed permitted predetermined and reproducible doping of T-111 up to 3.0 at. % oxygen. Based on the temperature dependence of the doping reaction, it is concluded that the initial rates of oxygen pickup are probably controlled by solution of oxygen into the T-111 lattice. Although hafnium oxides are more stable than those of tantalum or tungsten, analyses of extracted residues indicate that the latter oxides predominate in the as-doped specimens, presumably because of the higher concentrations of tantalum and tungsten in the alloy. However, high-temperature annealing promotes gettering of dissolved oxygen and of other oxides to form hafnium oxides. Small amounts of tantalum and tungsten oxides were still present after high-temperature annealing. Tungsten oxide (WO3) volatilizes slightly from the surface of T-111 at 990 C. The vaporization of WO3 has no apparent affect on the doping reaction.

Temperature dependence of the work function of ruthenium-based gate electrodes

International Nuclear Information System (INIS)

Alshareef, H.N.; Wen, H.C.; Luan, H.F.; Choi, K.; Harris, H.R.; Senzaki, Y.; Majhi, P.; Lee, B.H.; Foran, B.; Lian, G.

2006-01-01

The effect of device fabrication temperature on the work function of ruthenium (Ru) metal gate and its bilayers was investigated. The work function shows strong temperature dependence when Ru electrodes are deposited on silicon oxide, SiO 2 , but not on hafnium silicates (HfSiO x ). Specifically, the work function of Ru on SiO 2 increased from 4.5 eV at 500 deg. C to 5.0 eV at 700 deg. C. On further annealing to 900 deg. C or higher, the work function dropped to about 4.4 eV. In the case of HfSiO x , the work function of Ru changed by less than 100 mV over the same temperature range. Identical temperature dependence was observed using hafnium (Hf)/Ru and tantalum (Ta)/Ru bilayers. However, the peak values of the work function decreased with increasing Hf/Ru and Ta/Ru thickness ratios. Materials analysis suggests that these trends are driven by interactions at the Ru metal gate-dielectric interface

Experience of CR and RCCA operation in Ukrainian WWER-1000: Aspects of reliability, safety and economic efficiency

International Nuclear Information System (INIS)

Afanasyev, A.

2000-01-01

The next topics are represented in the paper: A brief history of WWER-1000 control rod (CR) and WWER-1000 rod cluster control assembly (RCCA) design; Evolution of WWER-1000 CR manufacturing technology and design; Experience of RCCA operation; Lifetime extension of WWER-1000 boron carbide CR; WWER-1000 reactor core operation problems due to partial RCCA insertion; Designing and licensing procedures and first operational experience of WWER-1000 RCCA (CR) with a combined absorber 'boron carbide-hafnium' and a chromium-nickel alloy cladding. The main conclusions are: Fuel assembly (FA) bow is the main reason of partial RCCA insertion during reactor core operation. However, the use of the RCCA and its driver bar with increased dead load, alongside with other measures, allow to reduce the probability of incomplete RCCA insertion; The materials used in CRs of RCCA in existing reactor operating modes have been working reliably; The use of hafnium under an appropriate price policy can give certain economic advantages for the Ukrainian NPPs, however, additional research is needed in order to confirm the specific CR physical characteristics and reliability. (author)

Luminescence of Ce doped oxygen crystalline compounds based on Hf and Ba

CERN Document Server

Borisevich, A E; Lecoq, P

2003-01-01

The luminescence properties of the Ce-doped hafnium and barium compounds have been investigated to determine their potential as heavy scintillation materials. Compounds have been prepared by solid state synthesis. All of them have shown a bright luminescence attributed to trivalent cerium. Emission bands are peaked in the 425-475nm spectral region at room temperature.

Activation Analysis of Aluminium

Energy Technology Data Exchange (ETDEWEB)

Brune, Dag

1961-01-15

An analysis of pure aluminium alloyed with magnesium was per- formed by means of gamma spectrometry , Chemical separations were not employed. The isotopes to be determined were obtained in conditions of optimum activity by suitably choosing the time of irradiation and decay. The following elements were detected and measured quantitatively: Iron, zinc, copper, gallium, manganese, chromium, scandium and hafnium.

Neutron-Activation Analysis of Biological Material with High Radiation Levels

Energy Technology Data Exchange (ETDEWEB)

Samsahl, K

1966-09-15

A method has been developed for the chemical separation and subsequent gamma-spectrometric analysis of the alkali metals, the alkaline earths, the rare earths, chromium, hafnium, lanthanum, manganese, phosphorus, scandium and silver in neutron-activated biological material. The separation steps, being fully automatic, are based on a combination of ion-exchange and partition chromatography and require 40 min.

Process and operating device for an apparatus using a running liquid film and application to separation of Zr and Hf tetrachlorides

International Nuclear Information System (INIS)

Brun, R.

1989-01-01

A process is claimed allowing to maintain a thin film in a running film exchanger, by increasing the flow rate for a short time to establish a film all over the surface. Application is made to continuous condensation of zirconium and hafnium tetrachlorides, from the separation column, by absorption in a liquid solvent made of potassium chloroaluminate [fr

Neutron-Activation Analysis of Biological Material with High Radiation Levels

International Nuclear Information System (INIS)

Samsahl, K.

1966-09-01

A method has been developed for the chemical separation and subsequent gamma-spectrometric analysis of the alkali metals, the alkaline earths, the rare earths, chromium, hafnium, lanthanum, manganese, phosphorus, scandium and silver in neutron-activated biological material. The separation steps, being fully automatic, are based on a combination of ion-exchange and partition chromatography and require 40 min

Passive behaviour of zirconium, hafnium and niobium

International Nuclear Information System (INIS)

Hornkjoel, S.

1990-01-01

The paper deals mainly with the results of stationary and transient polarization measurements together with capacitance measurements on passive electrodes of Zr, Hf and Nb over the entire pH-scale. The passive current densities are exstremely low, and essentially both pH and potential independent, exept for Nb at high pH. The extrapolated potential of zero inverse capacitance seems to be different from the extrapolated potential of zero film thickness for Zr and Hf, but not for Nb. The potential versus time curves at constant current show a downwards bending for Zr and Hf. It is shown that the pitting potentials of Zr and Hf are dependent of the concentration of halide ions and the type of halide ion, but not on pH. It is also shown that the pitting induction is second-order stimulated by chloride ions and first-order hindered by sulphate ions. Results from electron transfer reactions on passive niobium are reported. 9 refs

PEMISAHAN Zr – Hf SECARA SINAMBUNG MENGGUNAKAN MIXER SETTLER

Directory of Open Access Journals (Sweden)

Dwi Biyantoro

2017-01-01

Full Text Available ABSTRAK PEMISAHAN Zr – Hf SECARA SINAMBUNG MENGGUNAKANMIXER SETTLER. Telah dilakukan pemisahanZr – Hf secara sinambung menggunakan pengaduk pengenap (mixer settler 16 stage. Larutan umpan adalah zirkon nitrat dengan kadar Zr = 30786 ppm dan Hf = 499 ppm. Ekstraktan dipakai adalah solven 60 % TBP dalam kerosen dan larutan scrubbingyang dipakai adalah asam nitrat 1 M. Umpan masuk pada stageke 5 dikontakkan secara berlawanan arah dengan solven masuk pada stage ke 16 dan larutan scrubbing masuk pada stage ke 1. Tujuan penelitian ini adalah memisahkan unsur Zr dan Hf dari hasil olah pasir zirkon menggunakan solven TBP dengan alat mixer settler16 stage. Analisis umpan dan hasil proses pemisahan untuk zirkonium (Zr dilakukan dengan menggunakan alat pendar sinar-X, sedangkananalisis unsur hafnium (Hf menggunakan Analisis Pengaktifan Neutron (APN. Parameter penelitian dilakukan dengan variasi keasaman asam nitrat dalam umpan dan variasi waktu pada berbagai laju pengadukan. Hasil penelitian pemisahan unsur Zr dengan Hf diperolehkondisi optimum pada keasaman umpan 4 N HNO3, keseimbangan dicapai setelah 3jam dan laju pengadukan 3300 rpm. Hasil ekstrak  unsur zirkon (Zr diperoleh kadar sebesar 28577 ppm dengan efisiensi 92,76 % serta kadar pengotor hafnium (Hf sebesar 95 ppm. Kata Kunci: pemisahan Zr, Hf, ekstraksi, mixer settler, alat pendar sinar-X, APN. ABSTRACT SEPARATION of Zr - Hf CONTINUOUSLY USE THE MIXER SETTLER. Separation of Zr - Hf continuously using mixer settler 16 stage has been done. The feed solution is zircon nitrate concentration of Zr = 30786 ppm  and Hf = 499 ppm. As the solvent used extractant 60 % TBP in 40 % kerosene. Nitric acid solution used srubbing 1 M. The feed entered into stage to 5 is contacted with solvents direction on the stage to 16 and the scrubbing solution enter the stage to 1. The purpose of this study is to separate Zr and Hf of the results from the process of zircon sand using solvent TBP using 16 stage

10 CFR 26.187 - Substance abuse expert.

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2010-01-01

... licensed or certified employee assistance professional; or (5) An alcohol and drug abuse counselor..., rule changes, and other information about developments in SAE practice pertaining to this part, since... activities must include documented assessment tools to assist in determining that the SAE has learned the...

29 CFR 4.187 - Recovery of underpayments.

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2010-07-01

... Internal Revenue Service levy for unpaid taxes. (See Decisions of the Comptroller General, B-170784... Contract Work Hours and Safety Standards Act, 41 U.S.C. 327, et seq.] disclose a progressive tendency to... have priority over reprocurement costs and tax liens without regard to when the competing claims were...

Search Results | Page 187 | IDRC - International Development ...

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2013-07-01

... a transitional context : Tunisia as example. The limits of "façade feminism" are reflected in the current regime''s rejection of ensuring full equality between men and women. Published date. July 1, 2013. Reports. DEMOCRATIZATION POLITICAL REPRESENTATION GENDER MAINSTREAMING WOMEN'S RIGHTS YOUTH ...

7 CFR 800.187 - Conflicts of interest

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2010-01-01

... transporting or storing grain; the merchandising for nonfarm use of equipment for cleaning, drying, treating, fumigating, or otherwise processing, handling, or storing grain; or the merchandising of grain inspection or...

Improving the reversibility of thermal denaturation and catalytic efficiency of Bacillus licheniformis α-amylase through stabilizing a long loop in domain B.

Directory of Open Access Journals (Sweden)

Zhu Li

Full Text Available The reversibility of thermal denaturation and catalytic efficiency of Bacillus licheniformis α-amylase were improved through site-directed mutagenesis. By using multiple sequence alignment and PoPMuSiC algorithm, Ser187 and Asn188, which located within a long loop in Domain B of Bacillus licheniformis α-amylase, were selected for mutation. In addition, Ala269, which is adjacent to Ser187 and Asn188, was also investigated. Seven mutants carrying the mutations S187D, N188T, N188S, A269K, A269K/S187D, S187D/N188T, and A269K/S187D/N188T were generated and characterized. The most thermostable mutant, A269K/S187D/N188T, exhibited a 9-fold improvement in half-life at 95°C and pH 5.5, compared with that of the wild-type enzyme. Mutant A269K/S187D/N188T also exhibited improved catalytic efficiency. The catalytic efficiency of mutant A269K/S187D/N188T reached 5.87×103±0.17 g·L-1·s-1 at pH 5.5, which is 1.84-fold larger than the corresponding value determined for the wild-type enzyme. Furthermore, the structure analysis showed that immobilization of the loop containing Ser187 and Asn188 plays a significant role in developing the properties of Bacillus licheniformis α-amylase.

Improving the reversibility of thermal denaturation and catalytic efficiency of Bacillus licheniformis α-amylase through stabilizing a long loop in domain B.

Science.gov (United States)

Li, Zhu; Duan, Xuguo; Chen, Sheng; Wu, Jing

2017-01-01

The reversibility of thermal denaturation and catalytic efficiency of Bacillus licheniformis α-amylase were improved through site-directed mutagenesis. By using multiple sequence alignment and PoPMuSiC algorithm, Ser187 and Asn188, which located within a long loop in Domain B of Bacillus licheniformis α-amylase, were selected for mutation. In addition, Ala269, which is adjacent to Ser187 and Asn188, was also investigated. Seven mutants carrying the mutations S187D, N188T, N188S, A269K, A269K/S187D, S187D/N188T, and A269K/S187D/N188T were generated and characterized. The most thermostable mutant, A269K/S187D/N188T, exhibited a 9-fold improvement in half-life at 95°C and pH 5.5, compared with that of the wild-type enzyme. Mutant A269K/S187D/N188T also exhibited improved catalytic efficiency. The catalytic efficiency of mutant A269K/S187D/N188T reached 5.87×103±0.17 g·L-1·s-1 at pH 5.5, which is 1.84-fold larger than the corresponding value determined for the wild-type enzyme. Furthermore, the structure analysis showed that immobilization of the loop containing Ser187 and Asn188 plays a significant role in developing the properties of Bacillus licheniformis α-amylase.

40 CFR 421.333 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Science.gov (United States)

2010-07-01

... 2.387 1.108 Nickel 4.688 3.154 Ammonia (as N) 1,136.000 499.500 (d) SiCl4 purification wet air... air pollution control. BAT Limitations for the Primary Zirconium and Hafnium Subcategory Pollutant or... 0.159 0.074 Nickel 0.312 0.210 Ammonia (as N) 75.710 33.280 (b) Sand chlorination off-gas wet air...

Removal of iron contaminant from zirconium chloride solution

International Nuclear Information System (INIS)

Voit, D.O.

1992-01-01

This patent describes a process for eliminating iron contaminant from an aqueous zirconium chloride solution that has been contaminated with FeCl 3 in a plant in which zirconium and hafnium chloride solutions are separated by a main MINK solvent extraction system and the FeCl 3 is normally removed from the zirconium chloride solution by a secondary MINK solvent extraction system

Artificial Composites for High Temperature Applications; A Review (Composites Artificiels Destines a des Applications a Haute Temperature; Un Expose),

Science.gov (United States)

1987-01-01

ceramic fibres and whiskers including silicon carbide, aluminium oxide, zirconium oxide, hafnium oxide and uranium dioxide, were being considered as...3.1.3 Fabrication Processes.................................. 9 3.1.4 Wire/Matrix Interactions and diffusion barriers ........ 10 3.1.5 Mechanical...20 3.2.1 Fibres, Matrices and Fabrication Processes ............ 20 3.2.2 Fibre/Matrix Interaction and Properties............... 21 3.3 Ductile

Contribution to development of SPNDs for instantaneous and selective measurement of different radiation fields in nuclear reactors; Contribution au developpement de collectrons pour la mesure instantanee et selective des differents champs de rayonnements en reacteurs nucleaires

Energy Technology Data Exchange (ETDEWEB)

Blandin, Christophe [Institut National Polytechnique, 38 - Grenoble (France)

1998-02-20

The objective of this work was conceiving and experimentally optimizing the SPNDs (Self-Powdered Neutron Detector) able to control fast power transients in test reactors and also to cope with requirements of surveillanceand protection of EDF reactors. Thus, different SPND emitters of platinum, gadolinium, hafnium and cobalt were provided according to their nature with sheathing and stainless steel plugs as well as with zirconium over-sheathing in order to render them faster, more selective and adapted for wear checking. Special experimental devices were designed for measuring inside the Siloe reactor the promptness of the signals from SPND, on one hand, and their sensitivity to thermal and epithermal neutrons as well as to gamma rays, on the other hand. The follow-up of power transients in test reactors is ensured by the instantaneous measurement of thermal and epithermal neutron flux as well as of gamma field by means of three special SPND with gadolinium, hafnium and platinum. Also, we have defined the characteristics of a new SPND with cobalt, that delivers a current of unique neutronic origin, able to ensure the surveillance and protection of a power reactor over a period of at least six years.

Contribution to development of SPNDs for instantaneous and selective measurement of different radiation fields in nuclear reactors

International Nuclear Information System (INIS)

Blandin, Christophe

1998-01-01

The objective of this work was conceiving and experimentally optimizing the SPNDs (Self-Powdered Neutron Detector) able to control fast power transients in test reactors and also to cope with requirements of surveillance and protection of EDF reactors. Thus, different SPND emitters of platinum, gadolinium, hafnium and cobalt were provided according to their nature with sheathing and stainless steel plugs as well as with zirconium over-sheathing in order to render them faster, more selective and adapted for wear checking. Special experimental devices were designed for measuring inside the Siloe reactor the promptness of the signals from SPND, on one hand, and their sensitivity to thermal and epithermal neutrons as well as to gamma rays, on the other hand. The follow-up of power transients in test reactors is ensured by the instantaneous measurement of thermal and epithermal neutron flux as well as of gamma field by means of three special SPND with gadolinium, hafnium and platinum. Also, we have defined the characteristics of a new SPND with cobalt, that delivers a current of unique neutronic origin, able to ensure the surveillance and protection of a power reactor over a period of at least six years

Electrical characterisation of ferroelectric field effect transistors based on ferroelectric HfO2 thin films

International Nuclear Information System (INIS)

Yurchuk, Ekaterina

2015-01-01

Ferroelectric field effect transistor (FeFET) memories based on a new type of ferroelectric material (silicon doped hafnium oxide) were studied within the scope of the present work. Utilisation of silicon doped hafnium oxide (Si:HfO 2 ) thin films instead of conventional perovskite ferroelectrics as a functional layer in FeFETs provides compatibility to the CMOS process as well as improved device scalability. The influence of different process parameters on the properties of Si:HfO 2 thin films was analysed in order to gain better insight into the occurrence of ferroelectricity in this system. A subsequent examination of the potential of this material as well as its possible limitations with the respect to the application in non-volatile memories followed. The Si:HfO 2 -based ferroelectric transistors that were fully integrated into the state-of-the-art high-k metal gate CMOS technology were studied in this work for the first time. The memory performance of these devices scaled down to 28 nm gate length was investigated. Special attention was paid to the charge trapping phenomenon shown to significantly affect the device behaviour.

Electrical characterisation of ferroelectric field effect transistors based on ferroelectric HfO{sub 2} thin films

Energy Technology Data Exchange (ETDEWEB)

Yurchuk, Ekaterina

2015-02-06

Ferroelectric field effect transistor (FeFET) memories based on a new type of ferroelectric material (silicon doped hafnium oxide) were studied within the scope of the present work. Utilisation of silicon doped hafnium oxide (Si:HfO{sub 2}) thin films instead of conventional perovskite ferroelectrics as a functional layer in FeFETs provides compatibility to the CMOS process as well as improved device scalability. The influence of different process parameters on the properties of Si:HfO{sub 2} thin films was analysed in order to gain better insight into the occurrence of ferroelectricity in this system. A subsequent examination of the potential of this material as well as its possible limitations with the respect to the application in non-volatile memories followed. The Si:HfO{sub 2}-based ferroelectric transistors that were fully integrated into the state-of-the-art high-k metal gate CMOS technology were studied in this work for the first time. The memory performance of these devices scaled down to 28 nm gate length was investigated. Special attention was paid to the charge trapping phenomenon shown to significantly affect the device behaviour.

Spatial conductivity mapping of unprotected and capped black phosphorus using microwave microscopy

International Nuclear Information System (INIS)

Visser, Pieter J de; Chua, Rebekah; Island, Joshua O; Finkel, Matvey; Katan, Allard J; Thierschmann, Holger; Zant, Herre S J van der; Klapwijk, Teun M

2016-01-01

Thin layers of black phosphorus present an ideal combination of a 2D material with a tunable direct bandgap and high carrier mobility. However the material suffers from degradation in ambient conditions due to an oxidation reaction which involves water, oxygen and light. We have measured the spatial profile of the conductivity on flakes of black phosphorus as a function of time using scanning microwave impedance microscopy. A microwave excitation (3 GHz) allows to image a conducting sample even when covered with a dielectric layer. We observe that on bare black phosphorus, the conductivity changes drastically over the whole surface within a day. We demonstrate that the degradation process is slowed down considerably by covering the material with a 10 nm layer of hafnium oxide. It is stable for more than a week, opening up a route towards stable black phosphorus devices in which the high dielectric constant of hafnium oxide can be exploited. Covering black phosphorus with a 15 nm boron nitride flake changes the degradation process qualitatively, it is dominated by the edges of the flake indicating a diffusive process and happens on the scale of days. (letter)

Morphological Studies of Local Influence of Implants with Coatings Based on Superhard Compounds on Bone Tissue under Conditions of Induced Trauma

Directory of Open Access Journals (Sweden)

Galimzyan KABIROV

2015-07-01

Full Text Available In this paper we analyze the response of bone tissue to a transosseous introduction of implants made of copper (Cu, medical steel 12X18H9T, steel with nitrides of titanium and hafnium coatings (TiN + HfN, as well as steel coated with titanium and zirconium nitrides (TiN + ZrN into the diaphysis of the tibia of experimental rats. The obtained results showed that the restoration of the injured bone and bone marrow in groups with implants made of steel 12X18H9T occurred without the participation of the granulation and cartilaginous tissues, but with implants made of steel coated with titanium and hafnium nitrides (TiN + HfN, this bone recovery also took place in the early term. At the same time, in groups, where the implants were made of copper (Cu, implants were made of steel coated with titanium and zirconium nitrides (TiN + ZrN were used, such phenomena as necrosis, lysis and destruction of the bone were registered and the bone tissue repair went through formation of the cartilaginous tissue.

Neutronic design of pulse operation simulating device for in-pile functional test of fusion blanket by MCNP

Energy Technology Data Exchange (ETDEWEB)

Nagao, Yoshiharu; Nakamichi, Masaru; Kawamura, Hiroshi [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan)

2000-03-01

The pulse operation of a fusion reactor can be simulated in a fission reactor by controlling the neutron flux entering a test section by using a rotating 'hollow cylinder with window' made of hafnium. The rotating cylinder is installed between the test section and the fixed outer neutron absorber cylinder and is also made of hafnium with an opening in the direction to the core center. For gathering engineering data for the tritium breeding blanket such as characteristics of temperature change, tritium release and recovery, etc., it is desirable that the ratio of minimum to maximum thermal neutron fluxes is greater than 1:10. Design calculations were performed for the test assembly which considered local neutronic effects and the mechanical constraints of the device. From the results of these calculations, the ratio of minimum to maximum thermal neutron flux under irradiation would be about 1:10 using a pulse operation simulating device which has a thickness of 6.5 mm and a 150deg window angle for the rotating hollow cylinder and 5.0 mm in thickness of fixed neutron absorber. (author)

Thermal effects on the Raman phonon of few-layer phosphorene

International Nuclear Information System (INIS)

Ling, Zhi-Peng; Ang, Kah-Wee

2015-01-01

Two-dimensional phosphorene is a promising channel material for next generation transistor applications due to its superior carrier transport property. Here, we report the influence of thermal effects on the Raman phonon of few-layer phosphorene formed on hafnium-dioxide (HfO 2 ) high-k dielectric. When annealed at elevated temperatures (up to 200 °C), the phosphorene film was found to exhibit a blue shift in both the out-of-plane (A 1 g ) and in-plane (B 2g and A 2 g ) phonon modes as a result of compressive strain effect. This is attributed to the out-diffusion of hafnium (Hf) atoms from the underlying HfO 2 dielectric, which compresses the phosphorene in both the zigzag and armchair directions. With a further increase in thermal energy beyond 250 °C, strain relaxation within phosphorene eventually took place. When this happens, the phosphorene was unable to retain its intrinsic crystallinity prior to annealing, as evident from the broadening of full-width at half maximum of the Raman phonon. These results provide an important insight into the impact of thermal effects on the structural integrity of phosphorene when integrated with high-k gate dielectric

Preparation of thermoluminescent materials

International Nuclear Information System (INIS)

1976-01-01

Thermoluminescent materials have been found to be suitable for measuring long term exposures to low level ionizing radiation. Oxyhalides of lanthanum, gadolinium and yttrium, including the oxychlorides and oxybromides are activated with terbium and have been found to be most efficient oxygendominated phosphors having thermoradiant efficiencies with excitation by low level ionizing radiation. Thermoluminescence response increases when the previous materials have hafnium and zirconium additives

Dispersion engineering of thick high-Q silicon nitride ring-resonators via atomic layer deposition.

Science.gov (United States)

Riemensberger, Johann; Hartinger, Klaus; Herr, Tobias; Brasch, Victor; Holzwarth, Ronald; Kippenberg, Tobias J

2012-12-03

We demonstrate dispersion engineering of integrated silicon nitride based ring resonators through conformal coating with hafnium dioxide deposited on top of the structures via atomic layer deposition. Both, magnitude and bandwidth of anomalous dispersion can be significantly increased. The results are confirmed by high resolution frequency-comb-assisted-diode-laser spectroscopy and are in very good agreement with the simulated modification of the mode spectrum.

Compositions and methods for providing plants with tolerance to abiotic stress conditions

KAUST Repository

Hirt, Heribert; De Zelicourt, Axel; Saad, Maged

2017-01-01

It has been discovered that the desert endophytic bacterium SA187 SA187 can provide resistance or tolerance to abiotic stress conditions to seeds or plants. Compositions containing SA187 can be used to enhance plant development and yield under

Compositions and methods for providing plants with tolerance to abiotic stress conditions

KAUST Repository

Hirt, Heribert

2017-07-27

It has been discovered that the desert endophytic bacterium SA187 SA187 can provide resistance or tolerance to abiotic stress conditions to seeds or plants. Compositions containing SA187 can be used to enhance plant development and yield under environmental stress conditions.

Comment on “Comparison of the composition of the Tempel 1 ejecta to the dust in Comet C/Hale Bopp 1995 O1 and YSO HD 100546” by C.M. Lisse, K.E. Kraemer, J.A. Nuth III, A. Li, D. Joswiak [2007. Icarus 187, 69 86

Science.gov (United States)

Crovisier, Jacques; Bockelée-Morvan, Dominique

2008-06-01

Lisse et al. [Lisse, C.M., Kraemer, K.E., Nuth III, J.A., Li, A., Joswiak, D., 2007. Icarus 187, 69-86] recently presented a new analysis of an ISO spectrum of Comet C/1995 O1 (Hale-Bopp), from which they claimed the identification of many new dust species. Among them are PAHs, which were not found in our first analysis of the ISO spectra. We present here a re-examination of the ISO observations of Comet Hale-Bopp. From the absence of PAHs features in the 5.25-8.5 μm region, we infer that PAHs are at least twice less abundant than derived by Lisse et al. The carbonate feature at 7.00 μm is marginally present, but lower by a factor 2 to 3 than predicted by the model of Lisse et al.

Hafnium Isotopic Variations in Central Atlantic Intraplate Volcanism

Science.gov (United States)

Geldmacher, J.; Hanan, B. B.; Hoernle, K.; Blichert-Toft, J.

2008-12-01

Although one of the geochemically best investigated volcanic regions on Earth, almost no Hf isotopic data have been published from the broad belt of intraplate seamounts and islands in the East Atlantic between 25° and 36° N. This study presents 176Hf/177Hf ratios from 61 representative samples from the Canary, Selvagen and Madeira Islands and nearby large seamounts, encompassing the full range of different evolutionary stages and geochemical endmembers. The majority of samples have mafic, mainly basaltic compositions with Mg-numbers within or near the range of magmas in equilibrium with mantle olivine (68-75). No correlation was found between Mg-number and 176Hf/177Hf ratios in the data set. In comparison to observed Nd isotope variations published for this volcanic province (6 ɛNd units), 176Hf/177Hf ratios span a larger range (14 ɛHf units). Samples from the Madeira archipelago have the most radiogenic compositions (176Hf/177Hfm= 0.283132-0.283335), widely overlapping the field for central Atlantic N-MORB. They form a relatively narrow, elongated trend (stretching over >6 ɛHf units) between a radiogenic MORB-like endmember and a composition located on the Nd-Hf mantle array. In contrast, all Canary Islands samples plot below the mantle array (176Hf/177Hfm = 0.282943-0.283067) and, despite being from an archipelago that stretches over a much larger geographic area, form a much denser cluster with less compositional variation (~4 ɛHf units). All samples from the seamounts NE of the Canaries, proposed to belong to the same Canary hotspot track (e.g. Geldmacher et al., 2001, JVGR 111; Geldmacher et al., 2005, EPSL 237), fall within the Hf isotopic range of this cluster. The cluster largely overlaps the composition of the proposed common mantle endmember 'C' (Hanan and Graham, 1996, Science 272) but spans a space between a more radiogenic (depleted) composition and a HIMU-type endmember. Although samples of Seine and Unicorn seamounts, attributed to the Madeira hotspot track, show less radiogenic Hf and Nd isotope ratios than Madeira, their isotopic compositions lie along an extension of the Madeira trend in plots of Hf versus Sr, Nd, Pb isotopes. The new Hf isotope ratios confirm the existence of at least two geochemically distinct volcanic provinces (Canary and Madeira) in the East Atlantic as previously proposed.

Hafnium isotope ratios of nine GSJ reference samples

International Nuclear Information System (INIS)

Hanyu, Takeshi; Nakai, Shun'ichi; Tatsuta, Riichiro

2005-01-01

176 Hf/ 177 Hf ratios of nine geochemical reference rocks from the Geological Survey of Japan, together with BIR-1 and BCR-2, were determined using multi-collector inductively coupled plasma mass spectrometry. Our data for BIR-1, BCR-2 and JB-1 are in agreement with those previously reported, demonstrating the appropriateness of the chemical procedure and isotopic measurement employed in this study. The reference rocks have a wide range of 176 Hf/ 177 Hf covering the field defined by various volcanic rocks, such as mid-ocean ridge basalts, ocean island basalts, and subduction related volcanic rocks. They are therefore suitable as rock standards for Hf isotope measurement of geological samples. (author)

Elastic and Thermodynamic Properties of Zirconium and Hafnium ...

Indian Academy of Sciences (India)

65

Here Rh3V is chosen as the parent binary compound and the doping ..... Grüneisen parameter ζ [44] are two key quantities in solid state problems due to their .... The authors wish to thank DRDO (ER & IPR), New Delhi for the financial support.

Hafnium(IV) complexation with oxalate at variable temperatures

Energy Technology Data Exchange (ETDEWEB)

Friend, Mitchell T.; Wall, Nathalie A. [Washington State Univ., Pullmanm, WA (United States). Dept. of Chemistry

2017-08-01

Appropriate management of fission products in the reprocessing of spent nuclear fuel (SNF) is crucial in developing advanced reprocessing schemes. The addition of aqueous phase complexing agents can prevent the co-extraction of these fission products. A solvent extraction technique was used to study the complexation of Hf(IV) - an analog to fission product Zr(IV) - with oxalate at 15, 25, and 35 C in 1 M HClO{sub 4} utilizing a {sup 175+181}Hf radiotracer. The mechanism of the solvent extraction system of 10{sup -5} M Hf(IV) in 1 M HClO{sub 4} to thenoyltrifluoroacetone (TTA) in toluene demonstrated a 4{sup th}-power dependence in both TTA and H{sup +}, with Hf(TTA){sub 4} the only extractable species. The equilibrium constant for the extraction of Hf(TTA){sub 4} was determined to be log K{sub ex}=7.67±0.07 (25±1 C, 1 M HClO{sub 4}). The addition of oxalate to the aqueous phase decreased the distribution ratio, indicating aqueous Hf(IV)-oxalate complex formation. Polynomial fits to the distribution data identified the formation of Hf(ox){sup 2+} and Hf(ox){sub 2(aq)} and their stability constants were measured at 15, 25, and 35 C in 1 M HClO{sub 4}. van't Hoff analysis was used to calculate Δ{sub r}G, Δ{sub r}H, and Δ{sub r}S for these species. Stability constants were observed to increase at higher temperature, an indication that Hf(IV)-oxalate complexation is endothermic and driven by entropy.

Electric field cycling behavior of ferroelectric hafnium oxide.

Science.gov (United States)

Schenk, Tony; Schroeder, Uwe; Pešić, Milan; Popovici, Mihaela; Pershin, Yuriy V; Mikolajick, Thomas

2014-11-26

HfO2 based ferroelectrics are lead-free, simple binary oxides with nonperovskite structure and low permittivity. They just recently started attracting attention of theoretical groups in the fields of ferroelectric memories and electrostatic supercapacitors. A modified approach of harmonic analysis is introduced for temperature-dependent studies of the field cycling behavior and the underlying defect mechanisms. Activation energies for wake-up and fatigue are extracted. Notably, all values are about 100 meV, which is 1 order of magnitude lower than for conventional ferroelectrics like lead zirconate titanate (PZT). This difference is mainly atttributed to the one to two orders of magnitude higher electric fields used for cycling and to the different surface to volume ratios between the 10 nm thin films in this study and the bulk samples of former measurements or simulations. Moreover, a new, analog-like split-up effect of switching peaks by field cycling is discovered and is explained by a network model based on memcapacitive behavior as a result of defect redistribution.

Electronic structure of hafnium: A Compton profile study

Indian Academy of Sciences (India)

To extract the true Compton profile from the raw data, the raw data were cor- rected for ... For the present sample and experimental conditions, the contribution of .... are in better agreement with the simple renormalized free atom calculations for.

Neutron Detection Utilizing Gadolinium Doped Hafnium Oxide Films

National Research Council Canada - National Science Library

Blasy, Bryan D

2008-01-01

... retains monoclinic local symmetery for all levels of doping. Current as a function of voltage experiments identified the films as having poor diode characteristics with high leakage current in the forward bias region...

Elastic and thermodynamic properties of zirconium- and hafnium ...

Indian Academy of Sciences (India)

2018-02-02

Feb 2, 2018 ... ties. The volume optimization curves (both LDA and GGA) for binary Rh3V, Rh3Zr and Rh3Hf compounds are shown in ... the strength of covalent bonding of the given material. ..... Bulk modulus is correlated with binding energy or cohesive energy of atoms, since it is a measure of average atomic bond.

A new position-sensitive detector for thermal and epithermal neutrons

International Nuclear Information System (INIS)

Jeavons, A.P.; Ford, N.L.; Lindberg, B.; Sachot, R.

1977-01-01

A new two-dimensional position-sensitive neutron detector is described. It is based on (n,γ) neutron resonance capture in a foil with subsequent detection of internal conversion electrons with a high-density proportional chamber. Large-area detectors with a 1 mm spatial resolution are feasible. A detection efficiency of 50% is possible for thermal neutrons using gadolinium-157 foil and for epithermal neutrons using hafnium-177. (Auth.)

Composites having an intermetallic containing matrix

International Nuclear Information System (INIS)

Nagle, D.C.; Brupbacher, J.M.; Christodoulou, L.

1990-01-01

This paper describes a composite material. It comprises: a dispersion of in-situ precipitated second phase particles selected from the group consisting of borides, carbides, nitrides, and sulfides, in an intermetallic containing matrix selected from the group consisting of the aluminides, silicides, and beryllides of nickel, copper, titanium, cobalt, iron, platinum, gold, silver, niobium, tantalum, zinc, molybdenum, hafnium, tin, tungsten, lithium, magnesium, thorium, chromium, vanadium, zirconium, and manganese

Surface layers in the 4A group metals with implanted silicon ions

International Nuclear Information System (INIS)

Kovneristyj, Yu.K.; Vavilova, V.V.; Krasnopevtsev, V.V.; Galkin, L.N.; Kudyshev, A.N.; Klechkovskaya, V.V.

1987-01-01

A study was made on the change of structure and phase composition of fine near the surface layers of 4A group metals (Hf, Zr, Ti) during ion Si implantation and successive thermal annealing at elevated temperatures. Implantation of Si + ions with 30 or 16 keV energy in Ti, Zr and Hf at room temperature results to amorphization of metal surface layer. The surface hafnium and titanium layer with implanted Si atoms due to interaction with residual atmosphere of oxygen turns during annealing at 870 K to amorphous solid solution of HfO 2m or TiO 2 with Si, preventing further metal oxidation; layers of amorphous alloy are characterized by thermal stability up to 1270 K. Oxidation of the surface amorphous layer in residual oxygen atmosphere and its crystallization in ZrO 2 take place in result of Zr annealing with implanted Si ions at temperature not exceeding 870 K. Similar phenomena are observed in the case of hafnium with implanted oxygen ions or small dose of silicon ions. Thermal stability of amorphous layers produced during ion implantation of Si in Ti, Zr and Hf corresponds to scale resistance of monolithic alloys in Ti-Si, Zr-Si and Hf-Si systems

Thermal effects on the Raman phonon of few-layer phosphorene

Energy Technology Data Exchange (ETDEWEB)

Ling, Zhi-Peng; Ang, Kah-Wee, E-mail: eleakw@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583 (Singapore); Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546 (Singapore)

2015-12-01

Two-dimensional phosphorene is a promising channel material for next generation transistor applications due to its superior carrier transport property. Here, we report the influence of thermal effects on the Raman phonon of few-layer phosphorene formed on hafnium-dioxide (HfO{sub 2}) high-k dielectric. When annealed at elevated temperatures (up to 200 °C), the phosphorene film was found to exhibit a blue shift in both the out-of-plane (A{sup 1}{sub g}) and in-plane (B{sub 2g} and A{sup 2}{sub g}) phonon modes as a result of compressive strain effect. This is attributed to the out-diffusion of hafnium (Hf) atoms from the underlying HfO{sub 2} dielectric, which compresses the phosphorene in both the zigzag and armchair directions. With a further increase in thermal energy beyond 250 °C, strain relaxation within phosphorene eventually took place. When this happens, the phosphorene was unable to retain its intrinsic crystallinity prior to annealing, as evident from the broadening of full-width at half maximum of the Raman phonon. These results provide an important insight into the impact of thermal effects on the structural integrity of phosphorene when integrated with high-k gate dielectric.

Far East Asia | Page 187 | IDRC - International Development ...

International Development Research Centre (IDRC) Digital Library (Canada)

E-commerce in Asia has been receiving considerable attention as a result of the ... social, methodological, and security issues related to this emerging business ... the state-of-practice and trends in information and communication technologies ...

36 CFR 223.187 - Determinations of unprocessed timber.

Science.gov (United States)

2010-07-01

... generally recognized by the industry as setting a selling standard; and, (ii) A statement by the... setting a selling standard. (3) Lumber, construction timbers, or cants for remanufacture, except western... or better, with a maximum cross section of 2,000 square centimeters (310 square inches) for any...

Far East Asia | Page 187 | IDRC - International Development ...

International Development Research Centre (IDRC) Digital Library (Canada)

Hyeun-Suk Rhee (Director, Asian and Pacific Training Centre for Information and Communication Technology for Development, Incheon, Republic of Korea). Read more about Digital Review of Asia Pacific 2009–2010. Language English. Les exemples présentés dans Success Stories in Asian Aquaculture illustrent la ...

187 Learning for Transformation: Empowering the Nigerian Child ...

African Journals Online (AJOL)

Abstract. The search for a libertarian education; which emphasizes learners' empowerment and ... as an alternative to the traditional teaching method; to facilitate the libertarian ... perform or succeed in our modern competitive world. Thus, the.

Page | 187 JOINT ACCOUNT CONTRACT: ISSUES, LAW AND ...

African Journals Online (AJOL)

Fr. Ikenga

the contractual relationship of a banker and the joint account operators. ... obligations of the survivor of joint account operators if the other is deceased is what is .... judicial pronouncements highlighted so far, it is evident that Purpose Theory is.

Thermophysical Properties of Matter - The TPRC Data Series. Volume 4. Specific Heat - Metallic Elements and Alloys

Science.gov (United States)

1971-01-01

Indium—Indium alloys—Iron—iron alloys— lanthanum — load—lead alloys—lithium—lithium alloya—«agnaslum—magnaalum alloys—manganas^ —naoganasa alloys—marcury...Germanium 21 Gold 22 Hafnium 23 Holmium 24 Indium 25 Iridium 26 Iron 27 Lanthanum 28 Lead 29 Lithium 30 Lutetium 31 Magnesium 32 Manganese 33...hexahydrate (ErC^-eHjO Erbium gallate (see Trierbium pentagallium 1 dodecaoxide) 4 5 65 822 Freon 10 (see Carbon tetrachloride) Freon 11

Out-of-plane strain effect on silicon-based flexible FinFETs

KAUST Repository

Ghoneim, Mohamed T.; Alfaraj, Nasir; Sevilla, Galo T.; Fahad, Hossain M.; Hussain, Muhammad Mustafa

2015-01-01

Summary form only given. We report out-of-plane strain effect on silicon based flexible FinFET, with sub 20 nm wide fins and hafnium silicate based high-κ gate dielectric. Since ultra-thin inorganic solid state substrates become flexible with reduced thickness, flexing induced strain does not enhance performance. However, detrimental effects arise as the devices are subject to various out-of-plane stresses (compressive and tensile) along the channel length.

Evaluated phase diagrams of binary metal-tellurium systems of the D-block transition elements

International Nuclear Information System (INIS)

Chattopadhyay, G.; Bharadwaj, S.R.

1989-01-01

The binary phase diagrams of metal-tellurium systems for twenty seven d-block transition elements have been critically evaluated. Complete phase diagrams are presented for the elements, chromium, manganese, iron, cobalt, nickel, copper, molybdenum, palladium, silver, lanthanum, platinum and gold, whereas, for scandium, titanium, vanadium, yttrium, zirconium, niobium, technitium, ruthenium, rhodium, hafnium, tantalum, tungsten , rhenium, osmium and iridium, the phase diagrams are incomplete and tentative. (author). 20 refs., 27 tabs., 27 figs

Out-of-plane strain effect on silicon-based flexible FinFETs

KAUST Repository

Ghoneim, Mohamed T.

2015-06-21

Summary form only given. We report out-of-plane strain effect on silicon based flexible FinFET, with sub 20 nm wide fins and hafnium silicate based high-κ gate dielectric. Since ultra-thin inorganic solid state substrates become flexible with reduced thickness, flexing induced strain does not enhance performance. However, detrimental effects arise as the devices are subject to various out-of-plane stresses (compressive and tensile) along the channel length.

Chimeric classical swine fever (CSF)-Japanese encephalitis (JE) viral particles as a non-transmissible bivalent marker vaccine candidate against CSF and JE infections

Science.gov (United States)

A trans-complemented CSF- JE chimeric viral replicon was constructed using an infectious cDNA clone of the CSF virus (CSFV) Alfort/187 strain. The E2 gene of CSFV Alfort/187 strain was deleted and the resultant plasmid pA187delE2 was inserted by a fragment containing the region coding for a truncate...

Re/Os cosmochronometer: measurement of neutron cross sections

International Nuclear Information System (INIS)

Mosconi, M.

2007-01-01

This experimental work is devoted to the improved assessment of the Re/Os cosmochronometer. The dating technique is based on the decay of 187 Re (t 1/2 =41.2 Gyr) into 187 Os and determines the age of the universe by the time of onset of nucleosynthesis. The nucleosynthesis mechanisms, which are responsible for the 187 Re/ 187 Os pair, provide the possibility to identify the radiogenic fraction of 187 Os exclusively by nuclear physics considerations. Apart from its radiogenic component, 187 Os can be synthesized otherwise only by the s process, which means that this missing fraction can be reliably determined and subtracted by proper s-process modeling. On the other hand, 187 Re is almost completely produced by the r process. The only information needed for the interpretation as a cosmic clock is the production rate of 187 Re as a function of time. The accuracy of the s-process calculations that are needed to determine the nucleosynthetic abundance of 187 Os depends on the quality of the neutron capture cross sections averaged over the thermal neutron spectrum at the s-process sites. Laboratory measurements of these cross sections have to be corrected for the effect of nuclear levels, which can be significantly populated at the high stellar temperatures during the s process. The neutron capture cross sections of 186 Os, 187 Os and 188 Os have been measured at the CERN n TOF facility in the range between 0.7 eV and 1 MeV. From these data, Maxwellian averaged cross sections have been determined for thermal energies from 5 to 100 keV with an accuracy around 4%, 3%, and 5% for 186 Os, 187 Os, and 188 Os, respectively. Since, the first excited state in 187 Os occurs at 9.75 keV, the cross section of this isotope requires a substantial correction for thermal population of low lying nuclear levels. This effect has been evaluated on the basis of resonance data derived in the (n, γ) experiments and by an improved measurements of the inelastic scattering cross section for

Photo-nuclear reactions on nuclei in the W-Re-Os region

International Nuclear Information System (INIS)

Shizuma, Toshiyuki; Hayakawa, Takehito; Goko, Shinji; Utsunomiya, Hiroaki; Ohgaki, Hideaki; Mohr, Peter; Lui, Yiu-Wing; Goriely, Stephane

2005-01-01

Photo-disintegration cross sections for 186 W, 187 Re, 188 Os have been measured at energies close to the neutron thresholds using quasi monochromatic γ-ray beams from laser Compton scattering (LCS). The data are used to evaluate the cross sections for the inverse neutron capture reactions within the Hauser-Feshbach statistical model. The influence of the radiative neutron capture on the 9.75 keV first excited state of 187 Os which is substantially populated in stellar plasmas at typical s-process temperatures is examined in connection to the 187 Re- 187 Os cosmochronology. (author)

Simultaneous Detection of Both RNA and DNA Viruses Infecting Dry Bean and Occurrence of Mixed Infections by BGYMV, BCMV and BCMNV in the Central-West Region of Mexico

Directory of Open Access Journals (Sweden)

Elizabeth Chiquito-Almanza

2017-03-01

Full Text Available A multiplex reverse transcription polymerase chain reaction (RT-PCR assay was developed to simultaneously detect bean common mosaic virus (BCMV, bean common mosaic necrotic virus (BCMNV, and bean golden yellow mosaic virus (BGYMV from common bean leaves dried with silica gel using a single total nucleic acid extraction cetyl trimethyl ammonium bromide (CTAB method. A mixture of five specific primers was used to amplify three distinct fragments corresponding to 272 bp from the AC1 gene of BGYMV as well as 469 bp and 746 bp from the CP gene of BCMV and BCMNV, respectively. The three viruses were detected in a single plant or in a bulk of five plants. The multiplex RT-PCR was successfully applied to detect these three viruses from 187 field samples collected from 23 municipalities from the states of Guanajuato, Nayarit and Jalisco, Mexico. Rates of single infections were 14/187 (7.5%, 41/187 (21.9%, and 35/187 (18.7%, for BGYMV, BCMV, and BCMNV, respectively; 29/187 (15.5% samples were co-infected with two of these viruses and 10/187 (5.3% with the three viruses. This multiplex RT-PCR assay is a simple, rapid, sensitive, and cost-effective method for detecting these viruses in the common bean and can be used for routine molecular diagnosis and epidemiological studies.

Separation of magnesium from magnesium chloride and zirconium and/or hafnium subchlorides in the production of zirconium and/or hafnium sponge metal

International Nuclear Information System (INIS)

Abodishish, H.A.M.; Adams, R.J.; Kearl, S.R.

1992-01-01

This patent describes the producing of a refractory metal wherein a sponge refractory metal is produced as an intermediate product by the use of magnesium with the incidental production of magnesium chloride, and wherein residual magnesium is separated from the magnesium chloride and from refractory metal to a vacuum distillation step which fractionally distills the magnesium, the magnesium chloride, and the metal sub-chlorides; the steps of: recovering fractionally distilled vapors of magnesium chloride and metal sub-chlorides from a sponge refractory metal; separately condensing the vapors as separately recovered; and recycling the separately recovered magnesium at a purity of at least about 96%

Re/Os cosmochronometer: measurement of neutron cross sections

Energy Technology Data Exchange (ETDEWEB)

Mosconi, M.

2007-12-21

This experimental work is devoted to the improved assessment of the Re/Os cosmochronometer. The dating technique is based on the decay of {sup 187}Re (t{sub 1/2}=41.2 Gyr) into {sup 187}Os and determines the age of the universe by the time of onset of nucleosynthesis. The nucleosynthesis mechanisms, which are responsible for the {sup 187}Re/{sup 187}Os pair, provide the possibility to identify the radiogenic fraction of {sup 187}Os exclusively by nuclear physics considerations. Apart from its radiogenic component, {sup 187}Os can be synthesized otherwise only by the s process, which means that this missing fraction can be reliably determined and subtracted by proper s-process modeling. On the other hand, {sup 187}Re is almost completely produced by the r process. The only information needed for the interpretation as a cosmic clock is the production rate of {sup 187}Re as a function of time. The accuracy of the s-process calculations that are needed to determine the nucleosynthetic abundance of {sup 187}Os depends on the quality of the neutron capture cross sections averaged over the thermal neutron spectrum at the s-process sites. Laboratory measurements of these cross sections have to be corrected for the effect of nuclear levels, which can be significantly populated at the high stellar temperatures during the s process. The neutron capture cross sections of {sup 186}Os, {sup 187}Os and {sup 188}Os have been measured at the CERN n TOF facility in the range between 0.7 eV and 1 MeV. From these data, Maxwellian averaged cross sections have been determined for thermal energies from 5 to 100 keV with an accuracy around 4%, 3%, and 5% for {sup 186}Os, {sup 187}Os, and {sup 188}Os, respectively. Since, the first excited state in {sup 187}Os occurs at 9.75 keV, the cross section of this isotope requires a substantial correction for thermal population of low lying nuclear levels. This effect has been evaluated on the basis of resonance data derived in the (n, {gamma

Production and analysis of some atomic emission spectra in the vacuum ultraviolet

International Nuclear Information System (INIS)

Meijer, F.G.

1979-01-01

The development of technical facilities for spectra analysis are described including the design, construction and adjustment of a grazing incidence spectrograph for the extreme ultraviolet and the improvements in light sources. The investigations of the fifth and fourth spectra of tantalum, the analysis of the sixth spectrum of tungsten, the extension of the analysis of the fourth spectrum of hafnium and a start of the analysis of the seventh spectrum of rhenium are presented. (C.F.)

Environmental, social, and corporate report 2010 - Cezus Ugine (Areva)

International Nuclear Information System (INIS)

2011-01-01

CEZUS, a subsidiary of AREVA, is the global leader in the market for zirconium, the metal used, among other things, for nuclear fuel cladding. CEZUS's operations are distributed over six sites. The site in Ugine handles production of ingots and transformation of zirconium, titanium, tantalum, and hafnium into semi-finished products. This document shows details of the CEZUS Ugine facility and its 2010 initiatives on: consumption and waste management, risk management, environmental and safety management, social and corporate responsibilities

Annual reports in inorganic and general syntheses 1974

CERN Document Server

Niedenzu, Kurt

1975-01-01

Annual Reports in Inorganic and General Syntheses-1974 presents an organized annual summary of synthetic developments in inorganic chemistry and its related areas. The book discusses the chemistry of simple and complex metal hydrides of main groups I, II, and III, boron, aluminium, gallium, indium, thallium, silicon, germanium, tin, lead, phosphorus, arsenic, antimony, bismuth, chalcogens, halogens, and pseudohalogens. The text also describes the chemistry of scandium, yttrium, lanthanides, actinides, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, ma

Environmental, social, and corporate report 2012 - Cezus Ugine (Areva)

International Nuclear Information System (INIS)

2013-01-01

CEZUS, a subsidiary of AREVA, is the global leader in the market for zirconium, the metal used, among other things, for nuclear fuel cladding. CEZUS's operations are distributed over six sites. The site in Ugine handles production of ingots and transformation of zirconium, titanium, tantalum, and hafnium into semi-finished products. This document shows details of the CEZUS Ugine facility and its 2012 initiatives on: consumption and waste management, risk management, environmental and safety management, social and corporate responsibilities

Proceedings of IEEE International Conference on Nanotechnology (4th) held at the Technische Universitat Muenchen, Munich, Germany on 17-19 Aug 2004.

Science.gov (United States)

2004-08-01

Based Membranes: A Platform for Studying Nanofluidics , J.K. Holt, H.G. Park, A. Noy, T. Huser, D. Eaglesham, and O. Bakajin, (Chemistry and Materials...56122 Pisa, Italy, 2IEIIT-CNR, Pisa, Italy) TH2_3_4 How Quantum Effects and Unintentional Doping Affect the Threshold Voltage of Narrow-Width SOI...Hafnium Doped Tantalum Oxide High k Film, J. Lu and Y. Kuo, (The Thin Film Nano and Microelectronics Research Laboratory, Texas A&M University, College

Spectroscopies et modélisation de verres de silice dopés d'ions de terre rare - influence du co-dopage

OpenAIRE

Alombert-Goget , Guillaume

2007-01-01

This study concerns the role of a co-doping agent on the environment of the rare earth ions in silica glass and its consequences on the spectroscopy of the luminescent element. Two different co-doping agents were studied: aluminium and hafnium ions. The samples of doped and co-doped glasses were obtained by sol-gel process and were studied by different experimental methods: luminescence spectroscopy, FLN spectroscopy, Raman spectroscopy, and EXAFS spectroscopy. In parallel some numerical simu...

Annual reports in inorganic and general syntheses 1972

CERN Document Server

Niedenzu, Kurt

1973-01-01

Annual Reports in Inorganic and General Syntheses-1972 presents an organized annual summary of synthetic developments in inorganic chemistry and its related areas. The book discusses alkali and alkaline earth elements, alloys, silver, gold, zinc, cadmium, mercury, boron, aluminum, gallium, indium, thallium, yttrium, scandium, lanthanides, actinides, titanium, zirconium, hafnium, Group V and VI transition elements, manganese, technetium, rhenium, iron, cobalt, nickel, ruthenium, osmium, rhodium, and iridium. The text also describes the chemistry of palladium, platinum, silicon, germanium, tin,

New K-edge-balanced contrast phantom for image quality assurance in projection radiography

Science.gov (United States)

Cresens, Marc; Schaetzing, Ralph

2003-06-01

X-ray-absorber step-wedge phantoms serve in projection radiography to assess a detection system's overall exposure-related signal-to-noise ratio performance and contrast response. Data derived from a phantom image, created by exposing a step-wedge onto the image receptor, are compared with predefined acceptance criteria during periodic image quality assurance (QA). For contrast-related measurements, in particular, the x-ray tube potential requires accurate setting and low ripple, since small deviations from the specified kVp, causing energy spectrum changes, lead to significant image signal variation at high contrast ratios. A K-edge-balanced, rare-earth-metal contrast phantom can generate signals that are significantly more robust to the spectral variability and instability of exposure equipment in the field. The image signals from a hafnium wedge, for example, are up to eight times less sensitive to spectral fluctuations than those of today"s copper phantoms for a 200:1 signal ratio. At 120 kVp (RQA 9), the hafnium phantom still preserves 70% of the subject contrast present at 75 kVp (RQA 5). A copper wedge preserves only 7% of its contrast over the same spectral range. Spectral simulations and measurements on prototype systems, as well as potential uses of this new class of phantoms (e.g., QA, single-shot exposure response characterization) are described.

Oxidation and Volatilization from Tantalum Alloy T-222 During Air Exposure

Energy Technology Data Exchange (ETDEWEB)

Smolik, Galen Richard; Petti, David Andrew; Sharpe, John Phillip; Schuetz, Stanley Thomas

2000-10-01

Tantalum alloys are one of the refractory metals with renewed consideration for high temperatures in fusion reactor applications. Tantalum alloys perform well in protective environments but oxidized readily in gases containing higher oxygen levels. In addition, the radioactive isotope Ta-182 would be produced in tantalum and could be a significant contributor to dose if mobilized. Other isotopes of importance are produced from tungsten and hafnium. Mobilization of activated products during an accident with air ingress is therefore a safety issue. In this study, we measured the extent of oxidation and mobilization from tantalum alloy T-222 oxidized in flowing air between 500 and 1200°C. This alloy nominally contains 10 wt% tungsten, 2.5 wt% hafnium and 0.01 wt% carbon. We found that the mobilization of Ta and Hf was closely linked to the occurrence of oxide spalling. These elements showed no migration from the test chamber. Some W was mobilized by volatilization as evidenced by transport from the chamber. Tungsten volatilization could occur primarily during initial stages of oxidation before an oxide scale forms and impedes the process. The mobilization of Ta and W are presented in terms of the mass flux (g/m 2 -h) as a function of test temperature. These measurements along with specific designs, activation calculations, and accident scenarios provide information useful for dose calculations of future fusion devices

Oxidation and Volatilization from Tantalum Alloy T-222 During Air Exposure

Energy Technology Data Exchange (ETDEWEB)

Smolik, G.R.; Petti, D.A.; Sharpe, J.P.; Schuetz, S.T.

2000-10-31

Tantalum alloys are one of the refractory metals with renewed consideration for high temperatures in fusion reactor applications. Tantalum alloys perform well in protective environments but oxidized readily in gases containing higher oxygen levels. In addition, the radioactive isotope Ta-182 would be produced in tantalum and could be a significant contributor to dose if mobilized. Other isotopes of importance are produced from tungsten and hafnium. Mobilization of activated products during an accident with air ingress is therefore a safety issue. In this study, we measured the extent of oxidation and mobilization from tantalum alloy T-222 oxidized in flowing air between 500 and 1200 C. This alloy nominally contains 10 wt% tungsten, 2.5 wt% hafnium and 0.01 wt% carbon. We found that the mobilization of Ta and Hf was closely linked to the occurrence of oxide spalling. These elements showed no migration from the test chamber. Some W was mobilized by volatilization as evidenced by transport from the chamber. Tungsten volatilization could occur primarily during initial stages of oxidation before an oxide scale forms and impedes the process. The mobilization of Ta and W are presented in terms of the mass flux (g/m 2 -h) as a function of test temperature. These measurements along with specific designs, activation calculations, and accident scenarios provide information useful for dose calculations of future fusion devices.

(V,Nb)-doped half Heusler alloys based on {Ti,Zr,Hf}NiSn with high ZT

International Nuclear Information System (INIS)

Rogl, G.; Sauerschnig, P.; Rykavets, Z.; Romaka, V.V.; Heinrich, P.; Hinterleitner, B.; Grytsiv, A.; Bauer, E.; Rogl, P.

2017-01-01

Half Heusler alloys are among the most promising materials for thermoelectric generators as they can be used in a wide temperature range and their starting materials are abundant and cheap, the latter as long as no hafnium is involved. For Sb-doped Ti 0.5 Zr 0.25 Hf 0.25 NiSn Sakurada and Shutoh in 2008 have published ZT max  = 1.5 at 690 K, a value that hitherto was never reproduced independently. In this paper we successfully prepared Ti 0.5 Zr 0.25 Hf 0.25 NiSn with ZT max  = 1.5, however, at higher temperature (825 K). As the main goal is to produce hafnium – free half Heusler alloys, we investigated the influence of niobium or vanadium dopants on Ti x Zr 1−x NiSn 0.98 Sb 0.02 , reaching ZTs > 1.2 and thermal-electric conversion efficiencies up to 13.1%. For Hf-free n-type TiNiSn-based half Heusler alloys these values are unsurpassed. In order to further improve our thermoelectric materials our study is completed by electrical resistivity and thermal conductivity data in the low temperature range but also by mechanical properties (elastic moduli, hardness) at room temperature. The electrical properties have been discussed in comparison with DFT calculations.

Oxidation kinetics of some zirconium alloys in flowing carbon dioxide at high temperatures

International Nuclear Information System (INIS)

Kohli, R.

1980-01-01

The oxidation kinetics of three zirconium alloys (Zr-2.2 wt% Hf, Zr-2.5 wt% Nb, and Zr-3 wt% Nb-1 wt% Sn) have been measured in flowing carbon dioxide in the temperature range from 873 to 1173 K to 120 ks (2000 min). At all oxidation temperatures, Zr-2.5 Nb and Zr-3 Nb-1 Sn showed a transition to rapid linear kinetics after initial parabolic oxidation. The Zr-2.2 Hf showed this transition at temperatures in the range from 973 to 1173 K; at 873 K, no transition was observed within the oxidation times reported. The Zr-2.2 Hf showed the smallest weight gains, followed in order by Zr-2.5 Nb and Zr-3 Nb-1 Sn. Increased oxidation rates and shorter times-to-rate-transition of Zr-2.2 Nb and Zr-1 Sn as compared with Zr-2.2 Hf can be attributed to the presence of niobium, tin, and hafnium in the alloys. This is considered in terms of the Nomura-Akutsu model, according to which hafnium should delay the rate transition, while niobium and tin lead to shorter times-to-rate-transition. The scale on Zr-2.2 Hf was identified as monoclinic zirconia, while the tetragonal phase, 6ZrO 2 .Nb 2 O 5 , was contained in the monoclinic zirconia scales on both other alloys

Electrical properties of radio-frequency sputtered HfO{sub 2} thin films for advanced CMOS technology

Energy Technology Data Exchange (ETDEWEB)

Sarkar, Pranab Kumar; Roy, Asim, E-mail: 28.asim@gmail.com [Department of Physics, National Institute of Technology Silchar, Silchar-788010, Assam, India Phone: +91-3842-224879 (India)

2015-08-28

The Hafnium oxide (HfO{sub 2}) high-k thin films have been deposited by radio frequency (rf) sputtering technique on p-type Si (100) substrate. The thickness, composition and phases of films in relation to annealing temperatures have been investigated by using cross sectional FE-SEM (Field Emission Scanning Electron Microscope) and grazing incidence x-ray diffraction (GI-XRD), respectively. GI-XRD analysis revealed that at annealing temperatures of 350°C, films phases change to crystalline from amorphous. The capacitance-voltage (C-V) and current-voltage (I-V) characteristics of the annealed HfO{sub 2} film have been studied employing Al/HfO{sub 2}/p-Si metal–oxide–semiconductor (MOS) structures. The electrical properties such as dielectric constant, interface trap density and leakage current density have been also extracted from C-V and I-V Measurements. The value of dielectric constant, interface trap density and leakage current density of annealed HfO{sub 2} film is obtained as 23,7.57×1011eV{sup −1} cm{sup −2} and 2.7×10{sup −5} Acm{sup −2}, respectively. In this work we also reported the influence of post deposition annealing onto the trapping properties of hafnium oxide and optimized conditions under which no charge trapping is observed into the dielectric stack.

Three dimensional graphene transistor for ultra-sensitive pH sensing directly in biological media.

Science.gov (United States)

Ameri, Shideh Kabiri; Singh, Pramod K; Sonkusale, Sameer R

2016-08-31

In this work, pH sensing directly in biological media using three dimensional liquid gated graphene transistors is presented. The sensor is made of suspended network of graphene coated all around with thin layer of hafnium oxide (HfO2), showing high sensitivity and sensing beyond the Debye-screening limit. The performance of the pH sensor is validated by measuring the pH of isotonic buffered, Dulbecco's phosphate buffered saline (DPBS) solution, and of blood serum derived from Sprague-Dawley rat. The pH sensor shows high sensitivity of 71 ± 7 mV/pH even in high ionic strength media with molarities as high as 289 ± 1 mM. High sensitivity of this device is owing to suspension of three dimensional graphene in electrolyte which provides all around liquid gating of graphene, leading to higher electrostatic coupling efficiency of electrolyte to the channel and higher gating control of transistor channel by ions in the electrolyte. Coating graphene with hafnium oxide film (HfO2) provides binding sites for hydrogen ions, which results in higher sensitivity and sensing beyond the Debye-screening limit. The 3D graphene transistor offers the possibility of real-time pH measurement in biological media without the need for desaltation or sample preparation. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of pH on the optical and structural properties of HfO{sub 2}:Ln{sup 3+}, synthesized by hydrothermal route

Energy Technology Data Exchange (ETDEWEB)

Montes, E., E-mail: emontesr@live.com.mx [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada IPN, Legaría 694, 11500, D.F. (Mexico); Martínez-Merlín, I.; Guzmán-Olguín, J.C.; Guzmán-Mendoza, J. [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada IPN, Legaría 694, 11500, D.F. (Mexico); Martín, I.R. [Depto. de Física Fundamental y Experimental, Electrónica y Sistemas, Univ. de La Laguna, Av. Astrofísico Francisco Sánchez s/n E-38206, La Laguna. Tenerife (Spain); García-Hipólito, M. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito Exterior, Cd. Universitaria, 04510, D.F. (Mexico); Falcony, C. [Departamento de Física, CINVESTAV IPN, Apartado Postal 14-740, 07000, D.F. (Mexico)

2016-07-15

In this work, the influence of the chlorine ions in the optical and structural properties of hafnium oxide (HfO{sub 2}) doped with europium (Eu{sup 3+}) and terbium (Tb{sup 3+}) are reported. The synthesis was conducted by hydrothermal route at a temperature of 200 °C, with a reaction time of 80 min and a concentration of 3 mol% of both dopants, in relation to hafnium in solution. In order to study the influence of acidity on the kinetics of reaction, the pH of the precursor solution was varied in the range of pH=4 to pH=12. X-ray powder diffraction patterns showed that the materials crystallized better under alkaline conditions with pH=11, noting a better crystallinity in the material doped with Eu{sup 3+}showed a better crystallinity that Tb{sup 3+} ions. The characteristic rhombohedral microstructure of HfO{sub 2} in the monoclinic phase was observed in alkaline media. Photoluminescent spectra showed the characteristic peaks of the emissions for both Eu an Tb dopants, where the intensity of the luminescent emission increases by decreasing the concentration of chlorine ions. On the other hand, it was found that radiative life kinetics of the dopant is related to the kinetics of crystallization, and therefore, to the acidity of the precursor solution.

Production of long-lived hafnium isomers in reactor irradiations

Czech Academy of Sciences Publication Activity Database

Adam, Jindřich

-, - (2006), s. 48-56 ISSN 1574-1818 R&D Projects: GA MŠk 1P04LA213 Institutional research plan: CEZ:AV0Z10480505 Keywords : production * Hf Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders

Iron(3) chloride interaction with zirconium and hafnium tetrahalides

International Nuclear Information System (INIS)

Berdonosov, S.; Kharisov, B.I.; Melikhov, I.V.

1988-01-01

Using FeCl 3 , labelled with 36 Cl radionuclide, it is shown, that during reaction between FeCl 3 and MCl (M=Zr, Hf) resulting in Cl 2 splitting-off and FeMCl 6 formation, chlorine is splitted from MCl 4 . From the analysis of Moessbauer spectra and visual observations it follows, that reaction between FeCl 3 and MBr 4 starts at 50 deg C temperature, whereupon bromine and FeMCl 3 Br 3 compounds are formed. Considerations about the possible mechanism of reactions between FeCl 3 and MCl 4 or MBr 4 are proposed

Spectroscopy of very neutron-deficient hafnium and tungsten isotopes

Energy Technology Data Exchange (ETDEWEB)

Dracoulis, G D; Fabricius, B; Davidson, P M [Australian National Univ., Canberra, ACT (Australia). Dept. of Nuclear Physics; Macchiavelli, A O; Oliviera, J; Burde, J; Stephens, F; Deleplanque, M A [Lawrence Berkeley Lab., CA (United States)

1992-08-01

Level schemes of the very neutron-deficient isotopes {sup 158}Hf and {sup 162}W have been identified, and that for {sup 164}W extended. Alignment of the H{sub 9/2} neutrons is suggested. (author). 12 refs., 7 figs.

Nuclear-chemistry research and spectroscopy with radioactive sources. Eighteenth annual progress report

International Nuclear Information System (INIS)

Fink, R.W.

1982-01-01

Progress is reported on nuclear spectroscopy studies including lifetimes of the g/sub 7/2/ shell-model intruder states in 107 109 Ag, lifetime of the new /sup 187m/Au isomer, the decay of 187 Au - 187 Pt, decay of /sup 201m,g/Po, 203 At, and 125 Ba, and L-shell orbital EC probability and decay energy in 207 Bi decay. Also progress on nuclear model calculations of nuclear structure is reported

Purification in the interaction between yttria mould and Nb-silicide-based alloy during directional solidification: A novel effect of yttrium

International Nuclear Information System (INIS)

Ma, Limin; Tang, Xiaoxia; Wang, Bin; Jia, Lina; Yuan, Sainan; Zhang, Hu

2012-01-01

Nb-silicide-based alloys were directionally solidified in yttria moulds. As a result of thermal dissociation of yttria, the alloys were slightly contaminated with oxygen, which caused a competitive oxidation between yttrium and hafnium. The addition of 0.15 at.% yttrium reduced the oxygen increment by 42%, because the buoyant inclusions concentrated around the top surface. The yttrium addition caused a significant purification of the interaction between the yttria mould and the Nb-silicide-based alloys during the directional solidification.

Zirconium sponge and other forms of virgin metal for nuclear applications - approved standard 1973

International Nuclear Information System (INIS)

Anon.

1975-01-01

This specification covers virgin zirconium metal commonly designated as sponge because of its porous, sponge-like texture, but it may also take other forms such as chunklets. One grade is described which is designated as reactor grade R-1, suitable for use in nuclear applications. The most important characteristic of the reactor grade is its low nuclear cross section as achieved by removal of hafnium and careful quality control in manufacturing procedures to prevent contamination with other high cross section materials

Annual report of the Metallurgy Division - period ending December 1975

International Nuclear Information System (INIS)

1976-01-01

The R and D activities of the Metallurgy Division of the Bhabha Atomic Research Centre, Bombay (India) during 1975 are described. Some of the R and D programmes of particular interest to nuclear technology are: (1) flowsheet development for the production of rare metals and alloys of nuclear use e.g. hafnium, beryllium, zirconium (2) metallurgical, irradiation hardening and corrosion studies on Zr and Zr-base alloys and (3) studies of nuclear ceramic materials such as UO2 and beryllia. (M.G.B.)

Temperature Effects on a-IGZO Thin Film Transistors Using HfO2 Gate Dielectric Material

OpenAIRE

Lin, Yu-Hsien; Chou, Jay-Chi

2014-01-01

This study investigated the temperature effect on amorphous indium gallium zinc oxide (a-IGZO) thin film transistors (TFTs) using hafnium oxide (HfO2) gate dielectric material. HfO2 is an attractive candidate as a high-κ dielectric material for gate oxide because it has great potential to exhibit superior electrical properties with a high drive current. In the process of integrating the gate dielectric and IGZO thin film, postannealing treatment is an essential process for completing the chem...

Osmium isotopic tracing of atmospheric emissions from an aluminum smelter

Science.gov (United States)

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.

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