Structural, thermodynamic, and electronic properties of Laves-phase NbMn2 from first principles, x-ray diffraction, and calorimetric experiments

NASA Astrophysics Data System (ADS)

Yan, X.; Chen, Xing-Qiu; Michor, H.; Wolf, W.; Witusiewicz, V. T.; Bauer, E.; Podloucky, R.; Rogl, P.

2018-03-01

By combining theoretical density functional theory (DFT) and experimental studies, structural and magnetic phase stabilities and electronic structural, elastic, and vibrational properties of the Laves-phase compound NbMn2 have been investigated for the C14, C15, and C36 crystal structures. At low temperatures C14 is the ground-state structure, with ferromagnetic and antiferromagnetic orderings being degenerate in energy. The degenerate spin configurations result in a rather large electronic density of states at Fermi energy for all magnetic cases, even for the spin-polarized DFT calculations. Based on the DFT-derived phonon dispersions and densities of states, temperature-dependent free energies were derived for the ferromagnetic and antiferromagnetic C14 phase, demonstrating that the spin-configuration degeneracy possibly exists up to finite temperatures. The heat of formation Δ298H0=-45.05 ±3.64 kJ (molf .u .NbMn2) -1 was extracted from drop isoperibolic calorimetry in a Ni bath. The DFT-derived enthalpy of formation of NbMn2 is in good agreement with the calorimetric measurements. Second-order elastic constants for NbMn2 as well as for related compounds were calculated.

Laves phase UTi2 stabilized by hydrogen and its magnetic properties

NASA Astrophysics Data System (ADS)

Buturlim, V.; Havela, L.; Sowa, S.; Kim-Ngan, N.-. T. H.; Paukov, M.; Drozdenko, D.; Dopita, M.; Minarik, P.; Mašková, S.

2018-05-01

We describe basic magnetic properties of uranium-based hydrides UTi2Hx, reported in literature as a cubic Laves phase, although the UTi2 binary phase does not exist. Using a high-temperature hydrogenation, we successfully synthesized two types of such hydrides, presumably with different H concentrations, one with a smaller lattice parameter a = 850.3 pm, which is a paramagnet close to the verge of magnetic ordering, the other with a = 858.8 pm, with a ferromagnetic ground state and ordering temperature TC = 54 K.

On the magnetism of the C14 Nb0.975Fe2.025 Laves phase compound: Determination of the H-T phase diagram

NASA Astrophysics Data System (ADS)

Bałanda, Maria; Dubiel, Stanisław M.

2018-05-01

A C14 Nb0.975Fe2.025 Laves phase compound was investigated aimed at determining the H-T magnetic phase diagram. Magnetization, M, and AC magnetic susceptibility measurement were performed. Concerning the former field-cooled and zero-field-cooled M-curves were recorded in the temperature range of 2-200 K and in applied magnetic field, H, up to 1000 Oe, isothermal M(H) curves at 2 K, 5 K, 50 K, 80 K and 110 K as well as hysteresis loops at several temperatures over the field range of ±10 kOe were measured. Regarding the AC susceptibility, χ, both real and imaginary components were registered as a function of increasing temperature in the interval of 2 K-150 K at the frequencies of the oscillating field, f, from 3 Hz up to 999 Hz. An influence of the external DC magnetic field on the temperature dependence of χ was investigated, too. The measurements clearly demonstrated that the magnetism of the studied sample is weak, itinerant and has a reentrant character. Based on the obtained results a magnetic phase diagram has been constructed in the H-T coordinates.

Data on a Laves phase intermetallic matrix composite in situ toughened by ductile precipitates.

PubMed

Knowles, Alexander J; Bhowmik, Ayan; Purkayastha, Surajit; Jones, Nicholas G; Giuliani, Finn; Clegg, William J; Dye, David; Stone, Howard J

2017-10-01

The data presented in this article are related to the research article entitled "Laves phase intermetallic matrix composite in situ toughened by ductile precipitates" (Knowles et al.) [1]. The composite comprised a Fe 2 (Mo, Ti) matrix with bcc (Mo, Ti) precipitated laths produced in situ by an aging heat treatment, which was shown to confer a toughening effect (Knowles et al.) [1]. Here, details are given on a focused ion beam (FIB) slice and view experiment performed on the composite so as to determine that the 3D morphology of the bcc (Mo, Ti) precipitates were laths rather than needles. Scanning transmission electron microscopy (S(TEM)) micrographs of the microstructure as well as energy dispersive X-ray spectroscopy (EDX) maps are presented that identify the elemental partitioning between the C14 Laves matrix and the bcc laths, with Mo rejected from the matrix into laths. A TEM selected area diffraction pattern (SADP) and key is provided that was used to validate the orientation relation between the matrix and laths identified in (Knowles et al.) [1] along with details of the transformation matrix determined.

Sintered rare earth-iron Laves phase magnetostrictive alloy product and preparation thereof

DOEpatents

Malekzadeh, Manoochehr; Pickus, Milton R.

1979-01-01

A sintered rare earth-iron Laves phase magnetostrictive alloy product characterized by a grain oriented morphology. The grain oriented morphology is obtained by magnetically aligning powder particles of the magnetostrictive alloy prior to sintering. Specifically disclosed are grain oriented sintered compacts of Tb.sub.x Dy.sub.1-x Fe.sub.2 and their method of preparation. The present sintered products have enhanced magnetostrictive properties.

Ti12.5Zr21V10Cr8.5MnxCo1.5Ni46.5-x AB2-type metal hydride alloys for electrochemical storage application: Part 1. Structural characteristics

NASA Astrophysics Data System (ADS)

Bendersky, L. A.; Wang, K.; Levin, I.; Newbury, D.; Young, K.; Chao, B.; Creuziger, A.

2012-11-01

The microstructures of a series of AB2-based metal hydride alloys (Ti12.5Zr21V10Cr8.5MnxCo1.5Ni46.5-x) designed to have different fractions of non-Laves secondary phases were studied by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectrometry, and electron backscatter diffraction. The results indicate that the alloys contain a majority of hydrogen storage Laves phases and a minority of fine-structured non-Laves phases. Formation of the phases is accomplished by dendritic growth of a hexagonal C14 Laves phase. The C14 phase is followed by either a peritectic solidification of a cubic C15 Laves phase (low Mn containing alloys) or a C14 phase of different composition (high Mn containing alloys), and finally a B2 phase formed in the interdendritic regions (IDR). The interdendritic regions may then undergo further solid-state transformation into Zr7Ni10-type, Zr9Ni11-type and TiNi-type phases. As the Mn content in the alloy increases, the fraction of the C14 phase increases, whereas the fraction of C15 decreases. In the IDRs when the alloy's Mn content increases the Zr9Ni11 phases and Zr7Ni10 phase fraction first increases and then decreases, while the TiNi-based phase fraction first increases and then stabilized at 0.02. IDR compositions can be generally expressed as (Ti,Zr,V,Cr,Mn,Co)50Ni50, which accounted for 7-10% of the overall alloy volume fraction.

Manipulating the stability of crystallographic and magnetic sub-lattices: A first-order magnetoelastic transformation in transition metal based Laves phase

DOE PAGES

Yibole, H.; Pathak, A. K.; Mudryk, Y.; ...

2018-05-24

A first-order magnetoelastic transition (FOMT) is found near the triple point between ferromagnetic, antiferromagnetic and paramagnetic phases in the magneto-chemical phase diagram of (Hf1-xNbx)Fe2 Laves phase system. We show that bringing different magnetic states to the edge of stability, both as a function of the chemical composition and under the influence of external stimuli, such as temperature, pressure and magnetic field, is essential to obtain and control FOMTs. Temperature dependent X-ray diffraction experiments reveal a discontinuity in the lattice parameter a and the unit cell volume without the change in the crystal symmetry at the FOMT. Under applied pressure, themore » transition temperature drastically shifts downward at a remarkable rate of –122 K/GPa. It is this first-order magnetic transition that leads to a negative thermal expansion (NTE) with average ΔV/(VΔT) ≈ –15 × 10 –6 K –1 observed over a 90 K broad temperature range, which is uncommon for magnetoelastic NTE materials. Density functional theory calculations and microstructural analyses demonstrate that the unusual broadness of the FOMT originates from phase separation between ferro- and antiferromagnetic phases, which in turn is rooted in partial segregation of Hf and Nb and a peculiar microstructure. In conclusion, this new understanding of the composition-structure-property relationships in transition metal based Laves phases is an essential step toward a better control and more precise tailoring of rich functionalities in this group of material.« less

Manipulating the stability of crystallographic and magnetic sub-lattices: A first-order magnetoelastic transformation in transition metal based Laves phase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yibole, H.; Pathak, A. K.; Mudryk, Y.

A first-order magnetoelastic transition (FOMT) is found near the triple point between ferromagnetic, antiferromagnetic and paramagnetic phases in the magneto-chemical phase diagram of (Hf1-xNbx)Fe2 Laves phase system. We show that bringing different magnetic states to the edge of stability, both as a function of the chemical composition and under the influence of external stimuli, such as temperature, pressure and magnetic field, is essential to obtain and control FOMTs. Temperature dependent X-ray diffraction experiments reveal a discontinuity in the lattice parameter a and the unit cell volume without the change in the crystal symmetry at the FOMT. Under applied pressure, themore » transition temperature drastically shifts downward at a remarkable rate of –122 K/GPa. It is this first-order magnetic transition that leads to a negative thermal expansion (NTE) with average ΔV/(VΔT) ≈ –15 × 10 –6 K –1 observed over a 90 K broad temperature range, which is uncommon for magnetoelastic NTE materials. Density functional theory calculations and microstructural analyses demonstrate that the unusual broadness of the FOMT originates from phase separation between ferro- and antiferromagnetic phases, which in turn is rooted in partial segregation of Hf and Nb and a peculiar microstructure. In conclusion, this new understanding of the composition-structure-property relationships in transition metal based Laves phases is an essential step toward a better control and more precise tailoring of rich functionalities in this group of material.« less

Microstructure and hydrogenation properties of a melt-spun non-stoichiometric Zr-based Laves phase alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Tiebang, E-mail: tiebangzhang@nwpu.edu.cn; Zhang, Yunlong; Li, Jinshan

2016-01-15

Alloy with composition of Zr{sub 0.9}Ti{sub 0.1}V{sub 1.7} off normal stoichiometric proportion is selected to investigate the effect of defects introduced by non-stoichiometry on hydrogenation kinetics of Zr–Ti–V Laves phase alloys. Microstructure and phase constituent of melt-spun ribbons have been investigated in this work. The activation process, hydrogenation kinetics, thermodynamics characteristics and hydride phase constituent of as-cast alloy and melt-spun ribbons are also compared. Comparing with the as-cast alloy, the dominant Laves phase ZrV{sub 2} is preserved, V-BCC phase is reduced and α-Zr phase is replaced by a small amount of Zr{sub 3}V{sub 3}O phase in melt-spun ribbons. Melt-spun ribbonsmore » exhibit easy activation and fast initial hydrogen absorption on account of the increased specific surface area. However, the decrease in unit cell volume of the dominant phase leads to the decrease in hydrogen absorption capacity. Melt-spinning technique raises the equilibrium pressure and decreases the stability of hydride due to the decrease of unit cell volume and the elimination of α-Zr phase, respectively. Melt-spun ribbons with fine grains show improved hydrogen absorption kinetics comparing with that of the as-cast alloy. Meanwhile, the prevalent micro twins observed within melt-spun ribbons are believed to account for the improved hydrogen absorption kinetics. - Highlights: • Role of defects on hydrogenation kinetics of Zr-based alloys is proposed. • Microstructure and hydrogenation properties of as-cast/melt-spun alloy are compared. • Melt-spinning technique improves the hydrogenation kinetics of Zr{sub 0.9}Ti{sub 0.1}V{sub 1.7} alloy. • Refined grains and twin defects account for improved hydrogen absorption kinetics.« less

PSEUDO-BINARY SYSTEMS INVOLVING RARE EARTH LAVES PHASES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wernick, J.H.; Haszko, S.E.; Dorsi, D.

1962-06-01

The phase relations in a number of pseudo-binary systems involving rare earth Laves phases were determined. Complete series of cubic solid-solutions occur in the DyMn/sub 2/HoMn/sub 2/, HoMn/sub 2/-HoFe/sub 2/, DyMn/sub 2/-DyFe/ sub 2/, HoMn/sub 2/-HoAl/ sub 2/, TbMn/sub 2/TbAl/sub 2/, and DyMn/sub 2/-DyAl/ sub 2/ pseudobinary systems. Deviations from linearity in the lattice constants with composition occur in all these systems. Complete series of cubic solidsolutions also exist in the GdAl/sub 2/-ErAl/sub 2/, GdAl/sub 2/-PrAl/sub 2/ , GdAl/sub 2/-NdAl/sub 2/, GdAl/sub 2/-DyAl/sub 2/, TbAl/sub 2/-NdAl/sub 2/, and T bAl/sub 2/-DyAl/sub 2/ systems. For these systems, no deviation from linearitymore » occurs in the lattice constants. For the DyFe/sub 2/-DyAl/sub 2/ and DyCo/sub 2/- DyAl/sub 2/ systems, two new ternary phases, DyFeAl and DyCoAl, form and have the MgZn/sub 2/ structure. Their structures were determined from x-ray powder data only. The electronic state giving rise to the formation of these ternary phases is discussed qualitatively. For the DyMn/sub 2/TmMn/sub 2/ system, the range of composition in which the cubic MgCu/sub 2/ and hexagonal MgZn/sub 2/ structures exist are reported. No complete series of solid solutions or intermediate phases are formed in the DyNi/sub 2/-DyAl/sub 2/ system. (auth)« less

Electronic properties of Laves phase ZrFe{sub 2} using Compton spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhatt, Samir, E-mail: sameerbhatto11@gmail.com; Kumar, Kishor; Ahuja, B. L.

First-ever experimental Compton profile of Laves phase ZrFe{sub 2}, using indigenous 20 Ci {sup 137}Cs Compton spectrometer, is presented. To analyze the experimental electron momentum density, we have deduced the theoretical Compton profiles using density functional theory (DFT) and hybridization of DFT and Hartree-Fock scheme within linear combination of atomic orbitals (LCAO) method. The energy bands and density of states are also calculated using LCAO prescription. The theoretical profile based on local density approximation gives a better agreement with the experimental profile than other reported schemes. The present investigations validate the inclusion of correlation potential of Perdew-Zunger in predicting themore » electronic properties of ZrFe{sub 2}.« less

The hardness, microstructure, and pitting resistance of austenitic stainless steel Fe25Ni15Cr with the addition of tungsten, niobium, and vanadium

NASA Astrophysics Data System (ADS)

Prifiharni, Siska; Anwar, Moch. Syaiful; Nikitasari, Arini; Mabruri, Efendi

2018-05-01

In this work, the effect of 2% W, 1%Nb, and 1% V addition on the hardness, microstructure, and pitting resistance to austenitic stainless steel Fe25Ni15Cr was investigated. The specimens were prepared in induction melting furnace, followed by homogenizing at 1100°C for 24 h. Then, the specimens were solution treated at 975°C for 2 h followed by water quenching and aging at 725°C for 15 h. The hardness was measured by using Rockwell hardness B, and metallographic observation was conducted using optical microscope and SEM-EDS. The results show that the increament of W, Nb, and V in the austenitic stainless steel Fe25Ni15Crby increased the hardness. The metal carbide precipitation occurred at grain boundaries in niobium free alloy. The addition of Nb in the alloy promotes the Laves phase transformation, and addition of V increase Nb content in the Laves phase. Laves phase formation in alloys containing niobium during aging heat treatments lead to an increase in hardness. Addition of W, Nb, and V also increase pitting resistance of the Fe25Ni15Cr austenitic stainless steel. This can be attributed to an increasing level of niobium in the matrix.

Structural, electronic and elastic properties of heavy fermion YbRh2 Laves phase compound

NASA Astrophysics Data System (ADS)

Pawar, Harsha; Shugani, Mani; Aynyas, Mahendra; Sanyal, Sankar P.

2018-05-01

The structural, electronic and elastic properties of YbRh2 Laves phase intermetallic compound which crystallize in cubic (MgCu2-type) structure have been investigated using ab-initio full potential linearized augmented plane wave (FP- LAPW) method with LDA and LDA+U approximation. The calculated ground state properties such as lattice parameter (a0), bulk modulus (B) and its pressure derivative (B') are in good agreement with available experimental and theoretical data. The electronic properties are analyzed from band structures and density of states. Elastic constants are predicted first time for this compound which obeys the stability criteria for cubic system.

Magnetostructural phase transitions and magnetocaloric effect in Tb-Dy-Ho-Co-Al alloys with a Laves phase structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tereshina, I. S., E-mail: irina-tereshina@mail.ru; Baikov Institute of Metallurgy and Material Sciences, Russian Academy of Sciences, Moscow 119991; International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw 53-421

2016-07-07

The influence of simultaneous substitution within the rare earth (R) and Co sublattices on the structural, magnetic, and magnetocaloric properties of the Laves phase RCo{sub 2}-type compounds is studied. Main attention is devoted to the studies of the magnetostructural phase transitions and the transition types with respect to the alloy composition. Multicomponent alloys Tb{sub x}(Dy{sub 0.5}Ho{sub 0.5}){sub 1−x}Co{sub 2} and Tb{sub x}(Dy{sub 0.5}Ho{sub 0.5}){sub 1−x}Co{sub 1.75}Al{sub 0.25} were prepared with the use of high purity metals. Majority of the Tb{sub x}(Dy{sub 0.5}Ho{sub 0.5}){sub 1−x}Co{sub 2} alloys exhibit magnetic transitions of the first-order type and a large magnetocaloric effect. The substitutionmore » of Al for Co in Tb{sub x}(Dy{sub 0.5}Ho{sub 0.5}){sub 1−x}Co{sub 2} increases the Curie temperature (T{sub C}) but changes the transition type from first-to the second-order. The discussion of the physical mechanisms behind the observed phenomena is given on the basis of the first principles electronic-structure calculations taking into account both the atomic disorder and the magnetic disorder effects at finite temperatures. The advantage of Al-containing materials is that sufficiently high magnetocaloric effect values are preserved at T > T{sub C}.« less

Characterization of α-Fe-Free Heteroepitaxial NdFe12- x Ti x Thin-Film Materials with a Novel Cubic Laves Fe2Ti Phase

NASA Astrophysics Data System (ADS)

Hadorn, Jason Paul; Hirayama, Yusuke; Ohkubo, Tadakatsu

2018-01-01

Thin films with compositions of NdFe12 and NdFe11Ti1 were fabricated on W-buffered MgO(001) substrates of varying roughness. In this study, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the films microstructurally, chemically, and crystallographically. This study revealed successful heteroepitaxial synthesis of the tetragonal NdFe12 and NdFe12- x Ti x phases in the Ti-free and Ti-containing films, respectively, both with surface-normal c-axis orientation. It also revealed the presence of other phases within the magnetic layer. The NdFe12 films contained many α-Fe particles, which preferentially precipitated at locally rough regions of the W-buffer interface. The NdFe11Ti1 film showed the ubiquitous presence of an Fe2Ti phase, which covered most of the buffer thereby preventing the formation of α-Fe. This phase was determined to have a novel Cu2Mg-type cubic Laves ( C15) crystal structure with fourfold interfacial symmetry, good coherency, and a low mismatch with the W-buffer, thus rendering itself as being an ideal interface for the heteroepitaxial synthesis of NdFe12- x Ti x crystals. It is proposed that successful application of a cubic Fe2Ti underlayer on W can contribute to the development of a fabrication strategy for NdFe12 thin films without the presence of soft magnetic α-Fe.

Precipitation in AISI 316L(N) during creep tests at 550 and 600 °C up to 10 years

NASA Astrophysics Data System (ADS)

Padilha, A. F.; Escriba, D. M.; Materna-Morris, E.; Rieth, M.; Klimenkov, M.

2007-05-01

The precipitation behaviour in the gauge lengths and in the heads of initially solution annealed type 316L(N) austenitic stainless steel specimens tested in creep at 550 and 600 °C for periods of up to 85 000 h has been studied using several metallographic techniques. Three phases were detected: M 23C 6, Laves, and sigma phase. The volume fraction of the precipitated sigma phase was significantly higher than that of carbides and the Laves phase. M 23C 6 carbide precipitation occurred very rapidly and was followed by the sigma and Laves phases formation in the delta ferrite islands. Sigma and Laves phases precipitated at grain boundaries after longer times. Two different mechanisms of sigma phase precipitation have been proposed, one for delta ferrite decomposition and another for grain boundary precipitation. Small quantities of the Laves phase were detected in delta ferrite, at grain boundaries and inside the grains.

Effects of Laves phase particles on recovery and recrystallization behaviors of Nb-containing FeCrAl alloys

DOE PAGES

Sun, Zhiqian; Edmondson, Philip D.; Yamamoto, Yukinori

2017-11-15

The microstructures and mechanical properties of deformed and annealed Nb-containing FeCrAl alloys were investigated. Fine dispersion of Fe 2Nb-type Laves phase particles was observed in the bcc-Fe matrix after applying a thermomechanical treatment, especially along grain/subgrain boundaries, which effectively stabilized the recovered and recrystallized microstructures compared with the Nb-free FeCrAl alloy. The stability of recovered areas increased with Nb content up to 1 wt%. The recrystallized grain structure in Nb-containing FeCrAl alloys consisted of elongated grains along the rolling direction with a weak texture when annealed below 1100 °C. An abnormal relationship between recrystallized grain size and annealing temperature wasmore » found. Microstructural inhomogeneity in the deformed and annealed states was explained based on the Taylor factor. Annealed Nb-containing FeCrAl alloys showed a good combination of strength and ductility, which is desirable for their application as fuel cladding in light-water reactors.« less

Effect of Al content on structure and mechanical properties of the Al{sub x}CrNbTiVZr (x = 0; 0.25; 0.5; 1) high-entropy alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yurchenko, N.Yu.

2016-11-15

In present study, structure and mechanical properties of the Al{sub x}CrNbTiVZr (x = 0; 0.25; 0.5; 1) high-entropy alloys after arc melting and annealing at 1200 °C for 24 h are investigated. The CrNbTiVZr alloy is composed of body centered cubic (bcc) and C15 (face centered cubic) Laves phases while the Al{sub x}CrNbTiVZr (x = 0.25; 0.5; 1) alloys consist of bcc and two C14 (hexagonal close packed) Laves phases with different chemical compositions. Thermodynamic modeling predicts existence of two phases – bcc and C15 Laves phase and broadening of single bcc phase field due to Al addition. The densitymore » of the alloys decreases with the increase of Al content. The alloys are found to be extremely brittle at room temperature and 600 °C. The alloys have high strength at temperatures of 800–1000 °C. For example, yield strength at 800 °C increases from 440 MPa for the CrNbTiVZr alloy to 1250 MPa for the AlCrNbTiVZr alloy. The experimental phase composition of the Al{sub x}CrNbTiVZr alloys is compared with predicted equilibrium phases and the factors governing the transformation of C15 to C14 Laves phases due to Al addition to the CrNbTiVZr alloy analyzed. Specific properties of the alloys are compared with other high-entropy alloys and commercial Ni-based superalloys. - Highlights: •Al{sub x}CrNbTiVZr (x = 0; 0.25; 0.5; 1) alloys are arc melted and annealed at 1200 °C. •The CrNbTiVZr alloy has bcc and C15 Laves phases. •The Al-containing alloys are composed of bcc and two C14 Laves phases. •The alloys demonstrate high specific strength at temperatures of 800 °C and 1000 °C. •The strength of the alloys increases in proportion with increase of Al content.« less

Dual-phase Cr-Ta alloys for structural applications

DOEpatents

Liu, Chain T.; Brady, Michael P.; Zhu, Jiahong; Tortorelli, Peter F.

2001-01-01

Dual phase alloys of chromium containing 2 to 11 atomic percent tantalum with minor amounts of Mo, Cr, Ti, Y, La, Cr, Si and Ge are disclosed. These alloys contain two phases including Laves phase and Cr-rich solid solution in either eutectic structures or dispersed Laves phase particles in the Cr-rich solid solution matrix. The alloys have superior mechanical properties at high temperature and good oxidation resistance when heated to above 1000.degree. C. in air.

Magnetostriction of some rare earth-aluminum Laves phase compounds

NASA Technical Reports Server (NTRS)

Pourarian, F.; Wallace, W. E.

1979-01-01

Measurements of the linear and volume magnetostriction of RAl2 cubic Laves compounds in which R is one of the rare earth elements Gd, Dy, Ho or Er, at temperatures between 4.2 K and the Curie temperature of each compound, are reported. Magnetic fields up to 2.5 Tesla were applied, and magnetostriction was measured using standard strain gage techniques. Saturation magnetostrictions of 17 x 10 to the -6th, -1420 x 10 to the -6th, 60 x 10 to the -6th and -920 x 10 to the -6th are determined at 4.2 K for GdAl2, DyAl2, HoAl2 and ErAl2, respectively. Large forced magnetostriction is observed in GdAl2 above the saturation field and the strain temperature dependence shows a decrease in magnitude below 40 K. A linear dependence of magnetostriction on magnetic field was observed for DyAl2 above 40 K, and the observed temperature dependence is interpreted in terms of the lowest order single-ion magnetoelastic theory. An observed decrease in the magnitude of the strain of HoAl2 below 15 K is associated with a change of the easy direction of magnetization, while in the case of ErAl2, magnetostriction is observed to occur normally up to the Curie temperature. Large volume magnetostriction is obtained for all the compounds with the exception of GdAl2.

Examination of Multiphase (Zr,Ti)(V,Cr,Mn,Ni)2 Ni-MH Electrode Alloys: Part I. Dendritic Solidification Structure

NASA Astrophysics Data System (ADS)

Boettinger, W. J.; Newbury, D. E.; Wang, K.; Bendersky, L. A.; Chiu, C.; Kattner, U. R.; Young, K.; Chao, B.

2010-08-01

The solidification microstructures of three nine-element Zr-Ni-based AB2 type C14/C15 Laves hydrogen storage alloys are determined. The selected compositions represent a class of alloys being examined for usage as an MH electrode in nickel metal-hydride batteries that often have their best properties in the cast state. Solidification is accomplished by dendritic growth of hexagonal C14 Laves phase, peritectic solidification of cubic C15 Laves phase, and formation of cubic B2 phase in the interdendritic regions. The B2 phase decomposes in the solid state into a complex multivariate platelike structure containing Zr-Ni-rich intermetallics. The observed sequence C14/C15 upon solidification agrees with predictions using effective compositions and thermodynamic assessments of the ternary systems, Ni-Cr-Zr and Cr-Ti-Zr. Experimentally, the closeness of the compositions of the C14 and C15 phases required the use of compositional mapping with an energy dispersive detector capable of processing a very high X-ray flux to locate regions in the microstructure for quantitative composition measurement and transmission electron microscope examination.

Structural, Electronic and Elastic Properties of Heavy Fermion YbTM2 (TM= Ir and Pt) Laves Phase Compounds

NASA Astrophysics Data System (ADS)

Pawar, H.; Shugani, M.; Aynyas, M.; Sanyal, S. P.

2018-02-01

The structural, electronic and elastic properties of YbTM2 (TM = Ir and Pt) Laves phase intermetallic compounds which crystallize in cubic (MgCu2-type) structure, have been investigated using ab-initio full potential linearized augmented plane wave (FP-LAPW) method with LDA and LDA+U approximation. The calculated ground state properties such as lattice parameter (a0), bulk modulus (B) and its pressure derivative (B‧) are in good agreement with available experimental and theoretical data. The electronic properties are analyzed from band structures and density of states. Elastic constants are predicted first time for these compounds which obey the stability criteria for cubic system.

Predictions of thermomagnetic properties of Laves phase compounds: TbAl2, GdAl2 and SmAl2 performed with ATOMIC MATTERS MFA computation system

NASA Astrophysics Data System (ADS)

Michalski, Rafał; Zygadło, Jakub

2018-04-01

Recent calculations of properties of TbAl2 GdAl2 and SmAl2 single crystals, performed with our new computation system called ATOMIC MATTERS MFA are presented. We applied localized electron approach to describe the thermal evolution of Fine Electronic Structure of Tb3+, Gd3+ and Sm3+ ions over a wide temperature range and estimate Magnetocaloric Effect (MCE). Thermomagnetic properties of TbAl2, GdAl2 and SmAl2 were calculated based on the fine electronic structure of the 4f8, 4f7 and 4f5 electronic configuration of the Tb3+ and Gd3+ and Sm3+ ions, respectively. Our calculations yielded: magnetic moment value and direction; single-crystalline magnetization curves in zero field and in external magnetic field applied in various directions m(T,Bext); the 4f-electronic components of specific heat c4f(T,Bext); and temperature dependence of the magnetic entropy and isothermal entropy change with external magnetic field - ΔS(T,Bext). The cubic universal CEF parameters values used for all CEF calculations was taken from literature and recalculated for universal cubic parameters set for the RAl2 series: A4 = +7.164 Ka04 and A6 = -1.038 Ka06. Magnetic properties were found to be anisotropic due to cubic Laves phase C15 crystal structure symmetry. These studies reveal the importance of multipolar charge interactions when describing thermomagnetic properties of real 4f electronic systems and the effectiveness of an applied self-consistent molecular field in calculations for magnetic phase transition simulation.

Alloying and Properties of C14-NbCr₂ and A15-Nb₃X (X = Al, Ge, Si, Sn) in Nb-Silicide-Based Alloys.

PubMed

Tsakiropoulos, Panos

2018-03-07

The oxidation of Nb-silicide-based alloys is improved with Al, Cr, Ge or Sn addition(s). Depending on addition(s) and its(their) concentration(s), alloyed C14-AB₂ Laves and A15-A₃X phases can be stable in the microstructures of the alloys. In both phases, A is the transition metal(s), and B and X respectively can be Cr, Al, Ge, Si or Sn, and Al, Ge, Si or Sn. The alloying, creep and hardness of these phases were studied using the composition weighted differences in electronegativity (∆χ), average valence electron concentrations (VEC) and atomic sizes. For the Laves phase (i) the VEC and ∆χ were in the ranges 4.976 < VEC < 5.358 and -0.503 < ∆χ < -0.107; (ii) the concentration of B (=Al + Cr + Ge + Si + Sn) varied from 50.9 to 64.5 at %; and (iii) the Cr concentration was in the range of 35.8 < Cr < 51.6 at %. Maps of ∆χ versus Cr, ∆χ versus VEC, and VEC versus atomic size separated the alloying behaviours of the elements. Compared with unalloyed NbCr₂, the VEC decreased and ∆χ increased in Nb(Cr,Si)₂, and the changes in both parameters increased when Nb was substituted by Ti, and Cr by Si and Al, or Si and Ge, or Si and Sn. For the A15 phase (i) the VEC and ∆χ were in the ranges 4.38 < VEC < 4.89 and 0.857 < ∆χ < 1.04, with no VEC values between 4.63 and 4.72 and (ii) the concentration of X (=Al + Ge + Si + Sn) varied from 16.3 to 22.7 at %. The VEC versus ∆χ map separated the alloying behaviours of elements. The hardness of A15-Nb₃X was correlated with the parameters ∆χ and VEC. The hardness increased with increases in ∆χ and VEC. Compared with Nb₃Sn, the ∆χ and hardness of Nb₃(Si,Sn) increased. The substitution of Nb by Cr had the same effect on ∆χ and hardness as Hf or Ti. The ∆χ and hardness increased with Ti concentration. The addition of Al in Nb₃(Si,Sn,Al) decreased the ∆χ and increased the hardness. When Ti and Hf, or Ti, Hf and Cr, were simultaneously present with Al, the ∆χ was decreased and

Size versus electronic factors in transition metal carbide and TCP phase stability

NASA Astrophysics Data System (ADS)

Pettifor, D. G.; Seiser, B.; Margine, E. R.; Kolmogorov, A. N.; Drautz, R.

2013-09-01

The contributions of atomic size and electronic factors to the structural stability of transition metal carbides and topologically close-packed (TCP) phases are investigated. The hard-sphere model that has been used by Cottrell to rationalize the occurrence of the octahedral and trigonal local coordination polyhedra within the transition metal carbides is shown to have limitations in TiC since density functional theory (DFT) predicts that the second most metastable phase closest to the B1 (NaCl) ground state takes the B? (BN) structure type with 5-atom local coordination polyhedra with very short Ti-C bond lengths. The importance of electronic factors in the TCP phases is demonstrated by DFT predictions that the A15, ? and ? phases are stabilized between groups VI and VII of the elemental transition metals, whereas the ? and Laves phases are destabilized. The origin of this difference is related to the bimodal shape parameter of the electronic density of states by using the bond-order potential expansion of the structural energy within a canonical tight-binding model. The importance of the size factor in the TCP phases is illustrated by the DFT heats of formation for the binary systems Mo-Re, Mo-Ru, Nb-Re and Nb-Ru which show that the ? and Laves phases become more and more stable compared to A15, ? and ? as the size factor increases from Mo-Re through to Nb-Ru.

Investigation of the physical properties of two Laves phase compounds HRh2 (H = Ca and La): A DFT study

NASA Astrophysics Data System (ADS)

Rahaman, Md. Zahidur; Rahman, Md. Atikur

2018-05-01

By using the first-principle calculations, the structural, elastic, electronic and optical properties of Laves phase intermetallic compounds CaRh2 and LaRh2 prototype with MgCu2 are investigated. The evaluated lattice parameters are consistent with the experimental values. The important elastic properties, such as bulk modulus B, shear modulus G, Young’s modulus Y and the Poisson’s ratio v, are computed by applying the Voigt-Reuss-Hill (VRH) approximation. The analysis of Pugh’s ratio exhibits the ductile nature of both the phases. Electronic conductivity is predicted for both the compounds. Most of the contribution comes from Rh-4d states. The study of bonding characteristics reveals the existence of ionic and metallic bonds in both intermetallics. The study of optical properties indicates that CaRh2 is a better dielectric material than LaRh2. Absorption quality of both the phases is good in the ultraviolet region.

Thermal stability of intermetallic phases in Fe-rich Fe-Cr-Ni-Mo alloys

DOE PAGES

Yang, Ying; Tan, Lizhen; Busby, Jeremy T.

2015-06-12

Understanding the stability of precipitate phases in the Fe-rich Fe-Cr-Ni-Mo alloys is critical to the alloy design and application of Mo-containing Austenitic steels. Coupled with thermodynamic modeling, stability of the chi and Laves phases in two Fe-Cr-Ni-Mo alloys were investigated at 1000, 850 and 700 °C for different annealing time. The morphologies, compositions and crystal structures of the matrix and precipitate phases were carefully examined by Scanning Electron Microscopy, Electron Probe Microanalysis, X-ray diffraction and Transmission Electron Microscopy. The two key findings resulted from this work. One is that the chi phase is stable at high temperature and transformed intomore » the Laves phase at low temperature. The other is that both the chi and Laves phases have large solubilites of Cr, Mo and Ni, among which the Mo solubility has a major role on the relative stability of the precipitate phases. The developed thermodynamic models were then applied to evaluating the Mo effect on the stability of precipitate phases in AISI 316 and NF709 alloys.« less

Alloying and Properties of C14–NbCr2 and A15–Nb3X (X = Al, Ge, Si, Sn) in Nb–Silicide-Based Alloys

PubMed Central

Tsakiropoulos, Panos

2018-01-01

The oxidation of Nb–silicide-based alloys is improved with Al, Cr, Ge or Sn addition(s). Depending on addition(s) and its(their) concentration(s), alloyed C14-AB2 Laves and A15-A3X phases can be stable in the microstructures of the alloys. In both phases, A is the transition metal(s), and B and X respectively can be Cr, Al, Ge, Si or Sn, and Al, Ge, Si or Sn. The alloying, creep and hardness of these phases were studied using the composition weighted differences in electronegativity (∆χ), average valence electron concentrations (VEC) and atomic sizes. For the Laves phase (i) the VEC and ∆χ were in the ranges 4.976 < VEC < 5.358 and −0.503 < ∆χ < −0.107; (ii) the concentration of B (=Al + Cr + Ge + Si + Sn) varied from 50.9 to 64.5 at %; and (iii) the Cr concentration was in the range of 35.8 < Cr < 51.6 at %. Maps of ∆χ versus Cr, ∆χ versus VEC, and VEC versus atomic size separated the alloying behaviours of the elements. Compared with unalloyed NbCr2, the VEC decreased and ∆χ increased in Nb(Cr,Si)2, and the changes in both parameters increased when Nb was substituted by Ti, and Cr by Si and Al, or Si and Ge, or Si and Sn. For the A15 phase (i) the VEC and ∆χ were in the ranges 4.38 < VEC < 4.89 and 0.857 < ∆χ < 1.04, with no VEC values between 4.63 and 4.72 and (ii) the concentration of X (=Al + Ge + Si + Sn) varied from 16.3 to 22.7 at %. The VEC versus ∆χ map separated the alloying behaviours of elements. The hardness of A15-Nb3X was correlated with the parameters ∆χ and VEC. The hardness increased with increases in ∆χ and VEC. Compared with Nb3Sn, the ∆χ and hardness of Nb3(Si,Sn) increased. The substitution of Nb by Cr had the same effect on ∆χ and hardness as Hf or Ti. The ∆χ and hardness increased with Ti concentration. The addition of Al in Nb3(Si,Sn,Al) decreased the ∆χ and increased the hardness. When Ti and Hf, or Ti, Hf and Cr, were simultaneously present with Al, the ∆χ was decreased and the

Local magnetic moment formation at 119Sn Mössbauer impurity in RCo2 (R=Gd,Tb,Dy,Ho,Er) Laves phase compounds

NASA Astrophysics Data System (ADS)

de Oliveira, A. L.; de Oliveira, N. A.; Troper, A.

2008-04-01

In this work, we theoretically study the local magnetic moment formation and the systematics of the magnetic hyperfine fields at a Mösbauer Sn119 impurity diluted at the R site (R=Gd,Tb,Dy,Ho,Er) of the cubic Laves phase intermetallic compounds RCo2. One considers that the magnetic hyperfine fields have two contributions, (i) the contribution from R ions, calculated via an extended Daniel-Friedel [J. Phys. Chem. Solids 24, 1601 (1963)] model, and (ii) the contribution from the induced magnetic moments arising from the Co neighboring sites. Our calculated self-consistent total magnetic hyperfine fields are in a good agreement with recent experimental data.

Intermediate phases in some rare earth-ruthenium systems

NASA Technical Reports Server (NTRS)

Sharifrazi, P.; Raman, A.; Mohanty, R. C.

1984-01-01

The phase equilibria and crystal structures of intermediate phases were investigated in eight representative RE-Ru systems using powder X-ray diffraction and metallographic techniques. The Fe3C, Mn5C2 and Er5Ru3 structures occur in all but the Ce-Ru systems. Phases analogous to Er5Ru3 possess an unknown crystal structure similar to Er5Rh3(I). MgCu2 and MgZn2 type Laves phases are encountered in the light rare earth and heavy rare earth systems, respectively, and RERu2 phases, where RE = Nd and Sm, possess both the Laves phase structures. An intermediate phase, NdRu, with an unknown structure, occurs only in the Nd-Ru system. A bcc structure with 40 atoms per unit cell is encountered in the phases Er3Ru2 and Y3Ru2. The behavior of cerium in Ce-Ru alloys is unique in that four unidentified structures, not encountered in other RE-Ru systems, have been encountered. Also a phase designated as Ce3Ru is found with the Th7Fe3 type structure.

Microstructures and Mechanical Properties of Two-Phase Alloys Based on NbCr(2)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cady, C.M.; Chen, K.C.; Kotula, P.G.

A two-phase, Nb-Cr-Ti alloy (bee+ C15 Laves phase) has been developed using several alloy design methodologies. In effort to understand processing-microstructure-property relationships, diffment processing routes were employed. The resulting microstructure and mechanical properties are discussed and compared. Plasma arc-melted samples served to establish baseline, . . . as-cast properties. In addition, a novel processing technique, involving decomposition of a supersaturated and metastable precursor phase during hot isostatic pressing (HIP), was used to produce a refined, equilibrium two-phase microstructure. Quasi-static compression tests as a ~ function of temperature were performed on both alloy types. Different deformation mechanisms were encountered based uponmore » temperature and microstructure.« less

Computational thermodynamics aided design of novel ferritic alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Ying; Chen, Tianyi; Tan, Lizhen

With the aid of computational thermodynamics, Ni was identified to suppress the liquidus temperature of Fe 2Zr and four Fe-Cr-Ni-Zr alloys were designed to study the Ni effect on the phase stability of Fe 2Zr laves_phase. These alloys were fabricated through traditional arc-metling, followed by annealing at 1000 C for 336 hours and 700 C for 1275 hours. The microstructure were examined and characterized by SEM BSE image, EDS compositional mapping and point scan, XRD and TEM analysis. The major results were summarized below: 1)For investigated alloys with 12wt% Cr, 3~6wt% Zr and 3~9 wt%Ni, the phases in equilibrium withmore » the BCC phase are C15_Laves phase, Fe 23Zr 6 phase. The volume fraction of intermetallic phases increases with Ni and Zr contents. 2)Instead of (Fe,Cr) 2Zr C14_Laves phase, Ni stabilizes the C15_Laves structure in Fe-Cr-Ni-Zr alloys by substituting Fe and Cr atoms with Ni atoms in the first sublattice. 3)Fe 23Zr 6, that is metastable in the Fe-Cr-Zr ternary, is also stabilized by Ni addition. 4)Ni 7Zr 2 phase was observed in samples with high Ni/Zr ratio. Extensive solubility of Fe was identified in the phase. The microstructural and composition results obtained from this study will be incorportated into the the Fe-Cr-Ni-Zr database. The current samples will be subjected to ion irradiaition to be compared with those results for Fe-Cr-Zr alloys. Additional alloys will be designed to form (Fe,Cr,Ni) 2Zr nanoprecipitates for further studies.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, S.; Yang, M.; Song, X.L.

The Laves phase precipitation process was characterised by means of field emission scanning electron microscopy to demonstrate its effect on creep rupture strength of steels with a fully ferritic matrix. To eliminate the effects of carbide and carbonitride precipitations so that the creep rupture data can be analysed exclusively in relation to the Laves phase precipitation process, an alloy Fe–9Cr–3Co–3W (wt.%) without C and N additions was used for the study. Creep rupture strengths were measured and volume fraction and particle size of Laves phase precipitates in the ruptured specimens were analysed. It was found that the creep rupture strengthmore » started to collapse (or decrease more rapidly) long before the Laves phase precipitation reached equilibrium fraction. This was related to the onset of the coarsening of Laves phase particles, which precipitated only on grain boundaries and hence contributed little to precipitation strengthening. Creep deformation had no effect either on the precipitation kinetics or on the growth kinetics of Laves phase particles. - Highlights: • Laves phase precipitation at 650 °C was characterised for Fe–9Cr–3W–3Co alloy. • Laves phase precipitated predominantly on grain boundaries. • Creep deformation had no effect on Laves phase precipitation and growth kinetics. • Creep strength started to collapse long before Laves phase precipitation is ended. • Collapse of creep strength was attributed to the coarsening of Laves phase particles.« less

Local magnetic moment formation at 119Sn Mössbauer impurity in RFe2 ( R=rare-earth metals) Laves phases compounds

NASA Astrophysics Data System (ADS)

de Oliveira, A. L.; de Oliveira, N. A.; Troper, A.

2010-05-01

The purpose of the present work is to theoretically study the local magnetic moment formation and the systematics of the magnetic hyperfine fields at a non-magnetic s-p Mössbauer 119Sn impurity diluted on R sites ( R=rare-earth metals) of the cubic Laves phases intermetallic compounds RFe2. One considers that the magnetic hyperfine field has two contributions (i) the contribution from R ions, calculated via an extended Daniel-Friedel [J. Phys. Chem. Solids 24 (1963) 1601] model and (ii) the contribution from the induced magnetic moments arising from the Fe neighboring sites. We have in this case a two-center Blandin-Campbell-like [Phys. Rev. Lett. 31 (1973) 51; J. Magn. Magn. Mater. 1 (1975) 1] problem, where a magnetic 3d-element located at a distance from the 119Sn impurity gives an extra magnetization to a polarized electron gas which is strongly charge perturbed at the 119Sn impurity site. We also include in the model, the nearest-neighbor perturbation due to the translational invariance breaking introduced by the impurity. Our self-consistent total magnetic hyperfine field calculations are in a very good agreement with recent experimental data.

Simple shearing flow of dry soap foams with tetrahedrally close-packed structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reinelt, Douglas A.; Kraynik, Andrew M.

2000-05-01

The microrheology of dry soap foams subjected to quasistatic, simple shearing flow is analyzed. Two different monodisperse foams with tetrahedrally close-packed (TCP) structure are examined: Weaire-Phelan (A15) and Friauf-Laves (C15). The elastic-plastic response is evaluated by using the Surface Evolver to calculate foam structures that minimize total surface area at each value of strain. The foam geometry and macroscopic stress are piecewise continuous functions of strain. The stress scales as T/V{sup 1/3}, where T is surface tension and V is cell volume. Each discontinuity corresponds to large changes in foam geometry and topology that restore equilibrium to unstable configurations thatmore » violate Plateau's laws. The instabilities occur when the length of an edge on a polyhedral foam cell vanishes. The length can tend to zero smoothly or abruptly with strain. The abrupt case occurs when a small increase in strain changes the energy profile in the neighborhood of a foam structure from a local minimum to a saddle point, which can lead to symmetry-breaking bifurcations. In general, the new structure associated with each stable solution branch results from an avalanche of local topology changes called T1 transitions. Each T1 cascade produces different cell neighbors, reduces surface energy, and provides an irreversible, film-level mechanism for plastic yield behavior. Stress-strain curves and average stresses are evaluated by examining foam orientations that admit strain-periodic behavior. For some orientations, the deformation cycle includes Kelvin cells instead of the original TCP structure; but the foam does not remain perfectly ordered. Bifurcations during subsequent T1 cascades lead to disorder and can even cause strain localization. (c) 2000 Society of Rheology.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shassere, Benjamin; Yamamoto, Yukinori; Poplawsky, Jonathan

We have develooped a new Fe-Cr-Al (FCA) alloy system with good oxidation resistance and creep strength at high temperature. The alloy system is a candidate for use in future fossil-fueled power plants. The creep strength of these alloys at 973 K (700 °C) was found to be comparable with traditional 9 pct Cr ferritic–martensitic steels. A few FCA alloys with general composition of Fe-30Cr-3Al-.2Si-xNb (x = 0, 1, or 2) with a ferrite matrix and Fe 2Nb-type Laves precipitates were prepared. The detailed microstructural characterization of samples, before and after creep rupture testing, indicated precipitation of the Laves phase withinmore » the matrix, Laves phase at the grain boundaries, and a 0.5 to 1.5 μm wide precipitate-free zone (PFZ) parallel to all the grain boundaries. In these alloys, the areal fraction of grain boundary Laves phase and the width of the PFZ controlled the cavitation nucleation and eventual grain boundary ductile failure. Finally, we used a phenomenological model to compare the creep strain rates controlled by the effects of the particles on the dislocations within the grain and at grain boundaries. (The research sponsored by US-DOE, Office of Fossil Energy, the Crosscutting Research Program).« less

Thermochemistry analyses for transformation of C6 glucose compound into C9, C12 and C15 alkanes using density functional theory

NASA Astrophysics Data System (ADS)

Verma, Anand Mohan; Kishore, Nanda

2017-02-01

The hydrolysis of cellulose fraction of biomass yields C6 glucose which further can be transformed into long-chain hydrocarbons by C-C coupling. In this study, C6 glucose is transformed into three chain alkanes, namely, C9, C12 and C15 using C-C coupling reactions under the gas and aqueous phase milieus. The geometry optimisation and vibrational frequency calculations are carried out at well-known hybrid-GGA functional, B3LYP with the basis set of 6-31+g(d,p) under the density functional theory framework. The single point energetics are calculated at M05-2X/6-311+g(3df,2p) level of theory. All thermochemical properties are calculated over a wide range of temperature between 300 and 900 K at an interval of 100 K. The thermochemistry suggested that the aqueous phase behaviour is suitable for the hydrolysis of sugar into long-chain alkanes compared to gas-phase environment. The hydrodeoxygenation reactions under each reaction pathway are found as most favourable reactions in both phases; however, aqueous phase dominates over gas phase in all discussed thermodynamic parameters.

The crystal structure of the mixed-layer Aurivillius phase Bi 5Ti 1.5W 1.5O 15

NASA Astrophysics Data System (ADS)

Tellier, J.; Boullay, Ph.; Créon, N.; Mercurio, D.

2005-09-01

The crystal structure of the 1+2 mixed-layer Aurivillius phase Bi 5Ti 1.5W 1.5O 15 (SG I2cm n o 46: -cba, Z=4, a=5.4092(3) Å, b=5.3843(3) Å and c=41.529(3) Å) consisting of the ordered intergrowth of one and two octahedra thick perovskite-type blocks separated by [Bi 2O 2] 2+ slabs is reported. Supported by an electron diffraction investigation and, using the Rietveld analysis, it is shown that this compound should be described using a I-centering lattice in agreement with the generalised structural model of the Aurivillius type compounds recently presented by the authors. The structure of this Bi 5Ti 1.5W 1.5O 15 phase is analyzed in comparison with the related simple members (Bi 2WO 6 and Bi 3Ti 1.5W 0.5O 9). The crystal structure of Bi 3Ti 1.5W 0.5O 9 is also reported.

Accelerated Exploration of Multi-principal Element Alloys for Structural Applications (Postprint)

DTIC Science & Technology

2015-04-27

SS phases (BCC, HCP and FCC), three silicide phases (M5Si3, M5Si4 and M3Si3), an ordered B2 phase, and two Laves phases (C14 and C15). In total, 453...alloys containing silicide phases (M5Si3, M5Si4, and M3Si2) is probably due to very negative, often below 50 kJ/mol [51 53] enthalpies of formation of...The majority of equiatomic alloys containing two or more phases are (SSþ IM) alloys.5. BCC, HCP and FCC SS phases, three silicide phases (M5Si3, M5Si4

Microstructural changes in cast martensitic steel after creep at 620°C

NASA Astrophysics Data System (ADS)

Borisova, Yu. I.; Dudko, V. A.; Skorobogatykh, V. N.; Shchenkova, I. A.; Kaibyshev, R. O.

2017-10-01

Microstructural changes in the cast steel GX12CrMoWVNbN10-1-1 (Fe-0.11 C-0.31 Si-0.89 Mn-9.57 Cr-0.66 Ni-1.01 Mo-1.00 W-0.21 V-0.06 Nb-0.05 Cu-0.05 N in wt %) have been investigated after tests for long-term strength at a temperature of 620°C in the range of stresses of 120-160 MPa. Upon short-term creep (up to 5000 h), the tempered troostite structure and distribution of particles of proeutectoid constituents change insignificantly, except for the precipitation of particles of the Laves phase ˜100 nm in size along boundaries of laths, blocks, packets, and initial austenite grains. Upon long-term creep (to 10000 h), the tempered troostite partially transforms into the subgrain structure, which is accompanied by a decrease in the dislocation density from 6.4 × 1014 to 3.1 × 1013 m-2 and connected with growth of sizes of M23C6 carbides of 105-150 nm and particles of the Laves phase to 380 nm, due to the dissolution of these particles located along path boundaries. Upon long-term creep, the average size of V(C,N) particles increases from 45 to 64 nm (while Nb(C,N) particles increase from 48 to 87 nm), and the Nb content in V-enriched carbonitrides and the V content in Nb-enriched M(C,N) particles substantially decrease. No formation of the Z phase has been revealed. The combination of M(C,N) nanoparticles with the presence of W in the solid solution has been found to be responsible for the enhanced high-temperature strength of the steel.

The Effect of Boron and Zirconium on the Structure and Tensile Properties of the Cast Nickel-Based Superalloy ATI 718Plus

NASA Astrophysics Data System (ADS)

Hosseini, Seyed Ali; Abbasi, Seyed Mehdi; Madar, Karim Zangeneh

2018-04-01

The effects of boron and zirconium on cast structure, hardness, and tensile properties of the nickel-based superalloy 718Plus were investigated. For this purpose, five alloys with different contents of boron and zirconium were cast via vacuum induction melting and then purified via vacuum arc remelting. Microstructural analysis by light-optical microscope and scanning electron microscope equipped with energy-dispersive x-ray spectroscopy and phase studies by x-ray diffraction analysis were performed. The results showed that boron and zirconium tend to significantly reduce dendritic arm spacing and increase the amount of Laves, Laves/gamma eutectic, and carbide phases. It was also found that boron led to the formation of B4C and (Cr, Fe, Mo, Ni, Ti)3B2 phases and zirconium led to the formation of intermetallic phases and ZrC carbide. In the presence of boron and zirconium, the hardness and its difference between dendritic branches and inter-dendritic spaces increased by concentrating such phases as Laves in the inter-dendritic spaces. These elements had a negative effect on tensile properties of the alloy, including ductility and strength, mainly because of the increase in the Laves phase. It should be noted that the largest degradation of the tensile properties occurred in the alloys containing the maximum amount of zirconium.

Superstructure and physical properties of skutterudite-related phase CoGe1.5Se1.5

NASA Astrophysics Data System (ADS)

Liang, Y.; Fang, B.; Zhu, X. M.; Liang, M. M.

2017-03-01

CoGe1.5Se1.5 skutterudite-related phase with a homogeneity range has been synthesized by solid-state reaction. The phase purity, homogeneity range, crystal structure, thermal stability and electrical resistivity were studied. XRD data indicates that CoGe1.5Se1.5 crystallized in a modification of the skutterudite CoAs3 type structure with space group R\\bar{3} (a = b = 11.751(1) Å, c = 14.36(1) Å). HRTEM-SAED shows more information about the superstructure to confirm the rhombohedral symmetry with space group R\\bar{3}. The lattice parameter of this skutterudite-related phase was found to be dependent on the concentration of Ge and Se. CoGe1.5Se1.5 decomposed between 1073 K and 1173 K under argon atmosphere investigated by in-situ XRD, suggesting a good thermal stability. CoGe1.49Se1.42, CoGe1.43Se1.34 and CoGe1.50Se1.15 dense bulk samples were obtained by hot-press technique. The chemical composition detected by FESEM/EDS suggests the homogeneity range and the existence of voids at framework positions. The electrical resistivity of the compounds decreases with increasing temperature, acting as a semiconductor. The chemical composition has a big influence on the value of electrical resistivity and energy gap.

Creep and precipitation behaviors of AL6XN austenitic steel at elevated temperatures

NASA Astrophysics Data System (ADS)

Meng, L. J.; Sun, J.; Xing, H.

2012-08-01

Creep behaviors of the solution-treated AL6XN austenitic stainless steel have been investigated at 873-1023 K and 120-260 MPa. The results showed that the creep stress exponent and activation energy of the AL6XN steel are 5 and 395.4 kJ/mol, respectively in the power-law breakdown regime. TEM observations revealed that dislocations distributed homogenously in grains. The creep deformation mechanism is mainly attributed to viscous dislocation glide. Precipitates in the steel after creep deformation were additionally analyzed by TEM, and the results showed that there are four different types of precipitates, such as M23C6, M6C, σ phase and Laves phase. The M23C6 carbides were observed at grain boundaries in the steel after creep at 873 K. The M6C, σ phase and Laves phase precipitates were found when the creep temperature increases to 923-1023 K. Although the AL6XN steel exhibited low steady state creep rates, a high volume fraction of brittle precipitates of σ and Laves phases reduced the creep lifetime of the steel at elevated temperatures.

Spin reorientation and magnetoelastic properties of ferromagnetic T b1 -xN dxC o2 systems with a morphotropic phase boundary

NASA Astrophysics Data System (ADS)

Murtaza, Adil; Yang, Sen; Chang, Tieyan; Ghani, Awais; Khan, Muhammad Tahir; Zhang, Rui; Zhou, Chao; Song, Xiaoping; Suchomel, Matthew; Ren, Yang

2018-03-01

The spin reorientation (SR) and magnetoelastic properties of pseudobinary ferromagnetic T b1 -xN dxC o2 (0 ≤x ≤1.0 ) systems involving a morphotropic phase boundary (MPB) were studied by high-resolution synchrotron x-ray diffraction (XRD), magnetization, and magnetostriction measurements. The easy magnetization direction of the Laves phase lies along the 〈111 〉 axis with x <0.65 , whereas it lies along the 〈100 〉 axis for x >0.65 below Curie temperature (TC). The temperature-dependent magnetization curves showed SR; this can be explained by a two-sublattice model. Based on the synchrotron (XRD) and magnetization measurements, the SR phase diagram for a MPB composition of T b0.35N d0.65C o2 was obtained. Contrary to previously reported ferromagnetic systems involving MPB, the MPB composition of T b0.35N d0.65C o2 exhibits a low saturation magnetization (MS), indicating a compensation of the Tb and Nd magnetic moments at MPB. The anisotropic magnetostriction (λS) first decreased until x =0.8 and then continuously increased in the negative direction with further increase of Nd concentration. The decrease in magnetostriction can be attributed to the decrease of spontaneous magnetostriction λ111 and increase of λ100 with opposite sign to λ111. This paper indicates an anomalous type of MPB in the ferromagnetic T b1 -xN dxC o2 system and provides an active way to design novel functional materials with exotic properties.

Simple shearing flow of dry soap foams with TCP structure[Tetrahedrally Close-Packed

DOE Office of Scientific and Technical Information (OSTI.GOV)

REINELT,DOUGLAS A.; KRAYNIK,ANDREW M.

2000-02-16

The microrheology of dry soap foams subjected to large, quasistatic, simple shearing deformations is analyzed. Two different monodisperse foams with tetrahedrally close-packed (TCP) structure are examined: Weaire-Phelan (A15) and Friauf-Laves (C15). The elastic-plastic response is evaluated by calculating foam structures that minimize total surface area at each value of strain. The minimal surfaces are computed with the Surface Evolver program developed by Brakke. The foam geometry and macroscopic stress are piecewise continuous functions of strain. The stress scales as T/V{sup 1/3} where T is surface tension and V is cell volume. Each discontinuity corresponds to large changes in foam geometrymore » and topology that restore equilibrium to unstable configurations that violate Plateau's laws. The instabilities occur when the length of an edge on a polyhedral foam cell vanishes. The length can tend to zero smoothly or abruptly with strain. The abrupt case occurs when a small increase in strain changes the energy profile in the neighborhood of a foam structure from a local minimum to a saddle point, which can lead to symmetry-breaking bifurcations. In general, the new foam topology associated with each stable solution branch results from a cascade of local topology changes called T1 transitions. Each T1 cascade produces different cell neighbors, reduces surface energy, and provides an irreversible, film-level mechanism for plastic yield behavior. Stress-strain curves and average stresses are evaluated by examining foam orientations that admit strain-periodic behavior. For some orientations, the deformation cycle includes Kelvin cells instead of the original TCP structure; but the foam does not remain perfectly ordered. Bifurcations during subsequent T1 cascades lead to disorder and can even cause strain localization.« less

Experimental Investigation and Analytical Prediction of σ-Phase Precipitation in AISI 316L Austenitic Stainless Steel

NASA Astrophysics Data System (ADS)

Sahlaoui, Habib; Sidhom, Habib

2013-07-01

The phase precipitation in industrial AISI 316L stainless steel during aging for up to 80,000 hours between 823 K and 1073 K (550 °C and 800 °C) has been studied using transmission electron microscopy, scanning transmission electron microscopy, and carbon replica energy-dispersive X-ray microanalysis. Three phases were identified: Chromium carbides (M23C6), Laves phase ( η), and σ-phase (Fe-Cr). M23C6 carbide precipitation occurred firstly and was followed by the η and σ-phases at grain boundaries when the aging temperature is higher than 873 K (600 °C). Precipitation and growth of M23C6 create chromium depletion zones at the grain boundaries and also retard the σ-phase formation. Thus, the σ-phase is controlled by the kinetic of chromium bulk diffusion and can appear only when the chromium reaches, at grain boundaries and at the M23C6/ γ and M23C6/ η/ γ interfaces, content higher than a critical value obtained by self-healing. An analytical model, based on equivalent chromium content, has been established in this study and successfully validated to predict the time-temperature-precipitation diagram of the σ-phase. The obtained diagram is in good agreement with the experimental results.

As-Cast Icosashedral Quasicrystals in Ti-Zr-Ni Alloys

NASA Astrophysics Data System (ADS)

Lee, Geun Woo; Gangopadhyay, Anup K.; Kelton, Kenneth F.

2002-03-01

Most Ti-based icosahedral quasicrystals (i-phase) obtained by rapid quenching from the melt are metastable and disordered. In contrast, the Ti-Zr-Ni i-phase prepared by low temperature annealing is stable and better ordered. This i-phase is formed by a solid-state transformation from C14 Laves phase and α (Ti/Zr) solid-solution phase. It has not been possible previously to grow this i-phase directly from the liquid. Here, the nucleation and growth of the i-phase from the liquid in as-cast Ti-Zr-Ni alloys is reported. Pentagonal growth ledges in as-cast Ti-Zr-Ni ingots are clearly observed. Transmission electron microscopy and x-ray diffraction studies confirm the phase identity. Differential scanning calorimetry measurements show an endothermic transformation from the i-phase to a phase mixture of the C14 Laves and solid-solution phases, demonstrating that this i-phase is also stable. The short time that the liquid remains in the Laves phase-forming-field and the higher nucleation rate of the i-phase, owing to the presumed similarity between the local atomic structures of the i-phase and liquid, allows the i-phase to nucleate and grow directly from the liquid. Container-less solidification studies using electrostatic levitation (ESL) techniques support this conclusion.

Dielectric and structural properties of diffuse ferroelectric phase transition in Pb1.85K1.15Li0.15Nb5O15 ceramic

NASA Astrophysics Data System (ADS)

Choukri, E.; Gagou, Y.; Mezzane, D.; Abkhar, Z.; El Moznine, R.; Luk'yanchuk, I.; Saint-Grégoire, P.; Kavokin, A. V.

2011-02-01

We studied the structural and dielectric properties of new Tetragonal Tungsten Bronze (TTB) ceramics Pb1.85K1.15Li0.15Nb5O15 that was synthesized by solid-state reaction. We pay a special attention to the diffuse phase transition (DPT) that occurs close to 425 °C. Using dielectric measurements in a frequency range of 10 Hz-1 MHz and in the temperature range 30-560 °C, we have shown that the real permittivity close to DPT is well described by Santos-Eiras phenomenological model. Space-charge polarization, relaxation phenomena and free charges conductivity have been analyzed using dielectric spectroscopy impedance and modulus characterization. Cole-Cole plots show a non-Debye (polydispersive) type relaxation. In paraelectric phase the Arrhenius activation energy was determined as Eτ = 0.72 eV. We demonstrated that frequency dependence of ac conductivity at different temperatures obeys the Jonscher's universal law: σac = σdc + A(ω)n.

Composition anisotropy compensation and magnetostriction of Co-doped Laves compounds Tb0.2Dy0.8-xPrxFe1.93 (0 ≤ x ≤ 0.40)

NASA Astrophysics Data System (ADS)

Li, F.; Liu, J. J.; Zhu, X. Y.; Shen, W. C.; Lin, L. L.; Du, J.; Si, P. Z.

2018-07-01

Alloys of Tb0.2Dy0.8-xPrx(Fe0.8Co0.2)1.93 (0 ≤ x ≤ 0.40) are arc melted and investigated for structural, magnetic and magnetoelastic properties by means of X-ray diffraction (XRD), a vibrating sample magnetometer and a standard strain technique. The 20 at.% Co substitution for Fe is shown to enable the formation of the single Laves phase with a high Pr content up to x = 0.25. Experimental evidence for magnetocrystalline-anisotropy compensation between Pr3+ and Dy3+ ions is obtained in the Laves phase system. The easy magnetization direction (EMD) at room temperature rotates from <100> to <110> axis when x increases from 0 to 0.40. The linear anisotropic magnetostriction λa (=λ||-λ⊥) increases with increasing Pr content when x ≤ 0.25 ascribed to both the larger magnetostriction of PrFe2 than that of DyFe2 and the decrease of the resulted anisotropy due to compensation. The composition anisotropy compensation is found to be around x = 0.25, shifting to the Pr-rich side at room temperature as compared to the Co-free counterpart Tb0.2Dy0.8-xPrxFe1.93 system. The Tb0.2Dy0.55Pr0.25(Fe0.8Co0.2)1.93 alloy has good magnetoelastic properties at room temperature, that is, a low anisotropy and a high low-field magnetostriction λa ∼140 ppm at 1 kOe.

Modeling the Transition From Predominantly Gas- to Predominantly Aerosol-Phase Products From OH Reactions With the Homologous Series of C10 to C15 n- Alkanes

NASA Astrophysics Data System (ADS)

Jordan, C. E.; Ziemann, P. J.; Griffin, R. J.; Lim, Y. B.; Atkinson, R.; Arey, J.

2006-12-01

Recent laboratory studies have shown significant formation of secondary organic aerosol (SOA) from OH reactions with a homologous series of n-alkanes. SOA mass yields of 56% were observed for pentadecane (C15), while only 0.5% yield was observed from octane (C8, the smallest alkane in the series). A rapid transition in SOA yield is observed from C10 to C13, with SOA yields increasing from 4% to 49%. In standard gas-aerosol partitioning theory, the vapor pressure controls the amount of material that can condense into the particle phase. However, the rapid transition observed here suggests there may also be a shift in the predominant reaction pathways for longer chain alkanes, leading to greater production of lower vapor pressure products. Here we present an investigation of the role of vapor pressure versus the role of shifting branching ratios to test the influence of each of these on SOA mass yields. We have added each of the alkanes in this series to the Caltech Atmospheric Chemistry Mechanism (CACM). This mechanism was developed in part to predict explicitly concentrations of secondary and tertiary semivolatile oxidation products that potentially form SOA. Although it is has been developed to lump similar compounds together for computational efficiency, it is nonetheless easily adapted and ideally suited for a detailed zero-dimensional modeling study of this kind. This gas-phase mechanism is linked to the aerosol partitioning module MPMPO (Model to Predict the Multi- phase Partitioning of Organics). MPMPO is a fully coupled module that allows the simultaneous partitioning of semi-volatile species to both an aqueous and an organic aerosol phase.

Phase Evolution in and Creep Properties of Nb-Rich Nb-Si-Cr Eutectics

NASA Astrophysics Data System (ADS)

Gang, Florian; Kauffmann, Alexander; Heilmaier, Martin

2018-03-01

In this work, the Nb-rich ternary eutectic in the Nb-Si-Cr system has been experimentally determined to be Nb-10.9Si-28.4Cr (in at. pct). The eutectic is composed of three main phases: Nb solid solution (Nbss), β-Cr2Nb, and Nb9(Si,Cr)5. The ternary eutectic microstructure remains stable for several hundred hours at a temperature up to 1473 K (1200 °C). At 1573 K (1300 °C) and above, the silicide phase Nb9(Si,Cr)5 decomposes into α-Nb5Si3, Nbss, and β-Cr2Nb. Under creep conditions at 1473 K (1200 °C), the alloy deforms by dislocation creep while the major creep resistance is provided by the silicide matrix. If the silicide phase is fragmented and, thus, its matrix character is destroyed by prior heat treatment [ e.g., at 1773 K (1500 °C) for 100 hours], creep is mainly controlled by the Laves phase β-Cr2Nb, resulting in increased minimum strain rates. Compared to state of the art Ni-based superalloys, the creep resistance of this three-phase eutectic alloy is significantly higher.

Microstructure and Properties of a Refractory NbCrMo0.5Ta0.5ZrTi Alloy (Preprint)

DTIC Science & Technology

2011-10-01

slightly enriched with Nb , Mo and Ta and depleted with Zr and Cr, and its lattice parameter after HIP was a = 324.76 ± 0.16 pm. The BCC2 phase was...FCC phase was highly enriched with Cr and it was identified as a Laves C15 phase, ( Zr ,Ta)(Cr,Mo, Nb )2, with the lattice parameter a = 733.38 ± 0.18 pm...with Nb , Mo and Ta and depleted with Zr and Cr, and its lattice parameter after HIP was a = 324.76 ± 0.16 pm. The BCC2 phase was enriched with Zr and Ti

Thermal stability and phase transformation in fully indium oxide (InO{sub 1.5}) stabilized zirconia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Piva, R.H., E-mail: honorato.piva@ua.pt; Piva, D.H

2017-01-15

Indium oxide (InO{sub 1.5}) stabilized zirconia (InSZ) is an attractive material as electrolyte, or electrode, in solid oxide fuel cells (SOFCs), and as corrosion resistant top coat in thermal barrier coatings. However, little is known about the phase stability of cubic InSZ at temperatures that simulate the conditions in an operating SOFC or turbine. This article provides an investigation of the phase stability and phase transformations in cubic InSZ after heat treatments at 800, 1000, and 1200 °C for periods up to 2000 h. The results revealed that cubic InSZ is not stable during annealing at 1000 and 1200 °C,more » owing to a fast destabilization of the initial cubic phase to tetragonal, and eventually to monoclinic (c → t → m). The c → t → m transition in InSZ is intimately associated with the indium volatilization. On the other hand, cubic InSZ remained stable for 2000 h at 800 °C, although the partial formation of the tetragonal phase was observed along with a 0.25% contraction in the unit cell volume of the cubic phase, caused by short-range ordering. These results demonstrate that technological applications of cubic InSZ are restricted to temperatures at which the volatilization of the InO{sub 1.5} stabilizer does not occur. - Highlights: •Phase stability of fully InO{sub 1.5} stabilized zirconia (cubic InSZ) was evaluated. •Cubic InSZ is instable at temperatures ≥ 1000 °C, owing to the cubic-to-tetragonal-to-monoclinic destabilization. •Cubic InSZ undergoes the cubic-to-tetragonal transformation at ~ 800 °C. •Owing to the low phase stability, applications of cubic InSZ in TBCs or SOFCs are restricted.« less

Investigation on the optimized heat treatment procedure for laser fabricated IN718 alloy

NASA Astrophysics Data System (ADS)

Zhang, Yaocheng; Yang, Li; Chen, Tingyi; Zhang, Weihui; Huang, Xiwang; Dai, Jun

2017-12-01

The laser fabricated IN718 alloys were prepared by laser cladding system. The microstructure and microhardness of laser fabricated IN718 alloys were investigated after heat treatment. The microstructure and the elevated temperature mechanical properties of laser fabricated IN718 alloys were analyzed. The results showed that the microstructure of laser fabricated IN718 alloy consisted of austenitic matrix and dendritic Laves/γ eutectic. Most all Laves/γ eutectic was dissolved into austenitic matrix, and the complete recrystallization and the large grains occurred in the laser fabricated IN718 alloy after homogenization at 1080-1140 °C for 1 h, the dendritic Laves/γ eutectic was refined and the partial recrystallization occurred during the solid solution at 940-1000 °C for 1.5 h, the microhardness of the double aging (DA) alloys was about more than twice that of as-fabricated IN718 alloy. The recrystallized microstructure was obtained in the heat-treated laser fabricated IN718 alloy after 1100 °C/1 h air cooling (AC), 980 °C/1.5 h (AC), 700 °C/8 h furnace cooling (FC, 100 °C/h) to 600 °C/8 h (AC). The microhardness and the elevated temperature tensile strength were more than twice that of as-fabricated IN718 alloy due to a large concentration of γ″ phase precipitation to improve the transgranular strength and large grain to guarantee the grain boundary strength. The fracture morphologies of as-fabricated and heat-treated laser fabricated IN718 alloys were presented as the fiber dimples, the fracture mechanism of as-fabricated and heat-treated laser fabricated IN718 alloys was ductile fracture.

Self-consistent full-potential linearized-augmented-plane-wave local-density electronic-structure studies of magnetism and superconductivity in C15 compounds: ZrZn2 and ZrV2

NASA Astrophysics Data System (ADS)

Huang, Mei-Chun; Jansen, H. J. F.; Freeman, A. J.

1988-03-01

The electronic structure and properties of the cubic Laves phase (C15) compounds ZrZn2 and ZrV2 have been determined using our all-electron full-potential linearized-augmented-plane-wave (FLAPW) method for bulk solids. The computations were performed in two stages: (i) self-consistent warped muffin tin and (ii) self-consistent full potential. Spin-orbit coupling was included after either stage. The effects of the inclusion of the nonspherical terms inside the muffin tins on the eigenvalues is found to be small (of order 1 mRy). However, due to the fact that some of the bands near the Fermi level are flat, this effect leads to a much higher value of the density of states at EF in ZnZr2. The most important difference between the materials ZrZn2 and ZrV2 is the position of the d bands derived from the Zr and V atoms. Consequently, these materials have completely different Fermi surfaces. We have investigated the magnetic properties of these compounds by evaluating their generalized Stoner factors and found agreement with experiment. Our results for the superconducting transition temperature for these materials is found to be strongly dependent on the spin fluctuation parameter μsp. Of course, because of the magnetic transition, superconductivity cannot be observed in ZnZr2.

Effects of the TiC Nanoparticle on Microstructures and Tensile Properties of Selective Laser Melted IN718/TiC Nanocomposites

NASA Astrophysics Data System (ADS)

Yao, Xiling; Moon, Seung Ki; Lee, Bing Yang; Bi, Guijun

2018-03-01

The purpose of this paper is to investigate the effects of TiC nanoparticle content on microstructures and tensile properties of the IN718/TiC nanocomposites fabricated by selective laser melting (SLM). 0.5wt%, 1.0wt%, and 2.0wt% of TiC nanoparticles are added to the IN718 powders. The bulk-form IN718/TiC nanocomposites with different TiC contents are fabricated in-situ by SLM using the same process settings. The evolution of microstructures and tensile properties as the effect of changing the TiC content is studied using the optical microscopy, scanning electron microscopy, X-ray diffraction analysis, and tensile testing. The increase of TiC content refines the microstructure, promotes the formation of the cellular morphology, and reduces the size and continuity of Laves precipitates. Increasing the TiC content improves the yield strength and ultimate tensile strength but decreases the ductility. The grain refinement, dislocation bowing, dislocation punching, and the reduction in Laves precipitate contribute to the strengthening effect in the IN718/TiC nanocomposites.

Characterization of the Microstructures and the Cryogenic Mechanical Properties of Electron Beam Welded Inconel 718

NASA Astrophysics Data System (ADS)

Kwon, Soon Il; Bae, Sang Hyun; Do, Jeong Hyeon; Jo, Chang Yong; Hong, Hyun Uk

2016-02-01

The microstructures and the cryogenic mechanical properties of electron beam (EB) welds between cast and forged Inconel 718 superalloys with a thickness of 10 mm were investigated in comparison with gas tungsten arc (GTA) welds. EB welding with a heat input lower than 250 J/mm caused the formation of liquation microfissuring in the cast-side heat-affected-zone (HAZ) of the EB welds. HAZ liquation microfissuring appeared to be associated with the constitutional liquation of primary NbC carbides at the grain boundaries. Compared with the GTA welding process, the EB welding produced welds with superior microstructure, exhibiting fine dendritic structure associated with the reduction in size and fraction of the Laves phase due to the rapid cooling rate. This result was responsible for the superior mechanical properties of the EB welds at 77 K (-196 °C). Laves particles in both welds were found to provide the preferential site for the crack initiation and propagation, leading to a significant decrease in the Charpy impact toughness at 77 K (-196 °C). Crack initiation and propagation induced by Charpy impact testing were discussed in terms of the dendrite arm spacing, the Laves size and the dislocation structure ahead of the crack arisen from the fractured Laves phase in the two welds.

Three new HLA-C alleles (HLA-C*14:02:13, HLA-C*15:72 and HLA-C*15:74) in Saudi bone marrow donors.

PubMed

Fakhoury, H A; Jawdat, D; Alaskar, A S; Al Jumah, M; Cereb, N; Hajeer, A H

2015-10-01

Three new HLA-C alleles were identified by sequence-based typing method (SBT) in donors for the Saudi Bone Marrow Donor Registry (SBMDR). HLA-C*14:02:13 differs from HLA-C*14:02:01 by a silent G to A substitution at nucleotide position 400 in exon 2, where lysine at position 66 remains unchanged. HLA-C*15:72 differs from HLA-C*15:22 by a nonsynonymous C to A substitution at nucleotide position 796 in exon 3, resulting in an amino acid change from phenylalanine to leucine at position 116. HLA-C*15:74 differs from HLA-C*15:08 by a nonsynonymous C to T substitution at nucleotide position 914 in exon 3, resulting in an amino acid change from arginine to tryptophan at position 156. © 2015 John Wiley & Sons Ltd.

Influence of Annealing on Microstructure and Mechanical Properties of Refractory CoCrMoNbTi0.4 High-Entropy Alloy

NASA Astrophysics Data System (ADS)

Zhang, Mina; Zhou, Xianglin; Zhu, Wuzhi; Li, Jinghao

2018-04-01

A novel refractory CoCrMoNbTi0.4 high-entropy alloy (HEA) was prepared via vacuum arc melting. After annealing treatment at different temperatures, the microstructure evolution, phase stability, and mechanical properties of the alloy were investigated. The alloy was composed of two primary body-centered cubic structures (BCC1 and BCC2) and a small amount of (Co, Cr)2Nb-type Laves phase under different annealing conditions. The microhardness and compressive strength of the heat-treated alloy was significantly enhanced by the solid-solution strengthening of the BCC phase matrix and newborn Laves phase. Especially, the alloy annealed at 1473 K (1200 °C) achieved the maximum hardness and compressive strength values of 959 ± 2 HV0.5 and 1790 MPa, respectively, owing to the enhanced volume fraction of the dispersed Laves phase. In particular, the HEAs exhibited promising high-temperature mechanical performance, when heated to an elevated temperature of 1473 K (1200 °C), with a compressive fracture strength higher than 580 MPa without fracture at a strain of more than 20 pct. This study suggests that the present refractory HEAs have immense potential for engineering applications as a new class of high-temperature structural materials.

Phase transition in a tetragonal In90Pb10 alloy under high pressure: a switch from c/a > 1 to c/a < 1

NASA Astrophysics Data System (ADS)

Degtyareva, V. F.; Bdikin, I. K.; Porsch, F.; Novokhatskaya, N. I.

2003-03-01

The effect of pressure on tetragonal In-Pb alloys with 10, 15, and 22 at.% Pb has been studied up to pressure 30 GPa with diamond anvil cells using synchrotron radiation. The In-type face-centred tetragonal phase of the In alloy with 10 at.% Pb undergoes under pressure a phase transition with a discontinuous jump of the axial ratio from c/a > 1 to c/a < 1 via a two-phase region from 7 to 20 GPa. The tetragonal phases of the In alloys with 15 and 22 at.% Pb with c/a < 1 at ambient pressure show only a slight decrease in c/a with pressure increase. The correlation of the axial ratio with the alloy content and its change with pressure in In alloys and In itself are attributed to Brillouin-zone-Fermi-sphere interactions.

Influence of Thermal Ageing on Microstructure and Tensile Properties of P92 Steel

NASA Astrophysics Data System (ADS)

Sakthivel, T.; Selvi, S. Panneer; Parameswaran, P.; Laha, K.

2018-04-01

Microstructure and tensile properties of P92 steel in the normalized and tempered, and thermal aged at 923 K for 5000 h and 10,000 h conditions have been investigated. Laves phase precipitate was observed in the thermal-aged steels. The size of Laves phase precipitate increased with increase in thermal exposure. This was also confirmed from the observation that the area fraction of Laves phase precipitate was higher in the 5000 h aged condition which decreased with further increase in thermal exposure. On the other hand, the size and area fraction of M23C6 precipitate were found increased in the 5000 h aged steel, further continued to enhanced precipitation of fine M23C6 in the 10,000 h aged steel. This resulted in significant increase in area fraction and comparable size with the steel aged for 5000 h. Hardness of the steel was decreased with increase in the duration of ageing. Thermal-aged steels exhibited lower yield stress, ultimate tensile strength and relatively higher ductility in comparison with steel in the normalized and tempered condition. The increase in lath width and recovery of dislocation structure under thermal-aged condition resulted in lower tensile strength and hardness. An extensive Laves phase formation and coarsening by loss of tungsten in the matrix led to decrease in the tensile strength predominantly in the 5000 h aged steel. The tensile strength of 10,000 h aged steel was comparable with that of 5000 h aged steel due to enhanced precipitation of fine M23C6 in the steel due to enhanced mobility of carbon in the absence of tungsten in the matrix.

The Effect of Nb Addition on the Microstructure and the High-Temperature Strength of Fe3Al Aluminide

NASA Astrophysics Data System (ADS)

Kratochvíl, Petr; Švec, Martin; Král, Robert; Veselý, Jozef; Lukáč, Pavel; Vlasák, Tomáš

2018-02-01

The microstructural and high-temperature mechanical properties of Fe-26Al-xNb (x = 3 and 5 at. pct) are compared. The alloys were investigated "as cast" and after hot rolling at 1473 K (1200 °C). Scanning electron microscopes equipped with EDS and EBSD were used for the microstructure and phase identification. The addition of 3 at. pct of Nb into the Fe3Al matrix leads to the formation of C14 λ—Laves phase (Fe,Al)2Nb (LP) particles spread in the Fe3Al matrix, while an eutectic with thin lamellae of LP C14 λ—Laves phase (Fe,Al)2Nb and matrix is also formed in the iron aluminide with 5 at. pct of Nb. The presence of incoherent precipitates is connected with the enhancement of the high-temperature strength and creep resistance.

High-pressure phases of cordierite from single-crystal X-ray diffraction to 15 GPa

DOE PAGES

Finkelstein, Gregory J.; Dera, Przemyslaw K.; Duffy, Thomas S.

2015-08-14

High-pressure single-crystal X-ray diffraction experiments were conducted on natural cordierite crystals with composition Mg1.907(18)Fe0.127(6)Al4.01(2)Si4.96(3)Na0.026(3)O18.12(9) using a synchrotron X-ray source. The samples were compressed at 300 K in a diamond anvil cell to a maximum pressure of 15.22(15) GPa with a neon pressure-transmitting medium and a gold pressure calibrant. We observed a recently described orthorhombic to triclinic transition, as well as a further transition to a second triclinic phase. We solved and refined both new triclinic hases in space group P1, and designate them cordierite II and III. The structures of cordierite II and III were refined at 7.52(3) GPa atmore » 15.22(15) GPa, respectively. The lattice parameters at these pressures are a = 15.567(3) Å, b = 9.6235(4) Å, c = 9.0658(6) Å, α = 89.963(5)°, β = 86.252(10)°, and γ = 90.974(8)° for cordierite II, and a = 8.5191(19) Å, b = 8.2448(3) Å, c = 9.1627(4) Å, α = 85.672(4)°, β = 85.986(7)°, and γ = 70.839(10)° for cordierite III. Across the phase transitions there is a significant reduction in the length of the a-axis (~2 Å per phase transition), whereas both the b- and c-axis remain largely unchanged. Cordierite II has four- and five-coordinated Si and Al, while cordierite III has four-, five-, and six-coordinated Si, four- and five-coordinated Al, and five- and six-coordinated Mg. The sequence of high-pressure phases shows increasing polymerization of coordination polyhedra. These results, together with other recent studies, suggest that mixed 4-, 5-, and 6-fold coordination states may occur more commonly in silicate structures compressed at 300 K than previously recognized.« less

Self-consistent full-potential linearized-augmented-plane-wave local-density electronic-structure studies of magnetism and superconductivity in C15 compounds: ZrZn/sub 2/ and ZrV/sub 2/

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, M.; Jansen, H.J.F.; Freeman, A.J.

The electronic structure and properties of the cubic Laves phase (C15) compounds ZrZn/sub 2/ and ZrV/sub 2/ have been determined using our all-electron full-potential linearized-augmented-plane-wave (FLAPW) method for bulk solids. The computations were performed in two stages: (i) self-consistent warped muffin tin and (ii) self-consistent full potential. Spin-orbit coupling was included after either stage. The effects of the inclusion of the nonspherical terms inside the muffin tins on the eigenvalues is found to be small (of order 1 mRy). However, due to the fact that some of the bands near the Fermi level are flat, this effect leads to amore » much higher value of the density of states at E/sub F/ in ZnZr/sub 2/. The most important difference between the materials ZrZn/sub 2/ and ZrV/sub 2/ is the position of the d bands derived from the Zr and V atoms. Consequently, these materials have completely different Fermi surfaces. We have investigated the magnetic properties of these compounds by evaluating their generalized Stoner factors and found agreement with experiment. Our results for the superconducting transition temperature for these materials is found to be strongly dependent on the spin fluctuation parameter ..mu../sub sp/. Of course, because of the magnetic transition, superconductivity cannot be observed in ZnZr/sub 2/.« less

C-Peptide Decline in Type 1 Diabetes Has Two Phases: An Initial Exponential Fall and a Subsequent Stable Phase.

PubMed

Shields, Beverley M; McDonald, Timothy J; Oram, Richard; Hill, Anita; Hudson, Michelle; Leete, Pia; Pearson, Ewan R; Richardson, Sarah J; Morgan, Noel G; Hattersley, Andrew T

2018-06-07

The decline in C-peptide in the 5 years after diagnosis of type 1 diabetes has been well studied, but little is known about the longer-term trajectory. We aimed to examine the association between log-transformed C-peptide levels and the duration of diabetes up to 40 years after diagnosis. We assessed the pattern of association between urinary C-peptide/creatinine ratio (UCPCR) and duration of diabetes in cross-sectional data from 1,549 individuals with type 1 diabetes using nonlinear regression approaches. Findings were replicated in longitudinal follow-up data for both UCPCR ( n = 161 individuals, 326 observations) and plasma C-peptide ( n = 93 individuals, 473 observations). We identified two clear phases of C-peptide decline: an initial exponential fall over 7 years (47% decrease/year [95% CI -51%, -43%]) followed by a stable period thereafter (+0.07%/year [-1.3, +1.5]). The two phases had similar durations and slopes in patients above and below the median age at diagnosis (10.8 years), although levels were lower in the younger patients irrespective of duration. Patterns were consistent in both longitudinal UCPCR ( n = 162; ≤7 years duration: -48%/year [-55%, -38%]; >7 years duration -0.1% [-4.1%, +3.9%]) and plasma C-peptide ( n = 93; >7 years duration only: -2.6% [-6.7%, +1.5%]). These data support two clear phases of C-peptide decline: an initial exponential fall over a 7-year period, followed by a prolonged stabilization where C-peptide levels no longer decline. Understanding the pathophysiological and immunological differences between these two phases will give crucial insights into understanding β-cell survival. © 2018 by the American Diabetes Association.

Effect of molybdenum additions on the microstructures and corrosion behaviours of 316L stainless steel-based alloys

DOE PAGES

Rahman, T.; Ebert, W. L.; Indacochea, J. E.

2018-02-28

Alloys were made by alloying 5, 10, 15, 17.5, and 20 wt % Mo with Type 316L stainless steel. Sigma phases containing 21–29 wt % Mo formed along the austenite grain boundaries with the addition of 5 wt % Mo and increased with additions up to 15 wt % Mo, but they decreased with further additions. Laves phases containing 33–40 wt % Mo co-precipitated at additions of 10 wt % Mo which increased with further Mo increases. The corrosion resistance, assessed by potentiodynamic polarisation in a 10 mM NaCl solution adjusted to pH 4, increased relative to Type 316L formore » alloys made with 5 and 10 wt % added Mo, but decreased with further additions due to preferential corrosion of the Laves phase. The alloy made with 10 wt % added Mo had the highest corrosion resistance due primarily to the high Mo content of the austenite.« less

Effect of molybdenum additions on the microstructures and corrosion behaviours of 316L stainless steel-based alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rahman, T.; Ebert, W. L.; Indacochea, J. E.

Alloys were made by alloying 5, 10, 15, 17.5, and 20 wt % Mo with Type 316L stainless steel. Sigma phases containing 21–29 wt % Mo formed along the austenite grain boundaries with the addition of 5 wt % Mo and increased with additions up to 15 wt % Mo, but they decreased with further additions. Laves phases containing 33–40 wt % Mo co-precipitated at additions of 10 wt % Mo which increased with further Mo increases. The corrosion resistance, assessed by potentiodynamic polarisation in a 10 mM NaCl solution adjusted to pH 4, increased relative to Type 316L formore » alloys made with 5 and 10 wt % added Mo, but decreased with further additions due to preferential corrosion of the Laves phase. The alloy made with 10 wt % added Mo had the highest corrosion resistance due primarily to the high Mo content of the austenite.« less

40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this section...

40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this section...

40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this section...

40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this section...

40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this section...

Changes in the proteome of Escherichia coli during growth at 15 degrees C after incubation at 2, 6 or 8 degrees C for 4 days.

PubMed

Jones, T H; Johns, M W; Gill, C O

2008-06-10

For better understanding of the complex behaviour of Escherichia coli at chiller temperatures, log phase E. coli grown at 15 degrees C were incubated at 8, 6, or 2 degrees C for 4 days, and were then incubated at 15 degrees C for 12 h. Cultures were sampled after incubation at the lower temperatures, and during subsequent incubation at 15 degrees C. Proteins extracted from the samples were separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Spots of 45 previously identified proteins that were differentially expressed at 15 or < or =8 degrees C were quantified by image analysis. After incubation at 8 or 6 degrees C for 4 days cells were growing with or without formation of elongated cells (filaments), respectively, but growth did not occur at 2 degrees C. In cells incubated at 8 or 6 degrees C proteins associated with the stress response and energy generation were upregulated and proteins associated with protein synthesis were downregulated, while protein levels in cells incubated at 2 degrees C were little changed. When cells were then incubated at 15 degrees C, the levels of differentially expressed proteins in cells that had been incubated at 8 or 6 degrees C decreased or increased towards the levels found in cells growing at 15 degrees C, but some proteins were still under or over expressed after 12 h. In cells incubated at 15 degrees C after incubation at 2 degrees C, the levels of many of the proteins declined but the levels of proteins associated with protein synthesis increased. The findings indicate that the physiological states of log phase E. coli incubated at < or =2 degrees C or at higher chiller temperature are different, but that for both states incubation at an above chiller temperature for >3 generations is required before protein levels adjusted to those usual for the higher temperature. Cells in these different physiological states may respond differently to other stresses encountered during warming of chilled foods.

Phase stability, swelling, microstructure and strength of Ti 3SiC 2-TiC ceramics after low dose neutron irradiation

DOE PAGES

Ang, Caen; Zinkle, Steven; Shih, Chunghao; ...

2016-10-22

In this study, M n+1AX n (MAX) phase Ti 3SiC 2 materials were neutron irradiated at ~400, ~630, and 700 °C to a fluence of ~2 × 10 25 n/m 2 (E > 0.1 MeV). After irradiation at ~400 °C, anisotropic c-axis dilation of ~1.5% was observed. Room temperature strength was reduced from 445 ± 29 MPa to 315 ± 33 MPa and the fracture surfaces showed flat facets and transgranular cracks instead of typical kink-band deformation and bridging ligaments. XRD phase analysis indicated an increase of 10–15 wt% TiC. After irradiation at ~700 °C there were no lattice parametermore » changes, ~5 wt% decomposition to TiC occurred, and strength was 391 ± 71 MPa and 378 ± 31 MPa. The fracture surfaces indicated kink-band based deformation but with lesser extent of delamination than as-received samples. Finally, Ti 3SiC 2 appears to be radiation tolerant at ~400 °C, and increasingly radiation resistant at ~630–700 °C, but a higher temperature may be necessary for full recovery.« less

Studies of Nucleation and Growth, Specific Heat and Viscosity of Undercooled Melts of Quasicrystal and Polytetrahedral-Phase Forming Alloys

NASA Technical Reports Server (NTRS)

Kelton, K. F.; Gangopadhyay, Anup K.; Lee, G. W.; Hyers, Robert W.; Rathz, T. J.; Robinson, Michael B.; Rogers, Jan R.

2003-01-01

From extensive ground based work on the phase diagram and undercooling studies of Ti-Zr-Ni alloys, have clearly identified the composition of three different phases with progressively increasing polytetrahedral order such as, (Ti/Zr), the C14 Laves phase, and the i-phase, that nucleate directly from the undercooled liquid. The reduced undercooling decreases progressively with increasing polytetrahedral order in the solid, supporting Frank s hypothesis. A new facility for direct measurements of the structures and phase transitions in undercooled liquids (BESL) was developed and has provided direct proof of the primary nucleation of a metastable icosahedral phase in some Ti-Zr-Ni alloys. The first measurements of specific heat and viscosity in the undercooled liquid of this alloy system have been completed. Other than the importance of thermo-physical properties for modeling nucleation and growth processes in these materials, these studies have also revealed some interesting new results (such as a maximum of C(sup q, sub p) in the undercooled state). These ground-based results have clearly established the necessary background and the need for conducting benchmark nucleation experiments at the ISS on this alloy system.

Phase Separation and Crystallization of Hemoglobin C in Transgenic Mouse and Human Erythrocytes

PubMed Central

Canterino, Joseph E.; Galkin, Oleg; Vekilov, Peter G.; Hirsch, Rhoda Elison

2008-01-01

Individuals expressing hemoglobin C (β6 Glu→Lys) present red blood cells (RBC) with intraerythrocytic crystals that form when hemoglobin (Hb) is oxygenated. Our earlier in vitro liquid-liquid (L-L) phase separation studies demonstrated that liganded HbC exhibits a stronger net intermolecular attraction with a longer range than liganded HbS or HbA, and that L-L phase separation preceded and enhanced crystallization. We now present evidence for the role of phase separation in HbC crystallization in the RBC, and the role of the RBC membrane as a nucleation center. RBC obtained from both human homozygous HbC patients and transgenic mice expressing only human HbC were studied by bright-field and differential interference contrast video-enhanced microscopy. RBC were exposed to hypertonic NaCl solution (1.5–3%) to induce crystallization within an appropriate experimental time frame. L-L phase separation occurred inside the RBC, which in turn enhanced the formation of intraerythrocytic crystals. RBC L-L phase separation and crystallization comply with the thermodynamic and kinetics laws established through in vitro studies of phase transformations. This is the first report, to the best of our knowledge, to capture a temporal view of intraerythrocytic HbC phase separation, crystal formation, and dissolution. PMID:18621841

Multiple Nonstoichiometric Phases with Discrete Composition Ranges in the CaAu5−CaAu4Bi−BiAu2 System. A Case Study of the Chemistry of Spinodal Decomposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Qisheng; Corbett, John D.

2010-04-01

Synthetic explorations in the CaAu{sub 5}-CaAu{sub 4}Bi-BiAu{sub 2} system at 400 C reveal five separate solid solution regions that show three distinct substitution patterns in the CaAu{sub 5} parent: (I) CaAu{sub 4}(Au{sub 1-m}Bi{sub m}) with 0 {le} m {le} 0.15(1), (II) 0.33(1) {le} m {le} 0.64(1), (III) 0.85(4) {le} m {le} 0.90(2); (IV) (Ca{sub 1-r}Au{sub r})Au{sub 4}(Bi{sub 1-s}Au{sub s}) with 0 {le} r {le} 0.39(1) and 0 {le} s {le} 0.12(2); (V) (Ca{sub 1-p-q}Au{sub p}Bi{sub q})Au{sub 4}Bi with 0.09(2) {le} p {le} 0.13(1) and 0.31(2) {le} q {le} 0.72(4). Single crystal X-ray studies establish that all of these phase regionsmore » have common cubic symmetry F{sub 4}3m and that their structures (MgCu{sub 4}Sn-type, an ordered derivative of MgCu{sub 2}) all feature three-dimensional networks of Au{sub 4} tetrahedra, in which the truncated tetrahedra are centered and capped by Ca/Au, Au/Bi, or Ca/Au/Bi mixtures to give 16-atom Friauf polyhedra. TB-LMTO-ASA and -COHP calculations also reveal that direct interactions between Ca-Au and Ca-Bi pairs of atoms are relatively weak and that the Bi-Au interactions in the unstable ideal CaAu{sub 4}Bi are antibonding in character at E{sub F} but that their bonding is optimized at {+-}1 e. Compositions between the five nonstoichiometric phases appear to undergo spinodal decompositions. The last phenomenon has been confirmed by HRTEM, STEM-HAADF, EPMA, and XRD studies of the nominal composition CaAu{sub 4.25}Bi{sub 0.75}. Its DTA analyses suggest that the phases resulting from spinodal decomposition have nearly the same melting point ({approx}807 C), as expected, and that they are interconvertible through peritectic reactions at {approx}717 C.« less

[Simultaneous determination of 15 industrial synthetic dyes in condiment by solid phase extraction-high performance liquid chromatography].

PubMed

Liu, Min; Li, Xiaolin; Bie, Wei; Wang, Minglin; Feng, Qian

2011-02-01

A new method was established for the determination of 15 industrial synthetic dyes in condiment by solid phase extraction-high performance liquid chromatography (SPE-HPLC). The samples were extracted by methanol-water (1:1, v/v) and purified by a solid phase extraction column. Then, the chromatographic separation was achieved on a Luna C18 column by linear gradient elution. The mobile phase was 10 mmol/L ammonium acetate-acetonitrile (containing 1% acetic acid). The results showed that the 15 industrial synthetic dyes can be separated efficiently. The recoveries of the 15 industrial synthetic dyes spiked in condiment were between 84.6% and 114.2% with the relative standard deviations of 0.9% - 10.3%. The limits of detection of this method was 0.05 - 0.18 mg/kg for the 15 industrial synthetic dyes. The method is simple, sensitive, accurate, repeatable and can be used for simultaneous determination of the 15 illegally added industrial synthetic dyes.

Microstructural evolution of neutron-irradiated T91 and NF616 to ~4.3 dpa at 469 °C

DOE PAGES

Tan, Lizhen; Kim, B. K.; Yang, Ying; ...

2017-05-30

Ferritic-martensitic steels such as T91 and NF616 are candidate materials for several nuclear applications. Here, this study evaluates radiation resistance of T91 and NF616 by examining their microstructural evolutions and hardening after the samples were irradiated in the Advanced Test Reactor to ~4.3 displacements per atom (dpa) at an as-run temperature of 469 °C. In general, this irradiation did not result in significant difference in the radiation-induced microstructures between the two steels. Compared to NF616, T91 had a higher number density of dislocation loops and a lower level of radiation-induced segregation, together with a slightly higher radiation-hardening. Unlike dislocation loopsmore » developed in both steels, radiation-induced cavities were only observed in T91 but remained small with sub-10 nm sizes. Lastly, other than the relatively stable M 23C 6, a new phase (likely Sigma phase) was observed in T91 and radiation-enhanced MX → Z phase transformation was identified in NF616. Laves phase was not observed in the samples.« less

Stellar Origins of C-13 and N-15-Enriched Presolar SiC Grains

NASA Technical Reports Server (NTRS)

Liu, Nan; Nittler, Larry R.; Alexander, Conel M. O’D.; Wang, Jianhua; Pignatari, Marco; Jose, Jordi; Nguyen, Ann

2016-01-01

Extreme excesses of 13 C ( C (12 C/ 13 C<10) and 15 N ( N (14 N/ 15 N< 20) in rare presolar SiC 20) in rare presolar SiClar SiC grains have been considered diagnostic of an origin in classical novae [1], though an origin in core-collapse supernovae (CCSNe) has also been proposed [2]. We report multi-element isotopic data for 19 13 C- and 15 N-enriched presolar SiC grains(12 C/13 C<16 and 14 N/ 15 N<150) from an acid resistant residue of the Murchison meteorite. These grains are enriched in 13 C and15 N, but with quite diverse Si isotopic signatures. Four grains with isotopic signatures. Four grains with isotopic signatures. Four grains with isotopic signatures. Four grains with isotopic signatures.

Magnéli phases Ti{sub 4}O{sub 7} and Ti{sub 8}O{sub 15} and their carbon nanocomposites via the thermal decomposition-precursor route

DOE Office of Scientific and Technical Information (OSTI.GOV)

Conze, S., E-mail: susan.conze@ikts.fraunhofer.de; Veremchuk, I.; Reibold, M.

2015-09-15

A new synthetic approach for producing nano-powders of the Magnéli phases Ti{sub 4}O{sub 7}, Ti{sub 8}O{sub 15} and their carbon nanocomposites by thermal decomposition-precursor route is proposed. The formation mechanism of the single-phase carbon nanocomposites (Ti{sub 4}O{sub 7}/C and Ti{sub 8}O{sub 15}/C) from metal–organic precursors is studied using FT-IR, elemental analysis, TG, STA-MS and others. The synthesis parameters and conditions were optimized to prepare the target oxides with the desired microstructure and physical properties. The electrical and transport properties of Ti{sub 4}O{sub 7}/C and Ti{sub 8}O{sub 15}/C are investigated. These nano-materials are n-type semiconductors with relatively low thermal conductivity inmore » contrast to the bulk species. The nanostructured carbon nanocomposites of Magnéli phases achieve a low thermal conductivity close to 1 W/m K at RT. The maximum ZT{sub 570} {sub °C} values are 0.04 for Ti{sub 4}O{sub 7}/C powder nanocomposite and 0.01 for Ti{sub 8}O{sub 15}/C bulk nanocomposite. - Graphical abstract: From the precursor to the produced titanium oxide pellet and its microstructure (SEM, TEM micrographs) as well as results of phase and thermoelectric analyses. - Highlights: • Magnéli phases Ti{sub 4}O{sub 7}/Ti{sub 8}O{sub 15} via thermal decomposition-precursor route is proposed. • The formation mechanism of the nanocomposites Ti{sub 4}O{sub 7}/C and Ti{sub 8}O{sub 15}/C are investigated. • Microstructure of Ti{sub 4}O{sub 7}/C and Ti{sub 8}O{sub 15}/C are examined. • The electrical and transport properties of Ti{sub 4}O{sub 7}/C and Ti{sub 8}O{sub 15}/C are investigated. • The maximum figure of mertit ZT{sub 570} {sub °C} of Ti{sub 4}O{sub 7}/C and Ti{sub 8}O{sub 15}/C are 0.01 and 0.04.« less

Synthesis and Study on Ionic Conductive (Bi1−x,Vx)O1.5−δ Materials with a Dual-Phase Microstructure

PubMed Central

Lai, Yu-Wei; Wei, Wen-Cheng J.

2016-01-01

Homogeneous Bi2O3-V2O5 powder mixtures with different amounts of V2O5 content (≤15 mol%) were prepared by colloidal dispersion and sintering to high density. The sintered and annealed samples were studied by thermal analysis, quantitative X-ray diffraction and scanning electron microscopy. The electrical and ionic conductivities of the conductors were also measured by a four-probe direct current (DC) method. The results of the samples prepared at 600–800 °C and annealed for as long as 100 h show that the sintered samples consisting of a pure γ phase or δ + γ binary phase perform differently in conductivity. The highly conductive δ phase in the composition of Bi0.92V0.08O1.5−δ enhances the electric conductivity 10-times better than that of the pure γ-sample (Bi0.94V0.06O1.5−δ) between 400 and 600 °C. The compatible regions of the γ phase with the α- or δ phase are also reported and discussed, so a part of the previously published Bi2O3-V2O5 phase diagram below 800 °C is revised. PMID:28773981

Thermal processing of diblock copolymer melts mimics metallurgy

NASA Astrophysics Data System (ADS)

Kim, Kyungtae; Schulze, Morgan W.; Arora, Akash; Lewis, Ronald M.; Hillmyer, Marc A.; Dorfman, Kevin D.; Bates, Frank S.

2017-05-01

Small-angle x-ray scattering experiments conducted with compositionally asymmetric low molar mass poly(isoprene)-b-poly(lactide) diblock copolymers reveal an extraordinary thermal history dependence. The development of distinct periodic crystalline or aperiodic quasicrystalline states depends on how specimens are cooled from the disordered state to temperatures below the order-disorder transition temperature. Whereas direct cooling leads to the formation of documented morphologies, rapidly quenched samples that are then heated from low temperature form the hexagonal C14 and cubic C15 Laves phases commonly found in metal alloys. Self-consistent mean-field theory calculations show that these, and other associated Frank-Kasper phases, have nearly degenerate free energies, suggesting that processing history drives the material into long-lived metastable states defined by self-assembled particles with discrete populations of volumes and polyhedral shapes.

Cumulative carbon emissions budgets consistent with 1.5 °C global warming

NASA Astrophysics Data System (ADS)

Tokarska, Katarzyna B.; Gillett, Nathan P.

2018-04-01

The Paris Agreement1 commits ratifying parties to pursue efforts to limit the global temperature increase to 1.5 °C relative to pre-industrial levels. Carbon budgets2-5 consistent with remaining below 1.5 °C warming, reported in the IPCC Fifth Assessment Report (AR5)2,6,8, are directly based on Earth system model (Coupled Model Intercomparison Project Phase 5)7 responses, which, on average, warm more than observations in response to historical CO2 emissions and other forcings8,9. These models indicate a median remaining budget of 55 PgC (ref. 10, base period: year 1870) left to emit from January 2016, the equivalent to approximately five years of emissions at the 2015 rate11,12. Here we calculate warming and carbon budgets relative to the decade 2006-2015, which eliminates model-observation differences in the climate-carbon response over the historical period9, and increases the median remaining carbon budget to 208 PgC (33-66% range of 130-255 PgC) from January 2016 (with mean warming of 0.89 °C for 2006-2015 relative to 1861-188013-18). There is little sensitivity to the observational data set used to infer warming that has occurred, and no significant dependence on the choice of emissions scenario. Thus, although limiting median projected global warming to below 1.5 °C is undoubtedly challenging19-21, our results indicate it is not impossible, as might be inferred from the IPCC AR5 carbon budgets2,8.

42 CFR 68c.15 - Additional conditions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Additional conditions. 68c.15 Section 68c.15 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTE OF CHILD HEALTH AND HUMAN DEVELOPMENT CONTRACEPTION AND INFERTILITY RESEARCH LOAN...

42 CFR 68c.15 - Additional conditions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Additional conditions. 68c.15 Section 68c.15 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTE OF CHILD HEALTH AND HUMAN DEVELOPMENT CONTRACEPTION AND INFERTILITY RESEARCH LOAN...

42 CFR 68c.15 - Additional conditions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Additional conditions. 68c.15 Section 68c.15 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTE OF CHILD HEALTH AND HUMAN DEVELOPMENT CONTRACEPTION AND INFERTILITY RESEARCH LOAN...

15N and13C NMR investigation of hydroxylamine-derivatized humic substances

USGS Publications Warehouse

Thorn, K.A.; Arterburn, J.B.; Mikita, M.A.

1992-01-01

Five fulvic and humic acid samples of diverse origins were derivatized with 15N-labeled hydroxylamine and analyzed by liquid-phase 15N NMR spectrometry. The 15N NMR spectra indicated that hydroxylamine reacted similarly with all samples and could discriminate among carbonyl functional groups. Oximes were the major derivatives; resonances attributable to hydroxamic acids, the reaction products of hydroxylamine with esters, and resonances attributable to the tautomeric equilibrium position between the nitrosophenol and monoxime derivatives of quinones, the first direct spectroscopic evidence for quinones, also were evident. The 15N NMR spectra also suggested the presence of nitriles, oxazoles, oxazolines, isocyanides, amides, and lactams, which may all be explained in terms of Beckmann reactions of the initial oxime derivatives. INEPT and ACOUSTIC 15N NMR spectra provided complementary information on the derivatized samples. 13C NMR spectra of derivatized samples indicated that the ketone/quinone functionality is incompletely derivatized with hydroxylamine. ?? 1991 American Chemical Society.

Consequences of 1.5 °C and 2 °C global warming levels for temperature and precipitation changes over Central Africa

NASA Astrophysics Data System (ADS)

Pokam Mba, Wilfried; Longandjo, Georges-Noel T.; Moufouma-Okia, Wilfran; Bell, Jean-Pierre; James, Rachel; Vondou, Derbetini A.; Haensler, Andreas; Fotso-Nguemo, Thierry C.; Merlin Guenang, Guy; Djiotang Tchotchou, Angennes Lucie; Kamsu-Tamo, Pierre H.; Takong, Ridick R.; Nikulin, Grigory; Lennard, Christopher J.; Dosio, Alessandro

2018-05-01

Discriminating climate impacts between 1.5 °C and 2 °C warming levels is particularly important for Central Africa, a vulnerable region where multiple biophysical, political, and socioeconomic stresses interact to constrain the region’s adaptive capacity. This study uses an ensemble of 25 transient Regional Climate Model (RCM) simulations from the CORDEX initiative, forced with the Representative Concentration Pathway (RCP) 8.5, to investigate the potential temperature and precipitation changes in Central Africa corresponding to 1.5 °C and 2 °C global warming levels. Global climate model simulations from the Coupled Model Intercomparison Project phase 5 (CMIP5) are used to drive the RCMs and determine timing of the targeted global warming levels. The regional warming differs over Central Africa between 1.5 °C and 2 °C global warming levels. Whilst there are large uncertainties associated with projections at 1.5 °C and 2 °C, the 0.5 °C increase in global temperature is associated with larger regional warming response. Compared to changes in temperature, changes in precipitation are more heterogeneous and climate model simulations indicate a lack of consensus across the region, though there is a tendency towards decreasing seasonal precipitation in March–May, and a reduction of consecutive wet days. As a drought indicator, a significant increase in consecutive dry days was found. Consistent changes of maximum 5 day rainfall are also detected between 1.5 °C vs. 2 °C global warming levels.

Phase Transition Enthalpy Measurements of Organic and Organometallic Compounds. Sublimation, Vaporization and Fusion Enthalpies From 1880 to 2015. Part 1. C1 - C10

NASA Astrophysics Data System (ADS)

Acree, William; Chickos, James S.

2016-09-01

A compendium of phase change enthalpies published in 2010 is updated to include the period 1880-2015. Phase change enthalpies including fusion, vaporization, and sublimation enthalpies are included for organic, organometallic, and a few inorganic compounds. Part 1 of this compendium includes organic compounds from C1 to C10. Part 2 of this compendium, to be published separately, will include organic and organometallic compounds from C11 to C192. Sufficient data are presently available to permit thermodynamic cycles to be constructed as an independent means of evaluating the reliability of the data. Temperature adjustments of phase change enthalpies from the temperature of measurement to the standard reference temperature, T = 298.15 K, and a protocol for doing so are briefly discussed.

Comparison of halo of 11Be, 15C, and 19C

NASA Astrophysics Data System (ADS)

Kharab, R.; Kumar, R.; Singh, P.; Sharma, H. C.

2007-12-01

We have compared the halo of 11Be, 15C, and 19C nuclei by analyzing the one-neutron stripping reaction data on the Be target at 60-, 54-, and 57-MeV/ A beam energies, respectively, within the framework of the eikonal approximation approach. The determination of effective range through the comparison of the total cross section data and prediction has revealed that the halo of 19C is the well developed, while that of 15C is the least and that of 11Be lies in between these two. The longitudinal momentum distribution data also strengthen these observations.

15 CFR 8c.60 - Communications.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Communications. 8c.60 Section 8c.60 Commerce and Foreign Trade Office of the Secretary of Commerce ENFORCEMENT OF NONDISCRIMINATION ON THE BASIS OF HANDICAP IN PROGRAMS OR ACTIVITIES CONDUCTED BY THE DEPARTMENT OF COMMERCE § 8c.60...

Speciation in the Fe(III)-Cl(I)-H2O System at 298.15 K, 313.15 K, and 333.15 K (25 °C, 40 °C, and 60 °C)

NASA Astrophysics Data System (ADS)

Jamett, Nathalie E.; Hernández, Pía C.; Casas, Jesús M.; Taboada, María E.

2018-02-01

This article presents the results on speciation of ferric iron generated by the dissolution of chemical reagent hydromolysite (ferric chloride hexahydrate, FeCl3:6H2O) in water at 298.15 K, 313.15 K, and 333.15 K (25 °C, 40 °C, and 60 °C). Experiments were performed with a thermoregulated system up to the equilibrium point, as manifested by solution pH. Solution samples were analyzed in terms of concentration, pH, and electrical conductivity. Measurements of density and refractive index were obtained at different temperatures and iron concentrations. A decrease of pH was observed with the increase in the amount of dissolved iron, indicating that ferric chloride is a strong electrolyte that reacts readily with water. Experimental results were modeled using the hydrogeochemical code PHREEQC in order to obtain solution speciation. Cations and neutral and anion complexes were simultaneously present in the system at the studied conditions according to model simulations, where dominant species included Cl-, FeCl2+, FeCl2 +, FeOHCl 2 0 , and H+. A decrease in the concentration of Cl- and Fe3+ ions took place with increasing temperature due to the association of Fe-Cl species. Standard equilibrium constants for the formation of FeOHCl 2 0 obtained in this study were log Kf0 = -0.8 ± 0.01 at 298.15 K (25 °C), -0.94 ± 0.02 at 313.15 K (40 °C), and -1.03 ± 0.01 at 333.15 K (60 °C).

15 CFR 8c.40 - Employment.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Employment. 8c.40 Section 8c.40... BASIS OF HANDICAP IN PROGRAMS OR ACTIVITIES CONDUCTED BY THE DEPARTMENT OF COMMERCE § 8c.40 Employment... discrimination in employment under any program or activity conducted by the agency. The definitions, requirements...

An assessment of the retention behaviour of polycyclic aromatic hydrocarbons on reversed phase stationary phases: selectivity and retention on C18 and phenyl-type surfaces.

PubMed

Kayillo, Sindy; Dennis, Gary R; Shalliker, R Andrew

2006-09-08

In this manuscript the retention and selectivity of a set of linear and non-linear PAHs were evaluated on five different reversed-phase columns. These phases included C18 and C18 Aqua stationary phases, as well as three phenyl phases: Propyl-phenyl, Synergi polar-RP and Cosmosil 5PBB phase. Overall, the results revealed that the phenyl-type columns offered better separation performance for the linear PAHs, while the separation of the structural isomer PAHs was enhanced on the C18 columns. The Propyl-phenyl column was found to have the highest molecular-stationary phase interactions, as evidenced by the greatest rate of change in 'S' (0.71) as a function of the molecular weight in the PAH homologous series, despite having the lowest surface coverage (3% carbon load) (where S is the slope of a plot of logk versus the solvent composition). In contrast, the C18 Aqua column, having the highest surface coverage (15% carbon load) was found to have the second lowest molecular-stationary phase interactions (rate of change in S=0.61). Interestingly, the Synergi polar-RP column, which also is a phenyl stationary phase behaved more 'C18-like' than 'phenyl-like' in many of the tests undertaken. This is probably not unexpected since all five phases were reversed phase.

Application of C30B15N15 heterofullerene in the isoniazid drug delivery: DFT studies

NASA Astrophysics Data System (ADS)

Hazrati, Mehrnoosh Khodam; Bagheri, Zargham; Bodaghi, Ali

2017-05-01

Using density functional theory, we have investigated the potential application of a C30B15N15 heterofullerene in anti-cancer isoniazid drug delivery. It was found that isoniazid prefers to attach via its -NH2 group to a boron atom of the C30B15N15 with releasing a large energy of about 21.91 kcal/mol. Our partial density of states analysis demonstrates that the boron atoms significantly contribute in generation of virtual orbitals of C30B15N15 fullerene, indicating that these atoms will be suitable for nucleophilic attack rather than carbon atoms. In addition to the large released energy, the electronic properties C30B15N15 are significantly sensitive to the isoniazid attachment which can recognize the drug trajectory by affecting the fluorescence emission properties. Unlike, different nanostructures whose structures need to be manipulated to be suitable for drug delivery, the C30B15N15 fullerene can be used in the pristine form. We proposed a drug release mechanism in cancer tissues, representing that in the low pH of the cancer cells the drug and C30B15N15 fullerene are considerably protonated, thereby separating the drug from the surface of the fullerene. The reaction mechanism of the drug with the fullerene is changed from covalence in natural environment to hydrogen bonding in acidic cancer cells.

Mechanical Properties and Microstructural Characterization of Aged Nickel-based Alloy 625 Weld Metal

NASA Astrophysics Data System (ADS)

Silva, Cleiton Carvalho; de Albuquerque, Victor Hugo C.; Miná, Emerson Mendonça; Moura, Elineudo P.; Tavares, João Manuel R. S.

2018-03-01

The aim of this work was to evaluate the different phases formed during solidification and after thermal aging of the as-welded 625 nickel-based alloy, as well as the influence of microstructural changes on the mechanical properties. The experiments addressed aging temperatures of 650 and 950 °C for 10, 100, and 200 hours. The samples were analyzed by electron microscopy, microanalysis, and X-ray diffraction in order to identify the secondary phases. Mechanical tests such as hardness, microhardness, and Charpy-V impact test were performed. Nondestructive ultrasonic inspection was also conducted to correlate the acquired signals with mechanical and microstructural properties. The results show that the alloy under study experienced microstructural changes when aged at 650 °C. The aging was responsible by the dissolution of the Laves phase formed during the solidification and the appearance of γ″ phase within interdendritic region and fine carbides along the solidification grain boundaries. However, when it was aged at 950 °C, the Laves phase was continuously dissolved and the excess Nb caused the precipitation of the δ-phase (Ni3Nb), which was intensified at 10 hours of aging, with subsequent dissolution for longer periods such as 200 hours. Even when subjected to significant microstructural changes, the mechanical properties, especially toughness, were not sensitive to the dissolution and/or precipitation of the secondary phases.

A novel method to measure isotopic labeled gas-phase nitrous acid (HO15NO) in biogeochemical studies

NASA Astrophysics Data System (ADS)

Wu, Dianming; Kampf, Christopher; Pöschl, Ulrich; Oswald, Robert; Cui, Junfang; Ermel, Michael; Hu, Chunsheng; Trebs, Ivonne; Sörgel, Matthias

2014-05-01

We developed a new method (gas-phase stripping-derivatization coupled to LC-MS) to measure the 15N atom percent excess (APE) of HONO in the gas-phase. Gaseous HONO is quantitatively collected and transferred to an azo dye by the well-known Griess reaction in the Long Path Absorption Photometer (LOPAP). The reaction solutions containing the dye are collected at the outflow of the LOPAP, purified by solid-phase extraction and analyzed using high performance liquid chromatography coupled to mass spectrometry (HPLC-MS). The unlabeled azo dye (C18H19O2N5S) with a monoisotopic molecular mass of 369.41 g mol-1 can be detected as its protonated molecular ion ([M+H+], M) by HPLC-MS at a retention time of 2.8 min. Due to the natural isotope distribution M + 0, M + 1, M + 2, and M + 3 ions were considered for the calculation of the 15N APE. The optimal working range was found to be between 20 and 50% for the 15N/14N ratio. The optimum pH and solvents for extraction by SPE and potential interferences are discussed. The method has been applied for the measurement of HO15NO emissions from soil in a dynamic chamber with and without spiking 15N labeled urea. Our results confirm biogenic HONO emissions from soil as HO15NO was measured after addition of 15N urea.

Hydridable material for the negative electrode in a nickel-metal hydride storage battery

DOEpatents

Knosp, Bernard; Bouet, Jacques; Jordy, Christian; Mimoun, Michel; Gicquel, Daniel

1997-01-01

A monophase hydridable material for the negative electrode of a nickel-metal hydride storage battery with a "Lave's phase" structure of hexagonal C14 type (MgZn.sub.2) has the general formula: Zr.sub.1-x Ti.sub.x Ni.sub.a Mn.sub.b Al.sub.c Co.sub.d V.sub.e where ##EQU1##

15 CFR 8c.60 - Communications.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 15 Commerce and Foreign Trade 1 2011-01-01 2011-01-01 false Communications. 8c.60 Section 8c.60 Commerce and Foreign Trade Office of the Secretary of Commerce ENFORCEMENT OF NONDISCRIMINATION ON THE... Communications. (a) The agency shall take appropriate steps to ensure effective communication with applicants...

15 CFR 8c.60 - Communications.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 15 Commerce and Foreign Trade 1 2013-01-01 2013-01-01 false Communications. 8c.60 Section 8c.60 Commerce and Foreign Trade Office of the Secretary of Commerce ENFORCEMENT OF NONDISCRIMINATION ON THE... Communications. (a) The agency shall take appropriate steps to ensure effective communication with applicants...

On the differences between 1.5oC and 2oC of global warming

NASA Astrophysics Data System (ADS)

King, A.

2017-12-01

The Paris Agreement of 2015 has resulted in a drive to limit global warming to 2oC with an aim for a lower 1.5oC target. It is therefore vital that we understand some of the differences we would expect between these two levels of global warming. My research uses coupled climate model projections to investigate where and for what variables we can differentiate between worlds of 1.5oC and 2oC global warming. I place a particular focus on climate extremes and population exposure to those extremes. I have found that there are perceptible benefits in limiting global warming to 1.5oC as opposed to 2oC through reduced frequency and intensity of heat extremes, both over land and in ocean areas where thermal stress on coral has resulted in bleaching. Differences in high and low precipitation extremes between the 1.5oC and 2oC global warming levels are projected for some regions. I have also examined how "scalable" changes from the 1.5oC to 2oC level are. In areas of the world such as Eastern China I find that changes in anthropogenic aerosol concentrations will influence the level of change projected at 1.5oC and 2oC, such that past warming is likely to be a poor indicator of future changes. Overall, my research finds clear benefits to limiting global warming to 1.5oC relative to higher levels.

Determination of pterins in urine by HPLC with UV and fluorescent detection using different types of chromatographic stationary phases (HILIC, RP C8, RP C18).

PubMed

Kośliński, Piotr; Jarzemski, Piotr; Markuszewski, Michał J; Kaliszan, Roman

2014-03-01

Pterins are a class of potential cancer biomarkers. New methods involving hydrophilic interaction liquid chromatography (HILIC) and reversed phase (RP) high-performance liquid chromatography have been developed for analysis of eight pterin compounds: 6,7-dimethylpterin, pterin, 6-OH-methylpterin, biopterin, isoxanthopterin, neopterin, xanthopterin, and pterin-6-carboxylic acid. The effect of mobile phase composition, buffer type, pH and concentration on retention using HILIC, C8 and C18 RP stationary phases were examined. Separation of pterins on RP and HILIC stationary phase was performed and optimized. Eight pterins were successfully separated on HILIC Luna diol-bonded phases, Aquasil C18 RP column and LiChrospher C8 RP column. Determination and separation of the pterins from urine samples were performed on HILIC Luna and LiChrospher C8 RP columns which were chosen as the most appropriate ones. Finally, LiChrospher C8 RP column with fluorescence detection was selected for further validation of the method. The optimum chromatographic condition was mobile phase methanol (A)/phosphoric buffer pH 7, 10mM (B), isocratic elution 0-15min 5% A flow=0.5ml/min 15-17min. 5% A, flow=0.5-1ml/min the linearity (R(2)>0.997) and retention time repeatability (RSD%<1) were at satisfactory level. The precision of peak areas expressed as RSD in % was between 0.55 and 14. Pterins detection limits varied from 0.041ng/ml to 2.9ng/ml. Finally, HPLC method was used for the analysis of pterins in urine samples with two different oxidation procedures. Concentration levels of pterin compounds in bladder cancer patients and healthy subjects were compared. Copyright © 2013 Elsevier B.V. All rights reserved.

The effects of cold work on the microstructure and mechanical properties of intermetallic strengthened alumina-forming austenitic stainless steels

DOE PAGES

Hu, Bin; Baker, Ian; Miller, Michael K.; ...

2015-06-12

In order to achieve energy conversion efficiencies of >50 pct for steam turbines/boilers in power generation systems, materials are required that are both strong and corrosion-resistant at >973 K (700 °C), and economically viable. Austenitic steels strengthened with Laves phase, NiAl and Ni 3Al precipitates, and alloyed with aluminum to improve oxidation resistance, are potential candidate materials for these applications. The microstructure and microchemistry of recently developed alumina-forming austenitic stainless steels have been characterized by scanning electron microscopy, transmission electron microscopy, and synchrotron X-ray diffraction. Different thermo-mechanical treatments were performed on these steels to improve their mechanical performance. These reducedmore » the grain size significantly to the nanoscale (~100 nm) and the room temperature yield strength to above 1000 MPa. Lastly, a solutionizing anneal at 1473 K (1200 °C) was found to be effective for uniformly redistributing the Laves phase precipitates that form upon casting.« less

Powder Metallurgy Processing of a WxTaTiVCr High-Entropy Alloy and Its Derivative Alloys for Fusion Material Applications.

PubMed

Waseem, Owais Ahmed; Ryu, Ho Jin

2017-05-16

The W x TaTiVCr high-entropy alloy with 32at.% of tungsten (W) and its derivative alloys with 42 to 90at.% of W with in-situ TiC were prepared via the mixing of elemental W, Ta, Ti, V and Cr powders followed by spark plasma sintering for the development of reduced-activation alloys for fusion plasma-facing materials. Characterization of the sintered samples revealed a BCC lattice and a multi-phase structure. The selected-area diffraction patterns confirmed the formation of TiC in the high-entropy alloy and its derivative alloys. It revealed the development of C15 (cubic) Laves phases as well in alloys with 71 to 90at.% W. A mechanical examination of the samples revealed a more than twofold improvement in the hardness and strength due to solid-solution strengthening and dispersion strengthening. This study explored the potential of powder metallurgy processing for the fabrication of a high-entropy alloy and other derived compositions with enhanced hardness and strength.

Continued increase of extreme El Niño frequency long after 1.5 °C warming stabilization

NASA Astrophysics Data System (ADS)

Wang, Guojian; Cai, Wenju; Gan, Bolan; Wu, Lixin; Santoso, Agus; Lin, Xiaopei; Chen, Zhaohui; McPhaden, Michael J.

2017-08-01

The Paris Agreement aims to constrain global mean temperature (GMT) increases to 2 °C above pre-industrial levels, with an aspirational target of 1.5 °C. However, the pathway to these targets and the impacts of a 1.5 °C and 2 °C warming on extreme El Niño and La Niña events--which severely influence weather patterns, agriculture, ecosystems, public health and economies--is little known. Here, by analysing climate models participating in the Climate Model Intercomparison Project's Phase 5 (CMIP5; ref. ) under a most likely emission scenario, we demonstrate that extreme El Niño frequency increases linearly with the GMT towards a doubling at 1.5 °C warming. This increasing frequency of extreme El Niño events continues for up to a century after GMT has stabilized, underpinned by an oceanic thermocline deepening that sustains faster warming in the eastern equatorial Pacific than the off-equatorial region. Ultimately, this implies a higher risk of extreme El Niño to future generations after GMT rise has halted. On the other hand, whereas previous research suggests extreme La Niña events may double in frequency under the 4.5 °C warming scenario, the results presented here indicate little to no change under 1.5 °C or 2 °C warming.

The Effects of Cold Work on the Microstructure and Mechanical Properties of Intermetallic Strengthened Alumina-Forming Austenitic Stainless Steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, B.; Trotter, G.; Baker, Ian

2015-08-01

In order to achieve energy conversion efficiencies of > 50 pct for steam turbines/boilers in power generation systems, materials are required that are both strong and corrosion-resistant at > 973 K (700 A degrees C), and economically viable. Austenitic steels strengthened with Laves phase, NiAl and Ni3Al precipitates, and alloyed with aluminum to improve oxidation resistance, are potential candidate materials for these applications. The microstructure and microchemistry of recently developed alumina-forming austenitic stainless steels have been characterized by scanning electron microscopy, transmission electron microscopy, and synchrotron X-ray diffraction. Different thermo-mechanical treatments were performed on these steels to improve their mechanicalmore » performance. These reduced the grain size significantly to the nanoscale (similar to 100 nm) and the room temperature yield strength to above 1000 MPa. A solutionizing anneal at 1473 K (1200 A degrees C) was found to be effective for uniformly redistributing the Laves phase precipitates that form upon casting. (C) The Minerals, Metals & Materials Society and ASM International 2015« less

1,5-anhydroglucitol is associated with early-phase insulin secretion in chinese patients with newly diagnosed type 2 diabetes mellitus.

PubMed

Ma, Xiaojing; Hao, Yaping; Hu, Xiang; Luo, Yuqi; Deng, Zixuan; Zhou, Jian; Bao, Yuqian; Jia, Weiping

2015-05-01

The goal of the present study was to explore the correlations of 1,5-anhydroglucitol (l,5-AG), glycated hemoglobin (HbA1c), and glycated albumin (GA) with insulin sensitivity and secretion. In total, 302 patients with newly diagnosed type 2 diabetes mellitus (166 men, 136 women) were enrolled in this study. The homeostasis model assessment for insulin resistance (HOMA-IR) and homeostasis model assessment for β-cell function (HOMA-β) were calculated to determine the basal insulin sensitivity and secretion. The insulinogenic index (IGI) was used to evaluate early-phase insulin secretion. 1,5-AG and GA were assayed via the enzymatic method, and HbA1c was detected by high-pressure liquid chromatography. Among all 302 subjects, the serum 1,5-AG level was 13.1±7.2 μg/mL, and the HbA1c and GA levels [median (interquartile range)] were 6.7% (6.2-7.3%) and 17.7% (16.0-19.5%), respectively. Increased 1,5-AG quartiles were accompanied by trends toward a decreased HOMA-IR and an increased HOMA-β and IGI (for all trends, P<0.001). 1,5-AG was negatively associated with HOMA-IR (r=-0.200, P<0.001) and positively associated with HOMA-β and IGI (r=0.210 and 0.413, respectively; both P<0.001). 1,5-AG was independently related to HOMA-IR and HOMA-β and exhibited an independent positive association with IGI (standardized β=0.242, P<0.001). Additionally, both HbA1c and GA were independently correlated with HOMA-IR and HOMA-β. 1,5-AG is not only correlated with basal insulin sensitivity and secretion, but also closely associated with early-phase insulin secretion in Chinese patients with newly diagnosed type 2 diabetes mellitus.

15 CFR 8c.10 - Self-evaluation.

Code of Federal Regulations, 2014 CFR

2014-01-01

... handicaps or organizations representing individuals with handicaps, to participate in the self-evaluation... 15 Commerce and Foreign Trade 1 2014-01-01 2014-01-01 false Self-evaluation. 8c.10 Section 8c.10... BASIS OF HANDICAP IN PROGRAMS OR ACTIVITIES CONDUCTED BY THE DEPARTMENT OF COMMERCE § 8c.10 Self...

Microstructural changes in steel 10Kh9V2MFBR during creep for 40000 hours at 600°C

NASA Astrophysics Data System (ADS)

Fedoseeva, A. E.; Kozlov, P. A.; Dudko, V. A.; Skorobogatykh, V. N.; Shchenkova, I. A.; Kaibyshev, R. O.

2015-10-01

In this work, we have investigated microstructural changes in steel 10Kh9V2MFBR (analog of P02 steel) after long-term creep tests at a temperature of 600°C under an initial stress of 137 MPa. Time to rupture was found to be more than 40000 h. It has been established that, in the zone of grips and in the neck region of the sample, the size of the particles of the M 23C6 carbides increases from 85 nm to 152 nm and 182 nm, respectively. In addition, large particles of the Laves phase with an average size of 295 nm are separated. The particles of these phases are located along high-angle boundaries. During prolonged aging and creep, the transformation of the M(C,N) particles enriched in V into the Z phase occurs. The average size of particles of the Z phase after prolonged ageing was 48 nm; after creep, it reached 97 nm. The size of M(C,N) particles enriched by Nb increases from 26 nm after tempering to 55 nm after prolonged aging and creep. It has been established that, in spite of an increase in the transverse size of the laths of tempered martensite from 0.4 to 0.9 µm in the neck of the sample, the misorientation of the lath boundaries does not increase. No recrystallization processes were found to develop in the steel during creep.

The c-myb proto-oncogene and microRNA-15a comprise an active autoregulatory feedback loop in human hematopoietic cells

PubMed Central

Zhao, Huiwu; Kalota, Anna; Jin, Shenghao

2009-01-01

The c-myb proto-oncogene encodes an obligate hematopoietic cell transcription factor important for lineage commitment, proliferation, and differentiation. Given its critical functions, c-Myb regulatory factors are of great interest but remain incompletely defined. Herein we show that c-Myb expression is subject to posttranscriptional regulation by microRNA (miRNA)–15a. Using a luciferase reporter assay, we found that miR-15a directly binds the 3′-UTR of c-myb mRNA. By transfecting K562 myeloid leukemia cells with a miR-15a mimic, functionality of binding was shown. The mimic decreased c-Myb expression, and blocked the cells in the G1 phase of cell cycle. Exogenous expression of c-myb mRNA lacking the 3′-UTR partially rescued the miR-15a induced cell-cycle block. Of interest, the miR-15a promoter contained several potential c-Myb protein binding sites. Occupancy of one canonical c-Myb binding site was demonstrated by chromatin immunoprecipitation analysis and shown to be required for miR-15a expression in K562 cells. Finally, in studies using normal human CD34+ cells, we showed that c-Myb and miR-15a expression were inversely correlated in cells undergoing erythroid differentiation, and that overexpression of miR-15a blocked both erythroid and myeloid colony formation in vitro. In aggregate, these findings suggest the presence of a c-Myb–miR-15a autoregulatory feedback loop of potential importance in human hematopoiesis. PMID:18818396

17 CFR 240.15c1-2 - Fraud and misrepresentation.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Fraud and misrepresentation. 240.15c1-2 Section 240.15c1-2 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION... Securities Exchange Act of 1934 Rules Relating to Over-The-Counter Markets § 240.15c1-2 Fraud and...

Extension of the carotenoid test to superficially porous C18 bonded phases, aromatic ligand types and new classical C18 bonded phases.

PubMed

Lesellier, E

2012-11-30

The recent introduction of new stationary phases for liquid chromatography based on superficially porous particles, called core-shell or fused-core, dramatically improved the separation performances through very high efficiency, due mainly to reduced eddy diffusion. However, few studies have evaluated the retention and selectivity of C18 phases based on such particles, despite some retention order change reported in literature between some of these phases. The carotenoid test has been developed a few years ago in the goal to compare the chromatographic properties of C18 bonded phases. Based on the analysis of carotenoid pigments by using Supercritical Fluid Chromatography (SFC), it allows, with a single analysis, to measure three main properties of reversed phase chromatography stationary phases: hydrophobicity, polar surface activity and shape selectivity. Previous studies showed the effect of the endcapping treatment, the bonding density, the pore size, and the type of bonding (monomeric vs. polymeric) on these studied properties, and described the classification map used for a direct column comparison. It was applied to ten ODS superficially porous stationary phases, showing varied chromatographic behaviors amongst these phases. As expected, due to the lower specific surface area, these superficially porous phases are less hydrophobic than the fully porous one. In regards of the polar surface activity (residual silanols) and to the shape selectivity, some of these superficially porous phases display close chromatographic properties (Poroshell 120, Halo C18, Ascentis Express, Accucore C18, Nucleoshell C18 on one side and Aeris Wide pore, Aeris peptide and Kinetex XDB on the other side), whereas others, Kinetex C18 and Halo peptide ES C18 display more specific ones. Besides, they can be compared to classical fully porous phases, in the goal to improve method transfer from fully to superficially porous particles. By the way, the paper also report the extension of

Phase Transition Enthalpy Measurements of Organic and Organometallic Compounds. Sublimation, Vaporization and Fusion Enthalpies From 1880 to 2015. Part 1. C{sub 1} − C{sub 10}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Acree, William; Chickos, James S.

2016-09-15

A compendium of phase change enthalpies published in 2010 is updated to include the period 1880–2015. Phase change enthalpies including fusion, vaporization, and sublimation enthalpies are included for organic, organometallic, and a few inorganic compounds. Part 1 of this compendium includes organic compounds from C{sub 1} to C{sub 10}. Part 2 of this compendium, to be published separately, will include organic and organometallic compounds from C{sub 11} to C{sub 192}. Sufficient data are presently available to permit thermodynamic cycles to be constructed as an independent means of evaluating the reliability of the data. Temperature adjustments of phase change enthalpies frommore » the temperature of measurement to the standard reference temperature, T = 298.15 K, and a protocol for doing so are briefly discussed.« less

A phase one AR/C system design

NASA Technical Reports Server (NTRS)

Kachmar, Peter M.; Polutchko, Robert J.; Matusky, Martin; Chu, William; Jackson, William; Montez, Moises

1991-01-01

The Phase One AR&C System Design integrates an evolutionary design based on the legacy of previous mission successes, flight tested components from manned Rendezvous and Proximity Operations (RPO) space programs, and additional AR&C components validated using proven methods. The Phase One system has a modular, open architecture with the standardized interfaces proposed for Space Station Freedom system architecture.

Single-shot quantitative phase microscopy with color-multiplexed differential phase contrast (cDPC)

PubMed Central

2017-01-01

We present a new technique for quantitative phase and amplitude microscopy from a single color image with coded illumination. Our system consists of a commercial brightfield microscope with one hardware modification—an inexpensive 3D printed condenser insert. The method, color-multiplexed Differential Phase Contrast (cDPC), is a single-shot variant of Differential Phase Contrast (DPC), which recovers the phase of a sample from images with asymmetric illumination. We employ partially coherent illumination to achieve resolution corresponding to 2× the objective NA. Quantitative phase can then be used to synthesize DIC and phase contrast images or extract shape and density. We demonstrate amplitude and phase recovery at camera-limited frame rates (50 fps) for various in vitro cell samples and c. elegans in a micro-fluidic channel. PMID:28152023

Single-shot quantitative phase microscopy with color-multiplexed differential phase contrast (cDPC).

PubMed

Phillips, Zachary F; Chen, Michael; Waller, Laura

2017-01-01

We present a new technique for quantitative phase and amplitude microscopy from a single color image with coded illumination. Our system consists of a commercial brightfield microscope with one hardware modification-an inexpensive 3D printed condenser insert. The method, color-multiplexed Differential Phase Contrast (cDPC), is a single-shot variant of Differential Phase Contrast (DPC), which recovers the phase of a sample from images with asymmetric illumination. We employ partially coherent illumination to achieve resolution corresponding to 2× the objective NA. Quantitative phase can then be used to synthesize DIC and phase contrast images or extract shape and density. We demonstrate amplitude and phase recovery at camera-limited frame rates (50 fps) for various in vitro cell samples and c. elegans in a micro-fluidic channel.

In-phase thermomechanical fatigue mechanisms in an unidirectional SCS-6/Ti 15-3 MMC

NASA Technical Reports Server (NTRS)

Newaz, Golam M.; Majumdar, Bhaskar S.

1995-01-01

The objective of this investigation was to identify the inelastic deformation and damage mechanisms under in-phase (IP) thermomechanical fatigue (TMF) in a unidirectional SCS-6/Ti 15-3 metal matrix composite (MMC). Load-controlled IP TMF tests were conducted at 300-538 C at various stress ranges in high-purity argon. A major emphasis of this work was to identify damage mechanism well before final fracture of specimens, rather than to generate life diagrams, to aid development of a realistic deformation/damage and life model.

Results from the BRACE 1.5 study: Climate change impacts of 1.5 C and 2 C warming

NASA Astrophysics Data System (ADS)

O'Neill, B. C.; Anderson, B.; Monaghan, A. J.; Ren, X.; Sanderson, B.; Tebaldi, C.

2017-12-01

In 2015, 195 countries negotiated the Paris Agreement on climate change, which set long-term goals of limiting global mean warming to well below 2 C and possibly 1.5 C. This event stimulated substantial scientific interest in climate outcomes and impacts on society associated with those levels of warming. Recently, the first set of global climate model simulations explicitly designed to meet those targets were undertaken with the Community Earth System Model (CESM) for use by the research community (Sanderson et al, accepted). The BRACE 1.5 project models societal impacts from these climate outcomes, combined with assumptions about future socioeconomic conditions according to the Shared Socioeconomic Pathways. These analyses build on a recently completed study of the Benefits of Reduced Anthropogenic Climate changE (BRACE), published as a set of 20 papers in Climatic Change, which examined the difference in impacts between two higher scenarios resulting in about 2.5 C and 3.7 C warming by late this century. BRACE 1.5 consists of a set of six papers to be submitted to a special collection in Environmental Research Letters that takes a similar approach but focuses on impacts at 1.5 and 2 C warming. We ask whether impacts differ substantially between the two climate scenarios, accounting for uncertainty in climate outcomes through the use of initial condition ensembles of CESM simulations, and in societal conditions by using alternative SSP-based development pathways. Impact assessment focuses on the health and agricultural sectors; modeling approaches include the use of a global mutli-region CGE model for economic analysis, both a process-based and an empirical crop model, a model of spatial population change, a model of climatic suitability for the aedes aegypti mosquito, and an epidemiological model of heat-related mortality. A methodological analysis also evaluates the use of climate model emulation techniques for providing climate information sufficient to

Expansion of antimonato polyoxovanadates with transition metal complexes: (Co(N3C5H15)2)2[{Co(N3C5H15)2}V15Sb6O42(H2O)]·5H2O and (Ni(N3C5H15)2)2[{Ni(N3C5H15)2}V15Sb6O42(H2O)]·8H2O.

PubMed

Antonova, Elena; Näther, Christian; Kögerler, Paul; Bensch, Wolfgang

2012-02-20

Two new polyoxovanadates (Co(N(3)C(5)H(15))(2))(2)[{Co(N(3)C(5)H(15))(2)}V(15)Sb(6)O(42)(H(2)O)]·5H(2)O (1) and (Ni(N(3)C(5)H(15))(2))(2)[{Ni(N(3)C(5)H(15))(2)}V(15)Sb(6)O(42)(H(2)O)]·8H(2)O (2) (N(3)C(5)H(15) = N-(2-aminoethyl)-1,3-propanediamine) were synthesized under solvothermal conditions and structurally characterized. In both structures the [V(15)Sb(6)O(42)(H(2)O)](6-) shell displays the main structural motif, which is strongly related to the {V(18)O(42)} archetype cluster. Both compounds crystallize in the triclinic space group P1 with a = 14.3438(4), b = 16.6471(6), c = 18.9186(6) Å, α = 87.291(3)°, β = 83.340(3)°, γ = 78.890(3)°, and V = 4401.4(2) Å(3) (1) and a = 14.5697(13), b = 15.8523(16), c = 20.2411(18) Å, α = 86.702(11)°, β = 84.957(11)°, γ = 76.941(11)°, and V = 4533.0(7) Å(3) (2). In the structure of 1 the [V(15)Sb(6)O(42)(H(2)O)](6-) cluster anion is bound to a [Co(N(3)C(5)H(15))(2)](2+) complex via a terminal oxygen atom. In the Co(2+)-centered complex, one of the amine ligands coordinates in tridentate mode and the second one in bidentate mode to form a strongly distorted CoN(5)O octahedron. Similarly, in compound 2 an analogous NiN(5)O complex is joined to the [V(15)Sb(6)O(42)(H(2)O)](6-) anion via the same attachment mode. A remarkable difference between the two compounds is the orientation of the noncoordinated propylamine group leading to intermolecular Sb···O contacts in 1 and to Sb···N interactions in 2. In the solid-state lattices of 1 and 2, two additional [M(N(3)C(5)H(15))(2)](2+) complexes act as countercations and are located between the [{M(N(3)C(5)H(15))(2)}V(15)Sb(6)O(42)(H(2)O)](4-) anions. Between the anions and cations strong N-H···O hydrogen bonds are observed. In both compounds the clusters are stacked along the b axis in an ABAB fashion with cations and water molecules occupying the space between the clusters. Magnetic characterization demonstrates that the Ni(2+) and Co(2+) cations do not

Development in high-grade dual phase steels with low C and Si design

NASA Astrophysics Data System (ADS)

Zhu, Guo-hui; Zhang, Xue-hui; Mao, Wei-min

2009-12-01

Cold rolled dual phase steels with low C and Si addition were investigated in terms of combination of composition and processing in order to improve mechanical properties and workability including welding and galvanizing. Mo and Cr could be used as alloying elements to partially replace C and Si to assure enough hardening ability of the steels and also give solute-hardening. Mo addition is more effective than Cr addition in terms of obtaining the required volume fraction of martensite and mechanical strength. The ferrite grain was effectively refined by addition of Nb microalloying, which gives optimized mechanical properties. The experimental results show that it is possible to obtain the required mechanical properties of high grade 800 MPa dual phase steel, i.e., tensile strength > 780 MPa, elongation > 15%, and yield/tensile strength ratio < 0.6 in the condition of low carbon (C < 0.11 wt.%) and low silicon design (Si < 0.05 wt.%) through adequate combination of composition and processing.

Global drought and severe drought-affected populations in 1.5 and 2 °C warmer worlds

NASA Astrophysics Data System (ADS)

Liu, Wenbin; Sun, Fubao; Lim, Wee Ho; Zhang, Jie; Wang, Hong; Shiogama, Hideo; Zhang, Yuqing

2018-03-01

The 2015 Paris Agreement proposed a more ambitious climate change mitigation target on limiting global warming to 1.5 °C instead of 2 °C above preindustrial levels. Scientific investigations on environmental risks associated with these warming targets are necessary to inform climate policymaking. Based on the Coupled Model Intercomparison Project phase 5 (CMIP5) climate models, we present the first risk-based assessment of changes in global drought and the impact of severe drought on populations from additional 1.5 and 2 °C warming conditions. Our results highlight the risk of drought on a global scale and in several hotspot regions such as the Amazon, northeastern Brazil, southern Africa and Central Europe at both 1.5 and 2 °C global warming relative to the historical period, showing increases in drought durations from 2.9 to 3.2 months. Correspondingly, more total and urban populations would be exposed to severe droughts globally (+132.5 ± 216.2 million and +194.5 ± 276.5 million total population and +350.2 ± 158.8 million and +410.7 ± 213.5 million urban populations in 1.5 and 2 °C warmer worlds) and regionally (e.g., East Africa, West Africa and South Asia). Less rural populations (-217.7 ± 79.2 million and -216.2 ± 82.4 million rural populations in 1.5 and 2 °C warmer worlds) would be exposed to severe drought globally under climate warming, population growth and especially the urbanization-induced population migration. By keeping global warming at 1.5 °C above the preindustrial levels instead of 2 °C, there is a decrease in drought risks (i.e., less drought duration, less drought intensity and severity but relatively more frequent drought) and the affected total, urban and rural populations would decrease globally and in most regions. While challenging for both East Africa and South Asia, the benefits of limiting warming to below 1.5 °C in terms of global drought risk and impact reduction are significant.

Mechanical properties and microstructural evolution of modified 9Cr-1Mo steel after long-term aging for 50,000 h

NASA Astrophysics Data System (ADS)

Baek, Jong-Hyuk; Kim, Sung-Ho; Lee, Chan-Bock; Hahn, Do-Hee

2009-08-01

The mechanical properties and microstructural evolution of modified 9Cr-1Mo steel have been studied to investigate steel property changes after long-term isothermal aging at 600 °C for 50,000 h. The microhardness and strength were maintained constantly after aging but the impact energy was dramatically reduced by 62 % during the aging period. From the viewpoint of microstructural evolution after the aging process, Cr-enrichment and Fe-depletion took place within the M23C6-type precipitates in the as-aged steel and V-depletion also happened within the VX-type precipitates after aging. In addition, the precipitates of the M2Mo-type Laves phase and the segregation of the impurity atoms would be formed during the long-term aging period. It was considered that the sharp reduction of the impact energy could be related to the formation of the Laves phases and the impurity segregation after aging at 600 °C. The phase stability was also verified by the specific heat results up to 950 °C from a DSC test. It was concluded from this study that the modified 9Cr-1Mo steel would keep its microstructural stability at 600 °C during the long-term aging period of 50,000 h, which was equivalent to the in-service life of the SFR fuel cladding.

Multiple topological electronic phases in superconductor MoC

NASA Astrophysics Data System (ADS)

Huang, Angus; Smith, Adam D.; Schwinn, Madison; Lu, Qiangsheng; Chang, Tay-Rong; Xie, Weiwei; Jeng, Horng-Tay; Bian, Guang

2018-05-01

The search for a superconductor with non-s -wave pairing is important not only for understanding unconventional mechanisms of superconductivity but also for finding new types of quasiparticles such as Majorana bound states. Materials with both topological band structure and superconductivity are promising candidates as p +i p superconducting states can be generated through pairing the spin-polarized topological surface states. In this work, the electronic and phonon properties of the superconductor molybdenum carbide (MoC) are studied with first-principles methods. Our calculations show that nontrivial band topology and s -wave Bardeen-Cooper-Schrieffer superconductivity coexist in two structural phases of MoC, namely the cubic α and hexagonal γ phases. The α phase is a strong topological insulator and the γ phase is a topological nodal-line semimetal with drumhead surface states. In addition, hole doping can stabilize the crystal structure of the α phase and elevate the transition temperature in the γ phase. Therefore, MoC in different structural forms can be a practical material platform for studying topological superconductivity.

Long-term behaviour of solid oxide fuel cell interconnect materials in contact with Ni-mesh during exposure in simulated anode gas at 700 and 800 °C

NASA Astrophysics Data System (ADS)

Garcia-Fresnillo, L.; Shemet, V.; Chyrkin, A.; de Haart, L. G. J.; Quadakkers, W. J.

2014-12-01

In the present study the long-term behaviour of two ferritic steels, Crofer 22 APU and Crofer 22H, in contact with a Ni-mesh during exposure in simulated anode gas, Ar-4%H2-2%H2O, at 700 and 800 °C for exposure times up to 3000 h was investigated. Ni diffusion from the Ni-mesh into the steel resulted in the formation of an austenitic zone whereas diffusion of iron and chromium from the steel into the Ni-mesh resulted in the formation of chromia base oxides in the Ni-mesh. Depending on the chemical composition of the steel, the temperature and the exposure time, interdiffusion processes between ferritic steel and Ni-mesh also resulted in σ-phase formation at the austenite-ferrite interface and in Laves-phase dissolution in the austenitic zone. The extent and morphology of the σ-phase formation are discussed on the basis of thermodynamic considerations, including reaction paths in the ternary alloy system Fe-Ni-Cr.

Coordinating AgMIP data and models across global and regional scales for 1.5°C and 2.0°C assessments

NASA Astrophysics Data System (ADS)

Rosenzweig, Cynthia; Ruane, Alex C.; Antle, John; Elliott, Joshua; Ashfaq, Muhammad; Chatta, Ashfaq Ahmad; Ewert, Frank; Folberth, Christian; Hathie, Ibrahima; Havlik, Petr; Hoogenboom, Gerrit; Lotze-Campen, Hermann; MacCarthy, Dilys S.; Mason-D'Croz, Daniel; Contreras, Erik Mencos; Müller, Christoph; Perez-Dominguez, Ignacio; Phillips, Meridel; Porter, Cheryl; Raymundo, Rubi M.; Sands, Ronald D.; Schleussner, Carl-Friedrich; Valdivia, Roberto O.; Valin, Hugo; Wiebe, Keith

2018-05-01

The Agricultural Model Intercomparison and Improvement Project (AgMIP) has developed novel methods for Coordinated Global and Regional Assessments (CGRA) of agriculture and food security in a changing world. The present study aims to perform a proof of concept of the CGRA to demonstrate advantages and challenges of the proposed framework. This effort responds to the request by the UN Framework Convention on Climate Change (UNFCCC) for the implications of limiting global temperature increases to 1.5°C and 2.0°C above pre-industrial conditions. The protocols for the 1.5°C/2.0°C assessment establish explicit and testable linkages across disciplines and scales, connecting outputs and inputs from the Shared Socio-economic Pathways (SSPs), Representative Agricultural Pathways (RAPs), Half a degree Additional warming, Prognosis and Projected Impacts (HAPPI) and Coupled Model Intercomparison Project Phase 5 (CMIP5) ensemble scenarios, global gridded crop models, global agricultural economics models, site-based crop models and within-country regional economics models. The CGRA consistently links disciplines, models and scales in order to track the complex chain of climate impacts and identify key vulnerabilities, feedbacks and uncertainties in managing future risk. CGRA proof-of-concept results show that, at the global scale, there are mixed areas of positive and negative simulated wheat and maize yield changes, with declines in some breadbasket regions, at both 1.5°C and 2.0°C. Declines are especially evident in simulations that do not take into account direct CO2 effects on crops. These projected global yield changes mostly resulted in increases in prices and areas of wheat and maize in two global economics models. Regional simulations for 1.5°C and 2.0°C using site-based crop models had mixed results depending on the region and the crop. In conjunction with price changes from the global economics models, productivity declines in the Punjab, Pakistan, resulted in

Coordinating AgMIP data and models across global and regional scales for 1.5°C and 2.0°C assessments.

PubMed

Rosenzweig, Cynthia; Ruane, Alex C; Antle, John; Elliott, Joshua; Ashfaq, Muhammad; Chatta, Ashfaq Ahmad; Ewert, Frank; Folberth, Christian; Hathie, Ibrahima; Havlik, Petr; Hoogenboom, Gerrit; Lotze-Campen, Hermann; MacCarthy, Dilys S; Mason-D'Croz, Daniel; Contreras, Erik Mencos; Müller, Christoph; Perez-Dominguez, Ignacio; Phillips, Meridel; Porter, Cheryl; Raymundo, Rubi M; Sands, Ronald D; Schleussner, Carl-Friedrich; Valdivia, Roberto O; Valin, Hugo; Wiebe, Keith

2018-05-13

The Agricultural Model Intercomparison and Improvement Project (AgMIP) has developed novel methods for Coordinated Global and Regional Assessments (CGRA) of agriculture and food security in a changing world. The present study aims to perform a proof of concept of the CGRA to demonstrate advantages and challenges of the proposed framework. This effort responds to the request by the UN Framework Convention on Climate Change (UNFCCC) for the implications of limiting global temperature increases to 1.5°C and 2.0°C above pre-industrial conditions. The protocols for the 1.5°C/2.0°C assessment establish explicit and testable linkages across disciplines and scales, connecting outputs and inputs from the Shared Socio-economic Pathways (SSPs), Representative Agricultural Pathways (RAPs), Half a degree Additional warming, Prognosis and Projected Impacts (HAPPI) and Coupled Model Intercomparison Project Phase 5 (CMIP5) ensemble scenarios, global gridded crop models, global agricultural economics models, site-based crop models and within-country regional economics models. The CGRA consistently links disciplines, models and scales in order to track the complex chain of climate impacts and identify key vulnerabilities, feedbacks and uncertainties in managing future risk. CGRA proof-of-concept results show that, at the global scale, there are mixed areas of positive and negative simulated wheat and maize yield changes, with declines in some breadbasket regions, at both 1.5°C and 2.0°C. Declines are especially evident in simulations that do not take into account direct CO 2 effects on crops. These projected global yield changes mostly resulted in increases in prices and areas of wheat and maize in two global economics models. Regional simulations for 1.5°C and 2.0°C using site-based crop models had mixed results depending on the region and the crop. In conjunction with price changes from the global economics models, productivity declines in the Punjab, Pakistan, resulted in

Anisotropy induced anomalies in Dy 1$-$xTb xAl 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khan, M.; Miami Univ., Oxford, OH; Pathak, A. K.

2017-01-02

The Dy 1$-$xTb xAl 2 alloys have been investigated by X-ray powder diffraction, heat capacity, and magnetic measurements. All samples exhibit cubic Laves phase crystal structure at room temperature but at T C, DyAl2 and TbAl 2 show tetragonal and rhombohedral distortions, respectively. First order phase transitions are observed below T C (at the spin-reorientation transition, T SR) in the alloys with 0.15 ≤ x ≤ 0.35. These transitions are signified by sharp heat capacity peaks and corresponding anomalies in the magnetization and ac magnetic susceptibility data. The observations are interpreted by taking into consideration the differences in easy magnetizationmore » directions of DyAl 2 and TbAl 2. Due to the competing magnetic structures, the anisotropy-related instability and magnetic frustrations are prominent in the Dy 1$-$xTb xAl 2 alloys at certain concentrations resulting in the first order transitions.« less

Precipitation kinetics during aging of an alumina-forming austenitic stainless steel

DOE PAGES

Trotter, Geneva; Hu, Bin; Sun, Annie Y.; ...

2016-04-28

The microstructural evolution of DAFA26, an alumina-forming austenitic (AFA) stainless steel, was investigated during aging. The effect of aging at 750 °C and 800 °C on the growth of spherical γ’-Ni 3(Al, Ti) particles present in the as-processed state was studied extensively using X-ray diffraction, microhardness testing, scanning electron microscopy, transmission electron microscopy, and atom probe tomography. The γ’ particles had a cube-on-cube orientation relationship with the matrix (i.e. ((010)(010) m//(010)(010) p, [100][100] m//[100][100] p)). The coarsening kinetics of γ’-Ni 3Al particles were in agreement with the Lifshitz, Slyozof-Wagner theory. Coarse Laves phase particles were also present in the as-processedmore » state, and during the aging process both smaller Laves phase precipitates and B2-NiAl precipitates formed on both the grain boundaries and in the matrix. As a result, the γ’ precipitates were determined to have the most impact on the room temperature hardness.« less

Precipitation kinetics during aging of an alumina-forming austenitic stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trotter, Geneva; Hu, Bin; Sun, Annie Y.

The microstructural evolution of DAFA26, an alumina-forming austenitic (AFA) stainless steel, was investigated during aging. The effect of aging at 750 °C and 800 °C on the growth of spherical γ’-Ni 3(Al, Ti) particles present in the as-processed state was studied extensively using X-ray diffraction, microhardness testing, scanning electron microscopy, transmission electron microscopy, and atom probe tomography. The γ’ particles had a cube-on-cube orientation relationship with the matrix (i.e. ((010)(010) m//(010)(010) p, [100][100] m//[100][100] p)). The coarsening kinetics of γ’-Ni 3Al particles were in agreement with the Lifshitz, Slyozof-Wagner theory. Coarse Laves phase particles were also present in the as-processedmore » state, and during the aging process both smaller Laves phase precipitates and B2-NiAl precipitates formed on both the grain boundaries and in the matrix. As a result, the γ’ precipitates were determined to have the most impact on the room temperature hardness.« less

17 CFR 240.15c6-1 - Settlement cycle.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Settlement cycle. 240.15c6-1... Exchange Act of 1934 Rules Relating to Over-The-Counter Markets § 240.15c6-1 Settlement cycle. (a) Except... provides for payment of funds and delivery of securities later than the third business day after the date...

Arctic sea ice at 1.5 and 2 °C

NASA Astrophysics Data System (ADS)

Screen, James A.

2018-05-01

In the Paris Agreement, nations committed to a more ambitious climate policy target, aiming to limit global warming to 1.5 °C rather than 2 °C above pre-industrial levels. Climate models now show that achieving the 1.5 °C goal would make a big difference for Arctic sea ice.

Final Report of Tank 241-C-105 Dissolution, the Phase 2 Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meznarich, Huei K.; bolling, Stacey D.; Cooke, Gary A.

2016-10-01

Three clamshell grab samples were taken from Tank 241-C-105 in October 2015 in accordance with RPP-PLAN-60011. Analytical results of those samples were issued in the report RPP-RPT-59115 by Wastren Advantage, Inc., Hanford Laboratory. Solid phase characterization results were reported separately in LAB-RPT-15-00011 and in RPP-RPT-59147. The major solid phases reported to be present were dawsonite [NaAlCO 3(OH) 2], trona [Na 3(HCO 3)(CO 3)·2H 2O], cejkaite [Na 4(UO 2)(CO 3) 3], and an unidentified organic solid, with minor amounts of gibbsite [Al(OH) 3], natrophosphate [Na 7F(PO 4) 2·19H 2O], and traces of unidentified iron-rich and manganese-rich phases. Note that the presencemore » of dawsonite, trona, and cejkaite requires a relatively low pH, likely around pH 9 to 10. One aliquot of each grab sample was provided to 222-S Laboratory Process Chemistry for dissolution studies. Phase 1 of the dissolution testing followed the approved test plan, WRPS-1404813, Rev. 3, and examined the behavior of the Tank 241-C-105 solids treated with water, 19M sodium hydroxide, 2M nitric acid, and 0.5M oxalic acid/2M nitric acid. Phase 2 of the testing was conducted in accordance with instructions from the client and emphasized treatment with 19M sodium hydroxide followed by water washing. This is the report of the Phase 2 testing.« less

17 CFR 240.15c3-1a - Options (Appendix A to 17 CFR 240.15c3-1).

Code of Federal Regulations, 2013 CFR

2013-04-01

... Regulations Under the Securities Exchange Act of 1934 Rules Relating to Over-The-Counter Markets § 240.15c3-1a... and down) in the current market value of the underlying instrument equal to the percentage... life of the option; and (6) The current term structure of interest rates. (C) The term major market...

17 CFR 240.15c3-1a - Options (Appendix A to 17 CFR 240.15c3-1).

Code of Federal Regulations, 2010 CFR

2010-04-01

... Regulations Under the Securities Exchange Act of 1934 Rules Relating to Over-The-Counter Markets § 240.15c3-1a... and down) in the current market value of the underlying instrument equal to the percentage... life of the option; and (6) The current term structure of interest rates. (C) The term major market...

17 CFR 240.15c3-1a - Options (Appendix A to 17 CFR 240.15c3-1).

Code of Federal Regulations, 2011 CFR

2011-04-01

... Regulations Under the Securities Exchange Act of 1934 Rules Relating to Over-The-Counter Markets § 240.15c3-1a... and down) in the current market value of the underlying instrument equal to the percentage... life of the option; and (6) The current term structure of interest rates. (C) The term major market...

17 CFR 240.15c1-8 - Sales at the market.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Sales at the market. 240.15c1-8 Section 240.15c1-8 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION... Securities Exchange Act of 1934 Rules Relating to Over-The-Counter Markets § 240.15c1-8 Sales at the market...

Extreme heat waves under 1.5 °C and 2 °C global warming

NASA Astrophysics Data System (ADS)

Dosio, Alessandro; Mentaschi, Lorenzo; Fischer, Erich M.; Wyser, Klaus

2018-05-01

Severe, extreme, and exceptional heat waves, such as those that occurred over the Balkans (2007), France (2003), or Russia (2010), are associated with increased mortality, human discomfort and reduced labour productivity. Based on the results of a very high-resolution global model, we show that, even at 1.5 °C warming, a significant increase in heat wave magnitude is expected over Africa, South America, and Southeast Asia. Compared to a 1.5 °C world, under 2 °C warming the frequency of extreme heat waves would double over most of the globe. In a 1.5 °C world, 13.8% of the world population will be exposed to severe heat waves at least once every 5 years. This fraction becomes nearly three times larger (36.9%) under 2 °C warming, i.e. a difference of around 1.7 billion people. Limiting global warming to 1.5 °C will also result in around 420 million fewer people being frequently exposed to extreme heat waves, and ~65 million to exceptional heat waves. Nearly 700 million people (9.0% of world population) will be exposed to extreme heat waves at least once every 20 years in a 1.5 °C world, but more than 2 billion people (28.2%) in a 2 °C world. With current emission trends threatening even the 2 °C target, our study is helpful to identify regions where limiting the warming to 1.5 °C would have the strongest benefits in reducing population exposure to extreme heat.

Carbon-rich presolar grains from massive stars. Subsolar 12 C/ 13 C and 14 N/ 15 N ratios and the mystery of 15 N

DOE PAGES

Pignatari, M.; Zinner, E.; Hoppe, P.; ...

2015-07-30

We compared carbon-rich grains with isotopic anomalies to the Sun are found in primitive meteorites. They were made by stars, and carry the original stellar nucleosynthesis signature. Silicon carbide grains of Type X and C and low-density (LD) graphites condensed in the ejecta of core-collapse supernovae. Furthermore, we present a new set of models for the explosive He shell and compare them with the grains showing 12C/ 13C and 14N/ 15N ratios lower than solar. In the stellar progenitor H was ingested into the He shell and not fully destroyed before the explosion. All of the explosion energies and Hmore » concentrations are considered. If the supernova shock hits the He-shell region with some H still present, the models can reproduce the C and N isotopic signatures in C-rich grains. Hot-CNO cycle isotopic signatures are obtained, including a large production of 13C and 15N. The short-lived radionuclides 22Na and 26Al are increased by orders of magnitude. The production of radiogenic 22Ne from the decay of 22Na in the He shell might solve the puzzle of the Ne-E(L) component in LD graphite grains. This scenario is attractive for the SiC grains of type AB with 14N/ 15N ratios lower than solar, and provides an alternative solution for SiC grains originally classified as nova grains. Finally, this process may contribute to the production of 14N and 15N in the Galaxy, helping to produce the 14N/ 15N ratio in the solar system.« less

Application of unsymmetrical indirect covariance NMR methods to the computation of the (13)C <--> (15)N HSQC-IMPEACH and (13)C <--> (15)N HMBC-IMPEACH correlation spectra.

PubMed

Martin, Gary E; Hilton, Bruce D; Irish, Patrick A; Blinov, Kirill A; Williams, Antony J

2007-10-01

Utilization of long-range (1)H--(15)N heteronuclear chemical shift correlation has continually grown in importance since the first applications were reported in 1995. More recently, indirect covariance NMR methods have been introduced followed by the development of unsymmetrical indirect covariance processing methods. The latter technique has been shown to allow the calculation of hyphenated 2D NMR data matrices from more readily acquired nonhyphenated 2D NMR spectra. We recently reported the use of unsymmetrical indirect covariance processing to combine (1)H--(13)C GHSQC and (1)H--(15)N GHMBC long-range spectra to yield a (13)C--(15)N HSQC-HMBC chemical shift correlation spectrum that could not be acquired in a reasonable period of time without resorting to (15)N-labeled molecules. We now report the unsymmetrical indirect covariance processing of (1)H--(13)C GHMBC and (1)H--(15)N IMPEACH spectra to afford a (13)C--(15)N HMBC-IMPEACH spectrum that has the potential to span as many as six to eight bonds. Correlations for carbon resonances long-range coupled to a protonated carbon in the (1)H--(13)C HMBC spectrum are transferred via the long-range (1)H--(15)N coupling pathway in the (1)H--(15)N IMPEACH spectrum to afford a much broader range of correlation possibilities in the (13)C--(15)N HMBC-IMPEACH correlation spectrum. The indole alkaloid vincamine is used as a model compound to illustrate the application of the method. (c) 2007 John Wiley & Sons, Ltd.

Synthesis of MAX Phases in the Zr-Ti-Al-C System.

PubMed

Tunca, Bensu; Lapauw, Thomas; Karakulina, Olesia M; Batuk, Maria; Cabioc'h, Thierry; Hadermann, Joke; Delville, Rémi; Lambrinou, Konstantina; Vleugels, Jozef

2017-03-20

This study reports on the synthesis and characterization of MAX phases in the (Zr,Ti) n+1 AlC n system. The MAX phases were synthesized by reactive hot pressing and pressureless sintering in the 1350-1700 °C temperature range. The produced ceramics contained large fractions of 211 and 312 (n = 1, 2) MAX phases, while strong evidence of a 413 (n = 3) stacking was found. Moreover, (Zr,Ti)C, ZrAl 2 , ZrAl 3 , and Zr 2 Al 3 were present as secondary phases. In general, the lattice parameters of the hexagonal 211 and 312 phases followed Vegard's law over the complete Zr-Ti solid solution range, but the 312 phase showed a non-negligible deviation from Vegard's law around the (Zr 0.33 ,Ti 0.67 ) 3 Al 1.2 C 1.6 stoichiometry. High-resolution scanning transmission electron microscopy combined with X-ray diffraction demonstrated ordering of the Zr and Ti atoms in the 312 phase, whereby Zr atoms occupied preferentially the central position in the close-packed M 6 X octahedral layers. The same ordering was also observed in 413 stackings present within the 312 phase. The decomposition of the secondary (Zr,Ti)C phase was attributed to the miscibility gap in the ZrC-TiC system.

Morphological phase diagrams of C60 and C70 films on graphite

NASA Astrophysics Data System (ADS)

Sato, Kazuma; Tanaka, Tomoyasu; Akaike, Kouki; Kanai, Kaname

2017-10-01

The morphologies of C60 and C70 fullerene films vacuum-deposited onto graphite at various deposition rates and grown at several temperatures were investigated using atomic force microscopy. These fullerene films on graphite are model systems of physisorption of organic molecules that likely exhibit little chemical interaction with the graphite's surface. The morphologies of C60 and C70 films grown on graphite can be understood well from growth models previously reported. Comparison of the morphological phase diagrams obtained for C60 and C70 indicate that the diffusion properties of the adsorbed molecule are key in determining the morphology of the obtained film. The low diffusion rate of C70 resulted in various film morphologies for all deposition conditions tested. Also, the obtained phase diagrams can be understood by the results of fractal dimension analysis on the C60 and C70 islands. The fundamental understanding of film growth obtained using these ideal physisorption systems will aid in understanding film growth by other molecular adsorption systems.

Evaluation of phases in Pu-C-O and (U, Pu)-C-O systems by X-ray diffractometry and chemical analysis

NASA Astrophysics Data System (ADS)

Jain, G. C.; Ganguly, C.

1993-12-01

Preparation and characterisation of the carbides of uranium, plutonium and mixed uranium and plutonium form a part of advanced fuel development programs for fast breeder reactors. In the present study, the compositions of the phases of Pu-C-O and (U.Pu)-C-O systems have been determined by chemical analysis and lattice parameter measurement. The carbide samples have been prepared by vacuum carbothermic synthesis of tabletted oxide-graphite powder mixture. Dependence of stoichiometry of Pu 2C 3 phase on the oxygen content of Pu(C,O) phase in Pu(C,O) + Pu 2C 3 phase mixture has been evaluated. Stoichiometry and oxygen solubility of (U 0.3Pu 0.7)(C,O) phase in multiple phase mixture have been determined. Segregation of plutonium in (U,Pu) 2C 3 phase of (U,Pu)(C,O) + (U,Pu) 2C 3 phase mixture and its dependence on the oxygen content of (U,Pu)(C,O) phase have also been determined from the measurement of the lattice parameter of (U,Pu) 2C 3 phase.

Study of the mechanical behavior of the hydride blister/rim structure in Zircaloy-4 using in-situ synchrotron X-ray diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Jun-li; Han, Xiaochun; Heuser, Brent J.

2016-04-01

High-energy synchrotron X-ray diffraction was utilized to study the mechanical response of the f.c.c delta hydride phase, the intermetallic precipitation with hexagonal C14 lave phase and the alpha-Zr phase in the Zircaloy-4 materials with a hydride rim/blister structure near one surface of the material during in-situ uniaxial tension experiment at 200 degrees C. The f.c.c delta was the only hydride phase observed in the rim/blister structure. The conventional Rietveld refinement was applied to measure the macro-strain equivalent response of the three phases. Two regions were delineated in the applied load versus lattice strain measurement: a linear elastic strain region andmore » region that exhibited load partitioning. Load partitioning was quantified by von Mises analysis. The three phases were observed to have similar elastic modulus at 200 degrees C.« less

Effect of boron and carbon addition on microstructure and mechanical properties of the aged gamma-prime strengthened alumina-forming austenitic alloys [Effect of boron and carbon addition on microstructure and mechanical properties of the aged gamma-prime alumina-forming austenitic alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Bin; Trotter, Geneva; Wang, Zhangwei

Here, the goal of this work was to understand the effects of aging at 800 °C on the microstructures and mechanical properties of two recently-developed AFA stainless steels based on Fe-14Cr-32Ni-3Nb-3Al-2Ti (wt.%), one of which contained small additions of boron and carbon. To that end both the size distributions and growth kinetics of the B2, Laves phase, L1 2 precipitates present were quantified. While the lattice parameter, morphology, size and coarsening behavior of the L1 2 precipitates was the same in both AFA alloys, the B and C enhanced the grain boundary coverage by both Laves phase and B2-NiAl precipitates,more » but suppressed their coarsening. These interstitial additions also suppressed the formation of twins and discontinuous precipitation, which were observed in the B and C-free material. It is shown that the yield strength at 700 °C is largely controlled by the size of the L1 2 precipitates, with the largest strengthening effect obtained after aging for 2.4 h for both AFA alloys. Longer aging time led to a loss of strength mainly due to the coarsening of the L1 2 precipitates.« less

Effect of boron and carbon addition on microstructure and mechanical properties of the aged gamma-prime strengthened alumina-forming austenitic alloys [Effect of boron and carbon addition on microstructure and mechanical properties of the aged gamma-prime alumina-forming austenitic alloys

DOE PAGES

Hu, Bin; Trotter, Geneva; Wang, Zhangwei; ...

2017-07-03

Here, the goal of this work was to understand the effects of aging at 800 °C on the microstructures and mechanical properties of two recently-developed AFA stainless steels based on Fe-14Cr-32Ni-3Nb-3Al-2Ti (wt.%), one of which contained small additions of boron and carbon. To that end both the size distributions and growth kinetics of the B2, Laves phase, L1 2 precipitates present were quantified. While the lattice parameter, morphology, size and coarsening behavior of the L1 2 precipitates was the same in both AFA alloys, the B and C enhanced the grain boundary coverage by both Laves phase and B2-NiAl precipitates,more » but suppressed their coarsening. These interstitial additions also suppressed the formation of twins and discontinuous precipitation, which were observed in the B and C-free material. It is shown that the yield strength at 700 °C is largely controlled by the size of the L1 2 precipitates, with the largest strengthening effect obtained after aging for 2.4 h for both AFA alloys. Longer aging time led to a loss of strength mainly due to the coarsening of the L1 2 precipitates.« less

An Overview of the Effects of Alloying Elements on the Properties of Lightweight Fe-(15-35) Mn-(5-12) Al-(0.3-1.2) C Steel

NASA Astrophysics Data System (ADS)

Xing, Jia; Wei, Yinghui; Hou, Lifeng

2018-06-01

In this review, the influences of alloying elements on the phase constitution, density, and stacking fault energy of Fe-(15-35) Mn-(5-12) Al-(0.3-1.2) C lightweight steel are discussed. The mechanical properties of austenite single-phase and austenite-ferrite dual-phase Fe-Mn-Al-C steels processed by different procedures are also statistically analyzed. The austenite single-phase steel was found to possess superior strength and plasticity. Three reasonable explanations for the mechanism of plastic deformation are presented, namely, shear band-induced plasticity, microband-induced plasticity, and slip band refinement-induced plasticity.

An Overview of the Effects of Alloying Elements on the Properties of Lightweight Fe-(15-35) Mn-(5-12) Al-(0.3-1.2) C Steel

NASA Astrophysics Data System (ADS)

Xing, Jia; Wei, Yinghui; Hou, Lifeng

2018-04-01

In this review, the influences of alloying elements on the phase constitution, density, and stacking fault energy of Fe-(15-35) Mn-(5-12) Al-(0.3-1.2) C lightweight steel are discussed. The mechanical properties of austenite single-phase and austenite-ferrite dual-phase Fe-Mn-Al-C steels processed by different procedures are also statistically analyzed. The austenite single-phase steel was found to possess superior strength and plasticity. Three reasonable explanations for the mechanism of plastic deformation are presented, namely, shear band-induced plasticity, microband-induced plasticity, and slip band refinement-induced plasticity.

Australian climate extremes at 1.5 °C and 2 °C of global warming

NASA Astrophysics Data System (ADS)

King, Andrew D.; Karoly, David J.; Henley, Benjamin J.

2017-06-01

To avoid more severe impacts from climate change, there is international agreement to strive to limit warming to below 1.5 °C. However, there is a lack of literature assessing climate change at 1.5 °C and the potential benefits in terms of reduced frequency of extreme events. Here, we demonstrate that existing model simulations provide a basis for rapid and rigorous analysis of the effects of different levels of warming on large-scale climate extremes, using Australia as a case study. We show that limiting warming to 1.5 °C, relative to 2 °C, would perceptibly reduce the frequency of extreme heat events in Australia. The Australian continent experiences a variety of high-impact climate extremes that result in loss of life, and economic and environmental damage. Events similar to the record-hot summer of 2012-2013 and warm seas associated with bleaching of the Great Barrier Reef in 2016 would be substantially less likely, by about 25% in both cases, if warming is kept to lower levels. The benefits of limiting warming on hydrometeorological extremes are less clear. This study provides a framework for analysing climate extremes at 1.5 °C global warming.

Crystal structure of hexagonal MnAl(4).

PubMed

Pauling, L

1987-06-01

A structure is proposed for the hexagonal form of MnAl(4), with a(H) = 28.4 A and c(H) = 12.43 A, on the basis of a high-resolution electron micrograph and comparison with crystals of known structures. The proposed structure involves seven 104-atom complexes of 20 Friauf polyhedra, sharing some atoms with one another. It is closely related to the 23.36-A cubic structure of MnAl(4) and to the 14.19-A cubic structure of Mg(32)(Al,Zn)(49).

Space station MSFC-DPD-235/DR no. MA-05 phase C/D program development plan. Volume 2: Phase C/D, programmatic requirements

NASA Technical Reports Server (NTRS)

1971-01-01

The design plan requirements define the design implementation and control requirements for Phase C/D of the Modular Space Station Project and specifically address the Initial Space Station phase of the Space Station Program (modular). It is based primarily on the specific objective of translating the requirements of the Space Station Program, Project, Interface, and Support Requirements and preliminary contract end x item specifications into detail design of the operational systems which comprise the initial space station. This document is designed to guide aerospace contractors in the planning and bidding for Phase C/D.

Temperature induced phase transition of CaMn{sub 0.5}Zr{sub 1.5}(PO{sub 4}){sub 3} phosphate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orlova, Maria, E-mail: maria.p.orlova@gmail.com; Perfler, Lukas; Tribus, Martina

2016-03-15

In this work we investigated the structural behaviour of a CaMn{sub 0.5}Zr{sub 1.5}(PO{sub 4}){sub 3}. Due to the presence of divalent Mn{sup 2+} cations this compound can possess interesting luminescence properties. It was recently understood that this phosphate undergoes a temperature induced irreversible phase transition in the range of 800–875 °C. It has also been shown that the 3d–3d luminescence of Mn{sup 2+} increases 10 fold for the high temperature polymorph. To determine the Mn environment structural investigations of both phases have been performed by the X-ray powder diffraction and Raman spectroscopy methods. The low temperature modification adopts the trigonalmore » NZP structure type with a slightly lower symmetry (space group R32, a=8.7850(2) Å, c=22.6496(7) Å, V=1514.8(1) Å{sup 3}). The high temperature form in turn has orthorhombic symmetry (space group Pnma, a=6.2350(3) Å, b=6.6281(3) Å, c=14.4731(6) Å, V=598.13(5) Å{sup 3}). Both structures were solved ab-initio from powder data and structural analysis was performed. In-situ and RT Raman spectra are consistent with the XRD derived structural model. Mn{sup 2+} cations occupy different types of positions in these structures and a change in Mn coordination number (6 for LT phase, 7 for HT phase) results in different Mn–O bond lengths. These differences may explain the change in the optical properties between the polymorphs. - Graphical abstract: The compound CaMn{sub 0.5}Zr{sub 1.5}(PO{sub 4}){sub 3} was synthesized in order to create a material with enhanced luminescent properties. The goal of present studies is to define Mn{sup 2+} environment and its changes due to the structural transformations of the phosphate along phase transition at the T range of 800–875 °C. It was found that LT modification adopts the trigonal NZP structure type, sp.gr. R32, the HT form in turn exhibits orthorhombic symmetry sp.gr. Pnma. Mn2+ cations occupy different types of positions in those

HRTEM and chemical study of an ion-irradiated chromium/zircaloy-4 interface

NASA Astrophysics Data System (ADS)

Wu, A.; Ribis, J.; Brachet, J.-C.; Clouet, E.; Leprêtre, F.; Bordas, E.; Arnal, B.

2018-06-01

Chromium-coated zirconium alloys are being studied as Enhanced Accident Tolerant Fuel Cladding for Light Water Reactors (LWRs). Those materials are especially studied to improve the oxidation resistance of LWRs current fuel claddings in nominal and at High Temperature (HT) for hypothetical accidental conditions such as LOss of Coolant Accident. Beyond their HT behavior, it is essential to assess the materials behavior under irradiation. A first generation chromium/Zircaloy-4 interface was thus irradiated with 20 MeV Kr8+ ions at 400 °C up to 10 dpa. High-Resolution Transmission Electron Microscopy and chemical analysis (EDS) were conducted at the Cr/Zr interface. The atomic structure of the interface reveals the presence of Zr(Fe, Cr)2 Laves phase, displaying both C14 and C15 structure. After irradiation, only the C14 structure was observed and atomic row matching was preserved across the different interfaces, thus ensuring a good adhesion of the coating after irradiation.

Arctic Sea Ice in a 1.5°C Warmer World

NASA Astrophysics Data System (ADS)

Niederdrenk, Anne Laura; Notz, Dirk

2018-02-01

We examine the seasonal cycle of Arctic sea ice in scenarios with limited future global warming. To do so, we analyze two sets of observational records that cover the observational uncertainty of Arctic sea ice loss per degree of global warming. The observations are combined with 100 simulations of historical and future climate evolution from the Max Planck Institute Earth System Model Grand Ensemble. Based on the high-sensitivity observations, we find that Arctic September sea ice is lost with low probability (P≈ 10%) for global warming of +1.5°C above preindustrial levels and with very high probability (P> 99%) for global warming of +2°C above preindustrial levels. For the low-sensitivity observations, September sea ice is extremely unlikely to disappear for +1.5°C warming (P≪ 1%) and has low likelihood (P≈ 10%) to disappear even for +2°C global warming. For March, both observational records suggest a loss of 15% to 20% of Arctic sea ice area for 1.5°C to 2°C global warming.

Installation Restoration Program. Phase 1. Records Search 15th ABW Satellite Installations, Hawaii

DTIC Science & Technology

1984-09-01

Hickam POL Storage Facilities and Pipeline The POL storage facilities remotely located from Hickam Air Force Base (AFB...airfield with less activity than nearby Wheeler and Hickam Air Force Bases . Aircraft activity was significantly reduced in the late 1940’s and the...United States Air Force to conduct the Phase I Records Search at the 15th Air Base Wing 1-2 ES ENGINEERING-SCIENCE PHASE I PHASE 11 PHASE IV

Intermetallic Strengthened Alumina-Forming Austenitic Steels for Energy Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Bin; Baker, Ian

2016-03-31

In order to achieve energy conversion efficiencies of >50 % for steam turbines/boilers in power generation systems, the materials required must be strong, corrosion-resistant at high temperatures (>700°C), and economically viable. Austenitic steels strengthened with Laves phase and L1 2 precipitates, and alloyed with aluminum to improve oxidation resistance, are potential candidate materials for these applications. The creep resistance of these alloys is significantly improved through intermetallic strengthening (Laves-Fe 2Nb + L1 2-Ni 3Al precipitates) without harmful effects on oxidation resistance. Microstructural and microchemical analyses of the recently developed alumina-forming austenitic (AFA) steels (Fe-14Cr-32Ni-3Nb-3Al-2Ti-based) indicated they are strengthened by Nimore » 3Al(Ti) L1 2, NiAl B 2, Fe 2Nb Laves phase and MC carbide precipitates. Different thermomechanical treatments (TMTs) were performed on these stainless steels in an attempt to further improve their mechanical properties. The thermo-mechanical processing produced nanocrystalline grains in AFA alloys and dramatically increased their yield strength at room temperature. Unfortunately, the TMTs didn’t increase the yield strengths of AFA alloys at ≥700ºC. At these temperatures, dislocation climb is the dominant mechanism for deformation of TMT alloys according to strain rate jump tests. After the characterization of aged AFA alloys, we found that the largest strengthening effect from L1 2 precipitates can be obtained by aging for less than 24 h. The coarsening behavior of the L1 2 precipitates was not influenced by carbon and boron additions. Failure analysis and post-mortem TEM analysis were performed to study the creep failure mechanisms of these AFA steels after creep tests. Though the Laves and B2-NiAl phase precipitated along the boundaries can improve the creep properties, cracks were still initiated and propagated along the boundaries, which suggests that the boundaries are

BMP15 c.-9C>G promoter sequence variant may contribute to the cause of non-syndromic premature ovarian failure.

PubMed

Fonseca, Dora Janeth; Ortega-Recalde, Oscar; Esteban-Perez, Clara; Moreno-Ortiz, Harold; Patiño, Liliana Catherine; Bermúdez, Olga María; Ortiz, Angela María; Restrepo, Carlos M; Lucena, Elkin; Laissue, Paul

2014-11-01

BMP15 has drawn particular attention in the pathophysiology of reproduction, as its mutations in mammalian species have been related to different reproductive phenotypes. In humans, BMP15 coding regions have been sequenced in large panels of women with premature ovarian failure (POF), but only some mutations have been definitely validated as causing the phenotype. A functional association between the BMP15 c.-9C>G promoter polymorphism and cause of POF have been reported. The aim of this study was to determine the potential functional effect of this sequence variant on specific BMP15 promoter transactivation disturbances. Bioinformatics was used to identify transcription factor binding sites located on the promoter region of BMP15. Reverse transcription polymerase chain reaction was used to study specific gene expression in ovarian tissue. Luciferase reporter assays were used to establish transactivation disturbances caused by the BMP15 c.-9C>G variant. The c.-9C>G variant was found to modify the PITX1 transcription factor binding site. PITX1 and BMP15 co-expressed in human and mouse ovarian tissue, and PITX1 transactivated both BMP15 promoter versions (-9C and -9G). It was found that the BMP15 c.-9G allele was related to BMP15 increased transcription, supporting c.-9C>G as a causal agent of POF. Copyright © 2014 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

A comparative study of the Aurivillius phase ferroelectrics CaBi 4Ti 4O 15 and BaBi 4Ti 4O 15

NASA Astrophysics Data System (ADS)

Tellier, J.; Boullay, Ph.; Manier, M.; Mercurio, D.

2004-06-01

The room temperature structures of the four-layer Aurivillius phase ferroelectrics CaBi 4Ti 4O 15 and BaBi 4Ti 4O 15 are determined by means of single crystal X-ray diffraction. Regarding the CaBi 4Ti 4O 15 phase, in agreement with the tolerance factor, a significant deformation of the perovskite blocks is observed. The rotation system of the octahedra is typical from even layer Aurivillius phases and leads to the use of the space group A2 1am. For the BaBi 4Ti 4O 15 phase, only a weak variation with respect to the F2 mm space group can be suggested from single crystal X-ray diffraction. A significant presence of Ba atoms in the [ M2O 2] slabs is confirmed in agreement with the previous works but specific Ba 2+ and Bi 3+ sites have to be considered due to the large difference in bounding requirement of these cations. Possible origins for the ferroelectric relaxor behavior of the Ba-based compound are discussed in view of the presented structural analyses.

Phase-locked tracking loops for LORAN-C

NASA Technical Reports Server (NTRS)

Burhans, R. W.

1978-01-01

Portable battery operated LORAN-C receivers were fabricated to evaluate simple envelope detector methods with hybrid analog to digital phase locked loop sensor processors. The receivers are used to evaluate LORAN-C in general aviation applications. Complete circuit details are given for the experimental sensor and readout system.

Projected drought risk in 1.5°C and 2°C warmer climates

NASA Astrophysics Data System (ADS)

Lehner, F.; Coats, S.; Stocker, T. F.; Pendergrass, A. G.; Sanderson, B. M.; Raible, C.; Smerdon, J. E.

2017-12-01

The large socioeconomic costs of droughts make them a crucial target for impact assessments of climate change scenarios. Using multiple drought metrics and a set of simulations with the Community Earth System Model (CESM) targeting 1.5°C and 2°C above preindustrial global mean temperatures, we investigate changes in aridity and the risk of consecutive drought years. The latter metric is motivated by recent droughts in California and the US Southwest in general, where consecutive years of moderate precipitation deficit can quickly lead to significant drought and elevated pressure on water resources. If warming is limited to 2°C, these simulations suggest little change in drought risk for the U.S. Southwest and Central Plains compared to present day, an interesting result that arises from a delicate balance between increases in evaporative demand and precipitation in CESM in that region. In the Mediterranean, central Europe, and a number of other regions across the globe, however, drought risk increases significantly for both 1.5°C and 2°C warming targets, and the additional 0.5°C of the 2°C climate leads to significantly higher drought risk. Our study suggests that limiting anthropogenic warming to 1.5°C rather than 2°C, as aspired to by the Paris Climate Agreement, may have benefits for future drought risk but that such benefits may be regional and in some cases highly uncertain. We will therefore also discuss the robustness of results across different drought metrics as well as the model uncertainties associated with drought projections for low warming targets.

Safety and efficacy of preoperative or postoperative chemotherapy for resectable pancreatic adenocarcinoma (PACT-15): a randomised, open-label, phase 2-3 trial.

PubMed

Reni, Michele; Balzano, Gianpaolo; Zanon, Silvia; Zerbi, Alessandro; Rimassa, Lorenza; Castoldi, Renato; Pinelli, Domenico; Mosconi, Stefania; Doglioni, Claudio; Chiaravalli, Marta; Pircher, Chiara; Arcidiacono, Paolo Giorgio; Torri, Valter; Maggiora, Paola; Ceraulo, Domenica; Falconi, Massimo; Gianni, Luca

2018-06-01

Pancreatic ductal adenocarcinoma are known to metastasise early and a rationale exists for the investigation of preoperative chemotherapy in patients with resectable disease. We aimed to assess the role of combination chemotherapy in this setting in the PACT-15 trial. We did this randomised, open-label, phase 2-3 trial in ten hospitals in Italy. We report the phase 2 part here. Patients aged 18-75 years who were previously untreated for pancreatic ductal adenocarcinoma, with Karnofsky performance status of more than 60, and pathologically confirmed stage I-II resectable disease were enrolled. Patients were randomly assigned (1:1:1), with a minimisation algorithm that stratified treatment allocation by centre and concentrations of carbohydrate antigen 19-9 (CA19-9 ≤5 × upper limit of normal [ULN] vs >5 × ULN), to receive surgery followed by adjuvant gemcitabine 1000 mg/m 2 on days 1, 8, 15 every 4 weeks for six cycles (arm A), surgery followed by six cycles of adjuvant PEXG (cisplatin 30 mg/m 2 , epirubicin 30 mg/m 2 , and gemcitabine 800 mg/m 2 on days 1 and 15 every 4 weeks and capecitabine 1250 mg/m 2 on days 1-28; arm B), or three cycles of PEXG before and three cycles after surgery (arm C). Patients and investigators who gave treatments or assessed outcomes were not masked to treatment allocation. The primary endpoint was the proportion of patients who were event-free at 1 year. The primary endpoint was analysed in the per-protocol population. Safety analysis was done for all patients receiving at least one dose of study treatment. The trial is registered with ClinicalTrials.gov, number NCT01150630. Between Oct 5, 2010, and May 30, 2015, 93 patients were randomly allocated to treatment. One centre was found to be non-compliant with the protocol, and all five patients at this centre were excluded from the study. Thus, 88 patients were included in the final study population: 26 in group A, 30 in group B, and 32 in group C. In the per

Elasticity of phase-Pi (Al3Si2O7(OH)3) - A hydrous aluminosilicate phase

NASA Astrophysics Data System (ADS)

Peng, Ye; Mookherjee, Mainak; Hermann, Andreas; Bajgain, Suraj; Liu, Songlin; Wunder, Bernd

2017-08-01

Phase-Pi (Al3Si2O7(OH)3) is an aluminosilicate hydrous mineral and is likely to be stable in hydrated sedimentary layers of subducting slabs. Phase-Pi is likely to be stable between the depths of 60 and 200 km and is likely to transport water into the Earth's interior. Here, we use first principles simulations based on density functional theory to explore the crystal structure at high-pressure, equation of state, and full elastic stiffness tensor as a function of pressure. We find that the pressure volume results could be described by a finite strain fit with V0 , K0 , and K0‧ being 310.3 Å3, 133 GPa, and 3.6 respectively. At zero pressure, the full elastic stiffness tensor shows significant anisotropy with the diagonal principal components C11 , C22 , and C33 being 235, 292, 266 GPa respectively, the diagonal shear C44 , C55 , and C66 being 86, 92, and 87 GPa respectively, and the off-diagonal stiffness C12 , C13 , C14 ,C15 , C16 , C23 , C24 , C25 , C26 , C34 , C35 , C36 , C45 , C46 , and C56 being 73, 78, 6, -30, 15, 61, 17, 2, 1, -13, -15, 6, 3, 1, and 3 GPa respectively. The zero pressure, shear modulus, G0 and its pressure derivative, G0 ‧ are 90 GPa and 1.9 respectively. Upon compression, hydrogen bonding in phase-Pi shows distinct behavior, with some hydrogen bonds weakening and others strengthening. The latter eventually undergo symmetrization, at pressure greater (>40 GPa) than the thermodynamic stability of phase-Pi. Full elastic constant tensors indicate that phase-Pi is very anisotropic with AVP ∼22.4% and AVS ∼23.7% at 0 GPa. Our results also indicate that the bulk sound velocity of phase-Pi is slower than that of the high-pressure hydrous aluminosilicate phase, topaz-OH.

The First in Vivo Observation of 13C- 15N Coupling in Mammalian Brain

NASA Astrophysics Data System (ADS)

Kanamori, Keiko; Ross, Brian D.

2001-12-01

[5-13C,15N]Glutamine, with 1J(13C-15N) of 16 Hz, was observed in vivo in the brain of spontaneously breathing rats by 13C MRS at 4.7 T. The brain [5-13C]glutamine peak consisted of the doublet from [5-13C,15N]glutamine and the center [5-13C,14N]glutamine peak, resulting in an apparent triplet with a separation of 8 Hz. The time course of formation of brain [5-13C,15N]glutamine was monitored in vivo with a time resolution of 20-35 min. This [5-13C,15N]glutamine was formed by glial uptake of released neurotransmitter [5-13C]glutamate and its reaction with 15NH3 catalyzed by the glia-specific glutamine synthetase. The neurotransmitter glutamate C5 was selectively13C-enriched by intravenous [2,5-13C]glucose infusion to 13C-label whole-brain glutamate C5, followed by [12C]glucose infusion to chase 13C from the small and rapidly turning-over glial glutamate pool, leaving 13C mainly in the neurotransmitter [5-13C]glutamate pool, which is sequestered in vesicles until release. Hence, the observed [5-13C,15N]glutamine arises from a coupling between 13C of neuronal origin and 15N of glial origin. Measurement of the rate of brain [5-13C,15N]glutamine formation provides a novel noninvasive method of studying the kinetics of neurotransmitter uptake into glia in vivo, a process that is crucial for protecting the brain from glutamate excitotoxicity.

Microstructure Development in Electron Beam-Melted Inconel 718 and Associated Tensile Properties

DOE PAGES

Kirka, M. M.; Unocic, K. A.; Raghavan, N.; ...

2016-02-12

During the electron beam melting (EBM) process, builds occur at temperatures in excess of 800°C for nickel-base superalloys such as Inconel 718. When coupled with the temporal differences between the start and end of a build, a top-to-bottom microstructure gradient forms. Characterized in this study is the microstructure gradient and associated tensile property gradient that are common to all EBM Inconel 718 builds. From the characteristic microstructure elements observed in EBM Inconel 718 material, the microstructure gradient can be classified into three distinct regions. Region 1 (top of a build) and is comprised of a cored dendritic structure that includesmore » carbides and Laves phase within the interdendritic regions. Region 2 is an intermediate transition zone characterized by a diffuse dendritic structure, dissolution of the Laves phase, and precipitation of δ needle networks within the interdendritic regions. The bulk structure (Region 3) is comprised of a columnar grain structure lacking dendritic characteristics with δ networks having precipitated within the grain interiors. Mechanically at both 20°C and 650° C, the yield strength, ultimate tensile strength, and elongation at failure exhibit the general trend of increasing with increasing build height.« less

Thermomechanical testing techniques for high-temparature composites: TMF behavior of SiC(SCS-6)/Ti-15-3

NASA Technical Reports Server (NTRS)

Castelli, Michael G.; Ellis, J. Rodney; Bartolotta, Paul A.

1990-01-01

Thermomechanical testing techniques recently developed for monolithic structural alloys were successfully extended to continuous fiber reinforced composite materials in plate form. The success of this adaptation was verified on a model metal matrix composite (MMC) material, namely SiC(SCS-6)/Ti-15V-3Cr-3Al-3Sn. Effects of heating system type and specimen preparation are also addressed. Cyclic lives determined under full thermo-mechanical conditions were shown to be significantly reduced from those obtained under comparable isothermal and in-phase bi-thermal conditions. Fractography and metallography from specimens subjected to isothermal, out-of-phase and in-phase conditions reveal distinct differences in damage-failure modes. Isothermal metallography revealed extensive matrix cracking associated with fiber damage throughout the entire cross-section of the specimen. Out-of-phase metallography revealed extensive matrix damage associated with minimal (if any) fiber cracking. However, the damage was located exclusively at surface and near-surface locations. In-phase conditions produced extensive fiber cracking throughout the entire cross-section, associated with minimal (if any) matrix damage.

15 CFR 8c.49 - Program accessibility: Discrimination prohibited.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Program accessibility: Discrimination prohibited. 8c.49 Section 8c.49 Commerce and Foreign Trade Office of the Secretary of Commerce ENFORCEMENT OF NONDISCRIMINATION ON THE BASIS OF HANDICAP IN PROGRAMS OR ACTIVITIES CONDUCTED BY THE DEPARTMENT OF COMMERCE § 8c.49...

15 CFR 8c.30 - General prohibitions against discrimination.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false General prohibitions against discrimination. 8c.30 Section 8c.30 Commerce and Foreign Trade Office of the Secretary of Commerce ENFORCEMENT OF NONDISCRIMINATION ON THE BASIS OF HANDICAP IN PROGRAMS OR ACTIVITIES CONDUCTED BY THE DEPARTMENT OF COMMERCE § 8c.30...

Differentiation regional climate impact indicators at 1.5°C and 2°C warming above pre-industrial levels

NASA Astrophysics Data System (ADS)

Schleussner, C. F.

2016-12-01

Robust appraisals of climate impacts at different levels of global-mean temperature increase are vital to guide assessments of dangerous anthropogenic interference with the climate system. By establishing 1.5°C as the long term temperature limit for global average temperature increase and inviting a special report of the IPCC on the impacts of 1.5°C, the Paris Agreement has put such assessments high on the post-Paris science agenda. Here I will present recent findings of climate impacts at 1.5°C, including extreme weather events, water availability, agricultural yields, sea-level rise and risk of coral reef loss. In particular, I will present findings from a recent study that attempts to differentiate between such impacts at warming levels of 1.5°¸C and 2°C above pre-industrial (Schleussner et al., 2016). By analyzing changes in indicators for 26 world regions as applicable, the study found regional dependent differences between a 1.5°C and 2°C warming. Regional hot-spots of change emerge with tropical regions bearing the brunt of the impacts of an additional 0.5°C warming. These findings highlight the importance of regional differentiation to assess both future climate risks and different vulnerabilities to incremental increases in global-mean temperature. Building on that analysis, I will discuss limitations of existing approaches to differentiate between warming levels and outline opportunities for future work on refining our understanding of the difference between impacts at 1.5°C and 2°C warming. ReferencesSchleussner, C.-F. et al. Differential climate impacts for policy relevant limits to global warming: the case of 1.5°C and 2°C. Earth Syst. Dyn. 7, 327-351 (2016).

Phase coexistence and high electrical properties in (KxNa0.96-xLi0.04)(Nb0.85Ta0.15)O3 piezoelectric ceramics

NASA Astrophysics Data System (ADS)

Chang, Yunfei; Yang, Zupei; Ma, Difei; Liu, Zonghuai; Wang, Zenglin

2009-03-01

(KxNa0.96-xLi0.04)(Nb0.85Ta0.15)O3 lead-free piezoelectric ceramics were produced by conventional solid-state reaction method. The effects of K/Na ratio on the phase transitional behavior, Raman spectrum, microstructure, and dielectric, piezoelectric, and ferroelectric properties of the ceramics have been investigated. The phase structure of the ceramics undergoes a transition from orthorhombic to tetragonal phase with increasing x. A double-degenerate symmetric O-Nb-O stretching vibration v1 and a triply degenerate symmetric O-Nb-O bending vibration v5 are detected as relatively strong scattering in the Raman spectra. The peak shifts of v5 and v1 modes all have a discontinuity with x between 0.42 and 0.46, which may suggest the coexistence of orthorhombic and tetragonal phases in this range. Properly modifying x reduces the sintering temperature, promotes the grain growth behavior, and improves the density of the ceramics. The polymorphic phase transition (at To -t) is shifted to near room temperature by increasing x to 0.44 (K/Na ratio of about 0.85:1), and the coexistence of orthorhombic and tetragonal phases in the ceramics at x =0.44 results in the optimized electrical properties (d33=291 pC/N, kp=0.54, ɛr=1167, tan δ=0.018, To -t=35 °C, TC=351 °C, Pr=27.65 μC/cm2, and Ec=8.63 kV/cm). The results show that the equal K/Na ratio is not an essential condition in obtaining optimized electrical properties in (KxNa0.96-xLi0.04)(Nb0.85Ta0.15)O3 ceramics.

Crystal structure of hexagonal MnAl4

PubMed Central

Pauling, Linus

1987-01-01

A structure is proposed for the hexagonal form of MnAl4, with aH = 28.4 Å and cH = 12.43 Å, on the basis of a high-resolution electron micrograph and comparison with crystals of known structures. The proposed structure involves seven 104-atom complexes of 20 Friauf polyhedra, sharing some atoms with one another. It is closely related to the 23.36-Å cubic structure of MnAl4 and to the 14.19-Å cubic structure of Mg32(Al,Zn)49. Images PMID:16593837

The nature of the structural phase transition from the hexagonal (4H) phase to the cubic (3C) phase of silver.

PubMed

Chakraborty, Indrani; Shirodkar, Sharmila N; Gohil, Smita; Waghmare, Umesh V; Ayyub, Pushan

2014-03-19

The phase transition from the hexagonal 4H polytype of silver to the commonly known 3C (fcc) phase was studied in detail using x-ray diffraction, electron microscopy, differential scanning calorimetry and Raman spectroscopy. The phase transition is irreversible and accompanied by extensive microstructural changes and grain growth. Detailed scanning and isothermal calorimetric analysis suggests that it is an autocatalytic transformation. Though the calorimetric data suggest an exothermic first-order phase transition with an onset at 155.6 °C (for a heating rate of 2 K min(-1)) and a latent heat of 312.9 J g(-1), the microstructure and the electrical resistance appear to change gradually from much lower temperatures. The 4H phase shows a Raman active mode at 64.3 cm(-1) (at 4 K) that undergoes mode softening as the 4H → 3C transformation temperature is approached. A first-principles density functional theory calculation shows that the stacking fault energy of 4H-Ag increases monotonically with temperature. That 4H-Ag has a higher density of stacking faults than 3C-Ag, implies the metastability of the former at higher temperatures. Energetically, the 4H phase is intermediate between the hexagonal 2H phase and the 3C ground state, as indicated by the spontaneous transformation of the 2H to the 4H phase at -4 °C. Our data appear to indicate that the 4H-Ag phase is stabilized at reduced dimensions and thermally induced grain growth is probably responsible for triggering the irreversible transformation to cubic Ag.

Infrared spectra of ovalene (C32H14) and hydrogenated ovalene (C32H15˙) in solid para-hydrogen.

PubMed

Tsuge, Masashi; Bahou, Mohammed; Wu, Yu-Jong; Allamandola, Louis; Lee, Yuan-Pern

2016-10-19

We report the infrared (IR) spectra of ovalene (C 32 H 14 ) and hydrogenated ovalene (C 32 H 15 ˙) in solid para-hydrogen (p-H 2 ). The hydrogenated ovalene and protonated ovalene were generated from electron bombardment of a mixture of ovalene and p-H 2 during deposition of a matrix at 3.2 K. The features that decreased with time have been previously assigned to 7-C 32 H 15 + , the most stable isomer of protonated ovalene (Astrophys. J., 2016, 825, 96). The spectral features that increased with time are assigned to the most stable isomer of hydrogenated ovalene (7-C 32 H 15 ˙) based on the expected chemistry and on a comparison with the vibrational wavenumbers and IR intensities predicted by the B3PW91/6-311++G(2d,2p) method. The mechanism of formation of 7-C 32 H 15 ˙ is discussed according to the observed changes in intensity and calculated energetics of possible reactions of H + C 32 H 14 and isomerization of C 32 H 15 ˙. The formation of 7-C 32 H 15 ˙ is dominated by the reaction H + C 32 H 14 → 7-C 32 H 15 ˙, implying that, regardless of the presence of a barrier, the hydrogenation of polycyclic aromatic hydrocarbons occurs even at 3.2 K.

FY15 Status of Immersion Phased Array Ultrasonic Probe Development and Performance Demonstration Results for Under Sodium Viewing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Diaz, Aaron A.; Larche, Michael R.; Mathews, Royce

2015-09-01

This Technical Letter Report (TLR) describes work conducted at the Pacific Northwest National Laboratory (PNNL) during FY 2015 on the under-sodium viewing (USV) PNNL project 58745, Work Package AT-15PN230102. This TLR satisfies PNNL’s M3AT-15PN2301027 milestone, and is focused on summarizing the design, development, and evaluation of a two-dimensional matrix phased-array probe referred to as serial number 3 (SN3). In addition, this TLR also provides the results from a performance demonstration of in-sodium target detection trials at 260°C using a one-dimensional 22-element linear array developed in FY14 and referred to as serial number 2 (SN2).

26 CFR 1.381(c)(15)-1 - Indebtedness of certain personal holding companies.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 26 Internal Revenue 4 2010-04-01 2010-04-01 false Indebtedness of certain personal holding companies. 1.381(c)(15)-1 Section 1.381(c)(15)-1 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME TAX (CONTINUED) INCOME TAXES Insolvency Reorganizations § 1.381(c)(15...

Comparative Studies on Microstructure, Mechanical and Pitting Corrosion of Post Weld Heat Treated IN718 Superalloy GTA and EB Welds

NASA Astrophysics Data System (ADS)

Dilkush; Mohammed, Raffi; Madhusudhan Reddy, G.; Srinivasa Rao, K.

2018-03-01

In the present study, an attempt has been made to weld Inconel 718 nickel-base superalloy (IN718 alloy) using gas tungsten arc welding (GTAW) and electron beam welding (EBW) processes. Both the weldments were subjected to post-weld heat treatment condition as follows -980°C / 20 min followed by direct aging condition (DA) as 720°C/8 h/FC followed by 620°C/8 h/AC. The GTA and EB welds of IN718 alloy were compared in two conditions as-received and 980STA conditions. Welds were characterized to observe mechanical properties, pitting corrosion resistance by correlating with observed microstructures. The rate of higher cooling ranges, the fusion zone of EBW exhibited discrete and relative finer lave phases whereas the higher niobium existed laves with coarser structure were observed in GTAW. The significant dissolution of laves were observed at 980STA of EBW. Due to these effects, the EBW of IN718 alloy showed the higher mechanical properties than GTAW. The electrochemical potentiostatic etch test was carried out in 3.5wt% sodium chloride (NaCl) solution to study the pitting corrosion behaviour of the welds. Results of the present investigation established that mechanical properties and pitting corrosion behaviour are significantly better in post weld heat treated condition. The comparative studies showed that the better combination of mechanical properties and pitting corrosion resistance were obtained in 980STA condition of EBW than GTAW.

Edwards nXDS15iC Vacuum Scroll Pump Pressure Testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sessions, H.; Morgan, G. A.

2013-07-17

The SRNL High Pressure Laboratory performed testing on an Edwards Model nXDS15iC Vacuum Scroll Pump on July 10th and 11th of 2013 at 723-A. This testing was done in an attempt to obtain initial compression ratio information for the nXDS15iC pump, with compression ratio defined as discharge pressure of the pump divided by suction pressure. Pressure burst testing was also done on the pump to determine its design pressure for pressure safety reasons. The Edwards nXDS15iC pump is being evaluated by SRNL for use part of the SHINE project being executed by SRNL.

Effect of Heat Treatment on Microstructure and Mechanical Properties of Inconel 625 Alloy Fabricated by Pulsed Plasma Arc Deposition

NASA Astrophysics Data System (ADS)

Xu, Fujia; Lv, Yaohui; Liu, Yuxin; Xu, Binshi; He, Peng

Pulsed plasma arc deposition (PPAD) was successfully used to fabricate the Ni-based superalloy Inconel 625 samples. The effects of three heat treatment technologies on microstructure and mechanical properties of the as-deposited material were investigated. It was found that the as-deposited structure exhibited homogenous cellular dendrite structure, which grew epitaxially along the deposition direction. Moreover, some intermetallic phases including Laves phase and MC carbides were precipitated in the interdendritic region as a result of Nb segregation. Compared with the as-deposited microstructure, the direct aged (DA) microstructure changed little except the precipitation of hardening phases γ' and γ" (Ni3Nb), which enhanced the hardness and tensile strength. But the plastic property was inferior due to the existence of brittle Laves phase. After solution and aging heat treatment (STA), a large amount of Laves particles in the interdendritic regions were dissolved, resulting in the reduction of Nb segregation and the precipitation of needle-like δ (Ni3Nb) in the interdendritic regions and grain boundaries. The hardness and tensile strength were improved without sacrificing the ductility. By homogenization and STA heat treatment (HSTA), Laves particles were dissolved into the matrix completely and resulted in recrystallized large grains with bands of annealing twins. The primary MC particles and remaining phase still appeared in the matrix and grain boundaries. Compared with the as-deposited sample, the mechanical properties decreased severely as a result of the grain growth coarsening. The failure modes of all the tensile specimens were analyzed with fractography.

A dual-phase microstructural approach to damage and fracture of Ti 3SiC 2/SiC joints

DOE PAGES

Nguyen, Ba Nghiep; Henager, Charles H.; Kurtz, Richard J.

2017-12-05

We investigate the microcracking mechanisms responsible for Ti 3SiC 2/SiC joint damage observed at the macroscopic scale after neutron irradiation experiments in detail. A dual-phase microstructural approach to damage and fracture of Ti 3SiC 2/SiC joints is developed that uses a finely discretized two-phase domain based on a digital image of an actual microstructure involving embedded Ti 3SiC 2 and SiC phases. The behaviors of SiC and Ti 3SiC 2 in the domain are described by the continuum damage mechanics (CDM) model reported in Nguyen et al., J. Nucl. Mater., 2017, 495:504–515. This CDM model describes microcracking damage in brittlemore » ceramics caused by thermomechanical loading and irradiation-induced swelling. The dual-phase microstructural model is applied to predict the microcracking mechanisms occurring in a typical Ti 3SiC 2/SiC joint subjected to heating to 800 °C followed by irradiation-induced swelling at this temperature and cooling to room temperature after the applied swelling has reached the maximum swelling levels observed in the experiments for SiC and Ti 3SiC 2. The model predicts minor damage of the joint after heating but significant microcracking in the SiC phase and along the boundaries between SiC and Ti 3SiC 2 as well as along the bonding joint during irradiation-induced swelling and cooling to room temperature. Our predictions qualitatively agree with the limited experimental observations of joint damage at this irradiation temperature.« less

A dual-phase microstructural approach to damage and fracture of Ti 3SiC 2/SiC joints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Ba Nghiep; Henager, Charles H.; Kurtz, Richard J.

We investigate the microcracking mechanisms responsible for Ti 3SiC 2/SiC joint damage observed at the macroscopic scale after neutron irradiation experiments in detail. A dual-phase microstructural approach to damage and fracture of Ti 3SiC 2/SiC joints is developed that uses a finely discretized two-phase domain based on a digital image of an actual microstructure involving embedded Ti 3SiC 2 and SiC phases. The behaviors of SiC and Ti 3SiC 2 in the domain are described by the continuum damage mechanics (CDM) model reported in Nguyen et al., J. Nucl. Mater., 2017, 495:504–515. This CDM model describes microcracking damage in brittlemore » ceramics caused by thermomechanical loading and irradiation-induced swelling. The dual-phase microstructural model is applied to predict the microcracking mechanisms occurring in a typical Ti 3SiC 2/SiC joint subjected to heating to 800 °C followed by irradiation-induced swelling at this temperature and cooling to room temperature after the applied swelling has reached the maximum swelling levels observed in the experiments for SiC and Ti 3SiC 2. The model predicts minor damage of the joint after heating but significant microcracking in the SiC phase and along the boundaries between SiC and Ti 3SiC 2 as well as along the bonding joint during irradiation-induced swelling and cooling to room temperature. Our predictions qualitatively agree with the limited experimental observations of joint damage at this irradiation temperature.« less

A dual-phase microstructural approach to damage and fracture of Ti3SiC2/SiC joints

NASA Astrophysics Data System (ADS)

Nguyen, Ba Nghiep; Henager, Charles H.; Kurtz, Richard J.

2018-02-01

The microcracking mechanisms responsible for Ti3SiC2/SiC joint damage observed at the macroscopic scale after neutron irradiation experiments are investigated in detail. A dual-phase microstructural approach to damage and fracture of Ti3SiC2/SiC joints is developed that uses a finely discretized two-phase domain based on a digital image of an actual microstructure involving embedded Ti3SiC2 and SiC phases. The behaviors of SiC and Ti3SiC2 in the domain are described by the continuum damage mechanics (CDM) model reported in Nguyen et al., J. Nucl. Mater., 2017, 495:504-515. This CDM model describes microcracking damage in brittle ceramics caused by thermomechanical loading and irradiation-induced swelling. The dual-phase microstructural model is applied to predict the microcracking mechanisms occurring in a typical Ti3SiC2/SiC joint subjected to heating to 800 °C followed by irradiation-induced swelling at this temperature and cooling to room temperature after the applied swelling has reached the maximum swelling levels observed in the experiments for SiC and Ti3SiC2. The model predicts minor damage of the joint after heating but significant microcracking in the SiC phase and along the boundaries between SiC and Ti3SiC2 as well as along the bonding joint during irradiation-induced swelling and cooling to room temperature. These predictions qualitatively agree with the limited experimental observations of joint damage at this irradiation temperature.

Simultaneous thermal stability and phase change speed improvement of Sn15Sb85 thin film through erbium doping

NASA Astrophysics Data System (ADS)

Zou, Hua; Zhu, Xiaoqin; Hu, Yifeng; Sui, Yongxing; Sun, Yuemei; Zhang, Jianhao; Zheng, Long; Song, Zhitang

2016-12-01

In general, there is a trade off between the phase change speed and thermal stability in chalcogenide phase change materials, which leads to sacrifice the one in order to ensure the other. For improving the performance, doping is a widely applied technological process. Here, we fabricated Er doped Sn15Sb85 thin films by magnetron sputtering. Compared with the pure Sn15Sb85, we show that Er doped Sn15Sb85 thin films exhibit simultaneous improvement over the thermal stability and the phase change speed. Thus, our results suggest that Er doping provides the opportunity to solve the contradiction. The main reason for improvement of both thermal stability and crystallization speed is due to the existence of Er-Sb and Er-Sn bonds in Er doped Sn15Sb85 films. Hence, Er doped Sn15Sb85 thin films are promising candidates for the phase change memory application, and this method could be extended to other lanthanide-doped phase change materials.

Hot spots of crop production changes at 1.5°C and 2°C

NASA Astrophysics Data System (ADS)

Schleussner, C. F.; Deryng, D.; Mueller, C.; Elliott, J. W.; Saeed, F.; Folberth, C.; Liu, W.; Wang, X.; Pugh, T.

2017-12-01

Studying changes in global and regional crop production is central for assessing the benefits of limiting global average temperature below 1.5ºC versus 2ºC. Projections of future climatic impacts on crop production are commonly focussed on focussing on mean changes. However, substantial risks are posed by extreme weather events such as heat waves and droughts that are of great relevance for imminent policy relevant questions such as price shocks or food security. Preliminary research on the benefits of keeping global average temperature increase below 1.5ºC versus 2ºC above pre-industrial levels has indicated that changes in extreme weather event occurrences will be more pronounced than changes in the mean climate. Here we will present results of crop yield projections for a set of global gridded crop models (GGCMs) for four major staple crops at 1.5°C and 2°C warming above pre-industrial levels using climate forcing data from the Half a degree Additional warming, Prognosis and Projected Impacts (HAPPI) project. We will assess changes in crop production on the global and regional level, and identify hot spots of change. The unique multi-ensemble setup allows to identify changes in extreme yield losses with multi-year to multi-decadal return periods, and thus elucidate the consequences for global and regional food security.

Calorimetric Study of Phase Transitions Involving Twist-Grain-Boundary TGB{A} and TGB{C} Phases

NASA Astrophysics Data System (ADS)

Navailles, L.; Garland, C. W.; Nguyen, H. T.

1996-09-01

High-resolution calorimetry has been used to determine the heat capacity and latent heat associated with phase transitions in the homologous series of chiral liquid crystals nF_2BTFO_1M_7 [ 3-fluoro-4(1-methylheptyloxy)4'-(4''-alkoxy-2'', 3''-difluorobenzoyloxy)tolane] . These compounds exhibit smectic-C^* (SmC^*), twist-grain-boundary (TGBA for n=10, TGBC for n=11, 12) and cholesteric (N^*) phases. All the phase transitions are first order with small to moderate latent heats. There is a large rounded excess heat capacity peak in the N^* phase that is consistent with the predicted appearance of short-range TGB order (chiral line liquid character). This is analogous to the development of an Abrikosov flux vortex liquid in type-II superconductors. Both the n=11 and 12 homologs exhibit two closely spaced transitions in the region where a single TGBC - N^* transition was expected. This suggests the existence of two thermodynamically distinct TGBC phases. Des exprériences de calorimétrie haute résolution ont été réalisées pour déterminer les chaleurs spécifiques et les chaleurs latentes associées aux transitions de phase des homologues de la série crystal liquide nF_2BTFO_1M_7: 3-fluoro-4[1-methyl-heptyloxy]4'-(4''-alcoxy-2'', 3''-difluorobenzoyloxy)tolanes. Ces produits présentent la phase smectique C^* (SmC^*), les phases à torsion par joint de grain (TGBA pour n=10 et TGBC pour n=11, 12) et la phase cholestérique (N^*). Toutes les transitions de phase sont du premier ordre. La chaleur latente associée à ces transitions est faibles ou modérée. Nous observons, dans la phase N^*, un grand pic arrondi qui est en accord avec les prédictions de l'apparition d'un ordre TGB à courte distance (liquide de ligne de dislocation). Ce phénomène est l'analogue du liquide de vortex dans les supraconducteurs de type II. Les composés n=11 et 12 présentent, dans la région où nous attendions une transition TGBC - N^* unique, deux transitions sur un très faible

Consequences of Global Warming of 1.5 °C and 2 °C for Regional Temperature and Precipitation Changes in the Contiguous United States.

PubMed

Karmalkar, Ambarish V; Bradley, Raymond S

2017-01-01

The differential warming of land and ocean leads to many continental regions in the Northern Hemisphere warming at rates higher than the global mean temperature. Adaptation and conservation efforts will, therefore, benefit from understanding regional consequences of limiting the global mean temperature increase to well below 2°C above pre-industrial levels, a limit agreed upon at the United Nations Climate Summit in Paris in December 2015. Here, we analyze climate model simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5) to determine the timing and magnitude of regional temperature and precipitation changes across the contiguous United States (US) for global warming of 1.5 and 2°C and highlight consensus and uncertainties in model projections and their implications for making decisions. The regional warming rates differ considerably across the contiguous US, but all regions are projected to reach 2°C about 10-20 years before the global mean temperature. Although there is uncertainty in the timing of exactly when the 1.5 and 2°C thresholds will be crossed regionally, over 80% of the models project at least 2°C warming by 2050 for all regions for the high emissions scenario. This threshold-based approach also highlights regional variations in the rate of warming across the US. The fastest warming region in the contiguous US is the Northeast, which is projected to warm by 3°C when global warming reaches 2°C. The signal-to-noise ratio calculations indicate that the regional warming estimates remain outside the envelope of uncertainty throughout the twenty-first century, making them potentially useful to planners. The regional precipitation projections for global warming of 1.5°C and 2°C are uncertain, but the eastern US is projected to experience wetter winters and the Great Plains and the Northwest US are projected to experience drier summers in the future. The impact of different scenarios on regional precipitation projections is

WxC-β-SiC Nanocomposite Catalysts Used in Aqueous Phase Hydrogenation of Furfural.

PubMed

Rogowski, Jacek; Andrzejczuk, Mariusz; Berlowska, Joanna; Binczarski, Michal; Kregiel, Dorota; Kubiak, Andrzej; Modelska, Magdalena; Szubiakiewicz, Elzbieta; Stanishevsky, Andrei; Tomaszewska, Jolanta; Witonska, Izabela Alina

2017-11-22

This study investigates the effects of the addition of tungsten on the structure, phase composition, textural properties and activities of β-SiC-based catalysts in the aqueous phase hydrogenation of furfural. Carbothermal reduction of SiO₂ in the presence of WO₃ at 1550 °C in argon resulted in the formation of W x C-β-SiC nanocomposite powders with significant variations in particle morphology and content of W x C-tipped β-SiC nano-whiskers, as revealed by TEM and SEM-EDS. The specific surface area (SSA) of the nanocomposite strongly depended on the amount of tungsten and had a notable impact on its catalytic properties for the production of furfuryl alcohol (FA) and tetrahydrofurfuryl alcohol (THFA). Nanocomposite W x C-β-SiC catalysts with 10 wt % W in the starting mixture had the highest SSA and the smallest W x C crystallites. Some 10 wt % W nanocomposite catalysts demonstrated up to 90% yield of THFA, in particular in the reduction of furfural derived from biomass, although the reproducible performance of such catalysts has yet to be achieved.

17 CFR 240.15c3-2 - Customers' free credit balances.

Code of Federal Regulations, 2011 CFR

2011-04-01

... balances. 240.15c3-2 Section 240.15c3-2 Commodity and Securities Exchanges SECURITIES AND EXCHANGE... Customers' free credit balances. No broker or dealer shall use any funds arising out of any free credit balance carried for the account of any customer in connection with the operation of the business of such...

17 CFR 240.15c3-2 - Customers' free credit balances.

Code of Federal Regulations, 2010 CFR

2010-04-01

... balances. 240.15c3-2 Section 240.15c3-2 Commodity and Securities Exchanges SECURITIES AND EXCHANGE... Customers' free credit balances. No broker or dealer shall use any funds arising out of any free credit balance carried for the account of any customer in connection with the operation of the business of such...

15. Photocopy of photograph (from 'The California Advertiser', c. 1880) ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

15. Photocopy of photograph (from 'The California Advertiser', c. 1880) EXTERIOR, GENERAL VIEW OF MISSION AND CONVENTO, C. 1880 - Mission San Francisco Solano de Sonoma, First & Spain Streets, Sonoma, Sonoma County, CA

Towards the IPCC Special Report on Global Warming of 1.5°C

NASA Astrophysics Data System (ADS)

Masson-Delmotte, Valérie

2017-04-01

signals from climate variability (e.g. changes in water cycle, extremes...), for assessing strengths and limitations of methodologies using high end climate scenarios versus true stabilisation pathways, and for exploring long term risks beyond transient response, with consideration for overshoots and the full timescale of Earth system feedbacks. Lessons learnt from past warm climatic phases may also provide insights complementary to projections, albeit without the perspective of rates of changes that is specific to the issue of 1.5°C global warming. This special report is also designed to be complementary from the other reports in preparation for the IPCC Sixth Assessment cycle (AR6), including the special reports on the ocean and the cryosphere, on land use issues, both scheduled for 2019, and the Working Group main assessment reports, scheduled for 2021-2022.

Simplified procedure for encapsulating cytochrome c in silica aerogel nanoarchitectures while retaining gas-phase bioactivity.

PubMed

Harper-Leatherman, Amanda S; Iftikhar, Mariam; Ndoi, Adela; Scappaticci, Steven J; Lisi, George P; Buzard, Kaitlyn L; Garvey, Elizabeth M

2012-10-16

Cytochrome c (cyt. c) has been encapsulated in silica sol-gels and processed to form bioaerogels with gas-phase activity for nitric oxide through a simplified synthetic procedure. Previous reports demonstrated a need to adsorb cyt. c to metal nanoparticles prior to silica sol-gel encapsulation and processing to form aerogels. We report that cyt. c can be encapsulated in aerogels without added nanoparticles and retain structural stability and gas-phase activity for nitric oxide. While the UV-visible Soret absorbance and nitric oxide response indicate that cyt. c encapsulated with nanoparticles in aerogels remains slightly more stable and functional than cyt. c encapsulated alone, these properties are not very different in the two types of aerogels. From UV-visible and Soret circular dichroism results, we infer that cyt. c encapsulated alone self-organizes to reduce contact with the silica gel in a way that may bear at least some resemblance to the way cyt. c self-organizes into superstructures of protein within aerogels when nanoparticles are present. Both the buffer concentration and the cyt. c concentration of solutions used to synthesize the bioaerogels affect the structural integrity of the protein encapsulated alone within the dried aerogels. Optimized bioaerogels are formed when cyt. c is encapsulated from 40 mM phosphate buffered solutions, and when the loaded cyt. c concentration in the aerogel is in the range of 5 to 15 μM. Increased viability of cyt. c in aerogels is also observed when supercritical fluid used to produce aerogels is vented over relatively long times.

Synthesis of MAX Phases in the Hf-Al-C System.

PubMed

Lapauw, Thomas; Tunca, Bensu; Cabioc'h, Thierry; Lu, Jun; Persson, Per O Å; Lambrinou, Konstantina; Vleugels, Jozef

2016-11-07

For the first time, MAX phases in the Hf-Al-C system were experimentally synthesized using reactive hot pressing. HfC was observed as the main competing phase. The lattice parameters of Hf 2 AlC and Hf 3 AlC 2 were determined by Rietveld refinement based on the X-ray diffraction data. The atomic stacking sequence was revealed by high-resolution scanning transmission electron microscopy. Mixtures of 211 and 312 stacking were observed within the same grain, including 523 layers. This transition in atomic structure is discussed.

Phase change studies in Se85In15-xZnx chalcogenide thin films

NASA Astrophysics Data System (ADS)

Srivastava, Archana; Tiwari, S. N.; Alvi, M. A.; Khan, Shamshad A.

2018-03-01

This research work describes the phase change studies in Se85In15-xZnx thin films at various annealing temperatures. Glassy samples of Se85In15-xZnx were synthesized by the melt quenching method and thin films of thickness 400 nm were prepared by the vacuum evaporation technique on a glass/Si wafer substrate. The glass transition temperature (Tg) and the on-set crystallization temperature (Tc) of the prepared alloys were evaluated by non-isothermal differential scanning calorimetry studies. Thin films were annealed at three temperatures 330 K, 340 K, and 350 K (which are in between Tg and Tc of the synthesized samples) in a vacuum furnace for 2 h. High resolution X-ray diffraction studies demonstrate that the as-prepared films are amorphous in nature whereas the annealed films are of crystalline/polycrystalline in nature. Field emission scanning electron microscopy studies of thin films (as-deposited and crystallized) confirm the phase transformation in Se85In15-xZnx thin films. Optical band gaps were calculated from the Tauc's extrapolation procedure and were found to be enhanced with the Zn concentration and decrease with the increasing annealing temperature. Various optical parameters were evaluated for as-prepared and annealed Se85In15-xZnx thin films. The changes in optical parameters with annealing temperature were described on the basis of structural relaxation as well as changes in defect states and density of localized states during amorphous to crystalline phase transformation in Se85In15-xZnx thin films.

AgMIP Coordinated Global and Regional Assessments for 1.5°C and 2.0°C

NASA Astrophysics Data System (ADS)

Rosenzweig, C.

2017-12-01

The Agricultural Model Intercomparison and Improvement Project (AgMIP) has developed novel methods for Coordinated Global and Regional Assessments (CGRA) of agriculture and food security in a changing world. The present study performs a proof-of-concept of the CGRA to demonstrate advantages and challenges of the framework. This effort responds to the request by UNFCCC for the implications of limiting global temperature increases to 1.5°C and 2.0°C above pre-industrial conditions. The protocols for the 1.5°C/2.0°C assessment establish explicit and testable linkages across disciplines and scales, connecting outputs and inputs from the Shared Socio-economic Pathways (SSPs), Representative Agricultural Pathways (RAPs), HAPPI and CMIP5 ensemble scenarios, global gridded crop models, global agricultural economic models, site-based crop models, and within-country regional economic models. CGRA results show that at the global scale, mixed areas of positive and negative simulated yield changes, with declines in some breadbasket regions led to overall declines in productivity at both 1.5°C and 2.0°C. These projected global yield changes resulted in increases in prices of major commodities in a global economic model. Simulations for 1.5°C and 2.0°C using site-based crop models had mixed results depending on region and crop, but with more negative effects on productivity at 2.0°C than at 1.5°C for the most part. In conjunction with price changes from the global economics models, these productivity declines resulted generally in small positive effects on regional farm livelihoods, showing that farming systems should continue to be viable under high mitigation scenarios. CGRA protocols focus on how mitigation actions and effects differ across scales, with main mechanisms studied in the integrated assessment models being policies and technologies that reduce direct non-CO2 emissions from agriculture, reduce CO2 emissions from land use change and forest sink enhancement

Microstructure/Oxidation/Microhardness Correlations in Gamma-Based and Tau-Based Al-Ti-Cr Alloys

NASA Technical Reports Server (NTRS)

Brady, Michael P.; Smialek, J. L.; Humphrey, D. L.

1994-01-01

The relationships between alloy microstructure and air oxidation kinetics and alloy microstructure and microhardness in the Al-Ti-Cr system for exposures at 800 C and 1000 C were investigated. The relevant phases were identified as tau (Ll2), gamma (LIO), r-Al2Ti, TiCrAl (laves), and Cr2AI. Protective alumina formation was associated with tau, Al-rich TiCrAl, and gamma/TiCrAl mixtures. Brittleness was associated with the TiCrAl phase and tau decomposition to A12Ti + Cr2AI. It was concluded that two-phase gamma + TiCrAl alloys offer the greatest potential for oxidation resistance and room temperature ductility in the Al-Ti-Cr system.

C-terminal peptide extension via gas-phase ion/ion reactions

PubMed Central

Peng, Zhou; McLuckey, Scott A.

2015-01-01

The formation of peptide bonds is of great importance from both a biological standpoint and in routine organic synthesis. Recent work from our group demonstrated the synthesis of peptides in the gas-phase via ion/ion reactions with sulfo-NHS reagents, which resulted in conjugation of individual amino acids or small peptides to the N-terminus of an existing ‘anchor’ peptide. Here, we demonstrate a complementary approach resulting in the C-terminal extension of peptides. Individual amino acids or short peptides can be prepared as reagents by incorporating gas phase-labile protecting groups to the reactive C-terminus and then converting the N-terminal amino groups to the active ketenimine reagent. Gas-phase ion/ion reactions between the anionic reagents and doubly protonated “anchor” peptide cations results in extension of the “anchor” peptide with new amide bond formation at the C-terminus. We have demonstrated that ion/ion reactions can be used as a fast, controlled, and efficient means for C-terminal peptide extension in the gas phase. PMID:26640400

Jaridonin-induced G2/M phase arrest in human esophageal cancer cells is caused by reactive oxygen species-dependent Cdc2-tyr15 phosphorylation via ATM–Chk1/2–Cdc25C pathway

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Yong-Cheng; Su, Nan; Shi, Xiao-Jing

2015-01-15

Jaridonin, a novel diterpenoid from Isodon rubescens, has been shown previously to inhibit proliferation of esophageal squamous cancer cells (ESCC) through G2/M phase cell cycle arrest. However, the involved mechanism is not fully understood. In this study, we found that the cell cycle arrest by Jaridonin was associated with the increased expression of phosphorylation of ATM at Ser1981 and Cdc2 at Tyr15. Jaridonin also resulted in enhanced phosphorylation of Cdc25C via the activation of checkpoint kinases Chk1 and Chk2, as well as in increased phospho-H2A.X (Ser139), which is known to be phosphorylated by ATM in response to DNA damage. Furthermore,more » Jaridonin-mediated alterations in cell cycle arrest were significantly attenuated in the presence of NAC, implicating the involvement of ROS in Jaridonin's effects. On the other hand, addition of ATM inhibitors reversed Jaridonin-related activation of ATM and Chk1/2 as well as phosphorylation of Cdc25C, Cdc2 and H2A.X and G2/M phase arrest. In conclusion, these findings identified that Jaridonin-induced cell cycle arrest in human esophageal cancer cells is associated with ROS-mediated activation of ATM–Chk1/2–Cdc25C pathway. - Highlights: • Jaridonin induced G2/M phase arrest through induction of redox imbalance. • Jaridonin increased the level of ROS through depleting glutathione in cell. • ATM–Chk1/2–Cdc25C were involved in Jaridonin-induced cell cycle arrest. • Jaridonin selectively inhibited cancer cell viability and cell cycle progression.« less

Thermomechanical testing of high-temperature composites - Thermomechanical fatigue (TMF) behavior of SiC(SCS-6)/Ti-15-3

NASA Technical Reports Server (NTRS)

Castelli, Michael G.; Bartolotta, Paul; Ellis, John R.

1992-01-01

Thermomechanical testing techniques recently developed for monolithic structural alloys were successfully extended to continuous fiber reinforced composite materials in plate form. The success of this adaptation was verified on a model metal matrix composite (MMC) material, namely SiC(SCS-6)/Ti-15V-3Cr-3Al-3Sn. Effects of heating system type and specimen preparation are also addressed. Cyclic lives determined under full thermomechanical conditions were shown to be significantly reduced from those obtained under comparable isothermal and in-phase bi-thermal conditions. Fractography and metallography from specimens subjected to isothermal, out-of-phase and in-phase conditions reveal distinct differences in damage-failure modes. Isothermal metallography revealed extensive matrix cracking associated with fiber damage throughout the entire cross-section of the specimen. Out-of-phase metallography revealed extensive matrix damage associated with minimal (if any) fiber cracking. However, the damage was located exclusively at surface and near-surface locations. In-phase conditions produced extensive fiber cracking throughout the entire cross-section, associated with minimal (if any) matrix damage.

Effect of Long-Term Service on Microstructure and Mechanical Properties of Martensitic 9% Cr Steel

NASA Astrophysics Data System (ADS)

Golański, Grzegorz; Zielińska-Lipiec, Anna; Zieliński, Adam; Sroka, Marek

2017-03-01

The paper presents the results of research on the X10CrMoVNbN9-1 (T91) steel after long-term service. The material for testing was taken from a pipe section of a boiler superheater coil serviced for around 105,000 h at the temperature of 540 °C, at the pressure of 12.5 MPa. A quantitative analysis including the measurement of mean diameter of subgrains and precipitates as well as the density of dislocations of the examined steel was performed by means of TEM. The microscopic tests of T91 steel were complemented with the results of tests on mechanical properties which included also the short creep tests. After service, the investigated steel was characterized by a retained lath microstructure of tempered martensite with fine subgrain and quite large density of dislocations as well as numerous precipitates. In the microstructure, apart from the particles of M23C6 and MX (VX, NbC, V-wings), the precipitates of Laves phase and single particles of Z phase were revealed. It has been shown that the extent of degradation of the T91 steel microstructure was minor, which resulted from its low temperature of service. Performed tests of mechanical properties showed that these properties fulfilled the minimum requirements for this steel in the as-received condition. A favorable influence of fine precipitates of Laves phase on mechanical properties was observed. Moreover, an insignificant influence of single precipitates of Z phase on the creep resistance of the examined steel was stated.

Solid-liquid phase equilibria in the ternary system (LiBO2 + Li2CO3 + H2O) at 288.15 and 298.15 K

NASA Astrophysics Data System (ADS)

Wang, Shi-qiang; Guo, Ya-fei; Yang, Jian-sen; Deng, Tian-long

2015-12-01

Experimental studies on the solubilities and physicochemical properties including density, refractive index and pH value in the ternary systems (LiBO2 + Li2CO3 + H2O) at 288.15 and 298.15 K were determined with the method of isothermal dissolution equilibrium. Based on the experimental results, the phase diagrams and their corresponding physicochemical properties versus composition diagram in the system were plotted. In the phase diagrams of the ternary system at 288.15 and 298.15 K, there are one eutectic point and two crystallization regions corresponding to lithium metaborate octahydrate (LiBO2 · 8H2O) and lithium carbonate (Li2CO3), respectively. This system at both temperatures belongs to hydrate type I, and neither double salt nor solid solution was found. A comparison of the phase diagrams for this ternary system at 288.15 and 298.15 K shows that the solid phase numbers and exist minerals are the same, and the area of crystallization region of Li2CO3 is increased obviously with the increasing temperature while that of LiBO2 · 8H2O is decreased. The physicochemical properties (density, pH value and refractive index) of the solutions of the ternary system at two temperatures changes regularly with the increasing lithium carbonate concentration. The calculated values of density and refractive index using empirical equations of the ternary system are in good agreement with the experimental values.

17 CFR 240.15c3-1a - Options (Appendix A to 17 CFR 240.15c3-1).

Code of Federal Regulations, 2014 CFR

2014-04-01

... Regulations Under the Securities Exchange Act of 1934 Rules Relating to Over-The-Counter Markets § 240.15c3-1a... from an assumed movement (both up and down) in the current market value of the underlying instrument...) The term major market foreign currency shall mean the currency of a sovereign nation whose short-term...

Impacts on terrestrial biodiversity of moving from a 2°C to a 1.5°C target

NASA Astrophysics Data System (ADS)

Smith, Pete; Price, Jeff; Molotoks, Amy; Warren, Rachel; Malhi, Yadvinder

2018-05-01

We applied a recently developed tool to examine the reduction in climate risk to biodiversity in moving from a 2°C to a 1.5°C target. We then reviewed the recent literature examining the impact of (a) land-based mitigation options and (b) land-based greenhouse gas removal options on biodiversity. We show that holding warming to 1.5°C versus 2°C can significantly reduce the number of species facing a potential loss of 50% of their climatic range. Further, there would be an increase of 5.5-14% of the globe that could potentially act as climatic refugia for plants and animals, an area equivalent to the current global protected area network. Efforts to meet the 1.5°C target through mitigation could largely be consistent with biodiversity protection/enhancement. For impacts of land-based greenhouse gas removal technologies on biodiversity, some (e.g. soil carbon sequestration) could be neutral or positive, others (e.g. bioenergy with carbon capture and storage) are likely to lead to conflicts, while still others (e.g. afforestation/reforestation) are context-specific, when applied at scales necessary for meaningful greenhouse gas removal. Additional effort to meet the 1.5°C target presents some risks, particularly if inappropriately managed, but it also presents opportunities. This article is part of the theme issue `The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'.

17 CFR 240.15c1-8 - Sales at the market.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Sales at the market. 240.15c1... Securities Exchange Act of 1934 Rules Relating to Over-The-Counter Markets § 240.15c1-8 Sales at the market... securities exchange that such security is being offered to such customer “at the market” or at a price...

Development of a Novel, Bicombinatorial Approach to Alloy Development, and Application to Rapid Screening of Creep Resistant Titanium Alloys

NASA Astrophysics Data System (ADS)

Martin, Brian

Combinatorial approaches have proven useful for rapid alloy fabrication and optimization. A new method of producing controlled isothermal gradients using the Gleeble Thermomechanical simulator has been developed, and demonstrated on the metastable beta-Ti alloy beta-21S, achieving a thermal gradient of 525-700 °C. This thermal gradient method has subsequently been coupled with existing combinatorial methods of producing composition gradients using the LENS(TM) additive manufacturing system, through the use of elemental blended powders. This has been demonstrated with a binary Ti-(0-15) wt% Cr build, which has subsequently been characterized with optical and electron microscopy, with special attention to the precipitate of TiCr2 Laves phases. The TiCr2 phase has been explored for its high temperature mechanical properties in a new oxidation resistant beta-Ti alloy, which serves as a demonstration of the new bicombinatorial methods developed as applied to a multicomponent alloy system.

Neutron capture cross section of {sup 14}C of astrophysical interest studied by Coulomb breakup of {sup 15}C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakamura, T.; Fukuda, N.; Aoi, N.

2009-03-15

The neutron capture reaction on {sup 14}C leading to the {sup 15}C ground state, which plays an important role in various nucleosynthesis processes, has been studied using the Coulomb breakup of {sup 15}C on a Pb target at 68 MeV/nucleon. The breakup cross section has been converted into the energy-dependent neutron capture cross section using the principle of detailed balance. The energy spectrum shows typical p-wave neutron capture characteristics, which is explained by the fact that the ground state of {sup 15}C possesses a strong single-particle s-wave component and a moderate-sized neutron halo structure. The capture cross section for themore » {sup 14}C(n,{gamma}){sup 15}C reaction derived from the present experiment has been found to be consistent with the most recent data, directly measured using a {sup 14}C target. This result assures the validity of the Coulomb breakup method in deriving the neutron capture cross section for neutron-rich nuclei.« less

Socioeconomic Implications of Achieving 2.0 °C and 1.5 °C Climate Targets under Scientific Uncertainties

NASA Astrophysics Data System (ADS)

Su, X.; Takahashi, K.; Fujimori, S.; Hasegawa, T.; Tanaka, K.; Shiogama, H.; Emori, S.; LIU, J.; Hanasaki, N.; Hijioka, Y.; Masui, T.

2017-12-01

Large uncertainty exists in the temperature projections, including contributions from carbon cycle, climate system and aerosols. For the integrated assessment models (IAMs), like DICE, FUND and PAGE, however, the scientific uncertainties mainly rely on the distribution of (equilibrium) climate sensitivity. This study aims at evaluating the emission pathways by limiting temperature increase below 2.0 ºC or 1.5 ºC after 2100 considering scientific uncertainties, and exploring how socioeconomic indicators are affected by such scientific uncertainties. We use a stochastic version of the SCM4OPT, with an uncertainty measurement by considering alternative ranges of key parameters. Three climate cases, namely, i) base case of SSP2, ii) limiting temperature increase below 2.0 ºC after 2100 and iii) limiting temperature increase below 1.5 ºC after 2100, and three types of probabilities - i) >66% probability or likely, ii) >50% probability or more likely than not and iii) the mean of the probability distribution, are considered in the study. The results show that, i) for the 2.0ºC case, the likely CO2 reduction rate in 2100 ranges from 75.5%-102.4%, with mean value of 88.1%, and 93.0%-113.1% (mean 102.5%) for the 1.5ºC case; ii) a likely range of forcing effect is found for the 2.0 ºC case (2.7-3.9 Wm-2) due to scientific uncertainty, and 1.9-3.1 Wm-2 for the 1.5 ºC case; iii) the carbon prices within 50% confidential interval may differ a factor of 3 for both the 2.0ºC case and the 1.5 ºC case; iv) the abatement costs within 50% confidential interval may differ a factor of 4 for both the 2.0ºC case and the 1.5 ºC case. Nine C4MIP carbon cycle models and nineteen CMIP3 AOGCMs are used to account for the scientific uncertainties, following MAGICC 6.0. These uncertainties will result in a likely radiative forcing range of 6.1-7.5 Wm-2 and a likely temperature increase of 3.1-4.5 ºC in 2100 for the base case of SSP2. If we evaluate the 2 ºC target by limiting the

Experimental and theoretical characterization of ordered MAX phases Mo{sub 2}TiAlC{sub 2} and Mo{sub 2}Ti{sub 2}AlC{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anasori, Babak; A.J. Drexel Nanomaterials Institute, Drexel University, Philadelphia, Pennsylvania 19104; Dahlqvist, Martin

2015-09-07

Herein, we report on the phase stabilities and crystal structures of two newly discovered ordered, quaternary MAX phases—Mo{sub 2}TiAlC{sub 2} and Mo{sub 2}Ti{sub 2}AlC{sub 3}—synthesized by mixing and heating different elemental powder mixtures of mMo:(3-m)Ti:1.1Al:2C with 1.5 ≤ m ≤ 2.2 and 2Mo: 2Ti:1.1Al:2.7C to 1600 °C for 4 h under Ar flow. In general, for m ≥ 2 an ordered 312 phase, (Mo{sub 2}Ti)AlC{sub 2}, was the majority phase; for m < 2, an ordered 413 phase (Mo{sub 2}Ti{sub 2})AlC{sub 3}, was the major product. The actual chemistries determined from X-ray photoelectron spectroscopy (XPS) are Mo{sub 2}TiAlC{sub 1.7} and Mo{sub 2}Ti{sub 1.9}Al{sub 0.9}C{sub 2.5}, respectively. High resolution scanning transmissionmore » microscopy, XPS and Rietveld analysis of powder X-ray diffraction confirmed the general ordered stacking sequence to be Mo-Ti-Mo-Al-Mo-Ti-Mo for Mo{sub 2}TiAlC{sub 2} and Mo-Ti-Ti-Mo-Al-Mo-Ti-Ti-Mo for Mo{sub 2}Ti{sub 2}AlC{sub 3}, with the carbon atoms occupying the octahedral sites between the transition metal layers. Consistent with the experimental results, the theoretical calculations clearly show that M layer ordering is mostly driven by the high penalty paid in energy by having the Mo atoms surrounded by C in a face-centered configuration, i.e., in the center of the M{sub n+1}X{sub n} blocks. At 331 GPa and 367 GPa, respectively, the Young's moduli of the ordered Mo{sub 2}TiAlC{sub 2} and Mo{sub 2}Ti{sub 2}AlC{sub 3} are predicted to be higher than those calculated for their ternary end members. Like most other MAX phases, because of the high density of states at the Fermi level, the resistivity measurement over 300 to 10 K for both phases showed metallic behavior.« less

Effects of climate on deer bone δ15N and δ13C: Lack of precipitation effects on δ15N for animals consuming low amounts of C 4 plants

NASA Astrophysics Data System (ADS)

Cormie, A. B.; Schwarcz, H. P.

1996-11-01

We have examined the relationship of bone collagen δ15N and δ13C to climatic variables, humidity, temperature, and amount of precipitation using fifty-nine specimens of North American white-tailed deer ( Odocoileus virginianus) from forty-six different locations. In previous studies of African mammals there was a significant correlation between bone collagen δ15N and local amount of precipitation. Results presented here similarly show an increase in δ15N with decreasing amount of precipitation but only for 25% of the animals, namely those consuming more than 10% C 4 plants. These animals also exhibited a significant correlation between δ13C and temperature which mirrors previous observations for grasses suggesting that these deer consume grasses during times of population and nutrient stress. In contrast, even in dry areas containing high proportions of C 4 grasses, the majority of the deer had consumed low amounts of C 4 plants and these deer did not have δ15N which correlate with amount of precipitation. Only when deer deviated from their normal feeding pattern by consuming C 4 plants or grasses did their δ15N correlate with amount of rainfall. For these animals, consumption of C 4 plants or grasses may signal conditions of water and nutrient stress. An increase in δ15N of bone collagen may result from combined effects from excretion of concentrated urine (to conserve water) and increased internal recycling of nitrogen (to conserve nitrogen).

Rp-cAMPS Prodrugs Reveal the cAMP Dependence of First-Phase Glucose-Stimulated Insulin Secretion

PubMed Central

Schwede, Frank; Chepurny, Oleg G.; Kaufholz, Melanie; Bertinetti, Daniela; Leech, Colin A.; Cabrera, Over; Zhu, Yingmin; Mei, Fang; Cheng, Xiaodong; Manning Fox, Jocelyn E.; MacDonald, Patrick E.; Genieser, Hans-G.; Herberg, Friedrich W.

2015-01-01

cAMP-elevating agents such as the incretin hormone glucagon-like peptide-1 potentiate glucose-stimulated insulin secretion (GSIS) from pancreatic β-cells. However, a debate has existed since the 1970s concerning whether or not cAMP signaling is essential for glucose alone to stimulate insulin secretion. Here, we report that the first-phase kinetic component of GSIS is cAMP-dependent, as revealed through the use of a novel highly membrane permeable para-acetoxybenzyl (pAB) ester prodrug that is a bioactivatable derivative of the cAMP antagonist adenosine-3′,5′-cyclic monophosphorothioate, Rp-isomer (Rp-cAMPS). In dynamic perifusion assays of human or rat islets, a step-wise increase of glucose concentration leads to biphasic insulin secretion, and under these conditions, 8-bromoadenosine-3′,5′-cyclic monophosphorothioate, Rp-isomer, 4-acetoxybenzyl ester (Rp-8-Br-cAMPS-pAB) inhibits first-phase GSIS by up to 80%. Surprisingly, second-phase GSIS is inhibited to a much smaller extent (≤20%). Using luciferase, fluorescence resonance energy transfer, and bioluminescence resonance energy transfer assays performed in living cells, we validate that Rp-8-Br-cAMPS-pAB does in fact block cAMP-dependent protein kinase activation. Novel effects of Rp-8-Br-cAMPS-pAB to block the activation of cAMP-regulated guanine nucleotide exchange factors (Epac1, Epac2) are also validated using genetically encoded Epac biosensors, and are independently confirmed in an in vitro Rap1 activation assay using Rp-cAMPS and Rp-8-Br-cAMPS. Thus, in addition to revealing the cAMP dependence of first-phase GSIS from human and rat islets, these findings establish a pAB-based chemistry for the synthesis of highly membrane permeable prodrug derivatives of Rp-cAMPS that act with micromolar or even nanomolar potency to inhibit cAMP signaling in living cells. PMID:26061564

Impact Toughness of 0.2 Pct C-1.5 Pct Si-(1.5 to 5) Pct Mn Transformation-Induced Plasticity-Aided Steels with an Annealed Martensite Matrix

NASA Astrophysics Data System (ADS)

Tanino, Hikaru; Horita, Masaomi; Sugimoto, Koh-Ichi

2016-05-01

The impact properties of 0.2 pct C-1.5 pct Si-(1.5 to 5) pct Mn transformation-induced plasticity (TRIP)-aided steels with an annealed martensite matrix which had been subjected to isothermal transformation after inter-critical annealing were investigated for potential automotive applications. The impact properties are related to the retained austenite characteristics of the steels. The products of tensile strength (TS) and Charpy impact absorbed value (CIAV) were the same for the 1.5 and 5 pct Mn steels, although the ductile-brittle transition temperature was higher for the latter. The impact properties of the 3 pct Mn steel were worse than these two steels. The high TS × CIAV value for the 5 pct Mn steel at 293 K (25 °C) was mainly caused by the TRIP effect of a larger amount of retained austenite (36 vol pct) and the hardened matrix structure; low retained austenite stability and/or a hard martensite-austenite phase reduced this value. The higher ductile-brittle transition temperature of the 5 pct Mn steel was associated with Mn segregation, a large amount of unstable retained austenite on prior austenitic grain boundaries, and decreased cleavage fracture stress owing to the high Mn content.

Impacts on terrestrial biodiversity of moving from a 2°C to a 1.5°C target.

PubMed

Smith, Pete; Price, Jeff; Molotoks, Amy; Warren, Rachel; Malhi, Yadvinder

2018-05-13

We applied a recently developed tool to examine the reduction in climate risk to biodiversity in moving from a 2°C to a 1.5°C target. We then reviewed the recent literature examining the impact of (a) land-based mitigation options and (b) land-based greenhouse gas removal options on biodiversity. We show that holding warming to 1.5°C versus 2°C can significantly reduce the number of species facing a potential loss of 50% of their climatic range. Further, there would be an increase of 5.5-14% of the globe that could potentially act as climatic refugia for plants and animals, an area equivalent to the current global protected area network. Efforts to meet the 1.5°C target through mitigation could largely be consistent with biodiversity protection/enhancement. For impacts of land-based greenhouse gas removal technologies on biodiversity, some (e.g. soil carbon sequestration) could be neutral or positive, others (e.g. bioenergy with carbon capture and storage) are likely to lead to conflicts, while still others (e.g. afforestation/reforestation) are context-specific, when applied at scales necessary for meaningful greenhouse gas removal. Additional effort to meet the 1.5°C target presents some risks, particularly if inappropriately managed, but it also presents opportunities.This article is part of the theme issue 'The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'. © 2018 The Authors.

Impacts on terrestrial biodiversity of moving from a 2°C to a 1.5°C target

PubMed Central

Price, Jeff; Molotoks, Amy; Warren, Rachel

2018-01-01

We applied a recently developed tool to examine the reduction in climate risk to biodiversity in moving from a 2°C to a 1.5°C target. We then reviewed the recent literature examining the impact of (a) land-based mitigation options and (b) land-based greenhouse gas removal options on biodiversity. We show that holding warming to 1.5°C versus 2°C can significantly reduce the number of species facing a potential loss of 50% of their climatic range. Further, there would be an increase of 5.5–14% of the globe that could potentially act as climatic refugia for plants and animals, an area equivalent to the current global protected area network. Efforts to meet the 1.5°C target through mitigation could largely be consistent with biodiversity protection/enhancement. For impacts of land-based greenhouse gas removal technologies on biodiversity, some (e.g. soil carbon sequestration) could be neutral or positive, others (e.g. bioenergy with carbon capture and storage) are likely to lead to conflicts, while still others (e.g. afforestation/reforestation) are context-specific, when applied at scales necessary for meaningful greenhouse gas removal. Additional effort to meet the 1.5°C target presents some risks, particularly if inappropriately managed, but it also presents opportunities. This article is part of the theme issue ‘The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'. PMID:29610386

Effect of disruption of actin filaments by Clostridium botulinum C2 toxin on insulin secretion in HIT-T15 cells and pancreatic islets.

PubMed Central

Li, G; Rungger-Brändle, E; Just, I; Jonas, J C; Aktories, K; Wollheim, C B

1994-01-01

To examine their role in insulin secretion, actin filaments (AFs) were disrupted by Clostridium botulinum C2 toxin that ADP-ribosylates G-actin. Ribosylation also prevents polymerization of G-actin to F-actin and inhibits AF assembly by capping the fast-growing end of F-actin. Pretreatment of HIT-T15 cells with the toxin inhibited stimulated insulin secretion in a time- and dose-dependent manner. The toxin did not affect cellular insulin content or nonstimulated secretion. In static incubation, toxin treatment caused 45-50% inhibition of secretion induced by nutrients alone (10 mM glucose + 5 mM glutamine + 5 mM leucine) or combined with bombesin (phospholipase C-activator) and 20% reduction of that potentiated by forskolin (stimulator of adenylyl cyclase). In perifusion, the stimulated secretion during the first phase was marginally diminished, whereas the second phase was inhibited by approximately 80%. Pretreatment of HIT cells with wartmannin, a myosin light chain kinase inhibitor, caused a similar pattern of inhibition of the biphasic insulin release as C2 toxin. Nutrient metabolism and bombesin-evoked rise in cytosolic free Ca2+ were not affected by C2 toxin, indicating that nutrient recognition and the coupling between receptor activation and second messenger generation was not changed. In the toxin-treated cells, the AF web beneath the plasma membrane and the diffuse cytoplasmic F-actin fibers disappeared, as shown both by staining with an antibody against G- and F-actin and by staining F-actin with fluorescent phallacidin. C2 toxin dose-dependently reduced cellular F-actin content. Stimulation of insulin secretion was not associated with changes in F-actin content and organization. Treatment of cells with cytochalasin E and B, which shorten AFs, inhibited the stimulated insulin release by 30-50% although differing in their effects on F-actin content. In contrast to HIT-T15 cells, insulin secretion was potentiated in isolated rat islets after disruption of

Gas-phase Absorption of {{\\rm{C}}}_{70}^{2+} below 10 K: Astronomical Implications

NASA Astrophysics Data System (ADS)

Campbell, E. K.; Holz, M.; Maier, J. P.

2017-02-01

The electronic spectrum of the fullerene dication {{{C}}}702+ has been measured in the gas phase at low temperature in a cryogenic radiofrequency ion trap. The spectrum consists of a strong origin band at 7030 Å and two weaker features to higher energy. The bands have FWHMs of 35 Å indicating an excited state lifetime on the order of one-tenth of a picosecond. Absorption cross-section measurements yield (2 ± 1) × 10-15 cm2 at 7030 Å. These results are used to predict the depth of diffuse interstellar bands (DIBs) due to the absorption by {{{C}}}702+. At an assumed column density of 2 × 1012 cm-2 the attenuation of starlight at 7030 Å is around 0.4% and thus the detection of such a shallow and broad interstellar band would be difficult. The electronic spectrum of {{{C}}}602+ shows no absorptions in the visible. Below 4000 Å the spectra of C60, {{{C}}}60+ and {{{C}}}602+ are similar. The large intrinsic FWHM of the features in this region, ˜200 Å for the band near 3250 Å, make them unsuitable for DIB detection.

Phase Transformation and Creep of Mg-Al-Ca Based Die-Cast Alloys

NASA Astrophysics Data System (ADS)

Suzuki, Akane; Saddock, Nicholas D.; Jones, J. Wayne; Pollock, Tresa M.

The microstructure and microstructural stability of die-cast AC53 (Mg-5Al-3Ca) and AXJ530 (Mg-5Al-3Ca-0.15Sr) have been investigated in detail by transmission electron microscopy (TEM). Both alloys have an as-cast microstructure of α-Mg with (Mg, Al)2Ca (dihexagonal C36) eutectic at grain boundaries. During aging at 573 K, the C36 phase transforms to Al2Ca (cubic Cl5) phase. These two phases have a crystallographic orientation relationship of (0001)C36//{111}C15 and [2110]C36//[011]C15, and the transformation from C36 to C15 occurs by a shear-assisted process. Despite this change in the phase constitution, the network structure of the intermetallic compound(s) surrounding α-Mg grains is fairly stable, morphologically, even after prolonged exposure at elevated temperature. In the α-Mg matrix phase, precipitation of Al2Ca was observed after aging for 360 ks at 573 K. The precipitates are disc-shaped with a habit plane of {111}C15//(0001)α. AXJ530 shows higher creep resistance than AC53. The dislocation substructure that evolved during creep deformation was investigated in both alloys, and the basal and non-basal slip of a-dislocation and other slip modes of a+c- dislocations were observed. The relationship between creep properties and microstructure is discussed.

Reduced probability of ice-free summers for 1.5 °C compared to 2 °C warming

NASA Astrophysics Data System (ADS)

Jahn, Alexandra

2018-05-01

Arctic sea ice has declined rapidly with increasing global temperatures. However, it is largely unknown how Arctic summer sea-ice impacts would vary under the 1.5 °C Paris target compared to scenarios with greater warming. Using the Community Earth System Model, I show that constraining warming to 1.5 °C rather than 2.0 °C reduces the probability of any summer ice-free conditions by 2100 from 100% to 30%. It also reduces the late-century probability of an ice cover below the 2012 record minimum from 98% to 55%. For warming above 2 °C, frequent ice-free conditions can be expected, potentially for several months per year. Although sea-ice loss is generally reversible for decreasing temperatures, sea ice will only recover to current conditions if atmospheric CO2 is reduced below present-day concentrations. Due to model biases, these results provide a lower bound on summer sea-ice impacts, but clearly demonstrate the benefits of constraining warming to 1.5 °C.

Optical and near-infrared study of the Ca-rich transient iPTF15eqv in the early phase

NASA Astrophysics Data System (ADS)

Kawahara, Naoki; Yamanaka, Masayuki; Kawabata, Koji; Nakaoka, Tatsuya; Kawabata, Miho; Maeda, Keiichi; Takaki, Katsutoshi; Akitaya, Hiroshi; Itoh, Ryosuke; Moritani, Yuki; Uemura, Makoto; Yoshida, Michitoshi

2018-01-01

Supernovae (SNe) exhibiting strong calcium features in their spectra are called Ca-rich transients. Frequently their early-phase spectra also exhibit helium absorption lines. They are mostly discovered in elliptical galaxies or at a remote location far from the host galaxy center. Well-observed samples are still too limited to clarify the explosion and progenitor properties. We present optical and near-infrared observations of a Ca-rich transient iPTF15eqv in the spiral galaxy NGC 3430. The data are obtained using 1.5-m Kanata telescope since Sep 28, 2015. While the discovery was at a post-maximum-phase, we infer the maximum date to be 30 days before the discovery date, by comparing its light curve and spectroscopic evolution to those of well-observed samples. The spectra exhibit absorption lines of He I and prominent emission lines of Ca II IR and [Ca II] from +31 to 69 d after the maximum date. We find that iPTF15eqv is more luminous than other Ca-rich transients by 1.5 to 2 mag on +31 d, and we estimate that the peak absolute magnitude in the R band is approximately -18 to -16.5 mag. The decline rate of the light curve between 30 and 60 d is similar to those of SNe Ib/c. The line velocity of the helium is similar to those of Ca-rich transients but also to SNe Ib. The ejecta properties inferred from our observations indicate that iPTF15eqv has a larger nickel mass than typical Ca-rich transients. While these properties show similarity to SNe Ib, we show that most of these properties are indeed shared by other Ca-rich transients. The properties of iPTF15eqv may thus still be regarded to be within the diversities among the Ca-rich transients.

Fabrication and characterization of W/B4C lamellar multilayer grating and NbC/Si multilayer phase-shift reflector

NASA Astrophysics Data System (ADS)

Pradhan, P. C.; Bhartiya, S.; Singh, A.; Majhi, A.; Gome, A.; Dhawan, R.; Nayak, M.; Sahoo, P. K.; Rai, S. K.; Reddy, V. R.

2017-08-01

We present fabrication and structural analysis of two different multilayer grating structures. W/B4C based lamellar multilayer grating (LMG) was studied for high resolution monochomator application near soft x-ray region ( 1.5 keV). Whereas NbC/Si based multilayer phase-shift reflector (MPR) was studied for high reflection at normal incidence near Si L-edge ( 99 eV) and simultaneously to suppress the unwanted vacuum ultraviolet / infrared radiation. The grating patterns of different periods down to D = 10 micron were fabricated on Si substrates by using photolithography, and multilayers (MLs) of different periodicity (d = 10 to 2 nm) and number of layer pairs (15 to 100) were coated using sputtering techniques by optimizing the process parameters. The LMG and MPR samples are characterized by x-ray reflectivity (XRR) and atomic force microscopy (AFM) measurements. XRR results show successive higher order Bragg peaks that reveal a well-defined vertical periodic structure in LMG, MPR and ML structures. The lateral periodicity of the grating and depth of the rectangular groves were analyzed using AFM. The AFM results show good quality of lateral periodic structures in terms of groove profile. The effect of the process parameters on the microstructure (both on vertical and lateral patterns) of ML, LMG and MPR were analyzed.

Consequences of Global Warming of 1.5 °C and 2 °C for Regional Temperature and Precipitation Changes in the Contiguous United States

PubMed Central

Bradley, Raymond S.

2017-01-01

The differential warming of land and ocean leads to many continental regions in the Northern Hemisphere warming at rates higher than the global mean temperature. Adaptation and conservation efforts will, therefore, benefit from understanding regional consequences of limiting the global mean temperature increase to well below 2°C above pre-industrial levels, a limit agreed upon at the United Nations Climate Summit in Paris in December 2015. Here, we analyze climate model simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5) to determine the timing and magnitude of regional temperature and precipitation changes across the contiguous United States (US) for global warming of 1.5 and 2°C and highlight consensus and uncertainties in model projections and their implications for making decisions. The regional warming rates differ considerably across the contiguous US, but all regions are projected to reach 2°C about 10-20 years before the global mean temperature. Although there is uncertainty in the timing of exactly when the 1.5 and 2°C thresholds will be crossed regionally, over 80% of the models project at least 2°C warming by 2050 for all regions for the high emissions scenario. This threshold-based approach also highlights regional variations in the rate of warming across the US. The fastest warming region in the contiguous US is the Northeast, which is projected to warm by 3°C when global warming reaches 2°C. The signal-to-noise ratio calculations indicate that the regional warming estimates remain outside the envelope of uncertainty throughout the twenty-first century, making them potentially useful to planners. The regional precipitation projections for global warming of 1.5°C and 2°C are uncertain, but the eastern US is projected to experience wetter winters and the Great Plains and the Northwest US are projected to experience drier summers in the future. The impact of different scenarios on regional precipitation projections is

On the synthesis of AlPO4-21 molecular sieve by vapor phase transport method and its phase transformation to AlPO4-15 molecular sieve

NASA Astrophysics Data System (ADS)

Shao, Hui; Chen, Jingjing; Chen, Xia; Leng, Yixin; Zhong, Jing

2015-04-01

An experimental design was applied to the synthesis of AlPO4-21 molecular sieve (AWO structure) by vapor phase transport (VPT) method, using tetramethylguanidine (TMG) as the template. In this study, the effects of crystallization time, crystallization temperature, phosphor content, template content and water content in the synthesis gel were investigated. The materials obtained were characterized by X-ray diffraction, scanning electron microscopy and fourier transform infrared spectroscopy (FT-IR). Microstructural analysis of the crystal growth in vapor synthetic conditions revealed a revised crystal growth route from zeolite AlPO4-21 to AlPO4-15 in the presence of the TMG. Homogenous hexagonal prism AlPO4-21 crystals with size of 7 × 3 μm were synthesized at a lower temperature (120 °C), which were completely different from the typical tabular parallelogram crystallization microstructure of AlPO4-21 phase. The crystals were transformed into AlPO4-21 phase with higher crystallization temperature, longer crystallization time, higher P2O5/Al2O3 ratio and higher TMG/Al2O3 ratio.

75 FR 13238 - Special Conditions: McCauley Propeller Systems, Model Propeller 3D15C1401/C80MWX-X

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-19

...-X AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed special conditions... for McCauley Propeller Systems for model propeller 3D15C1401/C80MWX-X. We are withdrawing the notice... McCauley Propeller Systems for model propeller 3D15C1401/C80MWX-X (71 FR 43674). On November 29, 2004...

Uncertain impacts on economic growth when stabilizing global temperatures at 1.5°C or 2°C warming

NASA Astrophysics Data System (ADS)

Pretis, Felix; Schwarz, Moritz; Tang, Kevin; Haustein, Karsten; Allen, Myles R.

2018-05-01

Empirical evidence suggests that variations in climate affect economic growth across countries over time. However, little is known about the relative impacts of climate change on economic outcomes when global mean surface temperature (GMST) is stabilized at 1.5°C or 2°C warming relative to pre-industrial levels. Here we use a new set of climate simulations under 1.5°C and 2°C warming from the `Half a degree Additional warming, Prognosis and Projected Impacts' (HAPPI) project to assess changes in economic growth using empirical estimates of climate impacts in a global panel dataset. Panel estimation results that are robust to outliers and breaks suggest that within-year variability of monthly temperatures and precipitation has little effect on economic growth beyond global nonlinear temperature effects. While expected temperature changes under a GMST increase of 1.5°C lead to proportionally higher warming in the Northern Hemisphere, the projected impact on economic growth is larger in the Tropics and Southern Hemisphere. Accounting for econometric estimation and climate uncertainty, the projected impacts on economic growth of 1.5°C warming are close to indistinguishable from current climate conditions, while 2°C warming suggests statistically lower economic growth for a large set of countries (median projected annual growth up to 2% lower). Level projections of gross domestic product (GDP) per capita exhibit high uncertainties, with median projected global average GDP per capita approximately 5% lower at the end of the century under 2°C warming relative to 1.5°C. The correlation between climate-induced reductions in per capita GDP growth and national income levels is significant at the p < 0.001 level, with lower-income countries experiencing greater losses, which may increase economic inequality between countries and is relevant to discussions of loss and damage under the United Nations Framework Convention on Climate Change. This article is part of the

Preparation of 13C/15N-labeled oligomers using the polymerase chain reaction

DOEpatents

Chen, Xian; Gupta, Goutam; Bradbury, E. Morton

2001-01-01

Preparation of .sup.13 C/.sup.15 N-labeled DNA oligomers using the polymerase chain reaction (PCR). A PCR based method for uniform (.sup.13 C/.sup.15 N)-labeling of DNA duplexes is described. Multiple copies of a blunt-ended duplex are cloned into a plasmid, each copy containing the sequence of interest and restriction Hinc II sequences at both the 5' and 3' ends. PCR using bi-directional primers and uniformly .sup.13 C/.sup.15 N-labeled dNTP precursors generates labeled DNA duplexes containing multiple copies of the sequence of interest. Twenty-four cycles of PCR, followed by restriction and purification, gave the uniformly .sup.13 C/.sup.15 N-labeled duplex sequence with a 30% yield. Such labeled duplexes find significant applications in multinuclear magnetic resonance spectroscopy.

Solvothermal synthesis of Fe{sub 7}C{sub 3} and Fe{sub 3}C nanostructures with phase and morphology control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Brent; Clifford, Dustin; Carpenter, Everett E., E-mail: aelgendy@vcu.edu, E-mail: ecarpenter2@vcu.edu

A phase transition, from orthorhombic Fe{sub 3}C to hexagonal Fe{sub 7}C{sub 3}, was observed using a wet synthesis mediated by hexadecyltrimethylammonium chloride (CTAC). In this study, CTAC has been shown to control carbide phase, morphology, and size of the iron carbide nanostructures. Fe{sub 7}C{sub 3} hexagonal prisms were formed with an average diameter of 960 nm, the thickness of 150 nm, and Fe{sub 3}C nanostructures with an approximate size of 50 nm. Magnetic studies show ferromagnetic behavior with M{sub s} of 126 emu/g, and H{sub c} of 170 Oe with respect to Fe{sub 7}C{sub 3} and 95 emu/g and 590 Oe with respect to Fe{sub 3}C. Themore » thermal studies using high temperature x-ray diffraction show stability of Fe{sub 7}C{sub 3} up to 500 °C. Upon slow cooling, the Fe{sub 7}C{sub 3} phase is recovered with an intermediate oxide phase occurring around 300 °C. This study has demonstrated a simple route in synthesizing iron carbides for an in depth magnetic study and crystal phase transition study of Fe{sub 7}C{sub 3} at elevated temperatures.« less

Structure of C 14 and B 14 from the C 14 , 15 ( d , He 3 ) B 13 , 14 reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bedoor, S.; Wuosmaa, A. H.; Albers, M.

We have studied the C-14,C-15(d,He-3)B-13,B-14 proton-removing reactions in inverse kinematics. The (d,He-3) reaction probes the proton occupation of the target ground state, and also provides spectroscopic information about the final states in B-13,B-14. The experiments were performed using C-14,C-15 beams from the ATLAS accelerator at Argonne National Laboratory. The reaction products were analyzed with the HELIOS device. Angular distributions were obtained for transitions from both reactions. The C-14-beam data reveal transitions to excited states in B-13 that suggest configurations with protons outside the pi(0p(3/2)) orbital, and some possibility of proton cross-shell 0p-1s0d excitations, in the C-14 ground state. The C-15-beammore » data confirm the existence of a broad 2(-) excited state in B-14. The experimental data are compared to the results of shell-model calculations.« less

CARBON-RICH PRESOLAR GRAINS FROM MASSIVE STARS: SUBSOLAR {sup 12}C/{sup 13}C AND {sup 14}N/{sup 15}N RATIOS AND THE MYSTERY OF {sup 15}N

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pignatari, M.; Zinner, E.; Hoppe, P.

2015-08-01

Carbon-rich grains with isotopic anomalies compared to the Sun are found in primitive meteorites. They were made by stars, and carry the original stellar nucleosynthesis signature. Silicon carbide grains of Type X and C and low-density (LD) graphites condensed in the ejecta of core-collapse supernovae. We present a new set of models for the explosive He shell and compare them with the grains showing {sup 12}C/{sup 13}C and {sup 14}N/{sup 15}N ratios lower than solar. In the stellar progenitor H was ingested into the He shell and not fully destroyed before the explosion. Different explosion energies and H concentrations aremore » considered. If the supernova shock hits the He-shell region with some H still present, the models can reproduce the C and N isotopic signatures in C-rich grains. Hot-CNO cycle isotopic signatures are obtained, including a large production of {sup 13}C and {sup 15}N. The short-lived radionuclides {sup 22}Na and {sup 26}Al are increased by orders of magnitude. The production of radiogenic {sup 22}Ne from the decay of {sup 22}Na in the He shell might solve the puzzle of the Ne-E(L) component in LD graphite grains. This scenario is attractive for the SiC grains of type AB with {sup 14}N/{sup 15}N ratios lower than solar, and provides an alternative solution for SiC grains originally classified as nova grains. Finally, this process may contribute to the production of {sup 14}N and {sup 15}N in the Galaxy, helping to produce the {sup 14}N/{sup 15}N ratio in the solar system.« less

Antihalo effects on reaction cross sections for C14,15,16 isotopes

NASA Astrophysics Data System (ADS)

Matsumoto, Takuma; Yahiro, Masanobu

2014-10-01

We study antihalo effects on reaction cross sections σR for C14,15,16 scattering from a C12 target at 83 MeV/nucleon, using the g-matrix double-folding model. C15 is described by the 14C+n two-body model that reproduces the measured large s-wave spectroscopic factor, i.e., the shell inversion that the 1s1/2 orbital is lower than the 0d5/2 orbital in energy. C16 is described by the 14C+n+n three-body model with the phenomenological three-body force (3BF) that explains the measured small s-wave spectroscopic factor. The 3BF allows the single-particle energies of the 14C+n subsystem to depend on the position r of the second neutron from the center of mass of the subsystem. The 1s1/2 orbital is lower than the 0d5/2 orbital for large r, but the shell inversion is restored for small r. Antihalo effects due to the "partial shell inversion" make σR for C16 smaller than that for C15. We also investigate projectile breakup effects on the mass-number dependence of σR with the continuum-discretized coupled-channel method.

Isothermal fatigue behavior of a (90)(sub 8) SiC/Ti-15-3 composite at 426 C

NASA Technical Reports Server (NTRS)

Gayda, John; Gabb, Timothy P.

1991-01-01

The transverse fatigue behavior of a unidirectional, SiC/Ti-15-3 composite (35 v/o SiC, (90)(sub 8)) was evaluated at 426 C. The fatigue behavior of the composite along the fiber direction (0)(sub 8) and of unreinforced Ti-15-3 alloy were also studied for comparison purposes. The (90)(sub 8) composite fatigue life was much shorter then (0)(sub 8) life. Further, (90)(sub 8) fatigue life was also found to be far lower than that of the unreinforced Ti-15-3 alloys. A simple one-dimensional model for (90)(sub 8) fatigue behavior indicated that the short life of the composite in this orientation resulted, in large part, from weak fiber-matrix bond strength. This conclusion was supported by fractographic evidence showing numerous initiation sites along the fiber-matrix interfaces.

7Li(15N, 14C)8Be reaction at 81 MeV and 14C + 8Be interaction versus that of 13C + 8Be

NASA Astrophysics Data System (ADS)

Rudchik, A. T.; Rudchik, A. A.; Muravynets, L. M.; Kemper, K. W.; Rusek, K.; Koshchy, E. I.; Piasecki, E.; Trzcinska, A.; Pirnak, Val. M.; Ponkratenko, O. A.; Strojek, I.; Stolarz, A.; Plujko, V. A.; Sakuta, S. B.; Siudak, R.; Ilyin, A. P.; Stepanenko, Yu. M.; Shyrma, Yu. O.; Uleshchenko, V. V.

2018-03-01

Angular distributions of the 7Li(15N, 14C)8Be reaction were measured at the energy Elab(15N) = 81 MeV. Data for transfer to the ground and first two excited states in 8Be were acquired as well as to the 14C ground and excited states. The reaction data were analyzed within the coupled-reaction-channels (CRC) method. The required 15N + 7Li entrance channel potential was taken from the 15N + 7Li elastic scattering. The 14C + 8Be potential was found by fitting Woods-Saxon form potentials to those generated by double folded real and imaginary potentials in the region of interaction. These generated potentials were then used in the CRC calculations. Proton transfer dominants this reaction, including to the excited states of 8Be. The reaction dependence on the exit channel potential was examined by using the 13C + 8Be potential previously deduced from the 9Be(12C, 13C)8Be reaction and 14C + 8Be from the 13C(9Be, 8Be)14C reaction.

Impact delivery of organic matter on the acapulcoite-lodranite parent-body deduced from C, N isotopes and nanostructures of carbon phases in Acapulco and Lodran

NASA Astrophysics Data System (ADS)

Charon, E.; Aléon, J.; Rouzaud, J.-N.

2014-10-01

The structure and nanostructures of carbon phases from the Acapulco and Lodran meteorites and their carbon and nitrogen isotopic composition were investigated at the nanometer and micrometer scale using a systematic combination of Raman microspectrometry, high-resolution transmission electron microscopy and secondary ion mass spectrometry to determine their origin and thermal evolution. Several morphological types were recognized belonging to roughly two isotopic and structural families: coarse carbon grains and rosettes, only found in Acapulco, and vein-like carbon occurrences present in both Acapulco and Lodran. Carbon phases in Acapulco are highly graphitized, and show a genetic relationship with metal indicative of metal-assisted graphitization. By contrast, carbon phases in Lodran are exclusively disordered mesoporous turbostratic carbons, in spite of their inclusion in metal and the higher peak temperature experienced by the Lodran parent body. δ13C values range between -59‰ and +37‰ in Acapulco and between -38‰ and -1‰ in Lodran and show in both cases a peak in their distribution at the value of chondritic insoluble organic matter (IOM, -10‰ to -15‰). N concentrations together with δ15N values indicate a mixing between a component akin to chondritic IOM in Lodran with a δ15N value around +10‰ to +20‰ and a component akin to that in the most N-poor Acapulco graphites. The latter are systematically depleted in 15N with a δ15N value constant at ∼-140‰ for N concentrations below ∼1.4 wt%. These observations can be explained if carbon phases in Acapulco and Lodran result from the late impact introduction of CI-CM like IOM, after significant cooling of the parent-body, and subsequent carbonization and graphitization of IOM by interaction with FeNi metal by the heat wave induced by the impact. Temperatures probably reached 900 °C in Acapulco, enough to achieve metal-assisted graphitization but were not significantly higher than 650 °C in

Mapping the Superconducting Anti-ferromagnetic C4 Phase in Iron-Pnictides

NASA Astrophysics Data System (ADS)

Stadel, Ryan; Taddei, Keith; Bugaris, Dan; Lapidus, Saul; Claus, Helmut; Phelan, Daniel; Chung, Duck Young; Kanatzidis, Mercouri; Osborn, Raymond; Rosenkranz, Stephan; Chmaissem, Omar

Following the discovery of the microscopic coexistence of antifermagnetic spin density waves and superconductivity in Ba1-xKxFe2As2 and the low temperature re-entrance to the novel magnetic C4 tetragonal phase in Ba1-xNaxFe2As2, there has been significant interest in developing an understanding of the properties and formation of these phases and analyzing their dependence on temperature and composition in hole-doped 122 alkaline earth metal/iron-pnictides. We describe the mapping of various Ba, Sr, and Ca 122 phase diagrams with systematically controlled levels of hole-doping of alkaline metal onto the alkaline earth metal site, which was investigated via x-ray and neutron diffraction. Our elaborate synthesis, diffraction work, and analysis maps and firmly establishes the C4 phase space in these ternary diagrams as well as the boundary lines that separate the individual phases, and provides natural clues as well as a framework to investigate the stability and formation of the C4 domes that shift location with doping contents in the phase diagrams. Work at Argonne was supported by US DOE, Office of Science, Materials Sciences and Engineering Division.

Novel benzo-15-crown-5 sol-gel coating for solid-phase microextraction.

PubMed

Wang, Danhua; Xing, Jun; Peng, Jiagang; Wu, Caiying

2003-07-11

A novel dihydroxy-terminated benzo-15-crown-5 was synthesized and applied to prepare a solid-phase microextraction (SPME) fiber coating with sol-gel technology. The optimization of the sol-gel process was studied. The coating method with sol-gel was improved and completed in one run, which economized materials and allowed easier control of the fiber thickness. The repeatability of coating fiber to fiber was better than 4.94% (RSD). The surface of the fiber coating was well-distributed and an electron microscopy experiment suggested a porous structure for crown ether coating, providing high surface areas and allowing for high extraction efficiency. The coating has a high thermal stability (350 degrees C), long lifetime and can stand solvent (organic and inorganic) rinsing due to the chemical binding between the coating and the fiber surface. Non-polar benzene, toluene, ethylbenzene, xylenes, chlorobenzenes, polar phenolic compounds and arylamines were used to evaluate the character of the fiber coating by headspace SPME-gas chromatography technology. For phenols, the linear concentrations ranged from 5 to 1000 microg/l, the detection limits were between 0.05 and 1 microg/l, and the RSD was less than 5%. The addition of benzo-crown ether not only increases the thermal stability of the fiber coating, but also enhances the selectivity of the fiber coating. Compared with commercially available SPME fibers poly(dimethylsiloxane) and polyacrylate, the few phases showed better selectivity and sensitivity towards non-polar and polar aromatic compounds.

Effect of V2O5 Addition on the Phase Composition of Bi5FeTi3O15 Ceramic and RF/Microwave Dielectric Properties

NASA Astrophysics Data System (ADS)

Aguiar, F. A. A.; Sales, A. J. M.; Araújo, B. S.; Sabóia, K. D. A.; Filho, M. C. Campos; Sombra, A. S. B.; Ayala, A. P.; Fechine, P. B. A.

2017-04-01

Bi5FeTi3O15 (BFT) polycrystalline ceramic with the addition of different concentrations of V2O5 was obtained by a solid-state method. X-ray powder diffraction, Raman spectroscopy and scanning electron microscopy (SEM) were used to study the microstructure and crystalline phases of the ceramics. SEM images showed plate-like morphology with dimensions between 0.32 μm and 3.07 μm (grain size, average around 1.3 μm). For samples with V2O5 concentration below 5%, Raman spectra were mainly determined by the vibrational modes from BFT. Impedance spectroscopy was also performed to evaluate the dielectric properties at microwave and radio frequencies (RF). Two extra phases (Bi4V1.5Fe0.5O10.5 and Bi2Ti2O7) were found due to the chemical reaction between BFT and V2O5. These phases were responsible for the changes in the grain morphology and dielectric response. V2O5 addition increased the real part of the dielectric permittivity ( ɛ') and reduced the dielectric loss tangent (tan δ) values at the RF range of 10 Hz to 1 MHz. For microwave frequencies of 3-3.5 GHz, ɛ' and temperature coefficient of resonant frequency ( τ f) values ranged from 66.52 ppm/°C to 88.60 ppm/°C and -304.3 ppm/°C to -192.6 ppm/°C, respectively. Thereby, BFT ceramics with added V2O5 are good candidates to be used for microwave devices (e.g., cell phones).

Tensile strength and creep behaviour of austenitic stainless steel type 18Cr - 12Ni with niobium additions at 700°C

NASA Astrophysics Data System (ADS)

Sordi, V. L.; Bueno, L. O.

2010-07-01

The effect of niobium additions up to 2.36 wt% on the creep behavior of a series of seven extra low carbon 18Cr-12Ni austenitic stainless steels at 700°C has been investigated. Grain size and hardness measurements, hot tensile tests and constant stress creep tests from 90 to 180 MPa were carried out for each alloy, in the solution treated condition at 1050, 1200 and 1300°C followed by quench in water. The mechanical behavior at high temperature was related to the amount of NbC precipitation occurring during the tests. Solid solution and intermetallic compound effects were also considered. Creep data analysis was done to determine the parameters of the creep power-law equation dot epsilon = A.σn and the Monkman-Grant relation dot epsilon.tmR = K. Niobium-carbide precipitation in these steels reduces the secondary stage dependence of strain rate with applied stress, resulting in n-values which indicate the possibility of operation of various creep mechanisms. The creep strength during the secondary stage is primarily controlled by the amount of NbC available for precipitation. However, the rupture times increase progressively with niobium content, as the amount of undissolved carbide particles in grain boundaries and the Laves phase precipitation increase.

UAS C2 Radio System - Final Phase 1 Development and Testing

NASA Technical Reports Server (NTRS)

Kerczewski, Robert; Shalkhauser, Kurt

2017-01-01

Phase 1 of the Command and Control Communications (C2) Subproject of NASA's UAS Integration in the National Airspace System Project included the development and testing of prototype C2 radio systems. This information paper provides an overview of the functionality and testing of the fifth and final Phase 1 generation of the prototype radio system.

Parallel Allostery by cAMP and PDE Coordinates Activation and Termination Phases in cAMP Signaling.

PubMed

Krishnamurthy, Srinath; Tulsian, Nikhil Kumar; Chandramohan, Arun; Anand, Ganesh S

2015-09-15

The second messenger molecule cAMP regulates the activation phase of the cAMP signaling pathway through high-affinity interactions with the cytosolic cAMP receptor, the protein kinase A regulatory subunit (PKAR). Phosphodiesterases (PDEs) are enzymes responsible for catalyzing hydrolysis of cAMP to 5' AMP. It was recently shown that PDEs interact with PKAR to initiate the termination phase of the cAMP signaling pathway. While the steps in the activation phase are well understood, steps in the termination pathway are unknown. Specifically, the binding and allosteric networks that regulate the dynamic interplay between PKAR, PDE, and cAMP are unclear. In this study, PKAR and PDE from Dictyostelium discoideum (RD and RegA, respectively) were used as a model system to monitor complex formation in the presence and absence of cAMP. Amide hydrogen/deuterium exchange mass spectrometry was used to monitor slow conformational transitions in RD, using disordered regions as conformational probes. Our results reveal that RD regulates its interactions with cAMP and RegA at distinct loci by undergoing slow conformational transitions between two metastable states. In the presence of cAMP, RD and RegA form a stable ternary complex, while in the absence of cAMP they maintain transient interactions. RegA and cAMP each bind at orthogonal sites on RD with resultant contrasting effects on its dynamics through parallel allosteric relays at multiple important loci. RD thus serves as an integrative node in cAMP termination by coordinating multiple allosteric relays and governing the output signal response. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

17 CFR 240.15c1-7 - Discretionary accounts.

Code of Federal Regulations, 2010 CFR

2010-04-01

... Securities Exchange Act of 1934 Rules Relating to Over-The-Counter Markets § 240.15c1-7 Discretionary... transactions or purchase or sale which are excessive in size or frequency in view of the financial resources...

17 CFR 240.15c1-7 - Discretionary accounts.

Code of Federal Regulations, 2011 CFR

2011-04-01

... Securities Exchange Act of 1934 Rules Relating to Over-The-Counter Markets § 240.15c1-7 Discretionary... transactions or purchase or sale which are excessive in size or frequency in view of the financial resources...

Uncertain impacts on economic growth when stabilizing global temperatures at 1.5°C or 2°C warming

PubMed Central

Schwarz, Moritz; Tang, Kevin; Haustein, Karsten; Allen, Myles R.

2018-01-01

Empirical evidence suggests that variations in climate affect economic growth across countries over time. However, little is known about the relative impacts of climate change on economic outcomes when global mean surface temperature (GMST) is stabilized at 1.5°C or 2°C warming relative to pre-industrial levels. Here we use a new set of climate simulations under 1.5°C and 2°C warming from the ‘Half a degree Additional warming, Prognosis and Projected Impacts' (HAPPI) project to assess changes in economic growth using empirical estimates of climate impacts in a global panel dataset. Panel estimation results that are robust to outliers and breaks suggest that within-year variability of monthly temperatures and precipitation has little effect on economic growth beyond global nonlinear temperature effects. While expected temperature changes under a GMST increase of 1.5°C lead to proportionally higher warming in the Northern Hemisphere, the projected impact on economic growth is larger in the Tropics and Southern Hemisphere. Accounting for econometric estimation and climate uncertainty, the projected impacts on economic growth of 1.5°C warming are close to indistinguishable from current climate conditions, while 2°C warming suggests statistically lower economic growth for a large set of countries (median projected annual growth up to 2% lower). Level projections of gross domestic product (GDP) per capita exhibit high uncertainties, with median projected global average GDP per capita approximately 5% lower at the end of the century under 2°C warming relative to 1.5°C. The correlation between climate-induced reductions in per capita GDP growth and national income levels is significant at the p < 0.001 level, with lower-income countries experiencing greater losses, which may increase economic inequality between countries and is relevant to discussions of loss and damage under the United Nations Framework Convention on Climate Change. This article is part of

Uncertain impacts on economic growth when stabilizing global temperatures at 1.5°C or 2°C warming.

PubMed

Pretis, Felix; Schwarz, Moritz; Tang, Kevin; Haustein, Karsten; Allen, Myles R

2018-05-13

Empirical evidence suggests that variations in climate affect economic growth across countries over time. However, little is known about the relative impacts of climate change on economic outcomes when global mean surface temperature (GMST) is stabilized at 1.5°C or 2°C warming relative to pre-industrial levels. Here we use a new set of climate simulations under 1.5°C and 2°C warming from the 'Half a degree Additional warming, Prognosis and Projected Impacts' (HAPPI) project to assess changes in economic growth using empirical estimates of climate impacts in a global panel dataset. Panel estimation results that are robust to outliers and breaks suggest that within-year variability of monthly temperatures and precipitation has little effect on economic growth beyond global nonlinear temperature effects. While expected temperature changes under a GMST increase of 1.5°C lead to proportionally higher warming in the Northern Hemisphere, the projected impact on economic growth is larger in the Tropics and Southern Hemisphere. Accounting for econometric estimation and climate uncertainty, the projected impacts on economic growth of 1.5°C warming are close to indistinguishable from current climate conditions, while 2°C warming suggests statistically lower economic growth for a large set of countries (median projected annual growth up to 2% lower). Level projections of gross domestic product (GDP) per capita exhibit high uncertainties, with median projected global average GDP per capita approximately 5% lower at the end of the century under 2°C warming relative to 1.5°C. The correlation between climate-induced reductions in per capita GDP growth and national income levels is significant at the p  < 0.001 level, with lower-income countries experiencing greater losses, which may increase economic inequality between countries and is relevant to discussions of loss and damage under the United Nations Framework Convention on Climate Change.This article is part of

Exploration of phase transition in Th2C under pressure: An Ab-initio investigation

NASA Astrophysics Data System (ADS)

Sahoo, B. D.; Joshi, K. D.; Kaushik, T. C.

2018-05-01

With the motivation of searching for new compounds in the Th-C system, we have performed ab initio evolutionary searches for all the stable compounds in this binary system in the pressure range of 0-100 GPa. We have found previously unknown, thermodynamically stable, composition Th2C along with experimentally known ThC, ThC2 and Th2C3 phases at 0 GPa. Interestingly at pressure of 13 GPa the predicted ground state orthorhombic (SG no. 59, Pmmn) phase of Th2C transforms to trigonal (SG no. 164, P-3m1) phase. We also find the mechanical and dynamical stability of both the phases. Further, the theoretically determined equation of state has been utilized to derive various physical quantities such as zero pressure equilibrium volume, bulk modulus, and pressure derivative of bulk modulus of Pmmn phase at ambient conditions.

High-performance for hydrogen evolution and pollutant degradation of reduced graphene oxide/two-phase g-C3N4 heterojunction photocatalysts.

PubMed

Song, Chengjie; Fan, Mingshan; Shi, Weidong; Wang, Wei

2018-05-01

We have successfully synthesized the composites of two-phase g-C 3 N 4 heterojunction photocatalysts by one-step method. And the reduced graphene oxide/two-phase g-C 3 N 4 heterojunction photocatalyst was fabricated via a facile hydrothermal reduction method. The characterization results indicated that the two-phase g-C 3 N 4 was integrated closely, and the common phenomenon of agglomeration for g-C 3 N 4 was significantly reduced. Moreover, the oxidized graphene was reduced successfully in the composites and the graphene was overlaid on the surface or the interlayers of g-C 3 N 4 heterojunction composite uniformly. In addition, we have carried out the photocatalytic activity experiments by H 2 evolution and rhodamine B removal, tetracycline removal under the visible light irradiation. The results revealed that the composite has improved the separation efficiency a lot than the pure photocatalyst. The photocurrent test demonstrated that the recombination of electrons and holes were efficiently inhibited as well as enhanced the photocatalytic activity. The 0.4% rGO loaded samples, 0.4% rGOCN2, own the best performance. Its rate of H 2 evolution was 15 times as high as that of the pure g-C 3 N 4 .

Record-breaking climate extremes in Africa under stabilized 1.5 °C and 2 °C global warming scenarios

NASA Astrophysics Data System (ADS)

Nangombe, Shingirai; Zhou, Tianjun; Zhang, Wenxia; Wu, Bo; Hu, Shuai; Zou, Liwei; Li, Donghuan

2018-05-01

Anthropogenic forcing is anticipated to increase the magnitude and frequency of extreme events1, the impacts of which will be particularly hard-felt in already vulnerable locations such as Africa2. However, projected changes in African climate extremes remain little explored, particularly in the context of the Paris Agreement targets3,4. Here, using Community Earth System Model low warming simulations5, we examine how heat and hydrological extremes may change in Africa under stabilized 1.5 °C and 2 °C scenarios, focusing on the projected changing likelihood of events that have comparable magnitudes to observed record-breaking seasons. In the Community Earth System Model, limiting end-of-century warming to 1.5 °C is suggested to robustly reduce the frequency of heat extremes compared to 2 °C. In particular, the probability of events similar to the December-February 1991/1992 southern African and 2009/2010 North African heat waves is estimated to be reduced by 25 ± 5% and 20 ± 4%, respectively, if warming is limited to 1.5 °C instead of 2 °C. For hydrometeorological extremes (that is, drought and heavy precipitation), by contrast, signal differences are indistinguishable from the variation between ensemble members. Thus, according to this model, continued efforts to limit warming to 1.5 °C offer considerable benefits in terms of minimizing heat extremes and their associated socio-economic impacts across Africa.

Is the zero emission requirement aligned with 2.0°C and 1.5°C stabilization targets?

NASA Astrophysics Data System (ADS)

Tanaka, K.; O'Neill, B. C.

2016-12-01

The Paris Agreement stipulates that the global warming be stabilized at well below 2°C and eventually 1.5°C above pre-industrial levels. While the landmark agreement has led to a wide range of associated analyses, less attention has been paid to another mitigation target in Paris: cut the net greenhouse gas emissions to zero during the second half of this century. This study explores how such an emission target may guide us to achieve the temperature target. We found that, if the emission target is met by 2060, the most likely outcome is that the warming will peak at slightly above 2°C and decline below 1.5°C by the early 22nd century. This corresponds roughly to the temperature target; however, it is important to realize that the warming inevitably exceeds 1.5°C temporarily. On the contrary, if delayed by 2100, the warming reaches as high as 4°C until it starts to fall. Furthermore, net negative CO2 emissions are implicitly required for the emission target, the intensity of which depends on unabatable anthropogenic non-CO2 greenhouse gas emissions as well as the emission metric used to equate greenhouse gas emissions on the basis of CO2.

17 CFR 240.15c1-9 - Use of pro forma balance sheets.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 17 Commodity and Securities Exchanges 3 2011-04-01 2011-04-01 false Use of pro forma balance sheets. 240.15c1-9 Section 240.15c1-9 Commodity and Securities Exchanges SECURITIES AND EXCHANGE... pro forma balance sheets. The term manipulative, deceptive, or other fraudulent device or contrivance...

17 CFR 240.15c1-9 - Use of pro forma balance sheets.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Use of pro forma balance sheets. 240.15c1-9 Section 240.15c1-9 Commodity and Securities Exchanges SECURITIES AND EXCHANGE... pro forma balance sheets. The term manipulative, deceptive, or other fraudulent device or contrivance...

Effect of pressure on the selectivity of polymeric C18 and C30 stationary phases in reversed-phase liquid chromatography. Increased separation of isomeric fatty acid methyl esters, triacylglycerols, and tocopherols at high pressure.

PubMed

Okusa, Kensuke; Iwasaki, Yuki; Kuroda, Ikuma; Miwa, Shohei; Ohira, Masayoshi; Nagai, Toshiharu; Mizobe, Hoyo; Gotoh, Naohiro; Ikegami, Tohru; McCalley, David V; Tanaka, Nobuo

2014-04-25

A high-density, polymeric C18 stationary phase (Inertsil ODS-P) or a polymeric C30 phase (Inertsil C30) provided improved resolution of the isomeric fatty acids (FAs), FA methyl esters (FAMEs), triacylglycerols (TAGs), and tocopherols with an increase in pressure of 20-70MPa in reversed-phase HPLC. With respect to isomeric C18 FAMEs with one cis-double bond, ODS-P phase was effective for recognizing the position of a double bond among petroselinic (methyl 6Z-octadecenoate), oleic (methyl 9Z-octadecenoate), and cis-vaccenic (methyl 11Z-octadecenoate), especially at high pressure, but the differentiation between oleic and cis-vaccenic was not achieved by C30 phase regardless of the pressure. A monomeric C18 phase (InertSustain C18) was not effective for recognizing the position of the double bond in monounsaturated FAME, while the separation of cis- and trans-isomers was achieved by any of the stationary phases. The ODS-P and C30 phases provided increased separation for TAGs and β- and γ-tocopherols at high pressure. The transfer of FA, FAME, or TAG molecules from the mobile phase to the ODS-P stationary phase was accompanied by large volume reduction (-30∼-90mL/mol) resulting in a large increase in retention (up to 100% for an increase of 50MPa) and improved isomer separation at high pressure. For some isomer pairs, the ODS-P and C30 provided the opposite elution order, and in each case higher pressure improved the separation. The two stationary phases showed selectivity for the isomers having rigid structures, but only the ODS-P was effective for differentiating the position of a double bond in monounsaturated FAMEs. The results indicate that the improved isomer separation was provided by the increased dispersion interactions between the solute and the binding site of the stationary phase at high pressure. Copyright © 2014 Elsevier B.V. All rights reserved.

Preparation, characterization and application of a reversed phase liquid chromatography/hydrophilic interaction chromatography mixed-mode C18-DTT stationary phase.

PubMed

Wang, Qing; Long, Yao; Yao, Lin; Xu, Li; Shi, Zhi-Guo; Xu, Lanying

2016-01-01

A mixed-mode chromatographic stationary phase, C18-DTT (dithiothreitol) silica (SiO2) was prepared through "thiol-ene" click chemistry. The obtained material was characterized by fourier transform infrared spectroscope, nitrogen adsorption analysis and contact angle analysis. Chromatographic performance of the C18-DTT was systemically evaluated by studying the effect of acetonitrile content, pH, buffer concentration of the mobile phase and column temperature. It was demonstrated that the novel stationary phase possessed reversed phase liquid chromatography (RPLC)/hydrophilic interaction liquid chromatography (HILIC) mixed-mode property. The stop-flow test revealed that C18-DTT exhibited excellent compatibility with 100% aqueous mobile phase. Additionally, the stability and column-to-column reproducibility of the C18-DTT material were satisfactory, with relative standard deviations of retention factor of the tested analytes (verapamil, fenbufen, guanine, tetrandrine and nicotinic acid) in the range of 1.82-3.72% and 0.85-1.93%, respectively. Finally, the application of C18-DTT column was demonstrated in the separation of non-steroidal anti-inflammatory drugs, aromatic carboxylic acids, alkaloids, nucleo-analytes and polycyclic aromatic hydrocarbons. It had great resolving power in the analysis of various compounds in HILIC and RPLC chromatographic conditions and was a promising RPLC/HILIC mixed-mode stationary phase. Copyright © 2015 Elsevier B.V. All rights reserved.

Future emissions pathways consistent with limiting warming to 1.5°C

NASA Astrophysics Data System (ADS)

Millar, R.; Fuglestvedt, J. S.; Grubb, M.; Rogelj, J.; Skeie, R. B.; Friedlingstein, P.; Forster, P.; Frame, D. J.; Pierrehumbert, R.; Allen, M. R.

2016-12-01

The stated aim of the 2015 UNFCCC Paris Agreement is `holding the increase in global average temperature to well below 2°C above pre-industrial levels and to pursue efforts to limit temperature increases to 1.5°C'. We show that emissions reductions proportional to those achieved in an ambitious mitigation scenario, RCP2.6, but beginning in 2017, give a median estimated peak warming of 1.5°C, with a likely (66% probability) range of uncertainty of 1.2-2.0°C. Such a scenario would be approximately consistent with the most ambitious interpretation of the 2030 emissions pledges, but requires reduction rates exceeding 0.3GtC/yr/yr after 2030. A steady reduction at less than half this rate would achieve the same temperature outcome if initiated in 2020. Limiting total CO2 emissions after 2015 to 200GtC would limit future warming to likely less than 0.6°C above present, consistent with 1.5°C above pre-industrial, based on the distribution of responses of the CMIP5 Earth System, but the CMIP5 simulations do not correspond to scenarios that aim to limit warming to such low levels. If future CO2 emissions are successfully adapted to the emerging climate response so as to limit warming in 2100 to 0.6°C above present, and non-CO2 emissions follow the ambitious RCP2.6 scenario, then we estimate that resulting CO2 emissions will unlikely be restricted to less than 250GtC given current uncertainties in climate system response, although still-poorly-modelled carbon cycle feedbacks, such as release from permafrost, may encroach on this budget. Even under a perfectly successful adaptive mitigation regime, emissions consistent with limiting warming to 0.6°C above present are unlikely to be greater than 500GtC.These estimates suggest the 1.5°C goal may not yet be geophysically insurmountable but will nevertheless require, at minimum, the full implementation of the most ambitious interpretation of the Paris pledges followed by accelerated and more fundamental changes in our

NMR of enzymatically synthesized uniformly 13C15N-labeled DNA oligonucleotides.

PubMed Central

Zimmer, D P; Crothers, D M

1995-01-01

A procedure for the enzymatic synthesis of uniformly 13C15N-labeled DNA oligonucleotides in milligram quantities for NMR studies is described. Deoxynucleotides obtained from microorganisms grown on 13C and 15N nutrient sources are enzymatically phosphorylated to dNTPs, and the dNTPs are incorporated into oligonucleotides using a 3'-5' exonuclease-deficient mutant of Klenow fragment of DNA polymerase I and an oligonucleotide template primer designed for efficient separation of labeled product DNA from unlabeled template. The labeling strategy has been used to uniformly label one or the other oligonucleotide strand in the DNA duplex dGGCAAAACGG.dCCGTTTTGCC in order to facilitate assignment and structure determination by NMR. Application of 15N and 13C heteronuclear NMR experiments to isotopically labeled DNA is presented. Images Fig. 2 Fig. 3 Fig. 4 PMID:7724521

Scenario dependence of future changes in climate extremes under 1.5 °C and 2 °C global warming

NASA Astrophysics Data System (ADS)

Wang, Zhili; Lin, Lei; Zhang, Xiaoye; Zhang, Hua; Liu, Liangke; Xu, Yangyang

2017-04-01

The 2015 Paris Agreement aims to limit global warming below 2 °C and pursue efforts to even limit it to 1.5 °C relative to pre-industrial levels. Decision makers need reliable information on the impacts caused by these warming levels for climate mitigation and adaptation measures. We explore the changes in climate extremes, which are closely tied to economic losses and casualties, under 1.5 °C and 2 °C global warming and their scenario dependence using three sets of ensemble global climate model simulations. A warming of 0.5 °C (from 1.5 °C to 2 °C) leads to significant increases in temperature and precipitation extremes in most regions. However, the projected changes in climate extremes under both warming levels highly depend on the pathways of emissions scenarios, with different greenhouse gas (GHG)/aerosol forcing ratio and GHG levels. Moreover, there are multifold differences in several heavily polluted regions, among the scenarios, in the changes in precipitation extremes due to an additional 0.5 °C warming from 1.5 °C to 2 °C. Our results demonstrate that the chemical compositions of emissions scenarios, not just the total radiative forcing and resultant warming level, must be considered when assessing the impacts of global 1.5/2 °C warming.

Scenario dependence of future changes in climate extremes under 1.5 °C and 2 °C global warming.

PubMed

Wang, Zhili; Lin, Lei; Zhang, Xiaoye; Zhang, Hua; Liu, Liangke; Xu, Yangyang

2017-04-20

The 2015 Paris Agreement aims to limit global warming below 2 °C and pursue efforts to even limit it to 1.5 °C relative to pre-industrial levels. Decision makers need reliable information on the impacts caused by these warming levels for climate mitigation and adaptation measures. We explore the changes in climate extremes, which are closely tied to economic losses and casualties, under 1.5 °C and 2 °C global warming and their scenario dependence using three sets of ensemble global climate model simulations. A warming of 0.5 °C (from 1.5 °C to 2 °C) leads to significant increases in temperature and precipitation extremes in most regions. However, the projected changes in climate extremes under both warming levels highly depend on the pathways of emissions scenarios, with different greenhouse gas (GHG)/aerosol forcing ratio and GHG levels. Moreover, there are multifold differences in several heavily polluted regions, among the scenarios, in the changes in precipitation extremes due to an additional 0.5 °C warming from 1.5 °C to 2 °C. Our results demonstrate that the chemical compositions of emissions scenarios, not just the total radiative forcing and resultant warming level, must be considered when assessing the impacts of global 1.5/2 °C warming.

Microstructural Evolution and Phase Formation in 2nd-Generation Refractory-Based High Entropy Alloys

PubMed Central

Eshed, Eyal; Larianovsky, Natalya; Kovalevsky, Alexey; Popov, Vladimir; Gorbachev, Igor; Popov, Vladimir; Katz-Demyanetz, Alexander

2018-01-01

Refractory-based high entropy alloys (HEAs) of the 2nd-generation type are new intensively-studied materials with a high potential for structural high-temperature applications. This paper presents investigation results on microstructural evolution and phase formation in as-cast and subsequently heat-treated HEAs at various temperature-time regimes. Microstructural examination was performed by means of scanning electron microscopy (SEM) combined with the energy dispersive spectroscopy (EDS) mode of electron probe microanalysis (EPMA) and qualitative X-ray diffraction (XRD). The primary evolutionary trend observed was the tendency of Zr to gradually segregate as the temperature rises, while all the other elements eventually dissolve in the BCC solid solution phase once the onset of Laves phase complex decomposition is reached. The performed thermodynamic modelling was based on the Calculation of Phase Diagrams method (CALPHAD). The BCC A2 solid solution phase is predicted by the model to contain increasing amounts of Cr as the temperature rises, which is in perfect agreement with the actual results obtained by SEM. However, the model was not able to predict the existence of the Zr-rich phase or the tendency of Zr to segregate and form its own solid solution—most likely as a result of the Zr segregation trend not being an equilibrium phenomenon. PMID:29360763

Resonance strengths in the {sup 14}N(p,gamma){sup 15}O and {sup 15}N(p,alphagamma){sup 12}C reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marta, Michele; Trompler, Erik; Bemmerer, Daniel

2010-05-15

The {sup 14}N(p,gamma){sup 15}O reaction is the slowest reaction of the carbon-nitrogen-oxygen cycle of hydrogen burning in stars. As a consequence, it determines the rate of the cycle. The {sup 15}N(p,alphagamma){sup 12}C reaction is frequently used in inverse kinematics for hydrogen depth profiling in materials. The {sup 14}N(p,gamma){sup 15}O and {sup 15}N(p,alphagamma){sup 12}C reactions have been studied simultaneously, using titanium nitride targets of natural isotopic composition and a proton beam. The strengths of the resonances at E{sub p} = 1058 keV in {sup 14}N(p,gamma){sup 15}O and at E{sub p} = 897 and 430 keV in {sup 15}N(p,alphagamma){sup 12}C have beenmore » determined with improved precision, relative to the well-known resonance at E{sub p} = 278 keV in {sup 14}N(p,gamma){sup 15}O. The new recommended values are omegagamma=0.353+-0.018, 362+-20, and 21.9+-1.0 eV for their respective strengths. In addition, the branching ratios for the decay of the E{sub p} = 1058 keV resonance in {sup 14}N(p,gamma){sup 15}O have been redetermined. The data reported here should facilitate future studies of off-resonant capture in the {sup 14}N(p,gamma){sup 15}O reaction that are needed for an improved R-matrix extrapolation of the cross section. In addition, the data on the 430 keV resonance in {sup 15}N(p,alphagamma){sup 12}C may be useful for hydrogen depth profiling.« less

15 CFR Appendix C to Subpart G of... - Marine Conservation Area Boundary

Code of Federal Regulations, 2012 CFR

2012-01-01

... 15 Commerce and Foreign Trade 3 2012-01-01 2012-01-01 false Marine Conservation Area Boundary C... COASTAL RESOURCE MANAGEMENT NATIONAL MARINE SANCTUARY PROGRAM REGULATIONS Channel Islands National Marine Sanctuary Pt. 922, Subpt. G, App. C Appendix C to Subpart G of Part 922—Marine Conservation Area Boundary C...

15 CFR Appendix C to Subpart G of... - Marine Conservation Area Boundary

Code of Federal Regulations, 2014 CFR

2014-01-01

... 15 Commerce and Foreign Trade 3 2014-01-01 2014-01-01 false Marine Conservation Area Boundary C... COASTAL RESOURCE MANAGEMENT NATIONAL MARINE SANCTUARY PROGRAM REGULATIONS Channel Islands National Marine Sanctuary Pt. 922, Subpt. G, App. C Appendix C to Subpart G of Part 922—Marine Conservation Area Boundary C...

15 CFR Appendix C to Subpart G of... - Marine Conservation Area Boundary

Code of Federal Regulations, 2011 CFR

2011-01-01

... 15 Commerce and Foreign Trade 3 2011-01-01 2011-01-01 false Marine Conservation Area Boundary C... COASTAL RESOURCE MANAGEMENT NATIONAL MARINE SANCTUARY PROGRAM REGULATIONS Channel Islands National Marine Sanctuary Pt. 922, Subpt. G, App. C Appendix C to Subpart G of Part 922—Marine Conservation Area Boundary C...

15 CFR Appendix C to Subpart G of... - Marine Conservation Area Boundary

Code of Federal Regulations, 2013 CFR

2013-01-01

... 15 Commerce and Foreign Trade 3 2013-01-01 2013-01-01 false Marine Conservation Area Boundary C... COASTAL RESOURCE MANAGEMENT NATIONAL MARINE SANCTUARY PROGRAM REGULATIONS Channel Islands National Marine Sanctuary Pt. 922, Subpt. G, App. C Appendix C to Subpart G of Part 922—Marine Conservation Area Boundary C...

15 CFR Appendix C to Subpart G of... - Marine Conservation Area Boundary

Code of Federal Regulations, 2010 CFR

2010-01-01

... 15 Commerce and Foreign Trade 3 2010-01-01 2010-01-01 false Marine Conservation Area Boundary C... COASTAL RESOURCE MANAGEMENT NATIONAL MARINE SANCTUARY PROGRAM REGULATIONS Channel Islands National Marine Sanctuary Pt. 922, Subpt. G, App. C Appendix C to Subpart G of Part 922—Marine Conservation Area Boundary C...

Community climate simulations to assess avoided impacts in 1.5 and 2 °C futures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanderson, Benjamin M.; Xu, Yangyang; Tebaldi, Claudia

The Paris Agreement of December 2015 stated a goal to pursue efforts to keep global temperatures below 1.5 °C above preindustrial levels and well below 2 °C. The IPCC was charged with assessing climate impacts at these temperature levels, but fully coupled equilibrium climate simulations do not currently exist to inform such assessments. Here, we produce a set of scenarios using a simple model designed to achieve long-term 1.5 and 2 °C temperatures in a stable climate. These scenarios are then used to produce century-scale ensemble simulations using the Community Earth System Model, providing impact-relevant long-term climate data for stabilization pathways at 1.5 andmore » 2 °C levels and an overshoot 1.5 °C case, which are realized (for the 21st century) in the coupled model and are freely available to the community. We also describe the design of the simulations and a brief overview of their impact-relevant climate response. Exceedance of historical record temperature occurs with 60 % greater frequency in the 2 °C climate than in a 1.5 °C climate aggregated globally, and with twice the frequency in equatorial and arid regions. Extreme precipitation intensity is statistically significantly higher in a 2.0 °C climate than a 1.5 °C climate in some specific regions (but not all). The model exhibits large differences in the Arctic, which is ice-free with a frequency of 1 in 3 years in the 2.0 °C scenario, and 1 in 40 years in the 1.5 °C scenario. Significance of impact differences with respect to multi-model variability is not assessed.« less

Community climate simulations to assess avoided impacts in 1.5 and 2 °C futures

DOE PAGES

Sanderson, Benjamin M.; Xu, Yangyang; Tebaldi, Claudia; ...

2017-09-19

The Paris Agreement of December 2015 stated a goal to pursue efforts to keep global temperatures below 1.5 °C above preindustrial levels and well below 2 °C. The IPCC was charged with assessing climate impacts at these temperature levels, but fully coupled equilibrium climate simulations do not currently exist to inform such assessments. Here, we produce a set of scenarios using a simple model designed to achieve long-term 1.5 and 2 °C temperatures in a stable climate. These scenarios are then used to produce century-scale ensemble simulations using the Community Earth System Model, providing impact-relevant long-term climate data for stabilization pathways at 1.5 andmore » 2 °C levels and an overshoot 1.5 °C case, which are realized (for the 21st century) in the coupled model and are freely available to the community. We also describe the design of the simulations and a brief overview of their impact-relevant climate response. Exceedance of historical record temperature occurs with 60 % greater frequency in the 2 °C climate than in a 1.5 °C climate aggregated globally, and with twice the frequency in equatorial and arid regions. Extreme precipitation intensity is statistically significantly higher in a 2.0 °C climate than a 1.5 °C climate in some specific regions (but not all). The model exhibits large differences in the Arctic, which is ice-free with a frequency of 1 in 3 years in the 2.0 °C scenario, and 1 in 40 years in the 1.5 °C scenario. Significance of impact differences with respect to multi-model variability is not assessed.« less

15. Historic American Buildings Survey, Photocopy of c. 1905 photograph ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

15. Historic American Buildings Survey, Photocopy of c. 1905 photograph from the collection of Mr. Chester Williams, Rome, New York. - Barnes-Mudge House, 115 East Dominick Street, Rome, Oneida County, NY

Development of high strength ferritic steel for interconnect application in SOFCs

NASA Astrophysics Data System (ADS)

Froitzheim, J.; Meier, G. H.; Niewolak, L.; Ennis, P. J.; Hattendorf, H.; Singheiser, L.; Quadakkers, W. J.

High-Cr ferritic model steels containing various additions of the refractory elements Nb and/or W were studied with respect to oxidation behaviour (hot) tensile properties, creep behaviour and high-temperature electrical conductivity of the surface oxide scales. Whereas W additions of around 2 wt.% had hardly any effect on the oxidation rates at 800 and 900 °C, Nb additions of 1% led to a substantially enhanced growth rate of the protective surface oxide scale. It was found that this adverse effect can be alleviated by suitable Si additions. This is related to the incorporation of Si and Nb into Laves phase precipitates which also contribute to increased creep and hot tensile strength. The dispersion of Laves phase precipitates was greatly refined by combined additions of Nb and W. The high-temperature electrical conductivity of the surface oxide scales was similar to that of the Nb/W-free alloys. Thus the combined additions of Nb, W and Si resulted in an alloy with oxidation resistance, ASR contribution and thermal expansion comparable to the commercial alloy Crofer 22 APU, but with creep strength far greater than that of Crofer 22 APU.

Non-Toxic, Non-Flammable, -80 C Phase Change Materials

NASA Technical Reports Server (NTRS)

Cutbirth, J. Michael

2013-01-01

The objective of this effort was to develop a non-toxic, non-flammable, -80 C phase change material (PCM) to be used in NASA's ICEPAC capsules for biological sample preservation in flight to and from Earth orbit. A temperature of about -68 C or lower is a critical temperature for maintaining stable cell, tissue, and cell fragment storage.

Biogeochemical potential of biomass pyrolysis systems for limiting global warming to 1.5 °C

NASA Astrophysics Data System (ADS)

Werner, C.; Schmidt, H.-P.; Gerten, D.; Lucht, W.; Kammann, C.

2018-04-01

Negative emission (NE) technologies are recognized to play an increasingly relevant role in strategies limiting mean global warming to 1.5 °C as specified in the Paris Agreement. The potentially significant contribution of pyrogenic carbon capture and storage (PyCCS) is, however, highly underrepresented in the discussion. In this study, we conduct the first quantitative assessment of the global potential of PyCCS as a NE technology based on biomass plantations. Using a process-based biosphere model, we calculate the land use change required to reach specific climate mitigation goals while observing biodiversity protection guardrails. We consider NE targets of 100–300 GtC following socioeconomic pathways consistent with a mean global warming of 1.5 °C as well as the option of additional carbon balancing required in case of failure or delay of decarbonization measures. The technological opportunities of PyCCS are represented by three tracks accounting for the sequestration of different pyrolysis products: biochar (as soil amendment), bio-oil (pumped into geological storages) and permanent-pyrogas (capture and storage of CO2 from gas combustion). In addition, we analyse how the gain in land induced by biochar-mediated yield increases on tropical cropland may reduce the pressure on land. Our results show that meeting the 1.5 °C goal through mitigation strategies including large-scale NE with plantation-based PyCCS may require conversion of natural vegetation to biomass plantations in the order of 133–3280 Mha globally, depending on the applied technology and the NE demand. Advancing towards additional bio-oil sequestration reduces land demand considerably by potentially up to 60%, while the benefits from yield increases account for another 3%–38% reduction (equalling 82–362 Mha). However, when mitigation commitments are increased by high balancing claims, even the most advanced PyCCS technologies and biochar-mediated co-benefits cannot compensate for

Vulnerabilities and resilience of European power generation to 1.5 °C, 2 °C and 3 °C warming

NASA Astrophysics Data System (ADS)

Tobin, I.; Greuell, W.; Jerez, S.; Ludwig, F.; Vautard, R.; van Vliet, M. T. H.; Bréon, F.-M.

2018-04-01

The electricity sector is currently considered mainly on the emission side of the climate change equation. In order to limit climate warming to below 2 °C, or even 1.5 °C, it must undergo a rapid transition towards carbon neutral production by the mid-century. Simultaneously, electricity generating technologies will be vulnerable to climate change. Here, we assess the impacts of climate change on wind, solar photovoltaic, hydro and thermoelectric power generation in Europe using a consistent modelling approach across the different technologies. We compare the impacts for different global warming scenarios: +1.5 °C, +2 °C and +3 °C. Results show that climate change has negative impacts on electricity production in most countries and for most technologies. Such impacts remain limited for a 1.5 °C warming, and roughly double for a 3 °C warming. Impacts are relatively limited for solar photovoltaic and wind power potential which may reduce up to 10%, while hydropower and thermoelectric generation may decrease by up to 20%. Generally, impacts are more severe in southern Europe than in northern Europe, inducing inequity between EU countries. We show that a higher share of renewables could reduce the vulnerability of power generation to climate change, although the variability of wind and solar PV production remains a significant challenge.

15. Photocopy of photograph (original in WACC), photographer unknown, c. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

15. Photocopy of photograph (original in WACC), photographer unknown, c. 1917 BEN ERICKSON IN WWI UNIFORM STANDING IN FRONT OF SOUTH LIVING ROOM WINDOW (ADOBE WALLS) - Faraway Ranch, Willcox, Cochise County, AZ

C-O volatiles in Apollo 15 and Apollo 17 picritic glasses

NASA Technical Reports Server (NTRS)

Rutherford, Malcolm J.; Fogel, Robert A.

1993-01-01

A15 and A17 primitive picritic glasses have been examined by FTIR for the presence of dissolved C-O species to determine the role of C-O gasses on driving lunar fire-fountains. A15 green and yellow glasses were extensively studied and found to be free of dissolved C species down to FTIR detection limits (10-100 ppm; species and sample specific). Preliminary data on A17 orange glasses are similarly devoid of FTIR detectable C-O species. Re-analyses of the C-O driving mechanism theory for mare volcanism demonstrates the need to determine the fO2 of the lunar interior; the factor that most critically determined the role of C gasses in the fire-fountaining events. Oxygen fugacities equivalent to IW-0.5 and above imply dissolved CO3(=) in the primitive glasses at levels above FTIR detection. The f02's below IW-0.5 imply concentrations of CO3(=) below FTIR detection. Recent data suggesting lunar mantle fO2's of IW-2 or less, strongly mitigate against finding FTIR measurable dissolved CO3(=) consistent with the findings of this study.

The evaluation of a new method to extract spectroscopic factors using asymptotic normalization coefficients and the astrophysical ^14C(n,γ)^15C reaction rate

NASA Astrophysics Data System (ADS)

McCleskey, M.; Mukhamedzhanov, A. M.; Trache, L.; Banu, A.; Goldberg, V.; Roeder, B. T.; Simmons, E. N.; Spiridon, A.; Tribble, R. E.

2011-10-01

A new method to determine spectroscopic factors (SFs) that utilizes asymptotic normalization coefficients (ANCs) has been tested at Texas A&M, using ^15C as a test case. The method would use the ANC to fix the external contribution to a non-peripheral reaction which would otherwise be free to vary to unphysical values in a traditional approach. The investigation consisted of two parts. First, the ANC for the ^14C+n configuration in ^15C was determined from the heavy ion neutron transfer reaction ^13C(^14C,^15C)^12C and the inverse kinematics reaction d(^14C,p)^15C. Both of these reactions were measured at sufficiently low energy to be peripheral. Next, a non-peripheral reaction ^14C(d,p)^15C was measured with an incident deuteron energy of 60 MeV, and this reaction was used along with the previously determined ANC to attempt to find the SF. The ANC was also used to calculate the astrophysical neutron direct capture rate for ^14C(n,γ)^15C, which was compared with recent direct experimental results.

Scenario dependence of future changes in climate extremes under 1.5 °C and 2 °C global warming

PubMed Central

Wang, Zhili; Lin, Lei; Zhang, Xiaoye; Zhang, Hua; Liu, Liangke; Xu, Yangyang

2017-01-01

The 2015 Paris Agreement aims to limit global warming below 2 °C and pursue efforts to even limit it to 1.5 °C relative to pre-industrial levels. Decision makers need reliable information on the impacts caused by these warming levels for climate mitigation and adaptation measures. We explore the changes in climate extremes, which are closely tied to economic losses and casualties, under 1.5 °C and 2 °C global warming and their scenario dependence using three sets of ensemble global climate model simulations. A warming of 0.5 °C (from 1.5 °C to 2 °C) leads to significant increases in temperature and precipitation extremes in most regions. However, the projected changes in climate extremes under both warming levels highly depend on the pathways of emissions scenarios, with different greenhouse gas (GHG)/aerosol forcing ratio and GHG levels. Moreover, there are multifold differences in several heavily polluted regions, among the scenarios, in the changes in precipitation extremes due to an additional 0.5 °C warming from 1.5 °C to 2 °C. Our results demonstrate that the chemical compositions of emissions scenarios, not just the total radiative forcing and resultant warming level, must be considered when assessing the impacts of global 1.5/2 °C warming. PMID:28425445

Internal variability in European summer temperatures at 1.5 °C and 2 °C of global warming

NASA Astrophysics Data System (ADS)

Suarez-Gutierrez, Laura; Li, Chao; Müller, Wolfgang A.; Marotzke, Jochem

2018-06-01

We use the 100-member Grand Ensemble with the climate model MPI-ESM to evaluate the controllability of mean and extreme European summer temperatures with the global mean temperature targets in the Paris Agreement. We find that European summer temperatures at 2 °C of global warming are on average 1 °C higher than at 1.5 °C of global warming with respect to pre-industrial levels. In a 2 °C warmer world, one out of every two European summer months would be warmer than ever observed in our current climate. Daily maximum temperature anomalies for extreme events with return periods of up to 500 years reach return levels of 7 °C at 2 °C of global warming and 5.5 °C at 1.5 °C of global warming. The largest differences in return levels for shorter return periods of 20 years are over southern Europe, where we find the highest mean temperature increase. In contrast, for events with return periods of over 100 years these differences are largest over central Europe, where we find the largest changes in temperature variability. However, due to the large effect of internal variability, only four out of every ten summer months in a 2 °C warmer world present mean temperatures that could be distinguishable from those in a 1.5 °C world. The distinguishability between the two climates is largest over southern Europe, while decreasing to around 10% distinguishable months over eastern Europe. Furthermore, we find that 10% of the most extreme and severe summer maximum temperatures in a 2 °C world could be avoided by limiting global warming to 1.5 °C.

Late Holocene monsoon climate of northeastern Taiwan inferred from elemental (C, N) and isotopic (δ13C, δ15N) data in lake sediments

NASA Astrophysics Data System (ADS)

Selvaraj, Kandasamy; Wei, Kuo-Yen; Liu, Kon-Kee; Kao, Shuh-Ji

2012-03-01

Little information exists about centennial-scale climate variability on oceanic islands in the western Pacific where the East Asian monsoon (EAM) strongly influences the climate, mountain ecosystem and the society. In this study, we investigate a 168 cm long sediment core recovered from Emerald Peak Lake in subalpine NE Taiwan for the contents of grain size, total organic carbon (TOC), C/N ratio, and stable isotopes (δ13C and δ15N) to reconstruct the monsoon climate and vegetation density during the late Holocene. Six radiocarbon (14C) ages obtained on plant remains used for the chronology indicate that the sediment core has been accumulated since ˜3770 cal BP with a mean sedimentation rate of 44.6 cm/ka. The sub-centennial resolution of our proxy records reveals strong fluctuations of the EAM and vegetation density for the past ˜3770 cal BP. The greater contents of coarse and medium sediments with overall decreasing trends from 3770 to 2000 cal BP suggest an increasing fine sediment influx from the catchment likely due to an increasing lake water level. Although low TOC content, C/N ratio, and enriched δ13C values in bulk and fine sediments during this interval suggest a sparsely vegetated catchment, increasing trends of TOC content and C/N ratio together with decreasing trends of δ13C and δ15N values indicate a strengthening pattern of summer monsoon. This is in contrast to a decreasing monsoon strength inferred from Dongge Cave δ18O record at that time, supporting the idea of anti-phasing of summer EAM and Indian summer monsoon. Since 2000 cal BP, higher content of fine sediments with high TOC content and C/N ratio but relatively depleted δ13C and low δ15N values suggest a high but stable lake water level and dense C3 plants, consistent with a stronger summer monsoon in a wet climate. Within this general trend, we interpret a prominent change of proxy parameters in sediments from ˜560 to 150 cal BP, as subtropical evidence for the Little Ice Age in NE

SPIRITS 15c and SPIRITS 14buu: Two Obscured Supernovae in the Nearby Star-forming Galaxy IC 2163

NASA Astrophysics Data System (ADS)

Jencson, Jacob E.; Kasliwal, Mansi M.; Johansson, Joel; Contreras, Carlos; Castellón, Sergio; Bond, Howard E.; Monson, Andrew J.; Masci, Frank J.; Cody, Ann Marie; Andrews, Jennifer E.; Bally, John; Cao, Yi; Fox, Ori D.; Gburek, Timothy; Gehrz, Robert D.; Green, Wayne; Helou, George; Hsiao, Eric; Morrell, Nidia; Phillips, Mark; Prince, Thomas A.; Simcoe, Robert A.; Smith, Nathan; Tinyanont, Samaporn; Williams, Robert

2017-03-01

SPitzer InfraRed Intensive Transients Survey—SPIRITS—is an ongoing survey of nearby galaxies searching for infrared (IR) transients with Spitzer/IRAC. We present the discovery and follow-up observations of one of our most luminous (M [4.5] = -17.1 ± 0.4 mag, Vega) and reddest ([3.6] - [4.5] = 3.0 ± 0.2 mag) transients, SPIRITS 15c. The transient was detected in a dusty spiral arm of IC 2163 (D ≈ 35.5 Mpc). Pre-discovery ground-based imaging revealed an associated, shorter-duration transient in the optical and near-IR (NIR). NIR spectroscopy showed a broad (≈8400 km s-1), double-peaked emission line of He I at 1.083 μm, indicating an explosive origin. The NIR spectrum of SPIRITS 15c is similar to that of the Type IIb SN 2011dh at a phase of ≈200 days. Assuming an A V = 2.2 mag of extinction in SPIRITS 15c provides a good match between their optical light curves. The NIR light curves, however, show some minor discrepancies when compared with SN 2011dh, and the extreme [3.6]-[4.5] color has not been previously observed for any SN IIb. Another luminous (M 4.5 = -16.1 ± 0.4 mag) event, SPIRITS 14buu, was serendipitously discovered in the same galaxy. The source displays an optical plateau lasting ≳80 days, and we suggest a scenario similar to the low-luminosity Type IIP SN 2005cs obscured by A V ≈ 1.5 mag. Other classes of IR-luminous transients can likely be ruled out in both cases. If both events are indeed SNe, this may suggest that ≳18% of nearby core-collapse SNe are missed by currently operating optical surveys.

Ultra-fine grained microstructure of metastable beta Ti-15Mo alloy and its effects on the phase transformations

NASA Astrophysics Data System (ADS)

Václavová, K.; Stráský, J.; Zháňal, P.; Veselý, J.; Polyakova, V.; Semenova, I.; Janeček, M.

2017-05-01

Processing of metastable titanium alloys by severe plastic deformation provides an opportunity to achieve exceptional grain refinement, to enhance the strength and to affect phase transformations occurring during thermal treatment. The main aim of this study is to investigate the microstructure of ultra-fine grained (UFG) material and effect of microstructural changes on phase transformations in metastable β-Ti alloy Ti-15Mo. Metastable β-Ti alloys are currently the most studied Ti-based materials with prospective use in medicine. Ti-15Mo alloy after solution treatment contains metastable β-phase. Metastable ω-phase and stable α-phase particles are formed upon annealing,. Solution treated Ti-15Mo alloy was deformed by high pressure torsion (HPT) at room temperature. Severely deformed structure after HPT with grain size of ~200 nm was studied by transmission electron microscopy. In-situ electrical resistance measurements showed significant changes in undergoing phase transformations when compared to coarse-grained (CG) material. Scanning electron microscopy revealed heterogeneous precipitation of α-particles at grain boundaries (GB). Due to the high density of GBs in UFG structure, these precipitates are very fine and equiaxed. The study demonstrates that SPD is capable of enhancing mechanical properties due to grain refinement and via affecting precipitation processes in metastable β-Ti alloys.

The Inequality of Climate Change From 1.5 to 2°C of Global Warming

NASA Astrophysics Data System (ADS)

King, Andrew D.; Harrington, Luke J.

2018-05-01

The Paris Agreement aims to keep global warming well below 2°C above preindustrial levels with a preferred ambitious 1.5°C target. Developing countries, especially small island nations, pressed for the 1.5°C target to be adopted, but who will suffer the largest changes in climate if we miss this target? Here we show that exceeding the 1.5°C global warming target would lead to the poorest experiencing the greatest local climate changes. Under these circumstances greater support for climate adaptation to prevent poverty growth would be required.

Influence of Alloy Content and Prior Microstructure on Evolution of Secondary Phases in Weldments of 9Cr-Reduced Activation Ferritic-Martensitic Steel

NASA Astrophysics Data System (ADS)

Thomas Paul, V.; Sudha, C.; Saroja, S.

2015-08-01

9Cr-Reduced Activation Ferritic-Martensitic steels with 1 and 1.4 wt pct tungsten are materials of choice for the test blanket module in fusion reactors. The steels possess a tempered martensite microstructure with a decoration of inter- and intra-lath carbides, which undergoes extensive modification on application of heat. The change in substructure and precipitation behavior on welding and subsequent thermal exposure has been studied using both experimental and computational techniques. Changes i.e., formation of various phases, their volume fraction, size, and morphology in different regions of the weldment due to prolonged thermal exposure was influenced not only by the time and temperature of exposure but also the prior microstructure. Laves phase of type Fe2W was formed in the high tungsten steel, on aging the weldment at 823 K (550 °C). It formed in the fine-grained heat-affected zone (HAZ) at much shorter durations than in the base metal. The accelerated kinetics has been understood in terms of enhanced precipitation of carbides at lath/grain boundaries during aging and the concomitant depletion of carbon and chromium and enrichment of tungsten in the vicinity of the carbides. Therefore, the fine-grained HAZ in the weldment was identified as a region susceptible for failure during service.

(13)C-(15)N correlation via unsymmetrical indirect covariance NMR: application to vinblastine.

PubMed

Martin, Gary E; Hilton, Bruce D; Blinov, Kirill A; Williams, Antony J

2007-12-01

Unsymmetrical indirect covariance processing methods allow the derivation of hyphenated 2D NMR data from the component 2D spectra, potentially circumventing the acquisition of the much lower sensitivity hyphenated 2D NMR experimental data. Calculation of HSQC-COSY and HSQC-NOESY spectra from GHSQC, COSY, and NOESY spectra, respectively, has been reported. The use of unsymmetrical indirect covariance processing has also been applied to the combination of (1)H- (13)C GHSQC and (1)H- (15)N long-range correlation data (GHMBC, IMPEACH, or CIGAR-HMBC). The application of unsymmetrical indirect covariance processing to spectra of vinblastine is now reported, specifically the algorithmic extraction of (13)C- (15)N correlations via the unsymmetrical indirect covariance processing of the combination of (1)H- (13)C GHSQC and long-range (1)H- (15)N GHMBC to produce the equivalent of a (13)C- (15)N HSQC-HMBC correlation spectrum. The elimination of artifact responses with aromatic solvent-induced shifts (ASIS) is shown in addition to a method of forecasting potential artifact responses through the indirect covariance processing of the GHSQC spectrum used in the unsymmetrical indirect covariance processing.

Phase stability limit of c-BN under hydrostatic and non-hydrostatic pressure conditions

NASA Astrophysics Data System (ADS)

Xiao, Jianwei; Du, Jinglian; Wen, Bin; Melnik, Roderick; Kawazoe, Yoshiyuki; Zhang, Xiangyi

2014-04-01

Phase stability limit of cubic boron nitride (c-BN) has been investigated by the crystal structure search technique. It indicated that this limit is ˜1000 GPa at hydrostatic pressure condition. Above this pressure, c-BN turns into a metastable phase with respect to rocksalt type boron nitride (rs-BN). However, rs-BN cannot be retained at 0 GPa owing to its instability at pressure below 250 GPa. For non-hydrostatic pressure conditions, the phase stability limit of c-BN is substantially lower than that under hydrostatic pressure conditions and it is also dramatically different for other pressure mode.

Phase stability limit of c-BN under hydrostatic and non-hydrostatic pressure conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, Jianwei; Du, Jinglian; Wen, Bin, E-mail: wenbin@ysu.edu.cn

2014-04-28

Phase stability limit of cubic boron nitride (c-BN) has been investigated by the crystal structure search technique. It indicated that this limit is ∼1000 GPa at hydrostatic pressure condition. Above this pressure, c-BN turns into a metastable phase with respect to rocksalt type boron nitride (rs-BN). However, rs-BN cannot be retained at 0 GPa owing to its instability at pressure below 250 GPa. For non-hydrostatic pressure conditions, the phase stability limit of c-BN is substantially lower than that under hydrostatic pressure conditions and it is also dramatically different for other pressure mode.

Differential climate impacts for policy-relevant limits to global warming: the case of 1.5 °C and 2 °C

NASA Astrophysics Data System (ADS)

Schleussner, Carl-Friedrich; Lissner, Tabea K.; Fischer, Erich M.; Wohland, Jan; Perrette, Mahé; Golly, Antonius; Rogelj, Joeri; Childers, Katelin; Schewe, Jacob; Frieler, Katja; Mengel, Matthias; Hare, William; Schaeffer, Michiel

2016-04-01

Robust appraisals of climate impacts at different levels of global-mean temperature increase are vital to guide assessments of dangerous anthropogenic interference with the climate system. The 2015 Paris Agreement includes a two-headed temperature goal: "holding the increase in the global average temperature to well below 2 °C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 °C". Despite the prominence of these two temperature limits, a comprehensive overview of the differences in climate impacts at these levels is still missing. Here we provide an assessment of key impacts of climate change at warming levels of 1.5 °C and 2 °C, including extreme weather events, water availability, agricultural yields, sea-level rise and risk of coral reef loss. Our results reveal substantial differences in impacts between a 1.5 °C and 2 °C warming that are highly relevant for the assessment of dangerous anthropogenic interference with the climate system. For heat-related extremes, the additional 0.5 °C increase in global-mean temperature marks the difference between events at the upper limit of present-day natural variability and a new climate regime, particularly in tropical regions. Similarly, this warming difference is likely to be decisive for the future of tropical coral reefs. In a scenario with an end-of-century warming of 2 °C, virtually all tropical coral reefs are projected to be at risk of severe degradation due to temperature-induced bleaching from 2050 onwards. This fraction is reduced to about 90 % in 2050 and projected to decline to 70 % by 2100 for a 1.5 °C scenario. Analyses of precipitation-related impacts reveal distinct regional differences and hot-spots of change emerge. Regional reduction in median water availability for the Mediterranean is found to nearly double from 9 % to 17 % between 1.5 °C and 2 °C, and the projected lengthening of regional dry spells increases from 7 to 11 %. Projections for

Solid Phase Characterization of Tank 241-C-105 Grab Samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ely, T. M.; LaMothe, M. E.; Lachut, J. S.

The solid phase characterization (SPC) of three grab samples from single-shell Tank 241-C-105 (C-105) that were received at the laboratory the week of October 26, 2015, has been completed. The three samples were received and broken down in the 11A hot cells.

In situ Observation of Phase Transformation in MnAl(C) Magnetic Materials

PubMed Central

Si, Ping-Zhan; Qian, Hui-Dong; Choi, Chul-Jin; Park, Jihoon; Han, Sangho; Ge, Hong-Liang; Shinde, Kiran P.

2017-01-01

The phase transformation in two modes, including both displacive and massive growth of τ-phase from ε-MnAl(C), was observed by in situ transmission electron microscopy. The exact temperature range for different phase transformation modes was determined by magnetic measurements. The displacive growth of ε→τ in Mn54Al46 (or Mn54Al46C2.44) occurs at temperatures below 650 K (or 766 K), above which both modes coexist. One-third or less of the ε-phase can be transformed into τ-phase via displacive mode while the remaining two-thirds or more via massive mode. In bulk τ-phase, most τ-nanocrystals formed via displacive mode are distributed in the matrix of large τ-grains that formed via massive mode. The typical massive growth rate of the τ-phase is 8–60 nm/s, while the displacive growth rate is low. A more complete understanding of the ε→τ phase transformations in the MnAl-based magnets was provided in this work, based on which the annealing process for ε→τ was optimized and thus high purity τ-phase with high saturation magnetization was obtained. PMID:28858231

Differentiation of Pigment in Eggs Using Carbon ((13)C/(12)C) and Nitrogen ((15)N/(14)N) Stable Isotopes.

PubMed

Sun, Feng M; Shi, Guang Y; Wang, Hui W

2016-07-01

Consumers prefer natural and healthy food, but artificial pigments are often abused in egg products. The study aimed at differentiating the origin of pigments in eggs by applying the technique of carbon ((13)C/(12)C) and nitrogen ((15)N/(14)N) stable isotope analysis. Five hundred sixty laying hens were randomly distributed into 14 treatments, which were divided into four groups: maize, carophyll red pigment, carophyll yellow pigment, and a mixture of carophyll red and yellow pigments. Eggs were collected and pretreated to determe the values of the Roche Yolk Color Fan (RCF), δ(13)C, and δ(15)N. With increasing maize content, the RCF and δ(13)C values of yolks increased. Moreover, the RCF values in the three pigment groups were significantly influenced by the artificial colors, but δ(13)C values were not significantly different, regardless of the existence of pigment. The δ(15)N values in all treatments did not vary as regularly as the carbon stable isotope. A strong positive correlation was found between RCF and δ(13)C in the maize group, but no such correlation was be observed in the pigment groups. It is concluded that carbon stable isotope ratio analysis (δ(13)C) of the yolk can be used to differentiate the origin of the pigment added to eggs.

The Pneumococcal Serotype 15C Capsule Is Partially O-Acetylated and Allows for Limited Evasion of 23-Valent Pneumococcal Polysaccharide Vaccine-Elicited Anti-Serotype 15B Antibodies

PubMed Central

Spencer, Brady L.; Shenoy, Anukul T.; Orihuela, Carlos J.

2017-01-01

ABSTRACT As a species, Streptococcus pneumoniae (the pneumococcus) utilizes a diverse array of capsular polysaccharides to evade the host. In contrast to large variations in sugar composition and linkage formation, O-acetylation is a subtle capsular modification that nonetheless has a large impact on capsular shielding and recognition of the capsule by vaccine-elicited antibodies. Serotype 15B, which is included in the 23-valent pneumococcal polysaccharide vaccine (PPV23), carries the putative O-acetyltransferase gene wciZ. The coding sequence of wciZ contains eight consecutive TA repeats [(TA)8]. Replication slippage is thought to result in the addition or loss of TA repeats, subsequently causing frameshift and truncation of WciZ to yield a nonacetylated serotype, 15C. Using sensitive serological tools, we show that serotype 15C isolates whose wciZ contains seven or nine TA repeats retain partial O-acetylation, while serotype 15C isolates whose wciZ contains six TA repeats have barely detectable O-acetylation. We confirmed by inhibition enzyme-linked immunosorbent assay that (TA)7 serotype 15C is ∼0.1% as acetylated as serotype 15B, while serotype 15X is nonacetylated. To eliminate the impact of genetic background, we created isogenic serotype 15B, (TA)7 serotype 15C, and 15BΔwciZ (15X) strains and found that reduction or absence of WciZ-mediated O-acetylation did not affect capsular shielding from phagocytes, biofilm formation, adhesion to nasopharyngeal cells, desiccation tolerance, or murine colonization. Sera from PPV23-immunized persons opsonized serotype 15B significantly but only slightly better than serotypes 15C and 15X; thus, PPV23 may not result in expansion of serotype 15C. PMID:28637806

The Pneumococcal Serotype 15C Capsule Is Partially O-Acetylated and Allows for Limited Evasion of 23-Valent Pneumococcal Polysaccharide Vaccine-Elicited Anti-Serotype 15B Antibodies.

PubMed

Spencer, Brady L; Shenoy, Anukul T; Orihuela, Carlos J; Nahm, Moon H

2017-08-01

As a species, Streptococcus pneumoniae (the pneumococcus) utilizes a diverse array of capsular polysaccharides to evade the host. In contrast to large variations in sugar composition and linkage formation, O-acetylation is a subtle capsular modification that nonetheless has a large impact on capsular shielding and recognition of the capsule by vaccine-elicited antibodies. Serotype 15B, which is included in the 23-valent pneumococcal polysaccharide vaccine (PPV23), carries the putative O-acetyltransferase gene wciZ The coding sequence of wciZ contains eight consecutive TA repeats [(TA) 8 ]. Replication slippage is thought to result in the addition or loss of TA repeats, subsequently causing frameshift and truncation of WciZ to yield a nonacetylated serotype, 15C. Using sensitive serological tools, we show that serotype 15C isolates whose wciZ contains seven or nine TA repeats retain partial O-acetylation, while serotype 15C isolates whose wciZ contains six TA repeats have barely detectable O-acetylation. We confirmed by inhibition enzyme-linked immunosorbent assay that (TA) 7 serotype 15C is ∼0.1% as acetylated as serotype 15B, while serotype 15X is nonacetylated. To eliminate the impact of genetic background, we created isogenic serotype 15B, (TA) 7 serotype 15C, and 15BΔ wciZ (15X) strains and found that reduction or absence of WciZ-mediated O-acetylation did not affect capsular shielding from phagocytes, biofilm formation, adhesion to nasopharyngeal cells, desiccation tolerance, or murine colonization. Sera from PPV23-immunized persons opsonized serotype 15B significantly but only slightly better than serotypes 15C and 15X; thus, PPV23 may not result in expansion of serotype 15C. Copyright © 2017 American Society for Microbiology.

The CN/C15N isotopic ratio towards dark clouds

NASA Astrophysics Data System (ADS)

Hily-Blant, P.; Pineau des Forêts, G.; Faure, A.; Le Gal, R.; Padovani, M.

2013-09-01

Understanding the origin of the composition of solar system cosmomaterials is a central question, not only in the cosmochemistry and astrochemistry fields, and requires various approaches to be combined. Measurements of isotopic ratios in cometary materials provide strong constraints on the content of the protosolar nebula. Their relation with the composition of the parental dark clouds is, however, still very elusive. In this paper, we bring new constraints based on the isotopic composition of nitrogen in dark clouds, with the aim of understanding the chemical processes that are responsible for the observed isotopic ratios. We have observed and detected the fundamental rotational transition of C15N towards two starless dark clouds, L1544 and L1498. We were able to derive the column density ratio of C15N over 13CN towards the same clouds and obtain the CN/C15N isotopic ratios, which were found to be 500 ± 75 for both L1544 and L1498. These values are therefore marginally consistent with the protosolar value of 441. Moreover, this ratio is larger than the isotopic ratio of nitrogen measured in HCN. In addition, we present model calculations of the chemical fractionation of nitrogen in dark clouds, which make it possible to understand how CN can be deprived of 15N and HCN can simultaneously be enriched in heavy nitrogen. The non-fractionation of N2H+, however, remains an open issue, and we propose some chemical way of alleviating the discrepancy between model predictions and the observed ratios. Appendices are available in electronic form at http://www.aanda.orgThe reduced spectra (in FITS format) are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/557/A65

Projected Changes in the Asian-Australian Monsoon Region in 1.5°C and 2.0°C Global-Warming Scenarios

NASA Astrophysics Data System (ADS)

Chevuturi, Amulya; Klingaman, Nicholas P.; Turner, Andrew G.; Hannah, Shaun

2018-03-01

In light of the Paris Agreement, it is essential to identify regional impacts of half a degree additional global warming to inform climate adaptation and mitigation strategies. We investigate the effects of 1.5°C and 2.0°C global warming above preindustrial conditions, relative to present day (2006-2015), over the Asian-Australian monsoon region (AAMR) using five models from the Half a degree Additional warming, Prognosis and Projected Impacts (HAPPI) project. There is considerable intermodel variability in projected changes to mean climate and extreme events in 2.0°C and 1.5°C scenarios. There is high confidence in projected increases to mean and extreme surface temperatures over AAMR, as well as more-frequent persistent daily temperature extremes over East Asia, Australia, and northern India with an additional 0.5°C warming, which are likely to occur. Mean and extreme monsoon precipitation amplify over AAMR, except over Australia at 1.5°C where there is uncertainty in the sign of the change. Persistent daily extreme precipitation events are likely to become more frequent over parts of East Asia and India with an additional 0.5°C warming. There is lower confidence in projections of precipitation change than in projections of surface temperature change. These results highlight the benefits of limiting the global-mean temperature change to 1.5°C above preindustrial, as the severity of the above effects increases with an extra 0.5°C warming.

Survival and growth of foodborne pathogens in minimally processed vegetables at 4 and 15 °C.

PubMed

Tian, Jun-Qi; Bae, Young-Min; Choi, Na-Young; Kang, Dong-Hyun; Heu, Sunggi; Lee, Sun-Young

2012-01-01

We conducted this study to investigate the survival and growth of pathogens on fresh vegetables stored at 4 and 15 °C. Vegetables (romaine lettuce, iceberg lettuce, perilla leaves, and sprouts) were inoculated with 4 pathogens (Salmonella enterica serovar Typhimurium, Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli O157:H7) and stored at 2 different temperatures for different periods of time (3, 6, 9, 12, and 15 d at 4 °C and 1, 2, 3, 5, and 7 d at 15 °C). Populations of the 4 pathogens tended to increase on all vegetables stored at 15 °C for 7 d. Populations of E. coli O157:H7 and S. Typhimurium increased significantly, by approximately 2 log₁₀ CFU/g, on loose and head lettuce stored at 15 °C for 1 d. No significant differences were observed in the growth of different pathogens on vegetables stored at 4 °C for 15 d. E. coli O157:H7 did not survive on sprouts stored at 15 or 4 °C. The survival and growth of food pathogens on fresh vegetables were very different depending on the pathogen type and storage temperature. Survivals and growth of pathogens on various vegetables at 4 and 15 °C were observed in this study. Survivals and growth of pathogens on vegetables were different depending on the pathogen type and storage temperature. Therefore, vegetables should be stored under refrigerated conditions (below 4 °C) prior to consumption. This recommendation may vary depending on the type of vegetable. © 2011 Institute of Food Technologists®

Climate extremes, land–climate feedbacks and land-use forcing at 1.5°C

PubMed Central

Wartenburger, Richard; Guillod, Benoit P.; Hirsch, Annette L.; Vogel, Martha M.; Brovkin, Victor; van Vuuren, Detlef P.; Schaller, Nathalie; Boysen, Lena; Calvin, Katherine V.; Doelman, Jonathan; Greve, Peter; Havlik, Petr; Humpenöder, Florian; Krisztin, Tamas; Mitchell, Daniel; Popp, Alexander; Riahi, Keywan; Rogelj, Joeri; Schleussner, Carl-Friedrich; Sillmann, Jana; Stehfest, Elke

2018-01-01

This article investigates projected changes in temperature and water cycle extremes at 1.5°C of global warming, and highlights the role of land processes and land-use changes (LUCs) for these projections. We provide new comparisons of changes in climate at 1.5°C versus 2°C based on empirical sampling analyses of transient simulations versus simulations from the ‘Half a degree Additional warming, Prognosis and Projected Impacts’ (HAPPI) multi-model experiment. The two approaches yield similar overall results regarding changes in climate extremes on land, and reveal a substantial difference in the occurrence of regional extremes at 1.5°C versus 2°C. Land processes mediated through soil moisture feedbacks and land-use forcing play a major role for projected changes in extremes at 1.5°C in most mid-latitude regions, including densely populated areas in North America, Europe and Asia. This has important implications for low-emissions scenarios derived from integrated assessment models (IAMs), which include major LUCs in ambitious mitigation pathways (e.g. associated with increased bioenergy use), but are also shown to differ in the simulated LUC patterns. Biogeophysical effects from LUCs are not considered in the development of IAM scenarios, but play an important role for projected regional changes in climate extremes, and are thus of high relevance for sustainable development pathways. This article is part of the theme issue ‘The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'. PMID:29610382

Climate extremes, land-climate feedbacks and land-use forcing at 1.5°C.

PubMed

Seneviratne, Sonia I; Wartenburger, Richard; Guillod, Benoit P; Hirsch, Annette L; Vogel, Martha M; Brovkin, Victor; van Vuuren, Detlef P; Schaller, Nathalie; Boysen, Lena; Calvin, Katherine V; Doelman, Jonathan; Greve, Peter; Havlik, Petr; Humpenöder, Florian; Krisztin, Tamas; Mitchell, Daniel; Popp, Alexander; Riahi, Keywan; Rogelj, Joeri; Schleussner, Carl-Friedrich; Sillmann, Jana; Stehfest, Elke

2018-05-13

This article investigates projected changes in temperature and water cycle extremes at 1.5°C of global warming, and highlights the role of land processes and land-use changes (LUCs) for these projections. We provide new comparisons of changes in climate at 1.5°C versus 2°C based on empirical sampling analyses of transient simulations versus simulations from the 'Half a degree Additional warming, Prognosis and Projected Impacts' (HAPPI) multi-model experiment. The two approaches yield similar overall results regarding changes in climate extremes on land, and reveal a substantial difference in the occurrence of regional extremes at 1.5°C versus 2°C. Land processes mediated through soil moisture feedbacks and land-use forcing play a major role for projected changes in extremes at 1.5°C in most mid-latitude regions, including densely populated areas in North America, Europe and Asia. This has important implications for low-emissions scenarios derived from integrated assessment models (IAMs), which include major LUCs in ambitious mitigation pathways (e.g. associated with increased bioenergy use), but are also shown to differ in the simulated LUC patterns. Biogeophysical effects from LUCs are not considered in the development of IAM scenarios, but play an important role for projected regional changes in climate extremes, and are thus of high relevance for sustainable development pathways.This article is part of the theme issue 'The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'. © 2018 The Authors.

Climate extremes, land-climate feedbacks and land-use forcing at 1.5°C

NASA Astrophysics Data System (ADS)

Seneviratne, Sonia I.; Wartenburger, Richard; Guillod, Benoit P.; Hirsch, Annette L.; Vogel, Martha M.; Brovkin, Victor; van Vuuren, Detlef P.; Schaller, Nathalie; Boysen, Lena; Calvin, Katherine V.; Doelman, Jonathan; Greve, Peter; Havlik, Petr; Humpenöder, Florian; Krisztin, Tamas; Mitchell, Daniel; Popp, Alexander; Riahi, Keywan; Rogelj, Joeri; Schleussner, Carl-Friedrich; Sillmann, Jana; Stehfest, Elke

2018-05-01

This article investigates projected changes in temperature and water cycle extremes at 1.5°C of global warming, and highlights the role of land processes and land-use changes (LUCs) for these projections. We provide new comparisons of changes in climate at 1.5°C versus 2°C based on empirical sampling analyses of transient simulations versus simulations from the `Half a degree Additional warming, Prognosis and Projected Impacts' (HAPPI) multi-model experiment. The two approaches yield similar overall results regarding changes in climate extremes on land, and reveal a substantial difference in the occurrence of regional extremes at 1.5°C versus 2°C. Land processes mediated through soil moisture feedbacks and land-use forcing play a major role for projected changes in extremes at 1.5°C in most mid-latitude regions, including densely populated areas in North America, Europe and Asia. This has important implications for low-emissions scenarios derived from integrated assessment models (IAMs), which include major LUCs in ambitious mitigation pathways (e.g. associated with increased bioenergy use), but are also shown to differ in the simulated LUC patterns. Biogeophysical effects from LUCs are not considered in the development of IAM scenarios, but play an important role for projected regional changes in climate extremes, and are thus of high relevance for sustainable development pathways. This article is part of the theme issue `The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'.

Structural and optical characteristics of in-situ sputtered highly oriented 15R-SiC thin films on different substrates

NASA Astrophysics Data System (ADS)

Mourya, Satyendra; Jaiswal, Jyoti; Malik, Gaurav; Kumar, Brijesh; Chandra, Ramesh

2018-01-01

In this work, we have reported the in-situ fabrication of nanocrystalline rhombohedral silicon carbide (15R-SiC) thin films by RF-magnetron sputtering at 800 °C substrate temperature. The structural and optical properties were investigated for the films grown on four different substrates (ZrO2, MgO, SiC, and Si). The contact angle measurement was performed on all the substrates to investigate the role of interfacial surface energy in nucleation and growth of the films. The XRD measurement revealed the growth of (1 0 10) orientation for all the samples and demonstrated better crystallinity on Si substrate, which was further corroborated by the TEM results. The Raman spectroscopy confirmed the growth of rhombohedral phase with 15R polytype. Surface characteristics of the films have been investigated by energy dispersive x-ray spectroscopy, FTIR, and atomic force microscope (AFM) to account for chemical composition, bonding, and root mean square surface roughness (δrms). The optical dispersion behavior of 15R-SiC thin films was examined by variable angle spectroscopic ellipsometry in the wide spectral range (246-1688 nm), including the surface characteristics in the optical model. The non-linear optical parameters (χ3 and n2) of the samples have been calculated by the Tichy and Ticha relation using a single effective oscillator model of Wemple and Didomenico. Additionally, our optical results provided an alternative way to measure the ratio of carrier concentration to the effective mass (N/m*). These investigated optical parameters allow one to design and fabricate optoelectronic, photonic, and telecommunication devices for deployment in extreme environment.

Dehydration and dehydroxylation of C-S-H phases synthesized on silicon wafers

NASA Astrophysics Data System (ADS)

Giraudo, Nicolas; Bergdolt, Samuel; Laye, Fabrice; Krolla, Peter; Lahann, Joerg; Thissen, Peter

2018-03-01

In this work, the synthesis of specific ultrathin Calcium-Silicate-Hydrate (C-S-H) phases on silicon wafers and their transformation into C-S phases is achieved. Specific mineral phases are identified, and the synthesis is successful controlled. Samples are investigated by means of Fourier Transform Infrared (FTIR) spectroscopy and X-ray Diffraction (XRD) and the results are analyzed based on first-principles calculations. When C-S-H phases are transformed into C-S phases, only a few reflexes are detected on XRD, and the coherent scattering domains decrease with the increment of the temperature and time of exposure. This behavior is explained by the Ca/Si changes, which are identified by changes in the FTIR spectra. A thermodynamic analysis is performed with the help of first-principles calculations to underline the influence of the calcium-to-silicon (Ca/Si) ratio in the process of dehydroxylation. To increase the Ca/Si ratio water is partially substituted by methanol at the synthesis. This is observed in the FTIR spectra and is confirmed by lower temperatures of dehydroxylation. The catalytic nature of calcium towards the dehydroxylation is confirmed. The core of this work lies in the preparation of a model, which perfection makes possible to model reactivity, stability and mechanical properties using first-principles calculations, and is the starting point for the synthesis of many others.

17 CFR 240.15c3-4 - Internal risk management control systems for OTC derivatives dealers.

Code of Federal Regulations, 2013 CFR

2013-04-01

... unenforceable; (6) Procedures are in place to identify and address any deficiencies in the operating systems and... control systems for OTC derivatives dealers. 240.15c3-4 Section 240.15c3-4 Commodity and Securities...-Counter Markets § 240.15c3-4 Internal risk management control systems for OTC derivatives dealers. (a) An...

17 CFR 240.15c3-4 - Internal risk management control systems for OTC derivatives dealers.

Code of Federal Regulations, 2011 CFR

2011-04-01

... unenforceable; (6) Procedures are in place to identify and address any deficiencies in the operating systems and... control systems for OTC derivatives dealers. 240.15c3-4 Section 240.15c3-4 Commodity and Securities...-Counter Markets § 240.15c3-4 Internal risk management control systems for OTC derivatives dealers. (a) An...

17 CFR 240.15c3-4 - Internal risk management control systems for OTC derivatives dealers.

Code of Federal Regulations, 2012 CFR

2012-04-01

... unenforceable; (6) Procedures are in place to identify and address any deficiencies in the operating systems and... control systems for OTC derivatives dealers. 240.15c3-4 Section 240.15c3-4 Commodity and Securities...-Counter Markets § 240.15c3-4 Internal risk management control systems for OTC derivatives dealers. (a) An...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Xiaonan; Lin, Kun; Gao, Qilong

As one class of the most important intermetallic compounds, the binary Laves-phase is well-known for their abundant magnetic properties. Samarium-iron alloy system, SmFe 2, is a prototypical Laves compound that shows strong negative magnetostriction but relatively weak magnetocrystalline anisotropy. SmFe 2 has been identified as a cubic Fdmore » $$ \\overline{3}\\ $$m structure at room temperature, however, the cubic symmetry does not match the spontaneous magnetization along the [111] cubic direction. Here we studied the crystal structure of SmFe 2 by high-resolution synchrotron X-ray powder diffraction and X-ray total scattering methods. SmFe 2 is found to adopt a centrosymmetric trigonal R$$ \\overline{3}\\ $$m structure at room temperature, which transforms to an orthorhombic Imma structure at 200 K. This transition is in agreement with the changes of easy magnetization direction from [111] cubic to [110] cubic direction, and is further evidenced by the inflexion of thermal expansion behavior, the sharp decline of the magnetic susceptibility in the FC-ZFC curve, and the anomaly in the specific heat capacity measurement. The revised structure and phase transformation of SmFe 2 could be useful to understand the magnetostriction and related physical properties of other RM 2-type pseudo-cubic Laves-phase intermetallic compounds.« less

EXOGENOUS CYTOCHROME C RESTORES MYOCARDIAL CYTOCHROME OXIDASE ACTIVITY INTO THE LATE PHASE OF SEPSIS

PubMed Central

Piel, David A.; Deutschman, Clifford S.; Levy, Richard J.

2009-01-01

Mitochondrial dysfunction is thought to play a role in the pathogenesis of a variety of disease states, including sepsis. An acquired defect in oxidative phosphorylation potentially causes sepsis-induced organ dysfunction. Cytochrome oxidase (CcOX), the terminal oxidase of the respiratory chain, is competitively inhibited early in sepsis and progresses, becoming noncompetitive during the late phase. We have previously demonstrated that exogenous cytochrome c can overcome myocardial CcOX competitive inhibition and improve cardiac function during murine sepsis at the 24-h point. Here, we evaluate the effect of exogenous cytochrome c on CcOX activity and survival in mice at the later time points. Exogenous cytochrome c (800 μg) or saline was intravenously injected 24 h after cecal ligation and puncture (CLP) or sham operation. Steady-state mitochondrial cytochrome c levels and heme c content increased significantly 48 h post-CLP and remained elevated at 72 h in cytochrome c-injected mice compared with saline injection. Cecal ligation and puncture inhibited CcOX at 48 h in saline-injected mice. However, cytochrome c injection abrogated this inhibition and restored CcOX kinetic activity to sham values at 48 h. Survival after CLP to 96 h after cytochrome c injection approached 50% compared with only 15% after saline injection. Thus, a single injection of exogenous cytochrome c 24 h post-CLP repletes mitochondrial substrate levels for up to 72 h, restores myocardial COX activity, and significantly improves survival. PMID:18414235

Keeping global warming within 1.5 °C constrains emergence of aridification

NASA Astrophysics Data System (ADS)

Park, Chang-Eui; Jeong, Su-Jong; Joshi, Manoj; Osborn, Timothy J.; Ho, Chang-Hoi; Piao, Shilong; Chen, Deliang; Liu, Junguo; Yang, Hong; Park, Hoonyoung; Kim, Baek-Min; Feng, Song

2018-01-01

Aridity—the ratio of atmospheric water supply (precipitation; P) to demand (potential evapotranspiration; PET)—is projected to decrease (that is, areas will become drier) as a consequence of anthropogenic climate change, exacerbating land degradation and desertification1-6. However, the timing of significant aridification relative to natural variability—defined here as the time of emergence for aridification (ToEA)—is unknown, despite its importance in designing and implementing mitigation policies7-10. Here we estimate ToEA from projections of 27 global climate models (GCMs) under representative concentration pathways (RCPs) RCP4.5 and RCP8.5, and in doing so, identify where emergence occurs before global mean warming reaches 1.5 °C and 2 °C above the pre-industrial level. On the basis of the ensemble median ToEA for each grid cell, aridification emerges over 32% (RCP4.5) and 24% (RCP8.5) of the total land surface before the ensemble median of global mean temperature change reaches 2 °C in each scenario. Moreover, ToEA is avoided in about two-thirds of the above regions if the maximum global warming level is limited to 1.5 °C. Early action for accomplishing the 1.5 °C temperature goal can therefore markedly reduce the likelihood that large regions will face substantial aridification and related impacts.

Solid-phase classical complement activation by C-reactive protein (CRP) is inhibited by fluid-phase CRP-C1q interaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sjoewall, Christopher; Wetteroe, Jonas; Bengtsson, Torbjoern

2007-01-05

C-reactive protein (CRP) interacts with phosphorylcholine (PC), Fc{gamma} receptors, complement factor C1q and cell nuclear constituents, yet its biological roles are insufficiently understood. The aim was to characterize CRP-induced complement activation by ellipsometry. PC conjugated with keyhole limpet hemocyanin (PC-KLH) was immobilized to cross-linked fibrinogen. A low-CRP serum with different amounts of added CRP was exposed to the PC-surfaces. The total serum protein deposition was quantified and deposition of IgG, C1q, C3c, C4, factor H, and CRP detected with polyclonal antibodies. The binding of serum CRP to PC-KLH dose-dependently triggered activation of the classical pathway. Unexpectedly, the activation was efficientlymore » down-regulated at CRP levels >150 mg/L. Using radial immunodiffusion, CRP-C1q interaction was observed in serum samples with high CRP concentrations. We propose that the underlying mechanism depends on fluid-phase interaction between C1q and CRP. This might constitute another level of complement regulation, which has implications for systemic lupus erythematosus where CRP is often low despite flare-ups.« less

Effects of elevated temperature and mobile phase composition on a novel C18 silica column.

PubMed

Lippert, J Andreas; Johnson, Todd M; Lloyd, Jarem B; Smith, Jared P; Johnson, Bryce T; Furlow, Jason; Proctor, Angela; Marin, Stephanie J

2007-05-01

A novel polydentate C18 silica column was evaluated at an elevated temperature under acidic, basic, and neutral mobile phase conditions using ACN and methanol as the mobile phase organic modifier. The temperature range was 40-200 degrees C. The mobile phase compositions were from 0 to 80% organic-aqueous v/v and the mobile phase pH levels were between 2 and 12. The maximum operating temperature of the column was affected by the amount and type of organic modifier used in the mobile phase. Under neutral conditions, the column showed good column thermal stability at temperatures ranging between 120 and 200 degrees C in methanol-water and ACN-water solvent systems. At pH 2 and 3, the column performed well up to about 160 degrees C at two fixed ACN-buffer compositions. Under basic conditions at elevated temperatures, the column material deteriorated more quickly, but still remained stable up to 100 degrees C at pH 9 and 60 degrees C at pH 10. The results of this study indicate that this novel C18 silica-based column represents a significant advancement in RPLC column technology with enhanced thermal and pH stability when compared to traditional bonded phase silica columns.

Bomb-pulse 14C analysis combined with 13C and 15N measurements in blood serum from residents of Malmö, Sweden.

PubMed

Georgiadou, Elisavet; Stenström, Kristina Eriksson; Uvo, Cintia Bertacchi; Nilsson, Peter; Skog, Göran; Mattsson, Sören

2013-05-01

The (14)C content of 60 human blood serum samples from residents of Malmö (Sweden) in 1978, obtained from a biobank, has been measured to estimate the accuracy of (14)C bomb-pulse dating. The difference between the date estimated using the Calibomb software and sampling date varied between -3 ± 0.4 and +0.2 ± 0.5 years. The average age deviation of all samples was -1.5 ± 0.7 years, with the delay between production and consumption of foodstuffs being probably the dominating cause. The potential influence of food habits on the (14)C date has been evaluated using stable isotope δ(13)C and δ(15)N analysis and information about the dietary habits of the investigated individuals. Although the group consisting of lacto-ovo vegetarians and vegans (pooled group) was not completely separated from the omnivores in a stable isotopic trophic level diagram, this analysis proved to add valuable information on probable dietary habits. The age deviation of the sampling date from the respective Calibomb date was found strongly correlated with the δ(13)C values, probably due to influence from marine diet components. For the omnivore individuals, there were indications of seasonal effects on δ(13)C and the age deviation. No significant correlation was found between the age deviation and the δ(15)N values of any dietary group. No influence of sex or year of birth was found on neither the (14)C nor the δ(13)C and δ(15)N values of the serum samples. The data were also divided into two groups (omnivores and pooled group), based on the level of δ(15)N in the samples. The consumption of high δ(15)N-valued fish and birds can be responsible for this clustering.

The projected effect on insects, vertebrates, and plants of limiting global warming to 1.5°C rather than 2°C.

PubMed

Warren, R; Price, J; Graham, E; Forstenhaeusler, N; VanDerWal, J

2018-05-18

In the Paris Agreement on Climate Change, the United Nations is pursuing efforts to limit global warming to 1.5°C, whereas earlier aspirations focused on a 2°C limit. With current pledges, corresponding to ~3.2°C warming, climatically determined geographic range losses of >50% are projected in ~49% of insects, 44% of plants, and 26% of vertebrates. At 2°C, this falls to 18% of insects, 16% of plants, and 8% of vertebrates and at 1.5°C, to 6% of insects, 8% of plants, and 4% of vertebrates. When warming is limited to 1.5°C as compared with 2°C, numbers of species projected to lose >50% of their range are reduced by ~66% in insects and by ~50% in plants and vertebrates. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Phase Decomposition in the Fe-rich Fe-Ni-S System from 900 Degrees C to 300 Degrees C--Application to Meteoritic Metal

NASA Astrophysics Data System (ADS)

Ma, L.; Williams, D. B.; Goldstein, J. I.

1995-09-01

It has been observed that metal particles in ordinary chondrites contain essentially no P and that the tetrataenite rim of the metal particles is much wider than that in other types of meteorites, especially when the taenite rim abuts troilites (FeS) [1]. It is possible that S plays an important role in the formation of the zoned tetrataenite at low cooling temperatures. Most of the studies of the Fe-Ni-S system have concentrated on high temperature and high Ni-high S part of the ternary diagram [2][3]. In this study we have systematically investigated the microstructure and microchemistry of the Fe-rich Fe-Ni-S system in regions where meteoritic metal forms from 900 degrees C down to 300 degrees C. High spatial resolution electron probe microanalysis (EPMA) and analytical electron microscopy (AEM) techniques were employed. The two and three phase boundaries at high temperatures (900 degrees C to 600 degrees C) are consistent with previous studies. However, at 500 degrees C, an Fe-Ni phase with 51.6 +/- 1.4 wt.% Ni was observed to form along some of the g/g and g/FeS boundaries. The size of this Fe-Ni phase is as large as 10 micrometers in width. AEM analysis indicates that this Fe-Ni phase may have even higher Ni content, 56 wt.%. In addition, the phase has a FCC structure and is disordered. Because the composition of this phase is very close to the stoichiometric composition of FeNi, it is very likely that the phase is tetrataenite. High Ni precipitates with similar morphology were also observed in the Fe-Ni-S alloy aged at 400 degrees C. However, the Ni content is 60.9 +/- 4.0 wt.% measured with EPMA, which is much higher than that in the corresponding 500 degree C sample. The fact that all the high Ni precipitates formed at boundaries of g/g or g/FeS indicates the boundaries are favorable energy nucleation sites. Such a high Ni phase with a Ni content over 60 wt.% has not been observed in the Fe-Ni and Fe-Ni (P) systems above 400 degrees C. The tetrataenite

Pathways limiting warming to 1.5°C: a tale of turning around in no time?

NASA Astrophysics Data System (ADS)

Kriegler, Elmar; Luderer, Gunnar; Bauer, Nico; Baumstark, Lavinia; Fujimori, Shinichiro; Popp, Alexander; Rogelj, Joeri; Strefler, Jessica; van Vuuren, Detlef P.

2018-05-01

We explore the feasibility of limiting global warming to 1.5°C without overshoot and without the deployment of carbon dioxide removal (CDR) technologies. For this purpose, we perform a sensitivity analysis of four generic emissions reduction measures to identify a lower bound on future CO2 emissions from fossil fuel combustion and industrial processes. Final energy demand reductions and electrification of energy end uses as well as decarbonization of electricity and non-electric energy supply are all considered. We find the lower bound of cumulative fossil fuel and industry CO2 emissions to be 570 GtCO2 for the period 2016-2100, around 250 GtCO2 lower than the lower end of available 1.5°C mitigation pathways generated with integrated assessment models. Estimates of 1.5°C-consistent CO2 budgets are highly uncertain and range between 100 and 900 GtCO2 from 2016 onwards. Based on our sensitivity analysis, limiting warming to 1.5°C will require CDR or terrestrial net carbon uptake if 1.5°C-consistent budgets are smaller than 650 GtCO2. The earlier CDR is deployed, the more it neutralizes post-2020 emissions rather than producing net negative emissions. Nevertheless, if the 1.5°C budget is smaller than 550 GtCO2, temporary overshoot of the 1.5°C limit becomes unavoidable if CDR cannot be ramped up faster than to 4 GtCO2 in 2040 and 10 GtCO2 in 2050. This article is part of the theme issue `The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'.

Pathways limiting warming to 1.5°C: a tale of turning around in no time?

PubMed

Kriegler, Elmar; Luderer, Gunnar; Bauer, Nico; Baumstark, Lavinia; Fujimori, Shinichiro; Popp, Alexander; Rogelj, Joeri; Strefler, Jessica; van Vuuren, Detlef P

2018-05-13

We explore the feasibility of limiting global warming to 1.5°C without overshoot and without the deployment of carbon dioxide removal (CDR) technologies. For this purpose, we perform a sensitivity analysis of four generic emissions reduction measures to identify a lower bound on future CO 2 emissions from fossil fuel combustion and industrial processes. Final energy demand reductions and electrification of energy end uses as well as decarbonization of electricity and non-electric energy supply are all considered. We find the lower bound of cumulative fossil fuel and industry CO 2 emissions to be 570 GtCO 2 for the period 2016-2100, around 250 GtCO 2 lower than the lower end of available 1.5°C mitigation pathways generated with integrated assessment models. Estimates of 1.5°C-consistent CO 2 budgets are highly uncertain and range between 100 and 900 GtCO 2 from 2016 onwards. Based on our sensitivity analysis, limiting warming to 1.5°C will require CDR or terrestrial net carbon uptake if 1.5°C-consistent budgets are smaller than 650 GtCO 2 The earlier CDR is deployed, the more it neutralizes post-2020 emissions rather than producing net negative emissions. Nevertheless, if the 1.5°C budget is smaller than 550 GtCO 2 , temporary overshoot of the 1.5°C limit becomes unavoidable if CDR cannot be ramped up faster than to 4 GtCO 2 in 2040 and 10 GtCO 2 in 2050.This article is part of the theme issue 'The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'. © 2018 The Author(s).

Sum-over-states density functional perturbation theory: Prediction of reliable 13C, 15N, and 17O nuclear magnetic resonance chemical shifts

NASA Astrophysics Data System (ADS)

Olsson, Lars; Cremer, Dieter

1996-11-01

Sum-over-states density functional perturbation theory (SOS-DFPT) has been used to calculate 13C, 15N, and 17O NMR chemical shifts of 20 molecules, for which accurate experimental gas-phase values are available. Compared to Hartree-Fock (HF), SOS-DFPT leads to improved chemical shift values and approaches the degree of accuracy obtained with second order Møller-Plesset perturbation theory (MP2). This is particularly true in the case of 15N chemical shifts where SOS-DFPT performs even better than MP2. Additional improvements of SOS-DFPT chemical shifts can be obtained by empirically correcting diamagnetic and paramagnetic contributions to compensate for deficiencies which are typical of DFT.

Climate extremes, land–climate feedbacks and land-use forcing at 1.5°C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seneviratne, Sonia I.; Wartenburger, Richard; Guillod, Benoit P.

This article investigates projected changes in temperature and water cycle extremes at 1.5°C global warming, and highlights the role of land processes and land-use changes (LUC) for these projections. We provide new comparisons of changes in climate at 1.5°C vs 2°C based on empirical sampling analyses of transient simulations vs simulations from the 'Half a degree Additional warming, Prognosis and Projected Impacts' (HAPPI) multi-model experiment. The two approaches yield overall similar results regarding changes in climate extremes on land, and reveal a substantial difference in regional extremes occurrence at 1.5°C vs 2°C. Land processes mediated through soil moisture feedbacks andmore » land-use forcing play a major role for projected changes in extremes at 1.5°C in most mid-latitude regions, including densely populated areas in North America, Europe and Asia. This has important implications for low-emissions scenarios derived from Integrated Assessment Models (IAMs), which include major LUC in ambitious mitigation pathways (e.g. associated with increased bioenergy use), but are also shown to differ in the simulated LUC patterns. Biogeophysical effects from LUC are not considered in the development of IAM scenarios, but play an important role for projected regional changes in climate extremes, and are thus of high relevance for sustainable development pathways.« less

1H, 15N and 13C NMR Assignments of Mouse Methionine Sulfoxide Reductase B2

PubMed Central

Breivik, Åshild S.; Aachmann, Finn L.; Sal, Lena S.; Kim, Hwa-Young; Del Conte, Rebecca; Gladyshev, Vadim N.; Dikiy, Alexander

2011-01-01

A recombinant mouse methionine-r-sulfoxide reductase 2 (MsrB2ΔS) isotopically labeled with 15N and 15N/13C was generated. We report here the 1H, 15N and 13C NMR assignments of the reduced form of this protein. PMID:19636904

Climate Impacts in Europe Under +1.5°C Global Warming

NASA Astrophysics Data System (ADS)

Jacob, Daniela; Kotova, Lola; Teichmann, Claas; Sobolowski, Stefan P.; Vautard, Robert; Donnelly, Chantal; Koutroulis, Aristeidis G.; Grillakis, Manolis G.; Tsanis, Ioannis K.; Damm, Andrea; Sakalli, Abdulla; van Vliet, Michelle T. H.

2018-02-01

The Paris Agreement of the United Nations Framework Convention on Climate Change aims not only at avoiding +2°C warming (and even limit the temperature increase further to +1.5°C), but also sets long-term goals to guide mitigation. Therefore, the best available science is required to inform policymakers on the importance of and the adaptation needs in a +1.5°C warmer world. Seven research institutes from Europe and Turkey integrated their competencies to provide a cross-sectoral assessment of the potential impacts at a pan-European scale. The initial findings of this initiative are presented and key messages communicated. The approach is to select periods based on global warming thresholds rather than the more typical approach of selecting time periods (e.g., end of century). The results indicate that the world is likely to pass the +1.5°C threshold in the coming decades. Cross-sectoral dimensions are taken into account to show the impacts of global warming that occur in parallel in more than one sector. Also, impacts differ across sectors and regions. Alongside the negative impacts for certain sectors and regions, some positive impacts are projected. Summer tourism in parts of Western Europe may be favored by climate change; electricity demand decreases outweigh increases over most of Europe and catchment yields in hydropower regions will increase. However, such positive findings should be interpreted carefully as we do not take into account exogenous factors that can and will influence Europe such as migration patterns, food production, and economic and political instability.

Crop productivity changes in 1.5 °C and 2 °C worlds under climate sensitivity uncertainty

NASA Astrophysics Data System (ADS)

Schleussner, Carl-Friedrich; Deryng, Delphine; Müller, Christoph; Elliott, Joshua; Saeed, Fahad; Folberth, Christian; Liu, Wenfeng; Wang, Xuhui; Pugh, Thomas A. M.; Thiery, Wim; Seneviratne, Sonia I.; Rogelj, Joeri

2018-06-01

Following the adoption of the Paris Agreement, there has been an increasing interest in quantifying impacts at discrete levels of global mean temperature (GMT) increase such as 1.5 °C and 2 °C above pre-industrial levels. Consequences of anthropogenic greenhouse gas emissions on agricultural productivity have direct and immediate relevance for human societies. Future crop yields will be affected by anthropogenic climate change as well as direct effects of emissions such as CO2 fertilization. At the same time, the climate sensitivity to future emissions is uncertain. Here we investigate the sensitivity of future crop yield projections with a set of global gridded crop models for four major staple crops at 1.5 °C and 2 °C warming above pre-industrial levels, as well as at different CO2 levels determined by similar probabilities to lead to 1.5 °C and 2 °C, using climate forcing data from the Half a degree Additional warming, Prognosis and Projected Impacts project. For the same CO2 forcing, we find consistent negative effects of half a degree warming on productivity in most world regions. Increasing CO2 concentrations consistent with these warming levels have potentially stronger but highly uncertain effects than 0.5 °C warming increments. Half a degree warming will also lead to more extreme low yields, in particular over tropical regions. Our results indicate that GMT change alone is insufficient to determine future impacts on crop productivity.

GLAG theory for superconducting property variations with A15 composition in Nb3Sn wires.

PubMed

Li, Yingxu; Gao, Yuanwen

2017-04-25

We present a model for the variation of the upper critical field H c2 with Sn content in A15-type Nb-Sn wires, within the Ginzburg-Landau-Abrikosov-Gor'kov (GLAG) theory frame. H c2 at the vicinity of the critical temperature T c is related quantitatively to the electrical resistivity ρ, specific heat capacity coefficient γ and T c . H c2 versus tin content is theoretically formulated within the GLAG theory, and generally reproduces the experiment results. As Sn content gradually approaches the stoichiometry, A15-type Nb-Sn undergoes a transition from the dirty limit to clean limit, split by the phase transformation boundary. The H-T phase boundary and pinning force show different behaviors in the cubic and tetragonal phase. We dipict the dependence of the composition gradient on the superconducting properties variation in the A15 layer, as well as the curved tail at vicinity of H c2 in the Kramer plot of the Nb 3 Sn wire. This helps understanding of the inhomogeneous-composition inducing discrepancy between the results by the state-of-art scaling laws and experiments.

Risks for the global freshwater system at 1.5 °C and 2 °C global warming

NASA Astrophysics Data System (ADS)

Döll, Petra; Trautmann, Tim; Gerten, Dieter; Müller Schmied, Hannes; Ostberg, Sebastian; Saaed, Fahad; Schleussner, Carl-Friedrich

2018-04-01

To support implementation of the Paris Agreement, the new HAPPI ensemble of 20 bias-corrected simulations of four climate models was used to drive two global hydrological models, WaterGAP and LPJmL, for assessing freshwater-related hazards and risks in worlds approximately 1.5 °C and 2 °C warmer than pre-industrial. Quasi-stationary HAPPI simulations are better suited than transient CMIP-like simulations for assessing hazards at the two targeted long-term global warming (GW) levels. We analyzed seven hydrological hazard indicators that characterize freshwater-related hazards for humans, freshwater biota and vegetation. Using a strict definition for significant differences, we identified for all but one indicator that areas with either significantly wetter or drier conditions (calculated as percent changes from 2006–2015) are smaller in the 1.5 °C world. For example, 7 day high flow is projected to increase significantly on 11% and 21% of the global land area at 1.5 °C and 2 °C, respectively. However, differences between hydrological hazards at the two GW levels are significant on less than 12% of the area. GW affects a larger area and more people by increases—rather than by decreases—of mean annual and 1-in-10 dry year streamflow, 7 day high flow, and groundwater recharge. The opposite is true for 7 day low flow, maximum snow storage, and soil moisture in the driest month of the growing period. Mean annual streamflow shows the lowest projected percent changes of all indicators. Among country groups, low income countries and lower middle income countries are most affected by decreased low flows and increased high flows, respectively, while high income countries are least affected by such changes. The incremental impact between 1.5 °C and 2 °C on high flows would be felt most by low income and lower middle income countries, the effect on soil moisture and low flows most by high income countries.

Synthesis and Characterization of Quenched and Crystalline Phases: Q-Carbon, Q-BN, Diamond and Phase-Pure c-BN

NASA Astrophysics Data System (ADS)

Bhaumik, Anagh; Narayan, Jagdish

2018-04-01

We report the synthesis and characterization of quenched (Q-carbon and Q-BN) and crystalline (diamond and c-BN) phases using a non-equilibrium technique. These phases are formed as a result of the melting and subsequent quenching of amorphous carbon and nanocrystalline h-BN in a super undercooled state by using high-power nanosecond laser pulses. Pulsed laser annealing also leads to the formation of nanoneedles, microneedles and single-crystal thin films of diamond and c-BN. This formation is dependent on the nucleation and growth times, which are controlled by laser energy density and thermal conductivities of substrate and as-deposited thin film. The diamond nuclei present in the Q-carbon structure ( 80% sp 3) can also be grown to larger sizes using the equilibrium hot filament chemical vapor deposition process. The texture of diamond and c-BN crystals is <111> under epitaxial growth and <110> under rapid unseeded crystallization. Our nanosecond laser processing opens up a roadmap to the fabrication of novel phases on heat-sensitive substrates.

Projected changes of thermal growing season over Northern Eurasia in a 1.5 °C and 2 °C warming world

NASA Astrophysics Data System (ADS)

Zhou, Baiquan; Zhai, Panmao; Chen, Yang; Yu, Rong

2018-03-01

Projected changes of the thermal growing season (TGS) over Northern Eurasia at 1.5 °C and 2 °C global warming levels are investigated using 22 CMIP5 models under both RCP4.5 and RCP8.5 scenarios. The multi-model mean projections indicate Northern Eurasia will experience extended and intensified TGSs in a warmer world. The prolongation of TGSs under 1.5 °C and 2 °C warming is attributed to both earlier onset and later termination, with the latter factor playing a dominating role. Interestingly, earlier onset is of greater importance under RCP4.5 than under RCP8.5 in prolonging TGS as the world warms by an additional 0.5 °C. Under both RCPs, growing degree day sum (GDD) above 5 °C is anticipated to increase by 0 °C-450 °C days and 0 °C-650 °C days over Northern Eurasia at 1.5 °C and 2 °C warming, respectively. However, effective GDD (EGDD) which accumulates optimum temperature for the growth of wheat, exhibits a decline in the south of Central Asia under warmer climates. Therefore, for wheat production over Northern Eurasia, adverse effects incurred by scorching temperatures and resultant inadequacy in water availability may counteract benefits from lengthening and warming TGS. In response to a future 1.5 °C and 2 °C warmer world, proper management and scientifically-tailored adaptation are imperative to optimize local-regional agricultural production.

Logarithmic phase Escherichia coli K1 efficiently avoids serum killing by promoting C4bp-mediated C3b and C4b degradation

PubMed Central

Wooster, David G; Maruvada, Ravi; Blom, Anna M; Prasadarao, Nemani V

2006-01-01

Meningitis caused by Escherichia coli K1 is a serious illness in neonates with neurological sequelae in up to 50% of survivors. A high degree of bacteremia is required for E. coli K1 to cross the blood–brain barrier, which suggests that the bacterium must evade the host defence mechanisms and survive in the bloodstream. We previously showed that outer membrane protein A (OmpA) of E. coli binds C4b-binding protein (C4bp), an inhibitor of complement activation via the classical pathway. Nevertheless, the exact mechanism by which E. coli K1 survives in serum remains elusive. Here, we demonstrate that log phase (LP) OmpA+E. coli K1 avoids serum bactericidal activity more effectively than postexponential phase bacteria. OmpA–E. coli cannot survive in serum grown to either phase. The increased serum resistance of LP OmpA+E. coli is the result of increased binding of C4bp, with a concomitant decrease in the deposition of C3b and the downstream complement proteins responsible for the formation of the membrane attack complex. C4bp bound to E. coli K1 acts as a cofactor to factor I in the cleavage of both C3b and C4b, which shuts down the ensuing complement cascade. Accordingly, a peptide corresponding to the complement control protein domain 3 of C4bp sequence, was able to compete with C4bp binding to OmpA and cause increased deposition of C3b. Thus, binding of C4bp appears to be responsible for survival of E. coli K1 in human serum. PMID:16556262

Proliferating cell nuclear antigen (PCNA)-associated KIAA0101/PAF15 protein is a cell cycle-regulated anaphase-promoting complex/cyclosome substrate.

PubMed

Emanuele, Michael J; Ciccia, Alberto; Elia, Andrew E H; Elledge, Stephen J

2011-06-14

The anaphase-promoting complex/cyclosome (APC/C) is a cell cycle-regulated E3 ubiquitin ligase that controls the degradation of substrate proteins at mitotic exit and throughout the G1 phase. We have identified an APC/C substrate and cell cycle-regulated protein, KIAA0101/PAF15. PAF15 protein levels peak in the G2/M phase of the cell cycle and drop rapidly at mitotic exit in an APC/C- and KEN-box-dependent fashion. PAF15 associates with proliferating cell nuclear antigen (PCNA), and depletion of PAF15 decreases the number of cells in S phase, suggesting a role for it in cell cycle regulation. Following irradiation, PAF15 colocalized with γH2AX foci at sites of DNA damage through its interaction with PCNA. Finally, PAF15 depletion led to an increase in homologous recombination-mediated DNA repair, and overexpression caused sensitivity to UV-induced DNA damage. We conclude that PAF15 is an APC/C-regulated protein involved in both cell cycle progression and the DNA damage response.

Scenarios towards limiting global mean temperature increase below 1.5 °C

NASA Astrophysics Data System (ADS)

Rogelj, Joeri; Popp, Alexander; Calvin, Katherine V.; Luderer, Gunnar; Emmerling, Johannes; Gernaat, David; Fujimori, Shinichiro; Strefler, Jessica; Hasegawa, Tomoko; Marangoni, Giacomo; Krey, Volker; Kriegler, Elmar; Riahi, Keywan; van Vuuren, Detlef P.; Doelman, Jonathan; Drouet, Laurent; Edmonds, Jae; Fricko, Oliver; Harmsen, Mathijs; Havlík, Petr; Humpenöder, Florian; Stehfest, Elke; Tavoni, Massimo

2018-04-01

The 2015 Paris Agreement calls for countries to pursue efforts to limit global-mean temperature rise to 1.5 °C. The transition pathways that can meet such a target have not, however, been extensively explored. Here we describe scenarios that limit end-of-century radiative forcing to 1.9 W m-2, and consequently restrict median warming in the year 2100 to below 1.5 °C. We use six integrated assessment models and a simple climate model, under different socio-economic, technological and resource assumptions from five Shared Socio-economic Pathways (SSPs). Some, but not all, SSPs are amenable to pathways to 1.5 °C. Successful 1.9 W m-2 scenarios are characterized by a rapid shift away from traditional fossil-fuel use towards large-scale low-carbon energy supplies, reduced energy use, and carbon-dioxide removal. However, 1.9 W m-2 scenarios could not be achieved in several models under SSPs with strong inequalities, high baseline fossil-fuel use, or scattered short-term climate policy. Further research can help policy-makers to understand the real-world implications of these scenarios.

N-Mesityl-C-acylketenimines: 1,5-Sigmatropic Shifts and Electrocyclization to Quinolines.

PubMed

Rao, V. V. Ramana; Fulloon, Belinda E.; Bernhardt, Paul V.; Koch, Rainer; Wentrup, Curt

1998-08-21

Flash vacuum thermolysis (FVT) of triazoles 6a-c generates alpha-oxoketenimines 10, the ester 10a being isolable. FVT of pyrroledione 8 generates the isomeric imidoylketene 9a. Ketenes 9 and ketenimines 10 undergo thermal interconversion by 1,3-shifts of methoxy and dimethylamino groups under mild FVT conditions (ca. 350-400 degrees C). Both 9 and 10 are directly observable by IR spectroscopy at either 77 K or on Ar matrix isolation at 12 K. On FVT at temperatures above ca. 400 degrees C, the ketenimines 10 undergo a 1,5-H shift to o-quinoid imines 12/13, followed by electrocyclization to dihydroquinolines 14 (unobserved) and 15 (observed by NMR). The latter are easily oxidized to alkylquinoline-3-carboxylates or quinoline-3-carboxamides 16 by atmospheric oxygen. Ab initio calculations on model compounds 18-23 predict an energy barrier of ca. 38 kcal mol(-)(1) (161 kJ mol(-)(1)) for the 1,5-H shift in N-(o-methylphenyl)ketenimines via the transition state TS19 followed by an electrocyclization barrier to dihydroquinoline 23a via TS22a of ca. 16 kcal mol(-)(1).

Permafrost thaw strongly reduces allowable CO2 emissions for 1.5°C and 2°C

NASA Astrophysics Data System (ADS)

Kechiar, M.; Gasser, T.; Kleinen, T.; Ciais, P.; Huang, Y.; Burke, E.; Obersteiner, M.

2017-12-01

We quantify how the inclusion of carbon emission from permafrost thaw impacts the budgets of allowable anthropogenic CO2 emissions. We use the compact Earth system model OSCAR v2.2 which we expand with a permafrost module calibrated to emulate the behavior of the complex models JSBACH, ORCHIDEE and JULES. When using the "exceedance" method and with permafrost thaw turned off, we find budgets very close to the CMIP5 models' estimates reported by IPCC. With permafrost thaw turned on, the total budgets are reduced by 3-4%. This corresponds to a 33-45% reduction of the remaining budget for 1.5°C, and a 9-13% reduction for 2°C. When using the "avoidance" method, however, permafrost thaw reduces the total budget by 3-7%, which corresponds to reductions by 33-56% and 56-79% of the remaining budget for 1.5°C and 2°C, respectively. The avoidance method relies on many scenarios that actually peak below the target whereas the exceedance method overlooks the carbon emitted by thawed permafrost after the temperature target is reached, which explains the difference. If we use only the subset of scenarios in which there is no net negative emissions, the permafrost-induced reduction in total budgets rises to 6-15%. Permafrost thaw therefore makes the emission budgets strongly path-dependent. We also estimate budgets of needed carbon capture in scenarios overshooting the temperature targets. Permafrost thaw strongly increases these capture budgets: in the case of a 1.5°C target overshot by 0.5°C, which is in line with the Paris agreement, about 30% more carbon must be captured. Our conclusions are threefold. First, inclusion of permafrost thaw systematically reduces the emission budgets, and very strongly so if the temperature target is overshot. Second, the exceedance method, that is the only one that complex models can follow, only partially accounts for the effect of slow non-linear processes such as permafrost thaw, leading to overestimated budgets. Third, the newfound

Differential climate impacts for policy-relevant limits to global warming: the case of 1.5 °C and 2 °C

NASA Astrophysics Data System (ADS)

Schleussner, C.-F.; Lissner, T. K.; Fischer, E. M.; Wohland, J.; Perrette, M.; Golly, A.; Rogelj, J.; Childers, K.; Schewe, J.; Frieler, K.; Mengel, M.; Hare, W.; Schaeffer, M.

2015-11-01

Robust appraisals of climate impacts at different levels of global-mean temperature increase are vital to guide assessments of dangerous anthropogenic interference with the climate system. Currently, two such levels are discussed in the context of the international climate negotiations as long-term global temperature goals: a below 2 °C and a 1.5 °C limit in global-mean temperature rise above pre-industrial levels. Despite the prominence of these two temperature limits, a comprehensive assessment of the differences in climate impacts at these levels is still missing. Here we provide an assessment of key impacts of climate change at warming levels of 1.5 °C and 2 °C, including extreme weather events, water availability, agricultural yields, sea-level rise and risk of coral reef loss. Our results reveal substantial differences in impacts between 1.5 °C and 2 °C. For heat-related extremes, the additional 0.5 °C increase in global-mean temperature marks the difference between events at the upper limit of present-day natural variability and a new climate regime, particularly in tropical regions. Similarly, this warming difference is likely to be decisive for the future of tropical coral reefs. In a scenario with an end-of-century warming of 2 °C, virtually all tropical coral reefs are projected to be at risk of severe degradation due to temperature induced bleaching from 2050 onwards. This fraction is reduced to about 90 % in 2050 and projected to decline to 70 % by 2100 for a 1.5 °C scenario. Analyses of precipitation-related impacts reveal distinct regional differences and several hot-spots of change emerge. Regional reduction in median water availability for the Mediterranean is found to nearly double from 9 to 17 % between 1.5 °C and 2 °C, and the projected lengthening of regional dry spells increases from 7 % longer to 11 %. Projections for agricultural yields differ between crop types as well as world regions. While some (in particular high

Climate extremes, land–climate feedbacks and land-use forcing at 1.5°C

DOE PAGES

Seneviratne, Sonia I.; Wartenburger, Richard; Guillod, Benoit P.; ...

2018-04-02

Here, this article investigates projected changes in temperature and water cycle extremes at 1.5°C of global warming, and highlights the role of land processes and land-use changes (LUCs) for these projections. We provide new comparisons of changes in climate at 1.5°C versus 2°C based on empirical sampling analyses of transient simulations versus simulations from the ‘Half a degree Additional warming, Prognosis and Projected Impacts’ (HAPPI) multi-model experiment. The two approaches yield similar overall results regarding changes in climate extremes on land, and reveal a substantial difference in the occurrence of regional extremes at 1.5°C versus 2°C. Land processes mediated throughmore » soil moisture feedbacks and land-use forcing play a major role for projected changes in extremes at 1.5°C in most mid-latitude regions, including densely populated areas in North America, Europe and Asia. This has important implications for low-emissions scenarios derived from integrated assessment models (IAMs), which include major LUCs in ambitious mitigation pathways (e.g. associated with increased bioenergy use), but are also shown to differ in the simulated LUC patterns. Biogeophysical effects from LUCs are not considered in the development of IAM scenarios, but play an important role for projected regional changes in climate extremes, and are thus of high relevance for sustainable development pathways.« less

Climate extremes, land–climate feedbacks and land-use forcing at 1.5°C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seneviratne, Sonia I.; Wartenburger, Richard; Guillod, Benoit P.

Here, this article investigates projected changes in temperature and water cycle extremes at 1.5°C of global warming, and highlights the role of land processes and land-use changes (LUCs) for these projections. We provide new comparisons of changes in climate at 1.5°C versus 2°C based on empirical sampling analyses of transient simulations versus simulations from the ‘Half a degree Additional warming, Prognosis and Projected Impacts’ (HAPPI) multi-model experiment. The two approaches yield similar overall results regarding changes in climate extremes on land, and reveal a substantial difference in the occurrence of regional extremes at 1.5°C versus 2°C. Land processes mediated throughmore » soil moisture feedbacks and land-use forcing play a major role for projected changes in extremes at 1.5°C in most mid-latitude regions, including densely populated areas in North America, Europe and Asia. This has important implications for low-emissions scenarios derived from integrated assessment models (IAMs), which include major LUCs in ambitious mitigation pathways (e.g. associated with increased bioenergy use), but are also shown to differ in the simulated LUC patterns. Biogeophysical effects from LUCs are not considered in the development of IAM scenarios, but play an important role for projected regional changes in climate extremes, and are thus of high relevance for sustainable development pathways.« less

Extreme Temperatures over India in the 1.5°C and 2°C warmer worlds

NASA Astrophysics Data System (ADS)

Thanigachalam, A.; Achutarao, K. M.

2017-12-01

n the summer of 2015 a heat wave claimed more than 2500 lives of southeastern India. Wehner et al., (2016) showed that the risk of this heat wave has increased due to anthropogenic forcings. Under the RCP 8.5 scenario, surface temperature over India shows a rate of increase of about 0.2°C/decade during the 21st Century (Basha et al., 2017). The extreme temperatures that have occurred in the recent past and further increases projected for the future have implications for human health and productivity. In light of the Paris accords, future stabilization of global mean temperature at the 1.5°C above pre-industrial aspirational target and the "not to be exceeded" 2°C target (still higher than current temperatures), the possibility of increases in extreme temperatures under these scenarios is very real. In this study we seek to understand the nature of extreme temperatures over India in the 1.5°C and 2°C worlds in comparison to the current climate. We make use of model output contributed under the Half a degree Additional warming, Prognosis and Projected Impacts project (HAPPI; Mitchell et al., 2017). The HAPPI database contains output from many atmospheric GCMs with multiple simulations ( 100 each) of historical (2005-2015), 1.5°C warmer decade, and 2°C warmer decade. The large number of ensembles provides an opportunity to study the extremes in temperature that occur over India and how they may change. In order to provide insights into the future comparable against current operational practices, we make use of definitions of "hot days", "heat waves", and "severe heat waves" used by the India Meteorological Department (IMD). We compare modelled data (and bias corrected model output where available) against observed daily temperatures from the IMD gridded (1°x1°) dataset available for 1951-2015 as also circulation features that lead to such events by comparing against reanalysis products. We also investigate the timing of such events in the future scenarios

Effect of stresses on the structural changes in high-chromium steel upon creep

NASA Astrophysics Data System (ADS)

Fedoseeva, A. E.; Dudova, N. R.; Kaibyshev, R. O.

2017-06-01

The effect of stresses on the microstructure and dispersed particles in a heating-performance Fe‒0.12C-0.06Si-0.04Ni-0.2Mn-9.5Cr-3.2Co-0.45Mo-3.1W-0.2V-0.06Nb-0.005B-0.05N (wt %) steel has been studied under long-term strength tests at T = 650°C under initial applied stresses ranging from 220 to 100 MPa with a step of 20 MPa. Under an applied stress of 160 MPa, which corresponds to a time to fracture of 1703 h, a transfer from short- to long-term creep takes place. It has been shown that alloying with 3% Co and an increase in W content to 3% significantly increase the short-term creep resistance and slightly increase the long-term strength upon tests by more than 104 h. The transfer from short- to the long-term creep is accompanied by substantial changes in the microstructure of the steel. Under long-term creep, the solid solution became depleted of tungsten and of molybdenum down to the thermodynamically equilibrium content of these elements in the solid solution, which leads to the precipitation of a large amount of fine particles of the Laves phase at the boundaries of laths and prior austenitic grains. At a time to fracture of more than 4 × 103 h, the coalescence of the M23C6 carbides and Laves-phase particles occurs, which causes the transformation of the structure of fine tempered martensite lath structure into a subgrained structure.

The knockout reaction of {sup 15}C on a {sup 9}Be target at intermediate energies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sadeghi, H., E-mail: H-Sadeghi@araku.ac.ir; Fereidonnejad, R.; Ghambari, M.

2016-05-15

In this work, neutron knockout reactions of {sup 15}C on a {sup 9}Be target at energy 103 and 250 MeV/nucleon are studied. Using the Eikonal approximation of the Glauber model, total neutron removal cross sections, the stripping and diffractive cross sections as well as {sup 14}C longitudinal momentum distributions are determined in both {sup 15}C ground state and exited states of the wave function. We compared the results of our calculations with the available experimental data obtained recently. The calculated cross sections of {sup 15}C and {sup 14}C reactions, as well as the momentum distribution are in relatively good agreementmore » with available data.« less

Superconducting phase transitions in mK temperature range in splat-cooled U0.85Pt0.15 alloys

NASA Astrophysics Data System (ADS)

Kim-Ngan, N.-T. H.; Tarnawski, Z.; Chrobak, M.; Sowa, S.; Duda, A.; Paukov, M.; Buturlim, V.; Havela, L.