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Yang, Ping

Publications and source records attributed to Yang, Ping.

At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Atomic-Scale Control of Magnetism at the Titanite-Manganite Interfaces

Complex oxide thin-film heterostructures often exhibit magnetic properties different from those known for bulk constituents. This is due to the altered local structural and electronic environment at the interfaces, which affects the exchange coupling and magnetic ordering. The emergent magnetism at oxide interfaces can be controlled by ferroelectric polarization and has a strong effect on spin-dependent transport properties of oxide heterostructures, including magnetic and ferroelectric tunnel junctions. In this work, using prototype La 2/3 Sr 1/3 MnO 3 /BaTiO 3 heterostructures, we show that ferroelectric polarization of BaTiO 3 controls the orbital hybridization and magnetism at heterointerfaces. We observe changes in the enhanced orbital occupancy and significant charge redistribution across the heterointerfaces, affecting the spin and orbital magnetic moments of the interfacial Mn and Ti atoms. Notably, we find that the exchange coupling between Mn and Ti atoms across the interface is tuned by ferroelectric polarization from ferromagnetic to antiferromagnetic. Our findings provide a viable route to electrically control complex magnetic configurations at artificial multiferroic interfaces, taking a step toward low-power spintronics.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Homoleptic Imidophosphorane Stabilization of Tetravalent Cerium

We present that the homoleptic complexes of cerium with the tris(piperidinyl)imidophosphorane ligand, [NP(pip) 3 ] - , present the most negative Ce 3+ /4+ redox couple known (<-2.64 V vs Fc/Fc + ). This dramatic stabilization of the cerium tetravalent oxidation state [>4.0 V shift from the Ce 3+/4+ couple in 1 M HClO 4 (aq)] is established through reactivity studies. Spectroscopic studies (UV–vis, electron paramagnetic resonance, and Ce L 3 -edge X-ray absorption spectroscopy), in conjunction with density functional theory studies, reveal the dominant covalent metal–ligand interactions underlying the observed redox chemistry and the dependence of the redox potential on the binding of potassium in the inner coordination sphere.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Soft-donor dipicolinamide derivatives for selective actinide( iii )/lanthanide( iii ) separation: the role of S- vs. O-donor sites

Selectivity for An(III) vs. Ln(III) binding and extraction with dipicolinamide analogs containing the C=O vs. C=S groups was investigated in solution and the gas-phase, and by DFT calculations. The results reflect higher selectivity for complex formation and extraction for Am(III) vs. Eu(III) for the softer dithioamide vs. the diamide ligand, while in CH 3 CN the diamide binds more strongly than the thioamide to several Ln(III), forming 1:1 complexes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

AnO2-Cl Coordination Chemistry at High P/T

This presentation covers the following topics: Materials synthesis & characterization; In-situ structural determination using synchrotron and Raman techniques; Thermodynamic measurements (solubility measurements + calorimetry)

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Linked Picolinamide Nickel Complexes as Redox Carriers for Nonaqueous Flow Batteries

Here, the use of nickel complexes utilizing non–innocent ligands based on picolinamide to function as redox carriers in flow batteries was explored. The picolinamide moiety was linked together with –CH 2 CH 2 – (bpen), –CH 2 CH 2 CH 2 – (bppn), and –C 6 H 4 – (bpb) moieties, resulting in two, three, and four quasi–reversible waves, respectively, for the nickel complexes and >3 V difference between the outermost positive and negative waves. The redox events were theoretically modelled for each complex, showing excellent agreement (<0.3 V difference) between the experimental and modelled potentials. Bulk cycling of the most soluble complex, Ni(bppn), indicated only one of the three waves was reversible. Therefore, Ni(bppn) has the ability to act as a negative charge redox carrier in flow cells.

25 ENERGY STORAGE↗
DOE OSTI2019

Anti-Diabetic and Anti-Nephritic Activities of Grifola frondosa Mycelium Polysaccharides in Diet-Streptozotocin-Induced Diabetic Rats Via Modulation on Oxidative Stress

Grifola frondosa is an edible fungus with a variety of potential pharmacological activities. This study investigates the hypoglycemic, anti-diabetic nephritic, and antioxidant properties of G. frondosa polysaccharides in diet-streptozotocin-induced diabetic rats. After a 4-week treatment with 100 mg/kg of metformin and 200 mg/kg of one of four different G. frondosa polysaccharide mixtures (especially GFPS3 and GFPS4), diabetic rats had enhanced body weight and suppressed plasma glucose, indicating the hypoglycemic activities of the G. frondosa polysaccharides. G. frondosa polysaccharides regulated the level of serum creatinine, blood urea nitrogen, N-acetyl-β-D-glucosaminidase, and albuminuria; inhibited the serum levels of interleukin (IL)-2, IL-6, and TNF-α; and enhanced the serum levels of matrix metalloproteinase 9 and interferon-α, confirming their anti-diabetic nephritic activities. G. frondosa polysaccharides ameliorated the pathological alterations in the kidneys of diabetic rats. Moreover, G. frondosa polysaccharides modulated the serum levels of oxidant factors such as superoxide dismutase, glutathione peroxidase, catalase, malondialdehyde, and reactive oxygen species, revealing their antioxidant properties. Furthermore, the administration of G. frondosa polysaccharides inhibited nuclear factor kappa B activities in the serum and kidneys. All of the data revealed that the activation of nuclear factor kappa B plays a central role in G. frondosa polysaccharide-mediated anti-diabetic and anti-nephritic activities.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Energy-Degeneracy-Driven Covalency in Actinide Bonding

Evaluating the nature of chemical bonding for actinide elements represents one of the most important and long-standing problems in actinide science. In this work, we directly address this challenge and contribute a Cl K-edge X-ray absorption spectroscopy and relativistic density functional theory study that quantitatively evaluates An–Cl covalency in AnCl 6 2– (An IV = Th, U, Np, Pu). Lastly, the results showed significant mixing between Cl 3p- and An IV 5f- and 6d-orbitals (t 1u */t 2u * and t 2g */e g *), with the 6d-orbitals showing more pronounced covalent bonding than the 5f-orbitals. Moving from Th to U, Np, and Pu markedly changed the amount of M–Cl orbital mixing, such that An IV 6d- and Cl 3p-mixing decreased and metal 5f- and Cl 3p-orbital mixing increased across this series.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Transition from the twinning induced plasticity to the γ-ε transformation induced plasticity in a high manganese steel

Neutron-diffraction investigation on the deformation of a Fe-18Mn-3Si-0.6C-0.4Al steel reveals that the twinning is mainly dominant at a stress below 900 MPa, above which the twinning behavior is largely outweighed by phase transformation from the face-centered-cubic (FCC) γ-austenite to the hexagonal-close-packed (HCP) ε-martensite. In the deformed grains, the distribution of ε-martensite is parallel with the twin boundary. Both the well-known {111} γ //{0001} ε relationship and an additional {111} γ //{11–21} ε orientation relation were identified. After the phase transformation, both phases deformed further with the lattice rotating around an axis perpendicular to the tensile direction. Transition from the twinning dominant behavior to the phase transformation induced plasticity effect is explained by the grain orientation dependence of the effective stacking fault energy (ESFE). An asymmetric and inverse relationship between the width of stacking faults (SF) and the ESFE is obtained from the density functional theory (DFT). The tensile stress always increases proportionally with the SF width in the twinning favorable grains and thus a decreasing ESFE. The replacement of twinning activities by phase transformation could be due to both the nucleation site of ε-martensite at the SF of the twin boundary and the decrease of the ESFE in grains which originally favors the twinning.

Materials Science↗
DOE OSTI2018

Plutonium coordination and redox chemistry with the CyMe 4 -BTPhen polydentate N-donor extractant ligand

Here complexation of Pu(IV) with the actinide extractant CyMe 4 -BTPhen (2,9-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzotriazin-3-yl)-1,10-phenanthroline) was followed by vis-NIR spectroscopy in acetonitrile solution. The solid-state structure of the crystallized product suggests that Pu(IV) is reduced to Pu(III) upon complexation. Analysis by DFT modeling is consistent with metal-based rather than ligand-based reduction.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2018

Control of magnetic anisotropy by orbital hybridization with charge transfer in (La 0.67 Sr 0.33 MnO 3 ) n /(SrTiO 3 ) n superlattice

Here, the chemical asymmetry at the hetero-structure interface offers an effective opportunity to design desirable electronic structures by controlling charge transfer and orbital hybridization across the interface. However, controlling the hetero-interface remains a daunting task. Here, we report the modulation of interfacial coupling of (La 0.67 Sr 0.33 MnO 3 ) n /(SrTiO 3 ) n superlattices by manipulating the periodic thickness with n unit cells of SrTiO 3 and n unit cells of La 0.67 Sr 0.33 MnO 3 with a fixed thickness of ~120 unit cells. The easy axis of magnetic anisotropy rotates ~45° towards the out-of-plane direction from n = 10 to n = 2 at reduced temperature T Re = T/T S = 0.87, where T S is the temperature at the onset of magnetization.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

A series of dithiocarbamates for americium, curium, and californium

Characterizing how actinide properties change across the f-element series is critical for improving predictive capabilities and solving many nuclear problems facing our society. Unfortunately, it is difficult to make direct comparisons across the 5f-element series because so little is known about trans-plutonium elements. Results described in this paper help to address this issue through isolation of An(S 2 CNEt 2 ) 3 (N 2 C 12 H 8 ) (Am, Cm, and Cf). These findings included the first single crystal X-ray diffraction measurements of Cm–S (mean of 2.86 ± 0.04 Å) and Cf–S (mean of 2.84 ± 0.04 Å) bond distances. Furthermore, they highlight the potential of An(S 2 CNEt 2 ) 3 (N 2 C 12 H 8 ) for providing a test bed for comparative analyses of actinide versus lanthanide bonding interactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Revisiting complexation thermodynamics of transplutonium elements up to einsteinium

Literature casts einsteinium as a departure from earlier transplutonium actinides, with a decrease in stability constants with aminopolycarboxylate ligands. This work studies transplutonium chemistry – including Am, Bk, Cf, and Es – with aminopolycarboxylate ligands. Es complexation follows similar thermodynamic and structural trends established by the earlier actinides, consistent with first-principle calculations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2018

Net Radiative Effects of Dust in the Tropical North Atlantic Based on Integrated Satellite Observations and in Situ Measurements

In this study, we integrate recent in situ measurements with satellite retrievals of dust physical and radiative properties to quantify dust direct radiative effects on shortwave (SW) and longwave (LW) radiation (denoted as DRESW and DRELW, respectively) in the tropical North Atlantic during the summer months from 2007 to 2010. Through linear regression of the CERES-measured top-of atmosphere (TOA) flux versus satellite aerosol optical depth (AOD) retrievals, we estimate the instantaneous DRESW efficiency at the TOA to be -49+/-7.1 W/sq.m AOD(exp -1) and -36+/-4:8W/sq.m AOD(exp -1) based on AOD from MODIS and CALIOP, respectively. We then perform various sensitivity studies based on recent measurements of dust particle size distribution (PSD), refractive index, and particle shape distribution to determine how the dust microphysical and optical properties affect DRE estimates and its agreement with the above-mentioned satellite-derived DREs. Our analysis shows that a good agreement with the observation-based estimates of instantaneous DRESW and DRELW can be achieved through a combination of recently observed PSD with substantial presence of coarse particles, a less absorptive SW refractive index, and spheroid shapes. Based on this optimal combination of dust physical properties we further estimate the diurnal mean dust DRE(sub SW) in the region of -10W/sq.m at TOA and -26W/sq.m at the surface, respectively, of which ~30% is canceled out by the positive DRE(sub LW). This yields a net DRE of about -6:9 and -18.3 W/sq.m at TOA and the surface, respectively. Our study suggests that the LW flux contains useful information on dust particle size, which could be used together with SW observations to achieve a more holistic understanding of the dust radiative effect.

Song, Qianqian↗
DOE OSTI2018

Facile synthesis of various α-Fe2O3 micro/nanostructures: Highlighting on the enhanced catalysis activities by formation of bowl-like α-Fe2O3/Au composites

Highlights: • Various α-Fe{sub 2}O{sub 3} micro/nanostructures are fabricated by a hydrothermal method. • The morphologies are tunable by changing the content of NaHCO{sub 3} and reaction time. • Bowl-like α-Fe{sub 2}O{sub 3} has the highest Fenton catalytic efficiency in dark condition. • Fast photo-Fenton reaction of α-Fe{sub 2}O{sub 3}/Au can be tuned by multiphase structures. • Bowl-like α-Fe{sub 2}O{sub 3}/Au is an excellent photo-Fenton catalyst for water treatment. - Abstract: Various α-Fe{sub 2}O{sub 3} micro/nanostructures referring to spherical-like, bowl-like, cubic, and discoid shapes have been fabricated by a facile hydrothermal method using sodium bicarbonate as surfactant and alkaline reagents, displaying superior Fenton catalytic performances for degradation of Rhodamine 6G. Because of abundant exposed crystal surfaces such as (110) and (104) on the surfaces of bowl-like α-Fe{sub 2}O{sub 3}, the rapid degradation rate of 90.0% in 5 min is observed under the dark condition as the adding amount of H{sub 2}O{sub 2} limiting to 300 μL. Significantly, the enhanced catalytic performances of bowl-like α-Fe{sub 2}O{sub 3}/Au catalysts under natural light condition have been investigated and carried out by in situ reduction of well-distributed Au nanoparticles with average sizes of 3–6 nm. Due to the appropriate phase structures and heterogenous interface properties, the highest photo-Fenton catalytic activity with the degradation rate of 90.0% in 2 min can be obtained for α-Fe{sub 2}O{sub 3}/Au{sub 0.01} composites.

77 NANOSCIENCE AND NANOTECHNOLOGY↗