Engineering topics
Chen, J
Publications and source records attributed to Chen, J.
Correlating ethylene glycol reforming activity with in-situ EXAFS detection of Ni segregation in supported NiPt bimetallic catalysts
The structural changes in supported NiPt/C and NiPt/γ-Al2O3 catalysts were investigated using in-situ extended X-ray absorption fine structure (EXAFS) under aqueous phase reforming (APR) of ethylene glycol conditions. Reverse Monte Carlo is introduced to analyze the EXAFS data. Parallel reactor studies of APR of ethylene glycol showed that NiPt catalysts were initially more active than monometallic Pt catalysts. The enhanced activity was correlated to changes in the catalyst structure. Under APR conditions, Ni segregated to the surface of the catalysts, resembling Ni-terminated bimetallic surfaces that were predicted to be more active than Pt from theoretical and experimental studies on model surfaces.
High-Pressure Raman and X-ray Diffraction Study of [beta]- and [gamma]-Polymorphs of Aluminum Hydride
Three polymorphs of alane, AlH{sub 3}, ({alpha}, {beta}, and {gamma}) were synthesized and studied at high-pressure in diamond anvil cell by Raman spectroscopy and synchrotron X-ray diffraction. According to synchrotron X-ray diffraction study, {beta}-AlH{sub 3} is stable up to 6 GPa, followed by transformation into {alpha} phase at higher pressures. X-ray-induced decomposition {gamma}-AlH{sub 3} into constituent elements was found at 15 GPa. Raman scattering study at high pressure for both {beta}- and {gamma}-AlH{sub 3} reveals transition into the {alpha} phase with high concentration of structural defects. DFT calculations (VASP code) show that instability of cubic {beta}-alane crystal structure at high pressure is caused by the strong deformation of the [AlH{sub 6}] polyhedra.
Improved Size-Tunable Synthesis of Monodisperse Gold Nanorods through the Use of Aromatic Additives
We report an improved synthesis of colloidal gold nanorods (NRs) by using aromatic additives that reduce the concentration of hexadecyltrimethylammonium bromide surfactant to similar to 0.05 M as opposed to 0.1 M in well-established protocols. The method optimizes the synthesis for each of the 11 additives studied, allowing a rich array of monodisperse gold NRs with longitudinal surface plasmon resonance tunable from 627 to 1246 nm to be generated. The gold NRs form large-area ordered assemblies upon slow evaporation of NR solution, exhibiting liquid crystalline ordering and several distinct local packing motifs that are dependent upon the NR's aspect ratio. Tailored synthesis of gold NRs with simultaneous improvements in monodispersity and dimensional tunability through rational introduction of additives will not only help to better understand the mechanism of seed-mediated growth of gold NRs but also advance the research on plasmonic metamaterials incorporating anisotropic metal nanostructures.
Nuclear Data Sheets for A=37
Nuclear spectroscopic information for experimentally investigated nuclides of mass 37 (Na, Mg, Al, Si, P, S, Cl, Ar, K, Ca) has been evaluated. The principal sources of the 'adopted levels' presented for nuclides close to the stability line are Endt's evaluations (1990En08, 1978En02). The data sets for reactions and decays, including all available gamma-ray data, are based mostly on the original literature. There are no data available for the excited states in {sup 37}Na, {sup 37}Mg, {sup 37}Al; and for {sup 37}Si, only one excited state is known.
Experimental Statistics of Droplet Trajectory and Air Flow during Aerodynamic Fragmentation of Liquid Drops.
Abstract Not Provided