Effects of Molecular and Electronic Structures in CoOx/CeO2 Catalysts on NO Reduction by CO
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99 GENERAL AND MISCELLANEOUS↗
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Effect of polymer structure and material properties on mechanochemical reaction environments for polymer recycling
Plastic waste accumulation necessitates innovative recycling approaches to achieve sustainability goals. Mechanochemical depolymerization offers a solvent-free, energy-efficient route to convert polymers into valuable monomers. In addition to their chemical properties, the way that polymers absorb kinetic energy is a key parameter of any mechanochemical process. This perspective explores the principles underpinning mechanochemical recycling, emphasizing how deformation and localized transient heating mediate energy transfer between impacts and localized excitations. Key factors such as polymer crystallinity, molecular weight, viscoelasticity, and thermal effects are analyzed to elucidate their role in energy transfer mechanisms during ball milling. This work establishes a foundational framework for the design and optimization of mechanochemical recycling by connecting polymer response to mechanical energy with the intention to improve depolymerization efficiency. Future research opportunities are outlined to advance the integration of polymer science and mechanochemistry for scalable, sustainable plastic upcycling.
ball mill↗
Surface topographical effects on the structural growth of thick sputtered metal and alloy coatings
Thick sputtered S-Monel, silver, and 304 stainless steel coatings were deposited on mica and metal substrates with various surface finishes to investigate the structural growth of the coating by scanning electron microscopy. The geometry and the surface structure of the nodules are characterized. Compositional changes within the coating were analyzed by X-ray dispersion microscopy. Defects in the surface finish (i.e., scratches, inclusions, etc.) act as preferential nucleation sites and form isolated and complex nodules and various surface overgrowths in the coating. The nodule boundaries are very vulnerable to chemical etching and these nodules do not disappear after full annealing. Further, they have undesirable effects on mechanical properties; cracks are initiated at the nodules when the coating is stressed by mechanical forces. These effects are illustrated by micrographs. Nodular growth within a coating can be minimized or eliminated by reducing the surface roughness.
Spalvins, T.↗
Effects of nuclear structure and quantum interference on diffractive vector meson production in ultra-peripheral nuclear collisions
Here we study diffractive vector meson production in ultra-peripheral collisions (UPCs) of heavy nuclei, utilizing a theoretical framework based on the Color Glass Condensate (CGC) formalism. We focus on Au + Au, U + U, Ru + Ru, Zr + Zr, and Pb + Pb collisions, examining the transverse momentum dependence of vector meson production cross-sections and co s(2ΔΦ)asymmetries in the decay product distributions to explore the role of nuclear geometry. The angular modulation is due to the linear polarization of the incoming photons and quantum interference effects. We extract nuclear radii and find them to be consistent with experimental data from the STAR collaboration. The amplitudes of the cos(2ΔΦ)modulation in the cross-section and the extracted radii depend on the nuclear geometry. This dependence is dominated by the geometry-dependent variation of the minimum impact parameter required for ultra-peripheral collisions.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Effects of atmospheric structure on radiative heating for Jupiter entry probe
New estimates of the radiative heat load to a Jupiter entry probe have been obtained for revised models of Jupiter's atmosphere based on the latest data from Pioneer 10 and 11 missions and earth-based experiments. The new estimates of the radiative heat load are compared with results obtained for the previous atmospheric models. The changes in Jupiter's atmospheric models cause a substantial reduction in the radiative heat load for the atmosphere denoted as 'cool', but only moderate reductions for the atmospheres denoted as 'nominal' and 'warm'. Results are also presented showing the effects of inertial entry angle for off-equatorial entries in the revised model atmospheres.
Sutton, K.↗
Interaction strength and model geometry effects on the structure of crossing-shock wave/turbulent boundary-layer interactions
The flowfield structure of a range of symmetric crossing-shock wave/turbulent boundary-layer interactions of varying strength is presented. The test geometry, consisting of a symmetric pair of opposing sharp fins at angle of attack, alpha, mounted to a flat plate, is studied experimentally for a range of alpha from 7 to 15 degrees at Mach numbers of 3 and 4. Results reveal that the basic flowfield shock structure remains similar in nature over the range of interaction strengths examined, with the only changes being in the scale and location of the various features present. The separated flow regions are classified as being either completely or partially separated, the completely separated case being the one in which the entire incoming boundary layer separates from the plate surface. For the current experiments, all but the weakest of the interactions exhibited complete boundary layer separation. Finally, the effects of model geometry are analyzed by comparing data for shock generators of varying lengths, with the results showing no evidence of upstream influence due to the shock generator trailing edges.
Garrison, T. J.↗
Properties of dust in the Martian atmosphere and its effect on temperature structure
Data from the Viking lander imaging experiment and the IRIS experiment on board the Mariner 9 Orbiter are used to develop a one-dimensional radiative-convective model to describe the Mars temperature profile. Photography was employed to determine the optical depth, mean size, shape, visible absorption coefficient, and vertical distribution of aerosols in the Mars atmosphere. The calculation procedures are outlined, particularly for the particle size distribution function, which indicated a cross-sectional average particle radius of 2.5 microns. Dust-free conditions in the atmosphere near the equator and at lower altitudes permit full surface absorption of sunlight and subsequent adiabatic lapse rates. Difficulties were encountered in accurately modeling temperature profiles to fit Viking lander data, and resultant variations are attributed to effects of both suspended dust particles and large scale circulation.
Pollack, J. B.↗
Layer-Dependent Pressure Effect on the Electronic Structure of 2D Black Phosphorus
Through infrared spectroscopy, we systematically study the pressure effect on electronic structures of few-layer black phosphorus (BP) with layer number ranging from 2 to 13. We reveal that the pressure-induced shift of optical transitions exhibits strong layer dependence. In sharp contrast to the bulk counterpart which undergoes a semiconductor to semimetal transition under ~1.8 GPa, the band gap of 2 L increases with increasing pressure until beyond 2 GPa. Meanwhile, for a sample with a given layer number, the pressure-induced shift also differs for transitions with different indices. Through the tight-binding model in conjunction with a Morse potential for the interlayer coupling, this layer- and transition-index-dependent pressure effect can be fully accounted. Our study paves a way for versatile van der Waals engineering of two-dimensional BP.
2-dimensional systems↗
Gravitational Effects on Cellular Flame Structure
An experimental investigation has been conducted of the effect of gravity on the structure of downwardly propagating, cellular premixed propane-oxygen-nitrogen flames anchored on a water-cooled porous-plug burner. The flame is subjected to microgravity conditions in the NASA Lewis 2.2-second drop tower, and flame characteristics are recorded on high-speed film. These are compared to flames at normal gravity conditions with the same equivalence ratio, dilution index, mixture flow rate, and ambient pressure. The results show that the cellular instability band, which is located in the rich mixture region, changes little under the absence of gravity. Lifted normal-gravity flames near the cellular/lifted limits, however, are observed to become cellular when gravity is reduced. Observations of a transient cell growth period following ignition point to heat loss as being an important mechanism in the overall flame stability, dominating the stabilizing effect of buoyancy for these downwardly-propagating burner-anchored flames. The pulsations that are observed in the plume and diffusion flame generated downstream of the premixed flame in the fuel rich cases disappear in microgravity, verifying that these fluctuations are gravity related.
Dunsky, C. M.↗
The effect of aerodynamic and structural detuning on turbomachine supersonic unstalled torsional flutter
The effects of alternate-blade structural detuning and adjacent-blade alternate-circumferential-spacing aerodynamic detuning on the supersonic unstalled torsional flutter stability of a turbomachine rotor are investigated analytically. An unsteady aerodynamic model employing influence coefficients is constructed for the case of a flat-plate-airfoil cascade in torsion-mode harmonic oscillation in a supersonic inviscid isentropic adiabatic irrotational perfect-gas inlet flow with a subsonic leading-edge locus. The influence coefficients and equations of motion are derived; the model is verified by applying it to the 12-blade cascade-B flow geometry studied by Verdon and McCune (1975); and the results are presented graphically. It is found that the rotor can be stabilized over the entire reduced frequency range by applying a combination of structural and aerodynamic detuning as the passive flutter-control mechanism.
Hoyniak, D.↗
Monolayer TiS 2 Nanosheets on Au(111)–Structural Characterization and Effect of Edge Stability for Shape Control
Transition metal dichalcogenides are promising alternatives to noble metal catalysts, e.g., for (photo-)activation of greenhouse gases or hydrogenations. Herein, a direct synthetic route for 2D TiS 2 nanosheets on Au(111) by titanium deposition in the presence of a mild, organic, non-oxidizing sulfur source is presented. High-resolution scanning tunneling microscopy (STM) is used to gain atomic-level insights into the TiS 2 nanosheet morphology. In contrast to the literature, this protocol gains mostly hexagonal and truncated triangular nanosheets with an increased edge contrast in STM, analog to metallic edge states in MoS 2 . Synchrotron-based photoelectron spectroscopy allows insights into compositional details, specifically to distinguish different S sites on the TiS 2 sheets and other S species on the sample. Further, a minimum size is identified (9 S atoms side length), which underlines the importance of moiré reconstructions for stress relief. The TiS 2 sheets coexist with [Au]Ti 1 S 3 clusters, in which a single gold atom is alloyed into the surface and capped by three S atoms. Together with the finding of a critical sheet size, this points toward on-surface Ostwald ripening as a relevant process in the sheet formation. Ab-initio calculations (density functional theory) underscore that the chemical potential of S is an essential descriptor to maintain shape control.
2D nanomaterials↗
Solar Energy Research Institute for India and the United States (SERIIUS): Lessons and Results from a Binational Consortium
This book describes the development, functioning, and results of a successful binational program to promote significant scientific advances in Earth-abundant photovoltaics (PV) and concentrated solar power (CSP), advanced process/manufacturing technologies, multiscale modeling and reliability testing, and analysis of integrated solar energy systems. SERIIUS is a consortium between India and the United States dedicated to developing new solar technologies and assessing their potential impact in the two countries. The consortium consists of nearly 50 institutions including academia, national laboratories, and industry, with the goal of developing significant new technologies in all areas of solar deployment. In addition, the program focused on workforce development through graduate students, post-doctoral students, and an international exchange program. Particular emphasis was placed on the following efforts: creating disruptive technologies in PV and CSP through high-impact fundamental and applied research and development (R&D); identifying and quantifying the critical technical, economic, and policy issues for solar energy development and deployment in India; overcoming barriers to technology transfer by teaming research institutions and industry in an effective project structure; building a new platform for binational collaboration using a formalized R&D project structure, along with effective management, coordination, and decision processes; creating a sustainable network and workforce development program from which to build large collaborations and fostering a collaborative culture and outreach programs. This includes using existing and new methodologies for collaboration based on advanced electronic and web-based communication to facilitate functional international teams. The book summarizes the general lessons learned from these experiences.
14 SOLAR ENERGY↗
High-Temperature Firing Effect on the Structure and Dielectric Properties of (0.5) La{sub 0.8}Sr{sub 0.2}MnO{sub 3} (LSMO) + (0.5) Ba{sub 0.5}K{sub 0.5}TiO{sub 3} (BKT) Composite
A composite of two perovskite materials namely Ba{sub 0.5}K{sub 0.5}TiO{sub 3}[BKT] and La{sub 0.8}Sr{sub 0.2}MnO{sub 3} [LSMO] was prepared via solid state reaction route. Analysis of the XRD data confirmed the single-phased crystalline cubic structure with assigned space group Pm-3m though parent compounds, i.e., BKT and LSMO, were cubic and rhombohedral structured, respectively, having space groups Pm-3m and R3c. The single phase of the composite is found to occur due to higher heat treatment. Retvield refinement of the XRD data confirmed the structure and other essential parameters regarding cubic structure. The Raman studies displayed active modes corresponding to the BKT (Pm-3m) phase. The surface morphology studies confirmed an increase in average particle size, and the energy dispersive analysis of X-ray (EDAX) technique revealed the presence of all the constituents of the material under investigation. The dielectric studies were carried out, and the sample was found to exhibit appreciable dielectric behaviour with a lower loss value. Impedance analysis revealed the non-Debye behaviour of the resultant composite and distribution of relaxation throughout the material. Resistivity measurement conveyed that incorporation of the BKT phase in the metallic phase of LSMO leads the composite to exhibit an insulating nature.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
The Influence of Warm abc-Pressing on the Structure and Mechanical Properties of Stable Chromium-Nickel-Molybdenum Steel
The structure and properties of the 17Cr13Ni3Mo0.01C stable austenitic steel subjected to high-temperature plastic deformation by the abc-pressing (multiaxial forging) are investigated in the temperature range from 800 to 600°С. The results of investigations demonstrate that after the abc-pressing the steel has a single-phase austenitic ultrafine-grained structure with the size of its elements (grains and subgrains) of (200 ± 140) nm. The formation of the ultrafine-grained state increases the strength properties (0.2 proof stress increases threefold) and decreases the elongation value of the steel at room temperature compared to the coarse-grained specimens. An analysis of the contributions from hardening during abc-pressing evidences in favor of the strength improvement being primarily due to the grain refinement; it is well described by the Hall–Petch relationship. In this case steel with ultrafine-grained austenitic structure exhibits an effect of structural superplasticity at the temperatures T > 750°С: the elongation value at Т = 800°С is found to be 180%.
36 MATERIALS SCIENCE↗
Approximate methodology to account for effects of coherent structures on sediment entrainment in RANS simulations with a movable bed and applications to pier scour
Not Available
Cheng, Zhengyang (ORCID:0000000216060767)↗