35 research outputs found
Manganese(III) complexes of 1,2-bis(2-pyridinecarboxamido)benzene: synthesis, spectra, and electrochemistry
No full textThe synthesis and solution properties of the high-spin (μeff.= 4.78-4.86 at 298 K) manganese(III) complexes [Mn(bpb)X][X = Cl-, N3-, or SCN-; H2bpb = 1,2-bis(2-pyridinecarboxamido)benzene], are described. The brown crystalline complexes display ligand-to-metal charge-transfer transitions at ca. 430 nm, while in the near-infrared region crystal-field transitions are observed. In N,N-dimethylformamide solution the complexes exhibit a quasi-reversible MnIII-MnII couple [E298°-0.03 to + 0.03 V vs. saturated calomel electrode (s.c.e.)]. The complexes [Mn(bpb)Cl] and [Mn(bpb)(N3)] display an additional quasi-reversible MnIV-MnIII couple [E298°+0.87 (Cl-); + 0.49 V (N3-)vs. s.c.e.]
Iodosylbenzene Oxidation of Alkanes, Alkenes, and Sulfides Catalyzed by Binuclear Non-heme Iron Systems: Comparison of Non-heme Iron Versus Heme Iron Oxidation Pathways
No full textIodosylbenzene Oxidation of Alkanes, Alkenes, and
Sulfides Catalyzed by Binuclear Non-heme Iron
Systems: Comparison of Non-heme Iron Versus
Heme Iron Oxidation Pathway
Skirting the oxo-wall: characterization and catalytic reactivity of binuclear Co2+/3+ 1,2-bis(2-hydroxybenzamido)benzene complexes with comparison to their isostructural Fe2+/3+ analogs. Implications of d-electron count on oxygen atom transfer catalysis
No full textThe micro-environmental impact of volatile organic compound emissions from large-scale assemblies of people in a confined space
No full textLarge-scale assemblies of people in a confined space can exert significant impacts on the local air chemistry due to human emissions of volatile organics. Variations of air-quality in such small scale can be studied by quantifying fingerprint volatile organic compounds (VOCs) such as acetone, toluene, and isoprene produced during concerts, movie screenings, and sport events (like the Olympics and the World Cup). This review summarizes the extent of VOC accumulation resulting from a large population in a confined area or in a small open area during sporting and other recreational activities. Apart from VOCs emitted directly from human bodies (e.g., perspiration and exhaled breath), those released indirectly from other related sources (e.g., smoking, waste disposal, discharge of food-waste, and use of personal-care products) are also discussed. Although direct and indirect emissions of VOCs from human may constitute ��1% of the global atmospheric VOCs budget, unique spatiotemporal variations in VOCs species within a confined space can have unforeseen impacts on the local atmosphere to lead to acute human exposure to harmful pollutants. (C) 2016 Elsevier Inc All rights reserved.The corresponding author (KHK) acknowledges support from a National Research Foundation of Korea (NRF) grant funded by the Ministry of Education, Science and Technology (MEST) (No. 2006-0093848) and by the Cooperative Research Program for Agriculture Science & Technology Development (Project title: Study on model development to control odor from hog barn, Project No. 11010521), Rural Development Administration, Republic of Korea
Engineering FEA Sintering Model Development for Metal Supported SOFC
No full textIn a collaboration between Ceres Power and Lancaster University, funded by Innovate UK, an engineering FEA model is being developed to further understand the manufacturing processes, such as the densification of the ceria based electrolyte. In these models material properties, such as the Thermal Expansion Coefficient, Young’s Modulus, layer densification rates and creep are critical inputs. These properties, when interacting with the applied thermal processes, give rise to stresses within the layers which can result in permanent deformation and residual stresses at the end of the process steps at room temperature. A deep analytical understanding of these material-process interactions can be used to optimise sintering time, energy usage, residual part stresses or distortion in a rapid and low cost way through the use of validated CAE models. Results will be presented from the modelling techniques for an example metal supported SOFC to demonstrate the importance of the above mentioned properties. Sensitivity study results will also be presented to show the impact of variability of the manufacturing process
Discovery of the zeroth law of helicity spectrum in the pre-inertial range of wall turbulence
No full textWe report an unprecedented existence of the zeroth law of helicity spectrum (i.e., the helicity spectrum becomes independent of the wavenumber) in the transition from production range to inertial range, herein termed the pre-inertial range, of wall turbulence. The zeroth law is explained by the superposition effect of the forward joint cascade of energy and helicity caused by twisting and stretching of wall-attached superstructures in an equilibrium layer. The phenomenological model perfectly predicts the zeroth law in the pre-inertial range. Experimental data support the existence of the zeroth law. © 2022 Author(s)
Fluvial instabilities
No full textFluvial instabilities originate from an interplay between the carrier fluid and the erodible loose boundary at their interface, manifesting a variety of sedimentary architectures with length scales spanning from a few millimeters to hundreds of meters. This review sheds light on the current state-of-the-science of the subject, explaining the fluvial instabilities from three broad perspectives. They are micro-scale, meso-scale, and macro-scale instabilities. The interactions between the near-bed hydrodynamics and the sediment dynamics in generating various kinds of instabilities, including their natures and driving mechanisms, are thoroughly appraised in the light of laboratory experimental results, field observations, and theoretical backgrounds. Besides, this review addresses the current challenges, delineating key points as a future research scope. © 2020 Author(s)
: A new perspective
No full textThe law of the wall, regarded as one of the very few pieces of turbulence hypothesis, predicts the mean-velocity profile (MVP) in a wall-bound flow. For about nine decades, the underlying physics of the law is deemed to be governed by an ad hoc mixing-length hypothesis. Here, we seek the origin of the law, for the first time, with the aid of a new hypothesis, which we call the mixing-instability hypothesis. The hypothesis unveils the previously unknown universal scaling behavior for the amplitude of turbulent ripples or waves (that cause spontaneous stretching and shrinking of turbulent eddies) within the overlap layer and accurately maps the experimental data of the MVPs for moderate to extremely large Reynolds numbers. This study offers a new mechanism of the momentum transfer in a turbulent wall-bound flow, calling for a revision of the conventional mixing-length hypothesis, which has persisted in standard textbooks on turbulence for many decades. © 2020 Author(s)
