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Stabilized,flat iron flames on a hot counterflow burner 总被引:1,自引:0,他引:1
Michelle McRae Philippe Julien Santino Salvo Samuel Goroshin David L. Frost Jeffrey M. Bergthorson 《Proceedings of the Combustion Institute》2019,37(3):3185-3191
Metal powder combustion has traditionally been studied to mitigate the risk of industrial accidents and to determine the contributions of metals as additives to the performance of energetic materials. Recently, there has been growing interest in exploring the potential of metal powders as recyclable, zero-carbon energy carriers as an alternative to the hydrocarbons known to contribute to climate change. The present work introduces, for the first time, a stabilized flat iron flame. The counterflow burner used in this work is comprised of an inverted ceramic nozzle which sits above, and is aligned axially with, a lower nozzle producing a laminar flow of particles suspended in an oxidizing gas. A stabilized methane flame sits inside the top nozzle and the hot combustion products impinge upon the two-phase flow from the bottom nozzle, creating a stagnation plane. Spherical iron powder, with 90% of the particles less than 2.5 µm in size, is pre-loaded into a piston and dispersed using mixtures of 30% and 40% oxygen balanced in argon. Flame speeds are measured using particle image velocimetry (PIV), while flame temperatures are determined using multicolour pyrometry. It is found that flame speeds range between 30 cm/s and 45 cm/s for both oxidizing mixtures. Despite having fuel loadings below stoichiometric concentrations, the observed particle combustion temperatures are close to the adiabatic flame temperature of the stoichiometric mixture, indicating combustion in the diffusion-controlled regime for these small particles. Finally, the independence of the flame speeds with respect to oxygen concentration suggests flame propagation in the discrete regime. 相似文献
84.
Jiaman Liu Yuqing Liu Xiaofeng He Bo Teng Jacqui M. McRae 《Molecules (Basel, Switzerland)》2021,26(9)
Valonea tannin is a natural product readily extracted from acorn shells that has been suggested to have potential skin whitening properties. This study investigated the tyrosinase inhibition activity of extracted valonea tannin and the associated structure–function activity. Nuclear magnetic resonance spectroscopy and molecular weight analysis with gel permeation chromatography revealed that valonea tannin could be characterized as a hydrolysable tannin with galloyl, hexahydroxydiphenoyl and open formed-glucose moieties and an average molecular weight of 3042 ± 15 Da. Tyrosinase inhibition assays demonstrated that valonea tannin was 334 times more effective than gallic acid and 3.4 times more effective than tannic acid, which may relate to the larger molecular size. Kinetic studies of the inhibition reactions indicated that valonea tannin provided tyrosinase inhibition through mixed competitive–uncompetitive way. Stern–Volmer fitted fluorescence quenching analysis, isothermal titration calorimetry analysis and in silico molecule docking showed valonea tannin non-selectively bound to the surface of tyrosinase via hydrogen bonds and hydrophobic interactions. Inductively coupled plasma-optical emission spectroscopy and free radical scavenging assays indicated the valonea tannin had copper ion chelating and antioxidant ability, which may also contribute to inhibition activity. These results demonstrated the structure–function activity of valonea tannin as a highly effective natural tyrosinase inhibitor that may have commercial application in dermatological medicines or cosmetic products. 相似文献
85.
Olivia F. McRae Qingbo Xia Stefanie Tjaberings Andr H. Grschel Chris D. Ling Markus Müllner 《Journal of polymer science. Part A, Polymer chemistry》2019,57(18):1890-1896
A templating method is developed to produce porous nanocrystalline anatase materials for negative electrodes in lithium‐ion batteries (LIBs). Amphiphilic diblock copolymers are used to generate template films with phase‐separated internal structure. Subsequent swelling with acidified titanium(IV) bis(ammonium lactato) dihydroxide (TALH) solution yielded structured hybrid films. Upon heating, the formation of TiO2 nanocrystals is induced, resulting in a three‐dimensional mesoporous structure directed by the bulk morphology of the polymer template. In comparison to commercial nanosized anatase, the structured anatase shows significant performance improvements in lithium‐ion coin cell batteries in terms of capacity, stability, and rate capability. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1890–1896 相似文献
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Ohne Zusammenfassung 相似文献
88.
In polarized low energy electron diffraction (PLEED) from W(100) at energies of 2 to 9 eV and incident angles 15°< θ < 45°, we observe a spin-splitting of the resonance sequence of peaks which converge on the (01) beam threshold. For θ>26° the peak splitting to peak width ratio is approximately constant while for decreasing θ≤26° it increases. An anomalous spin-up-only peak appears at small θ. The nature of the spin dependent splitting is discussed within the four-beam layer multiple scattering approximation. 相似文献
89.
In this paper, fixed point theorems of a nonlinear operator are developed, where the domain space C[[a,b],E] is different from the range, E, which is a metric space with partial order. An application of the fixed point theorem to a periodic boundary value problem with delay is also given. 相似文献
90.
Astringency is an important characteristic of red wine quality. The sensation is generally thought to be produced by the interaction of wine tannins with salivary proteins and the subsequent aggregation and precipitation of protein-tannin complexes. The importance of wine astringency for marketability has led to a wealth of research on the causes of astringency and how tannins impact the quality of the sensation, particularly with respect to tannin structure. Ultimately, the understanding of how tannin structure impacts astringency will allow the controlled manipulation of tannins via such methods as micro-oxygenation or fining to improve the quality of wines. 相似文献