1,322 research outputs found
NH\u3csub\u3e2\u3c/sub\u3e-Terminal analysis of the conidial proteins of N. crassa
NH2-Terminal analysis of the conidial proteins of N. crass
Geophysical monitoring of simulated clandestine graves using electrical and GPR methods: 0-3 years after burial
Efficient harvesting and storage of solar energy of an all-vanadium solar redox flow battery with a MoS2@TiO2 photoelectrode
Solar redox flow batteries constitute an emerging technology that provides a smart alternative for the capture and storage of discontinuous solar energy through the photo-generation of the discharged redox species employed in traditional redox flow batteries. Here, we show that a MoS2-decorated TiO2 (MoS2@TiO2) photoelectrode can successfully harvest light to be stored in a solar redox flow battery using vanadium ions as redox active species in both the catholyte and anolyte, and without the use of any bias. The MoS2@TiO2 photoelectrode achieved an average photocurrent density of ∼0.4 mA cm−2versus 0.08 mA cm−2 for bare TiO2, when tested for the oxidation of V4+ to V5+, attributed to a more efficient light harvesting and charge separation for the MoS2@TiO2 relative to TiO2. The designed solar redox flow cell exhibited an optimal overall solar-to-output energy conversion efficiency (SOEE) of ∼4.78%, which outperforms previously reported solar redox flow batteries. This work demonstrates the potential of the MoS2@TiO2 photoelectrode to efficiently convert solar energy into chemical energy in a solar redox flow battery, and it also validates the great potential of this technology to increase reliability in renewable energies
Concussion education in medical students studying in Scotland:an assessment of knowledge and future needs
Our experience in using magnetic resonance imaging (MRI) as an adjunct to mammography and ultrasound in assessing response to neoadjuvant chemotherapy
Open-circuit dissolution of platinum from the cathode in polymer electrolyte membrane water electrolysers
Platinum is the state-of-the-art catalyst for hydrogen evolution in polymer electrolyte membrane (PEM) water electrolysers; however, its stability has only been characterized to a limited extent in situ. This study measures platinum dissolving from the cathode during intermittent operation of a 3-electrode PEM electrolyser cell, using a differential pulse voltammetry technique that provided detection limits for platinum of less than 2 ng L−1. Water samples were periodically taken during on-off current cycling, and during periods of open-circuit voltage (OCV) platinum dissolution was detected when the cathode potential rose above 0.85 V NHE due to diffusion of oxygen from the anode. This reached a maximum dissolution rate at the highest cathode potential of 1.02 V NHE, and gradually decayed over a 90 h period. The average total amount of platinum dissolved per 90 h OCV period was estimated to be 152 ng cm−2 or 0.005% of the initial electrode catalyst mass. The dissolution mechanism was predicted to be the same as that occurring in PEM fuel cell cathodes, although being kinetically hindered in PEM electrolysers by the slow diffusion of oxygen from the anode to the cathode
Tracking internal temperature and structural dynamics during nail penetration of lithium-ion cells
Mechanical abuse of lithium-ion batteries is widely used during testing to induce thermal runaway, characterize associated risks, and expose cell and module vulnerabilities. However, the repeatability of puncture or ‘nail penetration’ tests is a key issue as there is often a high degree of variability in the resulting thermal runaway process. In this work, the failure mechanisms of 18650 cells punctured at different locations and orientations are characterized with respect to their internal structural degradation, and both their internal and surface temperature, all of which are monitored in real time. The initiation and propagation of thermal runaway is visualized via high-speed synchrotron X-ray radiography at 2000 frames per second, and the surface and internal temperatures are recorded via infrared imaging and a thermocouple embedded in the tip of the penetrating nail, respectively. The influence of the nail, as well as how and where it penetrates the cell, on the initiation and propagation of thermal runaway is described and the suitability of this test method for representing in-field failures is discussed
Breakdown of Scaling in the Nonequilibrium Critical Dynamics of the Two-Dimensional XY Model
The approach to equilibrium, from a nonequilibrium initial state, in a system
at its critical point is usually described by a scaling theory with a single
growing length scale, , where z is the dynamic exponent
that governs the equilibrium dynamics. We show that, for the 2D XY model, the
rate of approach to equilibrium depends on the initial condition. In
particular, if no free vortices are present in the
initial state, while if free vortices are
present.Comment: 4 pages, 3 figure
Low-temperature, high-density magneto-optical trapping of potassium using the open 4S-5P transition at 405 nm
We report the laser cooling and trapping of neutral potassium on an open
transition. Fermionic 40K is captured using a magneto-optical trap (MOT) on the
closed 4S-4P transition at 767 nm and then transferred, with unit efficiency,
to a MOT on the open 4S-5P transition at 405 nm. Because the 5P state has a
smaller line width than the 4P state, the Doppler limit is reduced. We observe
temperatures as low as 63(6) microkelvin, the coldest potassium MOT reported to
date. The density of trapped atoms also increases, due to reduced temperature
and reduced expulsive light forces. We measure a two-body loss coefficient of 2
x 10^-10 cm^3/s, and estimate an upper bound of 8x10^-18 cm^2 for the
ionization cross section of the 5P state at 405 nm. The combined temperature
and density improvement in the 405 nm MOT is a twenty-fold increase in phase
space density over our 767 nm MOT, showing enhanced pre-cooling for quantum gas
experiments. A qualitatively similar enhancement is observed in a 405 nm MOT of
bosonic 41K.Comment: 8 pages, 8 figures, 1 tabl
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