28 research outputs found
Failure mechanisms in lithium silicon batteries
No full textLithium silicon (Li-Si) batteries offer more than ten times the theoretical specific capacity compared to current lithium ion battery technologies, by using a silicon anode. In practice however, the cycle life of Li-Si batteries is very limited. The large volume change of the silicon anode is known to be the main reason for this. Research on the volume changes during varying cell cycles and voltages is presented in this thesis and an experimental set up for a quasi in situ study of the SEI layer is suggested. Cycling tests with an amorphous silicon thin film of 220 nm deposited using magnetron sputtering on a copper foil current collector confirmed that the major cause of capacity loss is swelling of the silicon during lithiation, causing the silicon to detach from the current collector and resulting in significant capacity loss. Increasing the lower cut off voltage from 0 V to 0.2 V resulted in a slight improvement of cycle life. Silicon detachment also decreased as determined by SEM images. EFTEM and EDX mapping showed a clear split between a partially lithiated silicon layer on the surface and a pure silicon layer on the current collector side. It can be concluded that discharging Li-Si batteries to 0.2 V instead of 0 V is a promising method to reduce the swelling of silicon during lithiation.HREMQuantum NanoscienceApplied Science
Torsion of undescended testis
No full textWe report the case of a three year old boy with torsion of undescended
testis, within the inguinal canal, which is a very rare entity. The
pathophysiology and the management is discussed in detail
The Square-Free Sieve over Number Fields
No full textAbstractFor E an elliptic curve over a number field K, we give a lower bound, conditional on the "parity conjecture," for the number of quadratic twists of E whose Mordell-Weil rank is at least two. The main tool is a sieve-theoretic estimate of the number of square-free values of a homogeneous binary form. The results are a direct extension of those found by the author and B. Mazur (J. Amer. Math. Soc.4, 1991, 1-23)
A constructive proof of a unimodular transformation theorem for simplices
No full textMatrices;Linear Programming;Integer Programming
Comparison of Particle-Associated Bacteria from a Drinking Water Treatment Plant and Distribution Reservoirs with Different Water Sources
No full textThis study assessed the characteristics of and changes in the suspended particles and the associated bacteria in an unchlorinated drinking water distribution system and its reservoirs with different water sources. The results show that particle-associated bacteria (PAB) were present at a level of 0.8–4.5?×?103 cells ml?1 with a biological activity of 0.01–0.04?ng l?1 ATP. Different PAB communities in the waters produced from different sources were revealed by a 16S rRNA-based pyrosequencing analysis. The quantified biomass underestimation due to the multiple cells attached per particle was???85%. The distribution of the biologically stable water increased the number of cells per particle (from 48 to 90) but had minor effects on the PAB community. Significant changes were observed at the mixing reservoir. Our results show the characteristics of and changes in suspended PAB during distribution, and highlight the significance of suspended PAB in the distribution system, because suspended PAB can lead to a considerable underestimation of biomass, and because they exist as biofilm, which has a greater mobility than pipe-wall biofilm and therefore presents a greater risk, given the higher probability that it will reach the customers’ taps and be ingested.Water ManagementCivil Engineering and Geoscience
annabellisa/PLANTPOPNET_genetics: PLANTPOPNET data and scripts v1.2
No full textDescription: R scripts for processing and analysing genetic and demographic data from Plantago lanceolata. Used in population genetics research by Annabel Smith and Yvonne Buckley, with the PLANTPOPNET network.
Author: Annabel Smith, except where indicated within the script.
Manuscript: Smith A.L., Hodkinson T.R., Villellas J., Catford J.A., Csergő A.M., Blomberg S.P., Crone E.E., Ehrlén J., Garcia M.B., Laine A.-L., Roach D.A., Salguero-Gómez R., Wardle G., Childs D.Z., Elderd B.D., Finn A., Munné-Bosch S., Baudraz M.E.A., Bódis J., Brearley F.Q., Bucharova A., Caruso C.M., Duncan R.P., Dwyer J.M., Gooden B., Groenteman R., Hamre L.N., Helm A., Kelly R., Laanisto L., Lonati M., Moore J.L., Morales M., Olsen S.L., Pärtel M., Petry W.K., Ramula S., Rasmussen P.U., Enri S.R., Roeder A., Roscher C., Saastamoinen M., Tack A.J.M., Töpper J.P., Vose G.E., Wandrag E.M., Wingler A. & Buckley Y.M. (2020). Global gene flow releases invasive plants from environmental constraints on genetic diversity. Proceedings of the National Academy of Sciences USA, www.pnas.org/cgi/doi/10.1073/pnas.1915848117
License: PLANTPOPNET genetics by Annabel Smith is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License. Based on a work at https://github.com/annabellisa/PLANTPOPNET_genetics
Modulation of nitrosative stress by S-nitrosoglutathione reductase is critical for thermotolerance and plant growth in arabidopsis
No full textNitric oxide (NO) is a key signaling molecule in plants. This analysis of Arabidopsis thaliana HOT5 (sensitive to hot temperatures), which is required for thermotolerance, uncovers a role of NO in thermotolerance and plant development. HOT5 encodes S-nitrosoglutathione reductase (GSNOR), which metabolizes the NO adduct S-nitrosoglutathione. Two hot5 missense alleles and two T-DNA insertion, protein null alleles were characterized. The missense alleles cannot acclimate to heat as dark-grown seedlings but grow normally and can heat-acclimate in the light. The null alleles cannot heat-acclimate as light-grown plants and have other phenotypes, including failure to grow on nutrient plates, increased reproductive shoots, and reduced fertility. The fertility defect of hot5 is due to both reduced stamen elongation and male and female fertilization defects. The hot5 null alleles show increased nitrate and nitroso species levels, and the heat sensitivity of both missense and null alleles is associated with increased NO species. Heat sensitivity is enhanced in wild-type and mutant plants by NO donors, and the heat sensitivity of hot5 mutants can be rescued by an NO scavenger. An NO-overproducing mutant is also defective in thermotolerance. Together, our results expand the importance of GSNOR-regulated NO homeostasis to abiotic stress and plant development
Achieving high molecular conversion efficiency via a magnetic field pulse train
No full textWe investigate the process of production of ultracold molecules in an ultracold bosonic system with particle interaction via designing a magnetic field pulse train near a Feshbach resonance. This technique offers a high conversion efficiency up to 100% by tuning the pulse durations appropriately. The molecular conversion efficiency is related to the duration of each pulse, which can be derived analytically. It is found that the conversion efficiency is insensitive to the first pulse, highly sensitive to the second one, and very insensitive to the third one. The effects of particle interaction on conversion process are discussed as well.Physics, Condensed MatterSCI(E)EI0ARTICLE6null8
Electron acceleration sites in a large-scale coronal structure
No full textRadio observations and interplanetary particle measurements have
shown that even in the absence of conspicuous violent processes in the low
atmosphere (such as Hα flares) electrons are accelerated in the corona, most
likely at higher altitudes than during flares (≥0.5 R above the
photosphere). The paper presents direct evidence on the acceleration sites from
a case study of radio, visible light and soft X-ray observations: electrons are
repeatedly accelerated in a large-scale coronal structure which is identified
with a streamer in coronographic observations. Energy is simultaneously
released in an active region near the base of the structure and at a height of
∼1 R , over several hours before the large-scale structure erupts. Energy
input is observed in at least two emerging active regions underneath the
streamer. The coronal configuration is three-dimensional, overlying a whole
quadrant of the Sun. It is argued that the observations trace multiple sites of
energy release presumably in current sheets embedded within the streamer, in
agreement with scenarios developed for the acceleration of electrons seen in
the corona and at 1 AU, and for the evolution of large-scale coronal structures
towards eruption
The Prospects for Coal: Global Experience and Implications for Energy Policy
No full textThis paper argues that coal and its industry is promising. It is found that the Western European (including the British) case has been misunderstood and the US case shows a developing coal industry under increasing levels of environmental pressure. The demonstration of the declining emissions intensity of coal provides an additional mean of reconciling the development of the coal industry with the environment. In the long term the enforcement of environmental regulations can benefit the coal industry in several ways, and the alternatives to coal are not yet available in a sufficiently large scale. Based on the positive prospects of coal, issues related to climate change, clean coal technology and energy policy are discussed.
