462 research outputs found
Application of digital analysis of MSS to agro-environmental studies
Topics of investigation include infrared analysis of vegetation canopies, urban/rural albedo studies, analysis of Field Spectrometer System (ESS) observations, geometric and radiometric processing techniques of aircraft MSS data, and the use of LANDSAT MSS observations to map wetlands and snow cover
Structure solution of metal-oxide Li battery cathodes from simulated annealing and lithium NMR spectroscopy
Discerning
the arrangement of transition metal atoms in LiĀ[Ni<sub><i>x</i></sub>Mn<sub><i>y</i></sub>Co<sub><i>z</i></sub>]ĀO<sub>2</sub> cathode materials has remained an
open problem for many years despite the commercial importance of some
stoichiometries and the even more promising characteristics of others.
We present a method for structural determination in this class of
cathode materials. A simple definition of the total energy, based
on the chemical principle of electroneutrality, is used in combination
with a simulated annealing algorithm to generate model structures.
The method reproduces the well-known structure of LiĀ[Li<sub>1/3</sub>Mn<sub>2/3</sub>]ĀO<sub>2</sub> and produces structures of the disordered
LiĀ[Ni<sub><i>x</i></sub>Mn<sub><i>x</i></sub>Co<sub>1ā2<i>x</i></sub>]ĀO<sub>2</sub> phases (where <i>x</i> = 0.02, 0.1, 0.33) that are verified by detailed <sup>7</sup>Li NMR spectra. For each LiĀ[Ni<sub><i>x</i></sub>Mn<sub><i>x</i></sub>Co<sub>1ā2<i>x</i></sub>]ĀO<sub>2</sub> phase, the solution is found to be heavily disordered,
yet retaining significant ion pairing. Since the underlying notion
of favoring charge-neutral regions is generic, we anticipate its utility
in a much broader family of materials
The permafrost carbon inventory on the Tibetan Plateau : a new evaluation using deep sediment cores
Acknowledgements We are grateful for Dr. Jens Strauss and the other two anonymous reviewers for their insightful comments on an earlier version of this MS, and appreciate members of the IBCAS Sampling Campaign Teams for their assistance in field investigation. This work was supported by the National Basic Research Program of China on Global Change (2014CB954001 and 2015CB954201), National Natural Science Foundation of China (31322011 and 41371213), and the Thousand Young Talents Program.Peer reviewedPostprin
Deep soil water-use determines the yield benefit of long-cycle wheat
Wheat production in southern Australia is reliant on autumn (April-May) rainfall to germinate seeds and allow timely establishment. Reliance on autumn rainfall can be removed by sowing earlier than currently practiced and using late summer and early autumn rainfall to establish crops, but this requires slower developing cultivars to match life-cycle to seasonal conditions. While slow-developing wheat cultivars sown early in the sowing window (long-cycle), have in some cases increased yield in comparison to the more commonly grown fast-developing cultivars sown later (short-cycle), the yield response is variable between environments. In irrigated wheat in the sub-tropics, the variable response has been linked to ability to withstand water stress, but the mechanism behind this is unknown. We compared short- vs. long-cycle cultivars Ć time of sowing combinations over four seasons (2011, 2012, 2015, and 2016) at Temora, NSW, Australia. Two seasons (2011 and 2012) had above average summer fallow (December-March) rain, and two seasons had below average summer fallow rain (2015 and 2016). Initial plant available water in each season was 104, 91, 28, and 27 mm, respectively. Rainfall in the 30 days prior to flowering (approximating the critical period for yield determination) in each year was 8, 6, 14, and 190 mm, respectively. We only observed a yield benefit in long-cycle treatments in 2011 and 2012 seasons where there was (i) soil water stored at depth (ii) little rain during the critical period. The higher yield of long-cycle treatments could be attributed to greater deep soil water extraction (<1.0 m), dry-matter production and grain number. In 2015, there was little rain during the critical period, no water stored at depth and no difference between treatments. In 2016, high in-crop rainfall filled the soil profile, but high rainfall during the critical period removed crop reliance on deep water, and yields were equivalent. A simulation study extended our findings to demonstrate a median yield benefit in long-cycle treatments when the volume of starting soil water was increased. This work reveals environmental conditions that can be used to quantify the frequency of circumstances where long-cycle wheat will provide a yield advantage over current practice.The research undertaken as part of this project is made possible
by the significant contributions of growers through both trial
cooperation and the support of the GRDC (projects CSP00111,
CSP00178, CSP00183, 9175069, and a GRDC Grains Industry
Research Scholarship
Multi-layered Ruthenium-modified Bond Coats for Thermal Barrier Coatings
Diffusional approaches for fabrication of multi-layered Ru-modified bond coats for thermal
barrier coatings have been developed via low activity chemical vapor deposition and high activity
pack aluminization. Both processes yield bond coats comprising two distinct B2 layers, based on
NiAl and RuAl, however, the position of these layers relative to the bond coat surface is reversed
when switching processes. The structural evolution of each coating at various stages of the
fabrication process has been and subsequent cyclic oxidation is presented, and the relevant
interdiffusion and phase equilibria issues in are discussed. Evaluation of the oxidation behavior of
these Ru-modified bond coat structures reveals that each B2 interlayer arrangement leads to the
formation of Ī±-Al 2 O 3 TGO at 1100Ā°C, but the durability of the TGO is somewhat different and in
need of further improvement in both cases
A Polymer-Rich Quaternary Composite Solid Electrolyte for Lithium Batteries
All-solid-state batteries continue to grow as an alternative to replace the traditional liquid-based ones not only because they provide increased safety but also higher power and energy densities. However, current solid-state electrolytes are either ceramics that are brittle but highly conducting (e.g. Li0.33La0.55TiO3, LLTO) or polymer electrolytes that are poorly conducting but form flexible films with desired mechanical properties (e.g. Poly(ethylene oxide):Lithium bis(trifluoromethanesulfonyl)imide, PEO:LiTFSI). In this work, we have developed quaternary composite solid-state electrolytes (CSEs) to combine the benefits of the two types along with Succinonitrile (SN) as a solid plasticizer. CSEs with different compositions have been fully characterized over the whole compositional range. Guided by neural network simulation results it has been found that a polymer-rich CSE film gives the optimal ionic conductivity (>10ā3 S cmā1 at 55 Ā°C) and mechanical properties (Tensile strength of 16.1 MPa; Elongation-at-break of 2360%). Our solid-state coin-type cell which employs our in-house made cathode shows good cycling performance at C/20 and 55 Ā°C maintaining specific discharge capacity at 143.2 mAh gā1 after 30 cycles. This new approach of formulating quaternary CSEs is proven to give the best combination of properties and should be universal and be applied to other CSEs with different chemistry
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