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Thermal Spin Orbit Torque with Dresselhaus Spin Orbit Coupling
Based on the spinor Boltzmann equation, we obtain a temperature dependent
thermal spin-orbit torque in terms of the local equilibrium distribution
function in a two dimensional ferromagnet with Dresselhaus spin-orbit coupling.
We also derive the continuity equation of spin accumulation and spin current,
the spin diffusion equation in Dresselhaus ferromagnet, which contains the
thermal spin orbit torque under local equilibrium assumption. This temperature
dependent thermal spin-orbit torque originates from the temperature gradient
applied to the system. it is also sensitive to temperature due to the local
equilibrium distribution function therein. In the spin diffusion equation, we
can single out the usual spin-orbit torque as well as the spin transfer torque,
which is conceded to our previous results. Finally, we illustrate them by an
example of spin-polarized transport through a ferromagnet with Dresselhaus
spin-orbit coupling driven by temperature gradient, those torques including
thermal spin-orbit torque are demonstrated numerically.Comment: 19pages,6figure
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Asian monsoon dynamics at Dansgaard/Oeschger events 14-8 and Heinrich events 5-4 in northern China
A precisely 230Th-dated stalagmite oxygen isotope (δ18O) record from Dragon Cave,Shanxi Province, northern China, is proposed to reconstruct the millennial-scale changes of the East Asian Summer monsoon (EASM) during the period 53.2-1.3 ka BP (before 1950 AD). Our record shows significant millennial-scale oscillations that match in timing, characteristic, and duration with the Dansgaard/Oeschger (DO)30 events 14-8 and the Heinrich events 5, 4, 2, and 1 (hereafter H5, H4, H2 and H1) in high-latitude regions of the Northern Hemisphere. Especially, the H5 event is well
constrained from 48.1 to 46.9 ka BP with ten 230Th dates. Our chronology supports the NGRIP GICC05 timescale from 50 to 38 ka BP. A comprehensive comparison of the Chinese speleothem records from different regions along a north-south transect shows a unique trend towards more negative δ
18O values from 48.0 to 38.0 ka BP, suggesting that an intensified Asian summer monsoon (ASM) across the whole monsoonal China during the interval. We speculate that the joint effect, from both the cooling of the Southern Hemisphere and the enhanced land-sea temperature contrast
due to the rising summer insolation, is capable to regulate the low-latitude large-scale atmospheric circulation patterns and exert significant influences on the long-term
ASM variations during the middle of Marine Isotope Stage 3
Reaction Behaviors of Bagasse Modified with Phthalic Anhydride in 1âAllylâ3âMethylimidazolium Chloride with Catalyst 4âDimethylaminopyridine
The modification of lignocellulose with cyclic anhydrides could confer stronger hydrophilic properties to lignocellulose, which could be used in many industrial fields. To elucidate the modification mechanism of lignocellulose, bagasse was phthalated comparatively with its three main components in 1âallylâ3âmethylimidazolium chloride (AmimCl) using 4âdimethylaminopyridine as catalyst and phthalic anhydride as acylation reagent in the present study. From FTâIR and 2D HSQC analyses, the skeleton of bagasse and the fractions were not significantly changed during phthalation in AmimCl. 2D HSQC results suggested that the reactive hydroxyls in bagasse were partially phthalated, and the reactivity of the hydroxyls in anhydroglucose units followed the order Câ6 > Câ2 > Câ3. Similarly, the reactivity order of hydroxyls in anhydroxylose units was Câ2 > Câ3. For lignin, the predominant diesterification occurred during the homogeneous modification, and both aliphatic and aromatic hydroxyls were phthalated. The reactivity order of phenolic hydroxyls was SâOH > GâOH > HâOH, which was distinct from that without catalyst. In addition, it was found that the thermal stability of phthalated bagasse was affected by the disruption of cellulose crystallinity and the degradation of components. The thermal stability of the phthalated bagasse decreased upon chemical modification and regeneration
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