447 research outputs found
Un-equivalency Theorem between Deformed and undeformed Heisenberg-Weyl's Algebras
Two fundamental issues about the relation between the deformed
Heisenberg-Weyl algebra in noncommutative space and the undeformed one in
commutative space are elucidated. First the un-equivalency theorem between two
algebras is proved: the deformed algebra related to the undeformed one by a
non-orthogonal similarity transformation is explored; furthermore,
non-existence of a unitary similarity transformation which transforms the
deformed algebra to the undeformed one is demonstrated. Secondly the uniqueness
of realizing the deformed phase space variables via the undeformed ones is
elucidated: both the deformed Heisenberg-Weyl algebra and the deformed bosonic
algebra should be maintained under a linear transformation between two sets of
phase space variables which fixes that such a linear transformation is unique.
Elucidation of this un-equivalency theorem has basic meaning both in theory and
experiment.Comment: 12 page
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In Situ TEM Study of the Degradation of PbSe Nanocrystals in Air
PbSe
nanocrystals have attracted widespread attention due to a
variety of potential applications. However, the practical utility
of these nanocrystals has been hindered by their poor air stability,
which induces undesired changes in the optical and electronic properties.
An understanding of the degradation of PbSe nanocrystals when they
are exposed to air is critical for improving the stability and enhancing
their applications. Here, we use in situ transmission electron microscopy
(TEM) with an environmental cell connected to air to study PbSe nanocrystal
degradation triggered by air exposure. We have also conducted a series
of complementary studies, including in situ environmental TEM study
of PbSe nanocrystals exposed to pure oxygen and PbSe nanocrystals
in H2O using a liquid cell, and ex situ experiments, such
as O2 plasma treatment and thermal heating of PbSe nanocrystals
under different air exposure. Our in situ observations reveal that
when PbSe nanocrystals are exposed to air (or oxygen) under electron
beam irradiation, they experience a series of changes, including shape
evolution of individual nanocrystals with the cuboid intermediates,
coalescence between nanocrystals, and formation of PbSe thin films
through drastic solid-state fusion. Further studies show that the
PbSe thin films transform into an amorphous Pb rich phase or eventually
pure Pb, which suggest that Se reacts with oxygen and can be evaporated
under electron beam illumination. These various in situ and ex situ
experimental results indicate that PbSe nanocrystal degradation in
air is initiated by the dissociation and removal of ligands from the
PbSe nanocrystal surface
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Revealing of the Activation Pathway and Cathode Electrolyte Interphase Evolution of Li-Rich 0.5Li2MnO3·0.5LiNi0.3Co0.3Mn0.4O2 Cathode by in Situ Electrochemical Quartz Crystal Microbalance.
The first-cycle behavior of layered Li-rich oxides, including Li2MnO3 activation and cathode electrolyte interphase (CEI) formation, significantly influences their electrochemical performance. However, the Li2MnO3 activation pathway and the CEI formation process are still controversial. Here, the first-cycle properties of xLi2MnO3·(1- x) LiNi0.3Co0.3Mn0.4O2 ( x = 0, 0.5, 1) cathode materials were studied with an in situ electrochemical quartz crystal microbalance (EQCM). The results demonstrate that a synergistic effect between the layered Li2MnO3 and LiNi0.3Co0.3Mn0.4O2 structures can significantly affect the activation pathway of Li1.2Ni0.12Co0.12Mn0.56O2, leading to an extra-high capacity. It is demonstrated that Li2MnO3 activation in Li-rich materials is dominated by electrochemical decomposition (oxygen redox), which is different from the activation process of pure Li2MnO3 governed by chemical decomposition (Li2O evolution). CEI evolution is closely related to Li+ extraction/insertion. The valence state variation of the metal ions (Ni, Co, Mn) in Li-rich materials can promote CEI formation. This study is of significance for understanding and designing Li-rich cathode-based batteries
Preventive effect of Ibrolipim on suppressing lipid accumulation and increasing lipoprotein lipase in the kidneys of diet-induced diabetic minipigs
<p>Abstract</p> <p>Background</p> <p>The role of renal lipoprotein lipase (LPL) <it>per se </it>in kidney diseases is still controversial and obscure. The purpose of this study was to observe the preventive effects of Ibrolipim, a LPL activator, on lipid accumulation and LPL expression in the kidneys of minipigs fed a high-sucrose and high-fat diet (HSFD).</p> <p>Methods</p> <p>Male Chinese Bama minipigs were fed a control diet or HSFD with or without 0.1 g/kg/day Ibrolipim for 5 months. Body weight, plasma glucose, insulin, lipids, LPL activity, and urinary microalbumin were measured. Renal tissue was obtained for detecting LPL activity and contents of triglyceride and cholesterol, observing the renal lipid accumulation by Oil Red O staining, and examining the mRNA and protein expression of LPL by real time PCR, Western Blot and immunohistochemistry.</p> <p>Results</p> <p>Feeding HSFD to minipigs caused weight gain, hyperglycemia, hyperinsulinemia, hyperlipidemia and microalbuminuria. HSFD increased plasma LPL activity while it decreased the mRNA and protein expression and activity of LPL in the kidney. The increases in renal triglyceride and cholesterol contents were associated with the decrease in renal LPL activity of HSFD-fed minipigs. In contrast, supplementing Ibrolipim into HSFD lowered body weight, plasma glucose, insulin, triglyceride and urinary albumin concentrations while it increased plasma total cholesterol and HDL-C. Ibrolipim suppressed the renal accumulation of triglyceride and cholesterol, and stimulated the diet-induced down-regulation of LPL expression and activity in the kidney.</p> <p>Conclusions</p> <p>Ibrolipim exerts renoprotective and hypolipidemic effects <it>via </it>the increase in renal LPL activity and expression, and thus the increased expression and activity of renal LPL play a vital role in suppressing renal lipid accumulation and ameliorating proteinuria in diet-induced diabetic minipigs.</p
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