601 research outputs found
Modulation of chiral anomaly and bilinear magnetoconductivity in Weyl semimetals by impurity-resonance states
The phenomenon of nonlinear transport has attracted tremendous interest
within the condensed matter community. We present a theoretical framework for
nonlinear transport based on the nonequilibrium retarded Green's function, and
examine the impact of disorder on nonlinear magnetotransport in Weyl semimetals
(WSMs). It is demonstrated that bilinear magnetoconductivity can be induced in
disordered WSMs by several mechanisms, including impurity-induced tilting of
the Weyl cones, Lorentz-force-induced normal orbital magnetic moment, and
chiral anomaly arising from the Berry-curvature-induced anomalous orbital
magnetic moment. Additionally, we observe that the localization of Weyl
fermions by impurity scattering will lead to resonant dips in both the chiral
chemical potential and magnetoconductivity when the Fermi energy approaches the
impurity resonance states. Our findings offer a theoretical proposition for
modulating nonreciprocal transport in topological semimetals.Comment: 5 figure
Acute and acute-on-chronic kidney injury of patients with decompensated heart failure: impact on outcomes
BACKGROUND: Acute worsening of renal function, an independent risk factor for adverse outcomes in acute decompensated heart failure (ADHF), occurs as a consequence of new onset kidney injury (AKI) or acute deterioration of pre-existed chronic kidney disease (CKD) (acute-on-chronic kidney injury, ACKI). However, the possible difference in prognostic implication between AKI and ACKI has not been well established. METHODS: We studied all consecutive patients hospitalized with ADHF from 2003 through 2010 in Nanfang Hospital. We classified patients as with or without pre-existed CKD based on the mean estimated glomerular filtration rate (eGFR) over a six-month period before hospitalization. AKI and ACKI were defined by RIFLE criteria according to the increase of the index serum creatinine. RESULTS: A total of 1,005 patients were enrolled. The incidence of ACKI was higher than that of AKI. The proportion of patients with diuretic resistance was higher among patients with pre-existed CKD than among those without CKD (16.9% vs. 9.9%, P = 0.002). Compared with AKI, ACKI was associated with higher risk for in-hospital mortality, long hospital stay, and failure in renal function recovery. Pre-existed CKD and development of acute worsening of renal function during hospitalization were the independent risk factors for in-hospital death after adjustment by the other risk factors. The RIFLE classification predicted all-cause and cardiac mortality in both AKI and ACKI. CONCLUSIONS: Patients with ACKI were at greatest risk of adverse short-term outcomes in ADHF. Monitoring eGFR and identifying CKD should not be ignored in patients with cardiovascular disease
Dibromidobis{1-[4-(pyridin-4-yl)phenyl]ethanone-κN}mercury(II)
In the title compound, [HgBr2(C13H11NO)2], the HgII atom adopts a four-coordinated HgN2Br2 geometry, formed by two pyridine N atoms from two ligands and two bromide anions. The complex is located on a twofold axis. The coordination geometry is close to forming a see-saw (SS-4) polyhedron, the symmetry-related organic ligands being almost perpendicular; the dihedral angles between the two pyridine rings and between the two benzene rings are 85.5 (4) and 87.7 (4)°, respectively. Within the organic ligand, the pyridine ring is nearly coplanar with the benzene ring [dihedral angle = 13.1 (8)°]. In the crystal, the molecular complexes are connected through weak intermolecular C—H⋯Br contacts
Graphene oxide nanoparticles for enhanced photothermal cancer cell therapy under the irradiation of a femtosecond laser beam
Nano-sized graphene and graphene oxide (GO) are promising for biomedical applications, such as drug delivery and photothermal therapy of cancer. It is observed in thiswork that the ultrafast reduction of GO nanoparticles (GONs)with a femtosecond laser beam creates extensive microbubbling. To understand the surface chemistry of GONs on the microbubble formation, the GONs were reduced to remove
most of the oxygen-containing groups to get reduced GONs
(rGONs). Microbubbling was not observed when the rGONs
were irradiated by the laser. The instant collapse of the
microbubbles may produce microcavitation effect that brings
about localized mechanical damage. To understand the
potential applications of this phenomenon, cancer cells
labeled with GONs or rGONs were irradiated with the laser.
Interestingly, the microbubbling effect greatly facilitated the
destruction of cancer cells. When microbubbles were produced,
the effective laser power was reduced to less than
half of what is needed when microbubbling is absent. This
finding will contribute to the safe application of femtosecond
laser in the medical area by taking advantage of the ultrafast
reduction of GONs. It may also find other important applications
that need highly localized microcavitation effects
High-Brightness and Color-Tunable FAPbBr(3) Perovskite Nanocrystals 2.0 Enable Ultrapure Green Luminescence for Achieving Recommendation 2020 Displays
To best catch human eyes in next-generation displays, the updated recommendation 2020 (Rec. 2020) standard has called for ultrapure green emitters to be qualified with a narrow emission of 525-535 nm with a full width at half-maximum (fwhm) below 25 nm. However, it is still challenging to find an emitter which can simultaneously cover these two criteria. Instead of traditional II-VI group semiconductor quantum dots, perovskite nanocrystals (NCs) can render versatile emitting tunability to allow them access to the Rec. 2020 standard. Herein, to realize the critical window of Rec. 2020, we have proposed a scalable, room temperature synthesis route of formamidinium lead bromide (FAPbBr3) NCs using a sole ligand of sulfobetaine-18 (SBE-18). The as-synthesized FAPbBr3 NCs exhibit an ideal emission at 534 nm with an ultranarrow fwhm of 20.5 nm and a high photoluminescence quantum yield of 90.6%, overwhelming the FAPbBr3 nanoplates capped with oleic acid/oleylamine (OA/OAM). Introducing these high quality NCs into backlight displays, an ultrapure green backlight which covers ≈85.7% of the Rec. 2020 standard in the CIE 1931 color space is achieved, signifying the "greenest" backlight till now. Thus, we can foresee perovskite NCs as the most potential candidates for next-generation displays
RKKY signals characterizing the topological phase transitions in Floquet Dirac semimetals
Recently, the Floquet -type material has been proposed as an
ideal platform for realizing various phases, i.e., the spin-degenerate Dirac
semimetal (DSM) can be turned into the Weyl semimetal (WSM), and even to the
Weyl half-metal (WHM). Instead of the conventional electrical methods, we use
the RKKY interaction to characterize the topological phase transitions in this
paper. It is found that detecting the Ising term is feasible for
distinguishing the phase transition of DSM/WSM, since the emergence of is
induced by the broken spin degeneracy. For the case with impurities deposited
on axis (the line connecting the Weyl points), the Heisenberg term
coexists with in the WSM, while is filtered out and only
survives in the WHM. This magnetic filtering effect is a reflection of the
fully spin-polarized property (one spin band is in the WSM phase while the
other is gapped) of the WHM, and it can act a signal to capture the phase
transition of WSM/WHM. This signal can not be disturbed unless the direction of
the impurities greatly deviates from axis. Interestingly, as the impurities
are moved into the - plane, there arises another signal (a dip structure
for at the phase boundary), which can also identify the phase transition
of WSM/WHM. Furthermore, we have verified that all magnetic signals are robust
to the term that breaks the electron-hole symmetry. Besides characterizing the
phase transitions, our results also suggest that the Floquet DSMs are power
platforms for controlling the magnetic interaction.Comment: 15 pages, 10 figure
Local nearly non-strained perovskite lattice approaching a broad environmental stability window of efficient solar cells
Twist and fracture of surface lattice tend to occur under harsh condition due to the soft lattice natures of hybrid perovskite materials. Accordingly, surface defects and lattice distortion are produced, which allow the performance loss and notorious degradation in perovskite solar cells (PSCs). In our work, judiciously selected conjugated ligand was employed as the film intermediary, from which rigid and delocalization 4-phenylpyridine (4-pPy) exhibited the most significant improvement on both optoelectrical performance and stability of PSCs. By regulating the film crystallization kinetics, high-quality perovskite films can be obtained with preferable crystal orientation. Moreover, benefiting from the defects passivation and unidirectional bonding effect, coordinated 4-pPy “scaffold” on the lattice surface could mitigate vacancy formation and lattice twist/fracture under severe conditions. The resulted p-i-n planar device shows a considerable PCE of 21.12% (certified 20.2%) with negligible hysteresis, as well as an excellent storage (90% of original PCE after 1000 h at 60% RH), operating (90% of original PCE after 600 h at maximum power point) and thermal stress (89% of original PCE after 500 h at 85 °C) stability. It is hoped that our findings could open a new way to accelerate continued progress on PSCs regimes for efficieny maximization and stability prolongation
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