We identify the quantum metric dipole as the geometric origin of the nonreciprocal directional dichroism which describes the change in the refractive index upon reversing the light propagation ...direction. Specifically, we find that the static limit of the nonreciprocal directional dichroism corresponds to a quadrupolar transport current from the quantum metric dipole, in response to a quadrupolar electric field. Moreover, at a finite frequency, we demonstrate that the steepest slope of the averaged quantum metric dipole gives rise to a peak in the differential refractive index between counterpropagating lights. Finally, we illustrate both features in a low-energy model.
The emergence of two-dimensional Dirac materials, particularly transition metal dichalcogenides (TMDs), has reinvigorated interest in valleytronics, which utilizes the electronic valley degree of ...freedom for information storage and processing. Here, we review the basic valley-dependent properties and their experimental demonstrations in single-layer semiconductor TMDs with an emphasis on the effects of band topology and light–valley interactions. We also provide a brief summary of the recent advances on controlling the valley degree of freedom in TMDs with light and other means for potential applications.
In a collinear antiferromagnet with easy-axis anisotropy, symmetry guarantees that the spin wave modes are doubly degenerate. The two modes carry opposite spin angular momentum and exhibit opposite ...chirality. Using a honeycomb antiferromagnet in the presence of the Dzyaloshinskii-Moriya interaction, we show that a longitudinal temperature gradient can drive the two modes to opposite transverse directions, realizing a spin Nernst effect of magnons with vanishing thermal Hall current. We find that magnons around the Γ point and the K point contribute oppositely to the transverse spin transport, and their competition leads to a sign change of the spin Nernst coefficient at finite temperature. Possible material candidates are discussed.
The sigma (σ)‐hole effect has emerged as a promising tool to construct novel architectures endowed with new properties. A simple yet effective strategy for the generation of monofluoromethyl radicals ...is a continuing challenge within the synthetic community. Fluoromethylphosphonium salts are easily available, air‐ and thermally stable, as well as simple‐to‐handle. Herein, we report the ability of the σ‐hole effect to facilitate the visible‐light‐triggered photolysis of phosphonium iodide salts, a charge‐transfer complex, selectively giving fluoromethyl radicals. The usefulness and versatility of this new protocol are demonstrated through the mono‐, di‐, and trifluoromethylation of a variety of alkenes.
Simple and selective synthesis of fluoromethylated alkenes, heterocycles, enamines and heteroarenes by using the readily available and bench‐stable fluoromethylphosphonium iodide salts is described. Key to this privileged transformation is the formation of a photoactive charge‐transfer complex involving the σ‐hole effect of phosphonium salts.
Long intergenic noncoding RNA 460 (LINC00460) has been identified as a critical regulator for multiple types of cancers. However, the biological role and underlying mechanism in human papillary ...thyroid carcinoma (PTC) still remain unclear and need to be uncovered. This study was aimed to ascertain the biological role and molecular mechanism of LINC00460 in PTC progression. Our findings revealed that the level of LINC00460 was significantly upregulated in PTC tissues and cell lines, which was positively correlated with advanced tumor–node–metastasis (TNM) stage and lymph node metastasis. Cellular experiments exhibited that knockdown of LINC00460 decreased proliferative, migratory, and invasive abilities of PTC cells. Mechanism assays noted that knockdown of LINC00460 suppressed cell proliferation, migration, and invasion, and inhibited expression of sphingosine kinase 2 (SphK2, a target of miR‐613) in PTC cells, at least in part, by regulating miR‐613. These findings suggested that LINC00460 could function as a competing endogenous RNA to regulate SphK2 expression by sponging miR‐613 in PTC. Targeting LINC00460 could be a promising therapeutic strategy for patients with PTC.
The present study first demonstrated that the expression of long intergenic noncoding RNA 460 (LINC00460) was upregulated in papillary thyroid carcinoma (PTC) tissues and cell lines. And the elevation of LINC00460 was correlated with advanced tumor–node–metastasis (TNM) stage and lymph node metastasis. Our results also revealed that the oncogene LINC00460 promoted PTC progression via partly regulating miR‐613/sphingosine kinase 2 (SphK2) axis. These findings suggested that the LINC00460/miR‐613/SphK2 might act as a novel therapeutic target for the treatment of PTC.
Purpose To compare the benefits and harms of radiofrequency ablation (RFA) and hepatic resection (HR) and to test the consistency of currently available evidence. Materials and Methods PubMed, ...Embase, and the Cochrane Library were systematically searched for randomized controlled trials (RCTs) that compared the effects of HR and RFA for Barcelona Clinic Liver Cancer very early or early stage hepatocellular carcinoma (HCC). The primary outcome was overall survival, and secondary outcomes were recurrence rate, complication rate, and hospitalization duration. A random- or fixed-effects model according to the level of heterogeneity was applied. The meta-analysis was performed by using software, and trial sequential analysis (TSA) was performed. Results Five trials examining 742 patients were included in this study (sizes of trials: 161, 230, 168, 120, and 63 patients). The meta-analysis showed that RFA and HR had similar overall survival at 1 year (relative risk RR, 1.39; 95% confidence interval CI: 0.36, 5.33; P = .63) and 3 years (RR, 1.40; 95% CI: 0.75, 2.62; P = .29), whereas RFA resulted in decreased overall survival compared with HR at 5 years (RR: 1.91; 95% CI: 1.32, 2.79; P = .001). The TSA showed that more trials were needed to control random errors. The incidence of overall recurrence was markedly higher and the hospitalization duration was significantly shorter in the RFA group than in the HR group, which was confirmed by TSA. Complications may have been less frequent in the RFA group, but TSA showed that additional trials were necessary to confirm this conclusion. Conclusion The indication for RFA as a primary treatment for patients who are eligible for HR with early stage HCC is unclear, and additional well-designed RCTs are needed.
RSNA, 2017 Online supplemental material is available for this article.
Detecting the orientation of the Néel vector is a major research topic in antiferromagnetic spintronics. Here we recognize the intrinsic nonlinear Hall effect, which is independent of the relaxation ...time, as a prominent contribution to the time-reversal-odd second order conductivity and can be used to detect the reversal of the Néel vector. In contrast, the Berry-curvature-dipole-induced nonlinear Hall effect depends linearly on relaxation time and is time-reversal even. We study the intrinsic nonlinear Hall effect in an antiferromagnetic metal: tetragonal CuMnAs, and show that its nonlinear Hall conductivity can reach the order of mA/V^{2}. The dependence on the chemical potential of such nonlinear Hall conductivity can be qualitatively explained by a tilted massive Dirac model. Moreover, we demonstrate its strong temperature dependence and briefly discuss its competition with the second order Drude conductivity. Finally, a complete survey of magnetic point groups is presented, providing guidelines for finding more antiferromagnetic materials with the intrinsic nonlinear Hall effect.
We propose a new mechanism for the thermal Hall effect in exchange spin-wave systems, which is induced by the magnon-phonon interaction. Using symmetry arguments, we first show that this effect is ...quite general, and exists whenever the mirror symmetry in the direction of the magnetization is broken. We then demonstrate our result in a collinear ferromagnet on a square lattice, with perpendicular easy-axis anisotropy and Dzyaloshinskii-Moriya interaction from mirror symmetry breaking. We show that the thermal Hall conductivity is controlled by the resonant contribution from the anticrossing points between the magnon and phonon branches, and estimate its size to be comparable to that of the magnon-mediated thermal Hall effect.
This article summarizes the likely benefits of melatonin in the attenuation of COVID-19 based on its putative pathogenesis. The recent outbreak of COVID-19 has become a pandemic with tens of ...thousands of infected patients. Based on clinical features, pathology, the pathogenesis of acute respiratory disorder induced by either highly homogenous coronaviruses or other pathogens, the evidence suggests that excessive inflammation, oxidation, and an exaggerated immune response very likely contribute to COVID-19 pathology. This leads to a cytokine storm and subsequent progression to acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) and often death. Melatonin, a well-known anti-inflammatory and anti-oxidative molecule, is protective against ALI/ARDS caused by viral and other pathogens. Melatonin is effective in critical care patients by reducing vessel permeability, anxiety, sedation use, and improving sleeping quality, which might also be beneficial for better clinical outcomes for COVID-19 patients. Notably, melatonin has a high safety profile. There is significant data showing that melatonin limits virus-related diseases and would also likely be beneficial in COVID-19 patients. Additional experiments and clinical studies are required to confirm this speculation.
Melatonin as a potential adjuvant treatment for COVID-19. Display omitted
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