Weyl points, as monopoles of Berry curvature in momentum space, have captured much attention recently in various branches of physics. Realizing topological materials that exhibit such nodal points is ...challenging and indeed, Weyl points have been found experimentally in transition metal arsenide and phosphide and gyroid photonic crystal whose structure is complex. If realizing even the simplest type of single Weyl nodes with a topological charge of 1 is difficult, then making a real crystal carrying higher topological charges may seem more challenging. Here we design, and fabricate using planar fabrication technology, a photonic crystal possessing single Weyl points (including type-II nodes) and multiple Weyl points with topological charges of 2 and 3. We characterize this photonic crystal and find nontrivial 2D bulk band gaps for a fixed k
and the associated surface modes. The robustness of these surface states against k
-preserving scattering is experimentally observed for the first time.
DFT calculations have been carried out to study the detailed mechanism of Rh(III)-catalyzed C–H activation/cyclization of 2-acetyl-1-arylhydrazines with alkynes leading to the formation of indoles, ...in which the hydrazine moiety is used as the internal oxidant. The energy profiles associated with the catalytic cycle, involving N–H deprotonation, C–H activation (a concerted metalation–deprotonation (CMD) process), alkyne insertion, ring rearrangement/isomerization, and finally N–N bond cleavage/reductive elimination to regenerate the active species, are presented and analyzed. Through analysis of the calculation results, we found that the combined processes of the CMD and alkyne insertion contribute to the overall rate-determining step. The N–N bond cleavage step was examined in detail to understand how the internal oxidant interacts with the metal center to facilitate the catalytic reactions. The factor influencing regioselectivity was also investigated. How different types of substrates (alkynes versus alkenes) and internal oxidants (−NH(NHAc) versus −NH(OAc)) influence the reaction mechanisms, Rh(III)/Rh(I) versus Rh(III)/Rh(V) catalytic cycles, was discussed.
Photonic analogue of topological insulator was recently predicted by arranging ε/μ (permittivity/permeability)-matched bianisotropic metamaterials into two-dimensional superlattices. However, the ...experimental observation of such photonic topological insulator is challenging as bianisotropic metamaterial is usually highly dispersive, so that the ε/μ-matching condition can only be satisfied in a narrow frequency range. Here we experimentally realize a photonic topological insulator by embedding non-bianisotropic and non-resonant metacrystal into a waveguide. The cross coupling between transverse electric and transverse magnetic modes exists in metacrystal waveguide. Using this approach, the ε/μ-matching condition is satisfied in a broad frequency range which facilitates experimental observation. The topologically non-trivial bandgap is confirmed by experimentally measured transmission spectra and calculated non-zero spin Chern numbers. Gapless spin-filtered edge states are demonstrated experimentally by measuring the magnitude and phase of the fields. The transport robustness of the edge states is also observed when an obstacle was introduced near the edge.
We demonstrate the decoration of methylamine lead bromide (MAPbBr 3 , MA: CH 3 NH 3 + ) perovskite nanoparticles on protonated graphitic carbon nitride (p-g-C 3 N 4 ) sheets to form nanocomposites ...(NCs) for the first time. The intrinsic type II band structure of MAPbBr 3 /p-g-C 3 N 4 NCs resulted in significant charge separation properties, which were greatly beneficial for related applications in photoelectric conversion. The interfacial charge transfer behavior of MAPbBr 3 /p-g-C 3 N 4 NCs was analyzed via time-resolved photoluminescence (TRPL) spectroscopy and singular-value decomposition global fitting (SVD-GF), which revealed that photoexcited electrons in the conduction band (CB) and shallow-trap (ST) states of MAPbBr 3 could be transferred into the CB of g-C 3 N 4 . The fitting results for TRPL traces indicated that the control of the related compositions could modulate the interfacial charge carrier dynamics of MAPbBr 3 /g-C 3 N 4 NCs. An increase in the charge transfer rate constant ( k et ) for MAPbBr 3 /g-C 3 N 4 NCs was discovered when the constituent ratio of p-g-C 3 N 4 was enhanced. Furthermore, we utilized MAPbBr 3 /p-g-C 3 N 4 NCs as a photocatalyst to carry out the photocatalytic reduction of p -nitrophenol (PNP) under visible-light irradiation. A significant photoreduction rate ( k PNP ) of PNP was observed in the photocatalytic reaction, which indicated the great potential of MAPbBr 3 /p-g-C 3 N 4 NCs to convert solar energy into chemical energy. In particular, the present investigation opens a new field for organolead bromide perovskites in applications in photocatalysis, as well as related photoelectric conversion.
Cosmological tensions can arise within the Lamda cold dark matter scenario amongst different observational windows, which may indicate new physics beyond the standard paradigm if confirmed by ...measurements. In this article, we report how to alleviate both the H0 and σ8 tensions simultaneously within torsional gravity from the perspective of effective field theory. Following these observations, we construct concrete models of Lagrangians of torsional gravity. Specifically, we consider the parametrization f( T ) = −T − 2Λ/M2P + αTβ, where two out of the three parameters are independent. This model can efficiently fit observations solving the two tensions. To our knowledge, this is the first time where a modified gravity theory can alleviate both H0 and σ8 tensions simultaneously, hence, offering an additional argument in favor of gravitational modification.
Abstract
The continuous nanohertz gravitational waves (GWs) from individual supermassive binary black holes (SMBBHs) can be encoded in the timing residuals of pulsar timing arrays (PTAs). For each ...pulsar, the residuals actually contain an Earth term and a pulsar term, but usually only the Earth term is considered as a signal and the pulsar term is dropped. This leads to parameter-estimation biases (PEBs) for the SMBBHs, and currently there are no convenient evaluations of the PEBs. In this article, we formulate the PEBs for a SMBBH with an eccentric orbit. In our analyses, the unknown phases of pulsar terms are treated as random variables obeying the uniform distribution
U
0, 2
π
), due to the fact that pulsar distances are generally poorly measured. Our analytical results are in accordance with the numerical work by Zhu et al. at 1.5
σ
level, which implies that our formulae are effective in estimating magnitudes of the PEBs. Additionally, we find that the biases Δ
φ
E
and Δ
e
/
e
for two parameters—that is, Earth-term phase
φ
E
and orbital eccentricity
e
—monotonically decrease as
e
increases, which partly confirms a hypothesis in our previous work. Furthermore, we also calculate the PEBs caused by the recently observed common-spectrum process (CSP). We find that if the strain amplitude of the continuous GW is significantly stronger (three times larger, in our cases) than the stochastic GW background, then the PEBs from pulsar terms are larger than those from the CSP. Our formulae of the PEBs can be conveniently applied in the future PTA data analyses.
Understanding the charge-transfer mechanism in metal-organic frameworks is of great importance to design photoactive, electroactive and conductive materials. A novel Zn
(ii)-
organic framework shows ...a 1D stair-like structure with strong π-π stacking interactions between the mixed linkers. What's more, it displays reversible photochromic properties and its thin film exhibits electroactive properties due to the redox active behavior of NDI core parts and the electron or charge transfer within the linkers. Also, TD-DFT computational calculations show that inter-ligand charge-transfer interactions exist in this novel photochromic and redox active MOF.
A novel Zn(
ii
)-organic framework with 1D stair-like structure displays reversible photochromic and redox active properties. And inter-ligands charge-transfer interactions exist in this material.
HOXA11 antisense RNA (HOXA11-AS) has been shown to be involved in tumorigenesis and development of different cancers. However, the role of HOXA11-AS in non-small cell lung cancer (NSCLC) remains ...unclear. In this study, we firstly explored and confirmed the expression of HOXA11-AS in NSCLC tissues and cells. Cytometry, CCK-8, cell scratch, migration, Matrigel invasion and flow cytometry assays were performed to determine the biological impact of HOXA11-AS in vitro. Furthermore, a chick embryo chorioallantoic membrane (CAM) model of NSCLC was constructed to explore the effect of HOXA11-AS on tumorigenicity and angiogenesis in vivo. Additionally, bioinformatics analyses were performed to investigate the prospective pathways of HOXA11-AS co-expressed genes. As results, HOXA11-AS was markedly highly expressed in NSCLC tissues and cells. Furthermore, the proliferation, migration, invasion, tumorigenic and angiogenic ability of NSCLC cells were all inhibited and apoptosis was induced after HOXA11-AS knock-down. HOXA11-AS RNAi also led to cell cycle arrest on G0/G1 or G2/M phase. In addition, the non-small cell lung cancer pathway might be involved in regulating the co-expressed genes of HOXA11-AS in NSCLC. These results indicate that HOXA11-AS plays pivotal roles in NSCLC and it can become a novel therapeutic direction for treating NSCLC.
Lung cancer ranks as the leading cause of cancer-related deaths worldwide and we performed this meta-analysis to investigate eligible studies and determine the prognostic effect of Ki-67.
In total, ...108 studies in 95 articles with 14,732 patients were found to be eligible, of which 96 studies reported on overall survival (OS) and 19 studies reported on disease-free survival (DFS) with relation to Ki-67 expression in lung cancer patients.
The pooled hazard ratio (HR) indicated that a high Ki-67 level could be a valuable prognostic factor for lung cancer (HR = 1.122 for OS, P < 0.001 and HR = 1.894 for DFS, P < 0.001). Subsequently, the results revealed that a high Ki-67 level was significantly associated with clinical parameters of lung cancer including age (odd ratio, OR = 1.246 for older patients, P = 0.018), gender (OR = 1.874 for males, P < 0.001) and smoking status (OR = 3.087 for smokers, P < 0.001). Additionally, significant positive correlations were found between Ki-67 overexpression and poorer differentiation (OR = 1.993, P = 0.003), larger tumor size (OR = 1.436, P = 0.003), and higher pathologic stages (OR = 1.867 for III-IV, P < 0.001). Furthermore, high expression of Ki-67 was found to be a valuable predictive factor for lymph node metastasis positive (OR = 1.653, P < 0.001) and advanced TNM stages (OR = 1.497 for stage III-IV, P = 0.024). Finally, no publication bias was detected in any of the analyses.
This study highlights that the high expression of Ki-67 is clinically relevant in terms of the prognostic and clinicopathological characteristics for lung cancer. Nevertheless, more prospective well-designed studies are warranted to validate these findings.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Nodal lines are degeneracies formed by crossing bands in three-dimensional momentum space. Interestingly, these degenerate lines can chain together via touching points and manifest as nodal chains. ...These nodal chains are usually embedded in two orthogonal planes and protected by the corresponding mirror symmetries. Here, we propose and demonstrate an in-plane nodal chain in photonics, where all chained nodal lines coexist in a single mirror plane instead of two orthogonal ones. The chain point is stabilized by the intrinsic symmetry that is specific to electromagnetic waves at the Г point of zero frequency. By adding another mirror plane, we find a nodal ring that is constructed by two higher bands and links with the in-plane nodal chain. The nodal link in momentum space exhibits non-Abelian characteristics on a C
T - invariant plane, where admissible transitions of the nodal link structure are determined by generalized quaternion charges. Through near-field scanning measurements of bi-anisotropic metamaterials, we experimentally mapped out the in-plane nodal chain and nodal link in such systems.
PDF
