Graphene-based materials have generated tremendous interest in a wide range of research activities. A wide variety of graphene related materials have been synthesised for potential applications in ...electronics, energy storage, catalysis, and gas sorption, storage, separation and sensing. Recently, gas sorption, storage and separation in porous nanocarbons and metal-organic frameworks have received increasing attention. In particular, the tuneable porosity, surface area and functionality of the lightweight and stable graphene-based materials open up great scope for those applications. Such structural features can be achieved by the design and control of the synthesis routes. Here, we highlight recent progresses and challenges in the syntheses of graphene-based materials with hierarchical pore structures, tuneable high surface area, chemical doping and surface functionalization for gas (H2, CH4, CO2, N2, NH3, NO2, H2S, SO2, etc.) sorption, storage and separation.
We bound the greatest common divisor of two coprime multivariable polynomials evaluated at algebraic numbers, generalizing work of Levin, and going towards conjectured inequalities of Silverman and ...Vojta. As an application, we prove results on greatest common divisors of terms from two linear recurrence sequences, extending the results of Levin, who considered the case where the linear recurrences are simple, and improving recent results of Grieve and Wang. The proofs rely on Schmidt’s Subspace Theorem.
A large number of SARS-related coronaviruses (SARSr-CoV) have been detected in horseshoe bats since 2005 in different areas of China. However, these bat SARSr-CoVs show sequence differences from SARS ...coronavirus (SARS-CoV) in different genes (S, ORF8, ORF3, etc) and are considered unlikely to represent the direct progenitor of SARS-CoV. Herein, we report the findings of our 5-year surveillance of SARSr-CoVs in a cave inhabited by multiple species of horseshoe bats in Yunnan Province, China. The full-length genomes of 11 newly discovered SARSr-CoV strains, together with our previous findings, reveals that the SARSr-CoVs circulating in this single location are highly diverse in the S gene, ORF3 and ORF8. Importantly, strains with high genetic similarity to SARS-CoV in the hypervariable N-terminal domain (NTD) and receptor-binding domain (RBD) of the S1 gene, the ORF3 and ORF8 region, respectively, were all discovered in this cave. In addition, we report the first discovery of bat SARSr-CoVs highly similar to human SARS-CoV in ORF3b and in the split ORF8a and 8b. Moreover, SARSr-CoV strains from this cave were more closely related to SARS-CoV in the non-structural protein genes ORF1a and 1b compared with those detected elsewhere. Recombination analysis shows evidence of frequent recombination events within the S gene and around the ORF8 between these SARSr-CoVs. We hypothesize that the direct progenitor of SARS-CoV may have originated after sequential recombination events between the precursors of these SARSr-CoVs. Cell entry studies demonstrated that three newly identified SARSr-CoVs with different S protein sequences are all able to use human ACE2 as the receptor, further exhibiting the close relationship between strains in this cave and SARS-CoV. This work provides new insights into the origin and evolution of SARS-CoV and highlights the necessity of preparedness for future emergence of SARS-like diseases.
Long non‐coding RNAs (LncRNAs) have been recently found to be pervasively transcribed in the genome and critical regulators of the epigenome. HOTAIR, as a well‐known LncRNA, has been found to play ...important roles in several tumors. Herein, the clinical application value and biological functions of HOTAIR were focused and explored in esophageal squamous cell carcinoma (ESCC). It was found that there was a great upregulation of HOTAIR in ESCC compared to their adjacent normal esophageal tissues. Meanwhile, patients with high HOTAIR expression have a significantly poorer prognosis than those with low expression. Moreover, HOTAIR was further validated to promote migration and invasion of ESCC cells in vitro. Then some specific molecules with great significance were investigated after HOTAIR overexpression using microarray and quantitative real time‐polymerase chain reaction (qPCR). WIF‐1 playing an important role in Wnt/β‐catenin signaling pathway was selected and further tested by immunehistochemistry. Generally, inverse correlation between HOTAIR and WIF‐1 expression was demonstrated both in ESCC cells and tissues. Mechanistically, HOTAIR directly decreased WIF‐1 expression by promoting its histone H3K27 methylation in the promoter region and then activated the Wnt/β‐catenin signaling pathway. This newly identified HOTAIR/WIF‐1 axis clarified the molecular mechanism of ESCC cell metastasis and represented a novel therapeutic target in patients with ESCC.
HOTAIR, a long non coding RNA, has been linked to the progression of several types of human cancer. In this study, we found that HOTAIR was not only significantly up‐regulated in tumor tissues, but also significantly associated with poor clinical outcome in patients with esophageal squamous cell carcinoma (ESCC). ESCC cells with HOTAIR overexpression displayed aberrant activated WNT signaling pathway by inhibiting the expression of WNT‐inhibitor factor 1, thereby promote the migration and invasion of ESCC cells. On the contrary, silencing of HOTAIR in ESCC cells led to decreased migration and invasion ability. Together, these results suggest that HOTAIR overexpression may serve as a novel prognostic biomarker and potential therapeutic target for the treatment of human ESCC.
Since the outbreak of severe acute respiratory syndrome (SARS) 18 years ago, a large number of SARS-related coronaviruses (SARSr-CoVs) have been discovered in their natural reservoir host, bats
. ...Previous studies have shown that some bat SARSr-CoVs have the potential to infect humans
. Here we report the identification and characterization of a new coronavirus (2019-nCoV), which caused an epidemic of acute respiratory syndrome in humans in Wuhan, China. The epidemic, which started on 12 December 2019, had caused 2,794 laboratory-confirmed infections including 80 deaths by 26 January 2020. Full-length genome sequences were obtained from five patients at an early stage of the outbreak. The sequences are almost identical and share 79.6% sequence identity to SARS-CoV. Furthermore, we show that 2019-nCoV is 96% identical at the whole-genome level to a bat coronavirus. Pairwise protein sequence analysis of seven conserved non-structural proteins domains show that this virus belongs to the species of SARSr-CoV. In addition, 2019-nCoV virus isolated from the bronchoalveolar lavage fluid of a critically ill patient could be neutralized by sera from several patients. Notably, we confirmed that 2019-nCoV uses the same cell entry receptor-angiotensin converting enzyme II (ACE2)-as SARS-CoV.
A highly effective and facile synthesis route is developed to create and tailor metal‐decorated and nitrogen‐functionalized active microporous carbon materials from ZIF‐8. Clear metal‐ and ...pyrrolic‐N‐induced enhancements of the cyclic CO2 uptake capacities and binding energies are achieved, particularly at a much lower carbonization temperature of 700 °C than those often reported (1000 °C). The high‐temperature carbonization can enhance the porosity but only at the expense of considerable losses of sample yield and metal and N functional sites. The findings are comparatively discussed with carbons derived from metal–organic frameworks (MOFs) reported previously. Furthermore, the porosity of the MOF‐derived carbon is critically dependent on the structure of the precursor MOF and the crystal growth. The current strategy offers a new and effective route for the creation and tuning of highly active and functionalized carbon structures in high yields and with low energy consumption.
Carbon control: A detailed structural analysis is performed for MOF‐derived nanoporous carbons, using ZIF‐8 as a case study as one of the most commonly used precursors. The controlled carbonization of ZIF‐8 yields very different porous carbons with variation of the activated C and N sites. The sample prepared at around 700 °C shows a high content of highly active N functional groups. The samples have enhanced CO2 uptake, binding, and selectivity due to the N and Zn sites.
Competing inhomogeneous orders are a central feature of correlated electron materials, including the high-temperature superconductors. The two-dimensional Hubbard model serves as the canonical ...microscopic physical model for such systems. Multiple orders have been proposed in the underdoped part of the phase diagram, which corresponds to a regime of maximum numerical difficulty. By combining the latest numerical methods in exhaustive simulations, we uncover the ordering in the underdoped ground state. We find a stripe order that has a highly compressible wavelength on an energy scale of a few kelvin, with wavelength fluctuations coupled to pairing order. The favored filled stripe order is different from that seen in real materials. Our results demonstrate the power of modern numerical methods to solve microscopic models, even in challenging settings.
Abstract
The braking index is of great importance for interpreting the spin-down mechanism of pulsar rotation. The sudden spin-down rate transition of PSR B0540−69, the lowest braking index
n
= ...0.031, and its variations up to 1.2 in its later phases, without glitches or changes in X-ray pulsed flux or shape, are the most enigmatic problem that challenges our understanding of the correlation between pulsar spin-down and magnetospheric emission. Here we discuss the above issue on the external and internal grounds of pulsar dynamics. It is found that the increase of the open field line region of the pulsar magnetosphere would give a plausible explanation for the state transition and the braking index of 0.031 of PSR B0540−69, and changes in the moment of inertia of PSR B0540−69 after the state transition may account for the variable braking indices in its subsequent phases. Results indicate that, on the one hand, a change in the magnetosphere size of a pulsar would influence the external braking torque and have a substantial impact on the observed braking index; and, on the other hand, a sudden change in external torque may trigger the mechanism that could slowly increase the moment of inertia of the pulsar and cause an observable effect on the spin frequency second derivatives. This is hardly explained under the regular glitch hypothesis. In this respect, PSR B0540−69 would be the ideal candidate to study the inside and outside dynamics of a pulsar.
In this article, we consider the distributed fault-tolerant resilient consensus problem for heterogeneous multiagent systems (MASs) under both physical failures and network denial-of-service (DoS) ...attacks. Different from the existing consensus results, the dynamic model of the leader is unknown for all followers in this article. To learn this unknown dynamic model under the influence of DoS attacks, a distributed resilient learning algorithm is proposed by using the idea of data-driven. Based on the learned dynamic model of the leader, a distributed resilient estimator is designed for each agent to estimate the states of the leader. Then, a new adaptive fault-tolerant resilient controller is designed to resist the effect of physical failures and network DoS attacks. Moreover, it is shown that the consensus can be achieved with the proposed learning-based fault-tolerant resilient control method. Finally, a simulation example is provided to show the effectiveness of the proposed method.
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