Knowledge graph (KG) embedding is to embed components of a KG including entities and relations into continuous vector spaces, so as to simplify the manipulation while preserving the inherent ...structure of the KG. It can benefit a variety of downstream tasks such as KG completion and relation extraction, and hence has quickly gained massive attention. In this article, we provide a systematic review of existing techniques, including not only the state-of-the-arts but also those with latest trends. Particularly, we make the review based on the type of information used in the embedding task. Techniques that conduct embedding using only facts observed in the KG are first introduced. We describe the overall framework, specific model design, typical training procedures, as well as pros and cons of such techniques. After that, we discuss techniques that further incorporate additional information besides facts. We focus specifically on the use of entity types, relation paths, textual descriptions, and logical rules. Finally, we briefly introduce how KG embedding can be applied to and benefit a wide variety of downstream tasks such as KG completion, relation extraction, question answering, and so forth.
A Au55 nanocluster with the composition of Au55(p‐MBT)24(Ph3P)6(SbF6)3 (p‐MBT=4‐methylbenzenethiolate) is synthesized via direct reduction of gold‐phosphine and gold‐thiolate precursors. ...Single‐crystal X‐ray diffraction reveals that this Au55 nanocluster features a face‐centered cubic (fcc) Au55 kernel, different from the well‐known two‐shell cuboctahedral arrangement in Au55(Ph3P)12Cl6. The Au55 cluster shows a wide optical absorption band with optical energy gap (Eg=1.28 eV). It is found that the exclusion of chloride is crucial for the formation of the title cluster, otherwise rod‐like Au25(SR)5(PPh3)10Cl22+ is obtained. The strategy to run synthetic reaction in the absence of halide leads to new members of phosphine/thiolate co‐protected metal nanoclusters. The Au55 nanocluster exhibits high catalytic activity and selectivity for electrochemical reduction of CO2 to CO; the Faradaic efficiency (FE) reaches 94.1 % at −0.6 V vs. reversible hydrogen electrode (RHE).
The gold nanocluster Au55(p‐MBT)24(Ph3P)6(SbF6)3 (p‐MBT=4‐methylbenzenethiolate) features a face‐centered cubic Au55 kernel. This cluster exhibits high catalytic activity and selectivity for electrochemical reduction of CO2 to CO, and the Faradaic efficiency (FE) reaches 94.1 % at −0.6 V. The exclusion of chloride is an effective strategy to generate new members of ligand‐protected metal nanoclusters.
Paeonia decomposita, endemic to China, has important ornamental, medicinal, and economic value and is regarded as an endangered plant. The genetic diversity and population structure have seldom been ...described. A conservation management plan is not currently available.
In the present study, 16 pairs of simple sequence repeat (SSR) primers were used to evaluate the genetic diversity and population structure. A total of 122 alleles were obtained with a mean of 7.625 alleles per locus. The expected heterozygosity (H
) varied from 0.043 to 0.901 (mean 0.492) in 16 primers. Moderate genetic diversity (H
= 0.405) among populations was revealed, with Danba identified as the center of genetic diversity. Mantel tests revealed a positive correlation between geographic and genetic distance among populations (r = 0.592, P = 0.0001), demonstrating consistency with the isolation by distance model. Analysis of molecular variance (AMOVA) indicated that the principal molecular variance existed within populations (73.48%) rather than among populations (26.52%). Bayesian structure analysis and principal coordinate analysis (PCoA) supported the classification of the populations into three clusters.
This is the first study of the genetic diversity and population structure of P. decomposita using SSR. Three management units were proposed as conservation measures. The results will be beneficial for the conservation and exploitation of the species, providing a theoretical basis for further research of its evolution and phylogeography.
Atomically precise gold nanoclusters provide great opportunities to explore the relationship between the structure and properties of nanogold catalysts. A nanocluster consists of a metal core and a ...surface ligand shell, and both the core and shell have significant effects on the catalytic properties. Thanks to their precise structures, the active metal site of the clusters can be readily identified and the effects of ligands on catalysis can be disclosed. In this Minireview, we summarize recent advances in catalytic research of gold nanoclusters, emphasizing four strategies for constructing open metal sites, including by post‐treatment, the bulky ligands strategy, the surface geometric mismatch method, and heteroatom doping procedures. We also discuss the effects of ligands on the catalytic activity, selectivity, and stability of gold cluster catalysts. Finally, we present future challenges relating to gold cluster catalysis.
Structurally well‐defined gold nanoclusters are promising catalysts, and their molecular nature facilitates the design and controlled synthesis of cluster catalysts. This Minireview summarizes the strategies for constructing active sites and the effects of the ligands on cluster catalysis. The challenges and key future issues regarding catalytic applications of gold nanoclusters are discussed.
The global pandemic of COVID-19 is colliding with the epidemic of opioid use disorders (OUD) and other substance use disorders (SUD) in the United States (US). Currently, there is limited data on ...risks, disparity, and outcomes for COVID-19 in individuals suffering from SUD. This is a retrospective case-control study of electronic health records (EHRs) data of 73,099,850 unique patients, of whom 12,030 had a diagnosis of COVID-19. Patients with a recent diagnosis of SUD (within past year) were at significantly increased risk for COVID-19 (adjusted odds ratio or AOR = 8.699 8.411-8.997, P < 10
), an effect that was strongest for individuals with OUD (AOR = 10.244 9.107-11.524, P < 10
), followed by individuals with tobacco use disorder (TUD) (AOR = 8.222 (7.925-8.530, P < 10
). Compared to patients without SUD, patients with SUD had significantly higher prevalence of chronic kidney, liver, lung diseases, cardiovascular diseases, type 2 diabetes, obesity and cancer. Among patients with recent diagnosis of SUD, African Americans had significantly higher risk of COVID-19 than Caucasians (AOR = 2.173 2.01-2.349, P < 10
), with strongest effect for OUD (AOR = 4.162 3.13-5.533, P < 10
). COVID-19 patients with SUD had significantly worse outcomes (death: 9.6%, hospitalization: 41.0%) than general COVID-19 patients (death: 6.6%, hospitalization: 30.1%) and African Americans with COVID-19 and SUD had worse outcomes (death: 13.0%, hospitalization: 50.7%) than Caucasians (death: 8.6%, hospitalization: 35.2%). These findings identify individuals with SUD, especially individuals with OUD and African Americans, as having increased risk for COVID-19 and its adverse outcomes, highlighting the need to screen and treat individuals with SUD as part of the strategy to control the pandemic while ensuring no disparities in access to healthcare support.
The transportation of helium atoms in a single-walled carbon nanotube is reported via molecular dynamics simulations. The efficiency of the atomic transportation is found to be dependent on the type ...of the applied loading and the loading rate as well as the temperature in the process. Simulations show the transportation is a result of the van der Waals force between the nanotube and the helium atoms through a kink propagation initiated in the nanotube.
Advances demonstrate that the incorporation of phosphorous into the network of nitrogen, sulfur, or fluorine‐doped carbon materials can remarkably enhance their oxygen and hydrogen evolution ...activities. However, the electrocatalytic behaviors of pristine phosphorous single‐doped carbon catalysts toward the oxygen and hydrogen evolution reactions (OER and HER) are rarely investigated and their corresponding active species are not yet explored. To clearly ascertain the effects of phosphorous doping on the OER and HER and identify the active sites, herein, phosphorous unitary‐doped graphite layers with different phosphorous species distributions are prepared and the correlations between the oxygen or hydrogen evolution activity and different phosphorous species are investigated, respectively. Results indicate that phosphorous single‐doped graphite layers show a superior oxygen evolution activity to most of the reported OER catalysts and the commercial IrO2 in alkaline medium, and comparable hydrogen evolution activity to most reported carbon catalysts in acidic medium. Moreover, the relevancies unveil that the COP species are the main OER active species, and the defects derived from the decomposition of C3P = O species are the main active sites for HER, as evidenced by density functional theory calculations, showing a new perspective for the design of more effective phosphorous‐containing water‐splitting catalysts.
Electrochemical tests demonstrate that the as‐prepared phosphorous single‐doped graphite layers exhibit outstanding oxygen and hydrogen evolution activities independently. Experiments and density functional theory calculations reveal that the COP groups are the active species for the high oxygen evolution activity, and the defects derived from the decomposition of C3P = O species are the active sites for the hydrogen evolution reaction.
What are the relationships among environmental performance, green finance, and green innovation in developing countries? Existing literatures support the impact of green finance or green innovation ...on environmental performance, but rare studies query the cointegration among such three variables. We thus utilize the yearly data of 57 developing countries from 2002 to 2016 to empirically examines the relationships among environmental performance, green finance, and green innovation, via panel covariate-augmented Dickey-Fuller unit root test and the Westerlund and Edgerton (2007) cointegration test. Overall, this study confirms the existence of cointegration relationships among these variables. Moreover, the results of pooled mean group estimation suggest that environmental performance can positively affect the green innovation in the long term in the non-emerging countries and countries with better green innovation or environmental performance. Furthermore, green finance positively affects green innovation in the emerging countries and countries with lower level of green finance, while green finance negatively affects green innovation in the countries with better green innovation or environmental performance. Our empirical findings offer important policy implications for the sample of developing countries to promote green innovation and improve environmental performance.
•Check long-run relationships among environmental performance, green finance and green innovation.•Investigating the long-run and short-run impacts.•The relationship varies among different countries.
This paper reviews the application of molecular dynamics simulations on mechanical and tribological properties of polymer composites reinforced by carbon nanotubes and graphene sheet as ...reinforcements. A variety of simulation studies on modelling, calculation and analysis on enhanced elastic, tensile, fracture properties of carbon nanotubes and graphene sheet/polymer composites are introduced and reviewed. The capabilities of molecular dynamics simulations on exploring inherent mechanisms on improved tribological properties of carbon nanotubes and graphene sheet/polymer composites from atomic views are particularly discussed. Different methods of surface modifications of the two nano reinforcements on further enhancing the strength of polymer composites are summarized. Summary and recommendations for potential researches are also provided. This review is intended to provide a state-of-the-art and better understanding on applications of carbon nanotubes and graphene sheet for enhancing mechanical and tribological properties of polymer composites by molecular dynamics simulations, and inspire future efforts in this area.
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Gold nanoclusters with surface open sites are crucial for practical applications in catalysis. We have developed a surface geometric mismatch strategy by using mixed ligands of different type of ...hindrance. When bulky phosphine Ph3P and planar dipyridyl amine (Hdpa) are simultaneously used, steric repulsion between the ligands will reduce the ligand coverage of gold clusters. A well‐defined access granted gold nanocluster Au23(Ph3P)10(dpa)2Cl(SO3CF3)2 (Au23, dpa=dipyridylamido) has been successfully synthesized. Single crystal structural determination reveals that Au23 has eight uncoordinated gold atoms in the shape of a distorted bicapped triangular prism. The accessibility of the exposed Au atoms has been confirmed quantitatively by luminescent titration with 2‐naphthalenethiol. This cluster has excellent performance toward selective oxidation of benzyl alcohol to benzaldehyde and demonstrates excellent stability due to the protection of negatively charged multidentate ligand dpa.
A stable Au23 nanocluster with preorganized open sites has been conducted through surface geometric mismatch strategy. The 35 % accessibility of Au23 was confirmed by luminescent titration with 2‐naphthalenethiol. The preorganized open sites make intact Au23 a high‐performance catalyst for aerobic oxidation of benzyl alcohol.
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