Superalkalis are clusters or molecules featuring lower ionization energies (IEs) than that of cesium atoms, and thus exhibit excellent reducing properties. Such special species have great potential ...to be used in the synthesis of unusual charge‐transfer salts and cluster‐assembled nanomaterials with tailored properties, in the reduction of carbon dioxide, or as hydrogen storage materials and noble‐gas‐trapping agents, etc. In this regard, ongoing efforts have been devoted to designing and characterizing superalkalis of new types. The recent progress on the study of superalkalis in terms of theoretical design, characterization, and potential application is summarized in this minireview. We hope this review will not only provide a broad overview of this research field, but also highlight the prospect of further extending the experimental synthesis and practical application of superalkalis.
Alkalis with super powers: Superalkalis, as special species featuring excellent reducing ability, have received increasing research interest in recent years. This minireview summarizes the recent progress made in the design, characterization, and application of superalkalis.
Metal–organic complexes assembled from coordinative interactions are known to be able to display a wide range of photoluminescent behaviors benefiting from an extensive number of metal ions, organic ...linkers, and inclusion guests, depending on the multifaceted nature of their chemical structures and photophysical properties. In the past two decades, the white-light-emitting (WLE) and photoluminescent color-tuning (PLCT) materials based on the single-phase metal–organic coordination assemblies have merited particular attention and gained substantial advances. In this review, we give an overview of recent progress in this field, placing emphasis on the WLE and PLCT properties realized in the single-phase materials, which covers the origin, generation, and manipulation of different types of photoluminescence (PL) derived from ligand-centered (LC), metal/cluster-centered (MC or CC), excimer/exciplex-based (EX), metal-to-ligand or ligand-to-metal charge-transfer-based (MLCT or LMCT), or guest-included emissions. The coordination assemblies in this topic can be generally classified into three categories (1) mono/homometallic coordination assemblies based on main group (s,p-block), transition (d-block), or lanthanide (f-block) metal centers, (2) s/p–f-, d–f-, or f–f-type heterometallic coordination assemblies, and (3) guest-included coordination assemblies for which WLE and PLCT properties can be achieved by virtue of either a wide-band/overlapped emission covering the whole visible spectrum from a single emitting center or a combination of complementary color emissions from multiple emitting centers/origins. Some state-of-the-art assembly methods and successful design models relevant to the above three categories are elaborated to demonstrate how to achieve efficient and controllable white-light emission in a single-phase material through a tunable PL approach. Potential applications in the fields of lighting and displaying, sensing and detecting, and barcoding and patterning are surveyed, and at the end, possible prospects and challenges for future development along this line are proposed.
Porphyry copper deposits account for more than 80% of the world’s total Cu resources. However, the formation mechanism and controlling factors of porphyry copper deposits remain obscure. Previous ...studies have revealed that porphyry copper deposits are usually associated with oxidized, calc-alkalic, adakitic shallow intrusive rocks. Here we show that hematite–magnetite intergrowths are commonly found in porphyry copper deposits, suggesting high and fluctuating oxygen fugacity (fO2). Oxidation promotes the destruction of sulfides in the magma source, and thereby increases initial chalcophile element concentrations. Sulfide remains undersaturated during the evolution of oxidized sulfur-enriched magmas where sulfate is the dominant sulfur species, leading to high chalcophile element concentrations in evolved magmas. The final porphyry copper mineralization is controlled by sulfate reduction, which starts with magnetite crystallization, accompanied by decreasing pH and correspondingly increasing fO2. Hematite forms once sulfate reduction lowers the pH sufficiently and the fO2 reaches the hematite–magnetite oxygen fugacity buffer, which in turn increases the pH for a given fO2. The oxidation of ferrous iron during the crystallization of magnetite and hematite is the causal process of sulfate reduction and consequent mineralization. Therefore, the initial pH and fO2 ranges of porphyries favorable for porphyry copper mineralization are defined by the hematite–magnetite oxygen fugacity buffer and SO42−–HS−–S3− reaction lines. Adakitic rocks have higher initial contents of copper, sulfur and iron than normal arc rocks, and thus are the best candidates for porphyry copper deposits. These provide a plausible explanation for the formation of copper porphyry deposits. The hematite–magnetite intergrowth marks the upper limits of fO2 favorable for the mineralization, and thus may be a powerful tool for future prospecting of large porphyry copper deposits.
This study aimed to investigate the effects of the original thickness on the densification, microstructure, and nanoindentation hardness of silicon carbide (SiC) ceramics prepared by the spark plasma ...sintering (SPS) process. The densification of SiC ceramics with different initial thicknesses ranging from 50 to 2000 µm was investigated in combination with varying SPS sintering temperature at 1700–1900°C. The results indicated that the densification of SiC sample with the initial thickness of 50 µm was complete after sintering at 1700°C. On the contrary, when the initial thickness exceeded 50 µm, it resulted in a porous microstructure. When the initial thickness varied from 50 to 100 µm, dense SiC monolithic could be obtained after sintering at 1800°C. All the samples were fully densified after sintering at 1900°C. The predominant factors for the thickness effect were mainly derived from the unique characteristics of SPS. The hardness of SiC ceramics was measured using nanoindentation, and it was found to have a strong correlation with the initial thickness, mainly attributed to the densification status. The dense SiC product demonstrated nanoindentation hardness with high values of ∼28.0 GPa.
We study the magnetic moments and transition magnetic moments of Pc and Pcs states in the molecular picture. We first revisit the magnetic moments of Pc (4312), Pc (4440), and Pc (4457) as the S-wave ...molecular states without coupled channel effects. The coupled channel effects and the D-wave contributions are then investigated carefully. The coupled channel effects contribute to the change of 0.1∼0.4 nuclear magneton μN for most cases while the D wave only induces the variation of less than 0.03 μN. In addition, we obtain the transition magnetic moments between different P c states and the related electromagnetic decay widths of Pc′ → Pcγ. The magnetic moments of Pcs (4459) are much different for the assumption of spin being 1/2 or 3/2. The study of electromagnetic properties will help us disclose further the structure of these unconventional states.
Emerging evidence indicates that the long noncoding RNAs extensively participate in cancer progression. Nevertheless, the molecular pathogenesis of how these lncRNAs regulate tumorigenesis has not ...been fully elucidated especially in hepatocellular carcinoma (HCC). Here, we sought to define the role of a novel lncRNA named lncRNA-NEF in modulating epithelial to mesenchymal transition (EMT) in HCC. It was found that the lncRNA-NEF was transcriptionally activated by EMT suppressor FOXA2 and frequently downregulated in HCC cell lines as well as clinical specimens. Although enhanced expression of lncRNA-NEF did not affect tumor cell growth, ectopic expression of lncRNA-NEF significantly suppressed EMT program and cell migration. Animal studies validated that lncRNA-NEF alleviated in vivo tumor metastasis and protected mice from tumor-induced mortality. Interestingly, we verified that lncRNA-NEF acted as a novel activator of its neighbor gene FOXA2, which formed a positive feedback loop. Subsequent studies revealed that lncRNA-NEF physically interacted with β-catenin to increase the binding of GSK3β with β-catenin and therefore promoted the inhibitory phosphorylation of β-catenin, leading to the suppression on Wnt/β-catenin signaling and activation of FOXA2 expression. Hence, our findings illustrated a novel feedback loop including FOXA2 and its neighboring gene lncRNA-NEF, which might provide mechanistic insights into the metastatic progress of HCC.
Starting from metal oxides, B4C and graphite, a suite of high-entropy boride ceramics, formulated (Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2, (Hf0.2Zr0.2Mo0.2Nb0.2Ti0.2)B2 and (Hf0.2Mo0.2Ta0.2Nb0.2Ti0.2)B2 ...derived from boro/carbothermal reduction at 1600 °C were fabricated by spark plasma sintering at 2000 °C. It was found that the synthetic high-entropy boride crystalized in hexagonal structure and the yield of the targeting phase was calculated to be over 93.0 wt% in the sintered ceramics. Benefitting from the nearly full densification (96.3% ˜ 98.5% in relative density) and the refined microstructure, the products exhibited the relatively high Vickers hardness. The indentation fracture toughness was determined to be comparable with the single transition metal-diboride ceramics. It should be noted that the formation of high-entropy boride ceramics were featured with the relatively high hardness at no expense of the fracture toughness.
To compare twenty-two machine learning (ML) models against logistic regression on survival prediction in severe traumatic brain injury (STBI) patients in a single center study.
Data was collected ...from STBI patients admitted to the Sichuan Provincial People's Hospital between December 2009 and November 2011. Twenty-two machine learning (ML) models were tested, and their predictive performance compared with logistic regression (LR) model. Receiver operating characteristics (ROC), area under curve (AUC), accuracy, F-score, precision, recall and Decision Curve Analysis (DCA) were used as performance metrics.
A total of 117 patients were enrolled. AUC of all ML models ranged from 86.3% to 94%. AUC of LR was 83%, and accuracy was 88%. The AUC of Cubic SVM, Quadratic SVM and Linear SVM were higher than that of LR. The precision ratio of LR was 95% and recall ratio was 91%, both were lower than most ML models. The F-Score of LR was 0.93, which was only slightly better than that of Linear Discriminant and Quadratic Discriminant.
The twenty-two ML models selected have capabilities comparable to classical LR model for outcome prediction in STBI patients. Of these, Cubic SVM, Quadratic SVM, Linear SVM performed significantly better than LR.
•22machine learning algorithms and logistic regression (baseline) were used to predict the outcome of STBI.•40 clinical indictors were considered as risk factors associated with the outcome of STBI.•Cubic SVM, Quadratic SVM and linear SVM are the best algorithms of performance.
The detection of glucose has important significance in clinical medicine and the food industry, especially in the diagnosis of diabetes. In recent years, electrochemical non-enzymatic glucose sensors ...have attracted intensive attention to detect the glucose level with great progress. In this review, we summarize a variety of non-enzymatic glucose sensor materials, including precious metals Pt, Au and their alloy metals, non-precious transition metals and their metal oxides, composites and other functional materials. Moreover, fundamental insights into the reaction mechanism and influencing factors of materials are given. Finally, this review discusses the perspectives and challenges of future developments in electrochemical non-enzymatic glucose detection.
This review summarizes recent advances in the development of electrocatalysts for non-enzymatic glucose detection. The sensing mechanism and influencing factors are discussed, and the perspectives and challenges are also addressed.
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