A series of zirconium polyphenolate‐decorated‐(metallo)porphyrin metal–organic frameworks (MOFs), ZrPP‐n (n = 1, 2), featuring infinite ZrIV‐oxo chains linked via polyphenolate groups on four ...peripheries of eclipse‐arranged porphyrin macrocycles, are successfully constructed through a top–down process from simulation to synthesis. These are the unusual examples of Zr‐MOFs (or MOFs in general) based on phenolic porphyrins, instead of commonly known carboxylate‐based types. Representative ZrPP‐1 not only exhibits strong acid resistance (pH = 1, HCl) but also remains intact even when immersed in saturated NaOH solution (≈20 m), an exceptionally large range of pH resistance among MOFs. The metallation at the porphyrin core gives rise to materials with enhanced sorption and catalytic properties. In particular, ZrPP‐1‐Co, with precise and uniform distribution of active centers, exhibits not only high CO2 trapping capability (≈90 cm3 g−1 at 1 atm, 273 K, among the highest in Zr‐MOFs) but also high photocatalytic activity for reduction of CO2 into CO (≈14 mmol g−1 h−1) and high selectivity over CH4 (>96.4%) without any cocatalyst under visible‐light irradiation (λ > 420 nm). Given the strong chemical resistance under extreme alkali conditions, these catalysts can be recycled without appreciable loss of activity. The possible mechanism for photocatalytic reduction of CO2‐to‐CO over ZrPP‐1‐Co is also proposed.
Top–down fabrication of robust and porous materials based on infinite ZrIV‐polyphenolate chains linked via eclipsed‐arranged porphyrin macrocycles is presented. Among them, ZrPP‐1 retains its framework integrity when immersed in saturated NaOH solution as long as 1 week. Moreover, metallation at the porphyrin core gives rise to materials with enhanced CO2 trapping capability and high visible‐light‐driven CO2‐to‐CO photoreduction activity.
Potassium ion batteries (KIBs) have emerged as a promising energy storage system, but the stability and high rate capability of their electrode materials, particularly carbon as the most investigated ...anode ones, become a primary challenge. Here, it is identified that pitch‐derived soft carbon, a nongraphitic carbonaceous species which is paid less attention in the battery field, holds special advantage in KIB anodes. The structural flexibility of soft carbon makes it convenient to tune its crystallization degree, thereby modulating the storage behavior of large‐sized K+ in the turbostratic carbon lattices to satisfy the need in structural resilience, low‐voltage feature, and high transportation kinetics. It is confirmed that a simple thermal control can produce structurally optimized soft carbon that has much better battery performance than its widely reported carbon counterparts such as graphite and hard carbon. The findings highlight the potential of soft carbon as an interesting category suitable for high‐performance KIB electrode and provide insights for understanding the complicated K+ storage mechanisms in KIBs.
The cycling stability of anode materials in potassium‐ion batteries (KIBs) is challenged by the large size of K+ itself. The findings not only demonstrate the promising potential of soft carbon as a category suitable for high‐performance KIB electrodes, but also provide insights into the complicated K+ storage mechanisms in carbon anodes of KIBs.
In this study, we test the efficient market hypothesis for a number of sectors in the US stock market during the COVID-19 pandemic to identify its effects on individual sectors. To test this ...hypothesis, we define the average price for 11 sectors within the S&P 500 and apply multifractal detrended fluctuation analysis to the average return series. Furthermore, we also investigate these sectors’ efficiency and multifractality during the global financial crisis (GFC) to analyze the features of the COVID-19 pandemic. Our findings can be summarized as follows. First, the average return series show non-persistent and persistent features during the GFC and the COVID-19 pandemic, respectively. Second, during each of these crisis periods, the consumer discretionary and utilities sectors had the highest and lowest levels of efficiency, respectively. Third, while both long-range correlations and fat-tailed distribution contributed to the multifractal properties, the latter of these was the chief contributor. Furthermore, the lower the efficiency ranking, the greater the impact of the fat-tailed distribution on multifractality. Finally, we classify sectors with low market efficiency for the two crisis periods. These findings have several important implications for asset allocations by investors in US stock markets.
•We test the EMH for a number of industries in the US stock market during COVID-19.•We also investigate their efficiency and multifractality during the GFC.•The CD and UTI sectors have the highest and lowest efficiency, respectively.•The fat-tailed distribution had a greater impact than on the long-range correlation.•We classify sectors with low market efficiency for the two crisis periods.
Corrosion of materials not only accounts for about 3 to 4% of economic losses in GDP in an industrial nation, but it also contributes significantly to greenhouse emissions and climate change because ...material production is one of the largest greenhouse emitters ....
Conventional 3D organic–inorganic halide perovskites have recently undergone unprecedented rapid development. Yet, their inherent instabilities over moisture, light, and heat remain a crucial ...challenge prior to the realization of commercialization. By contrast, the emerging 2D Ruddlesden−Popper‐type perovskites have recently attracted increasing attention owing to their great environmental stability. However, the research of 2D perovskites is just in their infancy. In comparison to 3D analogues, they are natural quantum wells with a much larger exciton binding energy. Moreover, their inner structural, dielectric, optical, and excitonic properties remain to be largely explored, limiting further applications. This review begins with an introduction to 2D perovskites, along with a detailed comparison to 3D counterparts. Then, a discussion of the organic spacer cation engineering of 2D perovskites is presented. Next, quasi‐2D perovskites that fall between 3D and 2D perovskites are reviewed and compared. The unique excitonic properties, electron–phonon coupling, and polarons of 2D perovskites are then be revealed. A range of their (opto)electronic applications is highlighted in each section. Finally, a summary is given, and the strategies toward structural design, growth control, and photophysics studies of 2D perovskites for high‐performance electronic devices are rationalized.
Recent advances in 2D organometal halide perovskites are reviewed. A comprehensive comparison between 3D and 2D perovskites is provided, including crystal structure and orientation, transport dynamics, and optoelectronic performance. Among them, organic spacer engineering and modulating physical properties of 2D perovskites are highlighted. Finally, future developments and possible strategies to the unsolved challenges are outlined.
•We investigate the impact of economic uncertainty due to the coronavirus (COVID-19) pandemic on the industrial economy in the US.•We apply wavelet coherence analysis to economic policy uncertainty ...(EPU) data and monthly sector volatility of the S&P 500 index.•Our analysis indicates that COVID-19 has had a substantial impact on all sectors of the US stock market.•The influence of the pandemic on the industrial economy is larger than that of the global financial crisis (GFC) for all sectors.
This study investigates the impact of economic uncertainty due to the coronavirus (COVID-19) pandemic on the industrial economy in the US in terms of the interdependence and causality relationship. We apply wavelet coherence analysis to economic policy uncertainty (EPU) data and monthly sector volatility of the S&P 500 index from January 2008 to May 2020. The results reveal that EPU in terms of COVID-19 has influenced the sector volatility more than the global financial crisis (GFC) for all sectors. Furthermore, EPU leads the volatility of all sectors during COVID-19 pandemic, while some sector’s volatilities lead EPU during the GFC.
The corrosion of a material results from its interaction with the surrounding environment, which can lead to physical and chemical changes in the material and the loss of its functional properties .......
Treatment of non-small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) activating mutation with EGFR-TKIs has achieved great success, yet faces the development of acquired ...resistance as the major obstacle to long-term disease remission in the clinic. MET (or c-MET) gene amplification has long been known as an important resistance mechanism to first- or second-generation EGFR-TKIs in addition to the appearance of T790 M mutation. Recent preclinical and clinical studies have suggested that MET amplification and/or protein hyperactivation is likely to be a key mechanism underlying acquired resistance to third-generation EGFR-TKIs such as osimertinib as well, particularly when used as a first-line therapy. EGFR-mutant NSCLCs that have relapsed from first-generation EGFR-TKI treatment and have MET amplification and/or protein hyperactivation should be insensitive to osimertinib monotherapy. Therefore, combinatorial therapy with osimertinib and a MET or even a MEK inhibitor should be considered for these patients with resistant NSCLC carrying MET amplification and/or protein hyperactivation.
Constrained Sensitivity Filtering Method (CSFM) has been proposed to save computational expenses in topology optimization. The sensitivity filtering technique is widely adopted to avoid numerical ...instabilities. Because the filtered sensitivity values are recalculated from the normalized density values and the sensitivity values from within a fixed range of neighborhoods, the values are sometimes completely different from the original ones. Thus, the idea of the CSFM is to control the change of filtered sensitivity values based on the previous iterations. By controlling the changes of filtered sensitivity values within certain limitation, optimal layouts can be obtained with lower compliance and the computational expenses can also be reduced in comparison to that by conventional topology optimization. The computational expense with CSFM topology optimization could be reduced by up to 85%. The numerical examples established that CSFM topology optimization has improved the numerical efficiency and effectiveness.
Two new chemically stable metalloporphyrin‐bridged metal‐catechol frameworks, InTCP‐Co and FeTCP‐Co, were constructed to achieve artificial photosynthesis without additional sacrificial agents and ...photosensitizers. The CO2 photoreduction rate over FeTCP‐Co considerably exceeds that obtained over InTCP‐Co, and the incorporation of uncoordinated hydroxyl groups, associated with catechol, into the network further promotes the photocatalytic activity. The iron‐oxo coordination chain assists energy band alignment and provides a redox‐active site, and the uncoordinated hydroxyl group contributes to the visible‐light absorptance, charge‐carrier transfer, and CO2‐scaffold affinity. With a formic acid selectivity of 97.8 %, FeTCP‐OH‐Co affords CO2 photoconversion with a reaction rate 4.3 and 15.7 times higher than those of FeTCP‐ Co and InTCP‐Co, respectively. These findings are also consistent with the spectroscopic study and DFT calculation.
A series of hydro‐stable metalloporphyrin‐bridged metal‐phenate frameworks are constructed, which exhibit artificial photosynthetic activity under visible‐light irradiation without photosensitizer or sacrificial agent. Activity is boosted by substitution of the Fe‐oxo chain for an In‐oxo chain, and further enhanced by addition of the uncoordinated hydroxyl groups of catechol into the scaffold.
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