Among over 200 COVID-19 affected countries, some are fighting to "flatten the curve", while some others are considering reopening after lockdown. It remains unclear how different reopening strategies ...obstruct the local virus containment and impact the economy. We develop a model with travelers across heterogeneous epicenters. A low-risk area attempts to safely reopen utilizing internal policies, such as social distancing and contact tracing, and external policies, including capacity quota, quarantine, and tests. Simulations based on the COVID-19 scenario show that external policies differ in efficacy. They can substitute each other and complement internal policies. Simultaneous relaxation of both channels may lead to a new wave of COVID-19 and large economic costs. This work highlights the importance of quantitative assessment prior to implementing reopening strategies.
A strategy to covalently connect crystalline covalent organic frameworks (COFs) with semiconductors to create stable organic–inorganic Z‐scheme heterojunctions for artificial photosynthesis is ...presented. A series of COF–semiconductor Z‐scheme photocatalysts combining water‐oxidation semiconductors (TiO2, Bi2WO6, and α‐Fe2O3) with CO2 reduction COFs (COF‐316/318) was synthesized and exhibited high photocatalytic CO2‐to‐CO conversion efficiencies (up to 69.67 μmol g−1 h−1), with H2O as the electron donor in the gas–solid CO2 reduction, without additional photosensitizers and sacrificial agents. This is the first report of covalently bonded COF/inorganic‐semiconductor systems utilizing the Z‐scheme applied for artificial photosynthesis. Experiments and calculations confirmed efficient semiconductor‐to‐COF electron transfer by covalent coupling, resulting in electron accumulation in the cyano/pyridine moieties of the COF for CO2 reduction and holes in the semiconductor for H2O oxidation, thus mimicking natural photosynthesis.
Here comes the sun: A strategy to covalently connect covalent organic frameworks with semiconductors to create organic–inorganic Z‐scheme heterojunctions was developed and applied for the CO2 photoreduction with H2O. This work delivers new insights for the future design of Z‐scheme organic–inorganic heterojunctions for artificial photosynthesis.
Abstract
The oxidized platinum (Pt) can exhibit better electrocatalytic activity than metallic Pt
0
in the hydrogen evolution reaction (HER), which has aroused great interest in exploring the role of ...oxygen in Pt-based catalysts. Herein, we select two structurally well-defined polyoxometalates Na
5
H
3
Pt
(IV)
W
6
O
24
(PtW
6
O
24
) and Na
3
K
5
Pt
(II)
2
(W
5
O
18
)
2
(Pt
2
(W
5
O
18
)
2
) as the platinum oxide model to investigate the HER performance. Electrocatalytic experiments show the mass activities of PtW
6
O
24
/C and Pt
2
(W
5
O
18
)
2
/C are 20.175 A mg
−1
and 10.976 A mg
−1
at 77 mV, respectively, which are better than that of commercial 20% Pt/C (0.398 A mg
−1
). The in situ synchrotron radiation experiments and DFT calculations suggest that the elongated Pt-O bond acts as the active site during the HER process, which can accelerate the coupling of proton and electron and the rapid release of H
2
. This work complements the knowledge boundary of Pt-based electrocatalytic HER, and suggests another way to update the state-of-the-art electrocatalyst.
Exploring high-performance electrocatalysts for sustainable hydrogen production is an essential prerequisite of a further hydrogen economy. Integrating multiple interfaces in two-component ...electrocatalysts is expected to be a feasible strategy to optimize the intrinsic electronic structure of hybrid catalysts and improve their catalytic property. Herein, we report a new type of multi-interfacial nickel/tungsten carbide (Ni/WC) hybrid nanoparticles anchored on N-doped carbon sheets (Ni/WC@NC), which can efficiently and robustly catalyze the hydrogen evolution reaction (HER) with striking kinetic metrics in a wide pH range. In 0.5 M H 2 SO 4 , Ni/WC@NC displays a low overpotential (53 mV at current density of 10 mA cm −2 ), a small Tafel slope (43.5 mV dec −1 ), a high exchange current density (0.83 mA cm −2 ), as well as excellent stability, outperforming most of the current noble-metal-free electrocatalysts. A series of controlled experiments, DFT calculations and in situ XAS measurements reveal that the remarkable HER activity is mainly attributed to abundant interfaces between Ni and WC domains, which induce a synergistic optimization of the electronic configuration of Ni and WC through electron transfer process from WC to Ni along with potential mass transport, thus promoting the HER kinetics and accelerating the reaction. Our work suggests a potentially powerful interface-engineering strategy for designing high-performance electrocatalysts for the HER.
The rational design of high-efficiency and stable hydrogen evolution electrocatalysts under the condition of strong alkali is the key issue for the combination of hydrogen production with low-energy ...consumption chlor-alkali electrolysis. Herein, ultra-small Ru nanoclusters anchored on WNO nanowires covered by few-layer N-doped carbon (named Ru/WNO@C) were synthesized through a simple pyrolysis method. We demonstrate a comprehensive understanding of the hydrogen evolution reaction (HER) performance of such cable-like Ru/WNO@C electrocatalysts by combining experimental and computational techniques. The optimal catalyst Ru/WNO@C (Ru wt% = 3.37%) delivers a record-low overpotential of 2 mV at a current density of 10 mA cm
−2
, a low Tafel slope of 33 mV dec
−1
, a high mass activity of 4095.6 mA mg
−1
at an overpotential of 50 mV, and long-term durability in 1 M KOH. The superior HER activity of Ru/WNO@C is revealed to be caused by two factors using density functional theory (DFT) calculations: a moderate H adsorption free energy (Δ
G
H*
= −0.21 eV) and a rather low water dissociation barrier (Δ
G
B
= 0.27 eV). Specifically, Ru/WNO@C (Ru wt% = 3.37%) shows more remarkable HER performance than industrial low carbon steel under a simulated chlor-alkali electrolyte at 90 °C, making it an efficient cathode candidate applied in chlor-alkali electrolysis. Finally, a homemade ionic membrane electrolyzer with a Ru/WNO@C (Ru wt% = 3.37%) (−)//RuO
2
/IrO
2
-coated Ti-mesh (+) couple presents a low cell voltage of 2.48 V at a current density of 10 mA cm
−2
, which is 320 mV lower than the value for the low carbon steel (−)//RuO
2
/IrO
2
-coated Ti-mesh (+) (2.8 V) couple, exhibiting robust stability for 25 h. This work provides a meaningful reference for the design and fabrication of efficient and stable alkaline HER catalysts, and realizes high-efficiency hydrogen production and low-energy consumption chlor-alkali electrolysis at the same time.
An efficient and durable hydrogen evolution electrocatalyst (Ru/WNO@C) in simulated chlor-alkali electrolytes illuminates the prospect of hydrogen and chlor-alkali co-production.
Programmed cell death ligand 1 (PD‐L1), inducing T cell exhaustion to facilitate immune escape of tumor cells, is upregulated by interleukin 6 (IL‐6) in T cell lymphoma and ovarian cancer. The ...purpose of this study is to investigate the expression of IL‐6 and PD‐L1 in thyroid cancer, and whether IL‐6 regulates PD‐L1 expression. As a result, IL‐6 and PD‐L1 were highly expressed in thyroid cancer tissues. Multivariate logistic analysis showed that tumor size, distant metastasis, and risk stratification were significantly associated with IL‐6 expression (P < .05), and multifocality, lymph node metastasis, distant metastasis, risk stratification, and IL‐6 expression were identified as the independent predictors of PD‐L1 expression (P < .05). The invasiveness of thyroid cancer was significantly enhanced after IL‐6 treatment or PD‐L1 overexpression. PD‐L1 positive rate correlated with IL‐6 expression in cancer tissues (P < .001), and after IL‐6 treatment, the PD‐L1 expression in TPC‐1 and BCPAP significantly increased. The mitogen‐activated protein kinase pathway (MAPK) and the Janus‐activated kinase (JAK)–signal transducers and activators of transcription 3 (STAT3) signaling pathways were activated by IL‐6, and the IL‐6–induced PD‐L1 expression decreased after treatment with these two signaling pathway inhibitors. Knockdown of transcription factors c‐Jun and stat3 suppressed the expression of PD‐L1 induced by IL‐6, and these two factors could bind to PD‐L1 gene promoter directly and promote its transcription. It is concluded that IL‐6 and PD‐L1 are overexpressed in thyroid cancer and are related to tumor invasiveness. IL‐6 upregulates PD‐L1 expression through the MAPK and JAK‐STAT3 signaling pathways, which function via transcription factors c‐Jun and stat3.
IL‐6 and PD‐L1 are highly expressed in thyroid cancer and correlate with disease aggressiveness. IL‐6 activates the MAPK and JAK‐STAT3 signaling pathways in thyroid cancer. In addition, IL‐6 promotes PD‐L1 transcription through the MAPK and JAK‐STAT3 signaling pathways, which function via transcription factors c‐Jun and stat3.
A Z-scheme heterostructure is a kind of highly efficient photocatalyst that can not only reduce the forbidden band width of the semiconductor but also promote the redox reaction in the photocatalytic ...system. Herein, calculations on the work function and charge density difference by density functional theory (DFT) methods prove that g-C3N4/SnS2 and B-doped g-C3N4/SnS2 are Z-scheme heterostructures. Compared to g-C3N4, the Z-scheme heterostructures show narrower band gaps, and red-shifted and stronger light absorption with remarkably improved photocatalytic activity. The reaction free energy for each step of the CO2 reduction process was calculated to further evaluate the photocatalytic activity of g-C3N4/SnS2 and B-doped g-C3N4/SnS2. The products of CO2RR catalyzed by g-C3N4/SnS2 are CH3OH and CH4, which are in good agreement with experiments, and the rate-determining step is CO2 → COOH* with a ΔG of 1.10 eV. For B-doped g-C3N4/SnS2, the optimal path is CO2 → COOH* → CO* → HCO* → CHOH* → CH* → CH2* → CH3* → CH4, and the rate-determining step is CH2* → CH3* with a ΔG of 0.40 eV. The results show that the CO2 reduction activity of B-doped g-C3N4/SnS2 is better than that of g-C3N4/SnS2. Therefore, the Z-scheme B-doped g-C3N4/SnS2 heterostructure is predicted to be a promising catalyst for CO2 reduction to CH4.
A physical modeling approach was adopted to build a Digital Electro-Hydraulic Control (DEH) system simulation model and the fault models using the SIMULINK tool. This research combined the advantages ...of the gray system and neural network to build a multi-parameter gray error neural network fault prediction model for the first time. Furthermore, an embedded platform for intelligent fault diagnosis and prediction was developed using an Application Specific Integrated Circuit chip. The results show that the simulation model of the DEH system has good performance. A jam fault, internal leakage, and a device fault could be accurately identified through the fault diagnosis model. The multi-parameter gray error neural network prediction model improves the accuracy of fault prediction. The embedded platform developed by the Application Specific Integrated Circuit chip solves the problem of transmission limitation and insufficient computing power. It realizes the intelligent diagnosis and prediction of DEH system faults and guarantees the regular operation of the DEH system.
The electrocatalytic carbon dioxide (CO
2
) reduction reaction (CO
2
RR) involves a variety of electron transfer pathways, resulting in poor reaction selectivity, limiting its use to meet future ...energy requirements. Polyoxometalates (POMs) can both store and release multiple electrons in the electrochemical process, and this is expected to be an ideal "electron switch" to match with catalytically active species, realize electron transfer modulation and promote the activity and selectivity of the electrocatalytic CO
2
RR. Herein, we report a series of new POM-based manganese-carbonyl (MnL) composite CO
2
reduction electrocatalysts, whereby SiW
12
-MnL exhibits the most remarkable activity and selectivity for CO
2
RR to CO, resulting in an increase in the faradaic efficiency (FE) from 65% (MnL) to a record-value of 95% in aqueous electrolyte. A series of control electrochemical experiments, photoluminescence spectroscopy (PL), transient photovoltage (TPV) experiments, and density functional theory (DFT) calculations revealed that POMs act as electronic regulators to control the electron transfer process from POM to MnL units during the electrochemical reaction, enhancing the selectivity of the CO
2
RR to CO and depressing the competitive hydrogen evolution reaction (HER). This work demonstrates the significance of electron transfer modulation in the CO
2
RR and suggests a new idea for the design of efficient electrocatalysts towards CO
2
RR.
Polyoxometalates as electron regulators to promote the carbonyl manganese (MnL) electrocatalyst for highly efficient CO
2
reduction in aqueous electrolyte.
Due to its growing application in various industries as a marketing tool, the travel industry is increasingly perceiving the potential of virtual reality (VR) in the tourism arena. Although VR has ...been widely discussed in practice management research, there is, however, little knowledge on how VR technology can be applied in themed tourism environments. Hence, in this study, we use the Zaltman Metaphor Elicitation Technique (ZMET) to empirically study how visitors express their inner values and meanings through VR-themed tourism. We invited 26 respondents to participate in a VR-themed tourism experience, and we organized our results based on three key themes. First, characteristics of VR-themed tourism such as 'freedom of virtual reality', 'escapism of virtual reality' and 'anxiety of virtual reality' were summarized. Second, an objective consensus map was created using the 'conservative', 'average' and 'optimistic' calculation procedures. Third, we determined the relevance of the integrated linking constructs. We found that 'imagination' and 'fantasy dream' have the highest relevance value, followed by 'illusion' and 'illusionary situation'. These themes could thus provide new insights into the possible intertwined integration and complexity of 'virtual' and 'physical' issues that may arise when tourists experience VR-themed tourism.
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