Abstract
Tuning metal–support interaction has been considered as an effective approach to modulate the electronic structure and catalytic activity of supported metal catalysts. At the atomic level, ...the understanding of the structure–activity relationship still remains obscure in heterogeneous catalysis, such as the conversion of water (alkaline) or hydronium ions (acid) to hydrogen (hydrogen evolution reaction, HER). Here, we reveal that the fine control over the oxidation states of single-atom Pt catalysts through electronic metal–support interaction significantly modulates the catalytic activities in either acidic or alkaline HER. Combined with detailed spectroscopic and electrochemical characterizations, the structure–activity relationship is established by correlating the acidic/alkaline HER activity with the average oxidation state of single-atom Pt and the Pt–H/Pt–OH interaction. This study sheds light on the atomic-level mechanistic understanding of acidic and alkaline HER, and further provides guidelines for the rational design of high-performance single-atom catalysts.
Developing red thermally activated delayed fluorescence (TADF) emitters, attainable for both high‐efficient red organic light‐emitting diodes (OLEDs) and non‐doped deep red/near‐infrared (NIR) OLEDs, ...is challenging. Now, two red emitters, BPPZ‐PXZ and mDPBPZ‐PXZ, with twisted donor–acceptor structures were designed and synthesized to study molecular design strategies of high‐efficiency red TADF emitters. BPPZ‐PXZ employs the strictest molecular restrictions to suppress energy loss and realizes red emission with a photoluminescence quantum yield (ΦPL) of 100±0.8 % and external quantum efficiency (EQE) of 25.2 % in a doped OLED. Its non‐doped OLED has an EQE of 2.5 % owing to unavoidable intermolecular π–π interactions. mDPBPZ‐PXZ releases two pyridine substituents from its fused acceptor moiety. Although mDPBPZ‐PXZ realizes a lower EQE of 21.7 % in the doped OLED, its non‐doped device shows a superior EQE of 5.2 % with a deep red/NIR emission at peak of 680 nm.
Two red emitters, BPPZ‐PXZ and mDPBPZ‐PXZ, with twisted donor–acceptor structures were designed and synthesized to study molecular design strategies of high‐efficiency red TADF emitters. BPPZ‐PXZ employs the strictest molecular restrictions to suppress energy loss and realizes red emission with a photoluminescence quantum yield (ΦPL) of 100±0.8 % and external quantum efficiency (EQE) of 25.2 % in a doped OLED.
With the rapid spread of carbon trading in the world, the interaction of carbon prices and fossil energy prices has raised growing attention, but little research has discussed their time-varying ...correlation and dynamic volatility spillover. This paper employs the threshold dynamic conditional correlation (DCC) generalized autoregressive conditional heteroscedasticity (GARCH) model and the full Baba, Engle, Kraft and Kroner (BEKK) GARCH model to explore these issues, for the daily data of European carbon futures prices and the three fossil energy prices (coal, natural gas and Brent oil) from January 2 2008 to September 30 2014. The results indicate that, first, there is significant unidirectional volatility spillover from coal market to carbon market and from carbon market to natural gas market, whereas there exists no significant volatility spillover between carbon market and Brent oil market. Second, carbon market and fossil energy markets have significantly positive correlation across time. Specifically, among the three fossil fuels, coal market has the highest correlation with carbon market, followed by natural gas and Brent oil markets. Finally, as for the three fossil fuels, their price decrease may have stronger impact on carbon price volatility than their price increase with the same degree, while there is asymmetric impact of carbon price increase and decrease only on Brent oil price volatility. These results may help investors to well configure their portfolios and manage their investment risks, and help emission trading installations to join in carbon market in a cost-effective way.
•The dynamic volatility spillover between carbon and energy markets are detected.•Significant one-way and time-varying spillover exists from coal to carbon markets.•There is also one-way and time-varying spillover from carbon to natural gas markets.•No significant volatility spillover is found between carbon and crude oil markets.•Coal market is most correlated with carbon market, followed by natural gas and oil.
Developing red thermally activated delayed fluorescence (TADF) emitters for high‐performance OLEDs is still facing great challenge. Herein, three red TADF emitters, pDBBPZ‐DPXZ, pDTBPZ‐DPXZ, and ...oDTBPZ‐DPXZ, are designed and synthesized with same donor–acceptor (D‐A) backbone with different peripheral groups attaching on the A moieties. Their lowest triplet states change from locally excited to charge transfer character leading to significantly enhance reverse intersystem crossing process. In particular, oDTBPZ‐DPXZ exhibits efficient TADF feature and exciton utilization. It not only achieves an external quantum efficiency (EQE) of 20.1 % in red vacuum‐processed OLED, but also realize a high EQE of 18.5 % in a solution‐processed OLED, which is among the best results in solution‐processed red TADF OLEDs. This work provides an effective strategy for designing red TADF molecules by managing energy level alignments to facilitate the up‐conversion process and thus enhance exciton harvesting.
By introducing phenyl or o‐tolyl groups into different positions of the same acceptor backbone, the lowest triplet energy levels of red thermally activated delayed fluorescence emitters can be tuned from locally excited triplet (3LEA) to charge transfer triplet (3CT) states, resulting in enhancement of the rates of reverse intersystem crossing (RISC), and boosting efficiencies in both vacuum‐ and solution‐processed OLEDs.
How to efficiently oxidize H2O to O2 (H2O → 1/2O2 + 2H+ + 2e−) is a great challenge for electrochemical/photo water splitting owing to the high overpotential and catalyst corrosion. Here extensive ...periodic first-principles calculations integrated with modified-Poisson−Boltzmann electrostatics are utilized to reveal the physical origin of the high overpotential of the electrocatalytic oxygen evolution reaction (OER) on RuO2(110). By determining the surface phase diagram, exploring the possible reaction channels, and computing the Tafel lines, we are able to elucidate some long-standing puzzles on the OER kinetics from the atomic level. We show that OER occurs directly on an O-terminated surface phase above 1.58 V vs NHE, but indirectly on a OH/O mixed phase below 1.58 V by converting first the OH/O mixed phase to the O-terminated phase locally. The rate-determining step of OER involves an unusual water oxidation reaction following a Eley−Rideal-like mechanism, where a water molecule from solution breaks its OH bond over surface Os with concurrent new OOH bond formation. The free energy barrier is 0.74 eV at 1.58 V, and it decreases linearly with the increase of potential above 1.58 V (a slope of 0.56). In contrast, the traditionally regarded surface oxygen coupling reaction with a Langmuir−Hinshelwood mechanism is energetically less favored and its barrier is weakly affected by the potential. Fundamentally, we show that the empirical linear barrier∼potential relation is caused by the linear structural response of the solvated transition state to the change of potential. Finally, the general strategy for finding better OER anode is also presented.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to the coronavirus disease 2019 (COVID-19) pandemic, severely affecting public health and the global economy. Adaptive immunity ...plays a crucial role in fighting against SARS-CoV-2 infection and directly influences the clinical outcomes of patients. Clinical studies have indicated that patients with severe COVID-19 exhibit delayed and weak adaptive immune responses; however, the mechanism by which SARS-CoV-2 impedes adaptive immunity remains unclear. Here, by using an in vitro cell line, we report that the SARS-CoV-2 spike protein significantly inhibits DNA damage repair, which is required for effective V(D)J recombination in adaptive immunity. Mechanistically, we found that the spike protein localizes in the nucleus and inhibits DNA damage repair by impeding key DNA repair protein BRCA1 and 53BP1 recruitment to the damage site. Our findings reveal a potential molecular mechanism by which the spike protein might impede adaptive immunity and underscore the potential side effects of full-length spike-based vaccines.
Although immune cell therapy has long been used for treating solid cancer, its efficacy remains limited. Interferon (IFN)-producing killer dendritic cells (IKDCs) exhibit cytotoxicity and present ...antigens to relevant cells; thus, they can selectively induce tumor-associated antigen (TAA)-specific CD8 T cells and may be useful in cancer treatment. Various protocols have been used to amplify human IKDCs from peripheral sources, but the complexity of the process has prevented their widespread clinical application. Additionally, the induction of TAA-specific CD8 T cells through the adoptive transfer of IKDCs to immunocompromised patients with cancer may be insufficient. Therefore, we developed a method for generating an immune cell-based regimen, Phyduxon-T, comprising a human IKDC counterpart (Phyduxon) and expanded TAA-specific CD8 T cells.
Peripheral blood mononuclear cells from ovarian cancer patients were cultured with human interleukin (hIL)-15, hIL-12, and hIL-18 to generate Phyduxon-T. Then, its phenotype, cytotoxicity, and antigen-presenting function were evaluated through flow cytometry using specific monoclonal antibodies.
Phyduxon exhibited the characteristics of both natural killer and dendritic cells. This regimen also exhibited cytotoxicity against primary ovarian cancer cells and presented TAAs, thereby inducing TAA-specific CD8 T cells, as evidenced by the expression of 4-1BB and IFN-γ. Notably, the Phyduxon-T manufacturing protocol effectively expanded IFN-γ-producing 4-1BB
TAA-specific CD8 T cells from peripheral sources; these cells exhibited cytotoxic activities against ovarian cancer cells.
Phyduxon-T, which is a combination of natural killer cells, dendritic cells, and TAA-specific CD8 T cells, may enhance the efficacy of cancer immunotherapy.
The Tafel equation is of fundamental importance in electrochemical kinetics, formulating a quantitative relation between the current and the applied electrochemical potential. The recent years have ...seen the rapid expansion and development in the application of first-principles density functional theory (DFT) simulation on electrocatalytic reactions that occur at the solid–liquid interface. This article reviews the current theoretical methods for electrochemistry modeling, in particular, those for the direct computation of Tafel kinetics of electrocatalytic reactions on surfaces based on DFT calculations. Representative reactions, namely, hydrogen evolution and oxygen evolution reactions, are selected to illustrate how the theoretical methods are applied to compute quantitatively the kinetics of multiple-step electrochemical reactions. We summarize in detail the computation procedure based on the first-principles periodic continuum solvation method for obtaining the charge transfer coefficient (CTC) and deducing the potential-dependent reaction rate. The theoretical results on the Tafel kinetics of electrochemical reactions are generalized and discussed.
Copper (Cu) is an essential micronutrient for all living organisms but is also highly toxic in excess. Cellular homoeostasis of Cu is maintained by various transporters and metallochaperones. Here, ...we investigated the biological function of OsCOPT7, a member of the copper transporters (COPT) family, in Cu homoeostasis in rice. OsCOPT7 was mainly expressed in the roots and the expression was upregulated by Cu deficiency. OsCOPT7 was localized at the tonoplast and the endoplasmic reticulum. Knockout of OsCOPT7 increased Cu accumulation in the roots but decreased Cu concentrations in the shoots and grain. The knockout mutants contained higher concentrations of Cu in the roots cell sap but markedly lower concentrations of Cu in the xylem sap than wild‐type plants. Seed setting and grain yield were reduced significantly in the knockout mutants grown in a low Cu soil. Knockout mutants were more tolerant to Cu toxicity. Yeast two‐hybrid and bimolecular fluorescence complementation assays showed that OsCOPT7 interacts physically with the rice Cu chaperone antioxidant protein 1 (OsATX1). Taken together, our results indicate that OsCOPT7 is a specific Cu transporter functioning to export Cu from the vacuoles and the ER and plays an important role in controlling the root‐to‐shoot Cu translocation in rice.
Summary statement
Copper (Cu) is an essential micronutrient for all living organisms but is also highly toxic in excess. Cellular homoeostasis of Cu is maintained by various transporters and metallochaperones. We show that OsCOPT7 is a Cu transporter functioning to export Cu from the vacuoles and the endoplasmic reticulum and plays an important role in controlling the root‐to‐shoot Cu translocation in rice.
The combination of diagnostic and therapeutic functions in a single theranostic nanoagent generally requires the integration of multi‐ingredients. Herein, a cytotoxic near‐infrared (NIR) dye (IR‐797) ...and its nanoassembly are reported for multifunctional cancer theranostics. The hydrophobic IR‐797 molecules are self‐assembled into nanoparticles, which are further modified with an amphiphilic polymer (C18PMH‐PEG5000) on the surface. The prepared PEG‐IR‐797 nanoparticles (PEG‐IR‐797 NPs) possess inherent cytotoxicity from the IR‐797 dye and work as a chemotherapeutic drug which induces apoptosis of cancer cells. The IR‐797 NPs are found to have an ultrahigh mass extinction coefficient (444.3 L g−1 cm−1 at 797 nm and 385.9 L g−1 cm−1 at 808 nm) beyond all reported organic nanomaterials (<40 L g−1 cm−1) for superior photothermal therapy (PTT). In addition, IR‐797 shows some aggregation‐induced‐emission (AIE) properties. Combining the merits of good NIR absorption, high photothermal energy conversion efficiency, and AIE, makes the PEG‐IR‐797 NPs useful for multimodal NIR AIE fluorescence, photoacoustic, and thermal imaging‐guided therapy. The research exhibits the possibility of using a single ingredient and entity to perform multimodal NIR fluorescence, photoacoustic, and thermal imaging‐guided chemo‐/photothermal combination therapy, which may trigger wide interest from the fields of nanomedicine and medicinal chemistry to explore multifunctional theranostic organic molecules.
The combination of chemotherapy and photothermal therapy in a single component entity is desirable to explore for improvement of cancer treatment outcomes through synergistic effects. PEG‐IR‐797 nanoparticles that possess intrinsic cytotoxicity, excellent photothermal effects, and multimodal NIR fluorescence/photoacoustic/photothermal imaging are reported, which could be promising for precise multimodal imaging and enhanced cancer therapy outcomes through synergistic chemo‐/photothermal combination therapy.
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