Nitrate electrocatalytic reduction (NO3RR) for ammonia production is a promising strategy to close the N‐cycle from nitration contamination, as well as an alternative to the Haber–Bosch process with ...less energy consumption and carbon dioxide release. However, current long‐term stability of NO3RR catalysts is usually tens of hours, far from the requirements for industrialization. Here, symmetry‐broken Cusingle‐atom catalysts are designed, and the catalytic activity is retained after operation for more than 2000 h, while an average ammonia production rate of 27.84 mg h−1 cm−2 at an industrial level current density of 366 mA cm−2 is achieved, obtaining a good balance between catalytic activity and long‐term stability. Coordination symmetry breaking is achieved by embedding one Cu atom in graphene nanosheets with two N and two O atoms in the cis‐configuration, effectively lowering the coordination symmetry, rendering the active site more polar, and accumulating more NO3− near the electrocatalyst surface. Additionally, the cis‐coordination splits the Cu 3d orbitals, which generates an orbital‐symmetry‐matched π‐complex of the key intermediate *ONH and reduces the energy barrier, compared with the σ‐complex generated with other catalysts. These results reveal the critical role of coordination symmetry in single‐atom catalysts, prompting the design of more coordination‐symmetry‐broken electrocatalysts toward possible industrialization.
A coordination‐symmetry‐breaking Cusingle‐atom catalyst enables a good balance between catalytic activity and long‐term stability in nitrate electroreduction to ammonia. The catalytic activity is retained after operation for more than 2000 h, while an average ammonia production rate of 27.84 mg h−1 cm−2 at an industrial level current density of 366 mA cm−2 is achieved.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
We report acute antibody responses to SARS-CoV-2 in 285 patients with COVID-19. Within 19 days after symptom onset, 100% of patients tested positive for antiviral immunoglobulin-G (IgG). ...Seroconversion for IgG and IgM occurred simultaneously or sequentially. Both IgG and IgM titers plateaued within 6 days after seroconversion. Serological testing may be helpful for the diagnosis of suspected patients with negative RT-PCR results and for the identification of asymptomatic infections.
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FZAB, GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In this paper, we propose a PDE-based level set method. Traditionally, interfaces are represented by the zero level set of continuous level set functions. Instead, we let the interfaces be ...represented by discontinuities of piecewise constant level set functions. Each level set function can at convergence only take two values, i.e., it can only be 1 or -1; thus, our method is related to phase-field methods. Some of the properties of standard level set methods are preserved in the proposed method, while others are not. Using this new method for interface problems, we need to minimize a smooth convex functional under a quadratic constraint. The level set functions are discontinuous at convergence, but the minimization functional is smooth. We show numerical results using the method for segmentation of digital images.
As is well known, the additional low-order harmonic currents and the huge computation amount of the cost function value with all available control sets are the two special issues of ...finite-control-set model predictive current control (FCS-MPCC) for multiphase inverters. Thus, this paper proposes a FCS-MPCC scheme with duty-ratio optimization for five-phase inverters. First, a group of the reconstructed virtual voltage vectors (V 3 ) with low-order harmonic elimination is defined and employed as the control sets in FCS-MPCC scheme. Thus, it leads to no requirement for harmonic items and weighting factors existing in the cost function. Then, a combination of zero vectors and the selected V 3 during each control horizon is adopted to rearrange the pulse sequence, which can realize constant switching frequency. In addition, the durations of the selected V 3 and zero vectors during each control horizon are also estimated to minimize the steady-state current ripples in different subspaces based on the cost function optimization. Finally, a comparison of the proposed V 3 -FCS-MPCC scheme and the other FCS-MPCCs are presented in simulation and experimental test. Simulation and experimental results verify that the proposed V 3 -FCS-MPCC scheme can remain the simplified structure, fast dynamic performance, constant switching frequency, and achieve minimum current ripples in different subspaces.
Eosin Y, a well‐known economical alternative to metal catalysts in visible‐light‐driven single‐electron transfer‐based organic transformations, can behave as an effective direct hydrogen‐atom ...transfer catalyst for C−H activation. Using the alkylation of C−H bonds with electron‐deficient alkenes as a model study revealed an extremely broad substrate scope, enabling easy access to a variety of important synthons. This eosin Y‐based photocatalytic hydrogen‐atom transfer strategy is promising for diverse functionalization of a wide range of native C−H bonds in a green and sustainable manner.
Neutral eosin Y has been employed as an effective direct hydrogen‐atom transfer photocatalyst to activate a wide range of native C−H bonds in a green and sustainable fashion. This transformation is distinguished by its operational simplicity and amenability to large‐scale synthesis using continuous‐flow technology (EWG=aldehyde, ketone, ester, amide, imide, cyanide, sulfone, nitro, pyridine).
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The unsatisfactory response rate of immune checkpoint blockade (ICB) immunotherapy severely limits its clinical application as a tumor therapy. Here, we generate a vaccine-based nanosystem by ...integrating siRNA for Cd274 into the commercial human papillomavirus (HPV) L1 (HPV16 L1) protein. This nanosystem has good biosafety and enhances the therapeutic response rate of anti-tumor immunotherapy. The HPV16 L1 protein activates innate immunity through the type I interferon pathway and exhibits an efficient anti-cancer effect when cooperating with ICB therapy. For both resectable and unresectable breast tumors, the nanosystem decreases 71% tumor recurrence and extends progression-free survival by 67%. Most importantly, the nanosystem successfully induces high response rates in various genetically modified breast cancer models with different antigen loads. The strong immune stimulation elicited by this vaccine-based nanosystem might constitute an approach to significantly improve current ICB immunotherapy.
The nonlocal symmetries for the
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-dimensional Konopelchenko–Dubrovsky equation are obtained with the truncated Painlevé method and the Möbious (conformal) invariant form. The nonlocal ...symmetries are localized to the Lie point symmetries by introducing auxiliary dependent variables. The finite symmetry transformations are obtained by solving the initial value problem of the prolonged systems. The multi-solitary wave solution is presented with the finite symmetry transformations of a trivial solution. In the meanwhile, symmetry reductions in the enlarged systems are studied by the Lie point symmetry approach. Many explicit interaction solutions between solitons and cnoidal periodic waves are discussed both in analytical and in graphical ways.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Due to the modulator free structure, the finite-control-setmodel predictive control (FCS-MPC) needs a high sampling frequency/interrupt frequency (20-50 kHz) for power converters application, while ...the typical converter switching frequency is around 20-25% of the sampling frequency. To obtain a high switching frequency, it is not always practical to increase the sampling rate by considering the computational burden in a digital processor. Therefore, increasing the switching frequency without using a high sampling frequency is a critical task for FCS-MPC, particularly applied to silicon carbide and gallium nitride-based high switching frequency power converters. To solve this problem, this article proposes the multirate FCS-MPC (MRFCS-MPC), where the control frequency is allowed to be higher than the sampling frequency. Consequently, the switching frequency can be significantly increased without changing the sampling frequency. The proposed scheme inherits the ability to handle complex control objectives from the traditional FCS-MPC. The lifting model is built to predict the fast rate information of state variables based on the low sampling output. Then, the fast rate control inputs within one sampling interval are solved efficiently with a good tradeoff between computational burden and optimized system performance. The experimental motor drive system tests are carried out to verify the effectiveness of the proposed MRFCS-MPC.
Nanotheranostic agents (NTAs) that integrate diagnostic capabilities and therapeutic functions have great potential for personalized medicine, yet poor tumor specificity severely restricts further ...clinical applications of NTAs. Here, a pro‐NTA (precursor of nanotheranostic agent) activation strategy is reported for in situ NTA synthesis at tumor tissues to enhance the specificity of tumor therapy. This pro‐NTA, also called PBAM, is composed of an MIL‐100 (Fe)‐coated Prussian blue (PB) analogue (K2MnFe(CN)6) with negligible absorption in the near‐infrared region and spatial confinement of Mn2+ ions. In a mildly acidic tumor microenvironment (TME), PBAM can be specifically activated to synthesize the photothermal agent PB nanoparticles, with release of free Mn2+ ions due to the internal fast ion exchange, resulting in the “ON” state of both T1‐weighted magnetic resonance imaging and photoacoustic signals. In addition, the combined Mn2+‐mediated chemodynamic therapy in the TME and PB‐mediated photothermal therapy guarantee a more efficient therapeutic performance compared to monotherapy. In vivo data further show that the pro‐NTA activation strategy could selectively brighten solid tumors and detect invisible lymph node metastases with high specificity.
A metal–organic framework hybrid is designed as a precursor of a nanotheranostic agent (pro‐NTA) to selectively synthesize an NTA with the release of Mn2+ ions in tumor tissues. This pro‐NTA activation strategy provides multimodal diagnosis and tumor treatment with high specificity.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Outsourcing, which has become an important employment strategy, is of increasing interest in both management theory and practice. This paper investigates the determinants of outsourcing from the ...perspective of CEO overconfidence using manually collected outsourcing data from Chinese A-share listed companies for the period 2012-2020. The empirical results show that firms with overconfident CEOs are more likely to adopt outsourcing strategies, and the asset specificity mitigates the positive effect of CEO overconfidence on outsourcing decisions. Furthermore, we find the moderating effect of asset specificity occurs mainly in private firms rather than SOEs and in large firms rather than small firms. Our results indicate inefficiencies associated with overconfidence should be classified as honest mistakes rather than deliberate actions, and strong corporate governance mechanisms help overconfident CEOs avoid making honest mistakes.
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