Electrocatalytic conversion of N 2 to NH 3 via the N 2 reduction reaction (NRR) provides a sustainable avenue for large-scale NH 3 production. However, it remains challenging to develop effective and ...durable NRR catalysts to promote the NH 3 synthesis rate and faradaic efficiency (FE). Here, combining theoretical predictions and experimental verifications, we showed that the CoO nanostructures could be a new class of highly efficient NRR catalysts. Density functional theory calculations revealed that CoO possessed poor HER activity but favorable NRR activity. When supporting CoO quantum dots (QDs, 2–5 nm) on reduced graphene oxide (RGO), the resulting CoO QD/RGO exhibited a high NH 3 yield of 21.5 μg h −1 mg −1 and an FE of 8.3% at −0.6 V vs. the reversible hydrogen electrode under ambient conditions, superior to most of the reported NRR catalysts. Furthermore, the CoO QD/RGO showed excellent selectivity and stability, demonstrating the great potential of Co-based catalysts for electrocatalytic synthesis of NH 3 .
A first‐generation pair of chemiluminescent formaldehyde (FA) probes (CFAP540 and CFAP700) was reported recently. CFAP540 and CFAP700, with high selectivity and sensitivity to FA, are, respectively, ...suitable in cell and in vivo. Experimentalists have confirmed that both probes utilize a general 2‐aza‐Cope FA‐reactive trigger and a chemiluminogenic phenoxydioxetane scaffold. The mechanism and detailed process of CFAP chemiluminescence (CL) remain largely unknown. In the present paper, (time‐dependent) density functional theory calculations are performed on the entire reaction process of CFAP540 with FA to produce CL. The calculations elucidated the CL‐producing process: FA initiates the decomposition of CFAP540 by dehydration condensation, and a phenoxy 1,2‐dioxetane is formed through a series of reactions of aza‐Cope rearrangement, hydrolysis of imine, and β‐elimination of alkoxyl group. Afterwards, the produced phenoxy 1,2‐dioxetane decomposes to produce the m‐oxybenzoate derivative in the first singlet state (S1) via two crossings between potential energy surfaces of the ground state (S0) and S1 state. This m‐oxybenzoate derivative was assigned as the light emitter of the CFAP540 CL. The CL‐producing process and assignment of the light emitter of CFAP700 CL are similar with the corresponding ones of CFAP540. By analyzing the D‐π‐A architecture of the light emitters of CFAP540 and CFAP700, a series of CFAPs is theoretically designed and a scheme to modulate their CL from visible to near‐infrared region is proposed by adjusting the length and structure of the π‐bridge.
Formaldehyde detection: A first‐generation pair of chemiluminescent formaldehyde (FA) probes (CFAP540 and CFAP700) was reported recently. The mechanism and detailed process of CFAP chemiluminescence (CL) remain largely unknown. Thus, (time‐dependent) density functional theory calculations are performed on the entire reaction process of CFAP540 with FA to produce CL. A scheme to develop bright and tunable CFAPs is proposed.
Network virtualization is a key enabler for 5G systems to support the expected use cases of vertical markets. In this context, we study the joint optimal deployment of Virtual Network Functions ...(VNFs) and allocation of computational resources in a hybrid cloud infrastructure by taking the requirements of the 5G services and the characteristics of the cloud architecture into consideration. The resulting mixed-integer problem is reformulated as an integer linear problem, which can be solved by using a standard solver. Our results underline the advantages of a hybrid infrastructure over a standard cloud radio access network consisting only of a central cloud, and show that the proposed mechanism to deploy VNF chains leads to high resource utilization efficiency and large gains in terms of the number of supported VNF chains. To deal with the computational complexity of optimizing a large number of clouds and VNF chains, we propose a simple low-complexity heuristic that attempts to find a feasible VNF deployment solution with a limited number of functional splits. Numerical results indicate that the performance of the proposed heuristic is close to the optimal one when the edge clouds are well dimensioned with respect to the computational requirements of the 5G services.
Long noncoding RNAs (lncRNAs) are emerging as a new class of important regulators of signal transduction in tissue homeostasis and cancer development. Liquid-liquid phase separation (LLPS) occurs in ...a wide range of biological processes, while its role in signal transduction remains largely undeciphered. In this study, we uncovered a lipid-associated lncRNA, small nucleolar RNA host gene 9 (SNHG9) as a tumor-promoting lncRNA driving liquid droplet formation of Large Tumor Suppressor Kinase 1 (LATS1) and inhibiting the Hippo pathway. Mechanistically, SNHG9 and its associated phosphatidic acids (PA) interact with the C-terminal domain of LATS1, promoting LATS1 phase separation and inhibiting LATS1-mediated YAP phosphorylation. Loss of SNHG9 suppresses xenograft breast tumor growth. Clinically, expression of SNHG9 positively correlates with YAP activity and breast cancer progression. Taken together, our results uncover a novel regulatory role of a tumor-promoting lncRNA (i.e., SNHG9) in signal transduction and cancer development by facilitating the LLPS of a signaling kinase (i.e., LATS1).
Antibiotic resistance in bacteria has become a great threat to global public health. Tigecycline is a next‐generation tetracycline that is the final line of defense against severe infections by ...pan‐drug‐resistant bacterial pathogens. Unfortunately, this last‐resort antibiotic has been challenged by the recent emergence of the mobile Tet(X) orthologs that can confer high‐level tigecycline resistance. As it is reviewed here, these novel tetracycline destructases represent a growing threat to the next‐generation tetracyclines, and a basic framework for understanding the molecular epidemiology and resistance mechanisms of them is presented. However, further large‐scale epidemiological and functional studies are urgently needed to better understand the prevalence and dissemination of these newly discovered Tet(X) orthologs among Gram‐negative bacteria in both human and veterinary medicine.
The novel mobile tetracycline‐inactivating enzymes, Tet(X3)–Tet(X5), could confer high‐level tigecycline resistance. They have been disseminated in diverse bacterial hosts from a wide range of ecological niches through promiscuous plasmids and ISCR2. This complex dissemination can be driven by selective pressure from the massive use of the early tetracyclines.
Abstract
Electrorefining process has been widely used to separate and purify metals, but it is limited by deposition potential of the metal itself. Here we report in-situ anodic precipitation (IAP), ...a modified electrorefining process, to purify aluminium from contaminants that are more reactive. During IAP, the target metals that are more cathodic than aluminium are oxidized at the anode and forced to precipitate out in a low oxidation state. This strategy is fundamentally based on different solubilities of target metal chlorides in the NaAlCl
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molten salt rather than deposition potential of metals. The results suggest that IAP is able to efficiently and simply separate components of aluminum alloys with fast kinetics and high recovery yields, and it is also a valuable synthetic approach for metal chlorides in low oxidation states.
Two‐dimensional metal–organic nanosheets (2D MONs) are an emerging class of ultrathin, porous, and crystalline materials. The organic/inorganic hybrid nature offers MONs distinct advantages over ...other inorganic nanosheets in terms of diversity of organic ligands and metal notes. Compared to bulk three‐dimensional metal–organic frameworks, 2D MONs possess merits of high density and readily accessible catalytic sites, reduced diffusion pathways for reactants/products, and fast electron transport. These features endow MONs with enhanced physical/chemical properties and are ideal for heterogeneous catalysis. In this Review, state‐of‐the‐art synthetic methods for the fabrication of 2D MONs were summarized. The advances of 2D MONs‐based materials for electrocatalysis and photocatalysis, including hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), carbon dioxide reduction reaction (CO2RR), and electro‐/photocatalytic organic transformations were systematically discussed. Finally, the challenges and perspectives regarding future design and synthesis of 2D MONs for high‐performance electrocatalysis and photocatalysis were provided.
Thin is everything: Ultrathin two‐dimensional metal–organic nanosheets (2D MONs) are ideal for heterogeneous catalysis, benefiting from their high density and readily accessible catalytic sites, reduced diffusion pathways for reactants/products, and fast electron transport. This Review highlights recent advances of the synthetic methods for 2D MONs and applications in electrocatalysis and photocatalysis.
All-inorganic CsPbX3 (X = Cl, Br or I) perovskite nanocrystals have attracted extensive interest recently due to their exceptional optoelectronic properties. In an effort to improve the charge ...separation and transfer following efficient exciton generation in such nanocrystals, novel functional nanocomposites were synthesized by the in situ growth of CsPbBr3 perovskite nanocrystals on two-dimensional MXene nanosheets. Efficient excited state charge transfer occurs between CsPbBr3 NCs and MXene nanosheets, as indicated by significant photoluminescence (PL) quenching and much shorter PL decay lifetimes compared with pure CsPbBr3 NCs. The as-obtained CsPbBr3/MXene nanocomposites demonstrated increased photocurrent generation in response to visible light and X-ray illumination, attesting to the potential application of these heterostructure nanocomposites for photoelectric detection. The efficient charge transfer also renders the CsPbBr3/MXene nanocomposite an active photocatalyst for the reduction of CO2 to CO and CH4. This work provides a guide for exploration of perovskite materials in next-generation optoelectronics, such as photoelectric detectors or photocatalyst.
This paper considers a reconfigurable intelligent surface (RIS)-aided millimeter wave (mmWave) downlink communication system where hybrid analog-digital beamforming is employed at the base station ...(BS). We formulate a power minimization problem by jointly optimizing hybrid beamforming at the BS and the response matrix at the RIS, under the signal-to-interference-plus-noise ratio (SINR) constraints at all users. The problem is highly challenging to solve due to the non-convex SINR constraints as well as the unit-modulus phase shift constraints for both the RIS reflection coefficients and the analog beamformer. A two-layer penalty-based algorithm is proposed to decouple variables in SINR constraints, and manifold optimization is adopted to handle the non-convex unit-modulus constraints. We also propose a low-complexity sequential optimization method, which optimizes the RIS reflection coefficients, the analog beamformer, and the digital beamformer sequentially without iteration. Furthermore, the relationship between the power minimization problem and the max-min fairness (MMF) problem is discussed. Simulation results show that the proposed penalty-based algorithm outperforms the state-of-the-art semidefinite relaxation (SDR)-based algorithm. Results also demonstrate that the RIS plays an important role in the power reduction.
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