In this paper, we propose a new interference-suppression beamformer design and a Direction-of-Arrival (DoA) estimation method for Line-of-Sight (LoS) multi-user communication systems with circular ...Large Intelligent Surfaces (LISs). This symmetrical circular-shaped LIS allows signals defined on it to be formed by combining Fourier and Bessel series. The Fourier harmonics are orthogonal along the rotational direction and the Bessel functions constituting the Bessel series are orthogonal along the radial direction. Synthesizing basis functions from these two series results in the proposed interference-suppression beamformer, with their coefficients designed to cancel inter-user interference. Also by exploiting signal structure of a circular LIS communicating with Mobile Stations (MSs), we devise a DoA estimation method to obtain directional information of incoming signals. Under LoS channel, the DoA corresponds to elevation and Azimuth angles of MSs relative to the LIS. This method is numerically demonstrated to have promising performance with high-frequency carriers.
Electrochemical reduction of carbon dioxide (CO2) is substantially researched due to its potential for storing intermittent renewable electricity and simultaneously helping mitigating the pressing ...CO2 emission concerns. The major challenge of electrochemical CO2 reduction lies on having good controls of this reaction due to its complicated reaction networks and its unusual sensitivity to the dynamic changes of the catalyst structure (chemical states, compositions, facets and morphology, etc.), and to the non‐catalyst components at the electrode/electrolyte interface, in another word the reaction environments. To date, a comprehensive analysis on the interplays between the above catalyst‐dynamic‐changes/reaction environments and the CO2 reduction performance is rare, if not none. In this review, the catalyst dynamic changes observed during the catalysis are discussed based on the recent reports of electrochemical CO2 reduction. Then, the above dynamic changes are correlated to their effects on the catalytic performance. The influences of the reaction environments on the performance of CO2 reduction are also discussed. Finally, some perspectives on future investigations are offered with the aim of understanding the origins of the effects from the catalyst dynamic changes and the reaction environments, which will allow one to better control the CO2 reduction toward the desired products.
This review focus on understanding the origin of the dynamic changes at the catalyst–electrolyte interface, and uncovering the interplays between these changes and the CO2 reduction performance, the obtained insights can guide the design of catalysts and reactors for the efficient electrochemical CO2 reduction.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Abstract
Developing active single-atom-catalyst (SAC) for alkaline hydrogen evolution reaction (HER) is a promising solution to lower the green hydrogen cost. However, the correlations are not clear ...between the chemical environments around the active-sites and their desired catalytic activity. Here we study a group of SACs prepared by anchoring platinum atoms on NiFe-layered-double-hydroxide. While maintaining the homogeneity of the Pt-SACs, various axial ligands (−F, −Cl, −Br, −I, −OH) are employed
via
a facile irradiation-impregnation procedure, enabling us to discover definite chemical-environments/performance correlations. Owing to its high first-electron-affinity, chloride chelated Pt-SAC exhibits optimized bindings with hydrogen and hydroxide, which favor the sluggish water dissociation and further promote the alkaline HER. Specifically, it shows high mass-activity of 30.6 A mgPt
−1
and turnover frequency of 30.3 H
2
s
−1
at 100 mV overpotential, which are significantly higher than those of the state-of-the-art Pt-SACs and commercial Pt/C catalyst. Moreover, high energy efficiency of 80% is obtained for the alkaline water electrolyser assembled using the above catalyst under practical-relevant conditions.
Metal–organic frameworks (MOFs) and MOF‐derived nanostructures are recently emerging as promising catalysts for electrocatalysis applications. Herein, 2D MOFs nanosheets decorated with Fe‐MOF ...nanoparticles are synthesized and evaluated as the catalysts for water oxidation catalysis in alkaline medium. A dramatic enhancement of the catalytic activity is demonstrated by introduction of electrochemically inert Fe‐MOF nanoparticles onto active 2D MOFs nanosheets. In the case of active Ni‐MOF nanosheets (Ni‐MOF@Fe‐MOF), the overpotential is 265 mV to reach a current density of 10 mA cm−2 in 1 m KOH, which is lowered by ≈100 mV after hybridization due to the 2D nanosheet morphology and the synergistic effect between Ni active centers and Fe species. Similar performance improvement is also successfully demonstrated in the active NiCo‐MOF nanosheets. More importantly, the real catalytic active species in the hybrid Ni‐MOF@Fe‐MOF catalyst are unraveled. It is found that, NiO nanograins (≈5 nm) are formed in situ during oxygen evolution reaction (OER) process and act as OER active centers as well as building blocks of the porous nanosheet catalysts. These findings provide new insights into understanding MOF‐based catalysts for water oxidation catalysis, and also shed light on designing highly efficient MOF‐derived nanostructures for electrocatalysis.
A highly efficient 2D metal–organic frameworks (MOF)‐based hybrid electrocatalyst for the oxygen evolution reaction (OER) is demonstrated by in situ deposition of electrochemically inert Fe‐MOF nanoparticles onto the active Ni‐MOF nanosheets. This work provides new insights into understanding MOF‐based catalysts for water oxidation catalysis, and sheds light on developing MOF‐derived nanostructures for electrocatalysis.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Core/shell structured metal halide perovskite nanocrystals (NCs) are emerging as a type of material with remarkable optical and electronic properties. Research into this field has been developing and ...expanding rapidly in recent years, with significant advances in the studies of the shell growth mechanism and in understanding of properties of these materials. Significant enhancement of both the stability and the optical performance of core/shell perovskite NCs are of particular importance for their applications in optoelectronic technologies. In this review, the recent advances in core/shell structured perovskite NCs are summarized. The band structures and configurations of core/shell perovskite NCs are elaborated, the shell classification and shell engineering approaches, such as perovskites and their derivative shells, semiconductor shell, oxide shell, polymer shell, etc. are reviewed, and the shell growth mechanisms are discussed. The prospective of these NCs in lighting and displays, solar cells, photodetectors, and other devices is discussed in the light of current knowledge, remaining challenges, and future opportunities.
Core/shell metal halide perovskite nanocrystals show enhanced stability and optical properties, which are beneficial for their applications in lighting and displays, solar cells, photodetectors, lasing, photocatalysis, and biomedical imaging. In this review, recent advances in synthetic strategies and shell growth of core/shell nanocrystals are reviewed, and their enhanced material properties and emerging applications are discussed.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The occurrence of 15 antibiotics in soil and manure samples from 11 large-scale greenhouse vegetable production (GVP) bases in Beijing, China was investigated. Results showed that the greenhouse ...soils were ubiquitously contaminated with antibiotics, and that antibiotic concentrations were significantly higher in greenhouses than in open field soils. The mean concentrations of four antibiotic classes decreased in the following order: tetracyclines (102μg/kg)>quinolones (86μg/kg)>sulfonamides (1.1μg/kg)>macrolides (0.62μg/kg). This investigation also indicated that fertilization with manure and especially animal feces might be the primary source of antibiotics. A risk assessment based on the calculated risk quotients (RQs) demonstrated that oxytetracycline, chlortetracycline, norfloxacin, ciprofloxacin and enrofloxacin could pose a high risk to soil organisms. These results suggested that the ecological effects of antibiotic contamination in GVP bases and their potential adverse risks on human health need to be given special attention.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Highly active and durable electrocatalysts for the oxygen evolution reaction (OER) is greatly desired. Iridium oxide/graphitic carbon nitride (IrO2/GCN) heterostructures are designed with ...low‐coordinate IrO2 nanoparticles (NPs) confined on superhydrophilic highly stable GCN nanosheets for efficient acidic OER. The GCN nanosheets not only ensure the homogeneous distribution and confinement of IrO2 NPs but also endows the heterostructured catalyst system with a superhydrophilic surface, which can maximize the exposure of active sites and promotes mass diffusion. The coordination number of Ir atoms is decreased owing to the strong interaction between IrO2 and GCN, leading to lattice strain and increment of electron density around Ir sites and hence modulating the attachment between the catalyst and reaction intermediates. The optimized IrO2/GCN heterostructure delivers not only by far the highest mass activity among the reported IrO2‐based catalysts but also decent durability.
IrO2/GCN (iridium oxide/graphitic carbon nitride) heterostructures with abundant low‐coordinated Ir sites and superhydrophilic surfaces are designed toward fast and durable oxygen evolution. The results present an effective GCN‐based heterostructure engineering strategy for developing highly active electrocatalysts.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Moral education in colleges and universities is an important part of the talent training system, including moral education curriculum, moral education practice, mental health education. Volunteer ...service is a public welfare act in which volunteers volunteer their time, knowledge, property, technology, with the ultimate goal of helping others and serving the society without personal compensation. As an innovative form of moral education practice in colleges and universities, college students' voluntary service is of great significance in promoting the reform and innovation of moral education, enhancing the affinity, appeal and influence of moral education, and building a positive psychology for college students.
As an effective carrier of moral education practice in colleges and universities, voluntary service is helpful to enhance the effectiveness of moral education practice and construct the positive psychology of college students. This project is based on the actual situation of college students participating in volunteer services, and collected the volunteer services of 4545 college students in Zhejiang Province. Through model construction and data modeling, the correlation between college students' participation in volunteer service and their moral education performance and mental health was analyzed, and the basic path and guarantee measures to promote the role of volunteer service in moral education and positive psychological construction were deeply explored.
From the correlation analysis of students' voluntary service participation, moral education performance and voluntary service motivation, students' attributes are determined according to their voluntary service participation, so as to predict their moral education performance and mental health level.
College students' voluntary service is partially positively related to their moral education performance and mental health. In order to improve students' moral education performance and mental health, we can optimize the participation frequency, participation duration, participation ways and type structure of voluntary service, constantly increase the participation frequency of voluntary service, increase the duration of voluntary service, broaden the participation ways of voluntary activities, and enrich the types of voluntary service activities.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Pitaya (Hylocereus spp.) is a member of the cactus family that is native to Central and South America but is now cultivated throughout the sub-tropical and tropical regions of the world. It is of ...great importance due to its nutritional, ornamental, coloring, medicinal, industrial, and high consumption values. In order to effectively utilize and develop the available genetic resources, it is necessary to appreciate and understand studies pertaining to the usage, origin, nutrition, diversity, evaluation, characterization, conservation, taxonomy, and systematics of the genus Hylocereus. Additionally, to gain a basic understanding of the biology of the plant, this review has also discussed how biotechnological tools, such as cell and tissue culture, micropropagation (i.e., somatic embryogenesis, organogenesis, somaclonal variation, mutagenesis, androgenesis, gynogenesis, and altered ploidy), virus-induced gene silencing, and molecular marker technology, have been used to enhance pitaya germplasm.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Motivated by energy shortages and in view of current efforts to develop clean, renewable energy sources based on fusion, a solar‐driven strategy has been developed for deuterium evolution. Deuterium ...is a critical resource for many aspects. However, the limited natural abundance of deuterium and the complexity of established technologies, such as quantum sieving (QS) for deuterium production under extreme conditions, pose challenges. The new method has the potential for robust and sustainable deuterium evolution, enabling deuterium production at a high rate of 9.745 mmol g−1 h−1. The activity, thermodynamic, and kinetic characteristics are also investigated and compared between photocatalytic heavy water (D2O) splitting and water (H2O) splitting. This study opens a new avenue to discover promising photocatalytic deuterium generation systems for advanced solar energy utilization and deuterium enrichment.
D‐lightful: A conceptual breakthrough for the combination of efficient deuterium production and recycling of contaminated D2O by solar‐driven photocatalytic strategy. The new method has the potential for robust and sustainable deuterium evolution, enabling deuterium production at a high rate of 9.745 mmol g−1 h−1.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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