Methane, an abundant one-carbon(C_(1)) resource, is extensively used in the industrial production of vital fuels and value-added chemicals. However, current industrial methane conversion technologies are energy-and ca...Methane, an abundant one-carbon(C_(1)) resource, is extensively used in the industrial production of vital fuels and value-added chemicals. However, current industrial methane conversion technologies are energy-and carbon-intensive, mainly due to the high activation energy required to break the inert C–H bond, low selectivity, and problematic side reactions, including CO_(2)emissions and coke deposition. Electrochemical conversion of methane(ECM) using intermittent renewable energy offers an attractive solution, due to its modular reactor design and operational flexibility across a broad spectrum of temperatures and pressures. This review emphasizes conversion pathways of methane in various reaction systems, highlighting the significance and advantages of ECM in facilitating a sustainable artificial carbon cycle. This work provides a comprehensive overview of conventional methane activation mechanisms and delineates the complete pathways of methane conversion in electrolysis contexts. Based on surface/interface chemistry, this work systematically analyzes proposed reaction pathways and corresponding strategies to enhance ECM efficiency towards various target products, including syngas, hydrocarbons, oxygenates, and advanced carbon materials. The discussion also encompasses opportunities and challenges for the ECM process, including insights into ECM pathways, rational electrocatalyst design, establishment of benchmarking protocols, electrolyte engineering, enhancement of CH4conversion rates, and minimization of CO_(2)emission.展开更多
The design,manufacturing and DC and microwave characterization of high-power Schottky barrier In Al As/In Ga As back-illuminated mesa structure photodiodes are presented.The photodiodes with 10 and 15μm mesa diameter...The design,manufacturing and DC and microwave characterization of high-power Schottky barrier In Al As/In Ga As back-illuminated mesa structure photodiodes are presented.The photodiodes with 10 and 15μm mesa diameters operate at≥40 and 28 GHz,respectively,have the output RF power as high as 58 m W at a frequency of 20 GHz,the DC responsivity of up to 1.08 A/W depending on the absorbing layer thickness,and a photodiode dark current as low as 0.04 n A.We show that these photodiodes provide an advantage in the amplitude-to-phase conversion factor which makes them suitable for use in highspeed analog transmission lines with stringent requirements for phase noise.展开更多
The investigations of the crystal and magnetic structures of the BaFe12_xAlxO19 （x = 0.1-1.2） solid solutions have been performed with powder neutron diffractometry. Magnetic properties of the BaFe12_xAlxOt9 （x = 0...The investigations of the crystal and magnetic structures of the BaFe12_xAlxO19 （x = 0.1-1.2） solid solutions have been performed with powder neutron diffractometry. Magnetic properties of the BaFe12_xAlxOt9 （x = 0.1-1.2） solid solutions have been measured by vibration sample magnetometry at different temperatures under different magnetic fields. The atomic coordinates and lattice parameters have been Rietveld refined. The invar effect is observed in low temperature range （from 4.2 K to 150 K）. It is explained by the thermal oscillation anharmonicity of atoms. The increase of microstress with decreasing temperature is found from Rietveld refinement. The Curie temperature and the change of total magnetic moment per formula unit are found for all compositions of the BaFet2_xAlxO19 （x = 0.1-1.2） solid solutions. The magnetic structure model is proposed. The most likely reasons and the mechanism of magnetic structure formation are discussed.展开更多
The solid solutions of In^(3+) doped M-type strontium hexaferrites were produced using a conventional solid-state reaction method,and Rietveld analysis of the neutron diffraction patterns was conducted.In^(3+) cations...The solid solutions of In^(3+) doped M-type strontium hexaferrites were produced using a conventional solid-state reaction method,and Rietveld analysis of the neutron diffraction patterns was conducted.In^(3+) cations occupy octahedral (4f_(Ⅵ)and 12 k) and tetrahedral (4f_(Ⅳ)) positions (SG=P6_(3)/mmc(No.194)).The average particle size is 837–650 nm.Curie tempearature (T_(C)) of the compounds monotonically decreased down to~520 K with increasing x.A frustrated magnetic state was detected from ZFC and FC magnetizations.saturation magnetization (M_(s)) and effective magnetocrystalline anisotropy coefficient (k_(eff)) were determined using the law of approach to saturation.A real permittivity (ε″) maximum of~3.3 at~45.5 GHz and an imaginary permittivity (ε′) of~1.6 at~42.3 GHz were observed for x=0.1.A real permeability (μ′) maximum of~1.5 at~36.2 GHz was observed for x=0.Aμ″imaginary permeability maximum of~0.8 at~38.3 GHz was observed for x=0.1.The interpretation of the results is based on the type of dielectric polarization and the natural ferromagnetic resonance features.展开更多
Hexagonal boron nitride(h-BN)nanomaterials are a rising star in the field of biomedicine.This review presents an overview of the progress in h-BN nanomaterials for biological applications.It begins with a general intr...Hexagonal boron nitride(h-BN)nanomaterials are a rising star in the field of biomedicine.This review presents an overview of the progress in h-BN nanomaterials for biological applications.It begins with a general introduction of the structural characteristics of h-BN,followed by the brief introduction of its physical and chemical properties,including thermal,band and mechanical properties,chemical reactivity,biodegradability and biocompatibility,then emphasizes on the recent progress in the biomedical applications including drug delivery,boron neutron capture therapy(BNCT),bioimaging and nanozyme,and ends with the challenges and perspectives related to the biomedical applications.The advantages of BN nanomaterials used for biomedical applications were analyzed,and their problems were also discussed,inspiring the future rational designs of the BN nanomedicines.展开更多
Ships can be operated more efficiently by utilizing intelligent decision support integrated with onboard data collection systems.In this study,a Bayesian optimization-based decision support system,which uti-lizes ship...Ships can be operated more efficiently by utilizing intelligent decision support integrated with onboard data collection systems.In this study,a Bayesian optimization-based decision support system,which uti-lizes ship performance models built by machine learning methods,is proposed to help determine the operational set-points of two engines for double-ended ferries.By optimizing the ferries’power alloca-tion between the stern and bow engines,the Decision Support System(DSS)will simultaneously attempt to keep the ETA of the ferry fixed under a set of operational constraints using the Bayesian optimization.Its objective is to minimize fuel consumption along individual trips.Based on simulation environment,the DSS can reduce at maximum 40%fuel consumption with no significant change of the ETA.Final full-scale experiments of a double-ended ferry demonstrated an average of 15%,where at least half of this saving was achieved by the optimized power allocation between bow and stern engines.展开更多
基金National Key R&D Program of China (2023YFA1508001 and 2023YFA1508002)National Natural Science Foundation of China (22272120 and U2202251)+1 种基金Hainan Province Science and Technology Special Fund(ZDYF2023SHFZ120)Research Foundation of Marine Science and Technology Collaborative Innovation Center of Hainan University (XTCX2022HYB01)。
文摘Methane, an abundant one-carbon(C_(1)) resource, is extensively used in the industrial production of vital fuels and value-added chemicals. However, current industrial methane conversion technologies are energy-and carbon-intensive, mainly due to the high activation energy required to break the inert C–H bond, low selectivity, and problematic side reactions, including CO_(2)emissions and coke deposition. Electrochemical conversion of methane(ECM) using intermittent renewable energy offers an attractive solution, due to its modular reactor design and operational flexibility across a broad spectrum of temperatures and pressures. This review emphasizes conversion pathways of methane in various reaction systems, highlighting the significance and advantages of ECM in facilitating a sustainable artificial carbon cycle. This work provides a comprehensive overview of conventional methane activation mechanisms and delineates the complete pathways of methane conversion in electrolysis contexts. Based on surface/interface chemistry, this work systematically analyzes proposed reaction pathways and corresponding strategies to enhance ECM efficiency towards various target products, including syngas, hydrocarbons, oxygenates, and advanced carbon materials. The discussion also encompasses opportunities and challenges for the ECM process, including insights into ECM pathways, rational electrocatalyst design, establishment of benchmarking protocols, electrolyte engineering, enhancement of CH4conversion rates, and minimization of CO_(2)emission.
基金supported by the Russian Science Foundation(grant number 19-72-30023)。
文摘The design,manufacturing and DC and microwave characterization of high-power Schottky barrier In Al As/In Ga As back-illuminated mesa structure photodiodes are presented.The photodiodes with 10 and 15μm mesa diameters operate at≥40 and 28 GHz,respectively,have the output RF power as high as 58 m W at a frequency of 20 GHz,the DC responsivity of up to 1.08 A/W depending on the absorbing layer thickness,and a photodiode dark current as low as 0.04 n A.We show that these photodiodes provide an advantage in the amplitude-to-phase conversion factor which makes them suitable for use in highspeed analog transmission lines with stringent requirements for phase noise.
基金supported by the Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST“MISiS”(Grant No.K4-2015-040)
文摘The investigations of the crystal and magnetic structures of the BaFe12_xAlxO19 （x = 0.1-1.2） solid solutions have been performed with powder neutron diffractometry. Magnetic properties of the BaFe12_xAlxOt9 （x = 0.1-1.2） solid solutions have been measured by vibration sample magnetometry at different temperatures under different magnetic fields. The atomic coordinates and lattice parameters have been Rietveld refined. The invar effect is observed in low temperature range （from 4.2 K to 150 K）. It is explained by the thermal oscillation anharmonicity of atoms. The increase of microstress with decreasing temperature is found from Rietveld refinement. The Curie temperature and the change of total magnetic moment per formula unit are found for all compositions of the BaFet2_xAlxO19 （x = 0.1-1.2） solid solutions. The magnetic structure model is proposed. The most likely reasons and the mechanism of magnetic structure formation are discussed.
基金conducted with financial support from the Russian Science Foundation (Agreement No. 19-19-00694 of 06 May 2019)。
文摘The solid solutions of In^(3+) doped M-type strontium hexaferrites were produced using a conventional solid-state reaction method,and Rietveld analysis of the neutron diffraction patterns was conducted.In^(3+) cations occupy octahedral (4f_(Ⅵ)and 12 k) and tetrahedral (4f_(Ⅳ)) positions (SG=P6_(3)/mmc(No.194)).The average particle size is 837–650 nm.Curie tempearature (T_(C)) of the compounds monotonically decreased down to~520 K with increasing x.A frustrated magnetic state was detected from ZFC and FC magnetizations.saturation magnetization (M_(s)) and effective magnetocrystalline anisotropy coefficient (k_(eff)) were determined using the law of approach to saturation.A real permittivity (ε″) maximum of~3.3 at~45.5 GHz and an imaginary permittivity (ε′) of~1.6 at~42.3 GHz were observed for x=0.1.A real permeability (μ′) maximum of~1.5 at~36.2 GHz was observed for x=0.Aμ″imaginary permeability maximum of~0.8 at~38.3 GHz was observed for x=0.1.The interpretation of the results is based on the type of dielectric polarization and the natural ferromagnetic resonance features.
基金National Natural Science Foundation of China,Grant/Award Numbers:52272148,21903021Natural Science Foundation of Hunan Province,Grant/Award Number:2022JJ30006Fundamental Research Funds for the Central Universities,Grant/Award Number:531119200114。
文摘Hexagonal boron nitride(h-BN)nanomaterials are a rising star in the field of biomedicine.This review presents an overview of the progress in h-BN nanomaterials for biological applications.It begins with a general introduction of the structural characteristics of h-BN,followed by the brief introduction of its physical and chemical properties,including thermal,band and mechanical properties,chemical reactivity,biodegradability and biocompatibility,then emphasizes on the recent progress in the biomedical applications including drug delivery,boron neutron capture therapy(BNCT),bioimaging and nanozyme,and ends with the challenges and perspectives related to the biomedical applications.The advantages of BN nanomaterials used for biomedical applications were analyzed,and their problems were also discussed,inspiring the future rational designs of the BN nanomedicines.
基金support from the Swedish Foundation for International Cooperation in Research and Higher Education(CH2016–6673).
文摘Ships can be operated more efficiently by utilizing intelligent decision support integrated with onboard data collection systems.In this study,a Bayesian optimization-based decision support system,which uti-lizes ship performance models built by machine learning methods,is proposed to help determine the operational set-points of two engines for double-ended ferries.By optimizing the ferries’power alloca-tion between the stern and bow engines,the Decision Support System(DSS)will simultaneously attempt to keep the ETA of the ferry fixed under a set of operational constraints using the Bayesian optimization.Its objective is to minimize fuel consumption along individual trips.Based on simulation environment,the DSS can reduce at maximum 40%fuel consumption with no significant change of the ETA.Final full-scale experiments of a double-ended ferry demonstrated an average of 15%,where at least half of this saving was achieved by the optimized power allocation between bow and stern engines.
