[en] Highlights: • The Ag loaded Bi_3NbO_7 photocatalyst (Ag/Bi_3NbO_7) was prepared by co-precipitation and photo-reduction methods. • The degradation rate constant over Ag/Bi_3NbO_7 with Ag loading of 2 wt% was 7.81 times that of bulk Bi_3NbO_7 catalyst. • The photocatalytic mechanism was proposed. - Abstract: A nanostructured Ag loaded Bi_3NbO_7 photocatalyst was synthesized by the co-precipitation combined with photodeposition method, and characterized by XRD, XPS, SEM, BET nitrogen adsorption–desorption, and UV–vis DRS. Photocatalytic activities of the Ag/Bi_3NbO_7 samples were evaluated by the degradation of methyl orange under visible light irradiation. It was shown that the best photocatalytic activity was obtained on sample with Ag loading level of 2 wt%. It was suggested that the increase in photocatalytic activity of Ag/Bi_3NbO_7 photocatalyst was explained on the basis of the electron trapping ability, the electron exciting ability and the surface plasmon resonance effect of metallic Ag particles

[en] The factors affecting the uncertainty of the measurement results of γ knife therapy source radiation output rate are introduced, the influence and contribution of different factors to the uncertainty of the measurement results are described and analyzed. The results show that the expanded uncertainty of the measured radiation output rate is 3.62%. The measurement results of the same set of γ knife therapy sources radiation output rate were compared and verified. The results of the two measurements were consistent, which further verified the accuracy, stability and reliability of the measurement system. (authors)

[en] Adsorption of Pb"2"+ ion by a tartrate intercalated MgAl layered double hydroxides (MgAl-TA LDHs) was studied. The adsorption isotherms and kinetics were investigated as a function of various experimental parameters using batch adsorption experiments. The results indicated that the adsorption isotherm was well described by Sips model. The kinetic adsorption data were fitted well to the pseudo-second-order kinetic equation. The adsorption of Pb"2"+ was controlled mainly by the chemical process combined with intraparticle diffusion. Parameters of adsorption thermodynamic suggested that the interaction of Pb"2"+ adsorbed by MgAl-TA LDHs adsorbents was thermodynamically spontaneous and endothermic.

[en] l-Tryptophan-capped carbon quantum dots (l-CQDs) were facilely synthesized through “green” methodology, and the obtained material was utilized as a sensitive and selective fluorescence sensor for mercury ion (Hg"2"+) in pure aqueous solutions. Carboxyl-functionalized CQDs were first green synthesized by a one-step hydrothermal route, and l-tryptophan was then attached to CQDs via direct surface condensation reaction in aqueous solution at room temperature. The as-synthesized l-CQDs had an average size of ca. 5 nm with a good dispersity in water, and exhibited a favorable selectivity for Hg"2"+ ions over a range of other common metal cations in aqueous solution (10 mM PBS buffer, pH 6.0). Upon the addition of Hg"2"+, a complete fluorescence quenching (ON–OFF switching) of l-CQDs was evident from the fluorescence titration experiment, and the fluorescence detection limit of Hg"2"+ was calculated to be 11 nM, which indicated that the obtained environmentally friendly l-CQDs had sensitive detection capacity for Hg"2"+ in aqueous solution.

[en] Li₄Ti₅O₁₂/Ag composite nanobelts with an average width of ca. 1.12 μm were successfully synthesized via a facile electrospinning, and the average width is ca. 1.12 μm. The Li₄Ti₅O₁₂/Ag composites show perfect initial discharge capacity (178.72 mA h g^–1 at 0.1 C), better rate capability (131.70 mA h g^–1 after cycled at 15 C) and super cycling stability (172.21 mA h g^–1 after 100 cycles at 0.2 C) compared to pure Li₄Ti₅O₁₂ nanobelts when used as anode materials for lithium ion batteries. The excellent electrochemical performance is explained by the nanostructure of obtained samples which could provide an effective ion and electron transport in the longitudinal direction. The addition of Ag could enhance charge transfer due to increased electronic conductivity. Our new findings provide an effective way to improve the electrochemical performance of Li₄Ti₅O₁₂ anode materials for lithium ion batteries.

[en] Highlights: • N doping is obtained by adding PPy. • Ni⁰ can be determined by partial sulfurization and Ar / H₂ treatment. • The Ni₃S₂/Ni@N-doped C electrode showed excellent performances for alkaline metal batteries. -- Abstract: While lithium-ion batteries (LIBs) have been widely used in commercial devices, finding suitable anode materials for alkali metal batteries is still challenging. Therefore, Ni₃S₂/Ni@N-doped carbon composite electrode was fabricated as the anode for alkali metal batteries. It was found that the Ni₃S₂/Ni@N-doped carbon electrode achieved a capacity of 742 mAh g⁻¹ at the 1500th cycle at the current density of 1000 mA g⁻¹ for LIBs, and obtained 275 mAh g⁻¹ at the 250th cycle during 500 mA g⁻¹ for Na⁺ storage. Moreover, it showed 52 mAh g⁻¹ after 50 cycles at 100 mA g⁻¹ for K⁺ storage. The excellent performances of this electrode is likely due to the combined effect of Ni and C layer. This work provides a simple approach approach for the design of high-performance materials that can be applied to commercial production as a potential substitute for the current alkali ion battery anodes.

[en] This paper firstly determines the main factors affecting its the efficiency of multi-injection electron beam introduction and preliminary structural parameters through theoretical analysis. Secondly, the Ka-band relativistic multi-beam diode model is established by three-dimensional particle simulation software to optimize the structural parameters. The final efficiency of electron beam introduction can reach 89%. An experimental study on the generation and transmission of electron beams was carried out to verify the results of particle simulation. Under the condition of electron beam voltage 502 kV, beam current 4.34 kA, axial magnetic induction strength 0.76 T, the electron beam introduction efficiency reached 72%. The electron beam pattern obtained by electron beam bombardment of the nylon target indicates that the shape of the electron beam is not distorted during generation and transmission. The generated electron beam diameter is about 2 mm. The simulation and experimental results show that the designed high-current multi-beam diode can generate high-quality electron beams and achieve efficient electron beam introduction. (authors)

[en] In order to explore the miniaturized relativistic klystron amplifier (RKA), we develop the theoretical analysis and simulation on the periodic permanent magnet (PPM) of the coaxial RKA. The Halbach arrays are applied to this PPM system and generate periodic cusped magnetic field. We evaluate the radial and axial components of the PPM field and present the characteristics of the magnetic distribution. Based on our expressions of the magnetic distribution, we get the transmission stability condition of the annular IREB in the PPM system for the coaxial waveguide. According to the stability condition, we design and optimize a PPM system for a Ka band coaxial RKA. Then the optimized period and amplitude of the PPM system are obtained. The results of the research show that the PPM system can focus the electron beam with voltage of 500 kV and current of 6 kA in the Ka band coaxial RKA, while the period and amplitude of the PPM system are 18 mm, 0.33 T, respectively. In addition, the coaxial RKA can stably generate millimeter wave with power of 1 GW. In a word, it is possible that the PPM system can be applied to the high power coaxial RKA. (authors)

[en] In this study, Mn-doped MgAl-layered double hydroxides (LDHs) were successfully synthesized for efficient removal arsenate from aqueous solution. The structure and composition of Mn-doped MgAl-LDHs intercalated by different ions such as CO₃²⁻, Cl⁻, or NO₃⁻ were investigated. The characterizations of XRD, ATR FT-IR, SEM, TG-DTA, and N₂ adsorption-desorption presented that the Mn-doped MgAl-LDHs (donated as Mn-LDHs) have very similar physical morphologies and properties to the MgAl-Cl-LDHs (donated as Mg-LDHs). However, the Mn-LDHs exhibits more preferable arsenate adsorption than Mg-LDHs. The As(V) removal kinetics data of Mn-LDHs is followed pseudo-second-order expression. The adsorption capacity of As(V) on Mn-LDHs via Langmuir isotherm model was 166.94 mg g⁻¹. The results of XPS revealed that the enhanced removal mechanism can be attributed to surface complexation of As(V) with Mn on the surface of Mn-LDHs. These results prove that Mn-doped LDHs can be considered as a potential material for adsorption As(V) from wastewater.