Facile construction of composition-tuned ruthenium-nickel nanoparticles on g-C3N4 for enhanced hydrolysis of ammonia borane without base additives

Developing high-efficiency and low-cost catalysts for hydrogen evolution from hydrolysis of ammonia borane (AB) is significant and critical for the exploitation and utilization of hydrogen energy. Herein, the in-situ fabrication of well-dispersed and small bimetallic RuNi alloy nanoparticles (NPs) with tuned compositions and concomitant hydrolysis of AB are successfully achieved by using graphitic carbon nitride (g-C₃N₄) as a NP support without additional stabilizing ligands. The optimized Ru₁Ni_7.5/g-C₃N₄ catalyst exhibits an excellent catalytic activity with a high turnover frequency of 901 min^?1 and an activation energy of 28.46 kJ mol^?1 without any base additives, overtaking the activities of many previously reported catalysts for AB hydrolysis. The kinetic studies indicate that the AB hydrolysis over Ru₁Ni_7.5/g-C₃N₄ is first-order and zero-order reactions with respect to the catalyst and AB concentrations, respectively. Ru₁Ni_7.5/g-C₃N₄ has a good recyclability with 46% of the initial catalytic activity retained even after five runs. The high performance of Ru₁Ni_7.5/g-C₃N₄ should be assigned to the small-sized alloy NPs with abundant accessible active sites and the synergistic effect between the composition-tuned Ru–Ni bimetals. This work highlights a potentially powerful and simple strategy for preparing highly active bimetallic alloy catalysts for AB hydrolysis to generate hydrogen.     

Combination of vegetable soup and glucan demonstrates synergistic effects on macrophage-mediated immune responses

Vegetable soup (VS), a plant-based functional food, has been used as a traditional folk medicine and is attracting attention for its ability to enhance the immune response. β-Glucan, a well-established and effective immunomodulator, has synergistic effects when used in combination with some bioactive compounds. In the present study, we aimed to evaluate the synergistic immunomodulatory effects of the combination of VS and β-glucan on macrophage-mediated immune responses. β-Glucan was demonstrated to synergistically enhance the VS-stimulated immune response, including the production of interleukin-6, tumor necrosis factor-α, and nitric oxide, mainly through the mitogen-activated protein kinase pathway in macrophages. In addition, this combination has the potential for further development in functional foods with immune-enhancing activity.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10068-021-00888-x.     

贵州北盘江增殖放流效果评价

为了评估北盘江鱼类增殖放流效果,2017~2018年期间采用体外荧光、剪鳍、"T"型标三种标志方法对目标鱼类进行标志放流,通过集中捕捞方式进行回捕调查,集中捕捞时间为2017年7月、2018年8月,捕捞水域为董菁-马马崖-光照-善泥坡库区。结果表明,白甲鱼回捕率较高,为0.82%,其他鱼类均在0.5%左右,其中主要为低龄鱼类,高龄鱼类较少;董菁打邦河及各库尾水域物种丰富度较高,善泥坡高家渡码头和马马崖库区试验库尾物种多样性指数相对较低。建议在以后的增殖放流活动中,加大每年的监测频次。     

Correlation among hydrogenation,magnetoelastic coupling,magnetic anisotropy,and magnetoresistance in magnetostrictive,hydrogen-absorbing palladium-cobalt alloy films for hydrogen sensing

Hydrogen-absorbing magnetic alloy films, such as palladium-cobalt (PdCo) alloy films, are expected to play a significant role in the next generation of hydrogen sensors. However, effects of hydrogenation on such films are very complex, since these alloys show strong spin-orbit interaction, i.e., strong magnetoelastic coupling. Accordingly, we conducted integrated research on the hydrogenation, magnetoelastic coupling, magnetism, and galvanomagnetic effect of PdCo alloy films having different magnetic anisotropies of longitudinal and perpendicular magnetic anisotropies. As a result, it was revealed that the stress in the film determines its magnetic anisotropy. The magnetoresistance curves of films, consisting of ordinal and anisotropic magnetoresistance effects, correspond well to the magnetization-magnetic field curves. Hydrogenation results in the compressive stress and decreased magnetostriction, which both have a negative influence on the perpendicular magnetic anisotropy energy of the films. Moreover, the influence is observed also in ordinal and anisotropic magnetoresistances. In addition, the increases in coercivity and electronic resistivity due to the incorporated hydrogen atoms (and related defects) are detected. The results are summarized in a correlation diagram, which shows that hydrogen-absorbing magnetic alloy films are very suitable for use in hydrogen sensors—the films can detect hydrogen via various methods such as magnetic anisotropy, galvanomagnetic effect, coercivity, and resistivity.     

A new perspective of co-doping and Nd segregation effect on proton stability and transportation in Y and Nd co-doped BaCeO3

Bulk and surface properties of proton stability and transportation in Y and Nd co-doped BaCeO₃ (BCYN), especially the effect of Nd segregation, were investigated by first-principles calculations. Since the structure of doped BaCeO₃ at the operating temperature of proton-conducting has been unclear for a long time, we have summarized the latest experimental results and calculated the structure of the asymmetric BCYN for the first time. The results show that compared with Y, Nd doping promotes oxygen vacancy formation, however reduces proton stability. Our calculation can also provide a possible explanation for the formation of space charge layer at the grain boundary of doped BaCeO₃ in experiment. Unlike the stable Y in BCYN, Nd is calculated to be easily segregated, which can facilitate both proton hydration and proton transportation near the surface. Moreover, Nd segregation at the grain boundary is predicted to be beneficial for proton transportation between grains.     

Theoretical investigation of solvent effects on the selective hydrogenation of furfural over Pt(111)

It was well known that solvent effect plays a very important role in the catalytic reaction. There are many theoretical studies on the solvent effect in homogeneous catalysis while there are few theoretical studies on the solvent effect in the heterogeneous catalytic reaction and there has been no work to investigate the solvent effect on furfural transformation in heterogeneous catalysis. In the present work, both the density functional calculations and the microkinetic analysis were performed to study the selective hydrogenation of furfural over Pt(111) in the presence of methanol as well as toluene and compared with that in the gas condition. The present results indicated that the methanol can enhance the adsorption strength of furfural and other oxygen-containing reaction species due to its relatively strong polarity properties and this can be a main reason for solvent-induced high activity and selectivity. Another reason is that reaction paths study showed that the presence of methanol solvent makes the dehydrogenation of furfural less thermochemical due to the fact that furfural is more stabilized than that of dehydrogenation species, and methanol also has an inhibition effect on the dehydrogenation of furfural in the kinetic aspect, and further energetic span theory proves highest activity and selectivity for hydrogenation in methanol solvent of vapor, methanol and toluene. Moreover, microkinetic model simulation demonstrated that the activity and selectivity of hydrogenation in methanol is both higher than that in vapor and toluene. The much higher activity in methanol is due to the stabilized adsorbed reactants in the surface, which leads to a higher surface coverage of furfural. It might be proposed based on the present work that a solvent with relatively strong polarity may be favorable for the high selective hydrogenation of furfural.     

Large electrocaloric effect in two-step-SPS processed Pb(Sc0.25In0.25Nb0.25Ta0.25)O3 medium-entropy ceramics

Ferroelectric ceramic with a large electrocaloric (EC) effect at a very low electric field is very attractive in the next solid state refrigeration technology. In this work, two Pb(Sc_0.25In_0.25Nb_0.25Ta_0.25)O₃ (PSINT) medium-entropy ceramics were successfully synthesized by a spark plasma sintering (SPS) technology, including one-step-SPS processed and two-step-SPS processed samples. A large EC effect (△T ～ 0.85 K) with a high EC strength (△T/△E ～ 0.021 K cm/kV) around room temperature are obtained at a very low electric field (～40 kV/cm) in the two-step-SPS processed sample. Moreover, the working temperature range is very broad (～120 K), which can be responsible for the high relaxation degree of the dielectric peak. It can be believed that the PSINT medium-entropy ceramics can be promising candidates for application in the next-generation EC cooling devices.     

Synergistic effect of binary fluoride sintering additives on the properties of silicon nitride ceramics

A variety of combinations of YF₃ and MgF₂ were used as sintering aids in the fabrication of Si₃N₄ ceramics via gas pressure sintering (GPS). The synergistic effects of YF₃ and MgF₂ on the liquid viscosity, mechanical properties, thermal conductivities, and grain growth kinetics of the Si₃N₄ ceramics were investigated. The results showed that appropriately adjusting the YF₃/MgF₂ ratio could decrease liquid viscosity, reducing the diffusion energy barrier of the solute atom and promoting mass transfer. Meanwhile, the chemical bonding strength in the grain boundary complexions formed by the metal cations also influenced grain boundary migration. Samples doped with 4 mol% YF₃ and 2 mol% MgF₂ achieved the lowest grain growth exponent (n = 2.9) and growth activation energy (Q = 616.7 ± 16.5 kJ mol^?1) as well as the highest thermal conductivity (83 W m^?1 K^?1) and fracture toughness (8.82 ± 0.13 MPa m^1/2).