[en] Highlights: • Ag_3PO_4 nanoparticles decorated with graphite-like carbon nitride material (g-C_3N_4). • Synthesized by a template-free in situ precipitation method. • Excellent (7 times higher) photooxidation ability. • Much more stable than pure Ag_3PO_4 in the photodegradation process. • Formation of heterojunction between Ag_3PO_4 and g-C_3N_4 contributed to the separation efficiency. - Abstract: The method of decorating Ag_3PO_4 nanoparticles with carbon nitride material (g-C_3N_4) is demonstrated as an efficient pathway to remarkably improve the stability and photocatalytic performance of Ag_3PO_4 nanoparticles which have been widely used in photocatalysis, but limited by the instability. The improved material herein results in the largely enhanced photocatalytic performance for water purification under visible light irradiation, which was nearly 7 times as high as that of pure Ag_3PO_4. Meanwhile, the as-obtained materials show the unique stable property, mainly contributed by the protection effect of decorated g-C_3N_4 sheet. Additionally, the radical trapping experiments revealed that the introduction of g-C_3N_4 transformed the photocatalytic mechanism to some degree, where ·O_2"− played a more important role. The tremendous enhancement in catalytic performance may be attributed to the larger surface area, controllable particle size and the synergistic effect between Ag_3PO_4 and g-C_3N_4, promoting the separation efficiency of the photogenerated electron-hole pairs. The decorating system can in principle be broadly put into use for unstable photocatalysts.

[en] Improvement of the environmental pressure of gas bearing can enhance the load capacity of dynamic gas bearing. This study analyzes the effect of environmental pressure on the dynamic characteristics of a bump foil gas aerodynamic bearing. Results show that an increase in the environmental pressure enhances the direct dynamic stiffness Kxx and Kyy and the direct dynamic damping Dxx and Dyy of gas film. The direct stiffness Kxx and Kyy and direct damping Dxx and Dyy of gas film increase with the increase of the environmental pressure of gas bearing. The load capacity of bearing is related to the direct stiffness of gas film. Therefore, the direct stiffness Kyy can be increased by increasing the environmental pressure of gas bearing, consequently improving the load capacity of the bearing. (paper)

[en] Magnetic compensated materials attracted much interests due to the observed large exchange bias and large coercivity, and also their potential applications in the antiferromagnetic spintronics with merit of no stray field. In this work, by using ab-initio studies, we designed several Ni (Pd, Pt) doped Mn₃Ge-based D0₂₂-type tetragonal Heusler alloys with fully compensated states. Theoretically, we find the total moment change is asymmetric across the compensation point (at ~x=0.3) in Mn_3-xY_xGe (Y=Ni, Pd, Pt). In addition, an uncommon discontinuous jump is observed across the critical zero-moment point, indicating that some non-trivial properties may emerge at this point. Further electronic analyses of these compensated alloys reveal high spin polarizations at the Fermi level, which is advantageous for spin transfer torque applications. - Highlights: • Several new fully compensated magnetic states are identified in Mn₃Ge-based tetragonal alloys. • The magnetic moment changes are asymmetric upon Ni, Pd and Pt substitution. • Discontinuous jumps exist across the compensated points. • The three compensated alloys possess large spin polarizations.

[en] The transient thermal hydraulic characteristics of 49-2 Swimming Pool Reactor (SPR) were analyzed by RELAP5/MOD3.3 code to verify the capability of natural circulation and minus reactivity feedback for accident mitigation under the condition of station blackout (SBO). Then, the effects on accident consequence and sequence for core channels and primary pumps were briefly discussed. The calculation results show that the reactor can be shutdown by the effect of minus reactivity feedback, and the residual heat can be removed through the stable natural circulation. Therefore, it demonstrates that the 49-2 SPR is safe during the accident of SBO. (authors)

[en] The effect of radial position of gas holes in the distributor on the performance of cylindrical Hall thruster was investigated. A series of gas distributors with different radial positions (R_g) of holes were designed in the experiment. The results show that the larger R_g leads to the higher ion current and electron current; meanwhile, the beam angle in plume is narrowed. Nevertheless, the peak energy in ion energy distribution function increases, together with the narrowing of ion energy distribution function. As a result, the overall performance is enhanced. It is suggested that the growing of R_g could lead to the movement of the main ionization region towards anode, which could promote ion velocity and the clearer separation of acceleration region from ionization region. This work can provide some optimal design ideas to improve the performance of the thruster.

[en] The performance characteristics of a cylindrical Hall thruster depending on the magnetic field near the anode were investigated. The magnetic shielding rings were designed to adjust the magnetic field near the anode in different levels. The experiment results show that decreasing the magnetic field near the anode contributes to the enhancement of propellant utilization and the narrowing of ion energy distribution. It is suggested that the ionization region extends towards the anode, meanwhile, the angular distribution of ion beam is narrower, which could be attributed to the growing azimuthal current. As a result, the thrust and efficiency are enhanced significantly. This work can provide some optimal design ideas of the magnetic field to improve the performance of the thruster. (paper)

[en] A novel broad area slotted Fabry—Perot diode laser is designed and fabricated. Using a new semi-analytical method, we introduce effective refractive index perturbations in the form of etched slot features into a conventional 980 nm broad area Fabry—Perot cavity, and the spectral characteristics of the device are expected to be noticeably improved. A low density of slot features is formed by using standard optical lithography and inductively coupled plasma dry etching. The experimental results show that the full spectral width at half-maximum is less than 0.4 nm, meanwhile, the thermal shift of the emission spectrum is decreased from 0.26 to 0.07 nm/°C over a temperature range of 10 to 60 °C. The improved spectral characteristics of the device are proved to be attributed to such slotted Fabry—Perot laser structures. (semiconductor devices)

[en] Highlights: • The water usage for hydrogen production from biomass and coal was explored. • The uncertainty analysis was carried out for water consumption of hydrogen production process. • The influence of major factors on total water consumption was demonstrated. • Constructive measures were proposed to improve the waste of water resources. Water is essential for the industrial production of hydrogen. This study investigates the production of hydrogen from biomass and coal. To date, there are few studies focusing on the water footprint of biomass-to-hydrogen and coal-to-hydrogen processes. This research conducted a life cycle water use analysis on wheat straw biomass and coal to hydrogen via pyrolysis gasification processes. The results show that the water consumption of the entire biomass-to-hydrogen process was 76.77 L/MJ, of which biomass cultivation was the dominant contributor (99%). Conversely, the water consumption of the coal-to-hydrogen process was only 1.06 L/MJ, wherein the coal production stage accounted for only 4.15% for the total water consumption, which is far lower than that of the biomass-to-hydrogen process. The hydrogen production stage of biomass hydrogen production accounted for 76% of the total water consumption when excluding the water consumption of straw growth, whereas that of the coal hydrogen production stage was 96%. This research provides the associated water consumption, within a specified boundary, of both hydrogen production processes, and the influence of major factors on total water consumption was demonstrated using sensitivity analysis.

[en] As-synthesized hollow silica microspheres with micropores and thermally treated ones with mesopores were used as adsorbents. The two types of hollow microspheres have the same particle sizes and hollow centers, but with different pore sizes, surface areas, and pore volumes. The adsorption of rhodamine 6G and methyl blue on both hollow SiO₂ microspheres was investigated and compared. The time-dependent adsorption data were fitted with different kinetic models. The results indicate that the charges of the adsorbents and the dyes in water, the relative sizes of nanopores, and dye molecules played important roles in the adsorption capacity and the kinetics besides the surface area and pore volume of the adsorbents. As expected, an electrostatic attraction between the oppositely charged adsorbents and adsorbates, a large surface area and pore volume helped to increase the adsorption. More important is that the results evidence that when nanopores are relatively small compared with the size of dye molecules, dye molecules may have limited access and rate to go inside the hollows, resulting in a slow adsorption kinetics and low adsorption capacity. Graphical abstract: < Image>.

[en] Objective: To explore the feasibility of application of the Monte Carlo method to simulate the whole body dose distribution in patients with total body X (γ) ray irradiation by comparing the actual measurement results. Methods: A Monte Carlo model of a 6 MV Elekta Synergy Clinical linear accelerator was established by MCNPX. According to the relationship between the CT value and the density of the material, the CT of the ATOM physical phantom was converted into a voxel phantom for MCNPX calculation. The dose distribution of the whole body was simulated in the total body X (γ) ray irradiation. The simulated results were compared with the measurement values of the thermoluminescence dosimetry at different positions in the ATOM physical phantom to analyze the differences. Results: The difference between the depth dose curve and the off-axis dose curve and the actual measurement values calculated by the 6 MV accelerator treatment head model in the water tank was less than 2%, with the maximum dose depth of approximately 1.5 cm and field size of 10 cm × 10 cm, which were consistent with the actual measurement values. The maximum difference between the simulated results at different locations in the body and the thermoluminescence dosimeter was approximately 4%, and the simulated results of MCNPX were almost in good agreement with the results of thermoluminescence. Conclusions: The whole body dose distribution in patient with total body X (γ) ray irradiation can be accurately simulated by MCNPX. Monte Carlo simulation makes it possible to optimize the uniformity of the total body dose during the total body irradiation process. (authors)