Power Generation from Coke Oven Gas Using Chemical Looping Combustion: Thermodynamic Simulation

A chemical looping combustion (CLC) combined cycle with coke oven gas as fuel and NiO/NiAl₂O₄ as an oxygen carrier is proposed. The system was simulated by Aspen Plus® and the oxygen carrier circulation ratio was calculated. The effects of key operational temperatures and different gas turbines on the system performance were investigated. Under optimized conditions, a high CO₂ capture efficiency could be achieved. To capture CO₂ thoroughly, the PG6561B gas turbine can be employed, allowing for nearly 100 % CO₂ capture efficiency.     

Effects of spark plasma sintering on ferroelectricity of 0.8Bi3.15Nd0.85Ti3O12-0.2CoFe2O4 composite ceramic

The 0.8Bi_3.15Nd_0.85Ti₃O₁₂ (BNdT)-0.2CoFe₂O₄ (CFO) composite multiferroic ceramics have been fabricated by spark plasma sintering (SPS) at 850?°C. The relative density of as-sintered SPS ceramic reaches 97.4 (±0.3)%. The composites are composed of pure BNdT and CFO phases without any preferred c-orientation. The a-orientation preference is more obvious perpendicular to the pressure direction. The average grain-sizes of BNdT and CFO are 163 and 146?nm, respectively. The BNdT phase has more grains below 100?nm (～20%). The super energy-dispersive X-ray analyses suggest no serious reaction between BNdT and CFO. The Raman spectrum verifies the nano-structure of the SPS ceramic via the broadening bands and peak shifts. The Curie temperature of the SPS ceramic declines to 560?°C with stabilized dielectric loss. The grain boundary resistance plays a dominant role on impedance above 700?°C. The remanent polarization approaches to 15.2?μC/cm² (300?kV/cm) with lower coercive fields (?89/+95?kV/cm).     

Phase,microstructure and sintering of aluminum nitride powder by the carbothermal reduction-nitridation process with Y2O3 addition

Aluminum nitride powders were synthesized by carbothermal reduction-nitridation method using Al(OH)₃, carbon black and Y₂O₃ as raw materials. The change of phase, microstructure and densification during the AlN synthesis and sintering process were investigated and the effects of Y₂O₃ was discussed. The results showed that Y₂O₃ reacted with Al₂O₃ to form yttrium aluminates of YAlO₃ (orthorhombic and hexagonal phases), Y₄Al₂O₉ and Y₃Al₅O₁₂ at the low temperature of 1350 °C. YAlO₃ could firstly be transformed into Y₂O₃ and then completely into YN when the firing temperature and holding time increased. However, YN could be oxidized into Y₂O₃ again after the carbon removal at 700 °C in the air atmosphere. There were two ways generating AlN when adding Y₂O₃ and the possible mechanism was proposed. Y₂O₃ from YN oxidation favored the densification of AlN ceramics because the liquid had better flowability and distribution in the sintering process at 1800 °C.     

Ferroelastic domain structure and phase transition in single-crystalline [PbZn1/3Nb2/3O3]1-x[PbTiO3]x observed via in situ x-ray microbeam

(1-x)Pb(Zn_1/3Nb_2/3)O₃-xPbTiO₃ ((1-x)PZN-xPT in short) is one of the most important piezoelectric materials. In this work, we extensively investigated (1-x)PZN-xPT (x = 0.07–0.11) ferroelectric single crystals using in-situ synchrotron μXRD, complemented by TEM and PFM, to correlate microstructures with phase transitions. The results reveal that (i) at 25 °C, the equilibrium state of (1-x)PZN-xPT is a metastable orthorhombic phase for x = 0.07 and 0.08, while it shows coexistence of orthorhombic and tetragonal phases for x = 0.09 and x = 0.11, with all ferroelectric phases accompanied by ferroelastic domains; (ii) upon heating, the phase transformation in x = 0.07 is Orthorhombic → Monoclinic → Tetragonal → Cubic. The coexistence of ferroelectric tetragonal and paraelectric cubic phases was in-situ observed in x = 0.08 above Curie temperature (T_C), and (iii) phase transition can be explained by the evolution of the ferroelectric and ferroelastic domains. These results disclose that (1-x)PZN-xPT are in an unstable regime, which is possible factor for its anomalous dielectric response and high piezoelectric coefficient.     

99Tcm-MAG3-RRL肿瘤靶向肽的标记和性质鉴定

将具有肿瘤靶向性的精氨酸-精氨酸-亮氨酸（RRL）多肽与双功能螯合剂MAG₃相连，摸索其螯合⁹⁹Tc^m的适宜标记条件并评价探针的体外稳定性。标记利用SnCl₂还原法进行⁹⁹Tc^m标记，对影响标记的主要变量因素分别进行探究以获得适宜标记条件，采用纸层析法测定标记率和放射化学纯度。实验所得MAG₃-RRL纯度为98.94%，适宜标记条件下，标记率为93.67%±1.10%，纯化后放射化学纯度为94.32%±0.19%（n=3）。⁹⁹Tc^m-MAG₃-RRL在生理盐水和50%牛血清白蛋白（BSA）中放置，6 h内放射化学纯度均大于90%（n=3），在半胱氨酸溶液中的最高置换率为0.57%±0.21%，生理盐水对照为0.41%±0.04%（n=3，P＞0.05）。⁹⁹Tc^m-MAG₃-RRL的脂水分配系数为lg P=-0.15±0.01（n=3）。结果表明：MAG3可成功连接RRL多肽，并能进一步提高标记率；探针制备方法简单快速，体外稳定性好，为进一步的生物学实验提供了良好的基础。     

Controllable Fe/HCS catalysts in the Fischer-Tropsch synthesis: Effects of crystallization time

The Fischer–Tropsch synthesis (FTS) continues to be an attractive alternative for producing a broad range of fuels and chemicals through the conversion of syngas (H₂ and CO), which can be derived from various sources, such as coal, natural gas, and biomass. Among iron carbides, Fe₂C, as an active phase, has barely been studied due to its thermodynamic instability. Here, we fabricated a series of Fe₂C embedded in hollow carbon sphere (HCS) catalysts. By varying the crystallization time, the shell thickness of the HCS was manipulated, which significantly influenced the catalytic performance in the FTS. To investigate the relationship between the geometric structure of the HCS and the physic-chemical properties of Fe species, transmission electron microscopy, X-ray diffraction, N₂ physical adsorption, X-ray photoelectron spectroscopy, hydrogen temperature-programmed reduction, Raman spectroscopy, and Mössbauer spectroscopy techniques were employed to characterize the catalysts before and after the reaction. Evidently, a suitable thickness of the carbon layer was beneficial for enhancing the catalytic activity in the FTS due to its high porosity, appropriate electronic environment, and relatively high Fe₂C content.     

FCC-to-HCP Phase Transformation in CoCrNix Medium-Entropy Alloys

A hybrid first-principles/Monte Carlo simulation is combined with experiments to study the structure and elastic properties of CoCrNi_x (x = 1-0.5) alloys. The experimental X-ray diffraction patterns show that the structures have changed from the single-phase face-centered cubic (FCC) structure at x = 1-0.8 to the coexistence of FCC and the hexagonal close-packed structures at x = 0.7-0.5, which is further confirmed by calculations on mixing energies. The elastic moduli by calculation are basically in agreement with experiments. Room-temperature tension shows that the six alloys have a certain plasticity, the strength and plasticity of the alloys have a linear decrease with the decrease in Ni contents, and the plasticity of the alloys drops from 84 to 23%. Furthermore, first-principles density function theory calculations were employed to reveal the electronic and magnetic structures of alloys. The electron density of states for all alloys is asymmetrical, which illustrates that the alloys are ferromagnetism. It is found that Cr atoms can suppress the ferromagnetism of alloys, since Cr atoms have both positive and negative magnetic moments in all alloys.     

Enhancing General Corrosion Resistance of Biomedical High Nitrogen Nickel-Free Stainless Steel by Nitric Acid Passivation

A systematic study of nitric acid passivation was investigated to enhance the general corrosion resistance of biomedical high-nitrogen nickel-free stainless steels(HNSs).After passivation,the corrosion rate of HNS could dramatically reduce to 1/20 of the untreated in 37℃0.9 wt% NaCl solutions.Then,the passive film on HNS was analyzed by X-ray photoelectron spectroscopy.It was found that chromium enrichment in the passive film and nitrogen enrichment in the film/metal interface contributed to the improvement in general corrosion resistance of HNS.     

Effects of Ti and Cu on the Microstructure Evolution of AlCoCrFeNi High-Entropy Alloy During Heat Treatment

The microstructure evolution of AlCoCrFeNiTi_(0.5) alloy and AlCoCrFeNiCu alloy during heat treatment was systematically studied,to reveal the influence rules of chemical activity of adding element on the microstructure evolution of AlCoCrFeNi system.Owing to the negative mixing enthalpy with the constituent elements,Ti element was mainly dissolved in the Al-Nirich phases,and aggravated the lattice distortion of B2 phase.The structure variation of BCC phase by adding Ti inhibited the formation of FCC phase and enhanced the precipitation of σ phase during heat treatment.Owing to the positive mixing enthalpy with constituent elements,Cu element tended to be repelled to the ID region and formed metastable Cu-rich FCC1 phase which would transform into Cu-Al-Ni-rich FCC2 phase with increasing temperature.The addition of Cu inhibited the precipitation of σ phase during heat treatment.Adding Ti maintained the stable dendritic morphology,while adding Cu reduced the thermal stability of microstructure.Two dramatic morphology changes occurred at 1000~℃ and 1100~℃ in the AlCoCrFeNiCu alloy.The lattice distortion of phase in AlCoCrFeNiTi_(0.5) alloy was aggravated with increasing temperature up to 800~℃,then relaxed together with the dissolution of σ phase when temperature was above 900~℃.The variation in lattice distortion dominated the hardness of AlCoCrFeNiTi_(0.5) alloy.With increasing heating temperature,the increasing volume fraction of region with FCC structure due to the transformation between FCC phases,and the pronounced coarsening in microstructure due to the reduced thermal stability,resulted in the mainly decreasing trend in the hardness of AlCoCrFeNiCu alloy.     

Ca掺杂LNF阴极材料的制备与电化学性能改善

近年来，LaNi0.6Fe0.4O3-δ阴极材料在金属连接体下具有优异的抗铬毒化性能备受关注，但其电化学性能相对较低。本文通过Ca2+掺杂LaNi0.6Fe0.4O3-δ（LNF）阴极材料改善电化学性能，实验采用甘氨酸燃烧法制备La1-xCaxNi0.6Fe0.4O3-δ（LCNF）阴极材料,Ca2+掺杂量分别为0.05、0.10、0.15、0.20。应用X-Ray衍射表征材料的物相组成，SEM观察阴极材料的微观结构，XPS分析阴极材料表面元素的化学形态，电化学交流阻抗谱技术分析阴极材料的电化学活性。结果表明，LCNF阴极材料随着Ca2+掺杂量的增加，氧还原反应活化能减小，这一现象与DRT（弛豫时间分布）分析结果相吻合。LCNF(x=0.20)阴极材料在750℃具有最小的极化阻抗（0.88Ωcm2），与LNF阴极材料相比表现出更加优异的氧催化活性，使LCNF阴极材料在IT-SOFC具有更加广阔的应用前景。