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排序方式: 共有10000条查询结果,搜索用时 218 毫秒
1.
《International Journal of Hydrogen Energy》2022,47(56):23787-23796
Microbial electrosynthesis (MES) is an electrochemical reduction technology through which microorganisms attached to a cathode are driven by electricity to reduce carbon dioxide (CO2) into industrial chemicals. However, the limited contact time with biocatalysts affects the performance of MES because of low CO2 solubility. In this study, zeolitic imidazolate framework-8 (ZIF-8) particles with different pore diameters modified cathodes were prepared. Results showed that the ZIF-8 modified electrode obtained the maximum acetate production rate (0.13 g L?1 d?1), which was 1.4 times that of bare CF, and the accumulated acetate concentration reached 4.04 ± 0.1 g L?1 within 30 days. Brunauer–Emmett–Teller test and CO2 adsorption characteristic evaluation indicated that ZIF-8 had a high specific surface area and an excellent CO2 adsorption capacity. Scanning electron microscopy and microbial community analysis revealed that ZIF-8 modified electrodes were beneficial to biofilm formation and increased the enrichment of Acetobacterium and Arcobacter. Therefore, CO2-adsorbing materials modified electrodes are effective in improving the performance of MES. 相似文献
2.
Christopher J. Marvel Qirong Yang Scott D. Walck Kelvin Y. Xie Kristopher D. Behler Jerry C. LaSalvia Masashi Watanabe Richard A. Haber Martin P. Harmer 《Journal of the American Ceramic Society》2022,105(5):2990-3007
Compositional analysis of boron carbide on nanometer length scales to examine or interpret atomic mechanisms, for example, solid-state amorphization or grain-boundary segregation, is challenging. This work reviews advancements in high-resolution microanalysis to characterize multiple generations of boron carbide. First, ζ-factor microanalysis will be introduced as a powerful (scanning) transmission electron microscopy ((S)TEM) analytical framework to accurately characterize boron carbide. Three case studies involving the application of ζ-factor microanalysis will then be presented: (1) accurate stoichiometry determination of B-doped boron carbide using ζ-factor microanalysis and electron energy loss spectroscopy, (2) normalized quantification of silicon grain-boundary segregation in Si-doped boron carbide, and (3) calibration of a scanning electron microscope X-ray energy-dispersive spectroscopy (XEDS) system to measure compositional homogeneity differences of B/Si-doped arc-melted boron carbides in the as-melted and annealed conditions. Overall, the improvement and application of advanced analytical tools have helped better understand processing–microstructure–property relationships and successfully manufacture high-performance ceramics. 相似文献
3.
《Ceramics International》2022,48(2):2377-2384
Bi2O3, Y2O3 and MgO co-doped BaTiO3 (BT)-based X8R ceramics were synthesized successfully for the first time. The effects of the sintering temperature and Bi2O3, Y2O3 and MgO dopants on the dielectric properties were investigated systematically. Bi2O3 doping can increase the Curie temperature (Tc), but reduces the overall dielectric permittivity. On the other hand, Y2O3 doping is beneficial to the formation of core-shell microstructure and the increase of Tc, whereas MgO can prevent excessive Y2O3 from diffusing into grain core, and thereby further contributes to the generation of the core–shell microstructure. The generation of the typical core-shell microstructure was confirmed and investigated in detail by using transmission electron microscopy (TEM). It is argued that the synergistic effects of Bi2O3, Y2O3 and MgO co-doping in terms of the formation of the core-shell structure and the increase of Tc, can help improve the temperature stability of the dielectric permittivity effectively. Increasing the sintering temperature leads to an increase in the grain size, which in turn leads to an increase in the overall dielectric permittivity due to the grain size effect. 相似文献
4.
Suisui Zhang Jingying Li Yan Nie Luyao Qiang Boyang Bai Zhiwei Peng Xiaoxun Ma 《中国化学工程学报》2022,42(2):236-244
HFC-134a is a widely used environment-friendly refrigerant. At present, China is the largest producer of HFC-134a in the world. The production of HFC-134a in China mainly adopts the calcium carbide acetylene route. However, the production route has high resource and energy consumption and large waste emission, and few of the studies addressed on the environmental performance of its production process. This study quantified the environmental performance of HFC-134a production by calcium carbide route via carrying out a life cycle assessment (LCA) using the CML 2001 method. And uncertainty analysis by Monte-Carlo simulation was also carried out. The results showed that electricity had the most impact on the environment, followed by steam, hydrogen fluoride and chlorine, and the impact of direct CO2 emissions in calcium carbide production stage on the global warming effect also could not be ignored. Therefore, the clean energy (e.g., wind, solar, biomass, and natural gas) was used to replace coal-based electricity and coal-fired steam in this study, showing considerable environmental benefits. At the same time, the use of advanced production technologies could also improve environmental benefits, and the environmental impact of the global warming category could be reduced by 4.1% via using CO2 capture and purification technology. The Chinese database of HFC-134a production established in this study provides convenience for the relevant study of scholars. For the production of HFC-134a, this study helps to better identify the specific environmental hotspots and proposes useful ways to improve the environmental benefits. 相似文献
5.
6.
研究了镍基高温合金GH202在800~1100 ℃高温氧化后晶粒、碳化物和强化相的演变过程。采用透射电子显微镜、扫描电子显微镜和电子背散射衍射对其微观结构进行了表征。结果表明:镍基高温合金的硬度随氧化温度的升高而降低,1100 ℃氧化100 h后,硬度降低了43.5%。800和900 ℃氧化后晶粒生长速度较慢,而经900 ℃氧化后晶界碳化物析出显著增加。在1000和1100 ℃氧化后,晶粒尺寸明显增大。氧化过程中晶界迁移是由晶界两侧自由能差决定,温度越高,晶界向曲率中心迁移越快,大量细小晶粒被吞并形成了大晶粒。大块状碳化物(MC)分解成大量的碳原子,与Cr原子结合形成少量的富Cr颗粒状M23C6。在900 ℃氧化150 h后,M23C6演化为富Ti的M6C。随着氧化温度的升高,碳化物在γ相中回熔。在800、900和1000 ℃氧化后,γ′相逐渐长大,在1100 ℃氧化100 h后,完全溶解于γ相。 相似文献
7.
8.
《Ceramics International》2021,47(20):28260-28267
Piezoelectric materials are an indispensable part of modern life. Yet the existing environmental issues with conventional lead-based piezoelectrics has motivated scientist to develop novel substitutes including lead-free piezoelectric polymer composites. Following this path, the present research has focused on the fabrication of ternary composites of Polyvinylidene fluoride (PVDF)/Potassium Sodium Niobate (KNN)/nano-Silicon carbide (SiC) via hot compression molding and studying the effect of additives on the PVDF structure and the electrical properties of the composite. The obtained scanning electron micrographs and density measurements showed that the fabrication method provided dense samples. The activated polarization phenomena in the prepared samples enhanced dielectric permittivity and dielectric loss at a constant frequency with increasing KNN and SiC contents. Besides the expected dipole polarization, the presence of interfaces in the composites gave rise to the Maxwell–Wagner–Sillars effect and its corresponding polarization phenomenon. The semiconductive nature of SiC also promoted space charge polarization. However, these properties were frequency-dependent because the first two polarization mechanisms are deactivated at high frequencies. XRD patterns showed that SiC addition can alter the primary crystalline structure of PVDF and promote β-phase formation in the poled samples. Piezoelectric measurements confirmed the significant role of SiC addition to PVDF-KNN composites. The most significant increase in the piezoelectric properties was observed in PVDF-60KNN-1SiC, with a 183% increase in d33 value. The PVDF-80KNN-1SiC had the highest d33 value of 30.5 pC/N. It also had the best piezoelectric voltage coefficient and hence the highest figure of merit. Higher SiC contents restrict the efficiency of poling by forming a conductive path across the sample which would deteriorate the piezoelectric performance of the material. The present findings show that PVDF-KNN-SiC composites can be considered as a potential flexible piezoelectric material for future applications. 相似文献
9.
Yu-Hung Lee Ching-Fang Yu Ying-Chieh Yang Ji-Hong Hong Chi-Shiun Chiang 《International journal of molecular sciences》2021,22(4)
The low overall survival rate of patients with pancreatic cancer has driven research to seek a new therapeutic protocol. Radiotherapy (RT) is frequently an option in the neoadjuvant or palliative settings for pancreatic cancer treatment. This study explored the effect of RT protocols on the tumor microenvironment (TME) and their consequent impact on anti-programmed cell death ligand-1 (PD-L1) therapy. Using a murine orthotopic pancreatic tumor model, UN-KC-6141, RT-disturbed TME was examined by immunohistochemical staining. The results showed that ablative RT is more effective than fractionated RT at recruiting T cells. On the other hand, fractionated RT induces more myeloid-derived suppressor cell infiltration than ablative RT. The RT-disturbed TME presents a higher perfusion rate per vessel. The increase in vessel perfusion is associated with a higher amount of anti-PD-L1 antibody being delivered to the tumor. Animal survival is increased by anti-PD-L1 therapy after ablative RT, with 67% of treated animals surviving more than 30 days after tumor inoculation compared to a median survival time of 16.5 days for the control group. Splenocytes isolated from surviving animals were specifically cytotoxic for UN-KC-6141 cells. We conclude that the ablative RT-induced TME is more suited than conventional RT-induced TME to combination therapy with immune checkpoint blockade. 相似文献
10.
《Journal of the European Ceramic Society》2021,41(13):6290-6301
In this study, monolithic B4C and B4C-based ceramics incorporating FeNiCoCrMo dual-phase (FCC and BCC) high entropy alloys (HEAs) were produced by spark plasma sintering (SPS). The effect of additives on the densification behavior, mechanical properties, microstructures, and phase evaluation of the samples were investigated. X-ray analysis confirmed the existence of FCC structured HEA and depletion of BCC structured HEA, after high-temperature reaction between B4C-HEAs. The addition of HEAs enhanced the densification behavior by liquid phase sintering. Furthermore, hardness and fracture toughness values of the samples increased with increasing HEAs content. Fracture toughness and hardness values for all composites were higher than the monolithic B4C. A combination of the highest density (∼99.22 %) and the best mechanical properties (32.3 GPa hardness and 4.53 MPa m1/2 fracture toughness) was achieved with 2.00 vol.% HEA addition. 相似文献