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1.
Gas diffusion layer (GDL) is one of the most important components of fuel cells. In order to improve the fuel cell performance, GDL has developed from single layer to dual layers, and then to multiple layers. However, dual or multi layers in GDL are usually prepared by layer-by-layer methods, which cost too much time, energy, and resources. In this work, we successfully developed a facile one-step method to prepare a GDL with three functional layers by utilizing the different sedimentation rates and filtration rates of short carbon fiber (CF) and carbon nanotube (CNT). The treatment temperature for this GDL is much lower than that of traditional method. The thickness of the GDL can be effectively controlled from as thin as 50 μm to more than 200 μm by simply adjusting the content of CF. The GDL with high flexibility is suitable to develop high performance flexible electronics. The fuel cell with the GDL has the maximum power density 1021 mW cm?2, which shows 19% improvement comparing to the conventional one. Therefore, this work breaks the traditional concept that GDL for fuel cells only can be prepared by very complex and high-cost procedure.  相似文献   
2.
本文采用193 nm紫外激光解离质谱(UVPD-MS)研究非变性电喷雾条件下,超电荷试剂环丁砜对蛋白质序列、结构表征的影响。UVPD可在5 ns内对保持高级结构和非共价相互作用的不同价态碳酸酐酶进行快速激发解离,解离序列覆盖率达79.8%,具有较高的解离结构选择性。超电荷试剂环丁砜的引入可显著增加非变性电喷雾产生的碳酸酐酶离子的电荷数目,UVPD解离序列覆盖率提升至87.2%,实现对难解离区域的位点覆盖和序列、结构表征。加入环丁砜后,碳酸酐酶仍能保持高级结构谱学特征及与锌离子的非共价结合,锌离子结合区域等大部分结构区域的UVPD位点解离效率未见显著变化。但是,电荷数目的增加存在引起蛋白质局部结构变化的风险。  相似文献   
3.
《Ceramics International》2022,48(15):21268-21282
Mullite-Al2O3-SiC composites were in-situ synthesized through carbothermal reduction reaction of fly ash (FA) with a high alumina content and activated carbon (AC). The effects of sintering temperature, holding time, and amount of AC on the β-SiC yield, microstructure, dielectric properties, and electromagnetic (EM) absorption performance of the composites in the 2–18 GHz frequency range were studied. The results show that increasing the AC improves the porosities of the composites, with the highest porosity of 56.17% observed. The β-SiC yield varies considerably as the sintering parameters were altered, with a maximum yield of 23% achieved under conditions of 12 wt% AC, 1400 °C sintering temperature, and 3 h holding time. With a thickness of 3.5 mm, this composite has excellent EM absorption performance, exhibiting a minimum reflection loss (RLmin) of -51.55 dB at 7.60 GHz. Significantly, the maximum effective absorption bandwidth (EAB) reaches 3.39 GHz when the thickness is 3.0 mm. These results demonstrate that the composite prepared under ideal conditions can absorb 99.99% of the waves passing through it. Because of the interfacial polarization, conductive loss, and impedance matching of the heterostructure, the synthesized mullite-Al2O3-SiC composites with densities ranging from 1.43 g/cm3 to 1.62 g/cm3 demonstrate outstanding EM attenuation capabilities. Therefore, this study presents a remarkable way of utilizing fly ash to fabricate inexpensive, functional ceramic materials for EM absorption applications.  相似文献   
4.
甫沙4井位于塔里木盆地塔西南坳陷昆仑山前冲断带的柯东构造带上,北部和东部分别发育有柯克亚和柯东1井油气田。为研究甫沙4井原油来源与充注过程,对原油样品和连续抽提后的含油砂样各组分(游离态、束缚态、包裹体)进行GC、GC?MS和 GC?IRMS分析,与柯克亚凝析油气田油样进行油—油对比。结果表明:甫沙4井晚期充注原油组分具有C29?32重排藿烷、重排甾烷和Ts相对含量高,C27?29甾烷ααα 20R分布呈反“L”型,以及正构烷烃单体碳同位素值较低等特征,与柯克亚凝析油气田来源于二叠系普司格组(P2?3p)烃源岩的主体原油(I类)地球化学特征一致。而早期充注的原油组分具有重排藿烷、重排甾烷和Ts相对含量较低,C27?29甾烷ααα 20R分布呈“V”型,以及正构烷烃单体碳同位素值较高等特征,与柯克亚凝析油气田来源于中—下侏罗统湖相泥岩的II类原油地球化学特征一致。甫沙4井经历3个阶段成藏过程:①在上新世,二叠系烃源岩于生油晚期阶段生成的I类原油运移至柯克亚构造带或柯东构造带深部形成油藏;②在更新世早期,侏罗系烃源岩于生油早—中期生成的II类原油运移至甫沙4井白垩系储层;③在第四纪,强烈的构造作用使深部I类原油沿断裂调整进入甫沙4井白垩系储层。最终造成甫沙4井白垩系储层II类原油先充注,I类原油后充注的特殊现象。  相似文献   
5.
《Ceramics International》2022,48(1):754-759
Thermal control coatings (TCCs) are an essential part of the thermal control systems in the spacecraft. Solar absorptance and emittance are the key performance parameters of TCCs. To develop an ultra-low solar absorption and stable inorganic TCCs for surface radiator, different TCCs were prepared by co-sintering ZnO and SiO2 nanoparticles to form Zn2SiO4/SiO2 pigment in this work, and the optical properties and radiation stability were systematically studied. It is found that the coating based on composite pigment has high reflectivity in the ultraviolet band and excellent optical performance possessing the low solar absorption of 0.06. In addition, the Zn2SiO4/SiO2 coating demonstrates the highest proton and electron radiation stability because that SiO2 between Zn2SiO4 particles acts as the relaxation center of the defects caused by radiation.  相似文献   
6.
《Ceramics International》2022,48(14):20041-20052
The growing demand for radiation-resistant optical glasses for space and nuclear radiation applications has attracted significant research interest. However, radiation-resistant fluorophosphate glasses have been poorly studied. In this work, we report on the tailoring and performance of radiation-resistant fluorophosphate glasses that contained cerium through codoping with Sb2O3 and Bi2O3. The physical properties, optical properties, microstructure, and defects of fluorophosphate glasses were investigated using transmittance measurements, absorption measurements, as well as Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) spectroscopy. The results showed that the radiation resistance of all codoped fluorophosphate glasses was better than the undoped cerium-containing fluorophosphate glasses after 10–250 krad(Si) irradiation. Especially in glasses doped with Bi2O3, the optical density increment at 385 nm was only 0.1482 after 250 krad(Si) irradiation. The CeO2 prevented the development of phosphate-related oxygen hole center (POHC) defects, whereas further codoping with Bi2O3 suppressed the formation of oxygen hole center (OHC) and POEC defects, reducing the breaking of phosphate chains caused by CeO2. Bi3+ is more likely than Sb3+ to change the valence, affecting the transition equilibrium of intrinsic defects and reducing the concentration of defects produced by irradiation. When codoping with Sb2O3 and Bi2O3, Bi2O3 does not enhance radiation resistance owing to the scission effect of Sb2O3 on the phosphate chain, which is not conducive to the radiation resistance of glasses. This indicates that the cerium-containing fluorophosphate glasses doped with Bi2O3 can effectively suppress the defects caused by irradiation and improve the radiation resistance of the glasses.  相似文献   
7.
曾欣欣  白慧娟  俞娟  黄培  杨超  徐俊波 《化工学报》2022,73(6):2352-2369
基于面向空天动力用聚酰亚胺树脂基复合材料的背景,分析了复合材料面临的介尺度结构设计与调控的关键科学问题及研究思路。综述了国内外热塑性聚酰亚胺构-效设计、复合材料微/纳复合界面强化以及健康结构动态监测的基础研究,并提出了未来的发展趋势。  相似文献   
8.
In the last few decades, global warming, environmental pollution, and an energy shortage of fossil fuel may cause a severe economic crisis and health threats. Storage, conversion, and application of regenerable and dispersive energy would be a promising solution to release this crisis. The development of porous carbon materials from regenerated biomass are competent methods to store energy with high performance and limited environmental damages. In this regard, bio-carbon with abundant surface functional groups and an easily tunable three-dimensional porous structure may be a potential candidate as a sustainable and green carbon material. Up to now, although some literature has screened the biomass source, reaction temperature, and activator dosage during thermochemical synthesis, a comprehensive evaluation and a detailed discussion of the relationship between raw materials, preparation methods, and the structural and chemical properties of carbon materials are still lacking. Hence, in this review, we first assess the recent advancements in carbonization and activation process of biomass with different compositions and the activity performance in various energy storage applications including supercapacitors, lithium-ion batteries, and hydrogen storage, highlighting the mechanisms and open questions in current energy society. After that, the connections between preparation methods and porous carbon properties including specific surface area, pore volume, and surface chemistry are reviewed in detail. Importantly, we discuss the relationship between the pore structure of prepared porous carbon with surface functional groups, and the energy storage performance in various energy storage fields for different biomass sources and thermal conversion methods. Finally, the conclusion and prospective are concluded to give an outlook for the development of biomass carbon materials, and energy storage applications technologies. This review demonstrates significant potentials for energy applications of biomass materials, and it is expected to inspire new discoveries to promote practical applications of biomass materials in more energy storage and conversion fields.  相似文献   
9.
李姣  苏继磊  陈敏  尹浩 《食品科学》2022,43(4):119-126
为探索马氏珍珠贝肉的水解规律及快速鉴定血管紧张素转化酶(angiotensin-converting enzyme,ACE)抑制活性肽,本研究以不同时间(2、4、6、8、10 h)的酶解物为对象,采用三羟甲基甘氨酸-十二烷基硫酸钠-聚丙烯酰胺凝胶电泳、分子质量分布、反相高效液相色谱(reversed-phase high performance liquid chromatography,RP-HPLC)表征其水解规律。另外,对10 h酶解物进行初步分离纯化,鉴定高活性组分中的肽序列,并采用分子对接的方法对鉴定的肽进行筛选,验证筛选肽的活性,阐释其抑制机理。结果表明,马氏珍珠贝肉在酶解过程中,大分子质量蛋白逐渐水解为小分子肽,在RP-HPLC上出现某一特征峰的富集。初步分离后,发现F2、F3组分具有较高的ACE抑制活性,从这2 个组分中共获得了可信度较高的54 个肽序列。分子对接筛选出6 个潜在的ACE抑制肽,在1 mg/mL时,5 个肽具有不同程度的ACE抑制活性,其中,WFHAVFW和WHAFLW显示了最高的ACE抑制活性,分别为(95.57±0.37)%和(98.59±0.08)%,进一步测定六肽WHAFLW的半抑制浓度(IC50)值,为52.39 μmol/L。分子对接显示肽的抑制机理可能是通过氢键、范德华作用以及Pi-Pi作用形成稳定的肽-酶复合物。本研究既揭示了珍珠贝肉蛋白不同酶解时间的规律变化,又将活性实验跟踪与计算机辅助筛选相结合,提供了一种快速筛选酶解物中高活性ACE抑制肽的方法。  相似文献   
10.
To reduce the energy consumption of the shrimp blanching process and improve the economic value of the blanched product, a transcritical CO2 heat pump blanching system (THPB system) was designed in this paper. The trends of astaxanthin were investigated at atmospheric pressure near boiling temperature, combined with the color and structural properties of shrimp samples, and the optimal blanching times of 270 s and 240 s were obtained at 90°C and 95°C, respectively. In contrast to the fuel blanching system (FB system) at 100°C, the annual standard coal consumption of the THPB system with 90°C blanching is decreased by 79%, and the annual operating cost can be saved by CNY 63,800, with a payback period of about 3.13 years.Industrial relevanceBlanching is one of the effective ways to prolong the shelf life of shrimp. However, the research on the blanching time and temperature of shrimp is not comprehensive. In addition, the traditional fuel blanching process has high energy consumption and pollution, and can no longer meet the quality requirements of the modern food processing industry. Heat pump has been shown to have better performance in food drying, but it is less used in blanching. The information presented in this study may provide other insights into food processing.  相似文献   
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