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排序方式: 共有7263条查询结果,搜索用时 31 毫秒
1.
《International Journal of Hydrogen Energy》2022,47(47):20617-20631
Morphology of carbon nanofibers significantly effects Pt nanoparticles dispersion and specific interaction with the support, which is an important aspect in the fuel cell performance of the electrocatalysts. This study emphasizes, the defects creation and structural evolution comprised due to N–F co-doping on graphitic carbon nanofibers (GNFs) of different morphologies, viz. GNF-linearly aligned platelets (L), antlers (A), herringbone (H), and their specific interaction with Pt nanoparticle in enhancing the oxygen reduction reaction (ORR). GNFs–NF–Pt catalysts exhibit better ORR electrocatalytic activity, superior durability that is solely ascribed to the morphological evolution and the doped N–F heteroatoms, prompting the charge density variations in the resultant carbon fiber matrices. Amongst, H–NF–Pt catalyst performed outstanding ORR activity with exceptional electrochemical stability, which shows only 20 mV loss in the half-wave potential whilst 100 mV loss for Pt/C catalyst on 20,000 potential cycling. The PEMFC comprising H–NF–Pt as cathode catalyst with minimum loading of 0.10 mg cm?2, delivers power density of 0.942 W cm?2 at current density of 2.50 A cm?2 without backpressures in H2–O2 feeds. The H–NF–Pt catalyst owing to its hierarchical architectures, performs well in PEMFC at the minimized catalyst loading with outstanding stability that can significantly decrease total price for the fuel cell. 相似文献
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Leucokinins (LKs) constitute a family of neuropeptides identified in numerous insects and many other invertebrates. LKs act on G-protein-coupled receptors that display only distant relations to other known receptors. In adult Drosophila, 26 neurons/neurosecretory cells of three main types express LK. The four brain interneurons are of two types, and these are implicated in several important functions in the fly’s behavior and physiology, including feeding, sleep–metabolism interactions, state-dependent memory formation, as well as modulation of gustatory sensitivity and nociception. The 22 neurosecretory cells (abdominal LK neurons, ABLKs) of the abdominal neuromeres co-express LK and a diuretic hormone (DH44), and together, these regulate water and ion homeostasis and associated stress as well as food intake. In Drosophila larvae, LK neurons modulate locomotion, escape responses and aspects of ecdysis behavior. A set of lateral neurosecretory cells, ALKs (anterior LK neurons), in the brain express LK in larvae, but inconsistently so in adults. These ALKs co-express three other neuropeptides and regulate water and ion homeostasis, feeding, and drinking, but the specific role of LK is not yet known. This review summarizes Drosophila data on embryonic lineages of LK neurons, functional roles of individual LK neuron types, interactions with other peptidergic systems, and orchestrating functions of LK. 相似文献
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《Ceramics International》2021,47(20):28557-28565
To reduce the energy consumption of cooling in the hot summer days, searching for novel NIR shielding materials for buildings is of great value. In this report, monodispersed F doped TiO2 nanocrystals with an average size of 8.6 nm were synthesized as novel solar shielding materials for energy-saving windows. All the products adopted an anatase TiO2 structure. After doping of F ions, the morphology of TiO2 was transformed from an irregular shape to a pseudospherical shape. The Raman shift and XPS depth analysis confirmed the successful doping of F− ions into the lattice oxygen sites in the TiO2 structure. The introduction of F− ions generated free electrons and bulk Ti3+ in TiO2 crystals, which activated a localized surface plasmon resonance (LSPR) absorption in the NIR region. Correspondingly, the NIR shielding performance of the TiO2 films improved with increasing F doping amounts. The NIR shielding value of the films increased from 1.3% to 43.2% when the molar ratio of F to Ti increased from 0 to 0.3. The reason can be attributed to the enhanced NIR absorption induced by the increased electron concentration after doping of fluorine ions. The F–TiO2 films showed superior visible transmittance (90.1–96.7%). Moreover, the F–TiO2 films lowered the indoor temperature of the heat box by 5.3 °C in the thermal tests. Overall, the prepared F–TiO2 nanocrystals show a great potential to be used for energy-saving windows. 相似文献
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Present study highlights the development of carbon-loaded SBA 15 membrane on clay-alumina tubular support and its performance on the CO2 separation efficiencies from different mixture gases. To modify the large pores of SBA 15 by graphitic carbon, low molecular weight phenol–formaldehyde (PF) resin was incorporated into the mesoporous channel followed by calcination under inert atmosphere. The modified ordered pore structure of the membrane has been characterized by low-angle XRD, TEM, and pore size distribution analysis. The chemical state of the deposited carbon phase into the SBA 15 pores was analyzed by X-ray photoelectron and Raman spectroscopy. Carbon having graphitic nature mainly in graphene oxide has been deposited into the mesopore of SBA 15 resulting decrease in pore size from 8.9 to 1.0 nm. Finally, the developed SBA 15 carbon membranes were characterized by CO2 permeation and separation selectivity of CO2/CH4, CO2/CO. Highest CO2/CH4 separation factor was achieved as 16.9 with CO2 permeance 13.6 × 10–8 mol/m2/s/Pa at 200 kPa feed pressure by the 20% resin with 2 times coated membrane. In flue gas analysis, highest CO2/CO separation factor of 32.8 was achieved. This study offers an observation on CO2 separation from simulated BF gas for the first time and the results show the potential of the developed SBA 15/C composite membranes in commercial application. 相似文献
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Wen Zhang Jiangsheng Zhang 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2018,40(4):394-399
Bio-ethanol production from algae is a promising way to help solve the energy problem. Alginate is a major component of algae, but it cannot be utilized by existing ethanol fermentation microorganisms. In order to improve the utilization rate of brown algae, high alginate fermentation strains should be obtained. In this research, strains for algae fermentation were got from several experiments. The ethanol yield of strain A was the highest, which was 0.095 g/g (ethanol to alginate). The identification of strain A was carried out and it was 99% identical to Pantoea sp. F16-PCAi-T3P21. Fermentation experiments with different substrates were carried out, such as laminaran, mannitol, L. japonica and acid hydrolysate of L. japonica, and the ethanol yield rate of L. japonica acid hydrolysate was the highest, which reached 0.17 g/g ethanol to L. japonica. It showed that strain A can converse alginate to ethanol in a relatively high yield rate, and might be a promising strain with L. japonica as the substrate, we believe more research should be carried out on this strain. 相似文献
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分析黄毛草莓的果实品质和香气成分并对比其他栽培品种的差异,为其品质特性评价和香气利用奠定基础。通过直接滴定法、酸碱滴定法、福林酚法、直接法、2,6-二氯靛酚滴定法和质构仪测定法对4种草莓(黄毛草莓、密宝、哈尼、R7)的还原糖、总酸、总酚、花色苷、维生素C和硬度共6项指标进行测定,综合比较4种草莓的品质;运用顶空固相微萃取和气相色谱—质谱联用技术分析草莓果实的香气成分并做聚类分析。结果显示,在营养价值方面,黄毛草莓综合评分值仅次于哈尼排在第2位,高于密宝和R7。在果实香气方面,黄毛草莓的香气鉴定物质种类最多为83种,密宝有66种,哈尼有64种,R7有57种。在4种草莓的挥发物中,酯类是主要的挥发物(30.23%~52.70%),其中黄毛草莓的酯类相对含量最高(52.70%)。构成黄毛草莓特征香气的主要成分是香味酯:异戊酸乙酯、己酸乙酯、辛酸乙酯、乙酸辛酯、甲酸辛酯、癸酸乙酯、乙酸癸酯、香味醇反式-2-己烯-1-醇。黄毛草莓香气主成分聚类分析的结果显示,黄毛草莓和其他3个栽培品种分为两类,在香气主成分上与其他3种栽培品种存在显著差异。黄毛草莓中富含多种香精香料与洗护产品等行业所需的特殊香气成分,具有极大应用潜力。 相似文献
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范燕 《常州信息职业技术学院学报》2021,(2):29-32
本系统以STM32F103RCT6单片机为核心控制芯片,可以一键自动测量容器内液体的重量和液位参数,并显示测量数据、判别液体种类。使用激光与浮板进行液位测量;使用压力传感器与24位AD转化模块HX711进行高精度的重量测量;利用pH值传感器、光电传感器、导电率传感器获得液体不同的物理特性,区分液体种类。系统模块构成主要包括单片机系统模块、电源模块、激光测距模块、称重模块、传感器模块、OLED显示模块和按键模块,具有多功能、测量准确、反应速度快的特点。 相似文献