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1.
The catalyst layer of the cathode is arguably the most critical component of low‐temperature fuel cells and carbon dioxide (CO2) electrolysis cells because their performance is typically limited by slow oxygen (O2) and CO2 reduction kinetics. While significant efforts have focused on developing cathode catalysts with improved activity and stability, fewer efforts have focused on engineering the catalyst layer structure to maximize catalyst utilization and overall electrode and system performance. Here, we study the performance of cathodes for O2 reduction and CO2 reduction as a function of three common catalyst layer preparation methods: hand‐painting, air‐brushing, and screen‐printing. We employed ex‐situ X‐ray micro‐computed tomography (MicroCT) to visualize the catalyst layer structure and established data processing procedures to quantify catalyst uniformity. By coupling structural analysis with in‐situ electrochemical characterization, we directly correlate variation in catalyst layer morphology to electrode performance. MicroCT and SEM analyses indicate that, as expected, more uniform catalyst distribution and less particle agglomeration, lead to better performance. Most importantly, the analyses reported here allow for the observed differences over a large geometric volume as a function of preparation methods to be quantified and explained for the first time. Depositing catalyst layers via a fully‐automated air‐brushing method led to a 56% improvement in fuel cell performance and a significant reduction in electrode‐to‐electrode variability. Furthermore, air‐brushing catalyst layers for CO2 reduction led to a 3‐fold increase in partial CO current density and enhanced product selectivity (94% CO) at similar cathode potential but a 10‐fold decrease in catalyst loading as compared to previous reports. 相似文献
2.
Interconnected Frameworks with a Sandwiched Porous Carbon Layer/Graphene Hybrids for Supercapacitors with High Gravimetric and Volumetric Performances 下载免费PDF全文
A facile approach to synthesize porous disordered carbon layers as energy storage units coating on graphene sheets to form interconnected frameworks by one‐step pyrolysis of the mixture of graphene oxide/polyaniline and KOH is presented. As effective energy storage units, these porous carbon layers play an important role in enhancing the electrochemical performances. The obtained porous carbon material exhibits a high specific surface area (2927 m2 g?1), hierarchical interconnected pores, moderate pore volume (1.78 cm3 g?1), short ion diffusion paths, and a high nitrogen level (6 at%). It displays both unparalleled gravimetric (481 F g?1) and outstanding volumetric capacitance (212 F cm?3) in an aqueous electrolyte. More importantly, the assembled symmetrical supercapacitor delivers not only high gravimetric (25.7 Wh kg?1 based on total mass of electroactive materials) but also high volumetric energy densities (11.3 Wh L?1) in an aqueous electrolyte. Furthermore, the assembled asymmetric supercapacitor yields a maximum energy density up to 88 Wh kg?1, which is, to the best of our knowledge, the highest value so far reported for carbon//MnO2 asymmetric supercapacitors in aqueous electrolytes. Therefore, this novel carbon material holds great promise for potential applications in energy‐related technological fields. 相似文献
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Carbon dioxide (CO2) is one of the end products of fuel combustion and the major component of the greenhouse gases. The reduction of atmospheric CO2 not only decreases environmental pollution but also produces value‐added chemicals, solving energy and environment issues simultaneously. One significant challenge is the low conversion efficiency of CO2 reduction due to the inertness of the CO2 molecule. The design of the catalyst nanomaterials with the high selectivity, stability, and the activation capabilities for the conversion of CO2 is needed. Atomic layer deposition (ALD), capable of constructing catalysts with atomic‐level precision in a highly controllable manner, is a promising technique to address the key problems in CO2 reduction. This review explores the application of ALD in CO2 reduction, emphasizing the designs of the efficient catalyst nanomaterials fabricated by the ALD technique and their applications in CO2 reduction and capture. The significance of the ALD catalysts with the fine structures is highlighted to obtain a better understanding of the catalytic performance–aimed benefits as well as an outlook on the ALD‐designed catalysts for the reduction of CO2. 相似文献
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Mengqi Shi Qing Dai Fan Li Tianyu Li Guangjin Hou Huamin Zhang Xianfeng Li 《Liver Transplantation》2020,10(34)
Membranes with precise control of selective layer are designed and prepared by adjusting diffusion of solvents. Combining experiments and theoretical calculations, the formation mechanism of ion conductive membranes prepared by a non‐solvent induced phase separation (NIPS) method is found to be related to internal diffusion flux of solvent to the non‐solvent bath and external diffusion flux of non‐solvent to the casting solution. By regulating the internal and external diffusion rates via a two‐step NIPS method, a series of polybenzimidazole (PBI) porous membranes with independently controlled thin selective skin layers and highly porous support layers are fabricated, which achieve a simultaneous improvement in ion selectivity and proton conductivity. A vanadium flow battery assembled with a PBI membrane demonstrates an energy efficiency of 80% at a current density of 220 mA cm?2, which is the highest value among the reported PBI membranes. This provides a simple and effective way to fabricate membranes with well‐defined morphologies. 相似文献
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Seongyu Lee Kwang Hun Park Jong‐Hoon Lee Hyungcheol Back Min Jae Sung Jinho Lee Jehan Kim Heejoo Kim Yun‐Hi Kim Soon‐Ki Kwon Kwanghee Lee 《Liver Transplantation》2019,9(14)
Although high power conversion efficiency of over 14% has been achieved using nonfullerene acceptors (NFAs) in organic photovoltaics (OPVs), securing their insensitive device performance to the thickness of the photoactive layer remains an indispensable requirement for their successful commercialization via printing technologies. In this study, by synthesizing a new series of ITIC‐based NFAs having alkyl or alkoxy groups, it is found that the bulk heterojunction morphology dependence on the thickness of the photoactive layer becomes more severe as the difference in the surface energy of the donor and acceptor increases. It is believed that this observation is the origin that yields the device performance dependence on the thickness of the photoactive layer. Through sensitive control of the surface energy of these ITIC‐based NFAs, it is demonstrated that thickness‐insensitive OPVs can be achieved even using a doctor blade technique under air without using any additives. It is believed that present approach provides an important insight into the design of photoactive materials and morphology control for the printable OPVs using NFAs. 相似文献
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A Universal Interface Layer Based on an Amine‐Functionalized Fullerene Derivative with Dual Functionality for Efficient Solution Processed Organic and Perovskite Solar Cells 下载免费PDF全文
Hamed Azimi Tayebeh Ameri Hong Zhang Yi Hou Cesar Omar Ramirez Quiroz Jie Min Mengyao Hu Zhi‐Guo Zhang Thomas Przybilla Gebhard J. Matt Erdmann Spiecker Yongfang Li Christoph J. Brabec 《Liver Transplantation》2015,5(8)
8.
Tomoko Hasegawa Tadamichi Akagi Munemitsu Yoshikawa Kenji Suda Hiroshi Yamada Yugo Kimura Hideo Nakanishi Masahiro Miyake Noriyuki Unoki Hanako Ohashi Ikeda Nagahisa Yoshimura 《PloS one》2015,10(6)
Objective
To examine microcystic inner nuclear layer (INL) changes in glaucomatous eyes and to determine associated factors.Design
Retrospective, cross-sectional, observational study.Methods
Two hundred seventeen eyes of 133 patients with primary open angle glaucoma (POAG), 41 eyes of 32 patients with preperimetric glaucoma and 181 normal eyes of 117 subjects were ultimately included. Microcystic INL lesions were examined with infrared fundus images and with 19 vertical spectral domain optical coherence tomography (SD-OCT) images in the macular area.Results
Microcystic INL changes were observed in 6.0% of eyes with POAG, but none of the normal eyes or eyes with preperimetric glaucoma showed microcystic INL changes. The proportion of eyes with advanced glaucoma was significantly larger (P = 0.013) in eyes with microcystic lesions than without. The visual field mean deviation (MD) slope was also significantly worse (P = 0.027) in eyes with microcystic lesions. No significant differences were observed in age, sex, refraction, axial length, intraocular pressure, or MD value between eyes with and without microcystic INL lesions. In several cases, microcystic INL lesions occurred along with glaucomatous visual field progression. The retinal nerve fiber layer (RNFL) thickness (P = 0.013) and ganglion cell layer (GCL) + inner plexiform layer thickness (P = 0.023) were significantly lower in areas with microcystic lesions than without. The INL was also significantly thicker (P = 0.002) in areas with microcystic lesions.Conclusions
Microcystic INL lesions in glaucomatous eyes are closely associated with RNFL and GCL thinning and correlated with worse MD slope. These INL lesions may indicate focal and progressive damage in glaucoma. 相似文献9.
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Andrea Capasso Fabio Matteocci Leyla Najafi Mirko Prato Joka Buha Lucio Cinà Vittorio Pellegrini Aldo Di Carlo Francesco Bonaccorso 《Liver Transplantation》2016,6(16)
Solution‐processed few‐layer MoS2 flakes are exploited as an active buffer layer in hybrid lead–halide perovskite solar cells (PSCs). Glass/FTO/compact‐TiO2/mesoporous‐TiO2/CH3NH3PbI3/MoS2/Spiro‐OMeTAD/Au solar cells are realized with the MoS2 flakes having a twofold function, acting both as a protective layer, by preventing the formation of shunt contacts between the perovskite and the Au electrode, and as a hole transport layer from the perovskite to the Spiro‐OMeTAD. As prepared PSC demonstrates a power conversion efficiency (η) of 13.3%, along with a higher lifetime stability over 550 h with respect to reference PSC without MoS2 (Δη/η = ?7% vs. Δη/η = ?34%). Large‐area PSCs (1.05 cm2 active area) are also fabricated to demonstrate the scalability of this approach, achieving η of 11.5%. Our results pave the way toward the implementation of MoS2 as a material able to boost the shelf life of large‐area perovskite solar cells in view of their commercialization. 相似文献
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Hamsa Jaganathan Sucharita Mitra Srimeenakshi Srinivasan Bhuvanesh Dave Biana Godin 《PloS one》2014,9(4)
Efficient therapeutics and early detection has helped to increase breast cancer survival rates over the years. However, the recurrence of breast cancer remains to be a problem and this may be due to the presence of a small population of cells, called tumor initiating cells (TICs). Breast TICs are resistant to drugs, difficult to detect, and exhibit high self-renewal capabilities. In this study, layer by layer (LBL) small interfering RNA (siRNA) nanovectors (SNVs) were designed to target breast TICs. SNVs were fabricated using alternating layers of poly-L-lysine and siRNA molecules on gold (Au) nanoparticle (NP) surfaces. The stability, cell uptake, and release profile for SNVs were examined. In addition, SNVs reduced TIC-related STAT3 expression levels, CD44+/CD24−/EpCAM+ surface marker levels and the number of mammospheres formed compared to the standard transfection agent. The data from this study show, for the first time, that SNVs in LBL assembly effectively delivers STAT3 siRNA and inhibit the growth of breast TICs in vitro. 相似文献
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Timm Oberwahrenbrock Maria Weinhold Janine Mikolajczak Hanna Zimmermann Friedemann Paul Ingeborg Beckers Alexander U. Brandt 《PloS one》2015,10(9)
Purpose
Measurement of intra-retinal layer thickness using optical coherence tomography (OCT) has become increasingly prominent in multiple sclerosis (MS) research. Nevertheless, the approaches used for determining the mean layer thicknesses vary greatly. Insufficient data exist on the reliability of different thickness estimates, which is crucial for their application in clinical studies. This study addresses this lack by evaluating the repeatability of different thickness estimates.Methods
Studies that used intra-retinal layer segmentation of macular OCT scans in patients with MS were retrieved from PubMed. To investigate the repeatability of previously applied layer estimation approaches, we generated datasets of repeating measurements of 15 healthy subjects and 13 multiple sclerosis patients using two OCT devices (Cirrus HD-OCT and Spectralis SD-OCT). We calculated each thickness estimate in each repeated session and analyzed repeatability using intra-class correlation coefficients and coefficients of repeatability.Results
We identified 27 articles, eleven of them used the Spectralis SD-OCT, nine Cirrus HD-OCT, two studies used both devices and two studies applied RTVue-100. Topcon OCT-1000, Stratus OCT and a research device were used in one study each. In the studies that used the Spectralis, ten different thickness estimates were identified, while thickness estimates of the Cirrus OCT were based on two different scan settings. In the simulation dataset, thickness estimates averaging larger areas showed an excellent repeatability for all retinal layers except the outer plexiform layer (OPL).Conclusions
Given the good reliability, the thickness estimate of the 6mm-diameter area around the fovea should be favored when OCT is used in clinical research. Assessment of the OPL was weak in general and needs further investigation before OPL thickness can be used as a reliable parameter. 相似文献15.
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Slime layers are being studied in our laboratories in an attempt to understand their functions in the control of pollution in natural streams. A method for fixing, staining, and embedding microorganisms in the intact slime has been developed. In this method, epoxy resin discs are placed in a holder and are introduced into a simulated stream. After various periods of time the discs are punched out of the holder into the fixative. The disc with the attached slime is fixed, stained (4% osmium tetroxide plus ruthenium red), dehydrated, and embedded in epoxy resin so that thin sections can be cut through the vertical plane of the slime mass. Such thin sections permit detailed examination of the attached layer, the surface-slime interface, the spatial relationships between cells in the vertical slime structure, and the strands of extracellular material between and around cells. No special attachment structures were noted as the cells appeared to be attached to the surface by extracellular material alone. This material was observed in strands and netlike forms between cells which are positioned 1 to 4 mum apart in the slime. 相似文献
17.
Colette Serruya 《Hydrobiologia》1972,40(3):355-359
Summary Chemical and biological investigations of Lake Kinneret showed that reducing conditions prevailling in summer in the metalimnion cause an early and intense denitrification process accompanied by the release of dissolved Fe and Mn. These conditions are favourable to the development of sulfo-bacteria and blue green algae. The role of this layer is discussed. 相似文献
18.
The Boundary Layer over a Populus Leaf 总被引:6,自引:0,他引:6
Air flow over a Populus leaf was investigated using a hot-wireanemometer. When the air flow in the wind tunnel was laminar,the boundary layer was often turbulent at a wind speed of only1.5 m s1, particularly when encouraged by uneven topographyand roughness of the surface, as on the lower side of the leaf.The smoother upper surface behaved in a similar way to a flatplate when at low wind speeds, and the profiles of wind speedcould be shown to be equivalent to those expected from laminarboundary layer theory. Nevertheless, the boundary layer becameturbulent at Reynolds numbers much lower than those requiredto cause the transition to turbulence in a flat plate. Turbulentair flow in the wind tunnel greatly increased boundary layerturbulence but had only a small effect on evaporation from amodel of the leaf. The evaporation rates observed were 2.5 timeshigher than expected from theory, irrespective of the turbulenceregime. 相似文献
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A New Interconnecting Layer of Metal Oxide/Dipole Layer/Metal Oxide for Efficient Tandem Organic Solar Cells 下载免费PDF全文
Shunmian Lu Xing Guan Xinchen Li Wei E. I. Sha Fengxian Xie Hongchao Liu Jiannong Wang Fei Huang Wallace C. H. Choy 《Liver Transplantation》2015,5(17)
A new metal‐oxide‐based interconnecting layer (ICL) structure of all‐solution processed metal oxide/dipole layer/metal oxide for efficient tandem organic solar cell (OSC) is demonstrated. The dipole layer modifies the work function (WF) of molybdenum oxide (MoO x ) to eliminate preexisted counter diode between MoO x and TiO2. Three different amino functionalized water/alcohol soluble conjugated polymers (WSCPs) are studied to show that the WF tuning of MoO x is controllable. Importantly, the results show that S‐shape current density versus voltage (J–V) characteristics form when operation temperature decreases. This implies that thermionic emission within the dipole layer plays critical role for helping recombination of electrons and holes. Meanwhile, the insignificant homotandem open‐circuit voltage (V oc) loss dependence on dipole layer thickness shows that the quantum tunneling effect is weak for efficient electron and hole recombination. Based on this ICL, poly(3‐hexylthiophene) (P3HT)‐based homotandem OSC with 1.20 V V oc and 3.29% power conversion efficiency (PCE) is achieved. Furthermore, high efficiency poly(4,8‐bis(5‐(2‐ethylhexyl)‐thiophene‐2‐yl)‐benzo[1,2‐b54,5‐b9]dithiophene‐alt alkylcarbonylthieno[3,4‐b]thiophene) (PBDTTT‐C‐T)‐based homotandem OSC with 1.54 V V oc and 8.11% PCE is achieved, with almost 15.53% enhancement compared to its single cell. This metal oxide/dipole layer/metal oxide ICL provides a new strategy to develop other qualified ICL with different hole transporting layer and electron transporting layer in tandem OSCs. 相似文献