Visualization of Liquid Water Accumulation in PEMFCs Operating at Different Temperatures by Soft X-ray Radiography

Liquid water distribution in the operational PEMFC was visualized by soft X-ray radiography. To achieve a maximum sensitivity towards liquid water, low electron beam energy in soft X-ray range was chosen. As a result, the spatial resolution of 1 μm and the temporal resolution of 0.5 sec were obtained. In addition, a correlation between the accumulation of water and the reduction of performance in higher current density range was observed. At low current densities, liquid water accumulation was observed under the ribs, because the longer diffusion length for the rib area conduced to a less effective water removal into the vapor phase. With increase of current density, liquid water was also observed under the channels and the reduction of performance with time was observed. These results suggested that the current density under the rib is much less than under the channel and the anisotropy of GDL and the geometry of flow field had a heavy impact on the liquid water distribution and the cell performance.

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Effect of PEFC Rib/Channel Width on Liquid Water Accumulation and Discharge by In-situ X-Ray Imaging

ECS Transactions ◽

10.1149/09208.0147ecst ◽

2019 ◽

Vol 92 (8) ◽

pp. 147-152

Author(s):

Takahiro Komiyama ◽

Takashi Sasabe ◽

Katsuyuki Kawamura ◽

Hiroshi Naito ◽

Shuichiro Hirai

Keyword(s):

Liquid Water ◽

Channel Width ◽

X Ray ◽

X Ray Imaging ◽

Water Accumulation

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A Superhydrophobic, Antibacterial, and Durable Surface of Poplar Wood

Nanomaterials ◽

10.3390/nano11081885 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1885

Author(s):

Xinyu Wu ◽

Feng Yang ◽

Jian Gan ◽

Zhangqian Kong ◽

Yan Wu

Keyword(s):

Stearic Acid ◽

Antibacterial Properties ◽

Alkali Resistance ◽

Poplar Wood ◽

X Ray Diffraction ◽

X Ray ◽

Different Temperatures ◽

Acid And Alkali Resistance ◽

The Stability

The silver particles were grown in situ on the surface of wood by the silver mirror method and modified with stearic acid to acquire a surface with superhydrophobic and antibacterial properties. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray energy spectroscopy (XPS) were used to analyze the reaction mechanism of the modification process. Scanning electron microscopy (SEM) and contact angle tests were used to characterize the wettability and surface morphology. A coating with a micro rough structure was successfully constructed by the modification of stearic acid, which imparted superhydrophobicity and antibacterial activity to poplar wood. The stability tests were performed to discuss the stability of its hydrophobic performance. The results showed that it has good mechanical properties, acid and alkali resistance, and UV stability. The durability tests demonstrated that the coating has the function of water resistance and fouling resistance and can maintain the stability of its hydrophobic properties under different temperatures of heat treatment.

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Relationship between Hydrogen-Bonding Motifs and the 1b1 Splitting in the X-ray Emission Spectrum of Liquid Water

The Journal of Physical Chemistry Letters ◽

10.1021/acs.jpclett.1c00486 ◽

2021 ◽

Vol 12 (16) ◽

pp. 3996-4002

Author(s):

Vinícius Wilian D. Cruzeiro ◽

Andrew Wildman ◽

Xiaosong Li ◽

Francesco Paesani

Keyword(s):

Hydrogen Bonding ◽

Emission Spectrum ◽

Liquid Water ◽

X Ray

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Effect of calcination temperature on rare earth tailing catalysts for catalytic methane combustion

Green Processing and Synthesis ◽

10.1515/gps-2020-0053 ◽

2020 ◽

Vol 9 (1) ◽

pp. 734-743

Author(s):

Ran Zhao ◽

ZiChen Tian ◽

Zengwu Zhao

Keyword(s):

Rare Earth ◽

Mine Tailings ◽

Photoelectron Spectroscopy ◽

Methane Combustion ◽

Space Velocity ◽

High Catalytic Activity ◽

Reduction Peak ◽

X Ray ◽

Different Temperatures ◽

Bayan Obo

AbstractBayan Obo tailings are rich in rare earth elements (REEs), iron, and other catalytic active substances. In this study, mine tailings were calcined at different temperatures and tested for the catalytic combustion of low-concentration methane. Upon calcination at 600°C, high catalytic activity was revealed, with 50% CH4 conversion at 587°C (space velocity of 12,000 mL/g h). The physicochemical properties of catalysts were characterized using thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, hydrogen temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS). Compared to the raw ore sample, the diffraction peak intensity of Fe2O3 increased post calcination, whereas that of CeCO3F decreased. A porous structure appeared after the catalyst was calcined at 600°C. Additionally, Fe, Ce, Ti, and other metal elements were more highly dispersed on the catalyst surface. H2-TPR results revealed a broadening of the reduction temperature range for the catalyst calcined at 600°C and an increase in the reduction peak. XPS analysis indicated the presence of Ce in the form of Ce3+ and Ce4+ oxidation states and the coexistence of Fe in the form of Fe2+ and Fe3+. Moreover, XPS revealed a higher surface Oads/Olatt ratio. This study provides evidence for the green reuse of Bayan Obo mine tailings in secondary resources.

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Hydrothermal Ageing and Its Effect on Fracture Load of Zirconia Dental Implants

Materials ◽

10.3390/ma14113103 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3103

Author(s):

Laurent Gremillard ◽

Agnès Mattlet ◽

Alexandre Mathevon ◽

Damien Fabrègue ◽

Bruno Zberg ◽

...

Keyword(s):

Dental Implants ◽

Fracture Load ◽

Accelerated Ageing ◽

Dental Ceramics ◽

X Ray Diffraction ◽

X Ray ◽

Dental Restorations ◽

Different Temperatures ◽

Mechanical Performances ◽

Kinetics Of

Due to growing demand for metal-free dental restorations, dental ceramics, especially dental zirconia, represent an increasing share of the dental implants market. They may offer mechanical performances of the same range as titanium ones. However, their use is still restricted by a lack of confidence in their durability and, in particular, in their ability to resist hydrothermal ageing. In the present study, the ageing kinetics of commercial zirconia dental implants are characterized by X-ray diffraction after accelerated ageing in an autoclave at different temperatures, enabling their extrapolation to body temperature. Measurements of the fracture loads show no effect of hydrothermal ageing even after ageing treatments simulated a 90-year implantation.

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Modeling of magneto-conductivity of bismuth selenide: a topological insulator

SN Applied Sciences ◽

10.1007/s42452-021-04397-8 ◽

2021 ◽

Vol 3 (4) ◽

Author(s):

Yogesh Kumar ◽

Rabia Sultana ◽

Prince Sharma ◽

V. P. S. Awana

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Single Crystal ◽

Single Crystals ◽

X Ray Diffraction ◽

Field Range ◽

X Ray ◽

Bulk Carriers ◽

Different Temperatures

AbstractWe report the magneto-conductivity analysis of Bi2Se3 single crystal at different temperatures in a magnetic field range of ± 14 T. The single crystals are grown by the self-flux method and characterized through X-ray diffraction, Scanning Electron Microscopy, and Raman Spectroscopy. The single crystals show magnetoresistance (MR%) of around 380% at a magnetic field of 14 T and a temperature of 5 K. The Hikami–Larkin–Nagaoka (HLN) equation has been used to fit the magneto-conductivity (MC) data. However, the HLN fitted curve deviates at higher magnetic fields above 1 T, suggesting that the role of surface-driven conductivity suppresses with an increasing magnetic field. This article proposes a speculative model comprising of surface-driven HLN and added quantum diffusive and bulk carriers-driven classical terms. The model successfully explains the MC of the Bi2Se3 single crystal at various temperatures (5–200 K) and applied magnetic fields (up to 14 T).

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