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Your search keyword '"Feng, Renfei"' showing total 254 results
Start Over Author "Feng, Renfei" Publication Type Academic Journals
254 results on '"Feng, Renfei"'

7. Microbial response to copper oxide nanoparticles in soils is controlled by land use rather than copper fate

Author

Rippner, Devin A, Margenot, Andrew J, Fakra, Sirine C, Aguilera, L Andrea, Li, Chongyang, Sohng, Jaeeun, Dynarski, Katherine A, Waterhouse, Hannah, McElroy, Natalie, Wade, Jordon, Hind, Sarah R, Green, Peter G, Peak, Derek, McElrone, Andrew J, Chen, Ning, Feng, Renfei, Scow, Kate M, and Parikh, Sanjai J

Subjects
Medical Biotechnology, Agricultural, Veterinary and Food Sciences, Biomedical and Clinical Sciences, Forestry Sciences, Nanotechnology, Bioengineering, Life on Land, Other Chemical Sciences, Environmental Engineering, Environmental Biotechnology
Abstract

Copper (Cu) products, including copper oxide nanoparticles (nCuO), are critically important agricultural fungicides and algaecides. Foliar application onto crops and subsequent aerosol drift of these Cu products, especially nCuO, on to soil may alter nutrient cycling and microbial communities in both managed and unmanaged environments. We measured the influence of land use on soil microbial biomass and respiration in response to the addition of nCuO to an alluvial soil. Different land uses included grassland, forest and both organic and conventional managed row crops. Soil samples were amended with 1000 mg Cu per kg soil as CuCl2, 16 nm CuO (16nCuO), 42 nm CuO (42nCuO), and larger than nanoparticle sized bulk CuO (bCuO). Copper availability immediately increased in all soils following Cu addition in the order of CuCl2 > 16nCuO > 42nCuO > bCuO. After 70 days Cu availability was diminished across land uses and lowest in soils treated with bCuO. Using X-ray absorption near edge structure (XANES) spectroscopy, we determined that the relatively high availability of Cu after treatment with nanoparticle sized CuO was due to the dissolution of CuO particles and subsequent adsorption by soil materials. Respiration, an indicator of microbial activity, was suppressed by Cu additions, especially CuCl2. Copper effects on soil microbial biomass were sensitive to land use. In agricultural soils, microbial biomass was unaltered by Cu form, regardless of concentration, whereas in unmanaged soils, it decreased following exposure to CuCl2 and 42nCuO. Our results suggest that land use history has little impact on Cu chemical fate in soils, but strongly modulates microbial response to Cu exposure. These results are especially important for organic agricultural systems where copper fungicides are widely used but may suppress microbial mineralization of nutrients from soil organic matter.

Published
2021

27. Self‐Powered System for H2 Production and Biomass Upgrading.

Author

Liu, Shao‐Qing, Xie, Shiyan, Wu, Shuwen, Yang, Yang, Lei, Peng‐Xia, Luo, Shuiping, Feng, Renfei, Fu, Xian‐Zhu, and Luo, Jing‐Li

Subjects
HYDROGEN evolution reactions, HYDROGEN production, BIOMASS production, SEPARATION of gases, COPPER
Abstract

Hydrazine‐oxidation‐assisted self‐powered H2 generation system greatly expands the applicability of hydrogen production technology. However, the high cost of hydrazine greatly impedes the widespread adoption of hydrazine‐contained energy systems for large‐scale H2 production. Besides, the gaseous products of hydrazine splitting, comprising a mixture of H2 and N2, necessitate energy‐intensive downstream separation. Here, taking advantage of a low‐potential furfural oxidation reaction (FOR) on the Cu electrode, a self‐powered H2 production system by integrating a direct furfural fuel cell (DFFC) and a bipolar H2 production electrolyser is reported. Ru‐dispersed Cu nanowire with remarkable catalytic activity is developed as a hydrogen evolution reaction (HER) catalyst to couple with the FOR. The HER‐FOR electrolyzer achieves bipolar H2 production with an apparent 200% Faradaic efficiency, attaining a current density of 100 mA cm−2 with a low cell voltage of 0.43 V. The DFFC displays an open circuit potential of 0.969 V and a peak power density up to 193 mW cm−2. Inspired by the bipolar H2 production that eliminates the gas separation, a self‐powered system utilizing furfural as the sole consumable, which yields a pure H2 production rate of 6 mmol h−1 m−2 is demonstrated. This work provides a new avenue for constructing self‐powered H2 production systems. [ABSTRACT FROM AUTHOR]

Published
2024
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42. Analysis of microscopy techniques to measure segregation in continuous‐cast steel slabs.

Author

Al Rafi, Araf, Santillana, Begoña, Feng, Renfei, Thomas, Brian G., and Phillion, André B.

Subjects
CONTINUOUS casting, ELECTRONIC probes, REGRESSION analysis, SPATIAL resolution, DENDRITES
Abstract

Summary: The accurate characterisation of centreline segregation requires precise measurements of composition variations over large length scales (10−1$^{-1}$m${\rm {m}}$) across the centreline of the cast product, while having high resolution, sufficient to quantify the significant composition variations between dendrites due to microsegregation at very small length scales (10−5m$^{-5}{\rm {m}}$). This study investigates the potential of a novel microscopy technique, named Synchrotron Micro X‐ray Flurorescence (SMXRF), to generate large‐scale high‐resolution segregation maps from a steel sample taken from a thin slab caster. Two methods, Point Analysis and Regression Analysis, are proposed for SMXRF data calibration. By comparing with the traditional Laser‐Induced Breakdown Spectroscopy (LIBS), and Electron Probe Micro Analyser (EPMA) techniques, we show that SMXRF is successful in quantitative characterisation of centreline segregation. Over large areas (e.g. 12 ×$\times$ 16 mm2${\rm {mm}}^2$) and at high resolution (10–50 μm$\mu\text{m}$ pixel size) various techniques yield comparable outcomes in terms of composition maps and solute profiles. The findings also highlight the importance of both high spatial resolution and large field of view to have a quantitative, accurate, and efficient measurement tool to investigate segregation phenomena. [ABSTRACT FROM AUTHOR]

Published
2024
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