scholarly journals In-situ 4D-STEM imaging to develop a fundamental understanding of coupled transport of vacancies

2021 ◽  
Vol 27 (S1) ◽  
pp. 2202-2202
Author(s):  
Sean Mills ◽  
Yang Yang ◽  
Andrew M Minor
Keyword(s):  
Coupled Transport ◽  
Fundamental Understanding

Photocatalytic reforming of glycerol for H2 evolution on Pt/TiO2: fundamental understanding the effect of co-catalyst Pt and the Pt deposition route

2015 ◽  
Vol 3 (5) ◽  
pp. 2271-2282 ◽  
Author(s):  
Xiaoliang Jiang ◽  
Xianliang Fu ◽  
Li Zhang ◽  
Sugang Meng ◽  
Shifu Chen
Keyword(s):  
Active Sites ◽  
H2 Evolution ◽  
Co Catalyst ◽  
Fundamental Understanding

The effects of deposited Pt and its deposition route on the photocatalytic reforming of glycerol for H2 evolution over Pt/TiO2 were investigated. Intimately loaded Pt(0) particles are the key active sites for the reaction, the formation of which was favored by an in situ photo-deposition route.

Novel Nitrospira-like bacteria as dominant nitrite-oxidizers in biofilms from wastewater treatment plants: diversity and in situ physiology

2000 ◽  
Vol 41 (4-5) ◽  
pp. 85-90 ◽  
Author(s):  
H. Daims ◽  
P.H. Nielsen ◽  
J.L. Nielsen ◽  
S. Juretschko ◽  
M. Wagner
Keyword(s):  
Wastewater Treatment ◽  
In Situ Hybridization ◽  
16S Rrna ◽  
Fluorescent In Situ Hybridization ◽  
Wastewater Treatment Plants ◽  
Combined Application ◽  
Fundamental Understanding ◽  
Unculturable Bacteria ◽  
Rrna Sequences

The frequency and distribution of putatively nitrite-oxidizing, Nitrospira- like bacteria in nitrifying biofilms from two reactors receiving wastewater with different ammonia and salt concentrations were observed by fluorescent in situ hybridization. For this purpose, new 16S rRNA-directed oligonucleotide probes targeting the bacterial phylum Nitrospira and the three main lineages within this phylum were developed and evaluated. The diversity of Nitrospira-like bacteria in the reactors was additionally investigated by retrieval and comparative analysis of full 16S rRNA sequences from the biofilms. We found that, despite of the differences in the influent composition, Nitrospira-like bacteria form dominant populations in both reactors. In addition, first insights into the physiology of these still unculturable bacteria were obtained by the incubation of active biofilm samples with radioactively labeled substrates followed by the combined application of fluorescent in situ hybridization and microautoradiography. The results are discussed in consideration of the frequently observed dominance of Nitrospira-like bacteria in nitrifying bioreactors. Consequently, high priority should be assigned to future studies on the ecology and physiology of these organisms in order to increase our fundamental understanding of nitrogen cycling and to enable knowledge-driven future improvements of nitrifying wastewater treatment plants.

scholarly journals In-situ STEM study on the morphological evolution of copper-based nanoparticles during high-temperature redox reactions

Nanoscale ◽  
2021 ◽  
Author(s):  
Sharmin Afroz Sharna ◽  
Mounib Bahri ◽  
Corinne Bouillet ◽  
Virgile Rouchon ◽  
Arnold Lambert ◽  
...  
Keyword(s):  
High Temperature ◽  
Copper Nanoparticles ◽  
Redox Reactions ◽  
Morphological Evolution ◽  
Industrial Applications ◽  
Fundamental Understanding

Despite the broad relevance of copper nanoparticles in industrial applications, the fundamental understanding of oxidation and reduction of copper at the nanoscale is still a matter of debate and remains...

scholarly journals Vector analysis of electric-field-induced antiparallel magnetic domain evolution in ferromagnetic/ferroelectric heterostructures

2021 ◽  
Author(s):  
Xinger Zhao ◽  
Zhongqiang Hu ◽  
Jingen Wu ◽  
Ting Fang ◽  
Yaojin Li ◽  
...  
Keyword(s):  
Electric Field ◽  
Magnetic Domain ◽  
Vector Analysis ◽  
Magnetization Distribution ◽  
Magnetic Domains ◽  
Practical Applications ◽  
Domain Evolution ◽  
Fundamental Understanding ◽  
Multiferroic Heterostructures

AbstractElectric field (E-field) control of magnetism based on magnetoelectric coupling is one of the promising approaches for manipulating the magnetization with low power consumption. The evolution of magnetic domains under in-situ E-fields is significant for the practical applications in integrated micro/nano devices. Here, we report the vector analysis of the E-field-driven antiparallel magnetic domain evolution in FeCoSiB/PMN-PT(011) multiferroic heterostructures via in-situ quantitative magneto-optical Kerr microscope. It is demonstrated that the magnetic domains can be switched to both the 0° and 180° easy directions at the same time by E-fields, resulting in antiparallel magnetization distribution in ferromagnetic/ferroelectric heterostructures. This antiparallel magnetic domain evolution is attributed to energy minimization with the uniaxial strains by E-fields which can induce the rotation of domains no more than 90°. Moreover, domains can be driven along only one or both easy axis directions by reasonably selecting the initial magnetic domain distribution. The vector analysis of magnetic domain evolution can provide visual insights into the strain-mediated magnetoelectric effect, and promote the fundamental understanding of electrical regulation of magnetism.

HREM study of phase transformation induced by ion irradiation in Al-Cu-Co-Ge single decagonal quasicrystal

1996 ◽  
Vol 54 ◽  
pp. 722-723
Author(s):  
L.F. Chen ◽  
L.M. Wang ◽  
R.C. Ewing
Keyword(s):  
Phase Transformation ◽  
Ion Irradiation ◽  
National Laboratory ◽  
Research Field ◽  
In Situ Tem ◽  
Decagonal Quasicrystal ◽  
University Of New Mexico ◽  
Fundamental Understanding ◽  
The University

Irradiation-induced phase transformation in crystals has been an interesting research field for the past twenty years. Since the discovery of quasicrystals in Al-based alloys, there have been some reports on irradiation-induced phase transformation in quasicrystals by in situ TEM observations. However, detailed study on phase transformation in quasicrystals under ion irradiation at atomic level using HREM is necessary for the fundamental understanding of the process. In this paper, we report the results from a systematic HREM study on phase transformation induced by ion irradiation in Al-Cu-Co-Ge single decagonal quasicrystal (31.4 wt.% Cu, 21.8 wt.% Co and 5.4 wt.% Ge).The TEM specimens of single decagonal quasicrystal were prepared perpendicular to the tenfold axis. The transformation in single quasicrystal was studied by in situ TEM during 1.5 MeV Xe+ ion irradiation at room temperature using the HVEM-Tandem Facility at Argon National Laboratory and examined in detail by HREM using a JEM2010 microscope at the University of New Mexico after the irradiation.

Effects of Metallic Impurities in Alkaline Electrolytes on Electro-Oxidation of Water and Alcohol Molecules

2021 ◽  
Author(s):  
Yi Shen ◽  
Yongfang Zhou ◽  
Hongying Li
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electrochemical Measurements ◽  
Metallic Ions ◽  
Impurity Effects ◽  
X Ray ◽  
Fundamental Understanding ◽  
Alkaline Electrolytes ◽  
Electro Oxidation ◽  
Metallic Impurities

Abstract The presence of metallic impurities in the electrolyte greatly affects electrocatalytic performance. A systematic study on this topic can not only provide guidance for rigorous practices on electrochemical measurements, but also in-depth fundamental understanding on the mechanisms of the electrochemical reactions. Herein, nine types of metallic ions including Cu2+, Ni2+, Fe3+, Fe2+, Co2+, Mn2+, Zn2+, Ce3+ and Al3+ are intentionally introduced into the electrolytes with a controlled manner and their effects on electro-oxidation of water, 5-hydroxymethylfurfural (HMF) and glycerol are investigated in details. Among these metal ions, Co2+ has the most pronounced effects on H2O electro-oxidation while Cu2+ species displays superior activity toward HMF and glycerol electro-oxidation, but negligible effects on H2O electro-oxidation. Such a unique feature of Cu2+ can also be noted from electro-oxidation of other small molecules, such as ethylene glycol, ethanol and furfural. More importantly, the effects of metallic impurities are independent of the composition of the electrodes, only rely on the pH of the electrolytes. In-situ electrochemical Raman spectroscopy, control electrochemical experiments and X-ray photoelectron spectroscopy analyses reveal that the origin of impurity effects is attributed to the formation of hydroxides during the electrochemical measurements.

scholarly journals Technical note: A high-resolution inverse modelling technique for estimating surface CO<sub>2</sub> fluxes based on the NIES-TM – FLEXPART coupled transport model and its adjoint

2020 ◽  
Author(s):  
Shamil Maksyutov ◽  
Tomohiro Oda ◽  
Makoto Saito ◽  
Rajesh Janardanan ◽  
Dmitry Belikov ◽  
...  
Keyword(s):  
High Resolution ◽  
Transport Model ◽  
Dispersion Model ◽  
Surface Flux ◽  
Particle Dispersion ◽  
Anthropogenic Emissions ◽  
Coupled Transport ◽  
Tracer Transport ◽  
Flux Corrections

Abstract. We developed a high-resolution surface flux inversion system based on the global Lagrangian–Eulerian coupled tracer transport model composed of National Institute for Environmental Studies Transport Model (NIES-TM) and FLEXible PARTicle dispersion model (FLEXPART). The inversion system is named NTFVAR (NIES-TM-FLEXPART-variational) as it applies variational optimisation to estimate surface fluxes. We tested the system by estimating optimized corrections to natural surface CO2 fluxes to achieve best fit to atmospheric CO2 data collected by the global in-situ network, as a necessary step towards capability of estimating anthropogenic CO2 emissions. We employ the Lagrangian particle dispersion model (LPDM) FLEXPART to calculate the surface flux footprints of CO2 observations at a 0.1° × 0.1° spatial resolution. The LPDM is coupled to a global atmospheric tracer transport model (NIES-TM). Our inversion technique uses an adjoint of the coupled transport model in an iterative optimization procedure. The flux error covariance operator is being implemented via implicit diffusion. Biweekly flux corrections to prior flux fields were estimated for the years 2010–2012 from in-situ CO2 data included in the Observation Package (ObsPack) dataset. High-resolution prior flux fields were prepared using Open-Data Inventory for Anthropogenic Carbon dioxide (ODIAC) for fossil fuel combustion, Global Fire Assimilation System (GFAS) for biomass burning, the Vegetation Integrative SImulator for Trace gases (VISIT) model for terrestrial biosphere exchange and Ocean Tracer Transport Model (OTTM) for oceanic exchange. The terrestrial biospheric flux field was constructed using a vegetation mosaic map and separate simulation of CO2 fluxes at daily time step by the VISIT model for each vegetation type. The prior flux uncertainty for terrestrial biosphere was scaled proportionally to the monthly mean Gross Primary Production (GPP) by the Moderate Resolution Imaging Spectroradiometer (MODIS) MOD17 product. The inverse system calculates flux corrections to the prior fluxes in the form of a relatively smooth field multiplied by high-resolution patterns of the prior flux uncertainties for land and ocean, following the coastlines and vegetation productivity gradients. The resulting flux estimates improve fit to the observations at continuous observations sites, reproducing both the seasonal variation and short-term concentration variability, including high CO2 concentration events associated with anthropogenic emissions. The use of high-resolution atmospheric transport in global CO2 flux inversion has the advantage of better resolving the transport from the mix of the anthropogenic and biospheric sources in densely populated continental regions and shows potential for better separation between fluxes from terrestrial ecosystems and strong localised sources such as anthropogenic emissions and forest fires. Further improvements in the modelling system are needed as the posterior fit is better than that by the National Oceanic and Atmospheric Administration (NOAA) CarbonTracker only for a fraction of the monitoring sites, mostly at coastal and island locations experiencing mix of background and local flux signals.

Monitoring the Change of Viscosity during Cure Reaction of Epoxy Resins with Resin Position Sensor

2002 ◽  
Vol 21 (2) ◽  
pp. 139-152 ◽  
Author(s):  
Jung Gon Kim ◽  
Kyoung Hoon Shin ◽  
Ho Seok Ryu ◽  
Jae Wook Lee
Keyword(s):  
Epoxy Resin ◽  
Complex Viscosity ◽  
Diglycidyl Ether ◽  
Gel Point ◽  
Position Sensor ◽  
Degree Of Cure ◽  
Cure Reaction ◽  
Fundamental Understanding ◽  
Viscosity Changes

It was required that the fundamental understanding of the resin’s rheological properties, such as viscosity, gel point and degree of cure are known during the processing of epoxy resin. In order to monitor these properties in-situ, a sensor system that can measure the viscosity changes during cure is needed. The resin position sensor (RPS) based on DC conductometry has been able to measure the ionic contents and electrical conductivity of most organic resins. Complex viscosity and electrical resistance were measured simultaneously during the cure of diglycidyl ether of bisphenol-A (DGEBA) epoxy resin with polyamide by mounting the RPS on the upper plate of rotational rheometer. To correlate the viscosity with the resistance, the rheological model for the viscosity changes and the electrical model for the resistance changes were used. From the results, the interrelationship of viscosity and resistance of epoxy resin could be confirmed.

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