scholarly journals X-ray fluorescence modelling for Solar system regoliths: Effects of viewing geometry, particle size, and surface roughness

2006 ◽  
Vol 2 (S236) ◽  
pp. 243-250
Author(s):  
Jyri Näränen ◽  
Hannu Parviainen ◽  
Karri Muinonen
Keyword(s):  
Surface Roughness ◽  
Solar System ◽  
Spherical Particles ◽  
Motion Model ◽  
X Ray ◽  
Composition And Structure ◽  
Solar System Objects ◽  
First Results ◽  
Brownian Motion Model ◽  
Tracing Techniques

AbstractSoft X-ray fluorescent emission from the surfaces of asteroids and other atmosphereless solar-system objects is studied using ray-tracing techniques. X-ray observations allow the assessment of the elemental composition and structure of the surface. The model regolith is assumed to consist of close-packed uniformly distributed spherical particles of equal size. The surface is also assumed to be rough according to a fractional-Brownian-motion model. The fluorescent X-ray emission from regolith surfaces is simulated in order to better understand the contribution of viewing-geometry -related phenomena on the signal obtained from, e.g., orbiting platforms. The first results are presented and the applicability of the methods to the interpretation of future asteroid and Mercury mission X-ray data (e.g., BepiColombo) is discussed.

Influence of Cu2+ Doping on the Photocatalytic Activity of TiO2 Film

2008 ◽  
Vol 368-372 ◽  
pp. 1483-1485 ◽  
Author(s):  
Rui Hai Cui ◽  
Zhao Hua Jiang ◽  
Zhong Ping Yao
Keyword(s):  
Aqueous Solution ◽  
Surface Roughness ◽  
Atomic Force Microscopy ◽  
Photocatalytic Activity ◽  
Degradation Rate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Composition And Structure

With the approach of anodic oxidation, TiO2/Ti film doped with Cu2+ was produced in H2SO4 electrolyte mixed with CuSO4. The surface morphology and the roughness of the films were studied with atomic force microscopy. The phase composition of the films was studied by X-ray diffraction. The photocatalytic activity of the films was compared through the photocatalytic degradation rate of phenol. The relations of the photocatalytic activity to the concentration of Cu2+, the microstructure and the surface roughness of the film were investigated. The results showed that Cu2+ increased the surface roughness and restrained the growth of crystal. In addition, the phenol in aqueous solution was successfully photodegraded under visible light irradiation by Cu2+-TiO2/Ti film. The composition and structure of the film affected the catalytic activity greatly. Compared with TiO2/Ti film, the recombination rate of e- and h+ of Cu2+-TiO2/Ti film was decreased.

Surveying the Trans-Neptunian Solar System with TESS

2020 ◽  
Author(s):  
Malena Rice ◽  
Greg Laughlin
Keyword(s):  
Solar System ◽  
Light Curve ◽  
Parameter Space ◽  
Outer Solar System ◽  
Orbital Geometry ◽  
Solar System Objects ◽  
First Results ◽  
Rule Out

<p>In recent years, the observed orbital geometry of extreme trans-Neptunian objects (TNOs) has provided tantalizing evidence predicting the existence of an as-yet undiscovered “Planet Nine.” Combined with orbit stability models, these observations permit a detailed prediction of Planet Nine's properties, with a shrinking parameter space as more of these rare objects are discovered. I will present the first results from a new survey utilizing light curve data from the Transiting Exoplanet Survey Satellite (TESS) to search for TNOs at distances 70-800 au, with a magnitude limit V~22. This survey leverages an innovative new pipeline designed to extract the locations, magnitudes, and 27-day orbital arcs of undiscovered outer solar system objects, including both Planet Nine and the population of extreme trans-Neptunian objects pertinent to the Planet Nine theory, using a blind shift-stacking search along all plausible outer solar system orbits. Together with the extensive sky coverage of the TESS survey, this search will place stringent constraints upon the as-yet undiscovered TNO population, with great potential to either discover Planet Nine or almost entirely rule out its existence.</p>

scholarly journals Preparation of Porous Hydroxyapatite Using Cetyl Trimethyl Ammonium Bromide as Surfactant for the Removal of Lead Ions from Aquatic Solutions

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1617
Author(s):  
Silviu-Adrian Predoi ◽  
Carmen Steluta Ciobanu ◽  
Mikael Motelica-Heino ◽  
Mariana Carmen Chifiriuc ◽  
Monica Luminita Badea ◽  
...  
Keyword(s):  
Cetyl Trimethyl Ammonium Bromide ◽  
Morphological Changes ◽  
Low Cost ◽  
Lead Ions ◽  
Ammonium Bromide ◽  
Porous Hydroxyapatite ◽  
X Ray ◽  
Composition And Structure ◽  
Cetyl Trimethyl Ammonium ◽  
Co Precipitation

In the present study, a new low-cost bioceramic nanocomposite based on porous hydroxyapatite (HAp) and cetyl trimethyl ammonium bromide (CTAB) as surfactant was successfully obtained by a simple chemical co-precipitation. The composition and structure of the HAp-CTAB were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscope (SEM) equipped with an energy dispersive X-ray (EDX) spectrometer, and N2 adsorption/desorption analysis. The capacity of HAp-CTAB nanocomposites to remove the lead ions from aqueous solutions was studied by adsorption batch experiments and proved by Langmuir and Freundlich models. The Pb2+ removal efficiency of HAp-CTAB biocomposite was also confirmed by non-destructive ultrasound studies. The cytotoxicity assays showed that the HAp-CTAB nanocomposites did not induce any significant morphological changes of HeLa cells after 24 h of incubation or other toxic effects. Taken together, our results suggests that the obtained porous HAp-CTAB powder could be used for the decontamination of water polluted with heavy metals, such as Pb2+.

On tungstates of divalent cations (III) – Pb5O2[WO6]

2020 ◽  
Vol 235 (8-9) ◽  
pp. 311-317
Author(s):  
Stephan G. Jantz ◽  
Florian Pielnhofer ◽  
Henning A. Höppe
Keyword(s):  
Crystal Structure ◽  
Thermal Analysis ◽  
Quantum Chemical ◽  
Density Functional ◽  
Divalent Cations ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
First Results ◽  
Electrostatic Calculations

Abstract${\text{Pb}}_{5}{\text{O}}_{2}\left[{\text{WO}}_{6}\right]$ was discovered as a frequently observed side phase during our investigation on lead tungstates. Its crystal structure was solved by single-crystal X-ray diffraction ($P{2}_{1}/n$, $a=7.4379\left(2\right)$ Å, $b=12.1115\left(4\right)$ Å, $c=10.6171\left(3\right)$ Å, $\beta =90.6847\left(8\right)$°, $Z=4$, ${R}_{\text{int}}=0.038$, ${R}_{1}=0.020$, $\omega {R}_{2}=0.029$, 4188 data, 128 param.) and is isotypic with ${\text{Pb}}_{5}{\text{O}}_{2}\left[{\text{Te}}_{6}\right]$. ${\text{Pb}}_{5}{\text{O}}_{2}\left[{\text{WO}}_{6}\right]$ comprises a layered structure built up by non-condensed [WO6]${}^{6-}$ octahedra and ${\left[{\text{O}}_{4}{\text{Pb}}_{10}\right]}^{12+}$ oligomers. The compound was characterised by spectroscopic measurements (Infrared (IR), Raman and Ultraviolet–visible (UV/Vis) spectra) as well as quantum chemical and electrostatic calculations (density functional theory (DFT), MAPLE) yielding a band gap of 2.9 eV fitting well with the optical one of 2.8 eV. An estimation of the refractive index based on the Gladstone-Dale relationship yielded $n\approx 2.31$. Furthermore first results of the thermal analysis are presented.

Embracing Uncertainty: Modeling the Standard Uncertainty in Electron Probe Microanalysis—Part I

2020 ◽  
Vol 26 (3) ◽  
pp. 469-483
Author(s):  
Nicholas W. M. Ritchie
Keyword(s):  
Surface Roughness ◽  
Expert System ◽  
Coating Thickness ◽  
Electron Probe ◽  
Uncertainty Modeling ◽  
Measurement Model ◽  
Standard Uncertainty ◽  
X Ray ◽  
Error Bars ◽  
New Framework

AbstractThis is the first in a series of articles which present a new framework for computing the standard uncertainty in electron excited X-ray microanalysis measurements. This article will discuss the framework and apply it to a handful of simple, but useful, subcomponents of the larger problem. Subsequent articles will handle more complex aspects of the measurement model. The result will be a framework in which sophisticated and practical models of the uncertainty for real-world measurements. It will include many long overlooked contributions like surface roughness and coating thickness. The result provides more than just error bars for our measurements. It also provides a framework for measurement optimization and, ultimately, the development of an expert system to guide both the novice and expert to design more effective measurement protocols.

Characteristic properties of AlTiN and TiN coated HSS materials

2015 ◽  
Vol 67 (2) ◽  
pp. 172-180 ◽  
Author(s):  
Mumin Sahin ◽  
Cenk Misirli ◽  
Dervis Özkan
Keyword(s):  
Surface Roughness ◽  
Tensile Strength ◽  
High Speed ◽  
Cutting Tools ◽  
High Speed Steel ◽  
Wear Properties ◽  
Content Type ◽  
X Ray ◽  
Number Of Cycles ◽  
Future Work

Purpose – The purpose of this paper is to examine mechanical and metallurgical properties of AlTiN- and TiN-coates high-speed steel (HSS) materials in detail. Design/methodology/approach – In this study, HSS steel parts have been processed through machining and have been coated with AlTiN and TiN on physical vapour deposition workbench at approximately 6,500°C for 4 hours. Tensile strength, fatigue strength, hardness tests for AlTiN- and TiN-coated HSS samples have been performed; moreover, energy dispersive X-ray spectroscopy and X-ray diffraction analysis and microstructure analysis have been made by scanning electron microscopy. The obtained results have been compared with uncoated HSS components. Findings – It was found that tensile strength of TiAlN- and TiN-coated HSS parts is higher than that of uncoated HSS parts. Highest tensile strength has been obtained from TiN-coated HSS parts. Number of cycles for failure of TiAlN- and TiN-coated HSS parts is higher than that for HSS parts. Particularly TiN-coated HSS parts have the most valuable fatigue results. However, surface roughness of fatigue samples may cause notch effect. For this reason, surface roughness of coated HSS parts is compared with that of uncoated ones. While the average surface roughness (Ra) of the uncoated samples was in the range of 0.40 μm, that of the AlTiN- and TiN-coated samples was in the range of 0.60 and 0.80 μm, respectively. Research limitations/implications – It would be interesting to search different coatings for cutting tools. It could be the good idea for future work to concentrate on wear properties of tool materials. Practical implications – The detailed mechanical and metallurgical results can be used to assess the AlTiN and TiN coating applications in HSS materials. Originality/value – This paper provides information on mechanical and metallurgical behaviour of AlTiN- and TiN-coated HSS materials and offers practical help for researchers and scientists working in the coating area.

LPG Synthesis from Syngas over Cu/ZnO-Pd-β Catalysts Prepared by Ultrasonic Spray Pyrolysis

2015 ◽  
Vol 659 ◽  
pp. 252-256
Author(s):  
Sudarat Chaiwatyothin ◽  
Wittawat Ratanathavorn ◽  
Tharapong Vitidsant ◽  
Prasert Reubroycharoen
Keyword(s):  
Spray Pyrolysis ◽  
Fixed Bed ◽  
Ultrasonic Spray Pyrolysis ◽  
Product Distribution ◽  
Fixed Bed Reactor ◽  
Spherical Particles ◽  
Gaseous State ◽  
X Ray ◽  
Ultrasonic Spray ◽  
Co Conversion

Synthesis of nanoCu/ZnO catalyst for LPG production was prepared by ultrasonic spray pyrolysis (USP). Hollow spherical particles were obtained by USP technique using an aqueous solution of Cu (NO3)3.6H2O and Zn (NO3)3.3H2O with different concentration of 0.05, 0.1 and 0.5 molar under the pyrolysis temperatures of 600, 700 and 800°C. Mists of the solution were generated from the precursor solution by ultra sonic vibrators at frequency of ~1.7 MHz. The physicochemical properties of catalysts were characterized by X-ray diffraction, temperature-programmed reduction, scanning electron microscope, nitrogen adsorption-desorption, and energy dispersive X-ray spectrometer. The results showed that increasing in precursor concentration resulted in a large particle and particles size distributed in a range of 0.63-1.21 μm. Particles prepared at pyrolysis temperature 700°C exhibited homogeneous in size and shape compared to other temperature. The catalytic activity of nanoCu/ZnO-Pd-β catalysts was performed in a fixed-bed reactor for synthesizing LPG. The reaction took place at 260°C, 3.0 MPa, and the ratio of H2/CO = 2/1. All the products from the reactor were in gaseous state, and analyzed by on-line gas chromatography. The results showed that %CO conversion was high but decreased rapidly with increasing reaction time. Cu/ZnO catalyst prepared by co-precipitation gave higher %CO conversion than that prepared by ultrasonic spray pyrolysis. Moreover, hydrocarbon product distribution for Cu/ZnO catalyst produced at concentration 0.1 M 700°C by ultrasonic spray pyrolysis gave the highest LPG selectivity.

Self-avoiding random walk: A Brownian motion model with local time drift

1987 ◽  
Vol 74 (2) ◽  
pp. 271-287 ◽  
Author(s):  
J. R. Norris ◽  
L. C. G. Rogers ◽  
David Williams
Keyword(s):  
Brownian Motion ◽  
Random Walk ◽  
Local Time ◽  
Motion Model ◽  
Time Drift ◽  
Brownian Motion Model
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