Pair Plasma in Super-QED Magnetic Fields and the Hard X-Ray/Optical Emission of Magnetars

The effects of Mg and Zn dopants on the catalytic performance of Pt/Al2O3 catalyst were investigated for dehydrogenation of perhydrodibenzyltoluene (H18-DBT) as a liquid organic hydrogen carrier. Al2O3 supports were modified with Mg and Zn to produce Mg-Al2O3 and Zn-Al2O3 with a target loading of 3.8 wt.% for dopants. The modified supports were impregnated with chloroplatinic acid solution to produce the catalysts Pt/Al2O3, Pt/Mg-Al2O3 and Pt/Zn-Al2O3 of 0.5 wt.% Pt loading. Thereafter, the catalysts were characterised using inductively coupled plasma- optical emission spectrometry, scanning electron microscopy-energy dispersive X-ray spectroscopy, hydrogen temperature-programmed reduction, carbon-monoxide pulse chemisorption, ammonia temperature-programmed desorption, X-ray diffraction and transmission electron microscopy. The dehydrogenation experiments were performed using a horizontal plug flow reactor system and the catalyst time-on-stream was 22 h. Pt/Mg-Al2O3 showed the highest average hydrogen flowrate of 29 nL/h, while an average of 27 nL/h was obtained for both Pt/Al2O3 and Pt/Zn-Al2O3. This has resulted in a hydrogen yield of 80% for Pt/Mg-Al2O3, 71% for Pt/Zn-Al2O3 and 73% for Pt/Al2O3. In addition, the conversion of H18-DBT ranges from 99% to 92%, Pt 97–90% and 96–90% for Pt/Mg-Al2O3, Pt/Zn-Al2O3 and Pt/Al2O3, respectively. Following the latter catalyst order, the selectivity to dibenzyltoluene (H0-DBT) ranges from 78% to 57%, 75–51% and 71–45%. Therefore, Pt/Mg-Al2O3 showed improved catalytic performance towards dehydrogenation of H18-DBT.

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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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Theoretical and experimental investigation of point defects in cubic boron nitride

MRS Advances ◽

10.1557/adv.2017.53 ◽

2017 ◽

Vol 2 (29) ◽

pp. 1545-1550 ◽

Cited By ~ 1

Author(s):

Nicholas L. McDougall ◽

Jim G. Partridge ◽

Desmond W. M. Lau ◽

Philipp Reineck ◽

Brant C. Gibson ◽

...

Keyword(s):

Boron Nitride ◽

Cubic Boron Nitride ◽

Optical Emission ◽

Wide Band ◽

Wide Band Gap ◽

Edge Structure ◽

X Ray ◽

Substitutional Defects ◽

X Ray Absorption ◽

Annealing Experiments

ABSTRACTCubic boron nitride (cBN) is a synthetic wide band gap material that has attracted attention due to its high thermal conductivity, optical transparency and optical emission. In this work, defects in cBN have been investigated using experimental and theoretical X-ray absorption near edge structure (XANES). Vacancy and O substitutional defects were considered, with O substituted at the N site (ON) to be the most energetically favorable. All defects produce unique signatures in either the B or N K-edges and can thus be identified using XANES. The calculations coupled with electron-irradiation / annealing experiments strongly suggest that ON is the dominant defect in irradiated cBN and remains after annealing. This defect is a likely source of optical emission in cBN.

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Corrosion Behaviours of Mo Modified Ti6Al4V Alloy in Hank’s Solution

Materials Science Forum ◽

10.4028/www.scientific.net/msf.610-613.1150 ◽

2009 ◽

Vol 610-613 ◽

pp. 1150-1154

Author(s):

Ai Lan Fan ◽

Cheng Gang Zhi ◽

Lin Hai Tian ◽

Lin Qin ◽

Bin Tang

Keyword(s):

Electrochemical Corrosion ◽

Optical Emission ◽

Ti6al4v Alloy ◽

X Ray Diffraction ◽

X Ray ◽

Diffusion Layers ◽

Modified Layer ◽

Surface Modified ◽

Hank’S Solution ◽

And Diffusion

The Mo surface modified layer on Ti6Al4V alloy was obtained by the plasma surface alloying technique. The structure and composition of the Mo modified Ti6Al4V alloy was investigated by X-ray diffraction (XRD) and glow discharge optical emission spectroscopy (GDOES). The Mo modified layer contains Mo coating on subsurface and diffusion layers between the subsurface and substrate. The X- ray diffraction analysis of the Mo modified Ti6Al4V alloy reveals that the outmost surface of the Mo modified Ti6Al4V alloy is composed of pure Mo. The electrochemical corrosion performance of the Mo modified Ti6Al4V alloy in 25°C Hank’s solution was investigated and compared with that of Ti6Al4V alloy. Results indicate that the self-corroding electric potential and the corrosion-rate of the Mo modified Ti6Al4V alloy are higher than that of Ti6Al4V alloy in 25°C Hank’s solution.

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Using SEM-EDX and ICP-OES to Investigate the Elemental Composition of Green MacroalgaVaucheria sessilis

The Scientific World JOURNAL ◽

10.1155/2014/891928 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8 ◽

Cited By ~ 12

Author(s):

Izabela Michalak ◽

Krzysztof Marycz ◽

Katarzyna Basińska ◽

Katarzyna Chojnacka

Keyword(s):

Elemental Composition ◽

Cross Section ◽

Inductively Coupled Plasma ◽

Algal Biomass ◽

Optical Emission Spectroscopy ◽

Optical Emission ◽

Icp Oes ◽

X Ray ◽

Inductively Coupled ◽

Analytical System

The biomass ofVaucheria sessilisforms algal mats in many freshwaters. There is a need to find the method of algal biomass utilization.Vaucheria sessilisis a rich source of micro- and macronutrients and can be used as a soil amendment. In the paper, the elemental composition of enriched, via bioaccumulation process, macroalga was investigated. For this purpose, two independent techniques were used: scanning electron microscopy with an energy dispersive X-ray analytical system (SEMEDX) and inductively coupled plasma optical emission spectroscopy (ICP-OES). The biomass was exposed to two microelemental solutions, with Cu(II) and Zn(II) ions. After two weeks of the experiment, macroalga accumulated 98.5 mg of Zn(II) ions in 1 g of dry biomass and 68.9 mg g−1of Cu(II) ions. Micrographs performed by SEM proved that bioaccumulation occurred. Metal ions were bound on the surface and in the interior of cells. Mappings of all cations showed that in the case of the surface of biomass (biosorption), the elements constituted aggregations and in the case of the cross section (bioaccumulation) they were evenly distributed. The algal biomass with permanently bound microelements can find an application in many branches of the industry (feed, natural fertilizers, etc.).

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Single shot x-ray diffractometry in SACLA with pulsed magnetic fields up to 16 T

Physical Review Research ◽

10.1103/physrevresearch.2.043175 ◽

2020 ◽

Vol 2 (4) ◽

Author(s):

Akihiko Ikeda ◽

Yasuhiro H. Matsuda ◽

Xuguang Zhou ◽

Takeshi Yajima ◽

Yuya Kubota ◽

...

Keyword(s):

Magnetic Fields ◽

Single Shot ◽

Pulsed Magnetic Fields ◽

X Ray

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The Magnetic Fields of Anomalous X-ray Pulsars

10.1063/1.2900155 ◽

2008 ◽

Cited By ~ 2

Author(s):

Feryal Özel ◽

Tolga Güver ◽

Ersin Göğüş ◽

C. Bassa ◽

Z. Wang ◽

...

Keyword(s):

Magnetic Fields ◽

X Ray

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Investigating the Magnetospheres of Rapidly Rotating B-type Stars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317002812 ◽

2016 ◽

Vol 12 (S329) ◽

pp. 369-372

Author(s):

C. L. Fletcher ◽

V. Petit ◽

Y. Nazé ◽

G. A. Wade ◽

R. H. Townsend ◽

...

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Centrifugal Force ◽

Point Of View ◽

Closed Field ◽

Theoretical Point ◽

X Rays ◽

Rapid Rotation ◽

X Ray ◽

Surface Magnetic Field

AbstractRecent spectropolarimetric surveys of bright, hot stars have found that ~10% of OB-type stars contain strong (mostly dipolar) surface magnetic fields (~kG). The prominent paradigm describing the interaction between the stellar winds and the surface magnetic field is the magnetically confined wind shock (MCWS) model. In this model, the stellar wind plasma is forced to move along the closed field loops of the magnetic field, colliding at the magnetic equator, and creating a shock. As the shocked material cools radiatively it will emit X-rays. Therefore, X-ray spectroscopy is a key tool in detecting and characterizing the hot wind material confined by the magnetic fields of these stars. Some B-type stars are found to have very short rotational periods. The effects of the rapid rotation on the X-ray production within the magnetosphere have yet to be explored in detail. The added centrifugal force due to rapid rotation is predicted to cause faster wind outflows along the field lines, leading to higher shock temperatures and harder X-rays. However, this is not observed in all rapidly rotating magnetic B-type stars. In order to address this from a theoretical point of view, we use the X-ray Analytical Dynamical Magnetosphere (XADM) model, originally developed for slow rotators, with an implementation of new rapid rotational physics. Using X-ray spectroscopy from ESA’s XMM-Newton space telescope, we observed 5 rapidly rotating B-types stars to add to the previous list of observations. Comparing the observed X-ray luminosity and hardness ratio to that predicted by the XADM allows us to determine the role the added centrifugal force plays in the magnetospheric X-ray emission of these stars.

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