scholarly journals Structural Changes in French VF Treatment Wetland Porous Media during the Rest Period: An Ex Situ Study Using X-ray Tomography

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 389
Author(s):  
German Dario Martinez-Carvajal ◽  
Laurent Oxarango ◽  
Jérôme Adrien ◽  
Pascal Molle ◽  
Nicolas Forquet
Keyword(s):  
Porous Media ◽  
Structural Changes ◽  
Rest Period ◽  
Treatment Wetlands ◽  
Ex Situ ◽  
Initial Value ◽  
Treatment Wetland ◽  
X Ray ◽  
The Impact ◽  
Deposit Layer

Clogging constitutes a major operational issue for treatment wetlands. The rest period is a key feature of French Vertical Flow (VF) treatment wetlands and serves to mitigate clogging. An ex-situ drying experiment was performed to mimic the rest period and record structural changes in the porous media using X-ray Computed Tomography (CT). Samples containing the deposit and gravel layers of a first stage French VF treatment wetland were extracted and left to dry in a control environment. Based on CT scans, three phases were identified (voids, biosolids, and gravels). The impact of the rest period was assessed by means of different pore-scale variables. Ultimately, the volume of biosolids had reduced to 58% of its initial value, the deposit layer thickness dropped to 68% of its initial value, and the void/biosolid specific surface area ratio increased from a minimum value of 1.1 to a maximum of 4.2. Cracks greater than 3 mm developed at the uppermost part of the deposit layer, while, in the gravel layer, the rise in void volume corresponds to pores smaller than 2 mm in diameter. Lastly, the air-filled microporosity is estimated to have increased by 0.11 v/v.

Size dependent behavior of Fe3O4crystals during electrochemical (de)lithiation: an in situ X-ray diffraction, ex situ X-ray absorption spectroscopy, transmission electron microscopy and theoretical investigation

2017 ◽  
Vol 19 (31) ◽  
pp. 20867-20880 ◽  
Author(s):  
David C. Bock ◽  
Christopher J. Pelliccione ◽  
Wei Zhang ◽  
Janis Timoshenko ◽  
K. W. Knehr ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
X Ray ◽  
Size Dependent ◽  
Transmission Electron ◽  
Dependent Behavior ◽  
X Ray Absorption

Crystal and atomic structural changes of Fe3O4upon electrochemical (de)lithiation were determined.

scholarly journals Influence of the Para-Substituent in Lanthanoid Complexes of Bistetrazole Substituted Calix[4]arenes

2019 ◽  
Author(s):  
Rene Z.H. Phe ◽  
Brian Skelton ◽  
Massimiliano Massi ◽  
Mark Ogden
Keyword(s):  
Structural Changes ◽  
Cluster Formation ◽  
Ammonium Cation ◽  
Ammonium Salts ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
X Ray ◽  
Mononuclear Complexes ◽  
Scattering Measurements ◽  
The Impact

5,11,17,23-Tetra-tert-butyl-25,27-dihydroxy-26,28-bis(tetrazole-5-ylmethoxy)calix[4]arene has been reported to form remarkable Ln19 and Ln12 elongated clusters, upon addition of aqueous ammonium carboxylates. The impact of the <i>para</i> substituent on lanthanoid cluster formation has been studied by synthesising two new bis-tetrazole calixarenes, with <i>p</i>-H, and <i>p</i>-allyl substituents. Solution phase dynamic light scattering measurements of the reaction mixtures indicated that clusters are not formed with the <i>p</i>-H and <i>p</i>-allyl derivatives, in contrast with the behaviour of the <i>t-</i>butyl analogue. Lanthanoid complexes of the <i>p</i>-H and <i>p</i>-allyl calixarenes were characterised by single crystal X-ray diffraction, and were found to form mononuclear complexes, linked to form a one-dimensional coordination polymer for the <i>p</i>-allyl system. All of the complexes were isolated as ammonium salts, with ammonium cation included in the calixarene cavity in most cases. It is concluded that the nature of the <i>para</i> substituent has a profound impact on the lanthanoid cluster formation process, and derivatives with more subtle structural changes will be required to determine if additional lanthanoid “bottlebrush” clusters can be isolated.<br><br>

scholarly journals Effect of Transitional Metals (Mn and Ni) Substitution in LiCoPO4 Olivines

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 601
Author(s):  
Oriele Palumbo ◽  
Jessica Manzi ◽  
Daniele Meggiolaro ◽  
Francesco M. Vitucci ◽  
Francesco Trequattrini ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Structural Changes ◽  
Transition Metal Ions ◽  
Xrd Analysis ◽  
Partial Substitution ◽  
Structural Alterations ◽  
X Ray ◽  
Transitional Metals ◽  
The Impact

Transition metal substitution is a key strategy to optimize the functional properties of advanced crystalline materials used as positive electrodes in secondary lithium batteries (LIBs). Here we investigate the structural alterations in the olivine lattice of Mn and Ni substituted LiCoPO4 phase and the impact on performance in LIBs. X-ray diffraction (XRD) and extended X-ray absorption experiments have been carried out in order to highlight the structural alterations induced by partial substitution of cobalt by manganese and nickel. XRD analysis suggests that substitution induces an expansion of the lattices and an increase of the antisite disorder between lithium and transition metal ions in the structure. XAS data highlight negligible electronic disorder but a relevant modulation in the local coordination around the different metal ions. Moreover, galvanostatic tests showed poor reversibility of the redox reaction compared to the pure LCP sample, and this failure is discussed in detail in view of the observed remarkable structural changes.

scholarly journals On the Beneficial Effect of MgCl2 as Electrolyte Additive to Improve the Electrochemical Performance of Li4Ti5O12 as Cathode in Mg Batteries

Nanomaterials ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 484 ◽  
Author(s):  
Marta Cabello ◽  
Gregorio Ortiz ◽  
Pedro Lavela ◽  
José Tirado
Keyword(s):  
Electrochemical Performance ◽  
Structural Changes ◽  
Surface Film ◽  
Practical Importance ◽  
Specific Capacity ◽  
Ex Situ ◽  
Insertion Reaction ◽  
Portable Devices ◽  
Active Electrode ◽  
X Ray

Magnesium batteries are a promising technology for a new generation of energy storage for portable devices. Attention should be paid to electrolyte and electrode material development in order to develop rechargeable Mg batteries. In this study, we report the use of the spinel lithium titanate or Li4Ti5O12 (LTO) as an active electrode for Mg2+-ion batteries. The theoretical capacity of LTO is 175 mA h g−1, which is equivalent to an insertion reaction with 1.5 Mg2+ ions. The ability to enhance the specific capacity of LTO is of practical importance. We have observed that it is possible to increase the capacity up to 290 mA h g−1 in first discharge, which corresponds to the reaction with 2.5 Mg2+ ions. The addition of MgCl2·6H2O to the electrolyte solutions significantly improves their electrochemical performance and enables reversible Mg deposition. Ex-situ X-ray diffraction (XRD) patterns reveal little structural changes, while X-ray photoelectron spectrometer (XPS) (XPS) measurements suggest Mg reacts with LTO. The Ti3+/Ti4+ ratio increases with the amount of inserted magnesium. The impedance spectra show the presence of a semicircle at medium-low frequencies, ascribable to Mg2+ ion diffusion between the surface film and LTO. Further experimental improvements with exhaustive control of electrodes and electrolytes are necessary to develop the Mg battery with practical application.

scholarly journals Thermal Stability and Radiation Tolerance of Lanthanide-Doped Cerium Oxide Nanocubes

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1369
Author(s):  
Kory Burns ◽  
Paris C. Reuel ◽  
Fernando Guerrero ◽  
Eric Lang ◽  
Ping Lu ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Ion Irradiation ◽  
Heavy Ion ◽  
Radiation Stability ◽  
Ex Situ ◽  
In Situ Tem ◽  
Free Standing ◽  
X Ray ◽  
High Fluences ◽  
The Impact

The thermal and radiation stability of free-standing ceramic nanoparticles that are under consideration as potential fillers for the improved thermal and radiation stability of polymeric matrices were investigated by a set of transmission electron microscopy (TEM) studies. A series of lanthanide-doped ceria (Ln:CeOx; Ln = Nd, Er, Eu, Lu) nanocubes/nanoparticles was characterized as synthesized prior to inclusion into the polymers. The Ln:CeOx were synthesized from different solution precipitation (oleylamine (ON), hexamethylenetetramine (HMTA) and solvothermal (t-butylamine (TBA)) routes. The dopants were selected to explore the impact that the cation has on the final properties of the resultant nanoparticles. The baseline CeOx and the subsequent Ln:CeOx particles were isolated as: (i) ON-Ce (not applicable), Nd (34.2 nm), Er (27.8 nm), Eu (42.4 nm), and Lu (287.4 nm); (ii) HMTA-Ce (5.8 nm), Nd (6.6 nm), Er (370.0 nm), Eu (340.6 nm), and Lu (287.4 nm); and (iii) TBA-Ce (4.1 nm), Nd (5.0 nm), Er (3.8 nm), Eu (7.3 nm), and Lu (3.8 nm). The resulting Ln:CeOx nanomaterials were characterized using a variety of analytical tools, including: X-ray fluorescence (XRF), powder X-ray diffraction (pXRD), TEM with selected area electron diffraction (SAED), and energy dispersive X-ray spectroscopy (EDS) for nanoscale elemental mapping. From these samples, the Eu:CeOx (ON, HMTA, and TBA) series were selected for stability studies due to the uniformity of the nanocubes. Through the focus on the nanoparticle properties, the thermal and radiation stability of these nanocubes were determined through in situ TEM heating and ex situ TEM irradiation. These results were coupled with data analysis to calculate the changes in size and aerial density. The particles were generally found to exhibit strong thermal stability but underwent amorphization as a result of heavy ion irradiation at high fluences.

Evaluate the Impact of Porous Media Structure on Soil Thermal Parameters Using X-Ray Computed Tomography

2020 ◽  
Vol 53 (12) ◽  
pp. 1752-1759
Author(s):  
A. Y. Mady ◽  
E. V. Shein ◽  
E. B. Skvortsova ◽  
K. N. Abrosimov
Keyword(s):  
Computed Tomography ◽  
Porous Media ◽  
Thermal Parameters ◽  
X Ray ◽  
X Ray Computed ◽  
The Impact ◽  
Soil Thermal Parameters

Experimental Investigations on the Tribological Performance of Electric Discharge Alloyed Ti–6Al–4V at 200–600 °C

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Jibin T. Philip ◽  
Deepak Kumar ◽  
Jose Mathew ◽  
Basil Kuriachen
Keyword(s):  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Wear Behavior ◽  
Ex Situ ◽  
Experimental Investigations ◽  
X Ray ◽  
Before And After ◽  
Xrd Techniques ◽  
Pin On Disk ◽  
The Impact

Abstract Nowadays, the titanium alloys observe broad applicability in aerospace, marine, automobile, and bio-medical industries due to their lightweight, bio-compatibility, good fatigue strength, and corrosion resistance. However, it possesses poor tribological behavior characterized by a high coefficient of friction (CoF) and the specific wear rate (SWR). In this paper, the impact of the electrical discharge machining on the tribological properties of Ti6Al4V (Ti64) was compared before and after electrical discharge machining (EDM) using a pin-on-disk tribometer under un-lubricated and ambient temperature. Besides, ex-situ analysis was performed on the distinct pin surfaces using (i) scanning electron microscopy (SEM), (ii) energy-dispersive X-ray spectroscopy (EDX), and (iii) X-ray diffraction spectroscopy (XRD) techniques to elucidate the associated wear mechanisms. The mechanical properties such as nano-hardness and elastic modulus of the test surfaces were also determined using a nano-indenter. Significant improvement in SWR (65.44% reduction) with a passable compromise for CoF (22.5% increment) occurred during experimentation (before and after EDM) at 100 N. Besides, the wear behavior of the electrical discharge alloyed Ti64 (ETi64) was evaluated at 200 °C, 400 °C, and 600 °C under the applied loads of 50–150 N. At 400 °C and 600 °C, the SWR initially decreased and then increased with variation in load from 50–100 N and 100–150 N, respectively. The enhanced tribo-behavior at 100 N was due to the protective influence of tribo-oxides, viz., TiO2 and Ti8O15 assisted by the hard Ti24C15 carbides in the recast layer (RL).

scholarly journals Structural Evolution of MoO3 Thin Films Deposited on Copper Substrates upon Annealing: An X-ray Absorption Spectroscopy Study

2019 ◽  
Vol 4 (2) ◽  
pp. 41 ◽  
Author(s):  
Macis ◽  
Rezvani ◽  
Davoli ◽  
Cibin ◽  
Spataro ◽  
...  
Keyword(s):  
Thin Films ◽  
Absorption Spectroscopy ◽  
Structural Changes ◽  
Structural Evolution ◽  
Ex Situ ◽  
Edge Structure ◽  
X Ray ◽  
High Gradients ◽  
Different Temperatures ◽  
X Ray Absorption

Structural changes of MoO3 thin films deposited on thick copper substrates upon annealing at different temperatures were investigated via ex situ X-Ray Absorption Spectroscopy (XAS). From the analysis of the X-ray Absorption Near-Edge Structure (XANES) pre-edge and Extended X-ray Absorption Fine Structure (EXAFS), we show the dynamics of the structural order and of the valence state. As-deposited films were mainly disordered, and ordering phenomena did not occur for annealing temperatures up to 300 °C. At ~350 °C, a dominant α-MoO3 crystalline phase started to emerge, and XAS spectra ruled out the formation of a molybdenum dioxide phase. A further increase of the annealing temperature to ~500 °C resulted in a complex phase transformation with a concurrent reduction of Mo6+ ions to Mo4+. These original results suggest the possibility of using MoO3 as a hard, protective, transparent, and conductive material in different technologies, such as accelerating copper-based devices, to reduce damage at high gradients.

Growth and Properties of Lattice Matched GaAsSbN Epilayer on GaAs for Solar Cell Applications

2005 ◽  
Vol 891 ◽  
Author(s):  
Sudhakar Bharatan ◽  
Shanthi Iyer ◽  
Kevin Matney ◽  
Ward J. Collis ◽  
Kalyan Nunna ◽  
...  
Keyword(s):  
Low Temperature ◽  
Structural Changes ◽  
Ex Situ ◽  
Rf Plasma ◽  
X Ray Diffraction ◽  
X Ray ◽  
Peak Energy ◽  
Localized Excitons ◽  
Matched Layers ◽  
Lattice Matched

ABSTRACTIn this work, the growth and characterization of GaAsSbN epilayers nearly lattice matched to GaAs, grown in an elemental solid source molecular beam epitaxy (MBE) system with a RF plasma nitrogen source, are discussed. The Sb and N compositions of the nearly lattice matched layers are 2.6% and 6.8%, respectively, as determined by high resolution x-ray diffraction (HRXRD) and secondary ion mass spectroscopy (SIMS) analysis. The layers are found to be fully strained as evidenced by the presence of Pendellosung fringes on the x-ray diffraction spectra.Effects of in-situ and ex-situ annealing on the low temperature photoluminescence (PL) characteristics are discussed. The 10 K PL peak energy of 1 eV with a FWHM of 18 meV has been achieved on ex-situ annealed samples in N ambient. The temperature dependence of PL peak energy exhibits “S-shaped” behavior in the low temperature regime, indicative of the presence of localized excitons. Raman spectroscopy analysis has been carried out to determine the local structural changes on annealing.

scholarly journals Influence of the Para-Substituent in Lanthanoid Complexes of Bistetrazole Substituted Calix[4]arenes

2019 ◽  
Author(s):  
Rene Z.H. Phe ◽  
Brian Skelton ◽  
Massimiliano Massi ◽  
Mark Ogden
Keyword(s):  
Structural Changes ◽  
Cluster Formation ◽  
Ammonium Cation ◽  
Ammonium Salts ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
X Ray ◽  
Mononuclear Complexes ◽  
Scattering Measurements ◽  
The Impact

5,11,17,23-Tetra-tert-butyl-25,27-dihydroxy-26,28-bis(tetrazole-5-ylmethoxy)calix[4]arene has been reported to form remarkable Ln19 and Ln12 elongated clusters, upon addition of aqueous ammonium carboxylates. The impact of the <i>para</i> substituent on lanthanoid cluster formation has been studied by synthesising two new bis-tetrazole calixarenes, with <i>p</i>-H, and <i>p</i>-allyl substituents. Solution phase dynamic light scattering measurements of the reaction mixtures indicated that clusters are not formed with the <i>p</i>-H and <i>p</i>-allyl derivatives, in contrast with the behaviour of the <i>t-</i>butyl analogue. Lanthanoid complexes of the <i>p</i>-H and <i>p</i>-allyl calixarenes were characterised by single crystal X-ray diffraction, and were found to form mononuclear complexes, linked to form a one-dimensional coordination polymer for the <i>p</i>-allyl system. All of the complexes were isolated as ammonium salts, with ammonium cation included in the calixarene cavity in most cases. It is concluded that the nature of the <i>para</i> substituent has a profound impact on the lanthanoid cluster formation process, and derivatives with more subtle structural changes will be required to determine if additional lanthanoid “bottlebrush” clusters can be isolated.<br><br>

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