scholarly journals A study of radicals in industrial raw cristobalite powders

2021 ◽  
Vol 48 (2) ◽  
Author(s):  
Francesco Di Benedetto ◽  
Andrea Giaccherini ◽  
Maurizio Romanelli ◽  
Giordano Montegrossi ◽  
Elena Belluso ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Raw Materials ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Energy Dispersive Microanalysis ◽  
Structural Coherence ◽  
Artificial Stone ◽  
Electron Paramagnetic

AbstractWe report the results of an experimental multianalytical characterisation of industrial cristobalite powders, used as raw materials for artificial stone production. Cristobalite is considered a serious threat to human health. The study was carried out through X-ray diffraction (XRD), scanning electron microscopy with energy dispersive microanalysis (SEM/EDS), continuous-wave (cw) and pulse electron paramagnetic resonance (EPR) spectroscopy. Our results point out a sub-micrometric size of the structural coherence in cristobalite, associated with numerous stacking defects. Moreover, the material was found characterised by the presence of superoxide radicals, whose persistence appears conceivably long. Radicals in a material synthesized through a high-temperature treatment were generated during the grinding step in the industrial production of cristobalite. During this process, in fact, both superoxide generation and structural defectivity are induced. Indeed, cristobalite powders already result activated by a radical population, before any kind of process in artificial stone production.

Passivation of Ge Nanocrystals in SiO2

2005 ◽  
Vol 108-109 ◽  
pp. 33-38 ◽  
Author(s):  
Jesper Skov Jensen ◽  
Tom P. Leervad Pedersen ◽  
Rui Pereira ◽  
Pia Bomholt ◽  
Jacques Chevallier ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Rutherford Backscattering Spectrometry ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Paramagnetic Resonance ◽  
Transmission Electron ◽  
Si Nanocrystals ◽  
Potential Applications ◽  
Electron Paramagnetic ◽  
Ge Nanocrystals

Nanocrystals have attracted considerable attention in recent years because of their potential applications as a light source in Si technology. From theory Ge nanocrystals are expected to have better luminescence properties than Si nanocrystals. In this study we have compared Ge nanocrystals produced both in PE-CVD deposited and magnetron sputtered SiO2 doped with Ge during deposition to concentrations between 3-9 at.%, followed by high temperature treatment at temperatures between 600 and 1100°C. The nanocrystals were structurally characterized by Rutherford backscattering spectrometry (RBS), transmission electron microscopy (TEM) and electron paramagnetic resonance (EPR). The interface of the nanocrystals was passivated by use of alnealing, while the effect of the passivation was monitored by photoluminescence (PL)

Solid - Phase Transformations of Anthracene in High Temperature Treatment

2012 ◽  
Vol 727-728 ◽  
pp. 1866-1871
Author(s):  
Luciana Lezira Pereira Almeida ◽  
Ana Lúcia Diegues Skury ◽  
R.S. Guimarães ◽  
Sérgio Neves Monteiro
Keyword(s):  
High Temperatures ◽  
High Pressures ◽  
Solid Phase ◽  
Raw Materials ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Synthesis Process ◽  
Diamond Synthesis ◽  
X Ray Diffraction ◽  
Xrd Techniques

The process of diamond synthesis using metal as a catalyst-solvent is a great method of industrial production by using high pressures and high temperatures. Several aromatic hydrocarbons are already studied for the process of graphitization of carbon, many have already been tried for use as raw materials for diamond synthesis. The graphitization of anthracene was carried out at a pressure of 3Gpa at a temperature of 1000°C. The graphite was produced in mixed Ni-Mn alloy for diamond synthesis process at a pressure of 4.5 GPa at a temperature of 500° to 1300°C. Scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques were used to characterize the transformation of graphite into diamond produced with anthracene starting at high pressures and high temperatures. The results of this study show that there is a diamond shape through an aromatic hydrocarbon at high pressures and temperatures with a catalyst-solvent process.

scholarly journals Electrospun Nanosystems Based on PHBV and ZnO for Ecological Food Packaging

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2123
Author(s):  
Maria Râpă ◽  
Maria Stefan ◽  
Paula Popa ◽  
Dana Toloman ◽  
Cristian Leostean ◽  
...  
Keyword(s):  
Food Packaging ◽  
Spin Trapping ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Hno3 Solution ◽  
X Ray ◽  
Trapping Method ◽  
Ft Ir ◽  
Doped Zno ◽  
Electron Paramagnetic

The electrospun nanosystems containing poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and 1 wt% Fe doped ZnO nanoparticles (NPs) (with the content of dopant in the range of 0–1 wt% Fe) deposited onto polylactic acid (PLA) film were prepared for food packaging application. They were investigated by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), antimicrobial analysis, and X-ray photoelectron spectrometry (XPS) techniques. Migration studies conducted in acetic acid 3% (wt/wt) and ethanol 10% (v/v) food simulants as well as by the use of treated ashes with 3% HNO3 solution reveal that the migration of Zn and Fe falls into the specific limits imposed by the legislation in force. Results indicated that the PLA/PHBV/ZnO:Fex electrospun nanosystems exhibit excellent antibacterial activity against the Pseudomonas aeruginosa (ATCC-27853) due to the generation of a larger amount of perhydroxyl (˙OOH) radicals as assessed using electron paramagnetic resonance (EPR) spectroscopy coupled with a spin trapping method.

scholarly journals Nanocrystalline composites in TiO2 and SnO2 system for ammonia resistance sensors

2018 ◽  
Vol 12 (3) ◽  
pp. 240-247
Author(s):  
Anna Szczygielska ◽  
Zbigniew Pędzich ◽  
Wojciech Maziarz
Keyword(s):  
Phase Composition ◽  
Sol Gel ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Medium Size ◽  
X Ray Diffraction ◽  
Nanocrystalline Tio2 ◽  
Tio2 Anatase ◽  
Transmission Electron ◽  
Sorption Method

This work describes the production of nanocrystalline TiO2 and SnO2 oxides, as well as their nanocomposites (containing 26.9, 58.7 and 79.0wt.% of SnO2) with two-stage sol-gel method combined with high temperature treatment. The phase composition and medium size crystallites were determined using X-ray diffraction analysis (XRD) and revealed that the nanocomposites crystallize in tetragonal structures of TiO2 - anatase and SnO2 - cassiterite. Specific surface area of the nanopowders, measured using sorption method (BET), changed from 42.1 to 160.8m2/g. The morphology of the nanopowders was observed using transmission electron microscope (TEM). As indicated by TEM images, the manufactured nanopowders were well crystallized and consisted of small, spherical grains. The obtained nanopowders were also tested for NH3 gas detection application. The presented method of nanopowders synthesis enables to obtain nanocrystalline TiO2 and SnO2 oxides, as well as composites from TiO2-SnO2 of known and controlled chemical and phase composition. It also enables to obtain composites used for gas sensors. The sensor made of composite containing 58.7wt.% of SnO2 exhibited the best NH3 sensing features.

Fabrication, characterization and magnetic properties of Na-doped ZnO nanorods

2016 ◽  
Vol 09 (03) ◽  
pp. 1650039 ◽  
Author(s):  
Jingyuan Piao ◽  
Li-Ting Tseng ◽  
Kiyonori Suzuki ◽  
Jiabao Yi
Keyword(s):  
Magnetic Measurements ◽  
Zno Nanorods ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Shallow Donors ◽  
Na Doping ◽  
Transmission Electron ◽  
Doped Zno ◽  
Electron Paramagnetic

Na-doped ZnO nanorods have been fabricated through a hydrothermal method. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses indicate that the d spacing of ZnO increases with increasing doping concentration, suggesting the effective incorporation of dopant Na in the samples. Electron paramagnetic resonance (EPR) measurements indicate that there are shallow donors in pure ZnO samples and the shallow donors are strongly prohibited by Na doping. In addition, the resonance at g = 2.005 suggests the formation of Zn vacancies. Magnetic measurements indicate that pure ZnO is paramagnetic and Na doping leads to ferromagnetism at room temperature. Moreover, 0.5% Na-doped ZnO nanorods exhibits the largest saturation magnetization.

scholarly journals An EPR Study on the Interaction between the Cu(I) Metal Binding Domains of ATP7B and the Atox1 Metallochaperone

2020 ◽  
Vol 21 (15) ◽  
pp. 5536
Author(s):  
Michael Zaccak ◽  
Zena Qasem ◽  
Lada Gevorkyan-Airapetov ◽  
Sharon Ruthstein
Keyword(s):  
Metal Binding ◽  
Continuous Wave ◽  
Regulation System ◽  
Membrane Domain ◽  
Paramagnetic Resonance ◽  
Copper Trafficking ◽  
Binding Domains ◽  
Metal Binding Domain ◽  
Pulsed Electron Paramagnetic Resonance ◽  
Electron Paramagnetic

Copper’s essentiality and toxicity mean it requires a sophisticated regulation system for its acquisition, cellular distribution and excretion, which until now has remained elusive. Herein, we applied continuous wave (CW) and pulsed electron paramagnetic resonance (EPR) spectroscopy in solution to resolve the copper trafficking mechanism in humans, by considering the route travelled by Cu(I) from the metallochaperone Atox1 to the metal binding domains of ATP7B. Our study revealed that Cu(I) is most likely mediated by the binding of the Atox1 monomer to metal binding domain 1 (MBD1) and MBD4 of ATP7B in the final part of its extraction pathway, while the other MBDs mediate this interaction and participate in copper transfer between the various MBDs to the ATP7B membrane domain. This research also proposes that MBD1-3 and MBD4-6 act as two independent units.

Sign in / Sign up

Export Citation Format

Share Document