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 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.

scholarly journals Dynamics of Microbial Inactivation and Acrylamide Production in High-Temperature Heat Treatments

Foods ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2535
Author(s):  
Jose Lucas Peñalver-Soto ◽  
Alberto Garre ◽  
Arantxa Aznar ◽  
Pablo S. Fernández ◽  
Jose A. Egea
Keyword(s):  
High Temperature ◽  
Food Safety ◽  
High Temperatures ◽  
Processing Parameters ◽  
Temperature Treatment ◽  
Heat Treatments ◽  
Microbial Inactivation ◽  
Point Of View ◽  
High Temperature Treatment ◽  
Microbiological Safety

In food processes, optimizing processing parameters is crucial to ensure food safety, maximize food quality, and minimize the formation of potentially toxigenic compounds. This research focuses on the simultaneous impacts that severe heat treatments applied to food may have on the formation of harmful chemicals and on microbiological safety. The case studies analysed consider the appearance/synthesis of acrylamide after a sterilization heat treatment for two different foods: pureed potato and prune juice, using Geobacillus stearothermophilus as an indicator. It presents two contradictory situations: on the one hand, the application of a high-temperature treatment to a low acid food with G. stearothermophilus spores causes their inactivation, reaching food safety and stability from a microbiological point of view. On the other hand, high temperatures favour the appearance of acrylamide. In this way, the two objectives (microbiological safety and acrylamide production) are opposed. In this work, we analyse the effects of high-temperature thermal treatments (isothermal conditions between 120 and 135 °C) in food from two perspectives: microbiological safety/stability and acrylamide production. After analysing both objectives simultaneously, it is concluded that, contrary to what is expected, heat treatments at higher temperatures result in lower acrylamide production for the same level of microbial inactivation. This is due to the different dynamics and sensitivities of the processes at high temperatures. These results, as well as the presented methodology, can be a basis of analysis for decision makers to design heat treatments that ensure food safety while minimizing the amount of acrylamide (or other harmful substances) produced.

scholarly journals Phosphoproteomic analysis of lettuce (Lactuca sativa L.) reveals starch and sucrose metabolism functions during bolting induced by high temperature

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0244198
Author(s):  
Xiaoxiao Qin ◽  
Panpan Li ◽  
Shaowei Lu ◽  
Yanchuan Sun ◽  
Lifeng Meng ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Lactuca Sativa ◽  
Molecular Mechanisms ◽  
Soluble Sugar ◽  
High Temperature Stress ◽  
Temperature Treatment ◽  
Sucrose Metabolism ◽  
High Temperature Treatment ◽  
Lactuca Sativa L

High temperatures induce early bolting in lettuce (Lactuca sativa L.), which decreases both quality and production. However, knowledge of the molecular mechanism underlying high temperature promotes premature bolting is lacking. In this study, we compared lettuce during the bolting period induced by high temperatures (33/25 °C, day/night) to which raised under controlled temperatures (20/13 °C, day/night) using iTRAQ-based phosphoproteomic analysis. A total of 3,814 phosphorylation sites located on 1,766 phosphopeptides from 987 phosphoproteins were identified after high-temperature treatment,among which 217 phosphoproteins significantly changed their expression abundance (116 upregulated and 101 downregulated). Most phosphoproteins for which the abundance was altered were associated with the metabolic process, with the main molecular functions were catalytic activity and transporter activity. Regarding the functional pathway, starch and sucrose metabolism was the mainly enriched signaling pathways. Hence, high temperature influenced phosphoprotein activity, especially that associated with starch and sucrose metabolism. We suspected that the lettuce shorten its growth cycle and reduce vegetative growth owing to changes in the contents of starch and soluble sugar after high temperature stress, which then led to early bolting/flowering. These findings improve our understanding of the regulatory molecular mechanisms involved in lettuce bolting.

scholarly journals Green coconut fiber thermal behaviour under the presence of a cobalt spinel catalyst

2018 ◽  
Vol 1 (4) ◽  
Author(s):  
Felipe Z. R Monteiro1 ◽  
Rogério N. C. Siqueira1 ◽  
Francisco J. Moura1 ◽  
Alexandre V. Grillo2
Keyword(s):  
High Pressures ◽  
Raw Materials ◽  
Degradation Kinetics ◽  
Kinetic Modelling ◽  
Spinel Phase ◽  
Inert Atmosphere ◽  
X Ray Diffraction ◽  
Coconut Fiber ◽  
Cobalt Spinel ◽  
Synthesized Materials

With increasing environmental concerns, much effort has been spent in research regarding development of sustainable processes for production of fuels and chemical products. In this context, hydrothermal liquefaction (HTL) has gained increasing attention, as a possible route for the chemical transformation of organic raw-materials, some sort of biomass, for example, into liquid oils at temperatures usually below 400°C, under moderate to high pressures (5 - 25 MPa), usually in the presence of a suitable catalyst. In the present work the thermogravimetric (TG) behavior under inert atmosphere of pure green coconut fiber and mixtures thereof with a spinel phase (Fe2CoO4), acting as catalyst has been studied. Spinel samples have been produced at 1000°C and different calcination times (3h, 6h and 9h). Both raw and synthesized materials were characterized  through different techniques, such as scanning electron microscopy (SEM), X-ray diffraction (XRD) and Infrared Absorption Spectroscopy (FTIR). According to the TG data, the catalyst produced during a calcination time of 9h showed a superior behavior regarding the lignin full thermal decomposition, which developed without fixed carbon formation. The results further suggest that the mixing process has a significant effect over the measured degradation kinetics, as it has a direct influence over the contact between catalyst and fibers. The kinetic modelling applied to the dynamic TG signal allowed a quantitative representation of the experimental data. The global process activation energy and order have proven to be respectively, 85.291 kJ / mol and 0.1227.

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.

Superconductivity in SmFeAsO0.8F 0.2 Synthesized by High Pressure High Temperature Treatment

2011 ◽  
Vol 197-198 ◽  
pp. 499-502
Author(s):  
Zheng He Hua ◽  
Heng Zhang ◽  
Ju Peng
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Electrical Transport ◽  
Upper Critical Field ◽  
Magnetic Field Effect ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
X Ray Diffraction ◽  
High Pressure High Temperature ◽  
High Transition

Superconducting SmFeAsO0.8F0.2 compound was successfully synthesized by high pressure high temperature treatment with pressure of 6 G Pa at 1400 °C for 2 hours. The X-ray diffraction pattern of the sample indicates the formation of the tetragonal ZrCuSiAs-type SmFeAsO0.8F0.2 with lattice parameters a=3.932 Å and c=8.490 Å. The electrical transport study shows that the sample has a rather high transition temperature Tc of about 52 K, and magnetic field effect on the resistance reveals a rather high upper critical field HC2 of about 65 T.

The high-pressure phase of CePtAl

2017 ◽  
Vol 72 (1) ◽  
pp. 77-82 ◽  
Author(s):  
Gunter Heymann ◽  
Birgit Heying ◽  
Ute Ch. Rodewald ◽  
Oliver Janka
Keyword(s):  
High Pressure ◽  
Magnetic Ordering ◽  
Structure Type ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
X Ray Diffraction ◽  
Aluminum Compound ◽  
Arc Melting ◽  
High Pressure High Temperature ◽  
Pressure Phase

AbstractThe intermetallic aluminum compound HP-CePtAl was synthesized by arc melting of the elements with subsequent high-pressure/high-temperature treatment at 1620 K and 10.5 GPa in a multianvil press. The compound crystallizes in the hexagonal MgZn2-type structure (P63/mmc) with lattice parameters of a=552.7(1) and c=898.8(2) pm refined from powder X-ray diffraction data. With the help of single crystal investigations (wR=0.0527, 187 F2 values, 13 variables), the proposed structure type was confirmed and the mixed Pt/Al site occupations could be refined. Magnetic susceptibility measurements showed a disappearance of the complex magnetic ordering phenomena, which are observed in NP-CePtAl.

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