scholarly journals Exploring the structures, stability, and light absorption properties of three thiostannates synthesised at similar conditions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Henrik S. Jeppesen ◽  
Peter Nørby ◽  
Jens Jakob Gammelgaard ◽  
Kasper Borup ◽  
Nina Lock
Keyword(s):  
Thermal Stability ◽  
Thermal Treatment ◽  
Light Absorption ◽  
Structural Changes ◽  
Function Analysis ◽  
Layered Compounds ◽  
Organic Cations ◽  
Absorption Properties ◽  
Structure Directing Agent ◽  
Cation Order

AbstractWe present the synthesis, crystal structures and optical properties of three thiostannates prepared by using 1-(2-aminoethyl)piperazine (AEPz) as structure directing agent. Two of the thiostannates are layered materials (AEPz-SnS-1 and AEPz:EtOH-SnS-1) consisting of [Sn3S72−]n sheets with organic cations located in-between. The third compound is a molecular thiostannate (Sn2S6(AEPzH2)2) composed of dimeric Sn2S64− and AEPzH22+. In preparation of the layered compounds, the use of AEPz as the only solvent results in AEPz-SnS-1 with regular hexagonal pores and crystallographically disordered organic cations. In contrast, a mixture of AEPz and absolute ethanol gives AEPz:EtOH-SnS-1 with distorted hexagonal pores and ordered cations between the layers. The influence of cation order on the light absorption properties and the material thermal stability was investigated through thermal treatment of the layered compounds up to 200 °C. Both compounds show colour changes when heated, but cation order results in larger thermal stability. For AEPz-SnS-1, a decreased inter-layer distance and substantial loss of organic matter was observed when heated. However, pair distribution function analysis reveals that the local in-layer thiostannate structure of AEPz-SnS-1 remains unchanged. In contrast, AEPz:EtOH-SnS-1 does not undergo noticeable structural changes by the thermal treatment. All materials are optical semiconductors with band gaps of 3.0–3.1 eV.

Structural Changes of TiO2 as a Result of Irradiation by E-Beam and X-Rays

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Perica Paunović ◽  
Anita Grozdanov ◽  
Petre Makreski ◽  
Gennaro Gentile
Keyword(s):  
Thermal Stability ◽  
Raman Spectroscopy ◽  
Photocatalytic Activity ◽  
Thermal Treatment ◽  
Structural Changes ◽  
Sol Gel ◽  
X Rays ◽  
Beam Irradiation ◽  
X Ray ◽  
The Subject

Abstract The subject of this research was to monitor and evaluate the effect of X-rays and e-beam irradiation on the structure of nanoscaled TiO2 and its properties. The samples of nanoscaled TiO2 were synthesized using the sol–gel method and subsequently exposed to thermal treatment to obtain the anatase crystalline structure. X-ray powder diffraction (XRPD) and Raman spectroscopy revealed the following changes in the structure as a result of the e-beam and X-ray irradiation: a decrease in the size of the crystallite of TiO2, an increase of the distance between the crystalline planes and the lattice parameters as well as the achievement of a certain degree of amorphization. As a consequence of the structural changes, thermal stability decreased. Also, a shift of the light absorption toward the visible end of the spectrum was detected and the energy of the band gap was reduced, indicating a better photocatalytic activity, i.e., the photocatalytic action can be shifted to the region of the visible light.

scholarly journals Stability Study of Erythritol as Phase Change Material for Medium Temperature Thermal Applications

2021 ◽  
Vol 11 (12) ◽  
pp. 5448
Author(s):  
Mayra Paulina Alferez Luna ◽  
Hannah Neumann ◽  
Stefan Gschwander
Keyword(s):  
Thermal Stability ◽  
Thermal Treatment ◽  
Phase Change ◽  
Latent Heat ◽  
Structural Changes ◽  
Stability Study ◽  
Sugar Alcohols ◽  
Scanning Calorimetry ◽  
Medium Temperature ◽  
Good Thermal Stability

Sugar alcohols belong to a promising category of organic phase change materials (PCM) because of their high latent heat and density compared to other PCM. However, some sugar alcohols have shown latent heat degradation when heated above their melting temperature. Most of the available studies report the structural changes of erythritol during cycling rather than its thermal stability at constant temperature. This study aimed to assess the effect of thermal treatment on erythritol thermal, chemical and physical properties, as well as to find means to enhance its thermal stability. Erythritol and its mixtures with antioxidant were heated and maintained at different temperatures above its melting point. Erythritol was analyzed before and after thermal treatment via Fourier-transform infrared spectroscopy and differential scanning calorimetry. It was suggested that the degradation of latent heat follows a first order reaction. Mixtures of erythritol with antioxidant had a lower degradation rate compared to pure erythritol under air. Sample browning was observed along the heating treatment of mainly pure erythritol. Antioxidant was found to help to reduce erythritol degradation. No chemical composition changes were detected in samples under argon atmosphere and overall good thermal stability was found throughout the testing period.

scholarly journals Computational Methods for Structure-to-Function Analysis of Diet-Derived Catechins-Mediated Targeting of In Vitro Vasculogenic Mimicry

2021 ◽  
Vol 20 ◽  
pp. 117693512110092
Author(s):  
Abicumaran Uthamacumaran ◽  
Narjara Gonzalez Suarez ◽  
Abdoulaye Baniré Diallo ◽  
Borhane Annabi
Keyword(s):  
Machine Learning ◽  
Cancer Cells ◽  
Structural Changes ◽  
Function Analysis ◽  
Vasculogenic Mimicry ◽  
Machine Learning Algorithms ◽  
Emergent Behavior ◽  
Molecular Signature ◽  
Ovarian Cancer Cells

Background: Vasculogenic mimicry (VM) is an adaptive biological phenomenon wherein cancer cells spontaneously self-organize into 3-dimensional (3D) branching network structures. This emergent behavior is considered central in promoting an invasive, metastatic, and therapy resistance molecular signature to cancer cells. The quantitative analysis of such complex phenotypic systems could require the use of computational approaches including machine learning algorithms originating from complexity science. Procedures: In vitro 3D VM was performed with SKOV3 and ES2 ovarian cancer cells cultured on Matrigel. Diet-derived catechins disruption of VM was monitored at 24 hours with pictures taken with an inverted microscope. Three computational algorithms for complex feature extraction relevant for 3D VM, including 2D wavelet analysis, fractal dimension, and percolation clustering scores were assessed coupled with machine learning classifiers. Results: These algorithms demonstrated the structure-to-function galloyl moiety impact on VM for each of the gallated catechin tested, and shown applicable in quantifying the drug-mediated structural changes in VM processes. Conclusions: Our study provides evidence of how appropriate 3D VM compression and feature extractors coupled with classification/regression methods could be efficient to study in vitro drug-induced perturbation of complex processes. Such approaches could be exploited in the development and characterization of drugs targeting VM.

scholarly journals Zn(ferulate)-LSH Systems as Multifunctional Filters

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2349
Author(s):  
Gustavo Pereira Saito ◽  
Ana Carolina Lanfredi Matsumoto ◽  
Renata Pires Assis ◽  
Iguatemy Lourenço Brunetti ◽  
Marco Aurélio Cebim ◽  
...  
Keyword(s):  
Structural Changes ◽  
Reactive Species ◽  
Layered Compounds ◽  
Human Organism ◽  
Metal Hydroxides ◽  
Spectroscopic Analyses ◽  
Carboxylate Groups ◽  
Constant Ph ◽  
Solar Radiation Exposure

Excessive UV solar radiation exposure causes human health risks; therefore, the study of multifunctional filters is important to skin UV protective ability and also to other beneficial activities to the human organism, such as reduction of reactive oxygen species (ROS) responsible for cellular damages. Potential multifunctional filters were obtained by intercalating of ferulate anions into layered simple metal hydroxides (LSH) through anion exchange and precipitation at constant pH methods. Ultrasound treatment was used in order to investigate the structural changes in LSH-ferulate materials. Structural and spectroscopic analyses show the formation of layered materials composed by a mixture of LSH intercalated with ferulate anions, where carboxylate groups of ferulate species interact with LSH layers. UV-VIS absorption spectra and in vitro SPF measurements indicate that LSH-ferulate systems have UV shielding capacity, mainly UVB protection. The results of reactive species assays show the ability of layered compounds in capture DPPH•, ABTS•+, ROO•, and HOCl/OCl− reactive species. LSH-ferulate materials exhibit antioxidant activity and singular optical properties that enable their use as multifunctional filters.

scholarly journals Light-induced levitation of ultralight carbon aerogels via temperature control

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Reo Yanagi ◽  
Ren Takemoto ◽  
Kenta Ono ◽  
Tomonaga Ueno
Keyword(s):  
Carbon Nanotubes ◽  
Heat Capacity ◽  
Porous Materials ◽  
Temperature Control ◽  
Light Absorption ◽  
Carbon Aerogel ◽  
Carbon Aerogels ◽  
Halogen Lamp ◽  
Absorption Properties ◽  
Air Density

AbstractWe demonstrate that ultralight carbon aerogels with skeletal densities lesser than the air density can levitate in air, based on Archimedes' principle, when heated with light. Porous materials, such as aerogels, facilitate the fabrication of materials with density less than that of air. However, their apparent density increases because of the air inside the materials, and therefore, they cannot levitate in air under normal conditions. Ultralight carbon aerogels, fabricated using carbon nanotubes, have excellent light absorption properties and can be quickly heated by a lamp owing to their small heat capacity. In this study, an ultralight carbon aerogel was heated with a halogen lamp and levitated in air by expanding the air inside as well as selectively reducing its density. We also show that the levitation of the ultralight carbon aerogel can be easily controlled by turning the lamp on and off. These findings are expected to be useful for various applications of aerogels, such as in communication and transportation through the sky.

Enhanced thermal stability and lifetime of epoxy nanocomposites using covalently functionalized clay: experimental and modelling

2015 ◽  
Vol 39 (3) ◽  
pp. 2269-2278 ◽  
Author(s):  
Omid Zabihi ◽  
Hamid Khayyam ◽  
Bronwyn L. Fox ◽  
Minoo Naebe
Keyword(s):  
Thermal Stability ◽  
Thermal Degradation ◽  
Structural Changes ◽  
Epoxy Nanocomposites ◽  
Degradation Model ◽  
Different Types

Relationship between thermal degradation model of epoxy nanocomposites containing different types of modified nanoclay and their structural changes is explained.

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