scholarly journals Modeling of canonical and C2′-O-thiophenylmethyl modified hexamers of RNA. Insights into the nature of structural changes and thermal stability

2018 ◽  
Vol 42 (12) ◽  
pp. 10177-10183
Author(s):  
Yannick Kokouvi Dzowo ◽  
Carly Wolfbrandt ◽  
Marino J. E. Resendiz ◽  
Haobin Wang
Keyword(s):  
Thermal Stability ◽  
Structural Changes ◽  
Thermal Stabilization

Modification of the C2′-O-position with thiophenylmethyl groups on both strands leads to thermal stabilization of the duplex. Predicting the effects that modifications will have on structure of RNA is of importance in the development of new RNA technologies.

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.

Thermal Stabilization of Non-Stoichiometric GaAs through Beryllium Doping

1998 ◽  
Vol 510 ◽  
Author(s):  
R.C. Lutz ◽  
P. Specht ◽  
R. Zhao ◽  
S. Jeong ◽  
J. Bokor ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Carrier Lifetime ◽  
Thermal Stabilization ◽  
High Resistivity ◽  
X Ray Diffraction ◽  
Defect Band ◽  
Temperature Growth ◽  
Undoped Material ◽  
Strain Compensation ◽  
Beryllium Doping

AbstractBeryllium-doped, non-stoichiometric GaAs grown by MBE at low temperatures appears superior to its undoped counterpart in several key areas vital to device manufacturing. X-ray diffraction studies have indicated that material grown above 275°C shows complete thermal stability to annealing at temperatures up to 600°C. This behavior is ascribed in part to strain compensation between the small beryllium atoms and the large arsenic antisites. Consequently, outdiffusion of excess arsenic from the non-stoichiometric material into neighboring layers upon annealing or subsequent high temperature growth is expected to be negligible. Short carrier lifetime (<1 psec) and high resistivity (>104 Ω-cm) have been observed in the same as-grown material. Sub-picosecond lifetimes have been measured previously in undoped material, but the low growth temperatures required produce a supersaturation of antisites allowing for significant hopping conductivity through the defect band in as-grown material, and significant arsenic outdiffusion upon annealing. Due to electrical compensation of antisites by beryllium acceptors, materials in which the ionized antisites represent a major fraction of a relatively small total antisite concentration are now made possible by proceeding to higher growth temperatures. Thus, nonstoichiometric GaAs having a beneficial combination of thermal stability, short carrier lifetime and high resistivity can be fabricated

The role of glycosylation and domain interactions in the thermal stability of human angiotensin-converting enzyme

2008 ◽  
Vol 389 (9) ◽  
Author(s):  
Hester G. O'Neill ◽  
Pierre Redelinghuys ◽  
Sylva L.U. Schwager ◽  
Edward D. Sturrock
Keyword(s):  
Thermal Stability ◽  
Angiotensin Converting Enzyme ◽  
Physicochemical Properties ◽  
Mammalian Cells ◽  
Insect Cells ◽  
Thermal Stabilization ◽  
Site Directed Mutagenesis ◽  
Converting Enzyme ◽  
Complex Glycans ◽  
Thermal Stability Of

Abstract The N and C domains of somatic angiotensin-converting enzyme (sACE) differ in terms of their substrate specificity, inhibitor profiling, chloride dependency and thermal stability. The C domain is thermally less stable than sACE or the N domain. Since both domains are heavily glycosylated, the effect of glycosylation on their thermal stability was investigated by assessing their catalytic and physicochemical properties. Testis ACE (tACE) expressed in mammalian cells, mammalian cells in the presence of a glucosidase inhibitor and insect cells yielded proteins with altered catalytic and physicochemical properties, indicating that the more complex glycans confer greater thermal stabilization. Furthermore, a decrease in tACE and N-domain N-glycans using site-directed mutagenesis decreased their thermal stability, suggesting that certain N-glycans have an important effect on the protein's thermodynamic properties. Evaluation of the thermal stability of sACE domain swopover and domain duplication mutants, together with sACE expressed in insect cells, showed that the C domain contained in sACE is less dependent on glycosylation for thermal stabilization than a single C domain, indicating that stabilizing interactions between the two domains contribute to the thermal stability of sACE and are decreased in a C-domain-duplicating mutant.

scholarly journals Role of Ionic Headgroups on the Thermal, Rheological, and Foaming Properties of Novel Betaine-Based Polyoxyethylene Zwitterionic Surfactants for Enhanced Oil Recovery

Processes ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 908 ◽  
Author(s):  
Muhammad Shahzad Kamal ◽  
Syed Muhammad Shakil Hussain ◽  
Lionel Talley Fogang
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Oil Recovery ◽  
Structural Changes ◽  
Foam Stability ◽  
Foaming Properties ◽  
Zwitterionic Surfactants ◽  
Reservoir Conditions ◽  
Thermal Stability Of

Long-term thermal stability of surfactants under harsh reservoir conditions is one of the main challenges for surfactant injection. Most of the commercially available surfactants thermally degrade or precipitate when exposed to high-temperature and high-salinity conditions. In this work, we designed and synthesized three novel betaine-based polyoxyethylene zwitterionic surfactants containing different head groups (carboxybetaine, sulfobetaine, and hydroxysulfobetaine) and bearing an unsaturated tail. The impact of the surfactant head group on the long-term thermal stability, foam stability, and surfactant–polymer interactions were examined. The thermal stability of the surfactants was assessed by monitoring the structural changes when exposed at high temperature (90 °C) for three months using 1H-NMR, 13C-NMR, and FTIR analysis. All surfactants were found thermally stable regardless of the headgroup and no structural changes were evidenced. The surfactant–polymer interactions were dominant in deionized water. However, in seawater, the surfactant addition had no effect on the rheological properties. Similarly, changing the headgroup of polyoxyethylene zwitterionic surfactants had no major effect on the foamability and foam stability. The findings of the present study reveal that the betaine-based polyoxyethylene zwitterionic surfactant can be a good choice for enhanced oil recovery application and the nature of the headgroup has no major impact on the thermal, rheological, and foaming properties of the surfactant in typical harsh reservoir conditions (high salinity, high temperature).

scholarly journals Effects of aluminum sulfate soaking pretreatment on dimensional stability and thermostability of heat-treated wood

2020 ◽  
Author(s):  
Lijie Qu ◽  
Zhenyu Wang ◽  
Jing Qian ◽  
Zhengbin He ◽  
Songlin Yi
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Thermal Degradation ◽  
Structural Changes ◽  
Aluminum Sulfate ◽  
Treated Wood ◽  
Treatment Temperature ◽  
Chinese Fir ◽  
Heat Treated ◽  
Thermal Stability Of

Abstract Acidic aluminum sulfate hydrolysis solutions can be used to catalyze the thermal degradation of wood in a mild temperature environment, and thus reduce the temperature required for heat treatment process. To improve the dimensional and thermal stability of Chinese fir during heat treatment at 120 °C, 140 °C and 160 °C, this study investigated the effects of soaking pretreatment with 5%, 10% and 15% aluminum sulfate on the chemical and structural changes of the heat-treated Chinese fir. The results indicated that the samples treated at 15% aluminum sulfate concentration and 160 °C heat treatment achieved the best dimensional and thermal stability. Chemical analyses by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) indicated that the catalysis of aluminum sulfate resulted in degradation of hemicelluloses during the heat treatment, and an increase in the soaking concentration and heat treatment temperature also affected the thermal degradation of celluloses. The scanning electron microscope (SEM) and mass changes test results proved that the hydrolyzed aluminum flocs mainly adhered to the inner wall of the wood tracheid as spherical precipitates, and when the soaking concentration reached 10% and 15%, a uniform soaking effect could be achieved. The thermogravimetric (TG) analysis revealed the soaking pretreatment effectively improved the thermal stability of the heat-treated wood by physically wrapping and promoting the formation of a carbon layer on the wood surface during heat treatment. Thus, aluminum sulfate soaking pretreatment exerted a great effect on the dimensional and thermal stability of wood, allowing heat treatment to be performed at a lower temperature.

scholarly journals Effects of High Intensity Ultrasound on Physiochemical and Structural Properties of Goat Milk β-Lactoglobulin

Molecules ◽  
2020 ◽  
Vol 25 (16) ◽  
pp. 3637
Author(s):  
Xinhui Zhou ◽  
Cuina Wang ◽  
Xiaomeng Sun ◽  
Zixuan Zhao ◽  
Mingruo Guo
Keyword(s):  
Thermal Stability ◽  
Structural Properties ◽  
High Intensity ◽  
Structural Changes ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Goat Milk ◽  
High Intensity Ultrasound ◽  
Hydrophobicity Index ◽  
Β Lactoglobulin

This study aimed to compare the effects of high intensity ultrasound (HIU) applied at various amplitudes (20~40%) and for different durations (1~10 min) on the physiochemical and structural properties of goat milk β-lactoglobulin. No significant change was observed in the protein electrophoretic patterns by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Deconvolution and second derivative of the Fourier transform infrared spectra (FTIR) showed that the percentage of β-sheet of goat milk β-lactoglobulin was significantly decreased while those of α-helix and random coils increased after HIU treatment The surface hydrophobicity index and intrinsic fluorescence intensity of samples was enhanced and increased with increasing HIU amplitude or time. Differential scanning calorimetry (DSC) results exhibited that HIU treatments improved the thermal stability of goat milk β-lactoglobulin. Transmission electron microscopy (TEM) of samples showed that the goat milk β-lactoglobulin microstructure had changed and it contained larger aggregates when compared with the untreated goat milk β-lactoglobulin sample. Data suggested that HIU treatments resulted in secondary and tertiary structural changes of goat milk β-lactoglobulin and improved its thermal stability.

Thermal Stability of Ultrafine Grains in Al-Fe-Mn-Si Foils Prepared by ARB and Subsequent Rolling

2008 ◽  
Vol 584-586 ◽  
pp. 905-910 ◽  
Author(s):  
Petr Homola ◽  
Margarita Slámová ◽  
P. Sláma ◽  
Miroslav Cieslar
Keyword(s):  
Thermal Stability ◽  
Structural Changes ◽  
High Strength ◽  
Electron Back Scatter Diffraction ◽  
Grain Structure ◽  
Fine Grain ◽  
Hardness Increase ◽  
Cold Rolled ◽  
The Stability ◽  
Thermal Stability Of

Accumulative Roll Bonding (ARB) is a severe plastic deformation process that allows producing ultrafine-grained materials (UFG). UFG sheets exhibit enhanced strength and very fine grain structure. Foils used as fins in heat exchangers have to be very thin but must exhibit high strength combined with relatively high formability. Thus, materials produced using ARB may fulfil the exacting requirements on foil properties for such applications. The thermal stability of Al-Fe- Mn-Si foils produced using ARB and subsequent cold rolling was studied and compared with conventionally cold rolled (CCR) counterparts. The stability was assessed by isothermal annealing in the temperature range from 200 to 450 °C. Electron back scatter diffraction in a scanning electron microscope and transmission electron microscopy examinations of foils microstructure in the deformed and annealed states allowed the monitoring of structural changes. The magnitude of mechanical properties changes due to annealing was evaluated by microhardness measurements. Significant hardness increase was observed after annealing at 200 °C only in the ARB samples and was assigned to an annealing-induced hardening. The CCR foil exhibits higher non-recrystallized fraction and smaller mean lamellae boundary spacing in the temperature interval of 200-250 °C than ARB foils. The annealing at 450 °C results in identical hardness values and fully recrystallized microstructure of all foils, regardless the method used for their manufacturing. However, the ARB samples show higher stability of the refined substructure than their cold rolled counterparts due to continuous recrystallization occurring in the ARB foils.

Preparation and Crystallization Kinetics of FeSiB Amorphous Ribbons under Non-Isothermal Regime

2014 ◽  
Vol 605 ◽  
pp. 35-38
Author(s):  
Eirini Varouti
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Chemical Composition ◽  
Crystallization Kinetics ◽  
Structural Changes ◽  
Scanning Calorimetry ◽  
Amorphous Ribbons ◽  
Isothermal Regime ◽  
Kinetics Of

The aim of the present work was the preparation and characterization of FeSiB amorphous magnetic ribbons with the following chemical composition: Fe80SixB20-x, x=5,6,8 and Fe75Si15B10. Differential Scanning Calorimetry was employed in order to study the thermal stability and structural changes during the transformations that took place. Much emphasis is placed on the analysis of the crystallization kinetics.

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