Structural Features and Thermal Stability of 25,26,27,28-Tetrahydroxycalix[4]arene Molecular Complexes with Solvents

2013 ◽  
Vol 118 (1) ◽  
pp. 338-345 ◽  
Author(s):  
Oleg V. Surov ◽  
Marina I. Voronova ◽  
Vladimir P. Barannikov ◽  
Gennady P. Shaposhnikov
Keyword(s):  
Thermal Stability ◽  
Molecular Complexes ◽  
Structural Features ◽  
Thermal Stability Of

Structural features and thermal stability of molecular complexes of 25,26,27,28-Tetrahydroxycalix[4]arene with solvents

2014 ◽  
Vol 88 (8) ◽  
pp. 1329-1335 ◽  
Author(s):  
O. V. Surov ◽  
M. I. Voronova ◽  
E. V. Plevina ◽  
V. P. Barannikov ◽  
P. R. Smirnov ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Molecular Complexes ◽  
Structural Features ◽  
Thermal Stability Of

Thermal stability of the structural features in the superhydrophobic boehmite films on austenitic stainless steels

2008 ◽  
Vol 254 (16) ◽  
pp. 5129-5133 ◽  
Author(s):  
Xiaoxue Zhang ◽  
Mari Honkanen ◽  
Mikael Järn ◽  
Jouko Peltonen ◽  
Viljami Pore ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Structural Features ◽  
Thermal Stability Of

Thermal Stability of Rapidly Solidified Alloys of Aluminium with Transition Metals

2006 ◽  
Vol 519-521 ◽  
pp. 389-394 ◽  
Author(s):  
Dalibor Vojtěch ◽  
Jan Verner ◽  
Barbora Bártová ◽  
Karel Saksl
Keyword(s):  
Thermal Stability ◽  
Transition Metals ◽  
Solid Solutions ◽  
Melt Spinning ◽  
Structural Features ◽  
High Thermal Stability ◽  
Crystalline Phases ◽  
Supersaturated Solid Solutions ◽  
Rapidly Solidified ◽  
Thermal Stability Of

Rapidly solidified (RS) Al-TM (TM = transition metal) alloys are perspective materials from scientific, as well as technological point of view. Generally, they are produced by the melt atomization or by the melt spinning. Subsequent compaction is commonly performed by the hot extrusion. Since transition metals, such as Cr, Fe, Ni, Zr, Ti, Mn and others, have low diffusion coefficients in solid aluminium (lower by several orders of magnitude than those of common alloying elements like Cu, Si, Mg, Zn etc.) the RS Al-TM alloys are characterized by a high thermal stability. In this paper, several RS Al-TM (TM = Cr, Fe, Ti, Mn, Ni) alloys prepared by the melt spinning and melt atomization are compared to commercially available 2xxx, 6xxx and 7xxx wrought alloys. The main structural features of both RS and wrought alloys are described. The RS alloys are characterized by the presence of micro and nano-scale crystalline and/or quasi-crystalline phases and supersaturated solid solutions. The elevated-temperature behaviour is compared for both groups of materials. The thermal stability of the investigated materials is determined by room temperature hardness measurements after various annealing regimes and a high thermal stability of the RS alloys is demonstrated. The microstructural changes and phase transformations occurring in the investigated materials upon heating are described. In the Al-TM alloys, very slow decomposition of the supersaturated solid solutions, precipitation and decomposition of the metastable quasi-crystalline phases occur.

scholarly journals Structural features responsible for kinetic thermal stability of a carboxypeptidase from the archaebacterium Sulfolobus solfataricus

1993 ◽  
Vol 295 (3) ◽  
pp. 827-831 ◽  
Author(s):  
A Villa ◽  
L Zecca ◽  
P Fusi ◽  
S Colombo ◽  
G Tedeschi ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Thermal Inactivation ◽  
Metal Removal ◽  
Hydrophobic Interactions ◽  
Sulfolobus Solfataricus ◽  
Structural Features ◽  
Inactivation Rate ◽  
Salt Bridges ◽  
Native Conformation ◽  
Thermal Stability Of

Investigations were performed on the structural features responsible for kinetic thermal stability of a thermostable carboxypeptidase from the thermoacidophilic archaebacterium Sulfolobus solfataricus which had been purified previously and identified as a zinc metalloprotease [Colombo, D'Auria, Fusi, Zecca, Raia and Tortora (1992) Eur. J. Biochem. 206, 349-357]. Removal of Zn2+ by dialysis led to reversible activity loss, which was promptly restored by addition of 80 microM ZnCl2 to the assay mixture. For the first-order irreversible thermal inactivation the metal-depleted enzyme showed an activation energy value of 205.6 kJ.mol-1, which is considerably lower than that of the holoenzyme (494.4 kJ.mol-1). The values of activation free energies, enthalpies and entropies also dropped with metal removal. Thermal inactivation of the apoenzyme was very quick at 80 degrees C, whereas the holoenzyme was stable at the same temperature. These findings suggest a major stabilizing role for the bivalent cation. Chaotropic salts strongly destabilized the holoenzyme, showing that hydrophobic interactions are involved in maintaining the native conformation of the enzyme. However, the inactivation rate was also increased by sodium sulphate, acetate and chloride, which are not chaotropes, indicating that one or more salt bridges concur in stabilizing the active enzyme. Furthermore, at the extremes of the pH-stability curve, NaCl did not affect the inactivation rate, confirming the stabilizing role of intramolecular ionic bonds, as a pH-dependent decrease in stability is likely to occur from breaking of salt bridges involved in maintaining the native conformation of the protein.

The Ordered Phase Formation in Ti-Al-Ga Alloys

1970 ◽  
Vol 28 ◽  
pp. 440-441
Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Titanium Alloys ◽  
Growth Kinetics ◽  
Stoichiometric Composition ◽  
Good Potential ◽  
Alpha Titanium ◽  
Cold Rolled ◽  
Kinetics Of ◽  
Thermal Stability Of

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization

Microstructure studies of tungsten silicide schottky contacts on Gaas

1987 ◽  
Vol 45 ◽  
pp. 328-329
Author(s):  
Yih-Cheng Shih ◽  
E. L. Wilkie
Keyword(s):  
Thermal Stability ◽  
Field Effect Transistors ◽  
Schottky Contact ◽  
Schottky Contacts ◽  
Excellent Thermal Stability ◽  
Barrier Heights ◽  
Gaas Substrates ◽  
Film Adhesion ◽  
Threshold Voltages ◽  
Thermal Stability Of

Tungsten silicides (WSix) have been successfully used as the gate materials in self-aligned GaAs metal-semiconductor-field- effect transistors (MESFET). Thermal stability of the WSix/GaAs Schottky contact is of major concern since the n+ implanted source/drain regions must be annealed at high temperatures (∼ 800°C). WSi0.6 was considered the best composition to achieve good device performance due to its low stress and excellent thermal stability of the WSix/GaAs interface. The film adhesion and the uniformity in barrier heights and ideality factors of the WSi0.6 films have been improved by depositing a thin layer of pure W as the first layer on GaAs prior to WSi0.6 deposition. Recently WSi0.1 has been used successfully as the gate material in 1x10 μm GaAs FET's on the GaAs substrates which were sputter-cleaned prior to deposition. These GaAs FET's exhibited uniform threshold voltages across a 51 mm wafer with good film adhesion after annealing at 800°C for 10 min.

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