The effect of protective environments on the determination of melting temperatures of decomposable materials

Sound velocity and equation of state of liquids provide important constraints on the generation, presence, and transport of silicate and metallic melts in the Earth’s interior. Unlike their solid counterparts, these properties of liquids pose great technical challenges to high-pressure measurements and are poorly constrained. Here we present the technical developments that have been made at the GSECARS beamline 13-ID-D of the Advanced Photon Source for the past several years for determination of sound velocity of liquids using the ultrasonic techniques in a 1000-ton Kawai-type multianvil apparatus. Temperature of the sound velocity measurements has been extended to ~2400 K at 4 GPa and ~2000 K at 8 GPa to enable studies of liquids with very high melting temperatures, such as the silicate liquids.

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The HLM method: a simple way to get the solid–liquid phase diagrams and enthalpies of transition of pure components and mixtures

Canadian Journal of Chemistry ◽

10.1139/v92-348 ◽

1992 ◽

Vol 70 (11) ◽

pp. 2745-2750 ◽

Cited By ~ 7

Author(s):

François Quirion ◽

Daniel Lambert ◽

Gérald Perron

Keyword(s):

Differential Scanning Calorimetry ◽

Chemical Engineering ◽

Low Cost ◽

Polymer Science ◽

Scanning Calorimetry ◽

Simple Method ◽

Melting Temperatures ◽

Solid Liquid ◽

Better Than

A simple method of thermal analysis is described which gives the same information as differential scanning calorimetry. The method is based on the Heat-Leak-Modulus, HLM, of a sample cell placed in a constant temperature reservoir. In the present study, the HLM method is used for the investigation of pure components and mixtures from −190 to 50 °C. The method allows the determination of glass-transition, crystallizations, solid–solid transition, eutectic, and melting temperatures with a reproducibility better than ±0.1 °C. The enthalpy of a transition can be determined with a reproducibility of ±5%. The simplicity, the low cost, and the precision of the HLM method fills the gap between standard cooling curves and sophisticated differential scanning calorimetry experiments. The HLM method has numerous applications in physical chemistry, polymer science, metallurgy, and chemical engineering.

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Sequence Effect on the Activity of DNAzyme with Covalently Attached Hemin and Their Potential Bioanalytical Application

Sensors ◽

10.3390/s22020500 ◽

2022 ◽

Vol 22 (2) ◽

pp. 500

Author(s):

Joanna Kosman ◽

Krzysztof Żukowski ◽

Andrea Csáki ◽

Wolfgang Fritzsche ◽

Bernard Juskowiak

Keyword(s):

Telomeric Sequence ◽

Sequence Effect ◽

Sandwich Assay ◽

Silver Deposition ◽

Melting Temperatures ◽

Dna Oligonucleotides ◽

Bioanalytical Application ◽

Thermal Stability Of ◽

Oligonucleotide Sequence

In this work we investigated the effect of a DNA oligonucleotide sequence on the activity of a DNAzyme with covalently attached hemin. For this purpose, we synthesized seven DNA-hemin conjugates. All DNA-hemin conjugates as well as DNA/hemin complexes were characterized using circular dichroism, determination of melting temperatures and pKa of hemin. We observed that hemin conjugation in most cases led to the formation of parallel G-quadruplexes in the presence of potassium and increased thermal stability of all studied systems. Although the activity of DNA-hemin conjugates depended on the sequence used, the highest activity was observed for the DNA-hemin conjugate based on a human telomeric sequence. We used this DNAzyme for development of “sandwich” assay for detection of DNA sequence. For this assay, we used electric chip which could conduct electricity after silver deposition catalyzed by DNAzyme. This method was proved to be selective towards DNA oligonucleotides with mismatches and could be used for the detection of the target. To prove the versatility of our DNAzyme probe we also performed experiments with streptavidin-coated microplates. Our research proved that DNAzyme with covalently attached hemin can be used successfully in the development of heterogeneous assays.

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Determination of the bulk melting temperature of nickel using Monte Carlo simulations: Inaccuracy of extrapolation from cluster melting temperatures

Physical Review B ◽

10.1103/physrevb.81.064112 ◽

2010 ◽

Vol 81 (6) ◽

Cited By ~ 17

Author(s):

J. H. Los ◽

R. J. M. Pellenq

Keyword(s):

Monte Carlo ◽

Monte Carlo Simulations ◽

Melting Temperature ◽

Melting Temperatures

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Determination of melting temperatures in hydrocarbon mixtures by differential scanning calorimetry

The Journal of Chemical Thermodynamics ◽

10.1016/j.jct.2016.12.030 ◽

2017 ◽

Vol 108 ◽

pp. 59-70 ◽

Cited By ~ 8

Author(s):

Jordan H. Oakley ◽

Thomas J. Hughes ◽

Brendan F. Graham ◽

Kenneth N. Marsh ◽

Eric F. May

Keyword(s):

Differential Scanning Calorimetry ◽

Scanning Calorimetry ◽

Hydrocarbon Mixtures ◽

Melting Temperatures

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Thermodynamics of Shrinkage of Fibrous (Racked) Rubber

Rubber Chemistry and Technology ◽

10.5254/1.3542299 ◽

1958 ◽

Vol 31 (3) ◽

pp. 485-498

Author(s):

J. F. M. Oth ◽

P. J. Flory

Keyword(s):

Tensile Force ◽

The Other ◽

Degree Of Crystallinity ◽

Melting Point Depression ◽

Heat Of Fusion ◽

Γ Radiation ◽

Melting Temperatures ◽

The Degree Of Crystallinity ◽

Heat Of Transformation

Abstract Highly oriented natural rubber samples of Roberts and Mandelkern, prepared by racking and subsequently crosslinked using γ-radiation, undergo a spontaneous shrinkage upon melting which closely resembles the shrinkage of collagen. If the transformation is arrested by application of a tensile force, a state of equilibrium may be established between two distinct zones, or phases, one being totally amorphous (shrunken) and the other unchanged (i.e., racked). Determination of the stress τeq required for phase equilibrium at various temperatures is described. Extrapolation to τeq=0 gives equilibrium melting temperatures Tmi, which are about 8° below the temperatures Tsi for spontaneous shrinkage. The heat of transformation of racked to amorphous rubber calculated from the dependence of τeq on T is 4.5 cal g−1. Since the degree of crystallinity is only 0.24, the heat of fusion calculated for 1 g of crystalline rubber is ca. 19 cal, which agrees satisfactorily with the value 15.3 cal, deduced by Roberts and Mandelkern through use of the melting point depression method. The shrinkage of racked rubber displays all of the important features associated with the similar contraction of fibrous proteins.

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Pulsed n.m.r. studies of the crystallization kinetics of polyethylene from the melt and solution

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1979.0092 ◽

1979 ◽

Vol 367 (1730) ◽

pp. 343-351 ◽

Cited By ~ 10

Keyword(s):

Induction Period ◽

Crystallization Kinetics ◽

Volume Change ◽

Crystallization Time ◽

Rapid Crystallization ◽

Amorphous Fraction ◽

Melting Temperatures ◽

Solution Crystallization ◽

Kinetics Of

Pulsed n.m.r. techniques have been used to determine the crystallization rates of polyethylene samples, both commercial polydispersed and monodispersed, in bulk and in approximately 5 % (by mass) solution in tetrachloroethylene. Where comparable, the results agree well with those obtained by Mandelkern (1956)using volume change measurements, but extend his temperature range towards the more rapid crystallization rates. The crystallization-time curves show the existence of an induction period, and a residual amorphous fraction which is lower in solution crystallization. The results agree well with the relation between bulk crystallization rates and degree of supercooling proposed by Mandelkern et al. (1954) provided appropriate melting temperatures,T m , are used. The technique has several advantages for the determination of polymer crystallization rates.

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Development of a Thermofluor assay for stability determination of membrane proteins using the Na+/H+antiporter NhaA and cytochromecoxidase

Acta Crystallographica Section D Biological Crystallography ◽

10.1107/s1399004715004058 ◽

2015 ◽

Vol 71 (5) ◽

pp. 1112-1122 ◽

Cited By ~ 11

Author(s):

Martin Kohlstaedt ◽

Iris von der Hocht ◽

Florian Hilbers ◽

Yvonne Thielmann ◽

Hartmut Michel

Keyword(s):

Membrane Proteins ◽

Membrane Protein ◽

Temperature Dependent ◽

Easy Method ◽

Membrane Protein Complex ◽

Melting Temperatures ◽

Preliminary Information ◽

Ion Proton ◽

Ph Range

Crystallization of membrane proteins is very laborious and time-consuming, yielding well diffracting crystals in only a minority of projects. Therefore, a rapid and easy method is required to optimize the conditions for initial crystallization trials. The Thermofluor assay has been developed as such a tool. However, its applicability to membrane proteins is still limited because either large hydrophilic extramembranous regions or cysteine residues are required for the available dyes to bind and therefore act as reporters in this assay. No probe has been characterized to discriminate between the hydrophobic surfaces of detergent micelles, folded and detergent-covered membrane proteins and denatured membrane proteins. Of the four dyes tested, the two dyes 1-anilinonaphthalene-8-sulfonic acid (ANS) and SYPRO Orange were systematically screened for compatibility with five detergents commonly used in the crystallization of membrane proteins. ANS showed the weakest interactions with all of the detergents screened. It was possible to determine the melting temperature of the sodium ion/proton antiporter NhaA, a small membrane protein without large hydrophilic domains, over a broad pH range using ANS. Furthermore, cytochromecoxidase (CcO) was used to apply the method to a four-subunit membrane protein complex. It was possible to obtain preliminary information on the temperature-dependent denaturation of this complex using the dye ANS. Application of the dye 7-diethylamino-3-(4′-maleimidylphenyl)-4-methylcoumarin (CPM) to CcO in the Thermofluor assay enabled the determination of the melting temperatures of distinct subunits of the complex.

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