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The Debye model has been developed to study the pressure dependence of the extended X-ray absorption fine structure Debye–Waller factor, the Debye frequency and temperature of hexagonal close-packed (hP2) metals. The effects of the non-ideal axial ratio c/a of hP2 structure on these thermodynamic quantities at high pressures have also been considered. Additionally, based on the combination of the Debye model and the Lindemann melting law, we derive the analytic expression of melting temperature of hP2 metals as a function of pressure. Numerical calculations have been implemented for Mg and Zn metals up to 20 and 50 GPa, respectively. We have shown that Debye frequency and temperature, as well as melting temperature of these two metals increase robustly with pressure and non-ideal axial ratio plays important role in these thermodynamic quantities. The remarkable consistency observed between our calculations and various experimental results validates the reliability of the currently presented melting curve. Meanwhile, at high pressure non-ideal axial ratio gives a small contribution to pressure-dependent Debye–Waller factor of Mg (up to 20 GPa) and Zn (beyond 20 GPa), and can be safely neglected in the suggested pressure range. [ABSTRACT FROM AUTHOR]

Freezing of water has a direct impact on the durability of cementitious materials, which include porous binding phases, like calcium-silicate-hydrate (CSH). Molecular dynamics (MD) simulations can capture behaviors of the water freezing in the pores and may give rise to insightful observations. In this work, the monoatomic water (mW) model and all-atom CSH model are combined to study low-temperature behavior of water molecules restricted within CSH layers. The developed model features good accuracy and accelerated computational rate, and is employed to study how ultra-confined water in CSH phases (≤6 nm) freezes. The threshold width of CSH gap that allows the stable existence of ice is 1.5 ± 0.1 nm. A non-icing layer with an average thickness of ∼0.65 nm exists ambient to CSH surface. The main factor affecting the melting point of confined water is the size of the confined space rather than the water filling fraction. The Gibbs-Thomson model is utilized to describe the relationship between the melting temperature and the width of the confined CSH layers. The utilization of this modeling technique presents a novel approach to replicate the freezing process of nanostructures in cementitious composites subjected to low-temperature erosion. [ABSTRACT FROM AUTHOR]

A numerical modeling methodology based on the finite element method is utilized in this investigation to predict the impact of the PCM characteristics on the system cooling performance and the solar module output power. The thermal analysis considers the transient nature and the nonlinearity of the problem. The boundary conditions include the cyclic variation with time of solar irradiance and ambient temperature in a hot climatic region, with peak temperatures close to 50 °C. Under these circumstances and owing to the various influencing parameters, choosing an appropriate PCM is a challenging task. By allowing the PCM characteristics to vary continuously over the applicable domains and not just by giving specified discrete values, a systematic approach is adopted in this work. This technique is applied to explore the relationships between system input parameters, as defined by the PCM properties, and output variables, as described by cell temperature and module efficiency. Due to the harsh boundary conditions, the obtained results demonstrated that PCM with high thermal conductivity is required to achieve efficient thermal regulation. The enhanced material characteristics can only be provided by composite PCMs with graphite or metal additives. The resulting optimized design variables of the suitable PCM, melting temperature, thermal conductivity, and thickness, can reduce the cell temperature to 57 °C (20% reduction). The corresponding efficiency and power output are raised by around 8%. The power output was found to increase from 125 W (reference case) to 135 W for the optimized case. The results suggest that using a passive cooling system based on PCM is a viable method for enhancing the power output of a solar PV module. The created coupled model predicts the thermal behavior of the PV module and significantly facilitates the PCM selection procedure to ensure its applicability. [ABSTRACT FROM AUTHOR]

Stable flow and discharge of the slag in an entrained flow gasifier are the key factors to ensure the long-term stable operation of gasifier. In this work, the melting and flow behavior of coal ash with different Fe2O3/SiO2 ratios was studied in a reduced atmosphere. The results show that the viscosity of slag decreases significantly with the increase of Fe2O3/SiO2. And the critical viscosity-temperature (TCV) decreases from 1309°C to 1226°C. It is found that more than 90% of iron ions exist in the form of Fe2+ in liquid slag by chemical titration. There are more simple ion clusters with low bridge oxygen number (BO) with the increase of Fe2+ and lead to depolymerization of slag. Furthermore, the ash with high SiO2 content can be transformed into slag with high viscosity at a low melting rate by the analysis of the slag area curve and X-ray diffraction pattern, which is considered to be controlled by the "softening-melting" mechanism. The ash with high Fe2O3/SiO2 can be transformed rapidly into a low viscosity liquid at a short melting interval, which follows the "melting-dissolution" mechanism. And it is helpful to promote the formation of low-temperature eutectics with the increase in Fe2O3/SiO2 by thermodynamic calculation. Research on the melting mechanism of slag will provide theoretical support for the regulation of slag flow characteristics. [ABSTRACT FROM AUTHOR]

Red mud produced from the Bayer process was used for the high temperature metallurgical processing of ilmenite. The major components of the red mud were Fe2O3, Al2O3, Na2O, and TiO2, which play important roles in the flux material. The process temperature of ilmenite slag was lowered from 1794 K (1521°C) to 1687 K (1414°C), as a preliminary study by a high-temperature microscope. Thermochemical calculations using FactSageTM 7.0 confirmed the effect of red mud on the lowered melting temperature of ilmenite slag. The discrepancy between the observed results of the microscope and the calculated phase diagram was due to the slag viscosity, which was significantly affected by Al2O3 in red mud. The reduction of ilmenite at lower temperatures by the addition of red mud was investigated at 1723 K (1450°C). Ilmenite, pseudobrookite, and associated clay minerals were the major phases in the reduced ilmenites which was confirmed by X-ray diffraction (×RD) analysis. Microscopic images obtained by scanning electron microscopy (SEM) showed variations in the pseudobrookite phases according to the amount of fluxed red mud. The benefits of red mud utilization are discussed with regard to the lower energy consumption and recovery of resources. [ABSTRACT FROM AUTHOR]

The melting of micro/nanoparticles considering the Soret effect in an alloy melt is studied in terms of the asymptotic method. The results reveal that the positive Soret coefficient weakens the dynamic disequilibrium near the interface, and then enhances the melting temperature of the particle and decreases the melting speed of the particle. The negative Soret coefficient strengthens the dynamic disequilibrium near the interface, and then reduces the melting temperature of the particle and increases the melting speed of the particle. The positive Soret coefficient weakens the accumulation of the solute flux near the interface and enhances the solute concentration. The negative Soret coefficient strengthens the accumulation of the solute flux near the interface and reduces the solute concentration. The size dependence of the melting temperature considering the Soret coefficient is quantitatively consistent with the experimental data, especially for the micro/nanoparticles with a radius smaller than 5 nm. [ABSTRACT FROM AUTHOR]

An empirical relationship has been found to evaluate the bulk modulus (B) and shear modulus (G) with the help of two experimental physical quantities (the melting temperature and the crystal ionicity), which are drawn from various pieces of literature. The PVV theory of crystal ionicity and temperature dependence of elasticity are taken into account for the study. The evaluated bulk modulus and shear modulus values are found to be in excellent conformity with experimental and reported values of other researchers. The current research supports the modelling of emerging semiconductor materials and even understanding of their mechanical properties for photovoltaic, spintronics, LiB systems, FLB phenomenon, and superhard material applications. [ABSTRACT FROM AUTHOR]

Understanding the melt layer of composite solid propellants is crucial to theoretically model the combustion mechanism. Numerous studies on the melt layer flow have determined that the melting temperatures of the binder govern the burning rate dependence on pressure. Previous investigations discovered that using curatives and using different binders alter the binder melting temperature. The authors have developed a process to tailor the melting temperature through a functionalization process on the hydroxyl-terminated polybutadiene (HTPB) polymer. This study presents the analysis on the impacts of the melt layer dynamics of an ammonium perchlorate (AP)/HTPB-based propellant with tailorable melting temperatures. Pyrolysis measurements observed increased binder melt layer flow, resulting in lower pyrolysis rates. Propellants made with similar melting temperatures to the traditional R45M had similar burning rates but introduced more scatter due to the hardness of the propellant. Additional propellant samples containing 17 wt% aluminum (Al) and 70 wt% AP were made with a range of melting temperatures to study the impact of melting temperature on the melt layer. A rheological study on the cured propellant mixtures with tailored melting properties identified the melting temperatures for the level of HTPB functionalization. Those mixtures were burned, and the burning rates varied based on the melting temperature. The results suggested that a lower melting temperature produces a plateau propellant. [ABSTRACT FROM AUTHOR]

The TTMF2.1-F model is a non-empirical intermolecular water potential parametrised from ab-initio calculations of the water dimer with a complete basis set limit including dispersion correction from second-order Moller-Plesset perturbation theory. In this work, using two-phase ice-water NVT molecular-dynamics (MD) simulations, we found the ice melting temperature using the TTM2.1-F potential is close to 273 K when the nuclear quantum effects (NQEs) were included using path-integral centroid MD. Detailed analysis of the radial distribution functions, angle distribution functions, and associated joint probability for both liquid water and the two-phase cases showed that the melting-point-temperature drop when using path-integral simulation is due to the weakening of hydrogen bonds vis-à-vis classically-propagated MD. [ABSTRACT FROM AUTHOR]

New polyoxamides, poly(m-xylylene oxamide) (PMXD2) and its copolymer with 2-methyl-1,5- pentanediamine (P(MXD2/M52)) with relative viscosity up to 4.6 were synthesized via spray/solid state polymerization. The obtained polyoxamides were characterized by FTIR, NMR, WAXD, DSC and TGA. The Tm of the copolymers decreased with increasing percentage of poly(2-methyl-1,5- pentaneoxamide) (PM52) in the copolymer from 346°C for 100% poly(meta-xylyleneoxamide) (PMXD2) to 277°C for copolymers of PMXD/PM52 (60/40). TGA analysis revealed that the thermal stability of the copolymers compared well with commercial PA6 and XRD studies suggested the copolymers possessed high crystallinity. DMA profile of the PMXD/PM52 (70/30) copolymer showed better mechanical performance with a storage modulus of about 7.2 GPa as compared to 1.8 GPa of PA6 at 25°C. [ABSTRACT FROM AUTHOR]

A nonmetallic organophosphate salt, ammonium 2,2′- methylene-bis-(4,6-di-t-butylphenylene) phosphates (An), was synthesized via a simple method, and its application in iPP as a nucleating agent was investigated. Differential scanning calorimetry (DSC) result showed the melting temperature of An was 262°C, and SEM (scanning electron microscopy) observations indicated that its crystallization morphology was lamellar shape with a quite smooth surface. The crystallization behavior of nucleated isotactic poly(propylene) (iPP) containing An demonstrated that An can effectively raise the crystallization peak temperature and reduce the spherulite size, resulting in obviously improved strength and transparency. The tensile and flexural strength of iPP nucleated with An was increased by 11% and 32%, respectively. The haze value of iPP/An was decreased from 36.7% to 15.5%. These results revealed that this organophosphate ammonium salt can be used as an effective nucleating agent of iPP and provides a new organophosphate salt type nucleating agent for polymers. [ABSTRACT FROM AUTHOR]

Crystallisation of liquid solutions is of uttermost importance in a wide variety of processes in materials, atmospheric and food science. Depending on the type and concentration of solutes the freezing point shifts, thus allowing control on the thermodynamics of complex fluids. Here we investigate the basic principles of solute-induced freezing point depression by computing the melting temperature of a Lennard-Jones fluid with low concentrations of solutes, by means of equilibrium molecular dynamics simulations. The effect of solvophilic and weakly solvophobic solutes at low concentrations is analysed, scanning systematically the size and the concentration. We identify the range of parameters that produce deviations from the linear dependence of the freezing point on the molal concentration of solutes, expected for ideal solutions. Our simulations allow us also to link the shifts in coexistence temperature to the microscopic structure of the solutions. [ABSTRACT FROM PUBLISHER]

The melting point of liquid lithium near zero pressure is studied with large-scale orbital-free first-principles molecular dynamics (OF-FPMD) in the isobaric-isothermal ensemble. We adopt the Wang-Govind-Carter (WGC) functional as our kinetic energy density functional (KEDF) and construct a bulk-derived local pseudopotential (BLPS) for Li. Our simulations employ both the ‘heat-until-melts’ method and the coexistence method. We predict 465 K as an upper bound of the melting point of Li from the ‘heat-until-melts’ method, while we predict 434 K as the melting point of Li from the coexistence method. These values compare well with an experimental melting point of 453 K at zero pressure. Furthermore, we calculate a few important properties of liquid Li including the diffusion coefficients, pair distribution functions, static structure factors, and compressibilities of Li at 470 K and 725 K in the canonical ensemble. Our theoretically-obtained results show good agreement with known experimental results, suggesting that OF-FPMD using a non-local KEDF and a BLPS is capable of accurately describing liquid metals. [ABSTRACT FROM AUTHOR]

X-ray diffraction (XRD) of cellulose acetate (CA; degree of substitution >2.4) fibers stretched in solvent suggests the existence of a third polymorph of cellulose triacetate (CTA). Comparison of these results with patterns from model structures indicates that it has an antiparallel two-chain unit cell with space group P21221. XRD, differential scanning calorimetry (DSC), and modeling results have shown that the polymorph forms small crystallites, which are less stable than CTA I and CTA II. DSC studies of CA with different degrees of substitution suggest that CTA III forms when the number of contiguous triacetylated monomers is less than the minimum sequence length required for formation of CTA II. [ABSTRACT FROM AUTHOR]

Using the diacetate of 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphorin-10-oxide, p-acetoxy-benzoic acid, terephthalic acid and the condensation product of terephthalic acid and 1,8-octanediamine as monomers, a new kind of flame-retardant thermotropic liquid crystal copolyester containing phosphorus, nitrogen and 1,8-octanediamine softsegment (PN-TLCP) was synthesized by melt condensation polymerization. The structure and properties of PN-TLCP, such as molecular structure, texture of liquid crystal and thermal properties were investigated by fourier transform infrared spectra, X-ray diffraction, hot-stage polarizing optical microscope, differential scanning caborimetry and thermal gravimetric analysis. The results showed that the texture of PN-TLCP was the type of nematic liquid crystalline within the bounds of 180∼330°C, and its melting point was 148°C. It was proved that there were P-O and P=O stretching vibration absorption bands and C-N and C=N mixed absorption bands in Fourier transform infrared spectra of PN-TLCP. Also, the thermal stability and the char yield of PN-TLCP are favorable. [ABSTRACT FROM AUTHOR]

Measuring glass transition temperature is necessary for predicting the state and the behavior during the processing, distribution, and storage of many amorphous sugar-rich products. Therefore, the purpose of this study was to establish an improved calorimetric methodology to assess T g in amorphous sugars. This method was created through melting crystal with differential scanning calorimetry (DSC) using the same principle proposed by Jiang, Liu, Bhandari, and Zhou (2008. Impact of caramelization on the glass transition temperature of several caramelized sugars. Part I: chemical analyses. Journal of Agricultural and Food Chemistry, 56, 5138–5147). Thermogravimetric analysis with simultaneous DSC was required to characterize the melting and thermal degradation temperatures of sugars. Thermograms showing the complete process of heating–cooling–reheating are proposed to determine the precise glass transition temperature during cooling (T gC) or reheating (Tg H), and to verify if the processed amorphous samples were created with or without thermal degradation. The melting temperature has little effect on the T g value whereas the sugar was melted without thermal degradation. Thus, using this methodology the precise T g value of amorphous sugars can be determined. [ABSTRACT FROM AUTHOR]

The beta irradiation of polybutene-1 (PB-1) and its random copolymers with ethylene results in sample degradation without chain cross-linking. The crystal structures of both homopolymer and ethylene copolymers were phase I (I), except that for samples of short time irradiation, after melting, where phase II (II) was also present. The sample crystallinity decreased from 64% to a low of 45% in the irradiated samples for the condition used. The crystal size/perfection of the transformed I was slightly lower than that of parent II. The beta irradiation increased the transformation rate of II → I but to a lower extent than did the amount of ethylene in the copolymers. IR analysis confirmed that electron irradiation resulted in chain scission and a decrease of ‒CH2‒ and ‒CH3 groups. The mechanical properties decreased with increasing ethylene content and irradiation dose. [ABSTRACT FROM PUBLISHER]

Tri (p-N-phenyl acrylamido) methanol (PAM) monomer was firstly prepared followed by a trial to polymerize it in tetrahydrofuran (THF) by γ- ray from a 60Co to form a new polymer (PPAM). The characterization of the prepared monomer and its polymer was carried out by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (1H-NMR), ultraviolet-visible spectrophotometer (UV-Vis), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The melting temperature (Tm) and thermal stability of the prepared monomer and its polymer were determined using DSC and TGA investigation, the molecular weight of the radiation prepared polymer at 100 kGy was determined by Gel permeation chromatography (GPC) analysis. The change in surface morphology of both the monomer and its polymer substrate was observed by scanning electron microscopy (SEM). [ABSTRACT FROM AUTHOR]

Determination of melting temperature by spectroradiometric technique, aided by visual observation of onset of melting by track formation method employing an infrared CO2 laser, was carried out. Melting temperatures of SrTiO3 and MgO single crystals and silicon wafer samples obtained by this novel technique are reported. Melting temperatures obtained by this method are within 2% of the reported standard values. These values are used to validate temperature measurements carried out in laser heated diamond anvil cell experiments. [ABSTRACT FROM PUBLISHER]

Potato starch has great processability and formamide could provide excellent plasticization. Consequently, potato starch was modified into formamide pseudo-thermoplastic potato starch (FTPP) films in this study. For the evaluation of the optimum preparation on FTPP, we focus on analysis of the plasticizers effect and properties. The results show that the strength and elongation of FTPP-20 film were respectively 29.7 MPa and 6.7%, the melting temperature (129.8°C), melting heat (270.3 J/g), degradation temperature (295.0°C), and the characterization were better than plasticized potato starch with glycerol. It is advantageous on the production and application for the biodegradable materials. [ABSTRACT FROM AUTHOR]

The melting temperature and behaviour of gold nanowire in a single-walled carbon nanotube (SWNT) were investigated in detail using molecular dynamics simulations. The results showed that the melting temperature of the enclosed Au nanowire is lower than its bulk counterpart and higher than that observed for free-standing ones. Different from the melting behaviour of freestanding Au nanowires, the melting of Au nanowires enclosed in SWNTs with tube diameters (D) in the range 1.08 nm < D < 2.09 nm investigated here was found to initiate from the centre layers. The predicted melting temperature and behaviour of gold nanowires in SWNTs were clearly shown to be dependent on the interaction between C and Au atoms. The interaction is helpful to further stabilize the structure of enclosed Au nanowires, in particular, the outermost layer. [ABSTRACT FROM AUTHOR]

This review focuses on the thermal properties of bound water restrained by various kinds of polysaccharides and several synthetic polymers. The characteristic features of freezing bound water which is closely related with biocompatibility of polymers are summarized based on results obtained by differential scanning calorimetry. Glass transition, cold crystallization and melting of water-polysaccharide systems were observed. Three kinds of water, non-freezing, freezing bound and free water, were quantified from the enthalpy of melting of water in the system. Freezing bound water restrained by polysaccharides is in a metastable state. The equilibrium melting temperature of freezing bound water is lower than 0°C and the temperature decreases with decreasing water content. Nucleation and growth rate of freezing bound water were calculated from isothermal crystallization and the values were compared with those of free water. [ABSTRACT FROM AUTHOR]

Phase equilibria and thermodynamic properties in the Fe-Cr system have been reviewed comprehensively based on experimental information and available computer simulations in different scales. The evaluated phase equilibria show significant differences from the currently accepted thermodynamic description by CALPHAD (calculation of phase diagram) approach. The thermodynamic properties of the Fe-Cr system, such as heat capacity, enthalpy, and activity, have been evaluated in reported experiments. The experiments on phase separation in the Fe-Cr system have also been critically reviewed with a focus on spinodal decomposition. The reported data are concentrated in the temperature range from 673 to 823 K. In addition, there is a transition region between spinodal decomposition and nucleation regimes within the composition limit from 24 to 36.3 at.% Cr and the temperature range between 700 and 830 K. In view of the importance of magnetism in the Fe-Cr system, some inadequacies of the currently used thermodynamic description are pointed out in addition to some problems with the current magnetic model. Remaining issues on the thermodynamics of the Fe-Cr system have been elaborated for future refinement of the thermodynamic description of the Fe-Cr system. According to the present review, the melting temperature of Cr is recommended to be about 2136 K, which is 44 K lower than the value adopted in the research community on thermodynamics, such as the Scientific Group Thermodata Europe. [ABSTRACT FROM AUTHOR]

Uniform electric current at infinity is applied to a thin infinite conductor with an elliptical hole disturbing the electric current, which gives rise to Joule heat, temperature increase and heat flux. Joule heat produces uniform and uneven temperature fields which in turn initiate thermal stress. These electrical current, Joule heat, temperature, heat flux and thermal stress analyses are carried out and their closed form solutions are obtained. The heat conduction problem is solved as a temperature boundary value problem. Figures of distribution of Joule heat, temperature, heat flux and stress are shown. A dislocation and a rotation terms for thermal stress analysis appear, which makes problem complex. Solutions of Joule heat, temperature, heat flux and thermal stress are nonlinear for the direction of electric current. For an infinite plate with a circular hole, stress components do not occur on the whole plate. As a special case, a crack problem is analyzed and intensities at the crack tip of each problem are investigated. Relations between melting temperature and electric current density, and between fracture toughness value and electric current density are investigated for some crack lengths for steel. [ABSTRACT FROM AUTHOR]

Ultrasonic velocity and density of poly(ethylene glycol) (PEG) (mol. wt. 2000 and 8000) solutions in water and benzene have been studied as a function of temperature from which respective isentropic compressibility has also been calculated. The velocity (as well as isentropic compressibility) undergoes a sudden change near melting temperature, Tm, of the solute polymer. Normally, we expect only one peak in viscoelastic properties at the Tm of PEG. However, we see two peaks (Tm1 and Tm2) in the case of the aqueous solution of PEG while there is only one peak for the case of benzene solution. This has been interpreted on the basis that one of the peaks (Tm1) is for unsolvated PEG and the other peak (Tm2) is that of PEG with water solvation shell. Such solvation shell is not formed with the aprotic solvent (benzene). [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations have been carried out for glycerol-water-sodium chloride ternary solution due to its important role in cryopreservation engineering. The radial distribution functions for atom pairs potentially related to C-H ··· O and O-H ··· O hydrogen bonds were calculated. The radial distribution functions for the H (connected to C)-O atom pair do not exhibit peaks between 2 and 3 Å, whereas the radial distribution functions for the C-O atom pair exhibit distinct peaks between 3 and 4 Å. The reason for this is because most C-H ··· O geometries are bent and deviate from linearity. The ratios of acceptor to donor numbers for water and glycerol molecules decrease as the solute concentration increases. A characteristic concentration has been found that divides solutions with different mechanisms. Below the characteristic concentration, the melting temperature is linearly related to the ratio of acceptor to donor number for water molecules, whereas above the characteristic concentration, the melting temperature is linearly related to the ratio of acceptor to donor number for glycerol molecules. Further studies indicate that the relations are independent of hydrogen bonding criteria and temperature. [ABSTRACT FROM AUTHOR]

Lindemann's melting criterion remains useful. However, one prediction it makes for liquid metals (our focus here) is that the long-wavelength limit of the structure factor S(q) at freezing, STm(0), where Tm is the melting temperature, is a universal constant. For 34 metals we have calculated STm(0) from input data, which is essentially the measured Tm and the surface thickness L, defined near freezing as the product of isothermal compressibility and surface tension. To complete the characterization of STm(0) we fit to one metal, chosen as Rb, for which STm(0) is well established experimentally. For a wide variety of metals considered, STm(0) is then found to vary by a factor of 10. [ABSTRACT FROM AUTHOR]

The thermal expansivity and mean-square thermal vibrational amplitudes were determined as a function of temperature for thorium from first principles total energy calculations using the full potential linearized augmented plane wave (FP-LAPW) method. The coefficient of thermal expansion determined from variation of theoretical potential energy with interatomic separation is ∼1.427 × 10-5 K-1 as compared to an experimental value of 1.23 × 10-5 K-1. The mean-square thermal vibrational amplitudes determined as a function of temperature from the theoretically calculated volume-dependent Debye temperature agree well with experimental data derived form neutron diffraction measurements. The melting temperature of thorium, determined theoretically from the mean-square thermal vibrations and the Lindemann rule for melting, is 2234 K, as compared to the reported experimental value of 2021 K. [ABSTRACT FROM AUTHOR]

Concentration, gel strength (Bloom), and pH effects on both melting and gelling temperatures of gelatin were studied using small amplitude oscillatory rheology. Temperature sweeps were applied to gelatin gel samples for heating and cooling at fixed frequencies. Results showed that melting temperatures were higher than gelling temperatures, and both increased with increasing concentration at pH from 3 to 6 for all gel strength. For constant gelatin concentration and pH, as gel strength increased, melting temperatures decreased, whereas gelling temperatures increased. A mathematical model was obtained which correlates melting and gelling temperatures, respectively, with pH and concentration at fixed Bloom degrees. All gelatin gels showed storage modulus higher (2 to 10 kPa) than loss modulus (50 to 500 Pa). [ABSTRACT FROM AUTHOR]

High-resolution melting of DNA is a simple solution for genotyping, mutation scanning and sequence matching. The melting profile of a PCR product depends on its GC content, length, sequence and heterozygosity and is best monitored with saturating dyes that fluoresce in the presence of double-stranded DNA. Genotyping of most variants is possible by the melting temperature of the PCR products, while all variants can be genotyped with unlabeled probes. Mutation scanning and sequence matching depend on sequence differences that result in heteroduplexes that change the shape of the melting curve. High-resolution DNA melting has several advantages over other genotyping and scanning methods, including an inexpensive closed tube format that is homogenous, accurate and rapid. Owing to its simplicity and speed, the method is a good fit for personalized medicine as a rapid, inexpensive method to predict therapeutic response. [ABSTRACT FROM AUTHOR]

The melting temperature, T m , of copper has been determined from ambient pressure to 16 GPa using multi-anvil techniques. The melting curve obtained ( T m =1355(5)+44.5(31) P -0.61(21) P 2 , with T m in Kelvin and P in GPa) is in good agreement with both the previous experimental studies and with recent ab initio calculations. [ABSTRACT FROM AUTHOR]

We prepared 15-mer homopyrimidine oligonucleotides containing three or four 2′,5′-linked DNA units, and their ability as a triplex-forming oligonucleotide (TFO) was analyzed in detail. UV melting experiments showed that replacement of a 3′,5′-linkage by a 2′,5′-linkage at every third or fourth residue in TFO significantly promoted stable triplex formation under physiological conditions. [ABSTRACT FROM AUTHOR]

A back-propagation neural network method has been developed to predict the stability of DNA/DNA duplexes. Calculated T m with the present parameters fits the experimental values within reasonable errors (AD = 1.86 K, SEP = 1.99151, R2 = 0.9894 for NN1; AD = 1.59667 K, SEP = 2.03824, R2 = 0.99371 for NN2), and it has the advantage that the determinations of thermodynamic parameters are not needed. [ABSTRACT FROM AUTHOR]

Modulated Differential Scanning Calorimetry (MDSC) was used to investigate thermal transitions of pomegranate extracts as a function of concentration. The transitions were the glass transition temperatures (Tg) and maximum freeze-concentration condition (Tg), melting points (T'f), the onset temperatures of ice melting (T'm), and latent heat of fusion (HL). In addition, the specific heat (Cp) below and above freezing was also determined. The soluble solid contents for the pomegranate extracts ranged from 20 to 53°Brix. The Tg and T'g values ranged from -43.3 to -49.3 and from -44.9 to -52.0°C, respectively. On the other hand, Tf and T'm ranged from -2.6 to -16.7 and from -39.6 to -45.3°C, respectively. The latent heat of fusion was between 61.6 and 204.7 kJ/kg. Below freezing, a linear relationship was established between specific heat and temperature, while above freezing range the change of specific heat was relatively low. [ABSTRACT FROM AUTHOR]

The density-temperature diagram for SPC/E water at one bar pressure is studied with correct treatment of long-range potentials. The density maximum was obtained at temperature 240 K. The melting temperature for ice I h is estimated to be 225±5 K from the simulations of ice/water coexistence. A local order parameter for ice/water interface is discussed. [ABSTRACT FROM AUTHOR]

Debye temperatures T D of some perovskite compounds are determined by X-ray diffraction. Correlation between T D determined at T=180 °C, mean square displacements of atoms, quasi-elastic coupling, and melting temperature of the perovskite compounds is analysed. [ABSTRACT FROM AUTHOR]

The critical temperature of heavy n -alkanes is predicted from the behaviour corresponding to their melting temperature and from several empirical correlations. The prediction methods for the critical temperature of n -alkanes are reviewed, including the new experimental data currently available. The results obtained for $ T_c^\infty $ , the limiting value of the critical temperature at n → ∞, are compared. The calculated and experimental values of T c coincide in the range n = 5-36 within the actual uncertainties. [ABSTRACT FROM AUTHOR]

Miscibility and phase behavior studies of thermoplastic poly-ether-based polyurethane (TPEU) and poly(vinylidene fluoride) (PVF2) blends were investigated by means of Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetry (TGA), and mechanical behavior. TPEU based on 1,6-diisocyanohexane (HDI), 1,4-bu-tanediol (BD), and 1000 molecular weight poly(tetramethylene oxide) (PTMO) was synthesized. It was shown by FTIR that the addition of PVF2 to TPEU disrupted the intermolecular interactions between soft and hard segments in TPEU, and the interactions between an urethane carbonyl and protons of PVF2 was stronger than that between urethane carbonyl and urethane NH. It was found that PVF2 was immiscible with soft segment (PTMO) and miscible with hard segment and the degree of phase purity of the soft domain increased with increasing PVF2 content. The presence of a specific intermolecular interaction between the hard segment and PVF2 was suggested by an observed systematic depression in the melting point of the PVF2 component. It was also found that the thermal stability, tensile strength, and Young's modulus increased proportionally to PVF2. [ABSTRACT FROM AUTHOR]