Search

In this work, two TNBA-based low eutectic mixtures, TNBA/TNAZ (TZ) and TNBA/DNTF (TD), as well as eight TNBA-based melt-cast explosives, TNBA/TNAZ/RDX (TZR), TNBA/TNAZ/HMX (TZH), TNBA/TNAZ/TKX-50 (TZT), TNBA/TNAZ/CL-20 (TZC), TNBA/DNTF/RDX (TDR), TNBA/DNTF/HMX (TDH), TNBA/DNTF/TKX-50 (TDT) and TNBA/DNTF/CL-20 (TDC), were developed as structural models. A molecular dynamics approach was used to model the cohesive energy density, binding energy, and mechanical properties of these explosives. Moreover the thermal decomposition properties and mechanical sensitivity were characterized via DSC and mechanical sensitivity tests. Finally, the EXPLO-5 software predicted the detonation properties and detonation products of the aforementioned 10 mixed explosive systems. The results showed that the four mixed explosives of TDT, TDH, TZC, and TDR had excellent performance in cohesive energy density, binding energy, and material rigidity, respectively. The temperature difference was comparatively significant between the melting temperature and decomposition temperature of the eight types of mixed explosives, up to 170.60 K, with TDH and TZH having the highest thermal decomposition temperature at approximately 520 K. The six kinds of mixed explosives of TZR, TZH, TZT, TDR, TDH, and TDT had moderate mechanical sensitivities. . The five types of mixed explosives, TZT, TZC, TDH, TDT, and TDC, had the greatest detonation velocity. [ABSTRACT FROM AUTHOR]

In response to the urgent need for latent heat thermal energy storage (LHTES) in the cryogenic field and the utilization of renewable energy sources, three novel eutectic phase change materials (PCMs) have been successfully developed. These materials, methyl laurate (ML)/lauric acid (LA), methyl laurate/myristic acid (MA), and methyl laurate/palmitic acid (PA), belong to the eutectic system of fatty acid methyl ester (FAME) and fatty acid. With a specific composition, these binary mixtures have desired melting temperatures, high melting enthalpy, and stable thermal performance. The phase diagrams of the eutectics were analyzed to obtain precise eutectic mass ratios. Theoretical predictions of the eutectic mass ratios and thermal properties were validated and determined through differential scanning calorimetry (DSC) and the hot-disk method. The ML-LA, ML-MA, and ML-PA mixtures had onset melting temperatures of 4.19°C, 5.45°C, and 5.69°C, respectively, with corresponding enthalpy of fusion values of 185.43, 190.47, and 194.39 J/g. The cycling stability test results showed that these mixtures had good thermal stability. The thermophysical properties and molecular structure of the mixtures were analyzed, indicating that these new mixtures of ML and fatty acids are suitable for low-temperature LHTES applications such as cold compresses and thermal-regulating textiles. This study provides insight into developing new PCMs that can meet the demand for LHTES in the cryogenic field and the utilization of renewable energy sources. [ABSTRACT FROM AUTHOR]

Allantoin eutectics with choline chloride (ACM) and zinc chloride (AZM) are reported. The solid–liquid phase diagram showed the eutectic point in allantoin-rich region (Xallantoin = 0.9) for ACM. In AZM, the eutectic formation occurred in the equimolar mixture. The H-bonded template in pure allantoin was disrupted upon addition of choline chloride or zinc chloride, which led to freezing point depression. Classical and non-classical hydrogen bonding, electrostatic and donor–acceptor interactions existed among the components. Infrared vibrational frequencies indicated the involvement of ureido NH2, and ring carbonyl of allantoin, OH group of choline chloride, and Zn2+ in interactions. Thermogravimetric analysis showed that among equimolar mixtures ACM5 was more stable than AZM5. An increase in zinc chloride content markedly altered the thermal stability in AZM. Both categories of eutectics were universally soluble in dimethyl sulfoxide. Skin wounds in rabbit models were healed more effectively by concoctions containing relatively smaller percentages of eutectics. [ABSTRACT FROM AUTHOR]

Eutectics are multicomponent systems which are an alternative to the conventional techniques for modulating the biopharmaceutical properties of a pharmaceutical. Ezetimibe (ETZ) is a hypocholesterolemic agent with limited dissolution, poor water solubility, and subsequently demonstrates low oral bioavailability. Additionally, ETZ exhibits poor mechanical properties, leading to difficulties in developing dosage forms through direct compression. The present work highlights the applicability of eutectics in the simultaneous improvement of physicochemical along with mechanical properties of ETZ. A pharmaceutical eutectic of ETZ with succinimide (SUC) was prepared by mechanochemical grinding and thoroughly characterized using thermoanalytical, X-ray diffraction, and spectroscopic methods. Intrinsic dissolution rate and pharmacokinetic analysis were also performed for ezetimibe-succinimide (ETZ-SUC) eutectic in contrast to pure ETZ. The eutectic demonstrated ∼2-fold increase in the solubility and dissolution rate. In pharmacokinetic studies, the area under the curve (AUC) for ETZ-SUC eutectic (28.03 ± 2.22 ng*h/mL) was found to be higher than ETZ (8.98 ± 0.36 ng*h/mL), indicating improved oral bioavailability for eutectics. Also, it was observed that enhanced material functionality aids in designing directly compressed tablets, where the eutectic formulation showed an improved dissolution profile over the ETZ formulation. The study demonstrates that eutectic conglomerates could be utilized to develop ideal oral solid dosage formulations. [ABSTRACT FROM AUTHOR]

In this work, DSC tests were performed on 1-methyl-3,4,5-trinitropyrazole (MTNP) and 1,3,3-trinitroazetidine (TNAZ) binary eutectic systems with different molar ratios, and we drawn the T-X and H-X phase diagrams. We get the ratio of MTNP/TNAZ eutectic system by phase diagram, and the eutectic of the two were characterized by Energy spectrum analysis(EDS), X-ray diffraction(XRD), fourier transform infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), thermodynamic analysis, thermo gravimetric mass spectrometry (TG-MS), thermal sensitivity test, mechanical sensitivity test and detonation performance calculation. The results show that the ratio of MTNP/TNAZ eutectic system is 46.3/53.7, and the melting point is 72.58°C. EDS shows that there is no impurities in the lowest eutectic mixture. XRD indicates that there is some intermolecular force between the lowest eutectics mixture, which changes the diffraction peak. IR shows that the raw MTNP and raw TNAZ do not react with each other after forming the lowest eutectic mixture. Thermodynamic analysis indicates that the thermal decomposition reaction of the lowest eutectic mixture requires endotherm, and the entropy value of the reaction is decreased. Thermo gravimetric mass spectrometry (TG-MS) shows that the main decomposition products of the lowest eutectic mixture are CH4, N2O, CO2, H2, H2O, and only a small amount of NH3, and thermal decomposition of it is more complete than raw materials. Then the mechanical sensitivity of the raw MTNP, TNAZ and the lowest eutectic were tested, and the detonation performance were also calculated, the results show that the lowest eutectic has good mechanical sensitivity and detonation performance. Finally, the thermal sensitivity test was carried out on the raw materials and the lowest eutectic mixture, and it was found that the lowest eutectic mixture had the lowest activation energy, which is more conducive to thermal decomposition. [ABSTRACT FROM AUTHOR]

It has been widely accepted that bulk metallic glasses (BMGs) are usually near deep eutectic compositions. However, the microstructure relationship between eutectic and BMG is still unresolved. The present work is devoted to revealing the atomic short-range-order microstructure similarity of eutectic and BMG. Principal cluster is defined according to atomic close-packing and degree of isolation and then dual-cluster formulas model [(principal cluster)1 + (principal cluster)2](glue atom)2, 4 or 6 is developed to interpret the eutectic and BMG composition, where the two principal clusters are derived from the eutectic-related phases. As a verification, deep eutectic and corresponding BMGs of Cu–Zr binary system are analysed. The study demonstrates that short-range-order microstructure correlation between eutectic and eutectic-type BMG is reflected by eutectic-related principal cluster. Meanwhile, a detailed procedure of design BMGs is established. [ABSTRACT FROM AUTHOR]

Over the last years, there has been a growing number of studies on YSZ-alumina coatings relevant to the field of thermal barrier coatings. These coatings, either in the form of whiskers or particles reinforced, have been shown to have better properties in comparison to conventional counterparts. Apart from other aspects related to coatings, it is interesting to pose the question: is there any interaction between YSZ and alumina particles which would lead to the amelioration of the properties? Therefore, this study was launched to address the microstructural and mechanical features of YSZ-alumina composites. Since examination and detection of the phases that might be formed in the YSZ-alumina binary system would be a difficult task if the samples had been prepared by the common techniques for the coating preparation, Spark Plasma Sintering was employed to achieve dense samples to find a correlation between the microstructure and mechanical properties. [ABSTRACT FROM AUTHOR]

Meloxicam (MLX) is a non-steroidal anti-inflammatory which is practically insoluble in water, requiring high concentrations to reach therapeutic levels and causing frequently gastrointestinal effects. In this way, the aim of this study was to synthesize two eutectic mixtures of MLX with mandelic acid (MND) and saccharin (SAC) by liquid-assisted grinding resulting in a multicomponent material with enhanced solubility. Mixtures were studied in different stoichiometric and eutectic point was found for each eutectic by Binary phase diagram and Tamman's triangle, with 0.33 molar fraction of MLX for SAC and MND. Eutectics were characterized by thermoanalytical techniques (TG-DSC, EGA, DSC, and DSC microscopy), infrared spectroscopy, and X-ray powder diffraction. Thermal behavior was studied and videos of the materials being heated were available. A polymorphic transition was discovered and studied for MLX-MND eutectic. Each new system was evaluated by solubility, dissolution, and hygroscopicity tests. Eutectics showed an increase in solubility of 1.7× (MLX-MND1), 3.1× (MLX-MND2), and 1.3× (MLX-SAC) with slower dissolution profile when compared with MLX. All new solid forms showed high hygroscopicity at 98% relative humidity with 27.9 and 58.9% increase in mass at day four for MLX-SAC and MLX-MND, deliquescence occurs at day 6. The experiments and analysis in this study help to understand the behavior of eutectics and evaluate them as an approach to modify properties in drugs. [ABSTRACT FROM AUTHOR]

Recently, the eutectic composition of organic binary mixtures MENA+DPA has been found to be an efficient stabilizer of nitrocellulose. However, the behavior of such new stabilizer must be further investigated, especially after a long period of storage of the energetic composition. In this study, the stabilizing effect of the eutectic MENA+DPA on NC stability during artificial aging (at 338.65 K for 120 days), compared to its pure components, has been investigated by conventional stability tests and kinetic modeling. According to Bergmann & Junk (T = 405.15 K) results and over the entire period of aging, the eutectic MENA+DPA exhibits the best stabilizing effect on NC. The vacuum stability test (T = 353.15, 363.15, 373.15, and 383.15 K) results revealed that the amount of the evolved gas of NC containing this eutectic composition is very close to that of DPA, known as the conventional stabilizer. Furthermore, the kinetic modeling on VST data, obtained at four isothermal temperatures, was performed by two different methodologies, viz, fitting and free models to determine the kinetic triplets, which have been subsequently used to predict the storage lifetime for the studied systems. It was found that the NC stabilized by the eutectic MENA+DPA presents the highest value of the activation energy and has the longest storage lifetime during the entire heating period corroborating the stability tests results and affirming the excellent stabilizing effect of this mixture with respect to its pure component even if a long storage period is expected. [ABSTRACT FROM AUTHOR]

Damping is the ability to reduce the energy produced by vibrations in a system. In this research, the eutectic high-entropy alloys (EHEAs), AlCoxCrFeNi2.1 (x = 0.7, 1.0 and 1.5), are firstly studied for their damping behaviour. EHEA is a promising concept of high-entropy alloys. By combining the advantages of eutectic phases and HEAs, the EHEAs show better liquidity, castability and compositional homogeneity than conventional HEAs. Meanwhile, it can strike a great balance in mechanical strength and tensile ductility owing to the lamellar structures. The microstructures and crystal structure of two near-EHEAs are also studied. AlCo0.7CrFeNi2.1 is a hypo-eutectic HEA with primary body-centred cubic phases. AlCo1.5CrFeNi2.1 is a hyper-eutectic HEA with primary face-centred cubic phases. The results showed that these eutectic and near-eutectic alloys gave rise to greater tan δ values than conventional dual-phase HEAs, which might be attributed to their lamellar structures. [ABSTRACT FROM AUTHOR]

Ultrasonic velocities have been measured for different binary mixtures of common choline chloride-based deep eutectic solvents (DESs), namely, reline, glyceline and ethaline with water, in the range of temperature: 303.15-353.15 K. The experimental data measurements with different mole fractions of DES-water solutions were utilised in fitting four different models for speed of sound. These models correlate the speed of sound with some physical properties such as molar volumes, molar components sound velocity, densities, molecular weights, collision factors etc. A close match was obtained with these models with an average relative error of less than 4% for all data points used. It was observed that the ultrasonic velocity increases with the concentration of DES solvent and decreases with temperature. Moreover, this study roughly indicated that the intermolecular interactions in reline and ethaline aqueous mixtures exist in the form of disruption of dipole-dipole interactions (that varies considerably as a function of DES mixture composition and solution temperature). On the other hand, the interactions on the molecular level in glyceline aqueous solution are mainly due to dipole-dipole intermolecular forces. [ABSTRACT FROM AUTHOR]

We studied the eutectic behaviour in binary miscible blends of a rigid and two semi-flexible Liquid Crystal Polymers (LCP) model systems for self and thermoplastic reinforcement. At the eutectic point of the studied LCP-LCP blends, the systems showed suppressed crystal-nematic temperatures and wider nematic range with lower process temperature than the single LCP components. This approach broadens the application of LCPs as high-performance polymers, as well as in reinforcement of engineering plastics. The eutectic points of LCP blends could be a blueprint for development of varieties of multi-component LCP materials. [ABSTRACT FROM AUTHOR]

A ZrB2-ZrN eutectic composite was prepared by arc-melting a mixture of ZrB2 and ZrN powders under a N2 atmosphere. The eutectic composition was 48ZrB2-52ZrN (mol%), resulting in a rod-like microstructure comprising hexagonally faceted ZrN single-crystal rods dispersed in a ZrB2 single-crystal matrix. The crystal orientation relationship between the ZrB2 matrix and the ZrN rod was ZrB2//ZrN{101} and ZrB2 <0001>//ZrN <111>. The rod-like eutectic composite had a Vickers hardness of 16.2 GPa. [ABSTRACT FROM AUTHOR]

The expansion/contraction during the solidification of grey cast iron was studied using Linear Variable Differential Transformer (LVDT). The experiments were conducted with and without melt treatment. Two types of inoculant used for melt treatment: ASSC (Si, Ca, Sr & Al) and MBZCAS (Si, Ca, Zr, Ba, Mn & Al). Microstructural investigations carried out to quantify the eutectic cells, undercooled graphite, primary austenite and secondary dendritic arm spacing (SDAS). It was found that the casting shows hardly any shrinkage during early solidification but in the eutectic region, the casting expands until the end of solidification. The measured and the calculated volume changes are close to one another, but the former shows more expansion. The addition of MBZCAS promotes more flake graphite, and ASSC does not increase eutectic cells much. In addition to that, it lowers the primary austenite fraction, promotes more eutectic growth, decreases undercooled graphite and SDAS. As a result, the volume expansion changes in the eutectic region. [ABSTRACT FROM PUBLISHER]

Ternary NaF-LiF-LnF3 (Ln = La, Nd) systems of eutectic compositions were studied by means of X-ray diffraction method in the solid and liquid states. It was found that the crystalline phases LiF, NaF and NaLnF4 coexist in the solid state up to the melting temperatures. Above the melting point, a decrease in the nearest interatomic distances with a pronounced minimum has been observed, which correlates with the extreme behaviour of the temperature-dependent structure-sensitive physical properties of the investigated alloys. [ABSTRACT FROM AUTHOR]

Even with decades of study, the complex development of solidification microstructures in cast iron is incompletely understood. In order to observe the effect of ternary and quaternary alloying additions on the solidification behaviour and graphite spacing of gray iron, directional solidification in a Bridgman furnace was used to carefully control solidification conditions. Specifically, alloys with industrially relevant amounts of silicon and manganese were studied. Average spacings for five compositions, containing varied amounts of Si and Mn, and velocities from 0.5 to 10 μm/s are reported. A critical velocity of around 1 μm/s was observed, above which the graphite structure loses directionality and austenite dendrites appear. Spacing measurements are compared to historical data and a new model, highlighting the importance of sulphur in determining spacing. Spacing measurements obtained in the traditional way were compared to results obtained using a recently developed automated MATLAB algorithm. The automated results compare favourably with traditional manual measurements and will allow for more robust measurement of eutectic spacing in a variety of systems where the spacing is highly irregular. [ABSTRACT FROM PUBLISHER]

Special features of the contact interaction of single-phase brasses with the eutectic melt of the Ga–Zn system as the composite components of gallium pastes–;solders are determined. The products of interaction in relation to the composition temperature of contacting components are investigated. [ABSTRACT FROM AUTHOR]

The paper presents the results of tests on the spheroidising treatment of vanadium carbides VC done with magnesium master alloy and RE. The conducted metallographic studies have shown that introducing the magnesium master alloy to an Fe–C–V system of eutectic composition causes the crystallisation of spheroidal carbides. The content of these carbides is about 5.6%, representing 33% of all the crystallised vanadium carbides. Adding RE to the base alloy melt caused 31% of the vanadium carbides crystallise as dendrites. Testing of mechanical properties has proved that the spheroidising treatment of VC carbides in high-vanadium cast iron increases the tensile strength by about 60% and elongation 14–21 times, depending on the type of the spheroidising agent used. Tribological studies have shown that high-vanadium cast iron with eutectic, dendritic and spheroidal carbides has the abrasive wear resistance more than twice as high as the abrasion-resistant cast steel. [ABSTRACT FROM AUTHOR]

Phase diagram studies of o-nitroaniline-β-naphthol system have been made by the thaw melt method. Simple eutectic type phase diagram was formed. Formation of eutectic mixture occurred at 0.7222 mole fractions of o-nitroaniline and melted at 326.85 K. The heat of fusion of components and eutectic mixtures were determined with the help of DSC technique and excess thermodynamic functions were calculated. Experiments were performed to study the undercooling, microstructure and linear velocities of crystallization. Flexural strength measurements were also made. Eutectic mixture showed higher flexural strength as compared to the components. [ABSTRACT FROM AUTHOR]

The in situ synthesis/consolidation of B4C-TaB2 eutectic composites by spark plasma sintering (SPS) is reported. The microstructure-property relations were determined for composites with the B4C-TaB2 eutectic composition as functions of TaB2 content, and TaB2-TaB2 interlamellar spacing. A clear maximum in fracture toughness was identified (∼4.5 MPa m1/2) for eutectic composites with interlamellar spacing between 0.9 and 1.1 μm. The composites with the hypereutectic composition of 40 mol.% TaB2 obtained by SPS exhibited lower Vickers hardness (25-26 GPa) but higher indentation fracture toughness (up to 4.9 MPa m1/2) than eutectic composites with 30-35 mol.% of TaB2. [ABSTRACT FROM AUTHOR]

An account is given of the work needed to take the cyanobiphenyl liquid crystal (LC) series invented by George Gray and his colleagues and formulate them into ready-to-use mixtures required by display manufacturers. Two classes of formulated mixtures are described. Static addressed displays typical of those used in industrial and instrument displays as well as the first LC watches required mixtures with wide operating temperature ranges from at least −10°C up to 60–100°C. Later, mixtures optimised for multiplex drive made possible the more complex displays used in later watches, calculators and other alphanumeric devices. The principles involved and the difficulties encountered in formulating the mixtures are described. All of the mixtures used in practice required the use of other materials mixed with the simple cyanobiphenyls, and the essential part played in mixture development by these other materials, many of which originated in George’s research group, is highlighted. [ABSTRACT FROM PUBLISHER]

Phase diagram studies of succinonitrile-vanillin system show the formation of 2:1 congruent melting type compound. Crystallization velocities of pure components, succinonitrile-vanillin complex, and two eutectics have been determined at different undercoolings. On the basis of heat of fusion measurements, excess thermodynamic functions have been calculated. Microstructural studies revealed that impurities modify the morphology. FTIR spectral studies and computer simulation have shown the existence of hydrogen bonding in the eutectics and the congruent melting compound. On the basis of experimental results, the mechanism of formation of eutectics and its solidification behavior are discussed. [ABSTRACT FROM AUTHOR]

This study is aimed toward obtaining near spherical microstructural features of Rheocast A380 aluminum alloy. Cooling slope (CS) technique has been used to generate semisolid slurry from the superheated alloy melt. Spherodization of primary grains is the heart of semisolid processing which improves mechanical properties significantly in the parts cast from semisolid state compared to the conventional casting processes. Keeping in view of the desired microstructural morphology, i.e., rosette or spherical shape of primary α-Al phase, successive slurry samples have been collected during melt flow and oil quenched to investigate the microstructure evolution mechanism. Conventionally cast A380 Al alloy sample shows dendritic grains surrounded by large eutectic phase whereas finer, near spherical grains have been observed within the cooling slope processed slurry and also in the solidified castings which confirms the effectiveness of semisolid processing of the alloy following cooling slope technique. Grain refiner addition into the alloy melt is found to have favorable effect which leads to the generation of finer primary grains within the slurry with higher degree of sphericity. [ABSTRACT FROM PUBLISHER]

The results of the investigation of the influence of different modifiers (sodium, phosphorus, antimony and strontium) on the quality of AlSi12CuMgNi and AlSi18CuMgNi alloys, which are used for the production of pistons, are presented in this paper. The effects of these elements were investigated with reference to their mechanical and structural properties measured at ambient and elevated temperatures and service performance of the piston. Since strontium and antimony modified alloys are not considered as standardised piston alloys, the research results were compared with the results of standard phosphor and sodium modified alloys normally used at globally renowned piston manufacturer: Mahle, KS. [ABSTRACT FROM AUTHOR]

Drug-in-adhesive acrylic films, containing binary mixtures of ibuprofen:poloxamer 188 in 30:70, 40:60, 50:50, and 60:40 ratios, were prepared by incorporation either as physical mixture (PM), molten mixture (MM), or solid dispersion (SD). Dissolution testing showed that films prepared by MM had higher drug release compared to films prepared by PM, SD, and films containing ibuprofen alone. The MM 50:50 ratio showed the highest drug release ( p < 0.05). Examination of the films by differential scanning calorimetry showed melting endotherms from the binary crystalline mixture but not from ibuprofen crystals regardless of the preparation method. Rheological measurements showed that MM films had lower elastic moduli compared to the neat adhesive, due to the plasticizing effect of the dissolved binary mixture. Fourier transfer infrared analysis confirmed the absence of ibuprofen crystal dimers in all films. It was therefore concluded that the MM method provided better mixing of the components providing crystal-free supersaturated films of high thermodynamic activity. [ABSTRACT FROM AUTHOR]

Composition formulae for ideal metallic glasses are explored by combining the cluster-plus-glue-atom model with the global resonance model, termed the cluster-resonance model for short. The former model gives the [cluster]1(glue atom)x cluster formulae, stressing the local cluster order of a glassy structure; the latter model extends the local cluster order to a medium-range one by introducing spherical periodicity that relates the cluster size with Fermi vector, kF. Such a correlation allows the calculation of Fermi energy, EF, and electrochemical potential of electrons of the system from any local clusters. The cluster-resonance model also implies the equilibrium of the electrochemical potentials of electrons between different clusters so that the number of glue atoms matching one cluster (x in the cluster formula) can be determined. Examples in the Cu-Zr-Al and B-Co-Si-Ta systems are given to show the effectiveness of the proposed model and the resulting cluster formulae in interpreting multicomponent metallic-glass compositions as well as their relevant binary eutectic points. [ABSTRACT FROM AUTHOR]

The purpose of this study was to gain a better understanding of which factors contribute to the eutectic composition of drug-polyethylene glycol (PEG) blends and to compare experimental values with predictions from the semi-empirical model developed by Lacoulonche et al. Eutectic compositions of various drug-PEG 3350 solid dispersions were predicted, assuming athermal mixing, and compared to experimentally determined eutectic points. The presence or absence of specific interactions between the drug and PEG 3350 were investigated using Fourier transform infrared (FT-IR) spectroscopy. The eutectic composition for haloperidol-PEG and loratadine-PEG solid dispersions was accurately predicted using the model, while predictions for aceclofenac-PEG and chlorpropamide-PEG were very different from those experimentally observed. Deviations in the model prediction from ideal behavior for the systems evaluated were confirmed to be due to the presence of specific interactions between the drug and polymer, as demonstrated by IR spectroscopy. Detailed analysis showed that the eutectic composition prediction from the model is interdependent on the crystal lattice energy of the drug compound (evaluated from the melting temperature and the heat of fusion) as well as the nature of the drug-polymer interactions. In conclusion, for compounds with melting points less than 200°°C, the model is ideally suited for predicting the eutectic composition of systems where there is an absence of drug-polymer interactions. [ABSTRACT FROM AUTHOR]

Hypereutectic Al–Si alloys that contain more than 3 wt-%Mg exhibit a microstructure that consists of eutectic Si and Mg2Si in α-Al matrix that is devoid of primary silicon particles. The Mg2Si phase is desirable in the Al–Si microstructure because of its high melting temperature, low density, high hardness, low coefficient of thermal expansion and high elastic modulus. However, at such relatively high concentrations of Mg, the Mg2Si phase tends to be in a morphology that detracts from the alloys' mechanical properties. Several chemical modifiers were added to the alloy in order to refine the morphology of the Mg2Si phase. A combination of strontium and misch metal was found to yield the best results in that the microstructure obtained after a standard T6 heat treatment exhibits almost spherical Mg2Si particles. Tensile test bars cast from the modified alloy in steel moulds have very good room temperature tensile properties and good hardness. [ABSTRACT FROM AUTHOR]

Methods: The thermodynamic, eutectic, and crystalline properties of ibuprofen and ketoprofen binary mixtures were investigated using differential scanning calorimetry (DSC) and X-ray powder diffractometry (XRPD). Results: The DSC studies showed that melting point (61°C), enthalpy (11.3 kJ/mol), and entropy of fusion (33.7 J/K/mol) of the binary eutectic were significantly lower than those of the individual anti-inflammatory drugs (NSAIDs). Due to the melting-point depression and enhanced skin lipid solubility, the steady-state flux of ibuprofen and ketoprofen from preparations of the binary eutectic increased as compared to pure NSAIDs using shed snakeskin as a model membrane. The NSAID membrane flux values were calculated by flux ratio equations based on drug thermodynamic data, and compared to experimental values obtained from permeation studies. Conclusion: The proposed flux ratio equations correctly predicted flux increase. [ABSTRACT FROM AUTHOR]

A review of the principal results obtained in the laboratory of metallurgy of the University of Trento is presented in this article. The correlations between heat treatment, surface engineering, microstructure, and properties of hot work and high speed steels in a wide range of applications were evaluated. The basic damage mechanisms of tools and dies were illustrated. The thermal cracking (heat checking) occurring in hot work tool steels for casting/forging dies and in high speed steel work rolls was studied by means of a customary thermal fatigue test. The corrosion by molten metal in die casting dies has been studied by immersion in liquid aluminium. The tribological properties of dies during aluminium hot extrusion were analyzed using a specific simulation test. [ABSTRACT FROM AUTHOR]

Phase diagram of benzoic acid (BA)-o-chloro benzoic acid (o-CBA) system has been studied by thaw melt method and the results show the formation of a simple eutectic mixture. Heats of fusion values of the components and eutectic mixture were determined with the help of differential scanning calorimeter. Excess Gibb's free energy (GE), excess enthalpy (HE), and excess entropy (SE) of mixing of pre-, post-, and the eutectic mixture were calculated. FT-IR spectroscopic studies and ab initio calculations were done to have an idea about the nature of interaction between the molecules in the eutectic mixture. Linear velocities of crystallization of the two components and the eutectic mixture were determined at different undercoolings. Microstructural studies of BA and o-CBA showed the formation of broken lamellar and lamellar type microstructure, whereas for the eutectic mixture growth of flat crystals in different directions from a particular point was obtained. The isotropic as well as the anisotropic solidification behavior was studied. Jackson's roughness parameter was calculated. Modulus of ruptures of pure components and the eutectic mixture were determined. Results show that eutectics are nonideal mixtures, and some weak interactions are involved between the two components. [ABSTRACT FROM AUTHOR]

A number of papers and research projects suggest that stranded natural gas can be transported in a solid hydrate state at higher temperatures or lower pressures compared to conventional transportation systems (LNG and CNG). The self-preservation effect of methane hydrate can probably be improved by the use of a third component besides CH4 and water. Tetrahydrofuran (THF) is a promoter that greatly reduces the required formation pressures. In the present work the influence of THF on the decomposition kinetics of mixed THF-CH4 hydrates was studied to evaluate the THF stabilization effect. The experimental work, carried out with the help of a reaction calorimeter, has revealed that the dissociation rate of mixed THF hydrates is lower (on average by one order of magnitude) than that of simple methane hydrates. Mixed hydrates can also be stored for short periods at temperatures over 0°C. However, the best preservation conditions (among the experimented ones) are realized at -1°C and 3 MPa. (about 66 days required for complete dissociation). [ABSTRACT FROM AUTHOR]

The modified adsorption isotherm model, incorporating the Stokes-Robinson modification of the Brunauer-Emmett-Teller (BET) adsorption isotherm, is used to calculate the activity of the organic acid and water, and the liquidus curve. This is the first known use of the modified adsorption isotherm for estimation of thermodynamic information for aqueous organic acid solutions and one of few works using the model for predicting information for aqueous acids in general. The method described here represents a simplified approach to estimating thermodynamic properties. The model offers some improvement over regular solution theory, but perhaps more importantly offers a method for adjusting thermodynamic properties in the presence of other components in the future. While other models such as UNIQUAC may prove to be more accurate, this model provides satisfactory results with more ease. [ABSTRACT FROM AUTHOR]

The electrolytic deposition of nickel is demonstrated using a solution of the metal chloride salt separately in either a urea or ethylene glycol/choline chloride based ionic liquid. It is shown that the deposition kinetics and thermodynamics differ from the aqueous processes and these result in different deposit morphologies. It is also shown for the first time that bright metal coatings can be obtained from these liquid systems by adding various brightening agents and deposits can be put directly onto substrates such as aluminium without prior treatment. The general mechanism by which brighteners function in ionic liquids is also discussed. [ABSTRACT FROM AUTHOR]

An Al85Ni10La5 amorphous alloy, produced via gas atomization, was selected to study the mechanisms of nanocrystallization induced by thermal exposure. High resolution transmission electron microscopy results indicated the presence of quenched-in Al nuclei in the amorphous matrix of the atomized powder. However, a eutectic-like reaction, which involved the formation of the Al, Al11La3, and Al3Ni phases, was recorded in the first crystallization event (263°C) during differential scanning calorimetry continuous heating. Isothermal annealing experiments conducted below 263°C revealed that the formation of single fcc-Al phase occurred at 235°C. At higher temperatures, growth of the Al crystals occurred with formation of intermetallic phases, leading to a eutectic-like transformation behaviour at 263°C. During the first crystallization stage, nanocrystals were developed in the size range of 5 ∼ 30 nm. During the second crystallization event (283°C), a bimodal size distribution of nanocrystals was formed with the smaller size in the range of around 10 ∼ 30 nm and the larger size around 100 nm. The influence of pre-existing quenched-in Al nuclei on the microstructural evolution in the amorphous Al85Ni10La5 alloy is discussed and the effect of the microstructural evolution on the hardening behaviour is described in detail. [ABSTRACT FROM AUTHOR]

The In1-xBix (x = 0.40, 0.34, 0.23, 0.13, 0.09) molten alloys have been studied by means of viscosity measurements and X-ray diffraction method. Temperature dependence of viscosity coefficient shows the Arrhenius like behavior with anomalous in form of local maximum and significant scattering of experimental values. The features in temperature dependencies of viscosity coefficient were studied also by means of X-ray diffraction method. [ABSTRACT FROM AUTHOR]

A stochastic simulation of solidification is presented, which accounts for atom attachment kinetics at the solid/liquid interface and the effect of capillary force in addition to diffusional or convectional transport of atoms in the melt. The influence of atomic processes at or near the interface on the evolution of a range of solidification microstructure for single phase and coupled growth has been examined using the model. The importance of capillary forces and surface energy anisotropy on dendritic and regular lamellar eutectic growth is explored. Finally, effects of alteration of diffusion geometry near the solid/liquid interface under strong convection on the modification of both single phase and eutectic microstructures are studied. [ABSTRACT FROM AUTHOR]

The Stokes‐Robinson modification of the Brunauer‐Emmett‐Teller (BET) adsorption isotherm is used to calculate the liquidus curve of NaNO 3 (aq) including the eutectic point and metastable phases. The method described here represents a simplified approach to predict the liquidus curves with sparse information and considers the presence of several crystalline solid phases of NH 4 NO 3 . [ABSTRACT FROM AUTHOR]

Using different experimental techniques, microstructure, electrical resistivity, attenuation coefficient, and mechanical and thermal properties of the quenched Bi–Pb–Sn ternary eutectic alloy have been investigated. From the X-ray analysis, Bi 3 Pb 7 and Bi–Sn meta-stable phases are detected, in addition to rhombohedral bismuth and Sn body-centered tetragonal phases. This study also compared the physical properties of the Bi–Sn–Pb ternary eutectic alloys with the base binary Bi–Sn and Bi–Pb eutectic alloys. [ABSTRACT FROM AUTHOR]

Two V-8 engine blocks with cast-in grey iron liners were cast from a heat-treatable aluminium alloy. These blocks were instrumented by the insertion of 24 type K thermocouples placed at different points in the casting to record the thermal evolution during solidification. One of the blocks was cast after heating up the liners by induction, whereas the second was cast without the use of induction heating. The temperature–time readings from the thermocouples were obtained for thermal analysis. The solidification reactions detected were the formation of primary pre-eutectic aluminium dendrites, and two different eutectics that corresponded to Al–Si and complex Al–Si–Mg–Cu aggregates. It was found that the different solidification reactions were affected by the use of induction to heat up the liners, and by the chilling effect caused by a grey iron inset located at the bottom of the engine block moulds. The results indicate that solidification starts either at the window (bottom) or deck (top) positions in the interliners depending on whether the block was cast with or without the use of induction heating. [ABSTRACT FROM AUTHOR]