Eutectic Melting Point Research Articles

Synthesis and characterizations of random copolyamide PA(56-co-66): Excellent toughness and transparency

Random copolyamides PA(56-co-66) (coPA-n) with various comonomer compositions were synthesized by a one-pot polycondensation reaction of pentamethyleneammonium adipate (PMA) salt and hexamethyleneammonium adipate (HMA) salt in aqueous solution. All copolymers have high Mn (≥15000 g/mol). The molecular segment composition can be regulated by controlling the feed ratio of PMA salt and HMA salt. Tc and Tm of copolymers obtained by nonisothermal crystallization depend on the composition, showing a clear pseudo-eutectic behavior. Copolyamide coPA-50 exhibits a eutectic phenomenon with the melting point decreasing to a minimum of 218.9 °C. WAXD and SAXS results confirm that the crystalline structure of the copolyamides follows that of the rich component, exhibiting a typical isodimorphic characteristic. Mechanical properties of the copolyamides indicate that the elongation at break could be improved significantly with slight sacrifice of strength, which provides a promising approach for fabricating polyamide materials with desired properties. The tensile strength, tensile modulus, and elongation at break of coPA-50 was 65.2 MPa, 1.0 GPa, and 758.1 %, respectively. These copolymers can be melt-spun into fibers with excellent mechanical properties. Especially, the transmittance of coPA-60 reaches a high value of 88.01 % due to its low crystallinity and small crystal size.

INVESTIGATION OF THE NA+, K+ || VO3–, SO42– TERNARY RECIPROCAL SYSTEM AND MEASUREMENT OF THE NONVARIANT COMPOSITIONS MELTING ENTHALPY

Functional compositions based on multicomponent systems of oxygen-containing salts of s1-elements are widely used in various fields of industry, science and technology: electrometallurgy of light, refractory and heavy metals, as well as metallothermy, pyrometallurgy, promising fluxes for welding and soldering metals, chemical power sources. In the work the triangulation of the Na+, K+ || VO3–, SO42– ternary reciprocal system of sulfates and metavanadates of sodium and potassium on simplices was carried out. The phase states of the Na+, K+ || VO3–, SO42– ternary reciprocal system was investigated by differential thermal analysis (DTA). T–x diagram of the stable secant K2SO4–NaVO3 was constructed, which is the diagonal of the system composition square and which has a eutectic with a melting point of the quasi-double eutectic of 575 °C and a specific melting enthalpy value of 206 kJ/kg. In the NaVO3–Na2SO4–K2SO stable triangle, a minimum of solid solutions with a temperature of 559 °C and an enthalpy of 190 kJ/kg was determined. In the NaVO3–KVO3–K2SO4 stable triangle, the three-component eutectic with a minimum melting point in the system of 474 °C has a minimum specific melting enthalpy of 183 kJ/kg. Compositions of the triple peritectic Р 482 °С and the three-component minimum of solid solutions M 559 °С were determined. The maximum crystallization fields of the system composition square correspond to potassium sulfate and continuous solid solutions of sodium and potassium sulfates. Low-melting mixtures of quasi-double eutectic, ternary eutectic, and ternary minimum can be used as molten electrolytes for medium-temperature chemical current sources and as heat storage materials. For citation: Istomova M.A., Garkushin I.K. Investigation of the Na+, K+ || VO3–, SO42– ternary reciprocal system and measurement of the nonvariant compositions melting enthalpy. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 6. P. 38-44. DOI: 10.6060/ivkkt.20246706.6983.

Recoverable tuning of lattice mismatch and strength in ultrastable-nanostructured Cu/Ag spinodoid alloys

The strengthening effect of interface in materials is usually studied by monitoring the change of strength in response to varying structure sizes, such as the varying grain or phase sizes. In this study, we demonstrate that the strength of a nanostructured material can be recoverably tuned by modifying interfacial structure without changing structure size. Specifically, we studied the Cu/Ag spinodoid alloys fabricated by dealloying and electrochemical deposition, which exhibit a cube-on-cube orientation relationship between two interpenetrating nanophases. This material remains stable against coarsening even at temperatures near the eutectic melting point, due to the presence of low-energy semi-coherent interfaces and the lack of defects such as grain boundaries. Using cyclic thermal annealing, we are able to alter the solid solubility of both nanophases and, consequently, the lattice mismatch between them, resulting in a recoverable tuning of hardness and strength. The amplitude of hardness modulation decreases with increasing feature size (λ), and changes sign when λ exceeds ∼500 nm. This is attributed to a competition between two strengthening mechanisms: the interface-induced strengthening that is more prominent at a lower λ, and the solid solution hardening that is largely λ-insensitive. The finding indicates that interface hardening prevails over solution hardening when λ is below ∼500 nm. Current study paves the way for the development of strong and stable nanostructured materials whose properties can be optimized by independently tailoring feature sizes and interfacial structures.

Spontaneous formation of Au-Co interface via a Low-Temperature reduction process

Eutectic alloys manufactured by metallurgical methods are widely used in many industrial applications due to their special properties provided by the multi-phase eutectic microstructure. Previous studies introduced the preparation of metals and alloys through the chemical reduction of metal complex salts. We employed this technique to prepare the equiatomic composition in the binary eutectic system Au-Co through a low-temperature solid-gas phase reduction of two precursors: the bi-metallic complex salt [Co(NH3)6][AuCl4]Cl2, and an equimolar mixture of H[AuCl4] and pre-reduced cobalt. Complete reduction at 350 °C resulted in the formation of a close-to-equilibrium two-phase composition of fcc gold and hcp cobalt. The structure of the fully reduced metallic materials was composed of interconnected cobalt ligaments and bi-metallic Au-Co (gold-cobalt) particles. Specifically, these spontaneously formed particles featured fcc cobalt islands interfacing with fcc gold at a specific orientation relationship. Under heating, the fully reduced Au-Co products underwent melting that corresponds to the equilibrium eutectic melting point at 996.5 °C. These results imply that spontaneous lattice self-adjustment can occur in multi-component eutectic-type systems at low temperatures directly in the solid state. This may ease the technologies of joining such as epitaxial growth, additive manufacturing, and powder metallurgy.

A two-step strategy for production of spherical non-aggregated multi-component particles by suspension-fed spray flame

For applications in optics, energy storage, and semiconductors etc., spherical non-aggregated particles are desired for better flowability, molding capability and homogeneous densification. Spray flame synthesis has attracted widespread attention with its excellent ability for atomic-level mixing/doping and good potential for scale-up production. However, spray flame synthesis usually produces aggregates due to the known collision-coalescence growth. In this paper, we propose a two-step strategy of suspension-fed spray-flame synthesis. The first step involves the synthesis of aggregated nanoparticles, followed by a second step where these aggregates are reconstructed into spherical non-aggregated particles while retaining the advantage of atomic-level homogeneous mixing. It is found that for aggregated Y2O3 nanoparticles, the critical point for reconstructing into spherical particles occurs when the flame temperature exceeds the melting point. The spherical particle size increases with the solid concentration of the suspension by a power of about 0.28. Assuming that droplets do not undergo micro-explosions and instead follow a one droplet to one particle route results in an overestimation of particle size by a factor of 6 to 8. This discrepancy suggests that micro-explosions may play certain role in the new suspension-fed flame synthesis, and largely reduces the final particle size. Furthermore, the Al2O3-Y2O3 and MgO-Y2O3 particles are selected for the multicomponent suspension-fed synthesis, representing the miscible and immiscible systems, respectively. The results show that for the Al2O3-Y2O3 system, uniformly mixed spherical non-aggregated particles are obtained. For the MgO-Y2O3 system, both composite spherical particles with pinning structure and MgO nanoparticles are identified, indicating that for obtaining spherical multi-component non-aggregated particles, the flame temperature needs to be higher than not only the eutectic component's melting point but also any single component's melting point. Overall, suspension-fed spray flame synthesis opens up a new pathway for the low-cost industrial-scale production of spherical non-aggregated multi-component particles.

Energizing eutectic salt hydrate phase change material using 2D carbon based graphene nanoparticle

Energy being the strongly depended source for development and industrialization, their storage in any form tends to bridge the gap between demand and supply. Renewable energy technology systems now include energy storage as a crucial component. Thermal energy storage is a technique that stores thermal energy by heating or cooling a storage medium. This allows the energy to be used for heating and cooling purposes later on. The present study develops ternary inorganic salt hydrate eutectic phase change material (EPCM) that is intended for cooling buildings. Melting temperature, melting enthalpy and eutectic composition proportion of inorganic salt hydrate of sodium carbonate decahydrate (SCD), sodium phosphate dibasic dodecahydrate (SPDD), and sodium sulphate decahydrate (SSD) are determined using the eutectic melting point theory. Ternary EPCM is synthesised experimentally in accordance with the percentage of salt hydrates. Graphene nanoplatelets are distributed at different weight concentrations of 0.3%, 0.6%, and 0.9% in order to further improve the thermal performance; at higher concentration above 0.9% the graphene nanoplatelets tends to agglomerate. In order to assess the chemical stability and thermal properties of prepared nanoparticle dispersed PCMs, are experimentally assessed. Findings confirm the ternary EPCM's chemical stability and raise its latent heat with graphene nanoplatelets.

Glass forming ability and phases of (Li,Na)acetate salt mixtures

Anhydrous mixtures of lithium acetate and sodium acetate were investigated by differential scanning calorimetry and X-ray powder diffraction. A tentative phase diagram is derived from these data. The Li1-xNaxCH3COO system has a eutectic for the NaCH3COO molar fraction of x≈0.55. The relatively low eutectic melting point at 448 K (175 ∘C) may make this composition an interesting molten salt solvent. Peritectic reactions correspond to phases with compositions near Li4Na(CH3COO)5 and LiNa3(CH3COO)4. On the Li-rich side of the eutectic, the system, prepared as a glass, can crystallized deliberately. This allows checking the data validity with the first law of thermodynamics. The stability range of the supercooled liquid increases with x up to Li0.55Na0.45CH3COO. For higher sodium concentrations, the samples remain mixtures of glass and crystalline phases, with the amount of the vitreous component decreasing linearly from x = 0.45 to x = 1. The fragility of the liquid state, highest for pure LiCH3COO, decreases by a factor of two over the range 0<x<0.2, and remains constant for higher x.

Expanded graphite intersperse reliable binary eutectic phase change material for low temperature thermal regulation systems

Inorganic phase change materials (PCMs) frequently stuck by ineffaceable thermal conductivity and degree of supercooling for thermal energy storage (TES) accomplishment. The present research work is dedicated to resolve this problem by developing a unique inorganic salt hydrate based binary eutectic PCM employing sodium sulphate decahydrate (SSD) and sodium phosphate dibasic dodecahydrate (SPDD) in eutectic mixture ratio 62:38 mass percentage. The peculiar eutectic composition of SSD/SPDD developed with melting and bath sonication technique manifests eutectic latent heat of 207.4 J/g and eutectic melting point of 27.8 °C. Furthermore, to elevate thermal performance and to descent degree of supercooling three dimension expanded graphite (EG) is interspersed as nanoparticle. Optical absorbance of composite PCM elevated from 0.16 for SSD/SPDD to 0.92 with SSD/SPDD + EG nanoparticles; inversely transmissibility of the composite reduced by 82.13 %. Heat flow curves ensures the melting temperature (26.9 °C–28.7 °C) of EG dispersed composite to be within the operating condition with latent heat of 220.4 J/g at 2.0 % of EG owing to the intermolecular binding force of attraction increases as nano-sized sheets effectively disperse with the base PCM. Subsequently, thermal conductance of nano composite eutectic PCM upraised from 0.453 to 0.855 W/m⋅K. After 200 thermal cycle's chemical optical and thermal stability of the PCM composite was degraded insubstantially due to the presence of impurities with longer service; this affirmed the stability thermal perks of nanocomposite PCM. Numerical analysis on heat transfer propagation of heat source within SSD/SPDD PCM layer with and without EG nanoparticle provides inference on the importance of thermal conductivity.

Electrical properties of iron sulfide-bearing dunite under pressure: Effect of temperature, composition, and annealing time

Abstract The detection and quantification of metal sulfides in host rocks by electrical measurements have been priorities for field and laboratory studies, motivated by mineral prospecting and fundamental interest in the mantle structure or core/mantle differentiation, among other reasons. Here, we reanalyze electrical data for a dunite host with added FeS or Fe-S-Ni (Saxena et al. 2021), and report additional experimental runs along with electron microprobe analyses. The applied pressure was 2 GPa; impedance spectra were acquired while annealing at 1023 K (below the metal-sulfide solidus), and while varying temperature from 570 to 1650 K. Addition of 6.5 or 18 vol% FeS strongly enhances conductivity of the bulk sample compared with that of the dunite host, though values are 100–100 000 times less than those of pure FeS. These results indicate that most metal sulfide content is not part of a viable conductive path, even for the 18 vol% quantity. Nevertheless, the relatively high conductivity and weak temperature dependence of the 18 vol% sample reveal that contiguous paths of solid or molten FeS span the electrodes. The sample with 6.5 vol% sulfide also exceeds the percolation threshold for temperatures as low as ~100 K below the eutectic melting point, likely because FeS softens. Conductivity is nearly unchanged upon crossing the eutectic temperature, however a decline over 1400–1500 K reveals that the 6.5 vol% molten FeS forms a fragile electrical network in dunite. Samples with Fe50S40Ni10 or Fe40S40Ni20 (at%) are less conductive than pure dunite at temperatures below ~1450 K. This surprising result, likely caused by a reducing influence of Fe or Ni metal, does not support the use of FeS as an analog for compositions with nickel or excess metal. Our findings suggest that probing the electrical network of metal sulfides as solids complements other studies focused on connectivity of molten metal sulfides.

Physical properties of natural deep eutectic solvent and its application in remediation of heavy metal lead in soil

At present, solvent extraction is an effective method to remove heavy metals from soil, which has certain practical significance. The physical properties such as density, viscosity and conductivity of NADESs with different proportions synthesized based on the double solid components of glycolic acid (GA) and L-proline (L-PRO) and the physical properties of NADESs aqueous solution at the lowest eutectic point (3:1) were studied. The extraction effect of NADESs on soil heavy metal Pb2+ under different conditions was studied. The results showed that under the conditions of atmospheric pressure of 101.33 kPa, the lowest eutectic melting point, DESs concentration of 0.6 mol·L−1, extraction temperature of 313.15 K and extraction time of 4 h, the extraction rate of Pb2+ by NADESs was 95.28%. In addition, the internal structure of DESs was characterized by IR and NMR, which indicated that intermolecular hydrogen bonds were formed. and the interaction between DESs and Pb2+ was analyzed by quantum chemical calculation, which showed that the hydroxyl group of GA was more likely to form coordination bond with Pb2+, and chelation occurred between them. This kind of DESs provides a new idea for the removal of heavy metals in soil.

Large Decrease in the Melting Point of Benzoquinones via High-n Eutectic Mixing Predicted by a Regular Solution Model.

Decreasing the melting point (Tm) of a mixture is of interest in cryopreservatives, molten salts, and battery electrolytes. One general strategy to decrease Tm, exemplified by deep eutectic solvents, is to mix components with favorable (negative) enthalpic interactions. We demonstrate a complementary strategy to decrease Tm by mixing many components with neutral or slightly positive enthalpic interactions, using the number of components (n) to increase the entropy of mixing and decrease Tm. In theory, under certain conditions this approach could achieve an arbitrarily low Tm. Furthermore, if the components are small redox-active molecules, such as the benzoquinones studied here, this approach could lead to high energy density flow battery electrolytes. Finding the eutectic composition of a high-n mixture can be challenging due to the large compositional space yet is essential for ensuring the existence of a purely liquid phase. We reformulate and apply fundamental thermodynamic equations to describe high-n eutectic mixtures of small redox-active molecules (benzoquinones and hydroquinones). We illustrate a novel application of this theory by tuning the entropy of melting, rather than the enthalpy, in systems highly relevant to energy storage. We demonstrate with differential scanning calorimetry measurements that 1,4-benzoquinone derivatives exhibit eutectic mixing that decreases their Tm, despite slightly positive enthalpies of mixing (0-5 kJ/mol). By rigorously investigating all 21 binary mixtures of a set of seven 1,4-benzoquinone derivatives with alkyl substituents (Tm's between 44 and 120 °C), we find that the eutectic melting point of a mixture of all seven achieves a large decrease in Tm to -6 °C. We further determine that the regular solution model shows improvement over an ideal solution model in predicting the eutectic properties for this newly investigated type of mixture composed of many small redox-active organic molecules.

NaNO3-KNO3-KCl/K2CO3 with the elevated working temperature for CSP application: Phase diagram calculation and machine learning

Mixed nitrates with relative low melting point have widely been used as thermal storage medium in the concentrated solar power stations. However, their maximum working temperatures aren’t high enough to integrate with more efficient power generation systems such as the supercritical CO2 cycle. In the present work, mixed nitrates with elevated working temperature were obtained by adding KCl/K2CO3. With the help of FactSage software and back-propagation (BP) algorithm combined with genetic algorithm (GA), the eutectic compositions and melting points of NaNO3-KNO3-KCl and NaNO3-KNO3-K2CO3 were predicted, and the validity of BP algorithm combined with GA was verified. Based on DSC and TG curves, the melting points of the as-prepared NaNO3-KNO3-KCl and NaNO3-KNO3-K2CO3 are 206.12 °C and 207.24 °C, respectively, which are in agreement with predicted values. Moreover, their decomposition temperatures were increased to more than 640 °C. In addition, the specific heat capacity of both mixed molten salts was measured, and it also was calculated by using FactSage software. This work provides two new ternary molten salts based on nitrates with higher working temperature and develops the prediction method on phase diagram calculation and machine learning.

Experimental Investigation of Graphene Nanoplatelets Enhanced Low Temperature Ternary Eutectic Salt Hydrate Phase Change Material

A sustainable approach to ensuring the thermal regulation of space is reliable with phase change materials (PCMs) operating at 15–25 °C. Henceforth, there is a need of a search of binary and ternary eutectic PCMs operating at desirable phase transition temperatures of 15–25 °C, high energy storage enthalpy (180–220 J/g), improved thermal conductivity and better absorptivity of solar energy. In this current research, we developed a ternary eutectic inorganic salt hydrate PCM intended for a low-temperature thermal regulation system. Based on the eutectic melting point theory, the phase transition temperature and proportion of sodium carbonate decahydrate (SCD), sodium phosphate dibasic dodecahydrate (SPDD) and sodium sulphate decahydrate (SSD) were determined. As per the calculated proportion, ternary eutectic PCM was experimentally prepared. Furthermore, to enhance the thermal property, graphene nanoplatelets (GNP) were dispersed at weight concentrations of 0.4%, 0.7% and 1.0%. The prepared nanoparticle-dispersed PCMs were characterized using an optical microscope, Fourier transform infrared (FT-IR) spectroscopy and a thermal conductivity meter, and a differential scanning calorimeter (DSC) was used to evaluate the morphology, chemical stability and thermal properties. The results showed increases in thermal conductivity and optical absorbance by 71.5% and 106.5%, respectively, with GNP at 1.0% weight concentration. Similarly, the degree of supercooling and transmissibility was reduced by 43.5% and 76.2% correspondingly. The prepared composite PCM is expected to contribute towards cooling, with an intention to contribute towards sustainable development.

Eutectic Mixture Formation and Relaxation Dynamics of Coamorphous Mixtures of Two Benzodiazepine Drugs

The formation of coamorphous mixtures of pharmaceuticals is an interesting strategy to improve the solubility and bioavailability of drugs, while at the same time enhancing the kinetic stability of the resulting binary glass and allowing the simultaneous administration of two active principles. In this contribution, we describe kinetically stable amorphous binary mixtures of two commercial active pharmaceutical ingredients, diazepam and nordazepam, of which the latter, besides being administered as a drug on its own, is also the main active metabolite of the other in the human body. We report the eutectic equilibrium-phase diagram of the binary mixture, which is found to be characterized by an experimental eutectic composition of 0.18 molar fraction of nordazepam, with a eutectic melting point of Te = 395.4 ± 1.2 K. The two compounds are barely miscible in the crystalline phase. The mechanically obtained mixtures were melted and supercooled to study the glass-transition and molecular-relaxation dynamics of amorphous mixtures at the corresponding concentration. The glass-transition temperature was always higher than room temperature and varied linearly with composition. The Te was lower than the onset of thermal decomposition of either compound (pure nordazepam decomposes upon melting and pure diazepam well above its melting point), thus implying that the eutectic liquid and glass can be obtained without any degradation of the drugs. The eutectic glass was kinetically stable against crystallization for at least a few months. The relaxation processes of the amorphous mixtures were studied by dielectric spectroscopy, which provided evidence for a single structural (α) relaxation, a single Johari-Goldstein (β) relaxation, and a ring-inversion conformational relaxation of the diazepinic ring, occurring on the same timescale in both drugs. We further characterized both the binary mixtures and pure compounds by FTIR spectroscopy and first-principles density functional theory (DFT) simulations to analyze intermolecular interactions. The DFT calculations confirm the presence of strong attractive forces within the heteromolecular dimer, leading to large dimer interaction energies of the order of -0.1 eV.

Biobased Copolyamides 56/66: Synthesis, Characterization and Crystallization Kinetics.

This study synthesized a series of new biobased copolyamides (co-PAs), namely PA56/PA66 with various comonomer ratios, by using in situ polycondensation. The structures, compositions, behaviors, and crystallization kinetics of the co-PAs were investigated through proton nuclear magnetic resonance (1H NMR) spectroscopy, gel permeation chromatography (GPC), Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), polarized optical microscopy (POM), and X-ray diffraction (XRD). The influence of the composition of co-PAs on their mechanical properties and thermal stability was investigated. The co-PAs exhibited a eutectic melting point when the PA56 content was 50 mol%, with the crystallization temperature decreasing from 229 to a minimum 188 °C and the melting temperature from 253 to a minimum 218 °C. The results indicated that the tensile strength and flexural modulus first decreased and then increased as the PA66 content increased. The nonisothermal crystallization kinetics of the PA56/PA66 co-PAs were analyzed using both the Avrami equation modifications presented by Jeziorny and Mo. The results also indicated that the crystallization rate of the PA56/PA66 co-PAs was higher than that of PA56.

Solid-Liquid Equilibrium Study for Binary System Forming Intermolecular Compound: Phase Diagram, Thermal, Physicochemical and Powder XRD study

The phase diagram study of the binary organic system has been investigated by the thaw melt method using 4-hydroxy- 3 methoxybenzaldehyde (HMB) and 4-nitroaniline (NA). The temperature-composition plot showed that the intermolecular compound (IMC) has formed at 1:1 molar ratio with two eutectics on either side of IMC. The melting points of eutectics and IMC along with parents are verified by the DSC method. The different phases of the systems which are in equilibrium and their physicochemical properties are estimated using the enthalpy of fusion values obtained from DSC. The higher melting temperature of IMC suggested the formation of Schiff base during homogenization process. The new and moderately sharp Bragg’s peaks at specific 2θ values found in the diffractogram of IMC revealed the novelty and crystalline nature of IMC while repeated peaks in the diffractogram of eutectics suggest the mechanical mixture of eutectics

Impact of the Dicarboxylic Acid Chain Length on Intermolecular Interactions with Lidocaine

Acid–base multicomponent systems have become a popular choice as a strategy to fine-tune the physicochemical properties of active pharmaceutical ingredients. Current prediction tools based on the principles of anticrystal engineering cannot always accurately predict the nature of intermolecular interactions within a multicomponent system. Even small changes in the physicochemical parameters of parent components can result in unexpected outcomes, and many salt, cocrystal, and ionic liquid forms are still being discovered empirically. In this work, we aimed to establish structural consistency in a series of mixtures comprising lidocaine (LID) with decanedioic, undecanedioic, dodecanedioic, and tridecanedioic acids and to explore how length and flexibility of the acid carbon backbone affect the molecular recognition, crystallization, and thermal behavior of the expected binary systems. We found that neat grinding of LID with dicarboxylic acids results in the formation of eutectic phases. The observed eutectic melting points deviated from the ideal eutectic temperatures predicted by the Schroeder van Laar model because of hydrogen bonding between the reacting components within the mixtures. Furthermore, thermal and infrared analysis provided evidence for the possible formation of new phases stemming from partial ionization of the counterions. Besides, the structure of a previously undetermined form I of the tridecanedioic acid was solved by single crystal X-ray diffraction.

Betaine-based deep eutectic solvents mediated synthesis of zinc oxide nanoparticles at low temperature

Deep eutectic solvents (DES) are gaining popularity as a potential substitute for ionic liquids because of their lower cost and biodegradability. Betaine and phenol with melting points ∼300 °C and ∼43 °C, respectively, combine with a molar ratio of 1:2 to form a liquid at room temperature with a eutectic melting point of ∼20 °C. ZnO nanoparticles (NPs) were synthesized by using an eco-friendly and green synthesis method utilizing betaine-based DES at low temperature ∼80 °C for 2 h. X-ray diffraction analysis confirms the highly crystalline and single-phase formation of ZnO NPs with hexagonal-Wurtzite phase structure. The surface morphology of the ZnO NPs confirmed using scanning electron microscopic images revealing the mostly spherical in shape and some n-pointed stars and transmission electron microscopy images confirms that NPs are sub-100 nm in range. Also, energy dispersive X-ray results confirm the elemental composition of Zn K (∼8.6 keV) and O K (0.52 keV) to be ∼88.5 ± 1.7% and 11.5 ± 1.3%, respectively. Fourier transform infrared spectroscopy confirms the bands at 565 and 410 cm−1 is assigned to asymmetric stretching and bending vibrations of the Zn–O tetrahedron. Thermogravimetric analysis verified the thermal stability with phase purity, resulting in the formation of the single-phase crystalline ZnO NPs. UV–Vis absorption study confirms the bandgap of ∼3.1 eV. The high stability and dispersion of NPs in water confirms the interaction of DES molecules on the surface of the NPs with water. ZnO NPs incorporated in PVA thin films show strong UV–Vis absorption confirming use of these transparent thin films for UV-shielding applications. As far as we know, this study is unique, green, eco-friendly and cost-effective in that the authors were able to synthesize ZnO NPs from betaine-based DES.

High-resolution investigation by Peltier-element-based adiabatic scanning calorimetry of binary liquid crystal mixtures with enhanced nematic ranges

High-resolution Peltier-element-based adiabatic scanning calorimetry (pASC) has been used to investigate the temperature dependence of the specific heat capacity and specific enthalpy of two mixture systems of the liquid crystal smectic A1 compound 5-n-nonyl-2-(4′-isothiocyanatophenyl)dioxane-1.3 (9DBT), and one of the smectic Ad compounds 4-n-octyloxy-4′-cyanobiphenyl (8OCB) and 4-nonyloxy-4′cyanobiphenyl (9OCB). For both mixture systems, measurements have been carried out over a large temperature range, from the crystalline solid phase over the smectic and nematic phases into the isotropic liquid phase. Both systems exhibit substantial, mixing-induced, enhanced nematic ranges and large changes in the composition dependence of the transition temperatures between the different phases. In both systems, eutectic melting points have been located and, for the different mixtures, the melting and eutectic transition heats have been obtained. The nematic to isotropic (NI) transitions are weakly first order with latent heat values in the range usually observed for this transition in other liquid crystals. The critical behavior of the specific heat capacity at the NI transition is described by exponent values near the tricritical one of 0.5. Along the smectic A to nematic (AN) transition lines, strong composition dependence was observed for the latent heat, from almost zero to values comparable to those observed at the nematic to isotropic transition. The concentration dependence of these AN latent heats was adequately fitted with a crossover function consistent with a mean-field free-energy expression that has a nonzero cubic term; the latter is induced by the Halperin-Lubensky-Ma coupling between the smectic A order parameter and orientational order director fluctuations. The fitting analysis resulted in the location of a Landau-tricritical point along one branch of the transition line in the system 9DBT-8OCB and one in each branch (for low and high 9OCB mole fractions) of the NA transition line of the 9DBT-9OCB system. The effective critical exponent values for the specific heat capacity of the AN transitions follow the McMillan ratio-dependence observed for other liquid crystal mixtures.

Community College Ceramics and Student Research: Cooperative Work Experience Projects in the Arts

For the past three semesters in the Fine Arts Program at Allan Hancock College, student researchers have been sampling, researching, and firing natural clay deposits found in the campus region. Students research local clays by firing them at various temperatures and adding variable fluxes to experiment with eutectic melting points. A cooperative work experience project is being piloted to develop a model outreach/interdisciplinary curricular guide for the Minerals Resources Program.