Eutectic Research Articles

High-Pressure Density of Eutectic Mixtures Containing dl-Menthol and Acetic Acid

High-Pressure Density of Eutectic Mixtures Containing dl-Menthol and Acetic Acid

Ultrasensitive Ratiometric Fluorescent Nanothermometer with Reverse Signal Changes for Intracellular Temperature Mapping.

Sensing temperature at the subcellular level is pivotal for gaining essential thermal insights into diverse biological processes. However, achieving sensitive and accurate sensing of the intracellular temperature remains a challenge. Herein, we develop a ratiometric organic fluorescent nanothermometer with reverse signal changes for the ultrasensitive mapping of intracellular temperature. The nanothermometer is fabricated from a binary mixture of saturated fatty acids with a noneutectic composition, a red-emissive aggregation-caused quenching luminogen, and a green-emissive aggregation-induced emission luminogen using a modified nanoprecipitation method. Different from the eutectic mixture with a single phase-transition point, the noneutectic mixture possesses two solid-liquid phase transitions, which not only allows for reversible regulation of the aggregation states of the encapsulated luminogens but also effectively broadens the temperature sensing range (25-48 °C) across the physiological temperature range. Remarkably, the nanothermometer exhibits reverse and sensitive signal changes, demonstrating maximum relative thermal sensitivities of up to 63.66% °C-1 in aqueous systems and 44.01% °C-1 in the intracellular environment, respectively. Taking advantage of these outstanding thermometric performances, the nanothermometer is further employed to intracellularly monitor minute temperature variations upon chemical stimulation. This study provides a powerful tool for the exploration of dynamic cellular thermal activities, holding great promise in unveiling intricate physiological processes.

Structures in grain-refined directionally solidified hypoeutectic Al-Cu alloys: Benchmark experiments under microgravity on-board the International Space Station

Benchmark solidification experiments were successfully performed under microgravity conditions on-board the International Space Station (ISS) within the ESAprogramme CETSOL (Columnar-to-Equiaxed Transition in SOLidification Processing). Cylindrical samples of grain-refined Al-4wt.%Cu, Al-10wt.%Cu and Al-20wt.%Cu alloys were directionally solidified in a gradient furnace to investigate columnar and equiaxed dendritic growth structures as well as the columnar to equiaxed transition under diffusive conditions. The determination of temperature gradients; interface velocities; and cooling rates at liquidus, solidus, and eutectic front positions provides well-defined thermal experimental characterization. The evaluation of the flight samples demonstrates that no significant macrosegregation along the sample axis occurred and no radial effects were observed. Therefore, purely diffusive solidification behaviour without any residual melt convection can be assumed for these microgravity experiments. The analyses of the microstructure in longitudinal cross-sections show dendritic structures without any pore formation and the averaged eutectic fraction is largely constant along the sample. The samples of refined Al-4wt.%Cu alloy show a sharp CET from columnar dendrites to a fine equiaxed steady-state grain structure whereas in the samples of refined Al-10wt.%Cu and Al-20wt.%Cu alloy, only equiaxed dendritic grain growth is observed. A quantitative analysis of the equiaxed grain morphology shows, that the shapes of the equiaxed dendrites depend on the applied temperature gradient, but the grain sizes in radial and longitudinal directions are identical. Therefore, a fully equiaxed dendritic growth structure without dendrite elongation was obtained. Compared to experiments in microgravity with non-refined Al-Cu alloys the average equiaxed grain size is about three times smaller.

Green Chemistry Approach To Improve Physicochemical Properties Of Glimepiride Through Eutectic Mixture Formation

Glimepiride (GL) is an oral hypoglycaemic agent with compromised solubility. The present work is intended to improve the solubility of this drug by formation of binary eutectic mixtures.

Design of Thermosensitive Niosomes by Eutectic Mixture of Natural Fatty Acids.

In the current study, a smart release system responsive to temperature was developed to improve the efficiency of tetracycline (TC) in antibacterial therapy. The nanovesicles designed consist of a non-ionic surfactant, SPAN60, cholesterol and a phase change material (PCM) as a thermoresponsive gating material. Niosomes were prepared using an increasing amount of PCM and characterized in terms of size, zeta potential, colloidal stability and thermoresponsive properties. The vesicles that developed were homogenous in size, had good biocompatibility and stability for up to 3 months and demonstrated thermoresponsive behavior. A low drug leakage was observed at 37 °C, while a rapid release occurred at 42 °C, due to the faster diffusion rate of the drug trough the melted PCM. This controllable drug release capacity allows us to avoid premature drug release, minimizing unwanted and toxic effects and ensuring a long retention time in the nanodevice so that it reaches the infected sites. In addition, TC-loaded niosomes were screened to investigate their antibacterial activity against various Gram-positive and Gram-negative bacteria by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays. An interesting temperature-dependent antibacterial activity was observed against some bacterial strains: the niosomes activity against S. epidermis, for example, was improved by the temperature increase, as suggested by a reduction in MIC values from 112.81 to 14.10 μM observed at 37 and 42 °C, respectively. Taken together, the thermoresponsive platform developed allows us to use lower antibiotic amounts while ensuring therapeutic efficacy and, so, will advance the development of a novel antibacterial agent in clinical practice.

Innovative dodecane-hexadecane/expanded graphite composite phase change material for sub-zero cold storage applications

Utilization of phase change materials (PCMs) for cold energy storage has garnered increasing attention. This study focuses on the development of a composite PCM by integrating a novel eutectic dodecane-hexadecane (DD-HD) PCM into expanded graphite (EG), to cater to the demands of sub-zero cold energy storage applications, such as cold chain logistics. The study identified the optimal mass ratio of DD-HD as 80:20. A series of DD-HD/EG composites were fabricated through a combination of high-speed emulsification and physical adsorption methods. The adsorption capacity of EG for the eutectic PCM mixture was evaluated by examining the impact of EG fraction on the leakage of the composite PCM, revealing that the optimum EG fraction is 10 wt%. The composite PCM displayed a sub-zero phase change temperature of -12.09 ℃, a high melting enthalpy of 178.75 kJ/kg, and a high thermal conductivity of 5.18 W/(m•K). The thermal conductivity of the composite was enhanced by 22.52 times compared to the base PCM. Thermogravimetric analysis indicated that the decomposition temperature of DD-HD/EG was significantly higher than that of the base PCM. The composite demonstrated outstanding thermal reliability, as evidenced by thermal cycle tests. With its impressive thermal characteristics, this composite shows great potential for various cold energy storage applications.

Efficacy of EMLA for Office-based Andrology Procedures Under Local Anesthesia: A Randomized Control Trial

ObjectiveTo evaluate the effectiveness of Eutectic Mixture of Local Anesthetic (EMLA), a topical anesthetic cream, in office-based invasive andrological procedures such as hydrocelectomy, spermatocelectomy, and others, aimed at minimizing pain perception and enhancing the overall patient experience. MethodsA double-blinded randomized controlled trial was conducted for patients undergoing scrotal andrology surgeries under LA. Power calculation was performed with an estimated sample size of 72. Participants were randomly assigned in a 1:1 ratio to topical EMLA + LA vs LA alone. In the post-operative recovery area, patient will be asked to complete a VAS questionnaire rating pain with LA administration and pain with procedure. Analysis comparing VAS pain scores of both groups was performed using the independent sample t-test method. Results72 patients were included in our analysis, with 36 in the control and 36 in the intervention arm. For patient pain with administration of LA, the control arm reported an average VAS pain score of 4.31, compared to 3.72 in the intervention arm (p=0.319). For patient pain with procedure, patients in the control arm reported a median VAS pain score of 3.47 compared to 3.03 (p=0.432) in the intervention arm. Overall, 86% (62/72) of patients reported that they would either be “very likely” (4/5) or “highly likely” (5/5) to undergo future procedures under local anesthetic. ConclusionsWhile performing scrotal surgeries under LA appears to be well tolerated and a feasible option, the application of EMLA cream does not appear to significantly alter patient-reported outcomes.

Evolution of cracks in laser powder bed fused AA2024 and its processing parameter dependence

Hot cracking is one of the most hideous issues in the fabrication of high-strength aluminum alloys via laser powder bed fusion (LPBF). This study investigated the evolution of hot cracking in LPBFed AA2024 and explored its processing parameter dependence. Results showed that most cracks distribute along continuous eutectic phases residing at grain boundaries. At the last stage of solidification, the eutectic composition with low melting point exists as a liquid film, which can be easily ruptured under stress caused by thermal contraction. This leads to the formation of cracks along grain boundaries. This cracking process is also related to the misorientation angle of grains, where higher angle results in more stable liquid films. Furthermore, increasing the laser power transforms the grain structure from fine columnar grains to coarse columnar grains, which eventually transform to a mixture of columnar and equiaxed grains. This grain structure transition results in the decrease followed by increase of critical stress for the rupture of liquid film. On the other hand, decreasing the scanning speed increases the eutectic phase content, which could enhance the permeability of mushy zone and thus reduce the cracking susceptibility. These findings could provide guidance for the fabrication of crack-free high-strength aluminum alloys via LPBF.

Improving laser powder bed fusion processability of pure Cu through powder functionalization with Ag

The Laser Powder Bed Fusion (LPBF) manufacturing of dense Cu parts with near infrared conventional systems is still challenging due to the high reflectivity and thermal conductivity of the powder. In this paper, we investigate a novel approach to improve LPBF processability of Cu through the modification of particle surface properties. Pure Cu powders were coated with a thin layer of high-conductivity Ag by electrodeposition. The coated powder was also heat-treated at 500 °C and 600 °C to promote diffusion at the coating interface, producing different powder particle configurations. LPBF equipped with 200 W laser was used to produce bulk samples using pure Cu and Cu/Ag powder, which were comprehensively characterized by electron microscopy and X-ray diffraction. The Ag coating improved the material processability and density, forming a eutectic phase mixture able to heal pores and defects at the end of the solidification process.

Influence of anodic treatment of nickel in deep eutectic solvents on electrocatalytic activity in oxygen evolution and urea oxidation reactions

The influence of anodic potentiostatic treatment of nickel surface in deep eutectic solvents, ethaline and reline (eutectic mixtures of choline chloride with ethylene glycol and urea, respectively), on the electrocatalytic activity in the electrochemical reactions of oxygen evolution and urea oxidation in an aqueous alkaline medium (1 M NaOH) was investigated for the first time. It was shown that, depending on the chosen treatment potential and the nature of the eutectic solvent used, a significant increase in the rate of the studied processes was observed. Specifically, after anodic treatment of nickel under certain conditions, the polarization of the oxygen evolution reaction at a current density of 0.1 A/cm2 could be reduced by approximately 150–200 mV, and the maximum current density of urea oxidation could be increased by an order of magnitude (from 0.012 A/cm2 to 0.131 A/cm2 at a urea concentration of 0.33 mol/dm3 in alkaline solution). The observed increase in electrocatalytic activity after anodic treatment of nickel in deep eutectic solvents is likely related to changes in surface morphology patterns and the nature and concentration of relevant electroactive sites on the electrode surface. The results obtained in this work can be used for the development of highly efficient electrode materials for green hydrogen energy.

Nonoperating room regional anesthesia in pediatric patients: A review of indications and challenges

Nonoperating room regional anesthesia (NORRA) involves providing regional anesthesia in environments other than the standard operating rooms, such as in intensive care units, emergency departments, or interventional radiology suites. Although regional anesthesia is well-documented for its benefits in perioperative care, its application in nonoperating room environments remains limited. We conducted a narrative literature review using various databases such as PubMed, Embase, Medline, Ovid, PMC, and Google Scholar. Our search strategy involved using different combinations of terms associated with regional anesthesia, nonoperating room anesthesia, intensive care units, and pediatric patients. Regional anesthesia offers significant benefits for pediatric patients, such as reducing the need for opioids and enhancing autonomic, metabolic, and immunological responses. Techniques used in NORRA include central neuraxial blocks, peripheral nerve blocks, and topical anesthesia, with common anesthetic agents being lidocaine, bupivacaine, and eutectic mixture of local anesthetic cream. This review investigates the applications, indications, challenges, and future prospects of NORRA in pediatric patients.

Comparing the Efficacy of 5% EMLA Cream and 20% Benzocaine Gel on Gingival Tissue Surrounding Non-Carious Cervical Lesions for Reduction of Pain Following Rubber Dam Clamp Placement: A Split-Mouth Randomized Clinical Trial.

Aim The aim of this study was to evaluate the effectiveness of 5% eutectic mixture of local anesthetics (EMLA) cream and 20% benzocaine gel in reduction of pain during rubber dam clamp placement in the treatment of non-carious cervical lesions (NCCLs). Methodology In this split-mouth single-blind randomized clinical trial, 50 adult participants were selected from the outpatient department. The test group was treated using 5% EMLA cream for three minutes, and visual analog scale (VAS) scores were recorded. The comparison group was treated using 20% benzocaine gel and procedure was repeated as that in the test group. After recording the VAS scores, NCCLs in both the groups were restored using composite restoration. Results In the included 50 participants, 70% were males, with an age group of 31-67 years. The mean VAS score at 3 minutes in EMLA group was significantly lower than that in benzocaine group. Conclusion Application of 5% EMLA cream for 3 minutes showed greater pain reduction during rubber dam clamp placement as compared to 20% benzocaine gel in adult patients with NCCLs.

Influence of anodic treatment of a copper-nickel alloy in a eutectic mixture of choline chloride and urea on the surface morphology and electrocatalytic behavior in the hydrogen evolution reaction

For the first time, we investigated the process of potentiostatic anodic treatment of the surface of a copper (≈55%)-nickel alloy in a eutectic mixture of urea and choline chloride (reline), which is a typical representative of a new generation of ionic liquids, deep eutectic solvents. The anodic behavior of the alloy in the used solvent was characterized by cyclic voltammetry, and the nature of the electrochemical dissolution reactions of individual components of the alloy corresponding to several anodic current waves registered in voltammograms was determined. It was established that the anodic dissolution of the alloy occurs under conditions of salt surface passivation due to the formation of a layer of poorly soluble products of the electrode reaction. It was shown that under conditions of prolonged (150 min) potentiostatic polarization of the alloy in reline for various values of the electrode potential (in the range from 0.1 to 1.7 V relative to the Ag reference electrode), the chemical composition of the surface remained unchanged (i.e., there was no selective etching of individual components of the alloy), but an evolution of surface morphology patterns was observed, the specific type of which depended on the value of the applied potential. Anodic treatment of the Cu-Ni alloy in the reline solvent at any of the investigated anodic potentials led to an increase in the surface roughness coefficient, and electrochemical polishing did not occur. Analysis of kinetic data related to the hydrogen evolution reaction on the surfaces of reline-treated copper-nickel alloys in a 1 M NaOH aqueous solution showed a significant increase in exchange current density. This indicates enhancement of electrocatalytic activity compared to the untreated surface. The observed effect is likely associated with an increase in the true surface area of the alloy available for electrochemical reaction and an increase in the surface concentration of electrocatalytic sites resulting from the anodic dissolution of the alloy. The obtained results can be used in the development of highly efficient and relatively inexpensive electrocatalysts for hydrogen energy.

Electrodeposition of dendrite-free Zn on Au from deep eutectic system based on choline chloride

Electrodeposition of dendrite-free Zn on Au from deep eutectic system based on choline chloride

Thermodynamic Analysis of Chloride Corrosion in Steel for Energy System Applications in Fe-O-Cl-Na Environments

The assumptions of contemporary energy policies are increasing the share of renewable energy sources. Biomass combustion is developing as an alternative to fossil fuels. However, it faces challenges such as limited corrosion resistance of steel boiler components due to chloride compounds in flue gases and fly ash. This paper provides a comprehensive thermodynamic analysis of chloride-induced corrosion in steel in the Fe-O-Cl-Na environment, focusing on the influence of steam concentration in the gas phase. The study was performed by using the general thermodynamic rules, the thermodynamic properties of the pure components involved in the reaction, and the properties of the solutions formed in the liquid and gas phases. The study also examined the impact of alkali metal chlorides, particularly NaCl, on the formation of NaFeO2 in the passive oxide scale layer Fe3O4/Fe2O3. Furthermore, it investigated the condensation of NaCl vapour formation of low-melting eutectic mixtures in deposits and the resulting consequences on the corrosion process. The role of HCl in the chlorination and oxidation process of steel in melted ash deposits was also discussed. The presented thermodynamic analysis was compared with assumptions of an “active oxidation” model. This study can be a valuable resource for experimental research planning and a guide for preventing corrosion in industrial settings.

Thermo-activated in situ rectal gel preparation for Ibuprofen using eutectic mixture.

This study aimed to develop a thermosensitive in situ gel formulation for rectal delivery of Ibuprofen as an efficient alternative dosage form. Utilizing poloxamer 188, poloxamer 407, and HPMC via cold technique method, a thermosensitive in situ gel was successfully prepared. The concentration of Ibuprofen in the formulations was 1.2 % (w/w). The prepared gels underwent assessment for clarity, gelation temperature, gelation time, gel strength, spread ability, syringe-ability, pH, viscosity, FTIR, and drug content. The selected formulations exhibited a gelation temperature within the range of 30 °C to 36 °C, with consistent amount of drug soluble in the formulations (93 % - 110 %). Mucoadhesive studies, in vitro release tests, ex vivo modeling of drug release, kinetic studies modeling, and histopathology testing were also conducted. The formulation comprising 18 % poloxamer 407, 12 % poloxamer 188, and 1 % sodium chloride (FS15) demonstrated suitable gelation temperature and desirable drug release rate. In vitro drug release tests indicated completion within one hour for both FS10 (20 % P407 & 10 % P188) and FS15 (18 % P407 & 12 % P188), with consistent and predictable release patterns observed through kinetic modeling analysis. Microscopic histopathology examination confirmed the safety of the selected formula, exhibiting no irritation in the mucosal membrane of the sheep. In conclusion, Ibuprofen thermosensitive in situ gel presents a promising and convenient strategy as a rectal carrier and an alternative dosage form to solid suppositories.

Friction behavior and wear mechanism of laser cladded FeNiCr-WC composite coatings in comparison with different friction pairs

Complex formation structures lead to significant differences in the failure mechanisms of hobs. WC-reinforced medium entropy composite coatings exhibit excellent comprehensive properties. However, the wear mechanism of coatings in different formation structures is still unclear. In this study, FeNiCr-WCx (x = 0, 40, 50, 60 wt%) composite coatings were prepared on the surface of H13 steel using laser cladding technology. The friction and wear mechanism of FeNiCr-WC composite coatings under different friction pair conditions was discussed. The results show that FeNiCr-WC composite coatings mainly consist of reinforced phase, lamellar eutectic structure and solid solution phase. As the WC content increases, the content of M6C and carbide phases in these coatings increases. The average microhardness of 40WC, 50WC and 60WC coatings is 3.28 times, 3.61 times and 4.20 times that of H13 steel, respectively. The wear rates of 40WC, 50WC and 60WC coatings are respectively about 0.25, 0.10 and 0.06 times that of FeNiCr coating under Al2O3 friction pair conditions. Three-body wear and oxidation wear mainly occurred on the surface of FeNiCr-WC composite coatings. The wear rates of 40WC, 50WC and 60WC coatings are respectively about 0.34, 0.35 and 0.16 times that of FeNiCr coating under Si3N4 friction pair conditions. Glaze layers with high Si content were formed on the surface of 50WC and 60WC coatings. The glaze layer is prone to cracking and peeling, resulting in increased wear rates for both coatings. As the hardness of the coating increases, the GCr15 friction pair undergoes severe abrasive wear.

The new phthalic acid-based deep eutectic solvent as a versatile catalyst for the synthesis of pyrimido[4,5-d]pyrimidines and pyrano[3,2-c]chromenes

A new DES (MTPPBr-PHTH-DES) was prepared from a mixture of methyltriphenyl-phosphonium bromide (MTPPBr) and phthalic acid (PHTH). The eutectic point phase diagram showed that a one-to-one molar ratio of MTPPBr to PHTH is the optimal molar ratio for the synthesis of new DES. Then, it was characterized with various techniques such as FT-IR, TGA/DTA, densitometer, eutectic point, and NMR and used as a novel acid catalyst in the synthesis of pyrimido[4,5-d]pyrimidines and pyrano[3,2-c]chromes in solvent-free condition. Short reaction time, low temperature, high efficiency, green condition, and easy recycling and separation of the DES catalyst are among the most important features of the presented method.

Enhanced strength and ductility in a brittle hypoeutectic high-entropy alloy via spheroidizing annealing

Eutectic high-entropy alloys (EHEAs), combining the advantages of traditional eutectic alloys and high-entropy alloys (HEAs), have become a promising multi-principal alloy system for industrial application. Further improving the strength-ductility of EHEAs has been the pursuit of researchers. In this work, we found that the strength and ductility can be improved simultaneously in a new class EHEAs with serrated eutectic structure via simple spheroidizing annealing. As a manifestation of this fascinating discovery, an Al0.25CoCrFeNi2V0.8B0.4 EHEA was developed that was composed of face-centered cubic (FCC) and serrated boride phase and then subjected to spheroidizing annealing. The ultimate tensile strength (UTS) and elongation (EL) increased from 1193 MPa, 4.3 % (in as-cast) to 1410 MPa, 15.7 % after spheroidizing annealing. This combined increase in strength and ductility was attributed to that the serrated boride eutectic phase is spheroidized into a dispersed spherical eutectic phase, which effectively alleviates the stress concentration and provides more space for dislocation slip, promoting strain-hardening ability during deformation. This work provides valuable insight into the development of high-performance EHEAs.

Investigation of scale formation and degeneration of silicide coating on Nb–Si based alloy in the temperature range from 1250 °C to 1560 °C

Nb silicide coatings modified with active elements have good oxidation resistance, but there is a lack of systematic research on their oxidation behavior at high temperatures above 1250 °C. The aim of this work is to investigate the oxidation behavior of an Al–Y modified silicide coating on Nb–Si based alloy in the temperature range from 1250 °C to 1560 °C. After oxidation at 1250 °C, the scale displays a typical layered structure consisting mainly of a TiO2 outer layer, an amorphous SiO2 matrix layer embedded with TiO2 and ZrSiO4, and an inner layer consisting of SiO2 and Cr2O3. Above 1350 °C, the evaporation reaction of Cr2O3 into CrO3 (g) is significantly accelerated and Cr2O3 disappeared gradually with temperature or time. The TiO2 layers covering on the scales formed at 1250–1500 °C grow along the crystallographic orientation of [100]. The micropores formed on the surface of TiO2 should be attributed to the further oxidation of Cr2O3 into volatile oxide CrO3 (g). The scales exhibit a similar structure consisting mainly of a SiO2 glass matrix embedded with ZrSiO4 and a surface TiO2 layer until 1500 °C. Above the eutectic temperature of SiO2–TiO2 system, the scale is mainly composed of a matrix layer of SiO2–TiO2 eutectic embedded with block TiO2 particles, and a thin SiO2 interface layer at 1560 °C. The degeneration path of the (Nb,X)Si2 coating is (Nb,X)Si2 → (Ti,Nb)5Si4 → γ-(Nb,X)5Si3.