Eutectic Research Articles

Corrosion effects of Na2CO3/NaCl molten salt eutectic on 316L stainless steel under isothermal and cycling conditions

Using phase-change materials in thermal energy storage systems for concentrating solar thermal plants can significantly reduce the volume of storage media and, therefore, the cost of the system. However, this approach introduces new material compatibility issues between the thermal energy storage material and the containment vessel in the form of corrosion and thermal transients, which are inherent in these systems. Rods and sheet coupons of stainless steel 316L were corroded for up to 768 h in 59.4/40.6 wt% Na2CO3/NaCl eutectic salt under isothermal (650 °C) and cycled conditions (between 600 and 650 °C). The testing methodologies correspond to actual service conditions, as isothermal degradation may not represent material loss under typical solar thermal cycling conditions. Mass losses were calculated via the Dynamic Gravimetric Analysis technique while Scanning Electron Microscopy utilizing Energy Dispersive Spectroscopy was used to analyze the corrosion layers. Isothermal mass loss plateaued at 75 mg/cm2 at 96 h with no further measurable loss after this time, while cycled samples had a fast initial mass loss rate of 60 mg/cm2 in the first 96 h and lost 0.0331 mg/cm2 every hour thereafter. The results indicate that isothermal samples corrode more slowly than the predominant industry cases of thermal cycling. Spalling is responsible for the degradation in both sets; the continual temperature changes in the cycled samples lead to additional stresses, exacerbating the effect.

A self‐regulated phototheranostic nanosystem with single wavelength‐triggered energy switching and oxygen supply for multimodal synergistic therapy of bacterial biofilm infections

AbstractThe exploration of antibiotic‐independent phototherapy strategies for the treatment of bacterial biofilm infections has gained significant attention. However, efficient eradication of bacterial biofilms remains a challenge. Herein, a self‐regulated phototheranostic nanosystem with single wavelength‐triggered photothermal therapy (PTT)/photodynamic therapy (PDT) transformation and oxygen supply for multimodal synergistic therapy of bacterial biofilm infections is presented. This approach combines a eutectic mixture of natural phase‐change materials (PCMs) and an aggregation‐induced emission (AIE) phototheranostic agent TPA‐ICN to form colloidally stable nanopartcicles (i.e. AIE@PCM NPs). The reversible solid−liquid phase transition of PCMs facilitates the adaptive regulation of the aggregation states of TPA‐ICN, enabling a switch between the energy dissipation pathways for enhanced PDT in solid PCMs or enhanced PTT in liquid PCMs. Additionally, oxygen‐carrying thermoresponsive nanoparticles are also introduced to alleviate the hypoxic microenvironment of biofilms by releasing oxygen upon heating by AIE@PCM NPs with enhanced PTT. The nanosystem exhibits outstanding therapeutic efficacy against bacterial biofilms both in vitro and in vivo, with an antibacterial efficiency of 99.99%. This study utilizes a self‐regulated theranostic nanoplatform with adaptive PTT/PDT transformation via the phase transition of PCMs and heat‐triggered oxygen release, holding great promise in the safe and efficient treatment of bacterial biofilm infections.

Development and preparation of novel nano-enhanced organic eutectic phase change materials for low-temperature solar thermal applications

ABSTRACT Thermally reliable and stable eco-friendly Phase change materials are of significant aid in thermal energy storage technology, leading to improved energy utilization and reliability of the system. This study develops two novel organic eutectic PCM of Lauric acid – Margaric acid (LM) and Myristic acid – Margaric acid (MM), which are chemically stable and thermally compatible for latent heat energy storage. LM eutectic mixture had a melting temperature of 52.66°C with a latent heat of 163.68 J/g, and MM eutectic mixture had its melting temperature at 44.79°C and a latent heat of 197.31 J/g. The phase change temperatures were favorable for low temperature solar thermal applications with good latent heat capacity. The thermal characteristics of these eutectic mixtures are further enhanced with the dispersion of highly conductive Multi walled carbon nanotubes (MWCNT) at three different mass fractions (.5%, 1% and 1.5% by weight). Nano enhancement could achieve exceptional thermal conductivity enhancement in MM eutectic mixture by 110.6% and 83.73% in LM eutectic mixture. Thermogravimetric analysis and Fourier-transform infrared spectroscopy analysis ensured the thermal and chemical stability of the eutectic mixtures. The optical absorption characteristics were extensively enhanced with nano particle addition, which is highly preferable in solar thermal applications.

Choline chloride-L-lactic acid mixtures as solvents for extraction of Coumarin from cinnamon-containing foods

The determination of coumarin in generally available cinnamon-containing foods such as biscuits, cereals is important to ensure that the populations consuming these foods more frequently are not exposed to higher levels and are not at risk. This study describes the development of an analytical method for determination of coumarin in foods containing cinnamon. Solid-liquid phase extraction with conventional stirring-assisted and ultrasound-assisted extraction (UAE) procedures were used to prepare sample extracts for liquid chromatography analysis. The green solvent, a mixture of choline chloride:L-lactic acid (1:4, mol/mol)/water (50:50 v/v), as a deep eutectic solvent-like mixture, was selected as an extraction solvent. The extraction conditions were optimized by using the design of the experiment strategy obtaining parameters, temperature 47 °C, time 36 min, solvent volume 4 mL, sample amount 0.8 g, stirring speed 20 rpm for rotary stirring-assisted extraction procedure, and temperature 30 °C, time 5 min, solvent volume 3.5 mL, sample amount 0.8 g for UAE. High-performance liquid chromatography separation with a total analysis time of 12 min was performed with a stationary phase of octadecyl type and a gradient of mobile phase of methanol-1 % acetic acid. The methods were successfully validated to show the detection limit of 0.13 μg.mL−1, the linearity range of 0.4–50 µg.mL−1 (R2 = 0.999), recovery values more than 80 %, and the RSDs of less than 7 %. Rotary stirring-assisted extraction showed moderately higher recovery values than UAE, while lower RSD % was observed for UAE.

Development and reliability assessment of nano-enhanced novel organic eutectic mixtures as phase change materials for latent heat energy storage

Development and reliability assessment of nano-enhanced novel organic eutectic mixtures as phase change materials for latent heat energy storage

On the properties of water in betaine – based Deep Eutectic Solvents

Deep eutectic solvents have gained attention as environmentally friendly alternatives in various technological applications. Likewise, it is known the relevant effect of water on the physicochemical properties of Deep Eutectics, especially for hydrophilic ones. In this study, Betaine – based type III Deep Eutectic solvents (with ethylene glycol, fructose, malic acid or citric acid as Hydrogen Bond Donors) are considered and the properties and structuring of water in Deep Eutectic solutions (content lower than 20 %) were investigated considering volumetric properties, optical properties (refraction index), dynamic properties (viscosity, thermal conductivity, and electrical conductivity) as well as relevant characteristics for liquid phase nature such as polarizability and molecular packing. Viscosity measurements demonstrated a wide variation in viscosities, with water content playing a significant role, thus probing how water content largely affect dynamic properties of Deep Eutectics. Additionally, high water content led to improved thermal and electrical conductivity, particularly in mixtures containing citric acid and malic acid as Hydrogen Bond Donors. The polarizability decreased with increasing water content, and packing calculations indicated that the most voluminous molecules occupied interstitial voids. Our findings contribute to the understanding of water in Deep Eutectics solution, aiding their optimization for sustainable applications.

Comparison of 2% lidocaine infiltration and eutectic mixture of local anesthetics cream application before spinal needle insertion for pain reduction and assessment of maternal satisfaction levels in women undergoing cesarean section at a tertiary care se.

This study aimed to compare two analgesic pretreatment techniques for assessing pain reduction before spinal needle insertion and the subsequent patient satisfaction levels in pregnant female patients undergoing cesarean sections. Sixty pregnant female patients scheduled for elective cesarean section under spinal anesthesia were randomly assigned to two groups. The Lidocaine group received local skin infiltration with 2% lidocaine pretreatment before spinal needle introducer insertion, whereas the eutectic mixture of local anesthetics (EMLA) group received EMLA (lidocaine 2.5% and prilocaine 2.5%) cream pretreatment for at least 30 min before spinal needle introducer insertion. Subjective and objective pain scores, procedure duration, number of attempts, maternal satisfaction, and decisions regarding future numbing procedures and regional anesthesia were assessed. The demographic characteristics of the patients were similar between groups. The mean visual analogue scale pain score was significantly lower in the EMLA group compared to the lidocaine group (P < 0.05). Additionally, the objective pain score was significantly lower in the EMLA group (P < 0.05). The duration of spinal block placement was significantly longer in the lidocaine group than in the EMLA group (P < 0.05). The number of attempts to perform the spinal block placement was similar in both groups. However, women in the EMLA group expressed greater overall satisfaction than those in the lidocaine group (76.7% vs. 20.0%, P < 0.05). Analgesic pretreatment with EMLA cream is superior to local skin infiltration with lidocaine in pregnant patients undergoing elective cesarean section under spinal anesthesia.

Development of NiCrFeCoBX eutectic high entropy alloy coating by laser cladding: Investigation of microstructural, solidification, corrosion, and wear properties

Developing protective coatings resistant to corrosion and wear has always been a challenge in various industries. In this work, we processed NiCrFeCoBx (x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) high-entropy alloy by laser cladding on a GTD-111 superalloy. At B ≤ 0.3, the microstructure of the coating consisting of inter-dendritic FCC1 and FCC2 lamellae coupling was confirmed by XRD and SEM analysis. By increasing the value of B (B≥ 0.4), a coating with the phase structures of FCC1, FCC2, and MXBY was identified. The presence of Cr-rich borides (MXBY) was attributed to the enrichment of the eutectic composition with B and its segregation into interdendritic regions. With increasing B, more areas were created for inhomogeneous nucleation of dendrites from the melt, resulting in a finer eutectic structure with a higher volume fraction. The comparison between B0.1 and B0.6 samples showed that the hardness increased from 240 HV to 603 HV and the coefficient of friction decreased from 0.63 to 0.42. Raising the B value led to a drop in the corrosion current potential of the NiCrFeCoBX coating from −0.456 V to −0.895 V in a 3.5 % NaCl solution. Additionally, this shift altered the corrosion mechanism from pitting to intergranular corrosion. This was attributed to the high surface energy of the eutectic phase and the intensification of galvanic corrosion.

A Review on Transdermal Drug Delivery System (TDDS)

The transdermal route of administration has numerous advantages over more traditional routes of medicine administration. They contain high bioavailability, lack of first- pass hepatic metabolism, stable tubemedicineconcns., and the fact that the treatment is non-invasive. The biggest hedge to the penetration of medicinalmotes is the external subcaste of the skin, the stratum corneum. therefore, exploration to ameliorate transdermal medicine delivery( TDD) is worthwhile this subcaste is the area of interest. This review composition is written togive content commentary recent advances in TDDS enhancement ways. ways that ameliorate the permeability of the skin have been used developed to ameliorate bioavailability and increase the choice of topical and transdermal medicines is a feasible option. This review describes improvement ways grounded on medicine/ vehicle optimization, e.g selection of medicines, prodrugs and ion dyads, supersaturated medicine results, eutectic systems, complexes, liposomes, vesicles and patches. Strengthening by changing the shell with moisturizing chemical enhancers partitioning and solubility goods affecting crustal lipid and keratin structure bandied Medium of action of penetration enhancers and retarders and they're implicit for clinical use operation is described

Role of ionic liquids in ibuprofen-based eutectic systems: Aqueous solubility, permeability, human cytotoxicity, hemolytic activity and anti-inflammatory activity

Eutectic systems, as well as ionic liquids (ILs), offer a potential solution to the challenges associated with low solubility, polymorphism, and limited bioavailability of active pharmaceutical ingredients (APIs). Herein, we prepared twelve pharmaceutically active eutectics based on ibuprofen (Ibu), a widely accessible without prescription non-steroidal anti-inflammatory drug (NSAID), and imidazolium-based ILs ([C2C1Im]Cl, [C2(OH)C1Im]Cl and [C2C1Im][C1CO2]) and cholinium salt ([N1112(OH)]Cl) at different molar ratio (2:1, 1:1, 1:2 and 1:5). All eutectic systems were characterized by DSC and NMR, and their polarity was assessed using the Kamlet-Taft approach to characterize the non-specific (polarity/polarizability) and specific (hydrogen bonding ability) interactions. An upgrade of the aqueous solubility (water and biological simulated fluids) for the Ibu-based eutectics relatively to ibuprofen was verified. Also, the assessment of ionicity (viscosity, conductivity, and density) was attained, confirming the formation of ion-pairs or clusters, that increase the potential of these liquids to be more membrane diffusive. The biocompatibility of the Ibu-based eutectics was evaluated up to 3 mM (well above the ibuprofen maximum plasma concentration) through a hemolytic activity assay and in vitro cytotoxicity as-says with two human cell lines (Caco-2 colon carcinoma cells and HepG2 hepatocellular carcinoma cells), without impairing their hemolytic and cytotoxic response. Additionally, the anti-inflammatory activity was evaluated by the inhibition of bovine serum albumin (BSA) denaturation and inhibition of cyclooxygenases (COX-1 and COX-2) enzymes, showing that the ibuprofen eutectic formulations maintain the anti-inflammatory response of ibuprofen with the opportunity to improve the selectivity towards COX-2, allowing the development of safer NSAIDs.

Modification of steel slag to prepare chlorides based composite phase change materials with shape stability for high-temperature thermal energy storage

Using steel slag to prepare high-temperature (>500 °C) PCMs was an effective way to achieve its high value-added utilization as a potential heat storage medium in a variety of applications, such as solar energy storage, power peak shaving, and industrial waste heat recovery. However, the complex solid waste of steel slag might be corrosive to salt-based PCMs at high temperature. To address this issue, steel slag was firstly modified with another solid waste (i.e., CFA), which was then used to microencapsulate NaCl-KCl to prepare shape-stabilized C-PCMs in this work. Thermophysical and mechanical properties of C-PCMs were analyzed. Results showed that CFA modification greatly improved chemical compatibility between steel slag and eutectic salt through phase reconstruction. Steel slag modified with 30 wt% CFA at 1100 °C was identified as the optimum skeleton. The prepared C-PCMs containing 50 wt% salt showed a phase transition temperature of 653 °C with a high latent heat of 139 J/g and an excellent cycling stability. Additionally, its thermal conductivity reached 1.46 W/(m·K), 180 % higher than of pure salt. Compressive strength of the composite could be as high as 119 MPa, superior to other salt-based C-PCMs. A heat storage device was further designed to allow the numerical investigation of thermal performance of the prepared C-PCMs in practical conditions. Attributed by reasonable arrangement of bricks, the heat storage device possessed a uniform temperature distribution over the vertical cross-section of HTF, which contributed to a quick completion of charging and discharging process. This work could potentially lay a foundation for application of steel slag in the field of high-temperature thermal energy storage.

Thermophysical characterization and reliability analysis of binary composite nano doping on stearic acid-acetamide eutectic PCM

Organic phase change materials (PCM) have been extensively studied and employed for thermal energy storage applications, especially in the last decade. Wide range of melting temperature with high latent heat of fusion and absence of super cooling have made them highly desirable for energy storage applications, yet their intrinsic low thermal conductivity has been a major drawback in practical implementation. This study intends to address this and study the thermophysical characteristics of an organic PCM through composite nano doping. Stearic acid-acetamide eutectic PCM with a melting temperature of 65.73 °C and a latent heat of 203.72 J/g, was incorporated with a binary blend of Aluminum Oxide nanoparticles and multi-walled carbon nanotubes (MWCNT). The addition of metallic oxide and carbonaceous nanoparticles increased the melting temperature of the eutectic mixture by 2.9 °C and a highly advantageous increment in latent heat of fusion by 10% was observed, due to the improved molecular interaction introduced by the nanoparticles. Composite nano doping enhanced the thermal conductivity of the eutectic PCM by a 132.7% and also resulted in high optical absorption properties. The prepared eutectic mixtures were chemically stable and the eutectic PCM showed an improved final degradation temperature and thermal stability, with composite nano doping. Thermal reliability was analyzed through accelerated thermal cycling test and the eutectic mixtures could retain their thermal characteristics and chemical stability even after 500 thermal cycles. Composite nano doping proved to be a reliable thermophysical characteristics enhancement technique for organic eutectic PCM.

THERMOPHYSICAL PROPERTIES OF HYPOEUTECTIC, EUTECTIC AND HYPEREUTECTIC Al-Si AUTOMOTIVE ALLOYS UNDER AGEING TREATMENT

Influence of different levels of silicon under a variety of thermal treatment is investigated on the thermophysical behaviour of Al-Si-Cu-Mg automotive alloys. Conventional cast alloys are subjected to T6 heat treatment for age hardening. Hardness values, thermal conductivity along with microstructural observation under different heat-treated conditions are well thought-out to comprehend the ageing performance and the precipitation behaviour of the alloys. From these investigational results it is indicated that two successive hardening peaks take place in the agedalloys. Ageing sequence consists of different phases like a supersaturated solid solution, GP zones, intermediate βʹʹ, intermetallic βʹ, equilibrium β and the Q phase but GP zones and the metastable phases are most likely responsible for these ageing peaks. Thermal conductivity decreases for these precipitates formation during ageing and increases for relieving the internal stress, dissolution of metastable phase and coarsening the precipitation of the alloys. Addingup of Si to the alloy showed earlier ageing peaks with higher intensities intended for its increasing properties of heterogeneous nucleation and diffusion kinetics. After ageing around at 200°C for four hours the alloys offer the height hardness. Microstructural study reveals that eutectic silicon makes the grain boundary coarsen and beyond the eutectic composition the star-shaped blocky primary Si is formed. Subsequent to ageing at 350oC for one hour the alloys reach completely recrystallized state.

Synthesis of sulfide mineral crystals by incongruent methods using the example of Cu-Fe-S and Cu-Fe-Se systems

Research subject. Understanding the structure and thermodynamic properties of sulfide minerals is important for studying the paragenesis of sulfide formation on Earth and in space, as well as for analyzing technological issues in the processing of ores and polysulfide product concentrates. There is a lack of experimental and theoretical information on many representatives of the Cu-Fe-S and Cu-Fe-Se systems. Aim. To synthesize crystals in the Cu-Fe-S and Cu-Fe-Se systems at the lowest possible temperatures for the subsequent study of their physical properties, while solving the main problem of materials science related to interrelations between composition, structure, and properties. Materials and methods. Crystal synthesis was carried out by the solution-melt method in a stationary temperature gradient, in evacuated sealed quartz glass ampoules. Two types of ampoules were used in the experiment, standard and long. The ampoules were filled with a charge and a salt mixture of RbCl-LiCl of eutectic composition, evacuated and sealed, then placed in several quartz or ceramic glasses. The glasses were placed in tubular furnaces such that the ends of the ampoules with the charge were located closer to the center of the furnace, and the opposite ends were closer to the edge to create a temperature gradient. For standard ampoules, the hot end temperature was 520–469℃, and the cold end was 456–415℃. For long ones: 470℃ – hot end and 340℃ – cold. The synthesis duration ranged from three to four months. Results. Depending on the composition of the charge, crystals of chalcocine Cu2S, bornite Cu5FeS4, chalcopyrite CuFeS2, isocubanite CuFe2S3, and iron-containing dicopper sulfide with an iron content of up to 8 at % and various equilibrium associations with their participation and with the participation of pyrite FeS2 and pyrrhotites Fe1–xS were obtained. Copper dendrites were also found in some samples. In addition, crystals of a phase with the approximate composition of CuFeSe2 were obtained. It is shown that due to different combinations of oxidation states of all three elements dissolved in a salt electrolyte, it is possible to obtain phases with almost any stoichiometric ratio. Chalcopyrite and isocubanite are reliably detected using Raman spectroscopy. In this case, some samples are locally characterized by the “absence” of a spectrum, which probably indicates the metallic (semi-metallic) properties of the samples. Conclusion. Using the Cu-Fe-S and Cu-Fe-Se systems as an example, the possibility of obtaining sulfide crystals in a RbCl-LiCl salt melt up to a eutectic temperature of 313℃ is shown. Due to the low synthesis temperature, the synthesis should be carried out over several months, resulting in crystals a fraction of a millimeter in size.

Investigations on the Use of Deep Eutectic Solvents (DESs) as Promoters for the Conjugate Addition of α‐Nitroketones to Electron‐Poor Alkenes

AbstractDESs were profitably investigated as solvents and promoters of the conjugate reaction addition of cyclic and acyclic α‐nitroketones to a variety of electron‐poor alkenes. The best results were obtained conducing the reaction in betaine:1,2‐propanediol (1 : 5 molar ratio) DES at room temperature, and enones were demonstrated to be the most effective Michael acceptors. The same reaction conducted by using different molar ratios of the components in this DES showed the eutectic point to be the most effective in terms of the yields observed.

Eutectic phase change composites with MXene nanoparticles for enhanced photothermal absorption and conversion capacity

Phase change composite materials with uniform nanomaterial dispersion are potential solutions for improving thermophysical properties and enhancing latent heat capacity applicable in thermal management. In this study, various transitional carbide-based MXene samples were synthesised via acid etching to augment the heat transfer capacity and efficiency of the solar thermal energy storage (TES). These samples were then uniformly dispersed in a eutectic mixture (1:1) of paraffin wax (PW) and polyethylene glycol (PEG-6000), resulting in the formation of a MePCM composite. The controllable porous structure and hydrogen interactions with the external layer of MXene and long-chain PCM benefitted in the well impregnation of PCM and compatibility impregnated into the composite. An exceptionally higher mass fraction of 1 wt % Ti3C2Tx MXene-based phase change composite unveiled a higher phase change enthalpy of 138.66 J/g in the melting phase and 139.54 J/g in the solidification phase with 89.82 % energy storage efficiency. In contrast to pure eutectic PCM (0.2593 W/mK), the thermal conductivity of MePCM composite is relatively higher and provides a thermal conductivity of 0.9209 W/mK for Ti3C2Tx MXene-based composite. The enhancement of thermal conductivity is ascribed to the increased heat conduction pathway facilitated by the MXene arrangement. The utilisation of spatially constrained eutectic phase change material (PCM) assembly resulted in the development of MePCM, which exhibited enhanced thermal conductivity, chemical and physical stability, and thermal consistency across 500 melting-solidification cycles. Benefitting from the thermal conduction path, the MePCM exhibits an excellent photothermal conversion efficiency of 98.53 %. The thermal responsive tests of Ti3C2Tx and V2CTx MXene composite samples provide better thermal response than eutectic PCM without thermal reduction. With a higher thermal storage capacity and higher heat transfer property, thermally reliable MePCM composites exhibited tremendous potential for photothermal applications.

Eutectogels as Promising Materials in Biocatalysis

AbstractThe entrapment of deep eutectic solvents (DES) and eutectic systems into porous scaffolds renders a new class of soft and nonvolatile materials called eutectogels that have recently stepped into the spotlight in different areas ranging from electronics to drug delivery. Recent progress in the use of DES in biocatalysis, where they have been demonstrated to improve substrate supply, conversion, and enzyme stability, has opened an unparalleled opportunity to exploit the merits of eutectogels for immobilizing biological catalysts. The resulting functional materials could outperform traditional hydrogels and ionic liquid gels, offering fresh perspectives to broaden the application scope of many enzymes. In this perspective, we go into the potential of eutectogels as innovative scaffolds that support biocatalytic reactions and discuss different applications where these systems could show plain benefits compared to traditional materials. Future directions for this newly developed technology are highlighted.

Development of CaCl2·6H2O-mannitol/SiO2 shape-stabilized composite phase change material for the radiant cooling panel system

Radiant cooling panel systems are now popular solution for low carbon buildings, so has received great attention of researchers. Current development, however, is that radiant cooling panel systems have low cooling efficiency and cause high pressure on national energy supply during peak energy consumption periods. This study, therefore, has developed a novel composite phase change material (CPCM) coupled with a typical radiant cooling panel system, providing longer indoor comfort duration and less temperature fluctuation, while also alleviating the pressure on national energy supply during peak energy consumption. In this study, eutectic hydration salt of CaCl2·6H2O and mannitol have been combined with SiO2 to prepare a shape-stabilized CPCM. It has been placed in a test room to justify the impact of the new material. Experimental results have demonstrated some major properties of this material, namely, a melting point of 20.7 °C, a high latent heat value of 119.8 J/g, and a supercooling degree of 1.3 °C, as well as good stability and thermal reliability. Therefore, it can be used as a good solution for radiant cooling panel systems. Comparing the results with another test room with ordinary radiant cooling panels, the room with the new CPCM panel showed less indoor temperature fluctuation and 73 % longer indoor comfort duration. This work provides further development of using hydrated salts and CPCMs with different phase change temperatures in radiant cooling panel systems.

Arginine Acts as both Co-Solvent and Catalyst in Regioselective Eutectic-Mediated Dimerization of Levulinic Acid.

A simple, solvent-free arginine-catalyzed aldol dimerization of levulinic acid was achieved via the simultaneous formation of a eutectic mixture. Dimers of levulinic acid are valued as biomass-derived fine chemical precursors, with potential to upgrade to bio-jet fuels or N-containing functional chemicals. Typically, these dimers are produced as isomeric mixtures using high temperatures and a variety of solid inorganic catalysts or mineral acids. In this study, an organocatalytic and regioselective dimerization was achieved at 22 % conversion on either a bench or kilogram scale using mild temperatures and only L-arginine as both a co-solvent and catalyst. The intricate H-bonding network comprising the eutectic solvent was harnessed to produce only one product, minimizing side reactivity and preserving the reactants for recycling.

All-electrochemical synthesis of SnBi/SnAgCu structures for low-temperature formation of high-reliability solder microjoints

There is a growing interest in low temperature soldering, yet the use of low-melting point alloys for interconnection is often hindered by reliability concerns. Eutectic tin-bismuth (SnBi) alloy is being considered for soldering to Sn3Ag0.5Cu (SAC305) bumps at lower temperatures (150 °C), but the resulting hybrid structures are not very reliable. We have recently shown that superior reliability can be achieved by a post-soldering anneal to distribute up to 6 % Bi throughout the joint. However, the new approach is impractical for solder joints taller than 70 µm and the manufacturing feasibility in such cases warrants both SnBi and SAC305 to be electroplated. The present study utilizes electrochemistry to broaden the applicability of the aforementioned approach by the development of optimized routines for the separate electroplating of both structural alloys. The synthesis of the SAC305 alloy employs elemental co-deposition under strict thickness control, and the SnBi eutectic mixture may be produced likewise and deposited atop to enable low-temperature soldering. If the SnBi is deposited on separate pads, better composition control may be achieved alternatively by the successive plating of both metals, followed by reflow to facilitate their mixing. The established plating routines are further fine-tuned for the processing of an array of pillars.