Search Results (390)

This study evaluates the production of base oils for biolubricants using fatty acid methyl esters (FAMEs) derived from sunflower oil as the raw material. The production process involved the synthesis of oleochemical esters through a single-step alkaline transesterification reaction with a high-molecular-weight polyol, such as trimethylolpropane (TMP). To assess the effectiveness of the developed catalytic system in conducting the transesterification reactions and its impact on the properties of the final product, two types of alkaline catalysts were used. Specifically, the reactions were carried out using either Ca/TEA alkoxide or sodium methoxide as catalysts in various configurations and concentrations to determine the optimal catalyst concentration and reaction conditions. Sodium methoxide served as the commercial benchmark catalyst, while the Ca/TEA alkoxide was prepared in the laboratory. The optimal concentration of Ca/TEA was determined to be 3.0% wt. in the presence of iso-octane and 3.5% wt. under vacuum, while the corresponding concentrations of CH₃ONa for both cases were determined to be 2.0% wt. The synthesized biolubricant esters exhibit remarkable performance characteristics, such as high kinematic viscosities and low pour points—ranging from 33–48 cSt at 40 °C, 7.68–10.03 cSt at 100 °C, to −14 to −7 °C, respectively—which are comparable to or improved over those of mineral oils such as SN-150 or SN-500, with the Ca/TEA alkoxide-catalyzed systems showing superior oxidation stability and reduced byproduct formation. Full article

An anion exchange-assisted technique was used for the synthesis of platinum-decorated SnO₂ supports, providing nanocatalysts with enhanced activity for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). In this study, a series of SnO₂ supports, namely SnA (synthesized almost at room temperature), SnB (hydrothermally treated at 180 °C), and SnC (annealed at 600 °C), are systematically investigated, all loaded with 1 mol% Pt from H₂PtCl₆ under identical mild conditions. The chloride ions from the SnCl₄ precursors were efficiently removed via a strong-base anion exchange reaction, resulting in highly dispersed, crystalline ~5 nm cassiterite SnO₂ particles. All Pt/SnO₂ composites displayed mesoporous structures with type IVa isotherms and H₂-type hysteresis, with SP1a (Pt on SnA) exhibiting the largest surface area (122.6 m²/g) and the smallest pores (~3.5 nm). STEM-HAADF imaging revealed well-dispersed PtOx domains (~0.85 nm), while XPS confirmed the dominant Pt⁴⁺ and Pt²⁺ species, with ~25% Pt⁰ likely resulting from photoreduction and/or interactions with Sn–OH surface groups. Raman spectroscopy revealed three new bands (260–360 cm⁻¹) that were clearly visible in the sample with 10 mol% Pt and were due to the vibrational modes of the PtOx species and Pt-Cl bonds introduced due the addition and hydrolysis of H₂PtCl₆ precursor. TGA/DSC analysis revealed the highest mass loss for SP1a (~7.3%), confirming the strong hydration of the PtOx domains. Despite the predominance of oxidized PtOx species, SP1a exhibited the highest catalytic activity (k_app = 1.27 × 10⁻² s⁻¹) and retained 84.5% activity for the reduction of 4-NP to 4-AP after 10 cycles. This chloride-free low-temperature synthesis route offers a promising and generalizable strategy for the preparation of noble metal-based nanocatalysts on oxide supports with high catalytic activity and reusability. Full article

Heavier element analogues of a ketone, a C=O double-bond compound, have been fascinating compounds from the viewpoint of main-group element chemistry because of their unique structural features and reactivity as compared with those of a ketone, which plays an important role in organic chemistry. We will report here the synthesis of diorgano-stannanethione and stannaneselone featuring tin–chalcogen double bonds, which are the heavy-element analogues of a ketone. The newly obtained stannaneselone has been structurally characterized by spectroscopic analyses and single-crystal X-ray diffraction (SC-XRD) analysis, showing the short Sn–Se bond length featuring π-bond character. The obtained bis(ferrocenyl)stannanechalcogenones were found to undergo [2+4]cycloaddition reactions with 2,3-dimethyl-1,3-butadiene, affording the corresponding six-membered ring compound. Notably, thermolysis of the [2+4]cycloadduct of the stannaneselone regenerated the stannaneselone via the retro[2+4]cycloaddition, whereas the sulfur analogue was thermally very stable. Full article

The WRKY transcription factor family is a significant family of plant transcription factors (TFs). Plant growth and development are often influenced by abiotic factors, such as salinity and low temperature. Numerous studies have demonstrated that WRKY TFs primarily influence plant responses to adversity. However, there are few studies on the role of WRKY genes in the stress responses of Malus baccata (L.) Borkh. We cloned the MbWRKY33 gene from Malus baccata for this research, and its roles in salt stress tolerance were analyzed. Phylogenetic tree analysis revealed that MbWRKY33 and PbWRKY33 have the highest homology. Subcellular localization revealed that MbWRKY33 was located within the nucleus. An analysis of tissue-specific expression showed that MbWRKY33 had relatively high expression levels in young leaves and roots. Moreover, Arabidopsis thaliana plants overexpressing MbWRKY33 exhibited stronger resistance to salt stress compared with the wild type (WT) and the unloaded line empty vector (UL). Under the treatment of 200 mM NaCl, transgenic Arabidopsis thaliana plants exhibited significantly higher activities of antioxidant enzymes like superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) than the control. In contrast, the WT and the UL lines had elevated levels of malondialdehyde (MDA) and reactive oxygen species (ROS). In addition, MbWRKY33 elevates transgenic plant resistance to salt stress by regulating the expression levels of AtNHX1, AtSOS1, AtSOS3, AtNCED3, AtSnRK2, and AtRD29a. Results indicated that MbWRKY33 in Malus might be linked to high-salinity stress responses, laying a foundation for understanding WRKY TFs’ reaction to such stress. Full article

This study investigates the interfacial reactions of FeCoNiCr and FeCoNiMn medium-entropy alloys (MEAs) with Sn and Sn-3Ag-0.5Cu (SAC305) solders at 250 °C. The evolution of interfacial microstructures is analyzed over various aging periods. For comparison, the FeCoNiCrMn high-entropy alloy (HEA) is also examined. In the Sn/FeCoNiCr system, a faceted (Fe,Cr,Co)Sn₂ layer initially forms at the interface. Upon aging, the significant spalling of large (Fe,Cr,Co)Sn₂ particulates into the solder matrix occurs. Additionally, an extremely large, plate-like (Co,Ni)Sn₄ phase forms at a later stage. In contrast, the Sn/FeCoNiMn reaction produces a finer-grained (Fe,Co,Mn)Sn₂ phase dispersed in the solder, accompanied by the formation of the large (Co,Ni)Sn₄ phase. This observation suggests that Mn promotes the formation of finer intermetallic compounds (IMCs), while Cr facilitates the spalling of larger IMC particulates. The Sn/FeCoNiCrMn system exhibits stable interfacial behavior, with the (Fe,Cr,Co)Sn₂ layer showing no significant changes over time. The interfacial behavior and microstructure are primarily governed by the dissolution of the constituent elements and composition ratio of the HEAs, as well as their interactions with Sn. Similar trends are observed in the SAC305 solder reactions, where a larger amount of fine (Fe,Co,Cu)Sn₂ particles spall from the interface. This behavior is likely attributed to Cu doping, which enhances nucleation and stabilizes the IMC phases, promoting the formation of finer particles. The wettability of SAC305 solder on MEA/HEA substrates was further evaluated by contact angle measurements. These findings suggest that the presence of Mn in the substrate enhances the wettability of the solder. Full article

Four silane-containing Schiff base oligomers (o-SBNs and o-SBBs) were synthesized by high-temperature polycondensation reactions using silicon-based dialdehydes with naphthalene and 1,1’-binaphthalene diamine derivates. The samples showed a moderate solubility in common organic solvents, where the incorporation of TPS cores into o-SBN2 allows the formation of highly soluble material in non-polar solvents with higher molecular weights (11.58 kDa) and polydispersity. All oligo-SBs displayed high thermal resistance (above 450 °C), showing enhanced thermal stability for TPS-containing oligomers, with the degradation temperature exceeding 530 °C (o-SBB2) and high T_g values due to the higher aromatic content granted by TPS and 1,1’-binaphthalene moieties. Optical results of the oligo-SBs showed broad absorption and emission behavior in the visible spectrum, ranging from deep blue (o-SBN1 and o-SBB1) to blue (o-SBN2 and o-SBB2). The structure promotes a clear bathochromic shift for TPS-based oligomers, attributed to an extended π-conjugation across the backbone. In addition, the π-π overlap effect highlights larger Stokes shifts for the DMS core oligomers o-SN2 (133 nm) and o-SBB1 (195 nm). The oligo-SBs were found to be wide-bandgap materials, with E_g^opt values in the range of 2.60 eV to 3.67 eV. The higher molecular weight of o-SBN2, which provided an extended π-conjugation, allows the lowest value of E_g^opt (2.60 eV) to be achieved. In addition, DFT, TDDFT and EDDM calculations were performed on trimeric oligo-SBs, revealing that HOMOs are localized in the amine-terminal fraction, while LUMOs are localized over the terminal aldehyde groups. These findings highlight the used DMS and TPS cores in Schiff base materials, providing valuable insights into fine-tuning physicochemical properties through the use of suitable building blocks and their potential as optoelectronic materials. Full article

Vibration spectroscopy is routinely used in analytical chemistry for molecular speciation. Less common is its use in studying the dynamics of reaction and transport processes. A shortcoming of vibration spectroscopies is that they are not inherently specific to chemical elements. Progress in synchrotron radiation-based X-ray technology has developed nuclear resonance vibration spectroscopy (NRVS), which can be used to produce element-specific vibration spectra and partial vibrational density of states (PVDOS), provided the material under investigation contains a Mössbauer-active element. While the method has been recently used successfully for protein spectroscopy, fewer studies have been conducted for condensed matter. We have employed NRVS on the BaSnO₃ perovskite structure, which is a model compound for ceramic proton conductors in intermediate temperature fuel cells. Since we used ¹¹⁹Sn as a Mössbauer isotope, the derived experimental PVDOS is specific to the element Sn in BaSnO₃. We show how this phonon DOS is used as an experimental anchor for the interpretation of the DFT-calculated PVDOS of BaSnO₃. Full article

The challenging problem of chlorine “poisoning” SnO₂ for poorly recoverable detection of dichloromethane has been solved in this work. The materials synthesized by Ni or/and Mo doping SnO₂ were spread onto the micro-hotplates (<1 mm³) to fabricate the MEMS sensors with a low power consumption (<45 mW). The sensor based on Mo·Ni co-doped SnO₂ is evidenced to have the best sensing performance of significant response and recoverability to dichloromethane between 0.07 and 100 ppm at the optimized temperature of 310 °C, in comparison with other sensors in this work and the literature. It can be attributed to a synergetic effect of Mo·Ni co-doping into SnO₂ as being supported by characterization of geometrical and electronic structures. The sensing mechanism of dichloromethane on the material is investigated. In situ infrared spectroscopy (IR) peaks identify that the corresponding adsorbed species are too strong to desorb, although it has demonstrated a good recoverability of the material. A probable reason is the formation rates of the strongly adsorbed species are much slower than those of the weakly adsorbed species, which are difficult to form significant IR peaks but easy to desorb, thus enabling the material to recover. Theoretical analysis suggests that the response process is kinetically determined by molecular transport onto the surface due to the free convection from the concentration gradient during the redox reaction, and the output steady voltage thermodynamically follows the equation only formally identical to the Langmuir–Freundlich equation for physisorption but is newly derived from statistical mechanics. Full article

The current environmental pollution and energy crises are global concerns that must be addressed. Considering this background, three perovskites (YMnO₃, Co-doped YMnO₃, and Sn-doped YMnO₃) were synthesized via a sol–gel method and characterized by XRD, SEM, and EDX. Their water-splitting electrocatalytic activity was evaluated in a strongly alkaline medium. The highest activity was observed during hydrogen evolution reaction (HER) experiments on a glassy carbon electrode coated with a catalyst ink containing the Co-doped material. Initially, the HER overpotential value at −10 mA/cm² was 0.59 V, and the Tafel slope was 115 mV/dec. Following a chronoamperometric stability test, the overpotential became 0.46 V and the Tafel slope 119 mV/dec. The higher HER activity of the modified electrode is ascribed to a higher number of catalytic sites exposed to the electrolyte solution and the presence of Carbon Black. The photocatalytic activity of the perovskites was investigated as well, using different experimental conditions and simulated solar irradiation. The results show that the photocatalytic activity can be improved by doping, and the highest removal efficiency is achieved in the presence of the Co-doped YMnO₃ when ~60% of 17α-ethynylestradiol is degraded. Furthermore, the initial pH has no favorable effect on the degradation efficiency. The reusability of Co-doped YMnO₃ was also tested and minimal activity loss was found after three photocatalytic cycles. Full article

The co-addition of chromium (Cr) and tin (Sn) is known to enhance the wettability between copper (Cu) and graphite (C_gr), but the effect of Sn content remains poorly understood. This study aims to systematically investigate the influence of Sn content a (a = 0, 10, 20, 30, 40, 50, 80, 99 at. %) on the wettability, interfacial structure, surface/interface energy (σ_lv/σ_sl), and adhesion behavior of the Cu–aSn–1Cr/C_gr system at 1100 °C. The experimental results show that as the Sn content increases, the equilibrium contact angle (θ_e) of the metal droplet shows a non-monotonic trend; the thickness of the reaction product layer (RPL, consisting of Cr carbides (Cr_mC_n)) gradually increases, accompanied by a decrease in the calculated adhesion work ($W_{\mathrm{ad}}^{\mathrm{cal}}$). A “sandwich” interface structure is observed, consisting of two interfaces: metal||Cr_mC_n and Cr_mC_n||C_gr. Sn content mainly affects the former. At metal||Cr_mC_n, Sn exists in various forms (e.g., Cu–Sn solid solution, Cu_xSn_y compounds) in contact with Cr_mC_n. To elucidate the wetting and bonding mechanisms of metal||Cr_mC_n, simplified interfacial models are constructed and analyzed based on first-principles calculations of density functional theory (DFT). The trend of theoretically calculated results (σ_metal and W_ad) agrees with the experimental results (σ_lv and $W_{\mathrm{ad}}^{\mathrm{cal}}$). Further analysis of the partial density of state (PDOS) and charge density difference (CDD) reveals that charge distribution and bonding characteristics vary with Sn content, providing the microscopic insight into the nature of wettability and interfacial bonding strength. Full article

With the enhancement of environmental protection awareness and the implementation of related regulations, lead-free soldering materials are gradually replacing the traditional leaded soldering materials in the field of electronics manufacturing. Sn–Ag soldering materials have become a research hotspot because of their good mechanical properties, solderability, and thermal fatigue reliability, but their high cost limits their large-scale application. The low silver content of the Sn–Ag solder reduces the cost while maintaining an excellent performance. However, as the size of electronic components shrinks and the package density increases, the solder joint spacing decreases, the potential gradient increases, and electrochemical migration (ECM) becomes a key factor affecting the reliability of solder joints. In this study, the ECM failure process was simulated by the water droplet method, and the SEM and XPS analyses were utilized to investigate the ECM mechanism of Sn1.0Ag solder alloys, and the effects of different concentrations of NaCl solutions on their ECM were investigated. The results showed that the ECM of the Sn1.0Ag solder occurred in a 0.01 M NaCl solution, the dendritic composition was pure Sn, and the white precipitate was a mixture of Sn(OH)₂ and Sn(OH)₄. With the increase in the NaCl concentration, the corrosion resistance of the Sn1.0Ag solder alloy decreases and the ECM reaction intensifies, but with a high concentration of the NaCl solution, a large amount of precipitation hinders the migration of Sn ions, resulting in the generation of no dendrites. The present study provides new insights into the ECM behavior of a low-silver-content Sn–Ag solder system. Full article

Purine-1,4,7,10-tetraazacyclododecane (cyclen) conjugate was designed to study its Cu²⁺ ions complexation capability. Several synthetic approaches were tested to achieve the target compound. The optimal approach involved stepwise modifications of purine N9, C8, and C6 positions that, in nine consecutive steps, provided purine–cyclen conjugate. The synthetic sequence involved Mitsunobu-type alkylation at N9 and iodination at C8, followed by Stille, S_NAr, CuAAC, and alkylation reactions. The designed purine–cyclen conjugate is able to complex Cu²⁺ ions in both the cyclen part and between the purine N7 and triazole N2 positions. The complexation pattern and equilibrium were studied using the NMR titration technique in MeCN-d₃ and absorption spectra. Full article

N-Acylethanolamines (NAEs) are a class of lipid mediators that consist of long-chain fatty acids condensed with ethanolamine and exert various biological activities depending on their fatty acyl groups. NAEs are biosynthesized from membrane phospholipids by two-step reactions or alternative multi-step reactions. In the first reaction, N-acyltransferases transfer an acyl chain from the sn-1 position of phospholipids to the amino group (N position) of phosphatidylethanolamine (PE), generating N-acyl-PE (NAPE), a precursor of NAE. So far, two types of N-acyltransferases have been identified with different levels of Ca²⁺-dependency: cytosolic phospholipase A₂ ε (cPLA₂ε) as a Ca²⁺-dependent N-acyltransferase and phospholipase A and acyltransferase (PLAAT) enzymes as Ca²⁺-independent N-acyltransferases. Recent in vivo studies using knockout mice with cPLA₂ε and PLAAT enzymes, combined with lipidomic approaches, have clarified their roles in the skin and brain and in other physiological events. In this review, we summarize the current understanding of the functions and properties of these enzymes. Full article

All-solid-state batteries have garnered significant attention due to their potential to exceed the energy density of conventional lithium-ion batteries, particularly when alloying-based materials or lithium metal anodes are used. However, achieving compatibility with lithium metal remains a persistent bottleneck. In this study, we shed light on the potential of SnHPO₃ tin phosphite and Ni_3.4Sn₄ intermetallic as novel conversion/alloying anode materials for all-solid-state lithium batteries using Li₆PS₅Cl as the solid electrolyte. The two Sn-based active materials were nanostructured by ball-milling to demonstrate considerable promise for application in all-solid-state half-cells. Galvanostatic cycling at room temperature revealed electrochemical behavior based on conversion/alloying reactions akin to those observed in conventional lithium-ion batteries. Promisingly, both materials exhibited satisfying electrochemical stability, with coulombic efficiencies exceeding 97%. These findings indicate that Li₆PS₅Cl solid electrolyte is compatible with Sn-based alloying anodes. Full article

The development of heterostructures incorporating photocatalysts optimized for visible-light activity represents a major breakthrough in the field of environmental remediation research, offering innovative and sustainable solutions for environmental purification. This study explores the photocatalytic capabilities of a SnFe₂O₄/g-C₃N₄ heterojunction nanocomposite, successfully synthesized from graphitic carbon nitride (g-C₃N₄) and tin ferrate (SnFe₂O₄) and applied to the degradation of the cationic dye brilliant cresyl blue (BCB) in an aqueous solution. These two components are particularly attractive due to their low cost and ease of fabrication. Various characterization techniques, including XRD, FTIR, SEM, and TEM, were used to confirm the successful integration of SnFe₂O₄ and g-C₃N₄ phases in the synthesized catalysts. The photocatalytic and photo-Fenton-like activity of the heterojunction composites was evaluated by the degradation of brilliant cresyl blue under visible LED illumination. Compared to the pure components SnFe₂O₄ and g-C₃N₄, the SnFe₂O₄/g-C₃N₄ nanocomposite demonstrated a superior photocatalytic performance. Furthermore, the photo-Fenton-like performance of the composites is much higher than the photocatalytic performances. The significant improvement in photo-Fenton activity is attributed to the synergistic effect between SnFe₂O₄ and g-C₃N₄, as well as the efficient separation of photoexcited electron/hole pairs. The recyclability of the SnFe₂O₄/g-C₃N₄ composite toward BCB photo-Fenton like degradation was also shown. This study aimed to assess the modeling and optimization of photo-Fenton-like removal BCB using the SnFe₂O₄/g-C₃N₄ nanomaterial. The main parameters (photocatalyst dose, initial dye concentration, H₂O₂ volume, and reaction time) affecting this system were modeled by two approaches: a response surface methodology (RSM) based on a Box–Behnken design and artificial neural network (ANN). A comparison was made between the predictive accuracy of RSM for brilliant cresyl blue (BCB) removal and that of the artificial neural network (ANN) approach. Both methodologies provided satisfactory and comparable predictions, achieving R² values of 0.97 for RSM and 0.99 for ANN. Full article