Equilibrium, thermodynamics and kinetics study on Au(III) extraction by gemini surfactant with different spacer length

The effect of spacer lengths of imidazolium gemini surfactant [C14-n-C14im]Br2 (n = 2, 4, 6) on the equilibrium, thermodynamics and kinetics of Au(III) extraction from hydrochloric acid medium were investigated in this article. The thermodynamic parameters, including the changes in enthalpy (ΔH*), entropy (ΔS*) and Gibbs free energy (ΔG*) were determined. The values of ΔH* demonstrated that the extraction of Au(III) by [C14-n-C14im]Br2 was endothermic at first and exothermic at last. The kinetics study found that extraction rate became faster when the spacer lengths were increased. Moreover, kinetics results demonstrated that the diffusion is the controlling step, and the mass transfer coefficients of Au(III) in the investigated systems indicated that the resistance of mass transfer was smaller when the spacer lengths was longer. The studies of interfacial tension further confirmed the better extractability of [C14-n-C14im]Br2 with longer spacer lengths. Our results reveal efficient and sustainable gold separation.</p

Surface Tension and Dilational Viscoelasticity of Water in the Presence of Surfactants Tyloxapol and Triton X-100 with Cetyl Trimethylammonium Bromide at 25 °C

Surface tension and dilational viscoelasticity of water in the presence of surfactants Tyloxapol and Triton X-100 with cetyl trimethylammonium Bromide (CTAB) at 25 °C are investigated. The results show that there is synergistic behavior in both the mixtures at higher mole fraction of nonionic surfactant. According to the Rubingh and Rosen theory, the results predict nonideal mixing and attractive interaction between the constituent surfactants in the mixed micelle and layer. By using the Maeda theory, the results suggest the chain−chain interaction among surfactants does not seem to be high. The surface dilational viscoelasticity results show that the Tyloxapol adsorption layer has the highest dilational modulus |ε| value among three single surfactants. Also, it indicates the |ε| maximum values of surfactant mixtures are usually between that of the single surfactant. Moreover, it is worth noting that the |ε| maximum values of Tyloxapol/CTAB mixtures are always higher than those of TX-100/CTAB ones

Supplementary document for Broad-band-enhanced plasmonic random laser in silver nanostar arrays - 6952021.pdf

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Coassembly of Mixed Weakley-Type Polyoxometalates to Novel Nanoflowers with Tunable Fluorescence for the Detection of Toluene

In this work, three-dimensional nanoflowers with tunable fluorescent properties constructed with mixed Weakley-type polyoxometalates (POMs, Na₉[LnW₁₀O₃₆]·32H₂O, Ln = Eu, Tb, abbreviated to LnW₁₀) and tetraethylenepentamine (TEPA) have been successfully prepared through a facile ionic self-assembly (ISA) method. The shape and petal size of the nanoflower as well as its fluorescent behaviors can be tuned through varying the ratio of EuW₁₀/TbW₁₀. The varied-temperature emission behaviors at 80–260 K show that the fluorescent intensity of both Tb³⁺ and Eu³⁺ decreased with the increase in temperature, which makes them potential luminescent ratiometric thermometers. Moreover, after being mixed with polydimethylsiloxane (PDMS), the as-formed hybrid films showed stable fluorescence along with good transparency. The robustness of the hybrid films was also demonstrated by corrosion resistance upon treatment with strong acid and alkali and thus can be used as a sensor to detect toluene circularly. Our results provide a new avenue to the facile construction of fluorescent composites and demonstrate that the POM complexes can be further used in supramolecular chemistry and nanomaterials

Supplementary document for Broad-band-enhanced plasmonic random laser in silver nanostar arrays - 6908545.pdf

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Supplementary document for Broad-band-enhanced plasmonic random laser in silver nanostar arrays - 6975101.pdf

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Data_Sheet_1_Dynamic Changes in Membrane Lipid Metabolism and Antioxidant Defense During Soybean (Glycine max L. Merr.) Seed Aging.xlsx

Seed viability depends upon the maintenance of functional lipids; however, how membrane lipid components dynamically change during the seed aging process remains obscure. Seed storage is accompanied by the oxidation of membrane lipids and loss of seed viability. Understanding membrane lipid changes and their effect on the cell membrane during seed aging can contribute to revealing the mechanism of seed longevity. In this study, the potential relationship between oxidative stress and membrane lipid metabolism was evaluated by using a non-targeted lipidomics approach during artificial aging of Glycine max L. Merr. Zhongdou No. 27 seeds. We determined changes in reactive oxygen species, malondialdehyde content, and membrane permeability and assessed antioxidant system activity. We found that decreased non-enzymatic antioxidant contents and catalase activity might lead to reactive oxygen species accumulation, resulting in higher electrolyte leakage and lipid peroxidation. The significantly decreased phospholipids and increased glycerolipids and lysophospholipids suggested that hydrolysis of phospholipids to form glycerolipids and lysophospholipids could be the primary pathway of membrane metabolism during seed aging. Moreover, the ratio of phosphatidylcholine to phosphatidylethanolamine, double bond index, and acyl chain length of phospholipids were found to jointly regulate membrane function. In addition, the observed changes in lipid metabolism suggest novel potential hallmarks of soybean seed aging, such as diacylglycerol 36:4; phosphatidylcholine 34:2, 36:2, and 36:4; and phosphatidylethanolamine 34:2. This knowledge can be of great significance for elucidating the molecular mechanism underlying seed aging and germplasm conservation.</p

Solvent-Induced Self-Assembly of Copper Nanoclusters for White Light Emitting Diodes

As a type of luminescent material, copper nanoclusters (Cu NCs) are widely concerned because of their low cost, nontoxicity, and outstanding biocompatibility. However, research studies on the preparation of hydrophobic Cu NCs with high quantum yield can be improved. In this work, we first synthesized atomically precise triphenylphosphine (PPh3)-capped Cu NCs (Cu4–NCs). Second, we adopted solvent engineering strategies to trigger the self-assembly of Cu4–NCs into the assembly with branched structures, thereby achieving aggregation-induced emission (AIE), thermally activated delayed fluorescence (TADF), and a high absolute quantum yield of 67.05%. Moreover, we performed structural characterization and optical analysis, which revealed that the high compactness of the assembly enhances the cuprophilic interaction and suppresses the intramolecular vibration and rotation of the Cu4–NCs ligand, protecting the Cu core from singlet oxygen quenching. These properties lead to the emergence of TADF and AIE. By mixing the as-assembled Cu4–NCs with commercial phosphors, a white light emitting diode prototype can be fabricated. This research demonstrates that TADF emission and the robust luminescence structure of the Cu4–NCs assembly provide them a high application value and extend the research opportunities for metal NCs in optical devices

Self-Assembly of Europium-Containing Polyoxometalates/Tetranalkyl Ammonium with Enhanced Emission for Cu2+ Detection

Lanthanide-containing polyoxometalates (POMs) can be used to detect various materials, but their luminescence in water has suffered enormous limitations due to the strong fluorescence quenching. Herein, to resolve this problem, three-dimensional nanoparticles built by mixed Weakley-type europium-containing POMs (Na9[EuW10O36]·32H2O, abbreviated to EuW10) and tetra-n-alkyl ammonium (TA) with enhanced fluorescent properties have been designed in aqueous solution using an ionic self-assembly (ISA) technique, which is mainly driven by the electrostatic interaction between EuW10 and TA. The morphology and fluorescent properties of the system as well as some influencing factors (alkyl chain length, amino group, and inorganic salt concentration) were systematically investigated. The results indicated that the fluorescent intensity of EuW10/tetramethylammonium bromide (TMAB) composite increased about 14 times, whereas the extent of increase of fluorescence for EuW10/tetraethylammonium bromide (TEAB) and EuW10/tetrabutylammonium bromide (TMAB) composites gradually decrease due to the bulkier steric hindrance of the longer alkyl chain. Besides, the luminescence of EuW10/TMAB nanoparticles is pH responsive, and the reversibility of their structures and luminescence can be realized upon the addition of NaOH/HCl. Moreover, the EuW10/TMAB system also shows great fluorescence-sensing behavior, which could detect Cu2+ with a detection limit of 0.15 μM. Our work provides a facile construction strategy for a functional fluorescent complex via POMs-based supramolecular self-assembly in aqueous solution, which will be further used in biomarkers and sensors

Manipulation of the Gel Behavior of Biological Surfactant Sodium Deoxycholate by Amino Acids

Supramolecular hydrogels were prepared in the mixtures of biological surfactant sodium deoxycholate (NaDC) and halide salts (NaCl and NaBr) in sodium phosphate buffer. It is very interesting that with the addition of two kinds of amino acids (l-lysine and l-arginine) to NaDC/NaX hydrogels, the gel becomes solution at room temperature. We characterized this performance through phase behavior observation, transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared spectra, and rheological measurements. The results demonstrate that the gels are formed by intertwined fibrils, which are induced by enormous cycles of NaDC molecules driven by comprehensive noncovalent interactions, especially the hydrogen bonds. Our conclusion is that the presence of halide salts (NaCl and NaBr) enhances the formation of the gels, while the addition of amino acids (l-lysine and l-arginine) could make the breakage of the hydrogen bonds and weaken the formation of the gels. Moreover, its fast disassembly in the presence of amino acids allows for the release of substances (i.e., the dye methylene blue) entrapped within the gel network. The tunable gel morphology, microstructure, mechanical strength, and anisotropy verify the role of halide salts and amino acids in altering the properties of the gels, which can probably be exploited for a variety of applications in future