The Quantitation of Aqueous Aluminum, P.R. Bloom and M.S. Erich Aqueous Equilibrium Data for Mononuclear Aluminum Species, D.K. Nordstrom and H.M. May Inorganic Aluminum Bearing Solid Phases, B.S. Hemingway and G. Sposito Aqueous Polynuclear Aluminum Species, P.M. Bertsch and D.R. Parker Environmental Chemistry of Aluminum-Organic Complexes, G.F. Vance, F.J. Stevenson, and F.J. Sikora Surface Reactions of Aqueous Aluminum Species, P.M. Jardine and L.W. Zelazny The Surface Chemistry of Aluminum Oxides and Hydroxides, S.R. Goldberg, J.A. Davis, and J.D. Hem The Solubility of Aluminum in Soils, W.L. Lindsay and P.M. Walthall The Chemistry of Aluminum in Surface Waters, C.T. Driscoll and K.M. Postek Aluminum Geochemistry at the Catchment Scale in Watersheds Influenced by Acidic Precipitation, W.H. Hendershot, F. Courchesne, and D.S. Jeffries Index
The traditional small molecular rubber antioxidants have the shortcomings of single function, toxicity, and heavy dependence on non-renewable fossil resources, which limits their green, high-efficiency, and sustainable development in the rubber industry. To address this problem, in this work, we first developed a chitosan derivative containing 10-undecenoyl groups (COS-UC) and then combined it with the natural small molecular antioxidant gallic acid (GA) to prepare chitosan derivative containing 10-undecenoyl and galloyl groups (COS-UC-GA). The obtained COS-UC-GA was used as multifunctional modifier and applied in styrene-butadiene rubber (SBR)/silica composites. The effects of COS-UC-GA on the curing characteristics, crosslinking density, morphology, mechanical properties, and interfacial interaction of SBR/silica composites were explored in detail. The results indicated that the COS-UC-GA can effectively accelerate the vulcanization process of SBR/silica compounds, promote the uniform dispersion of silica, improve the mechanical properties of SBR/silica composites, and significantly enhance the interfacial interaction between the silica and rubber. This research provides a new perspective for developing green and eco-friendly multifunctional modifiers, which not only contributes to the comprehensive utilization of biomass resources, but also can promote the green development of the rubber industry.
Sandra A. V. Eremia, Camelia Albu, Gabriel L. Radu
et al.
In recent years, the wine industry has shown a considerable degree of interest in the occurrence of melatonin in wines. Sample pretreatment may be the most important step in trace analysis. Since wine is a complex matrix and melatonin is present in low amounts (ppb), an adequate extraction technique is required. In this study, the effect of several extraction methods, such as solid phase extraction (SPE), Quick, Easy, Cheap, Effective, Rugged, and Safe extraction (QuEChERS), and dispersive liquid–liquid micro-extraction (DLLME) was studied and the variable parameters that can arise throughout the extraction process were optimized to obtain the best results. A high-performance liquid chromatography with fluorescence detector (HPLC-FL) method was adapted and validated, including measurement uncertainty, for the analysis of melatonin in wines and to assess the efficiency of the extraction yield. After comparing the acquired results, the DLLME method was optimized. Extraction recoveries values ranging from 95 to 104% demonstrated that the approach may be successfully applied for the extraction and concentration (enrichment factor of almost eight) of melatonin in wine samples prior to HPLC-FL analysis. The first report of melatonin levels in Feteasca Neagra wines has been made. The data obtained for Cabernet Sauvignon revealed that the final levels of melatonin in the wines are dependent on the winemaking process.
A two-dimensional (2D) lamellar Zn metal–organic framework (Zn-MOF, <b>1</b>) with a fluorescent 1,6-di(pyridin-3-yl)pyrene (3-DPPy) and 1,4-benzenedicarboxylate (BDC<sup>2−</sup>) bridging linkers was prepared and structurally characterized. The chemical formula of <b>1</b> is [Zn(μ-3-DPPy)(μ-BDC)]<sub>n</sub>. The mononuclear Zn(II) ion, acting as a node, is tetrahedrally coordinated with two 3-DPPy and two BDC linkers. The coordination environment of Zn(II) is a distorted tetrahedral geometry. The Zn-MOF is the <b>sql</b> network structure based on topology analysis. The undulated 2D sheets of <b>1</b> tightly pack together to form a lamellar structure. The pyrene moieties are parallelly oriented to each other. The Zn-MOF is not porous, possibly because the mononuclear Zn(II) node did not form cluster-based secondary building units due to the less symmetric 3-DPPy. The steady-state fluorescence measurements indicate that the fluorescence signal of the <b>1</b> is slightly blue-shifted compared to the free 3-DPPy in the solid state. The excimer emission band at 463 nm for crystalline 3-DPPy is shifted to 447 nm for <b>1</b>. The value of 447 nm is also a blue-shift value compared to nonsubstituted pyrene crystals (470 nm). Despite its nonporosity, the surface Lewis acidic sites of <b>1</b> could catalyze the transesterification of esters. Surface defect sites are responsible for this catalytic activity.
We would like to take this opportunity to highlight the Outstanding Reviewers for Organic Chemistry Frontiers in 2022, as selected by the editorial team for their significant contribution to the journal.