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451.
Fujimori DG Barr EW Matthews ML Koch GM Yonce JR Walsh CT Bollinger JM Krebs C Riggs-Gelasco PJ 《Journal of the American Chemical Society》2007,129(44):13408-13409
452.
Williams M Okasha RM Nairn J Twamley B Afifi TH Shapiro PJ 《Chemical communications (Cambridge, England)》2007,(30):3177-3179
Ternary clusters Cu(9)In(10)S(9)(SEt)(21)(PPh(3))(3) and Cu(11)In(6)S(7)(S(t)Bu)(15) were isolated from the UV-photolysis products of precursors (PPh(3))(2)CuIn(SEt)(4) and (PPh(3))(2)CuIn(S(t)Bu)(4), respectively, and structurally characterized. 相似文献
453.
The rate constant, k, for the homogeneous electron transfer (self-exchange) reaction between the diamagnetic bis(maleonitriledithiolato)nickel dianion, [Ni(mnt) 2] (2-), and the paramagnetic monoanion, [Ni(mnt) 2] (1-), has been determined in acetone and nitromethane (CH 3NO 2) using (13)C NMR line widths at 22 degrees C (mnt = 1,2-S 2C 2(CN) 2). The values of k (2.91 x 10 (6) M (-1) s (-1) in acetone, 5.78 x 10 (6) M (-1) s (-1) in CH 3NO 2) are faster than those for the electron transfer reactions of other Ni(III,II) couples; the structures of [Ni(mnt) 2] (1-) and [Ni(mnt) 2] (2-) allow for a favorable overlap that lowers the free energy of activation. The values of k are consistent with the predictions of Marcus theory. In addition to k, the spin-lattice relaxation time, T 1e, of [Ni(mnt) 2] (1-) is obtained from the NMR line width analysis; the values are consistent with those predicted by spin relaxation theory. 相似文献
454.
Novel Cyclic Enaminone Esters and N‐Heterocycles by Divergent Chemical Behavior through Amine‐Mediated Reactions
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Liliana E. Luna Walter Tontarelli Pamela Forastieri Raquel M. Cravero 《Helvetica chimica acta》2015,98(7):994-1003
New acridinones and enaminone esters were synthesized by microwave‐assisted tandem‐Michael? Michael addition and cyclization from cyclohexane‐1,3‐diones. The reaction mechanism for both open and closed structures, and the presence of intramolecular twelve‐membered rings derived from NH and OH H‐bonds of enaminone esters are discussed. 相似文献
455.
Audrey Bianchi Pamela R. Rivera-Tovar Vanesa Sanz Tania Ferreira-Anta María Dolores Torres Jos Ricardo Prez-Correa Herminia Domínguez 《Molecules (Basel, Switzerland)》2021,26(21)
Aristotelia chilensis is a plant rich in phenolics and other bioactive compounds. Their leaves are discarded as waste in the maqui berry industry. A new application of these wastes is intended by the recovery of bioactive compounds using pressurized hot water extraction with conventional or microwave heating. Both technologies have been selected for their green character regarding the type of solvent and the high efficiency in shorter operation times. Extractions were performed in the temperature range 140–200 °C with a solid/liquid ratio of 1:15 (w:w). The extracts’ total phenolic content, antioxidant capacity, and saccharides content obtained with both heating methods were measured. Additionally, the thermo-rheological properties of the gelling matrix enriched with these extracts were analyzed. Optimum conditions for lyophilized extracts were found with conventional heating, at 140 °C and 20 min extraction; 250.0 mg GAE/g dry extract and 1321.5 mg Trolox/g dry extract. Close to optimum performance was achieved with microwave heating in a fraction of the time (5 min) at 160 °C (extraction), yielding extracts with 231.9 mg GAE/g dry extract of total phenolics and antiradical capacity equivalent to 1176.3 mg Trolox/g dry extract. Slightly higher antioxidant values were identified for spray-dried extracts (between 5% for phenolic content and 2.5% for antioxidant capacity). The extracts obtained with both heating methods at 200 °C contained more than 20% oligosaccharides, primarily glucose. All the formulated gelling matrices enriched with the obtained extracts displayed intermediate gel strength properties. The tested technologies efficiently recovered highly active antioxidant extracts, rich in polyphenolics, and valuable for formulating gelling matrices with potential applicability in foods and other products. 相似文献
456.
Saffron is a widespread consumed spice containing many phytochemicals. It is often used in dairy technologies to enhance color and flavor of cheeses, but it is also known for its several therapeutic effects, as well as its antiproliferative and anticancer properties. In this study High Performance Liquid Chromatography was used to characterize saffron bioactive compounds in cow and ewe cheeses made with saffron, and the antiproliferative effect of the crocin-rich extracts from cheeses was investigated on different cellular lines (CaCo2, MDA-MB-231 and HeLa) by MTT assay. Crocins were observed in all cheese samples, with the total content ranging between 0.54 and 30.57 mg trans-4-GG/100 g cheese, according to the different cheese making process. Picrocrocin was detected in no cheese (probably due to its degradation during cheese making), while safranal was detected only in one ewe cheese (mainly due to its high volatility). HeLa and MDA-MB-231 cells were sensitive to treatment with crocin-rich extracts from cheeses, while no effect was observed on CaCo2 cells. The chemical environment of the food matrix seems to have a great influence on the crocin antiproliferative effect: the crocin-rich extracts from cheese with both high residual N/protein and fat contents showed increased antiproliferative effect compared to pure crocin (trans-4-GG), but cheeses from different milk species (type of fats and proteins) could also play an important role in modulating crocin’s antiproliferative effects. 相似文献
457.
458.
Tandokazi Pamela Magangana Nokwanda P. Makunga Olaniyi Amos Fawole Maria A. Stander Umezuruike Linus Opara 《Molecules (Basel, Switzerland)》2022,27(9)
Hot water blanching at 80 °C for 3 min can be used as a novel pre-treatment step in pomegranate peel to preserve the integrity of the phytochemical content within the peel extracts by lowering or inactivating enzymes such as polyphenol (PPO) oxidase and peroxidase (POD) that are responsible for the break-down of phytochemicals within the peel. The aim of this study was to investigate the effect of hot water blanching pre-treatment on yield, bioactive compounds, antioxidants, enzyme inactivation, and antibacterial activity of ‘Wonderful’, ‘Acco’, and ‘Herskawitz’ pomegranate peel extracts. We used a variety of spectrophotometric-based assays and liquid chromatography mass spectrometry (LC-MS)-based approach to characterize and quantify metabolites within the peel extracts. Blanching significantly (p < 0.05) reduced PPO activity in all peel extracts, with the highest PPO reduction in ‘Herskawitz’ peel extracts at 0.25 U/mL. Furthermore, higher antioxidant activity in ‘Herskawitz’ blanched peel extracts using 2,2-diphenyl-1-picryl hydrazyl (DPPH) antioxidant activity, ferric ion reducing antioxidant power (FRAP), and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical scavenging activity at 567.78 ± 9.47 µmol Trolox/g DM, 800.05 ± 1.60 µmol Trolox/g DM, and 915.27 ± 0.61 µmol Trolox/g DM, respectively, was noted. ‘Herskawitz’ blanched peel extracts were recorded with the lowest minimum inhibitory concentration (MIC) value of 80 µg/mL for Gram-positive Bacillus subtilis and Gram-negative Klebsiella pneumoniae bacteria strains. A total of 30 metabolites were present in ‘Acco’ and ‘Herskawitz’ peel extracts and were tentatively identified after LC-MS profiling. This study demonstrates that blanched peel extracts from ‘Herskawitz’ cultivar have great potential for commercial use in value-added products in the nutraceutical, cosmeceutical, and pharmacological industries. 相似文献
459.
Mergen H. Ghayesh Siavash Kazemirad Mohammad A. Darabi Pamela Woo 《Archive of Applied Mechanics (Ingenieur Archiv)》2012,82(3):317-331
Thermo-mechanical vibrations of a simply supported spring-mass-beam system are investigated analytically in this paper. Taking
into account the thermal effects, the nonlinear equations of motion and internal/external boundary conditions are derived
through Hamilton’s principle and constitutive relations. Under quasi-static assumptions, the equations governing the longitudinal
motion are transformed into functions of transverse displacements, which results in three integro-partial differential equations
with coupling terms. These are solved using the direct multiple-scale method, leading to closed-form solutions for the mode
functions, nonlinear natural frequencies and frequency–response curves of the system. The influence of system parameters on
the linear and nonlinear natural frequencies, mode functions, and frequency–response curves is studied through numerical parametric
analysis. It is shown that the vibration characteristics depend on the mid-plane stretching, intra-span spring, point mass,
and temperature change. 相似文献
460.
Pamela J. Hagrman Douglas Hagrman Jon Zubieta 《Angewandte Chemie (International ed. in English)》1999,38(18):2638-2684
A blueprint for the design of oxide materials is provided by nature. By borrowing from nature's ability to influence inorganic microstructures in biomineralization processes and in the hydrothermal synthesis of complex minerals, a new class of materials in which organic components exert a role in controlling inorganic microstructure is evolving. By employing members of the ever-expanding class of polymeric coordination complex cations, novel molybdenum oxide substructures, such as the one shown, may be prepared. 相似文献