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The rate coefficients for the reactions of C2H and C2D with O2 have been measured in the temperature range 295 K T 700 K. Both reactions show a slightly negative temperature dependence in this temperature range, with kC2H+O2 = (3.15 ± 0.04) × 10−11 (T/295 K)−(0.16 ± 0.02) cm3 molecule−1 s−1. The kinetic isotope effect is kC2H/kC2D = 1.04 ± 0.03 and is constant with temperature to within experimental error. The temperature dependence and the C2H + O2 kinetic isotope effect are consistent with a capture-limited metathesis reaction, and suggest that formation of the initial HCCOO adduct is rate-limiting. 相似文献
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Michael Rhrig Eric L. Petersen David F. Davidson Ronald K. Hanson Craig T. Bowman 《国际化学动力学杂志》1997,29(10):781-789
The rate coefficient of the reaction CH+O2 → products was determined by measuring CH-radical concentration profiles in shock-heated 100–150 ppm ethane/1000 ppm O2 mixtures in Ar using cw, narrow-linewidth laser absorption at 431.131 nm. Comparing the measured CH concentration profiles to ones calculated using a detailed kinetics model, yielded the following average value for the rate coefficient independent of temperature over the range 2200–2600 K: The experimental conditions were chosen such that the calculated profiles were sensitive mainly to the reactions CH+O2 → products and CH3+M → CH+H2+M. For the methyl decomposition reaction channel, the following rate-coefficient expression provided the best fit of the measured CH profiles: Additionally, the rate coefficient of the reaction CH2+H→CH+ H2 was determined indirectly in the same system: © 1997 John Wiley & Sons, Inc. 相似文献
56.
Vernica Ibez Gaspar Jasmin McCaul Hilary Cassidy Craig Slattery Tara McMorrow 《Molecules (Basel, Switzerland)》2021,26(20)
The natural compound curcumin has been shown to have therapeutic potential against a wide range of diseases such as cancer. Curcumin reduces cell viability of renal cell carcinoma (RCC) cells when combined with TNF-related apoptosis-inducing ligand (TRAIL), a cytokine that specifically targets cancer cells, by helping overcome TRAIL resistance. However, the therapeutic effects of curcumin are limited by its low bioavailability. Similar compounds to curcumin with higher bioavailability, such as demethoxycurcumin (DMC) and 3,5-bis(2-fluorobenzylidene)-4-piperidone (EF24), can potentially have similar anticancer effects and show a similar synergy with TRAIL, thus reducing RCC viability. This study aims to show the effects of DMC and EF24 in combination with TRAIL at reducing ACHN cell viability and ACHN cell migration. It also shows the changes in death receptor 4 (DR4) expression after treatment with these compounds individually and in combination with TRAIL, which can play a role in their mechanism of action. 相似文献
57.
Lee J. Silverberg Tapas K. Mal Carlos N. Pacheco Megan L. Povelones Madeline F. Malfara Anthony F. Lagalante Mark A. Olsen Hemant P. Yennawar Hany F. Sobhi Kayla R. Baney Robin L. Bozeman Craig S. Eroh Michael J. Fleming Tracy L. Garcia Casey L. Gregory Julia E. Hahn Alyssa M. Hatter Lexi L. Johns Tianna L. Klinger Jennie J. Li Andrew J. Menig Grace C. Muench Melissa E. Ramirez Jordyn Reilly Nicole Sacco Alexandra M. Sheidy Marla M. Stoner Eric N. Thompson Soroush F. Yazdani 《Molecules (Basel, Switzerland)》2021,26(20)
A series of fourteen 2-aryl-3-phenyl-2,3-dihydro-4H-pyrido[3,2-e][1,3]thiazin-4-ones was prepared at room temperature by T3P-mediated cyclization of N-phenyl-C-aryl imines with thionicotinic acid, two difficult substrates. The reactions were operationally simple, did not require specialized equipment or anhydrous solvents, could be performed as either two or three component reactions, and gave moderate–good yields as high as 63%. This provides ready access to N-phenyl compounds in this family, which have been generally difficult to prepare. As part of the study, the first crystal structure of neutral thionicotinic acid is also reported, and showed the molecule to be in the form of the thione tautomer. Additionally, the synthesized compounds were tested against T. brucei, the causative agent of Human African Sleeping Sickness. Screening at 50 µM concentration showed that five of the compounds strongly inhibited growth and killed parasites. 相似文献
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Brent L. Kleintop Richard A. Yost Craig R. Abolin 《Journal of the American Society for Mass Spectrometry》1992,3(1):85-88
A new ion trap scan function for gas chromatography/mass spectrometry (GC/MS) quantitation is described that employs alternating mass-selective storage (rf/dc isolation) of ions from an analyte and its coeluting isotopically labeled internal standard. This scan includes two separate ionization/isolation/mass analysis sequences within the same scan function, each optimized for either the analyte or the internal standard. This results in alternating between analyzing the analyte and the internal standard during their coelution. The method is conceptually similar to using two different scan functions to analyze either the analyte or the internal standard in alternating scans; however, it is much faster because it eliminates the slow procedure of continuously downloading alternating scan functions from disk. This allows more data points to be obtained over a GC peak, resulting in more reproducible GC peak profiles as well as better sensitivity and precision. Results of calibration curves spanning four orders of magnitude (0.5 pg to 5 pg injected on column) obtained by using this method give excellent linear correlations (r 2 > 0.9990) and precision (relative standard deviations of triplicate injections < 10%). 相似文献
59.
A training set of 27 norstatine derived inhibitors of HIV-1 protease, based on the 3(S)-amino-2(S)-hydroxyl-4-phenylbutanoic acid core (AHPBA), for which the -log IC(50) values were measured, was used to construct 4D-QSAR models. Five unique RI-4D-QSAR models, from two different alignments, were identified (q(2) = 0.86-0.95). These five models were used to map the atom type morphology of the lining of the inhibitor binding site at the HIV protease receptor site as well as predict the inhibition potencies of seven test set compounds for model validation. The five models, overall, predict the -log IC(50) activity values for the test set compounds in a manner consistent with their q(2) values. The models also correctly identify the hydrophobic nature of the HIV protease receptor site, and inferences are made as to further structural modifications to improve the potency of the AHPBA inhibitors of HIV protease. The finding of five unique, and nearly statistically equivalent, RI-4D-QSAR models for the training set demonstrates that there can be more than one way to fit structure-activity data even within a given QSAR methodology. This set of unique, equally good individual models is referred to as the manifold model. 相似文献
60.
A method using capillary electrophoresis-mass spectrometry (CE-MS) was developed for the structural elucidation of bupivacaine and metabolites in rat urine. Prior to CE-MS analysis, solid-phase extraction (SPE) was used for sample cleanup and preconcentration purposes. Exact mass and tandem mass spectrometric (MS/MS) experiments were performed to obtain structural information about the unknown metabolites. Two instruments with different mass analyzers were used for mass spectrometric detection. A quadrupole time-of-flight (Q-TOF) and a magnetic sector hybrid instrument were coupled to CE and used for the analysis of urine extracts. Hydroxybupivacaine as well as five other isomerically different metabolites were detected including methoxylated bupivacaine. 相似文献