排序方式: 共有85条查询结果,搜索用时 15 毫秒
31.
Pratt HD Rose AJ Staiger CL Ingersoll D Anderson TM 《Dalton transactions (Cambridge, England : 2003)》2011,40(43):11396-11401
Copper-, manganese-, and zinc-based ionic liquids (Cu{NH(2)CH(2)CH(2)OH}(6)[CH(3)(CH(2))(3)CH(C(2)H(5))CO(2)](2) (2), Cu{NH(CH(2)CH(2)OH)(2)}(6)[CH(3)(CH(2))(3)CH(C(2)H(5))CO(2)](2) (3A), Cu{NH(CH(2)CH(2)OH)(2)}(6)[CF(3)SO(3)](2) (3B), Cu{NH(CH(2)CH(2)OH)(2)}(6)[(CF(3)SO(2))(2)N](2) (3C), Mn{NH(CH(2)CH(2)OH)(2)}(6)[CF(3)SO(3)](2) (4), and Zn{NH(2)CH(2)CH(2)OH}(6)[CF(3)SO(3)](2) (5)) are synthesized in a single-step reaction. Infrared data suggest that ethanolamine preferentially coordinates to the metal center through the amine group in 2 and the hydroxyl group in 5. In addition, diethanolamine coordinates through the amine group in 3A, 3C, and 4 and the hydroxyl group in 3B. The compounds are viscous (>1000 cP) at room temperature, but two (3C and 4) display specific conductivities that are reasonably high for ionic liquids (>20 mS cm(-1)). All of the compounds display a glass transition (T(g)) below -50 °C. The cyclic voltammograms (CVs) of 2, 3A, 3B, and 3C display a single quasi-reversible wave associated with Cu(II)/Cu(I) reduction and re-oxidation while 5 shows a wave attributed to Zn(II)/Zn(0) reduction and stripping (re-oxidation). Compound 4 is the first in this new family of transition metal-based ionic liquids (MetILs) to display reversible Mn(II)/Mn(III) oxidation and re-reduction at 50 mV s(-1) using a glassy carbon working electrode. 相似文献
32.
Back JH Zhu Y Calabro A Queenan C Kim AS Arbesman J Kim AL 《Photochemistry and photobiology》2012,88(5):1165-1172
Macroautophagy is a cellular response to various environmental stresses that ensures lysosomal degradation of long-lived and damaged proteins and cellular organelles. It occurs through the formation of an autophagosome, which then fuses with a lysosome to form an autolysosome. Depending on the cellular context, autophagy may promote cancer cell survival or it may serve as a mechanism of tumor suppression. Herein, we show that resveratrol, a natural phytoalexin, induces premature senescence in human A431 SCC cells, and that resveratrol-induced premature senescence is associated with a blockade of autolysosome formation, as assessed by the absence of colocalization of LC3 and Lamp-2, markers for autophagosomes and lysosomes, respectively. Further, we show that resveratrol downregulates the level of Rictor, a component of mTORC2, leading to decreased RhoA-GTPase and altered actin cytoskeleton organization. Exogenous overexpression of Rictor restores RhoA-GTPase activity and actin cytoskeleton network, and decreases resveratrol-induced senescence-associated β-gal activity, indicating a direct role of Rictor in senescence induction. Rictor is overexpressed in UV-induced murine SCCs, whereas its expression is diminished by oral administration of resveratrol. These data indicate that resveratrol attenuates autophagic process via Rictor, and suggest that downregulation of Rictor may be a mechanism of tumor suppression associated with premature senescence. 相似文献
33.
Goldberg JM Wissner RF Klein AM Petersson EJ 《Chemical communications (Cambridge, England)》2012,48(10):1550-1552
Thioamides quench tryptophan and tyrosine fluorescence in a distance-dependent manner and thus can be used to monitor the binding of thioamide-containing peptides to proteins. Since thioamide analogs of the natural amino acids can be synthetically incorporated into peptides, they can function as minimally-perturbing probes of protein/peptide interactions. 相似文献
34.
Christina L. Dugan George Glenn Peterson Alyssa Mock Christopher Young J. Matthew Mann Michael Nastasi Mathias Schubert Lu Wang Wai-Ning Mei Iori Tanabe Peter A. Dowben James Petrosky 《The European Physical Journal B - Condensed Matter and Complex Systems》2018,91(4):67
The semiconductor and optical properties of UO2 are investigated. The very long drift carrier lifetimes, obtained from current–voltage I(V) and capacitance–voltage C(V) measurements, along with the well-defined optical properties provide little evidence of an abundance of material defects away from the surface region. Schottky barrier formation may be possible, but very much dependent on the choice of contact and surface stoichiometry and we find that Ohmic contacts are in fact favored. Depth resolved photoemission provided evidence of a chemical shift at the surface. Density functional theory, with the Heyd-Scuseria-Ernzerhof (HSE) functional, indicates a band gap of a 2.19 eV and an anti-ferromagnetic ground state. Ellipsometry measurements indicates at UO2 is relatively isotropic with a band gap of approximately 2.0 eV band gap, consistent with theoretical expectations. 相似文献
35.
Manipatruni S Dokania RK Schmidt B Sherwood-Droz N Poitras CB Apsel AB Lipson M 《Optics letters》2008,33(19):2185-2187
We demonstrate high bit rate electro-optic modulation in a resonant micrometer-scale silicon modulator over an ambient temperature range of 15 K. We show that low bit error rates can be achieved by varying the bias current through the device to thermally counteract the ambient temperature changes. Robustness in the presence of thermal variations can enable a wide variety of applications for dense on chip electronic photonic integration. 相似文献
36.
Purple and blue wheats contain anthocyanins in the outer layers of the wheat kernel, and therefore purple and blue wholemeals can be a source of anthocyanins when developing processed cereal products. However, cereal processing is anticipated to cause significant anthocyanin losses. In this study, the anthocyanin content of crackers and bread made from one purple and three blue wholemeals was measured during processing and after baking. LC-MS/MS was used to confirm the presence of anthocyanins, and to tentatively identify them. Mixing and baking steps significantly decreased the anthocyanin content, whereas resting and fermentation steps did not. Purple and blue wholemeal samples reacted differently, indicating that the starting anthocyanin content, localization and composition may have some impact on anthocyanin retention. Additionally, dough systems with decreased pH were more protective of anthocyanins during intermediate processing steps, as were high-temperature, short-time baking procedures. This research provides insights into the processing steps that cause significant anthocyanin losses, and proposes some modifications to formulation and processing conditions which can further reduce losses. 相似文献
37.
A concise, 5-step synthesis of the hepatoprotective lactone MH-031 was achieved. Our approach utilizes several catalytic processes, namely, a Rauhut–Currier reaction, a chemoselective Fisher esterification, and a ring closing metathesis. Further elaboration of this lactone yielded the hydrazide natural product geralcin A and dihydrogeralcin B, a saturated analog of geralcin B. Biological evaluation of the latter indicated that the presence of the enehydrazide moiety in geralcin B is critical for anticancer activity. 相似文献
38.
Charles D. Baumgarner Alyssa H. Malen Stephen D. Pastor M. Ali NabiRahni 《Helvetica chimica acta》1992,75(2):480-486
The reaction of 9-bromoanthracene ( 1 ) with benzenethiol(ate) in tetraglyme proceeds by a SNAr mechanism. The concurrent formation of anthracene is not due to a competing single-electron-transfer pathway involving either benzenethiol or benzenethiolate anion. 相似文献
39.
Adam J. Pearce Alyssa A. Cassabaum Grace E. Gast Prof. Dr. Renee R. Frontiera Prof. Dr. Ian A. Tonks 《Angewandte Chemie (International ed. in English)》2016,55(42):13169-13173
The synthesis of the first terminal Group 9 hydrazido(2‐) complex, Cp*IrN(TMP) ( 6 ) (TMP=2,2,6,6‐tetramethylpiperidine) is reported. Electronic structure and X‐ray diffraction analysis indicate that this complex contains an Ir?N triple bond, similar to Bergman's seminal Cp*Ir(NtBu) imido complex. However, in sharp contrast to Bergman's imido, 6 displays remarkable redox non‐innocent reactivity owing to the presence of the Nβ lone pair. Treatment of 6 with MeI results in electron transfer from Nβ to Ir prior to oxidative addition of MeI to the iridium center. This behavior opens the possibility of carrying out facile oxidative reactions at a formally IrIII metal center through a hydrazido(2?)/isodiazene valence tautomerization. 相似文献
40.
Paolo Benigni Rebecca Marin Juan Camilo Molano-Arevalo Alyssa Garabedian Jeremy J. Wolff Mark E. Ridgeway Melvin A. Park Francisco Fernandez-Lima 《International Journal for Ion Mobility Spectrometry》2016,19(2-3):95-104
In the present work, we demonstrate the potential and versatility of TIMS for the analysis of proteins, DNA-protein complexes and protein-protein complexes in their native and denatured states. In addition, we show that accurate CCS measurement are possible using internal and external mobility calibration and in good agreement with previously reported CCS values using other IMS analyzers (<5 % difference). The main challenges for the TIMS-MS analysis of high mass proteins and protein complexes in the mobility and m/z domain are described. That is, the analysis of high molecular weight systems in their native state may require the use of higher electric fields or a small compromise in the TIMS mobility resolution by reducing the bath gas velocity in order to effectively trap at lower electric fields. This is the first report of CCS measurements of high molecular weight biomolecules and biomolecular complexes (~150 kDa) using TIMS-MS. 相似文献