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Inside Cover: Synthesis,Characterization, and Theoretical Investigation of Two‐Coordinate Palladium(0) and Platinum(0) Complexes Utilizing π‐Accepting Carbenes (Chem. Eur. J. 26/2015) 下载免费PDF全文
Dr. Sudipta Roy Dr. Kartik Chandra Mondal Dipl.‐Chem. Jann Meyer Dipl.‐Chem. Benedikt Niepötter Christian Köhler Dr. Regine Herbst‐Irmer Prof. Dr. Dietmar Stalke Dr. Birger Dittrich Dr. Diego M. Andrada Prof. Dr. Gernot Frenking Prof. Dr. Herbert W. Roesky 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(26):9266-9266
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Kartik Arora Radhakrishna Sureshkumar Matthew P. Scheiner Justin L. Piper 《Rheologica Acta》2002,41(1-2):25-34
We employ digital particle imaging velocimetry (DPIV) to investigate the influence of a drag reducing cationic surfactant
additive, cetyltrimethyl-ammonium chloride (CTAC), on turbulent swirling flows generated in a cylindrical vessel either by
a rotating disk or a rotating disk fitted with vertical flat blades. The largest concentration of CTAC used in this study
(0.05 ≤ C ≤ 0.5 mmol/l) is an order of magnitude smaller than those used in experimental investigations of surfactant induced
drag reduction in turbulent pipe/channel flows. Even for such dilute systems, a number of dramatic and intriguing effects
are observed. In the case of disk-driven flow, it is shown that the surfactant has a non-monotonic influence on turbulence
intensity: both radial and axial root mean square velocity fluctuations first increase with increasing surfactant concentration
C, reach a maximum and decrease upon further increase in C. Moreover, the maximum intensity is attained at a concentration
that is practically independent of the angular frequency Ω of the disk. For the flow driven by bladed impeller, the introduction
of the surfactant leads to flow reversal at the impeller plane for low concentrations. Enhancement in the radial and azimuthal
mean velocities is also observed. For relatively larger concentrations (=0.5 mmol/l), a mean flow field that consists of multiple
transient mixing pockets emerges as Ω exceeds a critical value. Plausible mechanisms are proposed to explain these observations.
Received: 11 September 2000 Accepted: 10 April 2001 相似文献
64.
John T. Gupton Robert B. Miller Stuart C. Clough Rene P.F. Kanters Kartik M. Keertikar John M. Solano Daniel W. Callahan Austin B. Scharf 《Tetrahedron》2005,61(7):1845-1854
A new and efficient relay synthesis of the marine natural products polycitone A and B is described. The new strategy relies on the formation of 2,4-disubstituted pyrroles from a vinamidinium salt followed by electrophilic substitution at the 5-position of the pyrrole and Suzuki coupling at the 4-position to produce the tetrasubstituted heterocycle efficiently and with complete control of regiochemistry. 相似文献
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Kartik S Crittenden R De K Dzierba A Li R Markham S Marshall T Martin J Smith P Sulanke T Welch K Zieminski A Gomez R Krider J Goldberg H Margulies S Solomon J Davis C Dauwe L Abramov V Antipov Y Baldin B Denisov S Glebov V Gorin Y Koreshev V Petrukhin A Sirotenko V Sulyaev R 《Physical review D: Particles and fields》1990,41(1):1-8
66.
Far-field measurements of the in-plane polarization properties of spontaneous emission from optical nanocavities formed in two-dimensional photonic crystal slab waveguides are presented. A strong polarization signature, even subthreshold, is found for a pair of highly localized dipolelike resonant modes. This polarization signature is used to study the effects of symmetry lowering within the cavity. 相似文献
67.
The efficiency of evanescent coupling between a silica optical fiber taper and a silicon photonic crystal waveguide is studied. A high-reflectivity mirror on the end of the photonic crystal waveguide is used to recollect, in the backward-propagating fiber mode, the optical power that is initially coupled into the photonic crystal waveguide. An outcoupled power in the backward-propagating fiber mode of 88% of the input power is measured, corresponding to a lower bound on the coupler efficiency of 94%. 相似文献
68.
Ekta Nag Sridhar Battuluri Dr. Kartik Chandra Mondal Dr. Sudipta Roy 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(64):e202202324
Silver clusters are attractive candidates for their promising optical properties, and biomedical activities. Herein, we report on the first syntheses and isolation of three homo-/mixed-valence silver nanoclusters (NCs) with Ag12Cl3, Ag29, and Ag8 cores [((cAAC)P)6Ag12Cl3](OTf)3 ( 1 ), [((cAAC)P)6Ag29] ( 2 ), and [((cAAC)P)4Ag8] ( 3 ) having three-/twofold symmetry, employing cyclic alkyl(amino) carbene (cAAC)-supported phosphinidenide (cAACP−) as the π-accepting stabilizing ligand. The average diameters of Ag NCs 1 , and 2 are approximately 1.6 to 2 nm. The redox non-innocent mono-atomic phosphorus anions (P−) anchored with cAAC ligands are generated in situ by the reaction of AgOTf with a boryl-phosphaalkene (cAAC)P−B(NiPr2)2 through cleavage of the P−B bond with the help of a triflate anion (OTf−) as a weak nucleophile. Equivalent number of the (cAAC)P− anions generated in situ are oxidized to produce the corresponding bis-phosphinidene (cAAC)2P2 leading to the generation of Ag0 ions in solution for the formation of the unprecedented mixed-valence Ag NC 2 . Complex 3 is achieved by treating potassium phosphinidenide cAACPK with AgNTf2. The ligand field and the steric hindrance of the (cAAC)P units play crucial roles in stabilizing complexes 1 – 3 , further providing a three- ( 1 , 2 )/two- ( 3 ) fold stand. The Ag12Cl3 NC ( 1 ) with a tricationic core [AgI12Cl3] was found to be diamagnetic, and fluorescent, emitting green light at 563 nm when excited at 400 nm. In contrast, the neutral Ag29 ( 2 ) and Ag8 ( 3 ) clusters were found to be paramagnetic, and NMR silent showing characteristic EPR signals for Ag0 at room temperature. 相似文献
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Formulations of traditional medicines are usually made up of a complex mixture of herbs. However, effective quality control methods in order to select materials of the right quality are lacking. 'Amukkara choornam' is a polyherbal Siddha formulation used for gastritis, spleen enlargement, leucorrhoea, hiccups, anaemia, tuberculosis and kappa diseases. Trans-caryophyllene is an important constituent present in the ingredients of this formulation. In a literature survey, it was found that there is no such method for the quantification of trans-caryophyllene except gas chromatography or gas chromatography-mass spectroscopy (GC-MS). So, a high performance thin layer chromatography (HPTLC) method was developed and validated for the quantification of trans-caryophyllene in amukkara choornam. Pre-coated silica gel 60F-254 plates (10 × 10 cm2) were used for the analysis. The solvent system consisted of toluene-ethyl acetatate (9 : 3, v/v), and trans-caryophyllene was detected at 260 nm. The developed method was validated for linearity (R2 = 0.9996 ± 0.0034), limit of detection (LOD) (0.101 ng), limit of quantification (LOQ) (0.639 ng), accuracy (% recovery = 97.19 ± 1.204), and precision (CV < 5%, for both intra-day and inter-day precisions). The levels of trans-caryophyllene were found to be 3.5-4.10 μg per gram of herbal products. 相似文献
70.
Hybrid quantum information devices that combine disparate physical systems interacting through photons offer the promise of combining low-loss telecommunications wavelength transmission with high fidelity visible wavelength storage and manipulation. The realization of such systems requires control over the waveform of single photons to achieve spectral and temporal matching. Here, we experimentally demonstrate the simultaneous wavelength translation and amplitude modulation of single photons generated by a quantum dot emitting near 1300 nm with an exponentially decaying waveform (lifetime ≈1.5 ns). Quasi-phase-matched sum-frequency generation with a pulsed 1550 nm laser creates single photons at 710 nm with a controlled amplitude modulation at 350 ps time scales. 相似文献