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11.
Aubert B Boutigny D Gaillard JM Hicheur A Karyotakis Y Lees JP Robbe P Tisserand V Palano A Pompili A Chen GP Chen JC Qi ND Rong G Wang P Zhu YS Eigen G Stugu B Abrams GS Borgland AW Breon AB Brown DN Button-Shafer J Cahn RN Clark AR Gill MS Gritsan AV Groysman Y Jacobsen RG Kadel RW Kadyk J Kerth LT Kolomensky YG Kral JF LeClerc C Levi ME Lynch G Oddone PJ Pripstein M Roe NA Romosan A Ronan MT Shelkov VG Telnov AV Wenzel WA Harrison TJ Hawkes CM Knowles DJ O'Neale SW Penny RC Watson AT 《Physical review letters》2002,88(22):221802
Flavor oscillations of neutral B mesons have been studied in e+e- annihilation data collected with the BABAR detector at center-of-mass energies near the upsilon(4S) resonance. The data sample used for this purpose consists of events in which one B0 meson is reconstructed in a hadronic decay mode, while the flavor of the recoiling B0 is determined with a tagging algorithm that exploits the correlation between the flavor of the heavy quark and the charges of its decay products. From the time development of the observed mixed and unmixed final states, we determine the B0-B-0 oscillation frequency deltamd to be 0.516+/-0.016(stat)+/-0.010(syst) ps-1. 相似文献
12.
The surface and adsorbate chemistry of the TiO2(100) surface prepared at high temperatures and ambient conditions were studied by means of angle resolved X-ray photoelectron spectroscopy (AR-XPS), Low Energy Electron Diffraction (LEED) and Atomic Force Microscopy (AFM) based nanoshaving studies. The TiO2(100) surface shows a 1 × 1 structure with a 1 × 3 superstructure assigned to surface defects. A significant hydroxide surface concentration was revealed by means of AR-XPS measurements. The adsorbate formation of nonadecanoic acid (NDCA) from ethanolic solution led to disordered sub-monolayer surface coverage. The weak interaction between the carboxylic acid group and the TiO2 surface is assumed to be a combination of the neutral to acid behavior of the TiO2 surface and the stable hydroxide surface layer created under ambient conditions. 相似文献
13.
U. Kunze R. Burghardt 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2-4):373-376
Abstract The methylester hydrochlorides of the (S)-amino acids L-alanine (la), L-phenylalanine (1b), L-valine (1c) and L-lysine (1d) were converted to the corresponding isothiocyanates 2a-d by thiophosgenation. 2a-d react with secondary phosphines and phosphine oxides to give the thiocarbamoylphosphines 3a-d and P-oxides 4a, b. 相似文献
14.
Silicone breast implants are used for breast augmentation and breast reconstruction. The issues of concern associated with such implants are: (a) the quality control of each implant before implantation, and (b) the detection of implant bleeding after implantation. We have studied the use of the Nuclear Magnetic Resonance-MObile Universal Surface Explorer (NMR-MOUSE) for the nondestructive testing of (a) the quality of implant shells, and (b) changes in implant gel due to leakage of body fluid into the implant. Depth profiles measured nondestructively through implant shells at different positions of each implant by the Profile NMR-MOUSE assured good reproducibility of the quality and thickness of different shell layers. The leakage of implants upon rupture was mimicked by observing changes in the transverse NMR relaxation time of the implant gel upon ingress of physiological saline solution and safflower oil through the rupture. Results demonstrate that nondestructive testing with unilateral NMR is a potential method for use in the quality control of implants and for the screening of implants for rupture after implantation. 相似文献
15.
Measurements of the first Townsend coefficient for the vapours of CH3OH, C2H5OH, C3H7OH(n), C3H7OH(iso) are described. The experimental arrangement is tested by measuring the known values of air and argon. 相似文献
16.
A series of new tetracarbonyl and tricarbonyl complexes of manganese and rhenium with heteroallylic phosphine chelate ligands L [XC(Y)PPh2]? and HXC-(Y)PPh2 (X, Y NR, O, S) were prepared by reaction of the appropriate metal carbonyl halides with the free ligands or their silyl intermediates. The silyl method yields both cis-(CO)4ML and fac-(CO)3M(X)L (X Cl, Br) complexes by controlled addition of water. Analytical, spectroscopic and crystallographic data of the ambidentate thioformamide ligands result in a P,S-coordination in all complexes. The 13C NMR spectra of several selected compounds were recorded and reveal some unexpected features. 相似文献
17.
Dr. Nicolai Wagner Milena Schuhmacher Annett Lohmann Dr. André Nadler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(68):15483-15487
Photorelease of caged compounds is among the most powerful experimental approaches for studying cellular functions on fast timescales. However, its full potential has yet to be exploited, as the number of caged small molecules available for cell biological studies has been limited by synthetic challenges. Addressing this problem, a straightforward, one-step procedure for efficiently synthesizing caged compounds was developed. An in situ generated benzylic coumarin triflate reagent was used to specifically functionalize carboxylate and phosphate moieties in the presence of free hydroxy groups, generating various caged lipid metabolites, including a number of GPCR ligands. By combining the photo-caged ligands with the respective receptors, an easily implementable experimental platform for the optical control and analysis of GPCR-mediated signal transduction in living cells was developed. Ultimately, the described synthetic strategy allows rapid generation of photo-caged small molecules and thus greatly facilitates the analysis of their biological roles in live cell microscopy assays. 相似文献
18.
Markus Bursch Lukas Kunze Dr. Amol M. Vibhute Dr. Andreas Hansen Prof. Dr. Kana M. Sureshan Dr. Peter G. Jones Prof. Dr. Stefan Grimme Prof. Dr. Daniel B. Werz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(14):4627-4639
The noncovalent interactions between azides and oxygen-containing moieties are investigated through a computational study based on experimental findings. The targeted synthesis of organic compounds with close intramolecular azide–oxygen contacts yielded six new representatives, for which X-ray structures were determined. Two of those compounds were investigated with respect to their potential conformations in the gas phase and a possible significantly shorter azide–oxygen contact. Furthermore, a set of 44 high-quality, gas-phase computational model systems with intermolecular azide–pnictogen (N, P, As, Sb), –chalcogen (O, S, Se, Te), and –halogen (F, Cl, Br, I) contacts are compiled and investigated through semiempirical quantum mechanical methods, density functional approximations, and wave function theory. A local energy decomposition (LED) analysis is applied to study the nature of the noncovalent interaction. The special role of electrostatic and London dispersion interactions is discussed in detail. London dispersion is identified as a dominant factor of the azide–donor interaction with mean London dispersion energy-interaction energy ratios of 1.3. Electrostatic contributions enhance the azide–donor coordination motif. The association energies range from −1.00 to −5.5 kcal mol−1. 相似文献
19.
20.
Peng S Ahlmann N Kunze K Nigge W Edler M Hoffmann T Franzke J 《Rapid communications in mass spectrometry : RCM》2004,18(16):1803-1808
The desorption of an analyte by a continuous wave diode laser from a porous surface of a thin-layer plate covered with a graphite suspension is presented. The thermally desorbed analyte molecules are ionized in the gas phase by a corona discharge at atmospheric pressure. Therefore, both essential processes--the desorption and the ionization of analyte molecules, which are often performed in one step--are separated. The target preparation is easy and fast since no additional extraction process is required. The mass spectrometric background signal was mostly limited to the low mass range showing no interference with typical compounds of interest. In this study, the calmative and antihypertensive drug reserpine was chosen as model analyte, which is often used for specification of mass spectrometers. No fragmentation was observed because of efficient collisional cooling under atmospheric pressure. The influence of diode laser power and the composition of the graphite suspension were investigated, and a primary optimization was performed. 相似文献