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211.
Thiol-ene 'click' reactions have been initiated for a range of primary alkenes using ultrasound in both toluene and water. The method is particularly effective in aqueous solutions in the presence of air. 相似文献
212.
AE Goode JM Perkins A Sandison C Karunakaran H Cheng D Wall JA Skinner AJ Hart AE Porter DW McComb MP Ryan 《Chemical communications (Cambridge, England)》2012,48(67):8335-8337
Spectromicroscopy of tissue surrounding failed CoCr metal-on-metal hip replacements detected corroded nanoscale debris in periprosthetic tissue in two chemical states, with concomitant mitochondrial damage. The majority of debris contained Cr(3+), with trace amounts of oxidised cobalt. A minority phase containing a core of metallic chromium and cobalt was also observed. 相似文献
213.
This short communication describes features of UV-transparent capillaries employed for CEC and CE. A waveguide effect was observed when using UV-transparent capillaries. Through imaging with SEM, the UV-transparent coating was found to be highly porous unlike polyimide coating, which did not exhibit any porosity at all. Prolonged exposure to several commonly employed solvents with elevated pH caused abrasion of the coating at the capillary tip but no swelling of the UV-transparent coating was observed. Lastly, four different cutting techniques were compared to obtain smooth capillary tips. 相似文献
214.
Li S Schmidt JR Piryatinski A Lawrence CP Skinner JL 《The journal of physical chemistry. B》2006,110(38):18933-18938
Vibrational spectral diffusion denotes the time-dependent fluctuations of a solute's vibrational frequencies due to local environmental dynamics. Vibrational line shapes are weakly sensitive to spectral diffusion, whereas three-pulse vibrational echoes are much more sensitive. We report here on theoretical studies of spectral diffusion of the asymmetric stretch of the azide anion in heavy water. We run a classical molecular dynamics simulation of rigid azide in rigid water, and at every time step we calculate the azide's anharmonic asymmetric stretch frequency using an optimized quantum mechanics/molecular mechanics method developed earlier. This generates a frequency trajectory, which we use to calculate the absorption line shape and integrated three-pulse echo intensity. Our results for both the line width and the integrated echo intensity are in excellent agreement with experiment. Our calculated frequency time-correlation function is in excellent agreement with experiment for long times (greater than 250 fs) but differs considerably from experiment at short times; our theoretical correlation function has a very pronounced oscillation, presumably due to intermolecular azide-water hydrogen-bond stretching dynamics. 相似文献
215.
Accurate high energy x-ray diffraction data are presented on liquid water measured at room temperature. Sources of both systematic and statistical errors within the experiment are considered and data consistency checks are discussed. It is found that the resulting x-ray pair distribution function is smoothly varying in real space and shows no evidence of small peaks in the 3-5???region. Our results are in contrast to the recent findings reported in Petkov et al 2012 J. Phys.: Condens. Matter 24 155102. 相似文献
216.
Erik M. Muller John Smedley Jen Bohon Xi Yang Mengjia Gaowei John Skinner Gianluigi De Geronimo Michael Sullivan Marc Allaire Jeffrey W. Keister Lonny Berman Annie Héroux 《Journal of synchrotron radiation》2012,19(3):381-387
Two transmission‐mode diamond X‐ray beam position monitors installed at National Synchrotron Light Source (NSLS) beamline X25 are described. Each diamond beam position monitor is constructed around two horizontally tiled electronic‐grade (p.p.b. nitrogen impurity) single‐crystal (001) CVD synthetic diamonds. The position, angle and flux of the white X‐ray beam can be monitored in real time with a position resolution of 500 nm in the horizontal direction and 100 nm in the vertical direction for a 3 mm × 1 mm beam. The first diamond beam position monitor has been in operation in the white beam for more than one year without any observable degradation in performance. The installation of a second, more compact, diamond beam position monitor followed about six months later, adding the ability to measure the angular trajectory of the photon beam. 相似文献
217.