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91.
Ostergaard J Jorgensen L Engelbrecht Thomsen A Weng Larsen S Larsen C Jensen H 《Electrophoresis》2008,29(16):3320-3324
The potential of using CE frontal analysis (CE-FA) for the study of low-molecular-weight drug-liposome interactions was assessed. The interaction of bupivacaine, brompheniramine, chlorpromazine, imipramine, and ropivacaine with net negatively charged 80/20 mol% 1-oleoyl-2-palmitoyl-sn-glycero-3-phosphocholine/egg yolk phosphatidic acid liposome suspensions in HEPES buffer at pH 7.4 was investigated. The fraction of free drug as a function of lipid concentration was measured and apparent liposome - buffer distribution coefficients were determined for the basic drug substances. The distribution coefficients increased in the order ropivacaine, bupivacaine, brompheniramine, imipramine, and chlorpromazine. The developed CE method was relatively fast allowing estimates of drug-liposome affinity to be obtained within 15 min. CE-FA may have the potential to become a valuable tool for the characterization of drug-liposome interactions in relation to estimation of drug lipophilicity and for the evaluation of drug distribution in liposomal drug delivery systems. 相似文献
92.
93.
Melanie Heghmanns Andreas Rutz Yury Kutin Vera Engelbrecht Martin Winkler Thomas Happe Müge Kasanmascheff 《Chemical science》2022,13(29):8704
Correction for ‘The oxygen-resistant [FeFe]-hydrogenase CbA5H harbors an unknown radical signal’ by Melanie Heghmanns et al., Chem. Sci., 2022, 13, 7289–7294, https://doi.org/10.1039/D2SC00385F.The authors realized that incorrect references were cited following the sentence “In conjunction with the signal''s significant width, the frequency dependence clearly indicates spin–spin interaction between the F-clusters.” The correct references are shown below as ref. 1 and 2.Additionally ref. 36 and 37 were reversed in the reference list. The correct ref. 36 is shown below as ref. 3 and the correct ref. 37 is shown below as ref. 4.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers. 相似文献
94.
In the reaction of CF3SOCl with NaN3 or (CH3)3SiN3, azide, CF3SON3 (I) is formed: Upon gentle warming to room temperature, (I) decomposes under evolution of N2 to give CF3SON (II), which however oligomerizes instantaneously, The monomeric nitride(II) can be captured in the presence of reactive halogene compounds to yield N-substituted trifluoromethan-imino sulfonyl chlorides. With CH3CN, a six-membered ring compound is obtained: 相似文献
95.
96.
Research in the late 1940s in academic institutions, most notably the University of Hull in the UK, led to the development of liquid crystal display technology in the 1970s, which has subsequently had a large impact throughout the world. The liquid crystal technology is based on simple organic molecules. Since the late 1980s, some liquid crystal scientists have turned their attention to investigating the effect of introducing a metal atom into the systems. This review focuses on the major developments in the field of ferrocenyl‐containing liquid crystals in which the organometallic group is situated in a terminal position with respect to the core of the molecule. Metallomesogens with terminal metal atoms are not very common, since it can be deduced from the theory of organic liquid crystals that bulky terminal groups would not be conducive to the stabilization of liquid crystal phases. Nevertheless, a terminal ferrocenyl group can stabilize a nematic liquid crystal phase and examples of this will be discussed in this review. Copyright © 2001 John Wiley & Sons Ltd. 相似文献
97.
The dispersion of nonlinear waves in a relaxing medium is analysed by making use of the evolution equations for longitudinal waves. The dispersion relations are obtained and the behaviour of the waves compared to those that arise when they are governed by the well-known Korteweg-de Vries (KdV) and Benjamin-Bona-Mahony (BBM) equations that describe unidirectional motion and also by the time regularized long wave (TRLW) equation that describes bi-directional motion. The nonlinear steady wave solutions are obtained. The general mathematical model used throughout this paper is obtained by the theory of nonlinear elasticity with weak relaxation effects (standard viscoelasticity). A further generalization using a four-element model is also discussed briefly. 相似文献
98.
99.
Melanie Heghmanns Andreas Rutz Yury Kutin Vera Engelbrecht Martin Winkler Thomas Happe Müge Kasanmascheff 《Chemical science》2022,13(24):7289
[FeFe]-hydrogenases catalyze the reversible conversion of molecular hydrogen into protons and electrons with remarkable efficiency. However, their industrial applications are limited by their oxygen sensitivity. Recently, it was shown that the [FeFe]-hydrogenase from Clostridium beijerinckii (CbA5H) is oxygen-resistant and can be reactivated after oxygen exposure. In this work, we used multifrequency continuous wave and pulsed electron paramagnetic resonance (EPR) spectroscopy to characterize the active center of CbA5H, the H-cluster. Under oxidizing conditions, the spectra were dominated by an additional and unprecedented radical species. The generation of this radical signal depends on the presence of an intact H-cluster and a complete proton transfer pathway including the bridging azadithiolate ligand. Selective 57Fe enrichment combined with isotope-sensitive electron-nuclear double resonance (ENDOR) spectroscopy revealed a spin density distribution that resembles an H-cluster state. Overall, we uncovered a radical species in CbA5H that is potentially involved in the redox sensing of CbA5H.Electron paramagnetic resonance spectroscopy revealed an unprecedented radical species in the oxygen-resistant [FeFe]-hydrogenase CbA5H. Analysis of the isotope-sensitive data suggests that it is related to the active site, the H-cluster. 相似文献
100.
We present a tunable diode laser spectrometer that can be software-switched between a wavelength modulation spectroscopy (WMS)
operation mode and the direct absorption spectroscopy (DAS) technique on a per-scan basis. The new setup allows a direct comparison
between the two techniques under equal hardware and system environment conditions. In this work, we compare the impact of
analog-to-digital converter resolution for operation in WMS and DAS mode. Example concentration evaluations show that in the
DAS approach, relative absorptions smaller than the least significant bit can be measured with scan averaging and FIR-filtering
applied. With full resolution, both techniques show similar performance in our setup, with a slight advantage for the WMS
implementation. 相似文献