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Gregory J. S. Fowler Wim Crielaardt† Ronald W. Visschers Rienk van Grondelle C. Neil Hunter 《Photochemistry and photobiology》1993,57(1):2-5
The present study describes the construction of a Rhodobacter sphaeroides light-harvesting (LH2) mutant in which the charged residue βSLys23 is changed by site-directed mutagenesis to a Gin residue, and the characterization of the resulting mutant complex by a range of spectroscopic techniques. In the 77 K absorption spectrum of the mutant, the peak equivalent to the 850 nm peak in the wild-type membrane is blue-shifted by approximately 18 nm to 837 nm; except for this blue-shift, the 77 K. fluorescence excitation and emission spectra and the circular dichroism spectrum of the mutant are very similar to the equivalent spectra from the wild-type membranes, suggesting that the mutation βLys23 → Gin probably does not cause any major changes in the conformation or aggregation state of these membranes. Possible causes of the 18 nm blue-shift in the absorption spectrum are discussed. 相似文献
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We consider a memoryless single station service system with servers \(\mathcal{S}=\{m_{1},\ldots,m_{K}\}\), and with job types \(\mathcal{C}=\{a,b,\ldots\}\). Service is skill-based, so that server m i can serve a subset of job types \(\mathcal{C}(m_{i})\). Waiting jobs are served on a first-come-first-served basis, while arriving jobs that find several idle servers are assigned to a feasible server randomly. We show that there exist assignment probabilities under which the system has a product-form stationary distribution, and obtain explicit expressions for it. We also derive waiting time distributions in steady state. 相似文献
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Misiejuk A Papandreou Z Voutier E Bauer TS Blok HP Boersma DJ Den Bok HW Bruins EE Farzanpay F Grüner K Hesselink WH Huber GM Jans E Kalantar-Nayestanaki N Kasdorp WJ Konijn J Laget JM Lapikás L Lolos GJ Onderwater GJ Pellegrino A Schroevers R Spaltro CM Starink R van der Steenhoven G Steiger JJ Visschers JL Willering HW Yeomans DM 《Physical review letters》2002,89(17):172501
The differential cross section for electron-induced neutron knockout in the reaction 4He(e,e(')n)(3)He has been measured for the first time with a statistical accuracy of 11%. The experiment was performed in quasielastic kinematics at a momentum transfer of 300 MeV/c and in the missing-momentum range of 25-70 MeV/c. The comparison of the data with theoretical calculations shows an impressive increase of the cross section resulting from final state interaction effects. Specifically, the p-n charge-exchange process dominates the cross section in this kinematical regime. 相似文献
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Jungmann JH MacAleese L Buijs R Giskes F de Snaijer A Visser J Visschers J Vrakking MJ Heeren RM 《Journal of the American Society for Mass Spectrometry》2010,21(12):2023-2030
In mass spectrometry imaging, spatial resolution is pushed to its limits with the use of ion microscope mass spectrometric
imaging systems. An ion microscope magnifies and then projects the original spatial distribution of ions from a sample surface
onto a position-sensitive detector, while retaining time-of-flight mass separation capabilities. Here, a new type of position-sensitive
detector based on a chevron microchannel plate stack in combination with a 512 × 512 complementary metal-oxide-semiconductor
based pixel detector is coupled to an ion microscope. Spatial resolving power better than 6 μm is demonstrated by secondary
ion mass spectrometry and 8–10μm spatial resolving power is achieved with laser desorption ionization. A detailed evaluation
of key performance criteria such as spatial resolution, acquisition speed, and data handling is presented. 相似文献
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