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61.
Curtis P. Rinsland Steven W. Sharpe 《Journal of Quantitative Spectroscopy & Radiative Transfer》2005,96(2):271-280
Pressure broadened (1 atm. N2) absorption cross sections and integrated band intensities have been derived from laboratory spectra of CH3CN, recorded at 276, 298, and 323 K, covering 600-. The spectra were recorded at a resolution of using a commercial Fourier transform spectrometer and a custom flowing sample delivery system. We report integrated absorption cross sections for intervals corresponding to the most prominent bands, compare the results with previously reported values, and discuss error sources, which are estimated as ∼7% with systematic error the largest error source. 相似文献
62.
S. Eriksson F. Ramirez-Martinez E.A. Curtis B.E. Sauer P.W. Nutter E.W. Hill E.A. Hinds 《Applied physics. B, Lasers and optics》2004,79(7):811-816
We have produced magnetic patterns suitable for trapping and manipulating neutral atoms on a 1-m length scale. The required patterns are made in Co/Pt thin films on a silicon substrate, using the heat from a focused laser beam to induce controlled domain reversal. In this way we draw lines and paint shaped areas of reversed magnetisation with sub-micron resolution. These structures produce magnetic microtraps above the surface that are suitable for holding rubidium atoms with trap frequencies as high as 1 MHz. PACS 39.25.+k; 03.75.Be; 75.50.Ss; 75.70.-i 相似文献
63.
Berlinguette CP Dragulescu-Andrasi A Sieber A Galán-Mascarós JR Güdel HU Achim C Dunbar KR 《Journal of the American Chemical Society》2004,126(20):6222-6223
A charge-transfer-induced spin transition (CTIST) is observed in the discrete cyanide-bridged complex, {[Co(tmphen)2]3[Fe(CN)6]2}. Single-crystal X-ray diffraction, 57Fe M?ssbauer spectroscopy, and magnetic susceptibility were used collectively to describe the oxidation states of the Co and Fe ions in this cluster as a function of temperature. This pentanuclear complex represents the first example of a CTIST at the discrete molecular level. 相似文献
64.
Structure of optical vortices 总被引:1,自引:0,他引:1
Helical modes of light can be focused into toroidal optical traps known as optical vortices, which are capable of localizing and applying torques to small volumes of matter. Measurements of optical vortices created with the dynamic holographic optical tweezer technique reveal an unsuspected dependence of their structure and angular momentum flux on their helicity. These measurements also provide evidence for a novel optical ratchet potential in practical optical vortices. 相似文献
65.
Gallagher A Aduse-Opoku J Rangarajan M Slaney JM Curtis MA 《Current protein & peptide science》2003,4(6):427-441
Post-translational modification of proteins by covalent attachment of sugars to the protein backbone (protein glycosylation) is the most common post-translational modification in the eucaryotic cell. However, the addition of carbohydrates to proteins of Eubacteria and Archaea has been demonstrated and accepted only recently. There is now a rapidly expanding list of bacterial glycoproteins that have been characterised from a variety of different organisms including many important pathogens. The Arg-gingipains of Porphyromonas gingivalis are recent additions to this list. In this review we present a summary of our investigations on the structure of the glycan additions to these proteolytic enzymes, the genetics of the glycosylation process and some of the effects on enzyme function and recognition. These findings are placed in the context of the current status of understanding of glycoconjugate structure and synthesis in other bacteria. Given the importance of glycosylation of eucaryotic proteins to their stability, structure, resistance to proteolysis and recognition, the modifications to the proteases described in the present report are likely to have a functional role in the properties of these enzymes in periodontal disease. 相似文献
66.
Labiche M Orr NA Marqués FM Angélique JC Axelsson L Benoit B Bergmann UC Borge MJ Catford WN Chappell SP Clarke NM Costa G Curtis N D'Arrigo A de Góes Brennand E Dorvaux O Fazio G Freer M Fulton BR Giardina G Grévy S Guillemaud-Mueller D Hanappe F Heusch B Jones KL Jonson B Le Brun C Leenhardt S Lewitowicz M Lopez MJ Markenroth K Mueller AC Nilsson T Ninane A Nyman G de Oliveira F Piqueras I Riisager K Saint Laurent MG Sarazin F Singer SM Sorlin O Stuttgé L 《Physical review letters》2001,86(4):600-603
The two-neutron halo nucleus (14)Be has been investigated in a kinematically complete measurement of the fragments ((12)Be and neutrons) produced in dissociation at 35 MeV/nucleon on C and Pb targets. Two-neutron removal cross sections, neutron angular distributions, and invariant mass spectra were measured, and the contributions from electromagnetic dissociation (EMD) were deduced. Comparison with three-body model calculations suggests that the halo wave function contains a large nu(2s(1/2))(2) admixture. The EMD invariant mass spectrum exhibited enhanced strength near threshold consistent with a nonresonant soft-dipole excitation. 相似文献
67.
Improved short-term stability of optical frequency standards: approaching 1 Hz in 1 s with the Ca standard at 657 nm 总被引:2,自引:0,他引:2
For a neutral (40)Ca-based optical frequency standard we report a fractional frequency instability of 4 x 10(-15) in 1 s, which represents a fivefold improvement over existing atomic frequency standards. Using the technique of optical Bordé-Ramsey spectroscopy with a sample of 10(7) trapped atoms, we have resolved linewidths as narrow as 200 Hz (FWHM). With colder atoms this system could potentially achieve an instability as low as 2 x 10(-16) in 1 s. Such low instabilities are important for frequency standards and precision tests of fundamental physics. 相似文献
68.
69.
A semi-analytical streamline-based model, employing stratification and macro physics only, is developed and utilized to simulate
injection/production phases of single-well push–pull tests. Modeling results are compared with experimental field data, giving
an excellent match, without resorting to parameter fitting, simply by putting in known test-site properties, such as stratification
data, hydraulic head gradients, and test parameters. 相似文献
70.
Matthew Curtis Mikael A. Minier Priyanka Chitranshi O. David Sparkman Patrick R. Jones Liang Xue 《Journal of the American Society for Mass Spectrometry》2010,21(8):1371-1381
Direct analysis in real time (DART) mass spectrometry is a recently developed innovative technology, which has shown broad
applications for fast and convenient analysis of complex samples. Due to the ease of sample preparation, we have recently
initiated an investigation of the feasibility of detecting nucleotides and nucleosides using the DART-AccuTOF instrument,
which we will refer to as the DART mass spectrometer. Our experimental results reveal that the ions representing the intact
molecules of nucleotides are not detectable in either positive-ion or negative-ion mode. Instead, all four natural nucleotides
fragment in the DART ion source, and a common fragment ion, [C5H5O]+ (1), is observed, which is probably formed via multiple-elimination reactions. Interestingly, 1 can form adducts with nucleobases
in different molar ratios in the DART ion source. In contrast to nucleotides, the ions representing the intact molecules of
nucleosides are detected in both positive-ion and negative-ion mode using DART mass spectrometry. Surprisingly, the fragmentation
pattern of nucleosides is different from that of nucleotides in the DART ion source. In the cases of nucleosides (under positive-ion
conditions), the production of 1 is not observed, indicating that the phosphate group plays an important role for the multiple
eliminations observed in the spectra of nucleotides. The in-source reactions described in the present work show the complexity
of the conditions in the DART ion source, and we hope that our results illustrate a better understanding about DART mass spectrometry. 相似文献