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91.
A liquid chromatography (LC) method is described for the determination of oxytetracycline (OTC) in farmed Atlantic salmon muscle tissue. The method involves homogenization of salmon tissue, extraction of OTC into Mcllvaine-EDTA buffer, acid precipitation of proteins, cleanup through tandem solid-phase extraction cartridges (Strata-X and aminopropyl), elution with mobile phase containing slightly alkaline buffer and Mg2+, and LC separation with metal-chelate induced fluorescence detection. Salmon tissue was fortified with 0.10, 0.25, 0.50, 0.75, and 1.0 microg/g (ppm) oxytetracycline. Average absolute recoveries were 84, 76, 70, 76, and 85%, respectively, with relative standard deviation (RSD) values all less than 9%. The interassay average recovery was 78%, with a 4.2% RSD. Determination was based on a standard graph using peak areas with standard solutions equivalent to 0.0625, 0.125, 0.25, 0.50, and 1.0 ppm in tissue. A set of 5 matrix controls (unfortified salmon tissue) were also analyzed, in which no OTC was detected. The lowest standard was used as the limit of quantitation. 相似文献
92.
Caligiuri M Becker F Murthi K Kaplan F Dedier S Kaufmann C Machl A Zybarth G Richard J Bockovich N Kluge A Kley N 《Chemistry & biology》2005,12(10):1103-1115
The identification of molecular determinants of tumor cell survival is an important objective in cancer research. Here, we describe a small-molecule kinase inhibitor (RGB-286147), which, besides inhibiting tumor cell cycle progression, exhibits potent cytotoxic activity toward noncycling tumor cells, but not nontransformed quiescent fibroblasts. Extensive yeast three-hybrid (Y3H)-based proteome/kinome scanning with chemical dimerizers revealed CDK1/2/3/5/7/9 and the less well-characterized CDK-related kinases (CRKs) p42/CCRK, PCTK1/3, and PFTK1 as its predominant targets. Thus, RGB-286147 is a proteome-wide CDK/CRK-specific kinase inhibitor whose further study could yield new insight into molecular determinants of tumor cell survival. Our results also suggest that the [1, 3, 6]-tri-substituted-pyrazolo[3,4-d]-pyrimidine-4-one kinase inhibitor scaffold is a promising template for the rational design of kinase inhibitors with potential applications to disease indications other than cancer, such as neurodegeneration, cardiac hypertrophic growth, and AIDS. 相似文献
93.
U. K. Klostermann R. Kinder G. Bayreuther M. Rührig G. Rupp J. Wecker 《Journal of magnetism and magnetic materials》2002,240(1-3):305-307
Sub-micron sized magnetic tunnel junctions are fabricated by electron beam lithography. Magnetoresistance measurements were done at crossed easy- and hard-axis fields and the critical switching curves for 3 different sub-μm junctions are discussed. Single domain like switching according to the Stoner and Wohlfarth model can be achieved, but Néel coupling effects and AAF stray field effects have to be controlled. 相似文献
94.
The very recently observed D*sJ(2463) meson is described as a
bound state in a unitarised meson model, owing its existence to the strong OZI-allowed
coupling to the nearby S-wave
threshold. By the same non-perturbative mechanism, the narrow axial-vector Ds1(2536) resonance shows up as a quasi-bound-state partner embedded in the
continuum. With the same model and parameters, it is also shown that the preliminary broad 1 + D1(2400) resonance and the established narrow 1 + D1(2420) may be similar
partners, as a result of the strong OZI-allowed
coupling to the nearby S-wave
threshold. The continuum bound states D1(2420) and Ds1(2536) are found to be mixtures of 33%
and 67%
, whereas their partners D1(2400) and D*sJ(2463) have more or less the opposite
-state content, but additionally with some
or
admixture, respectively. The employed mechanism also reproduces the ratio of the KL-KS mass difference and the KS width, by describing KL as a bound state embedded in the
continuum. The models results for
states containing one b quark are also discussed.Received: 7 June 2003, Revised: 20 October 2003, Published online: 18 December 2003PACS:
12.40.Yx, 14.40.Aq, 14.40.Lb, 13.25.Es, 13.25.Ft, 13.75.Lb 相似文献
95.
Daniel M. Chang S. Gromelski R. Rupp J. E. Mulvaney 《Journal of polymer science. Part A, Polymer chemistry》1977,15(3):571-584
The synthesis of N-vinylcarbazole (VCbz) copolymers in which electron-accepting groups are incorporated into the polymer chain is reported. The acceptors were introduced by appropriate reactions of VCbz–vinyl acetate or VCbz–acryloyl chloride copolymers and consisted of 3,5-dinitrobenzoyl, 2,4-dinitrophenyl acrylate, β-2,4-dinitrophenoxy propionate, and trichlorobenzoquinone units. The copolymer containing the 3,5-dinitrobenzoyl units required no chloranil as a dopant to be photoconductive, and in fact showed a slightly improved photoresponse relative to conventional poly VCbz doped with external chloranil. 相似文献
96.
Spatially resolved amplitude and phase characterization of femtosecond optical pulses 总被引:5,自引:0,他引:5
Gallmann L Steinmeyer G Sutter DH Rupp T Iaconis C Walmsley IA Keller U 《Optics letters》2001,26(2):96-98
Ultrabroadband pulses exhibit a frequency-dependent mode size owing to the wavelength dependence of free-space diffraction. Additionally, rather complex lateral dependence of the temporal pulse shape has been reported for Kerr-lens mode-locked lasers and broadband amplifier chains and in frequency-domain pulse shapers, for example. We demonstrate an ultrashort-pulse characterization technique that reveals lateral pulse-shape variations by spatially resolved amplitude and phase measurements by use of spectral phase interferometry for direct electric-field reconstruction (SPIDER). Unlike with autocorrelation techniques, with SPIDER we can obtain spatially resolved pulse characterization even after the nonlinear process. Thus, with this method the spectral phase of the pulse can be resolved very rapidly along one lateral beam axis in a single measurement. 相似文献
97.
Photoinduced light scattering is a serious drawback that limits the applicability of thick holographic recording media but
provides valuable information on the recording medium. As long as there is no correlation between the scattering centers in
the crystal, photoinduced light scattering may be explained to result from the interference pattern of the incident beam and
the field scattered from a single point-like scattering center. The hologram of this ellipsoidally scattered wave field will
have practically the same structure in the reciprocal space modified by a response function which reflects the anisotropic
properties of the recording medium. We studied photoinduced light scattering in LiNbO3:Fe, a model system for photorefractive materials. The transmitted intensity in the stationary state of the scattering process
is investigated as a function of the reconstruction angle at different wavelengths and polarizations of the reconstructing
beam. The experimental results are analyzed by a simple phenomenological model based on the Ewald construction and can be
used to choose suitable conditions at which holographic scattering can be minimized as well as to extract some physical parameters
of the crystal.
Received: 27 September 2000 / Revised version: 1 December 2000 / Published online: 21 February 2001 相似文献
98.
Stefanie Krajewski Johannes Rheinlaender Philip Ries Denis Canjuga Carmen Mack Lutz Scheideler Tilman E. Schäffer Jürgen Geis-Gerstorfer Hans-Peter Wendel Frank Rupp 《Analytical and bioanalytical chemistry》2014,406(14):3395-3406
Implant-related infections are a major challenge in clinical routine because of severe complications, for example infective endocarditis (IE). The purpose of this study was to investigate the real-time interaction of S. gordonii with proteins and cells important in the development of IE, in a flow system, by use of a quartz-crystal microbalance (QCM). Acoustic sensors were biologically modified by preconditioning with sterile saliva, platelet-poor plasma (PPP), or platelet-rich plasma (PRP), followed then by perfusion of a bacterial suspension. After perfusion, additional fluorescence and scanning electron microscopic (SEM) studies were performed. The surface structure of S. gordonii was analyzed by atomic force microscopy (AFM). Compared with S. gordonii adhesion on the abiotic sensor surface following normal mass loading indicated by a frequency decrease, adhesion on saliva, PPP, or PRP-conditioned sensors resulted in an increase in frequency. Furthermore, adhesion induced slightly increased damping signals for saliva and PPP-coated sensors but a decrease upon bacterial adhesion to PRP, indicating the formation of a more rigid biofilm. Microscopic analysis confirmed the formation of dense and vital bacterial layers and the aggregation of platelets and bacteria. In conclusion, our study shows that the complex patterns of QCM output data observed are strongly dependent on the biological substrate and adhesion mechanisms of S. gordonii. Overall, QCM sheds new light on the pathways of such severe infections as IE. 相似文献
99.
Tunable Aryl Alkyl Ionic Liquids with Weakly Coordinating Tetrakis((1,1,1,3,3,3‐hexafluoropropan‐2‐yl)oxy)borate [B(hfip)4] Anions
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Maria Kaliner Dr. Alexander Rupp Prof. Dr. Ingo Krossing Prof. Dr. Thomas Strassner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(29):10044-10049
Weakly coordinating borate or aluminate anions have recently been shown to yield interesting properties of the resulting ionic liquids (ILs). The same is true for large phenyl‐substituted imidazolium cations, which can be tuned by the choice, position, or number of substituents on the aromatic ring. We were therefore interested to combine these aryl alkyl imidazolium cations with the weakly coordinating tetrakis((1,1,1,3,3,3‐hexafluoropropan‐2‐yl)oxy)borate [B(hfip)4]? anions to study the physical properties and viscosities of these ionic liquids. Despite the large size and high molecular weight of these readily available ILs, they are liquid at room temperature and show remarkably low glass transition points and relatively high decomposition temperatures. 相似文献
100.
This study investigates grades 5 and 6 science, technology, engineering, and mathematics (STEM) teachers' planned and actualized engineering design‐based instruction, the instruments used to characterize their efforts, and the implications this work has for teachers' implementations of an integrated approach to STEM education. Participants included 23 STEM teachers from six schools (three rural, two suburban, and one urban). Data were gathered via lesson implementation plans and classroom observations. Teachers demonstrated strength in planning for standards‐ and engineering design‐based lessons, incorporating engineering practices within their respective implementation plans, and aligning their plans with content and design process standards. Missing from their plans was attention to science concepts and their placement, use, and application within a design task. Classroom observations indicated that the teacher participants gave priority to “front loading,” the design process by concentrating more of their instructional time on problem identification and planning and less time on testing designs, communicating performance results, and redesigning. Measures utilized in this study provided insight into the content of teachers' planning and subsequent instruction and suggest potential for capturing content planning in the context of classrooms in which teachers are attempting to integrate novel curriculum, such as the new standards for engineering practices. 相似文献