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131.
It is proven that for a certain class of singular nonlinear Schrödinger equations there exist stationary ground state and oscillatory solutions. Furthermore the existence of those solitary wave type solutions is considered which do not necessarely vanish at infinity. The results are applied to problems from plasma physics; to superfluid films, and to the Heisenberg ferromagnet spin chain.  相似文献   
132.
A method was developed for determination of St. John's wort marker compounds hypericin, pseudohypericin, hyperforin, and adhyperforin in functional foods. Solid-phase extraction provided analyte extraction and significant sample cleanup prior to analysis using liquid chromatography (LC) with UV and fluorescence detection. In addition to quantification using LC-UV, confirmation was made with electrospray ionization LC mass spectrometry (LC/MS). Several commercially available tea and drink products claiming to contain St. John's wort were tested. Recoveries ranged from 51 to 98% for the liquid samples. Comparison of the concentrations in 4 St. John's wort teas showed a variation in analyte concentration (1044-10 ng/mL marker compounds in brewed tea) and composition. No marker compounds were found in the beverages, indicating possible decomposition of the marker compounds caused by low pH and/or exposure to light. A solvent extraction procedure was developed for analysis of the marker compounds from solid samples. Analytes were detected at low parts per million, with an average recovery of 75%. No St. John's wort components were found in the 2 solid functional food samples analyzed.  相似文献   
133.
In this paper we present a spectroscopic study of chlorophyll a in solutions and in anhydrous polyvinyl alcohol films. Absorption, excitation and emission spectra, combined with fluorescence lifetime and time-resolved anisotropy measurements show that chlorophyll a in anhydrous polyvinyl alcohol films exists in a purely monomeric state. Furthermore, it appears that the monomeric chlorophyll a exhibits an efficient excitation energy transfer in this polyvinyl alcohol matrix. These results are rationalized in terms of a model in which the chlorophyll a molecules are located within pockets, formed by the polymer chains. It is concluded that the chlorophyll a-anhydrous polyvinyl alcohol film is a suitable system for studying energy transfer processes, especially because the factors governing energy transfer such as mutual orientation and separation of the molecules can easily be controlled.  相似文献   
134.
135.
Preliminary results of a selected few recent experiments at JLab are presented.  相似文献   
136.
A novel series of proflavine ureas, derivatives 11a–11i, were synthesized on the basis of molecular modeling design studies. The structure of the novel ureas was obtained from the pharmacological model, the parameters of which were determined from studies of the structure-activity relationship of previously prepared proflavine ureas bearing n-alkyl chains. The lipophilicity (LogP) and the changes in the standard entropy (ΔS°) of the urea models, the input parameters of the pharmacological model, were determined using quantum mechanics and cheminformatics. The anticancer activity of the synthesized derivatives was evaluated against NCI-60 human cancer cell lines. The urea derivatives azepyl 11b, phenyl 11c and phenylethyl 11f displayed the highest levels of anticancer activity, although the results were only a slight improvement over the hexyl urea, derivative 11j, which was reported in a previous publication. Several of the novel urea derivatives displayed GI50 values against the HCT-116 cancer cell line, which suggest the cytostatic effect of the compounds azepyl 11b–0.44 μM, phenyl 11c–0.23 μM, phenylethyl 11f–0.35 μM and hexyl 11j–0.36 μM. In contrast, the novel urea derivatives 11b, 11c and 11f exhibited levels of cytotoxicity three orders of magnitude lower than that of hexyl urea 11j or amsacrine.  相似文献   
137.
Pulsed field gradient nuclear magnetic resonance (PFG-NMR) and NMR imaging were used to study temporal and spatial domains of an electrokinetically-driven mobile phase through open and packed segments of capillaries. Characteristics like velocity distribution and an asymptotic dispersion are contrasted to viscous flow behavior. We show that electroosmotic flow in microchannel geometries can offer a significant performance advantage over the pressure-driven flows at comparable Peclét numbers, indicating that velocity extremes in the pore space of open tubes and packed beds are drastically reduced. An inherent problem of capillary electrochromatography that we finally address is the existence of wall effects when in the general case the surface zeta-potentials of the capillary inner wall and the adsorbent particles are different. Using dynamic NMR microscopy we were able resolve this systematic velocity inequality of the flow pattern which strongly influences axial dispersion and may be responsible for long time-tails of velocity distribution in the mobile phase.  相似文献   
138.
 To implement the St. Vincent Declaration Action Programme, initiatives have been started in the quality development of diabetes care across Europe. The main elements of the quality development cycle implemented in our hospital were realized by the use of the software package ‘CamitPro’ and participation in ‘the DiabCare Q-net NL’ network. From 1997 to 1999, 955, 1468, and 1624 patients with diabetes mellitus type 2 were integrated in the DiabCare Q-net NL network by using ‘CamitPro’ software, respectively. These patients showed substantial improvement in all of the clinical measures monitored. In addition, there was a drop in HbA1c level. From 1997 to 1999, an HbA1c interval of 5.1%–8.3% (mean up to mean +4SD) was recorded for 66%, 76% and 81% of the patients, respectively. An extension of the use of the software to a pan-European level should markedly improve diabetes care throughout the community. Received: 10 July 2000 / Accepted: 10 July 2000  相似文献   
139.
1-Methyl-7-dimethylamino quinolinium tetrafluoroborate, a highly stable, highly fluorescent color-shifting mobility sensitive fluorescent probe was employed for detecting the glass transition and phase transitions, notably crystallization, in polymers and polymer blends. Glass transitions in amorphous and semi-crystalline polymers were detected by a change in gradient in emission wavelength λmax versus T plots. Crystallization resulted in discrete blue shifts in λmax versus T plots. Selective probing of PMMA in a PS/PMMA blend, down to a PMMA content of 1%, was demonstrated. Dielectric relaxation spectroscopy has established a clear link between the mobility of dipoles in PMMA and the emission wavelength of the fluorescent probe.  相似文献   
140.
The 2H(e,e(')p)n cross section was measured in Hall A of the Thomas Jefferson National Accelerator Facility near the top of the quasielastic peak (x(Bj)=0.964) at a four-momentum transfer squared, Q(2)=0.665 (GeV/c) (2) (omega=0.368 GeV, W=2.057 GeV), and for recoil momenta up to 550 MeV/c. The measured cross section deviates by 1-2sigma from a state-of-the-art calculation at low recoil momenta. At high recoil momenta the cross section is well described by the same calculation; however, in this region, final-state interactions and interaction currents are predicted to be large, and alternative choices of nucleon-nucleon potential and nucleon current operator may result in significant spread in the calculations.  相似文献   
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