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21.
V. A. Kuz’mitskii É. I. Zen’kevich V. I. Gael V. N. Knyukshto A. M. Shul’ga E. G. Levinson A. F. Mironov 《Journal of Applied Spectroscopy》1997,64(6):778-788
The porphyrin-chlorine heterodimer P-O-Chl, in which porphyrin and chlorine fragments are single esterbonded in a covalent
manner, is investigated experimentally and theoretically. From absorption and polarized-fluorescence spectra of two stable
P-O-Chl isomers it follows that the porphyrin and chlorine fragments preserve their individuality, and their weak interaction
does not change the basic photophysical parameters of the chlorine fragment in a temperature interval of 77–293 K. Based on
calculations by the method of molecular mechanics with standard parameterization of the force field and the CNDO/S method
and comparison of their results with the data on polarized fluorescence, the structure of one of the two isomers is substantiated.
From CNDO/S calculations, the authors estimated the energy of the states with charge transfer in the P-O-Chl system, whose
lower levels are above the levels of local excited Q-states of the interacting porphyrin and chlorine fragments.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 6, pp. 766–775, November–December, 1997. 相似文献
22.
The phenomenon of the existence of optimal trajectories having an infinite number of tangent points with the boundary of the
phase constraint is studied. The optimal synthesis and the structure of the corresponding Lagrangian manifolds are obtained.
The main tool is the blowing up procedure for the resolution of the singularities of the Poincaré mapping of the constraint
boundary on itself. A singularity appears at the point of accumulation of the tangent points with the boundary. 相似文献
23.
Gael Pentang Rotem Shlomo LanzmanPhilpp Heusch Anja Müller-LutzDirk Blondin Gerald AntochHans-Jörg Wittsack 《Magnetic resonance imaging》2014
Purpose
To assess the feasibility and to optimize imaging parameters of diffusion kurtosis imaging (DKI) in human kidneys.Methods
The kidneys of ten healthy volunteers were examined on a clinical 3 T MR scanner. For DKI, respiratory triggered EPI sequences were acquired in the coronal plane (3 b-values: 0, 300, 600 s/mm2, 30 diffusion directions). A goodness of fit analysis was performed and the influence of the signal-to-noise ratio (SNR) on the DKI results was evaluated. Region-of-interest (ROI) measurements were performed to determine apparent diffusion coefficient (ADC), fractional anisotropy (FA) and mean kurtosis (MK) of the cortex and the medulla of the kidneys. Intra-observer and inter-observer reproducibility using Bland-Altman plots as well as subjective image quality of DKI were examined and ADC, FA, and MK parameters were compared.Results
The DKI model fitted better to the experimental data (r = 0.99) with p < 0.05 than the common mono-exponential ADC model (r = 0.96).Calculation of reliable kurtosis parameters in human kidneys requires a minimum SNR of 8.31 on b = 0 s/mm2 images.Corticomedullary differentiation was possible on FA and MK maps. ADC, FA and MK revealed significant differences in medulla (ADC = 2.82 × 10− 3 mm2/s ± 0.25, FA = 0.42 ± 0. 05, MK = 0.78 ± 0.07) and cortex (ADC = 3.60 × 10− 3 mm2/s ± 0.28, FA = 0.18 ± 0.04, MK = 0.94 ± 0.07) with p < 0.001.Conclusion
Our initial results indicate the feasibility of DKI in the human kidney presuming an adequate SNR. Future studies in patients with kidney diseases are required to determine the value of DKI for functional kidney imaging. 相似文献24.
Gael N. N. Neba Ambe Carlo Breda Avninder Singh Bhambra Randolph R. J. Arroo 《Molecules (Basel, Switzerland)》2022,27(22)
The importance of the circadian clock in maintaining human health is now widely acknowledged. Dysregulated and dampened clocks may be a common cause of age-related diseases and metabolic syndrome Thus, circadian clocks should be considered as therapeutic targets to mitigate disease symptoms. This review highlights a number of dietary compounds that positively affect the maintenance of the circadian clock. Notably the polymethoxyflavone nobiletin has shown some encouraging results in pre-clinical experiments. Although many more experiments are needed to fully elucidate its exact mechanism of action, it is a promising candidate with potential as a chronotherapeutic agent. 相似文献
25.
Amewu R Stachulski AV Ward SA Berry NG Bray PG Davies J Labat G Vivas L O'Neill PM 《Organic & biomolecular chemistry》2006,4(24):4431-4436
Unsymmetrical dispiro- and spirotetraoxanes have been designed and synthesized via acid-catalyzed cyclocondensation of bis(hydroperoxides) with ketones. Incorporation of water-soluble and polar functionalities, via reductive amination and amide bond formation, produces several analogues with low nanomolar in vitro antimalarial activity. Several analogues display an unprecedented level of oral antimalarial activity for this class of endoperoxide drug. 相似文献
26.
David Harris Gael M. Martin Indeewara Perera D. S. Poskitt 《Journal of computational and graphical statistics》2019,28(1):92-104
The focus of this article is on the quantification of sampling variation in frequentist probabilistic forecasts. We propose a method of constructing confidence sets that respects the functional nature of the forecast distribution, and use animated graphics to visualize the impact of parameter uncertainty on the location, dispersion, and shape of the distribution. The confidence sets are derived via the inversion of a Wald test, and the ellipsoid that defines the boundary of the set computed numerically. A wide range of linear and nonlinear time series models—encompassing long memory, state space, and mixture specifications—is used to demonstrate the procedure, based on artificially generated data. An empirical example in which distributional forecasts of both financial returns and its stochastic volatility are produced is then used to illustrate the practical importance of accommodating sampling variation in the manner proposed. 相似文献
27.
Florian Maire Gael Coadou Laetitia Cravello Catherine M. Lange 《Journal of the American Society for Mass Spectrometry》2013,24(2):238-248
We reported the use of ion mobility (IM) combined with mass spectrometry (MS) as an analytical tool to investigate low generation polyamidoanine (PAMAM) dendrimers. This analytical approach has been employed to separate ions of defective structures with different charge state but exactly the same m/z value. Tandem mass spectrometry (MS/MS) after IM separation allowed a comprehensive structural characterization of defective dendrimers. In addition, IM was used to evaluate the collision cross-sections of ions of perfect dendrimers. They showed a good correlation with calculated collision cross-sections obtained by the trajectory method (TM) and were also consistent with dimensions reported by other established analytical methods. 相似文献
28.
TiO2‐mediated photocatalysis is widely used in a variety of applications and products in the envi‐ronmental and energy fields, including photoelectrochemical conversion, self‐cleaning surfaces, and especially water purification systems. The dimensionality of the structure of a TiO2 material can affect its properties, functions, and more specifically, its photocatalytic performance. In this work, the photocatalytic inactivation of Gram‐negative Escherichia coli using three photocatalysts, differ‐ing in their structure and other characteristics, was studied in a batch reactor under UVA light. The aim was to establish the disinfection efficiency of solid TiO2 compared with that of suspended cata‐lysts, widely considered as reference cases for photocatalytic water disinfection. The bacterial inac‐tivation profiles obtained showed that: (1) the photoinactivation was exclusively related to the quantity of photons retained per unit of treated volume, irrespective of the characteristics of the photocatalyst and the emitted light flux densities;(2) across the whole UV light range studied, each of the photocatalytic solids was able to achieve more than 2 log bacterial inactivation with less than 2 h UV irradiation;(3) none of the used catalysts achieved a total bacterial disinfection during the treatment time. For each of the catalysts the quantum yield has been assessed in terms of disinfec‐tion efficiency, the 2D material showed almost the same performance as those of suspended cata‐lysts. This catalyst is promising for supported photocatalysis applications. 相似文献
29.
Gyuzel Yu. Mitronova Dr. Vladimir N. Belov Dr. Mariano L. Bossi Dr. Christian A. Wurm Dr. Lars Meyer Dr. Rebecca Medda Dr. Gael Moneron Dr. Stefan Bretschneider Dr. Christian Eggeling Dr. Stefan Jakobs Dr. Stefan W. Hell Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(15):4407-4407
30.
We present a polarization-sensitive full-field optical coherence tomography system that can produce high-resolution images of the linear retardance and reflectivity properties of biological media. En face images can be delivered at a frame rate of 3.5 Hz by combination of interferometric images acquired by two CCD cameras in an interference microscope illuminated with a tungsten halogen lamp. Isotropic spatial resolution of approximately 1.0 microm is achieved. The technique is demonstrated on ex vivo muscle tissues. 相似文献