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71.
F. Soldevila E. Irles V. Durán P. Clemente Mercedes Fernández-Alonso Enrique Tajahuerce Jesús Lancis 《Applied physics. B, Lasers and optics》2013,113(4):551-558
We present an optical system that performs polarimetric spectral imaging with a detector with no spatial resolution. This fact is possible by applying the theory of compressive sampling to the data acquired by a sensor composed of an analyzer followed by a commercial fiber spectrometer. The key element in the measurement process is a digital micromirror device, which sequentially generates a set of intensity light patterns to sample the object image. For different configurations of the analyzer, we obtain polarimetric images that provide information about the spatial distribution of light polarization at several spectral channels. Experimental results for colorful objects are presented in a spectral range that covers the visible spectrum and a part of the NIR range. The performance of the proposed technique is discussed in detail, and further improvements are suggested. 相似文献
72.
Enantiomerically pure α-hydroxy-aldehydes, key intermediates for the synthesis of arachidonic acid metabolites, are prepared from D-mannitol by nucleophilic opening of diastereoisomeric diepoxides. 相似文献
73.
Summary The parameters appearing in an effective tight-binding Hamiltonian are shown to be simply related to the tunnelling currents
and the overlap between the different orbitals of the constituent atoms. Different systems are considered and the results
show that our approach applies both to molecular and condensed-matter systems.
Riassunto Si mostra che i parametri presenti in una hamiltoniana efficace a legame forte sono correlati semplicemente alle correnti di tunnel e alla sovrapposizione tra i diversi orbitali degli atomi costituenti. Si considerano diversi sistemi e i risultati mostrano che il nostro approccio si applica sia a sistemi molecolari che di materia condensata.
Резюме ПоказЫвается, что параметрЫ, появляющиеср в эффективном Гамильтониане в приближении силъной связи, связнЫ с туннелънЫми токами и перекрЫтием между разяичнЫми орбиталями составляюших атомов. Рассматриваются различнЫе системЫ. ПолученнЫе результатЫ показЫвают, что наш подход применим к молекулярнЫм системам и к конденсироваииому веществу.相似文献
74.
Ricardo Durán 《Numerische Mathematik》1991,59(1):769-778
Summary We prove a discrete inf-sup condition for a mixed plate element introduced by Arnold and Falk.By using this condition, we obtain optimal error estimates for the shear strain which are valid uniformly in the plate thickness.This research was performed while the author was visiting the Center for Applied Mathematics, Purdue University, West Lafayette, IN 47907, USA 相似文献
75.
Guillermo Durán-Solares Walter Fugarolas-Gómez Naytzé Ortíz-Pastrana Horacio López-Sandoval Tayde Osvaldo Villaseñor-Granados Angelina Flores-Parra 《Journal of Coordination Chemistry》2018,71(11-13):1935-1958
AbstractSpectroscopic and single crystal X-ray diffraction studies of coordination compounds of CoII, NiII, ZnII, and PdII with phenylsulfonyl imidazole and benzimidazole derivatives (2-mfsiz, 2-mfsbz) were performed. The relevance of non-covalent interactions on the stabilization of intra and intermolecular arrangements in the ligands and their coordination compounds was investigated. The imidazole 2-mfsiz ligand presents two enantiomeric conformers, where the ethylphenylsulfone moiety stabilizes intermolecular lone pair···π (S–O···π(phe)) and H···π contacts, while its tetrahedral coordination compounds, [M(2-mfsiz)2X2] (M2+?=?Co, Ni, Zn; X?=?Cl, Br) showed intramolecular lone pair···π interactions (S–O···π(iz)). On the other hand, compounds [Cu2(2-mfsiz)2(µ2-AcO)4] and trans-[Pd(2-mfsiz)2Cl2] do not present lone pair···π interactions due to the metal ion geometry (square base pyramidal or square planar), which leads to formation of π(iz)···π(phe) interactions. For the benzimidazole ligand 2-mfsbz, an intramolecular, H(phe)···π(bz) contact was observed, remaining in its tetrahedral and octahedral coordination compounds, [M(2-mfsbz)2X2] (M2+?=?Co, Zn; X?=?Cl, Br, NO3). This interaction limits the free rotation of the ethylphenylsulfone moiety for stabilization of an intermolecular lone pair···π interaction (S–O···π(iz)). The dimeric [Zn2(2-mfsiz)2(µ2-AcO)4] compound has a π(bz)···π(phe) contact. Theoretical calculations confirmed the non-covalent interactions in the ligands and their coordination compounds. 相似文献
76.
Prieto-Sagredo J Ricalde-Recchia I Durán-Lizarraga ME Gonsebatt ME Fanjul-Moles ML 《Photochemistry and photobiology》2000,71(4):487-492
This work studied the effect of light-stressors, irradiance and photoperiod length on the status of hemolymph glutathione in two species of crayfish, Procambarus clarkii and Procambarus digueti. Adult animals of each species were submitted to two experimental approaches: (1) two batches of each species were placed under low or high light irradiant conditions of light-dark (LD) 24 h cycles of two different photoperiod lengths, one normal LD 12: 12 and one extreme LD 20:4 low and high irradiance for 10 weeks. Time-dependent light changes on hemolymph glutathione concentration were determined throughout the entire experimental period; and (2) three batches of the two species were submitted to independent treatments consisting of the same LD 12:12 cycles of high and low irradiance and 20:4 high-irradiance LD cycles. Reduced and oxidized glutathione hemolymph concentrations were determined and total glutathione was calculated. In addition midgut glutathione reductase activity in both species was determined. The two species showed different hemolymph glutathione reactivity and glutathione status for the two light parameters. Dissimilar responses of both species, as well as the rate of mortality of P. digueti represent specific differences in the metabolic responses, as well as tolerance to photo-oxidative stress produced by light. The role of glutathione in the tolerance of crayfish to photo-oxidative stress is discussed. 相似文献
77.
Enrique Durán-Páramo Héctor Molina-Jiménez Marco A. Brito-Arias Fabián Robles-Martínez 《Applied biochemistry and biotechnology》2004,114(1-3):381-388
Gibberellic acid production was studied in different fermentation systems. Free and immobilized cells of Gibberella fujikuroi cultures in shakeflask, stirred and fixed-bed reactors were evaluated for the production of gibberellic acid (GA3). Gibberellic acid production with free cells cultured in a stirred reactor reached 0.206 g/L and a yield of 0.078 g of GA3/g biomass. 相似文献
78.
79.
A. Mu?oz de la Pe?a I. Durán-Merás M. D. Moreno F. Salinas M. Martínez Galera 《Fresenius' Journal of Analytical Chemistry》1995,351(6):571-576
The resolution of ternary mixtures of salicylic, salicyluric and gentisic acids has been accomplished by partial least squares (PLS) and principal component regression (PCR) multivariate calibration. The total luminescence information of the compounds has been used to optimize the spectral data set to perform the calibration. A comparison between the predictive ability of the three multivariate calibration methods, PLS-1, PLS-2 and PCR, on three spectral data sets, excitation, emission and synchronous spectra, has been performed. The excitation spectrum has been the best scanning path for salicylic and salicyluric acid determinations, while the emission spectrum has been the best for the gentisic acid determination. The convenience of analysing the total luminescence spectrum information when using multivariate calibration methods on fluorescence data is demonstrated. 相似文献
80.