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131.
Dumitrescu Mihail Saarinen Mika Guina Mircea Komsa Hannu Pessa Markus 《Optical and Quantum Electronics》2003,35(6):589-613
Resonant cavity light emitting diodes (RC-LEDs) and vertical cavity surface emitting lasers (VCSELs) for the red wavelength range are presented in the paper. A wide variety of simulation tools were employed in the device design and optimization and the good agreement between simulations and measurements enabled effective device development. Our red wavelength range RC-LEDs were mainly intended for short-haul communication systems based on polymethyl methacrylate plastic optical fiber and were optimized accordingly. They are achieving, under different structure and working regime variants, high output power (15 mW), high external efficiency (9.5%), record small-signal modulation bandwidth (f
-3dB
up to 350 MHz), error-free back-to-back transmission rates beyond 622 Mbits/s, adjustable far-field pattern and good POF coupling efficiency with reasonably wide tolerances and without using auxiliary optics. In view of the possible use of graded-index POFs, free-space transmission and other high bandwidth or high spectral purity applications, VCSELs in the red wavelength range were also realized. They have achieved sub-milliamp room-temperature (RT) continuous-wave (CW) lasing for an 8 m diameter emission window and exhibited an external quantum efficiency of 6.65% for 10 m devices in RT CW operation. The VCSEL structures were far from optimal – not even incorporating all the RC-LED structure refinements – and significant improvement in performance characteristics are predicted for the optimized layer structure. 相似文献
132.
The reaction of 5H,5Cl-dibenzo[a,d]cycloheptatriene with nitrobenzene was investigated under both thermal (210 degrees C) and ultrasonic (50 degrees C, 40 kHz) activation. The reaction products of both procedures are similar, but their amounts depend on the activation source. To account for the products a common electron transfer reaction is postulated through the dibenzotropylium cation. The differences between the thermal and ultrasonic process is thought to arise from the role of nitrobenzene as oxidant. Under thermal conditions this occurs throughout the reaction mixture but under sonication it occurs only in the cavitation bubble and in its immediate vicinity. 相似文献
133.
Single-molecule surface enhanced resonance Raman spectroscopy of the enhanced green fluorescent protein 总被引:1,自引:0,他引:1
Habuchi S Cotlet M Gronheid R Dirix G Michiels J Vanderleyden J De Schryver FC Hofkens J 《Journal of the American Chemical Society》2003,125(28):8446-8447
In the present contribution, we demonstrated that surface-enhanced resonance Raman scattering spectra from single green fluorescent proteins (GFPs) were obtained. The most important findings are the direct detection of the conversion between a deprotonated and a protonated form of the chromophore at the single-molecule level via the corresponding vibrational fingerprints, and the fact that the enhanced green fluorescent protein (EGFP) also shows a high surface enhanced resonance Raman scattering (SERRS) signal. Our findings show the potential of the technique to study structural dynamics of protein molecules at a single-molecule level. 相似文献
134.
The principles and application of a method for the microdetermination of substances on small paper disks are described. Photometric measurements are made at 2 wavelengths, thus eliminating the errors due to inhomogeneity in the paper. A simple device for serial determinations that can be adapted to a common spectrophotometer is described. Microdetermination of RNA with measurement at 260 and 350 mμ is given as an example of the proposed method, and the best means of correcting the effect of paper inhomogeneity is established. Amounts of RNA in the range 0.8–4 μg can be determined with a mean error of ±0.03μg , using 5 μl of solution. 相似文献
135.
The rate of pointwise convergence for a sequence of positive linear operators Ln approximating continuous functions on a finite interval is considered. The complete asymptotic expansion for the operators Ln as n tends to infinity is presented. It turns out that the central factorial numbers of first and second kind play an important role in the asymptotic expansion. The present work is an extension to that reported by Ivan and Raa. 相似文献
136.
Mircea Geanău 《Southeast Asian Bulletin of Mathematics》2001,25(1):105-110
One consider the variety of the unitary binary group in n variables and it is shown that this algebraic variety is rational and it has n2 parameters. Then it is given a parametrical rational representation of this variety.AMS Subject Classification (1991) 20G20 相似文献
137.
Using feedback theory, we analyze the gain of an all-optical gain-clamped praseodymium-doped fluoride fiber amplifier (AOGC PDFFA) for eight-channel multiwavelength operation. We demonstrate by numerical simulation that gain stabilization is achieved when the open-loop gain is higher than the feedback path attenuation. If this condition is fulfilled, the gain stabilizes to a value equal to the feedback path attenuation and is not influenced by the pump power, input signal power, number of channels, doped fiber length, or any other doped fiber parameter. In our setup the AOGC PDFFA noise figure is 0.12 dB lower than the open-loop PDFFA noise figure. 相似文献
138.
Dr. Yearin Byun Lilia S. Xie Patrick Fritz Timur Ashirov Prof. Mircea Dincă Prof. Ali Coskun 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(35):15278-15282
Dimensionality plays an important role in the charge transport properties of organic semiconductors. Although three-dimensional semiconductors, such as Si, are common in inorganic materials, imparting electrical conductivity to covalent three-dimensional organic polymers is challenging. Now, the synthesis of a three-dimensional π-conjugated porous organic polymer (3D p-POP) using catalyst-free Diels–Alder cycloaddition polymerization followed by acid-promoted aromatization is presented. With a surface area of 801 m2 g−1, full conjugation throughout the carbon backbone, and an electrical conductivity of 6(2)×10−4 S cm−1 upon treatment with I2 vapor, the 3D p-POP is the first member of a new class of permanently porous 3D organic semiconductors. 相似文献
139.
Loredana Vacareanu Oana Iuliana Negru Mircea Grigoras 《Journal of polymer science. Part A, Polymer chemistry》2018,56(22):2565-2573
A simple method for synthesis of polymers containing shape persistent imine macrocycles as nanohoops in the main chain is studied. It is based on the cyclocondensation reaction carried out in solution and room temperature of triphenylamine-based tetraaldehyde compounds with (R,R)-trans-1,2-diaminocyclohexane. The pristine polymer P1 bearing long alkyl groups is soluble during the synthesis but becomes insoluble after precipitation due to the strong and multiple C H/π and π-π stacking intermolecular interactions from arene–arene species and entanglement and interpenetrating of flexible alkyl groups inside of rigid macrocycle hollow. Polymer without any solubilizing groups ( P2 ) separates during the polymerization as an insoluble material. Both polymers are amorphous and have good thermal and environmental stability. They have a low surface area because discrete nanovoids introduced by macrocycles are disconnected in the amorphous polymers and non-accessible for gas adsorption. Polymers have inherent luminescent properties due to triphenylamine groups and chirality derived from (R,R)-conformation of the cyclohexane skeleton. In presence of picric acid (PA), the polymer fluorescence in solid state or suspension is strongly quenched, thus the polymers can work as efficient fluorescent probes toward nitrophenolic compounds. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2565–2573 相似文献
140.
Mircea Dan Valerie Pralong Nicolae Vaszilcsin Andrea Kellenberger Narcis Duteanu 《Journal of Solid State Electrochemistry》2011,15(6):1227-1233
The paper presents the electrochemical investigation of mixed oxide YBaCo4O7 in alkaline aqueous solution during oxygen insertion/release. The electrochemical behaviour of YBaCo4O7 has been studied by cyclic voltammetry and electrochemical impedance spectroscopy. In correlation with these techniques,
the compound morphology was determined by scanning electron microscopy. Based on the results obtained, the electrochemical
processes occurring at the interface mixed oxide (YBaCo4O7)/electrolyte solution have been identified, and furthermore a mechanism of YBaCo4O7 oxidation/reduction in alkaline aqueous solutions has been proposed. 相似文献