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301.
Parvathy Nancy Nithin Joy Sivakumaran Valluvadasan Reji Philip Sabu Thomas Rodolphe Antoine Nandakumar Kalarikkal 《Molecules (Basel, Switzerland)》2022,27(22)
Graphene quantum dots (GQDs), the zero dimensional (0D) single nanostructures, have many exciting technological applications in diversified fields such as sensors, light emitting devices, bio imaging probes, solar cells, etc. They are emerging as a functional tool to modulate light by means of molecular engineering due to its merits, including relatively low extend of loss, large outstretch of spatial confinement and control via doping, size and shape. In this article, we present a one pot, facile and ecofriendly synthesis approach for fabricating GQDs via pulsed laser irradiation of an organic solvent (toluene) without any catalyst. It is a promising synthesis choice to prepare GQDs due to its fast production, lack of byproducts and further purification, as well as the control over the product by accurate tuning of laser parameters. In this work, the second (532 nm) and third harmonic (355 nm) wavelengths of a pulsed nanosecond Nd:YAG laser have been employed for the synthesis. It has been found that the obtained GQDs display fluorescence and is expected to have potential applications in optoelectronics and light-harvesting devices. In addition, nonlinear optical absorption of the prepared GQDs was measured using the open aperture z-scan technique (in the nanosecond regime). These GQDs exhibit excellent optical limiting properties, especially those synthesized at 532 nm wavelength. 相似文献
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Robert M. Hughes David J. Freeman Kelsey N. Lamb Rebecca M. Pollet Weston J. Smith David S. Lawrence 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(41):12232-12236
An optogenetic Bax has been designed that facilitates light‐induced apoptosis. We demonstrate that mitochondrial recruitment of a genetically encoded light‐responsive Bax results in the release of mitochondrial proteins, downstream caspase‐3 cleavage, changes in cellular morphology, and ultimately cell death. Mutagenesis of a key phosphorylatable residue or modification of the C‐terminus mitigates background (dark) levels of apoptosis that result from Bax overexpression. The mechanism of optogenetic Bax‐mediated apoptosis was explored using a series of small molecules known to interfere with various steps in programmed cell death. Optogenetic Bax appears to form a mitochondrial apoptosis‐induced channel analogous to that of endogenous Bax. 相似文献
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Giuliana Gorrasi Mariarosaria Tortora Vittoria Vittoria Eric Pollet Michael Alexandre Philippe Dubois 《Journal of Polymer Science.Polymer Physics》2004,42(8):1466-1475
Poly(ε‐caprolactone) (PCL) chains grafted onto montmorillonite modified by a mixture of nonfunctional ammonium salts and ammonium‐bearing hydroxyl groups were prepared. The clay content was fixed to 3 wt %, whereas the hydroxyl functionality was 25, 50, 75, and 100%, obtaining an intercalated or exfoliated system. The transport properties of water and dichloromethane vapors and the mechanical properties were investigated. The mechanical and dynamic mechanical analyses showed improvement of the nanocomposite elastic modulus in a wide temperature range. Interestingly, for the higher hydroxyl contents (50, 75, and 100%), the decrease of modulus at higher temperature, due to the PCL crystalline melting, did not lead to the loss of mechanical consistence of the samples. Consequently, they revealed a measurable modulus up to 120 °C, a much higher temperature with respect to pure PCL. Water sorption was investigated in the entire activity range, and a lower sorption was observed on increasing the hydroxyl content, up to the sample with 100% hydroxyl content, which turned to be completely impermeable, even in liquid water. The sample with 75% hydroxyl content showed a threshold activity (a = 0.4) below which it was impermeable to water vapor. Also, the diffusion parameters decreased when the hydroxyl content increased, up to the 100% sample, which showed zero diffusion. The diffusion parameters of an organic vapor, dichloromethane, also exhibited a decreasing value on increasing the hydroxyl content in the nanocomposites. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1466–1475, 2004 相似文献
309.
Jun‐Liang Liu Kasper S. Pedersen Samuel M. Greer Itziar Oyarzabal Abhishake Mondal Stephen Hill Fabrice Wilhelm Andrei Rogalev Alain Tressaud Etienne Durand Jeffrey R. Long Rodolphe Clrac 《Angewandte Chemie (International ed. in English)》2020,59(26):10306-10310
Silicon‐mediated fluoride abstraction is demonstrated as a means of generating the first fluorido‐cyanido transition metal complexes. This new synthetic approach is exemplified by the synthesis and characterization of the heteroleptic complexes, trans‐[MIVF4(CN)2]2? (M=Re, Os), obtained from their homoleptic [MIVF6]2? parents. As shown by combined high‐field electron paramagnetic resonance spectroscopy and magnetization measurements, the partial substitution of fluoride by cyanide ligands leads to a marked increase in the magnetic anisotropy of trans‐[ReF4(CN)2]2? as compared to [ReF6]2?, reflecting the severe departure from an ideal octahedral (Oh point group) ligand field. This methodology paves the way toward the realization of new heteroleptic transition metal complexes that may be used as highly anisotropic building‐blocks for the design of high‐performance molecule‐based magnetic materials. 相似文献
310.
The k-moment method for the narrow band modeling of radiative properties of nonuniform gaseous media
Frédéric André Rodolphe Vaillon 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(2):258-268
Moments of the absorption coefficient distribution function are used for the derivation of statistical narrow band (SNB) model parameters of nonuniform optical paths in gases. The approach yields approximations for the path-averaged first- and second-order k-moments from which equivalent SNB parameters are determined in the frame of the Malkmus model. The approach is assessed through comparisons with LBL data. The nonuniform approximation is shown to enable the computation of transmissivities and radiation intensities with accuracy similar to or higher than those achieved by the Curtis-Godson one. 相似文献