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131.
132.
In this paper, we investigate flows on discrete curves in , and . A novel interpretation of the one-dimensional Toda lattice hierarchy and reductions thereof as flows on discrete curves are given. 相似文献
133.
Versatile Aerogel Fabrication by Freezing and Subsequent Freeze‐Drying of Colloidal Nanoparticle Solutions 下载免费PDF全文
Axel Freytag Dr. Sara Sánchez‐Paradinas Suraj Naskar Natalja Wendt Dr. Massimo Colombo Giammarino Pugliese Jan Poppe Cansunur Demirci Imme Kretschmer Prof. Dr. Detlef W. Bahnemann Prof. Dr. Peter Behrens Dr. Nadja C. Bigall 《Angewandte Chemie (International ed. in English)》2016,55(3):1200-1203
A versatile method to fabricate self‐supported aerogels of nanoparticle (NP) building blocks is presented. This approach is based on freezing colloidal NPs and subsequent freeze drying. This means that the colloidal NPs are directly transferred into dry aerogel‐like monolithic superstructures without previous lyogelation as would be the case for conventional aerogel and cryogel fabrication methods. The assembly process, based on a physical concept, is highly versatile: cryogelation is applicable for noble metal, metal oxide, and semiconductor NPs, and no impact of the surface chemistry or NP shape on the resulting morphology is observed. Under optimized conditions the shape and volume of the liquid equal those of the resulting aerogels. Also, we show that thin and homogeneous films of the material can be obtained. Furthermore, the physical properties of the aerogels are discussed. 相似文献
134.
135.
Christoph Berthold Volker Presser Nadja Huber Klaus G. Nickel 《Journal of Thermal Analysis and Calorimetry》2011,103(3):917-923
The article shows how additional information can be obtained from coupling a self constructed DTA-system with a commercially
available BRUKER D8 DISCOVER GADDS XRD2-microdiffractometer. The dehydration process of gypsum to anhydrite in the temperature range from room temperature up to
723 K is used as an example. Due to the short measurement times of 10 s for each diffraction pattern the three phase transformations
from gypsum to anhydrite (anhydrite II) via the hemihydrate bassanite, a water-free bassanite structure (γ-anhydrite, anhydrite
III) were resolved in detail by recording the thermal signal and the diffraction pattern simultaneously. To the best of our
knowledge, this is the first observation of a completely reversible dehydration/rehydration process of the bassanite/γ-anhydrite-structure
around 373 K which is studied by coupled XRD and differential thermal analysis (DTA) measurements. 相似文献
136.
Nadja A. Simeth Paula de Mendoza Victor R. A. Dubach Marc C. A. Stuart Julien W. Smith Tibor Kudernac Wesley R. Browne Ben L. Feringa 《Chemical science》2022,13(11):3263
Molecular recognition-driven self-assembly employing single-stranded DNA (ssDNA) as a template is a promising approach to access complex architectures from simple building blocks. Oligonucleotide-based nanotechnology and soft-materials benefit from the high information storage density, self-correction, and memory function of DNA. Here we control these beneficial properties with light in a photoresponsive biohybrid hydrogel, adding an extra level of function to the system. An ssDNA template was combined with a complementary photo-responsive unit to reversibly switch between various functional states of the supramolecular assembly using a combination of light and heat. We studied the structural response of the hydrogel at both the microscopic and macroscopic scale using a combination of UV-vis absorption and CD spectroscopy, as well as fluorescence, transmission electron, and atomic force microscopy. The hydrogels grown from these supramolecular self-assembly systems show remarkable shape-memory properties and imprinting shape-behavior while the macroscopic shape of the materials obtained can be further manipulated by irradiation.Molecular recognition-driven self-assembly employing single-stranded DNA (ssDNA) as a template is a promising approach to access complex architectures from simple building blocks. 相似文献
137.
A theoretical model is developed which characterizes the physical process responsible for generating ultra-short, high-energy, mode-locked pulses in a normal GVD laser cavity with spectral filtering. Two physical parameters are critical to achieving optimal performance: the ratio of the filter bandwidth to the gain bandwidth and the placement of the output coupler in the laser cavity. The spectral filtering allows for the high-energy of typical normal GVD laser cavities to be maintained while the pulse intensity doubles and the FWHM reduces by an order of magnitude. This phenomenon is generic and ubiquitous to normal GVD mode-locking. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
138.
Apart from a number of known sesquiterpenoids, a novel chlorinated sesquiterpene lactone glucoside--13-chloro-3-O-β-d-glucopyranosylsolstitialin--has been isolated from the Southwestern European plant Leontodon palisae (Asteraceae, tribe Lactuceae). The structure has been established by high resolution mass spectrometry and 1D as well as 2D NMR spectroscopy. The compound represents the first naturally occurring chlorinated sesquiterpene lactone glucoside. The cytotoxicity of the new compound and related ones was evaluated using the MTT assay. 相似文献
139.
Zora?Popovi?Email author Gordana?Pavlovi? Vibor?Roje Nadja?Do?li? Dubravka?Matkovi?-?alogovi? Ivan?Leban 《Structural chemistry》2004,15(6):587-598
Three Schiff-bases of the Ar—CH—N—Ar type were synthesized from 2-hydroxy-1-naphthaldehyde and o- (1), m- (2), and p-nitroaniline (3) in order to investigate the shift of the keto-amine/enol-imine tautomeric equilibrium that arises by the introduction of the electron-withdrawal nitro group. The compounds have been investigated experimentally, in the solid state and in the solution, by IR, NMR, UV spectroscopy, and X-ray single crystal analysis, and theoretically by using density functional theory (DFT). The tautomeric equilibrium is strongly shifted towards the keto-amine form despite of the nitro group position at N-phenyl ring in the solid state of molecular structures of 1, 2, and 3 (especially indicated by C—O and C—N bond distances). The keto-amine tautomeric form of the compounds is characterized by a strong, resonance assisted hydrogen bond (RAHB) of the N—H O type (the N O distances are 2.530(8), 2.554(2) and 2.555(5) Å in 1, 2, and 3, respectively). The molecules are assembled in the crystalline state into a 3D HB network (1), centrosymmetrical dimers (2) or infinite chains (3) by the C—H O intermolecular hydrogen bonds. In contrast, UV/VIS spectra of the chloroform solution of the title compounds reveal predominance of the enol-imine form. The molecular geometries and relative stabilities of the compounds determined by using DFT find good agreement with the experimental data. 相似文献
140.
An analytic theory is presented that demonstrates that noise-induced amplitude and quadratic chirp jitter in a dispersion-managed soliton system can impose a fundamental transmission limit. Using a variational method, we show that the nonlinear amplitude and chirp dynamics are well approximated by a two-dimensional random-walk process. 相似文献