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941.
Daniela Babusca Larisa Popescu Liviu Sacarescu Dana Ortansa Dorohoi Dorina Creanga Lacramioara Anca Oprica 《Molecular Crystals and Liquid Crystals》2020,698(1):56-64
AbstractWe have designed an experimental study dedicated to silver nanotoxicity using a suspension of citrate-silver nanoparticles, obtained by photochemical reduction. Fine granularity of generally symmetrical shape nanoparticles were evidenced by tansmission electron microscopy. The localized surface plasmon resonance spectral band revealed the intensification of silver nanoparticle formation under UV exposure. The nanotoxicity of silver nanoparticles was tested on cereal sprouts by measuring the concentrations of chlorophylls and carotenes in the green tissue. The differences between control samples, supplied with distilled water and test samples, loaded with different volumes of silver nanoparticles suspension were analyzed statistically, and compared with literature reports. 相似文献
942.
Eugenia H.O. Valença Anita H.O. Souza Alaide H.A. Oliveira Silvio L. Valença Roberto Salvatori Maria I.R. Gonçalves Luiz A. Oliveira-Neto Alana D. Barros Ualisson N. Nascimento Carla R.P. Oliveira Daniela F. Cardoso Valdinaldo A. Melo Manuel H. Aguiar-Oliveira 《Journal of voice》2012,26(5):673.e13-673.e19
943.
When a high voltage is applied on an asymmetric capacitor, it experiences a force acting toward its thinner electrode. This effect is called Brown–Biefeld effect (BB), after its discoverers Thomas Townsend Brown and Paul Alfred Biefeld. Many theories have been proposed to explain this effect, and many speculations can be found on the net suggesting the effect is an antigravitation or a space warp effect. However, in the recent years, more and more researchers attribute the BB effect to a unicharge ion wind. This work calculates the levitation force due to ion wind and presents experimental results which confirm the theoretical results. 相似文献
944.
Daniela Fell Ngamjarassrivichai Pawanrat Elmar Bonaccurso Hans-Jürgen Butt Günter K. Auernhammer 《Colloid and polymer science》2013,291(2):361-366
The influence of local and nonlocal transport processes of cetyltrimethylammonium bromide (CTAB) molecules on dynamic contact angles and contact angle hysteresis was studied in a rotating drum setup. The influence of long-range surfactant transport was analyzed by hindering selectively the surface or the bulk transport via movable barriers. With increasing hindrance of the surfactant transport, the receding contact angle decreased at all withdrawing velocities in the presence of CTAB. The control experiment with pure water was unaffected by the presence of the barriers. Dynamic contact angles are, therefore, not only influenced by short-range effects like Marangoni stresses close to the contact line, but also by long-range transport processes (like diffusion and advection) between the regions close to the receding and advancing contact lines. 相似文献
945.
946.
Paolo Bonomi Paola Cairoli Daniela Ubiali Carlo F. Morelli Marco Filice Ines Nieto Massimo Pregnolato Paolo Manitto Marco Terreni Giovanna Speranza 《Tetrahedron: Asymmetry》2009,20(4):467-472
(R)-2-Tetralol (R)-2a, (R)-5-hydroxy-2-tetralol (R)-2b and (R)-8-hydroxy-2-tetralol (R)-2c, which are key intermediates in the synthesis of pharmacologically active 2-aminotetralins 3, were prepared in moderate to very high enantiomeric excess (up to 99% ee) by enzymatic resolution of the corresponding racemic butyrates rac-1a, rac-1b and rac-1c, respectively, using lipases immobilized on octyl agarose. This methodology is an alternative to the microbial reduction of 2-tetralones. 相似文献
947.
Claudia Gordin Christelle Delaite Sophie Bistac Anne-Sophie Schuller Daniela Rusu Mihai Rusu 《Polymer Testing》2009,28(4):446-451
Films composed of poly(vinyl chloride)/poly(?-caprolactone)/poly(?-caprolactone)-b-poly(dimethylsiloxane) [PVC/PCL/(PCL-b-PDMS)] blends were prepared by solvent casting from tetrahydrofuran. The PVC content was kept constant (60 wt %) while varying the PCL and PCL-b-PDMS contents, part of the PCL (0–20 wt %) in the PVC/PCL (60/40) blend being replaced with PCL-b-PDMS with different molecular weights of the PCL blocks. The prepared blends were investigated by infrared spectroscopy and contact angle measurements. FTIR analysis and contact angle measurements indicate that the PDMS blocks tend to migrate towards the surface and this migration is preferential to the side in contact with air. 相似文献
948.
Daniela ŠponarovÁ Daniel Horák 《Journal of polymer science. Part A, Polymer chemistry》2008,46(18):6263-6271
Poly(N,N‐diethylacrylamide)‐based microspheres were prepared by ammonium persulfate (APS)‐initiated and poly(vinylpyrrolidone) (PVP)‐stabilized dispersion polymerization. The effects of various polymerization parameters, including concentration of N,N′‐methylenebisacrylamide (MBAAm) crosslinker, monomer, initiator, stabilizer and polymerization temperature on their properties were elucidated. The hydrogel microspheres were described in terms of their size and size distribution and morphological and temperature‐induced swelling properties. While scanning electron microscopy was used to characterize the morphology of the microspheres, the temperature sensitivity of the microspheres was demonstrated by dynamic light scattering. The hydrodynamic particle diameter decreased sharply as the temperature reached a critical temperature ~ 30 °C. A decrease in the particle size was observed with increasing concentration of both the APS initiator and the PVP stabilizer. The microspheres crosslinked with 2–15 wt % of MBAAm had a fairly narrow size distribution. It was found that the higher the content of the crosslinking agent, the lower the swelling ratio. High concentration of the crosslinker gave unstable dispersions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6263–6271, 2008 相似文献
949.
Wolfgang Holzer Gernot A. Eller Barbara Datterl Daniela Habicht 《Magnetic resonance in chemistry : MRC》2009,47(7):617-624
NMR spectroscopic studies are undertaken with derivatives of 2‐pyrazinecarboxylic acid. Complete and unambiguous assignment of chemical shifts (1H, 13C, 15N) and coupling constants (1H,1H; 13C,1H; 15N,1H) is achieved by combined application of various 1D and 2D NMR spectroscopic techniques. Unequivocal mapping of 13C,1H spin coupling constants is accomplished by 2D (δ,J) long‐range INEPT spectra with selective excitation. Phenomena such as the tautomerism of 3‐hydroxy‐2‐pyrazinecarboxylic acid are discussed. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
950.
We construct infinite highly arc-transitive digraphs with finite out-valency and whose sets of descendants are digraphs which
have a homomorphism onto a directed (rooted) tree. Some of these constructions are based on [4] and [5], and are shown to
have universal reachability relation. 相似文献