排序方式: 共有61条查询结果,搜索用时 15 毫秒
51.
Dr. Marta Perez-Lloret Dr. Aurore Fraix Dr. Salvatore Petralia Dr. Sabrina Conoci Dr. Virginie Tafani Dr. Giovanna Cutrone Prof. Antonio Vargas-Berenguel Dr. Ruxandra Gref Prof. Salvatore Sortino 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(64):14638-14643
A simple and green synthetic protocol for the rapid and effective preparation of Ag, Au and Au@Ag core–shell nanoparticles (NPs) is reported based on the light irradiation of a biocompatible, water-soluble dextran functionalized with benzophenone (BP) in the presence of AgNO3, HAuCl4, or both. Photoactivation of the BP moiety produces the highly reducing ketyl radicals through fast (<50 ns) intramolecular H-abstraction from the dextran scaffold, which, in turn, ensures excellent dispersibility of the obtained metal NPs in water. The antibacterial activity of the AgNPs and the photothermal action of the Au@Ag core–shell are also shown. 相似文献
52.
Alexandra-Elisabeta Stamate Rodica Zvoianu Octavian Dumitru Pavel Ruxandra Birjega Andreea Matei Marius Dumitru Ioana Brezetean Mariana Osiac Ioan-Cezar Marcu 《Molecules (Basel, Switzerland)》2021,26(20)
Mechanical activation and mechanochemical reactions are the subjects of mechanochemistry, a special branch of chemistry studied intensively since the 19th century. Herein, we comparably describe two synthesis methods used to obtain the following layered double hydroxide doped with cerium, Mg3Al0.75Ce0.25(OH)8(CO3)0.5·2H2O: the mechanochemical route and the co-precipitation method, respectively. The influence of the preparation method on the physico-chemical properties as determined by multiple techniques such as XRD, SEM, EDS, XPS, DRIFT, RAMAN, DR-UV-VIS, basicity, acidity, real/bulk densities, and BET measurements was also analyzed. The obtained samples, abbreviated HTCe-PP (prepared by co-precipitation) and HTCe-MC (prepared by mechanochemical method), and their corresponding mixed oxides, Ce-PP (resulting from HTCe-PP) and Ce-MC (resulting from HTCe-MC), were used as base catalysts in the self-condensation reaction of cyclohexanone and two Claisen–Schmidt condensations, which involve the reaction between an aromatic aldehyde and a ketone, at different molar ratios to synthesize compounds with significant biologic activity from the flavonoid family, namely chalcone (1,3-diphenyl-2-propen-1-one) and flavone (2-phenyl-4H-1benzoxiran-4-one). The mechanochemical route was shown to have indisputable advantages over the co-precipitation method for both the catalytic activity of the solids and the costs. 相似文献
53.
Dr. Ruxandra Maria Ilie-Mihai Sorin Sebastian Gheorghe Prof. Dr. habil. Raluca-Ioana Stefan-van Staden Alexandru Bratei 《Electroanalysis》2021,33(1):6-10
Interleukins proved to be valuable biomarkers for different diseases. Interleukins 1β, 6, and 12 can be used as biomarkers for brain cancer diagnosis, and therefore this paper proposed a needle stochastic sensor based on protoporphyrin IX immobilized in nanodiamond paste for fast screening of biological samples such as whole blood, urine and brain tumoral tissue for these interleukins. The results obtained using this needle stochastic sensor proved that the interleukins 1β, 6, and 12 can be reliable determined from whole blood, urine and brain tumoral tissue, with recoveries higher than 96.00 %, with relative standard deviations lower than 1.00 %. 相似文献
54.
Georgeta Voicu Ruxandra E. Geanaliu Cristina D. Ghiţulică Anton Ficai Alexandru M. Grumezescu Coralia Bleotu 《Central European Journal of Chemistry》2013,11(12):2134-2143
The purpose of the present study is the preparation and characterization of collagen/antitumor drug hybrids as drug delivery systems. Materials used for obtaining collagen-based drug delivery systems were collagen type I (Coll) as matrix and irinotecan (I) as hydrophilic active substances. After incorporation of I into Coll in differing ratios, the obtained hybrid materials (Coll/I) could be used according to our results as potential drug delivery systems in medicine for the topical (local) treatment of cancerous tissues or bone. The released amount of I varies with amount of Coll from hybrid materials: the higher, the slower the release amount of irinotecan transferred is in the first 6 hours. The in vitro citotoxicity demonstrates an antitumoral activity of the obtained hybrid materials and their potential use for biomedical applications as drug delivery systems in tumoral treatments. 相似文献
55.
Rodica Zăvoianu Ruxandra Bîrjega Emilian Angelescu Octavian D. Pavel 《Comptes Rendus Chimie》2018,21(3-4):318-326
This contribution investigates the obtaining of layered double hydroxides (LDHs) modified with different concentrations of yttrium and the effect of the yttrium concentration and temperature during the rehydration of the mixed oxides derived from these solids. Mg3Al(1?x)Yx-LDH (where x = 0.04–0.6) have been prepared using the standard coprecipitation method under low supersaturation conditions. After the calcination of these solids (460 °C, 18 h), the corresponding mixed oxides were obtained. The reconstruction of the layered structure was attempted by rehydration of the mixed oxides under two different conditions: (1) at 25 °C and (2) at 70 °C. All the aforementioned solids have been characterized by chemical analysis, X-ray diffraction, DRIFTS spectra, N2 adsorption–desorption isotherms, and determination of base sites. Their catalytic activity was tested in cyanoethylation of ethanol with acrylonitrile. The results obtained after the characterization and the catalytic activity tests were compared with those obtained for a standard hydrotalcite Mg3Al. 相似文献
56.
Dr. Erhan Deniz Noufal Kandoth Dr. Aurore Fraix Dr. Venera Cardile Dr. Adriana C. E. Graziano Dr. Debora Lo Furno Dr. Ruxandra Gref Prof. Françisco M. Raymo Prof. Salvatore Sortino 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(49):15782-15787
A viable strategy to encapsulate a fluorophore/photochrome dyad and a nitric oxide photodonor within supramolecular assemblies of a cyclodextrin‐based polymer in water was developed. The two photoresponsive guests do not interact with each other within their supramolecular container and can be operated in parallel under optical control. Specifically, the dyad permits the reversible switching of fluorescence on a microsecond timescale for hundreds of cycles, and the photodonor enables the irreversible release of nitric oxide. Furthermore, these supramolecular assemblies cross the membrane of human melanoma cancer cells and transport their cargo in the cytosol. The fluorescence of one component allows the visualization of the labeled cells, and its switchable character could, in principle, be used to acquire super‐resolution images, while the release of nitric oxide from the other induces significant cell mortality. Thus, our design logic for the construction of biocompatible nanoparticles with dual functionality might evolve into the realization of valuable photoresponsive probes for imaging and therapeutic applications. 相似文献
57.
Determination of sizes and flexibilities of RNA molecules is important in understanding the nature of packing in folded structures and in elucidating interactions between RNA and DNA or proteins. Using the coordinates of the structures of RNA in the Protein Data Bank we find that the size of the folded RNA structures, measured using the radius of gyration R(G), follows the Flory scaling law, namely, R(G)=5.5N(1/3) A, where N is the number of nucleotides. The shape of RNA molecules is characterized by the asphericity Delta and the shape S parameters that are computed using the eigenvalues of the moment of inertia tensor. From the distribution of Delta, we find that a large fraction of folded RNA structures are aspherical and the distribution of S values shows that RNA molecules are prolate (S>0). The flexibility of folded structures is characterized by the persistence length l(p). By fitting the distance distribution function P(r), that is computed using the coordinates of the folded RNA, to the wormlike chain model we extracted the persistence length l(p). We find that l(p) approximately 1.5N(0.33) A which might reflect the large separation between the free energies that stabilize secondary and tertiary structures. The dependence of l(p) on N implies that the average length of helices should increase as the size of RNA grows. We also analyze packing in the structures of ribosomes (30S, 50S, and 70S) in terms of R(G), Delta, S, and l(p). The 70S and the 50S subunits are more spherical compared to most RNA molecules. The globularity in 50S is due to the presence of an unusually large number (compared to 30S subunit) of small helices that are stitched together by bulges and loops. Comparison of the shapes of the intact 70S ribosome and the constituent particles suggests that folding of the individual molecules might occur prior to assembly. 相似文献
58.
Time dependent, cathodic electrodeposition of ultrathin CdTe and Te films has been studied in 50 mM H(2)SO(4) + 1 mM CdSO(4) + 0.1 mM TeO(2) solutions at room temperature under potential control using electrochemical atomic force microscopy (EC-AFM). The films were also characterized electrochemically and with X-ray diffraction. The growth mechanism and the composition of the films depends on the applied potentials. Island-like growth mode was observed for CdTe films when the deposition potential was -0.35 V (SHE). At a more positive deposition potential of 0.138 V (SHE), Cd was not co-deposited into the film but affected the dynamic growth mode of the deposit. At this voltage smooth Te films were obtained. Depending on the applied potential, Cd acts either as a co-deposition element for CdTe film growth, or as a mediator for layer-by-layer growth of Te films. 相似文献
59.
The objective of this paper is to describe a methodology to design control laws in the context of a computational aeroelasticity environment. The technical approach involves employing a systems identification technique to develop an explicit state-space model for control law design from the output of a computational aeroelasticity code. As a control law design techniques, the standard LQG technique is employed. The computational aeroelasticity code is modified to accept control laws and perform closed-loop simulations. Numerical results for flutter suppression of the BACT wind-tunnel model are given. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
60.
Vasile?Br?nz?nescuEmail author Ruxandra?Moraru 《Communications in Mathematical Physics》2005,254(3):565-580
In this paper, we study the moduli spaces of stable rank-2 vector bundles on non-Kähler elliptic surfaces, thus giving a classification of these bundles; in the case of Hopf and Kodaira surfaces, these moduli spaces admit the structure of an algebraically completely integrable Hamiltonian system.The first author was partially supported by Swiss NSF contract SCOPES 2000-2003, No.7 IP 62615 and by contract CERES 39/2002–2004.Acknowledgement The first author would like to express his gratitude to the Max Planck Institute of Mathematics for its hospitality and stimulating atmosphere; part of this paper was prepared during his stay at the Institute. The second author would like to thank Jacques Hurtubise for his generous encouragement and support during the completion of this paper; she would also like to thank Ron Donagi and Tony Pantev for valuable discussions, and the Department of Mathematics at the University of Pennsylvania for their hospitality, during the preparation of part of this article. 相似文献