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991.
Rafael Muñoz-Espí Clemens K. Weiss Katharina Landfester 《Current Opinion in Colloid & Interface Science》2012,17(4):212-224
The defined synthesis of inorganic nanoparticles is the crucial step for their successful application. Thus, preparation methods to control composition, shape, size, and aggregation behavior are of high interest and relevance. Here, the possibilities that the miniemulsion technique offers for the generation of inorganic nanoparticles are reviewed. Several of the traditional synthetic methods as the controlled precipitation or sol–gel chemistry were confined to the droplets of a miniemulsion, leading to new structures and morphologies. Furthermore, the focus is put on polymer- and latex-assisted mineralization and a miniemulsion-based approach to nonconventional colloidal lithography. 相似文献
992.
Belén Jiménez M Alcázar V Peláez R Sanz F Fuentes de Arriba AL Caballero MC 《Organic & biomolecular chemistry》2012,10(6):1181-1185
Urea receptor 1 based on two (1-amino-8-amido-3,6-dichloro)carbazole units shows a strong association with dicarboxylate anions such as oxalate, malonate and succinate guests through multiple hydrogen bonds from the carbazole, urea and amide NH groups. (1)H NMR complexation studies exhibit high values of association constants in DMSO-d(6). X-ray structures of the 1?:?1 complexes of 1 with oxalate and malonate as their ditetrabutylammonium salts were obtained. A modelling study of the complex of receptor 1 with succinate (as its diTBA salt) showed a more reduced geometric complementarity than its homologue malonate. 相似文献
993.
An impregnated copper on magnetite catalyst is a versatile system for different domino Sonogashira-cyclization processes between 2-iodophenol and different alkynes to give the corresponding substituted benzo[b]furans. The catalyst could be recovered ten times without losing its activity. The related process using 2-iodoaniline was, however, better catalyzed by mixed palladium–copper on magnetite giving exclusively, in this case, the products arising from the Sonogashira coupling. The cyclization to the corresponding substituted indoles could be easily and quantitatively performed by zinc bromide treatment. This catalyst avoids the use of any type of expensive and difficult to handle organic ligand, showing excellent yields, under mild reaction conditions. The catalyst is very easy to remove from the reaction medium, just by using a simple magnet. 相似文献
994.
Paula Ortega Silvia Moreno Mª Pilar Tarazona Fco. Javier de la Mata Rafael Gómez Ramirez 《European Polymer Journal》2012,48(8):1413-1421
New hyperbranched polymers based on a carbosiloxane–carbosilane skeleton with aromatic units in the backbone have been prepared via one-pot hydrosilylation reaction using HSi(Me)2–O–CH2–C6H4–OSiMe–(CH2)4(C3H5)2 as a novel AB2 monomer. These polymers are easy to prepare, have narrow polydispersity values and present allyl groups on the surface which can be used as synthetic platforms for the introduction of different terminal groups like amine groups through hydrosilylation reactions, opening the door to functionalized polymers. The polymerization process was monitored using real-time 1H NMR spectroscopy and the resulting hyperbranched polymers were characterized using 1H NMR, 13C NMR, 29Si NMR and SEC/MALLS. The degree of branching in these polymers was determined by quantitative 29Si NMR spectroscopy and found to be very close to the theoretical value of 0.50 for AB2 systems. The hydrolytic degradation of these polymers in protic solvents has been studied by 29Si NMR. 相似文献
995.
Cellet TS Guilherme MR Silva R Pereira GM Mauricio MR Muniz EC Rubira AF 《Journal of colloid and interface science》2012,367(1):494-501
Thermosensitive surfaces were developed by the grafting of a thin layer of PNIPAAm through an UV-induced photopolymerization reaction of vinyl monomers with a free radical-activated polypropylene (PP) surface. PNIPAAm layer covering the PP surface corrected, to some extension, both depressions and fissures of the previously modified PP surfaces. The layered surfaces have morphological characteristic different from those of the non-layered surfaces, and their thickness was dependent on irradiation time. Water contact angles of the layered surfaces revealed a transition at approximately 33.5-36.5 °C as a result of a response to the variation of temperature. There was an increase in the values of the contact angles with an increase in temperature from 26 °C to 44 °C, revealing the nature both hydrophilic and hydrophobic of the surfaces due to a conformational rearrangement of PNIPAAm exposing its isopropyl groups to the liquid drop. This work offers a chemically stable thermosensitive surface (because it is covalently structured) with great potential for use as sensors and actuators. 相似文献
996.
López-Castro JD Delgado JJ Perez-Omil JA Gálvez N Cuesta R Watt RK Domínguez-Vera JM 《Dalton transactions (Cambridge, England : 2003)》2012,41(4):1320-1324
An electron microscopy study, in combination with modeling and image simulation, of four different reconstituted ferritin samples: recombinant human H and L homopolymers, and H and L heteropolymers of native L-subunit-rich horse spleen and H-subunit-rich human heart ferritins, points out the existence of a correlation between iron core shape and protein shell. 相似文献
997.
García-Ramos JC Toledano-Magaña Y Talavera-Contreras LG Flores-Álamo M Ramírez-Delgado V Morales-León E Ortiz-Frade L Gutiérrez AG Vázquez-Aguirre A Mejía C Carrero JC Laclette JP Moreno-Esparza R Ruiz-Azuara L 《Dalton transactions (Cambridge, England : 2003)》2012,41(34):10164-10174
A new synthetic pathway was reported to obtain N6 donor ligand 2,9-bis-(2',5'-diazahexanyl)-1,10-phenanthroline (L1) and its coordination compounds of essential divalent metal ions Mn, Fe, Co, Ni, Cu and Zn. Complete characterization of all compounds was done with the conventional techniques. Crystal structures of [NiL1](PF(6))(2) and [ZnL1](PF(6))(2)·H(2)O were also reported. Electrochemical studies have shown an active participation of the aromatic moiety of the ligand in redox reactions. The in vitro tests of the cytotoxic activity against human tumour cell lines HeLa (cervix) and CHP-212 (neuroblastoma) showed that all coordination compounds that involve redox active metal ions exhibit noteworthy antiproliferative activity, superior in all cases to cisplatin. [CuL1](2+) showed the lower IC(50) value in the HeLa cell line with 1.84 μM, meanwhile, [CoL1](2+) showed the lower value in neuroblastoma CHP-212 with IC(50) = 45.28 μM. None of these compounds were active against the SK-N-SH neuroblastoma cell line. In Entamoeba histolytica cultures, remarkable nanomolar IC(50) values were found for [NiL1](2+) and [MnL1](2+) with 60 nM and 80 nM respectively, improving the antiproliferative activity more than 1000 times compared with the first choice drug for clinical treatments of human amoebiasis, metronidazole. On the other hand, a free ligand does not show antiproliferative activity either on human tumor cell lines or on Entamoeba histolytica trophozoites, highlighting the role played by metal ions to produce cytotoxicity in tumor cells and protozoa systems. 相似文献
998.
PA Bouit M Marszalek R Humphry-Baker R Viruela E Ortí SM Zakeeruddin M Grätzel JL Delgado N Martín 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(37):11621-11629
Two donor-acceptor molecular tweezers incorporating the 10-(1,3-dithiol-2-ylidene)anthracene unit as donor group and two cyanoacrylic units as accepting/anchoring groups are reported as metal-free sensitizers for dye-sensitized solar cells. By changing the phenyl spacer with 3,4-ethylenedioxythiophene (EDOT) units, the absorption spectrum of the sensitizer is red-shifted with a corresponding increase in the molar absorptivity. Density functional calculations confirmed the intramolecular charge-transfer nature of the lowest-energy absorption bands. The new dyes are highly distorted from planarity and are bound to the TiO(2) surface through the two anchoring groups in a unidentate binding form. A power-conversion efficiency of 3.7?% was obtained with a volatile CH(3) CN-based electrolyte, under air mass 1.5 global sunlight. Photovoltage decay transients and ATR-FTIR measurements allowed us to understand the photovoltaic performance, as well as the surface binding, of these new sensitizers. 相似文献
999.
Melts of CPs, intentionally contaminated with small fractions of LPs, are studied using the bond fluctuation model to probe the extreme sensitivity of the rheology to trace amounts of linear chains. Using primitive path analysis to compute the number of entanglements on the molecules, the threshold concentration at which LPs percolate through the system is calculated using a mean‐field theory. It is found that the percolation threshold decreases with the molecular weight, and is approximately 25–30 times smaller than the overlap concentration of the linear chains for the longest polymers studied. These simulations help to understand and justify the approximations made in earlier theoretical investigations.
1000.
Velitchkova M Yruela I Alfonso M Alonso PJ Picorel R 《Journal of photochemistry and photobiology. B, Biology》2003,69(1):41-48
Photoinactivation kinetics of photosystem I (PSI)-mediated electron transport rate was compared to that of P700 content at room (22 degrees C) and low (4 degrees C) temperatures in isolated spinach thylakoid membranes. The high light treatment was carried out under aerobic and anaerobic conditions. At 22 degrees C the decrease of electron transport rate showed first order exponential kinetics. The amount of P700 decreased linearly, being less affected in the first hours of illumination. During photoinhibition at 4 degrees C in the presence of oxygen, the kinetics of inactivation of PSI photochemical activity and the content of P700 were different. It was found that 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) had different protective effect on the electron transport rate and on P700 content at both temperatures. Treatment with high light intensity under N(2) atmosphere had no effect on the electron transport rate or P700 content. The possible degradation of PSI reaction centre proteins was determined using immunoblot methods. In the presence of linear electron transport at 22 degrees C correlation between formation of toxic hydroxyl radicals and inhibition of oxygen uptake was observed. 相似文献