排序方式: 共有23条查询结果,搜索用时 31 毫秒
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Hanna C. Wentz Grigorii Skorupskii Ana B. Bonfim Jenna L. Mancuso Christopher H. Hendon Evan H. Oriel Graham T. Sazama Michael G. Campbell 《Chemical science》2020,11(5):1342
Redox-active metal–organic frameworks (MOFs) are promising materials for a number of next-generation technologies, and recent work has shown that redox manipulation can dramatically enhance electrical conductivity in MOFs. However, ligand-based strategies for controlling conductivity remain under-developed, particularly those that make use of reversible redox processes. Here we report the first use of ligand n-doping to engender electrical conductivity in a porous 3D MOF, leading to tunable conductivity values that span over six orders of magnitude. Moreover, this work represents the first example of redox switching leading to reversible conductivity changes in a 3D MOF.Redox-active ligands are used to reversibly tune electrical conductivity in a porous 3D metal–organic framework (MOF). 相似文献
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do Nascimento Marreiro Teixeira Ana Siqueira Siqueira Teixeira Paulo Ronaldo Sousa de Oliveira Farias Emanuel Airton Ferraz e Sousa Brandon Moura Sérvulo Kátia Bonfim de Leite da Silva Durcilene Alves Eiras Carla 《Journal of Solid State Electrochemistry》2020,24(5):1143-1155
Journal of Solid State Electrochemistry - The present work proposes a new electrochemical sulfite biosensor based on babassu mesocarp nanoparticles (BMNPs) immobilized on the surface of a pyrolytic... 相似文献
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Bonfim M Ghiringhelli G Montaigne F Pizzini S Brookes NB Petroff F Vogel J Camarero J Fontaine A 《Physical review letters》2001,86(16):3646-3649
We have developed a new original technique to study the magnetization reversal dynamics of thin films with element selectivity in the nanosecond time scale. X-ray magnetic circular dichroism measurements in pump-probe mode are carried out taking advantage of the time structure of synchrotron radiation. The dynamics of the magnetization reversal of each of the layers of complex heterostructures (like spin valves or tunnel junctions) can be probed independently. The interlayer coupling in the studied systems has been shown to play a key role in the determination of the magnetization reversal of each individual layer. 相似文献
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Fukumoto K Kuch W Vogel J Romanens F Pizzini S Camarero J Bonfim M Kirschner J 《Physical review letters》2006,96(9):097204
The dynamics of magnetic domain wall motion in the FeNi layer of a FeNi/Al2O3/Co trilayer has been investigated by a combination of x-ray magnetic circular dichroism, photoelectron emission microscopy, and a stroboscopic pump-probe technique. The nucleation of domains and subsequent expansion by domain wall motion in the FeNi layer during nanosecond-long magnetic field pulses was observed in the viscous regime up to the Walker limit field. We attribute an observed delay of domain expansion to the influence of the domain wall energy that acts against the domain expansion and that plays an important role when domains are small. 相似文献
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Magnetoelectric experiments provide information on spin configurations, critical indices and microscopic ionic interactions. The basic theory of the magnetoelectric effect in antiferromagnets is rederived in this article and extended to situations in which there is an external magnetic field including the spin-flop phase. It is found that measurements of the magnetoelectric tensor α as a function of field in the antiferromagnetic and spin-flop phases of an antiferromagnet can provide more complete information in all three categories above. Certain higher-order terms are examined and it is found that it is possible to measure the staggered susceptibility directly in magnetoelectric materials. It is shown that a non-zero value of α causes a tetragonal antiferromagnet to be optically biaxial. A pedagogical discussion of the origins of magnetoelectric effects is given in the Appendix. 相似文献
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César IC Byrro RM de Santana E Silva Cardoso FF Mundim IM de Souza Teixeira L Rezende KR da Silva EP Gomes SA de Sousa VA Bonfim RR Pianetti GA 《Biomedical chromatography : BMC》2012,26(7):851-856
A rapid method for the quantification of glucosamine in human plasma using high‐performance liquid chromatography coupled to tandem mass spectrometry was developed and validated. The sample preparation includes a simple deproteinization step, using d ‐[1‐13C] glucosamine hydrochloride as an internal standard. Chromatographic separation was performed on an ACE Ciano column using isocratic elution with acetonitrile and aqueous 2 mm ammonium acetate containing 0.025% formic acid (80:20). Selected reaction monitoring was performed using the transitions m/z 180.1 → m/z 72.1 and m/z 181.0 → m/z 74.6 to quantify glucosamine and internal standard, respectively. The method was validated and proved to be linear, accurate and precise over the range 50–5000 ng/mL of glucosamine. Recovery rates higher than 90% were obtained for both glucosamine and internal standard. No matrix effect was detected in the samples. The validated method was successfully applied to a pharmacokinetic study after oral administration of a powder for oral solution formulation containing glucosamine sulfate. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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Camarero J Pennec Y Vogel J Bonfim M Pizzini S Ernult F Fettar F Garcia F Lançon F Billard L Dieny B Tagliaferri A Brookes NB 《Physical review letters》2003,91(2):027201
An in-plane perpendicular magnetic coupling between Ni80Fe20 and Co has been found in NiFe/NiO/Co trilayers for a NiO thickness ranging from 4 to 25 nm by magneto-optical Kerr effect and x-ray magnetic circular dichroism measurements. In the easy magnetization direction of the Co layer, the Co coercive field H(C) increases when the thickness of the NiO layer t(NiO) increases. Because of the coupling, H(C) is always larger than for NiO/Co bilayers with the same thicknesses. The saturation field of the NiFe layer H(S) decreases when t(NiO) increases, indicating a weakening of the coupling. Numerical simulations show that the presence of interface roughness combined with a small value of the NiO anisotropy can explain the observed 90 degrees coupling. 相似文献
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O. F. de Alcantara Bonfim 《Journal of statistical physics》1991,62(1-2):105-115
The three-state Potts model in three dimensions is studied by Monte Carlo and finite-size scaling techniques. Using a histogram method recently proposed by Ferrenberg and Swendsen, the finite-size dependence for the maximum of the specific heat is found to scale with the volume of the system, indicating that the phase transition is of first order. The value of the latent heat per spin and the correlation length at the transition are estimated. 相似文献
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Bromelain Enzyme from Pineapple: In Vitro Activity Study under Different Micropropagation Conditions
Jaci Lima Vilanova Neta Ana da Silva Lédo Aloisio André Bonfim Lima José Carlos Curvelo Santana Nadjma Souza Leite Denise Santos Ruzene Daniel Pereira Silva Roberto Rodrigues de Souza 《Applied biochemistry and biotechnology》2012,168(2):234-246
The aim of this work was to evaluate the activity of bromelain in pineapple plants (Ananas comosus var. Comosus), Pérola cultivar, produced in vitro in different culture conditions. This enzyme, besides its pharmacological effects, is also employed in food industries, such as breweries and meat processing. In this work, the enzymatic activity was evaluated in the tissues of leaves and stems of plants grown in culture medium without plant growth regulator. The most significant levels of bromelain were observed in leaf tissue after 4?months of culture in vitro in medium with a filter paper bridge, followed by medium gelled by the agar. The results of this study, regarding the different structures of the pineapple (leaves and stems) in vitro showed that the activity of bromelain varied depending on the culture conditions, the time and structure of which was quantified, ensuring a viable strategy in the production of seedlings with high levels of bromelain in subsequent phases of micropropagation. 相似文献