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21.
H. Brito-Santana R. Rodríguez-Ramos R. Guinovart-Díaz J. Bravo-Castillero F. J. Sabina G. A. Maugin 《Archive of Applied Mechanics (Ingenieur Archiv)》2009,79(3):189-204
Using the spherical and deviator decomposition of the polarization and strain tensors, we present a general algorithm for
the calculation of variational bounds of dimension d for any type of anisotropic linear elastic composite as a function of the properties of the comparison body. This procedure
is applied in order to obtain analytical expressions of bounds for multiphase, linear elastic composites with cubic symmetry
where the geometric shapes of the inclusions are arbitrary. For the validation, it can be proved that for the isotropic particular
case, the bounds coincide with those recently reported by Gibiansky and Sigmund. On the other hand, based on this general
procedure some, classical bounds reported by Hashin for transversely isotropic composites, are reproduced. Numerical calculations
and some comparisons with other models and experimental data are shown. 相似文献
22.
A pore-scale analysis of nonaqueous phase liquid (NAPL) blob dissolution and mobilization in porous media was presented. Dissolution
kinetics of residual NAPLs in an otherwise water-saturated porous medium was investigated by conducting micromodel experiments.
Changes in residual NAPL volume were measured from recorded video images to calculate the mass transfer coefficient, K and the lumped mass transfer rate coefficient, k. The morphological characteristics of the blobs such as specific and intrinsic area were found to be independent of water
flow rate except at NAPL saturations below 2%. Dissolution process was also investigated by separating the mass transfer into
zones of mobile and immobile water. The fractions of total residual NAPL perimeters in contact with mobile water and immobile
water were measured and their relationship to the mass transfer coefficient was discussed. In general, residual NAPLs are
removed by dissolution and mobilization. Although these two mechanisms were studied individually by others, their simultaneous
occurrence was not considered. Therefore, in this study, mobilization of dissolving NAPL blobs was investigated by an analysis
of the forces acting on a trapped NAPL blob. A dimensional analysis was performed to quantify the residual blob mobilization
in terms of dimensionless Capillary number (Ca
I). If Ca
I is equal to or greater than the trapping number defined as , then blob mobilization is expected. 相似文献
23.
Min Tu Helge Reinsch Sabina Rodríguez‐Hermida Rhea Verbeke Timothe Stassin Werner Egger Marcel Dickmann Bjorn Dieu Johan Hofkens Ivo F. J. Vankelecom Norbert Stock Rob Ameloot 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2445-2449
Metal–organic frameworks (MOFs) enable the design of host–guest systems with specific properties. In this work, we show how the confinement of anthracene in a well‐chosen MOF host leads to reversible yellow‐to‐purple photoswitching of the fluorescence emission. This behavior has not been observed before for anthracene, either in pure form or adsorbed in other porous hosts. The photoresponse of the host–guest system is caused by the photodimerization of anthracene, which is greatly facilitated by the pore geometry, connectivity, and volume as well as the structural flexibility of the MOF host. The photoswitching behavior was used to fabricate photopatternable and erasable surfaces that, in combination with data encryption and decryption, hold promise in product authentication and secure communication applications. 相似文献
24.
Fuxiang Ji Feng Wang Libor Kobera Sabina Abbrent Jiri Brus Weihua Ning Feng Gao 《Chemical science》2021,12(5):1730
Although lead-free halide double perovskites are considered as promising alternatives to lead halide perovskites for optoelectronic applications, state-of-the-art double perovskites are limited by their large bandgap. The doping/alloying strategy, key to bandgap engineering in traditional semiconductors, has also been employed to tune the bandgap of halide double perovskites. However, this strategy has yet to generate new double perovskites with suitable bandgaps for practical applications, partially due to the lack of fundamental understanding of how the doping/alloying affects the atomic-level structure. Here, we take the benchmark double perovskite Cs2AgInCl6 as an example to reveal the atomic-level structure of double perovskite alloys (DPAs) Cs2AgIn1−xFexCl6 (x = 0–1) by employing solid-state nuclear magnetic resonance (ssNMR). The presence of paramagnetic alloying ions (e.g. Fe3+ in this case) in double perovskites makes it possible to investigate the nuclear relaxation times, providing a straightforward approach to understand the distribution of paramagnetic alloying ions. Our results indicate that paramagnetic Fe3+ replaces diamagnetic In3+ in the Cs2AgInCl6 lattice with the formation of [FeCl6]3−·[AgCl6]5− domains, which show different sizes and distribution modes in different alloying ratios. This work provides new insights into the atomic-level structure of bandgap engineered DPAs, which is of critical significance in developing efficient optoelectronic/spintronic devices.Through Fe3+-alloying, the bandgap of benchmark double perovskite Cs2AgInCl6 can be tuned from 2.8 eV to 1.6 eV. The atomic-level structure of Cs2AgIn1−xFexCl6 was revealed by solid-state nuclear magnetic resonance (ssNMR). 相似文献
25.
Soo Yeon Kim Arup Podder Hyunseung Lee Youn-Joo Cho Eun Hee Han Sabina Khatun Jonathan L. Sessler Kwan Soo Hong Sankarprasad Bhuniya 《Chemical science》2020,11(36):9875
Abnormal anaerobic metabolism leads to a lowering of the pH of many tumours, both within specific intracellular organelles and in the surrounding extracellular regions. Information relating to pH-fluctuations in cells and tissues could aid in the identification of neoplastic lesions and in understanding the determinants of carcinogenesis. Here we report an amphiphilic fluorescent pH probe (CS-1) that, as a result of its temporal motion, provides pH-related information in cancer cell membranes and selected intracellular organelles without the need for specific tumour targeting. Time-dependent cell imaging studies reveal that CS-1 localizes within the cancer cell-membrane about 20 min post-incubation. This is followed by migration to the lysosomes at 30 min before being taken up in the mitochondria after about 60 min. Probe CS-1 can selectively label cancer cells and 3D cancer spheroids and be readily observed using the green fluorescence channel (λem = 532 nm). In contrast, CS-1 only labels normal cells marginally, with relatively low Pearson''s correlation coefficients being found when co-incubated with standard intracellular organelle probes. Both in vivo and ex vivo experiments provide support for the suggestion that CS-1 acts as a fluorescent label for the periphery of tumours, an effect ascribed to proton-induced aggregation. A much lower response is seen for muscle and liver. Based on the present results, we propose that sensors such as CS-1 may have a role to play in the clinical and pathological detection of tumour tissues or serve as guiding aids for surgery.A self-assembled amphiphilic fluorescent probe allows pH-fluctuations within cancer cells and tumour tissues to be readily detected. 相似文献
26.
Gilbert Mercieca Sara Odoardi Serena Mestria Marisa Cassar Sabina Strano‐Rossi 《Journal of separation science》2020,43(14):2858-2868
The constant emergence of new psychoactive substances is a challenge to clinical and forensic toxicologists who need to constantly update analytical techniques to detect them. A large portion of these substances are synthetic cannabinoids. The aim of this study was to develop a rapid and simple method for the determination of synthetic cannabinoids and their metabolites in urine and blood using gas chromatography–mass spectrometry. The method involves an ultrasound‐assisted dispersive liquid–liquid microextraction that implies a rapid procedure, giving excellent extraction efficiencies with minimal use of toxic solvents. This is followed by silylation and analysis with gas chromatography–mass spectrometry. The chromatographic method allows for the separation and identification of 29 selected synthetic cannabinoids and some metabolites. The method was validated on urine and blood samples with the ability to detect and quantify all analytes with satisfactory limits of detection (from 1 to 5 ng/mL), limits of quantification (5 ng/mL), and selectivity and linearity (in the range of 5–200 ng/mL). The developed assay is highly applicable to laboratories with limited instrumental availability, due to the use of efficient and low‐cost sample preparation and instrumental equipment. The latter may contribute to enhance the detection of new psychoactive substances in clinical and forensic toxicology laboratories. 相似文献
27.
28.
Bravo-Castillero Julian; Rodriguez-Ramos Reinaldo; Mechkour Houari; Otero Jose A.; Sabina Federico J. 《The Quarterly Journal of Mechanics and Applied Mathematics》2008,61(3):311-332
In this work, based on the periodic unfolding homogenizationtechnique, the limiting equations modelling the behaviour ofthree-dimensional magneto-electro-elastic periodic structuresare rigorously established. The local problems and the correspondinghomogenized coefficients of the elastic, dielectric, magneticpermittivity, piezoelectric, piezomagnetic and magneto-electric(ME) tensors are explicitly described. The homogenization modelis exemplified for laminated composites and a unified generalformula for all effective properties of periodic multilaminatedmagneto-electro-elastic composites is obtained. This formulais applied to investigate the global behaviour for the importantcase of transversely isotropic constituents and any finite numberof layers in each periodic cell. Examples that provide theoreticalevidence of the presence of both a product property and theME effect are given. 相似文献
29.
Valerio Annovazzi-Lodi Giuseppe Aromataris Mauro Benedetti Michael Hamacher Sabina Merlo Valeria Vercesi 《Optical and Quantum Electronics》2010,42(3):143-156
In this paper, we numerically evaluate private data transmission using a three-laser scheme, consisting of a pair of twin
semiconductor lasers, driven to chaos by delayed optical feedback in a short cavity, and optically injected by a third chaotic
laser which forces them to synchronize. This laser is selected with different internal parameters with respect to the twin
pair, so that the emissions of the synchronized, matched lasers, are highly correlated, whereas their correlation with the
driver is low. The digital message modulates the emission of the transmitter, as in a standard Chaos Modulation scheme. Message
recovery is then obtained by subtracting, from the transmitted chaos-masked message, the chaos, locally generated by the synchronized
receiver laser. Simulations have been performed with the Lang-Kobayashi model, and, in view of application to private transmission,
we have investigated the effect of the parameter mismatch, between transmitter and receiver, on message recovery. A preliminary
experimental evaluation has been also performed using specially designed InP integrated modules. 相似文献
30.
Sabina Strano Rossi Xavier de la Torre Francesco Botrè 《Rapid communications in mass spectrometry : RCM》2010,24(10):1475-1480
A fast method has been developed for the simultaneous determination of 52 stimulants and narcotics excreted unconjugated in urine by gas chromatography/mass spectrometry (GC/MS). The procedure involves the liquid/liquid extraction of the analytes from urine at strong alkaline pH and the injection of the extract into a GC/MS instrument with a fast GC column (10 m × 0.18 mm i.d.); the short column allows the complete separation of the 52 analytes in a chromatographic run of 8 min. The method has been fully validated giving lower limits of detection (LLODs) satisfactory for its application to antidoping analysis as well as to forensic toxicology. The repeatability of the concentrations and the retention times are good both for intra‐ and for inter‐day experiments (%CV of concentrations always lower than 15 and %CV of retention times lower than 0.6). In addition, the analytical bias is satisfactory (A% always >15%). The method proposed here would be particularly useful whenever there are time constraints and the analyses have to be completed in the shortest possible time. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献