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1.
Luca Pasquini Elsa Callini Matteo Brighi Federico Boscherini Amelia Montone Torben R. Jensen Chiara Maurizio Marco Vittori Antisari Ennio Bonetti 《Journal of nanoparticle research》2011,13(11):5727-5737
We report on the hydrogen storage behaviour of Mg nanoparticles (NPs) (size range 100 nm–1 μm) with metal-oxide core–shell
morphology synthesized by inert gas condensation and decorated by transition metal (TM) (Pd or Ti) clusters via in situ vacuum
deposition. The structure and morphology of the as-prepared and hydrogenated NPs is studied by electron microscopy, X-ray
diffraction including in situ experiments and X-ray absorption spectroscopy, in order to investigate the relationships with
the hydrogen storage kinetics measured by the volumetric Sieverts method. With both Pd and Ti, the decoration deeply improves
the hydrogen sorption properties: previously inert NPs exhibit complete hydrogenation with fast transformation kinetics, good
stability and reversible gravimetric capacity that can attain 6 wt%. In the case of Pd-decoration, the occurrence of Mg–Pd
alloying is observed at high temperatures and in dependence of the hydrogen pressure conditions. These structural transformations
modify both the kinetics and thermodynamics of hydride formation, while Ti-decoration has an effect only on the kinetics.
The experimental results are discussed in relation with key issues such as the amount of decoration, the heat of mixing between
TM and Mg and the binding energy between TM and hydrogen. 相似文献
2.
José Gaspar Mihail Fontul Elsa Henriques António Ribeiro Arlindo Silva Nuno Valverde 《Applied Acoustics》2016
The car interior is becoming quieter and other sounds are now exposed to user perception, such as the sound produced by interface buttons when actuated. So, the functional role of the button sound on interface operation and its aesthetic and emotional role on the user experience are now more important than before. However, little research and design effort has been paid to understand how to design buttons that produce a pleasant sound. Moreover, the button’s sound requirements received by interface manufacturers are ill-defined, insufficient or even inexistent, and consequently their conversion into specifications for manufacturing is problematic and leads to long and costly development processes. The purpose of this paper is to contribute to identify relevant acoustic parameters that explain the users sound preferences. Data on preference subjective judgments were collected and buttons acoustic signals were measured allowing the development of preference models based on partial least squares regression and neural networks methods. The former was successful in selecting the relevant parameters to describe the preference ratings of the buttons sound. The later, dealing with the non-linear nature of acoustic perception, was able to predict preferences based on the relevant parameters. 相似文献
3.
Elsa Cortina Carlos E DAttellis 《Journal of Mathematical Analysis and Applications》1984,101(1):308-323
By a decomposition of L+2(Cn) in two orthogonal subspaces we obtain a representation of a matrix-valued function of the class Π, defined by Arov (Darlington realization of matrix-valued functions, Izv. Akad. Nauk. SSSR, Ser. Mat. Tom.37 (1973), No. 6); (Math. USSR Izvestija7 (1973), No. 6, 1295–1326). Real matrix-valued functions of this class play an important role in methods of synthesis of scattering matrices of linear passive n-ports. 相似文献
4.
5.
Henriques ES Floriano WB Reuter N Melo A Brown D Gomes JA Maigret B Nascimento MA Ramos MJ 《Journal of computer-aided molecular design》2001,15(4):309-322
We present the search for a new model of -factor XIIa, a blood coagulation enzyme, with an unknown experimental 3D-structure. We decided to build not one but three different models using different homologous proteins as well as different techniques and different modellers. Additional studies, including extensive molecular dynamics simulations on the solvated state, allowed us to draw several conclusions concerning homology modelling, in general, and -factor XIIa, in particular. 相似文献
6.
Elsa Gorre Cathy Muste Kevin G. Owens 《Journal of the American Society for Mass Spectrometry》2018,29(11):2248-2259
Matrix-assisted laser desorption ionization (MALDI) time-of-flight mass spectrometry (TOF MS) is now accepted as a quick, easy-to-use, cost-effective, and accurate technique for the identification of microorganisms. However, the successful identification of microorganisms is dependent upon careful attention to factors such as growth conditions, extraction methods, mass spectral data collection, and data analysis procedures. Currently, most microorganism identification has been limited to the species level, and only a limited number of publications have been successful in achieving strain-level identification. In this work, a “cell-free” approach is introduced where peptide analytes secreted by several Saccharomyces cerevisiae strains during their growth period are analyzed. The analysis of the cell supernatant generates mass spectral patterns that are specific to each strain. The patterns generated in combination with a robust data analysis workflow using the open-source programs MALDIquant and Mass-Up allows for strain-level identification of S. cerevisiae. The cell-free approach using the yeast supernatant to accurately identify yeast strains is presented here as a proof of concept. 相似文献
7.
The effects of addition of alkanols (ethanol, n-hexanol, and 3-ethyl-3-pentanol) on the micropolarity and microviscosity of the head group region in reverse micelles of AOT-heptane-water have been investigated by fluorescence probing methods (ANS fluorescence yield and TMADPH fluorescence anisotropy), complemented by the use of the solvatochromic probe E(T)(30) in absorption spectroscopy. For all the alkanols considered, ANS fluorescence in AOT reverse micelles (at W=3) is quenched by additive incorporation, being the effect elicited almost independent of the alkanol chain length and topology. As sensed by the E(T)(30) parameter, the micropolarity of the micelle surface increases, remains unmodified, and decreases upon addition of ethanol, 3-ethyl-3-pentanol, and hexanol, respectively. While ethanol barely modifies the fluorescence anisotropy of TMADPH, 3-ethyl-3-pentanol and n-hexanol addition strongly decrease it. The similarity of the tendencies of ANS data to TMADPH anisotropies and the differences between ANS data and E(T)(30) values would indicate that, at least for 3-ethyl-3-pentanol and n-hexanol, microviscosity, rather than micropolarity, must be considered to interpret the effect of the alkanols upon the fluorescent behavior of ANS. 相似文献
8.
Magnus Rogeberg Steven Ray WilsonTyge Greibrokk Elsa Lundanes 《Journal of chromatography. A》2010,1217(17):2782-2786
Porous layer open tubular (PLOT) polystyrene divinylbenzene columns have been used for separating intact proteins with gradient elution. The 10 μm I.D. × 3 m columns were easily coupled to standard liquid chromatography–mass spectrometry (LC–MS) instrumentation with commercially available fittings. Standard proteins separated on PLOT columns appeared as narrow and symmetrical peaks with good resolution. Average peak width increased linearly with gradient time (tG) from 0.14 to 0.33 min (tG 20 and 120 min, respectively) using a 3 m column. With shorter columns, peak widths were larger and increased more steeply with gradient time. Theoretical peak capacity (nc) increased with column length (tested up to 3 m). The nc increased with tG until a plateau was reached. The highest peak capacity achieved (nc = 185) was obtained with a 3 m column, where a plateau was reached with tG 90 min. The within- and between column retention time repeatabilities were below 0.6% and below 2.5% (relative standard deviation, RSD), respectively. The carry-over following injection of 0.5 ng per protein was less than 1.1%. The retention time dependence on column temperature was investigated in the range 20–50 °C. Proteins in a skimmed milk sample were separated using the method. 相似文献
9.
Holm A Storbråten E Mihailova A Karaszewski B Lundanes E Greibrokk T 《Analytical and bioanalytical chemistry》2005,382(3):751-759
A comprehensive two-dimensional capillary liquid chromatographic (2D LC) method has been established for determination of neuropeptides in rat brain tissue. Rats were exposed to different levels of stress before sacrificing and the aim of this study was to design a powerful separation and detection technique capable of characterizing differences between cerebral neuropeptide expression as a function of stress level. Rat brain samples were homogenized and subjected to clean-up by solid-phase extraction (SPE) on both a reversed-phase (C18) and a weak cation-exchange (CBA) cartridge. The samples were divided in two fractions (A and B) depending on retention on the CBA column. Subsequently, 50 L of the sample were injected on to a strong cation exchanger (SCX) at a mobile phase pH of 3, which enabled preconcentration of positively charged compounds. The trapped compounds were eluted using step gradients of ammonium formate in water–ACN (90:10, v/v). Before enrichment in the second dimension, the eluate from the first dimension was diluted with water containing 0.1% TFA. The compounds eluting from the first dimension were trapped in the second dimension using a dual precolumn system consisting of two short capillary columns packed with Kromasil C18, 10 m particles. Subsequently, the trapped compounds were backflushed on to a 10 cm long, 320 m I.D. analytical column packed with Kromasil C18 3.5 m particles, on which they were efficiently separated. Detection was performed using an ion-trap mass spectrometer (ITMS) in both the MS and the MS–MS mode. Comparison of base-peak chromatograms (BPC) from MS analysis of stressed and non-stressed rats clearly revealed several differences in neuropeptide expression. The MS–MS data obtained combined with Mascot software were employed for peptide identification. 相似文献
10.
A blue light-inducible phosphodiesterase (PDE) activity, specific for the hydrolysis of cyclic di-GMP (c-di-GMP), has been identified in a recombinant protein from Synechococcus elongatus. Blue light (BL) activation is accomplished by a light, oxygen, voltage (LOV) domain, found in plant phototropins and bacterial BL photoreceptors. The genome of S. elongatus contains two genes coding for proteins with LOV domains fused to EAL domains (SL1 and SL2). In both cases, a GGDEF motif is placed in between the LOV and the EAL motifs. Such arrangement is frequently found with diguanylate-cyclase (DGC) functions that form c-di-GMP. Cyclic di-GMP acts as a second messenger molecule regulating biofilm formation in many microbial species. Both enzyme activities modulate the intracellular level of this second messenger, although in most proteins only one of the two enzyme functions is active. Both S. elongatus LOV-GGDEF-EAL proteins were expressed in full length or as truncated proteins. Only the SL2 protein, expressed as a LOV-GGDEF-EAL construct, showed an increase of PDE activity upon BL irradiation, demonstrating this activity for the first time in a LOV-domain protein. Addition of GTP or c-di-GMP did not affect the observed enzymatic activity. In none of the full-length or truncated proteins was a DGC activity detected. 相似文献