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21.
Gergana I. Drandova Troy C. Messina Jae-Hyuk Choi Javier F. Hernandez John T. Markert 《Journal of Low Temperature Physics》2003,131(3-4):305-309
We report NMR lineshape, spin-lattice relaxation time T
1, and spin-spin relaxation time T
2 data at 17 MHz (8.07 T) for 89Y in the copper-oxide spin-chain compound Ca2+x
Y2–x
Cu5O10. For x=0, a broad, asymmetric line with width 90 kHz is observed for T=250–300 K. The spectra exhibit an appreciable average shift (H/H+0.7%) and sharpen at lower temperature, possibly due to increasing intrachain ferromagnetic correlations. T
1 and T
2 decrease with decreasing temperature. The Tl data imply a short correlation-time limit, with e=3–5×10–11 s. The T
2 data apparently include a contribution from dipolar interactions with copper nuclei. Relaxation time data for a doped (x=0.5) compound surprisingly show more rapid relaxation. 相似文献
22.
In this paper, a new analysis technique for predicting and characterizing nonlinear behavior of stressed power networks is proposed. Making use of an analytical approximation of the system nonlinear model via the use of a truncated Carleman linearization technique, a bilinear state-space model of the power system is developed in which the second and higher order nonlinear terms are explicitly incorporated in the series expansion representation of the system model. 相似文献
23.
Shengpan Lin Nathan J. Moore Joseph P. Messina 《International journal of remote sensing》2013,34(13):4669-4679
Satellite remote-sensing technology has shown promising results in characterizing the environment in which plants and animals thrive. Scientists, biologists, and epidemiologists are adopting remotely sensed imagery to compensate for the paucity of weather information measured by weather stations. With measured humidity from three stations as baselines, our study reveals that normalized difference vegetation index (NDVI) and atmospheric saturation deficit at the 780 hPa pressure level (DMODIS), both of which were derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor, were significantly correlated with station saturation deficits (Dstn) (|r| = 0.42–0.63, p < 0.001). These metrics have the potential to estimate saturation deficits over east Africa. Four to nine days of lags were found in the NDVI responding to Dstn. For the daily estimation of Dstn, DMODIS yielded better performance than the NDVI. However, both of them poorly explained variation in daily Dstn using simple regression models (adj. R2 = 0.17–0.39). When the estimation temporal scale was changed to 16 days, performance was similar, and both were better than daily estimations. For Dstn estimation at coarser geographic scales, given that many factors such as soil, vegetation, slope, aspect, and wind speed might complicate NDVI response lags and model construction, DMODIS is preferable as a proxy to saturation deficit over ground due to its simple relationship with Dstn. 相似文献
24.
25.
Danilo Ercolini Ilario Ferrocino Antonietta La Storia Gianluigi Mauriello Sergio Gigli Paolo Masi Francesco Villani 《Food microbiology》2010
The aim of this study was to assess the microbial populations causing the spoilage of chilled beef during storage and to evaluate the effect of the use of an antimicrobial packaging for the meat storage. A nisin activated antimicrobial packaging was developed by using a nisin, HCL and EDTA solution and used for the storage of beef cuts at 1 °C. The common spoilage related microbial groups were monitored during the storage of beef in activated and non activated plastic bags by using selective media. The use of the antimicrobial packaging caused an overall significant reduction of viable counts of Gram positive bacteria such as carnobacteria, lactic acid bacteria and Brochotrix thermosphacta whose development was inhibited for at least 11 days of storage compared to the control. Moreover, a 1–3 log cycles reduction of enterobacteria was also registered between 22 and 32 days of storage. The microbiota was assessed at species level by using Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis of 16S rRNA gene of DNA extracted directly from meat and from bulk cells from selective media plates and showed that the species occurring within the targeted microbial groups did not change according to storage conditions. In conclusion, the use of the nisin activated packaging reduced the number of spoilage populations but did not affect the species diversity. Improved antimicrobial packaging is needed, possibly coupled with vacuum storage, to possibly achieve a simultaneous inhibition of more spoilage microbial groups and to preserve the microbiological quality of beef during chilled storage. 相似文献
26.
Potent,Metabolically Stable 2‐Alkyl‐8‐(2H‐1,2,3‐triazol‐2‐yl)‐9H‐adenines as Adenosine A2A Receptor Ligands 下载免费PDF全文
Dr. Silvia Pace Dr. Giandomenico Brogin Dr. Maria Antonietta Stasi Dr. Teresa Riccioni Franco Borsini Dr. Francesca Capocasa Dr. Francesco Manera Carlo Tallarico Dr. Pietro Grossi Dr. Federica Vacondio Dr. Michele Bassi Dr. Francesca Bartoccini Dr. Simone Lucarini Dr. Giovanni Piersanti Prof. Giorgio Tarzia Walter Cabri Dr. Patrizia Minetti 《ChemMedChem》2015,10(7):1149-1152
Inhibition of adenosine A2A receptors has been shown to elicit a therapeutic response in preclinical animal models of Parkinson’s disease (PD). We previously identified the triazolo‐9H‐purine, ST1535, as a potent A2AR antagonist. Studies revealed that ST1535 is extensively hydroxylated at the ω‐1 position of the butyl side chain. Here, we describe the synthesis and evaluation of derivatives in which the ω‐1 position has been substituted (F, Me, OH) in order to block metabolism. The stability of the compounds was evaluated in human liver microsomes (HLM), and the affinity for A2AR was determined. Two compounds, (2‐(3,3‐dimethylbutyl)‐9‐methyl‐8‐(2H‐1,2,3‐triazol‐2‐yl)‐9H‐purin‐6‐amine ( 3 b ) and 4‐(6‐amino‐9‐methyl‐8‐(2H‐1,2,3‐triazol‐2‐yl)‐9H‐purin‐2‐yl)‐2‐methylbutan‐2‐ol ( 3 c ), exhibited good affinity against A2AR (Ki=0.4 nM and 2 nM , respectively) and high in vitro metabolic stability (89.5 % and 95.3 % recovery, respectively, after incubation with HLM for two hours). 相似文献
27.
Carlo Alberto Biffi Paola Bassani Marco Carnevale Nora Lecis Antonietta Loconte Barbara Previtali Ausonio Tuissi 《Metals and Materials International》2014,20(1):83-92
The machining of shape memory alloys (SMAs), such as NiTi based alloys, is a very interesting and relevant topic for several industrial applications in the biomedical, sensor and actuator fields. Laser technology is one of the most suitable methods for the manufacturing of products in the aforementioned fields, mainly when small and precise features have to be included. Due to the thermal nature of this process, study of its effect on the functional properties of these materials is needed. Except for binary NiTi, few results on the laser machining of NiTi based alloys are available in the literature. In this work, thin sheets of Ni40Ti50Cu10 (at.%) were processed by a fibre laser and the effect of process speed on the material properties was analysed. Scanning electronic microscopy was adopted for observation of the laser cut edges’ morphology. Chemical composition of the processed material was evaluated by energy dispersion spectroscopy and nanohardness measurements were used to estimate the heat affected zone. SMA functional properties were studied on both base and laser machined material. These characteristics are affected by laser machining for the presence of melted material; this effect can be minimised by increasing the laser process speed. 相似文献
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29.
S. Santangelo M. Dhanagopal G. Faggio G. Messina A. Pistone M. Lanza C. Milone 《Diamond and Related Materials》2010,19(5-6):599-603
Nanotubes-clay hybrid systems are synthesized by decomposition of isobutane at 700 °C over as-purchased and iron-loaded montmorillonite catalysts. The changes produced by the variations of total iron content (2–17 wt.%) and of reduction-temperature (500 °C or 700 °C) in catalyst surface properties, as well as, in reaction yield and crystalline quality of C deposits are discussed. A growth mechanism is proposed accounting for the bi-functional behavior of catalyst and the role, played by the clay support acidity with regard to the process selectivity and the resulting crystallinity degree of reaction products, is demonstrated. The decrease of number of catalyst acid sites, by reduction at 700 °C or by sodium exchange reaction, inhibits the formation of highly disordered carbonaceous nanostructures, responsible for metal deactivation and scarce selectivity at small iron loads. It is worth noting that catalysts prepared with sodium-exchanged clay allow obtaining crystallinity degrees higher than those ever reported in literature for similarly grown nanotubes. 相似文献
30.