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991.
Michele M. Farris Alec A. Klinghoffer Joseph A. RosSnl David E. Tevault 《Catalysis Today》1992,11(4):501-516
A 5% Pt/Al2O3 catalyst was exposed to hexafluoropropylene (HFP) at concentrations between 500 and 4,500 ppm in humid air at temperatures between 300 and 400°C. The catalyst was found to deactivate over all conditions investigated. Analysis of the catalyst following reaction exposure indicated that the catalyst support had been transformed to aluminum fluoride, and that virtually all of the support's surface area had been lost. The observed deactivation was attributed to degradation of the catalyst support, caused by a reaction between the alumina support and product hydrofluoric acid. Under some conditions, the rate of catalytic deactivation was found to be proportional to the number of moles of hexafluoropropylene reacted. 相似文献
992.
M Kramer E Schimke M Gerwing S Schleich U Michele 《Canadian Metallurgical Quarterly》1998,26(4):238-246
Dogs and cats rarely have problems with the Achilles tendon and if so, it usually results from a direct trauma. Prime area for injuries is the insertion on the tuber calcanei or directly proximal. One defers between complete and partial ruptures, acute and chronic injuries as well as displacement of the tendon of the superficial digital flexor muscle. In 38 cases (33 dogs and five cats) the clinical examination, radiology, ultrasonography and therapy are shown. Usually the clinical examination is sufficient for a diagnosis (hyperflexion of the hock and weight-bearing on the plantar surface of the metatarsus). The radiology primarily shows up abnormalities on the calcaneus, mineralisations of the tendon and allows the assessment of implants. Ultrasonography is the diagnostic imaging of choice for judgement of tendon diseases as well as the progress of their healing. Tendon suture is advisable if the rupture is open, fresh and/or complete and in cases of luxation of the superficial digital flexor muscle. Immobilisation of the tarsus in hyperextension seems to be of utmost importance no matter if an operative or conservative therapy is chosen. 相似文献
993.
994.
Mattia P. Arena Graziano Caggianiello Daniela Fiocco Pasquale Russo Michele Torelli Giuseppe Spano Vittorio Capozzi 《International journal of molecular sciences》2014,15(2):3025-3039
Currently, the majority of prebiotics in the market are derived from non-digestible oligosaccharides. Very few studies have focused on non-digestible long chain complex polysaccharides in relation to their potential as novel prebiotics. Cereals β-glucans have been investigated for immune-modulating properties and beneficial effects on obesity, cardiovascular diseases, diabetes, and cholesterol levels. Moreover, β-glucans have been reported to be highly fermentable by the intestinal microbiota in the caecum and colon, and can enhance both growth rate and lactic acid production of microbes isolated from the human intestine. In this work, we report the effects of food matrices containing barley β-glucans on growth and probiotic features of four Lactobacillus strains. Such matrices were able to improve the growth rate of the tested bacteria both in unstressed conditions and, importantly, after exposure to in vitro simulation of the digestive tract. Moreover, the effect of β-glucans-containing food on bacterial adhesion to enterocyte-like cells was analyzed and a positive influence on probiotic-enterocyte interaction was observed. 相似文献
995.
996.
A time‐series model in which the signal is buried in noise that is non‐Gaussian may throw up observations that, when judged by the Gaussian yardstick, are outliers. We describe an observation‐driven model, based on an exponential generalized beta distribution of the second kind (EGB2), in which the signal is a linear function of past values of the score of the conditional distribution. This specification produces a model that is not only easy to implement but which also facilitates the development of a comprehensive and relatively straightforward theory for the asymptotic distribution of the maximum‐likelihood (ML) estimator. Score‐driven models of this kind can also be based on conditional t distributions, but whereas these models carry out what, in the robustness literature, is called a soft form of trimming, the EGB2 distribution leads to a soft form of Winsorizing. An exponential general autoregressive conditional heteroscedastic (EGARCH) model based on the EGB2 distribution is also developed. This model complements the score‐driven EGARCH model with a conditional t distribution. Finally, dynamic location and scale models are combined and applied to data on the UK rate of inflation. 相似文献
997.
998.
Films made from poly(vinyl alcohol‐co‐ethylene) and soluble biopolymers isolated from postharvest tomato plant 下载免费PDF全文
Flavia Franzoso Diego Antonioli Enzo Montoneri Paola Persico Silvia Tabasso Michele Laus Raniero Mendichi Michele Negre Carlos Vaca‐Garcia 《应用聚合物科学杂志》2015,132(18)
Blended films were obtained from polyvinyl alcohol‐co‐ethylene (EVOH) with 52 kDa weight average molecular weight (Mw) and three water soluble biopolymers isolated from exhausted tomato plants hydrolysates. Two biopolymers contained mainly polysaccharides and had 27 and 79 kDa Mw, respectively. The third contained mainly lignin‐like C moieties and had 392 kDa MW. The films were fabricated with a biopolymer/EVOH w/w ratio ranging from 0.1 to 0.9. All blends had molecular weight and solubility which were substantially different from the starting materials. They were characterized for the chemical nature, and the thermal, rheological, and mechanical properties. Evidence of a chemical reaction between the biopolymers and EVOH was found. Generally, the films exhibited higher mechanical strength but lower strain at break then the neat EVOH. The best performing blended film was fabricated from the 27 kDa Mw polysaccharide. This contained less than 10% biopolymer. It exhibited 1043 MPa Young's modulus and 70% strain at break against 351 MPa modulus and 86% strain for neat EVOH. The results offer scope for investigating biopolymers sourced from other biowastes to understand more the reasons of the observed effects and exploit their full potential to modify or to replace synthetic polymers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41935. 相似文献
999.
Improving PCA‐based anomaly detection by using multiple time scale analysis and Kullback–Leibler divergence 下载免费PDF全文
Christian Callegari Loris Gazzarrini Stefano Giordano Michele Pagano Teresa Pepe 《International Journal of Communication Systems》2014,27(10):1731-1751
The increasing number of network attacks causes growing problems for network operators and users. Thus, detecting anomalous traffic is of primary interest in IP networks management. In this paper, we address the problem considering a method based on PCA for detecting network anomalies. In more detail, this paper presents a new technique that extends the state of the art in PCA‐based anomaly detection. Indeed, by means of multi‐scale analysis and Kullback–Leibler divergence, we are able to obtain great improvements with respect to the performance of the ‘classical’ approach. Moreover, we also introduce a method for identifying the flows responsible for an anomaly detected at the aggregated level. The performance analysis, presented in this paper, demonstrates the effectiveness of the proposed method.Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
1000.
Gianlorenzo Bussetti Marcello Campione Michele Riva Andrea Picone Luisa Raimondo Lorenzo Ferraro Conor Hogan Maurizia Palummo Alberto Brambilla Marco Finazzi Lamberto Duò Adele Sassella Franco Ciccacci 《Advanced functional materials》2014,24(7):958-963
A major challenge in molecular electronics is to develop logic devices based on a truly intramolecular switching mechanism. Recently, a new type of molecular device has been proposed where the switching characteristic is mediated by the bistability in the position of the two hydrogen atoms which can occupy different, energetically equivalent positions (tautomerization) in the inner cavity of porphyrins and naphthalocyanines. Up to now, such a reaction has only been exploited at low temperatures and induced or detected through atomic scale manipulation. In addition, the unpredictability of the tautomer orientation currently excludes molecular interconnection to functional electronic circuits. Here, full evidence is provided that, following a newly proposed growth strategy, 2D layers of metal‐free tetraphenylporphyrins (H2TPP) show frozen tautomerization even at room temperature on macroscopic domains, with the H atoms aligned along a direction settled a priori. This behavior is ascribed to the buckling of the molecule, anchored to the substrate, which removes the degeneracy between the two tautomer alignments. On this basis, a new way to exploit uniaxially oriented H2TPP tautomers in a first elementary logic device is proposed. 相似文献