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111.
Zefi D. Anastasiadou Panagiotis D. Jannakoudakis Stella T. Girousi 《Central European Journal of Chemistry》2010,8(5):999-1008
Square wave anodic stripping voltammetry was used in simultaneous determinations of eco-toxic metals (Pb, Cd, Cu and Zn) on bismuth film electrodes. The electrodes were prepared in situ on a glassy-carbon electrode (GCE) from 0.1 M acetate buffer (pH 4.5) containing 200 μg L?1 of bismuth (III), as well ex situ on electrochemically oxidized graphitized polyacrylonitrile carbon fibres from 200 mg L?1 Bi(NO3)3 in 1% HNO3 (aqueous) solution. Preparation of a Bi-modified carbon fibre electrode (CFE) was by cation exchange of Bi+3 ions for H+ of the acidic surface groups of the electro-oxidized carbon fibres, followed by electrochemical reduction to Bi0. For the Bi-GCE the linear range was 20–280 μg L?1 for zinc, 10–100 μg L?1 for lead, 10–80 μg L?1 for copper, and 5–50 μg L?1 for cadmium. For the Bi-CFE it was 20–160 μg L?1 for zinc, 10–100 μg L?1 for lead, 10–100 μg L?1 for copper, and 2–120 μg L?1 for cadmium. For both kinds of bismuth modified carbon electrodes, low limits of detection and satisfactory precision were achieved. The method was successfully applied to certified reference materials of biological (bovine liver) and environmental (mussel tissue) importance. 相似文献
112.
Panagiotis Stogiannos Apostolos Dollas Vassilis Digalakis 《The Journal of VLSI Signal Processing》2000,24(2-3):223-240
An architecture is presented for real-time continuous speech recognition based on a modified hidden Markov model. The algorithm is adapted to the needs of continuous speech recognition by efficient encoding of the state space, and logarithmic encoding of the weights so that products can be computed as sums. The paper presents the algorithm and its application related modifications, the mapping of the algorithm to a special purpose architecture, and the detailed design of this architecture using configurable logic. Emphasis is given on how the attributes of the algorithm are exploited in a configurable logic based design. A concrete design example is presented with a coprocessor engine having one large FPGA, 64 Mbytes of synchronous DRAM (SDRAM), a small FPGA as a SDRAM controller, and 2 Mbytes SRAM. This engine operating at 66 MHz performs roughly nine times as fast as a high end personal computer running a fully optimized version of the same algorithm. 相似文献
113.
114.
We report the availability of grcarma, a program encoding for a fully automated set of tasks aiming to simplify the analysis of molecular dynamics trajectories of biological macromolecules. It is a cross‐platform, Perl/Tk‐based front‐end to the program carma and is designed to facilitate the needs of the novice as well as those of the expert user, while at the same time maintaining a user‐friendly and intuitive design. Particular emphasis was given to the automation of several tedious tasks, such as extraction of clusters of structures based on dihedral and Cartesian principal component analysis, secondary structure analysis, calculation and display of root‐mean‐square deviation (RMSD) matrices, calculation of entropy, calculation and analysis of variance–covariance matrices, calculation of the fraction of native contacts, etc. The program is free‐open source software available immediately for download. © 2013 Wiley Periodicals, Inc. 相似文献
115.
The wireless world migrates towards the “Beyond the 3rd Generation” (B3G) era. It is envisaged that the B3G era will be characterised by advances in the infrastructure, the applications/services supported, and the business model. These characteristics also mean that the management of the wireless B3G world will be more complex, compared to previous generations. It is believed that an efficient response to complexity is the introduction of cognitive systems. In this respect, the first objective of this paper is to discuss on the infrastructure-, application-, and business-driven motivation for the introduction of cognitive systems. A second objective is to introduce the basic engineering challenges for the successful introduction. The approach for presenting the motivations includes: (i) the basic features, and the consequent requirements for the management functionality, associated with the network infrastructure, application areas and business model envisaged for the wireless B3G world; (ii) argumentation that cognitive systems are efficient means for satisfying these requirements. The approach for presenting the basic engineering challenges includes: (i) the envisaged structure of a cognitive system; (ii) issues related to the deployment of the cognitive systems in a B3G infrastructure. 相似文献
116.
Chrisoula Papazoglou Panagiotis G. Sarigiannidis Georgios I. Papadimitriou Andreas S. Pomportsis 《International Journal of Communication Systems》2010,23(2):187-203
In an optical burst switched network, variable‐sized data bursts are switched on the fly using bandwidth previously reserved by their control packets. A key problem in OBS networks is the assignment of wavelengths to incoming bursts, that is, the scheduling of bursts. This paper proposes a new class of burst scheduling algorithms based on a triangular estimator. The proposed tool reduces the complexity of the scheduling scheme (measured in channel checks) without compromising its performance (measured by the burst drop ratio). Simulation results demonstrate both the accuracy and the efficiency of the estimator in a variety of scenarios and under self‐similar network traffic. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
117.
Ataullah Khan Panagiotis G. Smirniotis 《Journal of molecular catalysis. A, Chemical》2008,280(1-2):43-51
A series of modified ferrites were prepared by doping iron oxide with various transition/non-transition/inner-transition metal ions [M = Cr, Mn, Co, Ni, Cu, Zn and Ce] in situ during synthesis. All the modified ferrites thus obtained exhibit remarkably high surface areas, greater than that of pure iron oxide (Fe2O3) sample. The efficacy of the dopant ions in modifying the resultant specific surface area, could be directly related to variations in the rate of crystal growth. The nature and concentration of the foreign cations present in the system govern this variation. Interestingly all the modified ferrites, exhibit a narrow pore size distribution in the range of 4.9–25 nm. XRD analysis revealed the existence of hematite (Fe2O3) phase in all the as-prepared samples. The X-ray diffraction experiments performed on activated catalysts, confirmed the existence of magnetite (Fe3O4) phase with a nominal composition of Fe2.73M0.27O4. These inverse or mixed spinels with general formula A(1−δ)Bδ[AδB(2−δ)]O4, possess highly facile Fe3+ Fe2+ redox couple, the degree of facileness depends on the extent of synergistic interaction between iron and the other substitutent metal ion. The rapid electron hopping between Fe3+ Fe2+ in the Fe3O4 lattice system is essential to catalyze WGS reaction. From TPR it was observed that, incorporation of metal cations into the hematite (-Fe2O3) crystal structure alters the reducibility of the hematite particles, which in turn depends on the nature of the incorporated metal cation. A plausible explanation for the WGS activity over various modified ferrites has been attempted with the help of TPR analysis. 相似文献
118.
Markus Schwarz Philipp Skrinjar Michael J. Fink Stefan Kronister Thomas Mechtler Panagiotis I. Koukos Alexandre M. J. J. Bonvin David C. Kasper Hannes Mikula 《Chemical science》2020,11(47):12671
We report on the unexpected finding that click modification of iduronyl azides results in a conformational flip of the pyranose ring, which led to the development of a new strategy for the design of superior enzyme substrates for the diagnostic assaying of iduronate-2-sulfatase (I2S), a lysosomal enzyme related to Hunter syndrome. Synthetic substrates are essential in testing newborns for metabolic disorders to enable early initiation of therapy. Our click-flipped iduronyl triazole showed a remarkably better performance with I2S than commonly used O-iduronates. We found that both O- and triazole-linked substrates are accepted by the enzyme, irrespective of their different conformations, but only the O-linked product inhibits the activity of I2S. Thus, in the long reaction times required for clinical assays, the triazole substrate substantially outperforms the O-iduronate. Applying our click-flipped substrate to assay I2S in dried blood spots sampled from affected patients and random newborns significantly increased the confidence in discriminating between these groups, clearly indicating the potential of the click-flip strategy to control the biomolecular function of carbohydrates.Click-triggered flip of the conformation of a sulfated iduronyl azide afforded a superior enzyme substrate to screen for Hunter syndrome. 相似文献
119.
The aim of this work was to develop a fast method for extraction and analysis of anthocyanins in red cabbage. Pressurized hot water containing 5% of ethanol was used as an extremely efficient extraction solvent. HPLC/DAD with a monolithic column was used to accomplish a fast analysis—24 anthocyanin peaks within 18 min. Statistical design was used to optimize the studied extraction parameters: temperature (80–120 °C); sample amount (1–3 g); extraction time (6–11 min); concentration of formic acid in the extraction solvent (0–5 vol.%). The best extraction conditions for a majority of the anthocyanin peaks were 2.5 g of sample, 99 °C (at 50 bar), 7 min of extraction and a solvent composition of water/ethanol/formic acid (94/5/1, v/v/v). 相似文献
120.
Despoina Vrantza Panagiotis Kaloudis Leondios Leondiadis Thanasis Gimisis GeorgiosC. Vougioukalakis Michael Orfanopoulos Didier Gasparutto Jean Cadet Susana Encinas Cecilia Paris MiguelA. Miranda 《Helvetica chimica acta》2006,89(10):2371-2386
The photochemistry of N‐hydroxypyridine‐2(1H)‐thione (NHPT), inserted as a photolabile modifier at the 6‐position of 2′‐deoxyguanosine or guanosine, has been evaluated. In particular, 6‐[(1‐oxidopyridin‐2‐yl)sulfanyl]‐ ( 1a ) and 6‐[(pyridin‐2‐yl)sulfanyl]‐2′,6‐dideoxyguanosine ( 2a ), novel photolabile derivatives of the natural nucleosides, were synthesized and characterized. The observed photolysis products of 1a in organic solvents could only be rationalized by assuming a rapid equilibrium with the corresponding 6‐[(2‐thioxopyridin‐1(2H)‐yl)oxy] analogue 3a (Scheme 5). Transient spectroscopy of 1a indicated a strong triplet‐excited state suitable for triplet → triplet energy transfer or singlet‐oxygen generation. The NHPT function was stable enough for (slightly modified) automated solid‐phase oligonucleotide synthesis. The utility of the above compounds is discussed, as well as their potential use in photosensitization of reactive oxygen species in DNA. 相似文献