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161.
Alessandro Faccinetto Dr. Simone Mazzucato Dr. Danilo Pedron Prof. Renato Bozio Prof. Silvia Destri Dr. William Porzio Dr. 《Chemphyschem》2008,9(14):2028-2034
The nonlinear optical properties of a functionalized poly(thiophene azine), namely, poly(3,4‐didodecylthiophene azine), PAZ, at the optical telecommunication wavelength of 1550 nm are investigated by means of the closed‐aperture z‐scan technique in both thin films and solutions. Values of χ(3)=(2.4±0.4)×10?13 esu, n2=(4.0±0.7)×10?15 cm2 W?1, and γ=(4.5±0.7)×10?34 esu are estimated for the third‐order (Kerr) susceptibility, the intensity‐dependent refractive index, and the molecular second hyperpolarizability of solution samples, respectively. A very small dependence on the polymer chain length is found. Markedly higher values of (4.4±1.1)×10?11 esu, (6.6±1.0)×10?13 cm2 W?1, and (5.0±0.8)×10?33 esu are measured for the corresponding quantities in thick (up to 20 μm) polymer films cast on quartz plates. The enhancement of the NLO responses on going from solution to solid samples is attributed to a partially ordered structure and to the presence of interchain interactions leading to greater π‐electron delocalization in the cast polymer films. The results are compared with those previously obtained by using third‐harmonic generation (THG), taking into account that those data were measured under conditions of three‐photon resonance, whereas our z‐scan measurements are fully off‐resonance. 相似文献
162.
Stolker AA Rutgers P Oosterink E Lasaroms JJ Peters RJ van Rhijn JA Nielen MW 《Analytical and bioanalytical chemistry》2008,391(6):2309-2322
Ultra-performance liquid chromatography combined with time-of-flight mass spectrometry (UPLC–ToF-MS) has been used for screening
and quantification of more than 100 veterinary drugs in milk. The veterinary drugs represent different classes including benzimidazoles,
macrolides, penicillins, quinolones, sulphonamides, pyrimidines, tetracylines, nitroimidazoles, tranquillizers, ionophores,
amphenicols and non-steroidal anti-inflammatory agents (NSAIDs). After protein precipitation, centrifugation and solid-phase
extraction (SPE), the extracts were analysed by UPLC–ToF-MS. From the acquired full scan data the drug-specific ions were
extracted for construction of the chromatograms and evaluation of the results. The analytical method was validated according
to the EU guidelines (2002/657/EC) for a quantitative screening method. At the concentration level of interest (MRL level)
the results for repeatability (%RSD < 20% for 86% of the compounds), reproducibility (%RSD < 40% for 96% of the compounds)
and the accuracy (80–120% for 88% of the compounds) were satisfactory. Evaluation of the CCβ values and the linearity results demonstrates that the developed method shows adequate sensitivity and linearity to provide
quantitative results. Furthermore, the method is accurate enough to differentiate between suspected and negative samples or
drug concentrations below or above the MRL. A set of 100 samples of raw milk were screened for residues. No suspected (positive)
results were obtained except for the included blind reference sample containing sulphamethazine (88 μg/l) that tested positive
for this compound. UPLC–ToF-MS combines high resolution for both LC and MS with high mass accuracy which is very powerful
for the multi-compound analysis of veterinary drugs. The technique seems to be powerful enough for the analysis of not only
veterinary drugs but also organic contaminants like pesticides, mycotoxins and plant toxins in one single method. 相似文献
163.
Carey?E.?PriebeEmail author John?M.?Conroy David?J.?Marchette Youngser?Park 《Computational & Mathematical Organization Theory》2005,11(3):229-247
We introduce a theory of scan statistics on graphs and apply the ideas to the problem of anomaly detection in a time series
of Enron email graphs.
Previous presentation: Workshop on Link Analysis, Counterterrorism and Security at the SIAM International Conference on Data
Mining, Newport Beach, CA, April 23, 2005.
Carey E. Priebe received the B.S. degree in mathematics from Purdue University in 1984, the M.S. degree in computer science from San Diego
State University in 1988, and the Ph.D. degree in information technology (computational statistics) from George Mason University
in 1993. From 1985 to 1994 he worked as a mathematician and scientist in the US Navy research and development laboratory system.
Since 1994 he has been a professor in the Department of Applied Mathematics and Statistics, Whiting School of Engineering,
Johns Hopkins University, Baltimore, Maryland. At Johns Hopkins, he holds joint appointments in the Department of Computer
Science and the Center for Imaging Science. He is a past President of the Interface Foundation of North America—Computing
Science & Statistics, a past Chair of the Section on Statistical Computing of the American Statistical Association, and on
the editorial boards of Journal of Computational and Graphical Statistics, Computational Statistics and Data Analysis, and
Computational Statistics. His research interests are in computational statistics, kernel and mixture estimates, statistical
pattern recognition, statistical image analysis, and statistical inference for high-dimensional and graph data. He was elected
Fellow of the American Statistical Association in 2002.
John M. Conroy received a B.S. in Mathematics from Saint Joseph's University in 1980 and a Ph.D. in Applied Mathematics from the University
of Maryland in 1986. Since then he has been a research staff member for the IDA Center for Computing Sciences in Bowie, MD.
His research interest is applications of numerical linear algebra. He is a member of the Society for Industrial and Applied
Mathematics, Institute of Electrical and Electronics Engineers (IEEE), and the Association for Computational Linguistics.
David J. Marchette received a B.A. in 1980, and an M.A. in mathematics in 1982, from the University of California at San Diego. He received
a Ph.D. in Computational Sciences and Informatics in 1996 from George Mason University under the direction of Ed Wegman. From
1985–1994 he worked at the Naval Ocean Systems Center in San Diego doing research on pattern recognition and computational
statistics. In 1994 he moved to the Naval Surface Warfare Center in Dahlgren Virginia where he does research in computational
statistics and pattern recognition, primarily applied to image processing, text processing, automatic target recognition and
computer security. Dr. Marchette is a Fellow of the American Statistical Society.
Youngser Park received the B.E. degree in electrical engineering from Inha University in Korea in 1985, the M.S. degree in computer science
from The George Washington University in 1991, and had pursued a doctoral degree there. From 1998 to 2000 he worked at the
Johns Hopkins Medical Institutes as a senior research engineer. Since 2003 he is working as a research analyst in the Center
for Imaging Science at the Johns Hopkins University. His research interests are clustering algorithm, pattern classification,
and data mining. 相似文献
164.
《Journal of separation science》2018,41(18):3515-3526
Benzoyl aconite alkaloids have myocardial protective effects at a low dose and produce toxic effects at high dose. Due to lack of enough reference compounds, most of the benzoyl alkaloids had few concerns, except the typical ones, i.e. aconitine, mesaconitine, and hypaconitine. To rapidly screen out and quantify benzoyl alkaloids, a high performance liquid chromatography combined with tandem mass spectrometry was proposed based on precursor ion scanning mode. First, a diagnostic ion at m/z 105 corresponding to benzoyl group was observed by using tandem mass spectrometry, which could be used for the rapid identification of benzoyl alkaloids. The targeted screening of these alkaloids was then conducted by using precursor ion scan of characteristic ion at m/z 105. Shengfuzi (the lateral root of A. carmichaelii) was taken as example, and 24 benzoyl‐containing alkaloids were identified. The six major alkaloids including aconitine, mesaconitine, hypaconitine, benzoylaconine, benzoylmesaconine, and benzoylhypaconine were determined in the precursor ion scan mode by the standard curve method. Reliable linearity, sensitivity, precision, accuracy, and repeatability were obtained and validated. Then the relative response factors between these six analytes were calculated, which were not more than two times using any alkaloid as reference. Thus, the other 18 alkaloids lacking reference compounds were relatively quantified. This approach provides a useful tool for rapid identification and quantitative analysis of toxic benzoyl alkaloids, and also an efficient method for the safety assessment of Aconitum roots. 相似文献
165.
Ulrich Reineke Robert Sabat Achim Kramer Rolf D. Stigler Martina Seifert Thomas Michel Hans D. Volk Jens Schneider-Mergener 《Molecular diversity》1996,1(3):141-148
Summary We have characterized the interaction of two monoclonal antibodies with their respective antigens using cellulose-bound sets of overlapping peptides (peptide scans). Both antibodies CB/RS/5 and CB/MT/1 recognize discontinuous epitopes present in human interleukin-10 (IL-10) and tumor necrosis factor alpha (TNF-). In addition, the interaction between TNF-a and its 55-kDa receptor (TNF-R) was investigated by the same approach. Both antibodies, as well as TNF-, interacted with two or more regions of the peptide scans. Antibody-binding competition studies between the native antigens and peptides, covering single parts of the binding regions, enabled us to distinguish between binding to the paratope or other regions of the antibody. The combination of these experimental approaches allowed the identification of short antigen-derived sequences that are separated on the primary sequence but close in space on the surface of IL-10 and TNF-, thus representing putative discontinuous epitopes. In the case of the TNF-R-derived peptide scans, two of the identified regions interact with the structurally similar TNF- in the TNF--TNF-R complex. These data indicate that this approach should be generally applicable for mapping nonlinear protein-protein contact sites. 相似文献
166.
《Electroanalysis》2006,18(2):201-206
A composite electrode prepared from graphite powder and epoxy resin was applied as a working electrode for the determination of phenylglyoxylic acid (one of the metabolites of styrene) in human urine. Cathodic differential pulse stripping voltammetry was used and optimum conditions have been found giving the limit of determination about 5 mg L?1. All results were compared with those obtained using hanging mercury drop electrode. For the confirmation of suggested mechanism of the electrochemical reaction the elimination voltammetry with linear scan was used. 相似文献
167.
The key technique in super-resolution reconstruction is sub-pixel scan, which is mainly achieved by moving detector or optic axis. Moving optic axis is performed by rotating or vibrating one optical component of the imaging lens. However, the machining requirements of the optical component for sub-pixel scan are rigorous or sometimes even impossible. A sur-pixel scan method is proposed, it can effectively restrain frequency aliasing while having lower machining requirements compared to sub-pixel scan. In this paper, the effect of sur-pixel scan on image frequency aliasing is theoretically analysed, its engineering superiority is mathematically calculated in visible spectrum and infrared spectrum. Simulations and experiments are performed to validate the effectiveness of sur-pixel scan method. 相似文献
168.
Abhay Taksande 《光谱学快报》2013,46(4):345-356
Commercial automotive fuels available on the Indian subcontinent like petrol and diesel are heavily adulterated with kerosene. Kerosene is used as a cooking fuel among the vast rural and urban populations in India. It is heavily subsidized in the local markets; hence, it becomes a cheap and commonly available adulterant. Intelligent mixing of this product with automotive fuels escapes detection. In this work, we report the synchronous fluorescence scan (SFS) technique as a direct tool to both identify and quantify the amount of adulterant present in commercial petrol and diesel mixtures across the city of Pune. The assay reported here promises to be an efficient tool for such detection purposes (kerosene as low as 1% v/v) within a limited geographical area using conditions of calibration with local components. 相似文献
169.
Giuseppe Zaccai 《Journal of Non》2011,357(2):615-621
After a double decade of intensive neutron scattering studies of the biological physics of protein dynamics on a few well-characterised model systems, the time has come to extend the method to address the vast biological diversity of proteins and their dynamics-function relationships. The time-scale and length-scale dependent mean square displacement and effective force constant, measured by neutron elastic intensity temperature scans, are proposed as relevant experimental parameters, and examples are given of their correlation with biological function. The parameters are directly calculable from molecular dynamics simulations, and their proposed deposit in an accessible data bank will greatly strengthen the links between experimental and theoretical approaches to protein dynamics. 相似文献
170.
《Analytical letters》2012,45(11):2293-2304
ABSTRACT Micellization is described as a successful media for simultaneous fluorimetric determination of perylene, pyrene and triphenylene in water samples by reducing interference between them. A multivariate method based on synchronous fluorescence scan to estimate perylene, pyrene and triphenylene in their mixture solution has been proposed. The method does not require solving of large amounts of data obtained from the whole spectrum of the samples, thus making the analysis simple and fast. The method gives the best result for perylene and satisfactory results for pyrene and triphenylene. Analysis of water samples of two different origins spiked with known amount of perylene, pyrene and triphenylene also gives satisfactory result. Presence of fluoranthene up to 1 μM does not interfere in the analysis. 相似文献