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341.
Parisi D Magliulo M Nanni P Casale M Forina M Roda A 《Analytical and bioanalytical chemistry》2008,391(6):2127-2134
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a useful technique for the
identification of bacteria on the basis of their characteristic protein mass spectrum fingerprint. Highly standardized instrumental
analytical performance and bacterial culture conditions are required to achieve useful information. A chemometric approach
based on multivariate analysis techniques was developed for the analysis of MALDI data of different bacteria to allow their
identification from their fingerprint. Principal component analysis, linear discriminant analysis (LDA) and soft independent
modelling of class analogy (SIMCA) were applied to the analysis of the MALDI MS mass spectra of two pathogenic bacteria, Escherichia coli O157:H7 and Yersinia enterocolitica, and the non-pathogenic E. coli MC1061. Spectra variability was assessed by growing bacteria in different media and analysing them at different culture growth
times. After selection of the relevant variables, which allows the evaluation of an m/z value pattern with high discriminant power, the identification of bacteria by LDA and SIMCA was performed independently of
the experimental conditions used. In order to better evaluate the analytical performance of the approach used, the ability
to correctly classify different bacteria, six wild-type strains of E. coli O157:H7, was also studied and a combination of different chemometric techniques with a severe validation was developed. The
analysis of spiked bovine meat samples and the agreement with an independent chemiluminescent enzyme immunoassay demonstrated
the applicability of the method developed for the detection of bacteria in real samples. The easy automation of the MALDI
method and the ability of multivariate techniques to reduce interlaboratory variability associated with bacterial growth time
and conditions suggest the usefulness of the proposed MALDI MS approach for rapid routine food safety checks.
Figure Workflow of the developed MALDI-TOF MS and chemometric approach for the analysis and classification of bacteria
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
342.
Nathan Downs Nawin Raj Jennifer Vanos Alfio V. Parisi Harry Butler Ravinesh Deo Damien Igoe Benjamin Dexter Melanie Beckman-Downs Joanna Turner Stijn Dekeyser 《Photochemistry and photobiology》2023,99(4):1193-1207
Current shading strategies used to protect outdoor playgrounds from harmful solar radiation include the placement of artificial cloth weaves or permanent roofing over a playground site, planting trees in proximity to playground equipment, and using vegetation or surface texture variations to cool playground surfaces. How and where an artificial shade structure is placed or a tree is planted to maximize the shade protection over specific playground areas, requires careful assessment of local seasonal sun exposure patterns. The Playground Shade Index (PSI) is introduced here as a design metric to enable shade and solar ultraviolet exposure patterns to be derived in an outdoor space using conventional aerial views of suburban park maps. The implementation of the PSI is demonstrated by incorporating a machine learning design tool to classify the position of trees from an aerial image, thus enabling the mapping of seasonal shade and ultraviolet exposure patterns within an existing 7180 m2 parkland. This is achieved by modeling the relative position of the sun with respect to nearby buildings, shade structures, and the identified evergreen and deciduous tree species surrounding an outdoor playground. 相似文献
343.
Giuseppina Anna Corrente Francesco Parisi Vito Maltese Sante Cospito Daniela Imbardelli Massimo La Deda Amerigo Beneduci 《Molecules (Basel, Switzerland)》2021,26(22)
Electrofluorochromic devices (EFCDs) that allow the modulation of the light emitted by electroactive fluorophores are very attractive in the research field of optoelectronics. Here, the electrofluorochromic behaviour of a series of squaraine dyes was studied for the first time. In solutions, all compounds are photoluminescent with maxima located in the range 665–690 nm, characterized by quantum yields ranging from 30% to 4.1%. Squaraines were incorporated in a polymer gel used as an active layer in all-in-one gel switchable EFCDs. An aggregation induced quenching occurs in the gel phase, causing a significant decrease in the emission quantum yield in the device. However, the squaraines containing the thieno groups (thienosquaraines, TSQs) show a panchromatic emission and their electrofluorochromism allows the tuning of the fluorescence intensity from 500 nm to the near infrared. Indeed, the application of a potential difference to the device induces a reversible quenching of their emission that is significantly higher and occurs at shorter switching times for TSQs-based devices compared to the reference squaraine dye (DIBSQ). Interestingly, the TSQs fluorescence spectral profile becomes more structured under voltage, and this could be explained by the shift of the aggregates/monomer equilibrium toward the monomeric species, due to electrochemical oxidation, which causes the disassembling of aggregates. This effect may be used to modulate the colour of the fluorescence light emitted by a device and paves the way for conceiving new electrofluorochromic materials based on this mechanism. 相似文献
344.
A spectroscopic investigation on the effect of Ce3+ co-doping in fluoride KY3F10:Pr3+ crystals is presented. In particular spectroscopic measurements of three different samples of KY3F10 crystal doped with 0.3at% Pr3+ and co-doped with 0at%, 0.17at% and 0.3at% Ce3+ are discussed. Details on the growth of the crystals are also reported. Measurements were performed in the temperature range 10-300 K. Fluorescence and lifetime measurements have shown a cross relaxation between 3P0-1D2 levels of Pr3+ and 2F7/2-2F5/2 of Ce3+. Data exhibit that this effect is strictly related to the Cerium concentration. 相似文献
345.
Summary The cosmic-ray equatorial anisotropy inside broad high-speed solar-wind streams ejected by coronal holes,i.e. in quasi-stationary condition, is analysed over the years 1973–1974. From the beginning to the end of the stream the amplitudes
of the first and second harmonics of the anisotropy are found to decrease remarkably by factors 2.5 and 2.0, respectively,
while the phases do not show systematic variations. The development of the stream structure in the interplanetary space together
with the Parker theory on the diurnal anisotropy in stationary condition give a plausible explaination for the large variation
observed in the first harmonic of the anisotropy. The behaviour of the second harmonic is tentatively interpreted in the light
of current theories.
To speed up publication, the authors of this paper have agreed to not receive the proofs for correction. 相似文献