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91.
Valber Elias de Almeida Gean Bezerra da Costa David Douglas de Sousa Fernandes Paulo Henrique Gonçalves Dias Diniz Deysiane Brandão Ana Claudia Dantas de Medeiros Germano Véras 《Analytical and bioanalytical chemistry》2014,406(24):5989-5995
In this work, a new approach is proposed to verify the differentiating characteristics of five bacteria (Escherichia coli, Enterococcus faecalis, Streptococcus salivarius, Streptococcus oralis, and Staphylococcus aureus) by using digital images obtained with a simple webcam and variable selection by the Successive Projections Algorithm associated with Linear Discriminant Analysis (SPA-LDA). In this sense, color histograms in the red–green–blue (RGB), hue-saturation-value (HSV), and grayscale channels and their combinations were used as input data, and statistically evaluated by using different multivariate classifiers (Soft Independent Modeling by Class Analogy (SIMCA), Principal Component Analysis-Linear Discriminant Analysis (PCA-LDA), Partial Least Squares Discriminant Analysis (PLS-DA) and Successive Projections Algorithm-Linear Discriminant Analysis (SPA-LDA)). The bacteria strains were cultivated in a nutritive blood agar base layer for 24 h by following the Brazilian Pharmacopoeia, maintaining the status of cell growth and the nature of nutrient solutions under the same conditions. The best result in classification was obtained by using RGB and SPA-LDA, which reached 94 and 100 % of classification accuracy in the training and test sets, respectively. This result is extremely positive from the viewpoint of routine clinical analyses, because it avoids bacterial identification based on phenotypic identification of the causative organism using Gram staining, culture, and biochemical proofs. Therefore, the proposed method presents inherent advantages, promoting a simpler, faster, and low-cost alternative for bacterial identification. Figure
Summary of the new proposed methodology for bacteria classification by using color histograms and SPA-LDA 相似文献
92.
M Pattabiraman G Rangarajan Kwang-Yong Choi P Lemmens G Guentherodt G Balakrishnan DMcK Paul MR Lees 《Pramana》2002,58(5-6):1013-1017
We report polarized Raman scattering in single crystals of Nd0.7Sr0.3MnO3. The temperature dependence of the MnO6 octahedral bending and stretching modes observed in the XX spectra points to the existence of local lattice distortions,
possibly polarons. The XY spectra have been analyzed using a collision-dominated model, which allows the extraction of the
carrier scattering rate. 相似文献
93.
We present results of calculations for the fractional energy difference between the bcc and fcc phases present in ordered systems of polystyrene spheres in aqueous suspensions. The theoretical model developed for those systems is an extension of the concept of a Wigner lattice. The interaction between the particles is assumed to be a screened coulomb potential. We conclude that the phase transition occurs when λr5 = 1.05 where λ-1 is the Debye screening length and rs is the radius of the spherical volume of the unitary cell. 相似文献
94.
Alipázaga MV Moreno RG Linares E Medeiros MH Coichev N 《Dalton transactions (Cambridge, England : 2003)》2008,(41):5636-5644
DNA damage was investigated in the presence of sulfite, dissolved oxygen and cobalt(II) complexes with glycylglycylhistidine, glycylhistidyllysine, glycylglycyltyrosylarginine and tetraglycine. These studies indicated that only Co(II) complexed with glycylglycylhistidine (GGH) induced DNA strand breaks at low sulfite concentrations (1-80 microM) via strong oxidants formed in the reaction. In the presence of the other complexes, some damage occurred only in the presence of high sulfite concentrations (0.1-2.0 mM) after incubation for 4 h. In the presence of GGH, Co(II) and dissolved O2, DNA damage must involve a reactive high-valent cobalt complex. The damaging effect was increased by adding S(IV), due to the oxysulfur radicals formed as intermediates in S(IV) autoxidation catalyzed by the complex. SO3 -, HO and H radicals were detected by EPR-spin trapping experiments with DMPO (5,5-dimethyl-1-pyrroline N-oxide). The results indicate that Co(II) binds O2 in the presence of GGH, and leads to the formation of a DMPO-HO adduct without first forming free superoxide or hydroxyl radical, supporting the participation of a reactive high-valent cobalt complex. 相似文献
95.
M.D.G. da Silva L.A. Medeiros A.C. Biazutti 《Journal of Mathematical Analysis and Applications》2007,334(1):701-715
The present work is dedicated to study a unilateral problem relating to the operator
96.
97.
Kirby AJ Medeiros M Oliveira PS Orth ES Brandão TA Wanderlind EH Amer A Williams NH Nome F 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(52):14996-15004
The high rate of spontaneous hydrolysis of tris-2-pyridyl phosphate (TPP) is explained by the activating effects of the non-leaving ("spectator") groups on P-OAr cleavage, and not by intramolecular catalysis. Previous work on phosphate-transfer reactions has concentrated on the contributions to reactivity of the nucleophile and the leaving group, but our results make clear that the effects of the non-leaving groups on phosphorus can be equally significant. Rate measurements for three series of phosphate triesters showed that sensitivities to the non-leaving groups are substantial for spontaneous hydrolysis reactions, although significantly smaller for reactions with good nucleophiles. There are clear differences between triaryl and dialkyl aryl triesters in sensitivities to leaving and non-leaving groups with the more reactive triaryl systems showing lower values for both β(LG) and β(NLG). Intramolecular catalysis of the hydrolysis of TPP by the neighbouring pyridine nitrogens is insignificant, primarily because of their low basicity. 相似文献
98.
Michael J. Silva Alex O. Sanches Luiz F. Malmonge Eliton S. Medeiros Morsyleide F. Rosa Colleen M. McMahan José A. Malmonge 《Macromolecular Symposia》2012,319(1):196-202
Summary: Cellulose nanofibrils (CNF) were extracted by acid hydrolysis from cotton microfibrils and nanocomposites with polyaniline doped with dodecyl benzenesulphonic acid (PANI-DBSA) were obtained by in situ polymerization of aniline onto CNF. The ratios between DBSA to aniline and aniline to oxidant were varied in situ and the nanocomposites characterized by four probe DC electrical conductivity, ultraviolet-visible-near infrared (UV-Vis - NIR) and Fourier-transform infrared (FTIR) spectroscopies and X-ray diffraction (XRD). FTIR and UV-Vis/NIR characterization confirmed the polymerization of PANI onto CNF surfaces. Electrical conductivity of about 10−1 S/cm was achieved for the composites; conductivity was mostly independent of DBSA/aniline (between 2 and 4) and aniline/oxidant (between 1 and 5) molar ratios. X-ray patterns of the samples showed crystalline peaks characteristic of cellulose I for CNF samples, and a mixture of both characteristic peaks of PANI and CNF for the nanocomposites. Field emission scanning electron microscopy (FESEM) characterization corroborated the abovementioned results showing that PANI coated the surface of the nanofibrils. 相似文献
99.
Lucas C. F. Ferreira Everaldo S. Medeiros Marcelo Montenegro 《Annali di Matematica Pura ed Applicata》2013,192(4):539-552
The equation Δu + V(x)u + b(x)u|u| ρ -1 + h(x) = 0 in ${\mathbb{R}^{n}}$ is studied in anisotropic Lebesgue spaces. We assume ${\frac{n-\theta}{n-2} < \rho < \infty}$ , with n ≥ 3 and 0 ≤ θ < 2, which covers the supercritical range. Our approach relies on estimates of the Riesz potential and allows us to consider a wide class of potentials V, including anisotropic ones. The symmetry and antisymmetry of the solutions are also addressed. 相似文献
100.