998 research outputs found
A multiway approach to analyze metabonomic data: a study of maize seeds development
No full textThe aim of this research was to show that the application of multiway partial least square-discriminant analysis to nuclear magnetic resonance spectra is a valuable tool to analyze metabonomic data of transgenic maize. We evaluated the effects, on the development of seeds. of the introduction of the antisense-mediated downregulation and overexpression of the Rpd3 gene (ZmRpd3) in the genome of a maize inbred line, we identified the metabolites involved in the differentiation between classes of samples, directly integrating the evolution of each metabolic perturbation over time in the model. Major differences were found at the beginning of development, confirming the results obtained by transcript analysis: ZmRpd3 transcripts and proteins accumulate during the initial stage of development, suggesting a role for this gene in cell cycle control. (C) 2007 Elsevier Inc. All rights reserved
Hidden peculiarities in the potential energy time series of a tripeptide highlighted by a recurrence plot analysis: A molecular dynamics simulation.
No full textPermeabilità e compatibilità delle lenti a contatto
No full textGli Autori descrivono le caratteristiche fisiche delle lenti a contatto, la disponibilità di ossigeno per la cornea durante il loro porto, i metodi standard di misura della trasmissibilità e una nuova metodica da loro proposta basata sulla risonanza magnetica nucleare, quindi le misure fisiologiche della permeabilità e della trasmissibilità con alcuni modelli. Gli Autori propongono che è necessario correlare i predittori fisiologici con quelli fisici, al fine di prevenire l’anossia corneale. L’ultima parte del lavoro presenta l’interazione tra LAC e lacrime artificiali mediante uno studio NMR, che pone in risalto l’esigenza di una analisi preventiva tra il farmaco e la lente per evitare o volutamente utilizzare, i cambiamenti fisici indotti sul materiale
Diffusive contribution to permeation of hydrogel contact lenses: theoretical model and experimental evaluation by nuclear magnetic resonance techniques
No full textThe biocompatibility of contact lenses is closely related to their oxygen permeability. In hydrogel lenses, this characteristic can be attributed to the water permeability resulting from a combination of viscous and diffusive fluxes. Hydrogel lenses were studied by means of nuclear magnetic resonance (NMR) relaxation times, resulting in a mathematical model which evaluated the water self-diffusion coefficient as a quantification of the diffusive contribution to permeation. Comparing the results obtained with the data of permeability to oxygen as measured by other techniques, a reasonable agreement was shown for lenses with a higher water content (WC) with respect to lenses with a lower WC: this difference was accounted for by considering the different contribution to permeation. (C) 2001 Elsevier Science Ltd. All rights reserved
CHEMICAL AND/OR BIOMOLECULAR ANALYSIS INTEGRATED SYSTEM AND METHOD FOR MANUFACTURING THE SAME
No full textPriority Data: RM2007A000028 22.01.2007 I
Application of trilinear SLICING to analyse a single relaxation curve
No full textDetermining the time constants and amplitudes of exponential decays from relaxation data is a common task in LF-NMR. In this communication, we present an application of the SLICING algorithm to evaluate its possibilities for solving this problem. The method, originally introduced to compare different samples, is applied here to analyse a single relaxation curve, using the embedding technique. To test this procedure, we acquired data sets from samples of liquids properly separated, and characterized by different relaxation times. The results show a good estimation of parameters, comparable with those obtained applying Marquardt's algorithm, when the components have sufficiently different relaxation times. © 2004 Elsevier Inc. All rights reserved
LF-NMR and multivariate data analysis: compression of data to classify hydrogel contact lenses
No full textHydrogel contact lenses swollen in viscoelastic artificial tears solution have been studied, measuring transversal relaxation times of water molecules using LF-NMR techniques. Data were processed by classical multiexponential fitting, by principal component analysis and by SLICING, a multi-way analysis method. The reason for using multivariate data analysis was not to obtain a better fitting, but rather more effective data description. The single-sample relaxation curves were projected in a space spanned by the loading curves, and in this space it was simpler to compare data. In particular, it contributed to the description of the variability of motion characteristics of the water molecule 'families' contained in the studied samples. Applying multivariate techniques, we were able to group lenses with different Equilibrium Water Content (EWC) and with the same water content but different compositions. Accordingly, we were able to point out that, if the lenses are swollen first in physiological solution and then in viscoelastic artificial tears solution, hydration characteristics remained unchanged in all the studied samples, except for 38% EWC lenses
LF-NMR water self-diffusion and relaxation time measurements of hydrogel contact lenses interacting with artificial tears
No full textThe different swelling properties of ionic and non-ionic lenses, immersed in sodium chloride or artificial tears, were investigated by Low-Field Nuclear Magnetic Resonance (LF-NMR) through relaxation time and self-diffusion coefficient measurements. A new model was developed to estimate the water self-diffusion coefficient inside the lenses, the results of which revealed a different mechanism of interaction for ionic versus non-ionic materials with artificial tears. The consequence of this finding suggests clinical implications
New derivatives of BM 212, a class of antimycobacterial compounds based on the Pyrrole ring as a scaffold
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