Improvement in volume estimation from confocal sections after image deconvolution

The confocal microscope can image a specimen in its natural environment forming a 3D image of the whole structure by scanning it and collecting light through a small aperture (pinhole), allowing in vivo and in vitro observations. So far, the confocal fluorescence microscope (CFM) is considered a true volume imager because of the role of the pinhole that rejects information coming from out-of-focus planes. Unfortunately, intrinsic imaging properties of the optical scheme presently employed yield a corrupted image that can hamper quantitative analysis of successive image planes. By a post-image collection restoration, it is possible to obtain an estimate, with respect to a given optimization criterium, of the true object, utilizing the impulse response of system or Point Spread Function (PSF). The PSF can be measured or predicted so as to have a mathematical and physical model of the image-formation process. Further modelling and recording noise as an additive Gaussian process has used the regularized Iterative Constrained Tykhonov Miller (ICTM) restoration algorithm for solving the inverse problem. This algorithm finds the best estimate iteratively searching among the possible positive solutions; in the Fourier domain, such an approach is relatively fast and elegant. In order to compare the effective improvement in the quantitative image information analysis, we measured the volume of reference objects before and after image restoration, using the isotropic Fakir method.     

Percutaneous Permeation of Topical Phtalocyanine Studied by Photoacoustic Measurements

The purpose of this study was to evaluate the percutaneous permeation of topical hydroxy-(29H,31H-phthalocyaninato)aluminum (PcAlOH) on pig ear skin employing photoacoustic (PA) measurements. The PcAlOH was incorporated in an emulsion with assessed stability parameters of pH and short- and long-term stability tests. Pig skin was prepared through a heat separation technique, and the outer skin of the cartilage was removed with a scalpel. Skin samples were then cut and treated with sodium bromide 2?mol . L^?1 for 6 h at 37?°C. The epidermis layer was washed with purified water, dried, and stored under reduced pressure until use. The skin permeation kinetics were determined by PA measurements as a function of time, performed with an open PA cell developed at Universidade do Vale do Paraíba. Short- and long-term stability tests showed no phase separation. A significant difference was found between the typical times for percutaneous permeation of the emulsion base and the emulsion + PcAlOH. The study showed two absorption transients due to the physical diffusion of molecules in the skin sample. The first is attributed to the penetration of molecules that promptly passed through the lipid barrier, while the second is related to the molecules that had greater difficulty of passing through. This slower component in the absorption curves is attributed to the penetration of PcAlOH, a planar molecule whose percutaneous penetration is more difficult. The study indicates that the formulations containing PcAlOH have stable characteristics and show promising results in absorption into the skin. The presence of the photosensitive agent in the formulation contributed significantly to the larger time constant observed. PA measurements allowed the evaluation of the penetration kinetics of PcAlOH in pig ear skin; the methodology employed may be used in the determination of the percutaneous permeation of phthalocyanines in further studies.     

A COMBINATION OF SUPPORT VECTOR MACHINE AND k-NEAREST NEIGHBORS FOR MACHINE FAULT DETECTION

This article presents a combination of support vector machine (SVM) and k-nearest neighbor (k-NN) to monitor rotational machines using vibrational data. The system is used as triage for human analysis and, thus, a very low false negative rate is more important than high accuracy. Data are classified using a standard SVM, but for data within the SVM margin, where misclassifications are more like, a k-NN is used to reduce the false negative rate. Using data from a month of operations of a predictive maintenance company, the system achieved a zero false negative rate and accuracy ranging from 75% to 84% for different machine types such as induction motors, gears, and rolling-element bearings.     

Influence of interfacial agents on the physicochemical characteristics of binary polyethylene/polyamide 6 and ternary polyethylene/polypropylene/polyamide 6 blends

Binary low-density polythylene/polyamide 6 and ternary low-density polyethylene/polypropylene/polyamide 6 blends were prepared by melt mixing, without and with the addition of two different commercial products [poly(ethylere-co-buthylacrylate-co-maleic anhydride) and poly(ethylene-co-vinylacetate) grafted with maleic anhydride] used as interfacial modifiers. More precisely, the polypropylene was a propylene/ethylene random copolymer, containg 6% by weight of ethylene. The polyamide 6/interfacial agent and polyethylene/ interfacial agent systems were also considered. Differential scanning calorimetry, microscopic observations—together with chemical etchings—and mechanical tests supported the occurrence of strong interactions at the interface, especially when using the buthyl acrylate-based agent. The compatibilizing effect of the interfacial agents was also analyzed in the light of interfacial tension determinations. Eventually, low-density polyethylene modifications induced by compatibilization were studied carrying out WAXD analysis. © 1996 John Wiley & Sons, Inc.     

Characterization of polypropylene–poly(1-butene)–hydrogenated olygo(cyclopentadiene) ternary blends

Ternary blends containing polypropylene (PP), poly(1-butene) (PB), and hydrogenated oligo(cyclopentadiene) (HOCP) have been studied using microscopic calorimetric and dynamic mechanical techniques, with no phase separation having been observed in the melt for all the considered compositions. The morphology of the crystallized blends and spherulite growth rate of the PP component appeared to be influenced by the blend composition. The presence of one or two T_gs revealed by dynamic mechanical thermal analysis (DMTA) on quenched or crystallized blends has suggested that demixing phenomena can occur during the crystallization of the components. The blend composition has been found to affect the overall crystallization rate and the equilibrium melting temperature of the PP component. A parameter describing the enthalpic interactions between the PP component and the diluent fraction evidenced that the addition of HOCP to PP and PB increases the stability of the ternary blend. The above results suggest that the three components can form a miscible blend in the melt. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1659–1665, 1997     

Recent results in color compositing of three-parameter magnetic resonance scans as a preoperative aid to the management of upper limb sarcomas

The phenomenon of induced tolerance to a normally lethal episode of ischaemia by preconditioning with sub-lethal ischaemia has been linked to induction of the 72 kDa heat-shock protein (HSP72). However, a direct correlation between HSP72 expression and ischaemic preconditioning in vivo has not been proven. Using an in vitro model of ischaemia-related neuronal damage we have investigated whether HSP72 protein expression is temporally correlated with subsequent tolerance to a normally lethal ischaemic episode. Organotypic hippocampal slice cultures were maintained in vitro for 14 days before being exposed to hypoxia for 15-180 min. Periods of hypoxia shorter than 60 min did not produce neuronal damage. No HSP72 immunoreactivity was observed in either untreated cultures or in those exposed to hypoxia for 15 min. Following 30 and 45 min hypoxia a significant induction of HSP72 occurred in neurons of both the CA1 and CA3/4 regions of the pyramidal cell layer. A significant number of microglia were positively stained with HSP72. The peak of HSP72 expression occurred 18 h after the induction of hypoxia but remained significantly elevated for 48 h post-hypoxia. Prolonged hypoxia (60 or 180 min) produced a selective lesion of the CA1 pyramidal cell layer which was not associated with an induction of HSP72. Pre-conditioning with 45 min hypoxia 18 h prior to 180 min hypoxia did not reduce the neuronal damage associated with 180 min hypoxia alone. These data strongly suggest that HSP72 does not directly confer tolerance in this in vitro model of ischaemia-related neuronal death.     

The influence of a polymer substrate on the light fastness and isomerisation of some azo dyes

Poly(ethylene terephthalate) films having different morphologies have been coloured with some azo dyes. Isotropic and anisotropic films showed an inversion in dyeing behaviour as well as in light fastness, always at crystallinity β=0.5. We have interpreted the phenomenon in terms of a different localisation of the dye in going from a structure of PET corresponding to a free-volume model to a structure corresponding to a pore model. It was found that polymer morphology strongly affected dye photofading whilst the thermal cis-trans isomerisation of azo dyes in the PET matrix depended only on the amorphous region; below the glass transition temperature isomerisation proceeded in a way that was determined by the effects of restrictions in the mobility of the photochrome itself.     

Cellulosic materials: Structure and enzymatic hydrolysis relationships

Structural and morphological features of four different cellulosic materials have been deeped by X-ray, CP–MAS NMR, water retention, and specific surface area analysis. Hydrolysis time courses of two of these celluloses were followed by employing an enzymatic system consisting of a cellulase from Trichoderma viride and a cellobiase from Aspergillus niger. Experimental results were rationalized on the basis of a methematical model previously verified on the other two substrates. All the celluloses presented the same mechanistic framework involving product inhibitions. The most efficient pretreatment was found to be the dissolution of cellulosic material in the dimethyl sulfoxide–paraformaldehyde system and regeneration with ammonia. This treatment cancelled the memory of the initial structural order.