Electron beam and UV cationic polymerization of glycidyl ethers – PART I: Reaction of monofunctional phenyl glycidyl ether

Investigations of electron beam (e‐beam) and ultra violet (UV)‐induced cationic polymerization kinetics of a mono‐functional epoxy system, phenyl glycidyl ether (PGE), were conducted using real time in situ near infrared (NIR) spectroscopy. Effects of processing variables such as temperature and dose rate on initiation and propagation rate constants have been assessed. The experimental results and results from a simple mathematical model developed to predict the reaction behavior under continuous irradiation showed very good agreement. This work provides a basis for investigating the cure behavior of more complex and industrially relevant crosslinking epoxy systems where diffusion limitations play an important role as discussed in PART II. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Pyrogallol: an Alternative Trapping Agent in Proanthocyanidins Analysis

The use of pyrogallol as trapping reagent in proanthocyanidin (PA) analysis was investigated. PAs are antioxidants and disease-preventing agents, the efficiency of which depends on their composition and size. Different nucleophilic compounds are usually used for acid-catalyzed depolymerization of proanthocyanidins: benzyl mercaptan, phloroglucinol, and cysteamine. Each nucleophile has different characteristics and typical reaction temperatures that ranges from 50 to 90 °C. Pyrogallol is more reactive than these compounds, so it was possible to apply a minor reaction temperature that was finally reduced from 50 to 30 °C, compared to phloroglucinol, but maintaining a significant yield. The results, compared to those obtained using phloroglucinol as trapping nucleophile, indicated that pyrogallol is an effective and interesting reagent for this analysis.     

Identification and characterisation of water and alkali soluble oligosaccharides from hazelnut skin (Corylus avellana L.)

Hazelnut skins are a good example of agricultural by-product with the potential to become a valuable source of functional ingredients. In this work, the fibre from hazelnut skins was extracted by using water and alkali solution and characterised by a suite of analytical tools (MALDI-FTICR, nano LC-Chip-Q-ToF and gas chromatography). Over thirty complex free oligosaccharides, composed mainly of galacturonic acid and N-acetylgalactosamine, were characterised for the first time in the present study. Their concentration ranged between 16 and 34 mg per g of extract. The oligosaccharides isolated from this agricultural by-product are mainly hexose oligosaccharides (potentially galacto-oligosaccharides,) and xyloglucans. The identified composition could justify the bioactive activity of the extracts, namely prebiotic activity, previously demonstrated.     

The effects of defects in purple AuAl2 thin films

Sputter deposited thin films consisting of the intermetallic phase AuAl₂ are known to display a different color than their bulk counterparts, gray or faint pink, instead of the intense purple the phase is famous for. Only after heat treatment is the typical color apparent. The reason for this behavior is assumed to be point defects in the film, a consequence of the deposition method. Heat treatment at 350 °C of 500 nm thin films results in a steady reduction in defects and the color becomes more intense. Ion irradiation by 3.5 MeV Au⁺ ions with fluences between 10¹² and 5 × 10¹⁵ ions cm^–2 reintroduces point defects in the material and thus gradually removes the color again. Interestingly, the color can be brought back to a very similar shade with subsequent thermal treatments, demonstrating reversibility in the process. The samples were investigated by means of X-ray diffraction, reflectometry, electron backscattered diffraction, scanning electron microscopy, light microscopy, transmission electron microscopy and resistivity measurements to obtain information about the correlation between color and the number of defects within the samples. The measured resistivity values were compared with values calculated using the combined Fuchs–Sondheimer/Mayadas–Shatzkes model. Vacancy concentrations were determined from the difference between the model and the measurements.     

Direct measurement of refractive-index dispersion of transparent media by white-light interferometry

We report on a technique for measuring the refractive indices of nonabsorbing media over a broad spectral range from 0.5 to 5 microm. White-light interferometry based on a double-interferometer system consisting of a fixed Mach-Zehnder interferometer and a Fourier-transform spectrometer is used for direct measurement of the absolute rotation-dependent phase shift induced by an optical element. Refractive index n(lambda) over the whole investigated spectral range is thus obtained directly to an accuracy of 10(-4) without the need for any specific assumption about dispersion. Results for synthetic fused silica are presented and discussed.     

Duration of the effects of intravenous alendronate in postmenopausal women and in patients with primary hyperparathyroidism and Paget's disease of bone

The effect of a single intravenous (i.v.) infusion of 5 mg alendronate was studied in ten patients with Paget's disease, six patients with primary hyperparathyroidism and ten osteopenic postmenopausal women. Urinary hydroxyproline excretion significantly decreased within few days in all patients (from 113 +/- 67.9 to 58 +/- 35 mmol/mol Cr in Paget's disease, from 21.8 +/- 9 to 12.9 +/- 6 mmol/mol Cr in hyperparathyroidism, from 18.7 +/- 9.5 to 8.5 +/- 4.3 mmol/mol Cr in postmenopausal women). In the patients with Paget's disease urinary hydroxyproline remained suppressed over the 6 months of follow-up, whereas it rose toward pretreatment values within 4 and 6 weeks in the patients with primary hyperparathyroidism and in postmenopausal osteopenic women, respectively. Plasma alkaline phosphatase significantly fell only after 4-6 weeks in patients with primary hyperparathyroidism and in Pagetic patients. In the latter group alkaline phosphatase continued to decline thereafter and a plateau became apparent after 2 months. In postmenopausal women the serum alkaline phosphatase remained unchanged. Thus, the same dose of alendronate induces comparable fractional decreases of bone resorption in the three groups of patients, but the effect is persistent only in Paget's disease. This is consistent with the hypothesis that alendronate inhibits osteoclastic activity only at the level of the existing resorption sites. In osteoporotic and primary hyperparathyroid patients, as soon as the treatment is withdrawn, the appearance of new sites of resorption is not inhibited and bone turnover is resumed to pre-treatment values.(ABSTRACT TRUNCATED AT 250 WORDS)     

Web-Based Adaptive Tutoring: An Approach Based on Logic Agents and Reasoning about Actions

In this paper we describe an approach to the construction of adaptive tutoring systems, based on techniques from the research area of Reasoning about Actions and Change.This approach leads to the implementation of aprototype system, having a multi-agent architecture,whose kernel is a set of rational agents,programmed in the logic programminglanguage DyLOG. In the prototype that weimplemented the reasoning capabilities of theagents are exploited both to dynamically buildstudy plans and to verify the correctness ofuser-given study plans with respect to thecompetence that the user wants to acquire.     

In Saccharomyces cerevisiae,protein secretion into the growth medium depends on environmental factors

In the budding yeast Saccharomyces cerevisiae the cell wall, mainly composed of mannoproteins and glucans, constitutes a barrier to protein excretion in the growth medium. In this paper we have studied the effects of different environmental parameters on excretion of Escherichia coli β-galactosidase obtained by exploiting the glucoamylase II signal sequence. Excretion of the unglycosylated β-galactosidase was detectable only in cells grown in rich medium, was affected by temperature (36°C > 30°C >> 24°C) and slightly stimulated by reducing agents. On the contrary, glycosylated proteins, such as α-galactosidase and glucoamylase II, were excreted to a good extent under all tested conditions of medium composition, growth temperature and pH. These data indicate that optimization of environmental parameters may help the excretion of heterologous proteins, offering advantages for protein purification.     

Parametric characterization of the form of the human pupil from blurred noisy images

The fluctuation of the human pupil is an important parameter in order to make non-invasive diagnosis of many different diseases and in several clinical applications. The relevant measurement device, the pupillometer, consists in a CCD camera, which shoots the pupil. We suppose that the measured image is blurred by a Gaussian kernel and corrupted by an additive white noise; moreover an elliptic shape for the pupil is assumed. We here present the extension of a multiscale approach for edge detection to identify some parameters of the pupil: the location of its centre, the length of the semi-axes and the orientation of the corresponding ellipse. The chosen method requires knowledge about the degradation parameters of the assumed model; so we first present a simple but efficient method to determine such quantities for the measured image. Then we apply the edge detection procedure to identify points close to the pupil edge, within a chosen probability. Finally we find the optimal ellipse fitting a suitable subset of the previously detected edge points. Results are presented, with comparisons to other approaches for edge finding.     

Estimation of the cortical connectivity by high-resolution EEG and structural equation modeling: simulations and application to finger tapping data

Today, the concept of brain connectivity plays a central role in the neuroscience. While functional connectivity is defined as the temporal coherence between the activities of different brain areas, the effective connectivity is defined as the simplest brain circuit that would produce the same temporal relationship as observed experimentally between cortical sites. The most used method to estimate effective connectivity in neuroscience is the structural equation modeling (SEM), typically used on data related to the brain hemodynamic behavior. However, the use of hemodynamic measures limits the temporal resolution on which the brain process can be followed. The present research proposes the use of the SEM approach on the cortical waveforms estimated from the high-resolution EEG data, which exhibits a good spatial resolution and a higher temporal resolution than hemodynamic measures. We performed a simulation study, in which different main factors were systematically manipulated in the generation of test signals, and the errors in the estimated connectivity were evaluated by the analysis of variance (ANOVA). Such factors were the signal-to-noise ratio and the duration of the simulated cortical activity. Since SEM technique is based on the use of a model formulated on the basis of anatomical and physiological constraints, different experimental conditions were analyzed, in order to evaluate the effect of errors made in the a priori model formulation on its performances. The feasibility of the proposed approach has been shown in a human study using high-resolution EEG recordings related to finger tapping movements.