Gas transport properties of siloxane polyurethanes

Polyurethanes (PUs) were synthesized from toluenediisocyanates (TDIs) and a polymeric diol having polydimethylsiloxane and polyoxyethylene blocks of the ABA type, ended with OH groups. Prepolymers, prepared in toluene solution using ratios [NCO]/[OH] ≥ 2, were crosslinked with triisopropanolamine (TIPA) (ratio [OH]/[NCO] = 1.1) (two-step process). PUs were also obtained with a one-step process using, contemporaneously, TDI, block copolymer, and, as crosslinking agent, TIPA or the glyceride of ε-hydroxyhexanoic acid. Polydimethylsiloxane (PDMSO) was prepared as a reference material. The course of the reaction between block copolymer and TDI was studied by differential scanning calorimetry in the absence and presence of benzoyl chloride (BzCl). Without BzCl, with ratios [NCO]/[OH] > 2, uncontrolled crosslinking side reactions occur. The properties of the PU films obtained with the two methods were studied both for the density of crosslinking and for gas transport properties. The two-step polymers are less crosslinked than the others and are characterized by higher diffusion coefficients and by higher permeability to gases. The permeability order is 10^?9 (N cm³ cm^?1 cm^?1 cm Hg^?1 s^?1) for CH₄, O₂, CO, and N₂ and is 10 times higher for CO₂. The selectivity for the couple O₂/N₂ is higher than that obtained with PDMSO films. Considerable selectivities are shown for the couples CO₂/N₂ and CO₂/CO. © 1995 John Wiley & Sons, Inc.     

RF breast cancer detection employing a noncharacterized vivaldi antenna and a MUSIC‐inspired algorithm

A novel microwave breast cancer detection system consisting of an Evolutionary Global Optimized Vivaldi antenna and an algorithm inspired by MUltiple SIgnal Classification (MUSIC) is presented. Its performance is assessed by using a simplified numerical breast phantom for a number of critical conditions including the presence of fibroglandular tissues. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

SPINE: a domain‐specific framework for rapid prototyping of WBSN applications

Wireless body sensor networks (WBSNs) enable a broad range of applications for continuous and real‐time health monitoring and medical assistance. Programming WBSN applications is a complex task especially due to the limitation of resources of typical hardware platforms and to the lack of suitable software abstractions. In this paper, SPINE (signal processing in‐node environment), a domain‐specific framework for rapid prototyping of WBSN applications, which is lightweight and flexible enough to be easily customized to fit particular application‐specific needs, is presented. The architecture of SPINE has two main components: one implemented on the node coordinating the WBSN and one on the nodes with sensors. The former is based on a Java application, which allows to configure and manage the network and implements the classification functions that are too heavy to be implemented on the sensor nodes. The latter supports sensing, computing and data transmission operations through a set of libraries, protocols and utility functions that are currently implemented for TinyOS platforms. SPINE allows evaluating different architectural choices and deciding how to distribute signal processing and classification functions over the nodes of the network. Finally, this paper describes an activity monitoring application and presents the benefits of using the SPINE framework. Copyright © 2010 John Wiley & Sons, Ltd.     

An automatic pulsed laser microfluorometer with high spatial and temporal resolution

The paper describes an automatic pulsed laser microfluorometer with high spatial and temporal resolution, developed in our laboratories. The instrument consists of: (i) a nitrogen-laser-pumped dye-laser for the excitation of the fluorescence, (ii) a microscope with additional optics to focus the excitation beam on the sample and to collect the fluorescence, (iii) filters or monochromators to select the output wavelength, (iv) a fast photomultiplier tube to detect the signal, and (v) a dual time-scale microprocessor-controlled signal averager for the acquisition and processing of the signal. Examples are given that show the potential of the time-resolved fluorescence microscopy in studying, quantitatively and qualitatively, the properties of fluorescent molecules.     

Evaluation and comparison of cell loss and delay models for ATM multiplexers

Among several models that are available to represent the aggregate cell flow generated by on–off sources at an ATM multiplexer (either at an access or a switching node), the Interrupted Bernoulli Process (IBP) is characterized by particular simplicity and analytical tractability. The superposition of sources individually modeled as an IBP, whose cells enter a common buffer, is considered in this paper. The main goal is to compute approximations of two basic Quality of Service (QoS) indicators, namely, cell loss rate, whose analytical computation has been already presented in previous works, and the rate of cells exceeding a specified delay, whose presentation constitutes the theoretical novelty of the paper. Analytical expressions of these two quantities are given for homogeneous sources, i.e., possessing the same statistical parameters and QoS requirements. The analytical formulation is carefully evaluated by comparing the results obtained with others presented in the literature and with simulation results; in the latter, the actual cell arrival process is generated by means of a Markov Modulated Deterministic Process (MMDP) model of the on–off sources. Several comparisons are performed for different offered loads and by varying the buffer length, which show the effectiveness and the limits of the technique under investigation.     

Optically Inspired Nanomagnonics with Nonreciprocal Spin Waves in Synthetic Antiferromagnets

Integrated optically inspired wave-based processing is envisioned to outperform digital architectures in specific tasks, such as image processing and speech recognition. In this view, spin waves represent a promising route due to their nanoscale wavelength in the gigahertz frequency range and rich phenomenology. Here, a versatile, optically inspired platform using spin waves is realized, demonstrating the wavefront engineering, focusing, and robust interference of spin waves with nanoscale wavelength. In particular, magnonic nanoantennas based on tailored spin textures are used for launching spatially shaped coherent wavefronts, diffraction-limited spin-wave beams, and generating robust multi-beam interference patterns, which spatially extend for several times the spin-wave wavelength. Furthermore, it is shown that intriguing features, such as resilience to back reflection, naturally arise from the spin-wave nonreciprocity in synthetic antiferromagnets, preserving the high quality of the interference patterns from spurious counterpropagating modes. This work represents a fundamental step toward the realization of nanoscale optically inspired devices based on spin waves.     

Effects of supercritical and liquid carbon dioxide extraction on hemp (Cannabis sativa L.) seed oil

The increase in the popularity of hemp-based products is mainly linked to the presence of non-psychoactive cannabinoids that provide relief from aches, pain and anxiety. In this study, hemp seed oils were produced by two innovative and environmentally friendly extraction techniques: supercritical and liquid carbon dioxide (CO₂) extraction. The chemical composition of the two oils was analysed and compared with that of a control oil obtained by solvent (n-hexane) extraction. Both oils obtained by liquid and supercritical CO₂ extraction presented interesting compositions: they contained large amounts of cannabinoids, polyphenols and tocopherols and were less oxidised than the control and contained a large amount of hexanal, which provided a pleasant aroma. The maximum cannabinoid content was found in the oil obtained by liquid CO₂ extraction (71.51 mg of cannabidiol per kg of oil and 113.92 mg of cannabinol per kg of oil). Carotenoids were prevalent in the oil obtained by supercritical CO₂ extraction (61.00 mg kg⁻¹ of oil).     

Source Reconstruction of Atmospheric Releases with Limited Meteorological Observations Using Genetic Algorithms

A genetic algorithm is paired with a Lagrangian puff atmospheric model to reconstruct the source characteristics of an atmospheric release. Observed meteorological and ground concentration measurements from the real-world Dipole Pride controlled release experiment are used to test the methodology. A sensitivity study is performed to quantify the relative contribution of the number and location of sensor measurements by progressively removing them. Additionally, the importance of the meteorological measurements is tested by progressively removing surface observations and vertical profiles. It is shown that the source term reconstruction can occur also with limited meteorological observations. The proposed general methodology can be applied to reconstruct the characteristics of an unknown atmospheric release given limited ground and meteorological observations.     

Use of intelligent sensors and software radio technologies foroptimal design of reconfigurable multimedia surveillance networks

In these last years, the increasing request for security coming from civil society led to intensive exploitation of the most advanced technological tools for solving problems related to remote monitoring of public sites. New-generation multimedia surveillance systems will be characterized by such key topics as distribution of processing capabilities among intelligent sensor and central processing levels, and dynamic reconfigurability of the wireless links thanks to innovative software radio technologies. In this work a joint analysis of such aspects is presented in order to provide optimal design strategies for new-generation multimedia surveillance networks, able to take into account the trade-offs between available computing and communications resources and required performance in terms of correct event detection and real-time processing     

LDPE‐based blends and films stabilized with nonreleasing polymeric antioxidants for safer food packaging

Several novel random copolymers of ethylene and 1‐olefin counits bearing a highly efficient phenolic antioxidant moiety placed at different distances from the polymerizable double bond were prepared in the presence of a metallocene catalyst. These copolymers were melt‐blended with an antioxidant‐free LDPE in an internal batch mixer to obtain innovative materials containing nonreleasing polymeric antioxidants suitable for safer food packaging applications. Blends and films, obtained by compression molding, were tested for their thermal and thermo‐oxidative stability by thermogravimetric analysis both in dynamic and isothermal conditions. Films containing the macromolecular antioxidants showed a longer induction time before O₂ uptake starts and, consequently, a higher degradation temperature than neat LDPE or LDPE containing a low molecular weight commercial additive. Aging tests demonstrated that the new polymeric antioxidants also exert a valid protection against photo‐oxidation. Eventually, migration tests demonstrated the absence of any trace of products containing the antioxidant moiety when the films were kept in contact with a food simulant. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012