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Herein, a chitosan/polyamide nanofibers (CPN)-based adsorbent is employed to interpret the adsorption mechanism of two dyes, namely Reactive Black 5 (RB5) and Ponceau 4R (P4R), at different temperatures. Based on experimental results, the adsorption isotherms of RB5 and P4R dyes indicate that the separation process tends to a saturation plateau at high concentration, also suggesting that the dyes adsorption process occurs with the formation of a finite number of layers. To provide a reasonable explanation of the dyes adsorption mechanisms, three statistical physics models are used and discussed. The advanced modelling analysis reveals that the adsorption of both dyes occurs by the formation of two different adsorbed layers on CPN surface. Based on the application of the best statistical physics adsorption model, it was deduced that both dyes were anchored with horizontal and non-horizontal positions on CPN surface depending on temperature, which was concluded by investigation the captured number of dye molecules per CPN adsorbent site during the adsorption process. Based on these theoretical results, it was noted that the adsorption capacities at saturation followed this sequence: Q (P4R) > Q (RB5) for all investigated temperatures (i.e., 222.4, 261.3, 352.8, 482.2 mg/g for P4R and 198.6, 267.7, 288.2, 352.5 mg/g for RB5), indicating that CPN adsorbent was more effective for the P4R dye removal. The adsorption energies are studied to explain the difference in the interactions between dyes and adsorbent surface (P4R-CPN, RB5-CPN), and between these dyes (P4R-P4R, RB5-RB5), indicating that the removal of these adsorbates was based on a physisorption mechanism where a desorption process is possible. Comparing the estimated parameters of the best statistical physics model, it was concluded that both steric and energetic factors are mainly responsible for the adsorption of P4R and RB5 dyes on CPN.

Thin films of metal phthalocyanines (MPc) are known to exhibit excellent physical properties but poorly controlled morphologies. Therefore, the present work seeks to understand the film growth mechanism of a model compound for potentially usable MPc, specifically, copper tetra(3-nitro-5-tert-butyl)phthalocyanine (CuPc*). The Langmuir-Schaefer (LS) technique was applied to prepare a series of CuPc* films under different processing conditions. The film growth was examined by Brewster angle microscopy (BAM) on the water surface and small-angle X-ray scattering (SAXS) from the solid films. Neutron reflectometry (NR) measurements of the water uptake into the films and computer simulation of hydrated CuPc* were performed to substantiate an idea of colloidal MPc-water aggregates as nanoscale precursors of smooth solid films. This idea appears fruitful in terms of materials chemistry.

The pure rotational spectrum of the amidogen radical 15ND2 has been observed between 264 and 1051 GHz with a source-modulation millimetre- and submillimetre-wave spectrometer. A total of 346 transitions were identified, although not all of them were resolved, because of the complexity of the fine and hyperfine structures. The set of spectroscopic parameters determined from the analysis of the spectrum refers to rotational, centrifugal distortion and electron spin-rotation interaction terms. Moreover, the hyperfine constants relative to the electronic spin-nuclear spin interaction for both deuterium and nitrogen nuclei and to the nuclear rotation–nuclear spin interaction for nitrogen were also successfully fitted. This work provides the first laboratory observation and spectroscopic characterization of the fully substituted isotopologue of the astrophysically important species NH2.

著者人数: 23名, Accepted: 2018-03-29, 資料番号: SA1180194000

In this paper, we thoroughly review all analytical solutions (both exact and approximate) presented to date in the literature for evaluation of voltages induced on a lossless horizontal conductor, placed over an infinite-conductivity ground, and excited by an external field produced by either a step function or a linearly rising current, moving unattenuated and undistorted along a vertical lightning channel. We also obtain the exact analytical solution for the step-function current case in the time domain via development in the s -domain. To date, there had been three attempts to obtain such solution, all of which yielding incorrect results.

An electric interfacial layer is created when the mobile ions or charged nanoparticles of an electrolyte interact with a surface of an extended charged object. The competition between electrostatic attraction and translational entropy loss of the mobile nanoparticles results in a diffuse interfacial layer of nanoparticles close to the charged surface. Due to its simplicity and transparency first wide spread theoretical description of the electric interfacial layer was the Poisson-Boltzmann theory. Numerous improvements were applied that account for charge-charge correlations, steric effects and solvent properties. The present article focuses on spherical mobile nanoparticles which have charge distributed over the surface and have finite size. The nanoparticles are sandwiched between two parallel like-charged walls. We perform the minimization of an appropriate free energy functional, which leads to a non-linear integro-differential equation for the electrostatic potential that is solved numerically. Our model predicts condensation of nanoparticles to oppositely charged surface. For highly charged surfaces and nanoparticles of finite size we observed big differences in the volume charge density profiles between soft and hard spheres. The theoretical predictions are in a good agreement with Monte Carlo simulations.

A novel low-cost surface plasmon resonance (SPR) platform has been tested, for the first time, to monitor the interaction between a molecularly imprinted polymer (MIP) and a small molecule as the substrate. As a proof of principle, the considered MIP was specific for furfural (2-FAL, MW = 96.4), so that the possibility of using the new device for detection of 2-FAL in aqueous media was investigated. For the sake of comparison a sensor based on the same MIP specific for 2-FAL deposited on an SPR platform in a D-shaped plastic optical fiber (POF), which has been previously demonstrated to well perform for different analytes, has been considered too. The experimental results showed good performances of the novel platform for chemical sensing based on MIP as receptor in terms of selectivity, sensitivity and figure of merit (FOM). The limit of detection (LOD) of this simple and low-cost SPR sensor system is about 0.03 ppm, completely comparable to that of previously proposed devices based on SPR in a D-shaped POF (about 0.05 ppm), but with the advantage of an easier and more reproducible preparation procedure.

Water kept in contact with cellulose has not been a “juicy” research topic until now. This is surprising because cellulose is a major component of the cell walls in green plants. It is also a common material used in many artificial systems, e.g., filters. In this work, we review some of our experimental results and show that iteratively bringing cellulose (cotton wool) in contact with pure water endows the water with some unforeseen properties. For example, the liquid left over after removing the cellulose is optically active, i.e., mirror symmetry breaking was triggered during temporary contact of bulk water with a natural polymer. (Here and in the following, by “mirror” symmetry we actually mean “chiral” symmetry). Moreover, this leftover liquid fluoresces after irradiation with ultraviolet light. These properties are neither attributable to impurities released by the inert polymer nor to organic- or bio-contaminants, as our state-of-the-art analytical techniques show. These techniques include gel electrophoresis, Matrix-Assisted Laser Desorption/Ionization Time of Flight (MALDI-TOF) and Gas Chromatography both coupled with Mass Spectrometry. Instead, the properties are attributable to stabilization of interfacial water adjacent to hydrophilic membranes. Our findings have implications for processes in water flowing adjacent to cellulose, in particular enantioselective processes. Such processes play critical roles in many bio-systems and technologies. Thus, our study indicates that water iteratively brought in contact with cellulose merits intensive research.

The effects of moisture on the electrical properties of epoxy molding compounds containing high quantities of silica filler microparticles have been investigated by means of dielectric spectroscopy, steady-state conductivity and pulsed electro-acoustic space charge measurements. It has been shown that the presence of water at the filler/epoxy interfacial areas affects the low-frequency dielectric response of the materials and significantly increases their electrical conductivity, especially at higher temperatures. In addition, in presence of moisture, space charge measurements have shown the accumulation of heterocharges which significantly increase the electric field at the electrodes. These aspects are of primary importance, as the electrical properties of the encapsulation materials strongly influence the space charge distribution in high voltage devices.

The most relevant transport features of doped diamond-like carbon (DLC) films have been implemented in a TCAD setup to provide a theoretical tool to assess the reliability expectations for high-voltage device passivation. Starting from the band structure and boundary conditions of a metal-insulator-semiconductor (MIS) device, trap states in the bandgap have been used to determine the characteristics of differently doped DLC layers against experiments. The role of the DLC as a passivation layer on top of the bevel termination of a high-voltage diode has been studied and compared with experiments. The breakdown voltage is significantly influenced by the properties of the DLC as clearly explained by the TCAD simulation results.

We report on the development of thermal kinetic inductance detectors (TKIDs) suitable to perform X-ray spectroscopy measurements. The aim is to implement MKIDs sensors working in thermal quasi-equilibrium mode to detect X-ray photons as pure calorimeters. The thermal mode is a variation on the MKID classical way of operation that has generated interest in recent years. TKIDs can offer the MKIDs inherent multiplexibility in the frequency domain, a high spatial resolution comparable with CCDs, and an energy resolution theoretically limited only by thermodynamic fluctuations across the thermal weak links. Microresonators are built in Ti/TiN multilayer technology with the inductive part thermally coupled with a metal absorber on a suspended SiN membrane, to avoid escape of phonons from the film to the substrate. The mid-term goal is to optimize the single-pixel design in terms of superconducting critical temperatures, internal quality factors, kinetic inductance and spectral energy resolution. The final goal is to realize a demonstrator array for a next generation thousand pixels X-ray spectrometer. In this contribution, the status of the project after one year of developments is reported, with detailed reference to the microresonators design and simulations and to the fabrication process.

In order to work properly, the X-ray Integral Field Unit of the ATHENA mission requires a set of thermal filters that block the infrared radiation, preventing it to reach the detector. Each filter will be mounted and thermally anchored onto a shield of the multistage cryostat and will be kept at the specific temperature of the stage. On the other hand, the filters partially absorb X-rays, and their transmittance has to be carefully characterized. The effect of temperature on the absorption edges of the elements that make up the filters has not been investigated yet. Here, we report the results of a preliminary run on the optical transmission data around the edges of C, N, and O at different temperatures for a selected test sample with 500 nm of polyimide and 100 nm of aluminum. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.

Over the last few years, there has been a growing interest toward the use of superconducting microwave microresonators operated in quasi-thermal equilibrium mode, especially applied to single particle detection. Indeed, previous devices designed and tested by our group with X-ray sources in the keV range evidenced that several issues arise from the attempt of detection through athermal quasiparticles produced within direct strikes of X-rays in the superconductor material of the resonator. In order to prevent issues related to quasiparticles self-recombination and to avoid exchange of athermal phonons with the substrate, our group focused on the development of thermal superconducting microresonators. In this configuration, resonators composed of multilayer films of Ti/TiN sense the temperature of an absorbing material. To maximize the thermal response, low-critical-temperature films are preferable. By lowering the critical temperature, though, the maximum probing power bearable by the resonators decreases abruptly because of the weakening of the electron–phonon coupling. A proper compromise between the value of critical temperature (and hence sensitivity to energy deposition) and readout power bearable by the device has to be found in order to avoid signal-to-noise ratio degradation. In this contribution, we report the latest measurement of the electron–phonon coupling.

In this paper, we present a new solution for the evaluation of the horizontal electric field in the presence of finitely conducting ground in the time domain. The solution is general, numerically robust, and overcomes the problems related to previously proposed approaches.

The increasing constraints in the miniaturization of modern electronic devices is driving the search for new high-k dielectric materials. Rare-earth transition metal oxides are very interesting because of the large values of dielectric constant observed in bulk samples. Here, we report on a comparison among the dielectric properties of yttrium copper titanate (YCTO) thin films and those of commonly used dielectrics such as SiO2 and MgO, grown in similar device structures. The YCTO permittivity was found to depend strongly on the oxygen pressure during deposition and can reach values even higher than those reported in bulk YCTO with good performances in terms of losses.

In this work, we investigate the possibility of employing graphene field effect transistors, specifically designed for microwave applications, as infrared detectors for telecom applications. Our devices have been fabricated on a sapphire substrate employing CVD-grown transferred graphene. The roles of both the gate dielectric and the DC bias conditions have been evaluated in order to maximize the infrared generated signal through an experimental investigation of the signal-to-noise ratio dependence on the transistor operating point.

Single crystals of PbMoO 4 were studied by means of light-induced electron paramagnetic resonance (EPR) and wavelength resolved thermally stimulated luminescence (TSL). The work is focused on the electron self-trapped at the (MoO 4 ) 2- complex. Detailed analysis of the EPR spectra of this complex allowed to determine a set of spin-Hamiltonian parameters including g factor and the 95,97 Mo, 207 Pb hyperfine tensors further used in calculations performed in terms of crystal field and LCAO-MO theories. They have shown a significant overlap of the Mo 5 d 1 and 6 s 6 p ligand lead orbitals. The contributions of oxygen and lead to the molecular orbitals with an electron trapped at the (MoO 4 ) 3- complex were about 14% and 38%, respectively. The decay of the molybdenum center EPR intensity with annealing temperature provided information about thermal stability of the center, which thermally destroys already at 40 K. Trap depth and frequency factor, E t = 0.05 eV, and f 0 = 10 4 s −1 , have been determined. The TSL glow curve displays two overlapping peaks in the 40–50 K temperature region, corresponding to the disappearance of the EPR signal from the (MoO 4 ) 3- center. By partial cleaning technique and initial rise method it is shown that the lower temperature peak is related to a trap with thermal parameters similar to those determined for the (MoO 4 ) 3- center. This allows to correlate it to the thermal destruction of the (MoO 4 ) 3- center. The obtained results are discussed in a broader frame of charge trapping mechanism in all the family of tungstate and molybdate-based single crystals.

Thermal conductivity is one of the key properties for the application of phase change materials in nonvolatile memories. In this work we compute the mode Grüneisen parameters of the phase change compound GeTe by means of density-functional perturbation theory. The Grüneisen parameters are then used to estimate the bulk thermal conductivity with a phenomenological formula (Slack in Solid State Phys 34:1–71, 1979). This estimate is compared with the full solution of the Boltzmann Transport Equation we obtained in a previous work within the same theoretical framework. This comparison allowed us to validate the phenomenological formula also for the prototypical phase change compound GeTe.

We report on the experimental and theoretical infrared spectrum of the C2H...‹…CO2 complex. This complex was prepared by UV photolysis of propiolic acid (HC3OOH) in argon and krypton matrices. The experimental bands of C2H in the C2H...CO2 complex are blue-shifted from those of the C2H monomer. The calculations on the C2H...‹…CO2 structures were performed at the RMP2/aug-cc-pVTZ level. The relative stability of the complex structures was evaluated by using the RCCSD(T)/aug-cc-pVQZ level. To simulate the spectrum of the C2H...CO2 complex, we developed the theoretical approach used earlier for the C2H monomer. Based on the calculations, the main experimental bands of the C2H...CO2 complex are assigned to the most stable parallel structure. Almost all the strong bands predicted by theory (with intensities >30 km mol−1) are observed in the experiment. To our knowledge, it is the first study of the effect of noncovalent interactions on vibronic transitions and the first report on an intermolecular complex of the C2H radical.

This paper reports the results of a study on the determination of the protonation constants of MoO42−, in NaClaq, NaNO3aq, KClaq, at different ionic strengths (0&nbsp

Boosted by the progresses in nano-optics, highly sensitive and label-free optical transducers for sensing applications have been proposed over the last years. Among them, plasmonic nanoparticle based transducers have had a great success because their resonant behavior is extremely sensitive to the changes of the local surrounding environment, being interesting candidates for real-time measurements and diagnoses. Here, we propose the employment of the core-shell super-spherical nanoparticle to design new sensing devices. We demonstrate that, thanks to this particular geometry, a sensor working in the visible spectrum may exhibit an higher sensitivity with respect to all the conventional solutions currently adopted in the field. The analysis is conducted by developing an analytical model for the polarizability of the core-shell super-spherical particle and verified through a proper set of numerical experiments. Finally, the sensing performances of the core-shell super-spherical nanoparticle are discussed and compared with the state-of-the-art optical sensors working in the same frequency range.

We verified the insertion effect of a cyclic prefix (CP) in an all-optical fractional orthogonal frequency division multiplexing (FrOFDM) system. CP is an essential technique for reducing inter-channel interference in conventional OFDM. Because a FrOFDM signal is generated by a fractional Fourier transform, which is a generalization of the Fourier transform, a CP is also effective for a FrOFDM signal. The measured bit error rate of a 4×10 Gbit/s DBPSK all-optical FrOFDM system showed that the CP improves the signal quality even if the performance of the time gate is insufficient.

Infrared reflectography is an imaging technique used to visualize the underdrawings of ancient paintings; it relies on the fact that most pigment layers are quite transparent to infrared radiation in the spectral band between 0.8 μm and 2.5 μm. InGaAs sensor cameras are nowadays the most used devices to visualize the underdrawings but due to the small size of the detectors, these cameras are usually mounted on scanning systems to record high resolution reflectograms. This work describes a portable scanning system prototype based on a peculiar spherical scanning system built through a light weight and low cost motorized head. The motorized head was built with the purpose of allowing the refocusing adjustment needed to compensate the variable camera-painting distance during the rotation of the camera. The prototype has been tested first in laboratory and then in-situ for the Giotto panel “God the Father with Angels” with a 256 pixel per inch resolution. The system performance is comparable with that of other reflectographic devices with the advantage of extending the scanned area up to 1 m × 1 m, with a 40 min scanning time. The present configuration can be easily modified to increase the resolution up to 560 pixels per inch or to extend the scanned area up to 2 m × 2 m.

Infrared (IR) light propagation in semicrystalline polymers involves mechanisms such as reflection, transmission, absorption and internal scattering. These different rates determine either the interaction mechanism, either the temperatures reached in the IR heating processes. Consequently, the knowledge of these rates is fundamental in the development of IR heating processes in order to avoid the polymer's damage and to increase the process energy efficiency. Aim of this work is to assess a simple procedure to determine the rates of absorbed, reflected, transmitted and scattered energy in the case of an unfilled High Density Polyethylene (HDPE) plate. Experimental tests were performed by exposing a HDPE plate, 3 mm in thickness, to a diode laser source, working at the fundamental wavelength of 975 nm. The transmitted power was measured by power meter, the reflected one by applying the Beer–Lambert law to sample of different thickness. IR thermal images were adopted to measure the absorbed ratio. The scattered ratio was measured by energetic balance, as difference between the incoming power and the other ratios. Finally, IR thermal images were adopted to measure the scattered ratio and to validate the procedure.

The high-harmonic generation from a structured quantum ring (SQR) driven by an intense laser field is presented within the single active electron approximation. The spectrum is studied by varying the symmetry of the physical system. The standard SQR (six identical and equidistant dots in a ring) presents a 60° rotational symmetry, that in this work is broken, moving or changing only one potential hole. We find that careful designed breaking of the geometrical symmetry of the SQR opens the possibility of controlling the characteristics of the harmonic lines such as intensity and polarization. HHG analysis of the emission spectrum performed through a Morlet wavelet, shows that the high-frequency emission occurs during short time intervals.

Brillouin scattering properties of silica fibers at 850-nm wavelength were experimentally investigated using a Brillouin optical time-domain analysis scheme. In the single-mode 780-HP fiber, the Brillouin frequency shift (BFS) and full width at-half maximum of the Brillouin gain spectrum were found to be ~19795 and 90 MHz, respectively. The estimated peak Brillouin gain is 0.32 (mW) -1 . The temperature and strain dependences of BFS were determined as well. Distributed sensing capability was demonstrated at a minimum spatial resolution of 1.5 m and a fiber length of 100 m. As a proof-of-principle, the temperature and strain dependences of the BFS in SFM-28 fiber have been determined at 850- and 1550-nm wavelengths, suggesting its possible use for temperature/strain discrimination.

We investigate electromagnetic propagation in uniaxial dielectrics with a transversely varying orientation of the optic axis, the latter staying orthogonal everywhere to the propagation direction. In such a geometry, the field experiences no refractive index gradients, yet it acquires a transversely-modulated Pancharatnam-Berry phase, that is, a geometric phase originating from a spin-orbit interaction. We show that the periodic evolution of the geometric phase versus propagation gives rise to a longitudinally-invariant effective potential. In certain configurations, this geometric phase can provide transverse confinement and waveguiding. The theoretical findings are tested and validated against numerical simulations of the complete Maxwell's equations. Our results introduce and illustrate the role of geometric phases on electromagnetic propagation over distances well exceeding the diffraction length, paving the way to a whole new family of guided waves and waveguides which do not rely on refractive index tailoring., 16 pages, 4 figures

A family of fluorinated imidazolium salts showing liquid-crystalline properties in a wide temperature range was developed. These fluorinated ionic liquid crystals, due to their intrinsic hydrophobicity, high thermal stability and good conductivity, are suitable candidates to be used as electrolytes in electrochemical devices such as bye Sensitized Solar Cell (DSSC) or lithium batteries. (C) 2016 Elsevier B.V. All rights reserved.

Walls thermal transmittance value (U-value) is essential to identify the performance of a wall and it is used for the energy labeling procedure. If on one hand the heat-flow meter can measure heat fluxes across its plate giving back the wall's U-value, on the other hand, if air temperatures and wall's inner surface temperatures are measured, it is necessary to set the total heat transfer coefficient value in order to calculate the heat fluxes. Many correlations were developed in scientific literature to quantify the convective heat transfer coefficient and it is possible to distinguish similarity based and experimentally ones. In this paper, the actual total heat transfer coefficients in different case studies were obtained by measuring the physical parameters that are needed to define them. Convective and radiative contributions were separately evaluated and, finally, actual convective heat transfer coefficients were compared with the same coefficients obtained by applying the correlations available in literature and with the constant value suggested by the Standard. The aim of this study is to analyze the differences between the various coefficients values and their influence on the thermal transmittance evaluation, in order to better understand the existing correlations and the UNI EN ISO 6946 applicability. This is an initial part of a research which aims to provide an overall more accurate representation of the building behavior, forthcoming developments will deal with the analysis of heat transfer on the outer side of walls.

The Compton effect is a potential ionization mechanism of atoms. It produces vacancies in inner shells that are filled with the same mechanism of atomic relaxation as the one following photo-absorption. This contribution to X-ray fluorescence emission is frequently neglected because the total Compton cross-section is apparently much lower than the photoelectric one at useful X-ray energies. However, a more careful analysis suggests that is necessary to consider single shell cross sections (instead of total cross sections) as a function of energy. In this article these Compton cross sections are computed for the shells K, L1-L3 and M1-M5 in the framework of the impulse approximation. By comparing the Compton and the photoelectric cross-section for each shell it is then possible to determine the extent of the Compton correction to the intensity of the corresponding characteristic lines. It is shown that for the K shell the correction becomes relevant for excitation energies which are too high to be influent in X-ray spectrometry. In contrast, for L and M shells the Compton contribution is relevant for medium-Z elements and medium energies. To illustrate the different grades of relevance of the correction, for each ionized shell, the energies for which the Compton contribution reaches the extent levels of 1, 5, 10, 20, 50 and 100% of the photoelectric one are determined for all the elements with Z = 11–92. For practical applications it is provided a simple formula and fitting coefficients to compute average correction levels for the shells considered.

Tears are exceptionally rich sources of information on the health status of the eyes, as well as of whole body functionality, due to the presence of a large variety of salts and organic components whose concentration can be altered by pathologies, eye diseases and/or inflammatory processes. Surface enhanced Raman spectroscopy (SERS) provides a unique method for analyzing low concentrations of organic fluids such as tears. In this work, a home-made colloid of gold nanoparticles has been used for preparing glass substrates able to efficiently induce an SERS effect in fluid samples excited by a He&ndash, Ne laser ( &lambda, = 633 nm). The method has been preliminary tested on Rhodamine 6G aqueous solutions at different concentrations, proving the possibility to sense substance concentrations as low as few &mu, M, i.e., of the order of the main tear organic components. A clear SERS response has been obtained for human tear samples, allowing an interesting insight into tear composition. In particular, aspartic acid and glutamic acid have been shown to be possible markers for two important human tear components, i.e., lactoferrin and lysozyme.

This paper presents the design and calibration of a new force/tactile sensor for robotic applications. The sensor is suitably designed to provide the robotic grasping device with a sensory system mimicking the human sense of touch, namely, a device sensitive to contact forces, object slip and object geometry. This type of perception information is of paramount importance not only in dexterous manipulation but even in simple grasping tasks, especially when objects are fragile, such that only a minimum amount of grasping force can be applied to hold the object without damaging it. Moreover, sensing only forces and not moments can be very limiting to securely grasp an object when it is grasped far from its center of gravity. Therefore, the perception of torsional moments is a key requirement of the designed sensor. Furthermore, the sensor is also the mechanical interface between the gripper and the manipulated object, therefore its design should consider also the requirements for a correct holding of the object. The most relevant of such requirements is the necessity to hold a torsional moment, therefore a soft distributed contact is necessary. The presence of a soft contact poses a number of challenges in the calibration of the sensor, and that is another contribution of this work. Experimental validation is provided in real grasping tasks with two sensors mounted on an industrial gripper.

The equations governing nonlinear light beam propagation in nematic liquid crystals form a [Formula: see text]-dimensional system consisting of a nonlinear Schrödinger-type equation for the electric field of the wavepacket and an elliptic equation for the reorientational response of the medium. The latter is “nonlocal” in the sense that it is much wider than the size of the beam. Due to these nonlocal, nonlinear features, there are no known general solutions of the nematic equations; hence, approximate methods have been found convenient to analyze nonlinear beam propagation in such media, particularly the approximation of solitary waves as mechanical particles moving in a potential. We review the use of dynamical equations to analyze solitary wave propagation in nematic liquid crystals through a number of examples involving their trajectory control, including comparisons with experimental results from the literature. Finally, we make a few general remarks on the existence and stability of optically self-localized solutions of the nematic equations.

LoRaWAN is one of the most promising standards for long-range sensing applications. However, the high number of end devices expected in at-scale deployment, combined with the absence of an effective synchronization scheme, challenge the scalability of this standard. In this paper, we present an approach to increase network throughput through a Slotted-ALOHA overlay on LoRaWAN networks. To increase the single channel capacity, we propose to regulate the communication of LoRaWAN networks using a Slotted-ALOHA variant on the top of the Pure-ALOHA approach used by the standard; thus, no modification in pre-existing libraries is necessary. Our method is based on an innovative synchronization service that is suitable for low-cost wireless sensor nodes. We modelled the LoRaWAN channel with extensive measurement on hardware platforms, and we quantified the impact of tuning parameters on physical and medium access control layers, as well as the packet collision rate. Results show that Slotted-ALOHA supported by our synchronization service significantly improves the performance of traditional LoRaWAN networks regarding packet loss rate and network throughput., Sensors, 19 (4), ISSN:1424-8220

The wide availability of sensing modules and computing capabilities in modern mobile devices (smartphones, smart watches, in-vehicle sensors, etc.) is driving the shift from mote-class wireless sensor networks (WSNs) to the new era of crowdsensing WSNs. In this emerging paradigm sensors are no longer static and homogeneous, but are rather worn/carried by people or cars. This results in a new type of wide-area WSN—crowd-based and overlaid on top of heterogeneous communication technologies—that paves the way for very innovative applications. To this aim, the positioning of mobile devices operating in the network becomes crucial. Indeed, the pervasive, almost ubiquitous availability of smart devices brings unprecedented opportunities but also poses new research challenges in their precise location under mobility and dense-multipath environments typical of urban and indoor scenarios. In this paper, we review recent advances in the field of wireless positioning with focus on cooperation, mobility, and advanced array processing, which are key enablers for the design of novel localization solutions for crowdsensing WSNs.

In this paper, a frequency-signature Radio-Frequency Identification (RFID) chipless tag for wearable applications is presented. The results achieved for a fully-textile solution guaranteeing a seamless integration in clothes are reported and discussed. The proposed tag consists of two planar monopole antennas and a 50 &Omega, microstrip line loaded with multiple resonators. In order to achieve a compact size, the resonators are slotted on the ground plane of the microstrip line. As for the antennas, the same geometry was exploited for both the TX and the RX tag antenna. In particular, it consists of a proximity fed planar monopole on a ground plane. The selected geometry guarantees easy integration with the multi-resonator structure. Numerical and experimental data referring to a 2-bit implementation are presented and discussed. For fabricating all the prototypes, a layer of pile was used as a substrate, while an adhesive non-woven conductive fabric was exploited for the fabrication of the conductive parts. Experimental tests demonstrate that although the performance of the final device strongly depends on the properties of the used materials and on the imperfections of the fabrication process, the proposed frequency-signature RFID chipless tag is suitable for wearable applications, such as anti-counterfeiting systems and laundry labels.

Cloud radio access networks (C-RANs), relying on network function virtualization and software-defined networking (SDN), require a proper placement of baseband functionalities (BBUs) to reach full coverage of served areas and service continuity. In this context, network resources can be shared and orchestrated to meet the flexibility required by a dynamically evolving environment. Different methodologies, based on analytical formulation or heuristic algorithms, can be applied to achieve suitable trade-offs among cost components. This paper considers both centralized and distributed algorithms to obtain BBU hotel placement in C-RAN and compares their performance, scalability and adaptability to evolving scenarios. As expected, the results obtained with the distributed approach are sub-optimal, but very close, in most cases, to the optimal solutions obtained with a centralized algorithm based on integer linear programming. In addition to off-loading the SDN orchestrator, the distributed approach, differently from the centralized one, is shown to be able to cope with the evolution of the C-RAN topology with limited incremental changes in the original placement. The limits of the centralized approach in terms of scalability that the distributed approach is able to overcome are also evidenced.

The effect of sulfonated graphene oxide (SGO) on the interaction mechanism of polyvinyl alcohol and poly (4-styrene sulfonic acid) (PVA/PSS) matrix is investigated in this paper. Pure PVA/PSS, PVA/PSS/graphene oxide (GO) and PVA/PSS/SGO nanocomposites are prepared by the freeze-thaw method. The glutaraldehyde (GLA) is used as a crosslinking agent to improve the stability of the materials. The sulfonation of GO is confirmed by the Fourier transform infrared spectroscopy (FTIR) and X-ray fluorescence spectrometry (XRF) analyses. The fully exfoliation of GO is recognized using a transmission electronic microscopy (TEM). All the nanocomposites are characterized using FTIR, UV–Vis spectroscopy and scanning electron microscopy (SEM). A theoretical molecular simulation of the nanocomposites systems is performed to elucidate the different energies associated with the interfacial interactions. A strong interaction energy is determined due to the presence of different functional groups within the systems. The hydrogen bonding of the OH, COOH, SO3H and C-O-C groups show a EH-bond energy for the PVA/PSS/SGO system (−735.39 kcal/mol) which is higher than the corresponding of PVA/PSS/GO (−686.86 kcal/mol). The effect of the sulfonated group is more significant than that of the carboxylic group, due to both the higher polarity and higher electronegativity of the sulfonic acid group.

An office chair for analyzing the seated posture variation during the performance of a stress-level test is presented in this work. To meet this aim, we placed a set of textile pressure sensors both on the backrest and on the seat of the chair. The position of the sensors was selected for maximizing the detection of variations of user&rsquo, s posture. The effectiveness of the designed system was evaluated through an experiment where increasing stress levels were obtained by administering a Stroop test. The collected results had been analyzed by considering three different time intervals based on the difficulty level of the test (low, medium, and high). A transition analysis conducted on postures assumed during the test showed that participants reached a different posture at the end of the test, when the cognitive engagement increased, with respect to the beginning. This evidence highlighted the presence of movement presumably due to the increased cognitive engagement. Overall, the performed analysis showed the proposed monitoring system could be used to identify body posture variations related to different levels of engagement of a seated user while performing cognitive tasks.

The dynamic response of gas sensors based on poly(3-hexylthiophene) (P3HT) nanofibers (NFs) to gaseous acetone was assessed using a setup based on flow-injection analysis, aimed at emulating actual breath exhalation. The setup was validated by using a commercially available sensor. The P3HT NFs sensors tested in dynamic flow conditions showed satisfactory reproducibility down to about 3.5 ppm acetone concentration, a linear response over a clinically relevant concentration range (3.5-35 ppm), excellent baseline recovery and reversibility upon repeated exposures to the analyte, short pulse rise and fall times (less than 1 s and about 2 s, respectively) and low power consumption (few nW), with no relevant response to water. Comparable responses’ decay times under either nitrogen or dry air suggest that the mechanisms at work is mainly attributable to specific analyte-semiconducting polymer interactions. These results open the way to the use of P3HT NFs-based sensing elements for the realization of portable, real-time electronic noses for on-the-fly exhaled breath analysis.

While the undisturbed Earth&rsquo, s magnetic field represents a fundamental information source for orientation purposes, magnetic distortions have been mostly considered as a source of error. However, when distortions are temporally stable and spatially distinctive, they could provide a unique magnetic landscape that can be used in different applications, from indoor localization to sensor fusion algorithms for attitude estimation. The main purpose of this work, therefore, is to present a method to characterize the 3D magnetic vector in every point of the measurement volume. The possibility of describing the 3D magnetic field map through Thin Plate Splines (TPS) interpolation is investigated and demonstrated. An algorithm for the simultaneous estimation of the parameters related to magnetometer calibration and those describing the magnetic map, is proposed and tested on both simulated and real data. Results demonstrate that an accurate description of the local magnetic field using TPS interpolation is possible. The proposed procedure leads to errors in the estimation of the local magnetic direction with a standard deviation lower than 1 degree. Magnetometer calibration and magnetic field mapping could be integrated into different algorithms, for example to improve attitude estimation in highly distorted environments or as an aid to indoor localization.

The specific interactions of water molecules with the tripeptide glutathione are investigated by UV Resonance Raman spectroscopy taking advantage of its sensitivity and selectivity. The peptide-solvent interactions at different chemical sites of glutathione, i.e. the peptide backbone and the side groups of the molecule, are investigated. With the aim of gaining new insights on the mechanism regulating the hydration of glutathione, intimately related to its biological functionality, the spectra of the tripeptide solutions are examined as a function of different concentration, pH and temperature. The Amide and the OH stretching spectral regions result very sensitive to the variations of the explored experimental parameters. Our observations provide a picture of the hydrogen-bonding network around glutathione. The number and the strength of hydrogen bonds increase in the deprotonated form of tripeptide that exhibits also a more marked capacity in decreasing the intermolecular order of water in its hydration shell. According to this view, a progressive reduction in the strength of hydrogen bond interactions on amide sites is probed upon the increment of thermal motion, accompanied by conformational changes involving the trans-cis isomerization of glutathione.

This review covers several aspects of microfluidic devices used for culturing and monitoring of both adherent and non-adherent cells, including a multitude of applications. A comparison of available platforms with high throughput analysis, automation capability, interface to sensors and integration, is reported. Aspects, such as operational versatility of the devices, are scrutinized in terms of their analytical efficacy. It is found that due to multi-functionality capability of modern microfluidics, there is big amount of experimental data obtainable from a single device, allowing complex experimental control and efficient data correlation, particularly important when biomedical studies are considered. Hence several examples on cell culture and monitoring are given in this review, including details on design of microfluidic devices with their distinctive technological peculiarities.

A composite system made of poly( l -lactic acid) (PLLA) and graphene nanoplatelets (GNP) was investigated by Raman and FTIR spectroscopy. Two compositions were prepared and characterized in comparison to the pristine polymer: they contained, respectively, 0.25 and 0.75 wt% of the nanofiller. The study was focused on the morphological properties of the system, and, in particular, on the level of dispersion and the homogeneity obtainable with the adopted preparation protocol. Furthermore, the possible molecular interactions taking place between the nanofiller and the polymer matrix were considered. Both the above issues were investigated by confocal Raman spectroscopy, with the aid of first-principle calculations to strengthen the spectral interpretation. Finally, the effect of the nanofiller on water diffusion was investigated by time-resolved FTIR spectroscopy, which provided accurate equilibrium and kinetic data, as well as molecular level information on the penetrant-to-substrate interactions. It was found that, for a 0.25 wt% composition, the adopted preparation protocol allowed us to achieve a dispersion at the level of single nanoplatelets, while for a 0.75 wt% composition, the GNP's aggregate into a co-continuous phase. PLLA/GNP interactions were detected by Raman spectroscopy, producing a detectable perturbation of the PLLA conformational equilibrium. Both the diffusivities and the equilibrium water uptake were found to decrease significantly by increasing the filler content.

A theoretical study of phenol adsorption on microwave-assisted activated carbons has been performed using statistical physics models. These models have been selected based on the adsorption isotherms profiles and applied to obtain a detailed explanation of the phenol adsorption mechanism and to understand the adsorbent performance. In particular, the phenol adsorption was analyzed using a model that assumed two layers with different adsorption energies. Modelling results, based on the number of phenol molecules adsorbed per site, suggested that two relative positions of phenol adsorbed on activated carbon surface could occur. Besides, at high temperatures, an aggregation phenomenon of phenol molecules was also hypothesized and interpreted. This adsorption process was associated to two adsorption energies that characterized the interactions between phenol – adsorbent and phenol – phenol molecules. The analysis of adsorption energies indicated that all interactions were weak resulting in a physisorption process.

Made available in DSpace on 2019-10-06T16:10:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-12-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) This paper presents an approach for impedance-based sensor monitoring of dressing tool condition in grinding by using the electromechanical impedance (EMI) technique. This method was introduced in Part 1 of this work and the purpose of this paper (Part 2) is to achieve an optimal selection of the excitation frequency band based on multi-layer neural networks (MLNN) and k-nearest neighbor classifier (k-NN). The proposed approach was validated on the basis of dressing tool condition information obtained from the monitoring of experimental dressing tests with two industrial stationary single-point dressing tools. Moreover, representative damage indices for diverse damage cases, obtained from impedance signatures at different frequency bands, were taken into account for MLNN data processing. The intelligent system was able to select the most damage-sensitive features based on optimal frequency band. The best models showed a general overall error lower than 2%, thus robustly contributing to the efficient automation of grinding and dressing operations. The promising results of this study foster the EMI-based sensor monitoring approach to fault diagnosis in dressing operations and its effective implementation for industrial grinding process automation. Faculdade de Engenharia UNESP-University Estadual Paulista Bauru Departamento de Engenharia Elétrica, Av. Eng. Luiz Edmundo C. Coube 14-01 Dipartimento di Ingegneria Chimica Università degli Studi di Napoli Federico II dei Materiali e della Produzione Industriale Faculdade de Engenharia UNESP-University Estadual Paulista Bauru Departamento de Engenharia Elétrica, Av. Eng. Luiz Edmundo C. Coube 14-01 FAPESP: 2016/02831-5 FAPESP: 2017/16921-9

© 2019 by the authors. Licensee MDPI, Basel, Switzerland.The smart management of freshwater for precision irrigation in agriculture is essential for increasing crop yield and decreasing costs, while contributing to environmental sustainability. The intense use of technologies offers a means for providing the exact amount of water needed by plants. The Internet of Things (IoT) is the natural choice for smart water management applications, even though the integration of different technologies required for making it work seamlessly in practice is still not fully accomplished. The SWAMP project develops an IoT-based smart water management platform for precision irrigation in agriculture with a hands-on approach based on four pilots in Brazil and Europe. This paper presents the SWAMP architecture, platform, and system deployments that highlight the replicability of the platform, and, as scalability is a major concern for IoT applications, it includes a performance analysis of FIWARE components used in the Platform. Results show that it is able to provide adequate performance for the SWAMP pilots, but requires specially designed configurations and the re-engineering of some components to provide higher scalability using less computational resources. 19 2 1 20 The smart management of freshwater for precision irrigation in agriculture is essential for increasing crop yield and decreasing costs, while contributing to environmental sustainability. The intense use of technologies offers a means for providing the exact amount of water needed by plants. The Internet of Things (IoT) is the natural choice for smart water management applications, even though the integration of different technologies required for making it work seamlessly in practice is still not fully accomplished. The SWAMP project develops an IoT-based smart water management platform for precision irrigation in agriculture with a hands-on approach based on four pilots in Brazil and Europe. This paper presents the SWAMP architecture, platform, and system deployments that highlight the replicability of the platform, and, as scalability is a major concern for IoT applications, it includes a performance analysis of FIWARE components used in the Platform. Results show that it is able to provide adequate performance for the SWAMP pilots, but requires specially designed configurations and the re-engineering of some components to provide higher scalability using less computational resources

This paper presents an algorithm for multi-UAV path planning in scenarios with heterogeneous Global Navigation Satellite Systems (GNSS) coverage. In these environments, cooperative strategies can be effectively exploited when flying in GNSS-challenging conditions, e.g., natural/urban canyons, while the different UAVs can fly as independent systems in the absence of navigation issues (i.e., open sky conditions). These different flight environments are taken into account at path planning level, obtaining a distributed multi-UAV system that autonomously reconfigures itself based on mission needs. Path planning, formulated as a vehicle routing problem, aims at defining smooth and flyable polynomial trajectories, whose time of flight is estimated to guarantee coexistence of different UAVs at the same challenging area. The algorithm is tested in a simulation environment directly derived from a real-world 3D scenario, for variable number of UAVs and waypoints. Its solution and computational cost are compared with optimal planning methods. Results show that the computational burden is almost unaffected by the number of UAVs, and it is compatible with near real time implementation even for a relatively large number of waypoints. The provided solution takes full advantage from the available flight resources, reducing mission time for a given set of waypoints and for increasing UAV number.

Background: Recent studies have shown that subclinical valve thrombosis in heart valve prosthesis (HVP) can be responsible for reduced leaflet motion detectable only by advanced imaging diagnostics. We conceived a novel sensorized HVP able to detect earlier any thrombus formation that may alter the leaflets motion using an electric impedance measurement, IntraValvular Impedance (IVI). Methods: For IVI measurement, dedicated electrodes are embedded in the structure of the HVP to generate a local electric field that is altered by the moving valve leaflets during their cyclic opening/closing. We present preliminary in vitro results using a first prototype of sensorized mechanical heart valve connected to an external impedance measurement system. The prototype was tested on a circulatory mock loop system and the IVI signals were recorded during both normal dynamics and experimentally induced altered working of the leaflets. Results: Recordings showed a very repetitive and stable IVI signal during the normal cyclic opening/closing of the HVP. The induced alterations in leaflet motion were reflected in the IVI signal. Conclusions: The novel sensorized HVP has great potential to give early warning of possible subclinical valve thrombosis altering the valve leaflet motion, and to help in tailoring the anticoagulation therapy.

Time domain reflectometry (TDR) is one of the most widely used techniques for indirect determination of soil volumetric water content (&theta, ). TDR measures the relative dielectric constant (&epsilon, r) which, in a three-phase system like the soil, depends on water, air, and solid matrix dielectric constants. Since dielectric constant of water is much larger than the other two, &epsilon, r of bulk soil mainly depends on water content. In many cases, the application of TDR requires a specific calibration of the relationship &theta, (&epsilon, r) to get quantitatively accurate estimates of soil water content. In fact, the relationship &theta, r) is influenced by various soil properties, such as clay content, organic matter content, bulk density, and aggregation. Numerous studies have shown that pyroclastic soils often exhibit a peculiar dielectric behavior. In Campania (Southern Italy) wide mountainous areas are covered by layered pyroclastic deposits of ashes (loamy sands) and pumices (sandy gravels), often involved in the triggering of landslides induced by rainwater infiltration. Reliable field measurements of water content of such soils are therefore important for the assessment of landslide risk. Hence, in this paper, the &theta, r) relationship has been experimentally determined on samples of typical pyroclastic soil of Campania, collected around Sarno, reconstituted with different porosities. The aim of the study is to identify specific calibration relationships for such soils based not only on empirical approaches. In this respect, a three-phase dielectric mixing model with a variable exponent is introduced, and the variable value of the exponent is related to the different dielectric properties of bond and free water within the soil pores.