Papers by Riccardo Barberi
Biosensors
In this study, polyelectrolyte (PE) layers are deposited on substrates made by glass covered with... more In this study, polyelectrolyte (PE) layers are deposited on substrates made by glass covered with an array of gold nanoparticles (GNPs). In particular, the samples studied have 0 PE layers (GGPE0), 3 PE layers (GGPE3), 11 PE layers (GGPE11), and 21 PE layers (GGPE21). All samples have been studied by micro-Raman spectroscopy. An acetic acid solution (10% v/v) has been used as a standard solution in order to investigate the SERS effect induced by different numbers of PE layers in each sample. The Surface Enhancement Raman Spectroscopy (SERS) effect correlating to the number of PE layers deposited on the samples has been shown. This effect is explained in terms of an increase in the interaction between the photon of the laser source and the plasmonic band of the GNPs due to a change of the permittivity of the surrounding medium around the GNPs. The trends of the ratios of the intensities of the Raman bands of the acetic acid solution (acetic acid and water molecules) on the band at 10...
Dottorato di Ricerca in Science and Technology of Mesophases and Molecular Materials Cycle XXI,a.... more Dottorato di Ricerca in Science and Technology of Mesophases and Molecular Materials Cycle XXI,a.a. 2007-2008University of Calabri
Nanomaterials, 2022
Induced or spontaneous chirality in natural systems is an intriguing issue. In recent years, a lo... more Induced or spontaneous chirality in natural systems is an intriguing issue. In recent years, a lot of attention has been focused on chirality of chromonic liquid crystals, a class of materials that is able to self-assemble in columnar structures. However, the mechanism involved in the arising of chirality in these materials, that starts at the molecular level and controls the supramolecular structure, is poorly understood; however, it is certainly affected by ionic strength. In this work we present the results obtained doping Cromolyn, a chromonic material, with a strong helical-twisting-power peptide, and confining it in a spherical geometry. We demonstrate, by means of optical polarized microscopy and structural analysis, that both the geometrical constraint and the presence of the chiral dopant enhance the chiral effect; we also demonstrate that they favor the rise of a highly ordered helical superstructure, that may be optimized upon adding an ionic dye to the system. Finally, w...
LaborEst, 2019
This experimental work is focused on a small solar cogeneration system of about 1 kW of electric ... more This experimental work is focused on a small solar cogeneration system of about 1 kW of electric power and up to 3 kW of thermal power, designed for the decentralised and diffuse production of heat and power with high conversion efficiencies at low power scale. The presented solar system makes use as microcogenerator of an industrial Stirling engine of small size, with an electrical efficiency up to 32%, originally designed for domestic combined heat-power applications in gas boilers. The heat acceptor of the Stirling head has been completely re-engineered for the solar application, together with a solar dish concentrator moved by a suitable two axis tracking system. In one year the average electricity produced is about 185 kWh/m2 and the average thermal energy is around 858 kWh/m2. The resulting annual electrical efficiency is about 9%, but can be improved, and the annual thermal efficiency is about 46%. The collecting surface of the solar dish measures approximately 9.6 m2, about ...
STAR is an advanced Thomson source of monochromatic and tunable, ps-long, polarised X-ray beams i... more STAR is an advanced Thomson source of monochromatic and tunable, ps-long, polarised X-ray beams in the 40-140 keV range. The commissioning has started at the U. of Calabria (Italy). The light source is driven by a high-brightness, low-emittance electron beam produced in a LINAC allowing for the source tunability and spectral density. This note reports on an emittance measurement schema based on the insertion of a slit mask in the vacuum chamber dedicated to the photocathode laser entrance. Results of the simulation of the measurement technique are reported, and the use of the data for the optimisation of the accelerator performance are detailed. The experimental setup and the application developed in EPICS for image recording and analysis are also described.
La presente invention concerne un dispositif optique a cristaux liquides a effet bistable du type... more La presente invention concerne un dispositif optique a cristaux liquides a effet bistable du type comprenant deux plaques transparentes (12, 14) pourvues d'electrodes de commande (18, 19) et entre lesquelles est place un materiau cristal liquide nematique (20), caracterise par le fait que: les plaques transparentes (12, 14) presentent un traitement de surface apte a definir deux configurations stables de molecules de materiau cristal liquide generant respectivement deux polarisations flexoelectriques ayant des composantes normales aux electrodes Pz1Pz2 de sens opposes, et il est prevu des moyens (30) aptes a appliquer au dispositif des impulsions de champ electrique perpendiculaire aux plaques (12, 14), orientees selectivement dans un sens ou dans l'autre.
Investigative Ophthalmology & Visual Science, 2010
This paper reports on the final design and the work in progress on the STAR project (IPAC2014:WEP... more This paper reports on the final design and the work in progress on the STAR project (IPAC2014:WEPRO115), which is under construction at the Univ. of Calabria (Italy). The project is devoted to the construction of an advanced Thomson source of monochromatic tunable, pslong, polarized X-ray beams, ranging from 40 up to 140 KeV. At present the buildings and main plants have been completed as the acquisition of main components: the RF photo-injector, the accelerating section, laser systems for collision and photo-cathode, RF Power Source and magnets are ready to start installation and site acceptance tests. The design of laser lines is complete and simulated by ZEMAX, aiming to minimize energy losses, optical distortions and providing a tunable experimental setup as well. The RF power network is close to be tested, it's based on a 55MW (2.5us pulse) S-band Klystron driven by a 500kV Pulse Forming Network based modulator and a Low Level RF system, running at 100 Hz. The Control Syste...
ACS Applied Materials & Interfaces, 2021
Innovative goods authentication strategies are of fundamental importance considering the increasi... more Innovative goods authentication strategies are of fundamental importance considering the increasing counterfeiting levels. Such a task has been effectively addressed with the so-called physical unclonable functions (PUFs), being physical properties of a system that characterize it univocally. PUFs are commonly implemented by exploiting naturally occurring nonidealities in clean-room fabrication processes. The broad availability of classic paradigm PUFs, however, makes them vulnerable. Here, we propose a hybrid plasmonic/photonic multilayered structure working as a three-level strong PUF. Our approach leverages on the combination of a functional nanostructured surface, a resonant response, and a unique chromatic signature all together in one single device. The structure consists of a resonant cavity, where the top mirror is replaced with a layer of plasmonic Ag nanoislands. The naturally random spatial distribution of clusters and nanoparticles formed by this deposition technique constitutes the manufacturer-resistant nanoscale morphological fingerprint of the proposed PUF. The presence of Ag nanoislands allows us to tailor the interplay between the photonic and plasmonic modes to achieve two additional security levels. The first one is constituted by the chromatic response and broad iridescence of our structures, while the second by their rich spectral response, accessible even through a common smartphone lightemitting diode. We demonstrate that the proposed architectures could also be used as an irreversible and quantitative temperature exposure label. The proposed PUFs are inexpensive, chip-to-wafer-size scalable, and can be deposited over a variety of substrates. They also hold a great promise as an encryption framework envisioning morpho-cryptography applications.
Journal of Refractive Surgery, 2005
To analyze the surface roughness of porcine corneas after excimer laser ablation with and without... more To analyze the surface roughness of porcine corneas after excimer laser ablation with and without the smoothing procedure by means of atomic force microscopy. Excimer laser photorefractive keratectomy (PRK) was performed on eight porcine corneas. Immediately following the procedure, smoothing was performed on four corneas using a viscous solution of 0.25% sodium hyaluronate. The corneas were examined in balanced salt solution after fixation in 2.5% glutaraldehyde solution using atomic force microscopy. Quantitative analysis of the ablated stromal surface topography was performed using the section analysis module of the atomic force microscopy software. Repeated measurements were made over small areas (< or =50 microm2) near the center of each ablation, with a vertical resolution of <1 nm. Images of the ablated stromal surface showed undulations and granule-like features on the ablated surface of the specimens. The specimens on which the smoothing procedure was performed (root-mean-square [RMS] rough: 0.152 +/- 0.014 microm) were more regular (P < .001) than those on which PRK alone was performed (RMS rough: 0.229 +/- 0.018 microm). Atomic force microscopy analysis requires a simpler preparation of the specimens with respect to that necessary for scanning electron microscopy; for this reason, atomic force microscopy techniques are more reliable for the study of biological surfaces and prove to be a feasible method to establish the differences when comparing different laser techniques. Our investigations highlight that although the laser cut of scanning-spot excimer laser systems is precise in removing even the smallest amounts of tissue, the smoothing technique may still be useful to reduce post-ablation roughness.
Fusion Engineering and Design, 2019
The Southern Europe Thomson Backscattering Source for Applied Research (STAR) is a compact hard X... more The Southern Europe Thomson Backscattering Source for Applied Research (STAR) is a compact hard Xray source designed by INFN, for advanced applied materials-science research. It is funded by Progetto MaTeRiA, a partnership between the University of Calabria and CNISM (Consorzio Nazionale Interuniversitario per le Scienze fisiche della Materia). The machine has been installed at the University of Calabria (UNICAL); the X-ray beam is produced using the Thomson Back-scattering process, where relativistic electron bunches, accelerated by a 60 MeV Linear Accelerator (LINAC), interact with very short photon pulses, produced a by a 30 mJ@5 ps IR (Infrared) Pulsed Laser. The EPICS-based command/control system (ComConS) of the STAR machine has been designed and currently is under commissioning, using state of the art technologies and making extensive use of COTS hardware and software, assuring full control and supervision of the whole machine and all relevant subsystems: Beam diagnostics, Magnets power supplies, RF devices, Laser systems, Vacuum subsystem, Machine Protection System, Personnel Protection System and Trigger and Timing system. A growth potential has been considered since design phase, in order to take into account any future expansions of the control system during the lifecycle of the facility, without impact on the performance. Scalability of systems is also a crucial issue. The current design allows to generate tunable collimated monochromatic X-rays in the range between 10 and 200 keV. Possible future evolution will be to obtain a machine to generate higher energy X-ray beams, towards the MeV. The control system from both SW and HW points of view has to accommodate this need, as well as operating the machine for a long lifecycle.
Cells, 2018
Vesicle fusion is a fundamental cell biological process similar from yeasts to humans. For secret... more Vesicle fusion is a fundamental cell biological process similar from yeasts to humans. For secretory vesicles, swelling is considered a step required for the expulsion of intravesicular content. Here this concept is revisited providing evidence that it may instead represent a general mechanism. We report the first example that non-secretory vesicles, committed to insert the Aquaporin-2 water channel into the plasma membrane, swell and this phenomenon is required for fusion to plasma membrane. Through an interdisciplinary approach, using atomic force microscope (AFM), a fluorescence-based assay of vesicle volume changes and NMR spectroscopy to measure water self-diffusion coefficient, we provide evidence that Gi protein modulation of potassium channel TASK-2 localized in AQP2 vesicles, is required for vesicle swelling. Estimated intravesicular K+ concentration in AQP2 vesicles, as measured by inductively coupled plasma mass spectrometry, was 5.3 mM, demonstrating the existence of an ...
Optical Materials Express, 2018
With the rapid development of modern information technology, massive amounts of data are stored t... more With the rapid development of modern information technology, massive amounts of data are stored that require an information security. Here, we introduce a spiropyran doped polymer dispersed cholesteric liquid crystal film based rewritable medium that can produce high quality visual two-dimensional barcodes for anti-counterfeiting, authentication and security purposes. The prepared film exhibits excellent photochromic properties, improved photosensitivity, high spatial resolution, and numerous rapid write/erase capabilities. Such rewritable material can be efficiently printed over 70 cycles without compromising its readability. Furthermore, the fabricated film is mechanically resistant to small stresses and, hence, it can be directly handled.
Beilstein journal of nanotechnology, 2018
In the last decade, much interest has grown around the possibility to use liquid-crystal droplets... more In the last decade, much interest has grown around the possibility to use liquid-crystal droplets as optical microcavities and lasers. In particular, 3D laser emission from dye-doped cholesteric liquid crystals confined inside microdroplets paves the way for many applications in the field of sensors or tunable photonics. Several techniques can be used to obtain small microresonators as, for example, dispersing a liquid crystal inside an immiscible isotropic fluid to create an emulsion. Recently, the possibility to obtain a thin free-standing film starting from an emulsion having a mixture of water and polyvinyl alcohol as isotropic matrix has been reported. After the water evaporation, a polymeric film in which the microdroplets are encapsulated has been obtained. Bragg-type laser emission has been recorded from the emulsion as well as from the thin film. Here, we report on the possibility to tune the laser emission as a function of temperature. Using a chiral dopant with temperatur...
Journal de Physique II, 1995
Sensors and Actuators B: Chemical, 2017
The method relies on the laser emission from a cuvette containing a pH sensitive dye stimulated... more The method relies on the laser emission from a cuvette containing a pH sensitive dye stimulated by the irradiation with a pumping beam. The emitted laser wavelength shifts as a function of the acid molecules presence. From the emitted wavelength the amount of acid can be precisely determined. This work presents a laser spectroscopy based method to detect very small amounts of acidic molecules in concentrations down to 10 ppm. The proposed method relies on the sensitivity to acids of a fluorescent dye, which is used as the active material in a stimulated laser emission experiment. Using a cuvette, that works as a resonator, laser emission from a dye doped mixture can be observed. When an acidic species is added to the mixture, due to the solvatochromic effect, the spectral position of fluorescence shifts and, consequently, a shift in the emitted laser wavelength is observed. From the analysis of the laser lines the presence of a specific acid species and its concentration can be determined.
Soft matter, Jan 14, 2017
Microdroplet systems have attracted great interest because of their wide range of applications, e... more Microdroplet systems have attracted great interest because of their wide range of applications, easiness in processing and handling, feasibility in developing miniaturized devices with high performances and large flexibility. In this study, a stable emulsion based on different dye-doped chiral liquid crystal droplets has been engineered in order to achieve simultaneous omnidirectional lasing at different wavelengths. To obtain the mixed emulsion of dye doped Bragg onion-type microresonators the twofold action, as a surfactant and a droplet stabilizer, of the polyvinyl alcohol dissolved in water has been exploited. Multiple wavelengths lasing in all directions around the mixed emulsion is demonstrated. By water evaporation, a plastic sheet including different types of chiral droplets is also obtained, retaining all the emission characteristic of the precursor emulsion. A relevant feature is the large flexibility of the preparation method that enables an easy and full control of the l...
Sensors, 2016
The gold nanoparticle (GNP) aggregation growth induced by deoxyribonucleic acid (DNA) is studied ... more The gold nanoparticle (GNP) aggregation growth induced by deoxyribonucleic acid (DNA) is studied by laser scanning confocal and environmental scanning electron microscopies. As in the investigated case the direct light scattering analysis is not suitable, we observe the behavior of the fluorescence produced by a dye and we detect the aggregation by the shift and the broadening of the fluorescence peak. Results of laser scanning confocal microscopy images and the fluorescence emission spectra from lambda scan mode suggest, in fact, that the intruding of the hydrophobic moiety of the probe within the cationic surfactants bilayer film coating GNPs results in a Förster resonance energy transfer. The environmental scanning electron microscopy images show that DNA molecules act as template to assemble GNPs into three-dimensional structures which are reminiscent of the DNA helix. This study is useful to design better nanobiotechnological devices using GNPs and DNA.
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Papers by Riccardo Barberi