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Measurements of the carbon dioxide (CO2) diffusion in graphene oxide (GO) and reduced graphene oxide (rGO) vs. temperature have been performed using uniform GO thin foils with15 mu m thickness. Regarding rGO, its foils have been obtained by submitting GO at a temperature of 130 degrees C in vacuum for 30 min. The CO2 diffusion has been controlled by the gas pressure gradient applied to two faces of the thin foils versus the time and the temperature. The calculated CO2 coefficient diffusions have been compared with those relative to the nitrogen (N-2) and argon (Ar) gases obtained in previous measurements. The deduced diffusion coefficients are different for the three investigated gases, but remain of the order of 10(-3) cm(2)/s. At room temperature in GO the minimum value is obtained for nitrogen, while the highest one for Ar. Indeed, at 100 degrees C in rGO the minimum value is deduced for nitrogen and the maximum one for the carbon dioxide. The different diffusion coefficients can be attributed not only to the different size, shape and atomic mass of the investigated gases, but also to the inner lattice structure of the GO and rGO foils. GO contains water and oxygen functional groups which obstacle the diffusion process. rGO is poorer of oxygen functional groups and of water, partially enhancing the diffusion, but it has a high compactness and density which may reduce the total diffusivity. The obtained results, their correlation with the inner structure of the graphene sheets and the comparison between measurements and the literature data are presented and discussed.

A compressible capacitive mechanical pressure sensor has been developed. Porous polydimethylsiloxane (p-PDMS) has been chosen as dielectric insulator because of its dielectric constant value. Gold nanoparticles have been embedded in p-PDMS to change the dielectric properties and to tune its elasticity. p-PDMS and its nanocomposite have been synthesized using the sugar leaching process. The p-PDMS physical characterization, with and without the gold nanoparticles, has been conducted to investigate its elastic response to compressive stresses as a function of both the polymer preparation thermal treatment and the gold nanoparticle concentration. A sensor operating in a low-pressure range between about 100 Pa and 10 kPa with a strain ranging between about 5% and 95% has been realized. Dielectric constant and electrical resistivity measurements have been performed using samples with a starting volume of the order of 1 cm3. The relationship between the dielectric constant, the electrical resistivity and the compressive stress/strain has been also deduced. The described sensor is flexible, biocompatible, water equivalent and can have applications in biomedicine (orthopedic, dentistry), engineering (stress–strain measurements, robotics), and microelectronics (microbalances, stress test on electronic devices).

The INFN-CIMA project deals with the employment of graphene, graphene oxide (GO) and reduced graphene oxide (rGO) for applications in Nuclear Physics. In particular, the project aim is that to use ...

This paper presents some experimental results about the 7Li, 11B and 19F (p, α) nuclear reactions developed using proton beams at energy below 3 MeV in order to be applied to protontherapy. The energy released by proton beams during radiotherapy acts mainly at the end of the proton path in the biological medium, where it increases at high density inside the tumor. At this depth, it is possible to inject in the tumor compounds containing Li, B and F to generate energetic alpha particles from nuclear reactions. At the proton Bragg peak position it is possible to produce 1–8 MeV alpha particles, which enhance the energy density deposited in the tumor increasing the probability to damage the cells. Thanks to the higher relative biological efficiency of the alpha particles with respect to protons, it is expected that the alpha synergic particles defeat the tumor at lower doses.

2.0 MeV proton beam accelerated at Tandetron is extracted in air through a thin film and allowed to scatter to irradiate the cell culture attached to the polymeric base of a biological flask. The irradiated cells were human medulloblastoma cell line Daoy treated with and without 5 nm sized spherical gold nanoparticles. Proton doses from 0.5 to 1.5 Gy have been employed to irradiate the cultures and to investigate the role of the radiotherapy performed with and without the use of the gold nanoparticles. Results indicated that cell survival is significantly reduced to about 50% when the nanoparticles at a concentration of about 6 × 1013 particles/ml are employed.

Reduced graphene oxide (rGO) is a two-dimensional material, which is attracting increasing attention due to its special properties. It can be obtained by laser or ion beam irradiations of pristine ...

The possible precipitation or dispersion of Au was followed in non-polar ZnO (10-10) implanted with Au+ 1 MeV ions at the ion fluence 1.5 × 1016 cm−2 and subsequent annealing at 600 °C for 1 h in ambient atmosphere. Afterward irradiation using O3+ 10 MeV ions with fluence 5 × 1014 cm−2 was used to modify Au distribution and internal morphology as well as the structure modification of ZnO host matrix. Rutherford Backscattering Spectrometry (RBS) in channelling mode (RBS-C) and Raman spectroscopy show that the subsequent O irradiation with high electronic energy transfer slightly decreased Zn sub-lattice disorder in m-plane ZnO and increased significantly O sub-lattice disorder. Optical absorbance in the wavelengths ranging from 350 to 700 nm shows the increasing absorbance mainly between 450 and 500 nm and progressive shift of absorbance edge to the higher wavelengths after Au implantation and oxygen irradiation. The distinct absorbance curves appeared in the case where polarized light were used at angles 0° and 90° in oxygen irradiated ZnO:Au samples indicating Au dispersion modification. Transmission Electron Microscopy (TEM) with Energy Dispersive Spectroscopy (EDS) observed Au cluster morphology and an elemental composition showing Au rich clusters of the sizes 10–20 nm in the as-implanted and as-annealed samples containing probably ZnO nanocrystallites.

Electrical measurements on a graphene field effect transistor (GFET) are presented and discussed for its characterization in vacuum and in air. In this last environment three low output power continuous wave (CW) led lasers and a UV lamp have been used to study the illumination effects at wavelengths from the near infrared (NIR) to red, green up to near UV. In air the device is sensitive to visible and UV radiation. The visible light produces charge carriers increasing the source-drain current. Instead, the UV radiation induces the graphene oxidation decreasing the source-drain current in a permanent way. Small temperature increments, up to about 55∘C, increase the electrical conduction. Larger temperatures and prolonged heating in air generate oxidation, decreasing the source-drain current. As far as the NIR radiation is concerned, no effect is observed. Therefore, these preliminary investigations indicate that the device can be employed as visible and UV radiation detector.

Ion irradiation reduces oxidized graphene but causes morphological and structural changes in individual sheets. Graphene oxide (GO) films were irradiated under vacuum with ion beams having different atomic numbers and energies in the range (2–16) MeV. The structural and morphological changes undergone by the individual sheets of reduced graphene oxide (rGO) were analyzed by transmission electron microscopy and Raman spectroscopy. In particular, the electron diffraction highlights the deformations of the sheets through the deformation of the diffraction spots. A quantitative structural evaluation of such features was carried out using a new method based on the analysis of the radial and azimuth profiles extracted from the electron diffraction pattern. The spots deformation involves both the direction normal to the reciprocal lattice vectors and the parallel one. The former deformation is related to the non-planarity of the surface, the latter to the rearrangement of the deformed lattice. Experimental evidence indicates that there are many different orientations present within the electron beam with a diameter of less than one micron and that the surface normal of the sheet must vary in all directions. This is the result of a microscopic roughness inside the sheets. The progressive deformation of the spots depends on the absorbed ion dose. The morphological analysis, carried out at high resolution on rGO sheets, confirms structural results: the rGO sheets take on a static not flat but rippled configuration. Accentuated ripples are dose dependent.

At present graphene is the most exciting star in the materials science but graphene oxide, GO, that is its low-cost precursor attracts researchers from various fields because it is very easily produced at low cost. GO is an electrical insulator than can be transformed into graphene through the 'reduction' process. The oxygen functional groups it contains can be removed by various ways, also using lasers, ion beams and the intercalation process. The intensive research on graphene has allowed the rediscovery of various graphite-like layered materials with composition other than carbon, but properties are not yet fully known and with interesting possible applications. Among them, manganese thiophosphate, MnPS3, is a layered inorganic host matrix for making, through the intercalation-exfoliation-restacking technique, multi-functional hybrid thin films that can find application as optical switches, transparent coatings, in catalysis and photocatalysis, as lubricants, to create new multilayer structures, as dielectric substrates for graphene-based electronics and so on. If exfoliated at few layers, MnPS3 allows to realize good ultraviolet photodetectors with a gate tunable photoresponsivity and high photo gain. Recent progress in these graphene-like materials will be presented and discussed together with measurements based on the use of lasers, ion beams and intercalation emphasizing their potential applications.

Light trapping and luminescence have been observed in polydimethylsiloxane (PDMS) foils containing about 0.1-0.2 wt% gold nanoparticles (AuNPs). The so-prepared PDMSs have been physically characterized using SEM microscopy, UV-Vis, FTIR and Raman spectroscopies. The used AuNPs have been controlled by means of the surface plasmon resonance absorption spectra. In the AuNPs-PDMS foils, a luminescence peak at about 425 nm has been induced by an exciting light at 280 nm. The light injection with an optical fiber is trapped inside the polymer-containing NPs and illuminates all the polymer volume. The measurements of scattered light show an increment in the light intensity due to the presence of AuNPs and air bubbles inducing diffractions, reflections and Mie scattering. Further investigations have been conducted irradiating the PDMS with AuNPs in vacuum with 2.9 MeV proton beams producing luminescence in the blue region. The mechanisms of light trapping and luminescence and the possible applications of the prepared material are presented and discussed.

mu Raman spectra of graphene oxide (GO) and reduced graphene oxide (rGO) foils, subjected to 2 divided by 3 MeV proton beam irradiations in vacuum at low and high fluence, have been investigated. The spectra detailed analysis indicates that the characteristic D and G peaks yields ratio, the area of the D" peak, located between D and G, the G peak full width at half maximum, the C-H band area and full width at half maximum are functions of the absorbed dose. The D and the D" peaks presence is indicative of the disorder generated in the target by the ion beam. All these observations suggest some useful indexes to read the proton absorbed dose by the irradiated rGO foils. Therefore, these GO based foils can be employed as dosimeters for proton beams in a large range of absorbed dose, from about 100 Gy up to about 114 MGy, within which Raman signals respond linearly.

Graphene-based materials have peculiar optical, electrical, mechanical and chemical properties, which make them useful for making thin films and thick sheets suitable for different needs. Matter physics, nuclear physics, microelectronics, biomedicine, engineering, agriculture and cultural heritage just represent some of the sectors in which these materials can be successfully used. The advancements allow us to go from a given graphene-based material to another transforming, for example, the insulator graphene oxide to electrically and thermally conductive reduced graphene oxide. Thanks to the interesting properties possessed by graphene-based materials, it is possible to realize gas sensors, dosimeters for ionizing radiation, light detectors, electronic devices, membranes for gases and desalination, biocompatible surfaces, medical protheses and thin coating films to preserve underlying layers. Different analysis techniques are presented to control the physical modifications of reduced graphene oxide (rGO) due to the different treatments for the pristine one. The paper reports the possibility to realize GO micro-dosimeters for ionizing radiations, sensors for air humidity and other gases, field effect transistors as the detector of visible and UV radiations, GO and rGO membranes realization for different gases, source ion strippers to enhance the charge state of different ions to be accelerated. Some of these aspects and possible applications will be presented and discussed with measurements carried out in our laboratories.

The polydimethylsiloxane (PDMS) luminescence, induced by MeV proton beams, has been investigated in the pure and doped polymer. Gold nanoparticles (AuNPs) and graphene oxide microparticles (GOμPs) have been employed at low concentration (0.1 wt%) to modify the PDMS properties. Measurements have demonstrated that AuNPs enhance the PDMS luminescence, while GOμPs quench the polymer luminescence. The first ones, embedded into PDMS, produce a visible luminescence whose intensity is proportional to the absorbed proton dose. A linearity between the luminescence intensity and the proton absorbed dose is observed up to about 2.5 kGy, while at higher doses a luminescence saturation region shows up. The polymer can be employed to monitor in vacuum the proton beam spot size and shape and as a plastic scintillator dosimeter with peculiar elastic properties and high biocompatibility, as it will be presented and discussed.

Gafchromic HD-V2 films are employed to study the response to light ions useful in radiotherapy, such as protons, helium and carbon beams. The effects induced by the ions at an energy within about 300 keV and 16 MeV were investigated in terms of optical absorbance measurements in the irradiated active region of the film. The employed ion doses range between 0.4 Gy and 12 kGy. The results show that the net optical density increases almost exponentially with the absorbed dose and that it becomes saturated after prolonged dose higher than 1 kGy. The optical density produced in the film was measured by light transmission measurements at 700 nm wavelength, at which is observed the highest gafchromic sensitivity. Calibration curves of optical density versus exposure dose and type of ion are given. The dependence on the ion stopping power was presented and discussed.

The graphene oxide (GO) reduction by ionizing radiation is proportional to the absorbed dose due to the energy release which produces ionizations, deexcitations, chemical bonding breaking, radical formation and recombination, oxygen functional groups and water desorption. Thanks to this, GO can be employed as a dosimeter whose dose can be measured using different analysis techniques, such as Raman spectroscopy, X-ray diffraction (XRD) and Energy Dispersive X-ray (EDX) analysis based on the characteristic X-ray emission, X-ray photoelectron spectroscopy (XPS). To evaluate the GO reduction as a function of the Linear Energy Transfer (LET) of the used radiation, measurements have been performed with XPS and EDX to deduce the C/O atomic ratio versus the X-rays, electron and ion beam energy loss. Results indicate that a linear dependence on LET occurs, as will be presented and discussed.

Proton acceleration can be induced by non-equilibrium plasma developed by high-intensity laser pulses, at 1016 W/cm2, irradiating different types of thin polyethylene targets. The process of proton acceleration and directive yield emission was investigated, optimizing the laser parameters, the irradiation conditions, and the target properties. The use of 600 J pulse energy, a laser focalization inducing self-focusing effects and advanced targets with embedded nanoparticles and optimal thicknesses, has permitted to accelerate forward protons up to the energies of about 6 MeV and amount of the order of 1015 H+/pulse. High proton energy is obtained using thin foils enriched with gold nanoparticles, whereas high proton yield is obtained using targets with a thickness of about 10 μm. The plasma diagnostics using SiC semiconductor detectors in time-of-flight configuration was fundamental to monitor the optimal conditions to improve the plasma processes concerning the ion acceleration and the X-ray and relativistic electron emission.

A Nd:YAG laser operating at 1064 nm was used to irradiate, at different intensities, graphene oxide foils placed in vacuum and in air. The laser irradiated GO foils were analysed successively by using different techniques such as 2.0 MeV alpha particle Rutherford backscattering spectrometry, X-ray photoemission spectroscopy and SEM-EDX. In particular, in vacuum irradiated graphene oxide samples the oxygen reduction has been observed with increment of the carbon content. In air irradiated GO samples an increase in oxygen has instead been highlighted. Furthermore thermal and chemical effects are induced by the photon irradiation. Results will be presented and discussed.

An efficient mask-less production of patterns in insulating foils of graphene-oxide was carried out under impact of 5 MeV alpha particle beams delivered by the Ion Micro Beam system at the Tandetron Laboratory of the Nuclear Physics Institute in Rez (Czech Republic). Graphene-oxide (GO) matrix has been exposed to controlled fluences with the aim of inducing deoxygenation and enhancement of the electrical conductivity in selected areas of the exposed samples. The reported designed patterns and their sharp edge profiles demonstrate the feasibility of the process. The compositional changes in the exposed areas of the GO were investigated by Rutherford backscattering spectrometry, elastic recoil detection analysis, scanning electron microscopy, and correlated with the electrical properties measured by a standard 2-point probe technique.

The Nuclear Physics Institute (NPI) of the Czech Academy of Sciences (CAS) operates, among other facilities, a Tandetron linear accelerator, TR-24 and U-120M cyclotrons, and an MT25 microtron. A new accelerator mass spectrometry (AMS) instrument, MILEA, has recently been acquired. Except for the MT25, all facilities are synergic parts of the Centre of Accelerators and Nuclear Analytical Methods Research Infrastructure (CANAM RI) ( http://canam.ujf.cas.cz ). This paper demonstrates the instrumental, scientific and application capabilities of the devices for many fundamental nuclear physics experiments and a wide spectrum of applications. The Tandetron Laboratory has a full arsenal of ion-beam analytical methods, ion-beam nano- and microstructuring techniques, as well as tools for the doping and synthesis of new progressive materials using energetic ion beams. It uniquely utilises ion beams for 3D elemental mapping; it studies internal morphology using ion-microprobe methods applicable in many scientific branches. The TR-24 and U-120M cyclotrons provide the primary beams of accelerated ions as well as the generated secondary fast neutrons, including the necessary instrumentation and the target technology, and enable fundamental experiments in nuclear physics, astrophysics, dosimetry, etc. The microtron MT25 is a source of relativistic electrons (the primary electron beam), the secondary photon beam (bremsstrahlung) and neutrons from photonuclear reactions which are used, e.g. for analysis and preservation of cultural heritage. The MILEA AMS system offers a highly sensitive isotopic ratio measurement of very long-lived radionuclides at levels up to 10–15.

Different ion beams, from protons up to gold ions, with energy from 2 MeV up to 16 MeV, have been employed to irradiate graphene oxide (GO) foils in vacuum. The ion energy deposition reduces GO releasing functional oxygen groups. The effect of radiating ions – GO foils interaction has been investigated by Raman spectroscopy, X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). All the performed analyses show that both reduction and damaging depend on the fluence, the energy and the type of radiating ions. In the regime of electron stopping power the reduction is linearly dependent on the absorbed dose, while in the regime of nuclear stopping power an intense damage is produced in GO, altering the Raman spectrum and producing defects and amorphization of the material. The achieved goal was to quantify the GO's response to ionizing radiation with the aim of using the GO foil as a dosimeter for high energy ion beams.

In this paper, the synthesis of macro-porous polydimethylsiloxane (PDMS) sponges decorated with reduced graphene oxide and graphene is described using a top-down approach based on the sugar templating process. Among the multiple assets enjoyed by PDMS, its elasticity and porosity make possible the uniform dispersion of embedded graphene-based material into its structure. Where possible, the optical, surface and morphology properties of both porous PDMS composites and their not porous (bulk) counterparts have been studied. Scanning transmission ion microscopy (STIM), based on the reciprocity between the beam energy loss and the sample areal density, has been used to obtain the images of the sponge internal part. A detailed spatial resolution of the PDMS microstructure has been deduced by the areal density map. The homogeneous dispersion of the fillers was observed by scanning electron microscopy (SEM) and indirectly by light transmittance measures performed in several regions of the PDMS bulk. The reduced graphene oxide and graphene introduced into PDMS significantly improve its electrical conductivity. The porosity of the presented hybrid material holds a key role for good performances in microelectronics and biomedicine.

Measurements of nitrogen diffusion coefficient in graphene oxide (GO) and reduced graphene oxide (rGO) have been performed at different temperatures ranging between 21 °C and 101 °C. GO and rGO foils have been prepared as thin foils with 15 μm in thickness, total surface of about 5 cm2 and active diffusion surface of about 20 mm2. The rGO foils have been obtained by thermal annealing at 170 °C for 30 min in air. The measured room temperature diffusion coefficients, of 3.43 × 10−4 cm2/s for GO and 5.1 × 10−4 cm2/s for rGO, and, at 101 °C, of 5.22 × 10−4 cm2/s for GO and 10.7 × 10−4 cm2/s for rGO, have been obtained with a simple experimental set-up measuring the gas pressure gradient applied to the two faces of the thin foils versus the time. The rGO foils show a significant increasing of the diffusion coefficients with respect to the pristine GO due to the removing of water and some functional oxygen groups which determines the aperture of nanochannels through which the N2 gas diffuses. The thermal activation energy of nitrogen diffusion is evaluated for the two investigated materials. The experimental apparatus to measure the diffusion coefficients, the obtained results, their correlation with the graphene sheets structure and the comparison with the literature data are presented and discussed.

Different ion beams, with energy from 2 MeV up to 16 MeV at different atomic number, have been employed to irradiate graphene oxide (GO) foils in vacuum. Due to effects of electron and nuclear ion stopping powers, the ion energy deposition reduces the irradiated GO foils and structurally modifies them. The ion bombarded GO foils X-ray diffraction (XRD) investigations have permitted to shed light on the different structural phases induced by the ion energy deposition. The changes in the GO foils pristine structure shift the diffraction main peak towards larger angles and produce new diffraction peaks indicating the presence of new phases, such as reduced GO (rGO), carbon nanotubes (CNT), amorphous carbon (a-C), onion like carbon (OLC) and probably new carbon allotropes. The obtained results indicate that the inner structure of the GO foils becomes more and more compact and dense with the absorbed dose, suggesting that the removal of the functional oxygen groups leads to a near graphite structure with a significant increase of the material mass density. The different structural phase modifications induced by the different ion beams as a function of the stopping power, fluence and dose will be presented and discussed in detail.

Noble metal nanoparticles dispersed in semiconductors, mainly in ZnO, have been intensively investigated. Au dispersion and possible precipitation as well as damage growth were studied in ZnO of various orientations, a-plane (110) and c-plane (0001), using 1 MeV Au+-ion implantation with an ion fluence of 1.5 × 1016 cm−2 and subsequently annealed at 600 °C in an ambient atmosphere for one hour. Afterwards, irradiation with 10 MeV O3+ at a fluence of 5 × 1014 cm−2 was used to modify Au distribution and internal morphology as well as to follow the structural modification of ZnO under high-energy light-ion irradiation. Rutherford backscattering spectrometry in the channelling mode (RBS-C) and Raman spectroscopy show that O irradiation with high electronic energy transfer distinctly modifies the implanted Au layer in various ZnO facets; it introduces additional displacement and disorder in the O sublattice mainly in the a-plane while not creating an additional strain in this facet. This has been confirmed by XRD analysis, identifying the appearance of an additional phase (nanocrystallites) after Au implantation, which diminishes after O irradiation, and RBS-C has identified decreased disorder in the Zn-sublattice. Unlike in c-plane ZnO, it has been possible to observe a local compressive deformation around spherical defects, which is more pronounced after O irradiation simultaneously with the vertical strain introduced in the Au-implanted and annealed layer. Transmission electron microscopy (TEM) with energy dispersive spectroscopy (EDS) was employed to investigate the interior morphology, showing the occurrence of Au-hcp clusters of the small sizes of about 4–10 nm; neither the cluster sizes nor their shapes are significantly affected by the O irradiation.

Radiochromic films (RCF), also called GafChromic™ films, represent a performant material for accurate quantitative radiation dosimetry. Their compositions allow high dose sensitivity and fewer envi...

A pulsed ns IR laser at about 1010 W/cm2 intensity is employed to irradiate a Cu target placed in a vacuum and in nitrogen gas. The produced plasma is characterized in terms of emitted ions and photons as a function of the nitrogen pressure in the chamber. The mechanisms of ion gas interactions are investigated in terms of Cu ion energy loss and X-ray attenuation using an ion collector and a SiC detector. A fast CCD camera in the visible region has produced the collision images of the ions with the nitrogen molecules. A plasma temperature of about 44 eV, an emission of soft X-rays up to about 100 eV, an ablation yield of about 2.4 × 1015 atoms/pulse, a maximum Cu ion acceleration of 1.4 keV and a maximum ionization up to Cu9+ were measured in high vacuum.

The preparation of spherical metallic nanoparticles (NPs), in the range of 10-100 nm, using pulsed laser ablation in water has particular interest in many scientific fields. The fast released laser energy to the solid metal in water produces plasma at the solid-liquid interface generating NPs in solution. The size distribution and the solution concentration depend by many parameters concerning the laser source (wavelength, pulse energy, pulse duration), the irradiation conditions (target depth in water, focal spot, repetition rate, irradiation time), and the medium where the ablation occurs (water, solution concentration, presence of surfactants). Optimal conditions can be found to control the average particle size, the size distribution, and the coalescence effect. A study of the NPs dependence from the ns pulsed Nd:YAG laser, irradiating metals in water is presented, discussing also the physical characterization of the produced NPs employing microscopy and optical analyses.

A simple, cost-effective approach to realize a sensitive temperature sensor based on IR laser reduced graphene oxide (IRLrGO) is reported. The sensor has been obtained by irradiating a graphene oxide (GO) film, placed between two thin glass substrates, with a continuous wave diode laser operating at 970 nm along its entire length. A conductive strip, 13 mm long, 300 μm wide and 7 μm thick, has been generated by moving the GO film on an X-Y translator stage with a given velocity with respect to the fixed laser fiber tip position. The laser treatment has given rise to the GO reduction confirmed by the resistance R measurements as well as from SEM, EDX, ATR-FTIR and Raman analyses. The temperature dependence of the conductive strip resistance has been measured in air from 30ˆC to 80ˆC and in high vacuum from 80 K to 300 K. The sample acts as a sensitive and low mass Resistance Temperature Detector (RTD). Such a sensor is biocompatible and requires a very low bias (

Thin foils of graphene oxide (GO) are irradiated by a fs titanium sapphire laser at an intensity of about 1019 W/cm2 in high vacuum. The produced plasma in the forward direction accelerates ions in a regime of target-normal-sheath-acceleration, thanks to the relativistic electron emission from the target surface and to their emission from the rear foil surface, generating a high electric field pulse with the positive target. The ion acceleration is measured mainly using SiC detectors in the time-of-flight configuration. Adding gold as nanoparticles or as a thin coverage film, the ion acceleration is enhanced as a result of a higher plasma electron density. The optimal acceleration is reached by varying the GO thickness, the Au nanoparticle concentration, the thin Au film thickness, and the irradiation conditions. Particularly important is the laser focal position with respect to the target surface, which is responsible for different acceleration values. In the used experimental conditions, a maximum proton energy of 2.6 MeV was obtained and the best modality to add Au atoms to the target is discussed.

Graphene oxide (GO) micrometric foils have been prepared using a graphene oxide solution. A pulsed IR laser at 970 nm wavelength, with a 100 ms pulse duration and an energy between 50 mJ and 0.7 J, has been employed to irradiate the micrometric GO foils in air. Pulsed IR laser irradiation of GO foils promotes the GO reduction in air and, when the GO foils are tightened between two transparent and thin flat glasses, it permits to realize electrically conductive strips, labelled as rGO. Measurements of laser ablation yield in air as a function of the pulse energy, analysis of elemental composition of the samples before and after the irradiation and morphological characterization have been performed. An estimation of both the temperature induced by the laser treatment and the penetration depth is presented. The so-obtained rGO foils can find many interesting applications in microelectronics, engineering and bio-medicine as sensors, detectors, ion strippers and dosimeters.

A new type of ion dosimeter based on graphene oxide (GO) foils is presented and discussed. GO is biocompatible, stable, tissue equivalent and has special chemical and physical properties. The ion i...

A hybrid material incorporating gold nanoparticles (Au-NPs) in polydimethylsiloxane (PDMS) has been synthesized. Gold nanoparticles gained wide interest for their optical, chemical and physical properties, such as surface plasmon oscillations resonant absorption, chemical structure, imaging and sensing. Au-NPs can be conjugated with several functionalizing agents, such as polymeric chains, improving their properties and performances. PDMS composites with weight percentages ranging between 0.1 and 0.2% of spherical Au-NPs (10 nm diameter), were produced. In this work, we report on different dispersion effects of gold nanoparticles in PDMS. The surface morphology was investigated by atomic force microscopy (AFM) and wetting ability analyses. The presence of structures inside both virgin and hybrid PDMS containing Au-NPs was preliminary investigated by Small Angle X-ray Scattering (SAXS). The optical performance of such hybrid material was studied by UV-VIS spectroscopy, in transmission mode. An enhancement of the absorption was reported as a function of increasing percentage of gold nanoparticles and changing the nanoparticles dispersion approach. The presented hybrid material could be promising for many useful applications, such as optical waveguides, sensors and switches in optoelectronics.

The oxygen content in graphene oxide (GO) can be reduced by the ion beam irradiation in high vacuum conditions. The reduction changes the C/O atomic ratio that increases with the absorbed ion dose. Moreover, as the level of reduction increases, the surface flattens and the material becomes denser. At high absorbed doses, greater than about 100 MGy, the material is affected by the high energy deposited with damage radiation effects which make the C/O ratio not proportional to the dose. At low doses, less than about 100 MGy, the C/O atomic ratio shows an optimal linearity with the ion dose and is independent of the ion stopping power, thus assuming the characteristics of a good biocompatible water-tissue equivalent dosimeter. The aim of the work was that to explore the possibility to use GO as ionizing radiation dosimeter for energetic ion beams by the measure of the compositional C/O atomic ratio.

Background: Antipsychotic drugs (APs) are increasingly used to treat a variety of psychiatric disorders in children and adolescents. However, their safety and tolerability profiles, when used in a developmental age context, show different characteristics from the ones observed in adult patients. Treatment with APs in pediatric patients is often long-term. However, the tolerability data regarding these patients mostly derive from short-term studies.Methods: Starting from April 2017, for a 1-year period, patients between 4 and 18 years of age followed by five units of developmental age neuropsychiatry, who initiated a treatment with at least an AP (ATC class N05A) were included into the study. Patient-related data have been collected at baseline and regularly thereafter, as allowed by the clinical routine. Changes to continuous variables over time have been analyzed using a linear mixed model in subsamples of our population treated with risperidone or aripiprazole.Results: During the observation period, 158 patients were initially enrolled, but only 116 completed 12 months of therapy with an AP. Risperidone was the most used AP (n = 52) followed by aripiprazole (n = 44) and olanzapine (n = 7). For both the aripiprazole and risperidone groups, the mean body mass index (BMI) (P < 0.001 for both groups) and heart rate (P = 0.026 for aripiprazole group and P < 0.001 for the risperidone one) values significantly increased over time. The mean prolactin concentration value significantly increased over time only in the risperidone group (P = 0.04). Eighty-six patients experienced at least one adverse drug reaction (ADR), accounting for a total of 238 specific reactions, with the most frequent being weight gain (n = 34), increased serum prolactin levels (n = 21), hyperphagia (n = 20), and hypercholesterolemia (n = 14). Among these, only 24 ADRs were classifiable as serious.Conclusions: The results of this study confirm that risperidone and aripiprazole are relatively well-tolerated therapeutic options for the treatment of a variety of psychiatric disorders in pediatric patients. However, in findings such as statistically significant increments of BMI and heart rate mean values, the variations over time in prolactin levels observed with risperidone and the differences between the two drugs remark the necessity of systematic monitoring.

Two well-established electrical insulators, graphene oxide and poly(methylmethacrylate) (PMMA) have been selectively exposed to controlled energy and fluence of ions. Ion micro beam has been propos...

SiC Schottky detectors, having a superficial active zone up to 80 micron depths and a thin surface metallization, are adapt to detect high energetic ions. In order to demonstrate their detection ability with high-energy resolution, a helium Rutherford backscattering spectroscopy (RBS) was employed to evaluate their detection efficiency, energy resolution in the region 1.0 – 6.0 MeV alpha ions, depth resolution and dependence on the ion beam current. The detector parameters dependencies on the surface passivation layers, ion energy and current are presented. The comparison of RBS analysis using a traditional barrier silicon detector is investigated, and the differences with SiC detector is presented and discussed.