Protons and carbon ions acceleration in the target-normal-sheath-acceleration regime using low-contrast fs laser and metal-graphene targets

fs pulsed lasers at an intensity of the order of 1018 W/cm2, with a contrast of 10−5, were employed to irradiate thin foils to study the target-normal-sheath-acceleration (TNSA) regime. The forward ion acceleration was investigated using 1/11 µm thickness foils composed of a metallic sheet on which a thin reduced graphene oxide film with 10 nm thickness was deposited by single or both faces. The forward-accelerated ions were detected using SiC semiconductors connected in time-of-flight configuration. The use of intense and long pre-pulse generating the low contrast does not permit to accelerate protons above 1 MeV because it produces a pre-plasma destroying the foil, and the successive main laser pulse interacts with the expanding plasma and not with the overdense solid surface. Experimental results demonstrated that the maximum proton energies of about 700 keV and of 4.2 MeV carbon ions and higher were obtained under the condition of the optimal acceleration procedure. The measurements of ion energy and charge states confirm that the acceleration per charge state is measurable from the proton energy, confirming the Coulomb–Boltzmann-shifted theoretical model. However, heavy ions cannot be accelerated due to their mass and low velocity, which does not permit them to be subjected to the fast and high developed electric field driving the light-ion acceleration. The ion acceleration can be optimized based on the laser focal positioning and on the foil thickness, composition, and structure, as it will be presented and discussed

Nanoparticles: Production, Characterization and Applications

The production of metallic nanoparticles using pulsed laser ablation in water is presented. The physical characterization of the produced nanoparticles is reported in terms of electronic microscopy, optical and mechanical properties, SPR, EDX, XPS and XRD spectroscopies. The applications of the prepared nanoparticles involve different scientific fields. In particular will be discussed their use to modify some properties of polymers, liquids and alloys. Special attention is devoted to the use of nanoparticles for polymeric laser welding, to the use as an image contrast medium in the biological environment and to the use of Au-NPs targeting for radiotherapy of cancer tissues

Laser ablation coupled to mass quadrupole spectrometry for analysis in the cultural heritage

A Nd:YAg laser operating at 1064 nm, 150 mJ, 3 ns pulse duration, 1-10 Hz repetition rate and 109 W/cm2 intensity is employed to irradiate ancient metallic and ceramic samples in high vacuum. A mass quadrupole spectrometer (MQS), operating between 1-300 amu with sensitivity better than 0.1 ppm, analyzes elements and compounds. Repetitive laser ablation removes in controlled manner the first surface layers of the irradiated samples so that the irradiation time can be correlated to the layer depth. MQS can be fixed to peculiar masses so that during the laser irradiation the mass yields can be plotted as a function of the sample depth. The technique permits to give the depth profiles of elements, chemical compounds and isotopes characterizing the composition of the analyzed samples. The analysis of ancient coins based on bronze and silver alloys and of old vitrified colored ceramics has been investigated to identify peculiar elements of the colored layers. Particularly, the lead isotopic ratios 208Pb/207Pb and 206Pb/207Pb were measured in bronze coins. Measurements were compared with the database of lead isotopic ratios in lead minerals extracted from old mines in the Mediterranean basin. In some cases, of special interest for Archeologists, the comparison has indicated that the lead employed for the coin production could have been extracted from mines of particular geographic sites. © Published under licence by IOP Publishing Ltd

Settling velocity of microplastics exposed to wave action

Microplastic (MP) debris is recognized to be one of the most serious threats to marine environments. They are found in all seas and oceanic basins worldwide, even in the most remote areas. This is further proof that the transport of MPs is very efficient. In the present study, we focus our attention on MPs’ transport owing to the Stokes drift generated by sea waves. Recent studies have shown that the interaction between heavy particles and Stokes drift leads to unexpected phenomena mostly related to inertial effects. We perform a series of laboratory experiments with the aim to directly measure MPs’ trajectories under different wave conditions. The main objective is to quantify the inertial effect and, ultimately, suggest a new analytical formulation for the net settling velocity. The latter formula might be implemented in a larger scale transport model in order to account for inertial effects in a simplified approach

A comparative analysis of old and recent Ag coins by XRF methodology

The investigation of silver coins dated since the first century B.C. up to recent times, coming from different countries in the world, has successfully generated a growing interest among numismatic researchers. The classification of these coins into originals, copies and imitations - according to their provenance and to their Ag content - has been performed by using the X-ray fluorescence (XRF) analysis. The archaeological challenge is to explain the large diversification of these coins, to determine the differences in composition, weight and physical aspects. A non-destructive physical method was employed to study the properties of silver coins (as in this case) allowing a detailed characterization of the analyzed samples. The XRF analysis was applied to the bulk, through an X-ray tube, and to the surface patina, through an electron beam

Therapies for bleomycin induced lung fibrosis through regulation of TGF-Β1 induced collagen gene expression

This review describes normal and abnormal wound healing, the latter characterized by excessive fibrosis and scarring, which for lung can result in morbidity and sometimes mortality. The cells, the extracellular matrix (ECM) proteins, and the growth factors regulating the synthesis, degradation, and deposition of the ECM proteins will be discussed. Therapeutics with particular emphasis given to gene therapies and their effects on specific signaling pathways are described. Bleomycin (BM), a potent antineoplastic antibiotic increases TGF-Β1 transcription, TGF-Β1 gene expression, and TGF-Β protein. Like TGF-Β1, BM acts through the same distal promoter cis -element of the COL1A1 gene causing increased COL1 synthesis and lung fibrosis. Lung fibroblasts exist as subpopulations with one subset predominately responding to fibrogenic stimuli which could be a specific cell therapeutic target for the onset and development of pulmonary fibrosis. J. Cell. Physiol. 211: 585–589, 2007. © 2007 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/55994/1/20972_ftp.pd

wetting ability modifications in biocompatible polymers induced by pulsed lasers

Wetting ability was measured in the surface of different biocompatible polymers, such as mylar, polyethylene, poly-methyl-methacrylate and teflon. Nanosecond pulse lasers at intensities of the order of 108 W/cm2 were employed at different doses to irradiate the polymeric surfaces and to induce wetting ability modifications due to the chemical and physical surface changes vs. irradiation time and laser wavelength. In particular, the contact angle as a function of the surface roughness was investigated, as will be presented and discussed