We report the development of a system to feed pulsed magnetic stress to biological samples. The device is based on a RLC circuit that transforms the energy stored in a high voltage capacitor into a magnetic field inside a coil. The field has been characterized and we found that charging the capacitor with 24 kV results in a peak field of 0.4 T. In order to test its effect, we applied such a stress to the Drosophila melanogaster model and we examined its bio-effects. We analysed, in the germ cells, the effects on the control of specific DNA repetitive sequences that are activated after different environmental stresses. The deregulation of these sequences causes genomic instability and chromosomes breaks leading to sterility. The magnetic field treatment did not produce effects on repetitive sequences in the germ cells of Drosophila. Hence, this field doesn't produce deleterious effects linked to repetitive sequences derepression.

Due to the diffusion of severe pathogens, everyday life is exposed to the risks of contracting severe diseases. For this reason, efficient antimicrobial surfaces are of paramount importance. In this work we present the first evidences of a new technique to obtain an antibacterial ultra high molecular weight polyethylene based on a non- stoichiometric, visible light responsive, titanium oxide coating. The coating was obtained through a process in which titanium ions, resulting from laser ablation of a corresponding target, were accelerated and implanted on the samples. The samples were tested against a Staphylo- coccus aureus strain, in order to assay their antimicrobial efficacy. Results show that this treatment strongly dis- courages bacterial colonization of the treated surfaces.

A single-crystal CVD diamond detector (DD) of a sandwich structure was used for measurement of soft X-rays and ions emitted from plasmas obtained with the use the PALS laser system in Prague. The detector was fabricated in the Institute of Nuclear Physics PAN in Cracow with the use of diamond material obtained from Element Six, Inc. In the laser experiment, the responses of the detector to X-rays and ions were compared to the responses of an ion collector (IC). The signals from the DD proved to be much different to the ones from the IC which is explained by different mechanisms of producing current in both detectors. Due to high sensitivity, the DD is useful for measurement of fast protons. Both detectors can be used for simultaneous measurement of soft X-rays and ions from the same laser shot and the data obtained are complementary.

We show that, in particular experimental conditions, the time course of the radiant fluxes, measured from a bioluminescent emission of a Vibrio harveyi related strain, collapse after suitable rescaling onto the Gumbel distribution of extreme value theory. We argue that the activation times of the strain luminous emission follow the universal behavior described by this statistical law, in spite of the fact that no extremal process is known to occur.

We present an effective dynamical model for the onset of bacterial bioluminescence, one of the most studied quorum sensing-mediated traits. Our model is built upon simple equations that describe the growth of the bacterial colony, the production and accumulation of autoinducer signal molecules, their sensing within bacterial cells, and the ensuing quorum activation mechanism that triggers bioluminescent emission. The model is directly tested to quantitatively reproduce the experimental distributions of photon emission times, previously measured for bacterial colonies of Vibrio jasicida, a luminescent bacterium belonging to the Harveyi clade, growing in a highly drying environment. A distinctive and novel feature of the proposed model is bioluminescence 'quenching' after a given time elapsed from activation. Using an advanced fitting procedure based on the simulated annealing algorithm, we are able to infer from the experimental observations the biochemical parameters used in the model. Such parameters are in good agreement with the literature data. As a further result, we find that, at least in our experimental conditions, light emission in bioluminescent bacteria appears to originate from a subtle balance between colony growth and quorum activation due to autoinducers diffusion, with the two phenomena occurring on the same time scale. This finding is consistent with a negative feedback mechanism previously reported for Vibrio harveyi.

Experimental results are obtained concerning the target polarization, which aptly characterizes the laser ablation. The charge separation in the laser-produced plasma, structure of the ion front, and the current of fast electrons expanding into the vacuum chamber ahead of ions are of crucial importance for the interpretation of multi-peak structure of target currents appearing much later than the laser pulse. Of particular interest is the correlation between the partial maxima in the time-resolved target current and the square root of mass number of ionized species. The late-time negative charging of targets provides evidence for production of very slow ions by ionization of neutrals ablated at the target crater by radiation from plasma produced by 23 ns excimer krypton fluoride laser.

In this work, the properties of laser plasma produced by ablation of pure and doped targets have been studied. A KrF laser, 0 = 248 nm and 20 ns of pulse duration, was used to induce ablation. Pure Cu, Cu with 2% of Be and Cu with 4% of Sn targets of 500 m thickness were ablated to assess the influence of these admixture on the emission characteristics of plasma ions. The utilized laser irradiance values were 0.6, 1.2 and 2.4 ×108 W/cm2. It was observed that the emission of Cu ions exhibited a higher gain from the Cu/Be and Cu/Sn plasmas with respect to the pure Cu one. We also performed studies of the temperature, ion velocity and charge angular distribution for the three plasmas. Under the above conditions, the analyses of the experimental data demonstrated that the influence of these admixtures on the emission of Cu ions played a not negligible role which enhances the interest in plasmas by alloy targets. © 2012 Elsevier B.V. All

In this work, we report on the characterization of pulsed soft X-rays emitted from laser-produced plasma by different targets. The measurements were performed in a vacuum stainless-steel chamber at 10-7 mbar .The plasma was generated by a pulsed KrF excimer laser of 248 nm laser wavelength, operating at single shot and having a pulses of 23 ns FWHM. The beam was focused on pure Si, Cu and Ta targets. The laser energies were 40, 80 and 120 mJ, concentrated onto a spot of about 0.01 cm2, with a resulting irradiance of 1.7, 3.5 and 5.2x108 Wcm-2. The utilized detector was a very sensitive Faraday cup which opportunely biased was able to record time resolved signals of X-rays and to estimate their energy. The found X-rays energy values were compared to the ion temperature of the target plasma fitting the time resolved ion current signals by the shifted Maxwell-Boltzmann velocity distribution.

In light of recent speculations on a potentially increased speed of the radioactive decay of α-emitters embedded in a metallic matrix at very low temperature, four high-purity Cu disks deep-implanted with 209Bi were prepared. The disks were irradiated in a high-flux reactor to transmute the 209Bi into 210Po. After the irradiation, the 210Po activity was measured for all four disks. While two of the disks were stored at room temperature, the other two disks were stored in a sealed container submerged in liquid helium (T = 4.2 K) for approximately 200 days. After the storage time the 210Po-activity measurements were repeated and the 210Po half-life was calculated for each sample. No difference between the half-lives for the four samples could be detected within the uncertainties of the measurements. In other words, the results of this study show no evidence for an increase of activity for α emitters embedded in a metallic matrix at very low temperature.

Ions of different elements were generated by laser-induced-plasma and accelerated by a two adjacent cavities. Therefore, the ions were undergone a double acceleration imparting a maximum ion energy of 160 keV per charge state. We analyzed the extracted charge from a Cu target as a function of the accelerating voltage. At 60 kV of total accelerating voltage, the maximum current peak was of 5.3 mA. The ion flux resulted of 3.4x1011 ions/cm2. The normalized emittance measured by pepper pot method at 60 kV was of 0.22 π mm mrad. By this machine, biomedical materials as UHMWPE were implanted with carbon and titanium ions. At a total ion flux of 2x1015 ions/cm2 the polyethylene surface increased its micro hardness of about 3-hold measured by the scratch test. Considering the ion emission cone dimension, we estimated a total extracted charge per pulse of 200 nC.

La conservazione e il restauro di manufatti in argento e sue leghe di interesse storico, artistico e archeologico sono uno dei temi di attenzione e dibattito nel campo dei beni culturali. In passato, l’insieme delle operazioni finalizzate al restauro di un qualsivoglia manufatto storico-artistico, non sempre si sono rivelate adeguate a rallentarne il naturale processo di degrado nel tempo. Da qui la consapevolezza di impostare e perfezionare tecniche di restauro sulla base di conoscenze scientifiche sempre più approfondite e con conseguente impiego di metodi d’indagine non distruttivi. La caratterizzazione qualitativa e quantitativa degli elementi e dei composti del manufatto, non solo rappresenta uno strumento prezioso nel campo della ricerca storica (origine, datazione, ecc.), ma è anche di fondamentale importanza per una migliore comprensione e prevenzione dei processi di alterazione cui il manufatto è soggetto. Contemporaneamente lo studio e l’identificazione dei prodotti di corrosione rappresentano un prerequisito essenziale per il corretto restauro di antichi manufatti argentei e un basilare contribuito nel campo della conservazione. Il presente lavoro è finalizzato alla conoscenza approfondita e completa dell’applicabilità e dell’efficacia della tecnica di pulitura di manufatti archeologici in argento e sue leghe usando un laser UV (laser cleaning). A tale scopo gli interventi di pulitura laser sono stati monitorati da indagini di diffrattometria e fluorescenza a raggi X condotte prima, durante e dopo i trattamenti laser. Tali indagini hanno permesso di valutare la concentrazione superficiale degli elementi costituenti le patine e gli effetti fotochimici indotti dal laser.

Laser ion sources offer the possibility to get ion beam useful to improve particle accelerators. Pulsed lasers at intensities of the order of 108 W/cm2 and of ns pulse duration, interacting with solid matter in vacuum, produce plasma of high temperature and density. The charge state distribution of the plasma generates high electric fields which accelerate ions along the normal to the target surface. The energy of emitted ions has a Maxwell–Boltzmann distribution which depends on the ion charge state. To increase the ion energy, a post-acceleration system can be employed by means of high voltage power supplies of about 100 kV. The post acceleration system results to be a good method to obtain high ion currents by a not expensive system and the final ion beams find interesting applications in the field of the ion implantation, scientific applications and industrial use. In this work we compare the electromagnetic and geometric properties, like emittance, of the beams delivered by pure Cu, Y and Ag targets. The characterization of the plasma was performed by a Faraday cup for the electromagnetic characteristics, whereas a pepper pot system was used for the geometric ones. At 60 kV accelerating voltage the three examined ion bunches get a current peak of 5.5, 7.3 and 15 mA, with a normalized beam emittance of 0.22, 0.12 and 0.09 mm mrad for the targets of Cu, Y, and Ag, respectively.

Laser ion sources offer the possibility to generate ion beams suitable for particle accelerators. Today many laboratories, as well as the LEAS, are involved in the development of compact accelerators, easy to be installed in little laboratories. Pulsed lasers at intensities of the order of 108 W/cm2 and of ns pulse duration, interacting with solid matter in vacuum, produce plasma of high energy, temperature and density. The charge state distribution of the plasma generates high electric fields which accelerate ions along the normal to the surface of the ablated target. The energy of the emitted ions is of the order of some hundreds of eV and these have got a shifted Maxwell-Boltzmann distribution which depends on the ion charge states. To increase the ion energy, a post-acceleration system can be employed by means of high voltage power supplies of about 100 kV. The post acceleration system results in a good method to obtain high ion currents using a not expensive system and the final ion beams find interesting applications in the field of ion implantations, scientific applications and industrial use. In this work we study the electromagnetic and geometric properties, like the emittance, of the beams delivered by pure Cu targets. Plasma’s characterization was performed using a Faraday cup for the electromagnetic characteristics, while for the geometric ones a pepper pot system has been applied. This technique consists of a pierced mask in order to measure the divergence of the ions that can pass through it. To impress the ions, radio-chromic films type GAFCHROMIC EBT-1 were used. We study the emittance for different values of accelerating voltage: 20, 30, 40, 50 and 60 kV. Applying a laser irradiance of 0.1 GW/cm2 and 60 kV of accelerating voltage, we obtain 5.5 mA of output current and a normalized beam emittance of 0.2 π mm mrad. The brightness of the beams was 137 mA( mm mrad)-2.

Silver artefacts and particularly ancient silver artefacts present the serious problem of the black look due to ambient contamination. The black colour is the consequence of the layer forming on the surface made of acanthite and jalpaite, both compounds are sulphur composts. Recently UV laser cleaning technique has demonstrated to be very promising in processing of cultural artefacts. To operate on artefacts without to contaminate the bulk, first we determined the laser fluence threshold of the bulk, second we controlled the surface compounds and at the end we operated the laser irradiation. In this work we utilised certified silver and silver/copper samples in order to perform preliminary studies. The threshold fluence we found were 780 and 510 mJ/cm2 for the Ag pure and for the Ag/Cu alloy, respectively. The jalpaite concentration on Ag/Cu sample increased after the laser dose of 25 J/cm2, while for higher laser dose its value lowered pointing out that complex processes take part during the laser application. As a successful of our studies we applied the technique on a Carlino coin made of silver coined in 1689 under King Carlo II. The analyses were performed by two different techniques able to find the percentage of elements and the chemical compounds; the EDXRF and the XRD. We found that the sulphur concentration decreased on laser dose. Operating on the coin up to a dose of 280 J/cm2 the sulphur concentration deceases up to 20 %, while the coin look becomes clear just after a 50 J/cm2.

In this study, the evidence of electron-dense magnetic inclusions with polyhedral shape in the cytoplasm of Harveyi clade Vibrio strain PS1, a bioluminescent bacterium living in symbiosis with marine organisms, led us to investigate the behavior of this bacterium under exposure to static magnetic fields ranging between 20 and 2000 Gauss. When compared to sham-exposed, the light emission of magnetic field-exposed bacteria growing on solid medium at 18°C ±0.1°C was increased up to two-fold as a function of dose and growth phase. Stimulation of bioluminescence by magnetic field was more pronounced during the post-exponential growth and stationary phase, and was lost when bacteria were grown in the presence of the iron chelator deferoxamine, which caused disassembly of the magnetic inclusions suggesting their involvement in magnetic response. As in luminescent Vibrio spp. bioluminescence is regulated by quorum sensing, possible effects of magnetic field exposure on quorum sensing were investigated. Measurement of mRNA levels by reverse transcriptase real time-PCR demonstrated that luxR regulatory gene and luxCDABE operon coding for luciferase and fatty acid reductase complex were significantly up-regulated in magnetic field-exposed bacteria. In contrast, genes coding for a type III secretion system, whose expression was negatively affected by LuxR, were down-regulated. Up-regulation of luxR paralleled with down-regulation of small RNAs that mediate destabilization of luxR mRNA in quorum sensing signaling pathways. The results of experiments with the well-studied Vibrio campbellii strain BB120 (originally classified as Vibrio harveyi) and derivative mutants unable to synthesize autoinducers suggest that the effects of magnetic fields on quorum sensing may be mediated by AI-2, the interspecies quorum sensing signal molecule.

The spreading of pathogens represents a serious threat for human beings. Consequently, efficient antimicrobial surfaces are needed in order to reduce risks of contracting severe diseases. In this work we present the first evidences of a new technique to obtain a highly antibacterial Ultra High Molecular Weight Polyethylene (UHMWPE) based on a non-stoichiometric titanium oxide coating, visible-light responsive, obtained through ion implantation.

Ion production

A new LIS configuration was studied and realized in order to generate and accelerate ions of different elements. This ion source consisted of a laser-induced plasma from solid targets where the plume was made to expand before the action of the accelerating field. The accelerating field was reached by the application of two high voltage power supplies of different polarity. Therefore, the ions were undergone to double acceleration which can imprint a maximum ion energy up to 160keV per charge state. We analyzed the extracted charge from a Cu target as a function of the accelerating voltage at the laser fluence of 1.7 and 2.3 J/cm^2. At 60kV of total accelerating voltage and higher laser fluence, the maximum ion dose was of 10^12 ions/cm^2. Under this last conditions the maximum output current was 5 mA and the emittance measured by pepper pot method resulted of 0.22 π mm mrad. By this machine biomedical materials as UHMWPE were implanted with carbon and titanium ions. At doses of 6x10^15 ions/cm^2 the polyethylene surface increased its micro hardness of about 3-hold measured by the scratch test.

The properties of pulse laser ablation of Cu and Cu98/Be2 materials are studied and the differences in emission of Cu ions are emphasized. The iodine high-power laser system PALS and a KrF laser were used to perform the experiments at the fundamental harmonics λ = 1.315 µm and  = 248 nm delivering energy up to 500 J and 600 mJ, respectively. Pure Cu and Cu98/Be2 alloy targets of 50 µm, 500 µm and 1000 µm in thickness were ablated to measure the influence of the Be admixture on the emission of Cu ions. The alloy Cu98/Be2 was chosen due to the well defined amount of a beryllium admixture in the plasma in contrary to the incidental amount of carbon, oxygen and hydrogen impurities chemisorbed on target surfaces of Cu and Cu98/Be2 samples. It was approved that the emission of Cu ions driven by the KrF laser exhibits a higher gain from the Cu98/Be2 plasma in contrary to the Cu plasma. The fast ion emission induced by laser intensities near the threshold value is significantly affected by the emission of ionized impurities chemisorbed on the target surface and by repetitive outbursts of fast generated ions. Under these conditions the influence of the 2% Be admixture on the emission of Cu ions plays only a minor role.

In this paper we report the experimental results of the study of evaluation of an UV laser cleaning treatment on a bronze bell outdoor, dating from the second half of the 600. Energy dispersive X-ray fluorescence (EDXRF) non-destructive analysis was performed on the bell before, during and after the cleaning treatment in order to assess the laser ablation threshold, to define the efficiency of laser cleaning process, to avoid possible damage of laser on the bell, to determine the concentration of the constituents of both the patina and the alloy. In particular, an EDXRF portable apparatus was used in order to evaluate the variation of concentration of sulfur, chlorine, calcium, copper, lead and tin during the laser cleaning.

Nowadays, the employment and development of fast current pulses require sophisticated systems to perform measurements. Rogowski coils are used to diagnose cylindrical shaped beams; therefore, they are designed and built with a toroidal structure. Recently, to perform experiments of radiofrequency biophysical stresses, flat transmission lines have been developed. Therefore, in this work we developed a linear Rogowski coil to detect current pulses inside flat conductors. The system is first approached by means of transmission line theory. We found that, if the pulse width to be diagnosed is comparable with the propagation time of the signal in the detector, it is necessary to impose a uniform current as input pulse, or to use short coils. We further analysed the effect of the resistance of the coil and the influence of its magnetic properties. As a result, the device we developed is able to record pulses lasting for some hundreds of nanoseconds, depending on the inductance, load impedance, and resistance of the coil. Furthermore, its response is characterized by a sub-nanosecond rise time (∼100 ps). The attenuation coefficient depends mainly on the turn number of the coil, while the fidelity of the response depends both on the magnetic core characteristics and on the current distribution along the plane conductors.

We developed an ion accelerator with a double accelerating gap system supplied by two power generators of different polarity.-The ions were generated by laser ion source technique. The laser plasma induced by an excimer KrF laser, freely expanded before the action of accelerating fields. After the first gap action, the ions were again accelerated by a second gap. The total acceleration can imprint a maximum ion energy up to 160 keV per charge state. We analyzed the extracted charge from a Cu target as a function of the accelerating voltage at laser energy of 9, 11 and 17 mJ deposited on a spot of 0.005 cm2. The peak of current density was 3.9, 5.3 mA for the lower and medium laser energy at 60 kV. At the highest laser energy, the maximum output current was 11.7 mA with an accelerating voltage of 50 kV. The maximum ion dose was estimated to be of 1012 ions/cm2. Under the condition of 60 kV accelerating voltage and 5.3 mA output current the normalized emittance of the beam measured by pepper pot method was 0.22 π mm mrad.

Laser ion sources offer the possibility to get ion beam utilizable to improve particle accelerators. Today many laboratories, as well as the LEAS, are employed to develop accelerators of the dimensions very contained to be installed in little laboratories and hospitals. Pulsed lasers at intensities of the order of 108 W/cm2 and of ns pulse duration interacting with solid matter in vacuum, plasma of high temperature and density is produced. The charge state distribution of the plasma generates high electric fields which accelerate ions along the normal to the target surface. The energy of emitted ions has a Maxwell Boltzmann distribution which depends on the ion charge state. To increase the ion energy, a post-acceleration system can be employed by means of high voltage power supplies of about 100 kV. The post acceleration system results a good method to obtain high ion currents by a not expensive system and the final ion beams find interesting applications in the field of the ion implantations, adrotherapy, scientific applications and industrial use. In this work we compare the electromagnetic and geometric properties, like the emittanza, of the beams delivered by a Cu and Y target. The characterization of the plasma was performed by a Faraday cup for the electromagnetic characteristics, whereas a pepper pot system for the geometrical ones. At 60 kV accelerating voltage and 5.5 mA output current the normalized beam emittance resulted of 0.22 π mm mrad for the Cu target, while under the same accelerating voltage but with 7.4 mA output current a lower normalized beam emittance value was reached for the Y target. It resulted of 0.14 π mm mrad. The brightness of the beams was of 114 and 378 mA( mm mrad)-2 for the Cu and Y target, respectively. When Ag targets were utilised, we implanted an AISI 420 stainless steel by a dose of 10x1015 inos/cm2. Besides, the laser ion sources have got very good properties to feed large machines.

In this work, we performed experiments of absorption of hydrogen and deuteriumgas by Pd thin films, and we compared the behavior of these samples to unprocessed films. We also employed a continuous wave He–Ne laser to irradiate the samples inside the chamber during the treatment, in order to increase the gas absorption. Using a scanning electron microscope (SEM) and an electron probe micro-analyzer (EDX), we observed structures like spots on the surface of the treated samples. Inside the spots, elements other than Pd were found. Based on these results, we determined that gas loading is an effective way to transmute elements, and the laser action has been a very effective way to increase morphological changes in the treated samples.

In this work two different techniques to modify the polymeric surfaces are compared; Laser irradiation and ion implantation were performed on Ultra High Molecular Weight Polyethylene (UHMWPE) samples. The irradiation treatment was performed by using two different laser sources operating in the UV and IR range, applying many laser shots in air atmosphere on the polymer surface. Ion implantation was performed using a new LIS (Laser Ion Source) accelerator with an accelerating voltage of 40 kV. Contact angle, roughness and Fourier Transform Infra Red (FT-IR) measurements were performed on the samples before and after the two treatments in order to obtain information on the UHMWPE modification.

We study the velocity distribution of ions delivered by plasma whihs is induced by UV Laser.

Pulsed lasers at intensities of the order of 1010 W/cm2 interacting with solid matter in vacuum, produce hot plasmas at high temperatures and densities. The charge state distributions of the plasma generate a high electric field, which induces high ion acceleration along the normal to the target surface. The high yield of the emitted ions can generate a near constant current by using repetitive pulses irradiating thick targets. In order to increase ion energy, a post-acceleration system can be employed by using acceleration voltages above 10 kV. Special ion extraction methods can be employed to generate the final ion beam, which is multi-ionic and multi-energetic, due to the presence of different ion species and of different charge states. In this article four different methods of post ion acceleration, employed at the INFN-LNS of Catania, at the IPPLM of Warsaw, at the INFN of Lecce and at the LPI of Moscow, are presented, discussed and compared. All methods are able to implant ions in different substrates at different depth and at different dose-rates.

In this work, we present a new pulsed laser ablation technique to obtain energetic ion beams. The accelerator we made is a compact device able to extract and accelerate the ionic components of plasma up to 160 keV per charge state. It is composed by a generating chamber containing an expansion chamber used like first electrode. Next, a second electrode connected to ground and a third electrode connected to negative voltage are used. The third electrode is used also as Faraday cup. By the analysis of the ion signals we studied the plume parameters such as TOF accelerated signals, charge state, and divergence.

Proton beams by Titanuim target

In thisworkwepresentastudyonprotonbeamsextractionfromaplasmageneratedbypulsedlaser ablation oftitaniumandtantalumdisks.ThedeviceusedwasthePLATONElaserionsourceoperatingat the LEASLaboratoryinLecce,Italy.ItisbasedonaKrFlaseroperatingatlowirradiance(109–1010 W/cm2) and nspulseduration.Theprotonandionsemissionwasanalyzedbythetime-of-flight techniqueusing a Faradaycupasioncollectorandanelectrostaticbarriertoidentifytheparticles.Studiesonthe produced protonsandionsatdifferentlaserirradiancevalueswereperformed.Theextractedbeams showedhighproton flux upto1010 protons/cm2.

The production of proton beams by ns low intensity pulsed excimer laser ablation of solid hydrogenated targets is investigated. The targets used were solid disks produced by compression of TiH2 and CaH2 powder. The ion emission was analyzed by the time-of-flight (TOF) technique using a Faraday Cup as ion collector. We performed preliminary studies on the produced plasma in free expansion mode and under an accelerating voltage up to 15 kV, for different laser fluence values. The TOF spectra deconvolution through Maxwell-Boltzmann shifted function permitted us to evaluate the plasma temperature, particle density, ion charge state distributions, proton and ion energy and their relative yield. Using these special targets, we were able to obtain protons, titanium and calcium ion beams with a kinetic energy of some tens of keV.

We present the study and the analyses of a transmission line for radiofrequency (RF) irradiation of bacteria belonging to Vibrio harveyi-related strain PS1, a bioluminescent bacterium living in symbiosis with many marine organisms. The bioluminescence represents a new biologic indicator which is useful for studying the behaviour of living samples in the presence of RF waves due to the modern communication systems. A suitable transmission line, used as an irradiating cell and tested up to the maximum frequency used by the global system for mobile communications and universal mobile telecommunications system transmissions, was characterized. In this experiment, the RF voltage applied to the transmission line was 1V. Due to short dimensions of the line and the applied high frequencies, standing waves were produced in addition to progressing waves and the electric field strength varies particularly along the longitudinal direction. The magnetic field map was not strongly linked to the electric one due to the presence of standing waves and of the outgoing irradiation. RF fields were measured by two homemade suitable probes able to diagnostic fields of high frequency. The field measurements were performed without any specimens inside the line. Being our sample made of living matter, the real field was modified and its value was estimated by a simulation code. The bioluminescence experiments were performed only at 900MHz for two different measured electric fields, 53 and 140V/m. The light emission was measured right from the beginning and after 7 and 25 h. Under RF irradiation, we found that the bioluminescence activity decreased. Compared with the control sample, the diminution was 6.8% and 44% after 7 and 25 h of irradiation, respectively, both with the low or high field. No changes of the survival factor for all the samples were observed. Besides, to understand the emission processes, we operated the deconvolution of the spectra by two Gaussian curves. The Gaussian peaks were approximately centered at 460 nm and 490 nm. The 490 nm peak was higher than the control one. Under RF, the 490 nm peak decreased compared to the 460 nm one. The decreasing was stronger for the sample in the higher field. The ratio of the emission area of the 490 nm to 460 nm was 5 for the control sample. It decreased up to 1.6 for the samples under RF. The bioluminescence improves the DNA repair by photoreactivation, and there is evidence that photolyase is preferentially activated by blue/violet light. Our finding suggests that RF exposure may stimulate DNA repair by shifting the emission spectra from blue/green (490 nm) to blue/violet (460 nm). VC 2012 American Institute of Physics.

Time-of-flight spectra of C, Fe, and Si ions produced with the use of a KrF excimer laser have been analyzed. Ion currents were collected by Faraday cups and their responses were analyzed using a detector signal function. This function was derived from shifted Maxwell-Boltzmann velocity distribution, in order to uncover the contribution of partial currents of all the ionized species constituting the expanding plasma plume. The deconvolution method allowed to estimate parameters of the plasma, such as the ion temperature and the center-of-mass velocities of expanding ionized species. Furthermore, the linear charge-state dependence of the center-of-mass velocity has revealed the contribution of hydrodynamic and electrostatic forces to the expansion velocity of the plasma. The nearly isotropic distribution of the center-of-mass velocity indicates

Magnetic field effects are diffused among living organisms. They are mainly studied with static or extremely low frequency fields, while scarce information is available for pulsed fields. This work is devoted to the study of the interaction between Drosophila melanogaster, both adults and larvae, and pulsed magnetic fields. We exposed the organisms to a peak field of 0.4 T, lasting for about 2 μ s, within an ad hoc designed copper coil. Adult individuals didn't present any deregulation of repetitive sequences in the germ line of Drosophila. Instead, we noticed a marked magnetic field effect in larvae. Polytene chromosomes coming from treated individuals showed the presence of heat shock puffs; the same organisms revealed also an upregulation of the genes encoding for the Hsp70 protein. These observations suggest that the larvae underwent an oxidative stress caused by the modulation of free radicals' yield induced by the magnetic field through a radical pair mechanism.

In this work, the characteristics of laser plasma produced by ablation of pure and doped targets are studied. An excimer KrF laser was used to induce ablation. Pure Cu, Cu with 2% of Be, and Cu with 4% of Sn targets were ablated to evaluate the influence of these admixture on the emission of Cu ions. It was observed that the emission of ions exhibited a higher gain from the Cu/Be and Cu/Sn targets with respect to the pure Cu one. We also performed studied of ion velocity and charge angular distribution.

A space-resolved charge density of ions is derived from a time-resolved current of ions emitted from laser-produced plasma and expanded into the vacuum along collision-free and field-free paths. This derivation is based on a similarity relationship for ion currents with “frozen” charges observed at different distances from the target. This relationship makes it possible to determine a map of ion charge density at selected times after the laser plasma interaction from signals of time-of-flight detectors positioned at a certain distance from the target around a target-surface normal. In this work, we present maps of the charge density of ions emitted from Cu and polyethylene plasmas. The mapping demonstrates that bursts of ions are emitted at various ejection angles fn with respect to the target-surface normal. There are two basic directions f1 and f2, one belonging to the fastest ions, i.e., protons and carbon ions, and the other one to the slowest ions being a part of each plasma plume.

Bacteria undergoing environmental effects is extremely interesting for structural, mechanistic, and evolutionary implications. Luminescent bacteria that have evolved in a specific ambient have developed particular responses and their behavior can give us new suggestions on the task and production of luciferina proteins. To analyze the UV interaction under controlled laboratory conditions, we used photoluminescent bacterial strains belonging to a new species evolutionarily close to Vibrio harveyi sampled from a coastal cave with a high radon content that generates ionizing radiation. The survival of the bacterial strains was analyzed, in the light and in the dark, following a variety of genotoxic treatments including UV radiation exposure. The strains were irradiated by a germicide lamp. The results demonstrated that most of the strains exhibited a low rate of survival after the UV exposure. After irradiation by visible light following the UV exposure, all strains showed a high capability of photoreactivation when grown. This capability was quite unexpected because these bacteria were sampled from a dark ambient without UV radiation. This leads us to hypothesize that the photoreactivation in these bacteria might have been evolved to repair DNA lesions also induced by different radiation sources other than UV (e.g., x-ray) and that the luminescent bacteria might use their own light emission to carry out the photoreactivation. The high capability of photoreactivation of these bacteria was also justified by the results of deconvolution. The deconvolution was applied to the emission spectra and it was able to show evidence of different light peaks. The presence of the visible peak could control the photolysis enzyme.

Plasmas induced by UV laser ablation have been studied and analysed using timeof- flight measurements. A KrF laser beam of 23 ns FWHM time duration was focused into Si and Nb targets with a moderate laser fluence of 2 J/cm2. A suitable theoretical expressions were derived for fitting the recorded ion current under the assumption of a “shifted” Maxwell- Boltzmann velocity distribution. The deconvolution of time resolved ion current signals, taking into account a multi-mode velocity distribution has revealed that the contribution of the different charge states of ions in the plasma induces electric field which accelerate the expanding plasma along the target normal.