Numerous applications of non-equilibrium (cold, low temperature) plasmas require those plasmas to operate at atmospheric pressure. Achieving non-equilibrium at atmospheric pressure is difficult since ...the ionization growth is very fast at such a high pressure. High degree of ionization on the other hand enables transfer of energy between electrons and ions and further heating of the background neutral gas through collisions between ions and neutrals. Thus, all schemes to produce non-equilibrium plasmas revolve around some form of control of ionization growth. Diagnostics of atmospheric pressure plasmas is difficult and some of the techniques cannot be employed at all. The difficulties stem mostly from the small size. Optical emission spectroscopy and laser absorption spectroscopy require very high resolution in order to resolve the anatomy of the discharges. Mass analysis is not normally applicable for atmospheric pressure plasmas, but recently systems with triple differential pumping have been developed that allow analysis of plasma chemistry at atmospheric pressures which is essential for numerous applications. Application of such systems is, however, not free from problems. Applications in biomedicine require minimum heating of the ambient air. The gas temperature should not exceed 40 °C to avoid thermal damage to the living tissues. Thus, plasmas should operate at very low powers and power control is essential. We developed unique derivative probes that allow control of power well below 1 W and studied four different sources, including dielectric barrier discharges, plasma needle, atmospheric pressure jet and micro atmospheric pressure jet. The jet operates in plasma bullet regime if proper conditions are met. Finally, we cover results on treatment of bacteria and human cells as well as treatment of plants by plasmas. Localized delivery of active species by plasmas may lead to a number of medical procedures that may also involve removal of bacteria, fungi and spores.
Long-time background spectra of a well-shielded HPGe detector are recorded in order to estimate the contribution of inelastic neutron scattering on Ge nuclei in the low-energy part of the spectra, ...mainly influenced by elastic neutron collisions. It is shown that using intensities of several asymmetric peaks characteristic of Ge(n,n′) reactions and some properties of detectors (ability for total absorption or total transmission of gamma photons emitted during de-excitation of Ge nuclei) the contribution of Ge(n,n′) reactions to the low-energy part of spectra can be evaluated. The obtained result is in good agreement with results of simulations available in the literature.
We present results of continuous monitoring of the cosmic-ray muon intensity at the ground and shallow underground level at the Belgrade cosmic-ray station. The cosmic-ray muon measurements have been ...performed since 2002, by means of plastic scintillation detectors. The scintillator counts are corrected for atmospheric pressure for the whole period of measurements and, as well, for vertical temperature profile for the period of the last six years. The results are compared with other correction methods available. One-hour time series of the cosmic-ray muon intensity at the ground level are checked for correlation with European neutron monitors, with emphasis on occasional extreme solar events, e.g. Forbush decreases.
Neutrons produced by muons at 25 mwe Dragić, A; Aničin, I; Banjanac, R ...
Journal of physics. Conference series,
01/2013, Letnik:
409, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The flux of fast neutrons produced by CR muons in lead at the depth of 25 mwe is measured. Lead is a common shielding material and neutrons produced in it in muon interactions are unavoidable ...background component, even in sensitive deep underground experiments. A low background gamma spectrometer, equipped with high purity Ge detector in coincidence with muon detector is used for this purpose. Neutrons are identified by the structure at 692 KeV in the spectrum of delayed coincidences, caused by the neutron inelastic scattering on Ge-72 isotope. Preliminary result for the fast neutron rate is 3.1(5) × 10−-4n/cm2 · s.
Cosmic ray muons stopped in 5 cm thick plastic scintillators at surface and at depth of 25 m.w.e are studied. Apart from the stopped muon rate we measured the spectrum of muon decay electrons and the ...degree of polarization of stopped muons. Preliminary results for the Michel parameter yield values lower than the currently accepted one, while the asymmetry between the numbers of decay positrons registered in the upper and lower hemispheres appear higher than expected on the basis of numerous earlier studies.
The effects of acute exposure to cadmium (Cd) on the blood antioxidant defense system, lipid peroxide concentration and hematological parameters, as well as the possible protective role of vitamin E ...were studied. Male Wistar albino rats (3 months old) were treated with cadmium (0.4 mg Cd/kg b.m., i.p., 24 h before the experiment) or with vitamin E + Cd (20 IU Vit E/kg b.m., i.m., 48 h + 0.4 mg Cd/kg b.m., i.p., 24 h before the experiment). The hematological parameters were assessed: red blood cell counts, hematocrit value and hemoglobin concentration were significantly decreased in the blood of Cd-treated rats. Intoxication with cadmium was also followed by significantly increased lipid peroxide concentrations. We also observed increased activity of antioxidant defense enzymes: copper zinc containing superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione-S-transferase as well as concentrations of non-enzymatic components of antioxidant defense system: reduced glutathione, vitamin C and vitamin E. Pretreatment with vitamin E exhibited a protective role on the toxic effects of cadmium on the hematological values, lipid peroxide concentration as well as on enzymatic and non-enzymatic components of antioxidant defense system.
The proposed influence of cosmic rays on cloud formation is tested for the effect of sudden intensity changes of CR (Forbush decreases) on cloudiness. An attempt is made to widen the investigated ...period covered by satellite observation of cloudiness. As an indicator of cloud cover, the diurnal temperature range (DTR - a quantity anticorrelated with cloudiness) is used. The superposed epoch analysis on a set of isolated Forbush decreases is conducted and the results for a region of Europe are presented. The effect of Forbush decrease on DTR is statistically significant only if the analysis is restricted to high amplitude FDs (above the threshold value of 7% with the respect to undisturbed CR intensity). The magnitude of the effect on DTR is estimated to be (0.38 ± 0.06) °C.
We measured the time-differentiated spectrum of the 252Cf source as seen by an high-purity germanium detector triggered by the NE213 liquid scintillator detector. The detectors are off-line coincided ...from the event-by-event list formed with 10ns resolution by the quad FADC unit of the CAEN N1728B type. The signatures of the processes induced by fast and slow neutrons, both within the detector itself and in its environment, appear completely separated. The processes induced by fast neutrons are found in the prompt part of the time spectrum and those induced by thermal neutrons in the long tail of delayed coincidences. We analyse the time behaviour of spectral structures at 692 keV, which are the signatures of inelastic neutron scattering on Ge-72, and comment on its suitability for determination of the fast neutron flux in general, and in the digital gamma-ray spectroscopy in particular.
The Belgrade underground laboratory consists of two interconnected spaces, a
ground level laboratory and a shallow underground one, at 25 meters of water
equivalent. The laboratory hosts a ...low-background gamma spectroscopy system
and cosmic-ray muon detectors. With the recently adopted digital data
acquisition system it is possible to simultaneously study independent
operations of the two detector systems, as well as processes induced by
cosmic-ray muons in germanium spectrometers. Characteristics and potentials
of the present experimental setup, together with some preliminary results
for the flux of fast neutrons and stopped muons, are reported here.
Beogradska laboratorija sastoji se od dva laboratorijska prostora, jednog na
povrsini i jednog podzemnog, na dubini od 25 metara vodenog ekvivalenta.
Detaljno su opisani i ilustrovani potencijali ovih laboratorija za merenje
niskih aktivnosti i za kontinuirano merenje mionske i elektromagnetne
komponente kosmickog zracenja, kao i za studije procesa koje ova zracenja
indukuju u germanijumskim spektrometrima smestenim u niskofonskim podzemnim
laboratorijama. Sva ova merenja se izvode simultano, novim sistemom za
digitalnu spektroskopiju, a podaci se zapisuju dogadjaj po dogadjaj, i
analiziraju posle zavrsenih merenja. Takodje su prikazani preliminarni
rezultati koji su u fazi testiranja opreme dobijeni za fluks brzih neutrona i
zaustavljenih miona u povrsinskoj i u podzemnoj laboratoriji.
PR Projekat Ministarstva nauke Republike Srbije, br. 171002
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