Study of Sorption Kinetics of Doxycycline on pH Sensitive Hydrogel-based Graft Copolymers of Chitosan/Arabinogalactan/ Gummiarabic with Vinyl Monomers

Graft copolymers of natural polysaccharides chitosan (Chs), gummi-arabic (GA) and arabinogalactan (AG) were synthesized with N-vinylpyrrolidone (VPr) (4-vinylpyridine and N-vinylpyrrolidone used as comonomers for chitosan grafting), and then pH-sensitive hydrogels were designing by cross-linked them with N,N-methylene-bis-acrylamide. Effective sorption of doxycycline from aqueous solutions with water-swelling gels has been studied experimentally. The effect of gel dose, initial concentration of doxycycline, pH medium and solution ionic strength of the sorption rate and capacity of the antibiotic was systematically studied. The surface and volume absorption kinetics and isotherms of the process have also been investigated. It was found that the max sorption capacity for swellable gels varies between Chs-graft-VPr/4VPAG/graft-VPrGA/graft-VPr. It has been shown that the sorption mechanism is mainly dominated by physical sorption and to some extent hydrogen bonds and electrostatic interactions.

On the importance of field driven single particle processes in short pulse absorption of clusters

Nano-clusters are acclaimed to be very efficient absorbers of intense femto second light due to dominant collective mechanisms. Enhanced near 100% absorption due to collective linear plasma resonance compared to a small fraction of absorption by unclustered gas was an important drive in nano-plasma studies. Contrary to such perception, we show that if the pulse duration is (<100 fs), absorption is same irrespective of whether the systems are condensed to large clusters or not. So long as there are same number of similar ionizable systems in the focal volume, absorption is the same and such absorption can be accounted for by single particle response to the field and collisional ionization of atoms. Short pulse absorption by the single particle response can be comparable to the linear plasma resonance absorption for smaller clusters.

Laser Irradiated Foam Targets: Absorption and Radiative Properties

An experimental campaign to characterize the laser radiation absorption of foam targets and the subsequent emission of radiation from the produced plasma was carried out in the ABC facility of the ENEA Research Center in Frascati (Rome). Different targets have been used: plastic in solid or foam state and aluminum targets. The activated different diagnostics allowed to evaluate the plasma temperature, the density distribution, the fast particle spectrum and the yield of the X-Ray radiation emitted by the plasma for the different targets. These results confirm the foam homogenization action on laser-plasma interaction, mainly attributable to the volume absorption of the laser radiation propagating in such structured materials. These results were compared with simulation absorption models of the laser propagating into a foam target.

Study on Physical and Photoluminescence Properties of Er3+Doped Zinc Barium Tellurite Glasses

Er3+-doped ZnO – BaO – TeO2 glasses with the formula (80-x)TeO2–15ZnO–5BaO–xEr2O3 were fabricated using melt quenching technique. The 5 glass samples with different concentrations of Er2O3 were prepared under atmospheric pressure. The samples were investigated on their properties: density, molar volume, absorption spectra and photoluminescence. Density was increased with an increase in Er3+ content. The molar volume trend is in the opposite way to that of the density. The absorption bands are assigned as absorptions from the 4I15/2 ground state to the 4F7/2, 2H11/2, 4S3/2, 4F9/2, 4I9/2, 4I11/2 and 4I13/2 levels. All absorption bands are increase with increasing content of Er3+. The photoluminescence spectra were measured with 980 nm light pumped by flash lamp. The spectra trends to increase with increasing concentration of the dopant.

Luminescence Characteristics of Li2O3:Gd2O3:B2O3:Dy2O3 Glasses System

Melt quenching technique have been used to prepare the dysprosium-doped lithium-gadolinium borate glasses, which have the composition [60Li2O:10Gd2O3:(30-x) B2O3:xDy2O3] (LGBO:Dy3+), under atmospheric pressure. Some properties: density, molar volume, absorption spectra and photoluminescence of the LGBO:Dy3+ glasses were investigated and discussed. The density of glasses drops to the minimum point at 0.05 mol% and swings after that point. The molar volume of the glasses does not depend on Dy2O3concentration. In absorption spectra for the range of visible to near infrared wavelengths, there are 5 obvious peaks indicating the Dy3+ in glass network. The intensity of each peak at certain wavelength increases with concentration of the Dy2O3. Whereas the excitation spectra show 7 obvious peaks representing the transitions from the ground state 6H15/2to various excited states. The Xenon compact arc lamps were used to measure the emission spectra with 388 nm light. As the result, the LGBO:Dy3+ glass sample with 0.50 mol% of Dy3+ shows the highest intensity in the emission spectra.

Regulation of intramembranous absorption and amniotic fluid volume by constituents in fetal sheep urine

Our objective was to test the hypothesis that fetal urine contains a substance(s) that regulates amniotic fluid volume by altering the rate of intramembranous absorption of amniotic fluid. In late gestation ovine fetuses, amniotic fluid volumes, urine, and lung liquid production rates, swallowed volumes and intramembranous volume and solute absorption rates were measured over 2-day periods under control conditions and when urine was removed and continuously replaced at an equal rate with exogenous fluid. Intramembranous volume absorption rate decreased by 40% when urine was replaced with lactated Ringer solution or lactated Ringer solution diluted 50% with water. Amniotic fluid volume doubled under both conditions. Analysis of the intramembranous sodium and chloride fluxes suggests that the active but not passive component of intramembranous volume absorption was altered by urine replacement, whereas both active and passive components of solute fluxes were altered. We conclude that fetal urine contains an unidentified substance(s) that stimulates active intramembranous transport of amniotic fluid across the amnion into the underlying fetal vasculature and thereby functions as a regulator of amniotic fluid volume.