Improvement possibilities of the I-V characteristics of PIN photodiodes damaged by gamma irradiation

This paper presents the behavior of PIN photodiodes after combined gamma and neutron irradiation. Different types of PIN photodiodes have been exposed first to gamma and then to neutron irradiation. I-V characteristics (current dependence on voltage) of photodiodes have been measured after each of these irradiations. It has been noted that the photocurrent level after the neutron irradiation is higher than before it, which is not consistent with the current theories about the effects of neutron radiation on semiconductors. In order to explain this behavior of the photodiodes, the Monte Carlo simulation of photon transport through the material has been used. It is proposed that a possible cause for current enhancement are defects in semiconductor created by gamma irradiation and effects of neutron irradiation on these defects. The results can be explained by an intercentre transfer of charge between defects in close proximity to each other. The aim of this paper is to investigate the improvement possibilities of the I-V characteristics of PIN photodiodes, and photodetectors in general, damaged by gamma irradiation. [Projekat Ministarstva nauke Republike Srbije, br. 171007

Evalaution of radioiodination of synthesised meta-iodobenzylguanidine catalyzed by in situ generated Cu(i)

Meta-iodobenzylguanidine (m-IBG) is a biogenic amine precursor, noradrenaline analogue, which is actively taken up by tumors. In tracer amounts, [123/131I]-m-IBG is used as a radiopharmaceutical to target normal and malignant tissues of neuroadrenergic origin for diagnostic scintigraphy, and labeled with higher activities of 131I, it is used for therapy of phenochromocytoma and neuroblastoma. The increased clinical therapeutic use of unlabeled m-IBG at doses of up to 40 mg/m2 emphasizes the need for syntheses and an established quality protocol for this substance that relies on verifiable analytical parameters. Evaluation of radioiodination was necessary to obtain higher labeling yield (we achieved over 90% instead no more than 70%), because isotopic exchange labeling of m-IBG with 131I catalyzed by Cu(I) is much more efficient than with conveniently used ammonium sulphate.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Mechanochemically synthesized cobalt-ferrite and starch-coated cobalt-ferrite nanoparticles as efficient adsorbents for hexavalent chromium removal

Cobalt-ferrite (CoFe2O4) and starch-coated CoFe2O4 nanoparticles were prepared by the mechanochemical method and carefully chosen as adsorbents for Cr(VI) removal from wastewater. The kinetic study, adsorption isotherms and influence of pH, contact time and interfering ions were investigated to have deeper insight into adsorbent quality. UV/Vis spectroscopy confirmed that the dominant adsorption mechanism is the electrostatic attraction at lower pH values. The study showed there was no significant change in adsorption efficiency for starch-coated nanoparticles. However, starch as a natural and biocompatible compound can enhance nanoparticles water dispersibility. The advantage of such materials is that saturation time does not exceed 20 minutes. Therefore, the as-prepared and starch-coated CoFe2O4 presents very efficient material for application in the field of water remediation

Mechanochemically synthesized cobalt-ferrite and starch-coated cobalt-ferrite nanoparticles as efficient adsorbents for hexavalent chromium removal

Cobalt-ferrite (CoFe2O4) and starch-coated CoFe2O4 nanoparticles were prepared by the mechanochemical method and carefully chosen as adsorbents for Cr(VI) removal from wastewater. The kinetic study, adsorption isotherms and influence of pH, contact time and interfering ions were investigated to have deeper insight into adsorbent quality. UV/Vis spectroscopy confirmed that the dominant adsorption mechanism is the electrostatic attraction at lower pH values. The study showed there was no significant change in adsorption efficiency for starch-coated nanoparticles. However, starch as a natural and biocompatible compound can enhance nanoparticles water dispersibility. The advantage of such materials is that saturation time does not exceed 20 minutes. Therefore, the as-prepared and starch-coated CoFe2O4 presents very efficient material for application in the field of water remediation

Spectral analysis of external magnetic field influence on magnetic oxide nano-particles in ferrofluid

Light transmitting measurements of white light and laser beam propagating through FeFe2O4, CoFe2O4 and MgFe2O4 nanoparticles coated with starch, citric and oleic acid, under the influence of an external magnetic field in the range of 30-400 mT, were presented. The unexpected and unusually large changes of transmitted light occurred. This can be explained by the model based on ordering of magnetic moments of nano-particles along the lines of magnetic field into magnetic chains and organization of magnetic chains into spatial structure - a quasi-lattice. Under the influence of external magnetic field, a precipitation of all studied samples was obtained. To the best of our knowledge, the field-induced precipitation effect of ferrites in ferrofluid was not analysed so far and its significance and influence on the further laser treatment of patients previously exposed to ferrite-based MRI agents is not well recognized. This should be of great importance, since neglecting of the precipitation effect would lead to inappropriate response when patients are exposed to diagnostic and/or therapy procedures

Composite hydrogels obtained from extracts of Porphyridium purpureum and alginate

Hydrogels play a significant role in the food industry as three-dimensional polymer networks. Hydrogels have found extensive use not only in the production of traditional food products but also in designing carriers for bioactive components. Developing hydrogels for food applications prioritizes the use of natural ingredients and simple production methods. Extracts from the red microalgae Porphyridium purpureum contain sulphated polysaccharides and vibrantly coloured phycobiliproteins (PBPs), notably B-Phycoerythrin. This makes Porphyridium purpureum an excellent starting point for developing food-based hydrogels with strong bioactive properties. This work aims to develop and characterize the hydrogels from water extracts of Porphyridium purpureum. In order to achieve that, we used the gelling property of the extract under acidic conditions at pH 2.0. Two types of hydrogels based on this algal extract were compared. The first is formed solely in an acidic environment, while the second is formed by adding alginate at the same pH in the presence of calcium ions. The mechanical properties of both hydrogels were determined by frequency sweep measurements using a rheometer with applied plane/plane geometry. Rheological measurements showed that adding alginate significantly increases the mechanical properties and elasticity of the hydrogel. Confocal microscopy demonstrated stronger fluorescence of PBPs in the gel without alginate. Furthermore, the distribution of different PBPs within the gel network is more uniform without alginate. The digestibility of the hydrogels was evaluated using an in vitro static digestion model. Although both hydrogels were confirmed to be digestible, the hydrogel without adding alginate showed higher digestibility. Antioxidant assays, ABTS and a reducing power test showed that bioaccessible peptides after digestion of both hydrogels possess antioxidant activity, with those obtained without alginate having a higher activity. Overall, this research provides a simple and effective approach for developing coloured hydrogels with attractive appearance, good bioaccessibility and notable bioactive properties

Degradation behaviour of PCL/PEO/PCL and PCL/PEO block copolymers under controlled hydrolytic, enzymatic and composting conditions

Short-term hydrolytic and enzymatic degradation of poly(epsilon-caprolactone) (PCL), one series of triblock (PCL/PEO/PCL) and the other of diblock (PCL/PEO) copolymers, with a low content of hydrophilic PEO segments is presented. The effect of the introduction of PEO as the central or lateral segment in the PCL chain on copolymer hydrolysis and biodegradation properties was investigated. FUR results revealed higher hydrolytic degradation susceptibility of diblock copolymers due to a higher hydrophilicity compared to PCL and triblock copolymers. Enzymatic degradation was tested using cell-free extracts of Pseudomonas aeruginosa PAO1, for two weeks by following the weight loss, changes in surface roughness, and changes in carbonyl and crystallinity index. The results confirmed that all samples underwent enzymatic degradation through surface erosion which was accompanied with a decrease in molecular weights. Diblock copolymers showed significantly higher weight loss and decrease in molecular weight in comparison to PCL itself and triblock copolymers. AFM analysis confirmed significant surface erosion and increase in RMS values. In addition, biodegradation of polymer films was tested in compost model system at 37 degrees C, where an effective degradation of block copolymers was observed

Structural characterization of titanate–ferrite composites

Barium titanate–nickel ferrite, barium titanate–zinc ferrite, and barium titanate–nickel-zinc ferrite composite powders prepared by thermal decomposition method were characterized by Raman spectroscopy, scanning electron microscopy (SEM), and X-Ray powder diffraction (XRPD). Obtained materials consisted of pure perovskite and spinel phases. Scanning electron microscopy analyses revealed that the morphology of investigated samples is not uniform, and aggregation of individual particles is a dominant process in all cases. Raman spectroscopy suggested that in the case of barium titanate–nickel ferrite, the coupling of two phases occurred and the core-shell structure was partially formed, while for barium titanate–zinc ferrite the coupling effect is less pronounced

The analysis of 2,3-dicarboxypropane-1,1-diphosphonic acid-coated magnetite nanoparticles under an external magnetic field and their radiolabeling for possible theranostic applications

The advances in nanotechnology are directed towards the development of new theranostic agents based on magnetic nanoparticles that can be used for both cancer detection and treatment. In this study, 2,3-dicarboxypropane-1,1-diphosphonic acid-coated magnetite nanoparticles (Fe 3 O 4 -DPD MNPs) were evaluated for their theranostic application using different methods. The magnetic hyperthermia efficiency of the Fe 3 O 4 -DPD MNPs was investigated in saline solution with ionic strengths between 0.05 and 1.0 mol dm −3 . For a better understanding of hyperthermia, the behavior of Fe 3 O 4 -DPD MNPs under a non-alternating magnetic field was studied, and the transparency of the sample was measured. Furthermore, the radiotracer method using the radionuclides 99m Tc and 90 Y was applied as a reliable and powerful method for evaluating the in vivo behavior of a nanoprobe; a high radiolabeling yield (>93%), in vitro and in vivo stability of the radiolabeled nanoparticles and high heating effect were observed, thus paving the way for the possible theranostic applications of Fe 3 O 4 -DPD MNPs.This is the peer-reviewed version of the following article:Perić, M.; Radović, M.; Mirković, M. D.; Nikolić, A. S.; Iskrenović, P.; Janković, D.; Vranješ-Đurić, S. The Analysis of 2,3-Dicarboxypropane-1,1-Diphosphonic Acid-Coated Magnetite Nanoparticles under an External Magnetic Field and Their Radiolabeling for Possible Theranostic Applications. New Journal of Chemistry 2019, 43 (15), 5932–5939. [https://doi.org/10.1039/c8nj06478d]

The role of polyphenols, sugars, and cell-wall associated polymers in desiccation tolerance of Ramonda serbica

Resurrection plant Ramonda serbica Panc. survives long desiccation periods and fully recovers metabolic functions already one day upon watering. This study aimed to investigate the role of soluble sugars and polyphenols, as well as cell wallassociated polysaccharides and lignin in desiccation tolerance in R. serbica, an endemic species from the Balkan peninsula. We combined differential transcriptomics and proteomics, the analysis of soluble polyphenolics and sugars, as well as FTIR analysis of the cell wall polymers. Pectin, cellulose, hemicellulose, and xyloglucans were identified as polysaccharide components of the R. serbica cell wall and they decreased upon desiccation. Desiccation provoked cell wall remodelling related to the possible production of H2O2/HO via germin-like proteins and pectin demethylesterification. In addition, desiccation induced carbon recycling from starch to soluble sugar osmolytes, whose content significantly increased in desiccated leaves. These data support the importance of specific sugars and the plasticity of the cell wall as one of the major contributors to desiccation tolerance of resurrection species, contributing to further crop drought tolerance improvement