Influence of magnetic field on the reduction of 4,8-diaza-3,6,6,9-tetramethyl undecane-3,8-diene2,10-dione dioxime

The influence of the magnetic field with the magnetic induction up to 1,35T on the reduction of 4,8-diaza-3,6,6,9-tetramethylundecane-3,8-diene-2,10-dione dioxime (DI) in anhydrous protic solvents (anhydrous ethanol and 2-propanol) was defined. As the reductants NaBH4 and KBH4 were usedPhysical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

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

Electrochemical separation of 90-yttrium in the electrochemical 90Sr/90Y generator and its use for radiolabelling of DOTA-conjugated somatostatin analog [DOTA0, Tyr3] octreotate

Radiopharmaceuticals based on 90Y are widely used in the treatment of malignant deseases. In order to meet the requirements for their future application, a 90Sr/90Y generator was developed and 90Y eluted from this locally produced generator was used for the radiolabelling of the DOTA-conjugated somatostatin analog [DOTA0,Tyr3] octreotate and the preparation of [90Y-DOTA0,Tyr3] octreotate (90Y-DOTATATE) for peptide receptore radionuclide therapy. 90Sr/90Y generator was based on the electrochemical separation of 90Y from 90Sr in a two-cycle electrolysis procedure. Three electrode cells were used to perform both electrolyses. In both cycles, working electrodes were kept on constant potential. The pH of the solution was adjusted to 2.7 of the value before the electrolyses. The radionuclidic purity of the 90Y solution was analysed by ITLC and extraction paper chromatography. The labelling of peptide (100 mg DOTATATE) with 90YCl3 was performed at 95°C for 30 minutes. Radiochemical purity was determined by HPLC and chromatographic separation, using a solid SepPak C-18 column. Results obtained confirmed the efficiency of our electrochemical separation technique and quality control methods for 90Y. The achieved efficiency of the 90Sr/90Y generator above 96% of the theoretical value represents a good basis for the further development of this generator. The labelling of the DOTATATE with 90Y exhibited a high efficiency, too: there was less than 1% of 90Y3+in the 90Y-DOTATATE

Oksidacioni procesi pri zagrevanju praha intermetalnog jedinjenja SmCo5

Understanding of the thermal stability of intermetallic SmCo5 powder is essential for designing the working atmosphere in all phases of the technological procedure in the production of sintered SmCo5 magnets to obtain maximal magnetic properties. The thermal stability of the SmCo5 powder with defined chemical composition and particle size was investigated in the interval from 20 to 900*C. It was found by thermogravimetic analysis (TGA) that up to 240*C, the oxidation of SmCo5 does not occur. X-Ray diffraction of the thermogravimetric experimental residue of the SmCo5 powder, heated at 240*C, yielded only the presence of the SmCo5 phase. By X-ray diffraction analysis different crystal forms were identified depending on the maximal heating temperature. The following phases were identified: Sm2O3, Co, CoO, Co3O4 and SmCoO3. According to TG and X-ray results, for each of the investigated temperatures, the corresponding chemical reactions were established. The experimental data from both the thermal and X-ray investigations confirm that the phases of pressing and aligning the SmCo5 powder, in the process of producing sintered SmCo5 magnets, may be performed without a protective atmosphere

Uticaj uslova mlevenja na svojstva intermetalnog jedinjenja SmCo5

The dependence of magnetic properties of sintered magnetic materials, demands the quantification of the milling conditions. In this paper the part of the results of the investigation of the phase of milling of SmCo5 powder in investigated technological procedure for production of sintered SmCo5 magnets are presented. The dependence of particle size of SmCo5 powder and oxygen pick-of milling time has been investigated. By X-ray diffraction the occurrence of magnetic SmCo5 phase has been observed. According to experimental data, the optimal milling time has been established, obtaining the required SmCo5 powder particle size and having the allowed oxygen content.Зависност магнетних својстава синтерованих магнетних материјала захтева квантификацију услова глодања. У овом раду су представљени део резултата испитивања фазе млевења SmCO5 праха у истраженом технолошком поступку за производњу синтерованих SmCo5 магнета. Истражена је зависност величине честица SmCO5 праха и времена млевења при одабирању кисеоника. Дифракцијом Кс-зрака примећена је појава магнетне SmCO5 фазе. Према експерименталним подацима, успостављено је оптимално време млевења, добиjањем потребне величине честица праха SmCO5 и дозвољеним садржајем кисеоника

The influence of protective atmosphere on oxidation of sintered SmCo5 magnetic materials

Understanding of the thermal stability of intermetallic SmCo5 powder is essential for designing the working atmosphere in all phases of the technological procedure in the production of sintered SmCo5 magnets to obtain maximal magnetic properties. The thermal stability of the SmCo5 powder with defined chemical composition and particle size was investigated in the interval from 20 to 900*C. Commercial SmCo5 powder was used in this experiment. The powder was milled in anhydrous toluene in an agate mortar to fine powder of quality used in the production of sintered magnets. All the experiments were carried out with powder of an average particle size of 7.23*m, established by SEM. The thermal stability of the SmCo5 powder in static air atmosphere was investigated by thermogravimetric analysis (TGA) using a DuPont Thermal Analyzer. Investigation of the behavior of SmCo5 powder during heating was carried out using new samples of SmCo5 powder for each of the investigated temperature cycles. It was found by TGA that up to 200*C, the oxidation of SmCo5 was negligible. X-Ray diffraction of the thermogravimetric experimental residue of the SmCo5 powder, heated at 240*C, yielded only the presence of the SmCo5 phase. By X-ray diffraction different crystal forms were identified depending on the maximal heating temperature. The following phases were identified: Sm2O3, Co, CoO, Co3O4 and SmCoO3. According to TG and X-ray results, for each of the investigated temperatures, the corresponding chemical reactions were established. The experimental data from both the thermal and X-ray investigations confirm that the phases of pressing and aligning the SmCo5 powder, in the process of producing sintered SmCo5 magnets, may be performed without a protective atmosphere.Истражена је могућност коришћења вакуума на граници између ниског и високог (10-3-10-4 bar) као заштитне атмосфере у фазама синтеровања и термичке обраде SmCo5 магнета. Испитан је утицај заштитне атмосфере на структурне промене SmCo5 магнета за различите температурне и временске интервале синтеровања, а за константну температуру и у време термичке обраде. Присуство оксидних и других инклузија у било ком делу синтерованих SmCo5 узорака, осим у површинском слоју, није доказано. Сканирајућом електронском микроскопијом (СЕМ), коришћењем Texture Analysis System-a ( TAS´+) мерена је дебљина оскидне зоне. Утврђен је регресиони модел према коме дебљина оксидне зоне расте са квадратом температуре синтеровања, а линеарно са временом синтеровања, за дефинисану температуру термичке обраде

Technetium-99m in Production and Use

Several types of generators have been developed for the production of (99m)Tc. Due to its excelent performances, the chromatographic type, based on the fission-produced (99)Mo sorbed in alumina, is predominant. Technetium-99m is obtained in the form of sodium pertechnetate-(99m)Tc. However, due to the known disadvantages of the production of (n, f)(99)Mo, attempts are made to avoid uranium fission. The technologies based on (n, gamma)(99)Mo (sublimation, extraction, gel) are, with the exception of the gel generator, of limited importance. Certain nuclear reactions in cyclotrons can produce (99)Mo (or directly (99m)Tc) but the obtained results are still not satisfying. Technetium-99m is used in the form of radiopharmaceuticals which are prepared by addition of (99m)Tc-eluate to the inactive components comprised in the cold kits. The chromatographic (n, f)(99)Mo/(99m)Tc generator and several (99m)Tc-radiopharmaceuticals have been developed and are regularly produced in the Vinca Institute of Nuclear Sciences (Laboratory for Radioisotopes)

Modeling of coating optical fibers with polymer-magnetic powder composite coating

A mathematical model of forming a composite coating on optical fiber was established. The model is based on existing mathematical models for coating optical fibers with polymer coating and experimentally defined rheological behavior of the investigated dispersed system. The model was developed for a dispersed system consisting of poly(ethylene-co-vinyl acetate) - EVA in a form of toluene solution and powders of magnetic materials (BaFe12O19 and SmCo5). The influence of the die diameter, diameter of the original optical fiber, concentration of EVA and magnetic powders on the thickness of composite coating was investigated. The model shows good agreement with experimental data.Postavljen je matematički model formiranja kompozitne prevlake na optičkom vlaknu. Model je zasnovan na postojećim matematičkim modelima prevlačenja vlakana polimernom prevlakom i eksperimentalno utvrđenom reološkom ponašanju ispitivanog dispeznog sistema. Model je razvijen za disperzni sistem koji čine rastvor poli(etilen-ko-vinil acetat) EVA u toluenu i prahovi permanentnih magnetnih materijala (BaFe12O19 i SmCo5). Ispitivan je uticaj prečnika dizne, prečnika osnovnog vlakna, koncentarcije EVA i magnetnih prahova na debljinu kompozitne prevlake. Model pokazuje dobro slaganje sa eksperimentalnim podacima

Structural and Luminescence Properties of SrGd2O4 nanocrystalline Phosphor doped with Dy3+ and Sm3+

In this manuscript, down-conversion nanopowders of SrGd2O4 doped with different concentrations of either Dy3+ or Sm3+ ions were examined in detail. All samples were prepared via glycine-assisted combustion method, primarily burned at 500ºC for 1.5 h and additionally calcined at 1000ºC for 2 h, at ambient room temperature. The XRD analysis showed that all samples crystallize as single phase and the orthorhombic lattice SrGd2O4. TEM analysis determined high degree of crystallinity of samples with grain size of approximately 200 nm for Dy3+ doped and 150 nm for Sm3+ doped SrGd2O4. For both samples SAED confirmed that diffraction rings correspond to the hkl plane indices of SrGd2O4, while EDS confirmed presence of Dy in crystal structure. Results of luminescent characterization demonstrated all appropriate emission peaks related to either Dy3+ or Sm3+ dopant ions. Investigation of dopant concentration revealed that the lowest values of both dopants have the most prominent emission peaks, while coordinates obtained from the CIE diagram showed emission shifting with the change of concentration

X-Ray Analysis in the Optimization of the Sintering Process of SmCo5 Magnets

The content of the SmCo5 phase, as the carrier of magnetic properties, was controlled by X-ray diffraction analysis. The content of the SmCo5 phase, as a function of sintering time and temperature, under constant heat treatment conditions, was observed through the intensity of its most significant diffraction peak, which corresponds to the (111) plane. By correlating these parameters with a mathematical treatment, a mutual dependence was established. A regression dependence was obtained that showed that the intensity of the diffraction peak of the (111) plane of the SmCo5 phase depends upon the squares of both the sintering time and temperature, for given heat treatment conditions. It is possible to optimize the sintering conditions by calculating values of sintering time and temperature for which this dependence has its maximum