Excitation functions of proton induced nuclear reactions on natW up to 40 MeV

Excitation functions for the production of the 181,182m,182g,183,184g,186Re and 183,184Ta radionuclides from proton bombardment on natural tungsten were measured using the stacked-foil activation technique for the proton energies up to 40 MeV. A new data set has been given for the formation of the investigated radionuclides. Results are in good agreement with the earlier reported experimental data and theoretical calculations based on the ALICE-IPPE code. The thick target integral yields were also deduced from the measured excitation functions. The deduced yield values were compared with the directly measured thick target yield (TTY), and found acceptable agreement. The investigated radionuclide 186Re has remarkable applications in the field of nuclear medicine, whereas the data of 183,184gRe and 183Ta have potential applications in thin layer activation analysis and biomedical tracer studies, respectively.Comment: 21papes, 14 figure

Synthesis, characterization of cesium and cobalt substituted wells–Dawson heteropolyoxotungstates salts and their photocatalytic applications

Heteropoly compounds in the solid state are ionic crystals (sometimes amorphous) consisting of large polyanions, cations, water of crystallization, and other molecules. Heteropolyacids (HPAs) have several advantages as catalysts. On the one hand, they have a very strong Brønsted acidity, especially the cobalt and cesium salts; on the other hand they are exhibiting fast reversible multielectron redox transformations under mild conditions. The cobalt and cesium salts of wells–Dawson HPAs were synthesized and characterized using elemental analysis and spectroscopic techniques (31P-NMR, FT-IR). The wells–Dawson anions possess the ability to accept or release electrons through an external potential or upon exposure to UV radiation (photochemical reactions). The catalytic tests of these salts were investigated on phenol degradation where the UV photodegradation of acidified aqueous solutions (pH = 2) were studied in a batch photoreactor under ambient temperature and continuous circulation of phenol solution. The results reveal high catalytic activity for two HPAs, the best catalyst is the salt of cesium; where the presence of cesium improves significantly both the photcatalytic activity and the selectivity to oxalic acid

Photocatalytic degradation of pesticides in presence of 12-tungstophosphoric acid and titanium dioxide: Comparison of the degradation mechanism

In this dissertation the photocatalytic degradation of organic pollutants with different structures, under UV and near visible light in the presence of the polyoxometallate Η3PW12O40, has been studied and compared with the photodegradation with TiO2, in order to elucidate the photooxidation mechanism in the presence of both photocatalysts. The organic pollutants studied were: fenitrothion, atrazine, 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chlorophenol.Fenitrothion is effectively degraded in the presence of both photocatalysts, leading to the formation of CO2 and inorganic anions (PO43-, SO42-, NO2-, NO3-) as final products. Various intermediates, identical in the presence of both photocatalysts, have been detected and identified using High Performance Liquid Chromatography (HPLC) and Gas Chromatography-Mass Spectrometry (GC-MS) techniques. The intermediates detected prior to mineralization were: 3-methyl-4-nitrophenol, fenitrooxon, formylfenitrothion, 2-methyl-1,4-benzoquinone, 2-methyl-hydroquinone, 3-methyl-4-nitroanisole, and O,O,S-trimethyl-phosphorothioate. The organic pollutant 2,4-D is completely degraded to CO2 and Cl- ions in the presence of Η3PW12O40 and TiO2.The intermediates detected prior to mineralization of 2,4-D in presence of TiO2 were: 2,4-dichlorophenol, 2,4-dichlorophenol formate, 4,6-dichloro-resorcinol and chloro-hydroquinone, whereas in presence of Η3PW12O40 the same intermediates as in case with TiO2 and additional two more hydroxylated intermediates namely 3,5-dichloro-catechol and 4-chlorocatechol have been identified.Analysis for some intermediates in case of 2,4-D supports the different photodegradation mode for TiO2 versus Η3PW12O40.4-Chlorophenol is mineralized to CO2 and Cl- ions in the presence of Η3PW12O40 and TiO2. Using Gas Chromatography-Mass Spectrometry (GC-MS), the intermediates 4-chlorocatechol and hydroquinone have been identified for the system 4-chlorophenol/Η3PW12O40, whereas no hydroquinone and only traces of 4-chlorocatechol have been detected for the system 4-chlorophenol/ TiO2.In order to shed more light into the photooxidation mechanism of the organic pollutants fenitrothion, atrazine, 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chlorophenol in presence of Η3PW12O40 and TiO2, i.e., whether it is exercised via HO. radicals or holes or both, parallel experiments have been conducted in presence of HO. radical scavengers, potassium bromide, isopropyl alcοhol, tertiary butyl alcohol and acetone.The organic pollutants under investigation can be grouped in two categories according to the results obtained from the experiments with the HO. radical scavengers.a) fenitrothion, atrazine: whose photooxidation mode by Η3PW12O40 and TiO2, is similar. The main oxidant is HO. Radical. b) 2,4-D and 4-chlorophenol: whose photooxidation mode by Η3PW12O40 is different than that of TiO2. Η3PW12O40 operates essentially via HO. radicals, whereas TiO2 operates mainly via holes and to a lesser extent HO. radicals. The results obtained from the experiments of the scavengers and the analysis of the intermediates support the evidence, that the photodegradation mechanism of organic pollutants is different in presence of Η3PW12O40 and TiO2.Στην παρούσα Διδακτορική Διατριβή μελετήθηκε η φωτοκαταλυτική αποικοδόμηση των οργανικών ενώσεων (ρύπων), φενιτροθειόν, ατραζίνη, 2,4- διχλωροφαινοξυοξικό οξύ (2,4-D) και 4-χλωροφαινόλη με ακτινοβολία στο υπεριώδες εγγύς-ορατό φως, παρουσία των φωτοκαταλυτών H3PW12O40 και TiO2, με σκοπό την διερεύνηση του μηχανισμού αποικοδόμησης και την σύγκριση μεταξύ των δύο φωτοκαταλυτών. Το φενιτροθειόν αποικοδομείται πλήρως παρουσία των δύο φωτοκαταλυτών δίνοντας ως τελικά προιόντα CO2 και ανόργανα ιόντα (PO43-, SO42-, NO2-, NO3-).Πλήθος ενδιαμέσων προιόντων, κοινών για τους δυο φωτοκαταλύτες, προσδιορίσθηκαν χρησιμοποιώντας υγρή χρωματογραφία υψηλής απόδοσης (HPLC) και αέρια χρωματογραφία-φασματομετρία μάζας (GC-MS). Τα ενδιάμεσα τα οποία ταυτοποιήθηκαν πριν την πλήρη αποικοδόμηση του φενιτροθειόν είναι τα εξής: φενιτροοξόν, φορμυλφενιτροθειόν, 3-μέθυλ-4-νιτροφαινόλη, 3-μέθυλ -4-νιτροανισόλη, 2-μέθυλ-υδροκινόνη, 2-μέθυλ-l,4-βενζοκινόνη και Ο,Ο,S-τριμέθυλο-φωσφoροθειοϊκός εστέραςΗ οργανική ένωση 2,4-D αποικοδομείται πλήρως σε διοξείδιο του άνθρακα και ιόντα Cl- παρουσία H3PW12O40 και TiO2. Τα ενδιάμεσα που ανιχνεύθηκαν κατά την φωτοκαταλυτική αποικοδόμηση του 2,4-D με TiO2 είναι τα εξής: 2,4-διχλωροφαινόλη, φορμικός εστέρας της 2,4-διχλωροφαινόλης, 4,6-διχλωρο-ρεσορκινόλη και χλωρο-υδροκινόνη, ενώ με H3PW12O40 ανιχνεύθηκαν, εκτός των ιδίων ενδιαμέσων με αυτά του TiO2, τα ενδιάμεσα: 3,5-διχλωρο-κατεχόλη και 4-χλωροκατεχόλη.Το οργανικό υπόστρωμα 4-χλωροφαινόλη παρουσία H3PW12O40 και TiO2, αποικοδομείται πλήρως σε διοξείδιο του άνθρακα και ιόντα Cl-. Με αέρια χρωματογραφία-φασματομετρία μάζας ταυτοποιήθηκαν τα ενδιάμεσα υδροκινόνη και 4-χλωροκατεχόλη κατά την αποικοδόμηση της 4-χλωροφαινόλης παρουσία H3PW12O40, ενώ παρουσία TiO2 ανιχνεύθηκε σε ίχνη μόνο η 4-χλωροκατεχόλη.Προκειμένου να διερευνηθεί ο μηχανισμός φωτοοξείδωσης των οργανικών υποστρωμάτων φενιτροθειόν, ατραζίνης, 2,4-D και 4-χλωροφαινόλης παρουσία H3PW12O40 και TiO2, εάν δηλ. αποικοδομούνται με ρίζες ΗΟ. ή με απ΄ευθείας αντίδραση, έγιναν πειράματα παρουσία δεσμευτών ριζών ΗΟ., όπως βρωμιούχου καλίου, ισοπροπανόλης, τριτοταγούς βουτυλικής αλκοόλης και ακετόνης. Από τα αποτελέσματα των πειραμάτων που έγιναν παρουσία των δεσμευτών ριζών HO. προέκυψε ότι οι οργανικές ενώσεις που μελετήθηκαν μπορούν να καταταγούν σε δύο κατηγορίες: α) φενιτροθειόν, ατραζίνη: για τις οποίες ο τρόπος φωτοοξείδωσης είναι όμοιος και με τους δύο φωτοκαταλύτες, Η3PW12O40 και TiO2. Το κύριο οξειδωτικό είναι οι ρίζες HO.. β) 2,4-D και 4-χλωροφαινόλη: για τις οποίες ο τρόπος φωτοοξείδωσης παρουσία H3PW12O40 είναι διαφορετικός από εκείνον παρουσία TiO2. To Η3PW12O40 λειτουργεί βασικά μέσω ριζών HO., ενώ το TiO2 λειτουργεί κυρίως μέσω οπών h+.Τα αποτελέσματα των πειραμάτων με τους δεσμευτές ριζών HO., καθώς και αυτά των ενδιαμέσων προϊόντων, ενισχύουν την άποψη ότι ο μηχανισμός φωτοαποικοδόμησης των υποστρωμάτων είναι διαφορετικός παρουσία των δύο φωτοκαταλυτών H3PW12O40 και TiO2

Charged particle activation analysis applied to medium Z elements

A comprehensive survey has been made on the application of charged particle activation analysis for the detection of traces of medium Z elements (40 [less than or equal to] Z [less than or equal to] 58, 72, 74) using four different charged particles; protons and deuterons of 20 MeV, helium-3 and helium-4 ions of 40 MeV. The search for the product nuclides was limited to the radiosiotopes with half-lives ranging from 10 minutes to 3 days. Under the experimental conditions used, proton activation was found to provide an optimum compromise between sensitivity and selectivity. The excitation functions for the following high sensitivity proton reactions were measured: Zr(p,xn)[superscript 90]Nb, Mo(p,xn)[superscript 94]Tc, Mo(p,2n)[superscript 99mm]Tc, Pd(p,xn)[superscript104]Ag, Ag(p,n)[superscript 107]Cd, Cd(p,xn)[superscript 109]In, Cd(p,xn)[superscript 110m]In, Cd(p,xn)[superscript 113m]In, Sn(p,xn)[superscript 115]Sb, Sn(p,xn)[superscript 116m]Sb, Sn(p,xn)[superscript 117]Sb, Sn(p,xn)[superscript 118ml]Sb, Te(p,2n)[superscript 121]I, Te(p,xn)[superscript 123]I, Te(p,n)[superscript 128]I, Te(p,n)[superscript 130]I, Cs(p,n)[superscript 133m]Ba . The pertinent ??-ray energies were also redetermined. The feasibility of nondestructive determinations using 11 MeV protons for Zr, Mo, and Cd in high purity glass was investigated. Zirconium can be determined nondestructively and analytical results are presented and discussed. The estimated detection limit for the nondestructive zirconium determination is 0.001 ppm using a 12 [micro]A-hour irradiation

Charged particle activation analysis applied to medium Z elements

A comprehensive survey has been made on the application of charged particle activation analysis for the detection of traces of medium Z elements (40 [less than or equal to] Z [less than or equal to] 58, 72, 74) using four different charged particles; protons and deuterons of 20 MeV, helium-3 and helium-4 ions of 40 MeV. The search for the product nuclides was limited to the radiosiotopes with half-lives ranging from 10 minutes to 3 days. Under the experimental conditions used, proton activation was found to provide an optimum compromise between sensitivity and selectivity. The excitation functions for the following high sensitivity proton reactions were measured: Zr(p,xn)[superscript 90]Nb, Mo(p,xn)[superscript 94]Tc, Mo(p,2n)[superscript 99mm]Tc, Pd(p,xn)[superscript104]Ag, Ag(p,n)[superscript 107]Cd, Cd(p,xn)[superscript 109]In, Cd(p,xn)[superscript 110m]In, Cd(p,xn)[superscript 113m]In, Sn(p,xn)[superscript 115]Sb, Sn(p,xn)[superscript 116m]Sb, Sn(p,xn)[superscript 117]Sb, Sn(p,xn)[superscript 118ml]Sb, Te(p,2n)[superscript 121]I, Te(p,xn)[superscript 123]I, Te(p,n)[superscript 128]I, Te(p,n)[superscript 130]I, Cs(p,n)[superscript 133m]Ba . The pertinent ??-ray energies were also redetermined. The feasibility of nondestructive determinations using 11 MeV protons for Zr, Mo, and Cd in high purity glass was investigated. Zirconium can be determined nondestructively and analytical results are presented and discussed. The estimated detection limit for the nondestructive zirconium determination is 0.001 ppm using a 12 [micro]A-hour irradiation

Vyhodnocení empirických titračních ekvivalentů určitých typů průmyslových povrchově aktivních látek stanovitelných potenciometrickou titrací tetrapenylboritanem sodným

In this study, it has been shown that potenciometric titration using sodium tetraphenylborate as the titrant can be used as a simple and inexpensive method for the determination of some industrial surfactants commonly used in detergents. Examples of determination of some cationic and non-ionic surfactants and related calculations are given.Tato studie ukázala, že potenciometrická titrace používající tetrafenylboritan sodný jako titrant může být použita jako jednoducjá a nenákladná metoda pro stanovení některých průmyslových tenzidů běžně používaných v detergentech. Jsou uvedeny příklady stanovení některých kationtových a neiontových povrchově aktivních látek a související výpočty

Rearrangement of unsaturated cyclic peroxides obtained by photooxygenation of 2,3-dimethylene-7-oxabenzonorbornene and 2,3-dimethylene-1,4-etheno-1,2,3,4-tetrahydronaphthalene

Cobalt(II) tetraphenylporphyrin (CoTPP)-catalyzed rearrangement of peroxide 11 obtained by the photooxygenation of 5 gave a mixture of epoxides 15 (or 16) and 17. However, CoTPP-catalyzed rearrangement of peroxide 20 arising by photooxygenation of 2,3-dimethylene-1,4-etheno-1,2,3,4-tetrahydronaphthalane 6 gave 1,4-etheno-1,2,3,4-tetrahydronaphtho[b]-furan 21. The different behaviour of these endoperoxides 11 and 20 is discussed in terms of ring strain and the degree of the pyramidalization of the C=C bon

Paladyum Komplekslerine Dayalı İyodür-Seçici Karbon Pasta Elektrot Hazırlanması

Dibromo[1,1′-bis(difenilfosfin)ferrosen] paladyum(II) (iyonofor I) ve dikloro[1,1′-bis(difenilfosfin)ferrosen] paladyum(II) (iyonofor II) olarak adlandırılan paladyum komplekslerinin kullanıldığı yeni iyodür-seçici karbon pasta elektrotlar hazırlandı. İyonofor I ve II kullanılarak optimum karbon pasta bileşimiyle hazırlanan elektrotların pH 4,0’da sırasıyla −43,2 ± 0,6 mV/pI ve −43,8 ± 0,6 mV/pI eğimle, 3,5×10−6 M ve 3,7×10−7 M gözlenebilme sınırıyla, 1,0×10−5 − 1,0×10−1 M ve 1,0×10−6 − 1,0×10−1 M derişim aralığında doğrusal cevap verdikleri gözlendi. Önerilen elektrotların kısa cevap sürelerine, 3 aylık ömre, iyi bir tekrarlanabilirlik ve üretilebilirliğe sahip oldukları bulundu. Ayrıca, elektrotlar, iyodür içeren ilaç numunelerinde iyodürün potansiyometrik tayini için indikatör elektrot olarak başarılı bir şekilde kullanıldı