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Title: Identifikacija, porazdelitev in vezavne oblike železa v rižu (Oryza sativa L.) z rentgensko absorpcijsko in emisijsko mikro-spektroskopijo Authors: ID Arčon, Iztok (Mentor) More about this mentor... ID Šuc, Bojan (Author) Files: Bojan_Suc.pdf (2,98 MB) MD5: 2547A2DFD6713F5394D4D4B84928FA1E   Language: Slovenian Work type: Undergraduate thesis Typology: 2.11 - Undergraduate Thesis Organization: FZO - Faculty of Environmental Sciences Abstract: V diplomskem delu smo raziskali vezavne oblike železa v različnih delih korenin riža s kombinacijo rentgenske absorpcijske spektroskopije in mikroskopije z metodo mikro-XANES. S tem smo želeli izboljšati razumevanje vnosa železovih spojin v rastline riža (Oryza sativa L.) na tkivnem nivoju. Rastline riža so bile vzgojene v hidroponskem sistemu z dodanim železom Fe2+ (kot FeSO4). Spektri mikro-XANES na absorpcijskem robu K železa so bili pomerjeni na prečnih rezinah korenin, zamrznjenih v tekočem dušiku, na žarkovni liniji ID21 sinhrotrona ESRF v Grenoblu v fluorescenčnem načinu. Pri analizi spektrov mikro-XANES smo preučili uporabnost metode linearnega kombiniranja referenčnih spektrov XANES železa izmerjenih na nizu referenčnih dvo- in trivalentnih železovih spojin. Rezultati so pokazali, da je možno s to metodo v rastlinskih vzorcih jasno ločiti med dvo- in trivalentnimi železovimi kompleksi in določiti njihov delež z natančnostjo ±1%. Prevladujoča valenca železa v vzorcih korenin je Fe3+. Prepoznavanje in razločevanje različnih železovih kompleksov je manj natančno. Natančnost pri določanju deleža različnih trivalentnih železovih kompleksov je med 10% in 30%. Nekaterih železovih kompleksov s to metodo ni mogoče razločiti med sabo, ker se njihovi spektri XANES premalo razlikujejo. Kot najpogostejše železove komplekse v koreninah riža smo prepoznali Fe2+-fitat med dvovalentnimi spojinami, med trivalentnimi pa: železov oksid/hidroxid Goethit α-FeOOH Fe3+-citrat in Fe3+-fitat. Na natančnost pri razločevanju železovih spojin znatno vplivajo statistični šum in sistematske napake v izmerjenih spektrih mikro-XANES. Rezultati razmerij med dvo- in trivalentnimi železovimi kompleksi v različnih delih korenin kažejo, da se rastline riža zaščitijo pred strupenim toksičnim dvovalentnim železom tako, da ga oksidirajo in tvorijo tako imenovani plak, oziroma oborino, s čimer omejijo vnos dvovalentnega železa. Keywords: Rentgenska absorpcijska spektrometrija, riž, železo, mikro-XANES, metoda linearnega kombiniranja referenčnih spektrov Place of publishing: Nova Gorica Year of publishing: 2016 PID: 20.500.12556/RUNG-2569  COBISS.SI-ID: 4489979  NUK URN: URN:SI:UNG:REP:47WNIO9J Publication date in RUNG: 06.09.2016 Views: 9369 Downloads: 254 Metadata:    Cite this work Plain text BibTeX EndNote XML EndNote/Refer RIS ABNT ACM Ref AMA APA Chicago 17th Author-Date Harvard IEEE ISO 690 MLA Vancouver : Copy citation

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Secondary language

Language:	English
Title:	Identification, distribution and bonding forms of iron in rice (Oryza sativa L.) with micro X-Ray Fluorescence (μ-XRF) and X-Ray Absorption Spectroscopy (XAS)
Abstract:	In this thesis, we studied the binding forms of iron in different parts of rice roots with a combination of X-ray absorption spectroscopy and microscopy (micro-XANES). We wanted to improve the understanding of intake of iron compounds in rice (Oryza sativa L.) plants at the cellular level. Rice plants were grown in a hydroponic system with iron added in the form of Fe2+ (as FeSO4). Micro-XANES spectra at K absorption edge of iron were measured on transverse slices of the root at synchrotron beamline ID21 of ESRF in Grenoble in a fluorescence mode. The roots were frozen in liquid nitrogen. We have examined the usefulness of the LCF (linear combination fitting) method in the analysis of iron K-edge XANES spectra with a set of iron K-edge XANES spectra measured on reference ferrous and ferric compounds. The results showed that with this method it is possible to clearly distinguish between ferrous and ferric complexes in plant samples and to determine their contribution with an accuracy of ± 1%. The predominant valence state of iron in the roots is Fe3+. Accurate speciation of ferric or ferrous iron complexes is less precise. Accuracy in determining the various ferric complexes is between 10% and 30%. Some iron complexes are indistinguishable with this method, because their XANES spectra are too similar. As the most common iron complexes in the roots of rice, we recognize the Fe2+-fitate among ferrous compounds, and iron oxyde/hydroxide α-FeOOH (Goethite), Fe3+-citrate, Fe3+-fitate among ferric compounds. Accuracy in distinguishing iron compounds is significantly affected by statistical noise and systematic errors in the measured micro-XANES spectra.
Keywords:	X-ray absorption spectroscopy, rice, iron, micro–XANES, linear combination fitting (LCF)

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