The mechanisms of radical formation in L-α-alanine

Bugay, A. A.; Onischuk, V. A.; Petrenko, T.L.; Teslenko, V. V.

doi:10.1016/s0969-8043(00)00069-5

Cited by 9 publications

(10 citation statements)

References 5 publications

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“…The R1 radical is characterized by the removal of the amino group (H 2 N) from the alanine molecule (Pauwels et al 2001). At present, it is well established that three radicals are formed in irradiated alanine named R1, R2, and R3 (Sagstuen et al 1997), and several papers were published trying to explain their formation (Pauwels et al 2001;Bugay et al 2000;Lahorte et al 1999;Petrenko 2002;Heydari et al 2002;Sagstuen et al 2004;Talbi et al 2004). Particularly, Lahorte et al (1999) described the process in several steps.…”

Section: Resultsmentioning

confidence: 99%

Sensitivity Comparison of Two L-Alanine Doped Blends to Different Photon Energies

Chen¹,

Ramirez²,

Nicolucci³

et al. 2010

Health Physics

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Blends of L-alanine (85% weight proportion) with KI (10%) and with PbI2 (10%), these last two compounds acting as dopants, and with PVA (5%) acting as binder, were prepared in water at 80 degrees C. A blend of pure L-alanine (95%) with PVA (5%) was also prepared. The three blends were irradiated with photon beams of different energies (120 kV, Co, and 10 MV) to a unique dose of 30 Gy to compare their sensitivities for those three energies. EPR spectra of the three irradiated blends were recorded in a K-Band spectrometer (24 GHz) taking aliquots of about 4 mg for each blend. The energy sensitivity of a blend was defined as the peak-to-peak amplitude of its EPR spectrum central line. For the Co energy (1.25 MeV) the blends presented practically the same sensitivity, indicating that the presence of the dopants does not affect the sensitivity of L-alanine. For 10 MV x-rays, there was an increment (around 10%-20%) in sensitivity for the two L-alanine doped blends compared with the pure L-alanine blend (not doped). In the case of 120 kV x-rays, the blends ala+KI and ala+PbI showed increments of 10 and 20 times more sensitivity than the pure L-alanine blend. It is concluded that the dopants KI and PbI2 produce a great enhancement of the L-alanine sensitivity to low-energy photons. For the same dopant's content (10%) in the blend, PbI2 showed a better performance. Increasing the PbI2 proportion (30%) in the blend allows the detection of radiation dose as low as 10 mGy for 120 kV x-rays. These results encourage the authors to try to enhance the sensitivity of L-alanine even more by increasing the dopant's content in the blend and diminishing the lower limit detection. Application of these L-alanine doped blends in the dosimetry in diagnostic radiology could be possible.

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Section: Resultsmentioning

confidence: 99%

Sensitivity Comparison of Two L-Alanine Doped Blends to Different Photon Energies

Chen¹,

Ramirez²,

Nicolucci³

et al. 2010

Health Physics

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“…The proposed chemical structures of these three radical species have later been carefully analyzed using quantum chemistry modeling, and in each instance, the proposed structures were found to agree well with the available experimental data. These structures were also found to be energetically and mechanistically the most probable products. − …”

Section: Introductionmentioning

confidence: 93%

In Quest of the Alanine R3 Radical: Multivariate EPR Spectral Analyses of X-Irradiated Alanine in the Solid State

et al. 2017

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The amino acid l-α-alanine is the most commonly used material for solid-state electron paramagnetic resonance (EPR) dosimetry, due to the formation of highly stable radicals upon irradiation, with yields proportional to the radiation dose. Two major alanine radical components designated R1 and R2 have previously been uniquely characterized from EPR and electron-nuclear double resonance (ENDOR) studies as well as from quantum chemical calculations. There is also convincing experimental evidence of a third minor radical component R3, and a tentative radical structure has been suggested, even though no well-defined spectral signature has been observed experimentally. In the present study, temperature dependent EPR spectra of X-ray irradiated polycrystalline alanine were analyzed using five multivariate methods in further attempts to understand the composite nature of the alanine dosimeter EPR spectrum. Principal component analysis (PCA), maximum likelihood common factor analysis (MLCFA), independent component analysis (ICA), self-modeling mixture analysis (SMA), and multivariate curve resolution (MCR) were used to extract pure radical spectra and their fractional contributions from the experimental EPR spectra. All methods yielded spectral estimates resembling the established R1 spectrum. Furthermore, SMA and MCR consistently predicted both the established R2 spectrum and the shape of the R3 spectrum. The predicted shape of the R3 spectrum corresponded well with the proposed tentative spectrum derived from spectrum simulations. Thus, results from two independent multivariate data analysis techniques strongly support the previous evidence that three radicals are indeed present in irradiated alanine samples.

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“…Spectroscopic properties and hyperfine constants were determined [14][15][16][17]. Alanine and alanine derivatives have been studied by many workers using EPR spectroscopy [18][19][20]. Alanine is an important role for living organisms [18].…”

Section: Introductionmentioning

confidence: 99%

“…Alanine and alanine derivatives have been studied by many workers using EPR spectroscopy [18][19][20]. Alanine is an important role for living organisms [18]. This paper studies the radicals formed in biologically important samples such as glycine tert-butyl ester hydrochloride 263 (GTBEHCl) and L-α-alanine ethyl ester (LAEE).…”

Section: Introductionmentioning

confidence: 99%

Katı durumdaki glycine tertbutyl ester hydrochloride and L-α-alanin eter ester’de oluşan serbest radikallerin similasyon metodu ile incelenmesi

Osmanoğlu¹

2020

El-Cezeri Fen Ve Mühendislik Dergisi

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The paramagnetic centers formed in glycine tert-butyl ester hydrochloride and L-α-alanine ethyl ester after irradiated was determined using EPR spectroscopy. The EPR spectra of the samples were attributed to the H 2 NĊHCO 2 C(CH 3 ) 3 .HCl and CH 3 ĊHCOCH 2 CH 3 radicals, respectively. The magnetic parameters obtained from the spectra were evaluated. The spectra were seen to be stable for more than 2 months at 300 K. Magnetic parameters and the electronic structure of the paramagnetic centers (radicals) were determined with a simulation method.

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The mechanisms of radical formation in L-α-alanine

Cited by 9 publications

References 5 publications

Sensitivity Comparison of Two L-Alanine Doped Blends to Different Photon Energies

Sensitivity Comparison of Two L-Alanine Doped Blends to Different Photon Energies

In Quest of the Alanine R3 Radical: Multivariate EPR Spectral Analyses of X-Irradiated Alanine in the Solid State

Katı durumdaki glycine tertbutyl ester hydrochloride and L-α-alanin eter ester’de oluşan serbest radikallerin similasyon metodu ile incelenmesi

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