Response of l-alanine and 2-methylalanine minidosimeters for K-Band (24GHz) EPR dosimetry

Chen, F.; Graeff, Carlos Frederico de Oliveira; Baffa, Oswaldo

doi:10.1016/j.nimb.2007.08.097

Cited by 22 publications

(9 citation statements)

References 43 publications

(57 reference statements)

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“…[20][21][22][23] In this context, the utilization of small radiation detectors is required, in order to obtain enough spatial resolution. [24][25][26][27] Because the sensitivity of alanine detectors depends on the amount of free radicals that is produced by the radiation, a reduction in the size of the detector also diminishes its sensitivity. 28 Fortunately, at the same time that alanine is suitable for use in radiation detectors, it accumulates the functions of reducing, capping, and stabilizing agent for the production of silver nanomaterials.…”

Section: 19mentioning

confidence: 99%

Synthesis and characterization of silver/alanine nanocomposites for radiation detection in medical applications: the influence of particle size on the detection properties

et al. 2012

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Silver/alanine nanocomposites with varying mass percentage of silver have been produced. The size of the silver nanoparticles seems to drive the formation of the nanocomposite, yielding a homogeneous dispersion of the silver nanoparticles in the alanine matrix or flocs of silver nanoparticles segregated from the alanine crystals. The alanine crystalline orientation is modified according to the particle size of the silver nanoparticles. Concerning a mass percentage of silver below 0.1%, the nanocomposites are homogeneous, and there is no particle aggregation. As the mass percentage of silver is increased, the system becomes unstable, and there is particle flocculation with subsequent segregation of the alanine crystals. The nanocomposites have been analyzed by transmission electron microscopy (TEM), UV-Vis absorption spectroscopy, X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy and they have been tested as radiation detectors by means of electron spin resonance (ESR) spectroscopy in order to detect the paramagnetic centers created by the radiation. In fact, the sensitivity of the radiation detectors is optimized in the case of systems containing small particles (30 nm) that are well dispersed in the alanine matrix. As the agglomeration increases, particle growth (up to 1.5 mm) and segregation diminish the sensitivity. In conclusion, nanostructured materials can be used for optimization of alanine sensitivity, by taking into account the influence of the particles size of the silver nanoparticles on the detection properties of the alanine radiation detectors, thus contributing to the construction of small-sized detectors.

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Section: 19mentioning

confidence: 99%

Synthesis and characterization of silver/alanine nanocomposites for radiation detection in medical applications: the influence of particle size on the detection properties

et al. 2012

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“…(23). Next we consider possible applications to various materials recently suggested for EPR dosimetry applications, including 2-methylalanine (24)(25)(26)(27). Finally a detailed line-shape analysis of the unsaturated EPR signal of the 2-methylalanine radical is performed as a consistency check of the microwave saturation analysis results.…”

Section: Applicationsmentioning

confidence: 99%

Relaxation-Time Determination from Continuous-Microwave Saturation of EPR Spectra

et al. 2009

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Based on the theories of Portis and of Castner 50 years ago, different continuous-wave measurement procedures for analyzing the microwave saturation power dependence of inhomogeneously broadened EPR lines were developed. Although these procedures have been refined, they still use only a few selected points on the saturation curve. A non-linear least-squares procedure for analyzing the microwave-power dependence of inhomogeneously broadened lines using all data points on a saturation curve has been developed. This procedure provides a simple alternative method to obtain magnetic relaxation data when the more direct pulse-saturation techniques are not available or are less suitable. The latter includes applications of quantitative EPR such as dosimetry. Then microwave saturation data should be obtained under conditions similar to those used in the quantitative measurements, which are usually made on first derivative spectra recorded using continuous-wave spectrometers. Selected applications to benchmark literature data and within the field of EPR dosimetry are discussed. The results obtained illustrate that relaxation times comparable to those yielded by various pulse-saturation EPR techniques can be obtained. It appears as a systematic feature that, whenever the pulse EPR data are fitted using bi-exponential functions, the shortest relaxation times obtained are those that correspond best to those measured using the current continuous-wave saturation method.

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“…The electron paramagnetic resonance (EPR) has been widely used for the identification of irradiation damage centers in many substances including amino acid and their derivatives [5][6][7][8][9][10][11][12][13][14][15]. In previous study, Almanov et.al.…”

Section: Introductionmentioning

confidence: 99%

Identification of free radicals induced by gamma irradiation in amino acid derivatives

Aydin¹

2010

Braz. J. Phys.

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Powders of N-acetyl-L-leucine and N-methyl-L-glutamic acid were gamma irradiated and the free radicals formed were investigated at room temperature by electron paramagnetic resonance technique. The free radicals formed in compounds were attributed to the (CH 3 ) 2Ċ CH 2 CH(NHCOCH 3 )COOH and HOOCCH 2 CH 2Ċ (NHCH 3 )COOH radicals respectively. Both radicals are very stable and we could observe them for five months without almost intensity diminution at room temperature. The g values of the radicals and the hyperfine structure constants of the free electron with nearby protons and 14 N nucleus were determined. The results were found to be in good agreement with the existing literature data.

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Response of l-alanine and 2-methylalanine minidosimeters for K-Band (24GHz) EPR dosimetry

Cited by 22 publications

References 43 publications

Synthesis and characterization of silver/alanine nanocomposites for radiation detection in medical applications: the influence of particle size on the detection properties

Synthesis and characterization of silver/alanine nanocomposites for radiation detection in medical applications: the influence of particle size on the detection properties

Relaxation-Time Determination from Continuous-Microwave Saturation of EPR Spectra

Identification of free radicals induced by gamma irradiation in amino acid derivatives

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