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1
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Synchrotron Radiation: New Trend in X-Ray Mammography

100%
Burattini E.
Acta Physica Polonica A
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1997
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vol. 91
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issue 4
707-713
EN
In order to exploit the peculiar characteristics of synchrotron radiation for X-ray mammography purposes, monochromatic X-ray beams of selected energies from 16 keV to 22 keV have been used for the first time ever to obtain mammograms of surgically removed breast specimens containing cancer nodules. The apparatus devised particularly in view of a possible clinical applications, allowed large breast specimens fixed in space to be exposed to a vertical scanning X-ray beam. The mammograms obtained with synchrotron radiation, compared with those made using a traditional mammographic unit had higher contrast and better resolution demonstrating, in all the cases studied, a high capability to display a large number of structures inside the neoplastic lesions. Thermoluminescent dosimeters were used to determine the doses. The average mean glandular doses, at 17 keV and 18 keV, were 1.56 mGy and 0.84 mGy, respectively, comparable with the value of 1.41 mGy delivered with the conventional grid apparatus.
2
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X-Ray Absorption Near Edge Spectroscopy of Sulfur in Biomolecules: Two Examples from Glutathione and Insulin

51%
Cinque G., Bellisola G., Colombatti M., Burattini E.
Acta Physica Polonica A
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2006
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vol. 109
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issue 3
335-340
EN
Although a minor constituent of cell and tissues, sulfur is an essential element to fulfil a wide range of biological processes, and it is present in the functional groups of many biomolecules that participate to redox reactions in vivo. Cysteine, one of the two S-containing aminoacids present in proteins, contains sulfur in fully reduced form and its thiol group can undergo a range of reactions under physiological conditions. X-ray absorption spectroscopy represents a unique tool to speciate the redox state of sulfur in biomolecules because of the known strong correlation between oxidation state and absorption edge energy shift (over 10 eV). Moreover, a rich X-ray absorption near edge structure is related to the chemical structures of S-containing biomolecules, as well as significant spectral changes due to biochemical action. The formation of a disulfide bond, i.e. a covalent linkage between the S atoms of two cysteine residues, or its reduction were investigated only indirectly in biomolecules. X-ray absorption spectroscopy experiments at the sulfur K-edge were performed at the soft X-ray beamline in Frascati using the wiggler source of the 0.51 GeV storage ring DAΦNE. X-ray absorption near edge structure data were collected to distinguish in situ between S-thiol and disulfide on model protein systems. Such preliminary results confirm this technique as a unique probe of sulfur chemistry in vivo. Quantitative speciation of S-metabolites can be foreseen in biological tissues with no chemical manipulations of the specimen.
3
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Manganese Distribution in CdMnTeSe Crystals. EXAFS Data Analysis

45%
Kisiel A., Łażewski J., Zimnal-Starnawska M., Burattini E., Mycielski A.
Acta Physica Polonica A
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1996
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vol. 90
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issue 5
1032-1034
EN
The extended X-ray absorption fine structure (EXAFS) technique has been used to investigate the first shell coordination in zinc-blende quaternary Cd_{1-x}Mn_{x}Te_{1-y}Se_{y} (0.0 ≤ x ≤ 0.15; 0.0 ≤ y ≤ 0.20) alloys. The experimental data have been collected with the use of synchrotron radiation. All the nearest-neighbour distances have been found as linearly dependent on Se and Mn concentration. For each composition a consistent deviation from full random distribution of Mn atoms around Se and Te atoms was observed. Possible reasons of preferential Mn-Se over Mn-Te pairing were discussed.
4
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X-Ray Absorption Near Edge Structure Analysis of HgMnSe, HgFeSe and HgTeSe

45%
Burattini E., Kisiel A., Markowski R., Dalba G., Giriat W.
Acta Physica Polonica A
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1993
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vol. 83
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issue 1
107-114
EN
Experimental studies of the Se K X-ray absorption edges have been carried out in HgTe_{0.5}Se_{0.5}, Hg_{0.8}Mn_{0.2}Se and Hg_{0.9}Fe_{0.1}Se. A comparison is made for Hg_{0.5}Mn_{0.5}Se and Hg_{0.5}Fe_{0.5}Se theoretical results obtained by the self-consistent, semi-relativistic LMTO method within the LD approximation. Small differences of Se K edge XANES have been shown for HgTeSe and HgSe in contrary to evident differences for HgMnSe and HgFeSe. This behaviour of the absorption Se K edges is related to significant, hybridized contribution of the 3d and 4s Mn or Fe unoccupied states. The maximal contributions of the hybridized bands of the hypothetic zinc-blende MnSe or FeSe were estimated using the virtual crystal model. These maximal contributions are situated at about 6 eV and 17 eV in zinc-blende MnSe and at -0.8 eV and 5.5 eV in zinc-blende FeSe. For HgFeSe apart from the evidence of the strongly localized resonant donor (empty for low Fe concentrations) the complementary hybridized contribution of Fe 3d empty states also situated around the conduction band minimum should be taken into consideration.
5
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The XANES K-Edge Spectra for HgMnSe and HgFeSe

39%
Kisiel A., Oleszkiewicz J., Goniakowski J., Markowski R., Burattini E., Dalba G., Rocca F.
Acta Physica Polonica A
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1991
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vol. 80
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issue 3
373-376
EN
X-ray absorption near-edge structure for Hg_{1-x}Mn_{x}Se and Hg_{1-x}Fe_{x}Se was studied with the use of synchrotron radiation. The self-consistent, semirelativistic LMTO method within the LD approximation was used to calculate electronic band structure and K-edge spectra of these semimagnetic semiconductors. The theoretical results for X-ray absorption spectra were compared with experimental data.
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