scholarly journals Anticancer Drug Impact on DNA – A Study by Neutron Spectrocopy, Synchrotron-based FTIR and EXAFS

2018 ◽  
Author(s):  
Ana L.M. Batista de Carvalho ◽  
Adriana P. Mamede ◽  
Asha Dopplapudi ◽  
Victoria Garcia Sakai ◽  
James Doherty ◽  
...  
Keyword(s):  
Experimental Approach ◽  
Simultaneous Detection ◽  
Local Environment ◽  
Elastic Neutron ◽  
Pharmacodynamic Profile ◽  
Infrared Measurements ◽  
Mediate Cytotoxicity ◽  
Enhanced Mobility ◽  
X Ray Absorption ◽  
Dynamical Information

ABSTRACTA complementary structural and dynamical information on drug-DNA interplay has been achieved at a molecular level, for Pt/Pd-drugs, allowing a better understanding of their pharmacodynamic profile. The interaction of two cisplatin-like dinuclear Pt(II) and Pd(II) complexes with DNA was studied through a multidisciplinary experimental approach, using quasi-elastic neutron scattering (QENS) techniques coupled to synchrotron-based extended X-ray absorption fine structure (SR-EXAFS) and Fourier-Transform Infrared Spectroscopy-Attenuated Total Reflectance (SR-FTIR-ATR). The drug impact on DNA’s dynamical profile, via its hydration layer, was provided by QENS, a drug-triggered enhanced mobility having been revealed. Additionally, an onset of anharmonicity was detected for dehydrated DNA, at room temperature. Far- and mid-infrared measurements allowed the first simultaneous detection of the drugs and its primary pharmacological target, as well as the drug-prompted changes in DNA’s conformation that mediate cytotoxicity in DNA extracted from drug-exposed human triple negative breast cancer cells (MDA-MB-231), a low prognosis type of cancer. The local environment of the absorbing Pd(II) and Pt(II) centers in the drugs’ adducts with adenine, guanine and glutathione was attained by EXAFS.

Titanium environment in TiO2–BaO–ZnO–B2O3 glasses by x-ray absorption spectroscopy

2000 ◽  
Vol 15 (3) ◽  
pp. 793-797 ◽  
Author(s):  
N. Watanabe ◽  
A. Y. Ramos ◽  
M. C. M. Alves ◽  
H. Tolentino ◽  
O. L. Alves ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Local Environment ◽  
Titanium Content ◽  
Optical Performance ◽  
X Ray ◽  
X Ray Absorption

The local environment of titanium in glasses of the system TiO2–BaO–ZnO–B2O3 was studied by x-ray absorption spectroscopy. In all glasses, for TiO2 content varying from 35 to 49 mol%, the titanium atoms are mainly fourfold coordinated network formers. For the glass with the highest titanium content, about 20% of the titanium enters into a sixfold environment, indicating the presence of precrystalline nuclei. These nuclei are responsible for the decrease of the optical performance of the glass above threshold titanium content, prior to any observable crystallization.

scholarly journals Preliminary investigation of chlorine speciation in zirconolite glass-ceramics for plutonium residues by analysis of Cl K-edge XANES

MRS Advances ◽  
2019 ◽  
Vol 5 (1-2) ◽  
pp. 37-43
Author(s):  
Amber R. Mason ◽  
Stephanie M. Thornber ◽  
Martin C. Stennett ◽  
Laura J. Gardner ◽  
Dirk Lützenkirchen-Hecht ◽  
...  
Keyword(s):  
Chemical Shift ◽  
Absorption Edge ◽  
Glass Ceramic ◽  
Glass Phase ◽  
Preliminary Investigation ◽  
Glass Ceramics ◽  
Local Environment ◽  
Aluminosilicate Glass ◽  
X Ray ◽  
X Ray Absorption

ABSTRACTA zirconolite glass-ceramic material is a candidate wasteform for immobilisation of chlorine contaminated plutonium residues, in which plutonium and chlorine are partitioned to the zirconolite and aluminosilicate glass phase, respectively. A preliminary investigation of chlorine speciation was undertaken by analysis of Cl K-edge X-ray Absorption Near Edge Spectroscopy (XANES), to understand the incorporation mechanism. Cl was found to be speciated as the Cl- anion within the glass phase, according to the characteristic chemical shift of the X-ray absorption edge. By comparison with Cl K-edge XANES data acquired from reference compounds, the local environment of the Cl- anion is most closely approximated by the mineral marialite, in which Cl is co-ordinate to 4 x Na and/or Ca atoms.

Local structure and defects in ultrahigh-temperature materials of borosilicon carbonitride

2008 ◽  
Vol 23 (6) ◽  
pp. 1642-1646 ◽  
Author(s):  
Kazuhiro Yamamoto ◽  
Naoya Tsuganezawa ◽  
Shin-ichi Makimura ◽  
Daigo Sawa ◽  
Shin-ichi Nakahigashi ◽  
...  
Keyword(s):  
Structural Changes ◽  
Hexagonal Boron Nitride ◽  
X Ray Diffraction ◽  
X Ray ◽  
Relative Peak Intensity ◽  
Resistance To Oxidation ◽  
Infrared Measurements ◽  
Void Defects ◽  
Ultrahigh Temperature ◽  
X Ray Absorption

We have investigated structural changes of amorphous borosilicon carbonitride materials with atomic ratios of B/Si/C of 2/3/6 and 4/3/6 calcined at several temperatures. The boron K-edge x-ray absorption spectra showed that the structures of both hexagonal boron nitride ([BN3] unit) with nitrogen-void defects ([BN2] and [BN1] units) and boron oxide existed in the samples, and the relative peak intensity due to the [BN3] unit became stronger by increasing the calcined temperature. It is thought that the well-developed B–N chain and the borosilicate glass coating lead to the high resistance to oxidation at high temperature. X-ray diffraction and infrared measurements followed the x-ray absorption near-edge spectroscopy findings.

Determining the Ratio of the Precipitated versus Substituted Arsenic by XAFS and SIMS in Heavy Dose Arsenic Implants in Silicon

2001 ◽  
Vol 669 ◽  
Author(s):  
M. A. Sahiner ◽  
S. W. Novak ◽  
J. C. Woicik ◽  
J. Liu ◽  
V. Krishnamoorty
Keyword(s):  
Solid Solubility ◽  
Amorphous Materials ◽  
Nearest Neighbor ◽  
Secondary Ion Mass Spectrometry ◽  
Local Environment ◽  
Coordination Numbers ◽  
Annealing Conditions ◽  
X Ray Absorption ◽  
Secondary Ion ◽  
Nearest Neighbor Distances

ABSTRACTDoping silicon with arsenic by ion implantation above the solid solubility level leads to As clusters and/or precipitates in the form of monoclinic SiAs causing electrical deactivation of the dopant. Information on the local structure around the As atom, and the As concentration depth profiles is important for the implantation and annealing process in order to reduce the precipitated As and maximize the electrically activated As. In this study, we determined the local As structure and the precipitated versus substituted As for As implants in CZ (001) Si wafers, with implant energies between 20 keV and 100 keV, and implant doses ranging from 1 × 1015/cm2 to 1 × 1018/cm2. The samples were subjected to different thermal annealing conditions. We used secondary ion mass spectrometry (SIMS) and UT- MARLOWE simulations to determine the region where the As-concentration is above the solid solubility level. By x-ray absorption fine structure spectroscopy (XAFS), we probed the structure of the local environment around As. XAFS being capable of probing the short-range order in crystalline and amorphous materials provides information on the number, distance and chemical identity of the neighbors of the main absorbing atom. Using Fourier analysis, the coordination numbers (N) and the nearest-neighbor distances (R) to As atoms in the first shell were extracted from the XAFS data. When As precipitates as monoclinic SiAs, the nearest-neighbor distances and coordination numbers are ∼2.37 Å and ∼3, as opposed to ∼2.40 Å and ∼4 when As is substitutional. Based on this information, the critical implant dose where the precipitation/clustering of As starts, and the ratio of the substitutional versus cluster/precipitate form As in the samples were determined.

Extended x-ray absorption fine structure study of incorporation of Bi and Pb atoms into the crystal structure of Ba4.5Nd9Ti18O54

1997 ◽  
Vol 12 (3) ◽  
pp. 799-804 ◽  
Author(s):  
M. Valant ◽  
I. Arčon ◽  
D. Suvorov ◽  
A. Kodre ◽  
T. Negas ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Fine Structure ◽  
Local Environment ◽  
Structure Study ◽  
X Ray ◽  
Absorption Fine ◽  
Exafs Study ◽  
X Ray Absorption

In the extended x-ray absorption fine structure (EXAFS) study of the local environment of Bi3+ and Pb2+ ions incorporated in Ba4.5Nd9Ti18O54, actual sites of Bi- and Pb-incorporation are determined. Evidence is given that dopant ions are not distributed randomly on all theoretically possible sites; Bi3+ selectively enters one out of three possible channels, corresponding to the sites x = 0.9484, y = 0.2500, z = 0.2939, and/or x = 0.0455, y = 0.2500, z = 0.6928 previously occupied by Nd3+, while Pb2+ selectively enters site x = 0.4940, y = 0.2500, and z = 0.4993 previously shared by Ba2+ and Nd3+.

scholarly journals Correction: Investigation of the local environment of iodate in hydroxyapatite by combination of X-ray absorption spectroscopy and DFT modeling

RSC Advances ◽  
2014 ◽  
Vol 4 (81) ◽  
pp. 43166-43166
Author(s):  
Danielle Laurencin ◽  
Delphine Vantelon ◽  
Valérie Briois ◽  
Christel Gervais ◽  
Antoine Coulon ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Local Environment ◽  
X Ray ◽  
Dft Modeling ◽  
X Ray Absorption
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