scholarly journals Spectroscopic Study of Cytosine Methylation Effect on Thermodynamics of DNA Duplex Containing CpG Motif

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Václav Římal ◽  
Ondřej Socha ◽  
Josef Štěpánek ◽  
Helena Štěpánková
Keyword(s):  
Cytosine Methylation ◽  
Accurate Determination ◽  
Joint Analysis ◽  
Dna Duplexes ◽  
Temperature Dependences ◽  
Scattering Spectra ◽  
Enthalpy And Entropy ◽  
Cpg Motif ◽  
Raman Scattering Spectra ◽  
Duplex Formation

Effect of cytosine methylation on DNA duplexes was studied by using a model system of three self-complementary DNA octamers containing central CpG motif surrounded by a couple of AT base pairs, CAACGTTG, CATCGATG, and CTTCGAAG, and their analogues with the central cytosine methylated at C5 position. Temperature dependences of1H NMR, UV absorption, and Raman scattering spectra measured for aqueous solutions at concentrations of different orders of magnitude were subjected to a joint analysis that allowed an accurate determination of the enthalpy and entropy of duplex formation. It was revealed that the changes of the enthalpy and entropy contributions are strongly dependent on the base composition in the vicinity of the CpG motif.

scholarly journals Investigations of LiNb1−xTaxO3 Nanopowders Obtained with Mechanochemical Method

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 755
Author(s):  
Leonid Vasylechko ◽  
Volodymyr Sydorchuk ◽  
Andrey Lakhnik ◽  
Yuriy Suhak ◽  
Damian Wlodarczyk ◽  
...  
Keyword(s):  
Single Phase ◽  
Structural Parameters ◽  
High Energy ◽  
Optimal Parameters ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Dependences ◽  
Scattering Spectra ◽  
Energy Ball ◽  
Raman Scattering Spectra

Nanocrystalline compounds LiNb1−xTaxO3 of various compositions (x = 0, 0.25, 0.5, 0.75, 1) were synthesized by high-energy ball milling of the initial materials (Li2CO3, Nb2O5, Ta2O5) and subsequent high-temperature annealing of the resulting powders. Data on the phase composition of the nanopowders were obtained by X-ray diffraction methods, and the dependence of the structural parameters of LiNb1−xTaxO3 compounds on the value of x was established. As a result of the experiments, the optimal parameters of the milling and annealing runs were determined, which made it possible to obtain single-phase compounds. The Raman scattering spectra of LiNb1−xTaxO3 compounds (x = 0, 0.25, 0.5, 0.75, 1) have been investigated. Preliminary experiments have been carried out to study the temperature dependences of their electrical conductivity.

scholarly journals Излучение света гетероструктурой CdMnTe/CdMgTe с узкими квантовыми ямами

2019 ◽  
Vol 61 (8) ◽  
pp. 1523
Author(s):  
В.Ф. Агекян ◽  
Е.В. Борисов ◽  
А.Ю. Серов ◽  
Н.Г. Философов ◽  
G. Karczewski
Keyword(s):  
Optical Properties ◽  
Quantum Wells ◽  
Barrier Layer ◽  
Integral Intensity ◽  
Manganese Ions ◽  
Excitation Spectra ◽  
Intracenter Luminescence ◽  
Temperature Dependences ◽  
Scattering Spectra ◽  
Raman Scattering Spectra

AbstractThe optical properties of the Cd_0.4Mn_0.4Te/Cd_0.5Mg_0.5Te heterostructure with quantum wells of 7 monolayers in thickness are studied. The temperature dependences of the integral intensity of luminescence of the barrier layer and quantum well and intracenter luminescence of manganese ions are determined, and the luminescence excitation spectra are measured. Numerous components corresponding to LO phonons of the CdTe, MgTe, and MnTe types are observed in the Raman scattering spectra.

Crystallization of Amorphous Silicon Thin Films by Microwave Heating

2014 ◽  
Vol 1666 ◽  
Author(s):  
Tomohiko Nakamura ◽  
Shinya Yoshidomi ◽  
Masahiko Hasumi ◽  
Toshiyuki Sameshima ◽  
Tomohisa Mizuno
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Amorphous Silicon ◽  
Microwave Heating ◽  
Volume Ratio ◽  
Heated Sample ◽  
Silicon Thin Films ◽  
Scattering Spectra ◽  
Raman Scattering Spectra ◽  
Si Films

ABSTRACTWe report crystallization of amorphous silicon (a-Si) thin films and improvement of thin film transistors (TFTs) characteristics using 2.45 GHz microwave heating assisted with carbon powders. Undoped 50-nm-thick a-Si films were formed on quartz substrates and heated by microwave irradiation for 2, 3, and 4 min. Raman scattering spectra revealed that the crystalline volume ratio increased to 0.42 for the 4-min heated sample. The dark and photo electrical conductivities measured by Air mass 1.5 at 100 mW/cm2 were 2.6x10-6 and 5.2x10-6 S/cm in the case of 4-min microwave heating followed by 1.3x106-Pa-H2O vapor heat treatment at 260°C for 3 h. N channel polycrystalline silicon TFTs characteristics were improved by the combination of microwave heating with high-pressure H2O vapor heat treatment. The threshold voltage decreased from 5.3 to 4.2 V and the effective carrier mobility increased from 18 to 25 cm2/Vs.

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