Реферат: Radiation-induced processes of formation of intrinsic and activator defects in LiF crystals doped with oxides of various metals (Li, W, Fe, Ti) have been investigated. The mechanism of influence of the oxygen impurity on accumulation of electron color centers in the context of notions on self-organization the subradiation defect structure in a form of nanodefect conglomerates in the region of polyvalent cations has been proposed.
Photoinduced charge transfer from titania to surface doping site
Автор(ы): Inerbaev T. M.*(Hoefelmeyer J. D.*Kilin D. S.*
Реферат: We evaluate a theoretical model in which Ru is substituting for Ti at the (100) surface of anatase TiO2. Charge transfer from the photoexcited TiO2 substrate to the catalytic site triggers the photocatalytic event. We perform ab initio computational modeling of the charge transfer dynamics on the interface of the TiO2 nanorod and catalytic site. A slab of TiO2 represents a fragment of the TiO2 nanorod in the anatase phase. Titanium to ruthenium replacement is performed in a way to match the symmetry of the TiO2 substrate. One molecular layer of adsorbed water is taken into consideration to mimic the experimental conditions. It is found that these adsorbed water molecules saturate dangling surface bonds and affect the electronic properties of systems investigated. The modeling is performed by the reduced density matrix method in the basis of Kohn?Sham orbitals. A nanocatalyst modeled through replacement defect contributes energy levels near the bottom of the conduction band of the TiO2 nanostructure. An exciton in the nanorod is dissipating due to interaction with lattice vibrations, treated through nonadiabatic coupling. The electron relaxes to the conduction band edge and then to the Ru site with a faster rate than the hole relaxes to the Ru site. These results are of importance for an optimal design of nanomaterials for photocatalytic water splitting and solar energy harvesting.
Enzyme-free detection of hydrogen peroxide from cerium oxide nanoparticles immobilized on poly(4-vinylpyridine) self-assembledmonolayers
Автор(ы): James D.*Gaynor J. D.*(Karakoti A. S.*Inerbaev T. M.*(Sanghavi Sh.*(Nachimuthu P.*(Shutthanandan V.*Seale S.*(Thevuthasanb S.*
Реферат: A simple enzyme-free spectrophotometric detection of hydrogen peroxide is demonstrated based on its colorimetric reaction with oxygen deficient cerium oxide nanoparticles (CNPs). This colorimetric sensitivity of CNPs towards H2O2 increases significantly with decreasing crystallite size due to an increase in the surface area as well as the concentration of Ce3+ on the surface. The origin of this colorimetric reaction was studied using DFT that suggests the adsorption of peroxide and oxygen molecules on ceria nanoparticles creates new states in the electronic structure leading to transitions absorbing in the visible region of the electromagnetic spectrum. For detection, a single layer of nanoparticles was immobilized on transparent microscopic glass slides using self-assembled monolayers (SAMs) of poly(4-vinylpyridine) (PVP). Cluster-free and uniform immobilization of nanoparticles was confirmed from atomic force microscopy (AFM) and helium ion microscopy (HIM). UV-Visible absorption measurements showed a concentration dependent increase in absorbance from immobilized CNPs that were exposed to increasing concentrations (10-400 ?M) of hydrogen peroxide. The immobilized CNPs can be baked at 80 әC after initial use to regenerate the sensor for reuse. The development of a direct, reusable, enzyme-free and dye-free peroxide sensing technology is possible and can be immediately applied in various areas, including biomedicine and national security.
First-Principles Study of p-n-Doped Silicon Quantum Dots: Charge Transfer, Energy Dissipation, and Time-Resolved Emission
Автор(ы): (Jiangchao Chen*(Schmitz A.*Inerbaev T. M.*(Qingguo Meng*(Kilina S.*(Tretiak S.*(Kilin D. S.*
Реферат: Electron-phonon coupling controls nonradiative relaxation dynamics of the photoexcited electron-hole pair in semiconductor nanostructures. Here the optoelectronic properties for Al- and P-codoped silicon quantum dots (QDs) are calculated by combining time-dependent density matrix methodology and ab initio electronic structure methods. The energy-band landscape of the codoped Si QD is elucidated via time evolution of population density distributions in energy and in coordinate space. Multiple nonradiative relaxation pathways result in a specific charge-separated state, where a hole and an electron are localized on Al and P dopants, respectively. Analysis of the simulated nonradiative decay shows that high-energy photoexcitation relaxes to the band gap edge within 10 ps, forming the final charge-transfer state. We also simulate time-resolved emission spectra of the codoped Si QD that reveals optical and IR emissions below the optical band gap. These emission features are attributed to the intraband transitions introduced by doping.
The Effect of PEGylated Dendrimers on the Catalytic Activity and Stability of Palladium Particles in the Suzuki Reaction
Реферат: Stable dendrimer-coated Pd particles were synthesized using the wet-chemical borohydride reduction method of Pd(II) salts in the presence of low-generation (poly)ethylene glycol-terminated amidoamine-based dendrimers. The identity and structure of the Pd-containing colloids were analyzed by FT-IR spectroscopy, X-ray powder diffraction, thermogravimetric analysis, atom absorption spectroscopy and UV-Vis spectroscopy. Dynamic light scattering experiments have been performed to determine the hydrodynamic diameter of the particles (350-900 nm). The performance of the thus obtained dendrimer-stabilized Pd particles in Suzuki C,C cross-coupling reactions of aryl halides and phenyl boronic acid was examined. Turn over numbers of up to 930 could be achieved. The influence of the dendritic stabilizers on the particle size along with the catalytic performance is presented.
Cirsilineol and cubreuva lactone from Artemisia umbrosa and their biological activity
Автор(ы): Tashenov E. O.*Suleimen E. M.*Dzhalmakhanbetova R. I.*Smagulova F. M.*(Dudkin R. V.*(Gorovoi P. G.*(Ross S. A.*
Объем документа: С. 97-98
МРНТИ: 31.27.21
Ключевые слова: фитохимическое изучение растений*кумарины*модифицированные производные растений*цирсинеолы*сесквитерпеноиды*флаваноиды*биоскрининг*кубрева лактон*
Реферат: The work was performed under the auspices of a grant of the RK MES for budgetary program 055 \"Basic and Applied Research\" on the theme \"Phytochemical Studies of Plants of Kazakhstan and Siberia. Creation of Modified Derivatives Based on Mono- and Sesquiterpenoids, Flavonoids, and Their Bioscreening,\" a grant of the \"Center for International Programs\" (Contract No. 476), and a grant of the RFBR 12-04-01325 (Russia).
Mitochondrial and Y-chromosomal profile of the Kazakh population from East Kazakhstan
Автор(ы): Tarlykov P. V.*Zholdybayeva E. V.*Akilzhanova A. R.*Nurkina Zh. M.*Sabitov Zh. M.*Rahypbekov T. K.*Ramanculov E. M.*
Реферат: Aim To study the genetic relationship of Kazakhs from East Kazakhstan to other Eurasian populations by examining paternal and maternal DNA lineages. Methods Whole blood samples were collected in 2010 from 160 unrelated healthy Kazakhs residing in East Kazakhstan. Genomic DNA was extracted with Wizard genomic DNA Purification Kit. Nucleotide sequence of hypervariable segment I of mitochondrial DNA (mtDNA) was determined and analyzed. Seventeen Y-short tandem repeat (STR) loci were studied in 67 samples with the Amp-FiSTR Y-filer PCR Amplification Kit. In addition, mtDNA data for 2701 individuals and Y-SIR data for 677 individuals were retrieved from the literature for comparison. Results there was a high degree of genetic differentiation on the level of mitochondrial DNA. The majority of maternal lineages belonged to haplogroups common in Central Asia. In contrast, Y-STR data showed very low genetic diversity, with the relative frequency of the predominant haplotype of 0.612. Conclusion The results revealed different migration patterns in the population sample, showing there had been more migration among women. mtDNA genetic diversity in this population was equivalent to that in other Central Asian populations. Genetic evidence suggests the existence of a single paternal founder lineage in the population of East Kazakhstan, which is consistent with verbal genealogical data of the local tribes.
Absolute configuration of 3-acetylbetulinic acid
Автор(ы): Suleimen E. M.*(Van Hecke K.*(Van Meervelt L.*(Deborggraeve W.*(Dehaen W.*
Реферат: The ZnCl2-CO(NH2)(2)-HCl-H2O quaternary system at 25A degrees C was studied by the solubility method. The concentration boundaries of crystallization were established for the phases that correspond to the eutonic compositions of ternary systems, for double carbamide compounds with zinc chloride and hydrochloric acid, and for the compound ZnCl2 center dot 2CO(NH2)(2) center dot HCl.
PUB-NChIP-\"in vivo biotinylation\" approach to study chromatin in proximity to a protein of interest
Автор(ы): Tarlykov P. V.*(Shoaib M.*Kulyyassov A.*(Robin C.*(Winczura K.*(Despas E.*(Kannouche P.*Ramanculov E. M.*(Lipinski M.*(Ogryzko V.*
Объем документа: С. 331-340
МРНТИ: 34.23.17
Ключевые слова: белковый состав хроматина*бактериальный биотин лигаза Бира*хромосомы*масс-спектроскопия*биотин акцептор пептида*гистоны*
Реферат: We have developed an approach termed PUB-NChIP (proximity utilizing biotinylation with native ChIP) to purify and study the protein composition of chromatin in proximity to a nuclear protein of interest. It is based on coexpression of (1) a protein of interest, fused with the bacterial biotin ligase BirA, together with (2) a histone fused to a biotin acceptor peptide (BAP), which is specifically biotinylated by BirA-fusion in the proximity of the protein of interest. Using the RAD18 protein as a model, we demonstrate that the RAD18-proximal chromatin is enriched in some H4 acetylated species. Moreover, the RAD18-proximal chromatin containing a replacement histone H2AZ has a different pattern of H4 acetylation. Finally, biotin pulse-chase experiments show that the H4 acetylation pattern starts to resemble the acetylation pattern of total H4 after the proximity of chromatin to RAD18 has been lost.