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排序方式: 共有369条查询结果,搜索用时 15 毫秒
1.
Alena Orlov 《Materials Science and Engineering: A》1996,220(1-2):117-122
The present work studies the collection of experimental data from which Raj and Pharr (Mater. Sci. Eng., 81 (1986) 217) deduced a universal empirical dependence of the subgrain size on the applied stress. In accord with their result and some theoretical predictions the normalized subgrain size ds/b was ssumed to be proportional to G/σ (G is the shear modulus, b the Burgers vector length, σ the applied stress). The evaluated factor of proportionality K1, having the value within the interval from 0.76 to 180 in the inspected data sets, was discussed from the point of view of various factors which can influence the experimental data. 相似文献
2.
3.
Miriam J. Kavec Marketa Urbanova Pavol Makovicky Alena Opattov Kristyna Tomasova Michal Kroupa Klara Kostovcikova Anna Siskova Nazila Navvabi Michaela Schneiderova Veronika Vymetalkova Ludmila Vodickova Pavel Vodicka 《International journal of molecular sciences》2022,23(10)
Oxidative stress, oxidative DNA damage and resulting mutations play a role in colorectal carcinogenesis. Impaired equilibrium between DNA damage formation, antioxidant status, and DNA repair capacity is responsible for the accumulation of genetic mutations and genomic instability. The lesion-specific DNA glycosylases, e.g., hOGG1 and MUTYH, initiate the repair of oxidative DNA damage. Hereditary syndromes (MUTYH-associated polyposis, NTHL1-associated tumor syndrome) with germline mutations causing a loss-of-function in base excision repair glycosylases, serve as straight forward evidence on the role of oxidative DNA damage and its repair. Altered or inhibited function of above glycosylases result in an accumulation of oxidative DNA damage and contribute to the adenoma-adenocarcinoma transition. Oxidative DNA damage, unless repaired, often gives rise G:C > T:A mutations in tumor suppressor genes and proto-oncogenes with subsequent occurrence of chromosomal copy-neutral loss of heterozygosity. For instance, G>T transversions in position c.34 of a KRAS gene serves as a pre-screening tool for MUTYH-associated polyposis diagnosis. Since sporadic colorectal cancer represents more complex and heterogenous disease, the situation is more complicated. In the present study we focused on the roles of base excision repair glycosylases (hOGG1, MUTYH) in colorectal cancer patients by investigating tumor and adjacent mucosa tissues. Although we found downregulation of both glycosylases and significantly lower expression of hOGG1 in tumor tissues, accompanied with G>T mutations in KRAS gene, oxidative DNA damage and its repair cannot solely explain the onset of sporadic colorectal cancer. In this respect, other factors (especially microenvironment) per se or in combination with oxidative DNA damage warrant further attention. Base excision repair characteristics determined in colorectal cancer tissues and their association with disease prognosis have been discussed as well. 相似文献
4.
Marko J. Tadjer Michael A. Mastro José M. Rojo Alberto Boscá Mojena Fernando Calle Francis J. Kub Charles R. Eddy Jr. 《Journal of Electronic Materials》2014,43(4):1188-1193
Manganese dioxide films were grown on large area flexible carbon aerogel substrates. Characterization by x-ray diffraction confirmed α-MnO2 growth. Three types of films were compared as a function of hexamethylenetetramine (HMTA) concentration during growth. The highest concentration of HM TA produced MnO2 flower-like films, as observed by scanning electron microscopy, whose thickness and surface coverage lead to both a higher specific capacitance and higher series resistance. Specific capacitance was measured to be 64 F/g using a galvanostatic setup, compared to the 47 F/g-specific capacitance of the carbon aerogel substrate. Such supercapacitor devices can be fabricated on large area sheets of carbon aerogel to achieve high total capacitance. 相似文献
5.
Joshua D. Caldwell Kendrick X. Liu Marko J. Tadjer Orest J. Glembocki Robert E. Stahlbush Karl D. Hobart Fritz Kub 《Journal of Electronic Materials》2007,36(4):318-323
Stacking faults within 4H-SiC PiN diodes are known to be detrimental to device operation. Here, we present electroluminescence
(EL) images of 4H-SiC PiN diodes providing evidence that electrically and optically stimulated Shockley stacking fault (SSF)
propagation is a reversible process at temperatures as low as 210°C. Optical beam induced current (OBIC) images taken following
complete optical stressing of a PiN diode and that lead to a small number of completely propagated SSFs provide evidence that
such defects propagate across the n–/p+ interface and continue to grow throughout the p+ layer. These observations bring about
questions regarding the validity of the currently accepted driving force mechanism for SSF propagation. 相似文献
6.
Valeri Smolenski Alena Novoselova Alexander Osipenko 《Journal of Nuclear Materials》2009,385(1):184-71
This work presents the electrochemical study of YbCl3 in molten CsCl in the temperature range 973-1073 K. Transient electrochemical techniques have been used in order to investigate the reduction mechanism, transport parameters and thermodynamics properties of the reaction YbCl2+1/2Cl2=YbCl3. The results obtained show that the reduction reaction is reversible being controlled by the rate of the mass transfer. The diffusion coefficient of [YbCl6]3- complex ions was determined. The apparent standard electrode potential of the soluble-soluble redox system Yb3+/Yb2+ was obtained by cyclic voltammetry. 相似文献
7.
8.
Alena Krupková Jan Čermák 《Journal of Inorganic and Organometallic Polymers and Materials》2012,22(2):470-477
Dendritic polyols of the second and third generation 2G-OH8 (1), 2G-OH16 (2), and 3G-OH16 (3) were prepared by hydroboration/oxidation of allyl-terminated carbosilane dendrimers and used as supports for the immobilization
of cyclopentadienyltrichlorotitanium(IV) complexes via alcoholysis. The reaction of 1–3 with CpTiCl3 gave metallodendrimers 2G-(OTiCpCl2)8 (4a), 2G-(OTiCpCl2)16 (5a), and 3G-(OTiCpCl2)16 (6a), respectively, whereas the reaction of 1 and 3 with CpSiFTiCl3 (CpSiF = C5H4SiMe2CH2CH2C8F17) yielded peripherally fluorinated metallodendrimers 2G-(OTiCpSiFCl2)8 (4b) and 3G-(OTiCpSiFCl2)16 (6b). All metallodendrimers were characterized by multinuclear NMR spectroscopy. The suggested structures were supported by comparison
with model 1-propoxycomplexes 10a,b. To identify side products of the alcoholysis reaction, hydrolytic behavior of the starting trichloro complexes was studied
both in solid state and in solution. The main products of hydrolysis in solution were identified as μ-oxocomplexes 8a,b whereas hydrolysis in solid state yielded mainly hydroxycomplexes 7a,b. 相似文献
9.
Bhoomika Basu Mallik Jenna Stanislaw Tharindu Madhusankha Alawathurage Prof. Dr. Alena Khmelinskaia 《Chembiochem : a European journal of chemical biology》2023,24(15):e202300117
Self-assembling polyhedral protein biomaterials have gained attention as engineering targets owing to their naturally evolved sophisticated functions, ranging from protecting macromolecules from the environment to spatially controlling biochemical reactions. Precise computational design of de novo protein polyhedra is possible through two main types of approaches: methods from first principles, using physical and geometrical rules, and more recent data-driven methods based on artificial intelligence (AI), including deep learning (DL). Here, we retrospect first principle- and AI-based approaches for designing finite polyhedral protein assemblies, as well as advances in the structure prediction of such assemblies. We further highlight the possible applications of these materials and explore how the presented approaches can be combined to overcome current challenges and to advance the design of functional protein-based biomaterials. 相似文献
10.
Vladimir Labunov Alena Prudnikava Serguei Bushuk Serguei Filatov Boris Shulitski Beng Kang Tay Yury Shaman Alexander Basaev 《Nanoscale research letters》2013,8(1):375
Femtosecond lasers (FSL) are playing an increasingly important role in materials research, characterization, and modification. Due to an extremely short pulse width, interactions of FSL irradiation with solid surfaces attract special interest, and a number of unusual phenomena resulted in the formation of new materials are expected. Here, we report on a new nanostructure observed after the interaction of FSL irradiation with arrays of vertically aligned carbon nanotubes (CNTs) intercalated with iron phase catalyst nanoparticles. It was revealed that the FSL laser ablation transforms the topmost layer of CNT array into iron phase nanospheres (40 to 680 nm in diameter) located at the tip of the CNT bundles of conical shape. Besides, the smaller nanospheres (10 to 30 nm in diameter) are found to be beaded at the sides of these bundles. Some of the larger nanospheres are encapsulated into carbon shells, which sometime are found to contain CNTs. The mechanism of creation of such nanostructures is proposed. 相似文献