Changes in the contents of 36 mRNAs species related to lipid turnover, inflammation, metabolism and the action of sex hormones in samples of aortal intima along the “intact tissue — lesions of type I ...— lesions of type II — lesions of type Va” sequence were analyzed using quantitative PCR. The expression of several mRNAs coding for components of the vesicular transfer and lipid turnover machinery was found to be resistant to atherogenesis or even decline in the course of atherogenesis. Decrease in expression was also recorded for steroid sulfatase, androgen receptor, and low density lipoprotein receptor mRNAs. However, the contents of the majority of other mRNA species increased gradually during disease progression. The earliest changes found as early as in lesions of type I were characteristic for estrogen sulfotransferase, apolipoprotein E, scavenger receptor SR-BI, collagen COL1A2, as well as chemokine CCL18 mRNAs. The contents of several mRNAs in intact tissue and atherosclerotic injuries had gender differences. Additionally, responses of two mRNAs, for aromatase and sterol regulatory element binding protein 2, to atherosclerotic lesion were also sex-differentiated. The contents of the majority of analyzed mRNAs in peripheral blood monocyte-derived macrophages were higher than in intact aorta. The correlations found in atherosclerotic lesions between mRNA species that predominant in macrophages and those expressed at comparable levels in macrophages and intact aorta or mainly in aorta suggest that the observed rise in the content of the majority of mRNAs during atherogenesis is determined by increase in expression in resident cells. The data suggest that the revealed absence of homeostatic regulation of expression of a number of genes associated with vesicular transfer and lipid turnover can serve as one of the reasons for lysosomal function insufficiency that leads to foam cell formation in atheroma. The observed sex differences in expression of a number of mRNAs suggest that estrogens in women perform their atheroprotective effects starting with predisposition to the disease and finishing with advanced stages of the pathologic process.
Molecular Doping of Graphene Wehling, T. O; Novoselov, K. S; Morozov, S. V ...
Nano letters,
01/2008, Volume:
8, Issue:
1
Journal Article
Peer reviewed
Open access
Graphene is considered as one of the most promising materials for post silicon electronics, as it combines high electron mobility with atomic thickness Novoselov et al. Science 2004, 306, 666−669. ...Novoselov et al. Proc. Natl. Acad. Sci. U.S.A. 2005, 102, 10451−10453. The possibility of chemical doping and related excellent chemical sensor properties of graphene have been demonstrated experimentally Schedin et al. Nat. Mater. 2007, 6, 652−655, but a microscopic understanding of these effects has been lacking, so far. In this letter, we present the first joint experimental and theoretical investigation of adsorbate-induced doping of graphene. A general relation between the doping strength and whether adsorbates are open- or closed-shell systems is demonstrated with the NO2 system: The single, open shell NO2 molecule is found to be a strong acceptor, whereas its closed shell dimer N2O4 causes only weak doping. This effect is pronounced by graphene's peculiar density of states (DOS), which provides an ideal situation for model studies of doping effects in semiconductors. We show that this DOS is ideal for “chemical sensor” applications and explain the recently observed Schedin et al. Nat. Mater. 2007, 6, 652−655 NO2 single molecule detection.
At very small twist angles of ∼0.1°, bilayer graphene exhibits a strain-accompanied lattice reconstruction that results in submicron-size triangular domains with the standard, Bernal stacking. If the ...interlayer bias is applied to open an energy gap inside the domain regions making them insulating, such marginally twisted bilayer graphene is expected to remain conductive due to a triangular network of chiral one-dimensional states hosted by domain boundaries. Here we study electron transport through this helical network and report giant Aharonov-Bohm oscillations that reach in amplitude up to 50% of resistivity and persist to temperatures above 100 K. At liquid helium temperatures, the network exhibits another kind of oscillations that appear as a function of carrier density and are accompanied by a sign-changing Hall effect. The latter are attributed to consecutive population of the narrow minibands formed by the network of one-dimensional states inside the gap.
A new physical mechanism or mode of plastic deformation in nanocrystalline metals and ceramics is suggested and theoretically described. The mode represents the cooperative grain boundary (GB) ...sliding and stress-driven GB migration process. It is theoretically revealed that the new deformation mode is more energetically favorable than "pure" GB sliding and enhances the ductility of nanocrystalline solids in wide ranges of their structural parameters.
A theoretical model is suggested which describes the effect of special rotational deformation on crack growth in deformed nanocrystalline ceramics and metals. Within the model, the special rotational ...deformation (driven by the external stress concentrated near the tip of a mode I crack) occurs in a nanograin through formation of immobile disclinations whose strengths gradually increase during the formation process conducted by grain boundary sliding and diffusion. The special rotational deformation releases, in part, local stresses near the crack tip, thus serving as a toughening mechanism in nanocrystalline materials. The effects of the special rotational deformation on the growth of pre-existent, comparatively large cracks in nanocrystalline metals and ceramics are estimated.
In this paper, the character of coupled longitudinal-flexural vibrations of a rod is investigated in the case of an internal combinational resonance between two flexural and lower longitudinal ...vibration modes. An approximate analytical solution is obtained by a multiple time-scales method applied directly to a system of nonlinear partial differential equations. It is shown that the initial perturbation in the longitudinal direction can effectively excite bending vibration modes, which, on the whole, leads to a longitudinal-transverse beating regime with noticeable amplitudes. It is noted that the period and amplitude of these beats substantially depend on the frequency detuning parameter between the sum of the bending vibration frequencies and the longitudinal vibration frequency. This effect can be used as a new principle of operation of opto-thermally excited N/MEMS resonant sensors.
The main characteristic of the converter element in resonant microwave sensors that determines the sensitivity of the conversion is the quality factor of the resonance line. In structures with ...periodic inhomogeneity of the classical topology, the quality factor of the circuit at high values of the signal-to-noise ratio may turn out to be low, which entails the emergence of restrictions on the maximum achievable conversion parameters. One of the ways to increase both the Q factor and the modification of other properties of the microwave structure that affect the overall efficiency of the converter element is the use of quasiperiodic elements. The coaxial cable, where the holes in the dielectric act as inhomogeneity, is presented, forming structure with phase shift. Using the method of flow graphs, we obtained the analytical dependence of the reflection coefficient for this structure. The analysis of the frequency response of the microwave reflection coefficient was carried out for different values of the phase shift and the location of the phase shift section along the length of the cable. A numerical and physical experiments were carried out to determine the frequency dependence of the microwave reflection coefficient with a π-phase shift for various values of the automobile fuel permittivity introduced into the cells.
Based on analytical data on the geochemistry of tectonic pseudotachylytes and their host rocks, the specific trends of redistribution of major, trace, and rare earth elements in the course of ...seismogenic frictional melting of the arkosic metaterrigenous rocks from three zones of regional metamorphism with different temperatures (greenschist, amphibolite, and granulite) in the Northern Ladoga region are discussed. Oppositely directed trends of changes in the contents of the oxides of major elements in the protolith–blastocataclasite–pseudotachylyte triad were revealed, and a unidirectional increase in the basicity of the frictional melt as compared with the protolith was established at the same time. Geochemical evidence for partial selective melting of the protoliths is discussed. The specific features of the fractionation of trace and rare-earth elements during the transition of the protolith into the melt, as well as during its subsequent partial recrystallization, are shown. The emergence of a peak of elevated europium contents relative to the protolith in the melt matrix of all three sampling points is noted. Based on changes in the concentrations of these elements in the zones of pseudotachylyte substrate generation and in the areas of its moving and injection, the estimates of their differential mobility during frictional melting in a dynamic slip zone are given.
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