The clay montmorillonite is known to catalyze the polymerization of RNA from activated ribonucleotides. Here we report that montmorillonite accelerates the spontaneous conversion of fatty acid ...micelles into vesicles. Clay particles often become encapsulated in these vesicles, thus providing a pathway for the prebiotic encapsulation of catalytically active surfaces within membrane vesicles. In addition, RNA adsorbed to clay can be encapsulated within vesicles. Once formed, such vesicles can grow by incorporating fatty acid supplied as micelles and can divide without dilution of their contents by extrusion through small pores. These processes mediate vesicle replication through cycles of growth and division. The formation, growth, and division of the earliest cells may have occurred in response to similar interactions with mineral particles and inputs of material and energy.
The fatigue strengths in notched specimens of carbon fiber reinforced carbon composites (C/C composites) were investigated. The fatigue limit was measured by S-N curves and load increase tests. The ...value of fatigue limit obtained by those methods was almost the same. Slits of several sizes were cut on both sides of a test section, and different sizes of slit length were chosen. Also, specimens with blunt-notches were used to compare the fatigue strength. The weakest fatigue limit was obtained in the case of specimens with blunt-notches. However, the stress concentration factor of those is smaller than that of slit specimens. The relationships between fatigue strengths and specimen shapes were analyzed by stress distribution. The effect of slit configuration on fatigue strength was then discussed regarding the experimental consequences. Consequently, it was discussed that the fatigue strength of the present specimens was determined depending on the damage conditions in the vicinity of the notch and on the crack initiation behavior. It is expected that the tendency of the S-N curve and fatigue limit was related to the shear damage and shear mode of the crack growth.
In back-end-of-the-line (BEOL) patterning process, porous low-k dielectrics are degraded by plasma reactive species during etching and resist stripping -this is so-called plasma induced damage (PID). ...PID increases the k-value of dielectrics and inter-line capacitance, which causes resistive-capacitive (RC) delay. In this paper, the authors introduce two approaches to suppress the PID, using a novel volatile organic film. The first approach is an improved Post Porosity Plasma Protection (P4, or pore stuffing), and the second approach is based on the use of a temporary plug. In the case of pore stuffing, the filling ability and protection effect are evaluated on various blanket low-k dielectric materials. For the plug approach, its effectiveness is demonstrated in terms of electrical characteristics and reliability using a patterned interconnect test vehicle.
Hyperventilation, with the resulting hypocapnia, reduces cerebral blood flow and causes slowing of the EEG activity. However, neuronal oscillating properties including the thalamocortical network ...during hyperventilation have not been elucidated. To assess these features provoked by hyperventilation, the present study examined quadratic phase coupling features by means of bicoherence analysis.
Twenty-two patients were anaesthetized using sevoflurane 1.5% combined with remifentanil or epidural anaesthesia. After a stable normocapnic period, hypocapnia was induced by hyperventilation, and the raw EEG signals were collected. Bispectral analysis (bicoherence) and power spectrum analysis were performed before and after hypocapnia.
Mean (sd) peak bicoherence in the δ–θ area increased from 35.6 (10.9)% during normocapnia to 43.8 (10.9)% during hypocapnia (P<0.05), whereas mean (sd) peak bicoherence in the α area decreased from 42.8 (14.4)% during normocapnia to 37.5 (12.3)% during hypocapnia (P<0.05). Normalized power in the δ−θ frequencies on the power spectrum increased from 60.2 (13.1)% to 72.5 (12.7)% (P<0.05). Bispectral index and spectral edge frequency changed from 45.9 (7.0) to 40.1 (5.6) (P<0.05) and from 15.0 (2.3) to 14.0 (2.5) Hz (P<0.05), respectively. No significant differences in these values were observed between the two types of anaesthesia.
Hypocapnia enlarged bicoherence growth in the δ−θ frequency range, suggesting the contribution of subcortical oscillating mechanisms in regulating EEG during hyperventilation.
Blood–brain barrier (BBB) dysfunction underlies the pathogenesis of many neurological diseases. Platelet-derived growth factor receptor-alpha (PDGFRα) induces hemorrhagic transformation (HT) ...downstream of tissue plasminogen activator in thrombolytic therapy of acute stroke. Thus, PDGFs are attractive therapeutic targets for BBB dysfunction. In the present study, we examined the role of PDGF signaling in the process of tissue remodeling after middle cerebral arterial occlusion (MCAO) in mice. Firstly, we found that imatinib increased lesion size after permanent MCAO in wild-type mice. Moreover, imatinib-induced HT only when administrated in the subacute phase of MCAO, but not in the acute phase. Secondly, we generated genetically mutated mice (C-KO mice) that showed decreased expression of perivascular PDGFRα. Additionally, transient MCAO experiments were performed in these mice. We found that the ischemic lesion size was not affected; however, the recruitment of PDGFRα/type I collagen-expressing perivascular cells was significantly downregulated, and HT and IgG leakage was augmented only in the subacute phase of stroke in C-KO mice. In both experiments, we found that the expression of tight junction proteins and PDGFRβ-expressing pericyte coverage was not significantly affected in imatinib-treated mice and in C-KO mice. The specific implication of PDGFRα signaling was suggestive of protective effects against BBB dysfunction during the subacute phase of stroke. Vascular TGF-β1 expression was downregulated in both imatinib-treated and C-KO mice, along with sustained levels of MMP9. Therefore, PDGFRα effects may be mediated by TGF-β1 which exerts potent protective effects in the BBB.
For the observation of the global three-dimensional distribution of aerosol composition and the evaluation of the shortwave direct radiative effect (SDRE) by aerosols, we developed a retrieval ...algorithm that uses observation data from the Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP) on board the Cloud–Aerosol Lidar Infrared Pathfinder Satellite Observations (CALIPSO) satellite and the Moderate Resolution Imaging Spectroradiometer (MODIS) on board Aqua. The CALIOP–MODIS retrieval optimizes the aerosol composition to both the CALIOP and MODIS observations in the daytime. Aerosols were assumed to be composed of four aerosol components: water-soluble (WS), light-absorbing (LA), dust (DS), and sea salt (SS) particles. The outputs of the CALIOP–MODIS retrieval are the vertical profiles of the extinction coefficient (αa), single-scattering albedo (ω0), asymmetry factor (g) of
total aerosols (WS+LA+DS+SS), and αa of WS, LA, DS, and SS. Daytime observations of CALIOP and MODIS in 2010 were analyzed by the CALIOP–MODIS retrieval. The global means of the aerosol optical depth (τa) at 532 nm were 0.147±0.148 for total aerosols, 0.072±0.085 for WS, 0.027±0.035 for LA, 0.025±0.054 for DS, and 0.023±0.020 for SS. τa of the CALIOP–MODIS retrieval was
between those of the CALIPSO and MODIS standard products and was close to
the MODIS standard product. The global means of ω0 and g were
0.940±0.038 and 0.718±0.037; these values are in the range
of those reported by previous studies. The horizontal distribution of each
aerosol component was reasonable; for example, DS was large in desert
regions, and LA was large in the major regions of biomass burning and
anthropogenic aerosol emissions. The values of τa, ω0, g, and fine and coarse median radii of the CALIOP–MODIS retrieval were compared with those of the AERONET products. τa at 532 and 1064 nm
of the CALIOP–MODIS retrieval agreed well with the AERONET products. The
ω0, g, and fine and coarse median radii of the CALIOP–MODIS
retrieval were not far from those of the AERONET products, but the
variations were large, and the coefficients of determination for linear
regression between them were small. In the retrieval results for 2010, the
clear-sky SDRE values for total aerosols at the top and bottom of the
atmosphere were -4.99±3.42 and -13.10±9.93 W m−2,
respectively, and the impact of total aerosols on the heating rate was from
0.0 to 0.5 K d−1. These results are generally similar to those of
previous studies, but the SDRE at the bottom of the atmosphere is larger
than that reported previously. Consequently, comparison with previous
studies showed that the CALIOP–MODIS retrieval results were reasonable with
respect to aerosol composition, optical properties, and the SDRE.
To improve the beam brightness and the stability of the accelerator for nanobeam and microbeam applications, the Dynamitron accelerator was upgraded. Although the microbeam system at Tohoku ...University can focus the beam to several hundred square micrometers, its beam currents were insufficient for analyses of sub-micrometer resolution because of the lack of the accelerator brightness. For this upgrade, an ion source, with lenses in the terminal, and an acceleration tube were replaced with new ones. A control system for the ion source and lens system was also newly developed. Beam brightness of 2.6 and 0.44
pA
μm
−2
mrad
−2
MeV
−1 is currently obtained for
H
2
+
and
H
1
+
beams at half divergence of 0.07
mrad. The voltage stability of the accelerator was improved by adjusting the voltage stabilizing system, thereby improving the beam current stability. The Dynamitron accelerator has been operated routinely for various experiments without a serious problem.
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