2,846 research outputs found
In-situ cosmogenic <sup>36</sup>Cl denudation rates of carbonates in Guizhou karst area
This study quantifies surface denudation of carbonate rocks by the first application of in-situ cosmogenic <sup>36</sup>Cl in China. Concentrations of natural Cl and in-situ cosmogenic <sup>36</sup>Cl in bare carbonates from Guizhou karst areas were measured with isotope dilution by accelerator mass spectrometer. The Cl concentration varied from 16 to 206 ppm. The <sup>36</sup>Cl concentrations were in range of (0.8–2.4)×106 atom g−1, resulting in total denudation rates of 20–50 mm ka−1 that averaged over a 104–105 a timescale. The <sup>36</sup>Cl-denudation rates showed roughly a negative correlation with the local mean temperature. This preliminary observation may suggest the variations of proportions of chemical weathering and physical erosion in denudation process, depending upon local climatic conditions
Eriodictyol modulates glioma cell autophagy and apoptosis by inhibition of PI3K/Akt/mTOR signaling pathway
Purpose: To investigate the effects of eriodictyol (ERD) on U251 human glioma cell cycle and viability, autophagy and apoptosis by modulation of PI3/Akt/mTOR signaling cascade. Methods: 740 Y-P was used to activate U251 human glioma cells. For exploring ERD effects, the U251 cells were treated with ERD and 740 Y-P together. MTT assay was used to elucidate cell viability and apoptosis. The expression of autophagic proteins (LC3B and Beclin-1), and apoptotic proteins (Bcl-2 and Bax) were quantified using Western blotting. To explore the role of PI3K/Akt/mTOR signaling pathway, their expression was measured in comparison to their respective phosphorylated derivatives by Western blotting. Results: ERD exposure downregulated p-PI3K and p-Akt protein expression. The results also indicate that ERD reduced cell viability and stimulated apoptosis in U251 cells (p < 0.05). Consequently, Bax expression was upregulated and the expression of Bcl-2 was downregulated. ERD enhanced the autophagy of glioma cells U251 by enhancing LC3B and Beclin-1 expression (p < 0.05). These effects were opposite to that revealed by 740 Y-P exposure alone. Conclusion: ERD reduces U251 human glioma cell viability, and triggers cell autophagy and apoptosis, which is significantly correlated to downregulation of PI3K/Akt/mTOR signalling cascade. Thus, the compound can potentially be used for the treatment of glioma
Predicting the activity of chemical compounds based on machine learning approaches
Exploring methods and techniques of machine learning (ML) to address specific
challenges in various fields is essential. In this work, we tackle a problem in
the domain of Cheminformatics; that is, providing a suitable solution to aid in
predicting the activity of a chemical compound to the best extent possible. To
address the problem at hand, this study conducts experiments on 100 different
combinations of existing techniques. These solutions are then selected based on
a set of criteria that includes the G-means, F1-score, and AUC metrics. The
results have been tested on a dataset of about 10,000 chemical compounds from
PubChem that have been classified according to their activit
An inhomogeneous Josephson phase in thin-film and High-Tc superconductors
In many cases inhomogeneities are known to exist near the metal (or
superconductor)-insulator transition, as follows from well-known domain-wall
arguments. If the conducting regions are large enough (i.e. when the T=0
superconducting gap is much larger than the single-electron level spacing), and
if they have superconducting correlations, it becomes energetically favorable
for the system to go into a Josephson-coupled zero-resistance state before
(i.e. at higher resistance than) becoming a "real" metal. We show that this is
plausible by a simple comparison of the relevant coupling constants. For small
grains in the above sense, the electronic grain structure is washed out by
delocalization and thus becomes irrelevant. When the proposed "Josephson state"
is quenched by a magnetic field, an insulating, rather then a metallic, state
should appear. This has been shown to be consistent with the existing data on
oxide materials as well as ultra-thin films. We discuss the Uemura correlations
versus the Homes law, and derive the former for the large-grain Josephson array
(inhomogenous superconductor) model. The small-grain case behaves like a dirty
homogenous metal. It should obey the Homes law provided that the system is in
the dirty supeconductivity limit. A speculation why that is typically the case
for d-wave superconductors is presented.Comment: Conference proceeding for "Fluctuations in Superconductors" held in
Nazareth, Israel in June, 2007; 6 pages with 1 figure, to appear in Physica
Estimating Probable Maximum Precipitation and Probable Maximum Flood by Considering the Combined Effect of Typhoon and Monsoon Weather System under Climate Change
Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive
Recommended from our members
Bottom-up growth of n-type monolayer molecular crystals on polymeric substrate for optoelectronic device applications.
Self-assembly of monolayers of functional molecules on dielectric surfaces is a promising approach for the development of molecular devices proposed in the 1970s. Substrate chemically bonded self-assembled monolayers of semiconducting conjugated molecules exhibit low mobility. And self-assembled monolayer molecular crystals are difficult to scale up and limited to growth on substrates terminated by hydroxyl groups, which makes it difficult to realize sophisticated device functions, particularly for those relying on n-type electron transport, as electrons suffer severe charge trapping on hydroxyl terminated surfaces. Here we report a gravity-assisted, two-dimensional spatial confinement method for bottom-up growth of high-quality n-type single-crystalline monolayers over large, centimeter-sized areas. We demonstrate that by this method, n-type monolayer molecular crystals with high field-effect mobility of 1.24 cm2 V-1 s-1 and band-like transport characteristics can be grown on hydroxyl-free polymer surface. Furthermore, we used these monolayer molecular crystals to realize high-performance crystalline, gate-/light-tunable lateral organic p-n diodes
The closest elastic tensor of arbitrary symmetry to an elasticity tensor of lower symmetry
The closest tensors of higher symmetry classes are derived in explicit form
for a given elasticity tensor of arbitrary symmetry. The mathematical problem
is to minimize the elastic length or distance between the given tensor and the
closest elasticity tensor of the specified symmetry. Solutions are presented
for three distance functions, with particular attention to the Riemannian and
log-Euclidean distances. These yield solutions that are invariant under
inversion, i.e., the same whether elastic stiffness or compliance are
considered. The Frobenius distance function, which corresponds to common
notions of Euclidean length, is not invariant although it is simple to apply
using projection operators. A complete description of the Euclidean projection
method is presented. The three metrics are considered at a level of detail far
greater than heretofore, as we develop the general framework to best fit a
given set of moduli onto higher elastic symmetries. The procedures for finding
the closest elasticity tensor are illustrated by application to a set of 21
moduli with no underlying symmetry.Comment: 48 pages, 1 figur
- …