2,492 research outputs found
Experimental and Numerical Analysis of Rock Burst Tendency and Crack Development Characteristics of Tianhu Granite
Rock burst is a serious nonlinear dynamic geological hazard in underground engineering construction. In this paper, a true triaxial unloading rock burst experiment and numerical simulation are carried out on Tianhu granite to investigate the rock burst tendency and crack development characteristics of surrounding rock after excavation. The experiment and numerical simulation process monitored the rock burst stress path to determine the rock burst stress. According to the evolution law of the frequency and amplitude of rock burst acoustic emission monitoring, the shape characteristics of rock burst fragments are analyzed. The rock burst numerical simulation analysis is carried out by the PFC software, and the temporal and spatial evolution law of cracks is obtained. The research results show that the laboratory experiment and numerical simulation of Tianhu granite have rock burst strengths of 163.4 MPa and 161 MPa, respectively, and the average rock burst stress ratio is 8.38, that is, the Tianhu granite has a low rock burst tendency. During the rock burst, the development of tensile cracks will produce flaky debris, and the development of shear cracks will produce lumpy debris. Rock burst will happen when the crack growth rate to be exceeded the unloading crack growth rate; therefore, it can be used as a precursor signal for the occurrence of rock burst
Recollements induced by left Frobenius pairs
Let be a right exact functor from an abelian category into
another abelian category . Then there exists an abelian category,
named comma category and denoted by .In this paper,
we construct left Frobenius pairs (resp. strong left Frobenius pairs) over
using left Frobenius pairs (resp. strong left
Frobenius pairs) over and As a consequence, we
obtain a recollement of (right) triangulated categories, generalizing the
result of Xiong-Zhang-Zhang (J. Algebra 503 (2018) 21-55) about the recollement
of additive (resp. triangulated) categories constructed from a triangular
matrix algebra. This result is applied to the classes of flat modules and
Gorenstein flat modules, the classes of Gorenstein projective modules and
Gorenstein projective complexes, the class of Ding projective modules and the
class of Gorenstein flat-cotorsion modules.Comment: 24 pages, all comments are welcom
Higher Auslander's defect and classifying substructures of n-exangulated categories
Herschend-Liu-Nakaoka introduced the notion of -exangulated categories. It
is not only a higher dimensional analogue of extriangulated categories defined
by Nakaoka-Palu, but also gives a simultaneous generalization of -exact
categories and -angulated categories. In this article, we give an
-exangulated version of Auslander's defect and Auslander-Reiten duality
formula. Moreover, we also give a classification of substructures (=closed
subbifunctors) of a given skeletally small -exangulated category by using
the category of defects.Comment: 24 pages. arXiv admin note: text overlap with arXiv:1709.06689 by
other author
Arborinol methyl ether from Areca catechu L.
The title compound isolated from Areca catechu L. (common name: arborinol methyl ether; a member of the arborane family) was established as 3α-methoxyarbor-9(11)-ene, C31H52O. Rings A/B/C/D assume a chair conformation, while ring E has an envelope conformation. The absolute configuration was determined to be (3R,5R,8S,10S,13R,14S,17S,18S, 21S) by analysis of Bijvoet pairs based on resonant scattering of light atoms, yielding a Hooft parameter y of −0.03 (3)
Aggregation of TDP-43 fragments triggers cellular aberrant function: implication in neurodegeneration
Changes of AM Fungal Abundance along Environmental Gradients in the Arid and Semi-Arid Grasslands of Northern China
Arbuscular mycorrhizal (AM) fungi are ubiquitous symbionts of higher plants in
terrestrial ecosystems, while the occurrence of the AM symbiosis is influenced
by a complex set of abiotic and biotic factors. To reveal the regional
distribution pattern of AM fungi as driven by multiple environmental factors,
and to understand the ecological importance of AM fungi in natural ecosystems,
we conducted a field investigation on AM fungal abundance along environmental
gradients in the arid and semi-arid grasslands of northern China. In addition
to plant parameters recorded in situ, soil samples were collected, and soil
chemo-physical and biological parameters were measured in the lab. Statistical
analyses were performed to reveal the relative contribution of climatic,
edaphic and vegetation factors to AM fungal abundance, especially for
extraradical hyphal length density (HLD) in the soil. The results indicated
that HLD were positively correlated with mean annual temperature (MAT), soil
clay content and soil pH, but negatively correlated with both soil organic
carbon (SOC) and soil available N. The multiple regressions and structural
equation model showed that MAT was the key positive contributor and soil
fertility was the key negative contributor to HLD. Furthermore, both the
intraradical AM colonization (IMC) and relative abundance of AM fungi, which
was quantified by real-time PCR assay, tended to decrease along the increasing
SOC content. With regard to the obvious negative correlation between MAT and
SOC in the research area, the positive correlation between MAT and HLD implied
that AM fungi could potentially mitigate soil carbon losses especially in
infertile soils under global warming. However, direct evidence from long-term
experiments is still expected to support the AM fungal contribution to soil
carbon pools
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