Identification Methods of the Deformation Memory Effect in the Stress Region above Crack Initiation Threshold

AbstractDeformation memory effect (DME) is one of the rock memory effects. One important application of the DME is to determine the in situ stress state. Compared to the traditional in situ stress measurements, the methods based on the DME are commercial and permit large number of measurements. Application of DME needs enough reliable identification methods. However, the existing methods sometimes are indistinct and the amount is insufficient. combined with three traditional methods including tangential modulus method, deformation rate analysis (DRA), acoustic emission method, two new potential methods were explored in the stress region above crack initiation threshold. One is based on the fractal dimension, called FD method. Another one is to take advantage of the lateral strain in the DRA method and the FD method, instead of using the axial strain. Based on the contact bond model in PFC2D, numerical model for granite sample was developed and cyclic uniaxial compressions were performed on it. Both the existing methods and new methods were used to detect the DME. The results demonstrate that the FD method is effective and reliable, result by DRA method with lateral strain is better than that with the axial strain, the tangential modulus method is not so distinct as other methods

Asymptotic results in-over and under-representation of words in DNA

Master'sMASTER OF SCIENC

The Relationship between M&A Short Performance and Payment Method ----China Market in 2015

This thesis aim to examine the relationship between short term performance and payment method in M&A event. However, we just include pure equity and pure cash offers. It has other factors will affect the mixed offers’ performance except equity and cash. Firstly, we introduce some basic information about merger and acquisition. We define what are merger and acquisition and how to measure their performance. And then we introduce the methods of payment including equity and cash. We use event study method to find that there are extra returns through merger and acquisition. Besides, we use regress analysis find that the bidder’s size, TobinQ and payment method have positive impact on acquiring’s short term performance

Estimation of the Conifer-Broadleaf Ratio in Mixed Forests Based on Time-Series Data

Most natural forests are mixed forests, a mixed broadleaf-conifer forest is essentially a heterogeneously mixed pixel in remote sensing images. Satellite missions rely on modeling to acquire regional or global vegetation parameter products. However, these retrieval models often assume homogeneous conditions at the pixel level, resulting in a decrease in the inversion accuracy, which is an issue for heterogeneous forests. Therefore, information on the canopy composition of a mixed forest is the basis for accurately retrieving vegetation parameters using remote sensing. Medium and high spatial resolution multispectral time-series data are important sources for canopy conifer-broadleaf ratio estimation because these data have a high frequency and wide coverage. This paper highlights a successful method for estimating the conifer-broadleaf ratio in a mixed forest with diverse tree species and complex canopy structures. Experiments were conducted in the Purple Mountain, Nanjing, Jiangsu Province of China, where we collected leaf area index (LAI) time-series and forest sample plot inventory data. Based on the Invertible Forest Reflectance Model (INFORM), we simulated the normalized difference vegetation index (NDVI) time-series of different conifer-broadleaf ratios. A time-series similarity analysis was performed to determine the typical separable conifer-broadleaf ratios. Fifteen Gaofen-1 (GF-1) satellite images of 2015 were acquired. The conifer-broadleaf ratio estimation was based on the GF-1 NDVI time-series and semi-supervised k-means cluster method, which yielded a high overall accuracy of 83.75%. This study demonstrates the feasibility of accurately estimating separable conifer-broadleaf ratios using field measurement data and GF-1 time series in mixed broadleaf-conifer forests

Effects of Polypyrrole/Graphene Oxide Composites with Different Reaction Times on Electrochemical Performance

Graphene oxide (GO) was prepared using the modified Hummers method and used as a template for polypyrrole. Polypyrrole was polymerized in situ on the surface of GO to finally obtain the polypyrrole/graphene oxide composite material. The effects of different reaction times on the electrochemical performance of polypyrrole/graphene oxide in the second step were studied. It was obtained that the composite material had optimal properties when the reaction time was 24 h

Adsorption tuning of polarity and magnetism in AgCr2S4 monolayer

As a recent successfully exfoliated non van der Waals layered material, AgCrS2 has received a lot of attentions. Motivated by its structure related magnetic and ferroelectric behavior, a theoretical study on its exfoliated monolayer AgCr2S4 has been carried out in the present work. Based on density functional theory, the ground state and magnetic order of monolayer AgCr2S4 have been determined. The centrosymmetry emerges upon two-dimensional confinement and thus eliminates the bulk polarity. Moreover, two-dimensional ferromagnetism appears in the CrS2 layer of AgCr2S4 and can persist up to room temperature. The surface adsorption has also been taken into consideration, which shows a nonmonotonic effect on the ionic conductivity through ion displacement of the interlayer Ag, but has little impact on the layered magnetic structure.Comment: 9 oages, 5 figures, 2 table

Synthesis and Characterization of 4,4′-Dibromoazobenzene

Abstract: Azobenzene molecules show excellent application potential in many fields due to their photoisomerization properties. Azobenzene molecules will gradually change from trans-structure to cis-structure under the irradiation of UV. In this paper, we have synthesized 4,4'-dibromoazobenzene molecules and characterized their photoisomerization properties. We found that with the extension of UV time, the trans absorption peak at 343 nm decreased significantly, while the cis absorption peak at 435 nm showed an upward trend. Furthermore, photoisomerization of azobenzene is not a first-order reaction

Melatonin enhances the anti-tumor effect of fisetin by inhibiting COX-2/iNOS and NF-κB/p300 signaling pathways.

Melatonin is a hormone identified in plants and pineal glands of mammals and possesses diverse physiological functions. Fisetin is a bio-flavonoid widely found in plants and exerts antitumor activity in several types of human cancers. However, the combinational effect of melatonin and fisetin on antitumor activity, especially in melanoma treatment, remains unclear. Here, we tested the hypothesis that melatonin could enhance the antitumor activity of fisetin in melanoma cells and identified the underlying molecular mechanisms. The combinational treatment of melanoma cells with fisetin and melatonin significantly enhanced the inhibitions of cell viability, cell migration and clone formation, and the induction of apoptosis when compared with the treatment of fisetin alone. Moreover, such enhancement of antitumor effect by melatonin was found to be mediated through the modulation of the multiply signaling pathways in melanoma cells. The combinational treatment of fisetin with melatonin increased the cleavage of PARP proteins, triggered more release of cytochrome-c from the mitochondrial inter-membrane, enhanced the inhibition of COX-2 and iNOS expression, repressed the nuclear localization of p300 and NF-κB proteins, and abrogated the binding of NF-κB on COX-2 promoter. Thus, these results demonstrated that melatonin potentiated the anti-tumor effect of fisetin in melanoma cells by activating cytochrome-c-dependent apoptotic pathway and inhibiting COX-2/iNOS and NF-κB/p300 signaling pathways, and our study suggests the potential of such a combinational treatment of natural products in melanoma therapy