摘要 :
Earthquake-induced fractures in steel structures are characterised by high-strain low-cycle conditions. In order to investigate the ultra-low cyclic fatigue fracture of steel welded joints under earthquakes, two most commonly used...
展开
Earthquake-induced fractures in steel structures are characterised by high-strain low-cycle conditions. In order to investigate the ultra-low cyclic fatigue fracture of steel welded joints under earthquakes, two most commonly used structural steels (Q235B and Q345B) and the corresponding welds were studied by experiments and numerical analysis in this paper. Specimens were extracted from the base material, the weld metal and the heat affected zone to investigate the behaviour in different parts of the welded joint. Eighteen smooth round bars were tested under large strain amplitudes, the hysteretic properties, damage degradation characteristics and failure process were analyzed. Constitutive model named Chaboche model was calibrated to describe the cyclic hardening behaviour of these materials. Seventy-two notched round bars with three different notch sizes and two loading protocols were tested to study the fracture behaviour of different materials at different stress triaxialities and different strain amplitudes. Two micromechanical fracture models: cyclic void growth model and degraded significant plastic strain model were calibrated based on the test results. The micromechanical models and Chaboche model were incorporated into numerical simulations by software ABAQUS with subroutine VUMAT to predict the materials fracture. The results show that the failure process under cyclic loads is opposite to that of monotone loads. The dissipation capacity of Q345B is superior to that of Q235B. The fracture resistance deteriorate more in the weld zone under the same loading conditions. The validated models can be used to effectively and accurately evaluate the fracture in steel welded connections under ULCF conditions.
收起
摘要 :
High-precision synchronous condition detection and fault diagnosis for bearings are important to reduce the failure rate of rotating machinery products. Therefore, this paper proposes a fast and high-precision diagnosis method bas...
展开
High-precision synchronous condition detection and fault diagnosis for bearings are important to reduce the failure rate of rotating machinery products. Therefore, this paper proposes a fast and high-precision diagnosis method based on multi-sensing fusion and compression features. First, the traditional random weighting method is optimized. The fluctuations of each signal are calculated, and used as the basis for balancing the weighting relationship between the current and historical sampling values, in order to achieve high precision fusion of bearings signals. Second, based on the traditional compression sensing method, the reconstruction part that would further increase the diagnosis error and time is omitted. The partial Hadamard matrix is constructed to retain the feature trend in the compressed signal, and the bearings fault diagnosis based on the compressed features is realized. Finally, the combination of these two methods can reduce the number of signal samples during the collection and transmission process, and realize a direct, fast and accurate diagnosis of the bearings state. Simulation and experimental results verify the superiority and effectiveness of the proposed method.
收起
摘要 :
The rapid economic development and significant expansion of urban agglomerations in China have resulted in issues associated with haze and photochemical smog. Central China, a transitional zone connecting the eastern coast and wes...
展开
The rapid economic development and significant expansion of urban agglomerations in China have resulted in issues associated with haze and photochemical smog. Central China, a transitional zone connecting the eastern coast and western interior, suffers from increasing atmospheric pollution. This study performed a spatio-temporal analysis of fine particulate matter (PM2.5) pollution in Changsha, a provincial capital located in central China. Samples of PM(2.5)were collected at five different functional areas from September 2013 to August 2014. The PM(2.5)concentration at the five sampling sites was the highest in winter and the lowest in summer, with an average annual PM(2.5)concentration of 105.2 +/- 11.0 mu g/m(3). On average, residential sites had the highest concentrations of PM(2.5)while suburban sites had the lowest. We found that inorganic ionic species were dominant (~48%), organic species occupied approximately 25%, whereas EC (~3.7%) contributed insignificantly to the total PM(2.5)mass. Ion balance calculations show that the PM(2.5)samples at all sites were acidic, with increased acidity in spring and summer compared with autumn and winter. Air quality in Changsha is controlled by four major air masses: (1) Wuhan and the surrounding urban clusters, (2) the Changsha-Zhuzhou-Xiangtan urban agglomeration and the surrounding cities, and (3) southern and (4) eastern directions. The north-south transport channel is the most significant air mass trajectory in Changsha and has a significant impact on PM(2.5)pollution.
收起
摘要 :
BACKGROUND: Increasing evidence has established neuroinflammation as the hallmark of neurodegenerative disorders such as Alzheimer's disease (AD). However, despite the underlying immunological mechanisms are far from being underst...
展开
BACKGROUND: Increasing evidence has established neuroinflammation as the hallmark of neurodegenerative disorders such as Alzheimer's disease (AD). However, despite the underlying immunological mechanisms are far from being understood, the involvement of excessive activation of microglia is attracting more and more attention. OBJECTIVE: In the present study, we investigated the protective effect of black raspberry (BRB) anthocyanins on LPS-induced neuroinflammation in BV2 microglia. METHODS: LPS-induced mouse BV2 microglia were treated with black raspberry anthocyanins and the levels of NO, ROS, IL-1 beta and IL-18 produced by the cells were measured to determine the extent of oxidative stress and inflammatory response. RESULTS: The results showed that BRB anthocyanins reduced the production of ROS in LPS-induced BV2 microglia by down-regulating the level of NOX2 and its downstream factors, including thioredoxin-interacting protein (TXNIP) and NOD-like receptor protein 3 (NLRP3) inflammasome. Furthermore, BRB anthocyanins inhibited the secretion of Interleukin-18 (IL-18) and Interleukin-1 beta (IL-1 beta), eventually attenuating the LPS-induced inflammatory response of BV2 microglia. CONCLUSIONS: BRB anthocyanins might play an important neuroprotective role in inflammation-related neurodegenerative disease, potentially, by down-regulating the NOX2/TXNIP/NLRP3 signaling axis in brain microglia.
收起
摘要 :
Ethnopharmacological relevance: Tinospora sinensis (Lour.) Merr. belongs to the family Menispermaceae. It is called LeZhe and is widely used as a kind of folk medicine especially in the Tibetan Plateau of China. T. sinensis has th...
展开
Ethnopharmacological relevance: Tinospora sinensis (Lour.) Merr. belongs to the family Menispermaceae. It is called LeZhe and is widely used as a kind of folk medicine especially in the Tibetan Plateau of China. T. sinensis has the functions of clearing away heat and detoxification, dispelling wind and dredging collaterals, calming and soothing the nerves. T. sinensis is an effective medicine for the prevention and treatment of aging diseases such as Alzheimer's disease (AD) in the Tibetan Plateau of China, whereas its material basis and underlying mechanisms are not clear. The aim of this study was to investigate the material basis and potential mechanisms of T. sinensis in the treatment of AD by using network pharmacology and molecular docking.
收起
摘要 :
Digital watermarking is an effective technique for the digital rights management (DRM) of depth-image-based rendering (DIBR)-based 3D videos, which is still a crucial issue in the 3D TV industry. However, the existing watermarking...
展开
Digital watermarking is an effective technique for the digital rights management (DRM) of depth-image-based rendering (DIBR)-based 3D videos, which is still a crucial issue in the 3D TV industry. However, the existing watermarking schemes for DIBR-based 3D videos either cause irreversible distortions in the synthesized 3D videos or are not robust against some of the typical video attacks. In this paper, a novel robust and synthesized unseen watermarking scheme is proposed for the DRM of DIBR-based 3D videos. This scheme embeds watermarks into the pseudo-3D-discrete cosine transform (3D-DCT) domain of the depth maps based on quantization index modulation (QIM) and determines the embedding strength based on a novel self-adaptive mechanism. Our analysis and experiments demonstrate that our proposed scheme not only avoids distortion in the synthesized 3D videos but also is sufficiently robust against various attacks, with average normalized correlations (NCs) between original and extracted watermarks higher than 0.9819 and average bit error rates (BERs) lower than 0.0196. Therefore, the proposed scheme offers a better solution for the DRM of DIBR-based 3D videos than the current state-of-the-art watermarking schemes.
收起
摘要 :
An integrated and quantitative evaluation method based on soil pollution, land use, risk receptor vulnerability, and risk source was developed to assess soil risk in a de-industrialized area. A case study was conducted to understa...
展开
An integrated and quantitative evaluation method based on soil pollution, land use, risk receptor vulnerability, and risk source was developed to assess soil risk in a de-industrialized area. A case study was conducted to understand the spatial and temporal characteristics of soil risk, and the resulting comprehensive soil risk values ranged from 128.24 to 2,3670.50 in 2008 and from 104.08 to 3,8421.70 in 2015. However, this overall increase was inconsistent with the soil pollution trend. The extended Pearson correlation coefficient (ePCC) was calculated for 39,655 extracted data points to comprehensively characterize the risks associated with soil pollution. The ePCC was greater than 1 in most developed and undeveloped blocks, indicating that comprehensive soil risks in these regions were relatively stable and less affected by changes in soil pollution status upon de-industrialization. The ePCC was lower than 0.99 in approximately 35.23% of the study area blocks, where changes in human-land relationships were strong. This study highlighted the complexity of risk characteristics and trends after de-industrialization. Therefore, more precise and regionalized soil risk management methods based on comprehensive risk assessment procedures are required in de-industrialized areas. (C) 2020 Elsevier Ltd. All rights reserved.
收起
摘要 :
The RAS and mTOR inhibitor S-trans-trans-famesylthiosalicylic acid (FTS) is a promising anticancer agent with moderate potency, currently undergoing clinical trials as a chemotherapeutic agent. FTS has displayed its potential agai...
展开
The RAS and mTOR inhibitor S-trans-trans-famesylthiosalicylic acid (FTS) is a promising anticancer agent with moderate potency, currently undergoing clinical trials as a chemotherapeutic agent. FTS has displayed its potential against a variety of cancers including endocrine resistant breast cancer. However, the poor pharmacokinetics profile attributed to its high hydrophobicity is a major hindrance for its continued advancement in clinic. One of the ways to improve its therapeutic potential would be to enhance its bioavailability to cancer tissue by developing a method for targeted delivery. In the current study, FTS was conjugated with the cancer-targeting heptamethine cyanine dye 5 to form the FTS dye conjugate 11. The efficiency tumor targeting properties of conjugate 11 against cancer cell growth and mTOR inhibition was evaluated in vitro in comparison with parent FTS. Cancer targeting of 11 in a live mouse model of MCF7 xenografts was demonstrated with noninvasive, near infrared fluorescence (NIRF). imaging. The results from our studies clearly suggest that the bioavailability of FTS is indeed" improved as indicated by log P values and cancer cell uptake. The FTS dye conjugate 11 displayed higher potency (IC50 = 16.8 +/- 0.5 mu M) than parent FTS (IC50 = similar to 51.3 +/- 1.8 mu M) and inhibited mTOR activity in the cancer cells at a lower concentration (12.5 mu M). The conjugate 11 was shown to be specifically accumulated in tumors as observed by in vivo NIRF imaging, organ distribution, and ex vivo tumor histology along with cellular level confocal microscopy. In conclusion, the conjugation of FTS with cancer-targeting heptamethine cyanine dye improved its pharmacological profile.
收起
摘要 :
Recently, Traditional Chinese Medicines (TCMs), having a rich history in China for their use in maintaining health and treating disease, have gained popularity worldwide. However, their modernization and globalization are impeded ...
展开
Recently, Traditional Chinese Medicines (TCMs), having a rich history in China for their use in maintaining health and treating disease, have gained popularity worldwide. However, their modernization and globalization are impeded due to their "multi-component, multi-pathway, and multi-target" properties. Chemometrics, a comprehensive product of statistics, computers, and information, is an interfacial discipline that extracts practical information from large chemical and biochemical datasets, beneficial to overcome TCMs restrictions. This review summarized key research findings on the basis and application of TCMs according to their components, authenticity, processing conditions, geographical origin, pharmacological activity, and metabolomics based on recent studies. Here, we discussed the benefits and shortcomings of cluster analysis, principal component analysis, soft independent modeling of class analogy, artificial neural networks, support vector machine, partial least squares-discriminant analysis, data fusion and calibration, and the appropriate application of these methods in different fields of TCMs. This review aimed to provide a basic understanding of the role and perspectives of chemometrics in the spectroscopic and chromatographic analysis of TCMs.
收起
摘要 :
China has extensively implemented the Joint Prevention and Control of Atmospheric Pollution (JPCAP) strategy to address regional air pollution challenges; however, the lack of accurate scope and regional priority control sequence ...
展开
China has extensively implemented the Joint Prevention and Control of Atmospheric Pollution (JPCAP) strategy to address regional air pollution challenges; however, the lack of accurate scope and regional priority control sequence has resulted in reduced pollution control efficiency and high air quality improvement costs. We proposed the following new solutions to these problems: (i) constructing inter-regional network correlation models based on three key network topology parameters and (ii) subdividing large regions into sub-regions using the Girvan Newman (GN) algorithm. To test these methods, we applied them to a case study of China's provinciallevel JPCAP areas using hourly air resource endowment (ARE) data obtained from 2013 to 2017. We found that the modularity (Q) values of ARE network partitioning in different seasons were approximately 0.5, indicating the well-structured association of the network constructed in this study. Seven areas were identified based on annual values, while eight, five, four, and six areas were classified for spring, summer, autumn, and winter, respectively. The strength of the interconnectedness of the provinces in the region, as measured by the clustering coefficient (C) value, is ordered as follows: Autumn > winter > spring > summer. For a specific JPCAP region, the priority control level can be dynamically adjusted based on the Pearson correlation coefficient (r-value) between the target city or province and the surrounding region. The regional division results, priority control sequences, and key control seasons identified in this study can provide technical and methodological reference for delineating and optimizing China's JPCAP policy.
收起
原文获取