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Reduction kinetics of SrFeO/CaO∙MnO nanocomposite as effective oxygen carrier for chemical looping partial oxidation of methane

《化学科学与工程前沿(英文)》 2022年 第16卷 第12期   页码 1726-1734 doi: 10.1007/s11705-022-2188-5

摘要: Chemical looping reforming of methane is a novel and effective approach to convert methane to syngas, in which oxygen transfer is achieved by a redox material. Although lots of efforts have been made to develop high-performance redox materials, a few studies have focused on the redox kinetics. In this work, the kinetics of SrFeO3−δ–CaO∙MnO nanocomposite reduction by methane was investigated both on a thermo-gravimetric analyzer and in a packed-bed microreactor. During the methane reduction, combustion occurs before the partial oxidation and there exists a transition between them. The weight loss due to combustion increases, but the transition region becomes less inconspicuous as the reduction temperature increased. The weight loss associated with the partial oxidation is much larger than that with combustion. The rate of weight loss related to the partial oxidation is well fitted by the Avrami–Erofeyev equation with n = 3 (A3 model) with an activation energy of 59.8 kJ∙mol‒1. The rate law for the partial oxidation includes a solid conversion term whose expression is given by the A3 model and a methane pressure-dependent term represented by a power law. The partial oxidation is half order with respect to methane pressure. The proposed rate law could well predict the reduction kinetics; thus, it may be used to design and/or analyze a chemical looping reforming reactor.

关键词: chemical looping reforming     SrFeO3−δ/CaO·MnO nanocomposite     reduction kinetics     Avrami–Erofeyev model     pressure-dependent term    

Urotensin II receptor antagonist reduces hepatic resistance and portal pressure through enhanced eNOS-dependent

Ruoxi Zhang, Jing Chen, Diangang Liu, Yu Wang

《医学前沿(英文)》 2019年 第13卷 第3期   页码 398-408 doi: 10.1007/s11684-019-0689-5

摘要: Increased serum urotensin II (UII) levels in human cirrhotic populations have been recently shown, but the long-term effects of UII receptor antagonist on the cirrhosis have not been investigated. To investigate the therapeutic effects of urotensin II receptor (UT) antagonist palosuran on rats with carbon tetrachloride (CCl )-induced cirrhosis, the hepatic and systemic hemodynamics, liver fibrosis, the metalloproteinase-13 (MMP-13)/ tissue inhibitor of metalloproteinase-1 (TIMP-1) ratio, hepatic Rho-kinase activity, and the endothelial nitric oxide synthase (eNOS) activity are measured in CCl -cirrhotic rats treated with palosuran or vehicle for 4 weeks. Primary hepatic stellate cells (HSCs) are used to investigate the changes in UII/UT expression and the effect of palosuran. Compared with the vehicle-treated cirrhotic rats, treatment with palosuran can reduce the portal pressure (PP), decrease the risk of liver fibrosis and the level of α smooth muscle actin, collagen-I (COL-I), and transforming growth factor β expression. However, treatment with palosuran can increase MMP-13/TIMP-1, p-vasodilator-stimulated phosphoprotein (p-VASP), and p-eNOS expression. Moreover, UII/UT mRNA expression increases during HSC activation. MMP-13/TIMP-1, COL-I, and p-VASP are inhibited after palosuran treatment. Our data indicate that long-term administration of palosuran can decrease PP in cirrhosis, which results from decreased hepatic fibrosis and enhanced eNOS-dependent HSC vasodilatation.

关键词: portal hypertension     cirrhosis     urotensin II     palosuran     hepatic stellate cell    

Data-driven approach to solve vertical drain under time-dependent loading

《结构与土木工程前沿(英文)》 2021年 第15卷 第3期   页码 696-711 doi: 10.1007/s11709-021-0727-7

摘要: Currently, the vertical drain consolidation problem is solved by numerous analytical solutions, such as time-dependent solutions and linear or parabolic radial drainage in the smear zone, and no artificial intelligence (AI) approach has been applied. Thus, in this study, a new hybrid model based on deep neural networks (DNNs), particle swarm optimization (PSO), and genetic algorithms (GAs) is proposed to solve this problem. The DNN can effectively simulate any sophisticated equation, and the PSO and GA can optimize the selected DNN and improve the performance of the prediction model. In the present study, analytical solutions to vertical drains in the literature are incorporated into the DNN–PSO and DNN–GA prediction models with three different radial drainage patterns in the smear zone under time-dependent loading. The verification performed with analytical solutions and measurements from three full-scale embankment tests revealed promising applications of the proposed approach.

关键词: vertical drain     artificial neural network     time-dependent loading     deep learning network     genetic algorithm     particle swarm optimization    

Chloride binding and time-dependent surface chloride content models for fly ash concrete

S. MUTHULINGAM,B. N. RAO

《结构与土木工程前沿(英文)》 2016年 第10卷 第1期   页码 112-120 doi: 10.1007/s11709-015-0322-x

摘要: Corrosion of embedded rebars is a classical deterioration mechanism of reinforced concrete structures exposed to chloride environments. Such environments can be attributed to the presence of seawater, deicing or sea-salts, which have high concentrations of chloride ion. Chloride ingress into concrete, essential for inducing rebar corrosion, is a complex interaction between many physical and chemical processes. The current study proposes two chloride ingress parameter models for fly ash concrete, namely: 1) surface chloride content under tidal exposure condition; and 2) chloride binding. First, inconsistencies in surface chloride content and chloride binding models reported in literature, due to them not being in line with past research studies, are pointed out. Secondly, to avoid such inconsistencies, surface chloride content and chloride binding models for fly ash concrete are proposed based upon the experimental work done by other researchers. It is observed that, proposed models are simple, consistent and in line with past research studies reported in literature.

关键词: binding isotherms     chloride ingress     concrete     fly ash     surface chloride content    

GDF15 negatively regulates chemosensitivity via TGFBR2-AKT pathway-dependent metabolism in esophageal

《医学前沿(英文)》 2023年 第17卷 第1期   页码 119-131 doi: 10.1007/s11684-022-0949-7

摘要: Treating patients with esophageal squamous cell carcinoma (ESCC) is challenging due to the high chemoresistance. Growth differentiation factor 15 (GDF15) is crucial in the development of various types of tumors and negatively related to the prognosis of ESCC patients according to our previous research. In this study, the link between GDF15 and chemotherapy resistance in ESCC was further explored. The relationship between GDF15 and the chemotherapy response was investigated through in vitro and in vivo studies. ESCC patients with high levels of GDF15 expression showed an inferior chemotherapeutic response. GDF15 improved the tolerance of ESCC cell lines to low-dose cisplatin by regulating AKT phosphorylation via TGFBR2. Through an in vivo study, we further validated that the anti-GDF15 antibody improved the tumor inhibition effect of cisplatin. Metabolomics showed that GDF15 could alter cellular metabolism and enhance the expression of UGT1A. AKT and TGFBR2 inhibition resulted in the reversal of the GDF15-induced expression of UGT1A, indicating that TGFBR2-AKT pathway-dependent metabolic pathways were involved in the resistance of ESCC cells to cisplatin. The present investigation suggests that a high level of GDF15 expression leads to ESCC chemoresistance and that GDF15 can be targeted during chemotherapy, resulting in beneficial therapeutic outcomes.

关键词: GDF15     esophageal squamous cell carcinoma     chemoresistance     cellular metabolism     TGFBR2     AKT    

Analysis of dispatching rules in a stochastic dynamic job shop manufacturing system with sequence-dependent

Pankaj SHARMA,Ajai JAIN

《机械工程前沿(英文)》 2014年 第9卷 第4期   页码 380-389 doi: 10.1007/s11465-014-0315-9

摘要:

Stochastic dynamic job shop scheduling problem with consideration of sequence-dependent setup times are among the most difficult classes of scheduling problems. This paper assesses the performance of nine dispatching rules in such shop from makespan, mean flow time, maximum flow time, mean tardiness, maximum tardiness, number of tardy jobs, total setups and mean setup time performance measures viewpoint. A discrete event simulation model of a stochastic dynamic job shop manufacturing system is developed for investigation purpose. Nine dispatching rules identified from literature are incorporated in the simulation model. The simulation experiments are conducted under due date tightness factor of 3, shop utilization percentage of 90 % and setup times less than processing times. Results indicate that shortest setup time (SIMSET) rule provides the best performance for mean flow time and number of tardy jobs measures. The job with similar setup and modified earliest due date (JMEDD) rule provides the best performance for makespan, maximum flow time, mean tardiness, maximum tardiness, total setups and mean setup time measures.

关键词: scheduling     stochastic dynamic job shop     sequence-dependent setup times     dispatching rule     simulation    

Stabilization-based soil remediation should consider long-term challenges

Zhengtao Shen, Zhen Li, Daniel S. Alessi

《环境科学与工程前沿(英文)》 2018年 第12卷 第2期 doi: 10.1007/s11783-018-1028-9

摘要: Soil remediation is of increasing importance globally, especially in developing countries. Among available remediation options, stabilization, which aims to immobilize contaminants within soil, has considerable advantages, including that it is cost-effective, versatile, sustainable, rapid, and often results in less secondary pollution. However, there are emerging challenges regarding the long-term performance of the technology, which may be affected by a range of environmental factors. These challenges stem from a research gap regarding the development of accurate, quantitative laboratory simulations of long-term conditions, whereby laboratory accelerated aging methods could be normalized to real field conditions. Therefore, field trials coupled with long-term monitoring are critical to further verify conditions under which stabilization is effective. Sustainability is also an important factor affecting the long-term stability of site remediation. It is hence important to consider these challenges to develop an optimized application of stabilization technology in soil remediation.

关键词: Stabilization     Soil remediation     Long-term     Trace metals    

Long-term exposure to air pollution and cerebrovascular disease: findings from Beijing Health Management

《环境科学与工程前沿(英文)》 2023年 第17卷 第7期 doi: 10.1007/s11783-023-1684-2

摘要:

● This study explored the long-term association by double robust additive models.

关键词: Air pollution     Cerebrovascular disease     Incidence     Long-term exposure     Doubly robust additive model    

A rate-dependent Prandtl-Ishlinskii model for piezoelectric actuators using the dynamic envelope function

Meiju YANG,Chunxia LI,Guoying GU,Limin ZHU

《机械工程前沿(英文)》 2015年 第10卷 第1期   页码 37-42 doi: 10.1007/s11465-015-0326-1

摘要:

In this paper, a novel rate-dependent Prandtl-Ishlinskii (P-I) model is proposed to characterize the rate-dependent hysteresis nonlinearity of piezoelectric actuators. The new model is based on a modified rate-dependent play operator, in which a dynamic envelope function is introduced to replace the input function of the classical play operator. Moreover, a dynamic density function is utilized in the proposed P-I model. The parameters of the proposed model are identified by a modified particle swarm optimization algorithm. Finally, experiments are conducted on a piezo-actuated nanopositioning stage to validate the proposed P-I model under the sinusoidal inputs. The experimental results show that the developed rate-dependent P-I model precisely characterize the rate-dependent hysteresis loops up to 1000 Hz.

关键词: piezoelectric actuators     hysteresis     Prandtl-Ishlinskii     rate-dependent    

Numerical analysis of vehicle-bridge coupling vibration concerning nonlinear stress-dependent damping

Pengfei LI; Jinquan ZHANG; Shengqi MEI; Zhenhua DONG; Yan MAO

《结构与土木工程前沿(英文)》 2022年 第16卷 第2期   页码 239-249 doi: 10.1007/s11709-021-0804-y

摘要: Damping is known to have a considerable influence on the dynamic behavior of bridges. The fixed damping ratios recommended in design codes do not necessarily represent the complicated damping characteristics of bridge structures. This study investigated the application of stress-dependent damping associated with vehicle-bridge coupling vibration and based on that investigation proposed the stress-dependent damping ratio. The results of the investigation show that the stress-dependent damping ratio is significantly different from the constant damping ratio (5%) defined in the standard specification. When vehicles travel at speeds of 30, 60, and 90, the damping ratios of the bridge model are 3.656%, 3.658%, and 3.671%, respectively. The peak accelerations using the regular damping ratio are 18.9%, 21.3%, and 14.5% of the stress-dependent damping ratio, respectively. When the vehicle load on the bridge is doubled, the peak acceleration of the mid-span node increases by 5.4 times, and the stress-related damping ratio increases by 2.1%. A corrugated steel-web bridge is being used as a case study, and the vibration response of the bridge is compared with the measured results. The acceleration response of the bridge which was calculated using the stress-dependent damping ratio is significantly closer to the measured acceleration response than that using the regular damping ratio.

关键词: vehicle-bridge vibration system     dynamic analysis     stress-dependent damping     energy dissipation    

Time-dependent metabolomics uncover dynamic metabolic adaptions in MCF-7 cells exposed to bisphenol A

《环境科学与工程前沿(英文)》 2023年 第17卷 第1期 doi: 10.1007/s11783-023-1604-5

摘要:

● Metabolomic temporal profiling of cells exposed to xenobiotics.

关键词: Metabolomics     BPA     MCF-7     Temporal profiling     Metabolic adaption     Dysregulation correlation    

THAI experimental research on hydrogen risk and source term related safety systems

《能源前沿(英文)》 2021年 第15卷 第4期   页码 887-915 doi: 10.1007/s11708-021-0789-1

摘要: In the defense-in-depth concept employed for the safety of nuclear installations, maintaining integrity of containment as the last barrier is of high importance to limit the release of radioactivity to the environment in case of a severe accident. The active and passive safety systems implemented in containments of light water reactors (LWRs) are designed to limit the consequences of such accidents. Assessing the performance and reliability of such systems under accident conditions is critical to the safety of nuclear installations.

关键词: severe accident     containment     safety     mitigation     H2 risk     source term    

A hybrid Wavelet-CNN-LSTM deep learning model for short-term urban water demand forecasting

《环境科学与工程前沿(英文)》 2023年 第17卷 第2期 doi: 10.1007/s11783-023-1622-3

摘要:

● A novel deep learning framework for short-term water demand forecasting.

关键词: Short-term water demand forecasting     Long-short term memory neural network     Convolutional Neural Network     Wavelet multi-resolution analysis     Data-driven models    

China’s carbon neutrality: an extensive and profound systemic reform

《环境科学与工程前沿(英文)》 2023年 第17卷 第2期 doi: 10.1007/s11783-023-1614-3

摘要:

● China has pledged ambitious carbon peak and neutrality goals for mitigating global climate change.

关键词: Carbon neutrality     Energy structure     Technology-dependent society     Coordinated mitigation for air pollutants and CO2    

Modeling temperature and moisture dependent emissions of carbon dioxide and methane from drying dairy

Enzhu HU, Pakorn SUTITARNNONTR, Markus TULLER, Scott B. JONES

《农业科学与工程前沿(英文)》 2018年 第5卷 第2期   页码 280-286 doi: 10.15302/J-FASE-2018215

摘要: Greenhouse gas emissions due to biological degradation processes of animal wastes are significant sources of air pollution from agricultural areas. The major environmental controls on these microbe-induced gas fluxes are temperature and moisture content. The objective of this study was to model the effects of temperature and moisture content on emissions of CO and CH during the ambient drying process of dairy manure under controlled conditions. Gas emissions were continuously recorded over 15 d with paired fully automated closed dynamic chambers coupled with a Fourier Transformed Infrared gas analyzer. Water content and temperature were measured and monitored with capacitance sensors. In addition, on days 0, 3, 6, 9, 12 and 15, pH, moisture content, dissolved organic carbon and total carbon (TC) were determined. An empirical model derived from the Arrhenius equation confirmed high dependency of carbon emissions on temperature and moisture content. Results indicate that for the investigated dairy manure, 6.83% of TC was lost in the form of CO and 0.047% of TC was emitted as CH . Neglecting the effect of temperature, the moisture contents associated with maximum gas emissions were estimated as 0.75 and 0.79 g·g for CO and CH , respectively.

关键词: carbon dioxide     dairy manure     methane     moisture     temperature    

标题 作者 时间 类型 操作

Reduction kinetics of SrFeO/CaO∙MnO nanocomposite as effective oxygen carrier for chemical looping partial oxidation of methane

期刊论文

Urotensin II receptor antagonist reduces hepatic resistance and portal pressure through enhanced eNOS-dependent

Ruoxi Zhang, Jing Chen, Diangang Liu, Yu Wang

期刊论文

Data-driven approach to solve vertical drain under time-dependent loading

期刊论文

Chloride binding and time-dependent surface chloride content models for fly ash concrete

S. MUTHULINGAM,B. N. RAO

期刊论文

GDF15 negatively regulates chemosensitivity via TGFBR2-AKT pathway-dependent metabolism in esophageal

期刊论文

Analysis of dispatching rules in a stochastic dynamic job shop manufacturing system with sequence-dependent

Pankaj SHARMA,Ajai JAIN

期刊论文

Stabilization-based soil remediation should consider long-term challenges

Zhengtao Shen, Zhen Li, Daniel S. Alessi

期刊论文

Long-term exposure to air pollution and cerebrovascular disease: findings from Beijing Health Management

期刊论文

A rate-dependent Prandtl-Ishlinskii model for piezoelectric actuators using the dynamic envelope function

Meiju YANG,Chunxia LI,Guoying GU,Limin ZHU

期刊论文

Numerical analysis of vehicle-bridge coupling vibration concerning nonlinear stress-dependent damping

Pengfei LI; Jinquan ZHANG; Shengqi MEI; Zhenhua DONG; Yan MAO

期刊论文

Time-dependent metabolomics uncover dynamic metabolic adaptions in MCF-7 cells exposed to bisphenol A

期刊论文

THAI experimental research on hydrogen risk and source term related safety systems

期刊论文

A hybrid Wavelet-CNN-LSTM deep learning model for short-term urban water demand forecasting

期刊论文

China’s carbon neutrality: an extensive and profound systemic reform

期刊论文

Modeling temperature and moisture dependent emissions of carbon dioxide and methane from drying dairy

Enzhu HU, Pakorn SUTITARNNONTR, Markus TULLER, Scott B. JONES

期刊论文