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Simplified theoretical analysis and numerical study on the dynamic behavior of FCP under blast loads

Chunfeng ZHAO, Xin YE, Avinash GAUTAM, Xin LU, Y. L. MO

《结构与土木工程前沿（英文）》 2020年 第14卷 第4期   页码 983-997 doi: 10.1007/s11709-020-0633-4

摘要： Precast concrete structures have developed rapidly in the last decades due to the advantages of better quality, non-pollution and fast construction with respect to conventional cast-in-place structures. In the present study, a theoretical model and nonlinear 3D model are developed and established to assess the dynamic behavior of precast concrete slabs under blast load. At first, the 3D model is validated by an experiment performed by other researchers. The verified model is adopted to investigate the blast performance of fabricated concrete panels (FCPs) in terms of parameters of the explosive charge, panel thickness, and reinforcement ratio. Finally, a simplified theoretical model of the FCP under blast load is developed to predict the maximum deflection. It is indicated that the theoretical model can precisely predict the maximum displacement of FCP under blast loads. The results show that the failure modes of the panels varied from bending failure to shear failure with the mass of TNT increasing. The thickness of the panel, reinforcement ratio, and explosive charges have significant effects on the anti-blast capacity of the FCPs.

关键词： precast structure     fabricated concrete panel     blast resistance     theory model     empirical equation    

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Performance of soft-hard-soft (SHS) cement based composite subjected to blast loading with consideration

Jun WU,Xuemei LIU

《结构与土木工程前沿（英文）》 2015年 第9卷 第3期   页码 323-340 doi: 10.1007/s11709-015-0301-2

摘要： This paper presents a combined experimental and numerical study on the damage and performance of a soft-hard-soft (SHS) multi-layer cement based composite subjected to blast loading which can be used for protective structures and infrastructures to resist extreme loadings, and the composite consists of three layers of construction materials including asphalt concrete (AC) on the top, high strength concrete (HSC) in the middle, and engineered cementitious composites (ECC) at the bottom. To better characterize the material properties under dynamic loading, interface properties of the composite were investigated through direct shear test and also used to validate the interface model. Strain rate effects of the asphalt concrete were also studied and both compressive and tensile dynamic increase factor (DIF) curves were improved based on split Hopkinson pressure bar (SHPB) test. A full-scale field blast test investigated the blast behavior of the composite materials. The numerical model was established by taking into account the strain rate effect of all concrete materials. Furthermore, the interface properties were also considered into the model. The numerical simulation using nonlinear finite element software LS-DYNA agrees closely with the experimental data. Both the numerical and field blast test indicated that the SHS composite exhibited high resistance against blast loading.

关键词： high strength concrete (SHS)     engineered cementitious composite     interface     blast test     strain rate effect    

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Development of dimensionless P-I diagram for curved SCS sandwich shell subjected to uniformly distributed blast

Yonghui WANG, Ximei ZHAI

《结构与土木工程前沿（英文）》 2019年 第13卷 第6期   页码 1432-1445 doi: 10.1007/s11709-019-0566-y

摘要： The curved steel-concrete-steel (SCS) sandwich shell was recently proposed to resist blast loading and it showed better blast resistant performance as compared to flat SCS sandwich shell via developing compressive force along the shell. In this paper, a dimensionless Pressure-Impulse (P-I) diagram was constructed as a convenient tool to predict the damage level of curved SCS sandwich shell subjected to uniformly distributed blast loading. The curved SCS sandwich shell was equivalent to a single-degree-of-freedom (SDOF) system and the equation of motion was established by employing the Lagrange’s equation. To construct the dimensionless P-I diagram, the energy balance method was utilized to yield the pressure and impulse asymptotes and the responses in the dynamic response regime were obtained via employing the SDOF method. Then, the finite element method was employed to validate the developed dimensionless P-I diagram. Finally, the procedures of using the constructed dimensionless P-I diagram to quickly conduct the blast resistant design of curved SCS sandwich shell were presented.

关键词： blast loading     curved steel-concrete-steel sandwich shell     Pressure-Impulse diagram     single-degree-of-freedom method     finite element analysis    

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Simulation of blast induced crater in jointed rock mass by discontinuous deformation analysis method

Youjun NING, Xinmei AN, Jun YANG, Guowei MA,

《结构与土木工程前沿（英文）》 2010年 第4卷 第2期   页码 223-232 doi: 10.1007/s11709-010-0022-5

摘要： Rock blasting is a dynamic process accompanied with the propagations of shock waves and the dispersion of the explosion gas. This paper adopts the discontinuous deformation analysis (DDA) method to simulate the rock blasting process. A dynamic parameter adjustment and the non-reflecting boundary condition are implemented in the DDA method. The sub-block DDA method to simulate fracture problems is used. The blasting process in jointed rock mass is simulated by application of the explosion gas pressure on the expanding borehole walls and induced connected fracture surfaces around the boreholes. The blast craters with different overburdens are derived. The whole process including the explosion gas dispersion, borehole expansion, rock mass failure and cast, and the formation of the final blasting piles in rock blasting are well reproduced numerically. Parametric study for different overburdens is carried out, and the results are analyzed and discussed.

关键词： blast crater     jointed rock mass     explosion gas pressure     discontinuous deformation analysis (DDA) method    

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Prediction of characteristic blast-induced vibration frequency during underground excavation by using

Tae Un PAK; Guk Rae JO; Un Chol HAN

《结构与土木工程前沿（英文）》 2022年 第16卷 第8期   页码 1029-1039 doi: 10.1007/s11709-022-0861-x

摘要： Blast-induced vibration produces a very complex signal, and it is very important to work out environmental problems induced by blasting. In this study, blasting vibration signals were measured during underground excavation in carbonaceous shale by using vibration pickup CB-30 and FFT analyzer AD-3523. Then, wavelet analysis on the measured results was carried out to identify frequency bands reflecting changes of blasting vibration parameters such as vibration velocity and energy in different frequency bands. Frequency characteristics are then discussed in view of blast source distance and charge weight per delay. From analysis of results, it can be found that peak velocity and energy of blasting vibration in frequency band of 62.5–125 Hz were larger than ones in other bands, indicating the similarity to characteristics in the distribution band (31–130 Hz) of main vibration frequency. Most frequency bands were affected by blasting source distance, and the frequency band of 0–62.5 Hz reflected the change of charge weight per delay. By presenting a simplified method to predict main vibration frequency, this research may provide significant reference for future blasting engineering.

关键词： wavelet analysis     blast-induced vibration     frequency characteristics     underground excavation    

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Dynamic failure analysis of concrete dams under air blast using coupled Euler-Lagrange finite element

Farhoud KALATEH

《结构与土木工程前沿（英文）》 2019年 第13卷 第1期   页码 15-37 doi: 10.1007/s11709-018-0465-7

摘要： In this study, the air blast response of the concrete dams including dam-reservoir interaction and acoustic cavitation in the reservoir is investigated. The finite element (FE) developed code are used to build three-dimensional (3D) finite element models of concrete dams. A fully coupled Euler-Lagrange formulation has been adopted herein. A previous developed model including the strain rate effects is employed to model the concrete material behavior subjected to blast loading. In addition, a one-fluid cavitating model is employed for the simulation of acoustic cavitation in the fluid domain. A parametric study is conducted to evaluate the effects of the air blast loading on the response of concrete dam systems. Hence, the analyses are performed for different heights of dam and different values of the charge distance from the charge center. Numerical results revealed that 1) concrete arch dams are more vulnerable to air blast loading than concrete gravity dams; 2) reservoir has mitigation effect on the response of concrete dams; 3) acoustic cavitation intensify crest displacement of concrete dams.

关键词： air blast loading     concrete dams     finite element     dam-reservoir interaction     cavitation     concrete damage model    

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Extension of pilot tests of cyanide elimination by ozone from blast furnace gas washing water through

Ismael Matino, Valentina Colla, Teresa A. Branca

《化学科学与工程前沿（英文）》 2018年 第12卷 第4期   页码 718-730 doi: 10.1007/s11705-018-1771-2

摘要：

For improving wastewater quality, one of the dare of steelworks is reducing cyanide in wastewater of gas washing treatment of blast furnaces. Costs of existing treatments, stringent environmental regulations and changeable composition of water from gas treatment, have led to study how available treatments can be modified and to examine new ones. Ozonation is one of cyanide treatments, tested within a European project. A process model was set up with Aspen Plus®, to assess operating conditions and wastewater distinctive characteristics and to demonstrate treatment robustness. Process was modeled by theoretical reactors, taking into account all more affecting reactions. A genetic algorithm was exploited to find kinetic parameters of these reactions. After validation, the model was used to analyse scenarios, by considering also real contexts. Pilot tests were extended, process knowledge was enhanced and suggestions were obtained. To promote cyanide removal with ozone, temperature and pH values were 30°C and 10, respectively. With an ozone (mg/h)/water (L/h) ratio of 100 mg/L, batch mode ensure reaching cyanide regulation limit (0.2 mg/L) after maximum 4.5 h, if initial amount was less than 20 mg/L. Higher removal was obtained than in continuous mode due to constraints related to this last run. Higher wastewater contamination needed further time and more ozone.

关键词： blast furnace     cyanide removal     gas washing water     modeling and simulation     ozonation    

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Prevalence of antifolate drug resistance markers in in China

《医学前沿（英文）》 2022年 第16卷 第1期   页码 83-92 doi: 10.1007/s11684-021-0894-x

摘要： The dihydrofolate reductase (dhfr) and dihydropteroate synthetase (dhps) genes of Plasmodium vivax and antifolate resistance-associated genes were used for drug resistance surveillance. A total of 375 P. vivax isolates collected from different geographical locations in China in 2009–2019 were used to sequence Pvdhfr and Pvdhps. The majority of the isolates harbored a mutant type allele for Pvdhfr (94.5%) and Pvdhps (68.2%). The most predominant point mutations were S117T/N (77.7%) in Pvdhfr and A383G (66.8%) in Pvdhps. Amino acid changes were identified at nine residues in Pvdhfr. A quadruple-mutant haplotype at 57, 58, 61, and 117 was the most frequent (57.4%) among 16 distinct Pvdhfr haplotypes. Mutations in Pvdhps were detected at six codons, and the double-mutant A383G/A553G was the most prevalent (39.3%). Pvdhfr exhibited a higher mutation prevalence and greater diversity than Pvdhps in China. Most isolates from Yunnan carried multiple mutant haplotypes, while the majority of samples from temperate regions and Hainan Island harbored the wild type or single mutant type. This study indicated that the antifolate resistance levels of P. vivax parasites were different across China and molecular markers could be used to rapidly monitor drug resistance. Results provided evidence for updating national drug policy and treatment guidelines.

关键词： drug resistance     antifolates     molecular markers     Plasmodium vivax     China    

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Metagenomic analysis on resistance genes in water and microplastics from a mariculture system

《环境科学与工程前沿（英文）》 2022年 第16卷 第1期   页码 4-4 doi: 10.1007/s11783-021-1438-y

摘要：

Microplastics existing widely in different matrices have been regarded as a reservoir for emerging contaminants. Mariculture systems have been observed to host microplastics and antibiotic resistance genes (ARGs). However, more information on proliferation of ARGs and metal resistance genes (MRGs) in mariculture system at the presence of microplastics is needed.

关键词： Antibiotic resistance genes     Metal resistance genes     Metagenomic analysis     Microplastics     Mariculture    

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Taking advantage of drug resistance, a new approach in the war on cancer

null

《医学前沿（英文）》 2018年 第12卷 第4期   页码 490-495 doi: 10.1007/s11684-018-0647-7

摘要：

Identification of the driver mutations in cancer has resulted in the development of a new category of molecularly targeted anti-cancer drugs. However, as was the case with conventional chemotherapies, the effectiveness of these drugs is limited by the emergence of drug-resistant variants. While most cancer therapies are given in combinations that are designed to avoid drug resistance, we discuss here therapeutic approaches that take advantage of the changes in cancer cells that arise upon development of drug resistance. This approach is based on notion that drug resistance comes at a fitness cost to the cancer cell that can be exploited for therapeutic benefit. We discuss the development of sequential drug therapies in which the first therapy is not given with curative intent, but to induce a major new sensitivity that can be targeted with a second drug that selectively targets the acquired vulnerability. This concept of collateral sensitivity has hitherto not been used on a large scale in the clinic and holds great promise for future cancer therapy.

关键词： cancer     drug resistance     genetic screens     senescence     targeted therapy    

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Targeting apoptosis to manage acquired resistance to third generation EGFR inhibitors

《医学前沿（英文）》 2022年 第16卷 第5期   页码 701-713 doi: 10.1007/s11684-022-0951-0

摘要： A significant clinical challenge in lung cancer treatment is management of the inevitable acquired resistance to third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (EGFR-TKIs), such as osimertinib, which have shown remarkable success in the treatment of advanced NSCLC with EGFR activating mutations, in order to achieve maximal response duration or treatment remission. Apoptosis is a major type of programmed cell death tightly associated with cancer development and treatment. Evasion of apoptosis is considered a key hallmark of cancer and acquisition of apoptosis resistance is accordingly a key mechanism of drug acquired resistance in cancer therapy. It has been clearly shown that effective induction of apoptosis is a key mechanism for third generation EGFR-TKIs, particularly osimertinib, to exert their therapeutic efficacies and the development of resistance to apoptosis is tightly associated with the emergence of acquired resistance. Hence, restoration of cell sensitivity to undergo apoptosis using various means promises an effective strategy for the management of acquired resistance to third generation EGFR-TKIs.

关键词： acquired resistance     EGFR inhibitor     apoptosis     lung cancer    

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Transmission of antibiotic resistance genes in agroecosystems: an overview

Jizheng HE, Zhenzhen YAN, Qinglin CHEN

《农业科学与工程前沿（英文）》 2020年 第7卷 第3期   页码 329-332 doi: 10.15302/J-FASE-2020333

摘要：

The use of antibiotics in human medicine and animal husbandry has resulted in the continuous release of antibiotics into the environment, which imposes high selection pressure on bacteria to develop antibiotic resistance. The spread and aggregation of antibiotic resistance genes (ARGs) in multidrug-resistant pathogens is one of the most intractable clinical challenges. Numerous studies have been conducted to profile the patterns of ARGs in agricultural ecosystems, as this is closely related to human health and wellbeing. This paper provides an overview of the transmission of ARGs in agricultural ecosystems resulting from the application of animal manures and other organic amendments. The future need to control and mitigate the spread of antibiotic resistance in agricultural ecosystems is also discussed, particularly from a holistic perspective, and requires multiple sector efforts to translate fundamental knowledge into effective strategies.

关键词： agroecosystem     antibiotic resistance     public health     soil-plant system    

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swine manure with sulfamethoxazole and norfloxacin: Dynamics of microbial communities and evolution of resistance

《环境科学与工程前沿（英文）》 2021年 第15卷 第5期 doi: 10.1007/s11783-020-1342-x

摘要：

• SMX addition had negative effect on acetoclastic methanogens in mesophilic AD.

关键词： Pig manure     Antibiotics     Anaerobic digestion     Resistance genes     Microbial community    

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Degradation of extracellular genomic, plasmid DNA and specific antibiotic resistance genes by chlorination

Menglu Zhang, Sheng Chen, Xin Yu, Peter Vikesland, Amy Pruden

《环境科学与工程前沿（英文）》 2019年 第13卷 第3期 doi: 10.1007/s11783-019-1124-5

摘要：

Extracellular DNA structure damaged by chlorination was characterized.

Integrity of extracellular ARG genetic information after chlorination was determined.

Typical chlorine doses will likely effectively diminish extracellular DNA and ARGs.

Plasmid DNA/ARGs were less readily broken down than genomic DNA.

The Bioanalyzer methodology effectively documented damage incurred to DNA.

关键词： Antibiotic resistance     Antibiotic resistance genes (ARGs)     Extracellular DNA/ARGs     Chlorination    

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Insulin resistance and the metabolism of branched-chain amino acids

null

《医学前沿（英文）》 2013年 第7卷 第1期   页码 53-59 doi: 10.1007/s11684-013-0255-5

摘要：

Insulin resistance (IR) is a key pathological feature of metabolic syndrome and subsequently causes serious health problems with an increased risk of several common metabolic disorders. IR related metabolic disturbance is not restricted to carbohydrates but impacts global metabolic network. Branched-chain amino acids (BCAAs), namely valine, leucine and isoleucine, are among the nine essential amino acids, accounting for 35% of the essential amino acids in muscle proteins and 40% of the preformed amino acids required by mammals. The BCAAs are particularly responsive to the inhibitory insulin action on amino acid release by skeletal muscle and their metabolism is profoundly altered in insulin resistant conditions and/or insulin deficiency. Although increased circulating BCAA concentration in insulin resistant conditions has been noted for many years and BCAAs have been reported to be involved in the regulation of glucose homeostasis and body weight, it is only recently that BCAAs are found to be closely associated with IR. This review will focus on the recent findings on BCAAs from both epidemic and mechanistic studies.

关键词： branched-chain amino acids     leucine     isoleucine     valine     insulin resistance    

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标题 作者 时间 类型 操作

Simplified theoretical analysis and numerical study on the dynamic behavior of FCP under blast loads

Chunfeng ZHAO, Xin YE, Avinash GAUTAM, Xin LU, Y. L. MO

期刊论文

Performance of soft-hard-soft (SHS) cement based composite subjected to blast loading with consideration

Jun WU,Xuemei LIU

期刊论文

Development of dimensionless P-I diagram for curved SCS sandwich shell subjected to uniformly distributed blast

Yonghui WANG, Ximei ZHAI

期刊论文

Simulation of blast induced crater in jointed rock mass by discontinuous deformation analysis method

Youjun NING, Xinmei AN, Jun YANG, Guowei MA,

期刊论文

Prediction of characteristic blast-induced vibration frequency during underground excavation by using

Tae Un PAK; Guk Rae JO; Un Chol HAN

期刊论文

Dynamic failure analysis of concrete dams under air blast using coupled Euler-Lagrange finite element

Farhoud KALATEH

期刊论文

Extension of pilot tests of cyanide elimination by ozone from blast furnace gas washing water through

Ismael Matino, Valentina Colla, Teresa A. Branca

期刊论文

Prevalence of antifolate drug resistance markers in in China

期刊论文

Metagenomic analysis on resistance genes in water and microplastics from a mariculture system

期刊论文

Taking advantage of drug resistance, a new approach in the war on cancer

null

期刊论文

Targeting apoptosis to manage acquired resistance to third generation EGFR inhibitors

期刊论文

Transmission of antibiotic resistance genes in agroecosystems: an overview

Jizheng HE, Zhenzhen YAN, Qinglin CHEN

期刊论文

swine manure with sulfamethoxazole and norfloxacin: Dynamics of microbial communities and evolution of resistance

期刊论文

Degradation of extracellular genomic, plasmid DNA and specific antibiotic resistance genes by chlorination

Menglu Zhang, Sheng Chen, Xin Yu, Peter Vikesland, Amy Pruden

期刊论文

Insulin resistance and the metabolism of branched-chain amino acids

null

期刊论文