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Impact resistance property

Heming LIN, Dongming QI, Jian HAN, Zhiqi CAI, Minghua WU

《化学科学与工程前沿（英文）》 2009年第3卷第2期页码 176-181 doi: 10.1007/s11705-009-0203-8

摘要： A novel phenolic rigid organic filler (KT) was used to modify isotactic polypropylene (iPP). The influence of KT particles on the impact resistance property of PP/KT specimens (with similar interparticles distance, 1.8 μm) was studied by notched izod impact tests. It was found that the brittle-ductile transition (BDT) of the PP/KT microcomposites took place at the filler content of about 4%, and the impact strength attains the maximum at 5% (with filler particles size of 1.5 μm), which is about 2.5 times that of unfilled iPP specimens. The impact fracture morphology was investigated by scanning electron microscopy (SEM). For the PP/KT specimens and the high-density polyethylene/KT (HDPE/KT) specimens in ductile fracture mode, many microfibers could be found on the whole impact fracture surface. It was the filler particles that induced the plastic deformation of interparticles ligament and hence improved the capability of iPP matrix on absorbing impact energy dramatically. The determinants on the BDT were further discussed on the basis of stress concentration and debonding resistance. It can be concluded that aside from the interparticle distance, the filler particles size also plays an important role in semicrystalline polymer toughening.

关键词： rigid organic filler polypropylene impact resistance

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Mechanical properties and impact resistance of concrete composites with hybrid steel fibers

Fatih ÖZALP; Halit Dilşad YILMAZ; Burcu AKCAY

《结构与土木工程前沿（英文）》 2022年第16卷第5期页码 615-623 doi: 10.1007/s11709-022-0828-y

摘要： The aim of this study is to develop concrete composites that are resistant to armor-piercing projectiles for defense structures. Different reinforcement configurations have been tested, such as short steel fibers, long steel fibers, and steel mesh reinforcement. Three different concrete mix designs were prepared as “Ultra High Performance (UHPFRC), High Performance (HPFRC) and Conventional (CFRC) Fiber Reinforced Concrete”. The content of hybrid steel fibers was approximately 5% in the UHPFRC and HPFRC mixtures, while the steel fiber content was approximately 2.5% in the CFRC mixture. In addition, a plain state of each mixture was produced. Mechanical properties of concrete were determined in experimental studies. In addition to the fracture energy and impact strength, two important indicators of ballistic performance of concrete are examined, which are the penetration depth and damage area. The results of the study show that the depth of penetration in UHPFRC was around 35% less than that in HPFRC. It was determined that the mixtures of UHPFRC and HPFRC containing 5% by volume of hybrid steel fibers showed superior performance (smaller crater diameter and the less projectile penetration depth) against armor-piercing projectiles in ballistic tests and could be used in defense structures.

关键词： projectile impact depth of penetration fracture energy crater diameter UHPFRC

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Improvement of impact resistance of plain-woven composite by embedding superelastic shape memory alloy

Xiaojun GU, Xiuzhong SU, Jun WANG, Yingjie XU, Jihong ZHU, Weihong ZHANG

《机械工程前沿（英文）》 2020年第15卷第4期页码 547-557 doi: 10.1007/s11465-020-0595-1

摘要： Carbon fiber reinforced polymer (CFRP) composites have excellent mechanical properties, specifically, high specific stiffness and strength. However, most CFRP composites exhibit poor impact resistance. To overcome this limitation, this study presents a new plain-woven CFRP composite embedded with superelastic shape memory alloy (SMA) wires. Composite specimens are fabricated using the vacuum-assisted resin injection method. Drop-weight impact tests are conducted on composite specimens with and without SMA wires to evaluate the improvement of impact resistance. The material models of the CFRP composite and superelastic SMA wire are introduced and implemented into a finite element (FE) software by the explicit user-defined material subroutine. FE simulations of the drop-weight impact tests are performed to reveal the superelastic deformation and debonding failure of the SMA inserts. Improvement of the energy absorption capacity and toughness of the SMA-CFRP composite is confirmed by the comparison results.

关键词： carbon fiber reinforced polymer composite shape memory alloy wire impact resistance drop-weight test finite element simulation

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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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Game theoretic analysis of environmental impact assessment system in China

CHENG Hongguang, PU Xiao, GONG Li, QI Ye

《环境科学与工程前沿（英文）》 2007年第1卷第4期页码 448-453 doi: 10.1007/s11783-007-0071-8

摘要： Environmental impact assessment (EIA) system has been established in China since 1973. In present EIA cases, there are four participants in general: governments, enterprises, EIA organizations and the public. The public has held re

关键词： public impact assessment Environmental impact general

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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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The clinical impact of tricuspid regurgitation in patients with a biatrial orthotopic heart transplant

《医学前沿（英文）》 2023年第17卷第3期页码 527-533 doi: 10.1007/s11684-022-0967-5

摘要： In this study, we aim to elucidate the clinical impact and long-term course of tricuspid regurgitation (TR), taking into account its dynamic nature, after biatrial orthotopic heart transplant (OHT). All consecutive adult patients undergoing biatrial OHT (1984−2017) with an available follow-up echocardiogram were included. Mixed-models were used to model the evolution of TR. The mixed-model was inserted into a Cox model in order to address the association of the dynamic TR with mortality. In total, 572 patients were included (median age: 50 years, males: 74.9%). Approximately 32% of patients had moderate-to-severe TR immediately after surgery. However, this declined to 11% on 5 years and 9% on 10 years after surgery, adjusted for survival bias. Pre-implant mechanical support was associated with less TR during follow-up, whereas concurrent LV dysfunction was significantly associated with more TR during follow-up. Survival at 1, 5, 10, 20 years was 97% ± 1%, 88% ± 1%, 66% ± 2% and 23% ± 2%, respectively. The presence of moderate-to-severe TR during follow-up was associated with higher mortality (HR: 1.07, 95% CI (1.02–1.12), p = 0.006). The course of TR was positively correlated with the course of creatinine (R = 0.45). TR during follow-up is significantly associated with higher mortality and worse renal function. Nevertheless, probability of TR is the highest immediately after OHT and decreases thereafter. Therefore, it may be reasonable to refrain from surgical intervention for TR during earlier phase after OHT.

关键词： orthotopic heart transplant tricuspid regurgitation clinical impact biatrial heart transplantation

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Dynamical analysis of droplet impact spreading on solid substrate

Zhaomiao LIU, Huamin LIU, Xin LIU,

《机械工程前沿（英文）》 2010年第5卷第3期页码 308-315 doi: 10.1007/s11465-010-0020-2

摘要： This paper investigates the impact spreading of a droplet on a solid substrate using numerical simulation on the basis of a volume-of-fluid (VOF) model. The process of droplet spreading is described, the analysis of low speed and high speed droplet spreading, and more than one droplet spreading simultaneously is performed. The pressure, velocity, and spreading factor during the droplet spreading are reported. According to the spreading factor’s evolvement, the process of droplet spreading can be classified into spreading phase and recoiling phase. The spreading factors are almost the same at the low speed droplet spreading; however, the pressures on the substrate are quite different and air entrainment may be found as the impact speeds in a certain range. The impact speed impacts on the spreading factors in high speed droplet spreading. The spreading factor obviously increases with increasing impact speed; however, splashing will appear in the status when the speed is high enough in the high speed droplet spreading. The distance between the neighbor droplets affects the film’s quality, and only the distance between the static diameter and the maximum diameter can ensure the film’s quality. The results could help in understanding the process of droplet spreading and provide advice on the operation of a spray coating process.

关键词： droplet impact spreading numerical simulation

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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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Comparison of droplet distributions from fluidic and impact sprinklers

Xingye ZHU,Shouqi YUAN,Junping LIU,Xingfa LIU

《农业科学与工程前沿（英文）》 2015年第2卷第1期页码 53-59 doi: 10.15302/J-FASE-2015049

摘要： To adapt to the trend toward low-energy precision irrigation, the droplet distributions for two new prototype sprinklers, outside signal sprinkler (OS) and fluidic sprinkler (FS), were compared with impact sprinkler (IS). A laser precipitation monitor was used to measure the droplet distributions. Droplet size and velocity distributions were tested under four operating pressures for nozzles 1.5 m above the ground. For the operating pressures tested, the mean OS, FS and IS droplet diameters ranged from 0 to 3.4, 0 to 3.5, 0 to 4.0 mm, respectively. The mean OS and FS droplet velocities ranged from 0 to 6.3 m·s , whereas IS ranged from 0 to 6.3 m·s . Being gas-liquid fluidic sprinklers, droplet distributions of the OS and FS were similar, although not identical. IS mostly produced a 0.5 mm larger droplet diameter and a 0.5 m·s greater velocity than OS and FS. A new empirical equation is proposed for determination of droplet size for OS and FS, which is sufficiently accurate and simple to use. Basic statistics for droplet size and velocity were performed on data obtained by the photographic methods. The mean droplet diameter (arithmetic, volumetric and median) decreased and the mean velocity increased in operating pressure for the three types of sprinkler.

关键词： outside signal sprinkler fluidic sprinkler impact sprinkler sprinkler irrigation droplet size droplet velocity

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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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Hazard potential of zones of weakness in gravity dams under impact loading conditions

Herbert LINSBAUER

《结构与土木工程前沿（英文）》 2011年第5卷第1期页码 90-97 doi: 10.1007/s11709-010-0008-3

摘要： Dam constructions worldwide are designed and constructed in view of the strictest safety aspects for all static and dynamic load cases. As experience shows, however, formation of cracks in the “homogeneos concrete” as well as unsatisfactory compound behavior of lift joints are not to be excluded. These zones of weakness especially on the upstream side of the dam— exposed to high water pressure (static and dynamic)— represent an increased risk of safety. The main investigation, apart from the computation of the dynamic effects on the dam as a global structure, focuses on the stability analysis of a pressure-water filled crack configuration subjected to “dynamic loading” in the form of seismic action on the dam-reservoir-system and alternatively by “impact spot-loading” within sectors of the reservoir. A fracture mechanics based analysis shows an excessive potential of damage for the afflicted structure.

关键词： dam-reservoir earthquake impact cracking fracture mechanics

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Buffer capacity of granular matter to impact of spherical projectile based on discrete element method

Ying YAN, Pengfei LI, Shunying JI

《结构与土木工程前沿（英文）》 2013年第7卷第1期页码 50-54 doi: 10.1007/s11709-013-0186-x

摘要： Granular matter possesses impact-absorbing property due to its energy dissipation character. To investigate the impact-absorbing capacity of granular matter, the discrete element method (DEM) is adopted to simulate the impact of a spherical projectile on to a granular bed. The dynamic responses of the projectile are obtained for both thin and thick granular bed. The penetration depth of the projectile and the first impact peak are investigated with different bed thicknesses and impact velocities. Determining a suitable bed thickness is crucial to the buffering effect of granular matter. The first impact peak is independent of bed thickness when the thickness is larger than the critical thickness.

关键词： granular matter impact peak buffer capacity discrete element method critical thickness