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Experimental investigation on freeze−thaw durability of polymer concrete

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 1038-1046 doi: 10.1007/s11709-021-0748-2

摘要： Assessing the durability of concrete is of prime importance to provide an adequate service life and reduce the repairing cost of structures. Freeze–thaw is one such test that indicates the ability of concrete to last a long time without a significant loss in its performance. In this study, the freeze–thaw resistance of polymer concrete containing different polymer contents was explored and compared to various conventional cement concretes. Concretes’ fresh and hardened properties were assessed for their workability, air content, and compressive strength. The mass loss, length change, dynamic modulus of elasticity, and residual compressive strength were determined for all types of concretes subjected to freeze–thaw cycles according to ASTM C666-procedure A. Results showed that polymer concrete (PC) specimens prepared with higher dosages of polymer contents possessed better freeze–thaw durability compared to other specimens. This high durability performance of PCs is mainly due to their impermeable microstructures, absence of water in their structure, and the high bond strength between aggregates and a polymer binder. It is also indicated that the performance of high-strength concrete containing air-entraining admixture is comparable with PC having optimum polymer content in terms of residual compressive strength, dynamic modulus of elasticity, mass loss, and length change.

关键词： durability test     freeze-thaw resistance     polymer concrete     residual compressive strength     ASTM C666-15    

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Stress-strain relationship of concrete in freeze-thaw environment

ZOU Chaoying, ZHAO Juan, LIANG Feng

《结构与土木工程前沿（英文）》 2008年 第2卷 第2期   页码 184-188 doi: 10.1007/s11709-008-0029-3

摘要： Adopting the ASTM C666 quick freeze-thaw method, freeze-thaw tests with the number of freeze-thaw cycles being 0, 100, 150, 200, 250, and 300, were carried out on eighteen concrete prism specimens, the frost-resistant level of which, reaches D300 grade. The internal micro-structures of these specimens were observed by means of scanning electron microscopy (SEM) in order to detect damages caused by the freeze-thaw action. Afterwards these frozen-thawed specimens were tested on monotonic axial load; stress-strain testing curves after the freeze-thaw action were obtained. The testing results show that with the increasing time of freeze-thaw cycles, both the internal micro-structures and the basic mechanical parameters, including the ultimate bearing capacity, the Poisson ratio and the modulus of elasticity, degenerate in various degrees. Finally, stress-strain theoretical curvilinear equations and correlated parameters relating to the loss of relative dynamic modulus of elasticity were proposed. These results provide great reference for further research on the behavior and the calculation model of concrete structures in a freeze-thaw environment.

关键词： stress-strain theoretical     freeze-thaw     capacity     reference     eighteen concrete    

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Investigation on the freeze-thaw damage to the jointed plain concrete pavement under different climate

Shuaicheng GUO, Qingli DAI, Jacob HILLER

《结构与土木工程前沿（英文）》 2018年 第12卷 第2期   页码 227-238 doi: 10.1007/s11709-017-0426-6

摘要： Freeze-thaw damage is one of the main threats to the long time performance of the concrete pavement in the cold regions. This project aims to evaluate the influence of the freeze-thaw damages on pavement distresses under different climate conditions. Based on the Long-Term Pavement Performance (LTPP) data base, the freeze-thaw damage generated by four different kinds of climate conditions are considered in this project: wet-freeze, wet-non freeze, dry-freeze and dry-non freeze. The amount of the transverse crack and the joint spalling, along with the International Roughness Index ( ) are compared among the test sections located in these four different climate conditions. The back calculation with the Falling Weight Deflectometer (FWD) test results based on the ERES and the Estimation of Concrete Pavement Parameters (ECOPP) methods are conducted to obtain concrete slab elastic modulus and the subgrade -value. These two parameters both decrease with service time under freeze condition. Finally, MEPDG simulation is conducted to simulate the development with service year. These results showed the reasonable freeze-thaw damage development with pavement service life and under different climate conditions.

关键词： LTPP     elastic modulus     k-value     IRI     MEPDG    

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Influence of construction-induced damage on the degradation of freeze–thawed lightweight cellular concrete

《结构与土木工程前沿（英文）》 2021年 第15卷 第3期   页码 781-792 doi: 10.1007/s11709-021-0733-9

摘要： During the construction of lightweight cellular concrete (LCC), material damage frequently occurs, causing the degradation and deterioration of the mechanical performance, durability, and subgrade quality of LCC. The construction-induced damage can be more significant than those from the service environment of LCC, such as freeze–thaw (F–T) action in cold regions. However, the effect of construction-induced damage on LCC during F–T cycles is often ignored and the deterioration mechanisms are not yet clarified. In this study, we investigated the factors causing damage during construction using a sample preparation method established to simulate the damage in the laboratory setting. We conducted F–T cycle tests and microstructural characterization to study the effect of microstructural damage on the overall strength of LCC with different water contents under F–T actions. We established the relationship between the pore-area ratio and F–T cycle times, pore-area ratio, and strength, as well as the F–T cycle times and strength under different damage forms. The damage evolution is provided with the rationality of the damage equation, verified by comparing the measured and predicted damage variables. This study would serve as a guide for the construction and performance of LCC in cold regions.

关键词： lightweight cellular concrete     construction-induced damage     freeze-thaw action     microstructure     degradation mechanism    

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emissions evaluation of the dynamic splitting tensile properties of steel fiber reinforced concrete under freeze–thaw

《结构与土木工程前沿（英文）》   页码 1341-1356 doi: 10.1007/s11709-023-0988-4

摘要： This study empirically investigated the influence of freeze–thaw cycling on the dynamic splitting tensile properties of steel fiber reinforced concrete (SFRC). Brazilian disc splitting tests were conducted using four loading rates (0.002, 0.02, 0.2, and 2 mm/s) on specimens with four steel fiber contents (0%, 0.6%, 1.2%, and 1.8%) subjected to 0 and 50 freeze–thaw cycles. The dynamic splitting tensile damage characteristics were evaluated using acoustic emission (AE) parameter analysis and Fourier transform spectral analysis. The results quantified using the freeze–thaw damage factor defined in this paper indicate that the degree of damage to SFRC caused by freeze–thaw cycling was aggravated with increasing loading rate but mitigated by increasing fiber content. The percentage of low-frequency AE signals produced by the SFRC specimens during loading decreased with increasing loading rate, whereas that of high-frequency AE signals increased. Freeze–thaw action had little effect on the crack types observed during the early and middle stages of the loading process; however, the primary crack type observed during the later stage of loading changed from shear to tensile after the SFRC specimens were subjected to freeze–thaw cycling. Notably, the results of this study indicate that the freeze–thaw damage to SFRC reduces AE signal activity at low frequencies.

关键词： steel fiber reinforced concrete     freeze–thaw cycling     Brazilian disc splitting test     acoustic emission technique     dynamic splitting tensile acoustic emission properties    

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Influence of freeze–thaw damage gradient on stress–strain relationship of stressed concrete

《结构与土木工程前沿（英文）》   页码 1326-1340 doi: 10.1007/s11709-023-0014-x

摘要： Influence of freeze–thaw damage gradient on stress–strain relationship of stressed concrete

关键词： strain relationship concrete    

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Biosorption of Cr(III) from aqueous solution by freeze-dried activated sludge: Equilibrium, kinetic and

Qian YAO, Hua ZHANG, Jun WU, Liming SHAO, Pinjing HE,

《环境科学与工程前沿（英文）》 2010年 第4卷 第3期   页码 286-294 doi: 10.1007/s11783-010-0025-4

摘要： Batch biosorption experiments were conducted to remove Cr(III) from aqueous solutions using activated sludge from a sewage treatment plant. An investigation was conducted on the effects of the initial pH, contact time, temperature, and initial Cr(III) concentration in the biosorption process. The results revealed that the activated sludge exhibited the highest Cr(III) uptake capacity (120 mg·g) at 45°C, initial pH of 4, and initial Cr(III) concentration of 100 mg·L. The biosorption results obtained at various temperatures showed that the biosorption pattern accurately followed the Langmuir model. The calculated thermodynamic parameters, Δ (−0.8– −4.58 kJ·mol), Δ (15.6–44.4 kJ·mol), and Δ (0.06–0.15 kJ·mol·K) clearly indicated that the biosorption process was feasible, spontaneous, endothermic, and physical. The pseudo first-order and second-order kinetic models were adopted to describe the experimental data, which revealed that the Cr(III) biosorption process conformed to the second-order rate expression and the biosorption rate constants decreased with increasing Cr(III) concentration. The analysis of the values of biosorption activation energy ( = −7 kJ·mol) and the intra-particle diffusion model demonstrated that Cr(III) biosorption was film-diffusion-controlled.

关键词： activated sludge     biosorption     chromium     film diffusion     kinetics     thermodynamics    

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Intracellular trehalose improves the survival of human red blood cells by freeze-drying

HE Hui, LIU Baolin, HUA Zezhao, LI Chuan, WU Zhengzheng

《能源前沿（英文）》 2007年 第1卷 第1期   页码 120-124 doi: 10.1007/s11708-007-0014-x

摘要： Freeze-drying of human red blood cells has a potential important application for blood transfusion. The aim of this study was to investigate the effects of intracellular trehalose on the survival of red blood cells after freeze-drying and rehydration. Fresh red blood cells were incubated in trehalose solutions of various concentrations at 37vH for 7 h following freeze-drying. Polyvinylpyrrolidone, Trehalose, sodium citrate, and human serum albumin were used as extracellular protective agents for the freeze-drying of red blood cells. The results indicated that the intracellular trehalose concentration was increased with increasing concentration of extracellular trehalose solution, and the maximum concentration of intracellular trehalose reached 35 mmol/L. The viability of freeze-dried red blood cells increased with the increment of intracellular trehalose concentration.
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具有聚集诱导发光活性的抗冻水凝胶用于低温环境下多级信息的加密和解密 Article

睢晓洁, 汪晓东, 蔡诚诚, 马君怡, 杨静, 张雷

《工程（英文）》 2023年 第23卷 第4期   页码 82-89 doi: 10.1016/j.eng.2022.03.021

摘要：

抗冻水凝胶可以在零下温度环境中调节内部水分子的冻结行为，从而保持其优异特性（如智能响应性和液体运输）以及拓展其在寒冷条件下的应用。本文开发了一系列具有聚集诱导发光（AIE）活性的抗冻水凝胶，可实现在零下温度的信息加密和解密。通过改变水凝胶内的甜菜碱含量，该水凝胶可呈现出不同的冻结温度（Tf）。当温度高于/低于Tf时，编码于水凝胶内的AIE荧光分子不发射/发射荧光，从而可以实现信息的加密和解密。此外，通过调控水凝胶的冻结程序或者在水凝胶内原位引入具有光热效应的硫化铜纳米颗粒并结合特定的照射条件，可以实现信息的多级加密和解密，从而增强信息的安全性。最后，由于解密的信息图案对温度波动具有不可逆性，因此该具有AIE活性的抗冻水凝胶可作为无需外界供能的防伪标签，用于实时和可视化监测冷冻运输（−80 ℃）过程中生物样本（如间充质干细胞和红细胞）的活性。

关键词： 抗冻水凝胶     聚集诱导发光     加密     解密     防伪    

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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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Fabrication of cellulose aerogel from wheat straw with strong absorptive capacity

Jian LI,Caichao WAN,Yun LU,Qingfeng SUN

《农业科学与工程前沿（英文）》 2014年 第1卷 第1期   页码 46-52 doi: 10.15302/J-FASE-2014004

摘要： An effectively mild solvent solution containing NaOH/PEG was employed to dissolve the cellulose extracted from the wheat straw. With further combined regeneration process and freeze-drying, the cellulose aerogel was successfully obtained. Scanning electron microscope, X-ray diffraction technique, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller were used to characterize this cellulose aerogel of low density (about 40 mg·cm ) and three-dimensional network with large specific surface area (about 101 m ·g ). Additionally, with a hydrophobic modification by trimethylchlorosilane, the cellulose aerogel showed a strong absorptive capacity for oil and dye solutions.

关键词： cellulose aerogel     absorptive capacity     waste wheat straw     freeze-drying    

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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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标题 作者 时间 类型 操作

Experimental investigation on freeze−thaw durability of polymer concrete

期刊论文

Stress-strain relationship of concrete in freeze-thaw environment

ZOU Chaoying, ZHAO Juan, LIANG Feng

期刊论文

Investigation on the freeze-thaw damage to the jointed plain concrete pavement under different climate

Shuaicheng GUO, Qingli DAI, Jacob HILLER

期刊论文

Influence of construction-induced damage on the degradation of freeze–thawed lightweight cellular concrete

期刊论文

emissions evaluation of the dynamic splitting tensile properties of steel fiber reinforced concrete under freeze–thaw

期刊论文

Influence of freeze–thaw damage gradient on stress–strain relationship of stressed concrete

期刊论文

Biosorption of Cr(III) from aqueous solution by freeze-dried activated sludge: Equilibrium, kinetic and

Qian YAO, Hua ZHANG, Jun WU, Liming SHAO, Pinjing HE,

期刊论文

Intracellular trehalose improves the survival of human red blood cells by freeze-drying

HE Hui, LIU Baolin, HUA Zezhao, LI Chuan, WU Zhengzheng

期刊论文

具有聚集诱导发光活性的抗冻水凝胶用于低温环境下多级信息的加密和解密

睢晓洁, 汪晓东, 蔡诚诚, 马君怡, 杨静, 张雷

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

Fabrication of cellulose aerogel from wheat straw with strong absorptive capacity

Jian LI,Caichao WAN,Yun LU,Qingfeng SUN

期刊论文

Transmission of antibiotic resistance genes in agroecosystems: an overview

Jizheng HE, Zhenzhen YAN, Qinglin CHEN

期刊论文