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期刊论文 33

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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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Comparison study on strategies to prepare nanocrystalline Li

Qiang XIAO, Xiaodan TANG, Yefeng LIU, Yijun ZHONG, Weidong ZHU

《化学科学与工程前沿（英文）》 2013年 第7卷 第3期   页码 297-302 doi: 10.1007/s11705-013-1346-1

摘要： A comparison study has been conducted on the strategies for synthesizing nanocrystalline Li ZrO and K-doped Li ZrO absorbents for CO capture at high temperatures, including solid-state and liquid-phase methods, citrate route, and starch-assisted sol-gel method combined with freeze-drying technique. The absorption properties, including uptake rate and absorption capacity, of synthesized absorbents were investigated by thermogravimetric analysis (TGA) at different CO partial pressures. The nanosized Li ZrO crystals synthesized by the citrate route exhibit a faster uptake and a higher, nearly stoichiometric absorption capacity than those synthesized by the solid-state and liquid-phase methods. The doping of K into Li ZrO can significantly improve the uptake rate of CO , especially at low CO partial pressures. For the synthesis of K-doped Li ZrO , the citrate route has poor reproducibility and scalability, whereas the starch-assisted sol-gel method combined with freeze-drying technique is reproducible and easily scaled up, and the thus synthesized absorbents possess excellent CO capture properties.

关键词： CO2 capture     Li2ZrO3     K-doped Li2ZrO3     citrate     starch     freeze-drying technique    

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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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冷冻-萃取/真空干燥法制备坚固和耐疲劳的聚酰亚胺纤维气凝胶及其增强阻燃性复合材料 Article

姚恺清, 宋崇虎, 方红, 王峰, 陈炼, 蒋少华, 查国君, 侯豪情

《工程（英文）》 2023年 第21卷 第2期   页码 152-161 doi: 10.1016/j.eng.2021.08.024

摘要：

在现代新材料的快速发展中，用节能、省时、低成本和简便的新型方法制备具有优良机械性能和热学性能的轻质、低密度和高孔隙率气凝胶十分必要。在本工作中，我们使用短切电纺聚酰亚胺（PI）纤维作为支撑骨架，通过开发出一种无需特殊干燥方法的真空干燥（VD）与冷冻-萃取相结合的方法，制备出高性能PI 纤维气凝胶（PIFAs）。所得PIFAs 具有低密度（≤52.8 mg⋅cm−3）和高孔隙率（>96%）。该PIFA在至少20 000 次的循环压缩过程中展现出高度的耐疲劳性及低能量损失系数。密度为39.1 mg⋅cm−3的PIFA具有40.4 mW⋅m−1⋅K−1的热导率。通过进一步使用聚硅氮烷对PIFAs复合改性后，其具备更强的耐火性和氮气氛围中的高残留率（>70%）。这些优异的性能使PIFAs 及其复合材料成为可应用于建筑工业、航空和航天工业轻质材料、隔热和防火层以及高温反应催化剂载体的可选材料。此外，本工作中提出的冷冻-萃取/VD法因其节能、省时和节约成本而可被拓展用于制备其他材料。

关键词： 聚酰亚胺气凝胶     冷冻萃取     真空干燥     机械性能     隔热性能     防火性能    

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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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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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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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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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Soybean drying characteristics in microwave rotary dryer with forced convection

Ruifang WANG, Zhanyong LI, Yanhua LI, Jingsheng YE

《化学科学与工程前沿（英文）》 2009年 第3卷 第3期   页码 289-292 doi: 10.1007/s11705-009-0022-y

摘要： A new hybrid drying technique by combining microwave and forced convection drying within a rotary drum, i.e., microwave rotary drying, was developed with the purpose to improve the uniformity of microwave drying. In a laboratory microwave rotary dryer, rewetted soybean was utilized as experimental material to study the effects of drum rotating speed, ventilation flow rate, and specific microwave power on the drying kinetics and cracking ratio of soybean. It was found that, with rotation, the cracking ratio can be lowered but without distinct improvement in the drying rate. Increasing ventilation flow rate and specific microwave power can improve the drying rate, but the cracking ratio also increases as a negative result. The cracking ratio lower than 10% can be attained for ventilation flow rate lower than 2.0 m ·h or specific microwave energy lower than 0.4 kW·kg in the present experiments.

关键词： cracking     microwave     rotary drying     soybean    

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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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A solar assisted heat pump drying system for grain in-store drying

Haifeng LI, Yanjun DAI, Jianguo DAI, Xibo WANG, Lei WEI,

《能源前沿（英文）》 2010年 第4卷 第3期   页码 386-391 doi: 10.1007/s11708-010-0003-3

摘要： For grain in-store drying, a solar assisted drying process has been developed, which consists of a set including a solar-assisted heat pump, a ventilation system, a grain stirrer, etc. In this way, low power consumption, short cycle time and water content uniformity can be achieved in comparison with the conventional method. A solar-assisted heat pump drying system has been designed and manufactured for a practical granary, and the energy consumption performance of the unit is analyzed. The analysis result shows that the solar fraction of the unit is higher than 20%, the coefficient of performance about system (COP) is 5.19, and the specific moisture extraction rate (SMER) can reach 3.05 kg/kWh.

关键词： solar energy     heat pump     airflow     in-store drying    

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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    

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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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Effects of previous drying of sediment on root functional traits and rhizoperformance of emerged macrophytes

《环境科学与工程前沿（英文）》 2021年 第15卷 第6期 doi: 10.1007/s11783-021-1427-1

摘要：

• Sediment desiccation alters morphological characteristics of aquatic sediment.

关键词： Fibrous-root macrophytes     Thick-root macrophytes     Nutrients removal     Wet sediment     Dried-rewetted sediment    

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标题 作者 时间 类型 操作

Fabrication of cellulose aerogel from wheat straw with strong absorptive capacity

Jian LI,Caichao WAN,Yun LU,Qingfeng SUN

期刊论文

Comparison study on strategies to prepare nanocrystalline Li

Qiang XIAO, Xiaodan TANG, Yefeng LIU, Yijun ZHONG, Weidong ZHU

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

冷冻-萃取/真空干燥法制备坚固和耐疲劳的聚酰亚胺纤维气凝胶及其增强阻燃性复合材料

姚恺清, 宋崇虎, 方红, 王峰, 陈炼, 蒋少华, 查国君, 侯豪情

期刊论文

Experimental investigation on freeze−thaw durability of polymer concrete

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

Stress-strain relationship of concrete in freeze-thaw environment

ZOU Chaoying, ZHAO Juan, LIANG Feng

期刊论文

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

期刊论文

Soybean drying characteristics in microwave rotary dryer with forced convection

Ruifang WANG, Zhanyong LI, Yanhua LI, Jingsheng YE

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

A solar assisted heat pump drying system for grain in-store drying

Haifeng LI, Yanjun DAI, Jianguo DAI, Xibo WANG, Lei WEI,

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

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

Effects of previous drying of sediment on root functional traits and rhizoperformance of emerged macrophytes

期刊论文