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Preparation and characterization of

Chunhua XU, Dandan CHENG, Baoyu GAO, Zhilei YIN, Qinyan YUE, Xian ZHAO

《环境科学与工程前沿（英文）》 2012年 第6卷 第4期   页码 455-462 doi: 10.1007/s11783-010-0275-1

摘要： Batch adsorption experiments were conducted to explore the adsorption of Cr(VI) in aqueous solutions by -FeOOH-coated sand. We investigated the key factors which affected the adsorption process such as adsorbent dosage, initial pH, initial Cr(VI) ion concentration, contact time and temperature. The uptake of Cr(VI) was very rapid and 44.3%, 51.6%, 58.9% of the adsorption happened during the first 180 minutes at 293K, 303K and 313K, respectively. The pseudo-second-order rate equation successfully described the adsorption kinetics. To study the adsorption isotherm, two equilibrium models, the Langmuir and Freundlich isotherms, were adopted. At 293K, 303K and 313K, the adsorption capacities obtained from the Langmuir isotherm were 0.060, 0.070 and 0.076 mg Cr(VI) per gram of the adsorbent, respectively. Thermodynamic parameters such as the change of energy, enthalpy and entropy were calculated using the equilibrium constants. The negative value of and the positive value of showed that the adsorption of Cr(VI) in aqueous solutions by -FeOOH-coated sand was spontaneous, endothermic and occurred by physisorption.

关键词： β-FeOOH-coated sand     Cr(VI)     adsorption     isotherm     kinetics    

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Numerical simulation of compaction parameters for sand-filled embankment using large thickness sand filling

Wentao WANG, Chongzhi TU, Rong LUO

《结构与土木工程前沿（英文）》 2018年 第12卷 第4期   页码 568-576 doi: 10.1007/s11709-017-0444-4

摘要： The study uses the finite element method to simulate a new technique of highway sand embankment filling in Jianghan Plain district, which can raise the thickness of sand-filled layer from 30 cm to 70 cm and can significantly shorten the construction period based on the guarantee of sand embankment construction quality. After simulating the three compacting proposals carried out on the field test, the study uses COMSOL software to research on the compacting effects of sand-filled layers in larger thicknesses by 22 ton vibratory roller alone, and then to investigate the steady compacting effect of 12 ton vibratory roller. The simulation results indicate that the sand-filled layer thickness of 70 cm is suitable for the new sand filling technique, and the sand-filled embankment project with tight construction period is suggested to choose the 12 ton vibration roller for steady compaction.

关键词： sand embankment     compaction in large thickness     numerical simulation     small size vibratory roller     steady compaction    

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Unified description of sand behavior

Feng ZHANG, Bin YE, Guanlin YE

《结构与土木工程前沿（英文）》 2011年 第5卷 第2期   页码 121-150 doi: 10.1007/s11709-011-0104-z

摘要： In this paper, the mechanical behavior of sand, was systematically described and modeled with a elastoplastic model proposed by Zhang et al. [ ]. Without losing the generality of the sand, a specific sand called as Toyoura sand, a typical clean sand found in Japan, has been discussed in detail. In the model, the results of conventional triaxial tests of the sand under different loading and drainage conditions were simulated with a fixed set of material parameters. The model only employs eight parameters among which five parameters are the same as those used in Cam-clay model. Once the parameters are determined with the conventional drained triaxial compression tests and undrained triaxial cyclic loading tests, then they are fixed to uniquely describe the overall mechanical behaviors of the Toyoura sand, without changing the values of the eight parameters irrespective of what kind of the loadings or the drainage conditions may be. The capability of the model is discussed in a theoretical way.

关键词： constitutive model     sand     stress-induced anisotropy     density     structure    

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Carbon-coated lithium titanate: effect of carbon precursor addition processes on the electrochemical

Shilei Ding, Zelong Jiang, Jing Gu, Hongliang Zhang, Jiajia Cai, Dongdong Wang

《化学科学与工程前沿（英文）》 2021年 第15卷 第1期   页码 148-155 doi: 10.1007/s11705-020-2022-x

摘要： In this paper, two carbon-coated lithium titanate (LTO-C1 and LTO-C2) composites were synthesized using the ball-milling-assisted calcination method with different carbon precursor addition processes. The physical and electrochemical properties of the as-synthesized negative electrode materials were characterized to investigate the effects of two carbon-coated LTO synthesis processes on the electrochemical performance of LTO. The results show that the LTO-C2 synthesized by using Li CO and TiO as the raw materials and sucrose as the carbon source in a one-pot method has less polarization during lithium insertion and extraction, minimal charge transfer impedance value and the best electrochemical performance among all samples. At the current density of 300 mA·h·g , the LTO-C2 composite delivers a charge capacity of 126.9 mA·h·g , and the reversible capacity after 300 cycles exceeds 121.3 mA·h·g in the voltage range of 1.0–3.0 V. Furthermore, the electrochemical impedance spectra show that LTO-C2 has higher electronic conductivity and lithium diffusion coefficient, which indicates the advantages in electrode kinetics over LTO and LTO-C1. The results clarify the best electrochemical properties of the carbon-coated LTO-C2 composite prepared by the one-pot method.

关键词： lithium titanate     carbon-coated     carbon precursor     synthetic process    

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Research review of the cement sand and gravel (CSG) dam

Xin CAI, Yingli WU, Xingwen GUO, Yu MING

《结构与土木工程前沿（英文）》 2012年 第6卷 第1期   页码 19-24 doi: 10.1007/s11709-012-0145-y

摘要： The cement sand and gravel (CSG) dam is a new style of dam that owes the advantages both of the concrete faced rock-fill dam (CRFD) and roller compacted concrete (RCC) gravity dam, because of which it has attracted much attention of experts home and abroad. At present, some researches on physic-mechanical property of CSG material and work behavior of CSG dam have been done. This paper introduces the development and characteristics of CSG dam systematically, and summarizes the progress of the study on basic tests, constitutive relation of CSG material and numerical analysis of CSG dam, in addition, indicates research and application aspect of the dam.

关键词： cement sand and gravel (CSG) dam     cement sand and gravel (CSG) material     research review    

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Effects of microfine aggregate in manufactured sand on bleeding and plastic shrinkage cracking of concrete

Branavan ARULMOLY; Chaminda KONTHESINGHA; Anura NANAYAKKARA

《结构与土木工程前沿（英文）》 2022年 第16卷 第11期   页码 1453-1473 doi: 10.1007/s11709-022-0877-2

摘要： Construction industries have started to utilize manufactured sand (MS) as an effective alternative for river sand in concrete. High-grade parent rocks are crushed to obtain MS, which also produces a considerable amount of microfine aggregate (MFA). The higher percentage of MFA could lead to both positive and negative effects on the performance of cement-based mixes. This research was done to examine the influence of varying MFA levels, specifically 0%, 3%, 6%, 9%, and 12% (by weight) as the partial replacements of MS on bleeding and plastic shrinkage cracking of concrete. In addition to the varying MFA levels, some concrete mixes also included fly ash (FA) and superplasticizer to investigate the effect of free-water content in the mixes. The bleeding test data were taken as on-site measurements, while the cracks from the plastic shrinkage cracking test were evaluated using an image processing technique. The results concluded that the MFA replacements and the effective water-to-cement ratio have a significant effect on the selected concrete properties. With the increasing replacement levels, cumulative bleeding and crack initiation life gradually decreased, while a progressive increase was observed for crack width, crack length, and crack area.

关键词： manufactured sand     fresh concrete     microfines     admixtures     shrinkage     cracking    

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Impacts of backwashing on micropollutant removal and associated microbial assembly processes in sand

《环境科学与工程前沿（英文）》 2023年 第17卷 第3期 doi: 10.1007/s11783-023-1634-z

摘要：

● Backwashing in sand filters with 2-h and 4-h EBCTs was simulated.

关键词： Sand filter     Backwashing     Recovery     Micropollutants     Community composition    

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Destructive and non-destructive evaluation of concrete for optimum sand to aggregate volume ratio

《结构与土木工程前沿（英文）》 2021年 第15卷 第6期   页码 1400-1414 doi: 10.1007/s11709-021-0779-8

摘要： Aggregates are the biggest contributor to concrete volume and are a crucial parameter in dictating its mechanical properties. As such, a detailed experimental investigation was carried out to evaluate the effect of sand-to-aggregate volume ratio (s/a) on the mechanical properties of concrete utilizing both destructive and non-destructive testing (employing UPV (ultrasonic pulse velocity) measurements). For investigation, standard cylindrical concrete samples were made with different s/a (0.36, 0.40, 0.44, 0.48, 0.52, and 0.56), cement content (340 and 450 kg/m3), water-to-cement ratio (0.45 and 0.50), and maximum aggregate size (12 and 19 mm). The effect of these design parameters on the 7, 14, and 28 d compressive strength, tensile strength, elastic modulus, and UPV of concrete were assessed. The careful analysis demonstrates that aggregate proportions and size need to be optimized for formulating mix designs; optimum ratios of s/a were found to be 0.40 and 0.44 for the maximum aggregate size of 12 and 19 mm, respectively, irrespective of the W/C (water-to-cement) and cement content.

关键词： aggregates     non-destructive testing     sand-to-aggregate volume ratio (s/a)     maximum aggregate size (MAS)    

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Carbon-coated Ni-Co alloy catalysts: preparation and performance for aqueous phase hydrodeoxygenation

《化学科学与工程前沿（英文）》 2022年 第16卷 第3期   页码 443-460 doi: 10.1007/s11705-021-2079-1

摘要： Carbon-coated Ni, Co and Ni-Co alloy catalysts were prepared by the carbonization of the metal doped resorcinol-formaldehyde resins synthesized by the one-pot extended Stöber method. It was found that the introduction of Co remarkably reduced the carbon microsphere size. The metallic Ni, Co, and Ni-Co alloy particles (mainly 10–12 nm) were uniformly distributed in carbon microspheres. A charge transfer from Ni to Co appeared in the Ni-Co alloy. Compared with those of metallic Ni and Co, the d-band center of the Ni-Co alloy shifted away from and toward the Fermi level, respectively. In the in-situ aqueous phase hydrodeoxygenation of methyl palmitate with methanol as the hydrogen donor at 330 °C, the decarbonylation/decarboxylation pathway dominated on all catalysts. The Ni-Co@C catalysts gave higher activity than the Ni@C and Co@C catalysts, and the yields of n-pentadecane and n-C6–n-C16 reached 71.6% and 92.6%, respectively. The excellent performance of Ni-Co@C is attributed to the electronic interactions between Ni and Co and the small carbon microspheres. Due to the confinement effect of carbon, the metal particles showed high resistance to sintering under harsh hydrothermal conditions. Catalyst deactivation is due to the carbonaceous deposition, and the regeneration with CO2 recovered the catalyst reactivity.

关键词： Stöber method     carbon-coated Ni-Co alloy     in-situ hydrodeoxygenation     methyl palmitate     decarbonylation/decarboxylation    

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Spray-coated SnO

Yaqin Wang, Lin Yang, Chunxiang Dall’Agnese, Gang Chen, Ai-Jun Li, Xiao-Feng Wang

《化学科学与工程前沿（英文）》 2021年 第15卷 第1期   页码 180-186 doi: 10.1007/s11705-020-1917-x

摘要： SnO has been proven to be an effective electron transport layer (ETL) material for perovskite solar cells (PSCs) owing to its excellent electrical and optical properties. Here, we introduce a viable spray coating method for the preparation of SnO films. Then, we employ a SnO film prepared using the spray coating method as an ETL for PSCs. The PSC based on the spray-coated SnO ETL achieves a power conversion efficiency of 17.78%, which is comparable to that of PSCs based on conventional spin-coated SnO films. The large-area SnO films prepared by spray coating exhibit good repeatability for device performance. This study shows that SnO films prepared by spray coating can be applied as ETLs for stable and high-efficiency PSCs. Because the proposed method involves low material consumption, it enables the low-cost and large-scale production of PSCs.

关键词： spray coating     SnO2 film     ETL     PSCs    

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Drug-coated balloon-only strategy for percutaneous coronary intervention of left main coronary artery

《医学前沿（英文）》 2023年 第17卷 第1期   页码 75-84 doi: 10.1007/s11684-022-0950-1

摘要： This retrospective single-center registry study included all consecutive patients who underwent percutaneous coronary intervention (PCI) for a de novo left main coronary artery lesion using drug coated-balloon (DCB)-only strategy between August 2011 and December 2018. To best of our knowledge, no previous studies of DCB-only strategy of treating de novo left main coronary artery disease, exist. The primary endpoint was major adverse cardiovascular events (MACEs) including cardiac death, non-fatal myocardial infarction, and target lesion revascularization (TLR). The cohort was divided into two groups depending on weather the lesion preparation was done according to the international consensus group guidelines. Sixty-six patients (mean age 75±8.6, 72% male), 52% of whom had acute coronary syndrome, underwent left main PCI with the DCB-only strategy. No procedural mortality and no acute closures of the treated left main occurred. At 12 months, MACE and TLR occurred in 24% and 6% of the whole cohort, respectively. If the lesion preparation was done according to the guidelines, the MACE and TLR rates were 21.2% and 1.9%. Left main PCI with the DCB only-strategy is safe leading to acceptable MACE and low TLR rates at one year, if the lesion preparation is done according to the guidelines.

关键词： drug-coated balloon     left main     high bleeding risk     predilatation     calcifield lesion     percutaneous coronary intervention    

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Effects of coarse and fine aggregates on long-term mechanical properties of sea sand recycled aggregate

《结构与土木工程前沿（英文）》 2021年 第15卷 第3期   页码 754-772 doi: 10.1007/s11709-021-0711-2

摘要： Typical effects of coarse and fine aggregates on the long-term properties of sea sand recycled aggregate concrete (SSRAC) are analyzed by a series of axial compression tests. Two different types of fine (coarse) aggregates are considered: sea sand and river sand (natural and recycled coarse aggregates). Variations in SSRAC properties at different ages are investigated. A novel test system is developed via axial compression experiments and the digital image correlation method to obtain the deformation field and crack development of concrete. Supportive results show that the compressive strength of SSRAC increase with decreasing recycled coarse aggregate replacement percentage and increasing sea sand chloride ion content. The elastic modulus of SSRAC increases with age. However, the Poisson’s ratio reduces after 2 years. Typical axial stress–strain curves of SSRAC vary with age. Generally, the effect of coarse aggregates on the axial deformation of SSRAC is clear; however, the deformation differences between coarse aggregate and cement mortar reduce by adopting sea sand. The aggregate type changes the crack characteristics and propagation of SSRAC. Finally, an analytical expression is suggested to construct the long-term stress–strain curve of SSRAC.

关键词： sea sand recycled aggregate concrete     recycled coarse aggregate replacement percentage     sea sand chloride ion content     long-term mechanical properties     stress–strain curve    

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Performance of fiber reinforced clayey sand composite

Amin CHEGENIZADEH, Hamid NIKRAZ

《结构与土木工程前沿（英文）》 2012年 第6卷 第2期   页码 147-152 doi: 10.1007/s11709-012-0158-6

摘要： Soils and their related behavior have always been the subject of many studies. Recent researches show some interests in investigation of inclusion of randomly distributed fiber in soil. This study focuses on effect of fiber inclusion on the strength and other parameters of clayey sand composite material. First part of this study is related to effective parameters on strength of the clayey sand composite with using natural fiber and plastic fiber and different fiber contents and length. Triaxial consolidated undrained (CU) tests were carried out to investigate behavior of the composite under different condition. The fiber percentage varied from 0% (for unreinforced samples) to 4% and fiber length varied from 8 to 25 mm. The fiber length and fiber content found to play important rule on the strength of fiber reinforced composite.

关键词： triaxial     consolidated undrained (CU)     fiber     strength    

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The coupling of sand with ZVI/oxidants achieved proportional and highly efficient removal of arsenic

Sana Ullah, Xuejun Guo, Xiaoyan Luo, Xiangyuan Zhang, Yameng Li, Ziyu Liang

《环境科学与工程前沿（英文）》 2020年 第14卷 第6期 doi: 10.1007/s11783-020-1273-6

摘要： Abstract • Simply doping sands with ZVI achieved an even activation of ZVI by oxidants. • Sand doping facilitated proportional As trapping along the ZVI/oxidants column. • ZVI/sand/oxidants are highly efficient for arsenic removal. • ZVI/sand/oxidants reduced significantly the Fe2+ leaching and effluent turbidity. • More than 54% of arsenic was reduced to As(III) in ZVI/sand/oxidants system. The coupling of zero-valent iron (ZVI) with common oxidants has recently achieved very rapid and highly efficient removal of Heavy metals from wastewater. However, the uniform activation of ZVI throughout the column and the proportional removal of target contaminants are urgently required for the prevention of premature filter clogging and the extension of the effective column operational time. In this study, we successfully achieved this objective by simply doping granular sand with ZVI at appropriate weight ratios. When pure ZVI packed column was spiked with oxidants, the majority of As trapping occurred between the column inlet and the first sampling point. In a packed column with a 1:20 mixture of ZVI and sand, the average As removal efficiency was 36 (1st), 13.1 (2nd), 18.5 (3rd), 19.2 (4th) and 5.9% (5th outlet). The overall arsenic removal performance of the composite filling system of ZVI/sand was equally as efficient as that of the previous pure ZVI-packed system. Moreover, the leaching of Fe was significantly reduced with an increased sand ratio, resulting in clearer water with less turbidity. The results of X-ray photoelectron spectroscopy (XPS) demonstrated that more than 54% of the arsenic was reduced to As(III). X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed the extensive corrosion of the ZVI surface, which resulted in various species of iron oxyhydroxides responsible for the highly efficient sequester of arsenic through reduction, adsorption, and coprecipitation.

关键词： Arsenic     ZVI     Sand     Oxidants     Fixed-bed Column     Removal    

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Effect of microlimestone on properties of self-consolidating concrete with manufactured sand and mineral

Fulin Qu, Wengui Li, Xiaohui Zeng, Zhiyu Luo, Kejin Wang, Daichao Sheng

《结构与土木工程前沿（英文）》 2020年 第14卷 第6期   页码 1545-1560 doi: 10.1007/s11709-020-0678-4

摘要： Self-consolidating concrete (SCC) with manufactured sand (MSCC) is crucial to guarantee the quality of concrete construction technology and the associated property. The properties of MSCC with different microlimestone powder (MLS) replacements of retreated manufactured sand (TMsand) are investigated in this study. The result indicates that high-performance SCC, made using TMsand (TMSCC), achieved high workability, good mechanical properties, and durability by optimizing MLS content and adding fly ash and silica fume. In particular, the TMSCC with 12% MLS content exhibits the best workability, and the TMSCC with 4% MLS content has the highest strength in the late age, which is even better than that of SCC made with the river sand (Rsand). Though MLS content slightly affects the hydration reaction of cement and mainly plays a role in the nucleation process in concrete structures compared to silica fume and fly ash, increasing MLS content can evidently have a significant impact on the early age hydration progress. TMsand with MLS content ranging from 8% to 12% may be a suitable alternative for the Rsand used in the SCC as fine aggregate. The obtained results can be used to promote the application of SCC made with manufactured sand and mineral admixtures for concrete-based infrastructure.

关键词： microlimestone powder     manufactured sand     retreated manufactured sand     self-consolidating concrete     mineral admixture    

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标题 作者 时间 类型 操作

Preparation and characterization of

Chunhua XU, Dandan CHENG, Baoyu GAO, Zhilei YIN, Qinyan YUE, Xian ZHAO

期刊论文

Numerical simulation of compaction parameters for sand-filled embankment using large thickness sand filling

Wentao WANG, Chongzhi TU, Rong LUO

期刊论文

Unified description of sand behavior

Feng ZHANG, Bin YE, Guanlin YE

期刊论文

Carbon-coated lithium titanate: effect of carbon precursor addition processes on the electrochemical

Shilei Ding, Zelong Jiang, Jing Gu, Hongliang Zhang, Jiajia Cai, Dongdong Wang

期刊论文

Research review of the cement sand and gravel (CSG) dam

Xin CAI, Yingli WU, Xingwen GUO, Yu MING

期刊论文

Effects of microfine aggregate in manufactured sand on bleeding and plastic shrinkage cracking of concrete

Branavan ARULMOLY; Chaminda KONTHESINGHA; Anura NANAYAKKARA

期刊论文

Impacts of backwashing on micropollutant removal and associated microbial assembly processes in sand

期刊论文

Destructive and non-destructive evaluation of concrete for optimum sand to aggregate volume ratio

期刊论文

Carbon-coated Ni-Co alloy catalysts: preparation and performance for aqueous phase hydrodeoxygenation

期刊论文

Spray-coated SnO

Yaqin Wang, Lin Yang, Chunxiang Dall’Agnese, Gang Chen, Ai-Jun Li, Xiao-Feng Wang

期刊论文

Drug-coated balloon-only strategy for percutaneous coronary intervention of left main coronary artery

期刊论文

Effects of coarse and fine aggregates on long-term mechanical properties of sea sand recycled aggregate

期刊论文

Performance of fiber reinforced clayey sand composite

Amin CHEGENIZADEH, Hamid NIKRAZ

期刊论文

The coupling of sand with ZVI/oxidants achieved proportional and highly efficient removal of arsenic

Sana Ullah, Xuejun Guo, Xiaoyan Luo, Xiangyuan Zhang, Yameng Li, Ziyu Liang

期刊论文

Effect of microlimestone on properties of self-consolidating concrete with manufactured sand and mineral

Fulin Qu, Wengui Li, Xiaohui Zeng, Zhiyu Luo, Kejin Wang, Daichao Sheng

期刊论文