Analysis on the influence of type and proportion of aggregates on the performance of PU based polymer concrete

Zhuoyuan Chen,Jianbo Zhao,Peiyang Li,Aizhong Qin,Zhihua Gao,Wenfen Zhao,Shaocan Wang,Guanfeng Lia 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.1

In this work, the fabrication and improvement of a lightweight and corrosion-resistant polyurethane (PU) based polymerconcrete are studied. The aggregate in traditional polymer concrete is generally crushed stone. Due to the low bonding strengthbetween polymer matrix and crushed stone, it is easy to fall off between polymer matrix and crushed stone after long-termuse, resulting in the degradation of the performance of polymer concrete. In order to overcome the low bond strength betweencrushed stone and polymer matrix in polymer concrete, modified polyetheramine particles were used to enhance the finalmechanical parameters of PU based polymer concrete. A series of mechanical and environmental tests were carried out, andthe effects of aggregates addition ratio and type on the mechanical properties of polymer concrete were analyzed. Theexperimental results determined the influence mechanism of aggregates proportion and type on the mechanical properties ofpolymer concrete, and obtained the appropriate aggregates type and addition proportion. The current work reveals that usingmodified polyetheramine particles as aggregates of polymer concrete can significantly enhance the bond strength anddurability between polymer matrix and aggregates. The density of this polymer concrete proposed in this paper is about 1.2g/mm3; The density of traditional polymer concrete is about 1.5-1.8 g/mm3, the weight can be reduced by 25%, and there isno problem of falling off between polymer matrix and aggregate.

Dynamic assessment of the seismic isolation infl uence for various aircraft impact loads on the CPR1000 containment

Runyu Mei,Jianbo Li,Gao Lin,Xiuyun Zhu 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.8

An aircraft impact (AI) on a nuclear power plant (NPP) is considered to be a beyond-design-basis eventthat draws considerable attention in the nuclear field. As some NPPs have already adopted the seismicisolation technology, and there are relevant standards to guide the application of this technology infuture NPPs, a new challenge is that nuclear power engineers have to determine a reasonable method forperforming AI analysis of base-isolated NPPs. Hence, dynamic influences of the seismic isolation on thevibration and structural damage characteristics of the base-isolated CPR1000 containment are studiedunder various aircraft loads. Unlike the seismic case, the impact energy of AI is directly impacting on thesuperstructure. Under the coupled influence of the seismic isolation and the various AI load, the flexibleisolation layer weakens the constraint function of the foundation on the superstructure, the results showthat the seismic isolation bearings will produce a large horizontal deformation if the AI load is largeenough, the acceleration response at the base-mat will also be significantly affected by the differenthorizontal stiffness of the isolation bearing. These concerns require consideration during the design ofthe seismic isolation system

Design and Analysis of Isolation Effectiveness for Three-dimensional Base-seismic Isolation of Nuclear Island Building

Xiuyun Zhu,Gao Lin,Rong Pan,Jianbo Li 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.1

In order to investigate the application of 3D base-seismic isolation system in nuclear power plants(NPPs), comprehensive analysis of constitution and design theory for 3-dimensional combined isolationbearing (3D-CIB) was presented and derived. Four different vertical stiffness of 3D-CIB was designed toisolate the nuclear island (NI) building. This paper aimed at investigating the isolation effectiveness of3D-CIB through modal analysis and dynamic time-history analysis. Numerical results in terms of dynamicresponse of 3D-CIB, relative displacement response, acceleration and floor response spectra (FRS)of the superstructure were compared to validate the reliability of 3D-CIB in mitigating seismic response. The results showed that 3D-CIB can significantly attenuate the horizontal acceleration response, and afair amount of the vertical acceleration response reduction of the upper structure was still observed. 3DCIBplays a significant role in reducing the horizontal and vertical FRS, the vertical FRS basically do notvary with the floor height. The smaller the vertical stiffness of 3D-CIB is, the better the vertical isolationeffectiveness is, whereas, it will increase the displacement and the rocking effect of superstructure. Although the advantage of 3D-CIB is that the vertical stiffness can be flexibly adjusted, it should bedesigned by properly accounting for the balance between the isolation effectiveness and displacementcontrol including rocking effect. The results of this study can provide the technical basis and guidance forthe application of 3D-CIB to engineering structure.

Rheological analysis of titanium dioxide nano-whisker based electrorheological fluids

Ke Zhang,Chun Yan Gao,Hyoung Jin Choi,Jianbo Yin,Xiaopeng Zhao 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.83 No.-

Understanding yield stress of electrorheological (ER)fluids becomes important for not only developmentof advanced ER materials but also their engineering applications. This study reanalyzed dynamic yieldstresses of both titanium dioxide nano-whisker- and titanium dioxide nano-particle-based ERsuspensions under an input electricalfield, based on the universal yield stress function proposed. The experimental data was plotted well to a single line by the scaled universal yield stress function via adeduced critical electricalfield value which divides electricfield dependent yield stress region with aslope of 1.5 from that with 2.0 of polarization mechanism.

Pressure-induced semiconductor-to-metal phase transition of a charge-ordered indium halide perovskite

Lin, Jia,Chen, Hong,Gao, Yang,Cai, Yao,Jin, Jianbo,Etman, Ahmed S.,Kang, Joohoon,Lei, Teng,Lin, Zhenni,Folgueras, Maria C.,Quan, Li Na,Kong, Qiao,Sherburne, Matthew,Asta, Mark,Sun, Junliang,Toney, Mic National Academy of Sciences 2019 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.116 No.47

<P><B>Significance</B></P><P>Metal halide perovskites attract great interest for a wide range of applications due to their remarkable optoelectronic properties. The development of environmentally friendly halide perovskite materials with various crystal structures and compositions offers unprecedented opportunities to achieve desired properties and applications. In this work, we demonstrated an In-based, charge-ordered all-inorganic halide double perovskite with the composition of Cs<SUB>2</SUB>In(I)In(III)Cl<SUB>6</SUB> synthesized by solid-state reaction. High-pressure optical properties were studied, and a pressure-driven, fully reversible semiconductor–metal phase transition was discovered. This In-based charge-ordered structure may inspire new understanding of halide perovskite as well as provide a platform for future discovery of exotic electronic phenomena such as high-<I>T</I><SUB>C</SUB> superconductivity in halide perovskite compounds.</P><P>Phase transitions in halide perovskites triggered by external stimuli generate significantly different material properties, providing a great opportunity for broad applications. Here, we demonstrate an In-based, charge-ordered (In<SUP>+</SUP>/In<SUP>3+</SUP>) inorganic halide perovskite with the composition of Cs<SUB>2</SUB>In(I)In(III)Cl<SUB>6</SUB> in which a pressure-driven semiconductor-to-metal phase transition exists. The single crystals, synthesized via a solid-state reaction method, crystallize in a distorted perovskite structure with space group <I>I</I>4/<I>m</I> with <I>a</I> = 17.2604(12) Å, <I>c</I> = 11.0113(16) Å if both the strong reflections and superstructures are considered. The supercell was further confirmed by rotation electron diffraction measurement. The pressure-induced semiconductor-to-metal phase transition was demonstrated by high-pressure Raman and absorbance spectroscopies and was consistent with theoretical modeling. This type of charge-ordered inorganic halide perovskite with a pressure-induced semiconductor-to-metal phase transition may inspire a range of potential applications.</P>

An improved time-domain approach for the spectra-compatible seismic motion generation considering intrinsic non-stationary features

Cheng Feng,Li Jianbo,Ding Zhixin,Lin Gao 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.3

The dynamic structural responses are sensitive to the time-frequency content of seismic waves, and seismic input motions in time-history analysis are usually required to be compatible with design response spectra according to nuclear codes. In order to generate spectra-compatible input motions while maintaining the intrinsic non-stationarity of seismic waves, an improved time-domain approach is proposed in this paper. To maintain the nonstationary characteristics of the given seismic waves, a new time-frequency envelope function is constructed using the Hilbert amplitude spectrum. Based on the intrinsic mode functions (IMFs) obtained from given seismic waves through variational mode decomposition, a new corrective time history is constructed to locally modify the given seismic waves. The proposed corrective time history and time-frequency envelope function are unique for each earthquake records as they are extracted from the given seismic waves. In addition, a dimension reduction iterative technique is presented herein to simultaneously superimpose corrective time histories of all the damping ratios at a specific frequency in the time domain according to optimal weights, which are found by the genetic algorithm (GA). Examples are presented to show the capability of the proposed approach in generating spectra-compatible time histories, especially in maintaining the nonstationary characteristics of seismic records. And numerical results reveal that the modified time histories generated by the proposed method can obtain similar dynamic behaviors of AP1000 nuclear power plant with the natural seismic records. Thus, the proposed method can be efficiently used in the design practices

Spectral CT: Preliminary Studies in the Liver Cirrhosis

Peijie Lv,XiaoZhu Lin,Jianbo Gao,Kemin Chen 대한영상의학회 2012 Korean Journal of Radiology Vol.13 No.4

Objective: To investigate the value of spectral CT imaging in the diagnosis and classification of liver cirrhosis during the arterial phase (AP) and portal venous phase (PVP). Materials and Methods: Thirty-eight patients with liver cirrhosis (Child-Pugh class A/B/C: n = 10/14/14), and 43 patients with healthy livers, participated in this study. The researchers used abdominal spectral CT imaging during AP and PVP. Iodine concentration, derived from the iodine-based material-decomposition image and the iodine concentration ratio (ICratio) between AP and PVP, were obtained. Statistical analyses {two-sample t test, One-factor analysis of variance, and area under the receiver operating characteristic curve (A [z])} were performed. Results: The mean normalized iodine concentration (NIC) (0.5 ± 0.12) during PVP in the control group was significantly higher than that in the study group (0.4 ± 0.10 on average, 0.4 ± 0.08 for Class A, 0.4 ± 0.15 for Class B, and 0.4 ± 0.06 for Class C) (All p < 0.05). Within the cirrhotic liver group, the mean NIC for Class C during the AP (0.1 ± 0.05) was significantly higher than NICs for Classes A (0.1 ± 0.06) and B (0.1 ± 0.03) (Both p < 0.05). The ICratio in the study group (0.4 ± 0.15), especially for Class C (0.5 ± 0.14), was higher than that in the control group (0.3 ± 0.15) (p < 0.05).The combination of NIC and ICratio showed high sensitivity and specificity for differentiating healthy liver from cirrhotic liver, especially in Class C cirrhotic liver. Conclusion: Spectral CT Provides a quantitative method with which to analyze the cirrhotic liver, and shows the potential value in the classification of liver cirrhosis. Objective: To investigate the value of spectral CT imaging in the diagnosis and classification of liver cirrhosis during the arterial phase (AP) and portal venous phase (PVP). Materials and Methods: Thirty-eight patients with liver cirrhosis (Child-Pugh class A/B/C: n = 10/14/14), and 43 patients with healthy livers, participated in this study. The researchers used abdominal spectral CT imaging during AP and PVP. Iodine concentration, derived from the iodine-based material-decomposition image and the iodine concentration ratio (ICratio) between AP and PVP, were obtained. Statistical analyses {two-sample t test, One-factor analysis of variance, and area under the receiver operating characteristic curve (A [z])} were performed. Results: The mean normalized iodine concentration (NIC) (0.5 ± 0.12) during PVP in the control group was significantly higher than that in the study group (0.4 ± 0.10 on average, 0.4 ± 0.08 for Class A, 0.4 ± 0.15 for Class B, and 0.4 ± 0.06 for Class C) (All p < 0.05). Within the cirrhotic liver group, the mean NIC for Class C during the AP (0.1 ± 0.05) was significantly higher than NICs for Classes A (0.1 ± 0.06) and B (0.1 ± 0.03) (Both p < 0.05). The ICratio in the study group (0.4 ± 0.15), especially for Class C (0.5 ± 0.14), was higher than that in the control group (0.3 ± 0.15) (p < 0.05).The combination of NIC and ICratio showed high sensitivity and specificity for differentiating healthy liver from cirrhotic liver, especially in Class C cirrhotic liver. Conclusion: Spectral CT Provides a quantitative method with which to analyze the cirrhotic liver, and shows the potential value in the classification of liver cirrhosis.

Roles of RpoS in Yersinia pseudotuberculosis stress survival, motility, biofilm formation and type VI secretion system expression

Jingyuan Guan,Xiao Xiao,Shengjuan Xu,Fen Gao,Jianbo Wang,Tietao Wang,Yunhong Song,Junfeng Pan,Xihui Shen,Yao Wang 한국미생물학회 2015 The journal of microbiology Vol.53 No.9

RpoS (σS), the stationary phase/stress σ factor, controls the expression of a large number of genes involved in cellular responses to a variety of stresses. However, the role of RpoS appears to differ in different bacteria. While RpoS is an important regulator of flagellum biosynthesis, it is associated with biofilm development in Edwardsiella tarda. Biofilms are dense communities formed by bacteria and are important for microbe survival under unfavorable conditions. The type VI secretion system (T6SS) discovered recently is reportedly associated with several phenotypes, ranging from biofilm formation to stress sensing. For example, Vibrio anguillarum T6SS was proposed to serve as a sensor for extracytoplasmic signals and modulates RpoS expression and stress response. In this study, we investigated the physiological roles of RpoS in Yersinia pseudotuberculosis, including bacterial survival under stress conditions, flagella formation, biofilm development and T6SS expression. We found that RpoS is important in resistance to multiple stressors–including H2O2, acid, osmotic and heat shock–in Y. pseudotuberculosis. In addition, our study showed that RpoS not only modulates the expression of T6SS but also regulates flagellum formation by positively controlling the flagellar master regulatory gene flhDC, and affects the formation of biofilm on Caenorhabditis elegans by regulating the synthesis of exopolysaccharides. Taken together, these results show that RpoS plays a central role in cell fitness under several adverse conditions in Y. pseudotuberculosis.

Combined Use of Automatic Tube Voltage Selection and Current Modulation with Iterative Reconstruction for CT Evaluation of Small Hypervascular Hepatocellular Carcinomas: Effect on Lesion Conspicuity and Image Quality

Peijie Lv,Jie Liu,Rui Zhang,Yan Jia,Jianbo Gao 대한영상의학회 2015 Korean Journal of Radiology Vol.16 No.3

To assess the lesion conspicuity and image quality in CT evaluation of small (≤ 3 cm) hepatocellular carcinomas (HCCs) using automatic tube voltage selection (ATVS) and automatic tube current modulation (ATCM) with or without iterative reconstruction. One hundred and five patients with 123 HCC lesions were included. Fifty-seven patients were scanned using both ATVS and ATCM and images were reconstructed using either filtered back-projection (FBP) (group A1) or sinogram-affirmed iterative reconstruction (SAFIRE) (group A2). Forty-eight patients were imaged using only ATCM, with a fixed tube potential of 120 kVp and FBP reconstruction (group B). Quantitative parameters (image noise in Hounsfield unit and contrast-to-noise ratio of the aorta, the liver, and the hepatic tumors) and qualitative visual parameters (image noise, overall image quality, and lesion conspicuity as graded on a 5-point scale) were compared among the groups. Group A2 scanned with the automatically chosen 80 kVp and 100 kVp tube voltages ranked the best in lesion conspicuity and subjective and objective image quality (p values ranging from < 0.001 to 0.004) among the three groups, except for overall image quality between group A2 and group B (p = 0.022). Group A1 showed higher image noise (p = 0.005) but similar lesion conspicuity and overall image quality as compared with group B. The radiation dose in group A was 19% lower than that in group B (p = 0.022). CT scanning with combined use of ATVS and ATCM and image reconstruction with SAFIRE algorithm provides higher lesion conspicuity and better image quality for evaluating small hepatic HCCs with radiation dose reduction.