An investigation on the bearing capacity of steel girder-concrete abutment joints

Chen Liang,Yuqing Liu,Changjun Zhao,Bo Lei,Jieliang Wu 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.38 No.3

To achieve a rational detail of the girder-abutment joints in composite integral bridges, and validate the performance of the joints with perfobond connectors, this paper proposes two innovative types of I-shaped steel girder-concrete abutment joints with perfobond connectors intended for the most of bearing capacity and the convenience of concrete pouring. The major difference between the two joints is the presence of the top flange inside the abutments. Two scaled models were investigated with tests and finite element method, and the damage mechanism was revealed. Results show that the joints meet design requirements no matter the top flange exists or not. Compared to the joint without top flange, the initial stiffness of the one with top flange is higher by 7%, and the strength is higher by 50%. The moment decreases linearly in both types of the joints. At design loads, perfobond connectors take about 70% and 50% of the external moment with and without top flange respectively, while at ultimate loads, perfobond connectors take 53% and 26% of the external moment respectively. The ultimate strengths of the reduced sections are suggested to be taken as the bending strengths of the joints.

F-box Protein Arabidillo-1 Promotes Lateral Root Development by Depressing the Functioning of GA3 in Arabidopsis

Changjun Mu,Ni Chen,Xiaofeng Li,Pengfei Jia,Zhaoyan Wang,Heng Liu 한국식물학회 2010 Journal of Plant Biology Vol.54 No.5

In Arabidopsis, Arabidillo-1 and Arabidillo-2have great sequence homology to Dictyostelium and metazoan β–catenin/Armadillo, which are important to animal and Dictyostelium development. Arabidillo-1 and Arabidillo-2 promote lateral root formation redundantly in Arabidopsis. Here, we showed that gibberellins (GA3) has a greater inhibitory effect on lateral root growth from the null mutant arabidillo-1 than from the wild type, suggesting that the mechanism for Arabidillo-1-regulated modulation of lateral root proliferation is associated with GA3-metabolic or signaling pathways. Our yeast two-hybrid analysis demonstrated that Arabidillo-1 interacts with ASK2 and ASK11, and that ASK2 can bind with the F-box domain of Arabidillo-1. Therefore, Arabidillo-1 is involved in the ubiquitin/26S proteasome-mediated proteolytic pathway. Based on these results, we conclude that Arabidillo-1 can degrade some positive regulator of the GA3 signaling pathway through selective protein degradation of ubiquitin/26S. Moreover, that process is believed to be the mechanism for Arabidillo-1 promotion of lateral root development in Arabidopsis.

Mild purification of multiwalled carbon nanotubes with increased selectivity for carbon impurity and residual metal removal

Chen Erdong,Liu Qiang,Wu Pan,He Jian,Liu Changjun,Jiang Wei 한국탄소학회 2024 Carbon Letters Vol.34 No.1

In this study, the refinement of Multiwalled Carbon Nanotubes (MWCNTs) derived from chemical vapor decomposition is investigated. An ultrasonic pretreatment method is employed to disentangle carbon and metal impurities intertwined with MWCNTs. The pretreated MWCNTs exhibit a marginal decrease in C–O/C = O content from 8.9 to 8.8%, accompanied by a 2.5% increase in sp3 carbon content, indicating a mildly destructive pretreatment approach. Subsequently, selective oxidation by CO2 and hydrochloric acid etching are utilized to selectively remove carbon impurities and residual metal, respectively. The resulting yield of intact MWCNTs is approximately 85.65 wt.%, signifying a 19.91% enhancement in the one-way yield of pristine MWCNTs. Notably, the residual metal content experiences a substantial reduction from 9.95 ± 2.42 wt.% to 1.34 ± 0.06 wt.%, representing a 15.68% increase in the removal rate. These compelling findings highlight the potential of employing a mild purification process for MWCNTs production, demonstrating promising application prospects.

The experimental investigation of bisphenol A degradation by Fenton process with different types of cyclodextrins

Wenjing Chen,Changjun Zou,Yuan Liu,Xiaoke Li 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.56 No.-

In this work, the degradation efficiencies of bisphenol A (BPA) by Fenton reaction were comparedsystematically with varying cyclodextrins. The results showed that the removal rate of BPA displays aconsiderable increase by Fenton reaction in presence of b-cyclodextrin (b-CD) and its derivatives. Specifically, 98 2% and 89 2% of BPA was removed with carboxymethyl-b-cyclodextrin (CMCD) andb-CD, respectively. Additionally, to understand the reaction mechanism, the structure activity ofcyclodextrins with substrate and the kinetic of Fenton reaction with cyclodextrins have beeninvestigated. Results showed that the structure activity was the major role for cyclodextrins in thissystem.

A Novel Electrochemical Biosensor Based on Graphene and Cu Nanowires Hybrid Nanocomposites

Mei Chen,CHANGJUN HOU,DANQUN HUO,Liang Dong,Mei Yang,Huanbao Fa 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.11

In this research, a new electrochemical sensor based on hybrid nanocomposite consisting of copper nanowires (CuNWs) and graphene (GR) were developed for the detection of organophosphorus pesticides (OPs). The surface morphology of the hybrid nanocomposite were studied by scanning electron microscope (SEM). The electrochemical behavior of the hybrid nanocomposites based sensor and its application for pesticides determination were evaluated by cyclic voltammetry (CV) and square wave voltammetry (SWV). Under optimized operational conditions, SWV was further employed for methyl parathion detection, which shows a wide dynamic range from 0.2 µM to 5 µM, a high sensitivity (69.2 · cm2 · µM-1) and the detection limit as low as 50 nM. It also had specific detection to the methyl parathion residues and had good reproducibility and stability. These results implicated the potential applicability of CuNWs/GNs-Chit hybrid nanocomposites in sensitive and selective detection of organophosphorus pesticides.

Effect of Heat Treatment on the Properties of a High Alloying Maraging Steel Fabricated by Laser Metal Deposition

Linjun Jiang,Changjun Chen,Min Zhang 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.1

Traditional maraging steels are not able to satisfy the development of modern industry. Optimizing the properties of maragingsteels is now a fascinating field. In this paper, a novel high alloying element maraging steel (HA-MS1) is successfullyprepared by laser metal deposition (LMD). Then differential scanning calorimetry (DSC) phase transformation analysis onthe as-deposited (AF) specimens was conducted and the reasonable aging heat treatment (AT) and solution + aging heattreatment (ST + AT) were subsequently proposed. These specimens were characterized by scanning electron microscopy(SEM), electron back-scattered diffraction (EBSD), X-ray diffraction (XRD), hardness test, wear test and potentiodynamicpolarization test for microstructure, phase, hardness, tribological and corrosive properties. The grain refinement and a largenumber of Ni3(Ti, Mo) intermetallic compounds in the matrix after AT resulted in superior hardness and wear resistance,while leading to poor corrosion resistance. Thereinto, specimens subjected to 460 °C AT possessed the ideal hardness andwear resistance of 638 HV and 1.75 × 10−6 mm3/Nm, respectively, with an increase of 68% and 118% compared to theas-deposited specimens. The austenite ( ) content of the ST + AT specimens increased drastically, reaching 23.1% for the820 °C ST + 460 °C AT specimens. This phenomenon resulted in a decreasing compatibility of mechanical properties thanthe AT specimens, but the specimens aged at 490 °C after solution treatment at 820 °C had the best corrosion resistance,mainly due to their good surface and more densification.

Dynamic behavior of SRC columns with built-in cross-shaped steels subjected to lateral impact

Yanhua Liu,Lei Zeng,Changjun Liu,Jinxu Mo,Buqing Chen 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.76 No.4

This paper presents an investigation on the dynamic behavior of SRC columns with built-in cross-shaped steels under impact load. Seven 1/2 scaled SRC specimens were subjected to low-speed impact by a gravity drop hammer test system. Three main parameters, including the lateral impact height, the axial compression ratios and the stirrup spacing, were considered in the response analysis of the specimens. The failure mode, deformation, the absorbed energy of columns, as well as impact loads are discussed. The results are mainly characterized by bending-shear failure, meanwhile specimens can maintain an acceptable integrity. More than 33% of the input impact energy is dissipated, which demonstrates its excellent impact resistance. As the impact height increases, the flexural cracks and shear cracks observed on the surface of specimens were denser and wider. The recorded time-history of impact force and mid-span displacement confirmed the three stages of relative movement between the hammer and the column. Additionally, the displacements had a notable delay compared to the rapid changes observed in the measured impact load. The deflection of the mid-span did not exceed 5.90mm while the impact load reached peak value. The impact resistance of the specimen can be improved by proper design for stirrup ratios and increasing the axial load. However, the cracking and spalling of the concrete cover at the impact point was obvious with the increasing in stiffness.

Fluorescent chemical probes for accurate tumor diagnosis and targeting therapy

Gao, Min,Yu, Fabiao,Lv, Changjun,Choo, Jaebum,Chen, Lingxin Royal Society of Chemistry, etc 2017 Chemical Society reviews Vol.46 No.8

<P>Surgical resection of solid tumors is currently the gold standard and preferred therapeutic strategy for cancer. Chemotherapy drugs also make a significant contribution by inhibiting the rapid growth of tumor cells and these two approaches are often combined to enhance treatment efficacy. However, surgery and chemotherapy inevitably lead to severe side effects and high systemic toxicity, which in turn results in poor prognosis. Precision medicine has promoted the development of treatment modalities that are developed to specifically target and kill tumor cells. Advances in<I>in vivo</I>medical imaging for visualizing tumor lesions can aid diagnosis, facilitate surgical resection, investigate therapeutic efficacy, and improve prognosis. In particular, the modality of fluorescence imaging has high specificity and sensitivity and has been utilized for medical imaging. Therefore, there are great opportunities for chemists and physicians to conceive, synthesize, and exploit new chemical probes that can image tumors and release chemotherapy drugs<I>in vivo</I>. This review focuses on small molecular ligand-targeted fluorescent imaging probes and fluorescent theranostics, including their design strategies and applications in clinical tumor treatment. The progress in chemical probes described here suggests that fluorescence imaging is a vital and rapidly developing field for interventional surgical imaging, as well as tumor diagnosis and therapy.</P>