Numerical Simulation of the Coalescence Behavior of Intermittent Structures with Fissures

Qianqian Dong,Yulin Wu,Qiyang Chen 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.4

To further study the failure behavior of the rock-like materials containing intermittent fissures subjected to uniaxial compression, 3D printing technology was adopted to manufacture specimens with prefabricated kinked and straight fissures (K-S fissure). The order of average peak strength was -45o > -90o > +90o > +45o. The influence of different parameters, including the effective length and inclination angle of branch fissure, on the coalescence pattern was discussed. Results showed that two failure modes were observed: Model I represented tensile-shear composite failure in the rock bridge area, while Model II showed non-coalescence occurring. The effective length parameter presented a relatively larger influence than the inclination angle on the failure behavior. Additionally, Model I was discovered to tend to occur in the rock bridge region when the branch fissure turned anticlockwise. Based on numerical simulation using the Realistic Failure Process Analysis (RFPA2D), a quick damage criterion approach was proposed to estimate the coalescence behavior in the rock bridge, which was beneficial to determine coalescence pattern and failure behavior. Based on the curve fitted by the simulation, the coalescence pattern of cracks initiated from pre-existing intermittent fissures occurs in the tensile-shear composite fracture pattern, while non-coalescence occurs in the rock bridge below the curve.

Experimental Study on Cracking Behaviour of Intermittent Double S-shaped Fissures under Uniaxial Compression

Qianqian Dong,Chengwang Xiong,Chunlei Ma,Huajian Wei 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.6

Extensive efforts have been made in the understanding of the failure characteristics of straight fissure, but the failure patterns of rock mass with intermittent non-straight fissures have not been examined comprehensively. To address this problem, the present study investigated the cracking behaviors of natural marble specimens containing double S-shaped fissures under compression. Seven types of coalescence patterns for S-shaped fissures are classified, two of which are firstly reported and featured by the occurrence of the self-coalescence phenomenon. It is found that the decrease of strength is accompanied by the internal crack at the stage of crack growth and propagation, following the occurrence of the external crack, at relatively large flaw and ligament angle. The numerical simulations with the corresponding parameters were carried out for comparison. This research provides helpful information for understanding the failure modes induced by crack propagation of intermittent double S-shaped fissures.

The Removal of Benzene and Toluene in Natural Gas with Cryogenic Liquid Propane: Effects and a Cyclic Purification Process

Dong Kai,Rong Qianqian,Xiao Ruirui,Gao Yunfei,Wang Fuchen 한국화학공학회 2024 Korean Journal of Chemical Engineering Vol.41 No.4

Liquefi ed natural gas production plants usually suff er from line blockage, which causes economic, environmental, and safety issues. The blockage, mainly caused by the solidifi cation of heavy hydrocarbons, should be avoided or mitigated by removing the impurities as thoroughly as possible. In this work, we proposed a scheme taking cryogenic liquefi ed propane as absorbent to absorb heavy hydrocarbons in the liquefi ed natural gas production process. This paper fi rst investigated freeze-out profi les of liquefi ed natural gas combined with marginal benzene and toluene by the ThermoFAST simulator, which showed that the precipitated solid tended to form under a low temperature, which posed challenges in purifi cation. Subsequently, the feasibility of using liquefi ed propane as an absorbent to remove benzene and toluene was studied using Aspen Plus. A cryogenic absorption and regeneration process for liquefi ed natural gas purifi cation was proposed, and factors infl uencing the performance were investigated. The results showed that the hydrocarbon impurities are removed more thoroughly at a high fl owrate of the recycled absorbent stream. The absorption process exhibited an apparent cooling eff ect mainly caused by the vaporization of liquefi ed propane to the gas phase, and the higher operation temperature impedes the vaporization process. For a better purifi cation eff ect, the system should be operated under a lower pressure or with a higher recycled absorption solution fl owrate. Based on the design simulation results, utilizing liquefi ed propane as an absorbent to remove heavy hydrocarbons is novel and promising for LNG purifi cation.

Substrate-Immersed Solvothermal Synthesis of Ordered SiO2/Ag Arrays as Catalytic SERS Substrates

Chang Liu,Qianqian Su,Li Li,Jie Sun,Jian Dong,Weiping Qian 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.5

In this work, we designed a simple substrate-immersed solvothermal route for the one-step synthesis of novel ordered SiO2/Ag arrays, employing SiO2 colloidal crystals as templates and alcohol as reducing agent. The Ag nanoparticles were uniformly deposited in situ onto SiO2 colloidal crystals, which exhibited high surface enhanced Raman spectroscopy (SERS) activity and uniform SERS intensity. It was found that ordered SiO2/Ag arrays could rapidly scavenge the absorbed-Nile blue A (NBA) molecules from the surfaces with the assistance of H2O2, while the SERS signals of NBA decreased sharply and almost completely disappeared within four minutes. This can be attributed to the superior catalytic activity of Ag nanoparticles. After five times of re-immersion and re-absorbing process of NBA, the substrates could still keep ~74.8% SERS intensity versus the original. The high activity and durability of the as-prepared SiO2/Ag SERS substrate endow them as a promising candidate for trace detection.

Performance of Rock-like Materials Containing Filled Kinked Fissures under Uniaxial Tension at Failure

Yulin Wu,Qianqian Dong,Jian He,Qiyang Chen 대한토목학회 2023 KSCE JOURNAL OF CIVIL ENGINEERING Vol.27 No.3

To investigate the tensile failure phenomenon of rock masses with filled natural defects, the mechanical behavior of 3D printed rock-like materials containing filled kinked fissures under uniaxial tension was identified. Different inclination angles of branch fissure were considered, and cement and gypsum slurry were selected as the infilling materials. It was found that filling materials enhanced the strength of the specimen, which presented to be cement filling > gypsum filling > no filling. The change of inclination angle of branch fissure had significant influence on the strength and failure mode of the specimen and the strength order was -135o> -45o > 90o and +45o > 90o > +135o. Two types of failure pattern, namely tip failure and non-tip failure, were observed in the experiment. Three types of newborn cracks were identified using a high-speed camera. The result achieved by using the digital image correlation technology indicated that different filling conditions led to the position change of high-strain zone. The displacement field of the filled specimen developed from being continuous to being discontinuous. Furthermore, the extended finite element method was adopted to simulate the filled and unfilled specimens, consistent with the experimental results. This study can provide a reliable reference for studying the tensile stress zones in rock exploration.

Economic Production of Probiotics from Kitchen Waste

Chunhua Yin,Xue Dong,Le Lv,Zhi-Guo Wang,Qianqian Xu,Xiaolu Liu,Hai Yan 한국식품과학회 2013 Food Science and Biotechnology Vol.22 No.suppl1

In the present work, a novel treatment method of kitchen waste for economic production of probiotics was investigated. This required the selection of suitable probiotic microorganisms. Based on the pure cultures of probiotic strains for the fermentation kitchen waste, 5 strains of microorganisms including 1 strain of Lactobacillus, 2strains of Bacillus, and 2 strains of yeast were selected,respectively. These probiotic microorganisms were mixed at the same ratio and cultured using the kitchen waste as culture medium at pH of 7.2 and temperature of 37oC. After 24 h, the total count of the viable cells reached 2.24×1010 CFU/g, which was higher than that obtained in any single probiotic strain pure culture. It was found that the presence of yeasts and Bacillus species enhanced the growth of Lactobacillus strain. Bench scale experiments were also done in a self-designed rotating drum type bioreactor. The experimental results indicate that there is a good possibility of utilizing kitchen waste for the economic production of probiotics.

Ganoderic acid A attenuates high‑fat‑diet‑induced liver injury in rats by regulating the lipid oxidation and liver inflammation

Fuli Liu,Kejian Shi,Jiaojiao Dong,Zhousheng Jin,Yiquan Wu,Yaoyao Cai,Tingting Lin,Qianqian Cai,Le Liu,Yujian Zhang 대한약학회 2020 Archives of Pharmacal Research Vol.43 No.7

Ganoderic Acid A (GA) has many pharmacologicaleffects such as anti-tumor, antibacterial, anti-inflammatory,and immunosuppressive effects. However, the protectiveeffect of GA on liver injury has not been reported. Thisstudy aimed to investigate the action of GA on insufficientmethionine and choline combined with high-fat diet (HFD)-induced non-alcoholic fatty liver disease (NAFLD) in rats. NAFLD model was established by insufficient methionineand choline combined with high fat feeding to rats. The levelsof Acetyl-CoA carboxylase, fatty acid synthase, sterolregulatory element binding protein, liver X receptors, AMPactivatedprotein kinase, peroxisome proliferator-activatedreceptor α, PPARg coactivator 1α and NF-κB pathway inthe liver were detected by western blot. The results of thisstudy demonstrated that the expression of GA can not onlysignificantly decrease the live weight and liver weight perbody weight of HFD mice, but also restore the alanine aminotransferase,aspartate aminotransferase, total bilirubinlevels, triglyceride and cholesterol in serum. In addition,the expression of GA increased the levels of high-densitylipoprotein cholesterol in serum, ameliorated pathologicalchanges and decreased NAS score of mice’s liver. In conclusion,the treatment with GA could improve NAFLD in ratsby regulating the levels of signaling events involved in freefatty acid production, lipid oxidation and liver inflammation.

Adiponectin Regulates Bone Marrow Mesenchymal Stem Cell Niche Through a Unique Signal Transduction Pathway: An Approach for Treating Bone Disease in Diabetes : Adiponectin Regulates BMSC Niche

Yu, Liming,Tu, Qisheng,Han, Qianqian,Zhang, Lan,Sui, Lei,Zheng, Leilei,Meng, Shu,Tang, Yin,Xuan, Dongying,Zhang, Jin,Murray, Dana,Shen, Qingping,Cheng, Jessica,Kim, Sung-Hoon,Dong, Lily Q.,Valverde, P Wiley (John WileySons) 2015 Stem Cells Vol.33 No.1

<P>Adiponectin (APN) is an adipocyte-secreted adipokine that exerts well-characterized antidiabetic properties. Patients with type 2 diabetes (T2D) are characterized by reduced APN levels in circulation and impaired stem cell and progenitor cell mobilization from the bone marrow for tissue repair and remodeling. In this study, we found that APN regulates the mobilization and recruitment of bone marrow-derived mesenchymal stem cells (BMSCs) to participate in tissue repair and regeneration. APN facilitated BMSCs migrating from the bone marrow into the circulation to regenerate bone by regulating stromal cell-derived factor (SDF)-1 in a mouse bone defect model. More importantly, we found that systemic APN infusion ameliorated diabetic mobilopathy of BMSCs, lowered glucose concentration, and promoted bone regeneration in diet-induced obesity mice. In vitro studies allowed us to identify Smad1/5/8 as a novel signaling mediator of APN receptor (AdipoR)-1 in BMSCs and osteoblasts. APN stimulation of MC3T3-E1 osteoblastic cells led to Smad1/5/8 phosphorylation and nuclear localization and increased SDF1 mRNA expression. Although APN-mediated phosphorylation of Smad1/5/8 occurred independently from adaptor protein, phosphotyrosine interaction, pleckstrin homology domain, and leucine zipper containing 1, it correlated with the disassembly of protein kinase casein kinase 2 and AdipoR1 in immunoprecipitation experiments. Taken together, this study identified APN as a regulator of BMSCs migration in response to bone injury. Therefore, our findings suggest APN signaling could be a potential therapeutic target to improve bone regeneration and homeostasis, especially in obese and T2D patients.</P>

Stress Field of Structures with Internal Cracks by 3D-ILC Technology: Experimental and Numerical Analysis

Haijun Wang,Haitang Qi,Xuhua Ren,Lei Tang,Qianqian Dong 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.1

Great achievements have been made regarding the stress field in the two-dimensional state, however the study of three-dimensional stress field visualization has still not been comprehensively examined. The model with internal cracks was prepared by the laser-medium interaction (3D-ILC), and with the aid of the photoelastic test technology, it visually showed the distribution characteristics of the stress field inside the rock with defects under the three-point bending test method. Primarily, based on the two-dimensional and three-dimensional stress optics law, the isometric fringes were converted into phase differences or optical path differences to visualize the stress field. Moreover, transparent glass, which had better transparency and brittleness closer to real rock was selected as the specimen material. Internal cracks changed the stress fringe distribution of the specimen, and the combination of 3D-ILC technology and photoelasticity provided a new way to visualize the three-dimensional stress field of brittle materials with internal cracks. Through the secondary development and utilization of ABAQUS finite element analysis software, the internal stress fields of brittle solid materials with horizontal internal cracks were visualized. Accurate characterization of the three-dimensional stress field of brittle solid materials has been a long-term goal pursued by researchers in the field of fracture, and it is also the basis and key to solving many practical engineering problems such as design, safety analysis and evaluation.