CFD study on hydraulic performance of subsurface flow constructed wetland: Effect of distribution and catchment area

Liwei Fan,Reti Hai,Zexiang Lu 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.5

A subsurface flow constructed wetland (SSFW) was simulated by using a commercial computational fluid dynamic (CFD) code (Fluent 6.22, Fluent Inc.). The liquid residence time distribution in the SSFW was obtained by the particle trajectory model. The simulation confirmed that the effect of the distribution and/or catchment area on the hydraulic efficiency is significant. An inappropriate horizontal distribution and/or catchment area can result in poor hydraulic efficiency. The hydraulic efficiency of the SSFW with the vertical distribution and/or catchment area can be kept at a high level (above 0.898). The design of the vertical distribution and/or catchment area in the SSFW is better than that of the horizontal. From the point of view of the engineering design, a small dimension distribution and/or catchment area in the SSFW is advisable, which maintains a considerable hydraulic efficiency of the SSFW (above 0.840), but also benefits the increase of the purge area.

Effects of silyl concentration, hydrogen concentration, ion flux, and silyl surface diffusion length on microcrystalline silicon film growth

Jingxiao Lu,Shutang Wen,Liwei Zhang,Yuxiao Li,Zhiyong Du 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.6

Two sets of μc-Si : H films as a function of pressure were fabricated by very-high-frequency plasma enhanced chemical vapor deposition (VHF-PECVD). Deposition rate, Raman crystallinity, and photo/dark conductivity were investigated under both low and high power conditions. A plasma fluid model and a surface hydride-dependent precursor diffusion model were constructed to understand the evolution of microcrystalline silicon under low and high power conditions. Silyl, hydrogen, ion flux, silyl surface diffusion length are believed to have much influence on film growth rate, crystallinity and photo electronic properties. But the interesting point is that under a certain condition one or more of these parameters dominate μc-Si : H growth, while other parameters have weak influence. Short-life radicals are found to be the possible major factor on the deterioration of photo sensitivity of μc-Si : H films.

Improvement of the Microstructure and Microhardness of AQ80 Magnesium Alloy by Repeated Upsetting-Extrusion

Yutian Fan,Liwei Lu,Tao Zhou,Hua Zhang,Fugang Qi,Min Ma,Zhiqiang Wu,Weitao Jia,Sha Zhang,Weiying Huang 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.10

In this work, a novel process of repeated upsetting-extrusion (RUE) was used to fabricate the AQ80 magnesium (Mg) alloy. The effects of deformation passes on the microstructure and microhardness of the RUEed AQ80 Mg alloy were studied. The results showed that {10–12} extension twins appeared in the sample after 1 pass of deformation compared to the initial sample, which divided the coarse grains and achieved the preliminary refinement of the grains. The grains were uniformly refined further with increasing RUE deformation passes, and after 3 passes, the average grain size was reduced from 27.4 to 3.0 μm. The grains were refined mainly by continuous dynamic recrystallization (CDRX), particle-stimulated nucleation (PSN), and discontinuous dynamic recrystallization (DDRX) mechanisms. After RUE deformation, the peak component of the texture was tilted by 0–20° toward the extrusion direction (ED) because of the increased activation of pyramidal < c + a > slip. The microhardness of the 3-pass RUE deformed sample increased by 12.9% compared to the initial sample. This is mainly attributable to fine-grained strengthening and second phase strengthening.

Major ginsenosides from Panax ginseng promote aerobic cellular respiration and SIRT1-mediated mitochondrial biosynthesis in cardiomyocytes and neurons

Huang, Qingxia,Lou, Tingting,Lu, Jing,Wang, Manying,Chen, Xuenan,Xue, Linyuan,Tang, Xiaolei,Qi, Wenxiu,Zhang, Zepeng,Su, Hang,Jin, Wenqi,Jing, Chenxu,Zhao, Daqing,Sun, Liwei,Li, Xiangyan The Korean Society of Ginseng 2022 Journal of Ginseng Research Vol.46 No.6

Background: Aerobic cellular respiration provides chemical energy, adenosine triphosphate (ATP), to maintain multiple cellular functions. Sirtuin 1 (SIRT1) can deacetylate peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) to promote mitochondrial biosynthesis. Targeting energy metabolism is a potential strategy for the prevention and treatment of various diseases, such as cardiac and neurological disorders. Ginsenosides, one of the major bioactive constituents of Panax ginseng, have been extensively used due to their diverse beneficial effects on healthy subjects and patients with different diseases. However, the underlying molecular mechanisms of total ginsenosides (GS) on energy metabolism remain unclear. Methods: In this study, oxygen consumption rate, ATP production, mitochondrial biosynthesis, glucose metabolism, and SIRT1-PGC-1α pathways in untreated and GS-treated different cells, fly, and mouse models were investigated. Results: GS pretreatment enhanced mitochondrial respiration capacity and ATP production in aerobic respiration-dominated cardiomyocytes and neurons, and promoted tricarboxylic acid metabolism in cardiomyocytes. Moreover, GS clearly enhanced NAD⁺-dependent SIRT1 activation to increase mitochondrial biosynthesis in cardiomyocytes and neurons, which was completely abrogated by nicotinamide. Importantly, ginsenoside monomers, such as Rg1, Re, Rf, Rb1, Rc, Rh1, Rb2, and Rb3, were found to activate SIRT1 and promote energy metabolism. Conclusion: This study may provide new insights into the extensive application of ginseng for cardiac and neurological protection in healthy subjects and patients.

Effects of the Charge Ions Strength on the Swelling of Organic–Inorganic Nanogels

Qin Yu,Xiangguo Lu,Jing Wang,Qi Guo,Liwei Niu 대한화학회 2016 Bulletin of the Korean Chemical Society Vol.37 No.7

The swelling behavior and swelling mechanism of hydrogels can be greatly affected by the charge strength of ions in them. To investigate such effects, we prepared two gels: a carboxylic acid gel (CAG) and a poly(2-acrylamide–methyl propane sulfonic acid) gel (SAG) based on starchy polyacrylamide (PAM) nanocomposite gels, both with montmorillonite, which underwent in situ intercalation, and used them as probes in swelling experiments. The equilibrium swelling rates (ESRs) of the hydrogels in both salt water and acidic water strongly depended on the charge strength of the ions in the chains. SAG had a higher ESR than CAG at the same mole ratio of polymer/water, which is attributed to the greater electrostatic repulsion between the strong electrolyte ions of SAG. Both water salinity and hydrogen ion contact of the hydrogels weakened ESR with the enhancement of charge ionic strength. The downward trend of ESR with increasing concentration of salt or hydrogen ions became weaker in SAG compared to CAG, which is attributed to the shielding and deprotonation effects of the strong electrolyte ions. Regarding the swelling mechanism, the chain relaxation occurred in neutral and acidic solutions for SAG and in neutral and weak acidic solutions for CAG, but water diffusion dominated in strong acidic solutions for CAG, leading to different swelling behaviors.

Effects of positive and negative stretching on the structure and properties of polyacrylonitrile fibers in the pre-oxidation process

Liang Wang,Wei Lu,Li Zhang,Liwei Xue,Seung-Kon Ryu,Ri-guang Jin 한국탄소학회 2011 Carbon Letters Vol.12 No.2

Polyacrylonitrile (PAN) fibers were pre-oxidized in a temperature range of 180-275℃. The effects of positive and negative stretching on the structure and morphology of PAN fiber in the pre-oxidation process were studied by FTIR spectroscopy, XRD, and SEM. Mechanical property changes were also investigated. No changes in the movement and intensity of functional groups of PAN fibers were caused by positive stretching of up to 10% and negative stretching down to -8%. The crystal structure can be affected by the positive stretching and negative stretching. The maximum strength is 479.81 MPa when the stretching is positive, and the maximum strength is 420.55 MPa when the stretching is negative.

Influence of In-Plane Simple Shear Strain on the Grain Orientation Regulation and Stretch Formability of Pre-twinned AZ31 Magnesium Alloy Sheet

Liangliang Xue,Lifei Wang,Pengbin Lu,Qiang Zhang,Hua Zhang,Guangsheng Huang,Liwei Lu,Liuwei Zheng,Hanuma Reddy Tiyyagura,Hongxia Wang,Shuyong Jiang,Kwang Seon Shin 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.10

Pre-twin is widely accepted as an efficient method for weakening the basal texture to improve the plasticity of magnesium alloys, particularly for formability. However, the enhancement is limited since the largest Schmid factor (SF) of basal slip cannot be achieved. In-plane simple shear strain is used to control the twin orientation in accordance with Schmid law to further decrease the basal texture and improve the formability of the Mg alloys sheet. Consequently, secondary regulation of initial twin orientation (SRITO) technology, a novel combination procedure, was developed. In this method, the AZ31 Mg alloys sheet is compressed to pre-twins with various volumes (1%, 3%, and 5%), then the twin orientation is regulated by in-plane simple shear strain for the second time. Compared with the as-received sample, the average fracture elongation of the annealed sample with the best properties improves from 15.3 to 28.8%, and the Erichsen value increases from 2.8 to 6.1 mm due to the regulation of twin orientation.

MicroRNA Regulation in Systemic Lupus Erythematosus Pathogenesis

Yan, Sheng,Yim, Lok Yan,Lu, Liwei,Lau, Chak Sing,Chan, Vera Sau-Fong The Korean Association of Immunobiologists 2014 Immune Network Vol.14 No.3

MicroRNAs (miRNAs) are endogenous small RNA molecules best known for their function in post-transcriptional gene regulation. Immunologically, miRNA regulates the differentiation and function of immune cells and its malfunction contributes to the development of various autoimmune diseases including systemic lupus erythematosus (SLE). Over the last decade, accumulating researches provide evidence for the connection between dysregulated miRNA network and autoimmunity. Interruption of miRNA biogenesis machinery contributes to the abnormal T and B cell development and particularly a reduced suppressive function of regulatory T cells, leading to systemic autoimmune diseases. Additionally, multiple factors under autoimmune conditions interfere with miRNA generation via key miRNA processing enzymes, thus further skewing the miRNA expression profile. Indeed, several independent miRNA profiling studies reported significant differences between SLE patients and healthy controls. Despite the lack of a consistent expression pattern on individual dysregulated miRNAs in SLE among these studies, the aberrant expression of distinct groups of miRNAs causes overlapping functional outcomes including perturbed type I interferon signalling cascade, DNA hypomethylation and hyperactivation of T and B cells. The impact of specific miRNA-mediated regulation on function of major immune cells in lupus is also discussed. Although research on the clinical application of miRNAs is still immature, through an integrated approach with advances in next generation sequencing, novel tools in bioinformatics database analysis and new in vitro and in vivo models for functional evaluation, the diagnostic and therapeutic potentials of miRNAs may bring to fruition in the future.

PERFORMANCE IMPROVEMENT OF AN ADSORPTION CHILLER USING COMPOSITE ADSORBENT, SILICA GEL IMPREGNATED WITH LITHIUM CHLORIDE, PAIRED WITH METHANOL AS THE ADSORBATE

FRED T. ISHUGAH, RUZHU WANG,LIWEI WANG,ZISHENG LU 대한설비공학회 2014 International Journal Of Air-Conditioning and Refr Vol.22 No.2

This study aimed at analyzing different operation strategies to improve the performance of anew type adsorption chiller employing a novel composite adsorbent, silica gel impregnated withlithium chloride, paired with methanol as the adsorbate. The chiller's experimental test resultsshowed an average Specific. Cooling Power (SCP) and Coeffient of Performance (COP) of286 W/kg and 0.48, respectively. This was when the average hot water inlet temperature,cooling water inlet temperature, and chilled water inlet temperature were 83C, 26C and 15C,respectively. In addition, the corresponding mass flow rates were 0.22, 0.39 and 0.09 kg/s, respectively. Despite the fact that the average SCP and COP, were rather satisfactory, analysis ofexperimental results conducted with different cycle times, inlet hot water temperatures, and hotwater flow rates showed that a much better performance could be achieved. Experimentalresults indicated the following: (1) the COP increased while the SCP decreased with increasedcycle time, (2) both the COP and the SCP increased with increase in heat and mass recoverytime to an optimal time then started to decrease as heat and mass recovery time increasedbeyond the optimal time, (3) both the cooling power and COP generally increased with increasein inlet hot water temperature at a relatively higher value from 60C to about 90C beyondwhich the incremental value started diminishing, and, (4) increase in mass flow rates producedhigher cooling power with decreased COP while decrease in mass flow rates of hot water producedlower cooling power with increased COP. This paper therefore recommends an adsorption/desorption time, heat and mass recovery time, inlet hot water temperature, and hot watermass flow rate of 780 s, 60 s, 83C, and 0.22 kg/s as appropriate to give the best chiller performancefor refrigeration.

MicroRNA Regulation in Systemic Lupus Erythematosus Pathogenesis

Sheng Yan,Lok Yan Yim,Liwei Lu,Chak Sing Lau,Vera Sau-Fong Chan 대한면역학회 2014 Immune Network Vol.14 No.3

MicroRNAs (miRNAs) are endogenous small RNA molecules best known for their function in post-transcriptional gene regulation. Immunologically, miRNA regulates the differentiation and function of immune cells and its malfunction contributes to the development of various autoimmune diseases including systemic lupus erythematosus (SLE). Over the last decade, accumulating researches provide evidence for the connection between dysregulated miRNA network and autoimmunity. Interruption of miRNA biogenesis machinery contributes to the abnormal T and B cell development and particularly a reduced suppressive function of regulatory T cells, leading to systemic autoimmune diseases. Additionally, multiple factors under autoimmune conditions interfere with miRNA generation via key miRNA processing enzymes, thus further skewing the miRNA expression profile. Indeed, several independent miRNA profiling studies reported significant differences between SLE patients and healthy controls. Despite the lack of a consistent expression pattern on individual dysregulated miRNAs in SLE among these studies, the aberrant expression of distinct groups of miRNAs causes overlapping functional outcomes including perturbed type I interferon signalling cascade, DNA hypomethylation and hyperactivation of T and B cells. The impact of specific miRNA-mediated regulation on function of major immune cells in lupus is also discussed. Although research on the clinical application of miRNAs is still immature, through an integrated approach with advances in next generation sequencing, novel tools in bioinformatics database analysis and new in vitro and in vivo models for functional evaluation, the diagnostic and therapeutic potentials of miRNAs may bring to fruition in the future.