Experimental and Theoretical Study on the Behavior of Cold-formed Stainless Steel Stub Columns

Gan-Ping Shu,Baofeng Zheng,Xiaoming Shen 한국강구조학회 2013 International Journal of Steel Structures Vol.13 No.1

This paper presents an experimental investigation on the behavior of cold-formed stainless steel stub columns under axial compression. Nineteen hollow section specimens of seven section types were tested. Geometric imperfections, material properties and full-range load-displacement curves were obtained. The test strengths were compared with the four design strengths, which are respectively calculated by using the American specification, the European specification, the design method proposed by Rasmussen in 2004, and the design method proposed by Gardner in 2008. The American specification, the European specification, and the design method proposed by Rasmussen are generally conservative. While the design method proposed by Gardner is relatively accurate. Based on the comparisons, modifications to Winter equation were derived to involve both the factors of the corner enhancement of the cold-formed members and the nonlinear property of stainless steel. The modified Winter equation can predict the strengths with low scatter.

Serine proteinase (SP) and serine protease inhibitor (serpin) gene expression after hormone treatment in the silkworm Bombyx mori (Lepidoptera: Bombycidae)

GAN Li-ping,LIU Ren-hua,LI Yan-jie 한국응용곤충학회 2016 Journal of Asia-Pacific Entomology Vol.19 No.4

Many members of the Serine protease inhibitor (serpin) family participate in regulation by inhibiting Serine proteinases (SPs) or Serine protease homologs (SPHs) isozymes and maintaining the balance in the internal environment. SPs were expressed in the midguts of mid-fifth-instars and exhibited slightly higher expression in female compared to male late-fifth-instars. However, serpinsweremainly expressed in the silk glands, achieved a higher level of expression in the late fifth-instar and had an expression advantage in the males. The ratio of the cocoon shell was significantly higher in Jingsong compared to the other varieties in both the males and females, which was consistent with the higher mRNA and protein expression of Spi1 in the silk gland of Jingsong compared to the other varieties. These results reflected the positive correlation between TRP protein expression and the ratio of the cocoon shell and suggested that the higher mRNA and protein expression levels of the serpin gene wasmolecular evidence ofmore efficient silkmaterial synthesis. The SP/SPHand serpin genes presented different regulatory trends after treatment of the day 3 fifth-instar silkworm larvae with 20-hydroxyecdysone (20E) and juvenile hormone analogues (JHA). Themajority of the surveyed SP/SPH geneswere down-regulated and serpin geneswere up-regulated under treatmentwith the high concentration 20E. After JHA treatment, all of the investigated genes were up-regulated 48 h after treatment with JHA. The hormone regulatory effectwas primarily influenced by the developmental stage and the hormone dose. The tissue specificity and sex differences in the SP/ SPH and serpin genes implied that they participated in tissue-specific transcriptional regulation. The genes were expressed at different levels during different developmental periods and following hormone treatment. The results demonstrated that the genes played a role in scheduling and provided insights into the mechanismunderlying silk material formation and accumulation.

Impact of Inadequate Doses of Rituximab in the Treatment of Diffuse Large B Cell Lymphoma in Malaysian Patients

Gan, Gin Gin,Subramaniam, Rajaletchumy,Bee, Ping Chong,Chin, Edmund Fui Min,Abdul-Halim, Habibah,Tai, Mei Chee Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.4

Background: The current standard treatment for patients with newly diagnosed diffuse large B cell lymphoma (DLBCL) is rituximab combined with cyclophosphamide, doxorubicin, vincristine and prednisolone (CHOP). A significant number of patients were not treated with recommended dose of rituximab due to limited financial resources in Malaysia. This study evaluates the efficacy of R-CHOP like chemotherapy in Malaysian patients with DLBCL. Materials and Methods: The study comprised a retrospective analysis of patients with DLBCL treated at a single centre. The outcome was compared with patients who were treated with R-CHOP like and CHOP like chemotherapy. Patients who were treated with lower dose of rituximab was subanalysed for outcome. Results: A total of 86 patients who had CHOP-like chemotherapy were included. Only 39 (45%) patients had rituximab and only 12 (29%) patients had the recommended dose. The overall response (OR) and complete response (CR) rates were 88% and 81% respectively. There was no significant difference in OR and CR in patients who had rituximab and those without rituxmab. Those with International Prognostic Index (IPI) score of ${\leq}2$ had significant higher CR rate, progression free survival (PFS) and overall survival (p<0.001). Conclusions: The lack of significant improvement in CR and DFS in our patients may be due to an inadequate dose of rituximab.

The pivotal role of the NLRC4 inflammasome in neuroinflammation after intracerebral hemorrhage in rats

Gan Hui,Zhang Li,Chen Hui,Xiao Han,Wang Lu,Zhai Xuan,Jiang Ning,Liang Ping,Zheng Shuyue,Zhao Jing 생화학분자생물학회 2021 Experimental and molecular medicine Vol.53 No.-

The NLRC4 inflammasome, a member of the nucleotide-binding and oligomerization domain-like receptor (NLR) family, amplifies inflammation by facilitating the processing of caspase-1, interleukin (IL)–1β, and IL-18. We explored whether NLRC4 knockdown alleviated inflammatory injury following intracerebral hemorrhage (ICH). Furthermore, we investigated whether NLRC4 inflammasome activation can be adjusted by the regulator of G protein signaling 2/leucine-rich repeat kinase-2 pathway. Fifty microliters of arterial blood was drawn and injected into the basal ganglion to simulate the ICH model. NLRC4 small interfering RNAs (siRNAs) were utilized to knockdown NLRC4. An LRRK2 inhibitor (GNE7915) was injected into the abdominal cavity. Short hairpin (sh) RNA lentiviruses and lentiviruses containing RGS2 were designed and applied to knockdown and promote RGS2 expression. Neurological functions, brain edema, Western blot, enzyme-linked immunosorbent, hematoxylin and eosin staining, Nissl staining, immunoprecipitation, immunofluorescence assay and Evans blue dye extravasation and autofluorescence assay were evaluated. It was shown that the NLRC4 inflammasome was activated following ICH injury. NLRC4 knockdown extenuated neuronal death, damage to the blood-brain barrier, brain edema and neurological deficiency 3 days after ICH. NLRC4 knockdown reduced myeloperoxidase (MPO) cells as well as tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-1β and IL-18 following ICH. GNE7915 reduced pNLRC4 and NLRC4 inflammasome activation. RGS2 suppressed the interaction of LRRK2 and NLRC4 and NLRC4 inflammasome activation by regulating pLRRK2. Our study demonstrated that the NLRC4 inflammasome may aggravate the inflammatory injury induced by ICH and that RGS2/LRRK2 may relieve inflammatory injury by restraining NLRC4 inflammasome activation.

Nonlinear thermal post-buckling analysis of graphene platelets reinforced metal foams plates with initial geometrical imperfection

Yin-Ping Li,Gui-Lin She,Lei-Lei Gan,Hai-Bo Liu 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.5

Although some scholars have studied the thermal post-buckling of graphene platelets strengthened metal foams (GPLRMFs) plates, they have not considered the influence of initial geometrical imperfection. Inspired by this fact, the present paper studies the thermal post-buckling characteristics of GPLRMFs plates with initial geometrical imperfection. Three kinds of graphene platelets (GPLs) distribution patterns including three patterns have been considered. The governing equations are derived according to the first-order plate theory and solved with the help of the Galerkin method. According to the comparison with published paper, the accuracy and correctness of the present research are verified. In the end, the effects of material properties and initial geometrical imperfection on the thermal post-buckling response of the GPLRMFs plates are examined. It can be found that the presence of initial geometrical imperfection reduces the thermal post-buckling strength. In addition, the present study indicates that GPL-A pattern is best way to improve thermal post-buckling strength for GPLRMFs plates, and the presence of foams can improve the thermal post-buckling strength of GPLRMFs plates, the Foam- II and Foam- I patterns have the lowest and highest thermal post-buckling strength. Our research can provide guidance for the thermal stability analysis of GPLRMFs plates.

Stability Analysis of External Ramp Compensation on Valley V² Controlled Boost Converter

Haoyang Gan,Shengzhong He,Xiaoqiong He,Songrong Wu,Ping Yang,Minrui Leng 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

V² control has fast transient response so it has been widely used voltage regulator modules. Although valley V² control has been proposed to control boost converter, there still exist instability issues. To stabilize instability caused by small duty or equivalent series resistance of output capacitor, external ramp compensation has been used. However, there is no reference for choosing proper ramp slope. In this paper, a discrete iterative model of valley V² controlled boost converter with external ramp compensation is established. Based on the model, bifurcation behaviors under different duty cycle and ESR are observed as equivalent ramp slope increases. The orbit of converter transfers from chaos to multi-period then to period-1, consistent with maximal Lyapunov exponent. By analyzing loci of eigenvalues, stability boundaries in different operation regions are obtained to guide equivalent ramp slope design. Experimental prototype is also built up to verify the theoretical analysis.

Study on Residual Stress Distributions in Press-Braked Stainless Steel Sections

Baofeng Zheng,Gan-Ping Shu,Qinglin Jiang 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.5

The distribution of residual stresses is one of the substantial issues in determining mechanical behaviors of stainless steel structural members. Proper residual stress distribution models are necessary to include the residual stress infl uence in the analysis and design. Currently, the existing residual stress distribution model for press-braked stainless steel sections is either relatively complicated for the application, or only focuses on the longitudinal residual stress. In this study, a simplifi ed residual stress distribution model was proposed based on the analysis of the key mechanisms in the press-braking process that was assumed as two-stage (bending and rebounding) plane strain pure bending process. The stress–strain relationship was represented as a simplifi ed three–stage material model, and all the minor eff ects like the coiling and uncoiling, the material anisotropy, and the shift of neutral axis, etc. were neglected. Compared with test data, the predicted results by the proposed simplifi ed model indicate good agreement for specimens within the commonly used ratio of internal corner radius over the thickness ( r i / t ). Finite element models for the press-braking process were then developed in ABAQUS and validated using the available data from literature. A series of models with varied ratios of r i / t were analyzed. Simulation results indicate that the center of the corner region in the press-braked sections has the largest equivalent plastic strain and residual stresses. From the center to the edge, the equivalent plastic strain and residual stresses declined signifi cantly. As the ratios of r i / t become smaller and smaller, the neutral axis moves towards to the compression side and the proposed simplifi ed model gradually loses its prediction accuracy. Based on the theoretical and fi nite element analysis, the proposed simplifi ed model is applicable for press-braked stainless steel sections with r i / t ratios higher than 2.0.

Strength of Double Skin Steel-Concrete Composite Walls

Ying Qin,Gan-Ping Shu,Shenggang Fan,JinYu Lu,Shi Cao,Jian-Hong Han 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.2

Double skin steel-concrete composite walls have been increasingly used in civil engineering applications. However, the advantages of these walls have not been fully recognized due to the lack of appropriate technical guidelines for capacity design. In this paper, the local buckling strength of steel plate were firstly reviewed in terms of specifications incorporated in several modern codes. A methodology to predict the strength of steel plate with restraint of both concrete and shear studs was proposed based on the explicit solution for local buckling of steel plate in composite shear walls subjected to uniform axial compression and with elastically rotational restraint at loaded and unloaded edges. The results were compared with various previous experimental data and good agreement was observed. Furthermore, the load carrying capacity of composite walls was derived from the superposition of the contribution of steel plate and concrete. The predicted values from the proposed equations, together with the resulted determined from modern codes, were compared with the experimental results. It was found that both the proposed method and JEAG 4618 offer reasonable predictions while AISC 360 and KEPIC-SNG always underestimate the actual values.

Buckling analysis of elastically-restrained steel plates under eccentric compression

Ying Qin,Gan-Ping Shu,Er-Feng Du,Rui-Hua Lu 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.29 No.3

In this research, the explicit closed-form local buckling solution of steel plates in contact with concrete, with both loaded and unloaded edges elastically restrained against rotation and subjected to eccentric compression is presented. The Rayleigh-Rize approach is applied to establish the eigenvalue problem for the local buckling performance. Buckling shape which combines trigonometric and biquadratic functions is introduced according to that used by Qin <i>et al</i>. (2017) on steel plate buckling under uniform compression. Explicit solutions for predicting the local buckling stress of steel plate are obtained in terms of the rotational stiffness. Based on different boundary conditions, simply yet explicit local buckling solutions are discussed in details. The proposed formulas are validated against previous research and finite element results. The influences of the loading stress gradient parameter, the aspect ratio, and the rotational stiffness on the local buckling stress resultants of steel plates with different boundary conditions were evaluated. This work can be considered as an alternative to apply a different buckling shape function to study the buckling problem of steel plate under eccentric compression comparing to the work by Qin <i>et al</i>. (2018), and the results are found to be in consistent with those in Qin <i>et al</i>. (2018).

Material Enhancement Model for Austenitic Stainless Steel Sheets Subjected to Pre-stretching

Baofeng Zheng,Gan-Ping Shu,Rui-Hua Lu,Qinglin Jiang 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.5

Austenitic stainless steel has considerable strain hardening property, which can be utilized in the design of cold-formed stainless steel structures to eff ectively reduce project costs. Pre-stretching is a simple and fundamental cold-forming process. Material enhancement model developed for pre-stretching lays a basis for characterizing material properties in more complicated cold-forming process(e.g. cold-rolling and press-braking). In this study, a series of material tensile tests were performed to develop material enhancement models for austenitic stainless steel sheets subjected to pre-stretching. Austenitic stainless steel sheets were tensioned in six diff erent levels to introduce cold working into the sheets. Material properties of the sheets in two directions (i.e. along and perpendicular to the pre-stretching direction) were obtained through coupon tensile tests. To facilitate the development of the material enhancement models, a simplifi ed three-stage material model with six independent parameters was proposed. Enhancement model for each material parameter was developed with the plastic strain experienced in the pre-stretching process as a key factor. Key material parameters and full-range stress–strain curves at diff erent levels of pre-stretching were generated based on the proposed and the available predictive models in literatures. Comparisons of the generated material parameters and the stress–strain curves with the test ones show good agreement.