Fire Resistance Prediction of Load Bearing Cold-Formed Steel Walls Lined with Gypsum Composite Panels

An innovative load-bearing cold-formed steel (CFS) wall lined with gypsum composite panels was developed with the goal of improving the construction efficiency and fire performance of these walls for applications in mid/high-rise buildings. The gypsum composite panel was formed by sandwiching insulation and plasterboard strips between two layers of gypsum plasterboards. Subsequently, the predicted fire resistance of these CFS walls was predicted based on our previously developed and experimentally validated modeling method. The degenerated material properties of the cold-formed steel and thermal physical property of the gypsum plasterboard and aluminum silicate wool were obtained from our pervious experimental investigations and used as the basic input parameters in the present fire resistance modeling. The results showed that the fire performance of the CFS walls lined with gypsum composite panels improved greatly. The configuration details and corresponding design load levels were also determined for the CFS walls with a fire resistant rating of 120 and 150 min

Numerical Simulation of the Thermal and Mechanical Behavior of Cold-Formed Steel Composite Floor under Fire Conditions

Cold-formed steel (CFS) building structures are generally acknowledged as green and industrialized buildings, and the fire resistance behavior has become an important issue. Previous studies were mainly to investigate the fire performance of load-bearing CFS walls lined with different panels. Based on the finite element (FE) software package, ABAQUS, this paper presented a numerical simulation on a new CFS channel joist – ALC (autoclaved lightweight concrete) composite floor under fire conditions. Finally, the present numerical simulation of CFS composite floor in fire was compared with previous full-scaled fire experiments of such floors. The results showed that the temperature progression of the CFS floor section was well predicted with acceptable accuracy. The time-dependent vertical deflection of the CFS floor was well described and the fire resistance time of CFS floor system was well predicted with an underestimation of less than 6% and an overestimation of less than 10%

Impact of Wall Configurations on Seismic Fragility of Steel-Sheathed Cold-Formed Steel-Framed Buildings

Seismic fragility of steel-sheathed cold-formed steel-framed (CFSF) structures is scarcely investigated; thus, the information for estimation of seismic losses of the steel-sheathed CFSF buildings is insufficient. This study aims to investigate the seismic fragility of steel-sheathed CFSF buildings with different wall configurations. Analytic models for four 2-story steel-sheathed CFSF buildings are established based on shaking table tests on steel-sheathed CFS walls. Then, a group of fragility curves for these buildings are generated. The results show that the thickness of steel sheathing and the fastener spacing of the wall have significant impact on seismic fragility of steel-sheathed CFSF buildings. The seismic fragility of the CFSF building can be reduced by increasing the thickness of steel sheathing or decreasing the fastener spacing. By increasing the thickness of steel sheathing, the reduction on probability is more obvious for the CP limit. It is also found that the exceeding probability is approximately linear with fastener spacing, with a slope in the range from 0.25%/mm to 0.50%/mm

Dynamic Nonlinearity and Nonlinear Single-Degree-Of-Freedom Model for Cable Net Glazing

The Nonlinear Vibration Differential Equation and Vibration Frequency of Cable Net Glazing Subject to Earthquake Loading Was Determined, and a Geometrically Nonlinear Single-Degree-Of-Freedom Model for Cable Net Glazing Was Developed. the Nonlinear Response Spectra Were Established, and Nonlinear Time History Analysis with Finite Element (FE) Models Was Conducted to Verify Them. the Nonlinear Vibration Differential Equation and Frequency Obtained as Described in This Paper Provide a Basis for the Nonlinear Single-Degree-Of-Freedom Model for Cable Net Glazing. the Analytical Formula for the Nonlinear Frequency with a Simplified Expression is Highly Precise and Convenient for Use in Engineering Practice. for Larger-Amplitude Seismic Waves, the Difference between the Linear and Nonlinear Response Spectra Are More Obvious. as the Natural Period of Cable Net Glazing is Always Less Than 2 S, the Linear Response Spectra in the Chinese Code for the Seismic Design of Buildings Can Be Used in the Seismic Design of Cable Net Glazing as an Approximation Rather Than the Nonlinear Response Spectra of Cable Net Glazing. © 2013 American Society of Civil Engineers

SREBP-1a activation by HBx and the effect on hepatitis B virus enhancer II/core promoter

Hepatitis B virus (HBV) X protein (HBx) plays an important role in HBV pathogenesis by regulating gene expression. Sterol regulatory element binding protein-1a (SREBP-1a) is a key transcriptional factor for modulating fatty acid and cholesterol synthesis. Here we demonstrated that HBx increased mature SREBP-1a protein level in the nucleus and its activity as a transcription factor. We further showed that the up-regulation of SREBP-1a by HBx occurred at the transcriptional level after ectopic expression and in the context of HBV replication. Deletional analysis using SREBP-1a promoter revealed that the sequence from -436 to -398 in the promoter was required for its activation by HBx. This promoter region possesses the binding sequences for two basic leucine zipper (b-ZIP) transcription factors, namely C/EBP and E4BP4. Mutagenesis of the binding sequences on the SREBP-1a promoter and ectopic expression experiments demonstrated that C/EBPα enhanced SREBP-1a activation by HBx, while E4BP4 had an inhibitory effect. C/EBPα was able to significantly reverse the inhibitory activity of E4BP4 on SREBP-1a promoter. These results demonstrated that HBx activates SREBP-1a activity at the transcription level through a complex mechanism involving two bZIP transcription factors C/EBP and E4BP4 with C/EBP being the dominant positive factor. Finally, we showed that knocking down SREBP-1 abolishes HBV enhancer II/core promoter activation by HBx.Fil: Qiao, Ling. University Of Saskatchewan; CanadáFil: Wu, Qi. University Of Saskatchewan; CanadáFil: Lu, Xinya. University Of Saskatchewan; CanadáFil: Zhou, Yan. University Of Saskatchewan; CanadáFil: Fernández Alvarez, Ana Julia. Consejo Superior de Investigaciones Cientificas; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Ye, Lihong. Nankai University; ChinaFil: Zhang, Xiaodong. Nankai University; ChinaFil: Han, Jihong. Nankai University; ChinaFil: Casado, Marta. Consejo Superior de Investigaciones Cientificas; EspañaFil: Liu, Quiang. University Of Saskatchewan; Canad

The tumor suppressive role of CAMK2N1 in castration-resistant prostate cancer.

Prostate cancer at advanced stages including metastatic and castration-resistant cancer remains incurable due to the lack of effective therapies. The CAMK2N1 gene, cloned and characterized as an inhibitor of CaMKII (calcium/calmodulin-dependent protein kinase II), has been shown to affect tumorigenesis and tumor growth. However, it is still unknown whether CAMK2N1 plays a role in prostate cancer development. We first examined the protein and mRNA levels of CAMK2N1 and observed a significant decrease in human prostate cancers comparing to normal prostate tissues. Re-expression of CAMK2N1 in prostate cancer cells reduced cellular proliferation, arrested cells in G0/G1 phases, and induced apoptotic cell death accompanied by down-regulation of IGF-1, ErbB2, and VEGF downstream kinases PI3K/AKT, as well as the MEK/ERK-mediated signaling pathways. Conversely, knockdown of CAMK2N1 had a significant opposite effects on these phenotypes. Our analyses suggest that CAMK2N1 plays a tumor suppressive role in prostate cancer cells. Reduced CAMK2N1 expression correlates to human prostate cancer progression and predicts poor clinical outcome, indicating that CAMK2N1 may serve as a biomarker. The inhibition of tumor growth by expressing CAMK2N1 established a role of CAMK2N1 as a therapeutic target

Rif1 Maintains Telomere Length Homeostasis of ESCs by Mediating Heterochromatin Silencing

SummaryTelomere length homeostasis is essential for genomic stability and unlimited self-renewal of embryonic stem cells (ESCs). We show that telomere-associated protein Rif1 is required to maintain telomere length homeostasis by negatively regulating Zscan4 expression, a critical factor for telomere elongation by recombination. Depletion of Rif1 results in terminal hyperrecombination, telomere length heterogeneity, and chromosomal fusions. Reduction of Zscan4 by shRNA significantly rescues telomere recombination defects of Rif1-depleted ESCs and associated embryonic lethality. Further, Rif1 negatively modulates Zscan4 expression by maintaining H3K9me3 levels at subtelomeric regions. Mechanistically, Rif1 interacts and stabilizes H3K9 methylation complex. Thus, Rif1 regulates telomere length homeostasis of ESCs by mediating heterochromatic silencing