Effects Of Tension Forces Research Articles

Thermo-physical properties of non-linear radiative flow of magnetized Ellis fluid comprising analysis of oxytactic microorganisms and nano-enhanced phase materials

The basic aim of existing analysis is to scrutinize the two-dimensional flow regime of Ellis model under the consideration of magnetic field. The effect of thermophoresis as well as Brownian motion for Ellis model with the impacts of parameters like thermal radiation, bioconvection of microorganisms and viscous dissipation are also deliberated. On the other hand, the features of bioconvection have been systematically examined for its extensive uses in microbial developed oil recovery, gas-bearing alluvial basin, bio-microsystems and oil modeling. Under the effects of tension force, viscoelastic materials change according to viscoelastic and elastic illustration. Here we considered it due to hydro-dynamics unevenness and designs within suspension of subjective spinning microbes. Therefore, this paper presents a theoretical and computational evaluation of the unsteady 2D Bioconvection flow of Ellis fluid, which has non-linear radiation features as well as gyro-tactic microorganisms, illuminating the novelty of the work. Here, convective B. Cs are used for the current study, coupled PDEs are changed into coupled ODEs by using some suitable B. Cs and similarity conditions. The acquired ODEs are numerically solved by using bvp4c scheme. Here Physical effects concerning all such parameters are studied in detail and represented graphically. We found that increasing behavior of temperature for higher value of Brownian movement and thermophoresis parameter whereas fall in Prandtl number. The gyrotactic microbes result in reduction for rising values of Peclet number.

Experimental and FE analysis of the behavior of steel column base connections under tension and bending moment

Most design procedures represent the steel base connection by assuming either a perfectly hinged or a fully rigid connection. However, these kinds of connections are, in fact, semi-rigid or flexible and their actual behavior is complicated. Most of the previous studies investigated these base connections experimentally under moments and axial compression only, which is completely different in the case of axial tension and moment. Therefore, experimental and numerical investigations with variable base plate thicknesses and diameters and arrangements of the anchor bolts were carried out to verify the behavior of this kind of base connection under axial tension and moment. Full-scale steel columns with hinged base plate connections were tested under the effect of two simultaneous actions, axial tension force and bending moment. Moreover, Finite Element (FE) models were developed and verified against the experimental results to conduct a parametric study. The investigated parameters were the base plate thickness and anchor bolt diameter and arrangement. The base plate connections under the effect of axial tension with moment instead of axial compression caused reductions in the rotational stiffness up to 99%. In addition, using only two bolts in this type of connection concentrated stresses on the base plate that led to big deformations. The small base plate thickness deformed easily under the effect of tension force which induced big initial gaps between the steel base plate and the Base beam and subsequently decreased the moment resistance and rotational stiffness of the base plate connection. The big elongation of the anchor bolts with small diameters increased the gap between the steel plate and the Base beam.

Crystallization and mechanical properties of carbon nanotube/continuous carbon fiber/metallocene polypropylene composites

In this work, a high fluidity polypropylene prepared with the metallocene catalyst (mPP) was used as matrix, carbon nanotube (CNT) and continuous carbon fiber (CCF) were added to prepare composites, and their mechanical properties, melting and crystallization behavior were investigated. In the mechanical properties, the effects of tension force in the preparation process and compatibilizer maleic anhydride grafted polypropylene (MAPP) on the tensile strength of the composites were researched. The results show that the tensile strength of the composites increases first and then decreases with the increase of tractive force. In addition, the melting and crystallization behaviors and dynamic mechanical behaviors of mPP, CNT/mPP and CNT/CCF/mPP composites were characterized and studied by a differential scanning calorimetry (DSC) and dynamic mechanical analyzer (DMA). The results show that the melting point (T m), crystallization temperature (T c) and storage modulus (E′) of CNT/mPP are all increased by adding 1 wt% CNT, especially the T c is increased by 8.8 °C. It shows that after CNT was added to mPP as inorganic carbon material, it plays a prominent role in heterogeneous nucleation. After CCF was composited with CNT/mPP, the composites with CCF content of 30 and 42 wt% were prepared, and their T m, T c, crystallinity (X c) and E′ were all improved, especially E′ was greatly improved, such as the initial E′ was increased by 5.64 and 11.74 times. Even at the end of the curve, the E′ of the composites with CF is still significantly higher than that of mPP and CNT/mPP. It indicates that adding CCF will greatly improved the deformation resistance and load deformation temperature of mPP.

多楔带张紧力对当量摩擦系数的影响规律

多楔带张紧力对当量摩擦系数的影响规律

Tension force-induced ATP promotes osteogenesis through P2X7 receptor in osteoblasts.

Orthodontic tooth movement induces alveolar bone resorption and formation by mechanical stimuli. Force exerted on the traction side promotes bone formation. Adenosine triphosphate (ATP) is one of the key mediators that respond to bone cells by mechanical stimuli. However, the effect of tension force (TF)-induced ATP on osteogenesis is inadequately understood. Accordingly, we investigated the effect of TF on ATP production and osteogenesis in MC3T3-E1 cells. Cells were incubated in the presence or absence of P2X7 receptor antagonist A438079, and then stimulated with or without cyclic TF (6% or 18%) for a maximum of 24 h using Flexercell Strain Unit 3000. TF significantly increased extracellular ATP release compared to control. Six percent TF had maximum effect on ATP release compared to 18% TF and control. Six percent TF induced the expression of Runx2 and Osterix. Six percent TF also increased the expression of extracellular matrix proteins (ECMPs), ALP activity, and the calcium content in ECM. A438079 blocked the stimulatory effect of 6% TF on the expression of Runx2, Osterix and ECMPs, ALP activity, and calcium content in ECM. This study indicated that TF-induced extracellular ATP is released in osteoblasts, suggesting that TF-induced ATP promotes osteogenesis by autocrine action through P2X7 receptor in osteoblasts. J. Cell. Biochem. 116: 12–21, 2015. © 2014 The Authors. Journal of Cellular Biochemistry published by Wiley Periodicals, Inc.

Effects of Tension Force on Proliferation and Differentiation of Human Periodontal Ligament Cells Induced by Lipopolysaccharides

Human periodontal ligament cells (hPDLCs), with the potential for multi-directional differentiation and reproduction, are the target cells of orthodontic tooth movement. The aim of this study was to examine the effect of mechanical tension force and lipopolysaccharides (LPS) on hPDLCs and whether they induce proliferative and differentiated characters in vitro. Tension force was applied to hPDLCs stimulated with and without LPS for 24 hrs. Real-time polymerase chain reaction (qPCR) was carried out to analyze the mRNA expression of Cyclin 2 (CCND2), WNT1 inducible signaling pathway protein 1 (WISP1), runt-related transcription factor 2 (RUNX2) and alkaline phosphatase (ALP). Analysis of variance (ANOVA) was used for statistical analysis. Significant differences were indicated by P < 0.05. The results showed that tension force promoted the mRNA expression of both the proliferation-related genes (CCND2 and WISP1) and differentiation-related genes (RUNX2 and ALP), and that both were enhanced by the simulation of LPS. In addition, the relative expression ratios CCND2/RUNX2 and CCND2/ALP both increased significantly after the application of tension, and this effect was further enhanced by LPS. All results indicated that with the assessed level of mechanical force loading, tension could promote both the proliferation and differentiation of hPDLCs, which could be enhanced by LPS, and that proliferation is promoted to a greater extent than differentiation. These findings may be valuable for understanding the importance of the application of suitable mechanical force in periodontal remodeling, especially in the process of orthodontic tooth movement with inflammation.

Effect of tension-force on plasminogen activator activity from human periodontal ligament cells.

The plasminogen activator (PA)-plasmin proteolytic system has recently received considerable attention because of its participation in a wide variety of biological activities and in pathological conditions involving tissue destruction. Excessive mechanical stress such as occlusal trauma is associated with alveolar bone loss in severe periodontitis. Therefore, mechanical stress may involve degradation of the extracellular matrix by occlusal trauma through activation of the PA-plasmin proteolytic system. We examined the effects of mechanical stress on PA activity, gene expressions of tissue type (t) PA, urokinase type (u) PA and PA inhibitor-1 (PAI-1) in human PDL cells. Human PDL cells were cultured on flexible-bottomed culture plates and placed on a Flexercell Strain Unit. The cells were flexed at 6 cycles (5 s strain, 5 s relaxation) at 9% and 18% elongation for 5 d. Application of tension-force induced significantly higher PA activity in stressed PDL cells than in non-stressed controls, and did so in a time- and magnitude-dependent manner (p < 0.001, ANOVA). Western-blot analysis revealed that the high level of activity was due to tPA and not uPA. Gene expression of tPA mRNA in stressed PDL cells, as examined by RT-PCR, increased on d 5. These findings suggest that tPA may be involved in periodontal metabolism in response to mechanical stress.