Mechanical Load

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Bone formation in rabbit cancellous bone explant culture model is enhanced by mechanical load

Bone formation in rabbit cancellous bone explant culture model is enhanced by mechanical load

In addition, we also found a close association between COL-1, OPG and BMP-2 ex- pression and mechanical load on cancellous bone explant models in this research. Pre- vious studies have revealed that Osteogenic differentiation procedurally experiences gene expression of ALP, OPG, COL-1, and BMP-2 in a time-dependent manner. COL- 1 is the most abundant protein in bone and the main composition of bone matrix, its expression is complexly regulated by a set of different factors. Under 3D dynamic load condition, COL-1 could be up-regulated after 3 days. OPG secreted by osteoblasts is a sort of glycoprotein which can combine to osteoclast surface-factor NF-κβ receptor ac- tivator (RANK) competing with OPGL which is cognate ligand of OPG, both OPG and OPGL can highly express in osteoblasts. RANK combining with OPG can block differ- entiation and proliferation of osteoclasts, which will reduce generation of bone absorp- tion, additionally, osteoclast surface F-actin which is bound to OPG can directly inhibit bone resorption activity of mature osteoclasts; and BMP-2 plays an important role in the regulation of bone formation and remodeling, which can improve bone formation in bone tissue engineering, since all of them are secreted during differentiation or pro- liferation of osteoblasts [26-34]. Expressions of COL-1, OPG and BMP-2 protein and Table 7 OPG and BMP-2 effect of bone explant models ( n =3)

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Mechanosensation and mechanical load modulate the locomotory gait of
swimming C  elegans

Mechanosensation and mechanical load modulate the locomotory gait of swimming C elegans

C. elegans provides a rare opportunity to analyze locomotory gait that connects our understanding of the genetics and neurobiology of mechanosensory transduction (Goodman and Schwarz, 2003) at the molecular level with the mechanics of low-Reynolds number hydrodynamics at the organismal level (Purcell, 1977). Here, we have taken advantage of these tools to isolate and quantify specific effects of mechanosensory and mechanical load on the swimming gait. Our analysis highlights new questions: C. elegans opts to use the same spatial form when swimming in fluids with different viscosity, but does it do so because only certain spatial forms of locomotory gait are hardwired into its motor systems or because the worm is using biochemical feedback to maximize hydrodynamic efficiency? Mechanosensory input affects the temporal frequency of the swimming gait, but why and how does this happen without affecting the spatial form of the swimming gait? In any case, our analysis of the physical and sensory determinants of the swimming gait provides a framework for continued investigation of such questions within a tractable model system.

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The effect of mechanical load on dermal fibroblast collagen deposition and organisation

The effect of mechanical load on dermal fibroblast collagen deposition and organisation

load, compared to unloaded controls, and these levels were sustained for the following 24 hours o f culture. However, the o2 subunit was expressed at higher levels after 16 hours in loaded versus control cultures, and then returned to control levels by the 24 and 48 hours time points. This transient recruitment o f ct2 to the cell surface is very interesting and has not been previously reported in the context o f load responses or indeed growth factor responses. The recruitment o f (31 integrins was not seen in response to load in the data presented in this chapter. This finding is in agreement w ith a recent study in endothelial cells, which shows no change in (31 expression in response to cyclical mechanical load over 24 hours. This report has also demonstrated no change in total or cell surface oc2 or a5 integrin subunit (Yano et al, 1997). However, changes in organisation on the cell surface into linear patterns were reported for p l , a5 and oc2 subunits, and increase in the phosphorylation o f focal adhesion proteins were also observed (Yano et al, 1997). Therefore, in this study, despite exhibiting no change in expression o f integrins in response to load, it would appear that both o 2 p l and a 5 p l may be responsive to stretch merely through the reorganisation and subsequent increased signalling to the cell nucleus.

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Response of Modular Composite Walls to Combined Thermal & Mechanical Load

Response of Modular Composite Walls to Combined Thermal & Mechanical Load

The economic benefits of SC structural systems have generated increased interest into their applicability to a wide array of possible future uses, including those involving blast/missile resistant designs. The purpose of this paper is to provide experimental results and conclusions from a test program that sought to explore the viability of SC modules as nuclear power plant steam generator compartment walls. Literature survey indicates that there is ample test/analytical data on the behavior of SC walls subjected to mechanical loads, but not on combined thermal and mechanical load. Concrete tends to become “fully cracked” when subjected to high temperature gradient (i.e., concrete ceases to contribute in compression). Under such loading environment, it is vital that the steel plates continue to act as “bonded rebar” (i.e., not experience failure due to local buckling and/or shear connector) and that the section maintains sufficient resistance to through-thickness shear. Furthermore, the wall should be able to resist beyond-design-basis pressure loads without risking an imminent/brittle collapse mode. Finally, simple design/analysis tools are necessary to model the SC wall behavior subjected to simultaneous thermal and pressure load. With this in mind, a test setup (described below) and a fiber model analytical approach were devised to study and validate the SC wall application.

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Effects of Wnt3A and mechanical load on cartilage chondrocyte homeostasis

Effects of Wnt3A and mechanical load on cartilage chondrocyte homeostasis

Articular cartilage functions to withstand mechanical load and provides a lubricating surface for frictionless movement of joints. However, cartilage degeneration can develop, leading to the progressive erosion of struc- tural integrity and eventual loss of functional perfor- mance as characterised by the pathology of OA. Excessive or abnormal joint loading patterns can initiate OA cartilage pathology [3,12]. Further, a functional SNP resulting in an Arg324Gly substitution in sFRP3 (FrzB) has been identified as a susceptibility locus in associa- tion with hip OA [4]. The mutation in sFRP3 (FrzB) reduces its inhibitory activity in vitro [4], therefore, sus- taining cellular Wnt signalling. A previously unasked question that we have sought to address in this study is whether mechanical load influences downstream responses mediated by canonical Wnt signalling in c-fos

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Optimal Performance of Mechanical Load Factor for the Solar Photovoltaic Electromechanical System

Optimal Performance of Mechanical Load Factor for the Solar Photovoltaic Electromechanical System

(14) Now, the current and voltage can be calculated from the Eqs. (14) and (10) to (12) for different DC motors. In all three cases, the voltage and current can be found independently of the PV modular characteristics. These are only calculated by the load and characteristics for each value of speed. And hence, it is possible to draw an I-V operating curve for the motor pump system. By drawing the operating curves of the motor on the PV module’s I-V curves. The motor whose operating curves follows closely. The locus of the module’s maximum power points at all irradiance levels provides the best adaptation to the module. The total daily electrical energy which can be delivered to the motor loads assuming that it is connected to the array during the entire period is then calculated from:

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Effect of mechanical load and polypeptide growth factors on cardiovascular fibroblast function

Effect of mechanical load and polypeptide growth factors on cardiovascular fibroblast function

Many tissues are exposed to mechanical forces and the concept of these forces regulating cell function is becoming established. The shear stress imposed by blood flow over the endothelium, the passive forces experienced by the lung during respiration, and the active tension generated by muscle cells all represent examples of the types of forces to which tissues are exposed. It is now clear that cells possess complex mechanosensory and mechanotransduction pathways that have yet to be elucidated, the consequences of which are to regulate important cellular events ranging from normal development, cellular morphology, tissue hypertrophy and pathological conditions. These mechanisms are complementary to the biochemical and neuronal signalling occurring in most tissues, previously thought to be entirely responsible for regulating cell behaviour. In many cases, as will become clear, the stimulus of mechanical load may be acting in concert with these other, more traditional, stimuli. Consequently, a disturbance of the normal mechanical environment of a cell population or tissue may lead to abnormal cellular behaviour and a rapid remodelling to accommodate the increased mechanical forces.

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Optimal Performance of Mechanical Load Factor for the Solar Photovoltaic Electromechanical System

Optimal Performance of Mechanical Load Factor for the Solar Photovoltaic Electromechanical System

different insolation levels to minimize the power drop, the load factors have the different values. In order to evaluate the effect of the load factor in the exponent of the torque-speed relationship is included. The load factor enables to obtain better utilization quality by the study of its effect on the power drop at all insolation levels and helps in selection and design of such photovoltaic system.

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Ratchet limits for a crack in a welded pipe subjected to a cyclic temperature load an a constant mechanical load

Ratchet limits for a crack in a welded pipe subjected to a cyclic temperature load an a constant mechanical load

In order to overcome the difficulties of the step-by-step elasto-plastic FEA, a number of direct methods based upon the Koiter's [5] kinematic and/or the Melan's [6] static theorems have been developed including: i) the nonlinear superposition method [7]; ii) mathematical programming methods [8-9]; iii) the Generalized Local Stress Strain (GLOSS) r-node method [10]; iv) the Elastic Compensation Method (ECM) [11, 12]; and v) the Linear Matching Method (LMM) [13-20]. The LMM is distinguished from other simplified methods by ensuring that equilibrium and compatibility are satisfied at each stage. The LMM has been shown to give accurate shakedown analysis to complex geometries and load histories [13, 14]. The LMM has also been extended to evaluate ratchet limits [15-18] for defect- free components subjected to cyclic load conditions from two- load extremes [15-17] to multi-load extremes [18]. However, the application of the latest LMM ratchet limit method [18] to structures with a discontinuity in the geometry and material has not yet been undertaken.

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A Discussion of Cracked Concrete Properties for Accidental Thermal Analysis

A Discussion of Cracked Concrete Properties for Accidental Thermal Analysis

At least three points are selected per concrete member. In other scenarios, more than 3 points may be appropriate for example for non-prismatic sections or where there are openings in the member. For this study, the points of maximum positive moment from the mechanical load case, of the maximum negative moment from the mechanical load case and of contra-flexure were chosen for the rigorous section analysis. Response of each reinforced concrete section was determined using the plane section hypothesis to compute the longitudinal strains at the chosen point for the mechanical load case, and the mechanical plus thermal load case. At each stage of loading, the strains were determined to satisfy force equilibrium and strain compatibility of the section. Once the strains at a cross section were determined, the stresses were then computed and the final moments in the sections were back calculated.

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Simulation and Analysis of Thermo Mechanical Coupling Load and Mechanical Dynamic Load for a Piston
Bhavani Shankar Kalluri & SK Hidayatulla Sharief

Simulation and Analysis of Thermo Mechanical Coupling Load and Mechanical Dynamic Load for a Piston Bhavani Shankar Kalluri & SK Hidayatulla Sharief

Ji Wu1,a, Shulin Duan1,b, Zhanhua Wu1,c, Hui Xing,d and Qin‟an Liu did a paper on The Coupled Thermal and Mechanical Load Analysis in the 6S50MC-C Type Marine Diesel' Piston. MAN Diesel‟s 6S50MC-C two-stroke marine diesel engine is researched in this paper. The intensity under the effect of thermal load, mechanical load and coupled loads are analyzed. As the boundary conditions of the temperature field distribution, the mean temperature and the mean heat transfer coefficient are calculated firstly. Based on the temperature field, the thermal intensity is obtained in ANSYS. Then the study analyzes the stress and the strain distribution when the mechanical load and the coupled loads are applied. Through the analysis of different loads, the maximum stress is 696MPa in thermal load, 191MPa in mechanical load and 659MPa in coupled loads. The maximum deformation is 1.011mm in thermal load, 0.147mm in mechanical and 1.022mm in coupled loads. The intensity meets the design requirement. The stress concentration and the deformation of the piston crown mainly are generated by the thermal load. To reduce the destructive effect of thermal, it requests enhancing cooling and warming up the main engine. Lokesh Singh, Suneer Singh Rawat, Taufeeque Hasan, Upendra Kumar's study is FINITE ELEMENT ANALYSIS OF PISTON IN ANSYS. A piston is a component of reciprocating engines.

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SECURE ROUTING IN MANET USING ASYMMETRIC GRAPHS

SECURE ROUTING IN MANET USING ASYMMETRIC GRAPHS

As a kind of thermal power machine, the working process of the engine is greatly related to heat transfer, as it decides various technical data of the engine such as the economical efficiency. And the increase of heat will cause the increase of the thermal load. As the main heated part of the engine, the piston has to bear the complicated mechanical load and thermal load subjected to periodical change. An analysis to the stress and the deformation condition under the mechanical load or the thermal load only is far from enough to reflect the actual working condition of the piston. A reference can only be provided for the piston design with factors influencing the thermal load found out, taking into overall consideration the piston intensity under the coupling effect of the thermal load and mechanical load.

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Nonlinear Vibration of Porous Funcationally Graded Cylindrical Panel Using Reddy’s High Order Shear Deformation

Nonlinear Vibration of Porous Funcationally Graded Cylindrical Panel Using Reddy’s High Order Shear Deformation

From the literature review, the authors often used the high order shear deformation theory to investigate the nonlinear static, nonlinear dynamic or nonlinear vibration of FGM or plate porous funcationally graded (PFG). For the nonlinear dynamic and vibration of PFGCP has not carried out. Therefore, in order to observe the nonlinear dynamic and vibration of PFGCP under mechanical load and thermal load, using the Reddy’s high order shear deformation theory and Ahry’ function are proposaled in this paper. The natural frequency of PFGCP is obtained by using cylindrical panel fourth- order Runge-Kutta method. Besides, the effect of geometrical ratio, elastic foundations: Winkler foundation and Paskternak foundation, the material properties and distribution type of porous on the modeling will be shown.

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The role of integrins in mechano-transduction leading to enhanced collagen synthesis in human cardiac fibroblasts

The role of integrins in mechano-transduction leading to enhanced collagen synthesis in human cardiac fibroblasts

In the cardiovascular system the mechanical environment is a key determinant of cellular activity. It regulates protein turnover, cell growth and cell division. Since mechanical forces continually change during development and under disease conditions, these forces play an important role in tissue remodelling during growth and disease. Collagen is a major protein component of the extracellular matrix of the heart and vasculature - it contributes to the functional integrity of the myocardium and blood vessel walls. Collagen is continually synthesised and degraded throughout life. Stimuli such as increased mechanical stress stimulate collagen turnover resulting in changes in the amount, distribution or types of collagen which may affect the cardiovascular function of the heart. The regulation of collagen synthesis by fibroblasts, the major collagen producing cells in the heart, is poorly understood. There is also little known as to how cells of the cardiovascular system detect changes in the mechanical environment - termed mechano-signal transduction - and how such signalling leads to changes in collagen synthesis and deposition. This thesis addresses the role of ECM composition in mechanical load induced procollagen synthesis and the importance of fibronectin integrins in mechano-signal transduction. Signalling pathways activated by mechanical load, and leading to procollagen synthesis are also examined.

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BMP2 and mechanical loading cooperatively regulate immediate early signalling events in the BMP pathway

BMP2 and mechanical loading cooperatively regulate immediate early signalling events in the BMP pathway

After 15 minutes of stimulation, mechanical loading led to the strong induction of p38, Akt and Erk1/2 phosphorylation (Figure 4). Erk1/2 and p38 have, in par- ticular, been described as important players during mechanotransduction in mesenchymal precursor cells [23,43,44]. Furthermore, signalling pathways via MAPK might be involved in regulating Smad signal intensity and duration. The Smad1 linker region comprises sev- eral sequential phosphorylation sites for cyclin depen- dent kinases (CDKs), MAPK and glycogen synthase kinase three beta (GSK3 b ) that regulate their transcrip- tional capacity and prime Smad molecules for degrada- tion via the ubiquitin proteasome pathway [9,45]. In contrast to the Smad pathway, we did not observe synergistic effects of mechanical load and BMP2 on the non-Smad target proteins. But gene regulation under loading conditions of osteogenic marker genes likely involves the interplay of Smad and non-Smad pathways.

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Analysis of spatial resolution in phase sensitive compression optical coherence elastography

Analysis of spatial resolution in phase sensitive compression optical coherence elastography

mixed into the silicone (refractive index = 1.4) in concentrations of 0.5 mg/ml in the bulk and 2.5 mg/ml in the inclusions [40]. The mechanical properties were controlled by selecting different elastomers and varying the ratio of the catalyst, curing agent, and silicone oil. The stress-strain relationship of each silicone was characterized using a custom-built uniaxial compression testing apparatus. The 2D plane-strain model used in the simulations effectively assumes that the sample is infinitely long in the out-of-plane (y) dimension [39] and to best match this assumption, the inclusions were made longer (10 mm long rectangular prisms) in the y-dimension, than in the x- and z-dimensions. The inclusions were cut using a custom made silicone slicing tool, to improve the accuracy of the cross-section geometry. Each phantom was made in four steps to ensure the inclusion was placed 600 μm from the top surface. Firstly, a base layer of silicone was poured into a glass petri dish, using real-time OCT in the x-z plane to aid in achieving the correct height, which, for each inclusion size, was determined as the total phantom height (3 mm) minus the sum of 600 μm and the inclusion height. Secondly, once the base had cured, the inclusion was placed on top. Thirdly, silicone was poured over the inclusion and base, guided by real-time OCT, to a height of 600 μm above the inclusion. Finally, once cured, the phantom was removed from the petri dish using a 15 mm diameter biopsy punch. Five different phantoms were made with varying inclusion size and mechanical contrast, as shown in Table 1.

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Evaluation Of Physical And Mechanical Properties Of Glass Fiber Reinforced Polyester Resin

Evaluation Of Physical And Mechanical Properties Of Glass Fiber Reinforced Polyester Resin

and isophthalic resin share a good Bonding capability and results in high specific strength, low density and high toughness. The resulting composites can used for application in car body rim, chassis and other parts resulting in reducing weight and overall increase in fuel efficiency. The effects of variation in fiber percentage on mechanical properties like Tensile strength, Bending strength and Impact load were investigated. With increase in glass fiber from 40% wt to 50% wt the maximum tensile load increased by 15%, tensile strength increased by 41.54% and the impact energy absorbed by 75%. On the other hand the bending load and bending strength increased by 26.35% and 25% with increase in Iso-Resin from 40% wt to 50% wt. Increase in glass fiber percentage has reversal effect on moisture absorption, ruling it out. In future research can be carried out in finding the additives like TiO 2 , CaCO 3 nano particles, granite powder to

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Modelling and analysis of a MEMS approach to dc voltage step up conversion

Modelling and analysis of a MEMS approach to dc voltage step up conversion

The micro-actuator then reduces the main capacitance thus performing the conversion. (ii) In the ‘active increase’ mode, the electrostatic actuator is used first to increase the main capacitance and at the same time to load the compliant mechanical suspension of the structure. The capacitor is charged and subsequent deactivation of the actuator prompts the mechanical suspension to reduce the main capacitance and thus increase the voltage. In this case, the actuator has to be controlled by a signal inverse to the one used in active reduction mode.

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Effects of load type (pollen or nectar) and load mass on hovering
metabolic rate and mechanical power output in the honey bee Apis
mellifera

Effects of load type (pollen or nectar) and load mass on hovering metabolic rate and mechanical power output in the honey bee Apis mellifera

by variation in hemolymph sugar levels. However, the Balderrama et al. (1993) and Moffat (2000) studies can be criticized because metabolic rates were averaged over periods including flight and non-flight (during which bees sat and fed on nectar). We address this controversy in two ways. First, we compare loading effects on metabolic rates in pollen and nectar foragers. We can directly compare our nectar-loading data to prior studies. In addition, because pollen foragers do not consume their load, there should be no confounding effects of variation in hemolymph sugar levels when comparing loaded and unloaded pollen foragers. Second, we examine the effect of load carriage on wing kinematics and calculated mechanical power output in hovering pollen foragers. In bumblebees, loading causes similar increments in metabolic rate and mechanical power output (Cooper, 1993); it seems reasonable that honey bees should show a similar pattern.

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Electrostatic sensor modeling for torque measurements

Electrostatic sensor modeling for torque measurements

As one can see in Fig. 9, the maximum induced charge oc- curs, when there is no torque load being applied to the beam. At that configuration the electret is closest to the plate. By increasing the load, the electret is being moved further away from the ideal conducting plate and one can observe a de- crease in the induced charge on the plate. The numerical anal- ysis of the measuring setup also shows, that it is only possi- ble to conclude the absolute value of the torque load from the

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