An element free Galerkin (EFG) method is proposed to analyze the natural frequencies of composite laminates of complicated shape. The present method uses moving least squares (MLS) approximation to ...construct shape functions based on a set of nodes scattered in the problem domain. The dynamic equations of the system are formulated using the Lagrangian equation. The essential boundary conditions are imposed using their weak forms with Lagrange multipliers. Orthogonal transformation technique is used to implement the essential boundary conditions in the eigenvalue equation. The present EFG method is coded in Fortran. Numerical examples are presented for plates of square, elliptical and complicated shapes with different boundary conditions.
This paper presents a rapid and reliable approach to solve inverse problems of parameter estimation for structural systems using reduced-basis method (RBM). A reduced-basis model is first developed ...with asymptotic error estimation and is used for fast computation of solving forward mechanics problems of solids and structures. A genetic algorithm (GA) is then used in the inverse search procedure for parameter estimation. The approach is applied to a typical inverse problem of estimating the crack location, length and orientation inside a cantilever beam. The displacements measured at five points on the lower surface of the beam which can also be evaluated by our fast RBM solver are used as inputs for constructing objective functions of error. The genetic algorithm is used to search these parameters of the crack inside cantilever beam that minimize the objective function. An example has been presented. It is found that the estimated results are very accurate and reliable due to the use of RBM forward model with an effective and robust error estimation and detailed sensitivity analysis. The present procedure is 460 times faster than the full FEM model used inverse procedure.
Macrophages are major targets for infection by human immunodeficiency virus type 1 (HIV‐1). In addition to their role as productive viral reservoirs, inappropriate activation of infected and ...uninfected macrophages appears to contribute to pathogenesis. HIV‐1 infection requires initial interactions between the viral envelope surface glycoprotein gp120, the cell‐surface protein CD4, and a chemokine receptor CCR5 or CXCR4. Besides their role in HIV‐1 entry, CCR5 and CXCR4 are G protein‐coupled receptors that can activate multiple intracellular signaling pathways. HIV‐1 gp120 has been shown to activate signaling pathways through the chemokine receptors in several cell types including lymphocytes, neurons, and astrocytes. In some cell types, these consequences may cause cellular injury. In this review, we highlight our data demonstrating diverse signaling events that occur in primary human macrophages in response to gp120/chemokine receptor interactions. These responses include K+, Cl–, and nonselective cation currents, intracellular Ca2+ increases, and activation of several kinases including the focal adhesion‐related tyrosine kinase Pyk2, mitogen‐activated protein kinases (MAPK), and phosphoinositol‐3 kinase. Activation of the MAPK leads to gp120‐induced expression of chemokines such as monocyte chemoattractant protein‐1 and macrophage‐inflammatory protein‐1β and the proinflammatory cytokine tumor necrosis factor α. These responses establish a complex cytokine network, which may enhance or suppress HIV‐1 replication. In addition, dysregulation of macrophage function by gp120/chemokine receptor signaling may contribute to local inflammation and injury and further recruit additional inflammatory and/or target cells. Targeting these cellular signaling pathways may have benefit in controlling inflammatory sequelae of HIV infection such as in neurological disease.
Background: Insulin-like growth factor-I (IGF-I) has been shown to protect against stroke in rats when administered intracerebroventricularly. However, this invasive method of administration is not ...practical for the large number of individuals who require treatment for stroke. Intranasal (IN) delivery offers a noninvasive method of bypassing the blood–brain barrier (BBB) to deliver IGF-I and other neurotrophic factors to the brain. Here, we demonstrate for the first time the therapeutic benefit of IN IGF-1 in rats following middle cerebral artery occlusion (MCAO).
Methods: A blinded, vehicle-controlled study of IN IGF-I was performed using the intraluminal suture occlusion model. Rats were randomly divided into vehicle-control, 37.5 and 150 μg IGF-I-treated groups. Treatments occurred at 10 min after onset of 2 h of MCAO, and then 24 and 48 h later. Four neurologic behavioral tests were performed 4, 24, 48 and 72 h after the onset of MCAO. Corrected infarct volumes were evaluated 72 h after the onset of MCAO.
Results: Treatment with the 150 μg IGF-I significantly reduced the infarct volume by 63% vs. control (
p=0.004), and improved all the neurologic deficit tests of motor, sensory, reflex and vestibulomotor functions (
p<0.01). However, the 37.5-μg dose of IGF-I was ineffective.
Conclusion: While IGF-I does not cross the BBB efficiently, it can be delivered to the brain directly from the nasal cavity following IN administration, bypassing the BBB. IN IGF-I markedly reduced infarct volume and improved neurologic function following focal cerebral ischemia. This noninvasive, simple and cost-effective method is a potential treatment for stroke.
The sealing failure of cement sheath which caused annulus pressure in shale gas wells have significantly affected the safe and efficient development of shale gas. In view of the integrity of cement ...sheath which is affected by the high fluid pressure in casing during the hydraulic fracturing treatment, an experimental device for testing the integrity of cement sheath is established. In addition, the analytical model for calculating the stress and strain of the well system is established based on parameters of the experimental device. The analytical model for calculating the circumferential strain at outer wall of the steel cylinder is achieved. The error of stress-strain between analytical calculated results and the experimental results is very small. In sensitivity analysis, the parameters which affect the stress on cement sheath interface is discussed. This study has a certain reference value for the design of experiment device and the analysis of sealing ability of cement sheath in shale gas wells.
The dynamics (rotation and stabilization) of single irregular particles that are constrained to rotate only and until to a quasi-steady state in a two-dimensional channel with viscous flow is ...numerically investigated using the gradient smoothed method (GSM). The GSM is proved to be computationally stable for arbitrary, irregular geometries discretized with distorted grids and well agreements with others' work are revealed in validation cases. This work focuses on the influences of irregular particles' typical shapes, including ellipse, rectangle and triangle, on the relevant surface forces, the flow dynamics, and the response time of the rotation. The effects of aspect ratio and flow velocity are studied in detail for all three typical types of irregular particles. It is found that the imbalance of the total torque on the surface of the particle causes the rotation, and when the particle is approaching the final stable position, the total torque becomes nearly zero with a small fluctuation, which contributes a local oscillation around the stable direction. In our cases, under the constraints, it is found also that the broad side of the elliptical particle always tends to be along the stream. For the rectangular particle, however, the aspect ratio and the flow velocity collectively determine the final orientation which means the major side or the diagonal line is along the flow stream. In addition, the triangular particle is found to behave quite differently in terms of both rotation and stabilization. The 'response time' of three types of particles is finally obtained from our GSM simulations. These findings could be helpful for a better understanding on the fluid-particle interactions and maybe advisory for determining the shape factor which is a key parameter for multiple particles motions.
Panguite (IMA 2010-057), (Ti4+,Sc,Al,Mg,Zr,Ca)1.8O3, is a new titania, occurring as fine-grained crystals with Ti-rich davisite in an ultra-refractory inclusion within an amoeboid olivine inclusion ...from the Allende CV3 carbonaceous chondrite. The phase was characterized by SEM, EBSD, synchrotron micro-diffraction, micro-Raman spectroscopy, and EPMA. The mean chemical composition of the type panguite is (wt%) TiO2 47.97, ZrO2 14.61, Sc2O3 10.67, Al2O3 7.58, MgO 5.54, Y2O3 5.38, CaO 3.34, SiO2 1.89, FeO 1.81, V2O3 0.95, Cr2O3 0.54, HfO2 0.28, sum 100.56 with a corresponding empirical formula calculated on the basis of 3 O atoms of (Ti0.79Zr0.16Si0.04)4+Σ0.99 (Sc0.20Al0.20Y0.06V0.02Cr0.01)3+Σ0.49 (Mg0.18Ca0.08Fe0.03)2+Σ0.29Σ1.77O3. Synchrotron micro-Laue diffraction (i.e., an energy scan by a high-flux X-ray monochromatic beam and white beam diffraction) on one type domain at sub-micrometer resolution revealed that panguite is an orthorhombic mineral in space group PBCA: The structure is a subgroup of the Ia3 bixbyite-type. The cell parameters are a=9.781(1), b=9.778(2), and c=9.815(1) Å, yielding V=938.7(1) Å3, Z=16, and a calculated density of 3.746 g/cm3. Panguite is not only a new mineral, but also a new titania material, likely formed by condensation. It is one of the oldest minerals in the solar system.
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