Region Of Wells Research Articles

Weakly Nonlinear Analysis of Flow-Driven Porous Anodic Oxide

Porous anodic oxide (PAO) films are formed by the electrochemical oxidation of metals such as titanium, aluminum, and other metals in acidic solutions. The optimal selection of parameters leads to the formation of submicron-sized pores arranged in a parallel hexagonal array within these films. Porous anodic oxide has enormous industrial applications in the development of functional nanodevices. The present study builds upon the flow-driven porous anodic oxide model proposed by Mishra and Hebert. They have shown through a linear stability analysis of the model that the inter-pore distance in PAO is successfully determined by the competition between stabilizing oxide formation and destabilizing viscous flow. In this work, we investigate the weakly nonlinear analysis of the model to determine the nature of instability arising in flow-driven porous anodic films beyond the stability threshold. For formation of well- developed pores, the nature of instability must be subcritical. However, the results of weakly nonlinear analysis show that the solutions resulting from neutral stability exhibit a supercritical nature for the practical range of anodizing control parameters as shown in Figure 1. Thus, in order to make accurate nonlinear predictions about the formation of pores, it is imperative to incorporate additional physics into the viscous flow model. We also determine the Hadamard stability criteria by tracking the neutral wavenumber to ascertain the regions of well- posedness of the viscous flow model. Figure 1

Cohort-based multiscale analysis of hemodynamic-driven growth and remodeling of the embryonic pharyngeal arch arteries.

Growth and remodeling of the primitive pharyngeal arch artery (PAA) network into the extracardiac great vessels is poorly understood but a major source of clinically serious malformations. Undisrupted blood flow is required for normal PAA development, yet specific relationships between hemodynamics and remodeling remain largely unknown. Meeting this challenge is hindered by the common reductionist analysis of morphology to single idealized models, where in fact structural morphology varies substantially. Quantitative technical tools that allow tracking of morphological and hemodynamic changes in a population-based setting are essential to advancing our understanding of morphogenesis. Here, we have developed a methodological pipeline from high-resolution nano-computed tomography imaging and live-imaging flow measurements to multiscale pulsatile computational models. We combine experimental-based computational models of multiple PAAs to quantify hemodynamic forces in the rapidly morphing Hamburger Hamilton (HH) stage HH18, HH24 and HH26 embryos. We identify local morphological variation along the PAAs and their association with specific hemodynamic changes. Population-level mechano-morphogenic variability analysis is a powerful strategy for identifying stage-specific regions of well and poorly tolerated morphological and/or hemodynamic variation that may protect or initiate cardiovascular malformations.

Desorption area and pressure-drop region of wells in a homogeneous coalbed

The coalbed methane (CBM) desorption area is highly important in the placement of wells to produce an adequate working system. This paper develops a homogeneous seepage model of CBM that incorporates desorption and uses a finite-element method to obtain the pressure field in complex boundary cases influenced by adjacent wells. The pressure field is presented in a 2D and pseudo-3D form that visually demonstrates the shape of the pressure profile and the pressure expansion. A method of combined numerical computation and contour drawing technology is used to determine the CBM desorption area and pressure drop region. By analyzing the main factors that affect the CBM desorption region, we demonstrate that a higher value of critical desorption pressure yields a larger desorption area of the seam. The effect of the permeability is different from the value of the critical desorption. This effect is determined by the critical desorption pressure level and the intersection of pressure profiles with different permeabilities. Permeability anisotropy leads to a desorption area with an elliptical shape. We also demonstrate that a greater flux of methane will result in a greater desorption region, and the effects of the distance between wells and the desorption area are closely related to the permeability. The developed model is applied in a field case to predict the desorption area.

Effectiveness of stirring measures in an axisymmetric rotating annulus flow

Lagrangian stirring in a thermally driven rotating annulus is investigated numerically using a Navier–Stokes model and a second order Runge–Kutta integration routine. The stirring properties are investigated using finite scale Lyapunov exponents, Lagrangian coherent structures and a leaking method. The ability of these measures to identify transport barriers, regions of well and poorly stirred flow, and stable and unstable manifolds is investigated, as well as the stirring properties of the annulus flow. It is found that finite scale Lyapunov exponents characterise the stirring properties of flows occurring in the rotating annulus more efficiently than the leaking method or Lagrangian coherent structures. The strength of the stirring varies monotonically with thermal forcing amplitude, but non-monotonically with forcing frequency. The flows investigated are axisymmetric (i.e. two dimensional) and time dependent.

Intercellular Junctions, Apical Differentiation, and Infiltrative Features in Colon Cancer: An Ultrastructural Study

Changes in the structure and number of cell junctions have been related to the infiltrative and metastatic potential of tumor cells. Apparently, the loss of cell adhesion should be coordinated with significant changes in the apical and basal cell domains. The authors have performed a sequential ultrastructural study of cells in the superficial, middle, and deep regions of well- and moderately differentiated colon adenocarcinomas. This was to investigate the differencesin the organization of different membrane domains among tumor cells in the in situ areas, the advancing, infiltrative edge of the tumors, and the infiltrating zones between these two extreme zones. The results of the study suggest that the organization of these domains is not strictly coordinated, and that, for each infiltration level, both a settling and an infiltrating cell population can be found. These findings could explain the fact that apparently well-differentiated tumors are able to seed distant tissues with individual cells, rather than with well-differentiated glandular aggregates that would hardly be able to reach the vessel lumina without significantly modifying their organization.

Effects of ZrO2 on the texturing and properties of melt-processed Y1Ba2Cu3O7−δ

The addition of ZrO2 is found to be very effective as the nucleation sites to promote the oriented growth of Y1Ba2Cu3O7−δ (YBCO) during peritectic solidification. Extended regions of well- textured YBCO grains with superior superconducting properties of the YBCO bulk are readily obtained by a single-step melt process at much lower process temperatures. At 77 K, the platelike Josephson weak-link behaviors observed in pure melt-processed YBCO have been effectively eliminated, indicating that the coherency between the spherulitic superconducting YBCO grains may have been greatly improved by ZrO2 additions.