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Porous Channel (porous + channel)

Distribution by Scientific Domains

Polymers and Materials Science	75%

Selected Abstracts

Simulations of flow through fluid/porous layers by a characteristic-based method on unstructured grids

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 11 2001
Baili Zhang
Abstract An upwind characteristic-based finite volume method on unstructured grids is employed for numerical simulation of incompressible laminar flow and forced convection heat transfer in 2D channels containing simultaneously fluid layers and fluid-saturated porous layers. Hydrodynamic and heat transfer results are reported for two configurations: the first one is a backward-facing step channel with a porous block inserted behind the step, and the second one is a partially porous channel with discrete heat sources on the bottom wall. The effects of Darcy numbers on heat transfer augmentation and pressure loss were investigated for low Reynolds laminar flows. The results demonstrate the accuracy and robustness of the numerical scheme proposed, and suggest that partially porous insertion in a channel can significantly improve heat transfer performance with affordable pressure loss. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Morphology and Crystalline Structure of Poly(, -Caprolactone) Nanofiber via Porous Aluminium Oxide Template

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 9 2006
Yang Chen
Abstract Summary: Poly(, -caprolactone) (PCL) nanofibers with a dimension of about 150 nm were successfully fabricated by using a process of extruding PCL solution via a porous aluminium oxide template and then solidifying in methanol. The morphology, melting behavior and crystalline structure of the nanofibers were investigated by using scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The results revealed that the weight-average molecular weight () of PCL hardly influenced the morphology of the nanofibers. However, the melting temperature (Tm) of the PCL crystalline increased slightly from 55.4 to 57.5,°C with an increase in . The accessional pressure and the presence of the porous template played an important role in the improvement of the orientation and crystallization structures of the polymer chains when they were passing through the nano-scale porous channel, leading to the conglomeration of the fiber and the much larger diameter than those from the pressure-induced extrusion process. Furthermore, comparing the processes with and without accessional pressure, the crystallinity of the nanofibers obtained under 0.2 MPa pressure increased, and the diffraction for the (001) lattice plane occurred. SEM image of PCL nanofibers extruded via a porous aluminium oxide template with the aid of pressure. [source]

Proton Transport from Dendritic Helical-Pore-Incorporated Polymersomes

ADVANCED FUNCTIONAL MATERIALS, Issue 18 2009
Anthony J. Kim
Abstract The ability to add synthetic channels to polymersome (polymer vesicle) membranes could lead to novel membrane composites with unique selectivity and permeability. Proton transport through two different synthetic pores, self-assembled from either a dendritic dipeptide, (6Nf-3,4-3,5)12G2-CH2 -Boc-L-Tyr-L-Ala-OMe, or a dendritic ester, (R)-4Bp-3,4-dm8G1-COOMe, incorporated into polymersome membranes are studied. Polymersomes provide an excellent platform for studying such transport processes due to their robustness and mechanical and chemical stability compared to liposomes. It is found that the incorporated dendritic dipeptide and dendritic ester assemble into stable helical pores in the poly(ethylene oxide)-polybutadiene (PEO-PBD) polymersomes but not in the poly(2-methyloxazoline)-poly(dimethylsiloxane)-poly(2-methyl oxazoline) (PMOX-PDMS-PMOX) polymersomes. The incorporation is confirmed by circular dichroism (CD), changes in purely synthetic mechanical strength (e.g., areal expansion modulus) as assessed by micropipette aspiration, and cryo-TEM. In addition to the structural analyses, a transport measurement shows the incorporated dendritic helical pores allow facile transport of protons across the polymersome membranes after up to one month of storage. This integration of synthetic porous channels with polymersome substrates could provide a valuable tool for studying active transport processes in a composite membrane. These composites will ultimately expand the family of biologically inspired porous-membrane mimics. [source]

Formation of microporous poly(hydroxybutyric acid) membranes for culture of osteoblast and fibroblast

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 12 2009
Han-Shiang Huag
Abstract Microporous membranes of a biodegradable polymer, poly(hydroxybutyric acid) (PHB), were prepared by a phase-inversion process and their cell compatibility was evaluated in vitro. A ternary system, ethanol/chloroform/PHB, was employed to prepare the membranes, wherein ethanol and chloroform were served as the nonsolvent and solvent for PHB, respectively. In the phase-inversion process, the polymer dissolution temperature was varied from 80 to 120°C to yield membranes with specific morphologies, such as globular particles, porous channels, etc. Moreover, cell viability was examined on the formed membranes. Two cell lines, osteoblast hFOB1.19 and fibroblast L929, were cultured in vitro. It was found that these two types of cells exhibited different responses on different membranes: the hFOB1.19 cells showed significant increase in cell proliferation with increase in surface roughness, whereas the L929 cells demonstrated an opposite trend, preferring to attach and grow on a flat surface. PHB membranes with different morphologies exhibit different cell compatibilities, which may be useful means for the architectural design of materials for tissue engineering. Copyright © 2009 John Wiley & Sons, Ltd. [source]