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Porous Walls (porous + wall)
Selected AbstractsFabrication of Microbeads with a Controllable Hollow Interior and Porous Wall Using a Capillary Fluidic DeviceADVANCED FUNCTIONAL MATERIALS, Issue 18 2009Sung-Wook Choi Abstract Poly(D,L -lactide-co-glycolide) (PLGA) microbeads with a hollow interior and porous wall are prepared using a simple fluidic device fabricated with PVC tubes, glass capillaries, and a needle. Using the fluidic device with three flow channels, uniform water-in-oil-in-water (W-O-W) emulsions with a single inner water droplet can be achieved with controllable dimensions by varying the flow rate of each phase. The resultant W-O-W emulsions evolve into PLGA microbeads with a hollow interior and porous wall after the organic solvent in the middle oil phase evaporates. Two approaches are employed for developing a porous structure in the wall: emulsion templating and fast solvent evaporation. For emulsion templating, a homogenized, water-in-oil (W/O) emulsion is introduced as the middle phase instead of the pure oil phase. Low-molecular-weight fluorescein isothiocyanate (FITC) and high-molecular-weight fluorescein isothiocyanate,dextran conjugate (FITC,DEX) is added to the inner water phase to elucidate both the pore size and their interconnectivity in the wall of the microbeads. From optical fluorescence microscopy and scanning electron microscopy images, it is confirmed that the emulsion-templated microbeads (W-W/O-W) have larger and better interconnected pores than the W-O-W microbeads. These microstructured microbeads can potentially be employed for cell encapsulation and tissue engineering, as well as protection of active agents. [source] Laser Writing: Direct Laser Writing of Photoresponsive Colloids for Microscale Patterning of 3D Porous Structures (Adv. Mater.ADVANCED MATERIALS, Issue 1 20091/2009) On pg. 66, Paul Braun and co-workers report the use of direct laser writing to pattern porous 3D structures from photo-responsive colloidal building blocks. Upon 2-photon exposure, the colloids become highly attractive, enabling localized control of aggregation behavior. 3D structures composed of porous walls are harvested by writing into a colloidal sediment of these particles, followed by rinsing away unexposed colloidal species. Applications may include microfluidics, and studies of porous media, cellular growth and signaling, and colloidal physics. Cover art by Steven Eisenmann of the Beckman Institute VMIL. [source] Direct Laser Writing of Photoresponsive Colloids for Microscale Patterning of 3D Porous Structures,ADVANCED MATERIALS, Issue 1 2009Matthew C. George 3D patterning of colloidal structures is enabled by the phototriggered aggregation of photoresponsive colloids. We use direct laser writing to locally control aggregation behavior of photoresponsive colloids via a 2-photon absorption process. 3D structures composed of porous walls are harvested after rinsing away unexposed colloidal species. Aggregation is fully reversible with sufficient agitation. [source] Analysis of velocity equation of steady flow of a viscous incompressible fluid in channel with porous wallsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 9 2010M. Babaelahi Abstract Steady flow of a viscous incompressible fluid in a channel, driven by suction or injection of the fluid through the channel walls, is investigated. The velocity equation of this problem is reduced to nonlinear ordinary differential equation with two boundary conditions by appropriate transformation and convert the two-point boundary-value problem for the similarity function into an initial-value problem in which the position of the upper channel. Then obtained differential equation is solved analytically using differential transformation method and compare with He's variational iteration method and numerical solution. These methods can be easily extended to other linear and nonlinear equations and so can be found widely applicable in engineering and sciences. Copyright © 2009 John Wiley & Sons, Ltd. [source] Evidence for the importance of odour-perception in the parasitoid Rhopalicus tutela (Walker) (Hym., Pteromalidae)JOURNAL OF APPLIED ENTOMOLOGY, Issue 6 2001E. M. Pettersson Possible host location mechanisms in the chalcid wasp Rhopalicus tutela (Walker) (Hym., Pteromalidae), a parasitoid of the eight-spined spruce bark beetle, Ips typographus (L.) (Col., Scolytidae), were examined. This was carried out in order to repeat and complement former studies on parallel parasitoid,scolytid systems that had contradictory results. Morphological examinations of the parasitoid antennae were made using both scanning and transmission electron microscopy. Possible functions of the sensilla placodea (multiporous plate sensillum), and other sensilla present on the antennae, have been indicated. For the first time, the placoid sensilla in a pteromalid parasitoid have shown porous walls and numerous innervations, which are typical characteristics for chemoreceptors. Previously the placoid sensilla have been suggested to be an infrared receptor. In order to test the chemoreceptive ability of R. tutela females and males, a synthetic reference blend was analysed by combined gas chromatography and electroantennographic detector (GC-EAD). Their sensitivity to host-related volatiles (such as certain pheromone components and oxygenated monoterpenes) was significantly greater than that for host-tree-related compounds (monoterpene hydrocarbons). Employing an infrared thermo-scanner, the current study failed to detect ,hot spots' associated with susceptible hosts beneath the bark. Results from electrophysiology and electron microscopy revealed clear odour-perceptive functions of the parasitoid antennae. These results strongly support the major importance of volatiles in host location by the bark beetle parasitoid R. tutela. [source] Reforming diesel-fuel distillates with membrane reactorsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010Michael V. Mundschau Abstract A porous-membrane reactor is used to produce H2 and CO by dry partial oxidation of volatile hydrocarbons distilled from diesel fuel. To eliminate deposition of thermodynamically and kinetically favored carbon onto reactor walls as the fuel is heated, cool air is brought into reactors through porous walls of refractory, zirconia-based ceramic. Flow of air through reactor walls suppresses alkyl-radical polymerization that otherwise leads to formation of tar and soot in the reformer heating zone. Diesel fuel is distilled just below 200 °C to avoid cracking of long-chain n -alkanes. The volatile distillates enter the reformer in the vapor phase, eliminating need for complex liquid-fuel injectors and mixers. Volatile distillates are relatively easily reformed, eliminating soot and most naphthalene in the exhaust, converting 88 mole% of carbon in the distillate into CO, 7% into CH4, and 5% into CO2. Approximately 75 mole% of the hydrogen is converted into H2, 13% into CH4, and the remainder into H2O. Synthesis gas produced from diesel fuel distillates could fuel solid-oxide fuel cells or regenerate NOx traps used in pollution control. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | ||||||||||