Biodegradable microfabricated plug-filters for glaucoma drainage devices

We report on the development of a batch fabricated biodegradable truncated-cone-shaped plug filter to overcome the postoperative hypotony in nonvalved glaucoma drainage devices. Plug filters are composed of biodegradable polymers that disappear once wound healing and bleb formation has progressed past the stage where hypotony from overfiltration may cause complications in the human eye. The biodegradable nature of device eliminates the risks associated with permanent valves that may become blocked or influence the aqueous fluid flow rate in the long term. The plug-filter geometry simplifies its integration with commercial shunts. Aqueous humor outflow regulation is achieved by controlling the diameter of a laser-drilled through-hole. The batch compatible fabrication involves a modified SU-8 molding to achieve truncated-cone-shaped pillars, polydimethylsiloxane micromolding, and hot embossing of biodegradable polymers. The developed plug filter is 500?μm long with base and apex plane diameters of 500 and 300?μm, respectively, and incorporates a laser-drilled through-hole with 44-μm effective diameter in the center.     

Conjugate heat transfer of laminar mixed convection of a nanofluid through an inclined tube with circumferentially non-uniform heating

Laminar mixed convection of a nanofluid consisting of water and Al₂O₃ in an inclined tube with heating at the top half surface of a copper tube has been studied numerically. The bottom half of the tube wall is assumed to be adiabatic (presenting a tube of a solar collector). Heat conduction mechanism through the tube wall is considered. Three-dimensional governing equations with using two-phase mixture model have been solved to investigate hydrodynamic and thermal behaviours of the nanofluid over wide range of nanoparticle volume fractions. For a given nanoparticle mean diameter the effects of nanoparticle volume fractions on the hydrodynamics and thermal parameters are presented and discussed at different Richardson numbers and different tube inclinations. Significant augmentation on the heat transfer coefficient as well as on the wall shear stress is seen.     

The Investigation of Vertical Wells' Optimum Two-phase Flow Empirical Correlation for the Ab-Teymour Reservoir

Abstract

There are different procedures for predicting pressure drop in two-phase flow pipelines. However, for each reservoir one or two correlations or mechanistic models give more accurate results. The authors investigated various correlations and mechanistic models in order to match fluid pressure losses considering all parameters such as friction, liquid holdup, superficial velocities, densities, viscosities, and interfacial tension. Commercial software, Pipesim, was used to simulate the fluid pressure losses. Drift flux modeling for predicting pressure profile was also investigated. A program for calculating pressure drops and average deviation of calculated pressures using this drift flux model was developed and the results were compared with other correlations.     

Adsorptive separation of La(III) from aqueous solution via the synthesized [Zn(bim)2(bdc)]n metal-organic framework

Lanthanum is one of the rare earth metals which due to specific chemio-physical properties, has wide applications in different industries. In this research, the ability of the synthesized metal-organic framework (MOF), [Zn(bim)₂(bdc)]_n (ZBB) for the removal of lanthanum ions from the aqueous stream was investigated in the batch and column processes. The synthesized MOF was characterized by using scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The effect of pH on lanthanum ions adsorption was evaluated in the range from 1 to 7. Moreover, isothermal, kinetic, and thermodynamic parameters for adsorption of La(III) ions onto the synthesized MOF were evaluated. The adsorption capacity of lanthanum ions onto the synthesized MOF was calculated to be about 130 mg/g. Thermodynamic studies demonstrate the endothermic and chemical nature of lanthanum adsorption, while kinetic studies suggest the pseudo-first-order of reaction. In column mode, the effect of solution flow rate passing through the fixed-bed was studied. Experimental data confirm that increasing the bed flow rate causes a decrease in the adsorption capacity of lanthanum ions on the synthesized MOF.     

CO2 reforming of methane over Ni-Cu/Al2O3-ZrO2 nanocatalyst : The influence of plasma treatment and process conditions on catalytic properties and performance

Argon glow discharge plasma was applied for treatment of impregnated Ni-Cu/Al₂O₃-ZrO₂ nanocatalyst. The catalytic performance toward CO₂ reforming of methane and the physicochemical properties were investigated by means of GC, BET, XRD, FESEM, TEM, EDX, TG-DTG, XPS and FTIR techniques. The plasma-treated nanocatalyst contains smaller crystal size and high dispersion of NiO. Plasma treatment decreased particle size and plasma high energy species flattened particles on support, increasing the interaction between support and active metals which leads to high catalytic activity. Low temperature activity and H₂/CO ratio closer to 1 was observed for plasma-treated nanocatalyst compared to non-treated sample. Moreover, higher product yield and H₂/CO ratio was found in CH₄/CO₂=1 rather than CH₄/CO₂=1.5. Time on stream test during 1,440 min at 850 °C showed plasma-treated Ni-Cu/Al₂O₃-ZrO₂ nanocatalyst did not experience any deactivation in terms of CH₄ and CO₂ conversion and H₂/CO ratio.     

Synthesis and characterization of maleylated cellulose-<Emphasis Type="Italic">g</Emphasis>-polyacrylamide hydrogel using TiO<Subscript>2</Subscript> nanoparticles under sunlight

Graft polymerization onto the cellulose is one way to produce semisynthetic copolymers and semiconductors were hardly used as initiators. Maleylated cellulose (MC) with different degree of carboxyl groups was synthesized and degree of carboxyl groups was determined using titration method. Then the graft copolymers of acrylamide (AM) on MC were synthesized by titanium dioxide semiconductor photoinitiator in aqueous suspension under sunlight. The effect of different parameters, such as the degree of carboxyl groups, degassing of atmosphere, reactor type, light source, MC/AM ratio, and initiator concentration, was evaluated in the synthesis of graft copolymers. MC with a high degree of carboxyl groups about 2.8 mmol g^?1 was selected for graft photopolymerization. Maximum monomer conversion (55%) for Maleylated cellulose-g-polyacrylamide (MC-g-PAM) was achieved with 0.5 mg TiO₂, MC/AM = 0.056, argon atmosphere, sunlight source, and double quartz tube reactor. The maximum amount of equilibrium swelling (41 g g^?1) was achieved for MC-g-PAM with 34% monomer conversion. The resulting graft copolymers were characterized by FT-IR, SEM, and TGA. Synthesis of MC-g-PAM using TiO₂ nanoparticles (NPs) as the initiator was done successfully that shows the TiO₂ NPs are useable in graft polymerization of acrylamide monomers onto the MC under sunlight.