Elucidation of Longitudinally Grooved-Riblets Drag Reduction Performance using Pressure Drop Measurements

The need to determine affordable and environmentally friendly methods of reducing skin friction can be identified as one of the reasons contributing towards the study of the effectiveness of riblet shapes. Water tank experiments were carried out to optimize the shape and dimensions of microstructure grooves over a flat plate. The use of organized microstructures on channel walls is proposed to obtain lower values of pressure losses on smooth walls. Three shapes of microstructure grooves were investigated, with same groove height (600 μm) and five spacing dimensions (600, 750, 1000, 1500 μm), in water flows with velocities of up to 0.4 m/s. This was done for all selected types of riblet, which are fixed with the direction aligned with the flow. The experimental results showed that the size and shape of the riblets can massively incubate some of the turbulent structures formed on the surface and that will lead to a more controllable flow environment, which can result in drag reduction

Oil-soluble organic polymer driven from aloe vera as drag reducing agent for crude oil flow in pipelines

In the present work, an organic oil-soluble drag-reducing agent (DRA) is introduced and experimentally tested. The new additive is driven from aloe vera mucilage extracted directly from the aloe vera plant. Polymer grafting process was implemented to change the solubility of the new additives from water-soluble to oil-soluble. Drag reduction solutions are prepared by mixing certain additives concentrations (200 wppm to 600 wppm) with the crude oil. Each solution was rheologically tested to examine the effect of the additives on the viscosity and viscoelastic properties of the crude oil. The drag reduction performance was examined using a closed-loop liquid circulation system specially designed and fabricated for the present work. The experimental results showed that the viscosity of the solutions decreases when the concentration of the additives increases without affecting the crude oil entity (Newtonian behaviour) with noticeable dramatic changes in the viscoelastic properties. A maximum drag reduction percentage of 82% was achieved with an additive concentration of 600 wppm. Finally, the resistance of the new additives to mechanical shear forces was high and increased exponentially with the concentration

Opportunistic infections in immunosuppressed patients with juvenile idiopathic arthritis: Analysis by the Pharmachild Safety Adjudication Committee

Background: To derive a list of opportunistic infections (OI) through the analysis of the juvenile idiopathic arthritis (JIA) patients in the Pharmachild registry by an independent Safety Adjudication Committee (SAC). Methods: The SAC (3 pediatric rheumatologists and 2 pediatric infectious disease specialists) elaborated and approved by consensus a provisional list of OI for use in JIA. Through a 5 step-procedure, all the severe and serious infections, classified as per MedDRA dictionary and retrieved in the Pharmachild registry, were evaluated by the SAC by answering six questions and adjudicated with the agreement of 3/5 specialists. A final evidence-based list of OI resulted by matching the adjudicated infections with the provisional list of OI. Results: A total of 772 infectious events in 572 eligible patients, of which 335 serious/severe/very severe non-OI and 437 OI (any intensity/severity), according to the provisional list, were retrieved. Six hundred eighty-two of 772 (88.3%) were adjudicated as infections, of them 603/682 (88.4%) as common and 119/682 (17.4%) as OI by the SAC. Matching these 119 opportunistic events with the provisional list, 106 were confirmed by the SAC as OI, and among them infections by herpes viruses were the most frequent (68%), followed by tuberculosis (27.4%). The remaining events were divided in the groups of non-OI and possible/patient and/or pathogen-related OI. Conclusions: We found a significant number of OI in JIA patients on immunosuppressive therapy. The proposed list of OI, created by consensus and validated in the Pharmachild cohort, could facilitate comparison among future pharmacovigilance studies. Trial registration: Clinicaltrials.gov NCT 01399281; ENCePP seal: awarded on 25 November 2011

Energy Dissipation Reduction Using Similarly-Charged Polymer-Surfactant Complex

Transporting viscous liquids in pipelines is considered as one of the most energy consuming sectors in the industry due to the turbulent flow mode associated. High molecular weight polymers are effective drag reduction agents for enhancing liquid flow through pipelines, but they typically break apart (mechanical degradation) when subjected to high shear forces. Introducing a surfactant to the polymer to form a polymer-surfactant complex is a known technique to minimize the mechanical degradation. However, most available polymer-surfactant complexes formed of oppositely charged additives tend to exhibit low drag reduction performance. In the present study, we chose a different approach by investigating the drag reduction performance and mechanical degradation resistance of a similarly charged polymersurfactant complex using a rotating disk apparatus (RDA). Additionally, transmission electron microscopy (TEM) was used to gain an in-depth perspective into the polymer-surfactant complex structure. The experimental results showed that rigid complexes are successfully formed and exhibit improved drag reduction performance and mechanical degradation resistance. © 2015 Pushpa Publishing House, Allahabad, India

Electrochemical Disposition of Titanium Dioxide Photocatalyst on Micropores Silicon Wafer for Water Treatment Application

Titanium dioxide (TiO2), due to wide band gap, has a limited use in water treatment process because of its low activity under visible light. Such drawback is usually associated with the inadequate solar spectrum that activates its surface, i.e., most of the photoexcited electron-hole pairs tend to recombine, leading to a reduction in the photocatalytic performance. Immobilization of TiO2 on the surface of silicon is considered as a useful approach to overcome this drawback. However, the immobilization methods require high temperature and pressure, which limit the numbers and types of materials that can be utilized as a substrate. The known electrochemical deposition procedures are usually conducted through two major steps, electrochemical oxidation and hydrolysis of Ti(III) precursor to form a thin layer on the surface of the substrate, followed by thermal annealing to form crystalline phase. The present work introduces the immobilization of titanium dioxide on a microporous silicon (MPSi) wafer through direct electrochemical deposition, where titanium dioxide P25 was used in the electrolyte solution. The photocatalyst surface morphology and composition were characterized using Scan Electron Microscope (SEM), Electron Dispersive X-ray (EDX), X-ray diffraction (XRD), and X-ray Photoemission Spectroscopy (XPS) techniques. The photocatalytic activities of the new composites were investigated, and the experimental results indicate that the fabricated TiO2–MPSi showed higher methylene blue degradation rate than that of the conventional P25 catalyst. This is due to the unique photosensitivity and porous structure of the new photocatalytic composites. with the advantages of using this method, it is believed that more efficient photocatalyst can be produced

In situ ultrasound enhancement of octanoic acid directional solvent extraction for seawater desalination

The low yield and high salinity of the water product have limited the use of directional solvent extraction desalination method to the treatment of only low salinity water. In this research, in situ ultrasound enhancement of octanoic acid solvent extraction desalination is reported. The pre-prepared 3.5% (w/w) of saltwater solution and octanoic acid were mixed at five different temperatures which resulted in two phases. The performance of extraction for each set was evaluated based on salinity, yield of the recovered water, and solvent residual in the product water. The calculated yield of pure water under the ultrasound effects was higher than that without the ultrasound. This is due to the role of ultrasound in weakening the intermolecular interaction to dissociate water from salt, increasing the solvent efficiency in extracting water. The recovered water salinity was lower by using the ultrasound which can be explained as result of increasing the water yield

Enhanced titanium dioxide photocatalyst embolized on micropores silicon wafer: An experimental approach

BACKGROUND: The wide bandgap and low activity under visible light of titanium dioxide (TiO2) have limited its use in many industrial processes. This limitation is associated with the inadequate solar spectrum that activates its surface, where most of the photoexcited electron–hole pairs recombine thus, leading to a drop in the photocatalytic performance. Immobilization of TiO2 on the surface of other materials such as silicon is a suitable approach to overcome these drawbacks. However, the known immobilization methods require either high‐temperature or high‐pressure conditions. The objective of the present work is to introduce and evaluate a low power‐consumption electrodeposition method for creating a new photocatalyst that can act in visible light using electrochemical anodization for immobilizing the TiO2 on a silicon wafer surface. Two methods were utilized for immobilization which is electrodeposition and sol–gel. The prepared photocatalyst surface and composition were characterized by scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDX), X‐ray diffraction (XRD), and X‐ray photoelectron spectroscopy (XPS)

Biopolymer-surfactant complexes as flow enhancers : characterization and performance evaluation

Artificial polymeric additives are known, and experimentally proven, to be effective drag reducing agents in pipelines with turbulent flow medium. The artificial nature of these additives and their low resistance to high shear forces, exerted by the pipeline geometries and equipment, are considered as major problems against a wider implementation in other industrial applications. The present work introduces a new polymer-surfactant complex of two organic additives (chitosan and sodium laurel ether sulfate, SLES) as a drag reducing agent. The rheological and morphological properties of the new complexes were experimentally tested. The new complex’s drag reduction performance and stability against high shear forces were analyzed using rotating disk apparatus. All the investigated solutions and complexes showed a non-Newtonian behavior. The cryo-TEM images showed a unique polymer-surfactant macrocomplex structure with a nonlinear relationship between its rheological properties and surfactant concentration. A maximum flow enhancement of 47.75% was obtained by the complex (chitosan 300 and 400ppmof chitosan and SLES, respectively) at the rotation speed of 3000 rpm. Finally, the stability of the proposed additives was highly modified when the additive complexes were formed

Rapid Prototyping of Microfluidics Devices using Xurograhy Method

Rapid prototyping of microchannel gain lots of attention from researchers along with the rapid development of microfluidic technology. The conventional methods carried few disadvantages such as high cost, time consuming, required high operating pressure and temperature and involve expertise in operating the equipment. In this work, new method adapting xurography method is introduced to replace the conventional method of fabrication of microchannels. The novelty in this study is replacing the adhesion film with clear plastic film which was used to cut the design of the microchannel as the material is more suitable for fabricating more complex microchannel design. The microchannel was then mold using polymethyldisiloxane (PDMS) and bonded with a clean glass to produce a close microchannel. The microchannel produced had a clean edge indicating good master mold was produced using the cutting plotter and the bonding between the PDMS and glass was good where no leakage was observed. The materials used in this method is cheap and the total time consumed is less than 5 hours where this method is suitable for rapid prototyping of microchannel