Papers by Keyword: Electro-Osmosis

Abstract: This study presents the possibility of control of nanofluidics in the bio-inspired nanosized ion channel using a field effect transistor (FET) structure. We analyzed effects from main dominant factors to control the ion flow in nanosized channel such as electro-osmosis, diffusion effect, Coulomb force between ions and pressure force. Additionally, we suggest a strategy to control the ion flow accurately at the specific position in the nanochannel by handling the viscosity, ion molecular density, pressure, gate and trans-cis voltages of FET structure.

Abstract: Simulated electric field distribution in concrete by using of ANSYS finite element analysis software, researched influences of some factors on electric field strength and electric potential in concrete. Which include resistivity of cement soil and its electric field strength are inversely proportional and the electric potential distribution is less affected by resistivity changes, applied voltage is proportional to electric field strength and potential, the more the number of cathode induces the greater and uniform of the strength, electric field distribution within cement soil becomes sparse and its values are relatively smaller with the anode spacing increasing, electric field strength of cement-soil is more intensive and its distribution is more uniform and also its values is relatively larger with the decreasing of cathode spacing.

Abstract: This paper verified effect and feasibility by indoor model test of using drainage of vacuum preloading method and electro-osmosis method to reduce water content of saturated over-wet soil in moist and rainy areas. The results showed that: both methods could effectively reduce water content of saturated over-wet soil in Ya’an area, to achieve the desired effect of drainage and consolidation. Neither spatial distribution of level of reducing water content was obvious.

Abstract: Based on laboratory model test, this paper presents the draining efficiency of vacuum pre-loading method and electro-osmosis method with over-wet soil in moist and rainy areas. The results show that: both methods can effectively reduce the water content of saturated over-wet soil in Ya’an area, to achieve the desired effect of drainage and consolidation; and the degree of the effects of both methods differ with spatial variation.

Abstract: Dysfunction of the corneal endothelium due to cell loss caused by aging, disease or trauma can lead to severe visual impairment and blindness. Traditionally, dysfunctional endothelia are managed surgically, by removing the entire central cornea and transplanting either donor corneal tissue (penetrating keratoplasty), or just endothelia isolated from donor corneas. As in many cases it is only the corneal endothelium requiring replacement, many attempts were made over the last decades to develop an endothelial substitute, thereby precluding the need for the use of full donor corneas. This article reviews these attempts, which include artificial membranes, cell-coated corneal transplants, and cell-coated membranes. The presumption of an artificial corneal endothelium capable of duplicating the transendothelial ion-and-fluid transport function is examined in light of the latest hypotheses regarding the mechanism of this function.

Abstract: In below-grade buildings and buried structures, such as those constructed as hardened secure facilities and used for munitions storage on U.S. Army installations, water intrusion can cause serious damage and reduce penetration resistance. Inside the building active water and high humidity can result in corrosion of HVAC, electronic equipment, as well as damage or disrupt mission critical electronic equipment. In the adjacent backfill and the structure itself, excessive water can seriously compromise the structural hardening of the facility. Thus, it is vital to Army sustainability to control moisture in below-grade structures and eliminate corrosion of electrical mechanical equipment. This also prevents mold growth on the interior surface of below grade concrete walls and floors. Control of water movement involves both actively removing water in and around a building, and the use of barriers to prevent water from penetrating to interior spaces. A pumping system is typically required with the use of a barrier system to assist in controlling the movement of moisture into the structure. Conventional waterproofing technologies are expensive and often have short service life. A new approach is needed—a cost effective and robust solution—to the pervasive problem of water intrusion. Electro-Osmotic Pulse is a promising alternative solution presented here. Electro-Osmotic Pulse (EOP) technology uses pulses of electricity to reverse the flow of water seepage. The applied voltage causes moisture to flow out of the basement walls and away from the building. The technology works by alternately pulsating a direct electric field with an off period. The first part of the sequence consists of a pulse of positive voltage (as seen from the dry side of the concrete wall), followed by a pulse of negative voltage. This is followed by a period when no voltage is applied. Of the three parts, the positive voltage pulse has the greatest time duration. The amplitude of the positive signal is typically on the order of 20 to 40 Volts DC. This electrical pulse causes cations (e.g., Ca++) and associated water molecules to move from the dry side (anode) towards the wet side (cathode) against the direction of flow induced by the hydraulic gradient, thus preventing water penetration through buried concrete structures. Laboratory and field tests have shown an increase in calcium compounds at the cathode side of test specimens. The negative portion of the pulse increases the efficiency of moisture movement by depolarizing the electrodes. Electro-Osmotic Pulse (EOP) technology has been successfully installed in military structures such as family housing, steel reinforced deep structures, and tunnels. EOP has also been implemented on Civilian structures such as residential structures, D.C. Metro Tunnels, and an underground treasury vault. EOP has been shown to prevent moisture seepage into below-grade structures. It is effective at keeping concrete surfaces at or below 50 percent humidity content, meaning the treated space stays dry, indoor relative humidity stays low, and no mold or mildew can grow. This technology has received the 2002 international NOVA award for innovation in construction, and twice nominated for the CERF Pankow award (1999 and 2004). The ERDC research on this technology has also been recognized by the 2004 Army Research and Development Achievement Award.

Abstract: The liquid flow in nanoscale channel under thermal gradient, or so-called thermal transpiration, is studied by Molecular Dynamics Simulation. The phenomenon was realized in two fluid systems which differed from each other in the methods for applying the temperature gradient. One used heat source and the other wall-heating. The channel was periodic and its walls consisted of two different materials: conducting, high energy wall and non-conducting slip wall. It is shown that the liquid in a periodic channel can effectively be driven by the thermal transpiration. Various characteristics of the flow are discussed that include the temperature gradient, velocity profile and liquid structure in the channel.

Abstract: Preliminary results of the use of electroomosis technique for removal of organic contaminants in ceramic filtration porous structure are presented. The method employed provokes the migration of chemical residue and waste retained or adsorbed on the pore surfaces by applying a controlled tension within an electrochemical system. Porous ceramics have been the most common filtration medium employed within a broad range of applications. Conventional cleaning of a ceramic medium is not entirely effective for organic contaminants since they cannot be excluded by size, but retained through chemical affinity to the oxide surface. Under the influence of an electrical current, adsorbed molecules underwent shear stress due to the diffuse moving layer. In their ionic state the specimens are dragged and thus move towards the opposite charged electrode. Phenol was chosen as a standard contaminant and tests carried out using commercial ceramic filtration candles. Relative contaminant concentration was assessed by optical densities (UV-Vis spectroscopy). The results show that removal is proportional for up to 58% of the contaminant in diluted condition.