Concentration Polarization (CP)

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Investigation of concentration polarization in a cross-flow nanofiltration membrane: Experiment and CFD modelling

Investigation of concentration polarization in a cross-flow nanofiltration membrane: Experiment and CFD modelling

During the recent decades, various membrane techniques have raised in the treatment of saline water. Development of membrane technology has the potential to facilitate the drinking water supply. In this technology, the nature of semipermeable membranes is the main cause of separation. Accumulation of particles in the feed channel is known as the fouling phenomena which may fall into several categories including organic, colloidal, inorganic, and microbial fouling. Flux decline can be a possible result of the membrane fouling and concentration polarization (CP) phenomena [1–3] Researchers have shown that the CP caused a drop in the membrane performance up to 30% [4]. Various methods have been proposed for controlling the CP, two of which are declining the water flux (J) and increasing the mass transfer coefficient (K). A number of previous studies have also reported that increasing the liquid cross-flow velocity, improvement of hydrodynamic properties, and promoting turbulent flow can all help to disrupt the CP [5]. Generally, common methods applied in the literature for controlling the CP phenomena are unsteady state flow [6], flushing [7], gas/liquid two-phase unsteady flow [8–10], membrane vibration [11], and DC electric field [12].
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Concentration Polarization to Measure the Nanopore Accessibility of Fluid Catalytic Cracking Particles

Concentration Polarization to Measure the Nanopore Accessibility of Fluid Catalytic Cracking Particles

From Figures 8 up to and including 12 it can be seen that the time-average of the maximum brightness in each polar- ization region decreases for higher concentrations, indicating that ICP effects decrease for larger concentrations. This cor- responds to the theory of ionic concentration polarization: the electrical double layers of the nanopores of the FCC par- ticle get thinner for higher concentrations of KCl, decreasing the surface conductivity of the EDLs and making the bulk electrolyte conductivity more dominant in the equation for the Dukhin number. This theory is supported by the graph of Figure 13. In this graph, the Dukhin length, a number cor- responding to the Dukhin number divided by the nanopore size, and the Debye length, a number proportional to the EDL thickness, are plotted versus the concentration of KCl. The Dukhin length decreases for higher concentrations, which is in correspondence with the previous shown results. If the Dukhin number would be constant for every concentration, the nanopore size that would be affected by ICP would be bigger for higher concentrations as the EDL is thinner, re- sulting in less ICP effects.
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The Estimation of Feed Solution Composition Influence on Concentration Polarization Layer Resistance during Reverse Osmosis | Journal of Engineering Sciences

The Estimation of Feed Solution Composition Influence on Concentration Polarization Layer Resistance during Reverse Osmosis | Journal of Engineering Sciences

It should be noticed, that influence of solution compo- sition on concentration polarization layer resistance value under experimental conditions in particularly considered salts and their concentrations was lower than the influ- ence of hydrodynamic conditions which was investigated in work [3]. Moreover, the obtained in that work behavior is confirmed. In particular, the value of concentration layer polarization resistance is decreased with increasing the Reynolds number (Figure 8) as it was predicted by the film theory of concentration polarization [1, 2].
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Paper-based ion concentration polarization device for selective preconcentration of muc1 and lamp-2 genes

Paper-based ion concentration polarization device for selective preconcentration of muc1 and lamp-2 genes

Over the past several decades, the separation and con- centration of biomolecules including DNA and proteins have been developed for micro-scale assay such as genet- ics, disease diagnostics and point-of-care applications [1]. Recently, novel biomolecules separation and detection methods based on ion concentration polarization (ICP) phenomena have been extensively developed [2–6]. The ICP phenomena that is generated near the interface of a microfluidic channel and perm-selective nanojunction causes the depletion zone at the anodic side of the mem- brane. Due to electro-neutrality requirement at low con- centration inside the depletion zone, any charged species were rejected into the ion depletion zone so that the molecules were accumulated at the boundary of the zone with a proper application of tangential electric (or pres- sure) field. Unfortunately, the fabrication of conventional ICP devices still have demanded complex photolithog- raphy and high cost reactive ion etching. Moreover an interfacing to downstream analyzer would be restricted
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Concentration Polarization pdf

Concentration Polarization pdf

a measure of the in S uence of convection relative to the in S uence of diffusion in the boundary layer. The results of this calculation are shown in the very informative Figure 3, which con R rms that the con- centration polarization modulus is smaller than 1 (boundary layer depletion) if the permeating com- pound is enriched in the permeate and larger than 1 (boundary layer build-up) if the permeating com- pound is depleted in the permeate. The concentration polarization modulus increasingly deviates from unity as the ratio v p / k bl increases, that is, as the S ux

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The Research of the Flow Characteristics in Spiral Membrane Separator

The Research of the Flow Characteristics in Spiral Membrane Separator

In addition to these studies, many more researches on the curved membrane channels which provide a high mixing potential by secondary or Dean vortices was performed. Based on the Dean vortex theory a novel vortex-generating tubular nanofiltration element was designed by Hanuman Mallubhotla et al. [10]. They used the experimental results to confirm that the flow in the spiral tube produces Dean vortices to enhance the reverse migration of solute, which can reduce concentration polarization and membrane fouling.

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Synthesis and Characterization of Ni-Co Electrocatalyst for Hydrogen Evolution Reaction in Acidic Media

Synthesis and Characterization of Ni-Co Electrocatalyst for Hydrogen Evolution Reaction in Acidic Media

Fig. 5 shows that the resistance of the solution is very small, and there is no straight line at a 45° angle in the low frequency region, illustrating no concentration polarization of reactive ions occurs. The semicircle arc impedance complex plane plot shows that the polarization of the electrode potential is entirely generated by electrochemical steps. According to the literature of HER[ 20] and the Tafel slope shown in Table 1, b ranging from 0.165 to 0.173 V dec -1 , higher than 0.118V dec -1 , it can be derived that HER takes place by the Volmer- Heyrovsky mixing mechanism. It is known that the charge transfer process is the interface between electrocatalyst and electrolyte, which is attributed to a charge transfer resistance (Rct ) and constant phase element (CPE) [36,37,38]. The semicircle diameter of EIS of the Ni 64.4 Co 35.6 , Ni 79.9 Co 20.1 , Ni 82.5 Co 17.5 and Ni electrodes increases sequentially,
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Degradation of Passive Film on Low-Nickel Stainless Steel in Groundwater with Different Concentration of Chloride Ions

Degradation of Passive Film on Low-Nickel Stainless Steel in Groundwater with Different Concentration of Chloride Ions

and non-carbonated pore solutions, where the chloride concentration was varied. The experimental results indicated that, in extremely aggressive solutions, the corrosion resistance of 204Cu was significantly lower than that of austenitic stainless steels. Further observations in mortars confirmed that using the low-nickel 204Cu (rather than the 304 stainless steel) for structures exposed to the same environment yielded a 35%–40% reduction in the initial cost. Similarly, Monticelli [15] investigated the corrosion process of low-nickel and 304 austenitic stainless steels carbonated and exposed for 650 days to increasing amounts of chloride in alkaline-activated fly ash mortars. The findings also confirmed the excellent performance of the new low-nickel stainless steel, where the pitting resistance was only slightly lower than that of 304 stainless steel. Serdar [16] conducted long-term (i.e., 2 year) corrosion measurements via electrochemical impedance spectroscopy at the open circuit potential, on steels embedded in mortar with chloride media. The results suggested that the open circuit potential (E OCP ) of new low-nickel stainless steels approached that of traditional austenitic stainless steels, with
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Fine-tuning the efficiency of para-hydrogen-induced hyperpolarization by rational N-heterocyclic carbene design

Fine-tuning the efficiency of para-hydrogen-induced hyperpolarization by rational N-heterocyclic carbene design

substrate dissociation has previously been predicted to be lower than those commonly observed 17 and is confirmed by these data. Hence, the effects of magnetic relaxation during the lifetime of the active catalyst are important because it is destructive to the SABRE process 17,18,26 . This effect is decreased here by use of 2 H- labelling in the NHC ligand and accounts for the superior per- formance of d 16 -23. We have demonstrated that the spin−spin couplings vary within these catalysts. However, as the final level of polarization is also associated with the rate of substrate dis- sociation and spin relaxation 18 , optimization will be needed for
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Influence of PVP and PEO on Cloud Point of Poly (oxyethylene) 10 Oleyl Ether (Brij 97): A Thermodynamic Approach

Influence of PVP and PEO on Cloud Point of Poly (oxyethylene) 10 Oleyl Ether (Brij 97): A Thermodynamic Approach

The influence of PVP (Mol.wt.40000) on the CP of Brij-97 at different concentration have been studied. The results are given in Table 2. These results indicating that the cloud point of surfactant polymer mixtures decreases with increasing concentration of surfactant. For 0.5 wt% of Brij-97 CP increases from 56.5 to 57.10C with increasing concentration of PVP from 0.005 to 0.05wt% of PVP. While for 1% to 5% of Brij-97 CP decreases considerably with increasing concentration of PVP from 0.005 to 0.5wt%. As the surfactant concentration increases in surfactant–
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Hygroscopicity- and Size-Resolved Measurements of Submicron Aerosol on the East Coast of the United States.

Hygroscopicity- and Size-Resolved Measurements of Submicron Aerosol on the East Coast of the United States.

Figure 1.6 Time series summary of the deployment. Gaps in the data indicate that the instrument was sampling on a mode not mentioned here or that the instrument was down. Top to bottom: (a) Wind speed (orange) and direction (brown). Wind blowing from the continental sector is shaded in gray; (b) aerosol size distribution; colors represent spectral concentration; (c) Total particle concentration from the ambient CPC-1 (gold) and from the SMPS integrated dry size distribution (purple). The Marine Period 1 and 2 are shaded in blue and the continental period is shaded in green; (d) Fraction of particles in the sodium-
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OXIDATIVE DEGRADATION OF 2-CHLOROPHENOL BY PERSULFATE

OXIDATIVE DEGRADATION OF 2-CHLOROPHENOL BY PERSULFATE

The 2-chlorophenol (2-CP) was purchased from Sigma (St Louis, MO, USA). Acetic acid, ammonium persulfate, sodium hydrogen phos- phate heptahydrate, sodium dihydrogen phos- phate dihydrate, iron(II) sulfate heptahydrate and copper(II) sulfate pentahydrate were from Avan- tor Performance Materials (Gliwice, Poland). HPLC-grade acetonitrile was obtained from Ac- ros Organics (Geel, Belgium). Stock solutions of 2-CP (1 mmol L -1 ), (NH

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Design and development of fast Melting Tablets of Terbutaline Sulphate

Design and development of fast Melting Tablets of Terbutaline Sulphate

In today’s world when air pollution is rampant people of all ages and classes are vulnerable to diseases related to respiratory system. Asthma is one such common disease of the respiratory system to have a big influence on human race. This disease affects people of all age; young or old all alike. This disease is caused by the constriction of the airways particularly bronchi. Terbutaline Sulphate is a selective beta -2 adrenoreceptor agonist and used in acute treatment of bronchial asthma since it help in dilating the constricted bronchi, Terbutaline sulphate is used in various other forms of chronic obstructive pulmonary diseases. Terbutaline sulphate is a short acting bronchorelaxant and is given in all the major routes of administration. The peak plasma concentration of Terbutaline sulphate is 1.2µg/ml for every milligram of oral dose. A lesser amount than that of oral administration reaches the systemic circulation via inhalation route, since it is difficult to coordinate the breathing when the pump is pressed; this creates problems in the treatment of the patient. Also pumps are expensive as compared to solid oral dosage form 1,2 .
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Electrochemical Impedance Spectroscopy Study on Corrosion Inhibitor for Reinforced Concrete

Electrochemical Impedance Spectroscopy Study on Corrosion Inhibitor for Reinforced Concrete

decline in the phase angle could not be found in series CA II. Therefore, the efficiency of inhibition was lower here. Considering the ascending trend of impedance values and, accordingly, the polarization resistance with increasing concentration of both inhibitors, exhibited in the Bode-modulus part, it is confirmed that calcium nitrite could increase the corrosion resistance of the samples [28, 29]. Nevertheless, it should be noted that the time span of series CA II from the start of corrosion to this moment when the ratio of chloride to inhibitor is less than 1 is 5 weeks longer than that in series CA I, namely, 2 weeks.
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Multimodal label-free imaging of living dermal equivalents including dermal papilla cells

Multimodal label-free imaging of living dermal equivalents including dermal papilla cells

In the current study of extracellular matrix remodel- ing, we used CP OCT and MPT to analyze the ability of DP cells to contract three-dimensional collagen gels in vitro. Currently, extracellular matrix remodeling by DP cells has been very poorly investigated. Moreover, it was thought that the contraction ability of DP cells when compared with FBs displayed opposite trends. It was also demonstrated that FBs and DP cells are very comparable in their contraction ability, and DP cells show the same fractional forces as FBs. Immunohistochemical analyses indicate the presence of the corresponding cytoskeletal proteins, vimentin, tubulin, and actin in both types of cells [36]. Hill et al. have shown that both dermal sheath (DS) and DP cells seeded into rat tail type I collagen contracted the collagen lattice to a similar degree, with both displaying significantly enhanced contractile ability over dermal FBs. DP cells and DS cells expressed more α-SMA and were more contractile than dermal FBs [37]. However Almond-Roesler et al. revealed a significantly lower capacity of DP cells to reorganize extracellular matrix components than that of dermal FBs and, more- over, the DP cells lysed the collagen lattices completely after 48 h in culture [38]. In our work, the gel contrac- tion was very similar for both dermal FBs and DP cells, showing that DP cells can cause the same manner of col- lagen gel structuring as FBs. In both types of cell, visible collagen fibril formation started at 3–7 days with the maximum elevation of the CP OCT and SHG signals being registered from day 10. Moreover, in both cases, between days 12 and 14, we detected the type of higher
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Improved Measurement Method of Circularly Polarized Antennas Based on Linear Component Amplitudes

Improved Measurement Method of Circularly Polarized Antennas Based on Linear Component Amplitudes

Two methods about measuring ARs of CP antennas based on linear compo- nents are discussed in [2]. The first method is to measure one set of orthogonal LP amplitudes and phases by utilizing linearly-polarized auxiliary antennas. Another method is to measure only two sets of orthogonal LP amplitudes with- out phase measurement. ARs and patterns are separately obtained in [3] [4] [5] by using the first method. However, the phase measurement is limited by mea- suring equipment and the error is relatively large in fact. The characteristics of ARs are got by utilizing the second method in [6] and [7]. It is not necessary to measure phase information, while amplitudes can be measured accurately. As a result, the measuring accuracy of AR is improved. But this method also has a problem that the rotation sense of the co-polarization cannot be determined due to the absence of the phase information. There is no analysis about this problem in the related records.
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A CP Antenna of Wide Half-Power Beamwidth for UHF RFID Near- and Far-Field Applications

A CP Antenna of Wide Half-Power Beamwidth for UHF RFID Near- and Far-Field Applications

In this Letter, a multiservice antenna based on magnetic coupling in near-field regions and circular polarization (CP) in far-field is proposed for RFID applications in UHF band. The antenna also achieves high radiation efficiency up to 98%–99% and 102 ◦ of 3-dB beamwidth for scanning for large regions. 100% read rate of near-field tag is within 25 mm, and read distance for far-field tag is up to 1 m. The multiservice antenna has good prospect in both near-field and far-field applications.

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Optical fiber Hemoglobin concentration sensor
based laser polarization

Optical fiber Hemoglobin concentration sensor based laser polarization

The field of fiber optics has undergone tremendous growth and advancement over the last 25years. Initially conceived as a medium to carry light and images for medical endoscopic applications, optical fibers were later proposed in the mid 1960’s as an adequate information carrying medium for telecommunication applications[ 1 ] .More recently, and especially since 1980, a great deal of research in optical fibers has been dedicated to sensing, and again the medical field found good opportunities for developing very promising sensors [2].Optical –fiber biosensors offer several advantages over other biosensors : small size, flexible geometry , remote working capability , and noise immunity which make them ideal for clinical applications, environmental monitoring , and process control with easy operation.[3 ]. A novel method and instrumental system to determine the total protein concentration in a liquid sample is described by P.V. Preejith1 et.al [ 4 ] It uses a fiber optic total protein sensor (FOPS) based on the principles of fiber optic evanescent wave spectroscopy.The Hemoglobin (Hb) concentration in human blood is an important parameter to evaluate the physiological condition. A hemoglobin test reveals how much hemoglobin can be found in the blood. With this information anemia (a low hemoglobin level) and polycythemia vera (a high hemoglobin level) can be a diagnosed and monitored. It is also possible to observe imminent postoperative bleedings and autologous retransfusions. Currently, invasive methods are used to measure the Hb concentration. For this purpose blood is taken and analyzed. The disadvantage of this method is the delay between the blood collection and its analysis, which does not allow a real- time patient monitoring in critical situations. A non-invasive method allows pain free online patient monitoring
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Corrosion Inhibition of Aluminum in Hydrochloric acid Solution Using Ceria Doped Polyvinyl Chloride Nanofiber.

Corrosion Inhibition of Aluminum in Hydrochloric acid Solution Using Ceria Doped Polyvinyl Chloride Nanofiber.

nanofibers with the ability to scale- up to fabricate large volumes of the resulted nanocomposite [15]. It has been widely used in many applications, such as biomedical, gas sensors, electronics, and corrosion inhibition [16-21]. In this work, we report the synthesis of ceria NPs, and then embedded in-situ in polyvinyl chloride (PVC) nanofiber coating on aluminum substrates as a collector in the electrospinning process. The effect of polymeric coat on the corrosion behavior of aluminum in 0.1M HCl was examined using potentiodynamic polarization, and impedance spectroscopy. The surface of aluminum, and the Polymeric coated aluminum surface before, and after immersing in HCl were characterized by using scanning electron microscope (SEM). The synthesized nanocomposite has been optically characterized using absorbance spectroscopy, direct bandgap calculations, and fluorescence spectroscopy. These optical characterizations can give proof of the existence of oxygen vacancies inside the crystalline structure of ceria nanoparticles; which can adsorb the free radicals, and consequently reduce the rate of corrosion [22].
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Corrosion by Polyaniline/Salicylaldehyde Modified Chitosan in Hydrochloric Acid Solution

Corrosion by Polyaniline/Salicylaldehyde Modified Chitosan in Hydrochloric Acid Solution

surface area) as auxiliary electrode and saturated calomel electrode (SCE) as the reference electrode. The Q235 steel, sized 1 cm  1 cm, was embedded in polytetrafluoroethylene (PTFE) and used as working electrode. The working electrodes were immersed in 100 mL 1.0 M HCl solutions without/with different concentrations of inhibitors (100 ppm, 200 ppm, 300 ppm, 400 ppm) for 1 h. The anodic and cathodic polarization curves were recorded at a scan rate of 1 m/Vs with electrode potential from -0.8 V to 0 V. The inhibition efficiency and corrosion rate were calculated using following equation:
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