Osmotic Pressure Difference Research Articles

Adhesion Enhancement of Poly (acrylamide -co- Acrylic Acid)/ Polyethylene Glycol anti-Biofouling Coating using Fly Ash based Geopolymer

Hydrogel has been used as an alternative to replace biocide-based paint in preventing biofouling. However, hydrogel has low adhesion on metallic substrate, hindering its application for coating. Therefore, the aim of this project is to enhance the adhesion strength and anti-biofouling properties of the poly(acrylamide-co-acrylic acid)/polyethylene-glycol hydrogel, poly(AAm-co-AAc/EG) coating via the incorporation of fly ash-based geopolymer that range from 0.5 wt% to 2.5 wt%. The hydrogel coating was synthesised via free radical polymerisation with the aid of N,N-methylenebisacrylamide (MBA) as the crosslinker, and ammonium persulfate (APS) as the initiator. The Fourier transform infrared (FTIR) spectra of the hybrid hydrogel had proved the presence of geopolymer with the availability of significant peaks at 3,294 cm-1 (N-H bond), 2,946 cm-1 (O-H bond), 1,545 cm-1 (C-O-C bond) and 1,113 cm-1 (Si-O-Si or Al-O-Si bond). The average swelling capacity of the hybrid hydrogel coating in distilled water (up to 50,000%) was significantly higher than in artificial seawater (up to 5,000%) due to osmotic pressure difference. The anti-biofouling performance test by using algae (Chlorella vulgaris sp.) suspension showed that the incorporation of 2.0 wt% geopolymer into hybrid hydrogel coating had successfully reduced the algae attachment on the substrate by 92% as compared to the control sample. The adhesion strength of all hydrogel coatings was investigated by using the pull-off adhesion test in accordance to ASTM D4541. The incorporation of 2.0 wt% geopolymer into hydrogel matrices demonstrated an increment of 58% in adhesion strength on steel plate as compared to neat hydrogel. The results showed that geopolymer has the potential to improve the anti-biofouling and adhesion strength of hydrogel coating.

Desalination of brackish water by gelatin-coated magnetite nanoparticles as a novel draw solute in forward osmosis process

ABSTRACT This paper presents the optimization of synthesis of gelatin-coated magnetite nanoparticles (MNPs) and their application as a draw solute in forward osmosis (FO) process. Persicaria bistorta root extract is used as the gelatin crosslinker, and its efficiency is compared with glutaraldehyde as a common crosslinker. Also, the impact of the concentration of gelatin and the draw solution on the osmotic pressure of the produced draw solution has been investigated using response surface methodology. Using Persicaria bistorta root extract as the crosslinker in the optimized conditions, the highest osmotic pressure (1.01 bar) was achieved in a concentration of 7.7%w/v and 14246 mg/l for gelatin and draw solution, respectively. Using glutaraldehyde under the same conditions resulted in osmotic pressure of 1.06 bar which is very close to the pressure found for Persicaria bistorta root extract (1.01 bar), confirming the benefit of the latter as a gelatin crosslinker. Further, using a solution with gelatin-coated MNPs as the draw solution, deionized water as the feed solution, and an osmotic pressure difference of 1.5 in the FO process generated an initial water flux of 1.54 LMH. By repeating the process in nine more cycles, the initial water flux was reduced to 0.365 LMH. These experiments confirm the as-prepared gelatin-MNPs as a promising draw solution in the FO process.

Phase separation in freestanding bilayer lipid membrane induced by osmotic pressure difference

We propose to control the phase separation in freestanding bilayer lipid membranes (BLMs) over Si microwells by applying an osmotic pressure difference. In freestanding BLMs, the liquid-ordered (Lo) phase cannot exist stably because the liquid-disordered (Ld) phase is preferable. When the osmotic pressure outside the microwell is lower than inside it, water permeates the BLM, and the freestanding BLM expands toward the outside. As the area of the freestanding BLM increases, the Lo-phase lipids (saturated lipids and cholesterols) in the surrounding supported BLM are supplied to the freestanding BLM. As a result, the Lo domain is formed in the freestanding BLM. The expansion of the freestanding BLM causes an abrupt bending of the membrane, and the bend acts as a diffusion barrier. The diffusion barrier suppresses the exclusion of the Lo phase lipids in the freestanding BLM, and the Lo domain remains for more than 1 h.

Osmotic pressure as driving force for recovering ionic liquids from aqueous solutions

An emerging challenge occurs for recovering ionic liquids (ILs) because of their exponential growth in academic and industrial applications. We report for the first time to reclaim water-soluble ILs from their aqueous solutions by osmotically driving water to spontaneously permeate through semi-permeable membranes. Theoretical simulation indicates a weak hydrability of ILs and a tendency to form micelles in water. We thus demonstrate a significant difference in osmotic pressures between the aqueous solutions of ILs and inorganic salts. Four categories of broadly representative ILs are continuously recovered from their diluent aqueous solutions (~1 wt%) with semi-permeable membranes. Eventually, a record-high concentration up to 58–78 wt% is achieved in this work. Our strategy integrates superiorities of low energy consumption, universal applicability toward ILs, diversified selection of semi-permeable membranes, almost unattenuated water flux and high rejection to ions, hopefully providing new insights into the authentic “green” industrial applications of ILs.

Shrinkage of Cholesteric Liquid Crystalline Microcapsule as Omnidirectional Cavity to Suppress Optical Loss

AbstractCholesteric liquid crystalline (CLC) emulsions are the easiest 3D omnidirectional laser resonators to fabricate. To exploit the full potential of CLC emulsions as distributed Bragg reflection (DBR) mode laser resonators, monodispersed water‐in‐CLC‐in‐water double emulsions (CLC microcapsules) have higher performance scalability than simple CLC droplets. If laser dyes are concentrated at the center of CLC microcapsules, emitted light from the dye is 3D confined. When water is squeezed from the inner phase of a CLC microcapsule comprising an aqueous laser dye solution by means of osmotic pressure difference from the outer phase, the DBR lasing threshold of the CLC microcapsule is reduced. The shrinkage of the inner droplet contributes not only the simple reduction of the cavity length but also the suppression of the optical loss to reduce the lasing threshold. The reduced optical loss is beneficial to realize various devices: optical manipulation, photonic cross communications, and biochemical, light, and temperature sensing. Their flexible photonic structures are suitable for emerging and future optical devices like wearable optical devices.

Development and Evaluation of Controlled and Simultaneous Release of Compound Danshen Based on a Novel Colon-Specific Osmotic Pump Capsule

In the study, we developed a novel oral dosage form of Compound Danshen to resolve the problems of low bioavailability, disequilibrium in drug release, and stomach degradation of active components of Compound Danshen in conventional formulas. A colon-specific osmotic pump capsule (COPC) of Compound Danshen was prepared using a semipermeable shell with the core components. Using a single-factor method, we obtained the optimal formulation that consisted of Salvia miltiorrhiza extract, Panax notoginseng extract, Borneol, sodium chloride, polyethylene oxide wsr-N10, hydroxypropyl-β-cyclodextrin, and ludipress. Moreover, in vitro dissolution test showed simultaneous releases of active ingredients from Compound Danshen COPC over 12h at pH7.8, displaying zero-order release characteristics. The impetus of drug release mainly depended on the difference in osmotic pressure across the capsule shell. Next, scanning electron microscopy showed morphological changes in the capsule shell during the dissolution test. More importantly, pharmacokinetic study in beagle dogs indicated that relative bioavailability was 330.58% and retention time was greatly prolonged in Compound Danshen COPC, compared with those in marketed Compound Danshen tablet products. Finally, in vivo imaging studies in beagle dogs showed that COPC was stable in gastrointestinal tract and the drug was specifically released in the colon region. A colon-specific osmotic pump capsule (COPC) of Compound Danshen was developed and optimized to achieve simultaneous zero-order release of multiple active components of Compound Danshen in the colon. More importantly, the COPC have proved to improve the bioavailability and prolong the retention time of Compound Danshen, compared with those in a marketed product.

V-ATPase subunit B plays essential roles in the molting process of the Chinese mitten crab, Eriocheir sinensis.

ABSTRACTVacuolar ATPase (V-ATPase) is a proton pump driven by ATP hydrolysis, and it plays an important role in numerous biological processes, such as protein degradation and synthesis, cell growth, and cell autophagy. The V-ATPase subunit B (VATB) is a conservative and regulatory subunit required for ATP hydrolysis during proton pumping. The VATB of Eriocheir sinensis (EsVATB), which includes an open reading frame (ORF) length of 1467 bp encoding 489 amino acids, was cloned to unveil the biological function of VATB during the molting process of crustaceans. Spatial and temporal expression profiles showed that EsVATB was highly expressed in the posterior gill accompanied with the highest osmotic pressure in the premolt (PrM) stage. Meanwhile, the highest expression level of EsVATB was identified in the hepatopancreas and heart during the postmolt stage and epidermis in the intermolt stage, indicating that EsVATB may perform diverse biological functions in different tissues during the molting process. The individual crabs in the interference group showed a high mortality rate (74%) and a low molting rate (26%) and failed to form a new epicuticle in the PrM stage. Meanwhile, a significant difference in osmotic pressure was identified between the interference and control groups. Our results indicate that EsVATB is an indispensable functional gene that may participate in osmoregulation and help with the new epicuticle formation during the molting process of E. sinensis.

Experimental and Numerical Analysis on Swelling and Hemolysis of Human Red Blood Cells due to Osmotic Pressure Difference

Experimental and Numerical Analysis on Swelling and Hemolysis of Human Red Blood Cells due to Osmotic Pressure Difference

Development of a microfluidic route for the formation of gellan-based microgels incorporating jabuticaba (Myrciaria cauliflora) extract

Gellan microgels incorporated with jabuticaba extract were produced by external gelation of monodisperse water-in-oil (W/O) emulsions. This extract, rich in anthocyanins, has shown antioxidant effect and benefits associated to intestinal issues. The W/O emulsions were produced using a three-dimensional microfluidic device operated in an intermittent dripping regime flow. Microgels were obtained from external gelation of emulsions by calcium ions present in the continuous phase. Our results showed how to produce and control the microgel diameter and polydispersity by varying the flow rate of continuous and dispersed phases. Diameter of microgels ranged from 185 μm to 342 μm, and coefficient of variation values varied between 1.6 and 8.6%. The low stability of microgels loaded with jabuticaba extract was mainly associated with both the low gellan concentration and the osmotic pressure difference during storage. In spite of this, the microfluidic route proposed can potentially be used to incorporate and protect anthocyanins extracts and might be extended for other hydrophilic molecules.

Thermodynamic optimization of Multistage Pressure Retarded Osmosis (MPRO) with variable feed pressures for hypersaline solutions

Salinity gradient processes, such as Forward Osmosis and Pressure Retarded Osmosis, have been proven to be promising technologies for reducing the energy consumption in water treatment processes, for energy production, and for energy recovery. Based on the thermodynamic concepts, specifically Gibbs' Free Energy of Mixing, the concentration of the draw solution plays an important role in determining whether the selected salinity gradient process is economically feasible or not. An increase in the salinity of a draw solution does not only increase the osmotic pressure difference between the draw and feed solutions, but also allows a higher hydraulic pressure to be applied on the draw solution, which together greatly increases the volumetric flux of the draw solution per single pass when PRO is used. Even though higher power densities can be achieved by applying higher hydraulic pressures on the draw solution, this requires greater mechanical stability of the membrane to be able to withstand these higher hydraulic pressures. In order to increase the mechanical stability of the membranes, generally, thicker support layers can be applied, which have a direct negative impact on membrane permeability. Therefore, there is a limitation to the salinity of the draw solution which can be used in the PRO processes. This being dependent on the concentration of the hypersaline solution and hence overall hydraulic pressure, necessitating the use of an ultra-thick support layer for maximum energy production and/or recovery. In this theoretical and simulative optimization of the PRO process, we achieved the optimum energy recovery from a hypersaline solution (TDS ~ 300,000 mg/l) by using a multistage PRO (MPRO) system which included implementing variable applied feed pressures to each stage. The results showed that the volumetric flow rate of the hypersaline draw solution increased by up to a factor of 10 during the MPRO process in single pass, and the concentration of the hypersaline draw solution diluted up to 10× accordingly. Energy conversion efficiency of osmotic pressure to hydraulic pressure was found to be around 10% without variable feed pressure and approximately 20% with variable feed pressure.

Various aspects of the exploitation of marine current energy with tidal turbines

The main purpose of this paper is to present a short review of the actual progress on the tidal energy and on the tidal energy convertors: turbines, dam systems, oscillating wings and their operation characteristics. The energy of the oceans: the tides, the waves, the difference of osmotic pressure between the fresh water and that of the oceans, the thermal gradient in the depths of the oceans, the sea currents, represents a huge reservoir of electricity estimated at an annual production of 120.000 TWh. The energy of the tides could provide a lot of electricity, but a power station of this type causes damage to the environment of the estuary where it is built and to its wild life because it prevents the passage of fish. Tidal turbines could be an alternative solution in environment protection.

Renewable energy powered membrane technology: Impact of solar irradiance fluctuation on direct osmotic backwash

Direct osmotic backwash (OB) during solar energy fluctuations is an important observation in directly coupled, battery-less solar energy powered nanofiltration/reverse osmosis (NF/RO) membrane systems. OB occurs spontaneously and has the potential to induce membrane self-cleaning. The impact of controlled solar irradiance fluctuation conditions, feed water salinity (1–10 g/L) and membrane type (NF membrane NF270, RO membrane BW30) on OB were investigated by periodic step-response tests. The objective of this research was to investigate the OB mechanism under solar irradiance fluctuations. The results show that solar energy fluctuations lead to a change of filtration hydrodynamic conditions (feed flow rate, applied pressure), operating time, and permissible backwash time. This results in variations of OB driving force which is determined by the osmotic pressure difference during filtration. High feed water salinity and solar irradiance before fluctuation enhance the OB process, while relative high solar irradiance during fluctuation weakens the OB process. Furthermore, the BW30 membrane shows a higher OB flow rate and less accumulated volume than NF270. This was attributed to the higher salt retention of BW30 resulting in a larger backwash driving force and much lower flux of BW30 which in turn caused a thinner CP layer. These findings indicate that solar irradiance fluctuation conditions may potentially delay fouling and hence enhance the reliability and robustness of battery-less photovoltaic-membrane systems.

An exploration of the rapid transformation method for Dunaliella salina system

As a new expression system, Dunaliella salina (D. salina) has bright prospects and applications in various fields. However, its application is currently restricted because of the low expression and instability of foreign gene in D. salina cells. During genetic operation, transformation is a crucial step for genes expression in D. salina system. Although several transformation methods are existing currently, many inherent deficiencies and limitations still can be found in actual practice. Thus, we attempted to set up a rapid transformation method using the change of salt concentrations for D. salina. Based on osmotic pressure difference, exogenous genes can be spontaneously transferred into D. salina cells. After that, transformed D. salina cells were subjected to histochemical and molecular analysis. The results showed that the reporter gene, beta-glucuronidase genes were successfully expressed in the positive transformants, and detected in all of transformed cells by PCR analysis. Moreover, different transformation parameters, containing the salt gradient, time, dye dosage and Triton X-100 concentration, were optimized to obtain an optimal transformation result. Taken together, we preliminarily established a rapid transformation method with the features of fast, simple, economic, and high-efficient. This method will provide a strong genetic manipulation tool for the future transformation of D. salina system.

An Overview of Simulated Hydrogel Behaviour under Various Kinds of Stimulation

AbstractPolyelectrolytic gels placed in aqueous solution show effects under various kinds of stimulation. The stimuli could be e.g. of chemical, electrical, mechanical or thermal nature. The hydrogels react via uptake or delivery of mobile ions and solvent, and they show enormous swelling capabilities. This multifunctional behaviour is potentially attractive for chemo‐electro‐mechanical energy converters or for the use as actuators or sensors. In the present research, anionic and cationic hydrogels are investigated, which means that the polymer network contains anionic or cationic bound charged groups. The chemical stimulation is applied by a change of boundary conditions in the solution bath for the salt concentrations. The electrical stimulus is realized by incorporating electrodes between which an electric potential difference is applied. The mechanical stimulus is realized by prescribed displacements at a boundary of the hydrogel itself. The thermal stimulus is applied as transient temperature change over the whole domain, incorporating temperature‐dependent material parameters and osmotic pressure differences. The reactions of the hydrogel differ depending on the sensitivity of the gel to the applied stimulus. The incorporated chemo‐electro‐mechanical model enhanced with thermal dependencies is capable of giving local concentrations, electric potential and mechanical displacements.

Influence of osmotic mediation on permeation of water in reverse osmosis: Experimental and numerical analysis

Osmotically mediated reverse osmosis (RO), whose concept is to lower the osmotic pressure difference (Δπ) across the membrane by supplying a “mediate” solution of low or equal concentration (relative to feed solution concentration) in the permeate side, has been recently suggested as a viable way to treat hypersaline brines. However, most of the studies on the osmotically mediated RO process have focused on numerical analyses or simulation. Accordingly, we experimentally delved deeper into the permeation of water through the membrane and numerically analyzed this permeation for the process. When Δπ across the membrane was mediated in the bulk phase for the feed solution of 0.2 to 1.2 M, the water flux significantly decreased with the feed solution concentration. Specifically, for the feed solutions of 0.6 and 1.2 M, the water fluxes of 22.1 and 5.76 L m-2 h-1 were obtained at ΔP of 40 bar and Δπ of 0 bar in the bulk phase, respectively. Numerical results showed that even when Δπ was mediated in the bulk phase, effective osmotic pressure difference (Δπeff) for each concentration increased with ΔP increase and increased further with the feed solution concentration. Nevertheless, the osmotically mediated RO process can be regarded as hydraulic dilution process. By virtue of this process, the high-pressure single stage RO process may be replaced by a moderate-pressure two-stage RO process for low-energy process.

Formation of wax walled microcapsules via double emulsion using cross membrane emulsification at elevated temperatures

A novel micro encapsulation process has been developed via a double emulsion of water in oil in water, whereby the oil is molten during the process and is then solidified to form a solid wall afterwards. This has the potential for an improved encapsulation technique for hydrophilic components. A range of materials was used, including hexadecane, lanolin and cetyl palminate. Temperature controlled, cross membrane emulsification was used to ensure a narrow size distribution. Calculations of permeability, based on the leakage of fluorescein solutions, indicated a much higher rate that would be expected from such a hydrophobic, crystalline wall. Faster cooling gave rise to higher permeability. These suggest that pores are forming in thin walls during the solidification process and indicate the importance of process conditions on wall formation. Osmotic pressure differences are also a potential contributor.

Shape Recovery of Spherical Hydrogen-Bonded Multilayer Capsules after Osmotically Induced Deformation.

The mechanical properties of microparticles intended for in vivo applications as drug delivery vehicles are among important parameters that influence their circulation in the blood and govern particle biodistribution. We report on the synthesis of soft but mechanically robust spherical capsules via a hydrogen-bonded multilayer assembly of (poly(N-vinylpyrrolidone), Mw = 10 000 g mol-1) with (poly(methacrylic acid) Mw = 100 000 g mol-1)) (PVPON/PMAA)n in methanol using 4 μm nonporous silica microparticles as sacrificial templates, where n = 5 and 10 and represents the bilayer number. The mechanical properties of (PVPON/PMAA)n spherical capsules were assessed using the osmotic pressure difference method and resulted in an elasticity modulus of 97 ± 8 MPa, which is in the range of Young's modulus for elastomeric networks. We also found that hydrogen-bonded (PVPON/PMAA)10 capsules demonstrated almost complete recovery from a concave buckled inward shape induced by the osmotic pressure difference from the addition of polystyrene sulfonate (PSS) to the capsule solution to their initial spherical shape within 12 h after the PSS solution was rinsed off. The permeability measurements through the capsule shell using fluorescently labeled dextran molecular probes revealed that the average mesh size of the hydrogen-bonded network assembled in methanol is in the range of 3 to 9 nm and is not permeable to FITC-dextran with a molecular weight of >40 000 g mol-1. Our study shows that physically cross-linked polyelectrolyte multilayer capsules are capable of withstanding large deformations, which is essential to the development of adaptable particles for controlled delivery.

Nonswellable and Tough Supramolecular Hydrogel Based on Strong Micelle Cross-Linkings.

Because of the difference in osmotic pressure, most tough hydrogels swell under physiological conditions, which seriously weakens their mechanical properties, limiting their applications in biomedicine. Herein, a novel strategy based on strong and high-density micelle cross-linkings is proposed to prepare nonswellable and tough hydrogel. To realize a strong micelle cross-linker, the synergetic effect of hydrophobic and quadruple hydrogen-bonding interactions is employed by introducing an alkyl chain-protected ureido pyrimidinone moiety into a segmented copolymer backbone. The length of the alkyl is the key factor in determining the strength of the hydrophobic interaction, which was carefully tailored to gain micelles with high strength and suitable solubility. A supramolecular hydrogel was formed in situ by simply linking micelle cross-linkers with poly(ethylene glycol) chains. The strong and high-density micelle cross-linkings restrain multiple effective chains outside the micelle from stretching during swelling, and the deformability of micelle cross-linkings disperses the local stress to maintain the network with high cross-linking density upon loading. Therefore, the hydrogel exhibited an outstanding nonswelling behavior under physiological conditions and excellent mechanical properties with a compressive strength of 4 MPa. The rapid in situ gelation also facilitated injection and cell encapsulation. Meanwhile, it also showed good tissue adhesion, cytocompatibility, and suitable degradability. This novel and facile strategy can offer new insights into the exploitation of cross-linkings to prepare nonswellable hydrogels for biomedical applications.

Shear resistance performance of low elastic polymer microspheres used for conformance control treatment

Low elastic polymer microsphere (L-EPM) has been proposed as a functional polymer microsphere these years. L-EMP has the excellent deformation ability in the porous medium due to the low storage modulus. Herein, one kind of L-EPM with storage modulus (G′) of 23.6 Pa was prepared by inverse suspension polymerization. The shear resistance of L-EPM was researched by using core flooding experiment and high shear rate emulsifier. The conformance control behavior of L-EPM was investigated by using double parallel sandpack flooding experiment. The results showed that L-EPM was a kind of swollen particle gel with three-dimensional net structure and contained amide, carboxyl, and sulfonate groups. The mechanism of water swelling property was mainly due to the formation of hydrogen bonds, hydrolysis of hydrophilic groups and the diffusion caused by osmotic pressure difference. Compared with high elastic polymer microspheres (H-EPM) and low elastic preformed particle gel (L-PPG), L-EPM had better shear resistance in the porous medium and the well casing perforation. In addition, the critical shear points of L-EPM was proposed in this work. Due to the better shear resistance and deformation ability, the conformance control behavior of L-EPM showed that L-EPM was a promising conformance control agent in the heterogeneous reservoirs.

Aqueous Two-Phase System Formation in Small Droplets by Shirasu Porous Glass Membrane Emulsification Followed by Water Extraction

By utilizing water transport phenomena between two different water-in-oil (W/O) emulsion droplets through continuous oil phase, we developed a novel method of aqueous two-phase system (ATPS) formation in small droplets prepared by Shirasu porous glass (SPG) membrane emulsification technique. When we mixed W/O emulsion droplets containing poly(ethylene glycol) (PEG) and dextran (DEX) at concentrations below the threshold of the phase separation, with droplets containing other solutes at high concentrations, water extraction from the droplets containing PEG and DEX to those containing the other solutes occurred, owing to the osmotic pressure difference. This effect increased the concentrations of PEG and DEX in the droplets above the phase separation threshold. We demonstrated the feasibility of the preparation method by varying the pore sizes of the SPG membranes, the solutes, and their concentrations. Only when the concentration of the solute was high enough to extract sufficient amounts of water did the homogeneous disperse phase consisting of PEG and DEX in droplets turn into a PEG-rich phase and DEX-rich phase, showing ATPS. This result was irrespective of the solute itself and pore size of the SPG membrane. In particular, we successfully demonstrated monodisperse ATPS droplets with diameters of approximately 10 μm under a certain condition.