Artículos de revistas: "Hydrophilic solute"

1

Monroe, Jacob I., Sally Jiao, R. Justin Davis, Dennis Robinson Brown, Lynn E. Katz y M. Scott Shell. "Affinity of small-molecule solutes to hydrophobic, hydrophilic, and chemically patterned interfaces in aqueous solution". Proceedings of the National Academy of Sciences 118, n.º 1 (28 de diciembre de 2020): e2020205118. http://dx.doi.org/10.1073/pnas.2020205118.

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Performance of membranes for water purification is highly influenced by the interactions of solvated species with membrane surfaces, including surface adsorption of solutes upon fouling. Current efforts toward fouling-resistant membranes often pursue surface hydrophilization, frequently motivated by macroscopic measures of hydrophilicity, because hydrophobicity is thought to increase solute–surface affinity. While this heuristic has driven diverse membrane functionalization strategies, here we build on advances in the theory of hydrophobicity to critically examine the relevance of macroscopic characterizations of solute–surface affinity. Specifically, we use molecular simulations to quantify the affinities to model hydroxyl- and methyl-functionalized surfaces of small, chemically diverse, charge-neutral solutes represented in produced water. We show that surface affinities correlate poorly with two conventional measures of solute hydrophobicity, gas-phase water solubility and oil–water partitioning. Moreover, we find that all solutes show attraction to the hydrophobic surface and most to the hydrophilic one, in contrast to macroscopically based hydrophobicity heuristics. We explain these results by decomposing affinities into direct solute interaction energies (which dominate on hydroxyl surfaces) and water restructuring penalties (which dominate on methyl surfaces). Finally, we use an inverse design algorithm to show how heterogeneous surfaces, with multiple functional groups, can be patterned to manipulate solute affinity and selectivity. These findings, importantly based on a range of solute and surface chemistries, illustrate that conventional macroscopic hydrophobicity metrics can fail to predict solute–surface affinity, and that molecular-scale surface chemical patterning significantly influences affinity—suggesting design opportunities for water purification membranes and other engineered interfaces involving aqueous solute–surface interactions.

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2

Berg, M. M., K. J. Kim, R. L. Lubman y E. D. Crandall. "Hydrophilic solute transport across rat alveolar epithelium". Journal of Applied Physiology 66, n.º 5 (1 de mayo de 1989): 2320–27. http://dx.doi.org/10.1152/jappl.1989.66.5.2320.

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Diffusional fluxes of a series of hydrophilic nonelectrolytes (molecular radii ranging from 0.15 to 0.57 nm) were measured across the alveolocapillary barrier in the isolated perfused fluid-filled rat lung. Radiolabeled solutes were lavaged into the distal air spaces of isolated Ringer-perfused lungs, and apparent permeability-surface area products were calculated from the rates of isotope appearance in the recirculating perfusate. These data were used to estimate theoretical equivalent pore radii in the alveolar epithelium, with the assumption of diffusive flow through water-filled cylindrical pores. The alveolar epithelium is best characterized by two pore populations, with small pores (radius 0.5 nm) occupying 98.7% of total pore area and larger pores (radius 3.4 nm) occupying 1.3% of total pore area. Net water flow out of the alveolar space was measured by including an impermeant solute (dextran) in the lavage fluid and measuring its concentration in the alveolar space as a function of time. Under control conditions, net water flow averaged 167 nl/s. When 24 microM terbutaline was added to the perfusate, net water flow increased significantly to 350 nl/s (P less than 0.001). Terbutaline had no effect on the fluxes of either glycerol (which traverses the small pore pathway) or sucrose (which traverses the large pore pathway). These findings indicate that the intact mammalian alveolar epithelium is complex and highly resistant to the flow of solutes and water.

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3

Pandit, Bijan, Abhijit Sarkar y Biswajit Sinha. "Solution thermodynamics of sodium pyruvate in aqueous glycine solutions at T 298.15-313.15 K". Journal of the Serbian Chemical Society 81, n.º 11 (2016): 1283–94. http://dx.doi.org/10.2298/jsc151031034p.

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In this study we investigated the effects of sodium pyruvate on the solution thermodynamics of glycine in terms of the solute-solute and solute-solvent interactions in aqueous solutions. Measured density and viscosity were used to derive apparent molar volumes (?V), standard partial molar volumes (?V0) and viscosity B-coefficients at 298.15, 303.15 K, 308.15, and 318.15 K under ambient pressure. The interactions are further discussed in terms of ion-dipolar, hydrophobic- hydrophobic, hydrophilic-hydrophobic group interactions. The activation parameters of viscous flow were also discussed in terms of transition state theory. The overall results indicated that ion-hydrophilic and hydrophilic-hydrophilic group interactions are predominant in the ternary solutions.

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4

Sarkar, Abhijit y Biswajit Sinha. "Solution thermodynamics of aqueous nicotinic acid solutions in presence of tetrabutylammonium hydrogen sulphate". Journal of the Serbian Chemical Society 78, n.º 8 (2013): 1225–40. http://dx.doi.org/10.2298/jsc111212027s.

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In this study we investigated the effects of tetrabutylammonium hydrogen sulphate (Bu4NHSO4) on the solute-solute and solute-solvent interactions in the aqueous solutions of nicotinic acid in terms of apparent molar volumes (?V), standard partial molar volumes (?V0) and viscosity B-coefficients at 298.15, 308.15, and 318.15 K under ambient pressure. These interactions are further discussed in terms of ion-dipolar, hydrophobic- hydrophobic, hydrophilic-hydrophobic group interactions. The activation parameters of viscous flow for Bu4NHSO4 in the aqueous solutions of nicotinic acid were discussed in terms of transition state theory. The overall results indicated that ion-hydrophilic and hydrophilic-hydrophilic group interactions are predominant in the aqueous solutions of nicotinic acid and Bu4NHSO4 has a dehydration effect on the hydrated nicotinic acid.

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5

Kim, Yong Ho, Kwang-Jin Kim, David Z. D’Argenio y Edward D. Crandall. "Characteristics of Passive Solute Transport across Primary Rat Alveolar Epithelial Cell Monolayers". Membranes 11, n.º 5 (30 de abril de 2021): 331. http://dx.doi.org/10.3390/membranes11050331.

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Primary rat alveolar epithelial cell monolayers (RAECM) were grown without (type I cell-like phenotype, RAECM-I) or with (type II cell-like phenotype, RAECM-II) keratinocyte growth factor to assess passive transport of 11 hydrophilic solutes. We estimated apparent permeability (Papp) in the absence/presence of calcium chelator EGTA to determine the effects of perturbing tight junctions on “equivalent” pores. Papp across RAECM-I and -II in the absence of EGTA are similar and decrease as solute size increases. We modeled Papp of the hydrophilic solutes across RAECM-I/-II as taking place via heterogeneous populations of equivalent pores comprised of small (0.41/0.32 nm radius) and large (9.88/11.56 nm radius) pores, respectively. Total equivalent pore area is dominated by small equivalent pores (99.92–99.97%). The number of small and large equivalent pores in RAECM-I was 8.55 and 1.29 times greater, respectively, than those in RAECM-II. With EGTA, the large pore radius in RAECM-I/-II increased by 1.58/4.34 times and the small equivalent pore radius increased by 1.84/1.90 times, respectively. These results indicate that passive diffusion of hydrophilic solutes across an alveolar epithelium occurs via small and large equivalent pores, reflecting interactions of transmembrane proteins expressed in intercellular tight junctions of alveolar epithelial cells.

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6

Stulc, J. y B. Stulcova. "Asymmetrical transfer of inert hydrophilic solutes across rat placenta". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 265, n.º 3 (1 de septiembre de 1993): R670—R675. http://dx.doi.org/10.1152/ajpregu.1993.265.3.r670.

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Transfer of [14C]mannitol, 51Cr-labeled EDTA, and [14C]-inulin from mother to fetus and from fetus to mother was measured in rats under pentobarbital anesthesia. The clearance of the three substances from the mother to fetus (Kmf) was 2.69 +/- 0.38, 1.93 +/- 0.73, and 0.47 +/- 0.14 microliter/min (means +/- SE), respectively, and the clearance from fetus to mother (Kfm) was 5.97, 6.66, and 4.95 microliters/min, respectively (the SE could not be estimated). Kfm appears to be consistently higher than Kmf by an almost constant value of approximately 4 microliters/min. To explain this a hypothesis was proposed according to which volume flow circulates across the placenta. Solute-free water is driven transcellularly across the placental barrier from the maternal to the fetal side by a difference of osmotic pressure created by active transport of some solutes (mainly Na+) to the fetus. Water together with all solutes dissolved returns from fetus to mother by filtration through wide extracellular channels in the placenta down a hydrostatic pressure gradient.

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7

Brown, Daniel, You Han Bae y Sung Wan Kim. "Hydrophilic Solute Release from a Hydrophobic Elastic Matrix". Macromolecules 27, n.º 18 (agosto de 1994): 4952–59. http://dx.doi.org/10.1021/ma00096a016.

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8

Xu, Yang, Yingying Zhu, Zhen Chen, Jinyuan Zhu y Geng Chen. "A Comprehensive Review on Forward Osmosis Water Treatment: Recent Advances and Prospects of Membranes and Draw Solutes". International Journal of Environmental Research and Public Health 19, n.º 13 (5 de julio de 2022): 8215. http://dx.doi.org/10.3390/ijerph19138215.

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Forward osmosis (FO) is an evolving membrane separation technology for water treatment and reclamation. However, FO water treatment technology is limited by factors such as concentration polarization, membrane fouling, and reverse solute flux. Therefore, it is of a great importance to prepare an efficient high-density porous membrane and to select an appropriate draw solute to reduce concentration polarization, membrane fouling, and reverse solute flux. This review aims to present a thorough evaluation of the advancement of different draw solutes and membranes with their effects on FO performance. NaCl is still widely used in a large number of studies, and several general draw solutes, such as organic-based and inorganic-based, are selected based on their osmotic pressure and water solubility. The selection criteria for reusable solutes, such as heat-recovered gaseous draw, magnetic field-recovered MNPs, and electrically or thermally-responsive hydrogel are primarily based on their industrial efficiency and energy requirements. CA membranes are resistant to chlorine degradation and are hydrophilic, while TFC/TFN exhibit a high inhibition of bio-adhesion and hydrolysis. AQPs are emerging membranes, due to proteins with complete retention capacity. Moreover, the development of the hybrid system combining FO with other energy or water treatment technologies is crucial to the sustainability of FO.

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9

Briskin, Donald P. "Membranes and Transport Systems in Plants: An Overview". Weed Science 42, n.º 2 (junio de 1994): 255–62. http://dx.doi.org/10.1017/s0043174500080371.

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Membranes define the outer boundary of the living protoplast and the internal compartmentation of plant cells. From a structural point of view, membranes consist of a lipid bilayer and proteins essential for functions such as solute transport, signal transduction, and numerous metabolic reactions. While membranes can represent a significant barrier to the free movement of many solutes, those with sufficient lipid solubility may move across membranes by dissolving into the lipid bilayer. However, selective membrane transport is generally observed for hydrophilic solutes such as mineral nutrients and cell metabolites. Such selective transport requires an input of metabolic energy, and in plants this occurs via the production of proton electrochemical gradients across the membrane by substrate- (ex. ATP, PPi) driven proton pumps. Selective solute transport is then mediated by membrane-associated secondary transport systems which utilize the proton electrochemical gradient to drive the transport process. This review of membrane structure and transport system function provides a background for a further examination of herbicide interactions with plant membranes.

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10

MASON, G. R., A. M. PETERS, E. BAGDADES, M. J. MYERS, D. SNOOK y J. M. B. HUGHES. "Evaluation of pulmonary alveolar epithelial integrity by the detection of restriction to diffusion of hydrophilic solutes of different molecular sizes". Clinical Science 100, n.º 3 (25 de enero de 2001): 231–36. http://dx.doi.org/10.1042/cs1000231.

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The rate of transfer of a hydrophilic solute from the alveoli to pulmonary blood following inhalation as an aerosol depends on the molecular size of the solute and the permeability of the alveolar epithelium. The value of this measurement for assessing damage to the epithelium in lung disease is compromised by cigarette smoking, which accelerates clearance by unknown mechanisms. The rates of clearance of 99mTc-labelled diethylenetriaminepenta-acetic acid (DTPA) (molecular mass 492 Da) and 113mIn-labelled biotinylated DTPA (B-DTPA) (molecular mass 1215 Da) were monitored simultaneously by dynamic γ-radiation camera imaging following simultaneous inhalation, and compared between eight normal non-smoking subjects and nine habitual cigarette smokers. The clearance rates of DTPA were 0.95 (S.D. 0.39)%/min in non-smokers and 4.13 (1.06) %/min in smokers. These were about twice the clearance rates of B-DTPA, which in the corresponding groups were 0.41 (0.26) and 2.12 (0.72)%/min respectively. The ratio of the B-DTPA/DTPA clearance rates was, in all subjects, less than the ratio (0.74) of the cube roots of the molecular masses of the solutes, assumed to correspond to the ratio of their free diffusion coefficients in water, and was not significantly different between smokers and non-smokers. As alveolar permeability increased, the ratio of clearance rates in the entire population showed a significant trend to increase in a non-linear fashion towards the value corresponding to the ratio of the free diffusion coefficients. We conclude that the diffusion of at least the larger of these two solutes through the pulmonary alveolar epithelium is restricted (i.e. associated with a reflection coefficient greater than zero). Cigarette smoking, however, does not appear to cause a loss of this restriction, and may increase solute clearance by other mechanisms, such as reducing fluid volume within the alveolus, thereby raising the local radiotracer concentration, or increasing the number of pores available for solute exchange without affecting pore size. Conversely, if restriction was lost in lung disease, the ratio of the clearance rates of two solutes of dissimilar sizes could be used to detect disease in smokers as well as non-smokers.

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11

Lynden-Bell, R. M., J. C. Rasaiah y J. P. Noworyta. "Using simulation to study solvation in water". Pure and Applied Chemistry 73, n.º 11 (1 de enero de 2001): 1721–31. http://dx.doi.org/10.1351/pac200173111721.

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Simulations of simple solutes (charged and uncharged spheres) in model water have been performed in order to elucidate aspects of solvation in water at ambient and supercritical states. The variation of solvation entropy as a function of solute charge has been used to investigate hydrophobic and hydrophilic ordering and the structure-making and structure-breaking effects of ions. Simulations with model solvents, which differ from water in certain features, have been used to try to identify the particular properties of water that are associated with these phenomena.

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12

Schauer, Jan y Takaomi Kobayashi. "Salt Separation by Charged Membranes". Collection of Czechoslovak Chemical Communications 59, n.º 6 (1994): 1356–60. http://dx.doi.org/10.1135/cccc19941356.

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Two negatively charged membranes made from poly(acrylonitrile-co-sodium styrenesulfonate) having ion exchange capacity of 0.058 and 0.15 meq/g dry matter were tested in ultrafiltration of aqueous solutions of dextrans and low-molecular-weight electrolytes. The former membrane, though permeable to bulky dextrans (molecular weight cut-off approximately 500 000), fairly retained small electrolytes. The latter, extremely hydrophilic membrane showed little resistance to the feed solution and no retention of solutes was observed. The influence of the feed concentration, electrolyte type, and operating pressure on the solute retention was determined.

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13

Wallqvist, A. y D. G. Covell. "Cooperativity of Water-Solute Interactions at a Hydrophilic Surface". Journal of Physical Chemistry 99, n.º 15 (abril de 1995): 5705–12. http://dx.doi.org/10.1021/j100015a063.

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14

Weinbaum, S. "Interfacial Transport in Large and Small Blood Vessels". Applied Mechanics Reviews 43, n.º 5S (1 de mayo de 1990): S109—S118. http://dx.doi.org/10.1115/1.3120789.

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In this paper we shall review some recent mathematical models which have led to new conceptual views of the ultrastructural pathways by which water, solutes and large molecules cross the endothelial interface between tissue and blood. In particular, we shall show how a sequence of models for the endothelium and underlying tissue in large arteries have finally led to the experimental discovery of the large pore via which LDL and other large molecules enter the artery wall and how a new three-dimensional model for the interendothelial cleft in capillaries might reconcile the several long standing paradoxes relating to the measured filtration and solute permeability coefficients in the transcapillary exchange of water and hydrophilic solutes in the microcirculation.

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15

Rechthand, E., Q. R. Smith y S. I. Rapoport. "A compartmental analysis of solute transfer and exchange across blood-nerve barrier". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 255, n.º 2 (1 de agosto de 1988): R317—R325. http://dx.doi.org/10.1152/ajpregu.1988.255.2.r317.

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A three-compartment model was derived to analyze solute exchange among plasma, peripheral nerve epineurium, and endoneurium. The model was fit to measured tibial-nerve epineurial and endoneurial contents of [14C]sucrose after intravenous bolus injection of tracer in pentobarbital sodium-anesthetized rats. The transfer constant (K) for tracer at epineurial vessels approximated 1.1 X 10(-3) ml.s-1.g whole-nerve-1. K at the blood-nerve barrier (BNB) equaled 1.36-1.51 X 10(-5) ml.s-1.g endoneurium-1. The endoneurial uptake data were analyzed also by a simplified two-compartment model incorporating solute exchange between plasma and endoneurium. K at the BNB (1.46 X 10(-5) ml.s-1.g endoneurium-1), determined by multiple uptake time graphic analysis, was only threefold greater than K at the blood-brain barrier. The transfer constant at the perineurium alone was determined in situ and equaled (1 X 10(-6) ml.s-1.g endoneurium-1. Calculated permeability coefficients (X 10(-8) cm/s) equaled 3.2 at the perineurium, 23 at the endoneurial capillaries, and 3.2 at the brain vasculature. The results demonstrate that for hydrophilic nonelectrolytes 1) flux across the perineurium contributes significantly to solute uptake from plasma into the endoneurium; 2) although nerve capillaries are more permeable than brain capillaries, the tissues of the BNB function as a unit to markedly restrict solute diffusion into the endoneurium; and 3) a two-compartment analysis accurately describes hydrophilic solute transfer from plasma into peripheral nerve.

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16

Beierbeck, Helmut y Raymond U. Lemieux. "Computer simulation studies of the solvation of oligosaccharides". Canadian Journal of Chemistry 68, n.º 6 (1 de junio de 1990): 820–27. http://dx.doi.org/10.1139/v90-130.

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Computer simulations of the hydration of the tetrasaccharide αLFuc(1 → 2)βDGal(1 → 3) αLFuc(1 → 4) βDGlcNAc-OMe and one of its deoxy derivatives were carried out as a first step toward an understanding of the role of water in the recognition of oligosaccharides by proteins. The model consisted of one solute molecule in one of its low-energy conformations, surrounded by 250 water molecules. The solute–water and water–water interaction energies were evaluated with Clementi's potentials. Ensemble states for the derivation of average properties were generated by Monte Carlo methods. As expected, the strength of interaction between water and the amphiphilic solute was found to be considerably greater at hydrophilic than at hydrophobic sites. Furthermore, the average distance between the solvation shell and the solute surface was about 1 Å greater near hydrophobic than around hydrophilic groups. There is also a definitive alignment of the water dipole around the hydroxyl groups of the saccharide, which is not evident over the hydrophobic regions. Finally, in a parallel investigation the tetrasaccharides were solvated by adding water to the solute at sites of minimum energy of association, in order to explore less-CPU-time-consuming alternatives to Monte Carlo simulations. While the patterns of interaction energies, distances, and dipole orientations were found to be similar to Monte Carlo results, the time savings were not as significant as hoped. Keywords: Monte Carlo simulations, numerical solvation studies, solvation simulations of oligosaccharides, molecular recognition, carbohydrate solvation.

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17

Mahlangu, O. T., R. Nackaerts, B. B. Mamba y A. R. D. Verliefde. "Development of hydrophilic GO-ZnO/PES membranes for treatment of pharmaceutical wastewater". Water Science and Technology 76, n.º 3 (29 de marzo de 2017): 501–14. http://dx.doi.org/10.2166/wst.2017.194.

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Membrane application in water reclamation is challenged by fouling which deteriorates membrane performance in terms of permeate flux and solute rejection. Several studies focusing on antifouling membranes incorporated with nanoparticles have been carried out, but these membranes are not yet a viable solution due to their high energy requirements and inability to completely remove or degrade trace organic compounds (TOrCs). Therefore, this study aims at fabricating polyethersulfone (PES) membranes for treatment of pharmaceutical wastewater by using a unique membrane synthesis approach. PES membranes were synthesised by casting two different solutions before coagulation. Therefore, the synthesis technique was called ‘double-casting phase inversion’. The membranes were impregnated with nanohybrid graphene oxide-zinc oxide (GO-ZnO) to increase their hydrophilicity, rejection of pharmaceuticals (by decreasing membrane-solute hydrophobic interactions), resistance to organic fouling and photodegradation properties. The addition of GO-ZnO increased membrane hydrophilicity and pure water permeability. The rejection of TOrCs and anti-fouling properties were also improved due to a reduction in membrane-solute and membrane-foulant hydrophobic interactions, respectively. In addition to improved TOrC rejection properties and resistance to fouling, GO-ZnO/PES membranes degraded Brilliant Black.

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18

Bondesson, Eva, Thomas Bengtsson, Lars-Erik Nilsson y Per Wollmer. "Site of deposition and absorption of an inhaled hydrophilic solute". British Journal of Clinical Pharmacology 63, n.º 6 (junio de 2007): 722–31. http://dx.doi.org/10.1111/j.1365-2125.2006.02835.x.

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19

Wang, Jichao, Shanshan Gao, Jiayu Tian, Fuyi Cui y Wenxin Shi. "Recent Developments and Future Challenges of Hydrogels as Draw Solutes in Forward Osmosis Process". Water 12, n.º 3 (3 de marzo de 2020): 692. http://dx.doi.org/10.3390/w12030692.

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Forward osmosis (FO) has been recently regarded as a promising water treatment technology due to its lower energy consumption and lower membrane fouling propensity compared to the reverse osmosis (RO). The absence of suitable draw solute constraints the wide-range application of the FO. Hydrogels are three-dimensional hydrophilic polymer networks that can absorb a huge amount of water. Particularly, stimuli-responsive polymer hydrogels can undergo a reversible volume change or solution-gel phase transition in response to external environmental stimuli, including temperature, light, pressure, solvent composition, and pH. These intrinsic properties indicate the lowest regeneration cost of draw solutes compared to the thermal method and other membrane processes. This review aims to introduce the research progress on hydrogels as draw solutes, clarify the existing problems and point out the further research direction.

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Mishra, Tripti, Sudipta Ramola, Anil Kumar Shankhwar y R. K. Srivastava. "Use of synthesized hydrophilic magnetic nanoparticles (HMNPs) in forward osmosis for water reuse". Water Supply 16, n.º 1 (25 de agosto de 2015): 229–36. http://dx.doi.org/10.2166/ws.2015.131.

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Forward osmosis (FO) is attracting worldwide attention as an emerging technology in the fields of power generation, water reuse, desalination, pharmaceuticals and food processing. Still, the critical challenge of finding a suitable draw solute for FO persists. Therefore the current research focuses on synthesizing hydrophilic magnetic nanoparticles (HMNPs) and systematically investigating their potential as draw solutes. HMNPs were synthesized using functional groups polyethylene glycol (PEG 400) and polyacrylic acid (PAA). These functional groups under different ratios with a metal precursor react by one-pot polyol and thermal decomposition methods respectively to give different diameter HMNPs. In addition the effect of different sizes of synthesized HMNPs was investigated for their recovery under an external magnetic field and reusability in FO performance. The physical properties and chemical compositions of the resultant MNPs are fully characterized. Transmission electron microscopy (TEM) analyses show the characteristics as spherical morphology with a narrow size distribution, and a mean size from 9 to 32.5 nm for PEG and 8 to 30 nm for PAA coated HMNPs depending on the ratio of the functional group and metal precursor. The PEG and PAA layer on the MNPs is confirmed by Fourier transform infrared (FTIR) analysis, and thermogravimetric analysis demonstrates a hydrophilic surface composition. The PEG and PAA coated HMNPs generate high osmotic pressures and exhibit good dispersibility in aqueous solutions. Water fluxes of >13 L m−2 h−1 are achieved across Hydration Technologies Inc. flat sheet membranes at a concentration of 0.05 M of HMNPs using deionized water as the feed solution. The HMNPs can be easily recaptured from draw solutions by applying an external magnetic field and recycling them back as draw solute in the FO process. The MNPs remain active after nine runs of recycling but with a total water flux decrease of 5% in PEG and 3% with each successive recycling due to slight aggregation, and reduced surface to volume ratio is observed. Results of the present study have demonstrated that PEG and PAA coated HMNPs can viewed as promising and potential draw solutes in the FO process.

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21

Sterkers, O., E. Ferrary, G. Saumon y C. Amiel. "Na and nonelectrolyte entry into inner ear fluids of the rat". American Journal of Physiology-Renal Physiology 253, n.º 1 (1 de julio de 1987): F50—F58. http://dx.doi.org/10.1152/ajprenal.1987.253.1.f50.

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Kinetics of hydrophilic solute entry into endolymph (EL), perilymph (PL), and cerebrospinal fluid (CSF) were studied after intravenous administration (sodium, urea, glycerol, mannitol, sucrose) and cerebral lateral ventricle injection (urea, sucrose) of tracers in anesthetized rats. Samples of cochlear EL, PL of scala vestibuli (PLV), PL of scala tympani (PLT), and cisternal CSF were obtained. The data showed slow entry of tracers in PLV, PLT, and CSF as follows: Na greater than urea greater than mannitol approximately sucrose; slower entry of mannitol and sucrose in PLT and CSF than in PLV; 1 h delayed peak of radioactivity in PLV compared with the immediate peaks in PLT and CSF after CSF injection, and the value of PLV peak was 13% that in CSF; extremely slow entry of nonelectrolytes in EL. These results indicate that PLV originates mainly from plasma across a blood-perilymph barrier that restricts the entry of small hydrophilic solutes. The blood-perilymph barrier is most likely composed of an endothelial barrier associated with an epithelial secretion. The latter could be located at the vasculo-epithelial zone of the spiral limbus.

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22

Zakerhamidi, M. S. y A. Karimi. "Hydrophilic gel composition effect on the molecular association and spectroscopic behavior of rhodamine B". Canadian Journal of Chemistry 90, n.º 9 (septiembre de 2012): 776–83. http://dx.doi.org/10.1139/v2012-055.

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Electronic absorption spectra of rhodamine B dye in aqueous solutions and in a polyacrylamide hydrogel matrix with different structural compositions were studied at room temperature. The transport and the solute–solute interactions of rhodamine B in aqueous solutions across the hydrophilic gels were investigated via exploration of the spectral properties of the dye-loaded hydrogel. The nature of the dye pair interactions in these media was discussed using the Kasha exciton theory. In addition, the monomer–dimer equilibrium of rhodamine B molecules in hydrogels with different compositional percentages was studied by means of UV–vis spectroscopy and least-squares fitting methods.

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23

Shinto, Hiroyuki, Shintaro Morisada y Ko Higashitani. "Potentials of Mean Force for Hydrophilic–Hydrophobic Solute Pairs in Water". JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 38, n.º 7 (2005): 465–77. http://dx.doi.org/10.1252/jcej.38.465.

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Matsuda, Kazuki, Tenshin Oyama, Hirotaka Ishizuka, Shuji Hironaka y Jun Fukai. "Effect of Marangoni Convection in a Droplet Containing Surfactant on Thin Film Shape". MATEC Web of Conferences 333 (2021): 03002. http://dx.doi.org/10.1051/matecconf/202133303002.

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In printed electronics, uniform and solute film formation by the inkjet method is very important. This study aims to clarify the relationship between Marangoni convection generated by adding surfactant and thinning of solute film. First, four types of surfactants were added one by one to the anisole-polystyrene solution with varying concentrations, and then a little amount of fluorescent polymer was added as tracer to each solution. Next, each solution was dropped on a hydrophilic substrate with a droplet diameter of 80 micrometers using an inkjet method, and the flow in the evaporation process and the shape of the solute film after drying were observed. As a result, Marangoni convection occurred when any surfactant was added at a certain concentration or more, and the solute film after drying of the droplets to which two kinds of surfactants were added became thin and approached a uniform shape. In addition, the measurement of surface tension showed that the visualized flow is the Marangoni convection.

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25

Matsuda, Kazuki, Tenshin Oyama, Hirotaka Ishizuka, Shuji Hironaka y Jun Fukai. "Effect of Marangoni Convection in a Droplet Containing Surfactant on Thin Film Shape". MATEC Web of Conferences 333 (2021): 03002. http://dx.doi.org/10.1051/matecconf/202133303002.

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In printed electronics, uniform and solute film formation by the inkjet method is very important. This study aims to clarify the relationship between Marangoni convection generated by adding surfactant and thinning of solute film. First, four types of surfactants were added one by one to the anisole-polystyrene solution with varying concentrations, and then a little amount of fluorescent polymer was added as tracer to each solution. Next, each solution was dropped on a hydrophilic substrate with a droplet diameter of 80 micrometers using an inkjet method, and the flow in the evaporation process and the shape of the solute film after drying were observed. As a result, Marangoni convection occurred when any surfactant was added at a certain concentration or more, and the solute film after drying of the droplets to which two kinds of surfactants were added became thin and approached a uniform shape. In addition, the measurement of surface tension showed that the visualized flow is the Marangoni convection.

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26

Suresh Babu P, Marina Amarendra, Subha V J y Senthamarai S. "An analytical assessment on Mucoadhesive Buccal Drug Delivery System for improving patient convenience and compliance". International Journal of Research in Pharmaceutical Sciences 11, SPL4 (20 de diciembre de 2020): 252–58. http://dx.doi.org/10.26452/ijrps.v11ispl4.3780.

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In recent years, the novel mucoadhesive buccal drug delivery system has been developed over the conventional and systemic dosage forms. To bypass drugs from the hepatic first-pass metabolism and it enhances the bioavailability of drug at the site of administration. Absorption of a drug through the buccal mucosa reduces the degradation. Some of the enzyme activity and pH variation in the gastrointestinal tract reduces the absorption and active drug loss. To overcome this problem, the buccal route is preferred. Polymers are used in this formulation to improve the drug release rate over an extended period, and also, the therapeutic plasma level of the drug can be rapidly achieved. Overall this narrative review explains mechanism and theories, method of preparation, factors affecting mucoadhesion, advantages and limitations, applications, components used in the formulation, characterization and evaluation methods. Since the cytoplasm and intercellular spaces are hydrophilic. Lipophilic drugs have a low solubility in this environment. However, the cell membrane is rather lipophilic; it tends to difficulty permeating the hydrophilic solute through the cell membrane because of a low partition coefficient. Therefore, the cytoplasm and intercellular spaces act as a major barrier to penetration of lipophilic compounds and the cell membrane poses as an extensive transport barrier for hydrophilic compounds. Since the oral epithelial is stratified, the permeation of solute may involve these combination routes so that the route is more predictable.

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27

Otitoju, Tunmise Ayode, Abdul Latif Ahmad y Boon Seng Ooi. "Recent advances in hydrophilic modification and performance of polyethersulfone (PES) membrane via additive blending". RSC Advances 8, n.º 40 (2018): 22710–28. http://dx.doi.org/10.1039/c8ra03296c.

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The blending of additives in the polyethersulfone (PES) matrix is an important approach in the membrane industry to reduce membrane hydrophobicity and improve the performance (flux, solute rejection, and reduction of fouling).

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28

Brazel, Christopher S. y Nikolaos A. Peppas. "Mechanisms of solute and drug transport in relaxing, swellable, hydrophilic glassy polymers". Polymer 40, n.º 12 (junio de 1999): 3383–98. http://dx.doi.org/10.1016/s0032-3861(98)00546-1.

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29

Delgado-Charro, M. Begoña, Graciela Iglesias-Vilas, José Blanco-Méndez, M. Arturo López-Quintela, Jean-Paul Marty y Richard H. Guy. "Delivery of a hydrophilic solute through the skin from novel microemulsion systems". European Journal of Pharmaceutics and Biopharmaceutics 43, n.º 1 (enero de 1997): 37–42. http://dx.doi.org/10.1016/s0939-6411(96)00016-1.

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30

Madara, J. L., S. Carlson y J. M. Anderson. "ZO-1 maintains its spatial distribution but dissociates from junctional fibrils during tight junction regulation". American Journal of Physiology-Cell Physiology 264, n.º 5 (1 de mayo de 1993): C1096—C1101. http://dx.doi.org/10.1152/ajpcell.1993.264.5.c1096.

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Tight junctions restrict diffusion of hydrophilic solutes through the paracellular pathways of columnar epithelia. It is now apparent that the barrier function of tight junctions is physiologically regulated. Current models of the tight junction envisage junctional subunits consisting of extracellular "kisses" between plasma membranes of adjacent cells, intramembrane components represented by freeze-fracture fibrils, and cytoplasmic elements of the cytoskeleton. Insights into functional relationships between these various components of tight junctions should be provided by mapping component interrelationships in states of altered junctional permeability. Here we define the spatial distribution of ZO-1 during a state of physiological regulation of intestinal absorptive cell tight junctions. Enhanced permeation of absorptive cell junctions in response to activation of apical membrane Na(+)-solute cotransporters does not lead to redistribution of the ZO-1 pool, as judged from quantitative ultrastructural immunolocalization studies employing two different ZO-1 antibodies. Surprisingly, ZO-1, which normally localizes under junctional kisses/fibrils, focally persists at sites where junctional kisses/fibrils are cleared. These findings suggest that 1) spatial redistribution of ZO-1 does not contribute to physiological regulation of junctions elicited by activation of Na(+)-solute cotransport and 2) ZO-1 and junctional fibrils may spatially dissociate during such regulated states.

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31

Salzman, A. L., H. Wang, P. S. Wollert, T. J. Vandermeer, C. C. Compton, A. G. Denenberg y M. P. Fink. "Endotoxin-induced ileal mucosal hyperpermeability in pigs: role of tissue acidosis". American Journal of Physiology-Gastrointestinal and Liver Physiology 266, n.º 4 (1 de abril de 1994): G633—G646. http://dx.doi.org/10.1152/ajpgi.1994.266.4.g633.

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Administration of lipopolysaccharide (LPS) to experimental animals leads to diminished mesenteric perfusion, increased ileal mucosal [H+] , and increased gut epithelial permeability to hydrophilic solutes. We sought to determine whether these phenomena are causally related. Experiments were performed in anesthetized pigs. Permeability was assessed by measuring the plasma-to-lumen clearance of fluorescein isothiocyanate dextran (4,000 Da; FD-4) by a segment of ileum perfused with Ringer lactate solution. Mucosal perfusion (Qmuc) and [H4+] were estimated using laser-Doppler flowmetry and tonometry, respectively. In an initial series of experiments, we showed that mucosal permeability was linearly correlated with mucosal [H+] in animals subjected to graded degrees of mechanically induced mesenteric ischemia (n = 14, R2 = 0.58, P < 0.002) or injected with graded doses of LPS (n = 11, R2 = 0.93, P < 0.0001). In a second series of experiments, we induced mucosal acidosis in normal pigs by mechanical ventilation with either a hypoxic (n = 7) or a hypercapnic (n = 5) gas mixture. In both groups, ileal mucosal permeability to FD-4 increased significantly (P < 0.05), although transmesenteric release of lactate increased significantly only in the hypoxic group. Qmuc was unchanged in both groups. These data suggest that mucosal acidosis, even in the absence of tissue ischemia or hypoxia, increases intestinal permeability to a macromolecular hydrophilic solute. Tissue acidosis may be an important factor contributing to LPS-induced gut mucosal hyperpermeability.

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32

Lupi, Laura, Brenda Bracco, Paola Sassi, Silvia Corezzi, Assunta Morresi, Daniele Fioretto, Lucia Comez y Marco Paolantoni. "Hydration Dynamics of Model Peptides with Different Hydrophobic Character". Life 12, n.º 4 (12 de abril de 2022): 572. http://dx.doi.org/10.3390/life12040572.

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The multi-scale dynamics of aqueous solutions of the hydrophilic peptide N-acetyl-glycine-methylamide (NAGMA) have been investigated through extended frequency-range depolarized light scattering (EDLS), which enables the broad-band detection of collective polarizability anisotropy fluctuations. The results have been compared to those obtained for N-acetyl-leucinemethylamide (NALMA), an amphiphilic peptide which shares with NAGMA the same polar backbone, but also contains an apolar group. Our study indicates that the two model peptides induce similar effects on the fast translational dynamics of surrounding water. Both systems slow down the mobility of solvating water molecules by a factor 6–8, with respect to the bulk. Moreover, the two peptides cause a comparable far-reaching spatial perturbation extending to more than two hydration layers in diluted conditions. The observed concentration dependence of the hydration number is explained considering the random superposition of different hydration shells, while no indication of solute aggregation phenomena has been found. The results indicate that the effect on the dynamics of water solvating the amphiphilic peptide is dominated by the hydrophilic backbone. The minor impact of the hydrophobic moiety on hydration features is consistent with structural findings derived by Fourier transform infrared (FTIR) measurements, performed in attenuated total reflectance (ATR) configuration. Additionally, we give evidence that, for both systems, the relaxation mode in the GHz frequency range probed by EDLS is related to solute rotational dynamics. The rotation of NALMA occurs at higher timescales, with respect to the rotation of NAGMA; both processes are significantly slower than the structural dynamics of hydration water, suggesting that solute and solvent motions are uncoupled. Finally, our results do not indicate the presence of super-slow water (relaxation times in the order of tens of picoseconds) around the peptides investigated.

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33

Panou, Athanasia I., Nikolaos Mantes, Kyriaki G. Papadokostaki y Merope Sanopoulou. "Solute permeability of elastomeric films containing dispersed swellable hydrophilic particles: A composite material approach". European Polymer Journal 93 (agosto de 2017): 471–79. http://dx.doi.org/10.1016/j.eurpolymj.2017.06.027.

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34

Harland, Ronald S. y Nikolaos A. Peppas. "Hydrophilic/hydrophobic, block and graft copolymeric hydrogels: synthesis, characterization, and solute partition and penetration". Journal of Controlled Release 26, n.º 3 (septiembre de 1993): 157–74. http://dx.doi.org/10.1016/0168-3659(93)90184-7.

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35

Almrhag, Omar, Paul George, Anna Bannikova, Lita Katopo y Stefan Kasapis. "Networks of polysaccharides with hydrophilic and hydrophobic characteristics in the presence of co-solute". International Journal of Biological Macromolecules 51, n.º 1-2 (julio de 2012): 138–45. http://dx.doi.org/10.1016/j.ijbiomac.2012.04.015.

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36

Fukuhara, Daiki, Satoru G. Itoh y Hisashi Okumura. "Replica permutation with solute tempering for molecular dynamics simulation and its application to the dimerization of amyloid-β fragments". Journal of Chemical Physics 156, n.º 8 (28 de febrero de 2022): 084109. http://dx.doi.org/10.1063/5.0081686.

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We propose the replica permutation with solute tempering (RPST) by combining the replica-permutation method (RPM) and the replica exchange with solute tempering (REST). Temperature permutations are performed among more than two replicas in RPM, whereas temperature exchanges are performed between two replicas in the replica-exchange method (REM). The temperature transition in RPM occurs more efficiently than in REM. In REST, only the temperatures of the solute region, the solute temperatures, are exchanged to reduce the number of replicas compared to REM. Therefore, RPST is expected to be an improved method taking advantage of these methods. For comparison, we applied RPST, REST, RPM, and REM to two amyloid-β(16–22) peptides in explicit water. We calculated the transition ratio and the number of tunneling events in the temperature space and the number of dimerization events of amyloid-β(16–22) peptides. The results indicate that, in RPST, the number of replicas necessary for frequent random walks in the temperature and conformational spaces is reduced compared to the other three methods. In addition, we focused on the dimerization process of amyloid-β(16–22) peptides. The RPST simulation with a relatively small number of replicas shows that the two amyloid-β(16–22) peptides form the intermolecular antiparallel β-bridges due to the hydrophilic side-chain contact between Lys and Glu and hydrophobic side-chain contact between Leu, Val, and Phe, which stabilizes the dimer of the peptides.

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37

Quiñones-Bolaños, Edgar, Hongde Zhou, Ranganathan Soundararajan y Lambert Otten. "Water and solute transport in pervaporation hydrophilic membranes to reclaim contaminated water for micro-irrigation". Journal of Membrane Science 252, n.º 1-2 (abril de 2005): 19–28. http://dx.doi.org/10.1016/j.memsci.2004.10.038.

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38

Park, Sung Yong, Hyo-Won Ahn, Jae Woo Chung y Seung-Yeop Kwak. "Magnetic core-hydrophilic shell nanosphere as stability-enhanced draw solute for forward osmosis (FO) application". Desalination 397 (noviembre de 2016): 22–29. http://dx.doi.org/10.1016/j.desal.2016.06.017.

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39

Byron, Peter R. y Richard N. Dalby. "Effects of Heat Treatment on the Permeability of Polyvinyl Alcohol Films to a Hydrophilic Solute". Journal of Pharmaceutical Sciences 76, n.º 1 (enero de 1987): 65–67. http://dx.doi.org/10.1002/jps.2600760118.

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40

Bao, Xiaoyong, Guillermo A. Altenberg y Luis Reuss. "Mechanism of regulation of the gap junction protein connexin 43 by protein kinase C-mediated phosphorylation". American Journal of Physiology-Cell Physiology 286, n.º 3 (marzo de 2004): C647—C654. http://dx.doi.org/10.1152/ajpcell.00295.2003.

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Phosphorylation of the gap junction protein connexin 43 (Cx43) by protein kinase C (PKC) decreases dye coupling in many cell types. We report an investigation of the regulation by PKC of Cx43 gap junctional hemichannels (GJH) expressed in Xenopus laevis oocytes. The activity of GJH was assessed from the uptake of hydrophilic fluorescent probes. PKC inhibitors increased probe uptake in isolated oocytes expressing recombinant Cx43, indicating that the regulatory effect occurs at the hemichannel level. We identified by mutational analysis the carboxy-terminal (CT) domain sequences involved in this response. We found that 1) Ser368 is responsible for the regulation of Cx43 GJH solute permeability by PKC-mediated phosphorylation, 2) CT domain residues 253-270 and 288-359 are not necessary for the effect of PKC, and 3) the prolinerich CT region is not involved in the effect of phosphorylation by PKC. Our results demonstrate that Ser368 (but not Ser372) is involved in the regulation of Cx43 solute permeability by PKC-mediated phosphorylation, and we conclude that different molecular mechanisms underlie the regulation of Cx43 by intracellular pH and PKC-mediated phosphorylation.

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41

Schmidt, Martin, Stefan Zahn, Florian Gehlhaar, Andrea Prager, Jan Griebel, Axel Kahnt, Wolfgang Knolle, Robert Konieczny, Roger Gläser y Agnes Schulze. "Radiation-Induced Graft Immobilization (RIGI): Covalent Binding of Non-Vinyl Compounds on Polymer Membranes". Polymers 13, n.º 11 (2 de junio de 2021): 1849. http://dx.doi.org/10.3390/polym13111849.

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Radiation-induced graft immobilization (RIGI) is a novel method for the covalent binding of substances on polymeric materials without the use of additional chemicals. In contrast to the well-known radiation-induced graft polymerization (RIGP), RIGI can use non-vinyl compounds such as small and large functional molecules, hydrophilic polymers, or even enzymes. In a one-step electron-beam-based process, immobilization can be performed in a clean, fast, and continuous operation mode, as required for industrial applications. This study proposes a reaction mechanism using polyvinylidene fluoride (PVDF) and two small model molecules, glycine and taurine, in aqueous solution. Covalent coupling of single molecules is achieved by radical recombination and alkene addition reactions, with water radiolysis playing a crucial role in the formation of reactive solute species. Hydroxyl radicals contribute mainly to the immobilization, while solvated electrons and hydrogen radicals play a minor role. Release of fluoride is mainly induced by direct ionization of the polymer and supported by water. Hydrophobic chains attached to cations appear to enhance the covalent attachment of solutes to the polymer surface. Computational work is complemented by experimental studies, including X-ray photoelectron spectroscopy (XPS) and fluoride high-performance ion chromatography (HPIC).

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42

Arahman, Nasrul, Afrilia Fahrina, Mukramah Yusuf Wahab y Umi Fathanah. "Morphology and performance of polyvinyl chloride membrane modified with Pluronic F127". F1000Research 7 (12 de junio de 2018): 726. http://dx.doi.org/10.12688/f1000research.15077.1.

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Background: Attempts to modify the morphology of membrane for application in industrial separation are being undertaken by many researchers. The present study discusses the morphological modification of polyvinyl chloride (PVC) membrane by combining the hydrophilic surfactant Pluronic F127 (PF127) in a polymer solution to improve the performance of the membrane. Method: The membrane is formed using the non-solvent induced-phase separation (NIPS) method. PF127 is added to the membrane solution as a membrane modifying agent. The effects of the surfactant concentration in the dope solution on the permeability of pure water, solute rejection, hydrophilic characteristics, and membrane morphology are investigated. Results: Higher concentrations of PF127 had a significant effect on the permeability of pure water. The highest membrane permeation was 45.65 l/m2.hr.atm with the addition of 7% PF127 additive. Conclusion: PF127 is successfully proposed as a membrane pore-forming agent in this work; the blending of this additive in appropriate amounts in the polymer solution is adequate to improve the performance of the PVC membrane.

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43

Arahman, Nasrul, Afrilia Fahrina, Mukramah Yusuf Wahab y Umi Fathanah. "Morphology and performance of polyvinyl chloride membrane modified with Pluronic F127". F1000Research 7 (10 de julio de 2018): 726. http://dx.doi.org/10.12688/f1000research.15077.2.

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Background: Attempts to modify the morphology of membrane for application in industrial separation are being undertaken by many researchers. The present study discusses the morphological modification of polyvinyl chloride (PVC) membrane by combining the hydrophilic surfactant Pluronic F127 (PF127) in a polymer solution to improve the performance of the membrane. Method: The membrane is formed using the non-solvent induced-phase separation (NIPS) method. PF127 is added to the membrane solution as a membrane modifying agent. The effects of the surfactant concentration in the dope solution on the permeability of pure water, solute rejection, hydrophilic characteristics, and membrane morphology are investigated. Results: Higher concentrations of PF127 had a significant effect on the permeability of pure water. The highest membrane permeation was 45.65 l/m2.hr.atm with the addition of 7% PF127 additive. Conclusion: PF127 is successfully proposed as a membrane pore-forming agent in this work; the blending of this additive in appropriate amounts in the polymer solution is adequate to improve the performance of the PVC membrane.

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44

Evans, Myfanwy E. y Roland Roth. "Solvation of a sponge-like geometry". Pure and Applied Chemistry 86, n.º 2 (1 de febrero de 2014): 173–79. http://dx.doi.org/10.1515/pac-2014-5027.

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Abstract Periodic entanglements of filaments and networks, which resemble sponge-like materials, are often found as self-assembled materials. The interaction between the geometry of the assembly and a solvent in its interstices can dictate the geometric configuration of the structure as well as influence macroscopic properties such as swelling and mechanics. In this paper, we show the calculation of the solvation free energy as a function of the solute–solvent interaction from hydrophilic to hydrophobic, for a candidate entanglement of filaments. We do this using the morphometric approach to solvation free energy, a method that disentangles geometric properties from thermodynamic coefficients, which we compute via density functional theory.

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45

Taraji, Maryam, Paul R. Haddad, Ruth I. J. Amos, Mohammad Talebi, Roman Szucs, John W. Dolan y Christopher A. Pohl. "Prediction of retention in hydrophilic interaction liquid chromatography using solute molecular descriptors based on chemical structures". Journal of Chromatography A 1486 (febrero de 2017): 59–67. http://dx.doi.org/10.1016/j.chroma.2016.12.025.

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46

Sahebi, Soleyman, Mohammad Kahrizi, Nasim Fadaie, Soheil Hadadpour, Bahman Ramavandi y Ralph Rolly Gonzales. "Developing a Thin Film Composite Membrane with Hydrophilic Sulfonated Substrate on Nonwoven Backing Fabric Support for Forward Osmosis". Membranes 11, n.º 11 (25 de octubre de 2021): 813. http://dx.doi.org/10.3390/membranes11110813.

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This study describes the fabrication of sulfonated polyethersulfone (SPES) as a super-hydrophilic substrate for developing a composite forward osmosis (FO) membrane on a nonwoven backing fabric support. SPES was prepared through an indirect sulfonation procedure and then blended with PES at a certain ratio. Applying SPES as the substrate affected membrane properties, such as porosity, total thickness, morphology, and hydrophilicity. The PES-based FO membrane with a finger-like structure had lower performance in comparison with the SPES based FO membrane having a sponge-like structure. The finger-like morphology changed to a sponge-like morphology with the increase in the SPES concentration. The FO membrane based on a more hydrophilic substrate via sulfonation had a sponge morphology and showed better water flux results. Water flux of 26.1 L m−2 h−1 and specific reverse solute flux of 0.66 g L−1 were attained at a SPES blend ratio of 50 wt % when 3 M NaCl was used as the draw solution and DI water as feed solution under the FO mode. This work offers significant insights into understanding the factors affecting FO membrane performance, such as porosity and functionality.

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47

McCalley, David V. "Effect of mobile phase additives on solute retention at low aqueous pH in hydrophilic interaction liquid chromatography". Journal of Chromatography A 1483 (febrero de 2017): 71–79. http://dx.doi.org/10.1016/j.chroma.2016.12.035.

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48

Chediack, J. G., E. Caviedes-Vidal, W. H. Karasov y M. Pestchanker. "Passive absorption of hydrophilic carbohydrate probes by the house sparrow Passer domesticus". Journal of Experimental Biology 204, n.º 4 (15 de febrero de 2001): 723–31. http://dx.doi.org/10.1242/jeb.204.4.723.

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To evaluate the permeability of the intestine of the house sparrow Passer domesticus to hydrophilic compounds, we applied a pharmacokinetic technique to measure in vivo absorption of two carbohydrate probes, l-arabinose and d-mannitol. Probes were fed or injected, and blood and excreta were subsequently collected and analyzed by gas chromatography/mass spectrometry. Following injection, plasma probe concentration decreased in a log-linear fashion, implying single-compartment, first-order kinetics. Following oral administration, plasma probe concentrations increased, reached a maximum at 10 min and then decreased in log-linear fashion. Mannitol and arabinose absorption were calculated from the areas under the post-absorption plasma curve and the respective distribution spaces and elimination constants. The amounts absorbed increased linearly with the concentration administered (range 1–1000 mmol × l(−1)), implying a passive process. The mouth-to-cloaca retention time of digesta, measured using the non-absorbable compound potassium ferrocyanide, was independent of probe concentration. On average, 69% of the oral dose of probe was absorbed and this was independent of the concentration of probe administered. This paper supports an earlier report of substantial passive glucose absorption in house sparrows and offers a method to study the extent of hydrophilic solute absorption, which has importance for future research in areas as diverse as biomedical, ecological and evolutionary physiology.

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Kunte, H. Jörg, Rebecca A. Crane, Doreen E. Culham, Deborah Richmond y Janet M. Wood. "Protein ProQ Influences Osmotic Activation of Compatible Solute Transporter ProP in Escherichia coliK-12". Journal of Bacteriology 181, n.º 5 (1 de marzo de 1999): 1537–43. http://dx.doi.org/10.1128/jb.181.5.1537-1543.1999.

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ABSTRACT ProP is an osmoregulatory compatible solute transporter inEscherichia coli K-12. MutationproQ220::Tn5 decreased the rate constant for and the extent of ProP activation by an osmotic upshift but did not alter proP transcription or the ProP protein level. Allele proQ220::Tn5 was isolated, and the proQ sequence was determined. LocusproQ is upstream from prc (tsp) at 41.2 centisomes on the genetic map. TheproQ220::Tn5 and prcphenotypes were different, however. Gene proQ is predicted to encode a 232-amino-acid, basic, hydrophilic protein (molecular mass, 25,876 Da; calculated isoelectric point, 9.66; 32% D, E, R, or K; 54.5% polar amino acids). The insertion of PCR-amplifiedproQ into vector pBAD24 produced a plasmid containing the wild-type proQ open reading frame, the expression of which yielded a soluble protein with an apparent molecular mass of 30 kDa. Antibodies raised against the overexpressed ProQ protein detected cross-reactive material in proQ + bacteria but not in proQ220::Tn5 bacteria. ProQ may be a structural element that influences the osmotic activation of ProP at a posttranslational level.

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50

Bey, Romain, Benoit Coasne y Cyril Picard. "Carbon dioxide as a line active agent: Its impact on line tension and nucleation rate". Proceedings of the National Academy of Sciences 118, n.º 33 (12 de agosto de 2021): e2102449118. http://dx.doi.org/10.1073/pnas.2102449118.

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By considering a water capillary bridge confined between two flat surfaces, we investigate the thermodynamics of the triple line delimiting this solid–liquid–vapor system when supplemented in carbon dioxide. In more detail, by means of atom-scale simulations, we show that carbon dioxide accumulates at the solid walls and, preferably, at the triple lines where it plays the role of a line active agent. The line tension of the triple line, which is quantitatively assessed using an original mechanical route, is shown to be driven by the line excess concentrations of the solute (carbon dioxide) and solvent (water). Solute accumulation at the lines decreases the negative line tension (i.e., more negative) while solvent depletion from the lines has the opposite effect. Such an unprecedented quantitative assessment of gas-induced line tension modifications shows that the absolute value of the negative line tension increases upon increasing the carbon dioxide partial pressure. As a striking example, for hydrophilic surfaces, the line tension is found to increase by more than an order of magnitude when the carbon dioxide pressure exceeds 3 MPa. By considering the coupling between line and surface effects induced by gaseous adsorption, we hypothesize from the observed gas concentration-dependent line tension a nontrivial impact on heterogeneous nucleation of nanometric critical nuclei.

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