• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.771-777
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• 1999

The structural function of three egg membrane layers and cuticle layer, and the effectiveness of 5 film coatings (chitosan, starch, gelatin, dextrin, mineral oil) on the prevention of Salmonella enteritidis penetration was investigated using confocal scanning laser microscopy (CSLM). Diameters of outer membrane fibers, inner membrane fibers and limiting membrane particles in eggshell were $1.5{\sim}7.2$, $0.8{\sim}2.0$ and $0.1{\sim}1.4\;{\mu}m$, respectively and average thicknesses were 10.0, 3.5, $3.6\;{\mu}m$, respectively. Average thickness of cuticle layer was $6.0\;{\mu}m$ and cuticle layer covered $40{\sim}80%$ of total eggshell surface. Average coating films thickness for chitosan, starch, gelatin, dextrin and mineral oil were 2.2, 2.5, 3.9, 3.6 and $5.0\;{\mu}m$, respectively. After immersion process eggshell surface was almost completely covered by coating films. Chitosan coating was most effective among 5 film coatings in inhibiting growth of Salmonella enteritidis. Penetration process of Salmonella enteritidis through eggshell was investigated by multicolor imaging using CSLM and plate counting. Cuticle layer was the most important structure in blocking the penetration. Among 5 film coatings, chitosan showed the best and similar effectiveness with cuticle layer.

• Membrane Journal
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• v.33 no.1
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• pp.1-12
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• 2023

In this review, surface modification methods of hydrophobic poly(tetrafluoroethylene) (PTFE) membrane are introduced and their improved hydrophilicity results are discussed. Fluoropolymer based membranes, represented by PTFE membranes have been used in various membrane separation processes, including membrane distillation, oil separation and gas separation. However, despite excellent physical properties such as chemical resistance, heat resistance and high mechanical strength, the strong hydrophobicity of PTFE membrane surface has become a challenging factor in expanding its membrane separation application. To improve the separation performance of PTFE membranes, wet chemical, hydrophilic coating, plasma, irradiation and atomic layer deposition are applied, modifying the surface property of PTFE membranes while maintaining their inherent properties.

• Membrane Journal
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• v.10 no.3
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• pp.130-138
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• 2000

Polyethersulfone (PES) asymmetric membranes for gas separation were prepared by dry/wet phase inversion method and their separation properties for CO$_2$ and N$_2$ gases were investigated. The effects of important variables such as composition of casting solution and evaporation time in preparation of asymmetric gas membrane on membrane morphology and the separation properties were analyzed and the optimum condition of membrane preparation was established. To compensate the defects like pinholes existed on skin layer of the membrane prepared, the membranes were coated with silicone resin. By comparing separation properties after coating with those before coating, we found that the coating of silicone resin was effective to enhance the separation properties. The casting solution mainly used in this study consisted of PES, N-methyl-2-pyrrolidone, acetone, ethanol and distilled water was used as coagulation agent. It was shown that the selectivity for CO$_2$/N$_2$ was getting higher but the permeability decreases, as the contents of PES and volatile organic solvent and evaporation time increased. The selectivity for CO$_2$/N$_2$ and permeability of CO$_2$ of the membrane prepared under the optimum condition were found to be 61 and 21 GPU, respectively.

• Membrane Journal
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• v.6 no.3
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• pp.182-187
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• 1996

Hydrophilic poly(acrylonitrile) [PAN] membrane with good molecular weight cut-off characteristics were prepared by using the phase inversion method. Permeability and molecular weight cut-off of the membranes were measured through the ultrafiltration test. On the surface of the PAN support membranes, poly(acrylic acid) [PAA] was deposited by dip-coating. The water permeability of the PAN support membrane had $0.17~31\textrm{mm}^3/m^{2} \cdot s \cdot Pa$, the molecular weight cut-off 42, 000~150, 000. The transport characteristics of the prepared composite membranes were significantly affected by the variation of the support membrane mophology. The permeability of the composite membrane was decreased with increasing molecular weight cut-off of the support membrane, and the separation factor was slightly changed depending on the feed concentration.

• Membrane Journal
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• v.25 no.5
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• pp.391-397
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• 2015

The porous support polyvinylidene fluoride (PVDF) with a salting out based on the hollow fiber membrane polyethyleneimine (PEI) and polyvinylsulfonic acid (PVSA) by coating with by phase separated and pressurization (PSP) method to produce a multilayer membrane. The resulting membranes were characterized under the various conditions, such as the heat treatment temperature, coating concentration, feed concentration, cross-linking time and cross-link agent concentration in terms of flux and rejection rate for NaCl 100 ppm solution at 4 atm. The best results were PEI 20,000 ppm and PVSA 1,000 ppm, PEI 15% with a 2% malic acid aqueous solution coated by PSP method the hollow fiber membrane heat-treated for 1 minute showed flux 24.3 LMH, the rejection of 82.1%.

• Membrane Journal
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• v.22 no.1
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• pp.8-15
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• 2012

Tubular $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ membranes with $La_{0.6}Sr_{0.4}Ti_{0.3}Fe_{0.7}O_{3-{\delta}}$ porous coating layer were prepared by extrusion and dip coating technique. XRD and SEM result showed the tubular membrane possessed the perovskite structure and porouscoating layer (thickness= about $2{\mu}m$) in surface. The oxygen permeation test was measured at condition of ambient air (feed side) and vacuum (permeate side) in the temperature range from 750 to $950^{\circ}C$. The oxygen permeation flux of $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ tubular membrane with $La_{0.6}Sr_{0.4}Ti_{0.3}Fe_{0.7}O_{3-{\delta}}$ porous coating layer reached maximum $3.2mL/min{\cdot}cm^2$ at $950^{\circ}C$ and was higher than non-coated $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ tubular membrane. Long-term stability test result indicated that the oxygen permeation flux was quite stable during the 11 day.

• Journal of Pharmaceutical Investigation
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• v.22 no.3
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• pp.205-210
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• 1992

In order to develop a controlled-release oral drug delivery system (DDS) of theophylline (TP), microporous membrane-coated tablets were prepared and evaluated in vitro and in vivo. Rapidly water-soluble core tablets of TP (300 mg) were prepared by wet granulation and compression technique, Then the core tablets were spray-coated with polyvinylchloride (PVC) in which micronized sucrose particles were dispersed. Effect of formula compositions of coating suspensions on the pharmaceutical characteristics such as membrane strength and dissolution was investigated in vitro. The membranes remained unbroken in pH 1.2 buffer at $37^{\circ}C$ at least for 2 hours after the disintergration test. TP was released from the coated-released tablets at a zero-order rate over 8 hours. The release at pH 1.2 and 4.0 was similar in rate but a little more rapid than that at pH 6.8. The coated tablets were administered to three healthy male volunteers and their saliva profiles of TP were compared with those from the commercial sustained release TP tablets such as Slobid and Asconthin. Saliva TP concentrations from the coated tablets were successfully sustained over 48 hours after the dosing and were comparable to those of the commercial sustained-release tablets. The membrane-coating technique is very simple and does not need any sophisticated equipments. In this respect, the membrane-coated tablets may be superior to the commercial sustained-release tablets and this technique is worth adopting by the pharmaceutical industries.

• Journal of Korean Association for Spatial Structures
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• v.10 no.3
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• pp.41-48
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• 2010

The architectural membrane generally consists of weave and coating, and the PTFE membrane consists of fiberglass weave and polytetrafluoroethylene coating. The weave is usually made of fiberglass $\beta$-yarn. The $\alpha$-yarn, which is thicker than $\beta$-yarn, is also increasingly used for the weave. However, the characteristic data of the architectural membrane that is made of $\alpha$-yarn weave is still insufficient. Therefore, further studies are needed on the mechanical characteristics of the membrane according to the thickness of the yarn used for the weave that comprises the architectural membrane. This study was performed to identify the mechanical behaviors of the membranes with $\alpha$-yarn and $\beta$-yarn.

• Membrane Journal
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• v.28 no.3
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• pp.180-186
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• 2018

The nano-composite membranes were prepared onto the polyvinylidene fluoride (PVDF) hollow fiber membranes through twice dip-coating known layer-by-layer method. For the first coating, poly(vinylsulfonic acid, sodium salt)(PVSA) and Poly(styrene sulfonic acid)(PSSA) were used with varying the concentration and ionic strength (IS) and the poly(ethyleneimine)(PEI) as the second coating material was fixed at 10,000 ppm and IS = 0.3. To characterize the prepared nano-composite membranes, the permeabilities and rejection ratio were measured for each 100 ppm NaCl, $CaSO_4$, $MgCl_2$, and 25 ppm MO aqueous solution. The rejections were increased as the concentrations of coating materials increased. And it was confirmed that the salt rejections for PSSA as the coating material were higher than for PVSA. Typically, the permeability, 1.848 LMH and the rejection for MO 76.3% were obtained at the coating conditions of PSSA 30,000 ppm and I.S = 1.0.

• Membrane Journal
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• v.26 no.3
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• pp.205-211
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• 2016

Performance of pyrophyllite-based ceramic membranes newly developed were investigated. Membrane fouling caused by microbial suspensions taken from a full-scaled MBR system at domestic wastewater treatment plant was observed at different airflow rate and distance between each membrane. For the pyrophyllite support, pore size was about $1.0{\mu}m$, but surface coating with $Al_2O_3$ solution decreased the pore size with the reduction of the pure water permeability. With the MLSS taken from the full-scaled MBR system (6 g/L), the fouling rate was decreased by increasing airflow rate under $20L/m^2{\cdot}hr$ of setpoint flux. However, the effectiveness of the airflow rate on the fouling control depends strongly upon the gap between each membrane. At fixed airflow rate, the fouling rate was decreased by increasing the gap between each pyrophyllite membrane. Nevertheless, further increasing the membrane distance from 3.5 to 5.4 cm resulted in higher fouling rate. Similar result was observed with the $Al_2O_3$ coated-pyrophyllite membrane. Nevertheless, the fouling rate was lower with the coated membrane than that observed with the uncoated pyrophyllite support. Regardless of surface coating, the suspended solids were removed almost completely and the surface coating on the pyrophyllite support improved organic rejection with PEG solution (MW : 8000 kDa) tested.