• Biomaterials Research
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• v.22 no.4
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• pp.235-248
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• 2018

Background: Injectable hydrogels have been extensively researched for the use as scaffolds or as carriers of therapeutic agents such as drugs, cells, proteins, and bioactive molecules in the treatment of diseases and cancers and the repair and regeneration of tissues. It is because they have the injectability with minimal invasiveness and usability for irregularly shaped sites, in addition to typical advantages of conventional hydrogels such as biocompatibility, permeability to oxygen and nutrient, properties similar to the characteristics of the native extracellular matrix, and porous structure allowing therapeutic agents to be loaded. Main body: In this article, recent studies of injectable hydrogel systems applicable for therapeutic agent delivery, disease/cancer therapy, and tissue engineering have reviewed in terms of the various factors physically and chemically contributing to sol-gel transition via which gels have been formed. The various factors are as follows: several different non-covalent interactions resulting in physical crosslinking (the electrostatic interactions (e.g., the ionic and hydrogen bonds), hydrophobic interactions, ${\pi}$-interactions, and van der Waals forces), in-situ chemical reactions inducing chemical crosslinking (the Diels Alder click reactions, Michael reactions, Schiff base reactions, or enzyme-or photo-mediated reactions), and external stimuli (temperatures, pHs, lights, electric/magnetic fields, ultrasounds, or biomolecular species (e.g., enzyme)). Finally, their applications with accompanying therapeutic agents and notable properties used were reviewed as well. Conclusion: Injectable hydrogels, of which network morphology and properties could be tuned, have shown to control the load and release of therapeutic agents, consequently producing significant therapeutic efficacy. Accordingly, they are believed to be successful and promising biomaterials as scaffolds and carriers of therapeutic agents for disease and cancer therapy and tissue engineering.

• Membrane and Water Treatment
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• v.8 no.2
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• pp.113-123
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• 2017

This study investigated effects of physical and chemical cleaning methods on the initial flux recovery of fouled membrane in membrane distillation process. A laboratory scale direct contact membrane distillation (DCMD) experiment was performed to treat digested livestock wastewater with 3.89 mg/L suspended solids, 874.7 mg/L COD, 543.7 mg/L nitrogen, 15.6 mg/L total phosphorus, and pH of 8.6. A hydrophobic PVDF membrane with an average pore size of $0.22{\mu}m$ and a porosity of 75 % was installed inside a direct contact type membrane distillation module. The temperature difference between feed and permeate side was maintained at $40^{\circ}C$ with the feed and permeate stream velocity of 0.18 m/s. The results showed that the permeate flux decreased from $22.1L{\cdot}m^{-2}{\cdot}hr^{-1}$ to $19.0L{\cdot}m^{-2}{\cdot}hr^{-1}$ after 75 hours of distillation. The fouled membrane was cleaned first by physical flushing and consecutively by chemicals with NaOCl and citric acid. After the physical cleaning the flux was recovered to 92 % as compared with the initial clean water flux of the virgin membrane. Then 94 % of the flux was recovered after cleaning by 2,000 ppm NaOCl for 90 minutes and finally 97 % of flux recovered after 3 % citric acid for 90 minutes. SEM-EDS and FT-IR analysis results presented that the foulants on the membrane surface were removed effectively after each cleaning step. The contact angle measurement showed that the hydrophobicity of the membrane surface was also restored gradually after each cleaning step to reach nearly the same hydrophobicity level as the virgin membrane.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.10
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• pp.1668-1675
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• 2004

The effect of pH on surface hydrophobicity, sulfhydryl group, infrared spectrum, SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis) pattern and enthalpy was investigated in recovered protein from mackerel and frozen blackspotted croaker by alkaline processing. Hydrophobic residue in myofibrillar protein exposed to the surface of protein, and hydrophobic interaction were the highest around 6$0^{\circ}C$. The surface hydrophobicity was different between myofibrillar protein and myofibrillar protein including sarcoplasmic protein (recovered protein). The peak at 1636 c $m^{-l}$ was increased with pH, and the recovered protein was unfolded in alkali pH. Difference of surface and total sulfhydryl group at pH 7.0 and 10 was comparative high, and decrease of surface sulfhydryl group indicated formation of S-S bonds. Mackerel and frozen blackspotted croaker in alkaline pH showed bands of polymerized myosin heavy chain on SDS-PAGE pattern. The transition temperatures of recovered protein were 33.1, 44.3 and 65.5$^{\circ}C$. Gelation of recovered protein from alkali processing was estimated by increase of $\beta$-sheet structure by pH treatment, S-S bonds by oxidation of surface sulfhydryl group in heating, polymerization of myosin heavy chain in order.r.

• Applied Chemistry for Engineering
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• v.24 no.5
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• pp.544-550
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• 2013

This work investigated the environmental application of an underwater dielectric barrier discharge plasma reactor consisting of a porous hydrophobic ceramic tube to the decolorization of an azo dyeing wastewater. The reactive species generated by the plasma are mostly short-lived, which also need to be transferred to the wastewater right after the formation. Moreover, the gas-liquid interfacial area should be as large as possible to increase the decolorization rate. The arrangement of the present wastewater treatment system capable of immediately dispersing the plasmatic gas as tiny bubbles makes it possible to effectively decolorize the dyeing wastewater alongside consuming less amount of electrical energy. The effect of discharge power, gas flow rate, dissolved anion and initial dye concentration on the decolorization was examined with dry air for the creation of plasma and amaranth as an azo dye. At a gas flow rate of $1.5Lmin^{-1}$, the good contact between the plasmatic gas and the wastewater was achieved, resulting in rapid decolorization. For an initial dye concentration of $40.2{\mu}molL^{-1}$ (volume : 0.8 L; discharge power : 3.37 W), it took about 25 min to attain a decolorization efficiency of above 99%. Besides, the decolorization rate increased with decreasing the initial dye concentration or increasing the discharge power. The presence of chlorine anion appeared to slightly enhance the decolorization rate, whereas the effect of dissolved nitrate anion was negligible.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.5
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• pp.263-271
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• 2003

Effects of the existence of $CO_2$ gas and pH on the silica surface characteristics at silica/Pb(II) and sodium dodecyl sulfonate (SDS, $C_{12}H_{25}SO_3Na$) solution interface were studied. The hydrophobic characteristics of silica surface was delineated by contact angle measurement and surface force measurement using atomic force microscopy (AFM). In $CO_2$ free condition provided by purging $N_2$ gas, the contact angle of fused silica surface in $10^{-4}M$ Pb(II) and SDS solution increased greatly up to $90^{\circ}$ compared with $40^{\circ}$ in atmospheric condition. It was due to the precipitation of $PbCO_3$ in atmospheric condition. In $CO_2$ free condition the change of contact angle and adhesion force ($F_{ad}$) in AFM, affected by pH change, was similar to the distribution of $PbOH^+$ ion in speciation diagram corresponding to $10^{-4}M$ total Pb(II). Therefore, it was convinced that the $PbOH^+$ ion among Pb(II) species would be the main adsorbing type on silica surface. Both of contact angle measurement and surface force measurement using AFM showed that the Pb only treatment made the silica surface hydrophobic. However, it could not be explained theoretically by current knowledge, and required further study in atomic level to solve the problem.

• Journal of the Korean Electrochemical Society
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• v.26 no.4
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• pp.43-55
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• 2023

Mass transport through nanoporous structures such as nanopores or nanochannels has fundamental electrochemical implications and many potential applications as well. These structures can be particularly useful for water treatment, energy conversion, biosensing, and controlled delivery of substances. Earlier research focused on creating nanopores with diameters ranging from tens to hundreds of nanometers that can selectively transport cationic or anionic charged species. However, recent studies have shown that nanopores with diameters of a few nanometers or even less can achieve more complex and versatile transport control. For example, nanopores that mimic biological channels can be functionalized with specific receptors to detect viruses, small molecules, and even ions, or can be made hydrophobic and responsive to external stimuli, such as light and electric field, to act as efficient valves. This review summarizes the latest developments in nanopore-based systems that can control mass transport based on the size of the nanopores (e.g., length, diameter, and shape) and the physical/chemical properties of their inner surfaces. It also provides some examples of practical applications of these systems.

• Archives of Plastic Surgery
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• v.33 no.1
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• pp.46-52
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• 2006

High-density micromass culture was needed to take three dimensions culture with ASCs(adipose derived stromal cells) and chondrogenesis. However, the synthetic polymer has hydrophobic character and low affinity to cells and other biomolecules. Therefore, the surface modification without changes of physical and chemical properties is necessary for more suitable condition to cells and biomolecules. This study was performed to investigate the effect of surface modification of poly (lactic-co-glycolic acid)(PLGA) scaffold by plasma treatment (P(+)) on the adhesion, proliferation and chondrogenesis of ASCs, and not plasma treatment (P(-)). ASCs were isolated from human subcutaneous adipose tissue obtained by lipectomy and liposuction. At 1 hour 30 minutes and 3days after cell seeding onto the P(-) group and the P(+) group, total DNA amount of attached and proliferated ASCs markedly increased in the P(+) group (p < 0.05). The changes of the actin under confocal microscope were done for evaluation of cellular affinity, at 1 hour 30 minutes, the shape of the cells was spherical form in all group. At 3rd day, the shape of the cells was fiber network form and finely arranged in P(+) group rather than in P(-) group. RT-PCR analysis of cartilage-specific type II collagen and link protein were expressed in 1, 2 weeks of induction. Amount of Glycoaminoglycan (GAG) markedly increased in P(+) group(p < 0.05). In a week, extracellular matrix was not observed in the Alcian blue and Safranin O staining. However in 2 weeks, it was observed that sulfated proteoglycan increased in P(+) group rather than in P(-) group. In conclusion, we recognized that plasma treatment of PLGA scaffold could increase the hydrophilic property of cells, and provide suitable environment for high-density micromass culture to chondrogenesis

• Korean Journal of Soil Science and Fertilizer
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• v.18 no.4
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• pp.373-377
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• 1985

This experiment was designed to find out the soil properties to control the soil erodibility. Two kinds of soil conditioners, hydrophilic Uresol and hydrophobic Bitumen were treated to sandy loam and silt loam. Soil erodibility was tested during a simulated rainfall in a soil pan which was covered with a 2cm layer of treated and untreated aggregates (< 5.36mm) on a soil layer. The runoff starting time was delayed 8-20 minutes by Uresol treatment and it was hasten 1-21 minutes by Bitumen treatment. Runoff rates were reduced by Uresol to 62.5% in sandy loam and 93.7% in silt loam, but it was increased by Bitumen treatment. Erosion from the Uresol treated soil was remarkably reduced to 1.7-23.6% of that in the untreated soil. In case of the Bitumen treatment, the soil loss from silt loam was reduced to 55.5% of the control, but it was increased in sandy loam soil by 52% over the control. The ratio of soil loss and runoff, sediment concentration in runoff, was noticeably increased when the soil structure was unstable. There was significant correlation between soil loss and logarithm of wetting angle-stability index. Soil loss was greatly increased when the index was less than 0.2.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.10
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• pp.1099-1107
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• 2005

The purpose of this study was to find the transformation of organic matter as well as chlorine by product formation potential with ozone dosage. The removal percents of $UV_{254}$ and DOC were $23%{\sim}65%$ and $2%{\sim}15%$ and THMFP and HAAFP were $17%{\sim}52%$ and $9%{\sim}29%$ respectively at $0.5{\sim}3\;mgO_3/mgDOC$ ozone dosage. The hydrophobic and transphobic organic matter were reduced to $37%{\sim}68%$ and $35%{\sim}64%$, on the other hand the hydrophilir organic matter was increased to $40%{\sim}49%$ at $0.5{\sim}3\;mgO_3/mgDOC$ ozone dosage. The produced THMFP and HAAFP from the hydrophobic and transphilic organic matter were decreased greatly with increasing ozone dosage but these by products were increased in the hydrophilic matter. The produced THMFP and HAAFP per unit DOC were decreased and reactivity was reduced greatly with increasing crone dosage. The removal rate of THMFP per unit DOC was much higher than HAAFP by ozone treatment. The Br-THMFP per unit DOC was much more removed than chloroformFP per unit DOC with increasing ozone dosage. and The removal rate of TCAAFP per unit DOC was increased with increasing ozone dosage but TCAAFP was not affected by ozone treatment. Br-HAAFP was decreased at $1\;mgO_3/mgDOC$ ozone dosage but was not more removed above $1\;mgO_3/mgDOC$ ozone dosage. Br-HAAFP had lower removal effect than Br-THMFP by ozone treatment. The optimal ozone dosage can be determined about $1\;mgO_3/mgDOC$ by considering both disinfection by product formation and economical efficiency.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.420-430
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• 2005

This study was performed to change the hydrophilic $NH_4Y$-zeolite to the hydrophobic one for removal of VOCs by removing the $Al^{3+}$ in the zeolite-structure to increase the Si/Al ratio, for which the three pelleted $NH_4Y$-zeolite samples were contacted separately with the steam of $400^{\circ}C$, $500^{\circ}C$ and $600^{\circ}C$, respectively, in a stainless steel column for 4 hours. Then extraction of the ex-structure aluminum of the hydrolyzed zeolites with the nitric acids of 0.25, 0.50, 0.75, and 0.10 M at $90^{\circ}C$ in 500 mL-flasks, respectively, according to steam temperature were followed. XRD analysises of the dealuminated zeolites showed that the peaks of the zeolites that had been hydrolyzed with the steams of both $500^{\circ}C$ and $600^{\circ}C$ are distorted more with the increase of the concentration of nitric acid used for extraction of the ex-structure aluminums, however, those hydrolyzed with steam of $400^{\circ}C$ became amorphous phase when treated with the all nitric acids of four concentrations. Also the EDX analysises showed that the BET surface areas and TPVS of the zeolites that had been hydrolyzed with the steam of $600^{\circ}C$ were increased with the concentration of the nitric acid when the nitric acids of 0.25 M and 0.5 M had been used but decreased when the nitric acids of 0.75 M and 1.0 M had been used. These results led to the conclusion that both the $600^{\circ}C$ and $500^{\circ}C$-steam and the 0.5 M-nitric acid are appropriate to change the hydrophilic $NH_4Y$-zeolites to the hydrophobic one, which were proven by the measurement of the benzene and tolune-adsorbing capacities showing the same trend as the BET surface area and TPV The Si/Al ratios and water-adsorbing capacities of the dealuminated zeolites were increased and decreased, respectively, with the concentration of the nitric acids so that it showed that the hydrophobicity is increased.