• Journal of the Korean Society of Food Science and Nutrition
• /
• v.32 no.7
• /
• pp.960-964
• /
• 2003

Effects of pH, sugars, organic acids, and metal ions on the stability of anthocyanin pigments extracted from mulberry (Morus alba L) fruit were studied. The pH had marked influences on the color of the anthocyanine pigment: i.e. the lower pH of the anthocyanin solution was, the more stable and intense of the pigment was. Among the sugars, sucrose was the most deleterious followed by fructose, glucose and maltose. Among the organic acids, maleic acid was found to be the most effective in stabilizing the pigment followed by acetic acid, citric acid and tartaric acid. Most metal ions except C $u^{+2}$ and F $e^{+3}$ were found to be effective in stabilizing the pigment.

• Nuclear Engineering and Technology
• /
• v.50 no.1
• /
• pp.211-215
• /
• 2018

Chitosan was modified by gamma radiation-induced grafting with maleic acid and then used for the removal of cobalt ions from aqueous solutions. Chitosan-g-maleic acid was characterized by Fourier Transform infrared spectroscopy (FT-IR). The effect of the dose (1-5 kGy) and monomer concentration (0.3-1.3%, m/v) on the grafting ratio was examined. The adsorption kinetics and isotherms were also investigated. The results showed that the optimal dose for grafting was 2 kGy. When monomer concentration was within the range of 0.3-1.3% (m/v), the grafting ratio increased almost linearly. For the adsorption of cobalt ions by chitosan-g-maleic acid beads, the pseudo second-order kinetic model ($R^2=0.99$) and Temkin isotherm model ($R^2=0.96$) were able to fit the experimental data reasonably well. The equilibrium adsorption capacity of cobalt ions increased from 2.00 mg/g to 2.78 mg/g after chitosan modification.

• Restorative Dentistry and Endodontics
• /
• v.19 no.1
• /
• pp.45-63
• /
• 1994

128 freshly extracted human molars were used to study the interaction between dentinal smear layer removal with various agents, and the shear bond strength of a light cured glass ionomer cement to dentin. It was proposed that the removal of smear layers using acidic cleaners followed by incorporation of Fe mordant with dentin could enhanced the infiltration of monomer component in light curing glass ionomer cement and resulted in a high bond strength. For the first treatment process for removal of smear layers on the surfaces of dentin, 50 % citric acid, 10% maleic acid and 10 % phosphoric acid were used, and for the second treatment process, 15% ferric chloride, 6.8% ferric oxalate or 30% potassium oxalate were used. Distilled water was used as a control. After double sequential treatment on dentin, a light curing glass ionomer cement was bonded to dentin. After being immersed in water at 31'C for 24 hours, shear bond strengths were measured Instron testing machine(Model No.4202, USA). Surface changes were also observed using SEM (Hitachi, S-2300, Japan) after treatment process with each agents. The following conclusions were drawn : 1. Dentin surface cleaned with maleic acid and treated with ferric oxalate showed the highest bond strength with light curing glass ionomer cement. 2. Bond strengths of glass ionomer cement to dentin treated with maleic acid or citric acid were the highest, and that treated with phosphoric acid showed the lowest. 3. The effect of ferric oxalate on shear bond strength to dentin was always higher than that of ferric chloride. 4. The smear layers were clearly removed and the orifices of dentinal tubules were opened widely by the citric acid, maleic acid and phosphoric acid. 5. The orifices of dentinal tubules opened after using the first solution were closed with the treatment of ferric chloride. 6. The precipitate like crystals were formed on dentin surfaces and tubules, but a significant decrease in bond strength of glass ionomer cement to dentin surface treated with potassium oxalate.

• Journal of Adhesion and Interface
• /
• v.19 no.4
• /
• pp.145-153
• /
• 2018

In this study, adhesion promoters with acrylate and carboxylic acid moiety were synthesized from malenized polybutadiene and 2-hydroxyethyl acrylate for producing adhesive film with low water absorption and high adhesion. The surface properties, adhesion strength, mechanical properties and water absorption of adhesive films were characterized according to the amount of acrylate and carboxylic acid in the synthesized adhesion promoters. As the carboxylic acid in the adhesion promoters increased, the adhesion strength showed a tendency to increase and the mechanical properties also improved compared to the commercial adhesion promoter. The compatibility of adhesion promoters improved remarkably due to the presence of polybutadiene (hydrophobic nature), maleic anhydride (hydrophilic nature) and carboxylic acid (hydrophilic nature).

• Journal of the Korean Applied Science and Technology
• /
• v.32 no.4
• /
• pp.661-668
• /
• 2015

The surface rheological properties of polymer monolayer show complicated non-linear viscoelastic flow phenomena when they are subjected to spreading flow. These spreading flow properties are controlled by the characteristics of flow units. The kinetics of the formation of an interfacial film obtained after spreading poly(diisobutylene maleic acid) at air-water interface were studied by measuring of the surface pressure with time. The experimental data were analyzed theoretically according to a nonlinear surface viscoelastic model. The values of dynamic modulus, static modulus, surface viscosities and rheological parameters in various area/ monomer were obtained by appling experimental data to the equation of nonlinear surface viscoelastic model.

• Macromolecular Research
• /
• v.16 no.7
• /
• pp.659-662
• /
• 2008

A new and useful poly(ethylene oxide)-based pH-sensitive block copolymer is introduced. Poly(ethylene oxide-b-N-phenylmaleimide) was first synthesized by anionic polymerization of N-phenylmaleimide (N-PMI) using mixed alkali metal polymeric alkoxide by sequential monomer addition method in the mixture of benzene/THF/DMSO (10/5/3, v/v/v) at room temperature. Reductive deimidation of the resulting block copolymer was performed using hydrazine monohydrate leading to the formation of the corresponding pH-sensitive poly(ethylene oxide-b-maleic acid).

• Analytical Science and Technology
• /
• v.23 no.2
• /
• pp.165-171
• /
• 2010

Glucose oxidase ($GOD_{ox}$) immobilized biosensor was fabricated by two methods. In one of the methods, gold nanoparticles (Au-NPs) prepared by ${\gamma}$-irradiation were loaded into the poly(maleic anhydride)-grafted multi-walled carbon nanotube, PMAn-g-MWCNT electrode via physical entrapment. In the other method, the Au-NPs were prepared by electrochemical reduction of Au ions on the surface of PMAn-g-MWCNT electrode and then GODox was immobilized into the Au-NPs. The $GOD_{ox}$ immobilized biosensors were tested for electrocatalytic activities to sense glucose. The sensing range of the biosensor based on the Au-NPs physically modified PMAn-g-MWCNT electrode was from $30\;{\mu}M$ to $100\;{\mu}M$ for the glucose concentration, and the detection limit was $15\;{\mu}M$. Interferences of ascorbic acid and uric acid were below 7.6%. The physically Au deposited PMAn-g-MWCNT paste electrodes appear to be good sensor in detecting glucose.

• Journal of Oral Medicine and Pain
• /
• v.25 no.1
• /
• pp.129-144
• /
• 2000

The purpose of this study was to examine dentin surface changes of extracted sound third molar specimens which were etched with 10% maleic acid and irradiated at $7-140J/cm^2$ with $CO_2$ and at $156-280J/cm^2$ with Nd:YAG laser. The results were as follows. 1. Dentin surfaces etched with 10% maleic acid and then irradiated at below of $42J/cm^2$ with $CO_2$ laser showed the retentive morphology for resin restoration. 2. Dentin surfaces irradiated at below of $42J/cm^2$ with $CO_2$ laser showed the increased acid-resistance. 3. Dentin surfaces irradiated at $218-280J/cm^2$ with Nd:YAG laser showed the retentive morphology. 4. Dentin surfaces irradiated at $218-280J/cm^2$ with Nd:YAG laser and etched 10% maleic acid and then $218-280J/cm^2$ with Nd:YAG laser showed the increased acid-resistance.

• Membrane Journal
• /
• v.12 no.4
• /
• pp.255-261
• /
• 2002

Poly(vinyl alcohol) (PVA) membranes crosslinked with poly(acrylic acid-co-maleic anhydride) (PAM) as a polymeric crosslinking agent were prepared to investigate the pervaporation performance for the dehydration separation of aqueous ethanol solution. The characteristics of the resulting membranes crosslinked(x) were analysed by FT-IR and water swelling test. The water swelling decreased with increasing crosslinking agent content. The crosslinked PVA membranes with PAM showed lower water swelling than those of PVA membrane crosslinked with glutaraldehyde and modified PVA membrane. The swelling of water molecules in the crosslinked PVA membranes is more restricted by both chemical crosslinking between PVA and polymeric crosslinking agent chains and physical crosslinking by the entanglement between the PVA and polymeric crosslinking agent chains. For the pervaporation of aqueous ethanol solution through the crosslinked membrane, as the contents of crosslinking agent increased, the separation factor increased while the permeation flux decreased. The separation factor slightly decreased and permeation flux increased with increasing feed water content. As a result it could be considered that PVA-PAM membranes suppressed the plasticization effect even in the range of high water concentration in fled.

• Applied Chemistry for Engineering
• /
• v.17 no.5
• /
• pp.498-503
• /
• 2006

i-(2',5'-Diketotetrahydrofuranyl)octadecenyl acid (OSA), an intermediate for the lubricating oil additive, was prepared by the ene-reaction of oleic acid with maleic anhydride. The reaction progress was monitored by gas chromatography by analyzing the amount of OSA. The series of succinimidyl compounds were synthesized by the reaction of alkyl amines and OSA. As a kind of lubricant additives, demulsibility, anti-wear, and anti-corrosion properties of these succinimidyl compounds were measured. The derivative of octadecylamine which has relatively long-chained alkyl group has showed good properties.