• Title/Summary/Keyword: polyacrylic acid

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Improvement of Electrochemical Performance of KVO3 as High Capacity Negative Electrode Material for Lithium-ion Batteries (리튬이온 이차전지용 고용량 KVO3 음극의 전기화학적 성능개선)

  • Kim, Tae Hun;Gim, Gyeong Rae;Park, Hwandong;Kim, Haebeen;Ryu, Ji Heon
    • Journal of the Korean Electrochemical Society
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    • v.22 no.4
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    • pp.148-154
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    • 2019
  • Vanadium oxide based materials have been studied as novel negative electrode materials in lithium-ion batteries (LIBs) because of their high specific capacity. In this study, potassium metavanadate ($KVO_3$) was synthesized and its electrochemical properties are evaluated as a negative electrode materials. The aqueous solution of $NH_4VO_3$ is mixed with a stoichiometric amount of KOH. The solution is boiled to remove $NH_3$ gas and dried to obtain a precipitate. The obtained $KVO_3$ powders are heat-treated at 300 and $500^{\circ}C$ for 8 h in air. As the heat treatment temperature increases, the initial reversible capacity decreases, but the cycle performance and Coulombic efficiency are improved slightly. On the contrary, the electrochemical performances of the $KVO_3$ electrodes are greatly improved when a polyacrylic acid (PAA) as binder was used instead of polyvinylidene fluoride (PVDF) and a fluoroethylene carbonate (FEC) was used as electrolyte additive. The initial reversible capacity of the $KVO_3$ is 1169 mAh/g and the Coulombic efficiency is improved to 76.3% with moderate cycle performance. The $KVO_3$ has the potential as a novel high-capacity negative electrode materials.

Difference in Bonding Strength of RMGIC according to Type of Hemostatic Agent in Primary Tooth (지혈제의 종류에 따른 레진 강화형 글라스아이오노머 시멘트 결합력의 차이)

  • Back, Seolah;Lee, Joonhaeng;Kim, Jongbin;Han, Miran;Kim, Jong Soo
    • Journal of the korean academy of Pediatric Dentistry
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    • v.48 no.4
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    • pp.460-466
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    • 2021
  • The purpose of this study was to compare the effect of the hemostatic agent containing aluminum chloride with hemostatic agent containing ferric sulfate on the shear bond strength of resin-modified glass ionomer cement(RMGIC) to dentin in primary tooth. Twenty extracted non-carious human primary teeth were collected in this study. The specimens were cut to expose dentin and polished. The specimens were randomly seperated into 3 groups for treatment; group I: polyacrylic acid(PAA), RMGIC; group II: aluminum chloride, PAA, RMGIC; group III: ferric sulfate, PAA, RMGIC Ten specimens from each group were subjected to shear bond strength test. The mean shear bond strength of each group was as follows: 10.07 ± 1.83 MPa in Group I, 7.62 ± 0.78 MPA in group II, 5.23 ± 0.78 MPa in group III. There were significant differences among all groups(p < 0.001). In conclusion, both aluminum chloride hemostatic agent and ferric sulfate hemostatic agent decreased the shear bond strength of RMGIC to dentin. And ferric sulfate hemostatic agent decreased the shear bond strength of RMGIC more than the aluminium chloride hemostatic agent.

Effect of Aluminum Chloride Hemostatic Agent on Bonding Strength of RMGIC in Primary Tooth (염화알루미늄 지혈제가 유치와 레진강화형 글라스아이오노머 시멘트의 결합강도에 미치는 영향)

  • Woo, Seung-Hee;Shin, Jisun;Lee, Joonhaeng;Han, Miran;Kim, Jong Soo
    • Journal of the korean academy of Pediatric Dentistry
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    • v.48 no.4
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    • pp.397-404
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    • 2021
  • The purpose of this study was to evaluate the effect of a hemostatic agent containing aluminum chloride on the shear bond strength of resin-modified glass ionomer cement (RMGIC) to the dentin of primary teeth. Thirty-six extracted non-carious human primary teeth were collected in this study. Dentin surfaces were cut and polished. The specimens were randomly divided into 4 groups; group I: RMGIC without conditioning; group II: polyacrylic acid (PAA), RMGIC; group III: aluminum chloride, RMGIC; group IV: aluminum chloride, PAA, RMGIC. All teeth were thermocycled between 5.0℃ and 55.0℃ for 5000 cycles. Fifteen specimens from each group were subjected to shear bond strength test and 3 specimens from each group were inspected using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy. The mean shear bond strength of each group was as follows: 4.04 ± 0.88 MPa in group I, 8.29 ± 1.40 MPa in group II, 1.39 ± 0.47 MPa in group III, 6.24 ± 2.76 MPa in group IV. There were significant differences among all groups (p < 0.001). SEM image of the dentinal tubules were partially exposed in group III and group IV. Fully exposed dentinal tubules were found in group II. In conclusion, aluminum chloride decreased the shear bond strength of RMGIC to dentin, regardless of PAA conditioning.

Effect of Binder and Electrolyte on Electrochemical Performance of Si/CNT/C Anode Composite in Lithium-ion Battery (리튬이온 이차전지에서 Si/CNT/C 음극 복합소재의 전기화학적 성능에 대한 바인더 및 전해액의 효과)

  • Choi, Na Hyun;Kim, Eun Bi;Yeom, Tae Ho;Lee, Jong Dae
    • Korean Chemical Engineering Research
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    • v.60 no.3
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    • pp.327-333
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    • 2022
  • In this study, silicon/carbon nanotube/carbon (Si/CNT/C) composites for anode were prepared to improve the volume expansion of silicon used as a high-capacity anode material. Si/CNT were prepared by electrostatic attraction of the positively charged Si and negatively charged CNT and then hydrothermal synthesis was performed to obtain the spherical Si/CNT/C composites. Poly(vinylidene fluoride) (PVDF), polyacrylic acid (PAA), and styrene butadiene rubber (SBR) were used as binders for electrode preparation, and coin cell was assembled using 1.0 M LiPF6 (EC:DMC:EMC = 1:1:1 vol%) electrolyte and fluoroethylene carbonate (FEC) additive. The physical properties of Si/CNT/C anode materials were analyzed using SEM, EDS, XRD and TGA, and the electrochemical performances of lithium-ion batteries were investigated by charge-discharge cycle, rate performance, dQ/dV and electrochemical impedance spectroscopy tests. Also, it was confirmed that both capacity and rate performance were significantly improved using the PAA/SBR binder and 10 wt% FEC-added electrolyte. It is found that Si/CNT/C have the reversible capacity of 914 mAh/g, the capacity retention ratio of 83% during 50 cycles and the rate performance of 70% in 2 C/0.1 C.

Polymer Effects on Appetite Suppression by Lipoic Acid Nanoparticles (리포익산 나노 입자의 식욕 억제에 대한 고분자의 영향)

  • Choi, Hye-Min;Park, Chul-Ho;Lee, Ki-Up;Park, Joong-Yeol;Koh, Eun-Hee;Kim, Hyoun-Sik;Lee, Jong-Hwi
    • Journal of Pharmaceutical Investigation
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    • v.37 no.6
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    • pp.349-354
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    • 2007
  • For decades, the various virtues of ${\alpha}-lipoic$ acid (ALA), a natural material synthesized in most cells, have been intensively studied and proved. Recently it was reported that ALA caused significant bodyweight reduction via appetite suppression. Unfortunately, the efficacy requires an administration over 50 mg/kg. The low bioavailability and the short plasma half life of ALA lead us to explore novel pharmaceutical dosage forms using nanoparticles. In this study, the effect of polymeric stabilizers on the bioavailability improvement of ALA nanoparticles was investigated. The reduction of particle size via nano-comminution technology was successful resulting in volume average particle sizes of 320 - 340 nm. The in vitro release rate of ALA did not reflect the decrease of particle size, possibly because of the self polymerization of ALA during nano-comminution. The type of polymeric stabilizers could not affect the release rate either. However, the in vivo food intake results of ALA showed that nano-suspensions were more effective than microparticles or a salt form. The nano-suspension containing polyvinyl pyrrolidone as the primary stabilizer and polyacrylic acid as the secondary stabilizer showed more improved efficacy for 2 hours.

Polymer-directed Crystallization of Sibutramine using Cellulose Derivatives

  • Bae, Ha-Rim;Lee, Hye-Seung;Lee, Min-Kyung;Lee, Jong-Hwi
    • Journal of Pharmaceutical Investigation
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    • v.41 no.1
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    • pp.45-50
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    • 2011
  • Nonclassical pathway of crystallization has been utilized to modify the properties and morphologies of inorganic and organic/inorganic materials. In here, the polymer-directed crystallization method has been applied to the pharmaceutical active ingredient to assess the applicability for as a particle engineering tool. The polymer-directed crystallization was successful to modifying the crystal size, habit and morphology, but it was not effective to discover the novel polymorphs of Sibutramine (SB). SB was selected as a model drug and polyacrylic acid (PAA), polyethylene imine (PEI) and chitosan (CHI) were added as a crystallization pathway modifier. SB was crystallized via drowning crystallization using methanol or ethanol as a solvent and water as a non-solvent. The significant interactions between polymer and the drug were confirmed by measuring the solubility of the drug in presence of polymer during the crystallization. The crystal forms of SB are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and optical microscope (OM). The polymer-directed crystallization seems to be able to modify the crystal properties of pharmaceutical active ingredient, which is critical in determining the bioavailability, processability, and stability.

Eco-friendly Textile Printing using Marigold Pigment(1): Effect of Binder Type and Mixing Ratio (메리골드 안료를 이용한 친환경 텍스타일 프린팅(1): 바인더의 종류와 혼합비율의 효과)

  • Yeo, Youngmi;Shin, Younsook
    • Textile Coloration and Finishing
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    • v.31 no.4
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    • pp.233-240
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    • 2019
  • Dyeing is an essential process for improving the value of textile products, but it is considered as one of industries causing pollution because of producing wastewater containing hazardous chemicals as well as using a large amount of water and energy. Global demand for greener technologies in textile field is getting much more attention and accordingly, the use of eco-friendly natural dyes is growing much larger. In textile printing, both dyes and pigments can be used. Pigment printing is more simple process and requires less water and less energy, compared to dye printing. In this study, the organic pigment was prepared from the marigold colorant. Samples were stencil printed, pressed(70℃, 3min) and then heat treated(150℃, 5min). The uptake of polyacrylic acid as a chemical binder was the lowest. In particular, marigold pigments were excellent in color and texture when Guar Gum and Sodium Alginate were used as binders. In addition, the light and washing fastness was rated very high as 4, 4/5 grades, and the rubbing fastness was also excellent as 3 and 4 grades.

Effects of Electrolyte Concentration on Electrochemical Properties of Zinc-Air Batteries (전해질 농도에 따른 아연-공기 전지의 전기화학적 특성)

  • Han, Ji Woo;Jo, Yong Nam
    • Korean Journal of Materials Research
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    • v.29 no.12
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    • pp.798-803
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    • 2019
  • The self-discharge behavior of zinc-air batteries is a critical issue induced by corrosion and hydrogen evolution reaction (HER) of zinc anode. The corrosion reaction and HER can be controlled by a gelling agent and concentration of potassium hydroxide (KOH) solution. Various concentrations of KOH solution and polyacrylic acid have been used for gel electrolyte. The electrolyte solution is prepared with different concentrations of KOH (6 M, 7 M, 8 M, 9 M). Among studied materials, the cell assembled with 6 M KOH gel electrolyte exhibits the highest specific discharge capacity and poor capacity retention. Whereas, 9 M KOH gel electrolyte shows high capacity retention. However, a large amount of hydrogen gas is evolved with 9 M KOH solution. In general, the increase in concentration is related to ionic conductivity. At concentrations above 7 M, the viscosity increases and the conductivity decreases. As a result, compared to other studied materials, 7 M KOH gel electrolyte is suitable for Zn-air batteries because of its higher capacity retention (92.00 %) and specific discharge capacity (351.80 mAh/g) after 6 hr storage.

Cadmium and zinc removal from water by polyelectrolyte enhanced ultrafiltration

  • Ennigrou, Dorra Jellouli;Ali, Mourad Ben Sik;Dhahbi, Mahmoud;Mokhtar, Ferid
    • Membrane and Water Treatment
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    • v.5 no.3
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    • pp.183-195
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    • 2014
  • The efficiency of two metal ions (cadmium, zinc) removal from aqueous solutions by ultrafiltration (UF) and Polymer Enhanced Ultrafiltration (PEUF) processes were investigated in this work. The UF and PEUF studies were carried out using an ultrafiltration tangential cell system equipped with 5.000 MWCO regenerated cellulose. A water-soluble polymer: the polyacrylic acid (PAA) was used as complexant for PEUF experiments. The effects of transmembrane pressure, pH, metal ions and loading ratio on permeate fluxes and metal ions removals were evaluated. In UF process, permeate fluxes increase linearly with increasing pH for different transmembrane pressure, which may be the consequence of the formation of soluble metal hydroxyl complexes in the aqueous phase. In PEUF process, above pH 5.0, the Cd(II) retention reaches a plateau at 90% and Zn(II) at 80% for L = 5. Also, cadmium retention at different L is greater than zinc retention at pH varying from 5.0 to 9.0. In a mixture solution, cadmium retention is higher than zinc for different loading ratio, this is due to interactions between carboxylic groups of PAA and metal ions and more important with cadmium ions.

Bonding of a resin-modified glass ionomer cement to dentin using universal adhesives

  • Ugurlu, Muhittin
    • Restorative Dentistry and Endodontics
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    • v.45 no.3
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    • pp.36.1-36.10
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    • 2020
  • Objectives: This study aims to assess the effect of universal adhesives pretreatment on the bond strength of resin-modified glass ionomer cement to dentin. Materials and Methods: Fifty caries-free human third molars were employed. The teeth were randomly assigned into five groups (n = 10) based on dentin surface pretreatments: Single Bond Universal (3M Oral Care), Gluma Bond Universal (Heraeus Kulzer), Prime&Bond Elect (Dentsply), Cavity Conditioner (GC) and control (no surface treatment). After Fuji II LC (GC) was bonded to the dentin surfaces, the specimens were stored for 7 days at 37℃. The specimens were segmented into microspecimens, and the microspecimens were subjugated to microtensile bond strength testing (1.0 mm/min). The modes of failure analyzed using a stereomicroscope and scanning electron microscopy. Data were statistically analyzed with one-way analysis of variance and Duncan tests (p = 0.05). Results: The surface pretreatments with the universal adhesives and conditioner increased the bond strength of Fuji II LC to dentin (p < 0.05). Single Bond Universal and Gluma Bond Universal provided higher bond strength to Fuji II LC than Cavity Conditioner (p < 0.05). The bond strengths obtained from Prime&Bond Elect and Cavity Conditioner were not statistically different (p > 0.05). Conclusions: The universal adhesives and polyacrylic acid conditioner could increase the bond strength of resin-modified glass ionomer cement (RMGIC) to dentin. The use of universal adhesives before the application of RMGIC may be more beneficial in improving bond strength.