• Macromolecular Research
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• v.17 no.9
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• pp.646-650
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• 2009

We report the fabrication of pentacene organic field-effect transistors (OFETs) using a fluorinated styrene-alt-maleic anhydride copolymer gate dielectric, which was prepared from styrene derivatives with a fluorinated side chain [$-CH_2-O-(CH_2)_2-(CF_2)_5CF_3$] and maleic anhydride through a solution polymerization technique. The fluorinated side chain was used to impart hydrophobicity to the surface of the gate dielectric and maleic anhydride was employed to improve its wetting properties. A field-effect mobility of 0.12 cm$^2$/Vs was obtained from the as-prepared top-contact pentacene FETs. Since various functional groups can be introduced into the copolymer due to the nature of maleic anhydride, its physical properties can be manipulated easily. Using this type of copolymer, the performance of organic FETs can be enhanced through optimization of the interfacial properties between the gate dielectric and organic semiconductor.

• Journal of the Korean Chemical Society
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• v.62 no.6
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• pp.427-432
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• 2018

The reaction of [$[Ni(L)]Cl_2{\cdot}2H_2O$ (L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo[$14,4,0^{1.18},0^{7.12}$]docosane) with 1,1-cyclohexanediacetic acid ($H_2cda$) yields mononuclear nickel(II) complex, [$Ni(L)(Hcda^-)_2$] (1). This complex has been characterized by X-ray crystallography, electronic absorption, cyclic voltammetry and thermogravimetric analyzer. The crystal structure of 1 exhibits a distorted octahedral geometry with four nitrogen atoms of the macrocycle and two 1,1-cyclohexanediacetate ligands. It crystallizes in the triclinic system P-1 with a = 11.3918(7), b = 12.6196(8), $c=12.8700(8){\AA}$, $V=1579.9(2){\AA}^3$, Z = 2. Electronic spectrum of 1 also reveals a high-spin octahedral environment. Cyclic voltammetry of 1 undergoes one wave of a one-electron transfer corresponding to $Ni^{II}/Ni^{III}$ process. TGA curve for 1 shows three-step weight loss. The electronic spectra, electrochemical and TGA behavior of the complex are significantly affected by the nature of the axial $Hcda^-$ ligand.

• Advances in nano research
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• v.4 no.4
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• pp.295-307
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• 2016

The present research work reports a low temperature ($40^{\circ}C$) chemical precipitation technique for synthesizing hydroxyapatite (HAp) nanoparticles of spherical morphology through a simple reaction of calcium nitrate tetrahydrate and di-ammonium hydrogen phosphate at pH 11. The crystallinity of the single-phase nanoparticles could be improved by calcinating at $600^{\circ}C$ in air. Thermogravimetric and differential thermal analysis (TG-DTA) revealed the synthesized HAp is stable up to $1200^{\circ}C$. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) studies confirmed the formation of spherical nanoparticles with average size of $23.15{\pm}2.56nm$ and Ca/P ratio of 1.70. Brunauer-Emmett-Teller (BET) isotherm of the nanoparticles revealed their porous structure with average pore size of about 24.47 nm and average surface area of $78.4m2g^{-1}$. Fourier transform infrared spectroscopy (FTIR) was used to confirm the formation of P-O, OH, C-O chemical bonds. Cytotoxicity and MTT assay on MG63 osteogenic cell lines revealed nontoxic bioactive nature of the synthesized HAp nanoparticles.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.12
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• pp.1178-1183
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• 2006

This paper is concerned with the modeling and identification of pH neutralization process as nonlinear chemical system. The pH control has been applied to various chemical processes such as wastewater treatment, chemical, and biochemical industries. But the control of the pH is very difficult due to its highly nonlinear nature which is the titration curve with the steepest slope at the neutralization point. We apply SVM which have become an increasingly popular tool for machine teaming tasks such as classification, regression or detection to model pH process which has strong nonlinearities. Linear and radial basis function kernels are employed and each result has been compared. So SVH based on kernel method have been found to work well. Simulations have shown that the SVM based on the kernel substitution including linear and radial basis function kernel provides a promising alternative to model strong nonlinearities of the pH neutralization but also to control the system.

• Bulletin of the Korean Chemical Society
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• v.30 no.1
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• pp.92-96
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• 2009

A new precursor [$Zr(acac)_{3}(H_{2}O)_{2}$] was synthesized by Sonochemical technique and used to deposit thin $ZrO_{2}$ film on quartz and ceramic substrate via ultrasonic aerosol assisted chemical vapour deposition (UAACVD) at 300 ${^{\circ}C}$ in oxygen environment followed by annealing of the sample for 2-3 minutes at 500 ${^{\circ}C}$ in nitrogen ambient. The molecular structure of the precursor determined by single crystal X-ray analysis revealed that the molecules are linked through intermolecular hydrogen bonds forming pseudo six and eight membered rings. DSC and TGA/FTIR techniques were used to determine thermal behavior and decomposition temperature of the precursor and nature of evolved gas products. The optical measurement of annealed $ZrO_{2}$ film with tetragonal phase shows optical energy band gap of 5.01 eV. The particle size, morphology, surface structure and composition of deposited films were investigated by XRD, SEM and EDX.

• Journal of Industrial Technology
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• v.43 no.1
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• pp.25-31
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• 2023

Stretchable and flexible electronics that comply with dynamic movements and micromotion of the human tissues can enable real-time monitoring of physiologic signals onto the human skin and in the brain, respectively. Especially, gallium based liquid metal stretchable electronics can offer human-interactive biosensors to monitor various physiologic parameters. However, the liquid-like nature, surface oxidation and contamination by organic materials, and low biostability of the liquid metals have still limited the long-term use as bioelectronics. Here we introduced electrochemical deposition without oxidation pathways to overcome these practical challenges in liquid metal bioelectronics. CNT/PDDA composite with reduction way and PEDOT:BF₄ with oxidation way under organic solvent are suggested as rationally designed material engineering approaches. We confirmed that the structures with the soft, flexible, and stretchable liquid metal platform can successfully detect dopamine with a high sensitivity and selectivity, record neural signals including action potentials without scar formation, and monitor physiologic signals such as EMG and ECG.

• Journal of Photoscience
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• v.3 no.1
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• pp.33-38
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• 1996

The effect of vesicular L-$\alpha$-phosphatidylcholine on the rate of formation of all-trans-N-retinylidene-n-butylamine (3) and on the regeneration kinetics of bacteriorhodopsin pigment from retinal and bacterio-opsin have been studied. An estimate of the relative positions of retinal and n-butylamine in the vesicles has been made by fluoresence quenching experiments. Partition coefficient of retinal and microviscosity of the retinal-binding region have also been determined. The results are discussed in terms of the nature of chemical interaction between retinal and amine in a lipid environment.

• Environmental Analysis Health and Toxicology
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• v.31
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• pp.8.1-8.2
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• 2016

A simple linear model to test the hypothesis based on one-on-one relationship has been used to find the causative factors of diseases. However, we now know that not just one, but many factors from different systems such as chemical exposure, genes, epigenetic changes, and proteins are involved in the pathogenesis of chronic diseases such as diabetes mellitus. So, with availability of modern technologies to understand the intricate nature of relations among complex systems, we need to move forward to the future by taking complex systems model.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.143-146
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• 2002

Saponins are glycosidic compounds present in many edible and inedible plants. Structurally, they are composed of a lipid-soluble aglycone consisting of either a sterol or, more commonly, a triterpenoid and water-soluble sugar residues differing in type and amount of sugars ［1］. Because of their amphiphilic nature, they are highly surface-active. Their biological activity is closely related to the chemical structures that determine the polarity, hydrophobicith and acidity of compounds ［1］. (omitted)

• Korean Journal of Pharmacognosy
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• v.33 no.4 s.131
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• pp.263-266
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• 2002

From the herbs of this plant, six compounds were isolated and their structures were characterized as dieicosyl ether (1), scopoletin (2), ${\alpha}-spinasterol-3-O-{\beta}-D-glucopyranoside$ (3), kaempferol (4), quercetin (5), and quercetin 7, 3', 4'-trimethylether-3-O-rutinoside (6) by chemical and spectroscopic evidences. These compounds were isolated for the first time from this plant and compound 6 was first isolated from nature.