• Bulletin of the Korean Chemical Society
• /
• v.25 no.11
• /
• pp.1661-1666
• /
• 2004

The reaction of titanium tetraisopropoxide with 2 equiv of N,N-diethyl acetoacetamide affords Ti($O^iPr)_2(CH_3COCHCONEt_2)_2$ (1) as colorless crystals in 80% yield. Compound 1 is characterized by spectroscopic (Mass and $^1H/^{13}C$ NMR) and microanalytical data. Molecular structure of 1 has been determined by a single crystal X-ray diffraction study, which reveals that it is a monomeric, cis-diisopropoxide and contains a six coordinate Ti(IV) atom with a cis($CONEt_2$), trans($COCH_3$) configuration (1a) in a distorted octahedral environment. Variable-temperature $^1H$ NMR spectra of 1 indicate that it exists as an equilibrium mixture of cis, trans (1a) and cis, cis (1b) isomers in a 0.57 : 0.43 ratio at -20$^{\circ}C$ in toluene-$d_8$ solution. Thermal properties of 1 as a MOCVD precursor for titanium dioxide films have been evaluated by thermal gravimetric analysis and vapor pressure measurement. Thin films of pure anatase titanium dioxide (after annealing above 500$^{\circ}C$ under oxygen) have been grown on Si(100) with precursor 1 in the substrate temperature range of 350- 500$^{\circ}$ using a bubbler-based MOCVD method.

• Korean Journal of Medicinal Crop Science
• /
• v.16 no.4
• /
• pp.268-272
• /
• 2008

The effect of elicitor and precursor on salidroside production from Rhodiola sachalinensis A.Bor callus cultures was investigated. Callus cultures were treated with yeast extract, soft-ferrite ceramics powder, methyl jasmonate, ascorbic acid, jasmonic acid and $CuCl_2$/$CdCl_2$ as an elicitor. When callus cultures were treated with $0.2g/\ell$ of yeast extract, salidroside production from callus treated with yeast extract is 3.45 times higher than that of the controlled group. Among of them, callus cultures treated with yeast extract produced the highest salidroside. Callus cultures were treated with L-phenylalanine and L-tyrosine as a precursor for 4 days. The result of salidroside content analysis showed that all feeding of precursors not affected salidroside production from callus cultures. In case of L-tyrosine fed into callus cultures, both callus growth and salidroside production decreased at all concentrations.

• Composites Research
• /
• v.34 no.1
• /
• pp.23-29
• /
• 2021

Commercialized carbon fiber obtained from polyacrylonitrile(PAN) precursor is subjected to oxidation stabilization at 180 to 300℃ in air atmosphere and carbonization process at 1600℃ or lower in inert gas atmosphere. Both of these processes use a lot of time and high energy, but are essential and important for producing high-performance carbon fibers. Therefore, in recent years, an alternative stabilization technology by being assisted with various other energy sources such as plasma, electron beam and microwave which can shorten the process time and lower energy consumption has been studied. In this study, the PAN precursor was stabilized by using plasma treatment and heat treatment continuously. The morphology, structural changes, thermal and physical properties were analyzed using Field emission scanning electron microscopy(FE-SEM), X-ray diffraction(XRD), Fourier transform infrared(FT-IR), Thermogravimetric analysis(TGA) and Favimat.

• Journal of the Semiconductor & Display Technology
• /
• v.22 no.2
• /
• pp.133-137
• /
• 2023

This study the problem of deposition uniformity observed during Mist-CVD deposition experiments. The TRIZ's ADRIGE algorithm, a problem-solving technique, is utilized to systematically analyze the issue and propose solutions. Through problem and resource analysis, technical contradictions are identified regarding the precursor's volume and its path when it encounters the substrate. To resolve these contradictions, the concept of applying the principle of dimensional change to transform the precursor's three-dimensional path into a one-dimensional path is suggested. The chosen solution involves the design of an enhanced Mist-CVD system, which is evaluated for feasibility and analyzed using computational fluid dynamics. The analysis confirms that the deposition uniformity consistently follows a pattern and demonstrates an improvement in uniformity. The improved Mist-CVD equipment is validated through analysis, providing evidence of its feasibility and yielding satisfactory results.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.18 no.1
• /
• pp.50-55
• /
• 2008

AI-doped ZnO(AZO) thin films have been fabricated on glass substrate by sol-gel method, and the effect of Al precursors and post-annealing temperature on the characteristics of AZO thin films was investigated. The sol was prepared with zinc acetate, EtOH, MEA and Al precursors. In order to dope Al in ZnO, two types of aluminum nitrate and aluminum chloride were used as Al precursor. Zinc concentration was 0.5 mol/l and the content of Al precursor was 1 at% of Zn in the sol. The sol was spin-coated on glass substrate, and the coated films were annealed at 550ue for 2 hand were post-annealed at temperature ranges of $300{\sim}500^{\circ}C$ for 2 h in reducing atmosphere ($N_2/H_2$= 9/1). Structural, electrical and optical propertis of the fabricated AZO thin films were analyzed by XRD, FE-SEM, AFM, hall effect measurement system and UV-visible spectroscopy. Optical and electrical properties of AZO thin films prepared with aluminum nitrate as Al precursor were better than those of films prepared with aluminum chloride. The electrical resistivity and the optical transmittance of films decreased with increasing post-annealing temperatures. The minimum electrical resistivity of $2{\times}10^{-3}$ and the maximum optical transmittance of 91% were obtained for the AZO thin films post-annealed at $550^{\circ}C\;and\;300^{\circ}C$, respectively.

• Current Photovoltaic Research
• /
• v.2 no.4
• /
• pp.177-181
• /
• 2014

$Cu_2ZnSn(S_xSe_{1-x})_4$ (CZTSSe) absorber thin films were prepared on Mo coated soda lime glass substrates by sulfo-selenization of sputtered stacked Zn-Sn-Cu precursor thin films. The Zn-Sn-Cu precursor thin films were sulfo-selenized inside a graphite box containing S and Se powder using rapid thermal processing furnace at $540^{\circ}C$ in Ar atmosphere with pre-treatment at $300^{\circ}C$. The effect of different S/Se ratio on the structural, compositional, morphological and electrical properties of the CZTSSe thin films were studied using XRD (X-ray diffraction), XRF (X-ray fluorescence analysis), FE-SEM (field-emission scanning electron microscopy), respectively. The XRD, FE-SEM, XRF results indicated that the properties of sulfo-selenized CZTSSe thin films were strongly related to the S/Se composition ratio. In particular, the CZTS thin film solar cells with S/(S+Se)=0.25 shows best conversion efficiency of 4.6% ($V_{oc}$ : 348 mV, $J_{sc}$ : $26.71mA/cm^2$, FF : 50%, and active area : $0.31cm^2$). Further detailed analysis and discussion for effect of S/Se composition ratio on the properties CZTSSe thin films will be discussed.

• Reproductive and Developmental Biology
• /
• v.36 no.2
• /
• pp.121-131
• /
• 2012

After spermatogenesis, spermatozoa come in contact with fluids in the epididymis where they mature. During ejaculation, spermatozoa are mixed with secretions from prostate gland, vesicular glands, and bulbourethral glands. During natural mating, seminal plasma is deposited in the female reproductive tract eliciting various physiological and immunological responses. With the advances in proteomics, the components of seminal plasma have been identified and the information may be valuable in identifying markers for fertility. Components of seminal plasma that affect fertility have been discovered and the mechanism of action of these factors has been determined. The objective of this study was to determine the specific seminal plasma proteins from Korean native cattle, Hanwoo, and Korean native brindle cattle (KNBC) with the long term goal of improving fertilization rate. After SDS-PAGE and 2-dimensional gel electrophoresis, proteins were identified by Q-ToF analysis. They include plasma serine protease inhibitor precursor and platelet-activating factor acetylhydrolase after SDS-PAGE. Number and density of the spots in 2-dimensional gels were higher in KNBC than Hanwoo. Proteins identified from the paired spots of both breeds include chain A, bull seminal plasma PDC-109 Fibronectin Type II module, BSP-30 kDa precursor, and Spermadhesin Z13 or its precursor. Interestingly, some proteins were identified from multiple spots. The functional differences of these diverse forms of the proteins may require further studies. With their previously reported roles in sperm capacitation by these proteins, the studies on the mechanism of action, ligand interaction and the variation in the genome may help improving fertility in cattle.

• Membrane Journal
• /
• v.29 no.5
• /
• pp.246-251
• /
• 2019

Facilitated transport membranes using silver nanoparticles as carriers for olefin/paraffin separation have been interested. $AgBF_4$ has been used as a precursor of silver nanoparticles in previous studies. However, relatively expensive $AgBF_4$ is not suitable for commercialization, and thus, PEBAX-5513/AgNPs (precursor: $AgClO_4$)/7,7,8,8-tetracyanoquinodimethane (TCNQ) composite membranes were prepared using silver nanopaticles with relatively inexpensive $AgClO_4$ precursors. Composite membranes of various compositions were prepared for PEBAX-5513/AgNPs/TCNQ composites, but no separation performance was observed. As a result of FT-IR analysis, it was confirmed that silver nanoparticles were formed in the PEBAX-5513 polymer and the surface of Ag nanoparticles was polarized by TCNQ, but the formed silver nanoparticles were not stabilized. From these results, it was concluded that the anion of the precursor plays an important role in the olefin/paraffin separation.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.6
• /
• pp.1993-1996
• /
• 2011

The vibronically well-resolved emission spectrum was recorded from the corona discharge of precursor 2,3,4-trifluorotoluene in a corona excited supersonic expansion with a pinhole-type glass nozzle using a long-path monochromator in the visible region. From the analysis of the observed spectrum, we found the evidence of the presence of the difluorobenzyl radicals in the corona discharge of the precursor. A possible mechanism is proposed for the formation of difluorobenzyl radicals in the gas phase on the basis of the observed emission intensity of the difluorobenzyl radicals produced.

• Journal of the Korean Applied Science and Technology
• /
• v.22 no.3
• /
• pp.228-233
• /
• 2005

Langmuir-Blodgett(LB) technique can speak the best candidate of the future molecular electronic devices. But, precursor as molecular ultrathin film devices require the bulk property that are influenced by the molecular orientation. So, this device is one of current interest in molecular electronic device development of new materials. In this study, quantitative evaluation of molecular orientation in LB films of polyamic acid alkylamine salt was performed analysis experiment comparing the absorption or transmission intensity of the FT-IR spectrometer and reflection or absorption spectra with UV-visible absorption spectra. It could find that the polar angle(${\theta}$) of the dipole moment appears in about $68^{\circ}$ and the tilting angle of the alkyl chain is about $11.5^{\circ}$.