• Journal of the Korean Chemical Society
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• v.17 no.2
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• pp.115-121
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• 1973

Crystalline products were obtained when$TiCl_4$ was reacted in dichloromethane with acetic, propionic, crotonic, benzoic, furoic and salicylic acids. Chemical analysis has shown that these were all dichlorodicarboxylatotitanium (IV). Cryoscopy of dichlorodipropionatotitanium (IV) indicated the carboxylato-complexes are dimeric. In the IR spectra of these complexes two strong bands both assigned to asymmetric carbonyl stretching vibration have been observed in the region$1500 - 1700cm^{-1}$ and the NMR spectrum of dichlorodipropionatotitanium (IV) has also shown two triplets and two quartets, which indicate that there are two chemically unequivalent carboxylato-ligands in the dimer $[TiCl_2(OOCR)_2]_2$. Their molecular structure was proposed to be bis-carboxo-bridged dimer.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.160-160
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• 2010

테라헤르츠 소스로 저온 InGaAs를 대체하기 위해 저온에서 성장한 $In_{0.64}Al_{0.36}Sb$의 성장 온도에 따른 광학적 photoluminescence (PL)과 time-resolved PL (TRPL) 측정을 이용하여 분석하였다. 또한 Be 도핑 농도에 따른 p형 $In_{0.64}Al_{0.36}Sb$의 PL과 TRPL 특성을 undoped $In_{0.64}Al_{0.36}Sb$와 Si-doped $In_{0.64}Al_{0.36}Sb$ 결과와 비교 분석하였다. 본 연구에 사용한 시료는 분자선 엑피탁시 (molecular beam epitaxy)법으로 GaAs 기판 위에 $In_{0.64}Al_{0.36}Sb$을 다양한 성장온도에서 ${\sim}3.7\;{\mu}m$두께 성장하였다. $In_{0.64}Al_{0.36}Sb$의 성장온도는 $400^{\circ}C$ 에서 $460^{\circ}C$까지 변화시키며 성장하였으며, Si과 Be 도핑한 $In_{0.64}Al_{0.36}Sb$ 시료는 약 $420^{\circ}C$에서 성장하였다. 모든 시료의 PL 피크는 ~1450 nm 근처에서 나타나며 단파장 영역에 shoulder 피크가 나타났다. 그러나 가장 낮은 온도 $400^{\circ}C$에서 성장한 시료는 1400 nm에서 1600 nm에 걸쳐 매우 넓은 피크가 측정되었다. PL 세기는 $450^{\circ}C$ 에서 성장한 시료가 가장 강하게 나타났으며, $435^{\circ}C$에서 성장한 시료의 PL 세기가 가장 약하게 나타났다. 방출파장에 따른 PL 소멸곡선을 측정하였으며 double exponential function을 이용하여 운반자 수명시간을 계산하였다. 운반자 수명시간은 빠른 소멸성분 $\tau_1$과 느린 소멸성분 $\tau_2$가 존재하고 빠른 성분 $\tau_1$의 PL 진폭이 약 80%로 느린 성분 $\tau_2$보다 우세하게 나타났다. 각 PL 피크에서의 운반자 수명시간 $\tau_1$은 ~1 ns로 성장온도에 따른 변화는 관찰되지 않았다. 또한 방출파장이 1400 nm에서 1480 nm까지 PL 피크 근처에서 운반자 수명시간은 거의 일정하게 나타났다. Be-doped 시료의 PL 피크는 1236 nm에서 나타나며, Si-doped 시료는 1288 nm, undoped 시료는 1430 nm에서 PL 피크가 측정되었다. PL 피크에서 PL 소멸곡선은 Be-doped 시료가 가장 빨리 감소하였으며, Si-doped 시료가 가장 길게 나타났다. 이러한 결과로부터 $In_{0.64}Al_{0.36}Sb$의 광학적 특성은 성장 온도, dopant type, 도핑 농도에 따라 변화하는 것을 확인하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.312-312
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• 2011

초고진공 장치 내에서 질량분석기와 티타늄 증착기를 이용하여 IRMOF-3에 증착된 티타늄과 수소 간의 흡착 특성을 TPD (Temperature Programmed Desorption)을 통하여 연구하였다. 티타늄을 흡착시키지 않은 순수한 IRMOF-3에 35K에서 주입한 중수소에 대한 TPD 데이터에서는 중수소가 저온 장치에 물리흡착된 약 50K에서의 작은 피크 이외에는 다른 흡착 특성을 보이지 않는다. 하지만 티타늄 2ML (Monolayer)를 흡착 시킨 IRMOF-3의 TPD 데이터에서는 약 60K와 95K에서의 두 피크가 보인다. 이는 분산된 티타늄과 중수소 사이에는 0.16eV와 0.25eV의 결합에너지를 가지는 두 가지의 다른 결합이 있다는 사실을 보여준다. 그리고 40K~110K에서 수소와 HD는 나오지 않고, 중수소만 나온 점은 주입한 중수소가 IRMOF-3에 분산된 티타늄에 쿠바스 상호작용에 의하여 분자상태로 화학 흡착되어 있을 것이라는 증거가 된다.

• Journal of Sericultural and Entomological Science
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• v.45 no.1
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• pp.58-65
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• 2003

This study was carried out to investigate the characteristics of the soluble sericins after degumming and after hydrolysis of insoluble sericin with various enzymes. Physical and chemical characteristics of the soluble sericins were also studied and pack test was conducted. Electro donating ability of the various sericins became higher as high＞low＞KP＞PP＞PA. In FT-IR analysis, the band of insoluble sericin at 3,285cm$\^$-1/ was shifted to the lower wavelengths in soluble sericins. The intensity of the amide II band was reduced and shifted to lower wavelengths as a result of hydrolysis. In DSC analysis, all sericins showed endothermic peaks around 200$^{\circ}C$ and insoluble sericin showed another peak at 250$^{\circ}C$. The endothermic peak of the insoluble sericin was found at higher temperature compared with those of the soluble sericins which showed at 300$^{\circ}C$. Whiteness of the various sericins became higher as low＞high＞PP＞PA＞PK＞IN and yellowness were PK＞PA＞PP＞low＞high. In pack test, the skin packed with the non-woven fabric treated with the various sericins was more smooth and less oily.

• Korean Journal of Food Science and Technology
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• v.46 no.6
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• pp.716-722
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• 2014

Aminopeptidase-active fractions from crude extract of the hepatopancreas of a common squid (Todarodes pacificus) were obtained using acetone (AC; 30-40%) and ammonium sulfate precipitation (AS; 60-70% saturation), anion exchange (AE-II; 0.2 M NaCl) and gel filtration chromatography (GF-I; 30-50 kDa), respectively. The debittering capacity of GF-I fraction based on the aminopeptidase activity (89.2 U/mg), recovery (56.6%) and sensory evaluation (1.0) was better than that of other fractions. Release of amino acids increased as incubation time was increased, and the bitterness of the enzyme reaction mixtures decreased. Incubation with the GF-I fraction for 24 h resulted in the hydrolysis of several peptides, as revealed by reverse-phase HPLC profiles. Peaks 3, 5 and 6 showed the decreased area (%), whereas peaks 1, 2 and 4 showed the increased area. The GF-I fractions were found to be suitable for reducing bitterness in protein hydrolysates by catalyzing the hydrolysis of bitter peptides.

• Korean Journal of Food Science and Technology
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• v.40 no.4
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• pp.470-473
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• 2008

This study examined the enzymatic digestion, average molecular weight distribution and structural changes of Bombyx mori silk gland fibroin using gel penneation chromatography and nuclear magnetic resonance methods. The pure-separation of calcium chloride-treated fibroin hydrolysates was carried out by gel filtration chromatography. Also, the effects of fibroin's enzymatic hydrolysis were investigated using an edible enzyme. The average molecular weight of three hydrolysate samples (silk gland fibroin (SF), SF-calcium chloride (SFC), and SFC-enzyme) were measured to compare their characteristics. The molecular weights of SF, SFC, and SFC-enzyme were approximately 108,000, 65,000, and 1,000 Da, respectively. Finally, we determined the structural characteristic changes of the different enzymatically digested samples by $^{13}C$ nuclear magnetic resonance methods. For the enzymatically digested fibroin, the glycine $^{13}C^{\alpha}$ resonance indicated that the amino acid was dramatically changed and/or separated out; however, this was not shown for the normal Bombyx mori silk gland fibroin.

• FOCUS: LIFE SCIENCE
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• no.1
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• pp.9.1-9.5
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• 2024

Method development for complex low molecular mass (LMM) samples using reversed-phase (RP) separation conditions presents significant challenges due to the presence of many unknown analytes over wide concentration ranges. This guide aims to optimize method parameters-column length (L), temperature (T), flow rate (F), and final mobile phase conditions (Øfinal)-to maximize separation peak capacity. Validated by prior research, this protocol benefits laboratories dealing with metabolomics, natural products, and contaminant screening. This practical guide provides a structured approach to maximizing peak capacity for complex LMM separations. It complements computational optimization strategies and offers a step-by-step method development process. The Snyder-Dolan test is highlighted as essential for determining the need for gradient or isocratic elution and guiding column length decisions. The decision tree framework helps analysts prioritize variable optimization to develop effective separation methods for complex samples.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.159-159
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• 2010

본 논문은 테라헤르츠 소스로 저온 InGaAs를 대체하기 위한 저온 $In_{0.64}Al_{0.36}Sb$의 실리콘(Si) 도핑 농도에 따른 광학적 특성 변화를 photoluminescence (PL)과 time-resolved PL (TRPL) 측정을 이용하여 분석하였다. $In_{0.64}Al_{0.36}Sb$ 시료는 분자선 엑피탁시 (molecular beam epitaxy)법으로 GaAs 기판 위에 약 $420^{\circ}C$에서 $3.7\;{\mu}m$ 두께 성장하였다. Si은 $In_{0.64}Al_{0.36}Sb$ 시료에서 도핑 농도가 낮을 때는 어셉터(acceptor)로 작용하다가 도핑 농도가 증가함에 따라 도너(donor)로 작용하였다. 본 연구에 사용한 $In_{0.64}Al_{0.36}Sb$ 시료의 Si 도핑 농도는 $4.5{\times}10^{16}\;cm^{-3}$ (n형), $4{\times}10^{16}\;cm^{-3}$ (n형), $8{\times}10^{15}\;cm^{-3}$ (n형), $1{\times}10^{15}\;cm^{-3}$ (p형), $4{\times}10^{14}\;cm^{-3}$ (p형)인 다섯 개의 시료를 사용하였다. Si 도핑한 시료의 PL 피크는 undoped 시료보다 약 100-200 nm 단파장에서 나타나고 PL 세기도 크게 증가하였다. 그러나 Si 도핑 농도가 가장 낮은 n형과 p형 시료의 PL 피크가 가장 짧은 파장 (높은 에너지)에 나타나고 도핑 농도가 증가함에 따라 장파장으로 이동함을 보였다. n형 시료의 도핑 농도가 $8{\times}10^{15}\;cm^{-3}$에서 $4.5{\times}10^{16}\;cm^{-3}$로 증가하였을 때 PL 피크는 1232 nm에서 1288 nm까지 장파장쪽으로 이동하였으며, p형 시료는 도핑 농도가 $4{\times}10^{14}\;cm^{-3}$에서 $1{\times}10^{15}\;cm^{-3}$로 증가하였을 때 PL 피크가 1248 nm에서 1314 nm로 이동함을 보였다. 또한 시료 온도에 따른 PL 결과는 온도가 증가함에 따라 PL 피크는 장파장으로 이동하면서 PL 세기는 급격하게 감소하고 약 100 - 150 K에서 소멸하였다. 그러나 ~1500 nm 이상 장파장 영역에 매우 넓은 새로운 피크가 나타났으며 온도가 증가함에 따라 PL 세기가 증가함을 확인하였다. Si 도핑 농도에 따른 운반자 수명시간 변화를 TRPL을 이용하여 측정하였다. 운반자 수명시간은 double exponential function을 이용하여 얻었다. Si 도핑 시료의 운반자 수명시간이 undoped 시료에 비해 매우 길게 나타났으며, Si 도핑 시료에서는 p형 시료들보다 n형 시료들의 운반자 수명시간이 길게 나타났다. PL 방출파장에 따른 운반자 수명시간은 Si 도핑 농도에 따라 다르게 나타났다. 이러한 PL과 TRPL 결과로부터 $In_{0.64}Al_{0.36}Sb$의 발광 특성 및 운반자 동역학은 Si 도핑에 크게 영향을 받는다는 것을 확인하였다.

• Journal of the Korean Applied Science and Technology
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• v.37 no.5
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• pp.1323-1329
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• 2020

To characterize the molecular structure of PhE-gal synthesized using Escherichia coli 𝛽-gal, NMR (¹H- and ¹³C-) spectroscopy and mass spectrometry of PhE-gal were conducted. ¹H NMR spectrum of PhE-gal showed multiple peaks corresponding to the galactosyl group, which is an evidence of galactosylation on 2-phenylethanol (PhE). Downfield proton peaks at 𝛿_H 7.30~7.21 ppm showed the presence of aromatic protons of PhE as well as benzyl CH₂ protons at 𝛿_H 2.88 ppm. Up field proton peaks at 𝛿_H 4.31 ppm, 4.07 ppm and multiple peaks from 𝛿_H 3.86~3.38 ppm are indicative of galactocylation on PhE. ¹³C NMR spectrum revealed the presence of 12 carbons suggestive of PhE-gal. Among 12 carbon peaks from PhE-gal, the four peaks at 138.7, 129.0, 128.6 and 126.5 were assigned aromatic carbons in the phenyl ring. Three peaks at 129.0, 128.6 and 126.5 showed high intensities, indicating CH aromatic carbons. ¹³C NMR data of PhE-gal showed 6 monosaccharide peaks from galactose and 2 peaks from aliphatic chain of PhE, indicating that PhE-gal was galactosyl PhE. The mass value (sodium adduct ion of PhE-gal, m/z = 307.1181) from mass spectrometry analysis of PhE-gal, and ¹H and ¹³C NMR spectral data were in good agreement with the expecting structure of PhE-gal. We are expecting that through future study it will eventually be able to develop a new additive with low cytotoxicity.

• Journal of the Korean Applied Science and Technology
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• v.38 no.3
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• pp.824-831
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• 2021

1, 2-Octanediol galactoside (OD-gal) has been synthesized from 1, 2-octanediol (OD), as a safer cosmetic preservative, using recombinant Escherichia coli β-galactosidase (β-gal). To confirm the molecular structure of synthesized OD-gal, mass spectrometry and NMR (¹H- and ¹³C-) spectroscopy of OD-gal were carried out. In the reaction mixture, a sodium adduct ion of OD-gal (m/z=331.1732) was identified using mass spectrometry analysis. In addition, ¹H NMR spectrum of OD-gal showed multiple peaks corresponding to the galactosyl group, which is evidence of galactosylation on OD. Downfield proton peaks at δ_H 4.39 ppm and multiple peaks from δ_H 3.98~3.55 ppm were indicative of galactosylation on OD. Up field proton peaks at δ_H 1.52~1.26 ppm and 0.89 ppm showed the presence of CH₂ and CH₃ protons of OD. ¹³C NMR spectrum revealed the presence of 24 carbons suggestive of α- and β-anomers of OD-gal. Among 14 carbon peaks from each anomer, the 4 peaks at δ_C 31.4, 29.0, 22.3, and 13.7 ppm were assigned to be overlapped showing only 24 peaks out of a total of 28 peaks. The mass value from mass spectrometry analysis of OD-gal, and ¹H and ¹³C NMR spectral data were in good agreement with the expecting structure of OD-gal. Finally, we identified a galactose molecule from the hydrolysate of OD-gal using β-gal. We are expecting that through future study it will eventually be able to develop a safe cosmetic preservative.