• Bulletin of the Korean Chemical Society
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• 제19권9호
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• pp.934-942
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• 1998

$^13CO$ chemisorbed on platinum particles in L-zeolite has been investigated by static and magic angle spinning NMR spectroscopy. The representative spectra are composed of a broad asymmetric peak with a center of gravity at 230±30 ppm and a sharp symmetric peak at 124±2 ppm which is tentatively assigned to physisorbed $CO_2$, on inner walls of L-zeolite. Overall, the broad resonance component is similar to our previous results of highly dispersed (80-96%) CO/Pt/silica or CO/Pt/alumina samples, still showing metallic characters. The principal difference is in the first moment value. The broad peak in the spectra is assigned to CO linearly bound to Pt particles in the L-zeolites, and indicates a distribution of isotropic shifts from bonding site to bonding site. The NMR results reported here manifest that the Pt particles inside of the L-zeolites channels are not collectively the same with the ones supported on silica or alumina with similar dispersion in terms of Pt particle shape and/or ordering of Pt atoms in a particle. As a result, Pt particles of CO/Pt/L-zeolite were agglomerated accompanying CO desorption upon annealing. There were no definite changes in the NMR spectra due to differences of exchanged cations. Comparison of our observation on CO/Pt/L-zeolite with Sharma et al.'s reveals that even when the first moment, the linewidtb, and the relaxation times of the static spectra and the dispersion measured by chemisorption are similar, the properties of Pt particles can be dramatically different. Therefore, it is essential to take advantage of the strengths of several techniques together in order to interpret data reliably, especially for the highly dispersed samples.

• Bulletin of the Korean Chemical Society
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• 제15권11호
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• pp.990-996
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• 1994

New ferrocene-based chelate amines, $Fe[C_5H_4CH(Me)NMe_2]_2\;(3), \;Fe[C_5H-3(CH(Me)NMe_2)(PPh_2)-1,2]_2\;(4),\;(C_5H_5)Fe(C_5H_3(CH_2NMe_2)(CH(CN)NMe_2-1,2)\;(6),\;and\;(C_5H_5)Fe(C_5H_3(CH_2NMe_2)(CH(Me)NMe_2-1,2)$ (7) have been prepared. The reaction and the coordination chemistry of 4 and other related compounds (S,R)-(1-N,N-dimethylaminoethyl)-2-dicyclohexylphosphino)ferrocene (CPFA) and 1,1'-bis-(diphenylphosphino)ferrocene (BPPF) with $Rh_2(OAc)_4(MeOH)_2$ were investigated. The reaction of the chiral ligand (S,R)-CPFA forms a complex of the type (${\eta}^1$-(S,R)-CPFA-P)$_2Rh_2(OAc)_4$ (8) in which the ligand is coordinated to both rhodium centers in a monodentate fashion through phosphorus. In contrast, the bisphosphine analogues such as BPPF and 4 afford chelate complexes of the type (${\eta}^2-PP)Rh_2(OAc)_4$ (9 & 10) where both ligands act as a chelate bidentate to a single rhodium atom. All these complexes were characterized by microanalytical and spectroscopic techniques. In one case, the structure of 8 was determined by X-ray crystallography. Crystals are monoclinic, space group C2 (No. 5), with a=26.389 (3), b=12.942 (1), c=11.825 (1) A, ${\beta}$=111.22(1)$^{\circ}$, V=3964.7 (8) $A^3$, Z=4, and $D_{calc}$=1.58 g $cm^{-3}$. Two Rh(II) centers are bridged by four $AcO^-$ groups in the ${\eta}^1$ : ${\eta}^1$ mode across a Rh-Rh single bond, and octahedral coordination at Rh(1) and Rh(1') is completed by axially coordinating (S,R)-CPFA and a briding $AcO^-$, respectively.

• Bulletin of the Korean Chemical Society
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• 제15권5호
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• pp.379-386
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• 1994

Reactions of 1',2-bis(diphenylphosphino)-l-(N,N-dimethylaminomethyl)ferrocene (FcNPP) with $M(CO)_6$ (M=Cr, Mo, W) in the presence of TMNO (Trimethylamine oxide) in a stoichiometric ratio of 1 : 1.5 : 3.5 produced a series of Gp 6 metal carbonyl derivatives with a variety of coordination modes: M(CO)$_4({\eta}^2$-FcNPP-P,P) (M=Cr, Mo, W), $M(CO)_5({\eta}^1-FcNPP-P) (M=Mo, W)\;,\; M_2(CO)_9({\eta}^1\;,\;{\eta}^2-FcNPP-P,P,N) (M=Cr, Mo)\;,\;M_2(CO)_{10}({\eta}^1\;,\;{\eta}^1-FcNPP-P,P) (M=Cr, Mo, W)\;, and\;W(CO)_4({\eta}^2-FcNPP(O)-P,N)$. All these complexes were characterized by microanalytical and spectroscopic techniques. In one case, the structure of W(CO)$_4({\eta}^2$-FcNPP(O)-P,N) was determined by X-ray crystallography. Crystals are monocinic, space group P$2_{1/C}$, with a=10.147(2), b=19.902(3), c=19.821(4) ${\AA},\;{\beta}=96.88(2)^{\circ},\;V=3974(l){\AA}^3$, Z=4, and $D_{calc}=1.64 g cm^{-3}$. The geometry around the central tungsten metal is a distorted octahedron, with the nitrogen and phosphorus atoms being cis to each other. Some of these complexes exhibited catalytic activities in the allylic oxidation and epoxidation of cholesterly acetate. Other oxidation products were also formed with the different chemical yields and product distribution depending upon the ligand and the central metal.

• Bulletin of the Korean Chemical Society
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• 제14권5호
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• pp.561-567
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• 1993

The twelve macrocycle (L) complexes of cadmium(II) nitrate have been synthesized: $CdL(NO_3)_2$. All the complexes have been indentified by elemental analysis, electric conductivity measurements, IR and NMR spectroscopic techniques. The molar electric conductivities of the complexes in water and acetonitrile solvent were in the range of 236.8-296.1 $cm^2{\cdot}mol^{-1}{\cdot}ohm^{-1}$ at 25$^{\circ}$C. The characteristic peaks of macrocycles affected from Cd(II) were shifted to lower frequencies as compared with uncomplexed macrocycles. A complex with 1,4,8,11-tetrakis(methylacetato)-1,4,8,11-tetraaza cyclodecane (L4) exhibited two characteristic bands such as strong stretching (1646 $cm^{-1})$, and weaker symmetric stretching band (1384 $cm^{-1})$. NMR studies indicated that all nitrogen donor atoms of macrocycles have greater affinity to cadmium(II) metal ion than do the oxygen atoms. The $^{13}$C-resonance lines of methylene groups neighboring the donor atom such as N and S were shifted to a direction of high magnetic field and the order of chemical shifts were $L_1 < L_2 < L_3 < L_6 < L_4$. Also the chemical shifts values were larger than those of methylene groups bridgeheaded in side-armed groups. This result seems due to not only the strong interaction of Cd(Ⅱ) with nitrogen donors according to the HSAB theory, but weak interaction of Cd(Ⅱ) and COO- ions or sulfur which is enhanced by the flexible methylene spacing group in side-armed groups. Thus, each additional gem-methyl pairs of L_3, L_4\;and\; L_6$ macrocycles relative to $L_1, L_2,\;and\;L_5$ leads to an large enhancement in Cd(II) affinity. ^{13}C$-NMR spectrum of the complex with $L_{12}$ (1,5,9,13-tetracyclothiacyclohexadecane-3,11-diol) reveals the presence of two sets of three resonance lines, and intensities of the each resonance line have the ratio of 1 : 2 : 2. This molecular conformation is predicted as structure of tetragonal complex to be formed by coordinating two sulfur atoms and the other two sulfur atoms which is affected by OH-groups.

• 한국자원식물학회지
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• 제31권4호
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• pp.322-329
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• 2018

최근 식품의약품안전처에서 그동안 의약외품으로 분류되었던 '탈모 증상 완화' 관련 제품이 기능성 화장품의 범주에 포함됨에 따라서 관련 산업계에 큰 관심 중 하나라고 할 수 있다. 본 연구에서는 기존 의약품들의 한계점인 부작용의 위험률이 적으면서 탈모를 과학적으로 조절시켜줄 수 있는 객관적인 근거를 제시할 수 있는 천연물 유래 신소재를 발굴하고자, 오리나무 가지로부터 분리한 oregonin은 강력한 활성산소종 소거능을 가지며 탈모와 연관성이 높은 모유두 세포의 사멸을 명확하게 조절함을 확인하였다. 결론적으로 oregonin을 포함한 오리나무 추출물은 두피에서 발생한 활성산소를 강력하게 제거하는 효능을 기반으로 하여, 산화적 스트레스에 의한 모유두세포의 사멸 억제 및 조절을 통하여 탈모방지 효과를 기대할 수 있는 천연 탈모 방지 및 양모 신소재로서의 개발가능성이 있는 것으로 확인하였다.

• 농업과학연구
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• 제46권1호
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• pp.183-194
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• 2019

Adulteration of argan oil with some other cheaper oils with similar chemical compositions has resulted in increasing demands for authenticity assurance and quality control. Fast and simple analytical techniques are thus needed for authenticity analysis of high-priced argan oil. Raman spectroscopy is a potent technique and has been extensively used for quality control and safety determination for food products In this study, Raman spectroscopy in combination with a net analyte signal (NAS)-based methodology, i.e., hybrid linear analysis method developed by Goicoechea and Olivieri in 1999 (HLA/GO), was used to predict the different concentrations of olive oil (0 - 20%) added to argan oil. Raman spectra of 90 samples were collected in a spectral range of $400-400cm^{-1}$, and calibration and validation sets were designed to evaluate the performance of the multivariate method. The results revealed a high coefficient of determination ($R^2$) value of 0.98 and a low root-mean-square error (RMSE) value of 0.41% for the calibration set, and an $R^2$ of 0.97 and RMSE of 0.36% for the validation set. Additionally, the figures of merit such as sensitivity, selectivity, limit of detection, and limit of quantification were used for further validation. The high $R^2$ and low RMSE values validate the detection ability and accuracy of the developed method and demonstrate its potential for quantitative determination of oil adulteration.

• 한국재료학회지
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• 제29권8호
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• pp.469-476
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• 2019

A lead-free bulk ceramic having a chemical formula $Ba_{0.8}Ca_{0.2}(Ti_{0.8}Zr_{0.1}Ce_{0.1})O_3$ (further termed as BCTZCO) is synthesized using mixed oxide route. The structural, dielectric, impedance, and conductivity properties, as well as the modulus of the synthesized sample are discussed in the present work. Analysis of X-ray diffraction data obtained at room temperature reveals the existence of some impurity phases. The natural surface morphology shows close packing of grains with few voids. Attempts have been made to study the (a) effect of microstructures containing grains, grain boundaries, and electrodes on impedance and capacitive characteristics, (b) relationship between properties and crystal structure, and (c) nature of the relaxation mechanism of the prepared samples. The relationship between the structure and physical properties is established. The frequency and temperature dependence of the dielectric properties reveal that this complex system has a high dielectric constant and low tangent loss. An analysis of impedance and related parameters illuminates the contributions of grains. The activation energy is determined for only the high temperature region in the temperature dependent AC conductivity graph. Deviation from the Debye behavior is seen in the Nyquist plot at different temperatures. The relaxation mechanism and the electrical transport properties in the sample are investigated with the help of various spectroscopic (i.e., dielectric, modulus, and impedance) techniques. This lead free sample will serve as a base for device engineering.

• 농업과학연구
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• 제49권3호
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• pp.495-510
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• 2022

In this study, fluorescence hyperspectral imaging (FHSI) was used for the rapid, non-destructive detection of fake, manmade eggs from real eggs. To identify fake eggs, protoporphyrin IX (PpIX)-a natural pigment present in real eggshells-was utilized as the main indicator due to its strong fluorescence emission effect. The fluorescence images of real and fake eggs were acquired using a line-scan-based FHSI system, and their fluorescence features were analyzed based on spectroscopic techniques. To improve the detection performance and accuracy, an optimal waveband combination was investigated with analysis of variance (ANOVA), and its fluorescence ratio images (588/645 nm) were created for visualization of the real eggs between two different egg groups. In addition, real and fake eggs were scanned using a one-waveband (645 nm) handheld fluorescence imager that can perform real-time scanning for on-site applications. Then, the results of the two methods were compared with one another. The outcome clearly shows that the newly developed FHSI system and the fluorescence handheld imager were both able to distinguish real eggs from fake eggs. Consequently, FHSI showed a better performance (clearer images) compared to the fluorescence handheld imager, and the outcome provided valuable information about the feasibility of using FHSI imaging with ANOVA for the discrimination of real and fake eggs.

• Journal of Ginseng Research
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• 제46권3호
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• pp.357-366
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• 2022

Background: Withania somnifera (Solanaceae), generally known as Indian ginseng, is a medicinal plant that is used in Ayurvedic practice for promoting health and longevity. This study aims to identify the bioactive metabolites from Indian ginseng and elucidate their structures. Methods: Withanolides were purified by chromatographic techniques, including HPLC coupled with LC/MS. Chemical structures of isolated withanolides were clarified by analyzing the spectroscopic data from 1D and 2D NMR, and HR-ESIMS experiment. Absolute configurations of the withanolides were established by the application of NMR chemical shifts and ECD calculations. Anti-adipogenic activities of isolates were evaluated using 3T3-L1 preadipocytes with Oil Red O staining and quantitative real-time PCR (qPCR). Results: Phytochemical examination of the roots of Indian ginseng afforded to the isolation of six withanolides (1-6), including three novel withanolides, withasilolides GeI (1-3). All the six compounds inhibited adipogenesis and suppressed the enlargement of lipid droplets, compared to those of the control. Additionally, the mRNA expression levels of Fabp4 and Adipsin, the adipocyte markers decreased noticeably following treatment with 25 µM of 1-6. The active compounds (1-6) also promoted lipid metabolism by upregulating the expression of the lipolytic genes HSL and ATGL and downregulating the expression of the lipogenic gene SREBP1. Conclusion: The results of our experimental studies suggest that the withasilolides identified herein have anti-adipogenic potential and can be considered for the development of therapeutic strategies against adipogenesis in obesity. Our study also provides a mechanistic rationale for using Indian ginseng as a potential therapeutic agent against obesity and related metabolic diseases.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1516-1516
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• 2001

During the recent years, wine analysis has played an increasing role due the health benefits of phenolic ingredients in red wine [1]. On the other hand there is the need to be able to distinguish between different wine varieties. Consumers want to know if a wine is an adulterated one or if it is based on the pure grape. Producers need to certificate their wines in order to ensure compliance with legal regulations. Up to now, the attempts to investigate the origin of wines were based on high-performance liquid chromatography (HPLC), gas chromatography (GC) and pyrolysis mass spectrometry (PMS) [l,2,3]. These methods need sample pretreatment, long analysis times and therefore lack of high sample throughput. In contradiction to these techniques using near infrared spectroscopy (NIRS), no sample pretreatment is necessary and the analysis time for one sample is only about 10 seconds. Hence, a near infrared spectroscopic method is presented that allows a fast classification of wine varieties in bottled red wines. For this, the spectra of 50 bottles of Cabernet Sauvignon, Lagrein and Sangiovese (Chianti) were recorded without any sample pretreatment over a wavelength range from 1000 to 2500 nm with a resolution of 12 cm$\^$-1/. 10 scans were used for an average spectrum. In order to yield best reproducibility, wines were thermostated at 23$^{\circ}C$ and a optical layer thickness of 3 mm was used. All recorded spectra were partitioned into a calibration and validation set (70% and 30%). Finally, a 3d scatter plot of the different investigated varieties allowed to distinguish between Cabernet Sauvignon, Lagrein and Sangiovese (Chianti). Considering the short analysis times this NRS-method will be an interesting tool for the quality control of wine verification and also for experienced sommeliers.