• Journal of Pharmaceutical Investigation
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• 제35권2호
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• pp.123-127
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• 2005

An HPLC method was employed for the determination of ethambutol in human plasma. After addition of internal standard (IS, octylamine, $2\;{\mu}g/mL$) and alkalinization of the plasma with 5 M sodium hydroxide, the drug and IS were extracted into the mixture of chloroform and diethyl ether (40:60, v/v). Following a 15-min vortex-mixing and a 10min centrifugation, the organic phase was spiked with $100{\mu}L$ of phenylethylisocyanate $(2000{\mu}g/mL)$ for chemical derivatization, mixed for 5 min and evaporated to dryness under a stream of nitrogen. The residue was reconstituted with $100{\mu}L$ of mobile phase and $20{\mu}L$ was injected into C18 column with a mobile phase consisting of methanol:water (70:30, v/v). The samples were detected utilizing an ultraviolet detector at 200 nm. The method was specific and validated with a limit of $0.15\;{\mu}g/mL$. Intra- and inter-day precision and accuracy were acceptable for all quality control samples including the lower limit of quantification. The applicability of this method was demonstrated by analysis of human plasma after oral administration of a single 1200-mg dose to 20 healthy subjects. From the plasma ethambutol concentration vs. time curves, the mean AUC was $9.61{\pm}1.64\;{\mu}g{\cdot}hr/mL$ and Cmax of $2.68\;{\mu}g/mL$ reached 2.73 hr after administration. The mean biological half-life of ethambutol was $3.46{\pm}1.21$ hr. Based on the results, this simple and validated assay could readily be used in any pharmacokinetic studies using humans.

• 분석과학
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• 제33권1호
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• pp.11-22
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• 2020

When extracting semi-volatile components of herbal medicines using hot water vapor, some substances may react with water vapor or oxygen, and some volatile substances may be lost, when using an organic solvent extraction method has the disadvantage that it may contain a non-volatile material and residual organic solvent. In addition, it is inefficient to separate semi-volatile substances from herbal medicines into each single component and conduct biological activity research for each component to determine the effective ingredient, and some components may be lost in the separation process. In this study, semi-volatile substances evaporated under two pressure-reduced conditions in Chinese herbal medicines such as Cnidii Rhizoma, Aucklandiae Radix and Amomum Fructus were separated by cooling with liquid nitrogen. Those were analyzed by gas chromatography-mass spectrometry (GC-MS) to identify the components, and this method may be used to study biological activities at the cellular level. The substances separated under reduced pressure, essential oil obtained by simultaneous distillation extraction (SDE) method and substances by using solid phase micro-extraction (SPME) from Cnidii Rhizoma, Aucklandiae Radix and Amomum Fructus were analyzed by GC-MS. In the case of Cnidii Rhizoma and Aucklandiae Radix, there were some differences among the essential oil components obtained by SDE and those identified by low temperature capture (CT) and SPME method, these were believed to be produced by some volatiles reacting with water or oxygen at the boiling point temperature of water.

• 공업화학
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• 제31권3호
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• pp.317-322
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• 2020

수산화암모늄나이트레이트(HAN; NH₃OHNO₃)는 낮은 용융점과 증기압의 특성을 가지고 있고, 상대적으로 높은 산소균형을 이루고 있는 이온성 화합물이다. 본 연구에서는 높은 함량의 액상추진제를 제조하기 위한 산화제로 활용하기 위하여 이중용매를 적용하여 고체입자상으로 얻었다. 감압 하에서 액상의 HAN으로부터 수분을 증발시킨 후, 반용매로서 아세톤과 에탄올을 적용하여 추출한 입자상의 HAN에는 13.8 wt%의 수분이 포함되어 있었다. 아세톤을 단독으로 적용하였을 때, 합성수율은 질량기준으로 최대 88%이었고, TGA로 측정된 최대 함량은 86.2%, 분해온도는 160~205℃ 범위로 나타났다.

• Progress in Superconductivity
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• 제7권2호
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• pp.140-144
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• 2006

We fabricated the YBCO films on single crystal $LaAlO_3$ substrates via a metal organic deposition (MOD) process. In the process, $Y_2Ba_1Cu_1O_x$ and $Ba_3Cu_5O_8$ powders were dissolved in trifluoroacetic acid (TFA) followed by calcining and firing heat treatments. To evaluate the effects of the firing temperature on YBCO phase formation and critical properties, the films were fired at $750^{\circ}C,\;775^{\circ}C\;and\;800^{\circ}C$ after calcining at $430^{\cric}C$. Microstructure observation indicated that a crack-free surface formed and a strong biaxial texture was developed. The FWHM of out-of-plane texture was measured to be in the range of $4.3^{\cric}-7.0^{\circ}$ for all the films. When the YBCO film was fired at $775^{\cric}C$, it had the highest critical properties: 88.5 K of critical temperature and 16 A/cm-width of critical current ($1MA/cm^2$ as critical current density). On the other hand, those properties were degraded as firing at $750^{\circ}C\;and\;800^{\circ}C$. It is considered that the improved critical values are partly owing to dense and homogeneous microstructure, strong texture, and high oxygen content.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.73-73
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• 2011

We will report a few methods to improve the efficiency and stability in small molecule based organic solar cells, including the formation of bulk heterojunctions (BHJs) through alternative thermal deposition (ATD), the use of a micro-cavity structure and interface modifications. By ATD which is a simple modification of conventional thermal evaporation, the thicknesses of alternative donor and acceptor layers were precisely controlled down to 0.1 nm, which is critical to form BHJs. The formation of a BHJ in copper(II) phthalocyanine (CuPc) and fullerene (C60) systems was confirmed by AFM, GISAXS and absorption measurements. From analysis of the data, we found that the CuPc|C60 films fabricated by ATD were composed of the nanometer sized disk shaped CuPc nano grains and aggregated C60, which explains the phase separation of CuPc and C60. On the other hand, the co-deposited CuPc:C60 films did not show the existence of separated CuPc nano grains in the CuPc:C60 matrix. The OPV cells fabricated using the ATD method showed significantly enhanced power conversion efficiency compared to the co-deposited OPV cells under a same composition [1]. We will also present by numerical simulation that adoption of microcavity structure in the planar heterojunction can improve the short circuit current in single and tandem OSCs [2]. Interface modifications also allowed us to achieve high efficiency and high stability OSCs.

• 한국재료학회지
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• 제20권10호
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• pp.535-542
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• 2010

In this study, we used coal-based activated carbons and charcoal as startingmaterials, phenolic resin (PR) as a binder, and TOS as a titanium source to prepare $TiO_2$ combining spherical shaped activated carbon photocatalysts. The textural properties of the activated carbon photocatalysts (SACP) were characterized by specific surface area (BET), energy dispersive X-ray spectroscopy (XRD), scanning electron microscopy (SEM), iodine adsorption, strength intensity, and pressure drop. The photocatalytic activities of the SACPs were characterized by degradation of the organic dyes Methylene Blue (MB), Methylene Orange (MO), and Rhodamine B (Rh. B) and a chemical oxygen demand (COD) experiment. The surface properties are shown by SEM. The XRD patterns of the composites showed that the SACP composite contained a typical single, clear anatase phase. The EDX spectro for the elemental indentification showed the presence of C and O with Ti peaks. According to the results, the spherical activated carbon photocatalysts sample of AOP prepared with activated carbon formed the best spherical shape, a high BET surface area, iodine adsorption capability and strength value, and the lowest pressure drop, and the photocatalytic activity was better than samples prepared with charcoal. We compared the degradation effects among three kinds of dyes. MB solution degraded with the SACP is better than any other dye solutions.

• 한국전기전자재료학회논문지
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• 제21권12호
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• pp.1083-1089
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• 2008

We studied the dielectric characteristics of low-k SiOCH thin films by Ellipsometry. The SiOCH thin films were prepared by deposition of BTMSM precursors on p-Si wafer by CCP-PECVD method. The nano-porous structural organic/inorganic hybrid-type of SiOCH thin films correlated directly to the formation of low dielectrics close to pore(k=1). The structural groups including highly dense pores in SiOCH thin films originated the anisotropic geometry type of network structure directing to complex refractive characteristics of SiOCH single layer on the p-Si wafer. The linearly polarized beam of Xe-ramp in the range from 190 nm to 2100 nm introduced to the surface of SiOCH thin film, and the reflected beam was Elliptically polarized by complex refractive coefficients of SiOCH dipole groups. The amplitude variation $\Psi$ and phase variation $\Delta$ of the relative reflective coefficients between perpendicular and parallel components to the incident plane were measured by Ellipsometry. The complex optical constants n and k as well as the dielectric constant and thickness of SiOCH thin films were driven by the measured value of $\Psi$ and $\Delta$.

• 전자공학회논문지A
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• 제31A권10호
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• pp.79-86
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• 1994

Gain-guided broad-area single quantum well separate confinement heterostructure diode lasers have been fabricated from structures grown by metal organic vapor phase epitaxy. The active layer of the epi-structure is InGaAs emitting 962-965nm and the guiding layer GaAs. The channel width is fixed to 150${\mu}$m and the cavity length varys within the range of 300~800${\mu}$m. For uncoated LD's, the output power of 0.7W has been obtaained at a pulsed current level of 2A, which results about 60% external quantum efficiency. The threshold current density is 200A/cm$^{2}$ for the cavity lengths of 800.mu.m LD's. The stain effect upon the transparent current density has been observed. The internal quantum efficiency is expected to be 88% and the internal loss to be 18$cm^{-1}$. The beam divergence has been measured to be 7$^{\circ}$to lateral and 40$^{\circ}$to transverse direction. finally, 1.2W continuous-wave output power has been obtained at a current level of 2A for AR/HR coated LD's die-bonded on Cu heat-sink and cooled by TEC.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.690-693
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• 2003

Soft x-ray microscopy provides a unique set of capabilities in-between those of visible light and electron microscopy. It has long been recognized that nature provides a 'water window' spectral region between the K shell x-ray absorption edges of carbon (~290eV) and oxygen (~540eV), where organic materials show strong absorption and phase contrast, while water is relatively non-absorbing. This enables imaging of hydrated biological specimens that are several microns thick with high intrinsic contrast using x-rays with a wavelength of 2.3~4.4nm. Soft X-ray microscopy is therefore well suited to the study of specimens like single biological cells. The most direct advantage of X-ray microscope is their high spatial resolution when compared with visible light microscopes, combined with an ability to image hydrated specimens that are several microns with a minimum of preparation. Our study describes the conceptual design of soft x-ray microscope system based on a laser-based source for biomedical application with high resolution ($\leq$50nm) and short exposure time ($\leq$30sec).

• 한국결정성장학회지
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• 제10권3호
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• pp.205-210
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• 2000

초음파분무를 이용한 MOCVD법으로 강유전체 $PbTiO_3$박막을 Si(100) wafer와 ITO-coated glass위에 제조하였다 Si 기판 위에 증착된 박막으로부터, 출발원료의 농도비(Ti/Pb)가 1.2일 때, 단일 perovskite 상을 얻을 수 있었다. ITO-coated glass 위에 증착된 박막은 Si기판 위에 제조된 박막보다 박막의 성장속도가 더 빠르며, 기판온도를 $530^{\circ}C$부터 $570^{\circ}C$까지 증가시켰을 때, 결절성과 입자 크기의 증가에 의해 유전상수는 증가하였다. $570^{\circ}C$에서의 유전상수 및 유전손실 값은 각각 205, 0.016을 나타내었다. 기판온도가 $600^{\circ}C$ 이상인 경우, 유전상수가 감소되는 경향을 보였다.