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Determination of panthenol, cholecalciferol and tocopherol in cosmetic products by gas chromatography-mass spectrometry in SIM mode

  • Hye-Jin Jeong;Myo
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.22 no.2
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    • pp.153-160
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    • 1996
  • A novel simple method to detect vitamins in cosmetic products by gas chromatography-mass spectrometry(GC-MS) has been developed. Three vitamins(panthenol, cholecalciferol and tocopherol) were used for this study. Vitamins were prepared by dissolving in tetrahydrofuran(THF), and silylated with bis-trimethylsilyltrifluoroacetamide-trichloromethylsilane(BSTFA). Silated vitamins were separated on a fuses-silica capillary column coated with DB-5. The identification of each vitamin was accomplished by retention time and mass spectrum library search with a computer, and the quantitation was made in the selected-ion monitoring(SIM) mode of GC-MS. SIM mode had given sensitivity to determine 50pg of panthenol, 285pg of cholecalciferol and 130pg of tocopherol. Linearity was maintained over the range 0.005-0.20% for each vitamin. Each cosmetic product(i.e. hair tonic and lotion) was found to contain amounts of the vitamins. This method was sensitive and gave 77.5-99.9% recovery of each vitamin from these cosmetic products. From these results, we concluded that silylation with BSTFA followed by GC-MS analysis allows the simple, covenient and exact determination of panthenol, cholecalciferol and tocopherol.

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A Simple Method for Determining Focal Distances Using Talbot Self-Images

  • Spires, Oliver;Sasian, Jose;Lee, Sukmock
    • Journal of the Optical Society of Korea
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    • v.19 no.6
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    • pp.638-642
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    • 2015
  • We present a simple method to determine the focal distances of lenses with the Talbot self-images. This method uses only one grating, and a priori knowledge of the period of the grating is replaced with a linear relation between the (de)magnified periods of the Talbot images and the lens-to-grating distance. A thick lens whose effective focal length is 500 mm was used to validate the method, and the focal distance of the converging beam was determined with the difference of 0.15% for the nominal focal distance of 521.9 mm. The determined period of the grating with the difference of 0.2% also supports the validation.

A Simple EDTA Titration Method for the Determination of Lead in Monazite (모나자이트 중의 납 정량을 위한 신속한 EDTA 적정법)

  • Chul Lee;Won Ji Cho
    • Journal of the Korean Chemical Society
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    • v.13 no.4
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    • pp.313-316
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    • 1969
  • In this paper a simple and rapid method is described for the determination of lead in monazite. A monazite sample was dissolved with hot concentrated sulfuric acid and diluted to 200 ml with distilled water. Lead is quatitatively separated by coprecipitating with strontium. Lead-strontium sulfate is dissolved in 3N NaOH soluion. An excess Zn-EDTA is added. The remaining zinc ion is titrated with standard 0.01 M EDTA solution using xylenol orange as indicator at pH 5 in the presence of KCN and acetyl acetone as masking agents.

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Isolation and Determination of Alkaloids in Coptis Rhizome by Forming Complex (착체 생성에 의한 황련 알칼로이드의 분리 및 정량)

  • 임소연;김대근;신태용;임종필;엄동옥
    • YAKHAK HOEJI
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    • v.46 no.4
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    • pp.226-230
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    • 2002
  • The Coptis Rhizome is known for containing a number of isoquinoline type alkaloids. Berberine, coptisine and palmatine are the major constituents of alkaloids. The alkaloids were isolated and determined by forming complex from Coptis japonica (Ranunculaceae). For the determination of these alkaloids, a new spectrophotometric method was developed with a simple and selective sample clean-up using thiocyanatocobaltate[II] complex ion. The absorbance of alkaloidal complex in l,2-dichloroethane solution was measured at 625 nm. A calibration curve for the alkaloids isolated from Coptis Rhizome was linear over the concentration range of 0.2-0.3 mg/mι. The method proved to be rapid, simple and reliable for the isolation and the determination of the alkaloids in Coptis Rhizome.

Fabrication of Simple White OLED with High Color Temperature for Medical Display Applications

  • Sung, Chang-Je;Kim, Jun-Jung;Lee, Jae-Man;Choi, Hong-Seok;Han, Chang-Wook;Lee, Nam-Yang;Ahn, Byung-Chul
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.489-492
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    • 2009
  • We report white OLED with high color temperature based on simple stacked structure for medical display applications. White OLED was fabricated with two emitting materials of fluorescent blue dopant and phosphorescent yellow dopant. We achieved luminance efficiency of 16.2cd/A and CIE color coordinates of (0.305, 0.317) at 10mA/$cm^2$. In particular, the correlated color temperature was higher than 7,000K, enough for display applications.

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A simple plane-strain solution for functionally graded multilayered isotropic cylinders

  • Pan, E.;Roy, A.K.
    • Structural Engineering and Mechanics
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    • v.24 no.6
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    • pp.727-740
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    • 2006
  • A simple plane-strain solution is derived in this paper for the functionally graded multilayered isotropic elastic cylinder under static deformation. The solution is obtained using method of separation of variables and is expressed in terms of the summation of the Fourier series in the circumferential direction. While the solution for order n = 0 corresponds to the axisymmetric deformation, that for n = 2 includes the special deformation frequently utilized in the upper and lower bounds analysis. Numerical results for a three-phase cylinder with a middle functionally graded layer are presented for both axisymmetric (n = 0) and general (n = 2) deformations, under either the traction or displacement boundary conditions on the surface of the layered cylinder. The solution to the general deformation case (n = 2) is further utilized for the first time to find the upper and lower bounds of the effective shear modulus of the layered cylinder with a functionally graded middle layer. These results could be useful in the future study of cylindrical composites where FGMs and/or multilayers are involved.

A Piezoelectric Energy Harvester with High Efficiency and Low Circuit Complexity

  • Do, Xuan-Dien;Nguyen, Huy-Hieu;Han, Seok-Kyun;Ha, Dong Sam;Lee, Sang-Gug
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.15 no.3
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    • pp.319-325
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    • 2015
  • This paper presents an efficient vibration energy harvester with a piezoelectric (PE) cantilever. The proposed PE energy harvester increases the efficiency through minimization of hardware complexity and hence reduction of power dissipation of the circuit. Two key features of the proposed energy harvester are (i) incorporation synchronized switches with a simple control circuit, and (ii) a feed-forward buck converter with a simple control circuit. The chip was fabricated in $0.18{\mu}m$ CMOS processing technology, and the measured results indicate that the proposed rectifier achieves the efficiency of 77%. The core area of the chip is 0.2 mm2.

Asymptotic Expansion of the Distribution of a Studentized Test Statistic for the Slope Parameter in a Simple Linear Structural Relationship

  • Chang, Kyung;Dahm, P. Frederic
    • Journal of Korean Society for Quality Management
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    • v.21 no.1
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    • pp.171-180
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    • 1993
  • Variables, x and y are said to have a linear relation if $y={\beta}_0+{\beta}_1\;x$, and ${\beta}_0$ and ${\beta}_1$ are constants. The relationship is called a structural relationship if x has positive variance (i.e., x is not fixed) and only error-prone measurements of x and y can be obtained. This paper derives (to order $n^{+1/2}$) an approximate distribution of the Studentized test statistic for testing hypotheses about the slope parameter, ${\beta}_1$ in a simple linear structural model. A simulation study suggests our approximate distribution is more accurate approximation to the exact distributions of the Studentized statistic than is the limiting distribution.

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Residual displacement estimation of simple structures considering soil structure interaction

  • Aydemir, Muberra Eser;Aydemir, Cem
    • Earthquakes and Structures
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    • v.16 no.1
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    • pp.69-82
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    • 2019
  • As the residual displacement and/or drift demands are commonly used for seismic assessment of buildings, the estimation of these values play a very critical role through earthquake design philosophy. The residual displacement estimation of fixed base structures has been the topic of numerous researches up to now, but the effect of soil flexibility is almost always omitted. In this study, residual displacement demands are investigated for SDOF systems with period range of 0.1-3.0 s for near-field and far-field ground motions for both fixed and interacting cases. The elastoplastic model is used to represent non-degrading structures. Based on time history analyses, a new simple yet effective equation is proposed for residual displacement demand of any system whether fixed base or interacting as a function of structural period, lateral strength ratio and spectral displacement.

Photoresponse Properties of Reduced Graphene Oxide/n-silicon Heterojunction Fabricated by the Vacuum Filtration and Transfer Method

  • Du, Yonggang;Qiao, Liangxin;Xue, Dingyuan;Jia, Yulei
    • Current Optics and Photonics
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    • v.6 no.4
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    • pp.367-374
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    • 2022
  • A photodetector based on a reduced graphene oxide (RGO)/n-Si heterojunction with high responsivity, detectivity and fast response speed is presented. Here, we put forward a simple vacuum filtration method to prepare RGO film and transfer it onto an n-Si substrate to form an RGO/n-Si heterojunction. The experimental results show that the heterojunction has good rectification characteristics, and the response and recovery time are less than 0.31 s and 0.25 s, respectively. Under 470 nm light conditions at -2 V applied voltage, the responsivity and detectivity of the device are 65 mA/W and 4.02 × 1010 cmHz1/2W-1, respectively. The simple preparation process and good performance of the RGO/n-Si heterojunction make it a promising material for photoelectric detection, especially in the near-ultraviolet band.