• Title/Summary/Keyword: Beta crystal

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Preparation and characterization of $Pb_2C_2O_4(NO_3)_2{\cdot}2H_2O$ ($Pb_2C_2O_4(NO_3)_2{\cdot}2H_2O$의 제조 및 특성평가)

  • 최희락
    • Journal of Ocean Engineering and Technology
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    • v.11 no.1
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    • pp.49-54
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    • 1997
  • On the precipitatiopn and ripening reaction of the precipitates from a lead nitrate and an oxalic acid dissolved in ethanol, a new crystalline phase was obtained, whose X-ray diffraction data have not previously been reported. The crystal system was determined to be monoclinic. The unit-cell parameters were refined to a =10.613(2)$\AA$, b =7.947(2))$\AA$, c =6.189(1)$\AA$, and $\beta$=104.48(2)$^{\circ}$.

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A study on the manufacture and dielectric of the polyvinylidene fluoride thin films through vapor deposition method (진공증착법을 이용한 PVDF박막의 제작과 유전 특성에 관한 연구)

  • Park, S.H.;Im, U.C.;Cho, K.S.;Lee, D.C.
    • Proceedings of the KIEE Conference
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    • 1995.11a
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    • pp.420-422
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    • 1995
  • PVDF (polyvinylidene fluoride) has at least from known crystalline structure ( ; they are referred to as the $\alpha$, $\beta$, $\gamma$ and $\alpha_p$ phase or forms II, I, III and $IV_p$). In this study, the manufactured PVDF thin films through vapor deposition method had for II ( ; the substrate temperature at 30$^{\circ}C$). The dielectric behavior of poly(vinylidene fluoride) is affected by orientation and crystal modification. The very high value of the dielectric constant for high temperature conditioned film is believed to be due to the orientation effect. The loss peak caused by molecular motion of the molecules in crystalline regions.

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Bacterial Hormone-Sensitive Lipases (bHSLs): Emerging Enzymes for Biotechnological Applications

  • Kim, T. Doohun
    • Journal of Microbiology and Biotechnology
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    • v.27 no.11
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    • pp.1907-1915
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    • 2017
  • Lipases are important enzymes with biotechnological applications in dairy, detergent, food, fine chemicals, and pharmaceutical industries. Specifically, hormone-sensitive lipase (HSL) is an intracellular lipase that can be stimulated by several hormones, such as catecholamine, glucagon, and adrenocorticotropic hormone. Bacterial hormone-sensitive lipases (bHSLs), which are homologous to the C-terminal domain of HSL, have ${\alpha}/{\beta}-hydrolase$ fold with a catalytic triad composed of His, Asp, and Ser. These bHSLs could be used for a wide variety of industrial applications because of their high activity, broad substrate specificity, and remarkable stability. In this review, the relationships among HSLs, the microbiological origins, the crystal structures, and the biotechnological properties of bHSLs are summarized.

Effect of bath conditions and pulse parameters on tin surface finish for microelectronic packaging applications

  • Sharma, Ashutosh;Jung, Do-hyun;Jung, Jae-pil
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2015.11a
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    • pp.232-233
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    • 2015
  • The effects of various bath conditions such as surfactant concentration, bath pH, bath temperature, agitation of bath; as well as pulse parameters such as cathodic current density, pulse duty cycle and frequency, on the grain size, surface finish, and appearance of the tin plated coatings have been investigated. The plating bath under investigation is an aqueous acidic solution composed of a mixture of $SnSO_4$, $H_2SO_4$, and a surfactant. The bath conductivity and pH are measured by a glass pH electrode. The microstructure of the coatings produced is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and surface profilometry. XRD analysis shows that the deposits consist of tetragonal ${\beta}$-Sn crystal structure irrespective of plating conditions. The mechanism involved in the morphology evolution in response to various parameters and conditions has also been discussed.

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Sintering Properties of Hydroxyapatite Derived from Tuna Bone

  • Park, Jin-Sam;Huh, Jeung-Soo;Kim, Hyung-Sun
    • Journal of the Korean Ceramic Society
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    • v.37 no.12
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    • pp.1131-1134
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    • 2000
  • Hydroxyapatite (HA) ceramic was prepared using tuna bone powders and was characterized on properties of sintered samples. The aim was to prepare dense and bulk HA sintered suitable for clinical applications. Thermal analysis, X-ray diffraction analysis, microscopic observation, and mechanical evaluation were applied to characterize sintered HA to find optimum processing condition. The major phase of sintered HA was observed up to 1300$\^{C}$ and $\beta$-TCP was observed as temperature increased. The density of sintered HA was increased up to 1350$\^{C}$ and decreased with further increasing temperature. The flexural strength of sintered HA at 1350$\^{C}$ showed 58 MPa as the highest value in this work. The results suggest that the crystal phase and transformation characteristics of HA prepared from tuna bone are the same as the behavior of HA powders made by chemical synthesis.

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Fabrication of CNT-Reinforced HAp Composites by Spark Plasma Sintering

  • Sarkar, Swapan Kumar;Youn, Min-Ho;Oh, Ik-Hyun;Lee, Byong-Taek
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.1082-1083
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    • 2006
  • Carbon nanotube (CNT) reinforced hydroxyapatite (HAp) composites were fabricated by using the spark plasma sintering process with surfactant modified CNT and HAp nano powder. Without the dependency on sintering temperature, the main crystal phase existed with the HAp phase although a few contents of ${\beta}-TCP$ (Tri calcium phosphate) phase were detected. The maximum fracture toughness, $(1.27\;MPa.m^{1/2})$ was obtained in the sample sintered at $1100^{\circ}C$ and on the fracture surface a typical intergranular fracture mode, as well as the pull-out pmhenomenon of CNT, was observed.

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Refinement of the structure of naproxen, (+)-6- methoxy-$\alpha$-methyl-2-naphthaleneacetic acid

  • Kim, Yang-Bae;Song, Hyun-June;Park, Il-Yeong
    • Archives of Pharmacal Research
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    • v.10 no.4
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    • pp.232-238
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    • 1987
  • The molecular structure of naproxen determined by X-ray diffraction technique was refine to the final R-value geing 0.042. The compound was recrystallized from ethanol solution in monoclinic crystal system, space group $P2_1$ , with Z = 2, a = 13.375(5) $\AA$, b = 5.793(2) $\AA$, c = 7.914 $\AA$, $\beta$=93.91(3)$\AA$ and $d_{obs}$ = 1.26, $d_{calc}$ = 1.25 g/cm$^{3}$. The structure was solved by direct method and refined by block diagonal least squares procedure for 747 relfections (F .leq. 6.sigma.(F)). The molecules are connected by two intermolecular OH--O type hydrogen bonds.

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Crystal Structure of PDZ Domains, Protein Interaction Modules

  • Park, Seong-Ho;Im, Young-Jun;Soyoung Yang;Kim, Eunjoon;Eom, Soo-Hyun
    • Proceedings of the Korean Biophysical Society Conference
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    • 2001.06a
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    • pp.21-21
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    • 2001
  • PDZ domains are molecular-recognition elements that mediate protein-protein interactions. The PDZ domain was discovered originally as a common motif present in three structurally related proteins: PSD-95 (postsynaptic density protein), Dlg (discs-large protein) and ZQ-1 (zonula occludens-1). The PDZ domain is globular domain, containing about 80-100 amino acids, and a conserved motif with two alpha helices and six beta strands. Most of them bind selectively to the C-termini of the interacting proteins at the complexes of signaling molecules and membrane associated receptors.(omitted)

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Crystal Structure of a Maltogenic Amylase: Insights into a Catalytic Versatility

  • Oh, Sang-Taek;Cha, Sun-Shin;Kim, Hyun-Ju;Kim, Tae-Jip;Cho, Hyun-Soo;Park, Kwan-Hwa;Oh, Byung-Ha
    • Proceedings of the Korean Biophysical Society Conference
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    • 1999.06a
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    • pp.35-35
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    • 1999
  • Amylases catalyze the hydrolysis of starch material and play central roles in carbohydrate metabolism. The structure and a size exclusion column chromatography proved that the enzyme is a dimer in solution. The N -terminal segment of the enzyme folds into a distinct domain and comprises the enzyme active site together with the central (${\alpha}$/ ${\beta}$)$\sub$8/ barrel of the adjacent subunit.(omitted)

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A Study on the Crystal Structure and Mechanical Properties of Isotactic Polypropylene (i-PP) Films (Isotactic Polypropylene (i-PP) film의 구조변화와 물성에 관한 연구)

  • Park, Myung-Soo;Kwon, Oh-Hyuk
    • Textile Coloration and Finishing
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    • v.9 no.6
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    • pp.18-25
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    • 1997
  • The change of crystalline structure and mechanical properties of i-PP films which had before isothermally annealed at various temperature and times have been studied. The following results were abtain The crystallinity and crystallite size of the samples showed increasing above the annealing temperature of 13$0^{\circ}C$ and these are equilibrated after an annealing time of 30min. When the crystalline form was at annealling condition were below 13$0^{\circ}C$, 2min, subsequently achieving an $\alpha$, $\beta$ mixing form and at 13$0^{\circ}C$, 10min, the crystalline form entered an $\alpha$ form transition. It is achieved a typical $\alpha$ form at 15$0^{\circ}C$. The value of T'm was increasing until 13$0^{\circ}C$ but it was not founded at 15$0^{\circ}C$. The slopes which represented crystalline form in an Avrami plot differed from each other within the range of this experiment.

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