• 제목/요약/키워드: Solid-state reaction

검색결과 847건 처리시간 0.026초

효소에 의한 우지의 가수분해 반응 (Enzymatic Hydrolysis of Beef Tallow)

  • 김인호;박태현
    • 한국미생물·생명공학회지
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    • 제19권4호
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    • pp.377-382
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    • 1991
  • 우지를 lipase에 의해 지방산과 글리세린으로 분해하는 반응을 액상 및 고상에서 수행하였다. 올리브유를 기질고 lipase OF 360(일본 메이토사 제품)의 특성을 조사한 결과 최적 pH는 6, 최적 온도는 $37^{\circ}C$이었다. 우지를 기질로 액상 효소반응을 수행한 결과는 물사용량 80 wt/wt, 온도 $37^{\circ}C$, 효소사용량 200unit/g tallow 조건에서 93의 가수분해율을 얻을 수 있었다.

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PET 말단에 대한 인계난연제의 라디칼계 부가반응 (2) - 리소시놀비스다이페닐포스페이트의 반응 - (Radical Addition Reaction of Phosphorous based Flame Retardant with End Groups of PET (2) - Reaction of Resorcinol bis(diphenyl phosphate) -)

  • 김민관;손광호;김한도
    • 한국염색가공학회지
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    • 제24권1호
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    • pp.39-44
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    • 2012
  • To improve flame retardation of poly(ethylene terephthalate) (PET) against burning, resorcinol bis(diphenyl phosphate) (RDP), phosphorous containing flame retardant, was incorporated into PET backbone by radical reaction pathway. Radical endcapping of PET with RDP was confirmed by spectroscopic and thermal analysis. From 400 MHz $^{31}P$ solid state FT-NMR spectrum of PET with RDP (PET-RDP), phosphorus spectra peak in RDP was found at ca. -10 ppm. Furthermore, P-C bond stretching vibration peaks were found ca. $530cm^{-1}$ in FT-IR spectrums of PET-RDP. These results indicated that RDP can be chemically bound at the ends of PET by radical addition method. Thermal characteristics of pure PET (pPET) and PET-RDP were measured and evaluated by TGA thermal analysis. There was not significant changes in thermal characteristics of PET-RDP compared to that of pPET.

Formation Mechanism of Intermediate Phase in $Ba(Mg_{1/3}Ta_{2/3})O_3$ Microwave Dielectrics

  • Fang, Yonghan;Oh, Young-Jei
    • 한국세라믹학회지
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    • 제38권10호
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    • pp.881-885
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    • 2001
  • Kinetics and mechanisms of intermediate phases formation in $Ba(Mg_{1/3}Ta_{2/3})O_3$, obtained by a solid state reaction were studied. $Ba{Ta_2}{O_6}$ and ${Ba_4}{Ta_2}{O_9}$ as intermediate products were first formed at $700^{\circ}C$. $Ba(Mg_{1/3}Ta_{2/3})O_3$ was appeared at $800^{\circ}C$. Several reactions take place on heating process. $Ba{Ta_2}{O_6}$ is found at the first stage of the reaction, and then $Ba{Ta_2}{O_6}$ or ${Ba_4}{Ta_2}{O_9}$ react with MgO to form $Ba(Mg_{1/3}Ta_{2/3})O_3$. The reaction of $Ba(Mg_{1/3}Ta_{2/3})O_3$ formation does not complete until fired at $1350^{\circ}C$ for 60 min. The kinetics of solid-state reaction between powdered reactants was controlled by diffusion mechanism, and can be explained by the Jander's model for three-dimensional diffusion.

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상대적으로 낮은 온도에서의 고상법에 의한 망간이 도핑된 Zn2SiO4 형광체 입자의 제조 및 형광특성 (Synthesis of Mn-doped Zn2SiO4 phosphor particles by solid-state method at relatively low temperature and their photoluminescence characteristics)

  • 이진화;최성옥;이동규
    • 한국산학기술학회논문지
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    • 제11권1호
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    • pp.228-233
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    • 2010
  • Methyl hydrogen polysiloxne으로 처리한 ZnO, fumed $SiO_2$와 다양한 망간 전구체를 이용하여 서브마이크로미터 크기를 갖는 망간이 도핑된 $Zn_2SiO_4$ 형광체 입자를 고상법으로 제조하였다. 결정화와 광발광 특성은 XRD, SEM, PL스펙트라를 이용하여 분석하였다. 고상법으로 제조한 망간 도핑된 $Zn_2SiO_4$는 methyl hydrogen polysiloxne 처리한 ZnO의 분산과 응집 때문에 $1000^{\circ}C$에서 성공적으로 얻어졌고, 진공자외선 여기하에서 제조된 입자의 최대 PL강도는 0.02mol Mn, $1000^{\circ}C$에서 확인되었다.

Dielectric Characteristics of PbSc1/2Nb1/2O3 Prepared by Using the One-step Solid State Reaction

  • Kim, Yeon Jung
    • Applied Science and Convergence Technology
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    • 제25권4호
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    • pp.77-80
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    • 2016
  • The $PbSc_{1/2}Nb_{1/2}O_3$ ceramics at a relatively low temperature of $1300^{\circ}C$ was successful synthesized. Solid state reaction of two-step process is not necessary. The dielectric constant, dielectric loss and admittance of ceramic samples were determined. The pyroelectric characteristics are in good agreement with the dielectric properties. Ferroelectric properties of well-formed the $PbSc_{1/2}Nb_{1/2}O_3$ ceramics are in agreement with broad distribution of relaxation phenomenon. Relatively strong frequency dependent of dielectric constant is observed at about $110^{\circ}C$. The distinct thermal hysteresis was observed in the measurement of the dielectric constant and dielectric loss. The critical exponents of during cooling and heating measurements in the $PbSc_{1/2}Nb_{1/2}O_3$ ceramics were 1.14 and 1.59 at 1 kHz, respectively.

고상합성으로 제조된 MnSi1.73:Crx의 열전특성

  • 신동길;유신욱;주경석;송권민;김일호
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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    • pp.451-451
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    • 2014
  • 중고온 열전재료로서의 응용 가능성이 높은 HMS (higher manganese silicide)는 높은 제백계수, 낮은 전기저항, 높은 산화 저항성뿐만 아니라 구성 원소가 풍부하며 친환경적인 열전재료이다. HMS는 주로 용해/응고법, 단결정 성장법에 의해 합성되지만, 구조적인 불균질성 및 많은 합성 에너지를 소비하는 단점이 있다. 또한 진성 HMS는 비교적 낮은 열전특성을 나타내기 때문에 도핑에 의한 열전특성의 개선이 필요하다. 본 연구에서는 HMS의 한 종류인 MnSi1.73에 Cr을 도핑한 화합물 MnSi1.73:Crx (x=0, 0.005, 0.01, 0.02, 0.03)를 고상반응(solid state reaction)과 진공 열간압축성형(hot pressing)을 통해 제조하였다. XRD와 Rietveld refinement를 통해 상변화 및 상분율을 분석하였고, 323~823 K까지 전기적 및 열적 특성을 측정하여 열전 성능지수(ZT)를 평가하였다.

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Eu Doping Effect on $CaAl_2O_4:Eu^{2+}$ Phosphor Material

  • Bartwal, Kunwar Singh;Ryu, Ho-Jin
    • 반도체디스플레이기술학회지
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    • 제6권2호
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    • pp.65-68
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    • 2007
  • High brightness and long persistent luminescence phosphor $CaAl_2O_4:Eu^{2+}$ was prepared with varying $Eu^{2+}$ concentration by solid state reaction technique. Synthesized materials were investigated by powder X-ray diffractometer (XRD), SEM, TEM, photoluminescence excitation and emission spectra. Broad band UV excited luminescence of the $CaAl_2O_4:Eu^{2+}$ was observed in the blue region (${\lambda}_{max}\;=\;440\;nm$) due to transitions from the $4f^65d^1$ to the $4f^7$ configuration of the $Eu^{2+}$ ion. The decay time of the persistence indicated that the persistent luminescence phosphor has bright phosphorescence and maintains a long duration. These materials have great potential for outdoor night time displays.

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형광성 Willemite의 수열, 습식 및 고상 합성에 관한 연구 (The Study on the Preparation of Fluorescence Willemite Powders by Hydrothermal, Wet and Solid State Reaction)

  • 이경희;이병하;남경호;이재영
    • 한국세라믹학회지
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    • 제28권1호
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    • pp.74-78
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    • 1991
  • Willemite powders which have been prepared by solid state reaction were easy to intermixed impurities, and particle surfaces were demaged in the progress of crushing. The above defacts were easy to accompany non-crystallization for mechanochemical effects and luminescence efficiency was deteriorated. The goal of this study improve each of defacts, and synthesize high purity and fine Mn doped willemite powders by wet and hydrothermal methods without crushing progress. It has been experimentally verified that the single phase Zn1.98Mn0.02SiO4 willemite powders which prepared by hydrothermal synthes is at 220$^{\circ}C$ for 10 hours in 2N KOH solution. The products are like needle and composition is the same with starting composition.

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정방정상과 능면체상의 경계조성 Pb(Zr, Ti)$O_3$ 세라믹스에서 화학조성의 불균일성이 상공존에 미치는 영향 (Effects of Chemical Inhomogeneity on Phase Coexistence in Pb(Zr, Ti))$O_3$ Ceramics at Morphotropic Tetragonal and Rhombohedral Phase Boundary)

  • 천채일;김호기
    • 한국세라믹학회지
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    • 제27권8호
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    • pp.1027-1033
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    • 1990
  • In order to identify the origin of phase coexistence at morphotropic tetragonal and rhombohedral boundary in PZT ceramics, the effect of chemical inhomogeneity on phase coexistence region was investigated. Two kinds of PZT ceramics with different chemical homogeneity were prepared by conventional solid state reaction and co-precipitation method. There was coexistence of tetragonal and rhombohedral phase over a wide composition range in PZT ceramics calcined by solid state reaction, and there was also phase coexistence of which region was reduced considerably in sintered samples. And phase coexistence region was not observed in co-precipitated PZT ceramics(within 1 mole%). Therefore compositional fluctuation is considered to be major origin of the phase coexistence at morphotropic phae boundary in PZT ceramics.

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Bi계 산화물 초전도체 2212상에 있어서 Bi 자리에 Ge 치환에 따른 초전도 특성 (Superconducting Properties of Ge Substitution for the Bi Site in the 2212 Phase of Bi-Sr-Ca-Cu-O Superconductors)

  • 신재수;이민수;최봉수;송승용;송기영
    • 한국세라믹학회지
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    • 제37권8호
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    • pp.787-791
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    • 2000
  • Samples with the nominal composition, Bi2-xGexSr2CaCu2O8+$\delta$ (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) were prepared by the solid-state reaction method. We have studied the effect of substitution Ge for Bi and investigated the superconducting properties by changing oxygen content with Ge substitution. It was found that temperature difference, ΔK, between TCon and TCzero was considerably smaller in the samples prepared by the intermediate pressing method than that in the samples by the solid-state reaction method. We found the solubility limit of Ge to the 80 K single phase was around x=0.3. Within the solubility limit, lattice constant c decreased with the increase of x. In the region of the 80K single phase, the onset critical temperature TCon increased and excess oxygen content decreased with increase of x.

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