• Title/Summary/Keyword: Calorimetry

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Effective Absorption Capacity of Highly Absorptive Materials using Isothermal Calorimetry, Considering the Effect of Specific Surface Area (등온열량계를 사용한 고흡수성 재료의 유효흡수율 측정: 비표면적의 영향)

  • Lee, Bo Yeon
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.34 no.2
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    • pp.49-56
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    • 2018
  • The use of highly absorptive materials in cement-based materials is increasing for internal curing purpose. However, calculation of correct absorption capacity of such materials is not easy, which leads to change in the effective water-to-cement ratio of cement paste by either absorbing or releasing water. In this study, effective absorption capacity of a highly absorptive material was found using isothermal calorimetry. Moreover, the effect of specific surface area was investigated. It was found that the method was capable of finding effective water absorption capacity of activated carbon fiber. For the activated carbon fiber used in this research, the effect of specific surface area was negligible because the high BET surface area was due to micropores less than 1nm, which does not affect the rate of hydration curve. Thus, the effective absorption capacity of such materials can be found successfully using this method.

Engineering and Characterization of the Isolated C-Terminal Domain of 5-Enolpyruvylshikimate-3-phosphate (EPSP) Synthase

  • Kim, Hak-Jun;Kim, Hyun-Woo;Kang, Sung-Ho
    • Journal of Microbiology and Biotechnology
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    • v.17 no.8
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    • pp.1385-1389
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    • 2007
  • 5-Enolpyruvylshikimate-3-phosphate (EPSP) synthase catalyzes the formation of EPSP and inorganic phosphate from shikimate-3-phosphate (S3P) and phosphoenolpyruvate (PEP) in the biosynthesis of aromatic amino acids. To delineate the domain-specific function, we successfully isolated the discontinuous C-terminal domain (residues 1-21, linkers, 240-427) of EPSP synthase (427 residues) by site-directed mutagenesis. The engineered C-terminal domains containing no linker (CTD), or with gly-gly ($CTD^{GG}$) and gly-ser-ser-gly ($CTD^{GSSG}$) linkers were purified and characterized as having distinct native-like secondary and tertiary structures. However, isothermal titration calorimetry (ITC), $^{15}N-HSQC$,\;and\;^{31}P-NMR$ revealed that neither its substrate nor inhibitor binds the isolated domain. The isolated domain maintained structural integrity, but did not function as the half of the full-length protein.

A Scanning Calorimetric Study of the Effect of Clover Saponin on Liposomal Phospholipid Membrane

  • Bae, Song-Ja;Han, Suk-Kyu;Im, Kwang-Sik;Kim, Nam-Hong
    • Archives of Pharmacal Research
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    • v.11 no.3
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    • pp.181-184
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    • 1988
  • The effect of clover saponin on the phase transition of liposomal lipid bilayers of dimyristoyl phosphatidylcholine was investigated with differential scanning calorimetry. The thermograms of the liposomal bilayers incorporated with the clover saponin were obtained, and the enthalpy changes and the sizes of cooperative unit of the transition were calculated. The results showed that incorporation of the clover saponin into the liposomal bilayers effectively reduced the transition temperature at which the transition from solid state to liquid-crystalline state occurs, and broadened the thermogram peaks. It also reduced the size of cooperative unit of the transition. These results indicate that the clover saponin might have significant effect on the fluidity of biological membranes.

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Bromination of Alkyl Chlorides by LiBr and CaBr2 adsorbed on Alumina (LiBr와 CaBr2가 흡착된 알루미나상에서 일어나는 염화 알킬의 브롬화반응)

  • Park, Yeong Hoon;Shin, Young Mun;Cho, Beom Jun;Kim, Chang Bae
    • Applied Chemistry for Engineering
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    • v.7 no.5
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    • pp.1015-1019
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    • 1996
  • Several alkyl chlorides were brominated using LiBr and $CaBr_2$ adsorbed on alumina in the absence of solvent. The yields of alkyl bromides were fairly high. Such a high reactivity by these bromide salts might be due to the interaction of minute amount of water and the salt on alumina. Differential scanning calorimetry (DSC) thermogram was provided and discussed.

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Interaction of FERM Domain of Tumor Suppressor, Merlin to its C-terminal Domain. (종양 억제 인자, Merlin의 FERM 도메인과 C-말단 도메인간의 결합)

  • Oh, Jeong-Il;Kang, Beom-Sik
    • Journal of Life Science
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    • v.17 no.9 s.89
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    • pp.1303-1307
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    • 2007
  • A tumor suppressor, merlin is a member of ERM family proteins. It consists of N-terminal FERM domain, ${\alpha}-helical$ region, and C-terminal domain. Alternative splicing of merlin's mRNA generates two isotypes of merlin. Isotype I, which has exon17 at the C-terminus instead of exon16 in isotype II, is known to have tumor suppressor activity. Like other ERM proteins, the C-terminal domain of merlin isotype I interacts to its FERM domain. That of isotype II, however, was reported not to bind FERM domain despite the large common part of C-terminal domain, which possibly binds FERM domain. Here, we show the binding of FERM domain to both C-terminal domains of merlin's two isotypes by isothermal titration calorimetry. These results support that merlin isotype II also can form a closed conformation or a multimer by intramolecular or intermolecular interactions using their FERM domain and C-terminal domain.

Oxidation Stability of PAO Oils Determined by Differential Scanning Calorimetry

  • Shim, Joosup;Cho, Wonoh;Chung, Keunwo
    • Tribology and Lubricants
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    • v.12 no.1
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    • pp.36-41
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    • 1996
  • The suitability of a pressure differential scanning calorimetry (PDSC) in monitoring the quality of synthetic base fluids has been investigated using polyalphaolefin (PAO) oils as an example. Induction period meassured at 170, 180 and 19$0^{\circ}C$, and 3.53 MPa oxygen pressure was applied to characterize their oxidation stability. The PDSC method has proven to be simple and repeatable and requires only small sample size for testing. More importantly, it can be applied in differentiating the oxidation performance quality of PAO oils and is versatile enough for use in studying kinetic aspects of PAO oil oxidation which include the effect of temperature and antioxidant concentration. Additionally, the method appears to correlate well with a rotary bomb oxidation test (RBOT).

Compatibility Study Using Differential Scanning Calorimetry (시차주사열량분석을 이용한 배합성 연구)

  • Sohn, Young-Taek;Lee, Aea-Kyoung
    • Journal of Pharmaceutical Investigation
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    • v.29 no.2
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    • pp.117-126
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    • 1999
  • Differential scanning calorimetry(DSC) was used as a screening technique for assessing the compatibility of some drugs with excipients. On the basis of DSC results, interaction of ibuprofen with PVP K40 was found and eutectic formations with PEG 6000 or magnesium stearate were demonstrated. Fenoprofen Ca was found to interact with PEG 6000. Naproxen showed interactions with PEG 6000, PVP K40, PVPP and Mg stearate. Interactions of tiaprofenic acid with PVP K40 or PVPP were found and eutectic formations with PEG 6000 or Mg stearate were observed. Bisoprolol hemifumarate, metoprolol tartrate and penbutolol sulfate were found to interact with lactose.

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Study on the Polymorphism of Sulfa Drugs (설파제의 다형(多形)에 관한 연구)

  • Sohn, Young-Taek
    • Journal of Pharmaceutical Investigation
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    • v.20 no.1
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    • pp.35-42
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    • 1990
  • A new form of sulfabenzamide was characterized using X-ray diffraction patterns and differential scanning calorimetry. Solubility studies demonstrated that, of the sulfabenzamide polymorphs, the new form was more soluble than form I. Compression of the new form at compression force of 1000 $kg/cm{^2}$ didn't induce polymorphic change in the crystal. Similar patterns were also produced through grinding. The effects of some diluents on the polymorphic transformation from the new form into form I by grinding and compression were also studied. Three diluents, $Avicel^{\circledR}$, lactose and starch showed no influence on the polymorphic transformation. The new form seemed to be more suitable for the pharmaceutical preparation.

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Synthesis and Characterisation of Hole Transporting Materials Based on N,N,N-Tris-[4-(Naphthalen-1-yl-phenylamino)Phenyl]-N,N,N-Triphenylbenzene-1,3,5-Triamine (N,N,N-Tris-[4-(Naphthalen-1-yl-phenylamino)Phenyl]-N,N,N-Triphenylbenzene-1,3,5-Triamine을 이용한 Hole Transporting 재료의 합성)

  • Mathew, Siji;Haridas, Karickal R.
    • Journal of the Korean Chemical Society
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    • v.54 no.6
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    • pp.717-722
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    • 2010
  • Two derivatives of star shaped compounds based on naphthylamine with symmetric trisubstituted benzene as core, methoxy and ethoxy as end substitutions are synthesized. The synthesized compounds are characterized by UV-visible, FT-IR and NMR spectrometric techniques. The electronic and thermal properties of the compounds are studied using cyclic voltametry (CV) and differential scanning calorimetry (DSC) respectively. The data's obtained have similarity with the arylamines that have been already used in optoelectronic devices. So these compounds are interesting materials for applications in such devices.