• 대한수학회지
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• 제34권3호
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• pp.673-693
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• 1997

In this work, the irreducible complex representations of degree 4 of $B_4$, the braid group on 4 strings, are classified. There are 4 families of representations: A two-parameter family of representations for which the image of $P_4$, the pure braid group on 4 strings, is abelian; two families of representations which are the composition of an irreducible representation of $B_3$, the braid group on 3 strings, with a certain special homomorphism $\pi : B_4 \longrightarrow B_3$; a family of representations which are the tensor product of 2 irreducible two-dimensional representations of $B_4$.

• Molecules and Cells
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• 제42권1호
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• pp.79-86
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• 2019

Endolysins are bacteriophage-derived enzymes that hydrolyze the peptidoglycan of host bacteria. Endolysins are considered to be promising tools for the control of pathogenic bacteria. LysB4 is an endolysin produced by Bacillus cereus-infecting bacteriophage B4, and consists of an N-terminal enzymatic active domain (EAD) and a C-terminal cell wall binding domain (CBD). LysB4 was discovered for the first time as an L-alanoyl-D-glutamate endopeptidase with the ability to breakdown the peptidoglycan among B. cereus-infecting phages. To understand the activity of LysB4 at the molecular level, this study determined the X-ray crystal structure of the LysB4 EAD, using the full-length LysB4 endolysin. The LysB4 EAD has an active site that is typical of LAS-type enzymes, where $Zn^{2+}$ is tetrahedrally coordinated by three amino acid residues and one water molecule. Mutational studies identified essential residues that are involved in lytic activity. Based on the structural and biochemical information about LysB4, we suggest a ligand-docking model and a putative endopeptidase mechanism for the LysB4 EAD. These suggestions add insight into the molecular mechanism of the endolysin LysB4 in B. cereus-infecting phages.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.594-597
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• 1999

The new green and red phosphors for PDP application activated by T $b^{3+}$ and E $u^{3+}$ were synthesized, and their photoluminance properties were investigated. It was found that the brightness of $Al_3$Gd $B_4$ $O_{12}$ :T $b^{3+}$ green phosphor under 147nm VUV irradiation was higher than that of commercial Z $n_2$ $SiO_4$:M $n^{2+}$ phosphor. But the emitting intensity of A1$_3$Gd $B_4$ $O^{12}$ :E $u^{3+}$ red phosphor was inferior to the commercial (Y,Gd)B $O_3$:E $u^{3+}$. $Al_3$Gd $B_4$ $O_{12}$ Phosphor had a strong excitation band at 160nm associated with the host absorption, and also the photoluminance excitation intensity of $Al_3$Gd $B_4$ $O_{12}$ :T $b^{3+}$ was higher than that of Z $n_2$ $SiO_4$:M $n^{2+}$, but the intensity of $Al_3$Gd $B_4$ $O_{12}$ :E $u^{3+}$ phosphor was smaller than (Y,Gd)B $O_3$:E $u^{3+}$ phosphor In the VUV range. C $e^{3+}$ co-doping in A1$_3$Gd $B_4$ $O^{12}$ :E $u^{3+}$ and substitution of $Al^{3+}$ by G $a^{3+}$ A1$_3$Gd $B_4$ $O^{12}$ :E $u^{3+}$ phosphor were tried, but they did not improved the optical property .d the optical property .ty .

• Molecules and Cells
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• 제42권2호
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• pp.135-142
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• 2019

OCT4, also known as POU5F1 (POU domain class 5 transcription factor 1), is a transcription factor that acts as a master regulator of pluripotency in embryonic stem cells and is one of the reprogramming factors required for generating induced pluripotent stem cells. The human OCT4 encodes three isoforms, OCT4A, OCT4B, and OCT4B1, which are generated by alternative splicing. Currently, the functions and expression patterns of OCT4B remain largely unknown in malignancies, especially in human glioblastomas. Here, we demonstrated the function of OCT4B in human glioblastomas. Among the isoform of OCT4B, OCT4B-190 ($OCT4B^{19kDa}$) was highly expressed in human glioblastoma stem cells and glioblastoma cells and was mainly detected in the cytoplasm rather than the nucleus. Overexpression of $OCT4B^{19kDa}$ promoted colony formation of glioblastoma cells when grown in soft agar culture conditions. Clinical data analysis revealed that patients with gliomas that expressed OCT4B at high levels had a poorer prognosis than patients with gliomas that expressed OCT4B at low levels. Thus, $OCT4B^{19kDa}$ may play a crucial role in regulating cancer cell survival and adaption in a rigid environment.

• 한국분말재료학회지
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• 제22권5호
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• pp.344-349
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• 2015

$MgB_2$ bulk superconductors are synthesized by the solid state reaction of ($MgB_4$+xMg) precursors with excessive Mg compositions (x=1.0, 1.4, 2.0 and 2.4). The $MgB_4$ precursors are synthesized using (Mg+B) powders. The secondary phases ($MgB_4$ and MgO) present in the synthesized $MgB_4$ are removed by $HNO_3$ leaching. It is found that the formation reaction of $MgB_2$ is accelerated when Mg excessive compositions are used. The magnetization curves of $Mg_1+_xB_2$ samples show that the transition from the normal state to the superconducting state of the Mg excessive samples with x=0.5 and x=0.7 are sharper than that of $MgB_2$. The highest $J_c-B$ curve at 5 K and 20 K is achieved for x=0.5. Further addition of Mg decreases the $J_c$ owing to the formation of more pores in the $MgB_2$ matrix and smaller volume fraction of $MgB_2$.

• 한국분말재료학회지
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• 제9권5호
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• pp.352-358
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• 2002

The effects of boron or manganese added as $B_4C$, Mn, $TiB_2$, B on TiC-30vo1.%$Ni_3Al$ cermet sintered at 1380 and $1400^{\circ}C$ for 1 hour, were examined in relation with shrinkage, relative density, microstructure, lattice parameter, hardness and fracture toughness ($K_{IC}$). The results are summarized as follows: 1) The highest shrink-age showed about 30.5% in the specimen added B$_4$C and the maximum relative density was about 99% in the specimen added $TiB_2$; 2) The grains of TiC were grown during sintering and made the surrounding structure by adding boron and manganese. The largest grain size showed about $2.8\mutextrm{m}$ in the specimen with boron sintered at $1400^{\circ}C$;3) The lattice parameter of TiC was about $4.325\AA$ and $Ni_3Al$ about $3.592\AA$ by adding other elements; 4) The highest hardness was about $1100kgf/\textrm{mm}^2$ in the specimen with B4C; 5) The fracture toughness ($K_{IC}$) showed about $15MNm^{-3/2}$ in the specimen added $TiB_2$.

• 한국동물학회지
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• 제32권4호
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• pp.420-428
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• 1989

Pseudogobio esocinus의 심장, 신장 및 간 조직은 하부단위체 C를 함유하는 젖산수소이탈효소를 갖고 있음이 확인되었다. 하부단위체 A 및 B에 대한 유전자들의 조직 발현은 다른 포유동물의 것과 유사하였으며 분자량은 140,000 정도로 추정되었다. Oxamate gel을 사용한 chromatography결과 A4 동위효소는 NAD+보다는 column buffer에 의해 용출되었다. B4 동위효소는 CM-Sepharose column을 사용하여 부붙 정제되었다. B4 동위효소는 물론 A4 동위효소도 고농도의 Pyruvate에 의해 저해되었다. A4 동위효소의 affinity chromatography 상 행동과 Pyruvate 저해 정도로 보아 A4 등위효소는 B4 동위효소 두 역학적으로 유사하다고 사료된다. P. esainus A4 동위효소에 대한 항체는 mouse A4 등위효소와 반응하지만 동종의 B4 동위 효소와는 반응하지 않는 특성으로 보아 하부단위체 B는 진화과정에서 보존성이 낮은 것으로 사료된다. Three tissues of heart, kidney and liver of a primitive cvprinid Pseudogobio esocinus were found to have lactate dehydrogenase isozyme(5) containing subunit C. Tissue expressions of genes for subunits A and B were similar to those of mammalian species. Molecular weight of the isozymes were estimated to be 140,000 approximately. Affinity chromatography of the isozymes on the immobilized oxamate gel revealed that A4 isozyme was not elected in NAD+ but in column buffer. B4 isozune was isozpnatically purified by subjecting kidney extract to a CM-Sepharose column. Ae isozvme as well as B4 isozvme was inhibited by high concentrations of pyruvate. The affinity chromatographic behavior and susceptibility to pyruvate inhibition of the A4 isorpne suggest that A4 isozwne is similar to B4 isozyme kinetically. Antibodies against p. esocinus A4 isogyme reacted with mouse At isozyme but not with p. esocinus B4 isogyme, reflecting that subunit B is less conservative in its evolution.

• 한국재료학회지
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• 제8권11호
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• pp.1026-1030
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• 1998

Fe기 비정질합금에서 과냉각액체영역의 유무에 따른 열적 안정성을 비교평가하기 위하여 결정화온도 이하에서 유리천이가 나타나지 않는 $Fe_{80}P_6C_{12}B_{12}$합금과 52K의 과냉각 액체영역을 갖는 $Fe_{73}P_{11}C_6B_4AI_4Ge_2$ glassy 합금을 열분석하였다. 등온결정화에 의한 열분석의 결과 JMA plot의 n값은 $Fe_{80}P_6C_{12}B_{12}$합금이 1.8-2.2이고 과냉각 액체영역을 갖는 $Fe_{73}P_{11}C_6B_4AI_4Ge_2$ 합금이 2.5-4.0으로서 후자의 경우가 열적으로 안정하였다. 결정화의 양상은 $Fe_{80}P_6C_{12}B_{12}$ 합금의 경우 핵생성속도가 일정할 때 확산율속에 의해 결정입자가 성장하는 반면 $Fe_{73}P_{11}C_6B_4AI_4Ge_2$ glassy합금의 경우 핵생성속도가 일정할 때 계면입자가 성장한다. $Fe_{73}P_{11}C_6B_4AI_4Ge_2$ 합금 및 $Fe_{80}P_6C_{12}B_{12}$ 합금의 결정화에 필요한 활성화에너지, 핵생성 및 성장에 필요한 활성화에너지는 각각 371, 353kJ/mol, 그리고 324, 301KJ/mol 및 301, 273KJ/mol로서 과냉각 액체영역을 갖는 합금이 열적으로 안정하다고 판단된다.

• Bulletin of the Korean Chemical Society
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• 제31권4호
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• pp.984-988
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• 2010

1-(Fluoren-2-yl)-benzo[d][1,2,3]triazoles 5a-b were synthesized starting from 2-nitrofluorene. 2-Nitrofluorenes 1a-b were reduced by catalytic hydrogenation, reacted with 2,4-dinitrofluorobenzene followed by catalytic hydrogenation to afford 2-(N-2,4-diaminophenyl)aminofluorenes 4a-b. Diazotization of 4a-b with $NaNO_2/H_2SO_4$ followed by treatment with $H_3PO_2$ gave 5a-b. Sulfonation of 5a-b yielded 7-benzotriazol-1-yl-fluorene-2-sulfonic acids 6a-b. The structures of 5b and 6b were firmly identified by X-ray crystal analysis in addition to $^1H$ NMR, $^{13}C$ NMR, and elemental analysis.

• Korean Chemical Engineering Research
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• 제54권5호
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• pp.587-592
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• 2016

휴대용 고분자전해질 연료전지의 수소발생용으로써 $NaBH_4$는 많은 장점을 갖고 있다. 본 연구에서는 고농도 $NaBH_4$ 용액에서 비담지 Co-P-B, Co-B 촉매의 $NaBH_4$ 가수분해 특성에 대해 연구하였다. 고농도에서 수소 발생 수율을 높이기 위해 $NaBH_4$ 가수분해 반응의 수소 발생 수율에 미치는 촉매 형태, $NaBH_4$ 농도, 응축수 회수 등의 영향에 대해 실험하였다. Co-P-B 제조과정에서 붕소의 비가 높아질수록 수소 발생 수율이 증가하였다. Co-P:B = 1:5 촉매를 사용해 $NaBH_4$ 수용액 농도를 20 wt%에서 25 wt%로 증가시켰을 때 수소 발생 수율이 감소하였다. Co-P-B와 Co-B 촉매를 같이 사용한 반응기에서 촉매 팩의 두께를 감소시키고 응축수를 회수하여, $NaBH_4$ 25 wt% 수용액으로 최고 수소 발생수율 96.4%를 얻었다.