• Carbon letters
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• 제14권1호
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• pp.14-21
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• 2013

Physically and chemically activated carbons (ACs) exhibited high adsorption capacities for organic and inorganic pollutants compared with other adsorbents due to their expanded surface areas and wide pore volume distribution. In this work, seven steam-ACs with different burn-off have been prepared from cotton stalks. The textural properties of these sorbents were determined using nitrogen adsorption at $-196^{\circ}C$. The chemistry of the surface of the present sorbents was characterized by determining the surface functional C-O groups using Fourier transform infrared spectroscopy, surface pH, $pH_{pzc}$, and Boehm's acid-base neutralization method. The textural properties and the morphology of the sorbent surface depend on the percentage of burn-off. The surface acidity and surface basicity are related to the burn-off percentage. A theoretical model was developed to find a mathematical expression that relates the % burn-off to ash content, surface area, and mean pore radius. Also, the chemistry of the carbon surface is related to the % burn-off. A mathematical expression was proposed where % burn-off was taken as an independent factor and the other variable as a dependent factor. This expression allows the choice of the value of % burn-off with required steam-AC properties.

• 동굴
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• 제71호
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• pp.1-4
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• 2006

Chloromethylnaphthalene is a valuable compound for obtaining of the plant growing stimulator - -napthylacetic acid. Chloromethylation of naphthalene by paraformaldehyde in the presence of glacial acetic acid, phosphoric and hydrochloric acids at temperature 80 - 85C and duration - 6 hours the -chloromethylnaphthalene yield was 55-57%. Using Box-Wilson method for mathematical planning of experiment carried out optimization of its synthesis for purpose increasing -chloromethylnaphthalene yield. Preliminary, one - factor experiments were carried out for selecting independence main parameters influencing on the synthesis. A full factor experiment of 23 with extended matrix of planning was used for optimization. Aiming to increase the -chloromethylnaphthalene yield, the obtained mathematical model was used for program of sharp raising on the reply surface. The received optimal conditions for the -chloromethylnaphthalene synthesis were selected as following: molar ratio of naphthalene parapfsormaldehyde of 1 : 2 temperature - 105C duration of the reaction - 3 hours. The yield of -chloromethylnaphthalene under these optimal conditions was 75%.

• Bulletin of the Korean Chemical Society
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• 제4권1호
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• pp.28-36
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• 1983

We considered the tunneling effect on the rate constants calculated from transition-state theory for the H + $D_2$ and D + $H_2$ reactions. A method for evaluating the important parameter Ec (potential barrier height) was proposed. A tunnel-effect correlation factor (TECF) ${\Gamma}_{t}exp{\theta}_t$ was estimated from experimental data, and compared with the corresponding values obtained from many theoretical methods. According to our results, the tunneling effect cannot be negligible around $800^{\circ}$K where the TECF value is ca. 0.8 whereas the factor approaches to unity at T > $2400^{\circ}$K where the tunneling completely disappears. In addition to the above fact, we also found that the TECF for the D + $H_2$ reaction is greater than that of the H + $D_2$ reaction in agreement with Garrett and Truhlar's result. In contrast to our result, however, Shavitt found that the order is reversed, i.e., TECF for (D + $H_2$) is greater than that for (H + $D_2$). We discussed about the Shavitt's result.

• Biomolecules & Therapeutics
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• 제32권4호
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• pp.492-498
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• 2024

Bioassay and HPLC-UV guided fractionations of the crude extract of marine-derived Streptomyces sp. SNA-077 have led to the isolation of a red pigment, undecylprodigiosin (1). The chemical structure of undecylprodigiosin (1) was revealed by the interpretation of NMR and mass spectroscopic (MS) data. Further, anti-melanogenic effects of undecylprodigiosin (1) were investigated. First, the melanin contents of undecylprodigiosin (1)-treated B16 cells were evaluated. Furthermore, undecylprodigiosin (1) significantly inhibited the key enzymes involved in melanogenesis, including tyrosinase, tyrosinase related protein-1 (TYRP-1), and dopachrome tautomerase (DCT). The mRNA and protein expression levels of Microphthalmia-associated transcriptian factor (MiTF), a critical transcription factor for tyrosinase gene expression, were also suppressed by undecylprodigiosin (1) treatment in B16 analyses. Collectively, our results suggest for the first time that undecylprodigiosin (1), a potent component isolated from an extract of marine Streptomyces sp. SNA-077, critically exerts the anti-melanogenic ability for melanin synthesis.

• 생명과학회지
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• 제19권5호
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• pp.561-565
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• 2009

인간조직인자는 혈액응고인자 factor VII 과 복합체를 형성하며 연속적인 혈액응고 연쇄반응을 촉매하는 효소 활성체이다. 복합체 형성에 필수적인 이 조직인자의 세포 외 부분이, 기존의 융합 단백질 및 히스티딘 말단이 없는 새로운 발현 벡터에 의해 대장균 내에서 과량 발현 되었다. 봉입체 형태로 발현된 재조합 인간조직인자는 DEAE-Sephacel 크로마토그라피 기술을 적용하여 분리, 정제 및 구조적 복원이 동시에 시도 되었다. 정제된 재조합 단백질은 SDS-PAGE 분석에서 순수한 형태로 나타났으며, 생물학적 활성도 또한 기존의 조직인자와 거의 동등함을 보였다. 본 연구의 발현 및 정제 시스템은 이전의 보고에서 보여진 방법들에 비해 단백질 분해효소를 사용하지 않아 추가적인 크로마토그라피 과정이 필요 없어 좀 더 효율적이기 때문에 기존의 발현 시스템에 대해 대체할 수 있는 매우 유용한 방법으로 제공된다.

• Molecules and Cells
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• 제25권1호
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• pp.70-77
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• 2008

Proteome analysis was performed to identify proteins differentially expressed in an Arabidopsis mutant, ntm1-D. In this mutant the NAC transcription factor NTM1 is constitutively expressed and the resultant phenotypic changes include dwarfism, serrated leaves, and altered floral structures, probably due to reduced cell division. Marked elevation of proteins mediating environmental stress responses, including annexin, vegetative storage proteins, beta-glucosidase homolog 1, and glutathione transferases was observed. Overexpression of annexin was confirmed by RT-PCR and Western blotting. These observations suggest that the reduced growth observed in the ntm1-D mutant is caused by enhancement of its stress responses, possibly resulting in a cost in fitness.

• 대한화장품학회지
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• 제46권1호
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• pp.11-22
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• 2020

본 연구에서는 6 개의 아미노산으로 이루어진 헥사펩타이드(hexapeptide)의 미백 효능에 대해 수행하였다. 실험 결과 헥사펩타이드 처리에 의해 유의한 수준의 멜라닌 생성 저해가 관찰 되었고, 멜라닌 생성 과정에 관여하는 주요 효소인 tyrosinase의 활성이 농도 의존적으로 억제됨이 관찰 되었다. 멜라닌 생성 관련 인자들의 발현을 관찰 한 결과 tyrosinase (TYR), tyrosinase-related protein 1 (TYRP1) 및 이들의 상위 전사인자인 microphthalmia-associated transcription factor (MITF)의 발현이 헥사펩타이드 처리에 의해 유의한 수준으로 저해 되었다. 또한 헥사펩타이드 처리에 의해 MITF 발현을 조절하는 상위 전사인자인 cAMP-response element binding protein (CREB)의 인산화가 저해 되었고 MITF 인산화를 통해 프로테아좀 분해(proteasomal degradation)를 유도하는 extracellular signal-regulated kinase (ERK) 인산화가 증가 되었다. 이외에도, 멜라노좀의 세포 내 이동에 관여하는 복합체의 구성 인자들로 알려진 Rab27A, melanophilin, myosinVa의 발현도 헥사펩타이드에 의해 유의한 수준으로 저해 되었다. 이 결과를 통해, 본 연구의 헥사펩타이드는 멜라닌세포의 멜라닌 생성 관련 핵심 전사인자인 MITF의 발현 및 분해 조절을 통해 멜라닌 생성 억제 및 멜라노좀 이동과 같은 전반적인 멜라노좀 성숙 과정에 저해 효과를 나타내는 것으로 보인다. 헥사펩타이드의 이러한 미백 효능은 신규 미백 기능성 화장품 소재로 응용될 수 있을 것으로 기대된다.

• 대한방사선협회지
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• 제25권1호
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• pp.317-323
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• 1999

The response of endothelial cells to ionizing radiation is thought to be an important factor in the overall response of normal tissue. It has been reported that basic fibroblast growth factor (bFGF), a potent mitogen for endothelial cells, protects endoth

• Bulletin of the Korean Chemical Society
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• 제29권2호
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• pp.450-462
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• 2008

The physical chemistry (PC) articles published in the Bulletin of the Korean Chemical Society (BKCS) from 2003 to 2007 are surveyed, and in-depth content analysis was conducted to classify the PC articles into 12 topics used in The Journal of Physical Chemistry (JPC). The PC articles published in the Journal of the American Chemical Society (JACS) in 2007 are also surveyed. The extensive summary of all PC articles in BKCS for the last five years reveals the current trend of physical chemistry research in Korea. The comparison study with the JACS shows that the proportion of PC articles among all articles published in BKCS (16%) is slightly higher than that of JACS (11%), and the non-Korean authorship ratio of BKCS (12%) is very low compared with the non-US authorship of JACS (52%). From the comparison study with articles published in JPC in 2007, it is found that BKCS disseminates various topics of physical chemistry researches adequately. In particular, BKCS most frequently published PC articles in molecular structure and spectroscopy topics, whereas JPC published surface chemistry and nano-chemistry articles most frequently. It is concluded that BKCS should publish more articles to be a leading journal, and it is suggested that the SCI impact factor of BKCS must be increased by improving the electronic version of BKCS.

• Bulletin of the Korean Chemical Society
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• 제31권7호
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• pp.2039-2042
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• 2010