• 한국결정학회지
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• 제7권2호
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• pp.126-132
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• 1996

Cholesteryl Isopropyl Carbonate(C31O3H52)의 결정구조를 X-선 회절법으로 연구하였다. 결정의 공간군은 P212121이고, 단위세포 길이는 a=6.266(4), b=10.836(5), c=47.364(20)Å, Z=4, Dc=0.98 g/cm3 이고, Dm=1.01 g/cm3이다. 회절강도들은 Nonius CAD-4 diffractometer로 얻었으며, graphite-monochromatized MoKα radiation를 사용하여 2θ로 40°까지 얻었다. 분자구조는 직접법으로 풀었으며, 정밀화는 Fourier 법과 최소자승법으로 수행하였다. 현재 R값은 0.22로 아직 풀어야 할 연구과제로 남아있다. 이 화합물의 cholesterol 부분의 구조는 다른 화합물과 비교적 잘 일치하고 있다. 결정에서 분자들이 길게 c-axis에 평행하게 놓여있고, monolayer을 이루며 쌓여있는데 cholesterol 부분은 촘촘하게 모여있는 반면 isopropyl carbonate chain들은 느슨하게 모여있어 이 결정의 liquid crystalline state성질을 나타냄을 구조로서 설명하여 준다.

• 대한화학회지
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• 제47권1호
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• pp.26-30
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• 2003

이핵 화합물, $Ag_2$[Phen]_2[S_2P(OPr)_2]_2$(Phen=1,10-phenanthroline; Pr=propyl)은 비스(디프로필디싸이오포스페이토) 은(|)화합물과 1,10 펜안트로린 리간드 반응에 의하여 합성되었고, 그 화합물 구조는 X-ray에 의하여 규명되었다. 두 디프로필디싸이오포스페이토 리간드는 두 개의 은 원자를 연결하여 팔각형 $Ag_2S_4P_2$ 고리를 형성하였고, 1,10-펜안트로린 리간드는 은 이온과 결합하여 사면체구조를 이루었다. Ag-S 결합거리는 2.471(1)와 2.567(1) ${\AA}$이었고, Ag-N 결합 거리는 2.3666(3)와 2.471(3) ${\AA}$이었다.

• 한국세라믹학회지
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• 제53권5호
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• pp.568-573
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• 2016

We explore the crystalline structure and phase transition of lithium thiophosphate ($Li_7P_3S_{11}$) solid electrolyte using electron microscopy and X-ray diffraction. The glass-like $Li_7P_3S_{11}$ powder is prepared by the high-energy mechanical milling process. According to the energy dispersive X-ray spectroscopy (EDS) and selected area diffraction (SAD) analysis, the glass powder shows chemical homogeneity without noticeable contrast variation at any specific spot in the specimen and amorphous SAD ring patterns. Upon heating up to $260^{\circ}C$ the glass $Li_7P_3S_{11}$ powder becomes crystallized, clearly representing crystal plane diffraction contrast in the high-resolution transmission electron microscopy image. We further confirm that each diffraction spot precisely corresponds to the diffraction from a particular $Li_7P_3S_{11}$ crystallographic structure, which is also in good agreement with the previous X-ray diffraction results. We expect that the microscopic analysis with EDS and SAD patterns would permit a new approach to study in the atomic scale of other lithium ion conducting sulfides.

• 디지털융복합연구
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• 제17권1호
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• pp.443-447
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• 2019

방향성탄화수소 수용체(Arylhydrocarbon Receptor, AhR)은 리간드에 의해 활성화되어 체내 외래물질의 대사를 조절하는 전사인자다. 생체 내에서 AhR의 생리학적 역할은 오랜 기간 연구되어 왔으나 활성화를 유발하지 않는 길항제를 비롯하여 유효한 화학적 도구가 아직 개발되지 않아 기능 연구가 제한적이다. AhR이 다양한 질병의 발병기전에서 중요한 역할을 수행한다는 것이 보고됨에 따라 약물 표적으로서 유효하다고 판단되나 치료나 예방을 위한 유효한 약물은 아직 개발되지 않았다. 길항제로 알려진 화합물들은 낮은 농도에서는 활성이 있어 연구 목적으로 활용되고 있으나 높은 농도에서는 방향성 탄화수소를 활성화하는 부분적 agonist로 작용한다. 이에 AhR 활성화를 유도하지 않는 순수한 길항제의 개발이 필요하다. 본 연구에서는 이미 알려진 AhR 길항제의 골격인 phenyldiazenylphenylpicolinamide의 세 고리구조 중 두 고리구조에 존재하는 메틸 기들을 변형하여 활성을 평가하는 구조-활성 관계 연구를 통하여 새로운 길항제를 개발하고자 하였다.

• Current Applied Physics
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• 제18권11호
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• pp.1458-1464
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• 2018

An improved method for the preparation of g-$C_3N_4$ is described. Currently, heating (> $400^{\circ}C$) of urea is the common method used for preparing the g-$C_3N_4$. We have found that sonication of melamine in $HNO_3$ solution, followed by washing with anhydrous ethanol, not only reduce the crystallite size of g-$C_3N_4$ but also facilitate intriguing electronic structure and photoluminescence (PL) properties. Moreover, loading of metal (Pt and Ag) nanoparticles, by applying the borohydride reduction method, has resulted in multicolor-emission from g-$C_3N_4$. With the help of PL spectra and local electronic structure study, at C K-edge, N K-edge, Pt L-edge and Ag K-edge by X-ray absorption spectroscopy (XAS), a precise mechanism of tunable luminescence is established. The PL mechanism ascribes the amendments in the transitions, via defect and/or metal states assimilation, between the ${\pi}^*$ states of tris-triazine ring of g-$C_3N_4$ and lone pair states of nitride. It is evidenced that interaction between the C/N 2p and metal 4d/5d orbitals of Ag/Pt has manifested a net detraction in the ${\delta}^*{\rightarrow}LP$ transitions and enhancement in the ${\pi}^*{\rightarrow}LP$ and ${\pi}^*{\rightarrow}{\pi}$ transitions, leading to broad PL spectra from g-$C_3N_4$ organic semiconductor compound.

• Journal of Microbiology and Biotechnology
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• 제33권6호
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• pp.707-714
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• 2023

Plant-derived insecticide-neonicotinoid insecticides (NIs) played a crucial role in the development of agriculture and food industry in recent years. Nevertheless, synthesis of these nitrogen-containing heterocyclic compounds with an effective and greener routing remains challenging especially to the notion raise of "green chemistry" and "atom economy". While bio-catalyzed methods mediated by nicotinate dehydrogenase (NDHase) then provide an alternative. The current review mainly focuses on the introduction of sources, components, structure, catalytic mechanism and applications of NDHase. Specifically, NDHase is known as nicotinic acid hydroxylase and the sources principally derived from phylum Proteobacteria. In addition, NDHase requires the participation of the electron respiratory chain system on the cell membrane. And the most important components of the electron respiratory chain are hydrogen carrier, which is mainly composed of iron-sulfur proteins (Fe-S), flavin dehydrogenase (FAD), molybdenum binding protein and cytochromes. Heterologous expression studies were hampered by the plasmid and host with high efficiency and currently only Pseudomonas entomophila L48 as well as Comamonas testosterone was successfully utilized for the expression of NDHase. Furthermore, it is speculated that the conjugate and inductive effects of the substituent group at position 3 of the substrate pyridine ring exerts a critical role in the hydroxylation reactions at position 6 concerning about the substrate molecular recognition mechanism. Finally, applications of NDHase are addressed in terms of pesticide industry and wastewater treatment. On conclusion, this critical review would not only deepen our understanding of the theory about NDHase, but also provides the guideline for future investigation of NDHase.

• Biomolecules & Therapeutics
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• 제30권2호
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• pp.191-202
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• 2022

Tetrazoles were designed and synthesized as potential inhibitors of triple monoamine neurotransmitters (dopamine, norepinephrine, serotonin) reuptake based on the functional and docking simulation of compound 6 which were performed in a previous study. The compound structure consisted of a tetrazole-linker (n)-piperidine/piperazine-spacer (m)-phenyl ring, with tetrazole attached to two phenyl rings (R1 and R2). Altering the carbon number in the linker (n) from 3 to 4 and in the spacer (m) from 0 to 1 increased the potency of serotonin reuptake inhibition. Depending on the nature of piperidine/piperazine, the substituents at R1 and R2 exerted various effects in determining their inhibitory effects on monoamine reuptake. Docking study showed that the selectivity of tetrazole for different transporters was determined based on multiple interactions with various residues on transporters, including hydrophobic residues on transmembrane domains 1, 3, 6, and 8. Co-expression of dopamine transporter, which lowers dopamine concentration in the biophase by uptaking dopamine into the cells, inhibited the dopamine-induced endoctytosis of dopamine D₂ receptor. When tested for compound 40 and 56, compound 40 which has more potent inhibitory activity on dopamine reuptake more strongly disinhibited the inhibitory activity of dopamine transporter on the endocytosis of dopamine D₂ receptor. Overall, we identified candidate inhibitors of triple monoamine neurotransmitter reuptake and provided a theoretical background for identifying such neurotransmitter modifiers for developing novel therapeutic agents of various neuropsychiatric disorders.

• 한국광물학회지
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• 제29권3호
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• pp.155-165
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• 2016

붕소가 포함된 다성분계 규산염 용융체의 원자 구조를 규명하는 것은 화산의 분화 양상을 포함한 다양한 지구화학적 과정의 원자 단위 기작을 밝히는데 중요하다. 붕소를 포함한 소듐 알루미노규산염 용융체의 붕소 및 알루미늄 주위의 원자 환경에 관한 자세한 정보는 수용액과 핵폐기물 유리(nuclear waste glasses)의 반응도(reactivity)에 대한 미시적인 설명을 제공한다. 본 연구에서는 붕소가 포함된 비정질 물질의 원자 구조 규명에 가장 적합한 고상 핵자기 공명 분광분석(solid-state nuclear magnetic resonance, solid-state NMR)을 이용하여 붕소의 함량이 비정질 소듐 보레이트($Na_2O-B_2O_3$)와 붕소를 포함한 다성분계 규산염 용융체[말린코아이트(malinkoite, $NaBSiO_4$)와 네펠린(nepheline, $NaAlSiO_4$)의 유사 이원계]의 원자 구조에 미치는 영향을 규명하였다. 비정질 소듐 보레이트의 $^{11}B$ MAS NMR 스펙트럼을 통해 붕소의 함량이 증가함에 따라 배위수가 3인 붕소($^{[3]}B$)가 증가한다는 것이 확인되었다. 비정질 말린코아이트와 네펠린의 유사 이원계의 $^{11}B$ MAS NMR 스펙트럼을 통해 $X_{Ma}$ [$=NaBSiO_4/(NaBSiO_4+NaAlSiO_4)$]가 증가함에 따라 배위수가 4인 붕소($^{[4]}B$)는 증가하는 반면 $^{[3]}B$는 감소하는 것이 관찰되었다. 다성분계 용융체의 $^{27}Al$ MAS NMR 실험 결과, 모든 조성의 용융체에서 배위수가 4인 알루미늄($^{[4]}Al$) 피크가 지배적으로 나타났다. 또한 네펠린 용융체에 붕소가 첨가되었을때 $^{[4]}Al$ 피크의 폭이 크게 감소하였고, 이는 붕소의 첨가가 네펠린 용융체 내의 알루미늄 주위의 구조적 위상학적 무질서도를 감소시킨다는 것을 지시한다. 붕소를 포함한 이원계 및 다성분계 비정질 물질의 $^{11}B$ MAS NMR 스펙트럼으로부터 시뮬레이션을 하여 붕소의 함량에 따른 붕소 원자 환경의 상대적인 존재비를 정량적으로 분석하였고, 이 결과는 붕소가 포함된 비정질 물질의 거시적 성질 변화에 대한 미시적 기작의 근원을 제시할 가능성을 보여준다.

• Journal of Photoscience
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• 제9권2호
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• pp.284-286
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• 2002

The inverted retina of the Onchidium dorsal eye (DE) is composed only of ciliary-type photoreceptor cells (CC's). The outer segment (OS) of the CC is a concentric lamellar structure consisting of many modified ciliary membranes and stains positively with anti-$\beta$-tubulin antibody. Near the base of the OS there are about 30 basal bodies each connecting individually to a cilium. The cilia are rod-shaped at the base, progressing upwards to a flattened sheet-like shape with increasing surface area. Three-dimensional analysis on serial sections demonstrates the ladle-shape of a modified cilium. Many modified cilia wrap around each other like the leaves of a cabbage. Nine pairs of microtubules (MT's) are located regularly in a ring at the base of the cilium, gradually losing their regular arrangement towards the periphery, where they separate into two subgroups that are contained within two swollen portions of a modified cilium. Within the CC of the Onchidium DE, MT's in the modified cilium exist as two poles extending longitudinally in a thin expanded ciliary membrane. This arrangement may support the photoreceptive OS and serve to maintain its structural integrity.

• 한국세라믹학회지
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• 제51권5호
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• pp.399-405
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• 2014

Porous alumina with different porosities, 5.2 - 47.5%, were coated with cover-glass having a thickness of $160{\mu}m$, using epoxy adhesive. We investigated the effect of the porosity of the substrate layer on the crack initiation load, and the size of cracks propagated in the coating layer. Hertzian indentations were used to evaluate the damage behavior under a constrained loading condition. Typically, two types of cracks, ring cracks and radial cracks, were observed on the surface of the glass/porous alumina structure. Indentation stress-strain curves, crack initiation loads, crack propagation sizes, and flexural strengths were investigated as a function of porosities. The results indicated that a porosity of less than 30% and a higher substrate elastic modulus were beneficial at suppressing cracks occurrence and propagation. We expect lightweight mechanical components with high strength can be successfully fabricated by coating and controlling porosities in the substrate layer.