• 분석과학
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• 제36권2호
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• pp.70-79
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• 2023

The synthesis of the Mannich base as a ligand (L) N-(morpholino (phenyl) methyl) acetamide is the subject of this study. Elemental analyses, FT-IR spectra, UV-vis, ¹H-NMR, and magnetic measurements were used to confirm the synthesis of the [Ni(L)₂]Cl₂ complex, thermal analysis (TG/DTG), atomic absorption, and scanning, and structurally explained as electron microscopy (SEM), and X-ray powder diffraction (XRD) methods. The melting point of the complex and its molar conductivity were also measured. The suggested geometries of the complexes formed have a tetrahedral structure, according to the data acquired using various techniques. Theoretical approaches to the complex formation have been investigated. For molecular mechanics and semi-empirical calculations, the HYPERCHEM6 program had been used. The effect of the novel Ni(II) complex on the cancer cell Hepa-2 (human hepatocellular ademocarcinoma), that is the human laryngeal cancer, was studied. It has been found that these ligand and complex have potent effects on the cancer cell. The antibacterial activity of the free ligand and its complex was evaluated against two kinds of human pathogenic bacteria. The first category is Gram-positive (Staphylococcus aureas, epiderimids), whereas the second group is Gram-negative (Psedamonas aeruginosa, Escherichia coli) (from the diffusion method). Finally, it was discovered that various chemicals had varied growth-inhibiting effects on bacteria.

• Advances in nano research
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• 제16권1호
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• pp.91-109
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• 2024

Carbon nanotubes are drawing wide attention of research communities and several industries due to their versatile capabilities covering mechanical and other multi-physical properties. However, owing to extreme operating conditions of the synthesis process of these nanostructures, they are often imposed with certain inevitable structural deformities such as single vacancy and nanopore defects. These random irregularities limit the intended functionalities of carbon nanotubes severely. In this article, we investigate the mechanical behaviour of double-wall carbon nanotubes (DWCNT) under the influence of arbitrarily distributed single vacancy and nanopore defects in the outer wall, inner wall, and both the walls. Large-scale molecular simulations reveal that the nanopore defects have more detrimental effects on the mechanical behaviour of DWCNTs, while the defects in the inner wall of DWCNTs make the nanostructures more vulnerable to withstand high longitudinal deformation. From a different perspective, to exploit the mechanics of damage for achieving defect-induced shape modulation and region-wise deformation control, we have further explored the localized longitudinal and transverse spatial effects of DWCNT by designing the defects for their regional distribution. The comprehensive numerical results of the present study would lead to the characterization of the critical mechanical properties of DWCNTs under the presence of inevitable intrinsic defects along with the aspect of defect-induced spatial modulation of shapes for prospective applications in a range of nanoelectromechanical systems and devices.

• Elastomers and Composites
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• 제37권3호
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• pp.170-176
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• 2002

공정조제의 성분 및 함량이 styrene-butadiene rubber (SBR) 배합고무의 유변학적 특성과 기계적 물성에 미치는 영향을 조사하였다. 공정조제로 지방산, 지방산 유도 금속염, 에스테르 알코올, 아미드 성분을 단독 혹은 혼합한 5종의 상용제품을 선택하였다. 공정조제 첨가에 따른 무니점도와 전단점도의 감소는 금속염이 주성분인 공정조제가 가장 컸고, 고분자량의 지방산 알콜이나 에스터의 함량이 높은 공정조제가 낮았다. 공정조제의 함량증가에 따라 인장 모듈러스는 감소하고, 발열은 증가하는 경향을 나타내었지만, 극한물성인 인장강도와 파단신장율에는 그다지 큰 영향을 미치지 않았다.

• Korea-Australia Rheology Journal
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• 제20권3호
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• pp.109-116
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• 2008

The effect of intermolecular aggregation induced by hydrophobic and electrostatic interactions on shear and elongational flow properties of aqueous acrylic thickener solutions is discussed. Complex shear modulus is determined at frequencies up to $10^4$ rad/s employing oscillatory squeeze flow. Extensional flow behavior is characterized using Capillary Break-up Extensional Rheometry. Aqueous solutions of poly(acrylic acid)(PAA)/poly(vinylpyrrolidone-co-vinylimidazole) (PVP-VI) mixtures exhibit unusual rheological properties described here for the first time. Zero-shear viscosity of the mixtures increases with decreasing pH and can exceed that of the pure polymers in solution by more than two orders of magnitude. This is attributed to the formation of complexes induced by electrostatic interactions in the pH range, where both polymers are oppositely charged. PAA/PVP-VI mixtures are compared to the commercial thickener Sterocoll FD (BASF SE), which is a statistical co-polymer including (meth) acrylic acid and ethylacrylate (EA) forming aggregates in solution due to "sticky" contacts among hydrophobic EA-sequences. PAA/PVP-VI complexes are less compact and more deformable than the hydrophobic Sterocoll FD aggregates. Solutions of PAA/PVP-VI exhibit a higher zero-shear viscosity even at lower molecular weight of the aggregates, but are strongly shear-thinning in contrast to the weakly shear-thinning solutions of Sterocoll FD. The higher ratio of characteristic relaxation times in shear and elongation determined for PAA/PVP-VI compared to Sterocoll FD solutions reflects, that the charge-induced complexes provide a much stronger resistance to extensional flow than the aggregates formed by hydrophobic interactions. This is most likely due to a break-up of the latter in extensional flow, while there is no evidence for a break-up of complexes for PAA/PVP-VI mixtures. These flexible aggregates are more suitable for the stabilization of thin filaments in extensional flows.

• Structural Engineering and Mechanics
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• 제89권5호
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• pp.525-538
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• 2024

An explosion from a specific source can generate high pressure, causing damage to structures and people in and around them. For the design of protective structures, although explosion overpressure is considered the main loading parameter, parts are only considered using standard design procedures, excluding special installations. Properties of the explosive, such as molecular structure, shape, dimensional properties, and the physical state of the charge, determine the results in a high-grade or low-grade explosion. In this context, it is very important to determine the explosion behaviors of the structures and to take precautions against these behaviors. Especially structures in areas with high explosion risk should be prepared for blast loads. In this study, the behavior of non-anchored blast resistant modular buildings was investigated. In the study, analyzes were carried out for cases where modular buildings were first positioned on a reinforced concrete surface and then directly on the ground. For these two cases, the behavior of the modular structure placed on the reinforced concrete floor against burst loads was evaluated with Stribeck curves. The behavior of the modular building placed directly on the ground is examined with the Pais and Kausel equations, which consider the structure-ground interaction. In the study, head and neck injuries were examined by placing test dummies to examine human injury behavior in modular buildings exposed to blast loads. Obtained results were compared with field tests. In both cases, results close to field tests were obtained. Thus, it was concluded that Stribeck curves and Pais Kausel equations can reflect the behavior of modular buildings subjected to blast loads. It was also seen at the end of the study that the human injury criteria were met. The results of the study are explained with their justifications.

• Composites Research
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• 제30권5호
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• pp.323-330
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• 2017

본 연구에서는 폴리프로필렌 내에 투입된 탄화규소 나노 입자들의 군집현상이 나노복합재의 역학적 거동에 미치는 영향을 고찰하기 위해 분자동역학 전산모사를 통해 얻은 정보를 연속체 역학 수준에 적용시키는 멀티스케일 해석을 수행하였다. 입자 간의 거리에 따른 계면 물성의 하락을 반영하는 모델을 이용하여, 다양한 군집 상황에 따른 고분자 나노복합재의 탄성거동 변화를 관찰하였다. 또한, 나노복합재의 기계적 거동에 영향을 미치는 주요 요인을 파악하여 군집밀도라는 새로운 지표를 정의하였다. 나노 입자의 군집밀도와 나노복합재의 탄성거동 간의 상관관계를 파악한 결과, 군집밀도의 값이 증가할수록 계면효과가 저하되어 최종적으로 나노복합재의 기계적 물성 상승이 억제되었다. 나노 입자의 랜덤분포를 고려한 해석을 통해, 동일한 군집밀도의 수치에 대해 나노복합재가 가질 수 있는 탄성계수의 범위를 파악할 수 있었다. 상관관계는 지수 함수형태로 표현될 수 있었으며, 이를 통해 나노 입자의 군집밀도를 이용하여 고분자 나노복합재의 기계적 거동을 효과적으로 예측 가능하다.

• 대한화학회지
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• 제39권12호
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• pp.940-945
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• 1995

입체특이성을 가지는 N, N'-bis-[2(S)-pyrrolidinylmethyl]ethane-1, 2-diamine(SS-epm) 리간드를 합성하여, $CoCl_2{\cdot}6H_2O$와 trans-$[Co(pyridine)_4Cl_2]Cl$에 각각 반응시켜 녹색결정을 얻었다. 원소분석과 전자흡수스펙트럼 자료에 따라 trans-$[Co(SS-epm)Cl_2]_2(COCl_4)$의 조성을 갖게됨을 확인하였다. 또한, 착물의 CD스펙트럼에서는 리간드의 입체특이성으로 인해 vicinal effect가 유발되었고, 장파장에서 음(-)의 cotton 효과를 나타내었으며, 킬레이트된 리간드의 conformation은 5원 킬레이트고리에 대해 ${\delta}{\lambda}{\delta}$(SRRS)를 취하고 있었다. SS-epm 리간드가 배위된 trans형 착물의 생성은 대이온으로 작용한 $Co(II)Cl_4^{2-}$가 대단히 중요한 이온회합 효과를 갖고 있음을 알게 되었다. 아울러, 분자역학(MM)적 방법으로 이차아민의 배향에 따른 각 이성질체의 strain energy를 계산하여, 평형상태에서 안전한 이성질체를 찾고, 동시에 분광학적 자료와 비교 검토하였다.