• Advances in nano research
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• 제16권1호
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• pp.53-69
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• 2024

Advancements in the technology of building materials has led to diverse applications of nanomaterials with the aim to monitor concrete structures. While there are myriad instances of the use of nanoparticles in building materials, the production of smart nano cement-composites is often expensive. Thereupon, this research aims to discover a sustainable nanomaterial from tyre waste using the pyrolysis process as part of the green manufacturing circle. Here, Nano Structure Tyre-Char (NSTC) is introduced as a zero-dimension carbon-based nanoparticle. The NSTC particles were characterized using various standard characterization techniques. Several salient results for the NSTC particles were obtained using microscopic and spectroscopic techniques. The size of the particles as well as that of the agglomerates were reduced significantly using the milling process and the results were validated through a scanning electron microscope. The crystallite size and crystallinity were found to be ~35nm and 10.42%, respectively. The direct bandgap value of 5.93eV and good optical conductivity at 786 nm were obtained from the ultra violet visible spectroscopy measurements. The thermal analysis reveals the presence of a substantial amount of carbon, the rate of maximum weight loss, and the two stages of phase transformation. The FT-Raman confirms the presence of carboxyl groups and a ID/IG ratio of 0.83. Water contact angle around 140° on the surface implies the highly hydrophobic nature of the material and its low surface energy. This characteristic process assists to obtain a sustainable nanomaterial from waste tyres, contributing to the development of a smart building material.

• Plant Resources
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• 제5권2호
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• pp.95-103
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• 2002

Microscopic techniques were used to observe the microstructure of rice husk. Microscopic examination showed that two main components of husk, lemma and palea consisted of outer epidermis, layers of fibers, vascular bundles, parenchyma cells, and inner epidermis, in sequence from the outer to the inner surface. The outer epidermal walls were extremely thick, highly convoluted and lignified. The underlying fibers were also thick-walled and lignified. Parenchyma cells were thin-walled and unlignified. Inner epidermal cells were also unlignified. The outer surface of both lemma and palea were conspicuously ridged, but the lower surface had a flat appearance. As part of a detailed study to characterize rice husk using microscopic and micro-analytical techniques, distribution of silica was also examined, and is presented elsewhere. Rice husk can potentially be used as a raw material for making composite products and the observations presented here form valuable background information for our future work related to product development.

• Carbon letters
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• 제5권2호
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• pp.75-80
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• 2004

The studies on activated carbon prepared from walnut shell and groundnut shell were undertaken to ascertain the effect of initial state of precursor and activation process on the development of porosity in the resulting activated carbon. Walnut shell based carbon shows the presence of cellular pores while Groundnut shell based carbon shows fibrillar pore structure. The adsorption parameters, characterization of product and scanning electron microscopic studies carried out showed the presence of mainly Micro, Meso and Macro porosity in carbon prepared from Walnut shell while mainly micro porosity was observed in Groundnut shell based activated carbon. An interrelationship between the adsorption efficiency and porosity in terms of quality control parameters, for before and after activation, was validated through the scanning electron microscopic data.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 D
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• pp.1508-1510
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• 1998

Recent development of scanning probe microscope techniques has made it possible to investigate, not only microscopic surface topography, but also physical and chemical properties on the nanometer-scale. The scanning Maxwell-stress microscopy (SMM) is surface characterization tool capable of mapping both the surface topography and electrical properties, such as surface potential, surface charge dielectric constant of thin films with a nanometer-scale resolution by means of the AC voltage driven oscillation of metal coated cantilever. In this study, we observed the surface potential distribution and molecular ordering in thin films. We have demonstrated that the SMM can be used for imaging surface potential distribution over the film surface and also be used for detecting surface changes in thin films. This is first step towards the understanding of electrical phenomena in organic and inorganic materials, biological system with SMM.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2005년도 춘계학술대회 논문집
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• pp.246-251
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• 2005

Laser surface hardening is an effective technique used to improve the tribological properties and also to increase the service life of automobile components such as camshafts, crankshatfs, lorry brake drums and gears. High power $CO_2$ lasers and Nd:YAG lasers are employed for localized hardening of materials and hence are of potential application in the automobile industries. The heat is conducted rapidly into the bulk of the specimen causing self-quenching to occur and the formation of martensitic structure. In this investigation, the microstructure features occurring in Nd:YAG laser hardening SM45C steel are discussed with the use of optical microscopic and scanning electron microscopic analysis. Moreover, This paper describes the optimism of the processing parameters for maximum hardened depth of SM45C steel specimens of 3mm thickness by using CW Nd:YAG laser. Travel speed was varied from 0.6m/min to 1.0m/min. The maximum hardness and case depth fo SM45C steel are 780Hv and 0.4mm by laser hardening.

• Bulletin of the Korean Chemical Society
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• 제32권2호
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• pp.498-502
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• 2011

The divergent synthesis of novel phosphorus-containing dendrimer with 4,4'-sulphonyldiphenol at the core has been accomplished involving simple condensation reactions using $P(O)Cl_3$, $P(S)Cl_3$, 3-amino-phenol, 3-hydroxy-benzaldehyde, and 2-butyn 1, 4-diol. The final compound was a Schiff's base macromolecule possessing 4 imine bonds, 8 acetylenic bonds and 8 OH groups at the periphery. The structures of intermediate compounds were confirmed by IR, NMR ($^1H$, $^{13}C$ and $^{31}P$), LC-Mass and C, H, N analysis. The structure of the final dendrimer (5) was confirmed by IR, NMR ($^1H$, $^{13}C$ and $^{31}P$), MALDI-TOF-MS, and C, H, N analysis. The surface morphological characteristics of the final dendrimer were understood by Scanning Electronic Microscopic study (SEM). The thermal stability of the final dendrimer was studied by TGA/DTA analysis.

• Advances in environmental research
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• 제9권3호
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• pp.215-232
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• 2020

Crude oils are essential source of energy. It is majorly found in geographical locations beneath the earth's surface and crude oil is the main factor for the economic developments in the world. Natural crude oil contains unrefined petroleum composed of hydrocarbons of various molecular weights and it contains other organic materials like aromatic compounds, sulphur compounds, and many other organic compounds. These hydrocarbons are rapidly getting degraded by biosurfactant producing microorganisms. The present study deals with the isolation, purification, and characterization of biosurfactant producing microorganism from oil-contaminated soil. The ability of the microorganism producing biosurfactant was investigated by well diffusion method, drop collapse test, emulsification test, oil displacement activity, and blue agar plate method. The isolate obtained from the oil contaminated soil was identified as Bacillus subtilis. The identification was done by microscopic examinations and further characterization was done by Biochemical tests and 16SrRNA gene sequencing. Purification of the biosurfactant was performed by simple liquid-liquid extraction, and characterization of extracted biosurfactants was done using Fourier transform infrared spectroscopy (FTIR). The degradation of crude oil upon treatment with the partially purified biosurfactant was analyzed by FTIR spectroscopy and Gas-chromatography mass spectroscopy (GC-MS).

• Corrosion Science and Technology
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• 제19권3호
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• pp.138-145
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• 2020

Immersion tests of Alloy 600 were conducted in simulated primary water environments of a pressurized water reactor at 325 ℃ for 10, 100, and 1000 h to obtain insight into effects of surface deformation on internal and intergranular (IG) oxidation behavior through precise characterization using various microscopic equipment. Oxidized samples after immersion tests were covered with polyhedral and filamentous oxides. It was found that oxides were abundant in mechanically ground (MG) samples the most. The number density of surface oxides increased with time irrespective of the method of surface finish. IG oxidation occurred in mechanically polished (MP) and chemically polished (CP) samples with thin internal oxidation layers. However, IG oxidation was suppressed with relatively thick internal oxidation layers in MG samples compared to MP and CP samples, suggesting that MG treatment could increase resistance to primary water stress corrosion cracking (PWSCC) from the standpoint of IG oxidation. As a result, appropriate surface treatment for Alloy 600 could prevent oxygen diffusion into grain boundaries, inhibit IG oxidation, and finally induce its high PWSCC resistance.

• 대한전자공학회논문지
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• 제26권3호
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• pp.124-129
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• 1989

비유전율 및 팽창계수가 낮다는 장점을 갖고 있는 코디에리트는 IC페키지로서 매우 흥미있는 재료이다. 졸겔방법에 의해서 얻어진 코디에리트는 무정형 하얀 가루의 결정으로 이를 약 $900^{circ}C$ 로 열처리 하여, 구운 코디에리트 시료를 만들었다. XPS에 의해서, 코디에리트 시료의 미시적 특성을 연구하였는데, 시료 표면에서는 시료내부의 값들과 비교해 볼때, Mg의 많은 감소와 AI과 Si의 증가를 알 수 있었다. $100{\AA}$ 이하의 시료표면에는 ${pi}$ - 코딩리트 상을 갖는 결정이 존재하고, 시료내부는 적은량의 마그네슘 알루미나트($MgAl_2O_4$)가 존재하였다. 한편 코디에리트 표면에서 열처리에 다른 화학적 변화가 없는 것을 알 수 있었다.

• 한국잠사곤충학회지
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• 제31권2호
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• pp.113-120
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• 1989

가잠에서 분리된 새로운 미포자충(S85)의 특성을 구명하기 위한 일환으로 포자의 미세구조를 전자현미경으로 관찰한 결과는 아래와 같다. 1. 포자는 전자밀도가 상이한 3층의 피각으로 되어 있으며 그 외각은 전자밀도가 높고 요철이 다소 심한 편이고 내각은 전자밀도가 낮으며 포자피각 두께의 대부분을 차지하였다. 2. 극막층은 그 배열이 조밀하고 성긴 두 부분의 Lamellae 구조로 되어 있었다. 3. 극사는 13개의 coil을 가지고 있으며 전자밀도가 서로 다른 8개의 동심원층으로 되어 있었다. 4. 포자는 1개의 핵을 가지고 있으며 다포자아막을 형성하고 막내에 16개 이상의 포자를 가지고 있었다. 5. 포자의 표면은 거칠고 주름이 있으며 다포자 아막은 고무풍선처럼 생긴 얇은 막구조로서 표면에는 약간의 주름이 있었다.