• Title/Summary/Keyword: Carbon/carbon-based materials

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Geochemical Evidence for Spatial Paleoproductivity Variations the Northwest Pacific (Shikoku Basin) during the Last Glacial Maximum

  • Hyun, Sang-Min;Ahagon, Naogazu;Saito, Saneatu;Ikehara, Minoru;Oba, TadamichI;Taira, Asahiko
    • Journal of the korean society of oceanography
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    • 제31권4호
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    • pp.207-216
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    • 1996
  • A geochemical study of three piston cores (ST.4, ST.6 and ST.20) taken from the Northwest Pacific (eastern edge of Shikoku Basin) provides information about changes in surface water paleoproductivity and sedimentation during the last 127 kys. Paleoproductivity variations were estimated on the basis of total organic carbon content and carbonate mass accumulation rate. The paleoproductivity based on total organic carbon shows significant spatial variations between glacial and interglacial periods. During the last glacial maximum (LGM) paleoproductivity increased about 1.5 times with deglaciation decrease compared with those of the Holocene at inner side of the Shikoku Basin (ST.4 and ST.6). On the other hand, paleoproductivity at outer side of Shikoku Basin (ST.20) indicating not distinctive increase but deglaciation increase. The C/N ratios fall below 10 for cores ST.4 and ST.6, but C/N ratios between 100 ka and 80 ka in ST.20 which show around 10 or larger values suggest a predominance of marine organic carbon with some admixture of terrigenous materials. The carbonate mass accumulation rate of three cores show different patterns of calcareous record with respect to organic carbon based paleoproductivity variation. In the inner side of Shikoku Basin (ST.4 and ST.6) the carbonate mass accumulation rate decreased during last glacial maximum, and significant increase of carbonate mass accumulation rate is recognized at outer side of Shikoku Basin (ST.20). Thus, this set of data reveals that spatial paleoproductivity variations between inner and outer side of Shikoku Basin during the glacial and interglacial periods.

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Biodegradation of Endosulfan by Klebsiella oxytoca KE-8 Immobilized on Activated Carbon

  • Jo, Min-Sub;Lee, Jung-Bok;Kim, Jang-Eok;Sohn, Ho-Yong;Jeon, Chun-Pyo;Choi, Chung-Sig;Kwon, Gi-Seok
    • 한국환경농학회지
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    • 제29권2호
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    • pp.176-183
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    • 2010
  • Endosulfan degrading ability of Klebsiella oxytoca KE-8 immobilized by entrapment with activated carbon was examined. Endosulfan degradation by the immobilized bacterial strains on several different activated carbon based support materials was investigated. Based on results, activated carbon ($8\times30$ mesh) was chosen as a support material. The immobilized Klebsiella oxytoca KE-8 with the cell density of 4 mg $g^{-1}$ (dry weight) degraded 22.18 ug $ml^{-1}$ endosulfan within 5 days at pH 7.0, $30^{\circ}C$ in batch shake flask cultures. Also, we an experimented recycle packed bed column mode and continuous packed bed column mode for endosulfan degradation. Under optimum operation condition, the immobilized cells in a laboratory scale pack bed column with support beads were able to degrade endosulfan completely in defined minimal salt medium at a maximum rate of 129.6 ug $ml^{-1}$ per day. Moreover, the endosulfan degradation activity could be demonstrated at $4^{\circ}C$ for one month without significant decrease in activity. Results of this study suggest that immobilized cells of Klebsiella oxytoca KE-8 might be applicable to endosulfan contaminated site.

Free-standing Three Dimensional Graphene Incorporated with Gold Nanoparticles as Novel Binder-free Electrochemical Sensor for Enhanced Glucose Detection

  • Bui, Quoc Bao;Nguyen, Dang Mao;Nguyen, Thi Mai Loan;Lee, Ku Kwac;Kim, Hong Gun;Ko, Sang Cheol;Jeong, Hun
    • Journal of Electrochemical Science and Technology
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    • 제9권3호
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    • pp.229-237
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    • 2018
  • The electrochemical sensing performance of metal-graphene hybrid based sensor may be significantly decreased due to the dissolution and aggregation of metal catalyst during operation. For the first time, we developed a novel large-area high quality three dimensional graphene foam-incorporated gold nanoparticles (3D-GF@Au) via chemical vapor deposition method and employed as free-standing electrocatalysis for non-enzymatic electrochemical glucose detection. 3D-GF@Au based sensor is capable to detect glucose with a wide linear detection range of $2.5{\mu}M$ to 11.6 mM, remarkable low detection limit of $1{\mu}M$, high selectivity, and good stability. This was resulted from enhanced electrochemical active sites and charge transfer possibility due to the stable and uniform distribution of Au NPs along with the enhanced interactions between Au and GF. The obtained results indicated that 3D-GF@Au hybrid can be expected as a high quality candidate for non-enzymatic glucose sensor application.

Mechanical buckling of FG-CNTs reinforced composite plate with parabolic distribution using Hamilton's energy principle

  • Tayeb, Tayeb Si;Zidour, Mohamed;Bensattalah, Tayeb;Heireche, Houari;Benahmed, Abdelillah;Bedia, E.A. Adda
    • Advances in nano research
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    • 제8권2호
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    • pp.135-148
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    • 2020
  • The incorporation of carbon nanotubes in a polymer matrix makes it possible to obtain nanocomposite materials with exceptional properties. It's in this scientific background that this work was based. There are several theories that deal with the behavior of plates, in this research based on the Mindlin-Reissner theory that takes into account the transversal shear effect, for analysis of the critical buckling load of a reinforced polymer plate with parabolic distribution of carbon nanotubes. The equations of the model are derived and the critical loads of linear and parabolic distribution of carbon nanotubes are obtained. With different disposition of nanotubes of carbon in the polymer matrix, the effects of different parameters such as the volume fractions, the plate geometric ratios and the number of modes on the critical load buckling are analysed and discussed. The results show that the critical buckling load of parabolic distribution is larger than the linear distribution. This variation is attributed to the concentration of reinforcement (CNTs) at the top and bottom faces for the X-CNT type which make the plate more rigid against buckling.

3미터급 카본 카약의 저항성능 및 구조 안전성 연구 (Resistance and Structural Safety of a 3M Carbon Fibier-based Kayak)

  • 서광철;이경우;박주신
    • 해양환경안전학회지
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    • 제25권4호
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    • pp.482-488
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    • 2019
  • 최근 수상 레저 사업장과 레저기구의 개수는 지속해서 성장하고 있다. 수상레저기구 중에서도 카약과 카누의 보급률이 크게 증가하고 있다. 기존에는 주로 FRP 재료를 사용하여 제작하였으나, 지구온난화, 천연자원 고갈 등의 문제로 인해 청정에너지 및 신재생 에너지에 대한 필요성이 대두됨에 따라 탄소섬유에 대한 수요도 빠르게 증가하고 있다. 본 연구에서는 이러한 사회적인 변화 의식에 부합하기 위하여, 탄소섬유를 적용한 보급형 카약을 설계하고, 제품의 신뢰성을 검증하기 위하여 저항성능 및 구조 안전성 평가를 수행하였다. 속도 변화에 따른 압력저항과 마찰저항 변화를 검토하였으며, 속도 2.6 m/s 이상에서는 압력저항이 크게 증가하면서 전체저항이 커지는 현상이 발생한다. 현재 카약 구조는 운용 시 고려할 수 있는 설계하중을 고려 시, 충분한 안전율을 갖고 있음을 확인하였다.

A study of glass and carbon fibers in FRAC utilizing machine learning approach

  • Ankita Upadhya;M. S. Thakur;Nitisha Sharma;Fadi H. Almohammed;Parveen Sihag
    • Advances in materials Research
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    • 제13권1호
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    • pp.63-86
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    • 2024
  • Asphalt concrete (AC), is a mixture of bitumen and aggregates, which is very sensitive in the design of flexible pavement. In this study, the Marshall stability of the glass and carbon fiber bituminous concrete was predicted by using Artificial Neural Network (ANN), Support Vector Machine (SVM), Random Forest (RF), and M5P Tree machine learning algorithms. To predict the Marshall stability, nine inputs parameters i.e., Bitumen, Glass and Carbon fibers mixed in 100:0, 75:25, 50:50, 25:75, 0:100 percentage (designated as 100GF:0CF, 75GF:25CF, 50GF:50 CF, 25GF:75CF, 0GF:100CF), Bitumen grade (VG), Fiber length (FL), and Fiber diameter (FD) were utilized from the experimental and literary data. Seven statistical indices i.e., coefficient of correlation (CC), mean absolute error (MAE), root mean squared error (RMSE), relative absolute error (RAE), root relative squared error (RRSE), Scattering index (SI), and BIAS were applied to assess the effectiveness of the developed models. According to the performance evaluation results, Artificial neural network (ANN) was outperforming among other models with CC values as 0.9147 and 0.8648, MAE values as 1.3757 and 1.978, RMSE values as 1.843 and 2.6951, RAE values as 39.88 and 49.31, RRSE values as 40.62 and 50.50, SI values as 0.1379 and 0.2027 and BIAS value as -0.1 290 and -0.2357 in training and testing stage respectively. The Taylor diagram (testing stage) also confirmed that the ANN-based model outperforms the other models. Results of sensitivity analysis showed that the fiber length is the most influential in all nine input parameters whereas the fiber combination of 25GF:75CF was the most effective among all the fiber mixes in Marshall stability.

탄소섬유 분사형 복합재 유지보수 로봇의 보수성능평가 (Performance Evaluation for Repair of Composite Maintenance Robot Using Carbon Fiber Spray Method)

  • 송근수;천대한;이재열;신광복
    • Composites Research
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    • 제37권2호
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    • pp.76-85
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    • 2024
  • 본 논문에서는 보수를 위해 생성된 혼합물을 손상부위에 자동으로 분사하여 보수하는 탄소섬유 분사형 복합재 유지보수 로봇을 개발하였다. 로봇 개발을 위해 불연속 탄소섬유와 에폭시 수지(Epoxy resin) 및 경화제가 혼합된 보수용 혼합물을 손상부위에 분사한 뒤 경화시키는 보수공정을 개발하였다. 이후, 개발된 보수공정의 자동화를 위해 협동로봇(Collaborative robot)을 기반으로 보수용 혼합물을 손상부위에 자동으로 흡입 및 분사하는 말단장치(End of arm tool, EOAT)를 개발하였다. 개발된 로봇의 보수성능평가를 위해 복합재 인장시험 규정 ASTM D3039에 의거하여 0° 및 90°일방향 시편 제작 및 시험을 수행하였다. 시험은 손상되지 않은 시편, 손상된 시편, 그리고 손상 후 로봇에 의해 자동으로 보수된 시편에 대해 수행되었다. 시험 결과, 0와 90° 시편에 대해 각각 보수 후 약 10%와 90%의 인장강도 회복율이 확인되어 개발된 탄소섬유 분사형 복합재 보수 로봇의 보수성능을 검증하였다.

졸겔법으로 제조한 탄소피복된 SiOx/ZnO 복합체의 합성 및 전기화학적 특성 (Synthesis and Electrochemical Characteristics of Carbon Coated SiOx/ZnO Composites by Sol-gel Method)

  • 백광용;정상문;나병기
    • 청정기술
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    • 제22권4호
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    • pp.308-315
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    • 2016
  • 수명특성이 우수한 실리콘 음극재를 제조하기 위해 졸겔법을 통해 $SiO_x/ZnO$ 복합체를 제조하였고, 제조된 복합체는 PVC를 탄소 전구체로 하여 탄소를 피복하였다. 복합체에 포함된 ZnO를 HCl로 제거하여 내부에 빈 공간을 만들어 충 방전에 따른 실리콘의 부피변화를 완화할 수 있게 하였다. 합성된 복합체의 결정구조와 형상을 파악하기 위해 XRD, SEM, TEM 분석을 실시하였다. 탄소 피복된 복합체에 포함된 탄소함량을 TGA를 통해 알아보았으며, 복합체의 기공구조를 확인하기 위해 BET 비표면적 분석과 BJH 기공분포를 확인하였다. 탄소의 추가로 향상된 전기전도성을 측정하였으며, 전기화학적 특성은 AC 임피던스 측정과 충 방전 및 수명특성을 확인하였다. $SiO_x/ZnO$시료에 탄소를 피복할 경우에 전기전도도가 증가하였으며, 방전용량도 증가하였다. 염산으로 ZnO를 제거한 시료의 경우에 표면적은 증가하였으나, 전지의 방전용량은 오히려 감소하였다. 탄소를 피복하지 않은 $SiO_x/ZnO$ 시료의 경우에 방전용량이 매우 낮았으며, 탄소를 피복한 후의 시료는 높은 충방전용량을 나타내었다. 수명특성의 경우, $C-SiO_x/ZnO$ 복합체(Zn : Si : C = 1 : 1 : 8)가 0.2 C의 전류량에서 50 사이클에서 $815mAh\;g^{-1}$의 용량으로 기존 흑연계 음극재보다 높은 용량을 나타내었다.