Theoretical Investigation of Lithium-Atom Insertion into Ultra-Small Diameter Carbon Nanotubes

Anurak Udomvech,Teerakiat Kerdcharoen 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

Computations of Li intercalation into ultra-small single-walled carbon nanotubes have been car- ried out within the framework of the rst-principles density functional calculation. The energy and the structural properties of two Li atoms as a function of distance along the longitudinal axis of (3,3), (4,2) and (5,0) nanotubes have been calculated. We found that Li atoms could be easily pulled into the interior of (3,3) and (4,2) nanotubes whereas a small energy barrier existed at the open-mount of (5,0) tube. The zigzag (5,0) nanotube allows Li-Li to localize near the tube center, forming a Li2 cluster inside the nanotube. In contrast, Li atoms prefer to locate near the open mounts of the armchair (3,3) tube. In case of a (4,2) nanotube, no preferential location is found, as described by the at potential energy prole. The intercalated atoms aect the geometric pa- rameters at the central region more than the rest of the nanotube. These results provide evidence that chirality plays a crucial role in Li-tube interactions, especially for ultra-small nanotubes, which suggests that appropriate tubule chiralities are needed if ecient anode materials are to be used in Li batteries. Computations of Li intercalation into ultra-small single-walled carbon nanotubes have been car- ried out within the framework of the rst-principles density functional calculation. The energy and the structural properties of two Li atoms as a function of distance along the longitudinal axis of (3,3), (4,2) and (5,0) nanotubes have been calculated. We found that Li atoms could be easily pulled into the interior of (3,3) and (4,2) nanotubes whereas a small energy barrier existed at the open-mount of (5,0) tube. The zigzag (5,0) nanotube allows Li-Li to localize near the tube center, forming a Li2 cluster inside the nanotube. In contrast, Li atoms prefer to locate near the open mounts of the armchair (3,3) tube. In case of a (4,2) nanotube, no preferential location is found, as described by the at potential energy prole. The intercalated atoms aect the geometric pa- rameters at the central region more than the rest of the nanotube. These results provide evidence that chirality plays a crucial role in Li-tube interactions, especially for ultra-small nanotubes, which suggests that appropriate tubule chiralities are needed if ecient anode materials are to be used in Li batteries.

Effect of Structural Transformation on the Gas-Sensing Properties of Phthalocyanine Thin Films

Sureeporn Uttiya,Teerakiat Kerdcharoen,Santi Vatanayon,Sirapat Pratontep 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

We report on the use of zinc tetra-tertiary-butyl phthalocyanine (ZnTTBPc) thin lms as an optical gas sensor. The ZnTTBPc lms were fabricated by spin-coating onto glass substrates. The response of the ZnTTBPc lms to various alcohols was monitored by using optical absorption spectroscopy under both static and dynamic conditions. The gas-sensing capability of the films was substantially improved by thermal annealing of the spin-coated films at 340℃. This procedure was found to eliminate irreversible changes in the absorption spectra after exposure to test alcohols. X-ray diffraction and atomic force microscopy measurements related this effect to the structural transformation of the ZnTTBPc lms from an amorphous to a crystalline phase. The strongest gas- sensing response of the annealed lms was observed for methanol. The results are in good agreement with the density functional theory (DFT) calculations, which indicate that the interaction between the Zn atom and the OH group of methanol is the strongest among the test alcohols. We report on the use of zinc tetra-tertiary-butyl phthalocyanine (ZnTTBPc) thin lms as an optical gas sensor. The ZnTTBPc lms were fabricated by spin-coating onto glass substrates. The response of the ZnTTBPc lms to various alcohols was monitored by using optical absorption spectroscopy under both static and dynamic conditions. The gas-sensing capability of the films was substantially improved by thermal annealing of the spin-coated films at 340℃. This procedure was found to eliminate irreversible changes in the absorption spectra after exposure to test alcohols. X-ray diffraction and atomic force microscopy measurements related this effect to the structural transformation of the ZnTTBPc lms from an amorphous to a crystalline phase. The strongest gas- sensing response of the annealed lms was observed for methanol. The results are in good agreement with the density functional theory (DFT) calculations, which indicate that the interaction between the Zn atom and the OH group of methanol is the strongest among the test alcohols.

Soil sensing survey robots based on electronic nose

Theerapat Pobkrut,Teerakiat Kerdcharoen 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10

Nowadays autonomous robots are used in many filed of agriculture for increasing efficiency, and especially reducing the cost of the scarce human labor. Mobile ground robot and flying drone can be used to survey the farmland collecting necessary information such as ambient and crop conditions, soil fertility, pest and disease, etc. In this work, we have implemented an electronics nose (e-nose) based on metal oxide gas sensors installed on a mobile robot for detection of organic volatile compounds contained in the soil surface to examine the fertility of soil. Farmers can use such information to manage crops fertilizing or watering. To demonstrate this idea, we have mapped the soil volatiles at different places and having different types of soil, using laboratory-made portable e-nose and mobile e-nose robot. Therefore, the experiment was separated into 2 parts. The first part was to collect soils from different places and to measure the soil volatiles using portable e-nose that has eight metal-oxide gas sensors, in order to classify and confirm the difference between each sample. Secondly, the array of six gas sensors was then installed on a semi-autonomous six-wheeled robot chassis in order to measure real situations of soil surface located at four different places. It was found that both portable and robotized e-noses can identify and confirm the difference of soil volatiles when using principal component analysis (PCA) as pattern recognition.

The geometrical and electronic structures of open-end fully functionalized single-walled carbon nanotubes

Chatchawal Wongchoosuk,Anurak Udomvech,Teerakiat Kerdcharoen 한국물리학회 2009 Current Applied Physics Vol.9 No.3

We have investigated the geometrical and electronic structures of open-end single-walled carbon nanotubes (SWNTs) having chemically modified tips, using semi-empirical AM1 and density functional theory methods. The hydroxyl (–OH), carboxyl (–COOH) and amide (–CONH2) functional groups were used to saturate the open-ends of nanotubes. The effects of functional groups were studied by comparison with the pristine tubes, of which the tubular lengths vary from two to ten unit-cells (40Å). The results show that the C–C bond lengths of all model tubes are only slightly different, and the behavior of converging bond lengths in COOH– and CONH2-SWNTs is very similar to the pristine tube. Tip functionalization alters the frontier orbitals of the pristine tube, but these effects seem to rapidly decrease as the tubule becomes longer. In general, it can be concluded that the geometrical and electronic structures of pristine tubes after tube-end ‘‘full” functionalization will be preserved, hence supporting that more real-world ‘‘partially” functionalized SWNTs can be used in the same way as the pristine version in most application areas. We have investigated the geometrical and electronic structures of open-end single-walled carbon nanotubes (SWNTs) having chemically modified tips, using semi-empirical AM1 and density functional theory methods. The hydroxyl (–OH), carboxyl (–COOH) and amide (–CONH2) functional groups were used to saturate the open-ends of nanotubes. The effects of functional groups were studied by comparison with the pristine tubes, of which the tubular lengths vary from two to ten unit-cells (40Å). The results show that the C–C bond lengths of all model tubes are only slightly different, and the behavior of converging bond lengths in COOH– and CONH2-SWNTs is very similar to the pristine tube. Tip functionalization alters the frontier orbitals of the pristine tube, but these effects seem to rapidly decrease as the tubule becomes longer. In general, it can be concluded that the geometrical and electronic structures of pristine tubes after tube-end ‘‘full” functionalization will be preserved, hence supporting that more real-world ‘‘partially” functionalized SWNTs can be used in the same way as the pristine version in most application areas.

Design of Mobile Robot for Real World Application in Path Planning Using ZigBee Localization

Natthapol Watthanawisuth,Adisorn Tuantranont,Teerakiat Kerdcharoen 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10

This paper proposes a new path planning algorithm for a mobile robot applicable for realistic uses in farmland, which utilizes ZigBee localization, GPS and simple path learning from the GPS-Tractor tracking. The aim of this work is to verify a possibility in applying the ZigBee localization with GPS to estimate the tracking position of a mobile robot working in a farmland. To enhance robot mobility in a large area, human-supervised decision is implicitly incorporated into the path guiding using tracking data from the GPS tractor. Such development combining other systems to help in path guiding instead of operating only the standalone software on mobile robot could reduce the complexity of the path planning in complex farmland. We have applied this technology in a real-world situation at GranMonte Vineyard and Winery, Thailand.

Effects of Steric Anthracene Moieties and Keto Defects on Photophysics and Color Stability of Poly(9,9-di(2-ethylhexyl)fluorene-stat-anthracene) in Different Local Environments

Rakchart Traiphol,Thanutpon Pattanatornchai,Toemsak Srikhirin,Teerakiat Kerdcharoen,Tanakorn Osotchan 한국고분자학회 2010 Macromolecular Research Vol.18 No.12

UV/vis absorption and photoluminescence (PL) spectroscopy were used to examine the photophysical properties of statistical copolymers, poly(9,9-di(2-ethylhexyl)fluorene-stat-anthracene), with the mole ratio of the anthracene group ranging from 0 to 20%. The incorporation of the anthracene group into the conjugated backbone of the polyfluorene affected the PL pattern and quantum yield of the isolated chain in a dilute solution. An investigation of the photophysical properties in solvent-nonsolvent system revealed the formation of low-energy non-emissive and emissive aggregates. The quantity of these aggregated species depends significantly on the mole ratio of anthracene group in the polymer backbone. The existence of only 5 mol% of anthracene in the copolymer causes significant suppression of the well-known green emission (λ~525 nm). However, a large quantity of non-emissive aggregates indicated by the red-shift peak at ~415 nm in absorption spectra still formed. Increasing the mole ratio of the anthracene group to 20% suppressed both types of aggregates. Measurements of the absorption and PL spectra in the thin films showed consistent results. Although annealing of the homopolymer polyfluorene films at 150 oC in a vacuum oven caused a drastic increase in green emission, only a slight change was detected in the PL spectra of the copolymers. The presence of oxygen during annealing promoted the green emission of the polymer films.

Bacillus thuringiensis Cry4A and Cry4B Mosquito-larvicidal Proteins: Homology-based 3D Model and Implications for Toxin Activity

( Chanan Angsuthanasombat ),( Panapat Uawithya ),( Somphob Leetachewa ),( Walairat Pornwiroon ),( Puey Ounjai ),( Teerakiat Kerdcharoen ),( Gerd Katzenmeier ),( Sakol Panyim ) 생화학분자생물학회 2004 BMB Reports Vol.37 No.3

Three-dimensional (3D) models for the 65-kDa activated Cry4A and Cry4B δ-endotoxins from Bacillus thuringiensis subsp, israelensis that are specifically toxic to mosquito-larvae were constructed by homology modeling, based on atomic coordinates of the Cry1Aa and Cry3Aa crystal structures. They were structurally similar to the known structures, both derived 3D models displayed a three-domain organization: the N-terminal domain (I) is a seven-helix bundle, while the middle and C-terminal domains are primarily comprise of anti-parallel β-sheets. Circular dichroism spectroscopy confirmed the secondary structural contents of the two homology-based Cry4 structures. A structural analysis of both Cry4 models revealed the following: (a) Residues Arg-235 and Arg-203 are located in the interhelical 5/6 loop within the domain I of Cry4A and Cry4B, respectively. Both are solvent exposed. This suggests that they are susceptible to tryptic cleavage. (b) The unique disulphide bond, together with a proline-rich region within the long loop connecting α4 and α5 of Cry4A, were identified. This implies their functional significance for membrane insertion. (c) Significant structural differences between both models were found within domain 11 that may reflect their different activity spectra. Structural insights from this molecular modeling study would therefore increase our understanding of the mechanic aspects of these two closely related mosquito-larvicidal proteins.

Bacillus thuringiensis Cry4A and Cry4B Mosquito-larvicidal Proteins: Homology-based 3D Model and Implications for Toxin Activity

Angsuthanasombat, Chanan,Uawithya, Panapat,Leetachewa, Somphob,Pornwiroon, Walairat,Ounjai, Puey,Kerdcharoen, Teerakiat,Katzenmeier, Gerd,Panyim, Sakol Korean Society for Biochemistry and Molecular Biol 2004 Journal of biochemistry and molecular biology Vol.37 No.3

Three-dimensional (3D) models for the 65-kDa activated Cry4A and Cry4B $\delta$-endotoxins from Bacillus thuringiensis subsp. israelensis that are specifically toxic to mosquito-larvae were constructed by homology modeling, based on atomic coordinates of the Cry1Aa and Cry3Aa crystal structures. They were structurally similar to the known structures, both derived 3D models displayed a three-domain organization: the N-terminal domain (I) is a seven-helix bundle, while the middle and C-terminal domains are primarily comprise of anti-parallel $\beta$-sheets. Circular dichroism spectroscopy confirmed the secondary structural contents of the two homology-based Cry4 structures. A structural analysis of both Cry4 models revealed the following: (a) Residues Arg-235 and Arg-203 are located in the interhelical 5/6 loop within the domain I of Cry4A and Cry4B, respectively. Both are solvent exposed. This suggests that they are susceptible to tryptic cleavage. (b) The unique disulphide bond, together with a proline-rich region within the long loop connecting ${\alpha}4$ and ${\alpha}5$ of Cry4A, were identified. This implies their functional significance for membrane insertion. (c) Significant structural differences between both models were found within domain II that may reflect their different activity spectra. Structural insights from this molecular modeling study would therefore increase our understanding of the mechanic aspects of these two closely related mosquito-larvicidal proteins.