Maluangnont, Tosapol

Preferred name

Alternative Name

Maluangnont, T.

Main Affiliation

Integrated Innovative Technology

tosapol.ma@kmitl.ac.th

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Electrical and dielectric properties of barium titanate–polydimethylsiloxane nanocomposite with 0-3 connectivity modified with carbon nanotube (CNT)
(2019-01-02)
Nawanil, Chanisa
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Makcharoen, Worawut
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Khaosa-Ard, Krittanat
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Maluangnont, Tosapol
;
Vittayakorn, Wanwilai
This study explored the preparation and electrical properties of 0–3 barium titanate/polydimethylsiloxane nanocomposites by dispersing barium titanate nanoparticles (BaTiO<inf>3</inf>; BT) into the polydimethylsiloxane (PDMS) matrix phase. The effect of barium titanate nanoparticles on electrical properties has been investigated systematically, and the relative permittivity of nanocomposites was found to increase significantly with increasing barium titanate content. Different theoretical models were used to predict the dielectric constant of these composites and compare their experimental value with the theoretical value in order to find an appropriate equation. The result indicated that the dielectric properties of composites are influenced not only by relative permittivity of the components but also dependence on interactions between ceramics and polymers. Furthermore, the preparation and dielectric properties of BT/PDMS nanocomposites modified with carbon nanotube (CNT) were also studied. The dielectric results demonstrate that adding CNT can enhance the relative permittivity of the BT/PDMS composite via improvement of dispersion and distribution of the BT nanoparticles in the PDMS matrix phase. Moreover, the electrical outputs from the BT/PDMS/CNT nanocomposites generator were measured under periodic knocking. The nanocomposites innovatively expand the feasibility of self-powered energy systems for smart sensor and energy harvesting applications.
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Ti0.8O2 nanosheets inhibit lung cancer stem cells by inducing production of superoxide anion
(2019-04-01)
Petpiroon, Nalinrat
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Bhummaphan, Narumol
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Soonnarong, Rapeepun
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Chantarawong, Wipa
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Maluangnont, Tosapol
Recent research into the cancer stem cell (CSC) concept has driven progress in the understanding of cancer biology and has revealed promising CSC-specific targets for drug discovery efforts. As malignancies of lung cancer have been shown to be strongly associated with activities of CSCs, we examined the effects of Ti<inf>0.8</inf>O<inf>2</inf> nanosheets on these cells. Here we show that the nanosheets target lung CSCs but not normal primary dermal papilla (DP) stem cells. Whereas Ti<inf>0.8</inf>O<inf>2</inf> caused a dramatic apoptosis along with a decrease in CSC phenotypes, in primary human DP cells such effects of nanosheets have been minimal. Nanosheets reduced the ability of lung cancer cells to generate three-dimensional tumor spheroids, lung CSC markers (CD133 and ALDH1A1), and CSC transcription factors (Nanog and Oct-4). Ti<inf>0.8</inf>O<inf>2</inf> nanosheets reduced CSC signaling through mechanisms involving suppression of protein kinase B (AKT) and Notch-1 pathways. In addition, the nanosheets inhibited the migration and invasive activities of lung cancer cells and reduced epithelial-to-mesenchymal transition (EMT) markers as N-cadherin, vimentin, and Slug, as well as metastasis-related integrins (integrin-av and integrin-b1). Importantly, we found that the selectivity of the Ti<inf>0.8</inf>O<inf>2</inf> nanosheets in targeting cancer cells was mediated by induction of cellular superoxide anion in cancerous but not normal cells. Inhibition of nanosheet-induced superoxide anion restored the suppression of CSC and EMT in cancer cells. These findings demonstrate a promising distinctive effect of Ti<inf>0.8</inf>O<inf>2</inf> nanosheets on lung CSC that may lead to opportunities to use such a nanomaterial in cancer therapy.
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Production of liquid fuel from palmitic acid over nanocrystalline CeO2-based catalysts with minimal use of H2
(2017-01-01)
Maluangnont, Tosapol
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Dararat, Chalinee
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Kulrat, Teerapong
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Soontontaweesub, Surachet
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Anothaiwalaikul, Thitima
The deoxygenation of palmitic acid into diesel-range hydrocarbons can be promoted over nanocrystalline ceria-based catalysts under atmospheric N<inf>2</inf> or 10% H<inf>2</inf>/N<inf>2</inf> in a fixed-bed flow reactor at 400 °C. Oxygen vacancy sites are active for ketonization of palmitic acid to C<inf>31</inf> ketone and also subsequent cracking of the formed ketone to hydrocarbons. The 22–31% selectivity of C<inf>9</inf> to C<inf>17</inf> liquid hydrocarbons can be achieved at 100% palmitic acid conversion. The deoxygenation under N<inf>2</inf> can be facilitated, presumably by hydrogen transfer from coke precursors. Catalytic activity of ceria-based catalysts can be tuned by pretreatment conditions, type of a carrier gas, or lattice modification.
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Giant dielectric constants in K0.8M0.4Ti1.6O4 (M = Ni, Zn) lepidocrocite-type layered titanate ceramics
(2019-01-02)
Maluangnont, Tosapol
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Vittayakorn, Naratip
We reported herein the temperature-dependent dielectric properties of K<inf>0.8</inf>M<inf>0.4</inf>Ti<inf>1.6</inf>O<inf>4</inf> (M = Ni, Zn) lepidocrocite titanate ceramics at the frequency f of 103, 104 and 105 Hz. This titanate is an example of layered alkali titanium oxides possessing two-dimensional (2D) sheets of edge-shared TiO<inf>6</inf> octahedra, in contrast to other widely studied materials with mostly corner-shared TiO<inf>6</inf> motifs. The giant dielectric constants ε′ ∼104 and the dielectric losses tan δ ∼ 0.5–2 were obtained upon heating from RT to 250 °C. These values in our water-free ceramics are comparable to those previously reported in lepidocrocite titanate and related structures containing up to 15%wt water. The results were explained considering (i) Maxwell-Wagner polarization of interlayer species, and (ii) the possible formation of internal barrier layer capacitors (IBLCs) via the oxidized surfaces.
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Surface and interlayer base-characters in lepidocrocite titanate: The adsorption and intercalation of fatty acid
(2016-06-01)
Maluangnont, Tosapol
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Arsa, Pornanan
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Limsakul, Kanokporn
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Juntarachairot, Songsit
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Sangsan, Saithong
While layered double hydroxides (LDHs) with positively-charged sheets are well known as basic materials, layered metal oxides having negatively-charged sheets are not generally recognized so. In this article, the surface and interlayer base-characters of O2- sites in layered metal oxides have been demonstrated, taking lepidocrocite titanate K<inf>0.8</inf>Zn<inf>0.4</inf>Ti<inf>1.6</inf>O<inf>4</inf> as an example. The low basicity (0.04 mmol CO<inf>2</inf>/g) and low desorption temperature (50-300 °C) shown by CO<inf>2</inf>- TPD suggests that O2- sites at the external surfaces is weakly basic, while those at the interlayer space are mostly inaccessible to CO<inf>2</inf>. The liquid-phase adsorption study, however, revealed the uptake as much as 37% by mass of the bulky palmitic acid (C<inf>16</inf> acid). The accompanying expansion of the interlayer space by ~0.1 nm was detected by PXRD and TEM. In an opposite manner to the external surfaces, the interlayer O2- sites can deprotonate palmitic acid, forming the salt (i.e., potassium palmitate) occluded between the sheets. Two types of basic sites are proposed based on ultrafast 1H MAS NMR and FTIR results. The interlayer basic sites in lepidocrocite titanate leads to an application of this material as a selective and stable two-dimensional (2D) basic catalyst, as demonstrated by the ketonization of palmitic acid into palmitone (C<inf>31</inf> ketone). Tuning of the catalytic activity by varying the type of metal (Zn, Mg, and Li) substituting at TiIV sites was also illustrated.
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High-Performance Hybridized Composited-Based Piezoelectric and Triboelectric Nanogenerators Based on BaTiO3/PDMS Composite Film Modified with Ti0.8O2 Nanosheets and Silver Nanopowders Cofillers
(2019-05-28)
Sriphan, Saichon
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Charoonsuk, Thitirat
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Maluangnont, Tosapol
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Vittayakorn, Naratip
In order to commercialize the rapidly developing technology of energy harvesters, the following devices need to be developed further for enhancing output performance, flexibility, scalability, facile fabrication, and cheaper price. The composite-based triboelectric nanogenerator (CTENG), which contains the above properties, is a promising technology that has attracted special interest for a decade. Focus has been placed on the hybrid concept between the composite-based piezoelectric nanogenerator (CPENG) and CTENG in order to enhance CTENG efficiency. This study presented a high-performance hybridized CPENG and CTENG device, which operated from the composite film of Ti<inf>0.8</inf>O<inf>2</inf> nanosheets (Ti NSs)/silver nanoparticles (Ag NPs) co-doped BaTiO<inf>3</inf> nanopowders (BT NPOs) inside the polydimethylsiloxane (PDMS) host. The 0.3 vol % of Ti NSs and 1.5 vol % of Ag NPs exhibited the optimum harvesting performance in all compositions, with an output voltage and current density reaching approximately 150 V and 0.32 μA/cm2, respectively. Their harvesting performance was approximately 60 and 32 times higher than that of the CPENG constructed from pure PDMS. In addition, practical demonstration of the proposed device was investigated. The hybridized CPENG and CTENG device could operate in a long-term cyclic operation, charge the capacitor for storing energy, and also drive LEDs to brighten. This work suggested facile device fabrication and made a guideline to develop high-performance nanogenerators, which is crucial for device development and practical usage in the future.
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Local structure of stoichiometric and oxygen-deficient A 2Ti6O13 (A = Li, Na, and K) studied by X-ray absorption spectroscopy and first-principles calculations
(2018-10-21)
Kanchanawarin, Jarin
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Limphirat, Wanwisa
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Promchana, Pratya
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Sooknoi, Tawan
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Maluangnont, Tosapol
Oxygen vacancy defects (V<inf>O</inf>) in Ti-based oxides play important roles in catalytic processes despite limited knowledge regarding their formation and characterization. Here, we demonstrate the use of X-ray absorption spectroscopy (XAS) measurements to compare the relative proportion of V<inf>O</inf> defects in as-grown alkali hexatitanate A<inf>2</inf>Ti<inf>6</inf>O<inf>13</inf> (A = Li, Na, K). Both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) regions were studied. The similarity of measured XANES spectra of Ti K-edge in all samples indicates the presence of (Ti4+)O<inf>6</inf> units in good agreement with reported X-ray diffraction results. The small influence of cations A at the tunnel was observed and can be well reproduced in the simulated spectra. In addition, we present a semi-quantitative approach to intuitively determine the content of V<inf>O</inf> defects in oxygen-deficient K<inf>2</inf>Ti<inf>6</inf>O<inf>13-x</inf> by in situ time-resolved XAS measurements under reducing conditions (10%H<inf>2</inf>/Ar, 50-650 °C). The in situ XANES measurements indicate that the oxidation state of bulk Ti remains the same as the as-grown sample, i.e., 4+, at elevated temperatures. By in situ EXAFS measurements, the relative number of V<inf>O</inf> defects is highest at a reduction temperature of ∼550 °C and slightly decreases after that. To confirm the formation of V<inf>O</inf> defects, first-principles calculations were independently carried out using a 126-atom K<inf>2</inf>Ti<inf>6</inf>O<inf>13</inf> supercell with V<inf>O</inf> at various positions. Based on calculated EXAFS, the removal of the oxygen atom nearest to the tunnel, which is the lowest energy structure, provides a good match to the experimental spectra.
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Processing development and properties of cobalt-chromium alloys fabricated by traditional method
(2018-01-01)
Vittayakorn, Wanwilai
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Poolphol, Phieraya
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Aimprakod, Kantapon
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Maluangnont, Tosapol
In this work, the cobalt-chromium (Co-Cr) alloy was fabricated via conventional powder metallurgy method followed by sintering in an argon atmosphere. The Co-Cr pellets were formed by uniaxial pressing combined with cold isostatic pressing, aiming for high packing density. Microstructure, chemical compositions and surface morphologies of all samples were investigated via scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX) and atomic force microscopy (AFM), respectively. The biocompatibility of the Co-Cr alloys was investigated by immersing in simulated body fluid (SBF) for different times. The releasing ions were then examined by atomic absorption spectrophotometry (AAS). All the results point out that all properties strongly depend on microstructure and densification of these alloys. Furthermore, the appropriated condition for thermal treatment is performed to Co-Cr alloys in order to study the effect of thermal treatment on related properties. After thermal treatment process at 1200°C for 2 hours, it is found that the amount of pores in samples decreases due to thermal grain growth. For the biocompatibility, the results show that Co amount increases with increasing immersed days whereas Cr amount decreases. For thermal-treated samples, Co and Cr amounts are released to SBF higher than non-thermal-treated samples. The thermal treatment process allows Co-Cr alloys to have higher ductility and lower hardness, releasing a higher concentration of metal ions
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Extending the basic function of lattice oxygen in lepidocrocite titanate – The conversion of intercalated fatty acid to liquid hydrocarbon fuels
(2017-12-01)
Maluangnont, Tosapol
;
Arsa, Pornanan
;
Sooknoi, Tawan
We report herein the basicity of the external and internal lattice oxygen (O<inf>L</inf>) in lepidocrocite titanates with respect to CO<inf>2</inf> and palmitic acid, respectively. Several compositions have been tested with different types of the metal M aliovalently (co)substituted for Ti, K<inf>0.8</inf>[M<inf>y</inf>Ti<inf>2−y</inf>]O<inf>4</inf> (M = Li, Mg, Fe, Co, Ni, Cu, Zn, Cu/Ni and Cu/Zn). The low CO<inf>2</inf> desorption peak temperature (70–100 °C) suggests that the external O<inf>L</inf> sites are weakly basic similar to TiO<inf>2</inf>. However, the internal O<inf>L</inf> sites are sufficiently basic to deprotonate palmitic acid, forming the intercalated potassium palmitate at the interlayer spaces. The latter serves as a two-dimensional (2D) molecular reactor for the production of liquid hydrocarbon fuels via deoxygenation under atmospheric N<inf>2</inf>. A relationship has been observed between the yield of the liquid products vs the partial charge of the lattice oxygen (δ<inf>O</inf>). Since the deoxygenation pathway is highly dependent on the metal substitution, the redox-active sites might also play some roles. The co-substituted K<inf>0.8</inf>[Cu<inf>0.2</inf>Ni<inf>0.2</inf>]Ti<inf>1.6</inf>O<inf>4</inf> produced ~68.0% yield of the liquid products, with ~ 51% saturated and ~ 15% unsaturated C<inf>15</inf> hydrocarbons at 350 °C.
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Synthesis of BaTiO3@TiO2-sheet Core-Shell Structured Nanocomposites
(2019-01-02)
Nawanil, Chanisa
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Panprom, Parinya
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Makcharoen, Worawut
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Khaosa-Ard, Krittanat
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Maluangnont, Tosapol
Core-shell structure nanocomposites have been of interest, as they can exhibit unique properties arising from the combination of peculiar characteristics of each component. In this research, core-shell structured nanocomposites, comprising barium titanate (BaTiO<inf>3</inf>; BT) nanoparticles as the core and titanate (TiO<inf>2</inf>) nanosheets as the shell, were prepared. The surface of barium titanate (BT) nanoparticles was modified chemically by hydrogen peroxide (H<inf>2</inf>O<inf>2</inf>) to create hydroxyl groups. TiO<inf>2</inf> nanosheets were deposited on the surface of the functionalized BT core, via alternate adsorption with oppositely charged polyelectrolyte poly(diallyl dimethylammonium) (PDDA) cations to produce an ultrathin TiO<inf>2</inf> shell layer that encapsulates BaTiO<inf>3</inf> nanoparticles. The structure of the core-shell particles was investigated in order to illustrate their formation mechanisms. Furthermore, this work reported the advance in utilizing a core-shell nanostructure to enhance relative permittivity and maintaining a low loss of polymer nanocomposites. A significant improvement in relative permittivity is attributed to the TiO<inf>2</inf> shell, which acts as polarizable dipoles and consequently enhances interfacial polarization. The results indicated that the structure of core-shell nanocomposites is attractive as a novel structural building block for fabricating novel materials and electronic devices.

Maluangnont, Tosapol

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