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Dive into the research topics where Phakkhananan Pakawanit is active.

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Featured researches published by Phakkhananan Pakawanit.


Materials Science and Engineering: C | 2016

Synthesis and cytotoxicity study of magnesium ferrite-gold core-shell nanoparticles

Jeeranan Nonkumwong; Phakkhananan Pakawanit; Angkana Wipatanawin; Pongsakorn Jantaratana; Supon Ananta; Laongnuan Srisombat

In this work, the core-magnesium ferrite (MgFe2O4) nanoparticles were prepared by hydrothermal technique. Completed gold (Au) shell coating on the surfaces of MgFe2O4 nanoparticles was obtained by varying core/shell ratios via a reduction method. Phase identification, morphological evolution, optical properties, magnetic properties and cytotoxicity to mammalian cells of these MgFe2O4 core coated with Au nanoparticles were examined by using a combination of X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy, UV-visible spectroscopy (UV-vis), vibrating sample magnetometry and resazurin microplate assay techniques. In general, TEM images revealed different sizes of the core-shell nanoparticles generated from various core/shell ratios and confirmed the completed Au shell coating on MgFe2O4 core nanoparticles via suitable core/shell ratio with particle size less than 100 nm. The core-shell nanoparticle size and the quality of coating influence the optical properties of the products. The UV-vis spectra of complete coated MgFe2O4-Au core-shell nanoparticles exhibit the absorption bands in the near-Infrared (NIR) region indicating high potential for therapeutic applications. Based on the magnetic property measurement, it was found that the obtained MgFe2O4-Au core-shell nanoparticles still exhibit superparamagnetism with lower saturation magnetization value, compared with MgFe2O4 core. Both of MgFe2O4 and MgFe2O4-Au core-shell also showed in vitro non-cytotoxicity to mouse areola fibroblast (L-929) cell line.


Advanced Materials Research | 2011

Influence of sintering temperature on densification and microstructure of Zn3Nb2O8 ceramics derived from nanopowders

Phakkhananan Pakawanit; Supon Ananta

Zinc niobate, Zn3Nb2O8, dielectric ceramics were fabricated by sintering Zn3Nb2O8 nanopowders derived from a rapid vibro-milling technique at various temperatures. Phase formation, densification, microstructure and dielectric properties of the ceramics were investigated as a function of sintering temperatures (1000-1200°C), using a combination of X-ray diffraction, Archimedes density measurement, scanning electron microscopy and dielectric measurement, respectively. It has been found that single-phase Zn3Nb2O8 ceramics with maximum density of ~98% theoretical density can be successfully produced with appropriate firing temperature, without any firing additives. Moreover, it is seen that the dielectric properties are found to enhance with increasing sintering temperature and grain size.


RSC Advances | 2014

A strategy to design biocompatible polymer particles possessing increased loading efficiency and controlled-release properties

Phakkhananan Pakawanit; Supon Ananta; Tae Kwan Yun; Jae Young Bae; Wongi Jang; Hongsik Byun; Jun-Hyun Kim

Temperature-responsive poly(N-isopropylacrylamide), or poly(NIPAM), layers were reliably prepared around guest molecule (i.e., rhodamine B)-loaded mesoporous silica (SiO2) particles via thermally- and light-induced radical polymerizations. Subsequent removal of the sacrificial SiO2 particles with dilute hydrofluoric acid led to the formation of biocompatible polymer particles possessing a high dose of rhodamine B. The use of SiO2 core templates not only led to the formation of a uniform coating of the poly(NIPAM) layers, but also increased the stability of the guest molecule, rhodamine B, throughout polymerization. Interestingly, the light-induced radical polymerization method resulted in much less inevitable leaching and decomposition of azo-based guest molecules. The structural information and overall dye-loading efficiency of the mesoporous particles and the final polymer particles were then thoroughly examined by electron microscopes, dynamic light scattering, and fluorescence spectroscopy. As poly(NIPAM)-based particles exhibited significant swelling and deswelling properties above and below the lower critical solution temperature, the controlled-release properties of the poly(NIPAM) particles prepared by both methods were also evaluated. Generally, the dye-loaded poly(NIPAM) particles prepared by the light-induced approach resulted in a thinner coating of the polymer layers and exhibited much higher loading and tunable release profiles of the loaded guest molecules than those prepared by the thermally-induced polymerization. Given these features, the generalization of our strategy to design chemotherapeutically interesting drug-loaded polymer particles that are biocompatible and sensitive to external stimuli will allow for the further development of novel biomedical delivery and treatment systems.


Journal of Applied Physics | 2013

Probing local structure of pyrochlore lead zinc niobate with synchrotron x-ray absorption spectroscopy technique

Kanokwan Kanchiang; Sittichain Pramchu; Rattikorn Yimnirun; Phakkhananan Pakawanit; Supon Ananta; Yongyut Laosiritaworn

Local structure of lead zinc niobate (PZN) ceramic, synthesized via B-site oxide precursor route in atmospheric pressure, was investigated using synchrotron x-ray absorption spectroscopy (XAS) technique. The x-ray absorption near-edge structure (XANES) simulation was first carried out. The XANES simulation results indicate that the PZN ceramic is in pyrochlore phase having Zn2+ substituted on Nb5+ site. Afterwards, the extended x-ray absorption fine structure (EXAFS) analysis was performed to extract the bond length information between Zn2+ and its neighboring atoms. From the EXAFS fitting, the bond length between Zn2+ and Pb2+ in the pyrochlore phase was found to be longer than the previously reported bond length in the perovskite phase. Further, with the radial distribution information of Zn2+s neighboring atoms, the formation energies along the precursor-to-pyrochlore and precursor-to-perovskite reaction paths were calculated using the density functional theory (DFT). The calculated results show that ...


Integrated Ferroelectrics | 2013

Effect of Two-Stage Reaction Sintering Technique on Phase Formation, Microstructure and Dielectric Properties of 0.93Pb(Zn1/3Nb2/3)O3–0.07BaTiO3 Ceramics

Phakkhananan Pakawanit; Athipong Ngamjarurojana; Anurak Prasatkhetragarn; Supon Ananta

Influences of a combination between the two-stage sintering and the reaction sintering techniques on phase formation, microstructure and dielectric properties of relaxor perovskite 0.93Pb(Zn1/3Nb2/3)O3–0.07BaTiO3 or 0.93PZN-0.07BT ceramics were determined via X-ray diffraction, scanning electron microscopy and dielectric measurement techniques, respectively. Under suitable two-stage reaction sintering schemes, it was found that dense and pure perovskite 0.93PZN-0.07BT ceramics with fine grain size can be successfully achieved with better dielectric properties than those of ceramics from single-stage reaction sintering.


Nanotechnology | 2017

Ag/Au/Pt trimetallic nanoparticles with defects: preparation, characterization, and electrocatalytic activity in methanol oxidation

Kontee Thongthai; Phakkhananan Pakawanit; Narong Chanlek; Jun-Hyun Kim; Supon Ananta; Laongnuan Srisombat

Two series of Ag x /Au/Pt y trimetallic nanoparticles (Ag x Au1Pt2 with x ranging from 1-5 and Ag4Au1Pt y with y ranging from 1-3) were prepared by a sequential chemical reduction method that involved the deposition of Pt on preformed Ag/Au core-shell particles by systematically controlling the amount of Ag, Au, and Pt metal precursor solutions. The structural changes (the diameters and increased surface roughness from the defective features) and absorption patterns (the significant reduction of the peak intensities) of the nanoparticles examined with TEM and UV-vis spectroscopy indicated the selective incorporation of Pt on the Ag/Au nanoparticles regardless of their compositions. In addition, a combination of WDX, XRD, and XPS analyses quantitatively and qualitatively confirmed the successful formation of the Ag x Au1Pt2 and Ag4Au1Pt y trimetallic nanoparticles. Subsequently, these series of nanoparticles were deposited on multi-wall carbon nanotubes (MWCNTs) to evaluate their electrocatalytic property in the methanol oxidation reaction (MOR) as a function of their metal compositions. The results showed that the electrocatalytic activities of all Ag4/Au1/Pt y systems were higher than those of typical Pt on the MWCNTs. In particular, the Ag4Au1Pt2 nanoparticles exhibited the highest electrocatalytic property for the MOR, suggesting the importance of the proper combination of metal constituents and structures to regulate the activity in electrocatalytic systems.


Ferroelectrics | 2013

Comparative Studies of Mixed-oxide Synthetic Routes for the Production of Ferroelectric PZN-based Ceramics

Phakkhananan Pakawanit; Athipong Ngamjarurojana; Anurak Prasatkhetragarn; Supon Ananta

In this work, comparative studies of three different mixed-oxide synthetic routes i.e. the conventional, the B-site precursor and the combination of B-site precursor and perovskite phase stabilizer on phase formation, microstructure and dielectric properties of ferroelectric lead zinc niobate-based ceramics were demonstrated via a combination of X-ray diffraction, scanning electron microscopy and dielectric measurement techniques. It was found that dense, pure perovskite ceramics with homogenous microstructure and better dielectric properties can be obtained via the B-site precursor technique.


Advanced Materials Research | 2011

Synthesis and Characterization of Pyrochlore Lead Zinc Niobate Nanopowders Derived from Zn3Nb2O8 Precursor

Phakkhananan Pakawanit; Supon Ananta

A novel approach to synthesis cubic pyrochlore lead zinc niobate-based Pb1.88Zn0.3Nb1.25O5.305 nanopowders with a modified mixed-oxide method has been developed. To ensure a pure phase pyrochlore formation, an intermediate phase of Zn3Nb2O8 was employed as key precursor. The formation of pyrochlore phase in the calcined lead zinc niobate powders has been examined as a function of firing temperature by a combination of TG-DTA and XRD techniques. The morphology evolution has been examined by SEM technique. It has been found that the unreacted PbO and Zn3Nb2O8 phases tend to form together with lead zinc niobate, with the latter appearing in cubic phase. It is seen that optimization of firing temperature can lead to a single-phase Pb1.88Zn0.3Nb1.25O5.305 powders with average particle sizes ranging from 75-400 nm.


Nanotechnology | 2017

Polymer particles filled with multiple colloidal silica via in situ sol-gel process and their thermal property

Hongsik Byun; Jiayun Hu; Phakkhananan Pakawanit; Laongnuan Srisombat; Jun-Hyun Kim

The in situ formation of dielectric silica (SiO2) particles was carried out in the presence of temperature-responsive poly(N-isopropylacrylamide) particles. Unlike the typical sol-gel method used to prepare various SiO2 particles, the highly uniform growth of SiO2 particles was achieved within the cross-linked polymer particles (i.e., the polymer particles were filled with the SiO2 particles) simply by utilizing interfacial interactions, including the van der Waals attractive force and hydrogen bonding in nanoscale environments. The structural and morphological features as well as the thermal behaviors of these composites were thoroughly examined by electron microscopes, dynamic light scattering, and thermal analyzers. In particular, the thermal properties of these composites were completely different from the bare polymer, SiO2 particles, and their mixtures, which clearly suggested the successful incorporation of multiple SiO2 particles within the cross-linked polymer particles. Similarly, titanium oxide (TiO2) particles were easily embedded within the polymer particle template which exhibited improved overall properties. As a whole, understanding in situ formation of nanoscale inorganic particles within polymer particle templates can allow for designing novel composite materials possessing enhanced chemical and physical properties.


Ferroelectrics | 2017

Effect of gold nanoparticles on lead zinc niobate–barium titanate structure by X-ray absorption spectroscopy

Phakkhananan Pakawanit; Rattikorn Yimnirun; Yongyut Laosiritaworn; Kanokwan Kanchiang

ABSTRACT The 0.93PZN-0.07BT ceramics containing 0.5 wt% AuNPs sintering was carried out for 3 – 5 h at various temperatures ranging from 1100 to 1150°C. The effect of AuNPs on 0.93PZN-0.07BT local structure and dielectric properties were investigated. The Au K-edge XANES spectrum indicated that AuNPs are not substituted into 0.93PZN-0.07BT structure. The dielectric constants and dielectric loss of 0.93PZN-0.07BT ceramics containing 0.5 wt% AuNPs after sintering at 1050°C for 3–5 h are higher and lower than that of 0.93PZN-0.07BT ceramics without AuNPs after sintering at 1100°C for 3–5 h, respectively, which can be described by assuming the connectivity series between the ceramics and the metal phases. In addition, Curie temperature shifting of 0.93PZN-0.07BT ceramics containing 0.5 wt% AuNPs due to the higher degree of chemical heterogeneity caused by the AuNPs addition. Therefore, the including of AuNPs into 0.93PZN-0.07BT ceramics can be improving dielectric properties with lower temperature and shorter time in sintering process.

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Rattikorn Yimnirun

Suranaree University of Technology

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Jun-Hyun Kim

Illinois State University

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