Titipun Thongtem

Hydrothermal synthesis, characterization, and optical properties of wolframite ZnWO4 nanorods

In this research, the effects of pH, reaction temperature and holding reaction time on the synthesis of one-dimensional ZnWO4 nanostructures by a hydrothermal method were studied. Phase, morphology and atomic vibration were characterized by X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), and Fourier transform infrared (FTIR) and Raman spectroscopy. The pure monoclinic ZnWO4 structure was synthesized at the pH solutions of 7 and 8. By varying the pH values, the mixtures of monoclinic ZnWO4 and hexagonal ZnO as major and minor phases were detected at the pH 9 and 10 solutions, and the pure hexagonal ZnO phase at the pH 11 and 12. SEM and TEM images proved that ZnWO4 nanorods grew along the [021] direction, with the reaction temperature and time to control their morphologies. The Zn–O, Zn–O–W, and W–O stretching vibrations were detected at 474, 888, and 726 cm−1, and their corresponding bending vibrations at 430, 826, and 582 cm−1, respectively. The optical properties of ZnWO4 nanorods were also investigated by UV-visible (UV-vis) and photoluminescence (PL) spectroscopy. The above analyses proved that the appropriate condition for synthesizing of ZnWO4 nanorods is at pH 8 by the 200 °C and 24 h hydrothermal treatment.

Characterization of orthorhombic α-MoO 3 microplates produced by a microwave plasma process

Orthorhombic α-MoO3 microplates were produced from (NH4)6Mo7O24ċ4H2O solid powder by a 900 W microwave plasma for 40, 50, and 60min. Phase, morphologies, and vibration modes were characterized by X-ray diffraction (XRD), selected area electron diffraction (SAED), scanning electron microscopy (SEM), and Raman and Fourier transform infrared (FTIR) spectroscopy. Sixty min processing resulted in the best crystallization of the α-MoO3 phase, with photoluminescence (PL) in a wavelength range of 430-440 nm.

Smart magnetic nanoparticle-aptamer probe for targeted imaging and treatment of hepatocellular carcinoma

We report herein the development of a smart magnetic nanoparticle-aptamer probe, or theranostic nanoprobe, which can be used for targeted imaging and as a drug carrier for hepatocellular carcinoma treatment. The theranostic nanoprobe combines the delivery potential of a non-toxic cellulose derivative polymer, specific capability of cancer-specific molecule (DNA-based EpCAM aptamer) and the imaging capability of magnetic iron oxide nanoparticles. Our proof-of-concept design demonstrates efficient in vitro MR imaging of the cancer cells, and enhanced delivery of an anticancer drug into the cancer cells with comparable treatment efficacy.

Synthesis and Characterization of Europium-Doped Zinc Oxide Photocatalyst

Single crystalline flower-like ZnO and Eu-doped ZnO structures were successfully synthesized via a sonochemical method. Structures, morphologies, and photocatalytic activities of the as-synthesized samples were determined using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and ultraviolet-visible absorption spectroscopy. The photocatalytic activities of the as-synthesized samples were evaluated by the degradation of methylene blue in aqueous solutions under UV light. The photocatalytic results indicate that the as-synthesized Eu-doped ZnO shows good photocatalytic activity and could be considered as a promising photocatalyst for dye waste water treatment.

Synthesis of h- and α-MoO 3 by refluxing and calcination combination: phase and morphology transformation, photocatalysis, and photosensitization

Hexagonal molybdenum oxide (h-MoO3) nano- and microrods were successfully synthesized by refluxing of (NH4)6Mo7O24ċ4H2O solutions with the pH 1 at 90°C for 1, 3, 5, and 7 h and were further transformed into orthorhombic molybdenum oxide (α-MoO3) microplates by calcination at 450°C for 6 h. These selected products were used to determine the degradation of methylene blue dye under 35W xenon lamp for 0-180 min, due to the photocatalysis and photosensitization processes. In this research, catalytic activity of the metastable h-MoO3 has higher efficiency than that of the thermodynamically stable α-MoO3. Their phase and morphology transformation was also explained according to the experimental results.

Characterisation of one-dimensional CdS nanorods synthesised by solvothermal method

One-dimensional (1D) cadmium sulfide nanorods were successfully synthesised using cadmium nitrate and sulfur powder as starting materials and polyvinyl alcohol (PVA, MW = 1 25,000) as a capping agent in ethylenediamine as a solvent by solvothermal method at 200°C for 24 and 72 h. X-ray diffraction patterns (XRD) indicated a single phase of hexagonal wurtzite CdS structure, of which the results are in accordance with those of selected area electron diffraction (SAED). The morphologies of CdS were observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) which showed 1D nanorods. The length and diameter of CdS nanorods were increased when PVA was added and the reaction times were prolonged. High resolution transmission electron microscopy (HRTEM) showed that growth direction of wurtzite CdS nanorods is along [001] direction or c-axis. Raman spectra presented the 1LO and 2LO at 299.36 and 600.72 cm−1, respectively. The 2LO/1LO intensity ratios were increased when the length of CdS nanorods became longer.

Photocatalysis of WO 3 nanoplates synthesized by conventional-hydrothermal and microwave-hydrothermal methods and of commercial WO 3 nanorods

The degradation of methylene blue (MB) dye by tungsten oxide (WO3) photocatalyst synthesized by the 200°C conventional-hydrothermal (C-H) and 270 W microwave-hydrothermal (M-H) methods and commercial WO3 was studied under UV light irradiation for 360 min. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, Raman spectrophotometry, and UV visible spectroscopy to determine phase, morphology, vibration mode, and optical property. The BET analysis revealed the specific surface area of 29.74, 37.25, and 33.56 m2/g for the C-H WO3 nanoplates, M-H WO3 nanoplates, and commercial WO3 nanorods, respectively. In this research, the M-H WO3 nanoplates have the highest photocatalytic efficiency of 90.07% within 360 min, comparing to the C-H WO3 nanoplates and even commercial WO3 nanorods.

Characterization of MnWO4 with flower-like clusters produced using spray pyrolysis

Abstract MnWO 4 (huebnerite) with flower-like clusters of nano-plates was produced from the solutions containing MnCl 2 ·4H 2 O and Na 2 WO 4 ·2H 2 O by the 300 °C spray pyrolysis. The phase was detected by X-ray diffraction (XRD) and selected area electron diffraction (SAED), and is in accordance with the results characterized using energy dispersive X-ray (EDX) analysis. The flower-like clusters of nano-plates were characterized using scanning and transmission electron microscopes (SEM and TEM), and their parallel lattice planes using a high resolution transmission electron microscope (HRTEM). Vibration spectra of the huebnerite structured products were characterized using Raman and Fourier transform infrared (FTIR) spectrometers. Their photoluminescence (PL) emissions are in the same spectral region at 405–412 nm.

Enhanced doxorubicin delivery and cytotoxicity in multidrug resistant cancer cells using multifunctional magnetic nanoparticles

Carboxymethyl modified magnetic nanoparticles (CMC-MNPs) have been designed as a vehicle for drug delivery in both drug-sensitive and drug-resistant cancer cells. We have demonstrated that the CMC-MNPs were able to load doxorubicin (DOX) with a high loading efficiency while also maintaining a good colloidal stability in an aqueous solution. According to a drug release study, DOX-loaded CMC-MNPs showed that the pH-dependent drug release property had a much higher release rate in acidic pH. Compared to free DOX, the DOX-loaded CMC-MNPs showed higher DOX accumulation in drug-sensitive cancer cells and much higher accumulation in drug-resistant cancer cells. These results indicate that our nanoplatform is highly efficient as a drug delivery system in both normal cancer cells and MDR cancer cells. In addition, the DOX-loaded CMC-MNPs can also enhance cytotoxicity against drug-resistant cancer cells in comparison to free DOX. The results obtained in this research demonstrate that our nanoplatform may be a promising approach in cancer chemotherapy and for overcoming multidrug-resistant cancer cells.

High-temperature nitridation of the intermetallic compound TiAl at 1000-1200 K

The nitridation process of MJ12 (Ti-47Al-2Nb-2Cr) and MJ47 (Ti-47Al-2Nb-2Mn + 0.8TiB 2 ) in an atmosphere of purified ammonia has been investigated over the temperature range 1000-1200 K. The nitrided alloys showed improvement of hardness and wear resistance in this environment. At 1200 K nitridation, Knoop hardness values of MJ12 and MJ47 were 1283.6 and 1391.3 kg mm -2 , respectively, and the decrease in wear rate of both alloys was as much as 99%. By using x-ray diffraction, TiN was detected on the surface of the alloys nitrided ≥1100 K.