Pisutti Dararutana

Ultrastructural Characterization of Liposomes Using Transmission Electron Microscope

A liposome is a spherical vesicle composed of phospholipids and cholesterol bilayer membrane and contains a core of aqueous solution. Liposomes are polymeric nanoparticles used for drug delivery due to their unique properties. It can carry both hydrophobic and hydrophilic molecules. In this study, we showed the benefit of using transmission electron microscope (TEM) with negative staining technique to investigate the morphology of liposomes produced by thin film method. At the same magnification of micrograph results, we could see the multilamellar vesicles of liposomes in various figures and different sizes.

Raman spectroscopic study on archaeological glasses in Thailand: Ancient Thai Glass

Glasses have been used as ornamental and decorative objects in Thailand for several hundred years as seen in archaeological artifacts, such as glass beads found throughout the regions. Decorative glasses can generally be seen as architectural components in Buddhist temples and old-styled palaces. They came in various colors ranging from transparent to amber, blue, green and red of different shades and tones. Fragments of archaeological glass samples were characterized for the first time using Raman spectrophotometer with the aim of obtaining information that would lead to the identification of the glass samples by means of laser scattering. The samples were also investigated using other techniques, such as proton induced X-ray emission spectroscopy, scanning electron microscopy cooperated with energy dispersive X-ray fluorescence spectrometer and synchrotron radiation to induced X-ray fluorescence. The results showed that they were mostly lead-silica based glasses whose colors were induced by metal ions. The differences in chemical compositions were confirmed by Raman signature spectra.

Raman spectroscopic investigation on high refractive index glasses prepared from local quartz sand

High refractive index (RI) glasses prepared from local quartz sand and compounds of heavy elements, such as, barium carbonate, lead oxide, and bismuth oxide as major ingredients were investigated using Raman spectroscopy. The results showed changes in glass structures of different doping elements, namely, Ba, Pb, and Bi. Refractive indices, densities, and UV-vis-NIR spectra of the glass samples were also measured. The Raman spectroscopy can be used to investigate and/or identify heavy glasses, local ancient glasses as well as glass jewelry.

Lead-Free High Refractive Index Glasses Produced from Local Raw Materials

Many difference useful and decorative articles have been made from glasses over the centuries, especially lead-containing glasses. Due to harmful effects of lead from glass fabrication process on human beings and considering the health as well as the environmental issues, many researchers tried to produce leadless glasses using some heavy chemical elements such as barium, bismuth and zirconium. Nowadays, barium compounds seemed to be satisfactory and to be able to increase the refractive index. For production of high quality crystal glasses with high refractive index in Thailand, most raw materials including high quality sand have been imported. Because, Thailand, in fact, is rich in many kinds of raw materials for glass manufacturing, therefore, this work is set up to study the fabrication of the lead-free high refractive index glasses using local sand and barite as the main raw materials. After complete melting, the physical and optical properties of the prepared glass samples were determined to compare these properties with those of glasses prepared from foreign sand. It was found that the prepared glasses produced from local raw materials were suitably for restoration, decoration, radiation shielding, as well as glass jewelry. These glasses can be considered as one of the environmental friendly materials.

Effects of Gold Nanoparticles on the Fabrication of Red Colored High Refractive Index Lead Glass

Red colored gold ruby glass used for decorations in ancient times was actually gold nanotechnology at work by the addition of gold particles into molten lead glass. Most of high refractive index glasses are based on lead-bearing silicate glass. High refractive index lead glasses (HRLG) made from local sands and lead oxide were successfully fabricated both in laboratory and larger scales. In this study, gold metal was doped into the lead glass mixtures. Morphology of the prepared lead glass was observed using SEM and compared with that of the red colored Ancient Thai Glass (ATG). It was found that the fabricated red colored HRLG yielded similar color and clarity to the red colored ATG. From electron micrographs, the presence of gold in lead glass was in the form of nanoparticles. The optical properties of the glasses were also examined.

Characterization of prehistorical glass beads excavated from Khao Sam Kaeo (Chumphon, Thailand) using PIXE and SEM–EDS

It was proved that non-destructive and non-sampling methods were used to analyze the composition of the archaeological glasses. Glass has been used in ornaments and decoration in Thailand for thousands of years. In this study, glass bead fragments found from the archaeological site at Khao Sam Kaeo, Chumphon Province, southern Thailand were analyzed by the proton induced X-ray emission spectroscopy (PIXE) and scanning electron microscope coupled with energy dispersive X-ray fluorescence spectroscopy (SEM–EDS). The composition analysis showed that copper was mainly presence as the colorant. Titanium, common impurity in sand, was all present in the glass bead samples. Furthermore, this type of glass almost spread over the various sites in this region that demonstrated the long distance or exchange connections. Finally, PIXE and SEM–EDS have been used to be the efficient techniques to analyze the archaeological objects, especially the glassy materials, to understand their characteristics and how they were produced in ancient times.

X-ray absorption near-edge structure of chromium ions in α-Al2O3

Both synthetic and natural α-Al2O3 samples with different Cr concentrations were investigated by XANES. The Cr contents were analyzed using LA-ICP-MS technique prior to this experiment. XANES spectra combined with first principle calculations showed the transformation from α-Al2O3:Cr3+ to α-Al2O3:Cr3+,Cr3+ or α-Cr2O3 as the Cr-Cr content increased. The absorption transformation could be resulted from the change of environment around Cr3+ ions, i.e., the Al-O-Cr bonds decreased while the Cr-O-Cr bonds increased. Significant differences in XANES line shapes observed for synthetic and natural α-Al2O3 samples suggested the differences in local environments around Cr ions in both samples. The XANES line shape of α-Al2O3:Cr3+,Cr3+ or Cr ion pairs corresponded to the Cr content, which was also confirmed by the intensity ratios between N2-line and sideband S of R-lines of photoluminescence spectra.

Defect-Induced Properties of Doped Alpha Alumina Samples

The dielectric constant values of a set of synthetic alpha alumina samples doped with Cr and Be were determined using parallel plate method. The voltage frequency was selected at 1 MHz. When Cr was doped to the sample, the dielectric constant was increased due to the increase in polarizations of the sample, whereas the Be-doped one showed the decrease in dielectric constant cf. the undoped synthetic alpha alumina (reference sample). Experiments on doping alpha alumina with both elements showed increasing in dielectric constant compared to the undoped reference sample, i.e., Cr has more influence to the dielectric constant value. Dielectric constants of a set of natural sapphires were also measured and compared to those obtained from the synthetic ones. The results of both natural and synthetic samples varied in the same direction. It suggests, however, that the geological origins of the samples are needed to be considered. This is due to the differences in physico-chemical conditions of their formations that would have influenced partitioning of trace elements as well as evolving of defects in natural samples. Increasing of the R1 and R2 photoluminescence wavelengths and decreasing of refractive indices of the doped samples cf. those of the reference sample were obtained from the experiments.

Study of Metal Coating on Lead-Free High Refractive Index Glass Prepared from Local Sand

Lead-containing glasses coated with lead metal have been used for decoration in Thailand for a long time, were a high refractive index glass. Due to harmful effects of lead, time degradation of glass and because of many kinds of local raw materials for glass production especially sand, colorless lead-free high refractive index glasses were prepared by using local raw materials. In this work, the various kinds of metals; silver and aluminum, were coated on the surface of the prepared glasses using both chemical and physical methods. The joining interfacial layer between the glass body and the coated layer was studied using a scanning electron microscope and the hardness of the coated glasses was measured by a microhardness tester to compare with those of lead coating. It was found that the structures between the joining interfacial layers were similar. The values of the Knoop hardness were approximately 520±20 kg/mm2. This glass can be used to replace the lead glass for restoration glass or decoration onto the surface of the new wood or the metal carving products.

Nuclear analytical methods on ancient Thai rice

For more than half of humanity, rice is life. Rice is a grain which has shaped the history, culture, diet and economy of billions of people in Asia. In Thailand, it is the essence of life. Archaeological evidence revealed that rice had been planted in northeastern area of Thailand more than 5,500 years ago which is earlier than in China and India. The ancient rice grains were found in various archaeological sites in Thailand such as Nakhon Nayok, Suphan Buri and Prachin Buri Provinces. In this work, the ancient black rice from Nakhon Nayok Province was elementally analyzed using scanning electron microscope coupled with energy dispersive X-ray fluorescence spectroscopy, proton induced X-ray emission spectroscopy and micro-beam energy dispersive X-ray fluorescence spectroscopy. Infrared (IR) spectroscopy was also used to study the chemical composition and bio-molecular structure. The grains were oblique in shape with a rough surface. Three major elements (Si, Ca and Al) and other trace elements were detected. The IR spectra provided some information about the presence of molecular bonds.