Papers by Author: Kamonpan Pengpat

Abstract: Recent years, propolis has plenty of biological and pharmacological properties and its mechanisms of action have been widely investigated. There is a substantive database on the biological activity and toxicity of propolis indicating it may have many antibiotic, antifungal, antiviral and antitumor properties, among other attributes. The one-step incorporation of propolis into nanofibrous mats of polycaprolactone (PCL) by electrospinning was demonstrated. In this research, the preparation of the PCL nanofibers films added ethanolic extract propolis (EEP) by electrospinning technique was studied. The EEP content was varied from 0, 2, 4, 6, 8 and 10%. The morphology was observed by a scanning electron microscope (SEM). The functional group was investigated by FT-IR

Abstract: In this research, the two-step sintering method was employed to develop the physical properties of Hydroxyapatite (HA) ceramics. HA powder was extracted from bovine bone and vibro-milling method was used to make the fine particles. For the two-step sintering process, the samples were heated up to the first step temperature (T₁=1200^°C) for 6 min then the temperature was lowered down to second step temperatures (T₂=1150^°C and 1100^°C) for 5, 10 and 15 h. Another set of samples were heated up to the first step temperature (T₁=1250^°C) for 6 min then the temperature was lowered down to second step temperature (T₂=1150^°C) for 5, 10 and 15 h. X-ray diffraction (XRD) was carried out for investigating the phase formation in the prepared ceramics. Physical properties of the prepared ceramics were studied such as porosity, density by Archimedess principle. It is found that most of the samples exhibit Ca₅(PO₄)₃(OH) phase with JCPDS number 09-0432. The first step temperature plays the most roles on controlling the density of HA ceramics than T₂ and dwell times. Microstructures of the HA powder and ceramics were characterized using scanning electron microscope (SEM).The feasibility in using the prepared ceramics for bone replacement applications was discussed.

Abstract: Hydroxyapatite (HA) is classified as one of the important bioceramics, which has been used in orthopedics, medical and dental applications. It has bioactivity and good biocompatibility with the human organism, which is suitable in medical applications as an implant or coating on prostheses such as metal. In this study, the effects of calcinations temperatures on phase formation and physical properties of HA particles were investigated. The HA particles synthesized from bovine bone were cleaned and fired at 800°C and subsequently ball milled for 24 h. Then received HA particles were divided into two parts. The first one was calcined at various temperatures from 900 to 1400°C and the second one was vibratory milled for 4 h and subsequently calcined at various temperatures from 900 to 1400°C. The calcined HA particles were characterized by X-ray diffraction (XRD) for their crystal structure and particle size analysis. Scanning electron microscope (SEM) was used for microstructural.

Abstract: The aim of this study was to investigate the effect of BaZr_0.05Ti_0.95O₃ (BZT) addition on the microstructure, physical, dielectric and piezoelectric properties of hydroxyapatite (HA), and develop new biomaterials which have potential applications in the support for cellular growth and in the system for bone regeneration. In this case the BaZr_0.05Ti_0.95O₃- HA composites (HABZT) were prepared by conventional sintering method. The BZT were added to HA with ratio 0, 10, 20 and 30 %wt. Then the mixed powders were pressed and subsequently sintered at the temperature ranging from 1150 to 1350°C. The result showed that the dielectric and piezoelectric properties were improved by the addition of BZT. Moreover, the bioactivity of the HA improved with addition of BZT especially at 10% as evident by the formation of bone like apatite layers on the surface of all BCZT composites after soaking in simulated body fluid (SBF) for 15 days. The results confirmed the possibility of using these bioactive composites for treatment within the human body.

Abstract: American foulbrood, European foulbrood, Chalkbrood diseases and the varroa mite are all serious problems for beekeepers. These problem have led to the death of bee larvae and adults and ultimately in many cases severe economic loss. The most common method to treat these problems is through chemical treatments, however, such treatments are not generally acceptable due to the harmful chemical residues for the consumers. Here we pursue an alternative approach using essential oils studied in vitro. Lemon grass oil has been found to be the most effective agent against some microbial diseases and the parasitic mite. In this study we pursue an effective means to deliver the volatile oils by using porous ceramic materials as supporting media. In field trials, we used porous ceramics prepared using diatomaceous earth and activated charcoal as the main starting materials. The amount of activated charcoal was varied at 10, 20, 25, and 42.1 g. to determine optimal adsorption and control emission of the volatile lemongrass oil.

Abstract: Effects of carboxymethyl cellulose from papaya peel (CMCp) on the properties of ceramics were investigated. Cellulose was extracted from papaya peels by NaOH and then it was modified by chloro acetic acid to obtain carboxymethyl cellulose. The prepared CMCp was applied as a binder in ceramic slip in order to increase its viscosity. Sodium silicate was also added into the slip for providing a dispersion of slip and protecting the sedimentation of clay particles. Various concentrations of CMCp and commercial CMC (CMCc) (0.05, 0.1, 0.15, 0.2 and 0.25% w/w of dry weight of clays) were added into the slip. Effect of CMC on viscosity of the slip and the ceramic density were studied. The relationship between the ceramic properties such as, shrinkage, porosity, casting rate and bending strength (both green strength and fired strength), and CMC concentration was also observed. As increasing both CMCp and CMCc, viscosity increased while density decreased. The prepared ceramics (green ware and fired ware) added with CMCp were found to have higher strength and lower in %shrinkage than that of adding with CMCc. The thickness of the ceramic wall adding CMCc increased with increasing CMCc concentration, and time in contrast to that of CMCp as the thickness decreased with increasing CMCp concentration. However, the ceramics with addition of CMCp possessed higher strength than that of the commercial one.

Abstract: In this study, barium stannate titanate ceramics with an addition of boron oxide were synthesized via a solid-state sintering method. The effect of sintering aid on electrical and mechanical properties of barium stannate titanate ceramics was investigated. It was found that, the ceramic with 2 wt% boron oxide showed the lowest porosity and the highest dielectric constant of ~ 13700 at room temperature. In addition, an increase in the boron oxide content was observed to enhance the hardness of the ceramics. These results may be helpful in the multilayer capacitor applications.

Abstract: In this work, preparation conditions and effect of ZrO2 doped BaFe0.5Nb0.5O3 ceramics were studied. Relationship between structure and dielectric properties was investigated. Single-phase cubic BFN powder was synthesized by solid-state reaction at 1200°C for 4 hours with heating and cooling rate of 5°C/min. Various amount of ZrO2 doped from 0.1 to 0.5 %weight were used for doping. After that BFN ceramics were formed via uniaxial pressing and sintered at 1300°C for 4 hours with heating and cooling rate of 5°C/min. Physical properties, microstructure, phase evolution and dielectric properties were studied to find out the optimum conditions for high voltage capacitor applications.

Abstract: BaFe0.5Nb0.5O3 (BFN) exhibits very high dielectric constant over a wide temperature range. However, these materials normally require high-temperature sintering to achieve a maximum densification. The aim of this study is to determine the effect of potassium fluoride salt on the sintering and dielectric properties of BFN ceramics. The results show that KF additive lower the sintering temperature by 100-200°C without affecting the formation of BFN phase. Ceramics doped with 1% KF show optimum densities of about 95% of the theoretical value when sintered at 1300°C. The addition of fluoride salt in the BFN ceramics causes very broad dielectric constant curves over a wide temperature range indicating the diffuse phase transition characteristic. Furthermore, this addition also reduces in the dielectric loss when compared with pure BFN ceramics