Modified Self-Avoiding Walk in a Polymerization Process

Darapond Triampo,I.M. Tang,P. Pongkitiwanichkul,W. Triampo 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.2

The modified SAW (mSAW) is defined as a statistical method to treat a polymerization process in a manner similar to that used to treat chains with excluded volume statistics where no two monomers can occupy the same site in space. Unlike the chains with excluded volume statistics, the walk algorithm does not terminate when the next walk is an occupied site. Instead the walker continues along a different direction. Monte Carlo simulations of the random walk are carried out on both 2D and 3D lattices. Universality classes different from those of the chain with excluded volume statistics are found. The critical exponents of the mean-square end-to-end distance are found to be 1.437 (0.005) for 2D and 1.007 (0.004) for 3D, where the figures in the parentheses are the uncertainties of the last digit. The universality classes are determined from rigorous computer simulations

High School Exploration of a Phase Change Material as a Thermal Energy Storage

Ardnaree, Kwanhathai,Triampo, Darapond,Yodyingyong, Supan Korean Chemical Society 2021 대한화학회지 Vol.65 No.2

The present study describes a hands-on experiment to help students understand the concept of phase change or phase transition and its application in a phase change material (PCM). PCMs are substances that have the capability of storing and releasing large amounts of thermal energy. They act as energy storage materials that provide an effective way to save energy by reducing the electricity required for heating and cooling. Lauric acid (LA) was selected as an example of the PCM. Students investigated the temperature change of LA and the temperature (of air) inside the test tube. The differences in the temperatures of the systems helped students understand how PCMs work. A one-group pretest and posttest design was implemented with 34 grade-11 students in science and mathematics. Students' understanding was assessed using a multiple-choice test and a questionnaire. The findings revealed that the designed activity helped students understand the concept of phase change and its application to materials for thermal energy storage.

Effect of acid during synthesis on the agglomerated strength of TiO2 nanoparticles

Sarayut Termnak,Wannapong Triampo,Darapond Triampo 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.4

Titanium dioxide (TiO2 or titania) photocatalyst nanoparticle (NPs) powders were prepared. The synthesis steps were performed at room temperature. Based on X-ray diffraction evidence, it was found that only the anatase structure was formed when hydrochloric acid was added during the synthesis. With no acid, both anatase and brookite structures were formed. Transmission electron microscopy (TEM) showed that the primary particles from both the acid and no-acid routes were of approximately the same size. A particle-size analyzer equipped with an ultrasonic generator showed, however, that the aggregates of acid NPs were more difficult to break apart than those of the no-acid NPs. Gel formation was used to explain the difference in strength by which the NPs aggregated. Titanium dioxide (TiO2 or titania) photocatalyst nanoparticle (NPs) powders were prepared. The synthesis steps were performed at room temperature. Based on X-ray diffraction evidence, it was found that only the anatase structure was formed when hydrochloric acid was added during the synthesis. With no acid, both anatase and brookite structures were formed. Transmission electron microscopy (TEM) showed that the primary particles from both the acid and no-acid routes were of approximately the same size. A particle-size analyzer equipped with an ultrasonic generator showed, however, that the aggregates of acid NPs were more difficult to break apart than those of the no-acid NPs. Gel formation was used to explain the difference in strength by which the NPs aggregated.

Stochastic Modeling of External Electric Field Effect on Escherichia Coli Min Protein Dynamics

Charin MODCHANG,Wannapong TRIAMPO,Paisan KANTHANG,Udorn JUNTHORN,Somrit UNAI,Waipot NGAMSAAD,Narin NUTTAVUT,Darapond TRIAMPO,Yongwirnon LENBURY 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.2

Cel division in Escherichia coli and other rod-shaped bacteria depends on the precise place- ment of a division septum at the cel center. The MinCDE system consisting of thre proteins, MinC, MinD, and MinE, controls acurate cel division at the center of the cel through pole-to- pole oscilation. With simplifying asumptions and relying on a deterministic model, we present a one-dimensional stochastic model that describes the effects of an external electric field on the MinCDE system. Computer simulations were performed to investigate the response of the oscila- tory dynamics to various strengths of the electric field and to the total number of Min proteins. A sufficient electric field strength was capable of interfering with MinCDE dynamics with posible changes to the cel division proces. Interestingly, effects of an electric field were found not to depend on the total number of Min proteins. The noise involved shifted the corect trend of Min proteins behavior. However, as a consequence of the robustnes of the dynamics, the oscilatory patern of the proteins stil existed even though the number of Min proteins was relatively low. When considering the corelations betwen the local and the global minimum (maximum) of MinD (MinE), the results suggest that using a high enough Min protein concentration wil reduce the localminimum(maximum)effect, which is related to the probability of polar division in each single oscilator cycle. Although this model is simple and neglects some complex mechanisms concerning protein oscilation in corelation with celdivision, it has ben demonstratedto be goodenough for positioning of the dividing site. Nevertheles, more experimental and theoretical studies are neded to provide a more realistic (but of course more complicated) model of bacterial cel division.

Kinetics and mechanism of hydroxyl radical formation studied via electron spin resonance for photocatalytic nanocrystalline titania: Effect of particle size distribution, concentration, and agglomeration

Sasiporn Sroiraya,Wannapong Triampo,Noppawan Phumala Morales,Darapond Triampo 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.2

A photocatalytic process was carried out with two types of TiO₂: commercial (C-TiO₂) and in-house synthesized (S-TiO₂). Parameters, such as, initial particle concentration and the nanoparticle (NPs) agglomerations effect on hydroxyl radical (●OH) concentration were investigated using electron spin resonance (ESR) spectroscopy with a spin trapping technique. The experimental results demonstrate that generation of ●OH and DMPO/●OH (5,5-dimethyl-1-pyrolline-N-oxide/hydroxyl radical) adduct formation is controlled by a shorter time-scale of the chemical reaction on particle surfaces and longer timescale particle agglomerations in the bulk dynamics. It was found that S-TiO₂ has a smaller particle size than C-TiO₂ NPs. As a consequence, S-TiO₂ NPs yield a higher concentration of ●OH compared to that of C-TiO₂NPs of the same concentration. These findings reveal an agreement between the ESR signals, agglomeration size analysis, and transmission electron microscopy (TEM) data. Detail explanations are presented mainly on the drive of dynamic time scales and the limitation of the number of NPs governed by their associated distributions. With the kinetic studies, we propose the mechanism for the generation of ●OH via a study of ESR DMPO/●OH spin trap technique. The mechanism accounts for the active surface area as the agglomeration process occurred throughout the suspension and the possibility of DMPO/●OH recombination as the surface of TiO₂ became dense with DMPO/●OH adduct. A photocatalytic process was carried out with two types of TiO₂: commercial (C-TiO₂) and in-house synthesized (S-TiO₂). Parameters, such as, initial particle concentration and the nanoparticle (NPs) agglomerations effect on hydroxyl radical (●OH) concentration were investigated using electron spin resonance (ESR) spectroscopy with a spin trapping technique. The experimental results demonstrate that generation of ●OH and DMPO/●OH (5,5-dimethyl-1-pyrolline-N-oxide/hydroxyl radical) adduct formation is controlled by a shorter time-scale of the chemical reaction on particle surfaces and longer timescale particle agglomerations in the bulk dynamics. It was found that S-TiO₂ has a smaller particle size than C-TiO₂ NPs. As a consequence, S-TiO₂ NPs yield a higher concentration of ●OH compared to that of C-TiO₂NPs of the same concentration. These findings reveal an agreement between the ESR signals, agglomeration size analysis, and transmission electron microscopy (TEM) data. Detail explanations are presented mainly on the drive of dynamic time scales and the limitation of the number of NPs governed by their associated distributions. With the kinetic studies, we propose the mechanism for the generation of ●OH via a study of ESR DMPO/●OH spin trap technique. The mechanism accounts for the active surface area as the agglomeration process occurred throughout the suspension and the possibility of DMPO/●OH recombination as the surface of TiO₂ became dense with DMPO/●OH adduct.

Agar 그래프트 폴리아크릴산 겔의 흡수능 최적화

Karntarat Wuttisela,Bhinyo Panijpan,Wannapong Triampo,Darapond Triampo 한국고분자학회 2008 폴리머 Vol.32 No.6

Investigating flow patterns in a channel with complex obstacles using the lattice Boltzmann method

Jiraporn Yojina,Waipot Ngamsaad,Narin Nuttavut,Darapond Triampo,Yongwimon Lenbury,Paisan Kanthang,Somchai Sriyab,Wannapong Triampo 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.10

In this work, mesoscopic modeling via a computational lattice Boltzmann method (LBM) is used to investigate the flow pattern phenomena and the physical properties of the flow field around one and two square obstacles inside a two-dimensional channel with a fixed blockage ratio, β =1 4, centered inside a 2D channel, for a range of Reynolds numbers (Re) from 1 to 300. The simulation results show that flow patterns can initially exhibit laminar flow at low Re and then make a transition to periodic, unsteady, and, finally, turbulent flow as the Re get higher. Streamlines and velocity profiles and a vortex shedding pattern are observed. The Strouhal numbers are calculated to characterize the shedding frequency and flow dynamics. The effect of the layouts or configurations of the obstacles are also investigated,and the possible connection between the mixing process and the appropriate design of a chemical mixing system is discussed.

An Ising-like Model for Monolayer-monolayer Coupling in Lipid Bilayers

Kan Sornbundit,Charin MODCHANG,Narin NUTTAVUT,Waipot Ngamsaad,Darapond TRIAMPO,Wannapong TRIAMPO 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.1

We have proposed the Ising bilayer model to study the domain growth dynamics in lipid bilayers. Interactions within and between layers are adopted from recent experimental and theoretical data. We investigate the effects of the mismatch area on the domain coarsening dynamics in both symmetric and asymmetric lipid bilayers. To explore domain coarsening, we used the Monte Carlo (MC) method with a standard Kawasaki dynamics to simulate the systems. The results show that domains on both layers grow following a power-law and that the domains grow slower when the mismatch areas are increased.