Key Engineering Materials Vols. 675-676

Abstract: The Monte Carlo approach is used to calculate carrier mobility in molecular copper phthalocyanine (CuPc) with applied electric field in the range of 0.5 to 20 × 10³ kV/cm. Density functional theory (DFT) is employed to derive the molecular interaction between neighboring molecules with various applied electric fields. The result of DFT calculation to evaluate transfer integral that used to calculate hopping rate in the range of applied electric fields. The charge transfer rate between adjacent molecules can be estimated by using the Marcus–Levich–Jortner (MLJ) formalism. The charge is assumed to be localized on the donor and then transferred to the acceptor. Tunneling is modeled by including selected vibration modes at the quantum mechanical level. The result of hopping rate is in ordered of 10¹⁵ s^-1 for hole hopping in direction of applied electric field on the contrary hopping rate in ordered of 10¹⁴ s^-1. The result of mobility can be calculated in range of 0.44 - 10.0 cm²/Vs decrease as a function of applied electric field that calculated by simple hopping model.

Abstract: In this study, the experimental investigation and assessment the absorption capacity for Zn ion with Amusium Pleuronectes shell. The investigations were carried out by batch method and variables of the batch experiment include solution pH, Contact time, were determind. The mechanism of bisorption is chemisorption or/and physical adsorption was confirmed by X-ray Diffraction (XRD) and Energy Dispersive X-ray Fluorescence (EDXRF). The results showed that the Amusium Pleuronectes shell has a high level of absorption capacity for Zn (II) ions. Another that result of mechanism of biosorption suggests and confirm with the result of XRD and EDXRF.

Abstract: Pectin is a high value functional food ingredient widely used as a gelling agent and stabilizer. The chemical structure of pectin has been the subject of scientific investigations for decades. Coffee producers remove beans; the other source of pectin, from coffee cherries is thrown away. Our study showed that pectin extracted from coffee pulp has high degree of esterification and methoxyl content of 93.75% and 7.87 respectively, which indicated good gelation properties. Nevertheless, here we were interested in the primary structure of pectin which is a complex polysaccharides that contains 1, 4-linked a-D-galactosyluronic acid (GalpA) residue. A theoretical dimension, density functional theory (DFT) with Generalized Gradient Approximation (GGA)/ BLYP functions, was utilized to study methylester substitution in pectin model compounds. For further discussion, the use of a COSMO model in different solvent showed the significant results in the difference torsion angle and HOMO diagram.

Abstract: First principle calculation is performed to investigate structural and electronic properties of strained silicene (silicon analogue of graphene) when absorbing the hydrogen sulfide molecule gas. Two configuration of silicene-H₂S system, center and hollow configuration, is checked under 0% (pure), 5%, and 10% uniaxial engineering strain. We report that the silicene-H₂S system in center configuration has larger binding energy compare to the silicene-H₂S system in hollow configuration. The results show that H₂S is physisorbed on silicene. In this work, we also find the change of band gap energy (~60 meV) is appearing when H₂S interacted with silicene in center configuration, whereas the band gap energy of silicene has no change when interacted with H₂S in hollow configuration.

Abstract: The extractions of yellow and red pigments from safflower petals were studied. The pigment extracted was further utilized as a natural dye for silk dyeing. The safflower petals were water-extracted in order to remove the yellow pigment and the extraction of red pigment from the petals was done with alkali solution. The extracted red pigment was applied to a silk fabric by dyeing process. The effects of dye concentration and pH of dye bath were studied. The colourimetric analysis of each dyed material was done in terms of the CIELab (L*, a* and b*) and K/S values. Maximum color strength for red color was obtained at pH 4. Color fastness to washing and light was evaluated. Washing fastness was 4-5 but light fastness for red dyed silk was 1. The dyed silk did not display antimicrobial activity against the bacteria Staphylococcus aureus ATCC25923^T and Escherichia coli ATCC25922^T.

Abstract: This research studied the isotope effect coefficient of high temperature superconductors. The model used one-band superconductor which considered the competition of superconducting gap and pseudogap in the below crossover temperature region. The isotope effect coefficient is derived and approximation in simplify form. We find that the isotope effect coefficient is decreased as the critical temperature Tc and the crossover temperature T* ratio Tc/T* increased.

Abstract: Peperomia pellucida (Piperaceae) of Thai name “Phak kra sang” is medicinal plant. They are eaten in a salad or as cooked vegetable for protected glaucoma, eye inflammation. Recently, The methanol fraction of P. pellucida was tested for antiamoebic effect. Acanthamoeba spp. are protozoa, free-living in the environment and feed on bacteria. Acanthamoeba spp. are the causative agents of Acanthamoeba keratitis. P. pellucida is medicinal plants, and was interesting for studied antiamobic. The separation by column chromatography (CC) used organic solvent of methanol and ethyl acetate (3:7) gave phytosteryl glycoside (PG). Acanthamoeba spp. was cultured in normal saline and PG is organic compound which was poor soluble in normal saline. This study was developed microemulsion (ME) of PG for effective of antiamoebic activity. Pseudo-ternary phase diagram used for identify ME region. The consisting of ME were dimethyl sulfoxide (DMSO), Tween 20, water and PG. Formulations were prepared with prior mixture of DMSO: Tween20 (co-surfactant: surfactant) in four volume ratio 1:1, 2:1, 3:1 and 4:1 which is each of ratio of Smix. PG was concentrated in 200μg/ml in ethanol. Forming of colloids used Smix in ratios 3:1and 4:1.The stability of ME was ratio was PG: Smix water (1: 9: 4.5). The optimized ME formulation and characterized by zeta potential were found to be 121-397 nm, and conductivity-7.0 mV. Under light microscope ME was absorbed into the endocyst of Acanthamoeb spp., and detected the dead cysts by staining of toluidine blue. IC₅₀ showed 0.88 μg/ml for antiamoebic activity.

Abstract: Sugar is very important raw material of many industries such as food, beverage and renewable energy. In this research, pretreatment and hydrolysis of agricultural wastes to produce reducing sugars for an ethanol production were investigated. The rice stalk and corn stover from agricultural wastes were firstly pretreated with sodium hydroxide at 121 °C in different time as 20 30 and 40 minutes for removal of lignin. After that, the condition of hydrolysis using sulfuric acid of the pretreated rice stalk and corn stover was optimized. The optimum condition that obtained the highest reducing sugar content from rice stalk and corn stover of 76.12 and 136.25 mg/ml were using 1.0 % v/v sulfuric acid at temperature of 121 °C for a hydrolysis time of 40 minutes. This research made value adding in the industrial processing, decrease environmental problem and reduce global warming crisis by optimized utilization of agricultural waste.

Abstract: Structural and electronic properties of CuPc in β structure (β - CuPc) were investigated by first principles calculations. The generalized gradient approximation (GGA) was used to describe the exchange-correlation with the projector-augmented wave (PAW) method. Under ambient pressure, the calculated structural parameters were calculated and found to be in good agreement with other experimental and theoretical values. The calculated direct band gap was found to be 0.683 eV. The results of electronic properties under various pressures were presented. To investigate the properties under pressure, β - CuPc was calculated at several reduced volumes. It was found that the energy gap decreases when the pressure increases. The behaviors of electronic properties under pressure were also discussed.