cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.14457/cu.the.2008.1620
title: Development of packaging film from LDPE/zeolite composites for extending shelf life of fresh produces

description: In this study, LDPE/zeolite composite films were prepared via twin screw extruder attached with blown film set. LDPE and maleic anhydride grafted low density polyethylene (PE-g-MA) was melt blended with zeolite. The effect of PE-g-MA to zeolite ratio, type and content of zeolite on the dispersion of zeolite in composite films was determined. In addition, thermal, mechanical, and gas permeability properties of these composite films were also studied. The chosen composite film was investigated the efficiency on prolonging shelf life and maintaining quality of lime and mango fruits. From SEM results, LDPE/zeolite composite films with PE-g-MA/zeolite ratios of 3.0 and 4.0 showed better dispersion and distribution than those with other ratios. The addition of PE-g-MA into LDPE matrix decreased melting temperature (Tm) and the formation of crystalline phase of LDPE which was confirmed by DSC results. However, the addition of zeolite into LDPE matrix did not affect the formation of crystalline phase. In addition, it was found that LDPE/zeolite composite film at zeolite 5A of 3 phr and PE-g-MA/zeolite ratio of 3.0 exhibited the optimal mechanical and gas permeability properties. The composite film used as packaging prolonged shelf life of mango fruit for 4 weeks while mango fruits inside LDPE packaging film found CO2 injury symptom due to excess CO2 at the third week of storage. For six weeks after storage the chosen composite film delayed green color variation, peduncle drop, and CO2 injury symptom of lime fruits more than neat LDPE film for lime fruits packing for six weeks.
DOI: 10.14457/cu.the.2008.1621
title: Development of solid lipid nanoparticles containing Artocarpus Lakoocha heartwood extract (puag-haad) for whitening and anti-wrinkle effects

description: The main purpose of this study was to develop solid lipid nanoparticles (SLN), an alternative carrier system, for Artocarpus lakoocha heartwood extract (Puag-Haad) to improve Puag-Haad stability and evaluate the whitening and anti-wrinkle efficacies in woman volunteers. At optimum formulations, SLN containing Puag-Haad were successfully developed by w/o/w double emulsion and cold homogenization method using glyceryl monostearate, polyoxyethylene 40 stearate and poloxamer 188 as lipid, surfactant and cosurfactant, respectively. The mean particle sizes and zeta potentials of formulations, when measured by photon correlation spectroscopy (PCS), were 150 – 190 nm for w/o/w double emulsion method and were 250 – 320 nm for cold homogenization method. The particles showed regular, spherical and uniform nanospheres when investigated by transmission electron microscope (TEM). Purification of SLN containing Puag-Haad was achieved by ultrafiltration. Analysis of the amount of oxyresveratrol, a main constituent in Puag-Haad, by high performance liquid chromatography (HPLC) showed high entrapment efficiency of about 85% for w/o/w double emulsion method and 70% for cold homogenization method. In vitro release studies showed sustained release profiles of oxyresveratrol and well fitted the Higuchi equation. After 4 months storage at room temperature and protected from light, the physical and chemical stabilities of SLN containing Puag-Haad (0.25%) were superior to the aqueous solutions of Puag-Haad. The presence of surfactant (polyoxyethylene 40 stearate) and citrate buffer pH 5.5 had additive effect in stabilizing Puag-Haad both physically and chemically. Twenty-six woman volunteers participated in an 8-week study. Each applied the SLN containing Puag-Haad (0.25%) on one of the forearm in comparison with the micellar solution of Puag-Haad on another forearm. The melanin index, skin roughness, skin elasticity and skin hydration were measured every 2 weeks. Repeated measures ANOVA was employed to evaluate the difference in the overall effect between the two formulations over time at the significance level () of 5%. SLN containing Puag-Haad gave significantly better anti-wrinkle, skin elasticity and skin hydration than the micellar solution. On the other hand, the solution showed slightly greater whitening effect than SLN. All the subjects completed the study without developing any unwanted side effects or withdrawal. Therefore, the SLN containing Puag-Haad appeared to have a very promising potential as a novel and effective skin whitening / anti-wrinkle cosmetic delivery system.
DOI: 10.14457/cu.the.2008.1622
title: Distortion-induced stresses in composite steel i-girder bridges

description: Repeated traffic loading assists distortion-induced fatigue cracks in the web gaps at connections between the steel girders and out-of-plane elements such as diaphragms and cross frames in the steel bridges. Unstiffened girder web gaps at the ends of transverse stiffeners, which also serve as diaphragm connection plates, are subjected to high local stresses during cyclic out-of-plane distortion. The out-of-plane distortion was mainly caused by relative girder deflection. This research investigates the effects of bridge parameters on the relative displacement between adjacent girders, vertical web gap stresses, and lateral load distribution factor. The parameters include the girder spacing, slab thickness, girder stiffness, and span length. By using finite element method, dual-level analyses using the global model and submodel were performed. The global model was used to study the relative displacement between adjacent girders and lateral load distribution factor, while the submodel was used for the critical web gap stress. From a parametric study, the rankings of bridge parameters that influence the relative displacement between adjacent girders, web gap stress and lateral load distribution factor are reported. For the web gap stress, the results showed that it is primarily dependent on bridge span length and web gap properties.
DOI: 10.14457/cu.the.2008.1623
title: Effect of asiaticoside on generation of reactive oxygen species by induction of 4-hydroxy-2-nonenal in ECV-304 cells

description: 4-hydroxy-2-nonenal (4-HNE), the most abundant aldehyde product of lipid peroxidation, was shown to exert several effects on pathological processes. Its effects were shown to be tightly associated with an ability to induce intracellular reactive oxygen species (ROS) generation. The purposes of this study were to elucidate the possible cytotoxic role of 4-HNE and underlying mechanisms on ECV-304 cells. Moreover, this study investigated the protective effect of asiaticoside, the major active component of Centella asiatica (Linn.), against 4-HNE mediated cytotoxicity. Exposure with 4-HNE decreased cell viability in a concentration dependent manner over a wide range concentrations (0-40 μM) analyzed by MTT assay. In addition, Hoechst 33342 and propidium iodide staining assay showed a significant increase (P &lt; 0.05) in apoptotic and necrotic cells at 12 hours. Addition of antioxidant, N-acetyl-L-cysteine (NAC) or glutathione (GSH), significantly inhibited (P &lt; 0.05) 4-HNE induced cytotoxicity measured by MTT assay, apoptotic cell death analyzed by Hoechst 33342 staining assay, and necrotic cell death determined by propidium iodide staining assay. Flow cytometric analysis of ROS-specific 2’, 7’ –dichlorodihydrofluorecein diacetate fluorescent dye indicated that 4-HNE treatment strongly significant up-regulated (P &lt; 0.05) intracellular ROS, suggesting the involvement of ROS on 4-HNE induced cytotoxicity. However, asiaticoside which has been reported to be an antioxidant showed antioxidant effect only at high concentrations (200 µM) in this study. These findings provided evidence that antioxidant effect of asiaticoside might not be involved in the protection of ECV-304 cells against 4-HNE induced toxicity. Nevertheless, the precise mechanisms of asiaticoside in protection of 4-HNE induced cytotoxicity remain to be defined.
DOI: 10.14457/cu.the.2008.1624
title: Effect of polymers on gel electrolyte properties in lead acid battery

description: This thesis studied the effects of additives on the performance of gelled-electrolyte by measuring the conductivity values and discharge capacities of valve-regulated lead-acid (VRLA) batteries. The gelled-electrolyte containing 2%(w/v) of fumed silica and 35%(w/v) of sulfuric acid provided the highest conductivity () of 838 mS/cm at 25oC. This gelled electrolyte was selected for development by adding various additives. In order to improve the battery rechargeability, the textural evolution of the positive active material, life cycle and the electrical conductivity of gelled-electrolyte were optimized by using sodium sulfate, orthophosphoric acid, conducting polymers (polyaniline, polypyrrole and poly(1,4-phenylene sulfide)), mixtures of sodium sulfate and orthophosphoric acid, mixtures of sodium sulfate and conducting polymers and mixture of sodium sulfate, orthophosphoric acid and conducting polymers. Moreover, the gelling time and the oxygen recombination process of gelled-electrolytes with various types of additives were investigated. Finally, the discharge capacity was compared with the standard capacity (at 25oC) of VRLA battery containing a liquid electrolyte at a 1-hour rate. From the results, it was found that fumed silica, sulfuric acid and additives affected the electrical conductivity and the gelling time of gelled electrolyte. The conductivity of the gelled electrolytes was related to the discharge capacity of VRLA batteries containing gelled-electrolytes. The high discharge capacities were obtained from gelled electrolytes containing only polypyrrole and a mixture of polypyrrole and sodium sulfate. These electrolytes provided the least water loss. In addition, the gelled electrolytes containing conducting polymers including polyaniline, polypyrrole and poly(1,4-phenylene sulfide) and/or sodium sulfate and without adding additives increased the capacity when compared to the standard VRLA battery containing liquid electrolyte. On the contrary, the gelled electrolytes containing phosphoric acid showed the lowest conductivity and discharge capacity.
DOI: 10.14457/cu.the.2008.1625
title: Effects of calcium carbonate fillers on mechanical properties of flexible polyurethane foam

description: The flexible polyurethane foam was prepared with adding a small amount of calcium carbonate fillers whose average size of 1 m. The content of fillers in polyurethane foam is varied from 0, 3, 5, 7 and 10 %wt of polyol. The isocyanate index was also varied from 90, 100 and 110. The FTIR spectrum of polyurethane composite foams showed the similar peaks in the observed range. It was shown that the content of urethane linkage group decreased with an increase of calcium carbonate content. However, ether groups are increased with the increase of calcium carbonate content. Scanning Electron Microscopy (SEM) was shown the cell structure of the flexible polyurethane that the open cell structure was similar at all isocyanate index. Furthermore, the tensile strength, hardness and density of polyurethane composite foam tended to increase with increase of calcium carbonate filler but the elongation and resilience decreased with increase of the fillers. Although the soft segment was increased with of calcium carbonate filler, the hardness properties of polyurethane foam increased which could be due to the presence of the fillers. In addition, when the isocyanate index in the foam, the hardness properties also increased. In addition, increasing the isocyanate index would increase the intermolecular interaction between filler and matrix thus the tensile strength and hardness of polyurethane foam composites increased but the elongation at break decreased.
DOI: 10.14457/cu.the.2008.1626
title: Effects of Centella Asiatica Extract on Homocysteine-induced injuries in neuronal cell line cultures

description: Asiaticoside, a main triterpene of Centella asiatica, was well known for wound healing effect. In traditional medicine, C. asiatica extracts have been used in the management of central nervous system disorders including neurodegenerative diseases and memory deficit. The present research was designed to investigate the potential ability of C. asiatica extract and asiaticoside to prevent or attenuate the process of neurodegeneration in the in vitro model of homocysteine-induced injuries in cultured neuroblastoma N1E-115 cells. Cell viability and cell death (assessed by MTT reduction and LDH release respectively), glutathione content, and type of cell death were used as the measuring endpoints. Treatment of cultured N1E-115 cells with 1-100 g/ml of Centella asiatica extract or asiaticoside for 24, 48 or 72 hr had no apparent effect on cell viability. Homocysteine, a non-essential sulphur-containing amino acid, induced neuronal injury and death in a concentration-related manner with approximately 50% cell injury occurred after an exposure to 10 mM homocysteine for 72 hr. Pre-treatment with 100 g/ml of Centella asiatica extract or 50-100 g/ml of asiaticoside, and co-treatment with 75-100 g/ml of Centella asiatica extract or 75-100 g/ml of asiaticoside, with homocysteine for 72 hr attenuated homocysteine-induced reduction in cell viability and successive cell death. In addition, Centella asiatica extract and asiaticoside at a concentration of 100 g/ml replenished homocysteine-induced decrease of total glutathione content and attenuated homocysteine-induced apoptotic cell death. In conclusion, the present study suggested that Centella asiatica extract and asiaticoside may possess the marginal in vitro cytoprotective property against homocysteine-induced neuronal injuries. The underlying mechanisms might directly involve antioxidant activity or indirectly involve facilitation of cellular antioxidant defense system of Centella asiatica extract and asiaticoside. In addition, they might antagonize cellular apoptotic cascade of cell death. However, the detailed mechanisms are not fully understood and remain to be further elucidated.
DOI: 10.14457/cu.the.2008.1627
title: Effects of literature-based english instruction on english reading and writing ability of upper secondary school students

description: The objectives of this study were to examine the effects of literature-based English instruction on English reading and writing ability of upper secondary school students. The subjects were 35 upper secondary school students (Grade 12) who studied at Chitralada School and enrolled in the course of English Creative Writing, second semester, academic year 2008. The experiment lasted for 8 weeks. The paired-sample t-test was used to investigate the differences between the students’ mean scores on the pre- and post-test of reading comprehension and the pre- and post-test of writing. The results of the analyses revealed that (1) the post-test mean scores on the reading comprehension test of upper secondary school students were higher than the pre-test mean scores at the significant level of 0.05 and (2) the post-test mean scores on the writing test of upper secondary school students were higher than the pre-test mean scores at the significant level of 0.05. Upper secondary school students improved their English reading and writing ability after receiving literature-based English instruction
DOI: 10.14457/cu.the.2008.1628
title: Effects of task-based writing instruction on english writing ability of upper secondary school students

description: The objectives of this study were to: 1) investigate the effects of task-based writing instruction on students’ writing ability; and 2) explore students’ opinions towards task-based writing instruction. The samples were 35 Grade 10 students at Chulalongkorn University Demonstration Secondary School. They were enrolled in English Writing Through Tasks course in the first semester, academic year 2008. The data were collected quantitatively and qualitatively. A within-group paired-sample t-test was used to investigate the differences between the mean scores from the pre and post English writing test. The qualitative data were analyzed using content analysis and shown in frequency and percentage. The findings of the study revealed that (1) there was a significant difference in students’ mean scores on English writing abilities before and after the students’ participation in task-based writing instruction at the significant level of .05; (2) students reflected towards the benefits and difficulties in the learning logs. They reported that task-based writing instruction enhanced their confidence in writing, developed their writing skills, and promoted their knowledge of vocabulary and grammar. In terms of the limitations, students said that they had problems with language use, vocabulary, and time allocation.
DOI: 10.14457/cu.the.2008.1629
title: Electrocatalytic oxidation of methanol by methanol by metal-carbon nanotube catalysts

description: In this research, the mono-, di-, and tri-metal nanoparticles supported on carbon nanotube (CNT) have been developed as electrocatalysts for the oxidation of methanol using polyol process synthesis. Pt, accompanied by other metals including Ru, Cr, Mo, and Ni, were used as catalysts. Structural information of the metal catalysts on CNT was confirmed by X-ray diffraction (XRD) technique and energy dispersive X-ray fluorescence spectroscopy (XRF-EDX). Transmission electron microscopic (TEM) observation showed that the metal nanoparticles were evenly distributed on CNT. Electrocatalytic properties of the Pt-based metal nanoparticles on CNT towards methanol oxidation were investigated by means of cyclic voltammetry at the scan rate of 50 mV•s–1. Among all of the synthesized catalysts, 2:1:0.5 PtRuMo supported on CNT showed the best electrocatalytic performance with the anodic current of 77.5 A•(g catalyst) –1 for 1.0 M methanol containing 0.5 M sulfuric acid. In addition, the optimized PtRuMo on CNT had high reproducibility and long term stability.
DOI: 10.14457/cu.the.2008.1630
title: Expression and regulation of genes encoding quinoprotein alcohol dehydrogenases in Pseudomonas putida HK5

description: Pseudomonas putida HK5 produces three different quinoprotein alcohol dehydrogenases, ADH-I (qedA), ADH-IIB (qbdBA) and ADH-IIG (qgdA). Gene organization of qedA, the gene for ADH-I, and other 10 genes in the cluster was related to the genome sequences of five other Pseudomonas strains. Insertion mutations in either qedA, exaE, or agmR eliminated ADH-I activity, although the mutants were still able to grow on ethanol but at a slower rate than that of the wild-type strain. In addition, roles of genes encoding two response regulators, exaE or agmR, located downstream of qedA were inferred from the properties of exaE- or agmR-disrupted mutants and the gene complementation results. Both exaE and agmR gene products were strictly necessary for qedA transcriptions, although there may be other sensing regulatory factor(s) involved. Mutant analysis demonstrated the tentative involvement of agmR, but not exaE, in the induction of ADH-IIB and ADH-IIG activities. The promoter activities of genes involving in alcohol oxidation were determined using a transcriptional lacZ fusion promoter-probe vector. Ethanol was the best inducer for the divergent promoters of qedA and qedC encoding ADH-I and a cytochrome c, respectively. Primary and secondary C3-, C4-alcohols and butyraldehyde specifically induced the divergent promoters of qbdBA and aldA encoding ADH-IIB and an NAD-aldehyde dehydrogenase, respectively. The qgdA promoter of ADH-IIG was well responded to S-(+)-1,2-propanediol induction. The hypothetical regulatory network scheme of three distinct alcohol dehydrogenases in the oxidation system of alcohol in P. putida HK5 was derived.
DOI: 10.14457/cu.the.2008.1631
title: Extraction and purification of lutein fatty acid esters from marigold flower

description: This study aims optimize process for purification of free lutein obtained from marigold flowers. First, saponification was carried out to convert lutein fatty acid esters in the marigold oleoresin to free lutein . Then, further purification of free lutein could be achieved by crystallization. At a fixed temperature of 75 ºC, we determined the effects of saponification conditions such as time (0-7 hrs), volume to weight ratio of KOH solution to oleoresin (0.3ml: 1g-1ml: 1g), and the concentration of KOH solution (25%-45%) on the concentration of free lutein. The results showed that the concentration of free lutein increased with an increase in time up to 4 hrs, where the maximum concentration was obtained. Extended saponification above 4hrs resulted in observable product degradation. For saponfication of 1 g of oleoresin at 75 C for 4 hr, the suitable volume of KOH solution and concentration of KOH solution were found to be0.5ml and 40% v/v, respectively The volume and concentration higher than 0.5ml and 40% caused product degradation as free lutein is unstable at extreme pH. After saponification, the purity of free lutein was improved by crystallization. The effect of the system of crystallization solvent (water to ethanol and water to isopropanol), the volume ratio of crystallization solvent (2:0.3-2:1 v/v), and crystallization time (0.25-2 hrs) on the yield and purity of free lutein were studied. The suitable crystallization process was found to be that employing 2:0.5 (water to ethanol) and the crystallization time was 0.5 hrs. The purity and yield of free lutein as analyzed by HPLC were found to be 85.53% and 99.12%, respectively.
DOI: 10.14457/cu.the.2008.1632
title: Formulation and physicochemical characterisation of fenofibrate-loaded lipid nanoparticles

description: The aims of this thesis were to develop fenofibrate-loaded lipid nanoparticles (FLNs) in both dispersion and freeze-dried forms, and to study the effects of process parameters on theirs physicochemical properties and their stability. The formulations studied were composed of lipid excipients and surfactant mixtures. These lipid excipients were cetyl palmitate (CP) wax, medium-chain triglycerides (MCT) oil, and one of four glycerides either trimyristin (TM), hydrogenated palm oil (HPO), glyceryl behenate (GB) or glyceryl palmitostearate (GPS), while the surfactant mixture was made of polysorbate 80 and lecithin. The samples were prepared by hot high pressure homogenisation technique. The results revealed that an increase in the homogenised cycle and pressure brought a decrease in the particle size of FLNs. They were also affected by the types and amounts of the lipid and the surfactant concentrations. A formulation containing either GPS or GB diglycerides as co-lipid was found to be capable of generating particles in the 30 nm range. For the freeze-dried forms, the small particle sizes could be maintained by using hydrophilic surfactants which were not crystallised during the freeze-drying process, with high amount of cryoprotectant or without. DSC and X-ray diffraction studies on freeze-dried form revealed that the freeze-drying process had no impact on the polymorphic transformation of lipids. Most formulations showed β′ form while the formulation containing TM as co-lipid revealed the combination of stable β form and metastable β′ form. Although those formulations have some different in lipid modification, the high drug entrapment was achieved in dispersion and freeze-dried form but the former had a poor dissolution. However, the stability data demonstrated that FLNs and their freeze-dried products remained stable, both physical and chemical, over 3 months at 30 °C.