cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.14457/cu.the.2007.1460
title: Ecological roles of renieramycins on the blue sponge Xestospongia sp.

description: The blue sponge, Xestospongia sp., is a coral reef inhabitant occurring in the Gulf of Thailand. The distribution pattern of Xestospongia sp. and its association with other organisms were investigated. The results showed that the most frequently coexisting organisms were the massive coral, Porites lutea, and the colonial zooanthid, Palythoa caesia. However, Xestospongia sp. was also found with algal patches and dead coral rubble. The largest individuals of Xestospongia sp. were found growing on Pa. caesia while the smallest individuals were found on the algal patches. This sponge has been known to produce renieramycins (Frincke and Faulkner 1982). The results also showed that concentrations of renieramycin M, the main alkaloid with highly potent cytotoxicity, extracted from this sponge differed significantly among sites. Carbon-nutrient contents and renieramycin M concentrations were found to be significantly different between the areas of Xestospongia sp. (edge, inner and outer) whereas carbon-nutrient contents and renieramycin M concentration of Xestospongia sp. coexisting with different organisms were not significantly different. In the laboratory renieramycin M did not show any allelopathic effect on its coexisting organisms (Porites lutea). Furthermore, it did not inhibit the growth of aerobic bacteria. However, renieramycin M inhibited settlement of acorn barnacle (Semibalanus balanoides) but did not inhibit the settlement of pelecypods. In the experiments, renieramycin M concentrations increased immediately after Xestospongia sp. was wounded. Renieramycin M was also detected in Jorunna funebris, specifically the predatory nudibranch on Xestospongia sp. (Saito et al. 2004). This study found that the concentration of renieramycin M was not equally distributed into the body parts of Jorunna funebris. The concentration of renieramycin M was decreased by increasing starvation periods. However the feeding deterrent activity was found in tissues of Jorunna funebris, as well as, the renieramycin M. In conclusion, Xestospongia sp. is a reef inhabitant that frequently coexists with Porites lutea and Palythoa ceasia. This sponge produces renieramycin M, the alkaloid substance and distributes it along its body. Although, renieramycin M did not show either allelopathic or anti-microbial effects, it exhibited anti-fouling and anti-feeding effects. Jorunna funebris was found to contain renieramycin M and Jorunnamycin in the mantle and foot muscle. The concentrations of these chemicals decreased when Jorunna funebris was starved.
DOI: 10.14457/cu.the.2007.1461
title: Antioxidant activity of black glutinous rice Oryza sativa L. extracts

description: The objectives of this research were to determine the appropriate solvent and the optimum extraction condition to prepare crude extract from black glutinous rice and to determine the application of the crude extract as an antioxidant and colorant in fish oil enriched mayonnaise. Firstly, the black glutinous rice flour was extracted twice with 50% ethanol (v/v), 70% acetone (v/v), and 50% ethanol (v/v) followed by 70% acetone (v/v), at neutral (pH 6.8) and acidic (pH 2) conditions, for 2, 4 and 8 hours of total extraction times. Total phenolic content, total monomeric anthocyanin content and antioxidant activities, determined by DPPH and FRAP methods, of the crude extracts were measured. Statistical analysis showed that there were significant effects of all three main factors, which were type of solvent, pH of solvent and extraction time, as well as significant two-way and/or three-way interactions of those main factors on each parameter measured (p[is less than or equal to]0.05). Since the best extraction conditions for total phenolics, total monomeric anthocyanins, FRAP and DPPH assays were not agreeable, the most suitable extraction condition was selected from the shortest total extraction time which gave an acceptable amount of total phenolics and total monomeric anthocyanins, and high antioxidant activity. Therefore, the most suitable solvent and condition was the twice extraction with neutral 50% acetone at 4 hour total extraction time. The crude extract from the selected condition was then used to study its application in fish oil enriched mayonnaise. The freeze-dried extract was added into the mayonnaise at two different concentrations, 500 ppm and 1000 ppm (based on oil weight in the mayonnaise). Lipid oxidation in the oil phase of mayonnaise samples stored at 30˚C was determined every 5-7 days up to 30 days by measuring conjugated diene hydroperoxides (CDH) and thiobarbituric acid reactive substance (TBARs). Color of the mayonnaise was also measured in the Hunter (L, a, b) system. The results showed that the crude extract could retard an increase in both CDH and TBARs in the oil phase of the mayonnaise samples during storage. Crude extract at 1000 ppm showed higher antioxidant activity. However, lightness (L) and yellowness (b) of all mayonnaise samples decreased whereas redness (a) of all samples increased during storage which indicated the instability of anthocyanin colorant in the product. The overall results from the application study showed that although the crude extract exhibited great antioxidant activities in fish oil enriched mayonnaise, it could not serve as a good colorant in this product since its pink or light purple color was not stable.
DOI: 10.14457/cu.the.2007.1462
title: Simulation of solid oxide fuel cell system fuelled by ethanol

description: The research focuses on the simulation of solid oxide fuel cell (SOFC) systems fuelled by ethanol. The study is divided into four parts: theoretical performance analysis of ethanol-fuelled SOFC with different electrolyte, actual performance of ethanol-fuelled SOFC, thermodynamic assessment of SOFC system integrated with bioethanol purification unit and design of thermally integrated bioethanol-fuelled SOFC system with a distillation column. The theoretical performance of SOFC with proton-conducting electrolyte (SOFC-H[superscript +]) is found to be superior to that of oxygen ion conducting electrolyte (SOFC-O[superscript 2-]) although the lower requirement of steam input in the case of SOFC-O[superscript 2-] is taken in to account. However, the actual performance of SOFC-H[superscript +] is inferior to that of SOFC-O[superscript 2-] because the resistance is 45.6 times higher than that of SOFC-O[superscript 2-]. In order to develop the performance of SOFC-H[superscript +] to be comparable to that of SOFC-O[superscript 2-], both electrolyte resistance and other resistances should be simultaneously reduced. A bioethanol-fuelled SOFC system integrated with a distillation column (SOFC-DIS) is proposed to improve the conventional system which was fed by high purity ethanol in order to save distillation energy. The combustion heat from excess fuels is provided to other parts of the system i.e. heaters, a reformer and a reboiler. The SOFC-DIS can operate without demanding heat from an external source when suitable operating voltage and fuel utilizations are selected. To improve the performance of SOFC-DIS, utilization of heat released from a condenser and splitting of some part of cathode outlet stream to be recycled offer the highest efficiency and lowest total cost index. The suitable heat exchanger network for the SOFC-DIS system is that the hot stream from the afterburner is first heat exchanged with the anode-inlet heat exchanger, the reformer, the air heat exchanger, the distillate heat exchanger and a reboiler, respectively. In addition, adjusting SOFC-DIS operating conditions can lower total cost index.
DOI: 10.14457/cu.the.2007.1463
title: Factors of quotient rings over some quadratic integer rings

description: Greg Dresden and Wayne M. Dymacek obtained factors of quotient rings over ring of Gaussian integers Z[i]={a+bi/a,b[is an element of a set] Z}. We generalize their idea to obtain factors of quotient rings of the ring of Eisenstein integers Z[omega]={a+b[omega]/a,b[is an element of a set]Z} where [omega]=(-1+[square root]-3)/2 and some other quadratic integer rings Z[omega]={a+b[omega]/a,b[is an element of a set]Z} for [omega]=[square root]d where d is an integer such that d [is equivalent to] 2, 3 (mod 4) or [omega] = (1+[square root]d)/2 where d is an integer such that d [is equivalent to] 1 (mod 4) and in both cases d is squarefree. Moreover, James T. Cross extended naturally the Euler [phi]-function of the ring of integers to the ring of Gaussian integers.We extend it to the ring of Eisenstein integers and some quadratic integers rings.
DOI: 10.14457/cu.the.2007.1464
title: Determination of ground state energy and effective mass of bose systems in random potentials by path integration method

description: We apply Feynman's path integral theory to study Bose-Einstein condensates in a double well potential and in a random potential. The main idea of this thesis is to perform the mean field approximation in two body interaction by the path integral approach. Bose particles are confined in the double well which is taken as a harmonic potential with Gaussian or cosine barrier. Performing the variational calculations we obtain analytical results of the ground state energy, wave functions, and overlap integrals. The overlap integrals enable us to calculate the tunneling rates which are in good agreement with numerical values for the two-mode model of Gross-Pitaevskii's equation. We also consider the model of a Bose system consisting of N particles with finite interacting pair potentials under the influence of random potentials. The porosity or nonhomogeneity of the system can be represented by the density of porosity with amplitude of the fluctuation, and a correlation length. We obtain analytical results of the effective mass and the ground state energy which are in good agreement with that of Bugoliubov approach. The propagator of the system is used to calculate the partition function, specific heat, the critical temperature, condensate density, and the superfluid density of the system.
DOI: 10.14457/cu.the.2007.1465
title: Optimization of supercritical carbon dioxide extraction of essential oil from Amomum krevanh Pierre

description: Supercritical carbon dioxide extraction of essential oil from Amomum krevanh Pierre was studied. The influence of particle sizes of the raw materials on essential oil yields was studied for the particle size range between 180 and 800 [micro]m and the maximum essential oil yield was obtained with the particle size of 250-355 [micro]m. Furthermore, the experimental design and response surface methodology was employed in order to investigate the effects of operating condition and to predict the optimal condition for supercritical carbon dioxide. The factors investigated for essential oil were operating temperature in range of 33-67 [degree Celcius], the operating pressure in range of 91-259 bar, and the extraction time in range of 20-70 min. The results showed that the main effect of operating pressure and the interaction effect between operating temperature and extraction time were significant factors for the essential oil yields. From the response surface model of the experimental data, an optimal condition for essential oil content was found to be at the temperature of 64 [degree celcius], the pressure of 277 bar, and the extraction time of 84 minutes. At this condition, the amount of essential oil yield extracted was 11.90 mg/g dry amomum. The yield obtained by SC-CO[subscript 2] extraction was higher than the amount obtained by organic solvent extraction which was 9.74 mg/g dry amomum. The major compounds obtained by SC-CO[subscript 2] were 1,8-cineole (71.65%), [beta]-pinene (8.64%), and limonene (4.77%) which were similar to that obtained by organic solvent extraction whose compositions was 1,8-cineole (70.86%), β-pinene (7.91%), and limonene (4.30%).
DOI: 10.14457/cu.the.2007.1466
title: Simulation of polymer electrolyte membrane fuel cells

description: This research concentrates on the performance analysis of a polymer electrolyte membrane fuel cell (PEMFC). A two-phase model taken into account the formation of liquid water is used to simulate the steady state behavior of the PEMFC under isothermal condition. The mass transfer resistance of reactants due to a water flooding effect is taken into account to analyze cell performance. The effect of key operating conditions such as temperature, pressure and humidification of reactant gases on the PEMFC in terms of the distribution of gas composition and current density, and cell voltage and power density is studied. Simulation studies show that the performance of PEMFC increases when operating temperatures, the humidity of the fuel gas and air gas, and operating pressure are increased. In contrast, the cell performance decreases while the anode and cathode inlet temperatures increase due to the dehydration of membrane. The water flooding at the cathode side increases with increasing operating current density. The occurrence of water flooding results in lower void fraction in the cathode and thus, less oxygen can diffuse to the catalyst layer. Therefore, higher concentration loss is observed.
DOI: 10.14457/cu.the.2007.1467
title: Electrocatalysis methanol oxidation by metal nanoparticles deposited on boron-doped diamond thin film electrode

description: In this research, the preparation of mono-, di-, and trimetallic catalysts deposited on boron-doped diamond (BDD) thin film electrodes and their applications towards methanol oxidation have been studied. In combination with other metals including ruthenium, rhodium, and gold, the platinum based catalysts were electrochemically deposited on the BDD electrode under potentiostatic conditions. Cyclic voltammetry was used to examine the electrocatalytic activity of the modified BDDs for the oxidation of methanol. Among the prepared electrodes, the platinum–ruthenium–rhodium/BDD showed the best catalytic performance with the anodic current of 17.58 mAcm[superscript -2] for 1.00 M methanol in 0.50 M sulfuric acid. Characterized by means of scanning electron microscope/energy dispersive spectrometry (SEM/EDS), the metal particles deposited on the BDD surface were distributed in the range of nanometers.
DOI: 10.14457/cu.the.2007.1468
title: Effects of configurations of external loop airlift contactor on hydrodynamics and gas-liquid mass transfer

description: Various configurations of external loop airlift contactor (ELALC) were examined for their hydrodynamic and mass transfer behavior using tap water. These behaviors was manipulated by changing the length of connection tubes (L[subscript c]), height of riser and downcmoer (L[subscript h]) and other configurations while keeping the ratio between downcomer and riser cross sectional area constant at 0.269. The results showed that the change of configuration could have effects on: gas holdup, liquid velocity, and gas-liquid mass transfer. Increasing L[subscript c] and L[subscript h] seemed to pose the same effect on the airlift performance. For instance, an increase in L[subscript c] from 20 to 40 cm, and Lp[subscript h] from 100 to 140 cm, could increase liquid velocity at 11.3 and 7.2%, decreased overall gas holdup at 8.6 and 3.3% and decreased the overall volumetric mass transfer coefficient at 8.2 and 5.6%, respectively. The effect of configurations on ELALC was investigated. ELALCs with inclined connection tubes and with close downcomer were compared with regular ELALC in terms of hydrodynamic and gas-liquid mass transfer behaviors. The two configurations presented large agglomerate of gas bubbles on the top connection tubes which resulted in more gas holdups and less downcomer liquid velocity when compared with regular ELALC. The mathematical model was developed based on the mass conservation principals to predict the gas-liquid mass transfer in the ELALC. Basically ELALC was represented by a series of reactors, i.e. the riser, downcomer, top and bottom connection tubes were represented by the dispersion model, and the two gas separators represented by the stirred tank model. The simulation results were found to be reasonably accurate for all experimental conditions employed in this work.
DOI: 10.14457/cu.the.2007.1469
title: A comparative study of adverbs

description: 本論文之宗旨是對現代漢語副詞“再”和“又”在語義上和語法上進行比較研究，此外，還對現代漢語副詞“再”和“又”與泰語/iːk/在語義上和語法上進行比較研究。 研究結果發現漢語副詞“再”和“又”可分爲四大結構：一、跟動詞搭配；二、跟形容詞搭配；三、跟數量詞搭配；四、跟否定副詞“不 / 沒”搭配。現代漢語副詞“再”有五個義項，一、表示一個動作或狀態重複發生或繼續；二、表示一件事在另一件事之後發生；三、表示程度增加；四、表示不滿，責備對方或禁止對方做某事；五、表示另外。漢語副詞“又”有四個義項：一、表示一個動作或狀態重複發生；二、表示補充；三、表示不滿或責備對方，和別人講理或辯駁；四、表示另外。 現代漢語副詞“再”和“又”與泰語/iːk/在語法結構上的比較，研究結果顯示漢語副詞“再”和“又”與泰語/iːk/ 的語法結構很相近，例如：泰語/iːk/可以跟動詞、形容詞、數量詞及否定副詞“不 / 沒”搭配，這一點的功能與漢語副詞“再”和“又”相同。此外，發現漢語副詞“再”和“又” 與泰語/iːk/ 在語法結構上也有區別，例如：泰語/iːk/ 往往出現於動詞後面，漢語副詞“再”和“又”往往出現於動詞前面。 現代漢語副詞“再”和“又”與泰語/iːk/在語義上的比較，發現“再”和“又”都能對應到泰語/iːk/ ,一般都可以用來表示動作或狀態的重復發生，但它們的用法有所區別，例如：“再”用於未然發生的情況；“又”用於已然發生的情況。能對應到泰語/iːk /的“再”除了能用來表示重復發生之外，還能用來表示程度增加。漢語副詞“再”和“又”在不同的上下文除了能對應到泰語/iːk/之外，還能對應到泰語/khɔ̂:j/和/tʰaŋ/, 而沒有表示重復的意思
DOI: 10.14457/cu.the.2007.1470
title: The impact of the integration of The National Access to Antiretroviral Program for people living with HIV/AIDS into the universal coverage scheme at Nan province in Thailand

description: In 2006, the Thai government established antiretroviral therapy as part of health benefits under the Universal Coverage Scheme. This descriptive study purposed to examine HIV/AIDS treatment and the changes during the transition from NAPHA to the UCS. Data were collected from Nan province. Analysis involved the assessment of factors influencing ART under the UCS policy. The findings: obstacles during the transitions were lack of infrastructure development. It also affected drug management and laboratory supply chain and logistics, but not to a severe degree. ARV drug regimen types are not vastly different under either NAPHA or the UCS, therefore; under both programs treatment procedures can be integrated efficiently. The Thai Government should consider excess demand which will likely lead to increase costs, and the social implications. The Ministry of Public Health should take greater responsibility for policy making, instead of the National Health Security Office, and the provincial public health offices also should be given greater responsibilities too.
DOI: 10.14457/cu.the.2007.1471
title: Subsurface water management of multi-stacked gas reservoirs

description: Water production in commingled monobore gas wells has been the crucial problem for maximizing recovery of muti-stack compartmentalized gas reservoirs in Pattani basin, Gulf of Thailand. After one or more sands produce a significant amount of water, the other sands suffer from the effect of hydrostatic backpressure from the produced water because they share the same wellbore. Shutting off water-out sand(s) is the major method to resolve this problem. This study aims to improve sub-surface water management process. The main focus is on the prediction of critical velocity of gas well before it stops flowing and determination of individual zone gas reserve by building muti-tank commingled model and history match surface production and production logging data. By knowing critical gas velocity, best timing for production logging survey before well stop flowing can be planned to identify the water producing sand(s) as well as knowing OGIP of individual sand, better decision on water shut off intervention could be done with higher success ratio. It is hoped that the outcome of the study will be used as the tool to improve reserve management to maximize recovery of these marginal gas reservoirs in the Gulf of Thailand
DOI: 10.14457/cu.the.2007.1472
title: Microwave-assisted extraction of anti-cancer damnacanthal from roots of morinda citrifolia

description: This study investigated the use of microwave-assisted solvent extraction of anti-cancer damnacanthal from root of Morinda citrifolia. The effects of materials size, irradiation time and temperature extraction, types of solvents, ethanol composition, and ratio of liquid to sample on the percent recoveries of the extract were determined. The extraction recovery of the extract was compared with conventional methods including ultrasound and subcritical water extraction. In the study, the percent recovery of damnacanthal was found to be significantly higher for the small particle size material. At 80 C, the percent recovery was lower than that obtained at 60 C due to the decomposition of the compound. The highest recovery obtained at high temperatures of 100 and 120 C was obtained after 5 minute extraction, after which the percent recovery decreased, due to the decomposition of the compound. Of all the solvent tested (acetone, acetonitrile, methanol, and ethanol), acetone gave the highest recovery. Moreover, use of ethanol-water solution as extraction solvent increased the yield of damnacanthal due to the swelling of plant tissue matrix by water and suitable polarity of the mixture, and the appropriate ratio of liquid to sample was found to be 100. When compared with other conventional extraction methods such as soxhlet extraction, ultrasound-assisted extraction, and subcritical water extraction, microwave assisted extraction was more efficient as it required shorter time to achieve the same recovery
DOI: 10.14457/cu.the.2007.1473
title: Learning algorithms for predicting HIV-1 phenotypic drug resistance

description: The limitation of HIV treatment is the decrease of the viral sensitivity to the drug that is called drug resistance. The cause of drug resistance is from the mutations in the reverse transcriptase and protease enzymes of HIV. Thus, resistance testing plays an important role in HIV treatment. In the medical area, there are two methods of resistance testing: genotyping and phenotyping. The advantages of genotypic testing are faster and cheaper than phenotyping. On the other hand, the results of phenotypic method are easier to interpret than genotypic testing. This thesis applied four learning algorithms, which are the Support Vector Machine (SVM), the Radial Basis Function Network (the RBF network), k-Nearest Neighbor (k-NN), and Classification Based on Association (CBA), to construct the models for classifying HIV-1 drug resistance from HIV-1 genotypic data. Further, the predictive behavior of each classification model was studied. Finally, a new dynamic classifier combination method was proposed to construct the composite classifier from these single models. The predictive performances of the learning algorithms were compared with two online drug resistance prediction systems: HIVdb and Geno2Pheno. Our experimental results demonstrated that all learning algorithms yielded the higher average accuracy than that of the online systems. To evaluate the predictive performance of the proposed dynamic classifier combination method, we compared the accuracy with two classifier combination methods which are majority voting and Naïve Bayes. The results showed that our proposed method provided the best average predictive performance.