cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.14457/cu.the.2005.1695
title: Gelatin production from large animal raw hide using proteolytic enzyme extracted from papaya latex

description: This work is divided into two parts: crude extraction of proteolytic enzyme from papaya latex, and the use of crude extracted proteolytic enzyme to produce gelatin via the hydrolysis of raw hide. From the results of solvent extraction of proteolytic enzyme using water and phosphate buffer pH6, the yield of extracted enzyme did not change by extraction time but it was dependent on the solvent and the ratio of latex to solvent. The yield of extracted enzyme from water extraction was higher than those from phosphate buffer extraction. Following the solvent extraction, the extracted enzyme was precipitated in 45% saturated ammonium sulfate solution. The yield and activity of precipitated enzymes were considerably decreased. Therefore, crude extracted enzyme from water extraction at ratio of 1:1 was selected to be used in gelatin production comparing to the use of commercial papain. For the gelatin production, the effects of conditions which were temperature, pH, hydrolysis time and enzyme to raw hide ratio, on the yield of gelatin recovery and properties of gelatin were investigated. At the beginning of hydrolysis reaction, the yield of gelatin recovery was greatly increased, and then slightly increased. The optimum conditions of crude extracted enzyme and commercial papain hydrolysis for the highest gelatin recovery are 75 degrees celsius and pH 7. The percentage of gelatin recovery is around 60-70wt%. The results showed that the gel strength and viscosity of gelatin obatined from both types of enzymatic hydrolysis are low. However, gelatin recovery and properties of gelatin could be manipulated by temperature, pH, and ratio of enzyme to raw hide. For example, at the optimum condition for enzyme activity (75 degrees celsius, pH7), the high gelatin recovery could be achieved but the low gel strength gelatin (55.8-58.4 g Bloom) was obtained. On the other hand, at the condition for relatively low enzyme activity (85 degrees celsius, pH7), the lower gelatin recovery was reached and gelatin with relatively higher gel strength (166.4-187.6 g Bloom) was received. The gelatin recovery and properties of gelatin obtained from crude extracted enzyme and commercial papain hydrolysis were similar. But the used amount and the cost of crude extracted enzyme from papaya latex were much less than those of commercial papain.
DOI: 10.14457/cu.the.2005.1696
title: Effects of cerium dioxide addition on the properties and photocatalytic activities of CeO[subscript 2]/TiO[subscript 2] catalysts for photocatalytic oxidation of ethylene

description: A series of cerium dioxide/titanium dioxide (CeO[subscript 2]/TiO[subscript 2]) photocatalysts were prepared via a sol-gel method and were calcined at 300 ํC for 2 hr. A mixed oxide consisted of TiO[subscript 2] as the major phase and CeO[subscript 2] as the dopant phase in the range of 0-10% mol. Properties of ceria-titania mixed oxides have been investigated using X-ray diffraction (XRD), nitrogen physisorption, inductively coupled plasma atomic emission spectroscopy, UV-Visible absorption spectroscopy, electron spin resonance, fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities of CeO[subscript 2]/TiO[subscript 2] catalysts were evaluated for the degradation of ethylene under UV illumination. The experimental results demonstrated that the photocatalytic activities of CeO[subscript 2]/TiO[subscript 2] catalysts dramatically decreased with increasing ceria content. This decrease was dueto the smaller amount of Ti[superscript 3+] surface defects, smaller band-gap energy, and fewer hydroxyl groups on the catalyst surface. However, when alcohol (i.e., methanol and 2-propanol) was employed as a reactant, we obtained the highest photocatalytic acitivity for the oxidation of alcohol with the mixed oxide catalyst that contained. 0.5% mole of ceria. This result can be explained by different reaction pathways.
DOI: 10.14457/cu.the.2005.1697
title: Performance analysis of solid oxide fuel cell system fueled by methanol

description: This thesis investigates performance of Solid Oxide Fuel Cell (SOFC) system fed by methanol. Two types of solid electrolyte, i.e. oxygen-ion (SOFC-O[superscript 2-]) and proton-conducting (SOFC-H[superscript +]) electrolyte are considered. The thesis consists of three main parts, firstly, determination of inlet steam: methanol ratio at boundary of carbon formation, secondly, comparison of theoretical performance between two types of electrolyte and different of flow pattern (i.e. mixed flow (MF) and plug flow (PF)) and, lastly, investigation on benefit of application of palladium membrane reactor in SOFC-O[superscript 2-] system. It was found from the thermodynamic calculation that the minimum steam: methanol ratio for which carbon formation is thermodynamically unfavoured decreases with increasing temperature. Comparison between the two types of electrolyte reveals that the SOFC-O[superscript 2-] requires lower steam for the prevention for carbon formation due to the water formed by the electrochemical reaction at the anode side. In the efficiency point of view SOFC-H[superscript +] shows higher efficiency than SOFC-O[superscript 2-]. It is demonstrated that the maximum efficiencies decrease with increasing temperature and follow the sequence: SOFC-H[superscript +] (PF) &gt; SOFC-O[superscript 2-] (PF) &gt; SOFC-H[superscript +] (MF) &gt; SOFC-O[superscript 2-] (MF). The corresponding inlet steam: methanol ratios are at the carbon formation boundary for the SOFC-O[superscript 2-] electrolyte, but are about 1.31.5 times the stoichiometric ratio for the SOFC-H[superscript +]. Although the benefit from the lower steam requirement is realized for the SOFC-O[superscript 2-], the use of the SOFC-H[superscript +] electrolyte in the SOFCs is more promising in the theoretical consideration. Finally, it was found that for the SOFC system equipped with Palladium membrane reactor, at the same electrical efficiency of the conventional SOFC system the system requires smallerSOFC stack; however, additional cost of the membrane is required.
DOI: 10.14457/cu.the.2005.1698
title: Series and product expansions for elements in function fields and characterizations of rational elements

description: It is well-known that a positive real number can be uniquely represented as an infinite series or as an infinite product in many different forms, such as, base representations, Sylvester series, Engel series, Luroth series, and Cantor products. Most of these representations also have counterparts in the file of p-adic numbers. Starting from 1987, A. Knopfmacher and J. Knopfmacher introduced two major general algorithms, one for product and the other for series expansions, which give unique representations for p-adic numbers. Such algorithms embrace all the above-mentioned expansions as special cases. The aims of this thesis are to carry over the Knopfmachers algorithms to the case of function fields and to investigate the possibility of characterizing rational elements via these expansions. By function fields, we refer to F[subscript q]((p(x)) an F[subscript q]((1/x)), the completions of the field of rational functions F[subscript q](x) with respect to the p(x)-adic valuation and the infinite valuation, respectively, where p(x) is an irreducible polynomial over F[subscript q] Following the processes similar to those of the Knopfmachers, in the first part, the algorithms for constructing series and product expansions for elements in the fields F[subscript q]((px))) an F[subscript q]((1/x)) are described. Detailed proofs of their convergence, uniqueness and the degrees of approximation are proved together with examples derivable from these algorithms. The second part deals with the problem of characterizing rational elements in both fields through their series and product expansions. Using the concept of digit set as expounded in the works of the Knopfmachers, it is found that all, but one, series expansions represent rational elements if and only if they are finite. In the exceptional case, the Luroth-type perhaps the hardest case, it is shown that rational elements correspond either to finite or periodic expansions. The characterization of rational elements is deemed complete for series expansions. This is in stark contrast to the p-adic case where this problem remains open in a few cases. Regarding product expansions, only one particular type, called Cantor product expansion, which is constructed from one of the series expansions, the Type 4 expansion, is completely characterized using the result from the series case. Sufficient conditions for rationality are established for the remaining cases. This again is more favorable than in the p-adic case where only some sufficient conditions are known for ll such product expansions.
DOI: 10.14457/cu.the.2005.1699
title: Synthesis of polyureas and polyurethanes containing heterocycles

description: This research involved the synthesis of heterocyclic polyureas, polyurethanes and polyurethane-ureas, which was done by the polymerization reaction of heterocyclic compounds containing diamine and diol functional groups with disocyanate compounds at the mole ratio 1:1. The heterocycles used were proflavine (PF), new fuchsin (NF) and bromphenol blue (BPB). The diisocyanates employed were isophorone diisocyanate (IPI), 4,4 methylenebis (phenyl isocyanate) (MDI), tolylene 2,4-diisocynate terminated poly (1,4-butanediol) prepolymer (PB900) and tolylene 2.4-diisocynate terminated poly (propylene glycol) prepolymer (PP1000). The reaction between isophorone diisocyanate (IPI) and different heterocycles were studied to obtain the information on the reactivity of diamine group or diol group in heterocyclic compounds towards diisocyanate group in the polymerization reaction. The progress of polymerization reaction was followed by using infrared spectroscopy. The disappearance of isocyanate peak at 2270 cm (supperscript -1) was observed when the polymerization was completed. The obtained information in this step was used in the synthesis of heterocyclic polyureas, polyurethanes and polyurethane-ureas in the next step. The polymers were characterized by FTIR spectroscopy, NMR spectroscopy, elemental analysis, solubility and viscometry. Heat resistance of polymers was investigated by thermogravimetric analysis (TGA) and measuring limiting oxygen index (LOI) values. It was found that the polyureas based on proflavine and new fuchsin showed good thermal stability.
DOI: 10.14457/cu.the.2005.1700
title: Effects of metal-doping on zinc oxide nanoparticles synthesized via solvothermal method

description: This research studies properties of metal-doped ZnO nanoparticles synthesized via solvothermal method, i.e. thermal decomposition of zinc acetate in 1, 4-butanediol, at 220 degree Celsius for 2 h. The physical properties of the product were investigated by XRD, SEM, XPS and UV/Vis. Doping of Ga, Cu, Al and Mg as the secondary metal at metal content 0 -12.5 at. % into ZnO crystals during solvothermal sysnthesis and calcinations at temperature 300-900 degree Celsius were also investigated. It was found that Ga and Al incorporated in ZnO crystal structure affected properties of ZnO nanoparticles. Blue-shift in UV absorption spectrum from Ga and Al doping indicated a change in electronic states of the product. An increase in the content of Ga and Al doping resulted in further shift in the UV absorption spectrum. Addition of the secondary metal also affected morphology of the synthesized particles. Calcination resulted in red-shift in UV absorption spectrum of Ga- and Al-doped zinc oxide. For Cu and Mg doping, the properties of as-synthesized samples were the same as undoped ZnO, but calcinations caused blue-shift in UV absorption spectrum of Mg-doped ZnO because ZnO was alloyed with Mg by calcinations at temperature higher than 700 degree Celsius. The photocatalytic degradation of methylene blue and the photoluminescence spectra were also employed to investigate properties of metat-doped ZnO.
DOI: 10.14457/cu.the.2005.1701
title: การสกัดแลนทานัมไอออนผ่านเยื่อแผ่นเหลวที่พยุงด้วยเส้นใยกลวง

description: งานวิจัยนี้ได้ตรวจสอบการสกัดแลนทานัมไอออนโดยใช้กรดไดเอทิลเฮกซิลฟอสฟอริก (D2EHPA) เป็นสารสกัดละลายในน้ำมันก๊าดเป็นสารละลายเยื่อแผ่นเหลว สารละลายเยื่อแผ่นเหลวถูกพยุงไว้ในรูจุลภาคของเส้นใยกลวงชนิดไม่ชอบน้ำ และได้ศึกษาผลกระทบของตัวแปรต่างๆ ในกระบวนการนี้ได้แก่ ความเข้มข้นของแลนทานัมไอออนในสารละลายป้อนอยู่ในช่วง 1 ถึง 1000 ส่วนในล้านส่วน, ความเข้มข้นของสารสกัด D2EHPA ในช่วงความเข้มข้น 0.1 ถึง 1.0 โมลต่อลิตร, ค่า pH ในสารละลายป้อนในช่วงที่มีความเป็นกรด, ความเข้มข้นของกรดซัลฟูริกในสารละลายสตริปในช่วงความเข้มข้น 0.05 ถึง 0.5 โมลต่อลิตร และการเพิ่มความเข้มข้นของแลนทานัมไอออนในสารละลายสตริป ผลการทดลองแสดงให้เห็นว่า อัตราการถ่ายโอนมวลของแลนทานัมไอออนมีค่าเพิ่มขึ้นตามความเข้มข้นของแลนทานัมไอออนในสารละลายป้อนเมื่อความเข้มข้นของสารสกัด D2EHPA มีค่ามากกว่า 0.5 โมลต่อลิตร แต่เมื่อสารสกัดมีความเข้มข้นของแลนทานัมไอออนจะไม่มีผลต่ออัตราการถ่ายโอนมวล สำหรับความเข้มข้นของสารสกัดในช่วงความเข้มข้น 0.1 ถึง 0.5 โมลต่อลิตร อัตราการถ่ายโอนมวลเพิ่มขึ้นตามความเข้มข้นของสารสกัด อย่างไรก็ตามอัตราการถ่ายโอนมวลจะมีค่าคงที่เมื่อความเข้มข้นของสารสกัดสูงกว่า 0.5 โมลต่อลิตร จากการทดลองนี้พบว่าค่า pH มีผลต่อร้อยละการสกัดโดยได้ค่าร้อยละการสกัดสูงสุดที่ pH เท่ากับ 2.5 และพบว่าการปรับ pH ในสารละลายป้อนด้วยกรดไฮโดรคลอริกดีกว่าการใช้สารละลายบัฟเฟอร์ นอกจากนี้ยังพบว่าไม่มีผลกระทบต่อการสกัดเมื่อใช้กรดซัลฟูริกที่มีความเข้มข้นสูงกว่า 0.25 โมลต่อลิตร และสุดท้ายกระบวนการสกัดด้วยเยื่อแผ่นเหลวที่พยุงด้วยเส้นใยกลวงนี้สามารถเพิ่มความเข้มข้นให้กับแลนทานัมไอออนในสารละลายสตริปโดยการแพร่จากสารละลายป้อนที่มีความเข้มข้นต่ำไปยังสารละลายสตริปที่มีความเข้มข้นสูงกว่าได้
DOI: 10.14457/cu.the.2005.1702
title: Stochastic model development and simulation of agglomerative deposition of aerosol on an electret fiber

description: Unlike ordinary filters, the initial high collection efficiency of the electret filter (E) might briefly fall as dust load increases. Here, the electrical enhancement factor of the electret fiber (lambda [subscript E] under dust-loaded condition for uncharged and charged particles is obtained from published experimental results. It is found that the collection efficiency of the electret fiber (eta) can be approximated as the sum of the electrical and mechanical collection efficiency. The predicted values of E are shown to agree well with reported experimental observations for both uncharged and charged particles. In addition, a three-dimensional stochastic model is extended to simulate collection and agglomeration of particles on the cylindrical electret fiber. Effect of interception, induced force (for uncharged particles) and coulombic force (for charged particles) parameters are studies. For both charged and uncharged particles, when the interception parameter is small, captured particles are densely packed. The effect of high electrical forces on the morphology makes the dendrites taller, straighter and more slender than those of small electrical forces. Next, the dust-loaded collection efficiencies of four identical electret filters with the same average packing density but different spatial distributions of packing density along the filter thickness are calculated and compared. The results show that we can significantly lengthen the filter service life by packing the filter loosely on the inlet side and progressively more densely towards the outlet side.
DOI: 10.14457/cu.the.2005.1703
title: Catalytic performance of zirconia and mixed oxide zirconia catalysts in isobutene synthesis from synthesis gas

description: The catalytic performances of various zirconia, ceria and zirconia-ceria mixed oxide catalysts on isosynthesis were studied. The characteristics of the catalysts were determined by using various techniques including BET surface area, XRD, NH[subscript 3-] and CO[subscript 2]-TPD, and SEM/EDX. For micron- and nanoscale zirconia and ceria catalysts, it was found that nanoscale catalysts showed higher activity and selectivity of isobutene in hydrocarbons than micronscale ones. The acid-base properties and phase composition of zirconia influenced the catalytic performance. Effect of temperature ramp during calcination was also investigated. Lower heating rate of calcination exhibited an increase in monoclinic phase in zirconia. The studies revealed that higher selectivity of isobutene in hydrocarbons was resulted from higher intensity of Zr[superscript 3+] and/or more fraction of tetragonal phase present. The catalytic performances of zirconia-ceria mixedoxide catalysts prepared by coprecipitation and physical mixing method were studied. The major factor determining the activity and selectivity of isobutene was the amount of Zr[superscript 3+]. Intensity of Zr[superscript 3+] decreased when ceria was added to zirconia for both preparation methods. It was observed that the physical mixing method exhibited better selectivity of isobutene in hydrocarbons than coprecipitation method in lower content of ceria of 69.2%. It revealed that quantity of Zr[superscript 3+] in the former method was higher than that of the latter. Therefore, it was concluded that the difference in the quantity of Zr[superscript 3+] influenced the catalytic performance of the catalysts. Furthermore, the suitable reaction temperature for isosynthesis was 400 ํC.
DOI: 10.14457/cu.the.2005.1705
title: Effect of defected zirconia support on catalytic activity of carbonmonoxide hydrogenation

description: In this study, the modified Pechini method has been used to prepare alumina-zirconia mixed oxides varied in a range of 25-75% by mole of alumina in zirconia. To compare with the mixed oxides, pure alumina and pure zirconia were also prepared by the same method. Physicochemical properties of all samples were investigated and elimination of 2-propanol was used to evaluate the catalytic performance of solid surface. The modified Pechini preparation resulted in poor acid-base strength of alumina surface resulting in high acetone selectivity where imperfect crystal structure of the tetragonal zirconia favoured high propylene production in 2-propanol elimination employed as cobalt catalyst support for CO hydrogenation. Moreover, zirconia with low alumina content (0.5-1 mole% Al) were also prepared and tested as support. When zirconia with low Al content supported Co catalysts increased 30% compared to the ones supported on pure zirconia or pure alumina suggesting the modification of zirconia by alumina resulting in higher Co dispersion. However, when supports with high alumina contents (40-75 mole% Al) were used, low Co dispersion and poor catalytic performance were found. It is likely that cobalt formed metal-support compounds with amorphous phase of these mixed oxides. Finally, tetragonal zirconia with low content of another elements (0.5-1 mole%), i.e. Y or Si was introduced to be Co catalyst support, however the catalytic performances and stabilities of these supports exhibited fairly lower than that of zirconia with low Al content.
DOI: 10.14457/cu.the.2005.1706
title: Preparation of [alpha]-keto acids and [alpha]-keto esters using transition metal carboxylate complexes

description: Screening for nickel (II) carboxylate complexes disclosed that nickel (II) stearate coupled with THBP could catalyze the transformation of ethyl phenylacetate to ethyl benzoylformate as a major product and ethyl mandelate as a minor product. In the case of iron (III) carboxylate complexes, iron(III) trichloroacetate coupled with THBP could smoothly catalyze the transformation of ethyl phenylacetate to ethyl benzoylformate in high yield. The optimum conditions for the oxidation of ethyl phenylacetate including amount and type of catalyst, amount and type of oxidant, solvent, reaction time and reaction temperature were conducted. Utilizing the developed optimum conditions for the oxidation of ethyl phenylacetate, other selected chemical models: ethyl mandelate, ethyl thiophene-2-acetate, ethyl (4-chlorophenyl) acetate, methyl (4-methoxyphenyl) acetate, ethyl (4-methoxyphenyl) acetate, butyl (4-methoxyphenyl) acetate and ethyl p-toluylacetate could be converted to corresponding [alpha]-keto esters in good to excellent yield.
DOI: 10.14457/cu.the.2005.1708
title: ความแม่นยำของกฎสัดส่วนสำหรับความถี่ธรรมชาติของโครงสร้างแผ่นบางรูปสี่เหลื่อมผืนผ้าโดยวิธีการทดลอง

description: วิทยานิพนธ์นี้ศึกษาความแม่นยำของการวัดค่าความถี่ธรรมชาติของโครงสร้างแผ่นบางรูปสี่เหลี่ยมผืนผ้าโดยใช้กฎสัดส่วนสำหรับปัญหาการสั่นสะเทือน โดยกฎสัดส่วนสำหรับการสั่นสะเทือนของโครงสร้างแผ่นบางวัสดุไอโซทรอปิกหาได้จากสมการครอบคลุมและทำการสอบทวนกับผลเฉลยแม่นตรง การศึกษาเป็นการทดลองกับชิ้นงานสองกลุ่มคือ กลุ่มวัสดุชนิดเดียวกันและกลุ่มวัสดุต่างชนิดกัน ชิ้นงานแบบจำลองและชิ้นงานต้นแบบเป็นแผ่นสี่เหลี่ยมผืนผ้าที่มีเงื่อนไขขอบเขตการจับยึดแบบ SSSS SFSS SFSF และ SSFF ทดลองเพื่อหาค่าความถี่ธรรมชาติด้วยวิธีการเคาะ ค่าความถี่ธรรมชาติสามโหมดแรกหาได้จากสัญญาณการสั่นสะเทือนบนโดเมนความถี่นำกฎสัดส่วนมาใช้กับค่าความถี่ธรรมชาติจากการวัดของชิ้นงานแบบจำลองเพื่อทำนายค่าความถี่ธรรมชาติของชิ้นงานต้นแบบ แล้วนำค่าความถี่ธรรมชาติของชิ้นงานต้นแบบที่ได้จากการทำนายมาเปรียบเทียบกับค่าความถี่ธรรมชาติของชิ้นงานต้นแบบจากการวัด จากการเปรียบเทียบค่าความถี่ธรรมชาติจากการวัดและค่าความถี่ธรรมชาติจากการทำนายโดยกฎสัดส่วนค่าเฉลี่ยและค่าส่วนเบี่ยงเบนมาตรฐานเท่ากับ 0.24+-6.51% แสดงให้เห็นว่าการวัดค่าความถี่ธรรมชาติให้ผลความแม่นยำในระดับที่ดีเมื่อเทียบกับการใช้กฎสัดส่วนกับปัญหาการโก่งงอ การใช้กฎสัดส่วนในการหาความแม่นยำของการวัดการสั่นสะเทือนให้ผลดีกว่าวิธีการเปรียบเทียบความถี่ธรรมชาติจากการวัดกับผลเฉลยแม่นตรงเนื่องจากการทดลองไม่สามารถสร้างเงื่อนไขขอบเขตแบบง่ายหรือเงื่อนไขแบบยึดแน่นได้สมบูรณ์ตามอุดมคติ ซึ่งในการใช้กฎสัดส่วนชุดทดลองไม่จำเป็นต้องมีเงื่อนไขที่สมบูรณ์ตามอุดมคติ
DOI: 10.14457/cu.the.2005.1709
title: ตัวปิดล้อมที่สั้นที่สุดสำหรับสี่อาณาบริเวณซึ่งมีพื้นที่ตามที่กำหนด

description: ในวิทยานิพนธ์นี้เราจะหาเงื่อนไขจำเป็นของตัวปิดล้อมที่สั้นที่สุดสำหรับสี่อาณาบริเวณเมื่อกำหนดพื้นที่ของแต่ละอาณาบริเวณให้ กรณี P[subscript 1] = P[subscript 2] = P[subscript 3] &gt; P[subscript 4] เมื่อ P[subscript i] เป็นความดันของอาณาบริเวณที่ i เราพบว่า 1. สำหรับตัวปิดล้อมที่สั้นที่สุดแต่ละเซลล์ของอาณาบริเวณที่สี่มีไม่เกิน 9 ด้าน 2. ถ้าอาณาบริเวณที่สี่เป็นบริเวณเชื่อมโยง แล้วเซลล์ของอาณาบริเวณที่สี่ต้องเป็นเซลล์ข้างนอก