cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.14457/cu.the.2006.1896
title: Detection of natural rubber latex allergens using antibody conjugated with fluorescent dye-doped silica nanoparticles

description: In this research, the tris (2,2’-bipyridyl dichlororuthenium (II) hexahydrate: Rubpy)-doped silica nanoparticles (DSNP) were synthesized by using a water-in-oil microemulsion method. The DSNP are shown to be uniform spherical shape with average diameter of 65 +- 5 nm. The surfaces of DSNP were modified and conjugated with antibody against skim latex protein antigen (31 and 39 kilodalton) and antibody against concentrated latex protein antigens (100 kilodalton). After conjugation with antibody, the DSNP were apparently uniform in size, 50+-2 and 51+-2 nm respectively. Utilization of the DSNP conjugated with antibody against skim latex proteins and concentrated latex protein antigens for the detection of protein antigens in natural rubber latex and rubber products indicated that this method is specific and showed very high sensitivity with detection limit at 0.01 ng/muL for both of skim latex antigen and concentrated latex antigen. On the contrary, the Enzyme-Linked ImmunoSorbent Assay (ELISA) exhibited signals at the detection limit only 1 ng/muL. This newly developed method using DSNP conjugated with antibody showed 100-fold higher specificity, and 4-time more rapid than ELISA. In addition, this method is practical and economic,because sample can be used with no need for concentration or purification, the trace amount of sample is enough to be determined by using DSNP conjugated with antibody as nanoprobe.
DOI: 10.14457/cu.the.2006.1897
title: Corporate governance and cost of external equity of IPOs underpricing

description: This thesis empirically investigates the effects of corporate governance on the cost of external equity. In particular, this thesis examines the association between the investor protection and IPOs underpricing. Employing a large sample of IPOs from 10 countries during 1991 and 2005, the results show that investor protection affects underpricing; especially, the legal enforcement. This thesis also finds evidence that IPOs in bank based economies experience lower underpricing than IPOs in market based economies. The finding also suggests that the legal enforcement and liability standard through securities law play a significant role in mitigating information asymmetry. Overall, this thesis empirically demonstrates, for the first time based on cross-country evidence, the importance of investor protection as well as the certification role of bank monitoring to the cost of external equity.
DOI: 10.14457/cu.the.2006.1898
title: Quantitative analysis of marker dyes from cardanol and nitro aniline in diesel using high performance liquid chromatography

description: The quantitative analysis of marker dyes from cardanol and nitro aniline in diesel using high performance liquid chromatography (HPLC) with UV-VIS detector was studied. The sample preparation was performed using silica column chromatography. The column was eluted with hexane and toluene, respectively. The quantitative determination of marker dyes was carried out suing C [subscript18] column (250 x 4.60) mm), methanol/0.2% acetic acid in water with ratio 95:5 as mobile phase, flow rate 0.80 mL/min, wavelength detection at 390 nm. Excellent linear coefficient of 0.9979 was obtained by constructed standard calibration in a range of 1.00-12.0 mg/L. Satisfactory method efficiency was evaluated from recovery and intra- and intermediate precision and the quantitation limit is 2.50 mg/L of marker dyes in diesel fuel. Moreover, the measurement of the amount of this marker dye in diesel stored for 3 months was studied. It was found that marker dye was stable in diesel. Therefore, the developed HPLC method can be used for quantitative determination of marker dyes from cardanol and nitro aniine in diesel with short analysis time, small volumes of sample, and provide quantitative measurement of marker dye to confirm qualitative measurement in the field test.
DOI: 10.14457/cu.the.2006.1899
title: Role of angiotensin in renal dihydrofolate reductase, GTP-cyclohydrolase 1 and nitric oxide synthase expression in renal ischemic reperfusion

description: Renal ischemic reperfusion (IR) enhances angiotensin II (ANG II) level. In cell culture study, ANG II suppresses dihydrofolate reductase (DHFR) but not modulate GTP-cyclohydrolase 1 (GTP-CH 1) expression. Both enzymes are required for synthesis of BH4 which plays a crucial role in dimerization of nitric oxide synthase (NOS). There is no simultaneous study the role of ANG II on renal DHFR, GTP-CH 1, NOS gene and protein expression during IR. Male Wistar rats were divided into two main groups: sham (S) or IR (30-minute renal pedical occlusion and reperfusion for 1 day). Both groups were further treated with 1) water, or 2) angiotensin converting enzyme inhibitor (ACEI; Enalapril ; 5 mg/kg/day), or 3)angiotensin II receptor type 1 blocker (ARB; Losartan ; 10 mg/kg/day) for one day before S or IR and continuously for 1 day after the operation. On each experimental due date, 24-hr urine and blood samples were collected. The serum was determined for electrolytes, blood urea nitrogen, creatinine (Cr), and Cr clearance (CCr). The kidneys were removed for RNA isolation, detection of mRNA expression (RT-PCR), and protein abundance (Western blot) for DHFR, GTP-CH 1, endothelial NOS (eNOS), and inducible NOS (iNOS). The data show that IR decreased DHFR mRNA and protein levels (p&lt;0.01) which were restored by ACEI (p&lt;0.05) or ARB (p&lt;0.01); whereas GTP-CH 1 expression was remained. IR suppressed the eNOS dimer (p&lt;0.01) while enhanced the monomer (p&lt;0.01) which were corrected by ACEI or ARB (p&lt;0.01). The renal eNOS mRNA and total eNOS protein levels did not change in all experimental groups. IR increased iNOS mRNA, total iNOS protein, and iNOS monomer (p&lt;0.01) which reduced by ACEI or ARB (p&lt;0.01). The present study demonstrates the first evidence indicating that IR, via stimulation of ANG II, suppresses renal DHFR but activates iNOS both mRNA and protein expression. IR enhances the monomer while diminishes the dimer form of eNOS. Inhibition of ANG II by using ACEI or ARB could restore DHFR and eNOS dimer whereas attenuate the heightened levels of iNOS expression and NOS monomer. IR has no effect on GTP-CH 1 expression. The present result also indicates that angiotensin II receptor type 1 play a crucial role in modulation of DHFR and NOS expression.
DOI: 10.14457/cu.the.2006.1900
title: Population ecology and conservation of the river terrapin, Batagur baksa (GRAY, 1831) in Myanmar, Thailand and Malaysia

description: This study confirmed that Batagur baska small populations still persists in coastal regions of Mon and Rakhine states and Ayeyarwady and Tanintharyi Division in Myanmar where a combination of local religious beliefs and areas of armed conflict confer some degree of protection. Peninsular Malaysia represents the last stronghold of B.baska and this study estimates indicate that less than 50 breeding females remain in Perak River, Malaysia. A small numbers of B.baska still inhabited in Langu Canal in Satun Province, Thailand and also documented the occurrence of three wild nests and other potential nesting beaches along the river. In Satun Inland Fishery Station, under captive condition, courtship and mating took place during October and November, followed by nesting in December and January. Mean clutch size among females (n=14) was 21.7 +- 5.6 eggs (range = 18 to 25 eggs). Incubation periods ranged from 74 to 110 days depending on the method of incubation. Hatching success ranged from 40.8 % to 58.1 % depending on incubation method. In Bota Kanan Hatchery, courtship and mating takes place from August through December, while nesting and clutch deposition occurs as early as October, with a peak in January, and continues until mid-March Clutch size produced by captive female averaged 15.2+-5.7 eggs (n=10;range = 6-20). From 1993 to 2005, 1524 clutches were produced by adults maintained at BKH with hatching success ranging from 27.5 to 60.5 %. Incubation periods ranged from 71 to 92 days. Based on 79 females and 50 males, the analysis indicates that there is no significant morphological difference between B.baska among isolated populations and it could only be concluded that B.baska males had significantly narrower carapace width, shallower shells, shorter plastrons, and lighter body weight than those in females at all locations. Batagur baska populations face a variety of threats including predation, incidental capture as a result of fishing activity, habitat loss, subsistence and commercial harvest of eggs and turtles, exposure to environmental pollutants, and global climate change. Due to rapid decline of the wild population of B.baska, the conservation management is urgently needed.
DOI: 10.14457/cu.the.2006.1901
title: การออกแบบวงจรบีบอัดและขยายเชิงลอการิทึมของผลต่าง แบบซีมอสคลาส AB

description: วิทยานิพนธ์นี้นำเสนอการออกแบบวงจรขยายและวงจรกรองคลาสเอบีสำหรับสัญญาณผลต่าง ในเทคโนโลยีซีมอส 0.25 ไมโครเมตร โดยใช้เทคนิคการบีบอัดและแผ่ขยายสัญญาณเชิงลอการิทึม วงจรพื้นฐานที่ออกแบบนี้ประกอบด้วยวงจรบีบอัดสัญญาณเชิงลอการิทึม และวงจรขยายสัญญาณเชิงเอกซ์โพเนนเชียล สำหรับวงจรขยายจะต้องใช้แหล่งจ่ายแรงดันอ้างอิงปรับค่าได้ เพื่อกำหนดอัตราขยายของวงจร ในส่วนวงจรกรอง จะเพิ่มวงจรอินทิเกรตซึ่งทำงานแบบไม่เป็นเชิงเส้น ทั้งวงจรขยายและวงจรกรองนี้ถูกออกแบบให้มีย่านการทำงานของสัญญาณในช่วงความถี่เสียง ช่วงกว้างสัญญาณขาเข้าของวงจรคือ +-1 ไมโครแอมป์ และความถี่ของสัญญาณ 20 เฮิรตซ์ – 20 กิโลเฮิรตซ์ มีแรงดันไฟเลี้ยงต่ำถึง 0.6 โวลต์ วงจรขยายใช้พลังงานต่ำกว่า 3.2 ไมโครวัตต์ เมื่อมีสัญญาณขาเข้าสูงที่สุดในขณะที่มี THD เพียง 0.55% และมี CMRR ถึง 35.76 dB ซึ่งแสดงให้เห็นว่าวงจรที่ออกแบบมีความสามารถในการกำจัดสัญญาณรบกวนโหมดร่วม และใช้พลังงานต่ำ ในส่วนของวงจรกรองที่ออกแบบ จะเป็นวงจรกรองผ่านความถี่ต่ำอันดับที่หนึ่ง ที่สามารถปรับค่าความถี่ตัดได้ถึง 20 กิโลเฮิรตซ์ โดยมีช่วงกว้างสัญญาณขาเข้าและแรงดันไฟเลี้ยงเท่ากับวงจรขยาย วงจรกรองนี้จะใช้พลังงานเพียง 4.29 ไมโครวัตต์เมื่อมีสัญญาณขาเข้าสูงสุด และมีความเพี้ยนเชิงเส้น 0.94% ทั้งนี้เทคนิคและวงจรที่นำเสนอในงานวิทยานิพนธ์นี้ สามารถนำไปประยุกต์ในการออกแบบวงจรรวม โดยเฉพาะอย่างยิ่งในอุปกรณ์พกพาที่มีข้อจำกัดทางด้านพื้นที่และพลังงาน เช่น เครื่องช่วยฟัง.
DOI: 10.14457/cu.the.2006.1902
title: Evolution and palaeoecology of crocodiles in the mesozoic of Khorat plateau, Thailand

description: The Khorat Plateau has yielded so far nine species in six genera of Mesozoic crocodilians, which belong to three difference families. Theriosuchus from the Phu Kradung and Sao Khua Formations, and a Teleosaurid, cf. Peipehsuchus from the Phu Kradung Formation, were recognized as new records in the Khorat Plateau. Siamosuchus phuphokensis from the Sao Khua Formation and Khoratosuchus jintasakulii from the Khok Kruat Formation were erected as new genera and species, whereas Theriosuchus sp. A from the Sao Khua Formation, "Goniopholis" sp. A and "Goniopholis" sp. B both from the Khok Kruat Formation possess unique characters, which are sufficient to recognize these taxa as new species, but they are in need of more preparation before they can be properly described. "Sunosuchus" thailandicus Buffetaut and Ingavat, 1980 and "Goniopholis" phuwiangensis Buffetaut and Ingavat, 1983 were considered as uncertain genera, based on insufficient diagnostic characters. The discovery of a Theriosuchus skull from the Phu Kradung Formation indicates that the distribution of this dwarf Atoposauridae was widespread from Europe through China and Southeast Asia and also suggests that Europe and Southeast Asia has already been connected at that time, but the exact time of the connection between these continents is not exactly known. For "Sunosuchus" and cf. Peipehsuchus, the phylogenetic positions of these taxa are still unresolved, because the former lacks the complete upper jaw, while the latter was described on the basis of isolated teeth only. These two taxa thus cannot be used to decipher the relationship of the faunas between Southeast Asia and China. The disappearance of long-snouted piscivorous crocodilians in the Sao Khua Formation may be caused by a palaeoclimate change from humid environment in the Late Jurassic to semi-arid environment in the Early Cretaceous. Ecological niche of the long-snouted crocodilians seems to be replaced by a fish-eating dinosaur Siamosaurus suteethorni, which is unknown before the deposition of the Sao Khua Formation This hypothesis is supported by the similarity of the enamel microstructure of S.suteethorni and the Mesozoic crocodilians. The broad, short-snouted crocodilians were still diverse in this formation, probably because of their more diverse diet. The Thai "Goniopholis" from the Khok Kruat Formation shows the existence of this form throughout the Early Cretaceous Khorat Plateau, but its phylogenetic affinity is still ambiguous. K. jintasakulii, also described from this formation, is the most advanced elongate-snouted Thai neosuchian, based on the position of the internal choanae, which is almost enclosed by the pterygoid.
DOI: 10.14457/cu.the.2006.1903
title: Effect types of isocyanates on mechanical and thermal properties of benzoxazine and urethane polymer alloys

description: This research aims to investigate the effect of types of isocyanates on mechanical and thermal properties of benzoxazine and urethane polymer alloys. Polybenzoxazine, a new thermoset plastics, possesses various intriguing properties including high thermal stability, easy processability, low water absorption, near zero shrinkage, excellent mechanical properties, as well as ability to alloy with various types of resins. However, one shortcoming of this resin is its rather high rigidity making the polymer unsuitable for some applications. This work aims to develop an approach to further improve properties of polybenzoxazine by alloying with urethane elastomer based on various types of isocyanates such as isocyanates such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and isophorone diisocynate (IPDI). The experimental results showed that glass transition temperature (T [subscript g]) of the alloys at various types of isocyanates increased from 160 degrees celsius of the neat polybenzoxazine to 253 degrees Celsius in the 60:40 BA : PU system and the degradation temperature increased from 321 degrees Celsius to about 330 degrees Celsius with increasing the urethane content for all evaluated compositions. In addition, flexural modulus of the polybenzoxazine decreased from 5.8 to 1.7-2.0 GPa when adding 40 wt% of PU for all BA:PU alloys. Furthermore, the flexural strength showed a synergistic behavior at the BA:PU ratio of 90:10 for all three types of the alloys. The effect of urethane prepolymer based on TDI provided the highest T [subscript g ], flexural modulus, and flexural strength of the alloys among the three isocyanates used (i.e. in comparison at the same urethane content). The optimum isocyanate of the binary systems for making high processable carbon fiber composites was BA:PU based on TDI. The flexural strength of the carbon fiber-reinforced BA:PU based on TDI at 80wt% of the fiber in cross-ply orientation rendered relatively high values of about 490 MPa. The flexural modulus slightly decreased from 51GPa for polybenzoxazine to 48 GPa for the alloys having 40 wt% of the PU fraction.
DOI: 10.14457/cu.the.2006.1904
title: Catalytic study of iron, aluminium, cobalt and vanadium modified titanium silicalites-1 in the hydroxylation of benzene to phenol by hydrogen peroxide

description: This research has studied the catalytic activity of titanium silicalite-1 (TS-1) catalysts modified by Fe Al Co and V were synthesized, characterized and tested in the hydroxylation of benzene by hydrogen peroxide and the effects of pretreatment with nitric acid aqueous solution on the catalytic activity of catalysts. The results of the reaction show that the Fe Al Co and V incorporated in TS-1 framework promoted the catalytic activity higher than TS-1. Especially, the Co-TS-1 catalyst has the highest catalytic activity. After the catalysts were pretreated by nitric acid aqueous solution, the framework structure of catalyst is not destroyed and titanium in the framework is not removed. But, the extra-framework can be removed partly. As a result, the activity of the pretreated catalysts is improved. The catalytic activity of the investigated catalyst is in the following order Co-TS-1 &gt; V-TS-1 &gt; Fe-TS-1 &gt; A1-TS-1 &gt; TS-1. Co-TS-1 is found to be the best one due to it cause the lowest H[subscript2]O[subscript2] decomposition and has the least phenol product deposite on the surface.
DOI: 10.14457/cu.the.2006.1905
title: Effects of 15-minute warm up on core temperature changes and sprint performance inThai female national soccer players

description: การศึกษานี้มีวัตถุประสงค์เพื่อศึกษาผลของการอบอุ่นร่างกายในเวลา 15 นาทีต่อการเปลี่ยนแปลงอุณหภูมิแกนกลางร่างกายและสมรรถภาพการวิ่งเร็วระยะสั้นในช่วงรอบประจำเดือน ของนักกีฬาฟุตบอลหญิงทีมชาติไทย อาสาสมัครนักฟุตบอลหญิงทีมชาติไทยจำนวน 13 คน อายุ 18.8+-1.3 ปี ส่วนสูง 161.23+-4.69 เซนติเมตร น้ำหนัก 54.77+-3.30 กิโลกรัม สมรรถภาพการใช้ออกซิเจนสูงสุด 53.05+-6.66 มิลลิลิตร/กิโลกรัม/นาที รอบประจำเดือน 29.4+-1.07 วัน ทำการอบอุ่นร่างกายในระยะเวลา 15 นาที ซึ่งประกอบด้วยการวิ่งเหยาะๆ ก้าวกระโดดร่วมกับเคลื่อนไหวขา และวิ่งเร็วสลับวิ่งธรรมดา ที่อุณหภูมิแวดล้อม 30.0-35.5 degrees celsius ความชื้นสัมพันธ์ร้อยละ 40-69 ในช่วงต้นของฟอลลิคูล่าร์และช่วงกลางของลูเทียล บันทึกอัตราการเต้นหัวใจขณะพักและระหว่างอบอุ่นร่างกาย บันทึกอุณหภูมิแกนกลางร่างกายขณะพัก ระหว่างอบอุ่นร่างกายและช่วงพักหลังอบอุ่นร่างกายระยะเวลา 45 นาทีทดสอบสมรรถภาพการวิ่งเร็วระยะสั้นเป็นค่าพื้นฐานและทดสอบหลังอบอุ่นร่างกายทั้งสองช่วงของรอบเดือนเพื่อเปรียบเทียบผลของการอบอุ่นร่างกาย ผลการศึกษาพบว่า ขณะพักอุณหภูมิแกนกลางร่างกายช่วงกลางของลูเทียล (37.11+-0.16 degrees celsius) สูงกว่าช่วงต้นของฟอลลิคูล่าร์ (36.79+-0.21 degrees celsius) อย่างมีนัยสำคัญทางสถิติ เมื่ออบอุ่นร่างกายครบ 15 นาที อุณหภูมิแกนกลางร่างกายเพิ่มขึ้น 1.26+-0.41 degrees celsius และ 1.18+-0.33 degrees celsius ในช่วงต้นของฟอลลิคูล่าร์และช่วงกลางของลูเทียลตามลำดับ อัตราการเต้นหัวใจเพิ่มขึ้นจาก 69.33+-8.14 และ 73.15+-6.73 ครั้ง/นาที เป็น 153.67+-20.34 และ 158.38+-15.19 ครั้ง/นาที ในช่วงต้นของฟอลลิคูล่าร์และช่วงกลางของลูเทียล ตามลำดับ ช่วงพักหลังอบอุ่นร่างกายพบว่าอุณหภูมิแกนกลางร่างกายค่อยๆ ลดลง โดยลดลงประมาณร้อยละ 50 ในนาทีที่ 20 ส่วน เวลาที่ใช้วิ่งเร็วระยะสั้นหลังอบอุ่นร่างกายในช่วงต้นของฟอลลิคูล่าร์และช่วงกลางของลูเทียล มีค่าเท่ากับ 5.52+-0.13 และ 5.51+-0.16 วินาที ตามลำดับ ซึ่งน้อยกว่าค่าพื้นฐาน (5.66+-0.13 วินาที) อย่างมีนัยสำคัญทางสถิติ แสดงว่าการอบอุ่นร่างกายระยะเวลา 15 นาทีในสภาพอากาศร้อน สามารถทำให้อุณหภูมิแกนกลางร่างกายเพิ่มขึ้นมากกว่า 1 degrees celsius และเพิ่มสมรรถภาพการวิ่งเร็วระยะสั้นของนักกีฬาฟุตบอลหญิงทีมชาติไทยได้ส่วนอัตราการเต้นหัวใจขณะทำการอบอุ่นร่างกายและสมรรถภาพการวิ่งเร็วระยะสั้นของนักกีฬา ไม่มีความแตกต่างกันในช่วงรอบประจำเดือน
DOI: 10.14457/cu.the.2006.1906
title: Measurements of patient's setup variation in intensity modulated radiation therapy of head and neck cancer using electronic portal imaging device

description: The introduction of IMRT poses new challenges for delivering intended target dose and minimizing dose and toxicity to critical normal structures. For head and neck cancer, reproducible patient positioning throughout the whole treatment course is particularly important due to the proximity of many critical organs. Deviations from the planned irradiation geometry during a treatment session may be systematic or random. Systematic errors occur if the mean irradiation geometry in the fractionated treatment differs differs from the geometry in the treatment plan. The mean deviations are then called systematic errors. Fraction-to-fraction variations around the mean deviation are called random errors. The purpose of this study is to measure the interfraction setup variation of patient undergoing IMRT of head and neck cancer. The data is used to define adequate treatment clinical target volume to planning target volume (CTV-to-PTV) margin. During March to November 2006, the data was collected from 9 head and neck cancer patients treated with dynamic IMRT using 6 MV X-ray beam from Varian Clinac 23EX. Weekly portal images of setup fields which were anterior-posterior and lateral portal images were acquired for each patient with an amorphous silicon EPID, Varian aS500. These images were matched with the reference images from Varian Acuity simulator using the VARiS Vision software, version 7.3.10 Six anatomical landmarks were selected for comparison. The displacement of portal image from the reference image was recorded in X (Left-Right, L-R), Y (Superior-Inferior, S-I) direction for anterior field and Z (Anterior-Posterior, A-P), Y (S-I) direction for lateral field. The systematic and random error for individual and population were calculated. Then the population-based margins were obtained. The total of 168 images ( 27 simulation images and 141 portal images) and 564 match points were evaluated. The results showed that the systematic error ranged from 0 to 7.5 mm and the random error ranged from 0.3 to 4.8 mm for all direction. The population-based margin ranged from 2.4 to 4.9 mm (L-R), 3.9 to 5.0 mm (S-I) for anterior field and 3.4 to 4.7 mm (A-P), 2.6 to 3.7 mm (S-I) for the lateral field. The difference in population-based margins along S-I axis between anterior field and lateral field were observed because the clavicles chosen for anterior field at the shoulder level were less stable than anatomical landmarks chosen for lateral field i.e. skull bones, C1 and C4. These margins were comparable to the margin that prescribed at King Chulalongkorn Memorial Hospital (5-10 mm) for head and neck cancer. These results showed that the population-based margin is less than 5 mm, thus the margin provides sufficient coverage for all of the patients.
DOI: 10.14457/cu.the.2006.1907
title: InGaAs nanostructures grown by droplet molecular beam epitaxy

description: InGaAs ring-shaped nanostructures are fabricated by droplet epitaxy technique using solid source molecular beam epitaxy (MBE). InGa droplet forming conditions have been varied in order to investigate the effect of substrate temperature during InGa deposition and deposited amount of indium (In) and Gallium (Ga) on InGaAs ring-structures. It was found that increasing substrate temperature during InGa deposition resulted in InGaAs rings larger size but lower density since greater diffusion length of metallic In and Ga atoms responsed to 2-dimensional expansion of InGa droplets and coalescence of neighbouring droplets. Also, the increasing InGa amount deposited would result in InGaAs rings larger size. The ring density is also increased when increasing InGa amount between 2-3 ML. However, when increasing InGa amount to 4 ML, the density becomes to decreased. The density is increased again while increasing InGa amount to 5 ML. It was supposed that decrease of ring density was caused from formation of InGa full-layer instead of individual droplets when greater amount of InGa was deposited. Subsequently, newly supplied InGa adatoms would from the droplets above the layer resulting in renewal of the number of the droplet formed. For photoluminescence (PL) measurement, the nanostructures were repeatedly grown under selected droplet forming condition with additional 100-nm GaAs capping layers including GaAs layers grown by migration-enhanced epitaxy and conventional GaAs layers. The analytical optical properties of InGaAs rings are confirmed by the PL spectra of capped InGaAs ring-structures at 77 K. The PL result indicates the high quality crystal. However, PL intensity was found to be low resulting from low density of the ring structures (10 [superscript 8] cm [superscript -2]).