http://dspace.fsktm.um.edu.my/handle/1812/482 Search the Channel search http://dspace.fsktm.um.edu.my/simple-search http://dspace.fsktm.um.edu.my/handle/1812/788 Title: The reproductive biology and ecology of Johannesteijsmannia Lanceolata J. Dransf. (Arecaceae) <br/> <br/>Authors: Chan, Yoke Mui <br/> <br/>Abstract: Johannesteijsmannia lanceolata is a rare species endemic to Peninsular Malaysia, and is threatened by deforestation and seed harvesting for the ornamental trade. Before proper conservation strategies can be implemented for this species, the understanding of its reproductive biology and ecology is crucial for the assessment and prediction of the population viability under such threats. Thus, this thesis aimed to investigate its phenology, breeding system, embryology, and its distribution across topography (ridge, slope and valley) in a 3.2 ha plot in the Angsi Forest Reserve, Negeri Sembilan. Possible conservation measures were discussed. The wild population showed seasonal flowering, while the cultivated population exhibited steady state flowering. Flowering was weakly correlated with rainfall. The reproductive cycle from flowering to fruiting took 14–15 months. Flowers were homogamous, with peak anthesis from 0730–1100 hours, while the stigma was receptive for only one day. Potential pollinators were stingless bees (Trigona sp.) and small flies (Phoridae and Cecidomyiidae). The palm was facultatively selfing with very low fruit set (<0.05 %). The pollen was elliptic, monosulcate with a smooth exine, and lost its viability after one day. The microspore tetrads were tetrahedral (rarely isobilateral), and formed by simultaneous cytokinesis. The ovule was anatropous, crassinucellate and bitegmic. Twin archesporia and T-shaped megaspore tetrads were rare. The embryo sac development was of the monosporic, 8-nucleate Polygonum type. The distribution of the palm differed across topography, with the density highest in valleys (65 individual ha-1), and is likely influenced by seed recruitment, interspecies competition and topographic features. In-situ conservation and a sustainable seed harvesting regime of Johannesteijsmannia lanceolata are strongly recommended, because the species is narrowly endemic, and has a long reproductive cycle with very low fruit set (2–6 mature fruits per fruiting season). ABSTRAK Johannesteijsmannia lanceolata adalah spesies jarang dan endemik di Semenanjung Malaysia, yang menghadapi ancaman daripada pembukaan hutan dan pengutipan biji benih untuk perdagangan tumbuhan hiasan. Sebelum kita dapat melaksanakan strategi pemuliharaan yang sesuai untuk spesies ini, pemahaman mengenai biologi pembiakan dan ekologi palma ini adalah mustahak bagi menilai dan meramal kemandirian populasi di bawah ancaman tersebut. Maka, tesis ini bertujuan mengkaji fenologi, sistem pembiakan, embriologi dan taburan spesies tersebut melintang topografi (rabung, cerun, lembah) di plot kajian 3.2 ha di Hutan Rizab Angsi, Negeri Sembilan. Saranan-saranan pemuliharaan juga dibincangkan. Populasi liar berbunga secara bermusim, manakala populasi yang di tanam berbunga secara berterusan. Korelasi pembungaan dengan jumlah hujan adalah lemah. Kitar pembiakan dari bunga ke buah mengambil masa 14–15 bulan. Bunga adalah homogami, dengan kemuncak antesis dari jam 0730–1100, manakala stigma kekal reseptif selama satu hari sahaja. Kelulut (Trigona sp.) dan lalat kecil dari keluarga Phoridae and Cecidomyiidae berkemungkinan besar adalah agen pendebungaan. Palma tersebut berupaya kacuk sendiri dan kacuk luar dengan penghasilan buah matang yang sangat rendah (<0.05%). Debunga adalah eliptik, monosulkat dengan eksin licin, dan hilang kemandiriannya selepas satu hari. Tetrad mikrospora adalah tetrahedral (jarang isobilateral), dibentuk oleh sitokinesis serentak. Ovul adalah anatropus, krasinuselat dan bitegmik. Arkesporia kembar dan tetrad megaspora berbentuk T jarang ditemui. Perkembangan pundi embrio adalah jenis monosporik Polygonum. Taburan palma tersebut adalah berbeza apabila melintang topografi, dengan kepadatan maksima di lembah (65 individu ha-1), dan mungkin dipengaruhi oleh rekrut biji benih, persaingan interspesies dan ciri-ciri topografi. Pemuliharaan in-situ dan rejim pengutipan biji benih Johannesteijsmannia lanceolata secara lestari adalah sangat disarankan, kerana spesies tersebut adalah endemik, dan mempunyai tempoh kitar pembiakan yang panjang dengan penghasilan buah matang yang sangat rendah (2-6 biji per musim buah). <br/> <br/>Description: Dissertation -- Faculty of Science, University of Malaya, 2009. http://dspace.fsktm.um.edu.my/handle/1812/787 Title: SOA-based fiber ring laser <br/> <br/>Authors: Abdul Hadi Sulaiman <br/> <br/>Abstract: ABSTRACT This dissertation investigates the generation of laser wavelength using a semiconductor optical amplifier (SOA) in conjunction with an array waveguide grating (AWG) and a fiber bragg grating (FBG) in a ring configuration system. The experimental system utilizing the FBG produced a single laser wavelength with a peak power of -27.45 dBm and this value increases to -18.40 dBm as a modulator is applied in the configuration. As the AWG is utilized in the ring configuration, a maximum of four laser wavelengths at an equivalent peak power can be produced. A system with two-cascaded SOAs is configured, as the peak power is higher and the spectral width is wider. A dual wavelength ring laser system is designed and we obtained a peak power of -17.03 dBm and -14.95 dBm at wavelengths of 1530.2 nm and 1532.6 nm respectively. A quad wavelength ring laser is also demonstrated which capable of generating four laser wavelengths at 1531.0 nm, 1533.3 nm, 1535.7 nm and 1538.0 nm, with an equivalent peak power of -20 dBm and channel spacing of 0.24 nm. The design is upgraded by the addition of another SOA and it is found that the average peak power and lasing bandwidth is increased as well. The multiple wavelength ring laser against time showed a stable operation at 80 minutes with negligible fluctuations in the laser wavelength. The demonstrated laser configurations have the advantage of stable multiple wavelengths, a simple and compact design as well as their potential in various applications of sensors and DWDM system. ABSTRAK Dissertasi ini mengkaji penghasilan saluran laser menggunakan pengganda optik semikonduktor (SOA) bersama-sama dengan susunan jeriji yang memandu gelombang (AWG) dan jeriji Bragg gentian optik (FBG) di dalam sistem konfigurasi gelang. Sistem eksperimen menggunakan FBG menghasilkan satu saluran laser dengan kuasa puncak - 27.45 dBm dan nilai ini meningkat kepada -18.40 dBm apabila sebuah pemodulasi dimasukkan ke dalam konfigurasi. Apabila AWG digunakan di dalam konfigurasi gelang, maksimum empat saluran laser pada kuasa puncak yang sama boleh terhasil. Sistem dengan dua SOA yang disusun secara sesiri telah dikonfigurasi dimana kuasa puncak lebih tinggi dan keluasan spektral lebih luas. Satu sistem laser gelang dua saluran telah direka dimana kita telah mendapat kuasa puncak -17.03 dBm pada saluran 1530.2 nm dan kuasa puncak -14.95 dBm pada saluran 1532.6 nm. Laser gelang empat saluran juga telah ditunjukkan dimana ianya berupaya menghasilkan empat saluran laser pada panjang gelombang 1531.0 nm, 1533.3 nm, 1535.7 nm and 1538.0 nm dengan kuasa puncak yang sama pada -20 dBm dan selang saluran 0.24 nm. Rekaan tersebut telah ditingkatkan dengan penambahan satu lagi SOA dan didapati kuasa puncak purata dan jalur lebar saluran masing-masing meningkat. Laser gelang saluran berganda melawan masa menunjukkan operasi yang dijalankan selama 80 minit ini adalah stabil dengan naik-turun yang boleh diabaikan pada saluran laser. Konfigurasi-konfigurasi laser yang telah ditunjukkan mempunyai kelebihan pada saluran bergandanya yang stabil, rekaannya yang mudah serta padat dan juga potensinya pada pelbagai aplikasiaplikasi pengesan dan sistem DWDM. <br/> <br/>Description: Dissertation -- Faculty of Science, University of Malaya, 2009. http://dspace.fsktm.um.edu.my/handle/1812/731 Title: Optimization and characterization of 130 NM CMOS transistor design using TCAD simulation <br/> <br/>Authors: Hani Noorashiqin Abd. Majid <br/> <br/>Abstract: ABSTRACT Microelectronic device manufacture encompasses the fabrication, testing and simulation, of structures utilized in a variety of application specific integrated circuits. The fabrication of transistors, traditionally from elemental silicon wafer is conducted in a clean room environment utilizing various types of equipment. Process simulation is a critical element in facilitating the optimization of fabrication stages, confirming test results and theoretical models and providing physical insight into structural operation. TSUPREM-4 and MEDICI are two simulators that had been calibrated and used in this work. As device sizes are scaled down, novel structures are proposed such as halo (pocket), lightly doped drain (LDD) and source/drain process. In order to characterize and optimize Silterra 130 nm CMOS transistor design, TCAD simulation is done in this work and the results is compared with measured data and was verified to be in the Silterra specification range. Various doses, implant energies and tilt angle is used to upgrade the transistor performance, reduce the short channel effect and increase the transistor lifetime. Halo implant, lightly doped drain (LDD) implant and source/drain (S/D) implant is the three drain engineering structure to be characterized in this work. It is found that at certain dose, implant energy and tilt angle, the best saturation drain current, Idsat and threshold voltage, Vt that can match the specification target for NMOS and PMOS transistor can be achieved. It is also proved in this work that by using process and device simulator, the correct process can be predicted and the physical insight of the structure such as current flow lines and doping concentrations can be further analyzed. ABSTRAK Pengeluaran peranti mikroelektronik merangkumi pembuatan, menguji dan simulasi, struktur-struktur yang digunakan dalam pelbagai aplikasi khusus litar-litar bersepadu. Pembuatan transistor, terdiri daripada wafer silikon asas dikendalikan dalam satu persekitaran tempat bersih dengan menggunakan pelbagai jenis peralatan. Proses simulasi adalah satu unsur penting yang membantu dalam mengoptimumkan peringkatperingkat pembuatan, mengesahkan hasil percubaan dan model-model teori dan menyediakan fahaman secara fizikal ke atas operasi struktur. TSUPREM-4 dan MEDICI adalah dua jenis simulator yang telah ditentukurkan dan digunakan dalam tugas ini. Setelah saiz-saiz peranti telah diturunkan, struktur-struktur novel telah dicadangkan seperti proses implant halo ‘halo (pocket)’, ‘lightly doped drain (LDD)’ dan proses ‘source/drain’. Dalam peringkat untuk mencirikan dan mengoptimumkan rekabentuk transistor CMOS Silterra 130 nm, simulasi TCAD telah dijalankan dalam projek ini dan hasil-hasilnya telah dibandingkan dengan data yang telah diukur dan telah disahkan ia berada di dalam julat spesifikasi Silterra. Pelbagai dos, tenaga mengimplan dan sudut mengimplan digunakan untuk menaiktaraf prestasi transistor, mengurangkan kesan saluran pendek dan menambah jangka hayat transistor. Implan halo, ‘lightly doped drain (LDD)’ dan proses ‘source/drain’ adalah tiga jenis struktur kejuruteraan parit yang akan dikaji dalam kerja ini. Didapati, dengan dos tertentu, tenaga implan dan sudut condong implan, arus parit tepu, Idsat dan voltan ambang, Vt yang terbaik dapat menepati sasaran spesifikasi bagi transistor NMOS dan PMOS. Dalam kerja ini ia dapat dibuktikan bahawa dengan menggunakan proses dan alat simulator, proses yang menepati spesifikasi dapat diramal dan struktur dalaman seperti aliran arus dan kepekatan pengedopan seterusnya dapat dianalisa. <br/> <br/>Description: Dissertation -- Faculty of Science, University of Malaya, 2007. http://dspace.fsktm.um.edu.my/handle/1812/620 Title: Comparison of esterases between life stages and sexes of resistant and susceptible strains of vector mosquitoes <br/> <br/>Authors: Selvi Subramaniam <br/> <br/>Description: Dissertation (M.Sc -- Faculty Science, University of Malaya, 2009. http://dspace.fsktm.um.edu.my/handle/1812/602 Title: System analysis and design of Musaceae genetic resources knowledge base <br/> <br/>Authors: Rohana Che Nordin <br/> <br/>Abstract: System Analysis and Design of Musaceae Genetic Resources Knowledgebase was about a unique database of data mining with a combination of Imaging and Checklist Database and Genetic Resources itself and was first develop in Malaysia and also over the world. Application ‘Checklist Decision Support’ helps to identify the species of Musaceae (according to ‘Flora of Malaya by Hottum). Imaging database storing the specimen voucher digitally was also the first developed system. This database can support the common software that had been used by taxonomist like BRAHMS and DELTA. This integration data has been name as “BANANA (Musaceae) GENETIC RESOURCES DATABASE SYSTEM (BGRDS)”. The methodology of this project contains using the software of Case Studio 2.16 and FileMaker pro 7.Besides it includes the image capturing and storage in the data under ‘Data Capture, Clean Up and Interpretation’. This database hopefully gives a lot of advantages to researchers and students by its contents and design. This database was designed to become the first developed system which has a unique database and useful potential to taxonomist, genetic conservations, scientist and public. <br/> <br/>Description: Dissertation -- Faculty of Science, University of Malaya, 2004. http://dspace.fsktm.um.edu.my/handle/1812/597 Title: Application of Eichhornia crassipes (water hyacinth) and Pistia stratiotes (water lettuce) as tertiary wastewater treatment agents <br/> <br/>Authors: Siti Zulaikha Othman <br/> <br/>Abstract: ABSTRACT Eichhornia crassipes (Mart.) Solms (water hyacinth) and Pistia stratiotes L. (water lettuce) were studied to gauge the effectiveness of nutrients, bacteria and heavy metals removal in domestic and small-scale industry sewage of Kuala Lumpur city. Both were grown in approximately 68 L wastewater with 21-days retention period in fiberglass tanks. Readings for water temperature, turbidity, specific conductance, pH, dissolved oxygen (DO), chlorophyll a, ammonium-nitrogen (NH4-N) and nitrate-nitrogen (NO3-N) were taken in-situ every five days, whilst analysis for total suspended solid (TSS), biochemical oxygen demand (BOD5), chemical oxygen demand (COD), alkalinity, nitrite-nitrogen (NO2-N), orthophosphate (PO4-P), enumeration of total bacteria, heavy metals (Cd, Cu, Zn) content were done in the laboratory. Water temperature with plants was in the range of 24.9oC to 27.5oC; whilst the mean for pH in the E. crassipes and P. stratiotes microcosms were 7.3 and 7.7 respectively. The removal efficiency by both plants was in the range of 50 to 93% for BOD5, 9 to 75% for COD, and 6 to 100% for TSS. An increase in the concentration of dissolved oxygen from 4 to 52% was also observed although in some cases there was a decrease in the concentration of DO. There were drastic drops in not only NH4-N but also NO3-N content in the water. The range of decrease of NH4-N was from 30 to 96% in both tanks. However, untreated water had a higher removal efficiency of NH4-N (99%) compared to the treated water due to the consumption by the algae which has been observed had grew in the tanks. In contrast, NO3-N content in the water was found to have been removed greatly by both plants from 0.2 to 12.7 mgL-1 and PO4-P content from 1.51 to 6 mgL-1 compared to the untreated water which was from 14 to 28.2 mgL-1 (NO3-N) and from 5.3 to 11.1 mgL-1 (PO4-P). Enumerations of total bacteria decreased from 30 to 81%, although the number of colonies formed sometimes were higher with root’s plants presence. As well as chlorophyll a or algae concentration which the growth were inhibited by the macrophytes and decreased from 20 to 52% compared to the control. The heavy metal concentrations in the sewage also dropped (Cd, 94.7%; Cu, 92%; Zn, 95.2%) as they were efficiently absorbed by both macrophytes especially by their roots, leaves and followed by stems (E. crassipes). In overall, the sewage effluent quality was much improved after undergo the treatment. ABSTRAK Kajian terhadap Eichhornia crassipes (Mart.) Solms (keladi bunting) dan Pistia stratiotes L. (kiambang) telah dijalankan bagi menguji tahap keefisienan untuk mengurangkan kandungan nutrien, bakteria dan logam berat dalam air kumbahan domestik dan industri kecil-kecilan di Kuala Lumpur. Tumbuhan diletakkan di dalam tangki yang berisi kira-kira 68 L air kumbahan selama 21 hari. Bacaan suhu air, kekeruhan, konduktiviti, pH, oksigen terlarut, klorofil a, nitrogen-ammonium (NH4-N) dan nitrogen-nitrat (NO3-N) diambil secara in-situ setiap lima hari, manakala analisis untuk jumlah pepejal terampai (TSS), keperluan oksigen biokimia (BOD5), keperluan oksigen kimia (COD), alkaliniti, nitrogen-nitrit (NO2-N), ortofosfat (PO4-P), penjumlahan bakteria dan kepekatan logam berat (Cd, Cu, Zn) dilakukan di dalam makmal. Suhu air yang mengandungi tumbuhan adalah dalam julat 24.9 oC hingga 27.5oC; manakala purata untuk pH air tangki E. crassipes and P. stratiotes adalah masing-masing 7.3 and 7.7. Keefisenan kedua-dua tumbuhan dalam pengurangan BOD5 adalah 50 hingga 93%, 9 hingga 75% (COD), dan 6 hingga 100% (TSS). Peningkatan oksigen terlarut dari 4 to 52% turut diperhatikan walaupun terdapat beberapa penurunan. Terdapat penurunan yang ketara bagi kandungan NH4-N (30 hingga 96%) dan NO3-N dalam air kedua-dua tangki tumbuhan. Bagaimanapun, air kumbahan yang tidak dirawat mempunyai kadar pengurangan yang lebih tinggi berbanding air yang dirawat akibat penggunaannya oleh alga. Sebaliknya, kandungan NO3-N dalam air yang dirawat oleh kedua-dua tumbuhan telah mengurang dengan banyak dari 0.2 hingga 12.7 mgL-1 dan kandungan PO4-P pula dari 1.51 hingga 6 mgL-1 berbanding air yang tidak dirawat iaitu dari14 hingga 28.2 mgL-1 (NO3-N) dan dari 5.3 hingga 11.1 mgL-1 (PO4-P). Penjumlahan bakteria telah mengurang sebanyak 30 hingga 81%, walaupun adakalanya bilangan koloni yang terbentuk lebih tinggi dengan kehadiran akar tumbuhan. Begitu juga dengan jumlah klorofil a yang pertumbuhannya dihalang oleh tumbuhan akuatik sebanyak 20 hingga 52% berbanding kawalan. Kandungan logam berat di dalam air kumbahan juga menurun (Cd, 94.7%; Cu, 92%; Zn, 95.2%) kerana keefisienan penyerapan oleh kedua-dua tumbuhan terutamanya oleh bahagian akar, daun dan diikuti oleh bahagian batang (E. crassipes). Kesimpulannya, kualiti air kumbahan yang dihasilkan adalah lebih baik selepas melalui rawatan. <br/> <br/>Description: Dissertation -- Faculty of Science, University of Malaya, 2009. http://dspace.fsktm.um.edu.my/handle/1812/582 Title: Pyrolysis of empty oil palm fruit bunches using the quartz fluidised- fixed bed reactor <br/> <br/>Authors: Mohamad Azri Sukiran <br/> <br/>Abstract: In this study, pyrolysis of oil palm empty fruit bunches (EFB) was investigated using a quartz fluidized-fixed bed reactor. The effects of pyrolysis temperatures, particle sizes, heating rates, different oil palm biomass and different type of fluidised beds material on the yields of the products were investigated. The temperature of pyrolysis and heating rate were varied in the range 300-700 ºC and 10-100 ºC min-1 respectively. The particle size was varied in the range of <90, 91-106, 107-125 and 126-250 μm. EFB, trunk, frond and fiber were used to investigate effect of different oil palm biomass on pyrolysis yields. Meanwhile, zircon sand, spent bleaching earth and spent bleaching earth washing with hexane were used to investigate effect of different type of fluidised bed material on pyrolysis yields. The products obtained from pyrolysis of EFB were bio-oil, char and gas. The maximum bio-oil yield was 42.28% obtained at 500 ºC, with a heating rate of 100 ºC min-1 and particle size of 91-106 μm. The maximum product yield of char was 41.56% obtained at pyrolysis temperature of 300 ºC, heating rate of 30 ºC min-1 and particle size of 91 – 106 μm. Meanwhile, the optimum yield of gas was 46.00% could be achieved at the pyrolysis temperature of 700 ºC, heating rate of 30 ºC min-1 and particle size of 91 – 106 μm. The calorific value, total ash, density, total acid, moisture content, pH and elemental analysis of bio-oil were determined. Characterisation of the char includes calorific value, surface area, total volume pore and elemental analysis. The gases detected were carbon monoxide, carbon dioxide, methane, ethane and ethylene depending on the pyrolysis temperature. <br/> <br/>Description: Dissertation -- Faculty of Science, University of Malaya, 2008. http://dspace.fsktm.um.edu.my/handle/1812/581 Title: Analysis of phytonutrients from palm concentrates by high performance liquid chromatography <br/> <br/>Authors: Chandrasekaram, Kumuthini <br/> <br/>Abstract: Palm phytonutrient concentrates is one of the by-products obtained during the production of palm biodiesel. Palm phytonutrient concentrates had been proved to have a far higher concentration of phytonutrients than in crude palm oil with carotenes (20000-25000ppm), tocols (19000-20000ppm), sterols (15000-16000), squalene (2900- 3100) and coenzyme Q (1500-1600ppm). This makes palm phytonutrient concentrates an ideal starting material for palm phytonutrients based studies and production. Palm phytonutrients are extremely sensitive towards heat. Usually at normal room temperature is enough to cause phytonutrients to disintegrate. Based on these factors, samples of palm phytonutrient concentrates were analysed at two different temperatures. A set of samples were stored at room temperature with a temperature range between 28-32°C. Another set of samples were refrigerated at a temperature between -14 to -18°C. The results showed that the loss of concentration in the phytonutrients occurred in both samples. However, samples that stored at room temperature suffered a huge amount of loss up to 70% of its initial concentration. On the other hand, the refrigerated sample only suffered a loss of 10% to its initial concentration. Palm phytonutrients extracted at high concentrations would be ideal to be consumed as supplements as they are all natural. Apart from that, good quality phytonutrients are also effective standard reference materials. Bearing this theory, palm phytonutrients were separated into groups and isolated using common chromatography techniques such as open column chromatography, flash chromatography and High Performance Liquid Chromatography (HPLC). Open column and flash chromatography was successfully utilized to separate palm phytonutrients into groups of carotenes, squalene, tocols and coenzyme Q. Flash chromatography was preferred for its efficiency. HPLC isolation of tocols was accomplished with α-tocotrienol, γ-tocotrienol and α-tocopherol extracted at high concentrations of 640000- 940000ppm. Squalene and coenzyme Q were concentrated to more than 800000ppm. Apart from that, five components of carotenes were also identified in palm phytonutrient concentrates namely lycopene, α-carotene, β-carotene, phytoene and phytofluene. <br/> <br/>Description: Dissertation -- Faculty of Science, University of Malaya, 2009. http://dspace.fsktm.um.edu.my/handle/1812/580 Title: Antimicrobial and cytotoxicity activities of selected marine fungi in Malaysia and bioassay-guided fractionation and isolation of antimicrobial metabolites from Fasciatispora nypae <br/> <br/>Authors: Nazura Zainuddin <br/> <br/>Abstract: The first part of this study on biodiversity involved four locations in Peninsular Malaysia namely, i) Langkawi Island; ii) Jarak and Sembilan Islands; iii) Morib and iv) Port Dickson. A total of 123 marine fungi were recorded, that included 111 ascomycetes, 10 anamorphic fungi and two basidiomycetes. The most common fungi in Langkawi Island are Dactylospora haliotrepha and Leptosphaeria australiensis. In Jarak and Sembilan Island, the most common fungi recorded were L. australiensis and Verruculina enalia. However, in Morib, Neolinocarpon globosporum, Halorosellinia oceanica and Rhizophora marina were the most common fungus encountered, while in Port Dickson, the most common fungi identified were D. heliotrepha, Massarina velatospora, H. oceanica and Kallichorma Tethys. Isolated fungal cultures were evaluated for their antimicrobial activity using two methods: i) plug assay, ii) disc diffusion assay. The plug assay was used as a preliminary screening method for antimicrobial activity and revealed 82 strains (43.4%) out of 152 marine fungi possessed antimicrobial activity against yeasts and bacteria. From the number of active marine fungi, 7 species (10.6%) showed a broad spectrum antimicrobial activity against yeast and bacteria. Most of the strains of marine fungi exhibited antibacterial activity against the Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus. In this study antibacterial activity was greater than antifungal activity. In the disc diffusion assay, crude ethyl acetate extracts of five marine fungi namely, Caryosporella rhizophorae, Fasciatispora nypae, Melaspilea mangrovei, Leptosphaeria sp. and Ascomycete sp.19 (NF) were selected for antimicrobial testing. Results showed that incubation time and culture conditions affected the production of secondary metabolites of marine fungi and varied between species. Fasciatispora nypa produced good activity after 35 days from static culture against Candida albicans and Saccharomyces cerevisiae, whereas C. rhizophorae produced active metabolites from shake culture with good activity achieved after 35 days incubation period against Escherichia coli and B. subtilis. Leptosphaeria sp. and M. mangrovei produced good active metabolites after 15 days cultivation against B. subtilis, S. aureus and 30 days against B. subtilis, respectively from static culture. Ascomycete sp.19 (NF) produced active metabolite at stationary phase with high activity achieved at 15 days incubation period against B. subtilis. Cytotoxic activity was screened by an in vitro assay system of growth inhibition against breast cancer cell line (MCF-7) using crude extract of C. rhizophorae, F. nypae, M. mangrovei, Leptosphaeria sp. and Ascomycete sp.19 (NF). Study showed that only two marine fungi, F. nypae and C. rhizophorae exhibited cytotoxic effect against MCF-7 tested at 100 μg ml-1, where the ED50 value of C. rhizophorae was 14.5 μg ml-1, and, ED50 value of F. nypae was 24 μg ml-1. Bioassay-guided fractionation was performed on the crude extract of Fasciatispora nypae and yielded three active fractions; fraction 2, fraction 5 and fraction 6. One pure compound was successfully isolated from fraction 5 and determined as 2,2,7-trimethyl-2H-1-benzopyran-5-ol. This compound displayed antimicrobial activity against yeasts and bacteria, with weak activity against S. aureus, C. albicans and S. cerevisiae and moderately active against B. subtilis and against and active against Schizosaccharomyces pombe in disc diffusion assay. However, the MIC value of this compound showed that it exhibited weak activity against all bacteria and yeasts with MIC value of >12.5 mg ml-1 against S. aureus, C. albicans, S. cerevisiae and B. subtilis and 10.4 mg ml-1 against S. pombe. <br/> <br/>Description: Dissertation -- Faculty of Science, University of Malaya, 2008. http://dspace.fsktm.um.edu.my/handle/1812/578 Title: The structure and trophodynamics of the fish community in estuaries of Matang Mangrove Forest Reserve, peninsular Malaysia <br/> <br/>Authors: Amy Then, Yee Hui <br/> <br/>Abstract: A total of 41,113 fishes from 94 species of 37 families were sampled by otter trawling in six Matang mangrove subtidal estuaries during a one-year study from June 2004 to May 2005. The Matang Mangrove Forest Reserve (MMFR) current fish checklist totaled 154 species. Sixteen species accounted for 90% of the total catch biomass, which were dominated by the Ariidae, Scatophagidae and Sciaenidae. Mean biomass and abundance of fishes for Matang estuaries were 7.1 g m-2 and 0.3 individual m-2 respectively. Mean abundance and biomass were not significantly different (p> 0.05) between months, estuaries and seasons. Neap catches in Sungai Jaha yielded significantly higher species number, biomass and abundance (mean biomass = 2.2 g m-2) compared to that of spring (mean biomass = 1.1 g m-2) (p<0.01). Higher daytime catches (mean biomass = 2.1 g m-2) versus night catches (1.3 g m-2) could be attributed to high water turbidity and low predation pressure inside the estuaries. Three recruitment peaks of marine migrants into MMFR estuaries were detected, which were related to monsoon seasons and food (zooplankton) availability. Feeding ecology and trophic organization for the MMFR fish community were elucidated, with seven distinctive feeding guilds identified. Copepod was the most important food item volumetrically. The Natantia-feeding guild contained the highest number of fish species and relatively more diet generalists compared to other guilds. However, year-round food abundance within the MMFR estuaries afforded many diet specialists with lower niche breadth. Diet flexibility and wider niche breadth were adopted as feeding strategies to reduce inter-specific competition in species sharing common food resources. High species diversity and complexity of trophic relationships characterized the MMFR fish food web. Stable isotope studies revealed varying contribution of three primary producers to the δ13C signatures of fish consumers. Juveniles of marine species generally showed higher assimilation of phytoplankton carbon while resident estuarine species relied more on mangrove carbon for their nutrition. The range of δ15N enrichment in different fish species relative to their primary food sources span 1-2 trophic levels. These findings further affirm MMFR’s role as an important nursery and feeding ground for many juvenile fish species. <br/> <br/>Description: Dissertation -- Faculty of Science, University of Malaya, 2009.