Biofilm formation by B. licheniformis isolated from whey protein concentrate 80 powder as a potential source of product contamination : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Palmerston North, New Zealand

This study aimed to examine biofilm formation of Bacillus licheniformis isolated from whey protein concentrate 80 (WPC80) as a potential source of contamination in the manufacture of WPC. Six WPC80 powder samples from one whey processing plant in New Zealand were used in this study. Six Bacillus species including (percentage of isolates in brackets) B. licheniformis (66%), Bacillus cereus/Bacillus thuringiensis (18%), Bacillus subtilis (4%), Bacillus pumilus (4%), Paenibacillus glucanolyticus (2%) and Lactobacillus plantarum (6%) were identified using colony morphologies, biochemical tests, species specific PCR and 16S ribosomal DNA gene sequencing and subsequent analysis using the BLAST and Seqmatch databases. Preliminary screening for biofilm formation by the predominant contaminant, B. licheniformis using a microtitre plate assay with the bacteria grown in laboratory medium tryptic soy broth (TSB) at three different temperatures (30°C, 37°C and 55°C) showed most biofilm formation at 37°C with 9/33 isolates forming strong biofilm. In total 13/33 isolates formed strong biofilm at three different temperatures on the polystyrene microtitre plate surface. Subsequent tests for biofilm formation on stainless steel (SS) showed an increased frequency of biofilm formation with 32/33 strains forming strong biofilm in TSB at 37°C. This demonstrates the limitation of the microtitre plate assay for screening for biofilm formation and suggests that biofilm growth of B. licheniformis favours a SS surface. The attachment and biofilm formation was further investigated using SS coupons and reconstituted whey medium at different concentrations (1%, 5%, and 20%). The best medium for B. licheniformis isolates to form biofilm on SS at its best growth temperature (37°C) was 1% reconstituted WPC80. Interestingly, when 1% reconstituted WPC80 was supplemented with lactose and minerals (mainly calcium and magnesium) to replicate the composition of Mozzarella cheese whey before ultrafiltration (UF), the B. licheniformis biofilm counts increased at least by one log. The production of protease enzyme, extracellular polymeric substances (EPS) and nitrate reduction by B. licheniformis showed the potential of B. licheniformis to influence the quality of dairy products. Biosurfactant production by B. licheniformis identified as lichenysin consisting of lipopeptide was detected and this may influence biofilm formation on SS. The inability of the B. licheniformis isolates to ferment lactose as their major carbon source was confirmed by lactose fermentation tests and shows that B. licheniformis is not ideally suited to a dairy environment. The B. licheniformis vegetative cells were found to be heat resistant with a < log10 reduction at the three temperatures tested; 72oC, 75oC and 80°C during 15 s, 30 s and 60 s heating intervals. In order to thrive in a dairy system, synergistic interactions with other microflora were investigated as a possible mechanism to use lactose that has been broken down by other microflora. Lactobacillus plantarum (L. plantarum), another isolate from the WPC80 samples, has the ability to produce glucose and galactose from lactose. This was grown with each of two B. licheniformis isolates (E30C11 and F30C02) with different abilities to form biofilm. Interestingly this did not enhance the growth of B. licheniformis suggesting that another carbon source, most likely whey protein, must provide the energy source for this bacterium in a whey environment. A review of the WPC80 processing plant showed the UF membranes had the largest surface area (3500 – 7500 m2), providing most potential for biofilm growth. However, UF was run at 10°C, too low for the growth of B. licheniformis which has a minimum growth temperature of 20°C. The hypothesis that sections of the processing plant before the UF step are the sites for B. licheniformis biofilm growth was supported by analysing several samples from the raw whey balance tank, clarifier, thermaliser and separator where 7 B. licheniformis strains were isolated. This shows that B. licheniformis is present at several early stages of WPC processing, with the most likely areas for growth being the certain sections of the clarifier, thermaliser and the separator where temperatures are close to the best growth temperature for this bacterium (37°C). Preventing B. licheniformis contamination of WPC needs to focus on adjusting the conditions in these sections of the processing plant to limit biofilm growth. Keywords: dairy, Bacillus species, L. plantarum, lichenysin, stainless steel, membrane processing plant

Coupling strength control in photonic crystal/photonic wire multiple cavity devices

Resonance splitting has been demonstrated for two coupled micro-cavities with control of the free spectral range between the resonance peaks, together with a normalised transmission level of approximately 60%. Coupled micro-cavity-based structures that were separated by two closely spaced in-line coupler sections between the two micro-cavities have also been successfully fabricated and measured. The coupling strength of the two cavities was controlled via the use of hole tapering in the middle section between the two cavities. 2D finite-difference time-domain simulation shows close agreement with the results of measurements

Puisi-Puisi Hadiah Sastera Utusan Melayu-Public Bank: Kajian Gaya Bahasa

Gaya bahasa merupakan satu unsur dalam penelitian keindahan hasil seni sastera, sarna ada dalam bentuk prosa atau puisi. Dengan itu, kajian ini akan meneliti keindahan gaya bahasa yang terdapat dalam sajak-sajak yang telah memenangi Hadiah Sastera Utusan Melayu-Public Bank 1987-1996. Objektif kajian ini ialah untuk mengenal pasti gaya bahasa yang doni man dalam sajaksajak yang telah memenangi siri hadiah ini. Teori dan pendekatan yang digunakan dalam kajian ini ialah stilistik. Ahli-ahli stilistik telah membahagikan pendekatan ini kepada dua jenis, iaitu kajian tentang unsur-unsur ekspresif bahasa yang dapat menampilkan pemikiraan dan perasaan dan kajian tentang gaya bahasa pengarang secara individu. Fokus kajian ini ialah gaya bahasa yang digunakan oleh pengarang yang memenangi hadiah sastera ini. Hal ini bertepatan dengan objektif kajian. Hasil kajian ini menunjukkan bahawa gaya bahasa perbandingan yang merangkumi simile, personifikasi, hiperbola, metafora dan alusi merupakan gaya bahasa yang dominan dalam anal isis sajak-sajak yang telah memenangi hadiah ini, diikuti oleh unsur gaya bahasa penegasan yang merangkumi anafora, epifora, pengulangan frasa dan ayat

Penilaian integriti struktur robi test bed (road bridge interface test bed) di atas tanah lembut

Masalah mendapan kini kian menjadi isu utama apabila pembinaan dijalankan di atas struktur tanah lembut. Beberapa jenis tanah boleh dikelaskan sebagai tanah lembut iaitu tanah gambut, tanah liat dan tanah organik. Pembinaan di atas tanah jenis ini mengundang kesukaran dan menimbulkan pelbagai masalah kerana tanah lembut adalah kurang stabil dan mengalami pengukuhan primer serta pengukuhan jangka panjang apabila penambahan bebanan yang berterusan. Dalam kajian ini, integriti struktur binaan RoBI (Road-Bridge Interface) dikaji untuk menghubungkaitkan parameter seperti mendapan, aras air bawah tanah dan ciri tanah liat lembut. Struktur RoBI telah dibina di Pusat Penyelidikan Tanah Lembut (RECESS) Malaysia di Universiti Tun Hussein Onn Malaysia (UTHM) bagi menjalankan ujian berkaitan jambatan dan jalanraya pada masa hadapan. Ujian geoteknikal terhadap tanah dilakukan pada tempoh awal pemantauan. Manakala ujian integriti tanpa musnah ke atas RoBI dijalankan selama tiga belas (13) bulan yang melibatkan pemantauan mendapan struktur RoBI, pemantauan aras, aras air permukaan, taburan hujan dan suhu persekitaran. Jenis pengukuhan tanah pada sekitar struktur RoBI ini dikategorikan sebagai pengukuhan primer (pekali pengukuhan, Cv=0.08 m2 /tahun) dan masih berlaku pengukuhan tetapi dalam kadar yang sangat perlahan. Hasil kajian juga telah menunjukkan bahawa tahap (rating) penilaian struktur RoBI ini ialah 7 berdasarkan piawaian National Bridge Inspections Standards (NBIS) dan 2 berdasarkan piawaian Jabatan Kerja Raya (JKR) Malaysia. Secara kesimpulannya, struktur RoBI Test Bed ini sudah mencapai tahap integriti yang baik dan sedia digunakan bagi sebarang ujian berkaitan jambatan dan jalanraya. Melalui kajian ini, struktur RoBI ini dapat dijadikan sebagai tapak ujian yang paling ideal untuk sebarang pengujian yang berkaitan jambatan dan jalanraya bagi penyiasatan fenomena mendapan di atas tanah lembut pada masa akan datang. Katakunci: mendapan, tanah lembut, RoBI, aras air permukaa

Realiti Pencapaian Budaya Cemerlang Di Sekolah Dari Perspektif Pelajar

This study focuses on factors affecting the attainment of excellent cultures from the aspect of academic performance and diciplinary problems in fully residential schools in Kedah and Perlis. Among the objectives are to identify the factors which influence the achievement of excellent culture and the relationships among the factors being investigated. This study also attempted to find out negatives factors which bar the achievement of excellent culture in a fully residential school. Four factors were investigated: student factors, peer group factors, school factors and family factors. The sample consisted of 210 form four students randomly chosen from three fully residential schools: Sekolah Menengah Sains Tuanku Syed Putra Kangar Perlis, Sekolah Menengah Sultan Abdul Halim Jitra Kedah and Sekolah Menengah Sains Pokok Sena Kedah. The questionnaire was pilot tested in Sekolah Sultan Mohamad Jiwa Sungai Petani Kedah. The findings indicated that excellent culture differed significantly between and among students based on student factors viz., peer group factors, school factors and family factors. The findings also indicated that excellent culture achievement was positively related with the four factors under study. There were two outstanding factors such as family income and family involvement in the students’ activities. Both factors did not explain the positive relationship and not representing significant predictor for overall excellent culture performance. The findings also indicate that the relationship between the factors were low

New approaches in avoiding gas hydrate problems in offshore and deepwater operation

Oil industry is facing with challenging gas hydrates and flow assurance issues in deepwater developments. The situation is not any better for Brown fields as a result of increasing water cut. The other factor which is playing an increasing role is product quality and environmental concerns, demanding reduction in chemical usage. The current industry practice for hydrate prevention is injecting hydrate inhibitors at the upstream end of pipelines based on the calculated or measured hydrate phase boundary, water cut, worst pressure and temperature conditions, and the amount of inhibitor lost to non-aqueous phases. In general, systematic ways of controlling and monitoring along the pipeline and/or downstream to examine the degree of inhibition are very limited. Monitoring changes in the pipeline pressure drop is inadequate to provide reliable indicator for hydrate formation and deposition. Therefore, early hydrate warning and online hydrate monitoring techniques are demanded to optimise inhibitor dosage, reduce the risk of gas hydrate formation/deposition and the cost of mitigating the blockage in subsea pipelines. The primary part of this thesis is to develop a new approach for early warning system and monitoring against initial hydrate formation. It is known that the formation of hydrates changes the water structure, which is claimed to remain in the aqueous phase for a period of time even after the dissociation of gas hydrates. This change of water structure is hypothesized to be in the form of water memory. Therefore, two hydrate early warning techniques are investigated based on the presence of water memory resulted from hydrate formation. The techniques investigated in this thesis are dielectric properties and onset of ice formation. In this thesis, the new approach demonstrate that dielectric properties at microwave frequencies has the potential to be used as a downstream and online analysis for detecting the initial hydrate formation and/or presence of hydrate particles and/or changes in water structure due to hydrate formation. Characteristic of onset of ice formation by freezing method for water samples with and without hydrate water memory shows that samples with water memory nucleate faster than that without water memory. It is concluded that the new approach described above have potential to be developed for early warning and online hydrate monitoring. The results are very encouraging and could potentially change the industrial approach to gas hydrate control strategy. Low Dosage Hydrate Inhibitors (LDHIs) have been applied in the field to prevent gas hydrate problems by delaying gas hydrate nucleation and/or growth and to prevent agglomeration of hydrates from growing larger enough to plug the flowline. However, the mechanism of hydrate formation and inhibition is still not well understood. It is believed micro-scale investigation could provide vital clues. The second aim of this thesis is to investigate the inhibition mechanism of Low Dosage Hydrate Inhibitors (LDHIs) by visual observation of gas hydrate formation, growth, and morphology by means of high-pressure glass micromodels, multichanel flow conduits, and glass capillary tubes. Extensive novel data and knowledge was generated from these techniques. The finding of this study shows that various hydrate morphologies formed in the presence of different KHIs for Natural Gas Hydrate and Methane Hydrate. It was concluded that these techniques provides a new data to supplement the lacking of knowledge on the kinetics of gas hydrate inhibition and morphologies

The Evaluation Of The Toxic Effect Of Paraquat And Its Mechanism Of Action On Reproductive System Of Male Rats [RA1242.P34 A636 2007 f rb].

Paraquat® - PQ (1,1’ – dimethyl 4,4’ – bipyridillium dichloride) is a nonselective contact herbicide. Its herbicidal and toxicological properties are dependent on the ability of the parent cation to undergo a single electron addition to form a free radical. Paraquat® (1,1’ – dimetil 4,4’ – bipiridilium diklorida) merupakan sejenis racun herbisid bukan selektif. Kesan herbisid dan toksikologinya bergantung kepada keupayaan kompoun utamanya untuk mengubah kepada elekron tunggal dan membentuk radikal bebas

Advancing the performance of one-dimensional photonic crystal/photonic wire micro-cavities in silicon-on-insulator

We present new results that demonstrate advances in the performance achievable in photonic crystal/photonic wire micro-cavities. In one example, a quality-factor value as high as 147,000 has been achieved experimentally at a useful transmission level

Determination of transformer performance index based on dissolved gas analysis

Dissolved Gas Analysis (DGA) is the single most widely used and most effective test to determine transformer’s operation conditions. The detection of gases generated in the transformer is the first available indication of the transformer malfunction. Several methods used to interpret of DGA results but not single method will necessarily give a true indication. In this project, the samples from energise transformers are extracted and analysis of gases evolved from oil degradation due to thermal and electrical faults. Several DGA interpretation schemes will be propose and applied for fault diagnostics. Some of the applied interpretation techniques are IEC 60599, Rogers and Durenburg Ratio, Duval Method and Key Gas analysis. Also, a case study on actual transformer faults is taken into account in this interpretation. The results of the interpretation will represent the condition of the power transformers and needs to quantify into a condition-based DGA index with a purpose to carry out necessary prevention actio