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On comparison of some variation of ranked set sampling
No full textMany sampling methods have been suggested for estimating the population median. In the situation when the sampling units in a study can be easily ranked than quantified, the ranked set sampling methods are found to be more efficient and cost effective as compared to the simple random sampling. In this paper, the superiority of several ranked set sampling methods over the simple random sampling are illustrated through some simulation study. In addition, some new research topics under ranked set sampling are suggested
The prevalence of microbiological contamination in ready- to- eat food and factors affecting it in Melaka
No full textBackground : A cross sectional study was carried out to determine the prevalence of microbiological contamination in ready- to-eat food and factors affecting it in Melaka from February 2008 till May 2008 in collaboration with the Food Safety and Quality Unit and District Health Offices in Melaka Tengah, Alor Gajah and Jasin.
Methods : A purposive sampling of 101 food premises was carried out and 202 ready- to-eat food samples were collected and analysed microbiologically using standard methods. A total of 202 food handlers were randomly selected for questionnaire interview while rectal and nasal swabs were taken from them to determine their healthy carrier status of pathogenic food bacteria.
Results : Results showed that the overall prevalence of microbiological contamination in ready- to-eat food was 35.1%, while prevalence by type of food was 42.0% for main dishes and 9.8% for staple food. The majority of the contaminations were due to coliforms (14.9%), total plate counts (12.4%) and Staphylococcus aureus (3.5%). The mean score for food premise inspection was 77.21 ± 10.32 and the prevalence of healthy carrier status of pathogenic food bacteria among the food handlers was 15.8%. The level of food handling practices among food handlers was influenced by sex (p=0.012) and formal training on food handling courses (p=0.009). There was a significant negative correlation between age and level of food handling practices among the food handlers (r = -0.163; p = 0.02). Poor food handling practices (p=0.02) and poor hygiene status among the food handlers (p<0.01) were factors that influenced microbiological contamination of food samples. A logistic regression analysis showed that poor food handling practices (Odds ratio=3.50; 95% CI=1.35-9.06) and poor hygiene status among food handlers (Odds ratio=13.16; CI=3.65-47.44) were significantly associated with healthy carrier status of pathogenic food bacteria.
Conclusion : Poor food handling practices and poor hygiene status among food handlers were factors that influenced microbiological contamination of ready-to-eat food as well as healthy carrier status of pathogenic food bacteria
Pull-Out and tensile strength properties of two selected tropical trees
No full textA bioengineering technique is gradually being used as an alternative for slope stabilisation design. The effect of vegetation on soil strength, particularly in terms of root reinforcement aspects has therefore become a major interest. However, there is a lack of documentation on the root mechanical properties available especially in Malaysia. In this study, both pull-out and tensile strength of two tropical trees namely Leucaena leucocephala and Acacia mangium were investigated on different stem sizes. L. leucocephala performs the higher pullout strength than A. mangium. The results also show that pullout resistance is much affected by the root than the shoot profiles. In terms of tensile strength, the tensile strength decreases with increasing root diameter, implying the finer root diameter contribute to the higher tensile strength. In both parameters, L. leucocephala exhibits the highest value. The study suggests that L. leucocephala has an added value as a good potential slope plant for slope stabilization work as it exhibits outstanding root mechanical properties. Interestingly, the results also showed that the pullout force was much affected by the tensile strength. It can be concluded that some root and shoot properties do have a great impact on root mechanical properties such as tensile and pullout strengths
Biodiesel production via transesterification of palm oil using NaOH/Al2O3 catalysts
No full textDue to the increase in price of petroleum and environmental concerns, the search for alternative fuels has gained importance. In this work, biodiesel production by transesterification of palm oil with methanol has been studied in a heterogeneous system using sodium hydroxide loaded on alumina (NaOH/Al2O3). NaOH/Al2O3 catalyst was prepared by impregnation of alumina with different amount of an aqueous solution of sodium hydroxide followed by calcination in air for 3 h. The prepared catalysts were then characterized by using x-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR), Brunner-Emmett-Teller surface area measurement (BET), scanning electron microscopy (SEM) and temperature-programmed desorption of CO2 (CO2-TPD). Moreover, the dependence of the conversion of palm oil on the reactions variables such as the molar ratio of methanol/oil, the amount of catalysts used, reaction temperatures and reaction times were performed. The conversion of 99% was achieved under the optimum reaction conditions. The biodiesel obtained was characterized by FT-IR and the pour point was measure
Comparison of mesa and device diameter variation in double wafer-fused multi quantum-well, long-wavelength, vertical cavity surface emitting lasers
No full textLong-wavelength vertical-cavity surface-emitting lasers (LW-VCSELs) have profound advantages compared to traditional edge-emitting lasers offering improved properties with respect to mode selectivity, fibre coupling, threshold currents and integration into 2D arrays or with other electronic devices. Its commercialization is gaining momentum as the local and access network in optical communication system expand. Numerical modeling of LW-VCSEL utilizing wafer-fused InP-based multi-quantum wells (MQW) and GaAs-based distributed Bragg reflectors (DBRs) is presented in this paper. Emphasis is on the device and mesa/pillar diameter design parameter comparison and its effect on the device characteristics
Pemerolehan, analisis dan interpretasi data fMRI: kehubungan efektif dalam korteks auditori primer manusia
No full textKajian ke atas sifat kehubungan efektif dalam korteks auditori dilakukan ke atas lima orang subjek Melayu lelaki sihat berumur antara 20 hingga 40 tahun menggunakan pengimejan resonans magnet kefungsian (fMRI), pemetaan statistik berparameter (SPM5) dan pemodelan dinamik penyebab (DCM). Paradigma pengimejan senyap digunakan untuk mengurangkan artifak bunyi pengimbas di atas imej kefungsian. Subjek dikehendaki menumpukan perhatian kepada stimulus hingar putih yang diperdengarkan secara binaural pada keamatan 70 dB lebih tinggi daripada aras pendengaran manusia normal. Pengkhususan kefungsian dikaji menggunakan perisian SPM5 yang berasaskan Matlab melalui analisis kesan malar (FFX), kesan rawak (RFX) dan konjunksi. Analisis individu ke atas semua subjek menunjukkan pengaktifan bilateral yang tidak simetri di antara korteks auditori kanan dan kiri pada kawasan Brodmann (BA)22, 41 dan 42 melibatkan korteks auditori primer dan sekunder. Tiga kawasan auditori di korteks auditori kanan dan kiri tersebut dipilih untuk penentuan kehubungan efektif melalui pembentukan sembilan model rangkaian. Kehubungan efektif ditentukan ke atas empat daripada lima subjek dengan mengecualikan seorang subjek yang mempunyai koordinat BA22 yang terletak terlalu jauh daripada koordinat BA22 yang diperoleh daripada analisis kumpulan. Keputusan DCM menunjukkan kewujudan kehubungan efektif di antara ketiga-tiga kawasan auditori yang dipilih di kedua-dua korteks auditori. Pada korteks auditori kanan, BA42 dikenalpasti sebagai pusat masukan dengan kehubungan efektif satu arah selari BA42 → BA41 dan BA42 → BA22. Walau bagaimanapun, untuk korteks auditori kiri, pusat masukan adalah BA41 dengan kehubungan efektif satu arah selari BA41→BA42 dan BA41→BA22. Kehubungan di antara kawasan auditori yang mengalami pengaktifan mencadangkan kewujudan lintasan isyarat dalam korteks auditori walaupun semasa subjek mendengar bunyi hinga
A study on the activity concentration of Po-210 in the marine environment of the Kapar coastal area
No full textThe distribution of a natural radionuclide (Po-210) in seawater, total suspended solid (TSS), sediment and marine organisms was quantified using alpha spectrometry at the coastal area of Kapar, Malaysia. It was observed that the Po-210 activity in TSS was much higher than that of water and sediment samples. The ranges of Po-210 activity in organism samples were 4.12±0.11 Bqkg-1 to 7.49±0.14 Bqkg-1 (Arius maculatus), 8.66±0.28 Bqkg-1 to 44.47±0.83 Bqkg-1 (Penaeus merguiensis), 55.59±1.07 Bqkg-1 to 161.68±4.21 Bqkg-1 (Anadara granosa) and 45.70±1.77 Bqkg-1 to 96.44±2.19 Bqkg-1 (Perna viridis). There are significant correlations between the total weight and Po-210 concentration for all the organisms sampled. The concentration factors of Po-210 for the organisms calculated were 1851.42 (Arius maculatus), 14296.58 (Penaeus merguiensis), 95314.84 (Anadara granosa) and 27128.18 (Perna viridis). Therefore, it can be assumed that mollusks can contribute a higher radiation to seafood consumers in the coastal area of Kapa
Pengecaman awal komuniti bakteria sel bahan api mikrob dalam air sisa kumbahan
No full textKajian ini bertujuan untuk menentukan jenis bakteria yang hadir di dalam air sisa kumbahan yang dapat membantu menghasilkan tenaga elektrik dan pada masa yang sama dapat menyingkirkan kandungan karbon dan nitrogen. Kaedah pengesanan kumpulan bakteria yang digunakan adalah teknik penghibridan in situ berpendarfluor (FISH) manakala kaedah tindak balas berantai polimerase (PCR) untuk mengenalpasti bakteria tersebut. Penentuan ciri biokimia menggunakan BIOLOG GEN III MICROPLATE™ turut digunakan. Bakteria yang didapati daripada air sisa dikultur dan ditulenkan di atas agar zat makanan untuk menentukan ciri-ciri morfologi koloni bakteria tersebut. Berdasarkan pencirian koloni dan pewarnaan Gram, sebanyak 21 pencilan telah diperolehi daripada tiga lokasi sampel air sisa kumbahan daripada loji rawatan enap cemar teraktif (enam koloni air sisa mentah; sebelas koloni tangki pengudaraan; empat koloni tangki kitaran enap cemar teraktif). Penentuan awal daripada ketiga-tiga kaedah yang dijalankan tidak dapat memberikan padanan yang tepat dengan hanya mencatatkan kehadiran bakteria pengoksida ammonia (FISH) dan Kurthia Gibsoni (BIOLOG) di dalam sampel tangki pengudaraan; bakteria Bacillus sp (PCR) dan Bacillus Pseudomycoides (BIOLOG) di dalam sampel kitaran enap cemar teraktif. Ketumpatan kuasa maksimum yang diperoleh daripada sampel kitaran enap cemar teraktif adalah 9.053 mW/cm2 dengan tahap penyingkiran COD dan jumlah nitrogen adalah (TKN) masing-masing 26.8% dan 40%
Penyediaan dan pencirian komposit Upr/Lnr/gentian kaca terawat menggunakan resin poliester tak tepu daripada bahan buangan pet
No full textKomposit UPR/LNR/gentian kaca telah disediakan dengan menggunakan resin poliester tak tepu daripada hasil pengitaran semula bahan buangan PET. Kajian dimulai dengan pengitaran semula botol minuman PET melalui proses glikolisis dan hasilnya ditindakbalaskan dengan maleik anhidrida untuk mendapatkan resin poliester tak tepu. Kajian diteruskan dengan penyediaan adunan resin poliester tak tepu (UPR) dengan cecair getah asli (LNR) iaitu komposisi penambahan LNR ke dalam UPR telah diubah dari 0-7.5% (wt). Komposisi UPR/LNR dengan sifat mekanik terbaik dipilih sebagai matrik untuk penyediaan komposit berpenguat gentian kaca. Rawatan silana ke atas gentian kaca turut dilakukan dengan menggunakan (3-Aminopropil)triethoxysilane. Hasil daripada kajian mendapati adunan UPR/LNR dengan penambahan 2.5% LNR mempunyai sifat mekanik dan morfologi terbaik dengan partikel-partikel getah yang bersaiz kecil dapat tersebar dengan sekata dalam UPR. Kajian juga menunjukkan berlakunya peningkatkan dalam nilai tegasan, modulus regangan dan kekuatan hentaman bagi komposit UPR/LNR/gentian kaca terawat berbanding dengan penggunaan gentian tanpa rawatan
Physico-chemical properties of the oils and fat from crotalaria cleomifolia seeds
No full textThe seeds of C. cleomifolia (locally known as kacang hantu) collected along Simpang Pulai - Berinchang Road, Cameron Highlands, was defatted with hexane and the resulting oil was analysed for their physico-chemical properties. The percentage yield of the oil was calculated as 5.3%. The acid value (1.2%), iodine value (85), peroxide value (0.6), saponification value (192.0) and unsaponifiable matter (2.3%) were determined to assess the quality of the oil. The physico-chemical characterisation showed that C. cleomifolia seeds oil is unsaturated semi-drying oil, with high saponifi cation and acidic values. The fatty acid composition of C. cleomifolia seed oil was determined by Gas Chromatography and Gas Chromatography-Mass Spectrometry (ToF). The seed oil of C. cleomifolia contained linoleic acid (57.59%) and palmitic acid (5.07%), the most abundant unsaturated and saturated fatty acids, respectively. The polyunsaturated triacylglycerol (TAG) in C. cleomifolia seed oil determined by reverse phase High performance Liquid Chromatography; contained as PLL (18.04%) followed by POL + SLL (11.92%), OOL (7.04%) and PLLn (6.31%). The melting and cooling point of the oil were 16.22°C and -33.54°C, respectively