Effects of radiation on free convection about a heated horizontal circular cylinder in the presence of heat generation is investigated numerically. The cylinder is fixed and immersed in a stationary fluid, in which the temperature is uniformly heated about the temperature of the surrounding fluid. The governing equations are transformed into dimensionless non-linear partial differential equations and solved by employing a finite difference method. An implicit finite difference scheme of Crank Nicolson method is used to analyze the results. This study determined the effects of radiation parameter, heat generation parameter, and the Prandtl number, on the temperature and velocity profiles. The results of the local heat transfer and skin-friction coefficient in the presence of radiation for some selected values of and are shown graphically.
Gambar rajah fasa pseudo-ternari sistem mikroemulsi asid oleik/Cremophor rh 40/Transcutol/Air diperoleh melalui pentitratan air pada nisbah surfaktan:kosurfaktan (Km) yang berbeza. Nisbah optimum bagi surfaktan/kosurfaktan adalah Km=2:1. Kesan penambahan limonena sebagai fasa minyak campuran terhadap sistem mikroemulsi diuji pada nisbah limonena:asid oleik (1:1, 2:1 dan 3:1). Penambahan limonena berupaya menghasilkan rantau mikroemulsi yang lebih besar sehingga 70%-80 % bt. air bagi kesemua nisbah limonena:asid oleik. Nisbah limonena:asid oleik (1:1) memberikan rantau mikroemulsi yang paling luas pada nisbah minyak:surfaktan/kosurfaktan (Minyak:S/KoS=1:9). Sifat isotropik mikroemulsi ditentukan dengan menggunakan mikroskopi cahaya polarasi. Mikroemulsi dibangunkan pada nisbah Km=2:1 dan Minyak:S/KoS (1:9) serta limonena:asid oleik (1:1). Kestabilan dan saiz partikel bagi sistem dikaji dan penambahan limonena didapati tidak merubah sifat serta mikro-struktur sistem mikroemulsi. Kajian konduktiviti elektrik dan kelikatan sistem menunjukkan pembentukan mikroemulsi jenis air-dalam-minyak (10% dan 20 % bt. air) dan dwiselanjar (30%-50 % bt. air). Kesemua sistem mempunyai potensi sebagai sistem penghantar bahan aktif dan menunjukkan kestabilan yang baik pada suhu 4, 25 dan 37°C dalam tempoh lebih daripada 6 bulan.
The first aim of this study was to determine the refractive error and visual acuity of Chinese elderly age 60 and above in Selangor and Johor, Malaysia. The second aim was to determine the percentage of elderly with vision impairment. Participants of this study were from the on-going population-based longitudinal study on neuroprotective model for healthy longevity (TUA) among Malaysian older adults using multistage random sampling. A total of 259 Chinese elderly aged 60 and above from state of Selangor and Johor agreed to participate. Refractive error was determined using autorefractometer Retinomax K-plus followed by subjective refraction. Best corrected visual acuity (VA) was measured using logMAR chart. Analysis was performed on data of 202 participants and the remaining 57 were excluded. Overall percentage of refractive error was higher for hyperopia (54%) compared to myopia (23.2%). High percentage of astigmatism was noted for all age groups (> 50%). Both gender showed similar distribution of refractive status. Mean overall VA was 0.24 ± 0.17 logMAR (≅ 6/9-) and mean VA declined with age. Overall, the percentage of elderly having at least mild vision impairment (> 0.3 logMAR or 6/12) was higher (62.9%) compared to normal vision (≤ 0.3 logMAR). However, percentage of vision impairment (VI) was highest in the mild category compared to others and only one participant had severe VI. This study found a high percentage of Chinese elderly with refractive error. The most common type of refractive error was hyperopia. A high proportion of them had mild vision impairment followed by moderate VI even with best correction. Vision impairment could affect daily life functioning and this effect can be further explored in the future.
The molecular characteristics of sago starch (native and debranched) were determined using a gel permeation chromatograpy multi-angle laser light scattering (GPC-MALLS) method. The method involves the optimisation of sample solubilisation and GPC operating conditions. The weight-average molecular weight Mw of native and debranched sago starch determined was 29.1 ± 2.1 × 106 and 1.87 ± 0.4 × 105 gmol-1 respectively while radius of gyration Rg was 123.6 and 59.3 nm respectively. The reduction in Mw and Rg in debranched sago was attributed to the hydrolysis of α-1,6 glycosidic linkages by pullulanase to smaller oligosaccharides.
In this paper a class of capital investment problem is considered within the context of mathematical programming. The usual and commonly used approach is presented upon the basis of the next present value criterion, and a branch and bound method is discussed for a model under extended assumptions.
Dalam kertas ini satu kelas masalah pelaburan kapital difikirkan di dalam konteks pengaturcaraan matematik. Pendekatan biasa dan selalu digunakan, dikemukakan berasaskan kriterium Nilai Semasa Berikut dan satu kaedah bercabang dan terbatas dibincangkan untuk satu model di bawah anggapan yang diperluaskan.
Allicin or diallyl thiosulfinate (C3H5SS(O)C3H5), an active compound of garlic (Allium sativum) is known for its pharmaceutical properties. In this study, the cellular destructive effects of allicin on a haemoflagellate protozoa parasite Trypanosoma evansi was investigated. Groups of male ICR mice were infected with a lethal dose of the parasite (1×105 parasites per mouse) and each group was either treated intraperitoneally with berenil (0.01 mL per mouse, a commercial anti-trypanosomal drug) on D+3 post-infection as the positive control group, treated orally with allicin (0.1 mL of 15 μg/mL allicin solution per mouse) for 30 days starting from D-7 pre-infection as the experimental group, or left untreated as the negative control group. Thin-stained blood smears were prepared from each mouse every alternate day, starting from D+3 post-infection and continued until the animal succumbed or until D+90 post-infection. Parasitaemias were determined using light microscope. Unstained blood smears were also prepared for direct observation under Phillips XL30 and Leo 1450VP scanning electron microscopes. All mice in the negative group succumbed to the infection with drastic increase of parasitaemias while all the positive control mice had minimal parasitaemias and cleared from the infection and survived for more than 100 days. On the other hand mice in the experimental group, experienced a prolonged suppressed parasitaemias which became patent later and caused death to all mice. Micrograph observations of parasites in the positive group showed that the parasites had adverse morphological changes due to berenil treatment which lead to cell destruction and death within 5 – 6 hours post-treatment. Likewise parasites in the experimental group too had undergone profound physical damages which caused cell death. This is the first report which shows that allicin actually induced cellular damage to haemoflagellate cells of T. evansi in vivo.
Kertas kerja ini membincangkan pendekatan dalam mengintegrasikan Java dan persekitaran VRML yang telah diaplikasikan dalam mensimulasi masa nyata bagi proses kisar hujung maya. Pendekatan yang menggunakan Routing ini adalah sangat penting untuk komunikasi dan penghantaran mesej antara VRML dan Java. Dalam pendekatan ini, nod Script digunakan bagi memanggil dan menghubungkan kelas Java dengan entiti-entiti yang sepatutnya di dalam persekitaran VRML. Simulasi bahan termesin bagi proses kisar hujung dalam sistem ini dilaksanakan melalui satu kaedah baru iaitu dengan penggunaan nod penaikan bagi penjanaan objek 3D dan nod PositionInterpolator serta CoordinateInterpolator bagi animasi bahan termesin. Melalui kaedah ini simulasi bagi proses kisar hujung dapat dipaparkan secara maya dan pada masa yang sama graf haus rusuk bagi perkakas pemotong melawan masa pemotongan dapat dijana serentak.
In this work, the emission efficiency of InxGa1-xN based light emitting diodes (LEDs) had been numerically investigated with the variation of the number of quantum well. From our calculation, we found that non-uniformity of carriers distribution (especially electron) in the wells leads to serious inhomogeneity of radiative recombination distribution that would degrade the efficiency of the LED with more wells. However, the problem was minimized when the selected quantum barriers were doped with a reasonable doping level. Comparison with other reported experimental works were also included. At the end of this work, we proposed several types of preferable LEDs designs with optimum structural parameters.
In this work, epoxidized natural rubber 50 (ENR-50) has been used as a host polymer for the preparation of electrolyte system. Attenuated total reflection-fourier transform infrared spectroscopic analyses showed the presence of lithium saltENR interactions. The glass transition temperature displayed an increasing trend with the increase in salt concentration indicating that the ionic conductivity was not influenced by segmental motion of the ENR-50 chains. The increase in
glass transition temperature with the addition of salt was due to the formation of transient cross-linking between ENR-50 chains via the coordinated interaction between ENR-50 chains and salt. The highest room temperature ionic conductivity obtained was in the order of 10-5 S cm-1 for the film containing 50 wt% of lithium salt. The ionic conductivity of this electrolyte system increased with increasing temperature and obeyed the Vogel-Tamman-Fulcher behavior. The increase in ionic conductivity of the electrolyte system with salt concentration could also be correlated to the charge carriers concentration and/or migration rate of charge carriers.
Several conventional staining techniques were employed to detect the life stages (in particular the spores) of Nosema bombycis from infected larvae of Plutella xylostella (diamondback moth, DBM) and the effects of the infection of N. bombycis on the larvae were studied. Larval instars 1, 2, 3 and 4 of the DBM were infected with four different spore concentrations (407150, 41420, 4260 and 420 spores/μl) accordingly by allowing them to feed on artificial diet previously inoculated with the respective spore concentrations. Larval tissues were processed for staining and the number of spores were counted and direct observations on the larvae were carried out at 24, 48 and 72 h post infection. The Gram s, Giemsa's, haematoxylin and trichrome staining techniques were more superior in detecting the spores, sporonts and meronts than the good Pasteurs. The main effect of the infection was mortality which was dose-dependent and that the younger ins tars were more susceptible to infection than the older ones. Spore concentrations of 407150, 41420 and 4260 spores/μl) caused death to the instars whereas the dose of 420 spores)μl was unable to kill the larval instars. The mortality rate of the younger instars was significantly higher (p<0.001) than the older ones. The LC50 and LC95 values of instar 1 and 2 were lower than those of the instar 3 and 4 after 48 and 72 h post infection. This showed that high spore concentrations were needed to kill the bigger size and matured instars. Histological studies on the infected larvae indicated that the infection caused severe cellular damages in fat tissues and the intestine leading to death. Results of this studies showed that life stages of N. bombycis in particular the spores were detected effectively using conventional staining techniques and the infectivity and the effects of the infection on the larval tissues of DBM were also established.
[Beberapa teknik pewarnaan biasa telah digunakan untuk mengesan peringkat hidup Nosema bombycis (khususnya spora) yang terdapat pada larva Plutella xylostella (rama-rama belakang intan, DBM) yang terjangkit begitujuga kesan jangkitan spora ini ke atas larva telah dikaji. Larva instar 1,2,3 dan 4 DBM yang bebas daripadajangkitan spora telah dijangkiti dengan empat kepekatan spora (407150, 41420, 4260 dan 420 spora/μl) secara berasingan dengan membiarkan larva ini memakan makanan buatan yang telah dicemari dengan kepekatan spora tersebut. Pemprosesan tisu dengan teknik pewarnaan, penentuan kepekatan spora daripada larva dan cerapan langsung telah dilakukan dalam tempoh 24, 48 dan 72 j selepas jangkitan. Didapati teknik pewarnaan Gram, Giemsa, hematoksilin dan trikrom lebih sesuai untuk mengesan spora, sporon dan meron daripada tisu larva yang terjangkit berbanding teknik 'good Pasteur'. Kesan utama jangkitan spora ialah kematian larva yang bergantung kepada kepekatan spora yang digunakan dan didapati ins tar yang lebih muda adalah lebih rentan terhadap jangkitan ini berbanding instar yang lebih matang. Kepekatan spora 407150, 41420 dan 4260 spora) μl boleh menyebabkan kematian manakala kepekatan spora terendah (420 spora/)1.l) tidak menyebabkan kematian. Kadar kematian instar yang lebih muda lebih tinggi (p<0.001 ) berbanding instar yang lebih matang. Nilai LC50 dan LC95 bagi instar 1 dan 2 lebih rendah berbanding instar 3 dan 4, selepas 48 dan 72 j jangkitan. lni menunjukkan bahawa kepekatan spora yang lebih tinggi diperlukan untuk membunuh instar yang bersaiz lebih besar dan lebih matang. Bilangan spora terendah diperolehi pada tempohjangkitan 24 j manakala bilangan spora tertinggi diperolehi pada tempoh jangkitan 72 j. Kajian histologi ke atas tisu larva terjangkit mendapati kerosakan terjadi pada tisu lemak dan usus yang menyebabkan kematian. Hasil kajian ini menunjukkan bahawa peringkat hidup N bombycis khususnya spora dapat dikesan dengan baik menerusi teknik pewarnaan yang biasa dan kebolehjangkitan parasit ini dan kesannya kepada larva DBM telah diketahui].
Ficus deltoidea is one of the common medicinal plants used in Malaysia. This epiphytic plant, from the Moraceae family has been claimed to have antidiabetic property. However, scientific evidence to confirm its efficacy is still lacking. The present study was undertaken to evaluate the effect of ethanolic extract of F. deltoidea on glucose level in normal rats at different prandial state. The results showed that, all doses of ethanolic extract of F. deltoidea reduced fasting blood glucose particularly after 6 h of administration. Interestingly, the extract did not produce severe hypoglycemia as shown by its comparable effect with metformin. Likewise, postprandial hyperglycemia was also significantly reduced particularly after 4 and 6 h of administration. Furthermore, extract was used at a dose of 1000 mg/kg b.w., reduced postprandial hyperglycemia similar to metformin. This suggests that postprandial antihyperglycemic mechanism of this extract is mediated through enhancement of glucose uptake into muscle cells and reduction of hepatic gluconeogenesis. Glucose tolerance activity was also significantly improved in the presence of ethanolic extract of F. deltoidea. From this study, it is suggested that ethanolic extract of F. deltoidea reduced postprandial hyperglycemia and improves glucose tolerance activity in normal rats.
Fossil fuels (petroleum, natural gas and coal) are the main resources for generating electricity. However, they have been major contributors to environmental problems. One potential alternative to explore is the use of microbial fuel cells (MFCs), which generate electricity using microorganisms. MFCs uses catalytic reactions activated by microorganisms to convert energy preserved in the chemical bonds between organic molecules into electrical energy. MFC has the ability to generate electricity during the wastewater treatment process while simultaneously treating the pollutants. This study investigated the potential of using different types of mixed cultures (raw sewage, mixed liquor from the aeration tank & return waste activated sludge) from an activated sludge treatment plant in MFCs for electricity generation and pollutant removals (COD & total kjeldahl nitrogen, TKN). The MFC in this study was designed as a dual-chambered system, in which the chambers were separated by a NafionTM membrane using a mixed culture of wastewater as a biocatalyst. The maximum power density generated using activated sludge was 9.053 mW/cm2, with 26.8% COD removal and 40% TKN removal. It is demonstrated that MFC offers great potential to optimize power generation using mixed cultures of wastewater.
Kajian 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%.
An efficient analytical technique capable of analyzing three most common phosphodiesterase-5 (PDE5) inhibitors (vardenafil, sildenafil and tadalafil) simultaneously in premix coffee was developed. Sample extractions using either acetonitrile or methanol with two different extraction techniques (with and without evaporation steps) were evaluated. Identification and quantitation was conducted by high performance liquid chromatography with photo-diode-array (HPLC-DAD) at different wavelengths; 230 nm, 245 nm and 290 nm; and by time of flight mass spectrometry (LC-MS-TOF). Extraction with acetonitrile (without evaporation with nitrogen) showed recovery ranging from 105% to 113% (± <10%) for HPLC-DAD at 245 nm and 93% to 102% (± <2.5%) for LC-MS-TOF. Chromatogram separation was best achieved with mobile phase consisted of water (0.1% formic acid) and acetonitrile (0.1% formic acid) with gradient elution within 20 min. Thus, the results indicated that extraction using acetonitrile without evaporation step was the most efficient technique for determination of PDE5 inhibitors in premix coffee.
The bulking treatment with phenolic resin is well known as a treatment to improve the properties of low density wood but high amount of formaldehyde emission will be released during and after treatment. A study was conducted to determine the performance of phenolic resin treated sesenduk (Endospermum diadenum) wood post treated with ammonium carbonate and urea. Wood strips were treated separately with 30% low molecular weight phenol formaldehyde resin (LmwPF) resin and mixture of LmwPF with urea (30% based on solid PF) using empty-cell process. Two products were produced from the treatment, i.e. impreg and compreg. After conditioning, the surfaces of the samples were applied with ammonium carbonate solution at 10, 20 and 30 g/m2 . The samples were then stacked and stored at 60°C for 48 h. Properties such as formaldehyde emission, strength and dimensional stability were evaluated. The results showed that the post treatment with ammonium carbonate has successfully reduced the formaldehyde emission from the sesenduk wood. The degree of reduction was depended on the amount of ammonium carbonate applied on the samples. The results also showed that the sesenduk wood treated with mixture of PF and urea had lower formaldehyde emission. Post treatment with ammonium carbonate did not significantly affect the physical and mechanical properties of the sesenduk wood.
The aim of the study was to develop response surface methodology (RSM) models for polymer loading, density, dimensional stability, strength and stiffness of compressed wood of sesenduk (Endospermum diadenum) treated with phenol formaldehyde (PF). Central composite design (CCD) using RSM with three processing parameters was studied in their specific ranges: PF concentration (PC) from 24-40%, pre-curing time (PCT), 3-9 h and compression ratio (CR), 70-90%. The experimental design was analysed and interpreted using the Design Expert Software (Stat Ease version 8) and the responses of 3d plots were built using the same software. Quadratic models in terms of PC, PCT and CR were developed for polymer loading, density, reduction in water absorption and modulus of rupture in static bending. Multiple linear equations were developed for anti-swelling efficiency and modulus of elasticity. The experimental values were in good agreement with predicted ones and the models were highly significant with correlation coefficients between 0.626 and 0.926. PC and CR had significant effects on the responses. The range of PCT used did not significantly affect the responses. It was also found that the improvement of properties ranged from moderately to highly correlated with the polymer loading in the compreg wood.
Kajian yang dijalankan ini bertujuan untuk melihat impak pengenalan instrumen derivatif ke atas kemeruapan pulangan saham di pasaran semerta. Kajian ini juga mengambil kira kesemua instrumen derivatif yang telah diperkenalkan di pasaran tempatan. Data harian bagi indeks komposit dan sebilangan indeks-indeks untuk setiap sektor akan digunakan di dalam kajian ini bagi mengkaji kesan secara keseluruhan dan mengikut sektor. Dengan menggunakan model GARCH terubahsuai iaitu dengan mengambil kira kesan perubahan struktur. Kajian ini mendapati wujudnya kesan yang bercampur-campur. Secara umumnya, pengenalan instrumen derivative mampu untuk mengurangkan tahap kemeruapan pulangan dan secara langsung menstabilkan pasaran saham. Tambahan pula, ia turut mempertingkatkan lagi kadar dan kualiti aliran maklumat ke dalam pasaran dan dengan demikian menjadikan pasaran saham bertambah efisien.
The study was conducted at Merambong Shoal (01°19.979’N, 103°35.965’E) in the Sungai Pulai estuary, Johor Straits, Malaysia from January to December 2005. Standing biomass of male and female Strombus canarium sub populations was calculated monthly based on the abundance value of each cohort and on the length-weight relationship. Secondary production was estimated using increment summation method, upon recognition of cohorts following the size-frequency distribution analysis using Bhattacharya and Hasselblad’s NORMSEP methods. Monthly variations in standing biomass
(B) and production (P) showed higher values during the wet season compared to dry season, which indicate seasonal variations. Total production (P) was estimated at 0.14 gAFDWm-2yr-1 and 0.45 gAFDWm-2yr-1, while the annual mean population biomass was estimated at 0.13 gAFDWm-2 and 0.26 gAFDWm-2, for males and females, respectively. The P/ ratio was therefore calculated at 1.08 yr-1 for male and 1.73 yr-1 for female, which was within the values reported for other gastropod species. Estimates using empirical methods commonly used in secondary production studies found
that none could be applied to the species. Considering the large amount of time, effort and resources involved in the conventional production estimation method, more studies are needed to establish a reliable production estimates for S. canarium, and possibly other gastropod species within the tropical region.
A total of 230 individuals of Strombus were sampled at various locations along the Johor Straits, Malaysia. There were four species of Strombus present in the study areas i.e. Strombus canarium Linnaeus, 1758; Strombus urceus Linnaeus, 1758; Strombus marginatus subspecies succinctus Linnaeus, 1767; Strombus marginatus subspecies robustus Sowerby, 1874; and Strombus vittatus subspecies vittatus Linnaeus, 1758. Strombus canarium was the most common, widely distributed and most abundant, followed by S. urceus, while the others were only rarely found. Among the species Strombus marginatus and Strombus vittatus were two new distribution records for the Johor Straits. Since all Strombus were traditionally harvested and consumed by the locals since long ago, further studies are needed particularly regarding the population dynamics and fishery of the harvested species.
The abundance of marine benthic organisms often exhibits distinct distributional patterns, which is generally governed by many physical and biological factors specific to the habitat. In this study, the spatial and temporal variations in abundance of the dog conch, Strombus canarium Linnaeus 1758, a commercially important marine gastropod, was investigated. Assessment of conch abundance at Merambong seagrass bed, Malaysia, was conducted using a transect belt method. Sampling stations were randomly selected and environmental parameters associated with the habitat were recorded. The species showed distinct spatial distributional pattern. Conch densities were significantly higher in sheltered areas, mainly in mixed seagrass bed dominated by Halophila spp. and with high sediment organic content. The densities were relatively very low in areas dominated by the tape seagrass, Enhalus acoroides. The species studied also showed distinct temporal variation in abundance. The abundance value was seasonally varied with highest density recorded during the wet monsoon season (p<0.05). The densities were otherwise very low during the dry season, except for a slight peak in July. Since the conch is a very important fishery species within the Johor Straits and regulations on their harvesting is still lacking, this information would be very important for their sustainable management.