In this study, the plasma characteristics and GaN etch properties of inductively coupled Cl2/Ar and Cl2/H2 plasmas were investigated. Our results showed that inductively coupled plasma (ICP) etching of gallium nitride by using Cl2/Ar and Cl2/H2 were possible to meet the requirements (anisotropy, high etch rate and high selectivity). We have investigated the etching rate dependency on the percentage of argon and hydrogen in the gas mixture and the DC voltage. Surface morphology of the etched samples was checked by SEM and AFM. It was found that the etched surface was anisotropic and the smoothness of the etched surface is comparable to that of polished wafer. As results, gas mixture using Cl2/Ar, we obtained highest etching rates; 5000 Å/min and ~0.5 nm rms roughness for n-GaN and for p-GaN, the etching rates was 3300 Å/min and ~0.7 nm for rms roughness. Meanwhile, for gas mixture using Cl2/H2, the etching was 1580 Å/min for n-GaN and 950 Å/min for p-GaN.
Due to their high ionic conductivity, solid polymer electrolyte (SPE) systems have attracted wide spread attention as the most appropriate choice to fabricate all-solid-state electrochemical devices, namely batteries, sensors and fuel cells. In this work, ion conductive polymer electrolyte membranes have been prepared for battery fabrication. However, fractals were found to grow in these polymer electrolyte membranes weeks after they were prepared. It was believed that the formation of fractal aggregates in these membranes were due to ionic movement. The discovery of fractal growth pattern can be used to understand the effects of such phenomenon in the polymer electrolyte membranes. Digital images of the fractal growth patterns were taken and a simulation model was developed based on the Brownian motion theory and a fractal dialect known as L-system. A computer coding has been designed to simulate and visualize the fractal growth.
MeSH terms: Attention; Electrolytes; Ions; Motion; Polymers; Electric Power Supplies; Fractals
A ZnO gas sensor was successfully prepared by RF sputtering. The maximum sensitivity of the sensor for vinegar test application was at 400oC. The ZnO based sensor showed good sensitivity for vinegar test in the concentration range of 4% to 9%. The work reveals the ability of using ZnO gas sensor to determine the acid concentrations of the vinegars for food requirements.
Polarized infrared (IR) reflectance spectrum studies of bulk wurtzite ZnO are presented. The features of the polarized IR reflectance spectra and the optical characteristics of ZnO were investigated. Based on the anisotropic dielectric function model, the experimental IR reflectance spectra were numerically fitted by the theoretical IR reflectance spectra. The obtained transverse optical (TO) and longitudinal optical (LO) frequencies, i.e., ωTO⊥(ωTO||) and ωLO⊥(ωLO|| ) are 411 cm-1 (384 cm-1) and 589.8 cm-1 (572 cm-1), respectively. These results are compared with the reported values measured from the other techniques. Good agreement has been obtained.
The transition of orthogonal smectic A (SmA) phase to the tilted phases, upon lowering the temperature, is explored with a discrete phenomenological model and the phase diagrams are presented. The results show that the transition of SmA to uniplanar structures can be affected by the effect of chirality. The areas showing the uniplanar phase in the phase diagrams diminish with the increase in effect of chirality.
This paper considers the problem of outlier detection in bilinear time series data with special focus on BL(1,0,1,1) and BL(1,1,1,1) models. In the previous study, the formulations of effect of innovational outlier on the observations and residuals from the process had been developed and the corresponding least squares estimator of outlier effect had been derived. Consequently, an outlier detection procedure employing bootstrap-based procedure to estimate the variance of the estimator had been proposed. In this paper, we proposed to use the mean absolute deviance and trimmed mean formula to estimate the variance to improve the performances of the procedure. Via simulation, we showed that the procedure based on the trimmed mean formula has successfully improved the performance of the procedure.
MeSH terms: Drug Compounding; Employment; Polymethacrylic Acids; Least-Squares Analysis
The nutrient composition, cooking characteristics and sensory properties of beef patties incorporated with various level of cornsilk were studied. The beef patties were formulated with either 2, 4 or 6% of cornsilk. Protein content increased in line with the cornsilk level in both raw and cooked beef patties. Both raw and cooked patties incorporated with 6% cornsilk recorded the highest protein concentration at 17.2 and 23.3%, respectively. Both raw and cooked patties containing 6% cornsilk recorded the lowest concentration of fat at 12.4 and 11.4%, respectively. All cooked patty samples recorded moisture content ranging from 40.42-42.98%. Beef patty formulated with 6% cornsilk recorded the highest cooking yield at 80.13% compared to other treatments. The addition of cornsilk did not change the sensory properties and consumer acceptability of cornsilk-based beef patties. Cornsilk fibre was effective in improving cooking yield, moisture and fat retention and enhancing texture of beef patties.
MeSH terms: Red Meat; Animals; Cattle; Cooking; Dietary Fiber
Kerang popular sebagai sumber protein dan mempunyai kepentingan ekonomi yang tinggi di Malaysia. Tujuan kajian ini adalah untuk menentukan komposisi protein, lemak dan abu serta mengenal pasti kandungan logam berat dalam tisu kerang yang diambil dari tapak-tapak ternakan di Kuala Juru (Pulau Pinang), Kuala Sepetang (Perak) dan Kuala Selangor (Selangor) untuk meneliti aras keselamatan logam berat dan kandungan zat nutrien dalam isi kerang. Kandungan protein, lemak dan abu dalam tisu kerang masing-masing adalah pada julat 70.0-75.6, 8.9-10.6 dan 9.8-17.5% berat kering. Untuk jumlah tenaga ialah 371.0, 384.2 dan 377.9 kcal/100 g berat kering kerang masing-masing untuk sampel dari Kuala Juru, Kuala Sepetang dan Kuala Selangor. Aras logam perlu dalam tisu kerang ialah Cu = 2.4-16.3, Fe = 421.0-1350.0, Mn = 10.0-38.1 dan Zn = 72.2-201.7 μg/g berat kering manakala kepekatan logam toksik adalah Cd = 1.3-12.2, Cr = 4.3-9.8, Ni = 8.3-20.8 dan Pb = 4.1-20.8 μg/g berat kering. Sebagai kesimpulan, didapati bahawa pengambilan harian sebanyak 1.50 g Pb (berat kering) kerang dari Kuala Sepetang dan juga melebihi 5.78 g Cd (berat kering) untuk kerang dari Kuala Selangor boleh meningkatkan risiko kesihatan.
Kajian ini dilakukan untuk menentukan ciri fiziko-kimia, kandungan nutrien dan logam berat dalam tanih di tapak Pusat Penyelidikan UKM Tasik Chini. Sampel tanih-atas diambil dari tiga transek pensampelan iaitu T1, T2 dan T3. Dua profil tanih telah dicerap di transek 1 (T1S1 & T1S3) dan sampel tanih telah diambil daripada profil dan juga tanih atas untuk penentuan ciri fiziko-kimia, kandungan nutrien dan logam berat. Bagi sampel tanih-atas, sebanyak empat stesen pensampelan (S1, S2, S3, S4) telah dipilih di transek 1 (T1), dua stesen pensampelan (S1, S2) di transek 2 (T2) dan tiga stesen pensampelan (S1, S2, S3) di transek 3 (T3) telah dipilih. Ciri fiziko-kimia yang ditentukan adalah pH, kekonduksian elektrik (KE), kapasiti pertukatan kation (KPK), fosforus, kalium dan magnesium tersedia dan nutrien terlarut, dan logam berat terpilih. Semua penentuan fiziko-kimia tanih, nutrien tersedia dan terlarut serta logam berat dilakukan mengikut kaedah penentuan yang piawai. Hasil uji kaji menunjukkan tekstur tanih didominasi oleh zarahan bersaiz lempung. Kandungan bahan organik tinggi pada tanih-atas dan berkurangan mengikut kedalaman. Purata nilai pH tanih di dalam profil dan tanih-atas adalah di antara 3.66 hingga 4.73 dan ia adalah sangat berasid. Sela purata bagi kekonduksian elektrik dalam profil dan tanih-atas adalah antara 2412 μScm-1 dan 2742 μScm-1. Purata nilai KPK adalah rendah iaitu antara 4.86 dan 12.58 meq/100g tanih. Kepekatan fosforus, magnesium dan kalium tersedia masing-masing mempunyai sela antara 1.76 – 3.32 μg/g, 16.80 – 122.23 μg/g dan 20.09 – 30.50 μg/g. Kepekatan nutrien terlarut bagi sulfat, nitrat-nitrogen, ammonium-nitrogen dan fosforus masing-masing adalah 37.50 – 1350 μg/g, 12.17 dan 90.00 μg/g, 12.17 to 53.17 μg/g dan 0.05 dan 0.62 μg/g. Kepekatan ferum dan Pb sangat tinggi di T1S1 dan di horizon bawah profil T1S3. Secara amnya tanih di tapak PPTC adalah sangat berasid dan mempunyai kandungan nutrien yang rendah. Terdapat bukti menunjukkan berlaku pengayaan Pb dalam tanih yang menerima pengaruh pasang surut jasad air tasik.
Titanium oxide (TiO2) nanotubes were successfully formed by anodization of pure titanium foil in a standard two-electrode bath consisting of ethylene glycol solution containing 5 wt% NH4F. The pH of the solution was ∼ 7 and the anodization voltage was 60 V. It was observed that such anodization condition results in ordered arrays of TiO2 nanotubes with smooth surface and a very high aspect ratio. It was observed that a minimum of 1 wt % water addition was required to form well ordered TiO2 nanotubes with length of approximately 18.5 μm. As-anodized sample, the self-organized TiO2 nanotubes have amorphous structure and annealing at 500oC of the nanotubes promote formation of anatase and rutile phase. Photocatalytic activity of well ordered TiO2 nanotubes with two different lengths was evaluated by measuring the degradation of methyl orange (MO). The elaboration of this observation is described in detail in this paper.
The main purpose of this study was to evaluate the level of knowledge, attitudes and practices among food handlers at residential colleges and canteen in the main campus of Universiti Kebangsaan Malaysia regarding the aspect of food hygiene and safety. Sixty five food handlers from two residential colleges’ cafeterias and one Faculty of Science and Technology’s canteen were involved in the study. The data were collected from the food handlers through the methods of questionnaire and analyzed using the SPSS version 12.0. In general, the respondents’ knowledge was moderate with mean point of 57.8%. However, they have good knowledge on personal hygiene and definition of foodborne diseases with mean point of 93.85% and 73.85%, respectively. On the contrary, their knowledge on food storage and preparation temperatures was poor with only 28%. Respondents showed positive attitudes towards two categories of questions in the aspect of food safety and hygiene (76.9%); foodborne prevention and control (70.8%). Majority of the respondents have an average practices in all parts of the questions. Analysis tests showed significant difference (p<0.05) between the relationship of respondents’ knowledge with their working experiences (p=0.008), attitudes with training attended (p=0.006) and practices with gender (p=0.032). There was significant difference for knowledge based on cafeteria (p=0.000). In conclusion, amongst the three levels, respondents showed only good attitudes in food handling and all the cafeterias in this survey need to increase the hygiene level of their food handlers’ hand and environment of the premises.
Stem cell is defined as the ability of the cell to proliferate themselves and differentiate into more than one type of cells. Human mononucleated cell (MN cell) is a suspension cell that was isolated from peripheral blood that was originated from monocyte-machrophage lineage or hematopoietic stem cells. The cells were cultured for 30 days in complete media (CM) which consist of Alpha Minimal Essential Medium (αMEM) with 2% (v/v) Penicillin-Streptomycin and 10% (v/v) Newborn Calf Serum (NBCS). The respective cells were differentiated at day 7 after in vitro proliferation in CM into osteoblastic cells by adding ascorbic acid and β-glycerophosphate. In addition, human recombinant Receptor Activator of Nuclear Factor-β Ligand (hrRANKL) and human recombinant Macrophage-Colony Stimulating Factor (hrM-CSF) were added to induce osteoclastic differentiation of MN cells. Cells that were cultured in CM served as a control and were subjected to the same approach as differentiated cells. The 30 days cultured cells in CM showed a significant increment (p < 0.05) of viable cells compared to day 0 (n=3). The specific activity of Alkaline Phosphatase (ALP) for osteoblast differentiation and Tartrate Resistant Acid Phosphatase (TRAP) for osteoclast differentiation were evaluated via biochemical assay until day 14 and day 10 for osteoblast and osteoclast sample, respectively. ALP and TRAP enzyme showed a significant increment (p < 0.05) after 14 and 10 days of differentiation compared to control cells. As a conclusion, human mononucleated cells are believed to have the potential to be defined as a multipotent stem cell based on their fulfillment of stem cell characteristics.
For testing the homogeneity of variances, modifications of well-known tests are known which combine rigorous theory with resampling (bootstrap). We propose versions of these tests, which are computationally simpler (although asymptotically equivalent). The earlier procedures used the smooth bootstrap with two thousand bootstrap replications per sample whereas our proposals use only the classical bootstrap (or percentile method) with just one thousand bootstrap replications per sample, and also required much less computing time. Our proposals cover the Ansari-Bradley-, Mood- and Klotz-tests. We explain their superiority over the existing methodologies available in textbooks and packages.
MeSH terms: DNA Replication; Muscle Rigidity; Chills
Nanozarah zink oksida telah disintesis menggunakan afrons gas koloid sebagai acuan. Zink sulfat (ZnSO4.7H2O) dan gas ammonia digunakan sebagi bahan tindak balas. Masa pengeraman yang dikaji adalah 2 jam dan 18 jam. Daripada analisis mikroskop elektron imbasan, morfologi nanohelaian dapat diperhatikan dengan ketebalan helaian 125 nm hingga 200 nm. Daripada analisis spektroskopi ultra lembayung-boleh nampak, saiz purata yang dianggarkan bagi sampel nanozarah zink oksida yang disintesis dengan masa pengeraman 2 jam adalah 2.03 nm dan 2.1 nm untuk sampel yang dieramkan selama 18 jam.
Satu kajian telah dijalankan untuk menguji kesan sitotoksik dan aktiviti antibakteria ekstrak metanol dari bahagian berbeza tumbuhan Phyllanthus gracilipes dan P. columnaris. Pengekstrakan dilakukan pada suhu bilik dan menggunakan alat-radas Soxhlet untuk menghasilkan 22 ekstrak. Ujian fitokimia ke atas ekstrak Soxhlet menunjukkan kehadiran saponin dalam semua ekstrak manakala steroid terdapat dalam ekstrak semua bahagian P. gracilipes dan 3 daripada ekstrak P. columnaris. Ujian sitotoksik ke atas kultur sel Vero menunjukkan hanya empat ekstrak yang sitotoksik dengan nilai LC50 di bawah 20 μg/mL iaitu ekstrak suhu bilik kulit-batang P. gracilipes, ekstrak Soxhlet kayu-batang dan daun P. gracilipes serta ekstrak suhu bilik kayu-akar P. columnaris. Ekstrak suhu bilik dan Soxhlet kayu-batang P. gracilipes serta semua ekstrak suhu bilik P. columnaris merencat pertumbuhan 13 pencilan Staphylococcus aureus Rintang-Metisillin (MRSA) yang diuji.
Parameter kekuatan ricih seperti sudut geseran permukaan ketakselanjaran batuan merupakan antara data penting bagi reka bentuk struktur kejuruteraan batuan seperti pengorekan bawah tanah dan cerun potongan. Ujian ricih terus beban normal tetap telah dilakukan pada permukaan buatan potongan gergaji batuan granit segar dan terluluhawa sedikit untuk menentukan sudut geseran asas permukaan satah ketakselanjaran. Sampel granit diperoleh dari Kuari Kajang Rock, Semenyih, Ulu Langat, Selangor, Lebuhraya Silk Kajang (km 14.6), Selangor, Jalan Pos Selim-Kampung Raja (km 30-29), Cameron Highland, Pahang/Perak dan Kuari JKR Bukit Penggorak, Kuantan, Pahang. Sebanyak 84 ujian ricih terus telah dijalankan pada batuan granit iaitu 65 ujian pada batuan segar dan 19 ujian pada batuan terluluhawa sedikit. Untuk batuan granit segar, sudut geseran asas ialah 42° ± 0.6° dengan sisihan piawai sebanyak 2.26 dan pekali penentuan, R2 sebanyak 0.98. Untuk granit terluluhawa sedikit, sudut geseran asas ialah 38° ± 1.9° dengan sisihan piawai sebanyak 3.99 dan pekali penentuan, R2 sebanyak 0.97. Nilai-nilai ini adalah lebih tinggi daripada nilai yang selalu dianggap untuk batuan granit segar iaitu 30°-35°.
Kajian 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 hingar.
In many statistical analyses, data need to be approximately normal or normally distributed. The Kolmogorov-Smirnov test, Anderson-Darling test, Cramer-von Mises test, and Shapiro-Wilk test are four statistical tests that are widely used for checking normality. One of the factors that influence these tests is the sample size. Given any test of normality mentioned, this study determined the sample sizes at which the tests would indicate that the data is not normal. The performance of the tests was evaluated under various spectrums of non-normal distributions and different sample sizes. The results showed that the Shapiro-Wilk test is the best normality test because this test rejects the null hypothesis of normality test at the smallest sample size compared to the other tests, for all levels of skewness and kurtosis of these distributions.
MeSH terms: Health; Normal Distribution; Sample Size; Statistics, Nonparametric
Sel osteoblas merupakan sel mononukleus yang bertanggungjawab untuk pembentukan tulang. Sel mononukleus telah terbukti mampu membeza kepada sel osteoblas setelah diaruh oleh kombinasi asid askorbik dan ß-gliserofosfat sebagai faktor pembezaan. Tujuan kajian ini adalah bagi melihat kesan aruhan ß-gliserofosfat terhadap ampaian sel mononukleus daripada darah periferi manusia secara in vitro. Sel mononukleus dipencilkan daripada darah periferi manusia dengan menggunakan larutan Ficoll-Paque™ Plus melalui kaedah pengemparan kecerunan ketumpatan. Sel mononukleus kemudian dikultur selama 7 hari di dalam medium proliferasi sebelum diaruh dengan ß-gliserofosfat pada kepekatan 1 mM, 5 mM, 10 mM, 20 mM, dan 100 mM. Pada hari 0, 1, 3, 7, dan 14, penentuan profil aktiviti enzim alkalin fosfatase (ALP) dan analisis morfologi bagi sel osteoblas dilakukan dalam medium masing-masing. Aktiviti enzim ALP dan analisis morfologi menunjukkan peningkatan yang signifikan (p<0.05) antara sel yang diaruh dengan sel kawalan negatif melalui statistik ujian-t berpasangan. Kesimpulannya, kehadiran ß-gliserofosfat sahaja mampu untuk mengaruh pembezaan sel mononukleus kepada sel osteoblas. Kesan ß-gliserofosfat terhadap pembezaan sel mononukleus kepada sel osteoblas menunjukkan profil enzimologi (aktiviti enzim ALP) dan morfologi yang hampir sama dengan kawalan positif (asid askorbik dan ß-gliserofosfat). Berdasarkan kepada analisis enzimologi dan morfologi 1 mM ß-gliserofosfat adalah kepekatan yang paling sesuai untuk pembezaan sel osteoblas secara in vitro.
Eimeria tenella merupakan salah satu daripada tujuh spesies Eimeria yang menjangkiti ayam. Jangkitan parasit ini menyebabkan penyakit koksidiosis yang mendatangkan kerugian ekonomi yang besar kepada industri penternakan ayam. Adalah dipercayai parasit yang terdapat di dalam ayam domestik berasal daripada dan/atau mempunyai kaitan rapat dengan strain yang wujud di dalam ayam hutan. Oleh yang demikian, pencirian spesies Eimeria ini yang dipencil daripada ayam hutan tempatan akan memberi pengetahuan baru bagi meningkatkan pemahaman mengenai biologi parasit ini. Dalam kajian yang dilaporkan di sini, populasi parasit Eimeria AH1 telah dipencil daripada saluran usus ayam hutan tempatan. Berasaskan kepada pasaj bersiri didapati penghasilan oosista populasi AH1 tersebut dalam ayam domestik bergantung kepada umur oosista dan dos jangkitan. Pencirian morfologi pula menunjukkan oosista populasi AH1 berbentuk ovoid dan kebanyakan oosista tersebut mempunyai granul kutub. Nilai dimensi purata bagi oosista populasi AH1 ialah 22.51 (± 0.17) × 17.30 (± 0.14) μm. Saiz oosista populasi AH1 didapati berbeza secara signifikan (p < 0.05) berbanding dengan saiz oosista strain rujukan, E. tenella strain Houghton. Amplifikasi tindak balas berantai polimerase multipleks populasi AH1 menghasilkan jalur bersaiz ~540 pb yang berkolerasi dengan saiz produk yang spesifik untuk E. tenella. Hasil kajian kami ini mengesahkan bahawa populasi Eimeria AH1 yang dipencilkan daripada ayam hutan tempatan, terdiri daripada parasit E. tenella.