Positron Emission Tomography-Computed Tomography (PET-CT) was introduced over four decades ago as an imaging tool to evaluate functional and anatomical aspects of disease such as malignancy. Besides pathological uptake, PET-CT also shows physiological uptake, especially in the gastrointestinal system, thus impacting diagnostic accuracy in these cases. There are many conditions that can attribute to increasing physiological uptake in PET-CT including microbial activity and drugs. Therefore, certain anti-spasmodic agents have been introduced to help reduce physiological uptake during scanning such as Hyoscine-n-butylbromide (Buscopan). This study aims to establish its effectiveness in reducing physiological bowel uptake on 18F-FDG PET-CT scan. Methods: 133 subjects were recruited in random for this study and divided into hyoscine (68 subjects) and control groups (65 subjects), respectively. Subjects in control group not given any anti-spasmodic medications and both groups received intravenous 18F-FDG according to body weight. PET-CT scan and images were interpreted by experienced nuclear medicine physician who scored the images according to the degree of bowel uptake and difficulty of image interpretation. Results: There were no statistical difference in bowel uptake based on SUV mean of the bowel and bowel-to-liver ratio between hyoscine and control groups. Conclusion: There was no significant effect of Hyoscine-n-butylbromide in reducing physiological bowel uptake in PET-CT scan.
Blends of fibre-reinforced rubber based on natural rubber-thermoplastic (NR/LLDPE) reinforced by aramid fibre have been done using melt blending process. Two different processing methods were used; internal mixer and extrusion compounding in twin screw extruder. Twaron loading in the system was varied from 0 to 30%. It was found that increasing the amount of aramid fibre led to an increase in the tensile strength, tensile modulus and hardness of the composites while the strain decreased rapidly. The results showed that the optimum composition of filler loading in NR/LLDPE blend is 20%. The ,echanical behaviour was caused by the strong Twaron-matrices interaction in the composites and effective stress concentrating function of Twaron. Composites prepared using the twin-screw extruder have a higher tensile strength and tensile using the twin-screw extruder have a higher tensile stength and tensile modulus but lower impact strength compared to those prepared using internal mixer. Study of the fracture surface by scanning electron microscopy showed that the composite prepared using the internal mixer produced random fiber orientation while the twin-screw extruder produced the fibers aligned to the longitudinal direction. The results indicate that the mechanical properties of the composite were significantly influenced by the processing technique.
Penyediaan komposit getah asli termoplastik daripada NR/LLDPE yang diperkuat gentian Twaron telah dijalankan melalui proses adunan leburan. Dua kaedah penyediaan yang berbeza digunakan iaitu menggunakan mesin pencampur dalaman manakala kaedah kedua menggunakan pengekstrud skru kembar. Kandungan Twaron di dalam komposit telah diubah daripada 0 hingga 30%. Keputusan menunjukkan bahawa penambahan Twaron telah meningkatkan nilai tegasan maksima, modulus Young dan kekuatan hentaman komposit tetapi menurunkan nilai terikan maksima. Kandungan Twaron yang optimum adalah 20%. Kehadiran Twaron telah membentuk satu jaringan saling tindak gentian-matriks menyebabkan kekuatan regangan komposit meningkat. Twaron juga berfungsi sebagai penyerap hentaman yang berkesan. Penyediaan komposit menggunakan pengekstrud skru berkembar telah menghasilkan nilai kekuatan regangan yang lebih tinggi berbanding penggunaan pencampur dalaman sebaliknya kekuatan hentaman yang lebih rendah. Kajian morfologi menggunakan mikroskop imbasan elektron mendapati komposit yang disediakan menggunakan pencampur dalaman menghasilkan gentian dengan orientasi rawak manakala pengekstrud skru kembar menghasilkan orientasi gentian yang selari. Keputusan ini menunjukkan bahawa sifat mekanik komposit NR/LLDPE yang diperkuat Twaron sangat dipengaruhi oleh teknik pemprosesan.
Concentration of Ra-226 and Ra-228 activities in water and sediment samples were measured using the Liquid Scintillation Counter (LSC) and High Purity Germanium Gamma Spectrometry (HPGe). respectively. Concentrations of Ra-226 activity in sediment samples range from 18.93 Bg/ kg to 236.06 Bq/kg and for Ra-228 activity range from 12.59 Bg/kg to 410.60 Bq/kg. Meanwhile, concentrations of Ra-226 activity obtained in water samples range from 0.064 Bg/L to 0.199 Bq/L. These data indicate, that the distribution of Ra-228 and Ra-226 in the study area were varied from one sampling stations to another and is probably related to the contents of suspended particles.
Penentuan kepekatan aktiviti Ra-226 dan Ra-228 dalam sampel air dan sedimen dilakukan masing-masing dengan Pembilang Sintilasi Cecair (LSC) dan Spektrometri Gamma Germanium Lampau Tulen (HPGe). Kepekatan aktiviti Ra-226 dalam sampel sedimen adalah berjulat dari 18.93 Bg/kg hingga 236.06 Bq/kg dan kepekatan aktiviti Ra-228 berjulat dari 12.59 Bg/kg hingga 410.60 Bq/kg. Kepekatan aktiviti Ra-226 dalam sampel air yang diperolehi pula berjulat dari 0.064 Bg/L hingga 0.199 Bq/L. Ini menunjukkan taburan Ra-228 dan Ra-226 di kawasan kajian adalah berubah mengikut lokasi kajian dan berkemungkinan dipengaruhi oleh sifat kandungan bahan terampai.
A study on the design of solid-state ion sensor was carried out. The electrode used was based on Ag/AgCl and two types of Ag/AgCl electrode designs used were rod-shape and screen printed (SPE) Ag/AgCl electrodes. The assessment of the electrode response was based on anion response, especially the response of chloride ions. Apart from that, the solid-state electrodes were also assessed for their response to several cations after a photocured polymer membrane with an immobilised lipophilic salt sensitive to cations was deposited on the electrodes. The results show that the use of a poly(hydroxyl ethyl methacrylate) hydrated with a salt solution is important to replace the inner reference solution of a conventional non solid-state ionÂ-selective electrode if normal response of an electrode is to be obtained. The sensor response which remains near to Nernstian after undergoing membrane deposition processes by photocuring technique indicate that these solid-state ion sensors can be used for the construction of biosensors that are based on potentiometric transduction.
Kajian rekabentuk sensor ion jenis keadaan-pepejal telah dilakukan. Elektrod yang digunakan adalah berdasarkan kepada Ag/AgCl. Rekabentuk dua jenis elektrod keadaan pepejal telah dipilih, iaitu berdasarkan elektrod Ag/AgCl jenis rod dan jenis elektrod Ag/AgCl bercetak skrin (screen printed electrode, SPE). Penilaian termasuk kajian responsnya terhadap anion, khasnya ion klorida. Di samping itu, respons elektrod keadaan-pepejal ini terhadap beberapa kation juga dilakukan setelah elektrod rod dan SPE disalutkan dengan beberapa jenis fotopolimer serta pemegunan garam lipofilik yang peka kepada kation. Hasil kajian menunjukkan penggunaan poli(hidroksi etil metakrilat) terhidrat dengan larutan garam untuk menggantikan larutan rujukan dalaman bagi elektrod pemilih ion konvensional yang bukan berbentuk keadaan-pepejal adalah penting demi menghasilkan sensor berbentuk keadaan pepejal yang bersifat normal. Ciri sensor ion yang masih bersifat hampir Nernstian walaupun telah mengalami beberapa proses fabrikasi sistem fotopolimer menunjukkan bahawa sensor keadaan-pepejal ini boleh juga digunakan dalam rekabentuk biosensor potentiometrik selain daripada sensor ion.
Electron beam vulcanization of natural rubber latex has been developed as an alternative to the conventional sulphur vulcanization method. This study aimed at determining the effect of electron beam dose, beam current and centrifugation to the tensile properties of field natural rubber latex. Irradiation dose and beam current ranged from 50 to 300 kGy and 1 to 15 mA respectively. The determination of tensile properties were done on cast film prepared from irradiated field latex before and after centrifugation. It was found that tensile properties increased with radiation dose but decreased with beam current. Rubber films made from centrifuged irradiated field latex were softer and showed higher tensile strength.
Peningkatan aktiviti perbandaran dan perindustrian telah mencetuskan masalah pengurusan sisa pepejal. Sebagai usaha penyelesaian, pendekatan bersepadu telah dipilih bagi menguruskan sisa pepejal. Membangunkan dan melaksanakan rancangan pengurusan sisa pepejal bersepadu perlu melibatkan gabungan teknologi dan pilihan yang sesuai dengan keadaan dan undang-undang tempatan. Kajian ini menunjukkan Proses Analisis Hierarki (PAH) berpotensi sebagai kaedah membuat keputusan yang boleh digunakan dalam proses pemilihan teknologi pengurusan sisa pepejal. Tiga aras hierarki dibangunkan dengan matlamat di aras tertinggi, diikuti oleh kriteria dan alternatif. Dengan menggunakan teknik ini, penentuan keutamaan untuk semua teknologi pengurusan sisa pepejal yang dipertimbangkan akan ditentukan dan teknologi dengan nilai keutamaan tertinggi lebih sesuai untuk dibangunkan. Analisis sensitiviti dilakukan bagi menguji sensitiviti keputusan akhir terhadap perubahan kecil penilaian. Aplikasi PAH dalam menentukan keutamaan proses pemilihan teknologi pengurusan sisa pepejal diperjelaskan dalam kajian ini berdasarkan kepada kajian kes di Majlis Perbandaran Port Dickson. Hasil analisis menunjukkan kombinasi teknologi kitar semula dan pengkomposan sesuai diaplikasikan di daerah Port Dickson.
Serbuk sekam padi (SP) merupakan serabut semula jadi yang boleh bertindak sebagai pengisi penguat dalam adunan getah asli termoplastik (TPNR) NR/HDPE selepas permukaan serbuk dimodifikasikan sewajarnya. Rawatan serbuk SP merangkumi pra-rawatan dengan 5% larutan natrium hidroksida (NaOH), rendaman dalam larutan getah asli cecair (LNR) dan dedahan SP tersalut LNR kepada sinaran electron (EB). Komposit TPNR/SP disediakan secara pengadunan leburan dalam pengadun dalaman pada keadaan yang telah ditentupastikan terlebih dahulu. Morfologi komposit yang dianalisis menggunakan mikroskop elektron imbasan (SEM), menunjukkan taburan zarah pengisi SP termodifikasi adalah homogen dan kewujudan interaksi matriks-zarah. Komposit terisi SP terubahsuai LNR-EB menunjukan perubahan sifat mekanik yang ketara. Nilai maksimum tegasan dan kekuatan impak adalah masing masing 6.7 MPa dan 13.2 kJ/cm2 pada dedahan 20 kGy dos EB, manakala modulus regangan adalah 79 MPa pada dos 30 kGy. Ini menunjukkan terdapat peningkatan interaksi berkesan antara-muka SP dan TPNR bagi SP terwat LNR pada dos 20-30kGy EB. Peningkatan dos EB pada SP tersalut LNR menyebabkan degradasi salutan NR dan meningkatakan interaksi antara zarah SP. Pengaglomerasian zarah SP akan berlaku dan menyebabkan serakan zarah dalam komposit menjadi tidak homogen.
Komposit 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.
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.
Kaedah pemarkahan dan penggredan sering dibincangkan dalam aspek penilaian pelajar. Kertas kerja ini bertujuan untuk membincangkan kaedah pemarkahan dan penggredan menggunakan persentil taburan markah. Kaedah pemarkahan dengan menggunakan min dan songsangan varians markah bagi setiap soalan dalam suatu peperiksaan sebagai pemberat kepada soalan berkenaan dibincangkan. Dalam membincangkan penggredan menggunakan persentil taburan markah, persentil boleh ditentukan dengan menganggar taburan bagi markah peperiksaan. Penganggaran dan penentuan persentil bagi dua taburan iaitu taburan normal dan taburan gamma digunakan. Perbandingan dilakukan terhadap keputusan bagi beberapa senario yang diperoleh. Keputusan menunjukkan bahawa kaedah pemarkahan berpemberat yang menggunakan pemberat yang berasaskan kepada tahap kesukaran soalan boleh digunakan untuk mernghasilkan peringkat gred yang lebih jelas dalam kalangan pelajar.
Rattans are one of the most unique and economically important plants for most tropical countries. There is however, a lack of interest in the specific study of the rattan spines. In this paper, we tested a new hypothesis concerning the functional role of rattan spines. We proposed that rattan spines also serve as a visual deterrent against herbivores or seed predators. In our proposed method we used an Imaging software, ImageJ, to measure the spine area of four species of rattan (Calamus insignis, Myrialepis schortechinii, Plectocomiopsis geminiflorus and Calamus caesius) from two different orientations (root to shoot and vice versa). Our results showed that rattan spines were very heterogeneous and highly variable between different species. One common trait that the rattan spines share is that spine area measurements of shoot to root (ShR) are larger than root to shoot (RH) orientation. We propose that the downwards spine angle might be specifically designed to discourage climbing leaf and seed predators.
This preliminary study aimed to isolate and identify microbes that inhabit the coelomic fluid of two local species of sea cucumbers collected from Malaysian waters - a ‘gamat’ species i.e. Stichopus chloronotus Brandt, 1835 and the most abundant ‘timun laut’ species in Malaysia i.e. Holothuria (Mertensiothuria) leucospilota (Brandt 1835). Phylogenetic analyses of partial 16S rRNA mtDNA gene sequences suggested the presence of at least eight microbial genera i.e. five bacterial genera - Bacillus, Exiguobacterium, Pseudomonas, Stenotrophomonas and Vibrio - isolated from the coelomic fluid of H. leucospilota and three genera of gram-positive bacteria from the Micrococcaceae family - Kytococcus, Micrococcus and either Kocuria or Rothia - isolated from the coelomic fluid of S. chloronotus. We speculate that less diverse microbial population in S. chloronotus as compared to H. leucospilota could be due to a number of environmental factors e.g. penetration of light surrounding the habitats of both species, the feeding behaviour of H. leucospilota and the higher level of antimicrobial properties of coelomic fluid in S. chloronotus. In terms of antimicrobial-resistance capability test, an isolate from genus Pseudomonas that is suspected to be P. alcaligenes exhibited high resistance towards streptomycin. Another isolate from genus Stenotrophomonas that was suspected to be S. maltophilia showed moderate resistance towards streptomycin and lower resistance towards kanamycin. Both isolates were from the coelomic fluid of H. leucospilota. Tetracycline inhibited the growth of all bacterial isolates tested. Further studies with more specimens of S. choronotus and H. leucospilota from broader geographical locations and the use of complete mtDNA genes along with morphological approaches for species identification may facilitate to provide better insights into the microbial population in the coelomic fluid of both local sea cucumber species.
Analysis of relationship between sea surface temperature (SST) and Chlorophyll-a (chl-a) improves our understanding on the variability and productivity of the marine environment, which is important for exploring fishery resources. Monthly level 3 and daily level 1 images of Moderate Resolution Imaging Spectroradiometer Satellite (MODIS) derived SST and chl-a from July 2002 to June 2011 around the archipelagic waters of Spermonde Indonesia were used to investigate the relationship between SST and chl-a and to forecast the potential fishing ground of Rastrelliger kanagurta. The results indicated that there was positive correlation between SST and chl-a (R=0.3, p<0.05). Positive correlation was also found between SST and chl-a with the catch of R. kanagurta (R=0.7, p<0.05). The potential fishing grounds of R. kanagurta were found located along the coast (at accuracy of 76.9%). This study indicated that, with the integration of remote sensing technology, statistical modeling and geographic information systems (GIS) technique were able to determine the relationship between SST and chl-a and also able to forecast aggregation of R. kanagurta. This may contribute in decision making and reducing search hunting time and cost in fishing activities.
One of the concerns of the air pollution studies is to compute the concentrations of one or more pollutants’ species in space and time in relation to the independent variables, for instance emissions into the atmosphere, meteorological factors and parameters. One of the most significant statistical disciplines developed for the applied sciences and many other disciplines for the last few decades is the extreme value theory (EVT). This study assesses the use of extreme value distributions of the two-parameter Gumbel, two and three-parameter Weibull, Generalized Extreme Value (GEV) and two and three-parameter Generalized Pareto Distribution (GPD) on the maximum concentration of daily PM10 data recorded in the year 2010 - 2012 in Pasir Gudang, Johor; Bukit Rambai, Melaka; and Nilai, Negeri Sembilan. Parameters for all distributions are estimated using the Method of Moments (MOM) and Maximum Likelihood Estimator (MLE). Six performance indicators namely; the accuracy measures which include predictive accuracy (PA), coefficient of determination (R2), Index of Agreement (IA) and error measures that consist of Root Mean Square Error (RMSE), Mean Absolute Error (MAE) and Normalized Absolute Error (NAE) are used to find the goodness-of-fit of the distribution. The best distribution is selected based on the highest accuracy measures and the smallest error measures. The results showed that the GEV is the best fit for daily maximum concentration for PM10 for all monitoring stations. The analysis also demonstrates that the estimated numbers of days in which the concentration of PM10 exceeded the Malaysian Ambient Air Quality Guidelines (MAAQG) of 150 mg/m3 are between ½ and 1½ days.
Minyak pati Goniothalamus ridleyi daripada sampel segar dan kering bahagian kulit batang, kayu, buah, akar dan
daun telah diekstrak menggunakan hidro penyulingan. Minyak pati tersebut telah dianalisis menggunakan kromatografi
gas (KG) kapilari dan kromatografi gas-spektrometer jisim (KG-SJ). Komposisi sebatian kimia dalam minyak pati telah
dikenal pasti secara perbandingan data spektrum jisim sampel dengan spektrum jisim yang ada dalam rujukan Wiley,
perbandingan pengiraan indeks penahanan dengan nilai kepustakaan dan ko-kromatografi bagi sesetengah sebatian
dengan sebatian autentik pada turus kapilari DB-5. Sebanyak 50 sebatian telah dikenal pasti dan mewakili 89.5% minyak
pati kulit batang segar G. ridleyi. Minyak pati daripada kulit batang segar kaya dengan sebatian linalool (15.2%) dan
sitronellal (10.9%). Sejumlah 47 sebatian telah dikenal pasti dan mewakili 90.1% jumlah minyak pati kayu segar yang
menunjukkan kehadiran sebatian utama β-eudesmol (27.1%) dan γ-eudesmol (20.8%). Sementara itu, minyak pati
daripada bahagian buah menunjukkan kehadiran 49 sebatian serta mewakili 89.8% jumlah minyak pati. Sebatian utama
dalam minyak pati buah adalah β-kubebena (20.7%) dan elemol (20.2%). Sebatian utama dalam sampel segar adalah
sama dengan sebatian utama dalam sampel kering, kecuali bahagian sampel kering didapati kaya dengan sebatiansebatian
seperti β-karyofilena, limonena, β-selinena, viridifloral, α-kopaena dan cyperena.
A study was conducted to determine the effects of a plant growth regulator (paclobutrazol, PBZ) and commercial
fertilizer (Krista-K Plus) as a source of potassium nitrate (KNO3
) on the growth of Xanthostemon chrysantus. It was
also attempted to investigate the anatomical changes in the leaf and stem after the treatment. Nine treatments, i.e.
control (no PBZ and Krista-K Plus application), 0 PBZ gL-1 + 100 g Krista-K Plus, 0 PBZ gL-1 + 200 g Krista-K Plus,
0.125 PBZ gL-1 + 0 g Krista-K Plus, 0.125 PBZ gL-1 + 100 g Krista-K Plus, 0.125 PBZ gL-1 + 200 g Krista-K Plus, 0.25
PBZ gL-1 + 0 g Krista-K Plus, 0.25 PBZ gL-1 + 100 g Krista-K Plus and 0.25 PBZ gL-1 + 200 g Krista-K Plus, were
tested. PBZ was soil drenched at the commencement of the study while Krista-K Plus was applied at three-month
intervals. Plant growth performances such as tree height, diameter at breast height, canopy diameter and leaf area
were recorded monthly throughout the study period. Stem and leaf samples were collected before the application
of treatments and after six months of treatments for anatomical observation by using electron microscope. Plant
height, diameter at breast height, crown diameter and leaf area were significantly reduced with the application of
PBZ. Palisade parenchyma thickness was increased by 33.83% with 0.25 PBZ gL-1 + 200 g Krista-K Plus, while only
2.44% increment recorded in the control tree. Xylem thickness in the stem was reduced by 21.81% after treated with
the highest dosage of PBZ, while the control tree only had 1.78% increment. Spongy parenchyma thickness in the leaf
was unaffected. However, palisade parenchyma was found the thickest after combined treatment with 0.25 PBZ gL-1
+ 200 g Krista-K Plus. Micrograph images of the cross-section of leaf lamina and stem showed that the cells were
tightly arranged in response to the application of PBZ.
Phytochemical studies were conducted on the stem bark, stem, root and fruit of Goniothalamus ridleyi (Annonaceae)
collected at Post Brooke, Gua Musang, Kelantan, Malaysia. Extraction using organic solvent followed by extensive
purification using standard procedure afforded an epoxystyryllactone, 5-acetoxyisogoniothalamin oxide (1) from the
stem bark and fruit; a styryllactone, 5-acetoxygoniothalamin (2) and a styrylpyrone, dehydrogoniothalamin (3) from
the stem and root; a styryllactone, 5-hydroxygoniothalamin (4) from the root and styrylpyrone as well as goniothalamin
(5) from the fruit. These compounds were characterized using spectroscopic techniques.
Introductions: Recurrent oral ulcers primarily effect mucosal surfaces and are among the most common chronic inflammatory diseases. Numerous studies to find the aetiopathogenesis have been conducted however the cause still remains unclear. Saliva is of utmostimportance for oral health maintenance. In current study, saliva was used as a diagnostic tool for comparison of salivary flow rate and pH in patients suffering from recurrent oral ulcers and control group. Materials and Methods: Saliva samples taken from 20 recurrent aphthous ulcer patients and 20 control (healthy) patients using a convient sampling method. Drooling method was used to collect unstimulated whole saliva sample. Pre-weighted specimen bottles were used and then weighed after sample collection on a graduated scale where as chair-side pH meter was used to determine the salivary pH. Independent t-test and Pearson’s correlation were performed. A p-value of less than 0.05 was considered statistically significance. Results: Positive correlation was found between the flow rate and pH in recurrent oral ulcer patients. Patients with recurrent oral ulcers had higher flow rate and pH compared to the control group. These effects were exaggerated in female patients with ulcers. Conclusions: Disturbances in salivary flow rate and pH were not significantly associated with recurrent oral ulcers.
The biosynthesis of nanoparticles has been proposed as a cost-effective and environmental friendly alternative to chemical and physical methods. The present study was aimed to characterise Catharanthus roseus (C. roseus)-silver nanoparticles (AgNPs) using a standardised C. roseus aqueous extract. Methods: The standardisation was performed by using Liquid Chromatography/Time-of-Flight ion trap Mass Spectrometry. An optimised C. roseus-AgNPs have been previously synthesised. Further characterisation of C. roseus-AgNPs was evaluated by zeta potential analysis and fourier transform infrared spectroscopy (FTIR). Results: The chromatography analysis has revealed presence of thirteen possible indole alkaloids in C. roseus extract which were lochrovicine, lochnerine, vinleurosine, vindolinine, tabersonine, catharanthine, serpentine, catharosine, vincristine, catharine, ajmalicine, vinleurosine, and vindolicine. Zeta potential analysis exhibited the value at -16.6 mV. FTIR spectrum of C. roseus aqueous extract showed the absorption band at 3210.83 cm-1 (C-H stretch), 2934.11 (C-H bond), 1578.15 (N=O stretch), 1388.76 and 1314.89 (N=O bend), 1119.29 (C-O bond) and 729.94 (C-Cl bond). In comparison, FTIR spectrum of C. roseus-AgNP s showed the absorption band at 2925.01 and 2924.97 (C-H bond), 1622.93 (C-C=C symmetric stretch), 1383.19 and 1384.13 (N-O bend), 1037.92/1038.76/1238.3/1117.2 (C-O bond), 3169.4 (O-H bond), 774.59 and 691.53 (C-Cl bond). Conclusion: The present findings have shown that the C. roseus aqueous extract contains alkaloids that may responsible as reducing and stabilising agents in the synthesis of AgNPs.
The changes on the vegetables oil trading environment might change the foundation of palm oil pricing and induce a structural change to the price model. Failing to take it account the structural change in a data series might lead to misspecification of the actual model. This study, however, showed that structural change was not present in the monthly, January 1983 to July 1995, palm oil price, but it was present on the unconditional variance. The underlying model of this series was ARIMA (3, 1, 0) with ARCH (1). The critical change of the unconditional variance took place in April 1989.
Perubahan dalam suasana perdagangan minyak sayuran boleh mengubah asas harga minyak kelapa sawit. Seterusnya ia merangsang perubahan dalam struktur model harga minyak tersebut. Kegagalan untuk mengambil kira perubahan struktur dalam siri data menjadikan model itu tidak menepati spesifikasi daripada model sebenar. Kajian ini mendapati bahawa perubahan struktur tidak berlaku bagi data harga minyak sawit dari Januari 1983 hingga Julai 1995. Tetapi perubahan berlaku pada varians tidak bersyaratnya. Model asas bagi siri ini adalah ARIMA (3,1,0) dengan ARCH(1). Didapati juga bahawa perubahan yang kritikal bagi varians tidak bersyarat berlaku pada bulan April 1989.