Browse publications by year: 2004

  1. Noriszura Hj. Ismail, Khairul Anuar Mohd Ali, Chiew A
    This research aims to fit discrete distributions on insurance claim count data. The fitting includes both single and finite mixture distributions. The data used is claim count data for life insurance products produced by one of the insurance companies in Malaysia. The claims were paid from January 2000 until December 2000, involving a period of 12 months. The method of moments and maximum likelihood procedure are used to estimate the parameters of both single and finite mixture distributions. The Pearson chi­square test, likelihood ratio test, and Bayesian Schwartz criteria are used to test the models. The results showed that finite mixture distribution is superior to single distribution. Furthermore, the results also showed that two-Poisson finite mixture distribution is the best model for the data.
    Kajian ini bertujuan untuk menyuai taburan diskrit terhadap data bilangan tuntutan insurans. Penyuaian yang dilakukan melibatkan taburan tunggal dan campuran terhingga. Data yang diguna merupakan data bilangan tuntutan bagi produk insurans hayat yang dikeluarkan oleh salah sebuah syarikat insurans yang terdapat di Malaysia. Data ini bertempoh 12 bulan, bermula daripada Januari 2000 sehingga Disember 2000. Kaedah momen dan kebolehjadian maksimum diguna untuk menganggar parameter bagi kedua-dua taburan tunggal dan campuran terhingga. Kebagusan suaian model diuji dengan ujian khi-kuasa dua Pearson, ujian nisbah kebolehjadian dan kriteria Bayesian-Schwartz. Hasil kajian menunjukkan bahawa model campuran terhingga memberikan penyuaian yang lebih baik berbanding dengan model tunggal. Selain itu, hasil kajian juga menunjukkan bahawa taburan campuran terhingga dua-Poisson adalah model yang terbaik bagi data.
  2. Naomie Salim, Holliday J, Willett P
    This paper describes experiments to study on how well the whole range of topological indices-based non-binary similarity values represents the physicochemical similarities between compounds. Measured log P values have been compared with the log P values predicted from compounds at different range of similarities calculated based on various topological indices of the compounds. Analysis shows that the non-binary Cosine, Simpson and Pearson coefficients might give misleading results when certain compounds are compared. Similarity values involving 1% most similar compounds based on the non-binary Tanimoto or Euclidean coefficients has been found to be able to represent physicochemical similarities between the molecules compared. Therefore, for searches requiring around 1% most similar compounds, rational selection methods based on the non-binary Tanimoto or Euclidean coefficients are likely to produce better results than random selection. Similarity values involving 5% most dissimilar compounds based on the non-binary Tanimoto coefficients has also been found to be able to represent physicochemical dissimilarities between the molecules compared. Therefore, for diverse selection requiring less than 5% most dissimilar compounds, rational selection methods based on the non-binary Tanimoto coefficient is likely to produce better results than random selection. However, in both focused and diverse selection using the coefficients mentioned, as more and more compounds are selected, the selection becomes more and more like random selection in terms of physicochemical properties similarity and dissimilarity.
    Kertas kerja ini membincangkan mengenai kajian untuk melihat sejauh mana nilai keserupaan bukan binari yang dihasilkan melalui perbandingan indeks topologi sebatian mampu mewakili perbezaan atau keserupaan ciri fizikal dan kimia sebatian yang dibandingkan. Di dalam kajian ini, nilai log P yang diperolehi daripada ujikaji makmal telah dibandingkan dengan nilai log P jangkaan yang diambil daripada purata log P sebatian yang mempunyai pelbagai julat nilai keserupaan tertinggi berdasarkan perbandingan indeks tolopologi kesemua sebatian di dalam pangkalan data dengan sebatian berkenaan. Analisa menunjukkan yang pengiraan keserupaan bukan binari menggunakan angkali Cosine, Simpson dan Pearson boleh memberikan nilai keserupaan yang mengelirukan apabila sesetengah jenis sebatian dibandingkan. Nilai keserupaan yang melibatkan 1% sebatian paling serupa berdasarkan angkali Tanimoto atau Euclidean didapati mampu menggambarkan keserupaan ciri fizikal dan kimia sebatian yang dibandingkan. Justeru, carian atau pemilihan berfokus bagi mendapatkan 1% sebatian paling serupa dengan sesuatu sebatian menggunakan angkali Tanimoto dan Euclidean ke atas perwakilan bukan binari sebatian dijangka berkecenderungan memberikan hasil yang lebih memuaskan berbanding dengan pemilihan rambang. Nilai keserupaan yang melibatkan 5% sebatian paling berbeza berdasarkan angkali Tanimoto juga didapati mampu menggambarkan perbezaan ciri fizikal dan kimia molekul yang dibandingkan. Ini menunjukkan yang pemilihan rasional berdasarkan angkali Tanimoto bagi memilih subset yang terdiri daripada 5% molekul paling rencam dari sebuah pangkalan data molekul yang mempunyai perwakilan bukan binari berkecenderungan untuk memberikan hasil yang lebih baik daripadapemilihan secara rambang. Walau bagaimanapun. di dalam kedua-dua pemilihan berfokus atau rencam menggunakan angkali yang dinyatakan, semakin banyak sebatian yang dipilih, hasil yang didapati semakin menyerupai pemilihan secara rawak dari segi keserupaan atau kerencaman ciri fizikal dan kimia.
    MeSH terms: Animals; Ataxia Telangiectasia; Color; Pallor; Gastropoda
  3. Kamaruzzaman Yunus, Ong MC, Kung YSW
    Bottom sediment samples from 19 stations of Terengganu River estuary were analyzed for the concentration of Co, Cu, Zn and Pb. The average concentration of Co, Cu, Zn and Pb were 7.01 ± 1.26 µg/g dry weight, 36.7 ± 25.9 µg/g dry weight, 83.3 ± 52.4 µg/g dry weight dan 122.5 ± 25. 7 µg/g dry weight, respectively. Generally, the concentration of Co, Cu, Zn and Pb at present are not widespread enough as to have much influence on pollution of that area. The concentration of these metals increased with the decrease of mean size, suggesting their association with the fine fraction of the sediment.
    Sampel sedimen dasar yang diperolehi daripada 19 stesen penyampelan di muara Sungai Terengganu telah dianalis is untuk mendapatkan taburan kepekatan Co, Cu, Zn dan Pb. Purata kepekatan bagi Co, Cu, Zn dan Pb adalah masing-masing 7.01 ± 1.26 µg/g berat kering, 36.7 ± 25.9 µg/g berat kering, 83.3 ± 52.4 µglg berat kering dan 122.5 ± 25.7 µg/g berat kering. Secara kesimpulannya, tahap pencemaran Co, Cu, Zn dan Pb adalah masih terkawal dan tidak menunjukkan tahap pencemaran logam berat yang serius. Kepekatan Logam didapati meningkat dengan pengurangan niLai min saiz partikel dan ini mengesyorkan hubungan logam yang baik terhadap sedimen yang lebih halus.
  4. Phuah CS, Che Abd Rahim Mohamed, Zaharuddin Ahmad
    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.
    MeSH terms: Background Radiation; Gamma Rays; Germanium; Scintillation Counting; Spectrometry, Gamma; Water
  5. Shaharudin Abdul Razak
    A study of the major Arthropoda taxa of invertebrates recolonizing Saraca roots occurring on various substrates and under various water velocities was carried out in the upper reaches of the Gombak River. The sites for the recolonization experiments were selected in the fast and slow flowing sections of rocks and boulders, sand and gravel and mud and silt biotopes. The Hydropsychidae and the Nemouridae were the pioneer recolonizers of Saraea roots in the fast flowing sections of the stream whereas the Ptilodactylidae and the Caenidae were the pioneer recolonizers in the slow flowing sections of the stream.
    Suatu kajian telah dijalankan bagi menentukan takson utama invertebrata Arthropoda yang mengkoloni semula akar Saraca yang didapati pada pelbagai substrat dan pada kelajuan air yang berbeza di bahagian hulu Sungai Gombak. Tapak-tapak untuk ujikaji pengkolonian-semula telah dipilih pada bahagian laju dan perlahan biotop batuan besar dan sederhana, pasir dan batuan kecil, dan lumpur dan kelodak. Hydropsychidae dan Nemouridae adalah pengkoloni perintis pada akar Saraca di bahagian aliran laju sungai sementara Ptilodactylidae dan Caeflidae adalah pengkoloni perintis di bahagian aliran perlahan sungai itu.
    MeSH terms: Animals; Arthropods; Invertebrates; Silicon Dioxide; Water; Plant Roots; Rivers; Ephemeroptera
  6. Sahibin Abd. Rahim, Mohamad Md. Tan, Ramlan Omar, Zulfahmi Abdul Rahman, Tukimat Lihan, Lim S
    Eleven marine sediment samples from Sg. Tengi Estuary, Tanjung Karang were analysed for their major elements in the oxides form (SiO2, Al2O3, Fe2O3, Na2O3, MgO, CaO, K2O, TiO2, P2O5 and MnO) and trace elements (Ba, Co, Cr, Cu, Ni, Pb, Rb, Sr, V, Zn, and Zr) contents. The muddy marine sediment was collected at the left and right side of the river mouth as far as one kilometre away and about 25-30 meters from the edge of existing growth. Some of the mud sample appears to have cockleshell flakes in them. The mean of major elemental content (oxides form) in the sediment in decreasing order were dominated by SiO2 (56.3%), followed by Al2O3, (15.5%), Fe2O3 (4.1%), Na2O (2.7%), CaO (2.6%), MgO (2.3%), K2O (1.8%), TiO2 (0.5%), P2O5 (0.14%) and MnO (0.06%). Volatile substances represented by loss on ignition (LOI) (13.9%) occupied substantial amounts of the sediment volume. The most abundant trace elements displayed as mean was Zr (222 mgkg-1), followed by Ba (200 mgkg-1), Sr (172 mgkg-1), Rb (131 mgkg-1), Zn (103 mgkg-1), V (l02mgkg-1), Cr (84 mgkg-1), Pb (40 mgkg-1), Ni (34 mgkg-1), Cu (31 mgkg-1) and Co (22 mgkg-1). Correlation analysis showed that Cr, Pb and Zn were positively related to the Fe203 and Al2O3 content whereas increase in pH immobilised Cr and Zn in the sediment. The mean of Cr (84 mgkg-1) and Zn (103 mgkg-1) content in sediment were higher than the lower limit of their respective threshold concentration.
    Sebanyak 11 sampel sedimen marin daripada muara Sg. Tengi, Tanjung Karang telah dianalisis untuk menentukan kandungan unsur major dalam bentuk oksida (SiO2, Al2O3 Fe2O3, Na2O3, MgO, CaO, K2O, TiO2, P2O5 and MnO) dan unsur surih (Ba, Co, Cr, Cu, Ni, Pb, Rb, Sr, V, Zn, and Zr). Sedimen marin berlumpur dikutip daripada bahagian kiri dan kanan muara sungai dalam jarak sejauh kira-kira 1 km dan 25-30 meter ke arah laut daripada kawasan pertumbuhan yang sedia ada. Sebahagian daripada sampel lumpur tersebut mempunyai kandungan serpihan kulit kerang. Purata kandungan unsur major di dalam sedimen mengikut urutan menurun adalah didominasi oleh SiO2 (56.27%) diikuti oleh Al2O3 (15.5%), Fe2O3 (4.1 %), Na2O (2.7%), CaO. (2.6%), MgO (2.3%), K2O (1.8%), TiO2 (0.5%), P2O5 (0.14%)dan MnO. (0.06%). Sebatian mudah meruap diwakili oleh kehilangan menerusi pembakaran (LOI) (13.9%) mengisi isipadu yang agak besar di dalam komposisi sedimen. Purata kandungan unsur surih yang terbanyak ditunjukkan. oleh Zr (222 mgkg-1), diikuti oleh Ba (200 mgkg-1), Sr (172 mgkg­-1), Rb (131 mgkg-1), Zn (103 mgkg-1), V (l02 mgkg-1), Cr (84 mgkg-1), Pb (40 mgkg-1), Ni (34 mgkg-1), Cu (31 mgkg-1) dan Co (22 mgkg-1). Analisis korelasi menunjukkan Cr, Pb dan Zn mempunyai hubungan positij yang signijikan dengan Fe2O3 dan Al2O3, manakala peningkatan pH memegunkan Cr dan Zn dalam sedimen. Purata kandungan Cr (84 mgkg-1) dan Zn (103 mgkg-1) di dalam sedimen lebih tinggi daripada paras yang dikira berpotensi toksik di dalam sedimen.
  7. Mahanem Mat Noor, Norazalia Mohd Ali
    Effect of Centella asiatica aqueous leaf extract was assessed on spermatogenesis and sperm quality in mice. The experiment was conducted by giving three different doses of C. asiatica extract orally; 25mg/kg, 50mg/ kg and 100mg/kg body weight daily for four weeks respectively. Control group was treated with normal saline (0.9% NaCl). Marked decreases in sperm count and motility were found in sperm collected from the cauda epididymis of treated mice. The treatment, however did not affect sperm mortality and morphology. Histologically, signs of inhibition of testicular cells appeared clearly at dose 100mg/kg, when the lumen of seminiferous tubules were only full with spermatocytes and spermatids. The present results show that the plant has antispermatogenic effect in mice. It is therefore, suggested that leaf extracts of C. asiatica possess antifertility activity in male mice.
    Kesan ekstrak berakua daun Centella asiatica telah dikaji ke atas proses spermatogenesis dan kualiti sperma mencit. Kajian dijalankan dengan memberikan tiga dos C. asiatica secara oral masing-masing; 25mg/kg, 50mg/ kg and 100mg/kg berat tubuh mencit setiap hari selama empat minggu. Kumpulan kawalan diberikan larutan salin normal (0.9% NaCl). Pengurangan dalam bilangan dan motiliti sperma yang ketara telah diperhatikan pada semua kumpulan mencit yang diberikan ekstrak C. asiatica. Walau bagaimanapun pemberian ekstrak C. asiatica tidak mendatangkan kesan terhadap mortaliti dan morfologi sperma. Kajian histologi pula menunjukkan terdapat kesan perencatan sel-sel spermatogenik testis pada dos C. asiatica 100mg/kg di mana lumen pada tubul seminiferus hanya dipenuhi dengan sel-sel spermatosit dan spermatid. Hasil kajian menunjukkan tumbuhan ini mempunyai kesan antispermatogenik pada mencit. Oleh itu dicadangkan bahawa ekstrak daun C. asiatica mempunyai aktiviti antikesuburan pada mencit jantan.
    MeSH terms: Animals; Antispermatogenic Agents; Body Weight; Epididymis; Humans; Male; Seminiferous Tubules; Sperm Count; Spermatids; Spermatocytes; Spermatogenesis; Spermatozoa; Testis; Triterpenes; Centella; Control Groups; Mice
  8. Mahanem Mat Noor, Chuay SH
    The mengkudu (Morinda citrifolia Linn.) plant is a well known medicinal plant. The fruits, leaves and roots of this plant have been widely used in traditional medicine. The purpose of this study was to evaluate the effects of an aqueous extract of the M. citrifolia fruits (25 mg/kg, 50 mg/kg and 100 mg/kg body weight given for a period of 30 days) on sperm quality and histology of testis in mice. Data from this study show that the epididymal sperm count, mortality, motility and sperm morphology in mice given the M. citrifolia fruit extract did not differ from that of the control group. Spermatogenesis was not affected by the treatment. The results obtained here suggest that the aqueous extract of the M. citrifolia fruit (up to 100 mg/kg) did not affect sperm quality and spermatogenesis in mice.
    Mengkudu (Morinda citrifolia Linn.) adalah tumbuhan ubatan yang terkenal. Bahagian buah, daun dan akarnya digunakan secara meluas dalam perubatan tradisional. Kajian ini dijalankan untuk menentukan kesan pemberian ekstrak berakua buah M. citrifolia (dos 25mg/kg, 50 mg/kg dan 100 mg/kg berat tubuh mencit selama 30 hari) ke atas kuantiti sperma dan histologi testis mencit. Data daripada kajian ini menunjukkan bilangan sperma epididimis, mortaliti, motiliti dan morfologi sperma mencit kajian tidak berbeza berbanding kumpulan kawalan. Proses spermatogenesis juga tidak terjejas dengan pemberian M. citrifolia. Keputusan kajian ini mencadangkan ekstrak berakua M .citrifolia (sehingga 100 mg/kg) tidak mendatangkan kesan terhadap kualiti sperma dan spermatogenesis mencit.
    MeSH terms: Animals; Body Weight; Epididymis; Fruit; Humans; Male; Medicine, Traditional; Plants, Medicinal; Sperm Count; Spermatogenesis; Spermatozoa; Testis; Plant Leaves; Morinda; Control Groups; Mice
  9. Wan Zuraida Wan Mohd Zain, Nik Loris Yusoff, Jalifah Latip, Bohari M. Yamin
    Andrographolide was separated from Andrographis paniculata Nees by using column chromatography and recrystallized from methanol. 1H and 13C NMR, IR, UV spectroscopic and GCMS data were in agreement with the previous report. The crystallined product has a monoclinic system with space group P21, a=6.541(1), b=8.003(1), c=17.962(2) Å and β=97.39(1)19o. The bicyclohexane fragments have a chair conformation with the methyl and the methylene hydroxyl groups occupying the axial position, while the OH and the C2-lactone are in the equatorial positions. The bond lengths and the angles are in the normal ranges. There are two intramolecular interactions of the type O-H … O and C-H …. O in the molecule. The molecule is stabilized by two interhydrogen bonds O-H … O and C-H … O to form polymeric chains parallel to b-axis.
    Andrografolid telah dipisahkan daripada herba Andrographis paniculata Nees dengan kaedah kromatografi turus dan dihablur semula daripada metanol. Analisis spektroskopi RMN 1H dan 13C, 1M, UL, KGSJ bersetuju dengan laporan terdahulu. Hablur produk mempunyai sistem monoklinik dengan kumpulan ruang P21, a=6.541(1), b=8.003(1), c=I7.962(2)Å dan β =97.39(1)°. Fragmen bisikloheksana berkonformasi kerusi dengan kumpulan metil dan CH2OH mengisi kedudukan paksi. Kumpulan OH serta C2-lakton berada di kedudukan khatulistiwa. Panjang dan sudut ikatan adalah normal. Terdapat dua ikatan intrahidrogen O-H .... O dan satu C-H .. O. Molekul distabilkan oleh dua ikatan interhidrogen O-H ……O dan C-H .… O membentuk rangkaian polimer tak terhingga selari dengan paksi- b.
  10. Nur Azlinawati Md. Khlid, Musa Ahmad
    Optical sensing material for detection of pH has been prepared by immobilising phenol red in nafion membrane. Glass slides with dimension 3 in × 1 in were used as a support. The nafion membrane doped with phenol red was characterized by using uv-Visible Spectrophotometer to study the responses at different pH, repeatability and photo stability. The sensing materials were able to be used for the development of an optical pH sensor since the reagent could be successfully immobilised and produced good responses at different pH.
    Bahan sensor untuk pengesanan pH telah disediakan dengan memegunkan reagen fenol merah dalam membran nafion. Slaid kaca yang berukuran 3 in × 1 in telah digunakan sebagai penyokong. Setelah dipegunkan. membran terdop dengan reagen fenol merah dicirikan menggunakan Spektrofotometer uL-Nampak untuk mengkaji kebolehulangan. kestabilan foto dan kesan terhadap pH berbeza. Hasil kajian menunjukkan bahawa bahan ini boleh digunakan sebagai bahan sensor dalam pembinaan sensor optik pH kerana reagen berjaya dipegunkan dan memberikan rangsangan yang baik pada pH yang berbeza.
  11. Hasliza Yusof, Laily Din, Zuriati Zakaria, Kamarudin Mat Salleh
    A new species from the Goniothalamus genus, G. tomentosus, was investigated. Two alkaloids, aristololactam BII 1 and ouregidione 2 together with a stigmasterol isolated from the stem bark and roots were identified using spectroscopic techniques.
    Spesies baru daripada genus Gonitothalamus, G. tomemtosus telah dikaji. Dua sebatian alkaloid aristololaktam BII 1 dan ouregidion 2 serta stigmasterol yang dipencilkan daripada kulit batang dan akar telah ditentukan dengan menggunakan teknik spektroskopi.
    MeSH terms: Alkaloids; Aporphines; Spectrum Analysis; Stigmasterol; Aristolochic Acids; Goniothalamus
  12. Khor SM, Lee YH, Musa Ahmad
    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 ion­-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.
  13. Normah Awang, Ibrahim Baba, Yang Farina Abd. Aziz, Bohari M. Yamin
    Two adducts of bis(N-benzyl-N-isopropyldithiocarbamato) zinc(II) with 2,2'­-bipyridine and 1,10-phenanthroline have been successfully synthesized and characterized by elemental analysis and spectroscopic studies. The IR spec­tra of these adducts showed the thioureide band, v(C---- N) which occurred at 1440 and 1438 cm-1 respectively, lower than the parent compound at 1471 cm-1. The 13C NMR spectroscopic data for these compounds showed that the carbon signal from CS2 moiety shifted slightly downfield to 206.6 and 208.5 ppm compared to the parent compound at 205.1 ppm. The single crystal structure of bis (N-benzyl-N-isopropyldithiocarbamato )zinc(II)(bipy) has been determined. The structure of this compound showed monomeric nature with hexacoordination of the metal in a highly distorted octahedral geometry.
    Dua sebatian aduk zink(II) benzilisopropilditiokarbamat dengan ligan 2,2-bipiridil dan 1,10-fenantrolin telah berjaya disediakan dan dianalisis menggunakan analisis unsur dan kaedah spektroskopi. Spektrum IR untuk kedua-dua sebatian aduk ini telah menunjukkan kehadiran jalur tioureida, V(C----- N) pada 1440 dan 1438 cm-1 masing-masing yang mana jalur serapan ini didapati teranjak pada nilai yang lebih rendah berbanding sebatian asalnya iaitu pada 1471 cm-1. Data RMN 13C pula menunjukkan kehadiran signal karbon CS2 yang teranjak sedikit ke medan yang lebih rendah iaitu pada 206.6 dan 208.5 ppm masing-masing jika dibandingkan dengan sebatian asalnya pada 205.1 ppm. Struktur hablur tunggal bagi sebatian bis( N-benzil­-N-isopropilditiokarbamat)zink(11)(bipy) telah ditentukan. Struktur sebatian ini didapati bersifat monomerik dan berkoordinat enam dengan atom logam pusatnya mempunyai geometri oktahedron yang sangat terherot.
  14. Normah Awang, Ibrahim Baba, Yang Farina Abdul Aziz
    New organotin(IV) sec-butylpropyldithiocarbamate complexes have been suc­cessfully synthesized by the reaction between N-sec-butyl-N-propylamine, carbon disulfide and organotin(IV) chloride (dimethyltin(IV), dibutyltin(IV) and triphenyltin(lV) chloride) using in-situ method. All the complexes have been characterized using elemental analysis, gravimetric analysis, infrared and NMR (1H and I3C) spectroscopy. Elemental and gravimetric analyses showed that the complexes agree with the suggested formulae, R2Sn[S2CN( s­C4H9)(C3H7)]2 dan R‘3Sn[S2CN(s-C4H9)(C3H7)] (R = CH3 or R = C4H9; R' = C6H5 The presence of the v(C = N) and v(C = S) bands in the infrared spectra confirmed the presence of dithiocarbamate ligand in that complex. The 13C NMR spectra for all the complexes showed a resonance in the region 196.22 - 200.62 ppm, which is attributed to the carbon atom of NCS2 group. The dimethyltin(lV) sec-butylpropyldithiocarbamate, Me2Sn(SBPDtc)2 was recrystallized from CHCl3 and the structure had been determined using X-ray crystallography analysis. The structure of Me2Sn[s-C4H9)(C3H7)]2 is found to be in the monoclinic system with space group P21/n, a = 14.358(2), b = 10.6956(18), c = 17.323(3) Å; α = 90°, β = 99.765(4)°, γ = 90°. The complex is six-coordinated with the tin atom bonded by two dimethyl groups in cis positions and two chelating sec-butylpropyldithiocarbamates in bidentate mode.
    Kompleks baru organostanum(IV) sek-butilpropilditiokarbamat telah berjaya disediakan melalui tindak balas di antara N-sek-butil-N-propilamina, karbon disulfida dan sebatian dimetilstanum(lv), dibutilstanum(IV) dan trifenilstanum(IV) klorida menggunakan kaedah in-situ. Kesemua kompleks telah dicirikan menggunakan analisis unsur, analisis gravimetri, spektroskopi inframerah dan spektroskopi resonans magnet nukleus 1H dan 13C. Analisis unsur (CHNS) dan gravimetri menunjukkan sebatian yang disintesis bersetuju dengan formula yang dicadangkan, iaitu R2Sn[S2CN(s-C4H9)(C3H7)]2 dan R'3Sn[S2CN(s-C4H9)(C3H7] (R = CH3 atau C4H9; R' = C6H5). Kehadiran jalur serapan v(C ---- N) dan v(C ---- S) pada spektrum inframerah menunjukkan kehadiran ligan ditiokarbamat dalam sebatian yang disediakan. Spektrum RMN I3C bagi ketiga-tiga kompleks menunjukkan resonan N13CS2 terletak pada julat 196.22- 200.61 ppm. Kompleks dimetilstanum(1V) sek­bufilpropilditiokarbamat telah berjaya dihablurkan menggunakan pelarut kloroform. Kajian kristalograji sinar-X menunjukkan hablur Me2Sn[s-­C4H9)(C5H7)]2 bersistem monoklinik dengan kumpulan ruang P21/n, a = 14.358(2), b = 10.6956(18), c = 17.323(3) Å; α = 90°, β= 99.765(4)°, γ = 90°. Kompleks membentuk geometri enam koordinat dengan atom pusat stanum yang berikat dengan dua kumpulan metil pada kedudukan sis dan mengkelat secara bidentat dengan ligan sek-butil propilditiokarbamat.
  15. Jamaluddin Mohd Daud, Nor Azlina Zainal Abidin
    A faster method for sample preparation and qualitative analysis of phytohormones, i.e. abscisic acid (ABA), indole-3-acetic acid (IAA) and 1­-aminocyclopropane-l-carboxylic acid (ACC) is reported. Solid phase extrac­tion of Umbellifereae sp. plant extract was performed using C18 catridge ana the effluent collected was reacted to form the pentafluorobenzyl derivatives of ABA, IAA and ACC mixture. The derivatives mixture was separated and negative ion chemical ionization was carried out by using methane in a gas chromatograph-mass spectrometric instrument (GC-MS). Mass spectra of the three phytohormones are quite simple and therefore suitable for selective ion monitoring (S/M) at high sensitivity, together with their respective internal standards labeled with deuterium. However, only IAA can be determined quantitatively by GC-MS technique through the peak area ratio of SIM chromatograms for m/z 179 with m/z 174. This method allows the correction for the loss of IAA endogen during extraction when compared to the internal standard without the need for precise sampling, except during addition of the internal standard. The detection limit of IAA by this method is 5 femtomole/g wet weight of the plant.
    Satu kaedah penyediaan sampel dan analisis kualitatif yang pantas bagi fitohormon iaitu asid absisik (ABA), asid indol-3-asetik (IAA) dan asid 1­-aminosiklopropana-l-karboksilik (ACC) dilaporkan. Ekstrak daripada tumbuhan Umbellifereae sp. dilakukan pengekstrakan fasa pepejal dengan menggunakan katrij C18 dan efluen yang dipungut ditindakbalaskan bagi membentuk terbitan pentafluorobenzil bagi campuran ABA, IAA dan ACC. Campuran terbitan tersebut dipisahkan dan dilakukan pengionan kimia ion negatif dengan menggunakan metana di dalam instrumen kromatografi gas-spektrometri jisim (GC-MS). Spektrum jisim tiga hormon tersebut agak mudah dan oleh itu adalah sesuai bagi pemonitoran ion terpilih (S/M) pada kepekaan tinggi bersama dengan piawai dalaman masing-masing yang berlabel deuterium. Walau bagaimanapun, penentuan kuantitatif hanya dapat dilakukan untuk IAA menggunakan kaedah GC-MS melalui penisbahan luas puncak kromatogram S/M bagi m/z 179 dengan m/z 174. Ini membolehkan pembetulan kehilangan IAA endogen semasa pengekstrakan berbanding piawai dalaman tanpa perlu pensampelan yang teliti, kecuali semasa penambahan piawai dalaman. Had pengesanan bagi IAA melalui kaedah ini ialah 5 femtomol/g berat basah tumbuhan.
  16. Ishak Ahmad, Mohd Khairil Saat, Ibrahim Abdullah, Azizah Baharum
    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.
    MeSH terms: Bone Screws; Hardness; Microscopy, Electron, Scanning; Polymers; Rubber; Silicone Elastomers; Tensile Strength; Gentiana
  17. Rusli Daik, Quek MF
    Poly(4,4'-diphenylene diphenylvinylene) was synthesised from 4,4'­ dibenzoylbiphenyl with TiCl4 and zinc dust as the catalyst and reducing agent respectively in THF. 4,4' -Dibenzoylbiphenyl was prepared via Friedel-Crafts reaction with benzoylchloride and biphenyl as starting materials. The cata­lyst used was anhydrous AlCl3 Elemental analysis, GCMS chromatogram, FTIR spectrum and melting point measurement indicated that 4,4'­dibenzoylbiphenyl was obtained with 100% purity. The polymer was success­fully obtained with mass recovery of 72%. Glass transition, Tg and degrada­tion, temperature, Td found were 196°C and 465°C, respectively. Number average molecular weight and weight average molecular weight found were 7,400 g/mol and 15,500 g/mol as measured by using gel permeation chroma­tography. Conductivity of the pristine polymer was 8.3 x 10-11 Scm-I, whereas maximum conductivity found for LiCLO4 and iodine doped samples were 1.7 x 10-7 Scm-1 (2007 fold increase) and 5.5 x 10-9 Scm-1 (66 fold increase) with 18.75% and 37.50% of optimum doping contents respectively.
    Poli(4,4'-difenilena difenilvinilena) telah disintesis daripada 4,4'­-dibenzoilbifenil menggunakan TiCl4 dan serbuk zink masing-masing sebagai mangkin dan agen penurun di dalam THF. 4,4'-Dibenzoilbijenil telah disediakan melalui tindak balas Friedel-Crafts daripada benzoilklorida dan bijenil sebagai bahan mula dan AlCl3 kontang sebagai mangkin. Analisis unsur, kromatogram GCMS, spektrum FTIR dan penentuan takat lebur menunjukkan sebatian 4,4' -dibenzoilbifenil telah berjaya diperolehi dengan ketulenan 100%. Polimer telah berjaya disintesis dengan pengumpulan semula bahan sebanyak 72%. Suhu peralihan kaca, Tg dan suhu penguraian terma, Td bagi polimer masing-masing adalah 196°C dan 465°C. Kromatografi penelapan gel menunjukkan polimer yang dihasilkan mempunyai jisim molekul purata nombor dan jisim molekul purata berat masing-masing adalah 7,400 g/mol dan 15,500 g/mol. Kekonduksian polimer asal adalah 8.3 x 10-11 Scm-1, manakala kekonduksian maksimum polimer terdop LiClO4 dan iodin masing-masing adalah 1.7 x 10-7 Scm-I (peningkatan sebanyak 2007 kali ganda) dan 5.5 x 10-9 Scm-1 (peningkatan sebanyak 66 kali ganda) dengan kandungan agen pendop optimum sebanyak 18. 75% dan 37.50%.
  18. Lee YH, Zuriati Zakaria, Zanal Mohd Zain, Hazimin Harun, Farrah Anis Fazliatul Adnan, Suhaida Mohd Redzuan
    An investigation of the effect of discharge of domestic sewage to rivers at Kajang (Jeluh and Langat River) and coastal waters at Negeri Sembilan (Port Dickson and Blue Lagoon) was carried out. The parameters studied focused on the characteristics of sewage such as organic content (biochemi­cal oxygen demand, BOD and nutrients (dissolved phosphate, (PO4) and nitrate (NO)). The discharge of domestic sewage from oxidation ponds near Kajang has resulted in high levels of BOD and PO4 in river water, i.e. 1.9-5.1 and 0.15-2.03 mg/L respectively. The increase in BOD is correlated (r =0.77) with the decrease in the level of dissolved oxygen (DO) in the river water. In general. the effects of domestic sewage discharge on water quality is more obvious in the Jeluh and Langat rivers at Kajang when compared to the effect on marine water.
  19. Yip FW, Yang Farina, Ibrahim Baba, Abdul Hamid Othman
    Organostannum(IV) complexes derived from dicarboxylic acids have been successfully synthesised from triphenylstannum(IV) hydroxide (Ph3SnOH). The complexes were obtained by refluxing Ph3SnOH and the respective dicarboxylic acids (malonic, succinic, glutaric and adipic acids) using a Dean and Stark apparatus in the appropriate solvent. The free ligands and complexes were characterised by C, Hand Sn elemental analysis and spectroscopic methods such as infrared and nuclear magnetic resonance (1H, 13C NMR). Structure determination of triphenylstannum(IV) succinate, 2, showed that each dicarboxylate anion was bonded monodentatically to two triphenylstannum(IV) moieties. The geometry surrounding each stannum atom is close to a tetrahedron. Spectroscopic data obtained for all complexes were found to be similar and thus it may be concluded that all complexes have the same structure as 2.
    MeSH terms: Adipates; Dicarboxylic Acids; Hydroxides; Ligands; Solvents; Tin; Succinic Acid; Carbon-13 Magnetic Resonance Spectroscopy
  20. Ahmad Puaad Othman
    Computer simulations is now becoming a common feature in many under­graduate physics textbook together with online supplements to supposedly enhance learning and understanding. Many questions arise as to how these computer simulations and online supplements are developed and is it a worthy investment on the part of the physics educators. In this paper we look at the ways how "Physlets" (Physics Applets) are developed for the purpose of the undergraduate physics curriculum. JAVA is the fastest-growing pro­gramming language today. In scientific programming, the JAVA language meets the need for a simpler object-oriented language than C++ but is not yet popular, useful and widely used in very large scale or number crunching physics simulations. One of JAVA applets’s strength is that it is device independent. And for physics learning, simulation applets embedded in World Wide Web pages allow interactive learning and students-programmable demonstrations. We will examine a few physics simulations using JAVA applets that we have developed. We also discuss the various different aspects of using JAVA applets in developing physics simulation. And finally we will look into the reasons as to why it is still not ready for use in intensive physics simulation.
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