Spatial and temporal variations in silica concentration were determined at various rivers and tributaries in the Linggi River Basin, which has been highly polluted due to urban, industrial and agricultural wastes. The silica content measured as reactive silicate in the whole Linggi River Basin ranged from 1.4 to 26.3 mg/L. A clear seasonal variation in silica was noted especially in the major rivers with higher concentration during dry months and lower concentration during the wet months. The concentration was found to decrease as the water flooded downstream. The large drainage area with granite dominated lithology and high denudation especially in the upper catchment is attributed for high silica content in the water of Linggi River Basin.
Sebahagian hujan akan diperangkap oleh lapisan kanopi pokok dan permukaan lain sebagai pintasan, sebelum tersejat kembali ke atmosfera. Air hujan menuruni kanopi hutan melalui dua mekanisme; aliran batang dan jatuhan langsung. Aliran batang merujuk kepada jumlah air hujan yang sampai ke permukaan tanah dengan menuruni batang pokok dan dahan. Manakala jatuhan langsung pula merujuk kepada jatuhan terus air hujan yang menembusi lapisan kanopi hutan melalui ruang-ruang antara daun dan menitis dari daun, cabang dan dahan pokok. Kedua-dua komponen ini dinilai menggunakan plot pintasan bersaiz 100 ×100 m2 di hutan sekunder Tasik Chini. Tiga puluh batang pokok telah digunakan dan setiap pokok dikenal pasti berdasarkan spesies, famili, diameter aras dada (DBH) saiz kanopi dan ketumpatan kanopi. Dalam kajian ini, data pintasan telah dikumpulkan pada dua kali kejadian hujan yang berlaku dalam bulan November 2007 (44.51% dalam bentuk jatuhan langsung dan 55.49% dalam bentuk aliran batang) dan taburan hujan dalam bulan Disember 2007 (39.65% dalam bentuk jatuhan langsung dan 60.35% dalam bentuk aliran batang). Kajian pintasan ini menghasilkan maklumat penting bagi kitaran hidrologi yang berlaku dalam ekosistem hutan, juga keseimbangan air tanah bencah.
Surfactants in the atmosphere may act as cloud condensation nuclei, with a potentially negative impact on the global climate. Therefore, accurate determination of surfactants is crucial in order to investigate the possible effects of surfactants on the atmosphere. The aim of this study was to identify the optimum sampling method for measuring the maximum quantity of surfactants present in ambient air. Air samples were collected using a range of air sampling pumps that were made to vary in terms of flow rate, storage period, type of absorbing solution and the characteristics of the impinger tube. Samples obtained were analysed by colourimetry for anionic and cationic surfactants as methylene blue-active substances (MBAS) and disulphine blue-active substances (DBAS), respectively. Absorbance was measured at 650 nm for MBAS and 628 nm for DBAS using UV-visible spectrophotometer. We found that the optimum sampling method consisted of an absorbent solution (deionised water, buffer solution and methylene blue/disulphine blue solution) with the flow rate of 1.0 L/min. The concentration of surfactants in all sampling methods remained constant regardless of the storage period (1 day and 4 days), indicating that surfactants in the absorbing solution are quite stable. Covering the impinger tube was shown to influence the amount of both anionic and cationic surfactants detected.
Biomass burning is one of the main sources of air pollution in South East Asia, predominantly during the dry period between June and October each year. Sumatra and Kalimantan, Indonesia, have been identified as the regions connected to biomass burning due to their involvement in agricultural activities. In Sumatra, the Province of Riau has always been found to have had the highest number of hotspots during haze episodes. This study aims to determine the concentration of five major pollutants (PM10, SO2, NO2, CO and O3) in Riau, Indonesia, for 2006 and 2007. It will also correlate the level of air pollutants to the number of hotspots recorded, using the hotspot information system introduced by the Malaysian Centre for Remote Sensing (MACRES). Overall, the concentration of air pollutants recorded was found to increase with the number of hotspots. Nevertheless, only the concentration of PM10 during a haze episode is significantly different when compared to its concentration in non-haze conditions. In fact, in August 2006, when the highest number of hotspots was recorded the concentration of PM10 was found to increase by more than 20% from its normal concentration. The dispersion pattern, as simulated by the Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT), showed that the distribution of PM10 was greatly influenced by the wind direction. Furthermore, the particles had the capacity to reach the Peninsular Malaysia within 42 hours of emission from the point sources as a consequence of the South West monsoon.
MeSH terms: Agriculture; Air Pollutants; Air Pollution; Indonesia; Malaysia; Sulfur Dioxide; Wind; Biomass; Particulate Matter; Remote Sensing Technology
Four species of bacteria, Acinetobacter lwoffii, Aeromonas hydrophila, Pseudomonas aeruginosa and Pseudomonas putida, were isolated from soil contaminated with hydrocarbons and selected for the determination of growth requirements and the ability to degrade petroleum hydrocarbon. The bacteria were grown in mineral salt medium (MSM) supplemented with two types of crude oil, either Sumandak or South Angsi at 1% (v/v) concentration. The optimum pH for growth of A. hydrophila and P. aeruginosa was 6.5 when grown with Sumandak and South Angsi oil. For A. lwoffii and P. putida the optimum pH for growth with Sumandak and South Angsi oil was 6.5 or 7.0, respectively. The growth of P. aeruginosa was the highest in MSM when supplemented with 1% South Angsi oil and 0.5% tryptone at pH 6.5 while, in Sumandak oil the growth was the highest when yeast extract was added. Gas chromatography analysis showed that the South Angsi crude oil components of C12 to C25 were more extensively degraded by A. lwoffii after 24 h of incubation compared to the other bacteria over the same period.
On 3 January 2008, one specimen of Goonch Bagarius yarrelli (Sykes 1839) (Siluriformes: Sisoridae) was caught by a conventional beach seine in the lower part of the Ganges River, NW Bangladesh. The specimen constitutes a new record of maximum length and weight for the Ganges River and the South Asia.
MeSH terms: Animals; Asia; Bangladesh; Body Weight; Catfishes; Humans; Asian Continental Ancestry Group; Rivers
The development of alternative strategies for sustainable pests’ management in vegetable production (using insecticides of plant origin) is particularly important in a country like Nigeria where synthetic insecticides are not readily available and farmer s are poorly equipped to handle them. This research was conducted to unravel farmers’ perception of insect pest activities as a constraint to vegetable production and to ascertain the most important pests and indigenous methods of control (using plant extracts). Baseline surveys were conducted using well structured questionnaire on farmers’ plots in farming communities of Akure North and South Local Government Areas of Ondo State. Results from the study affirmed, that all the farmers had the problem of pests on their farms. They have ranked Podagrica sjostedti, P. uniforma, Sylepta derogata, Dsydercus superstitiosus, and Zonocerous variegata as the most important insect pests of the selected leaf vegetables: Amaranthus hybridus, Celosia argentea, and Corchorus olitorius. The results further indicated that 76% of the farmers were aware of the use of indigenous methods of control (using different plant extracts) for the control of pests. The study showed that there was no significant association between education and the use of plant extracts. However, age, sex, and farming experience influenced the use of the plant extracts for insect pest control on the respondents’ farm.
In this paper, the homotopy-perturbation method (HPM) is applied to obtain approximate analytical solutions for the Cauchy reaction-diffusion problems. HPM yields solutions in convergent series forms with easily computable terms. The HPM is tested for several examples. Comparisons of the results obtained by the HPM with that obtained by the Adomian decomposition method (ADM), homotopy analysis method (HAM) and the exact solutions show the efficiency of HPM.
This paper gives a comprehensive discussion on complex regression model by extending the idea of regression model to circular variables. Various aspect have been considered such as the biasness of parameters, error assumptions and model checking. The advantage of this approach is that it allows the use of usual technique available in ordinary linear regression for the regression of circular variables. The quality of the estimates and the feasibility of the approach were illustrated via simulation. The model was then applied to the wave direction data.
MeSH terms: Paper; Radiation; Models, Statistical; Linear Models; Electromagnetic Phenomena
Data envelopment analysis (DEA) is a mathematical programming for evaluating the relative efficiency of decision making units (DMUs). The first DEA model (CCR model) assumed for exact data, later some authors introduced the applications of DEA which the data was imprecise. In imprecise data envelopment analysis (IDEA) the data can be ordinal, interval and fuzzy. Data envelopment analysis also can be used for the future programming of organizations and the response of the different policies, which is related to the target setting and resource allocation. The existing target model that conveys performance based targets in line with the policy making scenarios was defined for exact data. In this paper we improved the model for imprecise data such as fuzzy, ordinal and interval data. To deal with imprecise data we first established an interval DEA model. We used one of the methods to convert fuzzy and ordinal data into the interval data. A numerical experiment is used to illustrate the application to our interval model.
Polycrystalline compounds of Ba(Ce1-xZrx)0.95Yb0.05O2.975 (0.20 ≤ x ≤ 0.40) were prepared by the conventional solid state reaction method. All the samples exhibited the orthorhombic structure of BaCeO3. The particle size and morphology of the powdered samples were found to change gradually with Zr content. The sample with x=0.40 showed more agglomerates of about 10.0 μm in size, and the particles constituting the agglomerates were smaller than 1.0 μm. For the polished and etched pelleted samples, only the x=0.20 sample showed clear grain shapes with sizes in the range of 1.0 to 3.0 μm. By increasing the Zr content to more than 20 mol%, the grain sizes became less pronounced and smaller. The deficiency of Ba that caused the formation of a Ce, Zr and Yb-rich sample was detected by energy dispersive X-ray measurement. Ba deficiency was attributed to the loss of BaO during the calcination and sintering processes.
This paper reports on the synthesis and characterization of CdTe-CdSe core-shell quantum dots (QDs) with luminescent from 650 to 720 nm. The QDs were synthesized using a wet-chemical process at a moderate temperature (300 °C) following two-steps process of core and shell synthesis. The photoluminescence characterization on the QDs showed that the QDs emitted light in the range of red regime with quantum yield as high as 37%. Owing to their unique photoluminescence characteristics (high quantum yield and narrow spectrum), the QDs may find a potential application in a variety of applications such as LED, solar cell and bio-labeling.
Halangan utama untuk mengkomersialkan mikro sel fuel metanol langsung (μSFML) sebagai sumber kuasa bagi peralatan mudah alih adalah prestasi sel fuel itu sendiri. Dalam kajian ini, didapati penghasilan keluaran kuasa yang tinggi oleh μSFML iaitu 14.10 mW pada 4 cm2 keluasan kawasan aktif dengan menggunakan muatan mangkin yang rendah, 0.5 mg cm-2 pada bahagian katod telah diperolehi. Penentuan parameter-parameter reka bentuk yang optimum juga telah dikenal pasti. Di samping itu, pengujian ke atas prestasi, jangka hayat dan voltan arus terbuka (OCV) turut dilakukan.
Kajian ini dijalankan untuk membangunkan pencerai optik 1×12 berasaskan gentian optik polimer (POF) diperbuat daripada polimetil metakrilat (PMAA) sebagai media penghantar isyarat optik berprestasi tinggi. Pada asasnya, peranti optik ini mempunyai 1 pangkalan POF masukan dan 12 pangkalan POF keluaran dalam bentuk gentian terberkas. Banyak sistem yang menggandingkan atau menceraikan isyarat optik menerusi beberapa saluran yang berbeza-beza, yang masing-masing mempunyai kekangan yang tersendiri telah dipasarkan. Walau bagaimanapun, teknologi tersebut terlalu mahal untuk digunakan pada beberapa aplikasi tertentu. Tujuan utama peranti buatan tangan ini ialah untuk membangunkan pencerai optik berkos rendah menggunakan PMMA-POF bagi aplikasi pelbagai guna. Pengganding disuntik dengan diod pemancar cahaya (LED) berwarna merah dengan panjang gelombang 650 nm bagi menganalisis kecekapan kuasa pengganding. Kecekapan yang diperolehi mencapai sehingga 80% kuasa isyarat optik yang merentasi pencerai optik tersebut. Prestasi bagi pencerai optik buatan tangan ini masih dapat diperbaiki melalui latihan yang berterusan.
Air-dried leaves of both Glycosmis citrifolia and Glycosmis elongata collected from Bogor Botanical Garden, Indonesia were individually extracted with chloroform to give dark viscous extracts after solvent removal. Column chromatographic separation of the extract of G. citrifolia yielded 5(6)-glutene-3α-ol, two sets conformers, (E)-dambullin and (Z)-dambullin, and (E)-methyldambullin and (Z)-methyldambullin. Similar treatment of the extract of G. elongata gave skimmianine and arborinine. The structures of the compounds were elucidated based on spectroscopic data and comparison with published reports.
This paper reports on the preparation of magnetic lumen loaded handsheets from bleached and unbleached mixed tropical hardwood kraft pulps. The lumen coating technique is a physical approach whereby fillers were deposited inside the fibre lumen. In order to produce magnetically responsive fibres, magnetic fillers were loaded into the fibre lumen. The magnetic filler chosen was magnetite which is usually used to make mylar as found in a diskette. Low and high molecular weights of polyacrylamide (PAM) were used as retention aids. The effect of different molecular weight of PAM on filler content in the bleached and unbleached handsheets were studied. The results showed that the amount of fillers deposited in the pulp fibres increased with increasing molecular weight of PAM using both pulps. However the bleached pulps gave better lumen loading than the unbleached when using high molecular weight of PAM.
Precipitated calcium carbonate fillers were loaded into the lumen of bleached mixed tropical hardwood pulp using polyethylenimine (PEI) and alum. Our results indicated that the addition of (PEI) increased the degree of loading of precipitated calcium carbonate (PCC) into the lumen of fibers. The degree of loading also increased with the addition of alum together with PEI. The mechanical strengths of the produced lumen loaded paper increased with the addition of PEI and alum. Meanwhile the mechanical strength without alum had slightly increased the mechanical strengths of the paper. Electron micrographs revealed that the PCC fillers were successfully loaded into the lumen of the fibers.
A study of surface pressure - area (Π-A) isotherms, surface potential (ΔV) and effective dipole moment (μ⊥) of two calix[4]arenes, 5,11,17,23-tetra-tert-butyl-25,27-diethoxycarbonyl methyleneoxy-26,28,dihydroxycalix[4]arene (calixarene I) and 5,17-(3-nitrobenzylideneamino)-11,23-di-tert-butyl-25,27-diethoxycarbonyl methyleneoxy-26,28-dihydroxycalix[4]arene (calixarene II) LB films which have the same lower rim but different upper rim has been carried out. This work used a NIMA Surface Potential (S-POT) sensor attached to an LB trough. Space filling model or Corey, Pauling and Koltun (CPK) precision molecular models have been used to estimate the size and the flexibility of both calix[4]arenes, which has been confirmed by X-Ray analysis in one case. The Π-A-isotherms confirmed that both of the calix[4]arenes form a monolayer film and the orientations of the plane of the calix ring are parallel with the air-water interface. The value of limiting area, (Alim) increases as a result of adding Fe3+ salt in the water subphase. For I, the value increases from 1.28 nm2 to 1.44 nm2 while for II, it increases from 1.70 nm2 to 1.86 nm2. ΔV measurements were performed on a water subphase containing Fe3+ salt in the concentration range 0 – 1.25 × 10–1 mM. ΔV of the compressed monolayer films increased with increasing Fe3+ concentration indicating the presence of Fe3+ salt bound within the calix[4]arenes. Using the ΔV values, the effective dipole moment has been found using the Helmholtz equation.
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.
Amaranthus spinosus Linn. complete plant material was extracted successively by petroleum ether, chloroform, methanol, and water. All the extracts were subjected to in vitro non-enzymatic haemo-glycosylation method, i.e. an oxidation reaction. The degree of haemoglycosylation in the presence of different extracts of Amaranthus spinosus were measured colorimetrically at 520 nm. The preventive effect of haemoglobin glycosylation at the two concentration; 0.5 and 1 mg/mL was estimated as follows: pet. ether; 13.1%, 16.4%, chloroform; 5.7%, 12%, methanol: 36.91%, 56.07% and aqueous: 22.2%, 31.01 %, respectively. The α-tocopheral (Vitamin E) was used as standard.