Displaying publications 1 - 20 of 2561 in total

  1. Ali ?hsan Kadio?ullari, Emin Zeki Ba?kent, Sedat Kele?, Özkan B?ngöl
    Sains Malaysiana, 2015;44:325-336.
    Decision Support Systems (DSS) is widely used to develop spatially explicit forest management plans through the
    integration of spatial parameters. As a part of this study, a simulation-based spatial DSS, the ETÇAPSimülasyon program
    was developed and tested in a case study area. The system has the capability to control the spatial structure of forests
    based on a geodatabase. Geographical Information Systems (GIS) was used to generate the database, using spatial
    parameters including opening size, block size and green-up delay in addition to other attribute data such as the empirical
    yield table and the product assortment table. Based on the simulation technique, a spatial forest management model
    was developed to link strategic planning with tactical planning on a stand base and to present results with a number
    of performance indicators. One important component of the model determined all spatial characteristics with spatial
    parameters and patch descriptions. A stand growth and yield simulation model (BARSM) based on the relationship between
    current and optimal basal area development was also generated to project future stand characteristics and analyze the
    effects of various silvicultural treatments. A number of spatial forest management strategies were developed to generate
    spatially implementable harvest schedules and perform spatial analyses. The forest management concept was enhanced
    by employing a spatial simulation technique to help analyzing the ecosystem structure. Spatial characteristics for an
    on-the-ground forest management plan were then developed. The model was tested in Altınoluk Planning Unit (APU)
    using a spatial simulation technique based on various spatial parameters. The results indicated that the spatial model
    was able to satisfy the spatial restriction requirements of the forest management plan.
  2. Lum CY, Ong LH, ÄŒepic M
    Sains Malaysiana, 2011;40:1123-1127.
    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.
  3. Muhammad aqil fitri rosli, kamalrul azlan azizan, goh hh
    Sains Malaysiana, 2018;47:3069-3075.
    Nepenthes, locally known as ‘periuk kera’ in Malaysia, is a fascinating species due to uniqueness in their morphology
    in having pitcher organ for carnivorous diet. The pitcher plant has been used for cooking traditional delicacies and
    as traditional remedies to treat illness. Hence, this species might possess beneficial health properties. This study
    aimed to compare the antioxidant activity of the pitcher extracts from Nepenthes ampullaria, Nepenthes rafflesiana
    and their hybrid, Nepenthes × hookeriana. The samples were extracted using methanol:chloroform:water (3:1:1)
    via sonication assisted extraction and the extracts were subjected to three different antioxidant assays, namely
    2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing power (FRAP) and total phenolic content (TPC). Extract from N.
    ampullaria exhibited the strongest radical scavenging activity (0.148 ± 0.04 mg/mL) with the highest ferric reducing
    power (0.009 ± 0.003 mg GA/mg dry weight) among the three species, whereas that of N. rafflesiana possessed the
    highest phenolic content (0.057 ± 0.017 mg GA/mg dry weight). However, the antioxidant capacities of the pitcher
    extracts were not significantly different (p>0.05) between the three species and were much lower than the gallic acid
    as a standard reference.
  4. Md. Yeamin Hossain, Md. Mosaddequr Rahman, elgorban M. abdallah
    Sains Malaysiana, 2012;41:803-814.
    The ticto barb Puntius ticto (Hamilton 1822) is a small, indigenous fish species of Bangladesh that is widely distributed in the natural waters of Asian countries. This study describes the relationships between body size, weight, condition (Fulton’s, KF; allometric, KA, KR; and relative weight, WR) and fecundity of the threatened species P. ticto from the Ganges River, northwestern Bangladesh. A total of 24 mature female specimens were collected by the traditional fishing gears from March to August 2006. For each individual, total (TL), fork (FL), standard length (SL), and ovary length (OL)
    were measured by digital slide calipers, while body (BW) and ovary weight (OW) were taken by a digital balance. Total fecundity (FT) of each female was calculated as the number of eggs found in each ovary, whereas relative fecundity (FR) was the number of eggs per gram of fish weight. The results showed that TL of P. ticto varied from 9.10 to 10.80 cm, with calculated mean ± SD as 9.77±0.57 cm. Body weights extended from 14.00 to 24.00 g, with calculated mean ± SD as 17.83±3.39 g. The mean FT was 2586±700 and ranged from 1611 to 4130. BW was more significantly correlated with total fecundity (r2>0.633; p<0.001) than various other body metrics. The results also indicated significant correlation between length-weight (df=22, t-test≥8.86, p<0.001); FT -KF (rs=0.473; p=0.019), FT-KA (rs=0.502; p=0.012), and FT-WR (rs=0.483; p=0.016), but insignificant correlations were found between FT-GSI(rs=0.309; p=0.141) and FR-with various other body metrics. The knowledge of fecundity would be useful to impose adequate regulations for the conservation of this threatened species in the Ganges River and nearby areas of Bangladesh.
  5. Samsiah Jusoh, Fasihuddin Ahmad, Laily B. Din, Zuriati Zakaria
    Sains Malaysiana, 2015;44:1579-1585.
    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.
  6. Nor Azah Mohamad Ali, Ibrahim Jantan, Sri Nurestri Abd. Malek, Zuriati Zakaria
    The chemical compositions of the leaf and bark oils of Xylopia caudata were examined by co-chromatography with authentic samples on a polar capillary column (PEG 20M) and a non polar capillary column (SE-30), GC/MS and further comparison with Kovats Retention Index. The essential oils were mainly made up of monoterpenoids. The major components in both oils were β-pinene, α-pinene, limonene and a-terpineol which collectively represented 90% and 69% of the leaf and bark oils respectively.
    Kandungan kimia minyak pati daun dan kulit kayu Xylopia caudata telah dikaji secara ko-kromatografi dengan sampel tulen di atas turus rerambut polar (PEG 20M) dan turus rerambut kurang polar (SE-30), KG/SJ dan perbandingan dengan Indeks Penahanan Kovats. Sebahagian besar minyak pati tersebut terdiri daripada sebatian monoterpenoid. Komponen utama yang terdapat dalam kedua-dua minyak pati tersebut adalah β-pinena, α-pinena, limonena dan a-terpineol yang mewakili 90% dan 69% daripada minyak pati daun dan kulit kayu masing-masing.
  7. Fasihuddin B.A., Laily B. Din, Zuriati Zakaria
    Three compounds were isolated and characterized from the roots of Goniothalamus woodii. Based on their spectroscopic data, the compounds were identified as goniothalamin, 5-acetoxygoniothalamin and goniotriol.
    Tiga sebatian telah dipisahkan dan dicamkan daripada akar Goniothalamus woodii. Berdasarkan dari data spektroskopi, sebatian telah dikenalpasti sebagai goniotalamin, 5-asetoksigoniotalamin dan goniotriol.
  8. Abdul Rahim Samsudin, Umar Hamzah, Zuraidah Ramli
    Sains Malaysiana, 2007;36:159-163.
    An integrated geophysical study was conducted to investigate the subsurface regional structure and the presence of a Quaternary sedimentary basin in the Olak Lempit - Banting area of Selangor, Malaysia. A regional gravity survey and the high resolution reflection seismic were employed to determine the thickness and areal distribution of the alluvial sedimentary basin as well as to investigate the depth and topography of the bedrock in the study area. The sedimentary basin hosts one of the most important coastal alluvial aquifer which was used to cater the shortage of domestic water supply during the worst water crisis that hit the state of Selangor in 1998. The surface geological map shows that in general 70% of the study area is covered by Quaternary deposits of Beruas, Gula and Simpang Formations which overlie the sedimentary bedrock of Kenny Hill Formation. The Beruas Formation consists of mainly clay, sandy clay and peat of Holocene fluviatile-estuarine deposits, whereas the Gula Formation represents Holocene marine to estuarine sediments which mostly consists of clay and minor sand. The Simpang Formation (Pleistocene) is a continental deposit comprising of gravel, sand, clay and silt. The underlying Kenny Hill Formation consists of a monotonous sequence of interbedded shales, mudstones and sandstones. The rock is Carbonaceous in age and it forms an undulating surface topography in the eastern part of the study area. A total of 121 gravity stations were established using a La Coste & Romberg gravity meter and the elevations of most of the stations were determined barometrically using Tiernan-Wallace altimeters. The high resolution seismic reflection using the common mid point (CMP) or roll along technique was carried out using a 24 channel signal enhancement seismograph and high frequency geophones. A total length of about 1.7 km stacked seismic section has been acquired in this survey and a nearby borehole data was used for interpretation. A relative Bouguer anomaly map shows an elongated zone of low gravity anomaly trending approximately NW-SE which is interpreted to be the deposition center of the Quaternary basin. The interpreted gravity profiles running across the central area of the study area show that the basin has thickness varies from tenth to several hundred meters with maximum depth to bedrock of about 275m. A gravity profile which passes through the eastern edge of the basin was modeled with depth to bedrock of about 178m below ground which agrees very well with those obtained from the interpreted seicmic section and borehole data. The stacked seismic section shows several high amplitude parallel to sub-parallel reflection overlying discontinuos and low reflection pattern. Reflections on the eastern part of the section is much shallower than the one observed on the western part which clearly indicates the presence of basinal structure with a total interpreted depth to bedrock of about 200 meters.
  9. Nor Bakhiah Baharim, Ismail Yusoff, Wan Zakaria Wan Muhd Tahir, Muhamad Askari, Zainudin Othman, Mohamed Roseli Zainal Abidin, et al.
    Sains Malaysiana, 2016;45:43-53.
    The relationship between heavy metal and trophic properties in polymictic lake at Sembrong Lake, Peninsular Malaysia was assessed. Sixteen parameters, including heavy metals and trophic parameters were monitored. pH, temperature, dissolved oxygen and heavy metals level changes significantly influenced by the dynamic of polymictic mixing pattern. The mean concentrations of heavy metals in the reservoir decreased in the following order: Fe > Mn > Zn > Cu > As > Pb. The result showed that this polymictic lake is being threatened by cultural eutrophication with TSI value range from 72.40 to 80.41 and classified as a hypereutrophic lake. The levels of heavy metal pollution in the reservoir range from slightly polluted to polluted. Factor analysis was performed to determine the relationship between heavy metals and trophic parameters. Five factors were responsible for data structure and explained the 83% of total variance. These factors differentiate each group of parameters according to their common characteristics. Photosynthesis, respiration and redox processes were main factors contributing to the variability of both properties.
  10. Kok H, Nor Azwady A, Loh K, Muskhazli M, Zulkifli S
    Sains Malaysiana, 2014;43:169-173.
    The present study was carried out to determine the optimal stocking density for culturing tropical soil dwelling earthworm, Pontoscolex corethrurus. F1 generation earthworms were cultured in four different stocking densities of 1, 4, 7 and 10 worms per vessel, corresponding to field densities of 50, 200, 350 and 500 individuals per m2. Earthworms were kept under laboratory conditions (25±2°C and 25% moisture) for the 14 weeks study period. The results showed that at higher earthworm densities (>350 individuals per m2), the earthworm growth was slower and sexual maturation was delayed as compared with their counterparts in lower stocking density. With the high survival rate and parthenogenetic reproduction mode, P. corethrurus could potentially be used as tropical soil rehabilitation agent.
  11. Ahmad Fikri Abdul Karim, Hanafi Ismail, Zulkifli Mohamad Ariff
    Sains Malaysiana, 2018;47:2163-2169.
    This research was carried out to study the effects of kenaf loading and alkaline treatment on tensile properties, density,
    thermal and morphological properties of kenaf filled natural rubber latex foam (NRLF). Samples were prepared using a
    Dunlop method. From the results, increasing loading of kenaf reduced the tensile strength and elongation at break for
    both samples, treated and untreated kenaf filled NRLF. Meanwhile, modulus at 100% elongation and density increased
    with an increased in kenaf loading. Samples with treated kenaf showed higher tensile strength, modulus at 100%
    elongation and density but low in elongation at break as compared with samples with untreated kenaf. Thermal study
    by using thermogravimetric analysis (TGA) showed that thermal stability reduced with increased in kenaf loading for
    both samples. Samples with treated kenaf have higher thermal stability compared with samples of untreated kenaf. The
    filler-matrix interaction and the pores size variation of both samples was clearly seen in the micrograph images by using
    scanning electron microscope (SEM).
  12. Noraswana Nor Faiz, Kamal Roslan Mohamed, Ramlan Omar, Zulkhairi Akmar Ahmad
    Sains Malaysiana, 2017;46:1709-1719.
    Suatu kajian telah dijalankan untuk menentukan kepelbagaian dan kelimpahan foraminifera di sedimen permukaan sekitar delta Sungai Kelantan memandangkan kajian foraminifera terutamanya di perairan marin Malaysia amat kurang. Sejumlah 22 stesen daripada dua garisan transek telah ditentukan sebagai kawasan persampelan. Sebanyak 10,317 individu foraminifera yang terdiri daripada 27 famili, 34 genus dan 55 spesies telah ditemui di kawasan kajian. Secara keseluruhannya, famili Hauerinidae mencatatkan kepelbagaian spesies tertinggi (10 spesies) manakala famili paling dominan dengan jumlah individu tertinggi ialah Rotaliidae (26.14%). Spesies dominan dan paling melimpah di kawasan kajian ialah Asterorotalia pulchella (17.24%) dan Operculina ammonoides (10.19%). Indeks kepelbagaian spesies, H’ yang dicatatkan ialah antara 0.5 hingga 3.1 manakala indeks kekayaan spesies, α adalah antara 1.5 hingga 7.9. Kelimpahan dan kepelbagaian spesies tertinggi (α=7.9, H’=3.1) dicatatkan pada stesen 21 yang terletak di laut terbuka dengan kedalaman air sebanyak 36.8 m dan bersaliniti 32.2 ppt mendekati laut normal. Nilai H’ dan α terendah dicatatkan pada stesen yang berdekatan dengan muara sungai yang cetek dan bersaliniti lebih rendah. Secara keseluruhannya, nilai indeks kepelbagaian yang dicatatkan di kawasan kajian adalah menepati persekitaran marin berair cetek. Kesimpulannya, kepelbagaian dan kelimpahan foraminifera di kawasan kajian dipengaruhi oleh kedalaman dan saliniti air.
  13. Lee KM, Abdul Halim Abdullah, Mohd Zobir Hussein, Zulkarnain Zainal
    Sains Malaysiana, 2014;43:437-441.
    ZnO/γ-Fe2O3 catalysts were fabricated via a simple precipitation route using zinc acetate and iron acetate as the precursors and ammonia as the precipitant. The resulted nanocatalysts were subjected to heat treatment at 450°C for 2 h. The characteristics of the nanocomposite were investigated by various characterization techniques. The synthesized nanocomposite has an average particle size of 13 nm and a surface area of 17 m2/g. The photocatalytic activity of ZnO/γ- Fe2O3 nanocomposite was evaluated by photodegrading 2,4-dichlorophenoxyacetic acid (2,4-D) under UV irradiation. The results showed that ZnO/γ-Fe2O3 nanocomposite exhibited enhanced photoactivity compared to pure ZnO with almost 20% increment within 4 h of reaction time. The result indicated the applicability of ZnO/γ-Fe2O3 nanocomposite to be used as photocatalyst in removing organic pollutants in wastewater.
  14. Hamidinezhad H, Yussof Wahab, Sumpono I, Zulkafli Othaman
    Silicon nanowires (SiNWs) have been synthesized by plasma enhanced chemical vapor deposition (PECVD) at different power for generation of plasma and different flow rate of silane gas. Silane (10% SiH4 in Ar) gas with flow rate ranging between 6-15 standard cubic centimeter per minute(sccm) were employed as the source and gold colloid as the catalyst. A p-type Si (100) wafer was used as substrate in this experiment and the substrate’s temperature was 370°C.The plasma power range was 12-17 watts. The grown silicon nanowires were analyzed using field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDX). FESEM results show that some silicon nanowires are cone like and some of them are cylindrical. The EDX result revealed that the existence of silicon and oxygen elements in the nanowires. The silicon nanowires obtained have different diameters and lengths and the SiNWs consist of silicon core which are surrounded by oxide sheath. It has been found that the plasma power and flow rate of the silane gas influence the size of silicon nananowires growth by PECVD. The diameter of wires decreased from 140 nm to 80 nm averagely when plasma power was increased from 12 to 17 watts. The diameter also increased about 90 nm to 150 nm when the flow rate of silane gas is increased from 6 to 15 sccm.
  15. Yussof Wahab, Hamidinezhad H, Zulkafli Othaman
    Sains Malaysiana, 2013;42:183-186.
    Silicon nanowires (SiNWs) with diameter of about a few nanometers and length of 3 μm on silicon wafers were synthesized by very high frequency plasma enhanced chemical vapor deposition. Scanning electron microscopy (SEM) observations showed that the silicon nanowires were grown randomly and energy-dispersive X-ray spectroscopy analysis indicates that the nanowires have the composition of Si, Au and O elements. The SiNWs were characterized by high resolution transmission electron microscopy (HRTEM) and Raman spectroscopy. SEM micrographs displayed SiNWs that are needle-like with a diameter ranged from 30 nm at the top to 100 nm at the bottom of the wire and have length a few of micrometers. In addition, HRTEM showed that SiNWs consist of crystalline silicon core and amorphous silica layer.
  16. Siti Afida I., Razmah G., Zulina A. M.
    Sains Malaysiana, 2016;45:949-954.
    The concern on the widespread use of surfactants is increasing worldwide as they can be potential toxicants by polluting
    the environment, with the damage formed depending on their exposure and persistence in the ecosystem. This paper
    was intended to evaluate the biodegradability of palm-based surfactant, MES, in order to establish their environmental
    friendliness. The respirometric method was used to monitor the biodegradation of various homologues of MES over 28
    days as described in the OECD 301F Manometric respirometry test method. The results showed all the MES homologues
    tested were readily biodegradable with percentage of biodegradation achieved for C12, C14 and C16 MES was 73%
    within 6 days, 66% within 8 days and 63% within 16 days, respectively, while linear alkylbenzene sulphonates (LAS)
    sample 60% biodegraded within 8 days. From the results, it can be concluded that the longer the carbon chain length, the
    lower is the biodegradability of MES as the microorganisms took longer time to degrade a longer chain surfactant. Other
    than that, the presence of aromatic structure in LAS may also extend the biodegradation process. The use of palm-based
    surfactant, i.e. MES, is more environmental friendly and can be used as an alternative to petroleum-based surfactant to
    reduce adverse environmental effects of surfactant on ecosystem.
  17. M. Hamid Ch, M. Ashraf, Qudsia Hamid, Syed Mansoor Sarwar, Zulfiqar Ahmad Saqib
    Sains Malaysiana, 2017;46:413-420.
    Remote Sensing (RS) and Geographical Information Systems (GIS) are widely used for change detection in rivers caused
    by erosion and accretion. Digital image processing techniques and GIS analysis capabilities are used for detecting
    temporal variations of erosion and accretion characteristics between the years 1999 and 2011 in a 40 km long Marala
    Alexandria reach of River Chenab. Landsat satellite images for the years 1999, 2007 and 2011 were processed to analyze
    the river channel migration, changes in the river width and the rate of erosion and accretion. Analyses showed that the
    right bank was under erosion in both time spans, however high rate of deposition is exhibited in middle reaches. The
    maximum erosion was 1569843 m2
    and 1486160 m2
    along the right bank at a distance of 24-28 km downstream of the
    Marala barrage in the time span of 1999-2007 and 2007-2011, respectively. Along right bank mainly there is trend of
    accretion but erosion is much greater between 20 and 28 km reach. Maximum accretion was 5144584 m2
    from 1999-2007
    and 2950110 m2
    from 2007-2011 on the right bank downstream of the Marala Barrage. The derived results of channel
    migration were validated by comparing with SRTM data to assess the accuracy of image classification. Integration of remote
    sensing data with GIS is efficient and economical technique to assess land losses and channel changes in large rivers.
  18. Muhammad Rendana, Sahibin Abdul Rahim, Wan Mohd Razi Idris, Tukimat Lihan, Zulfahmi Ali Rahman
    Sains Malaysiana, 2017;46:537-543.
    Over many years, forested land transformation into urban, agriculture and mining areas within Tasik Chini Catchment become more intense. These activities have negatively affected the catchment through soil erosion and increased the amount of sediments that deposited into the lake. Hence, the present study aimed to estimate soil erosion risk within Tasik Chini Catchment integrating the Revised Universal Soil Loss Equation (RUSLE) model and remotely sensed geospatial data. The multispectral imagery from LANDSAT 8 was used to provide up to date information on land cover within the catchment. The result shows the majority of Tasik Chini Catchment is classified at very low class (< 10 ton ha−1 yr−1) about 4835.34 ha (92.38%), followed by the low class (10-50 ton ha−1 yr−1) with total area of 175.47 ha (3.35%), moderate high class (50-100 ton ha−1 yr−1) with total area of 65.11 ha (1.24%), high class (100-150 ton ha−1 yr−1) with total area of 38.37 ha (0.73%) and very high class (> 150 ton ha−1 yr−1) with total area of 120.04 ha (2.30%). Tasik Chini Catchment is very susceptible to soil erosion especially on northwest and southeast regions, where the main sources of soil loss come from the agricultural, new settlements and mining activities. To conclude, the estimation of soil erosion model using remotely sensed data can be used to build sustainable development strategy within Tasik Chini Catchment in the future.
  19. Maman Hermana, Hammad Hazim Mohd Azhar, Zuhar Zahir Tuan Harith
    Sains Malaysiana, 2012;41:953-959.
    This paper presents the improvement of quality factor (Q) estimation using shift frequency method. A new method was developed based on two previous methods; peak frequency shift (PFS) method and centroid frequency shift (CFS) method. The proposed algorithm has been tested to gauge its performance using three different scenarios; Q variation, travel
    time variation, and signal to noise ratio (SNR) variation. The test was performed using the Ricker wavelet with random noise included. Based on the results obtained, it can be concluded that the new proposed method was able to improve Q estimation using shift frequency method. This method can also be implemented in the low and high Q condition, shallow and deep wavelet targets and in the low and high SNR conditions of seismic data. The limitations in the PFS and CFS methods can be reduced by this method.
  20. Shahrom Mahmud, Zubir Din
    Sains Malaysiana, 2014;43:261-265.
    A zinc oxide (ZnO) pilot plant furnace was used to synthesize ZnO nanoparticles at very high capacities in a range of 1-4 t/month. The 4-t custom-designed furnace was used to synthesize ZnO particles possessing primary nanoparticles resembling rods and grains. At a combustion temperature of 1000-1300°C, zinc vapour was oxidized into ZnO powder in order to produce granular ZnO (ZG) particles. By blowing air into the combustion chamber, ZnO nanorods (ZR) were produced. The ZR specimen exhibited higher XRD intensities, stronger photocatalysis and higher electrical resistance compared to that of ZG sample. However, the ZR sample showed a stronger toxicity to marine phytoplankton, Isochrysis galbana, by starting to inhibit cell growth at 8 mg/L ZnO concentration in seawater whereas ZG sample started showing growth inhibition at a higher ZnO concentration of 32 mg/L. The toxicity of ZnO primary nanoparticles was probably attributed to the dissolution, release and uptake of free zinc ions especially for the case of the higher surface area of ZR particles that exhibited relatively higher zinc concentration on the particle surface, based on the elemental mapping of the electron spectroscopy imaging results.
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