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Effects of the nitric acid concentrations on the etching process, structural and optical properties of porous zinc oxide thin films

C.G. Ching, Leonard Lu, C.I. Ang, P.K. Ooi, S.S. Ng, Z. Hassan, et al.

Sains Malaysiana, 2013;42:1327-1332.

The present study reports on the fabrication of porous zinc oxide by wet chemical etching. ZnO thin films were deposited via radio-frequency magnetron sputtering on p-type silicon with (111) preferred orientation. The etchants used in the present work were 0.1% and 1.0% nitric acid (HNO3) solutions. ZnO were etched at various times and were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) spectroscopy to allow the examination of their structural and optical properties. The XRD results revealed that the intensity of ZnO(002) decreased when the thin films were etched in varying HNO3 concentrations over different periods of time. The above observation is attributed to the dissolution of the ZnO(002). The SEM images showed that the thickness of the ZnO layers decreased over the etching time, which resulted from the isotropic etching by the HNO3 solution. The PL emission intensity initially increased with increasing etching time. However, with further etching of the samples, the PL spectra showed a decreasing trend in intensity as a result of the decrease in the surface-to-volume ratio. All results lead to the conclusion that 1.0% HNO3 has the capability to change the ZnO surface significantly.

Matched MeSH terms: Microscopy, Electron, Scanning
Controlled-growth of ZnO nanowires with different processing temperature

Yap CC, Muhammad Yahaya, Muhamad Mat Salleh, Dee CF

Sains Malaysiana, 2008;37:233-237.

ZnO nanowires have been synthesized using a catalyst-free carbothermal reduction approach on SiO2-coated Si substrates in a flowing nitrogen atmosphere with a mixture of ZnO and graphite as reactants. The collected ZnO nanowires have been characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and photoluminescence spectroscopy. Controlled growth of the ZnO nanowires was achieved by manipulating the reactants heating temperature from 700 to 1000 oC. It was found that the optimum temperature to synthesize high density and long ZnO nanowires was about 800 0C. The possible growth mechanism of ZnO nanowires is also proposed.

Matched MeSH terms: Microscopy, Electron, Scanning
Comparative studies on plasticized and unplasticized polyacrylonitrile (PAN) polymer electrolytes containing lithium and sodium salts

Md. Isa K, Othman L, Osman Z

Sains Malaysiana, 2011;40:1179-1186.

Polymer electrolytes based on polyacrylonitrile (PAN) containing inorganic salts; lithium triflate (LiCF3SO3) and sodium triflate (NaCF3SO3) and ethylene carbonate (EC) as plasticizer were prepared using solvent casting technique. In this study, five systems of plasticized and unplasticized polymer electrolyte films i.e. PAN-EC, PAN-LiCF3SO3, PAN-NaCF3SO3 PAN-EC-LiCF3SO3 and PAN-EC-NaCF3SO3 systems have been prepared. The structural and morphological properties of the films were studied using infrared spectroscopy and scanning electron microscopy (SEM) while the conductivity study was done by using impedance spectroscopy. The infrared results revealed that interaction had taken place between the nitrogen atoms of PAN and Li+ and Na+ ions from the salts. SEM micrographs showed that the plasticized film, PAN-EC-NaCF3SO3 has bigger pores than PAN-EC-LiCF3SO3 film resulting in the film containing NaCF3SO3 salt being more conductive. On addition of salts and plasticizer, the conductivity of pure PAN increases to three orders of magnitude. The plasticized film containing NaCF3SO3 salt has a higher conductivity compared to that containing LiCF3SO3 salt. This result showed that the interaction between Li+-ion and the nitrogen atom of PAN was stronger than that of Na+-ion. The conductivity-temperature dependence of the highest conducting film from each system follows Arrhenius equation in the temperature range of 303 to 353 K. The conductivity-pressure study in the range of 0.01 - 0.09 MPa showed that the conductivity decreased when pressure was increased. This can be explained in term of free volume model.

Matched MeSH terms: Microscopy, Electron, Scanning
Fulltext Nonprescription Bleaching versus Home Bleaching with Professional Prescriptions: Which One is Safer? A Comprehensive Review of Color Changes and Their Side Effects on Human Enamel

Omar F, Ab-Ghani Z, Rahman NA, Halim MS

Eur J Dent, 2019 Oct;13(4):589-598.
PMID: 31891975 DOI: 10.1055/s-0039-1700659

OBJECTIVES: This study evaluates the efficacy and safety of the professionally prescribed and nonprescription over-the-counter (OTC) bleaching agents.
MATERIALS AND: METHODS: Extracted human upper central incisors were prepared and stained with red wine for 14 days before being subjected to four different bleaching agents: professionally prescribed opalescence PF 15%, VOCO Perfect Bleach 10%, nonprescription OTC Crest 3D Whitestrips, and Whitelight Teeth Whitening System. Colorimetric measurement was performed with Vita Easyshade Handheld Spectrophotometer, enamel surface microhardness measured using Vickers Hardness machine, and surface roughness was evaluated with profilometer, before and after bleaching. Scanning electron microscope (SEM) evaluation and atomic force microscopy were conducted postbleaching.
STATISTICAL ANALYSIS: The data were analyzed with t-test, two-way ANOVA, one-way ANOVA, and Turkey's test at a significance level of 5%.
RESULTS: All bleaching products have the same efficacy to whiten stained enamel. Opalescence PF 15% showed significant increase in the microhardness (92.69 ± 68.316). All groups demonstrated significant increase in surface roughness (p < 0.05). SEM evaluation showed that Opalescence PF 15% resulted in same microscopic appearance as unbleached enamel, while VOCO Perfect Bleach 10%, Whitelight Teeth Whitening System and Crest 3D Whitestrips demonstrated mild to moderate irregularities and accentuated irregularities, respectively.
CONCLUSION: Professionally prescribed bleaching agent of Opalescence PF 15% is effective tin whitening the teeth, while the other bleaching products may be effective but also have deleterious effects on the enamel.

Matched MeSH terms: Microscopy, Electron, Scanning
Fulltext Application of Biochar Derived From Pyrolysis of Waste Fiberboard on Tetracycline Adsorption in Aqueous Solution

Xu D, Gao Y, Lin Z, Gao W, Zhang H, Karnowo K, et al.

Front Chem, 2019;7:943.
PMID: 32117859 DOI: 10.3389/fchem.2019.00943

In this study, biochars derived from waste fiberboard biomass were applied in tetracycline (TC) removal in aqueous solution. Biochar samples were prepared by slow pyrolysis at 300, 500, and 800°C, and were characterized by ultimate analysis, Fourier transform infrared (FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), etc. The effects of ionic strength (0-1.0 mol/L of NaCl), initial TC concentration (2.5-60 ppm), biochar dosage (1.5-2.5 g/L), and initial pH (2-10) were systemically determined. The results present that biochar prepared at 800°C (BC800) generally possesses the highest aromatization degree and surface area with abundant pyridinic N (N-6) and accordingly shows a better removal efficiency (68.6%) than the other two biochar samples. Adsorption isotherm data were better fitted by the Freundlich model (R2 is 0.94) than the Langmuir model (R2 is 0.85). Thermodynamic study showed that the adsorption process is endothermic and mainly physical in nature with the values of ΔH0 being 48.0 kJ/mol, ΔS0 being 157.1 J/mol/K, and ΔG0 varying from 1.02 to -2.14 kJ/mol. The graphite-like structure in biochar enables the π-π interactions with a ring structure in the TC molecule, which, together with the N-6 acting as electron donor, is the main driving force of the adsorption process.

Matched MeSH terms: Microscopy, Electron, Scanning
Fulltext Cryopreservation of oil palm (Elaeis guineensis Jacq.) polyembryoids via encapsulation-desiccation

Palanyandy SR, Gantait S, Subramaniam S, Sinniah UR

3 Biotech, 2020 Jan;10(1):9.
PMID: 31850156 DOI: 10.1007/s13205-019-1997-9

The current report assesses the efficiency of encapsulation-desiccation protocol to cryopreserve oil palm (Elaeis guineensis Jacq.) polyembryoids. Specifically identified polyembryoids, comprising of haustorium and torpedo-shaped structures, were encapsulated [comprising 3% (w/v) sodium alginate and 100 mM CaCl2]. Calcium alginate-encapsulated and sucrose-precultured polyembryoids were subjected to different spans of desiccation in a laminar air-flow cabinet, followed by freezing in liquid nitrogen. The effect of sucrose preculture (with gradual exposure to 0.3, 0.5, 0.75 and 1 M for 7 days) and dehydration periods (0-10 h) under sterile air-flow on post-freezing survival and regrowth of encapsulated polyembryoids were studied. Cryopreserved and thawed polyembryoids (initially precultured in sucrose, followed by 9 h air-desiccated to 23.3% moisture content) displayed the highest survival percentage (73.3%) and regeneration (of shoot, root and secondary somatic embryo) on Murashige and Skoog regrowth medium containing sucrose (0.3-1 M) and 0.2 mg/l 2,4-dichlorophenoxy acetic acid. In addition, ultrastructural study using scanning electron microscopy exhibited successful revival of cryopreserved polyembryoids, owing to retention of cellular membrane stability through optimized and protected (encapsulated) desiccation. The present study thus substantiates the potential of this encapsulation-desiccation procedure in cryopreservation of oil palm polyembryoids for long-term conservation programs.

Matched MeSH terms: Microscopy, Electron, Scanning
Stability improvement of algal-alginate beads by zeolite molecular sieves 13X

Emami Moghaddam SA, Harun R, Mokhtar MN, Zakaria R

Int J Biol Macromol, 2019 Jul 01;132:592-599.
PMID: 30922914 DOI: 10.1016/j.ijbiomac.2019.03.191

This research aimed to improve the stability of Chlorella-Alginate Beads (CABs) by zeolite molecular sieves 13X. Dissolution time of synthesized Zeolite-Algal-Alginate Beads (ZABs) in a chelating agent revealed a significant improvement on the beads stability (78.5 ± 0.5 min) compared to the control beads (51.5 ± 0.5 min) under the optimum conditions of zeolite/alginate (1.5:1), pH 5 and 2% of beads. Monitoring cell growth during 5 days of incubation showed good biocompatibility of zeolite 13X. Scanning electron microscopy (SEM) indicated rough surface and spherical shapes of ZABs. Energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FTIR) of ZABs confirmed the presence of zeolite 13X within the matrix. The zeta potential value of ZABs indicated that the beads were relatively stable. The findings of this research showed that zeolite molecular sieves 13X have the potential to improve the stability of algal-alginate beads compared to common beads.

Matched MeSH terms: Microscopy, Electron, Scanning
Enhancement of high temperature performance of cement blocks via CO2 curing

Meng Y, Ling TC, Mo KH, Tian W

Sci Total Environ, 2019 Jun 25;671:827-837.
PMID: 30947055 DOI: 10.1016/j.scitotenv.2019.03.411

Carbonation for the curing of cement-based materials has been gaining increased attention in recent years, especially in light of emerging initiatives to reduce carbon dioxide (CO2) emissions. Carbonation method or CO2 curing is founded on the basis of the reaction between CO2 and cement products to form thermally stable and denser carbonate, which not only improves the physical and mechanical properties of cement-based materials, but also has the ability to utilize and store CO2 safely and permanently. This study aims to assess the effect of CO2 curing technology on the high-temperatures performance of cement blocks. Upon molding, dry-mix cement blocks were cured under statically accelerated carbonation condition (20% CO2 concentration with 70% relative humidity) for 28 days, followed by exposure to elevated temperatures of 300 °C to 800 °C in order to comprehensively study the principal phase changes and decompositions of cement hydrates. The results indicated that CO2 curing improved the performance of cement blocks, such as enhancement in the residual compressive strength and reducing the sorptivity. At 600 °C, the scanning electron microscopy (SEM) revealed a denser microstructure while thermal analisis and X-ray diffraction (XRD) analysis also clearly demonstrated that higher amounts of calcium carbonate were present in the cement blocks after CO2 curing, suggesting better high-temperature performance compared to natural cured cement blocks. In general, an improved high-temperature performance, specifically at 600 °C of the dry-mixed cement blocks was demonstrated by adopting the CO2 curing technology. This confirms the potential of utilizing CO2 curing technology in not only improving quality of cement blocks, new avenue for storing of CO2 in construction material can be realized at the same time.

Matched MeSH terms: Microscopy, Electron, Scanning
Fulltext Zinc/Aluminium⁻Quinclorac Layered Nanocomposite Modified Multi-Walled Carbon Nanotube Paste Electrode for Electrochemical Determination of Bisphenol A

Zainul R, Abd Azis N, Md Isa I, Hashim N, Ahmad MS, Saidin MI, et al.

Sensors (Basel), 2019 Feb 22;19(4).
PMID: 30813385 DOI: 10.3390/s19040941

This paper presents the application of zinc/aluminium-layered double hydroxide-quinclorac (Zn/Al-LDH-QC) as a modifier of multiwalled carbon nanotubes (MWCNT) paste electrode for the determination of bisphenol A (BPA). The Zn/Al-LDH-QC/MWCNT morphology was examined by a transmission electron microscope and a scanning electron microscope. Electrochemical impedance spectroscopy was utilized to investigate the electrode interfacial properties. The electrochemical responses of the modified electrode towards BPA were thoroughly evaluated by using square-wave voltammetry technique. The electrode demonstrated three linear plots of BPA concentrations from 3.0 × 10-8⁻7.0 × 10-7 M (R² = 0.9876), 1.0 × 10-6⁻1.0 × 10-5 M (R² = 0.9836) and 3.0 × 10-5⁻3.0 × 10-4 M (R² = 0.9827) with a limit of detection of 4.4 × 10-9 M. The electrode also demonstrated good reproducibility and stability up to one month. The presence of several metal ions and organic did not affect the electrochemical response of BPA. The electrode is also applicable for BPA determination in baby bottle and mineral water samples with a range of recovery between 98.22% and 101.02%.

Matched MeSH terms: Microscopy, Electron, Scanning
Fulltext Unveiling high specific energy supercapacitor from layer-by-layer assembled polypyrrole/graphene oxide|polypyrrole/manganese oxide electrode material

Kulandaivalu S, Suhaimi N, Sulaiman Y

Sci Rep, 2019 Mar 20;9(1):4884.
PMID: 30894621 DOI: 10.1038/s41598-019-41203-3

A novel layer-by-layer (LBL) based electrode material for supercapacitor consists of polypyrrole/graphene oxide and polypyrrole/manganese oxide (PPy/GO|PPy/MnO2) has prepared by electrochemical deposition. The formation of LBL assembled nanocomposite is confirmed by Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray diffraction. The field emission scanning electron microscopy images clearly showed that PPy/MnO2 was uniformly coated on PPy/GO. The PPy/GO|PPy/MnO2 symmetrical supercapacitor has revealed outstanding supercapacitive performance with a high specific capacitance of 786.6 F/g, an exceptionally high specific energy of 52.3 Wh/kg at a specific power of 1392.9 W/kg and preserve a good cycling stability over 1000 cycles. It is certain that PPy/GO|PPy/MnO2 has an extraordinary perspective as an electrode for future supercapacitor developments. This finding contributes to a significant impact on the evolution of electrochemical supercapacitor.

Matched MeSH terms: Microscopy, Electron, Scanning
Identification, pathogenicity and histopathology of Colletotrichum sansevieriae causing anthracnose of Sansevieria trifasciata in Malaysia

Kee YJ, Zakaria L, Mohd MH

J Appl Microbiol, 2020 Sep;129(3):626-636.
PMID: 32167647 DOI: 10.1111/jam.14640

AIMS: To characterize causal pathogen of Sansevieria trifasciata anthracnose through morphology and molecular analysis; to evaluate the host range of the pathogen; and to explicate the infection process by the pathogen histopathologically.
METHODS AND RESULTS: Symptomatic leaves of S. trifasciata were collected from five states in Malaysia. The causal pathogen was isolated and identified for the first time in Malaysia as C. sansevieriae based on morphological and multi-gene phylogenetic analyses using ITS, TUB2 and GAPDH sequences. Pathogenicity tests were conducted on different hosts. Colletotrichum sansevieriae was not pathogenic towards S. cylindrica, S. masoniana, Furcraea foetida, Chlorophytum comosum, Aloe vera and Gasteria carinata, confirming the exceptionally high host specificity for a species of Colletotrichum. Histopathology was performed using light microscope and scanning electron microscopy to study the infection process of C. sansevieriae on S. trifasciata. Colonization of host leaves by the pathogen was observed 2 days after inoculation.
CONCLUSIONS: Colletotrichum sansevieriae caused anthracnose of S. trifasciata in Malaysia. It is a host-specific pathogen and colonized the host intracellularly.
SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report of C. sansevieriae causing anthracnose of S. trifasciata in Malaysia. The host range test and understanding of the infection process will provide better understanding of the host-pathogen relationship and beneficial for effective disease management.

Matched MeSH terms: Microscopy, Electron, Scanning
Fulltext Filler-Modified Castor Oil-Based Polyurethane Foam for the Removal of Aqueous Heavy Metals Detected Using Laser-Induced Breakdown Spectroscopy (LIBS) Technique

Iqhrammullah M, Marlina, Hedwig R, Karnadi I, Kurniawan KH, Olaiya NG, et al.

Polymers (Basel), 2020 Apr 13;12(4).
PMID: 32294999 DOI: 10.3390/polym12040903

The use of polymeric material in heavy metal removal from wastewater is trending. Heavy metal removal from wastewater of the industrial process is of utmost importance in green/sustainable manufacturing. Production of absorbent materials from a natural source for industrial wastewater has been on the increase. In this research, polyurethane foam (PUF), an adsorbent used by industries to adsorb heavy metal from wastewater, was prepared from a renewable source. Castor oil-based polyurethane foam (COPUF) was produced and modified for improved adsorption performance using fillers, analyzed with laser-induced breakdown spectroscopy (LIBS). The fillers (zeolite, bentonite, and activated carbon) were added to the COPUF matrix allowing the modification on its surface morphology and charge. The materials were characterized using Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), and thermal gravimetry analysis (TGA), while their adsorption performance was studied by comparing the LIBS spectra. The bentonite-modified COPUF (B/COPUF) gave the highest value of the normalized Pb I (405.7 nm) line intensity (2.3), followed by zeolite-modified COPUF (Z/COPUF) (1.9), and activated carbon-modified COPUF (AC/COPUF) (0.2), which indicates the adsorption performance of Pb2+ on the respective materials. The heavy metal ions' adsorption on the B/COPUF dominantly resulted from the electrostatic attraction. This study demonstrated the potential use of B/COPUF in adsorption and LIBS quantitative analysis of aqueous heavy metal ions.

Matched MeSH terms: Microscopy, Electron, Scanning
Characteristics and performance of a mesoporous cerium-aluminum-silver mixed oxide for removal of methyl Violet Dye

Phatai P, Srisomang R

Sains Malaysiana, 2016;45:1477-1485.

In this study, the adsorption efficiency of methyl violet (MV) dye onto Ce0.3Al0.7 and Ce0.3Al0.7Agx (x = 0.1, 0.3 & 0.5) mixed oxides was investigated. The properties of mixed oxide were determined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), N2 adsorption-desorption isotherm, diffuse reflectance UV-vis spectroscopy (UV-vis DRS) and X-ray absorption near edge structure (XANES). Characterization showed that synthesized mixed oxide with fluorite has a pure cubic structure of a mesoporous nature and a small grain size with rough surface. Batch adsorption experiments were used to study parameters including contact time and initial dye concentration. The results showed that these parameters affected the degree of MV dye adsorption. The dye adsorption of mixed oxides attained equilibrium at 120 min. The equilibrium adsorption data were analyzed using Langmuir, Freundlich and Temkin isotherms. The adsorption behavior of MV dye onto Ce0.3Al0.7 was found to follow the Langmuir isotherm (R2 = 0.9951), providing a maximum monolayer adsorptive capacity of 2.35 mg/g. Alternatively, the adsorption of MV dye onto Ce0.3Al0.7Ag0.1 (R2 = 0.7839), Ce0.3Al0.7Ag0.3 (R2 = 0.9301) and Ce0.3Al0.7Ag0.5 (R2 = 0.9396) followed the Freundlich isotherm. The possible adsorption mechanisms of MV dyes onto the Ce0.3Al0.7 and Ce0.3Al0.7Agx were also discussed.

Matched MeSH terms: Microscopy, Electron, Scanning
Anticorrosive properties of nano silicate from paddy husk in salt medium

Norinsan Kamil Othman, Solhan Yahya, Denni Asra Awizar

Sains Malaysiana, 2016;45:1253-1258.

Anticorrosive properties of nano silicate from paddy husk in salt medium was investigated via weight loss method, Tafel
polarization and impedance techniques. Prior to the corrosion test, the silica powder was obtained from burning the
rice husk and extended with a chemical treatment process. The size of silica powder was characterized via zeta sizer and
showed the amount of micro silica particle appear more than the nano size particle. Nano silica powder was produced
from the refluxing process of micro silica to enhance the good properties of silica particle. The corrosion inhibition
efficiency of nano silicate showed good inhibition with increased in inhibitor concentrations. Weight loss test exhibits
high inhibition as more than 80% even, immersed in the corrosive medium until 14 days. The nano silicate inhibitor
affected the anodic reaction as showed by Tafel plot analysis. Impedance results also correlated with other test as shown
by the large size of Nyquist semicircle which represents as high resistance of charge transfer. The surface morphology
of inhibited specimen showed a smooth surface after nano silicate inhibitor applied in the NaCl medium as observed
through scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX).

Matched MeSH terms: Microscopy, Electron, Scanning
Effect of annealing temperatures on TiO2 thin films prepared by spray pyrolysis deposition method

Fazli FIM, Nayan N, Ahmad MK, Mohd Napi Ml, Hamed NKA, Khalid NS

Sains Malaysiana, 2016;45:1197-1200.

Titanium dioxide (TiO2
) nanoparticles thin film has been successfully synthesized by a spray pyrolysis deposition method
by using an air compressor on a fluorine-doped tin oxide (FTO) substrate and was annealed at different temperature. TiO2
is the most common oxide as an electrode in dye sensitized solar cell (DSSC) which still has chances of improvements to
increase its efficiency as an electrode. The efficiency of a DSSC was relatively low but modifications on every part of a
DSSC were currently in research progress and an increase in adsorbed dye molecules was considered a potential. Thus,
the influences of annealing temperature on structural and morphological properties of TiO2
have been studied using
X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), respectively, while the efficiency of
the films in a solar cell was studied by a solar simulator. The FESEM result showed several degrees of porosity obtained
by varying the annealing temperature. The crystallinity of TiO2 investigated by XRD showed that the crystallinity of the
TiO2
thin films was generally unaffected by the annealing temperature. The relationship between the properties and the
efficiency of the films as an electrode was also studied

Matched MeSH terms: Microscopy, Electron, Scanning
Electrochemical corrosion behaviour of Pb-free SAC 105 and SAC 305 Solder Alloys: a comparative study

Fayeka M, Haseeb A, Fazal MA

Sains Malaysiana, 2017;46:295-302.

Sn-Ag based solder alloy seems to be a promising lead-free solder for the application on electronic assembly. The corrosion behavior of different lead free solder alloys such as Sn-3.0Ag, Sn-1.0Ag-0.5Cu and Sn-3.0Ag-0.5Cu was investigated in 3.5% NaCl solution by potentiodynamic polarization and electrochemical impedance spectroscopy. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) were used to characterize the samples after the tests. The results showed that the addition of 0.5 wt. % copper with Sn-3.0 Ag solder alloy led to a better corrosion resistance while lowering of Ag content from 3.0 to 1.0 wt. % decreased the resistance. Sn-3.0Ag-0.5Cu exhibits a better corrosion resistance in terms of increased charge transfer resistance and impedance values as well as the lowest capacitance. These characteristics signify its suitability for the application in electronic packaging.

Matched MeSH terms: Microscopy, Electron, Scanning
California bearing ratio tests of enzyme-treated sedimentary residual soil show no improvement

Tanveer Ahmed Khan, Mohd Raihan Taha, Ali Asghar Firoozi, Ali Akbar Firoozi

Sains Malaysiana, 2017;46:1269-1267.

Environmental concerns have significantly influenced the construction industry regarding the identification and use of environmentally sustainable construction materials. In this context, enzymes (organic materials) have been introduced recently for ground improvement projects such as pavements and embankments. The present experimental study was carried out in order to evaluate the compressive strength of a sedimentary residual soil treated with three different types of enzymes, as assessed through a California bearing ratio (CBR) test. Controlled untreated and treated soil samples containing four dosages (the recommended dose and two, five and 10 times the recommended dose) were prepared, sealed and cured for four months. Following the curing period, samples were soaked in water for four days before the CBR tests were administered. These tests showed no improvement in the soil is compressive strength; in other words, samples prepared even at higher dosages did not exhibit any improvement. Nuclear magnetic resonance (NMR) spectroscopy tests were carried out on three enzymes in order to study the functional groups present in them. Furthermore, X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) tests were executed for untreated and treated soil samples to determine if any chemical reaction took place between the soil and the enzymes. Neither of the tests (XRD nor FESEM) revealed any change. In fact, the XRD patterns and FESEM images for untreated and treated soil samples were indistinguishable.

Matched MeSH terms: Microscopy, Electron, Scanning
Fulltext Combination of Plant Growth Regulators, Maltose, and Partial Desiccation Treatment Enhance Somatic Embryogenesis in Selected Malaysian Rice Cultivar

Ming NGJ, Binte Mostafiz S, Johon NS, Abdullah Zulkifli NS, Wagiran A

Plants (Basel), 2019 May 30;8(6).
PMID: 31151227 DOI: 10.3390/plants8060144

The development of efficient tissue culture protocol for somatic embryo would facilitate the genetic modification breeding program. The callus induction and regeneration were studied by using different parameters i.e., auxins, cytokinins, and desiccation treatment. Scanning electron microscopy and histological analysis were performed to identify the embryogenic callus for regeneration. The callus percentage results showed that MS (Murashige and Skoog) basal medium supplemented with 3 mg/L 2, 4-D and 30g/L maltose were the optimal callus induction medium for MR220 (80%) and MR220-CL2 (95%). The morphology of the embryogenic callus was confirmed by the SEM (Scanning Electron Microscopy) (presence of extracellular matrix surface network) and later by histological analysis. Finally, MS media supplemented with 0.5 mg/L NAA (Naphthalene Acetic Acid), 2 mg/L kin, and 1 mg/L BAP were selected as the optimum regeneration media treatment while callus desiccated for 48 h was proved to produce more plantlets in MR220 (60%) and MR220-CL2 (73.33%) compared to control treatment (without desiccation). The protocol presented here showed the necessity for the inclusion of partial desiccation as an important step in the tissue culture protocol of Malaysian indica rice genotypes in order to enhance their regeneration potential.

Matched MeSH terms: Microscopy, Electron, Scanning
Effect of radio frequency power on a-cnx film properties and its performance as humidity sensors

Rozidawati Awang, Noorain Purhanudin, Nur Sakinah Salman

Sains Malaysiana, 2018;47:2863-2867.

A series of amorphous carbon nitride (a-CNx) thin films were deposited on silicon (111) substrates using a home-built
radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) system. The a-CNx thin films were deposited
from a mixture of a fixed flow-rate of ethane (C2
H6
, 20 sccm) and nitrogen (N2
, 47 sccm) gases with varying RF power. A
higher ratio of C to H (C to H ratio is 1:3) atoms in C2
H6
as compared to the ratio in methane (CH4
) gas (C to H ratio is
1:4) is expected to produce an interesting effect to the film properties as humidity sensor. The characterization techniques
used to determine the morphology and chemical bonding of the thin films are field emission scanning electron microscopy
(FESEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The variation of morphology and the existence
of nitrile band in these samples are correlated with the electrical properties of a-CNx thin films. Using humidity sensing
system, the sensing performance of the samples was examined. It was found that the response of sensors towards the
percentage of relative humidity (% RH) change is good resistive responses and good repeatability. The sensitivity of the
prepared a-CNx thin films is significantly higher (up to 79%) as compared to previous studies using CH4
or acetylene as
precursor gas. Based on these results, the properties and the sensitivity of the a-CNx thin films towards humidity can be
tailored by using an appropriate precursor gases and deposition parameters.

Matched MeSH terms: Microscopy, Electron, Scanning
Preparation and characterization of impregnated magnetic particles on Oil Palm Frond Activated Carbon for metal ions removal

Muzakkir Mohammad Zainol, Nor Aishah Saidina Amin, Mohd Asmadi

Sains Malaysiana, 2017;46:773-782.

The magnetic adsorbents i.e. oil palm frond-magnetic particles (OPF-MP) and oil palm frond activated carbon-magnetic particles (OPFAC-MP) have been prepared by impregnation of iron oxide via co-precipitation method. The magnetic adsorbents and their parent materials were characterized using Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), Brunauer Emmett Teller (BET), Barrett, Joyner & Halenda (BJH) and t-plot method, x-ray diffraction (XRD) and also using vibrating sample magnetometry (VSM) to study their properties and surface chemistry. The activated carbon magnetic adsorbent confers high surface area of 700 m2/g with amorphous structure and magnetic properties of 2.76 emu/g. The OPF-MP and OPFAC-MP were then applied in adsorption study for ions removal of Pb(II), Zn(II) and Cu(II). OPFAC-MP has shown high removal efficiency of 100 % with adsorption capacity up to 15 mg/g of Pb(II), Zn(II) and Cu(II) ions compared to OPF-MP. In addition, the magnetic adsorbents were also compared with their parent materials to observe the effect of magnetic particles. Accordingly, the impregnation of magnetic particles enhances the metal ions adsorption comparing to their parent materials.

Matched MeSH terms: Microscopy, Electron, Scanning

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