Displaying publications 21 - 40 of 148 in total

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  1. Azizul Isha, Nor Azah Yusof, Musa Ahmad, Dedy Suhendra, Wan Md. Zin Wan Yunus, Zulkarnain Zainal
    MyJurnal
    An artificial neural network (ANN) was applied for the determination of V(V) based on immobilized fatty hydroxamic acid (FHA) in poly(methyl methacrylate) (PMMA). Spectra obtained from the V(V)-FHA complex at single wavelengths was used as the input data for the ANN. The V(V)-FHA complex shows a limited linear dynamic range of V(V) concentration of 10 - 100 mg/ L. After training with ANN, the linear dynamic range was extended with low calibration error. A three layer feed forward neural network using backpropagation (BP) algorithm was employed in this study. The input layer consisted of single neurons, 30 neurons in hidden a layer and one output neuron was found appropriate for the multivariate calibration used. The network were trained up to 10000 epochs with 0.003 % learning rate. This reagent also provided a good analytical pedormance with reproducibility characters of the method yielding relative standard deviation (RSD) of 9.29% and 7.09% for V(V) at concentrations of 50 mg/ L and 200 mg/ L, respectively. The limit of detection of the method was 8.4 mg/ L.
  2. Wardatun Nadrah Mohd Amin, Zainal Abidin Talib, Zulkarnain Zainal, Hong Ngee, Lim, Sook Keng, Chang
    MyJurnal
    Quantum dots-sensitized solar cell (QDSSC) is one of the third generation solar cell that is
    the most promising low cost, easy to manufacture and highly efficient solar cell. Compared to Dyesensitized
    solar cell (DSSC), quantum dots (QDs) of QDSSC has a narrow bandgap and possess
    excellent properties such as tunable band gaps, strong light absorption and high multiple electron
    generation. Titanium dioxide or titania (TiO2) is an oxides semiconductor material that is frequently
    used as a photoanode in this photovoltaic system due to high stability under visible light illumination.
    TiO2 is also known as a good photocatalyst and an excellent choice in environmental purification. The
    efficiencies of electron injection and light harvesting in QDSSC are affected by the nature, size
    morphology, and quantity of this nanomaterial. In this review, the concept and principles of the
    QDSSCs are reviewed. The preparation and fabrication method ofTiO2 electrode in QDSSC are also
    discussed. It is worthwhile to know the architecture of TiO2 in order to enhance the efficiency of
    QDSSC.
  3. Nurul Asma Samsudin, Zulkarnain Zainal, Lim, Hong-Ngee, Yusran Sulaiman, Chang, Sook-Keng
    MyJurnal
    Titania nanotube is gaining tremendous interest for its unique features including high
    surface area, ion-exchange ability, photocatalytic potential and prominent electrical properties. Many
    attempts were made to manipulate the unique properties of titania nanotubes for supercapacitor
    application. In this review a comprehensive list of literatures on fabrication of titania nanotubes via
    anodisation method in fluoride-based electrolytes and its application as supercapacitor are discussed.
    This review shows that the nanotube morphology can be optimized by varying the anodisation
    parameter such as electrolyte concentration, pH, voltage, and bath temperature. The review also
    includes studies on the application of titania nanotubes as supercapacitor on improving the specific
    capacitance value by doping with metal oxides and conducting polymers.
  4. 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.
  5. Khaw CC, Tan KB, Zulkarnain Zainal, Lee CK
    Bi3Zn2Ta3O14, ‘P’, was crystallised in a cubic unit cell with lattice parameter of a=10.5437 (9) Å. The material had permittivity, ε’, of around 58 and dielectric loss, tan δ, of 2.3 × 10-3 at 30oC, 1 MHz; temperature coefficient of capacitance (TCC) of -156 ppm/oC in the range of 30oC to 300oC at 1 MHz. Chemical doping was carried out at either A (Bi1.5Zn0.5-xMx)(Zn0.5Ta1.5)O7, or B site (Bi1.5Zn0.5)(Zn0.5-xMxTa1.5)O7 in search of better performance materials. Various divalent cations such as Cd2+, Ca2+, Mg2+, Ni2+, Pb2+, and Cu2+ were used as dopants. Solid solutions formed were: Bi3Zn2-xCdxTa3O14 (0≤x≤0.5), Bi3Zn2-xMgxTa3O14(0≤x≤0.2), Bi3Zn2-xNixTa3O14 (0≤x≤0.4), Bi3Zn2-xPbxTa3O14 (0≤x≤0.3), Bi3Zn2-xCaxTa3O14 (0≤x≤0.3) and Bi3Zn2-xCuxTa3O14 (0≤x≤0.1). Electrical properties of the materials were investigated using impedance spectroscopy. Conductivities of the solid solutions were higher than that of the parent material Bi3Zn2Ta3O14. These doped materials exhibited similar behaviour as Bi3Zn2Ta3O14, showing a high degree of dispersion of permittivity at low frequencies (<1 kHz) and at temperatures above 500oC. Between 100 kHz and 1000 kHz, non-frequency dependence was observed in the range of 100 – 300oC. An increase in dielectric loss below 10 kHz was observed. Dielectric loss decreased with frequencies when temperature was above 500oC. Dielectric loss of all divalent cation doped materials was higher than that of the parent material; maximum permittivity value of 68 was recorded at x = 0.3 in Bi3Zn2-xCaxTa3O14. TCC obtained in this study had negative values; no obvious correlation between TCC and composition of the doped materials can be deduced.
  6. Nima Ghamarian, Azmah Hanim, M.A., Nahavandi, M., Zulkarnain Zainal, Lim, Hong Ngee
    MyJurnal
    In the recent years, electronic packaging provides significant research and development challenges
    across multiple disciplines such as performance, materials, reliability, thermals and interconnections.
    New technologies and techniques frequently adopted can be implemented in soldering alloys of
    semiconductor sectors in terms of optimisation. Wetting contact angle or wettability of solder alloys
    is one of the important factors which has got the attention of scholars. Hence in this study, due to the
    remarkable similarity over classical solder alloys (Pb-Sn), Bi-Ag solder was investigated. Data were
    collected through the effects of aging time variation and different weight percentages of Ag in solder
    alloys. The contact angle of the alloys with Cu plate was measured by optical microscopy. Artificial
    neural networks (ANNs) were applied on the measured datasets to develop a numerical model for further
    simulation. Results of the experiments and simulations showed that the coefficient of determination (R2
    )
    is around 0.97, which signifies that the ANN set up is appropriate for the evaluation.
  7. Taer E, Yanti N, Padang E, Apriwandi A, Zulkarnain Z, Haryanti NH, et al.
    J Sci Food Agric, 2023 Dec;103(15):7411-7423.
    PMID: 37431642 DOI: 10.1002/jsfa.12846
    BACKGROUND: Porous carbon electrode (PCE) is identified as a highly suitable electrode material for commercial application due to its production process, which is characterized by simplicity, cost-effectiveness and environmental friendliness. PCE was synthesized using torch ginger (Etlingera elatior (Jack) R.M. Smith) leaves as the base material. The leaves were treated with different concentrations of ZnCl2 , resulting in a supercapacitor cell electrode with unique honeycomb-like three-dimensional (3D) morphological pore structure. This PCE comprises nanofibers from lignin content and volatile compounds from aromatic biomass waste.

    RESULTS: From the characterization of physical properties, PCE-0.3 had an impressive amorphous porosity, wettability and 3D honeycomb-like structural morphology with a pore framework consisting of micropores and mesopores. According to the structural advantages of 3D hierarchical pores such as interconnected honeycombs, PCE-0.3 as supercapacitor electrode had a high specific capacitance of up to 285.89 F g-1 at 1 A. Furthermore, the supercapacitor exhibited high energy and power density of 21.54 Wh kg-1 and 161.13 W kg-1 , respectively, with a low internal resistance of 0.059 Ω.

    CONCLUSION: The results indicated that 3D porous carbon materials such as interconnected honeycombs derived from the aromatic biomass of torch ginger leaves have significant potential for the development of sustainable energy storage devices. © 2023 Society of Chemical Industry.

  8. Swamy M, Suhaili D, Sirajudeen KN, Mustapha Z, Govindasamy C
    PMID: 25395704
    BACKGROUND: Increased nitric oxide (NO), neuronal inflammation and apoptosis have been proposed to be involved in excitotoxicity plays a part in many neurodegenerative diseases. To understand the neuro-protective effects of propolis, activities of Nitric oxide synthase (NOS) and caspase-3 along with NO and tumor necrosis factor-α (TNF-α) levels were studied in cerebral cortex (CC), cerebellum (CB) and brain stem (BS) in rats supplemented with propolis prior to excitotoxic injury with kainic acid (KA).

    MATERIALS AND METHODS: Male Sprague-Dawley rats were divided into four groups (n=6 rats per group) as Control, KA, Propolis and KA+Propolis. The control group and KA group have received vehicle and saline. Propolis group and propolis + KA group were orally administered with propolis (150 mg/kg body weight), five times every 12 hours. KA group and propolis +KA group were injected subcutaneously with kainic acid (15 mg/kg body weight) and were sacrificed after 2 hrs. CC, CB and BS were separated, homogenized and used for estimation of NOS, caspase-3, NO and TNF-α by commercial kits. Results were analyzed by one way ANOVA, reported as mean + SD (n=6 rats), and p<0.05 was considered statistically significant.

    RESULTS: The concentration of NO, TNF-α, NOS and caspase-3 activity were increased significantly (p<0.001) in all the three brain regions tested in KA group compared to the control. Propolis supplementation significantly (p<0.001) prevented the increase in NOS, NO, TNF-α and caspase-3 due to KA.

    CONCLUSION: Results of this study clearly demonstrated that the propolis supplementation attenuated the NOS, caspase-3 activities, NO, and TNF-α concentration and in KA mediated excitotoxicity. Hence propolis can be a possible potential protective agent against excitotoxicity and neurodegenerative disorders.

  9. Barahuie F, Hussein MZ, Fakurazi S, Zainal Z
    Int J Mol Sci, 2014;15(5):7750-86.
    PMID: 24802876 DOI: 10.3390/ijms15057750
    Layered hydroxides (LHs) have recently fascinated researchers due to their wide application in various fields. These inorganic nanoparticles, with excellent features as nanocarriers in drug delivery systems, have the potential to play an important role in healthcare. Owing to their outstanding ion-exchange capacity, many organic pharmaceutical drugs have been intercalated into the interlayer galleries of LHs and, consequently, novel nanodrugs or smart drugs may revolutionize in the treatment of diseases. Layered hydroxides, as green nanoreservoirs with sustained drug release and cell targeting properties hold great promise of improving health and prolonging life.
  10. Hamid MS, Jaafar Z, Mohd Ali AS
    PLoS One, 2014;9(4):e95158.
    PMID: 24733140 DOI: 10.1371/journal.pone.0095158
    In Malaysia, futsal is a popular sport played by individuals across all ages and genders. Despite its popularity, information on futsal related injury in Malaysia is not available. The purpose of this study is to examine the injury incidence and injury patterns among amateur men and women futsal players in Malaysia.
  11. Nik Yusoff NS, Mustapha Z, Govindasamy C, Sirajudeen KN
    Oxid Med Cell Longev, 2013;2013:927214.
    PMID: 23766863 DOI: 10.1155/2013/927214
    Hypertension is a risk factor for several cardiovascular diseases and oxidative stress suggested to be involved in the pathophysiology. Antihypertensive drug Clonidine action in ameliorating oxidative stress was not well studied. Therefore, this study investigate the effect of Clonidine on oxidative stress markers and nitric oxide (NO) in SHR and nitric oxide synthase inhibitor, N-nitro-L-arginine methyl ester (L-NAME) administered SHR. Male rats were divided into four groups [SHR, SHR+Clonidine (SHR-C), SHR+L-NAME, SHR+Clonidine+L-NAME(SHRC+L-NAME)]. Rats (SHRC) were administered with Clonidine (0.5 mg kg(-1) day(-1)) from 4 weeks to 28 weeks in drinking water and L-NAME (25 mg kg(-1) day(-1)) from 16 weeks to 28 weeks to SHRC+L-NAME. Systolic blood pressure (SBP) was measured. At the end of 28 weeks, all rats were sacrificed and in their heart homogenate, oxidative stress parameters and NO was assessed. Clonidine treatment significantly enhanced the total antioxidant status (TAS) (P < 0.001) and reduced the thibarbituric acid reactive substances (TBARS) (P < 0.001) and protein carbonyl content (PCO) (P < 0.05). These data suggest that oxidative stress is involved in the hypertensive organ damage and Clonidine not only lowers the SBP but also ameliorated the oxidative stress in the heart of SHR and SHR+L-NAME.
  12. Abdollahi Y, Abdullah AH, Zainal Z, Yusof NA
    Int J Mol Sci, 2012;13(1):302-15.
    PMID: 22312253 DOI: 10.3390/ijms13010302
    Photocatalytic degradation of p-cresol was carried out using ZnO under UV irradiation. The amount of photocatalyst, concentration of p-cresol and pH were studied as variables. The residual concentration and mineralization of p-cresol was monitored using a UV-visible spectrophotometer and total organic carbon (TOC) analyzer, respectively. The intermediates were detected by ultra high pressure liquid chromatography (UPLC). The highest photodegradation of p-cresol was observed at 2.5 g/L of ZnO and 100 ppm of p-cresol. P-cresol photocatalytic degradation was favorable in the pH range of 6-9. The detected intermediates were 4-hydroxy-benzaldehyde and 4-methyl-1,2-benzodiol. TOC studies show that 93% of total organic carbon was removed from solution during irradiation time. Reusability shows no significant reduction in photocatalytic performance in photodegrading p-cresol.
  13. Hussein MZ, Rahman NS, Sarijo SH, Zainal Z
    Int J Mol Sci, 2012;13(6):7328-42.
    PMID: 22837696 DOI: 10.3390/ijms13067328
    Herbicides, namely 4-(2,4-dichlorophenoxy) butyrate (DPBA) and 2-(3-chlorophenoxy) propionate (CPPA), were intercalated simultaneously into the interlayers of zinc layered hydroxide (ZLH) by direct reaction of zinc oxide with both anions under aqueous environment to form a new nanohybrid containing both herbicides labeled as ZCDX. Successful intercalation of both anions simultaneously into the interlayer gallery space of ZLH was studied by PXRD, with basal spacing of 28.7 Å and supported by FTIR, TGA/DTG and UV-visible studies. Simultaneous release of both CPPA and DPBA anions into the release media was found to be governed by a pseudo second-order equation. The loading and percentage release of the DPBA is higher than the CPPA anion, which indicates that the DPBA anion was preferentially intercalated into and released from the ZLH interlayer galleries. This work shows that layered single metal hydroxide, particularly ZLH, is a suitable host for the controlled release formulation of two herbicides simultaneously.
  14. Hussein MZ, Al Ali SH, Zainal Z, Hakim MN
    Int J Nanomedicine, 2011;6:1373-83.
    PMID: 21796241 DOI: 10.2147/IJN.S21567
    An ellagic acid (EA)-zinc layered hydroxide (ZLH) nanohybrid (EAN) was synthesized under a nonaqueous environment using EA and zinc oxide (ZnO) as the precursors. Powder X-ray diffraction showed that the basal spacing of the nanohybrid was 10.4 Å, resulting in the spatial orientation of EA molecules between the interlayers of 22.5° from z-axis with two negative charges at 8,8' position of the molecules pointed toward the ZLH interlayers. FTIR study showed that the intercalated EA spectral feature is generally similar to that of EA, but with bands slightly shifted. This indicates that some chemical bonding of EA presence between the nanohybrid interlayers was slightly changed, due to the formation of host-guest interaction. The nanohybrid is of mesopores type with 58.8% drug loading and enhanced thermal stability. The release of the drug active, EA from the nanohybrid was found to be sustained and therefore has good potential to be used as a drug controlled-release formulation. In vitro bioassay study showed that the EAN has a mild effect on the hepatocytes cells, similar to its counterpart, free EA.
  15. Ebrahimiasl S, Yunus WM, Kassim A, Zainal Z
    Sensors (Basel), 2011;11(10):9207-16.
    PMID: 22163690 DOI: 10.3390/s111009207
    Nanocrystalline SnO(x) (x = 1-2) thin films were prepared on glass substrates by a simple chemical bath deposition method. Triethanolamine was used as complexing agent to decrease time and temperature of deposition and shift the pH of the solution to the noncorrosive region. The films were characterized for composition, surface morphology, structure and optical properties. X-ray diffraction analysis confirms that SnO(x) thin films consist of a polycrystalline structure with an average grain size of 36 nm. Atomic force microscopy studies show a uniform grain distribution without pinholes. The elemental composition was evaluated by energy dispersive X-ray spectroscopy. The average O/Sn atomic percentage ratio is 1.72. Band gap energy and optical transition were determined from optical absorbance data. The film was found to exhibit direct and indirect transitions in the visible spectrum with band gap values of about 3.9 and 3.7 eV, respectively. The optical transmittance in the visible region is 82%. The SnO(x) nanocrystals exhibit an ultraviolet emission band centered at 392 nm in the vicinity of the band edge, which is attributed to the well-known exciton transition in SnO(x). Photosensitivity was detected in the positive region under illumination with white light.
  16. Sarijo SH, Hussein MZ, Yahaya AH, Zainal Z
    J Hazard Mater, 2010 Oct 15;182(1-3):563-9.
    PMID: 20633986 DOI: 10.1016/j.jhazmat.2010.06.070
    The release of chlorophenoxyherbicides agrochemicals, namely 2-chloro- (2CPA), 4-chloro and 2,4,5-trichloro (TCPA) phenoxyacetates from their nanohybrids into various aqueous solutions; carbonate, sulfate and chloride was found to be controlled by pseudo-second order rate expression. The percentage saturated released was found to be anionic-dependent, in the order of carbonate>sulfate>chloride for the release media and 2CPA>4CPA>TCPA for the anionic guests. This study demonstrates that the release of the phenoxyherbicides agrochemicals from the nanohybrid compounds can be tuned by choosing the right combination of exchangeable anions both the incoming and the outgoing anions.
  17. Gaya UI, Abdullah AH, Zainal Z, Hussein MZ
    J Hazard Mater, 2009 Aug 30;168(1):57-63.
    PMID: 19268454 DOI: 10.1016/j.jhazmat.2009.01.130
    The photocatalytically driven removal of eco-persistent 4-chlorophenol from water using ZnO is reported here. Kinetic dependence of transformation rate on operating variables such as initial 4-chlorophenol concentration and photocatalyst doses was investigated. A complete degradation of 4-chlorophenol at 50 mg L(-1) levels was realised in 3h. Analytical profiles on 4-chlorophenol transformation were consistent with the best-line fit of the pseudo zero-order kinetics. The addition of small amounts of inorganic anions as SO(4)(2-), HPO(4)(-), S(2)O(8)(2-) and Cl(-) revealed two anion types: active site blockers and rate enhancers. Fortunately, Cl(-) and SO(4)(2-) commonly encountered in contaminated waters enhanced the rate of 4-chlorophenol degradation. The reaction intermediates and route to 4-chlorophenol mineralisation were elucidated by combined RP-HPLC and GC-MS methods. In addition to previously reported pathway products of 4-chlorophenol photo-oxidation catechol was detected. A radical mechanism involving o-hydroxylation is proposed to account for the formation of catechol.
  18. Hussein MZ, Kuang D, Zainal Z, Teck TK
    J Colloid Interface Sci, 2001 Mar 1;235(1):93-100.
    PMID: 11237447
    Kaolin-carbon adsorbents were prepared with and without sulfuric acid pretreatment followed by activation-carbonization at 500 degrees C. The total surface area of the resulting kaolin-carbon adsorbents was found to be decreased with the increase in kaolin loading. Sulfuric acid pretreatment of the precursor prior to the carbonization-activation processes resulted in the enhancement of total surface area but reduced the micropore surface area of the resulting adsorbents. At the same time, this improved carotene adsorption capacity from red palm oil. However, recovery of carotene from the carotene-adsorbed adsorbent is only improved when the acid pretreatment of the precursor was done at a high loading percentage of activated carbon. Similarly, the peroxide value (PV) increased. A maximum removal of carotene from red palm oil was obtained at 20% kaolin loading for both adsorbents prepared with and without sulfuric acid pretreatment with about 45 and 65% carotene removal, respectively, from a 30-ppm solution. This indicates that pretreatment with sulfuric acid, prior to the activation-carbonization process, increased the carotene uptake by the resulting adsorbent. However, a further increase in the kaolin loading resulted in the decrease of carotene removal. About 3-4% of carotene adsorbed can be recovered from both types of adsorbents under optimum condition, in which the percentage recovered decreased with the increase in kaolin loading. On the other hand, the PV increased with kaolin loading at around 54-64 mEq/kg for both types of adsorbents. It was also found that carotene uptake by the adsorbents is high if the adsorbent contains a high percentage of activated carbon. Similarly, carotene recovery is high and less oxidation can be observed, as indicated by the lower PV value. Copyright 2001 Academic Press.
  19. bin Hussein MZ, Zainal Z, Yahaya AH, Foo DW
    J Control Release, 2002 Aug 21;82(2-3):417-27.
    PMID: 12175754
    Formation of the so-called organic-inorganic nanohybrid material was exploited for the preparation of a controlled release formulation. The inorganic Zn-Al-layered double hydroxide (LDH) was used as a matrix, hosting an active agent or a guest, alpha-naphthaleneacetate (NAA), a plant growth regulator by self-assembly technique. The reverse process, i.e., the deintercalation or release of the guest, NAA was found to be rapid initially, followed by a more sustained release thereafter and this behavior was dependent on the pH of the release medium, the aqueous solution. The mechanism of release has been interpreted on the basis of the ion-exchange process between the NAA anion intercalated in the lamella host and nitrate or hydroxyl anions in the aqueous solution.
  20. Ellis-Suriani Z, Norsa'adah B, Othman A, Siti-Azrin AH
    Tob Induc Dis, 2021;19:27.
    PMID: 33867904 DOI: 10.18332/tid/133638
    INTRODUCTION: Secondhand smoke (SHS) exposure is linked to a series of serious health problems. Children may be particularly vulnerable to the effects of SHS exposure at home. This study aimed to determine the association between SHS exposure at home and cognitive performance in school children.

    METHODS: A multistage sampling was performed across rural primary schools in Kuala Krai, Kelantan, Malaysia. Data were collected using self-administered questionnaires and the children aged 10-11 years (n=312) were subjected to cognitive tests including digit span, letter-number sequencing, coding, and symbol search. Cognitive performance was tested using subscales derived from the Wechsler Intelligence Scale for Children.

    RESULTS: The prevalence of SHS exposure at home was 55.8%, where 11.9% of children lived with one smoker, while 43.9% of children lived with ≥2 smokers. There was a significant difference in the mean score of the combined cognitive tests between SHS-exposed and non-exposed children after adjustment for sex, parental educational level, family income and academic performance [Pillai's Trace=0.084, F statistic (df)=6.803 (4302), p<0.001].

    CONCLUSIONS: More than half of the primary school children in rural Kuala Krai were exposed to SHS from at least one smoker at home. There was a significant association between SHS exposure at home and cognitive performance.

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