Effect of Unsaturation on the Stability of C₁₈ Polyunsaturated Fatty Acids Vesicles Suspension in Aqueous Solution

Teo, Yin Yin,Misran, Misni,Low, Kah Hin,Zain, Sharifuddin Md. Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.1

Degree of unsaturation in fatty acid molecules plays an important role in the formation of vesicles. Vesicle formation from C18 fatty acids with different amount of double bonds such as oleic acid, linoleic acid and linolenic acid with the incorporation of 1,2-dipalmitoyl-sn-glycerol-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DPPE-PEG2000) have been examined by TEM. Critical vesicular concentrations (CVC) of the vesicle suspension are determined by turbidity and surface tension methods. The CVC of fatty acids increases when the amount of unsaturation in the alkyl chain increases. On the other hand, stability of vesicle suspension has been examined by using particle size and zeta potential at $30^{\circ}C$. There was a dramatic decrease in particle size measurement from mono-unsaturation to tri-unsaturation which could be due to the effect of fluidity in the membrane bilayer caused by different degree of unsaturation. The values of zeta potential for vesicles that were formed without the incorporation of DPPE-PEG2000 were in the range of -70 mV to -100 mV. It has been observed that the incorporation of DPPEPEG2000 to the vesicle reduces the magnitude of zeta potential. However, this phenomenon does not obviously seen in fatty acid vesicles formed by linoleate-linoleic acid and linolenate-linolenic acid. We therefore conclude that the addition of DPPE-PEG2000 does not effectively improve the stability of the linoleate-linoleic acid and linolenatelinolenic acid vesicle at pH 9.0 after the evaluation of their particle size and zeta potential over a period of 30 days. Although the vesicles formed were not stable for more than 10 days, they have displayed the potential in encapsulating the active ingredients such as vitamin E and calcein. The results show that the loading efficiencies of vitamin E are of encouraging value.

Photocatalytic reduction of Cr(VI) by PVA-alginate encapsulated gFe2O3 magnetic beads using different types of illumination lamp and light

Ani Idris,Effaliza Misran,Noordin Mohd Yusof 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.6

In this study the toxic Cr(VI) which is a common pollutant to the environment is removed from the aqueous solution using the one step photocatalytic reduction to Cr(III) using PVA-alginate encapsulated gFe2O3 magnetic beads. The photocatalytic reduction of Cr(VI) by PVA-alginate encapsulated gFe2O3 magnetic beads was examined under sunlight and other 4 types of lamp: xenon lamp, black light bulb (BLB) lamp, light emitting diode (LED) lamp and fluorescent lamp. The experiments were performed at pH 1, initial Cr(VI) = 50 mg/L and the photocatalyst dosage of maghemite nanoparticles was kept at 8% (v/v). Removal of Cr(VI) was best under sunlight; 100% removal in 30 min, followed by xenon lamp; 100% removal in 100 min, BLB lamp; 70% removal in 100 min. LED and fluorescent lamp have about the same removal rate; 50% removal in 100 min. The Cr(VI) reduction using PVA-alginate magnetic beads fitted the Langmuir–Hinshelwood (L–H) kinetics model with a correlation coefficient (R2) of 0.972. The PVAalginate magnetic beads were capable of treating industrial chromium waste containing 300 mg/L Cr(VI) within 2 h under sunlight.

A Spectrally Efficient Macrodiversity Handover Technique for Interference-Limited IEEE 802.16j Multihop Wireless Relay Networks

Jamil Sultan,Norbahiah Misran,Mahamod Ismail,Mohammad Tariqul Islam 한국전자통신연구원 2011 ETRI Journal Vol.33 No.4

In this paper, we propose an efficient macrodiversity handover (MDHO) technique for time-division-based interference-limited IEEE 802.16j multihop wireless relay networks. In the proposed MDHO, when the diversity set members of the mobile station (MS) are a base station (BS) and relay station (RS), the MS receives the signal transmitted by the BS in the first phase. During the second phase, it also receives the simultaneous transmissions of the BS and RS. Furthermore, when the diversity set members are two RSs or two BSs, the MS receives only the simultaneous transmissions of the diversity set members. The superiority of the proposed MDHO is validated using analytical and simulation results. The performance analysis metrics are the average downlink (DL) carrier to interference and noise ratio (CINR), the average DL spectral efficiency, and the average service outage probability. Evaluation results show that the proposed MDHO significantly outperforms the conventional MDHO. The CINR gain achieved using the proposed MDHO is 4.71 dB compared to the conventional MDHO.

Effect of Unsaturation on the Stability of C_18 Polyunsaturated Fatty Acids Vesicles Suspension in Aqueous Solution

Yin Yin Teo,Misni Misran,Kah Hin Low,Sharifuddin Md. Zain 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.1

Degree of unsaturation in fatty acid molecules plays an important role in the formation of vesicles. Vesicle formation from C18 fatty acids with different amount of double bonds such as oleic acid, linoleic acid and linolenic acid with the incorporation of 1,2-dipalmitoyl-sn-glycerol-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000](DPPE-PEG2000) have been examined by TEM. Critical vesicular concentrations (CVC) of the vesicle suspension are determined by turbidity and surface tension methods. The CVC of fatty acids increases when the amount of unsaturation in the alkyl chain increases. On the other hand, stability of vesicle suspension has been examined by using particle size and zeta potential at 30 ^oC. There was a dramatic decrease in particle size measurement from mono-unsaturation to tri-unsaturation which could be due to the effect of fluidity in the membrane bilayer caused by different degree of unsaturation. The values of zeta potential for vesicles that were formed without the incorporation of DPPE-PEG2000 were in the range of ‒70 mV to ‒100 mV. It has been observed that the incorporation of DPPEPEG2000to the vesicle reduces the magnitude of zeta potential. However, this phenomenon does not obviously seen in fatty acid vesicles formed by linoleate-linoleic acid and linolenate-linolenic acid. We therefore conclude that the addition of DPPE-PEG2000 does not effectively improve the stability of the linoleate-linoleic acid and linolenatelinolenic acid vesicle at pH 9.0 after the evaluation of their particle size and zeta potential over a period of 30 days. Although the vesicles formed were not stable for more than 10 days, they have displayed the potential in encapsulating the active ingredients such as vitamin E and calcein. The results show that the loading efficiencies of vitamin E are of encouraging value.

Arabic Gum Grafted PEGDMA Hydrogels: Synthesis, Physico-Chemical Characterization and In-vitro Release of Hydrophobic Drug

Sani Mamman Ibrahim,Teo Yin Yin,Misni Misran 한국고분자학회 2020 Macromolecular Research Vol.28 No.13

Hydrogel development using natural and synthetic polymers for biomedical applications have shown promising properties for drug delivery due to virtuous stimuli response and improvement in mechanical strength. Biomaterial hydrogel was synthesized using combination of arabic gum (AG), a natural polymer and polyethylene glycol dimethacrylate (PEGDMA), a synthetic polymer. The synthesis process follows chemical cross linking by free radical polymerization. Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and differential scanning calorimetry (DSC) were used to characterize the hydrogels. Product yield, gel content and gelation time depends solely on the variable reacting concentrations and the mechanical properties of hydrogel depends on its compositions. Swelling studies reveal high swelling ratio in buffer solution pH 1.2 compare to buffer solution pH 7.4, and deionized water at pH 6.7. Swelling ratio raises with increase in PEGDMA concentration, but the presences of salt/ions solutions decreases the swelling ratio significantly and it depends on the charge of the ions. The kinetics of the swelling follows a second order non-linear rate equation. The rate of degradation revealed significant degradation in acidic medium and insignificant degradation was observed in basic medium. The encapsulation efficiency of quercetin introduced directly in the hydrogels during synthesis was found in the range of 85-94%. The release profile indicates the dependence of arabic gum grafted PEGDMA hydrogels on pH and compositions. The characteristic properties exhibited by the formulated hydrogels suggest the suitability of them to be applied as drug carriers.

Synthesis of magnetic alginate beads based on maghemite nanoparticles for Pb(II) removal in aqueous solution

Ani Idris,Nur Suriani Mohd Ismail,Nursia Hassan,Effaliza Misran,Audrey-Flore Ngomsik 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.5

Magnetic alginate beads were successfully synthesized by incorporating ferrofluids based on maghemite nanoparticles (g-Fe2O3) and sodium alginate. The as-obtained dried sample characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed that the size of uncoated and citrate coated g-Fe2O3 to be 15 nm and 9 nm respectively. Fourier transform infrared (FTIR) was performed so as to ensure successful coating process. The specific saturation magnetization (ss) value of coated particles was found to be lower than the uncoated particles. Zero coercivity of the magnetization curve indicated that the particles were superparamagnetic in nature. By using a ratio 1:10 of ferrofluids and alginate solution respectively, magnetic beads were prepared and the ability of magnetic beads to remove Pb(II) ion from aqueous solutions in batch media was investigated. Various physico-chemical parameters such as pH,initial metal ion concentration, and equilibrium contact time were also studied. The results revealed that 95.2% of the Pb(II) was removed within 2 h at pH 7. The equilibrium amount of Pb(II) adsorbed onto the magnetic beads approached a constant value with increasing concentrations suggesting that the uptake of Pb(II) followed a Langmuir-type adsorption equation with qmax of 50 mg/g. Moreover, the presence of the magnetic particles in the beads allowed easy isolation of the beads from the aqueous solutions after the sorption process. In order to determine the reusability potential of the adsorbent, the isolated beads were used as a regenerated sorbent in repeated sorption–desorption cycles. Results revealed that the magnetic beads produced can be potentially used for the treatment of waste water contaminated with heavy metals and regenerated at least five times before losing their activity.

Polyvinyl alcohol–alginate ferrophoto gels for mercury(II) removal

Azura Hanis A. Rahman,Chee Loong Teo,Ani Idris,Effaliza Misran,Siti Asma’ Nikmat Leong 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.33 No.-

Maghemite (g-Fe2O3) nanoparticles were embedded in polyvinyl alcohol (PVA) and alginate matrix toproduce beads that could be easily recovered with external magnetic field after treating mercury, Hg(II)in aqueous solution. 96% of Hg(II) was removed in 4 h under sunlight, at pH 11 and 16% (v/v) ofphotocatalyst dosage. FESEM results revealed that the beads possessed significant superporositystructure that greatly supported mass transfer of Hg(II) inside the beads. The removal of Hg(II) fitted wellwith Langmuir–Hinshelwood (L–H) model exhibiting R2 (correlation coefficient) value of 0.9771. Thus,this study proved that it was feasible to treat Hg(II) solution with g-Fe2O3–PVA–alginate beads.

Simultaneous Spectrophotometric Determination of Copper, Nickel, and Zinc Using 1-(2-Thiazolylazo)-2-Naphthol in the Presence of Triton X-100 Using Chemometric Methods

Low, Kah Hin,Zain, Sharifuddin Md.,Abas, Mhd. Radzi,Misran, Misni,Mohd, Mustafa Ali Korean Chemical Society 2009 대한화학회지 Vol.53 No.6

Triton X-100이 함유된 상태에서 정색시약인 1-(2-thiazolylazo)-2-naphthol이 첨가된 물에서 구리 (II), 니켈(II)과 아연(II)의 동시 분광광도법적 정량을 위한 다변량 모델들이 개발되었다. 분광학적 간섭의 단점을 극복하기 위해서, 주성분회귀분석법(PCR)과 부분최소자승법(PLS) 다변량 분석법적 접근이 적용되었다. 다양한 시험 세트를 사용하여 본 방법의 수행이 입증되었고 그 결과들이 비교되었다. 일반적으로 PLS와 PCR 모델들 사이에 분석적 수행에서의 심각한 차이가 없었다. $Cu^{2+}$, $Ni^{2+}$ and $Zn^{2+}$ 의 세 성분들을 사용한 예측의 제곱근 평균 제곱 오차(RMSEP)들은 각각 0.018, 0.010, 0.011 ppm이었다. 또한 감도, 분석감도, 검출한계(LOD)와 같은 가치들의 측면들이 평가되었다. 본 논문에서 제안하는 과정이 화합물 혼합용액과 수돗물 속의 $Cu^{2+}$, $Ni^{2+}$ and $Zn^{2+}$의 동시 검출에 적용되었을 때에 높은 신뢰도가 성취되었다. Multivariate models were developed for the simultaneous spectrophotometric determination of copper (II), nickel (II) and zinc (II) in water with 1-(2-thiazolylazo)-2-naphthol as chromogenic reagent in the presence of Triton X-100. To overcome the drawback of spectral interferences, principal component regression (PCR) and partial least square (PLS) multivariate calibration approaches were applied. Performances were validated with several test sets, and their results were then compared. In general, no significant difference in analytical performance between PLS and PCR models. The root mean square error of prediction (RMSEP) using three components for $Cu^{2+}$, $Ni^{2+}$ and $Zn^{2+}$ were 0.018, 0.010, 0.011 ppm, respectively. Figures of merit such as sensitivity, analytical sensitivity, limit of detection (LOD) were also estimated. High reliability was achieved when the proposed procedure was applied to simultaneous determination of $Cu^{2+}$, $Ni^{2+}$ and $Zn^{2+}$ in synthetic mixture and tap water.

Effect of sintering holding time on the properties and low-temperature degradation behaviour of manganese oxide-doped Y-TZP ceramic

S.M. Kwa,S. Ramesh,L.T. Bang,Y.H. Wong,W.J. Kelvin Chew,C.Y. Tan,J. Purbolaksono,H. Misran,W.D. Teng 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.2

The sintering of yttria-tetragonal zirconia polycrystals (Y-TZP) is commonly carried at a predefined temperature using a long holding time of 2 hours. This often has resulted in grain coarsening which affects the mechanical properties of the sintered body and low temperature degradation (LTD) behaviour of the ceramic when exposed to moist environment. In this research, the effect of using a short holding time of 1 min. during sintering coupled with small amounts (0.5 and 1 wt%) of manganese oxide, MnO2 as dopant on the mechanical properties and LTD behaviour of 3 mol% Y-TZP were investigated. The results showed that the mechanical properties improved significantly with the addition of 0.5 wt% MnO2 for the 1-min. and 12-min. holding time samples when compared to 2 hours holding time sintered at the same temperature of 1350 ℃. Nevertheless, regardless of the holding time employed, the 1 wt% MnO2 addition was not effective in improving the mechanical properties and ageing resistance of Y-TZP ceramic.