Displaying publications 1 - 20 of 450 in total

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  1. Zulkefeli M, Hisamatsu Y, Suzuki A, Miyazawa Y, Shiro M, Aoki S
    Chem Asian J, 2014 Oct;9(10):2831-41.
    PMID: 25080369 DOI: 10.1002/asia.201402513
    In our previous paper, we reported that a dimeric Zn(2+) complex with a 2,2'-bipyridyl linker (Zn2L(1)), cyanuric acid (CA), and a Cu(2+) ion automatically assemble in aqueous solution to form 4:4:4 complex 3, which selectively catalyzes the hydrolysis of mono(4-nitrophenyl)phosphate (MNP) at neutral pH. Herein, we report that the use of barbital (Bar) instead of CA for the self-assembly with Zn2L(1) and Cu(2+) induces 2:2:2 complexation of these components, and not the 4:4:4 complex, to form supramolecular complex 6 a, the structure and equilibrium characteristics of which were studied by analytical and physical measurements. The finding show that 6 a also accelerates the hydrolysis of MNP, similarly to 3. Moreover, inspired by the crystal structure of 6 a, we prepared barbital units that contain functional groups on their side chains in an attempt to produce supramolecular phosphatases that possess functional groups near the Cu2(μ-OH)2 catalytic core so as to mimic the catalytic center of alkaline phosphatase (AP).
    Matched MeSH terms: Water/chemistry
  2. Zhu T, Chong MN, Chan ES
    ChemSusChem, 2014 Nov;7(11):2974-97.
    PMID: 25274424 DOI: 10.1002/cssc.201402089
    The recent developments of nanostructured WO3 thin films synthesized through the electrochemical route of electrochemical anodization and cathodic electrodeposition for the application in photoelectrochemical (PEC) water splitting are reviewed. The key fundamental reaction mechanisms of electrochemical anodization and cathodic electrodeposition methods for synthesizing nanostructured WO3 thin films are explained. In addition, the effects of metal oxide precursors, electrode substrates, applied potentials and current densities, and annealing temperatures on size, composition, and thickness of the electrochemically synthesized nanostructured WO3 thin films are elucidated in detail. Finally, a summary is given for the general evaluation practices used to calculate the energy conversion efficiency of nanostructured WO3 thin films and a recommendation is provided to standardize the presentation of research results in the field to allow for easy comparison of reported PEC efficiencies in the near future.
    Matched MeSH terms: Water/chemistry*
  3. Zakaria ZA, Hussain MK, Mohamad AS, Abdullah FC, Sulaiman MR
    Biol Res Nurs, 2012 Jan;14(1):90-7.
    PMID: 21278166 DOI: 10.1177/1099800410395378
    Ficus deltoidea (Family Moraceae) leaves have been used traditionally by the Malays to treat ailments such as wounds, sores, and rheumatism. The aim of the present study was to determine the anti-inflammatory activity of the aqueous extract of F. deltoidea leaf (FDA) using acute and chronic inflammatory models. FDA, in the doses of 30, 100, and 300 mg/kg, was administered intraperitoneally in rats (n = 6) before the animals were subjected to the carrageenan-induced paw edema test, cotton pellet-induced granuloma test, and formalin test. The first two tests represent acute and chronic models of inflammation, respectively. The first and second phases of the formalin test represent neurogenic pain and inflammatory-mediated pain, respectively; thus, only the second phase was measured in the present study. Results showed that FDA exerted significant (p < .05) anti-inflammatory activity in all assays, with dose-response effects seen in the paw edema and formalin tests. In conclusion, the leaf of F. deltoidea possesses anti-inflammatory activity against acute and chronic inflammatory responses and against pain-associated inflammatory response. These findings justify the traditional uses of F. deltoidea leaves for treatment of inflammatory-mediated ailments.
    Matched MeSH terms: Water/chemistry
  4. Zakaria MR, Hirata S, Hassan MA
    Bioresour Technol, 2015 Jan;176:142-8.
    PMID: 25460995 DOI: 10.1016/j.biortech.2014.11.027
    The present works investigate hydrothermal pretreatment of oil palm empty fruit bunch and oil palm frond fiber in a batch tube reactor system with temperature and time range from 170 to 250°C and 10 to 20min, respectively. The behavior of soluble sugars, acids, furans, and phenols dramatically changed over treatment severities as determined by HPLC. The cellulose-rich treated solids were analyzed by SEM, WAXD, and BET surface area. Enzymatic hydrolysis was performed from both pretreated slurries and washed solid, and data obtained suggested that tannic acid derived from lignin degradation was a potential cellulase inhibitor. Both partial removal of hemicellulose and migration of lignin during hydrothermal pretreatment caused structural changes on the cellulose-hemicellulose-lignin matrix, resulting in the opening and expansion of specific surface area and pore volume. The current results provided important factors that maximize conversion of cellulose to glucose from oil palm biomass by hydrothermal process.
    Matched MeSH terms: Water/chemistry*
  5. Zakaria MR, Hirata S, Fujimoto S, Hassan MA
    Bioresour Technol, 2015 Oct;193:128-34.
    PMID: 26125612 DOI: 10.1016/j.biortech.2015.06.074
    Combined pretreatment with hot compressed water and wet disk milling was performed with the aim to reduce the natural recalcitrance of oil palm biomass by opening its structure and provide maximal access to cellulase attack. Oil palm empty fruit bunch and oil palm frond fiber were first hydrothermally pretreated at 150-190° C and 10-240 min. Further treatment with wet disk milling resulted in nanofibrillation of fiber which caused the loosening of the tight biomass structure, thus increasing the subsequent enzymatic conversion of cellulose to glucose. The effectiveness of the combined pretreatments was evaluated by chemical composition changes, power consumption, morphological alterations by SEM and the enzymatic digestibility of treated samples. At optimal pretreatment process, approximately 88.5% and 100.0% of total sugar yields were obtained from oil palm empty fruit bunch and oil palm frond fiber samples, which only consumed about 15.1 and 23.5 MJ/kg of biomass, respectively.
    Matched MeSH terms: Water/chemistry*
  6. Zainal-Abideen M, Aris A, Yusof F, Abdul-Majid Z, Selamat A, Omar SI
    Water Sci Technol, 2012;65(3):496-503.
    PMID: 22258681 DOI: 10.2166/wst.2012.561
    In this study of coagulation operation, a comparison was made between the optimum jar test values for pH, coagulant and coagulant aid obtained from traditional methods (an adjusted one-factor-at-a-time (OFAT) method) and with central composite design (the standard design of response surface methodology (RSM)). Alum (coagulant) and polymer (coagulant aid) were used to treat a water source with very low pH and high aluminium concentration at Sri-Gading water treatment plant (WTP) Malaysia. The optimum conditions for these factors were chosen when the final turbidity, pH after coagulation and residual aluminium were within 0-5 NTU, 6.5-7.5 and 0-0.20 mg/l respectively. Traditional and RSM jar tests were conducted to find their respective optimum coagulation conditions. It was observed that the optimum dose for alum obtained through the traditional method was 12 mg/l, while the value for polymer was set constant at 0.020 mg/l. Through RSM optimization, the optimum dose for alum was 7 mg/l and for polymer was 0.004 mg/l. Optimum pH for the coagulation operation obtained through traditional methods and RSM was 7.6. The final turbidity, pH after coagulation and residual aluminium recorded were all within acceptable limits. The RSM method was demonstrated to be an appropriate approach for the optimization and was validated by a further test.
    Matched MeSH terms: Water/chemistry*
  7. Zainal Z, Hui LK, Hussein MZ, Taufiq-Yap YH, Abdullah AH, Ramli I
    J Hazard Mater, 2005 Oct 17;125(1-3):113-20.
    PMID: 15996813
    The photodegradation of various dyes in aqueous solution was studied. Experiments were carried out using glass coated titanium dioxide thin film as photocatalyst. Photodegradation processes of methylene blue (MB), methyl orange (MO), indigo carmine (IC), chicago sky blue 6B (CSB), and mixed dye (MD, mixture of the four mentioned single dye) were reported. As each photodegradation system is pH dependent, the photodegradation experiment was carried out in each dye photodegradation reactive pH range at approximately 28 degrees C. The dyes removal efficiency was studied and compared using UV-vis spectrophotometer analysis. The total removal of each dye was: methylene blue (90.3%), methyl orange (98.5%), indigo carmine (92.4%), chicago sky blue 6B (60.3%), and mixed dyes (70.1%), respectively. The characteristic of the photocatalyst was investigated using X-ray diffractometer (XRD). The amount of each dye intermediate produced in the photodegradation process was also determined with the help of total organic carbon (TOC) analysis.
    Matched MeSH terms: Water/chemistry*
  8. Zailina H, Najibah H, Aiezzati AN, Praveena SM, Patimah I
    Biomed Res Int, 2014;2014:797603.
    PMID: 25530970 DOI: 10.1155/2014/797603
    A cross-sectional study was carried out to determine the arsenic (As) and cadmium (Cd) concentrations in blood, urine, and drinking water as well as the health implications on 100 residents in an urban and a rural community. Results showed the blood As, urinary Cd, DNA damage, and water As and Cs were significantly (P < 0.001) higher in the rural community. Findings showed significant (P < 0.005) correlations between blood As and DNA damage with household income, years of residence, and total glasses of daily water consumption among the rural residents. The urinary NAG concentrations, years of residence, milk powder intake (glass/week), and seafood intake (per week) were significantly correlated (P < 0.005) with urinary Cd concentrations among respondents. In addition, urinary Cd level significantly influenced the urinary NAG concentrations (P < 0.001). The rural respondents experienced significantly higher lymphocyte DNA damage and blood As influenced by their years of residence and water consumption. The Cd in drinking water also resulted in the rural respondents having significantly higher urinary NAG which had a significant relationship with urinary Cd.
    Matched MeSH terms: Drinking Water/chemistry*
  9. Yuzir A, Abdullah N, Chelliapan S, Sallis P
    Bioresour Technol, 2013 Apr;133:158-65.
    PMID: 23422308 DOI: 10.1016/j.biortech.2013.01.086
    The effects of Mecoprop (RS)-MCPP were investigated in an anaerobic membrane bioreactor (AnMBr) fed with synthetic wastewater containing stepwise increases in Mecoprop concentration, 5-200 mg L(-1) over 240 days. Effects were observed in terms of soluble chemical oxygen demand (COD) removal efficiency, volatile fatty acid (VFA) production, and methane yield. Soluble COD removal efficiency was stable at Mecoprop concentrations below 200 (±3) mg L(-1), with an average of 98 (±0.7)% removal. However, at 200 (±3) mg L(-1) Mecoprop, the COD removal efficiency decreased gradually to 94 (±1.5)%. At 5 mg L(-1) Mecoprop, acetic and propionic acid concentrations increased by 60% and 160%, respectively. In contrast, when Mecoprop was increased to 200 (±3) mg L(-1), the formation and degradation of acetate was unaffected by the higher Mecoprop concentration, acetate remaining below 35 mg L(-1). Increases in the Mecoprop specific utilization rate were observed as Mecoprop was increased stepwise between 5 and 200 mg L(-1).
    Matched MeSH terms: Waste Water/chemistry*
  10. Yusri NM, Chan KW, Iqbal S, Ismail M
    Molecules, 2012 Oct 25;17(11):12612-21.
    PMID: 23099617 DOI: 10.3390/molecules171112612
    A sequential solvent extraction scheme was employed for the extraction of antioxidant compounds from kenaf (Hibiscus cannabinus L.) seeds. Yield of extracts varied widely among the solvents and was the highest for hexane extract (16.6% based on dry weight basis), while water extract exhibited the highest total phenolic content (18.78 mg GAE/g extract), total flavonoid content (2.49 mg RE/g extract), and antioxidant activities (p < 0.05). DPPH and hydroxyl radical scavenging, β-carotene bleaching, metal chelating activity, ferric thiocyanate and thiobarbituric acid reactive substances assays were employed to comprehensively assess the antioxidant potential of different solvent extracts prepared sequentially. Besides water, methanolic extract also exhibited high retardation towards the formation of hydroperoxides and thiobarbituric acid reactive substances in the total antioxidant activity tests (p < 0.05). As conclusion, water and methanol extracts of kenaf seed may potentially serve as new sources of antioxidants for food and nutraceutical applications.
    Matched MeSH terms: Water/chemistry
  11. Yusof AM, Malek NA, Kamaruzaman NA, Adil M
    Environ Technol, 2010 Jan;31(1):41-6.
    PMID: 20232677 DOI: 10.1080/09593330903313794
    Zeolites P in sodium (NaP) and potassium (KP) forms were used as adsorbents for the removal of calcium (Ca2+) and zinc (Zn2+) cations from aqueous solutions. Zeolite KP was prepared by ion exchange of K+ with Na+ which neutralizes the negative charge of the zeolite P framework structure. The ion exchange capacity of K+ on zeolite NaP was determined through the Freundlich isotherm equilibrium study. Characterization of zeolite KP was determined using infrared spectroscopy and X-ray diffraction (XRD) techniques. From the characterization, the structure of zeolite KP was found to remain stable after the ion exchange process. Zeolites KP and NaP were used for the removal of Ca and Zn from solution. The amount of Ca2+ and Zn2+ in aqueous solution before and after the adsorption by zeolites was analysed using the flame atomic absorption spectroscopy method. The removal of Ca2+ and Zn2+ followed the Freundlich isotherm rather than the Langmuir isotherm model. This result also revealed that zeolite KP adsorbs Ca2+ and Zn2+ more than zeolite NaP and proved that modification of zeolite NaP with potassium leads to an increase in the adsorption efficiency of the zeolite. Therefore, the zeolites NaP and KP can be used for water softening (Ca removal) and reducing water pollution/toxicity (Zn removal).
    Matched MeSH terms: Water/chemistry*
  12. You KY, Mun HK, You LL, Salleh J, Abbas Z
    Sensors (Basel), 2013;13(3):3652-63.
    PMID: 23493127 DOI: 10.3390/s130303652
    A moisture detection of single rice grains using a slim and small open-ended coaxial probe is presented. The coaxial probe is suitable for the nondestructive measurement of moisture values in the rice grains ranging from from 9.5% to 26%. Empirical polynomial models are developed to predict the gravimetric moisture content of rice based on measured reflection coefficients using a vector network analyzer. The relationship between the reflection coefficient and relative permittivity were also created using a regression method and expressed in a polynomial model, whose model coefficients were obtained by fitting the data from Finite Element-based simulation. Besides, the designed single rice grain sample holder and experimental set-up were shown. The measurement of single rice grains in this study is more precise compared to the measurement in conventional bulk rice grains, as the random air gap present in the bulk rice grains is excluded.
    Matched MeSH terms: Water/chemistry*
  13. Yiin CL, Quitain AT, Yusup S, Sasaki M, Uemura Y, Kida T
    Bioresour Technol, 2016 Jan;199:258-264.
    PMID: 26253419 DOI: 10.1016/j.biortech.2015.07.103
    The aim of this work was to characterize the natural low transition temperature mixtures (LTTMs) as promising green solvents for biomass pretreatment with the critical characteristics of cheap, biodegradable and renewable, which overcome the limitations of ionic liquids (ILs). The LTTMs were derived from inexpensive commercially available hydrogen bond acceptor (HBA) and l-malic acid as the hydrogen bond donor (HBD) in distinct molar ratios of starting materials and water. The peaks involved in the H-bonding shifted and became broader for the OH groups. The thermal properties of the LTTMs were not affected by water while the biopolymers solubility capacity of LTTMs was improved with the increased molar ratio of water and treatment temperature. The pretreatment of oil palm biomass was consistence with the screening on solubility of biopolymers. This work provides a cost-effective alternative to utilize microwave hydrothermal extracted green solvents such as malic acid from natural fruits and plants.
    Matched MeSH terms: Water/chemistry
  14. Yee CN, Ooi CHR, Tan LP, Misran M, Tang NT
    PLoS One, 2019;14(3):e0213697.
    PMID: 30913207 DOI: 10.1371/journal.pone.0213697
    That water may not be an inert medium was indicated by the presence at water's interfaces a negatively charged solute free zone of several hundred microns in thickness called the exclusion zone (EZ). Further evidence was demonstrated by Ovchinnikova's experiments (2009) showing that water can store and release substantial amount of charge. We demonstrate that the charge storage capacity of water arises from highly stable large-scale ionic structures with measurable charge imbalances and discrete levels of charge density. We also show evidence that the charge zones formation requires ionic solutes, and their formation correlate to large change in conductivity, by as much as 250%. Our experiments indicate that large-scale structuring plays a pivotal role in electrolysis and conductivity in ionic solution. We propose that water is an electrochemically active medium and present a new model of electrolysis and conductivity in ionic solution.
    Matched MeSH terms: Water/chemistry
  15. Yeap PK, Lim KO, Chong CS, Teng TT
    Chem Phys Lipids, 2008 Jan;151(1):1-9.
    PMID: 17963698
    As the packing structure of lipid molecules in the liposomes will vary in the presence of ions, it is expected that the density of lipid and the effective volume of lipid molecules in the dispersions will also vary, albeit minutely. Density measurements of lipid-water dispersions with the addition of Ca(2+) ions were determined accurately. The effect of Ca(2+) ions on the molecular packing structure of the liposomes was elucidated from the results obtained. The results for the density of the lecithin in the dispersions with and without the addition of Ca(2+) ions are, respectively, 1.0782 and 1.0579 g cm(-3) at 25 degrees C; and 1.0048 and 0.9961 g cm(-3) at 50 degrees C. The average values of the effective molecular volume of lecithin in the dispersions with and without the addition of Ca(2+) ions are, respectively, 1.131E-21 and 1.152E-21 cm(3) at 25 degrees C; and 1.213E-21 and 1.224E-21 cm(3) at 50 degrees C.
    Matched MeSH terms: Water/chemistry
  16. Yavari S, Malakahmad A, Sapari NB, Yavari S
    Water Sci Technol, 2017 Apr;75(7-8):1684-1692.
    PMID: 28402310 DOI: 10.2166/wst.2017.043
    Phytoremediation is an environmentally friendly and sustainable alternative for treatment of nitrogen-enriched wastewaters. In this study, Ta-khian (Hopea odorata) and Lagos mahogany (Khaya ivorensis), two tropical timber plants, were investigated for their performances in treatment of urea manufacturing factory effluent with high nitrogen (N) content. Plant seedlings received four concentrations of N (190, 240, 290 and 340 mg/L N) in laboratory-scale constructed wetlands every 4 days for a duration of 8 weeks. The solution volumes supplied to each container, amount of N recovered by plants and plant growth characteristics were measured throughout the experiment. Results showed that Ta-khian plants were highly effective at reducing N concentration and volume of water. A maximum of 63.05% N recovery was obtained by Ta-khian plants grown in 290 mg/L N, which was assimilated in the chlorophyll molecule structure and shoot biomass. Significant positive correlations have been shown between N recovery percentages and plant growth parameters. Ta-Khian plants can be applied as suitable phytoremediators for mitigating N pollution in water sources.
    Matched MeSH terms: Waste Water/chemistry
  17. Yau XH, Khe CS, Mohamed Saheed MS, Lai CW, You KY, Tan WK
    PLoS One, 2020;15(4):e0232490.
    PMID: 32353051 DOI: 10.1371/journal.pone.0232490
    Oily wastewater, especially water-oil emulsion has become serious environmental issue and received global attention. Chemical demulsifiers are widely used to treat oil-water emulsion, but the toxicity, non-recyclable and non-environmental friendly characteristic of chemical demulsifiers had limited their practical application in oil-water separation. Therefore, it is imperative to develop an efficient, simple, eco-friendly and recyclable demulsifiers for breaking up the emulsions from the oily wastewater. In this study, a magnetic demulsifier, magnetite-reduced graphene oxide (M-rGO) nanocomposites were proposed as a recyclable demulsifier to break up the surfactant stabilized crude oil-in-water (O/W) emulsion. M-rGO nanocomposites were prepared via in situ chemical synthesis by using only one type Fe salt and GO solid as precursor at room temperature. The prepared composites were fully characterized by various techniques. The effect of demulsifier dosage and pH of emulsion on demulsification efficiency (ED) has been studied in detailed. The demulsification mechanism was also proposed in this study. Results showed that M-rGO nanocomposites were able to demulsify crude O/W emulsion. The ED reaches 99.48% when 0.050 wt.% of M-rGO nanocomposites were added to crude O/W emulsion (pH = 4). Besides, M-rGO nanocomposites can be recycled up to 7 cycles without showing a significant change in terms of ED. Thus, M-rGO nanocomposite is a promising demulsifier for surfactant stabilized crude O/W emulsion.
    Matched MeSH terms: Waste Water/chemistry*
  18. Yarmand H, Gharehkhani S, Kazi SN, Sadeghinezhad E, Safaei MR
    ScientificWorldJournal, 2014;2014:369593.
    PMID: 25254236 DOI: 10.1155/2014/369593
    Thermal characteristics of turbulent nanofluid flow in a rectangular pipe have been investigated numerically. The continuity, momentum, and energy equations were solved by means of a finite volume method (FVM). The symmetrical rectangular channel is heated at the top and bottom at a constant heat flux while the sides walls are insulated. Four different types of nanoparticles Al2O3, ZnO, CuO, and SiO2 at different volume fractions of nanofluids in the range of 1% to 5% are considered in the present investigation. In this paper, effect of different Reynolds numbers in the range of 5000 < Re < 25000 on heat transfer characteristics of nanofluids flowing through the channel is investigated. The numerical results indicate that SiO2-water has the highest Nusselt number compared to other nanofluids while it has the lowest heat transfer coefficient due to low thermal conductivity. The Nusselt number increases with the increase of the Reynolds number and the volume fraction of nanoparticles. The results of simulation show a good agreement with the existing experimental correlations.
    Matched MeSH terms: Water/chemistry*
  19. Yap CL, Gan S, Ng HK
    J Environ Sci (China), 2012;24(6):1064-75.
    PMID: 23505874
    Solubility data of recalcitrant contaminants in cosolvents is essential to determine their potential applications in enhanced soil remediation. The solubilities of phenanthrene, anthracene, fluoranthene and benzo[a]pyrene in ethyl lactate/water and ethanol/water mixtures were measured using equilibrium techniques. The cosolvency powers derived from solubility data were then applied to the model developed from the solvophobic approach to predict the capability of ethyl lactate and ethanol in enhancing the desorption of contaminants from soils. Both ethyl lactate and ethanol cosolvents were shown to be able to enhance the solubilisation of the tested four polycyclic aromatic hydrocarbons by > 4 orders of magnitude above the levels obtained with water alone. However, ethyl lactate demonstrated a greater capacity to enhance PAH solubility than ethanol. The cosolvency powers of ethyl lactate/water system obtained from the end-to-end slope (sigma) and the end-to-half slope (sigma0.5) of the solubilisation curve were 1.0-1.5 and 2.0-2.9 higher than ethanol/water system respectively. In line with this, ethyl lactate/water was demonstrated to enhance the desorption of contaminants from soil by 20%-37% and 18%-61% higher compared to ethanol/water system in low organic content and high organic content soils respectively, with a 2:1 (V/W) ratio of solution:soil and with cosolvent fraction as low as 0.4. With the exception of benzo[a]pyrene, the experimental desorption results agreed fairly with the predicted values, under an applied solution:soil ratio that was enough to hold the capacity of released contaminants.
    Matched MeSH terms: Water/chemistry
  20. Yang J, Qiu C, Li G, Lee WJ, Tan CP, Lai OM, et al.
    Food Chem, 2020 Oct 15;327:127014.
    PMID: 32434126 DOI: 10.1016/j.foodchem.2020.127014
    The influence of diacylglycerol (DAG) combined with polyglycerol polyricinoleate (PGPR) on the stability of water-in-oil (W/O) emulsions containing hydrogenated palm oil (HPO) was studied. Polarized light microscope revealed that DAG promoted HPO to crystallize at the water-oil interface, providing the combination of Pickering and network stabilization effects. It was proposed that the molecular compatibility of fatty acids in DAG with HPO accounted for the promotional effect. The interfacial crystallization of DAG together with the surface activity of PGPR led to the formation of emulsions with uniform small droplets and high freeze-thaw stability. Further exploration of physical properties indicated that the combination of DAG and PGPR dramatically improved the emulsion's viscoelasticity and obtained a larger deformation yield. Water droplets in DAG-based emulsions acted as active fillers to improve the network rigidity. Therefore, DAG is a promising material to be used as emulsifier to enhance the physical stability of W/O emulsions.
    Matched MeSH terms: Water/chemistry
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