Displaying publications 61 - 80 of 117 in total

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  1. Ardo FM, Khoo KS, Ahmad Sobri MZ, Suparmaniam U, Ethiraj B, Anwar AF, et al.
    Environ Pollut, 2024 Apr 01;346:123648.
    PMID: 38408504 DOI: 10.1016/j.envpol.2024.123648
    Municipal wastewater is ubiquitously laden with myriad pollutants discharged primarily from a combination of domestic and industrial activities. These heterogeneous pollutants are threating the natural environments when the traditional activated sludge system fails sporadically to reduce the pollutants' toxicities. Besides, the activated sludge system is very energy intensive, bringing conundrums for decarbonization. This research endeavoured to employ Chlorella vulgaris sp. In converting pollutants from municipal wastewater into hydrogen via alternate light and dark fermentative process. The microalgae in attached form onto 1 cm3 of polyurethane foam cubes were adopted in optimizing light intensity and photoperiod during the light exposure duration. The highest hydrogen production was recorded at 52 mL amidst the synergistic light intensity and photoperiod of 200 μmolm-2s-1 and 12:12 h (light:dark h), respectively. At this lighting condition, the removals of chemical oxygen demand (COD) and ammoniacal nitrogen were both achieved at about 80%. The sustainability of microalgal fermentative performances was verified in recyclability study using similar immobilization support material. There were negligible diminishments of hydrogen production as well as both COD and ammoniacal nitrogen removals after five cycles, heralding inconsequential microalgal cells' washout from the polyurethane support when replacing the municipal wastewater medium at each cycle. The collected dataset was finally modelled into enhanced Monod equation aided by Python software tool of machine learning. The derived model was capable to predict the performances of microalgae to execute the fermentative process in producing hydrogen while subsisting municipal wastewater at arbitrary photoperiod. The enhanced model had a best fitting of R2 of 0.9857 as validated using an independent dataset. Concisely, the outcomes had contributed towards the advancement of municipal wastewater treatment via microalgal fermentative process in producing green hydrogen as a clean energy source to decarbonize the wastewater treatment facilities.
    Matched MeSH terms: Ammonium Compounds*
  2. Daood U, Gopinath D, Pichika MR, Mak KK, Seow LL
    Molecules, 2021 Apr 12;26(8).
    PMID: 33921378 DOI: 10.3390/molecules26082214
    To determine whether quaternary ammonium (k21) binds to Severe Acute Respiratory Syndrome-Coronavirus 2 (SARS-CoV-2) spike protein via computational molecular docking simulations, the crystal structure of the SARS-CoV-2 spike receptor-binding domain complexed with ACE-2 (PDB ID: 6LZG) was downloaded from RCSB PD and prepared using Schrodinger 2019-4. The entry of SARS-CoV-2 inside humans is through lung tissues with a pH of 7.38-7.42. A two-dimensional structure of k-21 was drawn using the 2D-sketcher of Maestro 12.2 and trimmed of C18 alkyl chains from all four arms with the assumption that the core moiety k-21 was without C18. The immunogenic potential of k21/QA was conducted using the C-ImmSim server for a position-specific scoring matrix analyzing the human host immune system response. Therapeutic probability was shown using prediction models with negative and positive control drugs. Negative scores show that the binding of a quaternary ammonium compound with the spike protein's binding site is favorable. The drug molecule has a large Root Mean Square Deviation fluctuation due to the less complex geometry of the drug molecule, which is suggestive of a profound impact on the regular geometry of a viral protein. There is high concentration of Immunoglobulin M/Immunoglobulin G, which is concomitant of virus reduction. The proposed drug formulation based on quaternary ammonium to characterize affinity to the SARS-CoV-2 spike protein using simulation and computational immunological methods has shown promising findings.
    Matched MeSH terms: Quaternary Ammonium Compounds/metabolism*; Quaternary Ammonium Compounds/chemistry
  3. Shaari AL, Surif M, Latiff FA, Omar WM, Ahmad MN
    Trop Life Sci Res, 2011 May;22(1):51-69.
    PMID: 24575209
    Many reports have revealed that the abundance of microalgae in shrimp ponds vary with changes in environmental factors such as light, temperature, pH, salinity and nutrient level throughout a shrimp culture period. In this study, shrimp cultivation period was divided into three stages (initial = week 0-5, mid = week 6-10 and final = week 11-15). Physical and chemical parameters throughout the cultivation period were studied and species composition of microalgae was monitored. Physical parameters were found to fluctuate widely with light intensity ranging between 182.23-1278 μmol photon m(-2)s(-1), temperature between 29.56°C -31.59°C, dissolved oxygen (DO) between 4.56-8.21 mg/l, pH between 7.65-8.49 and salinity between 20‰-30‰. Ammonium (NH4 (+)-N), nitrite (NO2 (-)-N), nitrate (NO3 (-)-N), and orthophosphate (PO4 (3-)-P) concentrations in the pond at all cultivation stages ranged from 0.017 to 0.38 mg/l, 0.24 to 2.12 mg/l, 0.06 to 0.98 mg/l and 0.16 to 1.93 mg/l respectively. Statistical test (ANOVA) showed that there were no significant difference (p<0.05) in nutrients concentrations among the cultivation stages. All nutrients concentrations however were still in the tolerable level and safe for shrimp culture. The chlorophyll a contents were found to range from 5.03±2.17 to 32.61±0.35 μg/l throughout the cultivation period. A total of 19 microalgae species were found in the shrimp pond, with diatoms contributing up to 72% of the species followed by Chlorophyta (11%) and Cyanophyta (11%). However, weekly species abundance varied through the study period. At the initial stage, when there were no shrimps in the pond, Anabaena spp. and Oscillatoria spp. (Cyanophyta) were the dominant species, followed by Chlorella sp. and Dunaliella sp. (Chlorophyta). When shrimps were introduced into the pond, Amphora sp., Navicula sp. Gyrosigma sp. and Nitzschia sp. (diatoms) started to exist. At the middle and towards the final stage of the shrimp culture period diatoms were the dominant species. The Chlorophyta (Chlorella sp.) domination took place only twice, which was at week 2 and 13. The absence of some of the coastal water microalgae species in the shrimp pond was most likely due to the fact that they could not tolerate the physicochemical factors of harsh environment. In this study, Cylindrotheca closterium was regarded as the most tolerant species among the microalgae due to its ability to exist for 6 weeks out of the 15 weeks of cultivation.
    Matched MeSH terms: Ammonium Compounds
  4. Asma Liyana Shaari, Misni Surif, Faazaz Abd. Latiff, Wan Maznah Wan Omar, Mohd Noor Ahmad
    Trop Life Sci Res, 2011;22(1):-.
    MyJurnal
    Many reports have revealed that the abundance of microalgae in shrimp ponds vary with changes in environmental factors such as light, temperature, pH, salinity and nutrient level throughout a shrimp culture period. In this study, shrimp cultivation period was divided into three stages (initial = week 0–5, mid = week 6–10 and final = week 11–15). Physical and chemical parameters throughout the cultivation period were studied and species composition of microalgae was monitored. Physical parameters were found to
    fluctuate widely with light intensity ranging between 182.23–1278 µmol photon m–2s–1, temperature between 29.56ºC –31.59ºC, dissolved oxygen (DO) between 4.56–8.21 mg/l, pH between 7.65–8.49 and salinity between 20‰–30‰. Ammonium (NH4+-N), nitrite (NO2– -N), nitrate (NO3– -N), and orthophosphate (PO43– -P) concentrations in the pond at all cultivation stages ranged from 0.017 to 0.38 mg/l, 0.24 to 2.12 mg/l, 0.06 to 0.98 mg/l and 0.16 to 1.93 mg/l respectively. Statistical test (ANOVA) showed that there were no significant difference (p
    Matched MeSH terms: Ammonium Compounds
  5. Sohaimy MIHA, Isa MINM
    Polymers (Basel), 2020 Oct 26;12(11).
    PMID: 33114745 DOI: 10.3390/polym12112487
    Green and safer materials in energy storage technology are important right now due to increased consumption. In this study, a biopolymer electrolyte inspired from natural materials was developed by using carboxymethyl cellulose (CMC) as the core material and doped with varied ammonium carbonate (AC) composition. X-ray diffraction (XRD) shows the prepared CMC-AC electrolyte films exhibited low crystallinity content, Xc (~30%) for sample AC7. A specific wavenumber range between 900-1200 cm-1 and 1500-1800 cm-1 was emphasized in Fourier transform infrared (FTIR) testing, as this is the most probable interaction to occur. The highest ionic conductivity, σ of the electrolyte system achieved was 7.71 × 10-6 Scm-1 and appeared greatly dependent on ionic mobility, µ and diffusion coefficient, D. The number of mobile ions, η, increased up to the highest conducting sample (AC7) but it became less prominent at higher AC composition. The transference measurement, tion showed that the electrolyte system was predominantly ionic with sample AC7 having the highest value (tion = 0.98). Further assessment also proved that the H+ ion was the main conducting species in the CMC-AC electrolyte system, which presumably was due to protonation of ammonium salt onto the complexes site and contributed to the overall ionic conductivity enhancement.
    Matched MeSH terms: Ammonium Compounds
  6. Barakat A, Al-Majid AM, Soliman SM, Lotfy G, Ghabbour HA, Fun HK, et al.
    Molecules, 2015;20(11):20642-58.
    PMID: 26610441 DOI: 10.3390/molecules201119710
    The synthesis of the new diethyl ammonium salt of diethylammonium(E)-5-(1,5-bis(4-fluorophenyl)-3-oxopent-4-en-1-yl)-1,3-diethyl-4,6-dioxo-2-thioxohexaydropyrimidin-5-ide 3 via a regioselective Michael addition of N,N-diethylthiobarbituric acid 1 to dienone 2 is described. In 3, the carboanion of the thiobarbituric moiety is stabilized by the strong intramolecular electron delocalization with the adjacent carbonyl groups and so the reaction proceeds without any cyclization. The molecular structure investigations of 3 were determined by single-crystal X-ray diffraction as well as DFT computations. The theoretically calculated (DFT/B3LYP) geometry agrees well with the crystallographic data. The effect of fluorine replacement by chlorine atoms on the molecular structure aspects were investigated using DFT methods. Calculated electronic spectra showed a bathochromic shift of the π-π* transition when fluorine is replaced by chlorine. Charge decomposition analyses were performed to study possible interaction between the different fragments in the studied systems. Molecular docking simulations examining the inhibitory nature of the compound show an anti-diabetic activity with Pa (probability of activity) value of 0.229.
    Matched MeSH terms: Ammonium Compounds
  7. Fadhullah W, Yaccob NS, Syakir MI, Muhammad SA, Yue FJ, Li SL
    Sci Total Environ, 2020 Jan 15;700:134517.
    PMID: 31629263 DOI: 10.1016/j.scitotenv.2019.134517
    Nitrate is one of the primary nutrients associated with sedimentation and fuels eutrophication in reservoir systems. In this study, water samples from Bukit Merah Reservoir (BMR) were analysed using a combination of water chemistry, water stable isotopes (δ2H-H2O and δ18O-H2O) and nitrate stable isotopes (δ15N-NO3- and δ18O-NO3-). The objective was to evaluate nitrate sources and processes in BMR, the oldest man-made reservoir in Malaysia. The δ15N-NO3- values in the river and reservoir water samples were in the range +0.4 to +14.9‰ while the values of δ18O-NO3- were between -0.01 and +39.4‰, respectively. The dual plots of δ15N-NO3- and δ18O-NO3- reflected mixing sources from atmospheric deposition (AD) input, ammonium in fertilizer/rain, soil nitrogen, and manure and sewage (MS) as the sources of nitrate in the surface water of BMR. Nitrate stable isotopes suggested that BMR undergoes processes such as nitrification and mixing. Denitrification and assimilation were not prevalent in the system. The Bayesian mixing model highlighted the dominance of MS sources in the system while AD contributed more proportion in the reservoir during both seasons than in the river. The use of δ13C, δ15N, and C:N ratios enabled the identification of terrestrial sources of the organic matter in the sediment, enhancing the understanding of sedimentation associated with nutrients previously reported in BMR. Overall, the nitrate sources and processes should be considered in decision-making in the management of the reservoir for irrigation, Arowana fish culture and domestic water supply.
    Matched MeSH terms: Ammonium Compounds
  8. Yusof N, Hassan MA, Yee PL, Tabatabaei M, Othman MR, Mori M, et al.
    Waste Manag Res, 2011 Jun;29(6):602-11.
    PMID: 21447612 DOI: 10.1177/0734242X10397581
    Nitrification of mature sanitary landfill leachate with high-strength of N-NH(4) + (1080-2350 mg L(-1)) was performed in a 10 L continuous nitrification activated sludge reactor. The nitrification system was acclimatized with synthetic leachate during feed batch operation to avoid substrate inhibition before being fed with actual mature leachate. Successful nitrification was achieved with an approximately complete ammonium removal (99%) and 96% of N-NH(4) + conversion to N-NO(-) (3) . The maximum volumetric and specific nitrification rates obtained were 2.56 kg N-NH(4) (+) m(-3) day(-1) and 0.23 g N-NH(4) ( +) g(-1) volatile suspended solid (VSS) day(-1), respectively, at hydraulic retention time (HRT) of 12.7 h and solid retention time of 50 days. Incomplete nitrification was encountered when operating at a higher nitrogen loading rate of 3.14 kg N-NH(4) (+) m(-3) day(-1). The substrate overloading and nitrifiers competition with heterotrophs were believed to trigger the incomplete nitrification. Fluorescence in situ hybridization (FISH) results supported the syntrophic association between the ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria. FISH results also revealed the heterotrophs as the dominant and disintegration of some AOB cell aggregates into single cells which further supported the incomplete nitrification phenomenon.
    Matched MeSH terms: Quaternary Ammonium Compounds/metabolism*
  9. Abdul-Rahman R, Tsuno H, Zainol N
    Water Sci Technol, 2002;45(12):197-204.
    PMID: 12201103
    Elevated levels of nutrients in agroindustry wastewaters, and higher reliance on chlorination pose health threats due to formation of chlorinated organics as well as increased chlorination costs. Removals of ammonium and nitrate compounds were studied using activated carbon from palm shells, as adsorbent and support media. Experiments were carried out at several loadings, F:M from 0.31 to 0.58, and hydraulic residence times (HRT) of 24 h, 12 h and 8 h. Results show that the wastewater treatment process achieved removals of over 90% for COD and 62% for Total-N. Studies on removals from river water were carried out in sequencing batch reactor (SBR) and activated carbon biofilm (ACB) reactor. Removals achieved by the SBR adsorption-biodegradation combination were 67.0% for COD, 58.8% for NH3-N and 25.5% for NO3-N while for adsorption alone the removals were only 37.0% for COD, 35.2% for NH3-N and 13.8% for NO3-N. In the ACB reactor, at HRT of 1.5 to 6 h, removals ranged from 12.5 to 100% for COD, 16.7 to 100% for NO3-N and 13.5 to 100% for NH3-N. Significant decrease in removals was shown at lower HRT. The studies have shown that substantial removals of COD, NO3-N and NH3-N from both wastewater and river water may be achieved via adsorption-biodegradation by biofilm on activated carbon processes.
    Matched MeSH terms: Quaternary Ammonium Compounds/metabolism; Quaternary Ammonium Compounds/chemistry*
  10. Leong CC, Shen TC
    Plant Physiol, 1982 Dec;70(6):1762-3.
    PMID: 16662758
    Nitrate reductase inhibitor is usually found in the roots of rice plants (Oryza sativa L. cv MR7), but it was also produced in the shoots of aging plants. The inhibitor was inducible in the shoot of rice seedlings by dark, minus-nitrate or plus-ammonium treatments. There appears to be a general involvement of the inhibitor in the control of nitrate assimilation in the plant.
    Matched MeSH terms: Ammonium Compounds
  11. Lee LY, Morad N, Ismail N, Talebi A, Rafatullah M
    Int J Mol Sci, 2020 Sep 18;21(18).
    PMID: 32962106 DOI: 10.3390/ijms21186860
    This study investigates the separation of two heavy metals, Cd(II) and Cu(II), from the mixed synthetic feed using a liquid-liquid extraction. The current study uses tri-octyl methylammonium chloride (Aliquat 336) as the extractant (with tributyl phosphate (TBP) as a phase modifier), diluted in toluene, in order to investigate the selective extraction of Cd(II) over Cu(II) ions. We investigate the use of ethylenediaminetetraacetic acid (EDTA) as a masking agent for Cu(II), when added in aqueous feed, for the selective extraction of Cd(II). Five factors that influence the selective extraction of Cd(II) over Cu(II) (the equilibrium pH (pHeq), Aliquat 336 concentration (Aliquat 336), TBP concentration (TBP), EDTA concentration (EDTA), and organic to aqueous ratio (O:A)) were analyzed. Results from a 25-1 fractional factorial design show that Aliquat 336 significantly influenced Cd(II) extraction, whereas EDTA was statistically significant for the antagonistic effect on the E% of Cu(II) in the same system. Moreover, results from optimization experiment showed that the optimum conditions are Aliquat 336 concentration of 99.64 mM and EDTA concentration of 48.86 mM-where 95.89% of Cd(II) was extracted with the least extracted Cu(II) of 0.59%. A second-order model was fitted for optimization of Cd(II) extraction with a R2 value of 0.998, and ANOVA results revealed that the model adequately fitted the data at a 5% significance level. Interaction between Aliquat 336 and Cd(II) has been proven via FTIR qualitative analysis, whereas the addition of TBP does not affect the extraction mechanism.
    Matched MeSH terms: Quaternary Ammonium Compounds/chemistry
  12. Hilles AH, Abu Amr SS, Hussein RA, Arafa AI, El-Sebaie OD
    Water Sci Technol, 2016;73(1):102-12.
    PMID: 26744940 DOI: 10.2166/wst.2015.468
    The objective of this study was to investigate the performance of employing H2O2 reagent in persulfate activation to treat stabilized landfill leachate. A central composite design (CCD) with response surface methodology (RSM) was applied to evaluate the relationships between operating variables, such as persulfate and H2O2 dosages, pH, and reaction time, to identify the optimum operating conditions. Quadratic models for the following two responses proved to be significant with very low probabilities (<0.0001): chemical oxygen demand (COD) and NH3-N removal. The obtained optimum conditions included a reaction time of 116 min, 4.97 g S2O8(2-), 7.29 g H2O2 dosage and pH 11. The experimental results were corresponding well with predicted models (COD and NH3-N removal rates of 81% and 83%, respectively). The results obtained in the stabilized leachate treatment were compared with those from other treatment processes, such as persulfate only and H2O2 only, to evaluate its effectiveness. The combined method (i.e., /S2O8(2-)/H2O2) achieved higher removal efficiencies for COD and NH3-N compared with other studied applications.
    Matched MeSH terms: Ammonium Compounds/isolation & purification*
  13. Jamulidin, S.N.K., Manogaran. M., Yakasai, M.H., Rahman, M.F.A., Shukor, M.Y.
    MyJurnal
    In this study, a novel glyphosate-degrading shows the ability to reduce molybdenum to
    molybdenum blue. The enzyme from this bacterium was partially purified and partially
    characterized to ascertain whether the Mo-reducing enzyme from this bacterium shows better or
    lower efficiency in reducing molybdenum compared to other Mo-reducing bacterium that only
    exhibits a single biotransformation activity. The enzyme was partially purified using ammonium
    sulphate fractionation. The Vmax for the electron donating substrate or NADH was at 1.905 nmole
    Mo blue/min while the Km was 6.146 mM. The regression coefficient was 0.98. Comparative
    assessment with the previously characterized Mo-reducing enzyme from various bacteria showed
    that the Mo-reducing enzyme from Burkholderia vietnamiensis strain AQ5-12 showed a lower
    enzyme activity.
    Matched MeSH terms: Ammonium Compounds
  14. Noraziah Mohamad Zin, Marlini Othman
    MyJurnal
    Bakteria endofit adalah berpotensi untuk menghasilkan antibiotik dan metabolit sekunder yang lain. Penghasilan metabolit sekunder dapat ditingkatkan melalui pengoptimuman kandungan nutrien seperti sumber nitrogen. Dalam kajian ini kandungan sumber nitrogen iaitu ammonium sulfat, ammonium dihidrogen fosfat, kalium nitrat dan natrum nitrat telah diubahsuai di dalam kaldu International Streptomyces Project 4 (ISP4) untuk pertumbuhan Streptomyces SUK 02. Pengekstrakan dilakukan dengan menggunakan etil asetat dan aktiviti antifungus ditentukan dengan menggunakan teknik serapan agar. Fungus ujian yang digunakan adalah Aspergillus fumigatus dan Fusarium solani. Hasil kajian menunjukkan peratusan berat (w/v) ekstrak kasar maksima didapati daripada kaldu yang mengandungi natrium nitrat (3.30%), diikuti oleh ammonium dihidrogen fosfat (2.24%), ammonium sulfat (1.46%) dan kalium nitrat (1.20%). Aktiviti antifungus dikesan daripada ekstrak bersumberkan nitrogen ammonium sulfat.Peratus perencatan ekstrak tersebut terhadap Aspergillus fumigatus dan Fusarium solani adalah 33.0-35.0% dan 17.4-30.0%, masing-masing. Manakala nilai MIC terhadap Aspergillus fumigatus adalah 1.5 mg/ml. Sebagai kesimpulan, natrium nitrat merupakan sumber nitrogen yang sesuai bagi partumbuhan optimum Streptomyces SUK 02 manakala kehadiran ammonium sulfat boleh meningkatkan aktiviti antifungus.
    Matched MeSH terms: Ammonium Compounds
  15. Lai CW
    ScientificWorldJournal, 2014;2014:843587.
    PMID: 24782669 DOI: 10.1155/2014/843587
    Tungsten trioxide (WO₃) possesses a small band gap energy of 2.4-2.8 eV and is responsive to both ultraviolet and visible light irradiation including strong absorption of the solar spectrum and stable physicochemical properties. Thus, controlled growth of one-dimensional (1D) WO₃ nanotubular structures with desired length, diameter, and wall thickness has gained significant interest. In the present study, 1D WO₃ nanotubes were successfully synthesized via electrochemical anodization of tungsten (W) foil in an electrolyte composed of 1 M of sodium sulphate (Na₂SO₄) and ammonium fluoride (NH₄F). The influence of NH₄F content on the formation mechanism of anodic WO₃ nanotubular structure was investigated in detail. An optimization of fluoride ions played a critical role in controlling the chemical dissolution reaction in the interface of W/WO₃. Based on the results obtained, a minimum of 0.7 wt% of NH₄F content was required for completing transformation from W foil to WO₃ nanotubular structure with an average diameter of 85 nm and length of 250 nm within 15 min of anodization time. In this case, high aspect ratio of WO₃ nanotubular structure is preferred because larger active surface area will be provided for better photocatalytic and photoelectrochemical (PEC) reactions.
    Matched MeSH terms: Quaternary Ammonium Compounds/chemistry
  16. Riaz N, Bustam MA, Chong FK, Man ZB, Khan MS, Shariff AM
    ScientificWorldJournal, 2014;2014:342020.
    PMID: 25105158 DOI: 10.1155/2014/342020
    Bimetallic Cu-Ni/TiO2 photocatalysts were synthesized using wet impregnation (WI) method with TiO2 (Degussa-P25) as support and calcined at different temperatures (180, 200, and 300°C) for the photodegradation of DIPA under visible light. The photocatalysts were characterized using TGA, FESEM, UV-Vis diffuse reflectance spectroscopy, fourier transform infrared spectroscopy (FTIR) and temperature programmed reduction (TPR). The results from the photodegradation experiments revealed that the Cu-Ni/TiO2 photocatalysts exhibited much higher photocatalytic activities compared to bare TiO2. It was found that photocatalyst calcined at 200°C had the highest photocatalyst activities with highest chemical oxygen demand (COD) removal (86.82%). According to the structural and surface analysis, the enhanced photocatalytic activity could be attributed to its strong absorption into the visible region and high metal dispersion.
    Matched MeSH terms: Quaternary Ammonium Compounds/chemistry*
  17. Abd Ghani Aizat, Paiman, Bawon, Lee, Seng Hua, Ashaari Zaidon
    MyJurnal
    In this study, the effects of addition of ammonium and aluminium-based hardeners into
    urea formaldehyde resin (UF) on the physico-mechanical properties and formaldehyde
    emission of the rubberwood particleboard were investigated. Four types of hardeners,
    namely ammonium chloride (AC), ammonium sulphate (AS), aluminium chloride (AlC)
    and aluminium sulphate (AlS), were added into UF resin. The acidity, gelation time,
    viscosity and free formaldehyde content of the UF/hardener mixtures were determined.
    Particleboard made with the UF/hardener mixtures were tested for physico-mechanical
    properties and formaldehyde emission. The pH values of the resin after addition of
    aluminium-based hardeners were higher and resulted in higher viscosity and shorter
    gelation time. Consequently, despite lower formaldehyde emission was recorded, the
    physico-mechanical properties of the resulted particleboard were inferior compared to
    that of ammonium-based hardeners. The best quality particleboard in terms of mechanical,
    physical and formaldehyde emission were obtained from the particleboard made with AS,
    followed by AC.
    Matched MeSH terms: Ammonium Compounds
  18. Khan MF, Maulud KNA, Latif MT, Chung JX, Amil N, Alias A, et al.
    Sci Total Environ, 2018 Feb 01;613-614:1401-1416.
    PMID: 29898507 DOI: 10.1016/j.scitotenv.2017.08.025
    Air pollution can be detected through rainwater composition. In this study, long-term measurements (2000-2014) of wet deposition were made to evaluate the physicochemical interaction and the potential sources of pollution due to changes of land use. The rainwater samples were obtained from an urban site in Kuala Lumpur and a highland-rural site in the middle of Peninsular Malaysia. The compositions of rainwater were obtained from the Malaysian Meteorological Department. The results showed that the urban site experienced more acidity in rainwater (avg=277mm, range of 13.8 to 841mm; pH=4.37) than the rural background site (avg=245mm, range of 2.90 to 598mm; pH=4.97) due to higher anthropogenic input of acid precursors. The enrichment factor (EF) analysis showed that at both sites, SO42-, Ca2+ and K+ were less sensitive to seawater but were greatly influenced by soil dust. NH4+ and Ca2+ can neutralise a larger fraction of the available acid ions in the rainwater at the urban and rural background sites. However, acidifying potential was dominant at urban site compared to rural site. Source-receptor relationship via positive matrix factorisation (PMF 5.0) revealed four similar major sources at both sites with a large variation of the contribution proportions. For urban, the major sources influence on the rainwater chemistry were in the order of secondary nitrates and sulfates>ammonium-rich/agricultural farming>soil components>marine sea salt and biomass burning, while at the background site the order was secondary nitrates and sulfates>marine sea salt and biomass burning=soil components>ammonia-rich/agricultural farming. The long-term trend showed that anthropogenic activities and land use changes have greatly altered the rainwater compositions in the urban environment while the seasonality strongly affected the contribution of sources in the background environment.
    Matched MeSH terms: Ammonium Compounds
  19. Hii KS, Lim PT, Kon NF, Takata Y, Usup G, Leaw CP
    Harmful Algae, 2016 06;56:9-21.
    PMID: 28073499 DOI: 10.1016/j.hal.2016.04.005
    Saxitoxins (STXs) constitute a family of potent sodium channel blocking toxins, causative agents of paralytic shellfish poisoning (PSP), and are produced by several species of marine dinoflagellates and cyanobacteria. Two STX-core genes, sxtA and sxtG, have been well elucidated in Alexandrium but the expression of these genes under various nutritional modes in tropical species remains unclear. This study investigates the physiological responses of a tropical Pacific strain of Alexandrium minutum growing with nitrate or ammonium, and with various nitrogen to phosphorus (N:P) supply ratios. The transcriptional responses of the sxt genes were observed. Likewise, a putative sxtI encoding O-carbamoyltransferase (herein designated as AmsxtI) was recovered from the transcriptomic data, and its expression was investigated. The results revealed that the cellular toxin quota (Qt) was higher in P-depleted, nitrate-grown cultures. With cultures at similar N:P (<16), cells grown with excess ammonium showed a higher Qt than those grown with nitrate. sxtA1 was not expressed under any culture conditions, suggesting that this gene might not be involved in STX biosynthesis by this strain. Conversely, sxtA4 and sxtG showed positive correlations with Qt, and were up-regulated in P-depleted, nitrate-grown cultures and with excess ambient ammonium. On the other hand, AmsxtI was expressed only when induced by P-depletion, suggesting that this gene may play an important role in P-recycling metabolism, while simultaneously enhancing toxin production.
    Matched MeSH terms: Ammonium Compounds/metabolism
  20. Hamsan MH, Nofal MM, Aziz SB, Brza MA, Dannoun EMA, Murad AR, et al.
    Polymers (Basel), 2021 Apr 11;13(8).
    PMID: 33920346 DOI: 10.3390/polym13081233
    Chitosan (CS)-dextran (DN) biopolymer electrolytes doped with ammonium iodide (NH4I) and plasticized with glycerol (GL), then dispersed with Zn(II)-metal complex were fabricated for energy device application. The CS:DN:NH4I:Zn(II)-complex was plasticized with various amounts of GL and the impact of used metal complex and GL on the properties of the formed electrolyte were investigated.The electrochemical impedance spectroscopy (EIS) measurements have shown that the highest conductivity for the plasticized system was 3.44 × 10-4 S/cm. From the x-ray diffraction (XRD) measurements, the plasticized electrolyte with minimum degree of crystallinity has shown the maximum conductivity. The effect of (GL) plasticizer on the film morphology was studied using FESEM. It has been confirmed via transference number analysis (TNM) that the transport mechanism in the prepared electrolyte is predominantly ionic in nature with a high transference number of ion (ti)of 0.983. From a linear sweep voltammetry (LSV) study, the electrolyte was found to be electrochemically constant as the voltage sweeps linearly up to 1.25 V. The cyclic voltammetry (CV) curve covered most of the area of the current-potential plot with no redox peaks and the sweep rate was found to be affecting the capacitance. The electric double-layer capacitor (EDLC) has shown a great performance of specific capacitance (108.3 F/g), ESR(47.8 ohm), energy density (12.2 W/kg) and power density (1743.4 W/kg) for complete 100 cycles at a current density of 0.5 mA cm-2.
    Matched MeSH terms: Ammonium Compounds
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