Displaying publications 1 - 20 of 623 in total

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  1. Fulltext Genome Sequence of a Gram-Positive Diazotroph, Paenibacillus durus Type Strain ATCC 35681
    Halim MA, Rahman AY, Sim KS, Yam HC, Rahim AA, Ghazali AH, et al.
    Genome Announc, 2016;4(1).
    PMID: 26893411 DOI: 10.1128/genomeA.00005-16
    Here, we report the complete genome sequence of Paenibacillus durus type strain ATCC 35681, which can fix atmospheric nitrogen even in the presence of nitrate.
    Matched MeSH terms: Nitrogen; Nitrogen Oxides
  2. Accelerated organics degradation by peroxymonosulfate activated with biochar co-doped with nitrogen and sulfur
    Oh WD, Zaeni JRJ, Lisak G, Lin KA, Leong KH, Choong ZY
    Chemosphere, 2021 Aug;277:130313.
    PMID: 33780679 DOI: 10.1016/j.chemosphere.2021.130313
    Engineered biochar is increasingly regarded as a cost-effective and eco-friendly peroxymonosulfate (PMS) activator. Herein, biochar doped with nitrogen and sulfur moieties was prepared by pyrolysis of wood shavings and doping precursor. The doping precursor consists of either urea, thiourea or 1:1 w/w mixture of urea and thiourea (denoted as NSB-U, NSB-T and NSB-UT, respectively). The physicochemical properties of the NSBs were extensively characterized, revealing that they are of noncrystalline carbon with porous structure. The NSBs were employed as PMS activator to degrade organic pollutants particularly methylene blue (MB). It was found that NSB-UT exhibited higher MB removal rate with kapp = 0.202 min-1 due to its relatively high surface area and favorable intrinsic surface moieties (combination of graphitic N and thiophenic S). The effects of catalyst loading, PMS dosage and initial pH were evaluated. Positive enhancement of the MB removal rate can be obtained by carefully increasing the catalyst loading or PMS dosage. Meanwhile, the MB removal rate is greatly influenced by pH due to electrostatic interactions and pH dependent reactions. The NSB-UT can be reused for several cycles to some extent and its catalytic activity can be restored by thermal treatment. Based on the radical scavenger study and XPS analysis, the nonradical pathway facilitated by the graphitic N and thiophenic S active sites are revealed to be the dominant reaction pathway. Overall, the results of this study show that engineered biochar derived from locally available biowaste can be transformed into PMS activator for environmental applications.
    Matched MeSH terms: Nitrogen*
  3. Hierarchical ZIF-decorated nanoflower-covered 3-dimensional foam for enhanced catalytic reduction of nitrogen-containing contaminants
    Lin JY, Lee J, Oh WD, Kwon E, Tsai YC, Lisak G, et al.
    J Colloid Interface Sci, 2021 Nov 15;602:95-104.
    PMID: 34118608 DOI: 10.1016/j.jcis.2021.05.098
    Metal Organic Frameworks (MOFs) represent a promising class of metallic catalysts for reduction of nitrogen-containing contaminants (NCCs), such as 4-nitrophenol (4-NP). Nevertheless, most researches involving MOFs for 4-NP reduction employ noble metals in the form of fine powders, making these powdered noble metal-based MOFs impractical and inconvenient for realistic applications. Thus, it would be critical to develop non-noble-metal MOFs which can be incorporated into macroscale and porous supports for convenient applications. Herein, the present study proposes to develop a composite material which combines advantageous features of macroscale/porous supports, and nanoscale functionality of MOFs. In particular, copper foam (CF) is selected as a macroscale porous medium, which is covered by nanoflower-structured CoO to increase surfaces for growing a cobaltic MOF, ZIF-67. The resultant composite comprises of CF covered by CoO nanoflowers decorated with ZIF-67 to form a hierarchical 3D-structured catalyst, enabling this ZIF-67@Cu foam (ZIF@CF) a promising catalyst for reducing 4-NP, and other NCCs. Thus, ZIF@CF can readily reduce 4-NP to 4-AP with a significantly lower Ea of 20 kJ/mol than reported values. ZIF@CF could be reused over 10 cycles and remain highly effective for 4-NP reduction. ZIF@CF also efficiently reduces other NCCs, such as 2-nitrophenol, 3-nitrophenol, methylene blue, and methyl orange. ZIF@CF can be adopted as catalytic filters to enable filtration-type reduction of NCCs by passing NCC solutions through ZIF@CF to promptly and conveniently reduce NCCs. The versatile and advantageous catalytic activity of ZIF@CF validates that ZIF@CF is a promising and practical heterogeneous catalyst for reductive treatments of NCCs.
    Matched MeSH terms: Nitrogen*
  4. Physical profile and chemical composition of a novel fabricated Kaolina as alternative growing media in aquaponics
    Abdul Hamid SH, Lananan F, Kasan NA, Yasmin Sayid Abdullah SH, Endut A
    Chemosphere, 2022 Nov;307(Pt 4):136005.
    PMID: 35973500 DOI: 10.1016/j.chemosphere.2022.136005
    The physical profile and chemical composition of growing media are vital in evaluating fish waste filtration efficiency and plant growth performance in aquaponics. The present study reported and compared the physical and chemical evaluation of the novel fabricated Kaolina, gravel, and commercially used lightweight expanded clay aggregate (LECA) as growing medias in aquaponics. Field emission scanning electron microscopy with energy-dispersive X-ray spectroscopy (FESEM-EDX) was utilized to analyze the growing media's chemical composition and structural characterization. The resultant effect of these growing medias on water quality and the growth performance of Clarias gariepinus and Lactuca sativa were also reported. Kaolina exhibited an excellent physical profile (42.95 ± 1.39%) in water absorption capacity as compared to LECA (35.90 ± 1.28%) and gravel (1.97 ± 0.25%), showing a significant difference at p 
    Matched MeSH terms: Nitrogen Dioxide*
  5. Resource recovery from landfill leachate: An experimental investigation and perspectives
    Kurniawan TA, Singh D, Avtar R, Othman MHD, Hwang GH, Albadarin AB, et al.
    Chemosphere, 2021 Jul;274:129986.
    PMID: 33979934 DOI: 10.1016/j.chemosphere.2021.129986
    This work investigates the performances of coconut shell waste-based activated carbon (CSWAC) adsorption in batch studies for removal of ammoniacal nitrogen (NH3-N) and refractory pollutants (as indicated by decreasing COD concentration) from landfill leachate. To valorize unused resources, coconut shell, recovered and recycled from agricultural waste, was converted into activated carbon, which can be used for leachate treatment. The ozonation of the CSWAC was conducted to enhance its removal performance for target pollutants. The adsorption mechanisms of refractory pollutants by the adsorbent are proposed. Perspectives on nutrient recovery technologies from landfill leachate from the view-points of downstream processing are presented. Their removal efficiencies for both recalcitrant compounds and ammoniacal nitrogen were compared to those of other techniques reported in previous work. It is found that the ozonated CSWAC substantially removed COD (i.e. 76%) as well as NH3-N (i.e. 75%), as compared to the CSWAC without pretreatment (i.e. COD: 44%; NH3-N: 51%) with NH3-N and COD concentrations of 2750 and 8500 mg/L, respectively. This reveals the need of ozonation for the adsorbent to improve its performance for the removal of COD and NH3-N at optimized reactions: 30 g/L of CSWAC, pH 8, 200 rpm of shaking speed and 20 min of reaction time. Nevertheless, treatment of the leachate samples using the ozonated CSWAC alone was still unable to result in treated effluents that could meet the COD and NH3-N discharge standards below 200 and 5 mg/L, respectively, set by legislative requirements. This reveals that another treatment is necessary to be undertaken to comply with the requirement of their effluent limit.
    Matched MeSH terms: Nitrogen
  6. Nitrogen dynamics within an estuarine seagrass meadow under heavy anthropogenic influence
    Ashikin CN, Rozaimi M, Arina N, Fairoz M, Hidayah N
    Mar Pollut Bull, 2020 Jan;150:110628.
    PMID: 31740184 DOI: 10.1016/j.marpolbul.2019.110628
    Nitrogen is essential for seagrass productivity but excesses in nitrogen exposure contribute to declines in meadow health. This study reports baseline data of bulk nitrogen loadings and contents in surficial sediments and seagrass tissues to determine the extent of nitrogen inputs in meadows of Sungai Pulai estuary (Johor, Malaysia). The sediment contained relatively low nitrogen loadings (mean range of 91-94 g N m-2) with likely origins from land-based sources. At the meadow-level, Enhalus acoroides, Cymodocea serrulata and Thalassia hemprichii are the most important species as nitrogen sinks. The highest δ15N values of seagrass tissues were recorded for T. hemprichii (10.7 ± 0.4‰), which indicated an elevated capacity for internal recycling of nitrogen. The data demonstrates the provision of ecosystem services by the meadows in mitigating excess nitrogen imported into the estuary. Seagrasses health, however, needs to be at optimum levels for the effectiveness of the meadow as a nutrient sink.
    Matched MeSH terms: Nitrogen*; Nitrogen Cycle*
  7. Sources and cycling of nitrogen revealed by stable isotopes in a highly populated large temperate coastal embayment
    Wong WW, Cartwright I, Poh SC, Cook P
    Sci Total Environ, 2022 Feb 01;806(Pt 1):150408.
    PMID: 34571224 DOI: 10.1016/j.scitotenv.2021.150408
    The identification of nitrogen sources and cycling processes is critical to the management of nitrogen pollution. Here, we used both stable (δ15N-NO3-, δ18O-NO3-, δ15N-NH4+) and radiogenic (222Rn) isotopes together with nitrogen concentrations to evaluate the relative importance of point (i.e. sewage) and diffuse sources (i.e. agricultural-derived NO3- from groundwater, drains and creeks) in driving nitrogen dynamic in a shallow coastal embayment, Port Phillip Bay (PPB) in Victoria, Australia. This study is an exemplar of nitrogen-limited coastal systems around the world where nitrogen contamination is prevalent and where constraining it may be challenging. In addition to surrounding land use, we found that the distributions of NO3- and NH4+ in the bay were closely linked to the presence of drift algae. Highest NO3- and NH4+ concentrations were 315 μmol L-1 and 2140 μmol L-1, respectively. Based on the isotopic signatures of NO3- (δ15N: 0.17 to 21‰; δ18O: 3 to 26‰) and NH4+ (δ15N: 30 to 39‰) in PPB, the high nitrogen concentrations were attributed to three major sources which varied between winter and summer; (1) nitrified sewage effluent and drift algae derived NH4+ mainly during winter, (2) NO3- mixture from atmospheric deposition, drains and creeks predominantly observed during summer and (3) groundwater and sewage derived NO3- during both surveys. The isotopic composition of NO3- also suggested the removal of agriculture-derived NO3- through denitrification was prevalent during transport. This study highlights the role of terrestrial-coastal interactions on nitrogen dynamics and illustrates the importance of submarine groundwater discharge as a prominent pathway of diffuse NO3- inputs. Quantifying the relative contributions of multiple NO3- input pathways, however, require more extensive efforts and is an important avenue for future research.
    Matched MeSH terms: Nitrogen/analysis; Nitrogen Isotopes/analysis
  8. Effects of drift algae accumulation and nitrate loading on nitrogen cycling in a eutrophic coastal sediment
    Wong WW, Greening C, Shelley G, Lappan R, Leung PM, Kessler A, et al.
    Sci Total Environ, 2021 Oct 10;790:147749.
    PMID: 34091344 DOI: 10.1016/j.scitotenv.2021.147749
    The permeable (sandy) sediments that dominate the world's coastlines and continental shelves are highly exposed to nitrogen pollution, predominantly due to increased urbanisation and inefficient agricultural practices. This leads to eutrophication, accumulation of drift algae and changes in the reactions of nitrogen, including the potential to produce the greenhouse gas nitrous oxide (N2O). Nitrogen pollution in coastal systems has been identified as a global environmental issue, but it remains unclear how this nitrogen is stored and processed by permeable sediments. We investigated the interaction of drift algae biomass and nitrate (NO3-) exposure on nitrogen cycling in permeable sediments that were impacted by high nitrogen loading. We treated permeable sediments with increasing quantities of added macroalgal material and NO3- and measured denitrification, dissimilatory NO3- reduction to ammonium (DNRA), anammox, and nitrous oxide (N2O) production, alongside abundance of marker genes for nitrogen cycling and microbial community composition by metagenomics. We found that the presence of macroalgae dramatically increased DNRA and N2O production in sediments without NO3- treatment, concomitant with increased abundance of nitrate-ammonifying bacteria (e.g. Shewanella and Arcobacter). Following NO3- treatment, DNRA and N2O production dropped substantially while denitrification increased. This is explained by a shift in the relative abundance of nitrogen-cycling microorganisms under different NO3- exposure scenarios. Decreases in both DNRA and N2O production coincided with increases in the marker genes for each step of the denitrification pathway (narG, nirS, norB, nosZ) and a decrease in the DNRA marker gene nrfA. These shifts were accompanied by an increased abundance of facultative denitrifying lineages (e.g. Pseudomonas and Marinobacter) with NO3- treatment. These findings identify new feedbacks between eutrophication and greenhouse gas emissions, and in turn have potential to inform biogeochemical models and mitigation strategies for marine eutrophication.
    Matched MeSH terms: Nitrogen; Nitrogen Cycle
  9. Effect of air flow rate and C/N ratio on biological nitrogen removal through the CANON process treating reject water
    Mousavi SA, Mehralian M, Khashij M, Ibrahim S
    Environ Technol, 2018 Nov;39(22):2891-2899.
    PMID: 28820045 DOI: 10.1080/09593330.2017.1369578
    The CANON process is a promising method for nitrogen removal in wastewaters with low organic carbon content like reject water. This study investigated the effect of important factors for optimization of the CANON process through inhibition of nitrite-oxidizing bacteria (NOB). In the acclimation period, complete ammonium removal and 43.3% total N removal were obtained at hydraulic retention time of 12 h, temperature of 30°C ± 0.5°C and DO equal to 7-9 mg/L. The effects of air flow rate (AFR) (representative of DO), SRT and C/N were evaluated. Air flow rate was the most important factor for controlling the process, but the effect of SRT was negligible. When AFR was increased from 100 to 500 mL/min, both ammonium removal efficiency (33-43% to 81-83%) and nitrite accumulation (nitritation, 40 mgN/L to 100-120 mgN/L) were increased, but with increasing AFR to 1000 mL/min only ammonium removal efficiency was increased and because of better condition (high DO) for NOBs, nitritation was decreased. C/N had an effect like AFR of 1000 and only increased ammonium removal efficiency and total N removal. With increasing AFR and C/N, both OUR and AUR were increased, but SVI was decreased.
    Matched MeSH terms: Nitrogen*
  10. Attempts to minimize nitrogen oxide emission from diesel engine by using antioxidant-treated diesel-biodiesel blend
    Rashedul HK, Kalam MA, Masjuki HH, Teoh YH, How HG, Monirul IM, et al.
    Environ Sci Pollut Res Int, 2017 Apr;24(10):9305-9313.
    PMID: 28233198 DOI: 10.1007/s11356-017-8573-9
    The study represents a comprehensive analysis of engine exhaust emission variation from a compression ignition (CI) diesel engine fueled with diesel-biodiesel blends. Biodiesel used in this investigation was produced through transesterification procedure from Moringa oleifera oil. A single cylinder, four-stroke, water-cooled, naturally aspirated diesel engine was used for this purpose. The pollutants from the exhaust of the engine that are monitored in this study are nitrogen oxide (NO), carbon monoxide (CO), hydrocarbon (HC), and smoke opacity. Engine combustion and performance parameters are also measured together with exhaust emission data. Some researchers have reported that the reason for higher NO emission of biodiesel is higher prompt NO formation. The use of antioxidant-treated biodiesel in a diesel engine is a promising approach because antioxidants reduce the formation of free radicals, which are responsible for the formation of prompt NO during combustion. Two different antioxidant additives namely 2,6-di-tert-butyl-4-methylphenol (BHT) and 2,2'-methylenebis(4-methyl-6-tert-butylphenol) (MBEBP) were individually dissolved at a concentration of 1% by volume in MB30 (30% moringa biodiesel with 70% diesel) fuel blend to investigate and compare NO as well as other emissions. The result shows that both antioxidants reduced NO emission significantly; however, HC, CO, and smoke were found slightly higher compared to pure biodiesel blends, but not more than the baseline fuel diesel. The result also shows that both antioxidants were quite effective in reducing peak heat release rate (HRR) and brake-specific fuel consumption (BSFC) as well as improving brake thermal efficiency (BTE) and oxidation stability. Based on this study, antioxidant-treated M. oleifera biodiesel blend (MB30) can be used as a very promising alternative source of fuel in diesel engine without any modifications.
    Matched MeSH terms: Nitrogen Oxides*
  11. Risk assessment of non-point source pollution based on landscape pattern in the Hanjiang River basin, China
    Liu YW, Li JK, Xia J, Hao GR, Teo FY
    Environ Sci Pollut Res Int, 2021 Dec;28(45):64322-64336.
    PMID: 34304355 DOI: 10.1007/s11356-021-15603-w
    Non-point source (NPS) pollution has become a vital contaminant source affecting the water environment because of its wide distribution, hydrodynamic complexity, and difficulty in prevention and control. In this study, the identification and evaluation of NPS pollution risk based on landscape pattern were carried out in the Hanjiang River basin above Ankang hydrological section, Shaanxi province, China. Landscape distribution information was obtained through land use data, analyzing the contribution of "source-sink" landscape to NPS pollution through the location-weighted landscape contrast index. Using the NPS pollution risk index to identify and evaluate the regional NPS pollution risk considering the slope, cost distance, soil erosion, and precipitation erosion affect migration of pollutants. The results showed that (i) the pollution risk was generally high in the whole watershed, and the sub-watersheds dominated by "source" landscapes account for 74.61% of the whole basin; (ii) the high-risk areas were distributed in the central, eastern, and western regions of the river basin; the extremely high-risk areas accounted for 12.7% of the whole watershed; and the southern and northern regions were dominated by forestland and grassland with little pollution risk; (iii) "source" landscapes were mostly distributed in areas close to the river course, which had a great impact on environment, and the landscape pattern units near the water body needed to be further adjusted to reduce the influence of NPS pollution.
    Matched MeSH terms: Nitrogen/analysis
  12. Fulltext Ecofriendly adsorption and sensitive detection of Hg (II) by biomass-derived nitrogen-doped carbon dots: process modelling using central composite design
    Issa MA, Zentou H, Jabbar ZH, Abidin ZZ, Harun H, Halim NAA, et al.
    Environ Sci Pollut Res Int, 2022 Dec;29(57):86859-86872.
    PMID: 35802332 DOI: 10.1007/s11356-022-21844-0
    In this study, luminescent bio-adsorbent nitrogen-doped carbon dots (N-CDs) was produced and applied for the removal and detection of Hg (II) from aqueous media. N-CDs were synthesized from oil palm empty fruit bunch carboxymethylcellulose (CMC) and urea. According to several analytical techniques used, the obtained N-CDs display graphitic core with an average size of 4.2 nm, are enriched with active sites, stable over a wide range of pH and have great resistance to photobleaching. The N-CDs have bright blue emission with an improved quantum yield (QY) of up to 35.5%. The effect of the variables including pH, adsorbent mass, initial concentration and incubation time on the removal of Hg (II) was investigated using central composite design. The statistical results confirmed that the adsorption process could reach equilibrium within 30 min. The reduced cubic model (R2 = 0.9989) revealed a good correlation between the observed values and predicted data. The optimal variables were pH of 7, dose of 0.1 g, initial concentration of 100 mg/L and duration of 30 min. Under these conditions, adsorption efficiency of 84.6% was obtained. The adsorption kinetic data could be well expressed by pseudo-second-order kinetic and Langmuir isotherm models. The optimal adsorption capacity was 116.3 mg g-1. Furthermore, the adsorbent has a good selectivity towards Hg (II) with a detection limit of 0.01 μM due to the special interaction between Hg (II) and carboxyl/amino groups on the edge of N-CDs. This work provided an alternative direction for constructing low-cost adsorbents with effective sorption and sensing of Hg (II).
    Matched MeSH terms: Nitrogen/chemistry
  13. The combined action of biochar and nitrogen-fixing bacteria on microbial and enzymatic activities of soil N cycling
    Gou Z, Zheng H, He Z, Su Y, Chen S, Chen H, et al.
    Environ Pollut, 2023 Jan 15;317:120790.
    PMID: 36460190 DOI: 10.1016/j.envpol.2022.120790
    This study aims to investigate the positive effects of the combined use of Enterobacter cloacae and biochar on improving nitrogen (N) utilization. The greenhouse pots experimental results showed the synergy of biochar and E. cloacae increased soil total N content and plant N uptake by 33.54% and 15.1%, respectively. Soil nitrogenase (NIT) activity increased by 253.02%. Ammonia monooxygenase (AMO) and nitrate reductase (NR) activity associated with nitrification and denitrification decreased by 10.94% and 29.09%, respectively. The relative abundance of N fixing microorganisms like Burkholderia and Bradyrhizobium significantly increased. Sphingomonas and Ottowia, two bacteria involved in the nitrification and denitrification processes, were found to be in lower numbers. The E. cloacae's ability to fix N2 and promote the growth of plants allow the retention of N in soil and make more N available for plant development. Biochar served as a reservoir of N for plants by adsorbing N from the soil and providing a shelter for E. cloacae. Thus, biochar and E. cloacae form a synergy for the management of agricultural N and the mitigation of negative impacts of pollution caused by excessive use of N fertilizer.
    Matched MeSH terms: Nitrogen; Nitrogen-Fixing Bacteria*
  14. Glutathione conjugation of nitrogen mustards: In vitro study
    Hamzah N, Kjellberg M, Vanninen P
    Rapid Commun Mass Spectrom, 2023 May 15;37(9):e9495.
    PMID: 36799074 DOI: 10.1002/rcm.9495
    RATIONALE: This paper describes an in vitro study designed to identify metabolic biomarkers resulting from the conjugation of nitrogen mustards (NMs) with glutathione (GSH). The method developed is essential in providing evidence in the event of NM exposure in biomedical samples.

    METHODS: The mass spectral characterization of the proposed NMs-GSH conjugates was performed with liquid chromatography high-resolution tandem mass spectrometry (LC-HRMS/MS). The final reaction mixtures were analysed in positive electrospray ionisation (ESI) at different incubation times.

    RESULTS: This study identified three types of conjugates in addition to ethanolamines, the hydrolysis products of NMs. Monoglutathionyl, diglutathionyl and phosphorylated conjugates were produced for each of the NMs, bis(2-chloroethyl)ethylamine (HN1), bis(2-chloroethyl)methylamine (HN2) and tris(2-chloroethyl)amine (HN3). The monoglutathionyl conjugates consisted of HN1-GSH, HN2-GSH and HN3-GSH. The spontaneous and primary conjugates of diglutathionyl were HN1-GSH2, HN2-GSH2 and HN3-GSH2. These included phosphorylated conjugates, namely HN1-GSH-PO4 , HN2-GSH-PO4 and HN3-GSH-PO4 , as might have formed due to hydrolysis in phosphate buffer.

    CONCLUSIONS: The mass spectral data of all conjugates formed in the presence of all NMs and GSH are reported in this study. These GSH metabolites can be used to confirm NMs toxicity in biological samples such as urine.

    Matched MeSH terms: Nitrogen; Nitrogen Mustard Compounds*
  15. Inoculation of Bacillus sphaericus UPMB-10 to young oil palm and measurement of its uptake of fixed nitrogen using the ¹⁵N isotope dilution technique
    Zakry FA, Shamsuddin ZH, Abdul Rahim K, Zawawi Zakaria Z, Abdul Rahim A
    Microbes Environ, 2012;27(3):257-62.
    PMID: 22446306
    There are increasing applications of diazotrophic rhizobacteria in the sustainable agriculture system. A field experiment on young immature oil palm was conducted to quantify the uptake of N derived from N₂ fixation by the diazotroph Bacillus sphaericus strain UPMB-10, using the ¹⁵N isotope dilution method. Eight months after ¹⁵N application, young immature oil palms that received 67% of standard N fertilizer application together with B. sphaericus inoculation had significantly lower ¹⁵N enrichment than uninoculated palms that received similar N fertilizers. The dilution of labeled N served as a marker for the occurrence of biological N₂ fixation. The proportion of N uptake that was derived from the atmosphere was estimated as 63% on the whole plant basis. The inoculation process increased the N and dry matter yields of the palm leaflets and rachis significantly. Field planting of young, immature oil palm in soil inoculated with B. sphaericus UPMB-10 might mitigate inorganic fertilizer-N application through supplementation by biological nitrogen fixation. This could be a new and important source of nitrogen biofertilizer in the early phase of oil palm cultivation in the field.
    Matched MeSH terms: Nitrogen/metabolism*; Nitrogen Fixation
  16. Pembangunan sel fuel mikrob untuk rawatan air sisa kilang sawit
    Lim SS, Jamaliah Md. Jahim, Siti Norhana Shari, Manal Ismail, Wan Ramli Wan Daud
    Sains Malaysiana, 2012;41:1253-1261.
    Sel fuel mikrob (SFM) merupakan peranti yang menggunakan bakteria sebagai biomangkin untuk mengoksidakan bahan organik dan bukan organik bagi menjanakan arus elektrik. Tujuan utama kajian ini ialah menguji kebolehan SFM skala makmal dengan menggunakan enapcemar yang mengandungi kultur campuran yang hidup dalam air sisa buangan kilang pemprosesan sawit (POME). Kajian ini juga bertujuan membina reka bentuk SFM yang sesuai dan mengkaji keaktifan kultur campuran yang boleh menghasilkan kuasa elektrik. POME telah digunakan dalam bentuk yang dicairkan dengan kandungan COD bersamaan dengan 3750 mg-COD L-1. Prestasi penghasilan kuasa elektrik dan kecekapan rawatan yang dinilai daripada segi penyingkiran COD, nitrogen dan jumlah karbohidrat dalam SFM dwi-ruang telah dicatat dan dianalisis setiap hari selama 15 hari. Hasil padanan uji kaji dan model kekutuban adalah memuaskan dan telah menjelaskan ketumpatan kuasa elektrik yang dapat dihasilkan pada setiap hari. Ketumpatan kuasa didapati meningkat dari hari pertama 1.607 mW m-2 (3.816 mA m-2) ke nilai maksimum pada hari ketiga 1.979 mW m-2 (4.780 mA m-2) dan mula turun sehingga minimum pada hari ketujuh 1.311 mW m-2 (3.346 mA m-2). Peringkat rawatan air sisa kilang sawit oleh SFM boleh dibahagikan kepada tiga tahap yang berbeza. Kecekapan rawatan yang rendah walaupun ketumpatan kuasa meningkat pada tahap pertama, manakala pada tahap kedua kecekapan rawatan lebih tinggi dan akhirnya pada tahap ketiga penghasilan kuasa SFM mula turun. Kecekapan rawatan paling tinggi berlaku pada tahap ketiga semasa penghasilan kuasa elektrik yang terhasil agak malar. Kecekapan rawatan yang dinilaikan dalam bentuk penyingkiran COD, penggunaan nitrogen dan karbohidrat paling tinggi berlaku pada hari ke-15 dengan nilai masing-masing adalah 54.9, 100 dan 98.9%. Hubungan penghasilan kuasa elektrik dan kecekapan rawatan telah berjaya dimodelkan dalam persamaan linear matematik berdasarkan kepada tahap-tahap penghasilan kuasa elektrik ini.
    Matched MeSH terms: Nitrogen
  17. Sintesis dan pencirian kobalt sulfida menggunakan misel ester sukrosa dan kegunaan sebagai penjerap pewarna
    Huang N, Radiman S, Chia C, Lim H, Khiew P, Chiu W, et al.
    Sains Malaysiana, 2009;38.
    Kobalt sulfida telah dihasilkan dengan kaedah pemendakan kimia di dalam kehadiran 0.1% ester sukrosa S1670s. Corak pembelauan sinar-x (XRD) menunjukkan kobalt sulfida yang dihasilkan mempunyai sifat amofos dan analisis sinar-x (EDX) menunjukkan kobalt sulfida yang terbentuk mempunyai nisbah atom Co: S dalam 1:1.08 iaitu CoS. CoS yang terbentuk mempunyai struktur liang bersaiz nano (~10 nm) apabila diperhatikan di bawah elektron mikroskop transmisi (TEM) dan disahkan oleh ujian penjerapan gas nitrogen (BET). Pembentukan struktur liang adalah disebabkan oleh struktur misel ester sukrosa yang mempunyai saiz misel dalam lingkungan 10 nm. CoS yang dihasilkan diuji keupayaan penjerapan dengan metilena biru sebagai sampel pewarna. Didapati keupayaan penjerapan optimum CoS ialah 110 mg/g dan pH yang paling sesuai untuk penjerapan berlaku adalah lebih daripada 6.
    Matched MeSH terms: Nitrogen
  18. Point-Defect Engineering: Leveraging Imperfections in Graphitic Carbon Nitride (g-C3 N4 ) Photocatalysts toward Artificial Photosynthesis
    Yu X, Ng SF, Putri LK, Tan LL, Mohamed AR, Ong WJ
    Small, 2021 12;17(48):e2006851.
    PMID: 33909946 DOI: 10.1002/smll.202006851
    Graphitic carbon nitride (g-C3 N4 ) is a kind of ideal metal-free photocatalysts for artificial photosynthesis. At present, pristine g-C3 N4 suffers from small specific surface area, poor light absorption at longer wavelengths, low charge migration rate, and a high recombination rate of photogenerated electron-hole pairs, which significantly limit its performance. Among a myriad of modification strategies, point-defect engineering, namely tunable vacancies and dopant introduction, is capable of harnessing the superb structural, textural, optical, and electronic properties of g-C3 N4 to acquire an ameliorated photocatalytic activity. In view of the burgeoning development in this pacey field, a timely review on the state-of-the-art advancement of point-defect engineering of g-C3 N4 is of vital significance to advance the solar energy conversion. Particularly, insights into the intriguing roles of point defects, the synthesis, characterizations, and the systematic control of point defects, as well as the versatile application of defective g-C3 N4 -based nanomaterials toward photocatalytic water splitting, carbon dioxide reduction and nitrogen fixation will be presented in detail. Lastly, this review will conclude with a balanced perspective on the technical and scientific hindrances and future prospects. Overall, it is envisioned that this review will open a new frontier to uncover novel functionalities of defective g-C3 N4 -based nanostructures in energy catalysis.
    Matched MeSH terms: Nitrogen Compounds
  19. Capture of mammal excreta by Nepenthes is an effective heterotrophic nutrition strategy
    Cross AT, van der Ent A, Wickmann M, Skates LM, Sumail S, Gebauer G, et al.
    Ann Bot, 2022 Dec 31;130(7):927-938.
    PMID: 36306274 DOI: 10.1093/aob/mcac134
    BACKGROUND AND AIMS: While isotopic enrichment of nitrogen (15N) and carbon (13C) is often used to determine whether carnivorous plant species capture and assimilate nutrients from supplemental sources such as invertebrate prey or mammal excreta (heterotrophic nutrition), little is known about how successful the different strategies deployed by carnivorous plants are at obtaining supplemental nutrition. The collection of mammalian faeces by Nepenthes (tropical pitcher plants) is the result of a highly specialized biological mutualism that results in heterotrophic nitrogen gain; however, it remains unknown how effective this strategy is in comparison to Nepenthes species not known to collect mammalian faeces.

    METHODS: We examined how isotopic enrichment varied in the diverse genus Nepenthes, among species producing pitchers for invertebrate capture and species exhibiting mutualisms for the collection of mammal excreta. Enrichment factors were calculated from δ15N and δ13C values from eight Nepenthes species and naturally occurring hybrids along with co-occurring reference (non-carnivorous) plants from three mountain massifs in Borneo: Mount Kinabalu, Mount Tambuyukon and Mount Trus Madi.

    RESULTS: All Nepenthes examined, except N. edwardsiana, were significantly enriched in 15N compared to co-occurring non-carnivorous plants, and 15N enrichment was more than two-fold higher in species with adaptations for the collection of mammal excreta compared with other Nepenthes.

    CONCLUSIONS: The collection of mammal faeces clearly represents a highly effective strategy for heterotrophic nitrogen gain in Nepenthes. Species with adaptations for capturing mammal excreta occur exclusively at high elevation (i.e. are typically summit-occurring) where previous studies suggest invertebrate prey are less abundant and less frequently captured. As such, we propose this strategy may maximize nutritional return by specializing towards ensuring the collection and retention of few but higher-value N sources in environments where invertebrate prey may be scarce.

    Matched MeSH terms: Nitrogen
  20. Exploring use of a commercial passive sampler in a closed static chamber to measure ammonia volatilization
    Sabrina J, Nurulhuda K, Amin AM, Sulaiman MF, Man HC
    Environ Pollut, 2022 Dec 15;315:120282.
    PMID: 36174812 DOI: 10.1016/j.envpol.2022.120282
    Studies have indicated that up to 47% of total N fertilizer applied in flooded rice fields may be lost to the atmosphere through NH3 volatilization. The volatilized NH3 represents monetary loss and contributes to increase in formation of PM2.5 in the atmosphere, eutrophication in surface water, and degrades water and soil quality. The NH3 is also a precursor to N2O formation. Thus, it is important to monitor NH3 volatilization from fertilized and flooded rice fields. Commercially available samplers offer ease of transportation and installation, and thus, may be considered as NH3 absorbents for the static chamber method. Hence, the objective of this study is to investigate the use of a commercially available NH3 sampler/absorbent (i.e., Ogawa® passive sampler) for implementation in a static chamber. In this study, forty closed static chambers were used to study two factors (i.e., trapping methods, exposure duration) arranged in a Randomized Complete Block Design. The three trapping methods are standard boric acid solution, Ogawa® passive sampler with acid-coated pads and exposed coated pads without casing. The exposure durations are 1 and 4 h. Results suggest that different levels of absorbed NH3 was obtained for each of the trapping methods. Highest level of NH3 was trapped by the standard boric acid solution, followed by the exposed acid-coated pads without casing, and finally acid-coated pads with protective casing, given the same exposure duration. The differences in absorbed NH3 under same conditions does not warrant direct comparison across the different trapping methods. Any three trapping methods can be used for conducting studies to compare multi-treatments using the static chamber method, provided the same trapping method is applied for all chambers.
    Matched MeSH terms: Nitrogen
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