Displaying publications 121 - 140 of 515 in total

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  1. A case study on the source apportionment of indoor air quality at a kindergarten in eastern Peninsular Malaysia using cluster analysis
    Sidek SS, Yatim SRM, Abdullah S, Shafie FA, Ishak AR, Dom NC, et al.
    Med J Malaysia, 2024 Mar;79(Suppl 1):104-109.
    PMID: 38555893
    BACKGROUND: Indoor air quality is an important concern for kindergartener because young children are more vulnerable to the effects of poor air quality. Poor indoor air quality can cause respiratory problems and other health issues, which can negatively affect a child's ability to learn and grow. Aim of this study is to determine the trend and status of indoor air pollutants in study areas by using descriptive statistics and cluster analysis.

    MATERIALS AND METHODS: Air temperature (T), relative humidity (RH), air movement (AM), carbon dioxide (CO2), formaldehyde (HCHO), and particulate matter (PM) are the monitored parameters. Monitoring was carried out in the kindergarten for three consecutive days starting from 8.00am to 12.00pm.

    RESULTS: Indoor carbon dioxide readings were higher at 0800 when parents drove to kindergarten to drop off their children without turning off the engine. In addition to this, the PM10 reading at 1000 was high but still within the standard range according to ICOP-IAQ 2010.

    CONCLUSION: The findings highlight the importance of indoor air quality improvement measures for kindergarten buildings which can be used to improve indoor air quality in kindergarten environments.

    Matched MeSH terms: Carbon Dioxide/analysis
  2. How marine tourism promote financial development in sustainable economy: new evidences from South Asia and implications to future tourism students
    Li L, Wu B, Patwary AK
    Environ Sci Pollut Res Int, 2022 Jan;29(1):1155-1172.
    PMID: 34350576 DOI: 10.1007/s11356-021-15709-1
    The ocean economy and marine tourism policies are global economic concerns being looked at from a deeply holistic viewpoint. For South Asian countries, the ocean economy and marine tourism have successive socio-economic importance. The quantification of the ocean economy and marine tourism also poses some major challenges, and these challenges pose limitations for policymaking by the government and other relevant agencies. The study has used the newly developed hidden panel cointegration test, and the nonlinear panel autoregressive distributed lag (NPARDL) model for a relationship between economic growth and tourism is assessed. This study offers consistent and reliable results of cointegration by incorporating the findings of four approaches to cointegration. The empirical results illustrate the asymmetric relationship between ocean and marine tourism and economic growth. The findings showed that 1% increase in long-term tourism economic growth is adjusted by 2.95% annually. This research paper aims to provide a policy related to South Asia's economic activities and ocean and marine tourism economic significance. Protecting local marine protected areas (MPAs) will improve the economic benefits of the ocean and the marine economy. The policy suggests that there should be a law ensuring that marine tourism is of high quality and environment friendly. This paper provides a guideline for further research with a strong emphasis on ocean- and marine-related economic development and tourism.
    Matched MeSH terms: Carbon Dioxide/analysis
  3. Dynamic linkages between non-renewable energy, renewable energy and economic growth through nonlinear ARDL approach: evidence from Malaysia
    Afroz R, Muhibbullah M
    Environ Sci Pollut Res Int, 2022 Jul;29(32):48795-48811.
    PMID: 35201582 DOI: 10.1007/s11356-022-19346-0
    The purpose of this paper is to investigate the links between renewable energy (RE), non-renewable energy (NRE), capital, labour and economic growth, using the nonlinear autoregressive distributive lag (NARDL) model in Malaysia for the period of 1980-2018. The results of NARDL confirm the asymmetric effect of RE and NRE consumption on the economic growth in the long run as well as the short run in Malaysia. The findings also show that in the long and short run, positive shocks of NRE are greater than the positive shocks of RE. It indicates that Malaysia's economic growth is highly dependent on NRE which is not a good indication as NRE consumption increases carbon dioxide (CO2) emission in the country. Moreover, the empirical results of this study demonstrated that RE consumption reduction accelerates economic growth, whereas NRE consumption reduction decreases economic growth. It can have claimed that in Malaysia, RE is still more expensive than NRE. In conclusion, this study offered a variety of measures to develop RE to reduce the dependency on NRE consumption.
    Matched MeSH terms: Carbon Dioxide/analysis
  4. Fulltext The impact of fiscal decentralization, green energy, and economic policy uncertainty on sustainable environment: a new perspective from ecological footprint in five OECD countries
    Zahra S, Badeeb RA
    Environ Sci Pollut Res Int, 2022 Aug;29(36):54698-54717.
    PMID: 35305216 DOI: 10.1007/s11356-022-19669-y
    The paper explores the short-run and long-run asymmetric impact of fiscal decentralization, green energy, and economic policy uncertainty on environmental sustainability proxied by ecological footprint. Using the Nonlinear Autoregressive Distributed lag (NARDL) approach in selected five OECD countries, we find that ecological footprint responds to positive and negative fiscal decentralization asymmetrically in the long run and short run. However, the nature of the response varies significantly across countries. The result also suggests that green energy is a major factor in reducing the ecological footprint in all countries except Canada. Finally, economic policy uncertainty plays a negative and significant role in the ecological footprint in the UK, USA, and Germany while insignificant in Australia and Canada. Implications for effective environmental policies are discussed.
    Matched MeSH terms: Carbon Dioxide*
  5. Modelling the role of energy price movements toward economic stability in Malaysia: new evidence from wavelet-based analysis
    Afshan S, Cheong CWH, Sharif A
    Environ Sci Pollut Res Int, 2023 Aug;30(38):88861-88875.
    PMID: 37440132 DOI: 10.1007/s11356-023-28660-0
    Energy is one of the prime factors in influencing the sustainable development of a country. Different energy sources play important roles in driving the income growth of different economic sectors such as industrial, agricultural, and services. Fossil fuels, however, have come under strong criticism for actively accelerating climate change. As such, it is imperative to investigate the contributions of various energy sources toward sustainable growth. With Malaysia as the test-bed, the present study analyzes the impact of energy prices on economic stability using the novel wavelet-based analysis. Specifically, the study analyzed the impact of crude oil, natural gas, and gasoline prices on the economic (brown) and green growth from 1995 to 2020. The results show that in continuous wavelet transform, the cone of influence of all five factors exhibits strong short-run variance and fluctuations from 2005 to 2013. However, the intensity of brown growth is more influential than green growth. Similarly, in wavelet coherence graphs, the downward right arrows indicate positively significant associations between crude oil prices, natural gas prices, and gasoline prices with brown and green growth. Additionally, wavelet-based Granger causality reveals a bidirectional causal relationship between all variables. The results thus strongly suggest that energy prices predominantly affect the economic (brown) and green growth progression of the Malaysian economy. The study concludes with some suggested implications to augment the country's sustainable growth.
    Matched MeSH terms: Carbon Dioxide/analysis
  6. The step towards environmental mitigation in Pakistan: do transportation services, urbanization, and financial development matter?
    Godil DI, Ahmad P, Ashraf MS, Sarwat S, Sharif A, Shabib-Ul-Hasan S, et al.
    Environ Sci Pollut Res Int, 2021 May;28(17):21486-21498.
    PMID: 33415625 DOI: 10.1007/s11356-020-11839-0
    This study is a scholarly effort to broaden the existing literature on the impact of transportation services, urbanization, and financial development on ecological footprints in Pakistan. Data used in this study covers the period of 39 years from 1980 to 2018. This study adopted the QARDL model to tackle the non-linear association of variables and test their long-run stability across the different quantiles. The findings of this study indicated a significant negative association of transportation services and financial development with ecological footprints in Pakistan at almost all quantiles whereas, the urban population was found to be positively associated with the ecological footprint in Pakistan. Results also justify the existence of the EKC hypothesis in the scenario of Pakistan. Policymakers are advised to frame strategies for investors to invest more in eco-friendly projects to curtail the ecological footprints in Pakistan. Minimizing the dependency of the transportation sector on fossil fuel, and increased use of energy-efficient appliances in the urban population would be beneficial to control the negative influence on ecological footprints in Pakistan.
    Matched MeSH terms: Carbon Dioxide/analysis
  7. Multi-objectives optimization on microwave-assisted-biological-based biogas upgrading and bio-succinic acid production
    Adnan AI, Ong MY, Mohamed H, Chia SR, Milano J, Nomanbhay S
    Bioresour Technol, 2024 Aug;406:131028.
    PMID: 38914237 DOI: 10.1016/j.biortech.2024.131028
    This study represents the first investigation of bio-succinic acid (bio-SA) production with methane enrichment using carbon-dioxide-fixating bacteria in the co-culture of ragi tapai and macroalgae, Chaetomorpha. Microwave irradiation has also been introduced to enhance the biochemical processes as it could provide rapid and selective heating of substrates. In this research, microwave irradiation was applied on ragi tapai as a pre-treatment process. Factors such as microwave irradiation dose on ragi tapai, Chaetomorpha ratio in the co-culture, and pH value were studied. Optimal conditions were identified using Design-Expert software, resulting in optimal experimental biomethane and bio-SA production of 85.7 % and 0.65 g/L, respectively, at a microwave dose of 1.45 W/g, Chaetomorpha ratio of 0.9 and pH value of 7.8. The study provides valuable insights into microwave control for promoting simultaneous methane enrichment and bio-SA production, potentially reducing costs associated with CO2 capture and storage and biogas upgrading.
    Matched MeSH terms: Carbon Dioxide/metabolism
  8. Carbon footprints and health security: A comparative assessment of the Sustainable Development Goals 3 and 13 in East Asian countries
    Sun M, Han S, Liu Y
    Afr J Reprod Health, 2024 Aug 31;28(8):99 107.
    PMID: 39225496 DOI: 10.29063/ajrh2024/v28i8.10
    In East Asia, where several countries are among the top emitters of carbon dioxide globally, the need to address the dual challenges of reducing carbon footprints and ensuring health security is paramount. Against this backdrop, this study used a descriptive analysis to provide a comparative assessment of the carbon footprints and the level of health security in East Asia using secondary data, sourced from the World Development Indicators. The findings from the study show that it is only North Korea that its average carbon footprint of every person is less than 2.3 tons. However, China, Japan, Mongolia and South Korea are currently lagging behind in meeting the SDG 13 target. Meanwhile, North Korea recorded the highest incidence of tuberculosis in the region. Despite the fact that South Korea and Japan were the highest emitter of CO2, the duo had the lowest under five mortality, infant mortality, incidence of TB alongside the highest life expectancies which surpassed the regional performance. In view of the above, the policymakers in Asia and the rest of the countries with health insecurity should emulate the policymakers in Japan and South Korea by making adequate investment in health, education, and standard of living of their citizens.
    Matched MeSH terms: Carbon Dioxide/analysis
  9. Band gap engineered, oxygen-rich TiO2 for visible light induced photocatalytic reduction of CO2
    Tan LL, Ong WJ, Chai SP, Mohamed AR
    Chem Commun (Camb), 2014 Jul 4;50(52):6923-6.
    PMID: 24841282 DOI: 10.1039/c4cc01304b
    A facile and dopant-free strategy was employed to fabricate oxygen-rich TiO2 (O2-TiO2) with enhanced visible light photoactivity. Such properties were achieved by the in situ generation of oxygen through the thermal decomposition of the peroxo-titania complex. The O2-TiO2 photocatalyst exhibited high photoactivity towards CO2 reduction under visible light.
    Matched MeSH terms: Carbon Dioxide
  10. Composite amine mixed matrix membranes for high-pressure CO2-CH4 separation: synthesis, characterization and performance evaluation
    Fauzan NAB, Mukhtar H, Nasir R, Mohshim DFB, Arasu N, Man Z, et al.
    R Soc Open Sci, 2020 Sep;7(9):200795.
    PMID: 33047043 DOI: 10.1098/rsos.200795
    The key challenge in the synthesis of composite mixed matrix membrane (MMMs) is the incompatible membrane fabrication using porous support in the dry-wet phase inversion technique. The key objective of this research is to synthesize thin composite ternary (amine) mixed matrix membranes on microporous support by incorporating 10 wt% of carbon molecular sieve (CMS) and 5-15 wt% of diethanolamine (DEA) in polyethersulfone (PES) dope solution for the separation of carbon dioxide (CO2) from methane (CH4) at high-pressure applications. The developed membranes were evaluated for their morphological structure, thermal and mechanical stabilities, functional groups, as well as for CO2-CH4 separation performance at high pressure (10-30 bar). The results showed that the developed membranes have asymmetric structure, and they are mechanically strong at 30 bar. This new class of PES/CMS/DEA composite MMMs exhibited improved gas permeance compared to pure PES composite polymeric membrane. CO2-CH4 perm-selectivity enhanced from 8.15 to 16.04 at 15 wt% of DEA at 30 bar pressure. The performance of amine composite MMMs is theoretically predicted using a modified Maxwell model. The predictions were in good agreement with experimental data after applying the optimized values with AARE % = ∼less than 2% and R2 = 0.99.
    Matched MeSH terms: Carbon Dioxide
  11. Study on optical properties of cadmium sulphide quantum dots in various ph values and surface modification by thioglycolic acid
    Siti Aisyah Shamsudin, Jenniver Junas
    Sains Malaysiana, 2018;47:2841-2849.
    Pengimejan tradisi mempunyai banyak kekurangan seperti mempunyai jangka hayat yang pendek serta bersaiz besar
    kerana sifat pendafluornya tidak tahan lama atau berlakunya pelunturanfoto. Melalui kajian ini, nanohablur kadmium
    sulfida dihasilkan dan berfungsi sebagai pengimejan titik kuantum yang sesuai dengan sifat optiknya yang pelbagai
    mengikut saiz zarahnya. Sifat optik titik kuantum kadmium sulfida (TK CdS) boleh dipengaruhi oleh saiz dan juga
    komposisi kimia TK seperti perubahan pH. Dalam kajian ini, sifat optik TK CdS dikaji terhadap perubahan nilai pH
    dengan menghasilkan TK CdS melalui kaedah koloidal. Kadmium asetat dihidrat (C4
    H6
    CdO4
    .2H2
    O) dan natrium sulfida
    (Na2
    S) digunakan sebagai sebagai bahan pemula bagi menghasilkan TK CdS. Nilai pH diubah suai dengan menitiskan
    natrium hidroksida (NaOH) ke dalam larutan TK CdS. Lima jenis larutan disediakan iaitu pada nilai pH5, pH7, pH8,
    pH9 dan pH10. Masalah penggumpalan sering berlaku semasa proses sintesis CdS. Oleh itu, kajian ini menggunakan
    asid tioglikolik (HSCH2
    CO2
    H) sebagai agen penstabil kepada TK CdS. Spektra keserapan UV memberi anjakan biru
    apabila TK CdS pada pH alkali kerana saiz nanohablur mengecil. Hasil daripada spektroskopi pendarfluor mendapati
    larutan yang mempunyai nilai pH8 memberi puncak yang tertinggi. Hal ini adalah kerana pada pH ini nanohablur
    mampu berubah pada posisi yang tepat dan membentuk TK CdS pada kehabluran yang tinggi. Oleh itu, mekanisme ini
    dapat membentuk perangkap lubang dan seterusnya eksiton terbentuk.
    Matched MeSH terms: Carbon Dioxide
  12. Fulltext A Critical Review on the Properties and Applications of Sulfur-Based Concrete
    Fediuk R, Mugahed Amran YH, Mosaberpanah MA, Danish A, El-Zeadani M, Klyuev SV, et al.
    Materials (Basel), 2020 Oct 22;13(21).
    PMID: 33105753 DOI: 10.3390/ma13214712
    The incessant demand for concrete is predicted to increase due to the fast construction developments worldwide. This demand requires a huge volume of cement production that could cause an ecological issue such as increasing the rates of CO2 emissions in the atmosphere. This motivated several scholars to search for various alternatives for cement and one of such alternatives is called sulfur-based concrete. This concrete composite contributes to reduce the amount of cement required to make conventional concrete. Sulfur can be used as a partial-alternate binder to Ordinary Portland Cement (OPC) to produce sulfur-based concrete, which is a composite matrix of construction materials collected mostly from aggregates and sulfur. Sulfur modified concrete outperforms conventional concrete in terms of rapid gain of early strength, low shrinkage, low thermal conductivity, high durability resistance and excellent adhesion. On the basis of mentioned superior characteristics of sulfur-based concrete, it can be applied as a leading construction material for underground utility systems, dams and offshore structures. Therefore, this study reviews the sources, emissions from construction enterprises and compositions of sulfur; describes the production techniques and properties of sulfur; and highlights related literature to generate comprehensive insights into the potential applications of sulfur-based concrete in the construction industry today.
    Matched MeSH terms: Carbon Dioxide
  13. Bioprocessing of Chaetoceros calcitrans for the recovery of fucoxanthin using CO2-based alkyl carbamate ionic liquids
    Khoo KS, Ooi CW, Chew KW, Foo SC, Show PL
    Bioresour Technol, 2021 Feb;322:124520.
    PMID: 33348114 DOI: 10.1016/j.biortech.2020.124520
    Ionic liquids (ILs) have emerged as an alternative solvent used in the bioprocessing of microalgae for recovery of valuable biomolecules. The aim of this work is to extract fucoxanthin from Chaetoceros calcitrants (C. calcitrans) by using the readily distillable CO2-based alkyl carbamate ILs. The degree of cell permeabilization was analysed by the quantification of extracted fucoxanthin and the analyses of cell surface morphology. Among the tested CO2-based alkyl carbamate ILs, diallylammonium diallylcarbamate (DACARB) extraction system gave the maximal yield of fucoxanthin at 17.51 mg/g under the optimal extraction conditions [90% (v/v), 3 min and 25 °C]. Moreover, the extracted fucoxanthin fraction exhibited the satisfactory antioxidant activities. The recyclability of DACARB was demonstrated in the multiple batches of fucoxanthin extraction. Hence, CO2-based alkyl carbamate ILs can prospectively substitute conventional organic solvents in the downstream processing of bioactive compounds from microalgae.
    Matched MeSH terms: Carbon Dioxide
  14. Orange peel valorization by pyrolysis under the carbon dioxide environment
    Kwon D, Oh JI, Lam SS, Moon DH, Kwon EE
    Bioresour Technol, 2019 Aug;285:121356.
    PMID: 31005642 DOI: 10.1016/j.biortech.2019.121356
    To valorize biomass waste, pyrolysis of orange peel was mainly investigated as a case study. In an effort to establish a more sustainable thermolytic platform for orange peel, this study particularly employed CO2 as reactive gas medium. Accordingly, this study laid great emphasis on elucidating the mechanistic role of CO2 in pyrolysis of orange peel. The thermo-gravimetric analysis (TGA) confirmed that no occurrence of the heterogeneous reactions between the solid sample and CO2. However, the gaseous effluents from pyrolysis of orange peel experimentally proved that CO2 effectively suppressed dehydrogenation of volatile matters (VMs) evolved from the thermolysis of orange peel by random bond scissions. Moreover, CO2 reacted VMs, thereby resulting in the formation of CO. Note that the formation of CO was being initiated at temperatures ≥550 °C. The two identified roles of CO2 led to the compositional modification of pyrolytic oil by means of lowering aromaticity.
    Matched MeSH terms: Carbon Dioxide
  15. Unlocking Inter- to Non-Penetrating Frameworks Using Steric Influences on Spacers for CO2 Adsorption
    Huang SL, Zhang WH, Ling Y, Ng SW, Luo HK, Hor TS
    Chem Asian J, 2015 Oct;10(10):2117-20.
    PMID: 25965032 DOI: 10.1002/asia.201500231
    Four porous coordination networks have been synthesized from 1,4-benzenedicarboxylate with Cl, Br, I, and NO2 substituents whose different spatial differences are sufficient to influence the coordination mode of adjacent carboxyl moieties to unlock an inter-penetrating framework to give isostructural structures. Their size and polarity differences account for the diverging CO2 adsorption performances.
    Matched MeSH terms: Carbon Dioxide
  16. Fulltext Potential Mixture of Coir Fibre and Palm Kernel Shell in Concrete: A Review
    Noor Shafini Roslee, Salinah Dullah
    Borneo Journal of Medical Sciences, 2018;12(101):59-0.
    MyJurnal
    Globally, 998 million tonnes of agricultural waste is produced per year and in Malaysia, 1.2 million tonnes of agricultural waste is disposed of into landfills annually. Concurrently, increasing demands of concrete leads to vary of research conducted on improving cement production methods and formulating reduction or eliminate CO2 emissions.
    Matched MeSH terms: Carbon Dioxide
  17. Effect of water-to-cement ratio induced hydration on the accelerated carbonation of cement pastes
    Mehdizadeh H, Jia X, Mo KH, Ling TC
    Environ Pollut, 2021 Jul 01;280:116914.
    PMID: 33774540 DOI: 10.1016/j.envpol.2021.116914
    Recently, the use of accelerated carbonation curing has attracted wide attention as a promising method to reduce carbon dioxide (CO2) emission and improve the mechanical properties of cement-based materials. However, the diffusion mechanism of CO2 in the matrix and the content of hydration products are the key factors that restrict the carbonation reaction rate. To understand the combined behavior of hydration and carbonation reactions, this paper investigates the influence of cement hydration induced by water-to-cement ratio (w/c) (ranging from 0.25 to 0.45) on microstructure and microhardness properties of cement paste. The experimental results demonstrated that carbonation only occurred at the surface layer of cement paste samples and carbonation efficiency was significantly influenced by greater hydration due to higher w/c. The carbonation depth of the sample with 0.45 w/c was about 6 times higher than that of sample with 0.25 w/c after 28 days of CO2 curing. XRD results revealed that calcite-type calcium carbonate is the main carbonation product and consumption of clinker phases (C2S and C3S) during the hydration enhanced the calcite precipitation in the pores of the surface layer. According to FTIR, with increasing w/c, the position of Si-O-Si stretching bond of the carbonated surface changed from Q2 to Q3, confirming the formation of amorphous silica-rich gel, along with the appearance of CO32- bonds related to calcite. In overall, the micro-mechanical analysis in this study showed that the carbonation significantly improved the surface microhardness of cement paste samples, while the refinement of capillary pores due to carbonation also decreased the negative impact of large pores formed in the matrix of cement paste prepared with high w/c.
    Matched MeSH terms: Carbon Dioxide
  18. Effect of eggshell- and homo-type Ni/Al2O3 catalysts on the pyrolysis of food waste under CO2 atmosphere
    Valizadeh S, Ko CH, Lee J, Lee SH, Yu YJ, Show PL, et al.
    J Environ Manage, 2021 Sep 15;294:112959.
    PMID: 34116308 DOI: 10.1016/j.jenvman.2021.112959
    This study highlights the potential of pyrolysis of food waste (FW) with Ni-based catalysts under CO2 atmosphere as an environmentally benign disposal technique. FW was pyrolyzed with homo-type Ni/Al2O3 (Ni-HO) or eggshell-type Ni/Al2O3 (Ni-EG) catalysts under flowing CO2 (50 mL/min) at temperatures from 500 to 700 °C for 1 h. A higher gas yield (42.05 wt%) and a lower condensable yield (36.28 wt%) were achieved for catalytic pyrolysis with Ni-EG than with Ni-HO (34.94 wt% and 40.06 wt%, respectively). In particular, the maximum volumetric content of H2 (21.48%) and CO (28.43%) and the lowest content of C2-C4 (19.22%) were obtained using the Ni-EG. The formation of cyclic species (e.g., benzene derivatives) in bio-oil was also effectively suppressed (24.87%) when the Ni-EG catalyst and CO2 medium were concurrently utilized for the FW pyrolysis. Accordingly, the simultaneous use of the Ni-EG catalyst and CO2 contributed to altering the carbon distribution of the pyrolytic products from condensable species to value-added gaseous products by facilitating ring-opening reactions and free radical mechanisms. This study should suggest that CO2-assisted catalytic pyrolysis over the Ni-EG catalyst would be an eco-friendly and sustainable strategy for disposal of FW which also provides a clean and high-quality source of energy.
    Matched MeSH terms: Carbon Dioxide
  19. Identifying dominant environmental predictors of freshwater wetland methane fluxes across diurnal to seasonal time scales
    Knox SH, Bansal S, McNicol G, Schafer K, Sturtevant C, Ueyama M, et al.
    Glob Chang Biol, 2021 08;27(15):3582-3604.
    PMID: 33914985 DOI: 10.1111/gcb.15661
    While wetlands are the largest natural source of methane (CH4 ) to the atmosphere, they represent a large source of uncertainty in the global CH4 budget due to the complex biogeochemical controls on CH4 dynamics. Here we present, to our knowledge, the first multi-site synthesis of how predictors of CH4 fluxes (FCH4) in freshwater wetlands vary across wetland types at diel, multiday (synoptic), and seasonal time scales. We used several statistical approaches (correlation analysis, generalized additive modeling, mutual information, and random forests) in a wavelet-based multi-resolution framework to assess the importance of environmental predictors, nonlinearities and lags on FCH4 across 23 eddy covariance sites. Seasonally, soil and air temperature were dominant predictors of FCH4 at sites with smaller seasonal variation in water table depth (WTD). In contrast, WTD was the dominant predictor for wetlands with smaller variations in temperature (e.g., seasonal tropical/subtropical wetlands). Changes in seasonal FCH4 lagged fluctuations in WTD by ~17 ± 11 days, and lagged air and soil temperature by median values of 8 ± 16 and 5 ± 15 days, respectively. Temperature and WTD were also dominant predictors at the multiday scale. Atmospheric pressure (PA) was another important multiday scale predictor for peat-dominated sites, with drops in PA coinciding with synchronous releases of CH4 . At the diel scale, synchronous relationships with latent heat flux and vapor pressure deficit suggest that physical processes controlling evaporation and boundary layer mixing exert similar controls on CH4 volatilization, and suggest the influence of pressurized ventilation in aerenchymatous vegetation. In addition, 1- to 4-h lagged relationships with ecosystem photosynthesis indicate recent carbon substrates, such as root exudates, may also control FCH4. By addressing issues of scale, asynchrony, and nonlinearity, this work improves understanding of the predictors and timing of wetland FCH4 that can inform future studies and models, and help constrain wetland CH4 emissions.
    Matched MeSH terms: Carbon Dioxide
  20. Fulltext Effect of different extraction techniques on total phenolic content and antioxidant activity of Quercus infectoria galls
    Hasmida, M.N., Nur Syukriah, A.R., Liza, M.S., Mohd Azizi, C.Y.
    International Food Research Journal, 2014;21(3):1075-1079.
    MyJurnal
    In this work, the bioactive compounds which was obtained by extracting Quercus infectoria via two extraction methods; Soxhlet and supercritical carbon dioxide (SC-CO2) extraction, were analyzed using total phenolic content and DPPH (2,2-diphenyl-1-picryl hydrazyl) free radical scavenging activity analysis. The aim of this study is to compare the total phenolic content and antioxidant activity of Quercus infectoria extract acquired from SC-CO2 extraction with those from Soxhlet extraction method. The results showed the used of SC-CO2 extraction give the lowest extraction yield as compared to Soxhlet extraction. The selectivity of Q. infectoria extracts using SC-CO2 extraction was better which in contrast with Soxhlet extraction method since it shows higher total phenolic content (143.75 ± 1.06 mg GAE/g sample). This study also revealed that the extracts from both extraction methods can posses’ antioxidant activity and comparable to those obtained from commercial antioxidant.
    Matched MeSH terms: Carbon Dioxide
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