Remote sensing of spectral reflectance is a crucial parameter in precision agriculture. In particular, the visual color produced from reflected light can be used to determine plant health (VIS-IR) or ...attract pollinators (Near-UV). However, the UV spectral reflectance studies largely focus on non-crop plants, even though they provide essential information for plant-pollinator interactions. This literature review presents an overview of UV-reflectance in crops, identifies gaps in the literature, and contributes new data based on strawberry cultivars. The study found that most crop spectral reflectance studies relied on lab-based methodologies and examined a wide spectral range (Near UV to IR). Moreover, the plant family distribution largely mirrored global food market trends. Through a spectral comparison of white flowering strawberry cultivars, this study discovered visual differences for pollinators in the Near UV and Blue ranges. The variation in pollinator visibility within strawberry cultivars underscores the importance of considering UV spectral reflectance when developing new crop breeding lines and managing pollinator preferences in agricultural fields.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The growth and production of lipids in the green microalga Raphidocelis subcapitata immobilized in alginate gel are studied. The beads are made from alginate (2% w/v) and CaCl2 (1% w/v). The dry ...weight, the concentration of cells, and the lipid content are determined after dissolution of the beads in a sodium phosphate buffer. The results show that variations in biomass do not reflect variations in the number of cells in R. subcapitata. Cells divide more rapidly (Gc = 3.45 ± 0.3 days) than biomass is produced (Gm = 4.1 ± 0.4 days) during the exponential growth phase. Therefore, the average mass of the immobilized cells decreases until it reaches its minimum at the end of the exponential phase. Thus, during the stationary phase, cell division ceases while biomass production continues, and the average mass of the immobilized cells increases. In the present study, it is shown that this increase is due to the accumulation of lipids following the depletion of nitrates and phosphates in the culture medium. A lipid content of 24.7 ± 2.5% (dcw) and a lipid productivity of LP = 29.8 ± 3.0 mg/L/day are recorded at the end of culture. These results suggest that immobilized R. subcapitata has promising potential for biodiesel production.
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An innovative approach to selectively separating molecules and ions has been developed using polymer nanocomposite membranes that consist of a continuous polymer phase and a ...nanofiller phase. To address the challenges associated with filtration, we have developed and compared a nanofibrous cellulose acetate (CA)-based membrane reinforced with cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs). Several parameters including the morphologies, chemical interactions, and mechanical properties of the membranes were investigated after they were synthesized using the electrospinning technique and after they were heat treated. The polymer solutions were composed of various weight percentages of CNCs, 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO)-mediated oxidized CNFs (i.e., 0 wt% to 1 wt%), and 15 wt% of CA. Based on our study, the reinforcing properties of TOCNF nanofillers were superior to CNC nanofillers. Heat-treated 0.25TOCNF/CA composite nanofibrous membrane achieved maximum ultimate tensile strength and elongation at the breakpoint of 33.31 MPa and 1.8%, respectively. The process-structure-property relationships outlined in this study can facilitate the fabrication and application of electrospun nanocomposite membranes for the purification of water.
This paper provides a quantitative comparison between electrocoagulation and chemical precipitation based on heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) removal from acidic soil leachate (ASL) at the ...laboratory pilot scale. Chemical precipitation was evaluated using either calcium hydroxide or sodium hydroxide, whereas electrocoagulation was evaluated via an electrolytic cell using mild steel electrodes. Chemical precipitation was as effective as electrocoagulation in removing metals from ASL having low contamination levels (30mgPbl−1 and 18mgZnl−1). For ASL enriched with different metals (each concentration of metals was initially adjusted to 100mgl−1), the residual Cr, Cu, Pb and Zn concentrations at the end of the experiments were below the acceptable level recommended for discharge in sewage urban works (more than 99.8% of metal was removed) using either electrocoagulation or chemical precipitation. Cd was more effectively removed by electrochemical treatment, whereas Ni was easily removed by chemical treatment. The cost for energy, chemicals and disposal of metallic residue of electrocoagulation process ranged from US$ 8.83 to 13.95tds−1, which was up to five times lower than that recorded using chemical precipitation. Highly effective electrocoagulation was observed as the ASL was specifically enriched with high concentration of Pb (250–2000mgPbl−1). More than 99.5% of Pb was removed regardless of the initial Pb concentration imposed in ASL and, in all cases, the residual Pb concentrations (0.0–1.44mgl−1) were below the limiting value (2.0mgl−1) for effluent discharge in sewage works.
In force since 1994, the North American Free Trade Agreement (NAFTA) is still the most comprehensive agreement ever developed, conforming to the world’s largest trade market. However, the ...environmental impacts cannot be neglected, particularly greenhouse gas emissions. The environmental Kuznets curve (EKC) hypothesis is revisited, studying Canada, Mexico, and the U.S.A. in relation to carbon dioxide (CO2) emissions, gross domestic product (GDP), energy, and exergy consumption. Ordinary least squares, vector autoregression, and Granger causality tests are conducted. Additionally, exergy indicators and the human development index (HDI) are proposed. Results for Mexico and the U.S.A. describe similar and interesting outcomes. In the search of the environmental Kuznets curve (EKC), the EKC hypothesis is confirmed for Mexico and the U.S.A. However, for Canada, the EKC hypothesis does not stand. The Granger causality test displays the existence of a uni-directional causality running from CO2 emissions to economic growth; a similar behavior was observed while testing the for the exergetic control variables. The most intriguing Granger causal results are those from the U.S.A. A bidirectional relation was observed between exergy intensity and CO2 emissions. Moreover, the EKC curve was plotted by both variables. Furthermore, Mexico’s outcomes reveal that increasing renewable exergy share will decrease CO2 emissions. On the contrary, increasing HDI will grow CO2 emissions. Policy implications arise for NAFTA countries to minimize CO2 emissions by means of the growing renewable energy share. Exergy tools offer an appealing insight into energetic and environmental strategies.
A study of carbon dioxide sequestration has been performed in aqueous electric arc furnace (EAF) and ladle furnace (LF) slag suspensions, in leached hydrated-matrixes, and in leachates to estimate ...their intrinsic sequestration potential at ambient conditions (temperature of 20 ± 1 °C and atmospheric pressure). The CO2 sequestration was tested in aqueous suspensions of steel slags at a liquid-to-solid ratio of 10 kg/kg as well as in leached hydrated-matrixes and leachates isolated from these fresh slag suspensions after three consecutive leachings. The sequestration assays were performed at 20 °C with a flow rate of 5 mL/min of a CO2 concentration of 15.00 vol %. The results have revealed that the CO2 sequestration capacity of the LF slag suspension (24.7 g of CO2/100 g of slag) is 14 times superior to that of the EAF slag suspension. This greater CO2 sequestration capacity of the LF slag suspension may be associated in large part to its higher content of portlandite, which reacts with CO2 relative to the EAF slag suspension. Moreover, the separation of hydrated-matrixes and leachates significantly enhanced the CO2 sequestration capacity of EAF slag while a slight decrease was observed for the LF slags. This may be due to an obstruction of the CO2 binding sites of LF slag hydrated-matrixes following the accumulation of calcium carbonate. Taken together, these results suggest that EAF and LF slags could be used for the CO2 sequestration and given a good yield as well in aqueous suspension as in separated matrixes and leachates.
A study of carbon dioxide (CO2) absorption/desorption has been carried out to estimate the influence of the structural features of distinct amines on their CO2 absorption and regeneration. The ...absorption has been made at two different CO2 flow rates with a series of aqueous 5 wt % ammonia, monoethanolamine (MEA), triethanolamine (TEA), triethylamine, pyridine, pyrrolidine, 2-(2-aminoethylamino)ethanol (AEE), and N-(2-aminoethyl)-1,3-propanediamine (AEPDNH2) solutions, while the CO2 desorption has been performed by heating these solutions. The presence of two or three amino groups in AEE and AEPDNH2, the structure of tertiary amine and alkanolamine, and a nonaromatic ring of pyrrolidine might favor the CO2 absorption, while the structural features of ammonia and pyridine seem to be unfavorable. The tertiary alkanolamine is the most easy to regenerate and looses less of its CO2 loading after regeneration. It appears that AEE and AEPDNH2 would represent interesting compounds which could be used as CO2 absorbents in industrial technologies to prevent CO2 release into the atmosphere.
Diverse factors may have an impact in carbon dioxide (CO2) emissions; thus, three main contributors, energy consumption, gross domestic product (GDP) and an exergy indicator are examined in this ...work. This study explores the relationship between economic growth and energy consumption by means of the hypothesis postulated for the Environmental Kuznets Curve (EKC). Panel data for ten countries, from 1971 to 2014 have been studied. Despite a wide gamma of research on the EKC, the role of an exergy variable has not been tested to find the EKC; for this reason, exergy analysis is proposed. Exergy analyses were performed to propose an exergetic indicator as a control variable and a comparative empirical study is developed to study a multivariable framework with the aim to detect correlations between them. High correlation between CO2, GDP, energy consumption, energy intensity and trade openness are observed, on the other hand not statistically significant values for trade openness and energy intensity. The results do not support the EKC hypothesis, however exergy intensity opens the door for future research once it proves to be a useful control variable. Exergy provides opportunities to analyze and implement energy and environmental policies in these countries, with the possibility to link exergy efficiencies and the use of renewables.
Sewage sludge management is an energy intensive process. Anaerobic digestion contributes to energy efficiency improvement but is limited by the biological process. A review has been conducted prior ...to experimentation in order to evaluate the mass and energy balances on anaerobic digestion followed by gasification of digested sludge. The purpose was to improve energy recovery and reuse. Calculations were based on design parameters and tests that are conducted with the anaerobic digester of a local wastewater treatment plant and a small commercial gasification system. Results showed a very significant potential of energy recovery. More than 90% of the energy content from sludge was extracted. Also, approximately the same amount of energy would be transferred in both directions between the digester (biogas) and the gasifier (thermal energy). This extraction resulted in the same use of biogas as the reference scenario but final product was a totally dry biochar, which represented a fraction of the initial mass. Phosphorus was concentrated and significantly preserved. This analysis suggests that anaerobic digestion followed by dehydration, drying and gasification could be a promising and viable option for energy and nutrient recovery from municipal sludge in replacement of conventional paths.
Data and information quality have been recognized as essential components for improving business efficiency. One approach for the assessment of information quality (IQ) is the manufacturing of ...information (MI). So far, research using this approach has considered a whole document as one indivisible block, which allows document evaluation only at a general level. However, the data inside the documents can be represented as components, which can further be classified according to content and composition. In this paper, we propose a novel model to explore the effectiveness of representing data as a composite unit, rather than indivisible blocks. The input data sufficiency and the relevance of the information output are evaluated in the example of analyzing an administrative form. We found that the new streamlined form proposed resulted in a 15% improvement in IQ. Additionally, we found the relationship between the data quantity and IQ was not a “simple” correlation, as IQ may increase without a corresponding increase in data quantity. We conclude that our study shows that the representation of data as a composite unit is a determining factor in IQ assessment.
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