The nexus of renewable and nonrenewable energy consumption,trade openness,and CO2 emissions in the framework of EKC: evidence from emerging economies

Environmental Science and Pollution Research - Emerging economies are experiencing considerable economic changes due to change in energy demand and CO2 emissions. To explore the link between energy...     

Synthesis of [13C]- and [14C]-labeled phenolic humus and lignin monomers

Natural phenolic monomers are ubiquitous in the environment and are involved in the stabilization of atmospheric carbon and the transformation of xenobiotics. Investigations on the stabilization of phenolic carbons and their environmental fate are hampered by the unavailability of commercial [13C]- and [14C]-labeled phenols. Here we report the complete chemical synthesis of the lignin and humus structural monomers p-coumaric, ferulic, and caffeic acids, p-hydroxybenzaldehyde, protocatechualdehyde, vanillin, catechol, and guaiacol, uniformly [13C]- or [14C]-labeled in the aromatic ring, starting from commercially available [U-ring-13C]- or [U-ring-14C]-labeled phenol. The synthesis of these compounds involved selective ortho-hydroxylation of the aromatic ring, Friedel-Crafts alkylation, and Knoevenagel condensation. [U-ring-13C]- or [U-ring-14C]-p-coumaric acid was synthesized via p-hydroxybenzaldehyde with a 75% yield with respect to phenol. Synthesis of [U-ring-13C]- or [U-ring-14C]-ferulic acid, consisting of six single steps via guaiacol and vanillin, had an overall yield of up to 45%. Uniformly ring-labeled caffeic acid was synthesized either via catechol and protocatechualdehyde in five single steps, yielding [U-ring-14C]-caffeic acid with a 37% yield, or via guaiacol, vanillin, and ferulic acid in seven steps, yielding [U-ring-13C]-caffeic acid with an 18% yield. Ferulic acid, [14C]-labeled at beta-C of the propenoic side chain, was synthesized from [2-14C]-malonic acid under Knoevenagel conditions with a 67% yield with respect to malonic acid. Demethylation of the [beta-14C]-ferulic acid with BBr3 in CH3CN resulted in [beta-14C]-caffeic acid with a 62% yield. All [U-ring-13C]-labeled phenolic products were analyzed by 13C nuclear magnetic resonance (13C-NMR) spectroscopy and gas chromatography-mass spectrometry (GC-MS).     

Release of substituents from phenolic compounds during oxidative coupling reactions

Phenolic compounds originating from plant residue decomposition or microbial metabolism form humic-like polymers during oxidative coupling reactions mediated by various phenoloxidases or metal oxides. Xenobiotic phenols participating in these reactions undergo either polymerization or binding to soil organic matter. Another effect of oxidative coupling is dehalogenation, decarboxylation or demethoxylation of the substrates. To investigate these phenomena, several naturally occurring and xenobiotic phenols were incubated with various phenoloxidases (peroxidase, laccase, tyrosinase) or with birnessite (delta-MnO(2)), and monitored for chloride release, CO(2) evolution, and methanol or methane production. The release of chloride ions during polymerization and binding ranged between 0.2% and 41.4%. Using the test compounds labeled with 14C in three different locations (carboxyl group, aromatic ring, or aliphatic chain), it was demonstrated that 14CO(2) evolution was mainly associated with the release of carboxyl groups (17.8-54.8% of the initial radioactivity). Little mineralization of 14C-labeled aromatic rings or aliphatic carbons occurred in catechol, ferulic or p-coumaric acids (0.1-0.7%). Demethoxylation ranged from 0.5% to 13.9% for 2,6-dimethoxyphenol and syringic acid, respectively. Methylphenols showed no demethylation. In conclusion, dehalogenation, decarboxylation and demethoxylation of phenolic substrates appear to be controlled by a common mechanism, in which various substituents are released if they are attached to carbon atoms involved in coupling. Electron-withdrawing substituents, such as -COOH and -Cl, are more susceptible to release than electron-donating ones, such as -OCH(3) and -CH(3). The release of organic substituents during polymerization and binding of phenols may add to CO(2) production in soil.     

Re-evaluating the asymmetric conventional energy and renewable energy consumption-economic growth nexus for Pakistan

Environmental Science and Pollution Research - To understand the nexus between economic growth and energy sources, in this study, we have selected Pakistan and collected data over the period...     

Watering techniques and zero-valent iron biochar pH effects on As and Cd concentrations in rice rhizosphere soils, tissues and yield

Zero-valent iron amended biochar (ZVIB) has been proposed as a promising material in immobilizing heavy metals in paddy fields. In this study, the impacts of pH of ZVIB (pH 6.3 and pH 9.7) and watering management techniques (watering amount in the order of CON (control, 5/72)>3/72>1–3/72>3/100>1/72, with 5/72, for example, representing irrigation given to 5 cm above soil surface in 72 hr regular interval) on As and Cd bioavailability for rice and its grain yield (Yield_BR) were investigated in a pot experiment. Brown rice As (As_BR) content was irrelative to the watering treatments, while significantly decreased (>50%) with the addition of both ZVIB materials. The diminutions of brown rice Cd (Cd_BR) content as well as the Yield_BR were highly dependent on both the soil amendment materials’ pH and watering amount. Among all the watering treatments, 3/72 treatment (15% less irrigation water than the CON) with ZVIB 6.3 amendment was the optimum fit for simultaneous reduction of As_BR (50%) and Cd_BR contents (19%) as well as for significant increment (12%) of the Yield_BR. Although high pH (9.7) ZVIB application could also efficiently decrease As and Cd contents in brown rice, it might risk grain yield lost if appropriate (e.g. 3/72 in our study) watering management technique was not chosen. Therefore, ZVIB would be an environmentally friendly option as an amendment material with proper selection of watering management technique to utilize As and Cd co-contaminated arable soils safely for paddy cultivation.     

On-road emissions of CO, CO2 and NOX from four wheeler and emission estimates for Delhi

This study presents the emission factor of gaseous pollutants(CO, CO_2, and NO X) from on-road tailpipe measurement of 14 passenger cars of different types of fuel and vintage. The trolley equipped with stainless steel duct, vane probe velocity meter, flue gas analyzer, Nondispersive infra red(NDIR) CO_2 analyzer, temperature, and relative humidity(RH) sensors was connected to the vehicle using a towing system. Lower CO and higher NO X emissions were observed from new diesel cars(post 2010) compared to old cars(post 2005), which implied that new technological advancement in diesel fueled passenger cars to reduce CO emission is a successful venture,however, the use of turbo charger in diesel cars to achieve high temperature combustion might have resulted in increased NO X emissions. Based on the measured emission factors(g/kg), and fuel consumption(kg), the average and 95% confidence interval(CI) bound estimates of CO, CO_2,and NO X from four wheeler(4W) in Delhi for the year 2012 were 15.7(1.4–37.1), 6234(386–12,252),and 30.4(0.0–103) Gg/year, respectively. The contribution of diesel, gasoline and compressed natural gas(CNG) to total CO, CO_2 and NO X emissions were 7:84:9, 50:48:2 and 58:41:1respectively. The present work indicated that the age and the maintenance of vehicle both are important factors in emission assessment therefore, more systematic repetitive measurements covering wide range of vehicles of different age groups, engine capacity, and maintenance level is needed for refining the emission factors with CI.     

Ciprofloxacin adsorption from aqueous solution onto chemically prepared carbon from date palm leaflets

A chemically prepared carbon was synthesized from date palm leaflets via sulphuric acid carbonization at 160℃. Adsorption of ciprofloxacin (CIP) from aqueous solution was investigated in terms of time, pH, concentration, temperature and adsorbent status (wet and dry). The equilibrium time was found to be 48 hr. The adsorption rate was enhanced by raising the temperature for both adsorbents, with adsorption data fitting a pseudo second-order model well. The activation energy, E_a, was found to be 17 kJ/mol, indicating a diffusion-controlled, physical adsorption process. The maximum adsorption was found at initial pH 6. The wet adsorbent showed faster removal with higher uptake than the dry adsorbent, with increased performance as temperature increased (25-45℃). The equilibrium data were found to fit the Langmuir model better than the Freundlich model. The thermodynamic parameters showed that the adsorption process is spontaneous and endothermic. The adsorption mechanism is mainly related to cation exchange and hydrogen bonding.     

Tumor necrosis factor-alpha,prostaglandin-E2 and interleukin-1β targeted anti-arthritic potential of fluvoxamine: drug repurposing

Environmental Science and Pollution Research - Fluvoxamine, a selective serotonin re uptake inhibitor, is used to treat depression. The aim of present study was to evaluate fluvoxamine in acute...     

Effect of commercial formulation of four organophosphorus insecticides on the ovaries of a freshwater teleost, Mystus vittatus (bloch)--a histological and histochemical study

The chronic effect of an exposure to a sublethal concentration of commercial formulation of 4 organophosphorus insecticides such as birlane (chlorfenvinphos), gardona (tetrachlorvinphos), phosdrin (mevinphos) and malathion on midvitellogenic ovaries of Mystus vittatus was investigated using several histological and histochemical techniques. The loss of stage II and III oocytes accompanied by a significant decline in gonadosomatic index was recorded. The vitellogenesis in treated fishes was ceased as the oocytes did not advance to further stages as evidenced by the absence of lipid yolks and the lack of a PAS positive follicular layer. The RNA content of remaining stage I oocytes of exposed fishes resembled that of the stage I oocytes of the control fishes. The absence of delta 5-3 beta-hydroxysteroid dehydrogenase suggested the lack of steroidogenesis. Reduced glucose-6-phosphate dehydrogenase activity was also observed. The significance of these observations has been discussed in light of available literature.