The use of modified fly ash for preparing porous sound-absorbing materials and the optimum conditions of fly ash modification were studied. The effects of sintering temperature, sintering time, forming pressure, and other experimental conditions on porous sound-absorbing materials were also investigated. Results showed that the average volume density of the finished product was 0.93 g/cm³, the compressive strength was approximately 1.2 MPa, and the average porosity was nearly 60%. The average sound absorption coefficient of the sample in a low-frequency band was approximately 0.353, and the overall average sound absorption coefficient was nearly 0.458. The optimal preparation conditions were as follows: sintering temperature was 1100 °C, sintering time was 5 h, and molding pressure was 2 MPa.

This paper presents the oil-suspended particulate matter aggregate (OSA) resulted from the interaction of droplets of dispersed oil in a water column and particulate matter. This structure reduces the adhesion of oil on solid surfaces, promotes dispersion, and may accelerate degradation processes. The effects of the addition of fine sediments (clay + silt) on the formation of OSA, their impact on the dispersion and degradation of the oil, and their potential use in recovering reflective sandy beaches were evaluated in a mesoscale simulation model. Two simulations were performed (21 days), in the absence and presence of fine sediments, with four units in each simulation using oil from the Recôncavo Basin. The results showed that the use of fine sediment increased the dispersion of the oil in the water column up to four times in relation to the sandy sediment. There was no evidence of the transport of hydrocarbons in bottom sediments associated with fine sediments that would have accelerated the dispersion and degradation rates of the oil. Most of the OSA that formed in this process remained in the water column, where the degradation processes were more effective. Over the 21 days of simulation, we observed a 40 % reduction on average of the levels of saturated hydrocarbons staining the surface oil.

Efficient abatement of an iodinated X-ray contrast media iohexol by an emerging sulfite autoxidation advanced oxidation process is demonstrated, which is based on transition metal ion–catalyzed autoxidation of sulfite to form active oxidizing species. The efficacy of the combination of sulfite and transition metal ions (Ag(I), Mn(II), Co(II), Fe(II), Cu(II), Fe(III), or Ce(III)) was tested for iohexol abatement. Co(II) and Cu(II) are proven to show more pronounced catalytic activity than other metals at pH 8.0. According to the quenching studies, sulfate radical (SO₄•⁻) is identified to be the primary species for oxidation of iohexol. Increasing dosages of metal ion or sulfite and higher pH values are favorable for iohexol abatement. Inhibition of iohexol abatement is observed in the absence of dissolved oxygen, which is vital for the production of SO₅•⁻ and subsequent formation of SO₄•⁻. Overall, activation of sulfite to produce reactive radicals with extremely low Co(II) or Cu(II) concentrations (in the range of μg L⁻¹) in circumneutral conditions is confirmed, which offers a potential SO₄•⁻-based advanced oxidation process in treatment of aquatic organic contaminants.

The environmental Kuznets curve (EKC) hypothesis which was developed by Grossman and Krueger implies that clean environment demand increases over a certain level of income. Convergence of carbon emission can be considered an extension of EKC hypothesis, which emphasizes that the carbon emissions of countries will converge to a certain level. Convergence is important for the identification of the trend of carbon emission and to design emission abatement policies. This study investigates the stochastic convergence of per capita carbon emission in Organization for Economic Co-operation and Development (OECD) countries for 1960–2014 under cross-sectional dependence by using recently developed panel data methods. Empirical results are as follows: (i) per capita carbon emission is generally non-stationary according to the CADF test and the CIPS test. (ii) Panel KPSS test indicates that carbon emission per capita is overwhelmingly stationary in both country-specific and panel levels; (iii) Fourier panel KPSS test indicates that per capita carbon emission is overwhelmingly stationary at the country-specific level and non-stationary at the panel level. These findings are strongly in favor of convergence of per capita carbon emission among OECD countries. Consequently, it can be said that emission abatement policies aren’t essential among these countries.

Paraoxonase 1 (PON1) is an A-esterase calcium-dependent enzyme that is associated with high-density lipoprotein (HDL) and capable of hydrolyzing a wide variety of substrates, including organophosphate (OP) pesticides. The PON1 phenotype can be modulated by multiple internal and external factors, thereby affecting the catalytic capacity of the enzyme. The aim of this study was to evaluate factors that could modulate PON1 activity in a sample occupationally exposed to pesticides. A cross-sectional, descriptive, and analytical study was carried out with 240 workers. The participants were stratified according to their level of pesticide exposure as reference, moderate-exposure, and high-exposure groups. PON1 activities (arylesterase/AREase, CMPAase, and ssPONase (salt-stimulated)) were determined by spectrophotometry, and the Q192R and L55M PON1 genotypes by real-time PCR. The most frequent genotypes were heterozygous (QR) and homozygous (LL) for PON1Q192R and PON1L55M polymorphisms, respectively. The internal factors associated with the activity of PON1 were the PON1 genotypes (55 and 192) and biochemical parameters related to the lipid profile, in contrast, various external factors related to diet and harmful habits as well as with exposure to pesticides were associated with the activity of PON1. However, using a multivariate mixed ordinal regression model, we found a significant reduction of ssPONase activity in the high-exposure group compared with the reference group only in haplotypes QQLL and RRLL.

This study investigates the possible environmental effects of economic openness, such as economic growth, foreign direct investment (FDI) inflows, and trade liberalization in South Asian Association for Regional Cooperation (SAARC) countries. The study employed panel autoregressive lag distribution (ARDL) model to evaluate the environmental effects of economic openness; causality test was also conducted to confirm short- and long-run causality among the variables under discussion. The results show that trade, FDI, capital, and economic growth in the long run have a positive correlation with environmental degradation in SAARC countries while FDI, capital, and trade inflows have a negative relation with CO₂ emissions in the short run. Furthermore, economic growth by creating new job opportunities improved emissions also in the short run. FDI, trade, capital, and GDP have long-run causality with CO₂ emissions. Bidirectional causality was found between GDP and CO₂ emissions, unidirectional causality was also running from FDI inflows to economic growth, unidirectional causality running from capital to FDI and trade to capital. Finally, trade and economic growth also have unidirectional causality in the short run. This study concludes, therefore, that SAARC countries should invest in green energy and promote green trade liberalization.

The PM₂.₅ as one of the main pollutants in Tehran city has a devastating effect on human health. Knowing the key parameters associated with PM₂.₅ concentration is essential to take effective actions to reduce the concentration of these particles. This study assesses the relationship between meteorological (humidity, pressure, temperature, precipitation, and wind speed) and environmental parameters (normalize difference vegetation index and land surface temperature of MODIS satellite data) on PM₂.₅ concentration in Tehran city. The Geographically Weighted Regression (GWR) was employed to assess the impact of key parameters on PM₂.₅ concentrations in winter and summer. For this purpose, first the seasonal average of meteorological data were extracted and synchronized to satellite data. Then, using the ordinary least square model, the important parameters related to PM₂.₅ concentration were determined and evaluated. Finally, using the GWR model, the relationships between parameters related to PM₂.₅ concentration were analyzed. The results of this study indicate that meteorological and environmental parameters in winter season (71%) have a much higher ability to explain PM₂.₅ concentration than summer season (40%). In winter, PM₂.₅ concentration has a negative correlation with vegetation at most parts of the study area, a negative correlation with LST in the western and a positive correlation in the eastern part of the study area, a positive correlation with temperature, and a negative correlation with wind speed in the northeastern part of the study area. Precipitation has a positive correlation with PM₂.₅ concentration in most parts of the study area in both seasons. But, it was investigated in case of higher precipitation (more than 2 mm), PM₂.₅ concentration decreases. But, there is no negative relationship in any of the dependent parameters with PM₂.₅ concentration in summer. In this season, the air temperature parameter showed a high correlation with PM₂.₅ concentration. Also, spatial variations of the local coefficients for all parameters are higher in winter than in summer.

A combined use of silver nanoparticles (AgNPs) with different types of disinfectants as antimicrobial might be useful in mitigating the problem of development of bacterial resistance with a strong enhancement of the biocidal effect of disinfectants. To evaluate the biocidal activity of silver nanoparticles and its loaded forms, five commercial disinfectants (quaternary ammonium compounds (benzalkonium chloride (BC) and TH⁴⁺), Virkon®S, sodium hypochlorite, and hydrogen peroxide (H₂O₂)) were used against Listeria monocytogenes (L. monocytogenes) isolates at different concentrations and exposure times to reveal intra-species variability and the percentage of resistance to antimicrobial agents used. Therefore, a total of 260 specimens from animal and human stool as well as environmental samples from dairy cattle farms were cultured for isolation of L. monocytogenes. Thereafter, bacterial isolates were identified using PCR. Silver nanoparticle was synthesized using chemical reduction. Both silver nanoparticles and its loaded forms were characterized by transmission electron microscopy (TEM). The sensitivity test of 60 strains of L. monocytogenes bacteria to AgNPs and its loaded forms was evaluated using broth macrodilution method. Virkon®S/AgNPs 2.0% exhibited the highest bactericidal effect (100%) against L. monocytogenes strains followed by H₂O₂/AgNPs 5.0% and TH⁴⁺/AgNPs 1.0% (90% each). Furthermore, the percentage of resistance of L. monocytogenes was 0.0% to both H₂O₂/AgNPs 5.0% and Virkon®S/AgNPs 2.0%. In conclusion, monitoring the main source of contamination with Listeria monocytogenes in dairy cattle farms is an essential factor to achieve an efficient control. Moreover, the use of the disinfectants, Virkon®S 2.0%, H₂O₂ 5.0%, and TH⁴⁺1.0%, loaded on silver nanoparticles composite had the strong bactericidal effect against L. monocytogenes.

In this study, poly(ethylene terephthalate) fibers grafted with 4-vinyl pyridine (PET-g-4VP) was synthesized with using a radical polymerization method and its removal capacity for bromate ions in the aqueous solution was explored. The synthesized graft copolymer was structurally characterized by scanning electron microscopy (SEM) and Fourier transformed infrared spectroscopy (FTIR). The effect of some parameters such as pH, grafting rate, processing time, and ion concentration on bromate removal was examined with batch experiments. The sorptions of bromate onto the PET-g-4VP fibers were both verified with FTIR and X-ray fluorescence analysis (XRF) and the remaining amount of bromate after adsorption process was determined with an ion chromatography (Shimadzu). Moreover, kinetic and isotherm studies were also performed for adsorption of bromate with the grafted fibers. The point of zero charge (pHₚzc) of the PET-g-4VP fibers was found to be 7.5 and the fibers removed maximum amount of bromate from aqueous solution at pH 3. Equilibrium time of adsorption was determined to be 75 min and the adsorption kinetic was found to be pseudo-second-order model. It was observed that the increase in the amount of grafted 4VP onto the PET fibers increased the bromate removal capacity of the fibers; however, when the grafting yield of 4VP was over 80%, the bromate removal ability of the fibers decreased. The maximum bromate removal capacity of the PET-g-4VP was determined to be 183 mg/g when the initial bromate amount was 800 mg/L, treatment time was 75 min, pH of the solution was 3, and 4VP grafting yield was 80%. When the initial bromate concentration was higher than 800 mg/L, the removal rate of the PET-g-4VP fibers was not changed. In addition, bromate ion adsorption data indicated compliance with the Freundlich isotherm. The adsorbent fibers obtained by this study may be promising candidates for the removal of bromate ions from the aqueous media.

Nitrogen and phosphate dynamics in groundwater and surface waters (aquaculture ponds and effluents and drainage channels) in the two seasons (April and September 2015) were investigated in a reclaimed coastal region in China. Multiple isotopes (δ¹⁵N-NO₃⁻, δ¹⁸O-NO₃⁻, δ²H-H₂O, and δ¹⁸O-H₂O) associated with the concentrations of dissolved inorganic nitrogen and phosphate were analyzed to assess the environmental impact of mariculture on coastal waters. Low phosphate concentration in the effluents was released from aquaculture ponds. Nitrate accounted for a larger proportion of dissolved inorganic nitrogen in September in aquaculture ponds and effluents and drainage channels. The groundwater in the mariculture zone was enriched with dissolved nitrogen components. In the offshore direction, seawater and precipitation were supplement of the groundwater, with nitrate deriving from mixing aquaculture effluents and wastewater. Denitrification occurred in groundwater in September 2015.