A Comparison of Modified and Unmodified Cellulose Nanofiber Reinforced Polylactic Acid (PLA) Prepared by Twin Screw Extrusion

The goal of this work was to evaluate the effect of chemical modification of cellulose nanofibers (CNF) on the properties of polylactic acid (PLA) nanocomposites. Acetylated nanofibers (ACNF), with degree of substitution 1.07, were isolated from acetylated kenaf fibers by mechanical treatments. Acetylated nanofibers showed more hydrophobic properties compared to non-acetylated ones. The results showed that both crystallinity and thermal stability of acetylated nanofibers were lower than non-acetylated ones. The nanocomposites were prepared by premixing two PLA master batches, one with a high concentration of ACNF and the second with CNF. These were diluted to final concentrations (5?wt%) during the extrusion. The morphology studies of PLA and its nanocomposites showed nanofiber aggregates in both materials. The results showed that the tensile and dynamic mechanical properties were enhanced for both acetylated and non-acetylated nanocomposites compared to the neat PLA matrix while no significant improvement was observed for the acetylated nanocomposites compared to non-acetylated ones. However, the storage modulus increased slightly for acetylated nanocomposites compared to non-acetylated ones.     

Modeling of road traffic noise and estimated human exposure in Fulton County, Georgia, USA

Environmental noise is a major source of public complaints. Noise in the community causes physical and socio-economic effects and has been shown to be related to adverse health impacts. Noise, however, has not been actively researched in the United States compared with the European Union countries in recent years. In this research, we aimed at modeling road traffic noise and analyzing human exposure in Fulton County, Georgia, United States. We modeled road traffic noise levels using the United States Department of Transportation Federal Highway Administration Traffic Noise Model implemented in SoundPLAN?. After analyzing noise levels with raster, vector and fa?ade maps, we estimated human exposure to high noise levels. Accurate digital elevation models and building heights were derived from Light Detection And Ranging survey datasets and building footprint boundaries. Traffic datasets were collected from the Georgia Department of Transportation and the Atlanta Regional Commission. Noise level simulation was performed with 62 computers in a distributed computing environment. Finally, the noise-exposed population was calculated using geographic information system techniques. Results show that 48% of the total county population [N=870,166 residents] is potentially exposed to 55 dB(A) or higher noise levels during daytime. About 9% of the population is potentially exposed to 67 dB(A) or higher noises. At nighttime, 32% of the population is expected to be exposed to noise levels higher than 50 dB(A). This research shows that large-scale traffic noise estimation is possible with the help of various organizations. We believe that this research is a significant stepping stone for analyzing community health associated with noise exposures in the United States.     

Behavioral and histological characterization of the effects of cigarette smoke inhalation and withdrawal in rats

Abstract

The aims of the study are to assess some effects of smoking for 3?months and of withdrawal of male weaned rats on anxiety, locomotor activity, and depression using common behavioral tests such as the marble burying, open field, and forced swim tests. Somatic signs of abstinence and histological effects were also studied. The rats present changes of the aforementioned behaviors as well as histological alterations of the lungs.     

Nonlinear molecular based modeling of the flash point for application in inherently safer design

New chemical process design strategies utilizing computer-aided molecular design (CAMD) can provide significant improvements in process safety by designing chemicals with required target properties and the substitution of safer chemicals. An important aspect of this methodology concerns the prediction of properties given the molecular structure. This study utilizes one such emerging method for prediction of a hazardous property, flash point (FP), which is in the center of attention in safety studies. Using such a reliable data set comprising 1651 organic and inorganic chemicals, from 79 diverse material classes, and robust dynamic binary particle swarm optimization for the feature selection step resulted in the most efficient molecular features of the FP investigations. Apart from the simple yet precise five-parameter multivariate model, the FP nonlinear behavior was thoroughly investigated by a novel hybrid of particle swarm optimization and support vector regression. Besides, 195 missing experimental FPs of the DIPPR data set are predicted via the presented procedure.     

The dynamic causal links between CO2 emissions from transport,real GDP,energy use and international tourism

This study examines the dynamic causality relationship between international tourism and carbon dioxide (CO₂) emissions from transport, real gross domestic product and energy use. The vector error correction model and Granger causality test approach have been used to investigate these relationships for the top ten international tourism destinations spanning the period 1995–2013. Results reveal a unidirectional causality running from CO₂ emissions to economic growth without feedback; a bidirectional causality between economic growth and energy use; a bidirectional causality between international tourism and economic growth; and a bidirectional causality between international tourism and energy use. They also suggest that energy use and international tourism both contribute to the decrease of emissions level coming from transport sector, while economic growth leads to the increase of CO₂ emissions. This study can be used in policy recommendations by encouraging countries to use clean energy and to stimulate tourism sector for combating global warming.     

Application of quadratic regression model for Fenton treatment of municipal landfill leachate

The effectiveness of Fenton process in municipal landfill leachate treatment, as a pre- or post-treatment approach, has been demonstrated. However, no general recommendations of universal validity could be made in the term of optimized conditions affecting Fenton process. At the first stage of this study, collected leachate samples from Aradkooh site, Tehran, Iran, were investigated using one-factor-at-a-time method to find out optimum coagulation pH and flocculation time values. Subsequently, the obtained results in addition to data issued previously by the authors were employed to develop a predictive model of the true response surface, namely chemical oxygen demand (COD) removal efficiency. Finally, the main parameters of Fenton procedure, i.e. initial pH, [H(2)O(2)]/[Fe(2+)] molar ratio, Fe(2+) dosage, and coagulation pH were optimized taking advantage of the above-mentioned quadratic model. The derived second-order model included both significant linear and quadratic terms and seemed to be adequate in predicting responses (R(2)=0.9896 and prediction R(2)=0.6954). It was found that the interaction between initial pH and Fe(2+) dosage has a significant effect on COD removal. While, the optimal [H(2)O(2)]/[Fe(2+)] molar ratio was independent of ferrous ion dosage. The optimum conditions for the maximum COD removal of 50.76% for the parameters of initial pH, [H(2)O(2)]/[Fe(2+)] molar ratio, Fe(2+) dosage, and coagulation pH were found to be 5.8, 8.0, 22,500mg/L, and 8.7 respectively.     

Sustainable wind‐driven bioventing at a petroleum hydrocarbon–impacted site

Bioventing—the injection of air into the vadose zone to increase microbial activity—is a commonly used, proven technology for remediating volatile organic compounds present in the vadose zone. Passive systems driven by wind or solar power are both more cost‐effective and sustainable than conventional systems. Such a passive system is being applied successfully to remediate a site impacted with total petroleum hydrocarbons (TPH) and benzene, toluene, ethylbenzene, and xylenes (BTEX) in soil. Bioventing technology was approved by the regulatory agency as an interim remedial action to remove chemicals of concern (COCs) in the vadose zone. A bioventing pilot study was conducted to evaluate the effectiveness of COC removal and collect parameters for full‐scale design and implementation. To evaluate the potential to use wind‐driven bioventing technology, two mobile weather stations were installed at the site and monitored for one month for a wind speed study. Based on the pilot‐test data and wind speed research, 12‐inch diameter funnel/vane 360‐degree wind collectors were designed as passive wind‐driven air‐injection devices and connected to existing monitoring wells. The measured air velocity ranged from 20 to 110 feet per minute during the start‐up and the first three months of operation and maintenance. Monitoring indicated a 20 percent oxygen delivery and greater than 90 percent reduction in COC concentrations, demonstrating a successful sustainable remediation with no power requirement and minimal operation and maintenance. © 2012 Wiley Periodicals, Inc.     

EVALUATION OF A LARGE SCALE IRRIGATION SYSTEM – DAIMCHEH,IRAN1

ABSTRACT: A study was conducted to evaluate the existing furrow irrigation system of Karun Agro Industry, a sugar cane plant in Daimcheh, Iran. Although the system is only eight years old, design and operational problems have reduced its efficiency by 50 percent. Lack of skilled irrigation workers, inadequate control of irrigation water, and problems with night irrigation have resulted in substantial revenue losses for the plant. This study evaluates the existing irrigation system, and recommends modifications and improvements to increase its efficiency. Final recommendations include the use of various irrigation methods, improvements to the existing system, and cancellation of night irrigation.     

Investigation on removal pathways of Di 2-ethyl hexyl phthalate from synthetic municipal wastewater using a submerged membrane bioreactor

Highly hydrophobic Di 2-ethyl hexyl phthalate (DEHP) is one of the most prevalent plasticizers in wastewaters. Since its half-life in biological treatment is around 25 days, it can be used as an efficiency indicator of wastewater treatment plant for the removal of hydrophobic emerging contaminants. In this study, the performance of submerged membrane bioreactor was monitored to understand the effect of DEHP on the growth of aerobic microorganisms. The data showed that the chemical oxygen demand (COD) and ammonia concentration were detected below 10 and 1.0 mg/L, respectively for operating conditions of hydraulic retention time (HRT) = 4 and 6 hr, sludge retention time (SRT) = 140 day and sludge concentration between 11.5 and 15.8 g volatile solid (VS)/L. The removal efficiency of DEHP under these conditions was higher and ranged between 91% and 98%. Results also showed that the removal efficiency of DEHP in biological treatment depended on the concentration of sludge, as adsorption is the main mechanism of its removal. For the submerged membrane bioreactor, the pore size is the pivotal factor for DEHP removal, since it determines the amount of soluble microbial products coming out of the process. Highly assimilated microorganisms increase the biodegradation rate, as 74% of inlet DEHP was biodegraded; however, the concentration of DEHP inside sludge was beyond the discharge limit. Understanding the fate of DEHP in membrane bioreactor, which is one of the most promising and futuristic treatment process could provide replacement for conventional processes to satisfy the future stricter regulations on emerging contaminants.     

Optimal water resources allocation in transboundary river basins according to hydropolitical consideration

Environment, Development and Sustainability - Water resources allocation policies can create cooperation or tension among different stakeholders in a large basin. Thus, integrated water resources...