Effects Of Various Environmental Conditions Research Articles

Degradation characteristics of the pineapple leaf fibre reinforced green composite developed by injection moulding under different environmental conditions

The present study examines the mechanical and morphological characteristics of a green composite reinforced with pineapple leaf fiber (PLF) under different environmental conditions. PLF underwent chemical treatment at optimal conditions, using a 1% w/v sodium carbonate solution for 6 hours, to produce an environmentally friendly pineapple leaf fiber (PLF)/polylactic acid (PLA)-based composite via injection molding. The optimal injection settings of 165℃ (melting temperature), 50 mm/sec (injection speed), and 110 bars (injection pressure) to produce the PLF/PLA composite. The PLF/PLA composite was developed with a fiber loading of 20% and a length of 3 mm. The produced PLF/PLA composites were then exposed to a variety of environmental conditions, including water, soil, refrigeration, and room temperature. The impact of these diverse conditions on the mechanical properties (tensile, flexural, compression, and shear) was scientifically observed for four-week. Additionally, the morphology of the fractured specimens was assessed using a scanning electron microscope (SEM). The contact angle measurement was conducted to assess the hydrophilic characteristics of the PLF/PLA green composite. There has been a lack of comprehensive research on the effects of different environmental conditions on the mechanical, wettability, and morphological properties of green composites derived from PLF/PLA. Thus, in this study, emphasis is given for investigating the effect of various environmental conditions on the mechanical properties of PLF/PLA injection-molded green composite. The composite material demonstrated the highest water absorption and swelling thickness at 6.45% and 5.51%, respectively, in comparison to the dry PLF/PLA samples. The green composite of PLF/PLA demonstrated excellent mechanical performance under ambient conditions compared to other environmental conditions. The PLF/PLA composite displayed a peak contact angle of 83.26° when subjected to soil burial conditions. On the contrary, the initial samples of the PLF/PLA composite displayed the minimum contact angle of 56.72°.

Real-time smart driver sleepiness detection by eye aspect ratio using computer vision

The purpose of this study is to determine the optimal eye aspect ratio (EAR) for a prototype capable of using computer vision techniques to detect driver sleepiness based on eyelid size changes. The prototype, developed with Raspberry Pi and OpenCV, provides a real-time evaluation of the driver's level of alertness. The prototype can accurately determine the onset of sleepiness by monitoring and detecting instances of prolonged eyelid closure. Due to the fact that the eye aspect ratios of different individuals vary in size, the system's accuracy may be compromised. For the first experiment, the research focuses on determining the optimal EAR threshold of the proposed prototype using a sample of 20 participants ranging in age from 20 to 30, 31 to 40, and 41 to 50 years old. The study also examines the effects of various environmental conditions, such as dark or nighttime settings and the use of spectacle. The optimal EAR threshold value, as dedicated by the first experiment, is 0.225 after testing 20 participants with and without eyeglasses in low and bright lighting and 7 participants with a 0.225 EAR threshold in dark and bright lighting environments. The result shows 100% precision.

A comprehensive review on adsorptive removal of azo dyes using functional materials

Abstract The shortage of freshwater resources caused by azo dye pollution is an acute global issue, which has a great impact on environmental protection and human health. Therefore, the use of new strategies for designing and synthesizing green, efficient, and economical materials for the removal of azo dyes is required. Among the various methods for removal of azo dyes, adsorption by using advanced functional materials, including nanomaterials, metal oxides, metal oxides–polymer composite, biomaterials, and porous materials, have attracted significant attention over the past few years because of their capabilities of brilliant removal efficiency, high selectivity, quick response, reversibility, flexibility in operation, and less harmful by-products. In this review, we report the adsorption of azo dyes and general design principles underlying the above-mentioned functional materials and, in particular, highlight the fundamental mechanisms and effect of various environmental conditions; also, current challenges and opportunities in this exciting field have been emphasized, including the fabrication, subsequent treatment, and potential future applications of such functional materials.

The effect of various environmental conditions on stabilization/solidification (S/S) of oil-contaminated soil using alkaline activation of granulated blast furnace slag (GBFS)

Alkali-activated materials (AAMs) have been proposed as sustainable alternatives to traditional stabilizers. This study investigated the effect of freeze-thaw and wet-dry conditions on the durability of oil-contaminated soil stabilized using alkaline activation of granulated blast furnace slag (GBFS). The effect of curing temperature on GBFS-based samples was also evaluated. The main goal was to provide a suitable platform for the use of this eco-friendly material to improve the durability of oil-contaminated soil. Based on unconfined compressive strength (UCS) results and micro and macro investigations, the formation and melting of ice lenses increased the freezing and thawing cycles of the holes and, as a result, the UCS of the GBFS-based samples decreased. As the wet-dry cycle increased to 3, the UCS rose and then decreased. Raising the amount of GBFS and reducing the amount of crude oil in the GBFS-based samples prevented a sharp decrease in UCS and improved durability by increasing the entanglement and connection of particles and creating a denser structure. Increasing the curing temperature by removing free water and accelerating the geopolymerization and hydration reactions caused a further rise in UCS. In general, this study showed the appropriate circumstances for using this stabilization method for crude oil-contaminated soils in different environmental conditions.

Degradation of DDT by a Novel Bacterium, Arthrobacter globiformis DC-1: Efficacy, Mechanism and Comparative Advantage

A novel bacterium, Arthrobacter globiformis DC-1, capable of degrading DDT as its sole carbon and energy source, was isolated from DDT-contaminated agricultural soil. The bacterium can degrade up to 76.3% of the DDT at a concentration of 10 mg/L in the mineral salt medium (MSM) within 1 day of incubation. The effects of various environmental conditions, such as the concentration of DDT, temperature, pH and additional carbon sources, on its growth and biodegrading capacity of DDT were investigated in the MSM. The A. globiformis DC-1 strain could efficiently grow and degrade DDT at a wide range of concentrations, with the maximum growth and degradation rate at 10 mg/LDDT, followed by inhibitory effects at higher concentrations (20 and 30 mg/LDDT). Mesophilic temperatures (25–30 °C) and a pH of 7–7.5 were the most suitable conditions for the growth and biodegradation. The presence of carbon sources significantly increased the growth of the DC-1 strain; however, degradation was inhibited in the present of glucose, sucrose and fructose, and peptone was determined to be the most appropriate carbon source for A. globiformis DC-1. The optimal DDT degradation (84.2%) was observed at 10 mg/LDDT, peptone as carbon source in pH 7.5 at 30 °C with 1 day of incubation. This strain could also degrade DDE, DDD and DDT simultaneously as the sole carbon and energy source, with degradation rates reaching 70.61%, 64.43% and 60.24% in 10 days, respectively. The biodegradation pathway by A. globiformis DC-1 revealed that DDT was converted to DDD and DDE via dechlorination and dehydrochlorination, respectively; subsequently, both DDD and DDE transformed to DDMU through further dechlorination, and finally, after ring opening, DDMU was mineralized to carbon dioxide. No intermediate metabolites accumulation was observed during the GC/MS analysis, demonstrating that the A. globiformis DC-1 strain can be used for the bioremediation of DDT residues in the environment.

Partitioning behavior and mechanism of polyhalogenated carbazoles in water and suspended particulate matter

Polyhalogenated carbazoles (PHCZs), known as new dioxin-like compounds, are a new class of emerging environmental contaminants that have received increasing attention in recent years due to their wide distribution and dioxin-like toxicity. This study investigated the partition characteristics and adsorption mechanisms of eight PHCZs in the aqueous phase and suspended particulate matter (SPM). The competitive impact of humic acid (HA) on the adsorption of PHCZs was revealed when the effects of various environmental conditions (HA, temperature, perturbation disturbance, and pH) behavior were explored. The key finding of this study is that SPM, which is its effective vector, could adsorb 70.7 % of ΣPHCZs. The equilibrium adsorption amount is ranked as 3,6-ICZ > 3,6-BCZ > 2,7-BCZ > 3,6-CCZ > 1,3,6,8-BCZ > 3-BCZ > 2-BCZ > CZ. The halogen species, the degree of halogenation, and the substitution position of the PHCZs influence the amount of adsorption, where the log Kow values, the steric effect (Es), and the density contribute the most to the amount of adsorption, and the specific adsorption mechanisms are van der Waals force, π-π, hydrogen bonding, and nonspecific hydrophobic interactions. The adsorption reaction of PHCZs by SPM is endothermic, and the amount of adsorption increases with increasing temperature, oscillation velocity, and decrease in pH. HA may reduce the adsorption sites of hydroxyl, carbonyl, amide groups, and π-π bonds on SPM for PHCZs, while the SPM@HA conjugates can provide new sites for the adsorption of PHCZs. According to the experimental findings of this study, SPM plays a significant role in contaminant transport. As a result, when conducting environmental investigations of PHCZs and even other hydrophobic contaminants, we must fully consider the level of contaminants present in SPM to reveal the ecological risks accurately.

The Effect of Various Environmental Conditions on the Impact Damage Behaviour of Natural-Fibre-Reinforced Composites (NFRCs)-A Critical Review.

Studies into environmental conditions and their effects on the properties of renewable materials are gaining significant attention in the research field, particularly for natural fibres and their resultant composites. However, natural fibres are prone to water absorption because of the hydrophilic nature of the fibres, which affects the overall mechanical properties of natural-fibre-reinforced composites (NFRCs). In addition, NFRCs are based mainly on thermoplastic and thermosetting matrices, which could be used in automobile and aerospace components as lightweight materials. Therefore, such components have to survive the maximum temperature and humid conditions in different parts of the world. Based on the above factors, through an up-to-date review, this paper critically discusses the effects of environmental conditions on the impact performance of NFRCs. In addition, this paper critically assesses the damage mechanisms of NFRCs and their hybrids by focusing more on moisture ingress and relative humidity in the impact damage behaviour of NFRCs.

The effects of photoperiod and temperature-related factors on maize leaf number and leaf positional distribution in the field.

Quantifying the effects of various environmental conditions on maize leaf number is essential to understanding the environmental adaptations and population structure of maize plants and for enhancing maize productivity. In this study, seeds of three temperate-adapted maize cultivars, each belonging to different maturity classes, were sown on eight different dates. Sowing dates ranged from the middle of April to early July, which allowed us to cover a wide range of environmental conditions. Random forest regression and multiple regression models with variance partitioning analyses were used to assess the effects of environmental factors on the number of leaves and their distributions on maize primary stems. We demonstrated that the total leaf number (TLN) increased in the three cultivars in the following order: FK139 < JNK728 < ZD958, and variations in TLN for each cultivar were 1.5, 1.76, and 2.75 leaves, respectively. The variation in TLN was ascribed to changes in LB (leaf number below the primary ear), which were higher than variations in LA (leaf number above the primary ear). Variations in TLN and LB were mainly affected by the photoperiod during growth stages V7 to V11, and differences in TLN and LB in response to different photoperiods ranged from 1.34 to 2.95 leaves h-l. Variations in LA was mainly affected by temperature-related factors. Therefore, the results of this study enhanced our current understanding of key environmental conditions that affect maize leaf numbers, and provides scientific support for the benefits of adjusting sowing dates and selecting suitable cultivars to mitigate the effects of climate change on maize production.

Size-Fractionated Weathering of Olivine, Its CO2-Sequestration Rate, and Ecotoxicological Risk Assessment of Nickel Release

Olivine, one of the most abundant silicates on earth, thermodynamically captures CO2 in relevant amounts during its dissolution. Upscaling the use of this mineral as a replacement for sand or gravel may contribute to reduce concentrations of greenhouse gasses in the atmosphere. However, the reliable quantification of weathering rates and prognoses for effects of various environmental conditions on weathering are lacking. This currently inhibits the monitoring, reporting and verification of CO2 capture and hampers the exploitation of the carbon dioxide removal economy. A mineral dissolution model was developed, and olivine weathering rates were directly coupled to particle sizes of the ground mineral. A particle size-dependent calculation approach, based on the shrinking core model, showed faster weathering rates as compared to a single-size, monodisperse approach. This provided a better underpinning of the prediction of the overall weathering and, consequently, the sequestration rate of CO2. Weathering of olivine releases nickel, which is incorporated in the mineral. The dissolution model was coupled to advanced biotic ligand models (BLM) for nickel in order to assess potential chronic ecotoxicological risks upon release in the environment. Predicted no-effect concentrations for nickel showed that both the release of Mg and the increase of pH following olivine weathering significantly lowers nickel ecotoxicity.

A State-of-the-Art Review on Innovative Geopolymer Composites Designed for Water and Wastewater Treatment.

There is nothing more fundamental than clean potable water for living beings next to air. On the other hand, wastewater management is cropping up as a challenging task day-by-day due to lots of new additions of novel pollutants as well as the development of infrastructures and regulations that could not maintain its pace with the burgeoning escalation of populace and urbanizations. Therefore, momentous approaches must be sought-after to reclaim fresh water from wastewaters in order to address this great societal challenge. One of the routes is to clean wastewater through treatment processes using diverse adsorbents. However, most of them are unsustainable and quite costly e.g. activated carbon adsorbents, etc. Quite recently, innovative, sustainable, durable, affordable, user and eco-benevolent Geopolymer composites have been brought into play to serve the purpose as a pretty novel subject matter since they can be manufactured by a simple process of Geopolymerization at low temperature, lower energy with mitigated carbon footprints and marvellously, exhibit outstanding properties of physical and chemical stability, ion-exchange, dielectric characteristics, etc., with a porous structure and of course lucrative too because of the incorporation of wastes with them, which is in harmony with the goal to transit from linear to circular economy, i.e., “one’s waste is the treasure for another”. For these reasons, nowadays, this ground-breaking inorganic class of amorphous alumina-silicate materials are drawing the attention of the world researchers for designing them as adsorbents for water and wastewater treatment where the chemical nature and structure of the materials have a great impact on their adsorption competence. The aim of the current most recent state-of-the-art and scientometric review is to comprehend and assess thoroughly the advancements in geo-synthesis, properties and applications of geopolymer composites designed for the elimination of hazardous contaminants viz., heavy metal ions, dyes, etc. The adsorption mechanisms and effects of various environmental conditions on adsorption efficiency are also taken into account for review of the importance of Geopolymers as most recent adsorbents to get rid of the death-defying and toxic pollutants from wastewater with a view to obtaining reclaimed potable and sparkling water for reuse offering to trim down the massive crisis of scarcity of water promoting sustainable water and wastewater treatment for greener environments. The appraisal is made on the performance estimation of Geopolymers for water and wastewater treatment along with the three-dimensional printed components are characterized for mechanical, physical and chemical attributes, permeability and Ammonium (NH4+) ion removal competence of Geopolymer composites as alternative adsorbents for sequestration of an assortment of contaminants during wastewater treatment.

Studies on flow properties of Bengal gram (Cicer arietinum) flour for effective handling and storage strategies

AbstractBengal gram flour is in great demand and has extensive application due to its nutritional, functional, and sensory properties. The study summarizes the characteristics and compared the flow behavior of two varieties of Bengal gram flour (P372 and P3043) with commercial Barik sample with respect to chemical composition, wettability, physical properties, shear properties, compressibility, and dynamic properties, along with particle size and shape. The result showed that the median particle size distribution of the Bengal gram flour samples ranged between 53.59 and 63.46 μm. More fine particles were found in commercial Barik sample (11.09 μm), and larger particles were found in P372 (118.07 μm) and P3043 (116.47 μm). Similarly, the particle shape (circularity) was found higher in P372 (0.84) and P3043 (0.73) as compared to the commercial Barik sample (0.65). The chemical composition of mainly fat (%) and protein (%) was higher and lower in commercial Barik sample, respectively, compared to P372 and P3043 Bengal gram flour. Wettability (contact angle) determined the solid–liquid interaction of Bengal gram flour, where the commercial Barik sample showed a higher contact angle compared to P372 and P3043. The flow properties of Bengal gram flour, that is, compressibility, shear, and dynamic measurements were analyzed using an FT4 powder rheometer. The results indicated better flow behavior of the two varieties P372 and P3043 compared to commercial Barik sample.Practical ApplicationsThe flow properties of Bengal gram flour are essential during the handling, processing, transportation, mixing, compression, and packaging. The consistent flow of flour without excessive dust generation and spillage during handling is of great concern in the food industry. The flow properties of flour characterize its behavior during handling, conveying and storage. It is crucial for the design of storage and conveying systems such as hopper and silos in order to maximize the use of discharge units to their design capacity to prevent expensive downstream handling problems. The practical application obtained from the comparative study would be useful to determine the effect of various environmental conditions on the flowability of Bengal gram flour. Thus, it provides critical factors in optimizing the processing, designing of equipment, hoppers, and silos used to produce Bengal gram flour in the food industry.

Effects of Various Environmental Conditions on the Growth of Amaranthus patulus Bertol. and Changes of Herbicide Efficacy Caused by Increasing Temperatures

Understanding the effects of climate change on weed growth and herbicide activity is important for optimizing herbicide applications for effective weed control in the future. Therefore, this study examined how climate change affects the growth of Amaranthus patulus and the efficacy of soil and foliar herbicides at different temperatures. Although the control values for A. patulus differed between herbicides and temperature, the control values increased with increasing time after the herbicide treatments. Under growth conditions in which the temperature remained constant, the efficacy of soil-applied herbicides, ethalfluralin, metolachlor, linuron, and alachlor, on A. patulus was highest when the weeds were grown at high temperature. In particular, 100% control values of A. patulus were achieved in response to metolachlor treatments at the total recommended dosage in growth chambers at 35 °C. The efficacy of foliar herbicides, glufosinate-ammonium, bentazone, and mecoprop, on A. patulus was also highest when the plant was grown at high temperature, except for glyphosate isopropylamine, which had similar efficacy rates regardless of the temperature. A. patulus was 100% controlled in response to glufosinate-ammonium, bentazone, and mecoprop at the recommended dosages in growth chambers at 30 and 35 °C. Under growth conditions in which the temperature changed from day to night, the efficacy of soil-applied herbicides, alachlor and linuron, on A. patulus was highest when the weeds were grown at high temperature. On the other hand, the efficacy of the soil-applied herbicides metolachlor and linuron on A. patulus was similar regardless of the temperature. The efficacy of foliar herbicides, glyphosate isopropylamine, glufosinate-ammonium, bentazone, and mecoprop, on A. patulus was highest when the weeds were grown at high temperature. Although herbicide efficacy varied depending on whether the weeds were grown at constant or alternating temperatures, herbicide efficacy was generally highest when the temperature was high.

Effects of environmental conditions on propanil degrading activity of &lt;i&gt; Acinetobacter baumannii&lt;/i&gt; DT

Effects of various environmental conditions on propanil degrading activity of Acinetobacter baumannii DT were investigated. Results showed that both propanil degradation and bacterial growth rate were reduced when bacteria were cultured in extreme conditions, such as high acidic or alkaline levels or high salinity. Moreover, the propanil degradation activity of A. baumannii DT decreased in contaminated water. The propanil dissipation rate was higher in herbicides-contaminated soil (treated soil) than in herbicide-free soil. In soil inoculated with A. baumannii DT, propanil removal was enhanced. Even though the propanil degrading activity of A. baumannii DT were reduced under extremely stressful conditions, this bacterium retained a good potential to degrade propanil in real environmental conditions.  

Agenator: An open source computer-controlled dry aging system for beef

<h2>Abstract</h2> Dry aging of beef is a process where beef is exposed to a controlled environment with the ultimate goal of drying the beef to improve its quality and value. Comprehensive investigations into the effects of various environmental conditions on dry aging are crucial for understanding and optimizing the process, but the lack of affordable equipment focused on data collection makes it difficult to do so. The Agenator was thus developed as an open source system with a suite of features for investigating dry aging such as: measuring and recording relative humidity, temperature, mass, air velocity, and fan rotational speed; precise control within 1% for relative humidity and 50 rpm for fan rotational speed; robust signal integrity preservation and data recovery features; modular design for easy addition and removal of individual chamber units; and non-permanent fixtures to allow easy adaptation of the system for other applications such as investigating dehydration of food products. The open source system comes with user-friendly computer software for interfacing with the system and creating sophisticated environmental control programs. The Agenator is available to the public at https://osf.io/87nck/.

Occupant perception of spectral light content variations due to glazing type and internal finish

Indoor Environmental Quality (IEQ) is a key issue in the design and renovation of any indoor building environment. It is comprised of different aspects (e.g. visual, thermal, acoustic comfort, etc.), which directly affect the building occupants’ wellbeing. Studies on this topic have grown rapidly in recent years, as the time that occupants spend indoors is increasing. In this regard, indoor luminous conditions are crucial for providing sufficient task illuminance as well as to stimulate the human circadian system. Insufficient lighting conditions have been proven to be related with reduced productivity/learnability, mood swings and health disorders, thus emphasizing the necessity for further research in this field. Therefore, proper performance evaluation criteria for managing and optimizing lighting spectral composition is needed. For instance, indoor lighting conditions can be evaluated by quantity, intensity, and/or uniformity, but also by spectral content, which determines the energy conveyed and the level at which the human body is stimulated. This spectral content can vary depending on the preferred or prevalent light source, interior finishes and glazing properties generating a singular indoor lighting environment. Thus, a preliminary study on the variation of the indoor daylight spectral content is conducted using a scaled model, applying various glazing types and interior finishes. Then, daylight simulations are performed on a calibrated virtual model to evaluate the effect of various environmental conditions. Results show a considerable impact of the interior finishes as well as glazing type on the attained circadian potential of studied indoor environment.

Isotope-labeling derivatization with 3-nitrophenylhydrazine for LC/multiple-reaction monitoring-mass-spectrometry-based quantitation of carnitines in dried blood spots

Carnitines are diagnostic biomarkers of fatty acid oxidation defects and organic acidemias. Quantitative measurements of various carnitines in dried blood spot (DBS) have potential use in remote health applications for disease diagnosis and epidemiological surveillance. To provide an improved LC/multiple-reaction monitoring (MRM)-MS method for quantitation of carnitines in DBS, 3-nitrophenylhydrazine (3NPH) was tested as a high-efficiency chemical isotope-labeling reagent for pre-analytical derivatization of 24 routinely-analyzed species. Reaction conditions were optimized and carnitine structural isomers were separated by reversed-phase LC with positive-ion MRM/MS detection, giving on-column lower LOQs of sub- to low-femtomole levels. 13C6-3NPH was used to produce 13C6- or 13C12-labeled derivatives of the mono- and di-carboxylic carnitines in a “one-pot” reaction. These labeled analogues were used as stable isotope-labeled internal standards to compensate for possible ESI matrix effects. Combined with an optimized, two-step procedure for the extraction of carnitines from DBS, this isotope-labeling derivatizaiton - LC/MRM-MS method provided good linearity, high precision (intra-day CVs of ≤7.8% and inter-day CVs of ≤8.8%) and high accuracy (three levels of standard substances spiked in, with recoveries of 86.9%–109.7%) quantitation of carnitines in three sets of DBSs on cellulose or cotton filter paper. This method was then applied to determine the concentration changes of the analytes in the DBSs under two stability-testing regimes: 1) a one-time 4-h sunlight exposure and 2) a set of cycled temperature transitions (−20 °C for 2 days, 40 °C for 2 days, and back to −20 °C for 2 additional days). All of the carnitines showed good stabilities under the first testing condition. Under the second testing condition, free carnitine showed concentration increases of 9.3%–16.1%; acetyl carnitine, 3-OH butyryl carnitine, and malonyl carnitine showed concentration decreases of 12.2%–17.3%, 12.9%–17.1% and 10.7%–15.3%, respectively, and other 20 acyl carnitines showed concentration changes of <10% in three sets of DBSs on cellulose or cotton filter paper. These preliminary stability-testing results indicate a need to more systematically investigate the effects of various environmental conditions on the chemical stabilities of carnitines in DBS specimens if this sampling method is to be used in remote health applications.

Atmospheric Corrosion of 904L Austenitic Stainless Steel at Different Environments

A major concern for metals and alloys in structural applications is susceptibility to atmospheric corrosion. The atmospheric corrosion behavior of 5 mm-thick 904L austenitic stainless steel (904L SS) coupons of dimensions 10 x 10 cm2 was studied as a part of a field exposure program for many alloys under a variety of environmental conditions that are existing in Qatar. Seven locations (stations) were selected to participate in this study representing desert, marine, coastal and industrial areas in Qatar. The study was implemented using image analyzer, scanning electron microscope (SEM) coupled with energy dispersive x-ray (EDAX) and electrochemical characterization techniques. The number of pits and pits’ depths and aspect ratios were calculated. Moreover, the thickness of oxide layer was detected using x-ray photoelectron spectroscopy (XPS). The analysis of the collected coupons revealed the corrosion behavior of 904L SS specimens and fasteners in various exposure conditions after different times of exposure. In addition, a correlation was made between the effects of various environmental conditions e.g. Cl-, and SO2 concentration in air and the extent and forms of corrosion. In general, 904L SS alloy formed several pits in the crevice regions and some pits also appeared on its flat surface, especially at marine and coastal industrial sites. Test coupons at desert test station didn’t form any corrosion products on its surface or around the crevice areas. It is clear that the number, the size and the aspect ratios of pits depend on the aggressiveness of the site’s environment. The pits’ density and aspect ratio were found to follow the following order; North field > Ras Laffan > Seaside Mesaieed > Industrial Mesaieed > Halul > Dukhan > Desert. Figure 1

Environmental Remediation and Application of Nanoscale Zero-Valent Iron and Its Composites for the Removal of Heavy Metal Ions: A Review.

The presence of heavy metals in the industrial effluents has recently been a challenging issue for human health. Efficient removal of heavy metal ions from environment is one of the most important issues from biological and environmental point of view, and many studies have been devoted to investigate the environmental behavior of nanoscale zerovalent iron (NZVI) for the removal of toxic heavy metal ions, present both in the surface and underground wastewater. The aim of this review is to show the excellent removal capacity and environmental remediation of NZVI-based materials for various heavy metal ions. A new look on NZVI-based materials (e.g., modified or matrix-supported NZVI materials) and possible interaction mechanism (e.g., adsorption, reduction and oxidation) and the latest environmental application. The effects of various environmental conditions (e.g., pH, temperature, coexisting oxy-anions and cations) and potential problems for the removal of heavy metal ions on NZVI-based materials with the DFT theoretical calculations and EXAFS technology are discussed. Research shows that NZVI-based materials have satisfactory removal capacities for heavy metal ions and play an important role in the environmental pollution cleanup. Possible improvement of NZVI-based materials and potential areas for future applications in environment remediation are also proposed.

Bacterial reduction of highly concentrated perchlorate: Kinetics and influence of co-existing electron acceptors, temperature, pH and electron donors

Perchlorate reduction kinetics and effects of various environmental conditions on removal of perchlorate from synthetic water were investigated to seek high-strength perchlorate removal using mixed perchlorate reducing bacteria. Results demonstrated that perchlorate (50–1500 mg L−1) could be degraded rapidly within 28 h under the optimal conditions. The maximum specific perchlorate reduction rate (qmax) and half saturation constant (Ks) were 0.92 mg-perchlorate (mg-dry weight)−1 h−1 and 157.7 mg L−1, respectively. In the ClO4−–NO3− systems obvious but recoverable lags were caused in perchlorate reduction and the lag time increased with the ratio of nitrate to perchlorate concentration increasing from 0.5 to 3. While in the ClO4−–SO42− systems inhibitions didn't occur until the ratio of sulfate to perchlorate concentration exceeded 10. The optimum temperature and pH value were 35 °C and 6.85, respectively. The optimal acetate-to-perchlorate ratio that could consume all perchlorate and acetate simultaneously was about 2. Dechloromonas, one of the most prominent perchlorate reducing bacteria, was identified as the dominant bacterium in the acclimated culture (69.33% of the whole clones). The study demonstrated that the perchlorate-acclimated mixed microorganisms can readily and efficiently realize reduction of highly concentrated perchlorate in wastewater.

Microkinetic modeling of the autoxidative curing of an alkyd and oil-based paint model system

Elucidating the curing and aging mechanisms of alkyd and other oil-based paints is valuable for the fields of conservation and bio-based coatings. Recent research has demonstrated the limitations of artificial aging in predicting the actual properties of paints that are hundreds of years old. Kinetic modeling offers pathways to develop a realistic and dynamic description of the composition of these oil-based paint coatings and facilitates the exploration of the effects of various environmental conditions on their long-term chemical stability. This work presents the construction of a kinetic Monte Carlo framework from elementary steps for the cobalt-catalyzed autoxidative curing of an ethyl linoleate model system up to the formation of single cross-links. Kinetic correlations for reaction families of similar chemistry are employed to reduce the number of parameters required to calculate rate constants in Arrhenius form. The model, developed from mechanisms proposed in the literature, shows good agreement with experiment for the formation of primary products in the early stages of curing. The model has also revealed that the mechanisms proposed in the literature for the formation of secondary products, such as volatile aldehydes, are still not well established, and alternative routes are under evaluation.