Gasoline Combustion Research Articles

A skeletal mechanism for gasoline surrogates: Development, validation, and CFD application

In this study, a skeletal chemical kinetic mechanism for gasoline surrogates is developed from a detailed mechanism by applying several reduction techniques. Directed relation graph (DRG) routines and DRG-aided sensitivity analysis methods are applied with worst-case error tolerances equal to 30% and 40%, respectively. Issues with reaction dead-ends in the oxidation paths are resolved by adding adequate intermediate species and reactions. Sensitivity analyses are conducted to identify the most impactful fuel-dependent reactions to ignition delay, and the specific reaction rates of such reactions are optimized to replicate the ignition behavior of detailed mechanism. The final version of the skeletal mechanism consists of 152 species and 563 reactions including NOx chemistry. Experiments are carried out in Sandia's low-temperature gasoline combustion research engine with an E10 regular-grade gasoline, termed RD5-87, and the results are replicated in 0D simulations with good accuracies using both detailed mechanism and the skeletal mechanism although a slight over-estimation of the low-temperature heat release is observed. Finally, the performance of the skeletal mechanism is also tested in 3D CFD simulation using LES. Simulations are able to predict the pressure evolution and heat release rate, proving that the proposed skeletal mechanism is adequate for simulations.

Replicating HCCI-like autoignition behavior: What gasoline surrogate fidelity is needed?

This work seeks to characterize the fidelity needed in a gasoline surrogate with the intent to replicate the complex autoignition behavior exhibited within advanced combustion engines, and specifically Homogeneous Charge Compression Ignition (HCCI). A low-temperature gasoline combustion (LGTC) engine operating in HCCI mode and a rapid compression machine (RCM) are utilized to experimentally quantify fuel reactivity, through autoignition and preliminary heat release characteristics. Fuels considered include a research grade E10 U.S. gasoline (RD5-87), three multi-component surrogates (PACE-1, PACE-8, PACE-20), and a binary surrogate (PRF88.4). Each fuel was studied at lean/HCCI-like conditions covering a wide range of temperatures and pressures that are representative of naturally aspirated to high boost engine operation. Detailed chemical kinetic modeling is also undertaken using a recently updated gasoline surrogate kinetic model to simulate the RCM experiments and to provide chemical insight into surrogate-to-surrogate differences.The LGTC engine experiments demonstrate nearly identical reactivity between PACE-20 and RD5-87 across studied conditions, while faster phasing is seen for both PACE-1 and PACE-8 due to their stronger intermediate- and low-temperature heat release (ITHR/LTHR) at naturally aspirated and boosted conditions, respectively. The RCM experiments reveal typical low-temperature, negative temperature coefficient (NTC) and intermediate-temperature autoignition behaviors at all pressure conditions for RD5-87, which are qualitatively reproduced by all surrogates. Quantitative discrepancies in both autoignition and preliminary heat release are observed for all surrogates, while their ability to replicate RD5-87 autoignition behavior follows the order of PACE-20 > PACE-1 > PACE-8 > PRF88.4. Excellent mapping is obtained between the LGTC engine and the RCM, where the engine pressure-time trajectories can be characterized by the regimes represented by the RCM autoignition isopleths. The kinetic model performs commendably when simulating both autoignition and preliminary heat release of PACE-20, while typically overpredicting ignition delay times for PACE-1, PACE-8 and PRF88.4 at high-pressure and low-temperature/NTC conditions. Sensitivity and rate of production (ROP) analyses highlight surrogate-to-surrogate differences in the governing chemical kinetics where n-pentane initiates rapid OH branching at a faster rate and an earlier timing for PACE-20 than iso-pentane does for PACE-1 and PACE-8, making it computationally more reactive than the other surrogates. The current study highlights the need to include non-standardized properties, such as the lean/HCCI-like autoignition characteristics, in addition to ASTM properties (e.g., RON, MON) as metrics of fuel reactivity and targets to be matched when formulating high-fidelity surrogates that fully capture gasoline advanced combustion behavior such as HCCI-like autoignition.

Whey protein protects liver mitochondrial function against oxidative stress in rats exposed to acrolein.

Acrolein (AC) is one of the most toxic environmental pollutants, often associated with incomplete combustion of petrol, wood, and plastic, oil frying, and tobacco smoking, that causes oxidative damage to DNA and mitochondria. Considering that little is known about the protective effects of whey protein (WP) against AC-induced liver toxicity, the aim of our study was to learn more about them in respect to liver mitochondrial oxidative stress, respiratory enzymes, Krebs cycle enzymes, and adenosine triphosphate (ATP). To do that, we treated Sprague Dawley rats with daily doses of AC alone (5 mg/kg bw in 0.9 % NaCl solution), WP alone (200 mg/kg bw, in 0.9 % NaCl solution), or their combination by oral gavage for six days a week over 30 days. As expected, the AC group showed a drop in glutathione levels and antioxidant, transport chain, and tricarboxylic acid cycle enzyme activities and a significant rise in mitochondrial lipid peroxidation and protein carbonyl levels. Co-treatment with WP mitigated oxidative stress and improved enzyme activities. Judging by the measured parameters, WP reduced AC toxicity by improving bioenergetic mechanisms and eliminating oxidative stress.

Utilization of Selected Nanoparticles (Ag2O and MnO2) for the Production of High-Quality and Environmental-Friendly Gasoline

Nowadays, the devastating effects of the pollutants produced by gasoline are known well. As a result, scientists are looking for a better formula to replace the gasoline currently in use. Using different additives has been one of the strategies developed throughout the years. However, because certain compounds damage the environment and human life, researchers must now choose which additives to use. The primary goal of this work is to test a gasoline combination with nano-additives Ag2O and MnO2 in a 4-stroke vehicle engine (Fiat 128) and to investigate the influence of novel mixes on the efficiency of combustion rates and the amount of target pollutant gas released (CO, NOx, and the exhaust temperature). The tests were carried out at three different engine speeds: 2000, 2500, and 2900 rpm. At the end of the test, the 0.05% concentration of Ag2O nano-additive was chosen as the best sample, which increases engine performance in gasoline combustion rates and minimizes harmful gas emissions. Furthermore, CO and NOx emissions were lowered by 52% and 35%, respectively, according to EURO 6, indicating a considerable reduction in mortality rates and costs. Finally, a new mechanism was observed using Ag2O nanoparticles, leading to a reduction in CO and CO2 at the same time.

Effects of Biofuels on Soot and NO Formation during Gasoline Combustion

Effects of Biofuels on Soot and NO Formation during Gasoline Combustion

THE EFFECT OF SPARK PLUG GROUND ELECTRODE ON SPARK IGNITION ENGINE PERFORMANCE

Motorcycle performance is influenced by many factors, including combustion chamber dimension, fuel characteristic, type of spark plug, spray flame, ignition timing, and the combustion chamber's cooling system to avoid incomplete combustion and knocking processes. The spark plug is an essential component of SIE. Several studies, such as spark plug gap, material type, multiple-ground Electrode, roughness, etc., have been conducted to examine the effect of spark plug modifications on the combustion process. Some previous research investigates the impact of a multiple-ground electrode spark plug in biofuel combustion. However, a study about the effect of multiple-ground electrode spark plugs on the gasoline combustion process has not been conducted. This research was conducted to determine the impact of multiple-ground electrode on Supra 125 cc performance. The data displayed in this study are power, torque, BHP, and BMEP in single, double, and triple ground electrode. The results showed that the double ground electrode spark plug produced better performance than other variations.

Size distribution, meteorological influence and uncertainty for source-specific risks: PM2.5 and PM10-bound PAHs and heavy metals in a Chinese megacity during 2011–2021

This study aims at exploring size distribution, meteorological influence and uncertainty for source-specific risks of atmospheric particulate matter (PM), which can improve risk-mitigation strategies for health protection. Heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) in PM2.5 and PM10 were detected in a Chinese megacity during 2011–2021. A new method named as PMFBMR, which combines the Positive Matrix Factorization, Bootstrapping, Mote Carlo and Risk assessment model, was developed to estimate uncertainty of source-specific risks. It was found that PAH risks concentrated in fine PM, while HMs showed high risks in both fine and coarse PMs. For PM2.5, HQ (non-cancer risk hazard quotient) of gasoline combustion (GC), diesel and heavy oil combustion (DC), coal combustion (CC), industrial source (IS), resuspended dust (RD) and secondary and transport PM (ST) were 0.6, 1.4, 0.9, 1.6, 0.3, and 0.3. ILCR (lifetime cancer risk) of sources were IS (9.2E-05) > DC (2.6E-05) = CC (2.6E-05) > RD (2.2E-05) > GC (1.7E-05) > ST (6.4E-06). PM2.5 from GC, DC, CC and IS caused higher risks than coarse PM, while coarse PM from RD caused higher risks. Source-specific risks were influenced not only by emissions, but also by meteorological condition and dominant toxic components. Risks of GC and DC were usually high during stable weather. Some high risks of CC, IS and RD occurred at strong WS due to transport or wind-blown resuspension. GC and DC risks (influenced by both PAHs and HMs) showed strong relationship with T, while IS and RD risks (dominated by HMs) showed weak link with meteorological conditions. For uncertainty of source-specific risks, HQ and ILCR were sensitive for different variables, because they were dominated by components with different uncertainties. When using source-specific risks for risk-mitigation strategies, the focused toxic components, used toxic values, PM sizes and uncertainty are necessary to be considered.

Two 1D Anderson-Type Polyoxometalate-Based Metal-Organic Complexes as Bifunctional Heterogeneous Catalysts for CO2 Photoreduction and Sulfur Oxidation.

Sulfur oxides from the combustion of petrol and excessive emissions of carbon dioxide (CO2) are currently the main causes of environmental pollution. Considerable interest has been paid to solving the challenge, and catalytic reactions seem to be the desired choice. Due to the high density of Lewis acid active sites, polyoxometalates are considered to be the ideal choice for these catalytic reactions. Herein, two captivating polyoxometalate-based metal-organic complexes, formulated as [Co(H2O)2DABT]2[CrMo6(OH)5O19] ({Co-CrMo6}) and [Zn(H2O)2DABT]2[CrMo6(OH)5O19] ({Zn-CrMo6}) (DABT = 3,3'-diamino-5,5'-bis(1H-1,2,4-triazole)) were successfully obtained under hydrothermal conditions. The structural analysis demonstrates that {Co-CrMo6} and {Zn-CrMo6} are isostructural with two different transition metal (Co/Zn) ions based on quadridentate Anderson-type [CrMo6(OH)5O19]4- polyanions. A fan-shaped unit of {Co-CrMo6}/{Zn-CrMo6} is linked to generate a one-dimensional (1D) ladder-like structure. Intriguingly, benefitting from rich Co centers with a suitable energy band structure, {Co-CrMo6} displays better photocatalytic activity than {Zn-CrMo6} for converting CO2 into CO, endowing the CO formation of 1935.3 μmol g-1 h-1 with high selectivity. Meanwhile, {Co-CrMo6} also exhibits a satisfactory removal rate of 99% for oxidizing dibenzothiophene at 50 °C, which suggests that {Co-CrMo6} may be utilized as a potential dual functional material with immense prospects in photocatalytic CO2 reduction and sulfur oxidation for the first time.

Contrasting Effects of Air Pollution Assessment in two Areas of the Quito Metropolitan District, Ecuador

One of the main factors of air contamination within urban areas is burning gasoline by cars, light trucks and motorcycles. Gasoline burning liberates pollution gases such as Nitrogen dioxide, Sulfur dioxide, Carbon monoxide, benzene, besides others. Among these, Nitrogen dioxide (NOx) is the one that stands out for the people’s awareness of such contamination. We used the Hedonic Price Method (HPM) in order to determine people’s perception of air quality as a proxy and estimate the effect of gases on the housing market. We selected two areas of Quito Metropolitan District in order to evaluate contamination effects on properties. One with a higher concentration of gases located within the historic district of Quito. The other with better air quality called the Bellavista district. The results of three different models indicated that a reduction of 1 (µg/m3) of NOx would increase an average of 4.54% of the housing market value, which it represents 2,032,326.24 USD in value for sample properties. A decrease of 5 µg/m3 will increase in 22.7% of properties value.

Late Holocene human-environment interactions on the central California coast, USA, inferred from Morro Bay salt marsh sediments

Coastal salt marshes and estuaries provide valuable ecosystem services, yet are susceptible to alteration from human activities. Records of past environmental change in these ecosystems can elucidate relationships between human activities, such as land-use practices, and physical and ecological processes, such as sediment accretion and vegetation changes. To reconstruct the environmental history of one such site, we present inferences based on analysis of sediment cores (including magnetic susceptibility, loss-on-ignition, and pollen) from the Morro Bay salt marsh, located in California’s central coast in the USA. Chronologic control for the sediments was established using radiocarbon dates, a spike in lead (Pb) sourced from gasoline combustion exhaust, and the first identified occurrences of the non-native taxa Erodium cf. cicutarium (filaree) and Eucalyptus. We demonstrate that the Morro Bay watershed was significantly altered following Spanish settlement in the region. Environmental changes associated with livestock grazing and agriculture become evident in the data starting after 1772 CE, when the Mission San Luis Obispo de Tolosa was established nearby. The most prominent changes observed are an increase in the accumulation rate of terrigenous sediment, organic matter, and carbonates, as well as a reduction in arboreal taxa concomitant with increased abundances of shrubs, herbs, and grasses. The expansion of Salicornia (pickleweed) in the 19th century suggests the salt marsh expanded at this time due to increased sediment accumulation and a resulting increase in local elevation. The timing and character of changes recorded in the Morro Bay salt marsh sediments are similar to those documented across California in estuaries, marshes, lakes, and meadows, demonstrating the magnitude of the impacts of European settlement and associated land-use practices in this region.

Effects of Ethanol and Methanol on the Combustion Characteristics of Gasoline with the Revised Variation Disturbance Method.

This paper proposes a revised variation disturbance method to provide valuable information and reference for fuel design or optimization of internal combustion engines to realize the comprehensive and quantitative evaluation of the effects of blending agents on the combustion performance of primary fuels. In this method, methanol and ethanol are blended into gasoline to form six kinds of alcohol–gasoline (E10, E20, E30, M10, M20, and M30). Then, the ignition delay, adiabatic flame temperature, component concentration, fuel-burning rate, extinction strain rate, and CO emission of gasoline and alcohol–gasoline are studied by system simulation in a wide range of operating conditions. Based on the new variation disturbance method, the effects of methanol and ethanol on the combustion performance of gasoline are next analyzed globally and characterized quantitatively. The comprehensive results of ethanol and methanol on the gasoline’s combustion are visually presented. The method proposed in this paper is preliminarily validated based on the analysis of the microscopic mechanism of combustion. The results show that the blending of ethanol and methanol has positive effects on gasoline combustion, and ethanol can rapidly ignite the gasoline in a wide range of operating conditions and is superior to methanol in terms of fuel combustion, stability, and pollutant discharge. Based on the treatment of simulated values of six combustion characteristics selected in this paper and the calculations of the variation disturbance method, the total disturbance values of ethanol and methanol to gasoline combustion are obtained as 0.8493 and 0.2605, respectively. That is, ethanol has a more significant effect on improving the combustion performance of gasoline than methanol. In addition, based on the analysis results of the combustion, it is found that the blending of ethanol enlarges the reaction of notable components in gasoline. This finding also proves the effectiveness and validity of the scientific method utilized in this paper.

Testing sodium borohydride as a fuel additive in internal combustion gasoline engine

Additives are added to conventional fuels to ensure complete combustion of fuels, increase engine performance and reduce harmful emissions from vehicles. Hydrogen and oxygen-containing fuel additives added to fossil-based internal combustion engine fuels improve the properties of the fuels and reduce vehicle-related emissions. Evaluation of mixed fuels created by adding different types of alcohol and nano-sized additives to motor fuels as an alternative fuel in motor vehicles is among the most researched scientific studies recently. In this study, alcohol-gasoline fuels (E5, M5), NaBH4-alcohol-gasoline fuels (ES5, MS5), and pure gasoline were tested in a gasoline engine. Fuels used in engine tests; E5 fuel (5% by volume ethanol 95% gasoline blend), M5 fuel (5% by volume methanol 95% gasoline blend), ES5 fuel (5% by volume NaBH4-ethanol solution 95% gasoline blend), MS5 fuel (5% by volume NaBH4-methanol solution 95% gasoline mixture) and pure gasoline. In the experiments, brake thermal efficiency, engine torque, specific fuel consumption, and exhaust gas temperature were measured and compared with pure gasoline. Compared to gasoline, the exhaust gas temperatures of all blended fuels decreased. On the other hand, there was an increase in engine torque values, except for ES5 fuel. At the same time, there was an increase in both specific fuel consumption and brake thermal efficiency. When the CO and HC emission values of the blended fuels are compared with the gasoline fuel values, the highest reduction in CO emissions occurred in ES5 blended fuel with 65.53%, while the highest decrease in HC emission was realized in E5 fuel with 19.09%. On the other hand, when NOx and CO2 emissions of E5, M5, ES5, MS5 mixed fuels are compared with gasoline, NOx emissions are 12.63%, 28.37%, 19.65%, respectively; decreased by 36.03% but CO2 emissions increased by 8.51%, 30.46%, 34.48%, 25.95% respectively.

Effects of Driving Style on Energy Consumption and CO2 Emissions

The tractive force developed by energy consumption (EC) in a car engine produces its acceleration and sustains the motion against velocity dependent resistance forces. In internal combustion engines, fuel burning entails pollutant emissions (PE) released into the atmosphere. In vehicular traffic, EC and PE depend on the driving style. This paper assumed that the transition rules in a traffic cellular automata (TCA) represent a driving style, and its effect on EC and PE in TCA is studied. Extending empirical relationships, we proposed models to estimate EC and PE in TCA from the velocity and acceleration distributions, which we obtained by computer simulations for three well-known TCA. The Nagel-Schreckenberg (NS) and Fukui-Ishibashi (FI) models, and a variant (NS+FI) defined by combining the NS and FI rules, were considered. The FI driving style revealed EC and CO2 emission rates dependent on the stochastic delay (p) only for low vehicular densities. We also detected that the larger EC and CO2 emission rates were 45.4 kW and 26.7 g/s with no dependence on p. With NS and NS+FI driving styles, the larger energy consumption and CO2 emission rates occurred for small stochastic delays, 18.4 kW and 6.6 g/s and 61.1kW and 30.2 g/s for p = 0.2. On average, for NS, FI, and NS+FI models (p = 0.2), we obtained energy consumptions of 1.88, 2.60, and 2.76 MJ/km, fuel consumptions of 0.08, 0.12, and 0.13 L/km, and CO2 emissions of 0.158, 0.460, and 0.562 kgCO2/km. Our results agree with those (3.37 MJ/km and 0.235 kgCO2/km) of petrol combustion car engines at 10 km/L. This work may help in designing flow and driving style scenarios to optimize vehicular traffic EC and reduce PE.

Assessment of Polycyclic Aromatic Hydrocarbons and Heavy Metal Pollutants in Soil Around Semi Urban Petrol Stations and Automobile Mechanic WorkshopsAssessment of Polycyclic Aromatic Hydrocarbons and Heavy Metal Pollutants in Soil Around Semi Urban Petrol Stations and Automobile Mechanic Workshops

This study assessed the heavy metals and polycyclic aromatic hydrocarbons (PAHs) pollutant in soil around petrol filling stations and automobile mechanic workshops. Samples of soil were acquired from the depth range of 0–15 cm. Toxic heavy metals were analyzed with atomic absorption spectrophotometry. The PAHs were analyzed using phytochemical chromatographic analysis by the Soxhlet extraction method. The soil tested was weakly acidic (6.12–6.81). The trend of the heavy metals’ mean levels in soil followed the order: lead (Pb) > nickel (Ni) > vanadium (V) > cadmium (Cd). The mean levels of PAHs were in the order: 1,2-benzanthracene pyrene > anthracene > fluorene > benzo(b)fluoranthene > 1,1,2-benzopyrelene (BghiP) > naphthalene (Naph) > Dibenz(a, h)anthracene > 1, 2 benzanthracene > benzo(k)fluoranthene > phenanthrene > pyrene > xylene > acenapthylene. Pearson correlation and principal component analysis (PCA) revealed the heavy metals were generated from automobile exhaust and parent rocks. Soil pollution index and Numerov composite pollution index revealed that the soil is safe, clean, and unpolluted with heavy metals. The mean levels of heavy metals were below the European Union (2006) permissible values for uncontaminated soil. The PAH mean values were within permissible standards for unpolluted agricultural, forest, and residential soils. The diagnostic ratios of PAHs, supported by PCA, showed that PAHs in soil were produced by pyrogenic and internal combustion of gasoline and kerosene. This method of soil contamination assessment by heavy metals and PAHs is invaluable for pollution assessors in Nigeria and another area in the world.

Development and Validation of an EHN Mechanism for Fundamental and Applied Chemistry Studies

<div class="section abstract"><div class="htmlview paragraph">Autoignition enhancing additives have been used for years to enhance the ignition quality of diesel fuel, with 2-ethylhexyl nitrate (EHN) being the most common additive. EHN also enhances the autoignition reactivity of gasoline, which has advantages for some low-temperature combustion techniques, such as Sandia’s Low-Temperature Gasoline Combustion (LTGC) with Additive-Mixing Fuel Injection (AMFI). LTGC-AMFI is a new high-efficiency and low-emissions engine combustion process based on supplying a small, variable amount of EHN into the fuel for better engine operation and control. However, the mechanism by which EHN interacts with the fuel remains unclear. In this work, a chemical-kinetic mechanism for EHN was developed and implemented in a detailed mechanism for gasoline fuels. The combined mechanism was validated against shock-tube experiments with EHN-doped n-heptane and HCCI engine data for EHN-doped regular E10 gasoline. Simulations showed a very good match with experiments.</div><div class="htmlview paragraph">EHN chemistry fundamentals were also studied. Under LTGC-AMFI engine conditions, EHN generates NO<sub>2</sub>, formaldehyde and a combination of ~85% 3-heptyl and ~15% 1-butyl radical and butoxy diradical. Results show that the 3-heptyl and 1-butyl radicals are responsible for the autoignition-enhancing effect of EHN. Each mole of these radicals rapidly generates 2 moles of OH, which accelerate the low-temperature chemistry of the fuel, increasing its reactivity. The effects of the operating conditions on the effectiveness of EHN to increase the autoignition reactivity of the fuel were also studied. EHN’s effectiveness for increasing the autoignition reactivity is highest in the low-temperature regime, and it decreases as the temperature increases. EHN’s effectiveness to increase autoignition reactivity decreases with the combination of intake-pressure boost and EGR for typical engine operation. The effect of EHN on autoignition reactivity increases as equivalence ratio increases, enhancing the fuel’s φ-sensitivity. Therefore, with fuel stratification, EHN’s larger enhancement of autoignition reactivity for richer regions makes stratification techniques more effective.</div></div>

On the diversity of fossil and alternative gasoline combustion chemistry: A comparative flow reactor study

Recent progress in molecular combustion chemistry allows for detailed investigation of the intermediate species pool even for complex chemical fuel compositions, as occur for technical fuels. This study provides detailed investigation of a comprehensive set of complex alternative gasoline fuels obtained from laminar flow reactors equipped with molecular-beam sampling techniques for observation of the combustion intermediate species pool in homogeneous gas phase reactions. The combination of ionization techniques including double-imaging photoelectron photoion coincidence (i2PEPICO) spectroscopy enables deeper mechanistic insights into the underlying reaction network relevant to technical fuels. The selected fuels focus on contemporary automotive engine application as drop-in fuels compliant to European EN 228 specification for gasoline. Therefore, potential alternative gasoline blends containing oxygenated hydrocarbons as octane improvers obtainable from bio-technological production routes, e.g., ethanol, iso-butanol, methyl tert‑butyl ether (MTBE), and ethyl tert‑butyl ether (ETBE), as well as a Fischer-Tropsch surrogate were investigated. The fuel set is completed by two synthetic naphtha fractions obtained from Fischer-Tropsch and methanol-to-gasoline processes alongside with a fossil reference gasoline. In total, speciation data for 11 technical fuels from two atmospheric flow reactor setups are presented. Detailed main and intermediate species profiles are provided for slightly rich (ϕ = 1.2) and lean (ϕ = 0.8) conditions for intermediate to high temperatures. Complementary, the isomer distribution on different mass channels, like m/z = 78 u fulvene/benzene, of four gasolines was investigated. Experimental findings are analyzed in terms of the detailed fuel composition and literature findings for molecular combustion chemistry. Influences of oxygenated fuel components as well as composition of the hydrocarbon fractions are examined with a particular focus on the soot precursor chemistry. This dataset is available for validation of chemical kinetic mechanisms for realistic gasolines containing oxygenated hydrocarbons.

Occurrences, Sources, and Human Health Risk Assessments of Polycyclic Aromatic Hydrocarbons in Marine Organisms From Temperate Coastal Area

The pollution characteristics of 16 polycyclic aromatic hydrocarbons (PAHs) in marine organism species (6 species of fishes and 2 species of crustaceans) from the coastal area of the East China Sea were determined. The concentrations of 16 PAHs in the studied organisms ranged from 29.73 to 87.02 ng/g dw and 2- and 3-ring PAHs were the most abundant compounds in the aquatic organisms. The habitat, diet and predator-prey relationship have posed potential effects on the PAH accumulation in marine organisms. The source identification of PAHs was performed by using the molecular diagnostic ratios and principal component analysis (PCA). The results showed that the main sources of PAHs in the marine organisms were coal combustion, followed by mixture of gasoline combustion, oil combustion, crude oil spill and vehicle emissions. The incremental lifetime cancer risk of human via ingestion process of marine organisms in this sea area was also estimated and the assessment showed that it posed an acceptable but non-negligible risk to human health.

Pinacol hydrate as a novel thermal energy storage medium for electric vehicles

Movement towards the gradual replacement of gasoline combustion vehicles to electrical vehicles is occurring on a global scale. Heat management of lithium-ion batteries (LIB) is necessary for long-term operation and safety of the power sources of electrical vehicles. This research suggests pinacol hydrate as a phase change material (PCM) for use as an alternative cooling media for LIB. The pinacol hydrate crystallizes under atmospheric pressure and temperatures around 45 °C, which are compatible with LIB operating conditions. Its dissociation enthalpy can control the excessive heating of the battery. The equilibrium phase transition temperature of pinacol hydrate was reported about a decade ago, but its thermal storage capacity has not been reported yet and updated quantitative measurements are required. Hence, in this study the equilibrium temperatures and dissociation enthalpies are experimentally measured for pinacol aqueous solutions prepared with mass fractions between 0.40 and 0.85. The maximum thermal storage capacity is measured by differential scanning calorimetry to be 301.9 kJ/kg for mass fraction of 0.50 which is compatible with operating conditions of up to 45.6 °C. A minimization of reservoir tank mass by 35% of that needed for conventional technologies may be possible by using pinacol hydrate.

Benzo[ghi]perylene induces cellular dormancy signaling and endoplasmic reticulum stress in NL-20 human bronchial epithelial cells

Benzo[ghi]perylene (BghiP) is produced by the incomplete combustion of gasoline and it is a marker of high vehicular flow in big cities. Nowadays, it is known that BghiP functions as ligand for the aryl hydrocarbon receptor (AhR), which can cause several molecular responses. For this reason, the aim of the present study was to assess the in vitro effects of the exposure to BghiP, specifically, the induction of cellular dormancy and endoplasmic reticulum stress (ER stress) in NL-20 human cells. Our results proved that a 24 h exposure of BghiP, increased the expression of NR2F1 (p < 0.05). NR2F1 is the main activator of cell dormancy, therefore, we analyzed the expression of its target genes SOX9 and p27 showing an increase of the transcripts (p < 0.05), suggesting a pathway that could produce a cell cycle arrest. Interestingly, this effect was only observed with BghiP exposure, and not with a classic AhR ligand: benzo[a]pyrene. Moreover, in the presence of the AhR antagonist, CH223191, or when the expression of AhR was knock-down using dsiRNAs, the cellular dormancy signaling pathway was blocked. Morphological and ultrastructure analysis demonstrated that BghiP also induces ER stress, characterized by the dilated ER cisternae and the overexpression of PERK and CHOP genes (p < 0.05). Moreover, the halt of cell proliferation and the ER stress are both associated to the increase of pro-inflammatory cytokines (IL-6 and IL-8) and the cell survival in response to microenvironmental cues. These responses induced by BghiP on bronchial cells open new horizons on the research of other biological effects induced by environmental pollutants.

Quantum molecular modeling of oxazolidines as detergent-dispersant additives for gasoline: A valuable technological adviser

Patented detergent-dispersant (DD) additives based on oxazolidines [1] were quantum-mechanics modeled in order to get molecular-level insights into their functionality for removing and preventing formation of gum deposits in gasoline internal-combustion engines. The DDs are derived from polyalkenyl N-hydroxyalkyl succinimides whose polarities were modulated through a radical (R) substituent which can be either a phenol derivative (phenyl, 2-hydroxy-), pentyl or atomic hydrogen attached to the oxazolidine ring. We propose a mechanism for the performance of DDs consisting in the attraction of gum molecules by the DDs’ polar heads and their subsequent transference onto the DDs’ hydrophobic alkyl tails. Density-Functional-Theory (DFT) calculations of electrostatic properties and interaction energies support the above molecular mechanism, and furthermore make the prediction that the best performance is reached when R = atomic hydrogen, as it was found through experimental tests [1]. DFT also allowed to realize that gum agglomerates within gasoline because the attractive interaction among gum monomers is stronger than among gum and gasoline molecules due to the gum’s high polarity induced by the carbonyl and alkene functional groups. Likewise, these functional groups are responsible for gum to adhere firmly to oxidized metallic surfaces in contact with gasoline because they complete the octahedral coordination of the exposed superficial iron atoms, reaching at this manner the same strongest spin polarization that iron atoms have at the bulk crystalline oxidized metal. However, the oxazolidine-based DDs remove deposited gum since they adhere stronger to these surfaces than gum does because their polar heads have more bonding sites than gum, the DD having the radical hydrogen being easiest to be desorbed after gum removal avoiding so be burned by sticking to the metallic surface during gasoline combustion.