Gasoline Combustion Research Articles

WEAR OF FUNCTIONAL PAIRS OF A GASOLINE ENGINE COMBUSTION CHAMBER

Gasoline combustion engine is generally the most important part of a car. With this driving unit the car achieves the best ratio between its fuel utilization and weight. In order to comply with required parameters, such as performance, ecology and economy of combustion engines, their regular service inspections and associated maintenance operations must be followed. For testing the operability of these engines, especially for testing the wear of functional pairs of the combustion chamber, we use various methods. The paper deals with detection of wear of combustion engine functional pairs and with subsequent comparison of obtained values with the values declared by the manufacturer. The measurements were carried out on a Suzuki gasoline engine G13BA with a cubature of 1298 cm3 and a total mileage of 160,000 km.

Seasonality, sources apportionment, human health risks assessments, and potential implications on the atmospheric chemistry of polycyclic aromatic hydrocarbons in size-segregated aerosols from a Romanian metropolitan area.

Urbanization and industrialization are important transformations shaping the current statement of the society, enhancing significantly the combustion emissions which are threatening the global climate system, air quality, and human health. These emissions contain polycyclic aromatic hydrocarbons (PAHs) which are well known for their high toxicity. The present study is the first assessing the seasonal variation of 17 PAHs in size segregated fractions of atmospheric aerosol particles from a Romanian metropolitan area. In addition to sources apportionment and health risks, the potential role of PAHs on the atmospheric chemistry in the area was also addressed. Higher PAHs concentrations were determined in winter season, the highest values being quantified for benzo[b]fluoranthene, benzo[a]pyrene, and indeno[1,2,3-cd]pyrene. Each analyzed PAH exhibited a dominant peak in the accumulation mode (0.1-1.0 μm), with maxima at 381 nm. Gasoline combustion was identified as a significant contributor to the PAHs levels in the atmospheric aerosols from the area. Biomass-burning contributions were highlighted during the winter and autumn seasons. The positive matrix factorization (PMF) model apportioned four PAHs sources, as follows: vehicular (31%), mixed combustion (33%), biomass and wood burning (19%), and coal and natural gas combustion (18%) sources. Concentration-weighted trajectory (CWT) analysis method revealed clear contributions to PAHs abundances from local and regional air masses. Alveolar region of adults seems to have the highest susceptibility for PAHs deposition. Values exceeding acceptable limits for carcinogenic risk throughout the year are associated with benzo[a]pyrene, benzo[b]fluoranthene, indeno[1,2,3-cd]pyrene, benzo[a]anthracene etc. The present study can be considered as a reference in the region in order measures of mitigation and control for PAHs emission sources to be introduced.

The Environmental Impact of a High-Altitude Medical Research Expedition.

Joyce, Kelsey E., Catherine A. Campbell, Arthur R. Bradwell, Samuel J.E. Lucas, Christopher T. Lewis, Rebekah A.I. Lucas, and Mark Edsell. The environmental impact of a high-altitude medical research expedition. High Alt Med Biol. 00:00-00, 2024. Introduction: Scientists must begin examining the environmental cost(s) of their research. The purpose of this study was to evaluate a component of the environmental impact of a high-altitude medical research expedition by totaling the carbon dioxide (CO2) emissions calculated from as many direct and indirect sources as possible. Methods: Eighteen individuals flew from London to Bagdogra (via Delhi), and then drove onward to Lachung (via Gangtok) where they began their ascent on foot to 4,800 m (Kanchenjunga National Park, Sikkim). Several research experiments were conducted throughout the expedition, which required use of a laboratory centrifuge, solid CO2 (specimen storage), rechargeable laptop computers and battery-powered oximeters. International Civil Aviation Organization calculators estimated aviation CO2 production. Land emissions were calculated for Mahindra vehicles. Solid waste was weighed and CO2 emissions estimated for its incineration. Results: Total CO2 emissions equated to ∼16.7 tonnes from the following sources: air and land transportation of expedition team (87.3%); sublimation and transportation of solid CO2 (7.7%), waste incineration (0.58%), generator transportation and gasoline (12 l) combustion (0.48%), and battery transportation (3.3%). Conclusions: Air travel contributed the most to the overall environmental cost of the research expedition. Further investigation is required to contextualize these findings in relation to lab-based alternative(s).

Multisectoral Emission Impacts of Electric Vehicle Transition in China and India.

Transitioning to electric vehicles (EVs) is a central strategy for reducing carbon dioxide and air pollutant emissions. Although the emission impacts of reduced gasoline combustion and increased power generation are well recognized, the impacts of growing EV manufacturing activities remain understudied. Here, we focus on China and India, two of the fastest-growing EV markets. Compared to a 2030 baseline scenario, we find that national emissions of air pollutants could increase in certain high EV penetration scenarios as a result of the emission-intensive battery material production and manufacturing processes. Notably, national sulfur dioxide emissions could increase by 16-20% if all batteries have nickel- and cobalt-based cathodes and are produced domestically. Subnational regions that are abundant in battery-related minerals might emerge as future pollution hotspots. Our study thus highlights the importance of EV supply chain decisions and related manufacturing processes in understanding the environmental impacts of the EV transition.

A methodology to replicate LTGC engine conditions in a single-zone model and validate gasoline surrogate formulations versus experimental measurements

In this work, surrogate fuels for three premium-grade gasoline fuels were formulated and its autoignition behavior was validated, together with that of an existing surrogate for E10 regular gasoline, by comparison to experimental data measured in the Sandia Low-Temperature Gasoline Combustion research engine facility. Surrogate fuels have been previously designed by matching fuel properties such as octane number, fuel/air stoichiometric ratio and hydrogen/carbon ratio. However, similar octane rating can be obtained with several blends that will show different ignition characteristics. To avoid this issue, the surrogate fuels shown in this paper have been formulated by matching the main components of the fuel detailed hydrocarbon analysis. Validation of the surrogates was performed by replicating engine experiments run with the real fuel in a 0-D internal combustion engine reactor model with detailed chemistry. A fitted heat-loss model had to be implemented to properly replicate the experimental in-cylinder thermodynamic conditions, which invalidates the adiabatic assumption sometimes applied to engine simulations. Furthermore, minor species present in the EGR and residuals, such as CO and NOx, had to be taken into account to replicate the experimental low-temperature heat release (LTHR) trends. Therefore, accounting for heat losses and detailed in-cylinder composition are essential to accurately simulate the engine data. The bottom dead center temperature deviation required to obtain the same combustion timing as in the experiments was used as a metric to evaluate the accuracy of simulations. The surrogates gave good performance for the whole explored range, and replication of LTHR is a key factor in matching the experimental data. Chemical kinetic analyses showed that replication of LTHR is controlled by the ability of the surrogate to properly balance radical generation from low-temperature chain branching decomposition with radical consumption from stable species. Surrogate components that act as a sink of radicals tend to suppress the LTHR of the fuel, which may lead to large deviations between simulations and experiments. Especial attention should be paid to these fuel species when selecting the surrogate components.

Prenatal Exposure to Source-Specific Fine Particulate Matter and Autism Spectrum Disorder.

In this study, associations between prenatal exposure to fine particulate matter (PM2.5) from 9 sources and development of autism spectrum disorder (ASD) were assessed in a population-based retrospective pregnancy cohort in southern California. The cohort included 318,750 mother-child singleton pairs. ASD cases (N = 4559) were identified by ICD codes. Source-specific PM2.5 concentrations were estimated from a chemical transport model with a 4 × 4 km2 resolution and assigned to maternal pregnancy residential addresses. Cox proportional hazard models were used to estimate the hazard ratios (HR) of ASD development for each individual source. We also adjusted for total PM2.5 mass and in a separate model for all other sources simultaneously. Increased ASD risk was observed with on-road gasoline (HR [CI]: 1.18 [1.13, 1.24]), off-road gasoline (1.15 [1.12, 1.19]), off-road diesel (1.08 [1.05, 1.10]), food cooking (1.05 [1.02, 1.08]), aircraft (1.04 [1.01, 1.06]), and natural gas combustion (1.09 [1.06, 1.11]), each scaled to standard deviation increases in concentration. On-road gasoline and off-road gasoline were robust for other pollutant groups. PM2.5 emitted from different sources may have different impacts on ASD. The results also identify PM source mixtures for toxicological investigations that may provide evidence for future public health policies.

Low-Temperature Reforming Products coupling Spark Plug on Gasoline Compression Ignition and Combustion Characteristics under Low-Load Condition

Low-Temperature Reforming Products coupling Spark Plug on Gasoline Compression Ignition and Combustion Characteristics under Low-Load Condition

Characterization and health risk assessment of n-alkanes and PAHs in sediments from Shalateen (Halayeb Triangle), Egyptian Red Sea Coast

In this paper, the concentrations, origins, and carcinogenic potential of n-alkanes and polycyclic aromatic hydrocarbons (PAHs) collected from Shalateen sediments (Sh), Red Sea, Egypt were discussed. Individual n-alkanes has fluctuated from a minimum of 17.7 μg/g dw recorded for C-9 at Sh-54 to a maximum of 2.02 × 104 μg/g dw recorded for C-12 at Sh-B1. Total n-alkanes have fluctuated from 252–1.41 × 104 μg/g with a mean of 4.84 × 104 μg/g dw. C-12 had the highest average value, and C-19 had the lowest. The total ΣPAH concentrations in sediments from Shalateen as determined by gas chromatography-mass spectrometry/mass spectrometry (GC-MS/MS) ranged from 43.2 to 270 ng/g dw (averaging 95.2 ng/g dw). Carbon preference index (CPI) values were <1, consistent with the prevalence of even-C alkanes vs. the odd-C homologues. High molecular weight (HMW) PAHs were the most abundant substances affecting the collected samples. The cancer risk ranged from 2.25 × 10−5 to 4.78 × 10−2, indicating a moderate cancer risk associated with PAHs. The primary sources of PAHs in sediments included emissions from burning gasoline and diesel, biomass, and natural gas. The current study is considered one of the most important and unique with regard to the amounts and distributions of n-alkanes and PAHs in sediments along the coasts of Shalateen. It is the first baseline data documentation (GC MS/MS approach) of n-alkanes and PAHs in the Shalateen region.

Promotion of La2O3 on Pd/Al2O3 three-way catalyst for passive selective catalytic reduction operation

For three-way catalysts (TWC) applied in lean burn gasoline engines for passive selective catalytic reduction (pSCR) operation, besides the conversion efficiency of HC/CO/NO, the production of NH3 is also an important concern. In this work, La2O3 was introduced into the Pd/Al2O3 catalyst system, the influence on its TWC performance for pSCR operation was investigated, and the physicochemical properties were characterized by a range of techniques. The results reveal that the introduced La2O3 mainly interacts with Al2O3 by preferentially anchoring to the tetra-coordinated Al sites on the surface. When the catalyst is modified by appropriate amount of La2O3 (4 wt%), higher dispersion of Pd species, larger amount of Pd2+ and active oxygen species are achieved, which well contributes to improved low-temperature reduction ability and NH3 desorption property of the catalyst. As a consequence, excellent catalytic conversions of HC/CO/NO are obtained, and meanwhile, higher concentration of NH3 is generated, making the modified catalyst more promising for pSCR operation.

RESEARCH OF THE COMBUSTION PARAMETERS OF GASOLINE WITH ADDITIONAL HYDROGEN IN A SPARK-IGNITION ENGINE IN EXTERNAL SPEED CHARACTERISTIC MODES

The directions of development and improvement of road transport around the world are inextricably linked to the desire to reduce the use of cars “on traditional fuels” due to limited oil and environmental safety of mankind. Since the modes of external speed characteristic are the most typical for the operation of cars in cities, the study of environmental performance of engines in these modes is an urgent task. Therefore, finding ways to reduce carbon dioxide emissions from automobile engines at high-speed modes is an urgent task. The rapid growth in the number of cars with internal combustion engines and the inevitable decline in world oil reserves necessitate the development and implementation of energy-saving technologies and the use of alternative fuels. Research aimed at finding ways to improve the fuel efficiency and environmental performance of automotive engines is relevant. One of the promising areas is the influence on the combustion process in gasoline engines by using additives of alternative fuels, which include hydrogen. The presented study of the parameters of combustion of gasoline with hydrogen additive in a spark ignition engine at external speed characteristics is a comprehensive analysis of the combustion process of a gasoline-hydrogen mixture and determination of its effect on the concentration of carbon dioxide in exhaust gases by developing a mathematical model that takes into account the composition of the mixture components and features of the combustion process, allows for sufficiently accurate calculation of the operating process of an engine with hydrogen additive at ψ ≤ 10%, its identification by the results of experiments. In the course of the study, dependencies were developed to determine the combustion parameters of the Wiebe model, taking into account the addition of hydrogen to gasoline in the modes of external speed characteristics, and the effect of hydrogen addition on the concentration of CO2 in exhaust gases was analyzed. It is shown that with an increase in the hydrogen additive to 10% by mass fraction to gasoline, there is a decrease in CO2 emissions to almost 30% in the external speed characteristic modes, which corresponds to modern environmental standards for gasoline internal combustion engines.

The Influence of Fuel Type on MotorcycleVehicle Exhaust Emission Tests

A vehicle engine's performance can be determined through exhaust emission tests. Exhaust emissions contain air pollutants that result from incomplete fuel combustion in the vehicle's combustion chamber. This is usually due to improper oxygen and air mixture conditions. Gasoline (CxHy) burns and reacts with oxygen (O2) to produce carbon dioxide (CO2), water (H2O), as well as non-toxic gases like nitrogen (N2) and water vapor (H2O (g)). However, it also generates toxic gases such as CO, HC, and Nitrogen Oxides (NOx). Motorcycle exhaust emission tests are commonly conducted using a gas analyzer. In this study, a gas analyser was used to measure the amount of CO, CO2, HC, O2, and NOx emitted from motorcycle exhausts. The tests were carried out using the Vario 160 ABS motorcycle with different types of fuel: RON 92 (S), RON 92 (P), RON 90, RON 98, and RON 92 (R). The data was collected at idle, as well as at 1600 rpm, 1800 rpm, and 2000 rpm. Three measurements were taken for each variable, and the average was calculated. The results showed that RON 98 fuel resulted in better combustion compared to RON 90 and RON 92, as indicated by the CO2 content at idle, which was 13.95%. Additionally, when the motorcycle's engine was throttled, RON 98 fuel did not produce any NOx. The study also revealed that RON 92 (S) fuel led to better combustion compared to both of RON 92 (P) and RON 92 (R), as evidenced by the CO content of 0.05%, CO2 content of 13.63%, HC content of 204 ppm, O2 content of 0.03%, and NOx content of 4 ppm at idle.

Effects of several typical plastic combustion residues on gasoline

Abstract In order to solve the interference caused by polymer materials on gasoline accelerants in arson cases, the characteristics of residues after combustion of some typical plastics are studied. Comparing it to the combustion residue of gasoline, we discussed the interference in gasoline detection. The results show that the combustion products of these plastics mainly interfere with the alkanes and aromatic hydrocarbons in gasoline. Polyethylene, polystyrene, and polyvinyl chloride mainly produce C9-C16 branched-chain and straight-chain alkanes. Polystyrene and ABS resin generated C5 and C6 alkanes, also generated C1-benzene, C2 - benzene, and styrene. It mainly affects the identification of aromatic hydrocarbons in gasoline combustion residues. Understanding the types and characteristics of products in the combustion residues of these plastics can provide powerful evidence for fire investigators and criminal technicians in physical evidence identification.

Methanol, the ICE Green Maker

AbstractGreen methanol is a renewable fuel with great advantages when used in a spark ignition combustion process. Methanol has a comparatively high enthalpy of vaporization, leading to lower combustion temperatures as compared to gasoline combustion, and, hence, lower wall heat losses as well as a reduced tendency to pre‐ignition. Therefore, a brake efficiency of more than 40 % (this is comparable to diesel engines!) and furthermore minimal emissions, even at cold start, are possible. The serial combination with an electric powertrain provides a disconnection of the load demand of the powertrain and the operating point of the combustion engine. In this case, a high volumetric and gravimetric power density, easy energy storage and proven infrastructure of fuel distribution are combined with electric driving, high efficiencies, minimal emissions, and a closed carbon cycle for the energy provision.

Interactions between phenanthrene exposure and historical chemical stress: Implications for fitness and ecological resilience of the sentinel species Daphnia magna

Polycyclic aromatic hydrocarbons (PAHs) arise from incomplete combustion of oil, coal, and gasoline, with lipophilic properties facilitating their widespread distribution and persistence. Due to their biochemical attributes, PAHs can accumulate in animal tissues, potentially causing mutagenic and carcinogenic effects. Since the industrial revolution, PAH concentrations in the environment have risen, with lakes showing levels from 0.159 to 33,090 μg/kg sediment. Despite acute toxicity studies showing adverse effects on freshwater organisms, the long-term impacts and synergistic interactions with other pollutants remain largely unexplored.This study investigates the impact of phenanthrene (PHE), a prominent PAH found in aquatic environments, on Daphnia magna, a species of significant ecological importance in freshwater ecosystems globally, being both a sentinel species for chemical pollution and a keystone organism in freshwater aquatic ecosystems. Leveraging the dormancy of D. magna, which spans decades or even centuries, we exposed strains with diverse histories of chemical contaminant exposure to environmentally relevant concentrations of PHE. Initially, acute exposure experiments were conducted in accordance with OECD guidelines across 16 Daphnia strains, revealing substantial variation in acute toxic responses, with strains naïve to chemical pollutants showing the lowest toxicity. Utilizing the median effect concentration EC10 derived from acute exposures, we assessed the impacts of chronic PHE exposure on life history traits and ecological endpoints of the 16 strains. To elucidate how historical exposure to other environmental stressors may modulate the toxicity of PHE, temporal populations of D. magna resurrected from a lake with a well-documented century-spanning history of environmental impact were utilized. Our findings demonstrate that PHE exposure induces developmental failure, delays sexual maturation, and reduces adult size in Daphnia. Populations of Daphnia historically exposed to chemical stress exhibited significantly greater fitness impacts compared to naïve populations. This study provides crucial insights into the augmented effects of PAHs interacting with other environmental stressors.

Influence of Ambient Pressure on the Jet-Ignition Combustion Performance and Flame Propagation Characteristics of Gasoline in a Constant Volume Combustion Chamber

Based on a constant volume combustion chamber, the initial ambient pressure effect on gasoline combustion performance and flame propagation of the active and passive pre-chamber ignition systems were studied. Compared with the passive pre-chamber, the active pre-chamber can significantly expand the lean combustion limit from 1.2 to 1.5, enhance the ignition and combustion performance, and speed up the combustion of the main combustion chamber. At slightly lean combustion conditions, the heat release performance has a positive correlation with the initial ambient pressure. As the premixed λ increases, the heat release performance and the initial ambient pressure begin to become negatively correlated. Ignition delay can be decreased by approximately 50% at an initial pressure of 0.75 MPa, premixed lambda of 1.2 with APC compared with PPC. The high ambient pressure (1.0 MPa) in the constant volume chamber greatly reduces the mixture entrainment ability of the jet flame at lean combustion conditions, thereby reducing the combustion speed and peak heat release rate.

Seasonal and height dynamics of volatile organic compounds in rubber plantation: Impacts on ozone and secondary organic aerosol formation

Rubber trees emit a range of volatile organic compounds (VOCs), including isoprene, monoterpenes, and sesquiterpenes, as part of their natural metabolism. These VOCs can significantly influence air quality through photochemical reactions that produce ozone and secondary organic aerosols (SOAs). This study examines the impact of VOCs detected in a rubber tree plantation in Northeastern Thailand on air quality, highlighting their role in atmospheric reactions that lead to the formation of ozone and SOAs. VOCs were collected at varying heights and seasons using Tenax-TA tubes paired with an atmospheric sampler pump and identified by gas chromatography–mass spectrometry. In total, 100 VOCs were identified, including alkanes, alkenes, terpenes, aromatics, and oxygenated VOCs. Principal Coordinate Analysis (PCoA) revealed distinct seasonal VOC profiles, with hydrocarbons, peaking in summer and terpenes in the rainy season. The Linear Mixed-Effects (LME) model indicates that VOC concentrations are more influenced by seasonal changes than by sampling heights. Secondary organic aerosol potential (SOAP) and ozone formation potential (OFP) of selected VOC species were also determined. The total SOAP ranged from 67.24 μg/m3 in summer to 17.87 μg/m3 in winter, while the total OFP ranged from 377.87 μg/m3 in summer to 139.39 μg/m3 in winter. Additionally, positive matrix factorization (PMF) analysis identified four main VOC sources: gasoline combustion (18.3 %), microbial activity (38.6 %), monoterpene emissions during latex production (15.0 %), and industrial sources (28.1 %). These findings provide essential information for managing air pollution in rubber tree plantations. By adopting focused air quality management strategies, plantation operators can mitigate the adverse effects of VOCs, promoting a healthier and more sustainable future.

Unveiling the Potential of Hydrogen in a Downsized Gasoline Direct Injection Engine Performance and Emissions Experimental Study

&lt;div&gt;The transportation sector’s growing focus on addressing environmental and sustainable energy concerns has led to a pursuit of the decarbonization path. In this context, hydrogen emerges as a promising zero-carbon fuel. The ability of hydrogen fuel to provide reliable performance while reducing environmental impact makes it crucial in the quest for net zero targets. This study compares gasoline and hydrogen combustion in a single-cylinder boosted direct injection (DI) spark ignition engine under various operating conditions. Initially, the engine was run over a wide range of lambda values to determine the optimal operating point for hydrogen and demonstrate lean hydrogen combustion’s benefits over gasoline combustion.&lt;/div&gt; &lt;div&gt;Furthermore, a load sweep test was conducted at 2000 rpm, and the performance and emission results were compared between gasoline and optimized hydrogen combustion. An in-depth analysis was conducted by varying fuel injection time and pressure. This enabled us to explore the effects of these variables on the fuel’s performance and emissions, providing valuable insights for further optimization.&lt;/div&gt; &lt;div&gt;The key findings of this study are significant. They note that hydrogen fuel allows the engine to operate under lean conditions with stable combustion up to 3.8 lambda. Lean combustion produces higher engine thermal efficiency, low cyclic variability, and near-zero NO&lt;sub&gt;x&lt;/sub&gt; emissions. According to the study, hydrogen combustion produces zero emissions of hydrocarbons (HC), carbon monoxide (CO), and carbon dioxide (CO&lt;sub&gt;2&lt;/sub&gt;) under a wide range of operating conditions, making it a clean and environmentally friendly fuel source. During low loading, exhaust hydrogen slip is less than 1000 ppm. This slip drops below 500 ppm as the load increases. Finally, the study proved that hydrogen is more stable than gasoline at a stoichiometric level. This suggests that hydrogen could replace gasoline in some applications, which has major implications for alternative energy.&lt;/div&gt;

Comparison of the effects of gasoline burn and chromic acid burn on different internal organs and immune functions in rats.

Burn as physical injury ranks as the fourth most prevalent trauma across the world. In this study, we aimed to compare the impact of gasoline burn and chromic acid burn on the internal organs and immune functions in rats. The results showed that the levels of methemoglobin (MHb) to total hemoglobin (Hb) as well as the Cr6+ content showed significant elevation in the chromic acid burn group relative to the gasoline burn group. HE staining was used to evaluate the histological changes in the injured tissues as well as the tissues excised from internal organs. We found that chromic acid burn-induced more severe damage to rat tissues. Gasoline burn showed no significant impact on the intestinal tissues of rats, while the chromic acid burn-induced increased cell death in rat intestines. Moreover, the results of HE staining also revealed that gasoline burn and chromic acid burn showed no evident impact on rat hearts. Gasoline burn also showed no significant effects on the liver, lungs and kidneys of rats, while the chromic acid burn caused injuries to such internal organs in comparison with the control and gasoline burn groups. In addition, the MPO activity was higher in the liver, intestine, lungs and kidneys of rats with chromic acid burn. Furthermore, the expression of inflammation response cytokines was examined in the serum of rats. The results demonstrated that the levels of IL-6, IL-1β and TNF-α showed a significant increase in both the gasoline burn and chromic acid burn groups of rats relative to the control, and the levels were higher in the chromic acid burn group in comparison with the gasoline burn group. In conclusion, the chromic acid burn-induced more severe organ injury, inflammation and immune response compared with the gasoline burn, which may provide reference data for the clinical treatment of patients with different burn injuries.

Practical low-temperature gasoline combustion for very high efficiency off-road, medium- and heavy-duty engines

Low-temperature gasoline combustion (LTGC) with additive-mixing fuel injection (AMFI) is a new combustion strategy that has been demonstrated to deliver 9%–25% better brake thermal efficiency than similar-sized market-leading diesel engines over the operating map. Moreover, the LTGC-AMFI engine shows near-zero smoke, and NOx emissions are 4–100 times lower than those of a diesel, sufficiently low that no aftertreatment, or only passive NOx aftertreatment, would be sufficient (diesel exhaust fluid is not required). LTGC-AMFI combustion is based on kinetically controlled compression ignition of a dilute charge with a variable amount of low-to-moderate fuel stratification. Fast combustion control is provided by adding minute amounts of an ignition-enhancing additive into the fuel each engine cycle to control its reactivity. This strategy was used to operate a medium-duty (MD) LTGC-AMFI engine at loads from idle to 16.3 bar BMEP and speeds from 600 to 2400 rpm with regular E10 gasoline, which covers nearly the entire operating map of a typical MD engine. Turbine-out temperatures were sufficient for an oxidation catalyst to control hydrocarbon and CO emissions. Autonomie simulations over the GEM ARB Transient and the GEM 55 mph Cruise driving cycles for class-6 trucks using this technology showed fuel economies of 8.1 and 11.4 mpg-gasoline-equivalent, respectively, corresponding to 18.6% and 13.4% improvements over a similar-size diesel engine. Engine-out NOx emissions were 0.024 and 0.01 g/bhp-h, respectively, well below current U.S. emission standards. These results show that switching from diesel to LTGC-AMFI engines would greatly reduce greenhouse gas (GHG) emissions for off-road, MD and HD applications, which will continue to rely on combustion engines because electrification is not practical in the foreseeable future. With their reduced fuel consumption, the lower cost of gasoline compared to diesel fuel, and much lower aftertreatment costs, LTGC-AMFI engines also offer a significantly lower total cost of ownership.

Exposure to outdoor ambient air toxics and risk of breast cancer: The multiethnic cohort

BackgroundA growing literature has reported associations between traffic-related air pollution and breast cancer, however there are fewer investigations into specific ambient agents and any putative risk of breast cancer development, particularly studies occurring in populations residing in higher pollution areas such as Los Angeles. ObjectivesTo estimate breast cancer risks related to ambient air toxics exposure at residential addresses. MethodsWe examined the relationships between ambient air toxics and breast cancer risk in the Multiethnic Cohort among 48,665 California female participants followed for cancer from 2003 through 2013. We obtained exposure data on chemicals acting as endocrine disruptors or mammary gland carcinogens from the National-Scale Air Toxics Assessment. Cox proportional hazards models were used to estimate breast cancer risk per one interquartile range (IQR) increase in air toxics exposure lagged by 5-years. Stratified analyses were conducted by race, ethnicity, and hormone receptor types. ResultsAmong all women, increased risks of invasive breast cancer were observed with toxicants related to industries [1,1,2,2-tetrachloroethane (hazard ratio [HR] = 4.22, 95% confidence interval [95% CI] 3.18–5.60), ethylene dichloride (HR = 2.81, 95% CI 2.20–3.59), and vinyl chloride (HR = 2.27, 95% CI 1.81, 2.85); these 3 agents were correlated (r2 = 0.45–0.77)]. Agents related to gasoline production or combustion were related to increased breast cancer risk [benzene (HR = 1.32, 95% CI 1.24, 1.41), ethylbenzene (HR = 1.20, 95% CI 1.13–1.28), toluene (HR = 1.29, 95% CI 1.20–1.38), naphthalene (HR = 1.11, 95% CI 1.02–2.22), acrolein (HR = 2.26, 95% CI 1.92, 2.65)]. Higher hazard ratios were observed in African Americans and Whites compared to other racial and ethnic groups (p-heterogeneity <0.05 for traffic-related air toxics, acrolein, and vinyl acetate). ConclusionsOur findings suggest that specific toxic air pollutants may be associated with increase breast cancer risk.