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Vehicle technology development and upcoming particle emission limits have increased the need for detailed analyses of particle emissions of vehicles using gasoline direct injection (GDI) techniques. In this paper the particle emission characteristics of modern GDI passenger cars were studied in a laboratory and on the road, with the focus on exhaust particle number emissions, size distributions, volatility and morphology. Both during acceleration and steady conditions the number size distribution of nonvolatile exhaust particles consisted of two modes, one with mean particle size below 30 nm and the other with mean particle size approximately 70 nm. Results indicate that both of these particles modes consisted of soot but with different morphologies. Both in laboratory and on the road, significant emissions of exhaust particles were observed also during decelerations conducted by engine braking. These particles are most likely originating from lubricant oil ash components. The semivolatile nucleation particles were observed in the laboratory experiments at high engine load conditions. Thus, in general, the study indicates that a modern gasoline vehicle can emit four distinctive types of exhaust particles. The differences in particle characteristics and formation should be taken into account in the development of emission control strategies and technologies and, on the other hand, in the assessment of the impact of particle emissions on environment and human health.

Diesel exhaust gaseous sulphuric acid (GSA) concentrations and particle size distributions, concentrations, and volatility were studied at four driving conditions with a heavy duty diesel engine equipped with oxidative exhaust after-treatment. Low sulfur fuel and lubricant oil were used in the study. The concentration of the exhaust GSA was observed to vary depending on the engine driving history and load. The GSA affected the volatile particle fraction at high engine loads; higher GSA mole fraction was followed by an increase in volatile nucleation particle concentration and size as well as increase of size of particles possessing nonvolatile core. The GSA did not affect the number of nonvolatile particles. At low and medium loads, the exhaust GSA concentration was low and any GSA driven changes in particle population were not observed. Results show that during the exhaust cooling and dilution processes, besides critical in volatile nucleation particle formation, GSA can change the characteristics of all nucleation mode particles. Results show the dual nature of the nucleation mode particles so that the nucleation mode can include simultaneously volatile and nonvolatile particles, and fulfill the previous results for the nucleation mode formation, especially related to the role of GSA in formation processes.

Fully paraffinic diesel fuel produced from hydrotreated vegetable oils (HVOs) is one alternative to increase the share of renewable energy in the transport sector. HVO fuel has also been shown to reduce exhaust emissions but, as the fuel contains no oxygen, even higher emissions reductions are possible by blending the HVO fuel with suitable oxygenate. From a large number of oxygenates, di-n-pentyl ether (DNPE) was chosen due to its favourable fuel properties (e.g. high cetane number and good solubility to diesel). In this paper, it was studied how fuel blend containing 2 wt.% oxygen (80 wt.% HVO and 20 wt.% DNPE) affects particulate and NOx emissions of a single-cylinder research engine. It was observed that the blend reduced emitted particulate mass 25-30% depending on load while the NOx emissions was changed under 5%. Thus, PM and NOx can possibly be both reduced e.g. by utilising EGR. In addition to emission reductions, the effects of the blend on the hygroscopic properties of produced exhaust particles were studied using a hygroscopic tandem differential mobility analyzer (HTDMA). The addition of oxygen into fuel led to a small increase in the hygroscopicity of exhaust particles.

The effect of intake valve closure (IVC) timing by utilizing Miller cycle and start of injection (SOI) on particulate matter (PM), particle number and nitrogen oxide (NOx) emissions was studied with a hydrotreated vegetable oil (HVO)-fueled nonroad diesel engine. HVO-fueled engine emissions, including aldehyde and polyaromatic hydrocarbon (PAH) emissions, were also compared with those emitted with fossil EN590 diesel fuel. At the engine standard settings, particle number and NOx emissions decreased at all the studied load points (50%, 75%, and 100%) when the fuel was changed from EN590 to HVO. Adjusting IVC timing enabled a substantial decrease in NOx emission and combined with SOI timing adjustment somewhat smaller decrease in both NOx and particle emissions at IVC -50 and -70 degrees CA points. The HVO fuel decreased PAH emissions mainly due to the absence of aromatics. Aldehyde emissions were lower with the HVO fuel with medium (50%) load. At higher loads (75% and 100%), aldehyde emissions were slightly higher with the HVO fuel. However, the aldehyde emission levels were quite low, so no clear conclusions on the effect of fuel can be made. Overall, the study indicates that paraffinic HVO fuels are suitable for emission reduction with valve and injection timing adjustment and thus provide possibilities for engine manufacturers to meet the strictening emission limits.

Hydrotreated vegetable oil (HVO) diesel fuel is a promising biofuel candidate that can complement or substitute traditional diesel fuel in engines. It has been already reported that by changing the fuel from conventional EN590 diesel to HVO decreases exhaust emissions. However, as the fuels have certain chemical and physical differences, it is clear that the full advantage of HVO cannot be realized unless the engine is optimized for the new fuel. In this article, we studied how much exhaust emissions can be reduced by adjusting engine parameters for HVO. The results indicate that, with all the studied loads (50%, 75%, and 100%), particulate mass and NOx can both be reduced over 25% by engine parameter adjustments. Further, the emission reduction was even higher when the target for adjusting engine parameters was to exclusively reduce either particulates or NOx. In addition to particulate mass, different indicators of particulate emissions were also compared. These indicators included filter smoke number (FSN), total particle number, total particle surface area, and geometric mean diameter of the emitted particle size distribution. As a result of this comparison, a linear correlation between FSN and total particulate surface area at low FSN region was found.

We have studied the effect of three different fuels (fossil diesel fuel (EN590); rapeseed methyl ester (RME); and synthetic gas-to-liquid (GTL)) on heavy-duty diesel engine emissions. Our main focus was on nanoparticle emissions of the engine. Our results show that the particle emissions from a modern diesel engine run with EN590, GTL, or RME consisted of two partly nonvolatile modes that were clearly separated in particle size. The concentration and geometric mean diameter of nonvolatile nucleation mode cores measured with RME were substantially greater than with the other fuels. The soot particle concentration and soot particle size were lowest with RME. With EN590 and GTL, a similar engine load dependence of the nonvolatile nucleation mode particle size and concentration imply a similar formation mechanism of the particles. For RME, the nonvolatile core particle size was larger and the concentration dependence on engine load was clearly different from that of EN590 and GTL. This indicates that the formation mechanism of the core particles is different for RME. This can be explained by differences in the fuel characteristics.

Particle emissions of modern diesel engines are of a particular interest because of their negative health effects. The special interest is in nanosized solid particles. The effect of an open channel filter on particle emissions of a modern heavy-duty diesel engine (MAN D2066 LF31, model year 2006) was studied. Here, the authors show that the open channel filter made from metal screen efficiently reduced the number of the smallest particles and, notably, the number and mass concentration of soot particles. The filter used in this study reached 78% particle mass reduction over the European Steady Cycle. Considering the size-segregated number concentration reduction, the collection efficiency was over 95% for particles smaller than 10 nm. The diffusion is the dominant collection mechanism in small particle sizes, thus the collection efficiency decreased as particle size increased, attaining 50% at 100 nm. The overall particle number reduction was 66-99%, and for accumulation-mode particles the number concentration reduction was 62-69%, both depending on the engine load.

Particle emissions from a modern turbocharged gasoline direct injection passenger car equipped with a three-way catalyst and an exhaust gas recirculation system were studied while the vehicle was running on low-sulfur gasoline and, consecutively, with five different lubrication oils. Exhaust particle number concentration, size distribution, and volatility were determined both at laboratory and on-road conditions. The results indicated that the choice of lubricant affected particle emissions both during the cold start and warm driving cycles. However, the contribution of engine oil depended on driving conditions being higher during acceleration and steady state driving than during deceleration. The highest emission factors were found with two oils that had the highest metal content. The results indicate that a 10% decrease in the Zn content of engine oils is linked with an 11-13% decrease to the nonvolatile particle number emissions in steady driving conditions and a 5% decrease over the New European Driving Cycle. The effect of lubricant on volatile particles was even higher, on the order of 20%.

This study has investigated the potential of immersion coating calcium containing pellet cores first with pectin, and then with two different cross-linkers, calcium or chitosan. The interaction between pectin and calcium, and between pectin and chitosan, are believed to slow down the drug release, and thereby, the coated pellets might possibly be used for colon specific drug delivery. Both the calcium coated pellets and the chitosan coated pellets had a reduced drug release compared to uncoated pellets in 0.1 M HCl (1 h) and phosphate buffer pH 6.8 (4 h). The most successful combination had a drug release of only 17% during the entire test period in comparison to the uncoated pellets that had a drug release of 80%. When chitosan was used as a cross-linker, a higher reduction in drug release was obtained than by using calcium as the cross-linker. For the pellets coated with pectin in combination with chitosan, the type of pectin with a degree of methoxylation (DM) of 35 was superior to the pectin type with DM 17. The drug release was further slowed down by choosing a type of chitosan with a high degree of deacetylation (Dda) 89% and by coating at low concentrations (0.1%) in the immersion solution.

Over the past decade significant research and development activities have been invested in alternative fuels in order to reduce our dependency on fossil fuel sources and reduce CO2 and local emissions from traffic. One result of these R&D efforts is paraffinic diesel fuels, which can be used with existing vehicle fleets and infrastructures. Paraffinic diesels also have other benefits compared to conventional diesels, for example a very high cetane number and the lack of sulfur and aromatic compounds. These characteristics are beneficial in terms of exhaust gas emissions, something which has been demonstrated in numerous studies. The objective of this study was to develop low-emission combustion technologies for paraffinic renewable diesel in a compression ignition engine, and to study the possible benefits of oxygenated paraffinic diesel. Hydrotreated vegetable oil (HVO), which is a commercial example of paraffinic, renewable diesel, was used with and without oxygenate in comparison with conventional diesel. Exhaust emissions were measured in three steady state conditions. The adjusted engine parameters, such as inlet valve closure and injection timing, injection pressure and amount of exhaust gas recirculation (EGR) were optimized for HVO. The results demonstrate that significant reductions of particulate matter (48-61%), polyaromatic hydrocarbon (75-87%) and NOx (31-54%) emissions can be achieved simultaneously by using HVO with adjusted engine parameters.

To mitigate the diesel particle pollution problem, diesel vehicles are fitted with modern exhaust after-treatment systems (ATS), which efficiently remove engine-generated primary particles (soot and ash) and gaseous hydrocarbons. Unfortunately, ATS can promote formation of low-vapor-pressure gases, which may undergo nucleation and condensation leading to formation of nucleation particles (NUP). The chemical nature and formation mechanism of these particles are only poorly explored. Using a novel mass spectrometric method, online measurements of low-vapor-pressure gases were performed for exhaust of a modern heavy-duty diesel engine operated with modern ATS and combusting low and ultralow sulfur fuels and also biofuel. It was observed that the gaseous sulfuric acid (GSA) concentration varied strongly, although engine operation was stable. However, the exhaust GSA was observed to be affected by fuel sulfur level, exhaust after-treatment, and driving conditions. Significant GSA concentrations were measured also when biofuel was used, indicating that GSA can be originated also from lubricant oil sulfur. Furthermore, accompanying NUP measurements and NUP model simulations were performed. We found that the exhaust GSA promotes NUP formation, but also organic (acidic) precursor gases can have a role. The model results indicate that that the measured GSA concentration alone is not high enough to grow the particles to the detected sizes.

Under on-road driving conditions, the engine load and speed and the cooling effect of ambient air may affect the functioning of exhaust aftertreatment devices. In this paper, we studied the effects of these parameters on the functioning of the combination of a Diesel Oxidation Catalyst and a Particle Oxidation Catalyst (DOC+POC). In the engine tests, the engine load and speed were observed to affect the nonvolatile particle reduction efficiency curve of the DOC+POC; while the nonvolatile core particle (Dp < 15 nm) reduction was high (97-99%) in all the engine test modes, the reduction of soot varied from 57% at low load to 70% at high load. Because the change in engine load and speed affected both the exhaust temperature and flow velocity, the effects of these parameters were measured separately in an aerosol laboratory. Results indicated that compared to the exhaust temperature, the exhaust flow velocity had a more significant role from the viewpoint of the nonvolatile particle reduction efficiency of the DOC+POC system. At three engine test modes, the external cooling did not affect the particle reduction of the DOC+POC. Instead, in one case (low engine load, low engine speed) the external cooling affected the particle reduction. However, this observation cannot be explained by thermophoretic forces.

At present, most of the neurotoxicological analyses are based on in vitro and in vivo models utilizing animal cells or animal models. In addition, the used in vitro models are mostly based on molecular biological end-point analyses. Thus, for neurotoxicological screening, human cell-based analysis platforms in which the functional neuronal networks responses for various neurotoxicants can be also detected real-time are highly needed. Microelectrode array (MEA) is a method which enables the measurement of functional activity of neuronal cell networks in vitro for long periods of time. Here, we utilize MEA to study the neurotoxicity of methyl mercury chloride (MeHgCl, concentrations 0.5-500 nM) to human embryonic stem cell (hESC)-derived neuronal cell networks exhibiting spontaneous electrical activity. The neuronal cell cultures were matured on MEAs into networks expressing spontaneous spike train-like activity before exposing the cells to MeHgCl for 72 hours. MEA measurements were performed acutely and 24, 48, and 72 hours after the onset of the exposure. Finally, exposed cells were analyzed with traditional molecular biological methods for cell proliferation, cell survival, and gene and protein expression. Our results show that 500 nM MeHgCl decreases the electrical signaling and alters the pharmacologic response of hESC-derived neuronal networks in delayed manner whereas effects can not be detected with qRT-PCR, immunostainings, or proliferation measurements. Thus, we conclude that human cell-based MEA-platform is a sensitive online method for neurotoxicological screening.

Sulfur driven diesel exhaust nucleation particle formation processes were studied in an aerosol laboratory, on engine dynamometers, and on the road. All test engines were equipped with a combination of a diesel oxidation catalyst (DOC) and a partial diesel particulate filter (pDPF). At steady operating conditions, the formation of semivolatile nucleation particles directly depended on SO2 conversion in the catalyst. The nucleation particle emission was most significant after a rapid increase in engine load and exhaust gas temperature. Results indicate that the nucleation particle formation at transient driving conditions does not require compounds such as hydrocarbons or sulfated hydrocarbons, however, it cannot be explained only by the nucleation of sulfuric acid. A real-world exhaust study with a heavy duty diesel truck showed that the nucleation particle formation occurs even with ultralow sulfur diesel fuel, even at downhill driving conditions, and that nucleation particles can contribute 60% of total particle number emissions. In general, due to sulfur storage and release within the exhaust aftertreatment systems and transients in driving, emissions of nucleation particles can even be the dominant part of modern diesel vehicle exhaust particulate number emissions.

Serum dolichol levels were studied in 95 active alcoholics and 16 abstinent alcoholics (at the time of blood sampling) and compared to those of 41 social drinkers. Active alcoholics had a significantly higher mean serum dolichol concentration (182.7 +/- 5.1 ng/ml, p less than 0.001 than either abstinent alcoholics (138.7 +/- 5.4 ng/ml) or social drinkers (142.1 +/- 4.1 ng/ml). During weekend (48 hr) heavy drinking (5.5 g of alcohol per kg b.w.) no significant changes were seen in mean serum dolichol concentrations in 10 healthy, nonalcoholic volunteers. Neither did moderate drinking for 10 days (60 g of alcohol daily)--preceded and followed by a period of abstinence--produce any significant changes in serum dolichol levels in 10 nonalcoholic subjects. During detoxification treatment of 12 alcoholics, mean serum dolichol concentration stayed constant for the first 7 days; on entering treatment it was 227.7 +/- 15.0 ng/ml, on the 3rd day 238.5 +/- 15.9 ng/ml, and on the 7th day of treatment 222.6 +/- 18.6 ng/ml. Our results show that as well as increasing urinary dolichol excretion, chronic alcohol abuse also produces increased serum dolichol concentrations. However, contrary to urinary dolichols, serum dolichol levels do not react significantly to heavy drinking lasting for 48 hr in nonalcoholic volunteers. Furthermore in alcoholics increased serum dolichol concentrations do not decrease as rapidly during abstinence as urinary dolichol concentrations do.

Vehicle engines produce submicrometer exhaust particles affecting air quality, especially in urban environments. In on-road exhaust studies with a heavy duty diesel vehicle and in laboratory studies with two gasoline-fueled passenger cars, we found that as much as 20-30% of the number of exhaust particles larger than 3 nm may be formed during engine braking conditions-that is, during decelerations and downhill driving while the engine is not fueled. Particles appeared at size ranges extending even below 7 nm and at high number concentrations. Their small size and nonvolatility, coupled with the observation that these particles contain lube-oil-derived metals zinc, phosphorus, and calcium, are suggestive of health risks at least similar to those of exhaust particles observed before. The particles' characteristics indicate that their emissions can be reduced using exhaust after-treatment devices, although these devices have not been mandated for all relevant vehicle types. Altogether, our findings enhance the understanding of the formation vehicle emissions and allow for improved protection of human health in proximity to traffic.

State-of-art light duty diesel vehicles and heavy duty diesel engines are utilized in studying the effect of a novel particle oxidation catalyst (POC ®) on particle emission. In addition to the regulated particulate matter (PM) emission measurement, a real time mass emission and particle number size distribution measurements are utilized in testing. The results show that the particle oxidation catalyst can have a significant decreasing effect on the diesel exhaust particle emissions. For example, in light duty applications PM reductions of 55-61% were achieved over the New European Driving Cycle (NEDC) when using a POC of same size as the engine volume. The usage of a DOC in combination with the POC ensures proper regeneration of the POC substrate. The size distribution measurements revealed that the particle number collection efficiency for smaller particles i.e. the nanoparticles was very high, being close to 100 %.