Impacts and mitigation of excess diesel-related NOx emissions in 11 major vehicle markets.

Vehicle emissions contribute to fine particulate matter (PM2.5) and tropospheric ozone air pollution, affecting human health, crop yields and climate worldwide. On-road diesel vehicles produce approximately 20 per cent of global anthropogenic emissions of nitrogen oxides (NOx), which are key PM2.5 and ozone precursors. Regulated NOx emission limits in leading markets have been progressively tightened, but current diesel vehicles emit far more NOx under real-world operating conditions than during laboratory certification testing. Here we show that across 11 markets, representing approximately 80 per cent of global diesel vehicle sales, nearly one-third of on-road heavy-duty diesel vehicle emissions and over half of on-road light-duty diesel vehicle emissions are in excess of certification limits. These excess emissions (totalling 4.6 million tons) are associated with about 38,000 PM2.5- and ozone-related premature deaths globally in 2015, including about 10 per cent of all ozone-related premature deaths in the 28 European Union member states. Heavy-duty vehicles are the dominant contributor to excess diesel NOx emissions and associated health impacts in almost all regions. Adopting and enforcing next-generation standards (more stringent than Euro 6/VI) could nearly eliminate real-world diesel-related NOx emissions in these markets, avoiding approximately 174,000 global PM2.5- and ozone-related premature deaths in 2040. Most of these benefits can be achieved by implementing Euro VI standards where they have not yet been adopted for heavy-duty vehicles.

On-road emissions of passenger cars beyond the boundary conditions of the real-driving emissions test.

Passenger cars are an important source of air pollution, especially in urban areas. Recently, real-driving emissions (RDE) test procedures have been introduced in the EU aiming to evaluate nitrogen oxides (NOx) and particulate number (PN) emissions from passenger cars during on-road operation. Although RDE accounts for a large variety of real-world driving, it excludes certain driving situations by setting boundary conditions (e.g., in relation to altitude, temperature or dynamic driving). The present work investigates the on-road emissions of NOx, NO2, CO, particle number (PN) and CO2 from a fleet of 19 Euro 6b, 6c and 6d-TEMP vehicles, including diesel, gasoline (GDI and PFI) and compressed natural gas (CNG) vehicles. The vehicles were tested under different on-road driving conditions outside boundaries. These included 'baseline' tests, but also testing conditions beyond the RDE boundary conditions to investigate the performance of the emissions control devices in demanding situations. Consistently low average emission rates of PN and CO were measured from all diesel vehicles tested under most conditions. Moreover, the tested Euro 6d-TEMP and Euro 6c diesel vehicles met the NOx emission limits applicable to Euro 6d-TEMP diesel vehicles during RDE tests (168 mg/km). The Euro 6b GDI vehicle equipped with a gasoline particulate filter (GPF) presented PN emissions < 6 × 1011 #/km. These results, in contrast with previous on-road measurements from earlier Euro 6 vehicles, indicate more efficient emission control technologies are currently being used in diesel and gasoline vehicles. At the same time, the results suggest that particular attention should be given to CO and PN emissions of certain types of vehicles when driven under dynamic conditions, and possibly additional work is necessary. In particular, the emissions of CO (measured in this study during the regulated RDE test, but without an emission limit associated to it) or PN from PFI vehicles (presently not covered by the Euro 6 standard) showed elevated results in some occasions. Emissions of CO were up to 7.5 times higher when the more dynamic tests were conducted and the highest PN emissions were measured from a PFI gasoline vehicle during dynamic driving. Although based on a limited sample of cars, our work points to the relevance of a technology- and fuel-neutral approach to vehicle emission standards, whereby all vehicles must comply with the same emission limits for all pollutants.

Framework for the assessment of PEMS (Portable Emissions Measurement Systems) uncertainty.

European regulation 2016/427 (the first package of the so-called Real-Driving Emissions (RDE) regulation) introduced on-road testing with Portable Emissions Measurement Systems (PEMS) to complement the chassis dynamometer laboratory (Type I) test for the type approval of light-duty vehicles in the European Union since September 2017. The Not-To-Exceed (NTE) limit for a pollutant is the Type I test limit multiplied by a conformity factor that includes a margin for the additional measurement uncertainty of PEMS relative to standard laboratory equipment. The variability of measured results related to RDE trip design, vehicle operating conditions, and data evaluation remain outside of the uncertainty margin. The margins have to be reviewed annually (recital 10 of regulation 2016/646). This paper lays out the framework used for the first review of the NOx margin, which is also applicable to future margin reviews. Based on experimental data received from the stakeholders of the RDE technical working group in 2017, two NOx margin scenarios of 0.24-0.43 were calculated, accounting for different assumptions of possible zero drift behaviour of the PEMS during the tests. The reduced uncertainty margin compared to the one foreseen for 2020 (0.5) reflects the technical improvement of PEMS over the past few years.

Evaluation of Exhaust Emissions from Three Diesel-Hybrid Cars and Simulation of After-Treatment Systems for Ultralow Real-World NOx Emissions.

Hybridization offers great potential for decreasing pollutant and carbon dioxide emissions of diesel cars. However, an assessment of the real-world emissions performance of modern diesel hybrids is missing. Here, we test three diesel-hybrid cars on the road and benchmark our findings with two cars against tests on the chassis dynamometer and model simulations. The pollutant emissions of the two cars tested on the chassis dynamometer were in compliance with the relevant Euro standards over the New European Driving Cycle and Worldwide harmonized Light vehicles Test Procedure. On the road, all three diesel-hybrids exceeded the regulatory NOx limits (average exceedance for all trips: +150% for the Volvo, +510% for the Peugeot, and +550% for the Mercedes-Benz) and also showed elevated on-road CO2 emissions (average exceedance of certification values: +178, +77, and +52%, respectively). These findings point to a wide discrepancy between certified and on-road CO2 and suggest that hybridization alone is insufficient to achieve low-NOx emissions of diesel powertrains. Instead, our simulation suggests that properly calibrated selective catalytic reduction filter and lean-NOx trap after-treatment technologies can reduce the on-road NOx emissions to 0.023 and 0.068 g/km on average, respectively, well below the Euro 6 limit (0.080 g/km).

Experimental Assessment of NOx Emissions from 73 Euro 6 Diesel Passenger Cars.

Controlling nitrogen oxides (NOx) emissions from diesel passenger cars during real-world driving is one of the major technical challenges facing diesel auto manufacturers. Three main technologies are available for this purpose: exhaust gas recirculation (EGR), lean-burn NOx traps (LNT), and selective catalytic reduction (SCR). Seventy-three Euro 6 diesel passenger cars (8 EGR only, 40 LNT, and 25 SCR) were tested on a chassis dynamometer over both the European type-approval cycle (NEDC, cold engine start) and the more realistic Worldwide harmonized light-duty test cycle (WLTC version 2.0, hot start) between 2012 and 2015. Most vehicles met the legislative limit of 0.08 g/km of NOx over NEDC (average emission factors by technology: EGR-only 0.07 g/km, LNT 0.04 g/km, and SCR 0.05 g/km), but the average emission factors rose dramatically over WLTC (EGR-only 0.17 g/km, LNT 0.21 g/km, and SCR 0.13 g/km). Five LNT-equipped vehicles exhibited very poor performance over the WLTC, emitting 7-15 times the regulated limit. These results illustrate how diesel NOx emissions are not properly controlled under the current, NEDC-based homologation framework. The upcoming real-driving emissions (RDE) regulation, which mandates an additional on-road emissions test for EU type approvals, could be a step in the right direction to address this problem.

Self-Efficacy in Nursing Competencies during Students' Clinical Practicum: The Development of a Self-Assessment Scale.

The evaluation of the competencies corresponding to the different professional profiles of future nursing graduates is fundamental to their training. In this regard, students' self-evaluation must be part of their training. This study aimed to develop and psychometrically test the Perceived Self-Efficacy in Nursing Competencies (PSENC) Scale. This study was conducted in two phases: selecting and adjusting items and assessing the instrument's psychometric properties. A sample of 1416 students completed the scale online. Exploratory factor and confirmatory factor analyses were conducted. Inferential analysis was carried out. The exploratory factor analysis of the PSENC scale with 20 items resulted in five factors (76.3% of variance). All factors showed Cronbach's alpha coefficients > 0.70. The confirmatory factor analysis measurement model showed satisfactory and adequate goodness-of-fit indices. The developed scale showed the psychometric adequacy and usefulness to the self-assessment of nursing students regarding their self-efficacy expectations in competencies during their clinical practicum. This study was not registered.

Successful pharmaco-invasive approach using a lower alteplase dose and VA-ECMO support in high-risk pulmonary embolism: case report.

Despite the elevated mortality rates associated with high-risk pulmonary embolism (PE), this condition remains understudied. Data regarding the effectiveness and safety of invasive therapies such as venoarterial extracorporeal membrane oxygenation (VA-ECMO) in this patient population remains controversial. Here, we present the case of a 61-year-old male with high-risk PE associated with refractory cardiac arrest and cardiogenic shock who underwent a combination of extracorporeal cardiopulmonary resuscitation with VA-ECMO and pharmaco-invasive therapy (mechanical thrombi fragmentation plus lower alteplase dose), resulting in successful pulmonary reperfusion. After a prolonged in-hospital stay, the patient was discharged in stable condition.

Vocational Value Profiles of Students with Preferential Vocational Interest in Sport and Their Relationship with Personal and Academic Wellbeing.

In recent years there has been a significant increase in the number of students who choose to pursue university studies related to the field of sports. However, there are no studies that have investigated the existence of differentiated profiles within students whose preferred vocational area is sport. The main objective of this study was to establish the profiles of students in the second year of Spain Bachillerato whose preferred vocational interest is sport, according to the two representative vocational values: (a) "to have a fun professional activity"; and (b) "to have a professional activity whose schedule makes it possible to reconcile personal and professional life". In addition, the resulting groups were compared according to their perception of general and academic wellbeing and their identification with the other vocational values. Two hundred and thirty participants (MAge = 17.47; DTAge = 0.669; N = 171; 74.3% male and N = 59; 25.7% female) completed some validated measures. Three clusters emerged which did not differ in terms of general and academic wellbeing. Differences were found though in terms of some vocational values such "to help people", "to develop one's entrepreneurial initiative" or "to be self-employed". The findings invite us to rethink the differences in the specific profiles of vocational values and their impact on employability opportunities, and to consider these approaches in the orientation of students who have among their priority options to study sport sciences.

Applying the social cognitive model of well-being in the nursing clinical practicum: A structural equation modeling analysis with a Spanish student's sample.

BACKGROUND: Clinical education, understanding as practicum, plays a key role in nursing education but has been identified as the most challenging and stressful experience for nursing students. Promoting student satisfaction and well-being during clinical practice has a significant effect on learning outcomes, retention and attrition. OBJECTIVES: To examine the predictive power of a social cognitive model of wellbeing when applied to explain academic satisfaction in the clinical practicum and overall life satisfaction of Spanish nursing students. DESIGN/PARTICIPANTS: A cross-sectional correlational study was conducted at four Spanish nursing schools in a 586 student's sample. METHODS: Data were collected through a self-reported questionnaire that included measures of academic support, self-efficacy, goal progress, academic satisfaction, life satisfaction and trait positive affect. The research model was evaluated through structural equation modeling. RESULTS: The proposed model fit well in the full sample and accounted for substantial portions of the variance in academic (50%) and life satisfaction (21%). Most of the hypotheses formulated were verified. The model was invariant across academic year. CONCLUSIONS: The results indicated global support for the social cognitive model of academic satisfaction as a guide for developing interventions to facilitate the positive adjustment and wellbeing of nursing students in the practicum.

Nursing students' perception of academic support in the practicum: Development of a reliable and valid measurement instrument.

BACKGROUND: The importance of practicum training in health sciences disciplines places prominence on the academic support received by students in this learning environment, both due to its leverage over their perceived level of satisfaction of academic proficiency as well as its impact on their academic performance. AIM: The aim of this study was to develop and validate a scale which facilitates the evaluation of academic support perceived by nursing students during their practicum. PARTICIPANTS: The sample is made up of 710 students from three academic levels of the Bachelor's Degree in Nursing. METHOD: An instrument to evaluate the level of academic support perceived by the students was developed and validated. Subsequently, a measurement model of the dimensions which comprise the academic support in the practicum was created. RESULTS: The Academic Support in the Practicum Scale demonstrated high internal consistency, with a Cronbach's alpha value=0.913. The validation of the measurement instrument was carried out using confirmatory factor analysis and multi-sample analysis techniques, which presented positive goodness-of-fit indices. CONCLUSIONS: The developed tool has shown sufficient validity and high internal consistency. Its adequate psychometric properties lead to the conclusion that the scale provides a reliable and valid measurement of academic support perceived by students during their placement.

Development and review of Euro 5 passenger car emission factors based on experimental results over various driving cycles.

The emissions of CO2 and regulated pollutants (NOx, HC, CO, PM) of thirteen Euro 5 compliant passenger cars (seven gasoline, six Diesel) were measured on a chassis dynamometer. The vehicles were driven repeatedly over the European type-approval driving cycle (NEDC) and the more dynamic WMTC and CADC driving cycles. Distance-specific emission factors were derived for each pollutant and sub-cycle, and these were subsequently compared to the corresponding emission factors provided by the reference European models used for vehicle emission inventory compilation (COPERT and HBEFA) and put in context with the applicable European emission limits. The measured emissions stayed below the legal emission limits when the type-approval cycle (NEDC) was used. Over the more dynamic cycles (considered more representative of real-world driving) the emissions were consistently higher but in most cases remained below the type-approval limit. The high NOx emissions of Diesel vehicles under real-world driving conditions remain the main cause for environmental concern regarding the emission profile of Euro 5 passenger cars. Measured emissions of NOx exceeded the type-approval limits (up to 5 times in extreme cases) and presented significantly increased average values (0.35 g/km for urban driving and 0.56 g/km for motorway driving). The comparison with the reference models showed good correlation in all cases, a positive finding considering the importance of these tools in emission monitoring and policy-making processes.