Characterization of laboratory and real driving emissions of individual Euro 6 light-duty vehicles - Fresh particles and secondary aerosol formation

Emissions from passenger cars are one of major sources that deteriorate urban air quality. This study presents characterization of real-drive emissions from three Euro 6 emission level passenger cars (two gasoline and one diesel) in terms of fresh particles and secondary aerosol formation. The gasoline vehicles were also characterized by chassis dynamometer studies. In the real-drive study, the particle number emissions during regular driving were 1.1-12.7 times greater than observed in the laboratory tests (4.8 times greater on average), which may be caused by more effective nucleation process when diluted by real polluted and humid ambient air. However, the emission factors measured in laboratory were still much higher than the regulatory value of 6 × 10¹¹ particles km^-1. The higher emission factors measured here result probably from the fact that the regulatory limit considers only non-volatile particles larger than 23 nm, whereas here, all particles (also volatile) larger than 3 nm were measured. Secondary aerosol formation potential was the highest after a vehicle cold start when most of the secondary mass was organics. After the cold start, the relative contributions of ammonium, sulfate and nitrate increased. Using a novel approach to study secondary aerosol formation under real-drive conditions with the chase method resulted mostly in emission factors below detection limit, which was not in disagreement with the laboratory findings.

A study on the CO2 and NOx emissions performance of Euro 6 diesel vehicles under various chassis dynamometer and on-road conditions including latest regulatory provisions

The current study presents a detailed analysis of the gaseous emissions, focusing on CO₂ and NO_x, of diesel vehicles under several operating conditions. An assessment is also made on the impact and effectiveness of the Real Driving Emissions (RDE) test, which is mandatory by the European Union (EU) type approval regulation for passenger cars since September 2017. The method followed comprises emissions measurement tests on three Euro 6 diesel vehicles, under laboratory and various on-road operation conditions. Chassis dynamometer tests in the laboratory showed that emissions over the current type approval test (World-wide harmonized Light-duty Test Procedure or WLTP), and over the former one (New European Driving Cycle or NEDC), poorly reflect real-world levels. However, the most demanding CADC testing comes closer to real drive emissions. Comparison of driving conditions on the chassis dynamometer over different driving cycles and on the road reveals that the emission performance substantially varies between different tests, even for apparently similar operation conditions. The NO_x emissions reduction strategy of pre-RDE monitoring Euro 6 vehicles seems to be optimized for the NEDC driving conditions, which are not representative of the real-world driving conditions. The real-world emissions during normal driving conditions are effectively captured with the new RDE test, however driving the vehicle dynamically, at conditions outside the RDE regulation boundaries, results to disproportional high emissions. This is a significant shortcoming which might be critical for populations living on hilly areas or those close to specific micro-environments, such as highway entrance ramps, traffic lights, etc.

Experimental assessment of the potential to decrease diesel NOx emissions beyond minimum requirements for Euro 6 Real Drive Emissions (RDE) compliance

The objective of this study was to test the potential for NO_x emissions improvements on a typical Euro 6 diesel vehicle, following modifications to its emissions control system, under Real Drive Emissions (RDE) testing conditions. A commercially available car was selected and was first measured in its original configuration according to RDE on the road and an initial conformity factor (CF) of 5.4 was determined. Subsequent engine calibration and installation of a Selective Catalytic Reduction (SCR) device were conducted and tested on a fully transient engine dyno setup, which precisely reproduced the engine operation under the on-road RDE test. The NO_x reduction achieved with those upgrades was 90%, leading to a CF of 0.53, with no CO₂ or fuel consumption penalty. These findings demonstrate that diesel vehicles can reach low NO_x levels under real world driving conditions, when well-designed modern exhaust aftertreatment components are installed and properly calibrated.

Multiple Irrigation and Debridements for Periprosthetic Joint Infections: Facing a Necessity or Just Prolonging the Inevitable?

Irrigation and debridement (I&D) may be a viable option in selected cases of periprosthetic joint infections (PJI). Our aim was to investigate the role of multiple I&Ds. Among 141 patients with PJI treated with I&D in our institution, 19 were subjected to additional procedures. Their clinical characteristics were retrospectively reviewed and compared to the remaining patients treated with a single I&D. The probability of treatment failure (removal of implants) was not significantly different among the two groups. The interval between serial I&Ds was a significant factor determining outcomes. Patients treated with multiple I&Ds had a significantly higher prevalence of peripheral vascular disease. The decision to proceed with repeat of I&D should be made with caution.

Total scapulectomy and constrained reverse total shoulder reconstruction for a Ewing's sarcoma

BACKGROUND

Total scapulectomy and intra-articular resection of the glenohumeral joint indicates the Malawer Type III shoulder girdle resection.

MATERIALS AND METHODS

The modified Tikhoff-Linberg total scapulectomy and constrained reverse total shoulder reconstruction for a Ewing's sarcoma of the scapula is presented. A combined approach has been used. The deltoid, trapezius, rhomboids, levator scapulae, latissimus dorsi, and serratus anterior were preserved. the tumor was removed en bloc by disarticulation of the acromioclavicular and the glenohumeral joints. The scapular prosthesis was suspended by the muscles. A constrained reverse humeral prosthesis was implanted after osteotomy of the humeral head.

RESULTS

There were no intraoperative or postoperative complications; surgical margins were clear. At 12 months postoperatively, the patient has a stable and painless shoulder.

CONCLUSION

The goal of shoulder reconstructions is to provide a stable and painless joint that allows positioning of the arm and hand in space. Compared to those patients left without a scapula reconstruction, prosthetic replacement of the scapula and shoulder partially restores abduction and external rotation and improves cosmesis.

Advantages of the Ilizarov external fixation in the management of intra-articular fractures of the distal tibia

Background

Treatment of distal tibial intra-articular fractures is challenging due to the difficulties in achieving anatomical reduction of the articular surface and the instability which may occur due to ligamentous and soft tissue injury. The purpose of this study is to present an algorithm in the application of external fixation in the management of intra-articular fractures of the distal tibia either from axial compression or from torsional forces.

Materials and methods

Thirty two patients with intra-articular fractures of the distal tibia have been studied. Based on the mechanism of injury they were divided into two groups. Group I includes 17 fractures due to axial compression and group II 15 fractures due to torsional force. An Ilizarov external fixation was used in 15 patients (11 of group I and 4 of group II). In 17 cases (6 of group I and 11 of group II) a unilateral hinged external fixator was used. In 7 out of 17 fractures of group I an additional fixation of the fibula was performed.

Results

All fractures were healed. The mean time of removal of the external fixator was 11 weeks for group I and 10 weeks for group II. In group I, 5 patients had radiological osteoarthritic lesions (grade III and IV) but only 2 were symptomatic. Delayed union occurred in 3 patients of group I with fixed fibula. Other complications included one patient of group II with subluxation of the ankle joint after removal of the hinged external fixator, in 2 patients reduction found to be insufficient during the postoperative follow up and were revised and 6 patients had a residual pain. The range of ankle joint motion was larger in group II.

Conclusion

Intra-articular fractures of the distal tibia due to axial compression are usually complicated with cartilaginous problems and are requiring anatomical reduction of the articular surface. Fractures due to torsional forces are complicated with ankle instability and reduction should be augmented with ligament repair, in order to restore normal movement of talus against the mortise. Both Ilizarov and hinged external fixators are unable to restore ligamentous stability. External fixation is recommended only for fractures of the ankle joint caused by axial compression because it is biomechanically superior and has a lower complication rate.

Relatively lower body mass index is associated with an excess of severe truncal asymmetry in healthy adolescents: Do white adipose tissue, leptin, hypothalamus and sympathetic nervous system influence truncal growth asymmetry?

BACKGROUND

In healthy adolescents normal back shape asymmetry, here termed truncal asymmetry (TA), is evaluated by higher and lower subsets of BMI. The study was initiated after research on girls with adolescent idiopathic scoliosis (AIS) showed that higher and lower BMI subsets discriminated patterns of skeletal maturation and asymmetry unexplained by existing theories of pathogenesis leading to a new interpretation which has therapeutic implications (double neuro-osseous theory).

METHODS

5953 adolescents age 11-17 years (boys 2939, girls 3014) were examined in a school screening program in two standard positions, standing forward bending (FB) and sitting FB. The sitting FB position is thought to reveal intrinsic TA free from back humps induced by any leg-length inequality. TA was measured in both positions using a Pruijs scoliometer as angle of trunk inclinations (ATIs) across the back at each of three spinal regions, thoracic, thoracolumbar and lumbar. Abnormality of ATIs was defined as being outside 2 standard deviations for each age group, gender, position and spinal region, and termed severe TA.

RESULTS

In the sitting FB position after correcting for age,relatively lower BMIs are statistically associated with a greater number of severe TAs than with relatively higher BMIs in both girls (thoracolumbar region) and boys (thoracolumbar and lumbar regions).The relative frequency of severe TAs is significantly higher in girls than boys for each of the right thoracic (56.76%) and thoracolumbar (58.82%) regions (p = 0.006, 0.006, respectively). After correcting for age, smaller BMIs are associated with more severe TAs in boys and girls.

DISCUSSION

BMI is a surrogate measure for body fat and circulating leptin levels. The finding that girls with relatively lower BMI have significantly later menarche, and a significant excess of TAs, suggests a relation to energy homeostasis through the hypothalamus. The hypothesis we suggest for the pathogenesis of severe TA in girls and boys has the same mechanism as that proposed recently for AIS girls, namely: severe TAs are initiated by a genetically-determined selectively increased hypothalamic sensitivity (up-regulation, i.e. increased sensitivity) to leptin with asymmetry as an adverse response to stress (hormesis), mediated bilaterally mainly to the growing trunk via the sympathetic nervous system (leptin-hypothalamic-sympathetic nervous system (LHS) concept). The putative autonomic dysfunction is thought to be increased by any lower circulating leptin levels associated with relatively lower BMIs. Sympathetic nervous system activation with asymmetry leads to asymmetries in ribs and/or vertebrae producing severe TA when beyond the capacity of postural mechanisms of the somatic nervous system to control the shape distortion of the trunk. A test of this hypothesis testing skin sympathetic responses, as in the Rett syndrome, is suggested.

Trunk asymmetry in juveniles

BACKGROUND

Trunk asymmetry (TA) is a common phenomenon in children, but its incidence in juveniles is not known. The present cross sectional study reports TA in normal juveniles and provides data which describe the evolution of TA from early childhood to adolescence.

MATERIALS AND METHODS

The scoliometer readings in both standing and sitting forward bending position (FBP) of 3301 children, (1645 boys, and 1656 girls) aged from 3 to 9 years old were studied. TA was quantified by measuring angle of trunk rotation (ATR) and children were categorized as symmetric (ATR = 0 degrees ), mild asymmetric (ATR 1 degrees - 6 degrees ) and severely asymmetric (ATR >/= 7 degrees ). The difference of TA between standing and sitting FBP as well as differences between boys and girls in frequency of TA were also calculated. The scoliometer readings were analyzed by age to reveal at which age the juvenile pattern of TA changes into the adolescent one.

RESULTS

74.2% of boys and 77% of girls were symmetric (ATR = 0 degrees ) in the thoracic region in standing FBP, while 82.7% of boys and 84.1% of girls were symmetric in the thoracic region in sitting FBP. Juvenile girls are more symmetric than boys but severe TA was found almost the same between the two genders. A significant reduction in the frequency of mild TA from standing into sitting FBP, in all the examined regions in both boys and girls was found, but in severe TA this reduction is very small. Analysing scoliometer readings by age it appears that significant TA changes take place between 8-9 years of age for boys and between 6-7 and 8-9 years for girls. TA in boys is changing into the adolescent pattern at a later age than in girls.

CONCLUSION

Juveniles were found more symmetric than adolescents, who were studied previously in a different study. Furthermore, juvenile girls were found more symmetric than boys. Juvenile TA pattern seems to be in accordance with the higher incidence of juvenile idiopathic scoliosis in boys. Furthermore, severe TA, which could be correlated with a scoliotic curve, was found to be more common to the left side. The present report provides information about the variability of back morphology in normal juveniles. The amount of TA in children is the indicator for referral and further orthopaedic assessment if a spinal curve is detected, but can also be used as a baseline for further research on idiopathic scoliosis aetiology.

Study of trunk asymmetry in normal children and adolescents

The scoliometer readings in both standing and sitting position of 2071 children and adolescents (1099 boys and 972 girls) aged from 5 to 18 years old were studied. The angle of trunk rotation (ATR) was measured, in order to quantify the existing trunk asymmetry. Children and adolescents were divided in two groups according to the severity of trunk asymmetry. In the first group asymmetry was 1 to 6 degrees and in the second group was 7 or more degrees. Radiographic and leg length inequality evaluation were also performed in a number of children. The mean frequency of symmetric (ATR = 0 degrees) boys and girls was 67.06% and 65.01% for the standing screening position and 76.5% and 75.1% for the sitting position, respectively. The mean difference of frequency of asymmetry (ATR > 0 degrees) at standing minus sitting forward bending position for boys and girls was 10.22% and 9.37%, respectively. The mean frequency of asymmetry of 7 or more degrees was 3.23% for boys and 3.92% for girls at the standing forward bending position and 1.62% and 2.21% at the sitting, respectively. Girls are found to express higher frequency of asymmetry than boys. Right trunk asymmetry was more common than left. The sitting position is the preferred screening position for examining the rib or loin hump during school screening as it demonstrates the best correlation with the spinal deformity exposing the real trunk asymmetry.

The influence of brace on quality of life of adolescents with idiopathic scoliosis

Traditionally, the effectiveness of brace treatment on adolescents with IS is based on curve magnitude and to some extent on vertebral rotation and rib hump. QoL has been introduced in the recent years in order to evaluate the effectiveness of brace treatment. The aim of the study is to determine the influence of brace on quality of life (QoL) of adolescents with idiopathic scoliosis (IS).Thirty-six patients with a mean age of 13,9 (range 12-17) years old, a mean Cobb angle 28,2 degrees (range 19-38 degrees and a mean angle of trunk inclination (ATI) 7,8 degrees (range 4 degrees -17 degrees) who were treated conservatively with a modified Boston brace for a minimum of 2 years, filled the form of Brace Questionnaire (BrQ). BrQ is a validated, disease specific instrument, its score ranges from 20 to 100 and higher BrQ scores mean better quality of life. Correlations were determined by the Pearson correlation coefficient, with p<0.05 considered significant. Mean overall score of BrQ was 73,8 (SD 15. 8). Lower scores were observed in physical functioning (55,4, SD 15,9) and vitality (55, SD 25,9). School activity (98, SD 4,4) was affected less. The Cobb angle correlated significantly only with school activity (p<0,02). The ATI correlated significantly with social functioning (thoracolumbar ATI, p<0.038; lumbar ATI, p<0.035). There were no significant correlations between either Cobb angle or ATI with BrQ overall scores. Cobb angle and ATI significantly influenced school activity and social functioning respectively, but not general health perception, physical functioning, emotional functioning, vitality, bodily pain and self-esteem and aesthetics.