Influence of Post-Injection Parameters on Soot Formation and Oxidation in a Common-Rail-Diesel Engine Using Multi-Color-Pyrometry

2012 ◽  
Author(s):  
Christophe Barro ◽  
Frédéric Tschanz ◽  
Peter Obrecht ◽  
Konstantinos Boulouchos
Keyword(s):  
Oxidation Rate ◽  
Time Window ◽  
Soot Formation ◽  
General Rule ◽  
Soot Oxidation ◽  
Lower Amount ◽  
Post Injection ◽  
Heat Addition ◽  
Underlying Mechanisms ◽  
A Minor

The emission trade-off between soot and NOx is an issue of major concern in automotive diesel applications. Measures need to be taken both on the engine and on the aftertreatment sides in order to optimize the engine emissions while maintaining the highest possible efficiency. It is known that post injections have a potential for exhaust soot reduction without any significant influence in the NOx emissions. However, an accurate and general rule of how to parameterize a post injection such that it provides a maximum reduction of soot emissions does not exist. Moreover, the underlying mechanisms are not understood in detail. The experimental investigation presented here provides insight into the fundamental mechanisms of soot formation and reduction due to post injections under different turbulence and reaction kinetic conditions. In parallel to the measurement of soot elementary carbon in the exhaust (using a Photo Acoustic Soot Sensor), the in-cylinder soot formation and oxidation process have been investigated with an Optical Light Probe (OLP). This sensor provides crank angle resolved information about the in-cylinder soot evolution. The experiments confirm conclusions of earlier works that soot reduction due to a post injection is mainly based on two reasons: increased turbulence (from the post injection) during soot oxidation and lower soot formation due to lower amount of fuel in the main combustion at similar load conditions. A third effect of heat addition during the soot oxidation, which was often mentioned in the literature, could not be confirmed. In addition, the experiments show that variations of turbulence (from swirl) and reaction kinetics have a minor influence on the diffusion controlled heat release rate. However, the time phasing of the soot evolution is highly influenced by these variations with only small changes in the peak soot concentration. It is shown that the soot reduction of a post injection depends on the timing. More precisely, the soot reduction capability of a post injection decreases rapidly as soon as its timing is late in the soot oxidation phase. The soot oxidation rate can only be improved by increased turbulence and heat addition from the post injection in a time window before the in-cylinder soot peak occurs. Depending on EGR and swirl level, a maximum dwell time can be defined after which the post injection effect becomes counterproductive with respect to the soot oxidation rate.

Application of a Phenomenological Soot Model for Diesel Engine Combustion

2008 ◽  
Author(s):  
Xiaobei Cheng ◽  
Hongling Jv ◽  
Yifeng Wu
Keyword(s):  
Diesel Engine ◽  
Chemical Reactions ◽  
Oxidation Rate ◽  
Soot Formation ◽  
Soot Oxidation ◽  
Soot Concentration ◽  
Engine Operation ◽  
Soot Particles ◽  
Turbulent Eddies ◽  
Soot Model

The application of the improved CFD code for the simulation of combustion and emission formation in a high-speed diesel engine has been presented and discussed. The soot concentration transport equation is found and solved together with all other flow equations. A slip correction factor is introduced into this equation. In turbulent combustion, the soot particles are contained within the turbulent eddies, and burnt up swiftly with the dissipation of these eddies in the soot oxidation zone. However, the chemical reactions always process except the dissipation of turbulent eddies and the intermixing of soot particles and turbulent eddies. The soot oxidation rate should be controlled simultaneity by the chemical reactions rate and the dissipation rate of turbulent eddies. A hybrid particle turbulent transport controlled rate and soot oxidation rate model is present in this paper and Soot formation and oxidation processes have been modeled according to this model. A reasonable agreement of the measured and computed data of in-cylinder pressure, soot, and NO emissions for different engine operation conditions has been made. The precision of simulated soot concentration is improved compare with the commonly Hiroyasu—Nagel—Strickland (HNS) soot model.

Study on the Mechanism of Soot Reduction by Multi-Injection Coupled with EGR

2013 ◽  
Vol 805-806 ◽  
pp. 1759-1762 ◽  
Author(s):  
Jing Luo ◽  
Hai Feng Liu
Keyword(s):  
Oxidation Rate ◽  
Positive Impact ◽  
Soot Oxidation ◽  
Injection Timing ◽  
Pilot Injection ◽  
Soot Emission ◽  
Post Injection ◽  
Multiple Injections ◽  
Injection Quantity ◽  
Heavy Duty Diesel

The effects of multiple injections coupled with medium EGR (25% - 30%) on heavy duty diesel engine were investigated. Injection timing and mass were adjusted with different injection strategies (main-post and pilot-main) to study the influence of these parameters on combustion and emissions. The mechanism of soot emission reduction was discussed. Results indicate that, at fixed total injection quantity and EGR rate, NOx is reduced, while soot is decreased followed by an increasing with increasing post injection quantity; NOx nearly kept constant and soot declined before rising with lager main-post interval. Optimum post injection could accelerate soot oxidation rate. Pilot injection has no positive impact on NOx, while soot decreases with less pilot fuel mass and lager pilot-main interval. Optimum pilot injection could be beneficial for a better mixture property. The acceleration of soot oxidation rate is the basic reason of soot emission reducing by multiple injections.

scholarly journals Pharmacological rescue of cognitive function in a mouse model of chemobrain

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Lien D. Nguyen ◽  
Tom T. Fischer ◽  
Barbara E. Ehrlich
Keyword(s):  
Cognitive Impairment ◽  
Prefrontal Cortex ◽  
Calcium Oscillations ◽  
Neuronal Morphology ◽  
Post Injection ◽  
Object Recognition Test ◽  
Cognitive Changes ◽  
Memory Acquisition ◽  
Underlying Mechanisms ◽  
Trisphosphate Receptor

Abstract Background After chemotherapy, many cancer survivors suffer from long-lasting cognitive impairment, colloquially known as “chemobrain.” However, the trajectories of cognitive changes and the underlying mechanisms remain unclear. We previously established paclitaxel-induced inositol trisphosphate receptor (InsP3R)-dependent calcium oscillations as a mechanism for peripheral neuropathy, which was prevented by lithium pretreatment. Here, we investigated if a similar mechanism also underlay paclitaxel-induced chemobrain. Method Mice were injected with 4 doses of 20 mg/kg paclitaxel every other day to induced cognitive impairment. Memory acquisition was assessed with the displaced object recognition test. The morphology of neurons in the prefrontal cortex and the hippocampus was analyzed using Golgi-Cox staining, followed by Sholl analyses. Changes in protein expression were measured by Western blot. Results Mice receiving paclitaxel showed impaired short-term spatial memory acquisition both acutely 5 days post injection and chronically 23 days post injection. Dendritic length and complexity were reduced in the hippocampus and the prefrontal cortex after paclitaxel injection. Concurrently, the expression of protein kinase C α (PKCα), an effector in the InsP3R pathway, was increased. Treatment with lithium before or shortly after paclitaxel injection rescued the behavioral, cellular, and molecular deficits observed. Similarly, memory and morphological deficits could be rescued by pretreatment with chelerythrine, a PKC inhibitor. Conclusion We establish the InsP3R calcium pathway and impaired neuronal morphology as mechanisms for paclitaxel-induced cognitive impairment. Our findings suggest lithium and PKC inhibitors as candidate agents for preventing chemotherapy-induced cognitive impairment.

scholarly journals Possibilities of Simultaneous In-Cylinder Reduction of Soot andNOxEmissions for Diesel Engines with Direct Injection

2008 ◽  
Vol 2008 ◽  
pp. 1-13 ◽  
Author(s):  
U. Wagner ◽  
P. Eckert ◽  
U. Spicher
Keyword(s):  
Nitrogen Oxide ◽  
Diesel Engines ◽  
Fuel Injection ◽  
Soot Formation ◽  
Soot Oxidation ◽  
The Other ◽  
Injection System ◽  
Nitrogen Oxide Emissions ◽  
Injection Strategy ◽  
Soot Emissions

Up to now, diesel engines with direct fuel injection are the propulsion systems with the highest efficiency for mobile applications. Future targets in reducingCO2-emissions with regard to global warming effects can be met with the help of these engines. A major disadvantage of diesel engines is the high soot and nitrogen oxide emissions which cannot be reduced completely with only engine measures today. The present paper describes two different possibilities for the simultaneous in-cylinder reduction of soot and nitrogen oxide emissions. One possibility is the optimization of the injection process with a new injection strategy the other one is the use of water diesel emulsions with the conventional injection system. The new injection strategy for this experimental part of the study overcomes the problem of increased soot emissions with pilot injection by separating the injections spatially and therefore on the one hand reduces the soot formation during the early stages of the combustion and on the other hand increases the soot oxidation later during the combustion. Another method to reduce the emissions is the introduction of water into the combustion chamber. Emulsions of water and fuel offer the potential to simultaneously reduceNOxand soot emissions while maintaining a high-thermal efficiency. This article presents a theoretical investigation of the use of fuel-water emulsions in DI-Diesel engines. The numerical simulations are carried out with the 3D-CFD code KIVA3V. The use of different water diesel emulsions is investigated and assessed with the numerical model.

RyR1 exhibits lower gain of CICR activity than RyR3 in the SR: evidence for selective stabilization of RyR1 channel

2004 ◽  
Vol 287 (1) ◽  
pp. C36-C45 ◽  
Author(s):  
Takashi Murayama ◽  
Yasuo Ogawa
Keyword(s):  
Binding Sites ◽  
Skeletal Muscles ◽  
Specific Activity ◽  
Adenine Nucleotides ◽  
Minor Effect ◽  
Mammalian Skeletal Muscle ◽  
Selective Stabilization ◽  
Underlying Mechanisms ◽  
A Minor

We showed that frog α-ryanodine receptor (α-RyR) had a lower gain of Ca2+-induced Ca2+ release (CICR) activity than β-RyR in sarcoplasmic reticulum (SR) vesicles, indicating selective “stabilization” of the former isoform (Murayama T and Ogawa Y. J Biol Chem 276: 2953–2960, 2001). To know whether this is also the case with mammalian RyR1, we determined [3H]ryanodine binding of RyR1 and RyR3 in bovine diaphragm SR vesicles. The value of [3H]ryanodine binding (B) was normalized by the number of maximal binding sites (Bmax), whereby the specific activity of each isoform was expressed. This B/Bmax expression demonstrated that ryanodine binding of individual channels for RyR1 was <15% that for RyR3. Responses to Ca2+, Mg2+, adenine nucleotides, and caffeine were not substantially different between in situ and purified isoforms. These results suggest that the gain of CICR activity of RyR1 is markedly lower than that of RyR3 in mammalian skeletal muscle, indicating selective stabilization of RyR1 as is true of frog α-RyR. The stabilization was partly eliminated by FK506 and partly by solubilization of the vesicles with CHAPS, each of which was additive to the other. In contrast, high salt, which greatly enhances [3H]ryanodine binding, caused only a minor effect on the stabilization of RyR1. None of the T-tubule components, coexisting RyR3, or calmodulin was the cause. The CHAPS-sensitive intra- and intermolecular interactions that are common between mammalian and frog skeletal muscles and the isoform-specific inhibition by FKBP12, which is characteristic of mammals, are likely to be the underlying mechanisms.

scholarly journals Are COVID-19 mitigation measures reducing preterm birth rate in China?

2021 ◽  
Vol 6 (8) ◽  
pp. e006359
Author(s):  
Zheng Bian ◽  
Xiaoxian Qu ◽  
Hao Ying ◽  
Xiaohua Liu
Keyword(s):  
Preterm Birth ◽  
Birth Rate ◽  
Time Window ◽  
Time Windows ◽  
Mitigation Measures ◽  
Late Preterm Birth ◽  
Child Morbidity ◽  
Preterm Birth Rate ◽  
Underlying Mechanisms ◽  
The Impact

ObjectivePreterm birth is the leading cause of child morbidity and mortality globally. We aimed to determine the impact of the COVID-19 mitigation measures implemented in China on 23 January 2020 on the incidence of preterm birth in our institution.DesignLogistic regression analysis was used to investigate the association between the national COVID-19 mitigation measures implemented in China and the incidence of preterm birth.SettingShanghai First Maternity and Infant Hospital, Shanghai China.ParticipantsAll singleton deliveries abstracted from electronic medical record between 1 January 2014 to 31 December 2020.Main outcome measuresPreterm birth rate.ResultsData on 164 107 singleton deliveries were available. COVID-19 mitigation measures were consistently associated with significant reductions in preterm birth in the 2-month, 3-month, 4-month, 5-month time windows after implementation (+2 months, OR 0.80, 95% CI 0.69 to 0.94; +3 months, OR 0.83, 95% CI 0.73 to 0.94; +4 months, OR 0.82, 95% CI 0.73 to 0.92; +5 months, OR 0.84, 95% CI 0.76 to 0.93). These reductions in preterm birth were obvious across various degrees of prematurity, but were statistically significant only in moderate-to-late preterm birth (32 complete weeks to 36 weeks and 6 days) subgroup. The preterm birth difference disappeared gradually after various restrictions were removed (7th–12th month of 2020, OR 1.02, 95% CI 0.94 to 1.11). There was no difference in stillbirth rate across the study time window.ConclusionSubstantial decreases in preterm birth rates were observed following implementation of the national COVID-19 mitigation measures in China. Further study is warranted to explore the underlying mechanisms associated with this observation.

scholarly journals Underlying physiological and biomechanical mechanisms related to postural control of Parkour practitioners: a pilot study

2021 ◽  
Vol 15 (2) ◽  
pp. 65-78
Author(s):  
André F. V. Veneroso ◽  
Patrick W. Segundo ◽  
Daniela Godoi
Keyword(s):  
Postural Control ◽  
Sensory Information ◽  
Lower Amount ◽  
Soft Or ◽  
Art Of Living ◽  
State Of Mind ◽  
Underlying Mechanisms ◽  
Base Of Support ◽  
The Given ◽  
Control Balance

BACKGROUND: Parkour can be seen as a sport, an art, a philosophy, a state of mind, an art of living. Practitioners (known as “tracers”) have to overcome obstacles in their path by adapting their movements to the given environment to reach somewhere or something or to escape from someone or something. However, the knowledge about the underlying mechanisms related to postural control in tracers is still lacking. AIM: To examine the postural control in tracers using global, structural, and spectral stabilometric descriptors. METHOD: Five tracers and five controls, all-male, stood upright for 30 seconds, under different conditions of vision (open or closed eyes), surface (soft or rigid), and base of support (bipedal, semi-tandem, or Parkour stance). RESULTS: In more challenging conditions, the tracers compared to controls, showed a lower amount of sway, needed less postural commands, and used sensory information to control balance differently. CONCLUSION: Tracers have better postural control than controls. Moreover, although current findings are based on data from a small number of subjects, the results suggest that these differences between groups are related to different underlying physiological and biomechanical mechanisms related to postural control.

scholarly journals Penicillium simplicissimum NL-Z1 Induced an Imposed Effect to Promote the Leguminous Plant Growth

2021 ◽  
Vol 12 ◽  
Author(s):  
Jiayao Zhuang ◽  
Chao Liu ◽  
Xiaoxue Wang ◽  
Tongxin Xu ◽  
Hao Yang
Keyword(s):  
Plant Growth ◽  
Rock Slope ◽  
Plant Biomass ◽  
Control Treatment ◽  
Leguminous Plant ◽  
Penicillium Simplicissimum ◽  
Nodule Biomass ◽  
Underlying Mechanisms ◽  
Phosphate Solubilizing ◽  
A Minor

It is found effective for phytoremediation of the guest soil spraying method by adding microbes to promote the growth of arbor leguminous plant on a high and steep rock slope. However, its underlying mechanisms remain elusive. Here, some experiments were conducted to explore the multifunctions of Penicillium simplicissimum NL-Z1 on rock weathering, nodule growth, and beneficial microbial regulation. The results show that P. simplicissimum NL-Z1 significantly increased the release of phosphorus, potassium, calcium, and magnesium from the rock by 226, 29, 24, and 95%, respectively, compared with that of the control. A significant increase of 153% in Indigofera pseudotinctoria Matsum nodule biomass, accompanied by an increase of 37% in the leguminous plant biomass was observed in the P. simplicissimum NL-Z1 treatment than in the control treatment. Interestingly, even though P. simplicissimum NL-Z1 itself became a minor microbial community in the soil, it induced a significant increase in Mortierella, which, as a beneficial microbe, can promote phosphate-solubilizing and plant growth. The results suggest that P. simplicissimum NL-Z1 could induce an imposed effect to promote leguminous plant growth, which may be conducive to the development of the phytoremediation technique for high and steep rock slope. The study provides a novel thought of using the indirect effect of microbes, i.e., promoting other beneficial microbes, to improve soil environment.

scholarly journals SARS-CoV-2 and the Brain: What Do We Know about the Causality of ‘Cognitive COVID?

2021 ◽  
Vol 10 (15) ◽  
pp. 3441
Author(s):  
Hashir Ali Awan ◽  
Mufaddal Najmuddin Diwan ◽  
Alifiya Aamir ◽  
Muneeza Ali ◽  
Massimo Di Giannantonio ◽  
...  
Keyword(s):  
Olfactory Pathway ◽  
Cognitive Sequelae ◽  
Significant Burden ◽  
Inflammatory State ◽  
Underlying Mechanisms ◽  
Acute Changes ◽  
A Minor

The second year of the COVID-19 (coronavirus disease) pandemic has seen the need to identify and assess the long-term consequences of a SARS-CoV-2 infection on an individual’s overall wellbeing, including adequate cognitive functioning. ‘Cognitive COVID’ is an informal term coined to interchangeably refer to acute changes in cognition during COVID-19 and/or cognitive sequelae with various deficits following the infection. These may manifest as altered levels of consciousness, encephalopathy-like symptoms, delirium, and loss of various memory domains. Dysexecutive syndrome is a peculiar manifestation of ‘Cognitive COVID’ as well. In the previous major outbreaks of viruses like SARS-CoV, MERS-CoV and Influenza. There have been attempts to understand the underlying mechanisms describing the causality of similar symptoms following SARS-CoV-2 infection. This review, therefore, is attempting to highlight the current understanding of the various direct and indirect mechanisms, focusing on the role of neurotropism of SARS-CoV-2, the general pro-inflammatory state, and the pandemic-associated psychosocial stressors in the causality of ‘Cognitive COVID.’ Neurotropism is associated with various mechanisms including retrograde neuronal transmission via olfactory pathway, a general hematogenous spread, and the virus using immune cells as vectors. The high amounts of inflammation caused by COVID-19, compounded with potential intubation, are associated with a deleterious effect on the cognition as well. Finally, the pandemic’s unique psychosocial impact has raised alarm due to its possible effect on cognition. Furthermore, with surfacing reports of post-COVID-vaccination cognitive impairments after vaccines containing mRNA encoding for spike glycoprotein of SARS-CoV-2, we hypothesize their causality and ways to mitigate the risk. The potential impact on the quality of life of an individual and the fact that even a minor proportion of COVID-19 cases developing cognitive impairment could be a significant burden on already overwhelmed healthcare systems across the world make it vital to gather further evidence regarding the prevalence, presentation, correlations, and causality of these events and reevaluate our approach to accommodate early identification, management, and rehabilitation of patients exhibiting cognitive symptoms.

scholarly journals Experimental and computational investigation of temperature effects on soot mechanisms

2014 ◽  
Vol 79 (7) ◽  
pp. 881-895 ◽  
Author(s):  
Xiaojie Bi ◽  
Maoyu Xiao ◽  
Xinqi Qiao ◽  
Chia-Fon Lee ◽  
Liu Yu
Keyword(s):  
Ambient Temperature ◽  
Soot Formation ◽  
Oxidation Mechanism ◽  
Soot Oxidation ◽  
Ambient Temperatures ◽  
Operation Conditions ◽  
Constant Volume Chamber ◽  
Soot Mass ◽  
Soot Measurement ◽  
Soot Model

Effects of initial ambient temperatures on combustion and soot emission characteristics of diesel fuel were investigated through experiment conducted in optical constant volume chamber and simulation using phenomenological soot model. There are four difference initial ambient temperatures adopted in our research: 1000 K, 900 K, 800 K and 700 K. In order to obtain a better prediction of soot behavior, phenomenological soot model was revised to take into account the soot oxidation feedback on soot number density and good agreement was observed in the comparison of soot measurement and prediction. Results indicated that ignition delay prolonged with the decrease of initial ambient temperature. The heat release rate demonstrated the transition from mixing controlled combustion at high ambient temperature to premixed combustion mode at low ambient temperature. At lower ambient temperature, soot formation and oxidation mechanism were both suppressed. But finally soot mass concentration reduced with decreasing initial ambient temperature. Although the drop in ambient temperature did not cool the mean in-cylinder temperature during the combustion, it did shrink the total area of local high equivalence ratio, in which soot usually generated fast. At 700 K initial ambient temperature, soot emissions were almost negligible, which indicates that sootless combustion might be achieved at super low initial temperature operation conditions.

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