Comparison of turbulent reactive spray characteristics of different renewable fuels using Large Eddy Simulation

The human-caused climate change imposes many challenges for future generations. It is commonly agreed to stop the global warming process, and new technologies have to be found to reduce the footprint of greenhouse gases. A high share of greenhouse gas emissions comes from the transport sector. In particular, carbon dioxide CO2 from the combustion of fossil fuels in engines contributes significantly to global warming. The reduction of emissions in the transport sector can either be achieved by decarbonization, eliminating energy carriers containing carbon, or defossilation, including combustion of carbon-neutral fuels. The defossilation pathway is currently favored, and many fuels from renewable sources are in the focus of research. Two very promising carbon-neutral Diesel fuels are 1-Octanol, which is produced from biogenic feedstock, and the group of Polyoxymethylene ethers (OME) that are synthesized from green hydrogen and ambient carbon dioxide. Both fuels are considered backstop technologies, which makes them very interesting in sustainable energy production. Both fuels exhibit changed thermophysical and chemical kinetic properties compared to conventional fossil fuels. The latent heat of evaporation of 1-Octanol is significantly increased compared to Diesel. Also, OME shows higher latent heat of evaporation and a significantly increased vapor pressure. The reactivity of 1-Octanol is reduced, while OME is considered a high-reactive fuel due to its high level of oxygenation. Both fuels show no soot formation and can be utilized in blends with regular fuels to meet new emission regulations. Furthermore, emissions of CO, CO2, NOx and soot can be significantly reduced with 1-Octanol and OME. In the present thesis, the spray flame ignition is examined for the renewable fuels 1-Octanol and OME and compared with the Diesel surrogate n-Dodecane. The investigation utilizes a high-fidelity Large Eddy Simulation framework coupled with a tabulated flamelet-generated manifold combustion model. In particular, the influence of the changed thermophysical properties on mixture formation is elucidated. Further, the effect of the changed thermophysical properties on ignition is investigated. Also, the influence of the changed chemical kinetic properties on ignition is examined. The impact of the latent heat of evaporation on ignition will be elucidated. The flame structures of 1-Octanol and OMEmix are compared to the Diesel reference fuel n-Dodecane. The analysis is performed in an automotive, heavy-duty and marine injector with increasing nozzle sizes, and the influence of the nozzle size on ignition is discussed. Excellent agreement of the Large Eddy Simulations under inert conditions with experimental data regarding liquid penetration and vapor penetration length is achieved. The mixture formation analysis of the automotive Engine Combustion Network (ECN) Spray A3 injector shows that 1-Octanol and n-Dodecane exhibit a similar mixture formation process, while OMEmix shows higher values of the scalar dissipation rate and a narrower spray shape. The mixture formation process in the heavy-duty ECN Spray D and marine injector from Woodward L'Orange show delayed mixture formation. The large particle diameter leads to reduced drag and consecutive less momentum exchange and heat transfer to the liquid phase. The temperature distribution of the gas phase clearly shows that the heat loss due to evaporation of 1-Octanol is pronounced. The comparison of the adiabatic mixing line assumed in the combustion model and the temperature distribution in the spray revealed that the higher heat capacity of n-Dodecane inherently leads to a more concave shape of the adiabatic mixing line. This fuel property makes n-Dodecane less sensitive to spray cooling effects on ignition. The flame structure is first investigated utilizing laminar non-premixed 1D flamelet simulations. OMEmix shows the highest reactivity and the lowest ignition delay times for different scalar dissipation rates at stoichiometry. Furthermore, the highest ignition limit is observed for OMEmix. Compared to OMEmix, the ignition delay time of n-Dodecane is increased, and its ignition limit is significantly lower. 1-Octanol shows the highest ignition delay times at lower scalar dissipation rates at stoichiometry. In the proximity of the ignition limit of n-Dodecane, the ignition delay time of 1-Octanol is shorter, which is explained by an increased reactivity of 1-Octanol during the high-temperature ignition. A novel flamelet model is derived that incorporates the heat losses due to evaporation based on the results from the analysis of the gas temperature distribution of the spray. In contrast to methods from the literature, the presented model is physically consistent and does not change the spray flame structure. The novel flamelet model is utilized in the reactive spray simulations for all fuels and injectors investigated. The typical onset of ignition over the spray head in ECN Spray A3 has been confirmed for all fuels. In contrast, the start of ignition at the spray flanks has been observed in the ECN Spray D and the marine injector from Woodward L'Orange. In this thesis, a cause-effect mechanism has been identified that explains the different ignition locations. The onset of ignition in mixture fraction space is similar for each fuel in all injectors. This finding suggests that the mixture formation process dominates the ignition location. The comparison of different-sized nozzles shows that the lowest ignition delay time is found for Spray A3, and the ignition delay time of the larger nozzles is increased. The trend from the flamelet simulation of the lowest ignition delay time for OMEmix is also observed in the spray flame. OMEmix exhibits a significantly different mixture formation and ignition behavior than 1-Octanol and n-Dodecane, due to its high stoichiometric mixture fraction. The mixture formation process of n-Dodecane and 1-Octanol is similar, while the ignition delay time of n-Dodecane is shorter than that of 1-Octanol. The influence of heat loss due to evaporation is very prominent for 1-Octanol. The flamelet model without the heat-loss correction underestimates the ignition delay time by 25%. The heat-loss corrected model perfectly aligns with the experimental ignition delay time. Overall, this thesis contributes to the understanding of the ignition of spray flames with renewable Diesel fuels. Significant differences in the mixture formation process have been identified and explained with the changed thermophysical properties. A novel flamelet model incorporating heat loss due to latent heat of evaporation is developed and successfully utilized in the simulation of reactive sprays in LES. Perfect agreement by means of ignition delay time and flame structure has been achieved. This thesis significantly contributes to a deeper understanding of renewable fuels in the context of defossilation. The results of this thesis can be utilized to develop new technologies that reduce greenhouse gases in the transport sector and slow down global warming

Ablation of rat TRPV1-expressing Adelta/C-fibers with resiniferatoxin: analysis of withdrawal behaviors, recovery of function and molecular correlates

<p>Abstract</p> <p>Background</p> <p>Ablation of TRPV1-expressing nociceptive fibers with the potent capsaicin analog resiniferatoxin (RTX) results in long lasting pain relief. RTX is particularly adaptable to focal application, and the induced chemical axonopathy leads to analgesia with a duration that is influenced by dose, route of administration, and the rate of fiber regeneration. TRPV1 is expressed in a subpopulation of unmyelinated C- and lightly myelinated Adelta fibers that detect changes in skin temperature at low and high rates of noxious heating, respectively. Here we investigate fiber-type specific behaviors, their time course of recovery and molecular correlates of axon damage and nociception using infrared laser stimuli following an RTX-induced peripheral axonopathy.</p> <p>Results</p> <p>RTX was injected into rat hind paws (mid-plantar) to produce thermal hypoalgesia. An infrared diode laser was used to stimulate Adelta fibers in the paw with a small-diameter (1.6 mm), high-energy, 100 msec pulse, or C-fibers with a wide-diameter (5 mm), long-duration, low-energy pulse. We monitored behavioral responses to indicate loss and regeneration of fibers. At the site of injection, responses to C-fiber stimuli were significantly attenuated for two weeks after 5 or 50 ng RTX. Responses to Adelta stimuli were significantly attenuated for two weeks at the highest intensity stimulus, and for 5 weeks to a less intense Adelta stimulus. Stimulation on the toe, a site distal to the injection, showed significant attenuation of Adelta responses for 7- 8 weeks after 5 ng, or 9-10 weeks after 50 ng RTX. In contrast, responses to C-fiber stimuli exhibited basically normal responses at 5 weeks after RTX. During the period of fiber loss and recovery, molecular markers for nerve regeneration (ATF3 and galanin) are upregulated in the dorsal root ganglia (DRG) when behavior is maximally attenuated, but markers of nociceptive activity (c-Fos in spinal cord and MCP-1 in DRG), although induced immediately after RTX treatment, returned to normal.</p> <p>Conclusion</p> <p>Behavioral recovery following peripheral RTX treatment is linked to regeneration of TRPV1-expressing Adelta and C-fibers and sustained expression of molecular markers. Infrared laser stimulation is a potentially valuable tool for evaluating the behavioral role of Adelta fibers in pain and pain control.</p

Wellbeing at Work — Emotional Impact on Workers Using a Worker Guidance System Designed for Positive User Experience

Wellbeing at work can be achieved through different strategies; designing for a positive user experience (UX) is one way. However, the relationship between wellbeing and professionally used technology is rather unexplored, especially in work areas that are far from desktop work such as worker guidance systems (WGSs) used in assembly processes. In this paper, we first described a qualitative evaluation (using the valence method) of a prototype WGS designed for a positive UX. The evaluation showed that it elicited far more positive than negative feelings. Based on the results, we improved and redesigned the prototype. We then implemented it in a realistic setting and quantitatively compared it with an established WGS. It was shown that the prototype elicited more positive feelings than the established system, whereas there were no differences in the number of negative markers. Thus, one can assume that the improvement of UX in the redesigned system was due to the positive UX design concepts. However, there were no significant differences in the mood questionnaires. The paper showed that positive experiences at work can be achieved when the design of professional technology is focused on a positive UX. Long-term studies should further investigate whether these experiences lead to a generally elevated mood

Experience with targeted next generation sequencing for the care of lung cancer: Insights into promises and limitations of genomic oncology in day-to-day practice

Introduction Tumor genotyping using single gene assays (SGAs) is standard practice in advanced non-small-cell lung cancer (NSCLC). We evaluated how the introduction of next generation sequencing (NGS) into day-to-day clinical practice altered therapeutic decision-making. Methods Clinicopathologic data, tumor genotype, and clinical decisions were retrospectively compiled over 6 months following introduction of NGS assay use at our institution in 82 patient-tumor samples (7 by primary NGS, 22 by sequential SGAs followed by NGS, and 53 by SGAs). Results SGAs identified abnormalities in 34 samples, and all patients with advanced EGFR-mutated or ALK-rearranged tumors received approved tyrosine kinase inhibitors (TKIs) or were consented for clinical trials. NGS was more commonly requested for EGFR, ALK, and KRAS-negative tumors (p<0.0001). NGS was successful in 24/29 (82.7%) tumors. Of 17 adenocarcinomas (ACs), 11 (7 from patients with ≤15 pack-years of smoking) had abnormalities in a known driver oncogene. This led to a change in decision-making in 8 patients, trial consideration in 6, and off-label TKI use in 2. Of 7 squamous cell (SC) carcinomas, 1 had a driver aberration (FGFR1); 6 had other genomic events (all with TP53 mutations). In no cases were clinical decisions altered (p=0.0538 when compared to ACs). Conclusions Targeted NGS can identify a significant number of therapeutically-relevant driver events in lung ACs; particularly in never or light smokers. For SC lung cancers, NGS is less likely to alter current practice. Further research into the cost effectiveness and optimal use of NGS and improved provider training in genomic oncology are warranted

Guidelines for Genome-Scale Analysis of Biological Rhythms

Genome biology approaches have made enormous contributions to our understanding of biological rhythms, particularly in identifying outputs of the clock, including RNAs, proteins, and metabolites, whose abundance oscillates throughout the day. These methods hold significant promise for future discovery, particularly when combined with computational modeling. However, genome-scale experiments are costly and laborious, yielding “big data” that are conceptually and statistically difficult to analyze. There is no obvious consensus regarding design or analysis. Here we discuss the relevant technical considerations to generate reproducible, statistically sound, and broadly useful genome-scale data. Rather than suggest a set of rigid rules, we aim to codify principles by which investigators, reviewers, and readers of the primary literature can evaluate the suitability of different experimental designs for measuring different aspects of biological rhythms. We introduce CircaInSilico, a web-based application for generating synthetic genome biology data to benchmark statistical methods for studying biological rhythms. Finally, we discuss several unmet analytical needs, including applications to clinical medicine, and suggest productive avenues to address them

Human Cytomegalovirus IE1 Protein Elicits a Type II Interferon-Like Host Cell Response That Depends on Activated STAT1 but Not Interferon-γ

Human cytomegalovirus (hCMV) is a highly prevalent pathogen that, upon primary infection, establishes life-long persistence in all infected individuals. Acute hCMV infections cause a variety of diseases in humans with developmental or acquired immune deficits. In addition, persistent hCMV infection may contribute to various chronic disease conditions even in immunologically normal people. The pathogenesis of hCMV disease has been frequently linked to inflammatory host immune responses triggered by virus-infected cells. Moreover, hCMV infection activates numerous host genes many of which encode pro-inflammatory proteins. However, little is known about the relative contributions of individual viral gene products to these changes in cellular transcription. We systematically analyzed the effects of the hCMV 72-kDa immediate-early 1 (IE1) protein, a major transcriptional activator and antagonist of type I interferon (IFN) signaling, on the human transcriptome. Following expression under conditions closely mimicking the situation during productive infection, IE1 elicits a global type II IFN-like host cell response. This response is dominated by the selective up-regulation of immune stimulatory genes normally controlled by IFN-γ and includes the synthesis and secretion of pro-inflammatory chemokines. IE1-mediated induction of IFN-stimulated genes strictly depends on tyrosine-phosphorylated signal transducer and activator of transcription 1 (STAT1) and correlates with the nuclear accumulation and sequence-specific binding of STAT1 to IFN-γ-responsive promoters. However, neither synthesis nor secretion of IFN-γ or other IFNs seems to be required for the IE1-dependent effects on cellular gene expression. Our results demonstrate that a single hCMV protein can trigger a pro-inflammatory host transcriptional response via an unexpected STAT1-dependent but IFN-independent mechanism and identify IE1 as a candidate determinant of hCMV pathogenicity

Guidelines for Genome-Scale Analysis of Biological Rhythms

Genome biology approaches have made enormous contributions to our understanding of biological rhythms, particularly in identifying outputs of the clock, including RNAs, proteins, and metabolites, whose abundance oscillates throughout the day. These methods hold significant promise for future discovery, particularly when combined with computational modeling. However, genome-scale experiments are costly and laborious, yielding ‘big data’ that is conceptually and statistically difficult to analyze. There is no obvious consensus regarding design or analysis. Here we discuss the relevant technical considerations to generate reproducible, statistically sound, and broadly useful genome scale data. Rather than suggest a set of rigid rules, we aim to codify principles by which investigators, reviewers, and readers of the primary literature can evaluate the suitability of different experimental designs for measuring different aspects of biological rhythms. We introduce CircaInSilico, a web-based application for generating synthetic genome biology data to benchmark statistical methods for studying biological rhythms. Finally, we discuss several unmet analytical needs, including applications to clinical medicine, and suggest productive avenues to address them