NUMERICAL SIMULATION OF AERODYNAMIC AND ELECTROSTATIC EFFECTS IN A POWDER COATING FLUIDIZED SYSTEM

The work described in this thesis was carried out for a better understanding of the phenomena in an electrostatic fluidized bed for powder coating. The publications in different areas of science (Computer Science, Chemical Engineering and Electrical Engineering) have been of great help to obtain a final written computer code that combines novel computational methods which aim at simulating the physical effects that occur in any electrostatic fluidized system. One of the main purposes of existing industrial fluidized beds is the coating of metallic pieces. The process to achieve this includes using insulating powder of a particle size appropriate for fluidization. The metallic piece to be coated has to be pre-heated substantially above the melting point of the powder coating material in order to obtain enough enthalpy to cure the required mass of coating insulation. Once this appropriate temperature is reached, the piece is dipped in the fluidized bed for the length of time necessary to acquire a uniform coating. This way of coating in industrial fluidized beds is very inefficient since energy is spent pre-heating the metallic piece and because usually once the dipped piece has been coated, it is placed in an oven again for a new heating period, to finally obtain a uniform surface coating. All these procedures involve substantial increases in energy costs. A new method to obtain uniform powder coated pieces with minimal energy costs was thought of. This idea implies the electrification of the insulating powder particles. In this case if a cold metallic electrically connected to ground piece is dipped in a fluidized bed, the electric field generated by the space charge in the bed will propel the charged particles towards the piece to be coated and remain attached to it. Once taken out of the fluidized bed, the charged particles remain attached (due to the Coulomb attraction force) while the piece is taken to the oven for curing. In 2004, experiments were carried out at the Applied Electrostatic Research Centre (A.E.R.C.) at the University of Western Ontario. An experimental fluidized bed with powder particles was used which included a suction pump system. Through this suction system fluidized powder particles were sucked from the system, and forced to travel around a Teflon tube. Due to the difference of work functions the particles acquired a high positive charge. Furthermore, the particles were injected back into the system, increasing the total net charge of the system. Thus, so when a metallic electrically earthed piece was dipped, due to the Coulomb attraction forces between the charged powder particles in the system and the electrically earthed piece a good surface coating would be obtained. Results from these experiments showed that during injection the total net charge of the system increased for a certain period of time and then gradually decreased. It was concluded that the electrification (injection of highly positive charged particles) of the bed powder had to be carried out only during the time that the piece to be coated was dipped in the bed; otherwise a good coating was not possible. These unexplained findings are the basis for this thesis. In this project, a numerical complex simulation of a fluidized system was performed, for a system with three different size particles (60 pm, 80 pm and 100 pm). Throughout this thesis snapshots of these particles’ positions are shown to better visualize their trajectory paths. After a certain period of time the system acquired a total net charge due to the tribocharging process, at this point a new set of highly positively charged particles (120 pm) was injected. It was expected that the total net charge of the system increases accordingly to the total charge of these new injected particles, however, the total net charge increased up to a certain level and then it seemed to fade away as first stated by the results of the A.E.R.C.’s experiments. The simulations performed in this work tried to reproduce the conditions set in the experiments done in the A.E.R.C. (2004). One of the main achievements was the visualization of the trajectories of all the particles in the system. Appendix 1 presents snapshots of this visualization. Additionally, Chapter 6 shows other insightful results. As mentioned earlier, one of the main objectives of this thesis was to find out why the most efficient coating occurred only when the metallic piece and the positive charged particles were dipped and injected simultaneously. Analyzing the video and graphs obtained the conclusion was that if the injection of charged particles had been done prior to the dipping of the metallic piece, part of the total net charge would have gradually discharged into the electrically earthed walls. Therefore, by the time the earthed metallic piece was dipped the total net charge of the system was not going to be as high as expected which consequently would have ended up in a poor coating

Doctors' labour supply and incentives:a collection of essays

This thesis examines UK doctors’ labour supply from the intensive margin. Initially, it explores trends in average weekly hours of work using data from the Labour Force Survey (LFS). Next, it compares how average weekly hours of work vary over the lifecycle for doctors and compare to with other professionals’ hours (lawyers and accountants). Finally, as doctors continuously report being stressed and unhappy, this thesis explores data from the Annual Population Survey (APS) to assess whether hours of work could alter self-reported wellbeing levels for doctors and other workers. This thesis is made up of five chapters with three main essays on the topic of interest. Chapter 1 conveys an extensive background on what we know about doctors’ labour supply in the UK and other countries. Chapter 2 exploits the LFS to examine main trends in doctors’ weekly hours of work (GPs and hospital doctors) over 21 years (1994-2014). It proposes a definition of total hours worked that encompasses total usual hours in main job (basic hours and overtime hours, paid or unpaid) plus total hours in second job. The chapter is mostly descriptive and focuses on changes in average weekly hours of work of the headcount of doctors over the period and on variation across different characteristics. It also portrays irregular working patterns, second job hours and desired hours of work (both more and fewer hours). The main finding conveys that despite training more doctors every year and the increasing female participation in the medical profession, hours of work have fallen over time and the sharpest fall occurs between 1994 and 2004. From 2004, this trend attenuates but continues falling though at a reduced rate. Chapter 3 estimates labour supply models over the lifecycle for a representative agent using a pooled cross-section dataset from the LFS for ‘partner’ GPs (Selfemployed), ‘salaried’ GPs, hospital doctors, lawyers and accountants. The main finding posits that the reduction in female doctors’ average weekly hours of work – especially ‘salaried’ GPs – has been larger than those of lawyers and accountants. This is attributed to lifecycle effects and, particularly, children. Chapter 4 examines self-reported well-being outcomes (anxiety, happiness, life satisfaction and worthwhile levels) and variables relating health problems (depression, hypertension or whether having a health problem limits activity to work). We examine the relationship between hours of work and well-being levels. Although there is considerable literature on doctors’ job satisfaction, especially GPs, and, also, there are numerous studies on the issue of burnout, this is not the case for well-being of physicians which is underexplored. The few existing studies come from small snapshots and unrepresentative samples. This chapter explores a large well-established dataset using conventional screens to examine the distribution of well-being and their proximate determinants. The information is available in the Annual Population Survey (APS) from 2011 quarter 2 to 2015 quarter 1, covering four fiscal years (2011/12 to 2014/15). Our main finding conveys that, contrary to popular belief, and the assertions of the professional bodies for physicians, doctors appear to be more satisfied, happier, feel that their life is more worthwhile, and they are less anxious than other professionals. The chapter also makes an economic contribution on labour supply: hours of work, at the margin, have virtually no significant effect on the measures of well-being. This means that individuals are on their labour supply curve but those reporting to work more hours may have lower values of the well-being measures. This is true for lawyers and accountants but not for doctors, which is viewed as evidence of intrinsic motivation driven by mission orientation among doctors. So, there is scope for expanding supply along the intensive margin, which may be both an inexpensive and quick solution to the alleged supply shortfall, relative to the current policy of expanding supply along the extensive margin. Chapter 5 sums up the main findings and contributions

Safety and effectiveness of propranolol in severely burned patients: systematic review and meta-analysis

Background The objective of this systematic review was to determine the effectiveness and safety of propranolol compared to placebo or usual care for improving clinical relevant outcomes in severely burned patients (TBSA \u3e20%). Methods Relevant articles from randomized controlled trials were identified by a literature search in MEDLINE, EMBASE, and CENTRAL. We included trials involving patients with a severe burn (\u3e20% of total body surface area affected). Trials were eligible if they evaluated propranolol and compared to usual care or placebo. Two investigators independently assessed articles for inclusion and exclusion criteria and selected studies for the final analysis. We conducted a meta-analysis using a random-effects model. Results We included ten studies in our systematic review. These studies randomized a total of 1236 participants. There were no significant differences between propranolol and placebo with respect to mortality (RD −0.02 [95% CI −0.06 to 0.02]), sepsis (RD −0.03 [95% CI −0.09 to 0.04]), and the overall hospital stay (MD −0.37 [−4.52 to 3.78]). Propranolol-treated adults had a decrease in requirements of blood transfusions (MD −185.64 [95% CI −331.06 to −40.43]) and a decreased heart rate (MD −26.85 [95% CI −39.95 to −13.75]). Conclusions Our analysis indicates that there were no differences in mortality or sepsis in severely burned patients treated with propranolol compared with those who had usual care or placebo. However, the use of propranolol in these patients resulted in lower requirements of blood transfusion and lower values of heart rate. The evidence synthesized in this systematic review is limited to conclude that propranolol reduces the length of hospital stay among severely burned patients. Future trials should assess the impact of propranolol on clinically relevant outcomes such as mortality and adverse events

Spectral variability studies in Active Galactic Nuclei: Exploring continuum and emission line regions in the age of LSST and JWST

The investigation of emission line regions within active galaxies (AGNs) has a rich and extensive history, now extending to the use of AGNs and quasars as "standardizable" cosmological indicators, shedding light on the evolution of our universe. As we enter the era of advanced observatories, such as the successful launch of JWST and the forthcoming Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST), the landscape of AGN exploration across cosmic epochs is poised for exciting advancements. In this work, we delve into recent developments in AGN variability research, anticipating the substantial influx of data facilitated by LSST. The article highlights recent strides made by the AGN Polish Consortium in their contributions to LSST. The piece emphasizes the role of quasars in cosmology, dissecting the intricacies of their calibration as standard candles. The primary focus centers on the relationship between the broad-line region size and luminosity, showcasing recent breakthroughs that enhance our comprehension of this correlation. These breakthroughs encompass a range of perspectives, including spectroscopic analyses, photoionization modeling, and collaborative investigations with other cosmological tools. The study further touches on select studies, underlining how the synergy of theoretical insights and advancements in observational capabilities has yielded deeper insights into these captivating cosmic entities.Comment: 34 pages, 5 figures, accepted for publication as a review in MDPI/Univers

A meta-analysis of resuscitative endovascular balloon occlusion of the aorta (REBOA) or open aortic cross-clamping by resuscitative thoracotomy in non-compressible torso hemorrhage patients

Background The objective of this systematic review and meta-analysis was to determine the effect of REBOA, compared to resuscitative thoracotomy, on mortality and among non-compressible torso hemorrhage trauma patients. Methods Relevant articles were identified by a literature search in MEDLINE and EMBASE. We included studies involving trauma patients suffering non-compressible torso hemorrhage. Studies were eligible if they evaluated REBOA and compared it to resuscitative thoracotomy. Two investigators independently assessed articles for inclusion and exclusion criteria and selected studies for final analysis. We conducted meta-analysis using random effect models. Results We included three studies in our systematic review. These studies included a total of 1276 patients. An initial analysis found that although lower in REBOA-treated patients, the odds of mortality did not differ between the compared groups (OR 0.42; 95% CI 0.17–1.03). Sensitivity analysis showed that the risk of mortality was significantly lower among patients who underwent REBOA, compared to those who underwent resuscitative thoracotomy (RT) (RR 0.81; 95% CI 0.68–0.97). Conclusion Our meta-analysis, mainly from observational data, suggests a positive effect of REBOA on mortality among non-compressible torso hemorrhage patients. However, these results deserve further investigation

SnTox3 Acts in Effector Triggered Susceptibility to Induce Disease on Wheat Carrying the Snn3 Gene

The necrotrophic fungus Stagonospora nodorum produces multiple proteinaceous host-selective toxins (HSTs) which act in effector triggered susceptibility. Here, we report the molecular cloning and functional characterization of the SnTox3-encoding gene, designated SnTox3, as well as the initial characterization of the SnTox3 protein. SnTox3 is a 693 bp intron-free gene with little obvious homology to other known genes. The predicted immature SnTox3 protein is 25.8 kDa in size. A 20 amino acid signal sequence as well as a possible pro sequence are predicted. Six cysteine residues are predicted to form disulfide bonds and are shown to be important for SnTox3 activity. Using heterologous expression in Pichia pastoris and transformation into an avirulent S. nodorum isolate, we show that SnTox3 encodes the SnTox3 protein and that SnTox3 interacts with the wheat susceptibility gene Snn3. In addition, the avirulent S. nodorum isolate transformed with SnTox3 was virulent on host lines expressing the Snn3 gene. SnTox3-disrupted mutants were deficient in the production of SnTox3 and avirulent on the Snn3 differential wheat line BG220. An analysis of genetic diversity revealed that SnTox3 is present in 60.1% of a worldwide collection of 923 isolates and occurs as eleven nucleotide haplotypes resulting in four amino acid haplotypes. The cloning of SnTox3 provides a fundamental tool for the investigation of the S. nodorum-wheat interaction, as well as vital information for the general characterization of necrotroph-plant interactions.This work was supported by USDA-ARS CRIS projects 5442-22000-043-00D and 5442-22000-030-00D

Immunoglobulin T from sea bass (Dicentrarchus labrax L.): Molecular characterization, tissue localization and expression after nodavirus infection

Background Immunoglobulins (Igs) are fundamental components of the adaptive immune system of vertebrates, with the IgT/IgZ isotype specific of Teleosts. In this paper we describe the identification of an IgT heavy chain from the European sea bass (Dicentrarchus labrax L.), its molecular characterization and tissue mRNA localization by in situ hybridization. Results Sea bass IgT consists of 552 aa (Accession Number KM410929) and it contains a putative 19 amino acids long signal peptide and one potential N-glycosylation site. The C-region consists of four CH domains; each contains the cysteine and tryptophan residues required for their correct folding. Based on the recent sequencing of sea bass genome, we have identified five different genomic contigs bearing exons unequivocally pertaining to IgT (CH2, CH3 and CH4), but none corresponded to a complete IgH locus as IgT sequences were found in the highly fragmented assembled genomic regions which could not be assigned to any major scaffold. The 3D structure of sea bass IgT has been modelled using the crystal structure of a mouse Ig gamma as a template, thus showing that the amino acid sequence is suitable for the expected topology referred to an immunoglobulin-like architecture. The basal expression of sea bass IgT and IgM in different organs has been analysed: gut and gills, important mucosal organs, showed high IgT transcripts levels and this was the first indication of the possible involvement of sea bass IgT in mucosal immune responses. Moreover, sea bass IgT expression increased in gills and spleen after infection with nodavirus, highlighting the importance of IgT in sea bass immune responses. In situ hybridization confirmed the presence of IgT transcripts in the gut and it revealed a differential expression along the intestinal tract, with a major expression in the posterior intestine, suggesting the hindgut as a site for the recruitment of IgT+ cells in this species. IgT transcripts were also found in gill filaments and parallel lamellae and, for the first time, we identified scattered IgT positive cells in the liver, with a strong signal in the hepatic parenchyma. Conclusions In conclusion, we performed a full molecular characterization of IgT in sea bass that points out its possible involvement in mucosal immune responses of this species