In an attempt to improve ambient air quality, retrofit programmes have been encouraged; targeting reductions in PM emissions by means of diesel particulate filters (DPFs). However depending on the DPF design and operating conditions increased nitrogen dioxide (NO;) emissions have been observed, which is causing concern. Previous work showed that retrofitting a DPF system employing a fuel borne catalyst (FBC) to facilitate regeneration, reduced NO 2 emissions. This paper outlines\the investigation of a base metal coated DPF to enhance the reduction of NO 2 . Such a DPF system has been fitted to older technology buses and has demonstrated reliable field performance.
Exhaust emissions legislation for diesel engines generally limits only the mass of emitted particulate matter. This limitation reflects the concerns and measurement technology at the time the legislation was drafted. However, evolving diesel particulate filter (DPF) systems offer the potential for reductions in the mass and more importantly, the number of particles emitted from diesel exhausts. Particulate filters require frequent cleaning or regeneration of accumulated soot, if the engine is to continue to operate satisfactorily. Exothermic reactions during regeneration can lead to severe thermal gradients in the filter system resulting in damage. Fuel additives have been evaluated to show significant reductions in light off temperature which allow frequent small regeneration events to occur, under mild operating conditions. The resulting small exotherms suggest that low back pressure filter systems giving frequent regenerations could in the future become as reliable in use as gasoline exhaust catalyst systems.
Due to concerns over NO2 emissions from platinum catalysts a base metal catalysed diesel particulate filter (DPF) has been developed and used in combination with fuel borne catalysts (FBC). Results are presented showing reductions in HC, NOX, NO2, and PAH emissions along with an assessment of the emissions of metals used in the FBC and the catalysed DPF. This data is used to show the likely reduction in overall iron and other metal emissions as a result of using the catalysed DPF/FBC system. A similar system has also been assessed for durability for over 2000 hours when fitted to a bus in regular service in Switzerland.
Two varieties of conditions of shock may be isolated during necrotic amoebic colitis (13 cases). Eight patients present a simple hypovolemic shock secondary to wastage by diarrhea and perilesional oedema with globular, protein, alcaline and potassic deficiency. Its prognosis is relatively good, after vascular infilling and corrections of metabolic disorders. Five other patients present real toxi-infectious shock resulting from widespread tissue necrosis with auto-intoxication associated with septicemic complications. Its prognosis is frankly bad. The treatment is far more difficult. The use of cardiovascular analeptics, such as dopamine, after an infilling failure, is not always sufficient to re-establish the situation. The exeresis of necrotic tissues is an indispensable condition to remove the cause of the shock before septicaemic generalisation.
Background: The new class of "CFTR modulator" drugs restore function to mutant channels in cystic fibrosis (CF) patients and lead to improvements in body-mass index and lung function especially in younger patients. While it is anticipated that early treatment with CFTR modulators will significantly delay the onset of advanced lung disease, lung neutrophils and inflammatory cytokines remain high in modulator-treated CF patients with established lung disease, underscoring the need to identify and ultimately target the source of this inflammation in CF lung. Methods: Stem cell cloning technology developed to resolve pathogenic stem cell heterogeneity in COPD lung was applied to lungs of cystic fibrosis patients (3 homozygous CFTR-F508D; 1 CFTR-F508D/L1254X; FEV1/FCV 14-30%) undergoing therapeutic lung transplantation. Single cell-derived clones corresponding to the six stem cell variants resolved by single cell RNA sequencing of these libraries were assessed by RNA-sequencing and xenografting to monitor inflammation, fibrosis, and mucin secretion. The impact of CFTR activity on these variants following gene complementation or exposure to CFTR modulators was assessed by molecular and functional studies.Findings: CF lungs display a stem cell heterogeneity marked by six predominant variants of which three are proinflammatory at the level of gene expression and their ability to drive neutrophil inflammation in xenografts in immunodeficient mice. The proinflammatory functions of these three variants were not reversible by genetic or pharmacological restoration of CFTR activity.Interpretation: The emergence of three proinflammatory stem cell variants in CF lung may explain the persistence of lung inflammation in CF patients undergoing CFTR modulator therapy.Funding: National Heart Lung and Blood Institute (NHLBI) of the NIH, Cancer Prevention and Research Institute of Texas (CPRIT), Cancer Research United Kingdom (CRUK).Declaration of Interest: W.X., F.D.M., M.D. and M.V. have filed patents related to technologies used in the present work. W.X, F.D.M., and M.V. have financial interests in MultiClonal Therapeutics, Inc. and Tract Pharmaceuticals, Inc.Ethical Approval: The lung tissues used in this study were from resected lobes, lung transplants, or fetal demise cases that were obtained under informed consent as de-identified material under approved institutional review board protocols at the University of Connecticut Health Sciences (IRB# 08-310-1), the University of Iowa Carver College of Medicine (IRB# 199507432), the University of Texas Health Sciences Center, Houston (HSC-MS-08- 0354/HSC-MS-15-1049), and the Brigham and Women’s Hospital, Boston, MA (2009P002281), respectively.
A novel dosing system for fuel borne catalyst (FBC), used to assist regeneration with a diesel particulate filter (DPF), has been developed. The system was designed for on-board vehicle use to overcome problems encountered with batch dosing systems. Important design features were simplicity, to minimise system cost, and the use of in-line dosing rather than batch dosing linked to tank refuelling. The paper describes the development of the dosing system which continuously doses FBC into the fuel line feeding the engine injection pump. The theoretical considerations behind the concept are explored, together with the realities imposed by fuelling regimes in which a variable proportion of the fuel flowing through the injection pump is passed back to the fuel tank. Two types of system are considered, ie where 1) FBC is added to the fuel in direct proportion to the flow rate of fuel and 2) FBC is added at a constant time-based rate. Modelling of changes in the concentration of FBC in the fuel over time indicated significant non-linearity with both approaches. Bed testing with a diesel engine equipped with a DPF assessed both flow-based and time-based dosing concepts. The test work demonstrated that the in-line FBC dosing concept could achieve reliable regeneration with either system. The averaging effect of soot accumulation over time on the ratio of metal to soot within the DPF apparently accounts for successful regeneration despite big variations in FBC concentration. The paper describes the application of the system to light duty vehicles such as Black Cabs used in central London. Data loggers indicated successful operation on several vehicles over distances ranging from 12,000 to 20,000km. An in-line FBC dosing system was also fitted to a heavy duty fire appliance support vehicle for additional tests. Data to date suggest that this application has produced acceptable DPF regeneration performance. Test work on this vehicle continues.
