Optimisation of autoselective plasma regeneration of wall-flow diesel particulate filters

The increase in number of diesel powered vehicles has led to greater concern for the effects of their exhaust emissions. Engine manufacturers must now consider using diesel particulate filters to make their engines meet the legislated limits. Diesel particulate filters can remove more than 95% of the particulates from the exhaust flow but require cleaning, known as regeneration. This thesis describes the research and optimisation of the Autoselective regeneration system for cordierite wall flow diesel particulate filters. The novel Autoselective technology uses an atmospheric pressure glow discharge plasma to selectively oxidise particulate matter (soot) trapped within the filter. The aim of this research was to produce a regeneration system that can operate under all exhaust conditions with a low energy demand and no precious metal dependence to compete with the numerous pre-existing technologies. The effect of discharge electrode type and position on regeneration performance has been investigated in terms of regeneration uniformity, power requirement and regeneration rate. The results showed that the electrode orientation had a large effect on regeneration distribution and energy demand. The electrode capacitance and breakdown voltage was shown to affect the choice of power supply circuit because not all power supply topologies were suitable for powering electrodes with >100 pF capacitance. A number of power supplies were designed and tested, a voltage driven resonant transformer type supply was shown to be optimal when used in conjunction with a swept frequency. The current and frequency ranges of electrical discharges were continuously variable, and their effect on discharge regeneration performance was studied. The results showed that the discharge frequency had no effect on the regeneration process but did affect spatial distribution. An optimised resonant transformer power supply was designed that was ideally suited for the electrodes used. A novel power modulation strategy, which used a switching frequency phase locked to the ~ iii ~ modulating frequency, was employed which extended the operating range of the discharge to below 10 mA for electrode separations > 7.5 mm. The heat flows within the filter and discharge during regeneration were analysed and the filter damage process was linked to the heat released by the discharge inside the filter wall. Other filter materials were compared based on the findings and Mullite ceramic was identified as a potentially better filter material for Autoselective regeneration. The filtration efficiency is important and was observed to be affected by the Autoselective process. The effect of the discharge on filtration efficiency was studied and the mechanism of particulate re-entrainment was identified as a combination of electrostatic and electro-acoustic forces. The Autoselective technology was successfully implemented in both flow-rig and on-engine tests. Results showed significant reduction in back-pressure for power inputs of ~ 500 W. The understanding of the Autoselective regeneration system has been improved and the research resulted in a novel method of filter regeneration

Codifying healthcare – big data and the issue of misclassification

The rise of electronic medical records has led to a proliferation of large observational studies that examine the perioperative period. In contrast to randomized controlled trials, these studies have the ability to provide quick, cheap and easily obtainable information on a variety of patients and are reflective of everyday clinical practice. However, it is important to note that the data used in these studies are often generated for billing or documentation purposes such as insurance claims or the electronic anesthetic record. The reliance on codes to define diagnoses in these studies may lead to false inferences or conclusions. Researchers should specify the code assignment process and be aware of potential error sources when undertaking studies using secondary data sources. While misclassification may be a short-coming of using large databases, it does not prevent their use in conducting meaningful effectiveness research that has direct consequences on medical decision making

Low power auto selective regeneration of monolithic wall flow diesel particulate filters

This paper presents research into a novel autoselective electric discharge method for regenerating monolithic wall flow diesel particulate filters using low power over the entire range of temperatures and oxygen concentrations experienced within the exhaust systems of modern diesel engines. The ability to regenerate the filter independently of exhaust gas temperature and composition significantly reduces system complexity compared to other systems. In addition, the system does not require catalyst loading and uses only massproduced electronic and electrical components, thus reducing the cost of the after-treatment package. Purpose built exhaust gas simulation test rigs were used to evaluate, develop and optimise the autoselective regeneration system. On-engine testing demonstrated the performance of the autoselective regeneration process under real engine conditions. Typical regeneration performance is presented and discussed with the aid of visual observations, particulate mass measurements, back pressure measurements and energy consumption. The research demonstrates the potential of the novel autoselective method for diesel particulate filter regeneration. The autoselective process does not require an exhaust by-pass and enables the system to be low power, catalyst-free and exhaust temperature independent

Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.

Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability

Understanding the Medical Chemistry of the Cannabis Plant is Critical to Guiding Real World Clinical Evidence

While cannabis has been consumed for thousands of years, the medical-legal landscape surrounding its use has dramatically evolved over the past decades. Patients are turning to cannabis as a therapeutic option for several medical conditions. Given the surge in interest over the past decades there exists a major gap in the literature with respect to understanding the products that are currently being consumed by patients. The current perspective highlights the lack of relevance within the current literature towards understanding the medical chemistry of the products being consumed. The cannabis industry must rigorously invest into understanding what people are consuming from a chemical composition standpoint. This will inform what compounds in addition to &Delta;9-tetrahydrocannabinol and cannabidiol may be producing physiologic/therapeutic effects from plant based extracts. Only through real-world evidence and a formalized, granular data collection process within which we know the chemical inputs for patients already using or beginning to use medical cannabis, we can come closer to the ability to provide targeted clinical decision making and design future appropriate randomized controlled trials

Understanding the Medical Chemistry of the Cannabis Plant is Critical to Guiding Real World Clinical Evidence

While cannabis has been consumed for thousands of years, the medical-legal landscape surrounding its use has dramatically evolved over the past decades. Patients are turning to cannabis as a therapeutic option for several medical conditions. Given the surge in interest over the past decades there exists a major gap in the literature with respect to understanding the products that are currently being consumed by patients. The current perspective highlights the lack of relevance within the current literature towards understanding the medical chemistry of the products being consumed. The cannabis industry must rigorously invest into understanding what people are consuming from a chemical composition standpoint. This will inform what compounds in addition to &Delta;9-tetrahydrocannabinol and cannabidiol may be producing physiologic/therapeutic effects from plant based extracts. Only through real-world evidence and a formalized, granular data collection process within which we know the chemical inputs for patients already using or beginning to use medical cannabis, we can come closer to the ability to provide targeted clinical decision making and design future appropriate randomized controlled trials

Association of Vitamin D Status and Acute Rhinosinusitis: Results From the United States National Health and Nutrition Examination Survey 2001–2006

Abstract Although vitamin D status may be a modifiable risk factor for various respiratory ailments, limited data exists regarding its role in sinonasal infections. Our goal was to investigate the association of 25-hydroxyvitamin D (25OHD) levels with acute rhinosinusitis (ARS) in a large, nationally representative sample of non-institutionalized individuals from the United States. In this cross-sectional study of individuals ≥17 years from the National Health and Nutrition Examination Survey 2001–2006, we used multivariable regression analysis to investigate the association of 25OHD levels with ARS, while adjusting for season, demographics (age, sex, race, and poverty-to-income ratio), and clinical data (smoking, asthma, chronic obstructive pulmonary disease, diabetes mellitus, and neutropenia). A total of 3921 individuals were included in our analyses. Median 25OHD level was 22 (interquartile range 16–28) ng/mL. Overall, 15.8% (95% confidence interval [CI] 14.4–17.7) of participants reported ARS within the 24 hours leading up to their survey participation. After adjusting for season, demographics, and clinical data, 25OHD levels were associated with ARS (odds ratio 0.88, 95% CI 0.78–0.99 per 10 ng/mL). When vitamin D status was dichotomized, 25OHD levels <20 ng/mL were associated with 33% higher odds of ARS (odds ratio 1.33, 95% CI 1.03–1.72) compared with levels ≥20 ng/mL. Our analyses suggest that 25OHD levels are inversely associated with ARS. Randomized, controlled trials are warranted to determine the effect of optimizing vitamin D status on the risk of sinonasal infections

Prospective preference assessment for the Comparison of Analgesic Regimen Effectiveness and Safety in Surgery (CARES) trial

Abstract Background Clinical trials face major barriers such as under-enrollment and selective enrollment, which threaten study completion and undermine validity and generalizability. Thus, we conducted a prospective preference assessment (PPA) prior to commencing the Comparison of Analgesic Regimen Effectiveness and Safety in Surgery (CARES) trial—a randomized controlled study comparing the outcomes of managing acute postoperative pain between opioid-sparing and opioid-based therapies. This PPA aimed to (1) determine the patients’ willingness to participate in the CARES trial, (2) identify the areas for improvement, and (3) assess the differences between willing and unwilling patients. Methods Patients undergoing elective laparoscopic cholecystectomy were recruited between August 2019 and February 2020 from two academic hospitals. A survey was administered to each patient consisting of (1) a vignette describing the trial, (2) an assessment of the patients’ understanding of the trial, (3) open-ended questions assessing the attitudes towards the trial, and (4) patient-completed questionnaires. Data were analyzed qualitatively with thematic analysis and quantitatively with the Wilcoxon signed-rank and chi-square tests. Results Forty-two patients were enrolled and grouped based on the 6-point Likert scale into willing (4–6, 71%) and not willing (1–3, 29%) to participate in the CARES trial. There were no significant differences with respect to all variables: age, education, sex, visible minority status, previous research, previous surgery, regular use of pain medications, surgical concerns, previous discussions on pain management, significant pain within the past 3 months, and significant use of pain medication within the past month. Factors that motivated participation were contributing to scientific research (45%), altruism (29%), and improving personal pain (24%). Common discouraging factors were negative perceptions of opioids (29%), side effects (21%), being blinded to the study medication (21%), and poor pain management (19%). Conclusions This PPA revealed that two key discouraging factors for patients were being blinded to the type of pain medication being taken and the potential for poor pain management as a consequence of participation. Modifications to improve patient acceptance of the CARES trial include ensuring sufficient rescue medicine and follow-up visits consistent with current standards of care for all patients, as well as patient education surrounding safe administration and side effects of the study medications.http://deepblue.lib.umich.edu/bitstream/2027.42/173825/1/13063_2022_Article_6123.pd