The potential of catalysed exhaust gas recirculation to improve high-load operation in spark ignition engines

Within the literature, there are a number of studies investigating the benefits of exhaust gas recirculation, and as a result it has become established as a promising technology for combustion control to allow engine downsizing technology to be advanced. Aside from the dilution effect of exhaust gas recirculation, some of the components, such as NO, CO, and hydrocarbons, can have significant chemical effects. The literature shows that the component within exhaust gas recirculation which has the largest chemical effect on combustion is NO, which can promote or inhibit the onset of autoignition causing reactions within the end gas at high load. The reduction in NOx gases in catalysed exhaust gas recirculation can increase the knock limit at high load, with some authors reporting up to a 5∘ crank angle improvement in combustion phasing. There is conflicting evidence on whether this translates to an improvement in fuel consumption, with one study finding a decrease of up to 2% comparing to another finding an increase of 1.5%-3.5%. Crude calculations on the emissions of a 2.0-L direct injection spark ignition engine operating at high load show that in an extreme case the reduction in the calorific value of the inlet charge due to catalysis of the recirculated gases can be up to 4.5%. Despite the potential benefits, the literature on catalysed exhaust gas recirculation is fairly limited and the evidence seems so far inconclusive as to whether this technology may have the potential to further enhance the benefits of exhaust gas recirculation. This article uses current literature to ascertain the potential benefits of catalysed exhaust gas recirculation, compare to pre-catalyst exhaust gas recirculation, and investigates its individual components in more detail to explain how chemical interactions can either promote or inhibit ignition depending on their concentration and temperature. </jats:p

Ethical duties of nephrologists:when patients are nonadherent to treatment

When providing care, nephrologists are subject to various ethical duties. Beyond the Hippocratic notion of doing no harm, nephrologists also have duties to respect their patients' autonomy and dignity, to meet their patients' care goals in the least invasive way, to act impartially, and, ultimately, to do what is (clinically) beneficial for their patients. Juggling these often-conflicting duties can be challenging at the best of times, but can prove especially difficult when patients are not fully adherent to treatment. When a patient's nonadherence begins to cause harm to themselves and/or others, it may be questioned whether discontinuation of care is appropriate. We discuss how nephrologists can meet their ethical duties when faced with nonadherence in patients undergoing hemodialysis, including episodic extreme agitation, poor renal diet, missed hemodialysis sessions, and emergency presentations brought on by nonadherence. Furthermore, we consider the impact of cognitive impairment and provider-family conflict when making care decisions in a nonadherence context, as well as how the coronavirus disease 2019 pandemic might affect responses to nonadherence. Suggestions are provided for ethically informed responses, prioritizing a patient-narrative approach that is attentive to patients' values and preferences, multidisciplinarity, and the use of behavioral contracts and/or technology where appropriate

Neighbourhood cohesion and mental wellbeing among older adults:A mixed methods approach

There is now a body of evidence that demonstrates strong links between neighbourhood characteristics and mental health and wellbeing. There is an increasing interest in how this relationship varies for individuals of different ages. Understanding the link between neighbourhood and wellbeing for older adults is of particular significance, given the changing age structure of the population and the desire among policy makers and practitioners to promote healthy and active ageing. This paper provides further evidence on the nature and strength of the link between individual perceptions of neighbourhood belonging and mental wellbeing among those over age fifty using both qualitative and quantitative data from three British cohort studies. Between 2008 and 2011 quantitative data were collected from 10,312 cohort members, and 230 of them took part in qualitative biographical interviews.Quantitative analysis confirms that there is a moderate association between neighbourhood cohesion and wellbeing measured at the individual level in each of the three cohorts. This association persists after controlling for a range of covariates including personality. The association between neighbourhood cohesion and wellbeing is stronger for individuals in the older two cohorts than in the younger cohort.Using qualitative biographical interviews with 116 men and 114 women we illustrate how individuals talk about their sense of neighbourhood belonging. The importance of social participation as a mechanism for promoting neighbourhood belonging, and the use of age and life stage as characteristics to describe and define neighbours, is clear. In addition, the qualitative interviews point to the difficulties of using a short battery of questions to capture the varied and multi-dimensional nature of neighbourhood relations.<br/

The effect of high dose antibiotic impregnated cement on rate of surgical site infection after hip hemiarthroplasty for fractured neck of femur : a protocol for a double-blind quasi randomised controlled trial

Background: Mortality following hip hemiarthroplasty is in the range of 10-40% in the first year, with much attributed to post-operative complications. One such complication is surgical site infection (SSI), which at the start of this trial affected 4.68% of patients in the UK having this operation. Compared to SSI rates of elective hip surgery, at less than 1%, this figure is elevated. The aim of this quasi randomised controlled trial (RCT) is to determine if high dose antibiotic impregnated cement can reduce the SSI in patients at 12-months after hemiarthroplasty for intracapsular fractured neck of femur. Methods: 848 patients with an intracapsular fractured neck of femur requiring a hip hemiarthroplasty are been recruited into this two-centre double-blind quasi RCT. Participants were recruited before surgery and quasi randomised to standard care or intervention group. Participants, statistician and outcome assessors were blind to treatment allocation throughout the study. The intervention consisted of high dose antibiotic impregnated cement consisting of 1 gram Clindamycin and 1 gram of Gentamicin. The primary outcome is Health Protection Agency (HPA) defined deep surgical site infection at 12 months. Secondary outcomes include HPA defined superficial surgical site infection at 30 days, 30 and 90-day mortality, length of hospital stay, critical care stay, and complications. Discussion: Large randomised controlled trials assessing the effectiveness of a surgical intervention are uncommon, particularly in the speciality of orthopaedics. The results from this trial will inform evidence-based recommendations for antibiotic impregnated cement in the management of patients with a fractured neck of femur undergoing a hip hemiarthroplasty. If high dose antibiotic impregnated cement is found to be an effective intervention, implementation into clinical practice could improve long-term outcomes for patients undergoing hip hemiarthroplasty

Structure-based design of nucleoside-derived analogues as sulfotransferase inhibitors

Sulfotransferases (STs) catalyse the transfer of a sulfonyl group (‘sulfation’) from the enzyme co-factor 3ʹ-phosphoadenosine 5ʹ-phosphosulfate (PAPS) to a variety of biomolecules. Tyrosine sulfation of proteins and carbohydrate sulfation play a crucial role in many protein-protein interactions and cell signalling pathways in the extracellular matrix. This is catalysed by several membrane-bound STs, including tyrosylprotein sulfotransferase 1 (TPST1) and heparan sulfate 2-O-sulfotransferase (HS2ST1). Recently, involvement of these enzymes and their post-translational modifications in a growing number of disease areas has been reported, including inflammation, cancer and Alzheimer’s disease. Despite their growing importance, the development of small molecules to probe the biological effect of TPST and carbohydrate ST inhibition remains in its infancy. We have used a structure-based approach and molecular docking to design a library of adenosine 3',5'-diphosphate (PAP) and PAPS mimetics based upon 2'-deoxyadenosine and using 2'-deoxy-PAP as a benchmark. The use of allyl groups as masked methyl esters was exploited in the synthesis of PAP-mimetics, and click chemistry was employed for the divergent synthesis of a series of PAPS-mimetics. A suite of in vitro assays employing TPST1 and HS2ST, and a kinase counter screen, were used to evaluate inhibitory parameters and relative specificity for the STs

Early ultrasound surveillance of newly-created haemodialysis arteriovenous fistula

IntroductionWe assess if ultrasound surveillance of newly-created arteriovenous fistulas (AVFs) can predict nonmaturation sufficiently reliably to justify randomized controlled trial (RCT) evaluation of ultrasound-directed salvage intervention.MethodsConsenting adults underwent blinded fortnightly ultrasound scanning of their AVF after creation, with scan characteristics that predicted AVF nonmaturation identified by logistic regression modeling.ResultsOf 333 AVFs created, 65.8% matured by 10 weeks. Serial scanning revealed that maturation occurred rapidly, whereas consistently lower fistula flow rates and venous diameters were observed in those that did not mature. Wrist and elbow AVF nonmaturation could be optimally modeled from week 4 ultrasound parameters alone, but with only moderate positive predictive values (PPVs) (wrist, 60.6% [95% confidence interval, CI: 43.9–77.3]; elbow, 66.7% [48.9–84.4]). Moreover, 40 (70.2%) of the 57 AVFs that thrombosed by week 10 had already failed by the week 4 scan, thus limiting the potential of salvage procedures initiated by that scan’s findings to alter overall maturation rates. Modeling of the early ultrasound characteristics could also predict primary patency failure at 6 months; however, that model performed poorly at predicting assisted primary failure (those AVFs that failed despite a salvage attempt), partly because patency of at-risk AVFs was maintained by successful salvage performed without recourse to the early scan data.ConclusionEarly ultrasound surveillance may predict fistula maturation, but is likely, at best, to result in only very modest improvements in fistula patency. Power calculations suggest that an impractically large number of participants (>1700) would be required for formal RCT evaluation