CFD analysis of the fuel-air mixture formation process in passive prechambers for use in a high-pressure direct injection (HPDI) Two-stroke engine

The research on two-stroke engines has been focused lately on the development of direct injection systems for reducing the emissions of hydrocarbons by minimizing the fuel shortcircuiting. Low temperature combustion (LTC) may be the next step to further improve emissions and fuel consumption; however, LTC requires unconventional ignition systems. Jet ignition, i.e., the use of prechambers to accelerate the combustion process, turned out to be an effective way to perform LTC. The present work aims at proving the feasibility of adopting passive prechambers in a high-pressure, direct injection, two-stroke engine through non-reactive computational fluid dynamics analyses. The goal of the analysis is the evaluation of the prechamber performance in terms of both scavenging efficiency of burnt gases and fuel/air mixture formation inside the prechamber volume itself, in order to guarantee the mixture ignitability. Two prechamber geometries, featuring different aspect ratios and orifice numbers, were investigated. The analyses were replicated for two different locations of the injection and for three operating conditions of the engine in terms of revolution speed and load. Upon examination of the results, the effectiveness of both prechambers was found to be strongly dependent on the injection setup

Neuroleptanalgesia for acute abdominal pain: a systematic review

Background: Acute abdominal pain (AAP) comprises up to 10% of all emergency department (ED) visits. Current pain management practice is moving toward multi-modal analgesia regimens that decrease opioid use. Objective: This project sought to determine whether, in patients with AAP (population), does administration of butyrophenone antipsychotics (intervention) compared to placebo, usual care, or opiates alone (comparisons) improve analgesia or decrease opiate consumption (outcomes)? Methods: A structured search was performed in Cochrane CENTRAL, CINAHL, Database of Abstracts of Reviews of Effects, Directory of Open Access Journals, Embase, IEEE-Xplorer, Latin American and Caribbean Health Sciences Literature, Magiran, PubMed, Scientific Information Database, Scopus, TÜBİTAK ULAKBİM, and Web of Science. Clinical trial registries (ClinicalTrials.gov, World Health Organization International Clinical Trials Registry Platform, and Australian New Zealand Clinical Trials Registry), relevant bibliographies, and conference proceedings were also searched. Searches were not limited by date, language, or publication status. Studies eligible for inclusion were prospective randomized clinical trials enrolling patients (age ≥18 years) with AAP treated in acute care environments (ED, intensive care unit, postoperative). The butyrophenone must have been administered either intravenously or intramuscularly. Comparison groups included placebo, opiate only, corticosteroids, non-steroidal anti-inflammatory drugs, or acetaminophen. Results: We identified 7,217 references. Six studies met inclusion criteria. One study assessed ED patients with AAP associated with gastroparesis, whereas five studies assessed patients with postoperative AAP: abdominal hysterectomy (n=4), sleeve gastrectomy (n=1). Three of four studies found improvements in pain intensity with butyrophenone use. Three of five studies reported no change in postoperative opiate consumption, while two reported a decrease. One ED study reported no change in patient satisfaction, while one postoperative study reported improved satisfaction scores. Both extrapyramidal side effects (n=3) and sedation (n=3) were reported as unchanged. Conclusion: Based on available evidence, we cannot draw a conclusion on the efficacy or benefit of neuroleptanalgesia in the management of patients with AAP. However, preliminary data suggest that it may improve analgesia and decrease opiate consumption

Transesophageal echocardiography for the investigation of right ventricular kinesis: Preliminary experience in patients with normal right ventricle or previous inferior myocardial infarction | [L'ECOCARDIOGRAFIA TRANSESOFAGEA PER LO STUDIO DELLA CINESI DEL VENTRICOLO DESTRO NORMALE E DOPO INFARTO MIOCARDICO INFERIORE: PROBLEMI ATTUALI E PROSPETTIVE]

The evaluation of right ventricular kinesis by two-dimensional transthoracic echocardiography represents a difficult task. This technique can visualize the right ventricle in several projections, but the image quality and the variability of imaging views usually do not allow quantitative analysis. In this study, we investigated the potential of 'panoramic' transesophageal echocardiography for evaluating ventricular global and regional kinesis. In 53 controls and in 17 patients with previous inferior myocardial infarction and asynergy involving the inferior wall of both ventricles. Good-quality images of at least one horizontal section of the right ventricle were obtained in 81.4% of subjects by conventional (90°) sector in 100% of subjects through a wide-angle (270°) sector. Images of the right ventricle in short-axis view at medium level were acquired and evaluated in 91.4% of cases, but at basal and apical levels only in 65.7% and 37.1%, respectively. The low percentage of successful detection and evaluation of the right ventricle at apical level can be explained by the prominent motion and trabeculation of the apex. Global systolic area changes in controls attained similar values at apical and medium levels (56% and 55%, respectively), but were significantly lower (48%, p < 0.05) at basal level. In patients with previous inferior myocardial infarction and inferoposterior asynergy, global systolic area changes were significantly (p < 0.01) lower at medium and basal levels (32% and 27%, respectively) compared with controls. The regional kinesis of the right ventricle was assessed as segmental systolic area changes in 12 different segments, by both fixed and float system of center of cavity. In controls, the fixed system underestimated the kinesis of inferior and septal segments and overestimated the kinesis of anterolateral segments, due to a leftward translation and inferior rotation of the right ventricle during systole. The float system showed an almost concentric kinesis of the right ventricle, with segmental systolic area changes ranging between 52% and 66%. In patients with right ventricular asynergy, the fixed system confirmed the 'eyeball' analysis, while the float system tended to mask the asynergy and showed a more uniform kinesis, with diffuse decrement in systolic area changes throughout all segments. Further evaluation, also by biplane and omniplane probes, may help to overcome the limitations of the present method for a comprehensive analysis of right ventricular kinesis. As compared to the transthoracic approach, transesophageal echocardiography, however, already allows to improve the echocardiographic assessment of right ventricular kinesis and appears to be a promising tool, and potentially a reference technique, for the investigation of right ventricular kinesis during stress