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The aim of this study is to experimentally investigate the combustion regime transitions of a single-component kerosene surrogate (n-decane). For this purpose, a deflagration is generated by a spark in a constant-volume vessel with a length-to-width aspect ratio of 4.3. By consuming the unburnt gas, the flame behaves as a piston that compresses the end gas. The pressure and temperature of the end gas increase with the flame propagation until autoignition conditions are reached. Ultrafast schlieren visualizations are set up to monitor the dynamics of the reactive processes, whereas the time-pressure evolution associated with non-dimensional (0D) numerical models is used to characterize the unburnt gas thermodynamic conditions. Once the thermodynamic conditions needed to initiate the autoignition reactions are reached in the end gas, a transition between deflagration (flame speed of approximately ten m/s) and autoignition fronts is observed (propagation velocity ˜200 m/s). This transition occurs for various fuel equivalence ratio values (0.75 – 1). For the strongest thermodynamic conditions, once the velocity of this autoignition front reaches the speed of sound, a new reactive front propagating up to 1800 m/s is observed, thus indicating the transition to detonation combustion mode. Parametric studies indicated that the occurrence of both transitions was a function of the pressure, temperature and equivalence ratio for n-decane fuel. A small initial temperature variation (approximately 40 K) could change the phenomenology of the constant-volume combustion from deflagration to detonation through the autoignition process, even for lean mixtures. The results obtained using our experimental setup show that the transition between autoignition and detonation is due to the acceleration of the autoignition front towards the speed of sound in the unburnt gas. [ABSTRACT FROM AUTHOR]

The canonical diesel spray A is characterized in an optical Rapid Compression Machine (RCM) at high temperature and density conditions (900 K and 850 K, ρ = 23 kg/m3) using simultaneous high-speed OH* chemiluminescence and two-pulse 355 nm Planar Laser Induced Fluorescence (PLIF). The focus is on the time evolution and the repeatability of the early stages of both cool flame and hot ignition phenomena, and on the time evolution of the fluorescing formaldehyde region in between. In particular, time resolved data related to the cool flame are provided. They show the development of several separated kernels on the spray sides at the onset of formaldehyde appearance. Shortly after this phase, the cool flame region expands at high velocity around the kernels and further downstream towards the richer region at the spray head, reaching finally most of the vapor phase region. The position of the first high temperature kernels and their growth are then characterized, with emphasis on the statistics of their location. These time-resolved data are new and they provide further insights into the dynamics of the spray A ignition. They bring some elements on the underlying mechanisms, which will be useful for the validation and improvement of numerical models devoted to diesel spray ignition.

One of the objective of Engine Combustion Network (ECN), (https://ecn.sandia.gov/) is to provide experimental results with high accuracy in order to validate model and reach new steps in scientific understanding of spray combustion at conditions specific to engines. The ECN community defines different target conditions, experimental diagnostics and post processing methods to facilitate the comparison of experimental and simulations studies performed in different facilities or models. In this context two French laboratories propose two new facilities, based on Rapid Compression Machines to reach the ECN spray A conditions. In this paper, the results of liquid and vapour spray penetration as well as Ignition Delay (ID) and Lift-Off Length (LOL) obtained with these Rapid Compression Machines are compared to the results obtained in the Constant Volume Preburn (CVP) vessel of IFPEN. The specificities of each experimental apparatus allow to bring complementary elements of understanding like confinement effects. In non-reactive condition, the liquid and vapour sprays were characterized by Diffused-Back Illumination and Schlieren technique, and in reactive conditions, the LOL and the ID by OH* chemiluminescence. The analysis of the results with regard to the boundary conditions (temperature, velocity, confinement) make it possible to validate these two new facilities and contribute to enhance the database of ECN, highlighting the confinement effect typical of piston engine operation.

The Engine Combustion Network (ECN) community has greatly contributed to improve the fundamental understanding of spray atomization and combustion at conditions relevant to internal combustion engines. In this context, standardized spray experiments have been defined to facilitate the comparison of experimental and simulation studies performed in different facilities and with different models. This operating mode promotes collaborations among research groups and accelerates the advancement of research on spray. In efforts to improve the comparability of the ECN spray A experiments, it is of high importance to review the boundary conditions of different devices used in the community. This work is issued from the collaboration in the ECN France project, where two new experimental facilities from PPRIME (Poitiers) and PRISME (Orleans) institutes are validated to perform spray A experiments. The two facilities, based on Rapid Compression Machine (RCM) design, have been investigated to characterize their boundary conditions (e.g., flow velocity as well as fuel and gas temperatures). A set of standardized spray experiments were performed to compare their results with those obtained in other facilities, in particular the Constant Volume Pre-burn (CVP) vessel at IFPEN. It is noteworthy that it is the first time that RCM type facilities are used in such a way within the ECN. This paper (part 1) focuses on the facilities description and the fine characterization of their boundary conditions. A further paper (part 2) will present the results obtained with the same facilities performing ECN standard spray A characterizations. The reported review of thermocouple thermometry highlights that it is necessary to use thin-wires and bare-bead junction as small as possible. This would help to measure the temperature fluctuations with a minimal need for error corrections, which are highly dependent on the proper estimation of the velocity through the junction, and therefore it may introduce important uncertainties. Temperature heterogeneities are observed in all spray A devices. The standard deviation of the temperature distribution at the time of injection is approximately 5%. We report time-resolved temperature measurement from PPRIME RCM, performed in the near nozzle area during the injection. In inert condition, colder gases from the boundary layer are entrained toward the mixing area of the spray causing a further deviation from the target temperature. This emphasizes the importance of the temperature in the boundary (wall) layer. In reacting condition, the temperature of these entrained gases increases by the effect of the increased pressure, as the RCM has a relatively small volume. Generally, the velocity and turbulence levels are an order of magnitude higher in RCM and constant pressure flow compared to CVP vessels. The boundary characterization presented here will be the base for discussing spray behavior in the part 2 of this paper.

Cibenzoline is a new antiarrhythmic agent with class 1 properties, and additional class 3 and 4 effects. We treated 28 patients with drug-refractory and recurrent ventricular tachycardia with up to 700 mg/day cibenzoline for periods up to 5-5 months. Cibenzoline prevented the recurrence of ventricular tachycardia in five patients (18%). In three patients (11%) the arrhythmia may have been worsened, in 23 patients (82%) cibenzoline was ineffective. Cibenzoline increased the PR interval by 18% and the QRS duration by 33%; the effect on the QT was variable and the corrected QT interval did not change significantly. Side-effects were observed in 21% of patients. We conclude that cibenzoline does not appear to be superior to conventional class I antiarrhythmic agents and that it cannot be recommended for general use in patients with ventricular tachycardia. Additional pharmacokinetic and electrophysiologic studies are required before cibenzoline is used in outpatients with severe ventricular arrhythmias. [ABSTRACT FROM PUBLISHER]

Importance: A multicenter randomized clinical trial (RCT) showed a lung recruitment maneuver using high-frequency oscillatory ventilation just before surfactant administration (ie, intubate-recruit-surfactant-extubate [IN-REC-SUR-E]) improved the efficacy of treatment compared with the standard intubate-surfactant-extubate (IN-SUR-E) technique without increasing the risk of adverse neonatal outcomes., Objective: To examine follow-up outcomes at corrected postnatal age (cPNA) 2 years of preterm infants previously enrolled in an RCT and treated with IN-REC-SUR-E or IN-SUR-E in 35 tertiary neonatal intensive care units., Design, Setting, and Participants: This was a follow-up study of infants recruited into the primary RCT from 2015 to 2018 at 35 tertiary neonatal intensive care units (NICUs) in Italy. Follow-up examinations included neurodevelopmental, growth, and respiratory outcomes of these children at cPNA 2 years. Participants included spontaneously breathing extremely preterm neonates (24 0/7 to 27 6/7 weeks' gestation) reaching failure criteria for continuous positive airway pressure within the first 24 hours of life. Data were analyzed from April 2023 to January 2024., Intervention: Infants were randomly assigned (1:1) to IN-REC-SUR-E or IN-SUR-E and then followed up., Main Outcomes and Measures: The primary outcome was the occurrence of death after discharge or major disability at cPNA 2 years. Secondary outcomes were neurodevelopmental outcomes (major disability, cerebral palsy, cognitive impairment, visual deficit, or auditory deficit), anthropometric measurements (weight, length, and head circumference), and recurrent respiratory infections and hospitalizations because of respiratory causes at 2y cPNA., Results: A total of 137 extremely preterm infants (median [IQR] gestational age, 26.5 [25.3-27.5] weeks and 75 [54.7%] female), initially enrolled in the original RCT, were followed up at cPNA 2 years, including 64 infants in the IN-SUR-E group and 73 infants in the IN-REC-SUR-E group. There were no significant differences in the occurrence of death after discharge or major disability at cPNA 2 years (IN-SUR-E: 13 children [20.3%] vs IN-REC-SUR-E: 10 children [13.7%]; P = .36). There were no significant differences in incidence of disability, cerebral palsy, or cognitive impairment in the IN-REC-SUR-E group compared with the IN-SUR-E group. There were no significant differences in anthropometric measurements (weight, length, and head circumference) between groups. There were no significant differences in the incidence of recurrent respiratory infections or in hospitalizations because of respiratory causes between groups., Conclusions and Relevance: In this RCT of lung recruitment before surfactant vs standard care there were no significant differences between the 2 groups in death, neurodevelopmental outcomes, anthropometric measurements, or recurrent respiratory infections at the 2-year follow-up. These findings can aid clinicians in decision-making for the best strategy to administer surfactant, considering long-term outcomes.

Objectives: The measurement of blood pH and gas analytes (BPGA), soon after birth, constitutes the first-line standard of care procedure in high-risk newborns. However, no data is available in capillary blood on perinatal bias such as gestational age (GA), weight at birth (BW), delivery mode, and gender. The aims of the present study were to investigate whether in a cohort of healthy preterm (PT) and term (T) infants BPGA were GA, BW, delivery mode and gender dependent, thus affecting BPGA reliability as diagnostic test., Methods: We performed a prospective case-control study in 560 healthy infants (PT: n=115, T: n=445). BPGA was measured within 24-h from birth. Perinatal characteristics, outcomes, and clinical examination were also recorded., Results: PT infants showed higher (p<0.001) carbon dioxide partial pressure (pCO 2 ), fraction of fetal hemoglobin (HbF), base excess (BE), bicarbonate (HCO 3 ), and lower lactate (Lac) levels. When corrected for delivery mode, higher (p<0.001) HbF, BE, HCO 3 , and lower Lac levels were found. Similarly, higher (p<0.05, for all) pCO 2 , HbF, BE, HCO 3 and lower Lac levels were found between female and male PT and T infants. Repeated multiple logistic regression analysis showed that BPGA was GA, BW, delivery mode and gender dependent., Conclusions: The present results showing that BPGA can be affected by a series of perinatal outcomes open the way to further investigations providing longitudinal BPGA reference curves in the transitional phase, thus empowering BPGA role as a reliable diagnostic and therapeutic strategies efficacy marker., (© 2024 Walter de Gruyter GmbH, Berlin/Boston.)

Aim: To investigate the effects of caffeine loading/maintenance administration on near-infrared spectroscopy cerebral, kidney and splanchnic patterns in preterm infants., Methods: We conducted a multicentre case-control prospective study in 40 preterm infants (gestational age 29 ± 2 weeks) where each case acted as its own control. A caffeine loading dose of 20 mg/kg and a maintenance dose of 5 mg/kg after 24 h were administered intravenously. Near infrared spectroscopy monitoring parameters were monitored 30 min before, 30 min during and 180 min after caffeine therapy administration., Results: A significant increase (p < 0.05) in splanchnic regional oxygenation and tissue function and a decrease (p < 0.05) in cerebral tissue function after loading dose was shown. A preferential hemodynamic redistribution from cerebral to splanchnic bloodstream was also observed. After caffeine maintenance dose regional oxygenation did not change in the monitored districts, while tissue function increased in kidney and splanchnic bloodstream., Conclusion: Different caffeine administration modalities affect cerebral/systemic oxygenation status, tissue function and hemodynamic pattern in preterm infants. Future studies correlating near infrared spectroscopy parameters and caffeine therapy are needed to determine the short/long-term effect of caffeine in preterm infants., (© 2023 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.)

Perioperative stress detection in children with congenital heart disease (CHD), particularly in the brain, is still limited. Among biomarkers, γ-amino-aminobutyric acid (GABA) assessment in biological fluids appears to be promising for its regulatory action on the cardiovascular and cerebral systems. We aimed to investigate cyanotic (C) or non-cyanotic (N) CHD children for GABA blood level changes in the perioperative period. We conducted an observational study in 68 CHD infants (C: n = 33; N: n = 35) who underwent perioperative clinical, standard laboratory and monitoring parameter recordings and GABA assessment. Blood samples were drawn at five predetermined time-points before, during and after surgery. No significant perioperative differences were observed between groups in clinical and laboratory parameters. In C, perioperative GABA levels were significantly lower than N. Arterial oxygen saturation and blood concentration significantly differed between C and N children and correlated at cardiopulmonary by-pass (CPB) time-point with GABA levels. The present data showing higher hypoxia/hyperoxia-mediated GABA concentrations in C children suggest that they are more prone to perioperative cardiovascular and brain stress/damage. The findings suggest the usefulness of further investigations to detect the "optimal" oxygen concentration target in order to avoid the side effects associated with re-oxygenation during CPB.

Objectives: The early detection of preterm infants (PI) at risk for intraventricular hemorrhage (IVH) and neurological sequelae still constitutes an unsolved issue. We aimed at validating the role of S100B protein in the early diagnosis and prognosis of IVH in PI by means of cerebral ultrasound (CUS) and magnetic resonance imaging (MRI) today considered standard of care procedures., Methods: We conducted an observational case-control study in 216 PI of whom 36 with IVH and 180 controls. Standard clinical, laboratory, radiological monitoring procedures and S100B urine measurement were performed at four time-points (first void, 24, 48, 96 h) after birth. Cerebral MRI was performed at 40-42 weeks of corrected gestational age., Results: Elevated (p<0.001, for all) S100B levels were observed in the IVH group at all monitoring time-point particularly at first void when standard monitoring procedures were still silent or unavailable. S100B measured at first void correlated (p<0.001) with the grade of hemorrhage by means of CUS and with the site and extension of neurological lesion (p<0.001, for all) as assessed by MRI., Conclusions: The present results showing a correlation among S100B and CUS and MRI offer additional support to the inclusion of the protein in clinical daily management of cases at risk for IVH and adverse neurological outcome. The findings open the way to further investigations in PI aimed at validating new neurobiomarkers by means of S100B., (© 2021 Walter de Gruyter GmbH, Berlin/Boston.)

Background: Provisional T-stenting (PS) is generally recommended to treat patients with coronary bifurcation disease (CBD) percutaneously, but PS may not fit all complex bifurcation anatomies. Therefore, several types of up-front 2-stent techniques have been described. We aimed to identify the best percutaneous coronary intervention (PCI) technique to manage patients with CBD., Methods: We systematically reviewed randomized controlled trials (RCTs) including patients undergoing CBD PCI which included several types of PCI techniques-PS, double-kissing (DK) crush, T-stenting and protrusion, culotte, dedicated bifurcation stents, crushing, and T-stenting-and we compared device-oriented clinical events (DOCEs), a composite of cardiac death, target-vessel myocardial infarction, stent thrombosis, and target-lesion or target-vessel revascularization, in a network meta-analysis. We included 26 RCTs, leading to a pooled population of 10,339 patient-years and a total of 1229 DOCEs., Results: The DK-crush technique was associated with the lowest DOCE rate, with a relative risk of 0.62 (95% CI 0.42-0.92) compared with the PS technique. DK-crush had the highest probability (model likelihood 90.2%, area under the cumulative ranking curve 98.0%) of being the best technique among those explored to reduce DOCEs in patients receiving CBD PCI., Conclusions: When a 2-stent strategy is considered in a patient with CBD, the DK-crush technique reduces DOCEs compared with other bifurcation techniques based on all available RCTs., (Copyright © 2019 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.)

The term stunned myocardium is used to indicate a reversible post-ischemic dysfunction of the ventricular mechanism which may persist for hours, days or weeks after the restoration of coronary flow following spontaneous or pharmacological thrombolysis, transluminal coronary angioplasty, aorto-coronary bypass and ischemic attacks. Hibernating myocardium is used to describe a depression of ventricular contractility in the presence of chronic hypoperfusion which may be reversed following revascularization as a result of aorto-coronary by-pass surgery. Three biochemical and physiopathological hypotheses are currently acknowledged to explain the phenomenon of stunning: the hypothesis of free oxygen radicals, the hypothesis related to an energy deficit and that involving a calcium overload. It is possible that oxydizing stress induced by free radicals may modify the activity of one or more sarcolemmic proteins which regulate the flow of calcium or other ions. Alterations in the transport and accumulation of calcium ions due to a Na+/Ca++ pump deficit and calcium-ATPase of the sarcoplasmatic reticle appear to be responsible for contractile dysfunction. The hypothesis concerning an energy deficit appears to be least probable since even if ATP levels are low the intracellular energy status does not appear to be a factor which limits mechanical function which may be stimulated in the absence of further variations in the content of highly energetic phosphates. There is also reduced myofibrillar creatinkinase activity. In hibernating myocardium the mechanical dysfunction is due to a metabolic and therefore contractile "down-regulation' with low myocardial energy and oxygen consumption to ensure the survival of chronically hypoperfused areas.(ABSTRACT TRUNCATED AT 250 WORDS)