Combustion of n-C3-C6 Linear Alcohols: An Experimental and Kinetic Modeling Study. Part I: Reaction Classes, Rate Rules, Model Lumping, and Validation.

This work (and the companion paper, Part II) presents new experimental data for the combustion of n-C3-C6 alcohols (n-propanol, n-butanol, n-pentanol, n-hexanol) and a lumped kinetic model to describe their pyrolysis and oxidation. The kinetic subsets for alcohol pyrolysis and oxidation from the CRECK kinetic model have been systematically updated to describe the pyrolysis and high- and low-temperature oxidation of this series of fuels. Using the reaction class approach, the reference kinetic parameters have been determined based on experimental, theoretical, and kinetic modeling studies previously reported in the literature, providing a consistent set of rate rules that allow easy extension and good predictive capability. The modeling approach is based on the assumption of an alkane-like and alcohol-specific moiety for the alcohol fuel molecules. A thorough review and discussion of the information available in the literature supports the selection of the kinetic parameters that are then applied to the n-C3-C6 alcohol series and extended for further proof to describe n-octanol oxidation. Because of space limitations, the large amount of information, and the comprehensive character of this study, the manuscript has been divided into two parts. Part I describes the kinetic model as well as the lumping techniques and provides a synoptic synthesis of its wide range validation made possible also by newly obtained experimental data. These include speciation measurements performed in a jet-stirred reactor (p = 107 kPa, T = 550-1100 K, φ = 0.5, 1.0, 2.0) for n-butanol, n-pentanol, and n-hexanol and ignition delay times of ethanol, n-propanol, n-butanol, n-pentanol/air mixtures measured in a rapid compression machine at φ = 1.0, p = 10 and 30 bar, and T = 704-935 K. These data are presented and discussed in detail in Part II, together with detailed comparisons with model predictions and a deep kinetic discussion. This work provides new experimental targets that are useful for kinetic model development and validation (Part II), as well as an extensively validated kinetic model (Part I), which also contains subsets of other reference components for real fuels, thus allowing the assessment of combustion properties of new sustainable fuels and fuel mixtures.

Combustion of n-C3-C6 Linear Alcohols: An Experimental and Kinetic Modeling Study. Part II: Speciation Measurements in a Jet-Stirred Reactor, Ignition Delay Time Measurements in a Rapid Compression Machine, Model Validation, and Kinetic Analysis.

This work presents new experimental data for n-C3-C6 alcohol, combustion (n-propanol, n-butanol, n-pentanol, n-hexanol). Speciation measurements have been carried out in a jet-stirred reactor (p = 107 kPa, T = 550-1100 K, φ = 0.5, 1.0, 2.0) for n-butanol, n-pentanol, and n-hexanol. Ignition delay times of ethanol, n-propanol, n-butanol, and n-pentanol/air mixtures were measured in a rapid compression machine at φ = 1.0, p = 10 and 30 bar, and T = 704-935 K. The kinetic subsets for alcohol pyrolysis and oxidation from the CRECK kinetic model have been systematically updated to describe the pyrolysis and high- and low-temperature oxidation of this series of fuels as described in Part I of this work (Pelucchi M.; Namysl S.; Ranzi E.Combustion of n-C3-C6 linear alcohol: an experimental and kinetic modeling study. Part I: reaction classes, rate rules, model lumping and validation. Submitted to Energy and Fuels, 2020). Part II describes in detail the facilities used for this systematic experimental investigation of n-C3-C6 alcohol combustion and presents a complete validation of the kinetic model by means of comparisons with the new data and measurements previously reported in the literature for both pyrolytic and oxidative conditions. Kinetic analyses such as rate of production and sensitivity analyses are used to highlight the governing reaction pathways and reasons for existing deviations, motivating possible further improvements in our chemistry mechanism.

Hyphal network whole field imaging allows for accurate estimation of anastomosis rates and branching dynamics of the filamentous fungus Podospora anserina.

The success of filamentous fungi in colonizing most natural environments can be largely attributed to their ability to form an expanding interconnected network, the mycelium, or thallus, constituted by a collection of hyphal apexes in motion producing hyphae and subject to branching and fusion. In this work, we characterize the hyphal network expansion and the structure of the fungus Podospora anserina under controlled culture conditions. To this end, temporal series of pictures of the network dynamics are produced, starting from germinating ascospores and ending when the network reaches a few centimeters width, with a typical image resolution of several micrometers. The completely automated image reconstruction steps allow an easy post-processing and a quantitative analysis of the dynamics. The main features of the evolution of the hyphal network, such as the total length L of the mycelium, the number of "nodes" (or crossing points) N and the number of apexes A, can then be precisely quantified. Beyond these main features, the determination of the distribution of the intra-thallus surfaces (Si) and the statistical analysis of some local measures of N, A and L give new insights on the dynamics of expanding fungal networks. Based on these results, we now aim at developing robust and versatile discrete/continuous mathematical models to further understand the key mechanisms driving the development of the fungus thallus.

Systematic gene deletion and functional characterization of histidine kinase phosphorelay receptors (HKRs) in the human pathogenic fungus Aspergillus fumigatus.

Histidine kinase receptors (HKRs) appear to be a common strategy for model and pathogenic fungi to sense and respond to environmental stresses. In the human pathogen Aspergillus fumigatus, which is responsible for invasive aspergillosis, 13 genes potentially encoding HKRs have been identified. Until now, only three HKRs have been functionally characterized. The aim of this study was to perform the systematic invalidation of A. fumigatus HKR genes and the careful phenotypic characterization of the relevant mutants. This study notably allowed to gain new important insights into the role of HKRs in physiology of A. fumigatus. Actually, we showed that (i) NikA/TcsC could be involved in the cell wall integrity pathway, (ii) Fhk6 and PhkA were involved in the regulation of the "fluffy" developmental program, (iii) PhkB could participate in the regulation of conidiation and (iv) PhkA was implied in the resistance of oxidative stresses.

[Propranolol and lactatemia during hypovolemic shock: a case report]. / Propranolol et lactatémie durant un choc hypovolémique non septique : à propos d'une observation.

Lactate production results from anaerobic glycolysis. This pathway is recruited physiologically during intense and sustained muscular contractions. Hyperlactatemia may develop when tissue oxygenation is jeopardized such as in shock, its absence having been, however, sometimes reported in sepsis in which interactions between infectious agents and the organism's cells might blunt or disrupt hyperlactatemia development. During the course of acute rotavirus gastroenteritis, a 9-month-old girl developed severe dehydration (capillary-refill time, 5 s) leading to hypovolemic shock without signs of sepsis and with hypotension at 62/21 mmHg Surprisingly, the child failed to develop hyperlactatemia during shock. An etiologic search to understand why hyperlactatemia did not occur revealed that this patient had been receiving propranolol since the age of four months for the treatment of a Cyrano hemangioma. Via its inhibitory action on ß-adrenergic receptors, propranolol antagonizes the stimulation of glycolysis by catecholamines, which may be rationally proposed to have contributed to preventing hyperlactatemia during hypovolemic shock in this patient. Mechanisms by which propranolol can mediate this antihyperlactatemia action are further illustrated and discussed.

An experimental study of the structure of laminar premixed flames of ethanol/methane/oxygen/argon.

The structures of three laminar premixed stoichiometric flames at low pressure (6.7 kPa): a pure methane flame, a pure ethanol flame and a methane flame doped by 30% of ethanol, have been investigated and compared. The results consist of concentration profiles of methane, ethanol, O2, Ar, CO, CO2, H2O, H2, C2H6, C2H4, C2H2, C3H8, C3H6, p-C3H4, a-C3H4, CH2O, CH3HCO, measured as a function of the height above the burner by probe sampling followed by on-line gas chromatography analyses. Flame temperature profiles have been also obtained using a PtRh (6%)-PtRh (30%) type B thermocouple. The similarities and differences between the three flames were analyzed. The results show that, in these three flames, the concentration of the C2 intermediates is much larger than that of the C3 species. In general, mole fraction of all intermediate species in the pure ethanol flame is the largest, followed by the doped flame, and finally the pure methane flame.

Detailed product analysis during low- and intermediate-temperature oxidation of ethylcyclohexane.

An experimental study of the oxidation of ethylcyclohexane has been performed in a jet-stirred reactor with online gas chromatography, under quasi-atmospheric pressure (800 Torr), at temperatures ranging from 500 to 1100 K (low- and intermediate-temperature zone including the negative temperature coefficient area), at a residence time of 2 s, and for three equivalence ratios (0.25, 1, and 2). Ethylcyclohexane displays important low-temperature reactivity with a well-marked negative temperature coefficient behavior. In addition to 47 products with a mass lower than ethylcyclohexane which have been quantified, many species with a C(8)H(14)O formula (molecular weight of 126) were detected by GC-MS and 7 of them were quantified. These molecules are cyclic ethers, ketones, and aldehydes with the same carbon skeleton as the reactant. Experiments were also carried on under the same conditions for two other C(8) hydrocarbons, n-octane and 1-octene, showing that the reactivity of ethylcyclohexane is close to that of the alkene and lower than that of the alkane. Simulations using a detailed kinetic model of the literature allow a good prediction of the global reactivity and of the main hydrocarbon products for temperatures above 800 K. The main reaction channels leading to the observed reaction products at both low (below 800 K) and intermediate temperature (above 800 K) are discussed.

Noradrenaline use for septic shock in children: doses, routes of administration and complications.

AIM: To report our 10 year experience with noradrenaline use in children with septic shock focusing on doses, routes of administration and complications. METHODS: Retrospective single-centre review of children with septic shock who received noradrenaline between 2000 and 2010. RESULTS: We identified 144 children with septic shock treated with noradrenaline, in 22% as the first-line drug. The median volume resuscitation before vasoactive agent administration was 50 mL/kg interquartile range [IQR: 30-70]. Mean doses of noradrenaline ranged from 0.5 ± 0.4 µg/kg per min (starting dose) to 2.5 ± 2.2 µg/kg per min (maximum dose). Noradrenaline was administered via peripheral venous access or intra-osseous route in 19% of cases for a median duration of 3 h [IQR: 2-4] without any adverse effects. The use of noradrenaline increased over the study period. Mortality rate was 45% with a significant decrease over the study period. Adverse effects included arrhythmia in two children and hypertension in eight children. None of these arrhythmias required treatment and hypertension resolved with the noradrenaline dose reduction. CONCLUSION: Higher doses of noradrenaline than those suggested in the literature may be necessary to reverse hypotension and hypoperfusion. The use of noradrenaline through peripheral venous access or intra-osseous route was safe, without any adverse effects.

[Two children with cerebral and retinal hemorrhages: do not diagnose shaken baby syndrome too rapidly]. / Association hémorragies cérébrales et rétiniennes chez 2 enfants : ne pas conclure trop vite au diagnostic d'enfant secoué.

We report on 2 cases associating retinal (RH) and cerebral hemorrhages (CH), which first suggested the diagnosis of shaken baby syndrome (SBS). After an etiologic search, the diagnosis was corrected: the first case was a late hemorrhagic disease of the newborn and the second case hemophilia A. RH is a major feature of SBS, although not pathognomonic. There is no specific RH of SBS but they usually affect the posterior retinal pole. Typically, RHs of SBS are present in both eyes, although unilateral RHs do not exclude the diagnosis of SBS. The relationship between RH and CH has been reported in SBS but also in other diseases. Thus, one must search for hemostasis abnormalities, even though the clinical presentation suggests SBS. Ignoring SBS as well as coming to the conclusion of SBS too quickly should be avoided. Diagnostic difficulties may be related to the number of physicians involved and their interpretation of the facts. These 2 cases underline the need for working as a team that includes hematologists able to interpret coagulation parameters.

JTHERGAS: Thermodynamic Estimation from 2D Graphical Representations of Molecules.

JTHERGAS is a versatile calculator (implemented in JAVA) to estimate thermodynamic information from two dimensional graphical representations of molecules and radicals involving covalent bonds based on the Benson additivity method. The versatility of JTHERGAS stems from its inherent philosophy that all the fundamental data used in the calculation should be visible, to see exactly where the final values came from, and modifiable, to account for new data that can appear in the literature. The main use of this method is within automatic combustion mechanism generation systems where fast estimation of a large number and variety of chemical species is needed. The implementation strategy is based on meta-atom definitions and substructure analysis allowing a highly extensible database without modification of the core algorithms. Several interfaces for the database and the calculations are provided from terminal line commands, to graphical interfaces to web-services. The first order estimation of thermodynamics is based summing up the contributions of each heavy atom bonding description. Second order corrections due to steric hindrance and ring strain are made. Automatic estimate of contributions due to internal, external and optical symmetries are also made. The thermodynamical data for radicals is calculated by taking the difference due to the lost of a hydrogen radical taking into account changes in symmetry, spin, rotations, vibrations and steric hindrances. The software is public domain and is based on standard libraries such as CDK and CML.

Recognising haemorrhagic rash in children with fever: a survey of parents' knowledge.

BACKGROUND: Early recognition and treatment of meningococcal disease improves its outcome. Haemorrhagic rash is one of the most specific signs that parents can learn to recognise. OBJECTIVE: To determine the percentage of parents able to recognise a haemorrhagic rash and perform the tumbler test. METHODS: 123 parents of children consulting for mild injuries were interviewed about the significance and recognition of haemorrhagic rash in febrile children. RESULTS: Although 88% of parents undressed their children when they were febrile, it was never to look specifically for a skin rash. Only 7% (95% CI 3% to 12%) were able to recognise a petechial rash and knew the tumbler test. CONCLUSION: Information campaigns about the significance of haemorrhagic rash and about the tumbler test are needed.

[Noninvasive mechanical ventilation in paediatric intensive care units: which indications in 2010?]. / Ventilation non invasive en réanimation pédiatrique : quelles indications en 2010 ?

Noninvasive ventilation (NVI) is increasingly used in paediatrics, although there is a high variety of practices and a paucity of published data in paediatrics. The last French consensus conference recognized a specific role of NVI for infants suffering from acute bronchiolitis with apnoea, and acute respiratory failure due to laryngotracheomalacia and cystic fibrosis. NVI is feasible and can be beneficial in paediatric acute respiratory failure during neuromuscular diseases. Like in adults, its place in other diseases such as acute bronchoalveolitis without apnoea, acute respiratory failure during neuromuscular diseases, status asthmaticus, acute respiratory distress syndrome (ARDS) and postextubation respiratory failure is growing, even though not always defined. All these adult recommendations have not been validated in the pediatric setting, and, thus, taking the paediatric characteristics into account is essential. In 2010, NVI had an important place in PICU, and must be managed by a trained team whose practice is regularly evaluated.

[Weaning from invasive mechanical ventilation in pediatric patients (excluding premature neonates)]. / Le sevrage de la ventilation mécanique invasive en réanimation pédiatrique (à l'exclusion des prématurés).

The process of weaning from mechanical ventilation (WMV) is the same in children as in adults. In the pediatric literature, weaning failure rate ranges from 1.4 to 34%. So far, no indices of weaning success have been demonstrated to be sufficiently accurate. The criteria for assessing readiness to wean, which must be screened daily, have neither been validated nor adapted to the pediatric population. The spontaneous breathing test (SBT), the reference screening test for weaning, precedes extubation; it can be achieved with pressure support ventilation or spontaneous breathing (T piece or canopy or flow-inflating bag). A standardized weaning protocol (which can be computer driven) was used in only three pediatric studies and the impact on shortening the duration of mechanical ventilation has not yet been demonstrated. It should be paired with a sedative interruption protocol. Weaning criteria, SBT criteria, and/or protocol tolerance are guides, but clinicians must individualize decisions to use these criteria. The use of noninvasive ventilation is increasing and its place in weaning protocols for children needs to be determined; it might modify the definitions of weaning failure and weaning success in the future.

[Use of midazolam for refractory status epilepticus in children]. / Utilisation du midazolam dans l'état de mal épileptique réfractaire de l'enfant.

UNLABELLED: Morbidity and mortality are high in children with refractory status epilepticus (RSE). Here, we assess the efficacy of midazolam for RSE in children. METHODS: This was a retrospective analysis of 29 children admitted to the Lille University Hospital pediatric intensive care unit (PICU) for RSE between May 2006 and July 2008. The onset of the study corresponded with a new therapeutic protocol applied in the PICU for RSE where midazolam was proposed as the first-line treatment (bolus ten continuous infusion until control) to be replaced by thiopenthal in case of failure. RESULTS: We recorded 29 patients with RSE during the study period: 26 were treated with midazolam, including two where midazolam replaced thiopenthal because of hypotension. Midazolam successfully controlled RSE in 58% of patients. Mean delay to cessation of RSE was 48+/-65 minutes. Hypotension was observed in 8% of midazolam-treated patients and 71% of thiopenthal-treated patients. Overall mortality was 15% (4/26). Two deaths occurred long after the cessation of RSE. None of the deaths occurred in midazolam-treated patients. CONCLUSION: Midazolam is an efficient treatment for RSE in children. Morbidity and mortality appear to be lower with midazolam compared with other antiepileptic drugs used for the treatment of RSE.

Molecular method for the diagnosis of imported pediatric malaria.

Malaria is a polymorphous disease; it can be life threatening especially for children. We report a case of imported malaria in a boy, illustrating the epidemiological and clinical aspects of severe pediatric malaria. In this case real-time PCR was used to quantify Plasmodium falciparum DNA levels, to monitor the evolution under treatment, and to determine genetic mutations involved in chloroquine resistance. The major epidemiological features of imported malaria, and the difficulty to diagnose childhood severe malaria are described. The contribution of molecular methods for the diagnosis of imported malaria is discussed.

[Why teams in charge of children after a pediatric intensive care unit stay do not take into account the treatment limitation decisions previously made by intensivists]. / Pourquoi les décisions de limitation des traitements en réanimation ne sont-elles pas partagées avec les professionnels assurant les soins de l'enfant avant et après la réanimation?

UNLABELLED: The fact that some children may survive despite a limitation of treatment decision (LTD) made in the pediatric intensive care unit (PICU) is a recent concern. A previous study pointed out that the teams in charge of children after the PICU stay did not take previous PICU LTDs into account. PURPOSE: To identify the problems different units experience in cooperating with the PICU team, in order to increase the continuity of care for these children. STUDY DESIGN: Qualitative single-center study, using semi-structured interviews with physicians in charge of children who were discharged from the PICU even though a LTD was made. RESULTS: Nine pediatric subspecialists (hemato-oncologists, neurologists, and neurosurgeons) were interviewed, producing a corpus of approximately 80 pages of typed text. Three conflictual situations were identified by these physicians. The most frequently reported situation was being asked by the PICU team to give expert advice on a patient's prognosis, before a LTD was made. The 2 others had to defend a true care plan for children who were transferred to the PICU and designing a new care plan for children who were discharged from the PICU after a LTD was made. CONCLUSION: The medical reasoning model that is used for LTDs in the PICU generates conflictual situations when compared to the models that are used in other specialties. These models represent various expressions of subjectivity, as in any medical decision. Acknowledging this fact could facilitate its integration into clinical practice and should improve authentic debates that are necessary to ensure continuity of care for these children.

[Syncope and pre-syncope in children and adolescents: a prospective study in a pediatric emergency care unit]. / Syncopes et lipothymies chez l'enfant et l'adolescent : étude prospective dans une unité d'urgence pédiatrique.

OBJECTIVES: To assess in a pediatric emergency care unit (PECU): 1. The frequency of syncope and pre-syncope, 2. The incidence of diagnoses, 3. The value of investigations and cardiology and neurology consultations. METHODS: The data of PECU patients aged 2 years to 15 years and 3 months were prospectively collected over 1 year. Standard electrocardiogram and serum glucose were compulsory investigations. Schellong's orthostatic test was performed whenever possible. RESULTS: One hundred and fity-nine children (mean age, 11+/-4 years) were included, accounting for 0.8% of the PECU's visits: 48% had syncope, 52% had pre-syncope. The most common cause was neurally mediated syncope - 98 patients (62%), with vasovagal syncope for 80 patients - followed by neurological causes: 29 patients (18%). Neither cardiac arrhythmia nor obstructive cardiomyopathy was diagnosed. There were discrepancies between cardiologists' and pediatricians' ECG interpretations in 9% of cases. Diagnoses differed between cardiologists and pediatricians in 54% of 41 consultations. Diagnoses differed between neurologists and pediatricians in 54% of 42 consultations. No investigation except Schellong's orthostatic test led to modification of a previous diagnosis. CONCLUSION: This study emphasizes that the routine workup of pediatric syncope should focus on the patient's history and physical examination. Diagnostic testing should be minimal: ECG and Schellong's orthostatic test. The leading cause was neurocardiogenic syncope.