Librarianship in the Twenty-First Century

Battin urges academic libraries to imagine the future from a twenty-first century perspective. To flourish in a digital society, libraries must transform themselves, intentionally and continuously, through managing information resources, redefining roles of information professionals, and nourishing future leaders

A comprehensive experimental and modeling study of isobutene oxidation

Isobutene is an important intermediate in the pyrolysis and oxidation of higher-order branched alkanes, and it is also a component of commercial gasolines. To better understand its combustion characteristics, a series of ignition delay time (IDT) and laminar flame speed (LFS) measurements have been performed. In addition, flow reactor speciation data recorded for the pyrolysis and oxidation of isobutene is also reported. Predictions of an updated kinetic model described herein are compared with each of these data sets, as well as with existing jet-stirred reactor (JSR) species measurements.IDTs of isobutene oxidation were measured in four different shock tubes and in two rapid compression machines (RCMs) under conditions of relevance to practical combustors. The combination of shock tube and RCM data greatly expands the range of available validation data for isobutene oxidation models to pressures of 50 atm and temperatures in the range 666-1715 K. Isobutene flame speeds were measured experimentally at 1 atm and at unburned gas temperatures of 298-398 K over a wide range of equivalence ratios. For the flame speed results, there was good agreement between different facilities and the current model in the fuel-rich region. Ab initio chemical kinetics calculations were carried out to calculate rate constants for important reactions such as H-atom abstraction by hydroxyl and hydroperoxyl radicals and the decomposition of 2-methylallyl radicals.A comprehensive chemical kinetic mechanism has been developed to describe the combustion of isobutene and is validated by comparison to the presently considered experimental measurements. Important reactions, highlighted via flux and sensitivity analyses, include: (a) hydrogen atom abstraction from isobutene by hydroxyl and hydroperoxyl radicals, and molecular oxygen; (b) radical-radical recombination reactions, including 2-methylallyl radical self-recombination, the recombination of 2-methylallyl radicals with hydroperoxyl radicals; and the recombination of 2-methylallyl radicals with methyl radicals; (c) addition reactions, including hydrogen atom and hydroxyl radical addition to isobutene; and (d) 2-methylallyl radical decomposition reactions. The current mechanism accurately predicts the IDT and LFS measurements presented in this study, as well as the JSR and flow reactor speciation data already available in the literature.The differences in low-temperature chemistry between alkanes and alkenes are also highlighted. in this work. In normal alkanes, the fuel radical (R) over dot adds to molecular oxygen forming alkylperoxyl (R(O) over dot(2)) radicals followed by isomerization and chain branching reactions which promote low-temperature fuel reactivity. However, in alkenes, because of the relatively shallow well (similar to 20 kcal mol(-1)) for R(O) over dot(2) formation compared to similar to 35 kcal mol(-1) in alkanes, the (R) over dot+O-2 (sic) R(O) over dot(2) equilibrium lies more to the left favoring (R) over dot+O-2 rather than R(O) over dot(2) radical stabilization. Based on this work, and related studies of allylic systems, it is apparent that reactivity for alkene components at very low temperatures (1300 K), the reactivity is mainly governed by the competition between hydrogen abstractions by molecular oxygen and OH radicals. (C) 2016 The Combustion Institute. Published by Elsevier Inc. All rights reserved.The work at NUI Galway was supported by Saudi Aramco under the FUELCOM program. Collaboration between NUI Galway and LRGP enters in the frame the COST Action CM1404.peer-reviewed2017-03-1

An experimental and modeling study of propene oxidation. Part 2: Ignition delay time and flame speed measurements

Journal articleExperimental data obtained in this study (Part II) complement the speciation data presented in Part I, but also offer a basis for extensive facility cross-comparisons for both experimental ignition delay time (IDT) and laminar flame speed (LFS) observables.To improve our understanding of the ignition characteristics of propene, a series of IDT experiments were performed in six different shock tubes and two rapid compression machines (RCMs) under conditions not previously studied. This work is the first of its kind to directly compare ignition in several different shock tubes over a wide range of conditions. For common nominal reaction conditions among these facilities, cross-comparison of shock tube IDTs suggests 20-30% reproducibility (2 sigma) for the IDT observable. The combination of shock tube and RCM data greatly expands the data available for validation of propene oxidation models to higher pressures (2-40 atm) and lower temperatures (750-1750 K).Propene flames were studied at pressures from 1 to 20 atm and unburned gas temperatures of 295-398 K for a range of equivalence ratios and dilutions in different facilities. The present propene-air LFS results at 1 atm were also compared to LFS measurements from the literature. With respect to initial reaction conditions, the present experimental LFS cross-comparison is not as comprehensive as the IDT comparison; however, it still suggests reproducibility limits for the LFS observable. For the LFS results, there was agreement between certain data sets and for certain equivalence ratios (mostly in the lean region), but the remaining discrepancies highlight the need to reduce uncertainties in laminar flame speed experiments amongst different groups and different methods. Moreover, this is the first study to investigate the burning rate characteristics of propene at elevated pressures (>5 atm).IDT and LFS measurements are compared to predictions of the chemical kinetic mechanism presented in Part I and good agreement is observed. (C) 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.The Rensselaer group was supported by the U.S. Air Force Office of Scientific Research (Grant No. FA9550-11-1-0261) with Dr. Chiping Li as technical monitor. Work at the University of Connecticut and at Princeton University was supported as part of the Combustion Energy Frontier Research Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Science, under Award Number DE-SC0001198. The work at Stanford University was supported by the Air Force Office of Scientific Research through AFOSR Grant No. FA9550-11-1-0217, under the AFRL Integrated Product Team, with Dr. Chiping Li as contract monitor. The work at NUI Galway was kindly supported by Saudi Aramco. The work of KAUST authors was supported by Saudi Aramco under the FUELCOM program.peer-reviewe

Saturated very long-chain fatty acids regulate macrophage plasticity and invasiveness

Saturated very long-chain fatty acids (VLCFA, ≥ C22), enriched in brain myelin and innate immune cells, accumulate in X-linked adrenoleukodystrophy (X-ALD) due to inherited dysfunction of the peroxisomal VLCFA transporter ABCD1. In its severest form, X-ALD causes cerebral myelin destruction with infiltration of pro-inflammatory skewed monocytes/macrophages. How VLCFA levels relate to macrophage activation is unclear. Here, whole transcriptome sequencing of X-ALD macrophages indicated that VLCFAs prime human macrophage membranes for inflammation and increased expression of factors involved in chemotaxis and invasion. When added externally to mimic lipid release in demyelinating X-ALD lesions, VLCFAs did not activate toll-like receptors in primary macrophages. In contrast, VLCFAs provoked pro-inflammatory responses through scavenger receptor CD36-mediated uptake, cumulating in JNK signalling and expression of matrix-degrading enzymes and chemokine release. Following pro-inflammatory LPS activation, VLCFA levels increased also in healthy macrophages. With the onset of the resolution, VLCFAs were rapidly cleared in control macrophages by increased peroxisomal VLCFA degradation through liver-X-receptor mediated upregulation of ABCD1. ABCD1 deficiency impaired VLCFA homeostasis and prolonged pro-inflammatory gene expression upon LPS treatment. Our study uncovers a pivotal role for ABCD1, a protein linked to neuroinflammation, and associated peroxisomal VLCFA degradation in regulating macrophage plasticity

Spatial stability of Avena sterilis ssp. ludoviciana populations under annual applications of low rates of imazamethabenz

9 páginas, ilustraciones y tablas estadísticas.Long-term experiments were conducted in two winter barley fields in central Spain to determine the spatial stability of Avena sterilis ssp. ludoviciana populations under annual applications of low rates of imazamethabenz herbicide. Weed density was sampled every year (over 5 years in the first field and over 3years in the second) on the same grid locations prior to herbicide application. Although weed patches were stable in their location, weed density decreased in most of the years. In the first field, the populations decreased exponentially over the 5-year period. The rates of population decline were dependent on the initial density of the population, being higher for the central core of the patches and lower for the low-density areas. Under the conditions present in this experiment, it was possible to reduce heavy weed patches (up to 1200 seedlings m)2) down to relatively safe levels (18 seedlings m)2) in a period of 3years using a density-specific control programme, applying low rates of herbicides when weed densities were below a given level (1000 seedlings m)2). However, under adverse environmental conditions, half rates of the herbicide failed to control the weed populations adequately. The stability of the location of patches of A.sterilis ssp. ludoviciana suggest that weed seedling distributions mapped in one year are good predictors of future seedling distributions. However, the actual densities established each year will depend on the control level achieved the previous year and the climatic conditions present during the establishment period.(project AGF99-1125), by the Consejerıa de Educacion of the Community of Madrid and by the European Social Programme.Peer reviewe