Resonant X-ray photoelectron spectroscopy: identification of atomic contributions to valence states.

Valence electronic structure is crucial for understanding and predicting reactivity. Valence non-resonant X-ray photoelectron spectroscopy (NRXPS) provides a direct method for probing the overall valence electronic structure. However, it is often difficult to separate the varying contributions to NRXPS; for example, contributions of solutes in solvents or functional groups in complex molecules. In this work we show that valence resonant X-ray photoelectron spectroscopy (RXPS) is a vital tool for obtaining atomic contributions to valence states. We combine RXPS with NRXPS and density functional theory calculations to demonstrate the validity of using RXPS to identify atomic contributions for a range of solutes (both neutral and ionic) and solvents (both molecular solvents and ionic liquids). Furthermore, the one-electron picture of RXPS holds for all of the closed shell molecules/ions studied, although the situation for an open-shell metal complex is more complicated. The factors needed to obtain a strong RXPS signal are investigated in order to predict the types of systems RXPS will work best for; a balance of element electronegativity and bonding type is found to be important. Additionally, the dependence of RXPS spectra on both varying solvation environment and varying local-covalent bonding is probed. We find that RXPS is a promising fingerprint method for identifying species in solution, due to the spectral shape having a strong dependence on local-covalency but a weak dependence on the solvation environment.

The outcome of patients in traumatic cardiac arrest presenting to deployed military medical treatment facilities: data from the UK Joint Theatre Trauma Registry.

BACKGROUND: The UK military was continuously engaged in armed conflict in Iraq and Afghanistan between 2003 and 2014, resulting in 629 UK fatalities. Traumatic cardiac arrest (TCA) is a precursor to traumatic death, but data on military outcomes are limited. In order to better inform military treatment protocols, the aim of this study was to define the epidemiology of TCA in the military population with a particular focus on survival rates and injury patterns. METHODS: A retrospective database analysis of the UK Joint Theatre Trauma Registry was undertaken. Patients who were transported to a UK deployed hospital between 2003 and 2014 and suffered TCA were included. Those patients injured by asphyxiation, electrocution, burns without other significant trauma and drowning were excluded. Data included mechanism of injury, Injury Severity Score (ISS), Abbreviated Injury Scale (AIS) for each body region and survival to deployed (Role 3) field hospital discharge. RESULTS: 424 TCA patients were identified during the study period; median age was 23 years, with a median ISS of 45. The most common mechanism of injury was explosive (55.7%), followed by gunshot wound (38.9%), road traffic collision (3.5%), crush (1.7%) and fall (0.2%). 45 patients (10.6% (95% CI 8.0% to 13.9%)) survived to deployed (Role 3) hospital discharge. The most prevalent body region with a severe to maximum AIS injury was the head, followed by the lower limbs, thorax and abdomen. Haemorrhage secondary to abdominal and lower limb injury was associated with survival; traumatic brain injury was associated with death. CONCLUSIONS: This study has shown that short-term survival from TCA in a military population is 10.6%. With appropriate and aggressive early management, although unlikely, survival is still potentially possible in military patients who suffer traumatic cardiac arrest.

The impact of ionic liquids on the coordination of anions with solvatochromic copper complexes.

Solvatochromic transition metal (TM)-complexes with weakly associating counter-anions are often used to evaluate traditional neutral solvent and anion coordination ability. However, when employed in ionic liquids (IL) many of the common assumptions made are no longer reliable. This study investigates the coordinating ability of weakly coordinating IL anions in traditional solvents and within IL solvents employing a range of solvatochromic copper complexes. Complexes of the form [Cu(acac)(tmen)][X] (acac = acetylacetonate, tmen = tetramethylethylenediamine) where [X]- = [ClO4]-, Cl-, [NO3]-, [SCN]-, [OTf]-, [NTf2]- and [PF6]- have been synthesised and characterised both experimentally and computationally. ILs based on these anions and imidazolium and pyrrolidinium cations, some of which are functionalised with hydroxyl and nitrile groups, have been examined. IL-anion coordination has been investigated and compared to typical weakly coordinating anions. We have found there is potential for competition at the Cu-centre and cases of anions traditionally assigned as weakly associating that demonstrate a stronger than expected level of coordinating ability within ILs. [Cu(acac)(tmen)][PF6] is shown to contain the least coordinating anion and is established as the most sensitive probe studied here. Using this probe, the donor numbers (DNs) of ILs have been determined. Relative donor ability is further confirmed based on the UV-Vis of a neutral complex, [Cu(sacsac)2] (sacsac = dithioacetylacetone), and DNs evaluated via23Na NMR spectroscopy. We demonstrate that ILs can span a wide donor range, similar in breadth to conventional solvents.

Solubility of alkali metal halides in the ionic liquid [C4C1im][OTf].

The solubilities of the metal halides LiF, LiCl, LiBr, LiI, NaF, NaCl, NaBr, NaI, KF, KCl, KBr, KI, RbCl, CsCl, CsI, were measured at temperatures ranging from 298.15 to 378.15 K in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([C4C1im][OTf]). Li(+), Na(+) and K(+) salts with anions matching the ionic liquid have also been investigated to determine how well these cations dissolve in [C4C1im][OTf]. This study compares the influence of metal cation and halide anion on the solubility of salts within this ionic liquid. The highest solubility found was for iodide salts, and the lowest solubility for the three fluoride salts. There is no outstanding difference in the solubility of salts with matching anions in comparison to halide salts. The experimental data were correlated employing several phase equilibria models, including ideal mixtures, van't Hoff, the λh (Buchowski) equation, the modified Apelblat equation, and the non-random two-liquid model (NRTL). It was found that the van't Hoff model gave the best correlation results. On the basis of the experimental data the thermodynamic dissolution parameters (ΔH, ΔS, and ΔG) were determined for the studied systems together with computed gas phase metathesis parameters. Dissolution depends on the energy difference between enthalpies of fusion and dissolution of the solute salt. This demonstrates that overcoming the lattice energy of the solid matrix is the key to the solubility of inorganic salts in ionic liquids.

Challenging the dogma of traumatic cardiac arrest management: a military perspective.

Attempts to resuscitate patients in traumatic cardiac arrest (TCA) have, in the past, been viewed as futile. However, reported outcomes from TCA in the past five years, particularly from military series, are improving. The pathophysiology of TCA is different to medical causes of cardiac arrest, and therefore, treatment priorities may also need to be different. This article reviews recent literature describing the pathophysiology of TCA and describes how the military has challenged the assumption that outcome is universally poor in these patients.

New experimental density data and soft-SAFT models of alkylimidazolium ([C(n)C1im]⁺) chloride (Cl⁻), methylsulfate ([MeSO4]⁻), and dimethylphosphate ([Me2PO4]⁻) based ionic liquids.

Ionic liquids have been shown to have application in several areas of importance in the context of sustainable industrial activity. One application of particular interest is the ability of certain ionic liquids to dissolve biomass. This clearly marks them as useful materials with application within biorefineries. In this contribution, we present new coarse-grained soft-SAFT models and experimental density data of chloride (Cl(-)), methylsulfate ([MeSO4](-)), and dimethylphosphate ([Me2PO4](-)) based ionic liquids which are relevant for biomass deconstruction processes. Model parameters were obtained by fitting to pure component temperature density data, and the models were subsequently tested by assessing their ability to accurately calculate viscosity and interfacial surface tension. We also developed models of mixtures of the ionic liquids with water and short-chain linear alcohols. We decomposed the contributions to the excess Gibbs energy of mixing to chemical and structural contributions, and used this to provide some insight into the driving forces for solubility of molecular species in these ionic liquids.

Hydrogen abstraction from n-butanol by the methyl radical: high level ab initio study of abstraction pathways and the importance of low energy rotational conformers.

Hydrogen abstraction reactions by the methyl radical from n-butanol have been investigated at the ROCBS-QB3 level of theory. Reaction energies and product geometries for the most stable conformer of n-butanol (ROH) have been computed, the reaction energies order α < γ < ß < δ < OH. The preference for n-butane to favour H-abstraction at C(ß) and C(γ) while, in contrast, n-butanol favours radical reactions at the C(α) carbon is rationalised. Transition state (TS) barriers and geometries for the most stable conformer of n-butanol are presented, and discussed with respect to the Hammond postulate. The reaction barriers order as α < OH < γ < ß < δ. This relative ordering is not consistent with product radical stability, C-H bond dissociation energies or previous studies using O[combining dot above]H and HO[combining dot above](2) radicals. We provide a molecular orbital based rationalisation for this ordering and answer two related questions: Why is the γ-channel more stable than the ß-channel? Why do the two C(γ)-H H-abstraction TS differ in energy? The method and basis set dependence of the TS barriers is investigated. The Boltzmann probability distribution for the n-butanol conformers suggests that low energy conformers are present in approximately equal proportions to the most stable conformer at combustion temperatures where CH(3) radicals are present. Thus, the relative significance of the various H-abstraction channels has been assessed for a selection of higher energy conformers (ROH'). Key results include finding that higher energy n-butanol conformers (E(ROH') > E(ROH)) can generate lower energy product radicals, E(ROH') < E(ROH). Moreover, higher energy conformers can also have a globally competitive TS energy for H-abstraction.

Understanding the polarity of ionic liquids.

The polarities of a wide range of ionic liquids have been determined using the Kamlet-Taft empirical polarity scales α, ß and π*, with the dye set Reichardt's Dye, N,N-diethyl-4-nitroaniline and 4-nitroaniline. These have been compared to measurements of these parameters with different dye sets and to different polarity scales. The results emphasise the importance of recognising the role that the nature of the solute plays in determining these scales. It is particularly noted that polarity scales based upon charged solutes can give very different values for the polarity of ionic liquids compared to those based upon neutral probes. Finally, the effects of commonplace impurities in ionic liquids are reported.

A common intracellular allosteric binding site for antagonists of the CXCR2 receptor.

BACKGROUND AND PURPOSE: We have previously shown that SB265610 (1-(2-bromo-phenyl)-3-(7-cyano-3H-benzotriazol-4-yl)-urea) behaves as an allosteric, inverse agonist at the C-X-C chemokine (CXCR)2 receptor. The aim of this study was to determine whether SB265610, in addition to two other known antagonists, bind to either of the two putative, topographically distinct, allosteric binding sites previously reported in the Literature. EXPERIMENTAL APPROACH: Ten single point mutations were introduced into the CXCR2 receptor using site-directed mutagenesis. Three CXCR2 antagonists were investigated, SB265610, Pteridone-1 (2-(2,3 difluoro-benzylsulphanyl)-4-((R)-2-hydroxy-1-methyl-ethylamino)-8H-pteridin-7-one) and Sch527123 (2-hydroxy-N,N-dimethyl-3-{2-[[(R)-1-(5-methyl-furan-2-yl)-propyl]amino]-3,4-dioxo-cyclobut-1enylamino}-benzamide), and the effect of these mutations on their binding affinity and ability to inhibit interleukin-8-stimulated binding of [(35)S]GTPgammaS was examined. KEY RESULTS: Seven of the nine mutations introduced into the C-terminal domain and intracellular loops of the receptor produced a significant reduction in affinity at least one of the antagonists tested. Of those seven mutations, three produced a significant reduction in the affinity of all three antagonists, namely K320A, Y314A and D84N. In all but one mutation, the changes observed on antagonist affinity were matched with effects on inhibition of interleukin-8-stimulated [(35)S]GTPgammaS binding. CONCLUSIONS AND IMPLICATIONS: These antagonists bind to a common intracellular, allosteric, binding site of the CXCR2 receptor, which has been further delineated. As many of these mutations are close to the site of G protein coupling or to a region of the receptor that is responsible for the transduction of the activation signal, our results suggest a molecular mechanism for the inhibition of receptor activation.

Self assessment exercises in Intensive Care Medicine.

Intensive Care Medicine (ICM) is no longer the exclusive preserve of anaesthetists as both emergency medicine and general medicine trainees now also train in this increasingly important speciality. This edition of the JRAMC self assessment question series serves to cover some of the current 'hot topics' in ICM and enables readers with experience of ICM to test their knowledge as well as educating junior trainees in relevant subjects that they may be unfamiliar with. Similarly, the Focus On .... series of papers elsewhere in this journal demonstrate the increasing importance of ICM in the deployed Field Hospital setting.

Why are ionic liquid ions mainly associated in water? A Car-Parrinello study of 1-ethyl-3-methyl-imidazolium chloride water mixture.

In this study we present the results of a first principles molecular dynamics simulation of a single 1-ethyl-3-methyl-imidazolium chloride [C(2)C(1)im][Cl] ion pair dissolved in 60 water molecules. We observe a preference of the in plane chloride coordination with respect to the cation ring plane as compared to the energetic slightly more demanding on top coordination. Evaluation of the different radial distribution functions demonstrates that the structure of the hydration shell around the ion pair differs significantly from bulk water and that no true ion pair dissociation in terms of completely autonomous solvation shells takes place on the timescale of the simulation. In addition, dipole moment distributions of the solvent in distinct solvation shells around different functional parts of the [C(2)C(1)im][Cl] ion pair are calculated from maximally localized Wannier functions. The analysis of these distributions gives evidence for a depolarization of water molecules close to the hydrophobic parts of the cation as well as close to the anion. Examination of the angular distribution of different OH(H(2)O)-X angles in turn shows a linear coordination of chloride accompanied by a tangential orientation of water molecules around the hydrophobic groups, being a typical feature of hydrophobic hydration. Based on these orientational aspects, a structural model for the obvious preference of ion pair association is developed, which justifies the associating behavior of solvated [C(2)C(1)im][Cl] ions in terms of an energetically favorable interface between the solvation shells of the anion and the hydrophobic parts of the cation.

Meiosis in mammals: recombination, non-disjunction and the environment.

By comparison with other species, the meiotic process in the human female is extraordinarily error-prone. In addition to the well-known effect of advancing maternal age, recent studies have demonstrated that the number and location of meiotic recombination events influences the likelihood of meiotic non-disjunction in our species. Although this association extends to many other organisms, the factors that influence the number and placement of exchanges within a cell remain poorly understood. Like other aspects of meiosis, the control of recombination is likely to be subject to variation among species. In this review we summarize data from recent studies in mammals; the combined data suggest that both genetic and environmental factors influence recombination in mammals and, importantly, that control mechanisms probably differ between males and females.

Emergency thoracotomy in thoracic trauma-a review.

Thoracic trauma is one of the leading causes of death in all age groups and accounts for 25-50% of all traumatic injuries. While the majority of patients with thoracic trauma can be managed conservatively, a small but significant number requires emergency thoracotomy as part of their initial resuscitation. The procedure has been advocated for evacuation of pericardial tamponade, direct control of intrathoracic haemorrhage, control of massive air-embolism, open cardiac massage and cross-clamping of the descending aorta. Emergency thoracotomy can be defined as thoracotomy "occurring either immediately at the site of injury, or in the emergency department or operating room as an integral part of the initial resuscitation process". Following emergency thoracotomy, the overall survival rates for penetrating thoracic trauma are around 9-12% but have been reported to be as high as 38%. The survival rate for blunt trauma is approximately 1-2%. The decision to perform emergency thoracotomy involves careful evaluation of the scientific, ethical, social and economic issues. This article aims to provide a review of the current literature and to outline the pathophysiological features, technical manoeuvres and selective indications for emergency thoracotomy as a component of the initial resuscitation of trauma victims with thoracic injury.