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Efficient and inexpensive catalysts for the O2 reduction reaction (ORR) are needed for the advancement of renewable energy technologies. In this study, we designed a computational catalyst‐screening method to identify single and di‐atom metal dopants from first‐row transition elements supported on defect‐containing nitrogenated graphene surfaces for the ORR. Based on formation‐energy calculations and micro‐kinetic modelling of reaction pathways using intermediate binding free energies, we have identified four potentially interesting single‐atom catalysts (SACs) and fifteen di‐atom catalysts (DACs) with relatively high estimated catalytic activity at 0.8 V vs RHE. Among the best SACs, MnNC shows high stability in both acidic and alkaline media according to our model. For the DACs, we found four possible candidates, MnMn, FeFe, CoCo, and MnNi doped on quad‐atom vacancy sites having considerable stability over a wide pH range. The remaining SACs and DACs with high activity are either less stable or show a stability region at an alkaline pH. [ABSTRACT FROM AUTHOR]

Efficient and inexpensive catalysts for the O2 reduction reaction (ORR) are needed for the advancement of renewable energy technologies. In this study, we designed a computational catalyst‐screening method to identify single and di‐atom metal dopants from first‐row transition elements supported on defect‐containing nitrogenated graphene surfaces for the ORR. Based on formation‐energy calculations and micro‐kinetic modelling of reaction pathways using intermediate binding free energies, we have identified four potentially interesting single‐atom catalysts (SACs) and fifteen di‐atom catalysts (DACs) with relatively high estimated catalytic activity at 0.8 V vs RHE. Among the best SACs, MnNC shows high stability in both acidic and alkaline media according to our model. For the DACs, we found four possible candidates, MnMn, FeFe, CoCo, and MnNi doped on quad‐atom vacancy sites having considerable stability over a wide pH range. The remaining SACs and DACs with high activity are either less stable or show a stability region at an alkaline pH. [ABSTRACT FROM AUTHOR]

Background: We aimed to determine the development in the use of video laryngoscopy over a 9‐year period, and its possible impact on airway planning and management. Methods: We retrieved 822,259 records of tracheal intubations recorded from 2008 to 2016 in the Danish Anaesthesia Database. The circumstances regarding pre‐operative airway assessment, the scheduled airway management plan and the actual airway management concerning video laryngoscopy were reported for each year of observation. Further, the association between year of observation and various airway management related outcomes was evaluated by multivariate logistic regression. Results: There was a significant increase in airway management with 'advanced technique successfully used within two attempts' from 2.7% in 2008 to 15.5% in 2016 (p <.0001). This predominantly reflects use of video laryngoscopy. The prevalence of tracheal intubations 'scheduled for video laryngoscopy' increased from 3.5% in 2008 to 10.6% in 2016 (p <.0001). We found a significant increase in the prevalence of anticipated difficulties with intubations by direct laryngoscopy from 1.8% in 2008 to 5.2% in 2016 (p <.0001). The prevalence of failed tracheal intubations decreased from 0.14% in 2008 to 0.05% in 2016 (p <.0001). Conclusion: From 2008 to 2016, a period of massive implementation of video laryngoscopes, a significant change in airway management behaviour was recorded. Increasingly, video laryngoscopy is becoming a first‐choice device for both acute and routine airway management. Most importantly, the data showed a noticeable reduction in failed intubation over the time of observation. [ABSTRACT FROM AUTHOR]

The establishment of a molecular view of heterogeneous catalysis has been hampered for a number of reasons. There are, however, recent developments, which show that we are now on the way towards reaching a molecular-scale picture of the way solids work as catalysts. By a combination of new theoretical methods, detailed experiments on model systems, and synthesis and in situ characterization of nano-structured catalysts, we are witnessing the first examples of complete atomic-scale insight into the structure and mechanism of surface-catalyzed reactions. This insight has already proven its value by enabling a rational design of new catalysts. We illustrate this important development in heterogeneous catalysis by highlighting recent examples of catalyst systems for which it has been possible to achieve such a detailed understanding. In particular, we emphasize examples where this progress has made it possible to propose entirely new catalysts, which have then been proven experimentally to exhibit improved performance in terms of catalytic activity or selectivity. [ABSTRACT FROM AUTHOR]

The modification of the electronic and chemical properties of Pt(111) surfaces by subsurface 3d transition metals was studied using density-functional theory. In each case investigated, the Pt surface d-band was broadened and lowered in energy by interactions with the subsurface 3d metals, resulting in weaker dissociative adsorption energies of hydrogen and oxygen on these surfaces. The magnitude of the decrease in adsorption energy was largest for the early 3d transition metals and smallest for the late 3d transition metals. In some cases, dissociative adsorption was calculated to be endothermic. The surfaces investigated in this study had no lateral strain in them, demonstrating that strain is not a necessary factor in the modification of bimetallic surface properties. The implications of these findings are discussed in the context of catalyst design, particularly for fuel cell electrocatalysts. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Self-consistent density functional calculations of the hydroxylated (0001) corundum surfaces are presented. It is demonstrated that the hydroxylated surfaces are the most stable under most, but not all, conditions. Hydroxylation significantly lowers the surface free energy of α-alumina. The stability of the hydrated surface resolves the discrepancies between the morphology of the α-alumina (0001) surface observed under ultra-high vacuum, and at ambient conditions. A method for the calculation of the equilibrium surface stoichiometry is proposed. The proposed approach provides a valuable connection between theoretical calculations and experiments with metal oxides. [ABSTRACT FROM AUTHOR]

We report density functional theory calculations of the interaction of Cu and Pd with the (0001) surface of α-Al[sub 2]O[sub 3]. The interaction of those metals with the oxide surface varies from covalent-like for the aluminum rich surface to ionic-like for the oxygen terminated surface. Stoichiometric hydroxylation of the surface does not increase the metal-oxide interaction significantly. We suggest that defects created upon hydroxylation are the main mechanism to explain the observed metal wetting of the oxide. © 2001 American Institute of Physics. [DOI: 10.1063/1.1421107]. [ABSTRACT FROM AUTHOR]

In this article, the author reflects on the article published within the issue on efficacy of the numerous supraglottic airway devices (SAD) for paediatric anaesthesia and benefits of meta-analysis. It mentions guidance of the National Institute for Health and Care Excellence (NICE) Decision Support Unit in carrying out their analysis and associated consistency checks and sensitivity analyses. It also mentions health technology assessments and drug re-imbursement decisions.

• Optimal H 2 partial pressure increases TOF due to shifting equilibria at steady state. • C 2 H 4 desorption is not a rate or selectivity limiting step at low conversion. • Destabilizing CH 3 CH∗ is a design principle for selectivity over (1 1 1) facets. • Better selectivity from less reactive electronic structure and geometric effects Catalytic dehydrogenation of light alkanes may offer more efficient routes to selectively producing light olefins, which are some of the most important chemical building blocks in the industry, in terms of scale. We present a descriptor based micro-kinetic model of the trends in selectivity and activity of non-oxidative dehydrogenation of ethane over close-packed metal facets and through varied reaction conditions. Our model predicts and explains the experimentally observed promotion effect on turnover rate from co-feeding hydrogen as an effect of the shifting equilibria in steady state. At low conversion reaction conditions over Pt, the path to ethene goes through ethane dehydrogenation to ethyl, CH 3 CH 2 ∗, then to ethene while the non-selective pathway to methane and deeply dehydrogenated species is predicted to go through dehydrogenation via CH 3 CH∗. This implies that the desorption step of ethene is not the limiting step for selectivity and that geometric effects that stabilize CH 2 CH 2 ∗ compared to CH 3 CH∗ are desirable properties of a better catalyst. Removing reactive bridge and 3-fold sites facilitates this, which may be achievable by sufficient concentrations of tin in platinum. The included model code furthermore provides a base for easy tuning and for expanding the study to other thermodynamic conditions, other facets, alloys or the reaction network to longer hydrocarbons or to oxidative pathways. [ABSTRACT FROM AUTHOR]

Indications for using supraglottic airway devices have widened over time and they now hold a prominent role in guidelines for difficult airway management. We aimed to describe the use of supraglottic airway devices in difficult airway management. We included adult patients undergoing general anaesthesia registered in the Danish Anaesthesia Database from 2008 to 2012 whose airway management had been recorded as difficult, defined as: ≥ 3 tracheal intubation attempts; failed tracheal intubation; or difficult facemask ventilation. In the Danish Anaesthesia Database, a separate difficult airway management module requires the technique used in each successive airway management attempt to be recorded. The primary aim of the study was to describe the use of supraglottic airway devices in cases of difficult airway management. Secondary aims were to examine success rates of supraglottic airway devices in difficult airway management cases, and specifically in the cases of 'cannot intubate, cannot facemask ventilate'. Difficult airway management occurred in 4898 (0.74% (95%CI 0.72-0.76%)) of 658,104 records of general anaesthesia. Supraglottic airway devices were used or use was attempted in 607 cases of difficult airway management (12.4% (95%CI 11.5-13.3%)), and were successful in 395 (65.1% (95%CI 61.2-68.8%)) cases. In 'cannot intubate, cannot facemask ventilate' situations, supraglottic airway devices were used in 86 (18.9% (95%CI 15.6-22.8%)) of 455 records and were successful in 54 (62.8% (95%CI 52.2-72.3%)) cases. We found that supraglottic airway devices are not widely used in the management of the difficult airway despite their prominent role in difficult airway management guidelines. [ABSTRACT FROM AUTHOR]

We compared implementation of systematic airway assessment with existing practice of airway assessment on prediction of difficult mask ventilation. Twenty-six departments were cluster-randomised to assess eleven risk factors for difficult airway management (intervention) or to continue with their existing airway assessment (control). In both groups, patients predicted as a difficult mask ventilation and/or difficult intubation were registered in the Danish Anaesthesia Database, with a notational summary of airway management. The trial's primary outcome was the respective incidence of unpredicted difficult and easy mask ventilation in the two groups. Among 94,006 patients undergoing mask ventilation, the incidence of unpredicted difficult mask ventilation in the intervention group was 0.91% and 0.88% in the control group; (OR) 0.98 (95% CI 0.66-1.44), p = 0.90. The incidence of patients predicted difficult to mask ventilate, but in fact found to be easy ('falsely predicted difficult') was 0.64% vs. 0.35% (intervention vs. control); OR 1.56 (1.01-2.42), p = 0.045. In the intervention group, 86.3% of all difficult mask ventilations were not predicted, compared with a higher proportion 91.2% in the control group, OR 0.61 (0.41-0.91), p = 0.016. The systematic intervention did not alter the overall incidence of unpredicted difficult mask ventilations, but of the patients who were found to be difficult to mask ventilate, the proportion predicted was higher in the intervention group than in the control group. However, this was at a 'cost' of increasing the number of mask ventilations falsely predicted to be difficult. [ABSTRACT FROM AUTHOR]

Background: The emergency surgical airway (ESA) is the final option in difficult airway management. We identified ESA procedures registered in the Danish Anaesthesia Database (DAD) and described the performed airway management.Methods: We extracted a cohort of 452 461 adult patients undergoing general anaesthesia and tracheal intubation from the DAD from June 1, 2008 to March 15, 2014. Difficult airway management involving an ESA was retrieved for analysis and compared with hospitals files. Two independent reviewers evaluated airway management according to the ASAs'2003 practice guideline for difficult airway management.Results: In the DAD cohort 27 out of 452 461 patients had an ESA representing an incidence of 0.06 events per thousand (95% CI; 0.04 to 0.08). A total of 12 149/452 461 patients underwent Ear-Nose and Throat (ENT) surgery, giving an ESA incidence among ENT patients of 1.6 events per thousand (95% CI; 1.0-2.4). A Supraglottic Airway Device and/or the administration of a neuromuscular blocking agent before ESA were used as a rescue in 6/27 and 13/27 of the patients, respectively. In 19/27 patients ENT surgeons performed the ESA's and anaesthetists attempted 6/27 of the ESAs of which three failed. Reviewers evaluated airway management as satisfactory in 10/27 patients.Conclusions: The incidence of ESA in the DAD cohort was 0.06 events per thousand. Among ENT patients, the ESA Incidence was 1.6 events per thousand. Airway management was evaluated as satisfactory for 10/27 of the patients. ESA performed by anaesthetists failed in half of the patients. [ABSTRACT FROM AUTHOR]

Background: Unanticipated difficult intubation remains a challenge in anaesthesia. The Simplified Airway Risk Index (SARI) is a multivariable risk model consisting of seven independent risk factors for difficult intubation. Our aim was to compare preoperative airway assessment based on the SARI with usual airway assessment.Methods: From 01.10.2012 to 31.12.2013, 28 departments were cluster-randomized to apply the SARI model or usual airway assessment. The SARI group implemented the SARI model. The Non-SARI group continued usual airway assessment, thus reflecting a group of anaesthetists' heterogeneous individual airway assessments. Preoperative prediction of difficult intubation and actual intubation difficulties were registered in the Danish Anaesthesia Database for both groups. Patients who were preoperatively scheduled for intubation by advanced techniques (e.g. video laryngoscopy; flexible optic scope) were excluded from the primary analysis. Primary outcomes were the proportions of unanticipated difficult and unanticipated easy intubation.Results: A total of 26 departments (15 SARI and 11 Non-SARI) and 64 273 participants were included. In the primary analyses 29 209 SARI and 30 305 Non-SARI participants were included.In SARI departments 2.4% (696) of the participants had an unanticipated difficult intubation vs 2.4% (723) in Non-SARI departments. Odds ratio (OR) adjusted for design variables was 1.03 (95% CI: 0.77-1.38). The proportion of unanticipated easy intubation was 1.42% (415) in SARI departments vs 1.00% (302) in Non-SARI departments. Adjusted OR was 1.26 (0.68-2.34).Conclusions: Using the SARI compared with usual airway assessment we detected no statistical significant changes in unanticipated difficult- or easy intubations.Clinical Trial Registration: NCT01718561. [ABSTRACT FROM AUTHOR]

The article talks about the search for the active site of a catalyst for a chemical reaction being an objective of research for almost a century. It talks about Taylor's concept that a solid catalyst will have all extremes between the case in which all the atoms in the surface are active and that in which relatively few are so active. The article also talks about the enhanced ammonia synthesis rate achieved by addition of alkali metals as promoters.

We present a systematic theoretical investigation of the surface properties, stability, and reactivity of rocksalt type alkaline-earth metal oxides including MgO, CaO, SrO, and BaO. The accuracy of commonly used exchange-correlation density functionals (LDA, PBE, RPBE, PBEsol, BEEF-vdW, and hybrid HSE) and random-phase approximation (RPA) is evaluated and compared to existing experimental values. Calculated surface energies of the four most stable surface facets under vacuum conditions, the (100) surface, the metal and oxygen terminated octopolar (111), and the (110) surfaces, exhibit a monotonic increase in stability from MgO to BaO. On the MgO(100) surface, adsorption of CO, NO, and CH4 is characterized by physisorption while H2O chemisorbs, which is in agreement with experimental findings. We further use the on-top metal adsorption of CO and NO molecules to map out the surface energetics of each alkaline-earth metal oxide surface. The considered functionals all qualitatively predict similar adsorption energy trends. The ordering between the adsorption energies on different surface facets can be attributed to differences in the local geometrical surface structure and the electronic structure of the metal constituent of the alkaline-earth metal oxide. The striking observation that CO adsorption strength is weaker than NO adsorption on the (100) terraces as the period of the alkaline-earth metal in the oxide increases is analyzed in detail in terms of charge redistribution within the σ and π channels of adsorbates. Finally, we also present oxygen adsorption and oxygen vacancy formation energies in these oxide systems. [ABSTRACT FROM AUTHOR]

Both the American Society of Anesthesiologists and the UK NAP4 project recommend that an unspecified pre-operative airway assessment be made. However, the choice of assessment is ultimately at the discretion of the individual anaesthesiologist. We retrieved a cohort of 188 064 cases from the Danish Anaesthesia Database, and investigated the diagnostic accuracy of the anaesthesiologists' predictions of difficult tracheal intubation and difficult mask ventilation. Of 3391 difficult intubations, 3154 (93%) were unanticipated. When difficult intubation was anticipated, 229 of 929 (25%) had an actual difficult intubation. Likewise, difficult mask ventilation was unanticipated in 808 of 857 (94%) cases, and when anticipated (218 cases), difficult mask ventilation actually occurred in 49 (22%) cases. We present a previously unpublished estimate of the accuracy of anaesthesiologists' prediction of airway management difficulties in daily routine practice. Prediction of airway difficulties remains a challenging task, and our results underline the importance of being constantly prepared for unexpected difficulties. [ABSTRACT FROM AUTHOR]

The formation and oxidation reaction energies of 16 transition metal oxides (TMOs) are benchmarked against experiments with an increasing complexity of the exchange-correlation (xc) functionals: PBE, PBE + U with a single U for each transition metal element, PBEO (25% exact exchange included), EXX (100% exact exchange), and EXX + RPA (random phase approximation for the correlation energy). Although rather challenging on standard CPU computing facilities, the RPA calculations were performed efficiently on graphic processing units (GPUs). For the formation energies, the PBE + U, PBEO, EXX + RPA improves significantly over PBE with mean absolute errors (MAE) of 0.83 (PBE), 0.39 (PBE + f/), 0.34 (PBEO), and 0.39 (EXX + RPA) eV per oxygen. In addition, EXX + RPA improves over the other xc functionals on the oxidation reaction energies, with MAE of 0.27 (PBE), 0.28 (PBE+ U), 0.30 (PBEO), to 0.13 (EXX + RPA) eV per oxygen. The distinct trend observed for the calculated oxidation reaction energies compared to the formation energies is due to that the errors in formation energies for PBE and EXX + RPA are systematic; while for PBE + U and PBEO the deviations have both signs, so that the error cancellations between different valence states work better for PBE and EXX + RPA. Finally, we compared the performance of the EXX + RPA for total energies and G0W0, which uses the random phase approximation in constructing the W kernel, for band gaps, and discuss a few challenges for the EXX + RPA method on TMOs. [ABSTRACT FROM AUTHOR]

CC coupling: The free energies of the CO and CN− reduction pathways are calculated to identify the routes favored by FeMoco and FeVco nitrogenase active sites. The potential‐limiting step in CO reduction is the initial protonation and adsorption of CHO*. CN− reduction is limited by a second protonation of HCN. Higher‐order hydrocarbons, limited by the same steps, are likely built from CH2* intermediates common to both CO and CN− reduction pathways. [ABSTRACT FROM AUTHOR]

Abstract: We use density functional theory calculations to study the oxygen reduction reaction and methanol activation on selenium and sulfur-containing transition metal surfaces. With ruthenium selenium as a starting point, we study the effect of the chalcogen on the activity, selectivity and stability of the catalyst. Ruthenium surfaces with moderate content of selenium are calculated active for the oxygen reduction reaction, and insensitive to methanol. A significant upper limit for the activity of transition metal chalcogenides is estimated. [Copyright &y& Elsevier]

Recent advances in the understanding of reactivity trends for chemistry at transition-metal surfaces have enabled in silico design of heterogeneous catalysts in a few cases. The current status of the field is discussed with an emphasis on the role of coupling theory and experiment and future challenges. [ABSTRACT FROM AUTHOR]

Over the past decade the theoretical description of surface reactions has undergone a radical development. Advances in density functional theory mean it is now possible to describe catalytic reactions at surfaces with the detail and accuracy required for computational results to compare favourably with experiments. Theoretical methods can be used to describe surface chemical reactions in detail and to understand variations in catalytic activity from one catalyst to another. Here, we review the first steps towards using computational methods to design new catalysts. Examples include screening for catalysts with increased activity and catalysts with improved selectivity. We discuss how, in the future, such methods may be used to engineer the electronic structure of the active surface by changing its composition and structure. [ABSTRACT FROM AUTHOR]

Abstract: A general scheme for the screening of heterogeneous catalysts using density functional theory (DFT) calculations is presented, and the scheme is illustrated with a search for catalysts for the hydrogen evolution reaction. Simple techniques to estimate the activity of binary surface and bulk alloys for this reaction are described, and several computational tests for stability in reaction environments are presented. Careful application of these activities and stability criteria to a database of DFT calculations on ∼750 binary transition metal alloys leads to the identification of several surface and bulk alloys that are predicted to perform comparably to platinum, the canonical hydrogen evolution catalyst. This study marks the first use of full DFT calculations for high-throughput screening of transition metal catalysts. [Copyright &y& Elsevier]

Step sites play an important role in many catalytic reactions. This paper reviews recent results on metal catalysts for syngas reactions with emphasis on steam reforming. Modern characterization techniques (STEM, HREM...) and theoretical calculations (DFT) has allowed a more quantitative explanation of the impact of step sites on catalyst activity and side reactions such as carbon formation. This leads to a discussion of principles for catalyst promotion. [ABSTRACT FROM AUTHOR]

Abstract: A simple scheme for the estimation of oxygen binding energies on transition metal surface alloys is presented. It is shown that a d-band center model of the alloy surfaces is a convenient and appropriate basis for this scheme; variations in chemical composition, strain effects, and ligand effects are all incorporated into the binding energy analysis through this parameter. With few exceptions, the agreement of the results from the simple model with full DFT calculations on hundreds of binary surface alloys is remarkable. The scheme should therefore provide a fast and effective method for the estimation of oxygen binding energies on a wide variety of transition metal alloys. [Copyright &y& Elsevier]

Abstract: In this paper we present density functional theory (DFT) investigations of the physical, chemical and electronic structure properties of several close-packed surfaces of early transition metal carbides, including β-Mo2C(0001), and the (111) surfaces of TiC, VC, NbC, and TaC. The results are in excellent agreement with experimental values of lattice constants and bulk moduli. The adsorption of atomic hydrogen is used as a probe to compare the chemical properties of various carbide surfaces. Hydrogen adsorbs more strongly to the metal-terminated carbide surfaces than to the corresponding closest-packed pure metal surfaces, due to the tensile strain induced in the carbide surfaces upon incorporation of carbon into the lattice. Hydrogen atoms were found to adsorb more weakly on carbide surfaces than on the corresponding closest-packed pure metal surfaces only when there were surface carbon atoms present, and in some cases very stable C–H species were formed. The DFT results indicated that the hydrogen adsorption energy could be correlated to the d-band center of the carbide surfaces, although the correlation was not as good as our previous studies on bimetallic surfaces. [Copyright &y& Elsevier]

We present extensive density functional theory calculations of the bonding between strands in β-sheets. We identify a significant cooperative effect whereby the interaction increases in strength with the number of strands. We show that the effect is related to a coupling between interstrand bonding and intrastrand elastic properties. It is found that a direct consequence of this coupling is that the pitch of β-sheets should contract with increasing number of strands, and we show that the effect can be observed directly in experimental data from the Protein Data Bank. [ABSTRACT FROM AUTHOR]

We investigate the chemical consequences of a central ligand in the nitrogenase FeMo cofactor using density functional calculations. Several studies have shown that the central ligand most probably is a nitrogen atom, but the consequences for the chemical reactivity of the cofactor are unknown. We investigate several possible routes for insertion of the central nitrogen ligand and conclude that all routes involve barriers and intermediate states, which are inaccessible at ambient conditions. On this basis we suggest that the central nitrogen ligand is present at all times during the reaction. Furthermore, we investigate how the FeMoco with the central ligand can interact with N2 and reduce it. [ABSTRACT FROM AUTHOR]

Based on density functional theory calculations, kinetic measurements, microkinetic and Monte Carlo simulations, thermogravimetric analysis (TGA) experiments, extended X-ray absorption spectroscopy (EXAFS) measurements, and experimental results from the literature, we present a detailed and comprehensive mechanistic picture of the steam reforming process on a Ni catalyst. The complete potential energy diagram for the full reaction is presented and compared to experiments. Structures, energies of all reaction intermediates, and activation barriers are identified. We conclude that there are at least two kinds of active sites with different reactivities for steam reforming: a more active one associated with defect (step) sites, and a less active one associated with close-packed facets. It is further suggested that the nucleation of graphite is initiated at the step sites. We show that additives like potassium, sulfur, and gold preferentially bind to the step sites of Ni, and on this basis it is suggested that the promotion by these additives in terms of a higher tolerance toward graphite formation involves the same basic mechanism: blocking of the step sites. [Copyright &y& Elsevier]

Based on an extensive set of density functional theory calculations it is shown that for a class of catalytic reactions there is a universal, reactant independent relation between the reaction activation energy and the stability of reaction intermediates. This leads directly to a universal relationship between adsorption energies and catalytic activity, which is used to pinpoint what it is that determines the best catalyst for a given reaction. The universality principle rationalizes a number of known facts about catalysts and points to new ways of improving them. [Copyright &y& Elsevier]

The article offers an overview of the study conducted by Loffreda and colleagues regarding the order in which chemical bonds form in molecules bound to a surface of a catalyst. It mentions that researchers have shown that surface-bond energy is a descriptor of reaction selectivity. It mentions that they showed that the order in which various double bonds of unsaturated aldehydes are hydrogenated on a platinum surface can be understood by dividing potential reactions that could occur into groups.

Background Methods Results Conclusion Peripheral nerve blocks may provide better conditions for closed reduction of distal radius fractures as compared to other more frequently used modalities. In this systematic review, we evaluate existing evidence on the effect and harm of peripheral nerve blocks for closed reduction of distal radius fractures in adults.We performed a systematic review with meta‐analysis and trial sequential analysis including trials investigating the use of peripheral nerve blocks for closed reduction of distal radius fractures. Co‐primary outcomes were (1) the quality of the closed reduction measured as the proportion of participants needing surgery afterwards and (2) pain during closed reduction.Six trials (n = 312) met the inclusion criteria. One trial reported on the need for surgery with 4 of 25 participants receiving nerve block compared to 7 of 25 receiving haematoma block needing surgery (RR 0.57, 96.7% CI [0.19; 1.71], p = .50). Four trials reported pain during closed reduction. In a meta‐analysis, pain was not statistically significantly reduced with a nerve block (−2.1 Numeric Rating Scale (NRS) points (0–10), 96.7% CI [−4.4; 0.2], p = .07, tau2 = 5.4, I2 = 97%, TSA‐adj. 95% CI [−11.5; 7.3]). No trial sequential boundaries were crossed, and the required information size was not met. Pre‐planned subgroup analysis on trials evaluating ultrasound guided peripheral nerve blocks (patients = 110) showed a significant decrease in ‘pain during reduction’ (−4.1 NRS, 96.7% CI [−5.5; −2.6], p < .01, tau2 = 0.9, I2 = 80%). All trial results were at high risk of bias and the certainty of the evidence was very low.The certainty of evidence on the effect of peripheral nerve blocks for closed reduction of distal radius fractures is currently very low. Peripheral nerve blocks performed with ultrasound guidance may potentially reduce pain during closed reduction. High‐quality clinical trials are warranted. [ABSTRACT FROM AUTHOR]

Background: Both dexamethasone and dexmedetomidine increase the duration of analgesia of peripheral nerve blocks. The authors hypothesized that combined intravenous dexamethasone and intravenous dexmedetomidine would result in a greater duration of analgesia when compared with intravenous dexamethasone alone and placebo. Methods: The authors randomly allocated participants undergoing surgery of the foot or ankle under general anesthesia and with a combined popliteal (sciatic) and saphenous nerve block to a combination of 12 mg dexamethasone and 1 µg/kg dexmedetomidine, 12 mg dexamethasone, or placebo (saline). The primary outcome was the duration of analgesia measured as the time from block performance until the first sensation of pain in the surgical area as reported by the participant. The authors predefined a 33% difference in the duration of analgesia as clinically relevant. Results: A total of 120 participants from two centers were randomized and 119 analyzed for the primary outcome. The median [interquartile range] duration of analgesia was 1,572 min [1,259 to 1,715] with combined dexamethasone and dexmedetomidine, 1,400 min [1,133 to 1,750] with dexamethasone alone, and 870 min [748 to 1,138] with placebo. Compared with placebo, the duration was greater with combined dexamethasone and dexmedetomidine (difference, 564 min; 98.33% CI, 301 to 794; P < 0.001) and with dexamethasone (difference, 489 min; 98.33% CI, 265 to 706; P < 0.001). The prolongations exceeded the authors' predefined clinically relevant difference. The duration was similar when combined dexamethasone and dexmedetomidine was compared with dexamethasone alone (difference, 61 min; 98.33% CI, –222 to 331; P = 0.614). Conclusions: Dexamethasone with or without dexmedetomidine increased the duration of analgesia in patients undergoing surgery of the foot or ankle with a popliteal (sciatic) and saphenous nerve block. Combined dexamethasone and dexmedetomidine did not increase the duration of analgesia when compared with dexamethasone. This randomized, blinded, placebo-controlled clinical trial assessed the pragmatic outcome of time to first pain in adult patients undergoing surgery of the foot or ankle, showing that IV dexamethasone, with and without IV dexmedetomidine, prolonged analgesia of a sciatic plus saphenous nerve block. IV dexamethasone, with and without IV dexmedetomidine, substantially decreased all pain measures and opioid consumption within the first 24 h postoperatively and increased the duration of the motor block. [ABSTRACT FROM AUTHOR]

Over the past two decades, there has been growing interest in developing catalysts to enable Haber-Bosch ammonia synthesis under milder conditions than currently pertain. Rational catalyst design requires theoretical guidance and clear mechanistic understanding. Recently, a spin-mediated promotion mechanism was proposed to activate traditionally unreactive magnetic materials such as cobalt (Co) for ammonia synthesis by introducing hetero metal atoms bound to the active site of the catalyst surface. We combined theory and experiment to validate this promotion mechanism on a lanthanum (La)/Co system. By conducting model catalyst studies on Co single crystals and mass-selected Co nanoparticles at ambient pressure, we identified the active site for ammonia synthesis as the B5 site of Co steps with La adsorption. The turnover frequency of 0.47 ± 0.03 per second achieved on the La/Co system at 350°C and 1 bar surpasses those of other model catalysts tested under identical conditions. [ABSTRACT FROM AUTHOR]

Background: Current methods of anaesthesia used for closed reduction of distal radial fractures may be insufficient for pain relief and muscle relaxation, potentially compromising reduction quality and patient satisfaction. Peripheral nerve blocks have already been implemented for surgery of wrist fractures and may provide optimal conditions for closed reduction due to complete motor and sensory blockade of the involved nerves. However, existing literature on peripheral nerve blocks for closed reduction is sparse, and no updated systematic review or meta‐analysis exists. Aims: This protocol is developed according to the PRISMA‐P statement. The systematic review and meta‐analysis aim to consolidate the literature regarding the effect and harm of peripheral nerve blocks compared with other anaesthesia modalities for closed reduction of distal radius fractures in adults. Methods: The two primary outcomes are the proportion of participants needing surgery after closed reduction and pain during closed reduction. We will only include randomised clinical trials. Two review authors will each independently screen literature, extract data, and assess risk of bias with Risk of Bias 2 Tool. Meta‐analysis will be carried out with Rstudio. We will also perform a Trial Sequential Analysis. The certainty of evidence will be judged using GRADE guidelines. Discussion: We will use up‐to‐date methodology when conducting the systematic review outlined in this protocol. The results may guide clinicians in their decision‐making regarding the use of anaesthesia for closed reduction of distal radius fractures in adults. [ABSTRACT FROM AUTHOR]

Introduction: This protocol describes a systematic review and meta‐analysis to evaluate the clinical effects of mixing short‐ and long‐acting local anaesthetics in peripheral nerve blocks. Clinicians often combine short‐ and long‐acting local anaesthetics to achieve a briefer onset time. However, this may come with a prize, namely a shorter total duration of the block, which is of clinical importance. Objective: This systematic review aims to strengthen the knowledge of the clinical effects associated with this practice. The primary outcome is the duration of block analgesia. Secondary outcomes are block onset time, sensory and motor block duration. Exploratory outcomes are postoperative pain scores, cumulative 24‐h opioid consumption and the prevalence of serious adverse events. Methods: We will conduct a meta‐analysis of the extracted data, and the risk of bias for each study will be evaluated. We will perform a Trial Sequential Analysis, subgroup, and sensitivity analyses and assess the overall risk of publication bias. Finally, we will evaluate the review using the GRADE principles. [ABSTRACT FROM AUTHOR]

Linear scaling relations have led to an understanding of trends in catalytic activity and selectivity of many reactions in heterogeneous and electro-catalysis. However, linear scaling between the chemisorption energies of any two small molecule adsorbates is not guaranteed. A prominent example is the lack of scaling between the chemisorption energies of carbon and oxygen on transition metal surfaces. In this work, we show that this lack of scaling originates from different re-normalized adsorbate valence energies of lower-lying oxygen vs higher-lying carbon. We develop a model for chemisorption of small molecule adsorbates within the d-band model by combining a modified form of the Newns–Anderson hybridization energy with an effective orthogonalization term. We develop a general descriptor to a priori determine if two adsorbates are likely to scale with each other. [ABSTRACT FROM AUTHOR]

Quantum-mechanical calculations of the reaction rate for dissociative adsorption of N2 on stepped Ru(0001) are presented. Converged six-dimensional quantum calculations for this heavy-atom reaction have been performed using the multiconfiguration time-dependent Hartree method. A potential-energy surface for the transition-state region is constructed from density-functional theory calculations using Shepard interpolation. The quantum results are in very good agreement with the results of the harmonic transition-state theory. In contrast to the findings of previous model calculations on similar systems, the tunneling effect is found to be small. [ABSTRACT FROM AUTHOR]

Summary: The effects of oral dexamethasone on peripheral nerve blocks have not been investigated. We randomly allocated adults scheduled for forearm or hand surgery to oral placebo (n = 61), dexamethasone 12 mg (n = 61) or dexamethasone 24 mg (n = 57) about 45 min before lateral infraclavicular block. Mean (SD) time until first pain after block were: 841 (327) min; 1171 (318) min; and 1256 (395) min, respectively. Mean (98.3%CI) differences in time until first postoperative pain for dexamethasone 24 mg vs. placebo and vs. dexamethasone 12 mg were: 412 (248–577) min, p < 0.001; and 85 (‐78 to 249) min, p = 0.21, respectively. Mean (98.3%CI) difference in time until first postoperative pain for dexamethasone 12 mg vs. placebo was 330 (186–474) min, p < 0.001. Both 24 mg and 12 mg of oral dexamethasone increased the time until first postoperative pain compared with placebo in patients having upper limb surgery under infraclavicular brachial plexus block. [ABSTRACT FROM AUTHOR]

„…︁ Die Suche nach dem Materialgenom – den Charakteristika eines Materials, die seine funktionellen Eigenschaften definieren – hat begonnen, und damit eine neue Ära der Materialforschung, in der große Mengen an Materialdaten zugänglich werden. Man hofft, dass dadurch die Entdeckung neuer Materialien deutlich beschleunigt wird …︁”︁ Lesen Sie mehr dazu im Editorial von J. K. Nørskov und T. Bligaard. [ABSTRACT FROM AUTHOR]

'...︁ The quest for the materials genome-the properties of a material that define its functional properties-has started. This signifies a transition to a new era of materials research where large amounts of materials data become available. The expectation is that this will significantly speed up the discovery of new materials ...︁' Read more in the Editorial by J. K. Nørskov and T. Bligaard. [ABSTRACT FROM AUTHOR]

• Density functional theory suggests new structure for ammonia catalyst active site. • K-promoter stabilizes the N-N transition state and destabilizes late intermediates. • 20 ppm water vapor is detrimental to ammonia production rate at low temperature. • Weak-binding catalysts are less susceptible to oxygen poisoning. • Mitigating oxygen poisoning is essential to low-temperature ammonia synthesis. The Haber-Bosch process has been studied extensively, yet a low-temperature, low-pressure process remains elusive. As has been shown many times, this stems in part from the difficulty of breaking the N-N triple bond. In this work, we highlight an additional reason for the lack of a low-temperature ammonia synthesis process: the effect of oxygen poisoning at low temperature. Using density functional theory (DFT), we have created a new model for the active site of industrial Haber-Bosch catalysts which explicitly includes the potassium promoter. Furthermore, we present a new micro-kinetic model for ammonia synthesis that includes the effect of oxygen poisoning due to trace water content in the input gas stream. Our model agrees well with previous experiments and shows that devising a strategy to avoid oxygen poisoning is crucial to creating a low-temperature Haber-Bosch process. Additionally, the model suggests that using a weaker-binding catalyst is one way to avoid oxygen poisoning if it is impractical to remove all water from the reactor. [ABSTRACT FROM AUTHOR]

It has been a long‐standing goal to find alternative, cost effective catalysts for oxygen reduction reaction (ORR) in fuel cells. Molecular complexes capable of efficiently catalyzing ORR, when supported on a conducting solid surface could provide interesting hybrid materials combining the best of homogeneous and heterogeneous catalysis. We use density functional theory to study the ORR activity of molecular (unsupported) and gold supported 3d metal (II)‐porphycenes (MPc). All the 3d metal‐porphycenes adsorb strongly on the Au(111) support with negative free energy of formation ranging from 1.0–3.0 eV while solvation lowers the energy of molecular MPc by only 0.5 eV compared to the gas phase. These indicate that the 3d MPc are stable and anchored firmly to the gold surface under ORR conditions. Based on our analysis, the gold support enhances the ORR activity in some of the examined MPc systems. We find that the molecular MnPc and FePc are the best ORR electrocatalysts with theoretical overpotentials of 0.44 V and 0.36 V. This work highlights the important role of the support in preserving/increasing the activity of molecular catalyst. The role of conducting solid support in enhancing/preserving the ORR activity of molecular catalysts is investigated with DFT. Such combination makes use of the best of homogeneous and heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

The article discusses a report in the same issue by Suntivich and colleagues regarding the development of metal oxide catalysts for water electrolysis. Researchers determined that their criteria, or descriptor, for the investigation of a series of Earth-abundant transition metal oxides would be the number of occupied orbital states, and found that perovskite-based catalysts were the most efficient for the oxygen evolution reaction. This procedure could lead to new methods for the design and synthesis of catalysts for the purposes of sustainable fuel production and storage.

The article discusses a report within the issue in which researchers take a gold catalysis a step closer toward industrial application. According to the authors, there is an urgent need to discover and implement cleaner chemical transformations in order to develop a chemical industry that is more sustainable. They suggest that catalytic oxidations which produce pure water as the only by-product are the most important reactions.

The article discusses research that introduced the general degree of rate control as a mechanism for characterizing the acceleration of reactions by catalysts. Researchers illustrated this approach through a catalyzed chemical reaction that takes several steps. The overall rate of the reaction is dependent upon minima and maxima in free energy. The stability of reactants, intermediates, and products in the reaction are defined by the minima, while transition states that must be traversed for the reaction to proceed are defined by the maxima. Concepts underlying the transition-state theory are elucidated and adsorption energy is discussed.

Examines the oxidation of carbon monoxide (CO) by gold nanoparticle. Catalysis of CO oxidation reaction; Barrier for carbon dioxide formation; Binding energy of oxygen.

Cohort studies have indicated that avoidance of neuromuscular blocking agents (NMBA) is a risk factor for difficult tracheal intubation. However, the impact of avoiding NMBA on tracheal intubation, possible adverse effects, and postoperative discomfort has not been evaluated in a systematic review of randomised trials. We searched several databases for trials published until January 2017. We included randomised controlled trials comparing the effect of avoiding vs using NMBA. Two independent authors assessed risk of bias and extracted data. The risk of random errors was assessed by trial sequential analysis (TSA). We included 34 trials (3565 participants). In the four trials judged to have low risk of bias, there was an increased risk of difficult tracheal intubation with no use of NMBA [random-effects model, risk ratio (RR) 13.27, 95% confidence interval (CI) 8.19-21.49, P<0.00001, TSA-adjusted CI 1.85-95.04]. The result was confirmed when including all trials, (RR 5.00, 95% CI 3.49-7.15, P<0.00001, TSA-adjusted CI 1.20-20.77). There was a significant risk of upper airway discomfort or injury by avoiding NMBA (RR=1.37, 95% CI 1.09-1.74, P=0.008, TSA-adjusted CI 1.00-1.86). None of the trials reported mortality. Avoiding NMBA was significantly associated with difficult laryngoscopy, (RR 2.54, 95% CI 1.53-4.21, P=0.0003, TSA-adjusted CI 0.27-21.75). In a clinical context, one must balance arguments for using NMBA when performing tracheal intubation. [ABSTRACT FROM AUTHOR]