Effect of Impurities on the Initiation of the Methanol-to-Olefins Process: Kinetic Modeling Based on Ab Initio Rate Constants

The relevance of a selection of organic impurities for the initiation of the MTO process was quantified in a kinetic model comprising 107 elementary steps with ab initio computed reaction barriers (MP2:DFT). This model includes a representative part of the autocatalytic olefin cycle as well as a direct initiation mechanism starting from methanol through CO-mediated direct C–C bond formation. We find that the effect of different impurities on the olefin evolution varies with the type of impurity and their partial pressures. The reactivity of the considered impurities for initiating the olefin cycle increases in the order formaldehyde < di-methoxy methane < CO < methyl acetate < ethanol < ethene < propene. In our kinetic model, already extremely low quantities of impurities such as ethanol lead to faster initiation than through direct C–C bond formation which only matters in complete absence of impurities. Graphic Abstract: [Figure not available: see fulltext.

Theoretical investigation of the olefin cycle in H-SSZ-13 for the ethanol-to-olefins process using ab initio calculations and kinetic modeling

The formation of the hydrocarbon pool (HCP) in the ethanol-to-olefins (ETO) process catalyzed by H-SSZ-13 is studied in a kinetic model with ab initio computed reaction barriers. Free energy barriers are computed using density functional theory (DFT) and post-Hartree–Fock methods with a complete basis set extrapolation applied to a hierarchy of periodic and cluster models. The kinetic model includes ethanol (EtOH) dehydration to ethene as well as olefin ethylations up to hexene isomers and the corresponding cracking reactions. Ethylation of ethene and of products thereof leads only to even-numbered olefins, while cracking can lead to propene and thus initiate the formation of olefins with an odd number of carbon atoms. During EtOH dehydration at 473.15 K we observe diethyl ether (DEE) formation for a short period of time where the DEE selectivity decreases monotonically with increasing EtOH conversion. At 673.15 K we find that EtOH dehydration occurs much faster than ethylation of the formed ethene, which takes considerably longer due to higher free energy barriers. Hexene isomers form on the same time scale as butene, where branched isomers are favored with 2-methyl-pentene isomers contributing most to the formation of propene through cracking. As in the methanol-to-olefins (MTO) process, the most relevant alkylation pathway is the stepwise mechanism via surface alkoxy species (SAS) on the zeolite catalyst. A comparison of ethylation with methylation barriers of up to heptene isomers forming nonene and octene isomers, respectively, shows that ethylation barriers are lower by around 11 kJ mol$^{-1}$ on average

In Search of Benchmarking for Mortality Following Multiple Trauma: A Swiss Trauma Center Experience

Background: The manifestations associated with non-survival after multiple trauma may vary importantly between countries and institutions. The aim of the present study was to assess the quality of performance by comparing actual mortality rates to the literature. Methods: The study involved evaluation of a prospective consecutive multiple trauma cohort (injury severity score, ISS>16) primarily admitted to a university hospital. Univariate and multivariate testing of routine parameters and scores, such as the Trauma and Injury Severity Score (TRISS), was used to determine their predictive powers for mortality. Results: The 30-day mortality of 22.8% (n=54) exactly matched predicted TRISS versions of Champion or the Major Trauma Outcome Study for our 237 multiple trauma patients (42.8±20.9years; ISS 29.5±11.5). Univariate analysis revealed significant differences between survivors and non-survivors when compared for age, ISS, Glasgow coma scale (GCS), pulse oximeter saturation (SapO2), hemoglobin, prothrombin time, and lactate. In multivariate analysis, age, ISS, and GCS (P<0.001 each) functioned as major independent prognostic parameters of both 24h and 30-day mortality. Various TRISS versions hardly differed in their precision (area under the curve [AUC] 0.83-0.84), but they did differ considerably in their level of requirement, with the TRISS using newer National Trauma Data Bank coefficients (NTDB-TRISS) offering the highest target benchmark (predicted mortality 13%, Z value -5.7) in the prediction of 30-day mortality. Conclusions: Because of the current lack of a single, internationally accepted scoring system for the prediction of mortality after multiple trauma, the comparison of outcomes between medical centers remains unreliable. To achieve effective quality control, a practical benchmarking model, such as the TRISS-NTDB, should be used worldwid

Combining Theoretical and Experimental Methods to Probe Confinement within Microporous Solid Acid Catalysts for Alcohol Dehydration

Catalytic transformations play a vital role in the implementation of chemical technologies, particularly as society shifts from fossil-fuel-based feedstocks to more renewable bio-based systems. The dehydration of short-chain alcohols using solid acid catalysts is of great interest for the fuel, polymer, and pharmaceutical industries. Microporous frameworks, such as aluminophosphates, are well-suited to such processes, as their framework channels and pores are a similar size to the small alcohols considered, with many different topologies to consider. However, the framework and acid site strength are typically linked, making it challenging to study just one of these factors. In this work, we compare two different silicon-doped aluminophosphates, SAPO-34 and SAPO-5, for alcohol dehydration with the aim of decoupling the influence of acid site strength and the influence of confinement, both of which are key factors in nanoporous catalysis. By varying the alcohol size from ethanol, 1-propanol, and 2-propanol, the acid sites are constant, while the confinement is altered. The experimental catalytic dehydration results reveal that the small-pore SAPO-34 behaves differently to the larger-pore SAPO-5. The former primarily forms alkenes, while the latter favors ether formation. Combining our catalytic findings with density functional theory investigations suggests that the formation of surface alkoxy species plays a pivotal role in the reaction pathway, but the exact energy barriers are strongly influenced by pore structure. To provide a holistic view of the reaction, our work is complemented with molecular dynamics simulations to explore how the diffusion of different species plays a key role in product selectivity, specifically focusing on the role of ether mobility in influencing the reaction mechanism. We conclude that confinement plays a significant role in molecular diffusion and the reaction mechanism translating to notable catalytic differences between the molecules, providing valuable information for future catalyst design

One Pot Cooperation of Single Atom Rh and Ru Solid Catalysts for a Selective Tandem Olefin Isomerization - Hydrosilylation Process

[EN] Realizing the full potential of oxide-supported single-atom metal catalysts (SACs) is key to successfully bridge the gap between the fields of homogeneous and heterogeneous catalysis. Here we show that the one-pot combination of Ru-1/CeO2 and Rh-1/CeO2 SACs enables a highly selective olefin isomerization-hydrosilylation tandem process, hitherto restricted to molecular catalysts in solution. Individually, monoatomic Ru and Rh sites show a remarkable reaction specificity for olefin double-bond migration and anti-Markovnikov alpha-olefin hydrosilylation, respectively. First-principles DFT calculations ascribe such selectivity to differences in the binding strength of the olefin substrate to the monoatomic metal centers. The single-pot cooperation of the two SACs allows the production of terminal organosilane compounds with high regio-selectivity (>95 %) even from industrially-relevant complex mixtures of terminal and internal olefins, alongside a straightforward catalyst recycling and reuse. These results demonstrate the significance of oxide-supported single-atom metal catalysts in tandem catalytic reactions, which are central for the intensification of chemical processes.X-ray absorption experiments were performed at the ALBA Synchrotron Light Source (Spain), experiments 2018082961 and 2019023278. L. Simonelli and C. Marini (CLAESSALBA beamline) are thanked for beamline setup. E. Andres, M. E. Martinez, M. Garcia, and I. Lopez (ITQ), are acknowledged for their assistance with XAS experiments. J. Buscher, J. Ternedien, B. Spliethoff, and C. Wirtz (MPI-KOFO) are acknowledged for the performance of XPS, XRD, BF-TEM and 2H NMR experiments, respectively. I. C. de Freitas (MPIKOFO) is thanked for assistance with Raman spectroscopy. J. M. Salas (ITQ) is gratefully acknowledged for his contribution to CO-FTIR experiments. J. J. Barnes and Shell (Amsterdam) are acknowledged for kindly providing an industrial olefin mixture as feed. Authors are thankful to F. Schuth for the provision of lab space and continued support. Part of the HRSTEM and EDX-STEM studies were conducted at the Laboratorio de Microscopias Avanzadas, Instituto de Nanociencia de Aragon, Universidad de Zaragoza, Spain. R.A. gratefully acknowledges the support from the Spanish Ministry of Economy and Competitiveness (MINECO) through project grant MAT2016-79776-P (AEI/FEDER, UE) and from the European Union H2020 programs "ESTEEM3" (823717). The authors acknowledge support by the state of Baden-Wurttemberg through bwHPC (bwUnicluster and JUSTUS, RV bw17D01), by the GRK 2450 and by the Helmholtz Association. This research received funding from the Max Planck Society, and the Fonds der Chemische Industrie of Germany. Funding from the Spanish Ministry of Science, Innovation and Universities (Severo Ochoa program SEV-2016-0683 and grant RTI2018096399-A-I00) is also acknowledged. B.B.S. acknowledges the Alexander von Humboldt Foundation for a postdoctoral scholarship. Open Access funding is provided by the Max Planck Society.Sarma, BB.; Kim, J.; Amsler, J.; Agostini, G.; Weidenthaler, C.; Pfaender, N.; Arenal, R.... (2020). One Pot Cooperation of Single Atom Rh and Ru Solid Catalysts for a Selective Tandem Olefin Isomerization - Hydrosilylation Process. Angewandte Chemie International Edition. 59(14):5806-5815. https://doi.org/10.1002/anie.201915255S580658155914Liang, S., Hao, C., & Shi, Y. (2015). The Power of Single-Atom Catalysis. ChemCatChem, 7(17), 2559-2567. doi:10.1002/cctc.201500363Liu, J. (2016). Catalysis by Supported Single Metal Atoms. 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Early Switch from Intravenous to Oral Antibiotics in Skin- and Soft-tissue Infections: An Algorithm-based Prospective Multicentre Pilot Trial.

BACKGROUND: In hospitalized patients with skin and soft tissue infections (SSTIs), intravenous (IV) empiric antibiotic treatment is initiated. The best time point for switching from IV to oral treatment is unknown. We used an algorithm-based decision tree for the switch from IV to oral antibiotics within 48 hours and aimed to investigate the treatment outcome of this concept. METHODS: In a nonrandomized trial, we prospectively enrolled 128 patients hospitalized with SSTI from July 2019 to May 2021 at 3 institutions. Clinical and biochemical response data during the first week and at follow-up after 30 days were analyzed. Patients fulfilling criteria for the switch from IV to oral antibiotics were assigned to the intervention group. The primary outcome was a composite definition consisting of the proportion of patients with clinical failure or death of any cause. RESULTS: Ninety-seven (75.8%) patients were assigned to the intervention group. All of them showed signs of clinical improvement (ie, absence of fever or reduction of pain) within 48 hours of IV treatment, irrespective of erythema finding or biochemical response. The median total antibiotic treatment duration was 11 (interquartile range [IQR], 9–13) days in the invention group and 15 (IQR, 11–24) days in the nonintervention group (P < .001). The median duration of hospitalization was 5 (IQR, 4–6) days in the intervention group and 8 (IQR, 6–12) days in the nonintervention group (P < .001). There were 5 (5.2%) failures in the intervention group and 1 (3.2%) in the nonintervention group after a median follow-up of 37 days. CONCLUSIONS: In this pilot trial, the proposed decision algorithm for early switch from IV to oral antibiotics for SSTI treatment was successful in 95% of cases. Clinical Trials Registration. ISRCTN1524549

Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

Impacts of the Tropical Pacific/Indian Oceans on the Seasonal Cycle of the West African Monsoon

The current consensus is that drought has developed in the Sahel during the second half of the twentieth century as a result of remote effects of oceanic anomalies amplified by local land–atmosphere interactions. This paper focuses on the impacts of oceanic anomalies upon West African climate and specifically aims to identify those from SST anomalies in the Pacific/Indian Oceans during spring and summer seasons, when they were significant. Idealized sensitivity experiments are performed with four atmospheric general circulation models (AGCMs). The prescribed SST patterns used in the AGCMs are based on the leading mode of covariability between SST anomalies over the Pacific/Indian Oceans and summer rainfall over West Africa. The results show that such oceanic anomalies in the Pacific/Indian Ocean lead to a northward shift of an anomalous dry belt from the Gulf of Guinea to the Sahel as the season advances. In the Sahel, the magnitude of rainfall anomalies is comparable to that obtained by other authors using SST anomalies confined to the proximity of the Atlantic Ocean. The mechanism connecting the Pacific/Indian SST anomalies with West African rainfall has a strong seasonal cycle. In spring (May and June), anomalous subsidence develops over both the Maritime Continent and the equatorial Atlantic in response to the enhanced equatorial heating. Precipitation increases over continental West Africa in association with stronger zonal convergence of moisture. In addition, precipitation decreases over the Gulf of Guinea. During the monsoon peak (July and August), the SST anomalies move westward over the equatorial Pacific and the two regions where subsidence occurred earlier in the seasons merge over West Africa. The monsoon weakens and rainfall decreases over the Sahel, especially in August.Peer reviewe