Active species in chloroaluminate ionic liquids catalyzing low-temperature polyolefin deconstruction.

Chloroaluminate ionic liquids selectively transform (waste) polyolefins into gasoline-range alkanes through tandem cracking-alkylation at temperatures below 100 °C. Further improvement of this process necessitates a deep understanding of the nature of the catalytically active species and the correlated performance in the catalyzing critical reactions for the tandem polyolefin deconstruction with isoalkanes at low temperatures. Here, we address this requirement by determining the nuclearity of the chloroaluminate ions and their interactions with reaction intermediates, combining in situ Al magic-angle spinning nuclear magnetic resonance spectroscopy, in situ Raman spectroscopy, Al K-edge X-ray absorption near edge structure spectroscopy, and catalytic activity measurement.

Methane-HS Reforming Catalyzed by Carbon and Metal Sulfide Stabilized Sulfur Dimers.

HS reforming of methane (HRM) provides a potential strategy to directly utilize sour natural gas for the production of CO-free H and sulfur chemicals. Several carbon allotropes were found to be active and selective for HRM, while the additional presence of transition metals led to further rate enhancements and outstanding stability (e.g.

Synergy of Oxygen Vacancies and Base Sites for Transfer Hydrogenation of Nitroarenes on Ceria Nanorods.

CeO nanorod based catalysts for the base-free synthesis of azoxy-aromatics via transfer hydrogenation of nitroarenes with ethanol as hydrogen donor have been synthesized and investigated. The oxygen vacancies (O ) and base sites are critical for their excellent catalytic properties. The O , i.

Effects of Non-physician Practitioners on Emergency Medicine Physician Resident Education.

Introduction: The effects of non-physician practitioners (NPP) such as physician assistants and nurse practitioners on the education of emergency medicine (EM) residents have not previously been specifically evaluated. Emergency medicine societies have made policy statements regarding NPP presence in EM residencies without the benefit of empiric studies.

Methods: A cross-sectional, mixed methods questionnaire with strong validity evidence was distributed to current EM residents who were members of a large national society, the American Academy of Emergency Medicine Resident and Student Association (AAEM/RSA), between June 4-July 5, 2021.

Factorization of quaternionic polynomials of bi-degree (n,1).

We consider polynomials of bi-degree (, 1) over the skew field of quaternions where the indeterminates commute with each other and with all coefficients. Polynomials of this type do not generally admit factorizations. We recall a necessary and sufficient condition for existence of a factorization with univariate linear factors that has originally been stated by Skopenkov and Krasauskas.

Influence of 1-Butene Adsorption on the Dimerization Activity of Single Metal Cations on UiO-66 Nodes.

Grafting metal cations to missing linker defect sites in zirconium-based metal-organic frameworks, such as UiO-66, produces a uniquely well-defined and homotopic catalytically active site. We present here the synthesis and characterization of a group of UiO-66-supported metal catalysts, M-UiO-66 (M = Ni, Co, Cu, and Cr), for the catalytic dimerization of alkenes. The hydrogen-deuterium exchange via deuterium oxide adsorption followed by infrared spectroscopy showed that the last molecular water ligand desorbs from the sites after evacuation at 300 °C leading to M(OH)-UiO-66 structures.

Impact of hydronium ions on the Pd-catalyzed furfural hydrogenation.

In aqueous mediums, the chemical environment for catalytic reactions is not only comprised of water molecules but also of corresponding ionized species, i.e., hydronium ions, which can impact the mechanism and kinetics of a reaction.

Maximum Impact of Ionic Strength on Acid-Catalyzed Reaction Rates Induced by a Zeolite Microporous Environment.

The intracrystalline ionic environment in microporous zeolite can remarkably modify the excess chemical potential of adsorbed reactants and transition states, thereby influencing the catalytic turnover rates. However, a limit of the rate enhancement for aqueous-phase dehydration of alcohols appears to exist for zeolites with high ionic strength. The origin of such limitation has been hypothesized to be caused by the spatial constraints in the pores via, e.

Distal and Proximal Predictors of Rehospitalization Over 10 Years Among Survivors of TBI: A National Institute on Disability, Independent Living, and Rehabilitation Research Traumatic Brain Injury Model Systems Study.

Objective: To describe the rates and causes of rehospitalization over a 10-year period following a moderate-severe traumatic brain injury (TBI) utilizing the Healthcare Cost and Utilization Project (HCUP) diagnostic coding scheme.

Setting: TBI Model Systems centers.

Participants: Individuals 16 years and older with a primary diagnosis of TBI.

Highly Active and Selective Sites for Propane Dehydrogenation in Zeolite Ga-BEA.

A highly selective Ga-modified zeolite BEA for propane dehydrogenation has been synthesized by grafting Ga on Zn-BEA followed by removal of Zn in the presence of H. A propene selectivity of 82% at 19% propane conversion illustrates the high selectivity at 813 K. The kinetic model of the catalyzed dehydrogenation including the elementary steps of propane adsorption, first and second C-H bond cleavage, and propene and H desorption demonstrates that the propane dehydrogenation rate is determined by the first C-H bond cleavage at low , while at high , the rate is limited by the desorption of H.

Caregiver Characteristics of Adults with Acute Traumatic Brain Injury in the United States and Latin America.

Objectives: To compare characteristics of caregivers of adults with acute traumatic brain injury (TBI) in the U.S. and Latin America (Mexico and Colombia).

Controlling Reaction Routes in Noble-Metal-Catalyzed Conversion of Aryl Ethers.

Hydrogenolysis and hydrolysis of aryl ethers in the liquid phase are important reactions for accessing functionalized cyclic compounds from renewable feedstocks. On supported noble metals, hydrogenolysis is initiated by a hydrogen addition to the aromatic ring followed by C-O bond cleavage. In water, hydrolysis and hydrogenolysis proceed by partial hydrogenation of the aromatic ring prior to water or hydrogen insertion.

Impact of the Local Concentration of Hydronium Ions at Tungstate Surfaces for Acid-Catalyzed Alcohol Dehydration.

Tungstate domains supported on ZrO, AlO, TiO, and activated carbon drastically influence the hydronium-ion-catalyzed aqueous-phase dehydration of alcohols. For all catalysts, the rate of cyclohexanol dehydration normalized to the concentration of Brønsted acid sites (turnover frequencies, TOFs) was lower for monotungstates than for polytungstates and larger crystallites of WO. TOFs were constant when reaching or exceeding the monolayer coverage of tungstate, irrespective of the specific nature of surface structures that continuously evolve with the surface W loading.

Ventricular activation patterns during intrinsic conduction and right ventricular pacing in cardiac resynchronization therapy patients.

Background: Cardiac resynchronization therapy (CRT) involves stimulation of both right ventricle (RV) and left ventricle (LV). LV pacing from the sites of delayed electrical activation improves CRT response. The RV-LV conduction is typically measured in intrinsic rhythm.

Listeria monocytogenes infection rewires host metabolism with regulatory input from type I interferons.

Listeria monocytogenes (L. monocytogenes) is a food-borne bacterial pathogen. Innate immunity to L.

Cellular export of sugars and amino acids: role in feeding other cells and organisms.

Sucrose, hexoses, and raffinose play key roles in the plant metabolism. Sucrose and raffinose, produced by photosynthesis, are translocated from leaves to flowers, developing seeds and roots. Translocation occurs in the sieve elements or sieve tubes of angiosperms.

Confinement effects and acid strength in zeolites.

Chemical reactivity and sorption in zeolites are coupled to confinement and-to a lesser extent-to the acid strength of Brønsted acid sites (BAS). In presence of water the zeolite Brønsted acid sites eventually convert into hydronium ions. The gradual transition from zeolite Brønsted acid sites to hydronium ions in zeolites of varying pore size is examined by ab initio molecular dynamics combined with enhanced sampling based on Well-Tempered Metadynamics and a recently developed set of collective variables.

Role of the ionic environment in enhancing the activity of reacting molecules in zeolite pores.

Tailoring the molecular environment around catalytically active sites allows for the enhancement of catalytic reactivity through a hitherto unexplored pathway. In zeolites, the presence of water creates an ionic environment via the formation of hydrated hydronium ions and the negatively charged framework aluminum tetrahedra. The high density of cation-anion pairs determined by the aluminum concentration of a zeolite induces a high local ionic strength that increases the excess chemical potential of sorbed and uncharged organic reactants.

Distinct identities of leaf phloem cells revealed by single cell transcriptomics.

The leaf vasculature plays a key role in solute translocation. Veins consist of at least seven distinct cell types, with specific roles in transport, metabolism, and signaling. Little is known about leaf vascular cells, in particular the phloem parenchyma (PP).

New Perspective for Soft Tissue Closure in Medication-Related Osteonecrosis of the Jaw (MRONJ) Using Barbed Sutures.

The aim of this study was to compare the effectiveness of barbed versus smooth sutures for soft tissue closure of exposed jawbone sites in medication-related osteonecrosis of the jaw (MRONJ) patients. Exposed necrotic jawbone sites surgically managed by intraoral soft tissue closure were evaluated. Either barbed sutures (Stratafix™ or V-Loc™) together with Prolene or Vicryl sutures were used.

No antiarrhythmic effect of direct oral anticoagulants versus vitamin K antagonists in paroxysmal atrial fibrillation patients undergoing catheter ablation.

Introduction: Direct oral anticoagulants (DOACs) are superior to vitamin K antagonists (VKAs) for the prevention of stroke in atrial fibrillation (AF) patients with elevated stroke risk. Possible antiarrhythmic effects of DOACs have been discussed. We analyzed impact of DOAC treatment on recurrence-free survival after AF catheter ablation.

The PI3K pathway preserves metabolic health through MARCO-dependent lipid uptake by adipose tissue macrophages.

Adipose tissue macrophages (ATMs) display tremendous heterogeneity depending on signals in their local microenvironment and contribute to the pathogenesis of obesity. The phosphoinositide 3-kinase (PI3K) signalling pathway, antagonized by the phosphatase and tensin homologue (PTEN), is important for metabolic responses to obesity. We hypothesized that fluctuations in macrophage-intrinsic PI3K activity via PTEN could alter the trajectory of metabolic disease by driving distinct ATM populations.

Directing the Rate-Enhancement for Hydronium Ion Catalyzed Dehydration via Organization of Alkanols in Nanoscopic Confinements.

Alkanol dehydration rates catalyzed by hydronium ions are enhanced by the dimensions of steric confinements of zeolite pores as well as by intraporous intermolecular interactions with other alkanols. The higher rates with zeolite MFI having pores smaller than those of zeolite BEA for dehydration of secondary alkanols, 3-heptanol and 2-methyl-3-hexanol, is caused by the lower activation enthalpy in the tighter confinements of MFI that offsets a less positive activation entropy. The higher activity in BEA than in MFI for dehydration of a tertiary alkanol, 2-methyl-2-hexanol, is primarily attributed to the reduction of the activation enthalpy by stabilizing intraporous interactions of the C -H transition state with surrounding alcohol molecules.

Electrocatalytic Hydrogenation of Biomass-Derived Organics: A Review.

Sustainable energy generation calls for a shift away from centralized, high-temperature, energy-intensive processes to decentralized, low-temperature conversions that can be powered by electricity produced from renewable sources. Electrocatalytic conversion of biomass-derived feedstocks would allow carbon recycling of distributed, energy-poor resources in the absence of sinks and sources of high-grade heat. Selective, efficient electrocatalysts that operate at low temperatures are needed for electrocatalytic hydrogenation (ECH) to upgrade the feedstocks.

Hydrogen Bonding Enhances the Electrochemical Hydrogenation of Benzaldehyde in the Aqueous Phase.

The hydrogenation of benzaldehyde to benzyl alcohol on carbon-supported metals in water, enabled by an external potential, is markedly promoted by polarization of the functional groups. The presence of polar co-adsorbates, such as substituted phenols, enhances the hydrogenation rate of the aldehyde by two effects, that is, polarizing the carbonyl group and increasing the probability of forming a transition state for H addition. These two effects enable a hydrogenation route, in which phenol acts as a conduit for proton addition, with a higher rate than the direct proton transfer from hydronium ions.