Ionic liquids (ILs) have been extensively explored in controlling the selectivity and stability of metal nanoparticles and/or classical heterogeneous catalysts for the hydrogenation of aromatics. ILs ...provide a protective layer to metal surface catalysts and a physical barrier controlling the access of substrates/intermediates/products on the nanoconfined catalysts, acting as an electronic and geometrical modifier of the catalytic active sites. As a result, this allows the stability and electronic/geometrical properties of the catalyst to be modulated. The IL layers also allow nano‐environments to be designed for encapsulation and to change the kinetic/thermodynamic of the process compared to those reactions performed in classical heterogeneous catalysis. We will focus on the physical, geometric and electronic effects imposed by the IL on metal nanoparticles and classical heterogeneous catalysts on activity and selectivity in the hydrogenation of arenes, in particular benzene.
Eu gosto muito de Arenes: The physical, geometric and electronic effects imposed by ionic liquids on metal surface catalysts on activity and selectivity in the hydrogenation of arenes are discussed in light of recent reports.
A series of first row metal complexes (Co, Ni and Cu) containing commercial nitrogen ligands were synthetized and used as catalyst in the cycloaddition of CO
2
to epoxides. The reaction was carried ...out in ionic liquids based on 1-
n
-butyl-3-methylimidazolium as solvents. Best catalytic results were achieved with Co catalysts in 1-
n
-butyl-3-methylimidazolium tetrafluoroborate (BMIm.BF
4
). Under optimized reaction conditions cyclic carbonates were selectively obtained with good to excellent yields, presenting a reliable alternative to synthetize the product using low cost and abundant catalytic system containing a common ligand as ethylenediamine. Finally, macrocycle effects where studied in each case comparing the conversion rates obtained by using ethylenediamine and 1,4,8,11-tetraazacyclotetradecane.
Graphical Abstract
We present detailed ONIOM(ωB97X-D:PM6) calculations for the formation mechanism of novel composites combining protonic mordenites (H-MOR) with various ionic liquids: 1,3-dimethyl-imidazolium chloride ...MMImCl, 1-ethyl-3-methyl-imidazolium chloride EMImCl; 1-methyl-3-propyl-imidazolium chloride PMImCl; 1-butyl-3-methyl-imidazolium chloride BMImCl, 1-(2-hydroxyethyl)-3-methyl-imidazolium chloride HEMImCl, 1,3-dimethyl-1,3,2-diazasilolium chloride MMSiNCl, and 1,3-dimethyl-1,3-diphospholium chloride MMPPCl. The most feasible M-MOR formation mechanism (M+ = MMIm+, EMIm+, PMIm+, BMIm+, HEMIm+, MMSiN+ MMPP+) involves an ion exchange at the T4O10 position favoring the isolation of a minimal number of M+ isomers (i.e., conformational traps). The interaction of these M-MOR composites with pollutant gases has afterward been evaluated. Among the studied sytems, EMIm-MOR and HEMIm-MOR present electronic and steric conditions for potential applications in gas separation, capture, and storage (H2 and H2S). The H-MOR framework exhibits two structural conformers with the HEMIm+ cation in the confined space. Both, the MOR-T4O10-HEMIm and MOR-T4O10-HEMImHB conformers, interconvert by a dynamic equilibrium with a transition state MOR-T4O10-TS1 acting as a conformational switch (▪-▪) that selectively recognizes and captures H2S through a plier-like conformation.
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•In silico design of novel composites combining Ionic Liquids with mordenite (MOR) was examined.•A composites formation mechanism that involves the ion exchange of H+ by Imidazolium-based Ionic Liquid cation on T4O10 position in H-MOR.•The existence of conformational traps within the mordenite framework was demonstrated.•A new molecular H2S recognition/capture mechanism using HEMIm-MOR composite was proposed.
The effect of the shape of rhodium nanoparticles impregnated on TiO2 on photocatalytic hydrogen generation using methanol as a sacrificial reagent has been investigated by using a simple home-made ...UV-LED light strip reactor to activate the catalyst surface. For rhodium nanocubes, the normalised rate of H2 production was 22.4 mmol h−1 m−2 at 365 nm and 7.5 mmol h−1 m−2 at 400 nm. The normalised activity/surface area of the studied Rh nanoparticles showed a trend that led to establishing a relationship between the exposed 100 facets and photocatalytic activity. The Rh shape-dependent H2 production follows a trend of cubic > spherical > octahedral, which is associated with a higher surface energy of the Rh nanoparticles.
Software-Defined Networking (or SDN), since its creation and subsequent adoption, has promised to be the solution to network infrastructure management, configuration, and performance problems using ...techniques suchas programmability, Open-hardware with programmatic capabilities, extreme agility, in addition to the use of secure Graphical Interfaces/APIs that provide full visibility and infrastructure telemetry. This doctoral thesis takes a look at the evolution of data networks towards the SDN paradigm and its various adoptions (SD-Access, SD-Data Center and SD-WAN) in order to verify its ease of implementation, for which the fundamentals of these technologies are addressed, starting from what decoupling of the Control Plane from the Data Plane in network equipment implies, to the concept of cultural and technological change called NetDevOps, essential for the agile SDN ecosystem to work properly, going through the analysis of next-generation standardized protocols that allow the implementation of these environments in real networks: LISP, VXLAN, OMP and Segment-Routing, developing at the same time proofs of concept (PoCs) in emulation environments and with physical equipment, thus closing the investigative process that validates the integration of SDN-based programmability with traditional networks, this being precisely the greatest contribution of the present research.
Purpose
Cholelithiasis is an issue in bariatric surgery patients. The incidence of cholelithiasis is increased in morbidly obese patients. After bariatric surgery, the management maybe sometimes ...challenging. There is no consensus about how to deal with cholelithiasis prior to bariatric surgery.
Materials and Methods
A retrospective review from our prospectively collected bariatric surgery database. Primary bariatric procedures from 2009 to 2020 were included. Prevalence of cholelithiasis and its management prior to bariatric surgery and the incidence and management of postoperative biliary events were analyzed.
Results
Over 1445 patients analyzed, preoperatively cholelithiasis was found in 153 (10.58%), and 68 out of them (44.44%) were symptomatic. Seventy-six patients had a concomitant cholecystectomy. In those cases, the bariatric procedure did not show increased operative time, length of stay, morbidity, or mortality compared to the rest of primary bariatric procedures. Twelve patients (15.58%) with previous cholelithiasis and no concomitant cholecystectomy presented any kind of biliary event and required cholecystectomy. De novo cholelithiasis rate requiring cholecystectomy was 3.86%. Postoperative biliary events both in de novo and persistent cholelithiasis population did not show any difference between the type of surgery, weight loss, and other characteristics.
Conclusions
Cholelithiasis was present in 10.58% of our primary bariatric surgery population. Concomitant cholecystectomy was safe in our series. Non-surgical management of asymptomatic cholelithiasis did not lead to a higher risk of postoperative biliary events. The global postoperative cholecystectomy rate was equivalent to the general population.
Graphical abstract
The generation of energy by thermoelectric plants powered by biomass in Brazil has grown by ∼3% in the last three years. In 2016, 8.8% of the electric energy in Brazil was generated using biomass as ...an input. However, the generation of residues and the possibility of reapproaching have motivated the planning and uses of electrochemical processes to evaluate the obtained gases (mainly hydrogen and carbon monoxide) as clean energy sources. Although thermochemical processes using biomass as an energy source already exist, few reports regarding the study of this process through electrolysis are available. Herein, we describe a water electrolysis process using sugarcane bagasse, rice husk, and malt bagasse as biomass residues to obtain gases with potential uses as clean energy sources and analyze the mass concentration influences on the behavior of the electrochemical solution. Tafel and cyclic voltammetry analyzes showed a tendency to decrease the kinetics and current of the system with the increase of the biomass residue concentration in the solution. In contrast, sugarcane bagasse concentrations of 0.1%–1% increase the current. The faradaic efficiency and partial current density analysis confirm the results obtained from cyclic voltammetry for hydrogen production, with less faradaic efficiency for hydrogen and reduced current values in the system when the biomass residue concentration is higher. The production efficiency of carbon monoxide formed at the anode increases with the concentration for sugarcane bagasse (2.01–5.21 μA/cm2) with 1% of the biomass in solution.
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The potential impact of genetically modified (GM) crops on biodiversity is one of the main concerns in an environmental risk assessment (ERA). The likelihood of outcrossing and pollen‐mediated gene ...flow from GM crops and non‐GM crops are explained by the same principles and depend primarily on the biology of the species. We conducted a national‐scale study of the likelihood of outcrossing between 11 GM crops and vascular plants in Chile by use of a systematized database that included cultivated, introduced and native plant species in Chile. The database included geographical distributions and key biological and agronomical characteristics for 3505 introduced, 4993 native and 257 cultivated (of which 11 were native and 246 were introduced) plant species. Out of the considered GM crops (cotton, soya bean, maize, grape, wheat, rice, sugar beet, alfalfa, canola, tomato and potato), only potato and tomato presented native relatives (66 species total). Introduced relative species showed that three GM groups were formed having: a) up to one introduced relative (cotton and soya bean), b) up to two (rice, grape, maize and wheat) and c) from two to seven (sugar beet, alfalfa, canola, tomato and potato). In particular, GM crops presenting introduced noncultivated relative species were canola (1 relative species), alfalfa (up to 4), rice (1), tomato (up to 2) and potato (up to 2). The outcrossing potential between species OP; scaled from ‘very low’ (1) to ‘very high’ (5) was developed, showing medium OPs (3) for GM–native relative interactions when they occurred, low (2) for GMs and introduced noncultivated and high (4) for the grape‐Vitis vinifera GM–introduced cultivated interaction. This analytical tool might be useful for future ERA for unconfined GM crop release in Chile.
Commercial bulk powder of SiC and SHS-synthesized SiC nanowires were studied. Gold nanoparticles were deposited onto a surface of both samples. Basic properties, such as crystalline structure, phase ...composition, morphology and photocatalytic activity with the chromatographic analysis of the reaction products, were determined. Obtained silicon carbides are crystalline materials of hexagonal (commercial SiC) and cubic (synthesized SiC nanowires) structures. The presence of gold nanoparticles was proven through Raman spectroscopy, inductively coupled plasma mass spectrometry and transmission electron microscopy. No gold phase was detected as a separate crystalline component in both Au-modified samples. The neat nanowires were indicated as a catalyst rather accumulating intermediate organic substances than commercial SiC which enables shifting equilibrium to the generation of gaseous products (CO and CH
4
). The gold-containing SiC nanowires demonstrated an essential enhancement of photocatalytic activity keeping Au nanoparticles on the surface after the reaction.
A series of related acetylacetonate–carbonyl–rhodium compounds substituted by functionalized phosphines has been prepared in good to excellent yields by the reaction of Rh(acac)(CO)2 (acac is ...acetylacetonate) with the corresponding allyl‐, cyanomethyl‐ or cyanoethyl‐substituted phosphines. All compounds were fully characterized by 31P, 1H, 13C NMR and IR spectroscopy. The X‐ray structures of (acetylacetonato‐κ2O,O′)(tert‐butylphosphanedicarbonitrile‐κP)carbonylrhodium(I), Rh(C5H7O2)(CO)(C8H13N2) or Rh(acac)(CO)(tBuP(CH2CN)2} (2b), (acetylacetonato‐κ2O,O′)carbonyl3‐(diphenylphosphanyl)propanenitrile‐κPrhodium(I), Rh(C5H7O2)(C15H14N)(CO) or Rh(acac)(CO){Ph2P(CH2CH2CN)} (2h), and (acetylacetonato‐κ2O,O′)carbonyl3‐(di‐tert‐butylphosphanyl)propanenitrile‐κPrhodium(I), Rh(C5H7O2)(C11H22N)(CO) or Rh(acac)(CO){tBu2P(CH2CH2CN)} (2i), showed a square‐planar geometry around the Rh atom with a significant trans influence over the acetylacetonate moiety, evidenced by long Rh—O bond lengths as expected for poor π‐acceptor phosphines. The Rh—P distances displayed an inverse linear dependence with the coupling constants JP‐Rh and the IR ν(Ctriple‐bondO) bands, which accounts for the Rh—P electronic bonding feature (poor π‐acceptors) of these complexes. A combined study from density functional theory (DFT) calculations and an evaluation of the intramolecular H…Rh contacts from X‐ray diffraction data allowed a comparison of the conformational preferences of these complexes in the solid state versus the isolated compounds in the gas phase. For 2b, 2h and 2i, an energy‐framework study evidenced that the crystal structures are mainly governed by dispersive energy. In fact, strong pairwise molecular dispersive interactions are responsible for the columnar arrangement observed in these complexes. A Hirshfeld surface analysis employing three‐dimensional molecular surface contours and two‐dimensional fingerprint plots indicated that the structures are stabilized by H…H, C…H, H…O, H…N and H…Rh intermolecular interactions.
A set of rhodium complexes involving functionalized allyl‐ and cyanoalkylphosphines shows an inverse dependence between the Rh—P distance and the coupling constant JP‐Rh and the IR ν(Ctriple‐bondO) bands, which account for the poor π‐acceptor Rh—P electronic bonding feature of these ligands.
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