Display omitted
•CO2 hydrogenation to dimethyl ether (DME) via a membrane reactor.•Development of a phenomenological membrane reactor model for DME synthesis.•Sweep gas fed in cocurrent mode to ...promote water and heat removal.•Effect of the membrane properties on the reactor performance.•High sweep gas flow rates promote the removal of water, enhancing DME synthesis.
The direct hydrogenation of CO2 to dimethyl ether (DME) is a promising technology for CO2 valorisation. In this work, a 1D phenomenological reactor model is developed to evaluate and optimize the performance of a membrane reactor for this conversion, otherwise limited by thermodynamic equilibrium and temperature gradients. The co-current circulation of a sweep gas stream through the permeation zone promotes both water and heat removal from the reaction zone, thus increasing overall DME yield (from 44% to 64%). The membrane properties in terms of water permeability (i.e., 4·10−7 mol·Pa−1m−2s−1) and selectivity (i.e., 50 towards H2, 30 towards CO2 and CO, 10 towards methanol), for optimal reactor performance have been determined considering, for the first time, non-ideal separation and non-isothermal operation. Thus, this work sheds light into suitable membrane materials for this applications. Then, the non-isothermal performance of the membrane reactor was analysed as a function of the process parameters (i.e., the sweep gas to feed flow ratio, the gradient of total pressure across the membrane, the inlet temperature to the reaction and permeation zone and the feed composition). Owing to its ability to remove 96% of the water produced in this reaction, the proposed membrane reactor outperforms a conventional packed bed for the same application (i.e., with 36% and 46% improvement in CO2 conversion and DME yield, respectively). The results of this work demonstrate the potential of the membrane reactor to make the CO2 conversion to DME a feasible process.
Summary Background Cardiorespiratory failure is the leading cause of death in Duchenne muscular dystrophy. Based on preclinical and phase 2 evidence, we assessed the efficacy and safety of idebenone ...in young patients with Duchenne muscular dystrophy who were not taking concomitant glucocorticoids. Methods In a multicentre phase 3 trial in Belgium, Germany, the Netherlands, Switzerland, France, Sweden, Austria, Italy, Spain, and the USA, patients (age 10–18 years old) with Duchenne muscular dystrophy were randomly assigned in a one-to-one ratio with a central interactive web response system with a permuted block design with four patients per block to receive idebenone (300 mg three times a day) or matching placebo orally for 52 weeks. Study personnel and patients were masked to treatment assignment. The primary endpoint was change in peak expiratory flow (PEF) as percentage predicted (PEF%p) from baseline to week 52, measured with spirometry. Analysis was by intention to treat (ITT) and a modified ITT (mITT), which was prospectively defined to exclude patients with at least 20% difference in the yearly change in PEF%p, measured with hospital-based and weekly home-based spirometry. This study is registered with ClinicalTrials.gov , number NCT01027884. Findings 31 patients in the idebenone group and 33 in the placebo group comprised the ITT population, and 30 and 27 comprised the mITT population. Idebenone significantly attenuated the fall in PEF%p from baseline to week 52 in the mITT (−3·05%p 95% CI −7·08 to 0·97, p=0·134, vs placebo −9·01%p –13·18 to −4·84, p=0·0001; difference 5·96%p 0·16 to 11·76, p=0·044) and ITT populations (−2·57%p –6·68 to 1·54, p=0·215, vs −8·84%p –12·73 to −4·95, p<0·0001; difference 6·27%p 0·61 to 11·93, p=0·031). Idebenone also had a significant effect on PEF (L/min), weekly home-based PEF, FVC, and FEV1 . The effect of idebenone on respiratory function outcomes was similar between patients with previous corticosteroid use and steroid-naive patients. Treatment with idebenone was safe and well tolerated with adverse event rates were similar in both groups. Nasopharyngitis and headache were the most common adverse events (idebenone, eight 25% and six 19% of 32 patients; placebo, nine 26% and seven 21% of 34 patients). Transient and mild diarrhoea was more common in the idebenone group than in the placebo group (eight 25% vs four 12% patients). Interpretation Idebenone reduced the loss of respiratory function and represents a new treatment option for patients with Duchenne muscular dystrophy. Funding Santhera Pharmaceuticals.
Microreactors present innovative solutions for problems pertaining to conventional reactors and therefore have seen successful application in several industrial processes. Yet, its application in ...heterogeneously catalyzed gas–liquid reactions has been challenging, mainly due to the lack of an easy and flexible methodology for catalyst incorporation inside these reactors. Herein, we report a facile technique for obtaining small (<2 nm) and well-distributed catalytic nanoparticles on the walls of silica-coated capillaries, that act as micro(channel) reactors. These particles are formed in situ on the reactor walls using polyelectrolyte multilayers (PEMs), built by layer-by-layer self-assembly. Manipulating the PEMs’ synthesis condition gives easy control over metal loading, without compromising on particle size. Both monometallic (Au and Pd) and bimetallic (AuPd) nanoparticles were successfully obtained using this technique. Finally, these catalytic microreactors were found to exhibit exceptional activity for the direct synthesis of hydrogen peroxide from H2 and O2.
Abstract
The propagation of particles accelerated at supernova remnant shocks and escaping the parent remnants is likely to proceed in a strongly non-linear regime, due to the efficient ...self-generation of Alfvén waves excited through streaming instability near the sources. Depending on the amount of neutral hydrogen present in the regions around the sites of supernova explosions, cosmic rays may accumulate an appreciable grammage in the same regions and get self-confined for non-negligible times, which in turn results in an enhanced rate of production of secondaries. Here we calculate the contribution to the diffuse gamma-ray background due to the overlap along lines of sight of several of these extended haloes as due to pion production induced by self-confined cosmic rays. We find that if the density of neutrals is low, the haloes can account for a substantial fraction of the diffuse emission observed by Fermi-Large Area Telescope (LAT), depending on the orientation of the line of sight with respect to the direction of the Galactic Centre.
•Effect of vapor-liquid equilibria (VLE) during Fischer-Tropsch Synthesis on the product selectivity and reactor performance.•1-D reactor model taking into account the VLE and the local variation of ...the chain growth probability.•Simplified VLE model offers an attractive alternative to the complete model.•The VLE has significant influence on the hydrodynamics (liquid holdup and pressure drop).•The catalyst efficiency is strongly affected by the liquid composition.
This work analyzes the effect of the vapor-liquid equilibria (VLE) on the productivity and the reactor performance during the Fischer-Tropsch Synthesis (FTS). A reactor model is developed considering the VLE and the local variation of the chain growth probability with temperature and the H2/CO ratio. The model describes the VLE with four different levels of complexity to assess the error introduced by making certain model simplifications. The results show that a simplified VLE model that only accounts for the VLE of CO and H2 offers an attractive alternative since it presents a good accuracy while saving computational time and efforts. Additionally, this work shows that the VLE significantly influences the liquid holdup and the pressure drop. Likewise, the catalyst efficiency is strongly affected by the liquid concentration, and therefore by the VLE. Thus, a full VLE description of reactants and products is needed for the accurate modeling of the FTS reactor.
Amplified neuroinflammatory responses following an immune challenge occur with normal aging and can elicit or exacerbate neuropathology. The mechanisms mediating this sensitized or "primed" immune ...response in the aged brain are not fully understood. The alarmin high mobility group box 1 (HMGB1) can be released under chronic pathological conditions and initiate inflammatory cascades. This led us to investigate whether HMGB1 regulates age-related priming of the neuroinflammatory response. Here, we show that HMGB1 protein and mRNA were elevated in the hippocampus of unmanipulated aged rats (24-month-old F344XBN rats). Furthermore, aged rats had increased HMGB1 in the CSF, suggesting increased HMGB1 release. We demonstrate that blocking HMGB1 signaling with an intracisterna magna (ICM) injection of the competitive antagonist to HMGB1, Box-A, downregulates basal expression of several inflammatory pathway genes in the hippocampus of aged rats. This indicates that blocking the actions of HMGB1 might reduce age-associated inflammatory priming. To test this hypothesis, we evaluated whether HMGB1 antagonism blocks the protracted neuroinflammatory and sickness response to peripheral Escherichia coli (E. coli) infection in aged rats. ICM pretreatment of aged rats with Box-A 24 h before E. coli infection prevented the extended hippocampal cytokine response and associated cognitive and affective behavioral changes. ICM pretreatment with Box-A also inhibited aging-induced potentiation of the microglial proinflammatory response to lipopolysaccharide ex vivo Together, these results suggest that HMGB1 mediates neuroinflammatory priming in the aged brain. Blocking the actions of HMGB1 appears to "desensitize" aged microglia to an immune challenge, thereby preventing exaggerated behavioral and neuroinflammatory responses following infection.
The world's population is aging, highlighting a need to develop treatments that promote quality of life in aged individuals. Normal aging is associated with precipitous drops in cognition, typically following events that induce peripheral inflammation (e.g., infection, surgery, heart attack). Peripheral immune stimuli cause exaggerated immune responses in the aged brain, which likely underlie these behavioral deficits. Here, we investigated whether the alarmin high mobility group box 1 (HMGB1) mediates age-associated "priming" of the neuroinflammatory response. HMGB1 is elevated in aged rodent brain and CSF. Blocking HMGB1 signaling downregulated expression of inflammatory pathway genes in aged rat brain. Further, HMGB1 antagonism prevented prolonged infection-induced neuroinflammatory and sickness responses in aged rats. Overall, blocking HMGB1 "desensitized" microglia in the aged brain, thereby preventing pathological infection-elicited neuroinflammatory responses.
Display omitted
•Shift from sulfuric acid catalysts to novel solid acid foam catalyst for the continuous synthesis of furfural•Solid acid foams as catalyst and liquid-liquid contactor for synthesis ...and in-situ extraction of furfural: high yield, minimal residence time, and stable performance.•Novel and reproducible procedure to deposit stable sulfonic resins on foam structure.
This paper demonstrates the use of sulfonated foam structures, acting both as catalyst and liquid-liquid contactor, during the continuous dehydration of xylose to furfural in biphasic media. First, we develop and optimize a coating procedure comprising a two-step polymerization technique (polypropylene and polystyrene-divinylbenzene), followed by swelling and sulfonation. The method was highly reproducible and led to a stable, well-adhered, 12–50 μm layer of sulfonic resin with an ion exchange capacity of 0.1 meq/cmfoam3. The catalytic foams showed the same activity than H2SO4 in terms of conversion and selectivity versus residence time and temperature. The enhanced mass transfer properties of the foam-based reactor facilitated rapid furfural extraction, thus allowing for higher temperature operations (ca. 20–50 °C higher) and shorter residence times (ca. 10 min vs. 4–5 h) than conventionally reported in the literature, while preserving high furfural selectivity (ca. 70–80%). Finally, the stability of the sulfonated foam catalyst during operation was demonstrated up to 170 °C, although higher temperatures led to a visible decay in activity. We conclude that the sulfonated foams show great potential for this application.
Abstract
Cosmic rays (CRs) govern the energetics of present-day galaxies and might have also played a pivotal role during the Epoch of Reionization. In particular, energy deposition by low-energy (E ...≲ 10 MeV) CRs, accelerated by the first supernovae, might have heated and ionized the neutral intergalactic medium (IGM) well before (z ≈ 20) it was reionized, significantly adding to the similar effect by X-rays or dark matter annihilations. Using a simple, but physically motivated reionization model, and a thorough implementation of CR energy losses, we show that CRs contribute negligibly to IGM ionization, but heat it substantially, raising its temperature by ΔT = 10–200 K by z = 10, depending on the CR injection spectrum. Whether this IGM pre-heating is uniform or clustered around the first galaxies depends on CR diffusion, which, in turn, is governed by the efficiency of self-confinement due to plasma streaming instabilities that we discuss in detail. This aspect is crucial to interpret future H i 21-cm observations, which can be used to gain unique information on the strength and structure of early intergalactic magnetic fields, and the efficiency of CR acceleration by the first supernovae.
Manganese‐based layered oxides are currently of significant interest as cathode materials for sodium‐ion batteries due to their low toxicity and high specific capacity. However, the practical ...applications are impeded by sluggish intrinsic Na+ migration and poor structure stability as a result of Jahn–Teller distortion and complicated phase transition. In this study, a high‐entropy strategy is proposed to enhance the high‐voltage capacity and cycling stability. The designed P2‐Na0.67Mn0.6Cu0.08Ni0.09Fe0.18Ti0.05O2 achieves a deeply desodiation and delivers charging capacity of 158.1 mAh g−1 corresponding to 0.61 Na with a high initial Coulombic efficiency of 98.2 %. The charge compensation is attributed to the cationic and anionic redox reactions conjunctively. Moreover, the crystal structure is effectively stabilized, leading to a slight variation of lattice parameters. This research carries implications for the expedited development of low‐cost, high‐energy‐density cathode materials for sodium‐ion batteries.
A high‐entropy strategy is applied to design a new P2 phase cathode material for sodium‐ion batteries, aiming to improve stability in deeply desodiated states. This material exhibits superior reversibility with 0.61 Na extracted, attributed to triggered lattice‐oxygen redox reaction activity and facilitated Na+ migration. As a result, it demonstrates excellent initial Coulombic efficiency, high energy density, and lengthened cycling performance.
The development of reliable and safe high‐energy‐density lithium‐ion batteries is hindered by the structural instability of cathode materials during cycling, arising as a result of detrimental phase ...transformations occurring at high operating voltages alongside the loss of active materials induced by transition metal dissolution. Originating from the fundamental structure/function relation of battery materials, the authors purposefully perform crystallographic‐site‐specific structural engineering on electrode material structure, using the high‐voltage LiNi0.5Mn1.5O4 (LNMO) cathode as a representative, which directly addresses the root source of structural instability of the Fd3¯m structure. By employing Sb as a dopant to modify the specific issue‐involved 16c and 16d sites simultaneously, the authors successfully transform the detrimental two‐phase reaction occurring at high‐voltage into a preferential solid‐solution reaction and significantly suppress the loss of Mn from the LNMO structure. The modified LNMO material delivers an impressive 99% of its theoretical specific capacity at 1 C, and maintains 87.6% and 72.4% of initial capacity after 1500 and 3000 cycles, respectively. The issue‐tracing site‐specific structural tailoring demonstrated for this material will facilitate the rapid development of high‐energy‐density materials for lithium‐ion batteries.
Crystallographic‐site‐specific structural engineering is performed on the cathode material structure for lithium‐ion batteries, aiming at the root causes of the instability based on the fundamental structure/function relationship. The high‐voltage spinel LiNi0.5Mn1.5O4 (LNMO) cathode with Fd3¯m space group symmetry is employed as a representative, of which two issue‐involved crystallographic sites are directly and simultaneously addressed, contributing to an extraordinarily excellent battery performance.
PDF
