Partial Reactions Research Articles

Catalytic membrane micro-reactor with nano Cu/ZIF-8 assembly in membrane pores by flowing synthesis combining partial ion-exchange

A catalytic membrane micro-reactor (CMMR) is fabricated, with nano Cu/ZIF-8 particles immobilized in the pores of the microfiltration membrane for flow-through catalysis. Nano ZIF-8 is firstly assembled in polyethersulfone (PES) membrane pores by flowing synthesis and then Cu nanoparticles (NPs) are synthesized in-situ in ZIF-8 by the partial ion-exchange reaction. Cu/ZIF-8 nanoparticles are distributed evenly throughout the whole direction of membrane thickness while Cu NPs are dispersed well in ZIF-8. The 4-nitrophenol (4-NP) reduction is used to test the performance of the CMMR. The 4-NP reduction rate being 99.3% is achieved when the membrane flux is 2293 L m −2 h −1 . The CMMR has good stability for over 210 min and presents a surprisingly high apparent reaction rate constant ( K app , 837.43 min −1 ) at room temperature with the loading of ZIF-8 being 85 mg g −1 (PES) and Cu loading cycle number being 1. Compared with batch catalysis by powder catalysts, the K app is increased by 4 orders of magnitude via flow-through catalysis mode using CMMR. The nanoscale configuration of ZIF-8 and Cu NPs assembled inside pores of the membrane enhances remarkably the catalytic activity owing to the enhanced contact and mass transfer in the confined space of membrane pores. A catalytic membrane micro-reactor (CMMR) with nano Cu/ZIF-8 immobilizing in membrane pores was fabricated by flowing synthesis combining partial ion-exchange. This structure provides excellent activities due to the synergistic effect of membrane pores, ZIF-8, and nano Cu. Cu/ZIF-8 catalytic membrane micro-reactor fabricated by flowing synthesis method Cu/ZIF-8 assembled throughout membrane thickness with high loading and dispersity Synergistic effect between membrane pores, ZIF-8 and nano Cu enhances 4-NP reduction Reduction rate of 4-NP over 99.3% achieved with stability over 210 min Apparent reaction rate constant improved by 4 orders of magnitude via flow-through catalysis

Altering the binding determinant on the interdigitating loop of mandelate racemase shifts specificity towards that of d-tartrate dehydratase

The enolase superfamily (ENS) has served as a paradigm for understanding how enzymes that share a conserved structure, as well as a common partial reaction (i.e., metal-assisted, Brønsted base-catalyzed enol(ate) formation), evolved from a common progenitor to catalyze mechanistically diverse reactions. Enzymes of the mandelate racemase (MR)-subgroup of the ENS share interdigitating loops between adjacent, 2-fold symmetry-related protomers of the tightly associated homodimers that comprise their quaternary structures. For the MR-subgroup members MR and d-tartrate dehydratase (TarD), the tip of the loop contributes a binding determinant to the adjacent active site (i.e., Leu 93 and Lys 102, respectively). To assess the role of Leu 93 of MR in substrate specificity and catalysis, we constructed L93 variants bearing hydrophobic (L93A, L93F, and L93W), polar neutral (L93N), acidic (L93D), or basic (L93K and L93R) residues at position 93. Gel filtration-HPLC revealed that wild-type MR and all L93 MR variants, apart from L93R MR (dimeric), were tetrameric in solution. The catalytic efficiency (kcat/Km) was reduced in the R→S and S→R reaction directions for all variants, primarily due to reduced turnover (kcat). Substitution of Leu 93 by Lys or Arg to mimic Lys 102 of TarD enhanced the binding of malate and tartrate, with meso- and d-tartrate exhibiting linear mixed-type inhibition of L93K MR. Despite the striking 500-fold increase in the binding affinity of d-tartrate, relative to (S)-mandelate, L93K MR exhibited no TarD activity. MD simulations suggested that the failure of L93K MR to catalyze α-deprotonation (i.e., H-D exchange) arises from inappropriate positioning of the Brønsted base (Lys 166). Thus, a change in binding determinant on the interdigitating loop can play a significant role in governing substrate specificity within the ENS, but does not necessarily confer ‘new’ catalytic activity despite similarities in catalytic machinery.

Molten salt gasification characteristics of various organic waste fuels for HF-DCFC

With fossil fuel prices soaring due to the Ukraine crisis, countries must not only achieve energy self-sufficiency in the future, but also curb CO2 emissions to prevent global warming. In order to achieve both of these goals, our laboratory has been developing a High Functional Direct Carbon Fuel Cell (HF-DCFC) composed of a molten salt gasification and a Tubular Molten Carbonate Fuel Cell. HF-DCFC can generate electricity directly using various organic wastes as fuel, but the previous study was elucidated that its cell performance is greatly affected by the fuel type. In this study, the gasification characteristics of polyethylene (PE), wood pellets (WP), and onion peels (ONION) were investigated for the installation of HF-DCFCs in each community as a waste treatment generator. As a result, the highest CO and H2 production as fuel for HF-DCFC occurred with WP under 70(25CO2/75N2)/30H2O atmosphere. PE produced hardly CO and H2 productions, but high sulfide emissions. ONION gasification produces CO and H2 second only to WP with little CH4 production, but gasification characteristics were greatly enhanced when ONION was wrapped in PE and fed. Moreover, in all fuels, the addition of air inhibits the formation of fuel gas through partial oxidation reactions and reduces gasification efficiency but increases energy efficiency because the oxidation reactions raise the temperature of the molten salt.

A multi-technique approach to unveil the redox behaviour and potentiality of homoleptic CuI complexes based on substituted bipyridine ligands in oxygenation reactions.

The effect of differently substituted 2,2'-bipyridine ligands (i.e. 6,6'-dimethyl-2,2'-bipyridine, 5,5'-dimethyl-2,2'-bipyridine, 6,6'-dimethoxy-2,2'-bipyridine and 2,2'-bipyridine) on the reversible oxidation of the resulting CuI homoleptic complexes is investigated by means of a multi-technique approach (electronic and vibrational spectroscopies, DFT, electrochemistry). Among the four tested complexes, [CuI(6,6'-dimethyl-2,2'-bipyridine)2] (PF6) shows a peculiar behavior when oxidized with an organic peroxide (i.e. tert-butyl hydroperoxide, tBuOOH). The simultaneous use of UV-Vis-NIR and Raman spectroscopy methods and cyclovoltammetry, supported by DFT based calculations, allowed identifying (i) the change in the oxidation state of the copper ion and (ii) some peculiar modification in the local structure of the metal leading to the formation of a [CuIIOH]+ species. The latter, being able to oxidize a model molecule (i.e. cyclohexene) and showing the restoration of the original CuI complex and the formation of cyclohexanone, confirms the potential of these simple homoleptic CuI complexes as model catalysts for partial oxygenation reactions.

Update on dermatophytosis in Mashhad, Northeastern Iran, emergence of infection with Trichophyton persicum.

Background:Dermatophytosis is a common global superficial mycosis caused by a group of keratinophilic moulds known as dermatophytes that invade the skin and keratinized tissues such as hair and nails of humans and animals. This study takes identification of a collection of clinical dermatophyte isolates by using partial sequencing of translation elongation factor-1α (Tef-1α) gene aiming both to update the epidemiological status of dermatophytosis in Mashhad, Northeastern Iran and to corroborate the efficacy of Tef-1α for species-level identification of dermatophytes.Method:The demographic data related to 87 culture-positive dermatophytes isolated from patients clinically suspected to have dermatophytosis were collected. The dermatophyte isolates were subjected to a partial polymerase chain reaction (PCR)-sequencing of Tef-1α gene by using specific pan-dermatophyte primers. The data were analysed by SeqMan software, the sequences were compared and aligned with the GenBank database and the isolates were identified.Results:Identification based on Tef-1α partial sequence was successful for all isolates. The identified dermatophyte isolates in decreasing order were as Trichophyton interdigitale 19 (22%), T. tonsurans 19 (22%), T. mentagrophytes 13 (15%), T. persicum 10 (11.5%), Epidermophyton floccosum 9 (10.3%), Microsporum canis 7 (8%), T. rubrum 5 (5.7%), T. violaceum 2 (2.2%), Nannizzia fulva 2 (2.2%) and N. persicolor 1 (1.1%). The isolates have been associated with clinical forms of tinea corporis (n = 38; 43.7%), tinea faciei (n = 13; 15%), tinea cruris (n = 12; 13.9%), tinea manuum (n = 7; 8%), tinea unguium (n = 7; 8%), tinea capitis (n = 7; 8%) and tinea pedis (n = 3; 3.4%).Conclusion:Dermatophytosis has yet remained a public health problem in Northeastern Iran, and infection with new and less frequent species, e.g., T. persicum, N. fulva and N. persicolor have emerged. The Tef-1α gene partial sequencing reconfirmed the resolution power of this locus for the determination of species boundaries in dermatophytes.

Similarity Deviation of Diameter and Thickness Effects

One way to characterize the similarity of detonations (in the sense of their reaction rate) is through size effect tests. Using cylinders (rods), they’re called diameter effect tests, and using slabs, they’re called thickness effect tests. From the steady state equations of motion of these configurations it follows that they scale as r(D)=h(D), where r=rod radius, h=slab thickness, and D=steady detonation velocity. But tests show deviations from such scaling. Here we propose an explanation to these deviations. The explanation is based on a previous work in which we show that a boundary layer of partial reaction usually forms when a detonation wave is grazing along a free boundary. We suggest and show via computer simulations that those scaling deviations are related to this partially reacted boundary layer effect.

Combustion and emission characteristics of natural gas engine with partial-catalytic oxidation of the fuel

Combustion, emission characteristics and the economic performance of a heavy-duty natural gas engine blended with different ratios of reformed gas were investigated, and the feasibility of applying the fuel partial oxidation catalytic reforming system on a heavy-duty natural gas engine was discussed. Experimental results showed that the use of Rh/γ-Al2O3 as a catalyst of partial oxidation reaction of natural gas fuel requires low initial reaction inlet gas temperature, and it has good catalytic performance and durability, which makes it feasible to be applied on vehicles. Blending with reformed gas from partial oxidation reaction significantly reduces NOX and CH4 emission and effectively reduces coefficient of variance of peak pressure. In additions, no significant change in fuel consumption was observed after blending with reformed gas, while CO emissions increased. In general, the combination of on-board fuel partial oxidation catalytic reforming system to improve the performance of natural gas engines has good prospects.

Blackened calcium‐based composite particles and their apparent kinetics features for solar thermochemical energy storage

AbstractThe calcium looping (CaL) thermochemical thermal energy storage is one of the best high‐temperature heat storage schemes for 3th concentrating solar power (CSP) photothermal power. However, the application of this technology is greatly hindered by the low solar absorption capability and the poor cyclic stability of CaCO3/CaO‐based material. In this article, the solar absorbing capability of CaCO3 particles is enhanced by doping Mn‐Fe oxides, meanwhile, awns of setaria faberis (ASF) and microcrystalline cellulose (MCC) are used as bio‐templates to generate pores inside the particles. The pore‐making process promotes the cyclic stability and carbonation kinetic features of the composite particles simultaneously. The test results show that the proposed particles possess adequate anti‐crushing strength, high cyclic stability, high solar absorption, and high carbonation rate. In addition, the apparent carbonation kinetic features of the composite porous particles are studied with the influencing factors such as CO2 partial pressure, reaction temperature, and particle morphology taken into consideration. A kinetic equation involving these parameters is developed with the thermogravimetry data of the prepared samples. By employing this kinetic function, the carbonation reaction of the prepared particles inside the carbonator becomes predictable, which is of great significance for the design and regulation of the carbonator achieving highly stable thermal output from the CaL thermochemical heat storage system.

Charge-discharge properties and reaction mechanism of cation-disordered rutile-type Li1.2MnFe1.2F6.8

A carbon-coated Li1.2MnFe1.2F6.8 with a cation-disordered rutile structure is presented for the first time as a positive electrode material for lithium-ion batteries. For improved performance, the composite electrode is investigated at 90 °C using a thermally stable ionic liquid electrolyte. A combination of synchrotron X-ray diffraction, X-ray photoelectron spectroscopy and half-cell tests establish that the reversible extraction/insertion of lithium from/into Li1.2MnFe1.2F6.8 in the 2.5–4.5 V voltage range at 90 °C involves Fe(III)/Fe(II) and Mn(III)/Mn(II) redox reactions alongside partial conversion reactions between the rutile Li1.2MnFe1.2F6.8 and a mixture of LiF and rutile FeF2. Deep discharge to 2.0 V involves a conversion reaction to LiF and metallic Fe and Mn accompanied by the partial preservation of the rutile structure.

Modelling of Refuse-Derived Fuel Gasification Reactor

Landfilled municipal solid waste (MSW) emits significant quantities of greenhouse gases (GHG). The gasification process can reduce not only the amount of deposited waste, but also the amount of methane (CH4) emitted by landfills. With development of gasification processes, it is possible to chemically convert the waste into useful products, synthesis gas. This energy carrier can be used to generate electricity and produce other valuable materials such as hydrogen, methanol, etc. The raw material of gasification technology is the refused-derived fuel (RDF), which is the non-recyclable part of the MSW. Pyrolytic, oxidation and reduction processes can be separated in the downdraft moving bed reactor type.The aim of this work is to study the model and the reactions of the pyrolysis and oxidation zone and to investigate whether the model of oxidation zone can be integrated into the model of pyrolysis zone to reduce the computational capacity requirements. RDF pellet sample was milled, and representative samples were studied by thermogravimetric (TG). The kinetic parameters of the reactions were identified. The applied kinetic model can be used to calculate the mass of the produced gas, and a model suitable for determining the gas composition was added. The gas composition was estimated based on the mass balance of the elements. In the first approach, the composition and amount of gas obtained during the simulation of the pyrolysis zone was the raw material of the oxidation zone, then the composition of gas was calculated based on partial oxidation reactions. In the other approach, the gas composition was determined in one step. Both methods provided close to identical composition while the time of computation was almost the same. The biggest relative error in mass balance of the elements was 11.19 % in case of Approach 1 and it was less than 3 % in case of Approach 2.

Comparison and optimization of different fuel processing options for biogas-fed solid-oxide fuel cell plants

The biogas needs to be reformed before electro-chemical conversion in the solid-oxide fuel cell, which can be promoted efficiently with wise thermal management and reforming conditions. To ensure the system safety and catalysts durability, additional mineral-bearing water and carbon deposition should be avoided. This paper conducted a detailed biogas-SOFC CHP system analysis considering four layouts, featuring hot and cold recirculation of the anode off-gas, partial oxidation and complete internal reforming. The process optimization and sensitivity analysis are performed with the design variables including the recirculation ratio, and external reformer temperature. The anode supported SOFC operates at 800 °C and 0.4 A/cm2 current density. The results show that pre-reforming with hot recirculation and cold recirculation schemes achieve the highest system efficiency between 56% and 63%. The pre-reforming with hot recirculation scheme has a broader self-sufficient water range eliminating the carbon deposition risk at the recirculation ratio of 42–78% and reforming temperature of 400–650 °C. The no pre-reforming with hot recirculation scheme achieves maximum system efficiency of 58% due to the fuel dilution. Moreover, the partial oxidation with hot recirculation scheme maximum efficiency is limited to 58.9%, given that the partial oxidation reaction is less efficient than steam and dry reforming reactions. The proposed system layout could demonstrate the feasibility of biogas-SOFC with different reforming options especially on small scale with high efficiency and optimal thermal integration opportunities.

Measuring Diffusion Coefficients of the Ceria Phase in a Dual-Phase Oxygen Permeation Membrane Using a Combined Polarization - Kelvin Probe Force Microscopy Method

Dual-phase membranes with FeCo2O4 or its iron-rich pendant Fe2CoO4 and Gd-doped ceria as an oxygen ion conductor have already been successfully applied as oxygen permeation membranes with high permeability in the temperature range above 800 °C [1-3]. Apart from Gd-doped ceria, Sm-doped ceria also can be an interesting alternative in this kind of composite due to its high ionic conductivity [4].As especially ceria or ceria-based composites have gained more and more interest for low-temperature applications, e.g. as catalyst materials, current research efforts are aiming to improve the composition and microstructure of such dual-phase membranes for application in a membrane reactor at considerably lower temperatures (below 600 °C) to perform partial oxidation reactions. For temperatures between 600-1200 °C the defect chemistry of these materials is well established, but experimental data for low temperature charge transport are limited and not fully understood, yet.Kelvin Probe Force Microscopy (KPFM) is an Atomic Force Microscopy (AFM)-based measurement method which can measure the local surface potential (or from the physics view: the Volta potential) of the sample [5, 6]. The surface potential is a measure for local changes of the defect chemistry, as it is directly related to the local Fermi niveau [7]. The implications of local oxidation and reduction at low temperatures for charge carrier mobility in pure ceria, and especially in dual-phase materials, are not very well understood so far, but KPFM can be used to measure the surface potential difference directly at the polarized contact area as well as to map the time-dependent relaxation process of the introduced gradient, also giving information about the local surface potential distribution, lateral extent of the gradient, variations of the shape of the gradient etc. [8, 9].In the present study, single ceria grains in a dual-phase Ce0.8Sm0.2O2-δ + FeCo2O4 oxygen permeation membrane were polarized at room temperature in ambient air using a Pt-coated AFM tip and a large silver paste back contact. Subsequently, the introduced defect concentration gradient (which is visible as a gradient of the surface potential) and the relaxation process over time was monitored by KPFM.By comparing the measurement results to previously acquired data of single phase ceria samples with different doping concentrations and crystallinity, we were able to show that by this technique, chemical diffusion coefficients of a single phase in a composite material are accessible. Acknowledgements: The work was funded by the German Research Foundation - project #387282673. Literature: Ramasamy, M.; Baumann, S.; Palisaitis, J.; Schulze‐Küppers, F.; Balaguer, M.; Kim, D.; Meulenberg, W. A.; Mayer, J.; Bhave, R.; Guillon, O. J Amer Ceram Soc 2016, 99 (1), 349-355.Ramasamy, M.; Persoon, E. S.; Baumann, S.; Schroeder, M.; Schulze-Küppers, F.; Görtz, D.; Bhave, R.; Bram, M.; Meulenberg, W. A. Journal of membrane science 2017, 544, 278-286.Lin, Y.; Fang, S.; Su, D.; Brinkman, K. S.; Chen, F. Nature Comm 2015, 6 (1), 1-9.Mori, T.; Drennan, J.; Lee, J.-H.; Li, J.-G.; Ikegami, T. Solid State Ionics 2002, 154-155, 461-466.Örnek, C.; Leygraf, C.; Pan, J. Corr Eng Sci Tech 2019, 54 (3), 185-198.Melitz, W.; Shen, J.; Kummel, A. C.; Lee, S. Surf Sci Rep 2011, 66 (1), 1-27.Zhang, Z.; Yates, J. T. Chem Rev 2012, 112 (10), 5520-5551.Neuhaus, K.; Schulze-Küppers, F.; Baumann, S.; Ulbrich, G.; Lerch, M.; Wiemhöfer, H.-D. Solid State Ionics 2016, 288, 325-330.Lee, W.; Lee, M.; Kim, Y.-B.; Prinz, F. B. Nanotechnology 2009, 20 (44), 445706.

The Role of Pretreatment 18F-FDG PET/CT for Early Prediction of Neoadjuvant Chemotherapy Response in Patients with Locoregionally Advanced Nasopharyngeal Carcinoma

IntroductionTo evaluate the role of maximal standardized uptake values (SUVmax) and total lesion glycolysis (TLG) from serial 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for early prediction of neoadjuvant chemotherapy (NAC) response in locoregionally advanced nasopharyngeal carcinoma (LANPC).MethodsA total of 121 LANPC patients who completed pretreatment 18F-FDG PET/CT between June 2017 and July 2020 were retrospectively included. The median age of all the participants was 50 years old (range: 19–74 years), with 94 (77.7%) males and 27 (22.3%) females. The SUVmax from the primary tumor site (SUVmax-PT) and the total lesion glycolysis from the primary tumor site (TLG-PT) were recorded. Tumor response was calculated according to the Response Evaluation Criteria in Solid Tumor (RECIST) 1.1 Criteria at two-week post-secondary NAC cycle. Patients who achieved an objectively partial or full reaction after two cycles of NAC were defined as ‘responders’, and patients who obtained stability or progression were classified as ‘non-responders’.ResultsAfter two cycles of NAC, 96 patients were categorized as “responders” and 25 patients as “non-responders”. The optimal thresholds of the SUVmax-PT were 11.8 and 38.5 for the TLG-PT. Non-responders were significantly associated with high SUVmax-PT (HR, 3.49; 95% CI, 1.17–10.36; p = 0.024) and TLG-PT (HR, 4.45; 95% CI, 1.44–13.78; p = 0.010) in multivariate analysis. Recursive partitioning analysis (RPA) categorized patients into three prognostic groups based on SUVmax-PT and TLG-PT: high-response group, intermediate-response group, and low-response group, with corresponding favorable response rates of 94%, 80%, and 55%, respectively. Moreover, a nomogram was created based on metabolic parameters that precisely projected an individual’s response of NAC (C-index, 0.787; 95% CI, 0.533–1.000).ConclusionPretreatment 18F-FDG PET/CT to measure SUVmax-PT and TLG-PT could be a useful non-invasive method for early indication of NAC efficacy. The nomogram based on PET/CT parameters may potentially provide direction for treatment decisions based on NAC levels.

Photochemical study of interaction of chromium (III) with EDTA reaction kinetics: a chemical kinetics laboratory experiment

Abstract: The kinetics of the complex ion of chromium (III) with EDTA formation reaction in a water solution was studied. The possibility of simultaneous determination of partial reaction orders with respect to all reactants was shown. The influence of temperature and hydrocarbonate-ions as a catalyst on the reaction rate was studied. It was shown that this reaction is very suitable for the experimental demonstration of formal kinetics regularities and can be used in a university laboratory practice course. The methodical instructions for students were developed.

Kinetics of the low-pressure chemical vapor deposited tungsten nitride process using tungsten hexafluoride and ammonia precursors

Tungsten nitride (WNx) is a hard refractory material with low electrical resistance that can be deposited using multiple methods. This study focuses on the microstructrual development of low pressure chemical vapor deposition grown WNx coatings. Also, the growth kinetics is studied and discussed in terms of the resulting microstructures. Samples of WNx were deposited using WF6, NH3, and Ar at 592–887 K in a hot-wall reactor with variable gas mixture compositions (NH3:WF6 = 0.5–25). The coatings were nitrogen-rich (x ∼ 1.65) and oxygen-free as determined by time-of-flight-elastic recoil detection analysis. X-ray diffraction showed that the coatings transformed from being amorphous to crystallizing as β-W2N at 641–690 K. The morphologies changed with deposition temperature. Being very fine grained and nodular at deposition temperatures 740 K and below, increasing the deposition temperature to 789 K while employing a NH3:WF6 molar ratio of 1, large disc-shaped protrusions were formed. When increasing the NH3:WF6 molar ratio to 25, striped facets became increasingly dominant. Investigating the latter by transmission electron microscopy, a microstructure of smaller ridges formed by twinning, oriented as <211> in the out-of-plane direction, was revealed across the facet surfaces. Transmission Kikuchi diffraction confirmed that <211> was the texture of these coatings. The partial reaction order of WF6 and NH3 at 740 K was determined to be close to 1/6 and 1/2, respectively. The apparent activation energy ranged from 82 to 12 kJ/mol corresponding to deposition temperatures from 592 to 887 K.

Cultivation of sulfide-driven partial denitrification granules for efficient nitrite generation from nitrate-sulfide-laden wastewater

Sulfide partial denitrification (SPD) is an alternative pathway for nitrite production accompanied with elemental sulfur (S0) production for nitrate removal from wastewater with anammox. In this study, the SPD granular sludge was cultivated for the first time in an upflow anaerobic sludge bed (UASB) reactor to reach the efficacy of maximum nitrate-to-nitrite transformation ratio of 92% and an in-situ maximum NO3−-N reduction rate of 2.46 kg-N/m3-d, both much higher than literature results. Mature granules had an average particle size of 2.52 mm and hold smooth surface with excess rod bacteria. The elements Ca and S, and proteins in extracellular polymeric substances contributed to granule structure's stability. Enriched Thiobacillus genus was proposed to accumulate nitrite at moderate HRT (2–6 h). The immobilized functional strains assist efficient partial nitrification reactions to be realized with formed S0 as byproduct.

Hierarchical Nanostructured Co-Mo-B/CoMoO4-x Amorphous Composite for the Alkaline Hydrogen Evolution Reaction.

Transition metal borides (TMBs) are a class of important but less well-explored electrocatalytic materials for water splitting. The lack of an advanced methodology to synthesize complex nanostructured TMBs with tunable surface properties is a major obstacle to the exploration of the full potential of TMBs for electrocatalytic applications. Here, we report the facile fabrication of a cobalt foam (CF)-supported hierarchical nanostructured Co-Mo-B/CoMoO4-x composite using a hydrothermal method, followed by annealing and NaBH4 reduction treatments. Our study found that NaBH4 reduction of CoMoO4 resulted in the concurrent formation of amorphous Co-Mo-B and an O-vacancy-rich CoMoO4-x substrate, which cooperatively catalyzed the hydrogen evolution reaction (HER) in an alkaline electrolyte. The hierarchical nanoporous structure derived from the dehydration and partial reduction reactions of the CoMoO4·nH2O precursor could offer ample accessible active sites, as well as interconnected channels for rapid mass transfer. In addition, the in situ growth of electrically conductive Co-Mo-B nanoparticles on the defective structured CoMoO4-x substrate imparted the electrocatalyst with good electrical conductivity. As a result, the Co-Mo-B/CoMoO4-x/CF catalyst showed impressively high activity and outstanding stability for the alkaline HER, outperforming most reported TMB electrocatalysts. For instance, it required an overpotential of 55 mV to afford 10 mA·cm-2 and showed a fluctuation of only ±8 mV in a 100 h constant-current test at 100 mA·cm-2.

Lula and the Future of the Past

Lula and the Future of the Past

Origin of spinel-hosted mineral inclusions in mantle peridotite from Setogawa in the Circum-Izu Massif Serpentine Belt, central Japan: Implications for the chromitite genesis

Plagioclase-impregnated mantle harzburgites from Setogawa area in the Circum-Izu Massif Serpentine Belt (of Miocene in age), central Japan, contain chromian spinel (chromite) grains that have minute globular inclusions composed of micas, amphiboles and pyroxenes. They are similar in texture and chemistry to those in chromitites as well as in some plutonic rocks, such as dunites and troctolites, form the Moho transition zone (MTZ). The Setogawa harzburgite host is similar in petrography and geochemistry to the MTZ harzburgite from the Oman ophiolite, and is possibly a low-pressure restite after melt-assisted partial melting or reaction with a percolating magma. The orthopyroxene-melt reaction, which is essentially responsible for producing those rocks from the peridotite (harzburgite), can precipitate chromian spinel as well as generate chemically heterogeneous melts along decomposing orthopyroxenes. The spinel-hosted melt inclusions in podiform chromitites are most frequently trapped at the reaction front between the spinel-oversaturated, spinel-loaden magma and mantle orthopyroxene (=harzburgite). The spinel-loaden magma had been produced via the same reaction at lower levels and moved upward. The spinel quickly overgrows to include chemically heterogenous melt drops, some of which are high in Cr/Al ratio and precipitate high-Cr spinel via reaction with the wall spinel. The chemical character (Cr/Al ratio) of podiform chromitites would be determined by the accumulative contribution from the melt derived from orthopyroxene decomposition during the passage of the melt through the upper mantle. We can speculate that the chromian spinel grains containing similar melt inclusions from the stratiform chromitite are transported as xenocrysts of mantle origin. The parental magma for layered intrusions possibly reacted with the peridotite when it passed through the mantle before arriving at a crustal magma chamber, showing a possible genetic linkage between the podiform and stratiform chromitites.

Colored cotton wastes valuation through thermal and catalytic reforming of pyrolysis vapors (Py-GC/MS)

This study aims to analyze the products of the catalytic pyrolysis of naturally colored cotton residues, type BRS (seeds from Brazil), called BRS-Verde, BRS-Rubi, BRS-Topázio and BRS-Jade. The energy characterization of biomass was evaluated through ultimate and proximate analysis, higher heating value, cellulose, hemicellulose and lignin content, thermogravimetric analysis and apparent density. Analytical pyrolysis was performed at 500 °C in an analytical pyrolyzer from CDS Analytical connected to a gas chromatograph coupled to the mass spectrometer (GC/MS). The pyrolysis vapors were reformed at 300 and 500 °C through thermal and catalytic cracking with zeolites (ZSM-5 and HZSM-5). It has been noticed that pyrolysis vapor reforming at 500 °C promoted partial deoxygenation and cracking reactions, while the catalytic reforming showed better results for the product deoxygenation. The catalyst reforming of pyrolysis products, especially using HZSM-5 at 500 °C, promoted the formation of monoaromatics such as benzene, toluene, xylene and styrene, which are important precursors of polymers, solvents and biofuels. The main influence on the yields of these aromatic products is due to the catalytic activity of ZSM-5 favored by increased temperature that promotes cracking reactions due expanded zeolites channels.