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The solvent effect on H-BEA catalyzed cyclohexanol dehydration was investigated in water, dioxane, and cyclohexanol. The dynamic evolution of the Brønsted acid site of zeolite and its interaction with reactant molecules in different solvents were explored with ab initio molecular dynamics simulations, providing reliable configuration sampling to obtain configurations at equilibrium. Solvent profoundly changes the adsorption as well as the dehydration reaction of cyclohexanol in H-BEA, where the reaction is determined to follow the E2 mechanism in water and dioxane but the E1 mechanism in cyclohexanol untill saturation uptake. Near saturation uptake, all three solvents significantly reduce the cyclohexanol dehydration rates in H-BEA. Cyclohexanol loading also dramatically affects the kinetics of the dehydration reaction, displaying an overall decreasing trend with a local minimum present at intermediate loading of 6 molecules per unit cell, which is a result of the entropic effect associated with greater freedom of motion of the transition state. Rigorous quantification of enthalpy and entropy contributions to cyclohexanol adsorption and activation shed light on the solvent effect of zeolite-catalyzed alcohol dehydration. [ABSTRACT FROM AUTHOR]

Biomass is the most abundant and renewable resource in the pursuit of bio-value added chemicals. Platinum-group metals and typical nonprecious transition metals are considered as the active metals for catalytic conversion of biomass into value added chemicals and fuels. Rhenium (Re) in particular is a versatile, oxophilic element with a broad variety of easily accessible oxidation states ideally suited for catalytic applications. Taking advantage of Re's unique properties and the green concept of biomass, the catalytic transformation of lignocellulose with Re-based catalysts has gained considerable attention, leading to the preparation of value-added chemicals including olefins through deoxydehydration from the conversion of polyols, aromatics through depolymerization of lignin, and alkane fuels through a hydrodeoxygenation reaction. This review focuses on the catalytic conversion of lignocellulosic main components (cellulose, hemicellulose, and lignin) and their derived platform chemicals into value-added chemicals and fuels over homogeneous and heterogeneous Re-based catalysts. The reaction pathways for biomass conversion over Re-based catalysts are introduced based on different feedstocks or chemical bonds. The unique role of Re species in tailoring the active sites of catalysts for these reactions is summarized and possible reaction mechanisms are discussed. Finally, an outlook is provided to underscore both the challenges and opportunities associated with this interesting and important field, offering a comprehensive overview on the current state of Re catalysis with a low carbon footprint. [ABSTRACT FROM AUTHOR]

Carbon aerogels (CAs) have garnered significant attention due to their multifunctional applications. Biomass waste, abundantly generated by agriculture and industry, serves as a primary carbon source. However, developing a facile, sustainable, and efficient method to produce CAs from biomass waste remains challenging. In this study, a one‐step Zn2+ ion‐glue‐assisted carbonization technique was developed to produce large‐scale, high‐performance CAs. Various biomass materials (wood bits, peanut shells, bamboo bits, and straw waste) were treated in a molten salt system (ZnCl2/KCl) at 300 °C for 2 h to obtain large‐block CAs derived from biomass bits. Zn2+ ions cleave cellulose hydrogen bonds in natural biomass, facilitating the dehydration crosslinking reaction among cellulose, hemicellulose, and lignin, thus reconstructing the entire block structure. The resulting CAs exhibited high porosity (95 %) and low density (0.078 g/cm3). Numerous hydroxyl and carbonyl groups were preserved during the low‐temperature treatment, facilitating chemical modification for diverse applications. For instance, amidoxime functionalized CAs were utilized as filters for selective and highly efficient extraction of U(VI) from wastewater. The adsorption capacity and extraction efficiency reached 801.2 mg/g and 95 % with a flux rate of 6.1×103 L/m2 ⋅ h. [ABSTRACT FROM AUTHOR]

In single‐step conversion of glycerol to propene, the intricate catalytic pathways with molybdenum and niobium catalysts remain elusive. While these catalysts can effectively accelerate the hydrogenolytic cleavage of the glycerol CO bonds, resulting in a high selectivity to propene, the routes have not been thoroughly studied. This study explores the reaction routes and the role hydrogen plays in determining the product distribution. The hydrodeoxygenation (HDO) of glycerol was investigated using various glycerol purities in both batch and continuous reaction modes. Remarkably, Mo(PO4)x and Nb(PO4)x demonstrated catalytic performance with raw glycerol, indicating that impurities had no detrimental effect on the catalyst's activity. In batch mode, a propene selectivity of 53% was achieved over Mo(PO4)x as the catalyst, highlighting the catalyst's stability under these conditions. In continuous operation, the highest product selectivity to propene (12%) was observed at low temperatures (573 K), while more C2 to C6 alkanes were formed at increased temperatures (623 and 673 K). Whereas a hydrogen atmosphere promotes formation of 2‐propenol, as primary precursor to propene, an inert atmosphere leads to increased formation of propanal and dissociation products. Our work has elucidated new routes to upcycle biorenewable glycerol to propene over Mo(PO4)x and Nb(PO4)x catalysts. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization (HTC) is emerging as a promising technology for converting waste biomass into a dense coal-like product known as hydrochar. Oily sludge (OS), known for its toxic, carcinogenic, and mutagenic effects, is classified as hazardous waste, posing negative implications for both humans and the ecosystem if improperly disposed. Consequently, the conversion of hazardous oily sludge into safe and renewable products offers significant benefits. To investigate the HTC process further, a design matrix consisting of 20 experimental runs was utilized, integrating results obtained from HTC experiments as input for response surface methodology (RSM). The variables were restricted to a temperature range of 175°C–250°C, a time span of 0.5–2 h, and a solid load range of 3%–8%. Analyzing the data, it was observed that raw sludge initially exhibited a hydrogen-to-carbon (H/C) ratio of 1.33 and an oxygen-to-carbon (O/C) ratio of 0.59. However, following HTC processing, these ratios decreased significantly to 0.18 (at 250°C, 2 h, 3% solid load) and 0.691 (at 250°C, 1 h, 5.5% solid load), respectively. These decreases can be attributed to dehydration and decarboxylation reactions that occurred during the HTC process. The model equation developed using RSM was: carbon content = 66.29 + 6.98A + 0.3515B–2.60C – 0.0412AB + 0.1730AC – 0.0037BC – 1.83A2 + 0.8005B2 – 0.945C2. Carbon densification increased from 1.09 to 1.45 with hydrochar retaining 66.5%–77.65% of the carbon. HTC holds promise as a sustainable technology for carbon and energy recovery. [ABSTRACT FROM AUTHOR]

Dielectric barrier discharge (DBD) nonthermal plasma is applied for the gasification of kitchen waste. The gas production performance of kitchen waste gasification based on DBD under different reaction ambientes is studied. Density functional theory (DFT) simulations are used to investigate the gas production mechanism via glucose and aspartate. Scanning electron microscopy (SEM) and Raman spectroscopy are used to investigate the physicochemical properties of the produced carbon materials and reveal the plasma reaction mechanism. The plasma treatment of millet and soybean has good gasification effect and can inhibit tar production. N2 and CO2 ambientes are more conducive to the gasification of millet and soybean. The H2 concentration in plasma‐treated millet gasification under plasma in N2 ambient can reach 4%. Glucose is finally decomposed through ring‐opening reaction, decarbonylation reaction, dehydration reaction, and carbon–carbon bond breaking. And the decomposition process of aspartic acid mainly includes decarbonylation and deammonia reaction. With the increase of gas ionization energy, the surface pore structure of the carbon material after plasma treatment is more developed, which indicates that the reaction between plasma and solid is on a layer by layer basis with the solid surface facing the inner surface. This paper aims to provide valuable theoretical support for the application of DBD in the treatment of kitchen waste. [ABSTRACT FROM AUTHOR]

The reliance on wasteful stoichiometric reagents to accomplish dehydration reactions such as esterification, amidation, and alcohol substitution is a longstanding challenge in synthetic chemistry. To address this problem, an electrochemical approach has been developed as a new conceptual platform for dehydration reactions. As a proof-of-concept demonstration, an electrochemical esterification protocol has been described that proceeds at room temperature, without acid or base additives, and without consuming stoichiometric reagents. This approach therefore overcomes key complications of esterification chemistry, and we envision that it will similarly enable improvements to a range of important, related transformations. 1 Introduction 2 An Electrochemical Design for Catalytic Dehydration 3 Electrochemical Esterification 4 Conclusions [ABSTRACT FROM AUTHOR]

Introduction of mesopore system into zeolite crystals is always deemed to be an effective strategy to improve diffusion and acidic accessibility. In this work, a hierarchically structured ZSM-5 with an ultra-small intracrystalline mesopore structure was prepared by using lysine as a pore-forming agent via a hydrothermal crystallization procedure. The structured and textured properties of the as-synthesized samples were characterized by XRD, SEM, EDS, TEM, NH3-TPD, FT-IR and N2 adsorption–desorption isothermals. The results showed that a purely-phased hierarchical ZSM-5 zeolite with a size of 2–6 nm mesopore can be obtained under the condition of lysine/Al2O3 = 2–8. The addition of lysine in the precursor not only generated an ultra-small mesopore system, but also had a significant effect on the acidity of the synthesized sample: With the increased amount of added lysine, the acid density and acid strength of the as-prepared zeolite catalyst were gradually weakened. The effects of the introduced hierarchical pore structure and the tailored acid sites on the catalytic performance of the catalysts were investigated during methanol dehydration to hydrocarbons reaction. The introduced hierarchical pores and the weakened strong acids significantly improved the stability of the catalyst. Meanwhile, the reduced acid density strongly inhibited hydrogen transfer of light olefins intermediate and then increased the selectivity toward light olefins on the hierarchical zeolite catalysts. [ABSTRACT FROM AUTHOR]

We synthesized ridaifen-B boron dipyrromethene (RID-B-BODIPY) using 2methyl-6-nitro benzoic anhydride (MNBA)-mediated dehydration condensation reaction between amino alkyl-tethered RID and BODIPY FL. Comparative experiments between dicyclohexylcarbodiimide (DCC) and MNBA for their coupling reactions demonstrated that MNBA is an effective condensation reagent for amines and BODIPY FL. A cell staining study with RID-B-BODIPY showed intracellular localization of BODIPY FL fluorescence, attributed to the RID-B structure, indicating the successful development of a tool for analyzing intracellular molecular behavior efficiently. [ABSTRACT FROM AUTHOR]

Tetrahydroquinolines are key structures in a variety of natural products with diverse pharmacological utilities and other applications. A series of 3,4-diaryl-5,7-dimethoxy-1,2,3,4-tetrahydroquinolines were synthesized in good yield by reacting 3-aryl-5,7-dimethoxy-2,3-dihydroquinolin-4-ones with different Grignard reagents followed by the dehydration of the intermediate phenolic compounds. Subsequent reduction and deprotection were carried out to achieve the desired tetrahydroquinolone moiety. The lead compound 3c showed low micromolar inhibition of various cancer cell lines. Demethylation under different reaction conditions was also investigated to afford the corresponding monohydroxy analogues. [ABSTRACT FROM AUTHOR]

Colemanite, the most significant commercially available borate mineral with calcium content, exhibits versatile applications and is widely used in glass, textiles, ceramics, detergents, and other industries. Investigating the dehydration characteristics, kinetics, and thermodynamics of this borate mineral is important to improve its performance because of its usage in different industries. This study involves a combination of characterization and thermal dehydration kinetics of colemanite results. First, colemanite is analyzed structurally and morphologically through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Then, different heating rates were applied to investigate the thermal behavior of the colemanite using thermogravimetric analysis (TGA). Based on the obtained thermograms, the dehydration zone was selected for kinetic and thermodynamic analysis using conversional kinetic methods. The average activation energies were calculated as 64.1±4.3, 59.6±3.9, 59.9±3.7, and 60.0±4.1 kJ/mol for Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, Starink, and Tang models, respectively. Through the thermodynamic analysis, it was found that the dehydration of colemanite was a non-spontaneous and endothermic process. [ABSTRACT FROM AUTHOR]

Hydration and dehydration reactions play pivotal roles in plate tectonics and the deep water cycle, yet many facets of (de)hydration reactions remain unclear. Here, we study (de)hydration reactions where associated solid density changes are predominantly balanced by porosity changes, with solid rock deformation playing a minor role. We propose a hypothesis for three scenarios of (de)hydration front propagation and test it using one‐dimensional hydro‐mechanical‐chemical models. Our models couple porous fluid flow, solid rock volumetric deformation, and (de)hydration reactions described by equilibrium thermodynamics. We couple our transport model with reactions through fluid pressure: the fluid pressure gradient governs porous flow and the fluid pressure magnitude controls the reaction boundary. Our model validates the hypothesized scenarios and shows that the change in solid density across the reaction boundary, from lower to higher pressure, dictates whether hydration or dehydration fronts propagate: decreasing solid density causes dehydration front propagation in the direction opposite to fluid flow while increasing solid density enables both hydration and dehydration front propagation in the same direction as fluid flow. Our models demonstrate that reactions can drive the propagation of (de)hydration fronts, characterized by sharp porosity fronts, into a viscous medium with zero porosity and permeability; such propagation is impossible without reactions, as porosity fronts become trapped. We apply our model to serpentinite dehydration reactions with positive and negative Clapeyron slopes and granulite hydration (eclogitization). We use the results of systematic numerical simulations to derive a new equation that allows estimating the transient, reaction‐induced permeability of natural (de)hydration zones. Plain Language Summary: We investigate reactions of hydration, which is the incorporation of water into a rock, and dehydration, which is the liberation of water from a rock, with simple mathematical models. These reactions are critical in understanding processes like plate tectonics, but many aspects of how hydration or dehydration fronts move through a rock are unclear. Our research focuses on reactions where changes in density are mostly balanced by changes in pore space, termed porosity, rather than the deformation of the solid rock. We developed mathematical models that combine fluid flow, rock deformation, and hydration/dehydration reactions. We derived simple equations that predict changes in porosity during hydration and dehydration, even when the solid rock deforms simultaneously. We found that whether a rock hydrates or dehydrates depends on how its solid density changes with increasing pressure during the reaction. By systematically studying our model, we discovered that the speed of hydration and dehydration is not influenced by the interval of fluid pressure over which the reaction occurs or the relationship between porosity and permeability. We present an equation that can be used to estimate permeability from natural (de)hydration zones. Key Points: (De)hydration fronts propagate into zero‐permeability rock if the solid density of the reactant is smaller than the one of the productExternal fluid flux compensates the imbalance between fluid generated/consumed by reaction and fluid needed to fill generated porosityResults of systematic numerical simulations allow estimating the transient, reaction‐induced permeability of natural (de)hydration zones [ABSTRACT FROM AUTHOR]

5‐Hydroxymethylfurfural (HMF) was transformed into 2,5‐diformylfuran (DFF) with nitric acid as the oxidant. The initial HMF content was as high as 12.5 wt %, and water was the sole solvent. This is an intensely exothermic reaction along with the emission of NO2 gas. A high DFF yield of 83.2 % was achieved if the oxidation ability of nitric acid matched with the requirement of target oxidation reaction while mismatched those of side reactions by regulating the initial concentration of nitric acid (59.5 wt %) and reaction temperature (50–60 °C). The oxidation reaction of HMF, overoxidation of HMF, and skeleton‐cracking reaction of FDCA preferred concentrated HNO3, hot HNO3, and concentrated or hot HNO3, respectively. After liquid‐liquid extraction, filtration, and column chromatography, light‐yellow DFF powders with purity of 92.1 wt % and isolated yield of 40.2 % were obtained and confirmed by NMR, FTIR, UV‐Vis, and elemental analysis. HMF was the dominant impurity due to its affinity to DFF. In addition, chromogenic substances were obtained as a byproduct, and they were potential pH indicators. These chromogenic substances had highly conjugated molecular structures, and they were generated via successive β‐protonation‐based ring‐opening reaction of HMF, aldol reaction, and dehydration reaction. [ABSTRACT FROM AUTHOR]

D-K-type bauxite from Guizhou can be used as an unburned ceramic, adsorbent, and geopolymer after low-temperature calcination. It aims to solve the problem where the color of the D–K-type bauxite changes after calcination at different temperatures. Digital image processing technology was used to extract the color characteristics of bauxite images after 10 min of calcination at various temperatures. Then, we analyzed changes in the chemical composition and micromorphology of bauxite before and after calcination and investigated the correlation between the color characteristics of images and composition changes after bauxite calcination. The test results indicated that after calcining bauxite at 500 °C to 1000 °C for 10 min, more obvious dehydration and decarburization reactions occurred. The main component gradually changed from diaspore to Al2O3, the chromaticity value of the image decreased from 0.0980 to 0.0515, the saturation value increased from 0.0161 to 0.2433, and the brightness value increased from 0.5890 to 0.7177. Studies have shown that changes in bauxite color characteristics are strongly correlated with changes in composition. This is important for directing bauxite calcination based on digital image processing from engineering viewpoints. [ABSTRACT FROM AUTHOR]

Microbial non-phosphorylative oxidative pathways present promising potential in the biosynthesis of platform chemicals from the hemicellulosic fraction of lignocellulose. An L-arabinonate dehydratase from Rhizobium leguminosarum bv. trifolii catalyzes the rate-limiting step in the non-phosphorylative oxidative pathways, that is, converts sugar acid to 2-dehydro-3-deoxy sugar acid. We have shown earlier that the enzyme forms a dimer of dimers, in which the C-terminal histidine residue from one monomer participates in the formation of the active site of an adjacent monomer. The histidine appears to be conserved across the sequences of sugar acid dehydratases. To study the role of the C-terminus, five variants (H579A, H579F, H579L, H579Q, and H579W) were produced. All variants showed decreased activity for the tested sugar acid substrates, except the variant H579L on D-fuconate, which showed about 20% increase in activity. The reaction kinetic data showed that the substrate preference was slightly modified in H579L compared to the wild-type enzyme, demonstrating that the alternation of the substrate preference of sugar acid dehydratases is possible. In addition, a crystal structure of H579L was determined at 2.4 Å with a product analog 2-oxobutyrate. This is the first enzyme-ligand complex structure from an IlvD/EDD superfamily enzyme. The binding of 2-oxobutyrate suggests how the substrate would bind into the active site in the orientation, which could lead to the dehydration reaction. Key points: • Mutation of the last histidine at the C-terminus changed the catalytic activity of L-arabinonate dehydratase from R. leguminosarum bv. trifolii against various C5/C6 sugar acids. • The variant H579L of L-arabinonate dehydratase showed an alteration of substrate preferences compared with the wild type. • The first enzyme-ligand complex crystal structure of an IlvD/EDD superfamily enzyme was solved. [ABSTRACT FROM AUTHOR]

Increases in temperature and pressure caused by rapid burial of sediments seaward of the Sumatra subduction zone have been hypothesized to trigger dehydration reactions that diagenetically strengthen sediments and contribute to the formation of an over‐pressured pre‐décollement, which together facilitate the occurrence of large shallow earthquakes. We present paleomagnetic, rock magnetic, and electron microscopic analyses from drill cores collected offshore Sumatra at Site U1480 during IODP Expedition 362 that support this hypothesis. The older pre‐fan units (Late Cretaceous to early Paleocene) were deposited when Site U1480 was moving rapidly northward with the Indian plate from a paleolatitude of 50° to 30°S, which would equate to expected absolute paleomagnetic inclinations of 70°–43°. Most of the older pre‐fan sediments, however, have shallow observed inclinations (shallower than ±20°), indicating that the sediments were overprinted when Site U1480 was located near the paleoequator, as it has been since the early Oligocene. Electron microscopic observations reveal that the pre‐existing detrital magnetite grains have undergone pervasive dissolution and alteration by hydrothermal fluids. The diagenesis observed is consistent with mineral dehydration, possibly driven by rapid burial of pelagic sediments by the ∼1250 m thick Nicobar Fan sequence. In addition, the elevated burial temperature also facilitated the smectite to illite conversion reaction. We hypothesize that chemical reactions resulted in the formation of fine‐grained magnetite that records a chemical remanent magnetization overprint. This overprint is consistent with the alteration occurring after burial by the thick Nicobar Fan sequence sometime in the past few million years. Plain Language Summary: Sediments and rocks commonly contain magnetic minerals that record the direction and intensity of Earth's magnetic field as they are being emplaced, thus preserving an ancient record of the geomagnetic field. Subsequent alteration of the magnetic minerals caused by heating and/or fluid circulation can result in the acquisition of secondary magnetizations (i.e., remagnetization) that may overprint or completely reset the primary ancient magnetization. Such remagnetization provides evidence of the physical and chemical changes that have occurred. Here through paleomagnetic, rock magnetic, and microscopic analyses of the deeper older (pre‐fan) stratigraphic sequence cored offshore Sumatra, we find that hydrothermal fluids, resulting from mineral dehydration driven by rapid burial of this sequence by younger, thick Nicobar Fan sediments, led to pervasive secondary remagnetization. Consequently, the newly formed magnetite recorded a much younger paleomagnetic field, leaving a shallow overprint that probably occurred sometime in the past few million years. The dehydration reactions also increased the strength of the sediments entering the subduction zone and aided in the formation of slip surfaces (called décollements), possibly contributing to the shallow, large earthquakes that have generated tsunamis off Sumatra. Key Points: The 60–67 Ma pre‐fan sediments offshore Sumatra were most likely remagnetized since deposition of the Nicobar Fan sediments, which began at ∼9 MaRemagnetization of pre‐fan sediments caused by mineral dehydration may be linked to shallow seismogenic slip off SumatraMagnetic properties of input sediments in the subduction margin record conditions that may have facilitated the generation of earthquakes [ABSTRACT FROM AUTHOR]

The objective of this research was to convert xylose into furfural using flax straw‐based bifunctional solid acid catalyst. The catalyst was synthesized by impregnation‐carbonization and sulfonation processes. The characterization of biochar, Al‐biochar, and sulfonated Al‐biochar catalyst were carried out by using Brunauer–EmmetTeller (BET), Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and thermogravimetric analysis (TGA). The results showed that the surface area, total acid density, and SO3H density of sulfonated Al‐biochar catalyst were 516.03 m2/g, 4.767 ± 0.23 mmol/g and 1.033 ± 0.1 mmol/g, respectively. The result of FTIR indicated that the presence of the different functional groups such as the phenolic group (‐OH), carboxylic group (‐COOH), sulfoxide group (‐SO3H), and Al‐O‐Al on the surface of the prepared catalyst. The catalytic performance of the synthesized catalyst was evaluated in a biphasic system of water and 2‐methyl tetra hydro furan. The effects of dehydration reaction parameters (reaction temperature, reaction time, and catalyst loading) on the formation of furfural were also studied. The maximum furfural formation was obtained at 180°C, 2 hr, and 0.2 gm of catalyst loading. Under this condition, the yield of furfural was around 64.7%, with a selectivity of 88.0%. The study demonstrated the effectiveness of the catalyst in the transformation of xylose into furfural. [ABSTRACT FROM AUTHOR]

In this work, the microstructure evolution and corrosion performance of additively manufactured GH4099 superalloy were investigated. The alloy samples were prepared by selective laser melting (SLM) technology with different laser power and scanning speed. The results showed that the GH4099 prepared by SLM had a fine grain structure, and the average grain size of all samples is below 18 μm. The relative density of SLMed samples first rose and then fell as the volume density increased. Under the process conditions of P = 170 W and V = 800 mm/s, sample N2 possessed the highest relative density and the minimum pores. In addition, the electrochemical test results indicated that sample N2 exhibited the best corrosion resistance, and its corrosion potential (ECorr) and corrosion current density (ICorr) were − 0.287 V and 0.149 μA·cm−2, respectively. The relative density and pores of the alloys were the main reason for the difference in corrosion properties. In particular, the irregular pores caused by lack of fusion were regarded as the initiation site of pitting and crack expansion, which has a greater effect on corrosion resistance than spherical pores. According to XPS results, the passivation film mainly consists of oxides and hydroxides of Ni, Cr, Co, and Al. The hydroxides of Ni, Cr, Co, and Al constituted the outer layer of the passivation film. After the dehydration reaction of hydroxides, their oxides formed the inner layer of the passivation film. In addition, the evolution of the passivation film including the formation and breakdown of the passivation film was also discussed. [ABSTRACT FROM AUTHOR]

Inorganic perovskites, with Cs+ substituting volatile organic components, show great promise in photovoltaic applications due to their outstanding optoelectronic properties and thermal stability. However, the black‐to‐yellow phase transition of CsPbI3 remains a challenge for realizing high‐performance inorganic perovskite solar cells (IPSCs). Herein, an effective approach is reported via incorporating the self‐assembled molecule Me‐4PACz to synergistically stabilize the [PbI6]4− octahedra and form a hydrophobic layer at interface and grain boundaries. An in situ dehydration condensation reaction of Me‐4PACz is observed during film annealing, which favors the reduction of undesired aggregation of Me‐4PACz in humid air, thus leading to enhanced anchoring interaction and more effective hydrophobic protection of CsPbI3. Therefore, the air‐processed CsPbI3 perovskite films show dramatically improved phase purity and humid stability. This strategy also improves the energy level alignment between perovskite and charge transport layers. As a result, a champion efficiency of 20.21% is realized, representing one of the highest reported values for air‐processed inverted IPSCs. Furthermore, it is demonstrated that by combining Me‐4PACz with the previously reported ethacridine lactate (EAL) additive, the device performance can be further boosted to 21.38%, which is a record efficiency for the inverted IPSCs reported to date. [ABSTRACT FROM AUTHOR]

The conversion of Methyl 3‐hydroxypropionate (3‐HPM) to 1,3‐propanediol (1, 3‐PDO) is an important step in the pathway towards the longterm sustainable production of the ethylene oxide hydroesterification. However, 3‐HPM is prone to side reactions like hydroxyl β‐dehydration and low reaction efficiency, which hinders its development. This study presents the first‐ever report on highly efficient gallium‐promoted Cu/SiO2 catalysts prepared using ethanol‐assisted ammonia‐evaporation (Et‐AE) for converting 3‐HPM to 1,3‐PDO. The prepared Cu‐1Ga/SiO2 catalyst exhibited satisfactory catalytic activity and 1,3‐PDO selectivity in the hydrogenation reaction, with a conversion of 3‐HPM of 94 % and a selectivity to 1,3‐PDO of 91 %. The characterisation results show that the addition of Ga increases the specific surface area and the pore volume of the catalyst, and also increases the dispersion of the Cu species. And the promotional effect likely originates from interactions between Ga3+ and Cu0 species though enhanced ability of the latter to activate H2. In addition, the introduction of Ga into the catalyst increases the interaction between Cu and the support, making it more difficult for Cu+ to be completely reduced to Cu0. This increases the content of Cu+ in the catalyst, which is beneficial for improving the activity and stability of the catalyst. This study investigates modifying Cu catalysts to provide guidelines for obtaining high performing hydrogenation catalysts. [ABSTRACT FROM AUTHOR]

Chromium and molybdenum incorporated MgO and MgO–C catalysts were synthesized for hydrogen production from a non-oxidative ethane dehydration reaction. Hydrogen production studies were carried out using a microwave-heated reactor system. The study investigated the effects of reaction temperature, type of active metal, and catalyst preparation method (physical mixture or core–shell structure) on hydrogen selectivity and ethane conversion during dehydrogenation reactions. The results showed that the optimal reaction temperature for the non-oxidative ethane dehydration reaction was 450 °C. Above this temperature, the selectivity of undesired byproducts increased. Catalysts containing molybdenum exhibited higher ethane conversion. Moreover, a comparison of MgO–C-supported catalysts with MgO-supported catalysts revealed that the core–shell catalysts exhibited superior ethane conversion. Notably, the 5Mo@MgO–C catalyst demonstrated exceptional catalytic activity, achieving a high ethane conversion rate of 72% along with excellent stability. [ABSTRACT FROM AUTHOR]

Aiming to optimize the product distribution of the Cu–Al catalytic system in the oxalate hydrogenation reaction as a way to optimize and improve the product structure of the coal-to-ethylene glycol process (Coal-Oxalate-EG), the researchers have investigated the two anchoring sites for anchoring the Cu component that is available in the Al2O3 support. The results show that the catalyst xSB synthesized from Al2O3 enriched with surface –OH functional groups is superior to the catalyst xSol synthesized from Al2O3 enriched with Al3+Penta sites for oxalate conversion, whereas xSol outperforms the xSB catalyst for the formation of alcohol-ether ester chemicals. Using diethyl oxalate (DEO) as feedstock, the reaction temperature of the 1Sol catalyst (235 °C) was higher than that of the 1SB catalyst (205 °C) for the conversion of the same amount of DEO at the same Cu loading. Meanwhile, the chemical selectivity of alcohol ether esters was higher for the 1Sol catalyst (~ 35%) than for the 1SB (~ 20%). Detailed characterization (XRD, NH3-TPD, XPS, in-situ FTIR, TEM, etc.) shows that the Al3+Penta sites are mainly present in the bulk phase of Al2O3, and the number of Al3+Penta sites present on the surface of the carriers is only sufficient to maintain the low content of Cu species in a highly dispersed state. A certain number of Al–OH is still required for the anchoring of the Cu species to the Al2O3 support surface. Therefore, hydroxyl-rich SB carriers are more favorable for the high dispersion of Cu species. Meanwhile, the stronger LAS distributed on the surface of the hydroxyl-rich SB carrier will lead to the decomposition or dehydration of the raw materials and intermediates during the reaction process, resulting in the formation of lower molecular weight products, which is unfavorable to the formation of the alcohol-ether ester products. Based on the detailed reaction data and characterization, a more complete product formation pathway of oxalate in the Cu–Al catalytic system is given, which provides a certain theoretical basis for the development of new coal-based chemical pathways. [ABSTRACT FROM AUTHOR]

This article discusses the use of iodine(III)-mediated ring-contraction reactions in both halogenated and non-halogenated solvents. The study compares the yields of ring-contraction reactions using different solvents and investigates the behavior of different derivatives of 1,2-dihydronaphthalene. The results show that using halogenated solvents leads to higher yields. The article also provides a detailed account of the synthesis and purification of various organic compounds, including their yields, physical properties, and spectroscopic data. Additionally, it provides information on the synthesis and characterization of three specific compounds, along with supporting information for further reference. [Extracted from the article]

A series of solvatomorphic structures of the anti-inflammatory drug diclofenac (dcfn−) and the dense hydrogen bond donor propane-1,3-diaminium (H2pn2+) are reported. Single crystal X-ray diffraction shows each structure contains a dcfn2·H2pn formula unit (1) with solvent of crystallisation [1·2H2O, 1·3H2O, 1·2MeOH, 1·EtOH·2H2O, 1·iPrOH, 1·2DMSO]. The propane-1,3-diaminium molecules evoke extensive networks of hydrogen-bonded interactions with the solvates and the dcfn carboxylate groups. All structures are lamellar with hydrophilic solvate-containing sheets separating hydrophobic layers of aromatic dcfn moieties. Supporting characterisations by powder X-ray diffraction, Fourier transform infrared and 1H NMR spectroscopies, thermal analysis (TG–DSC) and elemental microanalysis were used to reveal the sometimes delicate phase distributions amongst this set of compounds. TG–DSC showed a consistent pattern across the water and alcohol-containing compounds with desolvation occurring before melting to an anhydrous ionic liquid form around 140–150 °C. Heating to approximately 200 °C induces a minor dehydration reaction that covalently links diclofenac and propan-1,3-diaminium molecules via amide bond formation. A mechanochemical synthetic route to 1·3H2O was determined and this compound was selected for study by gravimetric water vapour adsorption. These studies showed the lamellar structure of 1·3H2O displays reversible but imperfect water adsorption between 0% and 50% relative humidity, which is ascribed to some crystal fatigue. This work expands crystal engineering strategies for new and existing active pharmaceutical ingredients to low molecular weight diamines. [ABSTRACT FROM AUTHOR]

Hierarchical SAPO-34 zeolite catalysts were successfully synthesized via a one-step hydrothermal synthesis approach with the assistance of excess triethylamine (TEA). Compared with conventional SAPO-34 (SP-T3), SAPO-34 synthesized with a TEA/Al2O3 molar ratio of 9 (SP-T9) presents high catalytic performance in the ethanol dehydration reaction due to its pseudocubic morphology with abundant butterfly-like large secondary pores and slightly decreased surface acidity. Afterwards, a cost-effective and green route is developed for synthesizing hierarchical SAPO-34 catalysts by recycling waste mother liquids. In recycling processes, residual organic templates in the mother liquids are reused in the next synthesis of SAPO-34 without adding fresh templates. After three recycles of mother liquids, the synthesized SP-R3 catalyst still retains its high crystallinity, hierarchical structure, moderate acidity, and excellent catalytic performance in ethanol dehydration as compared to the initial SP-T9 catalyst. [ABSTRACT FROM AUTHOR]

Polar stratospheric clouds (PSCs) form in polar regions, typically between 15 and 25 km above mean sea level, when the local temperature is sufficiently low. PSCs play an important role in the ozone chemistry and the dehydration and denitrification of the stratosphere. Lidars with a depolarization channel may be used to detect and classify different classes of PSCs. The main PSC classes are water ice, nitric acid trihydrate (NAT), and supercooled ternary solutions (STSs), the latter being liquid droplets consisting of water, nitric acid, and sulfuric acid. PSCs have been observed at the lidar observatory at Concordia Station from 2014 onward. The harsh environmental conditions at Concordia during winter render successful lidar operation difficult. To facilitate the operation of the observatory, several measures have been put in place to achieve an almost complete remote control of the system. PSC occurrence is strongly correlated with local temperatures and is affected by dynamics, as the PSC coverage during the observation season shows. PSC observations in 2021 are shown as an example of the capability and functionality of the lidar observatory. A comparison of the observations with the satellite-borne CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) lidar has been made to demonstrate the quality of the data and their representativeness for the Antarctic Plateau. [ABSTRACT FROM AUTHOR]

Antigorite is the high‐temperature member of the serpentine group minerals and is broadly considered a primary carrier of water in the subducting oceanic lithosphere. It has a wavy crystal structure along its a‐axis and several polysomes with different m‐values (m = 13–24) have been identified in nature. The m‐value is defined as the number of tetrahedra in one wavelength and is controlled by the misfit between the octahedral and tetrahedral layers. The degree of misfit primarily depends on the volumes of the MgO6 octehedra and SiO4 tetrahedra within the layers, which vary as a function of pressure and temperature. However, it is not well understood which m‐values of antigorite are stable at different pressure and temperature conditions. To investigate the pressure dependence of the stability of different m‐values in antigorite, we performed first‐principles calculations for several polysomes (m = 14–19) at high pressure from 0 to 14 GPa and compared their enthalpies at static 0 K. We found that although the energy differences between polysomes are small, polysomes with larger m‐values are more stable at ambient pressure, while polysomes with smaller m‐values are more stable at elevated pressures. This suggests that the structure of antigorite in the oceanic lithosphere subducting into the deep Earth may gradually evolve into a different polysome structure than the antigorite samples observed at ambient or near‐surface pressure conditions. These changes in the m‐values are accompanied by a minor dehydration reaction. By modulating the available amount of free water in the system, antigorite polysomatism may influence the distribution of intermediate‐depth seismicity, such as the observance of double seismic zones. Plain Language Summary: Antigorite is a hydrous mineral known for being an important carrier of water into the Earth's interior and a seismicity trigger at intermediate‐depths down to ∼200 km. However, its crystal structure is complex (e.g., Uehara, 1998), and thus it is not well understood which structural variant (polysome) of antigorite is stable or dominant at high pressures and temperatures during subduction. In this study, several crystal structures of antigorite were calculated by first‐principles calculations, and their enthalpies (i.e., Gibbs free energy of a system at static 0 K) were compared to determine the stable structure as a function of pressure. The results indicate that the structure and chemical composition of antigorite likely changes under high pressure, resulting in the gradual release of water during the subduction process. As antigorite is thought to be the main trigger of seismicity in the subducting lithospheric mantle, its metasomatism may contribute to explain the reported distributions of intermediate‐depth earthquakes. Key Points: Antigorite crystal structures with various values of m (14–19) were determined by first‐principles calculation under pressureThe relative enthalpy shows that antigorite with smaller m‐values are stabilized with increased pressureAntigorite in suducting slabs may gradually dehydrate under high pressure as a result of changes to stable m‐values [ABSTRACT FROM AUTHOR]

An intramolecular electrochemical dehydration reaction of dicarboxylic acids to their cyclic anhydrides is presented. This electrolysis allows dicarboxylic acids as naturally abundant, inexpensive, safe, and readily available starting materials to be transformed into carboxylic anhydrides under mild reaction conditions. No conventional dehydration reagent is required. The obtained cyclic anhydrides are highly valuable reagents in organic synthesis, and in this report, we use them in‐situ for acylation reactions of amines to synthesize amides. This work is part of the recent progress in electrochemical dehydration, which – in contrast to electrochemical dehydrogenative reactions for example – is an underexplored field of research. The reaction mechanism was investigated by 18O isotope labeling, revealing the formation of sulfate by electrochemical oxidation and hydrolysis of the thiocyanate‐supporting electrolyte. This transformation is not a classical Kolbe electrolysis, because it is non‐decarboxylative, and all carbon atoms of the carboxylic acid starting material are contained in the carboxylic anhydride. In total, 20 examples are shown with NMR yields up to 71 %. [ABSTRACT FROM AUTHOR]

Zinc‐organic batteries (ZOBs) are receiving widespread attention as up‐and‐coming energy‐storage systems due to their sustainability, operational safety and low cost. Charge carrier is one of the critical factors affecting the redox kinetics and electrochemical performances of ZOBs. Compared with conventional large‐sized and sluggish Zn2+ storage, non‐metallic charge carriers with small hydrated size and light weight show accelerated interfacial dehydration and fast reaction kinetics, enabling superior electrochemical metrics for ZOBs. Thus, it is valuable and ongoing works to build better ZOBs with non‐metallic ion storage. In this review, versatile non‐metallic cationic (H+, NH4+) and anionic (Cl−, OH−, CF3SO3−, SO42−) charge carriers of ZOBs are first categorized with a brief comparison of their respective physicochemical properties and chemical interactions with redox‐active organic materials. Furthermore, this work highlights the implementation effectiveness of non‐metallic ions in ZOBs, giving insights into the impact of ion types on the metrics (capacity, rate capability, operation voltage, and cycle life) of organic cathodes. Finally, the challenges and perspectives of non‐metal‐ion‐based ZOBs are outlined to guild the future development of next‐generation energy communities. [ABSTRACT FROM AUTHOR]

The document titled "Thresholds of Temperature and Time for Mars Sample Return: Final Report of the Mars Sample Return Temperature-Time Tiger Team" provides valuable information on the potential risks and effects of exposing Mars Sample Return (MSR) samples to specific temperature ranges. The report was conducted by a team of scientists from various disciplines to assess the impact of temperature on the integrity and scientific value of the samples. It discusses the potential reactions and processes that may occur when samples collected from Mars are heated, including the release of volatiles, chemical reactions, and effects on inorganic and organic materials. The document also emphasizes the importance of preserving hydrated minerals and the potential impact of temperature changes on the scientific analysis and interpretation of the samples. Additionally, it discusses the potential risks and challenges associated with the MSR mission, including the presence of terrestrial contaminants and the assessment of potential Martian life in the samples. Overall, this document provides valuable insights for library patrons conducting research on Mars Sample Return and the impact of temperature on sample preservation and scientific analysis. [Extracted from the article]

High-performance Cu catalysts were developed for the selective hydrogenation of γ-butyrolactone (GBL) to 1,4-butanediol (BDO). Among the various catalysts prepared by ammonia evaporation (AE) and impregnation (IM) methods with silica or MFI zeolite supports, the 5% Cu-SiO2-AE catalyst was the best one. It exhibited 95% selectivity for BDO and 71% conversion of GBL after 2–8 h reaction at 200 °C and 4 MPa H2, with high stability in five-cycle runs. Comprehensive characterizations showed that the AE method favored generating nano Cu particles with an average size of 2.9 nm on the 5% Cu-SiO2-AE catalyst. The silica support derived from a sol demonstrated an advantage over the MFI zeolite in the preparation of a highly dispersed and stable Cu catalyst, in view of its anti-sintering and robust composition of Cu0, Cu+, and Cu2+ in the cycling operation. The reaction pathways for GBL to BDO over the Cu catalysts were found to commonly involve reversible reactions of hydrogenation and dehydrogenation, along with subsequent dehydration to form THF. The high performance of the Cu catalysts in the conversion of GBL to BDO was attributed to the high dispersion of Cu, the presence of stable active sites, and fewer strong acid sites in the catalyst. [ABSTRACT FROM AUTHOR]

Introduction: Embryo cryopreservation is a valuable technique used for preserving genetic resources for long periods. However, the survival rate of embryos is dependent on the method used. Therefore, in this study, we evaluated the efficiency of slow freezing method but with an additional dehydration step prior to freezing to overcome the formation of ice crystals. Methods: Oocytes collected from the ovaries of native Korean cattle subjected to in vitro fertilization were cultured for 7 days until the formation of expanded blastocysts. Before freezing, the blastocysts were placed in four pre-equilibration media: a control medium with no addition of sucrose, and three experimental media with the addition of 0.1, 0.25, and 0.5 M sucrose, respectively. Then, the pre-equilibrated embryos were frozen. Embryo survival and hatching rates were evaluated morphologically at 24, 48, and 72 h after thawing. Immunofluorescence staining, terminal deoxynucleotidyl transferasemediated dUTP nick end labeling (TUNEL) assay, and gene expression analysis of the re-expanded blastocytes were examined 24 h after freeze-thawing. Results: The survival rate was significantly higher in the 0.1 M group than in the control group (p < 0.05), and the hatching rate at 72 h was significantly higher in the 0.25 and 0.5 M groups than in the control group (p < 0.05). TUNEL-positive cells were significantly lower in the 0.25 M group than in the control group (12.5 ± 0.9 vs. 8.3 ± 0.8; p < 0.05). The gene expression of BCL2 associated X, heat shock protein 70 kDa, and aquaporin 3 in the 0.25 M group was significantly lower than that in the control group (p < 0.05). Conclusion: Our study revealed that treatment with 0.25 M sucrose before slow freezing improved the viability of bovine embryos after freeze-thawing. [ABSTRACT FROM AUTHOR]

Aldoxime dehydratases (Oxds) have received considerable attention recently due to their application in the asymmetric synthesis of nitriles without cyanide by catalyzing the dehydration of aldoxime. However, the low stability of Oxds remains a huge obstacle to achieving high conversions and productivities of hydrophobic substrates. OxdPsp was immobilized on a macroporous adsorption resin (IOP) via an ATPS coupled with in situ immobilization. IOP-catalyzed dehydration of 2-phenylpropanal oxime (1) to prepare (S)-2-phenylpropanenitrile ((S)-2) was successfully performed with 95.7% yield, 94.1% ee and 98.6% conversion. The enriched (S)-nitrile (ee 94.1%) was obtained by using (E)-enriched aldoximes (E/Z = 97/3) as the substrate, which is consistent with the Gröger enantiopreference rule. A kinetic model to predict the dehydration catalyzed by IOP was established with an average deviation of 7.6%. The IOP-catalyzed dehydration reaction follows a sequential mechanism including substrate and product inhibition. Developing a kinetic model is a key step in the application of artificial intelligence in chemical engineering. After three recycling steps of IOP, the yield of (S)-2 still reached 83.6%, indicating that the stability of IOP was greatly enhanced, which was attributed to employing an organic solvent with a higher lg P value as the working medium and the immobilization protocol. [ABSTRACT FROM AUTHOR]

Catalytic pyrolysis of low-rank coal is currently an effective method for producing high-quality tar and gas. In this study, catalytic upgrading of volatiles from Naomaohu (NMH) coal pyrolysis has been conducted in a two-stage fixed-bed reactor using combined CaO and Ni/olivine (Ni-loaded olivine) catalysts. The effect of catalyst distribution modes and catalytic temperature on the tar and gas quality has been investigated. Simulated distillation and GC-MS analysis have been used to investigate the distribution of tar components. The results indicated that the light oil fraction in tar dramatically increased due to the combination of CaO and Ni/olivine. The CaO-Ni/olivine mode is especially better compared to the layouts of the Ni/olivine-CaO mode and the mixed mode. The CaO-Ni/olivine mode ensures a higher light fraction in tar at 69.3% and a light oil fraction at 29.8% at a catalytic temperature of 450 °C, while the heavy tar fraction decreased to 30.7%. Meanwhile, the contents of benzene (heteroatomic substituents) in tar significantly increased from 2.55% to 6.45% compared with the blank test. In this scenario, CaO breaks down macromolecular compounds in tar and cleaves long-chain esters to produce aliphatic hydrocarbons. These hydrocarbons are then dehydrogenated to produce lighter aromatic hydrocarbons over the CaO surface. Subsequently, the volatiles pass through the Ni/olivine catalysis, where ether compounds are produced by means of dehydration reactions. In addition, the CaO absorbs the CO2 in the pyrolysis gas, leading to an elevation of CH4 and H2 concentration. Particularly, the concentration of H2 significantly increased from 16.2% to 30.37%, while the concentration of CO2 significantly decreased from 37.9% to 10.57%. These findings suggest that the usage of combined CaO and Ni/olivine catalysts is beneficial for improving both the tar and gas quality. [ABSTRACT FROM AUTHOR]

The stability and breakdown of mineral phases in subducting slabs control the cycling of trace elements through subduction zones. Stability of key minerals and the partitioning of trace elements between these minerals and liquid phases of interests have been charted by natural sample analysis and experimental constraints. However, systematic study from arc front to far back arc has rarely shown that the expected geochemical variations of the slab liquid are actually recorded by natural samples. Complexities arise by uncertainties on the nature of the slab component (melts, fluids and supercritical liquids), source heterogeneities and transport processes. Using data from olivine-hosted melt inclusions sampled along and across the NE Japan and southern Kurile arcs, we demonstrate that experimentally and thermodynamically constrained phase stabilities in subducted materials indeed control the trace element signatures as predicted by these models and experiments. The main reactions that can be traced across arc are progressive breakdown of light rare earth element-rich accessory phases (e.g. allanite), enhanced dehydration of the lithospheric mantle (serpentine breakdown) and changes in the nature of the slab component. This work elucidates subduction zone elemental cycling in a well-characterized petrogenetic setting and provides important constraints on the interpretation of trace element ratios in arc magmas in terms of the prograde metamorphic reactions within the subducting slab. [ABSTRACT FROM AUTHOR]

Mesoporous nano-sized γ–Al2O3 and γ–Al2O3–CeO2 (20 wt% CeO2) catalysts were successfully synthesized through a sol–gel surfactant-free process, using cerium nitrate and aluminum nitrate as precursors. The obtained γ-aluminas were then characterized by scanning and transmission electron microscopy, powder X-ray diffraction, thermogravimetric analysis (TGA), and temperature-programmed desorption with ammonia. Afterward, the structural properties of the prepared catalysts were monitored through surface area analysis measurements. Finally, the catalytic activity of the obtained aluminas were studied in methanol dehydration reaction. Methanol conversion and selectivities to different products were measured at different reaction temperatures by gas chromatography. The optimum temperature of catalytic reaction in the presence of alumina-ceria was 300 °C due to 100% DME selectivity and 91% methanol conversion. [ABSTRACT FROM AUTHOR]

Two 2,4,6-trimethylaniline-based trifuloromethanesulfonate (trifluoromethanesulfonate) salts were synthesized and characterized by single-crystal X-ray diffraction. N,2,4,6-Tetramethylanilinium trifluoromethanesulfonate, [C10H14NH2+][CF3O3S-] (1), was synthesized via methylation of 2,4,6-trimethylaniline. N-Isopropylidene-N,2,4,6-tetramethylanilinium trifluoromethanesulfonate, [C13H20N+][CF3O3S-] (2), was synthesized in a two-step reaction where the imine, N-isopropylidene-2,4,6-trimethylaniline, was first prepared via a dehydration reaction to form the Schiff base, followed by methylation using methyl trifluoromethanesulfonate to form the iminium ion. In compound 1, both hydrogen bonding and p-p interactions form the main intermolecular interactions. The primary interaction is a strong N--H...O hydrogen bond with the oxygen atoms of the trifluoromethanesulfonate anions bonded to the hydrogen atoms of the ammonium nitrogen atom to generate a one-dimensional chain. The [C10H14NH2+] cations form dimers where the benzene rings form a p-p interaction with a parallel-displaced geometry. The separation distance between the calculated centroids of the benzene rings is 3.9129 (8) Å, and the interplanar spacing and ring slippage between the dimers are 3.5156 (5) and 1.718 Å, respectively. For 2, the [C13H20N+] cations also form dimers as in 1, but with the benzene rings highly slipped. The distance between the calculated centroids of the benzene rings is 4.8937 (8) Å, and interplanar spacing and ring slippage are 3.3646 (5) and 3.553 Å, respectively. The major intermolecular interactions in 2 are instead a series of weaker C--H...O hydrogen bonds [C...O distances of 3.1723 (17), 3.3789 (18), and 3.3789 (18) Å], an interaction virtually absent in the structure of 1. Fluorine atoms are not involved in strong directional interactions in either structure. [ABSTRACT FROM AUTHOR]

X-ray computed tomography has established itself as a crucial tool in the analysis of rock materials, providing the ability to visualise intricate 3D microstructures and capture quantitative information about internal phenomena such as structural damage, mineral reactions, and fluid–rock interactions. The efficacy of this tool, however, depends significantly on the precision of image segmentation, a process that has seen varied results across different methodologies, ranging from simple histogram thresholding to more complex machine learning and deep-learning strategies. The irregularity in these segmentation outcomes raises concerns about the reproducibility of the results, a challenge that we aim to address in this work. In our study, we employ the mass balance of a metamorphic reaction as an internal standard to verify segmentation accuracy and shed light on the advantages of deep-learning approaches, particularly their capacity to efficiently process expansive datasets. Our methodology utilises deep learning to achieve accurate segmentation of time-resolved volumetric images of the gypsum dehydration reaction, a process that traditional segmentation techniques have struggled with due to poor contrast between reactants and products. We utilise a 2D U-net architecture for segmentation and introduce machine-learning-obtained labelled data (specifically, from random forest classification) as an innovative solution to the limitations of training data obtained from imaging. The deep-learning algorithm we developed has demonstrated remarkable resilience, consistently segmenting volume phases across all experiments. Furthermore, our trained neural network exhibits impressively short run times on a standard workstation equipped with a graphic processing unit (GPU). To evaluate the precision of our workflow, we compared the theoretical and measured molar evolution of gypsum to bassanite during dehydration. The errors between the predicted and segmented volumes in all time series experiments fell within the 2 % confidence intervals of the theoretical curves, affirming the accuracy of our methodology. We also compared the results obtained by the proposed method with standard segmentation methods and found a significant improvement in precision and accuracy of segmented volumes. This makes the segmented computed tomography images suited for extracting quantitative data, such as variations in mineral growth rate and pore size during the reaction. In this work, we introduce a distinctive approach by using an internal standard to validate the accuracy of a segmentation model, demonstrating its potential as a robust and reliable method for image segmentation in this field. This ability to measure the volumetric evolution during a reaction with precision paves the way for advanced modelling and verification of the physical properties of rock materials, particularly those involved in tectono-metamorphic processes. Our work underscores the promise of deep-learning approaches in elevating the quality and reproducibility of research in the geosciences. [ABSTRACT FROM AUTHOR]

The tobacco waste generated from the tobacco agriculture and industry, including the discarded stem and leaf, often needs dehydration pretreatment before thermal conversion utilization. In order to study the water activity and migration of tobacco waste during the pretreatment process, TG-NMR (Thermogravimetric Nuclear Magnetic Resonance) was used to obtain the drying curves and LF-NMR (Low Field Nuclear Magnetic Resonance) T2 inversion spectrum at each stage of tobacco drying. Meanwhile, the variation pattern of pore distribution during the dehydration process of two types of tobacco waste has been obtained. Combined with the pore distribution changes, a possible spatial migration mode of water was proposed. The change of adsorption energy of water during tobacco drying was calculated, and verified the above hypothesis. This study results provide reference for the optimization of dehydration pretreatment process for different tobacco waste in order to reduce energy consumption during recycling of tobacco biomass. [ABSTRACT FROM AUTHOR]

Upcycling biodegradable polyester waste into value-added chemicals can not only avoid CO2 emissions but also achieve sustainable carbon recycling. Herein, we report a one-pot catalytic process to deconstruct polycaprolactone into 6-aminocaproic acid (EACA) and caprolactam (CPL), two monomers of nylon-6, using aqueous ammonia and Ru catalysts. No additional hydrogen is required, and the total yield of EACA and CPL could reach 90.2% using a ternary catalyst, Ru/CeO2/RGO, at 140 °C. It is verified that 6-hydroxyhexanoic acid and 6-hydroxyhexanoamide are the initial intermediates resulting from polycaprolactone decomposition, which undergo dehydrogenation, amination and re-hydrogenation to transform into EACA and 6-aminohexanoamide over the Ru catalyst. The hydrolysis of 6-aminohexanoamide produces EACA, and the reverse reaction between dehydration of EACA and hydrolysis of CPL results in their coexistence. The protocol demonstrated here provides a novel route to recycle polycaprolactone to valuable chemicals. [ABSTRACT FROM AUTHOR]

In this study, a zero‐gap flow‐through microfluidic reactor was constructed for the degradation of tetracycline and norfloxacin in water using a porous Ti/RuO2‐IrO2@Pt electrode as the anode and porous titanium plate as the cathode. The operation parameters included electrolyte type, electrolyte concentration, current density, initial concentration of pollutants and pH, were investigated. The degradation efficiency and energy consumption were calculated and compared with traditional electrolyzer. In the zero‐gap flow‐through microfluidic reactor, 100 % of both tetracycline and norfloxacin can be decomposed in 15 min, and high mineralization rate were achieved under the optimized reaction condition. And the reaction was consistent with pseudo‐first‐order kinetics with k value of 0.492 cm−1 and 1.010 cm−1, for tetracycline and norfloxacin, respectively. In addition, the energy consumption was 28.33 kWh ⋅ kg−1 TC and 8.36 kWh ⋅ kg−1 NOR, for tetracycline and norfloxacin, respectively, which was much lower than that of traditional electrolyzer. The LC–MS results showed that tetracycline underwent a series of demethylation, dehydration and deamination reactions, and the norfloxacin went through ring opening reaction, decarboxylation and hydroxylation reaction, and finally both produced CO2 and H2O. [ABSTRACT FROM AUTHOR]

In this study, an experimental strategy to obtain biochar and activated carbon from torrefied palm kernel shell as an efficient material for CO2 removal was evaluated. Biochar was obtained by slow pyrolysis of palm kernel shell at different temperatures (350 °C, 550 °C, and 700 °C) and previously torrefied palm kernel shell at different temperatures (220 °C, 250 °C, and 280 °C). Subsequently, activated carbons were prepared by physical activation with CO2 from previously obtained biochar samples. The CO2 adsorption capacity was measured using TGA. The experimental results showed that there is a correlation between the change in the O/C and H/C ratios and the functional groups –OH and C=O observed via FTIR in the obtained char, indicating that both dehydration and deoxygenation reactions occur during torrefaction; this favors the deoxygenation reactions and makes them faster through CO2 liberation during the pyrolysis process. The microporous surface area shows a significant increase with higher pyrolysis temperatures, as a product of the continuous carbonization reactions, allowing more active sites for CO2 removal. Pyrolysis temperature is a key factor in CO2 adsorption capacity, leading to a CO2 adsorption capacity of up to 75 mg/gCO2 for biochar obtained at 700 °C from non-torrefied palm kernel shell (Char700). Activated carbon obtained from torrefied palm kernel shell at 280 °C (T280-CHAR700-AC) exhibited the highest CO2 adsorption capacity (101.9 mg/gCO2). Oxygen-containing functional groups have a direct impact on CO2 adsorption performance due to electron interactions between CO2 and these functional groups. These findings could provide a new experimental approach for obtaining optimal adsorbent materials exclusively derived from thermochemical conversion processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Solvent recirculation is a feasible strategy to valorize the HTC aqueous waste. • HTC moderate temperatures favor additional hydrochar formation during recirculation. • HTC of blended biomasses enhances hydrochar recovery at 180 °C. • Process water recirculation promotes dehydration and decarboxylation reactions. • A significantly higher energy recovery is achieved by process water recirculation. This study aims at valorizing the residual aqueous phase from hydrothermal carbonization (HTC) of Sicilian agro-wastes in order to enhance the hydrochar recovery, positively affecting the process energy balance. Process waters (PW) obtained from HTC and co-HTC using orange peel waste and fennel plant residues were used as recycled solvent in experiments carried out at the temperatures of 180 and 230 °C. The results showed that an additional hydrochar formation was promoted during recirculation of solvent, leading to average increments of solid mass yield of 10.5 wt% for tests conducted at 180 °C and 3.9 wt% for 230 °C. After five consecutive recirculation phases in co-HTC runs, the hydrochar yield increased up to 18.2 wt%. The low H/C and O/C atomic ratios values, found after recirculation, indicate that organic acids, accumulated in the PW, may catalyze the process and promote the biomass deoxygenation by boosting dehydration and decarboxylation. The recovered PWs from conversion steps with deionized water were also carbonized in absence of the solid feedstock in order to quantify their contribution in hydrochar formation during recirculation and thus the synergistic interactions. After recirculation, energy recovery averagely augmented by more than threefold, showing that the proposed strategy could significantly improve the sustainability of HTC. [ABSTRACT FROM AUTHOR]

Bio-based acetaldehyde production by non-oxidative dehydrogenation of ethanol is a promising alternative for the fine chemistry industry, where acetaldehyde is an important part of the synthesis chain and co-production of hydrogen. In this paper, investigations on nickel containing alumina itterbia stabilized zirconia with microwave-assisted synthesis as catalysts for the ethanol dehydrogenation process to acetaldehyde are reported. Ni–xAl2O3–(100 − x)[Zr0,97Yb0,03]O2 (x = 35 and 65 mol%) were prepared by using microwave (MW) irradiation and by traditional heating steps during sol–gel preparation. The textural properties, structure, morphology, surface and phase composition, and RedOx properties (SEM–EDX, BET N2-physisorption, TG–DTA, XRD, EPR) of the samples were compared with the effect of the microwave-assisted synthesis and the Zr:Al ratio on the ethanol dehydrogenation is reported. Two synthesis routes were compared, and it was found that microwave pretreatment of hydrogel during sol–gel synthesis favors catalytic dehydrogenation, whereas catalysts prepared by pretreatment under uniform heating perform much worse. The microwave-assisted synthesis approach turned out to be more promising in terms of selectivity to acetaldehyde in the ethanol dehydrogenation due to form nickel oxide particles with strong support interaction in noncubic coordination catalyzing the ethanol dehydrogenation and at the same time to decrease the formation of nickel aluminate phase involved in competitive dehydration reaction to ethylene. Thus, the highest obtained selectivity to acetaldehyde was ≈ 70% at 400 °C on Ni–65AZ–MW sample. [ABSTRACT FROM AUTHOR]

A density functional theoretical (DFT) study is presented, implicating a 1O2 oxidation process to reach a dihydrobenzofuran from the reaction of the natural homoallylic alcohol, glycocitrine. Our results predict an interconversion between glycocitrine and an iso‐hydroperoxide intermediate [R(H)O+–O−] that provides a key path in the chemistry which then follows. Formations of allylic hydroperoxides are unlikely from a 1O2 'ene' reaction. Instead, the dihydrobenzofuran arises by 1O2 oxidation facilitated by a 16° curvature of the glycocitrine ring imposed by a pyramidal N‐methyl group. This curvature facilitates the formation of the iso‐hydroperoxide, which is analogous to the iso species CH2I+–I− and CHI2+–I− formed by UV photolysis of CH2I2 and CHI3. The iso‐hydroperoxide is also structurally reminiscent of carbonyl oxides (R2C=O+–O−) formed in the reaction of carbenes and oxygen. Our DFT results point to intermolecular process, in which the iso‐hydroperoxide's fate relates to O‐transfer and H2O dehydration reactions for new insight into the biosynthesis of dihydrobenzofuran natural products. [ABSTRACT FROM AUTHOR]

We study the interplay of the thermal structure within subducted oceanic slabs together with the stability fields of hydrous phases that control slab dehydration and the amount of water transported into the deeper mantle. We implement different published thermodynamic data for phase A and Mg‐sursassite into a model of 56 subduction zones and evaluate the effect of these phases on the global water budget. We modeled vertical fluid fluxes within the slab such that dehydration‐derived fluid was allowed to react with fluid‐undersaturated rocks in other parts of the slab. The effect of Mg‐sursassite on the global water budget is limited, because the Clapeyron slope of this dehydration reaction is steeper than most pressure‐temperature trajectories in subduction zones. Two sets of published thermodynamic data for phase A yield significantly different values for the amount of deeply subducted water, ranging between 8 × 108 Tg/Ma and 1.4 × 109 Tg/Ma. In some subduction zones, the differences span several orders of magnitude. The absolute modeled amount of deeply subducted water strongly depends on the depth and intensity of slab mantle hydration, but a comparison of modeled and experimental data indicates that the thermodynamic dataset that yielded higher values is more reliable and should be implemented in future thermodynamic models. Our results show that the stable phases around the choke point as well as the slope and position of the phase A‐out reaction influence the deep water release from the slab, but the slope and position of the phase A dehydration reaction mainly control the recycling of water into the deep mantle. Plain Language Summary: Water on our planet is constantly exchanged between the oceans and the interior of the Earth. This happens at subduction zones where hydrated oceanic crust is sinking into the Earth's mantle, thus bringing water to depths exceeding 300 km. We quantify this amount of water that is globally recycled into the deeper Earth in subduction zones through computer models that combine the temperature structure of the subducted rocks with the stability of hydrous phases. Knowledge about the global water budget is important to quantify the Earth's total water amount, to understand the water release from the subducting oceanic plate, and to interpret sea level changes in Earth's history. We compared thermodynamic datasets for two minerals, namely Mg‐sursassite and phase A, in the oceanic plate that can transfer large amounts of water into the deeper Earth. Our thermodynamic models show that the stability of phase A in the down going oceanic plate controls much of the recycled water in most subduction zones. Key Points: Mg‐sursassite has a limited influence on the global amount of subducted waterMg‐sursassite can transfer water to depths of up to 250 km and lead to deep dehydration and water release from the slabThe Clapeyron slope of the phase A dehydration reaction is sub‐parallel to many slab P‐T paths and mainly controls the deep water subduction [ABSTRACT FROM AUTHOR]

Dehydration reactions within subducted oceanic crust are important for fluid‐mediated element transfer within the subducting plate and potentially to the mantle wedge. The effects of metamorphic reactions and fluid flow on element recycling that occur during retrogression and exhumation of subducted continental crust from mantle depths are poorly understood. We study two metabasite pods with fresh eclogite cores and retrogressed amphibolite‐facies rims and surrounding host gneiss within the Western Gneiss Region (WGR), Norway, to better understand element mobility and mass transfer during exhumation of subducted continental crust. Bulk‐rock data were collected from samples taken across the pod and into the host gneiss. Phengite breakdown in eclogite and epidote recrystallization in veins and/or gneiss within pod cores contributed large ion lithophile elements and REE to retrogressed eclogite closest to the pod cores. In gneiss hosting the pods, phengite and epidote breakdown provided fluid that mediated elemental transfer and redistribution to the pod rim or tail. Compared to the studied pod in the southern WGR, the pod in the northern WGR underwent higher P‐T conditions, partial melting and higher strain rates. This resulted in the infiltration of external fluid farther into the pod interior from the rim and facilitated larger mass gain in trace elements in the amphibolite tail of the pod relative to fresh eclogite in the core. The results show clear evidence for retrogression dehydration reactions driving significant fluid‐mediated element redistribution as observed on the outcrop scale during exhumation following ultrahigh‐pressure metamorphism, which directly impacts element signatures within the exhuming crust. Plain Language Summary: A lot is not known about how fluids and metamorphic reactions recycle elements in continental crust as it is brought to the surface after being subducted to ∼100 km. We study two eclogite pods that are surrounded by gneiss in the Western Gneiss Region, Norway to study how different pressure‐temperatures (P‐T), deformation, and fluids control element movement in deep crust as it is exhumed. The pod cores have eclogite that record the rock conditions at ∼100 km, but the exteriors were altered during exhumation. We sampled transects from the pod cores to ∼20 m into the surrounding gneiss. Bulk‐rock and mineral trace‐element data show two situations of mineral breakdown that generated trace‐element‐rich fluid that reacted with and enriched metabasite in Rb, Sr, Ba, and light rare earth elements: (a) veins or gneiss in pod cores enriched adjacent eclogite, and (b) surrounding gneiss enriched the pod exteriors. As shown by the pod that experienced higher P‐T conditions and deformation than the second pod, larger amounts of elements were transferred into the pod rim, and fluid penetrated the pod, enriching eclogite near the pod rim. Clearly, exhumation conditions and mineral break‐down reactions are important for elemental recycling in crust during exhumation. Key Points: In the Western Gneiss Region, Norway, fluids redistribute elements during retrogression after ultrahigh‐pressure metamorphismRecrystallization of epidote‐group minerals and phengite in metabasite pod interiors facilitate elemental transfer within the podsHost gneiss‐derived fluids infiltrate amphibolite‐facies retrogressed pod rims, driving significant element redistribution and mass transfer [ABSTRACT FROM AUTHOR]

Pyrolysis technology is crucial for realizing waste bischofite resource utilization. However, previous studies overlooked the complexity of multistep pyrolysis, resulting in a lack of thorough knowledge of the pyrolysis behavior and kinetics. The pyrolysis products were characterized using XRD and FTIR to indicate the bischofite pyrolysis behavior. Additionally, the multistep kinetics was studied using the segmented single-step reaction (SSSR) and Fraser-Suzuki combined kinetic (FSCK) methods. The results show that the bischofite pyrolysis is divided into dehydration and hydrolysis. The former refers to removing crystalline water from MgCl2·nH2O (n = 4,6). At the same time, the latter is related to the removal of HCl, characterized by the strengthening of the Mg-O bond in the FTIR analysis and the emergence of MgOHCl·1.5H2O in the XRD examination. The two main stages are divided into three dehydration reactions (D-1, D-2, D-3) and three hydrolysis reactions (H-1, H-2, H-3) by DTG-DDTG or Fraser-Suzuki deconvolution. Compared with the SSSR method, the FSCK method has improved model repeatability for multistep kinetic parameters. Following Fraser-Suzuki deconvolution, the FSCK method creates almost the same activation energy results when using the Friedman (FR), Kissinger–Akahira–Sunose (KAS), and Vyazovkin (VZK). This work provides fundamental data to promote the maximizing waste bischofite resource utilization. [ABSTRACT FROM AUTHOR]