Search

An efficient synthetic procedure for the synthesis of isatins was found after careful analysis of the serendipitous results of the unexpected products obtained by aromatic nucleophilic substitution when it was attempted to introduce 6-fluoroisatins to the classic Pfitzinger reaction. Attentive analysis of these results led to elaborating a methodology for synthesizing electron-enriched isatins, including those with hydroxy-, alkoxy-, alkylthio-, and dialkylamino-substituted aromatic rings. Limitations of the method were established. The reaction conditions were optimized according to the understanding of water's role. Finally, the classic Pfitzinger reaction procedure was modified to yield the expected 2-substituted 7-fluoroquinoline-4-carboxylic acids. [ABSTRACT FROM AUTHOR]

Though previous studies have shown that the presence of water strongly influences wave responses of rock fractures, water effects on wave behaviours across clay-rich rock fractures have been ambiguous until now. In the present study, we conducted considerable ultrasonic measurements on single rock fractures filled with kaolinite-dominant gouges at varying water saturation degrees to investigate the water effects on elastic S-wave propagation and attenuation across clay-rich rock fractures. The experimental results reveal that the S-wave velocity across single clay-rich rock fractures slightly increases and decreases with the progressively increasing water saturation degree. An increase in water saturation leads to a concave trend of the spectral amplitudes, while it moderately affects the central frequency of transmitted S-waves. In addition, the seismic quality factor across single clay-rich rock fractures follows an exponential growth trend with the water saturation, suggesting the exponentially negative relation between S-wave attenuation and the water saturation. We attribute the water saturation-dependent S-wave attributes across single clay-rich rock fractures to the combined effects of the local flow and the degradation of grain contacts. Compared to P-wave, S-wave exhibits less sensitivity to varying water saturation of clay-rich rock fracture. Upon increasing water saturation, S-waves display similar velocity and central frequency trends with P-waves. The tendencies of spectral amplitude and seismic quality factor for S-waves are approximately opposite to those for P-waves as the water saturation degree increases. We interpret these discrepancies by the fact that S-wave attributes across single water-saturated clay-rich rock fractures mainly depend on the properties of the skeletal frame, while the characteristics of the particles, pore fluid, and skeleton frame dominate P-wave behaviours. The outcomes of the current work facilitate our understanding of the fluid effects on the interaction of waves with clay-rich rock discontinuities. Highlights: S-wave velocity and peak spectral amplitude across single clay-rich rock fractures exhibit concave trends upon rising water saturation. The increased water saturation modestly affects the central frequency of S-wave propagating across single clay-rich rock fractures. The seismic quality factor for S-waves exponentially grows with the water saturation degree of clay-rich rock fractures. The higher the S-wave frequency, the higher the wave velocity, the less the wave energy transmission, and the more the wave dissipation. The water-induced evolution of peak spectral amplitude and seismic quality factor for S-waves is roughly opposite to that for P-waves. [ABSTRACT FROM AUTHOR]

The coupling effect of moisture content and temperature on the elastic modulus of concrete is experimentally investigated. The elastic modulus of dry concrete exhibits a clear temperature-weakening effect, while the elastic modulus of wet concrete exhibits a water-strengthening effect at room temperature. Under humidity-heat conditions, the elastic modulus of wet concrete declines with the temperature rise. When the temperature is 20 °C, 200 °C, 400 °C, 520 °C, and 620 °C, the humidity–heat coupling factors of the elastic modulus change rate D I ˙ F with moisture content are 0.08, 0.07, 0.04, 0.01, and −0.03, respectively, and the declining rate increases with the rise of moisture content. The relation between the humidity-heat coupling factor DIF, moisture content, and temperature was established; The equivalent relation between the water-strengthening effect and the temperature-weakening effect of the elastic modulus was obtained. The temperature range of the strengthening effect and "apparent weakening effect" of water stored inside concrete before heating on elastic modulus was determined; The evolutionary mechanism of the competition between the microcrack expansion and healing of concrete under combined humidity and heat conditions was revealed. [ABSTRACT FROM AUTHOR]

Water is often involved in many catalytic processes, which can strongly affect structural evolution of catalysts during pretreatments and catalytic reactions. In this work, we demonstrate a promotional effect of H2O on both oxidative dispersion and spontaneous aggregation of Ag nanocatalysts supported on alumina. Ag nanoparticles supported on γ-Al2O3 and Ag nanowires on Al2O3(0001) can be dispersed into nanoclusters via annealing in O2 above 300 °C, which is accelerated by introduction of H2O into the oxidative atmosphere. Furthermore, the formed highly dispersed Ag nanoclusters are subject to spontaneous aggregation in humid atmosphere at room temperature. Ex situ and in situ characterizations in both powder and model catalysts suggest that formation of abundant surface hydroxyls and/or water adlayer on the Al2O3 surface in the H2O-containing atmosphere facilitates the surface migration of Ag species, thus promoting both dispersion and aggregation processes. The aggregation of the supported Ag nanostructures induced by the humid oxidative atmosphere enhances CO oxidation but inhibits selective catalytic reduction of NO with C3H6. This work illustrates the critical role of H2O in structure and catalytic performance of metal nanocatalysts, which can be widely present in heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

Water is a crucial factor that influences the mechanical behavior of rock and can induce failure. The aim of this study was to investigate the effects of water content and water distribution on the mechanical behavior of sandstone subjected to triaxial compression. Sandstone samples under different water states, including dry, unsaturated, saturated, and long-term saturated, were prepared. Some saturated samples were dried in air for different periods to prepare samples that were dry on the outside but remained wet on the inside. The triaxial compression tests were performed on the samples under four confining pressures: 5, 10, 15 and 25 MPa. The results indicated that the water state of a sandstone sample can be characterized by its water content, soaking time, water distribution, and long-term saturation. The different water states can affect remarkably the strength, deformation, and failure pattern of the sandstone samples subjected to triaxial compression. Several empirical equations were established to describe the evolution of the mechanical behavior of sandstone with increasing water content and soaking duration. The nonuniform distribution of water promotes the generation of tensile cracks, while increasing confining pressure promotes the development of shear cracks. The strength of sandstone samples with dry outside and wet inside are lower than that of samples with wet outside and dry inside. What is more, a long-term saturated state increases the strain-softening of the sandstone samples, thereby increasing their deformation and lowering their strength. Highlights: Influence of water state including water content and water distribution on sandstone is comprehensively investigated by triaxial experiments. A series of predictive empirical equations are established to describe the evolutions of the mechanical properties of sandstone with water content/soaking duration. The strengths of the sandstone samples in the dry outside but wet inside state are smaller than those of samples in the wet outside but dry inside state. A long-term saturated state increases the softening of the rock, thereby increasing the deformation and lowering the strength. Water especially nonuniformly distributed water promotes the propagation of tensile cracks near the surface of the rock. [ABSTRACT FROM AUTHOR]

Electrochemical deposition of lanthanides and their alloys can be implemented at room temperature from organic ionic media, such as ionic liquids (ILs). In this work, we studied Sm and Co electrodeposition and their codeposition in the [BMP][DCA] (1-butyl-1-methylpyrrolidinium) IL with controlled water content by electrochemical methods combined with scanning probe microscopy and X-ray analysis of the formed deposits. It is shown that both Co and Sm can be deposited electrochemically from the corresponding single–component solutions in the chosen IL and their deposition potential shifts positively at an increase in the water concentration (deposition acceleration). Sm–Co codeposition is observed in an IL solution containing ions of the both metals (Sm(III) and Co(II)). Here, Sm is codeposited at much less negative potentials (by 0.42 V) than those of Sm deposition from an IL solution containing only Sm(III) ions. An increase in the water concentration in the solution, however, results in inhibition of Sm–Co codeposition. We relate the inhibition of Sm–Co codeposition in the presence of water to formation of an oxide film on the deposit surface, which hinders further reduction of Co ions and therefore codeposition of Sm–Co. [ABSTRACT FROM AUTHOR]

[Display omitted] • Peroxyoxalate chemiluminescence in aqueous medium is several orders of magnitude less efficient than in anhydrous aprotic organic solvents. • However, water addition of up to 0.7 mol/L to an aprotic organic medium results in a significant increase of singlet excitation quantum yields. • Contrarily, higher water concentrations result in a drastic quantum yield decrease, which is not only due to oxalic ester hydrolysis. • Photophysical studies with several chemiluminescence activators confirm the mechanism of the chemiexcitation step in partially aqueous media. Chemiluminescence transformations are widely utilized in analytical and bioanalytical applications. Specifically, the peroxyoxalate system can be employed for sensitive quantification of a wide variety of analytes. Under anhydrous conditions, the peroxyoxalate reaction shows extremely high emission quantum yields, comparable to highly efficient bioluminescence systems. However, in aqueous media, important for bioanalytical applications, the emission efficiency suffers a significant decrease of several orders of magnitudes, although the reason for this loss in efficiency is unknown up to now. In the present work, we show the results of a detailed photophysical study on the effect of water on the chemiexcitation efficiency of the peroxyoxalate reaction using bis(2,4-dinitrophenyl) oxalate as reagent and imidazole as base catalyst in the presence of different chemiluminescence activators. It is shown that in 1,2-dimethoxyethane/water mixtures (DME:H 2 O), singlet quantum yields increase with increasing the water concentrations up to 0.7 mol/L, followed by a steady decrease at higher water concentrations. The decrease in quantum yields is not predominantly due to concurrent ester hydrolysis, as quantum yields could be corrected for this side reaction. This indicates that the quantum yield decrease is due to the diminished chemiexcitation efficiency in the presence of water. Using different activators, it is shown that chemiexcitation occurs via electron transfer and electron back-transfer steps between a high-energy intermediate and the activator. Additionally, its efficiency is governed by the energetics of the electron back-transfer step, in agreement with the Chemically Initiated Electron Exchange Luminescence (CIEEL) mechanism, also in partially aqueous environment. Lower excitation efficiency in aqueous media may be due to formation of solvent-separated radical ion pairs, inhibiting chemiexcitation. [ABSTRACT FROM AUTHOR]

• Stabiliser depletion was studied in a DB propellant. • Rate of stabiliser depletion increases with increasing water content. • Water promotes the autocatalysis decomposition mechanism of cellulose nitrate above 70 °C. • A modified Arrhenius equation is proposed to model the influence of water on the stability of DB propellant. Numerous studies have been conducted on the decomposition mechanisms of cellulose nitrate (NC), a polymer employed in double base (DB) rocket propellants. It is well known that storage temperature affects the lifetime of these energetic formulations. However, less studies have been published on the influence of water. This research examined the role of water on the stabiliser consumption rate during accelerated ageing of a DB rocket propellant, as well as the impact on the shelf life prediction of the energetic formulation. Different volumes of water (0.8, 1.6, 2 and 4 µl/g) were added to the propellant in sealed vials, which were then isothermally aged (70, 80, 90, 100 °C). Analyses of the stabiliser consumption showed a faster decomposition kinetics in presence of water which is indirectly linked to the shortening of the storage life of the NC based propellant by 35 %. For the conditions, an activation energy of 133 ± 4 kJ/mol was reported for the water catalytic decomposition mechanism. A numerical model that included water as a variable was reported to reduce the uncertainty in the determination of the service life of NC based propellant. International standards such as Allied Ordnance Publication 48 should not overlook the effect of water/moisture on the safety of ammunition containing NC and should implement a modified Arrhenius equation. [ABSTRACT FROM AUTHOR]

• Osiris Temple wasn't rescued during UNESCO saving campaign of Aswan temples. • Yellowish and pinkish sandstones are the building materials of the temple. • Fluctuations of Nile water level decayed the temple building materials severely. • Main intrinsic decay factors is the clayed matrix of sandstones. The ancient Osiris Temple at Philae/Aswan, also known as Abaton, was considered one of the most sacred and mysterious temples in Egypt. In 1960, UNESCO rescued Philae temples because the rise of the water level after the construction of the Old and New Dam of Aswan caused the submergence of all temples underwater. Rescue camping was performed to protect all Aswan temples. Unfortunately, Osiris Temple was not rescued and was forgotten in its original place on Bigeh Island. Currently, this temple is subjected to Nile water effects and is partially submerged underwater due to Nile water level changes. This study aims to unravel and assess the conservation state of the temple sandstone-building material through multianalytical and examination techniques (X-ray diffraction, X-ray fluorescence, Raman spectroscopy, polarizing microscopy, binocular microscopy, and scanning electron microscopy). Furthermore, in situ records were obtained, and degradation maps were drawn to establish the patterns of damage and decay of the building material of the Osiris temple. The results showed that blackening, soiling, and disintegration are the dominant decay patterns in the building material of the temple. In addition, the Nile water as an extrinsic factor severely affected the conservation state of the temple due to the continuous exposure to water force. The mineralogical composition of sandstone played an important role in its degradation as an intrinsic decay factor due to mainly dispersion of clayed and/or carbonate matrix dissolution, quartz hydrolysis, and feldspar alteration. [Display omitted] [ABSTRACT FROM AUTHOR]

National highway projects present a crucial role in economic growth, as they have a great influence on the national income. Therefore, the decision makers plan to construct these projects at a rapid rate. To achieve the just aforesaid, the utilization of asphalt of adequate quality and gradation is essential. The key problem which lies in recent decades is that many types of asphalt mixtures are rejected and reconstructed in the site due to the gradation variation of aggregates in the asphalt mixture which waste raw materials, cost and time. Thus, this research seeks to assess the possibility of accepting asphalt mixes with aggregates gradation variation (within the range from +4% above the upper specification limit to −2% below the lower specification limit). A wearing surface mix with gradation 3B was prepared according to the Egyptian code. The gradation variation was presented as the aggregate gradation is out of the specification limits during Hot Mix Asphalt (HMA) production. The aggregate gradations lie above and below the upper and lower specification limits, respectively, by ±2%, ±4% and ±6%. The design gradation of the control mix was included as a reference case. The different mix properties were measured using the Marshall Mix design method. Then, the performance of HMA mixes was evaluated under the effects of high temperature and water cycles through applying wheel loading tracking and Indirect Tensile Strength (ITS) tests. The results show that the 3B mixes with a gradation within a range of +4% to −2% of the upper and lower specification limits recorded the lowest rutting depth and the highest water damage resistance in hot regions compared to ordinary asphalt mixes. In summary, the new aggregate gradation limits will provide a reference for the design of asphalt mixture in hot climate regions. [ABSTRACT FROM AUTHOR]

Understanding the water-involved mechanism on metal oxide surface and the dynamic interaction of water with active sites is crucial in solving water poisoning in catalytic reactions. Herein, this work solves this problem by designing the water-promoted function of metal oxides in the ethanol oxidation reaction. In situ multimodal spectroscopies unveil that the competitive adsorption of water-dissociated *OH species with O 2 at Sn active sites results in water poisoning and the sluggish proton transfer in CoO-SnO 2 imparts water-resistant effect. Carbon material as electron donor and proton transport channel optimizes the Co active sites and expedites the reverse hydrogen spillover from CoO to SnO 2 . The water-promoted function arises from spillover protons facilitating O 2 activation on the SnO 2 surface, leading to crucial *OOH intermediate formation for catalyzing C-H and C-C cleavage. Consequently, the tailored CoO-C-SnO 2 showcases a remarkable 60-fold enhancement in ethanol oxidation reaction compared to bare SnO 2 under high-humidity conditions., (© 2024 The Author(s). Advanced Materials published by Wiley‐VCH GmbH.)

Considering water vapor is a component in almost all CO2-rich industrial gas streams, it is of critical importance to understand interaction mechanisms between adsorbent and adsorbate. This paper aims to comprehensively analyze water effect on CO2 adsorption for metal-organic framework (MOF) in a broad working pressure range which may bring some new insights based on a molecular simulation. First, Mg-MOF-74 is selected and synthesized according to previous literature. Equilibrium adsorption capacity and enthalpy are obtained by grand canonical Monte Carlo simulation, and the results for high-pressure CO2 adsorption are validated through magnetic suspension balance experiment. It is indicated that there are three adsorption stages for pure CO2 and four adsorption stages for pure H2O under different pressure. Adsorption enthalpy also varies with adsorption capacity, which is fully explained from the angle of adsorption stages and energies. Further simulation of flue gas (CO2/H2O/N2) adsorption at different humidity are carried out, and selectivity between CO2 and H2O is analyzed. At 298 K, 100 kPa, with 3% water content, CO2/H2O selectivity is 5.6 × 10−5. When temperature rises to 388 K, CO2/H2O selectivity rises to 6.2 × 10−3. Adsorption density distributions, simulation snapshots, and radial distribution functions are used in analysis processes, which could provide a general perspective for analyzing CO2 adsorbents in the presence of H2O.

The coupling effect of moisture content and temperature on the elastic modulus of concrete is experimentally investigated. The elastic modulus of dry concrete exhibits a clear temperature-weakening effect, while the elastic modulus of wet concrete exhibits a water-strengthening effect at room temperature. Under humidity-heat conditions, the elastic modulus of wet concrete declines with the temperature rise. When the temperature is 20 °C, 200 °C, 400 °C, 520 °C, and 620 °C, the humidity–heat coupling factors of the elastic modulus change rate DI˙F with moisture content are 0.08, 0.07, 0.04, 0.01, and −0.03, respectively, and the declining rate increases with the rise of moisture content. The relation between the humidity-heat coupling factor DIF, moisture content, and temperature was established; The equivalent relation between the water-strengthening effect and the temperature-weakening effect of the elastic modulus was obtained. The temperature range of the strengthening effect and “apparent weakening effect” of water stored inside concrete before heating on elastic modulus was determined; The evolutionary mechanism of the competition between the microcrack expansion and healing of concrete under combined humidity and heat conditions was revealed.

During tunnel excavations through shale formations in central and southwest China, engineering problems, such as large deformations and distorted arches, were encountered due to radial stress unloading and groundwater pressure. Few studies have been carried out on the issues exhibited by soft shale tunnels that have considered the comprehensive influence of unloading and water effects. To characterize the unloading behaviors, a series of conventional triaxial compression (CTC) tests and unloading confining pressure (UCP) tests were performed under drained conditions and compared. Based on theoretical and experimental analyses, deformation parameters from the UCP process were derived and compared with those from the CTC test. The stress–strain response, evolution of deformation and strength parameters, and postpeak mechanical behavior and failure modes were analyzed in order to reveal the unloading and water effects. To quantify the difference between the CTC and UCP behaviors in geotechnical practice, a tunnel excavation was simulated using the CTC and UCP models. The distributions of damage and displacement were analyzed in a numerical case study. The results showed the comprehensive dependency of shale behaviors on unloading and water effects. The numerical case revealed significant tunnel deformation and fewer plastic zones in the excavation when using the UCP model rather than the CTC model. To accurately simulate the deformation and damage distribution, this study provided a methodology for construction design using the UCP test and the model for unloading and water-affected geotechnical engineering. [ABSTRACT FROM AUTHOR]

[Display omitted] • FTIR spectroscopy of adsorbed CO on impregnated and ion exchanged Pd/SSZ-13 samples. • CO reducing effect on Pd2+ only in the presence of H 2 O. • H 2 O compensates with H+ the zeolite exchange sites set free by Pd reduction. • H 2 O mobilizes isolated Pd cations, making possible the reduction reactions. • Combined effect of H 2 O and CO allow to detail the assignments of carbonyl IR bands. Pd speciation induced by the combined effect of CO and water on Pd/SSZ-13 samples prepared by both impregnation and ion exchange was examined by FT-IR spectroscopy of CO adsorbed at room temperature and at liquid nitrogen temperature on anhydrous and hydrated samples. Starting from the literature findings related to the CO reducing effect on Pd cations, the present work gives precise spectroscopic evidences on how water is necessary in this process not only for compensating with H+ the zeolite exchange sites set free by Pd reduction, but also for mobilizing isolated Pd2+/Pd+ cations and making possible the reduction reactions. The aggregation of some Pd+ sites, just formed by the reduction and mobilized by the hydration, gives rise to the formation of Pd 2 O particles. Also, Pd0(1 0 0) sites are observed with CO on hydrated sample, formed by the aggregation and reduction of isolated Pd cations. Moreover, Pd0(1 1 1) sites are formed on the surface of PdO x particles during CO outgassing. The observation of the combined effect of water and CO allowed to define assignments of IR bands related to carbonyls of Pd in different oxidation states and coordination degrees. [ABSTRACT FROM AUTHOR]

As-synthesized [Cu 2 (μ-O)]2+-ZSM-5 catalyst shows excellent selectivity to methanol in C1 oxygenates for mild methane oxidation with H 2 O 2 solution, and the reaction mechanism and role of H 2 O and chloride are deeply investigated both experimentally and theoretically. [Display omitted] • A new [Cu 2 (μ-O)]2+-ZSM-5 catalyst was applied for selective mild oxidation of CH 4 to methanol in H 2 O 2 solution. • The reaction mechanism was deeply elucidated both experimentally and theoretically. • Methanol formation via direct dissociation of *CH 3 OOH rather than OH. • The crucial role of water and chloride is intensively investigated. Controllable methane oxidation to methanol is a challenging in catalysis, usually suffering from over-oxidation. We report that a single-metal [Cu 2 (μ-O)]2+-ZSM-5 catalyst can activate methane to methanol with superior high selectivity up to 91.3% in C1 oxygenates and 12.31 mol methanol kg cat -1h−1 by avoiding over-oxidation. Density functional theory (DFT) calculations combined with in situ FT-IR and EPR demonstrated that methanol forms via direct dissociation of strongly adsorbed *CH 3 OOH generated by *CH 3 spontaneously reacting with H 2 O 2 rather than OH. It was found that water plays a crucial role in enhancing methanol formation as other solvents ethanol and acetone show negligible activity. DFT calculations and TPD results confirmed that adsorbed H 2 O* facilitates active site regeneration and accelerate methanol desorption via H migration between H 2 O* and [Cu 2 (μ-OH) 2 ]2+. In addition, the introduction of chloride is favorable for the formation of active [Cu 2 (μ-O)]2+ species owing to a decrease in binding energy between active sites and ZSM-5, and can promote methanol production by weakening the interaction between methanol and active sites by accepting electron from Cu. [ABSTRACT FROM AUTHOR]

Architectural heritage is deeply threatened by extreme weather events due to ongoing climatic change. Since these phenomena are becoming more and more serious, their effects cannot be neglected when a reliable assessment of a historic masonry structure is required. In this paper, the phenomenon of rising damp was studied, focusing on the influence of water on the unit weight of masonry walls made from fired clay bricks and lime mortar. This study consists of a basic experimental research on the variations in the unit weight of masonry undergoing an ageing treatment, which was simulated through some cycles of capillary water absorption and temperature changes. The experimental study proves that penetrating damp causes an increase in masonry unit weight of more than 20%. This basic result is significant in the structural assessment of historic masonry buildings. Subsequent papers will analyze the interaction with strengths parameters.

A comparative spectral study of the complex formation of molecules of nitro-substituted indoline spiropyrans with metal ions in acetonitrile and water–acetonitrile solutions, and also in acid-containing acetonitrile, was carried out. It was shown that metal complexes are not formed in the presence of water, due to protonation of photochromic spiropyran molecules. Spectral and photochromic properties of the protonated complexes obtained in the presence of water differ from those of protonated complexes arising upon interaction with an acid. A photochromic method for detecting metal ions in aqueous solutions was proposed. [ABSTRACT FROM AUTHOR]

In the Lean NO x Trap (LNT) technology, ammonia (NH 3) occurs as reaction intermediate in conversion of trapped nitrogen oxides (NO x) to nitrogen gas (N 2) using hydrogen gas (H 2) reductant. The use of an LNT for synthesizing NH 3 from NO x is potentially an attractive option for small-scale green NH 3 production by converting locally produced NO x pollutant to an important chemical. In this work, it is investigated to what extent the product selectivity towards NH 3 on the standard model catalyst Pt/BaO/Al 2 O 3 can be maximized depending on reaction conditions for trapping and reducing NO x with H 2 in the temperature range of 75–200 °C. The LNT catalyst preparation was varied by using Pt, Pd and bimetallic combinations, as well as different support materials, namely Al 2 O 3 , TiO 2 , ZrO 2 and MgO. NO x adsorption and selectivity of captured NO x reduction to ammonia is discussed in terms of texture and the chemical nature of the support. The NH 3 selectivity is influenced by the water vapor content in the gas feed. Storage of NO x in absence of water followed by reduction with hydrogen gas in presence of water vapor was found to be the most favorable operation mode of the LNT for NH 3 formation. The NH 3 selectivity reached 82% at 150 °C. Explanations for the role of water and in this catalytic chemistry are offered and its consequences for catalyst preparation are discussed. The optimum water content of the reacting gases is predicted to be strongly dependent on catalyst preparation. [Display omitted] • NH 3 formation is strongly affected by noble metal and catalyst support formulation. • Dry NO x storage followed by wet reduction phase is best scenario for NH 3 formation. • Pt/BaO/Al 2 O 3 can achieve NH 3 formation with 82% selectivity. • Water vapor content for optimum NH 3 formation performance of Pt/BaO/Al 2 O 3 is 1.5%. [ABSTRACT FROM AUTHOR]

The effects of water content on physicochemical properties such as density, dynamic viscosity, and electrical conductivity of HHexen(Tf2N), composed of monoprotic N-hexylethylenediaminium as cation and bis(trifluoromethylsulfonyl) imide as anion, were studied in the temperature range T = 303.15–353.15 K. HHexen(Tf2N) was dissolved a small amount of water (up to 6.53 wt%, corresponding to w0 = [H2O]/[PIL] = 1.65) as it is a hydrophobic protic ionic liquid (PIL). The physicochemical properties of HHexen(Tf2N) were significantly influenced by its water content. The temperature dependence of the physicochemical properties at different water contents (0.50 wt%, 0.95%, 1.93%, 3.02%, 4.03%, 5.14% and 5.95%, corresponding to w0 = 0.12, 0.23, 0.47, 0.74, 1.0, 1.28 and 1.50, respectively) were studied. With an increase in the water content, the density and dynamic viscosity decreases while the electric conductivity increases in a given temperature range. The Walden lines of HHexen(Tf2N) show a good ionic character as the curves are all located in the range of ΔW = 0.5 ± 0.2 (ΔW = log101/η −log10Λ) at different water contents. The ionicity shows an increasing trend with an increase of water content; this is evident when the water content rises to approximately 4.0% (w0 = 1.0). Additionally, HHexen(Tf2N) was used to extract Co(II) ions from an aqueous solution. Inductive coupled plasma emission spectrometry results showed that more than 99.5 wt% of Co(II) ions moved from the 100 mmol·kg−1 aqueous layer to the HHexen(Tf2N) layer (of equal volume). After extraction of the Co(II) ions, the PIL layer contained 7.90% of water (w0 = 2.0). [ABSTRACT FROM AUTHOR]

In this paper, a series of experiments were conducted on typical volcanic breccia collected from the foundation of Baihetan Dam. Considering previous work, the mechanical behavior and permeability of the volcanic breccia were further investigated. The experimental results showed that the compressive strength and Young's modulus of the volcanic breccia decrease due to the presence of water. However, the Poisson's ratio of the wet specimens was higher than that of the dried specimens. The permeability evolution under triaxial compression was divided into 5 stages. The fluid pressure showed a great influence on the permeability of the volcanic breccia. The water weakening mechanism and the effect of fluid pressure on the permeability were discussed. The effect of water on the strength of volcanic breccia is influenced by both subcritical crack growth and calcite dissolution. Due to the pore pressure gradient and the water weakening effect, the change in permeability with volumetric strain varies greatly. [ABSTRACT FROM AUTHOR]

For Fangshan granite in Beijing, the static compression and dynamic compression tests have been carried out separately under natural air drying and water saturation. It was found that the dynamic compressive strength of water-saturated granite is higher than that of air-dried granite, which is contrary to the result that the strength of water-saturated rock is lower than that of air-dried granite under static load. Furthermore, under the medium strain rate condition, when the strain rate is 85 s−1, the dynamic strength of natural air-dried granite could be increased by nearly 0.5 times compared with its static state. The dynamic strength of water-saturated granite could be increased by nearly 1–2 times compared with its static strength, which shows that water-saturated granite has stronger strain rate sensitivity than natural air-dried granite. Meanwhile, under impact loading, from the perspective of water-bearing granite the Bernoulli effect of fluid, the adhesion effect of free water and the Stefan effect of fluid in water-saturated granite were revealed, and found to be the essential reasons affecting the dynamic strength of water-saturated granite. The dynamic strength in different water-bearing states in the range of medium strain rate could then be analyzed in depth, providing a certain reference value for the strength design of water-bearing rock engineering.

Catalysts are very important in controlling the pollutant emissions and are used for hundreds of chemical processes. Currently, noble metal-based catalysts are being replaced for other kinds of materials. In this study, three lanthanum-based perovskite-like oxides were synthesized (LaCo, LaCoMn, and LaMn) by the glycine-combustion method. The powder catalysts obtained were supported onto cordierite ceramic monoliths using an optimized washcoating methodology to obtain the subsequent monolithic catalysts (LaCo-S, LaCoMn-S, and LaMn-S). Sample characterization confirmed the formation of the perovskite-like phase in the powder materials as well as the presence of the perovskite phase after supporting it onto the monolithic structure. The XPS analysis showed a general decrease in lattice oxygen species for monolithic catalysts, mainly caused by the colloidal silica used as a binder agent during the washcoating process. Additionally, some variations in the oxidation state distribution for elements in Co-containing systems suggest a stronger interaction between cordierite and such catalysts. The catalytic activity results indicated that powder and monolithic catalysts were active for single-component VOC oxidation in the following order: 2-propanol > n-hexane ≅ mixture > toluene, and there was no evidence of loss of catalytic activity after supporting the catalysts. However, LaMn-S had a better catalytic performance for all VOC tested under dry conditions, achieving oxidation temperatures between 230–420 °C. The oxidation efficiency for the VOC mixture was strongly affected by the presence of moisture linking the oxidation efficiency at wet conditions to the VOC chemical nature. Additionally, for higher VOC concentrations, the catalyst efficiency decreased due to the limited number of active sites.

The variation of elastic and electromechanical properties of microtubes of diphenylalanine dipeptide as a function of the degree of filing of nanochannels by water molecules is reported in this paper. Quantum chemical calculations reveal different contributions of water layers in the microtubes to Young's modulus and the effective piezoelectric coefficient. The application of diphenylalanine microtubes in micro-electromechanical systems is also discussed. [ABSTRACT FROM AUTHOR]

Humic acid (HA) and water play an important role in polycyclic aromatic hydrocarbons (PAHs) adsorption and biodegradation in soil. In this work, molecular dynamics (MD) and electrostatic potential surfaces (EPSs) simulations are conducted to research the contribution of quartz surface, leonardite humic acid (LHA), and water to PAH adsorption. The adsorption energies between PAHs and LHA are much higher than that between PAHs and quartz. Simulation shows that the hydroxyl and carboxyl groups' attraction by LHA is the main adsorption force between PAHs and LHA. The π-π interaction between PAHs and LHA also contributes to the adsorption process. In addition, the mobility of water on quartz surface is much higher than that of LHA. Water should be regarded as an adsorbate in the system as well as PAHs. However, the presence of water has a remarkable negative effect on the adsorption of PAHs on LHA and quartz. The bridging effect of water could only enhance the stability of the aggregation system. The adsorption contribution of quartz and LHA to PAHs in the soil model tends to 0 if the water layer reaches 2.0 nm. [ABSTRACT FROM AUTHOR]

The available methods for accelerated ageing simulation in laboratory of compacted bituminous mixtures are often not representative of the ageing mechanisms experienced in the field. The objective of this study was to develop an alternative ageing method, Tecnico accelerated ageing (TEAGE). The method is intended to simulate the ageing of bituminous mixtures under specific environmental conditions by applying watering/drying cycles and ultra-violet (UV) radiation in equivalent levels to those observed in the field during a certain time. In this study a type of mixture was aged using TEAGE and LTOA (long-term oven ageing) methods and then tested for mechanical performance conducting stiffness, fatigue resistance and indirect tensile strength tests. Additionally, the chemical composition of the water used for the watering/drying cycles was analysed and recovered binders were tested for softening point and penetration. TEAGE-aged specimens showed clear evidence of an ageing gradient through the specimens' depth, substantial reduction in fatigue life (15% reduction in Ԑ6) and a visible effect on the colouration of the UV exposed surface when compared with LTOA-aged specimens. The overall results and comparison with other studies indicate that TEAGE framework addressed in a more consistent way the ageing mechanisms that could be seen in the field. [ABSTRACT FROM AUTHOR]

A comprehensive investigation of the roles of water catalysts on O3 with HNO in the troposphere has been carried out by quantum chemical calculations at the CCSD(T)/aug-cc-pVTZ//M06-2X/6-311++G(2d,2p) levels of theory. Besides, the AIMD (ab initio Molecular Dynamics) simulation also used to help us to understand the mechanism of this reaction. The results show that the HNO + O3 reaction undergoes a channel for the formation of NO + HO3 and overcomes the energy barrier of 1.60 kcal·mol−1. After adding water molecules, the obtained product did not change, but the potential energy surface was much more complicated than the bare reaction, and it went through four reaction channels of HNO···H2O + O3, H2O···HNO + O3, H2O···O3 + HNO and O3···H2O + HNO. Among them, the channel HNO···H2O + O3 is the dominant channel for water molecules to participate in the reaction. Overall, these results show how water catalyzed the gas-phase reactions under atmospheric conditions. [ABSTRACT FROM AUTHOR]

• Adding 0.1 mol% H 2 O in the feed increases CH 3 OH formation rate by 20% over In 2 O 3 /ZrO 2. • H 2 O-induced oxygen vacancies improve CO 2 adsorption capacity. • DFT reveals the correlation of InOOH and CH 3 OH formation with H 2 O addition. • Excess H 2 O leads to aggregation of catalyst and negatively affects H 2 dissociation. • Excess H 2 O causes surface variations of InOOH species and oxygen vacancies. CO 2 hydrogenation with renewable energy is one of the promising approaches to mitigate CO 2 emissions and produce sustainable chemicals and fuels. The effect of adding H 2 O in the feed gas on the activity and selectivity of In 2 O 3 /ZrO 2 catalysts for CO 2 hydrogenation to methanol was studied using combined experimentatal and computational efforts. Notably, adding an appropriate amount of H 2 O (0.1 mol%) in the feed gas significantly enhanced the CH 3 OH formation (ca. 20%) with improved selectivity. Characterization with STEM/EDS and CO 2 -TPD confirmed the preservation of In-Zr strong interaction in the presence of additional H 2 O and H 2 O-induced oxygen vacancies, which significantly improved CO 2 adsorption capacity. XPS analysis revealed the formation of InOOH species due to H 2 O addition, which appeared to correlate to H 2 O-dependant enhancement of CH 3 OH formation. Density functional theory calculations rationalized the effect of surface H 2 O on InOOH formation and its correlation to CH 3 OH synthesis activity. Adding H 2 O was found to facilitate surface InOOH formation, suppress CO formation through COOH* intermediate, and promote CH 3 OH formation via HCOO* intermediate. However, excess H 2 O addition resulted in aggregation of In species and reduction of surface In0 for H 2 dissociation. [ABSTRACT FROM AUTHOR]

The static anisotropic elastic properties of shales can be measured by performing uniaxial compression on core specimens with bedding planes of different inclination angles (or anisotropy angles). However, these measurements differ when different numbers of specimens are tested, mainly because of the heterogeneity of shales. This study aimed to quantify the uncertainties of the anisotropic elastic properties of a shale when testing different numbers of specimens with distinct anisotropic angles. Three sets of room-dried core samples were prepared, and each set consisted of seven specimens with incremental anisotropic angles of 15°. Uniaxial compression measurements were used to determine the anisotropic elastic properties for a given number (2–7) of specimens in each set. The results indicated that the uncertainties of the determined anisotropic elastic properties decreased monotonically as the number of measurements was increased. The results also suggested that at least five specimens with different anisotropic angles should be tested in order to obtain accurate elastic properties (uncertainty <10%). An additional set of wet specimens of the same shale were also tested and analyzed. It was found that water absorption significantly decreased Young's moduli, increased Poisson's ratios, and had a limited effect on the shear modulus. The wet specimens also displayed a slightly stronger anisotropic ratio of the elastic moduli compared to the room-dried specimens. Finally, the alteration of the anisotropic elastic properties of shales upon water absorption was tentatively related to the mineralogy and microstructure heterogeneity. The findings of this study have major implications for many geoengineering operations where the anisotropic elastic properties of shales must be considered. [ABSTRACT FROM AUTHOR]

• The preparation of the new ethalineF DES (1:2 ChF:EG). • EthalineF shows two peaks in 19F NMR spectra. • The spin nature of fluorine atom permits us to measure its self-diffusion coefficient. • NMR-predicted conductivities were calculated and used to assist the ion dissociation in ethalineF which we found not fully dissociated. • Adding water provides more fluidity and enhances the conductivity. Due to their favorable physical properties, deep eutectic solvents (DESs) have been of interest in many applications in the energy and industry sectors. In this study, we investigate the new deep eutectic solvent ethalineF (a 1:2 M ratio of choline fluoride:ethylene glycol) and the effect of water addition on the solvation dynamics compared to the better known ethaline (a 1:2 M ratio of choline chloride:ethylene glycol). Femtosecond transient absorption spectroscopy and NMR diffusometry were used to study the solvation dynamics. 19F NMR spectra were obtained for ethalineF solutions with different water additions. The 19F NMR spectra show two fluorine signals; one can be assigned to fluoride anions solvated by EG and the other signal to fluoride anions associated with the much heavier and less mobile choline cation. Density, viscosity, conductivity, and E T (30) polarity measurements are also provided for ethalineF. The nuclear spin nature of fluorine atom permits to measure the self-diffusion coefficient of the negative ion in addition of the cation diffusion in a choline halide based deep eutectic solvent system. This allows to calculate the NMR-predicted conductivities σ NMR. The obtained ion dissociation coefficients α D at different water concentrations suggest a partial ion dissociation which was commensurate with the relatively low ion conductivity. The observed modest conductivity of ethalineF is explained in terms of ion association as well as the gradual increase in conductivity caused by the addition of water. [ABSTRACT FROM AUTHOR]

Selective catalytic reduction (SCR) is currently the main method for removing nitrogen oxides (NO x) from mobile sources. SCR catalysts are susceptible to the toxic effects of H 2 O in the actual flue gas. There is still a need to develop SCR catalysts with better activity and water resistance. A large number of existing studies have shown that the effect of H 2 O on the performance of SCR catalysts mainly depends on the type of reductant used in the SCR reaction, the reaction conditions and the catalyst type. This review summarized the mechanism of the promoting or inhibiting effect of H 2 O in the SCR reaction process in detail. The ways in which reaction conditions such as water content and reaction temperature affect different SCR reactions as well as SCR catalysts were discussed. Finally, current improvement strategies to enhance the catalytic activity and water resistance of SCR catalysts were collated. This work helps researchers to gain a deeper understanding of the mechanism of water's role in SCR reactions. It provides theoretical and methodological support for the preparation of SCR catalysts with higher water resistance. • The development of mechanisms of promotion and inhibition by H 2 O for selective catalytic reduction catalysts is listed. • The Mechanisms of promotion and inhibition by H 2 O for selective catalytic reduction denitrification are discussed. • Optimization applications in diesel engine are investigated. • Improvement suggestions for performance enhancement of SCR are proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • The performance of Mn-Na 2 WO 4 /SiO 2 catalysts in CL-OCM can be significantly improved by cofed water. • Water does not alter the scheme of product formation but influences their kinetics. • Water facilitates the releasability of lattice oxygen. • The role of MnO x and Na 2 WO 4 is shown by in situ XRD and UV–vis spectroscopy. The oxidative coupling of methane (OCM) to C 2 H 6 and C 2 H 4 (C 2 -hydrocarbons) is an industrially attractive reaction, which has not yet been commercialized. Apart from the low selectivity to C 2 -hydrocarbons at high degrees of CH 4 conversion, another substantial drawback is the necessity to use pure O 2 when this oxidant and methane are cofed. Original OCM studies used an approach called chemical looping OCM (CL-OCM) that consists of alternating feeding of methane and air for product formation and catalyst reoxidation, respectively. The developed catalysts, however, suffer from their low ability to provide lattice oxygen for the desired reaction. Herein, we demonstrate that this catalyst property can be significantly improved when performing CL-OCM over Mn-Na 2 WO 4 /SiO 2 catalysts in the presence of water. In comparison to water-free CL-OCM, both methane conversion and C 2 -hydrocarbons selectivity increase resulting in at least doubling of the yield of these products. The selectivity to ethylene of about 53 % was obtained at about 24 % CH 4 conversion. The total selectivity to C 2 -hydrocarbons was about 76 %. The analysis of selectivity-conversion relationships for C 2 H 4 , C 2 H 6 , CO and CO 2 proved that water does not alter their general formation pathways but influences the kinetics of their formation. In situ X-ray diffraction, in situ UV–vis spectroscopic, and temperature-programmed tests (H 2 -TPR and O 2 -TPD with or without cofed H 2 O) showed that Mn 2 O 3 acts as the oxygen carrier in CL-OCM. In-situ DRIFTS proved the presence of O 2 – and O 2 2–. They can interact with water yielding OH radicals that accelerate CH 4 conversion. [ABSTRACT FROM AUTHOR]

[Display omitted] • La electrodeposits can be obtained from a [BMP][DCA] solution at room temperature. • La(III) electroreduction is accelerated in the presence of Co(II), Fe(II), and Ni(II). • No promoting effect on La codeposition is found in the presence of Cu(I) and Sn(II). • Water addition accelerates La(III) electroreduction in La(III) solution in IL. • Moderate water additives inhibit La-Me (Me = Co, Fe, Ni) codeposition. Room-temperature electrochemical deposition of lanthanides and their alloys can be achieved employing organic ionic media, such as ionic liquids (ILs). Here, we study the electrochemical (co)deposition of La and Fe-group transition metals from solutions in 1-butyl-1-methyl-pyrrolidinium dicyanamide IL, [BMP][DCA], with controlled water content. We show that electroreduction of La(III) ions starts in the two-component solutions containing La(III) + Me(II) (Me = Co, Fe, or Ni) and no added water in the same potential interval as the electroreduction of respective Me(II). La is thus codeposited with the respective Fe-group metal, as evidenced by voltammetric, microscopic, and X-ray analyses, at considerably more positive potentials than in a solution containing only La(III) ions. Such a promoting effect is not observed in the presence of Cu(I) and Sn(II). Furthermore, the effect of water on the (co)deposition of La and Fe-group metals is systematically investigated. The La-Me (Me = Co, Fe, or Ni) codeposition is inhibited in the presence of moderate amounts of water (up to 0.32 M). At higher water contents, particularly ≥0.32 M H 2 O in the La(III) + Ni(II) solution, the electroreduction of La starts at more positive potentials than the deposition of Ni. This allows obtaining La-Ni deposits with a high La content. The XPS data indicate that La is present in the deposits in both metallic and oxidized states, even if deposition occurs in a solution with no added water. The results obtained in this study offer valuable insight into the electro(co)deposition of La from IL solutions and contribute to the progress of techniques for producing lanthanide-based functional coatings. [ABSTRACT FROM AUTHOR]

Determining the time since death of an individual from skeletal remains is a challenging stage. In determination of time since death, climate conditions, environmental factors, conditions such as whether the body was buried or not, and genetic and personal factors must be evaluated all together. With these factors changing and with the exposure duration growing longer, changes occur in the morphology of the bone might increase. In this study, as part of an investigation, bones which had been found in a water-well during an excavation work in Mardin was used. After 36 pieces of bone that belong to a human were analyzed, it was found that the bones had lost most of their weight and density, that they were considerably fragile, that their medulla was emptied, and that there were intense erosions on the surfaces of bony tissue. While under normal circumstances and under the condition that it was a buried body it would take at least 50 years for these changes to occur, considering that the bones remained in water for a very long time, the corrosion had to be much more than expected. With the DNA comparison, it was found that the bones belonged to people who were claimed to have been killed in the 90s. In this study, it was aimed to determine the time of death of remains which were reported to have stayed in contact with water, and to study the effect of the environmental circumstances in which the bodies are found on the bones. [Med-Science 2017; 6(1.000): 139-43]

An efficient stereoselective three-component reaction for the synthesis of functionalized spiro[4H-pyran-3,3′-oxindole] derivatives was realized through an organocatalyzed domino Knoevenagel/Michael/cyclization reaction using a cinchonidine-derived thiourea as the catalyst. Using water as the additive was found to improve the product ee values significantly. Under the optimized conditions, the reactions between isatins, malononitrile, and 1,3-dicarbonyl compounds yield the desired spirooxindole products in good yields (71–92%) and moderate to high ee values (up to 87% ee). [ABSTRACT FROM AUTHOR]

Understanding the effects of water on the mechanical properties of silica glass is important for many applications of silicate glasses. In this study, the effects of water on both elastic and plastic properties of pure silica glass are investigated. The introduction of molecular water leads to an increase of Young's modulus of silica glass at low water content, while hydroxyl exhibits an opposite effect. While hydroxyl groups decrease both strength and fracture toughness of the glass via destructing the silica network connectivity, molecular water undermines these properties by effectively driving the silica network to a "strained" configuration in absence of external stress. The water effect can be characterized in terms of the change of Si-O bond length and Si-O-Si bond angle. The plateau in the stress-strain curves of silica with the existence of molecular water in compact tension is associated with the Si-O bond breaking followed by formation of silanol groups. Moreover, the introduction of molecular water lowers the critical tensile stress where the plateau occurs. Image 1 [ABSTRACT FROM AUTHOR]

This paper attempts to determine how the cooling effect of copper alloy B14 varies with roughness, type of water and type of nozzle. Several experiments were performed on 5mmthick copper alloy B14 plates with different combinations of the said parameters. The plates with smooth and rough surfaces were heated up to the 520 °C. Either tap or distilled water was used as coolant with constant volumetric flow rate, 1.2 L/min. Two types of nozzle were tested, namely, spray nozzle (460.404) and full jet nozzle (544.400). The results of the cooling rate were analyzed on the 1D model. It is observed that distilled water led to a slightly faster cooling rate than tap water, due to oxidation on the copper alloy; rough surface caused fast heat transfer compared to the smooth surface; the domination of nucleate boiling regime was observed in the case of full jet nozzle, as compared to the case of to the spray nozzle, because the full jet nozzle can prevent vapor formation on the material; the spray nozzle covered a larger wetting front area than the full jet nozzle. The results were verified through experiments on the two types of nozzles. [ABSTRACT FROM AUTHOR]

The elastic strain energy release rate and seismic waves emitted during earthquakes are controlled by the on-fault temporal evolution of the shear stress during rupture propagation. High velocity friction experiments highlighted that shear stress on the fault surface evolves rapidly during seismic slip pulses. This temporal evolution of shear stress is controlled by both fault weakening at seismic slip initiation and re-strengthening rate towards the end of slip. While numerous studies focused on fault weakening, less attention was given to co-seismic re-strengthening processes. Here we performed 53 friction experiments (normal stress ≤30 MPa, slip-rate ≤6.5 m s−1) imposing constant slip acceleration and deceleration (7.8 m s−2), on cohesive Carrara marble (99% calcite) and micro-gabbro (silicate-built rock) under dry, vacuum and water pressurized conditions. Microstructural observations showed that micro-gabbro accommodated seismic slip by bulk melting of the sliding surfaces, whereas Carrara marble by coupled decarbonation and grain-size dependent crystal plastic processes. Under room humidity conditions and low imposed power density (i.e., product of normal stress per slip rate), re-strengthening rate during the deceleration stage was up to ∼ 17 times faster in marble than in micrograbbro. In the latter, the re-strengthening rate increased slightly with the power density. The presence of water enhanced further this trend. On the contrary, in marbles the re-strengthening rate decreased drastically with power density and in the presence of water. Our experimental observations highlighted the first order importance of the mineralogy and rheology of the slip zone materials and, to a second order, of the presence of water in controlling co-seismic re-strengthening of faults during seismic slip deceleration. • Effect of rock composition and water content on fault re-strengthening during earthquakes. • Re-strengthening rate is faster in carbonate-than silicate-bearing rocks at low power density. • In silicate rocks, re-strengthening rate increases with power density and in presence of water. • In carbonate rocks, re-strengthening rate decreases with power density and in presence of water. • Silicate rocks promote intense high frequency radiation during deceleration of the seismic slip. [ABSTRACT FROM AUTHOR]

[Display omitted] • Removal of the reaction product from Ru surface is required for efficient hydrogenation. • Solvent of choice should display high polarity combined with protic character. • Addition of H 2 O to polar solvents enhances solvating ability. • In biphasic solvents orientation of Ru towards H 2 O enables active phase cleansing. • Substituent electron affinity and ring position affect the catalytic performance. The paper reports on the solvent and the substituent effects in hydrogenation of aromatic ketones (acetophenone and its derivatives) in the presence of Ru catalyst supported on functionalized gel-type methacrylate-styrene resin under very mild conditions (1 bar H 2 , 40 °C). The investigated solvents included methanol, 2-propanol, tetrahydrofuran, toluene, isooctane, and cyclohexane, with and without addition of water. The best catalytic activity was obtained in biphasic solvent system consisting of isooctane/water (1:1). In methanol and 2-propanol the beneficial role of water was observed. The effects are discussed in terms of solvent protic/aprotic and polar/apolar properties. The impact of substituents depended on their electron-donating/withdrawing character, and on the position on the aromatic ring of acetophenone. The presence of electron donating substituents tended to increase the reaction rate, and the electron withdrawing group slowed down the process. Steric effect was observed for methylacetophenone isomers with CH 3 group at ortho, meta and para positions. [ABSTRACT FROM AUTHOR]

Abstract Seismic responses of immersed tube tunnel segments were obtained via a series of shaking table tests. The experiment took water effect into consideration in comparison with the existing researches published so far. Details focusing on test equipment, materials, similitude, experimental approach and cases are presented. Response data under 4 kinds of seismic waves whose peak accelerations were modified to 0.1 g, 0.2 g, 0.4 g at 4 water levels were acquired and analyzed. Results show that characteristics of seismic waves, wave amplitude and water all have effect on seismic response of immersed tube tunnel segments. Water has much greater influence on transverse responses than longitudinal ones. Highlights • Seismic responses of immersed tunnel were obtained via shaking table tests taking water effect into consideration. • Details focusing on test equipment, materials, similitude, experimental approach and cases are presented. • Results show that seismic waves, and water level have effect on seismic response of immersed tunnel. [ABSTRACT FROM AUTHOR]

Water presence and concentration strongly influence CO conversion and C 5+ selectivity in the Fischer Tropsch reaction. In this work, the influence of the water concentration was investigated using a model Ru/Al 2 O 3 (5 wt.%) catalyst. The surface species formed after CO and H 2 adsorption in dry and wet (different water concentrations) conditions were analyzed by FTIR. Firstly, water adsorption was carried out up to complete filling of the pores and then CO was put in contact with the catalyst. The absence of adsorbed CO species in these conditions evidences that CO diffusion in water controls the access of the gas to the active sites and explains the negative effect of high water concentrations reported by some authors. Moreover, the adsorption of a mixture of CO+H 2 +H 2 O, being the water concentration close to that needed to have a monolayer, and a dry mixture of CO+H 2 were carried out and compared. Results evidence that water in this low concentration, is able to gasify the surface carbon species formed by CO dissociation on the metallic sites. This cleaning effect is related to the positive effect of water on CO conversion detected by some authors. [ABSTRACT FROM AUTHOR]

Highly dispersed ∼5 nm PtO x NPs confined on ultralight BN nanoribbon aerogels (PtO x /BN-na) with a 3D interconnected porous network were synthesized and used as catalysts for plasma-assisted partial oxidation of methane. The surface reactive hydroxyl groups or/and •OH radical from the plasma-activated reaction of H 2 O and O 2 on PtO x NPs are suggested as the key to enhance the selective conversion of methane, those can promote CH 4 activation, selective oxidation of chemisorbed CH x and desorption of oxygenate species. [Display omitted] • Ultralight PtO x /BN catalyze the plasma-assisted partial oxidation of methane. • H 2 O vapor promotes the selective oxidation of chemisorbed hydrocarbon species. • H 2 O vapor cofeed facilitates the desorption of oxygenates from the catalysts. Ultralight BN nanoribbon aerogels confined highly dispersed PtO x nanoparticles (NPs) catalysts (PtO x /BN-na) were prepared and utilized for plasma-assisted partial oxidation of CH 4 (POM) in a CH 4 −O 2 flow system with H 2 O vapor cofeed at low temperature. The synergistic effect of H 2 O vapor and Pt 2 /BN-na catalyst overcomes a tradeoff problem between CH 4 conversion and oxygenate selectivity, achieving 95% selectivity towards incomplete oxidation products at a 13% CH 4 conversion. The total oxygenate productivity reached 106.5 mmol oxy g cat −1 h−1, which is one of the best results among the state-of-the-art catalysts for gas and liquid POM reaction. Based on experimental results of D and O18 isotope labelling, in situ OES, and in situ DRIFTS, the surface reactive hydroxyl groups or/and •OH radical, generated from the plasma-activated reaction of H 2 O + O 2 on PtO x NPs active sites, are suggested as key factors to promote the POM reaction. The results of the Catalyst Surface Plasma-Assisted Oxidation Reaction (CSPOR) demonstrate that H 2 O not only promotes the selective oxidation of chemisorbed hydrocarbon species to oxygenate species, but also facilitates the desorption of oxygenates from the catalysts. [ABSTRACT FROM AUTHOR]

HKUST-1 MOF is considered among the most promising materials for methane adsorption. However, the huge decrease in adsorption capacity under humid conditions, due to water hydrolysis of the structure and blockage of open metal sites, decreases its potential. To address this issue, composites of HKUST-1 and γ-Al 2 O 3 particles were synthesized and tested for methane adsorption. MOF impregnation on large particles reduces the pressure drop through the fixed-bed, whereas the known hydrophilicity of the alumina is expected to minimize the water damage to the MOF. Impregnation was performed using two different methods (drip impregnation and solvothermal) with different HKUST-1/Al 2 O 3 initial mass ratios (0.05–1.29 g/g) in a PTFE autoclave. The loading, dispersion and main morphological features were confirmed by PXRD, XPS, SEM, BET, DRIFT and TGA. Water influence was determined by ageing samples in a fixed bed under air with 100% RH for 24 h and 3 consecutive cycles, and methane adsorption capacity was checked before and after the humid treatment. Adsorption capacity of HKUST-1 decreases by about 37%, while composites with low MOF loads (<9%) withstand and even improve the methane adsorption capacity by more than 38%. This effect is more noticeable for a more heterogeneous MOF distribution on the alumina surface, following a similar principle to the methane hydrate formation through a surface promoter, but at milder conditions. Surprisingly, these composites also show a significant improvement in thermal stability. [Display omitted] • HKUST-1/Al 2 O 3 composites decrease pressure drop and improve water stability. • Composites are synthesized by solvothermal and drip impregnation methods. • < 9% HKUST-1 boosts methane adsorption by 38% in aged samples. • Drip impregnation composites show rough surface, cluster formation. • Alumina protects HKUST-1, enhances stability in presence of humidity. [ABSTRACT FROM AUTHOR]