OH Content Research Articles

Thermally stable high numerical aperture integrated waveguides and couplers for the 3 μm wavelength range

The femtosecond laser direct write technique was used to fabricate mid-infrared compatible waveguide couplers into Suprasil 3001, a fused silica glass with an OH content of as low as ≤1 ppm. Smooth positive step-index change multi-scan waveguides were produced with a high index contrast of 1 × 10−2, measured directly using quadriwave lateral shearing interferometry. Waveguides were annealed at 400 °C for 15 h and found to be highly stable, with only <5% reduction in positive index change. Brillouin microscopy and cathodoluminescence are introduced as novel tools that complement Raman mapping and electron microscopy for the investigation of the laser-induced structural changes within the glass matrix, and it was found that although a uniform step index profile is observed across the entire guiding region, different physical mechanisms underpin the index change in the upper and lower sections of the waveguide cross-section, respectively. Waveguides were optimized for mode-matching with optical fibers for the 3.2 μm wavelength range, and evanescent four-port directional couplers with coupling ratios ranging from 5:95 to 50:50 were designed and fabricated. This demonstration opens the door to the development of fully integrated and temperature-stable hybrid chip/fiber systems for the important mid-infrared spectral range.

Construction of core-shell BN-OH@Fe3O4@PAn nanocomposite with ultra-wide microwave absorption and efficiency thermal management

As electronic device integration and power density increase, materials must have brilliant microwave absorption properties and thermal conductivity to solve electromagnetic wave pollution and thermal management problems. In this work, we attempt to construct core-shell hydroxylated boron nitride nanosheets (BN-OH) @Fe3O4@PAn (BFeA) nanocomposites by chemical synthesis and in-situ growth design. The excellent magnetic properties of Fe3O4 and the good electrical conductivity of PAn can form magnetic loss and electrical loss centers to play a synergistic effect in improving microwave absorption capacity. Meanwhile, with the wave-transmitting material BN-OH as the core, the electromagnetic waves can be reflected multiple times within the absorber, which further enhances the microwave absorption capability of BFeA. As a result, the minimum reflection loss (RLmin) of the composites can reach − 49.85 dB at 11.36 GHz, and the effective microwave absorption bandwidth (RL<−10 dB, EAB) is close to 8 GHz (8.5–16.5 GHz) at a thickness of 3 mm. Simultaneously, to improve the thermal conductivity (TC) of the BFeA and reduce the interfacial thermal resistance, we use hydroxyl and dopamine as the interface linking agent at the interfaces of BN-OH and Fe3O4, and Fe3O4 and PAn, respectively. In this case, the TC of BFeA-2 reaches 0.98 W (m K)−1 at a total BN–OH content of only 13 wt. %, nearly 4 times that of the raw material (Fe3O4). This work can provide a reference for developing materials with dual functions of thermal management and microwave absorption.

Physiological and transcriptomic analysis of antioxidant mechanisms in sweet sorghum seedling leaves in response to single and combined drought and salinity stress

ABSTRACT The effects of drought, salinity, and combined stress on ROS and ROS metabolic physiology and transcriptomics in sweet sorghum seedling leaves were evaluated. The results showed that drought stress had little effect on photosynthesis, while the SOD activity, CAT activity, and the expression of their related genes were elevated in leaves, but no excessive accumulation of O2 -, H2O2, or -OH was observed. Under salinity stress, photosynthesis was inhibited, the O2 -, H2O2 and -OH contents increased significantly, and the SOD, POD, CAT activities and the expression of their related genes in leaves were elevated. Under combined stress, photosynthesis was significantly inhibited, the highest accumulation of O2 -, H2O2 and -OH contents occurred, and the SOD and POD activities and the expression of related genes in leaves were significantly increased, but the CAT was significantly decreased. These results collectively indicate that oxidative damage to sweet sorghum seedling leaves was higher with combined stress than with either drought or salinity stress alone. Under combined stress the SOD and POD activities were increased, but the CAT activity in the AsA-GSH cycle was severely reduced, demonstrating that antioxidant mechanisms in seedlings did not play a normal protective role, leaving the plants severely damaged by oxidative stress. Abbreviations: AsA: Ascorbic acid; APX: Ascorbate peroxidase; CAT: Catalase; Chl a: Chlorophyll a; Chl b: Chlorophyll b; Ci: Intercellular CO2 concentration; DHAR: Dehydroascorbate reductase; DEGs: Differentially expressed genes; DW: Dry weight; ETR: Photosynthetic electron transport rate; FW: Fresh weight; Fv/Fm: Original light energy conversion efficiency; GPX: Glutathione peroxidase; GR: Glutathione reductase; Gs: Stomatal conductance; GSH: Oxidized glutathione; H2O2: Hydrogen peroxide; MDA: Malondialdehyde; MDHAR: Monodehydroascorbate reductase; O2-: Superoxide anion; PCA: Principal component analysis; PCD: Programed cell death; PEG-6000: Polyethylene glycol 6000; POD: Peroxidase; Pn: Photosynthetic rate; Pro: Proline; qRT–PCR: Quantitative real-time PCR; RNA-seq: RNA Sequencing; ROS: Reactive oxygen species; RWC: Relative water content; RMP: Relative membrane permeability; SOD: Superoxide dismutase; SW: Saturation weight; Tr: Transpiration rate; ΦPSII: Actual photochemical efficiency; -OH: Hydroxyl radical

Effect mechanism of nitrogen injection into fire-sealed-zone on residual-coal re-ignition under stress in goaf

Coal is the one of foundations of energy and economic structure in China, while the unsealing of coal mine fires would cause a great risk of coal re-ignition. In order to explore the influence of pressure-bearing state on the re-ignition characteristics for residual coal, the uniaxial compression equipped with a temperature-programmed device was built. The scanning electron microscope, synchronous thermal analyzer and Fourier transform infrared absorption spectrometer was applied to investigate the microscopic structure and thermal effect of the coal samples. Moreover, the microscopic effect of uniaxial stress on coal re-ignition is revealed, and the re-ignition mechanism is also obtained. As the uniaxial stress increasing, the number, depth and length of the fractures of the pre-treated coal increases. The application of uniaxial stress causes the thermal conductivity to change periodically, enhances the inhibition of injecting nitrogen on heat transfer and prolonges the duration of oxidation exothermic. The content of oxygen-containing functional groups has a high correlation with apparent activation energy, and coal samples at 6 MPa is more probability to re-ignite while the fire zone is unsealed. Uniaxial stress could control the re-ignition mechanism by changing the structure of fractures and pores. The side chains and functional groups of coal structure are easier to be broken by thermal-stress coupling. The higher the ·OH content, the more difficult coal samples would be re-ignited. The research results would lay a solid theoretical foundation for the safe unsealing of closed fire-areas underground, tighten the common bond between the actual industry and the experimental theory in closed fire-areas underground, and provide the theoretical guidance for coal re-ignition preventing.

In-situ generation of H2O2 by zero valent iron to control depolymerization of lignocellulose in composting niche.

Lignocellulosic degradation is a bottleneck of bioconversion during the composting process. In-situ generation of H2O2 in the composting system was an ideal method for efficiently promoting lignocellulase degradation, and zero valent iron (ZVI) was concerned because it can generate H2O2 by reducing dissolved oxygen. This study focused on the effects of ZVI treatment on lignocellulose degradation, microbial communities, and carbohydrate-active enzymes (CAZymes) genes during composting. Its results indicated that ZVI increased H2O2 content during composting, accompanied by the formation of •OH. The degradation rates of lignin, cellulose and hemicellulose in ZVI group (20.77%, 30.35% and 44.7%) were significantly higher than in CK group (17.01%, 26.12% and 38.5%). Metagenomic analysis showed that ZVI induced microbial growth that favored lignocellulose degradation, which increased the abundance of Actinobacteria and Firmicutes but reduced Proteobacteria. At the genus level, the abundance of Thermomonospora, Streptomyces, and Bacillus significantly increased. In addition, glycoside hydrolases and auxiliary activities were important CAZymes families of lignocellulose degradation, and their abundance was higher in the ZVI group. Redundancy analysis showed that the increased H2O2 and •OH content was a critical factor in improving lignocellulose degradation. Overall, H2O2 as a co-substrate enhanced the enzymatic efficiency, •OH unspecifically attacked lignocellulose, and the increase in functional microbial abundance was the main reason for promoting lignocellulose degradation in composting.

Experimental study on chemical structure and wetting influence of imidazole ionic liquids on coal

Three imidazole ionic liquid solutions were selected to handle coal with distinct degrees of metamorphism to research the influences of cation and anion ions in ionic liquids on functional groups and the relationship between functional groups and coal wettability. The chemical framework of coal was researched by FTIR and the wetting peculiarity of the coal was researched by contact angle meter. FTIR analysis showed that the cation and anion ions in ionic liquids significantly altered the framework of the coal. The contact angle measurement results demonstrated that compared with coal using pure water, the coal handled with ionic liquids showed a smaller contact angle. Finally, the relationship between contact angle and functional group content was analyzed. The results showed that the anions and cations of different ionic liquids can increase the content of hydrophilic groups in coal dust with different metamorphisms, such as OH···O, CO, and CO, and destroy the hydrophobic groups in the dissolved coal structure, such as CH2, CH and the benzene ring 3 substitutions. And 2 % [Emim][BF4] can effectively reduce the coal contact angle and improve the wettability of coal dust. The content of CO and OH···O groups had the greatest correlation with the contact angle, which were 0.845 and 0.754, respectively. By studying the influence of anions and cations in ionic liquids on the content of functional groups in coal, the effect of specific anions and cations on coal structure was further discovered, which provides a theoretical basis for the development of new ionic liquids with specific functions, and provides guiding significance for ionic liquid solutions to improve the wettability of coal and reduce the dust concentration.

Past eruptions of a newly discovered active, shallow, silicic submarine volcano near Tokyo Bay, Japan

Abstract Oomurodashi is a newly discovered active, shallow, silicic submarine volcano only 60 km from Tokyo Bay. We reveal its past eruptive activity, and potential future hazards, by examining volatile contents of its subaerial and submarine pumice and lava deposits. These novel data for shallow silicic submarine eruption products were obtained using new Fourier transform infrared spectroscopy (FTIR) analytical techniques for vesicular and hydrated glasses. All matrix glasses have H2O species data consistent with low-temperature hydration following eruption. We therefore used unaltered OH data to investigate past eruptions. Geochemistry confirmed that Oomurodashi was the source of a ca. 13.5 ka subaerial tephra deposit on nearby inhabited islands. We infer from pumice OH contents and tephra characteristics that this deposit was formed by explosive submarine phreatomagmatic activity that produced the shallow crater in the submarine edifice. OH contents of in-place submarine lavas are lower than expected for their current water depth; comparison with past sea level implies that these lavas erupted at ca. 7–10 ka and ca. 14 ka when sea level was lower. Oomurodashi has also erupted submarine pumice with different densities, quench depths, and dispersal histories; however, any pumice sufficiently buoyant to produce floating pumice rafts will have been lost from the local geological record, so pumice rafts remain a potential future hazard.

One-step lignocellulose fractionation using acid/pentanol pretreatment for enhanced fermentable sugar and reactive lignin production with efficient pentanol retrievability

To valorize whole lignocellulosic biomass, this study proposed a biphasic solvent system using dilute acid (DA)/pentanol pretreatment. Effects of the key factors, i.e., temperature and pentanol concentration, on aspen were evaluated. Under identified optimal pretreatment conditions (160 °C, 60% pentanol), 85% and 91% of lignin and hemicellulose were solubilized in separate organic and liquid phases, respectively, while 91.1% of cellulose was retained in solid fraction. Enzymatic digestibility efficiency of pretreated cellulose was ∼ 6.4-times higher than that of untreated biomass. Notably, excellent pentanol recovery rates were obtained after four-times recycling (84%) with great cellulose digestibility (81%) and delignification (71%) performance. The recovered lignin contained low levels of contaminated sugars (<1%), while it could stabilize and protect high amounts of β-O-4 bonds. Besides, high phenolic OH content was found in lignin, which could be utilized for lignin-based biomaterials. Therefore, DA/pentanol pretreatment is an innovative promising technology for lignocellulosic valorization towards biorefinery.

Tuning Single-Polymer Growth via Hydrogen Bonding in Conformational Entanglements.

Synthetic polymers have widespread applications in daily life and advanced materials applications. Making polymers efficiently and controllably is highly desired, for which modulating intramolecular and intermolecular interactions have been an effective approach. Recent real-time single-polymer growth studies uncovered nonequilibrium conformational entanglements that form stochastically under living polymerization conditions and which appear to plausibly play key roles in controlling the polymerization kinetics and dispersion. Here, using magnetic tweezers measurements, we study the real-time polymerization dynamics of single polynorbornene-based polymers in which we systematically tune the hydrogen-bonding interactions by titrating the OH content in the monomers and the formed polymers during ring opening metathesis polymerization. Using norbornenes with and without a hydroxyl group and a nonreactive monomer analogue, we show that intrachain and intermolecular hydrogen bonding compete, and both alter the microscopic properties of the nonequilibrium entanglements, leading to surprising multiphasic dependences of polymerization dynamics on the polymer’s OH content. We further formulate a simple model to rationalize quantitatively the observed multiphasic behaviors by considering the different scaling relations of intrachain and intermolecular hydrogen bonding on the OH content. These results provide insights into the interconnected roles of intra-/intermolecular interactions, polymer chain conformations, and free monomers in solution in affecting polymerization kinetics and dispersion, and point to new opportunities in manipulating polymerization reactions.

Cellulose Hollow Annular Nanoparticles Prepared from High-Intensity Ultrasonic Treatment.

Cellulose nanomaterials, such as cellulose nanocrystals (CNCs), have received enormous attention in various material research fields due to their unique properties and green/sustainable nature, among other qualities. Herein, we report hollow-type annular cellulose nanocrystals (HTA-CNCs), which are generated by following a high-intensity ultrasonic treatment. The advanced aberration-corrected transmission electron microscopy results reveal that HTA-CNCs exhibit ring structures with a typical diameter of 10.0-30.0 nm, a width of 3.0-4.0 nm, and a thickness of 2.0-5.0 nm, similar to those of elementary crystallites. The X-ray diffraction measurements show that the as-prepared HTA-CNCs maintain the cellulose I structure. The changes in structure and hydrogen-bonding characteristics of HTA-CNCs are further determined based on the FT-IR results after deconvolution fitting, showing that three types of hydrogen bonds decrease and the content of free OH increases in HTA-CNCs compared with those in the original CNCs. Furthermore, molecular dynamics simulation is carried out to support the experimental study. The formation of HTA-CNCs might be attributed to the structural change and entropy increase. The hollow-type annular CNCs may have broad value-added applications as cellulose nanomaterials in different fields.

Effect of different functional groups on CH4 adsorption heat and surface free energy of vitrinite during coalification

Here vitrinite of various coal ranks was collected to study the characteristics of initial isosteric heat of adsorption (Qst0) and surface free energy (Δσ) by the isothermal methane-adsorbing at various temperatures on dry basis. The surface area of demineralized dry samples was examined for the calculation of Qst0 and Δσ, and the macromolecular structures of dry vitrinite samples were determined using Fourier transform infrared spectroscopy and 13C nuclear magnetic resonance experiments. The Qst0 shows no obvious correlations with oxygen-containing groups, however, there is a positive correlation between the alcoholic hydroxyl group (R–OH) and maximal surface free energy (Δσmax), indicating that the decreasing in R–OH content with the increasing coal rank can reduce adsorption capacity. Qst0 decrease as the amount of nonprotonated aromatic carbon attached to phenolic (including phenoxy or phenol groups) increases, indicating that phenoxy or phenol group loss with maturation is beneficial to increasing Qst0. As the degree of coal metamorphism increases, the aliphatic side chains gradually decline, inducing Qst0 initially decreases and then increases. For aromatic groups, with increases of aromatic carbons, aromatic bridgehead carbons, and ratio of aromatic CC to aromatic CH, Qst0 initially decreases and then increases.

Effect of Yb3+ on the Structural and Visible to Near-Infrared Wavelength Photoluminescence Properties in Sm3+-Yb3+-Codoped Barium Fluorotellurite Glasses.

We report on the Sm3+ and Sm3+:Yb3+-doped barium fluorotellurite glasses prepared using the conventional melting and quenching method. The spectroscopic characterisations were investigated with Raman and FTIR to evaluate the glasses’ structural and hydroxyl (-OH) content. The Raman analysis revealed a structural modification in the glass network upon adding and increasing the Yb3+ concentration from a TeO3 trigonal pyramid to a TeO4 trigonal bi-pyramid polyhedral. At the same time, the FTIR measurements showed the existence of -OH groups in the glass. Thus, under the current experimental conditions and nominal composition, the -OH group contents are too large to enable an effective removal. The near-infrared region of the absorption spectra is employed to determine the nephelauxetic ratio and bonding parameters. The average nephelauxetic ratio decreases, and the bonding parameter increases with the increasing Yb3+ content in the glasses. A room temperature visible and near-infrared photoluminescence ranging from 500 to 1500 nm in wavelength and decay properties were investigated for glasses doped with Sm3+ and Sm3+-Yb3+ by exciting them with 450 and 980 nm laser sources. Exciting the Sm3+- and Sm3+-Yb3+-doped glasses by 450 nm excitation reveals a new series of photoluminescence emissions at 1200, 1293, and 1418 nm, corresponding to the 6F11/2 state to the 6HJ (J = 7/2, 9/2, 11/2) transitions. Under the 976 nm laser excitation, a broad photoluminescence emission from 980 to 1200 nm was detected. A decay lifetime decreased from ~244 to ~43 μs by increasing the Yb3+ content, ascribing to concentration quenching and the OH content.

Characterization of different types of lignin and their potential use in green adhesives

Lignin is the second most abundant component of lignocellulosic biomass after cellulose. This aromatic polymer has an immense potential for applications in composite materials, organic synthesis and pharmaceutical industries. In this study, different types of lignin (Kraft and three organosolv lignins from different processes) were characterized and incorporated into a pressure sensitive adhesive (PSA) aqueous formulation based on polycarboxylate polyether (PCE), which was selected for its low ecotoxicity. All lignin samples were evaluated and compared using various characterization methods, such as GPC, 13C NMR and 31P NMR spectroscopy. Thermal properties were investigated using TGA and DSC techniques. Based on these analyses, organosolv lignin samples presented lower molecular weight (Mw), lower polydispersity and higher amounts of phenolic OH groups. Optimizing molecular weight and hydroxyl contents were found to be the main factors affecting PSA properties. One of our formulations (5-OL-B2), which incorporated the organosolv lignin of lowest molecular weight (Mw ≈ 1270 g/mol) and highest OH content (~7.08 mmolOH/glignin), leads to an adhesive performance similar to that the commercial PSA, such as low peel-off losses and lower distance traveled by the ball (higher tackiness).

Estimation of Li and OH contents in (Li,Al)-bearing tourmalines from Raman spectra

Estimation of Li and OH contents in (Li,Al)-bearing tourmalines from Raman spectra

Simulating the diffusion of hydrogen in amorphous silicates: A ‘jumping’ migration process and its implications for solar wind implanted lunar volatiles

We use molecular dynamics (MD) simulations to better explain the movement of atomic hydrogen in amorphous silica and quantify the planetary science implications of these findings. Previous MD simulations had a large range of predicted values and did not agree well with experiment. Our simulations sample atomic motion for a longer duration and consider a wider range of temperatures than previous simulations. In contrast to constant atomic motion, the hydrogen atoms were shown to undergo random intermittent jumps from one oxygen atom to another, the number of which increase with temperature. Predicted diffusion coefficients had a better agreement to experimental values than previous MD simulations, suggesting the importance of longer simulation durations for better statistics. The low activation energy and jumps observed at lunar temperatures do not support the theory of diurnal variations in OH content for an undamaged amorphous silica surface. Instead, we conclude that energetic solar wind impacts can induce two competing atomic hydrogen motion processes in the exposed surface: A prompt effect that induces jumps in the temperature spike volume, but also a long-term effect of damage in the structure that traps atomic hydrogen. We then use SDTrimSP to quantify the damage created during exposure and MD to demonstrate the H retention and trapping near these defects. Damage was shown to be dependent on impact energy, with defects easily retaining implanted hydrogen. MD results like those presented herein on unweathered surfaces are therefore most relevant to magnetic anomalies. As a result, we demonstrate the importance of lunar volatile models to account for the damage state of the substrate when modelling hydrogen diffusion, retention, and subsequent OH/water production.

A combination of deep eutectic solvent and ethanol pretreatment for synergistic delignification and enhanced enzymatic hydrolysis for biorefinary process

A novel pretreatment system containing deep eutectic solvents and ethanol (DES-E) for synergistic carbohydrate conversion and delignification was reported in this study. The DES-E pretreatment resulted in an enhanced glucose yield compared to individual DES and ethanol pretreatment for the three tested biomass, including Broussonetia papyrifera, corn stover and pine. To further explore the delignification mechanism, the solubilized lignin and residual lignin from Broussonetia papyrifera was recovered and extracted, then thoroughly characterized. The highest total OH content was found in the DES-E solubilized lignin, which could be used as antioxidant. The presence of ethanol in pretreatment liquor could protect the β-O-4 substructure from breakage and reduce lignin condensation, which favors the subsequent enzymatic hydrolysis. Comparable glucose yield and delignification performance was achieved by recycled DES. DES-E pretreatment offers a promising method for lignin isolation and cellulose digestibility improvement simultaneously.

Experimental Study on Carbonation Durability of Kaolin Strengthened with Slag Portland Cement.

Slag Portland cement is an environmentally friendly and energy-saving product, which is widely used in cement-reinforced soil. This study used slag Portland cement-reinforced soil as the research object and P.O 42.5 + kaolin (POK) as the reference group. The carbonation depth and strength of P.S.A 42.5 + kaolin (PSK) at different curing times were analyzed using carbonation depth, uniaxial ground pressure strength, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The test results show the following: (1) The active substances in PSK samples can react with calcium hydroxide produced during cement hydration and can reduce the content of OH−. The PSK samples react with OH− and CO2 in the carbonation environment. Both processes considerably reduce the content of OH−. (2) Due to the decrease in OH− content, the carbonation durability of slag Portland cement-reinforced soil is significantly less than that of ordinary Portland cement. (3) The carbonation of slag Portland cement-reinforced soil improves its strength. (4) The results of SEM + EDS and XRD confirm the carbonation depth and strength of the POK and PSK samples. The results show that PSK has important applications in subgrade or building grouting materials and in cement-soil mixing piles (walls).

Characterization of oxyfluoride glasses doped with rare-earth ions through structural, thermal, and optical application thereof

Novel transparent glasses and glass-ceramics were fabricated by using melt-quenching technique with the following composition: TeO2–WO3–Nb2O5–KF–La2O3 doped with Tm2O3. Different properties and physical parameters of these glasses were investigated. As the concentration of Tm3+ ions increases, the linear refractive index increases while the optical energy gap decreases. With high Tm3+ ion concentration creates nucleation in the glass matrix this was investigated by x-ray diffraction. The Judd-Ofelt parameters used to calculate the electric and magnetic dipole transition probabilities, branching ratios, and radiative lifetimes of various excited states of Tm3+-doped parent glass. The emission cross section values for the 3F4→3H6 transition computed by using the McCumber hypothesis. The stimulated emission cross section σeFL(λ) and gain values of fabricated glass increase with Tm3+ ions. The spectroscopic quality and figure of merit (FOM) gain (σeFL(λ)×τR) factors were evaluated for the prepared transparent glass. Furthermore, the produced glasses were demonstrated to have low OH content and they have high fluoride ion content. These important properties of the glasses and glass-ceramics make them suitable for use in photonic applications.

Long-term performance of granular activated carbon electrode system for the removal of amoxicillin

Three-dimensional electrode reactor, packed with conductive particles, is more cost-effective than traditional two-dimensional electrode reactor. In this study, granular activated carbon (GAC) was applied as particle electrode, then the long-term performance on amoxicillin (AMX) removal and activated carbon regeneration of the GAC particle electrode oxidation process (GAC EOP) was investigated, and the GAC adsorption process (GAC ADS) was carried out for comparison. Both of them ran continuously to remove AMX. Because of the regeneration effect of electrochemical action, the GAC EOP showed a more stable physisorption capacity than GAC ADS, with less change in micropore volume, pore size distribution and surface morphology of GAC. The result of XPS revealed the AMX chemisorption mechanism: the carbonyl (CO) and phenolic hydroxyl (OH) on activated carbon combined with carboxyl (COOH) and ammonium group (NH3+) on AMX, respectively. Correspondingly, the content of CO and OH on GAC fell significantly during the GAC ADS. However, due to the chemical bond regeneration effect of electrolysis, noticeable declines were not observed in GAC EOP, which ensured the stable chemisorption capacity of this system. It was shown that during the 50 consecutive runs, the AMX removal in GAC EOP was always higher than 60%. Even the removal efficiency showed an upward tendency, with the average value reached 86.1% and 99.1% in the 31–40 and 41–50 run times respectively. It was because of the rising specific surface area of GAC and the effect of electro-polarization, which made it more meaningful to explore the long-term performance of three-dimensional electrode reactor.

The influence of OH content on elastic constants of topaz [Al2SiO4(F,OH)2

Abstract Topaz, Al2SiO4(OH)xF(2–x), may play a significant role in transporting water and fluorine into the Earth’s interior at subduction zones. Seismological detection of topaz gives us insights into the transport mechanisms of water and fluorine but requires a thorough understanding of its elastic properties. The influence of OH content on elastic constants of topaz has not been fully understood, though experimental and theoretical studies have been done on topaz with various OH contents. We thus determined elastic constants of topaz for five natural single-crystal specimens with different OH contents (x = 0.28~0.72) via the sphere resonance method at an ambient condition. Our determined C11, C22, C44, C66, C12, C23, and C31 increase with OH content while C33 and C55 decrease. For the change in OH molar content from 0.0 to 1.0, relatively large changes (&amp;gt;3.0%) are seen in C33 [8.0(6)%], C55 [4.9(6)%], and C22 [3.1(7)%]. The OH content dependence of elastic constants is qualitatively similar to that of theoretically determined values except for C11. The theoretical value of C11 decreases as the OH molar content increases from 0.0 to 1.0, whereas the experimental value of C11 slightly increases. Our elastic constants are significantly higher (&amp;gt;3%) than theoretically determined values, especially in diagonal components (Cii). The theoretical lower values must be related to the used lattice parameters, which are systematically larger than the measured lattice parameters. The theoretical approach should be modified to reproduce measured lattice parameters and lead to the agreement of theoretical and experimental elastic constants. Our results provide a clue to a better understanding of the elasticity of topaz and a basis for the seismological detection of subducted oceanic sediments.