Hydration Dehydration Research Articles

Structural Formation of Soil Concretes Based on Loam and Fly Ash, Modified with a Stabilizing Polymer Additive.

Finding new ways of recycling production waste to improve the characteristics of various building materials is an urgent scientific task. This article substantiates the possibility of the disposal of fly ash in the composition of soil concrete, which is used in the construction of the structural layers of road pavements, foundations of buildings and structures, as well as sites for various purposes. The scientific novelty lies in the fact that the structure formation of soil concretes based on loam and fly ash and modified with a stabilizing additive is being studied for the first time. It was found that the investigated fly ash, according to its hydraulic properties, is classified as latent active and can be introduced into the compositions of road soil concrete modified with additives of various resources. The effectiveness of the complex method of stabilization, due to changes in soil properties as a result of the use of the binding and stabilizing additives of polymer nature “Kriogelit”, is shown. It was found that the optimal content of binder and fly ash in the samples was 8 and 10 wt.%, respectively. It was established that the use of the stabilizing additive “Kriogelit” makes it possible to obtain soil concrete with the highest strength (compressive strength 2.5 MPa, flexural strength 0.5 MPa) and frost resistance of at least F15. The microstructure, the degree of dehydration and carbonization, and the phase composition of the initial raw mixtures and soil concretes stabilized with the addition of “Kriogelit” were studied by methods of scanning electron microscopy, X-ray diffraction analysis, differential scanning calorimetry, thermogravimetry, and infrared spectroscopy. It was shown that organo-mineral complexes, with the participation of polymer and montmorillonite, are formed in stabilized soil concrete. It was revealed that structure formation is accompanied by the physical adsorption of the polymer on active centers of silicate minerals, carbonization, and hydration–dehydration processes. It was found that the reason for the increase in the strength of stabilized soil concretes is the hydrophobization of the porous structure of minerals, as well as the formation of calcium oxide silicate and dicalcium hydrated silicate. By the method of performing biotests with the test objects Daphnia magna Straus and Chlorella vulgaris Beijer, it was proven that the developed road concretes modified with the stabilizing additive “Kriogelit” do not have an acute toxic effect on the test objects and are safe for the environment and human health.

Synergistic Stimulation of Metal-Organic Frameworks for Stable Super-cooled Liquid and Quenched Glass.

Metal-organic framework (MOF) glasses are a fascinating new class of materials, yet their prosperity has been impeded by the scarcity of known examples and limited vitrification methods. In the work described in this report, we applied synergistic stimuli of vapor hydration and thermal dehydration to introduce structural disorders in interpenetrated dia-net MOF, which facilitate the formation of stable super-cooled liquid and quenched glass. The material after stimulus has a glass transition temperature (Tg) of 560 K, far below the decomposition temperature of 695 K. When heated, the perturbed MOF enters a super-cooled liquid phase that is stable for a long period of time (>104 s), across a broad temperature range (26 K), and has a large fragility index of 83. Quenching the super-cooled liquid gives rise to porous MOF glass with maintained framework connectivity, confirmed by EXAFS and PDF analysis. This method provides a fundamentally new route to obtain glassy materials from MOFs that cannot be melted without causing decomposition.

Photoswitchable Fluorescent Proteins: Mechanisms on Ultrafast Timescales.

The advancement of super-resolution imaging (SRI) relies on fluorescent proteins with novel photochromic properties. Using light, the reversibly switchable fluorescent proteins (RSFPs) can be converted between bright and dark states for many photocycles and their emergence has inspired the invention of advanced SRI techniques. The general photoswitching mechanism involves the chromophore cis-trans isomerization and proton transfer for negative and positive RSFPs and hydration–dehydration for decoupled RSFPs. However, a detailed understanding of these processes on ultrafast timescales (femtosecond to millisecond) is lacking, which fundamentally hinders the further development of RSFPs. In this review, we summarize the current progress of utilizing various ultrafast electronic and vibrational spectroscopies, and time-resolved crystallography in investigating the on/off photoswitching pathways of RSFPs. We show that significant insights have been gained for some well-studied proteins, but the real-time “action” details regarding the bidirectional cis-trans isomerization, proton transfer, and intermediate states remain unclear for most systems, and many other relevant proteins have not been studied yet. We expect this review to lay the foundation and inspire more ultrafast studies on existing and future engineered RSFPs. The gained mechanistic insights will accelerate the rational development of RSFPs with enhanced two-way switching rate and efficiency, better photostability, higher brightness, and redder emission colors.

Water-Based Dynamic Depsipeptide Chemistry: Building Block Recycling and Oligomer Distribution Control Using Hydration-Dehydration Cycles.

The high kinetic barrier to amide bond formation has historically placed narrow constraints on its utility in reversible chemistry applications. Slow kinetics has limited the use of amides for the generation of diverse combinatorial libraries and selection of target molecules. Current strategies for peptide-based dynamic chemistries require the use of nonpolar co-solvents or catalysts or the incorporation of functional groups that facilitate dynamic chemistry between peptides. In light of these limitations, we explored the use of depsipeptides: biorelevant copolymers of amino and hydroxy acids that would circumvent the challenges associated with dynamic peptide chemistry. Here, we describe a model system of N-(α-hydroxyacyl)-amino acid building blocks that reversibly polymerize to form depsipeptides when subjected to two-step evaporation–rehydration cycling under moderate conditions. The hydroxyl groups of these units allow for dynamic ester chemistry between short peptide segments through unmodified carboxyl termini. Selective recycling of building blocks is achieved by exploiting the differential hydrolytic lifetimes of depsipeptide amide and ester bonds, which we show are controllable by adjusting the solution pH, temperature, and time as well as the building blocks’ side chains. We demonstrate that the polymerization and breakdown of the depsipeptides are facilitated by cyclic morpholinedione intermediates, and further show how structural properties dictate half-lives and product oligomer distributions using multifunctional building blocks. These results establish a cyclic mode of ester-based reversible depsipeptide formation that temporally separates the polymerization and depolymerization steps for the building blocks and may have implications for prebiotic polymer chemical evolution.

Effect of 3D-printed sand molds on the soundness of pure copper castings in the vicinity of as-cast surfaces

Although the use of three-dimensional (3D)-printed sand molds enables both the formation of near-net shapes and the manufacture of ultra-high-mix and ultra-low-volume pure copper castings, detailed clarification is required regarding the correspondence between the use of such molds and the generation of casting defects. In this study, the effects of 3D-printed molds on the soundness of pure copper castings in the vicinity of as-cast surfaces were investigated. For castings with high and medium oxygen contents, multiple cavities were observed in the vicinity of the as-cast surfaces of the portions of the castings obtained from 3D-printed molds made of artificial mullite sand and furan binder. However, cavities were not generated in castings with low oxygen content (irrespective of the mold materials) or those obtained from CO2 molds made of silica sand and water glass via the CO2 process (irrespective of the oxygen content). The analyses of 3D-printed molds show that gases such as combustion gases of organic compounds and water vapor from the dehydration of hydrates were generated by heating. Moreover, for castings with high oxygen content, the generation of cavities was prevented using 3D-printed molds impregnated with water glass and held at 400 °C. However, our analyses demonstrated the occurrence of chemical reactions between molten copper or Cu2O and SiO2, which caused the burning of silica sand on as-cast surfaces (i.e., penetration into the CO2 molds) in castings with high and medium oxygen contents. These results indicate that the adequate deoxidization of the melt and the rapid formation of a solidified shell after pouring are effective in enabling the utilization of 3D-printed molds and that combining granular sand that is non-reactive to molten copper with an inorganic binder produces ideal molds for pure copper castings.

The Association between Heat Exposure and Hydration Status Among Production Workers in Fish Processing Company

Background: Hot work environment can cause various subjective and objective complaints for workers. When workers perform activities under hot work environment, their body will react by balancing the amount of heat received by the body from outside the body and the loss of water in the body. Hydration status is the condition achieving the balance between water intake and water discharge from the body. Bad hydration status or de-hydration can cause various changes in the body physiological functions. This study was intended to see the association between heat exposure and hydration among production workers in Fish Processing Company Sawangan, Depok.Method : A cross sectional study with 88 respondents, selected as a total sampling. The study was conducted on November 2017 until January 2018. Data analysis were used by SPSS version 20.0.Result: There is no significant difference between the specific gravity of urine before and after working (p=0.076). However, 37.5% of the workers had dehydration. There is a significant association between the work environment temperature and hydration status (p=0.002), and also between water intake and status of hydration (p=0.013). Work environment temperature is the most dominant risk factor to influence dehydration (p=0.000; OR= 9.305; 95%CI=2.727-31.748)Conclusions: There is a significant association between heat exposure and hydration status (p=0.000; OR=9.305). The number of workers that were exposed to heat and experienced dehydration is 33 people (37.5%). Water intake turns to be the individual factor that influences the status of hydration of the workers exposed to heat. The work factor that influences the hydration status of the workers is the work environment temperature.

Distinct Hybrid Hydrates of Paritaprevir: Combined Experimental and Computational Assessment of their Hydration–Dehydration Behavior and Implications for Regulatory Controls

Distinct Hybrid Hydrates of Paritaprevir: Combined Experimental and Computational Assessment of their Hydration–Dehydration Behavior and Implications for Regulatory Controls

Dehydration and Rehydration Mechanisms of Pharmaceutical Crystals: Classification Of Hydrates by Activation Energy

Dehydration strongly influences the stability of hydrate drug substances. Consequently, the ability to predict dehydration of crystalline hydrate using the intermolecular interactions of water molecules contained in the crystals is essential for drug development. The conventional method employed to predict the propensity for dehydration uses the dehydration temperature, which is related to how tightly water molecules are bound in the crystal lattice. However, it is difficult to predict the dehydration propensity of a particular hydrate using only the dehydration temperature because other kinetic factors affect dehydration behavior, such as intermolecular interactions, and drug-substance-to-water molar ratio in a hydrate. In this study, we explored the use of the dehydration activation energy Ea and rehydration behavior to classify 11 pharmaceutical hydrates into three classes according to their kinetic behavior related to the thermodynamic factors of hydrates. There is good agreement between these classes and hydrate crystal structures determined from single-crystal X-ray diffraction, and thus, the classification reflects their crystal structural features. We compared Ea to the dehydration temperatures for each class and found that Ea plays a crucial role and is better than the temperature for quantitative differentiation of the dehydration propensities in these hydrates.

The Relationships between Water Intake and Hydration Biomarkers and the Applications for Assessing Adequate Total Water Intake among Young Adults in Hebei, China.

Water is an essential nutrient for humans. A cross-sectional study was conducted among 159 young adults aged 18–23 years in Hebei, China. The total drinking fluids and water from food were obtained by 7-day 24 h fluid intake questionnaires and the duplicate portion method, respectively. Pearson’s correlation coefficients were performed to determine the relationship between fluid intake and 24 h urinary biomarkers and plasma biomarkers. A multivariable partial least squares (PLS) model was used to identify the key predictors in modeling the total water intake (TWI) with 24 h urine biomarkers. Logistic regressions of the TWI against binary variables were performed, and the receiver operating characteristic curve (ROC) was analyzed to determine the cutoff value of the TWI for the optimal hydration status and dehydration without adjustments to favor either the sensitivity or specificity. In total, 156 participants (80 males and 76 females) completed the study. Strong relationships were found between the total drinking fluids, TWI, and 24 h urine biomarkers among young adults, especially for the 24 h urine volume (r = 0.784, p < 0.001; r = 0.747, p < 0.001) and osmolality (r = −0.589, p < 0.001; r = −0.477, p < 0.001), respectively. As for the FMU and plasma biomarkers, no strong relationships were found. The percentages of the variance in TWI explained by the PLS model with 13 urinary biomarkers were 66.9%. The optimal TWI values for assessing the optimal hydration and dehydration were 2892 mL and 2482 mL for young males, respectively, and 2139 mL and 1507 mL for young females, respectively. Strong relationships were found between the TWI, total drinking fluids, and 24 h urine biomarkers, but not with the FMU and plasma biomarkers, among young adults, including males and females. The 24 h urine biomarkers were more sensitive than the first morning urinary biomarkers in reflecting the fluid intake. The TWI was a reliable index for assessing the hydration statuses for young adults in free-living conditions.

Rectification Correlation between Water and Ions through Asymmetric Graphene Channels.

Rectification phenomena occurring in asymmetric channels are essential for the design of novel nanofluidic devices such as nanodiodes. Previous studies mostly focus on ion current rectification, while its correlations with water dynamics are rarely explored. In this work, we analyze the transport of water and ions through asymmetric graphene channels under the drive of electric fields using molecular dynamics simulations. A key observation is that the water flux also exists in the rectification phenomenon that follows the ion flux behaviors because of their dynamical coupling relation in electric fields, and both their rectification ratios exhibit maximum behaviors with the change of the channel opening ratio. This is because the ion dehydration is highly asymmetric for small opening ratios. In addition, the cations and anions have distinct rectification ratios that are strongly dependent on the field strength, where the values for anions can even be 1-2 orders larger. This can be attributed to their different hydration shell and dehydration processes in the graphene channel. The translocation time of ions displays a power law relation with the field strength, in agreement with the prediction by Langevin dynamics. Due to the exclude-volume effect, the occupancy of water and ions shows a clear competition and thus changes in an opposite trend with the field strength. Our results demonstrate the rectification correlations between water and ions, and tuning the geometry of graphene channels provides a simple and robust new route to achieve high rectification ratios.

Trace element fingerprints of Ni–Fe–S–As minerals in subduction channel serpentinites

A variety of base-metal minerals (BMM) may form during hydration-dehydration of ultramafic rocks within subduction zones. However, the trace element fingerprints of these minerals and their relation to different stages of the subduction cycle are still unexplored. Here, we present the first comprehensive in situ analysis by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) of (semi)-metals (Ni, Fe, As, Sb, Co, Bi, Te, Pb, Cd, Se, Cu, Zn, and Mn) and precious metals (Os, Ir, Rh, Pt, Pd, Au, and Ag) for Ni–Fe–S–As minerals in subducted serpentinites from the La Cabaña area (South-Central Chile). The targeted rocks are medium- and high-pressure serpentinites recording the entire cycle of burial-exhumation within a subduction zone. A first stage of hydration of upper mantle peridotites within the mantle wedge led to formation of lizardite after magmatic olivine at ~300 °C. This stage was followed by prograde hydration (i.e., antigoritization at ~320–400 °C; <1GPa) and subsequent partial dehydration (formation of prograde olivine at ~600 °C and 1.1 GPa) within the subduction channel, and final exhumation of the serpentinites and incorporation in the accretionary prism still in the stability field of antigorite (>300 °C). The Ni–Fe–S–As minerals in these serpentinites include Ni-Fe-rich sulfides [pentlandite (Ni,Fe)9S8), smythite (Fe9S11), heazlewoodite (Ni3S2), millerite (NiS)], arsenides [orcelite (Ni5-xAs2), nickeline (NiAs) and maucherite (Ni11As8)] and, to a lesser extent, alloy (awaruite, Ni3Fe) and sulfarsenides (gerdorffite, NiAsS). Their abundance, morphology and chemistry strongly vary with the degree of serpentinization and style of deformation of the host rock. Thus, euhedral grains of heazlewoodite ± awaruite ± magnetite formed in equilibrium with lizardite when magmatic olivine was hydrated within the mantle wedge. Once the lizardite-olivine serpentinites were incorporated into the subduction serpentinite channel, the infiltration of hotter (S-As-Sb)-bearing fluids promoted antigoritization under static regime and precipitation of orcelite and pentlandite in equilibrium with antigorite. Channelling of fluids in zones of focussed strain enhanced further antigoritization in some schistose serpentinites at decreasing fO2 and fS2, resulting in the transformation of pentlandite into a second generation of heazlewoodite–awaruite–magnetite. After relic olivine exhaustion, fO2 and fS2 increased promoting the replacement of the secondary heazlewoodite to millerite. No significant variations in terms of trace elements were observed during these mineral replacements associated to hydration upon prograde metamorphism and/or increasing of strain. In contrast, partial dehydration of serpentinites under high-pressure conditions (> 1GPa) generated Ni-rich awaruite in equilibrium with the prograde assemblage antigorite-metamorphic olivine. These awaruites are depleted in trace elements, indicating substantial (semi)-metal and precious metal mobility during high P-T metamorphism within the subduction channel. During the final stage of deformation linked to exhumation inside the accretionary prism some orcelite grains formed during early antigoritization recrystallized without substantial change in trace element concentration. At this stage, nickeline singularly enriched in gold formed in equilibrium with the recrystallizing orcelite. These results demonstrate that Ni–Fe–S–As minerals formed or modified during the entire subduction cycle of upper mantle rocks have their own characteristic trace element signature (i.e., depletion in precious metals and enrichment in As, Sb, Te, Bi and Pb) that distinguish them from magmatic counterparts.

Waste-Derived Green Nanocatalyst for Biodiesel Production: Kinetic-Mechanism Deduction and Optimization Studies

This research focuses on deducing the kinetic mechanism for biodiesel production catalyzed by a CaO nanocatalyst derived from waste cockle shells via thermal hydration–dehydration treatment. In addition, the CaO nanocatalyst preparation method via thermal hydration–dehydration-related parameters (hydration duration, recalcination temperature, and recalcination duration) was studied and optimized. The transesterification reaction catalyzed by the CaO nanocatalyst followed the Langmuir–Hinshelwood kinetic mechanism with surface reaction as the rate-limiting step. The relatively low activation energy (3786.7 J/mol) for a transesterification reaction offered by the CaO nanocatalyst enhanced the reaction rate to 27.3% FAME yield/hr. The optimal conditions for the thermal hydration–dehydration treatment used to develop the nano CaO catalyst were 6 h of hydration duration, 650 °C of recalcination temperature, and 3 h of recalcination duration. Of biodiesel yield, 94.13% was obtained at a moderate temperature of 60 °C and 3 h reaction time during the transesterification of palm oil catalyzed by the nano-CaO. SEM, BET, and TPD results proved that the CaO nanocatalyst had a large surface area (13.9113 m2/g) and high pore volume (0.0318 cm3/g) that were rich in active sites (1046.46 μmol CO2/g), and the pore diameter (33.17 nm) was accessible to reactants and products.

The 4Hz mechanical vibration-activated Na/Ca exchange as a quantum-sensitive novel target for pain therapy

ABSTRACT The activation of Na/40Ca exchange in reverse (R) mode leading to neuronal swelling and muscle contraction has been suggested as a mechanism for generation of pain signals. However, the activation of R Na/45Ca exchange, having higher rate than R Na/40Ca exchange, brings to depression of pain sensation, the mechanism of which is not clear. The previous data that the 4 Hz mechanical vibration (MV) has pain-relieving effects by activation of cGMP-dependent Na/Ca exchange in forward (F) mode, which leads to muscle hydration and neuronal dehydration, as in case of R Na/45Ca exchange activation, allow us to suggest that the comparative study of the effects of 4 Hz MV and R Na/45Ca exchange on thermal pain thresholds, tissue hydrations in different experimental conductions will make it possible to evaluate the mechanisms of R Na/45Ca exchange-induced inhibition of pain sensation. The obtained data show that the R Na/45Ca exchange-induced depression of pain sensation is due to high [Ca2+]i–inactivation of Na/K pump which brings to further increase of [Ca2+]i, while 4 Hz MV-activated F Na/Ca exchange-induced pain-relieving effect is due to Na/K pump activation by low [Ca2+]i. It is suggested that the R Na/45Ca exchange inhibits pain sensation, which is due to high [Ca2+]i–induced depression inhibition of muscle contractility, while the 4 Hz MV-induced pain-relieving effect is due to activation of Na/K pump by cGMP-dependent decrease of [Ca2+]i leading to muscle relaxation and neuronal dehydration. Therefore, the 4 Hz MV has been suggested as a novel quantum-mechanical sensitive target for pain therapy.

Transesterification of Sunflower Oil over Waste Chicken Eggshell-Based Catalyst in a Microreactor: An Optimization Study.

The statistical experimental design (DoE) and optimization (Response Surface Methodology combined with Box–Behnken design) of sunflower oil transesterification catalyzed by waste chicken eggshell-based catalyst were conducted in a custom-made microreactor at 60 °C. The catalyst was synthesized by the hydration–dehydration method and subsequent calcination at 600 °C. Comprehensive characterization of the obtained catalyst was conducted using: X-ray powder diffractometry (XRD), X-ray fluorescence (XRF), Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), N2 physisorption, and Hg-porosimetry. Structural, morphological, and textural results showed that the obtained catalyst exhibited high porosity and regular dispersity of plate-like CaO as an active species. The obtained optimal residence time, catalyst concentration, and methanol/oil volume ratio for the continuous reaction in microreactor were 10 min, 0.1 g g−1, and 3:1, respectively. The analysis of variance (ANOVA) showed that the obtained reduced quadratic model was adequate for experimental results fitting. The reaction in the microreactor was significantly intensified compared to a conventional batch reactor, as seen through the fatty acid methyl esters (FAMEs) content after 10 min, which was 51.2% and 18.6%, respectively.

Activation of the G‐Protein‐Coupled Receptor Rhodopsin by Water

AbstractVisual rhodopsin is an important archetype for G‐protein‐coupled receptors, which are membrane proteins implicated in cellular signal transduction. Herein, we show experimentally that approximately 80 water molecules flood rhodopsin upon light absorption to form a solvent‐swollen active state. An influx of mobile water is necessary for activating the photoreceptor, and this finding is supported by molecular dynamics (MD) simulations. Combined force‐based measurements involving osmotic and hydrostatic pressure indicate the expansion occurs by changes in cavity volumes, together with greater hydration in the active metarhodopsin‐II state. Moreover, we discovered that binding and release of the C‐terminal helix of transducin is coupled to hydration changes as may occur in visual signal amplification. Hydration–dehydration explains signaling by a dynamic allosteric mechanism, in which the soft membrane matter (lipids and water) has a pivotal role in the catalytic G‐protein cycle.

Kinetics and Mechanism of the Dehydration of Calcium Sulfate Dihydrate: A Comprehensive Approach for Studying the Dehydration of Ionic Hydrates under Controlled Temperature and Water Vapor Pressure

We studied the kinetics and mechanism of the dehydration reaction of calcium sulfate dihydrate to hemihydrate under controlled temperature and water vapor partial pressure. From kinetic and reactio...

First-principles study of dehydration interfaces between diaspore and corundum, gibbsite and boehmite, and boehmite and γ-Al2O3: Energetic stability, interface charge effects, and dehydration defects

Aluminum hydrate dehydration interfaces were studied using a van der Waals density functional. The interface configurations investigated here as a first exploration of possible interface geometries, were all found to have a reasonable probability of occurring. From gibbsite/boehmite and boehmite/γ-Al2O3 interface simulation cells, the formation of dehydration-related defects during relaxation was observed. H transfer between hydroxyl groups, and separation of hydroxyl groups and H atoms from the lattice, resulted in the formation of chemisorbed H2O and OH2 groups in gibbsite; in boehmite, the formation of OH2 groups and interstitial H was observed. All interfaces show a transfer of small amounts of charge across the interface. Accumulation of charge in spaces interstitial to the lattice was found to play a role in the dehydration process as well. The present study shows the potential of interface studies for elucidating dehydration pathways at the atomic scale, and offers various starting-points for follow-up studies.

Time-Resolved Cooperative Motions in the Solid-State Dehydration of Thymine Hydrate

Many organic compounds can exist in hydrated and anhydrous crystalline forms, each of which exhibits its own different set of physical properties. This makes dehydration–rehydration processes an im...

Evaluation ethylcellulose membrane modified with NaA and NaX zeolites for the dehydration of hydrazine hydrate by pervaporation process

ABSTRACT Polymeric ethylcellulose (EC) membrane modified with NaA and NaX in different zeolite loading (10, 20, 30 and 40 wt%) and used in pervaporation dehydration of hydrazine hydrate. The modified membrane prepared by the solution casting method. Pervaporation experiments were conducted at room temperature. Results have shown which hydrophilicity and pervaporation performance of the neat ethylcellulose membrane was enhanced by the incorporation of zeolite into the polymeric matrix. The pervaporation performance enhancement of the modified membrane can be attributed to its hydrophilic inherent and molecular sieving properties of zeolites. The results showed that increasing the zeolite concentration increases the normal flux of the membrane, but selectivity and Pervaporation Separation Index (PSI) will have a maximum value in 30% of zeolite loading. In addition, the results showed that in equal amounts of zeolite; Membranes containing NaA perform better than membranes containing NaX in the pervaporation process. The highest flux and selectivity are64.761 g/m2.h and 12.368 for NaA-EC respectively. The swelling degree of the modified membrane was investigated by the sorption experiment at room temperature. Mechanical stability tests of membranes show that the mechanical strength of modified membranes improves compared to ethylcellulose polymeric membrane.

Massive Fluid Influx beneath the Colorado Plateau (USA) Related to Slab Removal and Diatreme Emplacement: Evidence from Oxygen Isotope Zoning in Eclogite Xenoliths

Abstract The Colorado Plateau has undergone as much as 1·8 km of uplift over the past 80 Myr, but never underwent the pervasive deformation common in the neighboring tectonic provinces of the western USA. To understand the source, timing and distribution of mantle hydration, and its role in plateau uplift, garnets from four eclogite xenoliths of the Moses Rock diatreme (Navajo Volcanic Field, Utah, USA) were analyzed in situ for δ18O by secondary ion mass spectrometry. These garnets have the largest reported intra-crystalline oxygen isotope zoning to date in mantle-derived xenoliths with core-to-rim variations of as much as 3 ‰. All samples have core δ18O values greater than that of the pristine mantle (∼5·3 ‰, mantle garnet as derived from mantle zircon in earlier work) consistent with an altered upper oceanic crust protolith. Oxygen isotope ratios decrease from core to rim, recording interaction with a low-δ18O fluid at high temperature, probably derived from serpentinite in the foundering Farallon slab. All zoned samples converge at a δ18O value of ∼6 ‰, regardless of core composition, suggesting that fluid infiltration was widely distributed. Constraints on the timing of this fluid influx, relative to diatreme emplacement, can be gained from diffusion modeling of major element zoning in garnet. Modeling using best estimates of peak metamorphic conditions (620 °C, 3·7 GPa) yields durations of &amp;lt;200 kyr, suggesting that fluid influx and diatreme emplacement were temporally linked. These eclogite xenoliths from the Colorado Plateau record extensive fluid influx, pointing to complex hydration–dehydration processes related to flat-slab subduction and foundering of the Farallon plate. Extensive hydration of the lithospheric mantle during this fluid influx may have contributed to buoyancy-driven uplift of the Colorado Plateau and melt-free emplacement of Navajo Volcanic Field diatremes.