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Dialkylmagnesium compounds (MgR2, R = C2H5, C4H9 etc.,) have drawn considerable interest in recent years due to their role in commercial polymerization reactions. Herein, we report a thorough account on the reaction intermediates involved in the synthesis of di-n-butylmagnesium from anhydrous magnesium chloride and n-butyllithium. Energy-dispersive X-ray spectroscopy (EDX) and powder X-ray diffraction (PXRD) were used to characterize the products formed in transmetalation reaction and it supports that the Schlenk equilibrium between the nBuMgCl and nBu2Mg may be operating during the synthesis of di-n-butylmagnesium from anhydrous magnesium chloride. 1,4-Dioxane was used to shift the Schlenk equilibrium to form soluble 1,4-dioxane adduct of di-n-butylmagnesium and insoluble MgCl2 based product. PXRD was used to study the transformation of 1,4-dioxane adduct of di-n-butylmagnesium to pure di-n-butylmagnesium.

The use of proppants, especially larger and more dense proppants, during reservoir stimulation in tight oil and gas plays requires the introduction of highly viscous fluids to transport the proppants (mm–mm) with the fracturing fluid. The highly viscous fluids required result in increased pump loads and energy costs. Furthermore, although proppant deployment with fracturing fluids is a standard practice for unconventional oil and gas stimulation operations, there are only a few examples in the US of the applying proppant technology to geothermal energy production. This is due to proppant dissolution, proppant flowback, and loss of permeability that, although also occurs during unconventional oil/gas stimulation (hydraulic fracturing) operations, it is amplified under the extreme temperatures found in enhanced geothermal systems (EGS). This work demonstrates proof-of-concept of a novel, CO 2 -responsive, lightweight sintered-bauxite/polymer core/shell proppant. The polymer shell has two main roles; (1) increase the stability of the proppant dispersion in water without the addition of rheology modifiers, and (2) once at the fracture network react with CO 2 to promote particle aggregation and prop fractures open. In this work, both roles are demonstrated together with the thermal and chemical stability of the materials showing the potential of these CO 2 -responsive proppants as an alternative proppant technology for geothermal and unconventional oil/gas applications.

Deep underground geologic formations are being evaluated for long-term storage of CO 2 , including large continental flood basalt formations. At the GHGT-11 and GHGT-12 conferences, progress was reported on the initial phases for Wallula Basalt Pilot demonstration test (located in Eastern Washington state), where nearly 1,000 metric tons of CO 2 was injected over a 3-week period during July/August 2013. The target CO 2 injection intervals were two permeable basalt interflow reservoir zones with a combined thickness of ∼20 m that occur within a layered basalt sequence between a depth of 830-890 m below ground surface. During the two-year post-injection monitoring period, downhole fluid samples were periodically collected, coupled with limited wireline borehole logging surveys that provided indirect evidence of on-going chemical geochemical reactions/alterations and CO 2 distribution. A detailed pre-closure field characterization program included downhole fluid sampling, and performance of hydrologic tests and wireline geophysical surveys. Side-wall cores also were retrieved from within the targeted injection zones. Visual observations of the core material identified small globular nodules, translucent to yellow in color, residing within vugs and small cavities, which were not evident in pre-injection side-wall cores obtained from the native basalt formation. Characterization by x-ray diffraction identified these nodular precipitates as ankerite, the identical iron and calcium rich carbonate observed to form in laboratory tests with Columbia River basalts. Isotopic characterization (δ 13 C, δ 18 O) conducted on the ankerite nodules indicate a distinct isotopic signature that is closely aligned with that of the injected CO 2 . Final post-injection wireline geophysical logging results also indicate the presence of free-phase CO 2 at the top of the two injection interflow zones, with no vertical migration of CO 2 above the injection horizons. These findings support previous assumptions regarding storage feasibility and rapid mineralization of CO 2 injected into a suitable basalt formation.

The current study protocol regards a partnered, mixed-methods, cluster-randomized stepped wedge trial of the implementation and effectiveness of the FLOW program. FLOW (not an acronym) is a collection of resources and strategies to assist in determining which recovered or stabilized specialty mental health (SMH) patients should transition back to primary care (PC) and tools to make the transition seamless. Transitioning appropriate patients to PC can increase access and timeliness of mental health care for newly referred mental health patients. Nine sites in one US region will be randomized to one of three waves in which they will receive implementation-facilitation to implement the FLOW program. Primary outcomes will include the reach of FLOW, provider adoption of the program, effectiveness in increasing access in SMH, implementation fidelity, and maintenance over time. A mixed-methods analysis of implementation factors associated with implementation success will also be conducted, including the following as possible predictors: staffing ratios, site resources, leadership and provider support for the program, and local champion characteristics. This study's results will provide evidence for the effectiveness of FLOW in increasing access and may provide generalizable information about characteristics of sites that are likely to be successful with implementing similar programs.

Metal-organic frameworks (MOFs) are one of the widely investigated materials of 21st century due to their unique properties such as structural tailorability, controlled porosity, and crystallinity. These exceptional properties make them promising candidates for various applications including gas adsorption and storage, separation, and catalysis. However, commercial applications of MOFs produced by conventional methods including solvothermal or hydrothermal synthesis are rather limited or restricted because they often produce fine powders. The use of MOF powders for industrial applications often results in pressure drop problems similar to the case with zeolites and limited robustness against water. To realize these materials for practical applications, densification of MOFs (by increasing pellet density) is routinely employed to form pellets, extrudates or beads to improve the overall density, volumetric adsorption, mechanical and thermal properties. However, the improvements come with some drawbacks such as reduction in overall porosity, surface area, and gravimetric adsorption capacity. Thus, optimizing the properties of densified MOF's by tuning the pellet density is very crucial for realizing these materials for industrial applications. Methods that increase the packing density in MOFs (for example by intentional interpenetration, etc.), which is different from pellet density, is not the scope of this review. In this review, the properties and applications of densified MOFs with different metal clusters and organic linkers are discussed.

Objective To examine the relationship between executive dysfunction, as a multidimensional construct (ie, decision-making, impulsivity, aggression, concept formation), and suicide attempt (SA) history in a high-risk sample of veterans with moderate to severe traumatic brain injury (TBI). Design Observational, 2×2 factorial design. To estimate group differences, linear regression was used to model the primary and secondary outcomes of interest as a function of history of SA, TBI, and the interaction between the 2 variables. Additionally, to determine the pattern of performance over the course of the Iowa Gambling Test (IGT), scores were modeled across the 5 IGT blocks by using a varying-coefficient model. Setting Veterans Health Administration. Participants Veterans (N=133; no SA/no TBI, n=48; no SA/yes TBI, n=51; yes SA/no TBI, n=12; yes SA/yes TBI, n=22) completed the study measures. Interventions Not applicable. Main Outcome Measures IGT, Immediate and Delayed Memory Test, State-Trait Anger Expression Inventory-2, Wisconsin Card Sorting Test. Results All groups demonstrated learning over the course of the IGT, except for veterans with a history of both SA and TBI. No group differences were identified on other measures of executive functioning. Conclusions These findings highlight the potential, unique decision-making challenges faced by veterans with a history of TBI and SA. Specialized interventions focused on overall distress reduction and means restriction may be required to prevent future self-directed violence.

Expandable clays such as montmorillonite have interlayer exchange sites whose hydration state can be systematically varied from near anhydrous to almost bulk-like water conditions. This phenomenon has new significance with the simultaneous implementation of geological sequestration and secondary utilization of CO2 to both mitigate climate warming and enhance extraction of methane from hydrated clay-rich formations. In this study, the partitioning of CO2 and H2O between Na-, Ca-, and Mg-exchanged montmorillonite and variably hydrated supercritical CO2 (scCO2) was investigated using in situ X-ray diffraction (HXRD), infrared (IR) spectroscopic titrations, and quartz crystal microbalance (QCM) measurements. Density functional theory calculations provided mechanistic insights. Structural volumetric changes were correlated to quantified changes in sorbed H2O and CO2 concentrations as a function of percent H2O saturation in scCO2. Intercalation of CO2 is inhibited when the clay is fully collapsed (dehydrated interlayer), peaks sharply with the introduction of some H2O and partial expansion of the interlayer region, and then decreases systematically with further hydration of the clay. This behavior is discussed in the context of recent theoretical calculations of the montmorillonite H2O–CO2 system.

Basalt samples representing five different formations were immersed in water equilibrated with supercritical carbon dioxide containing 1% hydrogen sulfide (H2S) at reservoir conditions (100 bar, 90 °C) for up to 3.5 years. Surface coatings in the form of pyrite and metal cation substituted carbonates were identified as reaction products associated with all five basalts. In some cases, high pressure tests contained excess H2S, which produced the most corroded basalts and largest amount of secondary products. In comparison, tests containing limited amounts of H2S appeared least reacted with significantly less concentrations of reaction products. In all cases, pyrite appeared to precede carbonation, and in some instances, was observed in the absence of carbonation such as in cracks, fractures, and within the porous glassy mesostasis. Armoring reactions from pyrite surface coatings observed in earlier shorter duration tests were found to be temporary with carbonate mineralization observed with all the basalts tested in these long duration experiments. Geochemical simulations conducted with the geochemical code EQ3/6 accurately predicted early pyrite precipitation followed by formation of carbonates. Reactivity with H2S was correlated with measured Fe(II)/Fe(III) ratios in the basalts with more facile pyrite formation occurring with basalts containing more Fe(III) phases. These experimental and modeling results confirm potential for long term sequestration of acid gas mixtures in continental flood basalt formations.

Subsurface injection of CO2 is commonplace in certain industries, yet deployment at the scale required for emission reduction is unprecedented and therefore requires a high degree of predictability. Accurate modeling of subsurface geochemical processes related to geologic carbon sequestration requires experimentally derived data for mineral reactions. Most work in this area has focused on aqueous-dominated systems in which dissolved CO2 reacts to form crystalline carbonate minerals. Comparatively little laboratory research has been conducted on reactions occurring between minerals in the host rock and the wet supercritical fluid phase. We studied the carbonation of wollastonite [CaSiO3] exposed to variably hydrated supercritical CO2 (scCO2) at 50, 55 and 70 °C and 90, 120 and 160 bar. Reactions were followed by three novel in situ high pressure techniques, which demonstrated increased dissolved water concentrations in the scCO2 resulted in increased wollastonite carbonation approaching ∼50 wt.%. Overall, the X-ray diffraction and infrared and magic angle nuclear magnetic resonance spectroscopies experiments conducted in this study allow detailed examination of mechanisms impacting carbonation rates. These include the development of amorphous passivating layers, thin liquid water films, and amorphous hydrated carbonate phases. Collectively, these results emphasize the importance of understanding geochemical processes occurring in wet scCO2 fluids.

Near-infrared (NIR) spectroscopy was applied to investigate the dissolution and chemical interaction of water dissolved into supercritical carbon dioxide (scCO2) and the influence of CaCl2 in the co-existing aqueous phase at fo empe e : 40 50 75 nd 100 C at 90 atm. Consistent with the trend of the vapor pressure of water, the solubility of pure water in scCO2 inc e ed f om 40 °C (0.32 mole%) o 100 °C (1.61 mole%). The presence of CaCl2 negatively affects the solubility of water in scCO2: at a given temperature and pressure the solubility of water decreased as the concentration of CaCl2 in the aqueous phase increased, following the trend of the activity of water. A 40 °C, the water concentration in scCO2 in contact with saturated CaCl2 aqueous solution was only 0.16 mole%, a drop of more than 50% as compared to pure water while that a 100 °C was 1.12 mole%, a drop of over 30% as compared to pure water, under otherwise the same conditions. Analysis of the spectral profiles suggested that water dissolved into scCO2 exists in the monomeric form under the evaluated temperature and pressure conditions, for both neat water and CaCl2 solutions. However,more » its rotational degrees of freedom decrease at lower temperatures due to higher fluid densities, leading to formation of weak H2O:CO2 Lewis acid-base complexes. Similarly, the nearly invariant spectral profiles of dissolved water in the presence and absence of saturated CaCl2 under the same experimental conditions was taken as evidence that CaCl2 dissolution in scCO2 was limited as the dissolved Ca2+/CaCl2 would likely be highly hydrated and would alter the overall spectra of waters in the scCO2 phase.« less

The uptake of (18)O by scC(16)O(2) in mixtures containing liquid H(2)(18)O was followed with Raman spectroscopy using a specially designed high-pressure optical cell. Characteristic bands from the C(16)O(18)O and C(18)O(2) molecules were identified in the supercritical phase and measured in the spectra as a function of time after introducing the liquid H(2)(18)O into the scC(16)O(2). Temporal dependence indicated the process was diffusion-limited in our cell for both C(16)O(18)O and C(18)O(2). The ratio of concentrations of the (18)O-labeled CO(2) molecules, C(18)O(2)/C(16)O(18)O, was much higher than a random distribution of the isotopes for the system expected at equilibrium. The results are consistent with previous studies showing both rapid kinetics for oxygen exchange in aqueous solutions and the role of CO(2) transport at liquid water interfaces. More importantly, they demonstrate the potential for using Raman spectroscopy with (18)O isotopic labeling in scCO(2) reaction studies with the recently determined frequency and intensity characteristics of the Fermi dyad peaks from (18)O-containing CO(2) molecules.

Reactions involving supercritical carbon dioxide (scCO 2 ) and a calcium saturated dioctahedral smectite (Ca-STX-1) were examined by in situ high-pressure X-ray diffraction over a range of temperatures (50–100 °C) and pressures (90, 125, and 180 bar) relevant to long-term geologic storage of CO 2 . Exposure of Ca-STX-1 containing one water of hydration (1 W) to anhydrous scCO 2 at 50 °C and 90 bar produced an immediate increase of ∼0.8 A in the d 0 0 1 basal reflection that was sustained for the length of the experiment (∼44 h). Higher ordered basal reflections displayed similar shifts. Following depressurization, positions of basal reflections and FWHM values ( d 0 0 1 ) returned to initial values, with no measurable modification to the clay structure or water content. Similar results were obtained for tests conducted at 50 °C and higher pressures (125 and 180 bar). Exposure of Ca-STX-1 containing two waters of hydration (2 W) to scCO 2 resulted in a decrease in the d 0 0 1 reflection from 14.48 A to 12.52 A, after pressurization, indicating a partial loss of interlayer water. In addition, the hydration state of the clay became more homogeneous during contact with anhydrous scCO 2 and after depressurization. In the presence of scCO 2 and water, the clay achieved a 3 W hydration state, based on a d 0 0 1 spacing of 18.8 A. In contrast to scCO 2 , comparable testing with N 2 gas indicated trivial changes in the d 0 0 1 series regardless of hydration state (1 W or 2 W). In the presence of free water and N 2 , the basal spacing for the Ca-STX-1 expanded slightly, but remained in the 2 W hydration state. The experiments show that potential collapse or expansion of the interlayer spacing depends on the initial hydration state of the clay and scCO 2 , where 1 W clay is stable but ≥2 W layer clay loses water when exposed to anhydrous CO 2 . Consequently, the implications of this study depend upon the depth of the caprock. If the caprock is quite deep, then the 1 W hydration state is favored and the introduction of dry CO 2 could actually help seal the formation. If the caprock is located closer to the surface where 2 W or 3 W montmorillonite is the predominant form then the introduction of dry CO 2 should result in the creation of permeability. Further, these experiments indicate that scCO 2 can become intercalated within hydrated clays under conditions proposed for geologic storage of CO 2 and act as secondary CO 2 traps.

Understanding mechanisms and kinetics of mineral carbonation reactions relevant to sequestering carbon dioxide as a supercritical fluid (scCO2) in geologic formations is crucial to accurately predicting long-term storage risks. Most attention so far has been focused on reactions occurring between silicate minerals and rocks in the aqueous dominated CO2-bearing fluid. However, water-bearing scCO2 also comprises a reactive fluid, and in this situation mineral carbonation mechanisms are poorly understood. Using in situ high-pressure X-ray diffraction, the carbonation of brucite [Mg(OH)2] in wet scCO2 was examined at pressure (82 bar) as a function of water concentration and temperature (50 and 75 °C). Exposing brucite to anhydrous scCO2 at either temperature resulted in little or no detectable reaction over three days. However, addition of trace amounts of water resulted in partial carbonation of brucite into nesquehonite [MgCO3·3H2O] within a few hours at 50 °C. By increasing water content to well above the saturation level of the scCO2, complete conversion of brucite into nesquehonite was observed. Tests conducted at 75 °C resulted in the conversion of brucite into magnesite [MgCO3] instead, apparently through an intermediate nesquehonite step. Raman spectroscopy applied to brucite reacted with 18O-labeled water in scCO2 show it was incorporated into carbonate at a relatively high concentration. This supports a carbonation mechanism with at least one step involving a direct reaction between the mineral and water molecules without mediation by a condensed aqueous layer.

Long term storage of CO2 in geologic formations is currently considered the most attractive option to reduce greenhouse gas emissions while continuing to utilize fossil fuels for energy production. Injected CO2 is expected to reside as a buoyant water-saturated supercritical fluid in contact with reservoir rock, the caprock system, and related formation waters. As reported by McGrail et al., experiments with basalts demonstrated surprisingly rapid carbonate mineral formation occurring with samples suspended in the supercritical CO2 (sc CO2) phase. Those experiments were limited to a few temperatures and CO2 pressures representing relatively shallow ( ≈ 1 k m ) reservoir depths. Because continental flood basalts can extend to depths of 5 km or more, in this paper we extend the earlier results across a pressure-temperature range representative of these greater depths. Different basalt samples, including well cuttings from the borehole used in a pilot-scale basalt sequestration project (Eastern Washington, U.S.) and core samples from the Central Atlantic Magmatic Province, were exposed to aqueous solutions in equilibrium with sc CO2 and water-rich sc CO2 at six different pressures and temperatures for select periods of time (30 to 180 days). Conditions corresponding to a shallow injection of CO2 (7.4 MPa, 34 °C) indicate limited reactivity with basalt; surface carbonate precipitates were not easily identified on post-reacted basalt grains. Basalts exposed under identical times appeared increasingly more reacted with simulated depths. Tests conducted at higher pressures (≥12 MPa) and temperatures (≥55 °C), reveal a wide variety of surface precipitates forming in both fluid phases. Under shallow conditions tiny clusters of aragonite needles began forming in the wet sc CO2 fluid, whereas in the CO2 saturated water, cation substituted calcite developed thin radiating coatings. Although these types of coatings were sparse, conditions corresponding to deeper depths showed increasing carbonate precipitation. Basalts exposed to aqueous dissolved CO2 (25.5 MPa, 116 °C) for 30 days were coated in tiny nodules of precipitate (∼100 μm in diameter) that were identified by micro x-ray diffraction as ankerite, [Ca(Fe,Mg)(CO3)2], a variety of dolomite commonly associated with hydrothermal and metamorphic environments. Surface characterization by SEM revealed well-developed round nodules composed of discrete individual platelets. In contrast, reaction products forming on the basalt in the corresponding wet sc CO2 phase had completely different morphology, appearing in an optical microscope as a surface coating instead of discrete nodules. Examination by SEM revealed layers of discrete platelets forming a cover over a few discrete nodules. Longer test durations (180 days) produced severe iron staining along with minerals structures similar to rhodochrosite and kutnohorite. These preliminary experiments show strong evidence of the faster rate of increase in mineralization reactions taking place in the sc CO2 phase, transformation reactions that are just beginning to be explored in detail.