Limited Dissolution Research Articles

Uranium Repartitioning during Microbial Driven Reductive Transformation of U(VI)-Sorbed Schwertmannite and Jarosite.

This study exposes U(VI)-sorbed schwertmannite and jarosite to biotic reductive incubations under field-relevant conditions and examines the changes in aqueous and solid-phase speciation of U, Fe, and S as well as associated microbial communities over 180 days. The chemical, X-ray absorption spectroscopy, X-ray diffraction, and microscopic data demonstrated that the U(VI)-sorbed schwertmannite underwent a rapid reductive dissolution and solid-phase transformation to goethite, during which the surface-sorbed U(VI) was partly reduced and mostly repartitioned to monomeric U(VI)/U(IV) complexes by carboxyl and phosphoryl ligands on biomass or organic substances. Furthermore, the microbial data suggest that these processes were likely driven by the consecutive developments of fermentative and sulfate- and iron- reducing microbial communities. In contrast, the U(VI)-sorbed jarosite only stimulated the growth of some fermentative communities and underwent very limited reductive dissolution and thus, remaining in its initial state with no detectable mineralogical transformation and solid-phase U reduction/repartitioning. Accordingly, these two biotic incubations did not induce increased risk of U reliberation to the aqueous phase. These findings have important implications for understanding the interactions of schwertmannite/jarosite with microbial communities and colinked behavior and fate of U following the establishment of reducing conditions in various acidic and U-rich settings.

Pulmonary delivery of forsythin-phospholipid complexes improves the lung anti-inflammatory efficacy in mice by enhancing dissolution and lung tissue affinity

Forsythin, currently in phase II clinical trials in China for the treatment of the common cold and influenza, faces challenges in achieving adequate lung drug exposure due to its limited dissolution and permeability, thereby restricting its therapeutic efficacy. The objective of this work was to formulate a forsythin-phospholipid complex (FPC) to enhance its dissolution properties and lung affinity with a particular view to improving pulmonary drug exposure and anti-inflammatory response. The results revealed that forsythin reacted with dipalmitoyl-phosphatidylcholine to form a stable, nanosized FPC suspension. This formulation significantly improved the in vitro drug's dissolution, cellular uptake, and lung affinity compared to its uncomplexed form. Intratracheal administration of FPC in a mouse model of acute lung injury induced by lipopolysaccharide (LPS) resulted in a substantial increase in drug exposure to lung tissues (39.6-fold) and immune cells in the epithelial lining fluid (198-fold) compared to intraperitoneal injection. In addition, FPC instillation exhibited superior local anti-inflammatory effects, leading to improved survival rates among mice with LPS-induced acute respiratory distress syndrome, outperforming both instilled forsythin and injected FPC. Overall, this work demonstrated the potential of phospholipid complexes as a viable option for developing inhalation products for drugs with limited solubility and permeability properties.

Limited dissolution of transition metals in the nanocrystalline cerium (IV) oxide

Nanocrystalline cerium (IV) oxides doped with transition metals have gained significant interest recently, mostly in the field of catalysis. Herein, we present the comprehensive studies on ceria doped with 10 mol.% of transition metals (Mn, Fe, Co, Ni or Cu) synthesized by the reverse microemulsion method. The aim of this work is to study the properties of those materials with the use of different complementary methods like XRD, SEM, TPR, and XPS and to determine the possibility of fabrication of single-phase materials with that doping level. Studies presented here prove that despite showing single-phase XRD patterns with high nanocrystallinity, in all obtained materials, the dopants are not fully incorporated in the ceria lattice. Spectroscopy studies show that additional transition metal oxides are present on the surface of all materials. Herein, we also present the analyses of L3,2-edges of transition metals in ceria, as well as high energy Ce K-edge to prove that 10 mol.% of any of those transition metals cannot be incorporated in the ceria host without the formation of additional phases. Using techniques presented here, it was found that the highest share of Mn can be dissolved in the lattice, while Cu is mostly present as a surficial Cu2O. Studies presented are an important contribution to the discussion about the solubility limits in nanocrystalline ceria and its properties which may be utilized for e.g various catalysts or as electrolytes.

Microwave-assisted alkaline fusion followed by water-leaching for the selective extraction of the refractory metals tungsten, niobium and tantalum from low-grade ores and tailings

The refractory metals tungsten, tantalum and niobium are considered critical raw materials in Europe. Diversifying the supply of such materials, for instance by recovering refractory metals from local low-grade ore materials could reduce their supply risks. However, the extraction processes require to be efficient with a low energy and material consumption and a minimal environmental impact. In this work, microwave (MW) assisted alkaline fusion was explored to extract tungsten from scheelite containing ore materials with different grades (high to very low) and tantalum and niobium from a columbite-tantalite [(Fe,Mn)(Nb,Ta)2O6] concentrate. During the fusion process scheelite was converted into soluble alkali tungstate salts [Na2WO4, K2WO4 and/or K3Na(WO4)2] and the reaction temperature could be lowered to 150–200 °C by fusion with a low-melting eutectic alkali salt system of an 1:1 (m/m) NaOH:KOH mixture. The application of MW-assisted heating allowed for fast and volumetric heating, thereby lowering reaction times to 10 min – 30 min. After fusion, tungsten was extracted by a simple water leaching step leading to extraction efficiencies ranging from 77 % to 97 %. Noteworthily, also P, S and As, which all form soluble oxyanions were extracted from the studied materials. Extraction of niobium and tantalum was also achieved though MW-assisted alkaline fusion as an alternative to acidic fluorine-based hydrometallurgical processes. MW-assisted heating allowed for a fast conversion of the (Fe,Mn)(Nb,Ta)2O6 into alkali tantalate and niobate salts. Under optimal conditions, MW-assisted fusion with KOH (salt:sample = 3:1 (m/m)) at 400 °C for 10 min leached ca. 74 %–88 % of tantalum and 77 %–86 % of niobium into water (L/S=10) at 40 °C for 120 min, while the main matrix elements Mn and Fe displayed limited dissolution (<4%). Due to the low solubility of sodium tantalate and niobate salts in water, MW-assisted alkaline fusion in an eutectic NaOH:KOH mixture followed by water leaching was not efficient.

Selective recovery of antimony from Sb-bearing copper concentrates by integration of alkaline sulphide leaching solutions and microwave-assisted heating: A new sustainable processing route

The technical feasibility of leaching antimony from an antimony-bearing copper sulphide concentrate, using alkaline sulphide solutions and microwave-assisted and non-assisted heating technology, is investigated at a laboratory scale. The leaching test examines the influence of selective leaching reagent (Na2S and NaOH) concentrations, solid/liquid ratio, and temperature. The results indicate that antimony dissolution is highly selective (e.g. only Sb and As are leached), depending on the concentrations of leaching reagents and the leaching temperature. The influence of temperature on the mineral's dissolution, in the range 25–140 °C, is analysed from a thermochemical point of view using equilibrium databases. Under the optimal conditions: leaching agent: 250 g/L Na2S, 60 g/L NaOH, 2 h, 140 °C, with microwave assisted, the leaching efficiency of Sb reached 95.7 %. The antimony content in the copper concentrate is successfully reduced from 1.1 wt% to <0.2 wt% Sb, making it suitable for copper concentrate metallurgical processing. The study demonstrates that increasing temperature and NaOH/Na2S concentrations collectively enhance leaching efficiency, with a statistical significance, reducing both leaching time and the required temperature, compared to non-microwave-assisted leaching. Furthermore, it is established that excess free hydrogen sulphide ions ensure the efficient dissolution of the main impurities associated with penalties, such as antimony and arsenic, with limited copper and iron dissolution from the copper concentrate, predominantly chalcopyrite. Finally, an integrated hydrometallurgical process flowsheet for antimony removal and recovery from a sulphide copper concentrate is proposed.

Hydroxide and Hydronium Ions Modulate the Dynamic Evolution of Nitrogen Nanobubbles in Water.

It has been widely recognized that the pH environment influences the nanobubble dynamics and hydroxide ions adsorbed on the surface may be responsible for the long-term survival of the nanobubbles. However, understanding the distribution of hydronium and hydroxide ions in the vicinity of a bulk nanobubble surface at a microscopic scale and the consequent impact of these ions on the nanobubble behavior remains a challenging endeavor. In this study, we carried out deep potential molecular dynamics simulations to explore the behavior of a nitrogen nanobubble under neutral, acidic, and alkaline conditions and the inherent mechanism, and we also conducted a theoretical thermodynamic and dynamic analysis to address constraints related to simulation duration. Our simulations and theoretical analyses demonstrate a trend of nanobubble dissolution similar to that observed experimentally, emphasizing the limited dissolution of bulk nanobubbles in alkaline conditions, where hydroxide ions tend to reside slightly farther from the nanobubble surface than hydronium ions, forming more stable hydrogen bond networks that shield the nanobubble from dissolution. In acidic conditions, the hydronium ions preferentially accumulating at the nanobubble surface in an orderly manner drive nanobubble dissolution to increase the entropy of the system, and the dissolved nitrogen molecules further strengthen the hydrogen bond networks of systems by providing a hydrophobic environment for hydronium ions, suggesting both entropy and enthalpy effects contribute to the instability of nanobubbles under acidic conditions. These results offer fresh insights into the double-layer distribution of hydroxide and hydronium near the nitrogen-water interface that influences the dynamic behavior of bulk nanobubbles.

Experimental Study on Oil-Gas Interaction Mechanism during Offshore Heavy Oil Gas Injection.

Offshore heavy oil injection gas extraction is a highly scrutinized area in today's petroleum industry. However, the interaction mechanisms between oil and gas are not clear. To elucidate these mechanisms, an indoor experimental setup was established for research purposes. The effects of different types of gases on heavy oil expansion, mass transfer mechanisms between gas and heavy oil, the influence of gas injection on heavy oil phase behavior, and the testing of minimum miscibility pressures are investigated in this study. The results indicate that CO2 yields the best reduction in the heavy oil viscosity. Both forward and backward multiple contact mass transfer processes demonstrate nonmiscible multiple contact dynamic displacement mechanisms involving CO2 dissolution and condensation, as well as C1 extraction and coextraction. Nonmiscible multiple contact dynamic displacement of natural gas primarily involves limited dissolution and condensation of light hydrocarbon components and intermediate hydrocarbon components, with an extremely weak extraction effect. The minimum miscibility pressures are in the order of CO2 < natural gas < N2. This research provides important experimental evidence and theoretical guidance for further improving offshore heavy oil injection gas technology and practice.

Zircon Zr[sbnd]Hf isotope disequilibrium during crustal anatexis: A record from the Mesozoic migmatite in the eastern Gangdese arc, South Tibet

Stable zirconium (Zr) isotopes have become the focus of attention as potential tracers of magma crystallization and differentiation processes. However, the effects of partial melting, especially disequilibrium melting, on Zr isotope fractionation remain unclear. Here we report in-situ zircon UPb ages, major and trace elements, and ZrHf isotope data for the migmatites in the eastern Gangdese arc, South Tibet. The leucosomes from the metatexite and diatexite migmatites are generally concordant with the foliation of the paleosome and display diffuse and gradational contacts with the melanosomes, indicating that they are in-source leucosomes. Zircon in the paleosome, the protolith of the migmatites, have UPb age of 361 ± 2 Ma and low 176Hf/177Hf ratios of 0.282399–0.282482. They exhibit intragrain variation in δ94/90Zr values, increasing from the core (−0.10 ‰ to +0.36 ‰) to the rim (+0.14 ‰ to +0.55 ‰) domains. The negative correlation between δ94/90Zr values and Zr/Hf ratios suggests preferential incorporation of light Zr isotopes during the crystallization of the zircon in the protolith. Most zircon in the leucosomes from the metatexite and diatexite migmatites exhibit distinct overgrowth rims around the inherited cores. The inherited cores have consistent UPb ages (ca. 360 Ma), trace elements, and Hf isotopic compositions (0.282362–0.282449) with zircon in the paleosome, indicating in situ partial melting. The inherited cores display δ94/90Zr values ranging from −0.12 ‰ to +0.31 ‰, consistent with the zircon core domains in the paleosome. The overgrowth rims have UPb ages of ca. 102 Ma and display higher 176Hf/177Hf ratios (0.282592–0.282900) and δ94/90Zr values (+0.01 ‰ to +0.63 ‰) than their inherited cores. The elevated 176Hf/177Hf for the overgrowth rims resulted from the retention of unradiogenic 177Hf in the residue due to limited zircon dissolution and more release of radiogenic 176Hf to the melts because of the garnet breakdown, indicating disequilibrium melting. The elevation of δ94/90Zr for the overgrowth rims relative to the inherited cores was not caused by the disequilibrium melting of other Zr-bearing minerals but was mainly controlled by the Zr isotopic composition and dissolution degree of the zircon in the protolith. The preferential melting of isotopically heavy zircon rims would elevate the δ94/90Zr values in the melts relative to their zircon-bearing protoliths. Crustal anatexis may be another important mechanism contributing to the Zr isotope fractionation during crustal differentiation.

Rheological properties of magnesium bentonite and sepiolite suspensions after dynamic ageing at high temperatures

Abstract The rheological properties of three Na-activated, trioctahedral Mg-bentonites (hectorite clay from the CMS Source Clay Project repository, saponite clay from Spain and stevensite clay from Rhassoul, Morocco) and a sepiolite clay from Greece were examined after dynamic ageing at temperatures up to 230°C. The 5% w/v suspensions were prepared by dispersing the clay mineral samples in distilled water. The suspensions underwent dynamic, thermal ageing for 16 h before determination of the viscosity, filtration loss, filter cake thickness and pH and the concentration of dissolved Na+ and Mg2+. Thermal ageing contributed to the dispersion of clay particles, with a direct effect on plastic and apparent viscosity, introducing pseudoplastic behaviour. With the exception of the stevensite clay at 230°C that displayed limited dissolution at 230°C and partial conversion to kerolite, the clays were stable at high temperatures. The Na-activation of all clays except for stevensite was not adversely affected by thermal ageing. Thermal ageing of stevensite at 230°C facilitated Na exchange and yielded suspension with high viscosity and low filtrate loss. Only the suspensions of hectorite and those of stevensite aged at 230°C met with American Petroleum Institute specifications. The thermal behaviour and rheological properties of the clays might be interpreted according to the intrinsic properties of the clay minerals, such as layer charge and charge distribution.

Beyond the Surface: A Methodological Exploration of Enzyme Impact along the Cellulose Fiber Cross-Section.

Despite the wide range of analytical tools available for the characterization of cellulose, the in-depth characterization of inhomogeneous, layered cellulose fiber structures remains a challenge. When treating fibers or spinning man-made fibers, the question always arises as to whether the changes in the fiber structure affect only the surface or the entire fiber. Here, we developed an analysis tool based on the sequential limited dissolution of cellulose fiber layers. The method can reveal potential differences in fiber properties along the cross-sectional profile of natural or man-made cellulose fibers. In this analytical approach, carbonyl groups are labeled with a carbonyl selective fluorescence label (CCOA), after which thin fiber layers are sequentially dissolved with the solvent system DMAc/LiCl (9% w/v) and analyzed with size exclusion chromatography coupled with light scattering and fluorescence detection. The analysis of these fractions allowed for the recording of the changes in the chemical structure across the layers, resulting in a detailed cross-sectional profile of the different functionalities and molecular weight distributions. The method was optimized and tested in practice with LPMO (lytic polysaccharide monooxygenase)-treated cotton fibers, where it revealed the depth of fiber modification by the enzyme.

Particulate iron oxide food colorants (E 172) during artificial digestion and their uptake and impact on intestinal cells

Iron oxide of various structures is frequently used as food colorant (E 172). The spectrum of colors ranges from yellow over orange, red, and brown to black, depending on the chemical structure of the material. E 172 is mostly sold as solid powder. Recent studies have demonstrated the presence of nanoscaled particles in E 172 samples, often to a very high extent. This makes it necessary to investigate the fate of these particles after oral uptake. In this study, 7 differently structured commercially available E 172 food colorants (2 x Yellow FeO(OH), 2 x Red Fe2O3, 1 x Orange Fe2O3 + FeO(OH) and 2 x Black Fe3O4) were investigated for particle dissolution, ion release, cellular uptake, crossing of the intestinal barrier and toxicological impact on intestinal cells. Dissolution was analyzed in water, cell culture medium and artificial digestion fluids. Small-angle X-ray scattering (SAXS) was employed for determination of the specific surface area of the colorants in the digestion fluids. Cellular uptake, transport and toxicological effects were studied using human differentiated Caco-2 cells as an in vitro model of the intestinal barrier. For all materials, a strong interaction with the intestinal cells was observed, albeit there was only a limited dissolution, and no toxic in vitro effects on human cells were recorded.

Investigating the Impact of Aqueous Phase on CO2 Huff ‘n’ Puff in Tight Oil Reservoirs Using Nuclear Magnetic Resonance Technology: Stimulation Measures and Mechanisms

Summary CO2 huff ‘n’ puff is a promising enhanced oil recovery (EOR) technique for tight/shale reservoirs, also enabling CO2 geological storage. However, the effectiveness of this method can be significantly affected by the aqueous phase resulting from connate water and hydraulic fracturing. The mechanism underlying the influence of the aqueous phase on oil recovery during CO2 huff ‘n’ puff, as well as the corresponding stimulation methods in such scenarios, remain unclear and warrant further study. To investigate this, we utilized a nuclear magnetic resonance (NMR) instrument to track the movement of fluids during CO2 huff ‘n’ puff under water invasion conditions. The impact of the invaded aqueous phase on oil recovery was examined, and the impact of different treatment parameters was explored. The results show that the aqueous barrier formed by water invasion alters the pathway of CO2 diffusion to matrix oil. This alteration leads to a diminished concentration of CO2 in the oil phase, which, in turn, results in a substantial reduction in oil recovery. Consequently, the performance of CO2 huff ‘n’ puff is highly sensitive to the water phase. Nevertheless, the oil recovery dynamics in cyclic CO2 huff ‘n’ puff under water invasion exhibit distinctive patterns compared with those without water invasion. These differences manifest as notable low oil recovery in the first cycle, followed by a rapid increase in the second cycle. This behavior primarily arises from the expulsion of a significant portion of the invaded water from the macropores after the first cycle. However, the effectiveness of this mechanism is limited in micropores due to the challenging displacement of trapped water in such pores. Raising the injection pressure mainly boosts oil recovery in macropores, with minimal response in micropores. Yet, the achievement of miscibility does not lead to a substantial improvement in the CO2 huff ‘n’ puff performance, primarily due to the constraints imposed by the limited CO2 dissolution through molecular diffusion Additionally, we have proposed three stimulation mechanisms achieved by lengthening the soaking time under water invasion conditions. First, the prolonged soaking time increases the concentration of CO2 molecules that diffuse into the matrix oil. Second, it promotes the imbibition of the trapped water on the fracture surface into the deeper matrix to alleviate water blockage. Finally, the invaded water in macropores displaces oil in micropores by capillary force during the soaking period.

PRE‐, SYN‐ AND POST‐TECTONIC DIAGENETIC EVOLUTION OF A CARBONATE RESERVOIR: A CASE STUDY OF THE LOWER CRETACEOUS FAHLIYAN FORMATION IN THE DEZFUL EMBAYMENT, ZAGROS FOLDBELT, SW IRAN

Lower Cretaceous carbonates of the Fahliyan Formation form prolific reservoir rocks at oilfields in the Dezful Embayment, central Zagros fold‐thrust belt, SW Iran. The carbonates have undergone significant diagenetic alteration in phases which can in general be linked to the pre‐, syn‐ and post‐tectonic evolution of the fold‐thrust belt. This paper investigates the impact of diagenetic processes on the reservoir quality of the carbonates using integrated petrographic, geochemical and sedimentological analyses of subsurface and outcrop samples of the formation. Diagenetic alterations include:(i) pre‐tectonic eogenesis in the marine and shallow‐burial realm, which resulted in micritization of allochems and cementation by equant and isopachous calcite rims and framboidal pyrite together with limited dolomitization and dissolution of metastable bioclasts. The isotopic compositions of micrite and early calcite cement depart from postulated values of Lower Cretaceous marine carbonates, signifying early stabilization of precursor metastable carbonate minerals and the possible effects of the incursion of meteoric waters and/or increasing burial temperatures;(ii) mesogenesis during the subsequent syn‐tectonic phase, which included Late Cretaceous ophiolite obduction at the northern margin of the Arabian Plate and the later Zagros orogeny in the Miocene‐Pliocene. Diagenetic modifications included the emplacement of hydrocarbons, the development of stylolites and fractures, and the precipitation of saddle dolomite, replacive rhombic dolomite, discrete pyrite, microcrystalline quartz, kaolin and anhydrite. The average stable isotope compositions of saddle dolomite (δ18O: ‐6.9 ‰ ± .9 and δ13C 0.5 ‰ ± 1.6, respectively) also reflects the influence of high temprature basinal fluids;and (iii) “late” (telogenetic, post‐tectonic) uplift‐related modification starting in the Pliocene, when the incursion of meteoric waters resulted in the formation of vugs, the calcitization of dolomite, and cementation by fracture‐filling blocky calcite. The negative δ18O and δ13C stable isotope values (average: ‐5.5 ‰ ± 1.5; and ‐3.6 ‰ ± 5.9, respectively) of late blocky calcite cement suggest the incursion of meteoric water into the system.This study demonstrates that diagenetic processes in carbonates in the Fahliyan Formation, which exerted a significant control on the distribution of secondary porosity, can be related to the tectonic evolution of the central Zagros fold‐thrust belt. Thus, constraining the diagenetic history of carbonate successions within the context of their wider tectonic evolution is important for the prediction of the spatial and temporal distribution of reservoir quality.

Potential Dependence of Ir Dissolution Using Time-Resolved Measurements

Electrocatalysis efforts in low temperature, PEM-based electrolysis tend to focus on the oxygen evolution reaction (OER) since it is several orders of magnitude kinetically slower than its counterpart, the hydrogen evolution reaction (HER). 1 In comparison to other OER catalysts, Ir-based metal oxides (IrOx) 2-6 are regarded as the best PEM electrolyzer electrocatalysts as they are both active and are relatively stable.7, 8 However, even Ir-based electrocatalysts slowly undergo dissolution under the operating conditions of the electrolyzer anode. 9-10, 7 Considering the low Earth abundance and high-cost of Ir, understanding the kinetics and mechanism of its electrochemical dissolution is of vital importance to develop strategies targeting high activity, long-term stability, and limited metal dissolution in acidic media. Mechanistic studies of both OER and dissolution at the solid–liquid interface are more challenging, as they typically require detection of reaction intermediates with short lifetimes. An electrochemical cell coupled to a highly-sensitive analytical technique provides a platform for detection of dissolution products and may help to resolve the degradation pathway of Ir and its oxides and the correlation to the OER mechanism.In this work, we aim to understand the structure-durability relation for different Ir oxides. An electrochemical flow cell system connected to an inductively-coupled plasma-mass spectrometer (ICP-MS) capable of detecting trace concentrations (<ppb) of dissolved elements in solution is used to investigate the dissolution processes of Ir from the oxides. The influence of various parameters such as potential, potentiodynamic profile parameters (e.g., scan rate, upper and lower potential limits) and catalyst type, on the dissolution processes in acidic electrolytes at room temperature will be investigated. Fundamental models have been developed to explain the mechanisms of the dissolution processes under various conditions. Moreover, the structural changes before and after catalyst testing will be studied. Further, the electrochemical data combined with the ICP-MS data will be correlated with X-ray absorption spectroscopy (XAS) and small angle X-ray scattering (SAXS) to obtain a comprehensive view of the oxide structure. Acknowledgements This work was supported by the U.S. Department of Energy, Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office (HFTO) under the H2NEW Consortium. This work was authored in part by Argonne National Laboratory, a U.S. Department of Energy (DOE) Office of Science laboratory operated for DOE by UChicago Argonne, LLC under contract no. DE-AC02-06CH11357. References M. Alia, B. Rasimick, C. Ngo, K. C. Neyerlin, S. S. Kocha, S. Pylypenko, H. Xu, B. S. Pivovar, J. Electrochem. Soc., 163, F3105 (2016).M. Alia, M. -A. Ha, G. C. Anderson, C. Ngo, S. Pylypenko, R. E. Larsen, J. Electrochem. Soc., 166, F1243 (2019).Cherevko, S. Geiger, O. Kasian, N. Kulyk, J. P. Grote, A. Savan, B. R. Shrestha, S. Merzlikin, B. Breitbach, A. Ludwig, et al., Catal. Today, 262, 170 (2016).Lee, J. Suntivich, K. J. May, E. E. Perry, Y. Shao-Horn, J. Phys. Chem. Lett., 3, 399 (2012).F. Abbott, D. Lebedev, K. Waltar, M. Povia, M. Nachtegaal, E. Fabbri, C. Copéret, T. J. Schmidt, Chem. Mater., 28, 6591 (2016).N. Nong, T. Reier, H.-S. Oh, M. Gliech, P. Paciok, T. H. T. Vu, D. Teschner, M. Heggen, V. Petkov, R. Schlögl, et al., Nat. Catal. , 1, 841(2018).Danilovic, R. Subbaraman, K.-C. Chang, S. H. Chang, Y. J. Kang, J. Snyder, A. P. Paulikas, D. Strmcnik, Y.-T. Kim, and D. Myers, J. Phys.Chem. Lett., 5, 2474 (2014).Reier, M. Oezaslan, and P. Strasser, ACS Catalysis, 2, 1765 (2012).Cherevko, S. Geiger, O. Kasian, N. Kulyk, J.-P. Grote, A. Savan, B. R. Shrestha, S. Merzlikin, B. Breitbach, A. Ludwig, K. J. J. Mayrhofer, Catal. Today, 262, 170 (2016).Kasian, S. Geiger, P. Stock, G. Polymeros, B. Breitbach, A. Savan, A. Ludwig, S. Cherevko, K. J. J. Mayrhofer, J. Electrochem. Soc., 163, F3099 (2016).

Understanding the microstructure and mechanical performance of heat-treated Inconel 625/TiC composite produced by laser powder bed fusion

This work aims to develop and characterize Inconel 625 (IN625) reinforced with 1 wt% of sub-micrometric TiC particles processed by the Laser Powder Bed Fusion (LPBF) process. The effect of TiC particles on the IN625 alloy was investigated in the as-built and two heat-treated conditions. A volumetric energy density of 99 J/mm3 could produce bulk IN625 and IN625/TiC samples with residual porosity less than 0.15%. The as-built IN625 and IN625/TiC showed columnar grains along the building direction and sub-micrometric dendritic architectures. The as-built IN625/TiC presented higher hardness, tensile strength, and similar elongation at failure with respect to the as-built IN625 alloy. These mechanical properties are mainly attributed to the reinforcement effect of the TiC particles predominantly located along the grain boundaries, melt pool contours, and interdendritic areas. After heat treatments at 980 °C and 1150 °C, the IN625 alloy and IN625/TiC composite presented different microstructure stability and mechanical properties evolution, revealing greater hardness and tensile strength for the composite. In particular, when heat-treated, the IN625 was subjected to a remarkable dendritic dissolution at 980 °C and recrystallization at 1150 °C. Conversely, the IN625/TiC revealed a limited dendritic dissolution at 980 °C and the inhibition of recrystallization at 1150 °C. Overall, the pinning effect of the TiC particles was effective in providing less microstructure and mechanical properties variations under heat treatments. The current work describes the effect of adding TiC particles on the microstructure stabilization and mechanical properties evolution of additively processed LPBFed IN625 alloy in as-built and heat-treated conditions.

Regional variation of evaporite diagenesis in Xingouzui sandstones in Jianghan Basin, China: Implications for the evolution and prediction of saline reservoirs’ quality

Diagenetic processes and associated pore evolution are essential factors that control the development and distribution of porosity and permeability in saline reservoirs. The goal of this study is to systematically describe the comparative diagenetic processes, porosity evolution, and diagenetic facies of sandstone reservoirs in the Eocene Lower Xingouzui Formation (LXF) in two depressions in the Jianghan Basin, China. To achieve these goals, an integrated approach of petrographic, mineralogical, geochemical, and petrophysical analyses such as thin-section observations, X-ray diffraction (XRD), and mercury intrusion porosimetry (MIP) was applied to sandstone samples obtained from the Qianjiang and Jiangling sags. Diagenetic studies showed that the LXF samples had experienced several phases of diagenesis, including compaction, non-ferroan carbonate/sulfate cementation, feldspar and carbonate dissolution, quartz overgrowth cementation, ferroan carbonate and sulfate cementation, cubic pyrite precipitation, and limited gypsum dissolution. Although the LXF samples from both the Qianjiang and Jiangling sags experienced a noticeable porosity reduction induced by the compaction, the differences in diagenesis between these two sags were primarily due to complex and diverse cementation types. For instance, both early carbonate and sulfate cementation were recognized in Qianjiang samples, while only early carbonate cements were present in Jiangling samples. Based on a quantitative evaluation of the relative importance of diagenetic processes, diagenetic facies were defined in the LXF sandstones. Additionally, the pore evolution study indicated that two (upper and lower) zones of abnormally high porosity and permeability (AHPP) were developed in both sags. In particular, the upper AHPP zones occurred in sandstones in the Qianjiang and Jiangling depressions at depths of 1300 and 1800 m, respectively, while the lower AHPP zones in both depressions were located at a depth of 3300 m. The differences in the development mechanisms between the upper and lower AHPP zones were determined. This work provides an overview of the evolution and evaluation of sulfate- and carbonate-bearing sandstone reservoirs, such as the LXF sandstone, which have experienced strong diagenetic modifications during their geological histories.

A π–π Stacked High-Performance Organic Anode for Durable Rocking-Chair Zinc-Ion Battery

Sustainable organic materials have gained considerable attention as electrodes for zinc-ion batteries (ZIB) due to their high theoretical capacity, structural versatility, and environmental friendliness. However, issues of inferior capacities and poor rate performance owing to limited inherent electronic conductivity and severe dissolution still persist. Herein, sandwich-structured perylene diimide-ethylene diamine/graphene (PDI-EDA/EG) composites are judiciously designed and synthesized. The two-dimensional graphene host can interact with the PDI-EDA polymer through π–π stacking, endowing accelerated ion/electron transfer, abundant active sites, excellent structural integrity, and mitigated solubility of the hybrid electrodes. When evaluated as an anode in ZIB, the hybrid electrode delivers a high capacity (110.2 mAh g−1 at 0.1 A g−1), superior rate capability (88.9 mAh g−1 at 5 A g−1), and exceptional durability (93.4% capacity retained after 1000 cycles). The structure evolution of the hybrid electrode during the insertion/extraction cycle was investigated by ex-situ Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy (XPS), revealing the reversible Zn2+ storage at carbonyl sites. In addition, a prototype rocking-chair ZIB cell was constructed with a zinc pre-intercalated MnO2 cathode, displaying an ultrahigh energy density of 54.9 Wh kg−1 at a power density of 42.5 W kg−1 and excellent stability with negligible capacity decay after 1000 cycles.

The role of the iodide/iodine couple as a redox mediator in the dissolution of chalcopyrite in sulfate media. An electrochemical study

A detailed study has been made of the effect of the addition of iodine/iodide on the electrochemistry of the dissolution of chalcopyrite in acidic sulfate media containing iron(III). Mixed potential measurements have revealed that the potential is higher with iodine as an oxidant compared to iron(III) although the solution potentials are similar. Potentiostatic measurements in the absence of the oxidants at the measured mixed potentials have shown that chalcopyrite should dissolve some five times faster with iodine as the oxidant. Linear sweep voltammetry has confirmed the much higher reversibility of the iodine/iodide couple on a chalcopyrite surface than that of the iron(III)/iron(II) couple. Limited dissolution tests have confirmed that chalcopyrite dissolves more rapidly with iodine as the oxidant at rates similar to those predicted from the electrochemical measurements. A preliminary spectrophotometric study of the kinetics of the oxidation of iodide by iron(III) in sulfate media has shown that the rate is significantly slower than previously assumed and that the reaction occurs in two stages with tri-iodide as the initial product that is slowly oxidised to iodine. At the low concentrations necessary for economic application, iodide ions do not effect the rate of oxidation of iron(II) by dissolved oxygen in chloride solutions. It is suggested that the use of iodide as a redox mediator during heap leaching of chalcopyrite ores by acidic ferric sulfate lixiviants is unlikely to change current problems with the slow rate of dissolution under ambient conditions.

Development of Carvedilol-Loaded Albumin-Based Nanoparticles with Factorial Design to Optimize In Vitro and In Vivo Performance.

Carvedilol, an anti-hypertensive medication commonly prescribed by healthcare providers, falls under the BCS class II category due to its low-solubility and high-permeability characteristics, resulting in limited dissolution and low absorption when taken orally. Herein, carvedilol was entrapped into bovine serum albumin (BSA)-based nanoparticles using the desolvation method to obtain a controlled release profile. Carvedilol-BSA nanoparticles were prepared and optimized using 32 factorial design. The nanoparticles were characterized for their particle size (Y1), entrapment efficiency (Y2), and time to release 50% of carvedilol (Y3). The optimized formulation was assessed for its in vitro and in vivo performance by solid-state, microscopical, and pharmacokinetic evaluations. The factorial design showed that an increment of BSA concentration demonstrated a significant positive effect on Y1 and Y2 responses with a negative effect on Y3 response. Meanwhile, the carvedilol percentage in BSA nanoparticles represented its obvious positive impact on both Y1 and Y3 responses, along with a negative impact on Y2 response. The optimized nanoformulation entailed BSA at a concentration of 0.5%, whereas the carvedilol percentage was 6%. The DSC thermograms indicated the amorphization of carvedilol inside the nanoparticles, which confirmed its entrapment into the BSA structure. The plasma concentrations of carvedilol released were observable from optimized nanoparticles up to 72 h subsequent to their injection into rats, revealing their longer in vivo circulation time compared to pure carvedilol suspension. This study offers new insight into the significance of BSA-based nanoparticles in sustaining the release of carvedilol and presents a potential value-added in the remediation of hypertension.

Incorporating valsartan in sesame oil enriched self-nanoemulsifying system-loaded liquisolid tablets to improve its bioavailability

Valsartan (VST) is a poorly soluble antihypertensive drug characterized by its limited dissolution rate and low bioavailability. This study aims to improve VST solubility and dissolution rate via developing liquisolid tablets (LSTs) containing a self-nanoemulsifying drug delivery system (SNEDDS), which is expected to enhance VST bioavailability. This aim was achieved via two designs of experiment. The first was the simplex-lattice design to optimize VST-loaded-SNEDDS using sesame oil, Tween 80, and polyethylene glycol 400. The second was the 32-3-level factorial design to optimize the liquisolid system using the SNEDDS-loaded VST and Neusilin®US2 as a carrier and fumed silica as a coating material. Different excipient ratios (X1) and varioussuper-disintegrants (X2) were also used in developing the optimized VST-LSTs. Thein vitrodissolution of VST from LSTs was compared with the marketed product (Diovan®). Non-compartmental analysis of plasma data after extravascular input with the linear trapezoidal method was used to calculate thepharmacokinetic parameters of the optimized VST-LSTs compared with the marketed tablet in male Wistar rats. The optimized SNEDDS compromised 24.9% sesame oil, 33.3% surfactant, and 41.8% cosurfactant, giving 173.9 nm size and 63.9 mg/ml loading capacity. Also, the SNEDDS-loaded VST tablet revealed good quality attributes with the release of 75% of its content in 5 min and 100% within 15 min. On the other hand, the marketed product took 1 h for the entire drug to be released.Moreover, the maximum plasma concentration (Cmax) of the optimizedVST-LSTwas6585.33 ng/ml within 1 h (Tmax), compared to 2884.67 ng/ml within 2 h of the marketed tablet.The relative bioavailability of the SNEDDS-loaded VST tablet was 213.7% compared to that of the marketed tablet, indicating that this formulation approach could be applied for increasing solubility, dissolution behavior in GIT, and bioavailability of poorly water-soluble drugs.