Spinning Nuclear Magnetic Resonance Spectroscopy Research Articles

A New Class of Oxyhalide Solid Electrolytes NaNbCl6‐2xOx for Solid‐state Sodium Batteries

AbstractSodium‐based batteries are gaining momentum due to the abundance and lower cost of sodium compared to lithium. Solid‐state sodium batteries can also provide further safety advantages. However, sodium‐based solid‐state electrolytes (SSEs) that meet all the rigorous requirements, such as high ionic conductivity, oxidative stability with the cathode, and ease of processability, are lacking. We present here a new class of sodium‐based oxyhalide electrolytes NaNbCl6‐2xOx with a facile mechanochemical synthesis. The oxyhalide NaNbCl4O exhibits close to two orders of magnitude higher ambient‐temperature sodium‐ion conductivity (1.03×10−4 S cm−1) compared to the halide counterpart NaNbCl6 (3×10−6 S cm−1). Structural motifs unique to the oxygen content in NaNbCl6‐2xOx are identified with 23Na and 93Nb magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy and x‐ray diffraction (XRD). Solid‐state sodium batteries assembled with NaNbCl4O electrolyte and the cobalt‐ and nickel‐free layered Na0.70Fe0.3Mn0.65Al0.05O2 cathode exhibit a maximum discharge capacity of 155 mAh g−1 with good cycle life at ambient temperature.

Densely packed glass structure caused by seven-coordinated Zr in high elastic modulus Al2O3–SiO2–ZrO2 glasses

Al2O3–SiO2–ZrO2 ternary glasses were fabricated using a levitation technique. The addition of ZrO2 to the Al2O3–SiO2 glasses strongly affected their thermal, mechanical, and structural properties. Several compositions were partially vitrified at the laser-melted area without levitation although their melting required temperatures higher than 2000°C. With increasing ZrO2 content, the elastic moduli linearly increased, and the 50Al2O3–20SiO2–30ZrO2 glass exhibited a Young′s modulus of 166 GPa and Vickers hardness HV of 11 GPa. Conversely, crack resistance significantly decreased with the addition of ZrO2. Density measurements, Zr L2,3-edge and K-edge X-ray absorption fine structure analyses, and 27Al and 29Si magic-angle spinning nuclear magnetic resonance spectroscopy were performed to investigate the local structure around Zr, Al, and Si in the glasses. Zr formed distorted ZrO7 as in monoclinic ZrO2, which has been rarely found in conventional oxide glasses. The highly oxygen-coordinated Al atoms such as AlO5 and AlO6, were the main components in the glasses rather than AlO4. The majority of Si atoms form SiO4 with four bridging oxygen (Q4). Among the four bridging oxygens, the number of oxygens connected to Al or Zr clearly increased with decreasing SiO2 content. The high packing density of the ternary glasses that resulted in high elastic moduli originated from the highly oxygen-coordinated Zr and Al and their close bonding with SiO4 without generating nonbridging oxygens.

ZnH2P4N8: Case Study on Topochemical Imidonitridophosphate High-Pressure Synthesis.

Nitridophosphates are subject of current research, as they have a broad spectrum of properties and potential applications, such as ion conductors or luminescent materials. Yet, the subclass of imidonitridophosphates has been studied less extensively. The primary reason is that the controlled N-H functionalization of nitridophosphates is not straight forward, making targeted synthesis more challenging. Inspired by the high-pressure (HP) post-synthetic modification of nitridophosphates, we present the topochemical HP deprotonation of phosphorus nitride imides using the high-pressure polymorph β-PN(NH) as an example. Additional incorporation of Zn2+ results in the first quaternary transition metal imidonitridophosphate ZnH2P4N8. The crystal structure was elucidated by single-crystal X-ray diffraction (SCXRD), energy-dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (PXRD) and solid-state magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR). In addition, the presence of H as part of an imide group was confirmed by IR spectroscopy. The potential of this defunctionalization approach for controlling the N-H content is demonstrated by the preparation of partially deprotonated intermediates ZnxH4-2xP4N8 (x≈0.5, 0.85). This topochemical high-pressure reaction represents a promising way to prepare, control and manipulate new imide-based materials without altering their overall anionic framework.

Catalytic benzylation of arenes using metal-ion modified HY zeolites for sustainable synthesis

Microporous zeolites are commonly employed as catalysts for the benzylation of arenes and benzyl alcohol. However, their catalytic efficiency is often compromised by diffusion limitations, particularly in reactions involving larger arenes. In this study, we developed metal-ion modified HY zeolites using Zn, Mg, and Ni as dopants and investigated their catalytic performance in the benzylation of a range of arenes, including toluene, benzene, mesitylene, p-xylene and with benzyl alcohol (BzOH). The structural and acidic properties of the modified HY zeolites were characterized using a combination of techniques including scanning electron microscopy (SEM), X-ray diffraction (XRD), N₂ adsorption–desorption isotherms, Fourier-transform infrared (FTIR) spectroscopy, ammonia temperature-programmed desorption (NH₃-TPD), and proton magic angle spinning nuclear magnetic resonance (1H MAS NMR) spectroscopy. The presence of catalytically active Brønsted acid sites (BAS) was detected by 1H MAS NMR spectroscopy and it was demonstrated that the HY zeolite's acidity is considerably modulated by the addition of metal ions. The catalytic evaluations indicated that the metal-ion modified HY zeolites exhibited superior activity compared to unmodified HY zeolite, with the catalytic performance following the order Zn/HY > Ni/HY > Mg/HY > HY for the benzylation of benzyl alcohol with mesitylene. Further investigation into the mechanism revealed that the synergistic effect of metal ions and acidity plays a crucial role in enhancing the accessibility of arenes to the surface catalytic sites and thereby improving catalytic performance. These findings underscore the importance of the metal-acidity synergy in optimizing the catalytic efficacy of modified HY zeolites for selective benzylation reactions.

Wide-pore fully porous mixed-mode octyl/pyridyl-bonded silica material with pH-dependent surface charge reversal for high-performance hydrophobic charge-induction chromatography of proteins

In an attempt to overcome silanophilic interactions like observed on popular reversed-phase butyl‑bonded silica stationary phases in protein HPLC, a mixed-mode stationary phase based on wide pore silica (3 µm, 300 Å) was prepared by co-immobilization of octyl and 2-pyridylethyl ligands. The surface modification was performed by a new approach using synthesized functional silatranes of the above ligands and prewetted silica. It allowed to generate a dense polymeric siloxane layer on the silica surface. Butyl-bonded silica and octyl/3-aminopropyl-bonded mixed-mode silica phases were prepared for comparison. The modified silicas were subsequently characterized by elemental analysis regarding ligand densities, by solid-state 29Si and 13C cross polarization/magic angle spinning nuclear magnetic resonance spectroscopy for confirming the surface-bonded structure, and by pH-dependent ζ-potential measurements via electrophoretic light scattering providing net surface charge information at distinct pH values. While the classical butyl‑bonded stationary phase revealed negative ζ-potential over the entire pH range investigated (pH 3.5–9.5) due to residual silanols and the mixed-mode octyl/3-aminopropyl-bonded silica positive ζ-potential over the entire pH range, pH-dependent charge reversal was observed at approximately pH 5.5 for the octyl/pyridyl-bonded stationary phase. Then, a test set of proteins differing in hydrophobicities and isoelectric points was employed to evaluate the retention characteristics of all three synthesized stationary phases over the pH range of 3 to 7.5 by acetonitrile-gradient elution reversed-phase HPLC. Under acidic conditions (pH 3) the mixed-mode phases octyl/pyridyl-silica and octyl/aminopropyl-silica showed reduced retention and improved peak shapes due to repulsive interactions preventing silanophilic interactions, while protein separations by their hydrophobicities were achieved (repulsive charge-assisted protein RPLC). Finally, the prepared novel mixed-mode octyl/pyridyl-bonded stationary phase was evaluated in hydrophobic charge induction chromatography mode for protein separation of the same test set. Instead of an organic modifier gradient, elution was enforced by a pH gradient from almost neutral to acidic pH at constant organic modifier content of 10 %. This chromatographic mode showed orthogonal retention characteristics and reversed elution order compared to above organic gradient RP-HPLC. In addition, significantly less organic solvent was used under these conditions, classifying it as a green protein LC technology.

Deep purification of perfluorinated electronic specialty gas with a scalable metal–organic framework featuring tailored positive potential traps

The sequestration of trace hexafluoropropylene (C3F6) is a critical yet formidable task in the production of high-purity perfluoropropane (C3F8), an important perfluorinated electronic specialty gas (F-gas) in the advanced electronics industry. Traditional adsorbents struggle with uneven, low-pressure uptake and compromises in selectivity. This work utilizes aperture size-electrostatic potential matching within a robust metal–organic framework (Al-PMA) to facilitate selective, reversible binding of C3F6 while excluding larger C3F8 molecules. The presence of bridging hydroxyl groups (μ2-OH) in Al-PMA creates positive electrostatic potential traps that securely anchor C3F6 through strong hydrogen bonding, evidenced by in-situ infrared and 19F magic angle spinning nuclear magnetic resonance spectroscopy. Breakthrough experiments demonstrate the efficient removal of trace C3F6 from C3F8 under ambient conditions, achieving C3F8 purity exceeding 99.999%. The scalability of Al-PMA synthesis, remarkable stability, and exceptional performance highlight its potential as a promising adsorbent for industrial C3F6/C3F8 separations.

Improving the Stability of 75Li2S·25P2S5 Glass-Ceramic Electrolytes Against Lithium Metals Through Li2O Doping

The chemical and electrochemical stability between solid-state electrolytes (SSEs) and lithium metals is one of the crucial factors in the performance of all-solid-state lithium batteries (ASSLBs). Doping modification has been shown to improve the ionic conductivity and air stability of SSEs, but further research is needed to demonstrate its effectiveness in enhancing stability with lithium metal. In this work, a series of Li2O-doped 75Li2S·25P2S5 glass-ceramic electrolytes have been successfully synthesized using ball milling method. Powder X-ray diffraction (pXRD) and 7Li magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy results revealed that Li2O doping effectively reduced the percentage of residual Li2S in the ball milling stage and generated a high ionic conductivity phase Li7P3S11 during annealing. The electrolyte has the highest ionic conductivity (1.5 × 10−4 S cm−1 at room temperature) when doped with 1 mol% Li2O. Various electrochemical characterizations have shown that all doped electrolytes can effectively slow/suppress lithium dendrite formation while being chemically and electrochemically stable to some extent. Among these, 1 mol% Li2O-doped electrolyte performs the best, as the Li|1Li2O|Li cell maintains voltage and resistance nearly unchanged after 1000 h and 900 cycles, with no noticeable degradation in the material structure.

A New Class of Oxyhalide Solid Electrolytes NaNbCl6-2xOx for Solid-state Sodium Batteries.

Sodium-based batteries are gaining momentum due to the abundance and lower cost of sodium compared to lithium. Solid-state sodium batteries can also provide further safety advantages. However, sodium-based solid-state electrolytes (SSEs) that meet all the rigorous requirements, such as high ionic conductivity, oxidative stability with the cathode, and ease of processability, are lacking. We present here a new class of sodium-based oxyhalide electrolytes NaNbCl6-2xOx with a facile mechanochemical synthesis. The oxyhalide NaNbCl4O exhibits close to two orders of magnitude higher ambient-temperature sodium-ion conductivity (1.03 x 10-4 S cm-1) compared to the halide counterpart NaNbCl6 (3 x 10-6 S cm-1). Structural motifs unique to the oxygen content in NaNbCl6-2xOx are identified with 23Na and 93Nb magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy and x-ray diffraction (XRD). Solid-state sodium batteries assembled with NaNbCl4O electrolyte and the cobalt- and nickel-free layered Na0.70Fe0.3Mn0.65Al0.05O2 cathode exhibit a maximum discharge capacity of 155 mA h g-1 with good cycle life at ambient temperature.

Integrating HRMAS-NMR Data and Machine Learning-Assisted Profiling of Metabolite Fluxes to Classify Low- and High-Grade Gliomas.

Diagnosing and classifying central nervous system tumors such as gliomas or glioblastomas pose a significant challenge due to their aggressive and infiltrative nature. However, recent advancements in metabolomics and magnetic resonance spectroscopy (MRS) offer promising avenues for differentiating tumor grades both in vivo and ex vivo. This study aimed to explore tissue-based metabolic signatures to classify/distinguish between low- and high-grade gliomas. Forty-six histologically confirmed, intact solid tumor samples from glioma patients were analyzed using high-resolution magic angle spinning nuclear magnetic resonance (HRMAS-NMR) spectroscopy. By integrating machine learning (ML) algorithms, spectral regions with the most discriminative potential were identified. Validation was performed through univariate and multivariate statistical analyses, along with HRMAS-NMR analyses of 46 paired plasma samples. Amongst the various ML models applied, the logistics regression identified 46 spectral regions capable of sub-classifying gliomas with accuracy 87% (F1-measure 0.87, Precision 0.82, Recall 0.93), whereas the extra-tree classifier identified three spectral regions with predictive accuracy of 91% (F1-measure 0.91, Precision 0.85, Recall 0.97). Wilcoxon test presented 51 spectral regions significantly differentiating low- and high-grade glioma groups (p < 0.05). Based on sensitivity and area under the curve values, 40 spectral regions corresponding to 18 metabolites were considered as potential biomarkers for tissue-based glioma classification and amongst these N-acetyl aspartate, glutamate, and glutamine emerged as the most important markers. These markers were validated in paired plasma samples, and their absolute concentrations were computed. Our results demonstrate that the metabolic markers identified through the HRMAS-NMR-ML analysis framework, and their associated metabolic networks, hold promise for targeted treatment planning and clinical interventions in the future.

Resolving intermediates during the growth of aluminum deuteroxide (Hydroxide) polymorphs in high chemical potential solutions

Aluminum hydroxide polymorphs are of widespread importance yet their kinetics of nucleation and growth remain beyond the reach of current models. Here we attempt to unveil the reaction processes underlying the polymorphs formation at high chemical potential. We examine their formation in-situ from supersaturated alkaline sodium aluminate solutions using deuteration and time-resolved neutron pair distribution function analyses, which indicate the formation of individual Al(OD)3 layers as an intermediate particle phase. These layers ultimately stack to form gibbsite- or bayerite-like layered heterostructures. Ex-situ characterization of the recovered precipitates using 27Al magic angle spinning nuclear magnetic resonance spectroscopy, Raman, X-ray diffraction, and scanning electron microscopy, suggests the presence of additional intermediate states, an amorphous compound bearing both tetrahededrally- and penta-coordinated Al3+. These observations reveal the complex pathways to form Al(OD)3 monolayers via either transient pentacoordinate species or amorphous-to-ordered transitions. The subsequent crystallization of admixed gibbsite/bayerite is followed by an Al(OD)3 monolayer attachment process.

Interaction between peptide and solid lignin suggest mechanisms of abiotic covalent bond formation

The mechanisms behind the formation of soil organic matter (SOM) and associated nitrogen immobilization remain partially elusive, while ongoing research continues to shed light on carbon and nitrogen sequestration in the environment. Studies show that quinone-like structures within alkali-soluble humic extracts of SOM can bond covalently with nitrogen-containing molecules derived from proteinaceous organic matter. However, direct molecular evidence for this chemical bonding with lignin in the solid form and non-solvent-extracted SOM is lacking. Using gel-state 1H-15N heteronuclear single quantum coherence (HSQC) high-resolution magic angle spinning (HRMAS) nuclear magnetic resonance (NMR) spectroscopy, we demonstrate that a 15N-labeled peptide (glycine-glycine-glycine-arginine, GGGR), can covalently bind to solid, untreated, brown rotted wood as well as 1,2-naphthoquinone, a quinone-model molecule typically found in degraded lignin. The new peaks in both reactions represent a change in the environment surrounding the N-functional groups. Interaction of the 15N-labeled peptide with the model quinone produced NMR cross peaks that are similar to those of the solid lignin. This suggests that the quinone-like structures are the most likely functional groups to form covalent bonds with peptides in the degraded lignin. Both Michael addition and Schiff base formation is proposed when the peptide GGGR interacts with white oak lignin and 1,2-naphthoquinone. These processes are of considerable importance to N incorporation into SOM and offer insights into how proteinaceous molecules could potentially be preserved and sequestered through covalent bond formation.

High-Resolution Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy of Paired Clinical Liver Tissue Samples from Hepatocellular Cancer and Surrounding Region.

The global burden of liver cancer is increasing. Timely diagnosis is important for optimising the limited available treatment options. Understanding the metabolic consequences of hepatocellular carcinoma (HCC) may lead to more effective treatment options. We aimed to document metabolite differences between HCC and matched surrounding tissues of varying aetiology, obtained at the time of liver resection, and to interpret metabolite changes with clinical findings. High-resolution magic angle spinning nuclear magnetic resonance (HRMAS-NMR) spectroscopy analyses of N = 10 paired HCC and surrounding non-tumour liver tissue samples were undertaken. There were marked HRMAS-NMR differences in lipid levels in HCC tissue compared to matched surrounding tissue and more subtle changes in low-molecular-weight metabolites, particularly when adjusting for patient-specific variability. Differences in lipid-CH3, lipid-CH2, formate, and acetate levels were of particular interest. The obvious differences in lipid content highlight the intricate interplay between metabolic adaptations and cancer cell survival in the complex microenvironment of liver cancer. Differences in formate and acetate might relate to bacterial metabolites. Therefore, documentation of metabolites in HCC tissue according to histology findings in patients is of interest for personalised medicine approaches and for tailoring targeted treatment strategies.

Active species in chloroaluminate ionic liquids catalyzing low-temperature polyolefin deconstruction

Chloroaluminate ionic liquids selectively transform (waste) polyolefins into gasoline-range alkanes through tandem cracking-alkylation at temperatures below 100 °C. Further improvement of this process necessitates a deep understanding of the nature of the catalytically active species and the correlated performance in the catalyzing critical reactions for the tandem polyolefin deconstruction with isoalkanes at low temperatures. Here, we address this requirement by determining the nuclearity of the chloroaluminate ions and their interactions with reaction intermediates, combining in situ 27Al magic-angle spinning nuclear magnetic resonance spectroscopy, in situ Raman spectroscopy, Al K-edge X-ray absorption near edge structure spectroscopy, and catalytic activity measurement. Cracking and alkylation are facilitated by carbenium ions initiated by AlCl3-tert-butyl chloride (TBC) adducts, which are formed by the dissociation of Al2Cl7− in the presence of TBC. The carbenium ions activate the alkane polymer strands and advance the alkylation cycle through multiple hydride transfer reactions. In situ 1H NMR and operando infrared spectroscopy demonstrate that the cracking and alkylation processes occur synchronously; alkenes formed during cracking are rapidly incorporated into the carbenium ion-mediated alkylation cycle. The conclusions are further supported by ab initio molecular dynamics simulations coupled with an enhanced sampling method, and model experiments using n-hexadecane as a feed.

High-resolution magic angle spinning nuclear magnetic resonance of donor pancreatic tissue may predict islet viability prior to isolation.

For patients with type 1 diabetes mellitus complicated by severe hypoglycemia, clinical islet transplantation is an efficacious alternative to whole pancreas transplantation. While islet transplantation has improved over the last few years, there remain questions regarding its cost-effectiveness and donor allosensitization, which is exacerbated when islets from more than one donor are required. Understanding the features of a pancreas that would provide viable islets prior to isolation may lead to development of an accurate assay that could identify suitable pancreases and provide significant cost savings to a clinical islet transplantation program. In this pilot study, solid-state high-resolution magic angle spinning (HRMAS) nuclear magnetic resonance (NMR) spectroscopy was used to assess samples of convenience of human pancreatic tissue taken prior to islet isolation both before and after incubation using the two-layer perfluorocarbon (PFC)/University of Wisconsin (UW) solution cold-storage method. We observed that, prior to incubation, human pancreatic tissue exhibited evidence of hypoxia with decreased peak integrals associated with glucose and increased peak integrals corresponding to lactate and free fatty acids. After incubation, we observed a reversal of the hypoxia-induced damage, as integrals corresponding to glucose increased, and those corresponding to lactate and free fatty acid resonances decreased. Interestingly, a significant correlation between the ratio of the glucose integral (at 3.0-4.5 ppm) to the sum of the fatty acid (at 0.9 ppm) and lactate + fatty acid (at 1.3 ppm) integrals and glucose responsiveness, a measure of islet viability, of the isolated islets, was observed after incubation in PFC/UW solution for pancreases that responded to PFC/UW solution incubation (p = 0.02). Notably, pancreases with little or no change in the integral ratio after PFC/UW solution incubation had poor recovery. These results suggest that tissue recovery is a key feature for determining islet cell viability, and further that HRMAS NMR may be a practical method to quickly assess human donor pancreatic tissue prior to islet isolation for clinical transplantation.

Structural insight into palladium-nickel clusters over mordenite zeolite for carbene-insertion reaction

The advancement of heterogeneous catalysts incorporating metal clusters in the nanometric size range has garnered significant attention due to their extraordinary catalytic activity and selectivity. The detailed characterization and understanding of the atomic structure of these metal clusters within catalysts is crucial for elucidating the underlying reaction mechanisms. In the present study, a distinctive three-atom PdNi cluster, characterized by two Pd atoms at terminal positions and a central Ni atom, was synthesized over mordenite zeolite. The presence of atomic PdNi clusters within the eight-membered ring side pocket area was confirmed by multiple advanced analytical techniques, including magic-angle spinning nuclear magnetic resonance spectroscopy, synchrotron X-ray powder diffraction, extended X-ray absorption fine structure spectroscopy, and high-angle annular dark-field scanning transmission electron microscopy. The catalytic activity of the confined active species was examined by the carbene-mediated reactions of ethyl-2-diazoacetate to ethyl-2-methoxyacetate as a model reaction. Compared to the Pd-mordenite and Ni-mordenite, the PdNi-mordenite catalyst incorporates a PdNi cluster, which demonstrates a superior performance, achieving 100% conversion and high selectivity under the same reaction conditions. Our study elucidates the potential of constructing bimetallic clusters in zeolites, providing valuable insights for developing new heterogeneous catalysts applicable to a wide range of catalytic processes.

Monitoring the Geopolymerization Reaction of Geopolymer Foams Using 29Si and 27Al MAS NMR

This study aims to investigate the geopolymerization reaction of geopolymer foams produced with three different foaming agents: aluminum powder, zinc powder, and hydrogen peroxide. The geopolymerization reaction of geopolymer foam was monitored using the 27Al and 29Si magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy technique. 27Al MAS-NMR was used to monitor the reaction at an early stage, while 29Si and 27Al MAS-NMR analyses were employed at specific time intervals of 3, 6, 10, 15, and 28 days to examine the changes that occurred in the formed gel over time. We discussed in detail how the type of foaming agent used and the duration of the reaction both influence the quantity of gel formed and the amount of remnant fly ash. Our findings indicate that the type of foaming agent used affects the formation and structure of the gel, with aluminum powder leading to the highest gel formation. Additionally, the duration of the reaction plays a significant role in determining the quantity of remnant fly ash, with longer reaction times resulting in decreased fly ash content. This study sheds light on the relevance of understanding the role of foaming agents in the geopolymerization reactions of geopolymer foams and the influence of reaction time on the formed gel properties.

Structure and Properties of Na2S-SiS2-P2S5-NaPO3 Glassy Solid Electrolytes.

In the development of sodium all-solid-state batteries (ASSBs), research efforts have focused on synthesizing highly conducting and electrochemically stable solid-state electrolytes. Glassy solid electrolytes (GSEs) have been considered very promising due to their tunable chemistry and resistance to dendrite growth. For these reasons, we focus here on the atomic-level structures and properties of GSEs in the compositional series (0.6-0.08y)Na2S + (0.4 + 0.08y)[(1 - y)[(1 - x)SiS2 + xPS5/2] + yNaPO3] (NaPSiSO). The mechanical moduli, glass transition temperatures, and temperature-dependent conductivity were determined and related to their short-range order structures that were determined using Raman, Fourier transform infrared, and 31P and 29Si magic angle spinning nuclear magnetic resonance spectroscopies. In addition, the conductivity activation energies were modeled using the Christensen-Martin-Anderson-Stuart model. These GSEs appear to be highly crystallization-resistant in the supercooled liquid region where no measurable crystallization below 450 °C could be observed in differential scanning calorimetry studies. Additionally, these GSEs were found to be highly conducting, with conductivities on the order of 10-5 (Ω cm)-1 at room temperature, and processable in the supercooled state without crystallization. For all these reasons, these NaPSiSO GSEs are considered to be highly competitive and easily processable candidate GSEs for enabling sodium ASSBs.

Influences of alumina type and sulfate content on hydration and physicochemical changes in Portland–limestone cement

This study explored the influence of alumina type and gypsum content on the hydration, mechanical properties, and chemical changes of Portland–limestone cement (PLC) using isothermal calorimetry, inductively coupled plasma-optical emission spectroscopy (ICP-OES), ionic chromatography (IC), compressive strength testing, X-ray diffraction (XRD), 27Al magic angle spinning nuclear magnetic resonance (27Al MAS NMR) spectroscopy, and mercury intrusion porosimetry (MIP) testing. The addition of alumina shortened the induction period, accelerated the acceleration period, and increased the mechanical strength of the PLC pastes with 3 and 7 wt% gypsum. The acceleration effect and strength enhancement were not distinct in the PLC pastes with less gypsum (0.1 wt%). The addition of γ-alumina led to the greatest accelerating effect and strength improvement in the PLC pastes with 3 and 7 wt% gypsum, and the compressive strength achieved was comparable to those of pure Ordinary Portland cement (OPC) pastes without limestone. The addition of γ-alumina induced the rapid dissolution of gypsum and consumption of sulfate ions. The chemical change affected by the addition of alumina varied greatly depending on the gypsum content, and trends in AFt and AFm formation in the PLC pastes with different gypsum contents were confirmed. Finally, pore size refinement was observed through the addition of alumina to PLC pastes with 3 and 7 wt% gypsum.

Novel insights into the amorphous feature of granulated blast furnace slag-supplemented magnesium potassium phosphate cement and its effect on bulk properties

This paper reports the effects of MgO:PO4 (3, 9, and 15) ratio and granulated blast furnace slag dosage (0 wt%, 40 wt%, and 80 wt%) on the phase formation, microstructure, and bulk properties of magnesium potassium phosphate cement (MKPC). Results show that the supplementary of slag and the increment in MgO:PO4 inhibit the formation of K-struvite via X-ray diffraction. While the detections of 29Si magic-angle spinning nuclear magnetic resonance spectroscopy and scanning electron microscope-energy dispersion spectrum further unveil the dissolution of slag and the formation of Q4 amorphous structure in slag supplemented MKPCs. Although the Q4 structure increases the interplanar spacing of K-struvite even leads to its amorphization in MKPCs with high MgO:PO4 (>9), the optimum coexisting of K-struvite and Q4 structure minimizes the porosity and maximizes the compressive strength of MKPCs with MgO:PO4=3 and 40 wt% slag. These results are crucial to developing optimal mixture formulations of MKPC with superior mechanical performance and lower costs associated with their production.

An Integrated Metabolomics-Based Model, and Identification of Potential Biomarkers, of Perfluorooctane Sulfonic Acid Toxicity in Zebrafish Embryos.

Known for their high stability and surfactant properties, per- and polyfluoroalkyl substances (PFAS) have been widely used in a range of manufactured products. Despite being largely phased out due to concerns regarding their persistence, bioaccumulation, and toxicity, legacy PFAS such as perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid continue to persist at high levels in the environment, posing risks to aquatic organisms. We used high-resolution magic angle spinning nuclear magnetic resonance spectroscopy in intact zebrafish (Danio rerio) embryos to investigate the metabolic pathways altered by PFOS both before and after hatching (i.e., 24 and 72 h post fertilization [hpf], respectively). Assessment of embryotoxicity found embryo lethality in the parts-per-million range with no significant difference in mortality between the 24- and 72-hpf exposure groups. Metabolic profiling revealed mostly consistent changes between the two exposure groups, with altered metabolites generally associated with oxidative stress, lipid metabolism, energy production, and mitochondrial function, as well as specific targeting of the liver and central nervous system as key systems. These metabolic changes were further supported by analyses of tissue-specific production of reactive oxygen species, as well as nontargeted mass spectrometric lipid profiling. Our findings suggest that PFOS-induced metabolic changes in zebrafish embryos may be mediated through previously described interactions with regulatory and transcription factors leading to disruption of mitochondrial function and energy metabolism. The present study proposes a systems-level model of PFOS toxicity in early life stages of zebrafish, and also identifies potential biomarkers of effect and exposure for improved environmental biomonitoring. Environ Toxicol Chem 2024;43:896-914. © 2024 SETAC.