Cluster Ions Research Articles

The Synergistic Effect of High Intensity Focused Ultrasound on In-vitro Remineralization of Tooth Enamel by Calcium Phosphate Ion Clusters.

Remineralization of dental enamel is an important intervention strategy for the treatment of demineralized lesions. Existing approaches have limitations such as failure to adequately reproduce both the ideal structural and mechanical properties of the native tooth. The ability of ultrasound to control and accelerate the crystallization processes has been widely reported. Therefore, a new approach was explored for in-vitro enamel remineralization involving the synergistic effect of high-intensity focused ultrasound (HIFU) coupled with calcium phosphate ion clusters (CPICs). The demineralized enamel was treated with CPICs, with or without subsequent HIFU exposure for different periods (2.5, 5, and 10 min). The specimens were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and Raman spectroscopy. The surface hardness and crystallographic properties of the treated specimens were evaluated using Vickers microhardness testing and X-ray diffraction (XRD), respectively. SEM revealed distinct, organized, and well-defined prismatic structures, showing clear evidence of remineralization in the combined CPIC/HIFU treatment groups. AFM further revealed a decrease in the surface roughness values with increasing HIFU exposure time up to 5 min, reflecting the obliteration of interprismatic spaces created during demineralization. The characteristic Raman band at 960 cm-1 associated with the inorganic phase of enamel dominated well in the HIFU-treated specimens. Importantly, microhardness testing further demonstrated that new mineral growth also recovered the mechanical properties of the enamel in the HIFU-exposed groups. Critical to our aspirations for developing this into a clinical process, these results were achieved in only 5 min. HIFU exposure can synergise and significantly accelerate in-vitro enamel remineralization process via calcium phosphate ion clusters. Therefore, this synergistic approach has the potential for use in future clinical interventions.

Nucleation Domains in Biomineralization: Biomolecular Sequence and Conformational Features.

Biomolecules play a vital role in the regulation of biomineralization. However, the characteristics of practical nucleation domains are still sketchy. Herein, the effects of the representative biomolecular sequence and conformations on calcium phosphate (Ca-P) nucleation and mineralization are investigated. The results of computer simulations and experiments prove that the line in the arrangement of dual acidic/essential amino acids with a single interval (Bc (Basic) -N (Neutral) -Bc-N-Ac (Acidic)- NN-Ac-N) is most conducive to the nucleation. 2α-helix conformation can best induce Ca-P ion cluster formation and nucleation. "Ac- × × × -Bc" sequences with α-helix are found to be the features of efficient nucleation domains, in which process, molecular recognition plays a non-negligible role. It further indicates that the sequence determines the potential of nucleation/mineralization of biomolecules, and conformation determines the ability of that during functional execution. The findings will guide the synthesis of biomimetic mineralized materials with improved performance for bone repair.

Enabling high-temperature application of Nafion membrane via imitating ionic clusters in proton conduction channels

Nafion membranes, representative of perfluorosulfonic acid (PFSA) proton exchange membranes are not effective in dehydrated state and high-temperature condition (>100 oC). The traditional hybrid modification would lower the mechanical strength of the membrane due to the large-scale phase separation. In this work, a hyperbranched polyamide (HBM) featuring high sulfonate concentration and nanoparticle morphology is synthesized and non-destructively filled into Nafion matrix to imitate the “ionic cluster” to accelerate the proton conduction at elevated temperature. During the non-destructively membrane modification, the Nafion PFSA membrane is swelled in the solution and the main chain structure is expanded, the HBM macromolecules is simultaneously filled into the membrane together with the solvent. After the removal of solvent, HBM end-capped with –COOH forms strong hydrogen bonds with the sulfonate groups in Nafion matrix. As a result, proton conductivity of the composite membrane can reach 0.047 S/cm, which is 1.9 times higher than that of the pristine Nafion membrane, at 110 oC and 60% RH. Given the excellent overall stability, fuel cell performance of the HBM-modified Nafion membrane is studied and a 30% increase in power density is observed, suggesting a viable strategy to expand the operation temperature of PFSA-based fuel cells.

Influence of Monomer Configuration on the Performance of Poly(quaterphenyl piperidinium) Anion Exchange Membranes

Polymeric anion exchange membranes (AEM)s are crucial components in many electrochemical energy devices where the performance is strongly influenced by the ionic conductivity, mechanical robustness, and thermochemical stability of the materials.1,2 AEMs are susceptible to degradation due to the chemically aggressive nature of the hydroxide ion, which significantly restricts their long-term applicability, especially at elevated temperature.3,4 Improving the polymer backbone design by, e.g., eliminating ether linkages from the polymer backbone is an approach to improve alkaline stability.5 Moreover, by introducing multi-ring aromatic segments, the rigidity, hydrophobicity, and “blockiness” of the polymer backbone increase, leading to mechanical robustness and enhanced microphase separation (ionic clustering) of the AEM.6 Obviously, the configuration of the multi-ring aromatic segments will have an influence, which can be used to tune and improve the properties of the polymers and AEMs.7,8 In the present project, we investigated the influence of the configuration of quaterphenyl monomers in poly(quaterphenyl piperidinium)s on the corresponding AEM properties. Three different monomers (isomers) with different connectivity between the four rings were investigated: para-para, para-meta, and meta-meta. The polymers were prepared by superacid-mediated Friedel-Crafts type polycondensations (polyhydroxyalkylations) involving N-methyl piperidone and the respective quaterphenyl. Subsequently, the polymers were fully quaternized with methyl iodide to prepare a series of ether-free poly(quaterphenyl piperidinium)s with different backbone configurations and chain flexibility. In this presentation, the influence of the quaterphenyl configuration on AEM properties such as water uptake, hydroxide conductivity, ionic clustering, thermal and chemical stability will be discussed. Li, C.; Baek, J. B., Nano Energy 2021, 87, 106162.Aili, D.; Rykær Kraglund, M.; Rajappan S.C.; Serhiichuk, D.; Xia Y.; Deimede V.; Kallitsis, J.; Bae, C.; Jannasch, P.; Henkensmeier, D.; Jensen, J.O., ACS Energy Lett. 2023, 8, 1900–1910.Mohanty, A. D.; Bae, C., Mater. Chem. A 2014, 2(41), 17314-17320.Jeon, J. Y.: Park, S.; Han, J.; Maurya, S.; Mohanty, A. D.; Tian, D.; Saikia, N.; Hickner, M. A.; Ryu, C. Y.; Tuckerman, M. E.; Paddison, S. J.; Kim, Y. S.; Bae, C., Macromolecules 2019, 52(5), 2139–2147.Olsson, J. S.; Pham, T. H.; Jannasch, P., Funct. Mater. 2018, 28(2), 1702758.Liu, M.; Hu, X.; Hu, B.; Liu, L.; Li, N., Membr. Sci. 2022, 642, 119966.Pham, T. H.; Olsson, J. S.; Jannasch, P., Mater. Chem. A 2019, 7(26), 15895-15906.Lee, W-H;Park, E. J.; Junyoung, H.; Shin, D. W.; Kim, Y. S.; Bae, C., ACS Macro Lett. 2017, 6(5), 566–570.

Hydroxide Conducting Naphthalene-Containing Polymers and Membranes Via Polyhydroxyalkylations

Anion exchange membranes (AEMs) are critical components of alkaline membrane water electrolyzers and fuel cells that are under development today [1,2]. Consequently, there is a strong demand for highly conductive and alkali-stable AEMs. In this context, polyhydroxyalkylation has emerged as one of the most efficient synthetic pathways to chemically resistant polymer backbones for AEMs. In these Friedel-Crafts type polycondensations, an electron-rich aromatic compound reacts with an activated ketone or aldehyde to produce an aryl-ether-free polymer. The desired quaternary ammonium cations are then usually introduced through a Menshutkin reaction [3,4].In the current work, we have employed naphthalene-based compounds as monomers in polyhydroxyalkylations to prepare a series of high-molecular weight poly(naphthalene alkylene)s with various naphthalene contents. These polymers were then quaternized and cast into AEMs. Here, we will discuss the influence of the naphthalene monomer type and content on AEM properties such as solubility, water uptake, ion conductivity, ionic clustering, thermal and alkaline stability, and also the prospects of using these AEMs in electrochemical systems.

(Invited) Advances in XPS Analysis of Battery Materials

Energy storage (batteries, capacitors) and conversion (solar cells) systems are increasing demand for vehicles, mobile electronics, and other areas as alternatives to fossil fuels.These systems are complex and multi-component with many materials and interfaces that are difficult to handle and characterize. To optimize materials properties and improve battery lifetimes, there is a pressing need for physicochemical characterization approaches with air-free handling capabilities, high spatial resolution, the ability to analyze buried interfaces without damaging the chemistry, and the need to bridge the gap by in situ and operando surface analysis.Developments in X-ray Photoelectron Spectrometers (XPS) open up new capabilities to address these challenges. In this talk, I will discuss how we can overcome obstacles in analyzing battery materials using: Inert environment transfer vessel: This allows for handling battery materials in an air-free environment, which is essential for preventing oxidation and other degradation reactions.Microprobe X-ray source with <5 µm spatial resolution: This provides high spatial resolution for analyzing small areas of interest, such as SEI, dendrites and other features.Hard X-ray source and cluster ion gun source: These allow for the analysis of buried interfaces not accessible by conventional soft X-ray XPS.In situ energy gap measurements: These allow for the study of the changes in the electronic structure of battery materials as they are cycled, which can provide insights into the mechanisms of charge storage and discharge.Operando XPS experiments: These allow for the study of the changes in the surface structure of battery materials as they are operating, which can provide insights into the factors that affect their performance. Figure 1

Sulfide-Based Solid-State Lithium-Sulfur Batteries: An in-Depth Study of the Li-Electrolyte Interface

The development of solid-state batteries has gained significant attention in recent years, owing to their potential to enhance the temperature range and energy density of energy storage devices. Sulfide-based electrolytes are some of the most promising candidates for solid-state batteries, thanks to their high ionic conductivity and low processing temperature. For lithium-sulfur (Li-S) batteries, the transition from liquid to solid electrolytes holds even greater promise. Sulfur is a readily available cathode material known for its high specific capacity, which endows Li-S batteries with remarkable specific energy and favourable environmental and economic impact. In liquid electrolytes however, the solubility of sulfur and lithium polysulfide causes a multitude of issues that hamper the performance of the Li-S system: rapid self-discharge, redox shuttle mechanism during charging, and loss of active sulfur and lithium material due to direct chemical reactivity. Solid-state Li-S cells are not prone to these issues, but they have, of course, issues of their own. Amongst them, the stability of the interface between the electrolyte and the lithium is of crucial importance to allow the use of this very high energy density negative electrode.In the present study, we compare two sulfide electrolytes, Li6PS5Cl and Li7P3S11, and assess their respective stability against lithium. We used innovative methods to characterize the interphase between the sulfide and the lithium without damaging it upon dismantling the cell. The nature and the properties of this interphase was characterised via EIS, XPS and ToF-SIMS.The EIS study showed that Li6PS5Cl forms a much more stable interphase with lithium than Li7P3S11, which is in accordance with most recent results in the literature. The XPS study confirmed the chemical composition of the interphase. Li2S and Li3P were present for both electrolytes. In the case of Li6PS5Cl, LiCl was also identified as expected. Gas cluster ion beam (GCIB) assisted abrasion of the interphase followed by in-situ XPS and ToF-SIMS suggested a separation of the components of the interphase depending on the depth of the abrasion. The interphase was found to be organised as Li2S-, Li3P- or LiCl-rich discrete layers, with the Li2S-rich layer being consistently the closest to lithium. This result confirms and completes the most recent research in the field published by Otto et al. in 2022 (doi: 10.1002/admi.202102387).To establish solid-state batteries as a practical energy storage option, it is essential to fully understand and effectively manage the Li-electrolyte interface. These findings suggest that thanks to the relative stability of its interface with lithium, Li6PS5Cl is the better option for solid-state lithium metal cells. It also sheds light on the reasons why this interface is more stable. The self-assembled lamellar structure of the interphase could also inspire strategies to better control the stability of solid electrolytes versus lithium.

Evolution of nanohillocks by fullerene ion-induced localized plasma

Surface nanostructures etch without chemicals; owing to this, their development is a crucial technical process. Surface nanohillocks may be created by irradiating yttrium iron garnet (YIG) with 30-MeV C60 cluster ions. The nanohillock creation mechanism is disputed. In this study, we propose that the formation mechanism is a plasma collective effect of charged particles that depends on localized rogue waves. Rogue waves will explain YIG surface nanohillock creation using a traditional hydrodynamic plasma model. Analytically solving hydrodynamic ion fluid equations and Maxwellian electron distributions yields a non-linear Schrödinger equation. Solving the latter gives us plausible rogue wave domains. Rogue waves concentrate charged ions from the surroundings into a small, confined zone, generating surface nanohillocks. The relevance of different plasma parameters is highlighted in the rogue wave profile.

Thermo-Mechanical Stability of Hydrocarbon-Based Pemion® Proton Exchange Membranes

Considering the environmental concerns about the disposal of perfluorosulfonic acid (PFSA) membranes as well as the growing interest in higher temperature operability of polymer electrolyte membrane fuel cells (PEMFCs), non-fluorinated hydrocarbon-based proton exchange membranes (PEMs) with aromatic backbones have become an increasingly active area of research. Low reactant cross-over, tunable electrochemical properties, and differentiated chemistries and potentially safer and cost-reducing synthesis procedures, are additional favourable features of hydrocarbon-based PEMs for prospective use in PEMFCs [1]. Vulnerable linking units, however, are known to be the main disadvantages of these polymers in the oxidative environment of fuel cells. During PEMFC operation, destructive radical species such as hydroxyl (HO•) are produced, causing polymer degradation and thinning in the membrane [2]. Recently, sulfo-phenylated polyphenylenes (sPPPs) have shown outstanding oxidative stability due to a polymer backbone comprising only aryl-aryl bonds, with mitigated chemical degradation in ex-situ and in-situ durability studies [3, 4]. Another concern is regarding the thermo-mechanical stability of PEMs. Thus, a systematic thermo-mechanical stability study is required to confirm the potential of sPPP-based PEMs to replace conventional PFSAs, especially for high temperature PEMFC, i.e., 110-120 °C.The present research objective is to assess the thermo-mechanical stability of a commercial reinforced hydrocarbon-based PEM, Pemion® (PF1-HLF8-15-X, 15 µm thick, reinforced), as well as a mechanically-reinforced PFSA-based reference membrane, across a wide range of temperature (30-120 °C) and relative humidity (RH) (10-90%) conditions that includes the crucial high temperature window of interest for future PEMFCs [6]. To this end, a comprehensive design of experiment yielded 19 tensile tests at various hygrothermal conditions with dynamic mechanical analyzer (DMA 850; TA Instruments) equipped with an external environmental chamber accessory (TA Instruments, RH Accessory). Important mechanical properties such as Young’s modulus, ultimate tensile stress, yield stress, maximum elongation at break, strain hardening, and modulus of resilience were extracted and discussed as well. Datapoints were fitted for empirical model development and mechanical properties were estimated for high temperature and RH conditions beyond the capability of the instrument. This method can be employed to assess if the mechanical properties of membrane materials can be retained at higher temperatures, regardless of polymer chemistry and type. Storage modulus and loss modulus were separately measured in a dynamic mode to observe the impact of temperature on the mechanical response of the hydrophobic backbone and hydrophilic ionic clusters, respectively.Overall, Pemion® demonstrates tough tensile properties in the stress-strain tests due to its sterically encumbered polyphenylene backbone (Figure 1a), whereas the reference PFSA (Figure 1b) shows elastomer-like behavior with much lower Young’s modulus, yield stress, and strain hardening (slope of the curve in the plastic deformation region). Figure 1c-f show the main viscoelastic properties extracted from the tensile tests at room (30 °C, 50% RH) and high temperature fuel cell conditions (110 °C, 50% RH). The modulus of elasticity and strain hardening of Pemion® membrane are almost temperature-independent, whereas these properties for the reinforced PFSA material undergo a significant decay at high-temperature ambience. Pemion® maintains good yielding strength even at high temperature and RH conditions (110-120 °C and 80% RH). Nevertheless, small mechanical stress values as low as 1 MPa can cause spontaneous yielding in the PFSA reference material above 110 °C. The modulus of resilience for the reinforced PFSA is also predicted to be zero at elevated hygrothermal conditions (i.e., 90 °C and 70% RH). This is interpreted as an approach to the material’s glass transition condition, where it loses its mechanical integrity and therefore, is potentially unsuitable for higher temperature PEMFC operation. Moreover, the dynamic mechanical thermal analysis revealed that Pemion® retains its robustness at hygrothermal ambience close to high-temperature PEMFCs, i.e., 110-120 °C and 40-50% RH, whereas the backbone of the PFSA material gradually loses its strength. Acknowledgements This project was financially supported by Natural Sciences and Engineering Research Council of Canada (NSERC), Ionomr Innovations Inc, Canada Foundation for Innovation (CFI), British Columbia Knowledge Development Fund (BCKDF), Western Economic Diversification Canada (WD), and Canada Research Chairs (CRC).

Eutectic Mixtures As Highly Concentrated and Molten Electrolytes with Nearly Single-Ion Conducting Behavior

Today's state-of-the-art liquid electrolytes in lithium ion batteries (LIBs) have a high ionic conductivity and good performance regarding their cycle life. (1) However, they pose a safety risk due to their high vapor pressures and low thermal stability. (1) Furthermore, due to the limited electrochemical stability of the solvent, liquid electrolytes are not suitable for the application in high-voltage LIBs. (2) Molten salts, also called ionic liquids (IL), or highly concentrated electrolytes (HCE) have high lithium ion concentrations, where nearly every solvent molecule is coordinated. Due to this, there are strong ion interactions and the formation of ion clusters that lead to an increased lithium ion transference number of >0.5. (3) Therefore, they can represent an alternative in the field of liquid electrolytes. Additionally, HCE exhibit a higher thermal and electrochemical stability compared to dilute electrolytes and can improve the cycle performance in lithium metal batteries. (4, 5)McOwen et al. reported the coordination of lithium ions and crystalline structures in HCE of the binary mixtures of ethylene carbonate (EC) and lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) with molar ratio up to 1:1. (6) Based on the concept of melting point depression as known from thermodynamics, room-temperature molten, highly concentrated electrolytes of a carbonate-based solvent with lithium sulfonyl imides were investigated. Instead of EC, the solvent pinacol carbonate (PIC) without acidic α-hydrogen atoms, but four bulky methyl groups was synthesized and used for eutectic mixtures, as the melting point of PIC is with 187 °C far above room-temperature. The physicochemical properties of these electrolytes are studied with respect to the different influence of lithium bis(fluorosulfonyl)imide and LiTFSI despite their same basic molecule structure. The focus will be on the electrochemical analysis by the means of the ionic conductivity, transference number and the electrochemical stability.In comparison to dilute liquid electrolytes the molten electrolytes show extremely high transference numbers, especially for the PIC-LiTFSI mixtures nearly a single-ion conducting behavior (0.9) is observed. This behavior can be explained by the formation of a 2D polymeric network within the HCE electrolyte as determined by crystallographic measurements in the solid state. Combined with the high electrochemical stability, a stable long-term cycling and dendrite suppression in symmetric lithium cells could be shown. Cycling in full cells with high-voltage cathode materials such as LiNi0.6Mn0.2Co0.2O2 (NMC622) or LiMn4O2 (LMO) against lithium metal anodes is applicable. References K. Xu, Chemical Reviews, 104(10), 4303–4417 (2004).J. Li, C. Ma, M. Chi, C. Liang and N. J. Dudney, Advanced Energy Materials, 5(4) (2015).K. M. Diederichsen, E. J. McShane and B. D. McCloskey, ACS ENERGY LETTERS, 2(11), 2563–2575 (2017).G. Jiang, F. Li, H. Wang, M. Wu, S. Qi, X. Liu, S. Yang and J. Ma, Small Struct., 2(5), 2000122 (2021).V. Nilsson, A. Kotronia, M. Lacey, K. Edstrom and P. Johansson, ACS Applied Energy Materials, 3(1), 200–207 (2020).D. W. McOwen, D. M. Seo, O. Borodin, J. Vatamanu, P. D. Boyle and W. A. Henderson, Energy & Environmental science, 7(1), 416–426 (2014).

Variation of Surface Propensity of Halides with Droplet Size and Temperature: The Planar Interface Limit.

The radial number density profiles of halide and alkali ions in aqueous clusters with equimolar radius ≲1.4 nm, which correspond to ≲255 H2O molecules, have been extensively studied by computations. However, the surface abundance of Cl-, Br-, and I- relative to the bulk interior in these smaller clusters may not be representative of the larger systems. Indeed, here we show that the larger the cluster is, the lower the relative surface abundance of chaotropic halides is. In droplets with an equimolar radius of ≈2.45 nm, which corresponds to ≈2000 H2O molecules, the polarizable halides show a clear number density maximum in the droplet's bulk-like interior. A similar pattern is observed in simulations of the aqueous planar interface with halide salts at room temperature. At elevated temperature the surface propensity of Cl- decreases gradually, while that of I- is partially preserved. The change in the chaotropic halide location at higher temperatures than the room temperature may considerably affect photochemical reactivity in atmospheric aerosols, vapor-liquid nucleation and growth mechanisms, and salt crystallization via solvent evaporation. We argue that the commonly used approach of nullifying parameters in a force field in order to find the factors that determine the ion location does not provide transferable insight into other force fields.

Ions Adsorbed at Amorphous Solid/Solution Interfaces Form Wigner Crystal-like Structures.

When a surface is immersed in a solution, it usually acquires a charge, which attracts counterions and repels co-ions to form an electrical double layer. The ions directly adsorbed to the surface are referred to as the Stern layer. The structure of the Stern layer normal to the interface was described decades ago, but the lateral organization within the Stern layer has received scant attention. This is because instrumental limitations have prevented visualization of the ion arrangements except for atypical, model, crystalline surfaces. Here, we use high-resolution amplitude modulated atomic force microscopy (AFM) to visualize in situ the lateral structure of Stern layer ions adsorbed to polycrystalline gold, and amorphous silica and gallium nitride (GaN). For all three substrates, when the density of ions in the layer exceeds a system-dependent threshold, correlation effects induce the formation of close packed structures akin to Wigner crystals. Depending on the surface and the ions, the Wigner crystal-like structure can be hexagonally close packed, cubic, or worm-like. The influence of the electrolyte concentration, species, and valence, as well as the surface type and charge, on the Stern layer structures is described. When the system parameters are changed to reduce the Stern layer ion surface excess below the threshold value, Wigner crystal-like structures do not form and the Stern layer is unstructured. For gold surfaces, molecular dynamics (MD) simulations reveal that when sufficient potential is applied to the surface, ion clusters form with dimensions similar to the Wigner crystal-like structures in the AFM images. The lateral Stern layer structures presented, and in particular the Wigner crystal-like structures, will influence diverse applications in chemistry, energy storage, environmental science, nanotechnology, biology, and medicine.

Polyepichlorohydrin grafted poly(phenylene oxide) to construct hydrophilic and hydrophobic microphase separation anion exchange membrane

An anion exchange membrane (QAPECH-g-PPO) with polyepichlorohydrin (PECH) as the main chain and poly(phenylene oxide) (PPO) as the side chain was prepared by Williamson etherification reaction. Atomic force microscopy (AFM) and small angle X-ray scattering (SAXS) characterization indicate that PECH grafted with PPO can effectively form a hydrophilic and hydrophobic phase separation structure. The amount of and molecular weight of PPO grafted has different effects on the membrane properties. As the amount of PPO grafted increases, the tensile strength of the membrane gradually increases. When the amount of PPO grafted exceeds 44%, the excessive hydrophobic phase prevents the formation of continuous ionic channels in the hydrophilic phase, leading to a significant decrease in ionic conductivity. When the amount of PPO is 38%, the ionic conductivity can reach 72 mS cm−1 (80 °C), while the swelling ratio is only 15%. Moreover, higher molecular weight PPO at 38% amount improves tensile strength of QAPECH-g-PPO membrane. The higher the molecular weight of PPO, the more stable the π - π stacking structure is formed, leading to more aggregation of hydrophobic phases in the anion exchange membrane and weakened constraints on ion clusters. Therefore, the water absorption and ion conductivity slightly increase.

Investigation of radiation shielding and optical properties of neodymium doped Bismuth Boro tellurite glasses for solid state device applications

In this work, a variety of glass samples with different chemical profiles for optical applications were synthesized, and characterized. The thermal properties of the prepared glass are investigated through Differential Thermal Analysis (DTA) and we have observed the endothermic peak at 894.9 °C and exothermic peak at 1066 °C. The optical properties were investigated using a UV–Visible–NIR Spectrophotometer, and the radiation shielding properties were reported using the Phy-X/PDS software. The optical property results show that when the amount of Nd3+ ions in a glass structure grows, the oscillator strengths also increase. The high emission cross-section and excellent quantum efficiency indicate that glass has the potential for compact 1.06 μm laser applications. The Photoluminescence (PL) analysis of Nd3+ ions doped prepared glass samples are recorded at 808 nm laser diode. The emission spectra for every Nd3+ ion concentration exhibit three distinct emission peaks at wavelengths of 902 nm, 1064 nm, and 1339 nm. The investigation of luminescence kinetics revealed the development of neodymium ion clusters commencing at a neodymium concentration of 1.006 × 1020cm−3. Furthermore, we noticed that the addition of Nd2O3 increased the mass attenuation coefficient and effective atomic number of the glass samples. In terms of the glasses' ability to absorb charged particles, the Nd2O3 addition also made a difference in Half Value Layer, Mean Free Path, and Effective atomic number. The research shows that the glass samples are non-toxic, visible light transparent, and radiation-efficient.

Entropy measures of the metal–organic network via topological descriptors

Abstract A family of chemical compounds known as metal–organic networks (MONs) is composed mainly of clusters of metal ions with organic ligands. It can increase volatility or make substances soluble in organic solvents. By using these salient features, organic compounds generate applications in material sciences for sol–gel processing. A graph’s entropy is utilized as a complexity indicator and is interpreted as the structural information content of the graph. Investigating the entropies of relationship systems is a common occurrence in discrete mathematics, computer science, information theory, statistics, chemistry, and biology. In this article, we investigated the degree-based entropies: geometric arithmetic entropy, atom bond connectivity entropy, general Randic′ entropy, and general sum connectivity entropy for MONs. Furthermore, we created tables for all expressions by using 1–10 values for the s s parameter of these entropies.

Time‐of‐flight secondary ion mass spectrometry and X‐ray photoelectron spectroscopy protocol for the analysis of organic multilayers

With the development in the early 2000s of new cluster ion sputtering sources, a reliable analysis of organic multilayers and interfaces has become possible. Nowadays, time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) and X‐ray photoelectron spectroscopy (XPS) depth profiling are routinely used to investigate organic stacks. However, analysis beams can cause bond scission or beam‐induced degradations that accumulate in buried layers. We developed a correlative protocol that minimises damages related to analysis beams. It uses a shallow angle bevel crater fabricated inside the ToF‐SIMS analysis chamber. With this preparation method, the in‐depth information is displayed over the surface of the bevel crater. XPS profiles and high‐resolution spectra paired with ToF‐SIMS images enable an easy identification of the organic layers and complete understanding of their chemistry. The reduction of beam‐induced degradation is achieved by minimising the acquisition times, therefore beam exposure on materials. Finally, an important advantage of this preparation method is that the analysis can be performed on exactly the same spot by multiple techniques. Several ToF‐SIMS and XPS acquisitions can be carried out with various parameters (investigation of backscattered Arn+ cluster ion fragments, tandem MS imaging…) as well as analysis with other techniques that possess limitations in spatial resolution and/or inaptitude to probe buried layers such as Raman or AFM.

Lipidomic Phenotyping Of Human Small Intestinal Organoids Using Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging.

In the past decade, interest in organoids for biomedical research has surged, resulting in a higher demand for advanced imaging techniques. Traditional specimen embedding methods pose challenges, such as analyte delocalization and histological assessment. Here, we present an optimized sample preparation approach utilizing an Epredia M-1 cellulose-based embedding matrix, which preserves the structural integrity of fragile small intestinal organoids (SIOs). Additionally, background interference (delocalization of analytes, nonspecific (histological) staining, matrix ion clusters) was minimized, and we demonstrate the compatibility with matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). With our approach, we can conduct label-free lipid imaging at the single-cell level, thereby yielding insights into the spatial distribution of lipids in both positive and negative ion modes. Moreover, M-1 embedding allows for an improved coregistration with histological and immunohistochemical (IHC) stainings, including MALDI-IHC, facilitating combined untargeted and targeted spatial information. Applying this approach, we successfully phenotyped crypt-like (CL) and villus-like (VL) SIOs, revealing that PE 36:2 [M - H]- (m/z 742.5) and PI 38:4 [M - H]- (m/z 885.5) display higher abundance in CL organoids, whereas PI 36:1 [M - H]- (m/z 863.6) was more prevalent in VL organoids. Our findings demonstrate the utility of M-1 embedding for advancing organoid research and unraveling intricate biological processes within these in vitro models.

Concentration dependent cyan emission by europium‐doped borosilicate glasses

AbstractAt present, doping of different alkaline‐earth metal ions is mainly used to tune the emission peak of europium (Eu) ions in glasses. However, the optimization of Eu‐doped glasses is hindered due to limited discussion on the relationship between local glass network structure, concentration of Eu ion dopants, and visible light emission by Eu ions. In this study, we prepared two series of borosilicate glasses doped with Eu ions, by varying the ratio of SiO2 to B2O3 and adjusting the concentration of Eu ion dopants to obtain cyan emission. The optical properties, structure, and differential scanning calorimetry (DSC) of the investigated glasses were systematically studied. With gradual increase in the content of SiO2, red shifting from 471 nm to 492 nm was observed under excitation at 410 nm, with the introduction of Eu2O3 also causing a redshift from 471 nm to 488 nm. The spectral results also revealed that under excitation at 410 nm all the glass samples exhibited cyan emission, with the optimal cyan peak at 492 nm (Si‐45) and the strongest cyan emission at Eu‐0.4 (480 nm). By adjusting the concentration ratios of Si to B in europium‐doped borosilicate glass, it was observed that by altering the [SiO4] tetrahedra, [BO4] tetrahedra, and [BO3] triangles within the glass ultimately cyan emission can be achieved. By varying the doping concentration of Eu ion to change the degree of local Eu ion clustering in the glass system, cyan emission can be achieved by tuning the emission peak.

Direct identification of interfacial degradation in blue OLEDs using nanoscale chemical depth profiling

Understanding the degradation mechanism of organic light-emitting diodes (OLED) is essential to improve device performance and stability. OLED failure, if not process-related, arises mostly from chemical instability. However, the challenges of sampling from nanoscale organic layers and interfaces with enough analytical information has hampered identification of degradation products and mechanisms. Here, we present a high-resolution diagnostic method of OLED degradation using an Orbitrap mass spectrometer equipped with a gas cluster ion beam to gently desorb nanometre levels of materials, providing unambiguous molecular information with 7-nm depth resolution. We chemically depth profile and analyse blue phosphorescent and thermally-activated delayed fluorescent (TADF) OLED devices at different degradation levels. For OLED devices with short operational lifetimes, dominant chemical degradation mainly relate to oxygen loss of molecules that occur at the interface between emission and electron transport layers (EML/ETL) where exciton distribution is maximised, confirmed by emission zone measurements. We also show approximately one order of magnitude increase in lifetime of devices with slightly modified host materials, which present minimal EML/ETL interfacial degradation and show the method can provide insight for future material and device architecture development.

Poly(aryl ether sulfone ketone) with densely sulfonated structural units facilitate microphase separation to promote proton transport

The development of high-performance and low-cost membrane materials is crucial for proton exchange membrane fuel cells. To improve the proton conductivity, we designed a novel multiple phenyls monomer. Then, we synthesize a series of sulfonated poly(aryl ether sulfone ketone) membranes (SPAESK-x). The hydrophilic groups are densely distributed in units after sulfonation, which can form large hydrophilic ion clusters and provide more connected channels for proton transport. The large hydrophilic ion clusters facilitate the separation of hydrophilic and hydrophobic phases to form wider proton transport channels. The SPAESK-15 membrane achieves a high proton conductivity (181.0 mS cm-1) at 80 °C. The novel monomer and polymers are budget and simple to synthesize, offering the possibility of large-scale preparation. Overall, the novel structure has the potential to develop high-performance electrolyte materials.