Abundant Ions Research Articles

Analysis of O-acetylated sialic acids by 3-nitrophenylhydrazine derivatization combined with LC-MS/MS.

Sialic acids are a family of monosaccharides that share a nine-carbon backbone and a carboxyl group. A recent derivatization method based on 3-nitrophenylhydrazine (3-NPH) provides a mild chemical labeling technique for biomolecules containing carbonyl or carboxyl groups. In this study, we utilized 3-NPH to label sialic acids via a two-step derivatization process. The derivatized species can produce a common reporter ion corresponding to C1-C3 with two labels, and a fragment differentiating between Neu5Ac, Neu5Gc, and KDN. This method is compatible with O-acetylated sialic acids and provides high sensitivity to Neu5Gc and KDN, and since the utilization of dual labeling significantly enhances the hydrophobicity of derivatives, it can effectively mitigate matrix effects when combined with parallel reaction monitoring technology. Negative-ion tandem mass spectrometry (MS/MS) analysis reveals a distinctive fragmentation profile for the 4-O-acetylated species, while the other sialic acids yield similar MS/MS spectra with a high abundance of reporter ions. Using the reporter ion as a transition, this analytical strategy is effective for analyzing complex biological samples. For example, it was successfully employed to quantify sialic acids in the intestinal tissues of several carp species, demonstrating its potential in sialylation research.

Enhanced carboxylation of furoic salt with CO2 by ZnCl2 coordination for efficient production of 2,5-furandicarboxylic acid.

C-H carboxylation of furoic acid (FA) with CO2 is an atom-efficient strategy to produce 2,5-furandicarboxylic acid (2,5-FDCA) from lignocellulose. The existing carbonate-promoted CO2 carboxylation processes rely on the use of large amounts of expensive Cs2CO3 as a deprotonating reagent and molten salt. Substitution of Cs with other cheap and abundant alkali ions (such as K and Na) can reduce the use of Cs, but it faces the problem of a low yield of 2,5-FDCA. This study found that the addition of catalytic amounts of ZnCl2 as a Lewis acid can increase the yield of 2,5-FDCA in the CO2 carboxylation reaction of Na/K-FA in a molten salt reaction system. 1H NMR analysis and DFT calculations confirmed that ZnCl2 coordinates with the furan ring through electron transfer from the conjugated furan ring to Zn2+, thereby activating the H at the C5 position of Na/K-FA. This coordination lengthened the C5-H bond and lowered its heterolytic dissociation energy, making it more susceptible to being deprotonated by CO32- and subsequently carboxylated by CO2. The developed Lewis acid coordination strategy provides a new idea for the efficient construction of C-C bonds between CO2 and aromatics through carbonate-promoted C-H carboxylation.

Heterogeneous solvent-metal-free aerobic oxidation of alcohol under ambient conditions catalyzed by TEMPO-functionalized porous poly(ionic liquid)s.

Heterogeneous solvent-metal-free aerobic oxidation of alcohols under ambient conditions is interesting but remains a significant challenge. Herein, a series of porous TEMPO-functionalized poly(ionic liquid)s (TEMPO-PILs) featuring a pure polycationic framework were successfully developed through the free radical polymerization of the ionic liquid 3-(2-chloroacetic acid-2,2,6,6-tetramethyl-1-oxo-4-piperidyl)-1-vinylimidazolium chloride and bis-vinylimidazolium bromide salt. Characterizations revealed that the obtained TEMPO-PILs possessed a high TEMPO density, abundant bromide ions, and a tunable porous structure, which enabled them to serve as solvent-free heterogeneous organocatalysts for the metal-free aerobic oxidation of benzyl alcohol under ambient conditions, exhibiting high catalytic activity and stable recyclability. A high yield of 99% coupled with a turnover frequency (TOF) of 13.3 h-1 was obtainable, which is higher than most of the reported TEMPO-based heterogeneous catalysts, even superior to homogeneous TEMPO-functionalized ionic liquids. Furthermore, a broad range of alcohols were effectively converted into their corresponding ketones and aldehydes. A possible reaction mechanism is proposed for understanding the catalytic oxidation behavior, indicative of the synergistic effect of TEMPO moieties and bromide ions.

Highly Strong, Tough, and Cryogenically Adaptive Hydrogel Ionic Conductors via Coordination Interactions.

Despite the promise of high flexibility and conformability of hydrogel ionic conductors, existing polymeric conductive hydrogels have long suffered from compromises in mechanical, electrical, and cryoadaptive properties due to monotonous functional improvement strategies, leading to lingering challenges. Here, we propose an all-in-one strategy for the preparation of poly(acrylic acid)/cellulose (PAA/Cel) hydrogel ionic conductors in a facile yet effective manner combining acrylic acid and salt-dissolved cellulose, in which abundant zinc ions simultaneously form strong coordination interactions with the two polymers, while free solute salts contribute to ionic conductivity and bind water molecules to prevent freezing. Therefore, the developed PAA/Cel hydrogel simultaneously achieved excellent mechanical, conductive, and cryogenically adaptive properties, with performances of 42.5 MPa for compressive strength, 1.6 MPa for tensile strength, 896.9% for stretchability, 9.2 MJ m-3 for toughness, 59.5 kJ m-2 for fracture energy, and 13.9 and 6.2 mS cm-1 for ionic conductivity at 25 and -70 °C, respectively. Enabled by these features, the resultant hydrogel ionic conductor is further demonstrated to be assembled as a self-powered electronic skin (e-skin) with high signal-to-noise ratio for use in monitoring movement and physiological signals regardless of cold temperatures, with hinting that could go beyond high-performance hydrogel ionic conductors.

Isolation and Identification of Phosphate-solubilizing Bacteria in the Rhizosphere of Robinia pseudoacacia on the Loess Plateau and Verification of Phosphate Solubilization Capacity.

The Loess Plateau is one of the key areas for soil and water erosion control in China. Planting vegetation, such as Robinia pseudoacacia, is one of the mainstream methods to prevent soil and water erosion. However, the combination of abundant calcium ions and phosphate in the soil of the Loess Plateau limits the phosphorus nutrition of plants. In the present study, soil samples were collected under the R. pseudoacacia forest, from which two PSB strains with efficient phosphate solubilization capacities, named PSB2 and PSB7, were isolated and screened. The dissolved phosphate concentrations of their culture media were 9.68-fold and 11.61-fold higher, respectively, than that of the control group. After identification, PSB2 was classified as Pseudomonas and PSB7 as Inquilinus. This is the first time that Inquilinus has been isolated as a PSB from calcareous soil in the Loess Plateau. We then investigated the effects of different growth conditions on their phosphate solubilization capacities. Both strains effectively utilized glucose and ammonium nitrogen while maintaining high phosphate solubilization efficiency. In addition, PSB2 preferred to survive under neutral conditions and PSB7 under acidic conditions. Pot experiments indicated that the inoculation with PSB7 significantly increased the phosphorus content in the roots of R. pseudoacacia. These results imply the potential of this PSB as a phosphorus biofertilizer for R. pseudoacacia, which may be beneficial for soil and water management on the Loess Plateau.

Selectively "size-excluding" water molecules to enable a highly reversible zinc metal anode.

Significant water-related side reactions hinder the development of highly safe, low-cost aqueous zinc metal batteries (AZMBs) for grid-scale energy storage. Herein, by regulating the length of alkyl chains, we successfully adjust interstitial voids between the polymer chains of a metal soap interface between 1.48 Å (size of a zinc ion) and 4.0 Å (size of a water molecule). Therefore, water molecules are selectively "size-excluded," while smaller zinc ions are permitted to pass through. Consequently, water-related side reactions (including hydrogen evolution and corrosion) could be effectively inhibited. Furthermore, abundant zinc ion tunnels accompanied with zincophilic components facilitate the homogenization of the Zn2+ flux, thus preventing dendrite growth. Therefore, the Zn symmetric cell shows a lifespan of approximately 10 000 cycles at 20 mA cm-2 and 1 mA h cm-2, and the Zn//Na5V12O32 (NVO) full cell delivers much better cycling stability with much higher capacity retention of around 93% after 2000 cycles at 2 A g-1 compared to its bare Zn counterpart (19%). This work provides valuable insights for the utilization of metal soap interfaces and regulation of their channel size between perpendicular alkyl chains to realize precise water shielding, which is not only applicable in ZMBs but also in other aqueous batteries.

Strong, tough and conductive single-network hydrogels based on deswelling and the salting-out effect.

In recent years, the continuous attention given to increasing the fracture toughness and Young's modulus of polymeric gels has gradually shifted from toughening strategies on double-network (DN) gels to single-network (SN) gels. The salt-soaking method has been adopted to realize the toughening of SN gels through the salting-out effect and deswelling, constructing dense network structures with simultaneously precipitated polymer chains and cross-links. By comparing the mechanical properties between salt-treated hydrogels and air-dried hydrogels, the increased polymer chain concentration is proved to promote energy transfer by enlarging the dissipation region size due to the unwinding and slippage of coiled chains during stretching. The newly formed cross-link points in salt-treated hydrogels are considered to consume more deformation energy during stretching. The synergistic effect in energy transfer and dissipation arising from increases in polymer fraction and cross-linking plays an indispensable role in toughening SN hydrogels. In addition, the soaking process introduces abundant free ions to endow hydrogels with prominent conductivity. Thus, this salt-soaking method provides a general approach to synthesize strong, tough and conductive hydrogels with applications in flexible electrical devices.

Utilising Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to track the oxidation of lignin by an alkaliphilic laccase.

Lignin is a complex heteroaromatic polymer which is one of the most abundant and diverse biopolymers on the planet. It comprises approximately one third of all woody plant matter, making it an attractive candidate as an alternative, renewable feedstock to petrochemicals to produce fine chemicals. However, the inherent complexity of lignin makes it difficult to analyse and characterise using common analytical techniques, proving a hindrance to the utilisation of lignin as a green chemical feedstock. Herein we outline the tracking of lignin degradation by an alkaliphilic laccase in a semi-quantitative manner using a combined chemical analysis approach using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to characterise shifts in chemical diversity and relative abundance of ions, and NMR to highlight changes in the structure of lignin. Specifically, an alkaliphilic laccase was used to degrade an industrially relevant lignin, with compounds such as syringaresinol being almost wholly removed (95%) after 24 hours of treatment. Structural analyses reinforced these findings, indicating a >50% loss of NMR signal relating to β-β linkages, of which syringaresinol is representative. Ultimately, this work underlines a combined analytical approach that can be used to gain a broader semi-quantitative understanding of the enzymatic activity of laccases within a complex, non-model mixture.

Multiple ion isolation and accumulation events for selective chemical noise reduction and dynamic range enhancement in MALDI imaging mass spectrometry.

Abundant chemical noise in MALDI imaging mass spectrometry experiments can impede the detection of less abundant compounds of interest. This chemical noise commonly originates from the MALDI matrix as well as other endogenous compounds present in high concentrations and/or with high ionization efficiencies. MALDI imaging mass spectrometry of biological tissues measures numerous biomolecular compounds that exist in a wide range of concentrations in vivo. When ion trapping instruments are used, highly abundant ions can dominate the charge capacity and lead to space charge effects that hinder the dynamic range and detection of lowly abundant compounds of interest. Gas-phase fractionation has been previously utilized in mass spectrometry to isolate and enrich target analytes. Herein, we have characterized the use of multiple continuous accumulations of selected ions (Multi CASI) to reduce the abundance of chemical noise and diminish the effects of space charge in MALDI imaging mass spectrometry experiments. Multi CASI utilizes the mass-resolving capability of a quadrupole mass filter to perform multiple sequential ion isolation events prior to a single mass analysis of the combined ion population. Multi CASI was used to improve metabolite and lipid detection in the MALDI imaging mass spectrometry analysis of rat brain tissue.

Selective fluoride sensing by a novel series of lanthanide-based one-dimensional coordination polymers through intramolecular proton transfer.

A novel series of one-dimensional coordination polymers (CPs) is achieved via a facile one-pot synthesis strategy employing the nitrate salts of trivalent lanthanides, a pentadentate chelating ligand, and triphenylphosphine oxide at a controlled stoichiometry under ambient conditions. All the CPs are characterized comprehensively using spectroscopic, X-ray crystallographic and magnetometric studies. The CPs are found to be thermally stable up to a significantly high temperature and resistant to water for an indefinite time. They are photoactive and exhibit selective fluoride ion (F-) sensing with excellent efficiency both colorimetrically and fluorimetrically in the solid-state as well as in solution. The presence of F- concomitantly sensitizes the photoluminescence enhancement and visual decolourization of the CPs in solution owing to the ground-state intra-molecular proton transfer. The photophysical response of the CPs to F- in solution was found to be instantaneous (<30 s). The sensitivity of detection is observed to be significantly high over a wide range of F- concentrations, covering the beneficial and detrimental domains of F- concentrations in drinking water. The limit of detection (LoD) under ambient conditions was found to be in the micromolar (μM) range-the best being 0.22 μM found using UV-vis spectrometry and 7.5 μM using fluorimetry. In comparison, the USEPA standard cut-off for the upper limit of F- concentration in drinking water is 211 μM, and the LoD of measuring F- concentration using the USEPA standard method using a fluoride-selective electrode is 26.3 μM. The CPs display markedly high selectivity toward F- with negligible-to-no interference from the commonly abundant ions (Cl-, Br-, I-, CH3CO2-, CO32-, SO42-, HPO42-, NH4+, Na+, K+, Mg2+, and Ca2+) in terms of UV-vis spectral change. Moreover, they also exhibit solid-state IR-spectrometric sensitivity towards F- under ambient conditions.

Study of Ionic Migration in Sea Water through Directional Freezing

The six most abundant ions present in seawater are chloride (Cl−), sodium (Na+), sulfate (SO42-), magnesium (Mg2+), calcium (Ca2+), and potassium (K+). By weight these ions make up almost 99 percent of the salinity of sea water. Removal of these ions or desalination makes the sea water useable. In the present work migration of these common and abundantly found ions in sea water has been studied when the water samples were subjected to directional freezing vertically as well as horizontally. Water samples collected from Arabian Sea were frozen in two partially insulated devices under different modes. The samples were placed in a freezer at different temperature conditions and all the six ions present in sea water were estimated in different fractions of ice extracted from various locations of frozen mass obtained after freezing. The fractions collected from the top of vertical device and from the periphery of the horizontal device were found to be completely decontaminated and free from the ions. Most of the ions were found concentrated at the bottom of the vertical device and in the center of horizontal device. The directional freezing method was found simple, inexpensive and free of chemicals method which can be effectively employed for the desalination of sea water particularly in the regions where cold energy is naturally available

Derivatization-Enhanced Analysis of Glucocorticoids for Structural Characterization by Gas Chromatography-Orbitrap High-Resolution Mass Spectrometry.

Glucocorticoids are classified in section S9 of the Prohibited List of the World Anti-Doping Agency, due to a potential risk to improving physical performance and causing harm to the health of athletes. Based on the similar physiological actions of glucocorticoids, both differentiating known glucocorticoids and identifying unknown glucocorticoids are important for doping control. Gas chromatography coupled with mass spectrometry plays an important role in structural characterization because of abundant structural diagnostic ions produced by electron ionization. It also provides a chance to study the fragmentation patterns. Thus, an enhanced derivatization procedure was optimized to produce trimethylsilylated glucocorticoids and structural diagnostic ions of nineteen trimethylsilylated glucocorticoids were obtained by gas chromatography-orbitrap high-resolution mass spectrometry. In our study, glucocorticoids were classified as: 3-keto-4-ene, 1,4-diene-3-keto, 3α-hydroxy with saturated A-ring, 21-hydroxy-20-keto and halo substituent glucocorticoids based on their structural difference. Structural diagnostic ions that contributed to structural characterization were specifically presented and the fragment patterns were demonstrated according to the above categories. This study not only gave new insights into the structural characterization of these glucocorticoids but also provided evidence for tracing unknown glucocorticoids or chemically modified molecules.

Facile synthesis of robust polyethyleneimine incorporated chitosan composite hydrogel for efficient enrichment of uranium(VI) in aqueous solution

The development of polymer hydrogel with abundant ion diffusion paths is needed to address sustainable energy supply and ecological security. Herein, a robust chitosan-based polymer hydrogel with superior structural stability and sufficient active sites was fabricated by incorporating polyethyleneimine into chitosan for efficient enrichment of uranium(VI). The as-prepared chitosan-based polymer hydrogel has a maximum uranium adsorption capacity of 291.75 mg-U/g at pH= 6, together with relatively good selectivity to uranium(VI). The adsorption process was described well with the pseudo-second-order kinetic model and Langmuir isotherm model. The main adsorption mechanism was related to the complexation of uranyl ions with the amino and hydroxyl groups. The chitosan-based polymer hydrogel, with the merits of facile preparation, easy solid-liquid separation, eco-friendliness and cyclic utilization highlights its promising application in uranium removal and recovery from uranium-containing wastewater.

Structural confirmation of position isomers 2‐(2‐methylaminoprolyl)benzofuran and 5‐(2‐methylaminopropyl)benzofuran: a combined mass spectrometric and computational study

AbstractRationalePhenylethylamines are one of the most common types of new psychoactive substances, following synthetic cannabinoids and synthetic cathinones. They are regulated in many countries because of their strong hallucinogenic effects, which can cause serious nerve damage. There is a wide variety of phenylethylamines, exhibiting rapid renewal and extremely similar structures, therefore accurate qualitative analysis of isomers is a difficult problem in current drug analysis.MethodsThe dissociation pathways of the position isomers 2‐(2‐methylaminoprolyl)benzofuran (2‐MAPB) and 5‐(2‐methylaminopropyl)benzofuran (5‐MAPB) were investigated by gas chromatography–mass spectrometry and liquid chromatography coupled to high‐resolution quadrupole Orbitrap MS. The dissociation patterns of the phenethylamine‐based designer drugs 2‐MAPB and 5‐MAPB were explored and extended in this work based on MS combined with density functional theory studies.ResultsFor electron ionization mass spectrometry (EI‐MS) analysis, the dissociation patterns of 2‐MAPB were similar to those of 5‐MAPB. For electrospray ionization mass spectrometry (ESI‐MSn) analysis, the hydrogen atom on amino group was facile to form a intramolecular hydrogen bond with the oxygen atom on the parent nucleus of benzofuran in the structure of 2‐MAPB, leading to higher abundance of the product ion at m/z 58. However, there was a conjugated system between the positive charge formed by the cleavage of the 5‐MAPB side chain and the benzofuran ring, enabling the 5‐MAPB to generate a product ion at m/z 131. Computational study showed that energy barrier and spin density difference distribution jointly control the selective dissociation in EI‐MS, while different types of orbital interaction induced by intramolecular hydrogen bond led to different dissociation results in ESI‐MSn.ConclusionsThese different dissociation patterns could be used to distinguish 2‐MAPB from 5‐MAPB. This could assist forensic laboratories in the differentiation and characterization of potential isomers in these kinds of compounds, especially in mixtures.

Study on Factors Affecting Water Resistance of Titanium Negative Electrode Materials for Na Batteries

【Background】 In recent years, sodium-ion batteries, which use abundant Na ions as charge carries, have been attracting attention as an alternative to lithium-ion batteries. Sodium-ion batteries are expected to be used as large-scale energy storage devices due to moderate energy density, but air storage stability of the layered oxides is an important issue to be considered. In this study, air storage stability of titanium layered oxides with different chemical compositions and structures, P2 Na2/3Cr1/3Mg1/6Ti1/2O2, P2 Na0.67Li0.22Ti0.78O2, P2 Na2/3Cr2/3Ti1/3O2, and P3 Na0.58Cr0.58Ti0.42O2, is systematically examined, from which the factors affecting air storage stability is discussed.【Results and Discussion】 Figure 1 shows the X-ray diffraction patterns of P2 Na2/3Cr1/3Mg1/6Ti1/2O2 (P2 NaCrMgTi) before and after soaking in water for 30 minutes (and then dried after vacuum filtration). After the soaking test, although the profile of diffraction lines is broadened, its original crystal structure is retained. On the other hand, for P2 Na2/3Cr2/3Ti1/3O2 (P2-NaCrTi), and P3-Na0.58Cr0.58Ti0.42O2 (P3-NaCrTi), hydrated phases are formed. Figure 2 compares charge/discharge curves of these layered oxides after the soaking test. Electrodes with P2-NaCrMgTi, which have a minor change in crystal structure, shows the deterioration in initial Coulomb efficiency, but no reduction in discharge capacity is evidenced. In contrast, both P2-NaCrTi and P3-NaCrTi, where the hydrated phases were formed, shows the degradation in electrode reversibility. From these results, air storage stability of these different layered oxides is discussed in detail. Figure 1

Characterization of Sulfur-Rich Microbial Organic Matter in Jurassic Carbonates Using Laser-Assisted Mass Spectrometry.

Laser desorption-ionization mass spectrometry (MS) shows great potential for in situ molecular analysis of planetary surfaces and microanalysis of space-returned samples or (micro)fossils. Coupled with pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) in ESA's ExoMars project, this technique could help assess further the origin of sulfur-bearing organic matter (OM) recently detected on Mars. To unravel this potential, we analyzed sulfurized microbial OM from ca. 150 million year-old carbonates with laser desorption-ionization mass spectrometry (single- and two-step: LDI-MS and L2MS), in comparison with time-of-flight secondary-ion mass spectrometry (ToF-SIMS), gas chromatography-mass spectrometry (GC-MS), and Py-GC-MS. We show that LDI-MS and L2MS readily detect sulfur-bearing moieties such as (alkyl)thiophenes and (alkyl)benzothiophenes. The mineral matrix, however, made the identification of sulfur-bearing molecules challenging in our L2MS experiment. The dominance of small aromatic hydrocarbons (≤14 carbons) in the LDI-MS and L2MS of the extracted soluble and insoluble OM and of the bulk rock is consistent with the low thermal maturity of the sediment and contrasts with the predominance of larger polycyclic aromatic structures commonly observed in meteorites with these techniques. We detected inorganic ions, in particular VO+, in demineralized OM that likely originate from geoporphyrins, which derive from chlorophylls during sediment diagenesis. Finally, insoluble OM yielded distinct compositions compared with extracted soluble OM, with a greater abundance of ions of mass-to-charge ratio (m/z) over 175 and additional N-moieties. This highlights the potential of laser-assisted MS to decipher the composition of macromolecular OM, in particular to investigate the preservation of biomacromolecules in microfossils. Studies comparing diverse biogenic and abiogenic OM are needed to further assess the use of this technique to search for biosignatures.

Analysis of transferrin in urine in patients with bladder cancer using nanobodies

It is known that the saturation ratio of transferrin (Tf) with iron in human blood is an important clinical parameter. Specific antibodies can be used to analyze subtle changes in the relative abundance of different forms of transferrin potentially associated with a pathological process. Recently, the authors of this study were able to obtain and characterize highly specific single-domain antibodies (nanobodies) that predominantly recognize the iron-saturated (holo-Tf) or iron-unsaturated (apo-Tf) form of transferrin. In this work, under conditions closer to physiological than in previous experiments, we further demonstrated that these unique nanobodies have extremely high differential binding specificity for different forms of Tf in different human biological fluids. Using these nanobodies, we were able to analyze for the first time the relative abundance of transferrin forms in urine samples from patients with bladder cancer (BC). We have shown that an increase in the concentration of total Tf in urine samples normalized for creatinine is associated with the degree of progress and growth of malignancy of BC. In the samples of healthy donors and in the early stages of BC (G1), Tf is detected in much smaller amounts (compared to later stages) and only with additional concentration of the studied samples. For most of the studied urine samples from BC patients, it is expected (as previously shown in the case of Tf in the blood of terminal ovarian cancer patients) that the concentration of apo-Tf is clearly higher than holo-Tf, especially in the case of the most advanced muscle-invasive BC. It was a surprise for us that approximately equal amounts of apo-Tf and “holo-Tf” were found in the urine samples of some patients with BC. We hypothesized that the “holo-Tf” fraction in this case can be largely represented by “secondary complexes” formed by apo-Tf in combination with ions other than Fe3+, which accumulate in the urine of some cancer patients and are able to bind to apo-Tf, changing its conformation towards holo-Tf. Using inductively coupled plasma ionization mass spectroscopy (ICP-MS), we obtained the first results confirming our hypothesis. The “holo-Tf” preparation in these urine samples was found to be highly enriched in zinc and nickel. Also in this preparation, a relative enrichment in cadmium is observed, but it is present in much lower concentrations. The data obtained indicate that the nanobody used, recognizing predominantly the iron-saturated form of transferrin (holo-Tf), is also capable of binding transferrin in association with other metal ions that are different from iron. This ability could potentially open up new possibilities in studies of the relative abundance of various metal ions in association with transferrin in human biological fluids in normal and pathological conditions.

Drop That Activation Energy: Tetragonal to Cubic Transformations in Na3PS4−xSex for Solid State Sodium Ion Battery Materials

AbstractSodium‐containing chalcogenide materials are emerging as a class of solid electrolytes for application in inexpensive all‐solid‐state sodium‐ion batteries due to their high ionic conductivity, abundance, and degree of synthetic and structural variability. Members of the solid solution Na3PS4−xSex, which are promising solid electrolytes for sodium‐ion batteries, are prepared by reaction at high temperature. With increasing substitution of S by Se, the structure transforms from tetragonal (space group P21c for x = 0, 1) to cubic (space group I3m for x = 2, 3, 4). Within the solid solution, the S and Se atoms are completely disordered in the environments around the P atoms, in accordance with a binomial distribution, as inferred by the 31P nuclear magnetic resonance (NMR) spectra. In 23Na NMR experiments conducted at different magnetic fields and temperatures, quadrupolar lineshapes are observed that are influenced by sodium ion dynamics; the activation energies decrease from 0.21 to 0.15 eV on progressing from the S‐ to the Se‐rich members. A dynamic model is proposed to account for the changes in the 23Na quadrupolar lineshapes by switching the orientations of the electric field gradient and chemical shift anisotropy tensors when Na+ ions hop to the four nearest Na sites.

CD8+ T Cells Keep Their (K+)urrency for Function.

CD8+ T-cell responses are influenced by ion abundance, which can widely vary within the tumor microenvironment. In this issue, Collier and colleagues investigated how intracellular versus extracellular potassium ion (K+) regulates intratumoral CD8+ T cells. They show that, while excessive extracellular K+ induces exhaustion, intracellular K+ is needed for protection from dysfunction. This work shows additional evidence that the regulation of CD8+ T-cell responses depends on a fine balance between intracellular and extracellular metabolite levels. See related article by Collier et al., p. 36 (2) .

Synthesis, Sensing Performance and DFT Studies of a Novel Coumarin-based Schiff Base As a Turn-on Fluorescence Probe for Zinc Ion Detection.

The design and development of novel efficient fluorescent chemical sensors for the selective detection of ions is currently of significant importance in supramolecular chemistry. Since zinc is a ubiquitous, indispensable and the second most abundant metal ion in the human body, developing chemosensors that can accurately discriminate between Zn2+ and Cd2+ ions has been a challenge due to their similar properties as they are in the same group of the periodic table. Therefore, a technique to trace and visualize free zinc ions is demanded. In this study, an innovative coumarin-based Schiff base (L) was synthesized and characterized by 1H NMR, 13C NMR and mass spectroscopy. A novel "Turn On" fluorescence chemosensor platform was developed for trace amounts of Zn2+ ions. The fluorescence Job's plot measurement was used to determine the complexation ratio between the probe and Zn2+ ion, which showed a maximum point indicating the formation of a ML2 adduct. Additionally, the geometrical parameters calculated using DFT and TD-DFT calculations were in close agreement with the experimentally observed values.