Alkaline water electrolysis provides a cost-efficient route for hydrogen production,thereby contributing to the reduction of fos-sil fuel dependence.This process involves two half-reactions-hydrogen evolution(HER)and oxygen evolution reactions(OER)-both of which require efficient catalysts to overcome slug-gish kinetics.

Fe-N-C catalysts have emerged as a promising substitute for the expensive Pt/C to boost the oxygen reduction reaction (ORR). However, conventional Fe-N4 active sites, which generally feature a low-spin configuration, strongly adsorb oxygen intermediates and necessitate structural optimization of the active sites for improved performance. Herein, graphitic nitrogen (NGC) adjacent to the Fe-N4 centers is straightforwardly introduced to modulate the spin state of Fe-N-C catalysts after elucidating the influence of nitrogen species on the Fe-N4 sites. Theoretical calculations demonstrate that the adjacent NGC can effectively regulate the spin state of the active Fe sites, which enables electron filling from Fe to the anti-bonding π* orbital of oxygen species and optimizes the *OH desorption for accelerated ORR. Inspired by this, such catalysts are cost-effectively prepared by a rational combination of electrospinning and controlled thermal annealing using inexpensive precursors. The optimal catalyst shows superior ORR activity to the benchmark Pt/C, and excellent durability, with a minor voltage decay of 11 mV after 10 000 cycles. The spin-state-promoted performance enhancement is confirmed by a series of in-situ characterizations. The remarkable performance of the optimized catalyst is further confirmed in Zn-air batteries (ZABs) with a peak power density of 225 mW cm-2. Moreover, quasi-solid ZABs using this catalyst realize excellent performance even under bending conditions and successfully power electronic devices, including a mobile phone and an electronic watch. This work correlates the spin state of catalysts and oxygen reduction performance, providing an alternative strategy for regulating the performance of electrocatalysts as well as promoting their application in wearable electronics.

Hard carbon (HC), a prime anode candidate for sodium-ion batteries, exhibits unresolved charge-state-microstructure debates reveal critical sodium storage mechanism gaps. This study employs electron paramagnetic resonance (EPR) spectroscopy as a principal characterization tool, capitalizing on its unique capability to probe electronic configurations and detect subtle structural transformations in carbon matrices. Through systematic EPR investigations of sodium storage dynamics in varied carbon architectures, the quasi-metallic state of sodium ions stored in closed pores exhibits distinct signal characteristics due to size effect-induced structural confinement, compared to surface storage mechanisms. Furthermore, the underappreciated influence of conductive carbon additives, a ubiquitous component in electrode formulations is specifically addressed, on spectroscopic interpretations. This findings reveal that sodium's distinctive storage states (ionic vs quasi-metallic) and their spatial distribution within carbon matrices induce quantifiable modifications in EPR spectral parameters, including characteristic linewidth broadening and lineshape evolution. The comparative analysis demonstrates that trace amounts (≤10 wt.%) of conductive additives can substantially distort ex situ EPR measurements, with interference patterns exhibiting strong material-dependent behavior. Therefore, the application of conductive additives demands rigorous consideration in EPR-based investigations of energy-storing carbon materials, given their methodological implications.

The mitotic spindle is a bipolar array of microtubules, radiating from the poles which each contain a centrosome, embedded in pericentriolar material. Two proteins, ch-TOG and TACC3, have multiple functions at the mitotic spindle due to operating either alone, together, or in complex with other proteins. To distinguish these activities, we need new molecular tools to dissect their function. Here, we present the structure of the α-helical bundle domain of ch-TOG that mediates its interaction with TACC3 and a structural model describing the interaction, supported by biophysical and biochemical data. We have isolated Affimer tools to precisely target the ch-TOG-binding site on TACC3 in live cells, which displace ch-TOG without affecting the spindle localization of other protein complex components. Inhibition of the TACC3–ch-TOG interaction led unexpectedly to fragmentation of the pericentriolar material in metaphase cells and delayed mitotic progression, uncovering a novel role of TACC3–ch-TOG in maintaining pericentriolar material integrity during mitosis to ensure timely cell division.

Electron paramagnetic resonance (EPR) spectroscopy in combination with site-directed spin labelling provides information on structure and dynamics of biomolecules. Increasing the availability of spin labels with different properties is an elegant way to foster a more accurate analysis of the EPR data in relation to the biological problem investigated. In this study, we present a comparative investigation of labelling efficiency, surface accessibility, site specificity and width of the distance distributions obtained on two proteins with the nitroxide-based bromoacrylaldehyde spin label (BASL) versus the two commercial spin labels MTSL (methanethiosulfonate spin label) and MAP (maleimido proxyl). Based on the predicted distances from a rotamer library approach and on the experimental distance distributions, BASL is shown to provide generally narrower distance distributions compared to the other nitroxide labels. The exquisite surface specificity of BASL with respect to MAP could be successfully exploited to selectively label surface cysteines in proteins containing a high number of native cysteines. In addition, the distinct site-reactivity of BASL and MAP towards two surface-exposed cysteines was leveraged for orthogonal labelling strategies with nitroxide and gadolinium labels.

Hard carbon is a promising negative electrode material for rechargeable sodium-ion batteries due to the ready availability of their precursors and high reversible charge storage. The reaction mechanisms that drive the sodiation properties in hard carbons and subsequent electrochemical performance are strictly linked to the characteristic slope and plateau regions observed in the voltage profile of these materials. This work shows that electron paramagnetic resonance (EPR) spectroscopy is a powerful and fast diagnostic tool to predict the extent of the charge stored in the slope and plateau regions during galvanostatic tests in hard carbon materials. EPR lineshape simulation and temperature-dependent measurements help to separate the nature of the spins in mechanochemically modified hard carbon materials synthesised at different temperatures. This proves relationships between structure modification and electrochemical signatures in the galvanostatic curves to obtain information on their sodium storage mechanism. Furthermore, through ex situ EPR studies we study the evolution of these EPR signals at different states of charge to further elucidate the storage mechanisms in these carbons. Finally, we discuss the interrelationship between EPR spectroscopy data of the hard carbon samples studied and their corresponding charging storage mechanism. Hard carbons are considered the most suitable negative electrode materials for Na-ion batteries. Here, authors use electron paramagnetic resonance spectroscopy to determine the spin nature of mechanochemically-modified hard carbons to predict their charge storage mechanism for sodium-ion batteries.

Ceiba pentandra (L.) Gaertn. (Bombacaceae) is popular for the quality of its wood. However, its leaf, stem bark and root bark have been popular in ethnomedicine and, apart from the inflorescence, have been subject of extensive phytochemical investigations. In this study, two compounds were isolated from the crude methanol extract of the inflorescence. Through data from UV, NMR, MS, electrochemical studies, differential scanning calorimetry, and thermogravimetric analysis, the structures were elucidated as 3-C-β-d-glucopyranosyl-1,3,6,7-tetrahydroxyxanthone (1) and 2-C-β-d-glucopyranosyl-1,3,6,7-tetrahydroxyxanthone (mangiferin, 2). They were assessed for antioxidant efficacy (DCFDA assay) and for anti-inflammatory efficacy using the lipopolysaccharide (LPS)-induced inflammation model in the RAW 264.7 macrophages (nitrite levels quantified, using Griess Assay, as surrogate for nitric oxide (NO)). Compound 1 (named ceibinin) was established as a novel positional isomer of mangiferin (2). While both 1 and 2 were antioxidant against basal and hydrogen peroxide (100 μM)-induced oxidative stress (6.25 μg/ml abrogated peroxide-induced oxidative stress), ceibinin (1) demonstrated no anti-inflammatory potential, unlike mangiferin (2) which, as previously reported, showed anti-inflammatory effect. Our work reports a positional isomer of mangiferin for the first time in C. pentandra and demonstrates how such isomerism could underlie differences in biological activities and thus the potential for development into therapeutics.

Developing high mass-loading electrodes is crucial for enhancing the energy density of current batteries, yet challenges such as poor rate performance and cycling instability must be addressed. Spin charge storage on transition metal nanoparticle surfaces, characterized by rapid charging and the absence of phase transitions, offers an ideal storage behavior for high mass-loading electrodes. In this study, electrospinning is utilized to fabricate free-standing carbon nanofibers incorporating Co nanoparticles for high-mass loading and high-performance anodes. The resulting anode, with a maximum mass loading of 6.8 mg cm-2, exhibits remarkable cycle stability and high-rate performance of 2 A g-1 at a capacity over 3 mAh cm-2, superior than reported results. Magnetometry and electron paramagnetic resonance spectroscopy are employed to monitor the charge storage mechanism of the Co@CNFs, involving both the reversible formation of a spin capacitance and the growth of radical anions in the solid electrolyte interface. Additionally, in situ X-ray diffraction and optical microscopy provide direct evidence of the absence of mechanical stress-induced phenomena within the spin charge process, attributed to high-rate capable lithium storage under high mass loading. The strategic approach presented herein offers a reliable methodology for engineering high-energy-density lithium-ion batteries. The spin charge storage mechanism induced by transition metal nanoparticles in lithium-ion batteries represents a zero-stress and no-phase transition storage process. Therefore, free-standing carbon nanofibers incorporating Co nanoparticles fabricated via the straightforward electrospinning technique are promising anodes for high-rate capable lithium storage under high mass loading. image

The build-up of elemental sulfur waste poses problems such that only the advancement of process and product design might act as a solution. Inverse vulcanisation, a process for the generation of high sulfur content polymeric materials may be one such resolution. However, a complete understanding of how these materials form is yet to be fully agreed in this emerging field. Herein is an investigation into the understanding of 'dark sulfur' - amorphous, unreacted sulfur, not incorporated into the polymer backbone - in an attempt to understand further the formation mechanisms behind inverse vulcanisation. This research posits theories regarding polymer formation, thermal rearrangement, and the actions of OH to control the degree of product crosslinking, in relation to the quantity of sulfur unreacted into the polymer structure. The detriments and benefits of this dark sulfur in relation to application and general usage are also investigated, showing that a high content of dark sulfur may encourage planktonic bactericidal activity, while also promoting safety considerations from generated species such as hydrogen sulfide and carbon disulfide, concluded as components of this dark sulfur.

An epoxy-functionalized beta type nanozeolite (BEA)/graphene oxide nanocomposite modified glassy carbon electrode (GCE/BEA/APTMS/GA/GO/NF) has been created for the differential pulse voltammetric determination of bisphenol E (BPE). The modified electrode presented an enhanced current response in comparison with bare GCE. A linear dependence of anodic peak current ( I p ) and scan rate (ν) was observed, which showed that the electrochemical process was adsorption-controlled. Differential pulse voltammetry (DPV) was employed and optimized for the sensitive determination of BPE. Under the optimized conditions, the anodic peak current was linearly proportional to BPE concentration in the range between 0.07 and 4.81 µM, with a correlation coefficient of 0.995 and limit of detection 0.056 μM (S/N = 3). The electrode showed good repeatability and storage stability, and a low response to interfering compounds. Comparison was made to the determination of bisphenol A. To confirm the electrode analytical performance, recovery tests were performed, and deviations lower than 10% were found. The BEA zeolite-GO nanocomposite proved to be a promising sensing platform for bisphenol determination. Graphical abstract

Purpurogallin (PPG), an orange-red crystalline compound from nutgalls and oak bark, is an exemplar of numerous, ubiquitous natural colorants, biosynthesized through oxidative dimerization-decarboxylation of phenolic compounds. It possesses antioxidant, anticancer, and anti-inflammatory effects. Herein, a robust method is presented to allow students to expediently make this interesting compound that contains a tropolone ring, whose identity initiated a paradigm shift in the understanding of aromaticity. 1D and 2D nuclear magnetic resonance (NMR) spectroscopic data (H-1, C-13-DEPT-Q HSQC, HMBC) were used to identify which protons are connected to carbon atoms. Fourier transform infrared spectroscopy (FT-IR), mass spectrometry, and X-ray diffraction were used to provide complementary information. Importantly, sufficient historical detail is given to provide a useful narrative that highlights the shift from deductive and synthetic proof of structural identity to modern methods of structural elucidation. As a minor, but important, aspect of iron gall inks, PPG links the work of important western historical documents from Da Vinci's Vitruvian Man to the United States Declaration of Independence. In the experience of the authors, such a pedagogic approach enlivens students with practical exercises which place them within the historical arc and reasoning of notable scientists, adding a sense of scientific discovery.

The protozoan parasite Trypanosoma cruzi is the causative agent of American trypanosomiasis, otherwise known as Chagas disease. To survive in the host, the T. cruzi parasite needs antioxidant defense systems. One of these is a hybrid heme peroxidase, the T. cruzi ascorbate peroxidase-cytochrome c peroxidase enzyme (TcAPx-CcP). TcAPx-CcP has high sequence identity to members of the class I peroxidase family, notably ascorbate peroxidase (APX) and cytochrome c peroxidase (CcP), as well as a mitochondrial peroxidase from Leishmania major (LmP). The aim of this work was to solve the structure and examine the reactivity of the TcAPx-CcP enzyme. Low temperature electron para-magnetic resonance spectra support the formation of an exchange-coupled [Fe(IV)=O Trp(233)(center dot+)] compound I radical species, analogous to that used in CcP and LmP. We demonstrate that TcAPx-CcP is similar in overall structure to APX and CcP, but there are differences in the substrate -binding regions. Furthermore, the electron transfer pathway from cytochrome c to the heme in CcP and LmP is preserved in the TcAPx-CcP structure. Integration of steady state ki-netic experiments, molecular dynamic simulations, and bio-informatic analyses indicates that TcAPx-CcP preferentially oxidizes cytochrome c but is still competent for oxidization of ascorbate. The results reveal that TcAPx-CcP is a credible cytochrome c peroxidase, which can also bind and use ascorbate in host cells, where concentrations are in the millimolar range. Thus, kinetically and functionally TcAPx-CcP can be considered a hybrid peroxidase.

Structural investigations of proteins and their biological complexes are now frequently complemented by distance constraints between spin labeled cysteines generated using double electron–electron resonance (DEER) spectroscopy, via site directed spin labeling (SDSL). Methanethiosulfonate spin label (MTSSL), has become ubiquitous in the SDSL of proteins, however, has limitations owing to its high number of rotamers, and reducibility. In this article we introduce the use of bromoacrylaldehyde spin label (BASL) as a cysteine spin label, demonstrating an advantage over MTSSL due to its increased selectivity for surface cysteines, eliminating the need to ‘knock out’ superfluous cysteine residues. Applied to the multidomain protein, His domain protein tyrosine phosphatase (HD-PTP), we show that BASL can be easily added in excess with selective labeling, whereas MTSSL causes protein precipitation. Furthermore, using DEER, we were able to measure a single cysteine pair distance in a three cysteine domain within HD-PTP. The label has a further advantage of comprising a sulfide in a three-bond tether, making it a candidate for protein binding and in-cell studies.

This study investigated the use of nanozeolites as support for laccases from P. ostreatus (LPO), Aspergillus sp (LAsp) and A. bisporus (LAB) immobilization applied to 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) mediated glycerol oxidation. Selected complexes led to up to 5% glycerol conversion, and interestingly, up to 100% selectivity to glyceraldehyde after 48 h. Free enzymes led to significantly higher yields (up to 82%) but lacked selectivity when tested under the same conditions. These findings suggest that laccases immobilized into nanozeolites are promising catalysts for the selective oxidation of glycerol. With the aim to understand the different behavior of free or immobilized enzymes, electron paramagnetic resonance (EPR) spectroscopy was applied. A significant shift of the T2 parallel copper hyperfine coupling constant was observed. This suggested a perturbation on the catalytic site after immobilization due to pH variation of the enzymatic microenvironments, thus influencing performance of laccase immobilized on nanozeolites.

Diffraction images of cytochrome c peroxidase (CcP, PDB code: 7BIU). They were collected using X-ray free electron laser from SACLA at 15 keV with the serial femtosecond rotation crystallography (SF-ROX) method. The MX300-HS CCD detector was used to record images. CcP crystals belong to P212121 space group with a=50.81, b=75.54, c=106.57 Å. 10303 images were collected from 147 crystals, and 9145 images were merged at 1.06 Å resolution using CrystFEL 0.9.1 in the published result. The experiment was carried out on BL2. Images were converted to HDF5 files with measured photon energies.

Here we provide definitive EPR evidence for the existence of α-triphenylstannylvinyl radicals in the low temperature O-directed free radical hydrostannation of dialkyl propargylic alcohols with Ph3SnH/cat. Et3B and O2 in PhMe. Isotropic hyperfine splitting patterns and spectral simulations confirm the assignments made. In the case of the α-triphenylstannylvinyl radical (Z)-2, an isotopic 119/117Sn hyperfine coupling constant of 9.5 mT (95 G) was measured along with a 1Hβ hyperfine coupling constant of 1.1 mT.

Na2 Ti3 O7 (NTO) is considered a promising anode material for Na-ion batteries due to its layered structure with an open framework and low and safe average operating voltage of 0.3 V vs. Na+ /Na. However, its poor electronic conductivity needs to be addressed to make this material attractive for practical applications among other anode choices. Here, we report a safe, controllable and affordable method using urea that significantly improves the rate performance of NTO by producing surface defects such as oxygen vacancies and hydroxyl groups, and the secondary phase Na2 Ti6 O13 . The enhanced electrochemical performance agrees with the higher Na+ ion diffusion coefficient, higher charge carrier density and reduced bandgap observed in these samples, without the need of nanosizing and/or complex synthetic strategies. A comprehensive study using a combination of diffraction, microscopic, spectroscopic and electrochemical techniques supported by computational studies based on DFT calculations, was carried out to understand the effects of this treatment on the surface, chemistry and electronic and charge storage properties of NTO. This study underscores the benefits of using urea as a strategy for enhancing the charge storage properties of NTO and thus, unfolding the potential of this material in practical energy storage applications.