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X-ray spectroscopy is a valuable technique for the study of many materials systems. Characterizing reactions in situ and operando can reveal complex reaction kinetics, which is crucial to understanding active site composition and reaction mechanisms. In this project, the design, fabrication and testing of an open-source and easy-to-fabricate electrochemical cell for in situ electrochemistry compatible with X-ray absorption spectroscopy in both transmission and fluorescence modes are accomplished via windows with large opening angles on both the upstream and downstream sides of the cell. Using a hobbyist computer numerical control machine and free 3D CAD software, anyone can make a reliable electrochemical cell using this design. Onion-like carbon nanoparticles, with a 1:3 iron-to-cobalt ratio, were drop-coated onto carbon paper for testing in situ X-ray absorption spectroscopy. Cyclic voltammetry of the carbon paper showed the expected behavior, with no increased ohmic drop, even in sandwiched cells. Chronoamperometry was used to apply 0.4 V versus reversible hydrogen electrode, with and without 15 min of oxygen purging to ensure that the electrochemical cell does not provide any artefacts due to gas purging. The XANES and EXAFS spectra showed no differences with and without oxygen, as expected at 0.4 V, without any artefacts due to gas purging. The development of this open-source electrochemical cell design allows for improved collection of in situ X-ray absorption spectroscopy data and enables researchers to perform both transmission and fluorescence simultaneously. It additionally addresses key practical considerations including gas purging, reduced ionic resistance and leak prevention. [ABSTRACT FROM AUTHOR]

Overcoming slow kinetics and high overpotential in electrocatalytic oxygen evolution reaction (OER) requires innovative catalysts and approaches that transcend the scaling relationship between binding energies for intermediates and catalyst surfaces. Inorganic complexes provide unique, customizable geometries, which can help enhance their efficiencies. However, they are unstable and susceptible to chemical reaction under extreme pH conditions. Immobilizing complexes on substrates creates single‐molecule catalysts (SMCs) with functional similarities to single‐atom catalysts (SACs). Here, an efficient SMC, composed of dichloro(1,3‐bis(diphenylphosphino)propane) nickel [NiCl2dppp] anchored to a graphene acid (GA), is presented. This SMC surpasses ruthenium‐based OER benchmarks, exhibiting an ultra‐low onset and overpotential at 10 mAcm−2 when exposed to a static magnetic field. Comprehensive experimental and theoretical analyses imply that an interfacial charge transfer from the Ni center in NiCl2dppp to GA enhances the OER activity. Spectroscopic investigations reveal an in situ geometrical transformation of the complex and the formation of a paramagnetic Ni center, which under a magnetic field, enables spin‐selective electron transfer, resulting in enhanced OER performance. The results highlight the significance of in situ geometric transformations in SMCs and underline the potential of an external magnetic field to enhance OER performance at a single‐molecule level. [ABSTRACT FROM AUTHOR]

This document is a correction to a research article titled "Nickel-Based Single-Molecule Catalysts with Synergistic Geometric Transition and Magnetic Field-Assisted Spin Selection Outperform RuO2 for Oxygen Evolution" published in the journal Advanced Energy Materials. The correction addresses an error in Figure S5d of the supporting information, specifically related to the O1s raw spectrum of NiGA. The corrected data is provided in a revised figure. Additionally, the document includes revised sentences in the "Computation Details" section to provide greater clarity about the methodology used in the research. The authors apologize for the error. [Extracted from the article]

To robustly predict the effects of disturbance and ecosystem changes on species, it is necessary to produce structurally realistic models with high predictive power and flexibility. To ensure that these models reflect the natural conditions necessary for reliable prediction, models must be informed and tested using relevant empirical observations. Pattern‐oriented modelling (POM) offers a systematic framework for employing empirical patterns throughout the modelling process and has been coupled with complex systems modelling, such as in agent‐based models (ABMs). However, while the production of ABMs has been rising rapidly, the explicit use of POM has not increased. Challenges with identifying patterns and an absence of specific guidelines on how to implement empirical observations may limit the accessibility of POM and lead to the production of models which lack a systematic consideration of reality. This review serves to provide guidance on how to identify and apply patterns following a POM approach in ABMs (POM‐ABMs), specifically addressing: where in the ecological hierarchy can we find patterns; what kinds of patterns are useful; how should simulations and observations be compared; and when in the modelling cycle are patterns used? The guidance and examples provided herein are intended to encourage the application of POM and inspire efficient identification and implementation of patterns for both new and experienced modellers alike. Additionally, by generalising patterns found especially useful for POM‐ABM development, these guidelines provide practical help for the identification of data gaps and guide the collection of observations useful for the development and verification of predictive models. Improving the accessibility and explicitness of POM could facilitate the production of robust and structurally realistic models in the ecological community, contributing to the advancement of predictive ecology at large. [ABSTRACT FROM AUTHOR]

In an article published in Advanced Energy Materials, Sreeprasad T. Sreenivasan and his team discuss the use of in-situ geometric changes in single molecule catalysts to enhance electrocatalytic activity under a magnetic field. This innovative approach to spin-polarized oxygen evolution reaction surpasses established benchmarks and opens up new possibilities for magnetically activated single-molecule catalysts. The authors provide a comprehensive analysis of their findings, highlighting the potential applications of this research in the field of energy materials. [Extracted from the article]

Abstract: Proton transfer reactions are of central importance to a wide variety of biochemical processes, though determining proton location and monitoring proton transfers in biological systems is often extremely challenging. Herein, we use two‐color valence‐to‐core X‐ray emission spectroscopy (VtC XES) to identify protonation events across three oxidation states of the O2‐activating, radical‐initiating manganese–iron heterodinuclear cofactor in a class I‐c ribonucleotide reductase. This is the first application of VtC XES to an enzyme intermediate and the first simultaneous measurement of two‐color VtC spectra. In contrast to more conventional methods of assessing protonation state, VtC XES is a more direct probe applicable to a wide range of metalloenzyme systems. These data, coupled to insight provided by DFT calculations, allow the inorganic cores of the MnIVFeIV and MnIVFeIII states of the enzyme to be assigned as MnIV(μ‐O)2FeIV and MnIV(μ‐O)(μ‐OH)FeIII, respectively. [ABSTRACT FROM AUTHOR]

The bioinorganic chemistry community has had a long history of utilizing a diverse range of spectroscopic techniques to obtain detailed geometric and electronic structural insights into metalloprotein active sites. In recent years, the development of beamlines optimized for high-resolution X-ray spectroscopy has provided novel tools for the elucidation of biological active site structures. These methods include both non-resonant and resonant X-ray emission spectroscopy. Herein, we briefly introduce both X-ray absorption and X-ray emission spectroscopy, and the added information that can be obtained through high-resolution measurements. The information content of each spectroscopic approach, as well as the required instrumentation, is discussed. Applications of these methods in bioinorganic chemistry are highlighted. [ABSTRACT FROM AUTHOR]

In this paper, the response to temperature of three physiological processes has been examined in detail in seedlings of sorghum and pearl millet. These have been compared with their field performance under high temperature conditions with the aim of developing laboratory-based screening techniques for seedling thermotolerance. Membrane thermostability, as assessed by electrolyte leakage, seedling re-growth and protein synthetic ability were measured in seedlings exposed to a range of temperatures using a thermal gradient bar, The effect of genotype, seedling age and pre-treatment was examined. Differences between genotypes were only apparent after seedlings had been given a brief high temperature pre-treatment (2 h at 43 °C). Similar results were found with all three methods used and their suitability for use in the screening of large numbers of entries is discussed. Significant correlation was found between the ability of membrane thermostability to acclimate and seedling survival in the field. [ABSTRACT FROM AUTHOR]

Photoassimilate produced by mature leaves is usually loaded into the phloem as sucrose. Transport of sucrose from the mesophyll cells to the phloem might involve an apoplastic step or be entirely symplastic, depending on species. Acid invertase occurs as both soluble and cell-wall-bound forms and has been detected in mature leaves. However, the ability of this enzyme to act as a regulator of carbon export and storage depends on whether it occurs either in the sucrose transport path (which could decrease export), or is located within the mesophyll cells (potentially resulting in intracellular futile cycling between sucrose synthesis in the cytoplasm and hydrolysis in the vacuole). Tissue-level localization of acid invertase was investigated by tissue printing, which establishes protein distribution within a leaf. Antiserum was raised against a synthetic peptide corresponding to a region close to the active site of acid invertase. Tissue prints from Pisum sativum L. and Hordeum vulgare L. showed invertase to be located in the vascular regions, which was not observed in Fuchsia hybrida L. This corresponds to differences in the presence of oligosaccharides in leaf extracts and in the pattern of plasmodesmatal connections between mesophyll cells and the vasculature. We hypothesize that the location of acid invertase activity is implicated in species-specific differences in sucrose and oligosacchande metabolism. [ABSTRACT FROM AUTHOR]

Vegetative plants of Lolium temulentum L, grown at 20°C with an 8 h photoperiod were transferred to either 5 or 2°C (8 h photoperiod) at 4th leaf maturity. Measurement of dry weight gain indicated a marked decline in relative growth rate below 5°C, with growth being reduced as much between 5 and 2°C as between 20 and 5°C. This reduction was not associated with increased mortality and was reversible if plants were returned to 20°C. Tissue explants from cold‐treated plants retained the ability to extend if returned to 20°C Rates of extension in explants were less temperature sensitive than the relative growth rates observed in intact plants. Measurements of photosynthetic capacity, and of the patterns of accumulation of reserve carbohydrate in plants exposed to different temperatures, suggested that the inhibition of growth caused by chilling is not caused by an inability of the plants to fix sufficient carbon. [ABSTRACT FROM AUTHOR]

Leaf sucrose, starch, hexose and maximum extractable soluble acid invertase activity were compared throughout the day in source leaves of 13 plant species chosen for their putative phloem-loading type (apoplastic or symplastic). Four species which represent the different phloem-loading types (tomato, barley, maize and Fuchsia) were studied in detail. Using this information we wished to determine whether a positive correlation between foliar carbohydrates and acid invertase activity exists in leaves from different species and, furthermore, whether this relationship is determined by phloem-loading type. Acid invertase activity was relatively constant throughout the day in all species. The extent of sucrose, hexose and starch accumulation and the sucrose: starch ratio measured at a given time were species-dependent. No correlations were found between foliar soluble acid invertase activity and the hexose, sucrose or starch content of the leaves in any of the species, regardless of phloem-loading type. The species examined could be divided into three distinct groups: (1) high sucrose, low invertase; (2) low sucrose, low invertase; and (3) low sucrose, high invertase. The absence of an inverse relationship between leaf sucrose, hexose or starch contents and endogenous soluble acid invertase suggests that this enzyme is not directly involved in carbon partitioning in leaves but serves an auxiliary function. [ABSTRACT FROM AUTHOR]

A soluble acid invertase was extracted by mechanical disruption of mycelium of the psychrophile Monographella nivalis grown on sucrose in submerged culture. The crude preparation was stable to incubation at pH 6.2 for 1 h at temperatures up to 47 °C and was stable to handling at room temperature. Half of the initial activity was lost after 1 h at 52 °C and all activity was lost after 1 h at 57 °C. A single isoform with activity against sucrose was detected on both native PAGE and IEF activity gels, exhibiting an isoelectric point of pH 3.6. The activity bound tightly to Concanavalin A-sepharose and was not displaced by 500 mM α-methyl mannopyranosidase indicating the enzyme to be a mannose-containing glycoprotein. By gel filtration, the apparent Mr was determined at 195 kDa. The invertase was purified 106-fold by salt precipitation. The partially purified enzyme exhibited maximal activity at pH 4.2 and apparent Michaelis constants for sucrose of 1.2, 2.0 and 2.6 mM at 3, 9 and 15 °C. The activity increased exponentially with temperature in the range 7-55 °C. Q10 fell with increased temperature giving values of 1.96 between 5 and 15 °C and 1.60 between 40 and 50°C. Maximal activity was recorded at 55 °C. Arrhenius analysis of temperature data in the range 7-52 °C produced a continuous linear relationship. The activation energy for sucrose hydrolysis was 38.8 kJ mol-1. The thermal stability and thermal kinetic properties of the invertase were similar to those of invertases from mesophilic organisms. The invertase catalysed fructosyl transfer at 13% of the molar activity against sucrose when assayed under conditions analogous to those in culture. The major fructan products were neokestose, isokestose, kestose and an unidentified tetrasaccharide. Traces of larger fructans were also detected. The transient accumulation of fructan in cultures of M. nivalis can be explained as a side reaction of invertase activity. The enzymological and physiological data do not suggest a cryoprotective function for fructan during the growth of the fungus. [ABSTRACT FROM AUTHOR]

An asporogenous strain of the pink snow mould fungus, Monographella nivalis (Schaffnit) E. Müller, anamorph Gerlachia nivalis Ces. ex Sac.) W. Gams & E. Müller (Syn. Fusarium nivale Ces. ex Sacc.), grew at 5 °C on a defined salts medium plus vitamins and utilized a variety of simple and polymeric carbohydrates as the sole carbon and energy source. Mycelium was grown at temperatures between 3 and 15 °C in aerated submerged fermentation culture in chemically defined mediam plus sucrose. Optimum growth rates of 0.035-0.033 h-1 occurred between 9 and 12 °C. Growth in a simple medium showed that all biochemical and physiological processes necessary for growth were functional at 3 °C. The growth performance of the organism at low temperatures was no better than would be expected from extrapolation of mesophilic growth responses to temperature. The optimum growth temperature of 9-12 °C showed that some biochemical or physiological process was impaired above 12 °C. Uptake and incorporation of 35S-methionine by mycelium at different temperatures showed that general protein synthesis increased up to 25 °C, and hence was not responsible per se for the sensitivity to temperatures above 12 °C. Heat shock proteins were synthesized at the relatively low temperature of 25 °C, consistent with the low temperature optimum for growth. When grown with sucrose as the sole carbon source, the mycelium catalyzed the extracellular hydrolysis of sucrose, releasing glucose and fructose together with a small amount of fructan trisaccharides and a trace of tetra- and penta-saccharides. Fructan accumulation was transient, corresponding with maximal rates of sucrose hydrolysis. Most biomass formation occurred in the absence of fructan in the culture, hence fructan was not necessary for growth at low temperature and did not appear to function as a cryoprotectant. Invertase activity was mostly (60-70%) bound to mycelium; the remainder was free in the culture supernatant. The regulation of invertase expression appeared to be by sucrose-induction, rather than by end-product repression. Rates of sucrose hydrolysis in culture were temperature-sensitive and were markedly depressed above 12c, indicating inhibition of invertase formation. [ABSTRACT FROM AUTHOR]