Tryptophan regulates Drosophila zinc stores.

Zinc deficiency is commonly attributed to inadequate absorption of the metal. Instead, we show that body zinc stores in Drosophila melanogaster depend on tryptophan consumption. Hence, a dietary amino acid regulates zinc status of the whole insect­a finding consistent with the widespread requirement of zinc as a protein cofactor. Specifically, the tryptophan metabolite kynurenine is released from insect fat bodies and induces the formation of zinc storage granules in Malpighian tubules, where 3-hydroxykynurenine and xanthurenic acid act as endogenous zinc chelators. Kynurenine functions as a peripheral zinc-regulating hormone and is converted into a 3-hydroxykynurenine­zinc­chloride complex, precipitating within the storage granules. Thus, zinc and the kynurenine pathway­well-known modulators of immunity, blood pressure, aging, and neurodegeneration­are physiologically connected.

X-ray Spectroscopy at the SuperXAS and Debye Beamlines: from in situ to Operando.

Understanding structure-performance relationships are essential for the rational design of new functional materials or in the further optimization of (catalytic) processes. Due to the high penetration depth of the radiation used, synchrotron-based hard X-ray techniques (with energy > 4.5 keV) allow the study of materials under realistic conditions (in situ and operando) and thus play an important role in uncovering structure-performance relationships. X-ray absorption and emission spectroscopies (XAS and XES) give insight into the electronic structure (oxidation state, spin state) and local geometric structure (type and number of nearest neighbor atoms, bond distances, disorder) up to ~5 Å around the element of interest. In this mini review, we will give an overview of the in situ and operando capabilities of the SuperXAS beamline, a facility for hard X-ray spectroscopy, through recent examples from studies of heterogeneous catalysts, electrochemical systems, and photoinduced processes. The possibilities for time-resolved experiments in the time range from ns to seconds and longer are illustrated. The extension of X-ray spectroscopy at the new Debye beamline combined with operando X-ray scattering and diffraction and further developments of time-resolved XES at SuperXAS will open new possibilities after the Swiss Light Source upgrade mid 2025.

Key Recommendations for Antimicrobial Resistance Surveillance: Takeaways From the CAPTURA Project.

Antimicrobial resistance (AMR) is a growing global public health challenge associated with 4.95 million deaths in 2019 and an estimated 10 million deaths per year by 2050 in the absence of coordinated action. A robust AMR surveillance system is therefore required to avert such a scenario. Based on an analysis of country-level AMR data in 8 Capturing Data on Antimicrobial Resistance Patterns and Trends in Use in Regions of Asia (CAPTURA) countries, we present a list of key recommendations to strengthen AMR surveillance. We propose 10 primary considerations under 3 broad categories, including recommendations on (1) laboratory and testing practices, (2) data management and analysis, and (3) data use.

Antimicrobial Resistance Surveillance Methods in Bangladesh: Present and Way Forward.

The Institute of Epidemiology, Disease Control and Research (IEDCR) conducts active, case-based national antimicrobial resistance (AMR) surveillance in Bangladesh. The Capturing Data on Antimicrobial Resistance Patterns and Trends in Use in Regions of Asia (CAPTURA) project accessed aggregated retrospective data from non-IEDCR study sites and 9 IEDCR sites to understand the pattern and extent of AMR and to use analyzed data to guide ongoing and future national AMR surveillance in both public and private laboratories. Record-keeping practices, data completeness, quality control, and antimicrobial susceptibility test practices were investigated in all laboratories participating in case-based IEDCR surveillance and laboratory-based CAPTURA sites. All 9 IEDCR laboratories recorded detailed case-based data (n = 16 816) in electronic format for a priority subset of processed laboratory samples. In contrast, most CAPTURA sites (n = 18/33 [54.5%]) used handwritten registers to store data. The CAPTURA sites were characterized by fewer recorded variables (such as patient demographics, clinical history, and laboratory findings) with 1 020 197 individual data, less integration of patient records with the laboratory information system, and nonuniform practice of data recording; however, data were collected from all available clinical samples. The analyses conducted on AMR data collected by IEDCR and CAPTURA in Bangladesh provide current data collection status and highlight opportunities to improve ongoing data collection to strengthen current AMR surveillance system initiatives. We recommend a tailored approach to conduct AMR surveillance in high-burden, resource-limited settings.

Methodological Approach to Identify and Expand the Volume of Antimicrobial Resistance (AMR) Data in the Human Health Sector in Low- and Middle-Income Countries in Asia: Implications for Local and Regional AMR Surveillance Systems Strengthening.

Antimicrobial resistance (AMR) is a multifaceted global health problem disproportionately affecting low- and middle-income countries (LMICs). The Capturing data on Antimicrobial resistance Patterns and Trends in Use in Regions of Asia (CAPTURA) project was tasked to expand the volume of AMR and antimicrobial use data in Asia. The CAPTURA project used 2 data-collection streams: facility data and project metadata. Project metadata constituted information collected to map out data sources and assess data quality, while facility data referred to the retrospective data collected from healthcare facilities. A down-selection process, labelled "the funnel approach" by the project, was adopted to use the project metadata in prioritizing and selecting laboratories for retrospective AMR data collection. Moreover, the metadata served as a guide for understanding the AMR data once they were collected. The findings from CAPTURA's metadata add to the current discourse on the limitation of AMR data in LMICs. There is generally a low volume of AMR data generated as there is a lack of microbiology laboratories with sufficient antimicrobial susceptibility testing capacity. Many laboratories in Asia are still capturing data on paper, resulting in scattered or unused data not readily accessible or shareable for analyses. There is also a lack of clinical and epidemiological data captured, impeding interpretation and in-depth understanding of the AMR data. CAPTURA's experience in Asia suggests that there is a wide spectrum of capacity and capability of microbiology laboratories within a country and region. As local AMR surveillance is a crucial instrument to inform context-specific measures to combat AMR, it is important to understand and assess current capacity-building needs while implementing activities to enhance surveillance systems.

Deciphering the Mechanism of Crystallization of UiO-66 Metal-Organic Framework.

Zirconium-containing metal-organic framework (MOF) with UiO-66 topology is an extremely versatile material, which finds applications beyond gas separation and catalysis. However, after more than 10 years after the first reports introducing this MOF, understanding of the molecular-level mechanism of its nucleation and growth is still lacking. By means of in situ time-resolved high-resolution mass spectrometry, Zr K-edge X-ray absorption spectroscopy, magic-angle spinning nuclear magnetic resonance spectroscopy, and X-ray diffraction it is showed that the nucleation of UiO-66 occurs via a solution-mediated hydrolysis of zirconium chloroterephthalates, whose formation appears to be autocatalytic. Zirconium-oxo nodes form directly and rapidly during the synthesis, the formation of pre-formed clusters and stable non-stoichiometric intermediates are not observed. The nuclei of UiO-66 possess identical to the crystals local environment, however, they lack long-range order, which is gained during the crystallization. Crystal growth is the rate-determining step, while fast nucleation controls the formation of the small crystals of UiO-66 with a narrow size distribution of about 200 nanometers.

Molecular Dynamics and Structural Studies of Zinc Chloroquine Complexes.

Chloroquine (CQ) is a first-choice drug against malaria and autoimmune diseases. It has been co-administered with zinc against SARS-CoV-2 and soon dismissed because of safety issues. The structural features of Zn-CQ complexes and the effect of CQ on zinc distribution in cells are poorly known. In this study, state-of-the-art computations combined with experiments were leveraged to solve the structural determinants of zinc-CQ interactions in solution and the solid state. NMR, ESI-MS, and X-ray absorption and diffraction methods were combined with ab initio molecular dynamics calculations to address the kinetic lability of this complex. Within the physiological pH range, CQ binds Zn2+ through the quinoline ring nitrogen, forming [Zn(CQH)Clx(H2O)3-x](3+)-x (x = 0, 1, 2, and 3) tetrahedral complexes. The Zn(CQH)Cl3 species is stable at neutral pH and at high chloride concentrations typical of the extracellular medium, but metal coordination is lost at a moderately low pH as in the lysosomal lumen. The pentacoordinate complex [Zn(CQH)(H2O)4]3+ may exist in the absence of chloride. This in vitro/in silico approach can be extended to other metal-targeting drugs and bioinorganic systems.

Origin of the Activity Trend in the Oxidative Dehydrogenation of Ethanol over VOx /CeO2.

Supported vanadia (VOx ) is a versatile catalyst for various redox processes where ceria-supported VOx have shown to be particularly active in the oxidative dehydrogenation (ODH) of alcohols. In this work, we clarify the origin of the volcano-shaped ethanol ODH activity trend for VOx /CeOx catalysts using operando quick V K- and Ce L3 - edge XAS experiments performed under transient conditions. We quantitatively demonstrate that both vanadium and cerium are synergistically involved in alcohol ODH. The concentration of reversible Ce4+ /Ce3+ species was identified as the main descriptor of the alcohol ODH activity. The activity drop in the volcano plot, observed at above ca. 3 V nm-2 surface loading (ca. 30 % of VOx monolayer coverage), is related to the formation of spectator V4+ and Ce3+ species, which were identified here for the first time. These results might prove to be helpful for the rational optimization of VOx /CeO2 catalysts and the refinement of the theoretical models.

Spectroscopy vs. Electrochemistry: Catalyst Layer Thickness Effects on Operando/In Situ Measurements.

In recent years, operando/in situ X-ray absorption spectroscopy (XAS) has become an important tool in the electrocatalysis community. However, the high catalyst loadings often required to acquire XA-spectra with a satisfactory signal-to-noise ratio frequently imply the use of thick catalyst layers (CLs) with large ion- and mass-transport limitations. To shed light on the impact of this variable on the spectro-electrochemical results, in this study we investigate Pd-hydride formation in carbon-supported Pd-nanoparticles (Pd/C) and an unsupported Pd-aerogel with similar Pd surface areas but drastically different morphologies and electrode packing densities. Our in situ XAS and rotating disk electrode (RDE) measurements with different loadings unveil that the CL-thickness largely determines the hydride formation trends inferred from spectro-electrochemical experiments, therewith calling for the minimization of the CL-thickness in such experiments and the use of complementary thin-film control measurements.

Controlling the Strong Metal-Support Interaction Overlayer Structure in Pt/TiO2 Catalysts Prevents Particle Evaporation.

Platinum nanoparticles (NPs) supported by titania exhibit a strong metal-support interaction (SMSI)[1] that can induce overlayer formation and encapsulation of the NP's with a thin layer of support material. This encapsulation modifies the catalyst's properties, such as increasing its chemoselectivity[2] and stabilizing it against sintering.[3] Encapsulation is typically induced during high-temperature reductive activation and can be reversed through oxidative treatments.[1] However, recent findings indicate that the overlayer can be stable in oxygen.[4, 5] Using in situ transmission electron microscopy, we investigated how the overlayer changes with varying conditions. We found that exposure to oxygen below 400 °C caused disorder and removal of the overlayer upon subsequent hydrogen treatment. In contrast, elevating the temperature to 900 °C while maintaining the oxygen atmosphere preserved the overlayer, preventing platinum evaporation when exposed to oxygen. Our findings demonstrate how different treatments can influence the stability of nanoparticles with or without titania overlayers. expanding the concept of SMSI and enabling noble metal catalysts to operate in harsh environments without evaporation associated losses during burn-off cycling.

The Impact of Coronavirus Disease 2019 (COVID-19) on Healthcare-Associated Infections.

BACKGROUND: The profound changes wrought by coronavirus disease 2019 (COVID-19) on routine hospital operations may have influenced performance on hospital measures, including healthcare-associated infections (HAIs). We aimed to evaluate the association between COVID-19 surges and HAI and cluster rates. METHODS: In 148 HCA Healthcare-affiliated hospitals, from 1 March 2020 to 30 September 2020, and a subset of hospitals with microbiology and cluster data through 31 December 2020, we evaluated the association between COVID-19 surges and HAIs, hospital-onset pathogens, and cluster rates using negative binomial mixed models. To account for local variation in COVID-19 pandemic surge timing, we included the number of discharges with a laboratory-confirmed COVID-19 diagnosis per staffed bed per month. RESULTS: Central line-associated blood stream infections (CLABSI), catheter-associated urinary tract infections (CAUTI), and methicillin-resistant Staphylococcus aureus (MRSA) bacteremia increased as COVID-19 burden increased. There were 60% (95% confidence interval [CI]: 23-108%) more CLABSI, 43% (95% CI: 8-90%) more CAUTI, and 44% (95% CI: 10-88%) more cases of MRSA bacteremia than expected over 7 months based on predicted HAIs had there not been COVID-19 cases. Clostridioides difficile infection was not significantly associated with COVID-19 burden. Microbiology data from 81 of the hospitals corroborated the findings. Notably, rates of hospital-onset bloodstream infections and multidrug resistant organisms, including MRSA, vancomycin-resistant enterococcus, and Gram-negative organisms, were each significantly associated with COVID-19 surges. Finally, clusters of hospital-onset pathogens increased as the COVID-19 burden increased. CONCLUSIONS: COVID-19 surges adversely impact HAI rates and clusters of infections within hospitals, emphasizing the need for balancing COVID-related demands with routine hospital infection prevention.

Linking changes in species composition and biomass in a globally distributed grassland experiment.

Global change drivers, such as anthropogenic nutrient inputs, are increasing globally. Nutrient deposition simultaneously alters plant biodiversity, species composition and ecosystem processes like aboveground biomass production. These changes are underpinned by species extinction, colonisation and shifting relative abundance. Here, we use the Price equation to quantify and link the contributions of species that are lost, gained or that persist to change in aboveground biomass in 59 experimental grassland sites. Under ambient (control) conditions, compositional and biomass turnover was high, and losses (i.e. local extinctions) were balanced by gains (i.e. colonisation). Under fertilisation, the decline in species richness resulted from increased species loss and decreases in species gained. Biomass increase under fertilisation resulted mostly from species that persist and to a lesser extent from species gained. Drivers of ecological change can interact relatively independently with diversity, composition and ecosystem processes and functions such as aboveground biomass due to the individual contributions of species lost, gained or persisting.

A Robust and Efficient Propane Dehydrogenation Catalyst from Unexpectedly Segregated Pt2Mn Nanoparticles.

The increasing demand for short chain olefins like propene for plastics production and the availability of shale gas make the development of highly performing propane dehydrogenation (PDH) catalysts, robust toward industrially applied harsh regeneration conditions, a highly important field of research. A combination of surface organometallic chemistry and thermolytic molecular precursor approach was used to prepare a nanometric, bimetallic Pt-Mn material (3 wt % Pt, 1.3 wt % Mn) supported on silica via consecutive grafting of a Mn and Pt precursor on surface OH groups present on the support surface, followed by a treatment under a H2 flow at high temperature. The material exhibits a 70% fraction of the overall Mn as MnII single sites on the support surface; the remaining Mn is incorporated in segregated Pt2Mn nanoparticles. The material shows great performance in PDH reaction with a low deactivation rate. In particular, it shows outstanding robustness during repeated regeneration cycles, with conversion and selectivity stabilizing at ca. 37 and 98%, respectively. Notably, a material with a lower Pt loading of only 0.05 wt % shows an outstanding catalytic performance─initial productivity of 4523 gC3H6/gPt h and an extremely low kd of 0.003 h-1 under a partial pressure of H2, which are among the highest reported productivities. A combined in situ X-ray absorption spectroscopy, scanning transmission electron microscopy, electron paramagnetic resonance, and metadynamics at the density functional theory level study could show that the strong interaction between the MnII-decorated support and the unexpectedly segregated Pt2Mn particles is most likely responsible for the outstanding performance of the investigated materials.

Controlled Formation of Dimers and Spatially Isolated Atoms in Bimetallic Au-Ru Catalysts via Carbon-Host Functionalization.

The introduction of a foreign metal atom in the coordination environment of single-atom catalysts constitutes an exciting frontier of active-site engineering, generating bimetallic low-nuclearity catalysts often exhibiting unique catalytic synergies. To date, the exploration of their full scope is thwarted by (i) the lack of synthetic techniques with control over intermetallic coordination, and (ii) the challenging characterization of these materials. Herein, carbon-host functionalization is presented as a strategy to selectively generate Au-Ru dimers and isolated sites by simple incipient wetness impregnation, as corroborated by careful X-ray absorption spectroscopy analysis. The distinct catalytic fingerprints are unveiled via the hydrogen evolution reaction, employed as a probe for proton adsorption properties. Intriguingly, the virtually inactive Au atoms enhance the reaction kinetics of their Ru counterparts already when spatially isolated, by shifting the proton adsorption free energy closer to neutrality. Remarkably, the effect is magnified by a factor of 2 in dimers. These results exemplify the relevance of controlling intermetallic coordination for the rational design of bimetallic low-nuclearity catalysts.

Beware of beam damage under reaction conditions: X-ray induced photochemical reduction of supported VOx catalysts during in situ XAS experiments.

In situ X-ray absorption spectroscopy (XAS) is a powerful technique for the investigation of heterogeneous catalysts and electrocatalysts. The obtained XAS spectra are usually interpreted from the point of view of the investigated chemical processes, thereby sometimes omitting the fact that intense X-ray irradiation may induce additional transformations in metal speciation and, thus, in the corresponding XAS spectra. In this work, we report on X-ray induced photochemical reduction of vanadium in supported vanadia (VOx) catalysts under reaction conditions, detected at a synchrotron beamline. While this process was not observed in an inert atmosphere and in the presence of water vapor, it occurred at room temperature in the presence of a reducing agent (ethanol or hydrogen) alone or mixed with oxygen. Temperature programmed experiments have shown that X-ray induced reduction of VOx species appeared very clear at 30-100 °C but was not detected at higher temperatures, where the thermocatalytic ethanol oxidative hydrogenation (ODH) takes place. Similar to other studies on X-ray induced effects, we suggest approaches, which can help to mitigate vanadium photoreduction, including defocusing of the X-ray beam and attenuation of the X-ray beam intensity by filters. To recognize beam damage under in situ/operando conditions, we suggest performing X-ray beam switching (on and off) tests at different beam intensities under in situ conditions.

On the effect of metal loading on the reducibility and redox chemistry of ceria supported Pd catalysts.

The effect of Pd loading on the redox characteristics of a ceria support was examined using in situ Pd K-edge XAS, Ce L3-edge XAS and in situ X-ray diffraction techniques. Analysis of the data obtained from these techniques indicates that the onset temperature for the partial reduction of Ce(IV) to Ce(III), by exposure to H2, varies inversely with the loading of Pd. Whilst the onset and completion temperatures of the reduction of Ce(IV) to Ce(III) are different, both samples yield the same maximal fraction of Ce(III) formation independent of Pd loading. Furthermore, the partial reduction of Ce is found to be concurrent with the reduction of PdO and demonstrated that the presence of metallic Pd is necessary for the reduction of the CeO2 support. Upon passivation by room temperature oxidation, a full oxidation of the reduced ceria support was observed. However, only a mild surface oxidation of Pd was identified. The mild passivation of the Pd is found to lead to a highly reactive sample upon a second reduction by H2. The onset of the reduction of Pd and Ce has been demonstrated to be independent of the Pd loading after a mild passivation with both samples exhibiting near room temperature reduction in the presence of H2.

BCC-Cu nanoparticles: from a transient to a stable allotrope by tuning size and reaction conditions.

Metallic copper generally adopts an FCC structure. In this work, we detect highly unusual BCC-structured Cu nanoparticles as a transient intermediate during the H2 reduction of a CuI precursor, [Cu4OtBu4], grafted onto the surface of partially dehydroxylated silica. The Cu BCC structure, assigned by in situ Cu K-edge XANES and EXAFS, as well as in situ synchrotron PXRD, converts upon heating into the most commonly found FCC allotrope. DFT calculations show that the BCC-Cu phase is in fact predicted to be more stable for small particles, and that their stability increases at lower H2 concentrations. Using this knowledge, we show that it is possible to synthesize BCC-structured Cu nanoparticles as a stable allotrope by reduction of the same grafted precursor either in 10% H2 diluted in Ar or 100% H2 at low temperature.

Excitation function of 54Fe(p,α)51Mn from 9.5 MeV to 18 MeV.

Excitation function of the 54Fe(p,α)51Mn reaction was measured from 9.5 to 18 MeV E 0 , p + by activating a foil stack of 54Fe electrodeposited on copper substrates. Residual radionuclides were quantified by HPGe gamma ray spectrometry. Both 51Mn (t 1/2 = 46.2 min, 〈 E ß + 〉 = 963.7 keV , I ß + = 97 % ; E γ = 749.1 keV, I γ = 0.265%) and its radioactive daughter, 51Cr (t 1/2 = 27.704d, E γ = 320.1 keV, I γ = 9.91%), were used to indirectly quantify formation of 51Mn. Results agree within uncertainty to the only other measurement in literature and predictions of default TALYS theoretical code. Final relative uncertainties are within ±12%.

A General Access Route to High-Nuclearity, Metal-Functionalized Molecular Vanadium Oxides.

Molecular metal oxides are key materials in diverse fields like energy storage and conversion, molecular magnetism and as model systems for solid-state metal oxides. To improve their performance and increase the variety of accessible motifs, new synthetic approaches are necessary. Herein, we report a universal, new precursor to access different metal-functionalized polyoxovanadate (POV) clusters. The precursor is synthesized by a novel solid-state thermal treatment procedure. Solution-phase test reactions at room temperature and pressure show that reaction of the precursor with various metal nitrate salts gives access to a range of metal-functionalized POVs. The first nitrate-templated molecular calcium vanadate cluster is reported. We show that this precursor could open new access routes to POV components for molecular magnetism, energy technologies or catalysis.

Beyond nitrogen: phosphorus - estimating the minimum niche dimensionality for resource competition between phytoplankton.

The niche dimensionality required for coexistence is often discussed in terms of the number of limiting resources. N and P limitation are benchmarks for studying phytoplankton interactions. However, it is generally agreed that limitation by small numbers of resources cannot explain the high phytoplankton diversity observed in nature. Here, we parameterised resource competition models using experimental data for six phytoplankton species grown in monoculture with nine potential limiting resources. We tested predicted species biomass from these models against observations in two-species experimental mixtures. Uptake rates were similar across species, following the classic Redfield ratio. Model accuracy levelled out at around three to five resources suggesting the minimum dimensionality of this system. The models included the resources Fe, Mg, Na and S. Models including only N and P always performed poorly. These results suggest that high-dimensional information about resource limitation despite stoichiometric constraints may be needed to accurately predict community assembly.