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Electricity-driven water splitting to produce hydrogen is one of the most efficient ways to alleviate energy crisis and environmental pollution problems, in which the anodic oxygen evolution reaction (OER) is the key half-reaction of performance-limiting in water splitting. Given the complicated reaction process and surface reconstruction of the involved catalysts under actual working conditions, unraveling the real active sites, probing multiple reaction intermediates and clarifying catalytic pathways through in-situ characterization techniques and theoretical calculations are essential. In this review, we summarize the recent advancements in understanding the catalytic process, unlocking the water oxidation active phase and elucidating catalytic mechanism of water oxidation by various in-situ characterization techniques. Firstly, we introduce conventionally proposed traditional catalytic mechanisms and novel evolutionary mechanisms of OER, and highlight the significance of optimal catalytic pathways and intrinsic stability. Next, we provide a comprehensive overview of the fundamental working principles, different detection modes, applicable scenarios, and limitations associated with the in-situ characterization techniques. Further, we exemplified the in-situ studies and discussed phase transition detection, visualization of speciation evolution, electronic structure tracking, observation of reaction active intermediates, and monitoring of catalytic products, as well as establishing catalytic structure–activity relationships and catalytic mechanism. Finally, the key challenges and future perspectives for demystifying the water oxidation process are briefly proposed.

Visible light-active photocatalysts play a crucial role in gas-phase photocatalytic CO 2 reduction, offering significant potential for sustainable energy conversion. Herein, we present the synthesis of spindle-shaped Iron (Fe)-based metal-organic framework (MOF) MIL-88 A, coupled with distinct α-Bi 2 O 3 nanospheres. The α-Bi 2 O 3 /MIL88A heterostructure is formed by interacting opposite surface charges, enhancing visible-light absorption and efficient interfacial charge-carrier separation. Such low-cost photocatalysts have a 1.75 eV band gap and demonstrate enhanced efficacy in converting CO 2 to CO, CH 4 , and H 2 in water without using any sacrificial agents or noble metals compared to pristine MIL88A. In addition, in-situ Electron Spin Resonance (ESR) analyses revealed that these unique catalysts combination promoted enhanced interfacial charge dynamics, creating efficient trapping sites for photogenerated carriers. Further, in-situ Diffuse Reflectance Infrared Fourier Transfer Spectroscopy (DRIFTS) investigation elucidates the plausible reaction mechanism and provides an effective methodology for catalyst screening for CO 2 photoreduction. This study offers an effective approach for synthesizing the earth-abundant heterostructure from metal oxide and low-cost MOFs, enhancing photocatalytic activity for sustainable carbon dioxide conversion into invaluable chemicals., (© 2024 Wiley-VCH GmbH.)

Given the widespread adverse outcomes of stress – exacerbated by the current pandemic – wearable sensing provides unique opportunities for automated stress tracking to inform well-being interventions. However, its success in the wild and at scale depends on the robustness and validity of automated stress inference, which is limited in current systems. In this work, we enumerate the properties of robustness and validity necessary for achieving viable automated stress inference using wearable sensors, and we underscore present challenges to constructing and evaluating these systems. Using these criteria as guiding principles, we present automated stress inference results from a large (N=606) in situ longitudinal wearable and contextual sensing study of information workers. Using a multimodal approach encompassing a wearable sensor, relative location tracking, smartphone usage, and environmental sensing, we trained regression models to predict daily self-reported perceived stress in a participant-independent fashion. Our models significantly outperformed baseline variants with shuffled stress scores and were consistent with small-to-moderate effects. Our findings highlight the performance disparity between robust and valid approaches to automated perceived stress inference and current approaches and suggest that further performance gains might require additional sensing modalities and enhanced contextual awareness than existing approaches. [ABSTRACT FROM AUTHOR]

Additive Manufacturing (AM) is becoming an important technology for manufacturing of metallic materials. Laser-Powder Bed Fusion (L-PBF), Electron beam-Powder Bed Fusion (E-PBF) and Directed Energy Deposition (DED) have attracted significant interest from both the scientific community and the industry since these technologies offer great manufacturing opportunities for niche applications and complex geometries. Understanding the physics behind the complex and dynamic phenomena occurring during these processes is essential for overcoming the barriers that constrain the metal AM development. In-situ synchrotron X-ray characterization is suitable for investigating the microstructure evolution during processing and provides new profound insights. Here, we provide an overview of the research on metal PBF and DED using in-situ synchrotron X-ray imaging, diffraction and small-angle scattering, highlighting the state of the art, the instrumentation, the challenges and the gaps in knowledge that need to be filled. We aim at presenting a scientific roadmap for in-situ synchrotron analysis of metal PBF and DED where future challenges in instrumentation such as the development of experimental stations, sample environments and detectors as well as the need for further application oriented research are included.

The behaviour of traditional roofs affects issues relating to sustainability, zero-carbon targets, and Urban Heat Island (UHI) effect. This paper discusses an innovative approach towards understanding the behaviour of porous, and other types, of roofs in Malta in relation to temperature and moisture characteristics, and to project this behaviour onto a changing climate, predicted to be hotter and drier. The new methodology is being trialled on four roof types, on historic buildings, the innovation being the use of data from co-temporal Earth Observations (EO) and Unmanned Aerial Vehicles (UAVs), in conjunction with in-situ data. This research is helping to develop a new application for Remote Sensing in Cultural Heritage; results should enable recommendations for sustainable use of traditional roof-building techniques. The initial results show that the traditional roof has different (reflective and emissive) properties from the hybrid roof, that are being detected from space, complemented with UAV, hand-held thermal camera and in-situ measurements. These results are preliminary; satellite images for spring/early summer and mid-summer and the corresponding UAV images are expected to provide more conclusive information. These promising results should enable the proof-of-concept to progress onto a larger number and greater variety of roof types, even in other Mediterranean countries. [ABSTRACT FROM AUTHOR]

The high pressure behavior of negative thermal expansion materials continues to be of interest, as their potential use in controlled thermal expansion composites can be affected by irreversible pressure-induced phase transitions. To date, it is not possible to predict the high pressure behavior of these compounds, necessitating measurements on each composition. In this work, high pressure synchrotron powder X-ray diffraction studies of Cr2Mo3O12 and Y2Mo3O12 were conducted in a diamond anvil cell. Chromium molybdate, which adopts the monoclinic P21/a structure under ambient conditions, was found to not undergo any crystalline-crystalline transitions up to 8.9 GPa. The orthorhombic ambient pressure polymorph of yttrium molybdate was found to undergo a phase transition to the monoclinic P21/a scandium tungstate structure below 0.13 GPa. This structure is frequently observed for related materials at low temperatures, but has never been reported for Y2Mo3O12. No additional changes in this material were observed up to 4.9 GPa. The fact that the monoclinic polymorphs of these materials do not undergo phase transitions within the studied pressure range makes them unique among A2M3O12 materials, as most isostructural compositions undergo at least one phase transition to crystalline high pressure phases.

Boron largely increases the ductility of polycrystalline high-temperature Co-Re-Cr alloys. Therefore, the effect of boron addition on the alloy structural characteristics is of large importance for the stability of the alloy at operational temperatures. Along with the Co-solid solution matrix phase transformation from hcp to fcc structure, additional structural effects were observed in situ at very high temperatures (up to 1500 °C) using neutron diffraction (ND) in boron-containing Co-17Re-23Cr alloys. Increasing boron content up to 1000 wt. ppm lowers the temperature at which sublimation of Co and Cr from the matrix occurs. As a result, the composition of the matrix in the surface region is changed leading to the formation of a second and a third matrix hcp phases at high temperatures. The consideration on the lattice parameter dependence on composition was used to identify the new phases appearing at high temperatures. Energy-dispersive spectroscopy and ND results were used to estimate the amount of Co and Cr which sublimated from the surface region of the high-boron sample. In the sense of alloy development, the sublimation of Co and Cr is not critical as the temperature range where it is observed (≥1430 °C) is significantly above the foreseen operation temperature of the alloys (1200 °C). [ABSTRACT FROM AUTHOR]

• In situ observation of solidification and second phase precipitation in S32654. • The σ phase in S32654 is formed by the eutectoid transformation of supersaturated austenite. • The enriched Mo and Cr between dendrites provide compositional conditions for the precipitation of σ phase. By utilizing High-Temperature Confocal Laser Scanning Microscopy (HT-CLSM), the microstructure evolution of S32654 super austenitic stainless steel was observed in situ during both solidification and solid-state phase transition. Moreover, the predominant focus was on investigating the precipitation mechanism of the σ phase. The findings revealed that the initial stages of the solidification process involved the nucleation and growth of austenite, followed by a gradual reduction in the residual liquid phase between dendrites until complete solidification was achieved. Furthermore, as the temperature decreased, the composition of the austenite formed from the residual liquid phase differed from the initially formed austenite, ultimately leading to the formation of granular austenite through extrusion. Below the critical temperature, the excessive amounts of Cr and Mo could not be dissolved in the supersaturated austenite between dendrites, thereby resulting in the instantaneous eutectoid decomposition of austenite, namely γ → γ 2 + σ. [ABSTRACT FROM AUTHOR]

• In-situ heating studies by transmission electron microscopy were performed on uranium-zirconium specimens. • The original lamellar structure transformed during the rapid tests. • Changes started at a high temperature in the zr rich phase. • Formation of globular α-Zr nanograins occurred in the original Zr-rich phase. • The u phase retains the α-phase after cooling. The development of U-Zr metallic nuclear fuel for fast spectrum reactors is impacted by a lack of mechanistic understanding of the fuel behavior evolution under thermal irradiation conditions, despite previous works providing substantial fuel performance data. This work uses in-situ transmission electron microscopy heating experiments to study phase and microstructural evolution in several unirradiated U-10Zr specimens during rapid heating ramps (from room temperature to 1000 °C). The starting α- U + bcc-(Zr, U) eutectic microstructure began to decompose above 600 °C. The decomposition initiated from the bcc (U,Zr) phase. Similar results were observed for all specimens even when fabricated by different routes (e.g., cold rolled or annealed). The impact of observed microstructure and phase evolutions at high temperatures on fuel fabrication and in-pile fuel transient test was also discussed. [ABSTRACT FROM AUTHOR]

Co-Re alloys are being developed to supplement Ni-base superalloys in future gas turbines for ultra-high temperature applications. The finely distributed mono-carbide phase of TaC is an important strengthening phase in this alloy, and interacts with dislocations during high temperature creep deformation. This study aims to determine and to understand the volume fraction and size distribution of TaC precipitates in dependence of C/Ta stoichiometry and heat treatment by means of in-situ small-angle neutron scattering. At measuring temperatures of 1173 K, 1373 K and 1473 K, a stable population of fine TaC <100 nm size is formed during ageing for a wide range of C/Ta stoichiometry but with considerably different volume fraction and coarsening behavior. Important parameters for mechanical properties of the material, such as particle size distribution and inter-particle distance, were determined. It is shown that the phase transformation from γ-matrix (fcc) ↔ ε-matrix (hcp) of the Co-Re matrix has a considerable influence on the TaC precipitate formation. [ABSTRACT FROM AUTHOR]

The aging behavior of commercially produced 18650-type Li-ion cells consisting of a lithium iron phosphate (LFP) based cathode and a graphite anode based on either mesocarbon microbeads (MCMB) or needle coke (NC) is studied by i n situ neutron diffraction and standard electrochemical techniques. While the MCMB cells showed an excellent cycle life with only 8% relative capacity loss (i.e., referenced to the capacity after formation) after 4750 cycles and showed no capacity loss on storage for two years, the needle coke cells suffered a 23% relative capacity loss after cycling and a 11% loss after storage. Based on a combination of neutron diffraction and electrochemical characterization, it is shown that the entire capacity loss for both cell types is dominated by the loss of active lithium; no other aging mechanisms like structural degradation of anode or cathode active materials or deactivation of active material could be found, highlighting the high structural stability of the active material and the excellent quality of the investigated cells. [ABSTRACT FROM AUTHOR]

Boron largely increases the ductility of polycrystalline high-temperature Co–Re–Cr alloys. Therefore, the effect of boron addition on the alloy structural characteristics is of large importance for the stability of the alloy at operational temperatures. Along with the Co-solid solution matrix phase transformation from hcp to fcc structure, additional structural effects were observed in situ at very high temperatures (up to 1500 °C) using neutron diffraction (ND) in boron-containing Co–17Re–23Cr alloys. Increasing boron content up to 1000 wt. ppm lowers the temperature at which sublimation of Co and Cr from the matrix occurs. As a result, the composition of the matrix in the surface region is changed leading to the formation of a second and a third matrix hcp phases at high temperatures. The consideration on the lattice parameter dependence on composition was used to identify the new phases appearing at high temperatures. Energy-dispersive spectroscopy and ND results were used to estimate the amount of Co and Cr which sublimated from the surface region of the high-boron sample. In the sense of alloy development, the sublimation of Co and Cr is not critical as the temperature range where it is observed (≥1430 °C) is significantly above the foreseen operation temperature of the alloys (1200 °C).

High pressure powder X-ray diffraction studies of several A 2 Mo 3 O 12 materials (A 2 =Al 2 , Fe 2 , FeAl, and AlGa) were conducted up to 6–7 GPa. All materials adopted a monoclinic structure under ambient conditions, and displayed similar phase transition behavior upon compression. The initial isotropic compressibility first became anisotropic, followed by a small but distinct drop in cell volume. These patterns could be described by a distorted variant of the ambient pressure polymorph. At higher pressures, a distinct high pressure phase formed. Indexing results confirmed that all materials adopted the same high pressure phase. All changes were reversible on decompression, although some hysteresis was observed. The similarity of the high pressure cells to previously reported Ga 2 Mo 3 O 12 suggested that this material undergoes the same sequence of transitions as all materials investigated in this paper. It was found that the transition pressures for all phase changes increased with decreasing radius of the A-site cations. [ABSTRACT FROM AUTHOR]

In-situ neutron powder diffraction studies of the Half-Heusler phase LiAlSi under high deuterium pressures and first principle calculations of solid solutions of Li x Sr 1− x AlSi and their hydrides Li x Sr 1− x AlSiH were carried out. In contrast to an earlier study, there is no experimental evidence for hydrogen (deuterium) uptake up to gas pressures of 15 MPa and temperatures of 550 °C. Instead a slow decomposition reaction according to LiAlSi+1/2H 2 =LiH+Al+Si was found by in-situ neutron powder diffraction. Theoretical calculations by DFT methods on hypothetical solid solutions of Li x Sr 1− x AlSi show the LiAlSi type to be the energetically most stable structure for 0.7< x and the SrAlSi type structure for lower values of x . Hydrides Li x Sr 1− x AlSiH favor the SrAlSiH type for all values of x instead of the structure proposed earlier with hydrogen occupying tetrahedral voids in a LiAlSi structure. As an alternative for a cubic structure for LiAlSiH, we suggest the existence of LiAlSiH in the trigonal SrAlSiH type structure and it might be a candidate worthwhile to be considered for preparative work. [ABSTRACT FROM AUTHOR]

A new in-situ NMR strategy (termed CLASSIC NMR) for mapping the evolution of crystallization processes is reported, involving simultaneous measurement of both liquid-state and solid-state NMR spectra as a function of time. This combined strategy allows complementary information to be obtained on the evolution of both the solid and liquid phases during the crystallization process. In particular, as crystallization proceeds (monitored by solid-state NMR), the solution state becomes more dilute, leading to changes in solution-state speciation and the modes of molecular aggregation in solution, which are monitored by liquid-state NMR. The CLASSIC NMR experiment is applied here to yield new insights into the crystallization of m-aminobenzoic acid. [ABSTRACT FROM AUTHOR]

Abstract: Neutron diffraction has been used for in-situ studying of the charge–discharge processes in commercial lithium batteries with LiFePO4 (LFP) and graphite electrodes. The diffraction data were obtained with time-of-flight diffractometer in the process of three complete charge–discharge cycles performed at a low rate (0.1 C) at room temperature. The experimental data allowed detailed tracing of the multistage process of Li insertion into graphite followed by the formation of several LiC n phases, as well as the reversible transition of LiFePO4 ↔ FePO4. A comparison of the charge–discharge processes in a battery with a pure LFP cathode and LFP containing ∼1% of vanadium (LFPV) is made. In the second case, an evidently larger part of the anode material passes into the final LiC6 state. Analysis of the diffraction patterns of LFP and LFPV powders revealed a marked shrinkage of crystallite size in the LFPV case, which correlates with better electrochemical properties of LFPV compared to LFP. [Copyright &y& Elsevier]

Abstract: High-Temperature Confocal Laser Scanning Microscopy (HT-CLSM) was used to observe the initiation of incipient melting of primary γ′ in a Ni-base superalloy, and to quantitatively determine the liquation temperature. Specimens were cycled using different heating rates (5 and 50°C/s) to peak temperatures of 1200 and 1300°C to observe the influence of rapid heating on the development in the γ′-morphology. It was found that rapid heating prevented the dissolution of primary γ′, which melts leading to constitutional liquation and the formation of dendritic γ′ at the grain boundaries upon cooling. These observations are discussed in terms of the microstructural development of Nickel-based superalloys during welding, and their potential influence on the properties. [Copyright &y& Elsevier]

Abstract: The electrical, magnetic and structural properties of synthetic chalcopyrite, CuFeS2, have been studied up to 873K using DC resistance measurements performed in-situ during neutron powder diffraction experiments. Under ambient conditions the material adopts the accepted structural model for CuFeS2 in the space group I4̄2d, with the magnetic moment of the Fe3+ cations aligned along [001]. The electrical resistivity is around 0.3Ωcm under ambient conditions, consistent with semiconductor character, and decreases slightly with increase in temperature until a more abrupt fall occurs in the region 750–800K. This abrupt change in resistivity is accompanied by a structural transition to a cubic zinc blende structured phase (space group F4̄3m) in which Cu+ and Fe3+ cations are disordered over the same tetrahedral crystallographic sites and by a simultaneous loss of long-range magnetic order. The implications of these results are discussed in the context of previous studies of the chalcopyrite system. [Copyright &y& Elsevier]

We assess heat and mass transfer limitations in in situ studies of model catalysts with a first-principles based multiscale modeling approach that integrates a detailed description of the surface reaction chemistry and the macro-scale flow structures. Using the CO oxidation at RuO2(110) as a prototypical example we demonstrate that factors like a suppressed heat conduction at the backside of the thin single-crystal, and the build-up of a product boundary layer above the flat-faced surface play a significant role. [ABSTRACT FROM AUTHOR]

In situ characterization and reaction studies of working catalytic systems are an issue of current interest. We present studies on well characterized model systems, i.e., deposited metal nanoparticles, applying a variety of experimental techniques in an attempt to bridge gaps between surface science and catalysis. In particular, we investigate methanol dehydrogenation and ethene hydrogenation under UHV as well as ambient conditions and apply nonlinear optical techniques. We use electron spin resonance to study intermediately formed radicals in Ziegler–Natta polymerization of ethene. It is concluded that there is a chance to transfer results from studies on model systems toward an understanding of catalysis. [Copyright &y& Elsevier]

[Display omitted] • Rosuvastatin calcium used to treat hyperlipidemia. • RC loaded NPs prepared using homogenization method. • Spherical shape of RC in NP by SEM. • RC loaded NP showed enhanced release and permeation than commercial formulations. • Improved oral and reduced lipid levels observed NPs than commercial formulation suspension. The aim of this research was to study the effect of marketed tablet (Crestor®) powder suspension (MTPS) and nanoparticle formulation of rosuvastatin calcium (RC) on the pharmacokinetic (PK) and pharmacodynamic (PD) parameters in hyperlipidemia rats. The hyperlipidemia is induced by intraperitoneal injection of Triton-X-100 in 0.9 %w/v saline solution. The marketed tablet was dispersed into suspension. The RC loaded nanoparticles (RC-NPs) are prepared by homogenization method. The prepared RC-NP formulation was characterized for size, drug excipient compatibility and crystallization by differential scanning calorimeter (DSC), morphology by SEM, stability at room temperature, in-vitro dissolution and in-situ absorption in rats. Further, the pharmacokinetic and pharmacodynamic studies were conducted in hyperlipidemia rats. The size of the RC-NP formulation was found to be 183.4 ± 4.5 nm and to be nearly spherical by SEM. DSC studies revealed that no interaction and RC converted to amorphous form in RC-NP formulation. RC-NP formulation was physically and chemically stable over two months at room temperature. The drug release was found to be 25.8 ± 2.5 and 89.96 ± 2.8 % in five mins, respectively from MTPS and RC-NP formulations. The P eff of MTPS and NP of RC was 1.8 ± 0.2 × 10−5 and 2.7 ± 0.3 × 10-5 cm/s, respectively. From the PK studies, the enhancement in the oral bioavailability was found to be 2.4-folds when compared to MTPS formulation and statistically significant (p < 0.05). PD study of RC-NP formulation in hyperlipidemic rats exhibited decrease in lipid profile for 24 h, while MTPS exhibited a decrease in lipid profile for 12 h. Therefore, the results conclusively demonstrate the nanoparticles of RC showed significant enhancement in the PK and PD parameters. [ABSTRACT FROM AUTHOR]

• Rigid polyurethane foams with different contents of aerogel are prepared. • Cell nucleation is enhanced by the presence of aerogel particles. • Degeneration mechanisms – as observed in-situ – are induced by the presence of particles larger than a few microns. • Low contents of aerogel boost polymerization reaction preventing coalescence and drainage. Water blown rigid polyurethane (RPU) composite foams were produced using different concentrations of nanoporous silica aerogel micrometric powder (0.5, 1 and 3 wt%). The effect of these particles on the foaming kinetics was analysed from a physical and chemical viewpoint. On the physical side, the foaming process was studied by in-situ X-ray radioscopy. The inclusion of aerogel particles in the system delays the foam expansion and enhances the nucleation of cells. However, high amounts of these particles (3 wt%) lead to intense cell coalesce during foam evolution. On the chemical side, the reaction kinetics was investigated by in-situ FTIR spectroscopy and reaction temperature measurements. The addition of low contents of aerogel (below 3 wt%) reduces the conversion of isocyanate while favouring the generation of urethane groups, which explains the higher density of the foams with low aerogel contents. However, the foam with high contents of aerogel (3 wt%) does not change the reaction balance in comparison to the reference. Therefore, this foam presents similar expansion and density to those of the unfilled foam (Reference). Furthermore, higher reaction temperatures were reached by the reference foam during the foaming process, and higher dissipation speeds of these temperatures were detected for the foams containing aerogel with respect to those of the reference foam. [ABSTRACT FROM AUTHOR]