Investigation Of Structure Research Articles

2D Ruddlesden-Popper Perovskites with Polymer Additive as Stable and Transparent Optoelectronic Materials for Building-Integrated Applications.

We report on the use of 2D Ruddlesden-Popper (RP) perovskites as optoelectronic materials in building-integrated applications, addressing the challenge of balancing transparency, photoluminescence, and stability. With the addition of polyvinylpyrrolidone (PVP), the 2D RP films exhibit superior transparency compared to their 3D counterparts with an average visible transmittance (AVT) greater than 50% and photoluminescence stability under continuous illumination and 85 °C heat for up to 100 h as bare, unencapsulated films. Structural investigations show a stress relaxation in the 3D perovskite films after degradation from thermal aging that is not observed in the 2D RP films, which retain their phase after thermal and light aging. We also demonstrate ultrasmooth, wide-bandgap 2D Dion-Jacobson (DJ) films with PVP incorporation up to 2.95 eV, an AVT above 70%, and roughnesses of ~2 nm. These findings contribute to the development of next-generation solar materials, paving the way for their integration into built structures.

A switch and a failsafe: KatG’s mechanism for preservation of catalase activity using a conformationally dynamic Arg and an active-site Trp

Many novel structural features impart a robust catalase activity to KatG that is absent from all other members of its superfamily. The conformationally dynamic “Arg switch” and oxidizable “proximal Trp” have both figured prominently in investigations of KatG structure and mechanism, but the full scope of their contributions to catalysis remains unclear. The switch (R418) appears to regulate active-site intramolecular electron transfer. The proximal Trp (W321) is a conspicuous site of radical formation, but W321•+ does not appear to participate directly in the KatG catalase cycle. To explore the extent to which these residues may cooperate in KatG’s catalase activity, we generated R418N and W321F/R418N KatG and compared their catalytic and spectroscopic properties to wt KatG. R418N KatG showed pH-independent susceptibility to H2O2-based inactivation, whereas wt KatG only showed this response under conditions where the Arg switch would be oriented away from the active site (i.e., low pH). Peroxidatic electron donors (PxEDs) prevented inactivation of wt and R418N KatG regardless of pH; however, protection of R418N KatG activity by this mechanism produced at least ten-fold greater extents of PxED oxidation. Elimination of the proximal Trp in addition to the Arg switch (i.e., W321F/R418N KatG) resulted in a near complete inability to sustain H2O2 degradation. Remarkably, W321F KatG showed resistance to H2O2-dependent inactivation indistinguishable from wt at pH 7 (i.e., when the Arg switch is oriented toward the active site) but sensitivity to H2O2-dependent inactivation indistinguishable from W321F/R418N KatG at pH 5 (i.e., when the Arg switch is oriented away from the active site). These data suggest loss of the Arg switch (either by mutagenesis or conformationally due to environmental pH) results in a KatG that is substantially compromised in the sustained degradation of H2O2. This can be overcome provided that KatG retains its ability to utilize the proximal Trp as a site of protein-based oxidation and has a PxED available to repair protein oxidation events. However, if both the Arg switch and the proximal Trp are absent, rapid H2O2-dependent inactivation is observed, and PxEDs are unable to effectively intervene to preserve KatG’s catalase activity.

West Barents Sheared Margin Composite Tectono-Sedimentary Element, Norwegian–Greenland Sea and Fram Strait

The West Barents Sheared Margin developed in response to break-up and initial opening of the NE Atlantic and links to the Arctic Eurasia Basin. It consists of three first-order segments: (1) a southern sheared margin segment bounding the deep SW Barents Sea basins; (2) a central rifted margin segment west of Bjørnøya; and (3) a northern initially sheared margin segment that was later exposed to oblique extension west of Svalbard. The geometry of the margin included releasing, as well as restraining, bends that inflicted substantial impact on the deformation along the sheared margin. In light of structural, stratigraphic and sedimentological investigations in recent years, the first-order three-fold subdivision of the Barents shear margin has been strengthened and expanded on. It has become even clearer that this subdivision reflects the margin geometry and the shifting far-field and local stress configurations. Prior to the final stages of rifting and break-up of the NE Atlantic in the Paleogene, the study area was part of a broad and extensive basin province comprising deep sedimentary basins. The line of break-up cut diagonally across the regional basin province so that different parts of it are now located in the mid-Norwegian margin, in the NE Greenland margin and in the SW Barents Sea. These areas share a long and complex history of multiple rift phases throughout Late Paleozoic and Mesozoic times, and information from these areas is integrated into the description of the West Barents Sheared Margin Composite Tectono-Sedimentary Element. The marginal basins in the SW Barents Sea are the least explored area on the Norwegian continental shelf and sporadic exploration activity has had limited success. A petroleum potential still exist that will be elaborated in renewed upcoming activity.

Structural and thermal investigations of the ternary Mg–Zn–Ca system

AbstractMagnesium alloys have become suitable candidates for potential biomedical materials due to their excellent mechanical properties, biocompatibility, and biodegradability. Among different Mg alloys, the Mg–Zn–Ca system is the most popular degradable implant material. The aim of this work is the structure and thermal investigation of the ternary Mg66Zn30Ca4 alloy by a high-energy ball milling process for 5, 8, 13, and 20 h. Morphology changes (SEM) and phase analysis (XRD) of searching materials were investigated. The morphology of the obtained powders and the chemical composition were examined using a scanning electron microscope (SEM) with the energy-dispersive spectrometer (EDS). The distribution of powder size of the samples was determined using the laser particle size analyzer. The thermal characteristics of the powders have been investigated up to 450 °C by differential scanning calorimetry (DSC). Additionally, a microhardness test was carried out. The XRD diffraction patterns of powders show the presence of a solid solution of αMg and the Mg51Zn20 phase. The characteristic Bragg lines of unreacted Zn and Ca can be observed in addition. The DSC analyses showed phase transformations taking place in the alloy. SEM analysis showed a lamellar morphology, which is the result of the deformation process within milling. The results of the microhardness (HV0.05) measuring showed that increasing the milling time improved the microhardness of the Mg66Zn30Ca4 alloy.

Advanced In Situ and Operando Characterization Techniques for Zinc‐Ion Batteries

Aqueous zinc‐ion batteries (AZIB) are increasingly recognized as a promising next‐generation energy storage technology, prized for their affordability and high safety profile. Yet, their widespread adoption is challenged by complex reaction mechanisms and the evolving nature of both the electrode material and interfaces, which remain critical barriers. This review underscores the utility of in situ and operando characterization techniques in AZIB systems, offering invaluable tools for tracking these intricate processes and deepening understanding of energy storage mechanisms. This review presents an extensive overview of cutting‐edge in situ and operando methods, emphasizing their crucial role in structural investigations of materials and interfaces during electrochemical processes. This review particularly focuses on the synergistic application of various in situ techniques, delving into the nuances of experimental setups and data interpretation. Finally, it addresses current challenges in the field and proposes potential strategies, aiming to enhance the impact and broaden the application of these techniques for future advancements and mechanistic insights in AZIB research.

Structure-based investigation of a DNA aptamer targeting PTK7 reveals an intricate 3D fold guiding functional optimization

DNA aptamers have emerged as novel molecular tools in disease theranostics owing to their high binding affinity and specificity for protein targets, which rely on their ability to fold into distinctive three-dimensional (3D) structures. However, delicate atomic interactions that shape the 3D structures are often ignored when designing and modeling aptamers, leading to inefficient functional optimization. Challenges persist in determining high-resolution aptamer-protein complex structures. Moreover, the experimentally determined 3D structures of DNA molecules with exquisite functions remain scarce. These factors impede our comprehension and optimization of some important DNA aptamers. Here, we performed a streamlined solution NMR-based structural investigation on the 41-nt sgc8c, a prominent DNA aptamer used to target membrane protein tyrosine kinase 7, for cancer theranostics. We show that sgc8c prefolds into an intricate three-way junction (3WJ) structure stabilized by long-range tertiary interactions and extensive base-base stackings. Delineated by NMR chemical shift perturbations, site-directed mutagenesis, and 3D structural information, we identified essential nucleotides constituting the key functional elements of sgc8c that are centralized at the core of 3WJ. Leveraging the well-established structure-function relationship, we efficiently engineered two sgc8c variants by modifying the apical loop and introducing L-DNA base pairs to simultaneously enhance thermostability, biostability, and binding affinity for both protein and cell targets, a feat not previously attained despite extensive efforts. This work showcases a simplified NMR-based approach to comprehend and optimize sgc8c without acquiring the complex structure, and offers principles for the sophisticated structure-function organization of DNA molecules.

Investigation of macro and micro sleep structures of first night effect in school-aged children

Investigation of macro and micro sleep structures of first night effect in school-aged children

Superior Electrochemical Performance and Cyclic Stability of WS2@CoMgS//AC Composite on the Nickel-Foam for Asymmetric Supercapacitor Devices

Two-dimensional (2D) sulfide-based transition metal dichalcogenides (TMDs) have shown their crucial importance in energy storage devices. In this study, the tungsten disulfide (WS2) nanosheets were combined with hydrothermally synthesized cobalt magnesium sulfide (CoMgS) nanocomposite for use as efficient electrodes in supercapattery energy storage devices. The characteristics of the WS2@CoMgS nanocomposite were better than those of the WS2 and CoMgS electrodes. XRD, SEM, and BET analyses were performed on the nanocomposite to examine its structure, morphology, and surface area in depth. In three-electrode assemblies, the composite (WS2@CoMgS) electrode showed a high specific capacity of 874.39 C g−1 or 1457.31 F g−1 at 1.5 A g−1. The supercapattery device (WS2@CoMgS//AC) electrode demonstrated a specific capacity of 325 C g−1 with an exceptional rate capability retention of 91% and columbic efficiency of 92% over 7000 cycles, according to electrochemical studies. Additionally, the high energy storage capacity of the WS2@CoMgS composite electrode was proved by structural and morphological investigations.

Structural, optical and magnetic investigations of silver-modified sodium niobate (Na(1-x)AgxNbO3) (x = 0.00, 0.01, 0.05) antiferroelectric ceramics for energy storage applications

Structural, optical and magnetic investigations of silver-modified sodium niobate (Na(1-x)AgxNbO3) (x = 0.00, 0.01, 0.05) antiferroelectric ceramics for energy storage applications

Excited-Ground-State Transition of the RNA Strand Slippage Mechanism Captured by the Base-Specific Force Field.

Excited-ground-state transition and strand slippage of RNA play key roles in transcription and translation of central dogma. Due to limitation of current experimental techniques, the dynamic structure ensembles of RNA remain inadequately understood. Molecular dynamics simulations offer a promising complementary approach, whose accuracy depends on the force field. Here, we develop the new version of RNA base-specific force field (BSFF2) to address underestimation of base pairing stability and artificial backbone conformations. Extensive evaluations on typical RNA systems have comprehensively confirmed the accuracy of BSFF2. Furthermore, BSFF2 demonstrates exceptional efficiency in de novo folding of tetraloops and reproducing base pair reshuffling transition between RNA excited and ground states. Then, we explored the RNA strand slippage mechanism with BSFF2. We conducted a comprehensive three-dimensional structural investigation into the strand slippage of the most complex r(G4C2)9 repeat element and presented the molecular details in the dynamic transition along with the underlying mechanism. Our results of capturing the strand slippage, excited-ground transition, de novo folding, and simulations for various typical RNA motifs indicate that BSFF2 should be one of valuable tools for dynamic conformation research and structure prediction of RNA, and a future contribution to RNA-targeted drug design as well as RNA therapy development.

Preliminary Geological Mapping, Petrographic, and Structural Studies of Precambrian Basement Complex Rocks in Part of Chulwe-Matale, South Kivu, DR Congo

A geological map is a veritable planning tool for the economic development of any nation. This map contains the distribution of various types of bedrock in the area. A geological map of Congo’s geographic landmass has been produced since 1974 with the recently updated map of Kivu (Eastern part of Congo) in February 2018. This map largely omits some local geology of interest, possibly owing to its large area coverage. Thus, local geologic mapping must be encouraged to bridge this lacuna; the focus of this study. Field traversing and rock sample collections were carried out and thin sections of the different rock types were prepared and mounted on glass slides for microscopic observation. Geological mapping revealed that the study area is made of ferruginous, graphitic sandstone schists and quartzite with interbedded metadoleritic sills. The petrographic studies revealed the mineral assemblages of quartz-feldspars-muscovite and olivine-pyroxene and plagioclase feldspars respectively for the first and the second group geological units. The structural investigations come out of two deformation phases: the strike-slip type would be at the origin of the cleavages and folds. It’s related to the D1 of the Kibarian orogeny. The second is an extensive phase responsible for the NW-SE fracturation mapped in the study area. The Matale discordance crosses all these lithologies, a later phase is possible. This discontinuity would have acted in the region studied by switching the lithology units from NE-SW to ENE-WSW orientation. This research recommends that the Chulwe-Matale formations would be typical of the Lower Kibarian (Bugarama group) but the geochronology and geochemical data are lacking to confirm this hypothesis.

Building Functional Liquid‐Based Interfaces: From Mechanism to Application

AbstractFunctional liquid‐based interfaces, with their inhomogeneous regions that emphasize the functionalized liquids, have attracted much interest as a versatile platform for a broad spectrum of applications, from chemical manufacturing to practical uses. These interfaces leverage the physicochemical characteristics of liquids, alongside dynamic behaviors induced by macroscopic wettability and microscopic molecular exchange balance, to allow for tailored properties within their functional structures. In this Minireview, we provide a foundational overview of these functional interfaces, based on the structural investigations and molecular mechanisms of interaction forces that directly modulate functionalities. Then, we discuss design strategies that have been employed in recent applications, and the crucial aspects that require focus. Finally, we highlight the current challenges in functional liquid‐based interfaces and provide a perspective on future research directions.

A Structural Investigation of Quantitative Easing

Abstract Using nonlinear Bayesian methods that fully account for the binding zero lower bound (ZLB), we estimate a large-scale macrofinance DSGE model on U.S. data. Counterfactual analysis suggests that by easing financing conditions, quantitative easing facilitated a net increase in aggregate investment. The resulting expansion of firms’ production capacities lowered their marginal costs. These disinflationary supply side effects dominated over the inflationary effects induced by the stimulus to aggregate demand. At the ZLB, the concomitant rise in real interest rates, in turn, induced a net fall in aggregate consumption.

Experimental investigation of porous gyroid structure: Effect of cell size and porosity on performance

This paper presents an experimental investigation of three triply periodic minimal surface based gyroid sheet samples with varying cell size and porosity. The thermal and hydraulic performances of the samples were analyzed and compared under different design parameters (cell size and porosity). The experimental results revealed that the gyroid structures achieved uniform temperature distribution, allowing for the disruption of the thermal boundary layer and enhancing heat transfer. The gyroid structure characterised by small cell size and low porosity (Gyroid-A: 15 mm/0.75) dissipates more heat from its surface compared to the structure with large cell size and high porosity (Gyroid-C: 32 mm/0.9). Gyroid-A also exhibits higher Nusselt number and convection heat transfer coefficient with 51.5 % increase as compared to Gyroid-C. In addition, Gyroid-A has the lowest thermal resistance (with maximum of 45.4 % reduction) and the highest specific pressure drop as compared to the other gyroid structures. Moreover, Gyroid-A exhibits lower total entropy generation (75.9 % reduction) and higher overall performance evaluation criteria, PEC (more efficient heat transfer in relation to flow resistance) as compared to Gyroid-C. The experimental results of this work is important for the design and optimization of heat transfer applications utilizing gyroid sheet structures for effective heat dissipation.

Investigation of cold tube structure on flow characteristics and energy separation in vortex tube based on numerical and thermodynamic analyses

A combined approach of computational fluid dynamics modelling, experimental validation and thermodynamic analysis is used to investigate the effect of cold end tube geometry (namely, straight tube, divergent tube, convergent tube, and convergent-divergent tube) on flow characteristics and energy separation, which to improve the energy efficiency and sustainability of the vortex tube in industrial applications. The analyses indicate that the highest axial velocity (212 m/s) and swirl velocity (193 m/s) at different axial locations in the cold tube are demonstrated in the divergent and convergent-divergent structures, respectively. The divergent tube shows better energy separation at lower cold mass fraction, while the convergent-divergent tube is dominant at higher cold mass fraction. The highest coefficient of performance is found at μc = 0.6, with maximum cooling and heating energy transfer efficiencies of 0.112 and 0.103, respectively. By innovatively incorporating the work-heat transfer theory into structural investigation of cold tubes, it is found that tangential viscous shear effect is the dominant factor in energy separation process. It is noteworthy that the highest net energy transfer of 973 W is achieved by convergent-divergent tube at a cold mass fraction of 0.7.

Electrical resistivity tomography of a masonry bridge: assessing water infiltration on Prebends Bridge, Durham, UK

ABSTRACT Non-invasive imaging methods are a useful tool in informing conservation actions for historical buildings. Electrical Resistivity Tomography (ERT) is widely used in geophysics to image the subsurface but has been seldom used for non-invasive imaging of small-scale masonry structures. Here, we propose an adaptation of the method allowing non-damaging investigation of larger-scale stone structures. We report results of an ERT survey of Prebends Bridge in Durham, a heritage masonry structure constructed in 1778. Our assessment is based on data acquired on the paved top surface of the bridge, which is subsequently modelled and inverted with the use of open-source software. Final images of the internal structure of the bridge reveal areas of lower electrical resistivity, that we interpret as representing regions of water saturation. Locations of low resistivity areas are in good agreement with the structural defects and patches of seepage observed externally. These results will help inform remediation work, to preserve this historical structure from further water damage. In future studies, time-lapse imaging may help to highlight water pathways unambiguously (through comparison of dry/wet periods), while additional electrode arrays installed on the sides/base of the structure could be used to better constrain 3D internal structure.

Carbamic acid and its dimer: A computational study.

A recent work by Marks et al. on the formation of carbamic acid in NH -CO interstellar ices pointed out its stability in the gas phase and the concomitant production of its dimer. Prompted by these results and the lack of information on these species, we have performed an accurate structural, energetic and spectroscopic investigation of carbamic acid and its dimer. For the former, the structural and spectroscopic characterization employed composite schemes based on coupled cluster (CC) calculations that account for the extrapolation to the complete basis set limit and core correlation effects. A first important outcome is the definitive confirmation of the nonplanarity of carbamic acid, then followed by an accurate estimate of its rotational and vibrational spectroscopy parameters. As far as the carbamic acid dimer is concerned, the investigation started from the identification of its most stable forms. For them, structure and vibrational properties have been evaluated using density functional theory, while a composite scheme rooted in CC theory has been employed for the energetic characterization. Our results allowed us to provide a better interpretation of the feature observed in the recent experiment mentioned above.

Boosting Pt utilization via strategic Co Integration: Structural and mechanistic investigation of High-Performance Pt-Co alloy nanocatalysts for catalytic benzene combustion

Platinum (Pt)-based catalysts exhibit notable efficacy in reducing emissions of hazardous volatile organic compounds (VOCs), such as benzene. Nevertheless, the high cost and limited availability of Pt necessitate exploring reasonable strategies to optimize Pt utilization and enhance catalytic efficiency. Thus, pressing needs emerge to develop efficient Pt-based catalysts. This study investigates the catalytic combustion of benzene utilizing an antimony-doped tin oxide (ATO) supported platinum-cobalt (Pt-Co) alloy catalyst. The incorporation of cobalt into Pt nanoparticles leads to Co atoms occupying bulk sites in the Pt-Co alloy, elevating the surface exposure of Pt atoms and enriching Pt on the surface, thereby providing additional active sites for catalysis. Advanced characterization techniques provide critical insights into the morphology, size distribution, crystallinity and valence states of Pt upon strategic Co alloying. Pt-Co/ATO exhibits exceptional low-temperature activity, achieving 95 % benzene conversion at 170 °C, which is 30 °C lower than the 200 °C required for Pt/ATO. Pressure-dependent kinetic analysis reveals a Langmuir-Hinshelwood mechanism involving the co-adsorption of benzene and oxygen reactants on active Pt-Co alloy sites. This study contributes insights into tuning bimetallic alloy nanostructures to optimize noble metal utilization and catalytic performance for VOC abatement, establishing a foundation for advancing sustainable emissions control technology.

1,2,4-triazine derived binuclear lead(ii) complexes: synthesis, spectroscopic and structural investigations and application in organic light-emitting diodes (OLEDs).

Two novel binuclear complexes of Pb(ii) were synthesized by reacting a 3-(2-pyridyl)-5-(4-methoxyphenyl)-1,2,4-triazine (PMPT) ligand with different anionic co-ligands (1: bromide, 2: acetate and isothiocyanate) in a 1 : 1 molar ratio of PMPT ligands to lead(ii) salts. The complexes, [Pb2(μ-PMPT)2Br4] (1) and [Pb2(μ-PMPT)2((μ-CH3COO)2(NCS)2] (2), were characterized using various physicochemical techniques such as CHN analysis, FT-IR spectroscopy, and 1H NMR spectroscopy. Additionally, their structures were determined using single-crystal X-ray diffraction. Based on the obtained structural parameters, complex 1 exhibited a PbN3Br2 environment, while complex 2 displayed a PbN4O3 environment, with holodirected and hemidirected coordination spheres, respectively. Within the crystal network of the complexes, there were interactions involving C-H⋯X (X: O, S, N) as well as π-π stacking. The Pb(ii) complexes were further investigated for their potential use as the emitting layer in organic light-emitting devices (OLEDs). The current-voltage and luminescence-voltage characteristics, as well as the electroluminescence (EL) properties of the complexes, were studied.

Disposal of spent V2O5-WO3/TiO2 catalysts: A regeneration principle based on structure-activity relationships from carrier transformations

Characterization and evaluation of hazardous spent V2O5-WO3/TiO2 catalysts are critical to determining their treatment or final disposal. This study employs a thermal approach to simulate the preparation of spent catalysts derived from commercial V2O5-WO3/TiO2 catalysts and investigate the structure-activity relationship of the carrier changes during the deactivation process. The results indicate that the catalyst carrier undergoes two processes: an increase in grain size and a transformation in crystal structure. Both structural and catalytic investigations demonstrate that the grain size for catalyst deactivation is 24.62 nm, and the formation of CaWO4 occurs before the crystalline transformation. The specific surface area is susceptible to an increase in grain size. The reactions of selective catalytic reduction involve the participation of both Brønsted acid and Lewis acid sites. The deactivation process of the carrier initially affects Brønsted acid sites, followed by a reduction in Lewis acid sites, resulting in a decline in NH3 adsorption capacity and oxidation. Correlation analysis reveals that changes in the physicochemical properties of the catalyst reduce the NO conversion, with the order being The grain size > Total acid amount > The surface area. It is recommended to recycle the spent catalyst if the carrier grain size is less than 25 nm. The findings of this investigation contribute to expanding the database for evaluating and understanding the physicochemical properties of spent catalysts for disposal.